Hepatic stellate cells express functional CXCR4: role in stromal cell-derived factor-1alpha-mediated stellate cell activation

HIV and gp120-induced lipid droplets loss in hepatic stellate cells contribute to profibrotic profile

Liver fibrosis is the excessive accumulation of extracellular matrix proteins, primarily collagen, in response to liver injury caused by chronic liver diseases. HIV infection accelerates the progression of liver fibrosis in patients co-infected with HCV or HBV compared to those who are only mono-infected. The early event in the progression of liver fibrosis involves the activation of hepatic stellate cells (HSCs), which entails the loss of lipid droplets (LD) to fuel the production of extracellular matrix components crucial for liver tissue healing. Thus, we are examining the mechanism by which HIV stimulates the progression of liver fibrosis. HIV-R5 tropic infection was unable to induce the expression of TGF-β, collagen deposition, α-smooth muscle actin (α-SMA), and cellular proliferation. However, this infection induced the secretion of the profibrogenic cytokine IL-6 and the loss of LD. This process involved the participation of peroxisome proliferator-activated receptor (PPAR)-α and an increase in lysosomal acid lipase (LAL), along with the involvement of Microtubule-associated protein 1 A/1B-light chain 3 (LC3), strongly suggesting that LD loss could occur through acid lipolysis. These phenomena were mimicked by the gp120 protein from the R5 tropic strain of HIV. Preincubation of HSCs with the CCR5 receptor antagonist, TAK-779, blocked gp120 activity. Additionally, experiments performed with pseudotyped-HIV revealed that HIV replication could also contribute to LD loss. These results demonstrate that the cross-talk between HSCs and HIV involves a series of interactions that help explain some of the mechanisms involved in the exacerbation of liver damage observed in co-infected individuals.

Demethylation in promoter region of severely damaged hepatocytes enhances chemokine receptor CXCR4 gene expression

The liver is known to possess remarkable regenerative potential, but persistent inflammation or severe acute injury can lead to liver fibrosis and incomplete regeneration, ultimately resulting in liver failure. Recent studies have shown that the axis of two types of CXCL12 receptors, CXCR4 and CXCR7, plays a crucial role in liver fibrosis and regeneration. The present study aimed to investigate the regulatory factors involved in CXCR4 expression in injured liver. Immunohistochemical screening of liver tissue samples collected during liver transplantation revealed a reciprocal expression pattern between CXCR4 and MeCP2. An in vitro system involving cultured cell lines and H2O2 treatment was established to study the impact of oxidative stress on signaling pathways and epigenetic alterations that affect CXCR4 mRNA expression. Operating through distinct signaling pathways, H2O2 treatment induced a dose-dependent increase in CXCR4 expression in both hepatocyte- and intrahepatic cholangiocyte-derived cells. Treatment of the cells with trichostatin and azacytidine modulated CXCR4 expression in hepatocytes by modifying the methylation status of CpG dinucleotides located in a pair of TA repeats adjacent to the TATA box of the CXCR4 gene promoter. Only MeCP2 bound to oligonucleotides representing the TATA box region when the cytosine residues within the sequence were methylated, as revealed by electrophoretic mobility shift assay (EMSA). Methylation-specific PCR analysis of microdissected samples revealed a correlation between the loss of CpG methylation and the upregulation of CXCR4 in injured hepatocytes, replicating the findings from the in vitro study. Besides the conventional MEK/ERK and NF-κB signaling pathways that activate CXCR4 in intrahepatic cholangiocytes, the unique epigenetic modifications observed in hepatocytes might also contribute to a shift in the CXCR4-CXCR7 balance towards CXCR4, leading to irreversible liver injury and fibrosis. This study highlights the importance of epigenetic modifications in regulating CXCR4 expression in liver injury and fibrosis.

Chronic liver diseases: From development to novel pharmacological therapies: IUPHAR Review 37

Chronic liver diseases comprise a broad spectrum of burdensome diseases that still lack effective pharmacological therapies. Our research group focuses on fibrosis, which is a major precursor of liver cirrhosis. Fibrosis consists in a progressive disturbance of liver sinusoidal architecture characterised by connective tissue deposition as a reparative response to tissue injury. Multifactorial events and several types of cells participate in fibrosis initiation and progression, and the process still needs to be completely understood. The development of experimental models of liver fibrosis alongside the identification of critical factors progressing fibrosis to cirrhosis will facilitate the development of more effective therapeutic approaches for such condition. This review provides an overlook of the main process leading to hepatic fibrosis and therapeutic approaches that have emerged from a deep knowledge of the molecular regulation of fibrogenesis in the liver. LINKED ARTICLES: This article is part of a themed issue on Translational Advances in Fibrosis as a Therapeutic Target. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.22/issuetoc.

Correlation between SDF-1α, CD34 positive hematopoietic stem cells and CXCR4 expression with liver fibrosis in CCl4 rat model

BACKGROUND

One of the most frequent disorders is liver fibrosis. An improved understanding of the different events during the process of liver fibrosis & its reversibility could be helpful in its staging and in finding potential therapeutic agents.

AIM

The goal of this research was to evaluate the relationship among CD34 + HPSCs, SDF-1α, and CXCR4 receptor expression with the percentage of the area of hepatic fibrosis.

MATERIALS AND METHODS

Thirty-six male Sprague-Dawley rats were separated into the control group, liver injury group & spontaneous reversion group. The liver injury was induced by using 2 ml/kg CCl4 twice a week. Flow cytometric examination of CD34 + cells in the blood & liver was performed. Bone marrow & liver samples were taken for evaluation of the SDF-1α mRNA by PCR. Liver specimens were stained for histopathological and CXCR4 immuno-expression evaluation.

RESULTS

In the liver injury group, the hepatic enzymes, fibrosis area percentage, CXCR4 receptor expression in the liver, CD34 + cells in the blood and bone marrow & the level SDF-1α in the liver and its concentration gradient were statistically significantly elevated with the progression of the liver fibrosis. On the contrary, SDF-1α in the bone marrow was statistically significantly reduced with the development of liver fibrosis. During the spontaneous reversion group, all the studied parameters apart from SDF-1α in the bone marrow were statistically substantially decreased compared with the liver injury group. We found a statistically substantial positive correlation between fibrosis area and all of the following: liver enzymes, CXCR4 receptor expression in the liver, CD34 + cells in the blood and liver, and SDF- 1α in the liver and its concentration gradient. In conclusion, in CCl4 rat model, the fibrosis area is significantly correlated with many parameters in the blood, bone marrow, and liver, which can be used during the process of follow-up during the therapeutic interventions.

Distinct Inflammatory Milieu in Patients With Right Heart Failure

BACKGROUND

Right heart failure (RHF) is associated with worse clinical outcomes. In addition to hemodynamic perturbations, the syndrome of RHF involves liver congestion and dysfunction. The mechanisms that underlie heart-liver interactions are poorly understood and may involve secreted factors. As a first step to understand the cardiohepatic axis, we sought to elucidate the circulating inflammatory milieu in patients with RHF.

METHODS

Blood samples were collected from the inferior vena cava and hepatic veins during right heart catheterization from 3 groups of patients: (1) controls with normal cardiac function, (2) patients with heart failure who did not meet all criteria of RHF, and (3) patients who met prespecified criteria for RHF defined by hemodynamic and echocardiographic parameters. We performed a multiplex protein assay to survey levels of several circulating markers and analyzed their association with mortality and the need for a left ventricular assist device or heart transplant. Finally, we leveraged publicly available single-cell RNA sequencing data and performed tissue imaging to evaluate the expression of these factors in the liver.

RESULTS

In this study, RHF was associated with elevated levels of a subset of cytokines/chemokines/growth factors compared with controls. In particular, soluble CD163 (cluster of differentiation 163) and CXCL12 (chemokine [C-X-C motif] ligand 12) were higher in RHF and predicted left ventricular assist device/transplant-free survival in an independent validation cohort. Furthermore, single-cell RNA sequencing and immunohistochemistry of human liver biopsies suggest that these factors are expressed by Kupffer cells and may be liver derived.

CONCLUSIONS

RHF is associated with a distinct circulating inflammatory profile. Soluble CD163 and CXCL12 are novel biomarkers that can prognosticate patient outcomes. Future studies to define how these molecules influence heart failure phenotypes and disease progression may lead to new approaches to the management of patients with RHF.

A Distinct Inflammatory Milieu in Patients with Right Heart Failure

Background

Right heart failure (RHF) is associated with worse clinical outcomes. In addition to hemodynamic perturbations, the syndrome of RHF involves liver congestion and dysfunction. The mechanisms that underlie heart-liver interactions are poorly understood and may involve secreted factors. As a first step to understand the cardiohepatic axis, we sought to elucidate the circulating inflammatory milieu in patients with RHF.

