GSDMD palmitoylation induces acinar cell pyroptosis via promoting GSDMD-N oligomerization to aggravate hyperlipidemic acute pancreatitis.

Abstract

Pancreatic acinar cell pyroptosis played a key role in acute pancreatitis (AP), while the underlying molecular mechanisms were unclear. In this study, hyperlipidemic acute pancreatitis (HLAP) model mice and primary acinar cells were employed for the in vivo and in vitro experiments, respectively. Western blot was employed to assess Gasdermin D-N-terminal pore-forming domain (GSDMD-N) oligomerization; Flow cytometry was employed to assess cell pyroptosis; Immunofluorescence was performed to assess GSDMD-N location in the cytoplasm; HE and TUNEL staining were employed to assess the pathological changes and cell apoptosis of pancreatic tissues. Palmitic acid levels were elevated in serum and pancreatic tissues of HLAP mice, palmitoyltransferase Zinc Finger DHHC Domain-Containing Protein 13 (ZDHHC13) and ZDHHC15 expression levels were markedly increased in primary acinar cells of HLAP mice. Acinar cells of HLAP mice exhibited the increased pyroptosis, which was evidenced by the increased cleaved-caspase-1 and GSDMD-N protein levels, Interleukin (IL)-1β, IL-18, and lactate dehydrogenase (LDH) release, GSDMD-N oligomerization, and caspase-1⁺PI⁺ cells. Mechanistically, palmitic acid induced GSDMD palmitoylation. ZDHHC15 interacted with GSDMD, and ZDHHC15 knockdown reduced GSDMD-N oligomerization and thereby suppressed pyroptosis in palmitic acid-treated acinar cells. The in vivo experiments further revealed that AAV-sh-ZDHHC15 reduced cell apoptosis and GSDMD-N oligomerization in pancreatic tissues of HLAP mice. In conclusion, this study identified a potential regulatory pathway of HLAP involving ZDHHC15-dependent modulation of GSDMD palmitoylation and subsequent GSDMD-N oligomerization.