Transforming growth factor beta1 induces the expression of alpha1(I) procollagen mRNA by a hydrogen peroxide-C/EBPbeta-dependent mechanism in rat hepatic stellate cells

Metabolic reprogramming in liver fibrosis

Chronic liver diseases, primarily metabolic dysfunction-associated steatotic liver disease (MASLD), harmful use of alcohol, or viral hepatitis, may result in liver fibrosis, cirrhosis, and cancer. Hepatic fibrogenesis is a complex process with interactions between different resident and non-resident heterogeneous liver cell populations, ultimately leading to deposition of extracellular matrix and organ failure. Shifts in cell phenotypes and functions involve pronounced transcriptional and protein synthesis changes that require metabolic adaptations in cellular substrate metabolism, including glucose and lipid metabolism, resembling changes associated with the Warburg effect in cancer cells. Cell activation and metabolic changes are regulated by metabolic stress responses, including the unfolded protein response, endoplasmic reticulum stress, autophagy, ferroptosis, and nuclear receptor signaling. These metabolic adaptations are crucial for inflammatory and fibrogenic activation of macrophages, lymphoid cells, and hepatic stellate cells. Modulation of these pathways, therefore, offers opportunities for novel therapeutic approaches to halt or even reverse liver fibrosis progression.

Anti-oxidant potential of plants and probiotic spp. in alleviating oxidative stress induced by H2O2

Cells produce reactive oxygen species (ROS) as a metabolic by-product. ROS molecules trigger oxidative stress as a feedback response that significantly initiates biological processes such as autophagy, apoptosis, and necrosis. Furthermore, extensive research has revealed that hydrogen peroxide (H2O2) is an important ROS entity and plays a crucial role in several physiological processes, including cell differentiation, cell signalling, and apoptosis. However, excessive production of H2O2 has been shown to disrupt biomolecules and cell organelles, leading to an inflammatory response and contributing to the development of health complications such as collagen deposition, aging, liver fibrosis, sepsis, ulcerative colitis, etc. Extracts of different plant species, phytochemicals, and Lactobacillus sp (probiotic) have been reported for their anti-oxidant potential. In this view, the researchers have gained significant interest in exploring the potential plants spp., their phytochemicals, and the potential of Lactobacillus sp. strains that exhibit anti-oxidant properties and health benefits. Thus, the current review focuses on comprehending the information related to the formation of H2O2, the factors influencing it, and their pathophysiology imposed on human health. Moreover, this review also discussed the anti-oxidant potential and role of different extract of plants, Lactobacillus sp. and their fermented products in curbing H2O2‑induced oxidative stress in both in-vitro and in-vivo models via boosting the anti-oxidative activity, inhibiting of important enzyme release and downregulation of cytochrome c, cleaved caspases-3, - 8, and - 9 expression. In particular, this knowledge will assist R&D sections in biopharmaceutical and food industries in developing herbal medicine and probiotics-based or derived food products that can effectively alleviate oxidative stress issues induced by H2O2 generation.

NOX as a Therapeutic Target in Liver Disease

The nicotinamide adenine dinucleotide phosphate hydrogen oxidase (NADPH oxidase or NOX) plays a critical role in the inflammatory response and fibrosis in several organs such as the lungs, pancreas, kidney, liver, and heart. In the liver, NOXs contribute, through the generation of reactive oxygen species (ROS), to hepatic fibrosis by acting through multiple pathways, including hepatic stellate cell activation, proliferation, survival, and migration of hepatic stellate cells; hepatocyte apoptosis, enhancement of fibrogenic mediators, and mediation of an inflammatory cascade in both Kupffer cells and hepatic stellate cells. ROS are overwhelmingly produced during malignant transformation and hepatic carcinogenesis (HCC), creating an oxidative microenvironment that can cause different and various types of cellular stress, including DNA damage, ER stress, cell death of damaged hepatocytes, and oxidative stress. NOX1, NOX2, and NOX4, members of the NADPH oxidase family, have been linked to the production of ROS in the liver. This review will analyze some diseases related to an increase in oxidative stress and its relationship with the NOX family, as well as discuss some therapies proposed to slow down or control the disease's progression.

CCAAT/Enhancer-Binding Proteins in Fibrosis: Complex Roles Beyond Conventional Understanding

CCAAT/enhancer-binding proteins (C/EBPs) are a family of at least six identified transcription factors that contain a highly conserved basic leucine zipper domain and interact selectively with duplex DNA to regulate target gene expression. C/EBPs play important roles in various physiological processes, and their abnormal function can lead to various diseases. Recently, accumulating evidence has demonstrated that aberrant C/EBP expression or activity is closely associated with the onset and progression of fibrosis in several organs and tissues. During fibrosis, various C/EBPs can exert distinct functions in the same organ, while the same C/EBP can exert distinct functions in different organs. Modulating C/EBP expression or activity could regulate various molecular processes to alleviate fibrosis in multiple organs; therefore, novel C/EBPs-based therapeutic methods for treating fibrosis have attracted considerable attention. In this review, we will explore the features of C/EBPs and their critical functions in fibrosis in order to highlight new avenues for the development of novel therapies targeting C/EBPs.

MiR-155 Dysregulation Is Associated with the Augmentation of ROS/p53 Axis of Fibrosis in Thioacetamide-Induced Hepatotoxicity and Is Protected by Resveratrol

Liver fibrosis is a hallmark of thioacetamide (TAA) intoxications. MicroRNAs (miRs), such as miR-155, have been implied in the pathogenesis of liver disease, and regulated by the antioxidant and anti-inflammatory compound resveratrol (RES). The link between reactive oxygen species (ROS), tumour suppressor p53 (p53), and liver fibrosis-during the pathogenesis of TAA-induced liver injury-associated with miR-155 dysregulation with and without RES incorporation has not been previously studied. Therefore, one group of rats received TAA injections of 200 mg/kg; twice a week at the beginning of week 3 for 8 weeks (TAA group; or model group), whereas the protective group was pretreated daily with RES suspension (20 mg/kg; orally) for the first two weeks and subsequently sustained on receiving both RES and TAA until being sacrificed at the 10th week. Liver injuries developed in the model group were confirmed by a significant (p < 0.0001) elevation of hepatic tissue levels of miR-155, ROS, p53, and the profibrogenic biomarkers: tissue inhibitor of metalloproteinases-1 and α-smooth muscle actin, as well as collagen deposition (fibrosis). All these parameters were significantly (p ≤ 0.0234) protected by resveratrol (RES + TAA). In addition, we observed a significant (p < 0.0001) correlation between ROS/p53 axis mediated liver fibrosis and miR-155. Thus, TAA intoxication induced miR-155 imbalance and ROS/p53-mediated liver fibrosis, with resveratrol, conversely displaying beneficial hepatic pleiotropic effects for a period of 10 weeks.

Hepatic Myofibroblasts: A Heterogeneous and Redox-Modulated Cell Population in Liver Fibrogenesis

During chronic liver disease (CLD) progression, hepatic myofibroblasts (MFs) represent a unique cellular phenotype that plays a critical role in driving liver fibrogenesis and then fibrosis. Although they could originate from different cell types, MFs exhibit a rather common pattern of pro-fibrogenic phenotypic responses, which are mostly elicited or sustained both by oxidative stress and reactive oxygen species (ROS) and several mediators (including growth factors, cytokines, chemokines, and others) that often operate through the up-regulation of the intracellular generation of ROS. In the present review, we will offer an overview of the role of MFs in the fibrogenic progression of CLD from different etiologies by focusing our attention on the direct or indirect role of ROS and, more generally, oxidative stress in regulating MF-related phenotypic responses. Moreover, this review has the purpose of illustrating the real complexity of the ROS modulation during CLD progression. The reader will have to keep in mind that a number of issues are able to affect the behavior of the cells involved: a) the different concentrations of reactive species, b) the intrinsic state of the target cells, as well as c) the presence of different growth factors, cytokines, and other mediators in the extracellular microenvironment or of other cellular sources of ROS.

