Seminars in medicine of the Beth Israel Hospital, Boston. The cellular basis of hepatic fibrosis. Mechanisms and treatment strategies

Activated hepatic stellate cells are dependent on self-collagen, cleaved by membrane type 1 matrix metalloproteinase for their growth

Stellate cells are distributed throughout organs, where, upon chronic damage, they become activated and proliferate to secrete collagen, which results in organ fibrosis. An intriguing property of hepatic stellate cells (HSCs) is that they undergo apoptosis when collagen is resolved by stopping tissue damage or by treatment, even though the mechanisms are unknown. Here we disclose the fact that HSCs, normal diploid cells, acquired dependence on collagen for their growth during the transition from quiescent to active states. The intramolecular RGD motifs of collagen were exposed by cleavage with their own membrane type 1 matrix metalloproteinase (MT1-MMP). The following evidence supports this conclusion. When rat activated HSCs (aHSCs) were transduced with siRNA against the collagen-specific chaperone gp46 to inhibit collagen secretion, the cells underwent autophagy followed by apoptosis. Concomitantly, the growth of aHSCs was suppressed, whereas that of quiescent HSCs was not. These in vitro results are compatible with the in vivo observation that apoptosis of aHSCs was induced in cirrhotic livers of rats treated with siRNAgp46. siRNA against MT1-MMP and addition of tissue inhibitor of metalloproteinase 2 (TIMP-2), which mainly inhibits MT1-MMP, also significantly suppressed the growth of aHSCs in vitro. The RGD inhibitors echistatin and GRGDS peptide and siRNA against the RGD receptor αVβ1 resulted in the inhibition of aHSCs growth. Transduction of siRNAs against gp46, αVβ1, and MT1-MMP to aHSCs inhibited the survival signal of PI3K/AKT/IκB. These results could provide novel antifibrosis strategies.

Alcohol Disrupts Human Liver Stem/Progenitor Cell Proliferation and Differentiation

OBJECTIVE

Excessive alcohol consumption injures the liver resulting in various liver diseases including liver cirrhosis. Advanced liver disease continues to be a major challenge to human health. Liver stem/progenitor cells (LSPCs) are tissue specific precursors with a distinct capacity of multi-lineage differentiation. These precursor cells may play an important role in the process of tissue injury repair and pathological transition of liver structures. At the present time, knowledge about the effect of alcohol on LSPC function during the development of alcoholic liver disease remains absent. This study was conducted to investigate changes in LSPC activity of proliferation and differentiation following alcohol exposure. The disruption of cell signaling mechanisms underlying alcohol-induced alteration of LSPC activities was also examined.

METHODS

Primary and immortalized human liver stem cells (HL1-1 cells and HL1-hT1 cells, respectively) were cultured in media optimized for cell proliferation and hepatocyte differentiation in the absence and presence of ethanol. Changes in cell morphology, proliferation and differentiation were determined. Functional disruption of cell signaling components following alcohol exposure was examined.

RESULTS

Ethanol exposure suppressed HL1-1 cell growth [as measured by cell 5-bromo-2-deoxyuridine (BrdU) incorporation] mediated by epidermal growth factor (EGF) or EGF plus interleukin-6 (IL-6) in an ethanol dose-dependent manner. Similarly, ethanol inhibited BrdU incorporation into HL1-hT1 cells. Cyclin D1 mRNA expression by HL1-hT1 cells was suppressed when cells were cultured with 50 and 100 mM ethanol. Ethanol exposure induced morphological change of HL1-1 cells toward a myofibroblast-like phenotype. Furthermore, ethanol down-regulated E-cadherin expression while increasing collagen I expression by HL1-1 cells. Ethanol also stimulated Snail transcriptional repressor (Snail) and α-smooth muscle actin (α-SMA) gene expression by HL1-1 cells.

CONCLUSION

These results demonstrate that the direct effect of alcohol on LSPCs is inhibiting their proliferation and promoting mesenchymal transition during their differentiation. Alcohol interrupts LSPC differentiation through interfering Snail signaling.

Mechanisms of fibrogenesis in liver cirrhosis: The molecular aspects of epithelial-mesenchymal transition

Liver injuries are repaired by fibrosis and regeneration. The cause of fibrosis and diminished regeneration, especially in liver cirrhosis, is still unknown. Epithelial-mesenchymal transition (EMT) has been found to be associated with liver fibrosis. The possibility that EMT could contribute to hepatic fibrogenesis reinforced the concept that activated hepatic stellate cells are not the only key players in the hepatic fibrogenic process and that other cell types, either hepatic or bone marrow-derived cells could contribute to this process. Following an initial enthusiasm for the discovery of this novel pathway in fibrogenesis, more recent research has started to cast serious doubts upon the real relevance of this phenomenon in human fibrogenetic disorders. The debate on the authenticity of EMT or on its contribution to the fibrogenic process has become very animated. The overall result is a general confusion on the meaning and on the definition of several key aspects. The aim of this article is to describe how EMT participates to hepatic fibrosis and discuss the evidence of supporting this possibility in order to reach reasonable and useful conclusions.

Signal transduction of platelet-induced liver regeneration and decrease of liver fibrosis

Platelets contain three types of granules: alpha granules, dense granules, and lysosomal granules. Each granule contains various growth factors, cytokines, and other physiological substances. Platelets trigger many kinds of biological responses, such as hemostasis, wound healing, and tissue regeneration. This review presents experimental evidence of platelets in accelerating liver regeneration and improving liver fibrosis. The regenerative effect of liver by platelets consists of three mechanisms; i.e., the direct effect on hepatocytes, the cooperative effect with liver sinusoidal endothelial cells, and the collaborative effect with Kupffer cells. Many signal transduction pathways are involved in hepatocyte proliferation. One is activation of Akt and extracellular signal-regulated kinase (ERK)1/2, which are derived from direct stimulation from growth factors in platelets. The other is signal transducer and activator of transcription-3 (STAT3) activation by interleukin (IL)-6 derived from liver sinusoidal endothelial cells and Kupffer cells, which are stimulated by contact with platelets during liver regeneration. Platelets also improve liver fibrosis in rodent models by inactivating hepatic stellate cells to decrease collagen production. The level of intracellular cyclic adenosine monophosphate (cyclic AMP) is increased by adenosine through its receptors on hepatic stellate cells, resulting in inactivation of these cells. Adenosine is produced by the degradation of adenine nucleotides such as adenosine diphosphate (ADP) and adenosine tri-phosphate (ATP), which are stored in abundance within the dense granules of platelets.

Sophocarpine attenuates liver fibrosis by inhibiting the TLR4 signaling pathway in rats

AIM: To explore the effect of sophocarpine on experimental liver fibrosis and the potential mechanism involved.

METHODS: Sophocarpine was injected intraperitoneally in two distinct rat hepatic fibrosis models induced either by dimethylnitrosamine or bile duct ligation. Masson’s trichrome staining, Sirius red staining and hepatic hydroxyproline level were used for collagen determination. Primary hepatic stellate cells (HSCs) were isolated and treated with different concentrations of sophocarpine. Real-time reverse transcription-polymerase chain reaction was used to detect the mRNA levels of fibrotic markers and cytokines. The expression of pathway proteins was measured by Western blot. The Cell Counting Kit-8 test was used to detect the proliferation rate of activated HSCs treated with a gradient concentration of sophocarpine.

RESULTS: Sophocarpine decreased serum levels of aminotransferases and total bilirubin in rats under chronic insult. Moreover, administration of sophocarpine suppressed extracellular matrix deposition and prevented the development of hepatic fibrosis. Furthermore, sophocarpine inhibited the expression of α-smooth muscle actin (SMA), interleukin (IL)-6, transforming growth factor-β1 (TGF-β1), Toll-like receptor 4 (TLR4), and extracellular-related kinase (ERK) in rats. Sophocarpine also down-regulated the mRNA expression of α-SMA, collagen I, collagen III, TGF-β1, IL-6, tumor necrosis factor-α and monocyte chemoattractant protein-1, and decreased protein levels of TLR4, p-ERK, p-JNK, p-P38 and p-IKK in vitro after Lipopolysaccharide induction. In addition, sophocarpine inhibited the proliferation of HSCs accompanied by a decrease in the expression of Cyclin D1. The protein level of proliferating cell nuclear antigen was decreased in activated HSCs following a gradient concentration of sophocarpine.

CONCLUSION: Sophocarpine can alleviate liver fibrosis mainly by inhibiting the TLR4 pathway. Sophocarpine may be a potential chemotherapeutic agent for chronic liver diseases.

