I have been accused of “cherry-picking” scientific papers for the series on immune activation. This can be a difficult accusation to counter, because it requires an overview of the totality of scientific papers in the field.

“Cherry-picking” is when a non-representative paper is used to make a point that is generally contradicted by most literature in a field. For example, say there are 20 papers on a topic. 19 are generally consistent with one another, and 1 is an outlier with contrary results. Cherry-picking is citing the 1 weird paper and ignoring the other 19.

If I am cherry-picking, it should be easy for critics to find the more numerous papers that contradict the ones I cite (i.e. the 19 papers in the example above). So I ask the critics: “Where are the contrary papers?”

Of course, papers must be sorted and selected to make scientific arguments. There are too many to cite them all. I have selected papers that are most relevant and useful for my arguments. But they are not cherry picked. The papers I use are generally representative of the field of immune activation and brain development. And they are often some of the most highly cited in the field of immune activation.

To prove my non-cherry-picking ways, below is a list of abstracts in the immune activation field that did not make it into the articles. You can see for yourself that they support the thesis here: that immune activation and cytokines-no matter the source-injure the developing brain and cause autism and schizophrenia. Some papers show that postnatal immune activation causes brain injury. Some papers also show that immune activation and cytokines cause epilepsy, which is associated with autism (30% of autistics have epilepsy). Vaccine critics have argued for decades that vaccines cause epilepsy.

This is NOT a “100 studies that prove vaccines cause autism” list. DO NOT construe it as such. Such lists are dumb and unpersuasive. Vaccine activists should stop using this tactic. The “studies list” gambit is like dropping a giant pile of papers on someones desk and saying “here, YOU figure this out, because I don’t know how”.

This list is provided only for the purpose of refuting the “cherry picking” accusation, by showing that the papers cited on VaccinePapers.org are representative.

Have a look. There is lots of interesting stuff here that didn’t make it into the articles.

Relevant text is underlined + bolded.

Maternal Immune Activation Disrupts Dopamine System in the Offspring

Antonio Luchicchi, PhD et al., Department of Biomedical Sciences, University of Cagliari, Monserrato, Italy

International Journal of Neuropsychopharmacology, 2016

Background: In utero exposure to maternal viral infections is associated with a higher incidence of psychiatric disorders with a supposed neurodevelopmental origin, including schizophrenia. Hence, immune response factors exert a negative impact on brain maturation that predisposes the offspring to the emergence of pathological phenotypes later in life. Although ventral tegmental area dopamine neurons and their target regions play essential roles in the pathophysiology of psychoses, it remains to be fully elucidated how dopamine activity and functionality are disrupted in maternal immune activation models of schizophrenia.

Methods: Here, we used an immune-mediated neurodevelopmental disruption model based on prenatal administration of the poly-IC in rats, which mimics a viral infection and recapitulates behavioral abnormalities relevant to psychiatric disorders in the offspring. Extracellular dopamine levels were measured by brain microdialysis in both the nucleus accumbens shell and the medial prefrontal cortex, whereas dopamine neurons in ventral tegmental area were studied by in vivo electrophysiology.

Results: Poly-IC-treated animals, at adulthood, displayed deficits in sensorimotor gating, memory, and social interaction and increased baseline extracellular dopamine levels in the nucleus accumbens, but not in the prefrontal cortex. In poly-IC rats, dopamine neurons showed reduced spontaneously firing rate and population activity.

Conclusions: These results confirm that maternal immune activation severely impairs dopamine system and that the poly-IC model can be considered a proper animal model of a psychiatric condition that fulfills a multidimensional set of validity criteria predictive of human pathology.

Postnatal Systemic Inflammation Exacerbates Impairment of Hippocampal Synaptic Plasticity in an Animal Seizure Model

Yuan-Hao Chen et al. Taipei Medical University Hospital, Taiwan,

Neuroimmunomodulation, 2013

Objective: To investigate the effects of systemic inflammation in the critical postnatal stages on neurophysiological actions of immune processes and neural plasticity in adult rats after kainic acid (KA)-induced seizures. Methods: To determine changes in hippocampal synaptic plasticity after postnatal central nervous system inflammatory responses and seizure attacks, we performed intraperitoneal injections of lipopolysaccharide (LPS) in postnatal Sprague Dawley rats on day 14 (P14) to induce central nervous system inflammation. We then used a KA tail vein injection on P35 to in- duce seizure attacks. We compared the variability in synaptic plasticity in the hippocampal Schaffer collateral-CA1 region of seizure animals with or without LPS-induced inflamma- tion preconditioning. Results: P14 injection of LPS increased susceptibility to seizures, while treatment with KA on P35 induced seizures. Long-term potentiation (LTP) of the Schaffer collateral-CA1 region was impaired in seizure animals, and this effect was more pronounced in the P14 LPS injec tion group. Fluoro-Jade staining revealed an increase in de- generated hippocampal CA1 pyramidal cells in the P14 LPS injection group. Cytokine expression in the hippocampus in the pre-, peri- and postictus periods was greater in P14 LPS rats than in saline-treated rats. Conclusions: Intraperitoneal LPS injection on P14 induces higher cytokine secretion after KA-induced seizures, enhancing neuronal excitability, short- ening seizure onset time and exacerbating neuronal degen- eration and impairment of LTP formation in the hippocam- pal Schaffer collateral-CA1 region. Central nervous system inflammation during critical stages of childhood development could disrupt the balance needed for neurophysiological actions of immune processes, producing direct, pernicious effects on memory, neural plasticity and neurogenesis into adulthood.

NOTE: Study shows that the brain is affected by postnatal immune activation. Postnatal day 14 in rats corresponds to about age 1-2 years in humans, in terms of brain development.



Postnatal Inflammation Increases Seizure Susceptibility in Adult Rats

Michael A. Galic et al.

Epilepsy and Brain Circuits Program, Hotchkiss Brain Institute, Department of Neuroscience, University of Calgary, Canada

Neuroscience 2008 July 2

There are critical postnatal periods during which even subtle interventions can have long-lasting effects on adult physiology. We asked whether an immune challenge during early postnatal development can alter neuronal excitability and seizure susceptibility in adults. Postnatal day 14 (P14) male Sprague Dawley rats were injected with the bacterial endotoxin lipopolysaccharide (LPS), and control animals received sterile saline. Three weeks later, extracellular recordings from hippocampal slices revealed enhanced field EPSP slopes after Schaffer collateral stimulation and increased epileptiform burst-firing activity in CA1 after 4-aminopyridine application. Six to 8 weeks after postnatal LPS injection, seizure susceptibility was assessed in response to lithium– pilocarpine, kainic acid, and pentylenetetrazol. Rats treated with LPS showed significantly greater adult seizure susceptibility to all convulsants, as well as increased cytokine release and enhanced neuronal degeneration within the hippocampus after limbic seizures. These persistent increases in seizure susceptibility occurred only when LPS was given during a critical postnatal period (P7 and P14) and not before (P1) or after (P20). This early effect of LPS on adult seizures was blocked by concurrent intracerebroventricular administration of a tumor necrosis factor α (TNFα) antibody and mimicked by intracerebroventricular injection of rat recombinant TNFα. Postnatal LPS injection did not result in permanent changes in microglial (Iba1) activity or hippocampal cytokine [IL-1β(interleukin-1β) and TNFα] levels, but caused a slight increase in astrocyte (GFAP) numbers. These novel results indicate that a single LPS injection during a critical postnatal period causes a long-lasting increase in seizure susceptibility that is strongly dependent on TNFα.

Intrauterine inflammation, insufficient to induce parturition, still evokes fetal and neonatal brain injury

Michal A. Elovitz, et al. University of Pennsylvania School of Medicine

Int J Dev Neurosci. 2011 October ; 29(6): 663–671

Abnormal development of the fetal brain in utero is now thought to contribute to the etiology of many functional and behavioral disorders that manifest throughout life. While differences in genetic makeup contribute to this, an ‘adverse’ intrauterine environment is a strong modulator of abnormal development. Maternal bacterial and viral infections during pregnancy represent a significant risk factor in several neuropsychiatric disorders with a presumed neurodevelopmental origin, including schizophrenia, autism, and cognitive delay. (Abecasis et al 2002; Brown et al 2004; Brown et al 2009; Ellman et al 2009; Fatemi et al 2002; Rantakallio et al 1997) However, specific infectious agents in this pathogenesis have not been demonstrated. It appears that prenatal inflammation is the greatest determinant of subsequent adverse outcomes for the offspring. While systemic infections during pregnancy are of concern, perhaps of greater concern, is the risk of in utero exposure to localized inflammation. A fetus is exposed to intrauterine inflammation in a woman with preterm labor and/or preterm birth or at any point in gestation when there evidence of chorioamnionitis (infection/inflammation of the fetal membranes). Inflammation is believed to be a leading cause of preterm birth which is defined as delivery at less than 37 weeks of gestation.(Andrews et al 2008; Romero 2007) Intrauterine inflammation, documented by histological examination of the placenta, occurs in approximately 20% of all pregnancies. However, the prevalence of histological chorioamnionitis is dramatically increased in preterm births with approximately 85% of very preterm births demonstrating this finding. (Yoon et al 2000b)

NOTE: This study shows that human infants can suffer brain injury from immune activation.

Transgenerational transmission and modification of pathological traits induced by prenatal immune activation

U Weber-Stadlbauer1,2, J Richetto1, MA Labouesse2, J Bohacek3, IM Mansuy3 and U Meyer1,2

Institute of Pharmacology and Toxicology, University of Zurich-Vetsuisse, Zurich, Switzerland;

Molecular Psychiatry (2016)

Prenatal exposure to infectious or inflammatory insults is increasingly recognized to contribute to the etiology of psychiatric disorders with neurodevelopmental components, including schizophrenia, autism and bipolar disorder. It remains unknown, however, if such immune-mediated brain anomalies can be transmitted to subsequent generations. Using an established mouse model of prenatal immune activation by the viral mimetic poly(I:C), we show that reduced sociability and increased cued fear expression are similarly present in the first- and second-generation offspring of immune-challenged ancestors. We further demonstrate that sensorimotor gating impairments are confined to the direct descendants of infected mothers, whereas increased behavioral despair emerges as a novel phenotype in the second generation. These transgenerational effects are mediated via the paternal lineage and are stable until the third generation, demonstrating transgenerational non-genetic inheritance of pathological traits following in-utero immune activation. Next-generation sequencing further demonstrated unique and overlapping genome- wide transcriptional changes in first- and second-generation offspring of immune-challenged ancestors. These transcriptional effects mirror the transgenerational effects on behavior, showing that prenatal immune activation leads to a transgenerational transmission (presence of similar phenotypes across generations) and modification (presence of distinct phenotypes across generations) of pathological traits. Together, our study demonstrates for, we believe, the first time that prenatal immune activation can negatively affect brain and behavioral functions in multiple generations. These findings thus highlight a novel pathological aspect of this early-life adversity in shaping disease risk across generations.

