Tetrachloride-induced Liver Fibrosis In Mice Research Articles

Spermine oxidase regulates liver inflammation and fibrosis through β-catenin pathway

BackgroundSpermine oxidase (SMOX), an inducible enzyme involved in the catabolic pathway of polyamine, was found to be upregulated in hepatocellular carcinoma and might be an important oncogene of it in our previous studies. This study attempted to further investigate its relationship with liver inflammation and fibrosis both in vitro and in vivo. MethodsThe effect of SMOX inhibition on LPS-induced inflammatory response in mouse liver cell line AML12 was validated by using small interfering RNA or SMOX inhibitor MDL72527. Western blotting and immunofluorescence were utilized to verify whether LPS could induce β-catenin to transfer into the nucleus and whether it could be reversed by interfering with the expression of SMOX or using SMOX inhibitor. Then, the SMOX inhibitor MDL72527 and SMOX knockout mice were used to verify the hypothesis above in vivo. ResultsThe expression of SMOX could be induced by LPS in AML12 cells. The inhibition of SMOX could inhibit LPS-induced inflammatory response in AML12 cells. LPS could induce β-catenin transfer from cytoplasm to nucleus, while SMOX downregulation or inhibition could partially reverse this process. In vivo intervention with SMOX inhibitor MDL72527 or SMOX knockout mice could significantly improve the damage of liver function, reduce intrahepatic inflammation, inhibit the nuclear transfer of β-catenin in liver tissue, and alleviate carbon tetrachloride-induced liver fibrosis in mice. ConclusionSMOX can promote the inflammatory response and fibrosis of hepatocytes. It provides a new therapeutic strategy for hepatitis and liver fibrosis, inhibiting early liver cancer.

Nicotine aggravates liver fibrosis via α7 nicotinic acetylcholine receptor expressed on activated hepatic stellate cells in mice.

Smoking is a risk factor for liver cirrhosis; however, the underlying mechanisms remain largely unexplored. The α7 nicotinic acetylcholine receptor (α7nAChR) has recently been detected in nonimmune cells possessing immunoregulatory functions. We aimed to verify whether nicotine promotes liver fibrosis via α7nAChR. We used osmotic pumps to administer nicotine and carbon tetrachloride to induce liver fibrosis in wild-type and α7nAChR-deficient mice. The severity of fibrosis was evaluated using Masson trichrome staining, hydroxyproline assays, and real-time PCR for profibrotic genes. Furthermore, we evaluated the cell proliferative capacity and COL1A1 mRNA expression in human HSCs line LX-2 and primary rat HSCs treated with nicotine and an α7nAChR antagonist, methyllycaconitine citrate. Nicotine exacerbated carbon tetrachloride-induced liver fibrosis in mice (+42.4% in hydroxyproline assay). This effect of nicotine was abolished in α7nAChR-deficient mice, indicating nicotine promotes liver fibrosis via α7nAChR. To confirm the direct involvement of α7nAChRs in liver fibrosis, we investigated the effects of genetic suppression of α7nAChR expression on carbon tetrachloride-induced liver fibrosis without nicotine treatment. Profibrotic gene expression at 1.5 weeks was significantly suppressed in α7nAChR-deficient mice (-83.8% in Acta2, -80.6% in Col1a1, -66.8% in Tgfb1), and collagen content was decreased at 4 weeks (-22.3% in hydroxyproline assay). The in vitro analysis showed α7nAChR expression in activated but not in quiescent HSCs. Treatment of LX-2 cells with nicotine increased COL1A1 expression (+116%) and cell proliferation (+10.9%). These effects were attenuated by methyllycaconitine citrate, indicating the profibrotic effects of nicotine via α7nAChR. Nicotine aggravates liver fibrosis induced by other factors by activating α7nAChR on HSCs, thereby increasing their collagen-producing capacity. We suggest the profibrotic effect of nicotine is mediated through α7nAChRs.

Cannabidiol alleviates carbon tetrachloride-induced liver fibrosis in mice by regulating NF-κB and PPAR-α pathways.

