Diacerein protects liver against APAP-induced injury via targeting JNK and inhibiting JNK-mediated oxidative stress and apoptosis.

An overdose of acetaminophen (APAP) causes acute liver damage and lead to liver failure. Therefore, it is of great clinical significance to find drugs for the treatment of APAP-induced liver injury. Diacerein is clinically used drug for the treatment of osteoarthritis. Here, we evaluate the pharmacological effects and potential mechanisms of diacerein in APAP-induced liver injury. C57BL/6 mice were treated with diacerein by gavage, followed by intraperitoneal injection of APAP (400 mg/kg) to induce acute liver injury in mice. RNA-sequencing analysis and in vitro kinase assay were performed to explore the underlying mechanisms of diacerein. The experimental results showed that pretreatment with diacerein could inhibit APAP-induced elevation of serum AST and ALT levels, hepatic histopathological damage, oxidative stress, hepatocyte death, and mitochondrial damage in mice. The RNA-sequencing analysis and in vitro kinase assay indicated that indicating that JNK (c-Jun N-terminal kinase) is involved in that liver-protective effects of Diacerein. Diacerein could directly and selectively inhibit JNK kinase phosphorylation in cell-free system. We further confirmed that diacerein inhibits APAP-activated JNK pathway to reduce injury response in mouse livers and cultured AML12 cells. Deficiency of JNK in AML12 cells abolished the anti-injury effects of diacerein. Our experimental results suggest that diacerein protects APAP-induced liver injury by the inhibition of JNK kinase phosphorylation, rendering diacerein may serve as a potential therapeutic drug for the prevention of acute liver injury.

Wang M ，Sun J ，Yu T ，Wang M ，Jin L ，Liang S ，Luo W ，Wang Y ，Li G ，Liang G ... -  《-》

Hydrogen sulfide protects against acetaminophen-induced acute liver injury by inhibiting apoptosis via the JNK/MAPK signaling pathway.

Acetaminophen (APAP) is a widely used over-the-counter analgesic and antipyretic. It can cause hepatotoxicity. Recent studies demonstrated that hydrogen sulfide (H2 S) exhibits cell protection in several cell types. This study was designed to investigate whether H 2 S ameliorated APAP-induced acute liver injury and to elucidate its mechanisms. In this study, we analyzed the detailed biological and molecular processes of APAP-induced hepatotoxicity using a bioinformatics analysis, which showed that apoptosis and the c-Jun N-terminal kinase (JNK)/mitogen-activated protein kinase pathway were confirmed to play critical roles in these processes. We further investigated the protective effects of H 2 S on APAP-induced hepatotoxicity. In vivo, we observed that the exogenous supplement of H 2 S ameliorated APAP-induced liver injury. Cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE) systems were the endogenous pathway of H 2 S. The expression of CBS/CSE was decreased in APAP-treated mice, while H 2 S could significantly restore it. In addition, APAP-induced JNK activation was inhibited by H 2 S in vivo. In vitro, H 2 S abolished the active effects of APAP on caspase3, Bax, and Bcl-2 expressions as well as JNK phosphorylation in hepatocytes. It was found through flow cytometry that the amount of APAP-induced apoptotic hepatocytes was decreased in the presence of H 2 S. In conclusion, our results suggested that H 2 S attenuated APAP-induced apoptosis in hepatocytes through JNK/MAPK siganaling pathway.

Li X ，Lin J ，Lin Y ，Huang Z ，Pan Y ，Cui P ，Yu C ，Cai C ，Xia J ... -  《-》

Deletion of apoptosis signal-regulating kinase 1 attenuates acetaminophen-induced liver injury by inhibiting c-Jun N-terminal kinase activation.

Nakagawa H ，Maeda S ，Hikiba Y ，Ohmae T ，Shibata W ，Yanai A ，Sakamoto K ，Ogura K ，Noguchi T ，Karin M ，Ichijo H ，Omata M ... -  《-》

Mangiferin ameliorates acetaminophen-induced hepatotoxicity through APAP-Cys and JNK modulation.