Methods

Blood samples were collected from the IVC and hepatic veins during right heart catheterization from 3 groups of patients: 1) controls with normal cardiac function, 2) patients with heart failure (HF) who did not meet all criteria of RHF, and 3) patients who met prespecified criteria for RHF defined by hemodynamic and echocardiographic parameters. We performed multiplex protein assay to survey levels of several circulating markers and analyzed their association with mortality and need for left ventricular assist device or heart transplant. Finally, we leveraged publicly available single cell RNA sequencing (scRNAseq) data and performed tissue imaging to evaluate expression of these factors in the liver.

Results

In this study of 43 patients, RHF was associated with elevated levels of a subset of cytokines/chemokines/growth factors compared to controls. In particular, soluble CD163 (sCD163) and CXCL12 were higher in RHF and predicted survival in an independent validation cohort. Furthermore, scRNAseq and immunohistochemistry of human liver biopsies suggest that these factors are expressed by Kupffer cells and may be liver derived.

Conclusions

RHF is associated with a distinct circulating inflammatory profile. sCD163 and CXCL12 are novel biomarkers that can prognosticate patient outcomes. Future studies to define how these molecules influence HF phenotypes and disease progression may lead to new approaches to management of patients with RHF.

S100a16 deficiency prevents hepatic stellate cells activation and liver fibrosis via inhibiting CXCR4 expression

INTRODUCTION

Liver fibrosis caused by hepatic stellate cells (HSCs) activation is implicated in the pathogenesis of liver diseases. To date, there has been no effective intervention means for this process. S100 proteins are calcium-binding proteins that regulate cell growth and differentiation. This study aimed to investigate whether S100A16 induces HSCs activation and participates in liver fibrosis progression.

METHODS

HSCs were isolated, and the relationship between S100A16 expression and HSCs activation was studied. S100a16 knockdown and transgenic mice were generated and subjected to HSCs activation and liver fibrosis stimulated by different models. Clinical samples were collected for further confirmation. Alterations in gene expression in HSCs were investigated, using transcriptome sequencing to determine the underlying mechanisms.

RESULTS

We observed increased S100A16 levels during HSCs activation. Genetic silencing of S100a16 prevented HSCs activation in vitro. Furthermore, S100a16 silencing exhibited obvious protective effects against HSCs activation and fibrosis progression in mice. In contrast, S100a16 transgenic mice exhibited spontaneous liver fibrosis. S100A16 was also upregulated in the HSCs of patients with fibrotic liver diseases. RNA sequencing revealed that C-X-C motif chemokine receptor 4 (Cxcr4) gene was a crucial regulator of S100A16 induction during HSCs activation. Mechanistically, S100A16 bound to P53 to induce its degradation; this augmented CXCR4 expression to activate ERK 1/2 and AKT signaling, which then promoted HSCs activation and liver fibrosis.

CONCLUSIONS

These data indicate that S100a16 deficiency prevents liver fibrosis by inhibiting Cxcr4 expression. Targeting S100A16 may provide insight into the pathogenesis of liver fibrosis and pave way for the design of novel clinical therapeutic strategies.

Ym1+ macrophages orchestrate fibrosis, lesion growth, and progression during development of murine pancreatic cancer

Desmoplasia around pancreatic lesions is a barrier for immune cells and a hallmark of developing and established pancreatic cancer. However, the contribution of the innate immune system to this process is ill-defined. Using the KC mouse model and primary cells in vitro, we show that alternatively activated macrophages (AAM) crosstalk with pancreatic lesion cells and pancreatic stellate cells (PSCs) to mediate fibrosis and progression of lesions. TGFβ1 secreted by AAM not only drives activation of quiescent PSCs but also in activated PSCs upregulates expression of TIMP1, a factor previously shown as crucial in fibrosis. Once activated, PSCs auto-stimulate proliferation via CXCL12. Furthermore, we found that TIMP1/CD63 signaling mediates PanIN lesion growth and TGFβ1 contributes to a cadherin switch and drives structural collapse of lesions, indicating a potential progression step. Taken together, our data indicate TGFβ1 produced by Ym1+ AAM as a major driver of processes that initiate the development of pancreatic cancer.

Dually Active Polycation/miRNA Nanoparticles for the Treatment of Fibrosis in Alcohol-Associated Liver Disease

Alcohol-associated liver disease (AALD) is a major cause of liver disorders worldwide. Current treatment options are limited, especially for AALD-associated fibrosis. Promising approaches include RNA interference for miR-155 overexpression in Kupffer cells (KCs), as well as the use of CXCR4 antagonists that inhibit the activation of hepatic stellate cells (HSCs) through the CXCL12/CXCR4 axis. The development of dual-functioning nanoparticles for the effective delivery of antifibrotic RNA together with a CXCR4 inhibitor thus promises to improve the treatment of AALD fibrosis. In this study, cholesterol-modified polymeric CXCR4 inhibitor (Chol-PCX) was synthesized and used to encapsulate anti-miR-155 or non-coding (NC) miRNA in the form of Chol-PCX/miRNA nanoparticles. The results indicate that the nanoparticles induce a significant miR-155 silencing effect both in vitro and in vivo. Treatment with the Chol-PCX/anti-miR-155 particles in a model of moderate alcohol consumption with secondary liver insult resulted in a significant reduction in aminotransferase enzymes as well as collagen content in the liver parenchyma. Overall, our data support the use of Chol-PCX as a carrier for anti-miR-155 for the combined therapeutic inhibition of CXCR4 and miR-155 expression as a way to improve fibrotic damage in the liver.

Role of Circulating Hematopoietic Fibrocytes in Chronic Hepatitis C Patients Induced Liver Fibrosis

Background: Bone marrow derived fibrocytes may play an important role in pathogenesis and resolution of liver fibrosis. These cells may offer new approaches for better understanding the pathogenesis of liver fibrosis. Aim of the work: To define the proportion of circulating fibrocytes with hematopoietic progenitor origin as defined by CD45 and CD34 positivity and to assess whether they are increased in patients with chronic C hepatitis in correlation to the degree of liver fibrosis. Subjects and Methods: Sixty HCV patients were classified according to METAVIR score into 4 stages of liver fibrosis, 15 age and sex-matched controls were included. Flowcytometric analysis for circulating levels of fibrocytes CD34+ve cells, CD45+ve cells, collagen type I+ve cells and CXCR4+ve cells was carried out using monoclonal antibodies (anti-CD34, CD45, collagen type I and CD184). GM-CSF, TGF-β and α-SMA were assessed using ELISA. Results and Conclusions: A significant increase in the circulating levels of GM-CSF, TGF- β and α-SMA, with a significant increase in the percentage of cells express CXCR4and in the co expression of CD34, CD45 and collagen type I positive cells in different groups of patients compared to control group, denoting the presence of an increased proportion of circulating fibrocytes in peripheral blood of these patients. The percentage of fibrocytes that positively expression CD34, CD45, collagen type I and CXCR4, were increased in step wise fashion in conjunction with worsening severity of liver disease. Liver fibrosis is associated with increased levels of circulating TGF-β1 and lipopolysaccharide, activation of myofibroblasts, and extensive deposition of extracellular matrix, mostly collagen Type I. TGF-β and LPS play a critical role in fibrogenesis and trigger fibrocyte recruitment to the injured liver promoting their differentiation into collagen type I producing myofibroblast, supporting that fibrocytes may become a novel target for anti fibrotic therapy.

Hepatic Stellate Cell-Immune Interactions in NASH

Nonalcoholic fatty liver disease (NAFLD) is the dominant cause of liver disease worldwide. Nonalcoholic steatohepatitis (NASH), a more aggressive presentation of NAFLD, is characterized by severe hepatocellular injury, inflammation, and fibrosis. Chronic inflammation and heightened immune cell activity have emerged as hallmark features of NASH and key drivers of fibrosis through the activation of hepatic stellate cells (HSCs). Recent advances in our understanding of the molecular and cellular pathways in NASH have highlighted extensive crosstalk between HSCs and hepatic immune populations that strongly influences disease activity. Here, we review these findings, emphasizing the roles of HSCs in liver immunity and inflammation, key cell-cell interactions, and exciting areas for future investigation.

A Step Closer to the "Fourth 90": A Practical Narrative Review of Diagnosis and Management of Nutritional Issues of People Living with HIV

The quality of life of people living with HIV (PLWH) has remarkably increased thanks to the introduction of combined antiretroviral therapy. Still, PLWH are exposed to an increased risk of cardiovascular diseases, diabetes, chronic kidney disease, and liver disease. Hence, the purpose of this review is to summarize the current knowledge about diagnosis and nutritional management with specific indication of macro and micronutrients intake for the main comorbidities of PLWH. In fact, a prompt diagnosis and management of lifestyle behaviors are fundamental steps to reach the “fourth 90”. To achieve an early diagnosis of these comorbidities, clinicians have at their disposal algorithms such as the Framingham Score to assess cardiovascular risk; transient elastography and liver biopsy to detect NAFLD and NASH; and markers such as the oral glucose tolerance test and GFR to identify glucose impairment and renal failure, respectively. Furthermore, maintenance of ideal body weight is the goal for reducing cardiovascular risk and to improve diabetes, steatosis and fibrosis; while Mediterranean and low-carbohydrate diets are the dietetic approaches proposed for cardioprotective effects and for glycemic control, respectively. Conversely, diet management of chronic kidney disease requires different nutritional assessment, especially regarding protein intake, according to disease stage and eventually concomitant diabetes.