Liver fibrosis has become a serious public health problem that can develop into liver cirrhosis and hepatocellular carcinoma and even lead to death. Cannabidiol (CBD), which is an abundant nonpsychoactive component in the cannabis plant, exerts cytoprotective effects in many diseases and under pathological conditions. In our previous studies, CBD significantly attenuated liver injury induced by chronic and binge alcohol in a mouse model and oxidative bursts in human neutrophils. However, the effects of CBD on liver fibrosis and the underlying mechanisms still need to be further explored. A mouse liver fibrosis model was induced by carbon tetrachloride (CCl4) for 10weeks and used to explore the protective properties of CBD and related molecular mechanisms. After the injection protocol, serum samples and livers were used for molecular biology, biochemical and pathological analyses. The results showed that CBD could effectively improve liver function and reduce liver damage and liver fibrosis progression in mice; the expression levels of transaminase and fibrotic markers were reduced, and histopathological characteristics were improved. Moreover, CBD inhibited the levels of inflammatory cytokines and reduced the protein expression levels of p-NF-κB, NF-κB, p-IκBα, p-p38 MAPK, and COX-2 but increased the expression level of PPAR-α. We found that CBD-mediated protection involves inhibiting NF-κB and activating PPAR-α. In conclusion, these results suggest that the hepatoprotective effects of CBD may be due to suppressing the inflammatory response in CCl4-induced mice and that the NF-κB and PPAR-α signaling pathways might be involved in this process.

Yinhuang granule alleviates carbon tetrachloride-induced liver fibrosis in mice and its mechanism.

Liver fibrosis is a formidable global medical challenge, with no effective clinical treatment currently available. Yinhuang granule (YHG) is a proprietary Chinese medicine comprising Scutellariae Radix and Lonicerae Japonicae Flos. It is frequently used for upper respiratory tract infections, pharyngitis, as well as acute and chronic tonsillitis. To investigate the potential of YHG in alleviating carbon tetrachloride (CCl4)-induced liver fibrosis in mice. To induce a hepatic fibrosis model in mice, this study involved intraperitoneal injections of 2 mL/kg of CCl4 twice a week for 4 wk. Meanwhile, liver fibrosis mice in the low dose of YHG (0.4 g/kg) and high dose of YHG (0.8 g/kg) groups were orally administered YHG once a day for 4 wk. Serum alanine/aspartate aminotransferase (ALT/AST) activity and liver hydroxyproline content were detected. Sirius red and Masson's trichrome staining assay were conducted. Real-time polymerase chain reaction, western-blot and enzyme-linked immunosorbent assay were conducted. Liver glutathione content, superoxide dismutase activity level, reactive oxygen species and protein carbonylation amount were detected. The administration of YHG ameliorated hepatocellular injury in CCl4-treated mice, as reflected by decreased serum ALT/AST activity and improved liver histological evaluation. YHG also attenuated liver fibrosis, evident through reduced liver hydroxyproline content, improvements in Sirius red and Masson's trichrome staining, and lowered serum hyaluronic acid levels. Furthermore, YHG hindered the activation of hepatic stellate cells (HSCs) and ameliorated oxidative stress injury and inflammation in liver from CCl4-treated mice. YHG prompted the nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and upregulated the expression of Nrf2-dependent downstream antioxidant genes. In addition, YHG promoted mitochondrial biogenesis in liver from CCl4-treated mice, as demonstrated by increased liver adenosine triphosphate content, mitochondrial DNA levels, and the expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha and nuclear respiratory factor 1. YHG effectively attenuates CCl4-induced liver fibrosis in mice by inhibiting the activation of HSCs, reducing inflammation, alleviating liver oxidative stress damage through Nrf2 activation, and promoting liver mitochondrial biogenesis.

Available and novel plant-based carbon dots derived from Vaccaria Semen carbonisata alleviates liver fibrosis.

Background: Liver fibrosis represents an intermediate stage in the progression of liver disease, and as of now, there exists no established clinical therapy for effective antifibrotic treatment. Purpose: Our aim is to explore the impact of Carbon dots derived from Vaccaria Semen Carbonisata (VSC-CDs) on carbon tetrachloride-induced liver fibrosis in mice. Methods: VSC-CDs were synthesized employing a modified pyrolysis process. Comprehensive characterization was performed utilizing various techniques, including transmission electron microscopy (TEM), multiple spectroscopies, X-ray photoelectron spectroscopy (XPS), and high-performance liquid chromatography (HPLC). A hepatic fibrosis model induced by carbon tetrachloride was utilized to evaluate the anti-hepatic fibrosis effects of VSC-CDs. Results: VSC-CDs, exhibiting a quantum yield (QY) of approximately 2.08%, were nearly spherical with diameters ranging from 1.0 to 5.5nm. The VSC-CDs prepared in this study featured a negative charge and abundant chemical functional groups. Furthermore, these particles demonstrated outstanding dispersibility in the aqueous phase and high biocompatibility. Moreover, VSC-CDs not only enhanced liver function and alleviated liver damage in pathomorphology but also mitigated the extent of liver fibrosis. Additionally, this study marks the inaugural demonstration of the pronounced activity of VSC-CDs in inhibiting inflammatory reactions, reducing oxidative damage, and modulating the TGF-β/Smad signaling pathway. Conclusion: VSC-CDs exerted significant potential for application in nanodrugs aimed at treating liver fibrosis.