Role of platelets in chronic liver disease and acute liver injury

Platelets contain not only hemostatic factors but also many growth factors that play important roles in wound healing and tissue repair. Platelets have already been used for the promotion of tissue regeneration in the clinical setting, such as dental implantation and plastic surgery. Thrombocytopenia, which is frequently found in patients with chronic liver disease and cirrhosis, is due to various causes such as decreased thrombopoietin production and accelerated platelet destruction caused by hypersplenism. However, the relationship between thrombocytopenia and hepatic pathogenesis and the role of platelets in chronic liver disease are poorly understood. In acute liver injury, it is reported that platelets are recruited to the liver and contribute to liver damage by promoting the induction of chemotactic factors and the accumulation of leukocytes in the liver, whereas platelets or mediators released by platelets can have a protective effect against liver injury. In this review, we highlight the recent accumulated knowledge concerning the role of platelets in chronic liver disease and acute liver injury.

Hepatic Fibrosis Inhibitory Effect of Peptides Isolated from Navicula incerta on TGF-β1 Induced Activation of LX-2 Human Hepatic Stellate Cells

In this study, novel peptides (NIPP-1, NIPP-2) derived from Navicula incerta (microalgae) protein hydrolysate were explored for their inhibitory effects on collagen release in hepatic fibrosis with the investigation of its underlying mechanism of action. TGF-β1 activated fibrosis in LX-2 cells was examined in the presence or absence of purified peptides NIPP-1 and NIPP-2. Besides the mechanisms of liver cell injury, protective effects of NIPP-1 and NIPP-2 were studied to show the protective mechanism against TGF-β1 stimulated fibrogenesis. Our results showed that the core protein of NIPP-1 peptide prevented fibril formation of type I collagen, elevated the MMP level and inhibited TIMP production in a dose-dependent manner. The treatment of NIPP-1 and NIPP-2 on TGF-β1 induced LX-2 cells alleviated hepatic fibrosis. Moreover, α-SMA, TIMPs, collagen and PDGF in the NIPP-1 treated groups were significantly decreased. Therefore, it could be suggested that NIPP-1 has potential to be used in anti-fibrosis treatment.

Texture-based classification of liver fibrosis using MRI

PURPOSE

To investigate the ability of texture analysis of MRI images to stage liver fibrosis. Current noninvasive approaches for detecting liver fibrosis have limitations and cannot yet routinely replace biopsy for diagnosing significant fibrosis.

MATERIALS AND METHODS

Forty-nine patients with a range of liver diseases and biopsy-confirmed fibrosis were enrolled in the study. For texture analysis all patients were scanned with a T2 -weighted, high-resolution, spin echo sequence and Haralick texture features applied. The area under the receiver operating characteristics curve (AUROC) was used to assess the diagnostic performance of the texture analysis.

RESULTS

The best mean AUROC achieved for separating mild from severe fibrosis was 0.81. The inclusion of age, liver fat and liver R2 variables into the generalized linear model improved AUROC values for all comparisons, with the F0 versus F1-4 comparison the highest (0.91).

CONCLUSION

Our results suggest that a combination of MRI measures, that include selected texture features from T2 -weighted images, may be a useful tool for excluding fibrosis in patients with liver disease. However, texture analysis of MRI performs only modestly when applied to the classification of patients in the mild and intermediate fibrosis stages.

IFN-γ deficiency attenuates hepatic inflammation and fibrosis in a steatohepatitis model induced by a methionine- and choline-deficient high-fat diet

Cytokines play important roles in all stages of steatohepatitis, including hepatocyte injury, the inflammatory response, and the altered function of sinusoidal cells. This study examined the involvement of a major inflammatory cytokine, interferon-γ (IFN-γ), in the progression of steatohepatitis. In a steatohepatitis model by feeding a methionine- and choline-deficient high-fat (MCDHF) diet to both wild-type and IFN-γ-deficient mice, the liver histology, expression of genes encoding inflammatory cytokines, and fibrosis-related markers were examined. To analyze the effects of IFN-γ on Kupffer cells in vitro, we examined the tumor necrosis factor-α (TNF-α) production by a mouse macrophage cell line. Forty two days of MCDHF diet resulted in weight loss, elevated aminotransferases, liver steatosis, and inflammation in wild-type mice. However, the IFN-γ-deficient mice exhibited less extensive changes. RT-PCR revealed that the expression of tumor necrosis factor-α (TNF-α), transforming growth factor-β, inducible nitric oxide synthase, interleukin-4 and osteopontin were increased in wild-type mice, although they were suppressed in IFN-γ-deficient mice. Seventy days of MCDHF diet induced much more liver fibrosis in wild-type mice than in IFN-γ-deficient mice. The expression levels of fibrosis-related genes, α-smooth muscle actin, type I collagen, tissue inhibitor of matrix metalloproteinase-1, and matrix metalloproteinase-2, were dramatically increased in wild-type mice, whereas they were significantly suppressed in IFN-γ-deficient mice. Moreover, in vitro experiments showed that, when RAW 264.7 macrophages were treated with IFN-γ, they produced TNF-α in a dose-dependent manner. The present study showed that IFN-γ deficiency might inhibit the inflammatory response of macrophages cells and subsequently suppress stellate cell activation and liver fibrosis. These findings highlight the critical role of IFN-γ in the progression of steatohepatitis.

Guggulsterone attenuates activation and survival of hepatic stellate cell by inhibiting nuclear factor kappa B activation and inducing apoptosis

BACKGROUND AND AIM

Liver fibrosis is associated with the deposition of the extracellular matrix, and hepatic stellate cells (HSCs) are the major source of these matrix proteins. Guggulsterone has recently been shown to induce apoptosis in several cell lines. Thus, the aim of this study was to evaluate whether guggulsterone has antifibrotic activities by reducing the activation and survival of HSCs.

METHODS

Apoptotic and fibrosis-related signaling pathways and nuclear factor kappa B (NF-κB) activity were explored in LX-2 cells, an immortalized human HSC line, and in a mice model of liver fibrosis.

RESULTS

Guggulsterone suppressed LX-2 cell growth in a dose- and activation-dependent manner. This growth suppression was due to the induction of HSC apoptosis, which was mediated by the activation of c-Jun N-terminal kinase and mitochondrial apoptotic signaling. Additionally, guggulsterone regulated phosphorylation of Akt and adenosine monophosphate-activated protein kinase, which were subsequently proven responsible for the guggulsterone-induced HSC growth suppression. Guggulsterone inhibited NF-κB activation in LX-2 cells, which is one of the major mediators in HSC activation. Indeed, guggulsterone decreased collagen α1 synthesis and α-smooth muscle actin expression in these cells. Compared with the control mice or mice treated with a low dose of guggulsterone, high dose of guggulsterone significantly decreased the extent of collagen deposition and the percentage of activated HSCs undergoing apoptosis.

CONCLUSIONS

These results demonstrate that guggulsterone suppressed HSC activation and survival by inhibiting NF-κB activation and inducing apoptosis. Therefore, guggulsterone may be useful as an antifibrotic agent in chronic liver diseases.

Saikosaponin A of Bupleurum chinense (Chaihu) elevates bone morphogenetic protein 4 (BMP-4) during hepatic stellate cell activation

BACKGROUND

Saikosaponin a (SSa) is a compound extracted from a Chinese herb which has been widely used in treating liver diseases such as liver fibrosis. However, the mechanism of SSa in treatment of liver fibrosis still remain unclear. Our previous study demonstrated that BMP4 stimulated the expression of smooth muscle alpha actin (α-SMA) in the liver. Therefore, the current study investigates the effect of SSa on BMP4 expression during hepatic stellate cell activation in a human hepatic stellate cell line.

METHODS

LX-2 cells were cultured in DMEM/F12 with fetal bovine serum and treated with SSa in different times and concentrations. The expression of BMP4 was examined by both RT-PCR and western blot analysis. WST-1 proliferation reagent was used to evaluate cell proliferation. α-SMA and Bax protein expression was determined by western blot analysis.

RESULTS

Both mRNA and protein levels of BMP-4 were significantly inhibited in LX-2 cells after 5 μM SSa treatment. SSa significantly inhibited LX-2 proliferation at the concentration of 5μM while BMP-4 had no effect on LX-2 proliferation. BMP-4 increased α-SMA expression in LX-2 while SSa reduced α-SMA expression. In addition SSa could neutralize the effect of BMP-4 on α-SMA expression. SSd also inhibited BMP4 expression but not NG. Bax protein expression was induced in these cells by 5 μM SSa.

CONCLUSION

SSa could down-regulate BMP-4 expression and inhibit hepatic stellate cell activation. Therefore, SSa could be used for treatment of liver disease with elevated BMP-4 expression.