Emerging Importance of Chemokine Receptor CXCR4 and Its Ligand in Liver Disease

Chemokine receptors are members of the G protein-coupled receptor superfamily, which together with chemokine ligands form chemokine networks to regulate various cellular functions, immune and physiological processes. These receptors are closely related to cell movement and thus play a vital role in several physiological and pathological processes that require regulation of cell migration. CXCR4, one of the most intensively studied chemokine receptors, is involved in many functions in addition to immune cells recruitment and plays a pivotal role in the pathogenesis of liver disease. Aberrant CXCR4 expression pattern is related to the migration and movement of liver specific cells in liver disease through its cross-talk with a variety of significant cell signaling pathways. An in-depth understanding of CXCR4-mediated signaling pathway and its role in liver disease is critical to identifying potential therapeutic strategies. Current therapeutic strategies for liver disease mainly focus on regulating the key functions of specific cells in the liver, in which the CXCR4 pathway plays a crucial role. Multiple challenges remain to be overcome in order to more effectively target CXCR4 pathway and identify novel combination therapies with existing strategies. This review emphasizes the role of CXCR4 and its important cell signaling pathways in the pathogenesis of liver disease and summarizes the targeted therapeutic studies conducted to date.

Nanotechnology of Tyrosine Kinase Inhibitors in Cancer Therapy: A Perspective

Nanotechnology is an important application in modern cancer therapy. In comparison with conventional drug formulations, nanoparticles ensure better penetration into the tumor mass by exploiting the enhanced permeability and retention effect, longer blood circulation times by a reduced renal excretion and a decrease in side effects and drug accumulation in healthy tissues. The most significant classes of nanoparticles (i.e., liposomes, inorganic and organic nanoparticles) are here discussed with a particular focus on their use as delivery systems for small molecule tyrosine kinase inhibitors (TKIs). A number of these new compounds (e.g., Imatinib, Dasatinib, Ponatinib) have been approved as first-line therapy in different cancer types but their clinical use is limited by poor solubility and oral bioavailability. Consequently, new nanoparticle systems are necessary to ameliorate formulations and reduce toxicity. In this review, some of the most important TKIs are reported, focusing on ongoing clinical studies, and the recent drug delivery systems for these molecules are investigated.

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.

Macrophages contribute to liver repair after monocrotaline-induced liver injury via SDF-1/CXCR4

Monocrotaline (MCT) administration induces liver injury in rodents that mimics the pathology of human sinusoidal obstruction syndrome. MCT-induced SOS models are used to investigate the mechanism of injury and optimize treatment strategies. However, the processes underlying liver repair are largely unknown. Specifically, the role of macrophages, the key drivers of liver repair, has not been elucidated. The current study aimed to examine the role of macrophages in the repair of MCT-induced liver injury in male C57/BL6 mice. Maximal liver injury occurred at 48 h post-MCT treatment, followed by repair at 120 h post-treatment. Immunofluorescence analysis revealed that CD68⁺ macrophages were recruited to the injured regions after MCT treatment. This was associated with the decreased expression of genes related to a pro-inflammatory macrophage phenotype and the increased expression of those associated with a reparative macrophage phenotype during the repair phase. The results also revealed that stromal cell-derived factor-1 (SDF-1) and its receptor C-X-C chemokine receptor-4 (CXCR4) were upregulated, and CD68⁺ macrophages were co-localized with CXCR4 expression. Treatment of mice with AMD3100, a CXCR4 antagonist, delayed liver repair and increased the expression of genes related to a pro-inflammatory macrophage phenotype. In contrast, SDF-1 treatment stimulated liver repair and increased the expression of genes related to a reparative macrophage phenotype. The results suggested that macrophages accumulate in the liver and repair damaged tissue after MCT treatment, and that the SDF-1-CXCR4 axis is involved in this process.

Liver sinusoidal endothelial cells are implicated in multiple fibrotic mechanisms

Chronic liver diseases are attributed to liver injury. Development of fibrosis from chronic liver diseases is a dynamic process that involves multiple molecular and cellular processes. As the first to be impacted by injury, liver sinusoidal endothelial cells (LSECs) are involved in the pathogenesis of liver diseases caused by a variety of etiologies. Moreover, capillarization of LSECs has been recognized as an important event in the development of chronic liver diseases and fibrosis. Studies have reported that various cytokines (such as vascular endothelial growth factor, transforming growth factor-β), and pathways (such as hedgehog, and Notch), as well as epigenetic and metabolic factors are involved in the development of LSEC-mediated liver fibrosis. This review describes the complexity and plasticity of LSECs in fibrotic liver diseases from several perspectives, including the cross-talk between LSECs and other intra-hepatic cells. Moreover, it summarizes the mechanisms of several kinds of LSECs-targeting anti-fibrosis chemicals, and provides a theoretical basis for future studies.

Ursodesoxycholic acid alleviates liver fibrosis via proregeneration by activation of the ID1-WNT2/HGF signaling pathway

BACKGROUND

The human liver possesses a remarkable capacity for self-repair. However, liver fibrosis remains a serious medical concern, potentially progressing to end-stage liver cirrhosis and even death. Liver fibrosis is characterized by excess accumulation of extracellular matrix in response to chronic injury. Liver regenerative ability, a strong indicator of liver health, is important in resisting fibrosis. In this study, we provide evidence that ursodesoxycholic acid (UDCA) can alleviate liver fibrosis by promoting liver regeneration via activation of the ID1-WNT2/hepatocyte growth factor (HGF) pathway.

METHODS

Bile duct ligation (BDL) and partial hepatectomy (PH) mouse models were used to verify the effects of UDCA on liver fibrosis, regeneration, and the ID1-WNT2/HGF pathway. An Id1 knockdown mouse model was also used to assess the role of Id1 in UDCA alleviation of liver fibrosis.

RESULTS

Our results demonstrate that UDCA can alleviate liver fibrosis in the BDL mice and promote liver regeneration via the ID1-WNT2/HGF pathway in PH mice. In addition, Id1 knockdown abolished the protection afforded by UDCA in BDL mice.

CONCLUSIONS

We conclude that UDCA protects against liver fibrosis by proregeneration via activation of the ID1-WNT2/HGF pathway.

Role of G Protein-Coupled Receptors in Hepatic Stellate Cells and Approaches to Anti-Fibrotic Treatment of Non-Alcoholic Fatty Liver Disease

The prevalence of non-alcoholic fatty liver disease (NAFLD) is globally increasing. Gaining control over disease-related events in non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, is currently an unmet medical need. Hepatic fibrosis is a critical prognostic factor in NAFLD/NASH. Therefore, a better understanding of the pathophysiology of hepatic fibrosis and the development of related therapies are of great importance. G protein-coupled receptors (GPCRs) are cell surface receptors that mediate the function of a great variety of extracellular ligands. GPCRs represent major drug targets, as indicated by the fact that about 40% of all drugs currently used in clinical practice mediate their therapeutic effects by acting on GPCRs. Like many other organs, various GPCRs play a role in regulating liver function. It is predicted that more than 50 GPCRs are expressed in the liver. However, our knowledge of how GPCRs regulate liver metabolism and fibrosis in the different cell types of the liver is very limited. In particular, a better understanding of the role of GPCRs in hepatic stellate cells (HSCs), the primary cells that regulate liver fibrosis, may lead to the development of drugs that can improve hepatic fibrosis in NAFLD/NASH. In this review, we describe the functions of multiple GPCRs expressed in HSCs, their roles in liver fibrogenesis, and finally speculate on the development of novel treatments for NAFLD/NASH.

Cyclam-Modified Polyethyleneimine for Simultaneous TGFβ siRNA Delivery and CXCR4 Inhibition for the Treatment of CCl4-Induced Liver Fibrosis

BACKGROUND

Liver fibrosis is a chronic liver disease with excessive production of extracellular matrix proteins, leading to cirrhosis, hepatocellular carcinoma, and death.

PURPOSE

This study aimed at the development of a novel derivative of polyethyleneimine (PEI) that can effectively deliver transforming growth factor β (TGFβ) siRNA and inhibit chemokine receptor 4 (CXCR4) for TGFβ silencing and CXCR4 Inhibition, respectively, to treat CCl₄-induced liver fibrosis in a mouse model.

