Enhanced matrix degradation after withdrawal of TGF-beta1 triggers hepatocytes from apoptosis to proliferation and regeneration

TIMP-1 Promotes Expression of MCP-1 and Macrophage Migration by Inducing Fli-1 in Experimental Liver Fibrosis

Background and Aims

Tissue inhibitor of metalloproteinase-1 (TIMP-1) plays a role in the excessive generation of extracellular matrix in liver fibrosis. This study aimed to explore the pathways through which TIMP-1 controls monocyte chemoattractant protein-1 (MCP-1) expression and promotes hepatic macrophage recruitment.

Methods

Liver fibrosis was triggered through carbon tetrachloride, and an adeno-associated virus containing small interfering RNA targeting TIMP-1 (siRNA-TIMP-1) was administered to both rats and mice. We assessed the extent of fibrosis and macrophage recruitment. The molecular mechanisms regulating macrophage recruitment by TIMP-1 were investigated through transwell migration assays, luciferase reporter assays, the use of pharmacological modulators, and an analysis of extracellular vesicles (EVs).

Results

siRNA-TIMP-1 alleviated carbon tetrachloride-induced liver fibrosis, reducing macrophage migration and MCP-1 expression. Co-culturing macrophages with hepatic stellate cells (HSCs) post-TIMP-1 downregulation inhibited macrophage migration. In siRNA-TIMP-1-treated HSCs, microRNA-145 (miRNA-145) expression increased, while the expression of Friend leukemia virus integration-1 (Fli-1) and MCP-1 was inhibited. Downregulation of Fli-1 led to decreased MCP-1 expression, whereas Fli-1 overexpression increased MCP-1 expression within HSCs. Transfection with miRNA-145 mimics reduced the expression of both Fli-1 and MCP-1, while miRNA-145 inhibitors elevated the expression of both Fli-1 and MCP-1 in HSCs. miRNA-145 bound directly to the 3'-UTR of Fli-1, and miRNA-145-enriched EVs secreted by HSCs after TIMP-1 downregulation influenced macrophage recruitment.

Conclusions

TIMP-1 induces Fli-1 expression through miRNA-145, subsequently increasing MCP-1 expression and macrophage recruitment. MiRNA-145-enriched EVs from HSCs can transmit biological information and magnify the function of TIMP-1.

A standardized pomegranate fruit extract ameliorates thioacetamide-induced liver fibrosis in rats via AGE-RAGE-ROS signaling

This work aimed to investigate a possible mechanism that may mediate the hepatoprotective effects of pomegranate fruit extract (PFE) against thioacetamide (THIO)-induced liver fibrosis in rats. Male Sprague Dawley rats were randomly allocated into four groups (n = 8 each): control; PFE (150 mg/kg/day, orally); THIO (200 mg/kg, i.p, 3 times a week); and THIO and PFE-treated groups. Oral PFE treatment decreased liver/body weight ratio by 12.4%, diminished serum function levels of ALT, AST, ALP, LDH, and total bilirubin, increased serum albumin, boosted hepatic GSH (by 35.6%) and SOD (by 17.5%), and significantly reduced hepatic levels of ROS, MDA, 4-HNE, AGEs, and RAGE in THIO-fibrotic rats relative to untreated THIO group. Moreover, PFE administration downregulated the hepatic levels of profibrotic TGF-β1 (by 23.0%, P < 0.001) and TIMP-1 (by 41.5%, P < 0.001), attenuated α-SMA protein expression, decreased serum HA levels (by 41.3%), and reduced the hepatic levels of the fibrosis markers hydroxyproline (by 26.0%, P < 0.001), collagen type IV (by 44.3%, P < 0.001) and laminin (by 43.4%, P < 0.001) compared to the untreated THIO group. The histopathological examination has corroborated these findings, where PFE decreased hepatic nodule incidence, attenuated portal necroinflammation and reduced extent of fibrosis. These findings may suggest that oral PFE administration could slow the progression of hepatic fibrogenesis via reducing hepatic levels of AGEs, RAGE, ROS, TGF-β1, and TIMP-1.

Protective effects of paclitaxel on thioacetamide-induced liver fibrosis in a rat model

Liver fibrosis is a public health burden that is highly associated with morbidity and mortality. Therefore, this study aims to explore the anti-fibrotic effects of low dose of paclitaxel (PTX) against thioacetamide (TAA)-induced liver fibrosis in rats and the possible mechanisms involved. TAA was administered at a dose of 200 mg/kg twice weekly for 6 weeks in rats to induce liver fibrosis similar to that in humans. Liver dysfunction was shown by increased alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and γ-glutamyl transferase, along with histopathological changes. Liver fibrosis was confirmed by Masson's Trichome staining, increased collagen content, and elevated α-smooth muscle actin (α-SMA) protein expression. In addition, TAA induced liver apoptosis as indicated by the increased terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells in liver tissues. This study demonstrated that the administration of PTX (0.3 mg/kg/i.p.) three times a week for 6 weeks significantly alleviated functional and biochemical changes induced by TAA in addition to improving the liver architecture. PTX attenuated liver fibrosis as reflected by the decreased collagen content and α-SMA protein expression. Additionally, PTX attenuated liver apoptosis as indicated by the decreased TUNEL-positive cells. Moreover, PTX prevented TAA-induced elevation of transforming growth factor-β1 (TGF-β1), platelet-derived growth factor-BB (PDGF-BB), and tissue inhibitor of metalloproteinase 1 (TIMP-1) levels in liver tissues. These findings suggest that the low dose of PTX prevented TAA-induced liver fibrosis in rats, possibly by inhibiting the expression of TGF-β1 and PDGF-BB and subsequently suppressing the apoptosis and the expression of TIMP-1.

