The Connection Between Beneficial Gut Bacteria and Rheumatoid Arthritis Unveiled

Recent research has shed light on the complex relationship between the microbiome—the community of microorganisms living in our gut—and autoimmune diseases like rheumatoid arthritis (RA). Scientists have discovered that beneficial, or 'good,' bacteria in the gut play a crucial role in influencing immune system behavior, particularly through a type of immune cell known as T follicular helper 17 (T_FH17) cells.

Historically, commensal bacteria, which coexist harmlessly within our intestines, were thought to support health without causing issues. However, studies dating back to 2016 revealed that certain gut microbes could unexpectedly trigger immune responses that lead to systemic autoimmune conditions. This discovery focused attention on T cells’ remarkable ability to adapt and respond to environmental signals—a trait called plasticity—which enables them to change their function in response to stimuli.

In the gut, T helper cells can reprogram themselves, transforming into hybrid cells that possess properties of both T_FH and T_H17 cells. These reprogrammed cells, especially when influenced by bacteria such as segmented filamentous bacteria, can travel from the intestine to other parts of the body. Scientists observed this migration using advanced tracking techniques in mouse models.

Once they reach systemic circulation, these hyperactive T_FH17 cells can excessively stimulate B cells, leading to increased production of autoantibodies that damage joints and tissues characteristic of RA. The presence of these abnormal cells in mice closely resembles the gene expression profiles seen in humans with rheumatoid arthritis, indicating similar pathogenic mechanisms.

Experimental manipulations demonstrated that introducing these T_FH17 cells into mouse models heightened the severity of arthritis, highlighting their critical role in disease progression. These findings suggest that targeting these cells or their formation could offer new therapeutic strategies for RA and potentially other autoimmune diseases.

In summary, this research reveals how certain beneficial gut bacteria can inadvertently foster immune cell changes that promote systemic autoimmunity. Understanding this relationship opens avenues for novel treatments aimed at modulating gut microbiota or immune cell reprogramming to combat autoimmune conditions.

Published in Nature Immunology, this study provides significant insight into the microbiome-immune system connection and its impact on diseases like rheumatoid arthritis.

source: https://medicalxpress.com/news/2025-05-link-good-gut-bacteria-rheumatoid.html