Interferon alfa and gamma inhibit proliferation and collagen synthesis of human Ito cells in culture

Mouse Type-I Interferon-Mannosylated Albumin Fusion Protein for the Treatment of Chronic Hepatitis

Although a lot of effort has been put into creating drugs and combination therapies against chronic hepatitis, no effective treatment has been established. Type-I interferon is a promising therapeutic for chronic hepatitis due to its excellent anti-inflammatory effects through interferon receptors on hepatic macrophages. To develop a type-I IFN equipped with the ability to target hepatic macrophages through the macrophage mannose receptor, the present study designed a mouse type-I interferon-mannosylated albumin fusion protein using site-specific mutagenesis and albumin fusion technology. This fusion protein exhibited the induction of anti-inflammatory molecules, such as IL-10, IL-1Ra, and PD-1, in RAW264.7 cells, or hepatoprotective effects on carbon tetrachloride-induced chronic hepatitis mice. As expected, such biological and hepatoprotective actions were significantly superior to those of human fusion proteins. Furthermore, the repeated administration of mouse fusion protein to carbon tetrachloride-induced chronic hepatitis mice clearly suppressed the area of liver fibrosis and hepatic hydroxyproline contents, not only with a reduction in the levels of inflammatory cytokine (TNF-α) and fibrosis-related genes (TGF-β, Fibronectin, Snail, and Collagen 1α2), but also with a shift in the hepatic macrophage phenotype from inflammatory to anti-inflammatory. Therefore, type-I interferon-mannosylated albumin fusion protein has the potential as a new therapeutic agent for chronic hepatitis.

Interferon-Gamma Increases the Immune Modulation of Umbilical Cord-Derived Mesenchymal Stem Cells but Decreases Their Chondrogenic Potential

INTRODUCTION

The pro-inflammatory cytokine interferon-gamma (IFN-γ) is reported to be an agent that boosts the immune modulation of mesenchymal stem cells (MSCs). However, the effects of IFN-γ on the chondrogenic potential of treated MSCs have not been evaluated in depth. This study aimed to evaluate the effects of IFN-γ on the immune modulation and chondrogenic potential of human umbilical cord-derived MSCs (hUC-MSCs).

METHODS

UC-MSCs were isolated and expanded following published protocols. They were characterized as MSCs before their use in further experiments. The UC-MSCs were treated with IFN-γ at 10 ng/mL for 48 h. Changes in phenotype were investigated based on changes in MSC markers, immunomodulatory genes (TGF-β, IL-4, and IDO) for immune modulation, and cartilage-related genes during the induction of differentiation (Col1a2, Col2a1, Sox9, Runx2, and Acan) for chondrogenic potential.

RESULTS

IFN-γ-treated UC-MSCs maintained MSC markers and exhibited decreased expression of transcriptional regulatory factors in chondrogenesis (Sox9 and Runx2) and the extracellular matrix-specific genes Col1a2 and Acan but not Col2a1 compared to non-treated cells (p < 0.05). Furthermore, the immunomodulatory capability of IFN-γ-treated UC-MSCs was clearly revealed through their increased expression of IDO and IL-4 and decreased expression of TGF-β compared to non-treated cells (p < 0.05).

CONCLUSION

This study demonstrated that UC-MSCs treated with IFN-γ at 10 ng/mL had reduced expression of chondrocyte-specific genes; however, they maintained multi-lineage differentiation and exhibited immunomodulatory properties.

The chemoprotective effects of IFN-α-2b on rat hepatocarcinogenesis are blocked by vitamin E supplementation

Many cancer patients receive their classical therapies together with vitamin supplements. However, the effectiveness of these strategies is on debate. Here we aimed to evaluate how vitamin E supplementation affects the anticancer effects of interferon (IFN-α) using an early-model of liver cancer development (initiation-promotion, IP). Male Wistar rats subjected to this model were divided as follows: untreated (IP), IP treated with recombinant IFN-α-2b (6.5  ×  105 U/kg), IP treated with vitamin E (50 mg/kg), and IP treated with combination of vitamin E and IFN-α-2b. After treatments rats were fasted and euthanized and plasma and livers were collected. Combined administration of vitamin E and IFN-α-2b induced body weight drop, increased liver apoptosis, and low levels of hepatic lipids. Interestingly, vitamin E and IFN-α-2b combination also induced an increase in altered hepatic foci number, but not in size. It seems that vitamin E acts on its antioxidant capability in order to block the oxidative stress induced by IFN-α-2b, blocking in turn its beneficial effects on preneoplastic livers, leading to harmful final effects. In conclusion, this study shows that vitamin E supplementation in IFN-α-2b-treated rats exerts unwanted effects; and highlights that in spite of being natural, nutritional supplements may not always exert beneficial outcomes when used as complementary therapy for the treatment of cancer.

Hepatic stellate cell as a Mac-2-binding protein-producing cell in patients with liver fibrosis

BACKGROUND

Mac-2 binding protein (M2BP) glycosylated isomer (M2BPGi) is a serum marker of liver fibrosis; M2BPGi is a glycosylated form of M2BP. Hepatocytes and hepatic stellate cells (HSCs) have been studied to determine the source of M2BP. This study proposes to identify the origin of M2BP in fibrotic liver.

METHODS

Using liver fibrosis tissue specimens from 15 patients with liver cancer, M2BP mRNA and M2BP were detected by in situ hybridization and immunohistochemistry, respectively. The expression levels of M2BP mRNA were evaluated with scores of 3, 2, and 1. Fluorescent in situ hybridization was carried out to evaluate the distribution of M2BP mRNA and the activated-HSC marker αSMA mRNA; multicolor fluorescent immunohistochemistry was used for protein localization of M2BP, αSMA, and CD68. The Kruskal-Wallis test analyzed the relationship between M2BP mRNA expression and existing serum fibrosis markers.

RESULTS

M2BP mRNA was expressed in spindle-shaped cells along the fibrous septa and in the perisinusoidal area of the fibrotic liver. The HSC markers αSMA mRNA and M2BP mRNA were colocalized in the spindle-shaped cells; on the protein level, M2BP was expressed in Kupffer cells. M2BP mRNA expression was positively correlated with serum M2BPGi levels. Aspartate transaminase-to-platelet ratio index, Fibrosis-4, hyaluronic acid, and the 15-minute indocyanine green retention rate were significantly correlated with M2BP mRNA expression.

CONCLUSIONS

M2BP mRNA transcription in fibrotic liver was primarily observed in HSCs but not at the M2BP level, which suggests that HSCs might produce and introduce M2BP to Kupffer cells and serum.

