基质金属蛋白酶及其抑制剂在肝纤维化中的表达变化

目的 观察肝纤维化形成过程中基质金属蛋白酶MMP-1及其抑制剂TIMP-1的表达变化,从细胞外基质降解代谢的角度研究四氯化碳(CCl4)中毒性肝纤维化发生的机制.方法 雄性Wistar大鼠20只,分为正常组和肝纤维化模型组.肝纤维化组采用CCl4、饮酒、高脂低蛋白饮食等复合病因刺激制备肝纤维化动物模型,造模时间为8周.实验结束后测定肝脏指数、血清透明质酸(HA)、谷丙转氨酶(ALT)及尿羟脯氨酸(HYP)排出量,光镜下观察肝组织纤维化程度,并用免疫组化SABC法检测肝组织中Ⅰ、Ⅲ型胶原蛋白及MMP-1、TIMP-1的表达,同时用荧光实时定量PCR(RT-PCR)的方法检测肝组织中MMP-1、TIMP-1 mRNA的表达.结果 与正常对照组比较,肝纤维化模型组大鼠肝脏指数、血清HA及ALT显著增高,尿羟脯氨酸的排出量明显增加,病理组织学检查发现肝组织内纤维结缔组织增生明显,有假小叶形成;免疫组化的结果显示肝组织内Ⅰ、Ⅲ型胶原蛋白、MMP-1及TIMP-1的表达较正常组显著增加.结论 肝组织中MMP-1及TIMP-1的表达变化可能是导致肝纤维化的重要机制之一.     

Myocardial Fibrosis Induced by Exposure to Subclinical Lipopolysaccharide Is Associated with Decreased miR-29c and Enhanced NOX2 Expression in Mice

Background

Exposure to subclinical levels of lipopolysaccharide (LPS) occurs commonly and is seemingly well tolerated. However, recurrent LPS exposure induces cardiac fibrosis over 2 to 3 months in a murine model, not mediated by the renin-angiotensin system. Subclinical LPS induces cardiac fibrosis by unique mechanisms.

Methods

In C57/Bl6 mice, LPS (10 mg/kg) or saline (control) were injected intraperitoneally once a week for 1–4 weeks. Mice showed no signs of distress, change in activity, appetite, or weight loss. Mice were euthanized after 3 days, 1, 2, or 4 weeks to measure cardiac expression of fibrosis-related genes and potential mediators (measured by QRT-PCR), including micro-RNA (miR) and NADPH oxidase (NOX). Collagen fraction area of the left ventricle was measured with picrosirius red staining. Cardiac fibroblasts isolated from adult mouse hearts were incubated with 0, 0.1, 1.0 or 10 ng/ml LPS for 48 hours.

Results

Cardiac miR expression profiling demonstrated decreased miR-29c after 3 and 7 days following LPS, which were confirmed by QRT-PCR. The earliest changes in fibrosis-related genes and mediators that occurred 3 days after LPS were increased cardiac expression of TIMP-1 and NOX-2 (but not of NOX-4). This persisted at 1 and 2 weeks, with additional increases in collagen Iα1, collagen IIIα1, MMP2, MMP9, TIMP1, TIMP2, and periostin. There was no change in TGF-β or connective tissue growth factor. Collagen fraction area of the left ventricle increased after 2 and 4 weeks of LPS. LPS decreased miR-29c and increased NOX-2 in isolated cardiac fibroblasts.

Conclusions

Recurrent exposure to subclinical LPS induces cardiac fibrosis after 2–4 weeks. Early changes 3 days after LPS were decreased miR-29c and increased NOX2 and TIMP1, which persisted at 1 and 2 weeks, along with widespread activation of fibrosis-related genes. Decreased miR-29c and increased NOX2, which induce cardiac fibrosis in other conditions, may uniquely mediate LPS-induced cardiac fibrosis.     

