Effect of interferon-gamma on hepatic fibrosis in chronic hepatitis B virus infection: a randomized controlled study

Cytokines Expression Compared to the Determinants of Cellular Apoptosis Prominently Attributes to the Deleterious Effects of 'A' Determinant Surface Gene Mutations in HBV Transfected Hepatoma Cell Line

BACKGROUND

Previous studies have explored the role of AKT protein in anti-apoptotic/proliferative activities. However, there has been a lack of information regarding the role of Akt in association with cytokines expression in HBV-related (wild type HBV and HBV with mutations of 'a' determinant region) studies either in the case of HBV infection or in transfected hepatoma cells. The present study tries to determine the role of Akt and cytokines expression in the presence of small surface gene mutants in the hepatoma cell line.

METHODS

Mutations of 'a' determinant region, viz. sA128V and sG145R, were created in wild-type pHBV1.3 by site-directed mutagenesis and transfected in hepatoma cell line. Secretory levels of HBsAg in the wild type as well as in both the mutants were analyzed by ELISA. Apoptotic analysis of transfected cells was studied by flow cytometry. Expression analysis of Akt and cytokines (TNF-alpha, IL-6, and IFN-gamma) was done by qPCR.

RESULTS

The presence of significantly more alive cells in sG145R than sA128V transfected cells may be due to the up-regulation of the Akt gene expression. Cytokines expression was nearly similar between sA128V and wild-type pHBV1.3 transfected cells. Presence of sG145R showed dramatically high cytokines expression than sA128V and wild-type pHBV1.3.

CONCLUSION

Cytokines expression predominantly contributes to the detrimental effects associated with the 'a' determinant region mutations particularly sG145R mutant. It may also be inferred that mechanisms associated with cellular apoptosis apparently do not play any major role to assign the 'a' determinant small surface gene mutation(s) for their pathological outcome.

Chinese Herbal Formula Ruangan Granule Enhances the Efficacy of Entecavir to Reverse Advanced Liver Fibrosis/Early Cirrhosis in Patients with Chronic HBV Infection: A Multicenter, Randomized Clinical Trial

BACKGROUND

Nucleotide analogs treatment can reverse liver fibrosis in chronic hepatitis B (CHB). However, it has limited effect on fibrosis resolution in patients with CHB, particularly in preventing progression to hepatocellular carcinoma (HCC). Ruangan granule (RG), a Chinese herbal formula, has proven to produce a therapeutic effect against liver fibrosis in animal experiment. Thus, we aimed to evaluate the effect of our Chinese herbal formula (RG) combined with entecavir (ETV) to reverse advanced liver fibrosis/early cirrhosis from CHB.

METHODS

A total of 240 CHB patients with histologically confirmed advanced liver fibrosis/early cirrhosis from 12 centers were randomly and blindly allocated to consume either ETV (0.5mg/day) plus RG (2 times/day) or control (ETV) for 48 weeks (wk) treatment. Changes in histopathology, serology and imageology were observed. Liver fibrosis reversion, defined as a reduction in the Knodell HAI score by ≥2 points and Ishak score by ≥1 grade, was assessed.

RESULTS

The rate of fibrosis regression and inflammation remission after 48 wk of treatment in histopathology was significantly higher in the ETV + RG group (38.73% vs. 23.94%, P=0.031). The ultrasonic semiquantitative scores decreased by ≥2 points and were 41 (28.87%) and 15 (21.13%) in the ETV+RG and ETV groups, respectively (P=0.026). The ETV+RG group had a significantly lower Fibrosis-4 score (FIB-4) index (P=0.028). There was a significant difference between the ETV+RG and ETV groups in the liver function normalization rate (P <0.01). Moreover, ETV plus RG combination treatment further reduced the risk of HCC in median 55-month follow-up (P <0.01).

CONCLUSIONS

This study illustrates that the Chinese herbal formula RG with ETV can improve advanced liver fibrosis/early cirrhosis regression in patients with CHB, further reducing the risk of HCC.

Resistance of Human Liver Mesenchymal Stem Cells to FAS-Induced Cell Death

Mesenchymal stem cells (MSCs) have a pronounced therapeutic potential in various pathological conditions. Though therapeutic effects of MSC transplantation have been studied for a long time, the underlying mechanisms are still not clear. It has been shown that transplanted MSCs are rapidly eliminated, presumably by apoptosis. As the mechanisms of MSC apoptosis are not fully understood, in the present work we analyzed MSC sensitivity to Fas-induced apoptosis using MSCs isolated from the biopsies of liver fibrosis patients (L-MSCs). The level of cell death was analyzed by flow cytometry in the propidium iodide test. The luminescent ATP assay was used to measure cellular ATP levels; and the mitochondrial membrane potential was assessed using the potential-dependent dye JC-1. We found that human L-MSCs were resistant to Fas-induced cell death over a wide range of FasL and anti-Fas mAb concentrations. At the same time, intrinsic death signal inducers CoCl₂ and staurosporine caused apoptosis of L-MSCs in a dose-dependent manner. Despite the absence of Fas-induced cell death treatment of L-MSCs with low concentrations of FasL or anti-Fas mAb resulted in a cellular ATP level decrease, while high concentrations of the inducers caused a decline of the mitochondrial membrane potential. Pre-incubation of L-MSCs with the pro-inflammatory cytokine TNF-α did not promote L-MSC cell death. Our data indicate that human L-MSCs have increased resistance to receptor-mediated cell death even under inflammatory conditions.

Familial hemophagocytic lymphohistiocytosis hepatitis is mediated by IFN-γ in a predominantly hepatic-intrinsic manner

Interferon gamma (IFN-γ) is the main cytokine driving organ dysfunction in Familial Hemophagocytic Lymphohistiocytosis (FHL). Blockade of IFN-γ pathway ameliorates FHL hepatitis, both in animal models and in humans with FHL. Hepatocytes are known to express IFN-γ receptor (IFN-γ-R). However, whether IFN-γ induced hepatitis in FHL is a lymphocyte or liver intrinsic response to the cytokine has yet to be elucidated. Using a IFNgR-/- bone marrow chimeric model, this study showed that non-hematopoietic IFN-γ response is critical for development of FHL hepatitis in LCMV-infected Prf1-/- mice. Lack of hepatic IFN-γ responsiveness results in reduced hepatitis as measured by hepatomegaly, alanine aminotransferase (ALT) levels and abrogated histologic endothelial inflammation. In addition, IFN-γ non-hematopoietic response was critical in activation of lymphocytes by soluble interleukin 2 receptor (sIL-2r) and recruitment of CD8+ effector T lymphocytes (CD8+ CD44hi CD62Llo) (Teff) and inflammatory monocytes. Lastly, non-hematopoietic IFN-γ response results in increased hepatic transcription of type 1 immune response and oxidative stress response pathways, while decreasing transcription of genes involved in extracellular matrix (ECM) production. In summary, these findings demonstrate that there is a hepatic transcriptional response to IFN-γ, likely critical in the pathogenesis of FHL hepatitis and hepatic specific responses could be a therapeutic target in this disorder.

Ongoing Clinical Trials in Aging-Related Tissue Fibrosis and New Findings Related to AhR Pathways

Fibrosis is a pathological manifestation of wound healing that replaces dead/damaged tissue with collagen-rich scar tissue to maintain homeostasis, and complications from fibrosis contribute to nearly half of all deaths in the industrialized world. Ageing is closely associated with a progressive decline in organ function, and the prevalence of tissue fibrosis dramatically increases with age. Despite the heavy clinical and economic burden of organ fibrosis as the population ages, to date, there is a paucity of therapeutic strategies that are specifically designed to slow fibrosis. Aryl hydrocarbon receptor (AhR) is an environment-sensing transcription factor that exacerbates aging phenotypes in different tissues that has been brought back into the spotlight again with economic development since AhR could interact with persistent organic pollutants derived from incomplete waste combustion. In addition, gut microbiota dysbiosis plays a pivotal role in the pathogenesis of numerous diseases, and microbiota-associated tryptophan metabolites are dedicated contributors to fibrogenesis by acting as AhR ligands. Therefore, a better understanding of the effects of tryptophan metabolites on fibrosis modulation through AhR may facilitate the exploitation of new therapeutic avenues for patients with organ fibrosis. In this review, we primarily focus on how tryptophan-derived metabolites are involved in renal fibrosis, idiopathic pulmonary fibrosis, hepatic fibrosis and cardiac fibrosis. Moreover, a series of ongoing clinical trials are highlighted.

