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

Association of CXCR4 gene expression and promoter methylation with chronic hepatitis B-related fibrosis/cirrhosis

OBJECTIVE

Chronic hepatitis B (CHB) virus infection remains a major public health concern. In this study, the diagnostic capability of C-X-C chemokine receptor type 4 promoter methylation in patients with CHB-associated liver fibrosis/cirrhosis was evaluated.

METHODS

Two hundred participants were recruited, including 25 healthy controls (HCs), 60 patients with CHB and 115 patients with hepatitis B virus (HBV)-related liver fibrosis/LC. Researchers monitored the methylation and messenger ribonucleic acid (mRNA) levels of C-X-C chemokine receptor type 4 (CXCR4) in peripheral blood mononuclear cells (PBMCs). In addition, we utilized single cell sequencing to analyze the cell types highly expressing CXCR4 in HBV-related liver fibrosis/LC.

RESULTS

HBV-related fibrosis/cirrhosis patients exhibited a significant elevation in the expression level of CXCR4 mRNA in PBMCs compared to CHB ones. The CXCR4 promoter showed a significantly lower methylation level in patients with CHB-related fibrosis/cirrhosis than in patients with CHB. Additionally, the diagnostic area under the area under the curve (AUC) of methylation of the CXCR4 promoter for CHB -related liver fibrosis/LC exceeded liver stiffness measurement (LSM), aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis-4 score (FIB-4). Furthermore, single-cell analysis demonstrated that CXCR4 expression is closely associated with Natural Killer cells(NK cells), T lymphocytes (T cells), and monocytes.

CONCLUSION

The low methylation of the CXCR4 promoter holds promise as a non-invasive biomarker for detecting CHB-associated liver fibrosis/LC.

H3K18 lactylation accelerates liver fibrosis progression through facilitating SOX9 transcription

Liver fibrosis is a significant health concern globally due to its association with severe liver conditions like cirrhosis and liver cancer. Histone lactylation has been implicated in the progression of hepatic fibrosis, but its specific role in liver fibrosis, particularly regarding H3K18 lactylation, remained unclear. To investigate this, we established in vivo and in vitro models of liver fibrosis using carbon tetrachloride (CCl4) injection in rats and stimulation of hepatic stellate cells (HSCs) with TGF-β1, respectively. We found that histone lactylation, particularly H3K18 lactylation, was upregulated in both CCl4-induced rats and TGF-β1-activated HSCs, indicating its potential involvement in liver fibrosis. Further experiments revealed that lactate dehydrogenase A (LDHA) knockdown inhibited H3K18 lactylation and had a beneficial effect on liver fibrosis by suppressing HSC proliferation, migration, and extracellular matrix (ECM) deposition. This suggests that H3K18 lactylation promotes liver fibrosis progression. Chromatin immunoprecipitation (ChIP) and luciferase reporter assays demonstrated that H3K18 lactylation facilitated the transcription of SOX9, a transcription factor associated with fibrosis. Importantly, overexpression of SOX9 counteracted the effects of LDHA silencing on activated HSCs, indicating that SOX9 is downstream of H3K18 lactylation in promoting liver fibrosis. In summary, this study uncovers a novel mechanism by which H3K18 lactylation contributes to liver fibrosis by activating SOX9 transcription. This finding opens avenues for exploring new therapeutic strategies for hepatic fibrosis targeting histone lactylation pathways.

Roles and therapeutic targeting of dendritic cells in liver fibrosis

Liver fibrosis is a common pathological condition marked by excessive accumulation of extracellular matrix proteins, resulting in irreversible cirrhosis and cancer. Dendritic cells (DCs) act as the crucial component of hepatic immunity and are believed to affect fibrosis by regulating the proliferation and differentiation of hepatic stellate cells (HSCs), a key mediator of fibrogenesis, and by interplaying with immune cells in the liver. This review concisely describes the process of fibrogenesis, and the phenotypic and functional characteristics of DCs in the liver. Besides, it focuses on the interaction between DCs and HSCs, T cells, and natural killer (NK) cells, as well as the dual roles of DCs in liver fibrosis, for the sake of exploring the potential of targeting DCs as a therapeutic strategy for the disease.

UCHL1-dependent control of hypoxia-inducible factor transcriptional activity during liver fibrosis

Liver fibrosis is the excessive accumulation of extracellular matrix proteins that occurs in most types of chronic liver disease. At the cellular level, liver fibrosis is associated with the activation of hepatic stellate cells (HSCs) which transdifferentiate into a myofibroblast-like phenotype that is contractile, proliferative and profibrogenic. HSC transdifferentiation induces genome-wide changes in gene expression that enable the cell to adopt its profibrogenic functions. We have previously identified that the deubiquitinase ubiquitin C-terminal hydrolase 1 (UCHL1) is highly induced following HSC activation; however, the cellular targets of its deubiquitinating activity are poorly defined. Here, we describe a role for UCHL1 in regulating the levels and activity of hypoxia-inducible factor 1 (HIF1), an oxygen-sensitive transcription factor, during HSC activation and liver fibrosis. HIF1 is elevated during HSC activation and promotes the expression of profibrotic mediator HIF target genes. Increased HIF1α expression correlated with induction of UCHL1 mRNA and protein with HSC activation. Genetic deletion or chemical inhibition of UCHL1 impaired HIF activity through reduction of HIF1α levels. Furthermore, our mechanistic studies have shown that UCHL1 elevates HIF activity through specific cleavage of degradative ubiquitin chains, elevates levels of pro-fibrotic gene expression and increases proliferation rates. As we also show that UCHL1 inhibition blunts fibrogenesis in a pre-clinical 3D human liver slice model of fibrosis, these results demonstrate how small molecule inhibitors of DUBs can exert therapeutic effects through modulation of HIF transcription factors in liver disease. Furthermore, inhibition of HIF activity using UCHL1 inhibitors may represent a therapeutic opportunity with other HIF-related pathologies.

HDAC9 as a Privileged Target: Reviewing its Role in Different Diseases and Structure-activity Relationships (SARs) of its Inhibitors

HDAC9 is a histone deacetylase enzyme belonging to the class IIa of HDACs which catalyses histone deacetylation. HDAC9 inhibit cell proliferation by repairing DNA, arresting the cell cycle, inducing apoptosis, and altering genetic expression. HDAC9 plays a significant part in human physiological system and are involved in various type of diseases like cancer, diabetes, atherosclerosis and CVD, autoimmune response, inflammatory disease, osteoporosis and liver fibrosis. This review discusses the role of HDAC9 in different diseases and structure-activity relationships (SARs) of various hydroxamate and non-hydroxamate-based inhibitors. SAR of compounds containing several scaffolds have been discussed in detail. Moreover, structural requirements regarding the various components of HDAC9 inhibitor (cap group, linker and zinc-binding group) has been highlighted in this review. Though, HDAC9 is a promising target for the treatment of a number of diseases including cancer, a very few research are available. Thus, this review may provide useful information for designing novel HDAC9 inhibitors to fight against different diseases in the future.

Serum α-SMA is a potential noninvasive biomarker of liver fibrosis

The severity of fibrosis is central to the therapeutic course for patients with chronic liver disease; therefore, early detection of liver fibrosis is critical for timely therapeutic interventions. Liver biopsy is the gold standard for the diagnosis of liver fibrosis; however, it is contraindicated in several pathological conditions. Activated hepatic stellate cells (HSCs) are the main cells for fibrotic tissue synthesis, such as that of alpha-smooth muscle actin (α-SMA). This study aimed to determine whether serum α-SMA levels are a suitable noninvasive, sensitive, and reliable liver fibrosis marker. Fibrosis was induced in male Wistar rats via chronic CCl4 administration. Fibrosis was determined in the liver tissues by quantifying the hydroxyproline content and visualized using Masson's trichrome staining. Rats chronically administered CCl4 exhibited a progressive increment in the hepatic collagen content, as well as both hepatic and serum α-SMA levels in a time-dependent manner. Moreover, serum levels of α-SMA significantly correlated with hepatic α-SMA levels (p ≤ 0.001), as well as with the severity of liver fibrosis (p ≤ 0.001). These findings suggest that increased levels of serum α-SMA can be considered a potential reliable and noninvasive biomarker for early liver fibrosis.

