To investigate the effect of ulinastatin on Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3)-mediated pyroptosis alleviates intestinal mucosal barrier injury in rats with severe acute pancreatitis (SAP).

Using the random number table method, 72 SD rats were randomly divided into sham operation group, SAP model group, low-dose ulinastatin group (5 000 U/kg), medium-dose ulinastatin group (10 000 U/kg), high-dose ulinastatin group (30 000 U/kg) and high-dose ulinastatin+BE (Broussonin E, JAK2 activator) group (30 000 U/kg+Broussonin E), 12 animals in each group. Except for the sham operation group, the other four groups were injected with 5% sodium taurocholate through the pancreatic duct to establish the SAP rat model. At 0, 6 and 12 h after modeling, the rats in low-dose ulinastatin group, middle-dose ulinastatin group, high-dose ulinastatin group, and high-dose ulinastatin+BE group were intraperitoneally injected with corresponding doses of drugs, and the rats in sham operation group and SAP model group were intraperitoneally injected with the same volume of PBS. After 24 hours of modeling, the ascites volume and the dry/wet mass ratio of pancreatic and intestinal tissues were measured; HE staining was used to observe the pathological changes of pancreatic and intestinal mucosa tissues; ELISA was used to detect serum tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-18, diamine oxidase (DAO) and intestinal fatty acid binding protein (IFABP) levels; immunohistochemical method and WB were used to detect the positive cells and protein expression of JAK2, STAT3, cleaved-caspase-1, and Gasdermin D-N (GSDMD-N). The experimenter was blinded during pathological scoring (Schmidt score, Chiu's score) and data measurement.

Compared with the sham operation group, the SAP model group had the lower pancreas and intestinal dry/wet mass ratio, pathological scores (Schmidt score, Chiu’s score), serum indicators (TNF-α, IL-1β, IL-18, DAO, IFABP) and JAK2, STAT3, cleaved-caspase-1, GSDMD-N positive cell expression and protein levels were significantly increased (all P<0.05). Compared with the SAP model group, the ascites volume, pathological scores, serum indicators, and positive cell expression and protein levels of JAK2, STAT3, cleaved-caspase-1 and GSDMD-N in rats treated with ulinastatin significantly reduced, and the dry/wet mass ratio of pancreas and intestine was increased in a dose-dependent manner (all P<0.05). Compared with the high-dose ulinastatin group, the ascites volume, pathological score, serum indexes, the positive cell expression and protein levels of JAK2, STAT3, cleaved-caspase-1 and GSDMD-N in the high-dose ulinastatin+BE group were significantly increased, and the dry/wet mass ratio of pancreas and intestine was decreased (all P<0.05).

Ulinastatin dose-dependently inhibits JAK2/STAT3 mediated intestinal cell pyroptosis, improves the inflammatory response of intestinal mucosa in SAP rats, and reduces mucosal barrier damage, with the optimal dose of 30 000 U/kg.