Mechanism of Huanglian Jiedutang in Inhibiting Activation of NLRP3 Inflammasomes and Ameliorating Acute Liver Injury in Septic Mice

Abstract:

Objective To explore the mechanism of Huanglian Jiedutang in inhibiting the pyroptosis mediated by NOD-like receptor protein 3 （NLRP3） inflammasomes and alleviating the acute liver injury （ALI） induced by lipopolysaccharide （LPS） in the mouse model of sepsis.Method Fifty-four male C57BL/6 mice were randomized into blank， model， low- （3.08 g·kg^-1）， medium- （6.15 g·kg^-1）， and high-dose （12.30 g·kg^-1） Huanglian Jiedutang， and positive control （dexamethasone） groups （n=9）. The mice were administrated with Huanglian Jiedutang at different doses by gavage for 7 days， and then LPS （15 mg·kg^-1） was injected intraperitoneally for the modeling of sepsis. In the positive control group， dexamethasone （0.05 g·kg^-1） was injected intraperitoneally 1.5 h after modeling， and the mouse sepsis score （MSS） was recorded 12 h after modeling. The mice were sacrificed for the collection of blood and liver tissue samples. The levels of alanine transaminase （ALT） and aspartate transaminase （AST） were measured by a biochemical analyzer. The levels of tumor necrosis factor （TNF）-α， interleukin （IL）-6， IL-1β， and IL-18 in the serum were measured by enzyme-linked immunosorbent assay kits. Hematoxylin-eosin staining was used to observe the pathological changes in the liver tissue. The content of NLRP3 was observed by the immunofluorescence assay. The expression of apoptosis-associated speck-like protein containing CARD （ASC） was detected by immunohistochemistry. The protein levels of NLRP3， ASC， Caspase-1， and gasdermin D （GSDMD） in the liver tissue were determined by Western blot. Real-time quantitative polymerase chain reaction（Real-time PCR） was employed to determine the mRNA levels of GSDMD， Caspase-1， IL-1β， and IL-18.Result Compared with the blank group， the model group showed elevated levels of ALT and AST （P<0.01） and risen levels of inflammatory cytokines in the serum （P<0.01）. In addition， the modeling resulted in edema and necrosis in the liver， and up-regulated the protein levels of GSDMD， NLRP3， ASC， and Caspase-1 （P<0.01） and the mRNA levels of GSDMD， Caspase-1， IL-1β， and IL-18 （P<0.01）. Compared with the model group， the drug intervention groups showed reduced content of inflammatory cytokines （P<0.01）， alleviated pathological damage in the liver tissue， and down-regulated protein levels of GSDMD， NLRP3， ASC， and Caspase-1 （P<0.05，P<0.01） and mRNA levels of GSDMD， Caspase-1， IL-1β， and IL-18 （P<0.05，P<0.01） in the liver tissue.Conclusion Huanglian Jiedutang can inhibit pyroptosis and reduce inflammation by inhibiting the activation of NLRP3 inflammasomes， thus demonstrating a therapeutic effect on acute liver injury in the mouse model of sepsis induced by LPS.