Infection of Human Liver Myofibroblasts by Hepatitis C Virus: A Direct Mechanism of Liver Fibrosis in Hepatitis C

Tight Junction Proteins as Therapeutic Targets to Treat Liver Fibrosis and Hepatocellular Carcinoma

In the last decade tight junction proteins exposed at the surface of liver or cancer cells have been uncovered as mediators of liver disease biology: Claudin-1 and Occludin are host factors for hepatitis C virus entry and Claudin-1 has been identified as a driver for liver fibrosis and hepatocellular carcinoma (HCC). Moreover, Claudins have emerged as therapeutic targets for liver disease and HCC. CLDN1 expression is upregulated in liver fibrosis and HCC. Monoclonal antibodies (mAbs) targeting Claudin-1 have completed preclinical proof-of-concept studies for treatment of liver fibrosis and HCC and are currently in clinical development for advanced liver fibrosis. Claudin-6 overexpression is associated with an HCC aggressive phenotype and treatment resistance. Claudin-6 mAbs or chimeric antigen receptor-T cells therapies are currently being clinically investigated for Claudin-6 overexpressing tumors. In conclusion, targeting Claudin proteins offers a novel clinical opportunity for the treatment of patients with advanced liver fibrosis and HCC.

Immunofluorescent Staining of Human Hepatic Multicellular Spheroids: A Model for Studying Liver Diseases

In vitro studies on liver diseases, such as non-alcoholic fatty liver disease, fibrosis, and hepatocellular carcinoma, are traditionally performed in two-dimensional (2D) cultures of isolated primary cells or immortalized cell lines. However, this approach has limitations, as 2D cultures inadequately replicate the cell-cell and cell-extracellular matrix interactions found in three-dimensional (3D) environments. To overcome this limitation, various 3D models, such as spheroids, have been developed. These spheroids serve as simplified biomimetic in vitro models for studying liver diseases. They can be generated using a variety of cells from healthy and pathological tissues, including liver cancer. Here, we present a comprehensive protocol for performing immunofluorescent staining and confocal imaging on whole human hepatic multicellular spheroids, utilizing primary cells or cell lines. The immunofluorescence technique is a potent tool to understand the spatial distribution of different cell types within the spheroids and define the interactions that occur among these cells.

A monoclonal antibody targeting nonjunctional claudin-1 inhibits fibrosis in patient-derived models by modulating cell plasticity

Tissue fibrosis is a key driver of end-stage organ failure and cancer, overall accounting for up to 45% of deaths in developed countries. There is a large unmet medical need for antifibrotic therapies. Claudin-1 (CLDN1) is a member of the tight junction protein family. Although the role of CLDN1 incorporated in tight junctions is well established, the function of nonjunctional CLDN1 (njCLDN1) is largely unknown. Using highly specific monoclonal antibodies targeting a conformation-dependent epitope of exposed njCLDN1, we show in patient-derived liver three-dimensional fibrosis and human liver chimeric mouse models that CLDN1 is a mediator and target for liver fibrosis. Targeting CLDN1 reverted inflammation-induced hepatocyte profibrogenic signaling and cell fate and suppressed the myofibroblast differentiation of hepatic stellate cells. Safety studies of a fully humanized antibody in nonhuman primates did not reveal any serious adverse events even at high steady-state concentrations. Our results provide preclinical proof of concept for CLDN1-specific monoclonal antibodies for the treatment of advanced liver fibrosis and cancer prevention. Antifibrotic effects in lung and kidney fibrosis models further indicate a role of CLDN1 as a therapeutic target for tissue fibrosis across organs. In conclusion, our data pave the way for further therapeutic exploration of CLDN1-targeting therapies for fibrotic diseases in patients.

Analysis and identification of potential type II helper T cell (Th2)-Related key genes and therapeutic agents for COVID-19

COVID-19 pandemic poses a severe threat to public health. However, so far, there are no effective drugs for COVID-19. Transcriptomic changes and key genes related to Th2 cells in COVID-19 have not been reported. These genes play an important role in host interactions with SARS-COV-2 and may be used as promising target. We analyzed five COVID-19-associated GEO datasets (GSE157103, GSE152641, GSE171110, GSE152418, and GSE179627) using the xCell algorithm and weighted gene co-expression network analysis (WGCNA). Results showed that 5 closely correlated modular genes to COVID-19 and Th2 cell enrichment levels, including purple, blue, pink, tan and turquoise, were intersected with differentially expressed genes (DEGs) and 648 shared genes were obtained. GO and KEGG pathway enrichment analyses revealed that they were enriched in cell proliferation, differentiation, and immune responses after virus infection. The most significantly enriched pathway involved the regulation of viral life cycle. Three key genes, namely CCNB1, BUB1, and UBE2C, may clarify the pathogenesis of COVID-19 associated with Th2 cells. 11 drug candidates were identified that could down-regulate three key genes using the cMAP database and demonstrated strong drugs binding energies aganist the three keygenes using molecular docking methods. BUB1, CCNB1 and UBE2C were identified key genes for COVID-19 and could be promising therapeutic targets.