27-Hydroxycholesterol induces liver fibrosis via down-regulation of trimethylation of histone H3 at lysine 27 by activating oxidative stress; effect of nutrient interventions

BACKGROUND

Chronic liver injury caused by activation of hepatic stellate cells (HSCs) is a key event in the development of liver fibrosis (LF). A high-cholesterol diet can prompt accumulation of free cholesterol in HSCs, which promotes HSC activation and progression of LF.

OBJECTIVE

27-Hydroxycholesterol (27HC) is the most abundant cholesterol metabolite. Here, we investigated whether the HSC activation and LF induced by high cholesterol is caused by its metabolite 27HC, and whether TGFβ classical signaling were involved in these processes.

METHODS

In vitro, LX2 and HSC-T6 cells were used to explore the effects of 27HC on activation of HSCs, while LSECs were used to observe the effects of 27HC on capillarization. In vivo, zebrafish were used to assess the effect of 27HC on LF.

RESULTS

The cholesterol metabolite 27HC promoted the proliferation of HSCs and up-regulated expression of COL-1 and α-SMA as well as CTGF and TIMP1. Also, 27HC up-regulated expression of Smad2/3 and phosphorylated Smad2/3 in HSCs. Furthermore, 27HC-induced up-regulation of COL-1, α-SMA, CTGF, and TIMP1 protein levels was inhibited by Smad2/3 knockout. In addition, 27HC down-regulated H3K27me3 by inhibition of EZH2 and promotion of UTX and JMJD3 expression via the TGFβ signaling, thereby inducing activation of HSCs. Notably, 27HC significantly aggravated the pathological damage induced by DEN, and induced deposition of collagen fibers in zebrafish liver. Folic acid (FA) and resveratrol (RES) both reduced 27HC-induced production of reactive oxygen species (ROS) and inhibited the effects of TGFβ signaling on EZH2, UTX, and JMJD3, thereby increasing H3K27me3, and finally jointly inhibiting LF.

CONCLUSION

Cholesterol is metabolized to 27HC, which mediates activation of HSCs and onset of LF. Reduced expression of H3k27me3 by TGFβ signaling is crucial to 27HC-induced LF. FA and RES ameliorated activation of HSCs and LF by reducing 27HC-induced production of ROS and regulating of H3K27me3.

Targeting Interleukin-17 as a Novel Treatment Option for Fibrotic Diseases

Fibrosis is the end result of persistent inflammatory responses induced by a variety of stimuli, including chronic infections, autoimmune reactions, and tissue injury. Fibrotic diseases affect all vital organs and are characterized by a high rate of morbidity and mortality in the developed world. Until recently, there were no approved antifibrotic therapies. In recent years, high levels of interleukin-17 (IL-17) have been associated with chronic inflammatory diseases with fibrotic complications that culminate in organ failure. In this review, we provide an update on the role of IL-17 in fibrotic diseases, with particular attention to the most recent lines of research in the therapeutic field represented by the epigenetic mechanisms that control IL-17 levels in fibrosis. A better knowledge of the IL-17 signaling pathway implications in fibrosis could design new strategies for therapeutic benefits.

Extracellular matrix turnover: phytochemicals target and modulate the dual role of matrix metalloproteinases (MMPs) in liver fibrosis

Extracellular matrix (ECM) resolution by matrix metalloproteinases (MMPs) is a well-documented mechanism. MMPs play a dual and complex role in modulating ECM degradation at different stages of liver fibrosis, depending on the timing and levels of their expression. Increased MMP-1 combats disease progression by cleaving the fibrillar ECM. Activated hepatic stellate cells (HSCs) increase expression of MMP-2, -9, and -13 in different chemicals-induced animal models, which may alleviate or worsen disease progression based on animal models and the stage of liver fibrosis. In the early stage, elevated expression of certain MMPs may damage surrounding tissue and activate HSCs, promoting fibrosis progression. At the later stage, downregulation of MMPs can facilitate ECM accumulation and disease progression. A number of phytochemicals modulate MMP activity and ECM turnover, alleviating disease progression. However, the effects of phytochemicals on the expression of different MMPs are variable and may depend on the disease models and stage, and the dosage, timing and duration of phytochemicals used in each study. Here, we review the most recent advances in the role of MMPs in the effects of phytochemicals on liver fibrogenesis, which indicates that further studies are warranted to confirm and define the potential clinical efficacy of these phytochemicals.

Comprehensive analysis of epigenetic and epitranscriptomic genes' expression in human NAFLD

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial condition with a complex etiology. Its incidence is increasing globally in parallel with the obesity epidemic, and it is now considered the most common liver disease in Western countries. The precise mechanisms underlying the development and progression of NAFLD are complex and still poorly understood. The dysregulation of epigenetic and epitranscriptomic mechanisms is increasingly recognized to play pathogenic roles in multiple conditions, including chronic liver diseases. Here, we have performed a comprehensive analysis of the expression of epigenetic and epitranscriptomic genes in a total of 903 liver tissue samples corresponding to patients with normal liver, obese patients, and patients with non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH), advancing stages in NAFLD progression. We integrated ten transcriptomic datasets in an unbiased manner, enabling their robust analysis and comparison. We describe the complete landscape of epigenetic and epitranscriptomic genes' expression along the course of the disease. We identify signatures of genes significantly dysregulated in association with disease progression, particularly with liver fibrosis development. Most of these epigenetic and epitranscriptomic effectors have not been previously described in human NAFLD, and their altered expression may have pathogenic implications. We also performed a comprehensive analysis of the expression of enzymes involved in the metabolism of the substrates and cofactors of epigenetic and epitranscriptomic effectors. This study provides novel information on NAFLD pathogenesis and may also guide the identification of drug targets to treat this condition and its progression towards hepatocellular carcinoma.

Effect of distinct ECM microenvironments on the genome-wide chromatin accessibility and gene expression responses of hepatic stellate cells

Hepatic stellate cells (HSCs) are one of the primary drivers of liver fibrosis in non-alcoholic fatty liver disease. Although HSC activation in liver disease is associated with changes in extracellular matrix (ECM) deposition and remodeling, it remains unclear how ECM regulates the phenotypic state transitions of HSCs. Using high-throughput cellular microarrays, coupled with genome-wide ATAC and RNA sequencing within engineered ECM microenvironments, we investigated the effect of ECM and substrate stiffness on chromatin accessibility and resulting gene expression in activated primary human HSCs. Cell microarrays demonstrated the cooperative effects of stiffness and ECM composition on H3K4 and H3K9 methylation/acetylation. ATAC sequencing revealed higher chromatin accessibility in HSCs on 1kPa compared to 25kPa substrates for all ECM conditions. Gene set enrichment analysis using RNA sequencing data of HSCs in defined ECM microenvironments demonstrated higher enrichment of NAFLD and fibrosis-related genes in pre-activated HSCs on 1kPa relative to 25kPa. Overall, these findings are indicative of a microenvironmental adaptation response in HSCs, and the acquisition of a persistent activation state. Combined ATAC/RNA sequencing analyses enabled identification of candidate regulatory factors, including HSD11B1 and CEBPb. siRNA-mediated knockdown of HSD11b1 and CEBPb demonstrated microenvironmental controlled reduction in fibrogenic markers in HSCs. STATEMENT OF SIGNIFICANCE: Hepatic stellate cells (HSCs) are one of the primary drivers of liver fibrosis in non-alcoholic fatty liver disease. Although HSC activation in liver disease is associated with changes in extracellular matrix (ECM) deposition and remodeling, it remains unclear how ECM regulates the phenotypic state transitions of HSCs. Using high-throughput cellular microarrays, coupled with genome-wide ATAC and RNA sequencing within engineered ECM microenvironments, we investigated the effect of ECM and substrate stiffness on chromatin accessibility and resulting gene expression in activated primary human HSCs. Overall, these findings were indicative of a microenvironmental adaptation response in HSCs, and the acquisition of a persistent activation state. Combined ATAC/RNA sequencing analyses enabled identification of candidate regulatory factors, including HSD11B1 and CEBPb. siRNA-mediated knockdown of HSD11b1 and CEBPb demonstrated microenvironmental controlled reduction in fibrogenic markers in HSCs.

