Activated protein C (APC) is known to have the cytoprotective effect on liver ischemia–reperfusion injury (IRI) in rat models. However, it is unclear that whether APC treatment is beneficial against steatotic liver IRI. We compared the cytoprotective effects of APC administration between steatotic and non-steatotic IRI liver in a mice model.

Methods: The mice were fed either a normal diet (ND mice) or a high fat diet (HF mice). Using 60-min partial warm ischemia model, both ND and HF mice were treated with APC or saline (control) before operation, at 8 and 16 h after reperfusion, and then sacrificed at 4 or 24 h after reperfusion. In vitro study, primary steatotic hepatocytes were treated with APC or not, and then incubated with H2O2.

Results: In ND mice, APC significantly reduced serum AST levels (1,879±344 vs. 4,741±2,167 IU/L, P<0.05), and decreased the number of Ly6G and MAC-1 positive cells (20.9±4.6 vs. 35.7±1.9, 22.3±4.9 vs. 32.5±1.9, P<0.05, respectively) as compared to control at 4 h. While, in HF mice, APC significantly reduced serum AST levels (4,032±1,160 vs. 6,218±954 IU/L, P<0.05), and decreased the number of Ly6G and MAC-1 positive cells (111.4±11.0 vs. 172.8±42.6, 132.4±37.7 vs. 206.8±40.4, P<0.05, respectively) at 24 h. APC was significantly reduced liver necrosis area in both mice (22.9±13.8 vs. 56.7±28.5%, 66.7±10.5 vs. 84.2±6.8%, P<0.05, respectively) at 24 h. APC protected sinusoidal endothelial cells damage evidenced by PECAM-1 expression in ND mice at 4 and 24 h (0.77±0.06 vs. 0.51±0.28, 1.45±0.50 vs. 0.96±0.18, P<0.05, respectively), but not in HF mice. In contrast, APC activated AMPK phosphorylation, which was associated with ATP consumption, in HF mice (1.21±0.21 vs. 0.83±0.13, P<0.05), but not in ND mice, at 4 h. In vitro study, hepatocytes with APC were markedly increased survival rates as compared to control (69.8±5.0 vs. 52.3±4.3 %, P<0.05). Additionally, APC significantly increased AMPK phosphorylation and ATP concentration in hepatocytes (2.08±0.75 vs. 1.07±0.26, P<0.01, 0.0066±0.0020 vs. 0.0045±0.0013 pmol/ng protein, P<0.05).

Conclusion: APC treatment for non-steatotic IRI mainly exerts cytoprotective effects via prevention of endothelial injury, while its treatment for steatotic IRI mainly provides cytoprotective effects via direct protection of hepatocytes through modulation of AMPK.

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