Smad2 protects against TGF-β1/Smad3-mediated collagen synthesis in human hepatic stellate cells during hepatic fibrosis

Histidine improves flesh quality: An assessment of grass carp (Ctenopharyngodon idella) muscle in terms of texture, nutritional value and flavor

The texture, nutritional value, and flavor quality of muscle significantly contribute to the flesh quality. To investigate the beneficial impacts of histidine on the flesh quality of grass carp (Ctenopharyngodon idella), a 63-day feeding trial was conducted using six diets containing histidine at concentrations of 1.08 (control diet), 2.91, 5.87, 8.83, 11.78, and 14.79 g/kg. The findings indicated that histidine mitigated the rapid decline in pH, potentially correlated with elevated carnosine and expression of H+ transporters. Notably, our study is the first to suggest that histidine supplementation may enhance fish flesh hardness by promoting collagen synthesis and inhibiting collagen degradation. Furthermore, histidine supplementation enhanced the nutritional and flavor quality of flesh by altering the fatty acid and free amino acid profiles. Based on pH24h (muscle pH at 24 h post-slaughter) and shear force, the dietary histidine requirements for adult grass carp were 8.09 and 8.44 g/kg, respectively.

Investigating the Antifibrotic Effects of β-Citronellol on a TGF-β1-Stimulated LX-2 Hepatic Stellate Cell Model

Liver fibrosis, a consequence of chronic liver damage or inflammation, is characterized by the excessive buildup of extracellular matrix components. This progressive condition significantly raises the risk of severe liver diseases like cirrhosis and hepatocellular carcinoma. The lack of approved therapeutics underscores the urgent need for novel anti-fibrotic drugs. Hepatic stellate cells (HSCs), key players in fibrogenesis, are promising targets for drug discovery. This study investigated the anti-fibrotic potential of Citrus hystrix DC. (KL) and its bioactive compound, β-citronellol (β-CIT), in a human HSC cell line (LX-2). Cells exposed to TGF-β1 to induce fibrogenesis were co-treated with crude KL extract and β-CIT. Gene expression was analyzed by real-time qRT-PCR to assess fibrosis-associated genes (ACTA2, COL1A1, TIMP1, SMAD2). The release of matrix metalloproteinase 9 (MMP-9) was measured by ELISA. Proteomic analysis and molecular docking identified potential signaling proteins and modeled protein-ligand interactions. The results showed that both crude KL extract and β-CIT suppressed HSC activation genes and MMP-9 levels. The MAPK signaling pathway emerged as a potential target of β-CIT. This study demonstrates the ability of KL extract and β-CIT to inhibit HSC activation during TGF-β1-induced fibrogenesis, suggesting a promising role of β-CIT in anti-hepatic fibrosis therapies.

Mairin from Huangqi Decoction Mitigates Liver Cirrhosis through Suppression of Pro-inflammatory Signaling Pathways: A Network Pharmacology and Experimental Study

Background::

Liver cirrhosis is a consequence of various chronic liver conditions and may lead to liver failure and cancer. Huangqi Decoction (HQD) is a Traditional Chinese Medicine (TCM) effective for treating liver conditions, including cirrhosis. Therefore, both the active ingredients and the pharmacological actions of HQD deserve further exploration. The active components and pharmacological actions of HQD in preventing and treating liver cirrhosis were investigated using network pharmacology. The actions of the principal active ingredient, Mairin, were investigated empirically.

Methods::

Using network pharmacology, the critical components of HQD were identified from multiple databases, and UPLC screening and targets were investigated using Swiss Target Prediction. Targets associated with liver cirrhosis were identified using the GeneCards database. GO and KEGG enrichment analysis of targets that overlapped between HQD and cirrhosis were analyzed in DAVID, and a “component-target-pathway” network for HQD was created in Cytoscape 3.7.2. The biological functions of the key active component, Mairin, were investigated using in silico docking, cell experiments, and evaluation in a carbon-tetrachloride (CCl4)-induced mouse model of liver cirrhosis. CCK-8 and F-actin assays were used to measure cell viability and hepatic stellate cell (HSC) activation, respectively; fibrosis was measured by histological and immunohistochemical evaluations, and the levels of the cirrhosis-related protein α-SMA and predicted essential target proteins in the PI3KAKT, NFκB-IκBα, and NLRP3-IL18 pathways were determined by western blotting.

Results::

Fourteen active HQD components, 72 targets, and 10 pathways common to HQD and cirrhosis were identified. Network analysis indicated the association of Mairin with most targets and with inflammation through the PI3K/Akt, NF-κB, and NLRP3 pathways. Dose-dependent reductions in the activation and proliferation of LX-2 cells after Mairin treatment were observed. Mairin reversed the histopathological changes in the livers of cirrhosis model mice. Mairin also significantly reduced the α-SMA, NF-κB, IκBα, NLRP3, and IL-18 protein levels while increasing those of p- PI3K and p-Akt, suggesting that Mairin mitigates liver cirrhosis through modulation of the PI3KAKT, NFκB-IκBα, and NLRP3-IL18 pathways.

Conclusions::

Using a comprehensive investigative process involving network pharmacology, bioinformatics, and experimental verification, it was found that Mairin, an active component of HQD, may be useful for developing specific treatments for preventing and treating liver cirrhosis.

The miR-3074/BMP7 axis regulates TGF-β-caused activation of hepatic stellate cells in vitro and CCl4-caused murine liver fibrosis in vivo

Continuously progressive hepatic fibrosis might cause chronic liver diseases, resulting in hepatic failure. The activation of hepatic stellate cells (HSCs) residing in the liver might induce and influence hepatic fibrosis. In the present study, microRNA 3074 (miR-3074) was found increased within transforming growth factor-β (TGF-β)-activated HSCs and enriched within the TGF-β signaling. In activated HSCs by TGF-β, miR-3074 overexpression aggravated TGF-β-induced fibrotic changes, whereas miR-3074 inhibition exerted opposite effects. miR-3074 directly targeted bone morphogenetic protein 7 (BMP7) and inhibited BMP7 expression. Under TGF-β induction, overexpressed BMP7 notably attenuated the promotive roles of miR-3074 overexpression in TGF-β-activated HSCs. Within carbon tetrachloride (CCl4)-caused liver fibrosis murine model, miR-3074 agomir administration promoted, while LV-BMP7 administration alleviated CCl4-induced fibrotic changes; LV-BMP7 significantly attenuated the effects of miR-3074 agomir. Lastly, mmu-miR-3074 also targeted mouse BMP7 and inhibited mouse BMP7 expression. In conclusion, the miR-3074/BMP7 axis regulates TGF-β-caused activation of HSCs in vitro and CCl4-caused murine liver fibrosis in vivo. BMP7-mediated Smad1/5/8 activation might be involved.

CLC-3 regulates TGF-β/smad signaling pathway to inhibit the process of fibrosis in hypertrophic scar

Objective

To study the role and mechanism of chloride channel-3 (ClC-3) in the formation of hypertrophic scar by constructing ClC-3 interference vectors and examining their effects on human hypertrophic scar fibroblasts (HSFB).

Methods

Human HSFB and human normal skin fibroblasts (NSFB) were used in this study, and ClC-3 interference vectors were constructed to transfect cells. ClC-3 inhibitors NPPB and Tamoxifen were used to treat cells. Cell migration and the expression of TGF-β/Smad, CollagenⅠ,CollagenⅢ were examined to explore the role of ClC-3 in the formation of hypertrophic scar.

Results

Compared with the normal skin tissue, the positive expression of ClC-3 and TGF-β in the scar tissue was significantly increased. The relative expression of ClC-3 and TGF-β1 in HSFB cells was higher than that in NSFB cells. Interfering with the expression of CLC-3 can inhibit the migration of HSFB cells and the expression of TGF- β/Smad, CollagenⅠ/Ⅲ. The experiment of HSFB cells treated by CLC-3 inhibitors can also obtain similar results.

Conclusion

Inhibiting CLC-3 can reduce the formation of hypertrophic scars.

Loss of Krüppel-like factor-10 facilitates the development of chemical-induced liver cancer in mice

BACKGROUND

Krüppel-like factor 10 (KLF10) is involved in a positive feedback loop that regulates transforming growth factor β (TGFβ) signaling, and TGFβ plays an important role in the pathogenesis of liver disease. Here, we investigated whether KLF10 deletion affects the development of liver fibrosis and hepatocellular carcinoma (HCC).

METHODS

We induced KLF10 deletion in C57BL/6 mice. Liver fibrosis was induced by feeding a diet high in fat and sucrose (high-fat diet [HFD]), whereas HCC was produced by intraperitoneal administration of N-diethylnitrosamine (DEN). An in vitro experiment was performed to evaluate the role of KLF10 in the cancer microenvironment using Hep3B and LX2 cells. An immunohistochemical study of KLF10 expression was performed using human HCC samples from 60 patients who had undergone liver resection.