Hexokinase 2-mediated gene expression via histone lactylation is required for hepatic stellate cell activation and liver fibrosis

Lactate was implicated in the activation of hepatic stellate cells (HSCs). However, the mechanism by which lactate exerts its effect remains elusive. Using RNA-seq and CUT&Tag chromatin profiling, we found that induction of hexokinase 2 (HK2) expression in activated HSCs is required for induced gene expression by histone lactylation but not histone acetylation. Inhibiting histone lactylation by Hk2 deletion or pharmacological inhibition of lactate production diminishes HSC activation, whereas exogenous lactate but not acetate supplementation rescues the activation phenotype. Thus, lactate produced by activated HSCs determines the HSC fate via histone lactylation. We found that histone acetylation competes with histone lactylation, which could explain why class I HDAC (histone deacetylase) inhibitors impede HSC activation. Finally, HSC-specific or systemic deletion of HK2 inhibits HSC activation and liver fibrosis in vivo. Therefore, we provide evidence that HK2 may be an effective therapeutic target for liver fibrosis.

Reconstruction of bone marrow microenvironment for expansion of hematopoietic stem cells by a histone deacetylase inhibitor

Ex vivo expansion of hematopoietic stem cells (HSCs) is an approach for overcoming cell insufficiency for umbilical cord blood transplantation. It was suggested that in common ex vivo cultures, the stemness specificity of HSCs is rapidly reducing due to DNA hypermethylation. Here, Nicotinamide (NAM), a DNA methyltransferase and histone deacetylase inhibitor, is used with a bioengineered Bone Marrow-like niche (BLN) for HSC ex vivo expansion. The CFSE cell proliferation assay was used for tracking HSCs division. qRT-PCR was conducted to assay the HOXB4 mRNA expression levels. The morphology of BLN-cultured cells was analyzed using scanning electron microscopy (SEM). NAM boosted the induction of HSC proliferation in the BLN group compared to the control group. In addition, the ability of HSCs to colonize was more significant in the BLN group than in the control group. Our data suggest that the presence of NAM in bioengineered niches promotes HSC proliferation. The presented approach showed that small molecules could be used in the clinical setting to overcome the limited number of CD34+ cells in cord blood units.

Unraveling the Emerging Niche Role of Hepatic Stellate Cell-derived Exosomes in Liver Diseases

Hepatic stellate cells (HSCs) play an essential role in various liver diseases, and exosomes are critical mediators of intercellular communication in local and distant microenvironments. Cellular crosstalk between HSCs and surrounding multiple tissue-resident cells promotes or inhibits the activation of HSCs. Substantial evidence has revealed that HSC-derived exosomes are involved in the occurrence and development of liver diseases through the regulation of retinoid metabolism, lipid metabolism, glucose metabolism, protein metabolism, and mitochondrial metabolism. HSC-derived exosomes are underpinned by vehicle molecules, such as mRNAs and microRNAs, that function in, and significantly affect, the processes of various liver diseases, such as acute liver injury, alcoholic liver disease, nonalcoholic fatty liver disease, viral hepatitis, fibrosis, and cancer. As such, numerous exosomes derived from HSCs or HSC-associated exosomes have attracted attention because of their biological roles and translational applications as potential targets for therapeutic targets. Herein, we review the pathophysiological and metabolic processes associated with HSC-derived exosomes, their roles in various liver diseases and their potential clinical application.

TET3 as a non-invasive screening tool for the detection of fibrosis in patients with chronic liver disease

Ten-eleven translocation protein 3 (TET3) is one of the key enzymes in DNA demethylation which can be expressed in liver tissues. However, the clinical value of TET3 for diagnosis and treatment of chronic liver disease have not been reported previously. We investigated the diagnostic accuracy of serum TET3 as a non-invasive screening tool for liver fibrosis. 212 patients with chronic liver disease from were enrolled in this study. Enzyme-linked immunosorbent assay was used to measure the serum levels of TET3. Receiver operating characteristics (ROC) were determined to examine the diagnostic accuracy of TET3 and combination model for diagnosis fibrosis. Serum TET3 level in fibrosis cases was significantly higher than that in non-fibrosis and controls, respectively. The areas under the ROC curve of the TET3 and fibrosis-4 index for liver fibrosis were 0.863 and 0.813, and 0.916 and 0.957 for liver cirrhosis. The combination of TET3 and fibrosis-4 index had a highly promising positive predictive value for detecting liver fibrosis and cirrhosis different stages of (93.5% and 100%) as compared with each diagnostic tool alone. TET3 is related to the development of liver fibrosis and cirrhosis. The TET3-fibrosis-4 model enhances discriminatory power and represents a promising non-invasive tool for the diagnosis and screening of liver fibrosis.

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.

Minichromosome maintenance gene family: potential therapeutic targets and prognostic biomarkers for lung squamous cell carcinoma

The minichromosome maintenance (MCM) gene family comprises of ten members with key roles in eukaryotic DNA replication and are associated with the occurrence and progression of many tumors. However, whether the MCM family contributes to lung squamous cell carcinoma (LUSC) is unclear. In this study, we performed bioinformatic analysis to identify the roles of MCM genes in patients with LUSC. We also evaluated their differential gene expression, prognostic correlation, DNA methylation, functional enrichment of genetic alterations, and immunomodulation. According to the Tumor Immune Estimation Resource database, the expression of MCM2-10 mRNA was elevated in LUSC tissues. According to the Gene Expression Profiling Interactive Analysis database, MCM2-8 and MCM10 were considerably upregulated in LUSC tissues, and protein levels of all MCMs were increased in LUSC tissues. In addition, among the MCM family members, the expression of MCM3 and MCM7 showed the strongest correlation with the prognoses of patients with LUSC. To clarify the role and mechanisms of the MCM family, Kyoto Encyclopedia of Genes and Genomes and Gene Ontology enrichment studies were performed. We detected a significant correlation between the expression patterns of MCM family members and infiltrating immune cells. In conclusion, our results improve the understanding of the aberrant expression of MCM family members in LUSC. These findings demonstrate the potential of the MCM family as therapeutic targets and biomarkers for the diagnosis and prognosis of LUSC.

