Investigation About The Role Of RIPK1 Kinase In Acetaminophen-induced Acute Liver Injury And Related Therapeutic Application

Hepacellular death and hepatic inflammation have been well recognized as central characteristics of acute liver injury induced by Acetaminophen（APAP）overdose.However,the underlying molecular mechanisms remains elusive and there is no effective therapeutic options for the acute liver injury induced by APAP overdose.RIPK1（Receptor-interacting protein kinase 1）is one of the key proteins regulating apoptosis,necroptosis and inflammation,and RIPK1 kinase activity plays an important role in a variety of physiological and pathological processes.This study used RIPK1 kinase-dead mice(Rip1^K45A/K45A)to construct an APAP-induced acute liver injury model to explore the role of RIPK1 kinase activity in APAP-induced acute liver injury and the underlying mechanisms.Our results indicated that RIPK1 kinase inactivation could significantly alleviate APAP-induced acute liver injury by reducing APAP-induced inflammatory response,endoplasmic reticulum stress and RIPK1-dependent apoptosis,and could markedly rescue the lethality caused by high dose of APAP treatment.We also used bone marrow transplantation model to explore the role of RIPK1 kinase activity in bone marrow-derived macrophages in APAP-induced acute liver injury.The results demonstrated that in contrast to whole-body RIPK1kinase inactivation,the liver damage caused by APAP could not be alleviated in chimeric mice transplanted with Rip1^K45A/K45A mouse bone marrow cells,suggesting that RIPK1 kinase activity in liver resident cells may play a major role.Next we isolated mouse primary hepatocytes and bone marrow-derived macrophages,treated them with APAP in vitro,and pretreated them either with RIPK1 kinase inhibitors Nec-1 and Nec-1s or vehicle control.The results showed that RIPK1 kinase inhibitor could significantly block the cell death of mouse primary hepatocytes induced by APAP but had no effect on the cytotoxicity of bone marrow-derived macrophages.At the same time,we utilized RIPK1 kinase inhibitor to explore its therapeutic effect in APAP-induced liver injury mouse model,and found that Nec-1 can effectively alleviate APAP-induced acute liver injury in mice.In summary,our study revealed the important role of RIPK1 kinase activity in APAP-induced acute liver injury,and suggested that RIPK1 kinase activity could be used as a potential therapeutic target for the treatment of APAP-induced acute liver injury.