Gene expression profile of quiescent and activated rat hepatic stellate cells implicates Wnt signaling pathway in activation

Polysaccharides of Atractylodes macrocephala Koidz alleviate bursa of Fabricius involution in Magang geese by inhibiting the Wnt signaling pathway

Involution of the bursa of Fabricius (BF) with increasing age in avian species leads to decreases in lymphocyte counts and pathogen recognition, thereby compromising immune function and increasing susceptibility to infections. Polysaccharides of Atractylodes macrocephala Koidz (PAMK), a major component of the traditional Chinese medicine Atractylodes macrocephala, increase immunity. This study aimed to explore the impact of PAMK on the BF during involution in Magang geese. Following the prefeeding period, 54 four-month-old Magang geese were selected for the experiment. These geese were evenly divided into three groups. Each group consisted of three replicates, with six geese per replicate. One group was immediately euthanized to collect serum and BF samples. The remaining 36 geese were further divided into two groups: one group was maintained on a standard diet, and the other group was provided a diet supplemented with 400 mg/kg PAMK. One month later, serum and BF samples were collected for analysis. Morphological, organ index and histological observations indicate that PAMK can alleviate the significant reduction in the organ index of the BF during the involution process in Magang geese and mitigate the disorder of follicular arrangement and the decrease in the ratio of the cortical area to the medullary area in the BF. Immunoglobulin and oxidative stress results revealed that PAMK can increase the levels of immunoglobulins and reduce oxidative stress in involuting Magang geese. Functional enrichment analysis revealed that the Wnt signaling pathway plays a significant role in alleviating the involution of the BF in Magang geese. Further cellular studies revealed that the addition of PAMK inhibited apoptosis and promoted cell cycle progression into the S and G2 phases. In summary, PAMK effectively mitigates the involution of the BF in Magang geese by inhibiting the Wnt signaling pathway, thereby enhancing humoral immunity and improving antioxidant status.

Cellular Crosstalk Promotes Hepatic Progenitor Cell Proliferation and Stellate Cell Activation in 3D Co-culture

BACKGROUND & AIMS

Following liver damage, ductular reaction often coincides with liver fibrosis. Proliferation of hepatic progenitor cells is observed in ductular reaction, whereas activated hepatic stellate cells (HSCs) are the main drivers of liver fibrosis. These observations may suggest a functional interaction between these 2 cell types. Here, we report on an in vitro co-culture system to examine these interactions and validate their co-expression in human liver explants.

METHODS

In a 3D organoid co-culture system, we combined freshly isolated quiescent mouse HSCs and fluorescently labeled progenitor cells (undifferentiated intrahepatic cholangiocyte organoids), permitting real-time observation of cell morphology and behavior. After 7 days, cells were sorted based on the fluorescent label and analyzed for changes in gene expression.

RESULTS

In the 3D co-culture system, the proliferation of progenitor cells is enhanced, and HSCs are activated, recapitulating the cellular events observed in the patient liver. Both effects in 3D co-culture require close contact between the 2 different cell types. HSC activation during 3D co-culture differs from quiescent (3D mono-cultured) HSCs and activated HSCs on plastic (2D mono-culture). Upregulation of a cluster of genes containing Aldh1a2, Cthrc1, and several genes related to frizzled binding/Wnt signaling were exclusively observed in 3D co-cultured HSCs. The localized co-expression of specific genes was confirmed by spatial transcriptomics in human liver explants.

CONCLUSION

An in vitro 3D co-culture system provides evidence for direct interactions between HSCs and progenitor cells, which are sufficient to drive responses that are similar to those seen during ductular reaction and fibrosis. This model paves the way for further research into the cellular basis of liver pathology.

System analysis based on weighted gene co-expression analysis identifies SOX7 as a novel regulator of hepatic stellate cell activation and liver fibrosis

Hepatic stellate cell (HSC) activation is the essential pathological process of liver fibrosis (LF). The molecular mechanisms regulating HSC activation and LF are incompletely understood. Here, we explored the effect of transcription factor SRY-related high mobility group box 7 (SOX7) on HSC activation and LF, and the underlying molecular mechanism. We found the expression levels of SOX7 were decreased in human and mouse fibrotic livers, particularly at the fibrotic foci. SOX7 was also downregulated in primary activated HSCs and TGF-β1 stimulated LX-2 cells. SOX7 knockdown promoted activation and proliferation of LX-2 cells while inhibiting their apoptosis. On the other hand, overexpression of SOX7 suppressed the activation and proliferation of HSCs. Mechanistically, SOX7 attenuates HSC activation and LF by decreasing the expression of β-catenin and phosphorylation of Smad2 and Smad3 induced by TGF-β1. Furthermore, overexpression of SOX7 using AAV8-SOX7 mouse models ameliorated the extent of LF in response to CCl4 treatment in vivo. Collectively, SOX7 suppressed HSC activation and LF. Targeting SOX7, therefore, could be a potential novel strategy to protect against LF.

Phillygenin Inhibits TGF-β1-induced Hepatic Stellate Cell Activation and Inflammation: Regulation of the Bax/Bcl-2 and Wnt/β-catenin Pathways

Hepatic fibrosis (HF), a precursor to cirrhosis and hepatocellular carcinoma, is caused by abnormal proliferation of connective tissue and excessive accumulation of extracellular matrix in the liver. Notably, activation of hepatic stellate cells (HSCs) is a key link in the development of HF. Phillygenin (PHI, C21H24O6) is a lignan component extracted from the traditional Chinese medicine Forsythiae Fructus, which has various pharmacological activities such as anti-inflammatory, antioxidant and anti-tumour effects. However, whether PHI can directly inhibit HSC activation and ameliorate the mechanism of action of HF has not been fully elucidated. Therefore, the aim of the present study was to investigate the in vitro anti-HF effects of PHI and the underlying molecular mechanisms. Transforming growth factor-β1 (TGF-β1)-activated mouse HSCs (mHSCs) and human HSCs (LX-2 cells) were used as an in vitro model of HF and treated with different concentrations of PHI for 24 h. Subsequently, cell morphological changes were observed under the microscope, cell viability was analyzed by MTT assay, cell cycle and apoptosis were detected by flow cytometry, and the mechanism of anti-fibrotic effect of PHI was explored by immunofluorescence, ELISA, RT-qPCR and western blot. The results showed that PHI suppressed the proliferation of TGF-β1-activated mHSCs and LX-2 cells, arrested the cell cycle at the G0/G1 phase, decreased the levels of α-SMA, Collagen I, TIMP1 and MMP2 genes and proteins, and promoted apoptosis in activated mHSCs and LX-2 cells. Besides, PHI reduced the expression of inflammatory factors in activated mHSCs and LX-2 cells, suggesting a potential anti-inflammatory effect. Mechanically, PHI inhibited TGF-β1-induced HSC activation and inflammation, at least in part through modulation of the Bax/Bcl-2 and Wnt/β-catenin pathways. Overall, PHI has significant anti-HF effects and may be a promising agent for the treatment of HF.

Cryo-electron microscopy for GPCR research and drug discovery in endocrinology and metabolism

G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors, with many GPCRs having crucial roles in endocrinology and metabolism. Cryogenic electron microscopy (cryo-EM) has revolutionized the field of structural biology, particularly regarding GPCRs, over the past decade. Since the first pair of GPCR structures resolved by cryo-EM were published in 2017, the number of GPCR structures resolved by cryo-EM has surpassed the number resolved by X-ray crystallography by 30%, reaching >650, and the number has doubled every ~0.63 years for the past 6 years. At this pace, it is predicted that the structure of 90% of all human GPCRs will be completed within the next 5-7 years. This Review highlights the general structural features and principles that guide GPCR ligand recognition, receptor activation, G protein coupling, arrestin recruitment and regulation by GPCR kinases. The Review also highlights the diversity of GPCR allosteric binding sites and how allosteric ligands could dictate biased signalling that is selective for a G protein pathway or an arrestin pathway. Finally, the authors use the examples of glycoprotein hormone receptors and glucagon-like peptide 1 receptor to illustrate the effect of cryo-EM on understanding GPCR biology in endocrinology and metabolism, as well as on GPCR-related endocrine diseases and drug discovery.

