Hepatic stellate cells express the low affinity nerve growth factor receptor p75 and undergo apoptosis in response to nerve growth factor stimulation

Nerve Growth Factor and the Role of Inflammation in Tumor Development

Nerve growth factor (NGF) plays a dual role both in inflammatory states and cancer, acting both as a pro-inflammatory and oncogenic factor and as an anti-inflammatory and pro-apoptotic mediator in a context-dependent way based on the signaling networks and its interaction with diverse cellular components within the microenvironment. This report aims to provide a summary and subsequent review of the literature on the role of NGF in regulating the inflammatory microenvironment and tumor cell growth, survival, and death. The role of NGF in inflammation and tumorigenesis as a component of the inflammatory system, its interaction with the various components of the respective microenvironments, its ability to cause epigenetic changes, and its role in the treatment of cancer have been highlighted in this paper.

A Quick Guide to CAF Subtypes in Pancreatic Cancer

Pancreatic cancer represents one of the most desmoplastic malignancies and is characterized by an extensive deposition of extracellular matrix. The latter is provided by activated cancer-associated fibroblasts (CAFs), which are abundant cells in the pancreatic tumor microenvironment. Many recent studies have made it clear that CAFs are not a singular cellular entity but represent a multitude of potentially dynamic subgroups that affect tumor biology at several levels. As mentioned before, CAFs significantly contribute to the fibrotic reaction and the biomechanical properties of the tumor, but they can also modulate the local immune environment and the response to targeted, chemo or radiotherapy. As the number of known and emerging CAF subgroups is steadily increasing, it is becoming increasingly difficult to keep up with these developments and to clearly discriminate the cellular subsets identified so far. This review aims to provide a helpful overview that enables readers to quickly familiarize themselves with field of CAF heterogeneity and to grasp the phenotypic, functional and therapeutic distinctions of the various stromal subpopulations.

Neurotrophin signaling is a central mechanism of salivary dysfunction after irradiation that disrupts myoepithelial cells

The mechanisms that prevent regeneration of irradiated (IR) salivary glands remain elusive. Bulk RNAseq of IR versus non-IR human salivary glands showed that neurotrophin signaling is highly disrupted post-radiation. Neurotrophin receptors (NTRs) were significantly upregulated in myoepithelial cells (MECs) post-IR, and single cell RNAseq revealed that MECs pericytes, and duct cells are the main sources of neurotrophin ligands. Using two ex vivo models, we show that nerve growth factor (NGF) induces expression of MEC genes during development, and upregulation of NTRs in adult MECs is associated with stress-induced plasticity and morphological abnormalities in IR human glands. As MECs are epithelial progenitors after gland damage and are required for proper acinar cell contraction and secretion, we propose that MEC-specific upregulation of NTRs post-IR disrupts MEC differentiation and potentially impedes the ability of the gland to regenerate.

Histopathological growth patterns of liver metastasis: updated consensus guidelines for pattern scoring, perspectives and recent mechanistic insights

The first consensus guidelines for scoring the histopathological growth patterns (HGPs) of liver metastases were established in 2017. Since then, numerous studies have applied these guidelines, have further substantiated the potential clinical value of the HGPs in patients with liver metastases from various tumour types and are starting to shed light on the biology of the distinct HGPs. In the present guidelines, we give an overview of these studies, discuss novel strategies for predicting the HGPs of liver metastases, such as deep-learning algorithms for whole-slide histopathology images and medical imaging, and highlight liver metastasis animal models that exhibit features of the different HGPs. Based on a pooled analysis of large cohorts of patients with liver-metastatic colorectal cancer, we propose a new cut-off to categorise patients according to the HGPs. An up-to-date standard method for HGP assessment within liver metastases is also presented with the aim of incorporating HGPs into the decision-making processes surrounding the treatment of patients with liver-metastatic cancer. Finally, we propose hypotheses on the cellular and molecular mechanisms that drive the biology of the different HGPs, opening some exciting preclinical and clinical research perspectives.

Development of human iPSC-derived quiescent hepatic stellate cell-like cells for drug discovery and in vitro disease modeling

Hepatic stellate cells (HSCs) play a central role in the progression of liver fibrosis by producing extracellular matrices. The development of drugs to suppress liver fibrosis has been hampered by the lack of human quiescent HSCs (qHSCs) and an appropriate in vitro model that faithfully recapitulates HSC activation. In the present study, we developed a culture system to generate qHSC-like cells from human-induced pluripotent stem cells (hiPSCs) that can be converted into activated HSCs in culture. To monitor the activation process, a red fluorescent protein (RFP) gene was inserted in hiPSCs downstream of the activation marker gene actin alpha 2 smooth muscle (ACTA2). Using qHSC-like cells derived from RFP reporter iPSCs, we screened a repurposing chemical library and identified therapeutic candidates that prevent liver fibrosis. Hence, hiPSC-derived qHSC-like cells will be a useful tool to study the mechanism of HSC activation and to identify therapeutic agents.

An immunohistochemical examination of cinnamon extract administration on distribution of NGF (nerve growth factor) and Trk-A (tyrosine kinase-A) receptor for diabetic rats with pancreatic tissue

BACKGROUND

The aim of this study was to investigate the administration of cinnamon extract that is known to be effective in decreasing the high blood glucose and the distribution of NGF and Trk-A receptor in pancreas with immunohistochemistry way.

METHODS

The experimental groups were defined as control, sham, cinnamon, diabetes, and diabetes-cinnamon. At the end of the experiment, the pancreatic tissue samples were obtained for the rats. The hematoxylin-eosin and triple staining were used to examine histology. The immunohistochemical methods were performed on the sections of pancreatic tissue. In all groups, the body weight and fasting blood glucose obtained from the male and female rats and the values were statistically evaluated.

RESULTS

The NGF immunoreactivity was observed in acinus, excretory pars, excretorius ducts, and islets of Langerhans for the pancreatic tissues of female and male rats in all groups. The Trk-A immunoreactivity was observed in acinus and islets of Langerhans for the pancreatic tissues of female and male rats in the control, sham, and cinnamon groups.

DISCUSSION

As a result, it was determined that the cinnamon, which is effective on blood glucose levels, has a positive effect on the NGF production in pancreas.

High-throughput injection molded microfluidic device for single-cell analysis of spatiotemporal dynamics

Single-cell level analysis of various cellular behaviors has been aided by recent developments in microfluidic technology. Polydimethylsiloxane (PDMS)-based microfluidic devices have been widely used to elucidate cell differentiation and migration under spatiotemporal stimulation. However, microfluidic devices fabricated with PDMS have inherent limitations due to material issues and non-scalable fabrication process. In this study, we designed and fabricated an injection molded microfluidic device that enables real-time chemical profile control. This device is made of polystyrene (PS), engineered with channel dimensions optimized for injection molding to achieve functionality and compatibility with single cell observation. We demonstrated the spatiotemporal dynamics in the device with computational simulation and experiments. In temporal dynamics, we observed extracellular signal-regulated kinase (ERK) activation of PC12 cells by stimulating the cells with growth factors (GFs). Also, we confirmed yes-associated protein (YAP) phase separation of HEK293 cells under stimulation using sorbitol. In spatial dynamics, we observed the migration of NIH 3T3 cells (transfected with Lifeact-GFP) under different spatiotemporal stimulations of PDGF. Using the injection molded plastic devices, we obtained comprehensive data more easily than before while using less time compared to previous PDMS models. This easy-to-use plastic microfluidic device promises to open a new approach for investigating the mechanisms of cell behavior at the single-cell level.

