New research from the Mount Sinai Medical Center suggests that being extremely sensitive to stress may increase your susceptibility to depression. At least in mice.

Mice whose immune systems responded to stress by overproducing an inflammatory compound called interleukin-6 were more likely to become depressed.

Typically interleukin-6 is released by white blood cells in response to injury. The compound is also found in elevated levels in people with treatment-resistant depression.

The research was led by Georgia Hodes, PhD, a postdoctoral fellow in the Department of Neuroscience at Mount Sinai.

Hodes noted that stress could be thought of as an allergen, like pet dander, with the over-reactive immune system making a person susceptible to it more likely to be depressed.

The researchers found no evidence of interleukin-6 being made in the brain areas examined, suggesting that it is released in the peripheral immune system.

So the Mount Sinai team transplanted the bone marrow of depressed mice into healthy mice and found that these previously healthy mice exhibited signs of depression after experiencing a mild stressor.

They also found that mice with immune cells that release more interleukin-6 in response to a toxin developed a more severe depression-like response to the stress.

“To our knowledge, this is the first study showing a functional role for the peripheral immune system in an animal model of depression,” said Dr. Hodes.

“This study suggests that cytokine-based antibody therapy currently approved for treatment of inflammatory illnesses such as rheumatoid arthritis and Castleman’s disease in humans may have potential as an antidepressant treatment.”

“In some ways, it is an analogy to an allergy,” Dr. Hodes told a news organization.

“You have something that is not really dangerous, but your body thinks it is, so you have this massive immune response. In this case, the stressor is what they’re having this massive immune response to.”

Some of the drugs used in the study to dampen that immune response are already on the market to treat rheumatoid arthritis in humans, Hodes said.

The researchers are now working with mice genetically altered not to produce IL-6 to investigate whether those animals can be used as bone marrow donors to cure stress-susceptible mice.

Source: News wires

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