The autoregulatory feedback loop of microRNA-21/programmed cell death protein 4/activation protein-1 (MiR-21/PDCD4/AP-1) as a driving force for hepatic fibrosis development

Sustained activation of hepatic stellate cells (HSCs) leads to hepatic fibrosis, which is characterized by excessive collagen production, and for which there is no available drug clinically. Despite tremendous progress, the cellular activities underlying HSC activation, especially the driving force in the perpetuation stage, are only partially understood. Recently, microRNA-21 (miR-21) has been found to be prevalently up-regulated during fibrogenesis in different tissues, although its detailed role needs to be further elucidated. In the present study, miR-21 expression was examined in human cirrhotic liver samples and in murine fibrotic livers induced by thioacetamide or carbon tetrachloride. A dramatic miR-21 increase was noted in activated HSCs. We further found that miR-21 maintained itself at constant high levels by using a microRNA-21/programmed cell death protein 4/activation protein-1 (miR-21/PDCD4/AP-1) feedback loop. Disrupting this loop with miR-21 antagomir or AP-1 inhibitors significantly suppressed fibrogenic activities in HSCs and ameliorated liver fibrosis. In contrast, reinforcing this loop with small interfering RNA (siRNA) against PDCD4 promoted fibrogenesis in HSCs. Further analysis indicated that the up-regulated miR-21 promoted the central transforming growth factor-β (TGF-β) signaling pathway underlying HSC activation. In summary, we suggest that the miR-21/PDCD4/AP-1 autoregulatory loop is one of the main driving forces for hepatic fibrosis progression. Targeting this aberrantly activated feedback loop may provide a new therapeutic strategy and facilitate drug discovery against hepatic fibrosis.

The Medicinal Values of Culinary-Medicinal Royal Sun Mushroom (Agaricus blazei Murrill)

Agaricus blazei Murrill (ABM), a mushroom native to Brazil, is a basidiomycete brown fungus, which is popularly known as "Cogumelo do Sol" in Brazil or "Himematsutake" in Japan, and there has been a prominent increase in the use of ABM for therapeutic and medicinal purposes. ABM is useful against a variety of diseases like cancer, tumor, chronic hepatitis, diabetes, atherosclerosis, hypercholesterolemia, and so on. In this review, we demonstrated various pharmacological effects of ABM, so that we can use different effects of ABM against different diseases and provide reference for the study of ABM in the future.

Lipopolysaccharides accelerate hepatic steatosis in the development of nonalcoholic fatty liver disease in Zucker rats

Nonalcoholic fatty liver disease (NAFLD) can develop into end-stage disease that includes cryptogenic cirrhosis and hepatocellular carcinoma. Bacterial endotoxin, for example lipopolysaccharide (LPS), plays an important role in the pathogenesis of NAFLD. The aim of this study was to assess the role of LPS in the development of NAFLD. Twenty-one male Zucker (fa/fa) rats were divided into three groups: rats fed for twelve weeks on a diet rich in disaccharide (D12 group), rats similarly managed but treated with LPS (LPS group), and those on the same diet for 24 weeks (D24 group). Histological examination demonstrated that this protocol induced hepatic steatosis in the LPS and D24 groups. Significant, marked accumulation of lipid droplets was observed in the LPS group, compared with the D24 group. Rats from the LPS group showed a decrease in plasma adiponectin levels, an increase in plasma leptin levels, and greater expression of FAS and SREBP-1c mRNA in the liver, compared with rats from the D24 group. These finding coincided with histological findings. We therefore suggest that LPS may accelerate the progression of hepatic steatosis.

Therapeutic effects of hepatocyte growth factor-overexpressing human umbilical cord blood-derived mesenchymal stem cells on liver fibrosis in rats

Fibrosis is a common end stage for a variety of liver diseases, including most chronic liver diseases, and results from an imbalance between collagen deposition and degradation. Mesenchymal stem cells (MSCs) have the ability to migrate into fibrotic livers and differentiate into hepatocytes. Hepatocyte growth factor (HGF) has potent anti-apoptotic and mitogenic effects on hepatocytes during liver injury and plays an essential role in the development and regeneration of the liver. In this study, human HGF-overexpressing human umbilical cord blood-derived MSCs (hHGF-HUCB-MSCs) were prepared using the pMEX Expression System, and the upregulation of hHGF expression was confirmed by RT-PCR and ELISA. HGF expressed by hHGF-HUCB-MSCs exerted a stimulatory effect on hepatocyte proliferation in vitro. hHGF-HUCB-MSCs were transplanted to investigate the therapeutic effects of these cells on carbon tetrachloride (CCL4)-induced liver fibrosis in a rat model. After 4 weeks of cell treatment once per week with 2 × 10(6) cells, biochemical analysis of the serum and histopathological analysis of the liver tissue were performed. The results of the biochemical analysis of the serum show that the hHGF-HUCB-MSC-treated group had higher levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase, indicating the improvement of liver function. Histopathology showed that the hHGF-HUCB-MSC-treated group had reduction in the density of collagen fibres. Thus hHGF-HUCB-MSCs can enhance liver regeneration and could be useful for the treatment of patients with liver fibrosis or cirrhosis.

Role of thrombospondin-1 in repair of penetrating corneal wounds

PURPOSE

Thrombospondin-1 (THBS1) has been suggested as a corneal wound-healing modulator. Therefore, we compromised the integrity of the cornea to elucidate the role of THBS1.

METHODS

Full-thickness penetrating corneal incisions (1.5 mm) were created in wild type (WT, 129S2/SvPas) and THBS1-deficient mice (Thbs1⁻/⁻), 129S2/SvPas-Thbs1(tm1Hyn)/Thbs1(tm1Hyn)), and allowed to heal up to 1 month, while being monitored by slit-lamp and intravital corneal examinations. Corneas also were examined by transmission electron microscopy and indirect immunofluorescence. To determine how THBS1 was involved in the healing process, we examined THBS1 and α-smooth muscle actin (SMA), a marker of myofibroblasts and myoepithelial cells.

RESULTS

In WT mice by 1 month, corneas appeared transparent with a thin scar, and endothelium and Descemet's membrane (DM) were restored. In contrast, Thbs1⁻/⁻ corneas exhibited chronic edema and persistent opacity after wounding. The DM and endothelium were not restored, and wound contraction was impaired. The THBS1 was localized in epithelial cells at early stages of the healing process, and in the stroma and endothelial cells during later stages. The SMA-positive epithelial cells and myofibroblasts were observed within the healing area at day 4, peaked at day 14, and disappeared at day 30. The SMA-positive cells were reduced greatly in Thbs1⁻/⁻ mice.

CONCLUSIONS

In the current study, we demonstrated that corneal restoration is strikingly compromised by a penetrating incision in Thbs1⁻/⁻ mice. The wound results in persistent edema and wound gaping. This appears to be the result of the lack of endothelial migration and DM restoration. In addition, myofibroblast formation is compromised, resulting in the lack of wound contraction.

Transplantation of bone marrow-derived mesenchymal stem cells after regional hepatic irradiation ameliorates thioacetamide-induced liver fibrosis in rats

BACKGROUND

Recent studies have demonstrated that bone marrow-derived mesenchymal stem cells (BM-MSCs) can potentially revert liver fibrosis, but it is not known if preparative hepatic irradiation (HIR) contributes to the therapeutic effect of transplanted BM-MSCs. In this study, we investigate the effects of HIR on transplanted BM-MSCs in cirrhotic rats and the underlying mechanism by which mesenchymal stem cells (MSCs) relieve liver fibrosis.

MATERIALS AND METHODS

The BM-MSCs from male rats were labeled with CM-Dil and injected via portal vein into two groups of thioacetamide-induced cirrhotic rats, and the controls were injected with the same volume of saline. The right hemiliver of one cirrhotic rat group was irradiated (15 Gy) 4 d before transplantation. Liver function tests and histologic experiments were performed, and the liver population of BM-MSCs was estimated.

RESULTS

The transplantation of MSCs alleviated liver fibrosis and reduced expression of transforming growth factor-β1, Smad2, collagen type I, and α-SMA. HIR preconditioning promoted homing and repopulation of MSCs and resulted in better treatment outcomes.

CONCLUSIONS

HIR preconditioning enhances the effect of BM-MSCs in improving thioacetamide-induced liver fibrosis in rats by promoting their homing and repopulation. BM-MSCs may function by inhibiting transforming growth factor-β1-Smad signaling pathway in the liver.

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.

