Immune interactions in hepatic fibrosis

Transcriptomic evaluation of N6-methyladenosine modification can be used to identify differentially gene and immune-related biological processes in TX mice with liver fibrosis

BACKGROUND

N6-methyladenosine (m6A) modification controls the stability, splicing, and translation of mRNA, which is important in the development of illnesses. Wilson's disease (WD) is an autosomal recessive liver copper metabolic disorder that causes liver fibrosis. The role of m6A methylation in WD-induced liver fibrosis development is still unclear. Thus, the goal of this study was to examine the scope of m6A methylation and further explore the potential targets related to WD-induced liver fibrosis.

RESULTS

A total of 1930 significantly different m6A peaks were found on 1737 mRNAs, of which 993 were hypermethylated and 744 were hypomethylated when comparing normal and WD-induced liver fibrosis mice (n = 3). In parallel, 1261 differentially expressed mRNAs, comprising 557 upregulated and 704 downregulated mRNAs, were found. Overall, 114 mRNAs with significant changes in m6A levels and RNA expression were identified via joint analysis. Then, through PPI network construction and functional enrichment analysis, 12 hub genes were identified, these genes were mainly enriched in the inflammatory response and immunomodulation, and they are associated with immune cell infiltration.

CONCLUSIONS

The significant difference in the amount of mRNA m6A modifications indicates that m6A modification is involved in the progression of WD-induced liver fibrosis, and theidentified hub genes are involved in inflammation and immune infiltration. These results may provide insights for subsequent studies on potential regulatory mechanisms.

Mechanism and Progress of Natural Products in the Treatment of NAFLD-Related Fibrosis

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most prevalent chronic liver disorder worldwide, with liver fibrosis (LF) serving as a pivotal juncture in NAFLD progression. Natural products have demonstrated substantial antifibrotic properties, ushering in novel avenues for NAFLD treatment. This study provides a comprehensive review of the potential of natural products as antifibrotic agents, including flavonoids, polyphenol compounds, and terpenoids, with specific emphasis on the role of Baicalin in NAFLD-associated fibrosis. Mechanistically, these natural products have exhibited the capacity to target a multitude of signaling pathways, including Hedgehog, Wnt/β-catenin, TGF-β1, and NF-κB. Moreover, they can augment the activities of antioxidant enzymes, inhibit pro-fibrotic factors, and diminish fibrosis markers. In conclusion, this review underscores the considerable potential of natural products in addressing NAFLD-related liver fibrosis through multifaceted mechanisms. Nonetheless, it underscores the imperative need for further clinical investigation to authenticate their effectiveness, offering invaluable insights for future therapeutic advancements in this domain.

The senescent secretome drives PLVAP expression in cultured human hepatic endothelial cells to promote monocyte transmigration

Liver sinusoidal endothelial cells (LSEC) undergo significant phenotypic change in chronic liver disease (CLD), and yet the factors that drive this process and the impact on their function as a vascular barrier and gatekeeper for immune cell recruitment are poorly understood. Plasmalemma-vesicle-associated protein (PLVAP) has been characterized as a marker of LSEC in CLD; notably we found that PLVAP upregulation strongly correlated with markers of tissue senescence. Furthermore, exposure of human LSEC to the senescence-associated secretory phenotype (SASP) led to a significant upregulation of PLVAP. Flow-based assays demonstrated that SASP-driven leukocyte recruitment was characterized by paracellular transmigration of monocytes while the majority of lymphocytes migrated transcellularly. Knockdown studies confirmed that PLVAP selectively supported monocyte transmigration mediated through PLVAP's impact on LSEC permeability by regulating phospho-VE-cadherin expression and endothelial gap formation. PLVAP may therefore represent an endothelial target that selectively shapes the senescence-mediated immune microenvironment in liver disease.

MANF brakes TLR4 signaling by competitively binding S100A8 with S100A9 to regulate macrophage phenotypes in hepatic fibrosis

The mesencephalic astrocyte-derived neurotrophic factor (MANF) has been recently identified as a neurotrophic factor, but its role in hepatic fibrosis is unknown. Here, we found that MANF was upregulated in the fibrotic liver tissues of the patients with chronic liver diseases and of mice treated with CCl4. MANF deficiency in either hepatocytes or hepatic mono-macrophages, particularly in hepatic mono-macrophages, clearly exacerbated hepatic fibrosis. Myeloid-specific MANF knockout increased the population of hepatic Ly6Chigh macrophages and promoted HSCs activation. Furthermore, MANF-sufficient macrophages (from WT mice) transfusion ameliorated CCl4-induced hepatic fibrosis in myeloid cells-specific MANF knockout (MKO) mice. Mechanistically, MANF interacted with S100A8 to competitively block S100A8/A9 heterodimer formation and inhibited S100A8/A9-mediated TLR4-NF-κB signal activation. Pharmacologically, systemic administration of recombinant human MANF significantly alleviated CCl4-induced hepatic fibrosis in both WT and hepatocytes-specific MANF knockout (HKO) mice. This study reveals a mechanism by which MANF targets S100A8/A9-TLR4 as a "brake" on the upstream of NF-κB pathway, which exerts an impact on macrophage differentiation and shed light on hepatic fibrosis treatment.

Expression and Function of BMP and Activin Membrane-Bound Inhibitor (BAMBI) in Chronic Liver Diseases and Hepatocellular Carcinoma

BAMBI (bone morphogenetic protein and activin membrane-bound inhibitor) is a transmembrane pseudoreceptor structurally related to transforming growth factor (TGF)-β type 1 receptors (TGF-β1Rs). BAMBI lacks a kinase domain and functions as a TGF-β1R antagonist. Essential processes such as cell differentiation and proliferation are regulated by TGF-β1R signaling. TGF-β is the best-studied ligand of TGF-βRs and has an eminent role in inflammation and fibrogenesis. Liver fibrosis is the end stage of almost all chronic liver diseases, such as non-alcoholic fatty liver disease, and at the moment, there is no effective anti-fibrotic therapy available. Hepatic BAMBI is downregulated in rodent models of liver injury and in the fibrotic liver of patients, suggesting that low BAMBI has a role in liver fibrosis. Experimental evidence convincingly demonstrated that BAMBI overexpression is able to protect against liver fibrosis. Chronic liver diseases have a high risk of hepatocellular carcinoma (HCC), and BAMBI was shown to exert tumor-promoting as well as tumor-protective functions. This review article aims to summarize relevant studies on hepatic BAMBI expression and its role in chronic liver diseases and HCC.

Revealing immune infiltrate characteristics and potential immune-related genes in hepatic fibrosis: based on bioinformatics, transcriptomics and q-PCR experiments

Background

The occurrence and progression of hepatic fibrosis (HF) is accompanied by inflammatory damage. Immune genes play a pivotal role in fibrogenesis and inflammatory damage in HF by regulating immune cell infiltration. However, the immune mechanisms of HF are inadequately studied. Therefore, this research aims to identify the immune genes and biological pathway which involved in fibrosis formation and inflammatory damage in HF and explore immune target-based therapeutics for HF.

Methods

The expression dataset GSE84044 of HF was downloaded from the GEO database. The crucial module genes for HF were screened according to weighted gene co-expression network analysis (WGCNA). The crucial module genes were mapped to immune-related genes obtained from the ImmPort database to obtain the hepatic fibrosis immune genes (HFIGs). In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses were performed on HFIGs. Then, the protein-protein interaction (PPI) network was conducted on HFIGs and hub genes were identified from the PPI network. Moreover, immune infiltration analysis was performed to identified correlation between hub gene and immune cell infiltration. To verify the reliability of the GSE84044 expression profile data analysis, a rat model of CCl4-induced HF was established, followed by transcriptome sequencing and immunofluorescence analysis and quantitative reverse transcription (q-PCR) experiments were performed in HF rats and normal rat liver tissues. Finally, CMAP platform was used to explore immune target-based therapeutics for HF.

Results

In the bioinformatics analysis of GSE84044 data, 98 HFIGs were screened. These genes were mainly involved in inflammation-related biological pathways such as NOD-like receptor signaling pathway, NF-kappa B signaling pathway, Toll-like receptor signaling pathway and PI3K-Akt signaling pathway. From the PPI network, 10 hub genes were identified, including CXCL8, IL18, CXCL10, CD8A, IL7, PTPRC, CCL5, IL7R, CXCL9 and CCL2. Immune infiltration analysis showed that immune cells like neutrophils, natural killer (NK) cells, macrophages M1 and macrophages M2 were significantly correlated with the hepatic fibrosis process and hub gene expression was significantly correlated with these immune cells. Notably, most of the biological pathways HFIGs riched and all the hub gene expression except CXCL8 were validated in subsequent transcriptome and qRCR experiments. Finally, 15 small molecule compounds with the potential to reverse the high expression of hub genes were screen out as potential therapeutic agents for HF.