Incorporating mucosal-associated invariant T cells into the pathogenesis of chronic liver disease

Mucosal-associated invariant T (MAIT) cells have been described in liver and non-liver diseases, and they have been ascribed antimicrobial, immune regulatory, protective, and pathogenic roles. The goals of this review are to describe their biological properties, indicate their involvement in chronic liver disease, and encourage investigations that clarify their actions and therapeutic implications. English abstracts were identified in PubMed by multiple search terms, and bibliographies were developed. MAIT cells are activated by restricted non-peptides of limited diversity and by multiple inflammatory cytokines. Diverse pro-inflammatory, anti-inflammatory, and immune regulatory cytokines are released; infected cells are eliminated; and memory cells emerge. Circulating MAIT cells are hyper-activated, immune exhausted, dysfunctional, and depleted in chronic liver disease. This phenotype lacks disease-specificity, and it does not predict the biological effects. MAIT cells have presumed protective actions in chronic viral hepatitis, alcoholic hepatitis, non-alcoholic fatty liver disease, primary sclerosing cholangitis, and decompensated cirrhosis. They have pathogenic and pro-fibrotic actions in autoimmune hepatitis and mixed actions in primary biliary cholangitis. Local factors in the hepatic microenvironment (cytokines, bile acids, gut-derived bacterial antigens, and metabolic by-products) may modulate their response in individual diseases. Investigational manipulations of function are warranted to establish an association with disease severity and outcome. In conclusion, MAIT cells constitute a disease-nonspecific, immune response to chronic liver inflammation and infection. Their pathological role has been deduced from their deficiencies during active liver disease, and future investigations must clarify this role, link it to outcome, and explore therapeutic interventions.

Intraperitoneal injection of IFN-γ restores microglial autophagy, promotes amyloid-β clearance and improves cognition in APP/PS1 mice

Autophagy is a major self-degradative process that maintains cellular homeostasis and function in mammalian cells. Autophagic dysfunction occurs in the early pathogenesis of Alzheimer’s disease (AD) and directly regulates amyloid-β (Aβ) metabolism. Although it has been proven that the cytokine IFN-γ enhances autophagy in macrophage cell lines, whether the signaling cascade is implicated in Aβ degradation in AD mouse models remains to be elucidated. Here, we found that 9 days of the intraperitoneal administration of IFN-γ significantly increased the LC3II/I ratio and decreased the level of p62 in APP/PS1 mice, an AD mouse model. In vitro, IFN-γ protected BV2 cells from Aβ toxicity by upregulating the expressions of Atg7 and Atg5 and the LC3II/I ratio, whereas these protective effects were ablated by interference with Atg5 expression. Moreover, IFN-γ enhanced autophagic flux, probably through suppressing the AKT/mTOR pathway both in vivo and in vitro. Importantly, using intravital two-photon microscopy and fluorescence staining, we found that microglia interacted with exogenous IFN-γ and Aβ, and surrounded Aβ in APP/PS1;CX3CR1-GFP^+/− mice. In addition, IFN-γ treatment decreased the Aβ plaque load in the cortex and hippocampus and rescued cognitive deficits in APP/PS1 mice. Our data suggest a possible mechanism by which the peripheral injection of IFN-γ restores microglial autophagy to induce the phagocytosis of cerebral Aβ, which represents a potential therapeutic approach for the use of exogenous IFN-γ in AD.

Co-administration of silymarin elevates the therapeutic effect of praziquantel through modulation of specific antibody profiles, Th1/Th2/Tregs cytokines and down-regulation of fibrogenesis in mice with Mesocestoides vogae (Cestoda) infection

Silymarin (SIL) represents a natural mixture of polyphenols showing an array of health benefits. The present study, carried out on a model cestode infection induced by Mesocestoides vogae tetrathyridia in the ICR strain of mice, was aimed at investigating the impact of SIL as adjunct therapy on the activity of praziquantel (PZQ) in relation to parasite burden, immunity and liver fibrosis within 20 days post-therapy. In comparison with PZQ alone, co-administration of SIL and PZQ stimulated production of total IgG antibodies to somatic and excretory-secretory antigens of metacestodes and modified the expression patterns of immunogenic molecules in both antigenic preparations. The combined therapy resulted in the elevation of IFN-γ and a decline of TNF-α and TGF-β1 in serum as compared to untreated group; however, SIL attenuated significantly the effect of PZQ on IL-4 and stimulated PZQ-suppressed phagocytosis of peritoneal macrophages. In the liver, SIL boosted the effect of PZQ on gene expression of the same cytokines in a similar way as was found in serum, except for down-regulation of PZQ-stimulated TNF-α. Compared to PZQ therapy, the infiltration of mast cells into liver after SIL co-administration was nearly abolished and correlated with suppressed activities of genes for collagen I, collagen III and α-SMA. In conclusion, co-administration of SIL modified the effects of PZQ therapy on antigenic stimulation of the immune system and modulated Th1/Th2/Tregs cytokines. In liver this was accompanied by reduced fibrosis, which correlated with significantly higher reduction of total numbers of tetrathyridia after combined therapy as compared with PZQ treatment.

Histological and biochemical evaluation of transforming growth factor-β activation and its clinical significance in patients with chronic liver disease

Transforming growth factor-β (TGF-β) is a key driver for liver fibrogenesis. TGF-β must be activated in order to function. Plasma kallikrein (PLK) is a TGF-β activator that cleaves the latency-associated protein (LAP) between arginine⁵⁸ and lysine⁵⁹ residues and releases active TGF-β from the latent TGF-β-LAP complex. Thus, the generation of two LAP degradation products, ending at arginine⁵⁸ (R⁵⁸/LAP-DPs) and beginning from lysine⁵⁹ (L⁵⁹/LAP-DPs), reflects PLK-dependent TGF-β activation. However, the significance and details of TGF-β activation in patients with chronic liver disease (CLD) remain uncertain. We herein examined the PLK-dependent TGF-β activation in patients by detecting R⁵⁸ and L⁵⁹/LAP-DPs. A total of 234 patients with CLD were included in this study. Liver biopsy specimens were used for immunostaining to detect R⁵⁸/LAP-DPs, while plasma samples were subjected to an enzyme-linked immunosorbent assay to measure the L⁵⁹/LAP-DP concentration. R⁵⁸/LAP-DP was robustly expressed in and around the sinusoidal cells before the development of the fibrous regions. The R⁵⁸/LAP-DP expression at fibrosis stage 1 was higher than at any other stages, and the relationship between the plasma L⁵⁹/LAP-DP level and the stage of fibrosis also showed a similar trend. The abundance of plasma L⁵⁹/LAP-DP showed no correlation with the levels of direct serum biomarkers of liver fibrosis; however, its changes during interferon-based therapy for chronic hepatitis C were significantly associated with virological responses. Our results suggest that PLK-dependent TGF-β activation occurs in the early stages of fibrosis and that its unique surrogate markers, R⁵⁸ and L⁵⁹/LAP-DPs, are useful for monitoring the clinical course of CLD.

