EBV and CMV viral load in rheumatoid arthritis and their role in associated Sjögren's syndrome

Introduction The role of viral infections in the pathogenesis of autoimmune diseases has long been suggested, but little evidence is available. Objective This study aimed to evaluate an association between EBV and CMV and the presence of rheumatoid arthritis and its association with Sjögren's Syndrome. Patients and Method A case‐control study was performed with 227 patients divided in RA (n = 99), RA/SS (n = 20), and C (n = 128). Resting salivary flow rate and Schirmer's test were performed; minor salivary gland biopsy was indicated in the case of suspected Sjögren's syndrome. CMV and EBV viral loads were quantified in peripheral blood, and their presence in glandular tissue samples was evaluated by in situ hybridization (EBV) and immunohistochemistry (CMV). Results EBV was more frequent in RA and RA/SS than in C (P .05) or between RA and RA/SS was found (P > .05). A higher number of EBV/DNA copies were found in RA (158.52 copies/μL) and RA/SS (99.24 copies/μL) (P = .739). EBV/DNA was associated with the Schirmer test (P = .0231). CMV was detected in one patient of the RA group. None of the viruses were detected in biopsies of minor salivary glands. Conclusions Detection of EBV/DNA in peripheral blood was associated with RA regardless of the presence of SS.