IL-1β-activated mTORC2 promotes accumulation of IFN-γ+ γδ T cells by upregulating CXCR3 to restrict hepatic fibrosis

Liver fibrosis represents a severe stage of liver damage, with hallmarks of inflammation, hepatic stellate cell activation, and extracellular matrix accumulation. Although previous studies demonstrated γδ T cells are involved in liver fibrosis, the precise role and mechanisms of γδ T cells migrating to fibrotic liver have not been elucidated. Here, we aim to investigate the functional subsets of γδ T cells in hepatic fibrosis and to further explore the underlying causes and drivers of migration. In this study, we observed that γδ T cells accumulate in fibrotic liver. Adoptive transfer of γδ T, especially Vγ4 γδ T subset, can significantly alleviate liver fibrosis. In addition, CCl4 treatment also leads to activation of mTOR signaling in γδ T cells. Genetic deletion of the Rictor gene, but not Raptor, in γδ T cells markedly exacerbated liver fibrosis. Mechanistically, CCl4-induced liver injury causes macrophage accumulation in the liver, and IL-1β produced by macrophages promotes mTORC2 signaling activation in γδ T cells, which upregulates T-bet expression and eventually promotes CXCR3 transcription to drive γδ T cell migration. Moreover, hepatic γδ T cells ameliorated liver fibrosis by cytotoxicity against activated hepatic stellate cells in FasL-dependent manner, and secrete IFN-γ to inhibit the differentiation of pro-fibrotic Th17 cells. Thus, IL-1β-activated mTORC2 signaling in γδ T cells upregulates CXCR3 expression, which is critical for IFN-γ+ γδ T cells migration into the liver and amelioration of liver fibrosis. Our findings indicate that targeting the mTORC2 or CXCR3 in γδ T cells could be considered as a promising approach for γδ T cell immunotherapy against liver fibrosis.

Presence of Liver Inflammation in Asian Patients With Chronic Hepatitis B With Normal ALT and Detectable HBV DNA in Absence of Liver Fibrosis

Liver biopsies are recommended to exclude significant liver inflammation in patients with chronic hepatitis B (CHB) with elevated HBV DNA but without other indications for antiviral treatment. We aimed to investigate the proportions and determinants of significant inflammation in Asian patients with CHB with detectable HBV DNA. We conducted a cross‐sectional study that retrospectively included 581 patients with CHB with detectable HBV DNA who had undergone liver biopsy. Liver inflammation and fibrosis were staged by Scheuer’s classification. Significant inflammation and significant fibrosis were defined as G ≥ 2 and S ≥ 2, respectively. There were 179 (30.8%) patients with alanine aminotransferase (ALT) < 1 × upper limit of normal (ULN), 205 (35.3%) patients with ALT 1‐2 × ULN, and 197 (33.9%) patients with ALT > 2 × ULN. A total of 397 (68.3%) patients had significant inflammation, and 340 (58.5%) patients had significant fibrosis. Significant inflammation was found in 85% of patients with significant fibrosis and in 44.8% of patients without significant fibrosis. Furthermore, 28.7% of patients with CHB with detectable HBV DNA and normal ALT in the absence of significant fibrosis had significant inflammation. Moderate HBV DNA (5‐7 log₁₀ IU/mL) was a risk factor for significant inflammation (odds ratio [OR] 6.929, 95% confidence interval [CI] 2.830‐16.966, P < 0.001) in patients with CHB with detectable HBV DNA, especially for patients with detectable HBV DNA and normal ALT in the absence of significant fibrosis (adjusted OR 13.161, 95% CI 1.026‐168.889, P = 0.048). Conclusion: A high proportion of CHB patients with detectable HBV DNA and normal ALT in the absence of significant fibrosis have significant liver inflammation. Liver biopsies are recommended to evaluate liver inflammation in such patients, especially for those with moderate HBV DNA.

Intracellular interferon signalling pathways as potential regulators of covalently closed circular DNA in the treatment of chronic hepatitis B

Infection with the hepatitis B virus (HBV) is still a major global health threat as 250 million people worldwide continue to be chronically infected with the virus. While patients may be treated with nucleoside/nucleotide analogues, this only suppresses HBV titre to sub-detection levels without eliminating the persistent HBV covalently closed circular DNA (cccDNA) genome. As a result, HBV infection cannot be cured, and the virus reactivates when conditions are favorable. Interferons (IFNs) are cytokines known to induce powerful antiviral mechanisms that clear viruses from infected cells. They have been shown to induce cccDNA clearance, but their use in the treatment of HBV infection is limited as HBV-targeting immune cells are exhausted and HBV has evolved multiple mechanisms to evade and suppress IFN signalling. Thus, to fully utilize IFN-mediated intracellular mechanisms to effectively eliminate HBV, instead of direct IFN administration, novel strategies to sustain IFN-mediated anti-cccDNA and antiviral mechanisms need to be developed. This review will consolidate what is known about how IFNs act to achieve its intracellular antiviral effects and highlight the critical interferon-stimulated gene targets and effector mechanisms with potent anti-cccDNA functions. These include cccDNA degradation by APOBECs and cccDNA silencing and transcription repression by epigenetic modifications. In addition, the mechanisms that HBV employs to disrupt IFN signalling will be discussed. Drugs that have been developed or are in the pipeline for components of the IFN signalling pathway and HBV targets that detract IFN signalling mechanisms will also be identified and discussed for utility in the treatment of HBV infections. Together, these will provide useful insights into design strategies that specifically target cccDNA for the eradication of HBV.

Attenuation of Dupuytren's fibrosis via targeting of the STAT1 modulated IL-13Rα1 response

Fibrotic disorders represent common complex disease pathologies that are therapeutically challenging. Inflammation is associated with numerous fibrotic pathogeneses; however, its role in the multifaceted mechanisms of fibrosis remains unclear. IL-13 is implicated in aberrant responses involved in fibrotic disease, and we aimed to understand its role in the inflammatory processes of a common fibrotic disorder, Dupuytren's disease. We demonstrated T-cells produced IFN-g, which induced IL-13 secretion from mast cells and up-regulated IL-13Ra1 on fibroblasts, rendering them more reactive to IL-13. Consequently, diseased myofibroblasts demonstrated enhanced fibroproliferative effects upon IL-13 stimulation. We established IFN-g and IL-13 responses involved STAT dependent pathways, and STAT targeting (tofacitinib) could inhibit IL-13 production from mast cells, IL-13Ra1 up-regulation in fibroblasts and fibroproliferative effects of IL-13 on diseased myofibroblasts. Accordingly, utilizing Dupuytren's as an accessible human model of fibrosis, we propose targeting STAT pathways may offer previously unidentified therapeutic approaches in the management of fibrotic disease.

The effects of nucleoside/nucleotide analogues on host immune cells: the baseline for future immune therapy for HBV?

HBV is a non-cytopathic virus and the progression of liver fibrosis is attributed to the host immune response. Complete suppression of viral replication using nucleotide or nucleoside analogues (NUCs) can prevent most complications related to chronic HBV infection. Unfortunately, antiviral treatment has to be administered lifelong to the majority of patients as HBV persists in the hepatocytes. However, although NUCs are very frequently administered in clinical practice, their effects on vital parts of the host immune response to HBV are not well established. In this review we summarize the currently available data gathered from longitudinal studies that investigated treatment-associated alterations of HBV-specific CD4⁺ and CD8⁺ T-cells, regulatory T-cells and natural killer (NK) cells. These observations are important, as they can guide the design of studies that investigate the efficacy of new immune therapeutic agents. Novel experimental compounds will likely be added to ongoing NUC treatment, which leads to a functional cure in only a small minority of patients.

Evaluation of the antifibrotic potency by knocking down SPARC, CCR2 and SMAD3

BACKGROUND

The genes of SPARC, CCR2, and SMAD3 are implicated in orchestrating inflammatory response that leads to fibrosis in scleroderma and other fibrotic disorders. The aim of the studies is to evaluate synergistic anti-fibrotic potency of the siRNAs of these genes.

