Short-chain fatty acids, like PA, are processed from indigestible dietary fibers by gut bacteria. ​​​​​​PA is often used as a preservative and can be found in foods like cheeses, baked goods, or additives for artificial fruit flavors.

Propionic acid (PA), a short-chain fatty acid, influences the multiple sclerosis ( MS ) disease course by an immunomodulatory mechanism, according to a study published in Cell.

Patients with MS have reduced PA, which is associated with an altered gut microbiome composition. The deficiency is most notable in the earliest phases of the disease. In a proof-of-concept study, researchers supplemented PA to therapy-naïve patients as an add-on to MS immunotherapy.

“After 2 weeks of PA intake, we observed a significant and sustained increase of functionally competent regulatory T (Treg) cells, whereas Th1 and Th17 cells decreased significantly,” researchers said. T cells located in the gut work to stop excessive inflammatory processes and reduce autoimmune cells in diseases like MS.

Additional results included:

A reduced annual relapse rate, disability stabilization, and reduced brain atrophy after 3 years of PA intake

Increased expression of Treg-cell-inducing genes in the intestine after PA intake

PA normalized Treg cell mitochondrial function and morphology in MS

Interactions among dietary components, microbiota, metabolites and the immune system all take place within the intestinal wall of the gut. “This is how intestinal bacteria can directly and indirectly affect anatomically distant structures such as the brain,” said Aiden Haghikia, PhD, an author of the study. “Accordingly, the gut microbiome acts like a self-sufficient endocrine organ that interacts with the environment.”

Researchers note that associated changes in the gut microbiome play an important role in differentiating regulatory cells. “The increased function of these cells was due to their improved energy utilisation through an altered function of the mitochondria.”

Authors hope the study opens up opportunities to investigate additional metabolites of intestinal bacteria generated from one’s diet. “Further research into this largely unknown organ and the knowledge gained from it will enable us to develop innovative dietary measures to complement the known therapeutics in the future,” said Haghikia.

Reference

Duscha A, Gisevius B, Hirschberg S, et al. Propionic acid shapes the multiple sclerosis disease course by an immunomodulatory mechanism [published online March 10, 2020]. Cell. doi: 10.1016/j.cell.2020.02.035.