The higher prevalence of lacunae in the high-exposure group as revealed by MRI suggests that further MRI studies are needed into long-term neuropsychological effects induced by CS2.

Background:Semaphorin 4D (SEMA4D) / CD100, known as a subfamily of axonal guidance proteins, has also been reported to act as an immunoregulator in several infectious and inflammatory diseases [1]. Sjögren’s syndrome (SS) is a systemic autoimmune disease that primarily affects the exocrine glands by infiltrated lymphocytes resulting in dryness of mouth and eyes. IL-17 was reported to impair the integrity of tight junction barrier and attenuate the expression of aquaporin 5 (AQP5), causing salivary gland dysfunction in SS [2].Objectives:This study was aimed to evaluate the role of SEMA4D in patients with SS and investigate the effect of SEMA4D on human salivary gland epithelial cell (SGEC) and T cell.Methods:Soluble SEMA4D levels in plasma were measured by enzyme-linked immunosorbent assay (ELISA) from patients with SS, non-SS sicca and healthy controls. Immortalized human SGECs, originated from acini (NS-SV-AC) and duct (NS-SV-DC), were used to evaluate the effects of SEMA4D. CD4+T cells from human peripheral blood were isolated to determine the secretion of cytokines in response to SEMA4D. IFN-γ and IL-17 were used to determine the effects on AQP5 expression of SGEC.Results:The levels of soluble SEMA4D in plasma were increased in patients with SS (median [interquartile range]: 1221.3 [393.5] pg/mL) compared to non-SS sicca (940.2 [355.1] pg/mL,p= 0.006) or healthy controls (909.5 [108.0] pg/mL,p <0.0001). The levels of soluble SEMA4D in plasma were correlated with the levels of several autoantibodies including anti-SSA (Spearman’s rho = 0.358,p= 0.006), anti-SSB (rho = 0.350,p= 0.007), and anti-muscarinic receptor 3 (M3R) Ab (rho = 0.495,p< 0.001), and also correlated with total IgG (rho = 0.431,p= 0.002). SEMA4D-stimulated SGECs showed decreased expression of tight junctions such as occludin and Zo-1. CD4+T cells secreted IFN-γ (p= 0.025), IL-17 (p= 0.028), and IL-21 (p= 0.007) with SEMA4D stimulation. IFN-γ and IL-17 decreased AQP5 expression in SGECs.Conclusion:SEMA4D contributed to decreased expression of tight junction in SGECs. SEMA4D induced production of IFN-γ and IL-17 in CD4+T cells and these cytokine decreased AQP5 expression in SGECs.References:[1]Worzfeld T, Offermanns S. Nat Rev Drug Discov. 2014;13(8):603-21.[2]Bhattarai KR, Junjappa R, Handigund M, Kim HR, Chae HJ. Autoimmun Rev. 2018;17(4):376-90.Disclosure of Interests:None declared