Corylin Attenuates CCl4-Induced Liver Fibrosis in Mice by Regulating the GAS6/AXL Signaling Pathway in Hepatic Stellate Cells.

Liver fibrosis is reversible when treated in its early stages and when liver inflammatory factors are inhibited. Limited studies have investigated the therapeutic effects of corylin, a flavonoid extracted from Psoralea corylifolia L. (Fabaceae), on liver fibrosis. Therefore, we evaluated the anti-inflammatory activity of corylin and investigated its efficacy and mechanism of action in ameliorating liver fibrosis. Corylin significantly inhibited inflammatory responses by inhibiting the activation of mitogen-activated protein kinase signaling pathways and the expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha in human THP-1 and mouse RAW264.7 macrophages. Furthermore, corylin inhibited the expression of growth arrest-specific gene 6 in human hepatic stellate cells (HSCs) and the activation of the downstream phosphoinositide 3-kinase/protein kinase B pathway. This inhibited the activation of HSCs and the expression of extracellular matrix proteins, including α-smooth muscle actin and type I collagen. Additionally, corylin induced caspase 9 and caspase 3 activation, which promoted apoptosis in HSCs. Moreover, in vivo experiments confirmed the regulatory effects of corylin on these proteins, and corylin alleviated the symptoms of carbon tetrachloride-induced liver fibrosis in mice. These findings revealed that corylin has anti-inflammatory activity and inhibits HSC activation; thus, it presents as a potential adjuvant in the treatment of liver fibrosis.

Sappanone A Alleviates the Severity of Carbon Tetrachloride-Induced Liver Fibrosis in Mice.

Liver fibrosis is a major challenge to global health because of its various complications, including cirrhosis and hepatocarcinoma, while no effective treatment is available for it. Sappanone A (SA) is a homoisoflavonoid extracted from the heartwood of Caesalpinia sappan Linn. with anti-inflammatory and antioxidant properties. However, the effects of SA on hepatic fibrosis remain unknown. This study aimed to investigate the protective effects of SA on carbon tetrachloride (CCl4)-induced liver fibrosis in mice. To establish a liver fibrosis model, mice were treated intraperitoneally (i.p.) with CCl4 for 4 weeks. SA (25, 50, and 100 mg/kg body weight) was i.p. injected every other day during the same period. Our data indicated that SA decreased liver injury, fibrotic responses, and inflammation due to CCl4 exposure. Consistently, SA reduced oxidative stress and its-mediated hepatocyte death in fibrotic livers. Of note, SA could not directly affect the activation of hepatic stellate cells. Mechanistically, SA treatment lessened oxidative stress-triggered cell death in hepatocytes after CCl4 exposure. SA down-regulated the expression of M1 macrophage polarization markers (CD86 and iNOS) and up-regulated the expression of M2 macrophage polarization markers (CD163, IL-10, and Arg1) in livers and macrophages. Meanwhile, SA induced the activation of peroxisome proliferator-activated receptor gamma (PPARγ). However, decreased inflammatory responses and the trend of M2 macrophage polarization provided by SA were substantially abolished by SR202 (a PPARγ inhibitor) treatment in macrophages. Additionally, SA treatment promoted fibrosis regression. Taken together, our findings revealed that treatment with SA alleviated CCl4-induced fibrotic liver in mice through suppression of oxidative stress-mediated hepatocyte death and promotion of M2 macrophage polarization via PPARγ. Thus, SA might pave the way for a new hepatoprotective agent to treat liver fibrosis.

Artesunate Induces Ferroptosis in Hepatic Stellate Cells and Alleviates Liver Fibrosis via the ROCK1/ATF3 Axis.

Development of fibrosis in chronic liver disease requires activation of hepatic stellate cells (HSCs) and leads to a poor outcome. Artesunate (Art) is an ester derivative of artemisinin that can induce ferroptosis in HSCs, and activated transcriptional factor 3 (ATF3) is an ATF/CREB transcription factor that is induced in response to stress. In this study, we examined the role of the Rho-associated protein kinase 1 (ROCK1)/ATF3 axis in Art-induced ferroptosis in HSCs. HSC activation and ferroptosis were studied in vitro by western blotting, polymerase chain reaction, immunofluorescence, and other assays. ATF3 electrophoretic mobility and ROCK1 protein stability were assayed by western blotting. Immunoprecipitation was used to detect the interaction of ROCK1 and ATF3, as well as ATF3 phosphorylation. A ubiquitination assay was used to verify ROCK1 degradation. Atf3-interfering and Rock1-overexpressing mice were constructed to validate the anti-hepatic fibrosis activity of Art in vivo. Art induced ferroptosis in HSCs following glutathione-dependent antioxidant system inactivation resulting from nuclear accumulation of unphosphorylated ATF3 mediated by ROCK1-ubiquitination in vitro. Art also decreased carbon tetrachloride-induced liver fibrosis in mice, which was reversed by interfering with Atf3 or overexpressing Rock1. The ROCK1/ATF3 axis was involved in liver fibrosis and regulation of ferroptosis, which provides an experimental basis for further study of Art for the treatment of liver fibrosis.