Berberine prevents non-alcoholic steatohepatitis-derived hepatocellular carcinoma by inhibiting inflammation and angiogenesis in mice

Hepatocellular carcinoma (HCC) is one of the most malignant and poor prognosis tumors, which was increasingly caused by nonalcoholic fatty liver disease/nonalcoholic steatohepatitis (NAFLD/NASH) in western countries. In this study, we aimed to investigate the mechanism and therapeutic prospect of berberine in the treatment of NASH-HCC mice. Combination of STZ injection and high fat and high-cholesterol diet (HFHC) was used to establish NASH-HCC model. The effect of berberine intervention is studied from histology, biochemistry and molecular level. Our results showed that administration of berberine to NASH-HCC mice reduced the incidence of tumors and mitigated NASH. Berberine significantly reduced the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), glucose (GLU), high-density lipoprotein (HDL), low-density lipoprotein (LDL) and total cholesterol (TC). Transcriptome sequencing and bioinformatics analysis identified numberous genes and various pathways may participate in the favorite effect of berberine. Specifically, berberine suppressed the expressions of genes related to lipogenesis, inflammation, fibrosis and angiogenesis. Moreover, our results showed that berberine suppressed phosphorylation of p38MAPK and ERK as well as COX2 expression significantly. This suggested berberine achieved its biological functions mainly by regulating inflammation and angiogenesis genes involving p38MAPK/ERK-COX2 pathways. This study demonstrated the anti-tumor effects of berberine and its possible mechanism, providing a potential drug for treating NASH-HCC.

Regression of fibrosis by cilostazol in a rat model of thioacetamide-induced liver fibrosis: Up regulation of hepatic cAMP, and modulation of inflammatory, oxidative stress and apoptotic biomarkers

In liver fibrosis, conversion of fibroblasts to profibrogenic myofibroblasts significantly drives the development of the disease. A crucial role of cyclic adenosine monophosphate (cAMP) in regulation of fibroblast function has been reported. Increase in cAMP levels has been found to decrease fibroblast proliferation, inhibit their conversion to myofibroblast, and stimulate their death. cAMP is generated by adenyl cyclase (AC), and degraded by cyclic nucleotide phosphodiesterase (PDE). In this study, the antifibrotic effect of a PDE inhibitor, cilostazol (Cilo), on a rat model of liver fibrosis induced by thioacetamide (TAA) was investigated. Four groups of rats were used; the first group received the vehicles and served as the normal control group, while liver fibrosis was induced in the other groups using (TAA, 200 mg/kg/biweekly for 8 successive weeks, ip). The last two groups were treated with Cilo (50 and 100 mg/kg/day, po, respectively). Induction of liver fibrosis in TAA-treated rats was observed as evidenced by the biochemical and histopathological findings. On the other hand, a potent antifibrotic effect was observed in the groups treated with Cilo, with preference to the higher dose. In these groups, a significant increase in the liver content of cAMP was demonstrated that was accompanied by reduction in the hepatic expression of key fibrogenic cytokines, growth factors, and inflammatory biomarkers, including interleukin-6, tumor necrosis factor-alpha, nuclear factor kappa B, and transforming growth factor-beta as compared to TAA group. Moreover, amelioration of TAA-induced oxidative stress and apoptosis in the liver has been observed. These findings reveal the antifibrotic effect of Cilo against TAA-induced liver fibrosis in rats, and suggest regulation of cAMP pathway, together with the modulation of oxidative stress, inflammation, and apoptosis as mechanistic cassette underlines this effect.

The apparent competitive action of ECM proteases and cross-linking enzymes during fibrosis: Applications to drug discovery

Progressive loss of organ function in most organs is associated with fibrosis, a tissue state associated with abnormal matrix buildup. If highly progressive, the fibrotic process eventually leads to organ failure and death. Fibrosis is a basic connective tissue lesion defined by the increase in the amount of fibrillar extracellular matrix (ECM) components in a tissue or organ. In addition, intrinsic changes in important structural cells can induce the fibrotic response by regulating the differentiation, recruitment, proliferation and activation of extracellular matrix-producing myofibroblasts. ECM enzymes belonging to the family of matrix metalloproteinases (MMPs) and lysyl oxidases (LOXs) play a crucial role in ECM remodeling and regeneration. MMPs have a catalytic role in degradation of ECM, whereas LOX/LOXLs mediate ECM, especially collagen, cross-linking and stiffening. Importantly, enzymes from both families are elevated during the fibrotic response to tissue injury and its resolution. Yet, the apparent molecular competition or antagonistic activities of these enzyme families during the various stages of fibrosis is often overlooked. In this review, we discuss the diverse roles of MMPs and LOX/LOXL2 in chronic organ fibrosis. Finally, we review contemporary therapeutic strategies for fibrosis treatment, based on neutralization of MMP and LOX activity, as well as the development of novel drug delivery approaches.

Emerging insights into the role of matrix metalloproteases as therapeutic targets in fibrosis

Fibrosis is the extensive accumulation and buildup of extracellular matrix components, especially fibrillar collagens, during wound healing in response to tissue injury. During all individual stages of fibrosis ECM proteases, mainly matrix metalloproteinases, have diverse roles. The functional role of MMPs and their endogenous inhibitors are differentiated among their family members, and according to the different stages of fibrosis. MMPs levels are elevated in several inflammatory and non-inflammatory fibrotic tissues contributing to the development, progression or resolution of the disease, whereas in other tissues their expression levels can be diminished or be stable to the baseline. The biological roles of MMPs during fibrosis are not fully resolved, but they seem to differ according the specific member of the family, the affected tissue and the stage of the fibrotic response. Remarkably, some members of the family exhibit profibrotic actions while other function as antifibrotic molecules. Diverse animal models indicate that MMPs are contributing in processes related to immunity, tissue repair and ECM turnover, providing significant impact on mechanisms related to fibrosis. For that purpose, these proteases are considered as pharmacological targets and new biological drugs have been developed in order to treat fibrosis.

