Objective  To investigate the effect and its molecular mechanism of phosphoglycerate mutase 5 (PGAM5) mediated pyroptosis on liver ischemia-reperfusion injury (IRI).

  Methods  C57 mouse models of liver IRI were established and randomly divided into the 6 h reperfusion (6 h group) and 12 h reperfusion (12 h group), and sham operation group (sham group) was established too, 10 rats in each group. The effect of IRI on the parameters in the liver tissues and serum samples was evaluated. The expression levels of PGAM5 and cysteinyl aspartate specific proteinase (Caspase)-1 in the liver tissues during IRI were quantitatively detected. The IRI models of liver cells were established (IRI group). The IRI models of liver cells were established after pretreatment with Caspase-1 inhibitor Z-YVAD-FMK (inhibitor group). The untreated AML12 cells were allocated into the control group. The effect of inhibiting Caspase-1 activity on pyroptosis was analyzed. AML12 cells were transfected with PGAM5 small interfering ribonucleic acid (siRNA) (siRNA group) and siRNA-negative control (siRNA-NC) (siRNA-NC group) by liposome 3000, and then IRI models of liver cells were established. The untreated AML12 cells were assigned into the control group. The effect of PGAM5 mediated pyroptosis on IRI of liver cells was assessed.

  Results  In the 6 h and 12 h groups, partial liver cell edema, hepatic sinusoid narrowing, central vein congestion and occasional spot necrosis were observed in the mouse liver tissues, and these changes in the 12 h group were more aggravated than those in the 6 h group. The serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the 6 h and 12 h groups were higher than those in the sham group, and the values in the 12 h group were higher than those in the 6 h group. The levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β were increased in the 6 h and 12 h groups, and the values in the 12 h group were lower than those in the 6 h group. The relative expression levels of IL-1β messenger ribonucleic acid (mRNA) in the mouse liver tissues in the 6 h and 12 h groups were up-regulated, and the value in the 12 h group was lower than that in the 6 h group. The cell apoptosis rates in the liver tissues were significantly increased in the 6 h and 12 h groups, and the value in the 12 h group was remarkably lower than that in the 6 h group (P < 0.01-0.05). Compared with the sham group, the relative expression levels of PGAM5 mRNA and protein in the mouse liver tissues in the 6 h and 12 h groups were significantly up-regulated, and the values in the 12 h group were significantly higher than those in the 6 h group (P < 0.01-0.05). The protein expression levels of PGAM5 and Caspase-1 in the liver tissues were up-regulated in the 6 h and 12 h groups. Compared with the control group, the relative expression levels of NOD-like receptor protein 3 (NLRP3), cleaved Caspase-1 and Gasdermin D (GSDMD) proteins were up-regulated and the fluorescence intensity of GSDMD was increased in the IRI group. Compared with the IRI group, the relative expression levels of NLRP3, cleaved Caspase-1 and GSDMD proteins were significantly down-regulated and the fluorescence intensity of GSDMD was considerably decreased in the inhibitor group (P < 0.01-0.05). Compared with the control group, the cell survival rate was significantly decreased, and the relative expression levels of PGAM5, NLRP3, cleaved Caspase-1 and GSDMD proteins were significantly up-regulated in the siRNA-NC group (P < 0.01-0.05). Compared with the siRNA-NC group, the cell survival rate was remarkably increased, whereas the relative expression levels of PGAM5, NLRP3, cleaved Caspase-1 and GSDMD proteins were significantly down-regulated in the siRNA group (P < 0.01-0.05).

  Conclusions  PGAM5 may aggravate the liver IRI in mouse models probably by mediating pyroptosis via PGAM5/Caspase-1/GSDMD signaling pathway and aggravating liver cell injury.