Exploring the association between Mycobacterium avium subspecies paratuberculosis infection and rheumatoid arthritis: an immunological perspective

Mycobacterium avium subspecies Paratuberculosis (MAP) is a bacterium known to cause Johne's disease in ruminants and has been implicated in several autoimmune diseases. This study aimed to investigate the potential association between MAP infection and Rheumatoid Arthritis (RA). A total of 119 patients with RA and 120 healthy controls (HCs) were enrolled in the study. The participants were outpatient attendees at a rheumatology specialist's clinic, selected according to the 2010 ACR/EULAR Classification Criteria for RA. Their serum samples were analyzed for antibodies against two peptides, MAP_402718–32 and IRF5424-434, using an indirect enzyme-linked immunosorbent assay (ELISA). A significant difference was found in the levels of anti-MAP antibodies between RA patients and HCs. RA patients were more likely to have anti-MAP_402718–32 antibodies (44.5%) vs. 10.8% in HCs. Among RA patients, treatment group patients had more antibodies (51.6%) against MAP_402718–32 than no-treatment group patients (36.4%), but this difference was not statistically significant. The antigen IRF5424-434 showed the highest antibody seroreactivity, being present in a higher percentage of RA patients (60.5%) compared to HCs (8.3%). This difference was statistically significant. There was a moderate correlation between IRF5424-434 and its MAP_402718-32 homolog. The study findings suggest that anti-MAP antibodies are more prevalent in RA patients compared to healthy controls, potentially implicating MAP in the development of RA. The strong immunological response to the antigen IRF5424-434 warrants further investigation. Although the difference in antibody levels between previously diagnosed and newly diagnosed RA patients was not statistically significant, the overall higher prevalence of these antibodies in the RA cohort supports the hypothesis of MAP's involvement.