Conclusion

The immune genes CXCL8, IL18, CXCL10, CD8A, IL7, PTPRC, CCL5, IL7R, CXCL9 and CCL2 may play an essential role in the fibrosis formation and inflammatory damage in HF. The outcomes of this research provide a basis for the study of the immune mechanisms of HF and contribute to the diagnosis and prevention and treatment of HF in clinical practice.

Hepatoprotective effect of Baicalin against thioacetamide-induced cirrhosis in rats: Targeting NOX4/NF-κB/NLRP3 inflammasome signaling pathways

Aim Liver cirrhosis is the result of a vicious cycle of both chronic oxidative stress and inflammation. NADPH oxidase-4 (NOX4) and its companion, NOD-like receptor protein 3 (NLRP3) inflammasome, are emerging as therapeutic targets of liver fibrosis.

MAIN METHODS

Baicalin (BA), a natural flavone, has been investigated for its therapeutic potential against cirrhosis induced by thioacetamide (TAA) (200 mg/kg, twice/week) for 12 weeks in Sprague-Dawley rats. Two doses of BA were administered (25 and 75 mg/kg/day, orally, a week after TAA was stopped and continued for 4 weeks).

KEY FINDINGS

BA was able to reduce fibrosis visualized by Masson trichrome and immunohistochemical staining of the hepatic α-smooth muscle actin (α-SMA) and transforming growth factor-β1. Moreover, BA was able to ameliorate inflammation by reducing hepatic NLRP3 inflammasome subunits, NLRP3 and caspase-1, both parts of the complex responsible for the activation of different interleukins (IL), measured as IL-1β. In addition, BA was able to reduce hepatic nuclear factor kappa B (NF-κB)-driven inflammation through IL-6. BA targeted inflammation through its anti-oxidant ability evidenced by the enhancement of the hepatic superoxide dismutase (SOD) and reduced glutathione (GSH) activity and level, respectively, and the reduction of both hepatic malondialdehyde (MDA) and nitric oxide (NOx) contents. Treatment with BA significantly decreased TAA-induced elevation in hepatic NOX4, a key enzyme for reactive oxygen species (ROS) generation, as well as, inducible nitric oxide synthase (iNOS).

SIGNIFICANCE

therefore, the study could conclude, the anti-fibrotic effect of BA through TGF- β1/NOX4/NF-κB/NLRP3 pathway, exerting both anti-inflammatory and anti-oxidant effects.

Fibrosis and hepatic regeneration mechanism

Liver cirrhosis is the final stage of continuous hepatic inflammatory activity derived by viral, metabolic or autoimmune origin. In the last years, cirrhosis was considered a unique and static condition; recently was accepted some patients subgroups with different liver injury degrees that coexist under the same diagnosis, with implications about the natural disease history. The liver growth factor (LGF) is a potent in vivo and in vitro mitogenic agent and an inducer of hepatic regeneration (HR) through the hepatocytes DNA synthesis. The clinical implications of the LGF levels in cirrhosis, are not clear and even with having a fundamental role in the liver regeneration processes, the studies suggest that it could be a cirrhosis severity marker, in acute liver failure and in chronic hepatitis. Its role as predictor of mortality in fulminant hepatic insufficiency patients has been suggested. HR is one of the most enigmatic and fascinating biological phenomena. The rapid volume and liver function restoration after a major hepatectomy (>70%) or severe hepatocellular damage and its strict regulation of tissue damage response after the cessation, is an exclusive property of the liver. HR is the clinical applications fundament, such as extensive hepatic resections (>70% of the liver parenchyma), segmental transplantation or living donor transplantation, sequential hepatectomies, isolated portal embolization or associated with in situ hepatic transection, temporary artificial support in acute liver failure and the possible cell therapy clinical applications.

Emerging Insights on the Diverse Roles of Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) in Chronic Liver Diseases: Cholesterol Metabolism and Beyond

Chronic liver diseases are commonly associated with dysregulated cholesterol metabolism. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease of the proprotein convertase family that is mainly synthetized and secreted by the liver, and represents one of the key regulators of circulating low-density lipoprotein (LDL) cholesterol levels. Its ability to bind and induce LDL-receptor degradation, in particular in the liver, increases circulating LDL-cholesterol levels in the blood. Hence, inhibition of PCSK9 has become a very potent tool for the treatment of hypercholesterolemia. Besides PCSK9 limiting entry of LDL-derived cholesterol, affecting multiple cholesterol-related functions in cells, more recent studies have associated PCSK9 with various other cellular processes, including inflammation, fatty acid metabolism, cancerogenesis and visceral adiposity. It is increasingly becoming evident that additional roles for PCSK9 beyond cholesterol homeostasis are crucial for liver physiology in health and disease, often contributing to pathophysiology. This review will summarize studies analyzing circulating and hepatic PCSK9 levels in patients with chronic liver diseases. The factors affecting PCSK9 levels in the circulation and in hepatocytes, clinically relevant studies and the pathophysiological role of PCSK9 in chronic liver injury are discussed.

Recovery from Liver Failure and Fibrosis in a Rat Portacaval Anastomosis Model after Neurointermediate Pituitary Lobectomy

Liver diseases, including cirrhosis, viral hepatitis, and hepatocellular carcinoma, account for approximately two million annual deaths worldwide. They place a huge burden on the global healthcare systems, compelling researchers to find effective treatment for liver fibrosis-cirrhosis. Portacaval anastomosis (PCA) is a model of liver damage and fibrosis. Arginine vasopressin (AVP) has been implicated as a proinflammatory-profibrotic hormone. In rats, neurointermediate pituitary lobectomy (NIL) induces a permanent drop (80%) in AVP serum levels. We hypothesized that AVP deficiency (NIL-induced) may decrease liver damage and fibrosis in a rat PCA model. Male Wistar rats were divided into intact control (IC), NIL, PCA, and PCA+NIL groups. Liver function tests, liver gene relative expressions (IL-1, IL-10, TGF-β, COLL-I, MMP-9, and MMP-13), and histopathological assessments were performed. In comparison with those in the IC and PCA groups, bilirubin, protein serum, and liver glycogen levels were restored in the PCA+NIL group. NIL in the PCA animals also decreased the gene expression levels of IL-1 and COLL-I, while increasing those of IL-10, TGF-β, and MMP-13. Histopathology of this group also showed significantly decreased signs of liver damage with lower extent of collagen deposition and fibrosis. Low AVP serum levels were not enough to fully activate the AVP receptors resulting in the decreased activation of cell signaling pathways associated with proinflammatory-profibrotic responses, while activating cell molecular signaling pathways associated with an anti-inflammatory-fibrotic state. Thus, partial reversion of liver damage and fibrosis was observed. The study supports the crucial role of AVP in the inflammatory-fibrotic processes and maintenance of immune competence. The success of the AVP deficiency strategy suggests that blocking AVP receptors may be therapeutically useful to treat inflammatory-fibrotic liver diseases.

The Provocative Roles of Platelets in Liver Disease and Cancer

Both platelets and the liver play important roles in the processes of coagulation and innate immunity. Platelet responses at the site of an injury are rapid; their immediate activation and structural changes minimize the loss of blood. The majority of coagulation proteins are produced by the liver—a multifunctional organ that also plays a critical role in many processes: removal of toxins and metabolism of fats, proteins, carbohydrates, and drugs. Chronic inflammation, trauma, or other causes of irreversible damage to the liver can dysregulate these pathways leading to organ and systemic abnormalities. In some cases, platelet-to-lymphocyte ratios can also be a predictor of disease outcome. An example is cirrhosis, which increases the risk of bleeding and prothrombotic events followed by activation of platelets. Along with a triggered coagulation cascade, the platelets increase the risk of pro-thrombotic events and contribute to cancer progression and metastasis. This progression and the resulting tissue destruction is physiologically comparable to a persistent, chronic wound. Various cancers, including colorectal cancer, have been associated with increased thrombocytosis, platelet activation, platelet-storage granule release, and thrombosis; anti-platelet agents can reduce cancer risk and progression. However, in cancer patients with pre-existing liver disease who are undergoing chemotherapy, the risk of thrombotic events becomes challenging to manage due to their inherent risk for bleeding. Chemotherapy, also known to induce damage to the liver, further increases the frequency of thrombotic events. Depending on individual patient risks, these factors acting together can disrupt the fragile balance between pro- and anti-coagulant processes, heightening liver thrombogenesis, and possibly providing a niche for circulating tumor cells to adhere to—thus promoting both liver metastasis and cancer-cell survival following treatment (that is, with minimal residual disease in the liver).

Pathophysiology and Treatment Options for Hepatic Fibrosis: Can It Be Completely Cured?