Host Regulators of Liver Fibrosis During Human Schistosomiasis

Liver fibrosis is a wound-healing process purposely aimed at restoring organ integrity after severe injury caused by autoimmune reactions, mechanical stress or infections. The uncontrolled solicitation of this process is pathogenic and a pathognomonic feature of diseases like hepatosplenic schistosomiasis where exacerbated liver fibrosis is centrally positioned among the drivers of the disease morbidity and mortality. Intriguingly, however, liver fibrosis occurs and progresses dissimilarly in schistosomiasis-diseased individuals with the same egg burden and biosocial features including age, duration of residence in the endemic site and gender. This suggests that parasite-independent and currently poorly defined host intrinsic factors might play a defining role in the regulation of liver fibrosis, the hallmark of morbidity, during schistosomiasis. In this review, we therefore provide a comprehensive overview of all known host candidate regulators of liver fibrosis reported in the context of human schistosomiasis.

Hepatic fibrosis: It is time to go with hepatic stellate cell-specific therapeutic targets

Hepatic fibrosis is a pathological lesion, characterized by the progressive accumulation of extracellular matrix (ECM) in the perisinusoidal space and it is a major problem in chronic liver diseases. Phenotypic activation of hepatic stellate cells (HSC) plays a central role in the progression of hepatic fibrosis. Retardation of proliferation and clearance of activated HSCs from the injured liver is an appropriate therapeutic strategy for the resolution and treatment of hepatic fibrosis. Clearance of activated HSCs from the injured liver by autophagy inhibitors, proapoptotic agents and senescence inducers with the high affinity toward the activated HSCs may be the novel therapeutic strategy for the treatment of hepatic fibrosis in the near future.

Low IL-6, IL-10, and TNF-α and High IL-13 Cytokine Levels Are Associated with Severe Hepatic Fibrosis in Schistosoma mansoni Chronically Exposed Individuals

Several studies have attributed the etiopathogenesis of chronic Schistosoma mansoni related hepatic fibrosis to unregulated immune responses against trapped parasite ova in the host. However, there is limited data on immune profiles associated with varying degrees of the disease in a population under chronic exposure to the parasite. We therefore investigated the role of selected T-helper (Th)1, Th2, and Th17 cytokines in relation to hepatic fibrosis severity among individuals resident in a hyper-Schistosoma mansoni endemic region of Western Zambia. Two hundred and forty-four S. mansoni infected individuals with and without fibrosis were analysed for cytokine profiles. Based on hepatic fibrosis stage as determined by ultrasound, participants were categorized into Group 0, Group I, Group II, and Group III. Cytokines were measured in S. mansoni egg stimulated whole blood culture supernatants using the BD Cytometric Bead Array kits. Compared to the nonfibrotic group, participants in the severe hepatic fibrotic group produced less interleukin- (IL-) 6, IL-10, and tumour necrosis factor-alpha (TNF-α). On the other hand, IL-13 was significantly elevated in this group compared to the nonfibrotic group (p < 0.001). Our results suggest that low IL-6, IL-10, and TNF-α and high IL-13 levels may influence S. mansoni disease progression.

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.

The stellate cell system (vitamin A-storing cell system)

Past, present, and future research into hepatic stellate cells (HSCs, also called vitamin A-storing cells, lipocytes, interstitial cells, fat-storing cells, or Ito cells) are summarized and discussed in this review. Kupffer discovered black-stained cells in the liver using the gold chloride method and named them stellate cells (Sternzellen in German) in 1876. Wake rediscovered the cells in 1971 using the same gold chloride method and various modern histological techniques including electron microscopy. Between their discovery and rediscovery, HSCs disappeared from the research history. Their identification, the establishment of cell isolation and culture methods, and the development of cellular and molecular biological techniques promoted HSC research after their rediscovery. In mammals, HSCs exist in the space between liver parenchymal cells (PCs) or hepatocytes and liver sinusoidal endothelial cells (LSECs) of the hepatic lobule, and store 50-80% of all vitamin A in the body as retinyl ester in lipid droplets in the cytoplasm. SCs also exist in extrahepatic organs such as pancreas, lung, and kidney. Hepatic (HSCs) and extrahepatic stellate cells (EHSCs) form the stellate cell (SC) system or SC family; the main storage site of vitamin A in the body is HSCs in the liver. In pathological conditions such as liver fibrosis, HSCs lose vitamin A, and synthesize a large amount of extracellular matrix (ECM) components including collagen, proteoglycan, glycosaminoglycan, and adhesive glycoproteins. The morphology of these cells also changes from the star-shaped HSCs to that of fibroblasts or myofibroblasts.

Innate Lymphoid Cells: A Promising New Regulator in Fibrotic Diseases

Fibrosis is a consequence of chronic inflammation and the persistent accumulation of extracellular matrix, for which the cycle of tissue injury and repair becomes a predominant feature. Both the innate and adaptive immune systems play key roles in the progress of fibrosis. The recently identified subsets of innate lymphoid cells (ILCs), which are mainly localize to epithelial surfaces, have been characterized as regulators of chronic inflammation and tissue remodeling, representing a functional bridge between the innate and adaptive immunity. Moreover, recent research has implicated ILCs as potential contributing factors to several kinds of fibrosis diseases, such as hepatic fibrosis and pulmonary fibrosis. Here, we will summarize and discuss the key roles of ILCs and their related factors in fibrotic diseases and their potential for translation to the clinic.

Pharmacological Intervention in Hepatic Stellate Cell Activation and Hepatic Fibrosis

The activation and transdifferentiation of hepatic stellate cells (HSCs) into contractile, matrix-producing myofibroblasts (MFBs) are central events in hepatic fibrogenesis. These processes are driven by autocrine- and paracrine-acting soluble factors (i.e., cytokines and chemokines). Proof-of-concept studies of the last decades have shown that both the deactivation and removal of hepatic MFBs as well as antagonizing profibrogenic factors are in principle suitable to attenuate ongoing hepatic fibrosis. Although several drugs show potent antifibrotic activities in experimental models of hepatic fibrosis, there is presently no effective pharmaceutical intervention specifically approved for the treatment of liver fibrosis. Pharmaceutical interventions are generally hampered by insufficient supply of drugs to the diseased liver tissue and/or by adverse effects as a result of affecting non-target cells. Therefore, targeted delivery systems that bind specifically to receptors solely expressed on activated HSCs or transdifferentiated MFBs and delivery systems that can improve drug distribution to the liver in general are urgently needed. In this review, we summarize current strategies for targeted delivery of drugs to the liver and in particular to pro-fibrogenic liver cells. The applicability and efficacy of sequestering molecules, selective protein carriers, lipid-based drug vehicles, viral vectors, transcriptional targeting approaches, therapeutic liver- and HSC-specific nanoparticles, and miRNA-based strategies are discussed. Some of these delivery systems that had already been successfully tested in experimental animal models of ongoing hepatic fibrogenesis are expected to translate into clinically useful therapeutics specifically targeting HSCs.