Combined effects of an antioxidant and caspase inhibitor on the reversal of hepatic fibrosis in rats

We sought to determine the hepatic fibrosis-reversal effects upon simultaneous administration of lithospermate B (LAB), an anti-oxidant, and nivocasan, a caspase inhibitor, to rats compared with each compound alone. Liver fibrosis was induced in Sprague–Dawley rats by thioacetamide (TAA). Rats were treated with TAA and then given LAB and (or) nivocasan. Fibrotic areas were evaluated quantitatively by computerized morphometry. Apoptosis was assessed using a TUNEL assay, and immunohistochemical staining for malondialdehyde (MDA) and 4-hydroxy-2-nonenal (4HNE) was performed to assess oxidative stress levels. Real-time quantitative PCR was used to quantify expression of fibrosis-related genes. The degree of hepatic fibrosis was significantly reduced in rats treated with LAB and nivocasan compared to either treatment alone (P < 0.001). Treatment with each compound significantly decreased expression of fibrosis-related genes, such as type I collagen α1 (col1α1), α-SMA and TGF-β1 (P < 0.05). Co-treatment with LAB and nivocasan further reduced col1α1 expression compared to treatment with either compound. A TUNEL assay revealed that hepatocyte apoptosis was significantly decreased in the group treated with nivocasan compared to other groups (P < 0.01). Immunohistochemistry showed a decrease in MDA and 4HNE, reflecting amelioration of oxidative stress, when LAB or LAB+nivocasan was administered compared to nivocasan alone (P < 0.01). Nivocasan was found to inhibit caspase-1, -3, -7, -9 and gliotoxin-induced death of rat-derived hepatic stellate cells was inhibited by nivocasan administration without overexpression of α-SMA. Conclusions: Co-incidental administration of LAB and nivocasan suppressed oxidative stress and apoptosis, resulting in enhanced reversal of hepatic fibrosis in rat.     

Elucidation of the role of COX-2 in liver fibrogenesis using transgenic mice

Hepatic COX-2 overexpression is sufficient to induce hepatitis, but its role on liver fibrosis remains unknown. We aim to elucidate possible biological effects of COX-2 in liver fibrosis using both gain-of-function and loss-of-function mouse models. COX-2 transgenic (TG) mice that specifically overexpress the human COX-2 cDNA in the liver, knockout (KO), and wild type (WT) mice were studied in two different murine fibrosis models induced by carbon tetrachloride (CCl₄) injection or methionine and choline-deficient (MCD) diet. Liver injury was assessed by serum ALT and bilirubin levels and histological examination. Hepatic collagen content was determined by picrosirius red stain morphometry assay and quantitation of hydroxyproline. Hepatic stellate cell (HSC) activation was determined by immunohistochemical analysis of α-smooth muscle actin (α-SMA). mRNA expression of fibrogenic genes was assayed by real-time quantitative PCR. COX-2 protein was overexpressed in the liver of TG mice compared with WT littermates. CCl₄ or MCD-induced liver fibrotic injury was equally severe in TG and WT mice, as demonstrated by similar elevated levels of hepatic collagen contents. Enhanced COX-2 expression in TG liver did not affect HSC activation and fibrogenic gene expression upon CCl₄ or MCD treatment. Importantly, CCl₄-treated KO mice did not show significant difference in liver fibrotic damage and fibrogenic gene expression compared with the WT counterparts. This is the first report on the effect of COX-2 in liver fibrosis based on genetic mouse models. The results suggest that COX-2 does not appear to mediate the development of liver fibrosis.     