Protective effect of water extracts of Veronicastrum latifolium (Hemsl.) Yamazaki on carbon tetrachloride-induced liver fibrosis in mice and its effect on intestinal flora

Liver fibrosis refers to a reversible event of repair and reconstruction following injury due to various etiologies, and its continuous development will lead to cirrhosis and liver cancer. Abnormal alterations in intestinal microbiota can hasten the development of hepatic fibrosis and damage. Veronicastrum latifolium (Hemsl.) Yamazaki (VLY) is a classic drug applied extensively for managing acute and chronic hepatitis, liver cirrhosis and ascites in ethnic minority areas of Guizhou Province, China, which possesses broad-spectrum pharmacological activities. In view of the crucial role of intestinal microbiota in the development of liver fibrosis, the present study attempted to investigate the effects of VLY aqueous extract on ameliorating CCl4-elicited liver fibrosis in mice and on intestinal microbiota and to explore its possible mechanism. Phytochemical analysis showed that VLY water extract contained a variety of components, particularly rich in organic acids and their derivatives, flavonoids, phenolic acids, nucleotides and their derivatives, carbohydrates and other compounds. VLY water extract remarkably alleviated CCl4-induced liver damage and fibrosis in mice, improved liver histology, and improved liver function abnormalities. VLY water extract also inhibited the activation of hepatic stellate cells and invasion of intrahepatic inflammatory cells. Additionally, sequencing the 16 s rDNA gene revealed that VLY water extract changed the intestinal microbiota composition in liver fibrotic mice. It elevated the Firmicutes/Bacteroidota ratio and enriched the relative Lactobacillus richness, which is capable of mitigating fibrosis and inflammation in impaired liver. In summary, through modulation of inflammation and intestinal microbiota, VLY water extract can reduce the CCl4-elicited liver fibrosis.

Farnesoid X receptor activation is required for the anti-inflammatory and anti-oxidative stress effects of Alisol B 23-acetate in carbon tetrachloride-induced liver fibrosis in mice

Previous studies have shown that Alisol B 23-acetate (23ABA) had potent liver-protection effects, however, its roles and potential mechanisms in carbon tetrachloride (CCl4)-induced liver fibrosis remain to be determined. The present study aimed to investigate the effects of 23ABA on CCl4-induced liver fibrosis and tried to elucidate the underlying mechanisms by focusing on regulating of farnesoid X receptor (FXR). In vivo study found that 23ABA alleviated the CCl4-induced liver injury, and showed no obvious systemic toxicity on mice. 23ABA inhibited the collagen production, decreased sera levels of hyaluronic acid (HA) and procollagen type III (PC-III), lowered mRNA expression of α-smooth muscle actin (α-SMA), fibronectin, collagen I and collagen III in livers of mice. 23ABA inhibited the mRNA expressions and the sera levels of interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α), as well as decreased the expression of cyclooxygenase 2 (COX-2) in fibrotic livers of mice. Besides, 23ABA decreased levels of reactive oxygen species (ROS) and malondialdehyde (MDA), increased glutathione (GSH) level, enhanced activities of superoxide dismutase (SOD) and glutathione reductase (GR) as well as increased mRNA expression of nuclear factor-E2-related factor 2 (Nrf2), glutamate-cysteine ligase, catalytic subunit (GCLC) and glutamate-cysteine ligase, modifier subunit (GCLM). Further study showed that the anti-liver injury and anti-fibrotic effects of 23ABA were abrogated by FXR antagonist guggulsterone (GS) in vivo. In addition, the inhibition effects of 23ABA on liver inflammation and oxidative stress were also weakened by treatment with GS in CCl4-induced fibrotic mice livers. In conclusion, the protective effects of 23ABA against CCl4-induced liver injury and fibrosis, due to FXR-mediated regulation of liver inflammation and oxidative stress.

Effect of mycophenolate mofetil alleviates carbon tetrachloride-induced liver fibrosis in mice.