Experimentally-derived fibroblast gene signatures identify molecular pathways associated with distinct subsets of systemic sclerosis patients in three independent cohorts

Genome-wide expression profiling in systemic sclerosis (SSc) has identified four ‘intrinsic’ subsets of disease (fibroproliferative, inflammatory, limited, and normal-like), each of which shows deregulation of distinct signaling pathways; however, the full set of pathways contributing to this differential gene expression has not been fully elucidated. Here we examine experimentally derived gene expression signatures in dermal fibroblasts for thirteen different signaling pathways implicated in SSc pathogenesis. These data show distinct and overlapping sets of genes induced by each pathway, allowing for a better understanding of the molecular relationship between profibrotic and immune signaling networks. Pathway-specific gene signatures were analyzed across a compendium of microarray datasets consisting of skin biopsies from three independent cohorts representing 80 SSc patients, 4 morphea, and 26 controls. IFNα signaling showed a strong association with early disease, while TGFβ signaling spanned the fibroproliferative and inflammatory subsets, was associated with worse MRSS, and was higher in lesional than non-lesional skin. The fibroproliferative subset was most strongly associated with PDGF signaling, while the inflammatory subset demonstrated strong activation of innate immune pathways including TLR signaling upstream of NF-κB. The limited and normal-like subsets did not show associations with fibrotic and inflammatory mediators such as TGFβ and TNFα. The normal-like subset showed high expression of genes associated with lipid signaling, which was absent in the inflammatory and limited subsets. Together, these data suggest a model by which IFNα is involved in early disease pathology, and disease severity is associated with active TGFβ signaling.

Comparative Evaluation of Anti-Inflammatory Activity of Curcuminoids, Turmerones, and Aqueous Extract of Curcuma longa

Curcuma longa is widely known for its anti-inflammatory activity in traditional system of medicine for centuries and has been scientifically validated extensively. The present study was conducted to evaluate the anti-inflammatory activity of curcuminoids and oil-free aqueous extract (COFAE) of C. longa and compare it with that of curcuminoids and turmerones (volatile oil), the bioactive components of C. longa that are proven for the anti-inflammatory potential. The activity against inflammation was evaluated in xylene-induced ear edema, cotton pellet granuloma models in albino Swiss mice and albino Wistar rats, respectively. The results showed that COFAE of C. longa at three dose levels significantly (P ≤ 0.05) inhibited inflammation in both models, as evidenced by reduction in ear weight and decrease in wet as well as dry weights of cotton pellets, when compared to the vehicle control. The COFAE of C. longa showed considerable anti-inflammatory effects against acute and chronic inflammation and the effects were comparable to those of curcuminoids and turmerones.

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.

Low concentration of PDGF-AB shows synergism with IFN-α in induction of IFN-β and -γ in MRC5 fibroblasts

Platelet-derived growth factor (PDGF) is a potent mediator of fibroblast proliferation and chemotaxis. Also it has been reported as a strong suppressor of interferon (IFN) expression. IFN-α has opposite effect on fibroblast function and IFN induction. Here is our early report on the effect of low concentration of PDGF-AB alone or in combination with IFN-α on IFN mRNA production in MRC5 fibroblasts. MRC5 cells incubated with IFN-α or PDGF-AB, alone or in combination, produced significant induction of IFN-α, -β and -γ mRNA in comparison with untreated cells. The induction was dose-dependent, with higher effect in cells treated with lower concentrations of PDGF-AB. Also, low concentration of PDGF-AB showed synergism with IFN-α in IFN-β and -γ induction. Results presented here open new possibilities in multi-cytokine therapy and expand previous results on PDGF activity.

Nonresponse to interferon-α based treatment for chronic hepatitis C infection is associated with increased hazard of cirrhosis

Background

The long-term consequences of unsuccessful interferon-α based hepatitis C treatment on liver disease progression and survival have not been fully explored.

Methods and Findings

We performed retrospective analyses to assess long-term clinical outcomes among treated and untreated patients with hepatitis C virus in two independent cohorts from a United States Veterans Affairs Medical Center and a University Teaching Hospital. Eligible patients underwent liver biopsy during consideration for interferon-α based treatment between 1992 and 2007. They were assessed for the probability of developing cirrhosis and of dying during follow-up using Cox proportional hazards models, stratified by pretreatment liver fibrosis stage and adjusted for known risk factors for cirrhosis and characteristics affecting treatment selection. The major predictor was a time-dependent covariate for treatment outcome among four patient groups: 1) patients with sustained virological response to treatment; 2) treatment relapsers; 3) treatment nonresponders; and 4) never treated patients. Treatment nonresponders in both cohorts had a statistically significantly increased hazard of cirrhosis compared to never treated patients, as stratified by pretreatment liver fibrosis stage and adjusted for clinical and psychosocial risk factors that disproportionately affect patients who were ineligible for treatment (Veterans Affairs HR = 2.35, CI 1.18–4.69, mean follow-up 10 years, and University Hospital HR = 5.90, CI 1.50–23.24, mean follow-up 7.7 years). Despite their increased risk for liver disease progression, the overall survival of nonresponders in both cohorts was not significantly different from that of never treated patients.

Conclusion

These unexpected findings suggest that patients who receive interferon-α based therapies but fail to clear the hepatitis C virus may have an increased hazard of cirrhosis compared to untreated patients.

Anti-fibrotic therapy: lost in translation?

While preclinical development of potential anti-fibrotics is far advanced, with numerous pharmacological targets and promising agents, almost none has entered clinical validation. Reasons are manifold, including the usually slow progression of liver fibrosis, requiring high numbers of well-stratified patients undergoing long-term treatment when conventional liver biopsy based parameters or hard liver-related endpoints are used. Importantly, there is a notorious lack of sensitive and specific surrogate markers or imaging technologies for liver fibrosis progression or regression that would permit a rapid clinical screening for potential anti-fibrotics. Nonetheless, in view of an urgent need for anti-fibrotics that positively impact morbidity and mortality from chronic liver diseases, the field is now moving more quickly towards clinical translation. This development is driven by thoughtful preclinical validation, a better study design and improved surrogate readouts using currently available methodologies. Moreover, upcoming novel biomarkers and imaging technologies will soon permit a more exact and efficient assessment of fibrosis progression and regression.

Down-regulation of cyclin E1 expression by microRNA-195 accounts for interferon-β-induced inhibition of hepatic stellate cell proliferation

Recent studies have suggested that interferons (IFNs) have an antifibrotic effect in the liver independent of their antiviral effect although its detailed mechanism remains largely unknown. Some microRNAs have been reported to regulate pathophysiological activities of hepatic stellate cells (HSCs). We performed analyses of the antiproliferative effects of IFNs in HSCs with special regard to microRNA-195 (miR-195). We found that miR-195 was prominently down-regulated in the proliferative phase of primary-cultured mouse HSCs. Supporting this fact, IFN-β induced miR-195 expression and inhibited the cell proliferation by delaying their G1 to S phase cell cycle progression in human HSC line LX-2. IFN-β down-regulated cyclin E1 and up-regulated p21 mRNA levels in LX-2 cells. Luciferase reporter assay revealed the direct interaction of miR-195 with the cyclin E1 3'UTR. Overexpression of miR-195 lowered cyclin E1 mRNA and protein expression levels, increased p21 mRNA and protein expression levels, and inhibited cell proliferation in LX-2 cells. Moreover miR-195 inhibition restored cyclin E1 levels that were down-regulated by IFN-β. In conclusion, IFN-β inhibited the proliferation of LX-2 cells by delaying cell cycle progression in G1 to S phase, partially through the down-regulation of cyclin E1 and up-regulation of p21. IFN-induced miR-195 was involved in these processes. These observations reveal a new mechanistic aspect of the antifibrotic effect of IFNs in the liver.