RNA m6A modification in liver biology and its implication in hepatic diseases and carcinogenesis

N6-methyladenosine (m6A) is the most prevalent internal modification in eukaryotic RNAs. This modification is regulated by three different factors (writers, erasers, and readers) and affects multiple aspects of RNA metabolism, including RNA splicing, nuclear export, translation, stability and decay. The m6A-mediated modification plays important roles in posttranscriptional regulation of gene expression and mediates a variety of cellular and biological processes. Accordingly, deregulation in m6A modification is closely related to the occurrence and development of human diseases. The liver is the largest digestive and metabolic organ in human and recent studies have shown that m6A modification is importantly implicated in liver cellular and physiological functions and in the pathogenesis of hepatic diseases and cancers. In the current review, we summarize the functions of m6A in RNA metabolism and its roles in liver cell biology and discuss its implication in hepatic diseases and carcinogenesis.

Prognostic Value, Immune Signature, and Molecular Mechanisms of the PHLDA Family in Pancreatic Adenocarcinoma

Background: Increasing evidence supports the belief that the pleckstrin homology domain family A (PHLDA) family is associated with the development of a variety of cancers. However, the function of the PHLDA family members in PAAD is still unclear. Methods: Comprehensive bioinformatic analyses using R (version 3.6.3), Cytoscape (version 3.9.1), UALCAN, etc., were performed to study the clinicopathological characteristics, prognostic value, immune features, and functional mechanisms of the PHLDA family members in PAAD. Results: The PHLDA family members showed significantly elevated expression in PAAD compared with paracancerous or normal tissues. Their high expression or amplification were significantly correlated with worse clinicopathological characteristics and prognosis in PAAD patients. In addition, the role of the PHLDA family members in the immune regulation is diverse and complex. Mechanistically, TP53 mutations were significantly associated with the promoter methylation and expression levels of the PHLDA family members, which were activated in multiple oncogenic pathways, including the EMT, RAS/MAPK, and TSC/mTOR pathways. Moreover, we found that their expression levels were significantly correlated with the sensitivity of multiple traditional chemotherapeutic drugs and novel targeted MEK1/2 inhibitors. Conclusion: The PHLDA family members play an oncogenic role in the development of PAAD and might serve as new biomarkers or therapeutic targets.

CircTUBD1 Regulates Radiation-induced Liver Fibrosis Response via a circTUBD1/micro-203a-3p/Smad3 Positive Feedback Loop

BACKGROUND AND AIMS

Radiation-induced liver fibrosis (RILF), delayed damage to the liver (post-irradiation) remains a major challenge for the radiotherapy of liver malignancies. This study investigated the potential function and mechanism of circTUBD1 in the development of RILF.

METHODS

By using a dual luciferase assay, RNA pull-down assays, RNA sequencing, chromatin immunoprecipitation (known as ChIP) assays, and a series of gain- or loss-of-function experiments, it was found that circTUBD1 regulated the activation and fibrosis response of LX-2 cells induced by irradiation via a circTUBD1/micro-203a-3p/Smad3 positive feedback loop in a 3D system.

RESULTS

Knockdown of circTUBD1 not only reduced the expression of α-SMA, as a marker of LX-2 cell activation, but also significantly decreased the levels of hepatic fibrosis molecules, collagen type I alpha 1 (COL1A1), collagen type III alpha 1 (COL3A1), and connective tissue growth factor (CTGF) in a three-dimensional (3D) culture system and RILF model in vivo. Notably, knockdown of circTUBD1 alleviated early liver fibrosis induced by irradiation in mice models.

CONCLUSIONS

This study is the first to reveal the mechanism and role of circTUBD1 in RILF via a circTUBD1/micro-203a-3p/Smad3 feedback loop, which provides a novel therapeutic strategy for relieving the progression of RILF.

Traditional Chinese medicine: An important source for discovering candidate agents against hepatic fibrosis

Hepatic fibrosis (HF) refers to the pathophysiological process of connective tissue dysplasia in the liver caused by various pathogenic factors. Nowadays, HF is becoming a severe threat to the health of human being. However, the drugs available for treating HF are limited. Currently, increasing natural agents derived from traditional Chinese medicines (TCMs) have been found to be beneficial for HF. A systemic literature search was conducted from PubMed, GeenMedical, Sci-Hub, CNKI, Google Scholar and Baidu Scholar, with the keywords of “traditional Chinese medicine,” “herbal medicine,” “natural agents,” “liver diseases,” and “hepatic fibrosis.” So far, more than 76 natural monomers have been isolated and identified from the TCMs with inhibitory effect on HF, including alkaloids, flavones, quinones, terpenoids, saponins, phenylpropanoids, and polysaccharides, etc. The anti-hepatic fibrosis effects of these compounds include hepatoprotection, inhibition of hepatic stellate cells (HSC) activation, regulation of extracellular matrix (ECM) synthesis & secretion, regulation of autophagy, and antioxidant & anti-inflammation, etc. Natural compounds and extracts from TCMs are promising agents for the prevention and treatment of HF, and this review would be of great significance to development of novel drugs for treating HF.

Multifunctional roles and pharmacological potential of β-sitosterol: Emerging evidence toward clinical applications

Currently, available therapeutic medications are both costly as well as not entirely promising in terms of potency. So, new candidates from natural resources are of research interest to find new alternative therapeutics. A well-known combination is a β-sitosterol, a plant-derived nutrient with anticancer properties against breast, prostate, colon, lung, stomach, and leukemia. Studies have shown that β-sitosterol interferes with multiple cell signaling pathways, including cell cycle, apoptosis, proliferation, survival, invasion, angiogenesis, metastasis, anti-inflammatory, anticancer, hepatoprotective, antioxidant, cardioprotective, and antidiabetic effects have been discovered during pharmacological screening without significant toxicity. The pharmacokinetic profile of β-sitosterol has also been extensively investigated. However, a comprehensive review of the pharmacology, phytochemistry and analytical methods of β-sitosterol is desired. Because β-sitosterol is a significant component of most plant materials, humans use it for various reasons, and numerous β-sitosterol-containing products have been commercialized. To offset the low efficacy of β-sitosterol, designing β-sitosterol delivery for "cancer cell-specific" therapy holds great potential. Delivery of β-sitosterol via liposomes is a demonstration that has shown great promise. But further research has not progressed on the drug delivery of β-sitosterol or how it can enhance β-sitosterol mediated anti-inflammatory activity, thus making β-sitosterol an orphan nutraceutical. Therefore, extensive research on β-sitosterol as an anticancer nutraceutical is recommended.

Tibetan Medicine Shi-Wei-Gan-Ning-San Alleviates Carbon Tetrachloride-Induced Chronic Liver Injury by Inhibiting TGF-β1 in Wistar Rats

Background. Shi-Wei-Gan-Ning-San (SWGNS) is a classic Tibetan prescription, which has obvious clinical effects in the treatment of viral hepatitis, fatty liver, liver fibrosis, liver cirrhosis, liver cancer, and other liver injuries. However, animal studies and mechanism studies are still lacking. This study aimed to investigate its hepatoprotective efficacy and pharmacological mechanism in animal experiments. Methods. Chronic liver injury was induced by oral administration of carbon tetrachloride (CCl4) in Wistar rats for 13 weeks. SWGNS was administered orally to rats at doses of 235, 705, and 1410 mg/kg for 13 weeks. Blood samples were collected for biochemical, ELISA, and radioimmunoassay. Livers were harvested for H&E and immunohistochemical staining. The major constituents of SWGNS were analyzed by HPLC. In vitro experiments were used to explore the protective effect of Crocin on BRL-3A in the environment of H2O2. Results. SWGNS reversed weight loss is induced by CCl4. Serum assays showed that SWGNS reduced CCl4-induced alanine aminotransferase, aspartate aminotransferase, total bilirubin, and γ-glutamyltransferase levels and increased the total protein and albumin levels. Histopathological evaluation showed that SWGNS alleviated hepatic steatosis, fibrosis, and inflammation. Furthermore, SWNGS reduced CCl4-induced elevations of TGF-β1, hyaluronic acid, laminin, and collagen IV in serum and reduced the high expression of α-SMA in tissues. Moreover, Crocin I and II are the main components of SWGNS. Crocin attenuated the damaging effects of H2O2 on BRL-3A. Conclusions. In conclusion, SWGNS alleviated CCl4-induced chronic liver injury by inhibiting the TGF-β1 pathway. This plays an important role in promoting traditional Tibetan medicine in clinical practice.