Species-specific sensitivity to TGFβ signaling and changes to the Mmp13 promoter underlie avian jaw development and evolution

Precise developmental control of jaw length is critical for survival, but underlying molecular mechanisms remain poorly understood. The jaw skeleton arises from neural crest mesenchyme (NCM), and we previously demonstrated that these progenitor cells express more bone-resorbing enzymes including Matrix metalloproteinase 13 (Mmp13) when they generate shorter jaws in quail embryos versus longer jaws in duck. Moreover, if we inhibit bone resorption or Mmp13, we can increase jaw length. In the current study, we uncover mechanisms establishing species-specific levels of Mmp13 and bone resorption. Quail show greater activation of and sensitivity to transforming growth factor beta (TGFβ) signaling than duck; where intracellular mediators like SMADs and targets like Runt-related transcription factor 2 (Runx2), which bind Mmp13, become elevated. Inhibiting TGFβ signaling decreases bone resorption, and overexpressing Mmp13 in NCM shortens the duck lower jaw. To elucidate the basis for this differential regulation, we examine the Mmp13 promoter. We discover a SMAD-binding element and single nucleotide polymorphisms (SNPs) near a RUNX2-binding element that distinguish quail from duck. Altering the SMAD site and switching the SNPs abolish TGFβ sensitivity in the quail Mmp13 promoter but make the duck promoter responsive. Thus, differential regulation of TGFβ signaling and Mmp13 promoter structure underlie avian jaw development and evolution.

PAI-1: A Major Player in the Vascular Dysfunction in Obstructive Sleep Apnea?

Obstructive sleep apnea is a chronic and prevalent condition that is associated with endothelial dysfunction, atherosclerosis, and imposes excess overall cardiovascular risk and mortality. Despite its high prevalence and the susceptibility of CVD patients to OSA-mediated stressors, OSA is still under-recognized and untreated in cardiovascular practice. Moreover, conventional OSA treatments have yielded either controversial or disappointing results in terms of protection against CVD, prompting the need for the identification of additional mechanisms and associated adjuvant therapies. Plasminogen activator inhibitor-1 (PAI-1), the primary inhibitor of tissue-type plasminogen activator (tPA) and urinary-type plasminogen activator (uPA), is a key regulator of fibrinolysis and cell migration. Indeed, elevated PAI-1 expression is associated with major cardiovascular adverse events that have been attributed to its antifibrinolytic activity. However, extensive evidence indicates that PAI-1 can induce endothelial dysfunction and atherosclerosis through complex interactions within the vasculature in an antifibrinolytic-independent matter. Elevated PAI-1 levels have been reported in OSA patients. However, the impact of PAI-1 on OSA-induced CVD has not been addressed to date. Here, we provide a comprehensive review on the mechanisms by which OSA and its most detrimental perturbation, intermittent hypoxia (IH), can enhance the transcription of PAI-1. We also propose causal pathways by which PAI-1 can promote atherosclerosis in OSA, thereby identifying PAI-1 as a potential therapeutic target in OSA-induced CVD.

Upper Gastrointestinal Cancer and Liver Cirrhosis

Simple Summary

There is a higher incidence rate of upper gastrointestinal cancer in those with liver cirrhosis. The contributing factors include gastric ulcers, congestive gastropathy, zinc deficiency, alcohol drinking, tobacco use and gut microbiota. Most of the de novo malignancies that develop after liver transplantation for cirrhotic patients are upper gastrointestinal cancers. The surgical risk of upper gastrointestinal cancers in cirrhotic patients with advanced liver cirrhosis is higher.

Abstract

The extended scope of upper gastrointestinal cancer can include esophageal cancer, gastric cancer and pancreatic cancer. A higher incidence rate of gastric cancer and esophageal cancer in patients with liver cirrhosis has been reported. It is attributable to four possible causes which exist in cirrhotic patients, including a higher prevalence of gastric ulcers and congestive gastropathy, zinc deficiency, alcohol drinking and tobacco use and coexisting gut microbiota. Helicobacter pylori infection enhances the development of gastric cancer. In addition, Helicobacter pylori, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans also contribute to the development of pancreatic cancer in cirrhotic patients. Cirrhotic patients (especially those with alcoholic liver cirrhosis) who undergo liver transplantation have a higher overall risk of developing de novo malignancies. Most de novo malignancies are upper gastrointestinal malignancies. The prognosis is usually poor. Considering the surgical risk of upper gastrointestinal cancer among those with liver cirrhosis, a radical gastrectomy with D1 or D2 lymph node dissection can be undertaken in Child class A patients. D1 lymph node dissection can be performed in Child class B patients. Endoscopic submucosal dissection for gastric cancer or esophageal cancer can be undertaken safely in selected cirrhotic patients. In Child class C patients, a radical gastrectomy is potentially fatal. Pancreatic radical surgery should be avoided in those with liver cirrhosis with Child class B or a MELD score over 15. The current review focuses on the recent reports on some factors in liver cirrhosis that contribute to the development of upper gastrointestinal cancer. Quitting alcohol drinking and tobacco use is important. How to decrease the risk of the development of gastrointestinal cancer in those with liver cirrhosis remains a challenging problem.

Oxidative Stress and Redox Signaling in the Pathophysiology of Liver Diseases

The increased production of derivatives of molecular oxygen and nitrogen in the form of reactive oxygen species (ROS) and reactive nitrogen species (RNS) lead to molecular damage called oxidative stress. Under normal physiological conditions, the ROS generation is tightly regulated in different cells and cellular compartments. Any disturbance in the balance between the cellular generation of ROS and antioxidant balance leads to oxidative stress. In this article, we discuss the sources of ROS (endogenous and exogenous) and antioxidant mechanisms. We also focus on the pathophysiological significance of oxidative stress in various cell types of the liver. Oxidative stress is implicated in the development and progression of various liver diseases. We narrate the master regulators of ROS-mediated signaling and their contribution to liver diseases. Nonalcoholic fatty liver diseases (NAFLD) are influenced by a "multiple parallel-hit model" in which oxidative stress plays a central role. We highlight the recent findings on the role of oxidative stress in the spectrum of NAFLD, including fibrosis and liver cancer. Finally, we provide a brief overview of oxidative stress biomarkers and their therapeutic applications in various liver-related disorders. Overall, the article sheds light on the significance of oxidative stress in the pathophysiology of the liver. © 2022 American Physiological Society. Compr Physiol 12:3167-3192, 2022.

Capacity of extracellular globins to reduce liver fibrosis via scavenging reactive oxygen species and promoting MMP-1 secretion

Background & aims

Hepatic stellate cells (HSCs) are the primary cell type in liver fibrosis, a significant global health care burden. Cytoglobin (CYGB), a globin family member expressed in HSCs, inhibits HSC activation and reduces collagen production. We studied the antifibrotic properties of globin family members hemoglobin (HB), myoglobin (MB), and neuroglobin (NGB) in comparison with CYGB.

Approach & results

We characterized the biological activities of globins in cultured human HSCs (HHSteCs) and their effects on carbon tetrachloride (CCl₄)-induced cirrhosis in mice. All globins demonstrated greater antioxidant capacity than glutathione in cell-free systems. Cellular fractionation revealed endocytosis of extracellular MB, NGB, and CYGB, but not HB; endocytosed globins localized to intracellular membranous, cytoplasmic, and cytoskeletal fractions. MB, NGB, and CYGB, but not HB, scavenged reactive oxygen species generated spontaneously or stimulated by H₂O₂ or transforming growth factor β1 in HHSteCs and reduced collagen 1A1 production via suppressing COL1A1 promoter activity. Disulfide bond-mutant NGB displayed decreased heme and superoxide scavenging activity and reduced collagen inhibitory capacity. RNA sequencing of MB- and NGB-treated HHSteCs revealed downregulation of extracellular matrix–encoding and fibrosis-related genes and HSC deactivation markers. Upregulation of matrix metalloproteinase (MMP)-1 was observed following MB and NGB treatment, and MMP-1 knockdown partially reversed globin-mediated effects on secreted collagen. Importantly, administration of MB, NGB, and CYGB suppressed CCl₄-induced mouse liver fibrosis.

Conclusions

These findings revealed unexpected roles for MB and NGB in deactivating HSCs and inhibiting liver fibrosis development, suggesting that globin therapy may represent a new strategy for combating fibrotic liver disease.

Myoglobin, neuroglobin, and cytoglobin, but not hemoglobin:•

Internalize into human hepatic stellate cells via endocytosis pathway.

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Scavenge intracellular reactive oxidative species.

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Suppress COL1A1 promoter activity and promote matrix metaloproteinase-1 secretion.

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Suppress carbon tetrachloride-induced mouse liver fibrosis.