Hepatic fibrosis is a dynamic process that occurs as a wound healing response against liver injury. During fibrosis, crosstalk between parenchymal and non-parenchymal cells, activation of different immune cells and signaling pathways, as well as a release of several inflammatory mediators take place, resulting in inflammation. Excessive inflammation drives hepatic stellate cell (HSC) activation, which then encounters various morphological and functional changes before transforming into proliferative and extracellular matrix (ECM)-producing myofibroblasts. Finally, enormous ECM accumulation interferes with hepatic function and leads to liver failure. To overcome this condition, several therapeutic approaches have been developed to inhibit inflammatory responses, HSC proliferation and activation. Preclinical studies also suggest several targets for the development of anti-fibrotic therapies; however, very few advanced to clinical trials. The pathophysiology of hepatic fibrosis is extremely complex and requires comprehensive understanding to identify effective therapeutic targets; therefore, in this review, we focus on the various cellular and molecular mechanisms associated with the pathophysiology of hepatic fibrosis and discuss potential strategies to control or reverse the fibrosis.

Glucocorticoid-induced leucine zipper regulates liver fibrosis by suppressing CCL2-mediated leukocyte recruitment

Liver fibrosis (LF) is a dangerous clinical condition with no available treatment. Inflammation plays a critical role in LF progression. Glucocorticoid-induced leucine zipper (GILZ, encoded in mice by the Tsc22d3 gene) mimics many of the anti-inflammatory effects of glucocorticoids, but its role in LF has not been directly addressed. Here, we found that GILZ deficiency in mice was associated with elevated CCL2 production and pro-inflammatory leukocyte infiltration at the early LF stage, resulting in enhanced LF development. RNA interference-mediated in vivo silencing of the CCL2 receptor CCR2 abolished the increased leukocyte recruitment and the associated hepatic stellate cell activation in the livers of GILZ knockout mice. To highlight the clinical relevance of these findings, we found that TSC22D3 mRNA expression was significantly downregulated and was inversely correlated with that of CCL2 in the liver samples of patients with LF. Altogether, these data demonstrate a protective role of GILZ in LF and uncover the mechanism, which can be targeted therapeutically. Therefore, modulating GILZ expression and its downstream targets represents a novel avenue for pharmacological intervention for treating LF and possibly other liver inflammatory disorders.

Pathological Study of Facial Eczema (Pithomycotoxicosis) in Sheep

Simple Summary

Facial eczema (FE) is a secondary photosensitization disease of farm ruminants caused by the sporidesmin A, present in the spores of the saprophytic fungus Pithomyces chartarum. This study communicates an outbreak of ovine FE in Asturias (Spain) and characterizes the local immune response that may contribute to liver damage promoting cholestasis and progression towards fibrosis and cirrhosis. Animals showed clinical signs of photosensitivity and lower gain of weight, loss of wool and crusting in the head for at least 6 months after the FE outbreak. Some sheep presented acute lesions characterized by subcutaneous edema in the head, cholestasis and nephrosis with macrophages and neutrophils present in areas of canalicular cholestasis. In chronic cases, alopecia and crusting, hepatic atrophy with regenerative nodules, fibrosis and gallstones were seen. The surviving parenchyma persisted with a jigsaw pattern characteristic of biliary cirrhosis. Concentric and eccentric myointimal proliferation was found in arteries near damaged bile ducts, where macrophages and lymphocytes were also observed.

Abstract

Facial eczema (FE) is a secondary photosensitization disease of farm ruminants caused by the sporidesmin A, produced in the spores of the saprophytic fungus Pithomyces chartarum. This study communicates an outbreak of ovine FE in Asturias (Spain) and characterizes the serum biochemical pattern and the immune response that may contribute to liver damage, favoring cholestasis and the progression to fibrosis and cirrhosis. Animals showed clinical signs of photosensitivity, with decrease of daily weight gain and loss of wool and crusting for at least 6 months after the FE outbreak. Serum activity of γ-glutamyltransferase and alkaline phosphatase were significantly increased in sheep with skin lesions. In the acute phase, edematous skin lesions in the head, hepatocytic and canalicular cholestasis in centrilobular regions, presence of neutrophils in small clumps surrounding deposits of bile pigment, ductular proliferation, as well as cholemic nephrosis, were observed. Macrophages, stained positively for MAC387, were found in areas of canalicular cholestasis. In the chronic phase, areas of alopecia and crusting were seen in the head, and the liver was atrophic with large regeneration nodules and gallstones. Fibrosis around dilated bile ducts, “typical” and “atypical” ductular reaction and an inflammatory infiltrate composed of lymphocytes and pigmented macrophages, with iron deposits and lipofuscin, were found. The surviving parenchyma persisted with a jigsaw pattern characteristic of biliary cirrhosis. Concentric and eccentric myointimal proliferation was found in arteries near damaged bile ducts. In cirrhotic livers, stellated cells, ductular reaction, ectatic bile ducts and presence of M2 macrophages and lymphocytes, were observed in areas of bile ductular reaction.

Non-alcoholic fatty liver disease: An overview of risk factors, pathophysiological mechanisms, diagnostic procedures, and therapeutic interventions

Non-alcoholic fatty liver disease (NAFLD) is a disorder of excessive fat accumulation in the liver, known as steatosis, without alcohol overconsumption. NAFLD can either manifest as simple steatosis or steatohepatitis, known as non-alcoholic steatohepatitis (NASH), which is accompanied by inflammation and possibly fibrosis. Furthermore, NASH might progress to hepatocellular carcinoma. NAFLD and NASH prevalence is in a continuous state of growth, and by 2018, NAFLD became a devastating metabolic disease with a global pandemic prevalence. The pathophysiology of NAFLD and NASH is not fully elucidated, but is known to involve the complex interplay between different metabolic, environmental, and genetic factors. In addition, unhealthy dietary habits and pre-existing metabolic disturbances together with other risk factors predispose NAFLD development and progression from simple steatosis to steatohepatitis, and eventually to fibrosis. Despite their growing worldwide prevalence, to date, there is no FDA-approved treatment for NAFLD and NASH. Several off-label medications are used to target disease risk factors such as obesity and insulin resistance, and some medications are used for their hepatoprotective effects. Unfortunately, currently used medications are not sufficiently effective, and research is ongoing to investigate the beneficial effects of different drugs and phytochemicals in NASH. In this review article, we outline the different risk factors and pathophysiological mechanisms involved in NAFLD, diagnostic procedures, and currently used management techniques.

A Perspective Of Intestinal Immune-Microbiome Interactions In Alcohol-Associated Liver Disease

Uncovering the intricacies of the gut microbiome and how it interacts with the host immune system has opened up pathways in the search for the treatment of disease conditions. Alcohol-associated liver disease is a major cause of death worldwide. Research has shed light on the breakdown of the protective gut barriers, translocation of gut microbes to the liver and inflammatory immune response to microbes all contributing to alcohol-associated liver disease. This knowledge has opened up avenues for alternative therapies to alleviate alcohol-associated liver disease based on the interaction of the commensal gut microbiome as a key player in the regulation of the immune response. This review describes the relevance of the intestinal immune system, the gut microbiota, and specialized and non-specialized intestinal cells in the regulation of intestinal homeostasis. It also reflects how these components are altered during alcohol-associated liver disease and discusses new approaches for potential future therapies in alcohol-associated liver disease.

Platelet activation during chronic hepatitis B infection exacerbates liver inflammation and promotes fibrosis

Recurrent hepatitis activity during chronic hepatitis B virus infection results in fibrosis and even hepatocellular carcinoma. It is still unclear what causes acute exacerbation. As platelets have recently been identified as a significant role in inflammation, we here investigated the role of platelets in mediating liver damage in patients with chronic hepatitis B virus infection. Platelet aggregation testing and flow cytometry were carried out to evaluate platelet activation status in 121 patients chronically infected with hepatitis B across different phases of the condition. The correlation between platelet aggregation rate and liver inflammation or liver fibrosis index was evaluated. To investigate the genesis of platelet activation, several serum cytokines were also assessed by MILLIPLEX microsphere-based multiplex cytokine assay. Active hepatitis patients showed a higher aggregation rate than others. Levels of CD62p, a marker of platelet activation, were also increased in this group of patients. Positive correlations between platelet aggregation rate and liver inflammation or liver fibrosis were also noted, indicating a significant role of platelet in the progression of liver disease. The level of tumor necrosis factor-alpha, which is known to trigger platelet activation, was markedly higher in the active hepatitis group (P < .005). Based on the findings in our study, platelet activation plays a vital role in the progression of chronic hepatitis B virus infection. Antiplatelet therapy may provide a new means of hepatitis B infection treatment.