Interaction of silicon-based quantum dots with gibel carp liver: oxidative and structural modifications

Quantum dots (QDs) interaction with living organisms is of central interest due to their various biological and medical applications. One of the most important mechanisms proposed for various silicon nanoparticle-mediated toxicity is oxidative stress. We investigated the basic processes of cellular damage by oxidative stress and tissue injury following QD accumulation in the gibel carp liver after intraperitoneal injection of a single dose of 2 mg/kg body weight Si/SiO2 QDs after 1, 3, and 7 days from their administration.QDs gradual accumulation was highlighted by fluorescence microscopy, and subsequent histological changes in the hepatic tissue were noted. After 1 and 3 days, QD-treated fish showed an increased number of macrophage clusters and fibrosis, while hepatocyte basophilia and isolated hepatolytic microlesions were observed only after substantial QDs accumulation in the liver parenchyma, at 7 days after IP injection.Induction of oxidative stress in fish liver was revealed by the formation of malondialdehyde and advanced oxidation protein products, as well as a decrease in protein thiol groups and reduced glutathione levels. The liver enzymatic antioxidant defense was modulated to maintain the redox status in response to the changes initiated by Si/SiO2 QDs. So, catalase and glutathione peroxidase activities were upregulated starting from the first day after injection, while the activity of superoxide dismutase increased only after 7 days. The oxidative damage that still occurred may impair the activity of more sensitive enzymes. A significant inhibition in glucose-6-phosphate dehydrogenase and glutathione-S-transferase activity was noted, while glutathione reductase remained unaltered.Taking into account that the reduced glutathione level had a deep decline and the level of lipid peroxidation products remained highly increased in the time interval we studied, it appears that the liver antioxidant defense of Carassius gibelio does not counteract the oxidative stress induced 7 days after silicon-based QDs exposure in an efficient manner.

Molecular MRI of liver fibrosis by a peptide-targeted contrast agent in an experimental mouse model

OBJECTIVES

Cyclic decapeptide CGLIIQKNEC (CLT1) has been demonstrated to target fibronectin-fibrin complexes in the extracellular matrix of different tumors and tissue lesions. Although liver fibrosis is characterized by an increased amount of extracellular matrix consisting of fibril-forming collagens and matrix glycoconjugates such as fibronectin, we aimed to investigate the feasibility of detecting and characterizing liver fibrosis using CLT1 peptide-targeted nanoglobular contrast agent (Gd-P) with dynamic contrast-enhanced magnetic resonance imaging in an experimental mouse model of liver fibrosis at 7 T.

MATERIALS AND METHODS

Gd-P, control peptide KAREC conjugated nanoglobular contrast agent (Gd-CP), and control nontargeting nanoglobular contrast agent (Gd-C) were synthesized. Male adult C57BL/6N mice (22-25 g; N = 54) were prepared and were divided into fibrosis (n = 36) and normal (n = 18) groups. Liver fibrosis was induced in the fibrosis group through subcutaneous injection of 1:3 mixture of carbon tetrachloride (CCl(4)) in olive oil at a dose of 4 μL/g of body weight twice a week for 8 weeks. Dynamic contrast-enhanced MRI was performed in all animals. Dynamic contrast-enhanced magnetic resonance imaging was analyzed to yield postinjection ΔR(1)(t) maps for quantitative measurements. Histological analysis was also performed.

RESULTS

Differential enhancements were observed and characterized between the normal and fibrotic livers using Gd-P at 0.03 mmol/kg, when compared with nontargeted controls (Gd-CP and Gd-C). For Gd-P injection, both the peak and steady-state ΔR(1) of the normal livers were significantly lower than those after 4 and 8 weeks of CCl(4) dosing. Liver fibrogenesis with increased amount of fibronectin in the extracellular space in insulted livers were confirmed by histological observations.

CONCLUSIONS

These results indicated that dynamic contrast-enhanced magnetic resonance imaging with CLT1 peptide-targeted nanoglobular contrast agent can detect and stage liver fibrosis by probing the accumulation of fibronectin in fibrotic livers.

Activation of PPARγ is required for hydroxysafflor yellow A of Carthamus tinctorius to attenuate hepatic fibrosis induced by oxidative stress

Oxidative stress caused hepatic fibrosis by activating hepatic stellate cells (HSCs), which were implemented by depressing PPARγ activation. Hydroxysafflor yellow A (HSYA) as a nature active ingredient with antioxidant capacity was able to effectively attenuate oxidative stress mediated injury. So it will be very interesting to study effect of HSYA on HSCs activation and liver fibrosis, and reveal the role of PPARγ·CCl4 and H2O2 were used to mimic oxidative stress mediated hepatic injury in vitro and in vivo respectively. The anti-fibrosis effects of HSYA were evaluated and its mechanisms were disclosed by applying western blot, histopathological analysis, flow cytometry, RT-PCR and ELISA. Our results showed that HSCs activation and proliferation could be induced by oxidative stress, and the expressive levels of TGF-β1 and TIMP-1, the serum levels of ALT, AST, HA, LN, III-C and IV-C were also enhanced by oxidative stress, which is correlated with liver fibrosis (p<0.05 or p<0.01). HSYA was able to effectively inhibit oxidative stress mediated hepatic injury by increasing the activities of antioxidant enzymes, up regulating the expression of PPARγ and MMP-2, and down regulating the expression of TGF-β1 and TIMP-1, and reducing α-SMA level. The protective effect of HSYA can be significantly attenuated by GW9662 via blocking PPARγ (p<0.05 or p<0.01). Taken together, these results demonstrate that HSYA is able to significantly protect the liver from oxidative stress, which requires for HSYA to stimulate PPARγ activity, reduce cell proliferation and suppress ECM synthesis.

A vitamin D receptor/SMAD genomic circuit gates hepatic fibrotic response

Liver fibrosis is a reversible wound-healing response involving TGFβ1/SMAD activation of hepatic stellate cells (HSCs). It results from excessive deposition of extracellular matrix components and can lead to impairment of liver function. Here, we show that vitamin D receptor (VDR) ligands inhibit HSC activation by TGFβ1 and abrogate liver fibrosis, whereas Vdr knockout mice spontaneously develop hepatic fibrosis. Mechanistically, we show that TGFβ1 signaling causes a redistribution of genome-wide VDR-binding sites (VDR cistrome) in HSCs and facilitates VDR binding at SMAD3 profibrotic target genes via TGFβ1-dependent chromatin remodeling. In the presence of VDR ligands, VDR binding to the coregulated genes reduces SMAD3 occupancy at these sites, inhibiting fibrosis. These results reveal an intersecting VDR/SMAD genomic circuit that regulates hepatic fibrogenesis and define a role for VDR as an endocrine checkpoint to modulate the wound-healing response in liver. Furthermore, the findings suggest VDR ligands as a potential therapy for liver fibrosis.

Transcriptomic and proteomic analysis of human hepatic stellate cells treated with natural taurine

The aim of this study was to investigate the differential expression of genes and proteins between natural taurine (NTau)‑treated hepatic stellate cells (HSCs) and control cells as well as the underlying mechanism of NTau in inhibiting hepatic fibrosis. A microculture tetrazolium (MTT) assay was used to analyze the proliferation of NTau‑treated HSCs. Flow cytometry was performed to compare the apoptosis rate between NTau-treated and non‑treated HSCs. Proteomic analysis using a combination of 2-dimensional gel electrophoresis (2DE) and mass spectrometry (MS) was conducted to identify the differentially expressed proteins. Microarray analysis was performed to investigate the differential expression of genes and real-time polymerase chain reaction (PCR) was used to validate the results. The experimental findings obtained demonstrated that NTau decreased HSC proliferation, resulting in an increased number of cells in the G0/G1 phase and a reduced number of cells in the S phase. Flow cytometric analysis showed that NTau-treated HSCs had a significantly increased rate of apoptosis when compared with the non‑treated control group. A total of 15 differentially expressed proteins and 658 differentially expressed genes were identified by 2DE and MS, and microarray analysis, respectively. Gene ontology (GO) functional analysis indicated that these genes and proteins were enriched in the function clusters and pathways related to cell proliferation, cellular apoptosis and oxidation. The transcriptome and proteome analyses of NTau-treated HSCs demonstrated that NTau is able to significantly inhibit cell proliferation and promote cell apoptosis, highlighting its potential therapeutic benefits in the treatment of hepatic fibrosis.

Prolonged high fat/alcohol exposure increases TRPV4 and its functional responses in pancreatic stellate cells

The present study investigated transient receptor potential vanilloid type 4 (TRPV4) ion channels in pancreatic stellate cells (PSCs) isolated from rats with high-fat and alcohol diet (HFA)-induced chronic pancreatitis. TRPV4 is a calcium-permeable nonselective ion channel responsive to osmotic changes, alcohol metabolites arachidonic acid, anandamide, their derivatives, and injury-related lipid mediators. Male Lewis rats were fed HFA for 6-8 wk before isolation and primary culture of PSCs. Control PSCs were harvested from rats fed standard chow. Immunoreactivity for cytoskeletal protein activation product α-smooth muscle actin (α-SMA) and platelet-derived growth factor receptor-β subunit (PDGFR-β) characterized the cells as PSCs. TRPV4 expression increased in PSCs of HFA-fed rats and control cultures after alcohol treatment (50 mM). Cell responses to activation of inducible TRPV4 were assessed with live cell calcium imaging. Threefold increased and sustained intracellular calcium mobilization responses occurred in 70% of pancreatic stellate cells from HFA-fed rats in response to TRPV4 activators arachidonic acid, lipid second messenger, phorbol ester 4 α-phorbol 12,13-didecanoate (4αPDD), and 50% hypoosmotic media compared with relatively unresponsive PSCs from control rats. Activation responses were attenuated by nonselective TRPV channel blocker ruthenium red. Tumor necrosis factor-α (TNF-α, 1 ng/ml, 16 h) increased responses to 4αPDD in control PSCs. These findings implicate TRPV4-mediated calcium responses inducible after HFA exposure and inflammation in reactive responses of activated PSCs that impair pancreatic function, such as responsiveness to cytokines and the deposition of collagen fibrosis that precipitates ductal blockage and pain.