Molecular Mechanisms and Potential New Therapeutic Drugs for Liver Fibrosis

Liver fibrosis is the pathological process of excessive extracellular matrix deposition after liver injury and is a precursor to cirrhosis, hepatocellular carcinoma (HCC). It is essentially a wound healing response to liver tissue damage. Numerous studies have shown that hepatic stellate cells play a critical role in this process, with various cells, cytokines, and signaling pathways engaged. Currently, the treatment targeting etiology is considered the most effective measure to prevent and treat liver fibrosis, but reversal fibrosis by elimination of the causative agent often occurs too slowly or too rarely to avoid life-threatening complications, especially in advanced fibrosis. Liver transplantation is the only treatment option in the end-stage, leaving us with an urgent need for new therapies. An in-depth understanding of the mechanisms of liver fibrosis could identify new targets for the treatment. Most of the drugs targeting critical cells and cytokines in the pathogenesis of liver fibrosis are still in pre-clinical trials and there are hardly any definitive anti-fibrotic chemical or biological drugs available for clinical use. In this review, we will summarize the pathogenesis of liver fibrosis, focusing on the role of key cells, associated mechanisms, and signaling pathways, and summarize various therapeutic measures or drugs that have been trialed in clinical practice or are in the research stage.

Identification of the Molecular Basis of Nanocurcumin-Induced Telocyte Preservation within the Colon of Ulcerative Colitis Rat Model

Background

Telocytes (TCs) are a distinct type of interstitial cells that play a vital role in the pathogenesis of ulcerative colitis and colonic tissue hemostasis. The aim of this study was to examine the effect of nanocurcumin (NC) on the morphometric and immunohistochemical characterization of TCs in the ulcerative colitis (UC) rat model.

Methods

Forty rats were randomly divided into control, NC, UC, and UC+NC groups. At the end of the experiment, the colon was dissected and prepared for histopathological and immunohistochemical assessment. Tissue homogenates were prepared for real-time PCR assessment of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and transforming growth factor-beta (TGF-β) gene expression. Our results revealed extensive mucosal damage with inflammatory cell infiltration, significant reduction of CD34, and vimentin immunostained TCs in the colon of the UC group with significant elevation of expression of IL-6, TNF-α, and TGF-β. The UC+NC-treated group revealed significant elevation of TC count compared to the UC group besides, a significant reduction of the three gene expression.

Conclusion

NC successfully targeted the colonic tissue, improved the mucosal lesion, preserve TCs distribution, and count through its anti-inflammatory and fibrinolytic properties.

Activation of transmembrane receptor tyrosine kinase DDR1-STAT3 cascade by extracellular matrix remodeling promotes liver metastatic colonization in uveal melanoma

Colonization is believed a rate-limiting step of metastasis cascade. However, its underlying mechanism is not well understood. Uveal melanoma (UM), which is featured with single organ liver metastasis, may provide a simplified model for realizing the complicated colonization process. Because DDR1 was identified to be overexpressed in UM cell lines and specimens, and abundant pathological deposition of extracellular matrix collagen, a type of DDR1 ligand, was noted in the microenvironment of liver in metastatic patients with UM, we postulated the hypothesis that DDR1 and its ligand might ignite the interaction between UM cells and their surrounding niche of liver thereby conferring strengthened survival, proliferation, stemness and eventually promoting metastatic colonization in liver. We tested this hypothesis and found that DDR1 promoted these malignant cellular phenotypes and facilitated metastatic colonization of UM in liver. Mechanistically, UM cells secreted TGF-β1 which induced quiescent hepatic stellate cells (qHSCs) into activated HSCs (aHSCs) which secreted collagen type I. Such a remodeling of extracellular matrix, in turn, activated DDR1, strengthening survival through upregulating STAT3-dependent Mcl-1 expression, enhancing stemness via upregulating STAT3-dependent SOX2, and promoting clonogenicity in cancer cells. Targeting DDR1 by using 7rh, a specific inhibitor, repressed proliferation and survival in vitro and in vivo outgrowth. More importantly, targeting cancer cells by pharmacological inactivation of DDR1 or targeting microenvironmental TGF-β1-collagen I loop exhibited a prominent anti-metastasis effect in mice. In conclusion, targeting DDR1 signaling and TGF-β signaling may be a novel approach to diminish hepatic metastasis in UM.

The Power of Plasticity-Metabolic Regulation of Hepatic Stellate Cells

Hepatic stellate cells (HSCs) are resident non-parenchymal liver pericytes whose plasticity enables them to regulate a remarkable range of physiologic and pathologic responses. To support their functions in health and disease, HSCs engage pathways regulating carbohydrate, mitochondrial, lipid, and retinoid homeostasis. In chronic liver injury, HSCs drive hepatic fibrosis and are implicated in inflammation and cancer. To do so, the cells activate, or transdifferentiate, from a quiescent state into proliferative, motile myofibroblasts that secrete extracellular matrix, which demands rapid adaptation to meet a heightened energy need. Adaptations include reprogramming of central carbon metabolism, enhanced mitochondrial number and activity, endoplasmic reticulum stress, and liberation of free fatty acids through autophagy-dependent hydrolysis of retinyl esters that are stored in cytoplasmic droplets. As an archetype for pericytes in other tissues, recognition of the HSC's metabolic drivers and vulnerabilities offer the potential to target these pathways therapeutically to enhance parenchymal growth and modulate repair.

N-acetylcysteine maintains penile length and erectile function in bilateral cavernous nerve crush rat model by reducing penile fibrosis

Penile length shortening and erectile dysfunction are common complications after radical prostatectomy. Various methods have been used to maintain erectile function, but less attention has been paid to preserving penis length. N-acetylcysteine (NAC) has the effect of antioxidation and antifibrotic, which may be beneficial to improve those postoperative complications. This study investigated the effect of NAC on maintaining the penile length and the erectile function after bilateral cavernous nerve crush (BCNC) and its underlying mechanism. Twenty-four male rats were randomly divided into three groups: control group, BCNC group, and BCNC + NAC group. NAC or equal volume of saline was daily administrated by intragastric gavage for 4 weeks. The initial and end penile lengths were measured. Intracavernosal pressure/mean arterial pressure (ICP/MAP) ratio was calculated to assess erectile function. Hematoxylin–eosin staining, Masson's trichrome staining, immunohistochemistry, and Western blot were performed to explore cellular and molecular changes of the penis. Compared to the BCNC group, the penile length, ICP/MAP ratio and smooth muscle/collagen ratio in the BCNC + NAC group were improved significantly (all P < 0.05), and the expressions of endothelial nitric oxide synthase, α-smooth muscle actin, glutathione, and glutathione peroxidase 1 were significantly increased after NAC treated (all P < 0.05), along with the decreased expressions of hypoxia-inducible factor-1α, transforming growth factor-β1, collagen I, collagen III, collagen IV, malonaldehyde, and lysine oxidase (all P < 0.05). This study demonstrated that NAC could maintain penile length and partly improve erectile function. Possible mechanism is directly and/or indirectly related to antihypoxic and antifibrosis.

Activation of Hepatic Stellate Cells Requires Dissociation of E-Cadherin-Containing Adherens Junctions with Hepatocytes

Hepatic stellate cells (HSCs) are resident mesenchymal cells in the space of Disse interposed between liver sinusoidal endothelial cells and hepatocytes. Thorn-like microprojections, or spines, project out from the cell surface of HSCs, crossing the space of Disse, to establish adherens junctions with neighboring hepatocytes. Although HSC activation is initiated largely from stimulation by adjacent cells, isolated HSCs also activate spontaneously in primary culture on plastic. Therefore, other unknown HSC-initiating factors apart from paracrine stimuli may promote activation. The dissociation of adherens junctions between HSCs and hepatocytes as an activating signal for HSCs was explored, establishing epithelial cadherin (E-cadherin) as an adhesion molecule linking hepatocytes and HSCs. In vivo, following carbon tetrachloride-induced liver injury, HSCs lost their spines and dissociated from adherens junctions in the early stages of injury, and were subsequently activated along with an increase in YAP/TAZ expression. After abrogation of liver injury, HSCs reconstructed their spines and adherens junctions. In vitro, reconstitution of E-cadherin-containing adherens junctions by forced E-cadherin expression quiesced HSCs and suppressed TAZ expression. Additionally, increase of TAZ expression leading to the activation of HSCs by autocrine stimulation of transforming growth factor-β, was revealed as a mechanism of spontaneous activation. Thus, we have uncovered a critical event required for HSC activation through enhanced TAZ-mediated mechanotransduction after the loss of adherens junctions between HSCs and hepatocytes.

