NLRP3 is dispensable for D-galactosamine/Lipopolysaccharide-induced fulminant hepatitis

Abstract Background: The NOD-like receptor family protein 3 (NLRP3) inflammasome is involved in the progression of liver inflammation. NLRP3 inactivation has been shown to protect mice against multiple types of experimental liver injury. However, it is unclear whether NLRP3 contributes to D-Galactosamine (DGalN) plus lipopolysaccharide (LPS) induced fatal hepatitis. This study aims to examine the function of NLRP3 inflammasome in DGalN/LPS induced acute liver failure.Method: The expression of inflammasomes was detected by quantitative PCR. Wild type (WT) mice and NLRP3 knockout mice were given an intraperitoneal injection of DGalN plus LPS. Liver damage was examined at 6 h post DGalN/LPS administration by histological analysis and serum aminotransferases measurement. Hepatocyte apoptosis and pyroptosis was detected with TUNEL assay, immunohistochemistry (IHC) staining, and western blot. Hepatic macrophages (F4/80+) and neutrophils (Ly6G+) were analyzed by IHC staining. The proinflammatory cytokines levels in serum and liver were examined using cytometric bead array and quantitative PCR. Hepatic IL1β level was further detected by western blot.Result: The hepatic NLRP3 activity was upregulated in WT mice treated with DGalN/LPS. Nlrp3−/− and WT mice showed similar mortality against lethal dose of DGalN/LPS. Serum aminotransferases levels and liver necrosis area of Nlrp3−/− mice did not differ from that in WT mice after DGalN/LPS injection. The numbers of liver TUNEL positive cells and cleaved caspase3 positive hepatocytes were comparable between Nlrp3−/− and WT mice. The hepatic GSDMDNterm peptide production also showed no difference between Nlrp3−/− and WT mice. Mice treated with DGalN/LPS displayed significantly increased numbers of intrahepatic F4/80+ cells and Ly6G+ cells, but the cell numbers in Nlrp3−/− mice livers were similar to those in WT mice. Consistently, serum and hepatic TNFα, IL6, and MCP-1 levels were similar between Nlrp3−/− and WT mice upon DGalN/LPS administration, but serum IL1β and hepatic mature IL1β level in Nlrp3−/− mice was reduced.Conclusions: NLRP3 ablation does not protect mice from DGalN/LPS induced acute liver failure, nor affect hepatocyte apoptosis and pyroptosis. Deficiency of NLRP3 has a limited effect on intrahepatic inflammatory response induced by DGalN/LPS treatment. NLRP3 inflammasome does not appear to be a major contributor to DGalN/LPS induced fatal hepatitis.