Toll-like receptor 3 in liver diseases

Toll-like receptor 3 (TLR3) is a member of the TLR family that can recognize double-stranded RNA (dsRNA), playing an important role in antiviral immunity. Recent studies have shown that TLR3 is also expressed on parenchymal and nonparenchymal cells in the liver as well as on several types of immune cells. In this review, we summarize the role of TLR3 in liver injury, inflammation, regeneration, and liver fibrosis, and discuss the implication of TLR3 in the pathogenesis of human liver diseases including viral hepatitis and autoimmune liver disease.

Investigating the role of the extracellular environment in modulating hepatic stellate cell biology with arrayed combinatorial microenvironments

Hepatic stellate cells (HSCs) are a major cell type of the liver that are involved in liver homeostasis. Upon liver damage, HSCs exit their normally quiescent state and become activated, leading to an increase of their proliferation, production of abnormal extracellular matrix proteins (ECMPs) and inflammatory mediators, and eventually liver fibrosis and cirrhosis. Current in vitro approaches to identify components that influence HSC biology typically investigate one factor at a time and generally ignore the complex crosstalk among the myriad of components that comprise the microenvironments of quiescent or activated HSCs. Here we describe a high throughput screening (HTS) approach to identify factors that affect HSC biology. Specifically, we integrated the use of ECMPs and signaling molecules into a combinatorial cellular microarray technology platform, thereby creating comprehensive "microenvironments". Using this technology, we performed real-time simultaneous screening of the effects of hundreds of unique microenvironments composed of ECMPs and signaling molecules on HSC proliferation and activation. From these screens, we identified combinations of microenvironment components that differentially modulate the HSC phenotype. Furthermore, analysis of HSC responses revealed that the influences of Wnt signaling molecules on HSC fate are dependent on the ECMP composition in which they are presented. Collectively, our results demonstrate the utility of high-content, array-based screens to provide a better understanding of HSC biology. Our results indicate that array-based screens may provide an efficient means for identifying candidate signaling pathways to be targeted for anti-fibrotic therapies.

[Liver fibrosis: from pathophysiology to therapeutic openings]

Understanding of liver fibrosis pathogenesis has undergone tremendous advances over the past twenty years. In this respect, demonstration of the reversibility of fibrosis was a major turnpoint. The panel of therapeutic targets is continuously expanding. Clinical development has however remained limited, heretofore, but should rapidly progress owing to the availability of accurate non-invasive methods for assessment of fibrosis, to improvement in the selection patients included in therapeutic trials, and to the development of cell specific targeting devices for agents at risk of adverse effects.

Effect of natural interferon α on proliferation and apoptosis of hepatic stellate cells

Inhibition of the proliferation of hepatic stellate cells (HSC) is clinically important for the control of liver fibrosis and cirrhosis. Interferons are now frequently used for chronic viral hepatitis because of their anti-viral activity. However, patients treated with interferons exhibit a regression of liver fibrosis even if viral eradication is not achieved, indicating that interferon itself has anti-fibrotic activity. Herein, we show the anti-proliferation and pro-apoptotic activity of natural interferon α against HSC. We found that interferon α inhibited serum-stimulated [(3)H]thymidine incorporation of HSC in a dose-dependent manner, with a significant reduction at more than 100 U/ml. Interferon α also attenuated PDGF-BB-stimulated DNA synthesis of HSC. Although the molecular mechanism behind these phenomena has not been defined, we found that interferon α triggers the apoptosis of HSC treated with low-dose tumor necrosis factor α, as determined by the Alamar blue assay, morphology, and DNA ladder formation. Furthermore, interferon α decreased inhibitor of caspase-activated DNase (ICAD) levels, which may augment tumor necrosis factor α-induced cell death signals. Thus, interferon α regulates the number of myofibroblastic hepatic stellate cells and may clinically contribute to the regression of human liver fibrosis.

An independent and prospective comparison of two commercial fibrosis marker panels (HCV FibroSURE and FIBROSpect II) during albinterferon alfa-2b combination therapy for chronic hepatitis C

Noninvasive markers that accurately follow changes in fibrosis may provide alternatives to liver biopsy for assessment of histological endpoints of antiviral therapy in chronic hepatitis C (CHC). This study compared two commercially available serum marker panels (HCV FibroSURE and FIBROSpect II) during interferon-based therapy. Ninety-five interferon-naïve patients with genotype 1 CHC were enrolled in a phase 2b, active-controlled study of albinterferon alfa-2b/ribavirin for 48 weeks. Proprietary and simple biochemical marker panels were independently evaluated in serum before and during the study. Baseline liver biopsies were evaluated for METAVIR fibrosis by a single pathologist. Index scores were obtained for HCV FibroSURE (n = 84) and FIBROSpect II (n = 95); mean biopsy length: 17.8 +/- 8.0 mm. For detecting fibrosis stages 2-4 (prevalence 23% [22/95] and 21% [18/84]), HCV FibroSURE and FIBROSpect II indicated high sensitivity (1.00 and 0.95, respectively), lower but comparable specificity (0.61 and 0.66, respectively), and a good area under the receiver operating characteristic curve (0.89 and 0.90, respectively). Simple indices had high indeterminate rates (31-40%) at baseline. Patients with a sustained virological response had lower baseline scores than nonresponders, and reduced median percent changes in index scores for HCV FibroSURE (-20.0%vs 2.9%; P = 0.14) and FIBROS Spect II (-6.8%vs 18.4%; P = 0.05). The panels demonstrated comparable performance characteristics for differentiating mild from moderate-severe stage disease in CHC. Lower index scores at baseline that continue to decline likely reflect reduced fibrogenesis activity in patients with successful antiviral responses to therapy.

Modulation of the BCL-2/BAX ratio by interferon-γ and hypoxia in human peritoneal and adhesion fibroblasts

OBJECTIVE

To examine the effect of interferon (IFN)-gamma treatment under normal and hypoxic conditions on the BCL-2/BAX ratio of fibroblasts obtained from normal peritoneal and adhesion tissues of the same patients.

DESIGN

Prospective experimental study.

SETTING

University medical center.

PATIENT(S)

Fibroblasts from peritoneum and adhesion tissues of 5 patients.