Hepatic fibrosis is a serious pathological consequence of chronic liver disease. Mycophenolate mofetil (MMF) is a commonly used immunosuppressant after organ transplant. However, the relationship between MMF and hepatic fibrosis remains unclear. This study aims to explore the effect of MMF on hepatic fibrosis in mice and the potential mechanism. A total of 24 mice (male, 8-week old, C57BL/6) were randomly divided into a control group, a MMF group, a carbon tetrachloride (CCl4) group and a CCl4+MMF group (n=6 in each group). After the mice were sacrificed, the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were detected. The liver tissues were taken up for Masson staining and collagen I (COL1) immunohistochemistry. The levels of transforming growth factor-β1 (TGF-β1) and α-smooth muscle actin (α-SMA) were detected by Western blotting. Finally, the levels of mRNA for TGF-β1, α-SMA, and COL1 were detected using real-time PCR. Compared with the CCl4 group, the ALT and AST levels were lower (both P<0.05), the degree of liver fibrosis was alleviated, and the deposition of COL1 in the liver was significantly decreased (P<0.01) in the CCl4+MMF group. Compared with the CCl4 group, the protein expression levels of TGF-β1 and α-SMA were significantly decreased (both P<0.05) and the relative expression levels of TGF-β1, α-SMA and COL1 mRNA in the liver were significantly decreased (all P<0.05) in the CCl4+MMF. MMF could reduce CCl4-induced hepatic fibrosis, which might be related to the inhibition of TGF-β1. This study is expected to provide a target for the treatment of hepatic fibrosis.

Regulating the immune response to carbon tetrachloride-induced liver fibrosis in mice by blocking inducible co-stimulatory molecules and interleukin-33

Objective: To investigate the effects of combined blockade of interleukin-33 (IL-33) and inducible co-stimulatory molecule (ICOS) on carbon tetrachloride-induced chronic liver fibrosis and imbalance of T helper lymphocyte subsets in mice. Methods: There were 40 BALB/c mice in each model and control group. Flow cytometry was used to determine the proportion of Th1/Th2/Th17 cells in the splenic lymphocyte suspension of mice, the expression levels of interferon γ, IL-4, and IL-17 in the splenic lymphocyte suspension of liver fibrosis mice after combined blockade of IL-33 and ICOS, and the pathological changes of liver histopathology in mice with liver fibrosis. Two independent sample t-test was used to compare data between groups. Results: Compared with the non-blocking group, the proportion of Th2 and Th17 cells in the IL-33/ICOS blocking group was significantly down-regulated (Th2: 65.96% ± 6.04% vs. 49.09% ± 7.03%; Th17: 19.17% ± 4.03% vs. 9.56% ± 2.03%), while the proportion of Th1 cells and Th1/Th2 ratio were up-regulated (Th1: 17.14% ± 3.02% vs. 31.93% ± 5.02%; Th1/Th2: 0.28 ± 0.06 vs. 0.62 ± 0.23), and the difference was statistically significant (t = 5.15, 6.03, 7.14, 4.28, respectively, with P < 0.05). After entering the chronic inflammation stage of liver fibrosis in mice (10 weeks), compared with the non-blocking group, the expression levels of IL-4 and IL-17 in the blockade group were significantly down-regulated [IL-4: (84.75 ± 14.35) pg/ ml vs. (77.88 ± 19.61) pg/ml; IL-17: (72.38 ± 15.13) pg/ml vs. (36.38 ± 8.65) pg/ml], while the expression of interferon γ was up-regulated [(37.25 ± 11.51) pg/ml vs. (77.88 ± 19.61) pg/ml], and the difference was statistically significant (t: IL-4: 4.71; IL-17: 5.84; interferon γ: 5.05, respectively, with P < 0.05). Liver histopathological results showed that hepatic necrosis, hepatic lobular structural disorder, and fibrous tissue hyperplasia were significantly lower in the blockade group than those in the non-blocking group at 13 weeks of liver fibrosis. Conclusion: Combined blockade of the ICOS signaling pathway and IL-33 can regulate Th2 and Th17 polarization, down-regulate the inflammatory response, and inhibit or prevent the occurrence and progression of fibrosis.

Hepatocyte-specific knockout of HIF-2α cannot alleviate carbon tetrachloride-induced liver fibrosis in mice.