RESULTS

KLF10 deletion resulted in an increased DEN-induced HCC burden with significant upregulation of SMAD2, although loss of KLF10 did not alter HFD-induced liver fibrosis. DEN-treated mice with KLF10 deletion exhibited increased levels of mesenchymal markers (N-cadherin and SNAI2) and tumor metastasis markers (matrix metalloproteinases 2 and 9). KLF10 depletion in Hep3B and LX2 cells using siRNA was associated with increased invasiveness. Compared with co-culture of KLF10-preserved Hep3B cells and KLF10-intact LX2 cells, co-culture of KLF10-preserved Hep3B cells and KLF10-depleted LX2 cells resulted in significantly enhanced invasion. Low KLF10 expression in resected human HCC specimens was associated with poor survival.

CONCLUSION

The results of this study suggest that loss of KLF10 facilitates liver cancer development with alteration in TGFβ signaling.

Hepatic stellate cell-intrinsic role of SOCS1 in controlling hepatic fibrogenic response and the pro-inflammatory macrophage compartment during liver fibrosis

Introduction

Hepatic stellate cells (HSC) become activated, differentiate to myofibroblasts and produce extracellular fibrillar matrix during liver fibrosis. The hepatic fibrogenic response is orchestrated by reciprocal interactions between HSCs and macrophages and their secreted products. SOCS1 can regulate several cytokines and growth factors implicated in liver fibrosis. Here we investigated the role of SOCS1 in regulating HSC activation.

Methods

Mice lacking SOCS1 in HSCs (Socs1ΔHSC) were generated by crossing Socs1fl/fl and LratCre mice. Liver fibrosis was induced by carbon tetrachloride and evaluated by Sirius red staining, hydroxyproline content and immunostaining of myofibroblasts. Gene expression of pro-fibrogenic factors, cytokines, growth factors and chemokines were quantified by RT-qPCR. The phenotype and the numbers of intrahepatic leukocyte subsets were studied by flow cytometry. The impact of fibrosis on the development of diethyl nitrosamine-induced hepatocellular carcinoma was evaluated.

Results

Socs1ΔHSC mice developed more severe liver fibrosis than control Socs1fl/fl mice that was characterized by increased collagen deposition and myofibroblast differentiation. Socs1ΔHSC mice showed a significant increase in the expression of smooth muscle actin, collagens, matrix metalloproteases, cytokines, growth factors and chemokines in the liver following fibrosis induction. The fibrotic livers of Socs1ΔHSC mice displayed heightened inflammatory cell infiltration with increased proportion and numbers of Ly6ChiCCR2+ pro-inflammatory macrophages. This macrophage population contained elevated numbers of CCR2+CX3CR1+ cells, suggesting impaired transition towards restorative macrophages. Fibrosis induction following exposure to diethyl nitrosamine resulted in more numerous and larger liver tumor nodules in Socs1ΔHSC mice than in Socs1fl/fl mice.

Discussion

Our findings indicate that (i) SOCS1 expression in HSCs is a critical to control liver fibrosis and development of hepatocaellular carcinoma, and (ii) attenuation of HSC activation by SOCS1 regulates pro-inflammatory macrophage recruitment and differentiation during liver fibrosis.

Therapeutic implications of targeting autophagy and TGF-β crosstalk for the treatment of liver fibrosis

Liver fibrosis is characterized by the excessive deposition and accumulation of extracellular matrix components, mainly collagens, and occurs in response to a broad spectrum of triggers with different etiologies. Under stress conditions, autophagy serves as a highly conserved homeostatic system for cell survival and is importantly involved in various biological processes. Transforming growth factor-β1 (TGF-β1) has emerged as a central cytokine in hepatic stellate cell (HSC) activation and is the main mediator of liver fibrosis. A growing body of evidence from preclinical and clinical studies suggests that TGF-β1 regulates autophagy, a process that affects various essential (patho)physiological aspects related to liver fibrosis. This review comprehensively highlights recent advances in our understanding of cellular and molecular mechanisms of autophagy, its regulation by TGF-β, and the implication of autophagy in the pathogenesis of progressive liver disorders. Moreover, we evaluated crosstalk between autophagy and TGF-β1 signalling and discussed whether simultaneous inhibition of these pathways could represent a novel approach to improve the efficacy of anti-fibrotic therapy in the treatment of liver fibrosis.

Extracellular matrix remodelling in obesity and metabolic disorders

Obesity causes extracellular matrix (ECM) remodelling which can develop into serious pathology and fibrosis, having metabolic effects in insulin-sensitive tissues. The ECM components may be increased in response to overnutrition. This review will focus on specific obesity-associated molecular and pathophysiological mechanisms of ECM remodelling and the impact of specific interactions on tissue metabolism. In obesity, complex network of signalling molecules such as cytokines and growth factors have been implicated in fibrosis. Increased ECM deposition contributes to the pathogenesis of insulin resistance at least in part through activation of cell surface integrin receptors and CD44 signalling cascades. These cell surface receptors transmit signals to the cell adhesome which orchestrates an intracellular response that adapts to the extracellular environment. Matrix proteins, glycoproteins, and polysaccharides interact through ligand-specific cell surface receptors that interact with the cytosolic adhesion proteins to elicit specific actions. Cell adhesion proteins may have catalytic activity or serve as scaffolds. The vast number of cell surface receptors and the complexity of the cell adhesome have made study of their roles challenging in health and disease. Further complicating the role of ECM-cell receptor interactions is the variation between cell types. This review will focus on recent insights gained from studies of two highly conserved, ubiquitously axes and how they contribute to insulin resistance and metabolic dysfunction in obesity. These are the collagen-integrin receptor-IPP (ILK-PINCH-Parvin) axis and the hyaluronan-CD44 interaction. We speculate that targeting ECM components or their receptor-mediated cell signalling may provide novel insights into the treatment of obesity-associated cardiometabolic complications.

Retinol-binding protein-hijacking nanopolyplex delivering siRNA to cytoplasm of hepatic stellate cell for liver fibrosis alleviation

Activated hepatic stellate cell (aHSC) is mainly responsible for deposition of extracellular collagen matrix that causes liver fibrosis. Although several siRNAs adequately inhibited HSC activation in vitro, they were demonstrated poor RNAi efficiency in vivo. Developing HSC-targeting and cytoplasmic delivery nanocarrier is highly essential to acquire a desirable siRNA therapeutic index for anti-liver fibrosis. Here, we developed a unique crosslinking nanopolyplex (called T-C-siRNA) modified by vitamin A (VA) with the well-designed natures, including the negative charge, retinol-binding protein (RBP) hijacking, and cytoplasmic siRNA release in response to ROS and cis diol molecules. The nanopolyplex was given a yolk-shell-like shape, camouflage ability in blood, and HSC-targeting capability by hijacking the endogenous ligand RBP via surface VA. PDGFR-β siRNA (siPDGFR-β) supplied via T-C-siPDGFR-β nanopolyplex dramatically reduced HSC activation and its production of pro-fibrogenic proteins in vitro and in vivo. Furthermore, T-C-siPDGFR-β nanopolyplex effectively alleviated CCl4-induced liver injury, decreased hepatic collagen sediment, and recovered liver function in mice. This study provides a sophisticated method for HSC-targeting cytoplasmic RNA delivery using endogenous ligand hijacking and dual sensitivity of ROS and cis diol compounds.

Krüppel-like factor 10 (KLF10) as a critical signaling mediator: Versatile functions in physiological and pathophysiological processes

Krüppel-like factor 10 (KLF10), also known as TGFβ-inducible early gene-1 (TIEG1), was first found in human osteoblasts. Early studies show that KLF10 plays an important role in osteogenic differentiation. Through decades of research, KLF10 has been found to have complex functions in many different cell types, and its expression and function is regulated in multiple ways. As a downstream factor of transforming growth factor β (TGFβ)/SMAD signaling, KLF10 is involved in various biological functions, including glucose and lipid metabolism in liver and adipose tissue, the maintenance of mitochondrial structure and function of the skeletal muscle, cell proliferation and apoptosis, and plays roles in multiple disease processes, such as nonalcoholic steatohepatitis (NASH) and tumor. Besides, KLF10 shows gender-dependent difference of regulation and function in many aspects. In this review, the biological functions of KLF10 and its roles in disease states is updated and discussed, which would provide new insights into the functional roles of KLF10 and a clearer view of potential therapeutic strategies by targeting KLF10.