RNA interference against discoidin domain receptor 2 ameliorates alcoholic liver disease in rats

Discoidin domain receptor 2 (DDR2) is involved in fibrotic disease. However, the exact pathogenic implications of the receptor in early alcoholic liver disease are still controversial. We constructed plasmid vectors encoding short-hairpin RNA against DDR2 to investigate its role in alcoholic liver disease in an immortalized rat hepatic stellate cell line, HSC-T6, and in rats by MTT, RT-PCR and western blot analyses; immunohistochemistry and electron microscopy. Alcohol-induced upregulation of DDR2 was associated with the expression of matrix metalloproteinase 2, the transforming growth factor β1 signaling pathway and tissue inhibitor of metalloproteinase 1; collagen deposition; and extracellular matrix remodeling. Inhibition of DDR2 decreased HSC-T6 cell proliferation and liver injury in rats with 10-week-induced alcoholic liver disease. DDR2 may have an important role in the pathogenesis of early-stage alcoholic liver disease. Silencing DDR2 may be effective in preventing early-stage alcoholic liver disease.

Graptopetalum paraguayense ameliorates chemical-induced rat hepatic fibrosis in vivo and inactivates stellate cells and Kupffer cells in vitro

Background

Graptopetalum paraguayense (GP) is a folk herbal medicine with hepatoprotective effects that is used in Taiwan. The aim of this study was to evaluate the hepatoprotective and antifibrotic effects of GP on experimental hepatic fibrosis in both dimethylnitrosamine (DMN)- and carbon tetrachloride (CCl₄)-induced liver injury rats.

Methods

Hepatic fibrosis-induced rats were fed with the methanolic extract of GP (MGP) by oral administration every day. Immunohistochemistry, biochemical assays, and Western blot analysis were performed. The effects of MGP on the expression of fibrotic markers and cytokines in the primary cultured hepatic stellate cells (HSCs) and Kupffer cells, respectively, were evaluated.

Results

Oral administration of MGP significantly alleviated DMN- or CCl₄-induced liver inflammation and fibrosis. High levels of alanine transaminase, aspartate transaminase, bilirubin, prothrombin activity and mortality rates also decreased in rats treated with MGP. There were significantly decreased hydroxyproline levels in therapeutic rats compared with those of the liver-damaged rats. Collagen I and alpha smooth muscle actin (α-SMA) expression were all reduced by incubation with MGP in primary cultured rat HSCs. Furthermore, MGP induced apoptotic cell death in activated HSCs. MGP also suppressed lipopolysaccharide-stimulated rat Kupffer cell activation by decreasing nitric oxide, tumor necrosis factor-α and interleukin-6 production, and increasing interleukin-10 expression.

Conclusions

The results show that the administration of MGP attenuated toxin-induced hepatic damage and fibrosis in vivo and inhibited HSC and Kupffer cell activation in vitro, suggesting that MGP might be a promising complementary or alternative therapeutic agent for liver inflammation and fibrosis.

The effects of hyperbaric oxygen application against cholestatic oxidative stress and hepatic damage after bile duct ligation in rats

BACKGROUND

The aim of this study was to evaluate the preventive and therapeutic potential of hyperbaric oxygen therapy (HBO) on the liver tissue against bile duct ligation (BDL)-induced oxidative damage and fibrosis in rats.

MATERIALS AND METHODS

We divided 32 adult male Sprague Dawley rats into four groups: sham, sham plus HBO, BDL, and BDL plus HBO; each group contained eight animals. We placed the sham plus HBO and BDL plus HBO groups in an experimental hyperbaric chamber in which we administered pure oxygen at 2.5 atmospheres absolute 100% oxygen for 90 min on 14 consecutive days.

RESULTS

The application of BDL clearly increased the tissue malondialdehyde level, myeloperoxidase activity, and hydroxyproline content and decreased the antioxidant enzymes (superoxide dismutase and catalase activities) and glutathione level. Hyperbaric oxygen therapy treatment significantly decreased the elevated tissue malondialdehyde level, myeloperoxidase activity, and hydroxyproline content and increased the reduced superoxide dismutase and catalase activities and glutathione level in the tissues. The changes demonstrating the bile duct proliferation and fibrosis in expanded portal tracts include the extension of proliferated bile ducts into lobules, mononuclear cells, and neutrophil infiltration into the widened portal areas were observed in BDL group. Treatment of BDL with HBO attenuated alterations in liver histology. Alpha smooth muscle actin, cytokeratin-positive ductular proliferation, and the activity of terminal deoxynucleotidyl transferase 2'-deoxyuridine, 5'-triphosphate nick end labeling in the BDL decreased with HBO treatment.

CONCLUSIONS

The data indicate that HBO attenuates BDL-induced oxidative injury, hepatocytes damage, bile duct proliferation, and fibrosis. The hepatoprotective effect of HBO is associated with antioxidative potential.

The role of complement component 3 (C3) in differentiation of myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) play an important role in the regulation of the immune response. MDSC expansion occurs in many circumstances, including cancer, inflammation, stresses, and transplant tolerance. Liver transplants in mice are spontaneously accepted, but hepatocyte transplants are acutely rejected, suggesting the immunoregulatory activities of liver nonparenchymal cells. We have reported that hepatic stellate cells (HpSCs), the stromal cells in the liver, are immensely immunosuppressive and can effectively protect islet transplants via induction of MDSCs. The present study shows that the addition of HpSCs into dendritic cell (DC) culture promoted development of MDSCs, instead of DCs, which was highly dependent on complement component 3 (C3) from HpSCs. The C3(-/-) HpSCs lost their ability to induce MDSCs and, consequently, failed to protect the cotransplanted islet allografts. HpSCs produced complement activation factor B and factor D which then enhanced C3 cleavage to activation products iC3b and C3d. Addition of exogenous iC3b, but not C3d, into the DC culture led to the differentiation of MDSCs with potent immune-inhibitory function. These findings provide novel mechanistic insights into the differentiation of myeloid cells mediated by local tissue cells, and may assist in the development of MDSC-based therapy in clinical settings.

The anti-fibrotic effect of bone morphogenic protein-7(BMP-7) on liver fibrosis

Background/Aims : Transforming growth factor-β1 (TGF-β1) plays an important role in the pathogenesis of liver fibrosis and cirrhosis. Recombinant human bone morphogenic protein-7 (rhBMP-7) alleviates renal fibrosis and improves kidney function. However, the beneficial effect of BMP-7 on hepatic fibrosis and cirrhosis remains unknown. The purpose of this study was to investigate the prophylactic and therapeutic effects of rhBMP-7 on liver fibrosis and the underlying mechanisms. Methods : Liver fibrosis in the rat model was induced by peritoneal injection of porcine-serum (0.5ml/kg body weight) twice a week over 8 weeks. The effect of rhBMP-7 on hepatic fibrosis was monitored in rhBMP-7 pre-treated and non-treated rats. Pathologic changes were determined by immunohistolocial staining. TGF-β1 expression was investigated by immunohistolocial staining, western blotting, and real-time PCR. Collagen secretion was measured by enzyme-linked immunosorbent assay. Results : Liver fibrosis was significantly reduced by rhBMP-7. The secretion of collagen type-I and -III was decreased by rhBMP-7 in hepatic stellate cells (HSCs) but not in hepatocytes. The anti-fibrotic effect of rhBMP-7 on liver fibrosis was resulted by blocking the nuclear accumulation of Smad2/3 or by inhibiting TGF-β1 expression in HSCs or hepatocytes. Conclusions : The anti-fibrogenic mechanism of rhBMP-7 in the rat liver fibrosis was depended on the reduction of TGF-β1 overexpression and the inhibition of TGF-β1 triggered intracellular signalling in hepatic cells.