The effects of hypoxia inducible factor-2α (HIF-2α) deficiency on liver fibrosis have not been demonstrated in a fibrosis model induced by carbon tetrachloride (CCl4). We aimed to examine whether hepatocyte-specific HIF-2α deletion could ameliorate CCl4-induced liver fibrosis in mice. Hepatocyte-specific HIF-2α knockout mice were created using an albumin promoter-driven Cre recombinase. HIF-2α knockout (KO) mice and floxed control wild-type (WT) mice were fed a normal diet (ND) and received either twice weekly intraperitoneal injections of CCl4 solution (CCl4 dissolved in olive oil) or the corresponding amount of olive oil for 8 weeks. The indicators of liver function, glucose and lipid metabolism, and liver histology were compared among the different groups. Hepatocyte-specific HIF-2α knockout had no effect on the growth, liver function, glucose or lipid metabolism in mice. CCl4-treated KO and WT mice had a similar pattern of injury and inflammatory cell infiltration in the liver. Quantification of Masson staining, α-smooth muscle actin (α-SMA) immunohistochemistry, and the hydroxyproline (HYP) content revealed similar liver fibrosis levels between KO and WT mice injected intraperitoneally with CCl4. Immunohistochemistry analysis suggested that HIF-2α was mainly expressed in the portal area and hepatic sinusoids but not in hepatocytes. Bioinformatics analyses further indicated that HIF-2α expression was neither liver specific nor hepatocyte specific, and the effect of HIF-2α in hepatocytes on liver fibrosis may not be as important as that in liver sinuses. Hepatocyte HIF-2α expression may not be a key factor in the initiation of liver fibrogenesis, and hepatocyte-specific deletion of HIF-2α may not be the ideal therapeutic strategy for liver fibrosis.

Direct-acting antivirals sofosbuvir and daclatasvir attenuate carbon tetrachloride-induced liver fibrosis in mice

Background and aimAdvanced liver fibrosis is a major risk for developing hepatocellular carcinoma (HCC) in chronic hepatitis C virus (HCV) patients. Direct-acting antivirals (DAAs) which are used for treating HCV infection, produce more than 90% cure rate but do not seem to diminish the rate of occurrence or recurrence of HCC. This study aimed to investigate the effect of DAAs sofosbuvir (SOF) and daclatasvir (DAC) on carbon tetrachloride (CCl4)-induced fibrotic changes in mice. MethodsEighty adult male Swiss albino mice were randomly allocated into 8 groups (10 mice/group): normal control group, SOF group (receiving SOF 80 mg/kg body weight (BW), oral gavage, daily), DAC group (receiving DAC 30 mg/kg BW, oral gavage, daily), SOF + DAC group (receiving a combination of both, daily), CCl4 model group (receiving CCl4 2 mL/kg BW, intraperitoneal twice weekly) and three CCl4-intoxicated groups receiving either SOF or DAC or their combination. All CCl4 groups received CCl4 for 12 weeks followed by DAAs for another 12 weeks. ResultsCCl4-induced a significant elevation of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and produced histopathological evidence of fibrosis and liver degeneration along with a significant increase (P ≤ 0.001) of the proliferation markers (proliferating cell nuclear antigen (PCNA) and Ki-67), hepatic stellate cells (HSCs) activation markers (alpha-smooth muscle actin (α-SMA) and glial fibrillary acidic protein (GFAP)), fibrosis marker (matrix metalloproteinase-9 (MMP-9)) and pro-inflammatory cytokine (tumor necrosis factor-alpha (TNF-α)). CCl4-intoxicated mice treated with SOF, DAC, or their combination revealed a significant amelioration (P ≤ 0.001) of CCl4-induced elevation of liver enzymes, fibrotic changes, and liver degeneration along with a significant attenuation (P ≤ 0.001) of CCl4-induced upregulation of all tested markers. The effects of SOF, DAC, and their combination on liver enzymes were comparable while the effect of SOF + DAC combination on mitigating CCl4-induced upregulation of the proliferation and HSCs activation markers was significantly stronger than either SOF or DAC alone. As for MMP-9 and TNF-α, the effects of DAC and SOF + DAC combination were comparable and both were more significant than that of SOF alone. ConclusionsSOF and DAC may possess an antifibrotic effect that is independent of their role as antiviral agents against CCl4-induced liver injury. This might exclude the role of DAAs in early occurrence or accelerated recurrence of HCC through the progression of the HCV patients' pre-existing fibrosis. However, HCC patients treated with DAAs should be closely monitored with continuous HCC surveillance during and post-therapy.

