Effect of abdominal paracentesis drainage on TLR4 expression in intestine of rats with severe acute pancreatitis and its significance

Objective　To investigate the potential mechanism of abdominal paracentesis drainage (APD) on severe acute pancreatitis (SAP) through regulating Toll-like receptor 4 (TLR4) expression in rat intestine. Methods　Male SD rats were randomized into the Sham group, SAP group, and APD group, with 15 rats in each group. Rats were treated with a retrograde injection of 5% sodium taurocholate into the pancreatic bile duct to induce SAP, followed by ADP treatment through placing a drainage tube in the right lower abdomen of rats. Rats without ADP treatment were used as controls: SAP group included rats without ADP surgical procedure; while Sham group included rats with ADP surgical procedure but without placing a drainage tube. About 24 hours after ADP treatment, pathological changes of small intestine and pancreas were observed by HE staining; serum amylase and lipase activities were detected by the automatic biochemical analyzer; serum endotoxin levels were detected by limulus amebocyte lysate method; serum DAO activity was detected by ultraviolet colorimetry; TNF-α, IL-6 and D-lactic acid levels were detected by ELISA; apoptosis of intestinal mucosal epithelial cells was detected by TUNEL assay; mRNA expression of TLR4 was detected by real-time PCR; the expression of TLR4 signaling pathway and apoptosis-related proteins were detected by immunohistochemistry and Western blotting. Results　Compared with SAP rats, the pathological damage of small intestine and pancreas of APD rats was significantly reduced; the pathological score was decreased (P<0.05); serum amylase, lipase and DAO activity, serum TNF-α, IL-6, D-lactic acid and endotoxin levels were also declined (P<0.05). The expression of TLR4, MyD88, NF-κB p65, TNF-α and IL-6 in the small intestine was significantly lower in the APD group than those in the SAP group (P<0.05). In addition, compared with the SAP group, apoptotic index, cleaved caspase-3, and Bax expression were significantly decreased in the APD group, while Bcl-2 expression was increased (P<0.05). Conclusion　Early implementation of APD can significantly reduce the expression of intestinal TLR4 in SAP rats, reduce the activation of a downstream inflammatory signaling pathway, and thus decrease the occurrence of intestinal mucosal epithelial cell apoptosis that contributes to intestinal protection. DOI: 10.11855/j.issn.0577-7402.2020.12.01