Targeting Hepatic Stellate Cells for the Treatment of Liver Fibrosis by Natural Products: Is It the Dawning of a New Era?

Liver fibrosis is a progressive liver damage condition that is worth studying widely. It is important to target and alleviate the disease at an early stage before turning into later cirrhosis or liver cancer. There are currently no direct medicines targeting the attenuation or reversal of liver fibrosis, and so there is an urgent need to look into this area. Traditional Chinese Medicine has a long history in using herbal medicines to treat liver diseases including fibrosis. It is time to integrate the ancient wisdom with modern science and technology to look for the best solution to the disease. In this review, the principal concept of the pathology of liver fibrosis will be described, and then some of the single compounds isolated from herbal medicines, including salvianolic acids, oxymatrine, curcumin, tetrandrine, etc. will be discussed from their effects to the molecular mechanism behind. Molecular targets of the compounds are analyzed by network pharmacology approach, and TGFβ/SMAD was identified as the most common pathway. This review serves to summarize the current findings of herbal medicines combining with modern medicines in the area of fibrosis. It hopefully provides insights in further pharmaceutical research directions.

iRhom2 inhibits bile duct obstruction-induced liver fibrosis

Chronic liver disease can induce prolonged activation of hepatic stellate cells, which may result in liver fibrosis. Inactive rhomboid protein 2 (iRhom2) is required for the maturation of A disintegrin and metalloprotease 17 (ADAM17, also called TACE), which is responsible for the cleavage of membrane-bound tumor necrosis factor-α (TNF-α) and its receptors (TNFRs). Here, using the murine bile duct ligation (BDL) model, we showed that the abundance of iRhom2 and activation of ADAM17 increased during liver fibrosis. Consistent with this, concentrations of ADAM17 substrates were increased in plasma samples from mice after BDL and in patients suffering from liver cirrhosis. We observed increased liver fibrosis, accelerated disease progression, and an increase in activated stellate cells after BDL in mice lacking iRhom2 (Rhbdf2^-/- ) compared to that in controls. In vitro primary mouse hepatic stellate cells exhibited iRhom2-dependent shedding of the ADAM17 substrates TNFR1 and TNFR2. In vivo TNFR shedding after BDL also depended on iRhom2. Treatment of Rhbdf2^-/- mice with the TNF-α inhibitor etanercept reduced the presence of activated stellate cells and alleviated liver fibrosis after BDL. Together, these data suggest that iRhom2-mediated inhibition of TNFR signaling protects against liver fibrosis.

The Anti-Oxidation and Mechanism of Essential Oil of Paederia scandens in the NAFLD Model of Chicken

Simple Summary

The essential oil of Paederia scandens can remedy non-alcoholic fatty liver disease of chicken, but the mechanisms remain unclear. In this study, proteomics technology was used to declare the anti-non-alcoholic fatty liver disease mechanism of Paederia scandens essential oil. The results show that the essential oil of Paederia scandens significant decreased the oxidative stress of non-alcoholic fatty liver disease in chicken, which was mainly due to the center regulation protein of HSP7C being significantly inhibited.

Abstract

The aim of the study is to determine the underlying pathogenic mechanisms of oxidative stress and detect the anti-oxidative target of essential oil of Paederia scandens in non-alcoholic fatty liver disease (NAFLD). Chicken NAFLD was modeled by feeding with a high-capacity diet and Paederia scandens essential oil was used to treat the disease. The levels of hepatic reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), and the differential proteins and network of protein–protein interactions were investigated in model and drug-treated groups. The results showed that essential oil of Paederia scandens down regulated the hepatic ROS and MDA level significantly (p < 0.05 and 0.01, respectively). The heat shock cognate 71 kDa protein (HSP7C) was down regulated significantly, which was in the center of the network and interacted with 22 other proteins. The results showed that oxidative stress played an important role in the pathogenesis of chicken NAFLD. The essential oil of Paederia scandens showed good anti-oxidation activity by down regulating the HSP7C protein, which can be used as a potential therapeutic target in chicken NAFLD.

Gastrointestinal microecology: a crucial and potential target in acute pancreatitis

In the early stage of acute pancreatitis (AP), abundant cytokines induced by local pancreatic inflammation enter the bloodstream, further cause systemic inflammatory response syndrome (SIRS) by "trigger effect", which eventually leads to multiple organ dysfunction syndrome (MODS). During SIRS and MODS, the intestinal barrier function was seriously damaged accompanied by the occurrence of gut-derived infection which forms a "second hit summit" by inflammatory overabundance. Gastrointestinal microecology, namely the biologic barrier, could be transformed into a pathogenic state, which is called microflora dysbiosis when interfered by the inflammatory stress during AP. More and more evidences indicate that gastrointestinal microflora dysbiosis plays a key role in "the second hit" induced by AP gut-derived infection. Therefore, the maintenance of gastrointestinal microecology balance is likely to provide an effective method in modulating systemic infection of AP. This article reviewed the progress of gastrointestinal microecology in AP to provide a reference for deeply understanding the pathogenic mechanisms of AP and identifying new therapeutic targets.

Transforming growth factor β (TGFβ) cross-talk with the unfolded protein response is critical for hepatic stellate cell activation

Transforming growth factor β (TGFβ) potently activates hepatic stellate cells (HSCs), which promotes production and secretion of extracellular matrix (ECM) proteins and hepatic fibrogenesis. Increased ECM synthesis and secretion in response to TGFβ is associated with endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). TGFβ and UPR signaling pathways are tightly intertwined during HSC activation, but the regulatory mechanism that connects these two pathways is poorly understood. Here, we found that TGFβ treatment of immortalized HSCs (i.e. LX-2 cells) induces phosphorylation of the UPR sensor inositol-requiring enzyme 1α (IRE1α) in a SMAD2/3-procollagen I-dependent manner. We further show that IRE1α mediates HSC activation downstream of TGFβ and that its role depends on activation of a signaling cascade involving apoptosis signaling kinase 1 (ASK1) and c-Jun N-terminal kinase (JNK). ASK1-JNK signaling promoted phosphorylation of the UPR-associated transcription factor CCAAT/enhancer binding protein β (C/EBPβ), which is crucial for TGFβ- or IRE1α-mediated LX-2 activation. Pharmacological inhibition of C/EBPβ expression with the antiviral drug adefovir dipivoxil attenuated TGFβ-mediated activation of LX-2 or primary rat HSCs in vitro and hepatic fibrogenesis in vivo Finally, we identified a critical relationship between C/EBPβ and the transcriptional regulator p300 during HSC activation. p300 knockdown disrupted TGFβ- or UPR-induced HSC activation, and pharmacological inhibition of the C/EBPβ-p300 complex decreased TGFβ-induced HSC activation. These results indicate that TGFβ-induced IRE1α signaling is critical for HSC activation through a C/EBPβ-p300-dependent mechanism and suggest C/EBPβ as a druggable target for managing fibrosis.

NADPH oxidase 5 promotes proliferation and fibrosis in human hepatic stellate cells

NADPH oxidase (Nox) variants Nox1, Nox2 and Nox4 are implicated in the progression of liver fibrosis. However, the role of Nox5 is not yet known, mainly due to the lack of this enzyme in rat and mouse genomes. Here we describe the expression and functional relevance of Nox5 in the human cell line of hepatic stellate cells (HSC) LX-2. Under basal conditions, three long (Nox5-L: Nox5α, -β, and -δ) and a short (Nox5-S or Nox5ε) splice variants were detected, which were silenced with specific siRNAs for Nox5. The most abundant isoform was Nox5-S, accounting for more than 90% of Nox5 protein. Overexpression of Nox5β generated reactive oxygen species (ROS) in the presence of calcium, as judged by the production of hydrogen peroxide, L-012 luminescence and cytochrome c reduction. Nox5ε did not generated ROS under these conditions, and a reduced ROS production was observed when co-expressed with Nox5β. In contrast, dihydroethidium oxidation was increased by Nox5β or Nox5ε, suggesting that Nox5ε induced intracellular oxidative stress by an unknown mechanism. Functional studies showed that both Nox5β and Nox5ε stimulated the proliferation of LX-2 cells and the collagen type I levels, while Nox5 siRNAs inhibited these effects. Interestingly, TGF-β and angiotensin II upregulated Nox5 expression, which was reduced in cells pre-incubated with catalase. Further studies silencing Nox5 in TGF-β-treated cells resulted in a reduction of collagen levels via p38 MAPK. Collectively, these results show for the first time that Nox5 can play a relevant role in the proliferation and fibrosis on human HSC.