Ethanol sensitizes hepatocytes for TGF-β-triggered apoptosis

Alcohol abuse is a global health problem causing a substantial fraction of chronic liver diseases. Abundant TGF-β—a potent pro-fibrogenic cytokine—leads to disease progression. Our aim was to elucidate the crosstalk of TGF-β and alcohol on hepatocytes. Primary murine hepatocytes were challenged with ethanol and TGF-β and cell fate was determined. Fluidigm RNA analyses revealed transcriptional effects that regulate survival and apoptosis. Mechanistic insights were derived from enzyme/pathway inhibition experiments and modulation of oxidative stress levels. To substantiate findings, animal model specimens and human liver tissue cultures were investigated. Results: On its own, ethanol had no effect on hepatocyte apoptosis, whereas TGF-β increased cell death. Combined treatment led to massive hepatocyte apoptosis, which could also be recapitulated in human HCC liver tissue treated ex vivo. Alcohol boosted the TGF-β pro-apoptotic gene signature. The underlying mechanism of pathway crosstalk involves SMAD and non-SMAD/AKT signaling. Blunting CYP2E1 and ADH activities did not prevent this effect, implying that it was not a consequence of alcohol metabolism. In line with this, the ethanol metabolite acetaldehyde did not mimic the effect and glutathione supplementation did not prevent the super-induction of cell death. In contrast, blocking GSK-3β activity, a downstream mediator of AKT signaling, rescued the strong apoptotic response triggered by ethanol and TGF-β. This study provides novel information on the crosstalk between ethanol and TGF-β. We give evidence that ethanol directly leads to a boost of TGF-β’s pro-apoptotic function in hepatocytes, which may have implications for patients with chronic alcoholic liver disease.

Adenoviral‑bone morphogenetic protein‑7 and/or doxazosin therapies promote the reversion of fibrosis/cirrhosis in a cirrhotic hamster model

Liver fibrosis occurs in the presence of continuous insults, including toxic or biological agents. Novel treatments must focus on ceasing the progression of cellular damage, promoting the regeneration of the parenchyma and inhibition of the fibrotic process. The present study analyzed the effect of bone morphogenetic protein (BMP)-7 gene therapy with or without co-treatment with doxazosin in a model of liver cirrhosis in hamsters. The serum alanine aminotransferase, aspartate aminotransferase and albumin levels were analyzed spectrophotometrically. Tissue hepatic samples were analyzed by hematoxylin and eosin for parenchymal structure and Sirius red for collagen fiber content. BMP-7 and α-smooth muscle actin (SMA)-positive cells were detected by immunohistochemistry. BMP-7 and collagen type I content in hepatic tissue were analyzed by western blotting, and tissue inhibitor of metalloproteinases (TIMP)-2 and matrix metalloproteinase (MMP)-13 expression levels were detected by reverse transcription-quantitative polymerase chain reaction. The present study detected a significant reduction of collagen type I deposits in the group treated with adenoviral-transduction with BMP-7 and doxazosin. In animals with BMP-7 and doxazosin therapy, α-SMA-positive cells were 31.7 and 29% significantly decreased compared with animals with placebo, respectively. Adenoviral-BMP-7 transduction and/or doxazosin treatments actively induced decrement in type I collagen deposition via increased MMP-13 and reduced TIMP-2 expression. In conclusion, the adenovirus-BMP-7 gene therapy and the doxazosin therapy are potential candidates for the diminution of fibrosis in the liver, although combination of both therapies does not improve the individual anti-fibrotic effect once cirrhosis is established.

The Role of Butylidenephthalide in Targeting the Microenvironment Which Contributes to Liver Fibrosis Amelioration

The treatment of liver fibrosis has clinical limitations because of its multiple etiologies, such as epithelial–mesenchymal transition (EMT) promotion, cell regeneration and remodeling dysfunction, inflammatory cell activation, and scar tissue deposition. These factors might be considered as a new target for the fibrotic microenvironment, leading to increased fibrogenesis and liver fibrosis. Here, we investigate a small molecule named butylidenephthalide (BP) and its multiple effects on liver fibrosis treatment. Thioacetamide was used in vivo to induce chronic liver fibrosis. BP was administered orally in rats for a period of 2 and 4 weeks, which resulted in a significantly reduced fibrosis score (p < 0.05) and (p < 0.001), respectively. The inflammatory reaction of macrophage infiltration were reduced in the administration of BP, which led to the decrease in the transaminase levels. Moreover, we also found liver functions recovering (due to the increased serum albumin and reduced prothrombin time) where liver cells regenerated, which can be seen in the increase of Ki-67 on Oval cell. In addition, the fibrotic scar was also reduced, along with the expression of matrix metalloprotease by hepatic stellate cell. Furthermore, regarding the mechanism/study of EMT reduced by BP, the knockdown of BMP-7, which could reduce α-SMA expression, was mediated by the regulation of TGF-β, which implies its major role on EMT. Finally, in the in vivo study, BP treatment of liver fibrosis was reduced by Bmp7 knockdown in zebrafish, suggesting that BP leads to the reduction of liver fibrosis, which also depends on BMP-7 induction. These results suggest that BP had multiple targets for treating liver fibrosis in the following ways: reduction of EMT, decreasing inflammatory reaction, and liver cell proliferation. This multiple targets approach provided a new mechanism to treat liver injury and fibrosis.

