Multiple Sclerosis Study Pinpoints B Cell Involvement in Disease Development

A recent study published in the journal Science Translational Medicine provided new insights into the role of B cells in multiple sclerosis (MS), and points to a specific line of possible new therapies. The study is entitled “Proinflammatory GM-CSF–producing B cells in multiple sclerosis and B cell depletion therapy” and was led by researchers at McGill University in Canada.

A growing body of evidence suggests that B cells, a type of white blood cells, play a key role in MS development. In fact, studies have shown that B cell depletion therapy (BCDT) in MS patients can limit inflammation in some cases and lead to a significant decline in disease activity. However, it is not clear how B cells contribute to MS pathogenesis and the mechanism underlying the effectiveness of BCDT.

Researchers have now found that a specific subset of B cells, known to produce the cytokine granulocyte macrophage-colony stimulating factor (GM-CSF; a factor involved in the immune/inflammatory response), contribute to the pathogenesis of MS.

“We’ve recently discovered that different types of human B cells exist. Some B cells have been shown to promote inflammation, while others are actually able to limit inflammation. Our study has implicated a subset of B cells, the GM-CSF producing B cells, as a key contributor in the pro-inflammatory immune cells responses at play in MS,” explained the study’s senior author Dr. Amit Bar-Or in a news release.

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Researchers found that GM-CSF producing B cells were more frequent among MS patients in comparison to healthy individuals, and that this subset of B cells was able to activate a pro-inflammatory response. The team reported that the mechanism underlying BCDT effectiveness might be linked to a decrease in the number of pathogenic GM-CSF-producing B cells.

“The study is significant in discovering a new way by which B cells can contribute to abnormal immune responses in MS which reinforces the rationale for the use of B cell depletion therapy. Furthermore, better identifying the particular subset of B cells responsible for new disease activity, we can look forward to more selectively targeting the “bad” B cells while leaving “good” B cells intact. This is important because B cells normally play key roles in our immune system, so more selective therapies offer the prospect of decreasing the risk of impairing the patients’ immune system in the long run,” concluded Dr. Bar-Or.