Fusion protein of retinol-binding protein and albumin domain III reduces liver fibrosis

Optimizing the Amino Acid Sequence Enhances the Productivity and Bioefficacy of the RBP-Albumin Fusion Protein

The significant growth of the global protein drug market, including fusion proteins, emphasizes the crucial role of optimizing amino acid sequences to enhance the productivity and bioefficacy. Among these fusion proteins, RBP-IIIA-IB, comprising retinol-binding protein in conjunction with the albumin domains, IIIA and IB, has displayed efficacy in alleviating liver fibrosis by inhibiting the activation of hepatic stellate cells (HSCs). This study aimed to address the issue of the low productivity in RBP-IIIA-IB. To induce structural changes, the linking sequence, EVDD, between domain IIIA and IB in RBP-IIIA-IB was modified to DGPG, AAAA, and GGPA. Among these, RBP-IIIA-AAAA-IB demonstrated an increase in yield (>4-fold) and a heightened inhibition of HSC activation. Furthermore, we identified amino acid residues that could form disulfide bonds when substituted with cysteine. Through the mutation of N453S-V480S in RBP-IIIA-AAAA-IB, the productivity further increased by over 9-fold, accompanied by an increase in anti-fibrotic activity. Overall, there was a more than 30-fold increase in the fusion protein's yield. These findings demonstrate the effectiveness of modifying linker sequences and introducing extra disulfide bonds to improve both the production yield and biological efficacy of fusion proteins.

Fusion Protein of RBP and Albumin Domain III Reduces Lung Fibrosis by Inactivating Lung Stellate Cells

Activated stellate cells play a role in fibrosis development in the liver, pancreas, and kidneys. The fusion protein R-III, which consists of retinol-binding protein and albumin domain III, has been demonstrated to attenuate liver and renal fibrosis by suppressing stellate cell activation. In this study, we investigated the efficacy of R-III against bleomycin-induced lung fibrosis in mice. R-III reduced lung fibrosis and primarily localized in autofluorescent cells in the lung tissue. Furthermore, we isolated lung stellate cells (LSCs) from rat lungs using the isolation protocol employed for hepatic stellate cells (HSCs). LSCs shared many characteristics with HSCs, including the presence of vitamin A-containing lipid droplets and the expression of alpha-smooth muscle actin and collagen type I, markers for activated HSCs/myofibroblasts. LSCs spontaneously transdifferentiated into myofibroblasts in in vitro culture, which was inhibited by R-III. These findings suggest that R-III may reduce lung fibrosis by inactivating LSCs and could be a promising treatment for extrahepatic fibrosis.

Insights on drug and gene delivery systems in liver fibrosis

Complications of the liver are amongst the world's worst diseases. Liver fibrosis is the first stage of liver problems, while cirrhosis is the last stage, which can lead to death. The creation of effective anti-fibrotic drug delivery methods appears critical due to the liver's metabolic capacity for drugs and the presence of insurmountable physiological impediments in the way of targeting. Recent breakthroughs in anti-fibrotic agents have substantially assisted in fibrosis; nevertheless, the working mechanism of anti-fibrotic medications is not fully understood, and there is a need to design delivery systems that are well-understood and can aid in cirrhosis. Nanotechnology-based delivery systems are regarded to be effective but they have not been adequately researched for liver delivery. As a result, the capability of nanoparticles in hepatic delivery was explored. Another approach is targeted drug delivery, which can considerably improve efficacy if delivery systems are designed to target hepatic stellate cells (HSCs). We have addressed numerous delivery strategies that target HSCs, which can eventually aid in fibrosis. Recently genetics have proved to be useful, and methods for delivering genetic material to the target place have also been investigated where different techniques are depicted. To summarize, this review paper sheds light on the most recent breakthroughs in drug and gene-based nano and targeted delivery systems that have lately shown useful for the treatment of liver fibrosis and cirrhosis.