Integrins and integrin-related proteins in cardiac fibrosis

Cardiac fibrosis is one of the major components of the healing mechanism following any injury of the heart and as such may contribute to both systolic and diastolic dysfunction in a range of pathophysiologic conditions. Canonically, it can occur as part of the remodeling process that occurs following myocardial infarction or that follows as a response to pressure overload. Integrins are cell surface receptors which act in both cellular adhesion and signaling. Most importantly, in the context of the continuously contracting myocardium, they are recognized as mechanotransducers. They have been implicated in the development of fibrosis in several organs, including the heart. This review will focus on the involvement of integrins and integrin-related proteins, in cardiac fibrosis, outlining the roles of these proteins in the fibrotic responses in specific cardiac pathologies, discuss some of the common end effectors (angiotensin II, transforming growth factor beta 1 and mechanical stress) through which integrins function and finally discuss how manipulation of this set of proteins may lead to new treatments which could prove useful to alter the deleterious effects of cardiac fibrosis.

Anti-fibrosis effects of Huisheng oral solution in CCl4-induced hepatic fibrosis in rat

AIM

Some gradient of Huisheng oral solution (HOS) has been reported to have anti-fibrosis activity. This study was designed to investigate whether HOS could inhibit liver fibrosis and to elucidate its molecular mechanism of action.

MATERIALS AND METHODS

Hepatic fibrosis model in rat was induced by subcutaneous injection of CCl4. Rats in the treatment group were administrated with HOS intragastrically. Hematoxylin and eosin (H and E) staining and Masson's trichrome staining were used to examine the changes in liver pathology. Levels of ALT, AST, LDH, hyaluronic acid (HA) and laminin (LN) in serum and hydroxyproline (Hyp) in liver were detected by biochemical examination and radioimmunoassay, respectively. The expression and distribution of Smad3, TGF-β1, α-SMA and TIMP-1 were observed and the active TGF-β1 was tested.

RESULTS

Our data demonstrated that HOS alleviated CCl4-induced collagen deposition in liver tissue, improved liver condition and liver function in rats. HOS also significantly reduced the expression and distribution of Smad3, TGF-β1, α-SMA and TIMP-1 as well as decreased active TGF-β1.

CONCLUSIONS

This study revealed that HOS attenuates the development of liver fibrosis through suppressing the TGF-β1 pathway. It provides us a new approach to treatment of liver fibrosis.

Modulation of thioacetamide-induced liver fibrosis/cirrhosis by sildenafil treatment

Sildenafil citrate is a phosphodiesterase-5 inhibitor, approved for the treatment of erectile dysfunction. It enhances nitric-oxide-induced vasodilatation and it promotes angiogenesis. A relationship between angiogenesis and hepatic fibrosis has long been speculated, where the 2 are believed to progress together. In this study, the ability of sildenafil (10 mg·(kg body mass)(-1), orally, once daily) to prevent and also reverse liver fibrosis/cirrhosis experimentally induced by thioacetamide injection (200 mg·kg(-1), intraperitoneal (i.p.), 3 times·week(-1)) in male Sprague-Dawley rats has been investigated. Sildenafil administration, either to prevent or to reverse liver fibrosis/cirrhosis significantly improved the estimated hepatic functions, reduced hepatic hydroxyproline and, in turn, hepatic collagen content, as well as reducing serum levels of the pro-fibrogenic mediator transforming growth factor β1. In co-ordination with such improvement, fibrosis grades declined and fibrosis retracted. Herein, the observed results provide evidence for the potential therapeutic efficacy of sildenafil as an antifibrotic agent.

Antifibrotic effects of a recombinant adeno-associated virus carrying small interfering RNA targeting TIMP-1 in rat liver fibrosis

Elevated tissue inhibitor of metalloproteinase 1 (TIMP-1) expression contributes to excess production of extracellular matrix in liver fibrosis. Herein, we constructed a recombinant adeno-associated virus (rAAV) carrying siRNA of the TIMP-1 gene (rAAV/siRNA-TIMP-1) and investigated its effects on liver fibrosis in rats. Two models of rat liver fibrosis, the carbon tetrachloride and bile duct ligation models, were treated with rAAV/siRNA-TIMP-1. In the carbon tetrachloride model, rAAV/siRNA-TIMP-1 administration attenuated fibrosis severity, as determined by histologic analysis of hepatic collagen accumulation, hydroxyproline content, and concentrations of types I and III collagen in livers and sera. Levels of mRNA and active matrix metalloproteinase (MMP) 13 were elevated, whereas levels of mRNA and active MMP-2 were decreased. Moreover, a marked decrease was noted in the expression of α-smooth muscle actin, a biomarker of activated hepatic stellate cells (HSCs), and transforming growth factor-β1, critical for the development of liver fibrosis. Similarly, rAAV/siRNA-TIMP-1 treatment significantly alleviated bile duct ligation-induced liver fibrosis. Furthermore, this treatment dramatically suppressed TIMP-1 expression in HSCs from both model rats. These data indicate that the administration of rAAV/siRNA-TIMP-1 attenuated liver fibrosis by directly elevating the function of MMP-13 and diminishing activated HSCs. It also resulted in indirect decreased expression of type I collagen, MMP-2, and transforming growth factor-β1. In conclusion, rAAV/siRNA-TIMP-1 may be an effective antifibrotic gene therapy agent.

