Experimental study on liver ischemia reperfusion injury promoted by NOD1 activated pyroptosis

Objective To investigate the effect of nucleotide-binding oligomerization domain-containing protein 1 (NOD1) on pyroptosis in hepatic ischemia-reperfusion injury. Methods An animal model of ischemia-reperfusion injury was established. Thirty healthy, male, and clean C57 BL mice were randomly divided into sham operation group (sham group) and ischemia-reperfusion group (IR, including 2 h, 6 h, 12 h, 24 h subgroups), 6 per group. Serum ALT and AST levels in each group were measured by blood biochemistry. HE staining and TUNEL were used to observe the pathological changes of liver and hepatocyte apoptosis. Immunohistochemistry was used to detect the expression and distribution of NOD1 in each group. Western blotting was used to detect NOD1, AIM2, pro-Caspase-1 and active-Caspase-1 expression. NOD1 siRNA and empty control siRNA were transfected into AML12 cells, then the hypoxia/reoxygenation model was established and cells were collected to detect the expression of NOD1, AIM2 and active-Caspase-1. Results The ALT and AST levels in IR group were significantly higher than those in sham group, and peaked at IR 12-h subgroup (P<0.05). HE staining showed that hepatic injury was the most severe at 12 h after reperfusion. TUNEL results showed that the number of apoptotic cells was the greated at 12 h after reperfusion. Western blotting showed that NOD1 protein expression was highest at 12 h after reperfusion. With the prolongation of reperfusion time, the expression of AIM2 and active-Caspase-1 gradually increased, and that of pro-Caspase-1 gradually decreased. The expression of NOD1, AIM2 and active-Caspase-1 decreased after transfection of NOD1 siRNA into AML12 cells. Conclusions NOD1 promotes liver ischemia-reperfusion injury, which may be related to NOD1 promoting liver injury by activating pyroptosis. Key words: Reperfusion injury; Liver; Pyroptosis