Inhibition of MMP9 ameliorates neutrophil extracellular traps-mediated necroptosis through regulation of impaired autophagy in severe acute pancreatitis.

The positive feedback of acinar cell death, immune infiltration and inflammation aggravated the severity of the severe acute pancreatitis (SAP). Neutrophil extracellular traps (NETs) were demonstrated to trigger trypsin activation and organ damage. Exploration of the underlying mechanism of the damage effect of NETs on pancreas and potential to block the process was needed. The aim of this study was to explore the genes involved in the effect of NETs on pancreas in SAP and potential mechanism of inhibition of matrix metallopeptidase 9 (MMP9) in alleviating pancreatitis. RNA sequencing analysis was performed using human blood and mouse pancreatic tissues, and the mice AP models were established. The result showed that differentially expressed genes between clinical SAP and healthy patients enriched significantly in NETs formation. MMP9 was considered the hub gene in NETs and its expression increased accompanied with the aggravated organ damage and extensive NETs formation. The administration of MMP9-IN-1 alleviated pancreatic damage and necroptosis after the presence of NETs in vivo. KEGG enrichment analyses of acinar cells showed that autophagy was a vital process in pancreatic inflammatory injury, and the inhibition of MMP9 alleviated impaired autophagy. The effect of NETs on pancreatic necroptosis was further demonstrated to be associated with the regulation of impaired autophagy by MMP9. MMP9-IN-1 regulated SIRT2/NRF2 signaling pathway and alleviated pancreatic impaired autophagy and necroptosis. In conclusion, NETs formation is a key and predictive biological behavior of clinical SAP patients. MMP9 might be involved in NETs-mediated pancreatic damage and necroptosis by regulation of impaired autophagy during SAP.