Inflammation early in life is a vulnerability factor for emotional behavior at adolescence and for lipopolysaccharide-induced spatial memory and neurogenesis alteration at adulthood

Anne-Laure Dinel et al

Journal of Neuroinflammation 2014, 11:155

Background: The postnatal period is a critical time window during which inflammatory events have significant and enduring effects on the brain, and as a consequence, induce alterations of emotional behavior and/or cognition later in life. However, the long-term effect of neonatal inflammation on behavior during adolescence, a sensitive period for the development of neurodevelopmental psychiatric disorders, has been little studied. In this study, we examined whether an early-life inflammatory challenge could alter emotional behaviors and spatial memory at adolescence and adulthood and whether stress axis activity, inflammatory response and neurogenesis were affected.

Methods: Lipopolysaccharide (LPS, 100 μg/kg) was administered to mice on postnatal day (PND) 14 and cytokine expression was measured in the plasma and in brain structures 3 hours later. Anxiety-like and depressive-like behavior (measured in the novelty-suppressed feeding test and the forced swim test, respectively) and spatial memory (Y-maze test) were measured at adolescence (PND30) and adulthood (PND90). Hypothalamic-pituitary-adrenal (HPA) axis activity (plasma corticosterone and glucocorticoid receptors in the hippocampus and prefrontal cortex) was measured at adulthood. In addition, the impact of a novel adult LPS challenge (100 μ/kg) was measured on spatial memory (Y-maze test), neurogenesis (doublecortin-positive cell numbers in the hippocampus) and plasma cytokine expression.

Results: First, we show in PND14 pups that a peripheral administration of LPS induced the expression of pro- and anti-inflammatory cytokines in the plasma and brain structures that were studied 3 hours after administration. Anxiety-like behavior was altered in adolescent, but not in adult, mice, whereas depressive-like behavior was spared at adolescence and increased at adulthood. This was accompanied by a decreased phosphorylation of the glucocorticoid receptor in the prefrontal cortex, with no effect on corticosterone levels. Second, neonatal LPS treatment had no effect on spatial memory in adolescence and adulthood. However, a second challenge of LPS in adulthood impaired spatial memory performance and neurogenesis and increased circulating levels of CCL2.

Conclusions: Our study shows for the first time, in mice, that a peripheral LPS treatment at PND14 differentially alters emotional behaviors, but not spatial memory, at adolescence and adulthood. The behavioral effect of LPS at PND14 could be attributed to HPA axis deregulation and neurogenesis impairment.

NOTE: Study shows that the brain is affected by postnatal immune activation. Postnatal day 14 in mice corresponds to about age 1-2 years in humans, in terms of brain development.

Schizophrenia associated sensory gating deficits develop after adolescent microglia activation

Manuela Eßlinger et al.

Laboratory of Psychoneuroimmunology, Department of Psychiatry, Ruhr University Bochum, Germany

Brain, Behavior, and Immunity (2016)

Maternal infection during pregnancy is a well-established risk factor for schizophrenia in the adult off- spring. Consistently, prenatal Poly(I:C) treatment in mice has been validated to model behavioral and neurodevelopmental abnormalities associated with schizophrenia. By using the Poly(I:C) BALB/c mouse model, we investigated the functional profile of microglia by flow cytometry in relation to progressive behavioral changes from adolescence to adulthood.Prenatal Poly(I:C) treatment induced the expected sensory gating deficits (pre-pulse inhibition (PPI) of the acoustic startle response) in 100 day-old adult offspring, but only in female not in male descendants. No PPI-deficits were present in 30 day-old adolescent mice. Sensory gating deficits in adult females were preceded by a strong M1-type microglia polarization pattern during puberty as determined by flow cyto- metric analysis of multiple pro- and anti-inflammatory surface markers. Microglia activation in females did not persist until adulthood and was absent in behaviorally unaffected male descendants. Further, the specific activation pattern of microglia was not mirrored by a similar activation of peripheral immune cells. We conclude that prenatal Poly(I:C) treatment induces post pubertal deficits in sensory gating which are specifically preceded by a pro-inflammatory activation pattern of microglia during puberty.

Schizophrenia and Autism: Both Shared and Disorder-Specific Pathogenesis Via Perinatal Inflammation?

URS MEYER, JORAM FELDON, AND OLAF DAMMANN

Laboratory of Behavioural Neurobiology [U.M., J.F.], Swiss Federal Institute of Technology (ETH) Zurich,

PEDIATRIC RESEARCH

Prenatal exposure to infection and subsequent inflammatory responses have been implicated in the etiology of schizophrenia and autism. In this review, we summarize current evidence from human and animal studies supporting the hypothesis that the pathogenesis of these two disorders is linked via exposure to inflammation at early stages of development. Moreover, we propose a hypothetical model in which inflammatory mechanisms may account for multiple shared and disorder-specific pathological characteristics of both en- tities. In essence, our model suggests that acute neuroinflammation during early fetal development may be relevant for the induction of psychopathological and neuropathological features shared by schizophrenia and autism, whereas postacute latent and persistent inflammation may contribute to schizophrenia- and autism-specific phenotypes, respectively.

Prenatal immune activation causes hippocampal synaptic deficits in the absence of overt microglia anomalies

Sandra Giovanoli et al.

Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland

Brain, Behavior, and Immunity 55 (2016) 25–38

Prenatal exposure to infectious or inflammatory insults can increase the risk of developing neuropsychiatric disorder in later life, including schizophrenia, bipolar disorder, and autism. These brain disorders are also characterized by pre- and postsynaptic deficits. Using a well-established mouse model of maternal exposure to the viral mimetic polyriboinosinic–polyribocytidilic acid [poly(I:C)], we examined whether prenatal immune activation might cause synaptic deficits in the hippocampal formation of pubescent and adult offspring. Based on the widely appreciated role of microglia in synaptic pruning, we further explored possible associations between synaptic deficits and microglia anomalies in offspring of poly(I: C)-exposed and control mothers. We found that prenatal immune activation induced an adult onset of presynaptic hippocampal deficits (as evaluated by synaptophysin and bassoon density). The early-life insult further caused postsynaptic hippocampal deficits in pubescence (as evaluated by PSD95 and SynGAP density), some of which persisted into adulthood. In contrast, prenatal immune activation did not change microglia (or astrocyte) density, nor did it alter their activation phenotypes. The prenatal manipulation did also not cause signs of persistent systemic inflammation. Despite the absence of overt glial anomalies or systemic inflammation, adult offspring exposed to prenatal immune activation displayed increased hippocampal IL-1b levels. Taken together, our findings demonstrate that age- dependent synaptic deficits and abnormal pro-inflammatory cytokine expression can occur during postnatal brain maturation in the absence of microglial anomalies or systemic inflammation.

Prenatal and Postnatal Animal Models of Immune Activation: Relevance to a Range of Neurodevelopmental Disorders

Louise Harvey, Patricia Boksa

Department of Psychiatry, McGill University, Mental Health University Institute, Quebec, Canada

Journal of Developmental Neurobiology June 2012

Epidemiological evidence has established links between immune activation during the prenatal or early postnatal period and increased risk of developing a range of neurodevelopment disorders in later life. Animal models have been used to great effect to explore the ramifications of immune activation during gestation and neonatal life. A range of behavioral, neurochemical, molecular, and structural outcome measures associated with schizophrenia, autism, cerebral palsy, and epilepsy have been assessed in models of prenatal and postnatal immune activation . However, the epidemiology-driven disease-first approach taken by some studies can be limiting and, despite the wealth of data, there is a lack of consensus in the literature as to the specific dose, timing, and nature of the immunogen that results in replicable and reproducible changes related to a single disease phenotype. In this review, we highlight a number of similarities and differences in models of prenatal and postnatal immune activation currently being used to investigate the origins of schizophrenia, autism, cerebral palsy, epilepsy, and Parkinson’s disease. However, we describe a lack of synthesis not only between but also within disease-specific models. Our inability to compare the equivalency dose of immunogen used is identified as a significant yet easily rem- edied problem. We ask whether early life exposure to infection should be described as a disease-specific or general vulnerability factor for neurodevelopmental dis- orders and discuss the implications that either classifica- tion has on the design, strengths and limitations of future experiments.

Peripheral inflammation increases seizure susceptibility via the induction of neuroinflammation and oxidative stress in the hippocampus

Ying-Hao Ho et al.

Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan

Journal of Biomedical Science (2015) 22:46

Background: Neuroinflammation with activation of microglia and production of proinflammatory cytokines in the brain plays an active role in epileptic disorders. Brain oxidative stress has also been implicated in the pathogenesis of epilepsy. Damage in the hippocampus is associated with temporal lobe epilepsy, a common form of epilepsy in human. Peripheral inflammation may exacerbate neuroinflammation and brain oxidative stress. This study examined the impact of peripheral inflammation on seizure susceptibility and the involvement of neuroinflammation and oxidative stress in the hippocampus.

Results: In male, adult Sprague-Dawley rats, peripheral inflammation was induced by the infusion of Escherichia coli lipopolysaccharide (LPS, 2.5 mg/kg/day) into the peritoneal cavity for 7 days via an osmotic minipump. Pharmacological agents were delivered via intracerebroventricular (i.c.v.) infusion with an osmotic minipump. The level of cytokine in plasma or hippocampus was analyzed by ELISA. Redox-related protein expression in hippocampus was evaluated by Western blot. Seizure susceptibility was tested by intraperitoneal (i.p.) injection of kainic acid (KA, 10 mg/kg).

We found that i.p. infusion of LPS for 7 days induced peripheral inflammation characterized by the increases in plasma levels of interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). This is associated with a significant increase in number of the activated microglia (Iba-1 + cells), enhanced production of proinflammatory cytokines (including IL-1β, IL-6 and TNF-α) , and tissue oxidative stress (upregulations of the NADPH oxidase subunits) in the hippocampus. These cellular and molecular responses to peripheral inflammation were notably blunted by i.c.v. infusion of a cycloxygenase-2 inhibitor, NS398 (5 μg/μl/h). The i.c.v. infusion of tempol (2.5 μg/μl/h), a reactive oxygen species scavenger, protected the hippocampus from oxidative damage with no apparent effect on microglia activation or cytokine production after peripheral inflammation. In the KA-induced seizure model, i.c.v. infusion of both NS398 and tempol ameliorated the increase in seizure susceptibility in animals succumbed to the LPS-induced peripheral inflammation.

Conclusions: Together these results indicated that LPS-induced peripheral inflammation evoked neuroinflammation and the subsequent oxidative stress in the hippocampus, resulting in the increase in KA-induced seizure susceptibility. Moreover, protection from neuroinflammation and oxidative stress in the hippocampus exerted beneficial effect on seizure susceptibility following peripheral inflammation.