Inorganic Nanomaterials as Highly Efficient Inhibitors of Cellular Hepatic Fibrosis

Chronic liver dysfunction usually begins with hepatic fibrosis. To date, no effective anti-fibrotic drugs have been approved for clinical use in humans. In the current work, titanium dioxide (TiO₂) nanoparticles (NPs) and silicon dioxide (SiO₂) NPs are used as active inhibitors with intrinsic chemico-physico properties to block fibrosis and the associated phenotypes through acting on hepatic stellate cells (HSCs, the liver machinery for depositing scar tissues seen in fibrosis). Using LX-2 cells as the HSC model, internalized nanomaterials are found to suppress classical outcomes of cellular fibrosis, for example, inhibiting the expression of collagen I (Col-I) and alpha smooth muscle actin (α-SMA), initiated by transforming growth factor β (TGF-β)-activated HSCs in both a concentration-dependent and a time-dependent manner. Biochemically, these nanomaterials could also facilitate the proteolytic breakdown of collagen by up-regulation of matrix metalloproteinases (MMPs) and down-regulation of tissue inhibitors of MMPs (TIMPs). Furthermore, through regulating epithelial-mesenchymal transition (EMT) genes [e.g., E-cadherin (E-Cad) and N-cadherin (N-Cad)], the adhesion and migration profiles of TGF-β-activated LX-2 cells treated with nanomaterials were further inhibited, reverting them to a more quiescent state. Thus, the collective results pave the new way that nanomaterials can be used as potential therapeutic inhibitors for the treatment of in vivo fibrosis.

Hydrogen peroxide (H2O2): a review of its use in surgery

Hydrogen peroxide has been used in medicine for more than 100 years. It is known in surgery as a highly useful irrigation solution by virtue of both its hemostatic and its antimicrobial effects. Due to its possible negative effect on wound healing and its cytotoxic effect in higher concentrations, there are concerns about the safety of its use. The objective of this paper is to review the safety and beneficial effects of hydrogen peroxide.

Food components with antifibrotic activity and implications in prevention of liver disease

Increasing prevalence of nonalcoholic fatty liver disease (NAFLD) in parallel with the obesity epidemic has been a major public health concern. NAFLD is the most common chronic liver disease in the United States, ranging from fatty liver to steatohepatitis, fibrosis and cirrhosis in the liver. In response to chronic liver injury, fibrogenesis in the liver occurs as a protective response; however, prolonged and dysregulated fibrogenesis can lead to liver fibrosis, which can further progress to cirrhosis and eventually hepatocellular carcinoma. Interplay of hepatocytes, macrophages and hepatic stellate cells (HSCs) in the hepatic inflammatory and oxidative milieu is critical for the development of NAFLD. In particular, HSCs play a major role in the production of extracellular matrix proteins. Studies have demonstrated that bioactive food components and natural products, including astaxanthin, curcumin, blueberry, silymarin, coffee, vitamin C, vitamin E, vitamin D, resveratrol, quercetin and epigallocatechin-3-gallate, have antifibrotic effects in the liver. This review summarizes current knowledge of the mechanistic insight into the antifibrotic actions of the aforementioned bioactive food components.

COL1A1, PRPF40A, and UCP2 correlate with hypoxia markers in non-small cell lung cancer

Purpose

Collagen 1A1 (COL1A1), RNA-binding and pre-mRNA Processing Factor (PRPF40A), and Uncoupling Protein 2 (UCP2) were identified as downstream effectors of cytoglobin (CYGB), which was shown implicated in tumour biology. Although these three genes have been previously associated with cancer, little is known about their status in lung malignancies.

Methods

Hereby, we investigated the expression and promoter methylation of COL1A1, PRPF40A, and UCP2 in 156 non-small cell lung cancer (NSCLC) and adjacent normal tissues.

Results

We demonstrate that COL1A1 and PRPF40A mRNAs are significantly overexpressed in NSCLC (p < 1 × 10⁻⁴), while UCP2 exhibits a trend of upregulation (p = 0.066). Only COL1A1 promoter revealed hypermethylation in NSCLCs (36%), which was particularly evident in squamous cell carcinomas (p = 0.024) and in the tumours with moderate-to-good differentiation (p = 0.01). Transcript level of COL1A1, as well as PRPF40A and UCP2, exhibited striking association (p ≤ 0.001) with the expression of hypoxia markers. In addition, we demonstrate in lung cancer cell lines exposed to hypoxia or oxidative stress that COL1A1 transcription significantly responds to oxygen depletion, while other genes showed the modest upregulation in stress conditions.

Conclusion

In conclusion, our data revealed that COL1A1, UCP2, and PRPF40A are novel players implicated in the complex network of hypoxia response in NSCLC.

Liver fibrosis and hepatic stellate cells: Etiology, pathological hallmarks and therapeutic targets

Liver fibrosis is a reversible wound-healing process aimed at maintaining organ integrity, and presents as the critical pre-stage of liver cirrhosis, which will eventually progress to hepatocellular carcinoma in the absence of liver transplantation. Fibrosis generally results from chronic hepatic injury caused by various factors, mainly viral infection, schistosomiasis, and alcoholism; however, the exact pathological mechanisms are still unknown. Although numerous drugs have been shown to have antifibrotic activity in vitro and in animal models, none of these drugs have been shown to be efficacious in the clinic. Importantly, hepatic stellate cells (HSCs) play a key role in the initiation, progression, and regression of liver fibrosis by secreting fibrogenic factors that encourage portal fibrocytes, fibroblasts, and bone marrow-derived myofibroblasts to produce collagen and thereby propagate fibrosis. These cells are subject to intricate cross-talk with adjacent cells, resulting in scarring and subsequent liver damage. Thus, an understanding of the molecular mechanisms of liver fibrosis and their relationships with HSCs is essential for the discovery of new therapeutic targets. This comprehensive review outlines the role of HSCs in liver fibrosis and details novel strategies to suppress HSC activity, thereby providing new insights into potential treatments for liver fibrosis.

Liver fibrosis and hepatic stellate cells: Etiology, pathological hallmarks and therapeutic targets

Liver fibrosis is a reversible wound-healing process aimed at maintaining organ integrity, and presents as the critical pre-stage of liver cirrhosis, which will eventually progress to hepatocellular carcinoma in the absence of liver transplantation. Fibrosis generally results from chronic hepatic injury caused by various factors, mainly viral infection, schistosomiasis, and alcoholism; however, the exact pathological mechanisms are still unknown. Although numerous drugs have been shown to have antifibrotic activity in vitro and in animal models, none of these drugs have been shown to be efficacious in the clinic. Importantly, hepatic stellate cells (HSCs) play a key role in the initiation, progression, and regression of liver fibrosis by secreting fibrogenic factors that encourage portal fibrocytes, fibroblasts, and bone marrow-derived myofibroblasts to produce collagen and thereby propagate fibrosis. These cells are subject to intricate cross-talk with adjacent cells, resulting in scarring and subsequent liver damage. Thus, an understanding of the molecular mechanisms of liver fibrosis and their relationships with HSCs is essential for the discovery of new therapeutic targets. This comprehensive review outlines the role of HSCs in liver fibrosis and details novel strategies to suppress HSC activity, thereby providing new insights into potential treatments for liver fibrosis.

Co-infections with liver fluke and Helicobacter species: A paradigm change in pathogenesis of opisthorchiasis and cholangiocarcinoma?

Infection with the fish-borne liver fluke Opisthorchis viverrini is classified by the International Agency for Research on Cancer as a Group 1 carcinogen: definitely carcinogenic in humans. Cofactors likely contribute to bile duct cancer (cholangiocarcinoma) caused by this infection. Here we review recent findings that address the role of liver fluke associated H. pylori in hepatobiliary disease and malignancy. We hypothesize that co-infection by O. viverrini and the bacillus Helicobacter pylori is central of liver fluke infection associated cholangiocarcinoma.