Microplastics cause hepatotoxicity in diabetic mice by disrupting glucolipid metabolism via PP2A/AMPK/HNF4A and promoting fibrosis via the Wnt/β-catenin pathway

In recent years, microplastics (MPs) have gained significant attention as a persistent environmental pollutant resulting from the decomposition of plastics, leading to their accumulation in the human body. The liver, particularly of individuals with type 2 diabetes mellitus (T2DM), is known to be more susceptible to the adverse effects of environmental pollutants. Therefore, to investigate the potential impact of MPs on the liver of diabetic mice and elucidate the underlying toxicological mechanisms, we exposed db/db mice to 0.5 μm MPs for 3 months. Our results revealed that MPs exposure resulted in several harmful effects, including decreased body weight, disruption of liver structure and function, elevated blood glucose levels, impaired glucose tolerance, and increased glycogen accumulation in the hepatic tissue of the mice. Furthermore, MPs exposure was found to promote hepatic gluconeogenesis by perturbing the PP2A/AMPK/HNF4A signaling pathway. In addition, MPs disrupt redox balance, leading to oxidative damage in the liver. This exposure also disrupted hepatic lipid metabolism, stimulating lipid synthesis while inhibiting catabolism, ultimately resulting in the development of fatty liver. Moreover, MPs were found to induce liver fibrosis by activating the Wnt/β-catenin signaling pathway. Furthermore, MPs influenced adaptive thermogenesis in brown fat by modulating the expression of uncoupling protein 1 (UCP1) and genes associated with mitochondrial oxidative respiration thermogenesis in brown fat. In conclusion, our study demonstrates that MPs induce oxidative damage in the liver, disturb glucose and lipid metabolism, promote hepatic fibrosis, and influence adaptive thermogenesis in brown fat in diabetic mice. These findings underscore the potential adverse effects of MPs on liver health in individuals with T2DM and highlight the importance of further research in this area.

MicroRNAs in infectious diseases: potential diagnostic biomarkers and therapeutic targets

MicroRNAs (miRNAs) are conserved, short, non-coding RNAs that play a crucial role in the post-transcriptional regulation of gene expression. They have been implicated in the pathogenesis of cancer and neurological, cardiovascular, and autoimmune diseases. Several recent studies have suggested that miRNAs are key players in regulating the differentiation, maturation, and activation of immune cells, thereby influencing the host immune response to infection. The resultant upregulation or downregulation of miRNAs from infection influences the protein expression of genes responsible for the immune response and can determine the risk of disease progression. Recently, miRNAs have been explored as diagnostic biomarkers and therapeutic targets in various infectious diseases. This review summarizes our current understanding of the role of miRNAs during viral, fungal, bacterial, and parasitic infections from a clinical perspective, including critical functional mechanisms and implications for their potential use as biomarkers and therapeutic targets.

Liposomal IL-22 ameliorates liver fibrosis through miR-let7a/STAT3 signaling in mice

The therapeutic effect of liposomal IL-22 versus non-liposomal IL-22 on liver fibrosis was investigated. IL-22 (5 µg/ml) was incorporated into negative charged liposomes. Schistosoma mansoni infected mice were treated with liposomal IL-22 for either 7 or 14 days before decapitation. Liver and spleen were removed and splenocytes were isolated for in vitro investigations. TNF-α, IL-17, IL-22 and IgE levels were assessed. Hepatic granulomas were counted, granuloma index and its developmental stages were calculated. Hepatic expressions of STAT3, β-catenin and let-7a miRNA were evaluated. Liposomal IL-22 size was clustered around 425.9 ± 58.0 nm with negative zeta potential (-18.8 ± 1.3 mV). After 14 days, 65.5% of IL-22 was released from liposomal IL-22 as was gradually observed in vitro. Liposomal IL-22 significantly (p < 0.05) decreased IL-17 level (-33.1%) of healthy splenocytes compared to non-liposomal IL-22. In vivo therapeutic effect of liposomal IL-22 revealed a significant (p < 0.05) decrease in hepatic granuloma index (-22.1%) and levels of TNF-α (-49.2%) and IL-17 (-57.3%), but a marked increase in IL-22 (64.2%) and IgE (196.1%) levels comparing to non-liposomal IL-22. Three developmental stages of hepatic granuloma (NE, EP, and P) were observed in liposomal and non-liposomal IL-22 groups (79.6 ± 1.7 and 81.8 ± 8.7, respectively, P < 0.05), with higher relative frequency of EP stage. Additionally, liposomal IL-22 treatment increased hepatic expression of STAT3 (21.7 fold change) and let-7a (3.6 fold change) and reduced β-catenin expression (0.6 fold change) compared to healthy mice. Conclusively, liposomal IL-22 seems more effective in the treatment of liver fibrosis resulting from S. mansoni infection than non-liposomal IL-22.

Wnt/beta-catenin signaling and its modulators in nonalcoholic fatty liver diseases

Nonalcoholic fatty liver disease (NAFLD) is a global health concern associated with significant morbidity and mortality. NAFLD is a spectrum of diseases originating from simple steatosis, progressing through nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis that may lead to hepatocellular carcinoma (HCC). The pathogenesis of NAFLD is mediated by the triglyceride accumulation followed by proinflammatory cytokines expression leading to inflammation, oxidative stress, and mitochondrial dysfunction denoted as "two-hit hypothesis", advancing with a "third hit" of insufficient hepatocyte proliferation, leading to the increase in hepatic progenitor cells contributing to fibrosis and HCC. Wnt/β-catenin signaling is responsible for normal liver development, regeneration, hepatic metabolic zonation, ammonia and drug detoxification, hepatobiliary development, etc., maintaining the overall liver homeostasis. The key regulators of canonical Wnt signaling such as LRP6, Wnt1, Wnt3a, β-catenin, GSK-3β, and APC are abnormally regulated in NAFLD. Many experimental studies have shown the aberrated Wnt/β-catenin signaling during the NAFLD progression and NASH to hepatic fibrosis and HCC. Therefore, in this review, we have emphasized the role of Wnt/β-catenin signaling and its modulators that can potentially aid in the inhibition of NAFLD.

Phillygenin Ameliorates Carbon Tetrachloride-Induced Liver Fibrosis: Suppression of Inflammation and Wnt/β-Catenin Signaling Pathway

Liver fibrosis (LF) is caused by the chronic wound healing response to liver injury from various origins. Among the causes, inflammatory response is the central trigger of LF. Phillygenin (PHI) is a lignan derived from Forsythia suspensa, which has significant anti-inflammatory properties. However, the effect of PHI on improving LF and the underlying mechanism have rarely been studied. In this study, we used carbon tetrachloride (CCl₄) to establish a mouse model of LF. Through histological analysis of liver tissue, and measurement of the levels of hepatocyte damage markers (ALT, AST, TBIL, TBA) and four indicators of LF (Col IV, HA, LN, PC-III) in serum, it was shown that PHI improved liver function and reduced the progress of LF. Subsequently, the detection of fibrogenic biomarkers in liver tissue showed that PHI inhibited the activation of hepatic stellate cells (HSCs). Next, the expression of inflammatory markers in liver tissue/serum was detected by immunohistochemistry, RT-qPCR, and ELISA, suggesting that PHI inhibited inflammation during LF. Similarly, in vitro experiments also confirmed that PHI could inhibit lipopolysaccharide-induced inflammatory responses in RAW264.7 cells, which showed strong anti-inflammatory effects. In addition, the results of network pharmacology, molecular docking, RT-qPCR and western blot confirmed that PHI could alleviate CCl₄-induced LF by inhibiting the Wnt/β-catenin pathway. In conclusion, our research showed that PHI curbed LF through inhibition of HSC activation and collagen accumulation via inhibiting multiple profibrogenic factors, modulating a variety of inflammatory factors, and suppressing the Wnt/β-catenin pathway.

The pharmacology and mechanisms of traditional Chinese medicine in promoting liver regeneration: A new therapeutic option

BACKGROUND

The liver is renowned for its remarkable regenerative capacity to restore its structure, size and function after various types of liver injury. However, in patients with end-stage liver disease, the regenerative capacity is inhibited and liver transplantation is the only option. Considering the limitations of liver transplantation, promoting liver regeneration is suggested as a new therapeutic strategy for liver disease. Traditional Chinese medicine (TCM) has a long history of preventing and treating various liver diseases, and some of them have been proven to be effective in promoting liver regeneration, suggesting the therapeutic potential in liver diseases.

PURPOSE

This review aims to summarize the molecular mechanisms of liver regeneration and the pro-regenerative activity and mechanism of TCM formulas, extracts and active ingredients.