CCN2/CTGF promotes liver fibrosis through crosstalk with the Slit2/Robo signaling

Liver fibrosis is the common outcome of many chronic liver diseases, resulting from altered cell-cell and cell-matrix interactions that promote hepatic stellate cell (HSC) activation and excessive matrix production. This study aimed to investigate functions of cellular communication network factor 2 (CCN2)/Connective tissue growth factor (CTGF), an extracellular signaling modulator of the CYR61/CTGF/Nov (CCN) family, in liver fibrosis. Tamoxifen-inducible conditional knockouts in mice and hepatocyte-specific deletion of this gene in rats were generated using the Cre-lox system. These animals were subjected to peri-central hepatocyte damage caused by carbon tetrachloride. Potential crosstalk of this molecule with a new profibrotic pathway mediated by the Slit2 ligand and Roundabout (Robo) receptors was also examined. We found that Ccn2/Ctgf was highly upregulated in periportal hepatocytes during carbon tetrachloride-induced hepatocyte damage, liver fibrosis and cirrhosis in mice and rats. Overexpression of this molecule was observed in human hepatocellular carcinoma (HCC) that were surrounded with fibrotic cords. Deletion of the Ccn2/Ctgf gene significantly reduced expression of fibrosis-related genes including Slit2, a smooth muscle actin (SMA) and Collagen type I during carbon tetrachloride-induced liver fibrosis in mice and rats. In addition, Ccn2/Ctgf and its truncated mutant carrying the first three domains were able to interact with the 7th -9th epidermal growth factor (EGF) repeats and the C-terminal cysteine knot (CT) motif of Slit2 protein in cultured HSC and fibrotic murine livers. Ectopic expression of Ccn2/Ctgf protein upregulated Slit2, promoted HSC activation, and potentiated fibrotic responses following chronic intoxication by carbon tetrachloride. Moreover, Ccn2/Ctgf and Slit2 synergistically enhanced activation of phosphatidylinositol 3-kinase (PI3K) and AKT in primary HSC, whereas soluble Robo1-Fc chimera protein could inhibit these activities. These observations demonstrate conserved cross-species functions of Ccn2/Ctgf protein in rodent livers. This protein can be induced in hepatocytes and contribute to liver fibrosis. Its novel connection with the Slit2/Robo signaling may have therapeutic implications against fibrosis in chronic liver disease.

Antihepatofibrotic effect of Guizhifuling pill on carbon tetrachloride-induced liver fibrosis in mice.

To evaluate the protective effects and the underlying mechanism of Guizhifuling pill (, GZFL) on carbon tetrachloride (CCl)-induced hepatic fibrosis in mice. Male ICR mice by intraperitoneally administered with 20% CCl (mixed 1∶4 in soybean oil) to induce liver fibrosis. Mice that underwent CCl were orally with GZFL. Using hematoxylin and eosin and Masson staining to examine the pathological changes in liver tissue. Serum biochemical parameters, antioxidant enzyme activity and proinflammatory cytokines was assessed. Nuclear factor-kappaB (NF-κB) pathway and nuclear factor-erythroid 2-related factor 2 (Nrf2) family members were evaluated by Western blotting. Our findings indicated that GZFL could effectively suppress the progression of liver fibrosis in mice, which was determined based on the improvement in liver function and reduction of collagen deposition. GZFL treatment also decreased the level of cytokines and increased the activity of antioxidant enzymes in liver tissue. Moreover, GZFL exerted anti-inflammatory and antioxidant effects through regulating the Nrf2-mediated antioxidant system and inhibiting the NF-κB pathway. GZFL may prevent the progression of liver fibrosis by regulating the Nrf2/ heme oxygenase-1 and NF-κB signaling pathways, thereby highlighting its role in the management of liver fibrosis.

MitoQ alleviates carbon tetrachloride-induced liver fibrosis in mice through regulating JNK/YAP pathway.

Liver fibrosis is a pathological wound-healing response caused by chronic liver damage. Mitochondria regulate hepatic energy metabolism and oxidative stress. Accumulating evidence has revealed that increased mitochondrial oxidative stress contributes to the activation of fibrogenesis. However, the roles and underlying mechanisms of mitochondrial oxidative stress in liver fibrosis remain unknown. In this study, C57BL/6 mice were used to establish a model of liver fibrosis via oral gavage with CCl4 treatment for 8weeks. Furthermore, intervention experiments were achieved by CCl4 combined with the intraperitoneal injection of mitoquinone mesylate (mitoQ). We demonstrated that the chronic CCl4 exposure resulted in severe hepatic fibrogenesis and significantly promoted the production of reactive oxygen species (ROS) and mitochondrial abnormalities. Besides, JNK/YAP pathway was also activated. By contrast, the administration of mitoQ markedly inhibited the expression of pro-fibrogenic transforming growth factor-β as well as type I collagen. The antifibrotic effects of mitoQ were also confirmed by hematoxylin and eosin staining and Sirius red staining. Moreover, mitoQ substantially reduced CCl4-induced mitochondrial damage and the release of ROS. Further studies suggested that this protection against liver fibrosis was mechanistically related to the inhibition of phosphorylation of JNK and the nuclear translocation of YAP. In conclusion, these findings revealed that mitoQ attenuated liver fibrosis by inhibiting ROS production and the JNK/YAP signaling pathway. Selective targeting JNK/YAP may serve as a therapeutic strategy for retarding progression of chronic liver disease.