Epigenetic regulation of hepatic stellate cell activation and liver fibrosis

Chronic liver injury to hepatocytes or cholangiocytes, when left unmanaged, leads to the development of liver fibrosis, a condition characterized by the excessive intrahepatic deposition of extracellular matrix proteins. Activated hepatic stellate cells constitute the predominant source of extracellular matrix in fibrotic livers and their transition from a quiescent state during fibrogenesis is associated with important alterations in their transcriptional and epigenetic landscape. Areas covered: We briefly describe the processes involved in hepatic stellate cell activation and discuss our current understanding of alterations in the epigenetic landscape, i.e DNA methylation, histone modifications and the functional role of non-coding RNAs that accompany this key event in the development of chronic liver disease. Expert commentary: Although great progress has been made, our understanding of the epigenetic regulation of hepatic stellate cell activation is limited and, thus far, insufficient to allow the development of epigenetic drugs that can selectively interrupt liver fibrosis.

Cartilage oligomeric matrix protein participates in the pathogenesis of liver fibrosis

BACKGROUND & AIMS

Liver fibrosis is characterized by significant accumulation of extracellular matrix (ECM) proteins, mainly fibrillar collagen-I, as a result of persistent liver injury. Cartilage oligomeric matrix protein (COMP) is largely found in the ECM of skeletal tissue. Increased COMP expression has been associated with fibrogenesis in systemic sclerosis, lung fibrosis, chronic pancreatitis, cirrhosis and hepatocellular carcinoma. We hypothesized that COMP could induce fibrillar collagen-I deposition and participate in matrix remodeling thus contributing to the pathophysiology of liver fibrosis.

METHODS

Thioacetamide (TAA) and carbon tetrachloride (CCl4) were used to induce liver fibrosis in wild-type (WT) and Comp-/- mice. In vitro experiments were performed with primary hepatic stellate cells (HSCs).

RESULTS

COMP expression was detected in livers from control WT mice and was upregulated in response to either TAA or CCl4-induced liver fibrosis. TAA-treated or CCl4-injected Comp-/- mice showed less liver injury, inflammation and fibrosis compared to their corresponding control WT mice. Challenge of HSCs with recombinant COMP (rCOMP) induced intra- plus extracellular collagen-I deposition and increased matrix metalloproteinases (MMPs) 2, 9 and 13, albeit similar expression of transforming growth factor beta (TGFβ) protein, in addition to Tgfβ, tumour necrosis factor alpha (Tnfα) and tissue inhibitor of metalloproteinases-1 (Timp1) mRNAs. We demonstrated that COMP binds collagen-I; yet, it does not prevent collagen-I cleavage by MMP1. Last, rCOMP induced collagen-I expression in HSCs via CD36 receptor signaling and activation of the MEK1/2-pERK1/2 pathway.

CONCLUSION

These results suggest that COMP contributes to liver fibrosis by regulating collagen-I deposition.

LAY SUMMARY

Cartilage oligomeric matrix protein (COMP) induces fibrillar collagen-I deposition via the CD36 receptor signaling and activation of the MEK1/2-pERK1/2 pathway, and participates in extracellular matrix remodeling contributing to the pathophysiology of liver fibrosis.

DNA methylation in fibrosis

Fibrosis is characterised by an exuberant wound healing response and the major cell type responsible is the myofibroblast. The myofibroblast is typified by excessive ECM production and contractile activity and is demarcated by alpha-smooth muscle actin expression. What has recently come to light is that the activation of the fibroblast to myofibroblast may be under epigenetic control, specifically methylation. Methylation of DNA is a conserved mechanism to precisely regulate gene expression in a specific context. Hypermethylation leads to gene repression and hypomethylation results in gene induction. Methylation abnormalities have recently been uncovered in fibrosis, both organ specific and widespread fibrosis. The fact that these methylation changes are rapid and reversible lends themselves amenable to therapeutic intervention. This review considers the role of methylation in fibrosis and the activation of the myofibroblasts and how this could be targeted for fibrosis. Fibrosis is of course currently intractable to therapeutics and is a leading cause of morbidity and mortality and is an urgent unmet clinical need.

Hepatoprotective and Anti-fibrotic Agents: It's Time to Take the Next Step

Hepatic fibrosis and cirrhosis cause strong human suffering and necessitate a monetary burden worldwide. Therefore, there is an urgent need for the development of therapies. Pre-clinical animal models are indispensable in the drug discovery and development of new anti-fibrotic compounds and are immensely valuable for understanding and proofing the mode of their proposed action. In fibrosis research, inbreed mice and rats are by far the most used species for testing drug efficacy. During the last decades, several hundred or even a thousand different drugs that reproducibly evolve beneficial effects on liver health in respective disease models were identified. However, there are only a few compounds (e.g., GR-MD-02, GM-CT-01) that were translated from bench to bedside. In contrast, the large number of drugs successfully tested in animal studies is repeatedly tested over and over engender findings with similar or identical outcome. This circumstance undermines the 3R (Replacement, Refinement, Reduction) principle of Russell and Burch that was introduced to minimize the suffering of laboratory animals. This ethical framework, however, represents the basis of the new animal welfare regulations in the member states of the European Union. Consequently, the legal authorities in the different countries are halted to foreclose testing of drugs in animals that were successfully tested before. This review provides a synopsis on anti-fibrotic compounds that were tested in classical rodent models. Their mode of action, potential sources and the observed beneficial effects on liver health are discussed. This review attempts to provide a reference compilation for all those involved in the testing of drugs or in the design of new clinical trials targeting hepatic fibrosis.

Hic-5 deficiency attenuates the activation of hepatic stellate cells and liver fibrosis through upregulation of Smad7 in mice

BACKGROUND & AIM

Hydrogen peroxide-inducible clone-5 (Hic-5), also named as transforming growth factor beta-1-induced transcript 1 protein (Tgfb1i1), was found to be induced by TGF-β. Previous studies have shown that TGF-β is a principal mediator of hepatic stellate cell (HSC) activation in liver fibrosis. However, this process remains elusive. In this study, we aimed to define the role of Hic-5 in HSC activation and liver fibrosis.

METHODS

We examined the expression levels of Hic-5 during HSCs activation and in fibrotic liver tissues by quantitative real-time reverse transcriptase polymerase chain reaction, Western blot and immunohistochemistry. Hic-5 knockout (KO) and wild-type (WT) mice were subjected to bile duct ligation (BDL) or carbon tetrachloride (CCl4) injection to induce liver fibrosis.

RESULTS

Hic-5 expression was strongly upregulated in activated HSCs of the human fibrotic liver tissue and BDL or CCl4-induced mouse liver fibrosis. Hic-5 deficiency significantly attenuated mouse liver fibrosis and HSC activation. Furthermore, Hic-5 knockdown by siRNA in vivo repressed CCl4-induced liver fibrosis in mice. Mechanistically, the absence of Hic-5 significantly inhibited the TGF-β/Smad2 signaling pathway, proved by increasing Smad7 expression, resulting in reduced collagen production and α-smooth muscle actin expression in the activated HSCs.

CONCLUSION

Hic-5 deficiency attenuates the activation of HSCs and liver fibrosis though reducing the TGF-β/Smad2 signaling by upregulation of Smad7. Thus, Hic-5 can be regarded as a potential therapeutic target for liver fibrosis.

Profiling of concanavalin A-binding glycoproteins in human hepatic stellate cells activated with transforming growth factor-β1

Glycoproteins play important roles in maintaining normal cell functions depending on their glycosylations. Our previous study indicated that the abundance of glycoproteins recognized by concanavalin A (ConA) was increased in human hepatic stellate cells (HSCs) following activation by transforming growth factor-β1 (TGF-β1); however, little is known about the ConA-binding glycoproteins (CBGs) of HSCs. In this study, we employed a targeted glycoproteomics approach using lectin-magnetic particle conjugate-based liquid chromatography-tandem mass spectrometry to compare CBG profiles between LX-2 HSCs with and without activation by TGF-β1, with the aim of discovering novel CBGs and determining their possible roles in activated HSCs. A total of 54 and 77 proteins were identified in the quiescent and activated LX-2 cells, respectively. Of the proteins identified, 14.3% were glycoproteins and 73.3% were novel potential glycoproteins. Molecules involved in protein processing in the endoplasmic reticulum (e.g., calreticulin) and calcium signaling (e.g., 1-phosphatidylinositol-4,5-bisphosphate phosphodiesterase β-2 [PLCB2]) were specifically identified in activated LX-2 cells. Additionally, PLCB2 expression was upregulated in the cytoplasm of the activated LX-2 cells, as well as in the hepatocytes and sinusoidal cells of liver cirrhosis tissues. In conclusion, the results of this study may aid future investigations to find new molecular mechanisms involved in HSC activation and antifibrotic therapeutic targets.