INTERVENTION(S)

Hypoxia and IFN-gamma treatments of fibroblasts.

MAIN OUTCOME MEASURE(S)

We used the multiplex polymerase chain reaction technique to measure expression of BCL-2 and BAX in normal peritoneal and adhesion fibroblasts exposed to hypoxia (2% O(2)), in the presence or absence of IFN-gamma for different time points and dosages.

RESULT(S)

At baseline, adhesion fibroblasts manifested decreased basal levels of apoptosis compared with normal fibroblasts. Hypoxia treatment resulted in a time-response decrease in apoptosis in both cell lines. Interferon-gamma treatment resulted in a dose-response increase in apoptosis in both cell lines. Hypoxia had a reduced or no effect on apoptosis in the presence of increasing doses of IFN-gamma in both cell types.

CONCLUSION(S)

Interferon-gamma can block the effects of hypoxia on apoptosis, supporting the antifibrogenic nature of this cytokine. This suggests that IFN-gamma would be a good candidate for consideration for intervention in the development of peritoneal adhesions and fibrosis.

Hepatitis C: current options for nonresponders to peginterferon and ribavirin

Hepatitis C virus infection remains a significant health problem worldwide. The development of interferon-based therapies has led to increased success in eradicating this viral infection; however, no recent additions to the current treatment care regimen (peginterferon and ribavirin) have been made. Nonresponders to peginterferon/ribavirin make up a diverse patient population that can be difficult to manage. Through a better understanding of treatment response and viral kinetics, clinicians are employing altered dosing schedules to minimize the burden of viral illness. Consequently, clinicians can now manage nonresponders by providing supportive care and reserving retreatment for those most likely to respond to additional antiviral therapy, particularly when correctable factors from a previous treatment course with the potential for positive intervention have been identified. The decision for further medical management is based on clinical and laboratory parameters that have been shown to predict which patients will benefit most from another attempt at therapy.

Regulatory role of interleukin-10 and interferon-gamma in severe hepatic central and peripheral fibrosis in humans infected with Schistosoma japonicum

BACKGROUND

Schistosoma japonicum is the most pathogenic agent of hepatosplenic schistosomiasis. It causes fibrosis of the central (CentF) and peripheral (PerF) portal areas. We investigated whether CentF and PerF in Chinese fishermen infected with S. japonicum were associated with an abnormal production of cytokines and chemokines that, in experimental models, have been implicated in the regulation of fibrosis.

METHODS

Cytokines were measured by enzyme-linked immunosorbent assay in cultures of peripheral blood mononuclear cells from 127 patients, after stimulation with S. japonicum egg antigens. Data were analyzed by logistic regression that included age, sex, number of treatment episodes, alcohol use, and exposure as covariates.

RESULTS

CentF was associated with low levels of interleukin (IL)-10 (P= .0004), regulated on activation normally T cell expressed and secreted (P= .0004), and macrophage inflammatory protein-1alpha (P= .007). In a multivariate analysis, only IL-10 was associated with CentF (odds ratio [OR], 10.8; 95% confidence interval [CI], 3.2-38; P= .0004). Splenomegaly was also associated with low IL-10 production and, independently, with CentF. In multivariate analysis, PerF was associated with low production of interferon (IFN)-gamma (OR, 8.2; 95% CI, 2-33; P= .0035) but not with production of IL-10.

CONCLUSIONS

IL-10 is associated with protection against central fibrosis, because of its anti-inflammatory and antifibrosis effects. IFN-gamma is associated with protection against PerF, which depends more on egg load and egg-associated toxicity.

Histological benefits of virological response to peginterferon alfa-2a monotherapy in patients with hepatitis C and advanced fibrosis or compensated cirrhosis

BACKGROUND

Patients with chronic hepatitis C virus and advanced fibrosis or cirrhosis are at risk for disease progression and hepatic decompensation.

AIM

To determine the effects on hepatic histology of treatment with peginterferon alfa-2a (90 or 180 mug/week) or interferon alfa-2a (3 million units three times weekly) for 48 weeks in patients with paired biopsies.

METHODS

Liver biopsies were obtained at baseline and 6 months after end of treatment. Histological and virological responses were compared.

RESULTS

Patients attaining sustained virological response (n = 40) demonstrated the greatest improvements in fibrosis (-1.0, P < 0.0001) and inflammation (-0.65, P < 0.0001). Patients who cleared hepatitis C virus during treatment, but later relapsed (n = 59), experienced less improvement in fibrosis (-0.04, P < 0.0001) and inflammation (-0.14, P = 0.0768). Nonresponders (n = 85) showed no significant improvement in inflammation or fibrosis. Multiple regression analysis showed that the only factors contributing to improvement in fibrosis were sustained virological response (vs. nonresponder, P = 0.0005; vs. relapse, P = 0.7525) and body mass index < or =30 kg/m2 (P = 0.0995).

CONCLUSIONS

These findings indicate that virological response to peginterferon alfa-2a improves inflammation and fibrosis in hepatitis C virus patients with advanced fibrosis or cirrhosis. Improving virological response and maintaining ideal body weight are critical for achieving optimal histological outcomes in hepatitis C virus patients.

Bioconjugation of oligonucleotides for treating liver fibrosis

Liver fibrosis results from chronic liver injury due to hepatitis B and C, excessive alcohol ingestion, and metal ion overload. Fibrosis culminates in cirrhosis and results in liver failure. Therefore, a potent antifibrotic therapy is urgently needed to reverse scarring and eliminate progression to cirrhosis. Although activated hepatic stellate cells (HSCs) remain the principle cell type responsible for liver fibrosis, perivascular fibroblasts of portal and central veins as well as periductular fibroblasts are other sources of fibrogenic cells. This review will critically discuss various treatment strategies for liver fibrosis, including prevention of liver injury, reduction of inflammation, inhibition of HSC activation, degradation of scar matrix, and inhibition of aberrant collagen synthesis. Oligonucleotides (ODNs) are short, single-stranded nucleic acids, which disrupt expression of target protein by binding to complementary mRNA or forming triplex with genomic DNA. Triplex forming oligonucleotides (TFOs) provide an attractive strategy for treating liver fibrosis. A series of TFOs have been developed for inhibiting the transcription of alpha1(I) collagen gene, which opens a new area for antifibrotic drugs. There will be in-depth discussion on the use of TFOs and how different bioconjugation strategies can be utilized for their site-specific delivery to HSCs or hepatocytes for enhanced antifibrotic activities. Various insights developed in individual strategy and the need for multipronged approaches will also be discussed.

Clinical trial: interferon alpha-2b continuous long-term therapy vs. repeated 24-week cycles for re-treating chronic hepatitis C

BACKGROUND

Treatment options are limited for patients with hepatitis C virus who do not experience sustained viral eradication with pegylated interferon and ribavirin therapy.

