PPAR γ Alleviates Sepsis-Induced Liver Injury by Inhibiting Hepatocyte Pyroptosis via Inhibition of the ROS/TXNIP/NLRP3 Signaling Pathway

Abstract

Sepsis is a systemic inflammatory response syndrome caused by a dysregulated host response to infection. Peroxisome proliferator-activated receptor gamma (PPARγ) exerts anti-inflammatory and antioxidative properties. To investigate the potential effects of PPARγ on sepsis-induced liver injury and determine the related mechanisms, C57BL/6 male mice were subjected to cecal ligation and puncture (CLP) to create a sepsis model which was treated with GW1929 or GW9662 to upregulate or downregulate the expression of PPARγ. We found that upregulation of PPARγ decreased the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (TBIL), and liver pathological damage and improved the 5-day survival rate. Increased expression of PPARγ also decreased sepsis-induced reactive oxygen species (ROS) by promoting the expression of Nrf2. In addition, upregulated PPARγ inhibited the expression of the TXNIP/NLRP3 signaling pathway by reducing ROS-induced injury in the liver during sepsis, which further reduced NLRP3-mediated pyroptosis and the inflammatory response. The role of PPARγ was further examined in in vitro experiments, where lipopolysaccharide- (LPS-) treated HepG2 and Hep3B cells were incubated with GW1929 or GW9662 to upregulate or downregulate the expression of PPARγ. We found that upregulated PPARγ ameliorated LDH release and improved cell viability. Our results indicated that increased expression of PPARγ reduced ROS levels and inhibited the TXNIP/NLRP3 signaling pathway, resulting in decreased pyroptosis and reduced liver dysfunction during sepsis.