NDRG2 ameliorates hepatic fibrosis by inhibiting the TGF-β1/Smad pathway and altering the MMP2/TIMP2 ratio in rats

Liver fibrosis is a worldwide clinical issue. It has been well established that activated hepatic stellate cells (HSCs) are responsible for excessive extracellular matrix (ECM) deposition in chronically damaged livers. The identification of key elements that control HSCs activation will help to further our understanding of liver fibrosis and improve the outcome of clinical treatment. This study demonstrates that N-Myc downstream-regulated gene 2 (NDRG2) is a potential regulator of liver fibrosis as NDRG2 mRNA and protein levels were reduced during HSCs activation. In addition, enhanced NDRG2 expression reduced Smad3 transcription and phosphorylation, which inhibited HSCs activation by blocking the TGF-β1 signal. Moreover, NDRG2 contributed to an increase in the ratio of matrix metalloproteinase 2 (MMP2) to tissue inhibitor of matrix metalloproteinase 2 (TIMP2), which may facilitate the degradation of the ECM. In dimethylnitrosamine (DMN)-induced fibrotic rat livers, adenovirus-mediated NDRG2 overexpression resulted in decreased ECM deposition and improved liver function compared with controls. In conclusion, the present findings indicate that the modulation of NDRG2 is a promising strategy for the treatment of liver fibrosis.

NDRG2 ameliorates hepatic fibrosis by inhibiting the TGF-β1/Smad pathway and altering the MMP2/TIMP2 ratio in rats

Liver fibrosis is a worldwide clinical issue. It has been well established that activated hepatic stellate cells (HSCs) are responsible for excessive extracellular matrix (ECM) deposition in chronically damaged livers. The identification of key elements that control HSCs activation will help to further our understanding of liver fibrosis and improve the outcome of clinical treatment. This study demonstrates that N-Myc downstream-regulated gene 2 (NDRG2) is a potential regulator of liver fibrosis as NDRG2 mRNA and protein levels were reduced during HSCs activation. In addition, enhanced NDRG2 expression reduced Smad3 transcription and phosphorylation, which inhibited HSCs activation by blocking the TGF-β1 signal. Moreover, NDRG2 contributed to an increase in the ratio of matrix metalloproteinase 2 (MMP2) to tissue inhibitor of matrix metalloproteinase 2 (TIMP2), which may facilitate the degradation of the ECM. In dimethylnitrosamine (DMN)-induced fibrotic rat livers, adenovirus-mediated NDRG2 overexpression resulted in decreased ECM deposition and improved liver function compared with controls. In conclusion, the present findings indicate that the modulation of NDRG2 is a promising strategy for the treatment of liver fibrosis.

Transcription factors ETF, E2F, and SP-1 are involved in cytokine-independent proliferation of murine hepatocytes

The cellular basis of liver regeneration has been intensely investigated for many years. However, the mechanisms initiating hepatocyte "plasticity" and priming for proliferation are not yet fully clear. We investigated alterations in gene expression patterns during the first 72 hours of C57BL/6N mouse hepatocyte culture on collagen monolayers (CM), which display a high basal frequency of proliferation in the absence of cytokines. Although many metabolic genes were down-regulated, genes related to mitogen-activated protein kinase (MAPK) signaling and cell cycle were up-regulated. The latter genes showed an overrepresentation of transcription factor binding sites (TFBS) for ETF (TEA domain family member 2), E2F1 (E2F transcription factor 1), and SP-1 (Sp1 transcription factor) (P < 0.001), all depending on MAPK signaling. Time-dependent increase of ERK1/2 phosphorylation occurred during the first 48 hours (and beyond) in the absence of cytokines, accompanied by an enhanced bromodeoxyuridine labeling index of 20%. The MEK inhibitor PD98059 blunted these effects indicating MAPK signaling as major trigger for this cytokine-independent proliferative response. In line with these in vitro findings, liver tissue of mice challenged with CCl(4) displayed hepatocytes with intense p-ERK1/2 staining and nuclear SP-1 and E2F1 expression. Furthermore, differentially expressed genes in mice after partial hepatectomy contained overrepresented TFBS for ETF, E2F1, and SP-1 and displayed increased expression of E2F1.

CONCLUSION

Cultivation of murine hepatocytes on CM primes cells for proliferation through cytokine-independent activation of MAPK signaling. The transcription factors ETF, E2F1, and SP-1 seem to play a pronounced role in mediating proliferation-dependent differential gene expression. Similar events, but on a shorter time-scale, occur very early after liver damage in vivo.

Effects of bicyclol on immunological liver fibrosis in rats

Liver fibrosis results from chronic liver injury in conjunction with the accumulation of extracellular matrix proteins. The present study was performed to estimate the effect of bicyclol on bovine serum albumin (BSA)-induced immunological liver fibrosis in rats. Bicyclol (1) (100, 200, and 300 mg/kg) was given to rats by oral administration once a day for 5 weeks from the fourth week of intravenous injection of BSA. Blood and liver tissues were collected for the measurement of hydroxyproline (Hyp), procollagen type III (PIIIP), hyaluronic acid (HA), and transforming growth factor beta-1 (TGF-beta1) levels and liver pathological changes. The mRNA and protein expressions of hepatic TGF-beta1, interleukin-1 (IL-1), IL-10, MMP-2, TIMP-1, phosphorylated p38 (Pp38), and Smad2/3 were detected by reverse transcription polymerase chain reaction and Western blot. As a result, bicyclol significantly protected against BSA-induced liver fibrosis as evidenced by the reduction of elevated serum HA, PIIIP, and hepatic Hyp in rats, while liver pathological changes were also alleviated. The overexpressions of hepatic TGF-beta1, IL-1beta, IL-10, MMP-2, and TIMP-1 were suppressed by bicyclol in BSA-treated rats. The phosphorylations of Pp38 and Smad2/3 were also inhibited after bicyclol treatment. The hepatoprotection of bicyclol was mainly due to the modulation on the expression of inflammatory/anti-inflammatory cytokines, downregulation of hepatic TGF-beta1, and inhibition of hepatic collagen synthesis.

