Extracellular Vesicles From Hepatocytes Are Therapeutic for Toxin-Mediated Fibrosis and Gene Expression in the Liver.
ABSTRACT: Extracellular vesicles (EVs) are nano-sized membrane-limited organelles that are liberated from their producer cells, traverse the intercellular space, and may interact with other cells resulting in the uptake of the EV molecular payload by the recipient cells which may become functionally reprogramed as a result. Previous in vitro studies showed that EVs purified from normal mouse AML12 hepatocytes ("EVNorm") attenuate the pro-fibrogenic activities of activated hepatic stellate cells (HSCs), a principal fibrosis-producing cell type in the liver. In a 10-day CCl4 injury model, liver fibrogenesis, expression of hepatic cellular communication network factor 2 [CCN2, also known as connective tissue growth factor (CTGF)] or alpha smooth muscle actin (?SMA) was dose-dependently blocked during concurrent administration of EVNorm. Hepatic inflammation and expression of inflammatory cytokines were also reduced by EVNorm. In a 5-week CCl4 fibrosis model in mice, interstitial collagen deposition and mRNA and/or protein for collagen 1a1, ?SMA or CCN2 were suppressed following administration of EVNorm over the last 2 weeks. RNA sequencing (RNA-seq) revealed that EVNorm therapy of mice receiving CCl4 for 5 weeks resulted in significant differences [false discovery rate (FDR) <0.05] in expression of 233 CCl4-regulated hepatic genes and these were principally associated with fibrosis, cell cycle, cell division, signal transduction, extracellular matrix (ECM), heat shock, cytochromes, drug detoxification, adaptive immunity, and membrane trafficking. Selected gene candidates from these groups were verified by qRT-PCR as targets of EVNorm in CCl4-injured livers. Additionally, EVNorm administration resulted in reduced activation of p53, a predicted upstream regulator of 40% of the genes for which expression was altered by EVNorm following CCl4 liver injury. In vitro, EVs from human HepG2 hepatocytes suppressed fibrogenic gene expression in activated mouse HSC and reversed the reduced viability or proliferation of HepG2 cells or AML12 cells exposed to CCl4. Similarly, EVs produced by primary human hepatocytes (PHH) protected PHH or human LX2 HSC from CCl4-mediated changes in cell number or gene expression in vitro. These findings show that EVs from human or mouse hepatocytes regulate toxin-associated gene expression leading to therapeutic outcomes including suppression of fibrogenesis, hepatocyte damage, and/or inflammation.
Project description:The lack of approved therapies for hepatic fibrosis seriously limits medical management of patients with chronic liver disease. Since extracellular vesicles (EVs) function as conduits for intercellular molecular transfer, we investigated if EVs from healthy individuals have anti-fibrotic properties. Hepatic fibrogenesis or fibrosis in carbon tetrachloride (CCl4)- or thioacetic acid-induced liver injury models in male or female mice were suppressed by serum EVs from normal mice (EVN) but not from fibrotic mice (EVF). CCl4-treated mice undergoing EVN therapy also exhibited reduced levels of hepatocyte death, inflammatory infiltration, circulating AST/ALT levels and hepatic or circulating pro-inflammatory cytokines. Hepatic histology, liver function tests or circulating proinflammatory cytokine levels were unaltered in control mice receiving EVN. As determined using PKH26-labelled EVN, principal target cells included hepatic stellate cells (HSC; a normally quiescent fibroblastic cell that undergoes injury-induced activation and produces fibrosis during chronic injury) or hepatocytes which showed increased EVN binding after, respectively, activation or exposure to CCl4. In vitro, EVN decreased proliferation and fibrosis-associated molecule expression in activated HSC, while reversing the inhibitory effects of CCl4 or ethanol on hepatocyte proliferation. In mice, microRNA-34c, -151-3p, -483-5p, -532-5p and -687 were more highly expressed in EVN than EVF and mimics of these microRNAs (miRs) individually suppressed fibrogenic gene expression in activated HSC. A role for these miRs in contributing to EVN actions was shown by the ability of their corresponding