CDH11 promotes liver fibrosis via activation of hepatic stellate cells

Liver fibrosis, an important health condition associated with chronic liver injury that provides a permissive environment for cancer development, is characterized by the persistent deposition of extracellular matrix components that are mainly derived from activated hepatic stellate cells (HSCs). CDH11 belongs to a group of transmembrane proteins that are principally located in adherens junctions. CDH11 mediates homophilic cell-to-cell adhesion, which may promote the development of cirrhosis. The goal of this study was to determine whether CDH11 regulates liver fibrosis and to examine its mechanism by focusing on HSC activation. Here we demonstrate that CDH11 expression is elevated in human and mouse fibrotic liver tissues and that CDH11 mediates the profibrotic response in activated HSCs. Our data indicate that CDH11 regulates the TGFβ-induced activation of HSCs. Moreover, cells from CDH11 deficient mice displayed decreased HSC activation in vitro, and CDH11 deficient mice developed liver fibrogenesis in response to chronic damage induced by CCl₄ administration. In addition, CDH11 expression was positively correlated with liver fibrosis in patients with cirrhosis, and could therefore be a prognostic factor in patients with liver fibrosis. Collectively, our findings demonstrate that CDH11 promotes liver fibrosis by activating HSCs and may represent a potential target for anti-fibrotic therapies.     

Serum-derived miR-574-5p-containing exosomes contribute to liver fibrosis by activating hepatic stellate cells

Molecular Biology Reports - To investigate the association of serum exosomes miR-574-5p with liver fibrosis, and explore the effect and mechanism of serum exosomes on HSC activation. Using serum...     

Addressing liver fibrosis with liposomes targeted to hepatic stellate cells

Liver fibrosis is a chronic disease that results from hepatitis B and C infections, alcohol abuse or metabolic and genetic disorders. Ultimately, progression of fibrosis leads to cirrhosis, a stage of the disease characterized by failure of the normal liver functions. Currently, the treatment of liver fibrosis is mainly based on the removal of the underlying cause of the disease and liver transplantation, which is the only treatment for patients with advanced fibrosis. Hepatic stellate cells (HSC) are considered to be key players in the development of liver fibrosis. Chronically activated HSC produces large amounts of extracellular matrix and enhance fibrosis by secreting a broad spectrum of cytokines that exert pro-fibrotic actions in other cells, and in an autocrine manner perpetuate their own activation. Therefore, therapeutic interventions that inhibit activation of HSC and its pro-fibrotic activities are currently under investigation worldwide. In the present study we applied targeted liposomes as drug carriers to HSC in the fibrotic liver and explored the potential of these liposomes in antifibrotic therapies. Moreover, we investigated effects of bioactive compounds delivered by these liposomes on the progression of liver fibrosis. To our knowledge, this is the first study demonstrating that lipid-based drug carriers can be selectively delivered to HSC in the fibrotic liver. By incorporating the bioactive lipid DLPC, these liposomes can modulate different processes such as inflammation and fibrogenesis in the fibrotic liver. This dual functionality of liposomes as a drug carrier system with intrinsic biological effects may be exploited in new approaches to treat liver fibrosis.     

MyD88 in hepatic stellate cells enhances liver fibrosis via promoting macrophage M1 polarization

During liver fibrosis, quiescent HSCs (qHSCs) are activated to become activated HSCs (aHSCs)/myofibroblasts. The signal adapter MyD88, an essential component of TLR signaling, plays an important role in liver fibrosis. However, far less is known about the specific effects of MyD88 signaling in both qHSCs and aHSCs in the progress of liver fibrosis. Here, we used a CCl₄-induced mouse fibrosis model in which MyD88 was selectively depleted in qHSCs (GFAP^MyD88−/− mice) or aHSCs (α-SMA^MyD88−/− mice). MyD88 deficiency in qHSCs or aHSCs attenuated liver fibrosis in mice and inhibited α-SMA-positive cell activation. Inhibition of MyD88 in HSCs decreased α-SMA and collagen I levels, inflammatory cell infiltration, and pro-inflammatory gene expression. Furthermore, MyD88 signaling in HSCs increased the secretion of CXCL10, which promoted macrophage M1 polarization through CXCR3, leading to activation of the JAK/STAT1 pathway. Inhibition of CXCL10 attenuated macrophage M1 polarization and reduced liver fibrosis. Thus, MyD88 signaling in HSCs crucially contributes to liver fibrosis and provides a promising therapeutic target for the prevention and treatment of liver fibrosis.Subject terms: Mechanisms of disease, Kupffer cells     

Overexpression of c-myc in hepatocytes promotes activation of hepatic stellate cells and facilitates the onset of liver fibrosis