Crosstalk Between Dermal Fibroblasts and Dendritic Cells During Dengue Virus Infection

Dengue virus infection (DENV-2) is transmitted by infected mosquitoes via the skin, where many dermal and epidermal cells are potentially susceptible to infection. Most of the cells in an area of infection will establish an antiviral microenvironment to control viral replication. Although cumulative studies report permissive DENV-2 infection in dendritic cells, keratinocytes, and fibroblasts, among other cells also infected, little information is available regarding cell-to-cell crosstalk and the effect of this on the outcome of the infection. Therefore, our study focused on understanding the contribution of fibroblast and dendritic cell crosstalk to the control or promotion of dengue. Our results suggest that dendritic cells promote an antiviral state over fibroblasts by enhancing the production of type I interferon, but not proinflammatory cytokines. Infected and non-infected fibroblasts promoted partial dendritic cell maturation, and the fibroblast-matured cells were less permissive to infection and showed enhanced type I interferon production. We also observed that the soluble mediators produced by non-infected or Poly (I:C) transfected fibroblasts induced allogenic T cell proliferation, but mediators produced by DENV-2 infected fibroblasts inhibited this phenomenon. Additionally, the effects of fibroblast soluble mediators on CD14+ monocytes were analyzed to assess whether they affected the differentiation of monocyte derived dendritic cells (moDC). Our data showed that mediators produced by infected fibroblasts induced variable levels of monocyte differentiation into dendritic cells, even in the presence of recombinant GM-CSF and IL-4. Cells with dendritic cell-like morphology appeared in the culture; however, flow cytometry analysis showed that the mediators did not fully downregulate CD14 nor did they upregulate CD1a. Our data revealed that fibroblast-dendritic cell crosstalk promoted an antiviral response mediated manly by type I interferons over fibroblasts. Furthermore, the maturation of dendritic cells and T cell proliferation were promoted, which was inhibited by DENV-2-induced mediators. Together, our results suggest that activation of the adaptive immune response is influenced by the crosstalk of skin resident cells and the intensity of innate immune responses established in the microenvironment of the infected skin.

Chemerin-156 is the Active Isoform in Human Hepatic Stellate Cells

The chemokine chemerin exists as C-terminally processed isoforms whose biological functions are mostly unknown. A highly active human chemerin variant (huChem-157) was protective in experimental hepatocellular carcinoma (HCC) models. Hepatic stellate cells (HSCs) are central mediators of hepatic fibrogenesis and carcinogenesis and express the chemerin receptors chemokine-like receptor 1 (CMKLR1) and G protein-coupled receptor 1 (GPR1). Here we aimed to analyse the effect of chemerin isoforms on the viability, proliferation and secretome of the human HSC cell line LX-2. Therefore, huChem-157, 156 and 155 were over-expressed in LX-2 cells, which have low endogenous chemerin levels. HuChem-157 produced in LX-2 cells activated CMKLR1 and GPR1, and huChem-156 modestly induced GPR1 signaling. HuChem-155 is an inactive chemerin variant. Chemerin isoforms had no effect on cell viability and proliferation. Cellular expression of the fibrotic proteins galectin-3 and alpha-smooth muscle actin was not regulated by any chemerin isoform. HuChem-156 increased IL-6, IL-8 and galectin-3 in cell media. HuChem-157 was ineffective, and accordingly, did not enhance levels of these proteins in media of primary human hepatic stellate cells when added exogenously. These analyses provide evidence that huChem-156 is the biologic active chemerin variant in hepatic stellate cells and acts as a pro-inflammatory factor.

Histochemical and Immunohistochemical Characterizations of Hepatic Trematodiasis in Odontocetes

Hepatic trematodiasis is a common condition in a number of free-ranging cetacean species, which occasionally result in severe hepatic and/or pancreatic lesions. However, even the basic pathological information of this disease is unknown for the majority of affected species. The current study describes and compares the histomorphology and immune reaction induced by hepatic trematodes of the family Brachycladiidae in the liver of the harbor porpoise (Phocoena phocoena, n = 8), Dall's porpoise (Phocoenoides dalli, n = 8), and Hubbs' beaked whale (Mesoplodon carlhubbsi, n = 2). Immunohistochemistry for eight antibodies (CK19, CD3, Foxp3, CD20, Iba1, CD68, CD163, and CD204) was conducted to analyze the pathology of these parasitic infections. In all three odontocete species, the changes observed in the trematode-affected biliary epithelium were comparable with marked hyperplasia and goblet cell metaplasia, as well as lymphoplasmacytic and eosinophilic inflammation. Additionally, regions of the Glisson's sheath were diffusely and severely fibrotic in all examined species, regardless of the physical presence of trematodes. Differences among the three species included the presence of characteristic lymphoid follicles formed in the fibrotic bile duct walls of only the two porpoise species. In the Hubbs' beaked whale, the degree of lymphoplasmacytic cholangitis was more severe, and ductular reaction was generally more prominent. In terms of the overall macrophage population among the three species, CD163- and CD204-positive cells (M2 macrophages) outnumbered Iba1- and CD68-positive cells (M1 macrophages), indicating a chronic infection stage in all analyzed individuals. Species-specific differences among the infiltrating macrophages included numbers of CD68-positive cells being significantly more abundant in the harbor porpoises, whereas CD163-positive cells were significantly more numerous in the Dall's porpoises. The numbers of CD204-positive macrophages were higher in the Hubbs' beaked whales compared to those in the porpoises. Trematode species of the harbor and Dall's porpoises were Campula oblonga, while they were Oschmarinella macrorchis in the Hubbs' beaked whales. This study concludes that interspecies differences in the tissue reactions to hepatic trematode infections are present among odontocete species and that the immune reaction varies depending on the species. This information aids in furthering our understanding of the pathogenesis of hepatic trematodiasis in cetaceans.

"High Treg" Inflammations Promote (Most) Non-Hematologic Cancers While "Low Treg" Inflammations Promote Lymphoid Cancers

In an earlier publication, a binary classification of chronic diseases has been proposed. Chronic diseases were classified as “high Treg” or “low Treg” diseases depending on whether the pro-inflammatory or the anti-inflammatory arms of the immune response are deficient. The present work uses this model to analyze the interplay between cancer and the immune system, based on published literature. The work leans upon the etiology of alcohol and tobacco-related malignancies. The main conclusions are: triggers of specific “high Treg” immune reaction promote most non-hematologic cancers, whereas triggers of “low Treg” immune reaction promote lymphomas. The opposite is also true: triggers of specific “high Treg” immune reaction suppress lymphoma, whereas triggers of “low Treg” immune reaction suppress non-hematologic cancers. Both lymphoma and autoimmune diseases are “low Treg” conditions. For this reason, both are promoted by the same panel of “low Treg” bacteria and parasites and are inhibited by “high Treg” triggers. For example, alcohol consumption, a “high Treg” trigger, protects against lymphoma and autoimmune hypothyroidism. In addition, the same immune-modulatory drugs are effective in the treatment of both lymphoma and autoimmune diseases. Like other cancers, lymphoma transforms from a “low Treg” type at early stage of the disease into a “high Treg” type at advanced stages. However, lymphoma is distinguished from most other cancers by the length of time it dwells at an indolent “low Treg” state (many years) before lymphoma cells sensitivity to transforming growth factor-beta is impaired. This impairment stimulates the switch from “low Treg” into “high Treg” response and results in immune escape. The application of this analysis to the pharmacological activity of checkpoint inhibitors forecasts that checkpoint inhibitors would not be effective in low-grade, indolent lymphomas. As of now, checkpoint inhibitors are approved for the treatment of advanced lymphoma only.

Liver Fibrosis: Mechanistic Concepts and Therapeutic Perspectives

Liver fibrosis due to viral or metabolic chronic liver diseases is a major challenge of global health. Correlating with liver disease progression, fibrosis is a key factor for liver disease outcome and risk of hepatocellular carcinoma (HCC). Despite different mechanism of primary liver injury and disease-specific cell responses, the progression of fibrotic liver disease follows shared patterns across the main liver disease etiologies. Scientific discoveries within the last decade have transformed the understanding of the mechanisms of liver fibrosis. Removal or elimination of the causative agent such as control or cure of viral infection has shown that liver fibrosis is reversible. However, reversal often occurs too slowly or too infrequent to avoid life-threatening complications particularly in advanced fibrosis. Thus, there is a huge unmet medical need for anti-fibrotic therapies to prevent liver disease progression and HCC development. However, while many anti-fibrotic candidate agents have shown robust effects in experimental animal models, their anti-fibrotic effects in clinical trials have been limited or absent. Thus, no approved therapy exists for liver fibrosis. In this review we summarize cellular drivers and molecular mechanisms of fibrogenesis in chronic liver diseases and discuss their impact for the development of urgently needed anti-fibrotic therapies.

Bone morphogenetic protein 4 provides cancer-supportive phenotypes to liver fibroblasts in patients with hepatocellular carcinoma

BACKGROUND

Cancer-associated fibroblasts (CAFs) are essential constituents of cancer-supportive microenvironments. The high incidence of hepatocellular carcinoma (HCC) in advanced fibrosis patients implies that fibroblasts have a promoting effect on HCC development. We aimed to explore the regulators of phenotypes and function of CAFs in the liver.

METHODS

We established primary cancer-associated fibroblasts (CAFs) and non-cancerous liver fibroblasts (NFs) from 15 patients who underwent HCC resection. We compared phenotypes, capacity of cytokine/chemokine production and gene expression profiles between pairs of CAFs and NFs from the same donors. We examined resected tissue from additional 50 patients with HCC for immunohistochemical analyses.

