CCl4-induced Liver Injury Mouse Model Research Articles

Inhibition of intrahepatic monocyte recruitment by Cenicriviroc and extracellular matrix degradation by MMP1 synergistically attenuate liver inflammation and fibrogenesis in vivo

The chemokine (CCL)-chemokine receptor (CCR2) interaction, importantly CCL2-CCR2, involved in the intrahepatic recruitment of monocytes upon liver injury promotes liver fibrosis. CCL2-CCR2 antagonism using Cenicriviroc (CVC) showed promising results in several preclinical studies. Unfortunately, CVC failed in phase III clinical trials due to lack of efficacy to treat liver fibrosis. Lack of efficacy could be attributed to the fact that macrophages are also involved in disease resolution by secreting matrix metalloproteinases (MMPs) to degrade extracellular matrix (ECM), thereby inhibiting hepatic stellate cells (HSCs) activation. HSCs are the key pathogenic cell types in liver fibrosis that secrete excessive amounts of ECM causing liver stiffening and liver dysfunction. Knowing the detrimental role of intrahepatic monocyte recruitment, ECM, and HSCs activation during liver injury, we hypothesize that combining CVC and MMP (MMP1) could reverse liver fibrosis. We evaluated the effects of CVC, MMP1 and CVC + MMP1 in vitro and in vivo in CCl4-induced liver injury mouse model. We observed that CVC + MMP1 inhibited macrophage migration, and TGF-β induced collagen-I expression in fibroblasts in vitro. In vivo, MMP1 + CVC significantly inhibited normalized liver weights, and improved liver function without any adverse effects. Moreover, MMP1 + CVC inhibited monocyte infiltration and liver inflammation as confirmed by F4/80 and CD11b staining, and TNFα gene expression. MMP1 + CVC also ameliorated liver fibrogenesis via inhibiting HSCs activation as assessed by collagen-I staining and collagen-I and α-SMA mRNA expression. In conclusion, we demonstrated that a combination therapeutic approach by combining CVC and MMP1 to inhibit intrahepatic monocyte recruitment and increasing collagen degradation respectively ameliorate liver inflammation and fibrosis.

Honokiol inhibits epithelial-mesenchymal transition and hepatic fibrosis via activation of Ecadherin/GSK3β/JNK and inhibition of AKT/ERK/p38/β-catenin/TMPRSS4 signaling axis.

Though Honokiol was known to have anti-inflammatory, antioxidant, anticancer, antithrombotic, anti-viral, metabolic, antithrombotic, and neurotrophic activities, the underlying mechanisms of Honokiol on epithelial-mesenchymal transition (EMT) mediated liver fibrosis still remain elusive so far. Anti-EMT and antifibrotic effects of Honokiol were explored in murine AML-12 hepatocyte cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, wound healing assay, Western blotting and also in CCl4-induced liver injury mouse model by immunohistochemistry. Honokiol significantly suppressed transforming growth factor β1 (TGF-β1)-induced EMT and migration of AML-12 cells along with decreased EMT phenotypes such as loss of cell adhesion and formation of fibroblast like mesenchymal cells in TGF-β1-treated AML-12 cells. Consistently, Honokiol suppressed the expression of Snail and transmembrane protease serine 4 (TMPRSS4), but not p-Smad3, and activated E-cadherin in TGF-β1-treated AML-12 cells. Additionally, Honokiol reduced the expression of β-catenin, p-AKT, p-ERK, p-p38 and increased phosphorylation of glycogen synthase kinase 3 beta (GSK3β) and JNK in TGF-β1-treated AML-12 cells via TGF-β1/nonSmad pathway. Conversely, GSK3β inhibitor SB216763 reversed the ability of Honokiol to reduce Snail, β-catenin and migration and activate E-cadherin in TGF-β1-treated AML-12 cells. Also, Honokiol suppressed hepatic steatosis and necrosis by reducing the expression of TGF-β1 and α-SMA in liver tissues of CCl4 treated mice. These findings provide scientific evidence that Honokiol suppresses EMT and hepatic fibrosis via activation of E-cadherin/GSK3β/JNK and inhibition of AKT/ERK/p38/β-catenin/TMPRSS4 signaling axis.

Antioxidant, hepatoprotective and antifungal activities of black pepper (Piper nigrum L.) essential oil

The essential oil extracted from the black Piper nigrum L. (BPEO) was analyzed for antioxidant, hepatoprotective and antifungal activities. BPEO is rich in total phenolics, total flavonoids and proanthocyanidins, and showed good free radicals and lipid peroxidation scavenging capacities. In a CCl4-induced liver injury mice model, the BPEO treated groups showed increases in the catalase (CAT), glutathione (GSH) and total superoxide dismutase (T-SOD) activities present in the liver and kidney, and reverses the CCl4-elevated total bilirubin (TBIL), glutamate pyruvate transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AKP) and malondialdehyde (MDA) level, which were confirmed in further analyses of kidney tissue sections. BPEO can effectively inhibit the growth of Aspergillus flavus spoilage fungus in maize. Further analyses indicated that BPEO disrupt the permeability barrier of the cell membrane and lead to mitochondrial dysfunction in A. flavus. Therefore, the current study proved BPEO’s potential as hepatoprotective products and natural food preservatives.

