Effect of biliary drainage on inducible nitric oxide synthase, CD14 and TGR5 expression in obstructive jaundice rats

Abstract

To investigate the effect of biliary drainage on inducible nitric oxide synthase (iNOS), CD14 and TGR5 expression in rats with obstructive jaundice (OJ). Male adult Sprague-Dawley rats were randomly assigned to four groups: OJ, sham operation (SH), internal biliary drainage (ID) and external biliary drainage (ED). Rat models were successfully established by two operations and succumbed for extraction of Kupffer cells (KCs) and liver tissue collection on the 8(th) and 15(th) day. KCs were isolated by in situ hepatic perfusion and digested with collagen IV, density gradient centrifuged by percoll reagent and purified by cell culture attachment. The isolated KCs were cultured with the endotoxin lipopolysaccharide (LPS) with and without the addition of ursodeoxycholic acid (UDCA). The expression of iNOS, CD14 and bile acid receptor-TGR5 protein in rat liver tissues was determined by immunohistochemistry. The expression of iNOS and CD14 messenger RNA (mRNA) on the isolated KCs was detected by reverse transcription polymerase chain reaction (PCR) and the TGR5 mRNA level in KCs was measured by real-time quantitative PCR. The iNOS protein was markedly expressed in the liver of OJ rats, but rare expressed in SH rats. After relief of OJ, the iNOS expression was decidedly suppressed in the ID group (ID vs OJ, P < 0.01), but obviously increased in rats of ED (ED vs OJ, P = 0.004). When interfered only with LPS, the expression of iNOS mRNA by KCs was increased in the OJ group compared with the SH group (P = 0.004). After relief of biliary obstruction, the iNOS mRNA expression showed slight changes in the ED group (ED vs OJ, P = 0.71), but dropped in the ID group (ID vs OJ, P = 0.001). Compared with the simple intervention with LPS, the expressions of iNOS mRNA were significantly inhibited in all four groups after interfered with both LPS and UDCA (P < 0.01, respectively). After bile duct ligation, the CD14 protein expression in rat liver was significantly strengthened (OJ vs SH, P < 0.01), but the CD14 mRNA level by KCs was not up-regulated (OJ vs SH, P = 0.822). After relieving the OJ, the expression of CD14 protein was reduced in the ID group (ID vs OJ, P < 0.01), but not reduced in ED group (ED vs OJ, P = 0.591). And then the CD14 mRNA expression was aggravated by ED (ED vs OJ, P < 0.01), but was not significantly different between the ID group and the SH and OJ groups (ID vs SH, P = 0.944; ID vs OJ, P = 0.513, respectively). The expression of TGR5 protein and mRNA increased significantly in OJ rats (OJ vs SH, P = 0.001, respectively). After relief of OJ, ID could reduce the expression of TGR5 protein and mRNA to the levels of SH group (ID vs SH, P = 0.22 and P = 0.354, respectively), but ED could not (ED vs SH, P = 0.001, respectively). ID could be attributed to the regulatory function of activation of KCs and release of inflammatory mediators.