METHODS

The efficacy of the siRNA-combination was evaluated in bleomycin-induced mouse fibrosis. The pathological changes of skin and lungs of the mice were assessed by hematoxylin and eosin and Masson's trichrome stains. The expression of inflammation and fibrosis associated genes and proteins in the tissues were assessed by real-time RT-PCR, RNA sequencing, Western blots and ELISA. Non-crosslinked fibrillar collagen was measured by the Sircol colorimetric assay.

FINDINGS

The applications of the combined siRNAs in bleomycin-induced mice achieved favorable anti-inflammatory and anti-fibrotic effects. Activation of fibroblasts was suppressed in parallel with inhibition of inflammation evidenced by reduced inflammatory cells and proinflammatory cytokines in the BALF and/or the tissues by the treatment. Aberrant expression of the genes normally expressed in fibroblasts, monocytes/ macrophage, endothelial and epithelial cells were significantly restrained after the treatment. In addition, transcriptome profiles indicated that some bleomycin-induced alterations of multiple biological pathways were recovered to varying degrees by the treatment.

INTERPRETATION

The application of the combined siRNAs of SPARC, CCR2, and SMAD3 genes ameliorated inflammation and fibrosis in bleomycin-induced mice. It systemically reinstated multiple biopathways, probably through controlling on different cell types including fibroblasts, monocytes/macrophages, endothelial cells and others. The multi-target-combined therapeutic approach examined herein may represent a novel and effective therapy for fibrosis.

Antioxidant and anti-inflammatory activities of berberine attenuate hepatic fibrosis induced by thioacetamide injection in rats

Berberine (BBR) is an isoquinoline alkaloid extracted from the roots, rhizomes and stems of coptis. Liver fibrosis is a worldwide health problem with no established therapy until now. The aim of our study is to investigate the efficacy of BBR on hepatic fibrosis induced in rats and to uncover other mechanisms. Rats were injected with thioacetamide (TAA) (200 mg/kg, i.p) twice per week for 6 weeks to induce fibrosis. Treated groups were gavaged with BBR (50 mg/kg/day, p.o) simultaneously with TAA injection. Hepatic antioxidant enzymes (catalase, SOD, GPx) were assessed in hepatic homogenate. Their activities were attenuated by TAA injection and elevated by BBR administration. Additionally, serum IL-6 and mRNA levels of IL-1β, IL-6, IL-10 and IFN-γ were evaluated as inflammatory markers. Our results showed that BBR suppressed the inflammation induced by TAA injection. Tissue expression of α-SMA (marker of activated HSCs), TGF-β1 and fibronectin were measured by immunohistochemistry as well as mRNA expressions of TGF-β1 and fibronectin were quantified as fibrotic markers. The collagen deposition in hepatic tissues was assessed by Masson's trichome staining. BBR significantly alleviated TGF-β1 production, decreased collagen and fibronectin deposition and consequently attenuated hepatic fibrogenesis. Akt pathway controls cell survival, proliferation, migration and adhesion. The relative phosphorylation of Akt was determined in hepatic homogenates that was increased with TAA injection and decreased by BBR treatment. Inhibition of Akt pathway has been linked to the intrinsic pathway of apoptosis. Caspase-3, caspase-9, Bcl-2 and Bax were quantified as apoptotic markers using qPCR and also caspase-3 by immunohistochemistry. BBR-treated rats showed an increase in the expression of apoptotic markers. Moreover, BBR-treated rats showed restoration of normal liver lobular architecture as shown by H&E staining. In conclusion, BBR is a potential therapeutic candidate for liver fibrosis owing to its antioxidant and anti-inflammatory activities.

The influence of hypoxia and IFN-γ on the proteome and metabolome of therapeutic mesenchymal stem cells

Over the past 15 years, mesenchymal stem cells (MSCs) have been assessed for their capacity to suppress inflammation and promote tissue repair. Regardless of whether the cells are primed (exposed to instructive cues) before administration, their phenotype will respond to environmental signals present in the pathophysiological setting being treated. Since hypoxia and inflammation coexist in the settings of acute injury and chronic disease we sought to explore how the proteome and metabolome of MSCs changes when cells were exposed to 48 h of 1% oxygen, interferon gamma (IFN-γ), or both cues together. We specifically focused on changes in cell metabolism, immune modulation, extracellular matrix secretion and modification, and survival capacity. IFN-γ promoted expression of anti-pathogenic proteins and induced MSCs to limit inflammation and fibrosis while promoting their own survival. Hypoxia instead led to cell adaptation to low oxygen, including upregulation of proteins involved in anaerobic metabolism, autophagy, angiogenesis, and cell migration. While dual priming resulted in additive effects, we also found many instances of synergy. These data lend insight to how MSCs may behave after administration to a patient and suggest how priming cells beforehand could improve their therapeutic capacity.

Are we any closer to treating liver fibrosis (and if no, why not)?

This review provides a personal view on anti-fibrosis therapy in the liver. The worst clinical consequence of liver fibrosis is the development of liver cirrhosis and portal hypertension. Etiology is a decisive factor which determines patterns of fibrous septa and subsequent vascular remodeling, which is essential for the development of portal hypertension. Removing or controlling the disease-causing agent, i.e. anti-viral treatment for hepatitis, is the essential first step for treating chronic liver diseases and can reverse fibrosis in some settings. However, removing etiology is not always sufficient to prevent fibrosis from progressing towards cirrhosis and portal hypertension. In liver diseases such as severe alcoholic hepatitis and massive parenchymal loss, the formation of vascular anastomoses between portal to central veins based on bridging fibrosis results in cirrhosis and portal hypertension. For these patients, anti-fibrotic treatment is crucial and urgent. Unfortunately, a lack of understanding how fibrosis contributes to vascular remodeling caused by and combined with a lack of suitable experimental models that recapitulate human liver diseases, has hampered the development of successful anti-fibrotic drugs for clinical use to date.

Current Perspectives Regarding Stem Cell-Based Therapy for Liver Cirrhosis

Liver cirrhosis is a major cause of mortality and a common end of various progressive liver diseases. Since the effective treatment is currently limited to liver transplantation, stem cell-based therapy as an alternative has attracted interest due to promising results from preclinical and clinical studies. However, there is still much to be understood regarding the precise mechanisms of action. A number of stem cells from different origins have been employed for hepatic regeneration with different degrees of success. The present review presents a synopsis of stem cell research for the treatment of patients with liver cirrhosis according to the stem cell type. Clinical trials to date are summarized briefly. Finally, issues to be resolved and future perspectives are discussed with regard to clinical applications.

Naringin attenuates thioacetamide-induced liver fibrosis in rats through modulation of the PI3K/Akt pathway

AIMS

Naringin (NR) is a flavanone glycoside extracted from grapefruits and citrus fruits. The aim of this study is to investigate the antifibrotic efficacy of NR in thioacetamide (TAA)-induced hepatic fibrosis in rats through evaluating NR effect on the PI3K/Akt pathway.

MAIN METHODS

Hepatic fibrosis was induced in rats by intraperitoneal injection of TAA (200mg/kg) twice per week for 6weeks. Simultaneously, NR (40mg/kg/day, p.o.) was given along with TAA injection. The ratio of P-Akt/Akt was assessed in hepatic homogenate as well as antioxidant enzymes (catalase, superoxide dismutase (SOD), glutathione peroxidase (GPx)) and lipid peroxidation marker, malondialdehyde (MDA). Serum level of interleukin (IL)-6 were measured using ELISA. Hepatic tissues were examined histopathologically using hematoxylin and eosin (H&E) and Masson trichome staining. Tissue expression of alpha smooth muscle actin (α-SMA), transforming growth factor β1 (TGF-β1), caspase-3 and fibronectin were scored immunohistochemically. Finally, the mRNA level of cytokine genes (IL-1β, IL-6, IL-10, interferon gamma (IFN-γ)), caspase-3, TGF-β1 and fibronectin were quantified using qPCR.

KEY FINDINGS

NR significantly suppressed Akt phosphorylation associated with increased number of caspase-3 positive cells especially in the fibrotic areas. Liver tissues of treated rats showed restoration of normal liver histology and decrease in collagen and fibronectin deposition. Furthermore, NR treatment ameliorated oxidative stress and inflammatory cytokine production.

SIGNIFICANCE

NR alleviated experimental liver fibrosis through inhibition of PI3K/Akt pathway beside its anti-inflammatory and antioxidant effects. Therefore, NR is a promising therapeutic candidate for hepatic fibrosis.