METHODS

We conducted a systematic search in PubMed, Web of Science and the Cochrane Library databases using "TCM", "liver regeneration" or their synonyms as keywords, and classified and summarized the retrieved literature. The PRISMA guidelines were followed.

RESULTS

Forty-one research articles met the themes of this review and previous critical studies were also reviewed to provide essential background information. Current evidences indicate that various TCM formulas, extracts and active ingredients have the effect on stimulating liver regeneration through modulating JAK/STAT, Hippo, PI3K/Akt and other signaling pathways. Besides, the mechanisms of liver regeneration, the limitation of existing studies and the application prospect of TCM to promote liver regeneration are also outlined and discussed in this review.

CONCLUSION

This review supports TCM as new potential therapeutic options for promoting liver regeneration and repair of the failing liver, although extensive pharmacokinetic and toxicological studies, as well as elaborate clinical trials, are still needed to demonstrate safety and efficacy.

Epigenetics as a versatile regulator of fibrosis

Fibrosis, a process caused by excessive deposition of extracellular matrix (ECM), is a common cause and outcome of organ failure and even death. Researchers have made many efforts to understand the mechanism of fibrogenesis and to develop therapeutic strategies; yet, the outcome remains unsatisfactory. In recent years, advances in epigenetics, including chromatin remodeling, histone modification, DNA methylation, and noncoding RNA (ncRNA), have provided more insights into the fibrotic process and have suggested the possibility of novel therapy for organ fibrosis. In this review, we summarize the current research on the epigenetic mechanisms involved in organ fibrosis and their possible clinical applications.

Antagonizing EZH2 combined with vitamin D3 exerts a synergistic role in anti-fibrosis through bidirectional effects on hepatocytes and hepatic stellate cells

BACKGROUND AND AIM

Whether vitamin D3 (VD3) supplementation is associated with improved liver fibrosis is controversial.

METHODS

Liver fibrosis models were treated with VD3, active VD (1,25-OH2 Vitamin D3), or collaboration with GSK126 (Ezh2 inhibitor), respectively. Hepatic stellate cells (HSCs) were co-cultured with hepatocytes and then stimulated with TGF-β. Autophagy of hepatocytes was determined after the intervention of 1,25-OH2 Vitamin D3 and GSK126. Also, the active status of HSCs and the mechanism with 1,25-OH2 Vitamin D3 and GSK126 intervention were detected.

RESULTS

1,25-OH2 Vitamin D3, but not VD3, is involved in anti-fibrosis and partially improves liver function, which might be associated with related enzymes and receptors (especially CYP2R1), leading to decreased of its biotransformation. GSK126 plays a synergistic role in anti-fibrosis. The co-culture system showed increased hepatocyte autophagy after HSCs activation. Supplementation with 1,25-OH2 Vitamin D3 or combined GSK126 reduced these effects. Further studies showed that 1,25-OH2 Vitamin D3 promoted H3K27 methylation of DKK1 promoter through VDR/Ezh2 due to the weakening for HSCs inhibitory signal.

CONCLUSIONS

VD3 bioactive form 1,25-OH2 Vitamin D3 is responsible for the anti-fibrosis, which might have bidirectional effects on HSCs by regulating histone modification. The inhibitor of Ezh2 plays a synergistic role in this process.

Exosomal FZD-7 Expression Is Modulated by Different Lifestyle Interventions in Patients with NAFLD

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial condition characterized from hypertriglyceridemia and hepatic fat accumulation, in the absence of alcohol intake. NAFLD starts as steatosis (NAFL), and the continued injury relative to the toxic fat induces inflammation, steatohepatitis (NASH), and HCC. One of the factors determining liver degeneration during the evolution of NAFLD is a modification of Wnt/Frizzled (FZD) signaling. In particular, an inhibition of Wnt signaling and an overexpression of a specific FZD receptor protein, namely, the FZD7, have been observed in NAFLD. Actually, the prognosis and the follow-up of NAFLD is not easy, and the liver biopsy is the gold standard for an accurate detection of liver fibrosis. In this study, the modulation of the FZD7 expression levels in plasma-derived exosomes of NAFLD-affected patients, before and after specific lifestyle interventions, were experimentally evaluated by Western blotting analysis. The experimental data were analyzed by an accurate statistical study that indicated, in the exosomes derived from plasma of NAFLD patients with moderate or severe steatosis, an average expression level of FZD7 that was significantly higher than healthy subjects at baseline; conversely, the values were normalized after 90 days of specific lifestyle interventions. The overall results suggested that the FZD7 delivered by exosomes represents a good candidate as a new and effective biomarker for diagnosis and prognosis of NAFLD.

The role of RNA binding proteins in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of overall cancer deaths worldwide with limited therapeutic options. Due to the heterogeneity of HCC pathogenesis, the molecular mechanisms underlying HCC development are not fully understood. Emerging evidence indicates that RNA-binding proteins (RBPs) play a vital role throughout hepatocarcinogenesis. Thus, a deeper understanding of how RBPs contribute to HCC progression will provide new tools for early diagnosis and prognosis of this devastating disease. In this review, we summarize the tumor suppressive and oncogenic roles of RBPs and their roles in hepatocarcinogenesis. The diagnostic and therapeutic potential of RBPs in HCC, including their limitations, are also discussed.

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

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

Yiguanjian decoction inhibits macrophage M1 polarization and attenuates hepatic fibrosis induced by CCl4/2-AAF

CONTEXT

Our previous studies indicated that Yiguanjian decoction (YGJ) has an anti-hepatic-fibrosis effect and could regulate macrophage status.

OBJECTIVE

To elucidate the mechanism of YGJ in regulating macrophages.

MATERIALS AND METHODS

Liver cirrhosis was induced by CCl4 for 12 weeks combined with 2-acetylaminofluorene (2-AAF) for the last 4 weeks in male Wistar rats. YGJ (3.56 mg/kg) orally administered in the last 4 weeks, and SORA (1 mg/kg) as control. In vitro, RAW264.7 cells were treated with lipopolysaccharides (LPSs) to induce macrophage polarization to the M1 phenotype, and they were co-cultured with WB-F344 cells and allocated to M group, YGJ group (2 μg/mL) and WIF-1 group (1 μg/mL) with untreated cells as control. The differentiation direction of WB-F344 cell line was observed in the presence or absence of YGJ. Pathology, fibrosis-related cytokines, macrophage polarization-related components, and Wnt signalling pathway components were detected.

RESULTS

In vivo, the expression levels of α-SMA, Col (1), OV6, SOX9, EpCAM and M1 macrophage-related components (STAT1, IRF3, IRF5, IRF8, SOCS3) significantly decreased in the YGJ group compared with those in the 2-AAF/CCl4 group (p < 0.01 or 0.05). In vitro, the expression levels of M1 macrophage-related components, including STAT1, NF-κB, IRF3, IRF5, and SOCS3, in RAW264.7 cells decreased significantly in the YGJ group compared with those in the M group (p < 0.05 or p < 0.01). The expression levels of Wnt3A, FZD5, LRP-5/-6, and β-catenin significantly increased in the YGJ group compared with those in the M group (p < 0.05 or p < 0.01). In addition, the expression levels of Wnt-4/-5A/-5B, and FZD2 significantly decreased in the YGJ group compared with those in the M group (p < 0.05 or p < 0.01).

CONCLUSION

This study suggests that the anti-cirrhosis effect of YGJ is associated with its ability to inhibit macrophage M1-polarization, which provides a scientific basis for the clinical application of YGJ.

Cellular and Molecular Mechanisms Underlying Liver Fibrosis Regression

Chronic liver injury of different etiologies may result in hepatic fibrosis, a scar formation process consisting in altered deposition of extracellular matrix. Progression of fibrosis can lead to impaired liver architecture and function, resulting in cirrhosis and organ failure. Although fibrosis was previous thought to be an irreversible process, recent evidence convincingly demonstrated resolution of fibrosis in different organs when the cause of injury is removed. In the liver, due to its high regenerative ability, the extent of fibrosis regression and reversion to normal architecture is higher than in other tissues, even in advanced disease. The mechanisms of liver fibrosis resolution can be recapitulated in the following main points: removal of injurious factors causing chronic hepatic damage, elimination, or inactivation of myofibroblasts (through various cell fates, including apoptosis, senescence, and reprogramming), inactivation of inflammatory response and induction of anti-inflammatory/restorative pathways, and degradation of extracellular matrix. In this review, we will discuss the major cellular and molecular mechanisms underlying the regression of fibrosis/cirrhosis and the potential therapeutic approaches aimed at reversing the fibrogenic process.

