SAT0024 JAK-INHIBITION WITH BARICTINIB INHIBITS ACTIVATION OF NLRP1/CASPASE1/GDMSD PYROPTOSIS PATHWAY IN RHEUMATOID ARTHRITIS SYNOVIAL FIBROBLASTS

W. Xie, Z. Zhang
2020 Annals of the Rheumatic Diseases  
Background:Synovial fibroblasts (SFs) play a major role in the pathogenesis of rheumatoid arthritis (RA) and develop an aggressive phenotype destroying cartilage and bone, thus termed RASFs.Objectives:We aim to examine the presence of GSDMD-mediated pyroptosis and its role in activated RASFs.Methods:Fibroblasts were isolated from RA synovium obtained from knee replacement surgeries. NLRP1, Caspase-1, GSDMD expression in synovial tissue and TNF-treated RASFs were assessed by qPCR and Western
more » ... PCR and Western blot. Interleukin (IL)-1 was measured by ELISA in supernatant after pretreated with TNF and barictinib. LDH release was measured using the CytoTox 96 Non-Radioactive Cytotoxicity Assay Kit. Endogenous NLRP1, Caspase-1, and GSDMD was knocked down using small interfering RNA.Results:The expressions of NLRP1, pro-Caspase-1, Caspase-1 p10, GSDMD and its pyroptosis-inducing fragment GSDMD-N were greater in RA synovium than OA synovium. TNF-induced NLRP1, pro-Caspase-1, Caspase-1 p10, GSDMD, and GSDMD-N expression at the transcript and protein level in a time-dependent manner (P < 0.05). Meanwhile, the release of LDH and IL-1 were significantly increased in RASFs after treated with TNF. We also confirmed the presence of pyroptosis in electron microscopy. Furthermore, blocking the JAK pathway with barictinib significantly reduced TNF-induced pyroptosis at the transcriptional, protein and activity levels (P < 0.05). Finally, blocking the JAK pathway, we observed a reduction of IL-1 bioactivity in RASFs (P < 0.05).Conclusion:Our results demonstrate an important role of GSDMD-mediated pyroptosis and shed lights on a potential pyroptosis-targeted treatment. Meanwhile, JAK inhibition alleviates inflammasome-induced pyroptosis by blocking pyroptosis pathway in RASFs.References:[1] Masters, S. L. et al. NLRP1 inflammasome activation induces pyroptosis of hematopoietic progenitor cells. Immunity,2012,37:1009–1023.Disclosure of Interests:None declared
doi:10.1136/annrheumdis-2020-eular.5062 fatcat:fw2e24xq7bbypao2vix5aooxwm