PPARγ is essential for TEC to alleviate ANIT-induced experimental intrahepatic cholestasis
To further confirm the physiological roles of PPARγ in TEC-mediated hepatic protection in vivo, Ad-shPPARγ was injected into C57BL/6J mice via the tail vein. Next, the mice were treated with ANIT and/or TEC as described in the experimental method. As expected, TEC did not exert hepatic protection in ANIT-induced CLD of PPARγ deficient mice, which was supported by the fact that there was no obvious difference in AST, ALT, AP and necrosis area after TEC treatment in PPARγ-deficient mice (Figure 7A and 7B). Quantification of the bile acid pool size showed that there was no significant influence on the content of bile acid in the liver, serum and feces of PPARγ-deficient mice after TEC treatment (Figure 7C). ANIT treatment alone markedly promoted macrophage recruitment compared with NC, as evidenced by a significant increase in F4/80 mRNA level in the liver (Figure 7D). The mRNA levels of proinflammatory factors (Figure 7E) and profibrogenesis factors (Figure 7F) also supported these findings. PPARγ deficiency aggravated inflammation in mouse liver, as shown by increased F4/80, proinflammatory factors and profibrogenesis factors compared with ANIT treatment alone, while TEC did not significantly decrease these genes in PPARγ deficient mice. Furthermore, the expression of FXR and LXR in mouse liver was analyzed, and the results showed that TEC did not enhance the expression of FXR, LXR and bile transporters in PPARγ-deficient mice (Figure 7G and 7H). Taken together, the lack of PPARγ expression abolished hepatic protection by TEC.