Intercellular crosstalk of liver sinusoidal endothelial cells in liver fibrosis, cirrhosis and hepatocellular carcinoma

Intercellular crosstalk among various liver cells plays an important role in liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Capillarization of liver sinusoidal endothelial cells (LSECs) precedes fibrosis and accumulating evidence suggests that the crosstalk between LSECs and other liver cells is critical in the development and progression of liver fibrosis. LSECs dysfunction, a key event in the progression from fibrosis to cirrhosis, and subsequently obstruction of hepatic sinuses and increased intrahepatic vascular resistance (IHVR) contribute to development of portal hypertension (PHT) and cirrhosis. More importantly, immunosuppressive tumor microenvironment (TME), which is closely related to the crosstalk between LSECs and immune liver cells like CD8+ T cells, promotes advances tumorigenesis, especially HCC. However, the connections within the crosstalk between LSECs and other liver cells during the progression from liver fibrosis to cirrhosis to HCC have yet to be discussed. In this review, we first summarize the current knowledge of how different crosstalk between LSECs and other liver cells, including hepatocytes, hepatic stellate cells (HSCs), macrophoges, immune cells in liver and extra cellular matrix (ECM) contribute to the physiological function and the progrssion from liver fibrosis to cirrhosis, or even to HCC. Then we examine current treatment strategies for LSECs crosstalk in liver fibrosis, cirrhosis and HCC.

miR-654-5p Contributes to the Activation and Proliferation of Hepatic Stellate Cells by Targeting RXRα

Liver fibrosis (LF) is a major disease that threatens human health. Hepatic stellate cells (HSCs) contribute directly to LF via extracellular matrix (ECM) secretion. Moreover, RXRα is an important nuclear receptor that plays a key regulatory role in HSC activation. Meanwhile, microRNAs (miRNAs) have been identified as significant regulators of LF development. In particular, miR-654-5p is involved in cellular migration and proliferation, and via bioinformatics analysis, has been identified as a potential factor that targets RXRα in humans and in mice. However, the precise relationship between miR-654-5p and RXRα in the context of LF, remains unknown and is the primary focus of the current study. To establish in vitro activated cell model human primary HSCs were cultured in vitro and LX-2 cells were stimulated with recombinant human TGF-β1. mRNA and protein levels of RXRα, miR-654-5p and fibrogenic genes were compared in quiescent and activated HSCs. Moreover, after transfected with miR-654-5p mimics, the expression changes of above related genes in LX-2 cells were estimated. Meanwhile, cell proliferation and apoptosis were detected in miR-654-5p overexpressed LX-2 cells. Simultaneously, the targeted binding between miR-654-5p and RXRα was verified in LX-2 cells. Carbon tetrachloride (CCl₄)-induced mouse model with liver fibrosis was use to research the role of the miR-654-5p in vitro. Our results show that miR-654-5p expression levels increased in activated human HSCs and TGFβ-treated LX-2 cells. Moreover, miR-654-5p mimics markedly promoted LX-2 cell proliferation while inhibiting their apoptosis. Accordingly, the expression levels of RXRα are decreased in activated HSCs and LX-2 cells. Additionally, dual-luciferase reporter assay results reveal direct targeting of RXRα by miR-654-5p. Similarly, in vivo miR-654-5p overexpression aggravates LF in mice that are intraperitoneally injected with CCl₄. Taken together, our findings elucidated a novel molecular mechanism with potential use for treatment of LF.

Crosstalk Between Inflammatory Signaling and Methylation in Cancer

Inflammation is an intricate immune response against infection and tissue damage. While the initial immune response is important for preventing tumorigenesis, chronic inflammation is implicated in cancer pathogenesis. It has been linked to various stages of tumor development including transformation, proliferation, angiogenesis, and metastasis. Immune cells, through the production of inflammatory mediators such as cytokines, chemokines, transforming growth factors, and adhesion molecules contribute to the survival, growth, and progression of the tumor in its microenvironment. The aberrant expression and secretion of pro-inflammatory and growth factors by the tumor cells result in the recruitment of immune cells, thus creating a mutual crosstalk. The reciprocal signaling between the tumor cells and the immune cells creates and maintains a successful tumor niche. Many inflammatory factors are regulated by epigenetic mechanisms including DNA methylation and histone modifications. In particular, DNA and histone methylation are crucial forms of transcriptional regulation and aberrant methylation has been associated with deregulated gene expression in oncogenesis. Such deregulations have been reported in both solid tumors and hematological malignancies. With technological advancements to study genome-wide epigenetic landscapes, it is now possible to identify molecular mechanisms underlying altered inflammatory profiles in cancer. In this review, we discuss the role of DNA and histone methylation in regulation of inflammatory pathways in human cancers and review the merits and challenges of targeting inflammatory mediators as well as epigenetic regulators in cancer.

MyD88 in Macrophages Enhances Liver Fibrosis by Activation of NLRP3 Inflammasome in HSCs

Chronic liver disease mediated by the activation of hepatic stellate cells (HSCs) leads to liver fibrosis. The signal adaptor MyD88 of Toll-like receptor (TLR) signaling is involved during the progression of liver fibrosis. However, the specific role of MyD88 in myeloid cells in liver fibrosis has not been thoroughly investigated. In this study, we used a carbon tetrachloride (CCl₄)-induced mouse fibrosis model in which MyD88 was selectively depleted in myeloid cells. MyD88 deficiency in myeloid cells attenuated liver fibrosis in mice and decreased inflammatory cell infiltration. Furthermore, deficiency of MyD88 in macrophages inhibits the secretion of CXC motif chemokine 2 (CXCL2), which restrains the activation of HSCs characterized by NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome activation. Moreover, targeting CXCL2 by CXCR2 inhibitors attenuated the activation of HSCs and reduced liver fibrosis. Thus, MyD88 may represent a potential candidate target for the prevention and treatment of liver fibrosis.

Liver Fibrosis and MAFLD: From Molecular Aspects to Novel Pharmacological Strategies

Metabolic-associated fatty liver disease (MAFLD) is a new disease definition, and this nomenclature MAFLD was proposed to renovate its former name, non-alcoholic fatty liver disease (NAFLD). MAFLD/NAFLD have shared and predominate causes from nutrition overload to persistent liver damage and eventually lead to the development of liver fibrosis and cirrhosis. Unfortunately, there is an absence of effective treatments to reverse MAFLD/NAFLD-associated fibrosis. Due to the significant burden of MAFLD/NAFLD and its complications, there are active investigations on the development of novel targets and pharmacotherapeutics for treating this disease. In this review, we cover recent discoveries in new targets and molecules for antifibrotic treatment, which target pathways intertwined with the fibrogenesis process, including lipid metabolism, inflammation, cell apoptosis, oxidative stress, and extracellular matrix formation. Although marked advances have been made in the development of antifibrotic therapeutics, none of the treatments have achieved the endpoints evaluated by liver biopsy or without significant side effects in a large-scale trial. In addition to the discovery of new druggable targets and pharmacotherapeutics, personalized medication, and combinatorial therapies targeting multiple profibrotic pathways could be promising in achieving successful antifibrotic interventions in patients with MAFLD/NAFLD.