NOTE: Shows that “peripheral” inflammation (peripheral = outside the brain) causes microglial activation inside the brain, and cytokine production inside the brain. Also showed that immune activation caused seizure disorder. Vaccines also cause epilepsy, and epilepsy is associated with autism (about 30% of autistics have epilepsy).

Neonatal inflammation produces selective behavioural deficits and alters N-methyl-D-aspartate receptor subunit mRNA in the adult rat brain

E.-M. Harré1,*, M. A. Galic1,*, A. Mouihate, F. Noorbakhsh2, and Q. J. Pittman

1Hotchkiss Brain Institute and Institute of Infection, Immunity and Inflammation, Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary

Eur J Neurosci. 2008 February

Peripheral inflammation causes production of central cytokines that alter transmission at the N- methyl-D-aspartate receptor (NR). During development, NRs are important for synaptic plasticity and network connectivity. We therefore asked if neonatal inflammation would alter expression of NRs in the brain and behavioural performance in adulthood . We gave lipopolysaccharide (LPS) (100 μg/kg, i.p.) or saline to male rats on postnatal day (P)5, P14, P30 or P77 . Subsequently we assessed mRNA levels of the NR1, NR2A, B, C and D subunits in the hippocampus and cortex either acutely (2 h) or in adulthood using real-time reverse transcriptase-polymerase chain reaction. We explored learning and memory behaviours in adult rats using the Morris water maze and contextual fear conditioning paradigms. Hippocampal NR1 mRNA was acutely increased in the P5- and P77-treated rats but was reduced in adults treated with LPS at P5, P30 and P77. P14 LPS-treated rats showed few acute changes but showed pronounced increases in NR2A, B, C and D subunit mRNA later in adulthood. The cortex displayed relatively few acute changes in expression in the neonatal-treated rats; however, it showed robust changes in NR2B, C and D mRNA in all groups given LPS in adulthood. Behavioural deficits were observed specifically in the P5 and P30 LPS-treated groups in the water maze probe trial and fear conditioning tests , consistent with hippocampal NR1 mRNA down-regulation. Thus, a single bout of inflammation during development can programme specific and persistent differences in NR mRNA subunit expression in the hippocampus, which could be associated with behavioural and cognitive deficits in adulthood.

“Central cytokines”= cytokines in the central nervous system

P5, P30 = 5 and 30 days after birth.

Molecular Mechanisms Involved in Injury to the Preterm Brain

Angela M. Kaindl, MD, PhD, Ge ́ raldine Favrais, MD, and Pierre Gressens, MD, PhD

Journal of Child Neurology

Volume 24 Number 9 September

Injury to the premature brain is a major contributor to infant mortality and morbidity, often leading to mental retardation and sensory-motor impairment . The disease process is believed to be caused, sustained, and aggravated by multiple perinatal factors that team up in a multi-hit fashion. Clinical, epidemiological, and experimental studies have revealed that key factors such as inflammation, excitotoxicity, and oxidative stress contribute considerably to white- and gray- matter injury in premature infants, whose brains are particularly susceptible to damage. Depending on the timing, lesions of the immature brain may influence devel- opmental events in their natural sequence and redirect subsequent development. We review current concepts on molecular mechanisms underlying injury to the premature brain.

QUOTE: “The premature brain is believed to be particularly susceptible to multiple perinatal impacts that result in processes such as inflammation , excitotoxicity, and oxidative stress.”

QUOTE: “Microglia are already widely dispersed throughout the immature white matter by 22 weeks of gestation. These cells are fully capable of producing potentially toxic inflammatory mediators, free radicals, and reactive oxygen intermediates.28 The phagocytic activity of microglia and their capacity for oxidative stress- mediated injury are potently enhanced by inflammatory mediators (interferon g, tumor necrosis factor a, interleukin b, and bacterial lipopolysacharide).29 Recent studies of preoligodendrocytes of the same maturational stage as those populated in the immature white matter of the human premature infant show that cells are exquisitely vulnerable to attack by reactive oxygen species (and reactive nitrogen species produced by activated microglia).30 The presence of activated microglia inducing cell death in immature white matter, both in preoligodendrocytes and in astrocytes, has been widely confirmed.31,32

NOTE: Immune activation causes inflammation, excitotoxicity and oxidative stress.

The Time of Prenatal Immune Challenge Determines the Specificity of Inflammation-Mediated Brain and Behavioral Pathology

Urs Meyer et al.

Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology Zurich,

The Journal of Neuroscience, May 3, 2006

Disturbance to early brain development is implicated in several neuropsychiatric disorders including autism, schizophrenia, and mental retardation. Epidemiological studies have indicated that the risk of developing these disorders is enhanced by prenatal maternal infection, presumably as a result of neurodevelopmental defects triggered by cytokine-related inflammatory events. Here, we demonstrate that the effects of maternal immune challenge between middle and late gestation periods in mice are dissociable in terms of fetal brain cytokine responses to maternal inflammation and the pathological consequences in brain and behavior. Specifically, the relative expression of pro- and anti-inflammatory cytokines in the fetal brains in response to maternal immune challenge may be an important determinant among other developmental factors for the precise pathological profile emerging in later life . Thus, the middle and late gestation periods correspond to two windows with differing vulnerability to adult behavioral dysfunction, brain neuropathology in early adolescence, and of the acute cytokine responses in the fetal brain.

MATERNAL INFECTION AND IMMUNE INVOLVEMENT IN AUTISM

Paul H. Patterson

Biology Division, California Institute of Technology Pasadena, CA 91125 USA

Trends Mol Med. 2011 July

Recent studies have highlighted a connection between infection during pregnancy and increased risk for autism in the offspring. Parallel studies of cerebral spinal fluid, blood, and postmortem brains reveal an ongoing, hyper-responsive inflammatory-like state in many young as well as adult autism subjects. There are also indications of gastrointestinal problems in at least a subset of autistic children. Work with animal models of the maternal infection risk factor indicate that aspects of brain and peripheral immune dysregulation can be begin during fetal development and be maintained through adulthood. The offspring of infected, or immune-activated dams also display cardinal behavioral features of autism, as well as neuropathology consistent with that seen in human autism. These rodent models are proving useful for the study of pathogenesis and gene- environment interaction, as well as for the exploration of potential therapeutic strategies.

Maternal immune activation by poly(I:C) induces expression of cytokines IL-1β and IL-13, chemokine MCP-1 and colony stimulating factor VEGF in fetal mouse brain

Géraldine Arrode-Brusés1,4 and Juan L Brusés1,2,3*

Department of Anatomy and Cell Biology, The University of Kansas School of Medicine,

Journal of Neuroinflammation 2012, 9:83

Background: Maternal viral infection during pregnancy is associated with an increase in the incidence of psychiatric disorders with presumed neurodevelopmental origin, including autism spectrum disorders and schizophrenia. The enhanced risk for developing mental illness appears to be caused by deleterious effects of innate immune response-associated factors on the development of the central nervous system , which predispose the offspring to pathological behaviors in adolescence and adulthood. To identify the immune response-associated soluble factors that may affect central nervous system development, we examined the effect of innate immune response activation by polyriboinosinic-polyribocytidylic acid (poly(I:C)), a synthetic analogue of viral double-stranded RNA, on the expression levels of pro- and anti-inflammatory cytokines, chemokines and colony stimulating factors in fetal and postnatal mouse brain 6 h and 24 h after treatment.

Methods: C57BL/6J pregnant mice (gestational day 16) or newborn mice (postnatal day 4) received a single intraperitoneal injection of the synthetic analogue of viral double-stranded RNA poly(I:C) (20 mg/kg). Thirty-two immune response-associated soluble factors, including pro- and anti-inflammatory cytokines, chemokines and colony stimulating factors, were assayed 6 h and 24 h after poly(I:C) injection using multiplexed bead-based immunoassay (Milliplex Map) and processed in a Luminex 100 IS instrument.

Results: Maternal exposure to poly(I:C) at gestational day 16 induced a significant increase in cytokines interleukin (IL)-1β, IL-7 and IL-13; chemokines monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein (MIP)-1α, interferon gamma-induced protein (IP)-10 and monokine induced by IFN-gamma (MIG); and in the colony stimulating factor vascular endothelial growth factor (VEGF) in the fetal brain. IL-1β showed the highest concentration levels in fetal brains and was the only cytokine significantly up-regulated 24 h after maternal poly(I:C) injection, suggesting that IL-1β may have a deleterious impact on central nervous system development. In contrast, poly(I:C) treatment of postnatal day 4 pups induced a pronounced rise in chemokines and colony stimulating factors in their brains instead of the pro- inflammatory cytokine IL-1β.

Conclusions: This study identified a significant increase in the concentration levels of the cytokines IL-1β and IL-13, the chemokine MCP-1 and the colony stimulating factor VEGF in the developing central nervous system during activation of an innate immune response, suggesting that these factors are mediators of the noxious effects of maternal immune activation on central nervous system development, with potential long-lasting effects on animal behavior.

NOTE: This study shows that immune activation in the mother causes immune activation in the fetal brain.

Maternal immune stimulation during pregnancy shapes the immunological phenotype of offspring

Mili Mandal et al.

UMDNJ-Graduate School of Biomedical Sciences, 185 South Orange Avenue, New Jersey

Brain, Behavior, and Immunity 33 (2013) 33–45

Epidemiological studies have associated infection during pregnancy with increased risk of neurodevelopmental disorders in children, which is modeled in rodents by stimulating the immune system of pregnant dams with microorganisms or their mimics, such as poly(I:C) or LPS. In two prenatal mouse models, we show that in utero exposure of the fetus to cytokines/inflammatory mediators elicited by maternal immune stimulation with poly(I:C) yields offspring that exhibit a proinflammatory phenotype due to alterations in developmental programming of their immune system. Changes in the innate and adaptive immune elements of these pro-inflammatory offspring result in more robust responses following expo- sure to immune stimuli than those observed in control offspring from PBS-injected pregnant dams. In the first model, offspring from poly(I:C)-injected immunologically naïve dams showed heightened cellular and cytokine responses 4 h after injection of zymosan, a TLR2 agonist. In the second model, using dams with immunological memory, poly(I:C) injection during pregnancy produced offspring that showed pref- erential differentiation toward Th17 cell development , earlier onset of clinical symptoms of EAE, and more severe neurological deficits following immunization with MOG35-55. Such ‘‘fetal programming’’ in offspring from poly(I:C)-injected dams not only persists into neonatal and adult life, but also can have profound consequences on health and disease.

