Summary: Immune cells have a dual function in MS; some are beneficial while others are harmful. Researchers have discovered that a type of immune cell, called plasma cells, are found in the gut and can travel to the brain to reduce inflammation in a mouse model of MS.
Background: B cells originate in the bone marrow and to have a dual role in MS: some types of B cells are shown to slow disease progression whereas another type has been shown to have harmful inflammatory effects. Where different types of B cells originate from, and how they contribute to MS disease remain unanswered questions.
Objective: A research team, led by Dr. Jennifer Gommerman, a professor of immunology at the University of Toronto, aimed to understand the origins of a type of B cells called plasma cells and their role in MS. The results were recently published in the renowned journal, Cell.
The Results: Using an animal model of MS, the research team discovered that plasma cells found in the intestines change their behavior when they interact with microbes that reside in the gut and produce an antibody called immunoglobulin A (IgA). Based on previous studies, it is known that IgA producing plasma cells have the ability to reduce inflammation.A rupture in the intestinal walls allows these plasma cells to migrate from the gut to the brain and add to the anti-inflammatory response. To test the applicability of these findings in humans, the researchers examined the stool samples of people diagnosed with MS and found a decreased level of IgA meaning that these anti-inflammatory cells were recruited to help fight MS. Taking a step further, the researchers increased the number of IgA-positive plasma cells that were migrating from the gut to the brain to show that this approach completely eliminates brain inflammation in animal models of MS.
Comment: Overall, the researchers discovered that plasma cells that travel from the gut to the brain have the ability to reduce the inflammatory response in animal models of MS. This key finding raises important questions such as whether a certain lifestyle or specific foods can create a gut environment that would allow plasma cells to flourish and reduce inflammation in humans living with MS, or can a therapeutic approach be developed that would expand the number of plasma cells in the gut to reduce inflammation in the central nervous system.
Source:
Elliott C et al. (2018) Slowly expanding/evolving lesions as a magnetic resonance imaging marker of chronic active multiple sclerosis lesions. Multiple Sclerosis Journal. [Epub ahead of Print]