Androgen aggravates liver fibrosis by activation of NLRP3 inflammasome in CCl4-induced liver injury mouse model.

Studies have shown that there are differences between the sexes regarding to the occurrence and development of liver diseases, which may be associated with sex hormones. However, the mechanisms behind it are largely unknown. In this study, we first investigated the differences of liver injury between male and female mice, using the CCl4-induced liver injury mouse model. It showed that the liver damage of male mice was much more severe than that of female mice. Both the acute injury and fibrosis of the liver were reduced when androgens were depleted by castration of male mice. The vulnerability of male liver was associated with testis endocrine and excessive activation of inflammatory response in the liver. Castrated male mice with testosterone supplementation showed aggravated liver inflammatory response and fibrosis. The activity of NOD-like receptor protein 3 (NLRP3) inflammasome was increased when testosterone supplementation was provided. However, the enhanced inflammatory response and fibrosis due to testosterone supplementation were negated by inhibiting the activation of NLRP3 using the specific small molecule inhibitor MCC950. It suggests that testosterone is a key factor that influences liver injury by regulating the NLRP3 inflammasome activation-mediated inflammatory response.

A high-throughput targeted metabolomics method for the quantification of 104 non-polar metabolites in cholesterol, eicosanoid, and phospholipid metabolism: application in the study of a CCl4-induced liver injury mouse model.

Much evidence suggested that cholesterol, eicosanoid and phospholipid metabolism plays crucial roles in inflammation, atherosclerosis, carcinogenesis, etc. Therefore, fast and accurate quantification of the metabolites in these metabolic pathways is necessary for discovering the molecular mechanisms and biomarkers of related diseases. In this assay, ultra-high performance liquid chromatography combined with triple quadrupole mass spectrometry platform (UPLC-QqQ-MS) based protocols were developed to simultaneously quantify a total of 104 key metabolites including 32 phospholipids (PLs), 44 eicosanoids (EAs), 28 oxysterols and bile acids (BAs), within 15 minutes. Validation results showed that this method is stable, sensitive and accurate for analyzing different matrix samples. Next, this method was used to characterize the metabolic phenotype of a CCl4-induced liver injury model. The results showed that polyunsaturated fatty acids (PUFA) and PUFA acyl-phospholipids (PFA-PLs) were down-regulated and the levels of saturated fatty acyl-phospholipids (SFA-PLs) and EAs were up-regulated in both the liver tissue and plasma of the CCl4-injury group. BAs were up-regulated in plasma, but down-regulated in the liver tissue of the CCl4-injury group. Immunohistochemistry assay demonstrated that the expression levels of cytosolic phospholipase A2 (cPLA2), phosphorylated cytosolic phospholipase A2 (p-cPLA2), secreted phospholipase A2-IIA (sPLA2-IIA) and lysophosphatidylcholine acyltransferase 1 (LPCAT1) were all up-regulated. According to our results, we drew a diagram of the CCl4-induced acute liver injury molecular mechanism. Moreover, we found that the area under the receiver operating characteristic curve (AUC) of 7α-hydroxycholesterol and 7β-hydroxycholesterol was 1.0, which indicates that the two metabolites have significant potential for the diagnosis of acute liver injury. The outstanding performance of this analytical method proves its further usefulness for mechanism studies and biomarker screening of related diseases.

Neutralization of chemokine CXCL14 (BRAK) expression reduces CCl4 induced liver injury and steatosis in mice

Using mouse gene expression microarray analysis, we earlier obtained dynamic profiles of whole genome expression in the CCl4-induced liver injury mouse model. CXCL14 expression was increased in the liver injury phase and returned to normal after liver regeneration suggesting its involvement in the liver injury or regeneration regulation. The role of CXCL14 in liver injury was investigated. The dynamic of CXCL14 transcription was analyzed in CCl4-induced mouse liver damage by qRT-PCR. Plasmid mediated CXCL14 overexpression and antibody neutralization of endogenous CXCL14 were used to demonstrate its effects and mechanisms on CCl4-induced liver injury and acute liver failure. We showed that CXCL14 expression was immediately upregulated post CCl4 injection with a dose-dependent response. CXCL14 over-expression aggravated CCl4-induced liver injuries, evidenced by enhanced acidophilic change and necrosis of hepatocyte, increased fat deposition in hepatocytes (P<0.01), and inhibited hepatocyte proliferation (P<0.01). On the contrary, anti-CXCL14 antibody treatment reduced the severity of CCL4-induced liver injuries Significant reductions in hepatic necrosis area (P<0.05), the liver fat deposition (P<0.01), and the lipid peroxidation measured by serum MDA (P<0.05) were observed. Importantly, the antibody treatment reduced the mouse mortality caused by CCl4-induced liver failure (P<0.05). The data suggest that CXCL14 and its receptor present potential targets for the treatment of liver diseases.