Maternal immune activation produces neonatal excitability defects in offspring hippocampal neurons from pregnant rats treated

with poly I:C

Eti Patrich1,2,3, Yael Piontkewitz4, Asher Peretz1, Ina Weiner2,3 & Bernard Attali1,3

epartment of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University,

Scientific Reports | January 2016

Maternal immune activation (MIA) resulting from prenatal exposure to infectious pathogens or inflammatory stimuli is increasingly recognized to play an important etiological role in neuropsychiatric disorders with neurodevelopmental features. MIA in pregnant rodents induced by injection of the synthetic double-stranded RNA, Poly I:C, a mimic of viral infection, leads to a wide spectrum of behavioral abnormalities as well as structural and functional defects in the brain. Previous MIA studies using poly I:C prenatal treatment suggested that neurophysiological alterations occur in the hippocampus. However, these investigations used only juvenile or adult animals. We postulated that MIA-induced alterations could occur earlier at neonatal/early postnatal stages. Here we examined the neurophysiological properties of cultured pyramidal-like hippocampal neurons prepared from neonatal (P0-P2) offspring of pregnant rats injected with poly I:C. Offspring neurons from poly I:C-treated mothers exhibited significantly lower intrinsic excitability and stronger spike frequency adaptation, compared to saline. A similar lower intrinsic excitability was observed in CA1 pyramidal neurons from hippocampal slices of two weeks-old poly I:C offspring. Cultured hippocampal neurons also displayed lower frequency of spontaneous firing, higher charge transfer of IPSCs and larger amplitude of miniature IPSCs. Thus, maternal immune activation leads to strikingly early neurophysiological abnormalities in hippocampal neurons.

Maternal immune activation and strain specific interactions in the development of autism-like behaviors in mice

JJ Schwartzer1,2, M Careaga2,3, CE Onore2,3, JA Rushakoff4, RF Berman2,4 and P Ashwood2,3

Department of Psychiatry and Behavioral Sciences, University of California, Davis,

Translational Psychiatry (2013) 3

It is becoming increasingly apparent that the causes of autism spectrum disorders (ASD) are due to both genetic and environmental factors. Animal studies provide important translational models for elucidating specific genetic or environmental factors that contribute to ASD-related behavioral deficits. For example, mouse research has demonstrated a link between maternal immune activation and the expression of ASD-like behaviors. Although these studies have provided insights into the potential causes of ASD, they are limited in their ability to model the important interactions between genetic variability and environmental insults. This is of particular concern given the broad spectrum of severity observed in the human population, suggesting that subpopulations may be more susceptible to the adverse effects of particular environmental insults . It is hypothesized that the severity of effects of maternal immune activation on ASD-like phenotypes is influenced by the genetic background in mice. To test this, pregnant dams of two inbred strains (that is, C57BL/6J and BTBR T þ tf/J) were exposed to the viral mimic polyinosinic-polycytidylic acid (polyI:C), and their offspring were tested for the presence and severity of ASD-like behaviors. To identify differences in immune system regulation, spleens were processed and measured for alterations in induced cytokine responses. Strain-treatment interactions were observed in social approach, ultrasonic vocalization, repetitive grooming and marble burying behaviors. Interestingly, persistent dysregulation of adaptive immune system function was only observed in BTBR mice. Data suggest that behavioral and immunological effects of maternal immune activation are strain- dependent in mice.

Maternal immune activation and abnormal brain development across central nervous system disorders

Irene Knuesel, Laurie Chicha, Markus Britschgi, Scott A. Schobel, Michael Bodmer, Jessica A. Hellings, Stephen Toovey and Eric P. Prinssen

NATURE REVIEWS | NEUROLOGY

VOLUME 10 | NOVEMBER 2014

Abstract | Epidemiological studies have shown a clear association between maternal infection and schizophrenia or autism in the progeny. Animal models have revealed maternal immune activation (mIA) to be a profound risk factor for neurochemical and behavioural abnormalities in the offspring. Microglial priming has been proposed as a major consequence of mIA, and represents a critical link in a causal chain that leads to the wide spectrum of neuronal dysfunctions and behavioural phenotypes observed in the juvenile, adult or aged offspring. Such diversity of phenotypic outcomes in the mIA model are mirrored by recent clinical evidence suggesting that infectious exposure during pregnancy is also associated with epilepsy and, to a lesser extent, cerebral palsy in children. Preclinical research also suggests that mIA might precipitate the development of Alzheimer and Parkinson diseases. Here, we summarize and critically review the emerging evidence that mIA is a shared environmental risk factor across CNS disorders that varies as a function of interactions between genetic and additional environmental factors. We also review ongoing clinical trials targeting immune pathways affected by mIA that may play a part in disease manifestation. In addition, future directions and outstanding questions are discussed, including potential symptomatic, disease-modifying and preventive treatment strategies.

Maternal Immune Activation Alters Nonspatial Information Processing in the Hippocampus of the Adult Offspring

Hiroshi T. Ito1, Stephen E. P. Smith1,2, Elaine Hsiao1, and Paul H. Patterson1,*

1Division of Biology, California Institute of Technology, Pasadena, CA 91125

The observation that maternal infection increases the risk for schizophrenia in the offspring suggests that the maternal immune system plays a key role in the etiology of schizophrenia. In a mouse model, maternal immune activation (MIA) by injection of poly(I:C) yields adult offspring that display abnormalities in a variety of behaviors relevant to schizophrenia. As abnormalities in the hippocampus are a consistent observation in schizophrenia patients, we examined synaptic properties in hippocampal slices prepared from the offspring of poly(I:C)- and saline-treated mothers. Compared to controls, CA1 pyramidal neurons from adult offspring of MIA mothers display reduced frequency and increased amplitude of miniature excitatory postsynaptic currents. In addition, the specific component of the temporoammonic pathway that mediates object-related information displays increased sensitivity to dopamine. To assess hippocampal network function in vivo, we used expression of the immediate early gene, c-Fos, as a surrogate measure of neuronal activity. Compared to controls, the offspring of poly(I:C)-treated mothers display a distinct c-Fos expression pattern in area CA1 following novel object, but not novel location, exposure. Thus, the offspring of MIA mothers may have an abnormality in modality-specific information processing. Indeed, the MIA offspring display enhanced discrimination in a novel object recognition, but not in an object location, task. Thus, analysis of object and spatial information processing at both synaptic and behavioral levels reveals a largely selective abnormality in object information processing in this mouse model. Our results suggest that altered processing of object-related information may be part of the pathogenesis of schizophrenia-like cognitive behaviors.

Maternal Lipopolysaccharide Exposure Promotes Immunological Functional Changes in Adult Offspring CD4+ T Cells

Rong Luan et al.

American Journal of Reproductive Immunology 73 (2015) 522–535

Problem

Maternal immune activation (MIA) is a risk factor for autism and schizophrenia. However, how MIA affects offspring immune function remains unknown.

Method of study

To investigate the effect of MIA on the offspring, pregnant C57BL/6J mice were given an intraperitoneal injection of 50 lg/kg lipopolysaccha- ride (LPS) on gestational day 12.5.

Results

Adult LPS-treated offspring were hyper-reactive to LPS, and enhanced tumor necrosis factor-a production was observed. CD4+ T cells from LPS offspring had an elevated percentage of interferon (IFN)-c+ CD4+ T cells and interleukin (IL)-17A+ CD4+ T cells in the spleen, IL-17A+ CD4+ T cells in the liver, and CD4+ Foxp3+ T cells in the spleen. LPS offspring CD4+ T cells showed increased proliferation and an enhanced survival rate. DNA microarray analysis of resting LPS offspring CD4+ T cells iden- tified eight up-regulated genes, most of which encoded transcription fac- tors. Quantitative liquid chromatography–mass spectrometry identified 18 up-regulated proteins in resting LPS offspring CD4+ T cells and five up-regulated proteins in activated LPS offspring CD4+ T cells, most of which participated in the PANTHER Gene Ontology metabolic process.

Conclusions

Our results showed that MIA up-regulated proteins involved in metabolic process in CD4+ T cells from LPS offspring that might contribute to the hyperactivated immune response of adult LPS offspring.

NOTE: This study showed that immune activation caused life-long inflammation, which is observed in human autism.

LPS Exposure Increases Maternal Corticosterone Levels, Causes Placental Injury and Increases IL-1Β Levels in Adult Rat Offspring: Relevance to Autism

Thiago B. Kirsten et al.

Department of Pathology, School of Veterinary Medicine, University of São Paulo,

PLOS ONE December 2013 | Volume 8 | Issue 12

Maternal immune activation can induce neuropsychiatric disorders, such as autism and schizophrenia. Previous investigations by our group have shown that prenatal treatment of rats on gestation day 9.5 with lipopolysaccharide (LPS; 100 μg/kg, intraperitoneally), which mimics infections by gram-negative bacteria, induced autism-like behavior in male rats, including impaired communication and socialization and induced repetitive/restricted behavior. However, the behavior of female rats was unchanged. Little is known about how LPS-induced changes in the pregnant dam subsequently affect the developing fetus and the fetal immune system. The present study evaluated the hypothalamic-pituitary-adrenal (HPA) axis activity, the placental tissue and the reproductive performance of pregnant Wistar rats exposed to LPS. In the adult offspring, we evaluated the HPA axis and pro-inflammatory cytokine levels with or without a LPS challenge. LPS exposure increased maternal serum corticosterone levels, injured placental tissue and led to higher post-implantation loss, resulting in fewer live fetuses. The HPA axis was not affected in adult offspring. However, prenatal LPS exposure increased IL-1β serum levels, revealing that prenatal LPS exposure modified the immune response to a LPS challenge in adulthood. Increased IL-1β levels have been reported in several autistic patients. Together with our previous studies, our model induced autistic-like behavioral and immune disturbances in childhood and adulthood, indicating that it is a robust rat model of autism.

Long-term pathological consequences of prenatal infection: beyond brain disorders

Marie A. Labouesse et al.

Physiology and Behavior Laboratory, ETH Zurich, Switzerland

Am J Physiol Regul Integr Comp Physiol 309: R1–R12, 2015.

Prenatal immunological adversities such as maternal infection have been widely acknowledged to contribute to an increased risk of neurodevelopmental brain disorders. In recent years, epidemiological and experimental evidence has accumulated to suggest that prenatal exposure to immune challenges can also negatively affect various physiological and metabolic functions beyond those typically associated with primary defects in CNS development. These peripheral changes include excessive accumulation of adipose tissue and increased body weight, impaired glycemic regulation and insulin resistance, altered myeloid lineage development, increased gut permeability, hyperpurinergia, and changes in microbiota composition. Experimental work in animal models further suggests that at least some of these peripheral abnormalities could directly contribute to CNS dysfunctions, so that normalization of peripheral pathologies could lead to an amelioration of behavioral deficits. Hence, seemingly unrelated central and peripheral effects of prenatal infection could represent interrelated pathological entities that emerge in response to a common developmental stressor. Targeting peripheral abnormalities may thus represent a valuable strategy to improve the wide spectrum of behavioral abnormalities that can emerge in subjects with prenatal infection histories.