Activin B promotes the initiation and progression of liver fibrosis

The role of activin B, a transforming growth factor β (TGFβ) superfamily cytokine, in liver health and disease is largely unknown. We aimed to investigate whether activin B modulates liver fibrogenesis. Liver and serum activin B, along with its analog activin A, were analyzed in patients with liver fibrosis from different etiologies and in mouse acute and chronic liver injury models. Activin B, activin A, or both was immunologically neutralized in mice with progressive or established carbon tetrachloride (CCl₄ )-induced liver fibrosis. Hepatic and circulating activin B was increased in human patients with liver fibrosis caused by several liver diseases. In mice, hepatic and circulating activin B exhibited persistent elevation following the onset of several types of liver injury, whereas activin A displayed transient increases. The results revealed a close correlation of activin B with liver injury regardless of etiology and species. Injured hepatocytes produced excessive activin B. Neutralizing activin B largely prevented, as well as improved, CCl₄ -induced liver fibrosis, which was augmented by co-neutralizing activin A. Mechanistically, activin B mediated the activation of c-Jun-N-terminal kinase (JNK), the induction of inducible nitric oxide synthase (iNOS) expression, and the maintenance of poly (ADP-ribose) polymerase 1 (PARP1) expression in injured livers. Moreover, activin B directly induced a profibrotic expression profile in hepatic stellate cells (HSCs) and stimulated these cells to form a septa structure. Conclusions: We demonstrate that activin B, cooperating with activin A, mediates the activation or expression of JNK, iNOS, and PARP1 and the activation of HSCs, driving the initiation and progression of liver fibrosis.

Fibrogenic Pathways in Metabolic Dysfunction Associated Fatty Liver Disease (MAFLD)

The prevalence of nonalcoholic fatty liver disease (NAFLD), recently also re-defined as metabolic dysfunction associated fatty liver disease (MAFLD), is rapidly increasing, affecting ~25% of the world population. MALFD/NAFLD represents a spectrum of liver pathologies including the more benign hepatic steatosis and the more advanced non-alcoholic steatohepatitis (NASH). NASH is associated with enhanced risk for liver fibrosis and progression to cirrhosis and hepatocellular carcinoma. Hepatic stellate cells (HSC) activation underlies NASH-related fibrosis. Here, we discuss the profibrogenic pathways, which lead to HSC activation and fibrogenesis, with a particular focus on the intercellular hepatocyte–HSC and macrophage–HSC crosstalk.

Combination therapy based on targeted nano drug co-delivery systems for liver fibrosis treatment: A review

Liver fibrosis is the hallmark of liver disease and occurs prior to the stages of cirrhosis and hepatocellular carcinoma. Any type of liver damage or inflammation can result in fibrosis. Fibrosis does not develop overnight, but rather as a result of the long-term action of injury factors. At present, however, there are no good treatment methods or specific drugs other than removing the pathogenic factors. Drug application is still limited, which means that drugs with good performance in vitro cannot achieve good therapeutic effects in vivo, owing to various factors such as poor drug targeting, large side effects, and strong hydrophobicity. Hepatic stellate cells (HSC) are the primary effector cells in liver fibrosis. The nano-drug delivery system is a new and safe drug delivery system that has many advantages which are widely used in the field of liver fibrosis. Drug resistance and side effects can be reduced when two or more drugs are used in combination drug delivery. Combination therapy of drugs with different targets has emerged as a novel approach to treating liver fibrosis, and the nano co-delivery system enhances the benefits of combination therapy. While nano co-delivery systems can maximize benefits while avoiding drug side effects, this is precisely the advantage of the nano co-delivery system. This review briefly described the pathogenesis and current treatment strategies, the different co-delivery systems of combination drugs in the nano delivery system, and targeting strategies for nano delivery systems on liver fibrosis therapy. Because of their superior performance, nano delivery systems and targeting drug delivery systems have received a lot of attention in the new drug delivery system. The new delivery systems offer a new pathway in the treatment of liver fibrosis, and it is believed that it can be a new treatment for fibrosis in the future. Nano co-delivery system of combination drugs and targeting strategies has proven the effectiveness of anti-fibrosis at the experimental level.