Sulforaphane prevents and reverses allergic airways disease in mice via anti-inflammatory, antioxidant, and epigenetic mechanisms

Sulforaphane has been investigated in human pathologies and preclinical models of airway diseases. To provide further mechanistic insights, we explored L-sulforaphane (LSF) in the ovalbumin (OVA)-induced chronic allergic airways murine model, with key hallmarks of asthma. Histological analysis indicated that LSF prevented or reversed OVA-induced epithelial thickening, collagen deposition, goblet cell metaplasia, and inflammation. Well-known antioxidant and anti-inflammatory mechanisms contribute to the beneficial effects of LSF. Fourier transform infrared microspectroscopy revealed altered composition of macromolecules, following OVA sensitization, which were restored by LSF. RNA sequencing in human peripheral blood mononuclear cells highlighted the anti-inflammatory signature of LSF. Findings indicated that LSF may alter gene expression via an epigenetic mechanism which involves regulation of protein acetylation status. LSF resulted in histone and α-tubulin hyperacetylation in vivo, and cellular and enzymatic assays indicated decreased expression and modest histone deacetylase (HDAC) inhibition activity, in comparison with the well-known pan-HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). Molecular modeling confirmed interaction of LSF and LSF metabolites with the catalytic domain of metal-dependent HDAC enzymes. More generally, this study confirmed known mechanisms and identified potential epigenetic pathways accounting for the protective effects and provide support for the potential clinical utility of LSF in allergic airways disease.

The Role of Mesothelin in Activation of Portal Fibroblasts in Cholestatic Liver Injury

Fibrosis is a common consequence of abnormal wound healing, which is characterized by infiltration of myofibroblasts and formation of fibrous scar. In liver fibrosis, activated Hepatic Stellate Cells (aHSCs) and activated Portal Fibroblasts (aPFs) are the major contributors to the origin of hepatic myofibroblasts. aPFs are significantly involved in the pathogenesis of cholestatic fibrosis, suggesting that aPFs may be a primary target for anti-fibrotic therapy in cholestatic injury. aPFs are distinguishable from aHSCs by specific markers including mesothelin (Msln), Mucin 16 (Muc16), and Thymus cell antigen 1 (Thy1, CD90) as well as fibulin 2, elastin, Gremlin 1, ecto-ATPase nucleoside triphosphate diphosphohydrolase 2. Msln plays a critical role in activation of PFs, via formation of Msln-Muc16-Thy1 complex that regulates TGFβ1/TGFβRI-mediated fibrogenic signaling. The opposing pro- and anti-fibrogenic effects of Msln and Thy1 are key components of the TGFβ1-induced activation pathway in aPFs. In addition, aPFs and activated lung and kidney fibroblasts share similarities across different organs with expression of common markers and activation cascade including Msln-Thy1 interaction. Here, we summarize the potential function of Msln in activation of PFs and development of cholestatic fibrosis, offering a novel perspective for anti-fibrotic therapy targeting Msln.

Dietary protein levels changed the hardness of muscle by acting on muscle fiber growth and the metabolism of collagen in sub-adult grass carp (Ctenopharyngodon idella)

Background

Nutrient regulation has been proven to be an effective way to improve the flesh quality in fish. As a necessary nutrient for fish growth, protein accounts for the highest proportion in the fish diet and is expensive. Although our team found that the effect of protein on the muscle hardness of grass carp was probably related to an increased collagen content, the mechanism for this effect has not been deeply explored. Moreover, few studies have explored the protein requirements of sub-adult grass crap (Ctenopharyngodon idella). Therefore, the effects of different dietary protein levels on the growth performance, nutritional value, muscle hardness, muscle fiber growth, collagen metabolism and related molecule expression in grass carp were investigated.

Methods

A total of 450 healthy grass carp (721.16 ± 1.98 g) were selected and assigned randomly to six experimental groups with three replicates each (n = 25/replicate), and were fed six diets with 15.91%, 19.39%, 22.10%, 25.59%, 28.53% and 31.42% protein for 60 d.

Results

Appropriate levels of dietary protein increased the feed intake, percentage weight gain, specific growth rate, body composition, unsaturated fatty acid content in muscle, partial free amino acid content in muscle, and muscle hardness of grass carp. These protein levels also increased the muscle fiber density, the frequency of new muscle fibers, the contents of collagen and IGF-1, and the enzyme activities of prolyl 4-hydroxylases and lysyloxidase, and decreased the activity of matrix metalloproteinase-2. At the molecular level, the optimal dietary protein increased collagen type I α1 (Colα1), Colα2, PI3K, Akt, S6K1, La ribonucleoprotein domain family member 6a (LARP6a), TGF-β1, Smad2, Smad4, Smad3, tissue inhibitor of metalloproteinase-2, MyoD, Myf5, MyoG and MyHC relative mRNA levels. The levels of the myostatin-1 and myostatin-2 genes were downregulated, and the protein expression levels of p-Smad2, Smad2, Smad4, p-Akt, Akt, LARP6 and Smad3 were increased.

Conclusions

The appropriate levels of dietary protein promoted the growth of sub-adult grass carp and improved muscle hardness by promoting the growth of muscle fibers, improving collagen synthesis and depressing collagen degradation. In addition, the dietary protein requirements of sub-adult grass carp were 26.21% and 24.85% according to the quadratic regression analysis of growth performance (SGR) and the muscle hardness (collagen content), respectively.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00747-7.

Gasotransmitters: Potential Therapeutic Molecules of Fibrotic Diseases

Fibrosis is defined as the pathological progress of excessive extracellular matrix (ECM), such as collagen, fibronectin, and elastin deposition, as the regenerative capacity of cells cannot satisfy the dynamic repair of chronic damage. The well-known features of tissue fibrosis are characterized as the presence of excessive activated and proliferated fibroblasts and the differentiation of fibroblasts into myofibroblasts, and epithelial cells undergo the epithelial-mesenchymal transition (EMT) to expand the number of fibroblasts and myofibroblasts thereby driving fibrogenesis. In terms of mechanism, during the process of fibrosis, the activations of the TGF-β signaling pathway, oxidative stress, cellular senescence, and inflammatory response play crucial roles in the activation and proliferation of fibroblasts to generate ECM. The deaths due to severe fibrosis account for almost half of the total deaths from various diseases, and few treatment strategies are available for the prevention of fibrosis as yet. Recently, numerous studies demonstrated that three well-defined bioactive gasotransmitters, including nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), generally exhibited anti-inflammatory, antioxidative, antiapoptotic, and antiproliferative properties. Besides these effects, a number of studies have reported that low-dose exogenous and endogenous gasotransmitters can delay and interfere with the occurrence and development of fibrotic diseases, including myocardial fibrosis, idiopathic pulmonary fibrosis, liver fibrosis, renal fibrosis, diabetic diaphragm fibrosis, and peritoneal fibrosis. Furthermore, in animal and clinical experiments, the inhalation of low-dose exogenous gas and intraperitoneal injection of gaseous donors, such as SNAP, CINOD, CORM, SAC, and NaHS, showed a significant therapeutic effect on the inhibition of fibrosis through modulating the TGF-β signaling pathway, attenuating oxidative stress and inflammatory response, and delaying the cellular senescence, while promoting the process of autophagy. In this review, we first demonstrate and summarize the therapeutic effects of gasotransmitters on diverse fibrotic diseases and highlight their molecular mechanisms in the process and development of fibrosis.

Pathophysiological communication between hepatocytes and non-parenchymal cells in liver injury from NAFLD to liver fibrosis

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial disease that encompasses a spectrum of pathological conditions, ranging from simple steatosis (NAFL), nonalcoholic steatohepatitis (NASH), fibrosis/cirrhosis which can further progress to hepatocellular carcinoma and liver failure. The progression of NAFL to NASH and liver fibrosis is closely associated with a series of liver injury resulting from lipotoxicity, oxidative stress, redox imbalance (excessive nitric oxide), ER stress, inflammation and apoptosis that occur sequentially in different liver cells which ultimately leads to the activation of liver regeneration and fibrogenesis, augmenting collagen and extracellular matrix deposition and promoting liver fibrosis and cirrhosis. Type 2 diabetes is a significant risk factor in NAFLD development by accelerating liver damage. Here, we overview recent findings from human study and animal models on the pathophysiological communication among hepatocytes (HCs), Kupffer cells (KCs), hepatic stellate cells (HSCs) and liver sinusoidal endothelial cells (LSECs) during the disease development. The mechanisms of crucial signaling pathways, including Toll-like receptor, TGFβ and hedgehog mediated hepatic injury are also discussed. We further highlight the potentials of precisely targeting hepatic individual cell-type using nanotechnology as therapeutic strategy for the treatment of NASH and liver fibrosis.