Activation of mitophagy by rapamycin eliminated the accumulation of TDP-43 on mitochondrial and promoted the resolution of carbon tetrachloride-induced liver fibrosis in mice

Liver fibrosis can lead to liver cirrhosis and hepatocellular carcinoma, and no effective treatment is available in clinical practice. Mitochondrial dysfunction is thought to be closely related to the development of liver fibrosis. Recent studies have reported that abnormal accumulation of TDP-43 on mitochondria may interfere with mitochondrial function in neurodegenerative disorders. However, whether aberrant TDP-43 aggregation is also involved in liver fibrosis has not been investigated. In this study, C57/BL6 mice were treated with CCl4 (escalating doses, three times a week) for 8 weeks to establish a model of liver fibrosis. Furthermore, mitophagy intervention experiment was achieved by the activator rapamycin (RAPA). The results demonstrated that chronic CCl4 exposure resulted in severe mitochondrial damage, inflammatory response and hepatic fibrogenesis. Interestingly, abnormal aggregation of TDP-43 on mitochondria was observed. By contrast, RAPA administration could promote the regression of liver fibrosis. Mechanistically, RAPA could eliminate the accumulation of TDP-43 on mitochondrial through enhancing mitophagy, thereby improving mitochondrial function. Taken together, our study revealed that mitochondrial damage induced by abnormal accumulation of TDP-43 has been implicated in the progression of liver fibrosis. Targeted clearance of mitochondrial TDP-43 may lead to the development of some anti-fibrotic therapies.

Adipocyte Fatty Acid Binding Protein Promotes the Onset and Progression of Liver Fibrosis via Mediating the Crosstalk between Liver Sinusoidal Endothelial Cells and Hepatic Stellate Cells.

Development of liver fibrosis results in drastic changes in the liver microenvironment, which in turn accelerates disease progression. Although the pathological function of various hepatic cells in fibrogenesis is identified, the crosstalk between them remains obscure. The present study demonstrates that hepatic expression of adipocyte fatty acid binding protein (A‐FABP) is induced especially in the liver sinusoidal endothelial cells (LSECs) in mice after bile duct ligation (BDL). Genetic ablation and pharmacological inhibition of A‐FABP attenuate BDL‐ or carbon tetrachloride‐induced liver fibrosis in mice associating with reduced collagen accumulation, LSEC capillarization, and hepatic stellate cell (HSC) activation. Mechanistically, elevated A‐FABP promotes LSEC capillarization by activating Hedgehog signaling, thus impairs the gatekeeper function of LSEC on HSC activation. LSEC‐derived A‐FABP also acts on HSCs in paracrine manner to potentiate the transactivation of transforming growth factor β1 (TGFβ1) by activating c‐Jun N‐terminal kinase (JNK)/c‐Jun signaling. Elevated TGFβ1 subsequently exaggerates liver fibrosis. These findings uncover a novel pathological mechanism of liver fibrosis in which LSEC‐derived A‐FABP is a key regulator modulating the onset and progression of the disease. Targeting A‐FABP may represent a potential approach against liver fibrosis.

Hepatoprotective effect of piceatannol against carbon tetrachloride-induced liver fibrosis in mice.

Piceatannol (3,5,3',4'-trans-tetrahydroxystilbene) is a natural analog and a metabolite of resveratrol present in grapes and red wine. Previous studies have reported that piceatannol exerts a broad spectrum of health benefits including antioxidant, anti-inflammatory, chemopreventive, and neuroprotective effects. However, little is known about the hepatoprotective effect of piceatannol against toxin-induced liver fibrosis. Therefore, the objective of this study is to evaluate the protective effect of piceatannol in a mouse model of CCl4-induced hepatic fibrosis. Oral administration of piceatannol significantly improved the hepatic functions of CCl4-treated mice in both therapeutic and preventive models. Additionally, the immunohistochemical staining results revealed that collagen deposition in CCl4-injected mice was significantly reduced by treatment with piceatannol. Moreover, piceatannol remarkably suppressed the expressions of collagen I, α-smooth muscle protein (α-SMA), and tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) induced by CCl4. The anti-fibrotic mechanism of piceatannol was associated with the regulation of the transforming growth factor-β (TGF-β)/Smad signaling pathway. Finally, piceatannol also profoundly alleviated CCl4-induced hepatic oxidative damage by elevating the level of glutathione and catalase activity. Altogether, our current findings suggest that piceatannol may serve as a bioactive agent that inhibits or alleviates toxic-induced fibroproliferative diseases, especially in the prevention of liver fibrosis.