Signal Transduction and Molecular Regulation in Fatty Liver Disease

Significance: Fatty liver disease is a major liver disorder in the modern societies. Comprehensive understanding of the pathophysiology and molecular mechanisms is essential for the prevention and treatment of the disease. Recent Advances: Remarkable progress has been made in the recent years in basic and translational research in the field of fatty liver disease. Multiple signaling pathways have been implicated in the development of fatty liver disease, including AMP-activated protein kinase, mechanistic target of rapamycin kinase, endoplasmic reticulum stress, oxidative stress, inflammation, transforming growth factor β, and yes1-associated transcriptional regulator/transcriptional coactivator with PDZ-binding motif (YAP/TAZ). In addition, critical molecular regulations at the transcriptional and epigenetic levels have been linked to the pathogenesis of fatty liver disease. Critical Issues: Some critical issues remain to be solved so that research findings can be translated into clinical applications. Robust and reliable biomarkers are needed for diagnosis of different stages of the fatty liver disease. Effective and safe molecular targets remain to be identified and validated. Prevention strategies require solid scientific evidence and population-wide feasibility. Future Directions: As more data are generated with time, integrative approaches are needed to comprehensively understand the disease pathophysiology and mechanisms at multiple levels from population, organismal system, organ/tissue, to cell. The interactions between genes and environmental factors require deeper investigation for the purposes of prevention and personalized treatment of fatty liver disease. Antioxid. Redox Signal. 35, 689-717.

Extra- and Intra-Cellular Mechanisms of Hepatic Stellate Cell Activation

Hepatic fibrosis is characterized by the pathological accumulation of extracellular matrix (ECM) in the liver resulting from the persistent liver injury and wound-healing reaction induced by various insults. Although hepatic fibrosis is considered reversible after eliminating the cause of injury, chronic injury left unchecked can progress to cirrhosis and liver cancer. A better understanding of the cellular and molecular mechanisms controlling the fibrotic response is needed to develop novel clinical strategies. It is well documented that activated hepatic stellate cells (HSCs) is the most principal cellular players promoting synthesis and deposition of ECM components. In the current review, we discuss pathways of HSC activation, emphasizing emerging extra- and intra-cellular signals that drive this important cellular response to hepatic fibrosis. A number of cell types and external stimuli converge upon HSCs to promote their activation, including hepatocytes, liver sinusoidal endothelial cells, macrophages, cytokines, altered ECM, hepatitis viral infection, enteric dysbiosis, lipid metabolism disorder, exosomes, microRNAs, alcohol, drugs and parasites. We also discuss the emerging signaling pathways and intracellular events that individually or synergistically drive HSC activation, including TGFβ/Smad, Notch, Wnt/β-catenin, Hedgehog and Hippo signaling pathways. These findings will provide novel potential therapeutic targets to arrest or reverse fibrosis and cirrhosis.

Adipose-PAS interactions in the context of its localised bio-engineering potential (Review)

Adipocytes are a known source of stem cells. They are easy to harvest, and are a suitable candidate for autogenous grafts. Adipose derived stem cells (ADSCs) have multiple target tissues which they can differentiate into, including bone and cartilage. In adipose tissue, ADSCs are able to differentiate, as well as providing energy and a supply of cytokines/hormones to manage the hypoxic and lipid/hormone saturated adipose environment. The plasminogen activation system (PAS) controls the majority of proteolytic activities in both adipose and wound healing environments, allowing for rapid cellular migration and tissue remodelling. While the primary activation pathway for PAS occurs through the urokinase plasminogen activator (uPA), which is highly expressed by endothelial cells, its function is not limited to enabling revascularisation. Proteolytic activity is dependent on protease activation, localisation, recycling mechanisms and substrate availability. uPA and uPA activated plasminogen allows pluripotent cells to arrive to new local environments and fulfil the niche demands. However, overstimulation, the acquisition of a migratory phenotype and constant protein turnover can be unconducive to the formation of structured hard and soft tissues. To maintain a suitable healing pattern, the proteolytic activity stimulated by uPA is modulated by plasminogen activator inhibitor 1. Depending on the physiological settings, different parts of the remodelling mechanism are activated with varying results. Utilising the differences within each microenvironment to recreate a desired niche is a valid therapeutic bio-engineering approach. By controlling the rate of protein turnover combined with a receptive stem cell lineage, such as ADSC, a novel avenue on the therapeutic opportunities may be identified, which can overcome limitations, such as scarcity of stem cells, low angiogenic potential or poor host tissue adaptation.

The Emerging Role of Sfrp5 and Wnt5a in the Pathogenesis of Obesity: Implications for a Healthy Diet and Lifestyle

In recent decades, the prevalence of obesity has risen dramatically worldwide among all age groups. Obesity is characterized by excess fat accumulation and chronic low-grade inflammation. The adipose tissue functions as a metabolically active endocrine organ secreting adipokines. A novel duo of adipokines, the anti-inflammatory secreted frizzled-related protein 5 (Sfrp5) and the proinflammatory wingless type mouse mammary tumor virus (MMTV) integration site family member 5A (Wnt5a), signal via the non-canonical Wnt pathway. Recent evidence suggests that Sfpr5 and Wnt5a play a key role in the pathogenesis of obesity and its metabolic complications. This review summarizes the current knowledge on the novel regulatory system of anti-inflammatory Sfrp5 and pro-inflammatory Wnt5a, and their relation to obesity and obesity-related complications. Future studies are required to investigate the potential role of Sfrp5 and Wnt5a as biomarkers for monitoring the response to lifestyle interventions and for predicting the development of cardiometabolic risk factors. These adipokines may also serve as novel therapeutic targets for obesity-related disorders.

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

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

Paternal nicotine exposure promotes hepatic fibrosis in offspring

Paternal nicotine exposure can alter phenotypes in future generations. The aim of this study is to explore whether paternal nicotine exposure affects the hepatic repair to chronic injury which leads to hepatic fibrosis in offspring. Our results demonstrate that nicotine down regulates mmu-miR-15b expression via the hyper-methylation on its CpG island shore region in the spermatozoa. This epigenetic modification imprinted in the liver of the offspring. The decreased mmu-miR-15b promotes the expression of Wnt4 and activates the Wnt pathway in the offspring mice liver. The activation of the Wnt pathway improves the activation and proliferation of hepatic stellate cells (HSCs) leading to liver fibrosis. Moreover, the Wnt pathway promotes the activation of the TGF-β pathway and the two pathways cooperate to promote the transcription of extracellular matrix (ECM) genes. In conclusion, this study found that nicotine promotes hepatic fibrosis in the offspring via the activation of Wnt pathway by imprinting the hyper-methylation of mmu-miR-15b.

Association of Adipose Tissue and Adipokines with Development of Obesity-Induced Liver Cancer

Obesity is rapidly dispersing all around the world and is closely associated with a high risk of metabolic diseases such as insulin resistance, dyslipidemia, and nonalcoholic fatty liver disease (NAFLD), leading to carcinogenesis, especially hepatocellular carcinoma (HCC). It results from an imbalance between food intake and energy expenditure, leading to an excessive accumulation of adipose tissue (AT). Adipocytes play a substantial role in the tumor microenvironment through the secretion of several adipokines, affecting cancer progression, metastasis, and chemoresistance via diverse signaling pathways. AT is considered an endocrine organ owing to its ability to secrete adipokines, such as leptin, adiponectin, resistin, and a plethora of inflammatory cytokines, which modulate insulin sensitivity and trigger chronic low-grade inflammation in different organs. Even though the precise mechanisms are still unfolding, it is now established that the dysregulated secretion of adipokines by AT contributes to the development of obesity-related metabolic disorders. This review focuses on several obesity-associated adipokines and their impact on obesity-related metabolic diseases, subsequent metabolic complications, and progression to HCC, as well as their role as potential therapeutic targets. The field is rapidly developing, and further research is still required to fully understand the underlying mechanisms for the metabolic actions of adipokines and their role in obesity-associated HCC.