Cholesterol-Mediated Seeding of Protein Corona on DNA Nanostructures for Targeted Delivery of Oligonucleotide Therapeutics to Treat Liver Fibrosis

The protein corona is a protein layer formed on the surface of nanoparticles administered in vivo and considerably affects the in vivo fate of nanoparticles. Although it is challenging to control protein adsorption on nanoparticles precisely, the protein corona may be harnessed to develop a targeted drug delivery system if the nanoparticles are decorated with a ligand with enhanced affinity to target tissue- and cell-homing proteins. Here, we prepared a DNA tetrahedron with trivalent cholesterol conjugation (Chol₃-Td) that can induce enhanced interaction with lipoproteins in serum, which in situ generates the lipoprotein-associated protein corona on a DNA nanostructure favorable for cells abundantly expressing lipoprotein receptors in the liver, such as hepatocytes in healthy mice and myofibroblasts in fibrotic mice. Chol₃-Td was further adopted for liver delivery of antisense oligonucleotide (ASO) targeting TGF-β1 mRNA to treat liver fibrosis in a mouse model. The potency of ASO@Chol₃-Td was comparable to that of ASO conjugated with the clinically approved liver-targeting ligand, trivalent N-acetylgalactosamine (GalNAc₃), demonstrating the potential of Chol₃-Td as a targeted delivery system for oligonucleotide therapeutics. This study suggests that controlled seeding of the protein corona on nanomaterials can provide a way to steer nanoparticles into the target area.

Molecular Crosstalk between the Hepatitis C Virus and the Extracellular Matrix in Liver Fibrogenesis and Early Carcinogenesis

Simple Summary

In the era of direct-acting antivirals against the hepatitis C virus (HCV), curing chronic hepatitis C has become a reality. However, while replicating chronically, HCV creates a peculiar state of inflammation and oxidative stress in the infected liver, which fuels DNA damage at the onset of HCV-induced hepatocellular carcinoma (HCC). This cancer, the second leading cause of death by cancer, remains of bad prognosis when diagnosed. This review aims to decipher how HCV durably alters elements of the extracellular matrix that compose the liver microenvironment, directly through its viral proteins or indirectly through the induction of cytokine secretion, thereby leading to liver fibrosis, cirrhosis, and, ultimately, HCC.

Abstract

Chronic infection by the hepatitis C virus (HCV) is a major cause of liver diseases, predisposing to fibrosis and hepatocellular carcinoma. Liver fibrosis is characterized by an overly abundant accumulation of components of the hepatic extracellular matrix, such as collagen and elastin, with consequences on the properties of this microenvironment and cancer initiation and growth. This review will provide an update on mechanistic concepts of HCV-related liver fibrosis/cirrhosis and early stages of carcinogenesis, with a dissection of the molecular details of the crosstalk during disease progression between hepatocytes, the extracellular matrix, and hepatic stellate cells.

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.

Impact of hepatitis C virus and alcohol, alone and combined, on the unfolded protein response in primary human hepatocytes

Hepatitis C virus (HCV) infection and alcohol abuse are leading causes of chronic liver disease and frequently coexist in patients. The unfolded protein response (UPR), a cellular stress response ranging along a spectrum from cytoprotection to apoptosis commitment, has emerged as a major contributor to human diseases including liver injuries. However, the literature contains conflicting reports as to whether HCV and ethanol activate the UPR and which UPR genes are involved. Here we have used primary human hepatocytes (PHH) to reassess this issue and address combined impacts. In this physiologically relevant model, either stressor activated a chronic complete UPR. However, the levels of UPR gene induction were only modest in the case of HCV infection. Moreover, when combined to the strong stressor thapsigargin, ethanol exacerbated the activation of pro-apoptotic genes whereas HCV tended to limit the induction of key UPR genes. The UPR resulting from HCV plus ethanol was comparable to that induced by ethanol alone with the notable exception of three pro-survival genes the expressions of which were selectively enhanced by HCV. Interestingly, HCV genome replication was maintained at similar levels in PHH exposed to ethanol. In conclusion, while both HCV and alcohol activate the hepatocellular UPR, only HCV manipulates UPR signalling in the direction of a cytoprotective response, which appears as a viral strategy to spare its own replication.