Aldehyde dehydrogenase 2 activation ameliorates CCl4‐induced chronic liver fibrosis in mice by up‐regulating Nrf2/HO‐1 antioxidant pathway

Mitochondrial aldehyde dehydrogenase 2 (ALDH2) is critical in the pathogenesis of alcoholic liver cirrhosis. However, the effect of ALHD2 on liver fibrosis remains to be further elucidated. This study aimed to demonstrate whether ALDH2 regulates carbon tetrachloride (CCl₄)‐induced liver fibrosis and to investigate the efficacy of Alda‐1, a specific activator of ALDH2, on attenuating liver fibrosis. ALDH2 expression was increased after chronic CCl₄ exposure. ALDH2 deficiency accentuated CCl₄‐induced liver fibrosis in mice, accompanied by increased expression of collagen 1α1, α‐SMA and TIMP‐1. Moreover, ALDH2 knockout triggered more ROS generation, hepatocyte apoptosis and impaired mitophagy after CCl₄ treatment. In cultured HSC‐T6 cells, ALDH2 knockdown by transfecting with lentivirus vector increased ROS generation and α‐SMA expression in an in vitro hepatocyte fibrosis model using TGF‐β1. ALDH2 overexpression by lentivirus or activation by Alda‐1 administration partly reversed the effect of TGF‐β1, whereas ALDH2 knockdown totally blocked the protective effect of Alda‐1. Furthermore, Alda‐1 administration protected against liver fibrosis in vivo, which might be mediated through up‐regulation of Nrf2/HO‐1 cascade and activation of Parkin‐related mitophagy. These findings indicate that ALDH2 deficiency aggravated CCl₄‐induced hepatic fibrosis through ROS overproduction, increased apoptosis and mitochondrial damage, whereas ALDH2 activation through Alda‐1 administration alleviated hepatic fibrosis partly through activation of the Nrf2/HO‐1 antioxidant pathway and Parkin‐related mitophagy, which indicate ALDH2 as a promising anti‐fibrotic target and Alda‐1 as a potential therapeutic agent in treating CCl₄‐induced liver fibrosis.     

New insight into the antifibrotic effects of praziquantel on mice in infection with Schistosoma japonicum

Background

Schistosomiasis is a parasitic disease infecting more than 200 million people in the world. Although chemotherapy targeting on killing schistosomes is one of the main strategies in the disease control, there are few effective ways of dealing with liver fibrosis caused by the parasite infection in the chronic and advanced stages of schistosomiasis. For this reason, new strategies and prospective drugs, which exert antifibrotic effects, are urgently required.

Methods and Findings

The antifibrotic effects of praziquantel were assessed in the murine models of schistosomiasis japonica. Murine fibrosis models were established by cutaneous infection with 14±2 Schistosoma japonicum cercariae. Then, the mice of both chronic (8 weeks post-infection) and advanced (15 weeks post-infection) schistosomiasis were treated by gavage of praziquantel (250 mg/kg, once daily for 3 days) to eliminate worms, and followed by praziquantel anti-fibrosis treatment (300 mg/kg, twice daily for 30 days). The fibrosis-related parameters assessed were areas of collagen deposition, content of hydroxyproline and mRNA expressions of Col1α1, Col3α1, α-SMA, TGF-β, MMP9, TIMP1, IL-4, IL-10, IL-13 and IFN-γ of liver. Spleen weight index, alanine aminotransferase activity and liver portal venous pressure were also measured. The results showed that anti-fibrosis treatment improved liver fibrosis, splenomegaly, hepatic function, as well as liver portal hypertension. In order to confirm the anti-fibrotic properties of praziquantel, we established a CCL₄-induced model and revealed that CCL₄-induced liver fibrosis was inhibited by PZQ treatment for 30 days. Furthermore, we analyzed the effects of praziquantel on mouse primary hepatic stellate cells (HSCs). It is indicated that mRNA expressions of Col1α1, Col3α1, α-SMA, TGF-β, MMP9 and TIMP1 of HSCs were all inhibited after praziquantel anti-parasite treatments.

Conclusions

The significant amelioration of hepatic fibrosis by praziquantel treatment validates it as a promising drug of anti-fibrosis and offers potential of a new chemotherapy for hepatic fibrosis resulting from schistosomiasis.     