Antifibrotic Effects of Kangxian Ruangan Capsule on Rats with Nonalcoholic Fatty Liver Fibrosis and Hepatic Stellate Cells through Regulation of TGF-β and TLR4 Signaling Pathways

Kangxian ruangan (KXRG) is a traditional Chinese medicine (TCM) formula consisting of 12 herbs. TCM syndrome differentiation proposes that KXRG exerts pharmacological effects against nonalcoholic fatty liver disease (NAFLD) fibrosis. This work investigates the effect of KXRG on NAFLD fibrosis in vivo and in vitro. In vivo, the NAFLD fibrosis model was constructed in Wistar rats using methionine- and choline-deficient (MCD) diet, followed by KXRG (0.92 g/kg/d) treatment for 8 weeks. In vitro, primary hepatic stellate cells (HSCs) were activated using platelet-derived growth factor (PDGF) and treated with KXRG. Molecular mechanisms underlying fibrosis were investigated. After 8 weeks, compared with the control groups, the histological lesions, degree of fibrosis, and inflammatory reaction increased with the MCD diet as demonstrated by histological changes and increased fibrosis-related (α-SMA, TGF-β, COL1A1, and desmin, P < 0.01) and inflammation-related factors (TNF-α, MCP-1, and F4/80, P < 0.01), whereas they decreased with KXRG treatment (P < 0.01). KXRG not only inhibited the proliferation of activated HSCs and promoted their apoptosis but also resulted in G0-G1 arrest. Furthermore, KXRG suppressed HSC activation (P < 0.01), collagen synthesis (P < 0.01), and α-SMA expression (P < 0.01) with PDGF stimulation. In both the MCD diet-induced animal model and PDGF-induced cell model, KXRG inhibited TGF-β and TLR4 signaling (P < 0.01), similar to corresponding small-molecule inhibitors. These results demonstrated that KXRG might exert suppressive effects against NAFLD fibrosis via regulating TGF-β and TLR4 signaling. KXRG may act as a natural and potent therapeutic agent against NAFLD.

Repairing of Subchondral Defect and Articular Cartilage of Knee Joint of Rabbit by Gadolinium Containing Bio-Nanocomposites

A variety of gadolinium (Gd) based nanoparticles (NPs) were synthesized due to the unique magnetic properties of Gd-containing rare earth compounds and the particularity of micro/nano-materials, which were then incorporated into hydroxyapatite (HA) to obtain inorganic-organic composite materials. Then, HA/Gd NPs containing slow-release transforming growth factor (TGF-β1) were harvested. Adipose-derived stem cells (ADSCs) were extracted from the adipose tissue of a four-month-old New Zealand white rabbit. HA/Gd NPs were attached to absorbable gelatin sponge to obtain HA/Gd NPs/gelatin sponge composite scaffold. In addition, the third generation ADSCs were taken and cultured in the composite scaffold, so that ADSCs-HA/Gd bio-nanocomposites were obtained. The in vitro culture test of osteoblast MC3T3-E1 showed that Gd-containing NPs had good biocompatibility. The prepared HA/Gd NPs loaded with TGF-β1 were spherical, with an average particle size of (9.16 ± 3.16) μm. The NPs were easy to aggregate and adherent. Enzyme-linked immunosorbent assay (ELISA) test results showed that TGF-β1 in NPs was sustained and released continuously for 29 days. HA/Gd NPs/gelatin sponge composite scaffold combined with ADSCs were co-cultured for three days, and the electron microscope showed that the HA/Gd NPs were dispersed, and the cells could adhere and grow well. Then, animal models of rabbit knee articular cartilage defects were established and were rolled into three groups (ADSCs-HA/Gd nano group, HA/Gd nano scaffold group, and blank control). The repair area of the rabbit knee of ADSCs-HA/Gd nano group was smooth and flat, the scaffold was absorbed, the toluidine blue stain was positive, and the type II collagen immunohistochemical stain was positive. In general, ADSCs-HA/Gd nanomaterials were helpful for chondrogenic cell differentiation and had certain adoption prospects in the field of tissue engineering to repair cartilage defects.

Mesenchymal Stem Cells Therapies on Fibrotic Heart Diseases

Stem cell therapy is a promising alternative approach to heart diseases. The most prevalent source of multipotent stem cells, usually called somatic or adult stem cells (mesenchymal stromal/stem cells, MSCs) used in clinical trials is bone marrow (BM-MSCs), adipose tissue (AT-MSCs), umbilical cord (UC-MSCs) and placenta. Therapeutic use of MSCs in cardiovascular diseases is based on the benefits in reducing cardiac fibrosis and inflammation that compose the cardiac remodeling responsible for the maintenance of normal function, something which may end up causing progressive and irreversible dysfunction. Many factors lead to cardiac fibrosis and failure, and an effective therapy is lacking to reverse or attenuate this condition. Different approaches have been shown to be promising in surpassing the poor survival of transplanted cells in cardiac tissue to provide cardioprotection and prevent cardiac remodeling. This review includes the description of pre-clinical and clinical investigation of the therapeutic potential of MSCs in improving ventricular dysfunction consequent to diverse cardiac diseases.

Adipocyte Fatty Acid Binding Protein Promotes the Onset and Progression of Liver Fibrosis via Mediating the Crosstalk between Liver Sinusoidal Endothelial Cells and Hepatic Stellate Cells

Development of liver fibrosis results in drastic changes in the liver microenvironment, which in turn accelerates disease progression. Although the pathological function of various hepatic cells in fibrogenesis is identified, the crosstalk between them remains obscure. The present study demonstrates that hepatic expression of adipocyte fatty acid binding protein (A-FABP) is induced especially in the liver sinusoidal endothelial cells (LSECs) in mice after bile duct ligation (BDL). Genetic ablation and pharmacological inhibition of A-FABP attenuate BDL- or carbon tetrachloride-induced liver fibrosis in mice associating with reduced collagen accumulation, LSEC capillarization, and hepatic stellate cell (HSC) activation. Mechanistically, elevated A-FABP promotes LSEC capillarization by activating Hedgehog signaling, thus impairs the gatekeeper function of LSEC on HSC activation. LSEC-derived A-FABP also acts on HSCs in paracrine manner to potentiate the transactivation of transforming growth factor β1 (TGFβ1) by activating c-Jun N-terminal kinase (JNK)/c-Jun signaling. Elevated TGFβ1 subsequently exaggerates liver fibrosis. These findings uncover a novel pathological mechanism of liver fibrosis in which LSEC-derived A-FABP is a key regulator modulating the onset and progression of the disease. Targeting A-FABP may represent a potential approach against liver fibrosis.

Deletion of KLF10 Leads to Stress-Induced Liver Fibrosis upon High Sucrose Feeding

Liver fibrosis is a consequence of chronic liver injury associated with chronic viral infection, alcohol abuse, and nonalcoholic fatty liver. The evidence from clinical and animal studies indicates that transforming growth factor-β (TGF-β) signaling is associated with the development of liver fibrosis. Krüppel-like factor 10 (KLF10) is a transcription factor that plays a significant role in TGF-β-mediated cell growth, apoptosis, and differentiation. In recent studies, it has been reported to be associated with glucose homeostasis and insulin resistance. In the present study, we investigated the role of KLF10 in the progression of liver disease upon a high-sucrose diet (HSD) in mice. Wild type (WT) and Klf10 knockout (KO) mice were fed either a control chow diet or HSD (50% sucrose) for eight weeks. Klf10 KO mice exhibited significant hepatic steatosis, inflammation, and liver injury upon HSD feeding, whereas the WT mice exhibited mild hepatic steatosis with no apparent liver injury. The livers of HSD-fed Klf10 KO mice demonstrated significantly increased endoplasmic reticulum stress, oxidative stress, and proinflammatory cytokines. Klf10 deletion led to the development of sucrose-induced hepatocyte cell death both in vivo and in vitro. Moreover, it significantly increased fibrogenic gene expression and collagen accumulation in the liver. Increased liver fibrosis was accompanied by increased phosphorylation and nuclear localization of Smad3. Here, we demonstrate that HSD-fed mice develop a severe liver injury in the absence of KLF10 due to the hyperactivation of the endoplasmic reticulum stress response and CCAAT/enhance-binding protein homologous protein (CHOP)-mediated apoptosis of hepatocytes. The current study suggests that KLF10 plays a protective role against the progression of hepatic steatosis into liver fibrosis in a lipogenic state.

Quercetin regulates fibrogenic responses of endometrial stromal cell by upregulating miR-145 and inhibiting the TGF-β1/Smad2/Smad3 pathway

OBJECTIVES

Aim of this study is to explore whether quercetin can inhibit the enlarged fibrogenic responses of endometrial stromal cells by increasing the level of microRNA-145 (miR-145) and mediating the TGFβ1/Smad2/Smad3 signaling pathway, and to discuss the mechanism of signal transduction, further to provide experimental basis for revealing the pathophysiological mechanism and seeking new strategies for effective prevention and treatment of endometrial fibrosis.

METHODS

The expression levels of miR-145 and TGF-β receptor 2 (TGFBR2) were detected by RT-qPCR analysis. Expressions of α-smooth muscle actin (α-SMA) and vimentin were examined by immunofluorescence staining. Cell viability was measured by MTT assay. The protein expression of collagen type 1 alpha 1 (Col1a1), α-SMA, fibronectin (FN), TGFBR2, transforming growth factor (TGF-β1), Smad2/3, phospho-Smad2/3 (p-Smad2/3) were detected by western blot analysis. The interaction between miR-145 and TGFBR2 was confirmed by dual-luciferase reporter gene assay.