antagomirs to individually and/or collectively block the therapeutic effects of EVN on activated HSC or injured hepatocytes. Similarly, the activated phenotype of human LX-2 HSC was attenuated by serum EVs from healthy human subjects and contained higher miR-34c, -151-3p, -483-5p or -532-5p than EVs from hepatic fibrosis patients. In conclusion, serum EVs from normal healthy individuals are inherently anti-fibrogenic and anti-fibrotic, and contain microRNAs that have therapeutic actions in activated HSC or injured hepatocytes. Abbreviations: ALT: alanine aminotransferase; AST: aspartate aminotransferase; CCl4: carbon tetrachloride; CCN2: connective tissue growth factor; E: eosin; EGFP: enhanced green fluorescent protein; EVs: extracellular vesicles; EVF: serum EVs from mice with experimental hepatic fibrosis; EVN: serum EVs from normal mice; H: hematoxylin; HSC: hepatic stellate cell; IHC: immunohistochemistry; IL: interleukin; MCP-1: monocyte chemotactic protein-1; miR: microRNA; mRNA: messenger RNA; NTA: nanoparticle tracking analysis; PCNA: proliferating cell nuclear antigen; qRT-PCR: quantitative real-time polymerase chain reaction; SDS-PAGE: sodium dodecyl sulphate - polyacrylamide gel electrophoresis; αSMA: alpha smooth muscle actin; TAA: thioacetic acid; TG: transgenic; TGF-β: transforming growth factor beta; TEM: transmission electron microscopy; TNFα: tumour necrosis factor alpha.
Project description:Liver fibrosis is characterized by changes in tissue architecture and extracellular matrix composition. Liver fibrosis affects not only hepatocytes but also the non-parenchymal cells such as hepatic stellate cells (HSCs), which are essential for maintaining an intact liver structure and function. Transforming growth factor ?1 (TGF-?1) is a multifunctional cytokine that induces liver fibrosis through activation of Smad signaling pathways. To improve a new therapeutic approach, synthetic TGF-?1/Smad oligodeoxynucleotide (ODN) was used to suppress both TGF-?1 expression and Smad transcription factor using a combination of antisense ODN and decoy ODN. The aims of this study are to investigate the anti-fibrotic effects of TGF-?1/Smad ODN on simultaneous suppressions of both Smad transcription factor and TGF-?1 mRNA expression in the hepatic fibrosis model in vitro and in vivo. Synthetic TGF-?1/Smad ODN effectively inhibits Smad binding activity and TGF-?1 expression. TGF-?1/Smad ODN attenuated the epithelial mesenchymal transition (EMT) and activation of HSCs in TGF-?1-induced AML12 and HSC-T6 cells. TGF-?1/Smad ODN prevented the fibrogenesis and deposition of collagen in CCl4-treated mouse model. Synthetic TGF-?1/Smad ODN demonstrates anti-fibrotic effects that are mediated by the suppression of fibrogenic protein and inflammatory cytokines. Therefore, synthetic TGF-?1/Smad ODN has substantial therapeutic feasibility for the treatment of liver fibrotic diseases.
Project description:: During chronic liver injury, hepatic stellate cells (HSC) undergo activation and are the principal cellular source of collagenous scar. In this study, we found that activation of mouse HSC (mHSC) was associated with a 4.5-fold increase in extracellular vesicle (EV) production and that fibrogenic gene expression (CCN2, Col1a1) was suppressed in Passage 1 (P1; activated) mHSC exposed to EVs from Day 4 (D4; relatively quiescent) mHSC but not to EVs from P1 mHSC. Conversely, gene expression (CCN2, Col1a1, ?SMA) in D4 mHSC was stimulated by EVs from P1 mHSC but not by EVs from D4 mHSC. EVs from Day 4 mHSC contained only 46 proteins in which histones and keratins predominated, while EVs from P1 mHSC contained 337 proteins and these were principally associated with extracellular spaces or matrix, proteasome, collagens, vesicular transport, metabolic enzymes, ribosomes and chaperones. EVs from the activated LX-2 human HSC (hHSC) line also promoted fibrogenic gene expression in D4 mHSC in vitro and contained 524 proteins, many of which shared identity or had functional overlap with those in P1 mHSC EVs. The activation-associated changes in production, function and protein content of EVs from HSC likely contribute to the regulation of HSC function in vivo and to the fine-tuning of fibrogenic pathways in the liver.
