FRI0160 Interleukin-17a induces inflammatory response via nlrp3 inflammasome in ankylosing spondylitis

Background Inflammasomes are cytoplasmic multiprotein complexes that recognise various exogenous and endogenous danger signals in myeloid cells, particularly macrophages. Inflammasome activation eventually induces inflammatory responses in macrophages by activating gasdermin-d-mediated pyroptosis and the secretion of pro-inflammatory cytokines including interleukin (IL)−1β and IL-18 in a caspase-1-dependent manner. The production of IL-1 has been found to be highly induced in AS 1 and caspase-1 level was significantly elevated in spondyloarthritis patients than in those with other arthritic diseases, 2 suggesting the possibility that inflammasomes might be involved in pathogenesis of ankylosing spondylitis (AS). However, few studies have addressedd the roles of inflammasomes in AS. Objectives This study was performed to investigate the role of NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome in the peripheral blood mononuclear cells (PBMCs) from AS patients. Methods PBMCs from 11 patients and 9 healthy controls were isolated and mRNA expression levels of NLRP3 inflammasome, pro-IL-1β, IL-1β, pro-caspase-1, and caspase-1 were determined using quantitative real-time PCR. IL-17A (100 ng/mL) was added to the cell cultures, then, cytokine expression, signalling pathways, and inflammasome machinery are determined using real-time RT-PCR and Western blot. After transfection of siNLRP3 to AS PBMCs, mRNA and proteins levels of IL-1β and caspase-1 were determined using real time PCR and western blot. Results Expressions of NLRP3, IL-1β, and caspase-1 mRNAs, but not IL-18, were increased in PBMCs from AS patients compared to controls. Incubation of AS PBMCs with IL-17A significantly increased NLRP3, IL-1β, IL-18, and caspase-1 expressions in AS PBMCs. Western blot showed IL-17A treatment induced the phosphorylation of Akt, p38 MAPK, and NF-κB p65 in AS PBMCs. Down-regulation of NLRP3 by transfection of siRNA decreased mRNA expressions and productions of IL-1β and caspase-1 in AS PBMCs. Conclusions Activity of NLRP3 inflammasome was increased in AS patients and IL-17A potentiated the activation of NLRP3 inflammasome. Our data suggest the possible role of NLRP3 inflammasome in inflammatory response in AS. References [1] Tan AL, Marzo-Ortega H, O’Connor P, Fraser A, Emery P, McGonagle D. Efficacy of anakinra in active ankylosing spondylitis: a clinical and magnetic resonance imaging study. Ann Rheum Dis. 2004;63:1041–1045. [2] Son CN, Bang SY, Kim JH, Choi CB, Kim TH, Jun JB. Caspase-1 level in synovial fluid is high in patients with spondyloarthropathy but not in patients with gout. J Korean Med Sci. 2013;28:1289–1292. Disclosure of Interest None declared