Disruption of myofibroblastic Notch signaling attenuates liver fibrosis by modulating fibrosis progression and regression

The phenotypic transformation of hepatic myofibroblasts (MFs) is involved in the whole process of the progression and regression of liver fibrosis. Notch signaling has been demonstrated to modulate the fibrosis. In this study, we found that Notch signaling in MFs was overactivated and suppressed with the progression and regression of hepatic fibrosis respectively, by detecting Notch signaling readouts in MFs. Moreover, we inactivated Notch signaling specifically in MFs with Sm22α^CreER-RBPj^flox/flox mice (RBPj^MF-KO), and identified that MFs-specific down-regulation of Notch signaling significantly alleviated CCl₄-induced liver fibrosis during the progression and regression. During the progression of liver fibrosis, MFs-specific blockade of Notch signaling inhibited the activation of HSCs to MFs and increases the expression of MMPs to reduce the deposition of ECM. During the regression of fibrosis, blocking Notch signaling in MFs increased the expression of HGF to promote proliferation in hepatocytes and up-regulated the expression of pro-apoptotic factors, Ngfr and Septin4, to induce apoptosis of MFs, thereby accelerating the reversal of fibrosis. Collectively, the MFs-specific disruption of Notch signaling attenuates liver fibrosis by modulating fibrosis progression and regression, which suggests a promising therapeutic strategy for liver fibrosis.

Acceleration of TAA-Induced Liver Fibrosis by Stress Exposure Is Associated with Upregulation of Nerve Growth Factor and Glycopattern Deviations

Liver fibrosis results from many chronic injuries and may often progress to cirrhosis and hepatocellular carcinoma (HCC). In fact, up to 90% of HCC arise in a cirrhotic liver. Conversely, stress is implicated in liver damage, worsening disease outcome. Hence, stress could play a role in disrupting liver homeostasis, a concept that has not been fully explored. Here, in a murine model of TAA-induced liver fibrosis we identified nerve growth factor (NGF) to be a crucial regulator of the stress-induced fibrogenesis signaling pathway as it activates its receptor p75 neurotrophin receptor (p75NTR), increasing liver damage. Additionally, blocking the NGF decreased liver fibrosis whereas treatment with recombinant NGF accelerated the fibrotic process to a similar extent than stress challenge. We further show that the fibrogenesis induced by stress is characterized by specific changes in the hepatoglycocode (increased β1,6GlcNAc-branched complex N-glycans and decreased core 1 O-glycans expression) which are also observed in patients with advanced fibrosis compared to patients with a low level of fibrosis. Our study facilitates an understanding of stress-induced liver injury and identify NGF signaling pathway in early stages of the disease, which contributes to the established fibrogenesis.

Hepatic stellate cells - from past till present: morphology, human markers, human cell lines, behavior in normal and liver pathology

Hepatic stellate cell (HSC), initially analyzed by von Kupffer, in 1876, revealed to be an extraordinary mesenchymal cell, essential for both hepatocellular function and lesions, being the hallmark of hepatic fibrogenesis and carcinogenesis. Apart from their implications in hepatic injury, HSCs play a vital role in liver development and regeneration, xenobiotic response, intermediate metabolism, and regulation of immune response. In this review, we discuss the current state of knowledge regarding HSCs morphology, human HSCs markers and human HSC cell lines. We also summarize the latest findings concerning their roles in normal and liver pathology, focusing on their impact in fibrogenesis, chronic viral hepatitis and liver tumors.

Effect of carvedilol versus propranolol on acute and chronic liver toxicity in rats

Non-selective β-blockers have largely been used for prophylaxis of bleeding from gastroesophageal varices, but their hepatic effects and their influence on the development of varices has yet to be clarified. This study examined whether carvedilol would reduce acute and chronic liver injury in rats in comparison to propranolol. Experiment (1) Investigated the effects of carvedilol (1.2 mg/kg) and propranolol (4.0 mg/kg) administered daily for 7 days by gavage on paracetamol (1500 mg/kg i.p.) -induced acute liver injury in rats. Experiment (2) Investigated the effects of carvedilol (1.2 mg/kg) and propranolol (4.0 mg/kg) by gavage daily for 8 weeks on CCl4 -induced chronic liver injury in rats. Biochemical markers and histopathology of the livers were studied. Liver perfusion studies were carried out on CCl4 treated rats. Experiment (1) Carvedilol significantly improved the functional state of the liver in paracetamol-induced acute toxic hepatitis to a greater extent than propranolol. This was evidenced by a greater reduction in elevated serum levels of ALT and AST, hepatic MDA and TNF-α, attenuation of the paracetamol-induced decrease in GSH, together with improvement in the histological architecture of the liver. Experiment (2) Carvedilol was superior to propranolol against CCl4-induced hepatic injury and fibrogenesis. It suppressed hepatic inflammation, attenuated hepatic oxidative stress, and inhibited HSC activation. Carvedilol also decreased portal perfusion pressure. These results suggest that carvedilol might be a therapeutic anti-fibrogenic candidate against hepatic fibrosis, protecting the liver from acute and chronic toxic injury, in addition to lowering portal pressure.

Cellular Heterogeneity of Pancreatic Stellate Cells, Mesenchymal Stem Cells, and Cancer-Associated Fibroblasts in Pancreatic Cancer

Pancreatic cancer is projected to become the second deadliest cancer by 2030 in the United States, and the overall five-year survival rate stands still at around 9%. The stroma compartment can make up more than 90% of the pancreatic tumor mass, contributing to the hypoxic tumor microenvironment. The dense stroma with extracellular matrix proteins can be a physical and metabolic barrier reducing therapeutic efficacy. Cancer-associated fibroblasts are a source of extracellular matrix proteins. Therefore, targeting these cells, or extracellular matrix proteins, have been considered as therapeutic strategies. However, several studies show that deletion of cancer-associated fibroblasts may have tumor-promoting effects. Cancer-associated fibroblasts are derived from a variety of different cell types, such as pancreatic stellate cells and mesenchymal stem cells, and constitute a diverse cell population consisting of several functionally heterogeneous subtypes. Several subtypes of cancer-associated fibroblasts exhibit a tumor-restraining function. This review article summarizes recent findings regarding origin and functional heterogeneity of tumor-promoting as well as tumor-restraining cancer-associated fibroblasts. A better understanding of cancer-associated fibroblast heterogeneity could provide more specific and personalized therapies for pancreatic cancer patients in the future.

Pathological Mechanisms in Diabetes of the Exocrine Pancreas: What's Known and What's to Know

The clinical significance of diabetes arising in the setting of pancreatic disease (also known as diabetes of the exocrine pancreas, DEP) has drawn more attention in recent years. However, significant improvements still need to be made in the recognition, diagnosis and treatment of the disorder, and in the knowledge of the pathological mechanisms. The clinical course of DEP is different from type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). DEP develops in patients with previous existing exocrine pancreatic disorders which damage both exocrine and endocrine parts of pancreas, and lead to pancreas exocrine insufficiency (PEI) and malnutrition. Therefore, damage in various exocrine and endocrine cell types participating in glucose metabolism regulation likely contribute to the development of DEP. Due to the limited amount of clinical and experimental studies, the pathological mechanism of DEP is poorly defined. In fact, it still not entirely clear whether DEP represents a distinct pathologic entity or is a form of T2DM arising when β cell failure is accelerated by pancreatic disease. In this review, we include findings from related studies in T1DM and T2DM to highlight potential pathological mechanisms involved in initiation and progression of DEP, and to provide directions for future research studies.