Dual inhibition of reactive oxygen species and spleen tyrosine kinase as a therapeutic strategy in liver fibrosis

Hepatic stellate cells (HSCs) play key roles in liver fibrosis (LF) and hepatocellular carcinoma (HCC). We previously reported that spleen tyrosine kinase (SYK) is critical for HSCs activation, however, the mechanisms are insufficiently understood. In the present study, we found that SYK facilitated autophagy to promote HSCs activation by enhancing reactive oxygen species (ROS) generation. However, SYK inhibitor GS-9973 could efficiently reduce HSCs ROS generation in vitro but not in vivo. Mechanistically, hepatocytes (HCs) would release ROS outside and then diffuse into HSCs to promote autophagy and activation in vitro in the context of inflammation. We then further examined the ROS contents in liver sections and primary liver cells of carbon tetrachloride (CCl4) induced mice treated with or without different doses of Silybin, a natural compound characterized by a well-established antioxidant and hepatoprotective properties, and found that ROS intensities in both liver sections and their deprived primary cells were efficiently inhibited in a dose-dependent fashion. Lastly, we evaluated the rational combination of Silybin and GS-9973 in the treatment of CCl4 induced mice and found that this combination is well tolerated and acts synergistically against HSCs activity, LF and HCC. The combinational use of Silybin and GS-9973 could be a promising therapeutic strategy in patients suffering from LF and even HCC.

Chronic cadmium exposure at environmental-relevant level accelerates the development of hepatotoxicity to hepatocarcinogenesis

Cadmium (Cd) is an environmental heavy metal with long biological half-time and adverse health effects. The long-term toxicity of Cd at low levels remains to be elucidated. Here, we investigated the impact of dietary Cd intake at environmental doses in the full disease cycle from liver injury, fibrosis, inflammation to cancer progression in mouse models and in vitro. We found that chronic low-dose Cd exposure promoted the hepatotoxicity and hepato-pathogenesis in normal and CCl₄ mouse models. Cd enhanced liver injury and accelerated liver fibrosis, a key risk factor for cirrhosis and liver cancer, featured as up-regulation of fibrosis-related markers (TGF-β1, collagen-1, and TIMP1) and activation of hepatic stellate cells. Consistently, Cd increased the inflammation and the infiltration of macrophages and dendritic cells in liver. At late stage, the angiogenetic factors, VEGF and CD34, were elevated, indicating abnormal angiogenesis. At the end of treatment, Cd promoted CCl₄-induced liver cancer formation, including incidence, tumor number and size. These effects were more pronounced in male mice than that in females. The promoting-effects of Cd on fibrosis and angiogenesis were further validated in hepatic stellate cells and liver sinusoidal endothelial cells. PPAR and ERBB signaling pathways were identified as the potential pathways to promote the toxicity of chronic Cd exposure. These findings provide a better understanding about the long-term influence of environmental Cd spanning the entire precancerous lesions-to-cancer formation cycle.

The Endless Sources of Hepatocellular Carcinoma Heterogeneity

Hepatocellular carcinoma (HCC) represents a global health problem. The incidence keeps increasing and current therapeutic options confer limited benefits to the patients. Tumor heterogeneity plays a central role in this context, limiting the availability of predictive biomarkers and complicating the criteria used to choose the most suitable therapeutic option. HCC heterogeneity occurs at different levels: within the population (inter-patient heterogeneity) and within tumors from the same patient (intra-patient and intra-tumor heterogeneity). Experts in the field have made many efforts to classify the patients based on clinicopathological characteristics and molecular signatures; however, there is still much work ahead to be able to integrate the extra-tumor heterogeneity that emerges from the complexity of the tumor microenvironment, which plays a critical role in the pathogenesis of the disease and therapy responses. In this review, we summarize tumor intrinsic and extrinsic sources of heterogeneity of the most common etiologies of HCC and summarize the most recent discoveries regarding the evolutionary trajectory of liver cancer cells and the influence of tumor-extrinsic factors such as the microbiome and the host immune system. We further highlight the potential of novel high-throughput methodologies to contribute to a better understanding of this devastating disease and to the improvement of the clinical management of patients.

Epigenetic Biomarkers for the Diagnosis and Treatment of Liver Disease

Research in the last decades has demonstrated the relevance of epigenetics in controlling gene expression to maintain cell homeostasis, and the important role played by epigenome alterations in disease development. Moreover, the reversibility of epigenetic marks can be harnessed as a therapeutic strategy, and epigenetic marks can be used as diagnosis biomarkers. Epigenetic alterations in DNA methylation, histone post-translational modifications (PTMs), and non-coding RNA (ncRNA) expression have been associated with the process of hepatocarcinogenesis. Here, we summarize epigenetic alterations involved in the pathogenesis of chronic liver disease (CLD), particularly focusing on DNA methylation. We also discuss their utility as epigenetic biomarkers in liquid biopsy for the diagnosis and prognosis of hepatocellular carcinoma (HCC). Finally, we discuss the potential of epigenetic therapeutic strategies for HCC treatment.

The miR-139-5p/peripheral myelin protein 22 axis modulates TGF-β-induced hepatic stellate cell activation and CCl4-induced hepatic fibrosis in mice

Hepatic stellate cells (HSCs) are the major source of extracellular matrix (ECM)-producing myofibroblasts. When activated by multiple injuries, HSCs become proliferative, contractile, inflammatory and chemotactic and are characterized by enhanced ECM production, which plays a central role in hepatic fibrosis initiation and progression. In the present study, through bioinformatics analysis, we identified the abnormal upregulation of Peripheral Myelin Protein 22 (PMP22) in fibrotic murine liver. In CCl₄-induced hepatic fibrosis model in mice and TGF-β-activated hHSCs, PMP22 was observed remarkably upregulated. In TGF-β-stimulated hHSCs, PMP22 silencing hindered, whereas PMP22 overexpression aggravated TGF-β-induced hHSC activation. In CCl₄-induced hepatic fibrosis model in mice, PMP22 silencing improved CCl₄-caused liver damage and fibrotic changes. Through online tools prediction and experimental validation, miR-139-5p was found to bind to the 3'UTR of PMP22 and negatively regulate the expression of PMP22. In contrast to PMP22 silencing, miR-139-5p inhibition enhanced TGF-β-induced hHSC activation; the effects of miR-139-5p inhibition on TGF-β-induced hHSC activation were partially reversed by PMP22 silencing. In conclusion, we identify the abnormal upregulation of PMP22 in TGF-β-activated HSCs and CCl₄-induced hepatic fibrosis model in mice, as well as the pro-fibrotic role of PMP22 through aggravating TGF-β-induced HSCs activation. miR-139-5p targets the 3'UTR of PMP22 and inhibits PMP22 expression; miR-139-5p hinders TGF-β-induced HSCs activation through targeting PMP22.

Blood reelin in the progression of chronic liver disease

PURPOSE

Reelin is an extracellular matrix protein originally found to be associated with neuropsychiatric disorders. Recent findings indicate, that reelin may also play an important role in the process of liver fibrosis as well as in the development of hepatocellular carcinoma (HCC). Against this background, the aim of our study was to explore alterations in blood reelin levels in different stages of chronic liver diseases.

PATIENTS AND METHODS

We analyzed blood samples of patients with chronic liver disease without liver fibrosis (n ​= ​25), with liver fibrosis (n ​= ​36), with liver cirrhosis (n ​= ​74), with HCC (n ​= ​26) as well as of healthy controls (n ​= ​15). Blood reelin concentrations were determined utilizing an enzyme-linked immunosorbent assay.

