Lipoxin A4 exerts protective effects against experimental acute liver failure by inhibiting the NF-κB pathway

Abstract

Although rare, acute liver failure (ALF) is associated with high levels of mortality, warranting the development of novel therapies. Nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) play roles in ALF. Lipoxin A4 (LXA4) has been shown to alleviate inflammation in non-hepatic tissues. In the present study, we explored whether LXA4 exerted hepatoprotective effects in a rat model of ALF. A rat model of ALF was generated by intraperitoneal injections of D-galactosamine (300 mg/kg) and lipopolysaccharide (50 µg/kg). Animals were randomly assigned to: control group (no ALF); model group (ALF); and the groups treated with a low dose (0.5 µg/kg), medium dose (1 µg/kg), and high dose (2 µg/kg) of LXA4 (all with ALF); and pyrrolidine dithiocarbamate (PDTC)-treated group (ALF and 100 mg/kg PDTC, an inhibitor of NF-κB). Liver histology was measured using H&E staining, serum levels by ELISA, and liver mRNA expression was measured by RT-PCR for the detection of the pro‑inflammatory cytokines TNF-α and IL-6. Liver cell apoptosis (as measured using the TUNEL method and examining caspase-3 activity), and Kupffer cell NF-κB activity [using an electrophoretic mobility shift assay (EMSA)] were examined. Serum levels of transaminases, TNF-α and interleukin-6 (IL-6) were substantially higher in the model group compared to controls. In the model group, significant increases in TNF-α and IL-6 mRNA expression, TUNEL‑positive cells, and caspase-3 activity in the liver tissue were noted. LXA4 improved liver pathology and significantly decreased the indicators of inflammatory response and apoptosis in a dose-dependent manner. High-dose LXA4 provided better protection than PDTC. LXA4 administration significantly decreased NF-κB expression in hepatocytes and Kupffer cells. These results indicated that LXA4 inhibited NF-κB activation, reduced the secretion of pro-inflammatory cytokines, and inhibited apoptosis of liver cells, thereby exerting protective effects against ALF.