BackgroundLiver fibrosis is a consequence of chronic liver injury and can further progress to hepatocellular carcinoma (HCC). Fibrogenesis involves activation of hepatic stellate cells (HSC) and proliferation of hepatocytes upon liver injury. HCC is frequently associated with overexpression of the proto-oncogene c-myc. However, the impact of c-myc for initiating pathological precursor stages such as liver fibrosis is poorly characterized. In the present study we thus investigated the impact of c-myc for liver fibrogenesis.MethodsExpression of c-myc was measured in biopsies of patients with liver fibrosis of different etiologies by quantitative real-time PCR (qPCR). Primary HSC were isolated from mice with transgenic overexpression of c-myc in hepatocytes (alb-myc^tg) and wildtype (WT) controls and investigated for markers of cell cycle progression and fibrosis by qPCR and immunofluorescence microscopy. Liver fibrosis in WT and alb-myc^tg mice was induced by repetitive CCl₄ treatment.ResultsWe detected strong up-regulation of hepatic c-myc in patients with advanced liver fibrosis. In return, overexpression of c-myc in alb-myc^tg mice resulted in increased liver collagen deposition and induction of α-smooth-muscle-actin indicating HSC activation. Primary HSC derived from alb-myc^tg mice showed enhanced proliferation and accelerated transdifferentiation into myofibroblasts in vitro. Accordingly, fibrosis initiation in vivo after chronic CCl₄ treatment was accelerated in alb-myc^tg mice compared to controls.ConclusionOverexpression of c-myc is a novel marker of liver fibrosis in man and mice. We conclude that chronic induction of c-myc especially in hepatocytes has the potential to prime resident HSC for activation, proliferation and myofibroblast differentiation.     

TIMP-1和肝星状细胞对肝纤维化的影响

肝纤维化是慢性肝病向肝硬化发展的必经之路,是细胞外基(Extracellular matrix,ECM)在肝内过多沉积所致。ECM主要由激活的肝星状细胞(Hepatic stellate cell,HSC)合成,同时它的降解受到基质金属蛋白酶组织抑制剂-1(Tissue inhibitor of metal protease-1,TIMP-1)的调控,因此HSC及TIMP-1对肝纤维化形成至关重要。近年来针对HSC及TIMP-1抗肝纤维化的研究已成为热点,就HSC及TIMP-1的生物学特性及其对肝纤维化的作用作一综述。     

Curcumin attenuates angiogenesis in liver fibrosis and inhibits angiogenic properties of hepatic stellate cells

Hepatic fibrosis is concomitant with sinusoidal pathological angiogenesis, which has been highlighted as novel therapeutic targets for the treatment of chronic liver disease. Our prior studies have demonstrated that curcumin has potent antifibrotic activity, but the mechanisms remain to be elucidated. The current work demonstrated that curcumin ameliorated fibrotic injury and sinusoidal angiogenesis in rat liver with fibrosis caused by carbon tetrachloride. Curcumin reduced the expression of a number of angiogenic markers in fibrotic liver. Experiments in vitro showed that the viability and vascularization of rat liver sinusoidal endothelial cells and rat aortic ring angiogenesis were not impaired by curcumin. These results indicated that hepatic stellate cells (HSCs) that are characterized as liver‐specific pericytes could be potential target cells for curcumin. Further investigations showed that curcumin inhibited VEGF expression in HSCs associated with disrupting platelet‐derived growth factor‐β receptor (PDGF‐βR)/ERK and mTOR pathways. HSC motility and vascularization were also suppressed by curcumin associated with blocking PDGF‐βR/focal adhesion kinase/RhoA cascade. Gain‐ or loss‐of‐function analyses revealed that activation of peroxisome proliferator‐activated receptor‐γ (PPAR‐γ) was required for curcumin to inhibit angiogenic properties of HSCs. We concluded that curcumin attenuated sinusoidal angiogenesis in liver fibrosis possibly by targeting HSCs via a PPAR‐γ activation‐dependent mechanism. PPAR‐γ could be a target molecule for reducing pathological angiogenesis during liver fibrosis.     

Senescence of activated stellate cells limits liver fibrosis

Cellular senescence acts as a potent mechanism of tumor suppression; however, its functional contribution to noncancer pathologies has not been examined. Here we show that senescent cells accumulate in murine livers treated to produce fibrosis, a precursor pathology to cirrhosis. The senescent cells are derived primarily from activated hepatic stellate cells, which initially proliferate in response to liver damage and produce the extracellular matrix deposited in the fibrotic scar. In mice lacking key senescence regulators, stellate cells continue to proliferate, leading to excessive liver fibrosis. Furthermore, senescent activated stellate cells exhibit gene expression profile consistent with cell-cycle exit, reduced secretion of extracellular matrix components, enhanced secretion of extracellular matrix-degrading enzymes, and enhanced immune surveillance. Accordingly natural killer cells preferentially kill senescent activated stellate cells in vitro and in vivo, thereby facilitating the resolution of fibrosis. Therefore, the senescence program limits the fibrogenic response to acute tissue damage.     