Current scenario for the hepatoprotective effects of Inchinkoto, a traditional herbal medicine, and its clinical application in liver surgery: A review

Inchinkoto (ICKT) is one of the most commonly used herbal medicines as a hepatoprotective agent. Among the numerous chemical compounds included in ICKT, geniposide is the most abundant component. Geniposide, after p.o. intake, is converted to the active metabolite genipin by intestinal bacteria and is absorbed in the portal circulation. The biological properties of ICKT and genipin have been studied in numerous experiments. Administration of ICKT or genipin exerts choleretic effects through upregulation of multidrug resistance-associated protein 2 in hepatocytes. ICKT also exerts an anti-apoptotic action through inhibition of transforming growth factor-β1- or tumor necrosis factor-α-dependent signaling pathways. The excessive inflammatory response induced by various hepatic stresses is also attenuated by ICKT pre-administration. Moreover, ICKT upregulates antioxidant enzymes in the liver under conditions of oxidative stress. These experimental results suggest potential benefit of ICKT in liver disease and particularly in hepatic surgery, which justify further well-designed controlled clinical study. To date, however, clinical data regarding the benefit of ICKT for liver surgery are rare. This review article summarized and discussed recent evidence relating to the hepatoprotective effects of ICKT in the field of basic and clinical science.

Mechanisms of action of acetaldehyde in the up-regulation of the human α2(I) collagen gene in hepatic stellate cells: key roles of Ski, SMAD3, SMAD4, and SMAD7

Alcohol-induced liver fibrosis and eventually cirrhosis is a leading cause of death. Acetaldehyde, the first metabolite of ethanol, up-regulates expression of the human α2(I) collagen gene (COL1A2). Early acetaldehyde-mediated effects involve phosphorylation and nuclear translocation of SMAD3/4-containing complexes that bind to COL1A2 promoter to induce fibrogenesis. We used human and mouse hepatic stellate cells to elucidate the mechanisms whereby acetaldehyde up-regulates COL1A2 by modulating the role of Ski and the expression of SMADs 3, 4, and 7. Acetaldehyde induced up-regulation of COL1A2 by 3.5-fold, with concomitant increases in the mRNA (threefold) and protein (4.2- and 3.5-fold) levels of SMAD3 and SMAD4, respectively. It also caused a 60% decrease in SMAD7 expression. Ski, a member of the Ski/Sno oncogene family, is colocalized in the nucleus with SMAD4. Acetaldehyde induces translocation of Ski and SMAD4 to the cytoplasm, where Ski undergoes proteasomal degradation, as confirmed by the ability of the proteasomal inhibitor lactacystin to blunt up-regulation of acetaldehyde-dependent COL1A2, but not of the nonspecific fibronectin gene (FN1). We conclude that acetaldehyde up-regulates COL1A2 by enhancing expression of the transactivators SMAD3 and SMAD4 while inhibiting the repressor SMAD7, along with promoting Ski translocation from the nucleus to cytoplasm. We speculate that drugs that prevent proteasomal degradation of repressors targeting COL1A2 may have antifibrogenic properties.

Chronic vitamin C insufficiency aggravated thioacetamide-induced liver fibrosis in gulo-knockout mice

Given the involvement of oxidative stress in liver-disease- or hepato-toxicant-induced hepatic damage and fibrosis, antioxidants are an effective preventive and therapeutic tool. The beneficial results of vitamin C, one of the physiological antioxidants, have been observed both in experimental animals and in humans. However, most of these studies have been concerned with supplementary vitamin C; the effects of under vitamin C insufficiency, which humans sometimes confront, have not been substantially investigated. In the present study, we established a vitamin C-insufficient animal model (half-to-normal serum vitamin C concentration) with gulo(-/-) mice that cannot synthesize vitamin C, and induced hepatotoxicity by means of thioacetamide (TAA) injections twice a week for 18 weeks. Additionally, we explored the direct effects of vitamin C both on immortalized human hepatic stellate LX-2 cells and on rat primary hepatic stellate cells. Vitamin C insufficiency resulted in a decreased survival rate and increased serum markers for hepatocyte damage, such as alanine aminotransferase and aspartate aminotransferase. Concomitantly, the levels of reactive oxygen species (ROS) and lipid peroxides in the liver were increased. Histological examinations of the vitamin C-insufficient liver revealed increases in collagen fiber deposition and activated-hepatic-stellate-cell number. Vitamin C, when directly applied to the LX-2 cells as well as the rat primary hepatic stellate cells, suppressed not only proliferation but hydrogen peroxide-induced collagen expression as well. In conclusion, vitamin C insufficiency exacerbated TAA-induced hepatotoxicity. These effects seem to be mainly from insufficient scavenging of ROS in the liver, and possibly in part, by directly affecting hepatic stellate cells.

Allopurinol reverses liver damage induced by chronic carbon tetrachloride treatment by decreasing oxidative stress, TGF-β production and NF-κB nuclear translocation

Allopurinol is an inhibitor of xanthine oxidase. The aim of this work was to evaluate the efficacy of allopurinol to reverse the experimental cirrhosis induced by CCl4. Rats received CCl4 for 8 weeks, and immediately after allopurinol was administered for 4 weeks more. Allopurinol reversed all markers of liver damage and oxidative stress to normal values, restoring the metabolic capacity of the liver. Chronic injury by CCl4 induced significant overexpression of profibrogenic cytokine TGF-β, while allopurinol decreased this production and consequently decreased the collagen content. Moreover, allopurinol is capable of partially inhibiting NF-κB. These findings suggest that allopurinol is capable of reversing the cirrhosis induced by CCl4, modulating oxidative stress, TGF-β expression and NF-κB nuclear translocation.

TGF-β1 up-regulates the expression of PDGF-β receptor mRNA and induces a delayed PI3K-, AKT-, and p70(S6K) -dependent proliferative response in activated hepatic stellate cells

BACKGROUND

Transforming growth factor beta 1 (TGF-β1) is a pleiotropic cytokine that activates hepatic stellate cell (HSC) proliferation, but inhibits parenchymal cell proliferation. Therefore, we hypothesize that TGF-β1 regulates HSC proliferation and elucidated its molecular action.

METHODS

In order to elucidate the molecular mechanism whereby TGF-β1 up-regulates platelet derived growth factor beta (PDGF-β) receptor mRNA and induces a delayed proliferation of HSC, we used proliferation and apoptosis assays as well as RT-PCR, Western blot analysis, immunostaining, and flow cytometry in mouse and rat HSC.

RESULTS

We show that TGF-β1 markedly induces the proliferation of mouse HSC in culture with concomitant 2.1-fold (p < 0.001) stimulation in [(3) H]-thymidine incorporation into cellular DNA. This induction is maximal between 24 and 36 hours postcytokine exposure that is triggered by 7.6-fold (p < 0.001) up-regulation of PDGF-β receptor mRNA and associated increase in PDGF-β receptor protein after 48 hours. TGF-β1-dependent HSC proliferation is mimicked by H2 O2 that is inhibited by catalase, implying that TGF-β1 action is mediated via reactive oxygen species. HSC proliferation is blunted by PDGF-β receptor-neutralizing antibody as well as by specific inhibitors of PI3 kinase (PI3K), AKT, and p70(S6K) , indicating that the action of TGF-β1 involves the activation of PDGF-β receptor via the PI3K/AKT/p70(S6K) signaling pathway. TGF-β1 also induces a reorganization of actin and myosin filaments and cell morphology leading to the formation of palisades although their myosin and actin contents remained constant. These findings suggest that TGF-β1-mediated oxidative stress causes the transdifferentiation of HSC and primes them for extracellular matrix (ECM) deposition and scar contraction.

CONCLUSIONS

We conclude that liver injury up-regulates TGF-β1 that inhibits parenchymal cell proliferation, but stimulates HSC proliferation leading to the production of ECM and type I collagen resulting in fibrosis.