1-Methyl-L-tryptophan promotes the apoptosis of hepatic stellate cells arrested by interferon-γ by increasing the expression of IFN-γRβ, IRF-1 and FAS

Liver fibrosis, a precursor to cirrhosis, is the result of the deposition of extracellular matrix (ECM) proteins and is mediated primarily by activated hepatic stellate cells (HSCs). In this study, we investigated the anti-fibrotic effects of interferon (IFN)-γ in activated HSCs in vitro and whether cell viability would be decreased by the inhibition of indoleamine 2,3-dioxygemase (IDO), which is responsible for cell cycle arrest. Following treatment with IFN-γ, cell signaling pathways and DNA content were analyzed to assess the inactivation of HSCs or the decrease in HSC proliferation. The IDO inhibitor, 1-methyl-L-tryptophan (1-MT), was used to determine whether IDO plays a key role in the regulation of activated HSCs, as IFN-γ increases the expression of IDO. IFN-γ significantly inhibited the growth of HSCs and downregulated the expression of α-smooth muscle actin (α-SMA) in the HSCs. IDO expression was markedly increased by IFN-γ through signal transducer and activator of transcription 1 (STAT1) activation and resulted in the depletion of tryptophan. This depletion induced G1 cell cycle arrest. When the cells were released from IFN-γ-mediated G1 cell cycle arrest by treatment with 1-MT, the apoptosis of the HSCs was markedly increased through the induction of IFN-γRβ, interferon regulatory factor (IRF-1) and FAS. Our results thus suggest that the inhibition of IDO enhances the suppression of activated HSCs, and therefore co-treatment with IFN-γ and 1-MT may be applied to ameliorate liver fibrosis.

Antifibrotics in chronic liver disease: tractable targets and translational challenges

Chronic liver disease prevalence is increasing globally. Iterative liver damage, secondary to any cause of liver injury, results in progressive fibrosis, disrupted hepatic architecture, and aberrant regeneration, which are defining characteristics of liver cirrhosis. Liver transplantation is an effective treatment for end-stage liver disease; however, demand greatly outweighs donor organ supply, and in many parts of the world liver transplantation is unavailable. Hence, effective antifibrotic therapies are urgently required. In the past decade, rapid progress has been made in our understanding of the pathophysiology of liver fibrosis and a large number of potential cellular and molecular antifibrotic targets have been identified. This has led to numerous clinical trials of antifibrotic agents in patients with chronic liver disease. However, none of these have resulted in a robust and reproducible effect on fibrosis. It is therefore imperative that the ongoing translational challenges are addressed, to convert scientific discoveries into potent antifibrotics and enable bridging of the translational gap between putative therapeutic targets and effective treatments for patients with chronic liver disease.

CUG-binding protein 1 regulates HSC activation and liver fibrogenesis. Nat Commun. 2016;7:13498. [PMID: 27853137 PMCID: PMC5118555 DOI: 10.1038/ncomms13498]

Excessive activation of hepatic stellate cells (HSCs) is a key step in liver fibrogenesis. Here we report that CUG-binding protein 1 (CUGBP1) expression is elevated in HSCs and positively correlates with liver fibrosis severity in human liver biopsies. Transforming growth factor-beta (TGF-β) selectively increases CUGBP1 expression in cultured HSCs in a p38 mitogen-activated protein kinase (MAPK)-dependent manner. Knockdown of CUGBP1 inhibits alpha smooth muscle actin (α-SMA) expression and promotes interferon gamma (IFN-γ) production in HSCs in vitro. We further show that CUGBP1 specifically binds to the 3′ untranslated region (UTR) of human IFN-γ mRNA and promotes its decay. In mice, knockdown of CUGBP1 alleviates, whereas its overexpression exacerbates, bile duct ligation (BDL)-induced hepatic fibrosis. Therefore, CUGBP1-mediated IFN-γ mRNA decay is a key event for profibrotic TGF-β-dependent activation of HSCs, and inhibiting CUGBP1 to promote IFN-γ signalling in activated HSCs could be a novel strategy to treat liver fibrosis.

Activation of hepatic stellate cells is a critical event in the development of fibrosis, which is driven by TGF-beta and inhibited by IFN-gamma. Here Wu et al. show that the RNA binding protein CUGBP1 is increased by TGF-beta signalling and promotes IFN-gamma mRNA degradation.

Emerging therapeutic targets for the treatment of hepatic fibrosis

Fibrosis represents a response to chronic injury, aimed at maintaining organ integrity. Hepatic fibrosis is mainly related to chronic viral hepatitis B or C (HBV or HCV), alcoholic and nonalcoholic steatohepatitis (NASH), and biliary diseases. A deep understanding of the cellular and molecular mechanisms underlying liver fibrosis has enabled the development of 'pathogenetic tailored' therapeutic interventions. However, effective drugs to prevent or revert hepatic fibrosis are still lacking. In this review, we discuss the cellular populations and the molecular pathways involved in liver fibrogenesis as well as the novel approaches currently being tested in clinical trials.

Immune-modulators to combat hepatitis B virus infection: From IFN-α to novel investigational immunotherapeutic strategies

Chronic hepatitis B virus (HBV) infection remains a major challenge for clinicians, as there are only two types of approved therapies: interferon-alpha (IFN-α) or its pegylated form, Peg-IFN-α and nucleoside analogs (e.g. tenofovir, entecavir...). The first are used as finite-duration treatments of around 48-52 weeks, while the second must be taken life-long to prevent rebound. Other immune-modulators, including other types of recombinant IFNs and cytokines/chemokines, could be developed for treating chronic hepatitis B. Alternatively, strategies aimed either at restoring or favoring the endogenous production of IFNs, cytokines and/or chemokines, or at alleviating HBV-mediated inhibitory processes could also be envisaged. In this article, we review current investigational, preclinical and clinical efforts to implement immune-modulatory components in the therapy of chronic hepatitis B. This review forms part of a symposium in Antiviral Research on "An unfinished story: from the discovery of the Australia antigen to the development of new curative therapies for hepatitis B".

Precision-cut kidney slices (PCKS) to study development of renal fibrosis and efficacy of drug targeting ex vivo

Renal fibrosis is a serious clinical problem resulting in the greatest need for renal replacement therapy. No adequate preventive or curative therapy is available that could be clinically used to target renal fibrosis specifically. The search for new efficacious treatment strategies is therefore warranted. Although in vitro models using homogeneous cell populations have contributed to the understanding of the pathogenetic mechanisms involved in renal fibrosis, these models poorly mimic the complex in vivo milieu. Therefore, we here evaluated a precision-cut kidney slice (PCKS) model as a new, multicellular ex vivo model to study the development of fibrosis and its prevention using anti-fibrotic compounds. Precision-cut slices (200-300 μm thickness) were prepared from healthy C57BL/6 mouse kidneys using a Krumdieck tissue slicer. To induce changes mimicking the fibrotic process, slices were incubated with TGFβ1 (5 ng/ml) for 48 h in the presence or absence of the anti-fibrotic cytokine IFNγ (1 µg/ml) or an IFNγ conjugate targeted to PDGFRβ (PPB-PEG-IFNγ). Following culture, tissue viability (ATP-content) and expression of α-SMA, fibronectin, collagen I and collagen III were determined using real-time PCR and immunohistochemistry. Slices remained viable up to 72 h of incubation, and no significant effects of TGFβ1 and IFNγ on viability were observed. TGFβ1 markedly increased α-SMA, fibronectin and collagen I mRNA and protein expression levels. IFNγ and PPB-PEG-IFNγ significantly reduced TGFβ1-induced fibronectin, collagen I and collagen III mRNA expression, which was confirmed by immunohistochemistry. The PKCS model is a novel tool to test the pathophysiology of fibrosis and to screen the efficacy of anti-fibrotic drugs ex vivo in a multicellular and pro-fibrotic milieu. A major advantage of the slice model is that it can be used not only for animal but also for (fibrotic) human kidney tissue.

Drug Discovery Collection: TGFβ induces renal fibrosis in ex vivo cultured precision-cut kidney slices, which can be attenuated by IFNγ.

