Mannan-binding lectin deficiency exacerbates sterile liver injury in mice through enhancing hepatic neutrophil recruitment

Noninfectious liver injury, including the effects of drugs and diet, is a major cause of liver diseases worldwide. The innate inflammatory response to hepatocyte death plays a crucial role in the outcome of liver injury. Mannan-binding lectin (MBL) is a pattern recognition molecule of the innate immune system, which is primarily produced by liver. MBL deficiency occurs with high frequency in the population and is reported associated with predisposition to infectious diseases. We here observed that genetic MBL ablation strongly sensitizes mice to sterile liver injury induced by carbon tetrachloride (CCl₄ ). Aggravated liver damage was shown in CCl₄ -administrated MBL^-/- mice, as evidenced by severe hepatocyte death, elevated serum alanine aminotransferase and lactate dehydrogenase activity, and enhanced production of inflammatory cytokines. Mechanistic studies established that MBL deficiency caused increased chemokine CXCL2 production from liver macrophages upon CCl₄ stimulation, thereby promoting the hepatic recruitment of neutrophils and subsequent liver damage. Furthermore, MBL-mediated protection from CCl₄ -induced liver injury was validated by administration of an MBL-expressing liver-specific adeno-associated virus, which effectively ameliorated the hepatic damage in CCl4-treated MBL^-/- mice. We propose that MBL may be exploited as a new therapeutic approach in the treatment of chemical-induced sterile liver injury in patients with MBL deficiency.