Researchers have new evidence suggesting that microorganisms responsible for chronic inflammatory gingival infections may also trigger rheumatoid arthritis (RA). The latest research from Johns Hopkins University School of Medicine in Baltimore has implications for the prevention and treatment of RA. The findings point to Aggregatibacter actinomycetemcomitans as causing a cascade of inflammatory events. Published in Science Translational Medicine, the study, “Aggregatibacter actinomycetemcomitans-induced Hypercitrullination Links Periodontal Infection to Autoimmunity in Rheumatoid Arthritis,” leads scientists that much closer to uncovering the root cause of RA.
Periodontal disease and RA may be closely associated, as researchers postulate that common factors may link these conditions. The Johns Hopkins team discovered that a process found in the joints of patients with RA — hypercitrullination, which regulates protein function — was also noted in the gingiva of patients with periodontitis. Although this is a natural process, it becomes overactive in patients with RA, resulting in citrullinated proteins that drive production of inflammatory-inducing antibodies that attack tissues.
The exploration reveals that A. actinomycetemcomitans is the only pathogen capable of inducing hypercitrullination in neutrophils — which are the most abundant inflammatory cells in the joints and gingiva of individuals with RA and/or periodontitis. Furthermore, exposure to the pathogen is a major determinant in the production of antibodies to citrullinated proteins in patients with genetic susceptibility to RA. Although investigators were able to pinpoint the pathogen’s role in the onset of RA and periodontal disease, these findings focus on subjects examined at one point in time. The researchers assert that proving a cause-and-effect relationship will require additional long-term research.