Inhibition of Hepatic Stellate Cell Activation Suppresses Tumorigenicity of Hepatocellular Carcinoma in Mice

Transdifferentiation (or activation) of hepatic stellate cells (HSCs) to myofibroblasts is a key event in liver fibrosis. Activated HSCs in the tumor microenvironment reportedly promote tumor progression. This study analyzed the effect of an inhibitor of HSC activation, retinol-binding protein–albumin domain III fusion protein (R-III), on protumorigenic functions of HSCs. Although conditioned medium collected from activated HSCs enhanced the migration, invasion, and proliferation of the hepatocellular carcinoma cell line Hepa-1c1c7, this effect was not observed in Hepa-1c1c7 cells treated with conditioned medium from R-III–exposed HSCs. In a subcutaneous tumor model, larger tumors with increased vascular density were formed in mice transplanted with Hepa-1c1c7+HSC than in mice transplanted with Hepa-1c1c7 cells alone. Intriguingly, when Hepa-1c1c7+HSC–transplanted mice were injected intravenously with R-III, a reduction in vascular density and extended tumor necrosis were observed. In an orthotopic tumor model, co-transplantation of HSCs enhanced tumor growth, angiogenesis, and regional metastasis accompanied by increased peritumoral lymphatic vessel density, which was abolished by R-III. In vitro study showed that R-III treatment affected the synthesis of pro-angiogenic and anti-angiogenic factors in activated HSCs, which might be the potential mechanism underlying the R-III effect. These findings suggest that the inhibition of HSC activation abrogates HSC-induced tumor angiogenesis and growth, which represents an attractive therapeutic strategy.

Vitamin A-coupled stem cell-derived extracellular vesicles regulate the fibrotic cascade by targeting activated hepatic stellate cells in vivo

Allogeneic transplantation of mesenchymal stem cell-derived extracellular vesicles (EVs) offers great potential for treating liver fibrosis. However, owing to their intrinsic surface characteristics, bare EVs are non-specifically distributed in the liver tissue after systemic administration, leading to limited therapeutic efficacy. To target activated hepatic stellate cells (HSCs), which are responsible for hepatic fibrogenesis, vitamin A-coupled small EVs (V-EVs) were prepared by incorporating vitamin A derivative into the membrane of bare EVs. No significant differences were found in the particle size and morphology between bare and V-EVs. In addition, surface engineering of EVs did not affect the expression of surface marker proteins (e.g., CD63 and CD9), as demonstrated by flow cytometry. Owing to the surface incorporation of vitamin A, V-EVs were selectively taken up by activated HSCs via receptor-mediated endocytosis. When systemically administered to mice with liver fibrosis, V-EVs effectively targeted activated HSCs in the liver tissue, resulting in reversal of the fibrotic cascade. Consequently, even at a 10-fold lower dose, V-EVs exhibited comparable anti-fibrotic effects to those of bare EVs, substantiating their therapeutic potential for liver fibrosis.

Albumin inhibits the nuclear translocation of Smad3 via interleukin-1beta signaling in hepatic stellate cells

Activation of quiescent hepatic stellate cells (HSCs) to myofibroblasts plays a key role in liver fibrosis. We had previously shown that albumin and its derivative, R-III (a retinol-binding protein—albumin domain III fusion protein), inhibited HSC activation by sequestering retinoic acid (RA) and that R-III administration reduced carbon tetrachloride (CCl₄)-induced liver fibrosis. In this study, we aimed to elucidate the mechanism of action of albumin downstream of RA sequestration. Nuclear factor-κB p65 was evenly distributed in the cytoplasm in activated mouse HSCs, whereas albumin expression or R-III treatment (albumin/R-III) caused the nuclear translocation of p65, probably via RA sequestration, resulting in a dramatic increase in interleukin-1beta (IL-1β) expression. Albumin/R-III in turn induced the phosphorylation of Smad3 at the linker region, inhibiting its nuclear import in an IL-1β-dependent manner. Consistent with the in vitro results, the level of IL-1β mRNA expression was higher in CCl₄/R-III-treated livers than in CCl₄-treated livers. These findings reveal that albumin/R-III inhibits the transforming growth factor-β-Smad3 signaling as well as the retinoic acid receptor-mediated pathway, which probably contributes to the inhibition of HSC activation, and suggest that R-III may be an anti-fibrotic drug candidate.