Selective delivery of IFN-γ to renal interstitial myofibroblasts: a novel strategy for the treatment of renal fibrosis

Renal fibrosis leads to end-stage renal disease demanding renal replacement therapy because no adequate treatment exists. IFN-γ is an antifibrotic cytokine that may attenuate renal fibrosis. Systemically administered IFN-γ causes side effects that may be prevented by specific drug targeting. Interstitial myofibroblasts are the effector cells in renal fibrogenesis. Here, we tested the hypothesis that cell-specific delivery of IFN-γ to platelet-derived growth factor receptor β (PDGFRβ)-expressing myofibroblasts attenuates fibrosis in an obstructive nephropathy [unilateral ureteral obstruction (UUO)] mouse model. PEGylated IFN-γ conjugated to PDGFRβ-recognizing peptide [(PPB)-polyethylene glycol (PEG)-IFN-γ] was tested in vitro and in vivo for antifibrotic properties and compared with free IFN-γ. PDGFRβ expression was >3-fold increased (P < 0.05) in mouse fibrotic UUO kidneys and colocalized with α-smooth muscle actin-positive (SMA(+)) myofibroblasts. In vitro, PPB-PEG-IFN-γ significantly inhibited col1a1, col1a2, and α-SMA mRNA expression in TGF-β-activated NIH3T3 fibroblasts (P < 0.05). In vivo, PPB-PEG-IFN-γ specifically accumulated in PDGFRβ-positive myofibroblasts. PPB-PEG-IFN-γ treatment significantly reduced renal collagen I, fibronectin, and α-SMA mRNA and protein expression. Compared with vehicle treatment, PPB-PEG-IFN-γ preserved tubular morphology, reduced interstitial T-cell infiltration, and attenuated lymphangiogenesis (all P < 0.05) without affecting peritubular capillary density. PPB-PEG-IFN-γ reduced IFN-γ-related side effects as manifested by reduced major histocompatibility complex class II expression in brain tissue (P < 0.05 vs. free IFN-γ). Our findings demonstrate that specific targeting of IFN-γ to PDGFRβ-expressing myofibroblasts attenuates renal fibrosis and reduces systemic adverse effects.

Use of mesenchymal stem cells to treat liver fibrosis: Current situation and future prospects

Progressive liver fibrosis is a major health issue for which no effective treatment is available, leading to cirrhosis and orthotopic liver transplantation. However, organ shortage is a reality. Hence, there is an urgent need to find alternative therapeutic strategies. Cell-based therapy using mesenchymal stem cells (MSCs) may represent an attractive therapeutic option, based on their immunomodulatory properties, their potential to differentiate into hepatocytes, allowing the replacement of damaged hepatocytes, their potential to promote residual hepatocytes regeneration and their capacity to inhibit hepatic stellate cell activation or induce their apoptosis, particularly via paracrine mechanisms. The current review will highlight recent findings regarding the input of MSC-based therapy for the treatment of liver fibrosis, from in vitro studies to pre-clinical and clinical trials. Several studies have shown the ability of MSCs to reduce liver fibrosis and improve liver function. However, despite these promising results, some limitations need to be considered. Future prospects will also be discussed in this review.

Biomarkers of liver fibrosis

Liver fibrosis is the final common pathway for almost all causes of chronic liver injury. Liver fibrosis is now known to be a dynamic process having significant potential for resolution. Therefore, fibrosis prediction is an essential part of the assessment and management of patients with chronic liver disease. As such, there is strong demand for reliable liver biomarkers that provide insight into disease etiology, diagnosis, therapy, and prognosis in lieu of more invasive approaches such as liver biopsy. Current diagnostic strategies range from use of serum biomarkers to more advanced imaging techniques including transient elastography and magnetic resonance imaging. In addition to these modalities, there are other approaches including the use of novel, but yet to be validated, biomarkers. In this chapter, we discuss the biomarkers of liver fibrosis including the use of invasive and noninvasive biomarkers and disease-specific biomarkers in various chronic liver diseases.

IFN-γ deficiency attenuates hepatic inflammation and fibrosis in a steatohepatitis model induced by a methionine- and choline-deficient high-fat diet

Cytokines play important roles in all stages of steatohepatitis, including hepatocyte injury, the inflammatory response, and the altered function of sinusoidal cells. This study examined the involvement of a major inflammatory cytokine, interferon-γ (IFN-γ), in the progression of steatohepatitis. In a steatohepatitis model by feeding a methionine- and choline-deficient high-fat (MCDHF) diet to both wild-type and IFN-γ-deficient mice, the liver histology, expression of genes encoding inflammatory cytokines, and fibrosis-related markers were examined. To analyze the effects of IFN-γ on Kupffer cells in vitro, we examined the tumor necrosis factor-α (TNF-α) production by a mouse macrophage cell line. Forty two days of MCDHF diet resulted in weight loss, elevated aminotransferases, liver steatosis, and inflammation in wild-type mice. However, the IFN-γ-deficient mice exhibited less extensive changes. RT-PCR revealed that the expression of tumor necrosis factor-α (TNF-α), transforming growth factor-β, inducible nitric oxide synthase, interleukin-4 and osteopontin were increased in wild-type mice, although they were suppressed in IFN-γ-deficient mice. Seventy days of MCDHF diet induced much more liver fibrosis in wild-type mice than in IFN-γ-deficient mice. The expression levels of fibrosis-related genes, α-smooth muscle actin, type I collagen, tissue inhibitor of matrix metalloproteinase-1, and matrix metalloproteinase-2, were dramatically increased in wild-type mice, whereas they were significantly suppressed in IFN-γ-deficient mice. Moreover, in vitro experiments showed that, when RAW 264.7 macrophages were treated with IFN-γ, they produced TNF-α in a dose-dependent manner. The present study showed that IFN-γ deficiency might inhibit the inflammatory response of macrophages cells and subsequently suppress stellate cell activation and liver fibrosis. These findings highlight the critical role of IFN-γ in the progression of steatohepatitis.

IFN-γ inhibits liver progenitor cell proliferation in HBV-infected patients and in 3,5-diethoxycarbonyl-1,4-dihydrocollidine diet-fed mice

BACKGROUND & AIMS

Proliferation of liver progenitor cells (LPCs) is associated with inflammation and fibrosis in chronic liver diseases. However, how inflammation and fibrosis affect LPCs remains obscure.

METHODS

We examined the role of interferon (IFN)-γ, an important pro-inflammatory and anti-fibrotic cytokine, in LPC expansion in HBV-infected patients and in mice challenged with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)- or choline-deficient, ethionine-supplemented (CDE) diet as well as in primary LPCs and LPC cell line.

RESULTS

The CK19 staining scores correlated with inflammation and fibrosis grades in the livers from 110 HBV-infected patients. Nine-month IFN-γ treatment decreased LPC numbers, inflammation, and fibrosis in these HBV-infected patients. Similarly, a two-week IFN-γ treatment also decreased LPC activation in DDC-treated mice. Disruption of IFN-γ or its signaling components (e.g., IFNGR, STAT1, and IRF-1) increased LPC proliferation and liver fibrosis in DDC-fed mice. In contrast, deletion of IFN-γ did not increase, but rather slightly reduced LPC proliferation in CDE-fed mice. In vitro, IFN-γ attenuated proliferation of the LPC cell line BMOL and of primary LPCs from wild type mice, but not STAT1(-/-) or IRF-1(-/-) mice. Furthermore, co-culture assays suggest that IFN-γ can indirectly promote LPC proliferation via the activation of macrophages but attenuate it via the inhibition of hepatic stellate cells.

CONCLUSIONS

IFN-γ inhibits LPC expansion via the direct inhibition of LPC proliferation and indirect attenuation of liver fibrosis in the DDC model, but it may also enhance LPC expansion via the promotion of inflammation in the CDE model; thereby playing dual roles in regulating LPC proliferation in vivo.