METHODS

Cyclam-modified PEI (PEI-Cyclam) was synthesized by incorporating cyclam moiety into PEI by nucleophilic substitution reaction. Gel electrophoresis confirmed the PEI-Cyclam polyplex formation and stability against RNAase and serum degradation. Transmission electron microscopy and zeta sizer were employed for the morphology, particle size, and zeta potential, respectively. The gene silencing and CXCR4 targeting abilities of PEI-Cyclam polyplex were evaluated by luciferase and CXCR4 redistribution assays, respectively. The histological and immunohistochemical staining determined the anti-fibrotic activity of PEI-Cyclam polyplex. The TGFβ silencing of PEI-Cyclam polyplex was authenticated by Western blotting.

RESULTS

The ¹H NMR of PEI-Cyclam exhibited successful incorporation of cyclam content onto PEI. The PEI-Cyclam polyplex displayed spherical morphology, positive surface charge, and stability against RNAse and serum degradation. Cyclam modification decreased the cytotoxicity and demonstrated CXCR4 antagonistic and luciferase gene silencing efficiency. PEI-Cyclam/siTGFβ polyplexes decreased inflammation, collagen deposition, apoptosis, and cell proliferation, thus ameliorating liver fibrosis. Also, PEI-Cyclam/siTGFβ polyplex significantly downregulated α-smooth muscle actin, TGFβ, and collagen type III.

CONCLUSION

Our findings validate the feasibility of using PEI-Cyclam as a siRNA delivery vector for simultaneous TGFβ siRNA delivery and CXCR4 inhibition for the combined anti-fibrotic effects in a setting of CCl₄-induced liver fibrosis.

Chemokine CXCL14 acts as a potential genetic target for liver fibrosis

There are multiple causes of liver fibrosis, common ones include ethanol, toxins, and cholestasis. However, whether these different etiologies lead to the same pathological outcomes contain common genetic targets or signaling pathways, the current research has not attracted widespread attention. GSE40041 and GSE55747 were downloaded from the Gene Expression Omnibus (GEO) database. GSE40041 and GSE55747 represent the differential expression profiles in the liver of mice with bile duct ligation (BDL) and carbon tetrachloride (CCl4) induced liver fibrosis models, respectively. By using GEO2R, 701 differential expression genes (DEGs) in GSE40041 and 6540 DEGs in GSE55747 were identified. 260 co-DEGs were shared and extracted for gene ontology (GO) analysis. Through GO analysis, it was found that the regulation of cell migration in biological processes (BPs) was closely related to the pathogenesis of liver fibrosis, and the genes involved in this process include a key gene, chemokine (C-X-C motif) ligand 14 (CXCL14). Subsequently, further bioinformatic analysis showed that CXCL14 may be regulated by miR-122 to participate in the progression of liver fibrosis. Then real-time PCR and western blotting were performed to validate the expression of CXCL14 in liver tissue after liver fibrosis caused by different etiologies (ethanol, CCl4). The expression of CXCL4 in liver fibrosis induced by BDL was verified in another GEO dataset. Basically consistent with our bioinformatics results, our experimental results showed that the expression of CXCL14 was most significantly increased in alcoholic liver fibrosis model, followed by CCl4-induced liver fibrosis, which was also significantly increased in the BDL-induced model. Thus, CXCL14 can act as a common potential genetic target for different liver fibrosis diseases.

The Chemokine Receptor CXCR4 in Cell Proliferation and Tissue Regeneration

The CXCR4 receptor upon binding its ligands triggers multiple signaling pathways that orchestrate cell migration, hematopoiesis and cell homing, and retention in the bone marrow. However, CXCR4 also directly controls cell proliferation of non-hematopoietic cells. This review focuses on recent reports pointing to its pivotal role in tissue regeneration and stem cell activation, and discusses the connection to the known role of CXCR4 in promoting tumor growth. The mechanisms may be similar in all cases, since regeneration often recapitulates developmental processes, and cancer often exploits developmental pathways. Moreover, cell migration and cell proliferation appear to be downstream of the same signaling pathways. A deeper understanding of the complex signaling originating from CXCR4 is needed to exploit the opportunities to repair damaged organs safely and effectively.

Space of Disse: a stem cell niche in the liver

Recent evidence indicates that the plasticity of preexisting hepatocytes and bile duct cells is responsible for the appearance of intermediate progenitor cells capable of restoring liver mass after injury without the need of a stem cell compartment. However, mesenchymal stem cells (MSCs) exist in all organs and are associated with blood vessels which represent their perivascular stem cell niche. MSCs are multipotent and can differentiate into several cell types and are known to support regenerative processes by the release of immunomodulatory and trophic factors. In the liver, the space of Disse constitutes a stem cell niche that harbors stellate cells as liver resident MSCs. This perivascular niche is created by extracellular matrix proteins, sinusoidal endothelial cells, liver parenchymal cells and sympathetic nerve endings and establishes a microenvironment that is suitable to maintain stellate cells and to control their fate. The stem cell niche integrity is important for the behavior of stellate cells in the normal, regenerative, aged and diseased liver. The niche character of the space of Disse may further explain why the liver can become an organ of extra-medullar hematopoiesis and why this organ is frequently prone to tumor metastasis.

Hypoxia upregulates Cxcl12 in hepatocytes by a complex mechanism involving hypoxia-inducible factors and transforming growth factor-β

INTRODUCTION

Cxcl12, or stromal-derived factor-1, is a chemokine produced by several hepatic cell types, including hepatocytes, after liver injury and surgical resection. Studies have revealed that Cxcl12 is important for regeneration of the liver after surgical resection and for development of liver fibrosis during chronic liver injury. While the function of Cxcl12 in the liver is well established, the mechanism by which Cxcl12 is upregulated is not fully understood. Because regions of hypoxia develop in the liver following injury, we tested the hypothesis that hypoxia upregulates Cxcl12 in hepatocytes by a hypoxia-inducible factor (HIF)-dependent mechanism.

METHODS

To test this hypothesis, primary mouse hepatocytes were isolated from the livers of HIF-1α-deficient mice or HIF-1β-deficient mice and exposed to 1% oxygen. Cxcl12 expression was increased following exposure of primary mouse hepatocytes to 1% oxygen. Previously we have shown, that in addition to HIFs, transforming growth factor-β is required for upregulation of a subset of genes in hypoxic hepatocytes. To examine the role of TGF-β in regulation of Cxcl12 during hypoxia, hepatocytes were pretreated with the TGF-β receptor I inhibitor, SB431542.

RESULTS

Upregulation of Cxcl12 by hypoxia was partially prevented in hepatocytes from HIF-1α-deficient mice and completely prevented in hepatocytes from HIF-1β-deficient hepatocytes. This suggests that under hypoxic conditions, both HIF-1α and HIF-2α regulate Cxcl12 in hepatocytes. Pretreatment of hepatocytes with SB431542 completely prevented upregulation Cxcl12 by hypoxia. Further, treatment of hepatocytes with recombinant TGF-β1 upregulated Cxcl12 in hepatocytes cultured in room air.

CONCLUSION

Collectively, these studies demonstrate that hypoxia upregulates Cxcl12 in primary mouse hepatocytes by a mechanism that involves HIFs and TGF-β.

Sex Differences, Cocaine Use, and Liver Fibrosis Among African Americans in the Miami Adult Studies on HIV Cohort

Background: HIV infection disproportionally affects African Americans. Liver disease is a major cause of non-HIV morbidity and mortality in this population. Substance abuse accelerates HIV disease and may facilitate progression of liver disease. This study investigated the relationship between sex differences and cocaine use with liver injury, characterized as hepatic fibrosis. Materials and Methods: A cross-sectional study was conducted on 544 African Americans [369 people living with HIV (PLWH) and 175 HIV seronegative] from the Miami Adult Studies on HIV (MASH) cohort. Cocaine use was determined with a validated self-reported questionnaire and confirmed with urine screen. Fasting blood was used to estimate liver fibrosis using the noninvasive fibrosis-4 (FIB-4) index. Results: Men living with HIV had 1.79 times higher odds for liver fibrosis than women living with HIV (p = 0.038). African American women had higher CD4 count (p = 0.001) and lower HIV viral load (p = 0.011) compared to African American men. Fewer women (PLWH and HIV seronegative) smoked cigarettes (p = 0.002), and fewer had hazardous or harmful alcohol use (p < 0.001) than men. Women also had higher body mass index (kg/m²) (p < 0.001) compared to men. No significant association was noted among HIV seronegative participants for liver fibrosis by sex differences or cocaine use. Among African Americans living with HIV, cocaine users were 1.68 times more likely to have liver fibrosis than cocaine nonusers (p = 0.044). Conclusions: Sex differences and cocaine use appear to affect liver disease among African Americans living with HIV pointing to the importance of identifying at-risk individuals to improve outcomes of liver disease.