Inhibition of Renal Stellate Cell Activation Reduces Renal Fibrosis

Interstitial fibrosis is a common feature of chronic kidney disease, and platelet-derived growth factor receptor-β (PDGFR-β)-positive mesenchymal cells are reportedly the major source of scar-producing myofibroblasts. We had previously demonstrated that albumin and its derivative R-III (a retinol-binding protein-albumin domain III fusion protein) inhibited the transdifferentiation/activation of hepatic stellate cells (HSCs) to myofibroblasts and that R-III administration reduced liver fibrosis. In this study, we isolated cells (referred to as renal stellate cells, RSCs) from rat kidney tissues using the HSC isolation protocol and compared their morphological and biochemical characteristics with those of HSCs. RSCs shared many characteristics with HSCs, such as storage of vitamin A-containing lipid droplets and expression of HSC markers as well as pericyte markers. RSCs underwent spontaneous transdifferentiation into myofibroblasts in in vitro culture, which was inhibited by albumin expression or R-III treatment. We also evaluated the therapeutic effects of R-III in unilateral ureteral obstruction (UUO)-induced renal fibrosis in mice. Injected R-III localized predominantly in cytoglobin/stellate cell activation-associated protein (Cygb/STAP)-positive cells in the kidney and reduced renal fibrosis. These findings suggest that RSCs can be recognized as the renal counterparts of HSCs and that RSCs represent an attractive therapeutic target for anti-fibrotic therapy.

A pocket-escaping design to prevent the common interference with near-infrared fluorescent probes in vivo

Near-infrared (NIR) fluorescent probes are among the most attractive chemical tools for biomedical imaging. However, their in vivo applications are hindered by albumin binding, generating unspecific fluorescence that masks the specific signal from the analyte. Here, combining experimental and docking methods, we elucidate that the reason for this problem is an acceptor (A) group-mediated capture of the dyes into hydrophobic pockets of albumin. This pocket-capturing phenomenon commonly applies to dyes designed under the twisted intramolecular charge-transfer (TICT) principle and, therefore, represents a generic but previously unidentified backdoor problem. Accordingly, we create a new A group that avoids being trapped into the albumin pockets (pocket-escaping) and thereby construct a NIR probe, BNLBN, which effectively prevents this backdoor problem with increased imaging accuracy for liver fibrosis in vivo. Overall, our study explains and overcomes a fundamental problem for the in vivo application of a broad class of bioimaging tools.

Mining TCGA Database for Tumor Microenvironment-Related Genes of Prognostic Value in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common and lethal malignancies. Recent studies reveal that tumor microenvironment (TME) components significantly affect HCC growth and progression, particularly the infiltrating stromal and immune cells. Thus, mining of TME-related biomarkers is crucial to improve the survival of patients with HCC. Public access of The Cancer Genome Atlas (TCGA) database allows convenient performance of gene expression-based analysis of big data, which contributes to the exploration of potential association between genes and prognosis of a variety of malignancies, including HCC. The "Estimation of STromal and Immune cells in MAlignant Tumors using Expression data" algorithm renders the quantification of the stromal and immune components in TME possible by calculating the stromal and immune scores. Differentially expressed genes (DEGs) were screened by dividing the HCC cohort of TCGA database into high- and low-score groups according to stromal and immune scores. Further analyses of functional enrichment and protein-protein interaction networks show that the DEGs are mainly involved in immune response, cell adhesion, and extracellular matrix. Finally, seven DEGs have significant association with HCC poor outcomes. These genes contain FABP3, GALNT5, GPR84, ITGB6, MYEOV, PLEKHS1, and STRA6 and may be candidate biomarkers for HCC prognosis.