Role of long non‑coding RNAs and related epigenetic mechanisms in liver fibrosis (Review)

Liver fibrosis is one of the major liver pathologies affecting patients worldwide. It results from an improper tissue repair process following liver injury or inflammation. If left untreated, it ultimately leads to liver cirrhosis and liver failure. Long non‑coding RNAs (lncRNAs) have been implicated in a wide variety of diseases. They can regulate gene expression and modulate signaling. Some of the lncRNAs promote, while others inhibit liver fibrosis. Similarly, other epigenetic processes, such as methylation and acetylation regulate gene transcription and can modulate gene expression. Notably, there are several regulatory associations of lncRNAs with other epigenetic processes. A major mechanism of action of long non‑coding RNAs is to competitively bind to their target microRNAs (miRNAs or miRs), which in turn affects miRNA availability and bioactivity. In the present review, the role of lncRNAs and related epigenetic processes contributing to liver fibrosis is discussed. Finally, various potential therapeutic approaches targeting lncRNAs and related epigenetic processes, which are being considered as possible future treatment targets for liver fibrosis are identified.

Physalin D attenuates hepatic stellate cell activation and liver fibrosis by blocking TGF-β/Smad and YAP signaling

BACKGROUND

Hepatic fibrosis is considered integral to the progression of chronic liver diseases, as it leads to the development of cirrhosis and hepatocellular carcinoma. The activation of hepatic stellate cells (HSCs) is the dominant event in hepatic fibrogenesis. The transforming growth factor-β1 (TGF-β1) and Yes-associated protein (YAP) pathways play a pivotal role in HSC activation, hepatic fibrosis and cirrhosis progression. Therefore, targeting the TGF-β/Smad and YAP signaling pathways is a promising strategy for antifibrotic therapy.

PURPOSE

The present study investigated the protective effects of Physalin D (PD), a withanolide isolated from Physalis species (Solanaceae), against liver fibrosis and further elucidated the mechanisms involved in vitro and in vivo.

STUDY DESIGN/METHODS

We conducted a series of experiments using carbon tetrachloride (CCl₄)- and bile duct ligation (BDL)-induced fibrotic mice and cultured LX-2 cells. Serum markers of liver injury, and the morphology, histology and fibrosis of liver tissue were investigated. Western blot assays and quantitative real-time PCR were used to investigate the mechanisms underlying the antifibrotic effects of PD.

RESULT

PD decreased TGF-β1-induced COL1A1 promoter activity. PD inhibited TGF-β1-induced expression of Collagen I and α-smooth muscle actin (α-SMA) in human hepatic stellate LX-2 cells. PD significantly ameliorated hepatic injury, including transaminase activities, histology, collagen deposition and α-SMA, in CCl₄- or BDL-induced mice. Moreover, PD markedly decreased the expression of phosphorylated Smad2/3 in vitro and in vivo. Furthermore, PD significantly decreased YAP protein levels, and YAP knockdown did not further enhance the effects of PD, namely α-SMA inhibition, Collagen I expression and YAP target gene expression in LX-2 cells.

CONCLUSION

These results clearly show that PD ameliorated experimental liver fibrosis by inhibiting the TGF-β/Smad and YAP signaling pathways, indicating that PD has the potential to effectively treat liver fibrosis.

Targeting chromatin dysregulation in organ fibrosis

Fibrosis leads to destruction of organ architecture accompanied by chronic inflammation and loss of function. Fibrosis affects nearly every organ in the body and accounts for ∼45% of total deaths worldwide. Over the past decade, tremendous progress has been made in understanding the basic mechanisms leading to organ fibrosis. However, we are limited with therapeutic options and there is a significant need to develop highly effective anti-fibrotic therapies. Recent advances in sequencing technologies have advanced the burgeoning field of epigenetics towards molecular understanding at a higher resolution. Here we provide a comprehensive review of the recent advances in chromatin regulatory processes, specifically DNA methylation, post-translational modification of histones, and chromatin remodeling complexes in kidney, liver and lung fibrosis. Although this research field is young, we discuss new strategies for potential therapeutic interventions for treating organ fibrosis.

Space of Disse: a stem cell niche in the liver

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

Inhibition of p66Shc Oxidative Signaling via CA-Induced Upregulation of miR-203a-3p Alleviates Liver Fibrosis Progression

We previously found that inhibition of p66Shc confers protection against hepatic stellate cell (HSC) activation during liver fibrosis. However, the effect of p66Shc on HSC proliferation, as well as the mechanism by which p66Shc is modulated, remains unknown. Here, we elucidated the effect of p66Shc on HSC proliferation and evaluated microRNA (miRNA)-p66Shc-mediated reactive oxidative species (ROS) generation in liver fibrosis. An in vivo model of carbon tetrachloride (CCl₄)-induced liver fibrosis in rats and an LX-2 cell model were developed. p66Shc expression was significantly upregulated in rats with CCl₄-induced liver fibrosis and in human fibrotic livers. Additionally, p66Shc knockdown in vitro attenuated mitochondrial ROS generation and HSC proliferation. Interestingly, p66Shc promoted HSC proliferation via β-catenin dephosphorylation in vitro. MicroRNA (miR)-203a-3p, which was identified by microarray and bioinformatics analyses, directly inhibited p66Shc translation and attenuated HSC proliferation in vitro. Importantly, p66Shc was found to play an indispensable role in the protective effect of miR-203a-3p. Furthermore, carnosic acid (CA), the major antioxidant compound extracted from rosemary leaves, protected against CCl₄-induced liver fibrosis through the miR-203a-3p/p66Shc axis. Collectively, these results suggest that p66Shc, which is directly suppressed by miR-203a-3p, is a key regulator of liver fibrosis. This finding may lead to the development of therapeutic targets for liver fibrosis.

Differentially expressed mRNAs and lncRNAs shared between activated human hepatic stellate cells and nash fibrosis

We previously reported dysregulated expression of liver-derived messenger RNA (mRNA) and long noncoding RNA (lncRNA) in patients with advanced fibrosis resulting from nonalcoholic fatty liver disease (NAFLD). Here we sought to identify changes in mRNA and lncRNA levels associated with activation of hepatic stellate cells (HSCs), the predominant source of extracellular matrix production in the liver and key to NAFLD-related fibrogenesis. We performed expression profiling of mRNA and lncRNA from LX-2 cells, an immortalized human HSC cell line, treated to induce phenotypes resembling quiescent and myofibroblastic states. We identified 1964 mRNAs (1377 upregulated and 587 downregulated) and 1460 lncRNAs (665 upregulated and 795 downregulated) showing statistically significant evidence (FDR ≤0.05) for differential expression (fold change ≥|2|) between quiescent and activated states. Pathway analysis of differentially expressed genes showed enrichment for hepatic fibrosis (FDR = 1.35E-16), osteoarthritis (FDR = 1.47E-14), and axonal guidance signaling (FDR = 1.09E-09). We observed 127 lncRNAs/nearby mRNA pairs showing differential expression, the majority of which were dysregulated in the same direction. A comparison of differentially expressed transcripts in LX-2 cells with RNA-sequencing results from NAFLD patients with or without liver fibrosis revealed 1047 mRNAs and 91 lncRNAs shared between the two datasets, suggesting that some of the expression changes occurring during HSC activation can be observed in biopsied human tissue. These results identify lncRNA and mRNA expression patterns associated with activated human HSCs that appear to recapitulate human NAFLD fibrosis.

Heme Oxygenase-1 Suppresses Wnt Signaling Pathway in Nonalcoholic Steatohepatitis-Related Liver Fibrosis

Methods

Mice were fed with a methionine-choline-deficient (MCD) diet for 8 weeks to induce steatohepatitis-related liver fibrosis and were treated with HO-1 inducer Hemin and inhibitor ZnPP. Mouse sera were collected for the biochemical analysis, and livers were obtained for further histological observation and gene expression analysis. HSC-T6 cells were cultured for the in vitro study and were administrated with Hemin and si-HO-1 to induce or inhibit the expression of HO-1. qPCR and Western blot were used to assess the mRNA and protein levels of genes.

Results

MCD-fed mice developed marked macrovesicular steatosis, focal necrosis, and inflammatory infiltration and pericellular fibrosis in liver sections. Administration of Hemin could significantly ameliorate the severity of steatosis, inflammation, and fibrosis and also could decrease the serum ALT and AST. We demonstrated that HO-1 induction was able to downregulate the key regulator of the canonical Wnt pathway Wnt1 and the noncanonical Wnt pathway Wnt5a. The downstream factors of the Wnt pathway β-catenin and NFAT5 were inhibited by Hemin, but GSK-3β was upregulated compared to the MCD group, which were consistent with the in vitro study. Hemin markedly inhibited the TGF-β1/Smad signaling pathway in both in vivo and in vitro studies.