Clinical significance of endothelial progenitor cells in patients with liver cirrhosis with or without hepatocellular carcinoma

BACKGROUND AND OBJECTIVE

The role of endothelial progenitor cells in patients with cirrhosis has seldom been investigated. This study was conducted to assess the clinical significance of circulating endothelial progenitor cells in patients with liver cirrhosis with or without hepatocellular carcinoma.

METHODS

A blood sample was collected once from patients with cirrhosis alone (n = 34) or cirrhosis and hepatocellular carcinoma (n = 46) and healthy controls (n = 27) for assessing levels of endothelial progenitor cells and vascular endothelial growth factor. Blood cells staining positive for CD34/CD133/KDR using flow cytometry were characterized as endothelial progenitor cells. Plasma vascular endothelial growth factor was quantified by ELISA.

RESULTS

The levels of CD34/KDR-positive endothelial progenitor cells, CD133/KDR-positive endothelial progenitor cells, and vascular endothelial growth factor were higher in patients with cirrhosis ± hepatocellular carcinoma than in healthy controls (P = 0.017, P < 0.001 and P < 0.001, respectively). The levels of endothelial progenitor cells and vascular endothelial growth factor did not show statistical difference according to Child-Turcotte-Pugh class. There was a moderately significant correlation between vascular endothelial growth factor levels and hepatocellular carcinoma stage (ρ = 0.464, P = 0.001). Smoking, ascites, and portal vein thrombosis were independently related to lower levels of circulating CD34/KDR-positive endothelial progenitor cells, higher levels of CD133/KDR-positive endothelial progenitor cells, and higher levels of vascular endothelial growth factor, respectively (P = 0.041, P = 0.023, and P < 0.001, respectively).

CONCLUSION

Circulating endothelial progenitor cells and plasma vascular endothelial growth factor levels were higher in patients with liver cirrhosis ± hepatocellular carcinoma compared to healthy controls. The increase in endothelial progenitor cells and vascular endothelial growth factor may have a possible role in the development of complications, especially ascites and portal vein thrombosis, or in progression of hepatocellular carcinoma.

Hepatic pathology and altered gene transcription in a murine model of acid ceramidase deficiency

Farber disease (FD) is a rare lysosomal storage disorder (LSD) characterized by systemic ceramide accumulation caused by a deficiency in acid ceramidase (ACDase). In its classic form, FD manifests with painful lipogranulomatous nodules in extremities and joints, respiratory complications, and neurological involvement. Hepatosplenomegaly is commonly reported, and severe cases of FD cite liver failure as a cause of early death. Mice homozygous for an orthologous patient mutation in the ACDase gene (Asah1^P361R/P361R) recapitulate the classical form of human FD. In this study, we demonstrate impaired liver function and elevation of various liver injury markers in Asah1^P361R/P361R mice as early as 5 weeks of age. Histopathology analyses demonstrated significant formation and recruitment of foamy macrophages, invasion of neutrophils, progressive tissue fibrosis, increased cell proliferation and death, and significant storage pathology within various liver cell types. Lipidomic analyses revealed alterations to various lipid concentrations in both serum and liver tissue. A significant accumulation of ceramide and other sphingolipids in both liver and hepatocytes was noted. Sphingolipid acyl chains were also altered, with an increase in long acyl chain sphingolipids coinciding with a decrease in ultra-long acyl chains. Hepatocyte transcriptome analyses revealed significantly altered gene transcription. Molecular pathways related to inflammation were found activated, and molecular pathways involved in lipid metabolism were found deactivated. Altered gene transcription within the sphingolipid pathway itself was also observed. The data presented herein demonstrates that deficiency in ACDase results in liver pathology as well as sphingolipid and gene transcription profile changes that lead to impaired liver function.

HIV and the liver

Among individuals with HIV infection, liver disease remains an important cause of morbidity and mortality, even with the availability of agents that cure hepatitis C infection and suppress hepatitis B replication. The causes of liver disease are multifaceted and continue to evolve as the population ages and new etiologies arise. Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis and hepatitis viruses such as A, D, and E have emerged even as hepatitis C has receded. Newer antiretroviral agents may increase risk of weight gain and subsequent fatty infiltration, and prior use of nucleotide-based therapies may continue to impact liver health. Several barriers including economics, social stigma, and psychiatric disease impact identification of liver disease, as well as management and treatment interventions. Hepatocellular carcinoma is emerging as a more common and late-diagnosed complication in those with HIV infection and liver disease.

TCF12 promotes the tumorigenesis and metastasis of hepatocellular carcinoma via upregulation of CXCR4 expression

TCF12, which is known to be involved in the regulation of cell growth and differentiation, has been reported to function as an oncogene or a tumor suppressor gene in the progression of various malignant tumors. However, its function and molecular mechanism in hepatocellular carcinoma (HCC) remain unclear.

Methods: Stable ectopic TCF12 expression or knockdown in HCC cell lines was established by lentiviral infection. Then, MTT, colony formation, migration, invasion and HUVECs tube formation assays as well as an orthotopic xenograft model were used to investigate the biologic function of TCF12 in HCC cells in vitro and in vivo. Subsequently, RNA-Seq analysis was utilized to explore the target genes regulated by TCF12. RT-qPCR, western blotting, a dual-luciferase reporter assay, Ch-IP, CHIP-Seq and functional rescue experiments were used to confirm the target gene regulated by TCF12. Finally, RT-qPCR, western blot and immunohistochemical (IHC) staining were performed to detect the expression level of TCF12 and to analyze the correlation of TCF12 with downstream genes as well as the clinical significance of TCF12 in human primary HCC.

Results: Our functional studies revealed that stable overexpression of TCF12 in human HCC cells enhanced cell proliferation, migration and invasion in vitro and in vivo, whereas knockdown of TCF12 showed opposing effects. Mechanistically, CXCR4 was a downstream target of TCF12, and TCF12 directly bound to the CXCR4 promoter to regulate its expression. Moreover, CXCR4, with its ligand CXCL12, played a critical role in tumor progression induced by TCF12 via activation of the MAPK/ERK and PI3K/AKT signaling pathways. Clinically, IHC analysis revealed that TCF12 was significantly associated with poor survival of HCC patients and that TCF12 expression was closely correlated with CXCR4 expression in primary HCC tissues.

Conclusion: Our findings are the first to indicate that TCF12 could promote the tumorigenesis and progression of HCC mainly by upregulating CXCR4 expression and is a prognostic indicator for patients with HCC.

Transplanted adult human hepatic stem/progenitor cells prevent histogenesis of advanced hepatic fibrosis in mice induced by carbon tetrachloride

Transplantation of adult human hepatic stem/progenitor cells (hHSPCs) has been considered as an alternative therapy, replacing donor liver transplantation to treat liver cirrhosis. This study assessed the antifibrotic effects of hHSPCs in mice with fibrosis induced by carbon tetrachloride (CCl₄) and examined the actions of hHSPCs on the fibrogenic activity of human hepatic stellate cells (HSCs) in a coculture system. Isolated hHSPCs expressed stem/progenitor cell phenotypic markers. Mice were given CCl₄ (twice weekly for 7 weeks) and hHSPC transplantation weekly. CCl₄ induced advanced fibrosis (bridging fibrosis and cirrhosis) in mice, which was prevented by hHSPC transplantation. The liver of hHSPC-transplanted mice showed only occasional short septa and focal parenchymal fibrosis, and a 50% reduction in hepatic collagen, assessed by Sirius red stain histomorphometry. Moreover, the proteins for α-smooth muscle actin (α-SMA) and collagen I were decreased. While α-SMA, collagen α1(I), and tissue inhibitor of metalloproproteinase-1 mRNAs were decreased, matrix metalloproteinase (MMP)-1 mRNA was increased, consistent with decreased fibrogenesis. MMP-2 and transforming growth factor-β were not affected. Alanine aminotransferase and aspartate aminotransferase were lower, suggesting improvement of liver function/damage. In coculture, hHSPCs elicited changes of α-SMA and fibrogenic molecules in HSCs similar to those observed in vivo, providing evidence for a functional link between hHSPCs and HSCs. A decreased HSC proliferation was noted. Thus, transplantation of hHSPCs prevents histogenesis of advanced liver fibrosis caused by CCl₄. hHSPCs mediate downregulation of HSC activation coincident with modulation of fibrogenic molecule expression, leading to suppression of fibrogenesis both in vivo and in vitro.

HIV-1 Protein gp120 Induces Mouse Lung Fibroblast-to-Myofibroblast Transdifferentiation via CXCR4 Activation

BACKGROUND

Individuals with HIV have ∼2-fold increased risk of developing pulmonary fibrosis. The mechanism(s) by which this occurs has yet to be determined. HIV-1 protein gp120 activates CXCR4 in the lymphocyte, promoting a variety of intracellular signaling pathways including those common to TGFβ1 associated with lung fibroblast-to-myofibroblast transdifferentiation. We hypothesized that gp120 promotes pulmonary fibrotic changes via activation of CXCR4 in the lung fibroblast.