The improving effects on hepatic fibrosis of interferon-γ liposomes targeted to hepatic stellate cells

No satisfactory anti-fibrotic therapies have yet been applied clinically. One of the main reasons is the inability to specifically target the responsible cells to produce an available drug concentration and the side-effects. Exploiting the key role of the activated hepatic stellate cells (HSCs) in both hepatic fibrogenesis and over-expression of platelet-derived growth factor receptor- (PDGFR- ), we constructed targeted sterically stable liposomes (SSLs) modified by a cyclic peptide (pPB) with affinity for the PDGFR- to deliver interferon (IFN)- to HSCs. The pPB-SSL-IFN- showed satisfactory size distribution. In vitro pPB-SSL could be taken up by activated HSCs. The study of tissue distribution via living-body animal imaging showed that the pPB-SSL-IFN- mostly accumulated in the liver until 24 h. Furthermore, the pPB-SSL-IFN- showed more significant remission of hepatic fibrosis. In vivo the histological Ishak stage, the semiquantitative score for collagen in fibrotic liver and the serum levels of collagen type IV-C in fibrotic rats treated with pPB-SSL-IFN- were less than those treated with SSL-IFN- , IFN- and the control group. In vitro pPB-SSL-IFN- was also more effective in suppressing activated HSC proliferation and inducing apoptosis of activated HSCs. Thus the data suggest that pPB-SSL-IFN- might be a more effective anti-fibrotic agent and a new opportunity for clinical therapy of hepatic fibrosis.

Effect of recombinant human growth hormone and interferon gamma on hepatic collagen synthesis and proliferation of hepatic stellate cells in cirrhotic rats

BACKGROUND

Fibrosis plays a key role in the development of liver cirrhosis. In this study, we investigated the effect of growth hormone and interferon gamma on hepatic collagen synthesis and the proliferation of hepatic stellate cells in a cirrhotic rat model.

METHODS

Cirrhosis was induced in rats using carbon tetrachloride. Rats were simultaneously treated with daily subcutaneous injections of recombinant human growth hormone or interferon gamma combined with recombinant human growth hormone. The control group was given saline. The relative content of type I and type IV collagen was assessed by indirect immunofluorescence analysis. Activated hepatic stellate cells were prepared from cirrhotic rats. The 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) method was used to assess the effects of recombinant human growth hormone and interferon gamma on these cells in vitro.

RESULTS

Both qualitative and quantitative analysis showed that type I and type IV collagen secretion increased with time after recombinant human growth hormone administration and was significantly higher than control and recombinant human growth hormone combined with interferon gamma administration. In vitro, recombinant human growth hormone significantly stimulated hepatic stellate cell proliferation in a concentration-dependent manner (10(-3)-10(-1) mg/100 μL), and interferon gamma (10(-2)-10(-1) μg/100 μL) significantly inhibited their growth compared to the control group. Interferon gamma combined with recombinant human growth hormone eliminated this growth-promoting effect to a certain degree in a concentration-dependent manner (10(-1) μg/100 μL, P<0.05, 10(-2)-10(-3) μg/100 μL, P>0.05) and a time-dependent manner (P<0.05).

CONCLUSIONS

Recombinant human growth hormone increased collagen secretion in cirrhotic rats in vivo and promoted the proliferation of hepatic stellate cells from cirrhotic rats in vitro. It is possible that concurrent interferon gamma therapy can offset these side-effects of recombinant human growth hormone.

Cytokines and STATs in Liver Fibrosis

Liver fibrosis, or cirrhosis, is a common end-stage condition of many chronic liver diseases after incomplete recovery from hepatocyte damage. During fibrosis progression, hepatocellular damage and inflammation trigger complex cellular events that result in collagen deposition and the disruption of the normal liver architecture. Hepatic stellate cell activation and transdifferentiation into myofibroblasts are key events in liver fibrogenesis. Research findings from cell culture and animal models have revealed that the Janus kinase-signal transducer and activator of transcription (Jak-STAT) signaling pathway, which can be activated by many cytokines, growth factors, and hormones, plays a critical role in hepatic fibrogenesis. This review summarizes the biological significance of diverse cytokines and their downstream signaling protein STATs in hepatic fibrogenesis.

Current status of novel antifibrotic therapies in patients with chronic liver disease

Fibrosis accumulation is a dynamic process resulting from a wound-healing response to acute or chronic liver injury of all causes. The cascade starts with hepatocyte necrosis and apoptosis, which instigate inflammatory signaling by chemokines and cytokines, recruitment of immune cell populations, and activation of fibrogenic cells, culminating in the deposition of extracellular matrix. These key elements, along with pathways of transcriptional and epigenetic regulation, represent fertile therapeutic targets. New therapies include drugs specifically designed as antifibrotics, as well as drugs already available with well-established safety profiles, whose mechanism of action may also be antifibrotic. At the same time, the development of noninvasive fibrogenic markers, and techniques (e.g. fibroscan), as well as combined scoring systems incorporating serum and clinical features will allow improved assessment of therapy response. In aggregate, the advances in the elucidation of the biology of fibrosis, combined with improved technologies for assessment will provide a comprehensive framework for design of antifibrotics and their analysis in well-designed clinical trials. These efforts may ultimately yield success in halting the progression of, or reversing, liver fibrosis.

Cortex Dictamni extract induces apoptosis of activated hepatic stellate cells via STAT1 and attenuates liver fibrosis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicines, Cortex Dictamni is prescribed for the treatment of a variety of inflammatory diseases such as acute rheumatoid arthritis, skin inflammation and jaundice.

AIM OF THE STUDY

This study was designed to investigate the effect of ethanol extract of Cortex Dictamni on treatment of hepatic fibrosis and its possible mechanisms.

MATERIALS AND METHODS

The in vivo effect of Cortex Dictamni extract (CDE) was evaluated by measuring histological changes and collagen content in CCl(4)-indcued hepatic fibrosis mice. Viability, apoptosis and protein expression of hepatic stellate cells (HSC) were analyzed by MTT, Annexin V staining and Western blot respectively.

RESULTS

CDE alleviated CCl(4)-induced hepatic fibrosis in mice and showed a much stronger inhibition of cell viability in activated HSC cell line HSC-T6 than that in normal hepatocyte L02 cells. Furthermore, CDE induced apoptosis of HSC-T6 cells associated with increased expressions of cleaved PARP and cleaved caspase-3. Interestingly, CDE activated STAT1 in HSC-T6 cells and the effect of CDE on apoptosis of HSC-T6 cells could be neutralized using JAK/STAT1 signaling inhibitor AG490.

CONCLUSIONS

These findings suggest that CDE possesses anti-fibrosis activity with selectively induction of activated HSC apoptosis via activating STAT1, which might be a novel strategy for hepatic fibrosis therapy.

Long-term antifibrotic action of interferon-γ treatment in patients with chronic hepatitis B virus infection

BACKGROUND

The first priority in treating fibrosis is to eliminate the causes that result in liver injury, e.g., hepatitis B and C virus. However, in many liver diseases the cause is either unknown or untreatable. The present study was designed to investigate the long-term antifibrotic effect of interferon-gamma (IFN-gamma) treatment in patients chronically infected with hepatitis B virus.

METHODS

A total of 42 patients, 30 treated with IFN-gamma and 12 controls, were enrolled from an original clinical trial (Clin Gastroenterol Hepatol 2005;3:819.). Three serial liver biopsies that were obtained at the initiation and end of IFN-gamma treatment as well as 4 to 6 years after treatment discontinuation were assessed according to the modified Chevallier scoring system.

RESULTS

Twenty-five out of 30 IFN-gamma-treated patients were followed up until 4 to 6 years after the treatment was stopped. However, all controls were excluded from follow-up due to death, loss and elevated virus level within 2 years. Twenty-five IFN-gamma-treated patients had stable serum liver function and liver fibrosis indices without any further anti-viral or anti-fibrotic treatment. Improved inflammatory and fibrotic scores were found after nine months of IFN-gamma treatment according to the modified Chevallier scoring system (inflammation: 11.8+/-6.5 at the beginning of IFN-gamma treatment vs. 9.2+/-4.1 after 9 months, P<0.05; fibrosis: 15.0+/-7.3 at baseline vs. 12.6+/-6.8 after 9 months, P<0.05). Among them, 14 patients accepted a third serial liver biopsy 4 to 6 years after treatment discontinuation, and the fibrotic score was increased (14.2+/-8.3 vs. 11.9+/-7.6 after 9 months, P<0.05).

CONCLUSIONS

Nine-month IFN-gamma treatment significantly improves the fibrosis score in patients with chronic HBV infection. The majority of patients demonstrate stable serum biochemical indices and quality of life. However, they do not show a long-term benefit according to histological criteria. Given the limited sample size, long-term IFN-gamma treatment regimens should be assessed in further clinical trials.