AIM

To compare, in an open-label, randomized study, long-term continuous interferon alpha-2b treatment with repeated 24-week courses in patients with chronic hepatitis C virus that relapsed after prior interferon monotherapy.

METHODS

A total of 499 patients received 24 weeks of interferon alpha-2b, 3 MIU administered 3 TIW. Responders (normal alanine aminotransferase and negative hepatitis C virus -RNA, n = 244) were then randomized to continuous interferon therapy (1, 2 or 3 MIU TIW depending on response) or cyclical therapy (3 MIU TIW for 24 weeks per relapse). Mean Knodell inflammation (I + II + III) and necrosis (IV) scores at baseline vs. year 2 were compared.

RESULTS

Patients receiving continuous low-dose therapy vs. cycled therapy had larger reductions in inflammation (-3.9 vs. -3.1) and fibrosis (-0.49 vs. -0.24). Among both groups, the mean change was -3.4 for inflammation and -0.36 for fibrosis. Overall, 73% (95% CI: 67-79) of patients experienced reduced inflammation and 28% (95% CI: 22-34) had reduced fibrosis.

CONCLUSIONS

Our results suggest hepatitis C virus patients experiencing viral suppression during long-term maintenance therapy with interferon demonstrate histological improvement. Further prospective trials testing this hypothesis are in progress.

Activation of natural killer cells inhibits liver fibrosis: a novel strategy to treat liver fibrosis

Liver lymphocytes are enriched in natural killer (NK) cells, which are involved in innate immune defenses against viral infection and tumor transformation in the liver. Recent evidence indicates that NK cell activation by IFN-alpha, IFN-gamma or dsRNA attenuates liver fibrosis through the direct killing of activated hepatic stellate cells (HSCs). Interestingly, NK cells do not kill quiescent or fully activated HSCs, but only early-activated HSCs, as only these cells express elevated levels of the NK cell-activating ligand retinoic acid-induced early transcript (RAE)-1 and TNF-related apoptosis-inducing ligand receptors, in addition to downregulated levels of the NK-cell inhibitory ligand, MHC-I. Inhibition of liver fibrosis by NK cells can also be achieved through production of IFN-gamma, which induces HSC cell cycle arrest and apoptosis in a STAT1-dependent manner. Clinically, it has also been observed that NK cell activity is negatively correlated with liver fibrosis in patients with chronic hepatitis C infection. Therefore, since NK cells inhibit liver fibrosis, stimulating NK activity could potentially be a novel strategy to treat liver fibrosis. Clinical studies will be required to confirm whether stimulating NK cell activity is effective and safe in treating human liver fibrosis.

Influence of pretransplant IFN-alpha therapy on interstitial fibrosis in renal allografts with hepatitis C virus infection

The aim of this study is to identify the influence of chronic HCV infection on development of interstitial fibrosis (IF) in renal allografts and evaluate if pretransplant interferon-alpha (IFN-alpha) therapy has an effect on IF. The development of IF and graft outcome were compared between anti-HCV positive (n = 28) and anti-HCV negative (n = 30) recipients. The influence of IFN-alpha therapy on IF and graft survival was compared between anti-HCV positive recipients who received pre-transplant IFN-alpha therapy (n = 15, group 1) and anti-HCV positive recipients who did not receive IFN-alpha therapy (n = 13, group 2). Recipients with anti-HCV antibodies had higher incidences of IF and shorter graft survival than did recipients without anti-HCV antibodies (p < 0.05 for both). Development of IF was higher in group 2 recipients, and patients in group 1 had longer graft survivals (p < 0.05 for both). Patients with positive HCV-RNA had higher grades of tubular TGF-beta1 expression than did patients with negative HCV-RNA (p < 0.05). Expression of tubular TGF-beta1 was lower in group 1 patients when compared with group 2 patients (p < 0.001). In conclusion, we suggested that HCV infection may have a triggering effect on the development of IF in renal allografts by augmenting renal expression of TGF-beta1.

IFN-gamma abrogates profibrogenic TGF-beta signaling in liver by targeting expression of inhibitory and receptor Smads

BACKGROUND/AIMS

In a randomized open-labeled multicenter trial with patients suffering from chronic HBV infection, we recently identified a benefit of 9-month IFN-gamma treatment resulting in decreased fibrosis scores and a reduced number of alpha-smooth muscle actin-positive hepatic stellate cells (HSCs). Approaches opposing profibrogenic activities of TGF-beta may be amenable in chronic liver disease. According to experimental models, IFN-gamma counteracts several TGF-beta effects.

METHODS

The crosstalk of IFN-gamma and TGF-beta signaling relevant for fibrogenesis was investigated in primary cultured rat HSCs and a cell line representing activated HSCs.

RESULTS

In vitro studies with HSCs demonstrate that TGF-beta-dependent activation of (CAGA)9-MLP-Luc, a Smad3/4 responsive reporter construct, was significantly decreased by IFN-gamma, indicating a TGF-beta antagonizing function. IFN-gamma induced the activity of the Smad7 promoter and Smad7 protein expression via STAT-1 signaling. In contrast to TGF-beta, IFN-gamma was able to induce Smad7 expression in activated HSCs providing increased protein levels for at least 12h. In addition, expression of Smad2/3 was reduced by IFN-gamma and activation of Smads2/3 was abrogated.

CONCLUSIONS

IFN-gamma displays antifibrotic effects in liver cells via STAT-1 phosphorylation, upregulation of Smad7 expression and impaired TGF-beta signaling.

Present and future therapy for hepatitis C virus

The treatment of hepatitis C virus (HCV) infection has developed enormously over recent years. Early treatment of acute HCV infection with interferon-alpha can prevent chronicity and a significant proportion of patients with chronic HCV can be cured with the current standard therapy consisting of pegylated interferon-alpha and ribavirin. However, the improvement of current treatment regimens and the development of new antiviral drugs will be essential within the next few years. This review focuses on the present and future concepts for treating HCV infection, including prevention of infection, antiviral therapy of acute and chronic HCV and the management of patients after liver transplantation.

STAT1 inhibits liver fibrosis in mice by inhibiting stellate cell proliferation and stimulating NK cell cytotoxicity

Liver fibrosis, a common scarring response to chronic liver injury, is a precursor to cirrhosis and liver cancer. Here, we identified signal transducer and activator of transcription 1 (STAT1) as an important negative regulator in liver fibrosis. Our findings show that disruption of the STAT1 gene accelerated liver fibrosis and hepatic stellate cell (HSC) proliferation in an in vivo model of carbon tetrachloride (CCl4)-induced liver fibrosis. In vitro treatment with IFN-gamma inhibited proliferation and activation of wild-type HSCs, but not STAT1-/- HSCs. Moreover, compared to wild-type cells, cellular proliferation stimulated by serum or platelet-derived growth factor (PDGF) was enhanced and accelerated in STAT1-/- HSCs, which was partially mediated via elevated PDGF receptor beta expression on such cells. Polyinosinic-polycytidylic acid (poly I:C) or IFN-gamma treatment inhibited liver fibrosis in wild-type mice but not in STAT1-/- mice. Induction of NK cell killing of activated HSCs by poly I:C was attenuated in STAT1-/- mice compared to wild-type mice, which was likely due to reduced NKG2D and TRAIL expression on STAT1-/- NK cells. Finally, activation of TGF-beta/Smad3 signaling pathway was accelerated, whereas induction of Smad7 was diminished in the liver of STAT1-/- mice after CCl4 administration compared to wild-type mice. In conclusion, activation of STAT1 attenuates liver fibrosis through inhibition of HSC proliferation, attenuation of TGF-beta signaling, and stimulation of NK cell killing of activated HSCs. STAT1 could be a new therapeutic target for treating liver fibrosis.