Targeted Delivery of an siRNA/PNA Hybrid Nanocomplex Reverses Carbon Tetrachloride-Induced Liver Fibrosis

Liver fibrosis is a wound healing process with excessive accumulation of extracellular matrix in the liver. We recently discovered a PCBP2 siRNA that reverses fibrogenesis in activated hepatic stellate cells (HSCs), which are the key players in liver fibrogenesis. However, targeted delivery of siRNAs to HSCs still remains a challenge. Herein, we developed a new strategy to fabricate a multicomponent nanocomplex using siRNA/PNA hybrid instead of chemically conjugated siRNA, thus increasing the scalability and feasibility of the siRNA nanocomplex for animal studies. We modified the nanocomplex with an insulin growth factor 2 receptor (IGF2R)-specific peptide, which specifically binds to activated HSCs. The siRNA nanocomplex shows a controllable size and high serum stability. The nanocomplex also demonstrates high cellular uptake in activated HSCs in vitro and in vivo. Anti-fibrotic activity of the siRNA nanocomplex was evaluated in rats with carbon tetrachloride-induced liver fibrosis. Treatment with the PCBP2 siRNA nanocomplex significantly inhibits the mRNA expressions of PCBP2 and type I collagen in fibrotic liver. Histology study revealed that the siRNA nanocomplex efficiently reduces the protein level of type I collagen and reverses liver fibrosis. Our data suggest that the nanocomplex efficiently delivers the siRNA to fibrotic liver and produces a potent anti-fibrotic effect.

Targeted Drug Delivery to Hepatic Stellate Cells for the Treatment of Liver Fibrosis

Liver fibrosis is caused by excessive accumulation of extracellular matrix during chronic liver injuries. Although clinical evidence suggests that liver fibrosis can be reversed, there is no standard therapy for liver fibrosis. Moreover, there is a lack of diagnostic tools to detect early-stage liver fibrosis. Activation of hepatic stellate cells (HSCs) is the key step during liver fibrogenesis, and its mechanism has been extensively studied by various cell culture and animal models. Targeted delivery of therapeutic agents to activated HSCs is therefore critical for the successful treatment of liver fibrosis. A number of protein markers have been found to be overexpressed in activated HSCs, and their ligands have been used to specifically deliver various antifibrotic agents. In this review, we summarize these HSC-specific protein markers and their ligands for targeted delivery of antifibrotic agents.

Galectin-1 gene silencing inhibits the activation and proliferation but induces the apoptosis of hepatic stellate cells from mice with liver fibrosis

Liver fibrosis is a serious threat to human health, and there is currently no effective clinical drug for treatment of the disease. Although Galectin-1 is effective, its role in liver function, inflammation, matrix metalloproteinases and the activation of hepatic stellate cells (HSCs) remains to be elucidated. The aim of the present study was to elucidate the effect of Galectin-1 on the activation, proliferation and apoptosis of HSCs in a mouse model of liver fibrosis. Following successful model establishment and tissue collection, mouse HSCs (mHSCs) were identified and an mHSC line was constructed. Subsequently, to determine the role of Galectin-1 in liver fibrosis, the expression levels of transforming growth factor (TGF)-β1, connective tissue growth factor (CTGF) and α-smooth muscle actin (α-SMA) pre- and post-transfection were evaluated by reverse transcription-quantitative polymerase chain reaction and western blot analyses. In addition, the effects of Galectin-1 on the biological behavior and mitochondrial function of mHSCs were determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry and a scratch test. It was first observed that the expression levels of Galectin-1, TGF-β1, CTGF and α-SMA were downregulated by silencing the gene expression of Galectin-1. Additionally, silencing the gene expression of Galectin-1 inhibited cell cycle progression, proliferation and migration but induced the apoptosis of mHSCs from mice with liver fibrosis. Furthermore, the in vivo experimental results suggested that silencing the gene expression of Galectin-1 improved liver fibrosis. Collectively, it was concluded that silencing the gene expression of Galectin-1 ameliorates liver fibrosis and that functionally suppressing Galectin-1 may be a future therapeutic strategy for liver fibrosis.