RESULTS

The expression level of miR-145 was decreased, whereas TGFBR2 was increased in intrauterine adhesion tissue. The expression levels of COL1A1, α-SMA, FN, TGFBR2, and p-Smad2/3 were increased, whereas miR-145 and cell proliferation were decreased in human endometrial stromal cells (hESCs) in response to TGF-β1 stimulation in a time and dose-dependent manner, which could be reversed by quercetin. Furthermore, quercetin regulates cell fibrogenic responses of endometrial stromal cells via miR-145/TGF-β1/Smad2/Smad3 pathway.

CONCLUSIONS

These findings indicated that quercetin have a significant anti-fibrotic effect and could upregulate miR-145 and inhibit activation of TGF-β1/Smad2/Smad3 pathway to regulate TGF-β1 induced fibrogenic responses of endometrial stromal cells, which may serve as a potential therapeutic agent for endometrial fibrosis.

Astragaloside IV Synergizes with Ferulic Acid to Alleviate Hepatic Fibrosis in Bile Duct-Ligated Cirrhotic Rats

BACKGROUND

Due to the multi-factorial etiology of hepatic fibrosis, multi-target therapeutics based on combinatory drugs is known to be a promising strategy for the disease.

AIMS

The present study attempted to test the hypothesis that astragaloside IV combined with ferulic acid synergistically inhibits activation of hepatic stellate cells in vivo.

METHODS

Bile duct-ligated rats were treated with astragaloside IV or/and ferulic acid for 28 days. Liver fibrosis was measured by histological examination. The oxidative stress-related biomarkers were measured with spectrophotometry. Expressions of mRNA and protein were measured by real-time PCR and Western blotting.

RESULTS

Bile duct-ligated rat treatment with astragaloside IV and ferulic acid in combination resulted in synergistic alleviation of hepatic fibrosis. Simultaneously, activation of hepatic stellate cells was significantly inhibited by the combination therapy when compared with astragaloside IV or ferulic acid alone. Interestingly, astragaloside IV, but not ferulic acid, induced accumulation of Nrf2 in the nucleus, synthesized antioxidant enzymes through negative regulation of glycogen synthase kinase-3β, scavenged reactive oxygen species, and, in turn, suppressed hepatic stellate cells activation in bile duct-ligated rats. Conversely, ferulic acid, but not astragaloside IV, suppressed TGF-β1 and its receptors expression, which resulted in downregulation of Smad3 and Smad4.

CONCLUSIONS

These findings suggest that the combination of astragaloside IV and ferulic acid synergistically induces deactivation of hepatic stellate cells through inhibition of the TGF-β pathway and activation of the Nrf2 pathway, and suggest that combination of astragaloside IV and ferulic acid is a promising candidate for the treatment of hepatic fibrosis.

Activation of Nrf2/AREs-mediated antioxidant signalling, and suppression of profibrotic TGF-β1/Smad3 pathway: a promising therapeutic strategy for hepatic fibrosis - A review

Hepatic fibrosis (HF) is a wound-healing response that occurs during chronic liver injury and features by an excessive accumulation of extracellular matrix (ECM) components. Activation of hepatic stellate cell (HSC), the leading effector in HF, is responsible for overproduction of ECM. It has been documented that transforming growth factor-β1 (TGF-β1) stimulates superfluous accumulation of ECM and triggers HSCs activation mainly via canonical Smad-dependent pathway. Also, the pro-fibrogenic TGF-β1 is correlated with generation of reactive oxygen species (ROS) and inhibition of antioxidant mechanisms. Moreover, involvement of oxidative stress (OS) can be clearly elucidated as a fundamental event in liver fibrogenesis. Nuclear factor erythroid 2-related factor 2-antioxidant response elements (Nrf2-AREs) pathway, a group of OS-mediated transcription factors with diverse downstream targets, is associated with the induction of diverse detoxifying enzymes and the most pivotal endogenous antioxidative system. More specifically, Nrf2-AREs pathway has recently assigned as a new therapeutic target for cure of HF. The overall goal of this review will focus on recent findings about activation of Nrf2-AREs-mediated antioxidant and suppression of profibrotic TGF-β1/Smad3 pathway in the liver, providing an overview of recent advances in transcriptional repressors that dislocated during HF formation, and highlighting possible novel therapeutic targets for liver fibrosis.

Single-Step, High-Efficiency CRISPR-Cas9 Genome Editing in Primary Human Disease-Derived Fibroblasts

Genome editing is a tool that has many applications, including the validation of potential drug targets. However, performing genome editing in low-passage primary human cells with the greatest physiological relevance is notoriously difficult. High editing efficiency is desired because it enables gene knockouts (KO) to be generated in bulk cellular populations and circumvents the problem of having to generate clonal cell isolates. Here, we describe a single-step workflow enabling >90% KO generation in primary human lung fibroblasts via CRISPR ribonucleoprotein delivery in the absence of antibiotic selection or clonal expansion. As proof of concept, we edited two SMAD family members and demonstrated that in response to transforming growth factor beta, SMAD3, but not SMAD2, is critical for deposition of type I collagen in the fibrotic response. The optimization of this workflow can be readily transferred to other primary cell types.

Anti-fibrotic activity of gold and platinum complexes - Au(I) compounds as a new class of anti-fibrotic agents

Molecular gold(I) and platinum(II) species were examined for the inhibition of liver fibrosis and the hepatitis C virus (HCV). Determination of inhibition efficiency was conducted via morphological analysis, cell viability, western blot analysis, and quantitative reverse transcription polymerase chain reaction (RT-PCR). Auranofin and Ph₃PAuCl demonstrated the greatest inhibition of liver fibrosis amongst the tested gold species in human hepatic stellate LX-2 cells. Western blot analysis indicated that auranofin and Ph₃PAuCl prevent signal transducer and activator of transcription 3 (STAT3) phosphorylation, which may be a key connection to fibrosis and inflammation. Auranofin and Ph₃PAuCl also reduced expression of HCV-nonstructural protein 3 (NS3) and HCV-NS5a proteins in a HCV subgenomic replicon system. These results demonstrate significant promise for the use of gold compounds in treating liver diseases such as HCV.

Smad2 and Smad3 play antagonistic roles in high glucose-induced renal tubular fibrosis via the regulation of SnoN

Diabetic nephropathy (DN) is a serious microvascular complication of diabetes mellitus.The main pathological features of DN include glomerular sclerosis and renal tubular interstitial fibrosis, which results in epithelial mesenchymal transition (EMT) and excessive extracellular matrix (ECM) deposition.Transforming growth factor-β1(TGF-β1) is a critical factor that regulates the manifestation of renal fibrosis.Smad2 and Smad3 are the main downstream of the TGF-β1 pathway. Ski-related novel protein N(SnoN) is a negative regulator of TGF-β1, and inhibits the activation of the TGF-β1/Smad2/3 signalling pathway. In this study, the expression of Smad2 and Smad3 proteins, SnoN mRNA, SnoN proteins, and the ubiquitination levels of SnoN were determined in DN rats and renal tubular epithelial cells(NRK52E cells). Knockdown and overexpression of Smad2 or Smad3 in NRK52E cells were used to investigate the specific roles of Smad2 and Smad3 in the development of high glucose-induced renal tubular fibrosis, with a specific focus on their effect on the regulation of SnoN expression. Our study demonstrated that Smad3 could inhibit SnoN expression and increase ECM deposition in NRK52E cells, to promote high glucose-induced renal tubular fibrosis. In contrast, Smad2 could induce SnoN expression and reduce ECM deposition, to inhibit high glucose-induced fibrosis. The underlying mechanism involves regulation of SnoN expression. These findings provide a novel mechanism to understanding the significant role of the TGF-β1/ Smad2/3 pathway in DN.

TIM-4 interference in Kupffer cells against CCL4-induced liver fibrosis by mediating Akt1/Mitophagy signalling pathway

OBJECTIVES

T-cell immunoglobulin domain and mucin domain-4 (TIM-4) is selectively expressed on antigen-presenting cells (APCs) and modulates various immune responses. However, the role of TIM-4 expressed by Kupffer cells (KCs) in liver fibrosis remains unclear. The present study aimed to explore whether and how TIM-4 expressed by KCs is involved in liver fibrosis.

MATERIALS AND METHODS

Mice chronic liver fibrosis models were established and divided into the olive-induced control group, CCL4-induced control group, olive-induced TIM-4 interference group and CCL4-induced TIM-4 interference group. Different techniques were used to monitor the fibrotic effects of TIM-4, including histopathological assays, Western blotting, ELISA and transmission electron microscopy. Additionally, mice liver transplant models were established to determine the fibrotic effects of TIM-4 on fibrosis after liver transplantation (LT).

