Association of Plasmacytoid Dendritic Cells with B Cell Infiltration in Minor Salivary Glands in Patients with Sjögren's Syndrome

<b><i>Objectives:</i></b>Sjogren’s syndrome (SS) is an autoimmune disease with features of both over-production of specific autoantibodies and organ-specific disorders, mainly sialadenitis and dacryoadenitis. However, little is known about the factors that contribute to lymphocytic infiltration of SS.<b><i>Methods:</i></b>Minor salivary gland (MSG) tissue was obtained from 83 patients with primary SS (pSS) and 95 patients with secondary SS and examined pathologically, and correlation between infiltrated immune cells and histological features was evaluated.<b><i>Results:</i></b> Plasmacytoid dendritic cells (pDCs) were increased in MSG of SS compared to Sicca syndrome. The density of pDCs was characteristically correlated with the accumulation of CXCL13⁺CD68⁺ macrophages and CXCR5⁺CD19⁺ B in the MSG of pSS. In vitro analysis indicated that Type I interferon (IFN) enhanced CXCL13 production by macrophages. Type I IFN was mainly expressed in pDCs and its expression was correlated with the accumulation of CXCL13⁺ macrophages in the MSG of pSS.<b><i>Conclusions:</i></b>Our histological findings suggest the possible mechanism of type I IFN-CXCL13 axis during the pathological processes of acute/chronic salivary inflammation in SS; local production of type I IFN by pDCs, induction of CXCL13 production in macrophages by type I IFN, induction of accumulation of CXCR5⁺CD19⁺ B cells by CXCL13 in the MSG.