Published online Nov 28, 2019. doi: 10.3748/wjg.v25.i44.6527
Peer-review started: September 18, 2019
First decision: October 14, 2019
Revised: October 31, 2019
Accepted: November 13, 2019
Article in press: November 13, 2019
Published online: November 28, 2019
Massive hepatocyte death is the core event in acute liver failure (ALF). Gasdermin D (GSDMD)-mediated pyroptosis is a type of highly inflammatory cell death. However, the role of hepatocyte pyroptosis and its mechanisms of expanding inflammatory responses in ALF are unclear.
To investigate the role and mechanisms of GSDMD-mediated hepatocyte pyroptosis through in vitro and in vivo experiments.
The expression of pyroptosis pathway-associated proteins in liver tissues from ALF patients and a hepatocyte injury model was examined by Western blot. GSDMD short hairpin RNA (shRNA) was used to investigate the effects of downregulation of GSDMD on monocyte chemotactic protein 1 (MCP1) and its receptor CC chemokine receptor-2 (CCR2) in vitro. For in vivo experiments, we used GSDMD knockout mice to investigate the role and mechanism of GSDMD in a D-galactose/lipopolysaccharide (D-Galn/LPS)-induced ALF mouse model.
The levels of pyroptosis pathway-associated proteins in liver tissue from ALF patients and a hepatocyte injury model increased significantly. The level of GSDMD-N protein increased most obviously (P < 0.001). In vitro, downregulation of GSDMD by shRNA decreased the cell inhibition rate and the levels of MCP1/CCR2 proteins (P < 0.01). In vivo, GSDMD knockout dramatically eliminated inflammatory damage in the liver and improved the survival of D-Galn/LPS-induced ALF mice (P < 0.001). Unlike the mechanism of immune cell pyroptosis that involves releasing interleukin (IL)-1β and IL-18, GSDMD-mediated hepatocyte pyroptosis recruited macrophages via MCP1/CCR2 to aggravate hepatocyte death. However, this pathological process was inhibited after knocking down GSDMD.
GSDMD-mediated hepatocyte pyroptosis plays an important role in the pathogenesis of ALF, recruiting macrophages to release inflammatory mediators by upregulating MCP1/CCR2 and leading to expansion of the inflammatory responses. GSDMD knockout can reduce hepatocyte death and inflammatory responses, thus alleviating ALF.
Core tip: The expression of gasdermin D N terminal domain was significantly increased in the liver during human acute liver failure (ALF), in a D-galactose/lipopolysaccharide (D-Galn/LPS)-induced ALF mouse model and in D-Galn/LPS-treated AML12 hepatocytes. GSDMD-mediated hepatocyte pyroptosis expanded the inflammatory response by upregulating monocyte chemotactic protein 1 and its receptor CC chemokine receptor-2 to recruit macrophages. GSDMD knockout could significantly alleviate ALF in the mouse model. Finding effective intervention targets or drugs inhibiting GSDMD may provide a possible treatment approach to improve the outcomes of ALF.