Suppression of innate immunity (natural killer cell/interferon-γ) in the advanced stages of liver fibrosis in mice

Activation of innate immunity (natural killer [NK] cell/interferon-γ [IFN-γ]) has been shown to play an important role in antiviral and antitumor defenses as well as antifibrogenesis. However, little is known about the regulation of innate immunity during chronic liver injury. Here, we compared the functions of NK cells in early and advanced liver fibrosis induced by a 2-week or a 10-week carbon tetrachloride (CCl(4) ) challenge, respectively. Injection of polyinosinic-polycytidylic acid (poly I:C) or IFN-γ induced NK cell activation and NK cell killing of hepatic stellate cells (HSCs) in the 2-week CCl(4) model. Such activation was diminished in the 10-week CCl(4) model. Consistent with these findings, the inhibitory effect of poly I:C and IFN-γ on liver fibrosis was markedly reduced in the 10-week versus the 2-week CCl(4) model. In vitro coculture experiments demonstrated that 4-day cultured (early activated) HSCs induce NK cell activation via an NK group 2 member D/retinoic acid-induced early gene 1-dependent mechanism. Such activation was reduced when cocultured with 8-day cultured (intermediately activated) HSCs due to the production of transforming growth factor-β (TGF-β) by HSCs. Moreover, early activated HSCs were sensitive, whereas intermediately activated HSCs were resistant to IFN-γ-mediated inhibition of cell proliferation, likely due to elevated expression of suppressor of cytokine signaling 1 (SOCS1). Disruption of the SOCS1 gene restored the IFN-γ inhibition of cell proliferation in intermediately activated HSCs. Production of retinol metabolites by HSCs contributed to SOCS1 induction and subsequently inhibited IFN-γ signaling and functioning, whereas production of TGF-β by HSCs inhibited NK cell function and cytotoxicity against HSCs.

CONCLUSION

The antifibrogenic effects of NK cell/IFN-γ are suppressed during advanced liver injury, which is likely due to increased production of TGF-β and expression of SOCS1 in intermediately activated HSCs.

HBV life cycle and novel drug targets

With up to 400 million affected people worldwide, chronic hepatitis B virus (HBV) infection is still a major health care problem. During the last decade, several novel therapeutic approaches have been developed and evaluated. In most regions of the world, interferon-α, and nucleos(t)ide analogues (NUCs) are currently approved. Despite major improvements, none of the existing therapies is optimal since viral clearance is rarely achieved. Recently, a better understanding of the HBV life cycle and the development of novel model systems of HBV infection have led to the development of novel antiviral strategies and drug targets. This review will focus on current and potential future drug targets in the HBV life cycle and strategies to modulate the virus-host interaction.

Inhibition of hepatitis B virus DNA replication by a thermostable interferon-γ variant

BACKGROUND

Treatment of HBV chronic carriers using interferon (IFN)-α or nucleoside/nucleotide analogues fails to suppress viral infection. Type-II IFN-γ has been shown to inhibit HBV replication. The goal of the present work was to evaluate the antiviral efficacy against HBV of a thermostable IFN-γ variant isolated using Massive Mutagenesis and thermoresistant selection (THR) technologies.

METHODS

The thermostability of wild-type (wt) and S63C IFN-γ was determined in vitro and in vivo. Activation of the IFN-γ responsive element by wt and S63C IFN-γ was tested using a luciferase assay. HepG2.2.15 cells constitutively expressing HBV were used to analyse the antiviral activity of wt and S63C IFN-γ against HBV replication. Intracellular HBV DNA was detected by Southern blot and quantified by real-time PCR analyses.

RESULTS

S63C IFN-γ was shown to be more thermostable and had a longer half-life than wt IFN-γ. Both wt and S63C IFN-γ displayed a similar capacity to activate the IFN pathway. The treatment of HepG2.2.15 cells with wt or S63C IFN-γ induced the inhibition of HBV viral replication. After heating, S63C IFN-γ displayed better conservation of its antiviral activity against HBV when compared with wt IFN-γ.

CONCLUSIONS

These results confirm that the THR method can be used to isolate mutants with enhanced thermostability and demonstrate that a thermostable IFN-γ variant presents antiviral properties against HBV replication. This molecule could provide a new strategy to treat patients who do not respond to antiviral therapy.

Smad7 dependent expression signature highlights BMP2 and HK2 signaling in HSC transdifferentiation

AIM: To analyse the influence of Smad7, antagonist of transforming growth factor (TGF)-β canonical signaling pathways on hepatic stellate cell (HSC) transdifferentiation in detail.

METHODS: We systematically analysed genes regulated by TGF-β/Smad7 in activated HSCs by microarray analysis and validated the results using real time polymerase chain reaction and Western blotting analysis.

RESULTS: We identified 100 known and unknown targets underlying the regulation of Smad7 expression and delineated 8 gene ontology groups. Hk2, involved in glycolysis, was one of the most downregulated proteins, while BMP2, activator of the Smad1/5/8 pathway, was extremely upregulated by Smad7. However, BMP2 dependent Smad1 activation could be inhibited in vitro by Smad7 overexpression in HSCs.

CONCLUSION: We conclude (1) the existence of a tight crosstalk of TGF-β and BMP2 pathways in HSCs and (2) a Smad7 dependently decreased sugar metabolism ameliorates HSC activation probably by energy withdrawal.

Prevention of liver fibrosis by triple helix-forming oligodeoxyribonucleotides targeted to the promoter region of type I collagen gene

Hepatic fibrosis leading to cirrhosis remains a global health problem. The most common etiologies are alcoholism and viral infections. Liver fibrosis is associated with major changes in both quantity and composition of extracellular matix and leads to disorganization of the liver architecture and irreversible damage to the liver function. As of now there is no effective therapy to control fibrosis. The end product of fibrosis is abnormal synthesis and accumulation of type I collagen in the extracellular matrix, which is produced by activated stellate or Ito cells in the damaged liver. Therefore, inhibition of transcription of type I collagen should in principle inhibit its production and accumulation in liver. Normally, DNA exists in a duplex form. However, under some circumstances, DNA can assume triple helical (triplex) structures. Intermolecular triplexes, formed by the addition of a sequence-specific third strand to the major groove of the duplex DNA, have the potential to serve as selective gene regulators. Earlier, we demonstrated efficient triplex formation between the exogenously added triplex-forming oligodeoxyribonucleotides (TFOs) and a specific sequence in the promoter region of the COL1A1 gene. In this study we used a rat model of liver fibrosis, induced by dimethylnitrosamine, to test whether these TFOs prevent liver fibrosis. Our results indicate that both the 25-mer and 18-mer TFOs, specific for the upstream nucleotide sequence from -141 to -165 (relative to the transcription start site) in the 5' end of collagen gene promoter, effectively prevented accumulation of liver collagen and fibrosis. We also observed improvement in liver function tests. However, mutations in the TFO that eliminated formation of triplexes are ineffective in preventing fibrosis. We believe that these TFOs can be used as potential antifibrotic therapeutic molecules.

Antifibrotic therapies: will we ever get there?

Progressive hepatic fibrosis is the final common pathway for most chronic liver injuries, leading to cirrhosis with risk of liver failure and hepatocellular carcinoma. It is now recognized that fibrosis is a dynamic process, and may be reversible prior to the establishment of advanced architectural changes to the liver. The most effective antifibrotic strategy is to cure the underlying disease process before advanced fibrosis has developed. Unfortunately, this is often not possible, and specific antifibrotic therapies are needed. Advances in the understanding of the pathogenesis of liver fibrosis have identified several potential novel therapeutic targets, but unfortunately clinical development has been disappointing. One major limitation has been the often prolonged natural history of fibrosis compared to experimental models, and difficulties in accurate noninvasive fibrosis assessment, thus making clinical trial design difficult. In this review, we highlight the most promising current antifibrotic strategies.