RESULTS

The CAFs expressed more ACTA2 and COL1A1 than the NFs, suggesting that CAFs are more activated phenotype. The CAFs produced larger amounts of IL-6, IL-8 and CCL2 than the NFs, which led to invasiveness of HuH7 in vitro. We found that Bone Morphogenetic Protein-4 (BMP4) is up-regulated in CAFs compared to NFs. The CAF phenotype and function were gained by BMP4 over-expression or recombinant BMP4 given to fibroblasts, all of which decreased with BMP4 knockdown. In tissues obtained from the patients, BMP4-positive cells are mainly observed in encapsulated fibrous lesions and HCC. Positive expression of BMP4 in HCC in resected tissues, not in fibroblasts, was associated with poorer postoperative overall survival in patients with HCC.

CONCLUSION

Endogenous and exogenous BMP4 activate liver fibroblasts to gain capacity of secreting cytokines and enhancing invasiveness of cancer cells in the liver. BMP4 is one of the regulatory factors of CAFs functioning in the microenvironment of HCC.

Perilipin-2 promotes obesity and progressive fatty liver disease in mice through mechanistically distinct hepatocyte and extra-hepatocyte actions

KEY POINTS

Wild-type mice and mice with hepatocyte-specific or whole-body deletions of perilipin-2 (Plin2) were used to define hepatocyte and extra-hepatocyte effects of altered cellular lipid storage on obesity and non-alcoholic fatty liver disease (NAFLD) pathophysiology in a Western-diet (WD) model of these disorders. Extra-hepatocyte actions of Plin2 are responsible for obesity, adipose inflammation and glucose clearance abnormalities in WD-fed mice. Hepatocyte and extra-hepatic actions of Plin2 mediate fatty liver formation in WD-fed mice through distinct mechanisms. Hepatocyte-specific actions of Plin2 are primary mediators of immune cell infiltration and fibrotic injury in livers of obese mice.

ABSTRACT

Non-alcoholic fatty liver disease (NAFLD) is an obesity- and insulin resistance-related metabolic disorder with progressive pathology. Perilipin-2 (Plin2), a ubiquitously expressed cytoplasmic lipid droplet scaffolding protein, is hypothesized to contribute to NAFLD in humans and rodent models through effects on cellular lipid metabolism. In this study, we delineate hepatocyte-specific and extra-hepatocyte Plin2 mechanisms regulating the effects of obesity and insulin resistance on NAFLD pathophysiology in mice fed an obesogenic Western-style diet (WD). Total Plin2 deletion (Plin2-Null) fully protected WD-fed mice from obesity, insulin resistance, adipose inflammation, steatohepatitis (NASH) and liver fibrosis found in WT animals. Hepatocyte-specific Plin2 deletion (Plin2-HepKO) largely protected against NASH and fibrosis and partially protected against steatosis in WD-fed animals, but it did not protect against obesity, insulin resistance, or adipose inflammation. Significantly, total or hepatocyte-specific Plin2 deletion impaired WD-induced monocyte recruitment and pro-inflammatory macrophage polarization found in livers of WT mice. Analyses of the molecular and cellular processes mediating steatosis, inflammation and fibrosis identified differences in total and hepatocyte-specific actions of Plin2 on the mechanisms promoting NAFLD pathophysiology. Our results demonstrate that hepatocyte-specific actions of Plin2 are central to the initiation and pathological progression of NAFLD in obese and insulin-resistant mice through effects on immune cell recruitment and fibrogenesis. Conversely, extra-hepatocyte Plin2 actions promote NAFLD pathophysiology through effects on obesity, inflammation and insulin resistance. Our findings provide new insight into hepatocyte and extra-hepatocyte mechanisms underlying NAFLD development and progression.

Molecular mechanisms in the pathogenesis of N-nitrosodimethylamine induced hepatic fibrosis

Hepatic fibrosis is marked by excessive synthesis and deposition of connective tissue proteins, especially interstitial collagens in the extracellular matrix of the liver. It is a result of an abnormal wound healing in response to chronic liver injury from various causes such as ethanol, viruses, toxins, drugs, or cholestasis. The chronic stimuli involved in the initiation of fibrosis leads to oxidative stress and generation of reactive oxygen species that serve as mediators of molecular events involved in the pathogenesis of hepatic fibrosis. These processes lead to cellular injury and initiate inflammatory responses releasing a variety of cytokines and growth factors that trigger activation and transformation of resting hepatic stellate cells into myofibroblast like cells, which in turn start excessive synthesis of connective tissue proteins, especially collagens. Uncontrolled and extensive fibrosis results in distortion of lobular architecture of the liver leading to nodular formation and cirrhosis. The perpetual injury and regeneration process could also results in genomic aberrations and mutations that lead to the development of hepatocellular carcinoma. This review covers most aspects of the molecular mechanisms involved in the pathogenesis of hepatic fibrosis with special emphasize on N-Nitrosodimethylamine (NDMA; Dimethylnitorsmaine, DMN) as the inducing agent.

Doxazosin and Carvedilol Treatment Improves Hepatic Regeneration in a Hamster Model of Cirrhosis

Regulation of the mechanisms of fibrosis is an important goal in the treatment of liver cirrhosis. One mechanism is the participation of hepatic stellate cells in fibrogenesis when activated by catecholamines. Consequently, α/β adrenoblockers are proposed as an alternative treatment for chronic liver lesions such as fibrosis and/or cirrhosis and for possible liver regeneration. We herein analyzed the effect of doxazosin and carvedilol treatments during the regeneration of tissue in a hamster model of liver cirrhosis. Tissue samples were examined by H&E and PAS to evaluate tissue damage and with Sirius red to assess collagen fiber content. ALT, AST, albumin, and total proteins were examined by spectrophotometry. Determination of the levels of α-SMA and TGF-β in hepatic tissue was examined by Western blot and of the expression of TIMP-2, MMP-13, α-FP, HGF, CK-7, and c-Myc was examined by qPCR. Treatment with doxazosin or carvedilol prompted histological recovery and reduced collagen fibers in the livers of cirrhotic hamsters. The expression of TIMP-2 decreased and that of MMP-13 increases in animals treated with adrenoblockers with respect to the group with cirrhosis. Additionally, the concentration of α-SMA and TGF-β declined with both drugs with respect to placebo p<0.05. On the other hand, each drug treatment led to a distinct scenario for cell proliferation markers. Whereas doxazosin produced no irregularities in α-FP, Ki-67, and c-Myc expression, carvedilol induced an increment in the expression of these markers with respect to the intact. Hence, doxazosin and carvedilol are potential treatments for the regression of hepatic cirrhosis in hamsters in relation to the decrease of collagen in the hepatic parenchyma. However, at regeneration level we observed that doxazosin caused slight morphological changes in hepatocytes, such as its balonization without affecting the hepatic function, and on the other hand, carvedilol elicited a slight irregular expression of cell proliferation markers.

Hepatoprotective Principles and Other Chemical Constituents from the Mycelium of Phellinus linteus

In the dimethylnitrosamine (DMN)-induced hepatic fibrosis Wistar rat model, the mycelium extract of Phellinus linteus (PLE) (20 mg/Kg) displayed significant protection against hepatic fibrosis. The present investigation characterized eleven new ionone derivatives, phellinulins D–N (4–14), from the P. linteus mycelium extract and the relative stereochemical structures were constructed according to the spectroscopic and spectrometric analytical results. Some purified compounds were examined for their inhibitory effects on activated rat hepatic stellate cells (HSCs) and several isolates did exhibit significant protection. The results indicated that the mycelium of P. linteus could be explored as a hepatoprotective drug or healthy food candidate in the near future.

[The Progression of Liver Fibrosis in Non-alcoholic Fatty Liver Disease]

Understanding the pathogenesis of non-alcoholic steatohepatitis (NASH) and its fibrosis progression is still evolving. Nonetheless, current evidence suggests that mechanisms involved are very complex parallel processes with multiple metabolic factors. Lipotoxicity related with excess saturated free fatty acids, obesity, and insulin resistance acts as the central driver of cellular injury via oxidative stress. Hepatocyte apoptosis and/or senescence are also contribute to the activation of inflammasome via various intra- and inter-cellular signaling mechanisms that lead to fibrosis. Current evidence suggests that periportal components, including ductular reaction and expansion of the hepatic progenitor cell compartment, may be involved and that the T-helper 17 cell response may mediate disease progression. This review aims to provide a brief overview of the pathogenesis of NASH and fibrosis progression from inflammation to fibrosis.

New insights into Nod-like receptors (NLRs) in liver diseases

Activation of inflammatory signaling pathways is of central importance in the pathogenesis of alcoholic liver disease (ALD) and nonalcoholic steatohepatitis (NASH). Nod-like receptors (NLRs) are intracellular innate immune sensors of microbes and danger signals that control multiple aspects of inflammatory responses. Recent studies demonstrated that NLRs are expressed and activated in innate immune cells as well as in parenchymal cells in the liver. For example, NLRP3 signaling is involved in liver ischemia-reperfusion (I/R) injury and silencing of NLRP3 can protect the liver from I/R injury. In this article, we review the evidence that highlights the critical importance of NLRs in the prevalent liver diseases. The significance of NLR-induced intracellular signaling pathways and cytokine production is also evaluated.