Collagen-Derived Di-Peptide, Prolylhydroxyproline (Pro-Hyp): A New Low Molecular Weight Growth-Initiating Factor for Specific Fibroblasts Associated With Wound Healing

Many cells and soluble factors are involved in the wound healing process, which can be divided into inflammatory, proliferative, and remodeling phases. Fibroblasts play a crucial role in wound healing, especially during the proliferative phase, and show heterogeneity depending on lineage, tissue distribution, and extent of differentiation. Fibroblasts from tissue stem cells rather than from healthy tissues infiltrate wounds and proliferate. Some fibroblasts in the wound healing site express the mesenchymal stem cell marker, p75NTR. In the cell culture system, fibroblasts attached to collagen fibrils stop growing, even in the presence of protein growth factors, thus mimicking the quiescent nature of fibroblasts in healthy tissues. Fibroblasts in wound healing sites proliferate and are surrounded by collagen fibrils. These facts indicate presence of new growth-initiating factor for fibroblasts attached to collagen fibrils at the wound healing site, where the collagen-derived peptide, prolyl-hydroxyproline (Pro-Hyp), is generated. Pro-Hyp triggers the growth of p75NTR-positive fibroblasts cultured on collagen gel but not p75NTR-negative fibroblasts. Thus, Pro-Hyp is a low molecular weight growth-initiating factor for specific fibroblasts that is involved in the wound healing process. Pro-Hyp is also supplied to tissues by oral administration of gelatin or collagen hydrolysate. Thus, supplementation of gelatin or collagen hydrolysate has therapeutic potential for chronic wounds. Animal studies and human clinical trials have demonstrated that the ingestion of gelatin or collagen hydrolysate enhances the healing of pressure ulcers in animals and humans and improves delayed wound healing in diabetic animals. Therefore, the low molecular weight fibroblast growth-initiating factor, Pro-Hyp, plays a significant role in wound healing and has therapeutic potential for chronic wounds.

Macrophages in the pancreas: Villains by circumstances, not necessarily by actions

Introduction

Mounting evidence suggest that macrophages play crucial roles in disease and tissue regeneration. However, despite much efforts during the past decade, our knowledge about the extent of macrophages' contribution to adult pancreatic regeneration after injury or during pancreatic disease progression is still limited. Nevertheless, it is generally accepted that some macrophage features that normally would contribute to healing and regeneration may be detrimental in pancreatic cancer. Altogether, the current literature contains conflicting reports on whether macrophages act as friends or foe in these conditions.

Methods and Results

In this review, we briefly review the origins of tissue resident and infiltrating macrophages and the importance of cellular crosstalking between macrophages and other resident cells in tissue regeneration. The primary objective of this review is to summarize our knowledge of the distinct roles of tissue resident and infiltrating macrophages, the impact of M1 and M2 macrophage phenotypes, and emerging evidence on macrophage crosstalking in pancreatic injury, regeneration, and disease.

Conclusion

Macrophages are involved with various stages of pancreatic cancer development, pancreatitis, and diabetes. Elucidating their role in these conditions will aid the development of targeted therapeutic treatments.

Landscape of Intercellular Crosstalk in Healthy and NASH Liver Revealed by Single-Cell Secretome Gene Analysis

Cell-cell communication via ligand-receptor signaling is a fundamental feature of complex organs. Despite this, the global landscape of intercellular signaling in mammalian liver has not been elucidated. Here we perform single-cell RNA sequencing on non-parenchymal cells isolated from healthy and NASH mouse livers. Secretome gene analysis revealed a highly connected network of intrahepatic signaling and disruption of vascular signaling in NASH. We uncovered the emergence of NASH-associated macrophages (NAMs), which are marked by high expression of triggering receptors expressed on myeloid cells 2 (Trem2), as a feature of mouse and human NASH that is linked to disease severity and highly responsive to pharmacological and dietary interventions. Finally, hepatic stellate cells (HSCs) serve as a hub of intrahepatic signaling via HSC-derived stellakines and their responsiveness to vasoactive hormones. These results provide unprecedented insights into the landscape of intercellular crosstalk and reprogramming of liver cells in health and disease.

Are Liver Pericytes Just Precursors of Myofibroblasts in Hepatic Diseases? Insights from the Crosstalk between Perivascular and Inflammatory Cells in Liver Injury and Repair

Cirrhosis, a late form of liver disease, is characterized by extensive scarring due to exacerbated secretion of extracellular matrix proteins by myofibroblasts that develop during this process. These myofibroblasts arise mainly from hepatic stellate cells (HSCs), liver-specific pericytes that become activated at the onset of liver injury. Consequently, HSCs tend to be viewed mainly as myofibroblast precursors in a fibrotic process driven by inflammation. Here, the molecular interactions between liver pericytes and inflammatory cells such as macrophages and neutrophils at the first moments after injury and during the healing process are brought into focus. Data on HSCs and pericytes from other tissues indicate that these cells are able to sense pathogen- and damage-associated molecular patterns and have an important proinflammatory role in the initial stages of liver injury. On the other hand, further data suggest that as the healing process evolves, activated HSCs play a role in skewing the initial proinflammatory (M1) macrophage polarization by contributing to the emergence of alternatively activated, pro-regenerative (M2-like) macrophages. Finally, data suggesting that some HSCs activated during liver injury could behave as hepatic progenitor or stem cells will be discussed.

Salvianolic Acid B Inhibits Activation of Human Primary Hepatic Stellate Cells Through Downregulation of the Myocyte Enhancer Factor 2 Signaling Pathway

Various isoforms of myocyte enhancer factor 2 (MEF2) have been shown to play a role in the activation of rat hepatic stellate cells (HSCs) in culture. The signals that regulate MEF2 in HSCs are unknown. In addition, whether MEF2s regulate the activation of human HSCs (H-HSCs) is unclear. Here, we studied the expression and function of MEF2s in H-HSCs. Our data showed that the levels of MEF2A, C, and D proteins were high in liver tissues from patients with cirrhosis and increased during culture-induced activation of primary H-HSCs. Exposure of H-HSCs to transforming growth factor beta 1 (TGF-β1) led to a significant increase in MEF2A and C protein levels and enhanced MEF2 activity. Interestingly, TGF-β1 did not further enhance MEF2D levels. Furthermore, TGF-β1 activated p38 mitogen-activated protein kinase (MAPK) and led to increased phosphorylation of MEF2C at its p38 recognition site. Inhibition of p38 MAPK inhibited both TGF-β1- and culture-induced activation of MEF2. The activity of collagen I reporter in H-HSCs was significantly reduced when MEF2A and MEF2C were blocked with overexpression of dominant negative MEF2 mutants. Salvianolic-acid B (SA-B), a water-soluble element of Salvia miltiorrhiza known to have anti-fibrosis effects, attenuated both basal and TGF-β1-induced increased levels of MEF2A and C mRNA and protein. In addition, SA-B inhibited MEF2 activity, which correlated with reduced expression of the HSC activation markers, α-smooth muscle actin (α-SMA), and collagen I. Administration of SA-B reduced MEF2A in vivo, which was accompanied by reduced levels of α-SMA in a model of dimethylnitrosamine-induced rat liver fibrosis. We concluded that the MEF2 transcription factor was stimulated by TGF-β1 in H-HSCs. Antagonizing TGF-β1-induced activation of the MEF2 signaling pathway may account in part for the anti-fibrosis effects of SA-B.

Haemostatic potential of human bone marrow-derived mesenchymal stromal cells in Wistar rats with carbon tetrachloride induced liver cirrhosis

Background

To evaluate the haemostatic potential of human bone marrow-derived mesenchymal stromal cells (BM-MSCs) in carbon tetrachloride (CCl₄) induced liver cirrhosis in Wistar rats.

