Study suggests bacterial products contribute to autoimmune diseases

November 04, 2017

Additionally, researchers found that mouth samples of participants with RA exhibited an overabundance of the porphyromonas genus compared to healthy controls. To examine bacteria in the mouth, researchers studied the gums of participants with RA or psoriatic arthritis, and healthy individuals. When examining the gums of these participants, researchers noted that 78 percent of the examined sites bled during examination in participants with RA, which was a significantly higher percentage than those with psoriatic arthritis (38 percent) and those participants identified as healthy (12 percent). Overall, 66 percent of participants with RA had moderate gum disease - compared to 25 percent of the participants with psoriatic arthritis and 12 percent of the participants in the healthy group.

Additional studies by the group have demonstrated that specific microbes induce the differentiation of Th17 cells in the intestine. There is already strong genetic and therapy-based evidence that pro-inflammatory Th17 cells and anti-inflammatory regulatory T cells (Treg) have critical roles in autoimmune diseases, including RA, psoriatic arthritis, and Crohn's disease.

"The basic premise is that there are different oral and gut bacteria that activate Th17 cells to promote inflammation," Dr. Scher explains. "Our hypotheses are that characterization of Th17-inducing microbes in the human intestine will provide insight into disease pathogenesis, and that directed manipulation of the gut microbiota will result in the alteration of arthritis biomarkers, including Th17/Treg balance."

The next step for the team is a study in which 90 participants with RA will be subdivided into three arms. The first two arms will be given antibiotics for a two-month period, and the third arm will be given placebo. The researchers believe that by modifying the microbial flora with antibiotics, they can identify molecular mechanisms by which RA-associated bacteria affect Th17 and Treg homeostasis and thereby develop new strategies to diminish or even prevent the inflammatory process that leads to chronic destructive arthritis.

Source: The American College of Rheumatology