Protective Effect Of CLEC18A In Acetaminophen-induced Liver Injury And Its Potential Mechanism In Mice

BackgroundDrug-induced liver injury（DILI）is a common drug adverse reaction,which can involve to acute liver failure and even death.Intrinsic DILI mainly occurs after intentional or accidental overdose of a drug,among which acetaminophen（APAP）is the representative drug.APAP overdose is a major cause of DILI and acute liver failure（ALF）.While the antidote N-acetylcysteine（NAC）is quite effective in early presenting patients,most patients presented to emergency room can not receive NAC in time and will undergo severe liver injury.Liver transplantation is the only treatment at this stage,which is limited by the rare sources of liver and damages of anti-rejection medication after the operations.Therefore,exploring protective factors in APAP-induced liver injury can provide new strategies for its treatment.C-type lectin domain family 18A（CLEC18A）is a newly discovered class of secretory lectin in recent years.Studies have found that the elevation of CLEC18A in plasma has a certain predictive value for hepatitis B and C infection,but the role of CLEC18A in drug-induced liver injury has not been reported.The purpose of this study is to investigate the role of CLEC18A in APAP-induced liver injury and its potential mechanism.Methods1.8-to 12-week-old male C57BL/6 mice were fasted overnight for 16 hours and then treated with APAP intraperitoneally.Mice were killed at given times after receiving APAP and serum and liver samples were collected for analyses.CLEC18A expression in whole mouse liver were quantified by RT-PCR and ELISA.2.8-to 12-week-old male CLEC18A^fl/fl Lyz-cre⁺mice and their non-transgenic littermates(CLEC18A^fl/flLyz-cre^-mice)were fasted for 16 h before intraperitoneal injection with APAP.The animals were sacrificed 24 h after the injection.Blood and liver were harvested for analyses of ALT and AST.3.After fasting 16 h,8-to 12-week-old male CLEC18A^fl/fl Alb-cre⁺mice and CLEC18A^fl/fl Alb-cre^-mice were injected with APAP intraperitoneally and sacrificed 24hours after treatment.Serum and liver samples were collected to examine ALT,AST,hematoxylin-eosin staining analysis and TUNEL analysis.The expression of CCAAT/enhancer-binding protein homologous protein（CHOP）was measured by immunohistochemical staining.4.8-to 12-week-old male CLEC18A^fl/fl Alb-cre⁺mice and CLEC18A^fl/fl Alb-cre^-mice were fasted for 16 h before intraperitoneal injection with APAP.Mice were killed 4 h after receiving APAP and liver samples were collected for analyses.Cytochrome P450 2E1（CYP450 2E1）and ER stress related proteins expression were detected by western blot.Glutathione（GSH）concentration analysis used commercial kits according to the manufacturer’s instructions.5.After fasting 16 h,8-to 12-week-old male CLEC18A^fl/fl Alb-cre⁺mice and CLEC18A^fl/fl Alb-cre^-mice were divided into two groups:APAP and APAP+inhibitor.tauroursodeoxycholic acid（TUDCA）were administered by group APAP+inhibitor 30 min before APAP treatment on both groups.Blood and liver were harvested for ALT,AST analysis and hematoxylin-eosin staining.Results1.CLEC18A expression increased in C57BL/6 mice with APAP-induced liver injury.2.CLEC18A myeloid cell-specific knockout mice were not different from their wildtype littermates in ALT and AST after receiving APAP.3.Liver-specific deficiency of CLEC18A Mice were sensitized toward APAP-induced liver injury.4.There was no significant difference between liver-specific knockout of CLEC18A and their wildtype littermates in liver CYP450 2E1 and GSH expression after APAPadministration.5.Liver-specific deficiency of CLEC18A mice were sensitized toward apoptosis and necrosis in APAP-induced liver injury.6.Protein kinase R-like endoplasmic reticulum kinase（PERK）phosphorylation and CHOP expression were increased in liver-specific deficiency of CLEC18A mice.7.Endoplasmic reticulum inhibitor reversed the protective effect of CLEC18A on APAP-induced liver injury.ConclusionThe results reveal that a novel C-type lectin CLEC18A play a protective role in APAP-induced liver injury by inhibiting the endoplasmic reticulum stress and reducing hepatocyte necrosis and apoptosis.Understanding its regulatory mechanism may provide new strategies for treatment of drug-induced liver injury.