Up-regulation of Interleukin-21 Contributes to Liver Pathology of Schistosomiasis by Driving GC Immune Responses and Activating HSCs in Mice

The pathology of schistosome egg-induced liver granuloma, fibrosis and eventually liver scarring is complicated. CD4⁺ helper T (Th) cells play critical roles in both host humoral immunity and cellular immunity against parasitic infection and immunopathology in schistosomiasis. Follicular helper T (Tfh) cells are another specialized subset of Th cells and involved in infectious diseases. However, the immune regulatory mechanism of Tfh cells in severe liver pathology of schistosomiasis is still poorly understood. In this study, using a S. japonicum-infected mouse model, we studied the dynamics and effects of Tfh cells in vivo and demonstrated that Tfh phenotype molecules ICOS, PD-1 and functional factor IL-21 were positively correlated with disease development by flow cytometry. Meanwhile, our results also showed that Tfh cells enriched in splenic germinal center (GC) and promoted B cells producing IgM with the progress of hepatic immunopathology by B-T co-culture experiments. More importantly, our data indicated that IL-21 contributed to the formation and development of hepatic egg granuloma and subsequent fibrosis by driving GC responses and activating HSCs by immunohistochemical detection and blocking assay in vitro. Our findings contribute to the better understanding of the immunopathogenesis of schistosomiasis and have implications for therapeutic intervention of hepatic fibrotic diseases.

The Injury-Related Activation of Hedgehog Signaling Pathway Modulates the Repair-Associated Inflammation in Liver Fibrosis

Liver fibrosis is a wound healing response initiated by inflammation responding for different iterative parenchymal damages caused by diverse etiologies. Immune cells, which exert their ability of either inducing injury or promoting repair, have been regarded as crucial participants in the fibrogenic response. A characteristic feature of the fibrotic microenvironment associated with chronic liver injury is aberrant activation of hedgehog (Hh) signaling pathway. Growing evidence from a number of different studies in vivo and in vitro has indicated that immune-mediated events involved in liver fibrogenesis are regulated by Hh signaling pathway. In this review, we emphasize the impacts of injury-activated Hh signaling on liver fibrogenesis through modulating repair-related inflammation and focus on the regulatory action of aberrant Hh signaling on repair-related inflammatory responses mediated by hepatic classical and non-classical immune cell populations in the progression of liver fibrosis. Moreover, we also assess the potentiality of Hh pathway inhibitors as good candidates for anti-fibrotic therapeutic agents because of their immune regulation actions for fibrogenic liver repair. The identification of immune-modulatory mechanisms of Hh signaling pathway underlying the fibrotic process of chronic liver diseases might provide a basis for Hh-centered therapeutic strategies for liver fibrosis.

Liver cirrhosis reversion is improved in hamsters with a neurointermediate pituitary lobectomy

Regulating mechanisms of fibrosis is an important goal in the treatment of fibrosis and liver cirrhosis. The role of arginine vasopressin (AVP) in promoting fibrosis in several organs has been well documented. However, the result of an AVP deficiency during liver fibrosis has not been reported. We herein study the effects of an AVP deficiency, which was induced by neurointermediate pituitary lobectomy (NIL), on liver cirrhosis and liver cirrhosis reversion. Hamsters were intact (control) or underwent CCl₄-induced cirrhosis, the latter animals divided into four groups: Cirrhotic, NIL-cirrhotic, Cirrhotic-reversion (R) and NIL-cirrhotic-R. Liver function, liver histopathology (including the fibrosis area and collagen types) and liver expression of MMP-13 and TIMP-2 were assessed. Results show that the AVP deficiency decreased the levels of alkaline phosphatase in serum and the expression of type I collagen and TIMP-2, and increased type III collagen deposition, MMP-13 expression and the size of regeneration nodules in NIL-cirrhotic and NIL-cirrhotic-R animals. A significantly greater recovery was found in the NIL-cirrhotic-R than the Cirrhotic-R group. We conclude that an AVP deficiency participates importantly in hamster liver regeneration by: 1) prompting the fibroblasts to produce type III collagen deposit, 2) influencing the activity of AP from bile duct cells, and 3) inhibiting TIMP-2 expression while favoring the fibrolytic activity of MMP-13.

Coding and non-coding gene regulatory networks underlie the immune response in liver cirrhosis

Liver cirrhosis is recognized as being the consequence of immune-mediated hepatocyte damage and repair processes. However, the regulation of these immune responses underlying liver cirrhosis has not been elucidated. In this study, we used GEO datasets and bioinformatics methods to established coding and non-coding gene regulatory networks including transcription factor-/lncRNA-microRNA-mRNA, and competing endogenous RNA interaction networks. Our results identified 2224 mRNAs, 70 lncRNAs and 46 microRNAs were differentially expressed in liver cirrhosis. The transcription factor -/lncRNA- microRNA-mRNA network we uncovered that results in immune-mediated liver cirrhosis is comprised of 5 core microRNAs (e.g., miR-203; miR-219-5p), 3 transcription factors (i.e., FOXP3, ETS1 and FOS) and 7 lncRNAs (e.g., ENTS00000671336, ENST00000575137). The competing endogenous RNA interaction network we identified includes a complex immune response regulatory subnetwork that controls the entire liver cirrhosis network. Additionally, we found 10 overlapping GO terms shared by both liver cirrhosis and hepatocellular carcinoma including “immune response” as well. Interestingly, the overlapping differentially expressed genes in liver cirrhosis and hepatocellular carcinoma were enriched in immune response-related functional terms. In summary, a complex gene regulatory network underlying immune response processes may play an important role in the development and progression of liver cirrhosis, and its development into hepatocellular carcinoma.

Platelets: No longer bystanders in liver disease

Growing lines of evidence recognize that platelets play a central role in liver homeostasis and pathobiology. Platelets have important roles at every stage during the continuum of liver injury and healing. These cells contribute to the initiation of liver inflammation by promoting leukocyte recruitment through sinusoidal endothelium. They can activate effector cells, thus amplifying liver damage, and by modifying the hepatic cellular and cytokine milieu drive both hepatoprotective and hepatotoxic processes.

CONCLUSION

In this review we summarize how platelets drive such pleiotropic actions and attempt to reconcile the paradox of platelets being both deleterious and beneficial to liver function; with increasingly novel methods of manipulating platelet function at our disposal, we highlight avenues for future therapeutic intervention in liver disease. (Hepatology 2016;64:1774-1784).

Doxazosin Treatment Attenuates Carbon Tetrachloride-Induced Liver Fibrosis in Hamsters through a Decrease in Transforming Growth Factor β Secretion

Background/Aims

The development of therapeutic strategies for the treatment of cirrhosis has become an important focus for basic and clinical researchers. Adrenergic receptor antagonists have been evaluated as antifibrotic drugs in rodent models of carbon tetrachloride (CCl4)-induced cirrhosis. The aim of the present study was to evaluate the effects of carvedilol and doxazosin on fibrosis/cirrhosis in a hamster animal model.

Methods

Cirrhotic-induced hamsters were treated by daily administration of carvedilol and doxazosin for 6 weeks. Hepatic function and histological evaluation were conducted by measuring biochemical markers, including total bilirubin, aspartate aminotransferase, alanine aminotransferase and albumin, and liver tissue slices. Additionally, transforming growth factor β (TGF-β) immunohistochemistry was analyzed.

Results

Biochemical markers revealed that hepatic function was restored after treatment with doxazosin and carvedilol. Histological evaluation showed a decrease in collagen type I deposits and TGF-β-secreting cells.

Conclusions

Taken together, these results suggest that the decrease in collagen type I following treatment with doxazosin or carvedilol is achieved by decreasing the profibrotic activities of TGF-β via the blockage of α1- and β-adrenergic receptor. Consequently, a diminution of fibrotic tissue in the CCl4-induced model of cirrhosis is achieved.

Ionone Derivatives from the Mycelium of Phellinus linteus and the Inhibitory Effect on Activated Rat Hepatic Stellate Cells

Three new γ-ionylideneacetic acid derivatives, phellinulins A-C (1-3), were characterized from the mycelium extract of Phellinus linteus. The chemical structures were established based on the spectroscopic analysis. In addition, phellinulin A (1) was subjected to the examination of effects on activated rat hepatic stellate cells and exhibited significant inhibition of hepatic fibrosis.

Pathobiochemical signatures of cholestatic liver disease in bile duct ligated mice

Background

Disrupted bile secretion leads to liver damage characterized by inflammation, fibrosis, eventually cirrhosis, and hepatocellular cancer. As obstructive cholestasis often progresses insidiously, markers for the diagnosis and staging of the disease are urgently needed. To this end, we compiled a comprehensive data set of serum markers, histological parameters and transcript profiles at 8 time points of disease progression after bile duct ligation (BDL) in mice, aiming at identifying a set of parameters that could be used as robust biomarkers for transition of different disease progression phases.