METHODS

Mouse primary lung fibroblasts (PLFs) were cultured ± gp120, then analyzed for α-SMA expression and stress fiber formation. In parallel, PLFs were cultured ± gp120 ± AMD3100 (a CXCR4 antagonist), and α-SMA, pan and phospho-Akt, and total and phospho-MAPK (or ERK1/2) protein expression was quantified. Finally, lungs and PLFs from wild-type and HIV-1 transgenic mice were analyzed for hydroxyproline and α-SMA content.

RESULTS

gp120 treatment increased α-SMA expression and myofibroblast differentiation in PLFs. gp120 treatment activated phosphorylation of ERK1/2, but not PI3K-Akt. Pretreatment with AMD3100 inhibited gp120-induced ERK1/2 phosphorylation and gp120-induced α-SMA expression. In parallel, there was a significant increase in hydroxyproline content in lungs from older HIV-1 transgenic mice and a >3-fold increase in α-SMA expression in PLFs isolated from HIV-1 transgenic mice.

CONCLUSIONS

gp120 induces α-SMA expression and fibroblast-to-myofibroblast transdifferentiation by activating the CXCR4-ERK1/2 signaling pathway in mouse PLFs. Lungs of older HIV-1 transgenic mice contain higher hydroxyproline content and their PLFs have a striking increase in α-SMA expression. These results suggest a mechanism by which individuals with HIV are at increased risk of developing pulmonary fibrotic changes as they age.

Circulating levels of CXCL11 and CXCL12 are biomarkers of cirrhosis in patients with chronic hepatitis C infection

BACKGROUND & AIMS

The chemokines CXCL10 (interferon ϒ-inducible protein 10 [IP-10]), CXCL11 (Human interferon inducible T cell alpha chemokine [I-TAC]), and CXCL12 (stromal cell derived factor 1 [SDF-1]) contribute to cell recruitment, migration, activation, and homing in liver diseases and their serum levels have been shown to be associated with the degree of liver inflammation or fibrosis in various etiologies. However, the data may be contradictory or insufficient, particularly for CXCL12, in the field of chronic HCV infection. Here, we aimed to provide evidence for these chemokines as biomarkers for chronic HCV infection.

METHODS

We analyzed the serum concentration of the three chemokines in healthy donors (n = 39) and patients (n = 87) with chronic HCV infection. Chemokine serum levels were compared to the stage of liver inflammation and fibrosis obtained from liver biopsies.

RESULTS

Serum CXCL10 and CXCL11 levels were higher at advanced stages of liver inflammation than at earlier stages, but the results were only of medium significance. Both serum CXCL11 and CXCL12 levels were significantly higher in cirrhotic patients than those with low or medium stages of fibrosis. The AUROCs were 0.8167 and 0.8574, respectively, for the diagnosis of cirrhotic patients.

CONCLUSION

These data provide evidence for the value of CXCL10, CXCL11, and CXCL12 as biomarkers of liver inflammation and fibrosis during chronic HCV infection. Serum CXCL10 and CXCL11 levels were associated with liver inflammation, but the level of significance was insufficient. However, serum CXCL11 and CXCL12 levels were elevated in cirrhotic patients, showing equivalent diagnostic accuracy as the existing established single serum fibrosis markers or algorithms.

Fibroinflammatory Liver Injuries as Preneoplastic Condition in Cholangiopathies

The cholangipathies are a class of liver diseases that specifically affects the biliary tree. These pathologies may have different etiologies (genetic, autoimmune, viral, or toxic) but all of them are characterized by a stark inflammatory infiltrate, increasing overtime, accompanied by an excess of periportal fibrosis. The cellular types that mount the regenerative/reparative hepatic response to the damage belong to different lineages, including cholagiocytes, mesenchymal and inflammatory cells, which dynamically interact with each other, exchanging different signals acting in autocrine and paracrine fashion. Those messengers may be proinflammatory cytokines and profibrotic chemokines (IL-1, and 6; CXCL1, 10 and 12, or MCP-1), morphogens (Notch, Hedgehog, and WNT/β-catenin signal pathways) and finally growth factors (VEGF, PDGF, and TGFβ, among others). In this review we will focus on the main molecular mechanisms mediating the establishment of a fibroinflammatory liver response that, if perpetuated, can lead not only to organ dysfunction but also to neoplastic transformation. Primary Sclerosing Cholangitis and Congenital Hepatic Fibrosis/Caroli’s disease, two chronic cholangiopathies, known to be prodrome of cholangiocarcinoma, for which several murine models are also available, were also used to further dissect the mechanisms of fibroinflammation leading to tumor development.

A changing paradigm: management and treatment of the HCV/HIV-co-infected patient

Hepatitis C virus (HCV) treatment in HIV/HCV co-infected individuals has renewed relevance given the ongoing opioid crisis and rise of new HIV and HCV infections associated with injection drug use. Patients co-infected with HIV and HCV demonstrate increased rates of hepatic fibrosis, progression to liver failure, and liver-related mortality. HIV co-infection does not impact outcomes of current HCV treatments, and patients should be treated the same as HCV mono-infected persons, though attention to drug:drug interactions is required. In this review, we discuss the mechanisms mediating injury to the liver in HIV mono-infection and HIV/HCV co-infection, and present the landmark trials of HCV treatment in HIV-infected individuals.

Soluble CD74 Reroutes MIF/CXCR4/AKT-Mediated Survival of Cardiac Myofibroblasts to Necroptosis

Background Although macrophage migration inhibitory factor ( MIF ) has been demonstrated to mediate cardioprotection in ischemia/reperfusion injury and antagonize fibrotic effects through its receptor, CD 74, the function of the soluble CD 74 receptor ectodomain ( sCD 74) and its interaction with circulating MIF have not been explored in cardiac disease. Methods and Results Cardiac fibroblasts were isolated from hearts of neonatal mice and differentiated into myofibroblasts. Co-treatment with recombinant MIF and sCD 74 induced cell death ( P<0.001), which was mediated by receptor-interacting serine/threonine-protein kinase ( RIP) 1/ RIP 3-dependent necroptosis ( P=0.0376). This effect was specific for cardiac fibroblasts and did not affect cardiomyocytes. Gene expression analyses using microarray and RT - qPCR technology revealed a 4-fold upregulation of several interferon-induced genes upon co-treatment of myofibroblasts with sCD 74 and MIF (Ifi44: P=0.011; Irg1: P=0.022; Clec4e: P=0.011). Furthermore, Western blot analysis confirmed the role of sCD 74 as a modulator of MIF signaling by diminishing MIF -mediated protein kinase B ( AKT) activation ( P=0.0197) and triggering p38 activation ( P=0.0641). We obtained evidence that sCD 74 inhibits MIF -mediated survival pathway through the C-X-C chemokine receptor 4/ AKT axis, enabling the induction of CD 74-dependent necroptotic processes in cardiac myofibroblasts. Preliminary clinical data revealed a lowered sCD 74/ MIF ratio in heart failure patients (17.47±10.09 versus 1.413±0.6244). Conclusions These findings suggest that treatment of cardiac myofibroblasts with sCD 74 and MIF induces necroptosis, offering new insights into the mechanism of myofibroblast depletion during scar maturation. Preliminary clinical data provided first evidence about a clinical relevance of the sCD 74/ MIF axis in heart failure, suggesting that these proteins may be a promising target to modulate cardiac remodeling and disease progression in heart failure.

Chronic Hyperglycaemia Induced Alterations of Hepatic Stellate Cells Differ from the Effect of TGFB1, and Point toward Metabolic Stress

The deleterious effect of hyperglycemia on the biology of the liver is supported by clinical evidence. It can promote the development of fatty liver, liver fibrosis, even liver cancer as complication of diabetes mellitus. As liver fibrosis is the consequence of hepatic stellate cell (HSC) activation, the questions were addressed whether alterations induced by high glucose concentration are directly related to TGFB1 effect, or other mechanisms are activated. In order to obtain information on the response of HSC for high glucose, LX-2 cells (an immortalized human HSC cell lineage) were cultured in 15.3 mM glucose containing medium for 21 days. The effect of glucose was compared to that of TGFB1. Our data revealed that chronic exposure of high glucose concentration initiated profound alteration of LX-2 cells and the effect is different from those observed upon interaction with TGFB1. Whereas TGFB1 induced the production of extracellular matrix proteins, high glucose exposure resulted in decreased MMP2 activity, retardation of type I collagen in the endoplasmic reticulum, with decreased pS6 expression, pointing to development of endoplasmic stress and sequestration of p21^CIP1/WAF1 in the cytoplasm which can promote the proliferation of LX2 cells.