Methods

This was an experimental study. Liver cirrhosis was induced in adult female Wistar rats using CCl₄. Rats were randomly divided into 6 groups with ten rats in each group: group 1 (normal control group), group 2 (received only CCl₄), group 3 (CCl₄ + low dose BM-MSCs), group 4 (CCl₄ + high dose BM-MSCs), group 5 (CCl₄ + silymarin), group 6 (CCl₄ + high dose BM-MSCs + silymarin). Thirty days after the treatment, blood samples were collected for liver enzyme level analysis, prothrombin time test and plasma fibrinogen estimations. The rats were then sacrificed, livers were excised and used for histopathological and scanning electron microscopy (SEM) study.

Results

BM-MSCs and the combination treatment of high dose BM-MSCs and silymarin effectively decreased the prothrombin time and increased plasma fibrinogen concentration in rats with CCl₄ induced liver cirrhosis. BM-MSCs treatment produces significant anti-fibrotic effect which was supported by the liver enzyme level analysis, histopathology and SEM study.

Conclusions

Results indicate that treatment of BM-MSCs in combination with silymarin had a better haemostatic effect when compared to the administration of BM-MSCs alone.

New Concepts on Reversibility and Targeting of Liver Fibrosis; A Review Article

Currently, liver fibrosis and its complications are regarded as critical health problems. With the studies showing the reversible nature of liver fibrogenesis, scientists have focused on understanding the underlying mechanism of this condition in order to develop new therapeutic strategies. Although hepatic stellate cells are known as the primary cells responsible for liver fibrogenesis, studies have shown contributing roles for other cells, pathways, and molecules in the development of fibrosis depending on the etiology of liver fibrosis. Hence, interventions could be directed in the proper way for each type of liver diseases to better address this complication. There are two main approaches in clinical reversion of liver fibrosis; eliminating the underlying insult and targeting the fibrosis process, which have variable clinical importance in the treatment of this disease. In this review, we present recent concepts in molecular pathways of liver fibrosis reversibility and their clinical implications.

Nerve growth factor upregulates sirtuin 1 expression in cholestasis: a potential therapeutic target

This study investigated the regulatory role of nerve growth factor (NGF) in sirtuin 1 (SIRT1) expression in cholestatic livers. We evaluated the expression of NGF and its cognate receptors in human livers with hepatolithiasis and the effects of NGF therapy on liver injury and hepatic SIRT1 expression in a bile duct ligation (BDL) mouse model. Histopathological and molecular analyses showed that the hepatocytes of human diseased livers expressed NGF, proNGF (a precursor of NGF), TrkA and p75NTR, whereas only p75NTR was upregulated in hepatolithiasis, compared with non-hepatolithiasis livers. In the BDL model without NGF therapy, p75NTR, but not TrkA antagonism, significantly deteriorated BDL-induced liver injury. By contrast, the hepatoprotective effect of NGF was abrogated only by TrkA and not by p75NTR antagonism in animals receiving NGF therapy. Intriguingly, a positive correlation between hepatic SIRT1 and NGF expression was found in human livers. In vitro studies demonstrated that NGF upregulated SIRT1 expression in mouse livers and human Huh-7 and rodent hepatocytes. Both NGF and proNGF induced protective effects against hydrogen peroxide-induced cytotoxicity in Huh-7 cells, whereas inhibition of TrkA and p75NTR activity prevented oxidative cell death. Mechanistically, NGF, but not proNGF, upregulated SIRT1 expression in human Huh-7 and rodent hepatocytes via nuclear factor (NF)-κB activity, whereas NGF-induced phosphoinositide-3 kinase/Akt, extracellular signal–regulated kinase and NF-κB signaling and SIRT1 activity were involved in its hepatoprotective effects against oxidative injury. These findings suggest that pharmacological manipulation of the NGF/SIRT1 axis might serve as a novel approach for the treatment of cholestatic disease.

Human hepatic stellate cell isolation and characterization

The hepatic stellate cells (HSCs) localize at the space of Disse in the liver and have multiple functions. They are identified as the major contributor to hepatic fibrosis. Significant understanding of HSCs has been achieved using rodent models and isolated murine HSCs; as well as investigating human liver tissues and human HSCs. There is growing interest and need of translating rodent study findings to human HSCs and human liver diseases. However, species-related differences impose challenges on the translational research. In this review, we focus on the current information on human HSCs isolation methods, human HSCs markers, and established human HSC cell lines.

Serum and tissue markers in hepatocellular carcinoma and cholangiocarcinoma: clinical and prognostic implications

HCC represents the sixth most common cancer worldwide and the second leading cause of cancer-related death. Despite the high incidence, treatment options for advanced HCC remain limited and unsuccessful, resulting in a poor prognosis. Despite the major advances achieved in the diagnostic management of HCC, only one third of the newly diagnosed patients are presently eligible for curative treatments. Advances in technology and an increased understanding of HCC biology have led to the discovery of novel biomarkers. Improving our knowledge about serum and tissutal markers could ultimately lead to an early diagnosis and better and early treatment strategies for this deadly disease. Serum biomarkers are striking potential tools for surveillance and early diagnosis of HCC thanks to the non-invasive, objective, and reproducible assessments they potentially enable. To date, many biomarkers have been proposed in the diagnosis of HCC. Cholangiocarcinoma (CCA) is an aggressive malignancy, characterized by early lymph node involvement and distant metastasis, with 5-year survival rates of 5%-10%. The identification of new biomarkers with diagnostic, prognostic or predictive value is especially important as resection (by surgery or combined with a liver transplant) has shown promising results and novel therapies are emerging. However, the relatively low incidence of CCA, high frequency of co-existing cholestasis or cholangitis (primary sclerosing cholangitis –PSC- above all), and difficulties with obtaining adequate samples, despite advances in sampling techniques and in endoscopic visualization of the bile ducts, have complicated the search for accurate biomarkers. In this review, we attempt to analyze the existing literature on this argument.

Nanoparticles for the treatment of liver fibrosis

Chronic liver diseases represent a global health problem due to their high prevalence worldwide and the limited available curative treatment options. They can result from various causes, both infectious and noninfectious diseases. The application of nanoparticle (NP) systems has emerged as a rapidly evolving area of interest for the safe delivery of various drugs and nucleic acids for chronic liver diseases. This review presents the pathogenesis, diagnosis and the emerging nanoparticulate systems used in the treatment of chronic liver diseases caused by liver fibrosis. Activated hepatic stellate cell (HSC) is considered to be the main mechanism for liver fibrosis. Ultrasonography and magnetic resonance imaging techniques are widely used noninvasive diagnostic methods for hepatic fibrosis. A variety of nanoparticulate systems are mainly focused on targeting HSC in the treatment of hepatic fibrosis. As early liver fibrosis is reversible by current NP therapy, it is being studied in preclinical as well as clinical trials. Among various nanoparticulate systems, inorganic NPs, liposomes and nanomicelles have been widely studied due to their distinct properties to deliver drugs as well as other therapeutic moieties. Liposomal NPs in clinical trials is considered to be a milestone in the treatment of hepatic fibrosis. Currently, NP therapy for liver fibrosis is updating fast, and hopefully, it can be the future remedy for liver fibrosis.

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

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

Nerve Growth Factor: A Focus on Neuroscience and Therapy

Nerve growth factor (NGF) is the firstly discovered and best characterized neurotrophic factor, known to play a critical protective role in the development and survival of sympathetic, sensory and forebrain cholinergic neurons. NGF promotes neuritis outgrowth both in vivo and in vitro and nerve cell recovery after ischemic, surgical or chemical injuries. Recently, the therapeutic property of NGF has been demonstrated on human cutaneous and corneal ulcers, pressure ulcer, glaucoma, maculopathy and retinitis pigmentosa. NGF eye drops administration is well tolerated, with no detectable clinical evidence of systemic or local adverse effects. The aim of this review is to summarize these biological properties and the potential clinical development of NGF.

