OP32 Pyroptosis Inhibition Prevents the Cytotoxicity Induced by IL-17 Without Impairing Its Beneficial Effects

Abstract

Abstract Background Th17 cells and their main secreting cytokine interleukin-17A (IL-17) are considered as the main pathogenic factors in inflammatory bowel diseases (IBDs). However, anti-IL-17 neutralizing antibodies, a theoretically curative medication for IBDs, paradoxically aggravated intestinal inflammation. The mechanisms by which it mediates the protective and pathologic effects of IL-17 remain unclear in the intestinal epithelium. Methods The intestinal epithelial responses induced by IL-17 was evaluated using the human small intestinal organoid (enteroid) model. Results Organoid-forming efficiency, cell viability and proliferation of enteroids were decreased in proportion to the concentration of IL-17, which did not differ between the enteroids derived from controls and patients with Crohn’s disease. Bulk RNA-sequencing revealed the enrichment of secretion signaling in IL17-treated enteroids. Among its components, PIGR was up-regulated significantly as the concentration of IL-17 increased, resulting in IgA transcytosis and protective role against pathogens. The IL-17-induced cytotoxicity was predominantly mediated by pyroptosis with activation of CASP1 and cleavage of GSDMD. Single-cell RNA- sequencing identified pyroptosis occurred actively in intestinal stem cells (ISCs) and enterocytes. Anti-IL-17 antibody, izekizumab, completely restored IL-17-induced cytotoxicity, but suppressed mucin secretion and IgA transcytosis. CASP1 inhibitor, Ac-YVAD-cmk, restores cytotoxicity induced by IL-17, without impairing its beneficial effects. Conclusion IL-17 induces pyroptosis of ISCs and enterocytes, as well as mucin secretion and PIGR-induced IgA transcytosis. Paradoxical gastrointestinal effects of IL-17 neutralizing antibodies may be associated with inhibition of mucin secretion and IgA transcytosis. The inhibition of pyroptosis using the CASP1 inhibitor prevents the cytotoxicity induced by IL-17 without compromising its beneficial effects.