Neohepatocytes from alcoholics and controls express hepatocyte markers and display reduced fibrogenic TGF-ß/Smad3 signaling: advantage for cell transplantation?

BACKGROUND

Liver transplantation is the only definitive treatment for end stage liver disease. Donor organ scarcity raises a growing interest in new therapeutic options. Recently, we have shown that injection of monocyte-derived NeoHepatocytes can increase survival in rats with extended liver resection. In order to apply this technology in humans with chronic liver diseases in an autologous setting, we generated NeoHepatocytes from patients with alcoholic liver disease and healthy controls and compared those to human hepatocytes.

METHODS

We generated NeoHepatocytes from alcoholics with Child A and B cirrhosis and healthy controls. Hepatocytes marker expression and transforming growth factor (TGF)-beta signaling was investigated by RT-PCR, Western blot, immunofluorescent staining, and adenoviral reporter assays. Glucose and urea was measured photometrically. Phase I and II enzyme activities were measured using fluorogenic substrates. Neutral lipids were visualized by Oil Red O staining.

RESULTS

There was no significant difference in generation and yield of NeoHepatocytes from alcoholics and controls. Hepatocyte markers, e.g., cytokeratin18 and alcohol dehydrogenase 1, increased significantly throughout differentiation. Glucose and urea production did not differ between alcoholics and controls and was comparable to human hepatocytes. During differentiation, phase I and II enzyme activities increased, however remained significantly lower than in human hepatocytes. Fat accumulation was induced by treatment with insulin, TGF-beta and ethanol only in differentiated cells and hepatocytes. TGF-beta signaling, via Smad transcription factors, critically required for progression of chronic liver disease, was comparable among the investigated cell types, merely expression of Smad1 and -3 was reduced (approximately 30 and approximately 60%) in monocytes, programmable cells of monocytic origin, and NeoHepatocytes. Subsequently, expression of TGF-beta regulated pro-fibrogenic genes, e.g., connective tissue growth factor and fibronectin was reduced.

CONCLUSIONS

Generation of NeoHepatocytes from alcoholics, displaying several features of human hepatocytes, offers new perspectives for cell therapeutic approaches, as cells can be obtained repeatedly in a noninvasive manner. Furthermore, the autologous setting reduces the need for immunosuppressants, which may support recovery of patients which are declined for liver transplantation.

Inhibition of extracellular signal-regulated kinase 1 by adenovirus mediated small interfering RNA attenuates hepatic fibrosis in rats

Extracellular signal-regulated kinase 1 (ERK1) is a critical part of the mitogen-activated protein kinase signal transduction pathway, which is involved in hepatic fibrosis. However, the effect of down-regulation of ERK1 on hepatic fibrosis has not been reported. Here, we induced hepatic fibrosis in rats with dimethylnitrosamine administration or bile duct ligation. An adenovirus carrying small interfering RNA targeting ERK1 (AdshERK1) was constructed to determine its effect on hepatic fibrosis, as evaluated by histological and immunohistochemical examination. Our results demonstrated that AdshERK1 significantly reduced the expression of ERK1 and suppressed proliferation and levels of fibrosis-related genes in hepatic stellate cells in vitro. More importantly, selective inhibition of ERK1 remarkably attenuated the deposition of the extracellular matrix in fibrotic liver in both fibrosis models. In addition, both hepatocytes and biliary epithelial cells were proven to exert the ability to generate the myofibroblasts depending on the insults of the liver, which were remarkably reduced by AdshERK1. Furthermore, up-regulation of ERK1 paralleled the increased expression of transforming growth factor beta1 (TGF-beta1), vimentin, snail, platelet-derived growth factor-BB (PDGF-BB), bone morphogenetic protein 4 (BMP4), and small mothers against decapentaplegic-1 (p-Smad1), and was in reverse correlation with E-cadherin in the fibrotic liver. Nevertheless, inhibition of ERK1 resulted in the increased level of E-cadherin in parallel with suppression of TGF-beta1, vimentin, snail, PDGF-BB, BMP4, and p-Smad1. Interestingly, AdshERK1 treatment promoted hepatocellular proliferation.

CONCLUSION

Our study provides the first evidence for AdshERK1 suppression of hepatic fibrosis through the reversal of epithelial-mesenchymal transition of both hepatocytes and biliary epithelial cells without interference of hepatocellular proliferation. This suggests that ERK1 is implicated in hepatic fibrogenesis and selective inhibition of ERK1 by small interfering RNA may present a novel option for hepatic fibrosis treatment.

Effects of ursolic acid on the expression of transforming growth factor-β1 and alpha-smooth muscle actin in fibrotic liver in rats

AIM: To observe the effects of ursolic acid (UA) on the expression of transforming growth factor-β1 (TGF-β1) mRNA and protein and alpha-smooth muscle actin (α-SMA) protein in liver tissue of rats with dimethylnitrosamine (DMN)-induced liver fibrosis, and explore the mechanism underlying their anti-fibrotic effects.