Long-term effects of maternal immune activation on depression-like behavior in the mouse

D Khan et al.

Transl Psychiatry (2014) 4, e363;

Depression is a debilitating mental disease affecting a large population worldwide, the pathophysiological mechanisms of which remain incompletely understood. Prenatal infection and associated activation of the maternal immune system (MIA) are prominently related to an increased risk for the development of several psychiatric disorders including schizophrenia and autism in the offsprings. However, the role of MIA in the etiology of depression and its neurobiological basis are insufficiently investigated. Here we induced MIA in mice by challenge with polyinosinic:polycytidylic phosphate salt—a synthetic analog of double-stranded RNA, which enhances maternal levels of the cytokine interleukin-6 (IL-6)—and demonstrate a depression-like behavioral phenotype in adult offsprings. Adult offsprings additionally show deficits in cognition and hippocampal long-term potentiation (LTP) accompanied by disturbed proliferation of newborn cells in the dentate gyrus and compromised neuronal maturation and survival. The behavioral, neurogenic and functional deficiencies observed are associated with reduced hippocampal expression of vascular endothelial growth factor (VEGF)A-VEGFR2. IL-6-STAT3-dependent aberrant VEGFA-VEGFR2 signaling is proposed as neurobiological mechanism mediating the effects of MIA on the developing fetal brain and ensuing consequences in adulthood.

NOTE: Interleukin-6 produces effects via a protein called “STAT-3”. This study suggests that immune activation during brain development can cause depression later in life.

Kinetics of asthma- and allergy-associated immune response gene expression in peripheral blood mononuclear cells from vaccinated infants after in vitro re-stimulation with vaccine antigen

Anne I. Lahdenper

Vaccine (2008) 26, 1725—1730

The global expression of immune response genes in infants after vaccination and their role in asthma and allergy is not clearly understood. Pharmacogenomics is ideally suited to study the involved cellular responses, since the expression of thousands of genes can be assessed simultaneously. Here, array technology was used to assess the expression kinetics of immune response genes with association to asthma and allergy in peripheral blood mononuclear cells (PBMC) of five healthy infants after vaccination with Infanrix-Polio + Hib. At 12 h after in vitro re-stimulation of the PBMC with pertussis toxin (PT) antigen, 14 immune response pathways, 33 allergy-related and 66 asthma-related genes were found activated.

NOTE: This study shows that vaccination stimulates gene expression for many different cytokines including IL-6. Vaccination induces a cytokine response, even in healthy subjects not observably harmed by vaccination.

In-vivo rodent models for the experimental investigation of prenatal immune activation effects in neurodevelopmental brain disorders

Urs Meyer et al.

Neuroscience and Biobehavioral Reviews 33 (2009) 1061–1079

Based on the epidemiological association between maternal infection during pregnancy and enhanced risk of neurodevelopmental brain disorders in the offspring, a number of in-vivo models have been established in rats and mice in order to study this link on an experimental basis. These models provide indispensable experimental tools to test the hypothesis of causality in human epidemiological associations , and to explore the critical neuroimmunological and developmental factors involved in shaping the vulnerability to infection-induced neurodevelopmental disturbances in humans. Here, we summarize the findings derived from numerous in-vivo models of prenatal infection and/or immune activation in rats and mice, including models of exposure to influenza virus, bacterial endotoxin, viral- like acute phase responses and specific pro-inflammatory cytokines. Furthermore, we discuss the methodological aspects of these models in relation to their practical implementation and their translatability to the human condition. We highlight that these models can successfully examine the influence of the precise timing of maternal immune activation, the role of pro- and anti-inflammatory cytokines, and the contribution of gene–environment interactions in the association between prenatal immune challenge and postnatal brain dysfunctions. Finally, we discuss that in-vivo models of prenatal immune activation offer a unique opportunity to establish and evaluate early preventive interventions aiming to reduce the risk of long-lasting brain dysfunctions following prenatal exposure to infection.

NOTE: Human studies cannot show causality. Animal experiments are used to show causality.

Immunological stress at the maternal–foetal interface: A link between neurodevelopment and adult psychopathology

Urs Meyer et al.

Brain, Behavior, and Immunity 20 (2006) 378–388

Maternal infection during pregnancy is associated with a higher incidence of mental disorders, including schizophrenia, in the offspring in later life. Our recent attempt to study this link between prenatal immunological challenge and subsequent psychopathology has led to the establishment of a mouse model demonstrating the emergence of multiple psychotic-like phenotypes following immunolog- ical challenge on gestation day (GD) 9. However, little is known about the impact of similar in utero challenge at diVerent times of preg- nancy. Here, we compare the eYcacy of identical maternal immune stimulation induced by the exposure to polyriboinosinic– polyribocytidilic acid (Poly(I:C)) at a dose of 5 mg/kg (i.v.) on distinct days of gestation (GD 6, 9, 13 or 17). The oVspring derived were then compared to those collected from vehicle- and non-treated dams in two paradigms of selective associative learning: latent inhibition (LI) and the US-pre-exposure effect (USPEE). LI deWciency was observed in animals born to dams treated with Poly(I:C) on GD 6, 9 or 13, but not in those on GD17. In contrast, a loss of the USPEE was equivalently seen in all Poly(I:C) treatment groups, regardless of treat- ment times. Evaluation of the acute cytokine response in a separate cohort of pregnant dams receiving Poly(I:C) challenge on either GD9 or GD17 revealed that the ratio of interleukin-10/tumor necrosis factor-? was elevated in the GD17 relative to the GD9 group. The present report thus provides evidence that the acute cytokine reaction as well as the long-term pattern of behavioural sequelae of maternal immune challenge can be affected by its precise timing during pregnancy. The present study provides further support to the use of the prenatal Poly(I:C) model in the elucidation of mechanisms involved in the aetiology and disease process of immuno-precipitated neurodevelopmental mental diseases, including but not limited to, schizophrenia.

NOTE: This study shows that human infants can suffer brain damage from immune activation.

Immune mediators in the brain and peripheral tissues in autism spectrum disorder

Myka L. Estes and A. Kimberley McAllister

NATURE REVIEWS | NEUROSCIENCE

VOLUME 16 | AUGUST 2015

Abstract | Increasing evidence points to a central role for immune dysregulation in autism spectrum disorder (ASD). Several ASD risk genes encode components of the immune system and many maternal immune system-related risk factors — including autoimmunity, infection and fetal reactive antibodies — are associated with ASD. In addition, there is evidence of ongoing immune dysregulation in individuals with ASD and in animal models of this disorder. Recently, several molecular signalling pathways — including pathways downstream of cytokines, the receptor MET, major histocompatibility complex class I molecules, microglia and complement factors — have been identified that link immune activation to ASD phenotypes. Together, these findings indicate that the immune system is a point of convergence for multiple ASD-related genetic and environmental risk factors.

NOTE: This paper argues that all causes of autism do so by causing immune activation.

Analysis of Plasma Multiplex Cytokines for Children With Febrile Seizures and Severe Acute Encephalitis

Journal of Child Neurology 2014, Vol. 29(2) 182-186 a The Author(s) 2013

Mei-Hua Hu, MD1,2,3,

We investigated the plasma cytokine profiles of children with febrile seizures or severe acute encephalitis using multiplex cytometry to evaluate the role of cytokines in these diseases. Interleukin-6, -10, -12p70, -17A, -2, -4, -5, -9, -13, -22, and -1b, interferon-g, and tumor necrosis factor-a were measured in the plasma from children with febrile seizures (n 1⁄4 9) or severe acute encephalitis (n 1⁄4 21). In multivariate analysis, interleukin-6 was significantly increased in the plasma of the febrile seizure patients compared to those with severe acute encephalitis, suggesting that interleukin-6 is activated during the acute stage of a febrile seizure. A lower plasma interleukin-6 concentration was significantly associated with severe acute encephalitis. The cytokine network may be deregulated in severe acute encephalitis via the persistence of an uncontrolled inflammatory state in the brain.

QUOTE: “Of all the studied cytokines, only interleukin-6 was significantly correlated with febrile seizures in multivariate analysis.”

NOTE: This study only looked at blood cytokines, which are not necessarily representative of whats happening in the brain. But it shows that there is a special relationship between febrile seizures and IL-6.

Cytokine and chemokine responses to Japanese encephalitis live attenuated vaccine in a human population

Jiu-Song Zhang

International Journal of Infectious Diseases 16 (2012) e285–e288

Objectives: The SA14-14-2 Japanese encephalitis (JE) live attenuated vaccine is licensed for use only in China, and has provided excellent efficacy in reducing the incidence of JE. The humoral immune response related to the JE vaccination has been well characterized, however cellular immune responses are less well known.

Methods: Thirty-four healthy males who had recently received inoculation with the SA14-14-2 live attenuated vaccine were recruited. Serum samples from these subjects were analyzed for cytokine and chemokine levels using the FlowCytomix method. Results: Eighteen of 34 subjects were positive for JE virus-specific IgG antibodies. Levels of interleukin (IL)-8, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1a, and MIP-1b were significantly higher in the vaccinees than in a control group (p < 0.0001, p < 0.0001, p = 0.021, and p < 0.0001, respectively). IL-6 was detectable in 64.7% of vaccinees, but was not detectable in any of the controls. IL-1b, IL-2, IL-4, IL-5, IL-9, IL-10, IL-12p70, IL-13, IL-17A, IL-22, tumor necrosis factor (TNF)-a, and interferon (IFN)-g were detected in very few subjects or were undetectable in both groups.

Conclusions: IL-6,IL-8,MCP-1,MIP-1a,andMIP-1b may play important roles in the immune response to JE live attenuated vaccine.

NOTE: Even normal and mild vaccine reactions stimulate cytokine responses, but not enough to damage the brain.

Increased levels of HMGB1 and pro-inflammatory cytokines in children with febrile seizures

Jieun Choi1*, Hyun Jin Min2 and Jeon-Soo Shin2,3

Journal of Neuroinflammation 2011, 8:135

Objective: Febrile seizures are the most common form of childhood seizures. Fever is induced by pro- inflammatory cytokines during infection, and pro-inflammatory cytokines may trigger the development of febrile seizures. In order to determine whether active inflammation, including high mobility group box-1 (HMGB1) and pro-inflammatory cytokines, occurs in children with febrile seizures or epilepsy, we analyzed cytokine profiles of patients with febrile seizures or epilepsy.

Methods: Forty-one febrile seizure patients who visited the emergency department of Seoul National University Boramae Hospital from June 2008 to May 2009 were included in this study. Blood was obtained from the febrile seizure child patients within 30 minutes of the time of the seizure; subsequently, serum cytokine assays were performed. Control samples were collected from children with febrile illness without convulsion (N = 41) and similarly analyzed. Serum samples from afebrile status epilepticus attacks in intractable epilepsy children (N = 12), afebrile seizure attacks in generalized epilepsy with febrile seizure plus (GEFSP) children (N = 6), and afebrile non- epileptic controls (N = 7) were also analyzed.