A Macropinocytosis-Intensifying Albumin Domain-Based scFv Antibody and Its Conjugate Directed against K-Ras Mutant Pancreatic Cancer

Enhanced macropinocytosis has been found in K-Ras mutant pancreatic cancer cells, through which albumin can massively enter into the K-Ras-driven cancer cells, suggesting its role in serving as a macropinocytosis-intensifying drug delivery carrier. In the present study, a novel recombinant protein Fv-LDP-D3 and its reconstituted analogue Fv-LDP-D3-AE were designed and prepared. Fv is the fragment of an anti-EGFR antibody, D3 is the domain III of human serum albumin (HSA), LDP is the apoprotein of the antitumor antibiotic lidamycin (LDM), and AE is an extremely cytotoxic enediyne chromophore derived from LDM. As shown, the recombinant protein Fv-LDP-D3 presented intensive and selective binding capacity to pancreatic cancer cells and inhibited cell proliferation by blocking EGFR signaling. Moreover, Fv-LDP-D3 showed prominent tumor imaging in pancreatic carcinoma xenograft. The reconstituted, enediyne-integrated analogue Fv-LDP-D3-AE displayed highly potent cytotoxicity to pancreatic cancer cells through apoptosis induction and G2/M arrest. Fv-LDP-D3 and Fv-LDP-D3-AE markedly inhibited the tumor growth of the pancreatic carcinoma AsPC-1 xenograft. Study results indicated that the novel recombinant protein displays both EGFR-targeting and macropinocytosis-intensifying attributes, presenting a new format of scFv antibody that integrates with albumin domain III. It might be a feasible strategy to develop targeted drugs for K-Ras mutant pancreatic cancer.

Protective effects of selenium-glutathione-enriched probiotics on CCl4-induced liver fibrosis

Hepatic fibrosis is a common pathological basis of liver cirrhosis and hepatocellular carcinomas. So, prevention and treatment of liver fibrosis is one of the crucial therapeutic goals in hepatology. Organic selenium, glutathione or probiotics supplementation could ameliorate hepatic fibrosis, respectively. The purpose of this study is to develop a novel selenium-glutathione-enriched probiotics (SGP) and to investigate its protective effect on CCl₄-induced liver fibrosis in rats. Yeast strains with the high-yield glutathione were isolated and identified by analysis of 26S ribosomal DNA sequences. The fermentation parameters of SGP were optimized through single-factor, Plackett-Burman (PB) design and response surface methodology (RSM). The final SGP contained 38.4 μg/g of organic selenium, 34.1 mg/g of intracellular glutathione, approximately 1×10¹⁰ CFU/g live Saccharomyces cerevisiae and 1×10¹² CFU/g live Lactobacillus acidophilus. SGP had better protective effects on liver fibrosis than selenium, glutathione or probiotics, respectively. The hepatic silent information regulator 1 (SIRT1) level was down-regulated and oxidative stress, endoplasmic reticulum (ER) stress, inflammation and phosphorylated MAPK was increased in CCl₄-treated rats. However, SGP can significantly reverse these changes caused by CCl₄. Our findings suggest that SGP was effective in attenuating liver fibrosis by the activation of SIRT1 signaling and attenuating hepatic oxidative stress, ER stress, inflammation and MAPK signaling.

Mechanisms of CCl4-induced liver fibrosis with combined transcriptomic and proteomic analysis

