According to a recent Swiss study, a specific class of immune cells plays a central role in a newly identified gut-brain axis in patients with multiple sclerosis.
MS and the intestinal microbiota
The intestinal flora, also called intestinal microflora or intestinal microbiota, is a collection of microorganisms found in the intestines. In recent years, scientists have become increasingly interested in it. Chronic fatigue, intestinal worms, or the effects of immunotherapy may depend on the condition of the flora. And recently, scientists have even discovered a link between intestinal flora and central nervous system inflammation in multiple sclerosis (MS).
According to their study, published December 22 in the journal Science Immunology, a specific class of immune cells may play a central role in this newly identified Gut-brain axis. Ultimately, these findings could enable the development of new treatments for MS. Multiple sclerosis is an inflammatory and degenerative disease of the brain and spinal cord that currently affects 2.5 million people worldwide.
Currently, the treatment of multiple sclerosis is based on the elimination of IgA B-cells from the patients’ blood. Immunoglobulin A (IgA) is a class of antibodies that specializes in the immune defense of the mucosa. However, a few years ago, an international team from the University of Basel and the University Hospital of Basel in Switzerland discovered that it is better not to eliminate too many B cells, with the risk of making the disease worse.
Today, when analyzing stool samples from MS patients and healthy individuals, the same researchers found that the patients have B cells that specifically target the bacteria typical of the disease. They then analyzed the role of these immune cells during acute attacks in 56 patients. They found that IgA B cells accumulate in the spinal fluid and brain tissue of patients with acute inflammatory attacks.
An anti-inflammatory effect
“Apparently, these immune cells migrate from the intestine to the sites of inflammation in the central nervous system, where they release an anti-inflammatory messenger,” explains Dr. Anne-Katrin Pröbstel, who conducted the study. This could explain why the disease worsens when these immune cells are eliminated from the blood with medication,” she continues. In this way, these cells form a bridge between the intestinal flora and the inflammatory sites in the central nervous system, thus exerting an anti-inflammatory effect.
“We knew from previous studies that the composition of the intestinal flora plays a role in multiple sclerosis. But it was not yet clear how intestinal bacteria and immune cells influence each other,” says Dr. Pröbstel.
It has not yet been determined exactly what activates IgA B-cells in multiple sclerosis and triggers their migration from the intestine to the central nervous system. “If we find the trigger, we could use it to treat MS,” explains Dr. Pröbstel. For example, scientists could target the composition of the patients’ intestinal flora to mobilize IgA B-cells as an aid against inflammation of the nervous system.
Each MS case is unique
Multiple sclerosis is an inflammatory disease that destroys myelin, causing the degeneration of nerve fibers. Each case is unique and as a result, neither the number of attacks nor the age of diagnosis can predict the future of the patient. Some forms of the disease do not produce any physical symptoms, while others progress rapidly and can cause severe disability. Eventually, some people experience only one relapse in their lives. Today, there are many treatment options that allow patients to lead satisfactory social, family, and professional lives.
Recently, however, other researchers have developed a treatment that could stop the progression of the disease and at the same time preserve the immune system, thanks to the antigens present in extracellular vesicles. Tested successfully in animals, the therapy may also work well in humans.