The effect of very low-calorie diets on renal and hepatic outcomes: a systematic review

Very low-calorie diets (VLCDs) are an effective means by which to induce clinically significant weight loss. However, their acceptance by health care practitioners and the public is generally lower than that for other nonsurgical weight loss methods. Whilst there is currently little evidence to suggest they have any detrimental effect on hepatic and renal health, data assessing these factors remain limited. We carried out a systematic review of the literature on randomized controlled trials that had a VLCD component and that reported outcomes for hepatic and renal health, published between January 1980 and December 2012. Cochrane criteria were followed, and eight out of 196 potential articles met the inclusion criteria. A total of 548 participants were recruited across the eight studies. All eight studies reported significant weight loss following the VLCD. Changes in hepatic and renal outcomes were variable but generally led to either no change or improvements in either of these. Due to the heterogeneity in the quality and methodology of the studies included, the effect of VLCDs on hepatic and renal outcomes remains unclear at this stage. Further standardized research is therefore required to fully assess the impact of VLCDs on these outcome measures, to better guide clinical practice.

Murine Models of Nonalcoholic Fatty Liver Disease and Steatohepatitis

In 1980, Ludwig et al. first reported patients of steatohepatitis who lacked a history of excessive alcohol consumption but showed liver histology resembling alcoholic hepatitis and progression to cirrhosis of the liver accompanied by inflammation and fibrosis. The development of nonalcoholic steatohepatitis (NASH) is associated with obesity, diabetes mellitus, insulin resistance, and hyperlipidemia. However, the pathogenesis of NASH remains incomplete. A “multiple-hit” hypothesis for the pathogenesis of NASH based on an animal model has been proposed and remains a foundation for research in this field. We review the important dietary and genetic animal models and discuss the pathogenesis of NASH.

α-SMA overexpression associated with increased liver fibrosis in infants with biliary atresia

OBJECTIVE

The mechanisms responsible for increased collagen production and hepatic fibrosis in biliary atresia (BA) remain largely unknown. We evaluated α-smooth muscle actin (α-SMA) expression in liver and the porta hepatis in infants with BA.

METHODS

Immunohistochemical staining for α-SMA and CD68 in the BA liver and porta hepatis was performed. A semiquantitative 3-grade staging system was employed to estimate liver fibrosis. The densities of CD68 in BA liver and the levels of direct bilirubin were assessed in relation to α-SMA expression.

RESULTS

α-SMA was found to be overexpressed in epithelial cells and in periductular collagen fibers. The expression in infants with BA was higher than that in the control group (P < 0.05). The amount of α-SMA in BA was positively correlated with liver fibrosis scores (r = 0.549, P = 0.022). The levels of α-SMA in the liver of BA were negatively related with improvements in direct bilirubin levels, 3 months postoperatively (r = -0.653, P = 0.029). The correlation between the α-SMA and CD-68 expression was not significantly different (r = 0.444, P = 0.057).

CONCLUSIONS

The expression of α-SMA in BA liver is higher than that in contro1 group. α-SMA expression is negatively correlated with the reduction of direct bilirubin, 3 months postoperatively, probably due to fibrosis or cirrhosis affecting the entire biliary system.

Extracellular matrix degradation in liver fibrosis: Biochemistry and regulation

Fibrosis is a highly conserved wound healing response and represents the final common pathway of virtually all chronic inflammatory injuries. Over the past 3 decades detailed analysis of hepatic extracellular matrix synthesis and degradation using approaches incorporating human disease, experimental animal models and cell culture have highlighted the extraordinarily dynamic nature of tissue repair and remodelling in this solid organ. Furthermore emerging studies of fibrosis in other organs demonstrate that basic common mechanisms exist, suggesting that bidirectionality of the fibrotic process may not solely be the preserve of the liver. In this review we will examine the cellular and molecular mechanisms that govern extracellular matrix degradation and fibrosis resolution, and highlight how manipulation of these processes may result in the development of effective anti-fibrotic therapies. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Ameliorative effect of silibinin against N-nitrosodimethylamine-induced hepatic fibrosis in rats

The protective effect of silibinin (SBN) against hepatic fibrosis induced by repeated intermittent administration of N-nitrosodimethylamine (DMN) was investigated in rats. Oral administration of SBN recovered body and liver weight loss and reversed the elevation of serum AST, ALT and ALP accompanied by their fall in the liver tissue in DMN-induced fibrotic rats. Severe oxidative stress induced in fibrotic rats was evidenced by two to three fold elevation in MDA and protein carbonyl levels associated with a fall in the activities of SOD and CAT in repeated DMN treatment and this adversity was protected by SBN post-treatment. Further, the fall in the activities of ATPases and increase in the levels of hydroxyproline and collagen observed in the liver tissue of DMN treated rats was prevented and reversed back toward normalcy by SBN post-treatment. Recovery of rat liver tissue against DMN-induced hepatocellular necrosis, inflammatory changes and hepatic fibrosis by SBN treatment is also confirmed by both H & E and Masson's trichrome stained histopathological evaluation of liver tissue. In conclusion, SBN exhibit hepatoprotective, antioxidant, free radical scavenging, membrane stabilizing and anti-fibrotic activity against DMN-induced hepatic fibrosis suggesting that it may be useful as a therapeutic agent toward amelioration of hepatic fibrosis.

Endothelin-1 derived from spleen-activated Rho-kinase pathway in rats with secondary biliary cirrhosis

AIM

  Splenectomy or partial splenic embolism has been reported to improve liver function in patients with hypersplenism and liver dysfunction. The aim of this study was to investigate the mechanism of improvement after splenectomy.

METHODS

  Liver cirrhosis was induced by bile duct ligation (BDL). Rats underwent sham operation, splenectomy (Sp group), BDL, or BDL plus splenectomy (BDL + Sp group), and were subjected to experiments at 2 weeks after the operation. Portal venous pressure (PVP) and hepatic tissue blood flow (HTBF) were measured in each group. The plasma concentration of endothelin-1 (ET-1) and endothelial nitric oxide synthase (eNOS), RhoA and Rho-kinase expressions were studied.

RESULTS

  There were significant differences in PVP (17.9 ± 0.91 vs 23.3 ± 3.91 cmH(2) O; P < 0.01) and HTBF (16.6 ± 1.72 vs 13.3 ± 1.82 mL/min; P < 0.01) between the BDL + Sp and BDL groups. In the liver of BDL rats, eNOS phosphorylation and NOx levels were decreased, accompanied by RhoA activation compared with the BDL + Sp group. Splenectomy decreased serum ET-1 levels, RhoA activation and consequently increased eNOS phosphorylation.

CONCLUSION

  ET-1 derived from the spleen might increase intrahepatic resistance by downregulating Rho signaling in liver cirrhosis. Splenectomy for splenomegaly in liver cirrhosis might partially improve liver function by enhancing intrahepatic microcirculation.

Cyclin E1 controls proliferation of hepatic stellate cells and is essential for liver fibrogenesis in mice

Liver fibrogenesis is associated with the transition of quiescent hepatocytes and hepatic stellate cells (HSCs) into the cell cycle. Exit from quiescence is controlled by E-type cyclins (cyclin E1 [CcnE1] and cyclin E2 [CcnE2]). Thus, the aim of the current study was to investigate the contribution of E-type cyclins for liver fibrosis in man and mice. Expression of CcnE1, but not of its homolog, CcnE2, was induced in fibrotic and cirrhotic livers from human patients with different etiologies and in murine wild-type (WT) livers after periodical administration of the profibrotic toxin, CCl(4). To further evaluate the potential function of E-type cyclins for liver fibrogenesis, we repetitively treated constitutive CcnE1(-/-) and CcnE2(-/-) knock-out mice with CCl(4) to induce liver fibrosis. Interestingly, CcnE1(-/-) mice were protected against CCl(4)-mediated liver fibrogenesis, as evidenced by reduced collagen type I α1 expression and the lack of septum formation. In contrast, CcnE2(-/-) mice showed accelerated fibrogenesis after CCl(4) treatment. We isolated primary HSCs from WT, CcnE1(-/-), and CcnE2(-/-) mice and analyzed their activation, proliferation, and survival in vitro. CcnE1 expression in WT HSCs was maximal when they started to proliferate, but decreased after the cells transdifferentiated into myofibroblasts. CcnE1(-/-) HSCs showed dramatically impaired survival, cell-cycle arrest, and strongly reduced expression of alpha smooth muscle actin, indicating deficient HSC activation. In contrast, CcnE2-deficient HSCs expressed an elevated level of CcnE1 and showed enhanced cell-cycle activity and proliferation, compared to WT cells.

CONCLUSIONS

CcnE1 and CcnE2 have antagonistic roles in liver fibrosis. CcnE1 is indispensable for the activation, proliferation, and survival of HSCs and thus promotes the synthesis of extracellular matrix and liver fibrogenesis.