Results

Statistical analysis of the more than 6,000 data points revealed distinct temporal phases of disease. Time course correlation analysis of biochemical, histochemical and mRNA transcript parameters (=factors) defined 6 clusters for different phases of disease progression. The number of CTGF-positive cells provided the most reliable overall measure for disease progression at histological level, bilirubin at biochemical level, and metalloproteinase inhibitor 1 (Timp1) at transcript level. Prominent molecular events exhibited by strong transcript peaks are found for the transcriptional regulator Nr0b2 (Shp) and 1,25-dihydroxyvitamin D(3) 24-hydroxylase (Cyp24a1) at 6 h. Based on these clusters, we constructed a decision tree of factor combinations potentially useful as markers for different time intervals of disease progression. Best prediction for onset of disease is achieved by fibronectin (Fn1), for early disease phase by Cytochrome P450 1A2 (Cyp1a2), passage to perpetuation phase by collagen1α-1 (Col1a1), and transition to the progression phase by interleukin 17-a (Il17a), with early and late progression separated by Col1a1. Notably, these predictions remained stable even for randomly chosen small sub-sets of factors selected from the clusters.

Conclusion

Our detailed time-resolved explorative study of liver homogenates following BDL revealed a well-coordinated response, resulting in disease phase dependent parameter modulations at morphological, biochemical, metabolic and gene expression levels. Interestingly, a small set of selected parameters can be used as diagnostic markers to predict disease stages in mice with cholestatic liver disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-015-0229-0) contains supplementary material, which is available to authorized users.

Osteopontin neutralisation abrogates the liver progenitor cell response and fibrogenesis in mice

BACKGROUND

Chronic liver injury triggers a progenitor cell repair response, and liver fibrosis occurs when repair becomes deregulated. Previously, we reported that reactivation of the hedgehog pathway promotes fibrogenic liver repair. Osteopontin (OPN) is a hedgehog-target, and a cytokine that is highly upregulated in fibrotic tissues, and regulates stem-cell fate. Thus, we hypothesised that OPN may modulate liver progenitor cell response, and thereby, modulate fibrotic outcomes. We further evaluated the impact of OPN-neutralisation on murine liver fibrosis.

METHODS

Liver progenitors (603B and bipotential mouse oval liver) were treated with OPN-neutralising aptamers in the presence or absence of transforming growth factor (TGF)-β, to determine if (and how) OPN modulates liver progenitor function. Effects of OPN-neutralisation (using OPN-aptamers or OPN-neutralising antibodies) on liver progenitor cell response and fibrogenesis were assessed in three models of liver fibrosis (carbon tetrachloride, methionine-choline deficient diet, 3,5,-diethoxycarbonyl-1,4-dihydrocollidine diet) by quantitative real time (qRT) PCR, Sirius-Red staining, hydroxyproline assay, and semiquantitative double-immunohistochemistry. Finally, OPN expression and liver progenitor response were corroborated in liver tissues obtained from patients with chronic liver disease.

RESULTS

OPN is overexpressed by liver progenitors in humans and mice. In cultured progenitors, OPN enhances viability and wound healing by modulating TGF-β signalling. In vivo, OPN-neutralisation attenuates the liver progenitor cell response, reverses epithelial-mesenchymal-transition in Sox9+ cells, and abrogates liver fibrogenesis.

CONCLUSIONS

OPN upregulation during liver injury is a conserved repair response, and influences liver progenitor cell function. OPN-neutralisation abrogates the liver progenitor cell response and fibrogenesis in mouse models of liver fibrosis.

Activated rat hepatic stellate cells influence Th1/Th2 profile in vitro

AIM: To investigate the effects of activated rat hepatic stellate cells (HSCs) on rat Th1/Th2 profile in vitro.

METHODS: Growth and survival of activated HSCs and CD4⁺ T lymphocytes cultured alone or together was assessed after 24 or 48 h. CD4⁺ T lymphocytes were then cultured with or without activated HSCs for 24 or 48 h and the proportion of Th1 [interferon (IFN)-γ⁺] and Th2 [interleukin (IL)-4⁺] cells was assessed by flow cytometry. Th1 and Th2 cell apoptosis was assessed after 24 h of co-culture using a caspase-3 staining procedure. Differentiation rates of Th1 and Th2 cells from CD4⁺ T lymphocytes that were positive for CD25 but did not express IFN-γ or IL-4 were also assessed after 48 h of co-culture with activated HSCs. Galectin-9 expression in HSCs was determined by immunofluorescence and Western blotting. ELISA was performed to assess galectin-9 secretion from activated HSCs.

RESULTS: Co-culture of CD4⁺ T lymphocytes with activated rat HSCs for 48 h significantly reduced the proportion of Th1 cells compared to culture-alone conditions (-1.73% ± 0.71%; P < 0.05), whereas the proportion of Th2 cells was not altered; the Th1/Th2 ratio was significantly decreased (-0.44 ± 0.13; P < 0.05). In addition, the level of IFN-γ in Th1 cells was decreased (-65.71 ± 9.67; P < 0.01), whereas the level of IL-4 in Th2 cells was increased (82.79 ± 25.12; P < 0.05) by co-culturing, as measured by mean fluorescence intensity by flow cytometry. Apoptosis rates in Th1 (12.27% ± 0.99%; P < 0.01) and Th2 (1.71% ± 0.185%; P < 0.01) cells were increased 24 h after co-culturing with activated HSCs; the Th1 cell apoptosis rate was significantly higher than in Th2 cells (P < 0.01). Galectin-9 protein expression was significantly decreased in HSCs only 24 h after co-culturing (P < 0.05) but not after 48 h. Co-culture for 48 h significantly increased the differentiation of Th1 and Th2 cells; however, the increase in the proportion of Th2 cells was significantly higher than that of Th1 cells (1.85% ± 0.48%; P < 0.05).

CONCLUSION: Activated rat HSCs lower the Th1/Th2 profile, inhibiting the Th1 response and enhancing the Th2 response, and this may be a novel pathway for liver fibrogenesis.

Interleukin-22 ameliorates liver fibrogenesis by attenuating hepatic stellate cell activation and downregulating the levels of inflammatory cytokines

AIM

To investigate the effect of interleukin (IL)-22 on hepatic fibrosis in mice and the possible mechanism involved.

METHODS

Liver fibrosis was induced in male BALB/c mice by CCl₄. Recombinant IL-22 (rmIL-22) was administered intraperitoneally in CCl₄-treated mice. Fibrosis was assessed by histology and Masson staining. The activation of hepatic stellate cells (HSCs) was investigated by analysis of α-smooth muscle actin expression. The frequencies of T helper (Th) 22 cells, Th17 cells and Th1 cells, the expression of inflammatory cytokines [IL-22, IL-17A, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), IL-6, IL-1β] and transcription factors [aryl hydrocarbon receptor (AHR), RAR-related orphan receptor (RORγt), T-bet] mRNA in the liver were investigated. In addition, the plasma levels of IL-22, IL-17A, IFN-γ, TNF-α, IL-6 and IL-1β were evaluated.

RESULTS

Significant elevations in circulating Th22 cells, Th17 cells, Th1 cells, IL-22, IL-17A, and IFN-γ were observed in the hepatic fibrosis group compared with the control group (P < 0.01). Treatment with rmIL-22 in mice with hepatic fibrosis ameliorated the severity of hepatic fibrosis, which was confirmed by lower hepatic fibrosis pathological scores (P < 0.01). RmIL-22 decreased the frequencies of Th22 cells (6.71% ± 0.97% vs 8.09% ± 0.74%, P < 0.01), Th17 cells (4.34% ± 0.37% vs 5.71% ± 0.24%, P < 0.01), Th1 cells (3.09% ± 0.49% vs 4.91% ± 0.73%, P < 0.01), and the levels of IL-22 (56.23 ± 3.08 vs 70.29 ± 3.01, P < 0.01), IL-17A (30.74 ± 2.77 vs 45.68 ± 2.71, P < 0.01), and IFN-γ (74.78 ± 2.61 vs 124.89 ± 2.82, P < 0.01). Down-regulation of IL-22, IL-17A, IFN-γ, TNF-α, IL-6, IL-1β, AHR RORγt, and T-bet gene expression in the liver was observed in the rmIL-22 group (P < 0.01).

CONCLUSION

The frequencies of Th22, Th17 and Th1 cells are elevated in hepatic fibrosis. RmIL-22 can attenuate HSC activation and down-regulate the levels of inflammatory cytokines, thereby ameliorating liver fibrogenesis.

Th17 down-regulation is involved in reduced progression of schistosomiasis fibrosis in ICOSL KO mice

Background

Granulomatous and fibrosing inflammation in response to parasite eggs is the main pathology that occurs during infection with Schistosoma spp. CD4+ T cells play critical roles in both host immune responses against parasitic infection and immunopathology in schistosomiasis,and coordinate many types of immune cells that contribute to fibrosis. ICOSL plays an important role in controlling specific aspects of T cell activation, differentiation, and function. Previous work has suggested that ICOS is essential for Th17 cell development. However, the immunopathogenesis of this pathway in schistosomiasis fibrosisis still unclear.

