Activation of NLRP3 Inflammasomes in Non‐alcoholic Steatohepatitis: A Novel Molecular Target of FTZ Remedy for Metabolic Syndrome

Abstract

NLRP3 inflammasome activation not only serves as an intracellular machinery triggering inflammation, but also produces uncanonical effects beyond inflammation such as changing cell metabolism, inducing cell transformation and increasing cell membrane permeability. The present study was designed to test whether this NLRP3 inflammasome activation plays a crucial role in the ‘two‐hit’ injury during non‐alcohilic steatohepatitis (NASH) and whether this inflammasome can be a therapeutic target for the action of Fufang Zhenzhu Tiaozhi (FTZ), a widely used herbal remedy for metabolic syndrome in China. By confocal microscopy, oil red O staining and immunohistochemistry, we demonstrated that NLRP3 inflammasomes formation and activation as well as lipid deposition occurred in the liver of mice on the high fat diet (HFD), as shown by increased NLRP3 components colocalization, enhanced production of IL‐1b and HMGB1, and remarkable lipid deposition in liver cells. FTZ extracts were found to not only significantly reduce the NLRP3 inflammasome formation and activation (from 1.46&1.81 to 1.01&1.29 folds of control), but also attenuated the liver steatosis (from 41.13% to 17.96%). In in vitro studies, palmitic acid (PA) was used to induce NLRP3 inflammasome activation and lipid deposition in hepatic stellate cells (HSCs). It was found that PA increased colocalization of NLRP3 components and enhanced cellular caspase‐1 activity (to 2.28 folds of control), indicating the formation and activation of NLRP3 inflammasomes. PA also increased HMGB1 production and enhance the lipid deposition in these cells. In FTZ treated cells, not only inflammasome activation was attenuated (from 1.78&1.81 to 1.01&1.07 folds of control, respectively), but also lipid deposition in HSCs was blocked, which was similar to the effects of GLY, an HMGB1 inhibitor (from 18.87% to 0.46%&4.29%, respectively). Mechanistically, we found that PA stimulated O2.− production (to 2.71 folds of control) to activate NLRP3 inflammasomes in HSCs, which was blocked by FTZ treatment as did by NAC, a O2.− scavenger (to 0.86 and 1.33 folds of control, respectively). It is concluded that NLRP3 inflammasomes formation and activation may contribute to the development of both lipid deposition and inflammation during NASH and that FTZ inhibits NASH by its action on both inflammatory response and liver lipid metabolism associated with NRLP3 inflammasome activation.Support or Funding Informationsupported by NSFC grants (81530102 to J. G) and NIH grants (HL057244 and HL075316 to P.L.)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.