RESULTS

We found that the induction of liver fibrosis by CCL4 was associated with TIM-4 expression in KCs. TIM-4 interference essentially contributed to liver fibrosis resolution. KCs from the TIM-4 interference group had decreased levels of pro-fibrotic markers, reduced TGF-β1 secretion and inhibited hepatic stellate cell (HSC) differentiation into myofibroblast-like cells. In addition, we used GdCl3 to verify that KCs are the primary source of TGF-β1 during fibrosis progression. Moreover, KCs from CCL4-induced mice showed increased ROS production, mitophagy activation and TGF-β1 secretion. However, TIM-4 interference in the KCs inhibited Akt1-mediated ROS production, resulting in the suppression of PINK1, Parkin and LC3-II/I activation and the reduction of TGF-β1 secretion during liver fibrosis. Additionally, TIM-4 interference potentially attenuated development of fibrosis after LT.

CONCLUSIONS

Our findings revealed the underlying mechanisms of TIM-4 interference in KCs to mitigate liver fibrosis.

Multi-technique comparison of atherogenic and MCD NASH models highlights changes in sphingolipid metabolism

Lipotoxicity is a key player in the pathogenesis of nonalcoholic steatohepatitis (NASH), a progressive subtype of nonalcoholic fatty liver disease (NAFLD). In the present study, we combine histological, transcriptional and lipidomic approaches to dissociate common and specific alterations induced by two classical dietary NASH models (atherogenic (ATH) and methionine/choline deficient (MCD) diet) in C57BL/6J male mice. Despite a similar degree of steatosis, MCD-fed mice showed more pronounced liver damage and a worsened pro-inflammatory and pro-fibrogenic environment than ATH-fed mice. Regarding lipid metabolism, the ATH diet triggered hepatic counter regulatory mechanisms, while the MCD diet worsened liver lipid accumulation by a concomitant increase in lipid import and reduction in lipid export. Liver lipidomics revealed sphingolipid enrichment in both NASH models that was accompanied by an upregulation of the ceramide biosynthesis pathway and a significant rise in dihydroceramide levels. In contrast, the phospholipid composition was not substantially altered by the ATH diet, whereas the livers of MCD-fed mice presented a reduced phosphatidylcholine to phosphatidylethanolamine (PC/PE) ratio and a strong depletion in phospholipids containing the sum of 34-36 carbons in their fatty acid chains. Therefore, the assessment of liver damage at the histological and transcriptional level combined with a lipidomic analysis reveals sphingolipids as shared mediators in liver lipotoxicity and pathogenesis of NASH.

Epigenetic SMAD3 Repression in Tumor-Associated Fibroblasts Impairs Fibrosis and Response to the Antifibrotic Drug Nintedanib in Lung Squamous Cell Carcinoma

The tumor-promoting fibrotic stroma rich in tumor-associated fibroblasts (TAF) is drawing increased therapeutic attention. Intriguingly, a trial with the antifibrotic drug nintedanib in non-small cell lung cancer reported clinical benefits in adenocarcinoma (ADC) but not squamous cell carcinoma (SCC), even though the stroma is fibrotic in both histotypes. Likewise, we reported that nintedanib inhibited the tumor-promoting fibrotic phenotype of TAFs selectively in ADC. Here we show that tumor fibrosis is actually higher in ADC-TAFs than SCC-TAFs in vitro and patient samples. Mechanistically, the reduced fibrosis and nintedanib response of SCC-TAFs was associated with increased promoter methylation of the profibrotic TGFβ transcription factor SMAD3 compared with ADC-TAFs, which elicited a compensatory increase in TGFβ1/SMAD2 activation. Consistently, forcing global DNA demethylation of SCC-TAFs with 5-AZA rescued TGFβ1/SMAD3 activation, whereas genetic downregulation of SMAD3 in ADC-TAFs and control fibroblasts increased TGFβ1/SMAD2 activation, and reduced their fibrotic phenotype and antitumor responses to nintedanib in vitro and in vivo. Our results also support that smoking and/or the anatomic location of SCC in the proximal airways, which are more exposed to cigarette smoke particles, may prime SCC-TAFs to stronger SMAD3 epigenetic repression, because cigarette smoke condensate selectively increased SMAD3 promoter methylation. Our results unveil that the histotype-specific regulation of tumor fibrosis in lung cancer is mediated through differential SMAD3 promoter methylation in TAFs and provide new mechanistic insights on the selective poor response of SCC-TAFs to nintedanib. Moreover, our findings support that patients with ADC may be more responsive to antifibrotic drugs targeting their stromal TGFβ1/SMAD3 activation. SIGNIFICANCE: This study implicates the selective epigenetic repression of SMAD3 in SCC-TAFs in the clinical failure of nintedanib in SCC and supports that patients with ADC may benefit from antifibrotic drugs targeting stromal TGFβ1/SMAD3.

CAPN2 acts as an indicator of hepatitis B virus to induce hepatic fibrosis

This study is aimed to investigate whether calpain 2 (CAPN2) serves as an indicator of the hepatitis B virus (HBV) to induce hepatic fibrosis. Differentially-expressed genes (DEGs) in HBV-induced hepatic fibrosis and normal liver tissues were analyzed, and signal pathway which was analyzed by the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis using DEGs. Next, the gene-related network map was constructed using the Search Tool for the Retrieval of Interacting Genes. Moreover, CAPN2 protein expression, level of hepatic fibrosis, CAPN2 messenger RNA level, and protein levels of CAPN2, a-SAM, COL3A1, COL1A1, and MAPK1 were determined using Immunohistochemistry (IHC), hematoxylin and eosin, RT-qPCR, and western blot (WB), respectively. There were 420 DEGs screened in HBV-induced hepatic fibrosis and normal liver tissues, among which, 373 were significantly upregulated and 47 were obviously downregulated. KEGG analysis showed that the upregulated DEGs were mainly concentrated in extracellular matrix-receptor interaction, protein digestion, and absorption signaling pathways. The network diagram analysis showed that the DEGs, such as CAPN2, ITGAV, and CCR2, play the key role in the DEG network map, and CAPN2 related to hepatic fibrosis via MAPK1. The increased CAPN2 expression and obvious hepatic fibrosis was displayed in the HBV-induced hepatic fibrosis tissues. In addition, HBV could induce CAPN2 expression, and the interference of CAPN2 could inhibit the expression of hepatic fibrosis markers, including a-SAM, COL3A1, COL1A1, and MAPK1. CAPN2 is regarded as a biomarker of hepatic fibrosis induced by HBV.

The polysaccharides from Grifola frondosa attenuate CCl4-induced hepatic fibrosis in rats via the TGF-β/Smad signaling pathway

The TGF-β1/Smad signaling pathway has been linked to hepatic fibrosis. Previous studies have shown that yellow polysaccharide can prevent the development of hepatic fibrosis. However, it is unclear whether the polysaccharide affects the TGF-β1/Smad signaling pathway. In this experiment, 50 experimental rats were randomly divided into a normal control group, model group, low GFP dose group (50 mg kg^-1), medium GFP dose group (100 mg kg^-1), and high GFP dose group (200 mg kg^-1). A cirrhotic portal hypertension rat model was established by a CCl₄ compound method. After 12 weeks of intragastric administration, the liver index of the medium dose and high dose group was significantly lower than that of the model group. The hepatic fibrosis lesions of rats in each dose group were improved to different extents, and the effect was most significant in the high dose group. The contents of ALT, AST, TBIL and CIV, PCIII, LN and HA in serum were significantly decreased. The activity of SOD and GSH-Px in the liver tissue of GFP medium and high dose groups was significantly increased and the content of MDA was significantly decreased. The contents of TNF-α, IL-1β and IL-6 were significantly decreased. The western blot results showed that the expressions of p-Smad 2/3, Smad4, PAI-1, Imp7 and Imp8 in medium dose and high dose groups were significantly lower than those in the model group, while the expression of Smad7 was significantly higher than that of the model group. The GFP-treated group was able to reduce the expression level of mi R-154 in liver tissue and increase the expression level of miR-146a. GFP has a significant intervention effect on rat hepatic fibrosis, and its mechanism may inhibit the progression of hepatic fibrosis by inhibiting oxidative stress and inflammatory response and regulating TGF-β1/Smad signaling pathway and mi RNA expression.

Research progress on the anti-hepatic fibrosis action and mechanism of natural products

Hepatic fibrosis is the most common pathological feature of most chronic liver diseases, and its continuous deterioration gradually develops into liver cirrhosis and eventually leads to liver cancer. At present, there are many kinds of drugs used to treat liver fibrosis. However, Western drugs tend to only target single genes/proteins and induce many adverse reactions. Most of the mechanisms and active ingredients of traditional Chinese medicine (TCM) are not clear, and there is a lack of unified diagnosis and treatment standards. Natural products, which are characterized by structural diversity, low toxicity, and origination from a wide range of sources, have unique advantages and great potential in anti-liver fibrosis. This article summarizes the work done over the previous decade, on the active ingredients in natural products that are reported to have anti-hepatic fibrosis effects. The effective anti-hepatic fibrosis ingredients identified can be generally divided into flavonoids, saponins, polysaccharides and alkaloids. Mechanisms of anti-liver fibrosis include inhibition of liver inflammation, anti-lipid peroxidation injury, inhibition of the activation and proliferation of hepatic stellate cells (HSCs), modulation of the synthesis and secretion of pro-fibrosis factors, and regulation of the synthesis and degradation of the extracellular matrix (ECM). This review provides suggestions for the development of anti-hepatic fibrosis drugs.