Results: Serum HMGB1 and IL-1b levels were significantly higher in febrile seizure patients than in fever only controls (p < 0.05). Serum IL-6 levels were significantly higher in typical febrile seizures than in fever only controls (p < 0.05). Serum IL-1b levels were significantly higher in status epilepticus attacks in intractable epilepsy patients than in fever only controls (p < 0.05). Serum levels of IL-1b were significantly correlated with levels of HMGB1, IL-6, and TNF-a (p < 0.05).

Conclusions: HMGB1 and pro-inflammatory cytokines were significantly higher in febrile seizure children. Although it is not possible to infer causality from descriptive human studies, our data suggest that HMGB1 and the cytokine network may contribute to the generation of febrile seizures in children. There may be a potential role for anti- inflammatory therapy targeting cytokines and HMGB1 in preventing or limiting febrile seizures or subsequent epileptogenesis in the vulnerable, developing nervous system of children.

NOTE: This study only looked at blood cytokines, which are not necessarily representative of whats happening in the brain.

BRAIN IL-6 AND AUTISM

WEI, a* I. ALBERTS b AND X. LI c a Central Laboratory, Shanxi Provincial People’s Hospital, Affiliate of

Shanxi Medical University, Taiyuan, China

Department of Natural Sciences, LaGuardia CC, CUNY, New York, NY 11101, USA

Department of Neurochemistry, NY State Institute for Basic Research in Developmental Disabilities, New York, NY 10314, USA

Neuroscience 252 (2013) 320–325

Abstract—Autism is a severe neurodevelopmental disor- der characterized by impairments in social interaction, def- icits in verbal and non-verbal communication, and repetitive behavior and restricted interests. Emerging evidence suggests that aberrant neuroimmune responses may contribute to phenotypic deficits and could be appropriate targets for pharmacologic intervention. Interleukin (IL)-6, one of the most important neuroimmune factors, has been shown to be involved in physiological brain development and in several neurological disorders. For instance, findings from postmortem and animal studies suggest that brain IL-6 is an important mediator of autism-like behaviors. In this review, a possible pathological mechanism behind autism is proposed, which suggests that IL-6 elevation in the brain, caused by the activated glia and/or maternal immune activation, could be an important inflammatory cytokine response involved in the mediation of autism-like behaviors through impair- ments of neuroanatomical structures and neuronal plastic- ity. Further studies to investigate whether IL-6 could be used for therapeutic interventions in autism would be of great significance.

NOTE: This review describes the evidence that IL-6 causes autism.

Interleukin-6, a Major Cytokine in the Central Nervous System

Int. J. Biol. Sci. 2012, 8

Interleukin-6 (IL-6) is a cytokine originally identified almost 30 years ago as a B-cell differentiation factor, capable of inducing the maturation of B cells into antibody-producing cells. As with many other cytokines, it was soon realized that IL-6 was not a factor only involved in the immune response, but with many critical roles in major physiological systems including the nervous system. IL-6 is now known to participate in neurogenesis (influencing both neurons and glial cells), and in the response of mature neurons and glial cells in normal conditions and following a wide arrange of injury models. In many respects, IL-6 behaves in a neurotrophin-like fashion, and seemingly makes understandable why the cytokine family that it belongs to is known as neuropoietins. Its expression is affected in several of the main brain diseases, and animal models strongly suggest that IL-6 could have a role in the observed neuropathology and that therefore it is a clear target of strategic therapies.

QUOTE: “ … a single maternal injection of IL-6 during pregnancy causes schizophrenia-like behavioral abnormalities in WT mice but not in IL-6 KO mice [227]. Finally, IL-6 has been found to be increased in the cerebellum of autistic brain [228] and has been suggested to mediate autism-like behaviors [229].”

NOTE: IL-6 KO mice=Mice unable to produce IL-6. If mice cannot produce IL-6, then they do not suffer brain damage indicative of schizophrenia (or autism).

Gender-Dependent Effects of Maternal Immune Activation on the Behavior of Mouse Offspring

Ingrid C. Y. Xuan1, David R. Hampson1,2* 1Department of Pharmaceutical Sciences,

PLOS ONE | www.plosone.org 1 August 2014 | Volume 9 | Issue 8

Autism spectrum disorders are neurodevelopmental disorders characterized by two core symptoms; impaired social interactions and communication, and ritualistic or repetitive behaviors. Both epidemiological and biochemical evidence suggests that a subpopulation of autistics may be linked to immune perturbations that occurred during fetal development. These findings have given rise to an animal model, called the ‘‘maternal immune activation’’ model, whereby the offspring from female rodents who were subjected to an immune stimulus during early or mid-pregnancy are studied. Here, C57BL/6 mouse dams were treated mid-gestation with saline, lipopolysaccharide (LPS) to mimic a bacterial infection, or polyinosinic:polycytidylic acid (Poly IC) to mimic a viral infection. Autism-associated behaviors were examined in the adult offspring of the treated dams. Behavioral tests were conducted to assess motor activity, exploration in a novel environment, sociability, and repetitive behaviors, and data analyses were carried independently on male and female mice. We observed a main treatment effect whereby male offspring from Poly IC-treated dams showed reduced motor activity. In the marble burying test of repetitive behavior, male offspring but not female offspring from both LPS and Poly IC-treated mothers showed increased marble burying. Our findings indicate that offspring from mothers subjected to immune stimulation during gestation show a gender-specific increase in stereotyped repetitive behavior.

NOTE: Human males have a higher rate of autism. There is evidence that this is due to testosterone, since testosterone can amplify immune activation.

From molecules to neural morphology: understanding neuroinflammation in autism spectrum condition

Adam M. H. Young1,2*, Bhismadev Chakrabarti1,3, David Roberts2, Meng-Chuan Lai1,4,5, John Suckling6,7 and Simon Baron-Cohen1,8

Growing evidence points toward a critical role for early (prenatal) atypical neurodevelopmental processes in the aetiology of autism spectrum condition (ASC). One such process that could impact early neural development is inflammation. We review the evidence for atypical expression of molecular markers in the amniotic fluid, serum, cerebrospinal fluid (CSF), and the brain parenchyma that suggest a role for inflammation in the emergence of ASC . This is complemented with a number of neuroimaging and neuropathological studies describing microglial activation. Implications for treatment are discussed.

QUOTE: Aberrant levels of proinflammatory cytokines, interleukin 6 (IL-6), TNF-α and monocyte chemotactic protein-1 (MCP-1), not only in brain specimens and cerebrospinal fluid (CSF; [90, 101]) but also in amniotic fluid [1], index an active inflammatory process both in children and adults with ASC.

Evidence of microglial activation in autism and its possible role in brain underconnectivity

juan i. rodriguez and janet k. kern

Neuron Glia Biology, 2011, 7(2–4), 205–213.

Evidence indicates that children with autism spectrum disorder (ASD) suffer from an ongoing neuroinflammatory process in different regions of the brain involving microglial activation. When microglia remain activated for an extended period, the production of mediators is sustained longer than usual and this increase in mediators contributes to loss of synaptic connections and neuronal cell death. Microglial activation can then result in a loss of connections or underconnectivity. Underconnectivity is reported in many studies in autism. One way to control neuroinflammation is to reduce or inhibit microglial activation. It is plausible that by reducing brain inflammation and microglial activation, the neurodestructive effects of chronic inflammation could be reduced and allow for improved developmental outcomes. Future studies that examine treatments that may reduce microglial activation and neuroinflammation, and ultimately help to mitigate symptoms in ASD, are warranted.

Elucidating the Early Signal Transduction Pathways Leading to Fetal Brain Injury in Preterm Birth

MICHAL A. ELOVITZ, CONJEEVARAM MRINALINI, AND MARY D. SAMMEL

Department of Obstetrics and Gynecology, Department of Biostatistics and Epidemiology

(Pediatr Research 59: 50–55, 2006)

Adverse neurologic outcome, including cerebral palsy, is a significant contributor to long-term morbidity in preterm neonates. However, the mechanisms leading to brain injury in the setting of a preterm birth are poorly understood. In the last decade, there has been a growing body of evidence correlating infection or inflammation with preterm birth. The presence of intrauterine inflammation significantly increases the risk for adverse neurologic outcome in the neonate. These studies were performed to elucidate the early signal transduction pathways activated in the fetal brain that may result in long-term neurologic injury. Using our mouse model of localized intrauterine inflammation, the activation of TH1/TH2 pathways in the placenta, fetus corpus, fetal liver, and fetal brain was investigated. Additional studies determined whether activation of TH1/TH2 pathways could promote cell death and alter glial development. Real-time PCR studies demonstrated that a robust TH1/TH2 response occurs rapidly in the fetal brain after exposure to intrauterine inflammation . The cytokine response in the fetus and placenta was not significantly correlated with the response in the fetal brain. Along with an immune response, cell death pathways were activated early in the fetal brain in response to intrauterine LPS. Implicating TH1/TH2 and cell death pathways in permanent brain injury are our findings of an increase in GFAP mRNA and protein as well as a loss of pro-oligodendrocytes. With increased understanding of the mechanisms by which inflammation promotes brain injury in the preterm neonate , identification of potential targets to limit adverse neonatal outcomes becomes possible.

NOTE: Shows that the developing human brain is damaged by immune activation and cytokines.

Elevated serum levels of macrophage-derived chemokine and thymus and activation-regulated chemokine in autistic children

Laila Yousef AL-Ayadhi1 and Gehan Ahmed Mostafa1,2*

Journal of Neuroinflammation 2013, 10:72

Background: In some autistic children, there is an imbalance of T helper (Th)1/Th2 lymphocytes toward Th2 , which may be responsible for the induction of the production of autoantibodies in these children. Th2 lymphocytes express CCR4 receptors. CCR4 ligands include macrophage-derived chemokine (MDC) and thymus and activation-regulated chemokine (TARC). They direct trafficking and recruitment of Th2 cells. We are the first to measure serum levels of CCR4 ligands in relation to the degree of the severity of autism.

Methods: Serum concentrations of MDC and TARC were measured, by quantitative sandwich enzyme immunoassay technique, in 56 autistic children and 32 healthy matched children.

Results: Autistic children had significantly higher serum levels of MDC and TARC than healthy controls (P <0.001 and P <0.001, respectively). Children with severe autism had significantly higher serum levels of MDC and TARC than patients with mild to moderate autism (P <0.001 and P = 0.01, respectively). In addition, there were significant positive correlations between CARS and serum levels of both MDC (P <0.001) and TARC (P <0.001) in children with autism. There were significant positive correlations between serum levels of MDC and TARC in autistic children (P <0.001).