Project description:SerpinB3 is a hypoxia- and hypoxia-inducible factor-2?-dependent cystein protease inhibitor that is up-regulated in hepatocellular carcinoma and in parenchymal cells during chronic liver diseases (CLD). SerpinB3 up-regulation in CLD patients has been reported to correlate with the extent of liver fibrosis and the production of transforming growth factor-?1, but the actual role of SerpinB3 in hepatic fibrogenesis is still poorly characterized. In the present study we analyzed the pro-fibrogenic action of SerpinB3 in cell cultures and in two different murine models of liver fibrosis. "In vitro" experiments revealed that SerpinB3 addition to either primary cultures of human activated myofibroblast-like hepatic stellate cells (HSC/MFs) or human stellate cell line (LX2 cells) strongly up-regulated the expression of genes involved in fibrogenesis and promoted oriented migration, but not cell proliferation. Chronic liver injury by CCl4 administration or by feeding a methionine/choline deficient diet to transgenic mice over-expressing human SerpinB3 in hepatocytes confirmed that SerpinB3 over-expression significantly increased the mRNA levels of pro-fibrogenic genes, collagen deposition and ?SMA-positive HSC/MFs as compared to wild-type mice, without affecting parenchymal damage. The present study provides for the first time evidence that hepatocyte release of SerpinB3 during CLD can contribute to liver fibrogenesis by acting on HSC/MFs.
Project description:UNLABELLED:Connective tissue growth factor (CCN2) drives fibrogenesis in hepatic stellate cells (HSC). Here we show that CCN2 up-regulation in fibrotic or steatotic livers, or in culture-activated or ethanol-treated primary mouse HSC, is associated with a reciprocal down-regulation of microRNA-214 (miR-214). By using protector or reporter assays to investigate the 3'-untranslated region (UTR) of CCN2 mRNA, we found that induction of CCN2 expression in HSC by fibrosis-inducing stimuli was due to reduced expression of miR-214, which otherwise inhibited CCN2 expression by directly binding to the CCN2 3'-UTR. Additionally, miR-214 was present in HSC exosomes, which were bi-membrane vesicles, 50-150 nm in diameter, negatively charged (-26 mV), and positive for CD9. MiR-214 levels in exosomes but not in cell lysates were reduced by pretreatment of the cells with the exosome inhibitor, GW4869. Coculture of either quiescent HSC or miR-214-transfected activated HSC with CCN2 3'-UTR luciferase reporter-transfected recipient HSC resulted in miR-214- and exosome-dependent regulation of a wild-type CCN2 3'-UTR reporter but not of a mutant CCN2 3'-UTR reporter lacking the miR-214 binding site. Exosomes from HSC were a conduit for uptake of miR-214 by primary mouse hepatocytes. Down-regulation of CCN2 expression by miR-214 also occurred in human LX-2 HSC, consistent with a conserved miR-214 binding site in the human CCN2 3'-UTR. MiR-214 in LX-2 cells was shuttled by way of exosomes to recipient LX-2 cells or human HepG2 hepatocytes, resulting in suppression of CCN2 3'-UTR activity or expression of CCN2 downstream targets, including alpha smooth muscle actin or collagen. Experimental fibrosis in mice was associated with reduced circulating miR-214 levels. CONCLUSION:Exosomal transfer of miR-214 is a paradigm for the regulation of CCN2-dependent fibrogenesis and identifies fibrotic pathways as targets of intercellular regulation by exosomal miRs.