Experience of a single center with congenital hepatic fibrosis: A review of the literature

Congenital hepatic fibrosis (CHF) is an autosomal recessive inherited malformation defined pathologically by a variable degree of periportal fibrosis and irregularly shaped proliferating bile ducts. It is one of the fibropolycystic diseases, which also include Caroli disease, autosomal dominant polycystic kidney disease, and autosomal recessive polycystic kidney disease. Clinically it is characterized by hepatic fibrosis, portal hypertension, and renal cystic disease. CHF is known to occur in association with a range of both inherited and non-inherited disorders, with multiorgan involvement, as a result of ductal plate malformation. Because of the similarities in the clinical picture, it is necessary to differentiate CHF from idiopathic portal hypertension and early liver cirrhosis, for which a liver biopsy is essential. Radiological tests are important for recognizing involvement of other organ systems. With regards to our experience at Hacettepe University, a total of 26 patients have been diagnosed and followed-up between 1974 and 2009 with a diagnosis of CHF. Presentation with Caroli syndrome was the most common diagnosis, with all such patients presenting with symptoms of recurrent cholangitis and symptoms related to portal hypertension. Although portal fibrosis is known to contribute to the ensuing portal hypertension, it is our belief that portal vein cavernous transformation also plays an important role in its pathogenesis. In all patients with CHF portal vein morphology should be evaluated by all means since portal vein involvement results in more severe and complicated portal hypertension. Other associations include the Joubert and Bardet-Biedl syndromes.

Antifibrotics for chronic hepatitis C

Development and testing of antifibrotic agents for the treatment of chronic hepatitis C have generally been targeted toward hepatic stellate cells, transforming growth factor-beta, the inflammatory response, or extracellular matrix accumulation. Although several agents such as interferon-gamma, long-term pegylated interferon, and caspase inhibitors have been studied, none have proved to be effective to date. There is a clear need for drugs that inhibit or reverse hepatic fibrosis as these would be immediately applicable to patients for whom antiviral therapy has failed or who have contraindications to antiviral therapy such as those with decompensated liver disease or renal failure. A major impediment in the development of new drugs in this field has been the inability to identify appropriate histologic or clinical end points within a reasonable period of study. Progress on providing suitable end points to therapy will then promote the development of newer agents.

Th1-type epitopes-based cocktail PDDV attenuates hepatic fibrosis in C57BL/6 mice with chronic Schistosoma japonicum infection

Schistosomiasis is one of the world's major public health problems in terms of morbidity and mortality, which is characterized by a marked egg-induced CD4(+) T-cell programmed granulomatous inflammation and cumulative fibrosis. Here PDDV (peptide-DNA dual vaccine), a widely used non-viral gene delivery system, was applied. The cocktail PDDV, based on four Th1-type epitope peptides identified from Schistosoma japonicum vaccine candidates and CpG ODN1826, could induce dominant Th1-type response in C57BL/6J mice (P<0.05). The histopathological staging and collagen assessment for fibrosis showed that the cocktail PDDV presented an obvious down-regulation effect on hepatic fibrosis caused by chronic S. japonicum infection (P<0.05), and IFN-gamma, IL-4 and IL-13 mRNAs in liver detected by RT-PCR also showed that the cocktail PDDV represented the ability to up-regulate Th1-type responses, which paralleled with a decrease expression of alpha-SMA (P<0.05) and the up-regulated MMP9/TIMP1 balance (P<0.05) when compared to the control groups. Therefore, it is indicated that the cocktail PDDV can significantly attenuate hepatic fibrosis, in parallel with the decreased HSCs activation and the up-regulated MMP9/TIMP1 balance in favor of matrix degradation, which may be partially dependent on the increased Th1 response to restore the Th1/Th2 balance.

Assay of serum IL-27 and its significance in HBV-infected patients

AIM: To investigate the change and clinical significance of serum chemokine IL-27 in HBV-infected patients.

METHODS: The serum concentration of IL-27 was detected by enzyme linked immunosorbent assay (ELISA); HBV DNA was detected by fluorescent quantitive polymerase chain reaction (FQ-PCR); liver function was assayed by automatic biochemistry analyzer.

RESULTS: Serum concentrations of IL-27 in control group (n = 41), acute hepatitis B group (n = 33), mild chronic hepatitis B (CHB) group (n = 32), moderate CHB group (n = 30) and severe CHB group (n = 32) were 14.123 ± 15.627 ng/L, 56.880 ± 15.813 ng/L, 23.872 ± 22.801 ng/L, 29.849 ± 24.300 ng/L, 35.703 ± 18.575 ng/L, respectively. The concentration of IL-27 was significantly higher in all HB groups than in control group (P < 0.05 or 0.01). The concentration of IL27 was significantly higher in severe CHB group than in mild CHB group (P < 0.05). However, the disparity of IL-27 concentration between mild CHB and moderate CHB group was statistically significant.

CONCLUSION: It is possible that IL-27 promotes immune clearance in acute hepatitis, however, in chronic hepatitis B it may have some cytopathic effect (CPE).

Prevention and treatment of hepatic cirrhosis with herbal medicine Hongtian Gankang

AIM: To investigate the mechanism underlying preventing and treating hepatic cirrhosis with Hong Tian Gan Kang (HTGK) in mice.

METHODS: Sixty mice were divided randomly into 4 groups: normal control group, model control group, prevention group and treatment group. Except the mice in normal control group, all mice were given injection of CCl₄ into abdominal cavity that had been proved to induce experimental hepatic cirrhosis. In prevention group, mice were also given HTGK simultaneously by intragastric administration for 180 days, whereas mice in treatment group were given HTGK 150 days after modeling. Liver tissue and spleen tissue were made into sections stained with HE to evaluate the extent of liver cirrhosis and morphologic changes and to detect the expression of TGF-β1, IFN-γ, IgG, CD3 using immunohistochemistry.

RESULTS: Expression level of TGF-β1 in liver and spleen was markedly higher in model group than in control, prevention and treatment groups (F = 80.155, 120.850, both P < 0.05). The expression of IFN-γ and IgG was most obvious in treatment group, second in prevention group and least in model group (F = 53.584, 118.240, 85.075, 105.566, all P < 0.05). Compared with model group, expression levels of CD3 in prevention and treatment groups were significantly increased (F = 42.969, 69.775, both P < 0.05).

CONCLUSION: HTGK can improve the function of immune system so that it can prevent and cure hepatic cirrhosis effectively.

Interferons and their use in persistent viral infections

In 2007, the world celebrated the 50th anniversary of the discovery of interferon (IFN) by Isaacs and Lindenmann. Subsequently, the IFN-alpha gene was cloned, fully sequenced and IFN-alpha was produced in recombinant form. Recombinant IFN-alpha is now used as the basis for treatment of chronic hepatitis C virus infection and can also be used to treat certain forms of chronic hepatitis B virus infections. IFNs have also been used in other viral infections, although with less success. The antiviral mechanisms of IFNs are reviewed in this chapter as well as the utility of IFNs in the treatment of persistent viral infections.

Advances in antifibrotic therapy

Sustained progress in defining the molecular pathophysiology of hepatic fibrosis has led to a comprehensive framework for developing antifibrotic therapies. Indeed, the single greatest limitation in bringing new drugs to the clinical setting is a lack of clarity regarding clinical trial and treatment end points, not a lack of promising agents. A range of treatments, including those developed for other indications, as well as those specifically developed for hepatic fibrosis, are nearing or in clinical trials. Most are focused on attacking features of either hepatic injury and/or activated stellate cells and myofibroblasts, which are the primary sources of extracellular matrix (scar) proteins. Thus, features of injury and stellate cell activation provide a useful template for classifying these emerging agents and point to a new class of therapies for patients with fibrosing liver disease.

Systematic review: hepatic fibrosis - regression with therapy

BACKGROUND

Hepatic fibrosis occurs in response to chronic liver injury, regardless of the cause. An impressive amount of knowledge concerning the pathogenesis and treatment of liver fibrosis has emerged over the past few years. The hallmark of this event is the activation of the hepatic stellate cell. The latter event causes accumulation of extracellular matrix and formation of scar, leading to deterioration in hepatic function.

AIM

To assess chronic liver injury, many invasive and non-invasive methods have been suggested.

METHODS

Although transient elastography, image analysis of fractal geometry and fibrotest with actitest have been used in clinical practice, liver biopsy remains the recommended choice, especially when histological staging of fibrosis or response to treatment is needed.

CONCLUSIONS

The recent advances in anti-viral therapy have resulted in many reports on fibrosis and even on cirrhosis regression, especially early and in young people. A number of new agents have been suggested for the treatment of fibrosis, with promising results in animals; however, their efficacy in humans remains to be elucidated. The investigation of heterogeneity and plasticity of hepatic stellate cells is a topic of scientific interest and may result in improvements in patient management.