Conclusion

Our study demonstrated that HO-1 inhibited the activation of canonical and noncanonical Wnt signaling pathways in NASH-related liver fibrosis. Thus, these results may suggest a new therapeutic strategy for NASH-related liver fibrosis.

Analysis of piRNA expression spectra in a non-alcoholic fatty liver disease mouse model induced by a methionine- and choline-deficient diet

Non-alcoholic fatty liver disease (NAFLD) has become a common health issue worldwide, and P-element-induced wimpy testis (PIWI)-interacting RNAs (piRNAs) have been shown to be differentially expressed in a variety of diseases. The aim of the present study was to investigate the potential relationship between piRNA and NAFLD. A NAFLD mouse model was established using a methionine- and choline-deficient (MCD) diet and methionine- and choline-sufficient (MCS) diet. Following this, mouse liver tissues were removed and stained with hematoxylin and eosin, and the levels of alanine aminotransferase, aspartate aminotransferase, total cholesterol and triglyceride were measured. Moreover, the liver tissues of the control and model groups were selected for piRNA gene chip analysis to identify piRNAs with differential expression in NAFLD. In addition, the differentially expressed piRNAs screened from the microarray were assessed by reverse transcription-quantitative PCR (RT-qPCR). piRNAs with potential research value were also selected for further analysis of target genes, using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways. The present study identified a total of 1,285 piRNAs with differential expression levels. The results indicated that in the model group, 641 piRNAs were upregulated, while 644 piRNAs were downregulated. Furthermore, piRNAs were enriched in ‘cancer’, ‘Hippo signaling’, ‘Wnt signaling’ and ‘Mitogen-activated protein kinase signaling’ pathways. The RT-qPCR results demonstrated that piRNA DQ566704 and piRNA DQ723301 were significantly upregulated in the model group, which was largely consistent with the analysis results of the piRNA arrays. Therefore, the results of the piRNA arrays and the further analyses in the present study were considered reliable. Collectively, the present results suggest that differentially expressed piRNAs exist in NAFLD and may affect the development of NAFLD via related pathways.

A MicroRNA Derived From Schistosoma japonicum Promotes Schistosomiasis Hepatic Fibrosis by Targeting Host Secreted Frizzled-Related Protein 1

Schistosomiasis remains a serious parasitic disease, which is characterized by granulomatous inflammation and hepatic fibrosis. MicroRNAs derived from parasites can regulate host genes and cell phenotype. Here, we showed that a miRNA derived from S. japonicum (Sja-miR-1) exists in the hepatic stellate cells (HSCs) of mice infected with the parasite and up-regulates the expression of collagens and α-SMA by targeting secreted frizzled-related protein 1 (SFRP1). A vector-mediated delivery of Sja-miR-1 into naive mice led to hepatic fibrogenesis in the mice. Accordingly, inhibition of Sja-miR-1 in the infected mice led to reduction of the parasite-induced hepatic fibrosis. The mechanism behind the Sja-miR-1-mediated activation of HSC could be through targeting SFRP1 to regulate the Wnt/β-catenin pathway. These findings reveal that parasite-derived small non-coding RNAs are implicated in cross-species regulation of host pathological process and persistent inhibition of Sja-miR-1 may provide a therapeutic potential for the parasite diseases.

Stearoyl-CoA desaturase and tumorigenesis

Stearoyl-CoA desaturase (SCD) generates monounsaturated fatty acids (MUFAs) which contribute to cell growth, survival, differentiation, metabolic regulation and signal transduction. Overexpression of SCD is evident and implicated in metabolic diseases such as diabetes and non-alcoholic fatty liver disease. SCD also stimulates canonical Wnt pathway and YAP activation in support of stemness and tumorigenesis. SCD facilitates metabolic reprogramming in cancer which is mediated, at least in part, by regulation of AKT, AMPK, and NF-kB via MUFAs. Our research has revealed the novel positive loop to amplify Wnt signaling through stabilization of LRP5/6 in both hepatic stellate cells and liver tumor-initiating stem cell-like cells. As such, this loop is pivotal in promoting liver fibrosis and liver tumor development. This review summarizes the mechanisms of SCD-mediated tumor promotion described by recent studies and discusses the future prospect for SCD-mediated signaling crosstalk as a potential therapeutic target for cancer.

Expression analysis of microRNAs and mRNAs in myofibroblast differentiation of lung resident mesenchymal stem cells

Idiopathic pulmonary fibrosis (IPF) is a serious lung disease that involved the myofibroblast differentiation of lung resident mesenchymal stem cells (LR-MSCs). However, the specific molecular mechanisms of myofibroblast differentiation of LR-MSCs still remain a mystery. In this study, a comprehensive analysis of miRNAs and mRNAs changes in LR-MSCs treated with TGF-β1 was performed. Through computational approaches, the pivotal roles of differentially expressed miRNAs that were associated with tight junction, pathways in cancer, focal adhesion, and cytokine-cytokine receptor interaction were shown. Kruppel-like factor 4 (Klf4) and inhibitor of growth family, member 5 (Ing5) may be the targets for the therapy of pulmonary fibrosis by inhibiting myofibroblast differentiation of LR-MSCs and EMT. Collectively, a molecular paradigm for understanding myofibroblast differentiation of LR-MSCs in IPF was provided by the integrated miRNA/mRNA analyses.

The interaction between microRNA-152 and DNA methyltransferase-1 as an epigenetic prognostic biomarker in HCV-induced liver cirrhosis and HCC patients

The necessity for early detection and hence improving the outcome of treatment of hepatocellular carcinoma (HCC) is critical especially in Hepatitis C virus (HCV)-Genotype 4 induced cases. In our current work, we examined the miRNA-152 and DNMT-1 expression in chronic liver disease (CLD) due to HCV genotype 4 infection with/without cirrhosis and HCC patients as an attempt to evaluate the potential benefits of these new circulating, noninvasive, prognostic, epigenetic markers for liver cirrhosis and carcinogenesis of Egyptian patients. Eighty subjects were included in this study, divided into two groups; group I (40 patients) were classified into subgroup Ia (CLD without cirrhosis, n = 18) and subgroup Ib (CLD with cirrhosis, n = 22), group II (CLD patients with HCC, n = 20), and control (Healthy volunteer, n = 20). The expression of miRNA-152 and DNMT-1 genes were analyzed using Real-Time PCR. MiRNA-152 showed a persistent and significant downregulation in all diseased groups, which was in consistence with the progression of the disease toward the HCC stage. DNMT-1 showed upregulation in all diseased groups when compared to control and subgroup Ia. The miRNA-152 was shown to correlate inversely with DNMT-1 in subgroup Ia, Ib and group II (r = -0.557, p < 0.01), (r = -0.850, p < 0.001) and (r = -0.544, p < 0.02) respectively. In addition, miRNA-152 and DNMT-1 showed a diagnostic ability to discriminate between cases of cirrhosis and HCC against CLD without cirrhosis (p < 0.01), while DNMT-1 did not, except between HCC and cirrhotic cases. Furthermore, both genes can be considered as predictor and prognostic parameters for cirrhosis (OR = 1.041, p = 0.043) and (OR = 1.039, p = 0.04) respectively, while miRNA-152 alone is proved as a prognostic marker for HCC (OR = 1.003, p = 0.044). Finally, the persistent reverse correlation between miRNA-152 with DNMT-1 prompts their use as noninvasive prognostic biomarkers for HCV induced liver cirrhosis and HCC in HCV Genotype 4 patients.