Project description:Transforming growth factor-? (TGF-?) is a potent cytokine that promotes the development of fibrogenic cells, stimulates the expression of fibrosis-related genes, and consequently results in hepatic fibrogenesis. The involvement of miRNAs in this process remains largely unknown. We showed that miR-122 was substantially expressed in hepatic stellate cells (HSCs) and fibroblasts, the major sources of fibrogenic cells in liver tissues. Notably, exposure to TGF-? led to significant downregulation of miR-122. Furthermore, reintroduction of miR-122 suppressed TGF-?-induced expression of fibrosis-related genes, including alpha smooth muscle actin (?-SMA), fibronectin 1 (FN1) and ?1 type I collagen (COL1A1), in HSCs and fibroblasts. Subsequent mechanism investigations revealed that miR-122 directly inhibited FN1 expression by binding to its 3'-untranslated region and indirectly reduced the transcription of ?-SMA and COL1A1 by inhibiting the expression of serum response factor (SRF), a key transcription factor that mediated the activation of fibrogenic cells. Further in vivo studies disclosed that intravenous injection of miR-122-expressing lentivirus successfully increased miR-122 level and reduced the amount of collagen fibrils, FN1 and SRF in the livers of CCl4-treated mice. These findings disclose a novel TGF-?-miR-122-FN1/SRF signaling cascade and its implication in hepatic fibrogenesis, and suggest miR-122 as a promising molecular target for anti-fibrosis therapy.
Project description:The liver-enriched transcription factor Forkhead Box A2 (FOXA2) has been reported to be involved in bile acid homeostasis and bile duct development. However, the role of FOXA2 in liver fibrogenesis remains undefined. In this study, we found that the abundance of FOXA2 was significantly lower in fibrotic livers of patients and mice treated with CCl4 than in controls. Interestingly, the expression level of FOXA2 decreased in hepatocytes, whereas FOXA2 was elevated in hepatic stellate cells (HSCs) of mouse fibrotic livers. Hepatocyte-specific ablation of FOXA2 in adult mice exacerbated liver fibrosis induced by CCl4. Either lentivirus LV-CMV-FOXA2 mediated FOXA2 overexpression in the liver or adeno-associated virus AAV8-TBG-FOXA2-mediated hepatocyte-specific upregulation of FOXA2 alleviated hepatic fibrosis. Overexpression of FOXA2 in HSCs did not obviously affect hepatic fibrogenesis. Additionally, FOXA2 knockout in hepatocytes resulted in aberrant transcription of metabolic genes. Furthermore, hepatocyte-specific knockout of FOXA2 enhanced endoplasmic reticulum stress (ER stress) and the apoptosis of hepatocytes, whereas FOXA2 overexpression in hepatocytes suppressed ER stress and hepatocyte apoptosis in mouse fibrotic livers. In conclusion, our findings suggested that FOXA2-mediated hepatocyte protection has a therapeutic role in hepatic fibrosis, and thus may be a new, promising anti-fibrotic option for treating chronic liver diseases.
Project description:The loss of mitochondrial function impairs intracellular energy production and potentially results in chronic liver disease. Increasing evidence suggests that mitochondrial dysfunction in hepatocytes contributes to the activation of hepatic stellate cells (HSCs), thereby resulting in hepatic fibrogenesis. High-temperature requirement protein A2 (HtrA2/Omi), a mitochondrial serine protease with various functions, is responsible for quality control in mitochondrial homeostasis. However, little information is available regarding its role in mitochondrial damage during the development of liver fibrosis. This study examined whether HtrA2/Omi regulates mitochondrial homeostasis in hepatocyte during the development of hepatic fibrogenesis. In this study, we demonstrated that HtrA2/Omi expression considerably decreased in liver tissues from the CCl4-induced liver fibrotic mice model and from patients with liver cirrhosis. Knockdown of HtrA2/Omi in hepatocytes induced the accumulation of damaged mitochondria and provoked mitochondrial reactive oxygen species (mtROS) stress. We further show that the damaged mtDNA isolated from HtrA2/Omi-deficient hepatocytes as a form of damage-associated molecular patterns can induce HSCs activation. Moreover, we found that motor neuron degeneration 2-mutant mice harboring the missense mutation Ser276Cys in the protease domain of HtrA2/Omi displayed altered mitochondrial morphology and function, which increased oxidative stress and promoted liver fibrosis. Conversely, the overexpression of HtrA2/Omi via hydrodynamics-based gene transfer led to the antifibrotic effects in CCl4-induced liver fibrosis mice model through decreasing collagen accumulation and enhancing anti-oxidative activity by modulating mitochondrial homeostasis in the liver. These results suggest that suppressing HtrA2/Omi expression promotes hepatic fibrogenesis via modulating mtROS generation, and these novel mechanistic insights involving the regulation of mitochondrial homeostasis by HtrA2/Omi may be of importance for developing new therapeutic strategies for hepatic fibrosis.