Astragaloside IV suppresses collagen production of activated hepatic stellate cells via oxidative stress-mediated p38 MAPK pathway

Oxidative stress is involved in hepatic fibrogenesis. Activation of hepatic stellate cells (HSCs), the key effectors in hepatic fibrogenesis, is characterized by overproduction of extracellular matrix. Astragaloside IV, the active component of Radix Astragali, has antioxidant properties and antifibrotic potential in renal fibrosis. Little is known about the role of astragaloside IV in liver and its involvement in hepatic fibrosis. This study aims at evaluating the antifibrotic potential of astragaloside IV and characterizing involved signal transduction pathways in culture-activated HSCs. Our results show that astragaloside IV attenuates oxidative stress in culture-activated HSCs, as demonstrated by scavenging reactive oxygen species and reducing lipid peroxidation, and elevates the level of cellular glutathione by stimulating Nrf2gene expression. Depletion of cellular glutathione by buthionine sulfoximine or abrogation of p38 MAPK by SB-203580 evidently eliminates the inhibitory effects of astragaloside IV on genes relevant to HSC activation. These results demonstrate that astragaloside IV inhibits HSC activation by inhibiting generation of oxidative stress and associated p38 MAPK activation and provide novel insights into the mechanisms of astragaloside IV as an antifibrogenic candidate in the prevention and treatment of liver fibrosis.

Effect of bioactive peptide of Carapax Trionycis on TGF-β1-induced intracellular events in hepatic stellate cells

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicines for hepatic fibrosis therapy, Carapax Trionycis is used usually as an indispensable component and has a long history of medical use in China. Previous studies have demonstrated that extracts of Carapax Trionycis were able to protect liver against fibrosis in CCl4 animal models.

AIM OF THE STUDY

The purpose of this study is to verify the inhibitory effect and the underlying mechanisms of Carapax Trionycis extract peptide (CTEP) on activated hepatic stellate cells which play a central role in liver fibrogenesis.

MATERIALS AND METHODS

Hepatic stellate cells induced by TGF-β1 were applied to evaluate the anti-fibrotic effect of CTEP in vitro. MTS assay, enzyme-linked immunosorbent assay and western blotting were then used to further investigate the molecular mechanisms.

RESULTS

The results show that the contents of collagen I, collagen III and TIMP-1 were significantly inhibited and the level of collagen I, collagen III, p-Smad 3, TIMP-1 and α-SMA proteins decreased significantly in a concentration-dependence manner after treatment with CTEP. Interestingly, the level of Smad 3 protein was not different significantly.

CONCLUSIONS

Our data indicate that CTEP efficiently inhibits cultured HSC-T6 cell activation and proliferation via the TGF-β1/Smad pathway as well as by the elimination of the extracellular matrix.

Butyrate-producing probiotics reduce nonalcoholic fatty liver disease progression in rats: new insight into the probiotics for the gut-liver axis

Nonalcoholic fatty liver disease (NAFLD) includes simple steatosis, nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. The gut-derived endotoxin plays an essential role in the pathophysiological development and progression of NAFLD. By using rat models of choline-deficient/L-amino acid-defined (CDAA)-diet-induced NAFLD, we examined whether MIYAIRI 588–a butyrate-producing probiotic – prevents the progression of pathophysiological changes from steatosis to hepatocarcinogenesis. In vivo experiments showed that treatment with MIYAIRI 588 reduced CDAA-diet-induced hepatic lipid deposition and significantly improved the triglyceride content, insulin resistance, serum endotoxin levels, and hepatic inflammatory indexes. We also found that MIYAIRI 588 substantially increased the activation of hepatic adenosine 5′-monophosphate-activated protein kinase (AMPK) and AKT and the expression of lipogenesis- or lipolysis-related proteins. MIYAIRI 588 also improved CDAA-diet-induced delocalization and substantially decreased the expression of the tight-junction proteins intestinal zonula occluden-1 and occludin in CDAA-diet-fed rats. Further, the MIYAIRI 588-treated rats also showed remarkable induction of nuclear factor erythoid 2-related factor 2 (Nrf2) and its targeted antioxidative enzymes, which suppressed hepatic oxidative stress. In vitro studies revealed that treatment with sodium butyrate (NaB) also activated AMPK and AKT and enhanced Nrf2 expression by precluding ubiquitination, thereby increasing the half-life of the Nrf2 protein. Pharmacological studies and siRNA knockdown experiments showed that NaB-mediated AMPK activation induced the phosphorylation and nuclear translocation of Sirtuin 1, leading to the increased assembly of mammalian TOR complex 2 and phosphorylation of AKT at Ser473 and subsequent induction of Nrf2 expression and activation. These favorable changes caused an obvious decrease in hepatic fibrous deposition, GST-P-positive foci development, and hepatocarcinogenesis. Our data clearly established that the probiotic MIYAIRI 588 has beneficial effects in the prevention of NAFLD progression.

Peripheral type I interferon receptor correlated with oxidative stress in chronic hepatitis B virus infection

Type I interferon receptor (IFNAR) has been involved in the progression of chronic hepatitis B (CHB). Oxidative stress is also associated with hepatitis B virus (HBV) infection and might contribute to the structure and function of protein synthesis including the IFNAR family. This study was aimed to determine the possible associations between oxidative stress and peripheral IFNAR expression in chronic HBV infection. Fifty-four CHB patients and 31 liver cirrhosis (LC) patients were consecutively collected, as well as 11 healthy subjects as controls. Expression levels of IFNAR1 and IFNAR2 in peripheral blood lymphocytes and monocytes were measured by flow cytometry. IFNAR1 and IFNAR2c mRNA were detected by real-time reverse transcription-polymerase chain reaction. Levels of plasma-soluble IFNAR and oxidative stress parameters, including xanthine oxidase (XOD), malondialdehyde (MDA), glutathione (GSH), glutathione S-transferase (GST), and glutathione peroxidase (GSH-Px) were detected by enzyme linked immunosorbent assay (ELISA). The frequencies of IFNAR1 and IFNAR2 in lymphocytes and monocytes were significantly increased in CHB and LC patients than in healthy controls. Expression levels of IFNAR1 and IFNAR2c mRNA and plasma-soluble IFNAR level in CHB and LC patients were upregulated compared with healthy controls. Mean fluorescence intensity (MFI) of IFNAR2 in monocytes of CHB patients was higher than that in LC patients. Levels of plasma XOD, MDA, and GST were significantly increased in CHB and LC patients compared with healthy controls. Meanwhile, GSH and GSH-Px in CHB and LC patients were decreased than that in healthy controls. Furthermore, plasma MDA, GSH, and GST levels in CHB patients were higher than that in LC patients. In CHB patients, plasma GST level was negatively correlated with MFI of IFNAR2 in lymphocytes. Our results suggested that oxidative stress play an important role in the regulation of IFNAR in chronic HBV infection.

Nrf2 activators attenuate the progression of nonalcoholic steatohepatitis-related fibrosis in a dietary rat model

Oxidative stress is considered to be a key mechanism of hepatocellular injury and disease progression in patients with nonalcoholic steatohepatitis (NASH). The transcription factor Nrf2 (nuclear factor-erythroid-2-related factor 2) plays a central role in stimulating expression of various antioxidant-associated genes in the cellular defense against oxidative stress. As the cytosolic repressor kelch-like ECH-associated protein 1 (Keap1) negatively regulates Nrf2, activation of Nrf2 facilitated by its release from Keap1 may represent a promising strategy in the treatment of NASH. To test this hypothesis, we used two chemically distinct types of Nrf2 activator. One is the thiol-reactive agent oltipraz (OPZ), a typical Nrf2 activator, and the other is a novel biaryl urea compound, termed NK-252 (1-(5-(furan-2-yl)-1,3,4-oxadiazol-2-yl)-3-(pyridin-2-ylmethyl)urea). NK-252 exhibits a greater Nrf2-activating potential than OPZ. Furthermore, in vitro binding studies revealed that NK-252 interacts with the domain containing the Nrf2-binding site of Keap1, whereas OPZ does not. This finding indicates that NK-252 is more potent than OPZ due to its unique mechanism of action. For in vivo animal model studies, we used rats on a choline-deficient L-amino acid-defined (CDAA) diet, which demonstrate pathologic findings similar to those seen in human NASH. The administration of OPZ or NK-252 significantly attenuated the progression of histologic abnormalities in rats on a CDAA diet, especially hepatic fibrosis. In conclusion, by using Nrf2 activators with independent mechanisms of action, we show that, in a rat model of NASH, the activation of Nrf2 is responsible for the antifibrotic effects of these drugs. This strategy of Nrf2 activation presents new opportunities for treatment of NASH patients with hepatic fibrosis.