Ca(2+) /calmodulin- dependent protein kinase II mediates transforming growth factor-β-induced hepatic stellate cells proliferation but not in collagen α1(I) production

AIM

  Hepatic stellate cells (HSC) are the major players in hepatic fibrosis. As a most potent mitogen, transforming growth factor-β (TGF-β) strongly activates HSC and increases intracellular Ca(2+) concentration. Here, we assessed the potential role of Ca(2+) /calmodulin-dependent protein kinase II (CaMKII), a main downstream effector of the Ca(2+) signal in liver fibrogenesis cascade.

METHODS

  A human immortal HSC cell line, LX-2, and primary rat hepatic stellate cells were used in current study. CaMKII blockage and Akt inhibition were performed by KN-93/CaMKIIα siRNA and LY294002, respectively. HSC proliferation was detected by 5-bromodeoxyuridine incorporation assay. Real-time polymerase chain reaction, western blot and enzyme-linked immunosorbent assay were used to measure mRNA, cellular protein and protein in medium, respectively. Procollagen α1(I) expression was detected by immunocytochemistry. The role of CaMKII on TGF-β/Smad-induced collagen α1(I) expression was determined by (CAGA)(12) -MLP luciferase activity assay.

RESULTS

  TGF-β dramatically increased CaMKII mRNA, and total and phosphorylated CaMKII expression. KN-93 and CaMKIIα siRNA suppressed TGF-β-mediated HSC proliferation. CaMKII interruption blocked TGF-β-elicited Akt activation. LY294002 arrested HSC proliferation and collagen α1(I) production but had no effect on CaMKII. Furthermore, CaMKII led to increased p21 and p27 expression. KN-93 and CaMKIIα siRNA inhibited TGF-β-induced and basal collagen α1(I) production but had no effect on the activity of (CAGA)(12) -MLP luciferase in response to TGF-β stimulation.

CONCLUSION

  CaMKII is a pivotal signal in TGF-β-induced fibrogenic cascades by means of stimulating HSC proliferation, and involved in a basal collagen production. Therefore, CaMKII will be a potentially effective target in the development of therapeutic intervention strategies to attenuate hepatic fibrosis.

Hepatic stimulator substance alleviates toxin-induced and immune-mediated liver injury and fibrosis in rats

BACKGROUND

Liver fibrosis is a common scarring response to chronic liver injury. It is a precursor to cirrhosis and liver carcinoma. Hepatic stimulator substance (HSS), a known liver-specific but species-nonspecific growth factor, has been shown to protect hepatocytes from various toxins.

METHODS

We have investigated the effects of HSS therapy on carbon tetrachloride (CCl(4))-induced and porcine-serum-mediated hepatic injury and fibrosis. We hypothesize that HSS might attenuate liver injury and fibrosis by suppressing oxidative stress, down-regulating profibrogenic factors, and blocking HSCs activation.

RESULTS

This report demonstrated that HSS therapy diminished α-smooth muscle actin expression, decreased intrahepatic reactive oxygen species (ROS) level, and down-regulated transforming growth factor (TGF)-β1, platelet-derived growth factor (PDGF)-BB, and tissue inhibitor of metalloproteinase (TIMP)-1 expression. In addition, HSS treatment significantly protected the liver from injury by improving liver function tests and histological architecture of the liver.

CONCLUSIONS

These results provided novel insights into the mechanisms of HSS in the protection of the liver. Our results suggested that HSS might be a therapeutic antifibrotic agent for the treatment of liver fibrosis.

Oral administration of recombinant adeno-associated virus-mediated bone morphogenetic protein-7 suppresses CCl(4)-induced hepatic fibrosis in mice

Fibrogenesis and hepatocyte degeneration are the main pathological processes in chronic liver diseases. Transforming growth factor-β1 (TGF-β1) is the key profibrotic cytokine in hepatic fibrosis. Bone morphogenetic protein-7 (BMP-7) is a potent antagonist of TGF-β1 and an antifibrotic factor. In this study, we generated a recombinant adeno-associated virus carrying BMP-7 (AAV-BMP-7) and tested its ability to suppress carbon tetrachloride (CCl(4))-induced hepatic fibrosis when orally administered to mice. Our results show that the ectopic expression of BMP-7 in gastrointestinal (GI) mucosa due to the AAV-BMP-7 administration led to the long-term elevation of serum BMP-7 concentrations and resulted in the drastic amelioration of CCl(4)-induced hepatic fibrosis in BALB/c mice. Immunostaining for α-smooth muscle actin (α-SMA) and desmin demonstrated that AAV-BMP-7 inhibited the activation of hepatic stellate cells (HSCs) in the fibrotic mouse liver. Moreover, the ectopic expression of BMP-7 promoted hepatocyte proliferation, as confirmed by an increase in the amount of proliferating cell nuclear antigen (PCNA)-positive hepatocytes in the mice that received AAV-BMP-7. Our results clearly indicate that BMP-7 is capable of inhibiting hepatic fibrosis and promoting hepatocyte regeneration. We suggest that oral AAV-BMP-7 could be developed into a safe, simple, and effective therapy for hepatic fibrosis.

Thyroid and Hepatic Haemodynamic Alterations among Egyptian Children with Liver Cirrhosis

Background. Alterations in thyroid hormones regulation and metabolism are frequently observed in patients with cirrhosis. Aims. To assess alterations in thyroid volume (TV), haemodynamics, and hormones in patients with cirrhosis and their relation to hepatic arterial haemodynamics, and disease severity. Methods. Forty cirrhotic patients were compared to 30 healthy subjects regarding TV, free triiodiothyronine (fT₃), free tetraiodothyronine (fT₄), thyroid stimulating hormone (TSH), and pulsatility and resistance indices in the inferior thyroid and hepatic arteries. Results. TV (P = 0.042), thyroid volume standard deviation score (TVSDS, P = 0.001), Inferior Thyroid Artery Pulsatility Index (ITAPI, P = 0.001), Inferior Thyroid Artery Resistance Index (ITARI, P = 0.041), Hepatic Artery Pulsatility Index (HAPI, P = 0.029) and Hepatic Artery Resistance Index (HARI, P = 0.035) were higher among cases being highest in Child-C patients. FT₃ was lower in patients than controls (P = 0.001) and correlated negatively with ITAPI (r = −0.71, P = 0.021) and ITARI (r = −0.79, P = 0.011). ITAPI and ITARI correlated directly with HAPI and HARI (r = 0.62, P = 0.03, and r = 0.42, P = 0.04, resp.). Conclusions. Thyroid is involved in the haemodynamic alterations of cirrhosis. Routine study of thyroid by Doppler and assessment of thyroid functions should be performed in patients with cirrhosis to offer proper treatment if needed.

Lentiviral vector-mediated down-regulation of IL-17A receptor in hepatic stellate cells results in decreased secretion of IL-6

AIM: To investigate the mechanism of interleukin (IL)-6 secretion through blocking the IL-17A/IL-17A receptor (IL-17RA) signaling pathway with a short hairpin RNA (shRNA) in hepatic stellate cells (HSCs) in vitro.

METHODS: HSCs were derived from the livers of adult male Sprague-Dawley rats. IL-6 expression was evaluated using real-time quantitative polymerase chain reaction and enzyme linked immunosorbent assay. The phosphorylation activity of p38 mitogen activated protein kinases (MAPK) and extracellular regulated protein kinases (ERK) 1/2 upon induction by IL-17A and suppression by IL-17RA shRNA were examined using Western blotting.

RESULTS: IL-6 expression induced by IL-17A was significantly increased compared to control in HSCs (P < 0.01 in a dose-dependent manner). Suppression of IL-17RA using lentiviral-mediated shRNA inhibited IL-6 expression induced by IL-17A compared to group with only IL-17A treatment (1.44 ± 0.17 vs 4.07 ± 0.43, P < 0.01). IL-17A induced rapid phosphorylation of p38 MAPK and ERK1/2 after 5 min exposure, and showed the strongest levels of phosphorylation of p38 MAPK and ERK1/2 at 15 min in IL-17A-treated HSCs. IL-6 mRNA expression induced by IL-17A (100 ng/mL) for 3 h exposure was inhibited by preincubation with specific inhibitors of p38 MAPK (SB-203580) and ERK1/2 (PD-98059) compared to groups without inhibitors preincubation (1.67 ± 0.24, 2.01 ± 0.10 vs 4.08 ± 0.59, P < 0.01). Moreover, Lentiviral-mediated IL-17RA shRNA 1 inhibited IL-17A-induced IL-6 mRNA expression compared to random shRNA in HSCs (1.44 ± 0.17 vs 3.98 ± 0.68, P < 0.01). Lentiviral-mediated IL-17RA shRNA 1 inhibited phosphorylation of p38 MAPK and ERK1/2 induced by 15 min IL-17A (100 ng/mL) exposure.

CONCLUSION: Down-regulation of the IL-17RA receptor by shRNA decreased IL-6 expression induced by IL-17A via p38 MAPK and ERK1/2 phosphorylation in HSCs. Suppression of IL-17RA expression may be a strategy to reduce the inflammatory response induced by IL-17A in the liver.