METHODS: After liver fibrosis in rats was induced by DMN for four weeks, rats were given different doses of UA, colchicine and placebo for another four weeks by intraperitoneal injection. Hepatic lobule constitution, hepatic cell necrosis and fibrous tissue hyperplasia were observed by HE and VG staining. The levels of TGF-β1 and α-SMA proteins were measured by immunohistochemistry and Western blot. The expression of TGF-β1 mRNA was measured by RT-PCR.

RESULTS: The degree of hepatic cell necrosis and fibrous tissue hyperplasia was decreased markedly in rats treated with UA. The expression levels of TGF-β1 mRNA and protein and α-SMA protein in the model control group were significantly higher than those in the normal control group (8.76 ± 1.47 vs 1.48 ± 0.24, 0.60 ± 0.11 vs 0.05 ± 0.02 and 0.51 ± 0.10 vs 0.09 ± 0.02, respectively; all P < 0.01). The expression levels of TGF-β1 protein in the U1 (low-dose UA) group and colchine group were lower than those in the model control group, while the expression levels of TGF-β1 protein in the U2 (medium-dose UA) and U3 (high-dose UA) groups were not only significantly lower than that in the model control group (5.32 ± 1.63 and 3.98 ± 0.67 vs 8.76 ± 1.47, both P < 0.01), but also lower than that in the colchine group (7.14 ± 1.29, P < 0.05 or 0.01). Furthermore, the expression levels of TGF-β1 mRNA in the U2 and U3 groups were lower than those in the model control group (0.36 ± 0.07 and 0.25 ± 0.06 vs 0.60 ± 0.11, both P < 0.01) and colchine group (0.47 ± 0.10, P < 0.05 or 0.01). The expression levels of α-SMA protein in the U1, U2 and U3 groups were significantly lower than those in the model control group (0.36 ± 0.08, 0.23 ± 0.02 and 0.15 ± 0.03 vs 0.51±0.10, all P < 0.01) and colchine group (0.43 ± 0.05, all P < 0.01).

CONCLUSION: UA significantly ameliorates DMN-induced liver fibrosis perhaps through activation of HSC and downregulation of TGF-β1 expression.

Adenovirus-mediated transfer of siRNA against PAI-1 mRNA ameliorates hepatic fibrosis in rats

BACKGROUND/AIMS

Plasminogen activator inhibitor-1 (PAI-1) is a potential profibrotic molecule. The aim of this study was to evaluate the therapeutic effect of PAI-1 small interfering RNA (siRNA) on experimental hepatic fibrosis and investigate the intrinsic mechanisms.

METHODS

Hepatic fibrosis in rats was induced by dimethylnitrosamine (DMN) administration or bile duct ligation (BDL). An adenovirus carrying PAI-1 shRNA (AdshPAI) was generated and administered via tail vein injection. The expression of PAI-1 was confirmed by real-time RT-PCR and immunohistochemistry. The effect of AdshPAI on fibrosis was evaluated by histological and immunohistochemical examination.

RESULTS

We found that PAI-1 was downregulated after AdshPAI administration. Liver fibrosis was significantly improved after AdshPAI administration in both DMN and BDL models. AdshPAI treatment facilitated matrix degradation by correcting the levels of matrix metalloproteinases (MMPs) and its inhibitors (TIMPs) through upregulation of MMP9, MMP13 and downregulation of TIMP-1. Moreover, AdshPAI treatment stimulated hepatocellular proliferation and inhibited cellular apoptosis.

CONCLUSIONS

This study suggests that AdshPAI treatment has a protective effect on hepatocytes and ameliorates liver fibrogenesis. Inhibiting the upregulation of PAI-1 during liver fibrosis may be an antifibrotic pathway worth exploiting.

Expression of transforming growth factor β1 and its type I receptor in gastric cancer

AIM: To evaluate the significance of transforming growth factor-β1 (TGF-β1) and its β I type receptor (TGF-β R1) in the pathogenesis of gastric carcinoma.

METHODS: TGF-β1 and TGF-β R1 were detected by immunohistochemistry in and real-time PCR (RT-PCR) 50 cases of gastric carcinoma, 19 cases of atrophic gastritis and 18 cases of normal gastric mucosa.

RESULTS: Immunohistochemistry demonstrated that the positive expression rates of TGF-β1 and TGF-β R1 were significantly higher in gastric carcinoma (80.0% and 75.0%) than in normal gastric mucosa (33.3% and 27.8%) and atrophic gastritis (36.8% and 36.8%) (P < 0.01). The lower the differentiation of gastric carcinoma was, the higher the expression of TGF-β1 and TGF-β R1 was (r = 35.58, P < 0.01). Furthermore, the expression of TGF-β1 and TGF-β R1 mRNA was significantly higher in gastric carcinoma than in normal gastric mucosa and atrophic gastritis (TGF-β1: 4.20 ± 0.51 vs 9.15 ± 2.12, 8.22 ± 1.81; TGF-β R1: 1.28 ± 0.48 vs 5.55 ± 1.48, 4.19 ± 0.95).

CONCLUSION: High expression of TGF-β1 and TGF-β R1 is correlated with the development, biologic behavior and prognosis of gastric carcinoma.

Oval cell proliferation in p16INK4a expressing mouse liver is triggered by chronic growth stimuli

Terminal differentiation requires molecules also involved in aging such as the cell cycle inhibitor p16^INK4a.Like other organs, the adult liver represents a quiescent organ with terminal differentiated cells, hepatocytes and cholangiocytes. These cells retain the ability to proliferate in response to liver injury or reduction of liver mass. However, under conditions which prevent mitotic activation of hepatocytes, regeneration can occur instead from facultative hepatic stem cells.For therapeutic application a non-toxic activation of this stem cell compartment is required. We have established transgenic mice with conditional overexpression of the cell cycle inhibitor p16^INK4a in hepatocytes and have provoked and examined oval cell activation in adult liver in response to a range of proliferative stimuli.We could show that the liver specific expression of p16^INK4a leads to a faster differentiation of hepatocytes and an activation of oval cells already in postnatal mice without negative consequences on liver function.