Hepatitis C Virus Improves Human Tregs Suppressive Function and Promotes Their Recruitment to the Liver

Background: The role of regulatory T cells (Tregs) is now well established in the progression of hepatocellular carcinoma (HCC) linked to Hepatitis C virus (HCV) infection. However, nothing is known about the potential interplay between Tregs and HCV. In this pilot study, we have investigated the ability of Tregs to hang HCV on and the subsequent effect on their suppressive function and phenotype. Moreover, we have evaluated how HCV could promote the recruitment of Tregs by infected primary human hepatocytes. Methods: Tregs of healthy donors were incubated with JFH-1/HCVcc. Viral inoculation was assessed using adapted assays (RT-qPCR, Flow Citometry (FACS) and Western Blot (WB). Expression of Tregs phenotypic (CD4, CD25, CD127 and Foxp3) and functional (IL-10, GZMB, TGF-β1 and IL-2) markers was monitored by RT-qPCR, FACS and ELISA. Suppressive activity was validated by suppressive assays. Tregs recruitment by infected primary hepatic cells was evaluated using Boyden Chamber. Results: Tregs express the classical HCV receptors (CD81, CLDN1 and LDLR) and some co-receptors (CD5). HCV inoculation significantly increases the suppressive phenotype and activity of Tregs, and raises their anergy by inducing an unexpected IL-2 production. Moreover, HCV infection induces the expression of chemokines (CCL17, CXCL16, and CCL20) by primary hepatic human hepatocytes and chemokine receptors (CCR4, CXCR6 and CCR6) by Tregs. Finally, infected hepatocytes have a significantly higher potential to recruit Tregs in a seemingly CCL20-dependent manner. Conclusions: Direct interaction between HCV and Tregs represents a newly defined mechanism that could potentiate HCV immune evasion and favor intratumoral recruitment contributing to HCC progression.

Wnt/β-Catenin Signaling as a Potential Target for the Treatment of Liver Cirrhosis Using Antifibrotic Drugs

Cirrhosis is a form of liver fibrosis resulting from chronic hepatitis and caused by various liver diseases, including viral hepatitis, alcoholic liver damage, nonalcoholic steatohepatitis, and autoimmune liver disease. Cirrhosis leads to various complications, resulting in poor prognoses; therefore, it is important to develop novel antifibrotic therapies to counter liver cirrhosis. Wnt/β-catenin signaling is associated with the development of tissue fibrosis, making it a major therapeutic target for treating liver fibrosis. In this review, we present recent insights into the correlation between Wnt/β-catenin signaling and liver fibrosis and discuss the antifibrotic effects of the cAMP-response element binding protein/β-catenin inhibitor PRI-724.

HCV derived from sera of HCV-infected patients induces pro-fibrotic effects in human primary fibroblasts by activating GLI2

Hepatitis C virus (HCV) infection is a leading cause of liver fibrosis, especially in developing countries. The process is characterized by the excess accumulation of ECM that may lead, over time, to hepatic cirrhosis, liver failure and also to hepatocarcinoma. The direct role of HCV in promoting fibroblasts trans-differentiation into myofibroblasts, the major fibrogenic cells, has not been fully clarified. In this study, we found that HCV derived from HCV-infected patients infected and directly induced the trans-differentiation of human primary fibroblasts into myofibroblasts, promoting fibrogenesis. This effect correlated with the activation of GLI2, one of the targets of Hedgehog signaling pathway previously reported to be involved in myofibroblast generation. Moreover, GLI2 activation by HCV correlated with a reduction of autophagy in fibroblasts, that may further promoted fibrosis. GLI2 inhibition by Gant 61 counteracted the pro-fibrotic effects and autophagy inhibition mediated by HCV, suggesting that targeting HH/GLI2 pathway might represent a promising strategy to reduce the HCV-induced fibrosis.

Development of an in vitro model to test antifibrotic drugs on primary human liver myofibroblasts

We have developed a culture model to assess antifibrotic drugs using normal human liver myofibroblasts (HLMFs) obtained from 31 subjects. Activation was evaluated in terms of α-smooth muscle actin (α-SMA) and collagen 1 (Coll1) expression using RT-PCR, and proliferation as the uptake of 5-ethynil-2'-deoxyuridine. Under analysis of variance, between-subject differences accounted for 70% of all variability and inter-experiment differences for 30%. The sensitivity of the model was determined by quantifying the effects in terms of relative expression, which were 0.74±0.03 for cyclosporine A (CsA) and 2.4±0.10 for transforming growth factor-beta (TGF-β) (P<0.0001 vs no treatment) for α-SMA expression. Inter-subject variations in α-SMA and Coll1 expression enabled the classification of subjects as potentially low or high fibrosers. Finally, we observed that pirfenidone (which has beneficial effects in vivo) significantly reduced the expressions of α-SMA and Coll1, whereas the angiotensin-converting enzyme inhibitor losartan (which has no effect in vivo) had no significant effect. Our model may thus detect the antifibrotic properties of drugs. Antifibrotic drugs with promising clinical relevance could possibly be selected using a bank of HLMFs from high fibrosers.