Quercetin suppresses glomerulosclerosis and TGF‑β signaling in a rat model

The transforming growth factor-β (TGF-β) signaling pathway is an important regulatory pathway in renal fibrosis and is abnormally activated in glomerulosclerosis. Quercetin is a common Chinese herbal medicine and has been reported to inhibit TGF-β signaling pathway activation. In the present study a glomerulosclerosis rat model was constructed and mice were treated with different concentrations of quercetin. Biochemical parameters, pathological indices and expression levels of TGF-β signaling pathway-associated proteins were detected using immunohistochemistry and western blotting. It was demonstrated that quercetin significantly improved physiological indices and altered the expression levels of TGF-β signaling pathway-associated proteins in rats with glomerulosclerosis. In conclusion, quercetin can regulate the TGF-β signaling pathway and reduce the progression of glomerulosclerosis.

Cav-1 deficiency promotes liver fibrosis in carbon tetrachloride (CCl4)-induced mice by regulation of oxidative stress and inflammation responses

Caveolin-1 (Cav-1), as a membrane protein involved in the formation of caveolae, binds steroid receptors and endothelial nitric oxide synthase, limiting its translocation and activation. In the present study, we investigated the role of Cav-1 in the progression of hepatic fibrosis induced by carbon tetrachloride (CCl₄) in murine animals. Therefore, the wild type (WT) and Cav-1-knockout (Cav-1^-/-) mice were used in our study and subjected to CCl₄. The results indicated that CCl₄ induced the decrease of Cav-1 expression in liver tissue samples. And Cav-1^-/- intensified CCl₄-triggered hepatic injury, evidenced by the stronger hepatic histological alterations, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and liver terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells. CCl₄ led to oxidative stress, supported by the reduced superoxide dismutase (SOD) activity and glutathione (GSH) levels, as well as enhanced malondialdehyde (MDA) and O₂^- levels in liver samples. And the process was intensified by Cav-1^-/-. Additionally, CCl₄-caused hepatic inflammation was aggregated by Cav-1^-/- via further increasing the secretion of pro-inflammatory cytokines. Moreover, CCl₄-caused fibrosis was strengthened by Cav-1^-/-, which was evidenced by the up-regulation of α-smooth muscle actin (α-SMA), collagen alpha 1 type 1 (Col1A1), lysyl oxidase (Lox) and transforming growth factor-β1 (TGF-β1) in liver tissues. Similar results were observed in TGF-β1-stimulated hepatic stellate cells (HSCs) and LX-2 cells without Cav-1 expressions that in vitro, suppressing Cav-1 further accelerated TGF-β1-induced oxidative stress, inflammation and fibrosis development. In conclusion, our results indicated that Cav-1 played an important role in CCl₄-induced hepatic injury, which may be used as potential therapeutic target for hepatic fibrosis treatment.

Novel Insights on Notch signaling pathways in liver fibrosis

Liver fibrosis is characterized by an increased and altered deposition of extracellular matrix (ECM) proteins that make up excessive tissue scarring and promote chronic liver injury. Activation of hepatic stellate cells (HSCs) is a pivotal cellular event in the progression of liver fibrosis. However, the mechanisms involved in the development of liver fibrosis are only now beginning to be unveiled. The Notch pathway is a fundamental and highly conserved pathway able to control cell-fate, including cell proliferation, differentiation, apoptosis, regeneration and other cellular activities. Recently, the deregulation of Notch cascade has been found involved in many pathological processes, including liver fibrosis. These data give evidence for a role for Notch signaling in liver fibrosis. In addition，more and more date are available on the role of Notch pathways in the process. Therefore, this review focuses on the current knowledge about the Notch signaling pathway, which dramatically takes part in HSC activation and liver fibrosis, and look ahead on new perspectives of Notch signaling pathway research. Furthermore, we will summarize this new evidence on the different interactions in Notch signaling pathway-regulated liver fibrosis, and support the potentiality of putative biomarkers and unique therapeutic targets.

SENP1 attenuates the liver fibrosis through down-regulating the expression of SMAD2

To investigate whether SENP1 could play a regulating role in the liver fibrosis process, the Sprague-Dawley (SD) rats were used to establish the liver fibrosis rat models by intraperitoneally injecting with 1 ml/kg of 10% CCl₄, while the control normal rats were injected with olive oil. Then confirmation experiments to verify the successful establishment of these models were conducted by detecting the cellular and lobular architecture, and liver function indexes using hematoxylin-eosin staining, Masson's trichrome staining and microplate method, respectively. In addition, the expression levels of fibrosis markers including collagen I, collagen III, α-SMA and TGF-β1 were inspected using quantitative real-time PCR (qRT-PCR), as well as SMAD2. Subsequently, the relative mRNA and protein level of SENP1 was also determined via qRT-PCR and western blot analysis. Next, the HSC-T6 cells of SENP1 knock-down were constructed and used to test the relative protein expression levels of α-SMA and SMAD2 in these cells. The results of hematoxylin-eosin staining, Masson's trichrome staining and microplate method turned out that the rat liver fibrosis models were constructed successfully, which was further confirmed by the increased expression of collagen I, collagen III, α-SMA and TGF-β1 in mRNA and protein level, as well as SMAD2. Then the expression of SENP1 was overexpressed in the rat liver fibrosis models induced by CCl₄ and the TGF-β1 treatment could increase the protein expression level of collagen I, collagen III and α-SMA. Lastly, the SENP1 knockdown HSC-T6 cells were successfully constructed, while the silence of SENP1 down-regulated the protein expression of α-SMA and SMAD2. In conclusion, this study provided a new regulation mechanism about the liver fibrosis process.

Fibroblast-specific TGF-β-Smad2/3 signaling underlies cardiac fibrosis

The master cytokine TGF-β mediates tissue fibrosis associated with inflammation and tissue injury. TGF-β induces fibroblast activation and differentiation into myofibroblasts that secrete extracellular matrix proteins. Canonical TGF-β signaling mobilizes Smad2 and Smad3 transcription factors that control fibrosis by promoting gene expression. However, the importance of TGF-β-Smad2/3 signaling in fibroblast-mediated cardiac fibrosis has not been directly evaluated in vivo. Here, we examined pressure overload-induced cardiac fibrosis in fibroblast- and myofibroblast-specific inducible Cre-expressing mouse lines with selective deletion of the TGF-β receptors Tgfbr1/2, Smad2, or Smad3. Fibroblast-specific deletion of Tgfbr1/2 or Smad3, but not Smad2, markedly reduced the pressure overload-induced fibrotic response as well as fibrosis mediated by a heart-specific, latency-resistant TGF-β mutant transgene. Interestingly, cardiac fibroblast-specific deletion of Tgfbr1/2, but not Smad2/3, attenuated the cardiac hypertrophic response to pressure overload stimulation. Mechanistically, loss of Smad2/3 from tissue-resident fibroblasts attenuated injury-induced cellular expansion within the heart and the expression of fibrosis-mediating genes. Deletion of Smad2/3 or Tgfbr1/2 from cardiac fibroblasts similarly inhibited the gene program for fibrosis and extracellular matrix remodeling, although deletion of Tgfbr1/2 uniquely altered expression of an array of regulatory genes involved in cardiomyocyte homeostasis and disease compensation. These findings implicate TGF-β-Smad2/3 signaling in activated tissue-resident cardiac fibroblasts as principal mediators of the fibrotic response.

Knockdown of Fstl1 attenuates hepatic stellate cell activation through the TGF‑β1/Smad3 signaling pathway

Follistatin‑like 1 (Fstl1) is a secreted glycoprotein that belongs to the follistatin and SPARC (secreted protein, acidic and rich in cysteine) families and was identified to serve a critical role in lung fibrosis. However, the role of Fstl1 in liver fibrosis remains undefined. Therefore, the aim of the present study was to investigate the role of Fstl1 in liver fibrosis. The results indicated that Fstl1 was highly expressed in human hepatic fibrosis tissues and activated hepatic stellate cells (HSCs). Furthermore, knockdown of Fstl1effectively suppressed HSC proliferation and the protein expression levels of α‑SMA and collagen I in transforming growth factor (TGF)‑β1‑treated HSCs. Mechanistically, knockdown of Fstl1 remarkably decreased the phosphorylation level of Smad3 in TGF‑β1‑induced HSCs. Taken together, the present study demonstrated that Fstl1serves an important role in liver fibrosis and target deletion of Fstl1 attenuated HSCs activation through suppressing TGF‑β1/Smad3 signaling pathway. Therefore, Fstl1 may be a potential therapeutic target for the treatment of liver fibrosis.

