Peculiarities of immunological manifestations in patients with rheumatoid arthritis in the presence of chronic infection with <i>Helicobacter pylori</i> variant encoding cytotoxin-associated gene A

Abstract

The study aimed to evaluate the association between cyclic citrullinated peptide antibody seropositivity and chronic Helicobacter pylori (H. pylori) infection in patients with rheumatoid arthritis (RA). We examined 92 women with moderate RA activity. Serum antibodies to cyclic citrullinated peptide (antiCCP), antibodies to H. pylori (anti-H. pylori-IgG), and total antibodies to H. pylori CagA antigen (antiCagA) were determined by enzyme immunoassay; the presence of anti-CagA-IgG positivity was confirmed by immunoblot. 68.5% of RA patients were positive for anti-H. pylori-IgG, and 44.4% of patients in this group were positive for anti-CagA-IgG. All the study participants were divided into three groups: I – H. pylori seronegative (H. pylori- ); II – H. pylori positive, CagA negative (H. pylori+/CagA- ); III – H. pylori positive and CagA positive (CagA+). The anti-CCP values in RA patients with CagA+ (group III) were significantly higher not only in comparison with patients seronegative for H. pylori (p < 0.001), but also in comparison with patients from group II (H. pylori+/CagA- ) (p = 0.041). A study of the influence of the RA activity, the presence of RF and H. pylori on anti-CCP content demonstrated a small proportion of anti-CCP variability (R2 = 0.09), with a high contribution of H. pylori (beta = 0.25). The addition of the CagA(+) index (beta = 0.503) to the presented model allowed us to describe the variability of anti-CCP in almost 30% of cases (R2 = 0.29). In the group of RA patients with anti-CCP values exceeding the established threshold value of 20 U/mL (normal index), there was an increase in the proportion of patients infected with H. pylori (p < 0.001), but not the proportion of CagA-positive patients (p = 0.06). When the threshold level was increased to 60 U/mL (three times the upper limit of normal) in patients with significantly high anti-CCP, the association with positivity for CagA became significant (p = 0.005). CagA is highly immunogenic and is capable of inducing an inflammatory response in the host that goes beyond the effect of H. pylori itself. Additional experimental studies are needed to investigate possible clinical and laboratory associations that may influence the treatment tactics of CagA+ patients with RA who are seropositive for anti-citrullinated antibodies, as well as to evaluate the possible effects of therapeutic intervention aimed at the eradication of H. pylori in this group.