Researchers at the University of Toronto and UC San Francisco have discovered that the intestine is the source of immune cells that reduce brain inflammation in people with multiple sclerosis (MS), and that increasing the number of these cells blocks inflammation entirely in a preclinical model of the disease.
The cells in question are plasma cells — white blood cells that originate as B cells in the bone marrow but change their behavior when triggered by microbes in the gut. Studying mice and samples from human MS patients, the researchers found that plasma cells that reside in the gut and produce Immunoglobulin A (IgA) antibodies appear to migrate to the central nervous system and produce an anti-inflammatory effect during MS flare-ups.
MS is an autoimmune disease, driven by other types of immune cells (including B and T cells) that attack myelin, the protective coating that surrounds nerve fibers. Recent clinical studies have shown drugs that target B cells mitigate MS, while those that target plasma cells make the disease worse. The current study offers an explanation for these divergent results.