Pharmacological Intervention in Hepatic Stellate Cell Activation and Hepatic Fibrosis

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

NGF Modulates trkANGFR/p75NTR in αSMA-Expressing Conjunctival Fibroblasts from Human Ocular Cicatricial Pemphigoid (OCP)

Objective

In a previous study, we reported the upregulation of Nerve Growth Factor (NGF) and trkA^NGFR expression in Ocular Cicatricial Pemphigoid (OCP), an inflammatory and remodeling eye disease. Herein, we hypothesize a potential NGF-driven mechanism on fibroblasts (FBs) during OCP remodeling events. To verify, human derived OCP-FBs were isolated and characterized either at baseline or after NGF exposure.

Materials and Methods

Conjunctival biopsies were obtained from 7 patients having OCP and 6 control subjects (cataract surgery). Both conjunctivas and primary FB cultures were characterised for αSMA, NGF and trkA^NGFR/p75^NTR expression. Subcultures were exposed to NGF and evaluated for αSMA, NGF, trkA^NGFR/p75^NTR expression as well as TGFβ1/IL4 release. For analysis, early and advanced subgroups were defined according to clinical parameters.

Results

OCP-conjunctivas showed αSMA-expressing FBs and high NGF levels. Advanced OCP-FBs showed higher αSMA expression associated with higher p75^NTR and lower trkA^NGFR expression, as compared to early counterparts. αSMA expression was in keeping with disease severity and correlated to p75^NTR. NGF exposure did not affect trkA^NGFR levels in early OCP-FBs while decreased both αSMA/p75^NTR expression and TGFβ1/IL4 release. These effects were not observed in advanced OCP-FBs.

Conclusions

Taken together, these data are suggestive for a NGF/p75^NTR task in the potential modulation of OCP fibrosis and encourages further studies to fully understand the underlying mechanism occurring in fibrosis. NGF/p75^NTR might be viewed as a potential therapeutic target.

Repeated versus single transplantation of mesenchymal stem cells in carbon tetrachloride-induced liver injury in mice

Despite its numerous limitations, liver transplants are the only definite cure for end-stage liver disease. Various stem cell populations may contribute to liver regeneration, of which there is accumulating evidence of the contribution of mesenchymal stem cells (MSCs). This study examines the hypothesis that repeated infusions of human bone marrow-derived MSCs (hBMMSCs)can improve liver injury in an experimental model. MSCs were intravenously transplanted into immunosuppressed mice with carbon tetrachloride (CCl(4))-induced liver fibrosis. Transplanting 3x10(6) MSCs in three divided doses improved survival,liver fibrosis and necrosis compared with injection of the same number of MSCs in a single dose. This was accompanied by increased influence on the expression of the fibrogenic/fibrolytic related genes Col1a1, Timp1 and Mmp13 in the repeated transplant group. Repeat administration of MSCs was three times more effective in homing of PKH-tagged transplanted cells 3 weeks post-transplant compared with the single transplant group. The benefits of repeated transplants may be of considerable significance in clinical trials on liver failure.

Basic fibroblast growth factor-treated adipose tissue-derived mesenchymal stem cell infusion to ameliorate liver cirrhosis via paracrine hepatocyte growth factor

BACKGROUND AND AIM

Recent studies show that adipose tissue-derived mesenchymal stem cells have potential clinical applications. However, the mechanism has not been fully elucidated yet. Here, we investigated the effect of basic fibroblast growth factor-treated adipose tissue-derived mesenchymal stem cells infusion on a liver fibrosis rat model and elucidated the underlying mechanism.

METHODS

Adipose tissue-derived mesenchymal stem cells were infused into carbon tetrachloride-induced hepatic fibrosis rats through caudal vein. Liver functions and pathological changes were assessed. A co-culture model was used to clarify the potential mechanism.

RESULTS

Basic fibroblast growth factor treatment markedly improved the proliferation, differentiation, and hepatocyte growth factor expression ability of adipose tissue-derived mesenchymal stem cells. Although adipose tissue-derived mesenchymal stem cells infusion alone slightly ameliorated liver functions and suppressed fibrosis progression, basic fibroblast growth factor-treatment significantly enhanced the therapeutic effect in association with elevated hepatocyte growth factor expression. Moreover, double immunofluorescence staining confirmed that the infused cells located in fibrosis area. Furthermore, co-culture with adipose tissue-derived mesenchymal stem cell led to induction of hepatic stellate cell apoptosis and enhanced hepatocyte proliferation. However, these effects were significantly weakened by knockdown of hepatocyte growth factor. Mechanism investigation revealed that co-culture with adipose tissue-derived mesenchymal stem cells activated c-jun N-terminal kinase-p53 signaling in hepatic stellate cell and promoted apoptosis.

CONCLUSIONS

Basic fibroblast growth factor treatment enhanced the therapeutic effect of adipose tissue-derived mesenchymal stem cells, and secretion of hepatocyte growth factor from adipose tissue-derived mesenchymal stem cells plays a critical role in amelioration of liver injury and regression of fibrosis.

Association of interleukin-6 polymorphisms with susceptibility to hepatocellular carcinoma

TARGET

Our study was to investigate the effects of interleukin-6 (IL-6) polymorphisms (rs2069837 and rs17147230) on the risk for hepatocellular carcinoma (HCC).

METHODS

A total of 226 HCC cases and 220 healthy controls were admitted into the study and genomic DNA was extracted from the peripheral blood. The genotyping was conducted by the method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Odds ratio (OR) and 95% confidence interval (CI) were used to evaluate the relationship of IL-6 rs2069837 and rs17147230 polymorphisms with HCC susceptibility.

RESULTS

The frequency of GG genotype of rs2069837 was higher in HCC patients, compared with controls (P < 0.05). Moreover, the results indicated that GG genotype was related with increased risk for HCC (OR = 2.303, 95% CI = 1.056-5.025). Similarly, the risk for G allele carriers was higher than that of A allele (OR = 1.392, 95% CI = 1.046-1.852). For rs17147230, TT genotype showed strong effect on HCC susceptibility (OR = 2.089, 95% CI = 1.135-3.845) and T allele appeared to be a risk factor for HCC (OR = 1.326, 95% CI = 1.010-1.740). Further analysis showed that G-T haplotype was associated with increased risk for HCC (OR = 3.125, 95% CI = 1.845-5.294, P = 0.000).

CONCLUSION

IL-6 rs2069837 as well as rs17147230 were associated with HCC susceptibility. In addition, G-T haplotype also served as a genetic-susceptibility factor for HCC.

NGF and P75NTR gene expression is associated with the hepatic fibrosis stage due to viral and non-viral causes

This study evaluated the relative mRNA expression levels of nerve growth factor (NGF) and the p75 neurothrophin receptor (p75^NTR) in different histological stages of human liver disease. Fifty-one liver biopsy specimens obtained from patients with hepatitis B virus (n = 6), hepatitis C virus (n = 28), and non-viral hepatitis – (n = 9) and standard histological liver (n = 8) as controls (CT) were subjected to qPCR and histopathological exams. Our data revealed a significant difference in the NGF expression levels between the three patient groups and the Control group. p75^NTR expression levels in the HCV and NVH groups were higher than those observed in the HBV and Control groups. In cases of liver cirrhosis, higher p75^NTR mRNA expression was observed, whereas NGF was expressed at higher levels in patients with hepatic fibrosis. NGF expression was lower in the F1 liver fibrosis stage, and p75^NTR receptor expression continuously and proportionately increased compared to the increase in the degree of fibrosis and was significantly higher in livers in fibrosis stages 3 and 4. The hepatic levels of NGF and p75^NTR were decreased and increased, respectively, relative to the stage of inflammatory activity. A positive correlation between p75^NTR and NGF gene expression was observed in livers with mild to moderate fibrosis, though not in cases of severe fibrosis and cirrhosis.

