B Cells Play Significant Role in Multiple Sclerosis Disease Progression

B cell depletion therapy decreases new disease activity in people with relapsing-remitting MS.

Modern science points to T cells as the culprits behind multiple sclerosis (MS).

Research has shown that in MS, T cells inappropriately attack myelin, the protective layer of fat covering the nerves in the central nervous system, damaging them.

Another type of white blood cell called B cells may also play a significant role in contributing to the disease. Investigators previously reported that B cell depletion therapy (BCDT) in people with relapsing-remitting MS led to dramatic decreases in new disease activity, suggesting that B cells play a significant role in disease progression.

But exactly how it functions in contributing to the disease and the molecular mechanisms involved in the benefit of BCDT remains elusive, the results of a recent study indicate.

“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,” said senior author Dr. Amit Bar-Or, director of the Experimental Therapeutics Program and scientific director of the Clinical Research Unit at the Montreal Neurological Institute.

In examining samples of MS patients to compare them with healthy subjects, the study authors discovered that GM-CSF producing B cells were more frequent and more prone to activation in MS patients. The subset of B cells was able to activate pro-inflammatory responses of myeloid cells of the immune system.

Researchers found that after completion of BCDT, myeloid cells became less pro-inflammatory, suggesting a connection between BCDT and decreasing the number of 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,” the authors wrote. “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.”

There is currently no cure for MS, but this study holds promise for the development of the next generation of targeted therapies that could one day provide hope for the debilitating disease.