RESULTS

Blood reelin levels were significantly elevated in patients who had liver fibrosis or cirrhosis compared to patients without liver fibrosis and healthy controls (13.9 (10.2-21.1) ng/ml vs. 11.2 (8.8-16.8) ng/ml, p ​= ​0.032). Importantly, patients with HCC displayed significantly higher reelin concentrations compared to patients with liver cirrhosis alone (27.0 (17.3-35.9) ng/ml vs. 16.6 (11.0-22.7) ng/ml, p ​< ​0.001). Blood reelin was not relevantly linked to liver function, inflammation and etiology of liver disease.

CONCLUSIONS

Our results demonstrate, that blood reelin levels are altered in different stages of chronic liver disease, which makes reelin a potential biomarker in this setting. This may be especially relevant with regard to its use as an additional tumor marker of HCC.

Epigenomic Evaluation of Cholangiocyte Transforming Growth Factor-β Signaling Identifies a Selective Role for Histone 3 Lysine 9 Acetylation in Biliary Fibrosis

BACKGROUND & AIMS

Transforming growth factor β (TGFβ) upregulates cholangiocyte-derived signals that activate myofibroblasts and promote fibrosis. Using epigenomic and transcriptomic approaches, we sought to distinguish the epigenetic activation mechanisms downstream of TGFβ that mediate transcription of fibrogenic signals.

METHODS

Chromatin immunoprecipitation (ChIP)-seq and RNA-seq were performed to assess histone modifications and transcriptional changes following TGFβ stimulation. Histone modifications and acetyltransferase occupancy were confirmed using ChIP assays. Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) was used to investigate changes in chromatin accessibility. Cholangiocyte cell lines and primary cholangiocytes were used for in vitro studies. Mdr2-/- and 3,5-diethoxycarboncyl-1,4-dihydrocollidine (DDC)-fed mice were used as animal models.

RESULTS

TGFβ stimulation caused widespread changes in histone 3 lysine 27 acetylation (H3K27ac), and was associated with global TGFβ-mediated transcription. In contrast, H3K9ac was gained in a smaller group of chromatin sites and was associated with fibrosis pathways. These pathways included overexpression of hepatic stellate cell (HSC) activators such as fibronectin 1 (FN1) and SERPINE1. The promoters of these genes showed H3K9ac enrichment following TGFβ. Of the acetyltransferases responsible for H3K9ac, cholangiocytes predominantly express Lysine Acetyltransferases 2A (KAT2A). Small interfering RNA knockdown of KAT2A or H3K9ac inhibition prevented the TGFβ-mediated increase in FN1 and SERPINE1. SMAD3 ChIP-seq and ATAC-seq suggested that TGFβ-mediated H3K9ac occurs through SMAD signaling, which was confirmed using colocalization and genetic knockdown studies. Pharmacologic inhibition or cholangiocyte-selective deletion of Kat2a was protective in mouse models of biliary fibrosis.

CONCLUSIONS

Cholangiocyte expression of HSC-activating signals occurs through SMAD-dependent, KAT2A-mediated, H3K9ac, and can be targeted to prevent biliary fibrosis.

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.

Paeoniflorin modulates oxidative stress, inflammation and hepatic stellate cells activation to alleviate CCl4-induced hepatic fibrosis by upregulation of heme oxygenase-1 in mice

OBJECTIVES

The role of Paeoniflorin on hepatic fibrosis and the specific mechanisms has not yet been elucidated. Therefore, we explored whether Paeoniflorin exerted protective effects on carbon tetrachloride (CCl4)-induced hepatic fibrosis and the underlying mechanisms.

METHODS

A model of hepatic fibrosis was induced by intraperitoneally injecting with CCl4 (10% 5 μl/g) twice a week for 7 weeks. To explore the effects of Paeoniflorin, mice were treated with Paeoniflorin (100 mg/kg) by gavage once a day at 1 week after modeling until they were sacrificed.

KEY FINDINGS

Paeoniflorin remarkably improved liver function and histopathological changes of hepatic tissues in CCl4-induced liver injury. Besides, the serum MAO enzyme activity and hydroxyproline contents were notably decreased following the intervention of Paeoniflorin. The decreased expression of Vimentin, α-SMA, Col1a and Desmin manifested the inhibition of the hepatic stellate cells (HSCs) activation. Interestingly, Paeoniflorin intervention significantly upregulated the expression of heme oxygenase-1, and attenuated the inflammatory cytokines production as well as the CCl4-induced oxidative stress imbalance.

CONCLUSIONS

Paeoniflorin could effectively alleviate CCl4-induced hepatic fibrosis by upregulation of heme oxygenase-1, and it might be a new effective option for the comprehensive treatment of hepatic fibrosis.

Dual Pharmacological Targeting of HDACs and PDE5 Inhibits Liver Disease Progression in a Mouse Model of Biliary Inflammation and Fibrosis

Simple Summary

Chronic liver injury and inflammation leads to excessive deposition of extracellular matrix, known as liver fibrosis, and the distortion of the hepatic parenchyma. Liver fibrosis may progress to cirrhosis, a condition in which hepatic function is impaired and most cases of liver tumors occur. Currently, there are no effective therapies to inhibit and reverse the progression of liver fibrosis, and therefore, chronic liver disease remains a global health problem. In this study we have tested the efficacy of a new class of molecules that simultaneously target two molecular pathways known to be involved in the pathogenesis of hepatic fibrosis. In a clinically relevant mouse model of liver injury and inflammation we show that the combined inhibition of histones deacetylases and the cyclic guanosine monophosphate (cGMP) phosphodiesterase phosphodiesterase 5 (PDE5) results in potent anti-inflammatory and anti-fibrotic effects. Our findings open new avenues for the treatment of liver fibrosis and therefore, the prevention of hepatic carcinogenesis.

Abstract

Liver fibrosis, a common hallmark of chronic liver disease (CLD), is characterized by the accumulation of extracellular matrix secreted by activated hepatic fibroblasts and stellate cells (HSC). Fibrogenesis involves multiple cellular and molecular processes and is intimately linked to chronic hepatic inflammation. Importantly, it has been shown to promote the loss of liver function and liver carcinogenesis. No effective therapies for liver fibrosis are currently available. We examined the anti-fibrogenic potential of a new drug (CM414) that simultaneously inhibits histone deacetylases (HDACs), more precisely HDAC1, 2, and 3 (Class I) and HDAC6 (Class II) and stimulates the cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) pathway activity through phosphodiesterase 5 (PDE5) inhibition, two mechanisms independently involved in liver fibrosis. To this end, we treated Mdr2-KO mice, a clinically relevant model of liver inflammation and fibrosis, with our dual HDAC/PDE5 inhibitor CM414. We observed a decrease in the expression of fibrogenic markers and collagen deposition, together with a marked reduction in inflammation. No signs of hepatic or systemic toxicity were recorded. Mechanistic studies in cultured human HSC and cholangiocytes (LX2 and H69 cell lines, respectively) demonstrated that CM414 inhibited pro-fibrogenic and inflammatory responses, including those triggered by transforming growth factor β (TGFβ). Our study supports the notion that simultaneous targeting of pro-inflammatory and fibrogenic mechanisms controlled by HDACs and PDE5 with a single molecule, such as CM414, can be a new disease-modifying strategy.

Epigenetics in hepatocellular carcinoma development and therapy: The tip of the iceberg

Hepatocellular carcinoma (HCC) is a deadly tumour whose causative agents are generally well known, but whose pathogenesis remains poorly understood. Nevertheless, key genetic alterations are emerging from a heterogeneous molecular landscape, providing information on the tumorigenic process from initiation to progression. Among these molecular alterations, those that affect epigenetic processes are increasingly recognised as contributing to carcinogenesis from preneoplastic stages. The epigenetic machinery regulates gene expression through intertwined and partially characterised circuits involving chromatin remodelers, covalent DNA and histone modifications, and dedicated proteins reading these modifications. In this review, we summarise recent findings on HCC epigenetics, focusing mainly on changes in DNA and histone modifications and their carcinogenic implications. We also discuss the potential drugs that target epigenetic mechanisms for HCC treatment, either alone or in combination with current therapies, including immunotherapies.