Conclusions: Serum levels of CCR4 ligands were elevated in autistic children and they were significantly correlated to the degree of the severity of autism. However, further research is warranted to determine the pathogenic role of CCR4 ligands in autism and to shed light on the therapeutic role of CCR4-ligand antagonism in autistic children.

NOTE: Aluminum adjuvant causes a shift in immune function towards Th2.

Elevated cytokine levels in children with autism spectrum disorder

Cynthia A. Molloy et al.

Journal of Neuroimmunology 172 (2006)

This study compared production of IL-2, IFN-g, IL-4, IL-13, IL-5 and IL-10 in peripheral blood mononuclear cells from 20 children with autism spectrum disorder to those from matched controls. Levels of all Th2 cytokines were significantly higher in cases after incubation in media alone, but the IFN-g/IL-13 ratio was not significantly different between cases and controls. Cases had significantly higher IL-13/IL-10 and IFN-g/IL-10 than controls. Conclusion: Children with ASD had increased activation of both Th2 and Th1 arms of the adaptive immune response, with a Th2 predominance, and without the compensatory increase in the regulatory cytokine IL-10.

Of Mice and Not Men: Differences between Mouse and Human Immunology

Javier Mestas and Christopher C. W. Hughes1

The Journal of Immunology, 2004, 172: 2731–2738.

Mice are the experimental tool of choice for the majority of immunologists and the study of their immune responses has yielded tremendous insight into the workings of the human immune system. However, as 65 million years of evolution might suggest, there are significant differences. Here we outline known discrepancies in both innate and adaptive immunity, including: balance of leukocyte sub- sets, defensins, Toll receptors, inducible NO synthase, the NK inhibitory receptor families Ly49 and KIR, FcR, Ig subsets, the B cell (BLNK, Btk, and ?5) and T cell (ZAP70 and common ?-chain) signaling pathway com- ponents, Thy-1, ?? T cells, cytokines and cytokine recep- tors, Th1/Th2 differentiation, costimulatory molecule expression and function, Ag-presenting function of endo- thelial cells, and chemokine and chemokine receptor ex- pression. We also provide examples, such as multiple scle- rosis and delayed-type hypersensitivity, where complex multicomponent processes differ. Such differences should be taken into account when using mice as preclinical models of human disease.

VP NOTE: This paper is important for what it does NOT report. It does NOT report any differences in IL-6 function in humans and mice.

Dietary supplementation with omega-3 fatty acids from weaning limits brain biochemistry and behavioural changes elicited by prenatal exposure to maternal inflammation in the mouse model

Q Li et al.

Transl Psychiatry (2015) 5

Prenatal exposure to maternal immune activation (MIA) increases the risk of schizophrenia and autism in the offspring. The MIA rodent model provides a valuable tool to directly test the postnatal consequences of exposure to an early inflammatory insult; and examine novel preventative strategies. Here we tested the hypotheses that behavioural differences in the MIA mouse model are accompanied by in vivo and ex vivo alterations in brain biochemistry; and that these can be prevented by a post-weaning diet enriched with omega-3 polyunsaturated fatty acid (PUFA). The viral analogue PolyI:C (POL) or saline (SAL) was administered to pregnant mice on gestation day 9. Half the resulting male offspring (POL = 21; SAL = 17) were weaned onto a conventional lab diet (n-6 PUFA); half were weaned onto omega-3 PUFA-enriched diet. In vivo magnetic resonance spectroscopy measures were acquired prior to behavioural tests; glutamic acid decarboxylase 67 (GAD67) and tyrosine hydroxylase protein levels were measured ex vivo. The main findings were: (i) Adult MIA-exposed mice fed a standard diet had greater N-acetylaspartate/creatine (Cr) and lower myo-inositol/Cr levels in the cingulate cortex in vivo. (ii) The extent of these metabolite differences was correlated with impairment in prepulse inhibition. (iii) MIA-exposed mice on the control diet also had higher levels of anxiety and altered levels of GAD67 ex vivo. (iv) An n-3 PUFA diet prevented all the in vivo and ex vivo effects of MIA observed. Thus, omega-3 PUFA dietary enrichment from early life may offer a relatively safe and non-toxic approach to limit the otherwise persistent behavioural and biochemical consequences of prenatal exposure to inflammation. This result may have translational importance.

Developmental Immunotoxicity, Perinatal Programming, and Noncommunicable Diseases: Focus on Human Studies

Rodney R. Dietert

Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University,

Advances in Medicine Volume 2014

Developmental immunotoxicity (DIT) is a term given to encompass the environmentally induced disruption of normal immune development resulting in adverse outcomes. A myriad of chemical, physical, and psychological factors can all contribute to DIT. As a core component of the developmental origins of adult disease, DIT is interlinked with three important concepts surrounding health risks across a lifetime: (1) the Barker Hypothesis, which connects prenatal development to later-life diseases, (2) the hygiene hypothesis, which connects newborns and infants to risk of later-life diseases and, (3) fetal programming and epigenetic alterations, which may exert effects both in later life and across future generations. Risk factors considered in this review include air pollution, aluminum , antibiotics, arsenic, bisphenol A, ethanol, lead (Pb), maternal smoking and environmental tobacco smoke, paracetamol (acetaminophen), pesticides, polychlorinated biphenyls, and polyfluorinated compounds.

QUOTE: There is evidence to suggest that febrile responses in children following alum-containing vaccination may represent an inflammation-driven hyperresponse that occurs in a subset of children, possibly those possessing certain cytokine gene alleles [86]. A proposed mechanistic basis for alum-induction of DIT in a subpopulation of children was discussed by Terhune and Deth [87]. These authors suggested that the Th2 biasing and inflammasome activating effects of aluminum may present a problem for children carrying genetic variants of certain cytokine genes (e.g., IL-4, IL- 13, IL-33, and IL-18). In some subpopulations of children, aluminum adjuvants might enhance the production of non- target directed IgE thereby elevating the risk of allergy and atopy [87]. Other investigators have suggested that alum may play a role in the induction of Crohn’s disease in genetically susceptible individuals [88].

Cytokines and CNS Development

Benjamin E. Deverman1 and Paul H. Patterson1,* 1Division of Biology, California Institute of Technology, 1200 East California Boulevard M/C 216-76, Pasadena, CA 91125, USA

Neuron 64, October 15, 2009

Cytokines are pleotrophic proteins that coordinate the host response to infection as well as mediate normal, ongoing signaling between cells of nonimmune tissues, including the nervous system. As a consequence of this dual role, cytokines induced in response to maternal infection or prenatal hypoxia can profoundly impact fetal neurodevelopment. The neurodevelopmental roles of individual cytokine signaling pathways are being elucidated through gain- and loss-of-function studies in cell culture and model organisms. We review this work with a particular emphasis on studies where cytokines, their receptors, or components of their signaling pathways have been altered in vivo. The extensive and diverse requirements for properly regulated cytokine signaling during normal nervous system development revealed by these studies sets the foundation for ongoing and future work aimed at understanding how cytokines induced normally and pathologically during critical stages of fetal development alter nervous system function and behavior later in life.

Cytokine-dependent bidirectional connection between impaired social behavior and susceptibility to seizures associated with maternal immune activation in mice

James Washington III et al

Department of Pediatrics, David Geffen School of Medicine at UCLA,

Epilepsy & Behavior 50 (2015)

Maternal immune activation (MIA) results in the development of autism in the offspring via hyperactivation of IL-6 signaling. Furthermore, experimental studies showed that the MIA-associated activation of interleukin-1β (IL-1β) concurrently with IL-6 increases the rate and the severity of hippocampal kindling in mice, thus, offering an explanation for autism–epilepsy comorbidity. We examined whether epileptic phenotype triggered by prena- tal exposure to IL-6 and IL-1β combination is restricted to kindling or whether it is reproducible in another model of epilepsy, whereby spontaneous seizures develop following kainic acid (KA)-induced status epilepticus. We also examined whether in mice prenatally exposed to IL-6 and IL-6 + IL-1β, the presence of spontaneous seizures would exacerbate autism-like features. Between days 12 and 16 of pregnancy, C57BL/6J mice received daily in- jections of IL-6, IL-1β, or IL-6 + IL-1β combination. At postnatal day 40, male offspring were examined for the presence of social behavioral deficit, and status epilepticus was induced by intrahippocampal KA injection. After 6 weeks of monitoring for spontaneous seizures, sociability was tested again. Both IL-6 and IL-6 + IL-1β offspring presented with social behavioral deficit. Prenatal exposure to IL-6 alleviated, while such exposure to IL- 6 + IL-1β exacerbated, the severity of KA-induced epilepsy. Increased severity of epilepsy in the IL-6 + IL-1β mice correlated with the improvement of autism-like behavior. We conclude that complex and not necessarily agonistic relationships exist between epileptic and autism-like phenotypes in an animal model of MIA coupled with KA-induced epilepsy and that the nature of these relationships depends on components of MIA involved.

Cytokine dysregulation in autism spectrum disorders (ASD): Possible role of the environment

Paula E. Goines a, Paul Ashwood b,⁎

Neurotoxicology and Teratology xxx (2012)

Autism spectrum disorders (ASD) are neurodevelopmental diseases that affect an alarming number of individuals. The etiological basis of ASD is unclear, and evidence suggests it involves both genetic and environmental factors. There are many reports of cytokine imbalances in ASD. These imbalances could have a pathogenic role, or they may be markers of underlying genetic and environmental influences. Cytokines act primarily as mediators of immunological activity but they also have significant interactions with the nervous system. They participate in normal neural development and function, and inappropriate activity can have a variety of neurological implications. It is therefore possible that cytokine dysregulation contributes directly to neural dysfunction in ASD. Further, cytokine profiles change dramatically in the face of infection, disease, and toxic exposures. Imbalances in cytokines may represent an immune response to environmental contributors to ASD. The following review is presented in two main parts. First, we discuss select cytokines implicat- ed in ASD, including IL-1Β, IL-6, IL-4, IFN-γ, and TGF-Β, and focus on their role in the nervous system. Second, we explore several neurotoxic environmental factors that may be involved in the disorders, and focus on their immunological impacts. This review represents an emerging model that recognizes the importance of both genetic and environmental factors in ASD etiology. We propose that the immune system provides critical clues regarding the nature of the gene by environment interactions that underlie ASD pathophysiology.