Overexpression of miRNA-25-3p inhibits Notch1 signaling and TGF-β-induced collagen expression in hepatic stellate cells

During chronic liver injury hepatic stellate cells (HSCs), the principal source of extracellular matrix in the fibrotic liver, transdifferentiate into pro-fibrotic myofibroblast-like cells - a process potentially regulated by microRNAs (miRNAs). Recently, we found serum miRNA-25-3p (miR-25) levels were upregulated in children with Cystic Fibrosis (CF) without liver disease, compared to children with CF-associated liver disease and healthy individuals. Here we examine the role of miR-25 in HSC biology. MiR-25 was detected in the human HSC cell line LX-2 and in primary murine HSCs, and increased with culture-induced activation. Transient overexpression of miR-25 inhibited TGF-β and its type 1 receptor (TGFBR1) mRNA expression, TGF-β-induced Smad2 phosphorylation and subsequent collagen1α1 induction in LX-2 cells. Pull-down experiments with biotinylated miR-25 revealed Notch signaling (co-)activators ADAM-17 and FKBP14 as miR-25 targets in HSCs. NanoString analysis confirmed miR-25 regulation of Notch- and Wnt-signaling pathways. Expression of Notch signaling pathway components and endogenous Notch1 signaling was downregulated in miR-25 overexpressing LX-2 cells, as were components of Wnt signaling such as Wnt5a. We propose that miR-25 acts as a negative feedback anti-fibrotic control during HSC activation by reducing the reactivity of HSCs to TGF-β-induced collagen expression and modulating the cross-talk between Notch, Wnt and TGF-β signaling.

Epigenetic Mechanisms in Hepatic Stellate Cell Activation During Liver Fibrosis and Carcinogenesis

Liver fibrosis is an essential component of chronic liver disease (CLD) and hepatocarcinogenesis. The fibrotic stroma is a consequence of sustained liver damage combined with exacerbated extracellular matrix (ECM) accumulation. In this context, activation of hepatic stellate cells (HSCs) plays a key role in both initiation and perpetuation of fibrogenesis. These cells suffer profound remodeling of gene expression in this process. This review is focused on the epigenetic alterations participating in the transdifferentiation of HSCs from the quiescent to activated state. Recent advances in the field of DNA methylation and post-translational modifications (PTM) of histones (acetylation and methylation) patterns are discussed here, together with altered expression and activity of epigenetic remodelers. We also consider recent advances in translational approaches, including the use of epigenetic marks as biomarkers and the promising antifibrotic properties of epigenetic drugs that are currently being used in patients.

Elimination of Wnt Secretion From Stellate Cells Is Dispensable for Zonation and Development of Liver Fibrosis Following Hepatobiliary Injury

Alterations in the Wnt signaling pathway including those impacting hepatic stellate cells (HSCs) have been implicated in liver fibrosis. In the current study, we first examined the expression of Wnt genes in human HSC (HHSCs) after treatment with a profibrogenic factor TGF-β1. Next, we generated HSC-specific Wntless (Wls) knockout (KO) using the Lrat-cre and Wls-floxed mice. KO and littermate controls (CON) were characterized for any basal phenotype and subjected to two liver fibrosis protocols. In vitro, TGF-β1 induced expression of Wnt2, 5a and 9a while decreasing Wnt2b, 3a, 4, and 11 in HHSC. In vivo, KO and CON mice were born at normal Mendelian ratio and lacked any overt phenotype. Loss of Wnt secretion from HSCs had no effect on liver weight and did not impact β-catenin activation in the pericentral hepatocytes. After 7 days of bile duct ligation (BDL), KO and CON showed comparable levels of serum alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, total and direct bilirubin. Comparable histology, Sirius red staining, and immunohistochemistry for α-SMA, desmin, Ki-67, F4/80, and CD45 indicated similar proliferation, inflammation, and portal fibrosis in both groups. Biweekly administration of carbon tetrachloride for 4 or 8 weeks also led to comparable serum biochemistry, inflammation, and fibrosis in KO and CON. Specific Wnt genes were altered in HHSCs in response to TGF-β1; however, eliminating Wnt secretion from HSC did not impact basal β-catenin activation in normal liver nor did it alter the injury-repair response during development of liver fibrosis.

Repression of liver cirrhosis achieved by inhibitory effect of miR-454 on hepatic stellate cells activation and proliferation via Wnt10a

As is known, hepatic stellate cells (HSCs) activation contributes to liver cirrhosis. This study aims to find out the acting mechanisms of miR-454 inhibiting the activation and proliferation of hepatic stellate cells. The expression of Col1A1, α-smooth muscle actin (α-SMA) and Wnt10a were determined by western blot, and the miR-454 level was determined by quantitative real-time PCR in this study. We took two objects as experiment subjects, one was liver cirrhosis rats, and the other was transforming growth factor (TGF)-β1-stimulated HSC-T6 cells. After activated with TGF-β1 and transfected with microRNA-454 mimic, separately or successively, the changes on the Col1A1 and α-SMA expression, HSC proliferation, miR-454 level and Wnt10a expression were examined in HSC-T6 cells, respectively. Interaction between miR-454 and Wnt10a was evaluated with dual luciferase reporter assay. MiR-454 expression was down-regulated in tissues of liver cirrhosis rats. TGF-β1 caused the down-regulation of the miR-454 in HSC-T6 cells. MiR-454 inhibited the activation and proliferation of HSC-T6 cells. Wnt10a had a targeting relationship with miR-454. TGF-β1 promoted HSC-T6 activation and proliferation via down-regulating miR-454 expression, which further up-regulated Wnt10a expression. MiR-454 mimic inhibited cirrhosis progression in liver cirrhosis rats. MiR-454 can inhibit the activation and proliferation of HSCs via suppressing the expression of Wnt10a, to restrain liver cirrhosis.

Wnt-β-catenin signalling in liver development, health and disease

The canonical Wnt-β-catenin pathway is a complex, evolutionarily conserved signalling mechanism that regulates fundamental physiological and pathological processes. Wnt-β-catenin signalling tightly controls embryogenesis, including hepatobiliary development, maturation and zonation. In the mature healthy liver, the Wnt-β-catenin pathway is mostly inactive but can become re-activated during cell renewal and/or regenerative processes, as well as in certain pathological conditions, diseases, pre-malignant conditions and cancer. In hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), the two most prevalent primary liver tumours in adults, Wnt-β-catenin signalling is frequently hyperactivated and promotes tumour growth and dissemination. A substantial proportion of liver tumours (mainly HCC and, to a lesser extent, CCA) have mutations in genes encoding key components of the Wnt-β-catenin signalling pathway. Likewise, hepatoblastoma, the most common paediatric liver cancer, is characterized by Wnt-β-catenin activation, mostly as a result of β-catenin mutations. In this Review, we discuss the most relevant molecular mechanisms of action and regulation of Wnt-β-catenin signalling in liver development and pathophysiology. Moreover, we highlight important preclinical and clinical studies and future directions in basic and clinical research.

Autocrine CTHRC1 activates hepatic stellate cells and promotes liver fibrosis by activating TGF-β signaling

BACKGROUND

Hepatic fibrosis is caused by chronic liver injury and may progress toward liver cirrhosis, and even hepatocellular carcinoma. However, current treatment is not satisfactory. Therefore, there is a mandate to find novel therapeutic targets to improve therapy, and biomarkers to monitor therapeutic response.

METHODS

Liver fibrosis was induced by carbon tetrachloride (CCl4) or thioacetamide (TAA) in wild type (WT) or CTHRC1-/- mice, followed by immunofluorescence and immunohistochemical analyses. CTHRC1 monoclonal antibody (mAb) was used to abrogate the effect of CTHRC1 in vitro and in vivo.

RESULTS

Here, we reported that collagen triple helix repeat containing 1 (CTHRC1), a secreted protein derived from hepatic stellate cells (HSCs), was significantly up-regulated in fibrotic liver tissues. CTHRC1 promoted HSCs transformation from a quiescent to an activated state, and enhanced migratory or contractile capacities of HSCs by activating TGF-β signaling. Meanwhile, CTHRC1 competitively bound to Wnt noncononical receptor and promoted the contractility but not activation of HSCs. CCl4 or TAA-induced liver fibrosis was attenuated in CTHRC-/- mice compared with littermate control, while a monoclonal antibody of CTHRC1 suppressed liver fibrosis in WT mice treated with CCl4 or TAA.

INTERPRETATION

We demonstrated that CTHRC1 is a new regulator of liver fibrosis by modulating TGF-β signaling. Targeting CTHRC1 could be a promising therapeutic approach, which can suppress TGF-β signaling and avoid the side effects caused by directly targeting TGF-β. CTHRC1 could also be a potential biomarker for monitoring response to anti-fibrotic therapy. FUND: This study was supported by the National Natural Science Foundation of China (ID 81672358, 81871923, 81872242, 81802890), the Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support (ID 20181708), the Natural Science Foundation of Shanghai (ID 17ZR1428300, 18ZR1436900), and Shanghai Municipal Health Bureau (ID 2018BR32). The funders did not play a role in manuscript design, data collection, data analysis, interpretation nor writing of the manuscript.