Capsaicin attenuates liver fibrosis by targeting Notch signaling to inhibit TNF-α secretion from M1 macrophages

BACKGROUND

Capsaicin is a chili pepper extract with multiple therapeutic properties including anti-liver fibrosis. However, the paucity of its underlying mechanisms limited its widely clinical application.

METHODS

In the present study, carbon tetrachloride (CCl₄) was used to induce liver fibrosis in mice, and transforming growth factorβ1 (TGFβ1) was used to mimic liver fibrosis in vitro. Flow cytometry was conducted to determine the expression of CD80. The inflammatory factors level was examined by ELISA, and gene expression was detected by real-time PCR and western blot.

RESULTS

Here, we show that capsaicin attenuates liver fibrosis progression by mediating macrophage inflammatory response. Capsaicin inhibited M1 polarization of macrophage by regulating Notch signaling leading to the reduced secretion of inflammatory cytokine TNF-α that correspondingly attenuates myofibroblasts regeneration and fibrosis formation of hepatocyte stellate cells (HSCs).

CONCLUSION

Taken together, capsaicin alleviates liver fibrosis by inactivation of Notch signaling and further inhibiting TNF-α secretion from M1 macrophage. Targeting TNF-α or Notch signaling in macrophage represents a promising strategy to combat liver fibrosis.

Epigenetics in Liver Fibrosis: Could HDACs be a Therapeutic Target?

Chronic liver diseases (CLD) represent a worldwide health problem. While CLDs may have diverse etiologies, a common pathogenic denominator is the presence of liver fibrosis. Cirrhosis, the end-stage of CLD, is characterized by extensive fibrosis and is markedly associated with the development of hepatocellular carcinoma. The most important event in hepatic fibrogenesis is the activation of hepatic stellate cells (HSC) following liver injury. Activated HSCs acquire a myofibroblast-like phenotype becoming proliferative, fibrogenic, and contractile cells. While transient activation of HSCs is part of the physiological mechanisms of tissue repair, protracted activation of a wound healing reaction leads to organ fibrosis. The phenotypic changes of activated HSCs involve epigenetic mechanisms mediated by non-coding RNAs (ncRNA) as well as by changes in DNA methylation and histone modifications. During CLD these epigenetic mechanisms become deregulated, with alterations in the expression and activity of epigenetic modulators. Here we provide an overview of the epigenetic alterations involved in fibrogenic HSCs transdifferentiation with particular focus on histones acetylation changes. We also discuss recent studies supporting the promising therapeutic potential of histone deacetylase inhibitors in liver fibrosis.

Understanding Dietary Intervention-Mediated Epigenetic Modifications in Metabolic Diseases

The global prevalence of metabolic disorders, such as obesity, diabetes and fatty liver disease, is dramatically increasing. Both genetic and environmental factors are well-known contributors to the development of these diseases and therefore, the study of epigenetics can provide additional mechanistic insight. Dietary interventions, including caloric restriction, intermittent fasting or time-restricted feeding, have shown promising improvements in patients' overall metabolic profiles (i.e., reduced body weight, improved glucose homeostasis), and an increasing number of studies have associated these beneficial effects with epigenetic alterations. In this article, we review epigenetic changes involved in both metabolic diseases and dietary interventions in primary metabolic tissues (i.e., adipose, liver, and pancreas) in hopes of elucidating potential biomarkers and therapeutic targets for disease prevention and treatment.

Antifibrotic Effects of a Barbituric Acid Derivative on Liver Fibrosis by Blocking the NF-κB Signaling Pathway in Hepatic Stellate Cells

Hepatic stellate cells (HSCs) are the major profibrogenic cells that promote the pathogenesis of liver fibrosis. The crosstalk between transforming growth factor-β1 (TGF-β1) signaling and lipopolysaccharide (LPS)-induced NF-κB signaling plays a critical role in accelerating liver fibrogenesis. Until now, there have been no FDA-approved drug treatments for liver fibrosis. Barbituric acid derivatives have been used as antiasthmatic drugs in the clinic; however, the effect of barbituric acid derivatives in treating liver fibrosis remains unknown. In this study, we synthesized a series of six barbituric acid (BA) derivatives, and one of the compounds, BA-5, exhibited the best ability to ameliorate TGF-β1-induced HSC activation without overt cytotoxic effects. Then, we treated HSCs and RAW264.7 macrophages with BA-5 to analyze the cross-talk of anti-fibrotic and anti-inflammatory effects. Carbon tetrachloride (CCl₄)-induced liver fibrosis mouse model was used to evaluate the therapeutic effects of BA-5. Treatment with BA-5 inhibited TGF-β1-induced α-SMA, collagen1a2, and phosphorylated smad2/3 expression in HSCs. Furthermore, BA-5 treatment reversed the LPS-induced reduction in BAMBI protein and decreased IκBα and NF-κB phosphorylation in HSCs. NF-κB nuclear translocation, MCP-1 secretion, and ICAM-1 expression were also inhibited in BA-5-treated HSCs. Conditioned medium collected from BA-5-treated HSCs showed a reduced ability to activate RAW264.7 macrophages by inhibiting the MAPK pathway. In the mouse model, BA-5 administration reduced CCl₄-induced liver damage, liver fibrosis, and F4/80 expression without any adverse effects. In conclusion, our study showed that the barbituric acid derivative BA-5 inhibits HSCs activation and liver fibrosis by blocking both the TGF-β1 and LPS-induced NF-κB signaling pathways and further inhibits macrophages recruitment and activation.

β-Sitosterol attenuates carbon tetrachloride-induced oxidative stress and chronic liver injury in rats

Chronic liver diseases are clinically silent and responsible for significant morbidity and mortality worldwide. β-Sitosterol (BSS), major phytosterol in plants, has a wide spectrum of protective effect against various chronic ailments. We investigated the hepatoprotective effect of BSS against carbon tetrachloride (CCl₄)-induced chronic liver injury in rats. Thirty rats were divided into five groups, with six animals in each group. Group I rats served as control while groups II, III, IV, and V rats were injected intraperitoneally with CCl₄ (0.2 mL/100 g b.w. in olive oil (1:1)) for 7 consecutive weeks. After 7 weeks, group II rats were left without any treatments and served as CCl₄ alone group, while groups III, IV, and V rats were treated with BSS 25 and 50 mg/kg b.w. and silymarin 100 mg/kg b.w. as oral post-treatments respectively, for the next 4 weeks. At the end of the experiment, hepatotoxicity marker enzymes in serum, oxidative stress, and fibrosis marker were analyzed. CCl₄ administration caused significant elevation of marker enzymes of hepatotoxicity in serum and increased lipid peroxidation and fibrosis markers such as hydroxyproline, collagen, α-smooth muscle actin, vimentin, desmin, and matrix metalloproteinases 9 in liver tissue of rats. This treatment also caused a significant diminution of intracellular enyzmic antioxidants such as SOD and CAT in the liver tissue of rats. All the above adversities were significantly mitigated by the BSS post-treatments. The results suggest that BSS could have a hepatoprotective effect against oxidative stress-mediated CLD induced by CCl₄.

Links between Fibrogenesis and Cancer: Mechanistic and Therapeutic Challenges

Fibrosis is the end-stage of chronic inflammatory diseases and tissue damage resulting from a dysregulated wound-healing response [...].