Cytokine aberrations in autism spectrum disorder: a systematicreview and meta-analysis

A Masi1, DS Quintana1, N Glozier1, AR Lloyd2, IB Hickie1 and AJ Guastella1

Molecular Psychiatry (2014)

The role of non-diagnostic features in the pathophysiology of autism spectrum disorders (ASDs) is unclear. Increasing evidence suggests immune system alterations in ASD may be implicated in the severity of behavioral impairment and other developmental outcomes. The primary objective of this meta-analysis was to investigate if there is a characteristic abnormal cytokine profile in ASD compared with healthy controls (HCs). We identified relevant studies following a search of MEDLINE, EMBASE, PsycINFO, Web of Knowledge and Scopus. A meta-analysis was performed on studies comparing plasma and serum concentrations of cytokines in unmedicated participants with ASD and HCs. Results were reported according to PRISMA statement. Seventeen studies with a total sample size of 743 participants with ASD and 592 HC were included in the analysis. Nineteen cytokines were assessed. Concentrations of interleukin (IL)-1beta (P o 0.001), IL-6 (P = 0.03), IL-8 (P = 0.04), interferon-gamma (P = 0.02), eotaxin (P = 0.01) and monocyte chemotactic protein-1 (Po0.05) were significantly higher in the participants with ASD compared with the HC group, while concentrations of transforming growth factor-β1 were significantly lower (Po0.001). There were no significant differences between ASD participants and controls for the other 12 cytokines analyzed. The findings of our meta-analysis identified significantly altered concentrations of cytokines in ASD compared to HCs, strengthening evidence of an abnormal cytokine profile in ASD where inflammatory signals dominate.

Brain-Derived Neurotrophic Factor and Interleukin-6 Levels in the Serum and Cerebrospinal Fluid of Children with Viral Infection-Induced Encephalopathy

Shinichiro Morichi

Neurochem Res (2014)August 2014

We investigated changes in the brain-derived neurotrophic factor (BDNF) and interleukin (IL)-6 levels in pediatric patients with central nervous system (CNS) infec- tions, particularly viral infection-induced encephalopathy. Over a 5-year study period, 24 children hospitalized with encephalopathy were grouped based on their acute encepha- lopathy type (the excitotoxicity, cytokine storm, and meta- bolic error types). Children without CNS infections served as controls. In serum and cerebrospinal fluid (CSF) samples, BDNF and IL-6 levels were increased in all encephalopathy groups, and significant increases were noted in the influenza- associated and cytokine storm encephalopathy groups. Children with sequelae showed higher BDNF and IL-6 levels than those without sequelae. In pediatric patients, changes in serum and CSF BDNF and IL-6 levels may serve as a prognostic index of CNS infections, particularly for the diagnosis of encephalopathy and differentiation of encephalopathy types.

NOTE: Shows association between neurological damage and elevated IL-6 in humans.

Brain Region–Specific Alterations in the Gene Expression of Cytokines, Immune Cell Markers and Cholinergic System Components during Peripheral Endotoxin–Induced Inflammation

Harold A Silverman,

MOLECULAR MEDICINE 20:601-611, 2014

Inflammatory conditions characterized by excessive peripheral immune responses are associated with diverse alterations in brain function, and brain-derived neural pathways regulate peripheral inflammation. Important aspects of this bidirectional peripheral immune–brain communication, including the impact of peripheral inflammation on brain region–specific cytokine responses, and brain cholinergic signaling (which plays a role in controlling peripheral cytokine levels), remain unclear. To provide insight, we studied gene expression of cytokines, immune cell markers and brain cholinergic system components in the cortex, cerebellum, brainstem, hippocampus, hypothalamus, striatum and thalamus in mice after an intraperitoneal lipopolysaccharide injection. Endotoxemia was accompanied by elevated serum levels of interleukin (IL)-1â, IL-6 and other cytokines and brain region–specific increases in Il1b (the highest increase, relative to basal level, was in cortex; the lowest increase was in cerebellum) and Il6 (highest increase in cerebellum; lowest increase in striatum) mRNA expression. Gene expression of brain Gfap (astrocyte marker) was also differentially increased. However, Iba1 (microglia marker) mRNA expression was decreased in the cortex, hippocampus and other brain regions in parallel with morphological changes, indicating microglia activation. Brain choline acetyltransferase (Chat ) mRNA expression was decreased in the striatum, acetylcholinesterase (Ache) mRNA expression was decreased in the cortex and increased in the hip- pocampus, and M1 muscarinic acetylcholine receptor (Chrm1) mRNA expression was decreased in the cortex and the brainstem. These results reveal a previously unrecognized regional specificity in brain immunoregulatory and cholinergic system gene expression in the context of peripheral inflammation and are of interest for designing future antiinflammatory approaches.

QUOTE: Dysregulated peripheral immune responses and cytokine release mediate pathogenesis in sepsis, type 2 diabetes, rheumatoid arthritis, lupus and other inflammatory and autoimmune conditions (1–4). Peripherally released cytokines and other inflammatory molecules have also been associated with brain immune activation and altered brain neuronal function in these disorders (5–13). Peripheral inflammation and elevated systemic cytokine levels have been proposed to contribute to brain inflammation and pathogenesis in Alzheimer’s disease (14,15), Parkinson’s disease (16) and schizophrenia (17).

Fetal Inflammatory Response and Brain Injury in the Preterm Newborn

Shadi Malaeb, MD and Olaf Dammann, MD Division of Newborn Medicine, Floating Hospital for Children at Tufts Medical Center, Boston, Massachusetts (SM, OD) and the Perinatal Neuroepidemiology Unit, Hannover Medical School, Hannover, Germany (OD)

Child Neurol. 2009 September ; 24(9): 1119–1126.

Preterm birth can be caused by intrauterine infection and maternal/fetal inflammatory responses. Maternal inflammation (chorioamnionitis) is often followed by a systemic fetal inflammatory response characterized by elevated levels of pro-inflammatory cytokines in the fetal circulation. The inflammation signal is likely transmitted across the blood-brain barrier, and initiates a neuroinflammatory response. Microglial activation has a central role in this process, and triggers excitotoxic, inflammatory, and oxidative damage in the developing brain. Neuroinflammation can persist over a period of time and sensitize the brain to subinjurious insults in early and chronic phases, but may offer relative tolerance in the intermediate period through activation of endogenous anti-inflammatory, protective, and repair mechanisms. Neuroinflammatory injury not only destroys what exists, but also changes what develops.

Modeling an autism risk factor in mice leads to permanent immune dysregulation

Elaine Y. Hsiao1, Sara W. McBride, Janet Chow, Sarkis K. Mazmanian, and Paul H. Patterson

Biology Division, California Institute of Technology, Pasadena, CA 91125 Edited by Carla J. Shatz, Stanford University, Stanford, CA, and approved June 19, 2012

Increasing evidence highlights a role for the immune system in the pathogenesis of autism spectrum disorder (ASD), as immune dysregulation is observed in the brain, periphery, and gastroin- testinal tract of ASD individuals. Furthermore, maternal infection (maternal immune activation, MIA) is a risk factor for ASD. Modeling this risk factor in mice yields offspring with the cardinal behavioral and neuropathological symptoms of human ASD. In this study, we find that offspring of immune-activated mothers display altered immune profiles and function, characterized by a systemic deficit in CD4+ TCRβ+ Foxp3+ CD25+ T regulatory cells, increased IL-6 and IL-17 production by CD4+ T cells, and elevated levels of peripheral Gr-1+ cells. In addition, hematopoietic stem cells from MIA offspring exhibit altered myeloid lineage potential and differentiation. Interestingly, repopulating irradiated control mice with bone marrow derived from MIA offspring does not con- fer MIA-related immunological deficits, implicating the peripheral environmental context in long-term programming of immune dys- function. Furthermore, behaviorally abnormal MIA offspring that have been irradiated and transplanted with immunologically nor- mal bone marrow from either MIA or control offspring no longer exhibit deficits in stereotyped/repetitive and anxiety-like behav- iors, suggesting that immune abnormalities in MIA offspring can contribute to ASD-related behaviors. These studies support a link between cellular immune dysregulation and ASD-related behavioral deficits in a mouse model of an autism risk factor.

Altered nociceptive, endocrine, and dorsal horn neuron responses in rats following a neonatal immune challenge

Ihssane Zouikra, Melissa A. Tadrosb, Javad Baroueia, Kenneth W. Beagley c, Vicki L. Clifton d, Robert J. Callister b, Deborah M. Hodgson a,*

Laboratory of Neuroimmunology, School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia

Psychoneuroendocrinology (2014) 41, 1—12

The neonatal period is characterized by significant plasticity where the immune, endocrine, and nociceptive systems undergo fine-tuning and maturation. Painful experiences during this period can result in long-term alterations in the neurocircuitry underlying nociception, including increased sensitivity to mechanical or thermal stimuli. Less is known about the impact of neonatal exposure to mild inflammatory stimuli, such as lipopolysaccharide (LPS), on subsequent inflammatory pain responses. Here we examine the impact of neonatal LPS exposure on inflammatory pain sensitivity and HPA axis activity during the first three postnatal weeks. Wistar rats were injected with LPS (0.05 mg/kg IP, Salmonella enteritidis) or saline on postnatal days (PNDs) 3 and 5 and later subjected to the formalin test at PNDs 7, 13, and 22. One hour after formalin injection, blood was collected to assess corticosterone responses. Transverse spinal cord slices were also prepared for whole-cell patch clamp recording from lumbar superficial dorsal horn neurons (SDH). Brains were obtained at PND 22 and the hypothalamus was isolated to measure glucocorticoid (GR) and mineralocorticoid receptor (MR) transcript expression using qRT-PCR. Behavioural analyses indicate that at PND 7, no significant differences were observed between saline- or LPS-challenged rats. At PND 13, LPS-challenged rats exhibited enhanced licking ( p < .01), and at PND 22, increased flinching in response to formalin injection ( p < .05). LPS- challenged rats also displayed increased plasma corticosterone at PND 7 and PND 22 ( p < .001)

Altered neural connectivity in excitatory and inhibitory cortical circuits in autism

Basilis Zikopoulos* and Helen Barbas

Neural Systems Laboratory, Department of Health Sciences, Boston University, Boston, MA,

Frontiers in Human Neuroscience September 2013 | Volume 7 | Article 609 |

Converging evidence from diverse studies suggests that atypical brain connectivity in autism affects in distinct ways short- and long-range cortical pathways, disrupting neural communication and the balance of excitation and inhibition. This hypothesis is based mostly on functional non-invasive studies that show atypical synchronization and connectivity patterns between cortical areas in children and adults with autism. Indirect methods to study the course and integrity of major brain pathways at low resolution show changes in fractional anisotropy (FA) or diffusivity of the white matter in autism. Findings in post-mortem brains of adults with autism provide evidence of changes in the fine structure of axons below prefrontal cortices, which communicate over short- or long-range pathways with other cortices and subcortical structures. Here we focus on evidence of cellular and axon features that likely underlie the changes in short- and long-range communication in autism. We review recent findings of changes in the shape, thickness, and volume of brain areas, cytoarchitecture, neuronal morphology, cellular elements, and structural and neurochemical features of individual axons in the white matter, where pathology is evident even in gross images. We relate cel