Ascorbic acid supplementation down-regulates the alcohol induced oxidative stress, hepatic stellate cell activation, cytotoxicity and mRNA levels of selected fibrotic genes in guinea pigs

Both oxidative stress and endotoxins mediated immunological reactions play a major role in the progression of alcoholic hepatic fibrosis. Ascorbic acid has been reported to reduce alcohol-induced toxicity and ascorbic acid levels are reduced in alcoholics. Hence, we investigated the hepatoprotective action of ascorbic acid in the reversal of alcohol-induced hepatic fibrosis in male guinea pigs (n = 36), and it was compared with the animals abstenting from alcohol treatment. In comparison with the alcohol abstention group, there was a reduction in the activities of toxicity markers and levels of lipid and protein peroxidation products, expression of α-SMA, caspase-3 activity and mRNA levels of CYP2E1, TGF-β(1), TNF-α and α(1)(I) collagen in liver of the ascorbic acid-supplemented group. The ascorbic acid content in liver was significantly reduced in the alcohol-treated guinea pigs. But it was reversed to normal level in the ascorbic acid-supplemented group. The anti-fibrotic action of ascorbic acid in the rapid regression of alcoholic liver fibrosis may be attributed to decrease in the oxidative stress, hepatic stellate cells activation, cytotoxicity and mRNA expression of fibrotic genes CYP2E1, TGF-β(1), TNF-α and α(1) (I) collagen in hepatic tissues.     

Antagonizing TGF-beta induced liver fibrosis by a retinoic acid derivative through regulation of ROS and calcium influx

Transforming growth factor-beta1 (TGF-β1) mediates the regulation of extracellular matrix via reactive oxygen species (ROS) and calcium influx, both are activators of hepatic stellate cells (HSC) which play a critical role in hepatic fibrogenesis. Hence one can use ROS assay as the main screening tool for molecules that might antagonize the process of liver fibrosis. A retinoic acid derivative isolated from the mycelium of Phellinus linteus that down-regulates ROS generation and calcium influx in HSC-T6 cells was thus obtained in our screening process. The retinoic acid derivative also reverses an early liver fibrosis, as assayed by liver contents of hydroxyproline, α-smooth muscle actin (α-SMA), and collagen 1A2, in an early liver fibrosis model we established previously where an inducible expression vector containing a TGF-β gene was hydrodynamically transferred into a testing animal. Retinoic acid derivative thus acts both in vitro and in vivo to prevent liver fibrosis at an early phase.     

Ascorbic acid supplementation down-regulates the alcohol induced oxidative stress,hepatic stellate cell activation,cytotoxicity and mRNA levels of selected fibrotic genes in guinea pigs

Both oxidative stress and endotoxins mediated immunological reactions play a major role in the progression of alcoholic hepatic fibrosis. Ascorbic acid has been reported to reduce alcohol-induced toxicity and ascorbic acid levels are reduced in alcoholics. Hence, we investigated the hepatoprotective action of ascorbic acid in the reversal of alcohol-induced hepatic fibrosis in male guinea pigs (n = 36), and it was compared with the animals abstenting from alcohol treatment. In comparison with the alcohol abstention group, there was a reduction in the activities of toxicity markers and levels of lipid and protein peroxidation products, expression of α-SMA, caspase-3 activity and mRNA levels of CYP2E1, TGF-β₁, TNF-α and α₁(I) collagen in liver of the ascorbic acid-supplemented group. The ascorbic acid content in liver was significantly reduced in the alcohol-treated guinea pigs. But it was reversed to normal level in the ascorbic acid-supplemented group. The anti-fibrotic action of ascorbic acid in the rapid regression of alcoholic liver fibrosis may be attributed to decrease in the oxidative stress, hepatic stellate cells activation, cytotoxicity and mRNA expression of fibrotic genes CYP2E1, TGF-β₁, TNF-α and α₁ (I) collagen in hepatic tissues.     