An overdose of the most popular analgesic, acetaminophen (APAP), is one of the leading causes of acute liver failure. It is well established that glutathione is exhausted by APAP-reactive intermediate N‑acetyl‑p‑benzoquinone-imine (NAPQI). This leads to elevated phosphorylated-c-Jun N-terminal kinase (p-JNK), which further activates reactive oxygen species (ROS), initiates an inflammatory response, and finally leads to severe hepatic injury. The present study was conducted to investigate the protective role of mangiferin (MAN), a naturally occurring xanthone and anti-oxidant, on APAP-induced hepatotoxicity. C57BL/6 mice were pretreated with or without MAN at 1 h prior to APAP challenge. MAN was administered at a dose of 12.5-50 mg/kg along with APAP at a dose of 400 mg/kg. According to the ALT/AST ratio, 25 mg/kg MAN was the most potent dose for further experiments. Serum ALT and AST depletion were observed in APAP + MAN (25 mg/kg)-treated mice at 6, 12, and 24 h. Early (1 h after APAP treatment) GSH depletion by APAP overdose was restored by MAN treatment, which reduced APAP-Cys adduct formation and promoted protection. p-JNK downregulation and AMPK activation were observed in MAN-treated mice, which could mechanistically reduce oxidative stress and inflammation. MAN up-regulated liver GSH and SOD and reduced lipid peroxidation. HO-1 protein and p47 phox mRNA expression indicated that MAN regulated oxidative stress along with JNK deactivation. The expression of inflammatory response genes TNF-α, IL-6, MCP-1, CXCL-1, and CXCL-2 reached the basal levels after MAN treatment. mRNA, protein, and serum levels of IL-1β were reduced, and NF-κB expression was similar to that of the MAN-treated APAP mice. MAN post-treatment (1 h after APAP treatment) also protected the mice from hepatotoxicity. In conclusion, MAN had a protective and therapeutic role in APAP-induced hepatotoxicity by improving the metabolism of acetaminophen and APAP-Cys adduct formation followed by JNK-mediated oxidative stress and inflammation.

Chowdhury A ，Lu J ，Zhang R ，Nabila J ，Gao H ，Wan Z ，Adelusi Temitope I ，Yin X ，Sun Y ... -  《-》

Editor's Highlight: Metformin Protects Against Acetaminophen Hepatotoxicity by Attenuation of Mitochondrial Oxidant Stress and Dysfunction.

Overdose of acetaminophen (APAP) causes severe liver injury and even acute liver failure in both mice and human. A recent study by Kim et al. (2015, Metformin ameliorates acetaminophen hepatotoxicity via Gadd45β-dependent regulation of JNK signaling in mice. J. Hepatol. 63, 75-82) showed that metformin, a first-line drug to treat type 2 diabetes mellitus, protected against APAP hepatotoxicity in mice. However, its exact protective mechanism has not been well clarified. To investigate this, C57BL/6J mice were treated with 400 mg/kg APAP and 350 mg/kg metformin was given 0.5 h pre- or 2 h post-APAP. Our data showed that pretreatment with metformin protected against APAP hepatotoxicity, as indicated by the over 80% reduction in plasma alanine aminotransferase (ALT) activities and significant decrease in centrilobular necrosis. Metabolic activation of APAP, as indicated by glutathione depletion and APAP-protein adducts formation, was also slightly inhibited. However, 2 h post-treatment with metformin still reduced liver injury by 50%, without inhibition of adduct formation. Interestingly, neither pre- nor post-treatment of metformin inhibited c-jun N-terminal kinase (JNK) activation or its mitochondrial translocation. In contrast, APAP-induced mitochondrial oxidant stress and dysfunction were greatly attenuated in these mice. In addition, mice with 2 h post-treatment with metformin also showed significant inhibition of complex I activity, which may contribute to the decreased mitochondrial oxidant stress. Furthermore, the protection was reproduced in JNK activation-absent HepaRG cells treated with 20 mM APAP followed by 0.5 or 1 mM metformin 6 h later, confirming JNK-independent protection mechanisms. Thus, metformin protects against APAP hepatotoxicity by attenuating the mitochondrial oxidant stress and subsequent mitochondrial dysfunction, and may be a potential therapeutic option for APAP overdose patients.

Du K ，Ramachandran A ，Weemhoff JL ，Chavan H ，Xie Y ，Krishnamurthy P ，Jaeschke H ... -  《-》