Expression of MMPs and TIMPs in liver fibrosis - a systematic review with special emphasis on anti-fibrotic strategies

In liver tissue matrix metalloproteinases (MMPs) and their specific inhibitors (tissue inhibitors of metalloproteinases, TIMPs) play a pivotal role in both, fibrogenesis and fibrolysis. The current knowledge of the pathophysiology of liver fibrogenesis with special emphasis on MMPs and TIMPs is presented. A systematic literature search was conducted. All experimental models of liver fibrosis that evaluated a defined anti-fibrotic intervention in vivo or in vitro considering MMPs and TIMPs were selected. The methodological quality of all these publications has been critically appraised using an objective scoring system and the content has been summarized in a table.

A novel formulation of oxygen‐carrying matrix enhances liver‐specific function of cultured hepatocytes

Oxygen is an important component of the cellular microenvironment, mediating cell survival, differentiation, and function. Oxygen supply is a limiting factor during culture of highly metabolic cells such as hepatocytes. Here we present a simple formulation of a fluorocarbon-based oxygen carrier embedded in collagen gel that increases oxygen concentration in culture 6-fold. Rat hepatocytes cultured on oxygen carrier-collagen showed a significant increase in viability and function. Cytochrome P450IA1 activity was increased by 140% in serum-free cultures and by 820% in serum-containing cultures. The significantly higher hepatocellular function on oxygen carrier-collagen matrix persisted and increased during long-term culture. Long-term albumin secretion was increased by 350% in serum-free cultures and by 166% in serum-containing culture. Long-term urea secretion was increased by 79% in serum-free cultures and by 76% in serum-containing cultures. We conclude that oxygen supply may limit hepatocyte function in vitro. This limitation can be overcome by addition of an oxygen carrier to the extracellular matrix. Culture of hepatocytes on oxygen-carrying matrix mimics the oxygen-rich environment of the liver and provides a simple method for enhanced long-term function.

Filtrate of fermented mycelia from Antrodia camphorata reduces liver fibrosis induced by carbon tetrachloride in rats

AIM: To investigate the effects of filtrate of fermented mycelia from Antrodia camphorata (FMAC) on liver fibrosis induced by carbon tetrachloride (CCl₄) in rats.

METHODS: Forty Wistar rats were divided randomly into control group and model group. All model rats were given 200 mL/L CCl₄ (2 mL/Kg, po) twice a week for 8 wk. Four weeks after CCl₄ treatment, thirty model rats were further divided randomly into 3 subgroups: CCl₄ and two FMAC subgroups. Rats in CCl₄ and 2 FMAC subgroups were treated with FMAC 0, 0.5 and 1.0 g/kg, daily via gastrogavage beginning at the fifth week and the end of the eighth week. Spleen weight, blood synthetic markers (albumin and prothrombin time) and hepatic malondialdehyde (MDA) and hydroxyproline (HP) concentrations were determined. Expression of collagen I, tissue inhibitor of metalloproteinases (TIMP)-1 and transforming growth factor β1 (TGF-β1) mRNA were detected by RT-PCR. Histochemical staining of Masson’s trichrome was performed.

RESULTS: CCl₄ caused liver fibrosis, featuring increased prothrombin time, hepatic MDA and HP contents, and spleen weight and decreased plasma albumin level. Compared with CCl₄ subgroup, FMAC subgroup (1 g/kg) significantly decreased the prothrombin time (36.7 ± 7.2 and 25.1 ± 10.2 in CCl₄ and FMAC groups, respectively, P < 0.05) and increased plasma albumin concentration (22.7 ± 1.0 and 30.7 ± 2.5 in CCl₄ and FMAC groups, respectively, P  < 0.05). Spleen weight was significantly lower in rats treated with CCl₄ and FMAC (1 g/kg) compared to CCl₄ treated rats only (2.7 ± 0.1 and 2.4 ± 0.2 in CCl₄ and FMAC groups, respectively, P  < 0.05). The amounts of hepatic MDA and HP in CCl₄ ± FAMC (1 g/kg) subgroup were also lower than those in CCl₄ subgroup (MDA: 3.9 ± 0.1 and 2.4 ± 0.6 in CCl₄ and CCl₄ + FMAC groups, respectively, P < 0.01; HP: 1730.7 ± 258.0 and 1311.5 ± 238.8 in CCl₄ and CCl₄ + FMAC groups, respectively, P <0.01). Histologic examinations showed that CCl₄ + FMAC subgroups had thinner or less fibrotic septa than CCl₄ group. RT-PCR analysis indicated that FMAC (1 g/kg) reduced mRNA levels of collagen I, TIMP-1 and TGF-β1 (collagen I: 5.63 ± 2.08 and 1.78 ± 0.48 in CCl₄ and CCl₄ + FMAC groups, respectively, P < 0.01; TIMP-1: 1.70 ± 0.82 and 0.34 ± 0.02 in CCl₄ and CCl₄ + FMAC groups, respectively, P < 0.01; TGF-β1:38.03 ± 11.9 and 4.26 ± 2.17 in CCl₄ and CCl₄ + FMAC groups, respectively, P < 0.01) in the CCl₄-treated liver.

CONCLUSION: It demonstrates that FMAC can retard the progression of liver fibrosis induced by CCl₄ in rats.