大鼠肝纤维化过程中组织金属蛋白酶抑制因子I基因的原位表达

为了解组织金属蛋白酶抑制因子１（ＴＩＭＰ－１）基因在实验性肝纤维化形成中的作用,我们应用地高辛原位杂交技术对大鼠肝组织在四氯化碳（ＣＣｌ４）诱发肝纤维化形成过程中ＴＩＭＰ－１ｍＲ－ＮＡ的表达进行了研究。结果表明,ＣＣｌ４肝损伤早期（４周）肝组织中间质细胞（血管及窦内皮细胞及贮脂细胞）中显示ＴＩＭＰ－１的过度表达;ＣＣｌ４肝纤维化早期（８周）及肝纤维化晚期（１２周）,肝组织中间质细胞的ＴＩＭＰ－１表达持续维持在高水平。结果提示,肝间质细胞（内皮细胞及贮脂细胞）是肝内ＴＩＭＰ－１的主要来源细胞;ＴＩＭＰ－１的异常表达是大鼠肝纤维化过程中较早出现的分子变化,与肝纤维化发生有关;纤维化晚期持续高表达的ＴＩＭＰ－１通过抑制胶原酶而在肝纤维化持续进展中起重要作用。     

Reduced hepatic injury in Toll-like receptor 4-deficient mice following D-galactosamine/lipopolysaccharide-induced fulminant hepatic failure

Liver transplantation is the only therapy of proven benefit in fulminant hepatic failure (FHF). Lipopolysaccharide (LPS), D-galactosamine (GalN)-induced FHF is a well established model of liver injury in mice. Toll-Like Receptor 4 (TLR4) has been identified as a receptor for LPS. The aim of this study was to investigate the role of TLR4 in FHF induced by D-GalN/LPS administration in mice. Wild type (WT) and TLR4 deficient (TLR4ko) mice were studied in vivo in a fulminant model induced by GalN/LPS. Hepatic TLR4 expression, serum liver enzymes, hepatic and serum TNF-α and interleukin-1β levels were determined. Apoptotic cells were identified by immunohistochemistry for caspase-3. Nuclear factor-kappaβ (NF-κ β) and phosphorylated c-Jun hepatic expression were studied using Western blot analysis. All WT mice died within 24 hours after administration of GalN/LPS while all TLR4ko mice survived. Serum liver enzymes, interleukin-1β, TNF-α level, TLR4 mRNA expression, hepatic injury and hepatocyte apoptosis all significantly decreased in TLR4ko mice compared with WT mice. A significant decrease in hepatic c-Jun and IκB signaling pathway was noted in TLR4ko mice compared with WT mice. In conclusion, following induction of FHF, the inflammatory response and the liver injury in TLR4ko mice was significantly attenuated through decreased hepatic c-Jun and NF-κB expression and thus decreased TNF-α level. Down-regulation of TLR4 expression plays a pivotal role in GalN/LPS induced FHF. These findings might have important implications for the use of the anti TLR4 protein signaling as a potential target for therapeutic intervention in FHF.     

Melatonin ameliorates carbon tetrachloride-induced hepatic fibrogenesis in rats via inhibition of oxidative stress

Melatonin is reported to exhibit a wide variety of biological effects, including antioxidant and anti-inflammatory. Evidence shows the important role of oxidative stress in the etiopathogenesis of hepatic fibrosis. The aim of this study was to investigate the protective effects of administration of melatonin in rats with carbon tetrachloride-induced fibrosis for 6 weeks. Hepatic fibrotic changes were evaluated biochemically by measuring tissue hydroxyproline levels and histopathogical examinations. Malondialdehyde (MDA), an end product of lipid peroxidation, and glutathione peroxidase (GSH-px) and superoxide dismutase (SOD) levels were evaluated in tissue homogenates by spectrophotometry. The nuclear factor-kappaB (NF-kappaB) in liver tissue was examined by immunohistochemistry. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) concentrations in Kupffer cells (KCs) culture supernatants were measured with ELISA. The rats injected subcutaneously with CCl4 for 6 weeks resulted in hepatic fibrotic changes increased hydroxyproline and MDA levels, and decreased GSH-px and SOD levels, whereas melatonin reversed these effects. Furthermore, melatonin inhibited the expression of NF-kappaB in liver tissue and decreasing production of proinflammatory cytokines such as TNF-alpha and IL-1beta from KCs in fibrotic rats. These present results suggest that melatonin ameliorates carbon tetrachloride-induced hepatic fibrogenesis in rats via inhibition of oxidative stress and proinflammatory cytokines production.     