TGF-β1 induces Fstl1 via the Smad3-c-Jun pathway in lung fibroblasts

Transforming growth factor (TGF)-β1 has long been regarded as a central mediator of tissue fibrosis. Follistatin-like 1 (Fstl1) is a crucial profibrotic glycoprotein that is upregulated in fibrotic lung tissues, and it promotes fibrogenesis via facilitating TGF-β signaling. Here we examined the signaling pathway by which TGF-β1 upregulates Fstl1 expression in mouse pulmonary fibroblasts. TGF-β1 regulated Fstl1 expression at both the transcriptional and translational levels. Although TGF-β1 rapidly activated the Smad, MAPK, and Akt pathways in lung fibroblasts, only Smad2/3 inhibition eliminated TGF-β1-induced Fstl1 expression. Analysis of the luciferase reporter activity identified a functional c-Jun transcription site in the Fstl1 promoter. Our results suggested a critical role for the Smad3-c-Jun pathway in the regulation of Fstl1 expression by TGF-β1 during fibrogenesis.

Nickel oxide nanoparticles induced pulmonary fibrosis via TGF-β1 activation in rats

Nano nickel oxide (NiO), widely used in industry, has recently been discovered to have pulmonary toxicity. However, no subchronic exposure studies about nano NiO-induced pulmonary fibrosis have been reported. The objective of this study was to investigate pulmonary fibrosis induced by nano NiO and its potential mechanism in rats. Male Wistar rats ( n = 40, 200–240 g) were randomized into control group, nano NiO groups (0.015, 0.06, and 0.24 mg/kg), and micro NiO group (0.024 mg/kg). All rats were killed to collect lung tissue after intratracheal instillation of NiO particles twice a week for 6 weeks. To identify pulmonary fibrosis, Masson trichrome staining, hydroxyproline content, and collagen protein expression were performed. The results showed widespread lung fibrotic injury in histological examination and increased content of hydroxyproline, collagen types I and III in rat lung tissue exposed to nano NiO. To explore the potential pulmonary fibrosis mechanism, transforming growth factor beta 1 (TGF- β1) content was measured by enzyme-linked immunosorbent assay, and the messenger RNA expression of key indicators was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The TGF- β1 content was increased in nano NiO exposure groups, as well as the upregulated gene expression of TGF- β1, Smad2, Smad4, matrix metalloproteinase, and tissue inhibitor of metalloproteinase. The findings indicated that nano NiO could induce pulmonary fibrosis, which may be related to TGF- β1 activation.

Smad2 overexpression enhances adhesion of gingival epithelial cells

OBJECTIVE

Gingival epithelial cells play an important role in preventing the initiation of periodontitis, by their hemidesmosomal adhesion to the tooth root surface. Adhesion requires integrin-extracellular matrix (ECM) interactions that are intricately regulated by transforming growth factor-β (TGF-β) signaling. However, the mechanisms underlying the interplay between adhesion molecules and TGF-β, especially the respective roles of Smad2 and Smad3, remain elusive. In this study, we examined the effects of Smad overexpression on gingival epithelial cell adhesion and expression profiles of integrin and ECM-related genes.

METHODS

Human gingival epithelial cells immortalized by the SV40 T-antigen were transfected with Smad2- and Smad3-overexpression vectors. A cell adhesion assay involving fluorescence detection of attached cells was performed using the ArrayScan imaging system. Real-time PCR was performed to examine the kinetics of integrin and ECM gene expression. In vitro and in vivo localization of adhesion molecules was examined by immunofluorescence analysis.

RESULTS

By using SB431542, a specific inhibitor of the TGF-β type I receptor, Smad2/3 signaling was confirmed to be dominant in TGF-β1-induced cell adhesion. The Smad2-transfectant demonstrated higher potency for cell adhesion and integrin expression (α2, α5, β4, and β6) than the Smad3-transfectant, whereas little or no change in ECM expression was observed in either transfectant. Moreover, the gingival epithelium of transgenic mice that overexpressed Smad2 driven by the keratin 14 promoter showed increased integrin α2 expression.

CONCLUSION

These findings indicate the crucial role of Smad2 in increased adhesion of gingival epithelial cells via upregulation of integrin α2.

Unfolded protein response induced by Brefeldin A increases collagen type I levels in hepatic stellate cells through an IRE1α, p38 MAPK and Smad-dependent pathway

Unfolded protein response (UPR) triggered as a consequence of ER stress has been shown to be involved in the development of different pathologies, including fibrotic disorders. In the present paper we explore the role played by UPR on a key fibrogenic parameter in the liver: collagen type I levels in activated hepatic stellate cells (HSC). Using Brefeldin A (BFA) as an ER stress inducer we found that UPR correlated with enhanced mRNA and protein levels of collagen type I in a cell line of immortalized non-tumoral rat HSC. Analysis of the three branches of UPR revealed the activation of IRE1α, PERK and ATF6 in response to BFA, although PERK activation was shown not to be involved in the fibrogenic action of BFA. BFA also activated p38 MAPK in an IRE1α-dependent way and the p38 MAPK inhibitor SB203580 prevented the increase in collagen type I mRNA and protein levels caused by BFA, suggesting the involvement of this kinase on this effect. Analysis of Smad activation showed that phosphorylated nuclear levels of Smad2 and 3 were increased in response to BFA treatment. Inhibition of Smad3 phosphorylation by SIS3 prevented the enhancement of collagen type I levels caused by BFA. Pretreatment with IRE1α and p38 MAPK inhibitors also prevented the increased p-Smad3 accumulation in the nucleus, suggesting an IRE1α-p38 MAPK-Smad pathway to be responsible for the fibrogenic action of BFA on HSC.

Smad2 increases the apoptosis of activated human hepatic stellate cells induced by TRAIL

The activation of hepatic stellate cells (HSCs) plays a critical role in the development of liver fibrosis. The induction of apoptosis in activated HSCs during the recovery phase of hepatic fibrosis represents a potential anti-fibrotic therapy. We have previously shown that Smad2 protects against hepatic fibrogenesis; however, the role of Smad2 in the regulation of activated HSC apoptosis remains unknown. We hypothesized that Smad2 regulates the apoptosis of activated HSCs, leading to the resolution of liver fibrosis. To test this hypothesis, the livers of rats were harvested at 0 and 4 weeks after hepatic fibrosis was established by CCl4 injection. Furthermore, TGF-β1-activated HSCs were treated with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) following the silencing or overexpression of Smad2. Both the phosphorylation of Smad2 and TRAIL were detected in fibrotic liver tissues. The results of TUNEL and α-SMA double-staining showed an increase in the apoptosis of activated HSCs during the spontaneous recovery phase. The knockdown of Smad2 reduced TRAIL-induced apoptosis in TGF-β1-activated human LX-2 cells and resulted in an increased expression of α-SMA and collagen I (Col. I). In contrast, the overexpression of Smad2 increased TRAIL-induced HSC apoptosis and reduced the expression of α-SMA and Col. I. The mechanisms underlying these findings were associated with the Smad2-mediated down-regulation of X-linked inhibitor of apoptosis protein (XIAP), resulting in enhanced caspase-3 activity and apoptosis. In conclusion, Smad2 enhances TRAIL-induced apoptosis in activated HSCs, which facilitates the resolution of hepatic fibrosis.

TGF-β/SMAD Pathway and Its Regulation in Hepatic Fibrosis

Transforming growth factor-beta1 (TGF-β1), a key member in the TGF-β superfamily, plays a critical role in the development of hepatic fibrosis. Its expression is consistently elevated in affected organs, which correlates with increased extracellular matrix deposition. SMAD proteins have been studied extensively as pivotal intracellular effectors of TGF-β1, acting as transcription factors. In the context of hepatic fibrosis, SMAD3 and SMAD4 are pro-fibrotic, whereas SMAD2 and SMAD7 are protective. Deletion of SMAD3 inhibits type I collagen expression and blocks epithelial-myofibroblast transition. In contrast, disruption of SMAD2 upregulates type I collagen expression. SMAD4 plays an essential role in fibrosis disease by enhancing SMAD3 responsive promoter activity, whereas SMAD7 negatively mediates SMAD3-induced fibrogenesis. Accumulating evidence suggests that divergent miRNAs participate in the liver fibrotic process, which partially regulates members of the TGF-β/SMAD signaling pathway. In this review, we focus on the TGF-β/SMAD and other relative signaling pathways, and discussed the role and molecular mechanisms of TGF-β/SMAD in the pathogenesis of hepatic fibrosis. Moreover, we address the possibility of novel therapeutic approaches to hepatic fibrosis by targeting to TGF-β/SMAD signaling.