Hépatite C et transplantation hépatique

Hepatitis C virus-related end-stage liver disease, alone or in combination with alcohol, has become the leading indication for liver transplantation in most transplant programs accounting for approximately half of transplants performed in European centers. Hepatitis C virus infection recurs virtually in every post-transplant patient. The natural history of hepatitis C after liver transplantation is variable. Progression of chronic hepatitis C virus is more aggressive after liver transplantation with a cumulative probability of developing graft cirrhosis estimated to reach 30% at 5 years. Approximately 10% of the patients with recurrent disease will die or require re-transplantation within 5 years post-transplantation. Several factors, including those related to the virus, the host, the environment and the donor, are probably implicated in the outcome. The immune status represents the main significant variable in influencing disease severity in hepatitis C virus-infected patients; with higher HCV viral load and the significant association described between the degree of immunosuppression and disease severity. Interventions to prevent, improve, or halt the recurrence of hepatitis C virus infection have been evaluated by multiple small studies worldwide with similar overall rates of virological clearance of approximately 9-30%. Current consensus recommends combination therapy with pegylated interferon and ribavirin for those patients with histological recurrence of hepatitis C virus infection and fibrosis. Therapy is adjusted to tolerance and rescued with granulocyte colony-stimulating factor and erythropoietin for bone marrow suppression. In this article we present a comprehensive review of post-transplant hepatitis C virus infection; in particular fibrosis progression and the major challenges according to treatment.

Mendelian and complex genetics of susceptibility and resistance to parasitic infections

Uncovering the complex genetic basis of susceptibility and resistance to parasitic infectious diseases is an enormous challenge. It probably involves many different host genes, interacting with multiple parasite genetic and environmental factors. Several genes of interest have been identified by family and association studies in humans and by using mouse models, but more robust epidemiological studies and functional data are needed to authenticate these findings. With new technologies and statistical tools for whole-genome association analysis, the next few years are likely to see acceleration in the rate of gene discovery, which has the potential to greatly assist drug and vaccine development.

Direct and indirect evidence for the reversibility of cirrhosis

The aim of this study was to assess the reversibility of cirrhosis after therapy in a large series of patients with cirrhosis from various etiologies. We performed a retrospective study of 113 patients with biopsy-proven cirrhosis who underwent specific therapy and follow-up biopsies. Two pathologists performed blinded analyses of indirect biochemical and morphological signs of cirrhosis. Fourteen (12.4%) of the 113 cirrhotic patients had biopsy-proven disappearance of cirrhosis, defined as a decrease of 2 or greater in their METAVIR fibrosis score: 8 were related to hepatitis C virus, 3 to hepatitis B virus, and 3 to autoimmune cirrhosis. Necro-inflammatory activity decreased from 2.4 +/- 0.65 to 0.85 +/- 0.9 (P = .004), and fibrosis from 4 to 1.7 +/- 0.61 (P = .001). Prothrombin time (n = 1), platelet count (n = 2), serum albumin level (n = 2), and ultrasound abnormalities (n = 6) normalized in patients who had initial abnormalities. Hyaluronic acid and procollagen type III serum level decreased in all. In the 11 patients with regression of viral cirrhosis, 2 were nonresponders and 9 were responders, including 2 relapsers. The 3 patients with regressive autoimmune cirrhosis were complete responders to immunosupressive therapy. Using repeated liver biopsies, clinicobiochemical, radiologic, and endoscopic tests, we provide evidence for potential reversibility of cirrhosis after long-lasting suppression of the necro-inflammatory activity of liver disease.

Natural killer cells ameliorate liver fibrosis by killing activated stellate cells in NKG2D-dependent and tumor necrosis factor-related apoptosis-inducing ligand-dependent manners

BACKGROUND & AIMS

Viral hepatitis infection, which is a major cause of liver fibrosis, is associated with activation of innate immunity. However, the role of innate immunity in liver fibrosis remains obscure.

METHODS

Liver fibrosis was induced either by feeding mice with the 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet or by injecting them with carbon tetrachloride. The Toll-like receptor 3 ligand, polyinosinic-polycytidylic acid, was used to activate innate immunity cells and mediators, including natural killer cells and interferon gamma.

RESULTS

In the mouse model of DDC-induced liver fibrosis, natural killer cell activation by polyinosinic-polycytidylic acid induced cell death to activated hepatic stellate cells and attenuated the severity of liver fibrosis. Polyinosinic-polycytidylic acid treatment also ameliorated liver fibrosis induced by carbon tetrachloride. The observed protective effect of polyinosinic-polycytidylic acid on liver fibrosis was diminished through either depletion of natural killer cells or by disruption of the interferon gamma gene. Expression of retinoic acid early inducible 1, the NKG2D ligand, was undetectable on quiescent hepatic stellate cells, whereas high levels were found on activated hepatic stellate cells, which correlated with the resistance and susceptibility of quiescent hepatic stellate cells and activated hepatic stellate cells to natural killer cell lysis, respectively. Moreover, treatment with polyinosinic-polycytidylic acid or interferon gamma enhanced the cytotoxicity of natural killer cells against activated hepatic stellate cells and increased the expression of NKG2D and tumor necrosis factor-related apoptosis-inducing ligand on liver natural killer cells. Blocking NKG2D or tumor necrosis factor-related apoptosis-inducing ligand with neutralizing antibodies markedly diminished the cytotoxicity of polyinosinic-polycytidylic acid-activated natural killer cells against activated hepatic stellate cells.

CONCLUSIONS

Our findings suggest that natural killer cells kill activated hepatic stellate cells via retinoic acid early inducible 1/NKG2D-dependent and tumor necrosis factor-related apoptosis-inducing ligand-dependent mechanisms, thereby ameliorating liver fibrosis.

Future trends in hepatitis C therapy

The development of new treatment strategies for the therapy of hepatitis C is an unmet need. There has already been an enormous improvement in the therapy of chronic hepatitis C since the early 1990s, but the sustained virologic response rates are still unsatisfactory for certain patient groups. Novel therapeutic strategies, especially for the difficult-to-treat patients, are currently being tested. This review discusses the latest achievements in the treatment of chronic heptatis C.