HGF regulates the activation of TGF‐β1 in rat hepatocytes and hepatic stellate cells

Hepatocyte growth factor (HGF) ameliorates experimental liver fibrosis through many mechanisms, including degradation of accumulated collagen and decreased expression of fibrotic genes. Investigating an upstream mechanism in which HGF could decrease many fibrotic effectors, we asked whether HGF regulates activation of the fibrotic cytokine transforming growth factor‐beta 1 (TGF‐β1). Specifically, we tested whether HGF decreases the levels of active TGF‐β1, and whether such decrease depends on the predominantly hepatocyte‐secreted protease plasmin, and whether it depends on the TGF‐β1 activator thrombospondin‐1 (TSP‐1). With hepatocyte monocultures, we found HGF‐induced hepatocyte proliferation did increase total levels of plasmin, while decreasing gene expression of fibrotic markers (PAI‐1, TGF‐β1, and TIMP‐2). With in vitro models of fibrotic liver (HSC‐T6 hepatic stellate cells, or co‐cultures of HSC‐T6 and hepatocytes), we found high levels of fibrosis‐associated proteins such as TSP‐1, active TGF‐β1, and Collagen I. HGF treatment on these fibrotic cultures stimulated plasmin levels; increased TSP‐1 protein cleavage; and decreased the levels of active TGF‐β1 and Collagen I. When plasmin was blocked by the inhibitor aprotinin, HGF could no longer decrease TGF‐β1 activation and Collagen I. Meanwhile, the TSP‐1‐specific peptide inhibitor, LSKL, reduced TGF‐β1 to the same level as in the HGF‐treated cultures; combining LSKL and HGF treatments caused no further decrease, suggesting that HGF affects the TSP‐1 dependent pathway of TGF‐β1 activation. Therefore, HGF can decrease TGF‐β1 activation and TGF‐β1‐dependent fibrotic markers, by stimulating hepatocytes to produce plasmin, and by antagonizing TSP‐1‐dependent activation of TGF‐β1. J. Cell. Physiol. 228: 393–401, 2013. © 2012 Wiley Periodicals, Inc.     

Inhibition of Notch Signaling by a γ-Secretase Inhibitor Attenuates Hepatic Fibrosis in Rats

Notch signaling is essential to the regulation of cell differentiation, and aberrant activation of this pathway is implicated in human fibrotic diseases, such as pulmonary, renal, and peritoneal fibrosis. However, the role of Notch signaling in hepatic fibrosis has not been fully investigated. In the present study, we show Notch signaling to be highly activated in a rat model of liver fibrosis induced by carbon tetrachloride (CCl₄), as indicated by increased expression of Jagged1, Notch3, and Hes1. Blocking Notch signaling activation by a γ-secretase inhibitor, DAPT, significantly attenuated liver fibrosis and decreased the expression of snail, vimentin, and TGF-β1 in association with the enhanced expression of E-cadherin. The study in vitro revealed that DAPT treatment could suppress the EMT process of rat hepatic stellate cell line (HSC-T6). Interestingly, DAPT treatment was found not to affect hepatocyte proliferation in vivo. In contrast, DAPT can inhibit hepatocyte apoptosis to some degree. Our study provides the first evidence that Notch signaling is implicated in hepatic fibrogenesis and DAPT treatment has a protective effect on hepatocytes and ameliorates liver fibrosis. These findings suggest that the inhibition of Notch signaling might present a novel therapeutic approach for hepatic fibrosis.     