Methodology/Principal Findings

Using models of schistosomiasis in ICOSL KO and the C57BL/6 WT mice, we studied the role of the ICOSL/ICOS interaction in the mediation of the Th17 response in host granulomatous inflammation, particularly in liver fibrosis during S. japonicum infection, and investigated the immune responses and pathology of ICOSL KO mice in these models. The results showed that ICOSL KO mice exhibited improved survival, reduced liver granulomatous inflammation around parasite eggs, markedly inhibited hepatic fibrosis development, lower levels of Th17-related cytokines (IL-17/IL-21), Th2-related cytokines (IL-4/IL-6/IL-10), a pro-fibrotic cytokine (IL-13), and TGF-β1, but higher level of Th1-related cytokine (IFN-γ) compared to wild-type (WT) mice. The reduced progression of fibrogenesis was correlated with the down-regulation of Th17 and Th2 and the elimination of ICOSL/ICOS interactions.

Conclusions/Significance

Our findings suggest that IL-17-producing cells contribute to the hepatic granulomatous inflammation and subsequent fibrosis. Importantly, there was a clearly positive correlation between the presence of IL-17-producing cells and ICOS expression in ICOSL KO mice, and additional results indicated that Th17 was involved in the pathological tissue remodeling in liver fibrosis induced by schistosomiasis.

The full activation and differentiation of T cells into Th1, Th2 or Th17 cells requires costimulatory molecules and cytokines. ICOS has also been implicated in chronic inflammation and is critical for Th17 cell development. CD4⁺ IL-17-secreting T cells have been shown to contribute to pathology in some models of liver fibrosis. However, neither the significance nor the immunopathogenesis of this pathway have been elucidated in schistosomiasis fibrosis. The present study used the ICOSL KO mice to assess the role of the ICOSL/ICOS interaction in the mediation of the Th17 response in host granulomatous inflammation, particularly in liver fibrosis during S.japonicum infection. This study further clarifies the immune regulatory mechanism of fibrosis and sheds light on the understanding of the immunopathogenesis of Schistosoma-induced fibrosis. It might reveal new therapeutic targets that interfere with Th17 cell migration or differentiation in granulomas and the subsequent fibrosis following infection with S. japonicum.

Evolving concepts in the pathogenesis of NASH: beyond steatosis and inflammation

Non-alcoholic steatohepatitis (NASH) is characterised by hepatic steatosis and inflammation and, in some patients, progressive fibrosis leading to cirrhosis. An understanding of the pathogenesis of NASH is still evolving but current evidence suggests multiple metabolic factors critically disrupt homeostasis and induce an inflammatory cascade and ensuing fibrosis. The mechanisms underlying these changes and the complex inter-cellular interactions that mediate fibrogenesis are yet to be fully elucidated. Lipotoxicity, in the setting of excess free fatty acids, obesity, and insulin resistance, appears to be the central driver of cellular injury via oxidative stress. Hepatocyte apoptosis and/or senescence contribute to activation of the inflammasome via a variety of intra- and inter-cellular signalling mechanisms leading to fibrosis. Current evidence suggests that periportal components, including the ductular reaction and expansion of the hepatic progenitor cell compartment, may be involved and that the Th17 response may mediate disease progression. This review aims to provide an overview of the pathogenesis of NASH and summarises the evidence pertaining to key mechanisms implicated in the transition from steatosis and inflammation to fibrosis. Currently there are limited treatments for NASH although an increasing understanding of its pathogenesis will likely improve the development and use of interventions in the future.

Inhibition of TNF-α-Mediated NF-κB Transcriptional Activity by Dammarane-Type Ginsenosides from Steamed Flower Buds of Panax ginseng in HepG2 and SK-Hep1 Cells

Panax ginseng is a medicinal herb that is used worldwide. Its medicinal effects are primarily attributable to ginsenosides located in the root, leaf, seed, and flower. The flower buds of Panax ginseng (FBPG) are rich in various bioactive ginsenosides, which exert immunomodulatory and anti-inflammatory activities. The aim of the present study was to assess the effect of 18 ginsenosides isolated from steamed FBPG on the transcriptional activity of NF-κB and the expression of tumor necrosis factor-α (TNF-α)-stimulated target genes in liver-derived cell lines. Noticeably, the ginsenosides Rk₃ and Rs₄ exerted the strongest activity, inhibiting NF-κB in a dose-dependent manner. SF and Rg₆ also showed moderately inhibitory effects. Furthermore, these four compounds inhibited the TNF-α-induced expression of IL8, CXCL1, iNOS, and ICAM1 genes. Consequently, ginsenosides purified from steamed FBPG have therapeutic potential in TNF-α-mediated diseases such as chronic hepatic inflammation.

Cannabinoid receptor 2 counteracts interleukin-17-induced immune and fibrogenic responses in mouse liver

Interleukin (IL)-17 is a proinflammatory and fibrogenic cytokine mainly produced by T-helper (Th)17 lymphocytes, together with the hepatoprotective and antifibrogenic cytokine, IL-22. Cannabinoid receptor 2 (CB2) is predominantly expressed in immune cells and displays anti-inflammatory and antifibrogenic effects. In the present study, we further investigated the mechanism underlying antifibrogenic properties of CB2 receptor and explored its effect on the profibrogenic properties of IL-17. After bile duct ligation (BDL), the hepatic expression of Th17 markers and IL-17 production were enhanced in CB2(-/-) mice, as compared to wild-type (WT) counterparts, and correlated with increased fibrosis in these animals. In contrast, IL-22-induced expression was similar in both animal groups. Inhibition of Th17 differentiation by digoxin lowered Th17 marker gene expression and IL-17 production and strongly reduced liver fibrosis in CB2(-/-) BDL mice. In vitro, differentiation of CD4(+) naïve T cells into Th17 lymphocytes was decreased by the CB2 agonist, JWH-133, and was associated with reduced Th17 marker messenger RNA expression and IL-17 production, without modification of IL-22 release. The inhibitory effect of JWH-133 on IL-17 production relied on signal transducer and activator of transcription (STAT)5 phosphorylation. Indeed, STAT5 phosphorylation and translocation into the nucleus was enhanced in JWH133-treated Th17 lymphocytes, and the addition of a STAT5 inhibitor reversed the inhibitory effect of the CB2 agonist on IL-17 production, without affecting IL-22 levels. Finally, in vitro studies also demonstrated that CB2 receptor activation in macrophages and hepatic myofibroblasts blunts IL-17-induced proinflammatory gene expression.

CONCLUSION

These data demonstrate that CB2 receptor activation decreases liver fibrosis by selectively reducing IL-17 production by Th17 lymphocytes via a STAT5-dependent pathway, and by blunting the proinflammatory effects of IL-17 on its target cells, while preserving IL-22 production.

Liver Injury and the Activation of the Hepatic Myofibroblasts

Liver fibrosis is a wound healing process, the end result of chronic liver injury elicited by different noxious stimuli. Activated hepatic stellate cells or myofibroblasts and portal myofibroblasts are considered as the main producers of the extracellular matrix in the liver. Upon liver injury the quiescent stellate cells transdifferentiate into myofibroblasts a process highlighted by the loss of vitamin A stores, upregulation of interstitial type collagens, smooth muscle α actin, matrix metalloproteinases, proteoglycans, and the induction of cell survival pathways. Activation of hepatic stellate cells is a result of a complex interplay between the parenchymal cells, immune cells, extracellular matrix mechanics and extrahepatic milieu such as the gut microbiome. In this review we will focus on the pathomechanism of stellate cell activation following chronic liver injury; with the aim of identifying possible treatment targets for anti-fibrogenic agents.

The chemokine CCL3 promotes experimental liver fibrosis in mice

Liver fibrosis is associated with infiltrating immune cells and activation of hepatic stellate cells. We here aimed to investigate the effects of the CC chemokine CCL3, also known as macrophage inflammatory protein-1α, in two different fibrosis models. To this end, we treated mice either with carbon tetrachloride or with a methionine- and choline-deficient diet to induce fibrosis in CCL3 deficient and wild-type mice. The results show that the protein expression of CCL3 is increased in wild-type mice after chronic liver injury. Deletion of CCL3 exhibited reduced liver fibrosis compared to their wild-type counterparts. We could validate these results by treating the two mouse groups with either carbon tetrachloride or by feeding a methionine- and choline-deficient diet. In these models, lack of CCL3 is functionally associated with reduced stellate cell activation and liver immune cell infiltration. In vitro, we show that CCL3 leads to increased proliferation and migration of hepatic stellate cells. In conclusion, our results define the chemokine CCL3 as a mediator of experimental liver fibrosis. Thus, therapeutic modulation of CCL3 might be a promising target for chronic liver diseases.