Activation of TLR4 pathways is involved in the elevated expression of BAFF receptor, BR3, in peripheral monocytes of patients with Sjögren’s syndrome 2399

Abstract Description Background and Purpose: We reported that the elevated expression of BAFF receptor, BR3, in peripheral monocytes of patients with Sjögren’s syndrome (SS) is correlated with clinical parameters of the patients. We found that TLR4 ligands enhanced the BR3 expression in human monocytic cell line, THP-1. In this study, we investigated the possible involvement of TLR4 pathways in the expression of BR3 in peripheral SS monocytes. Methods The expression levels of CD14, CD16, BR3 and TLR4 in peripheral monocytes from SS patients (n = 71) and healthy controls (HC; n = 23) were analyzed by FACS. PBMCs were stimulated with TLR4 ligands, such as LPS or S100A9, and the expression level of BR3 in the cells and the amount of IL-6 in the culture supernatants were analyzed by FACS and ELISA, respectively. The serum level of S100A9 was measured by ELISA. Results The expression levels of TLR4 and BR3 in CD14 ++CD16+ cells (intermediate monocytes, IM) were significantly higher in SS than HC. The expression level of TLR4 was significantly and positively correlated with that of BR3 in SS IM. Notably, TLR4 ligands enhanced the BR3 expression and IL-6 production of peripheral monocytes in vitro. Moreover, the serum level of S100A9 was significantly higher in SS than HC, and significantly correlated with the proportion of TLR4+ cells among SS IM. Conclusion Our results collectively suggest that activation of TLR4 signaling pathways contributes to the elevated expression of BR3 in SS monocytes. Topic Categories Cytokines and Chemokines and Their Receptors (CCR)