TWEAK promotes hepatic stellate cell migration through activating EGFR/Src and PI3K/AKT pathways

Activated human hepatic stellate cells (HSCs) showed enhanced ability of migration compared with quiescent HSCs, which is pivotal in liver fibrogenesis. The aim of the present study was to investigate the effects of tumor necrosis factor‐like weak inducer of apoptosis (TWEAK) on the migration of activated HSCs and to explore the relevant potential mechanisms. Human HSCs LX‐2 cells were cultured with TWEAK. TNFRSF12A‐downexpressing lentiviruses were used to infect LX‐2 cells. The specific matrix metalloproteinases inhibitor BB94, the Src family kinase inhibitor, Dasatinib, and the specific inhibitor of phosphoinositide 3‐kinase (PI3K), LY294002 were used to treat LX‐2 cells combined with TWEAK. Cell migration and invasion was tested by the transwell assay. The expression of EGFR/Src, PI3K/AKT, and matrix metallopeptidase 9 (MMP9) was identified by real‐time polymerase chain reaction or western blotting. The result showed TWEAK promoted HSC migration and collagen production. BB94 significantly attenuated the migration of LX‐2 induced by TWEAK. Dasatinib inhibited the ability of cell migration stimulated by TWEAK. TWEAK upregulated the phosphorylation of epidermal growth factor receptor (EGFR) and Src. The phosphorylation of PI3K and AKT was significantly activated by TWEAK stimulation. Inhibition of PI3K/AKT reduced the expression of MMP9 induced by TWEAK. The present study, for the first time, demonstrated that TWEAK promoted HSC migration through the activation of EGFR/Src and PI3K/AKT pathways, and showed a novel potential mechanism of HSC migration regulated by TWEAK.     

核受体FXR在肝星状细胞及肝纤维化中的作用

法尼醇X受体(farnesoid X receptor,FXR)是核受体超家族的重要成员,以作为胆汁酸受体被大家所熟知.除了调节胆汁酸的合成和转运,FXR在调控葡萄糖代谢、甘油三酯代谢、炎症、凝血等方面也发挥重要作用.肝纤维化是慢性肝脏疾病发展成肝硬化的共同途径,终末期肝纤维化将导致肝硬化、肝衰竭,甚至危及生命.肝星状...     

Differential fibrotic phenotypes of hepatic stellate cells within 3D liver organoids

Liver fibrosis occurs in most cases of chronic liver disease, which are somewhat common, but also a potentially deadly group of diseases. In vitro modeling of liver fibrosis relies primarily on the isolation of in vivo activated hepatic stellate cells (aHSCs) and studying them in standard tissue culture dishes (two-dimensional [2D]). In contrast, modeling of fibrosis in a biofabricated three-dimensional (3D) construct allows us to study changes to the environment, such as extracellular matrix (ECM) composition and structure, and tissue rigidity. In the current study, we used aHSCs produced through subcultures in 2D and encapsulated them in a 3D collagen gel to form spherical constructs. In parallel, and as a comparison, we used an established HSC line, LX-2, representing early and less severe fibrosis. Compared with LX-2 cells, the aHSCs created a stiffer environment and expressed higher levels of TIMP1 and LOXL2, all of which are indicative of advanced liver fibrosis. Collectively, this study presents a fibrosis model that could be incorporated with multi-cellular models to more accurately reflect the effects of a severe fibrotic environment on liver function.     

Soluble TREM-1, as a new ligand for the membrane receptor Robo2, promotes hepatic stellate cells activation and liver fibrosis

Triggering receptor expressed on myeloid cells-1 (TREM-1) exists in two forms: a transmembrane form and a soluble form (sTREM-1). The levels of sTREM-1 are elevated in supernatants of activated HSCs. However, the role of sTREM-1 in HSC activation and liver fibrosis remains undefined. Previous studies have primarily focused on the transmembrane form of TREM-1; we innovatively observed the function of sTREM-1 as a ligand in liver fibrosis and screened its receptor. Here, recombinant sTREM-1 was used as a stimulator which induced HSC activation and further aggravated liver fibrosis. Then, screening for sTREM-1 interacting membrane receptors was performed using pull-down assay followed by mass spectrometry, and the membrane receptor roundabout guidance receptor 2 (Robo2) was identified as a candidate receptor for sTREM-1. The interaction between sTREM-1 and Robo2 was verified by pull-down and immunofluorescence. The role of Robo2 on sTREM-1-induced HSC activation and its downstream signal pathways was assessed by knockdown of Robo2 in LX-2 cells. Furthermore, HSC-specific knockdown of Robo2 was achieved in a mouse model of liver fibrosis by using a recombinant adeno-associated virus (AAV) vector to confirm the role of the receptor, and we proved that Robo2 knockdown inhibited the activation of HSC and liver fibrosis, which also led to the inactivation of Smad2/3 and PI3K/Akt pathways in sTREM-1-induced HSC activation and liver fibrosis. In conclusion, sTREM-1 acts as a new ligand of Robo2; the binding of sTREM-1 to Robo2 initiates the activation of the downstream Smad2/3 and PI3K/Akt signalling pathways, thereby promoting HSC activation and liver fibrosis.