Project description:Acetaminophen-induced liver injury (AILI) occurs frequently and can be life threatening. Although AILI is mainly caused by the direct drug cytotoxicity, increasing evidence suggests that the interplay between hepatocytes and immune cells can define this pathogenic process. To further understand the immunoregulatory role of SRA in AILI, we performed RNA-sequencing analysis using hepatic nonparenchymal cells (NPCs) derived from acetaminophen treated WT or SRA-/- mice to demonstrate hepatocyte-extrinsic mechanisms governed by the immune receptor SRA that maintains liver homeostasis upon drug insult.
Project description:In this study, we explored the role of macrophage scavenger receptor 1 (MSR1) in the progression of non-alcoholic fatty liver disease. Mice lacking Msr1 proved to be protected against high fat-cholesterol diet (HFD)-induced metabolic disorder, showing fewer hepatic lipid-laden foamy macrophages, less hepatic inflammation and changed lipid metabolism.
Project description:Drug-induced liver injury (DILI), especially acetaminophen overdose, is the leading cause of acute liver failure. Pregnane X receptor (PXR) is a nuclear receptor and the master regulator of drug metabolism. Aberrant activation of PXR plays a pathogenic role in the acetaminophen hepatotoxicity. Here, we aimed to examine the PXR S-nitrosylation (SNO) in response to acetaminophen. We found that PXR was S-nitrosylated in hepatocytes and the mouse livers after exposure to acetaminophen or S-nitrosoglutathione (GSNO). Mass-spectrometry and site-directed mutagenesis identified the cysteine 307 as the primary residue for SNO-modification. In hepatocytes, SNO suppressed both agonist (rifampicin and SR12813)-induced and constitutively active PXR (VP-PXR) activations. Furthermore, in acetaminophen overdosed mouse livers, PXR protein was decreased at the centrilobular regions overlapping with increased SNO. In PXR-deficient (PXR-/-) mice, replenishing the livers with the SNO-deficient PXR significantly aggravated hepatic necrosis and apoptosis, increased HMGB1 release, and exacerbated liver injury and inflammation. Particularly, we demonstrated that S-nitrosoglutathione reductase (GSNOR) inhibitor N6022 promoted hepatoprotection by increasing the levels of PXR S-nitrosylation. In conclusion, PXR is post-translationally modified by S-nitrosylation in hepatocytes in response to acetaminophen. This modification mitigated the acetaminophen-induced PXR hyperactivity. It may serve as a new target for therapeutical intervention.
Project description:Abnormalities in hepatic lipid metabolism are believed to play a critical role in the etiology of nonalcoholic steatohepatitis (NASH). Monoacylglycerol acyltransferase (MGAT) enzymes convert monoacylglycerol to diacylglycerol, which is the penultimate step in one pathway for triacylglycerol (TAG) synthesis. Hepatic expression of Mogat1, which encodes an MGAT enzyme, is increased in the livers of mice with hepatic steatosis and knocking down Mogat1 improves insulin sensitivity, but whether increased MGAT activity plays a role in the etiology of NASH is unclear. To examine the effects of knocking down Mogat1 in the liver on the development of NASH, C57BL/6 mice were placed on a diet containing high levels of trans fatty acids, fructose, and cholesterol (HTF-C diet) or a low fat control diet for 4 weeks. Mice were then injected with antisense oligonucleotides (ASO) to knockdown Mogat1 or a scrambled ASO control for 12 weeks while remaining on diet. HTF-C diet caused glucose intolerance, hepatic steatosis, and induced hepatic gene expression markers of inflammation, macrophage infiltration, and stellate cell activation. Mogat1 ASO treatment, which suppressed Mogat1 expression in liver, attenuated weight gain, improved glucose tolerance, and decreased hepatic TAG content compared to control ASO-treated mice on HTF-C chow. However, Mogat1 ASO treatment did not reduce hepatic DAG, cholesterol, or free fatty acid content, improve histologic measures of liver injury, or reduce expression of markers of stellate cell activation, liver inflammation, and injury. In conclusion, inhibition of hepatic Mogat1 in HTF-C diet-fed mice improves glucose tolerance and hepatic TAG accumulation without attenuating liver inflammation and injury. Total RNA obtained from liver of 4 control vs. 4 Mogat1 ASO treated higf-fat diet (HFD) fed mice.