Up-regulation of nerve growth factor in cholestatic livers and its hepatoprotective role against oxidative stress

The role of nerve growth factor (NGF) in liver injury induced by bile duct ligation (BDL) remains elusive. This study aimed to investigate the relationship between inflammation and hepatic NGF expression, to explore the possible upstream molecules up-regulating NGF, and to determine whether NGF could protect hepatocytes from oxidative liver injury. Biochemical and molecular detection showed that NGF was up-regulated in cholestatic livers and plasma, and well correlated with systemic and hepatic inflammation. Conversely, systemic immunosuppression reduced serum NGF levels and resulted in higher mortality in BDL-treated mice. Immunohistochemistry showed that the up-regulated NGF was mainly localized in parenchymal hepatocytes. In vitro mechanistic study further demonstrated that TGF-β1 up-regulated NGF expression in clone-9 and primary rat hepatocytes. Exogenous NGF supplementation and endogenous NGF overexpression effectively protected hepatocytes against TGF-β1- and oxidative stress-induced cell death in vitro, along with reduced formation of oxidative adducted proteins modified by 4-HNE and 8-OHdG. TUNEL staining confirmed the involvement of anti-apoptosis in the NGF-exhibited hepatoprotection. Moreover, NGF potently induced Akt phosphorylation and increased Bcl-2 to Bax ratios, whereas these molecular alterations by NGF were only seen in the H₂O₂-, but not TGF-β1-treated hepatocytes. In conclusion, NGF exhibits anti-oxidative and hepatoprotective effects and is suggested to be therapeutically applicable in treating cholestatic liver diseases.

The therapeutic effects of bone marrow-derived mesenchymal stem cells and simvastatin in a rat model of liver fibrosis

Liver fibrosis is the excessive accumulation of extracellular matrix (ECM) proteins including collagen that occurs in most types of chronic liver diseases. Studies concerning the capacity of mesenchymal stem cells (MSCs) and simvasatain (SIMV) to repair fibrotic tissues through reducing inflammation, collagen deposition, are still controversial. This study aimed to investigate the therapeutic efficacy of bone marrow (BM)-derived MSCs and SIMV on carbon tetrachloride (CCl4)-induced liver fibrosis in rats. Rats were divided into: normal, CCl4, CCl4/MSCs, CCl4/SIMV, CCl4/MSCs/SIMV, and SIMV groups. BM-derived MSCs were detected by RT-PCR of CD29 and were then infused into the tail vein of female rats that received CCl4 injection to induce liver fibrosis. Sex-determining region Y (SRY) gene on Y-chromosome gene was assessed by PCR to confirm homing of the male stem cells in liver tissue of the female recipients. Serum liver function tests, liver procollagens I and III, tissue inhibitors of metalloproteinase-1 (TIMP-1), endoglin, matrix metalloproteinase-1 (MMP-1) gene expressions, transforming growth factor-beta (TGF-β1) immunostaining, and histopathologicl examination were performed. MSCs and SIMV decreased liver procollagens I and III, TIMP-1 and endoglin gene expressions, TGF-β1 immunostaining, and serum liver function tests compared with the CCl4 group. MMP-1 expression was increased in the CCl4/MSCs group. Histopathological examination as well as fibrosis score supports the biochemical and molecular findings. It can be concluded that MSCs and SIMV were effective in the treatment of hepatic CCl4-induced fibrosis-rat model. Treatment with MSCs was superior to SIMV. This antifibrotic effect can be attributed to their effect on the MMPs/TIMPs balance which is central in fibrogenesis.

Sciatic nerve regeneration using a nerve growth factor-containing fibrin glue membrane

Our previous findings confirmed that the nerve growth factor-containing fibrin glue membrane provides a good microenvironment for peripheral nerve regeneration; however, the precise mechanism remains unclear. p75 neurotrophin receptor (p75(NTR)) plays an important role in the regulation of peripheral nerve regeneration. We hypothesized that a nerve growth factor-containing fibrin glue membrane can promote neural regeneration by up-regulating p75(NTR) expression. In this study, we used a silicon nerve conduit to bridge a 15 mm-long sciatic nerve defect and injected a mixture of nerve growth factor and fibrin glue at the anastomotic site of the nerve conduit and the sciatic nerve. Through RT-PCR and western blot analysis, nerve growth factor-containing fibrin glue membrane significantly increased p75(NTR) mRNA and protein expression in the Schwann cells at the anastomotic site, in particular at 8 weeks after injection of the nerve growth factor/fibrin glue mixture. These results indicate that nerve growth factor-containing fibrin glue membrane can promote peripheral nerve regeneration by up-regulating p75(NTR) expression in Schwann cells.

Intractable diseases treated with intra-bone marrow-bone marrow transplantation

Bone marrow transplantation (BMT) is used to treat hematological disorders, autoimmune diseases (ADs) and lymphoid cancers. Intra bone marrow-BMT (IBM-BMT) has been proven to be a powerful strategy for allogeneic BMT due to the rapid hematopoietic recovery and the complete restoration of T cell functions. IBM-BMT not only replaces hematopoietic stem cells (HSCs) but also mesenchymal stromal cells (MSCs). MSCs are multi-potent stem cells that can be isolated from bone marrow (BM), umbilical cord blood (UCB), and adipose tissue. MSCs play an important role in the support of hematopoiesis, and modify and influence the innate and adaptive immune systems. MSCs also differentiate into mesodermal, endodermal and ectodermal lineage cells to repair tissues. This review aims to summarize the functions of BM-derived-MSCs, and the treatment of intractable diseases such as rheumatoid arthritis (RA) and malignant tumors with IBM-BMT.

Pancreatic Cancer: Clinical Significance of Biomarkers

BACKGROUND

Improvement in the prognosis of patients with pancreatic cancer, novel effective screening and diagnostic strategies and treatments are needed. Recent advances in the understanding of pancreatic carcinogenesis and tumor microenvironment have allowed identification of biomarkers for screening, diagnosis and prediction of cancer treatments, including novel therapies targeting specific cancer or stromal cell subpopulations. Personalized therapy in pancreatic cancer is also promising as several drugs such as S1, capecitabine and gemcitabine reportedly have significant therapeutic effects. Predictive markers are thus needed to select patients most likely to benefit from therapies based on gemcitabine or other drugs.

SUMMARY

We review the clinical significance of promising screening, diagnostic, predictive and prognostic biomarkers based on genetic and epigenetic alterations and microRNA abnormalities in pancreatic cancer. We also review new types of biomarkers based on stromal cells, such as pancreatic stellate cells, in the microenvironment of pancreatic cancer.