Silencing p53 inhibits interleukin 10-induced activated hepatic stellate cell senescence and fibrotic degradation in vivo

Activated hepatic stellate cells are reported to play a significant role in liver fibrogenesis. Beside the phenotype reversion and apoptosis of activated hepatic stellate cells, the senescence of activated hepatic stellate cells limits liver fibrosis. Our previous researches have demonstrated that interleukin-10 could promote hepatic stellate cells senescence via p53 signaling pathway in vitro. However, the relationship between expression of p53 and senescence of activated hepatic stellate cells induced by interleukin-10 in fibrotic liver is unclear. The purpose of present study was to explore whether p53 plays a crucial role in the senescence of activated hepatic stellate cells and degradation of collagen mediated by interleukin-10. Hepatic fibrosis animal model was induced by carbon tetrachloride through intraperitoneal injection and transfection of interleukin-10 gene to liver was performed by hydrodynamic-based transfer system. Depletions of p53 in vivo and in vitro were carried out by adenovirus-based short hairpin RNA against p53. Regression of fibrosis was assessed by liver biopsy and collagen staining. Cellular senescence in the liver was observed by senescence-associated beta-galactosidase (SA-β-Gal) staining. Immunohistochemistry, immunofluorescence double staining, and Western blot analysis were used to evaluate the senescent cell and senescence-related protein expression. Our data showed that interleukin-10 gene treatment could lighten hepatic fibrosis induced by carbon tetrachloride and induce the aging of activated hepatic stellate cells accompanied by up-regulating the expression of aging-related proteins. We further demonstrated that depletion of p53 could abrogate up-regulation of interleukin-10 on the expression of senescence-related protein in vivo and vitro. Moreover, p53 knockout in fibrotic mice could block not only the senescence of activated hepatic stellate cells, but also the degradation of fibrosis induced by interleukin-10 gene intervention. Taken together, our results suggested that interleukin-10 gene treatment could attenuate carbon tetrachloride-induced hepatic fibrosis by inducing senescence of activated hepatic stellate cells in vivo, and this induction was closely related to p53 signaling pathway.     

Antagonistic regulation of transmembrane 4 L6 family member 5 attenuates fibrotic phenotypes in CCl(4) -treated mice

The development of liver fibrosis from chronic inflammation can involve epithelial-mesenchymal transition (EMT). Severe liver fibrosis can progress to cirrhosis, and further to hepatocellular carcinoma. Because the tetraspanin transmembrane 4 L6 family member 5 (TM4SF5) induces EMT and is highly expressed in hepatocellular carcinoma, it is of interest to investigate whether TM4SF5 expression is correlated with EMT processes during the development of fibrotic liver features. Using hepatic cells in vitro and a CCl(4) -mediated mouse liver in?vivo model, we examined whether TM4SF5 is expressed during liver fibrosis mediated by CCl(4) administration and whether treatment with anti-TM4SF5 reagent blocks the fibrotic liver features. Here, we found that TM4SF5 expression was induced by the transforming growth factor (TGF)β1 and epidermal growth factor signaling pathways in hepatocytes in vitro. In the CCl(4) -mediated mouse liver model, TM4SF5 was expressed during the liver fibrosis mediated by CCl(4) administration and correlated with α-smooth muscle actin expression, collagen I deposition, and TGFβ1 and epidermal growth factor receptor signaling activation in fibrotic septa regions. Interestingly, treatment with anti-TM4SF5 reagent blocked the TM4SF5-mediated liver fibrotic features: the formation of fibrotic septa with α-smooth muscle actin expression and collagen I deposition was attenuated by treatment with anti-TM4SF5 reagent. These results suggest that TM4SF5 expression mediated by TGFβ1 and growth factor can facilitate fibrotic processes during chronic liver injuries. TM4SF5 is thus a candidate target for prevention of liver fibrosis following chronic liver injury.