Project description:Background:There are no approved drug treatments for liver fibrosis and nonalcoholic steatohepatitis (NASH), an advanced stage of fibrosis which has rapidly become a major cause of cirrhosis. Therefore, development of anti-inflammatory and antifibrotic therapies is desired. Mesenchymal stem cell- (MSC-) based therapy, which has been extensively investigated in regenerative medicine for various organs, can reportedly achieve therapeutic effect in NASH via paracrine action. Extracellular vesicles (EVs) encompass a variety of vesicles released by cells that fulfill functions similar to those of MSCs. We herein investigated the therapeutic effects of EVs from amnion-derived MSCs (AMSCs) in rats with NASH and liver fibrosis. Methods:NASH was induced by a 4-week high-fat diet (HFD), and liver fibrosis was induced by intraperitoneal injection of 2?mL/kg 50% carbon tetrachloride (CCl4) twice a week for six weeks. AMSC-EVs were intravenously injected at weeks 3 and 4 in rats with NASH (15??g/kg) and at week 3 in rats with liver fibrosis (20??g/kg). The extent of inflammation and fibrosis was evaluated with quantitative reverse transcription polymerase chain reaction and immunohistochemistry. The effect of AMSC-EVs on inflammatory and fibrogenic response was investigated in vitro. Results:AMSC-EVs significantly decreased the number of Kupffer cells (KCs) in the liver of rats with NASH and the mRNA expression levels of inflammatory cytokines such as tumor necrosis factor- (Tnf-) ?, interleukin- (Il-) 1? and Il-6, and transforming growth factor- (Tgf-) ?. Furthermore, AMSC-EVs significantly decreased fiber accumulation, KC number, and hepatic stellate cell (HSC) activation in rats with liver fibrosis. In vitro, AMSC-EVs significantly inhibited KC and HSC activation and suppressed the lipopolysaccharide (LPS)/toll-like receptor 4 (TLR4) signaling pathway. Conclusions:AMSC-EVs ameliorated inflammation and fibrogenesis in a rat model of NASH and liver fibrosis, potentially by attenuating HSC and KC activation. AMSC-EV administration should be considered as a new therapeutic strategy for chronic liver disease.
Project description:The pathogenesis of liver fibrosis involves activation of hepatic stellate cells, which is associated with depletion of intracellular lipid droplets. When hepatocytes undergo autophagy, intracellular lipids are degraded in lysosomes. We investigated whether autophagy also promotes loss of lipids in hepatic stellate cells to provide energy for their activation and extended these findings to other fibrogenic cells.We analyzed hepatic stellate cells from C57BL/6 wild-type, Atg7(F/F), and Atg7(F/F)-GFAP-Cre mice, as well as the mouse stellate cell line JS1. Fibrosis was induced in mice using CCl(4) or thioacetamide (TAA); liver tissues and stellate cells were analyzed. Autophagy was blocked in fibrogenic cells from liver and other tissues using small interfering RNAs against Atg5 or Atg7 and chemical antagonists. Human pulmonary fibroblasts were isolated from samples of lung tissue from patients with idiopathic pulmonary fibrosis or from healthy donors.In mice, induction of liver injury with CCl(4) or TAA increased levels of autophagy. We also observed features of autophagy in activated stellate cells within injured human liver tissue. Loss of autophagic function in cultured mouse stellate cells and in mice following injury reduced fibrogenesis and matrix accumulation; this effect was partially overcome by providing oleic acid as an energy substrate. Autophagy also regulated expression of fibrogenic genes in embryonic, lung, and renal fibroblasts.Autophagy of activated stellate cells is required for hepatic fibrogenesis in mice. Selective reduction of autophagic activity in fibrogenic cells in liver and other tissues might be used to treat patients with fibrotic diseases.