β-Nerve growth factor attenuates hepatocyte injury induced by D-galactosamine in vitro via TrkA NGFR

Nerve growth factor (NGF) regulates the proliferation, differentiation and survival of cells and is also involved in the wound healing and tissue remodeling processes. The biological effects of NGF are dependent upon receptor signal-mediating functions, which differ between cells. This study attempted to investigate the hepatoprotective effect and possible mechanism of β-NGF on D-galactosamine (D-GalN)-injured human liver L-02 cell lines. We demonstrated that L-02 cells expressed the neurotrophin receptors tyrosine kinase-A nerve growth factor receptor (TrkA NGFR) and p75 pan-neurotrophin receptor (p75NTR). Recombinant human β-NGF markedly reduced cell injury and promoted the proliferation of L-02 cells damaged by D-GalN. However, this proliferation effect was blocked by the anti-TrkA NGFR antibody. Lactate dehydrogenase (LDH) and malondialdehyde (MDA) were released at reduced levels in the L-02 cell culture supernatant pretreated with β-NGF. Furthermore, the albumin (ALB) content in the cell medium and intracellular glutathione (GSH) levels were markedly augmented, and the permeability of the mitochondrial membrane of the L-02 cells was improved by β-NGF. Our results suggested that exogenous β-NGF protects L-02 cells from D-GalN-induced injury through the NGF/TrkA NGFR signaling pathway.

p75 neurotrophin receptor is a clock gene that regulates oscillatory components of circadian and metabolic networks

The p75 neurotrophin receptor (p75(NTR)) is a member of the tumor necrosis factor receptor superfamily with a widespread pattern of expression in tissues such as the brain, liver, lung, and muscle. The mechanisms that regulate p75(NTR) transcription in the nervous system and its expression in other tissues remain largely unknown. Here we show that p75(NTR) is an oscillating gene regulated by the helix-loop-helix transcription factors CLOCK and BMAL1. The p75(NTR) promoter contains evolutionarily conserved noncanonical E-box enhancers. Deletion mutagenesis of the p75(NTR)-luciferase reporter identified the -1039 conserved E-box necessary for the regulation of p75(NTR) by CLOCK and BMAL1. Accordingly, gel-shift assays confirmed the binding of CLOCK and BMAL1 to the p75(NTR-)1039 E-box. Studies in mice revealed that p75(NTR) transcription oscillates during dark and light cycles not only in the suprachiasmatic nucleus (SCN), but also in peripheral tissues including the liver. Oscillation of p75(NTR) is disrupted in Clock-deficient and mutant mice, is E-box dependent, and is in phase with clock genes, such as Per1 and Per2. Intriguingly, p75(NTR) is required for circadian clock oscillation, since loss of p75(NTR) alters the circadian oscillation of clock genes in the SCN, liver, and fibroblasts. Consistent with this, Per2::Luc/p75(NTR-/-) liver explants showed reduced circadian oscillation amplitude compared with those of Per2::Luc/p75(NTR+/+). Moreover, deletion of p75(NTR) also alters the circadian oscillation of glucose and lipid homeostasis genes. Overall, our findings reveal that the transcriptional activation of p75(NTR) is under circadian regulation in the nervous system and peripheral tissues, and plays an important role in the maintenance of clock and metabolic gene oscillation.

Development of Adenoviral Delivery Systems to Target Hepatic Stellate Cells In Vivo

Hepatic stellate cells (HSCs) are known as initiator cells that induce liver fibrosis upon intoxication or other noxes. Deactivation of this ongoing remodeling process of liver parenchyma into fibrotic tissue induced by HSCs is an interesting goal to be achieved by targeted genetic modification of HSCs. The most widely applied approach in gene therapy is the utilization of specifically targeted vectors based on Adenovirus (Ad) serotype 5. To narrow down the otherwise ubiquitous tropism of parental Ad, two modifications are required: a) ablating the native tropism and b) redirecting the vector particles towards a specific entity solely present on the cells of interest. Therefore, we designed a peptide of the nerve growth factor (NGF_p) with specific affinity for the p75 neurotrophin receptor (p75NTR) present on HSCs. Coupling of this NGF_p to vector particles was done either via chemical conjugation using bifunctional polyethylene glycol (PEG) or, alternatively, by molecular bridging with a fusion protein specific for viral fiber knob and p75NTR. Both Ad vectors transmit the gene for the green fluorescent protein (GFP). GFP expression was monitored in vitro on primary murine HSCs as well as after systemic administration in mice with healthy and fibrotic livers using intravital fluorescence microscopy. Coupling of NGF_p to Ad via S11 and/or PEGylation resulted in markedly reduced liver tropism and an enhanced adenoviral-mediated gene transfer to HSCs. Transduction efficiency of both specific Ads was uniformly higher in fibrotic livers, whereas Ad.GFP-S11-NGF_p transduce activated HSCs better than Ad.GFP-PEG-NGF_p. These experiments contribute to the development of a targeted gene transfer system to specifically deliver antifibrotic compounds into activated HSCs by systemically applied adenoviral vector modified with NGF_p.

Next generation sequencing of the Ago2 interacting transcriptome identified chemokine family members as novel targets of neuronal microRNAs in hepatic stellate cells

BACKGROUND & AIMS

After myofibroblastic transdifferentiation, hepatic stellate cells (HSC), mainly involved in liver fibrosis by extracellular matrix production, exhibit an altered growth factor profile including increased expression of neuronal mediators. Here, we analyzed putative targets of neuronal microRNAs miR-9, miR-125b, and miR-128 by deep sequencing of the transcript population, interacting with the miRNA/Argonaute 2 (Ago2) complex in myofibroblastic HSC.

METHODS

MicroRNA expression was quantified by real-time PCR in primary HSC, isolated from the rat or human liver. Myofibroblastic HSC were transfected either with mimics or inhibitors of miR-9, miR-125b, and miR-128. RNA from immunoprecipitated Ago2-miRNA/transcript complexes was purified and used for next generation sequencing. Additionally, gene expression was investigated in quiescent and activated primary HSC, treated with the miR-128 mimic or inhibitor, by microarray analysis.

RESULTS

During myofibroblastic transdifferentiation of HSC, miR-9, miR-125b, and miR-128 expression was markedly increased. Transcriptome analysis of Ago2 bound mRNA by deep sequencing identified a broad spectrum of transcripts that interact with neuronal miRNAs in myofibroblastic HSC. In particular, in HSC overexpressing miR-128, many members of the chemokine family were bound to the Ago2 repression complex. Furthermore, a comprehensive profiling of gene expression demonstrates the high impact of neuronal miRNAs on the chemokine network.

CONCLUSIONS

Ago2 immunoprecipitation followed by deep sequencing is a useful tool to identify novel miRNA targets. Upregulation of neuronal miR-9, miR-125b, and miR-128 during myofibroblastic transition and the identified interaction with a wide range of chemokines and chemokine receptors suggest a prominent role of neuronal miRNAs in the inflammatory response of HSC during fibrosis.

CD271⁺ subpopulation of pancreatic stellate cells correlates with prognosis of pancreatic cancer and is regulated by interaction with cancer cells

Pancreatic stellate cells (PSCs) play a crucial role in the aggressive behavior of pancreatic cancer. Although heterogeneity of PSCs has been identified, the functional differences remain unclear. We characterized CD271⁺ PSCs in human pancreatic cancer. Immunohistochemistry for CD271 was performed for 31 normal pancreatic tissues and 105 pancreatic ductal adenocarcinomas (PDACs). We performed flow cytometry and quantitative RT-PCR, and assessed CD271 expression in PSCs isolated from pancreatic tissues and the changes in CD271 expression in PSCs cocultured with cancer cells. We also investigated the pattern of CD271 expression in a SCID mouse xenograft model. In the immunohistochemical analyses, the CD271-high staining rates in pancreatic stroma in normal pancreatic tissues and PDACs were 2/31 (6.5%) and 29/105 (27.6%), respectively (p = 0.0069). In PDACs, CD271⁺ stromal cells were frequently observed on the edge rather than the center of the tumors. Stromal CD271 high expression was associated with a good prognosis (p = 0.0040). Flow cytometric analyses demonstrated CD271-positive rates in PSCs were 0–2.1%. Quantitative RT-PCR analyses revealed that CD271 mRNA expression was increased in PSCs after coculture with pancreatic cancer cells. However, the level of CD271 mRNA expression subsequently decreased after the transient increase. Furthermore, CD271 mRNA expression was decreased in PSCs migrating toward pancreatic cancer cells through Matrigel. In the xenograft model, CD271⁺ PSCs were present at tumor margins/periphery and were absent in the tumor core. In conclusion, CD271 was expressed in PSCs around pancreatic tumors, but not in the center of the tumors, and expression decreased after long coculture with pancreatic cancer cells or after movement toward pancreatic cancer cells. These findings suggest that CD271⁺ PSCs appear at the early stage of pancreatic carcinogenesis and that CD271 expression is significantly correlated with a better prognosis in patients with PDAC.

