Dysbiotic oral microbiota in patients with Sjogren's syndrome

Sjogren's syndrome (SS) is a systemic autoimmune disorder characterized by dryness of the mouth and eyes. Lymphocytic sialadenitis is a key event for the development of SS, but its pathogenic mechanism is not clear. The aim of this study is to investigate a potential role of oral microbiota in the pathogenesis of SS. Metagenomic analysis of oral microbiota collected from healthy individuals (n = 15), drug-induced sicca patients (n = 10), and SS patients (n = 25) revealed an increased Shanon diversity in SS. Although a substantial part of the changes in the oral microbiota of SS was shared in that of drug-induced sicca, SS-specific changes were also observed. Particularly, an increase in the relative abundance of Prevotella melaninogenica (Pm) was associated with SS (Odd Ratio 5.4, p = 0.003), but not with dryness, by logistic regression analysis. In contrast to commensal oral species, Pm upregulated the expression of MHC molecules, CD80, and CD86 from human submandibular gland tumor (HSG) cells in vitro.