Curcumin protects against hepatic stellate cells activation and migration by inhibiting the CXCL12/CXCR4 biological axis in liver fibrosis：A study in vitro and in vivo

The C-X-C motif chemokine 12/C-X-C chemokine receptor type 4 (CXCL12/ CXCR4) biological axis plays an important role in the pathogenesis of liver fibrosis. Curcumin is known to have an anti-fibrosis effect, but the specific mechanism needs to be elucidated. There is currently no evidence illustrating a connection between curcumin and the CXCL12/CXCR4 axis in liver fibrosis. Here, we investigated the contribution of curcumin on CXCL12/ CXCR4 biological axis in liver fibrosis. Our results showed that curcumin remarkably improved hepatic function and liver fibrosis, and the effects are similar as silymarin. The alleviation of liver fibrosis with curcumin treatment was associated with a reduction of CXCL12, CXCR4, α-SMA and RhoA. In addition, curcumin markedly inhibited the proliferation and migration of HSC-T6 cells. This study indicates that curcumin could protect against hepatic stellate cells activation and migration by inhibiting the CXCL12/CXCR4 biological axis in liver fibrosis.

Combined delivery of sorafenib and a MEK inhibitor using CXCR4-targeted nanoparticles reduces hepatic fibrosis and prevents tumor development

Liver damage and fibrosis are precursors of hepatocellular carcinoma (HCC). In HCC patients, sorafenib—a multikinase inhibitor drug—has been reported to exert anti-fibrotic activity. However, incomplete inhibition of RAF activity by sorafenib may also induce paradoxical activation of the mitogen-activated protein kinase (MAPK) pathway in malignant cells. The consequence of this effect in non-malignant disease (hepatic fibrosis) remains unknown. This study aimed to examine the effects of sorafenib on activated hepatic stellate cells (HSCs), and develop effective therapeutic approaches to treat liver fibrosis and prevent cancer development.

Methods: We first examined the effects of sorafenib in combination with MEK inhibitors on fibrosis pathogenesis in vitro and in vivo. To improve the bioavailability and absorption by activated HSCs, we developed CXCR4-targeted nanoparticles (NPs) to co-deliver sorafenib and a MEK inhibitor to mice with liver damage.

Results: We found that sorafenib induced MAPK activation in HSCs, and promoted their myofibroblast differentiation. Combining sorafenib with a MEK inhibitor suppressed both paradoxical MAPK activation and HSC activation in vitro, and alleviated liver fibrosis in a CCl₄-induced murine model of liver damage. Furthermore, treatment with sorafenib/MEK inhibitor-loaded CXCR4-targeted NPs significantly suppressed hepatic fibrosis progression and further prevented fibrosis-associated HCC development and liver metastasis.

Conclusions: Our results show that combined delivery of sorafenib and a MEK inhibitor via CXCR4-targeted NPs can prevent activation of ERK in activated HSCs and has anti-fibrotic effects in the CCl₄-induced murine model. Targeting HSCs represents a promising strategy to prevent the development and progression of fibrosis-associated HCC.

Intrahepatic MicroRNA Profile of Liver Transplant Recipients with Hepatitis C Virus Co-Infected with Human Immunodeficiency Virus

BACKGROUND In patients with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) co-infection, HIV can modulate HCV replication and immune response as well as accelerate liver fibrosis. The role of miRNA in HIV/HCV co-infection is not fully elucidated. The aim of this study was to examine the differential expression of miRNAs in the liver. MATERIAL AND METHODS Thirteen patients who had undergone a liver transplant (7 HCV-infected and 6 HIV/HCV-co-infected patients) were examined using a miRNA array containing 1347 human miRNAs. To confirm the microarray results, data for 20 patients (10 HCV-infected and 10 HIV/HCV-co-infected) were validated using real-time polymerase chain reaction probing for miR101b, miR149, and miR200c. This miRNA was selected based on microarray results and its biological significance in liver fibrosis. RESULTS Microarray analysis revealed 22 miRNAs that were differentially expressed in the HIV/HCV-co-infected group compared to the HCV-infected group (p<0.05). The expression of miR-101b and miR149 was significantly decreased in the HIV/HCV-co-infected group compared to that in the HCV-infected group (miR101b, 0.103±0.09 vs. 0.0157±0.0093, p=0.007; miR149, 0.152±0.159 vs. 0.0192±0.015, p=0.025). CONCLUSIONS HIV/HCV co-infection may promote liver fibrosis by modulating miRNA expression.

Serum matrix metalloproteinase-1 level represents disease activity as opposed to fibrosis in patients with histologically proven nonalcoholic steatohepatitis

Background/Aims

Nonalcoholic steatohepatitis (NASH) is prevalent in both economically developed and developing countries. Twenty percent of NASH progresses to cirrhosis with/without hepatocellular carcinoma, and there is an urgent need to find biomarkers for early diagnosis and monitoring progression of the disease. Using immunohistochemical and immunoelectron microscopic examination we previously reported that expression of matrix metalloproteinase-1 (MMP-1) increased in monocytes, Kupffer cells and hepatic stellate cells in early stage NASH. The present study investigated whether serum MMP-1 levels reflect disease activity and pharmaceutical effects in NASH patients.

Methods

We measured the serum levels of MMPs, tissue inhibitors of metalloproteinases (TIMPs), and several cytokines/chemokines in patients with histologically proven early and advanced stages of NASH and compared them with those in healthy controls.

Results

Serum MMP-1 levels in stage 1 fibrosis, but not in the more advanced fibrosis stages, were significantly higher than in healthy controls (P=0.019). There was no correlation between serum MMP-1 level and fibrosis stage. Serum MMP- 1 levels in NASH patients represented disease activity estimated by serum aminotransferase values during the follow-up period. In contrast, MMP-2, MMP-9 and TIMPs did not change with disease activity. Consistent with the finding that MMP-1 is expressed predominantly in monocytes and Kupffer cells, serum levels of monocyte chemotactic protein-1 and granulocyte-colony stimulating factor were significantly increased in NASH with stage 1 fibrosis.

Conclusions

These results suggest that serum MMP-1 levels represent disease activity and may serve as a potential biomarker for monitoring the progression of NASH.

The role of vitamin D in hepatic metastases from colorectal cancer

Colorectal cancer (CRC) represents a significant health burden worldwide, comprising approximately 10% of annual cancer cases globally. Hepatic metastases are the most common site of CRC metastasis, and are the leading cause of death in CRC patients. There is strong epidemiologic evidence for an inverse association between vitamin D status and risk of CRC; however, the role of vitamin D in the natural history of liver metastases has not yet been investigated. Several researchers have proposed hallmarks of metastases; crucially, metastases can be blocked by interrupting just one rate-limiting step. Vitamin D status has been implicated in each proposed hallmark of metastasis. The aim of this review is to examine the potential role for vitamin D in reducing the development of hepatic metastases from CRC and outline the candidate mechanisms by which vitamin D may mediate these effects. The results of ongoing randomised intervention trials are eagerly awaited to determine whether addressing vitamin D insufficiency in CRC patients could reduce the occurrence of liver metastases, and the consequent morbidity and mortality.

Effects of Therapy with Maraviroc on the Carotid Intima Media Thickness in HIV-1/HCV Co-infected Patients

AIM

To evaluate, in human immunodeficiency virus-hepatitis C virus co-infected patients, the impact of C-C chemokine receptor type 5 (CCR5) antagonist maraviroc-based antiretroviral therapy on the carotid intima media thickness and on atheromasic plaques.

PATIENTS AND METHODS

In this pilot prospective study, 12 HIV-HCV co-infected patients underwent color-Doppler ultrasonography before and 48 weeks after switching to a dual therapy based on maraviroc plus protease inhibitors boosted with ritonavir. Changes of intima media thickness, inflammatory and endothelial adhesion biomarkers levels, Veterans Aging Cohort Study index and Framingham risk score were evaluated.

RESULTS

At baseline 11 (91.6%) patients showed pathological ultrasonographic findings. After 48 weeks, two patients showed an amelioration of intima media thickness. Of the remaining patients with plaques, four showed a reduction of the previously diagnosed plaque; no patients worsened.

CONCLUSION

Our data suggest that CCR5 inhibition could reduce the development of atherosclerosis especially in the non-calcific stage and could play an important role in the blockade of atheromasic plaque progression.

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

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

Characterization of gene expression profiles in HBV-related liver fibrosis patients and identification of ITGBL1 as a key regulator of fibrogenesis

Although hepatitis B virus (HBV) infection is the leading cause of liver fibrosis (LF), the mechanisms underlying liver fibrotic progression remain unclear. Here, we investigated the gene expression profiles of HBV-related LF patients. Whole genome expression arrays were used to detect gene expression in liver biopsy samples from chronically HBV infected patients. Through integrative data analysis, we identified several pathways and key genes involved in the initiation and exacerbation of liver fibrosis. Weight gene co-expression analysis revealed that integrin subunit β-like 1 (ITGBL1) was a key regulator of fibrogenesis. Functional experiments demonstrated that ITGBL1 was an upstream regulator of LF via interactions with transforming growth factor β1. In summary, we investigated the gene expression profiles of HBV-related LF patients and identified a key regulator ITGBL1. Our findings provide a foundation for future studies of gene functions and promote the development of novel antifibrotic therapies.