Chronic nerve growth factor exposure increases apoptosis in a model of in vitro induced conjunctival myofibroblasts

In the conjunctiva, repeated or prolonged exposure to injury leads to tissue remodeling and fibrosis associated with dryness, lost of corneal transparency and defect of ocular function. At the site of injury, fibroblasts (FB) migrate and differentiate into myofibroblasts (myoFB), contributing to the healing process together with other cell types, cytokines and growth factors. While the physiological deletion of MyoFB is necessary to successfully end the healing process, myoFB prolonged survival characterizes the pathological process of fibrosis. The reason for myoFB persistence is poorly understood. Nerve Growth Factor (NGF), often increased in inflamed stromal conjunctiva, may represent an important molecule both in many inflammatory processes characterized by tissue remodeling and in promoting wound-healing and well-balanced repair in humans. NGF effects are mediated by the specific expression of the NGF neurotrophic tyrosine kinase receptor type 1 (trkA(NGFR)) and/or the pan-neurotrophin glycoprotein receptor (p75(NTR)). Therefore, a conjunctival myoFB model (TGFβ1-induced myoFB) was developed and characterized for cell viability/proliferation as well as αSMA, p75(NTR) and trkA(NGFR) expression. MyoFB were exposed to acute and chronic NGF treatment and examined for their p75(NTR)/trkA(NGFR), αSMA/TGFβ1 expression, and apoptosis. Both NGF treatments significantly increased the expression of p75(NTR), associated with a deregulation of both αSMA/TGFβ1 genes. Acute and chronic NGF exposures induced apoptosis in p75(NTR) expressing myoFB, an effect counteracted by the specific trkA(NGFR) and/or p75(NTR) inhibitors. Focused single p75(NTR) and double trkA(NGFR)/p75(NTR) knocking-down experiments highlighted the role of p75(NTR) in NGF-induced apoptosis. Our current data indicate that NGF is able to trigger in vitro myoFB apoptosis, mainly via p75(NTR). The trkA(NGFR)/p75(NTR) ratio in favor of p75(NTR) characterizes this process. Due to the lack of effective pharmacological agents for balanced tissue repairs, these new findings suggest that NGF might be a suitable therapeutic tool in conditions with impaired tissue healing.

Enhanced expression of neuronal proteins in idiopathic frozen shoulder

BACKGROUND

Our understanding of the pathogenesis of frozen shoulder and why it is so painful is undetermined. This study investigated the expression of neuronal proteins in the capsular tissue of frozen shoulder.

METHODS

Shoulder capsular samples were collected from 8 patients with idiopathic adhesive capsulitis and 10 patients with a rotator cuff tear but no stiffness (controls). Samples were analyzed by immunohistochemistry using antibodies against protein gene product 9.5 (PGP9.5), a general nerve marker; growth associated protein 43 (GAP43), a nerve growth marker; nerve growth factor receptor p75; and CD34, an endothelial cell marker.

RESULTS

Samples from frozen shoulders showed subsynovial hypercellularity and fibroblastic proliferation, with increased expression of nerve growth factor receptor p75 and CD34 compared with controls. Nerves positive for PGP9.5 and GAP43 were more abundant in samples of frozen shoulder (2.8 ± 0.2 and 2.4 ± 0.4 per field; P < .01) compared with controls (1.6 ± 0.3 and 1.3 ± 0.3 per field; P < .05). Expression of neuronal proteins followed that of CD34.

CONCLUSION

Increased expression of nerve growth factor receptor and new nerve fibers were found in the shoulder capsular tissue of patients with frozen shoulder compared with those without a frozen shoulder. These data suggest that neoinnervation and neoangiogenesis in the shoulder capsule are important events in the pathogenesis of frozen shoulder and may help explain the often-severe pain of patients with frozen shoulder.

Update on hepatic stellate cells: pathogenic role in liver fibrosis and novel isolation techniques

Hepatic stellate cells (HSCs), also called Ito cells or lipocytes, are vitamin A-storing cells located in the Dissé space between hepatocytes and sinusoidal endothelial cells. Upon liver injury, these cells transdifferentiate into extracellular matrix-producing, highly proliferative myofibroblasts that promote hepatic fibrogenesis. Other possible collagen-producing cells in liver fibrosis include portal fibroblasts, bone marrow-derived cells (mesenchymal stem cells, fibrocytes and hematopoietic cells) and parenchymal cells undergoing epithelial-to-mesenchymal transition. Important factors and signaling pathways for HSC activation, as well as different functions of HSC during homeostasis and fibrosis, such as collagen production, secretion of cytokines and chemokines, immune modulation and changes in contractile features, as well as vitamin A storage capacity, have been identified in vitro and in vivo. Novel isolation techniques, specifically HSC sorting by FACS via autofluorescence and antibodies, will provide us with further opportunities to advance our understanding of HSC biology in health and disease.

Bone marrow cells ameliorate liver fibrosis and express albumin after transplantation in CCl₄-induced fibrotic liver

BACKGROUND/AIM

We investigated the effect of bone marrow-derived stem cell (BMSC) transplantation on carbon tetrachloride (CCl 4 )-induced liver fibrosis.

PATIENTS AND METHODS

BMSCs of green fluorescent protein (GFP) mice were transplanted into 4-week CCl 4 -treated C57BL/6 mice directly to the liver, and the mice were treated for 4 more weeks with CCl 4 (total, 8 weeks). After sacrificing the animals, quantitative data of percentage fibrosis area and the number of cells expressing albumin was obtained. One-way analysis of variance was applied to calculate the significance of the data.

RESULTS

GFP expressing cells clearly indicated migrated BMSCs with strong expression of albumin after 28 days post-transplantation shown by anti-albumin antibody. Double fluorescent immunohistochemistry showed reduced expression of αSMA on GFP-positive cells. Four weeks after BMSC transplantation, mice had significantly reduced liver fibrosis as compared with that of mice treated with CCl 4 assessed by Sirius red staining.

CONCLUSION

Mice with BMSC transplantation with continuous CCl 4 injection had reduced liver fibrosis and a significantly improved expression of albumin compared with mice treated with CCl 4 alone. These findings strengthen the concept of cellular therapy in liver fibrosis.

Oxygen-dependent cleavage of the p75 neurotrophin receptor triggers stabilization of HIF-1α

Homeostatic control of oxygen availability allows cells to survive oxygen deprivation. Although the transcription factor hypoxia-inducible factor 1α (HIF-1α) is the main regulator of the hypoxic response, the upstream mechanisms required for its stabilization remain elusive. Here, we show that p75 neurotrophin receptor (p75(NTR)) undergoes hypoxia-induced γ-secretase-dependent cleavage to provide a positive feed-forward mechanism required for oxygen-dependent HIF-1α stabilization. The intracellular domain of p75(NTR) directly interacts with the evolutionarily conserved zinc finger domains of the E3 RING ubiquitin ligase Siah2 (seven in absentia homolog 2), which regulates HIF-1α degradation. p75(NTR) stabilizes Siah2 by decreasing its auto-ubiquitination. Genetic loss of p75(NTR) dramatically decreases Siah2 abundance, HIF-1α stabilization, and induction of HIF-1α target genes in hypoxia. p75(NTR-/-) mice show reduced HIF-1α stabilization, vascular endothelial growth factor (VEGF) expression, and neoangiogenesis after retinal hypoxia. Thus, hypoxia-induced intramembrane proteolysis of p75(NTR) constitutes an apical oxygen-dependent mechanism to control the magnitude of the hypoxic response.