The classic toxicity of carbon tetrachloride (CCl4) is to induce liver lesion and liver fibrosis. Liver fibrosis is a consequence of chronic liver lesion, which can progress into liver cirrhosis even hepatocarcinoma. However, the toxicological mechanisms of CCl4-induced liver fibrosis remain not fully understood. We combined transcriptomic and proteomic analysis and biological network technology, predicted toxicological targets and regulatory networks of CCl4 in liver fibrosis. Wistar rats were treated with CCl4 for 9 weeks. Histopathological changes, hydroxyproline (Hyp) contents, serum ALT and AST in the CCl4-treated group were significantly higher than that of CCl4-untreated group. CCl4-treated and -untreated liver tissues were examined by microarray and iTRAQ. The results showed that 3535 genes (fold change ≥ 1.5, P < 0.05) and 1412 proteins (fold change ≥ 1.2, P < 0.05) were differentially expressed. Moreover, the integrative analysis of transcriptomics and proteomics data showed 523 overlapped proteins, enriched in 182 GO terms including oxidation reduction, response to oxidative stress, inflammatory response, extracellular matrix organization, etc. Furthermore, KEGG pathway analysis showed that 36 pathways including retinol metabolism, PPAR signaling pathway, glycolysis/gluconeogenesis, arachidonic acid metabolism, metabolism of xenobiotics by cytochrome P450 and drug metabolism. Network of protein-protein interaction (PPI) and key function with their related targets were performed and the degree of network was calculated with Cytoscape. The expression of key targets such as CYP4A3, ALDH2 and ALDH7A1 decreased after CCl4 treatment. Therefore, the toxicological mechanisms of CCl4-induced liver fibrosis may be related with multi biological process, pathway and targets which may provide potential protection reaction mechanism for CCl4 detoxication in the liver.

Therapeutic value of melatonin post-treatment on CCl4-induced fibrotic rat liver

Melatonin is known for being beneficial in targeting liver diseases. This study aimed to investigate whether melatonin post-treatment is capable of rat carbon tetrachloride (CCl4)-induced liver fibrosis reduction. Thirty-two male Sprague-Dawley rats were divided into 4 groups: normal; fibrosis with CCl4 injection (1 mL/kg) twice weekly for 8 weeks; phosphate-buffered saline (PBS); and melatonin (20 mg/kg) for a further 4 weeks on cessation of CCl4. At the beginning of week 13, liver tissue samples were used for hematoxylin-eosin (H&E), periodic acid-Schiff (PAS), Masson’s trichrome (MT), and Oil Red O staining, quantitative real-time PCR (qRT-PCR) analysis of the matrix metalloproteinase-9 (MMP-9), MMP-13, transforming growth factor-β1 (TGF-β1), Bcl-2, and Bax genes as well as immunofluorescence (IF) of the first 3, and sera for measurement of aspartate aminotransferase (AST), alanine aminotransferase (ALT), albumin, and hydroxyproline. Chronic administration of CCl4 followed by considerable increase in tissue disruption, macro- and micro-vesicles, collagen, lipid droplets (LDs), AST, ALT, hydroxyproline, TGF-β1, and Bax, and decrease in glycogen depository, albumin, Bcl-2, MMP-9, and MMP-13; however, the pattern was reverse when it comes to melatonin treatment (for all p < 0.05). Our results reveal the beneficial aspects of melatonin in treatment of liver fibrosis probably via inhibition of TGF-β1expression.

Non-coding RNA-mediated epigenetic regulation of liver fibrosis

Hepatic stellate cells (HSC) activation plays a key role in liver fibrosis. Numerous studies have indicated that non-coding RNAs (ncRNAs) control liver fibrosis and fibroblasts proliferation. Greater knowledge of the role of the ncRNAs-mediated epigenetic mechanism in liver fibrosis could improve understanding of the liver fibrosis pathogenesis. The aim of this review is to describe the present knowledge about the ncRNAs significantly participating in liver fibrosis and HSC activation, and look ahead on new perspectives of ncRNAs-mediated epigenetic mechanism research. Moreover, we will discuss examples of non-coding RNAs that interact with histone modification or DNA methylation to regulate gene expression in liver fibrosis. Diverse classes of ncRNAs, ranging from microRNAs (miRs) to long non-coding RNAs (LncRNAs), have emerged as key regulators of several important aspects of function, including cell proliferation, activation, etc. In addition, recent advances suggest the important role of ncRNAs transcripts in epigenetic gene regulation. Targeting the miRs and LncRNAs can be a promising direction in liver fibrosis treatment. We discuss new perspectives of miRs and LncRNAs in liver fibrosis and HSC activation, mainly including interaction with histone modification or DNA methylation to regulate gene expression. These epigenetic mechanisms form powerful ncRNAs surveillance systems that may represent new targets for liver fibrosis therapeutic intervention.