Yiguanjian decoction enhances fetal liver stem/progenitor cell-mediated repair of liver cirrhosis through regulation of macrophage activation state

AIM

To investigate whether Yiguanjian decoction (YGJ) has an anti-liver cirrhotic effect and whether it regulates hepatic stem cell differentiation.

METHODS

A rat model of liver cirrhosis was established via subcutaneous injection of carbon tetrachloride (CCl4) for 8 wk. From the beginning of the ninth week, the rats received 2-acetylaminofluorene (2-AAF) by oral gavage and a DLK-1+ fetal liver stem/progenitor cell (FLSPC) transplant or an FLSPC transplant in combination with YGJ treatment for 4 wk. In vitro, lipopolysaccharide (LPS)-activated macrophages were co-cultured with WB-F344 cells, and the differentiation of WB-F344 cells was observed in the presence and absence of YGJ treatment.

RESULTS

FLSPC transplantation improved liver function and histopathology, and inhibited the activation of the non-canonical Wnt signaling pathway, while activating the canonical Wnt signaling pathway. YGJ enhanced the therapeutic effects of FLSPCs and also promoted the liver regeneration differentiation of FLSPCs into hepatocytes. In vitro, LPS-activated macrophages promoted the differentiation of WB-F344 cells into myofibroblasts, and the canonical Wnt signaling was inhibited while the non-canonical Wnt signaling was activated in WB-F344 cells. YGJ suppressed the activation of macrophages and then inhibited non-canonical Wnt signaling and promoted canonical Wnt signaling.

CONCLUSION

YGJ enhances FLSPC-mediated repair of liver cirrhosis through regulation of macrophage activation state, and YGJ in combination with stem cell transplantation may be a suitable treatment for end-stage liver cirrhosis.

Cellular network modeling and single cell gene expression analysis reveals novel hepatic stellate cell phenotypes controlling liver regeneration dynamics

Background

Recent results from single cell gene and protein regulation studies are starting to uncover the previously underappreciated fact that individual cells within a population exhibit high variability in the expression of mRNA and proteins (i.e., molecular variability). By combining cellular network modeling, and high-throughput gene expression measurements in single cells, we seek to reconcile the high molecular variability in single cells with the relatively low variability in tissue-scale gene and protein expression and the highly coordinated functional responses of tissues to physiological challenges. In this study, we focus on relating the dynamic changes in distributions of hepatic stellate cell (HSC) functional phenotypes to the tightly regulated physiological response of liver regeneration.

Results

We develop a mathematical model describing contributions of HSC functional phenotype populations to liver regeneration and test model predictions through isolation and transcriptional characterization of single HSCs. We identify and characterize four HSC transcriptional states contributing to liver regeneration, two of which are described for the first time in this work. We show that HSC state populations change in vivo in response to acute challenges (in this case, 70% partial hepatectomy) and chronic challenges (chronic ethanol consumption). Our results indicate that HSCs influence the dynamics of liver regeneration through steady-state tissue preconditioning prior to an acute insult and through dynamic control of cell state balances. Furthermore, our modeling approach provides a framework to understand how balances among cell states influence tissue dynamics.

Conclusions

Taken together, our combined modeling and experimental studies reveal novel HSC transcriptional states and indicate that baseline differences in HSC phenotypes as well as a dynamic balance of transitions between these phenotypes control liver regeneration responses.

Electronic supplementary material

The online version of this article (10.1186/s12918-018-0605-7) contains supplementary material, which is available to authorized users.

TMEM9 mediates IL-6 and IL-1β secretion and is modulated by the Wnt pathway

Novel studies have shown that the Transmembrane protein 9 (TMEM9) gene is localized at 1q41 and encodes a protein consisting of 183 amino acids with an N-terminus containing many important domains. As a novel human transmembrane protein, TMEM9 is highly conserved in species from Caenorhabditis elegans to humans and is widely expressed in many tissues and cells. Moreover, TMEM9 may play an important role in intracellular transport and the growth of hepatoma cells. However, evidence for the function of TMEM9 in inflammation is still limited. We studied the expression of TMEM9 and its effect on cytokine secretion in tumor necrosis factor-alpha (TNF-α)-induced LX-2 cells. We proved that overexpression of TMEM9 by transfection with pEGFP-C2-TMEM9 may increase the expression of IL-6 and IL-1β in LX-2 cells. At the same time, knockdown of TMEM9 expression by transfection with a TMEM9-siRNA decreased IL-6 and IL-1β secretion in LX-2 cells. Additionally, our results proved that overexpression of TMEM9 enhanced the protein expression levels of the canonical Wnt/β-catenin accompanied by an upregulation of wnt2b, wnt3a and β-catenin protein levels in LX-2 cells treated with TNF-α. These results indicate that TMEM9 plays a significant role in TNF-α-enhanced cytokines (IL-6 and IL-1β) secretion in LX-2 cells and that the canonical Wnt/β-catenin signaling pathway is involved in the induction of these cytokine expressions.

Cell-laden and orthogonal-multilayer tissue-engineered corneal stroma induced by a mechanical collagen microenvironment and transplantation in a rabbit model

The development of functional therapies for corneal repair and regeneration is a pressing issue. Corneal stroma provides the principal functions of the cornea. However, because of the highly organized nature of the stromal matrix, the attempts to reproduce corneal stroma might follow a scar model. Here, we have developed a protocol for the efficient generation of a cell-laden and orthogonal-multilayer tissue-engineered (TE) corneal stroma, which is induced by the mechanical effects of compressed collagen (CC) or stretched compressed collagen (SCC). Within SCC, with applied compression and force extension, collagen microfibres and corneal stromal cells (CSCs) are arranged orderly, while collagen fibres and CSCs in CC are randomly arranged. Dehydrated SCC has higher tensile strength than dehydrated CC. Hydrated SCC has similar transparency with hydrated native corneal stroma. Compared with those cultured on tissue culture plates (TCP), down-regulation of the genes and proteins of cytoskeleton, activation, proliferation, collagen and TRPV4, up-regulation of proteoglycans, gap junction proteins and TRPA1 are in CSCs of CC and SCC. Moreover, SCC and CC grafts displayed biocompatibility and integration with host corneal tissue after rabbit intra-corneal stromal transplantation by wk 6 under slit lamp microscopy, in vivo confocal microscopy and histological examination. The SCC model facilitates the construction of physiological feature TE corneal stroma, which serves as a foundation for physiological TE construction of other tissues.

STATEMENT OF SIGNIFICANCE

The development of functional therapies for corneal repair and regeneration is a pressing issue. Corneal stroma provides the principal functions of the cornea. Here, we have developed a protocol for the efficient generation of a cell-laden and orthogonal-multilayer tissue-engineered (TE) corneal stroma, which is induced by the mechanical effects of compressed collagen (CC) or stretched compressed collagen (SCC). These models facilitate the construction of physiological feature TE corneal stroma, which serves as a foundation for physiological TE construction of other tissues and helps to reverse fibrosis pathologies in general.

Identification of miRNAs associated with the mechanical response of hepatic stellate cells by miRNA microarray analysis

It has been suggested that hepatic stellate cells (HSCs) could be used in the regulation of liver microcirculation and portal hypertension. The effects of tensile strain on the microRNA (miRNA) profile of HSCs are largely unknown. In this study, we aimed to explore the changes of miRNA expression in tensile strain-treated HSCs. The purity and activation of HSCs were determined by immunofluorescence staining with antibody against desmin and a-SMA, respectively. miRNA profile analysis was performed on HSCs with and without tensile strain treatment (n=3) using microarray analysis. We identified 6 significantly differentially expressed miRNAs (DEMs), including 1 downregulated (rno-miR-125b-2-3p) and 5 upregulated (rno-miR-1224, rho-miR-188-5p, rho-miR-211-3p, rho-miR-3584-5p and rho-miR-466b-5p), which were validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) experiments. Further analysis of the DEMs revealed that many important biological processes and signal pathways were triggered in tensile strain-treated HSCs. These include the signal transduction mechanisms associated with protein binding, apoptosis, proliferation, and the FoxO and Wnt signaling pathways. In conclusion, this study presents the specific DEMs in tensile strain-treated HSCs. Our study provide novel miRNA-based information that may enhance our understanding of the pathophysiological processes leading to portal hypertension.