Joint Profiling of miRNAs and mRNAs Reveals miRNA Mediated Gene Regulation in the Göttingen Minipig Obesity Model

Obesity and its comorbidities are an increasing challenge for both affected individuals and health care systems, worldwide. In obese individuals, perturbation of expression of both protein-coding genes and microRNAs (miRNA) are seen in obesity-relevant tissues (i.e. adipose tissue, liver and skeletal muscle). miRNAs are small non-coding RNA molecules which have important regulatory roles in a wide range of biological processes, including obesity. Rodents are widely used animal models for human diseases including obesity. However, not all research is applicable for human health or diseases. In contrast, pigs are emerging as an excellent animal model for obesity studies, due to their similarities in their metabolism, their digestive tract and their genetics, when compared to humans. The Göttingen minipig is a small sized easy-to-handle pig breed which has been extensively used for modeling human obesity, due to its capacity to develop severe obesity when fed ad libitum. The aim of this study was to identify differentially expressed of protein-coding genes and miRNAs in a Göttingen minipig obesity model. Liver, skeletal muscle and abdominal adipose tissue were sampled from 7 lean and 7 obese minipigs. Differential gene expression was investigated using high-throughput quantitative real-time PCR (qPCR) on 90 mRNAs and 72 miRNAs. The results revealed de-regulation of several obesity and inflammation-relevant protein-coding genes and miRNAs in all tissues examined. Many genes that are known to be de-regulated in obese humans were confirmed in the obese minipigs and several of these genes have target sites for miRNAs expressed in the opposing direction of the gene, confirming miRNA-mediated regulation in obesity. These results confirm the translational value of the pig for human obesity studies.

Interleukin-15 receptor α on hepatic stellate cells regulates hepatic fibrogenesis in mice

BACKGROUND & AIMS

Interleukin-15 (IL-15) and its high affinity receptor interleukin-15 receptor alpha (IL-15Rα) are widely expressed in immune cells and hepatic resident cells. IL-15 signaling has important functions in homeostasis of natural killer (NK), natural killer T (NKT) and cytotoxic T (CD8(+) T) cells, and in liver regeneration. We hypothesized that IL-15 has a protective role in liver fibrosis progression by maintaining NK cell homeostasis.

METHODS

Fibrosis was induced using two mechanistically distinct models. Congenic bone marrow transplantation was used to evaluate the contribution of IL-15 signaling from various compartments to NK, CD8(+) T and NKT cell homeostasis and fibrogenesis. The gene expression profile of hepatic stellate cell (HSC) from IL-15Rα knockout (IL-15RαKO) mice and wild-type mice were captured using microarray analysis and validated in isolated HSC. Quantitative real-time PCR was used to assess repressors of collagen transcription.

RESULTS

IL-15RαKO mice exhibited more fibrosis in both models. IL-15 signaling from specific types of hepatic cells had divergent roles in maintaining liver NK, CD8(+) T and NKT cells, with a direct and protective role on radio-resistant non-parenchymal cells beyond the control of NK homeostasis. HSCs isolated from IL-15RαKO mice demonstrated upregulation of collagen production. Finally, IL-15RαKO HSC with or without transforming growth factor beta (TGF-β) stimulation exhibited increased expression of fibrosis markers and decreased collagen transcription repressors expression.

CONCLUSIONS

IL-15Rα signaling has a direct anti-fibrotic effect independent of preserving NK homeostasis. These findings establish a rationale to further explore the anti-fibrotic potential of enhancing IL-15 signaling in HSCs.

LAY SUMMARY

We investigated how a cellular protein, Interleukin-15 (IL-15), decreases the amount of scar tissue that is formed upon liver injury. We found that IL-15 and its receptor decrease the amount of scar tissue that is created by specialized liver cells (called stellate cells) and increase the number of a specific subgroup of immune cells (natural killer cells) that are known to eliminate stellate cells.

TRANSCRIPT PROFILING ACCESSION NUMBER

GSE45612, GSE 68001 and GSE 25097.

Stromal cell-derived factor-1 (SDF-1) as a target in liver diseases

The chemokine stromal cell-derived factor-1 (SDF-1) or CXCL12 is constitutively expressed in healthy liver. However, its expression increases following acute or chronic liver injury. Liver sinusoidal endothelial cells (LSEC), hepatic stellate cells (HSC), and malignant hepatocytes are important sources of SDF-1/CXCL12 in liver diseases. CXCL12 is able to activate two chemokine receptors with different downstream signaling pathways, CXCR4 and CXCR7. CXCR7 expression is relevant on LSEC, while HSC, mesenchymal stem cells, and tumor cells mainly respond via CXCR4. Here, we summarize recent developments in the field of liver diseases involving this chemokine and its receptors. SDF-1-dependent signaling contributes to modulating acute liver injury and subsequent tissue regeneration. By activating HSC and recruiting mesenchymal cells from bone marrow, CXCL12 can promote liver fibrosis progression, while CXCL12-CXCR7 interactions endorse proregenerative responses in chronic injury. Moreover, the SDF-1 pathway is linked to development of hepatocellular carcinoma (HCC) by promoting tumor growth, angiogenesis, and HCC metastasis. High hepatic CXCR4 expression has been suggested as a biomarker indicating poor prognosis of HCC patients. Tumor-infiltrating myeloid-derived suppressor cells (MDSC) also express CXCR4 and migrate toward CXCL12. Thus CXCL12 inhibition might not only directly block HCC growth but also modulate the tumor microenvironment (angiogenesis, MDSC), thereby sensitizing HCC patients to conventional or emerging novel cancer therapies (e.g., sorafenib, regorafenib, nivolumab, pembrolizumab). We herein summarize the current knowledge on the complex interplay between CXCL12 and CXCR4/CXCR7 in liver diseases and discuss approaches on the therapeutic targeting of these axes in hepatitis, fibrosis, and liver cancer.

HIV and HCV Co-Culture Promotes Profibrogenic Gene Expression through an Epimorphin-Mediated ERK Signaling Pathway in Hepatic Stellate Cells

Accelerated fibrosis in patients co-infected with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) has been a major cause of mortality in the highly active anti-retroviral therapy (HAART) era. However, the role of co-infection in accelerating the progression of liver fibrosis, particularly with regard to the effects of co-infection on hepatic stellate cells (HSCs), remains unclear. We hypothesized that HIV and HCV induce liver fibrosis synergistically by altering the regulation of epimorphin production, and thereby indirectly alter HSC function. Here, we examined the effects of epimorphin on HSC proliferation and invasion, and the changes in fibrogenesis-related gene activity in HSCs (LX2) in the presence of inactivated CXCR4-tropic HIV and HCV (JFH1). The combination of HIV and HCV significantly increased epimorphin expression, which increased the proliferation and invasion capabilities of HSCs. Epimorphin also induced the expression of profibrogenic tissue inhibitor of metalloproteinase 1 (TIMP1) in an extracellular signal-regulated kinase (ERK)-dependent manner. These data indicated that the effects of HIV/HCV co-infection on hepatic fibrosis might be mediated in part by EPM. Strategies to limit the expression of EPM might represent a novel therapeutic approach to prevent the progression of hepatic fibrosis during HIV/HCV co-infection.

Dual-Functional Nanoparticles Targeting CXCR4 and Delivering Antiangiogenic siRNA Ameliorate Liver Fibrosis

The progression of liver fibrosis, an intrinsic response to chronic liver injury, is associated with hepatic hypoxia, angiogenesis, abnormal inflammation, and significant matrix deposition, leading to the development of cirrhosis and hepatocellular carcinoma (HCC). Due to the complex pathogenesis of liver fibrosis, antifibrotic drug development has faced the challenge of efficiently and specifically targeting multiple pathogenic mechanisms. Therefore, CXCR4-targeted nanoparticles (NPs) were formulated to deliver siRNAs against vascular endothelial growth factor (VEGF) into fibrotic livers to block angiogenesis during the progression of liver fibrosis. AMD3100, a CXCR4 antagonist that was incorporated into the NPs, served dual functions: it acted as a targeting moiety and suppressed the progression of fibrosis by inhibiting the proliferation and activation of hepatic stellate cells (HSCs). We demonstrated that CXCR4-targeted NPs could deliver VEGF siRNAs to fibrotic livers, decrease VEGF expression, suppress angiogenesis and normalize the distorted vessels in the fibrotic livers in the carbon tetrachloride (CCl4) induced mouse model. Moreover, blocking SDF-1α/CXCR4 by CXCR4-targeted NPs in combination with VEGF siRNA significantly prevented the progression of liver fibrosis in CCl4-treated mice. In conclusion, the multifunctional CXCR4-targeted NPs delivering VEGF siRNAs provide an effective antifibrotic therapeutic strategy.