S100A8/A9 promotes dendritic cell-mediated Th17 cell response in SS dry eye

Sjogren's syndrome (SS) dry eye is a chronic autoimmune eyedisease driven by T helper 17 (Th17)cells. S100A8/A9 has emerged as an important proinflammatory alarmin in variousautoimmune and inflammatory diseases. However, the role of S100A8/A9 in the pathogenesis of SS dry eye remains unexplored. Here,we show that the expression levels of S100A8/A9 were elevated in peripheral blood mononuclear cells (PBMCs) of patients with SS dry eye, as well as the lacrimal glands (LGs) of SS dry eye mice. The administration of paquinimod, a specific inhibitor of S100A8/A9, could alleviate the progression of SS dry eye with significant reduction of Th17 cell frequency in LGs, spleen and lymph nodes of SS dry eye mice.Further experiment revealed that S100A8/A9 did not directly affect Th17 generation and function, but upregulated the expression of MHCIl andI123a in DCs to augment Th17 cell response through a Acod1/STAT3-dependent signaling pathway in the context of SS dry eye. Together,these findings unveiled the key role of S100A8/A9 in the pathogenesis of SS dry eye and suggested a potential therapeutic avenue for SS dry eyeand otherTh7 cell-related autoimmune disorders. We isolated bone marrow cells from SS dry eye mice to induce DCs, and stimulated DCs with recombinant S100A8/A9 or Vehicle. Total RNAs of Vehicle- or S100A8/A9-treated DCs were extracted using TRIzol® Reagent (Invitrogen). Then RNA‐sequencing was performed to predict downstream signaling pathways involved in the regulatory effect of S100A8/A9 on DCs.