Reatividade sorológica anti-toxocara em doenças reumáticas autoimunes revela supressão seletiva de IgG4 no lúpus eritematoso sistêmico

Abstract

Helminth exposure has been suggested as a modulating factor in autoimmune inflammation; however, gaps remain regarding the quality of anti-helminth immune responses in autoimmune rheumatic diseases. In this study, we analyzed anti-Toxocara canis seroreactivity profiles in individuals with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and spondyloarthritis (SpA), compared with controls, and also investigated potential clinical associations. A cross-sectional case-control study was conducted, including 442 participants. Initially, samples were tested for anti -T. canis IgG using native TES antigen, and reactive samples were subsequently evaluated using the recombinant chimeric antigen rSHORT for the detection of total IgG, IgG1, and IgG4. Disease activity was assessed using SLEDAI in SLE, and functional disability using HAQ-DI. The results demonstrated a high frequency of anti-T. canis seroreactivity in the studied population. After adjustment for demographic variables, patients with SLE showed higher odds of total IgG positivity compared with controls, whereas IgG4 seroreactivity was significantly reduced. No independent associations were observed between IgG isotypes and HAQ-DI in patients with RA or SpA. Within the SLE group, higher eosinophil levels were independently associated with lower disease activity. Overall, these findings indicate heterogeneous patterns of anti-Toxocara serological responses in autoimmune rheumatic diseases, with SLE showing the most distinctive profile, characterized by preserved total IgG responses alongside reduced IgG4 seroreactivity. Furthermore, eosinophils, rather than IgG4, were more strongly associated with lower disease activity in SLE.