Project description:The well-known difference in sensitivity of mice and rats to acetaminophen (APAP) liver injury has been related to differences in the fraction that is bioactivated to the reactive metabolite N-acetyl-p-benzoquinoneimine (NAPQI). Physiologically-based pharmacokinetic modelling was used to identify doses of APAP (300 and 1000 mg/kg in mice and rats, respectively) yielding similar hepatic burdens of NAPQI, to enable the comparison of temporal liver tissue responses under conditions of equivalent chemical insult.
Project description:In this study we conducted transcriptomics analyses of: (i) liver samples from patients suffering from acetaminophen-induced acute liver failure (n=3) and from healthy livers (n=2) and (ii) hepatic cell systems exposed to acetaminophen, including their respective vehicle controls. The investigated in vitro systems are: HepaRG cells, HepG2 cells and a novel human skinpostnatal stem cell-derived model i.e. human skin-precursors-derived hepatocyte-like cells (hSKP-HPC). Clinical samples were obtained after surgical removal of the explant liver of patients diagnosed with ALF due to acetaminophen intoxication and treated by orthotopic liver transplantation (n=3). Samples from healthy livers were obtained from individuals deceased from brain damage (n=2).
Project description:Abnormalities in hepatic lipid metabolism are believed to play a critical role in the etiology of nonalcoholic steatohepatitis (NASH). Monoacylglycerol acyltransferase (MGAT) enzymes convert monoacylglycerol to diacylglycerol, which is the penultimate step in one pathway for triacylglycerol (TAG) synthesis. Hepatic expression of Mogat1, which encodes an MGAT enzyme, is increased in the livers of mice with hepatic steatosis and knocking down Mogat1 improves insulin sensitivity, but whether increased MGAT activity plays a role in the etiology of NASH is unclear. To examine the effects of knocking down Mogat1 in the liver on the development of NASH, C57BL/6 mice were placed on a diet containing high levels of trans fatty acids, fructose, and cholesterol (HTF-C diet) or a low fat control diet for 4 weeks. Mice were then injected with antisense oligonucleotides (ASO) to knockdown Mogat1 or a scrambled ASO control for 12 weeks while remaining on diet. HTF-C diet caused glucose intolerance, hepatic steatosis, and induced hepatic gene expression markers of inflammation, macrophage infiltration, and stellate cell activation. Mogat1 ASO treatment, which suppressed Mogat1 expression in liver, attenuated weight gain, improved glucose tolerance, and decreased hepatic TAG content compared to control ASO-treated mice on HTF-C chow. However, Mogat1 ASO treatment did not reduce hepatic DAG, cholesterol, or free fatty acid content, improve histologic measures of liver injury, or reduce expression of markers of stellate cell activation, liver inflammation, and injury. In conclusion, inhibition of hepatic Mogat1 in HTF-C diet-fed mice improves glucose tolerance and hepatic TAG accumulation without attenuating liver inflammation and injury.
Project description:In this study we conducted transcriptomics analyses of: (i) liver samples from patients suffering from acetaminophen-induced acute liver failure (n=3) and from healthy livers (n=2) and (ii) hepatic cell systems exposed to acetaminophen, including their respective vehicle controls. The investigated in vitro systems are: HepaRG cells, HepG2 cells and a novel human skinpostnatal stem cell-derived model i.e. human skin-precursors-derived hepatocyte-like cells (hSKP-HPC). Clinical samples were obtained after surgical removal of the explant liver of patients diagnosed with ALF due to acetaminophen intoxication and treated by orthotopic liver transplantation (n=3). Samples from healthy livers were obtained from individuals deceased from brain damage (n=2). Different samples of hSKP, HepG2 and HepaRG were obtained from the same cell batch of each cell system. All cells were exposed for 24 hours to their corresponding sub cytotoxic concentrations (IC10): IC10(hSKP-HPC)=18mM; IC10(HepaRG)=13mM; IC10(HepG2)=2mM. Experiments were conducted in triplicate. This dataset is part of the TransQST collection.
Project description:The well-known difference in sensitivity of mice and rats to acetaminophen (APAP) liver injury has been related to differences in the fraction that is bioactivated to the reactive metabolite N-acetyl-p-benzoquinoneimine (NAPQI). Physiologically-based pharmacokinetic modelling was used to identify doses of APAP (300 and 1000 mg/kg in mice and rats, respectively) yielding similar hepatic burdens of NAPQI, to enable the comparison of temporal liver tissue responses under conditions of equivalent chemical insult.