High mobility group box 1 activates Toll like receptor 4 signaling in hepatic stellate cells

AIMS

The aim of the present study was to investigate the effect of high mobility group box 1 (HMGB1), a damage pattern molecule that signals the presence of necrosis, on TLR4 signaling in hepatic stellate cells (HSC).

MAIN METHODS

Immortalized mouse HSC lines JS1, JS2, and JS3 that were either TLR4(+/+), TLR4(-/-), or MyD88(-/-) were transfected with NF-κB or AP-1 responsive luciferase reporter plasmids, followed by stimulation with 100 ng/ml lipopolysacchride (the exogenous TLR4 ligand) or 100 ng/ml HMGB1. The activation of NF-κB or AP-1 activities was determined by a dual-luciferase reporter assay system. The cells were also stimulated with LPS or HMGB1 and collected for the determination of chemotactic cytokine MCP-1 mRNA or proteins secretion. In a separate experiment, the cells were co-stimulated with 10 μg/ml TGF-β1 and LPS or HMGB1 and collected for assessment of fibrogenic mRNA and protein expression.

KEY FINDINGS

HMGB1 stimulation markedly up-regulated MCP-1 mRNA expression and protein secretion, and enhanced TGF-β1-stimulated collagen α2(I) and α-SMA expression in JS1 cells. This was associated with enhanced activation of NF-κB and AP-1 responsive luciferase reporters. On the contrary, JS2 and JS3 cells were hyporesponsive to both LPS and HGMB1 stimulation compared to JS1 cells.

SIGNIFICANCE

As an endogenous ligand of TLR4, HMGB1 activates TLR4 signaling in HSCs to enhance their inflammatory phenotype, indicating that TLR4 signaling need not rely solely on gut-derived LPS for activation during liver injury. HMGB1 also has a synergistic effect with TGF-β1 to stimulate fibrogenic protein expression, which is likely to be TLR4 dependent.

Zinc finger protein A20 protects rats against chronic liver allograft dysfunction

AIM: To investigate the effect of zinc finger protein A20 on chronic liver allograft dysfunction in rats.

METHODS: Allogeneic liver transplantation from DA rats to Lewis rats was performed. Chronic liver allograft dysfunction was induced in the rats by administering low-dose tacrolimus at postoperative day (POD) 5. Hepatic overexpression of A20 was achieved by recombinant adenovirus (rAd.)-mediated gene transfer administered intravenously every 10 d starting from POD 10. The recipient rats were injected with physiological saline, rAdEasy-A20 (1 × 10⁹ pfu/30 g weight) or rAdEasy (1 × 10⁹ pfu/30 g weight) every 10 d through the tail vein for 3 mo starting from POD 10. Liver tissue samples were harvested on POD 30 and POD 60.

RESULTS: Liver-transplanted rats treated with only tacrolimus showed chronic allograft dysfunction with severe hepatic fibrosis. A20 overexpression ameliorated the effects on liver function, attenuated liver allograft fibrosis and prolonged the survival of the recipient rats. Treatment with A20 suppressed hepatic protein production of tumor growth factor (TGF)-β1, interleukin-1β, caspase-8, CD40, CD40L, intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and E-selectin. A20 treatment suppressed liver cell apoptosis and inhibited nuclear factor-κB activation of Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs) and hepatic stellate cells (HSCs), and it subsequently decreased cytokine mRNA expression in KCs and LSECs and reduced the production of TGF-β1 in HSCs.

CONCLUSION: A20 might prevent chronic liver allograft dysfunction by re-establishing functional homeostasis of KCs, LSECs and HSCs.

Evaluation of the Chinese Medicinal Herb, Graptopetalum paraguayense, as a Therapeutic Treatment for Liver Damage in Rat Models

The incidence of cirrhosis is rising due to the widespread occurrence of chronic hepatitis, as well as the evident lack of an established therapy for hepatic fibrosis. In the search for hepatoprotective therapeutic agents, Graptopetalum paraguayense (GP) showed greater cytotoxicity toward hepatic stellate cells than other tested herbal medicines. Histopathological and biochemical analyses suggest that GP treatment significantly prevented DMN-induced hepatic inflammation and fibrosis in rats. Microarray profiling indicated that expression of most of metabolism- and cell growth and/or maintenance-related genes recovered to near normal levels following GP treatment as classified by gene ontology and LSM analysis, was observed. ANOVA showed that expression of 64% of 256 liver damage-related genes recovered significantly after GP treatment. By examining rat liver samples with Q-RT-PCR, five liver damage-related genes were identified. Among them, Egr1 and Nrg1 may serve as necroinflammatory markers, and Btg2 may serve as a fibrosis marker. Oldr1 and Hmgcs1 were up- and down-regulated markers, respectively. A publicly accessible website has been established to provide access to these data Identification of 44 necroinflammation-related and 62 fibrosis-related genes provides useful insight into the molecular mechanisms underlying liver damage and provides potential targets for the rational development of therapeutic drugs such as GP.

Artificial neural network aided non-invasive grading evaluation of hepatic fibrosis by duplex ultrasonography

BACKGROUND

Artificial neural networks (ANNs) are widely studied for evaluating diseases. This paper discusses the intelligence mode of an ANN in grading the diagnosis of liver fibrosis by duplex ultrasonogaphy.

METHODS

239 patients who were confirmed as having liver fibrosis or cirrhosis by ultrasound guided liver biopsy were investigated in this study. We quantified ultrasonographic parameters as significant parameters using a data optimization procedure applied to an ANN. 179 patients were typed at random as the training group; 60 additional patients were consequently enrolled as the validating group. Performance of the ANN was evaluated according to accuracy, sensitivity, specificity, Youden's index and receiver operating characteristic (ROC) analysis.

RESULTS

5 ultrasonographic parameters; i.e., the liver parenchyma, thickness of spleen, hepatic vein (HV) waveform, hepatic artery pulsatile index (HAPI) and HV damping index (HVDI), were enrolled as the input neurons in the ANN model. The sensitivity, specificity and accuracy of the ANN model for quantitative diagnosis of liver fibrosis were 95.0%, 85.0% and 88.3%, respectively. The Youden's index (YI) was 0.80.

CONCLUSIONS

The established ANN model had good sensitivity and specificity in quantitative diagnosis of hepatic fibrosis or liver cirrhosis. Our study suggests that the ANN model based on duplex ultrasound may help non-invasive grading diagnosis of liver fibrosis in clinical practice.

The role of hepatic stellate cells in the regulation of T-cell function and the promotion of hepatocellular carcinoma

Hepatic stellate cells (HSCs) have immunosuppressive abilities and may be responsible for the occurrence and development of hepatocellular carcinoma (HCC). However, the mechanisms through which HSCs affect T-cell-mediated immune responses remain unclear. The aim of this study was to elucidate these mechanisms. We examined the effect of HSCs on T-cell proliferation and apoptosis, regulatory T cells (Treg cells) and T-cell-mediated cytotoxicity using mixed leukocyte reactions (MLRs). Furthermore, we examined the cytokines present in the supernatant and the effect of this supernatant on the proliferation and migration of cancer cells. Finally, we examined the effect of HSCs on HCC cells in vivo. We found that activated HSCs induced T-cell hyporesponsiveness, accelerated activated T-cell apoptosis, increased the number of Treg cells and inhibited T-cell-mediated cytotoxicity. HSCs also enhanced the expression of some cytokines and promoted the proliferation and migration of cancer cells. Furthermore, activated HSCs were able to induce HCC proliferation and Treg cells expansion in vivo. Activated HSCs may induce T cell anergy, thereby facilitating the immunologic escape of HCC cells.

The role of hepatic stellate cells in the regulation of T-cell function and the promotion of hepatocellular carcinoma

Hepatic stellate cells (HSCs) have immunosuppressive abilities and may be responsible for the occurrence and development of hepatocellular carcinoma (HCC). However, the mechanisms through which HSCs affect T-cell-mediated immune responses remain unclear. The aim of this study was to elucidate these mechanisms. We examined the effect of HSCs on T-cell proliferation and apoptosis, regulatory T cells (Treg cells) and T-cell-mediated cytotoxicity using mixed leukocyte reactions (MLRs). Furthermore, we examined the cytokines present in the supernatant and the effect of this supernatant on the proliferation and migration of cancer cells. Finally, we examined the effect of HSCs on HCC cells in vivo. We found that activated HSCs induced T-cell hyporesponsiveness, accelerated activated T-cell apoptosis, increased the number of Treg cells and inhibited T-cell-mediated cytotoxicity. HSCs also enhanced the expression of some cytokines and promoted the proliferation and migration of cancer cells. Furthermore, activated HSCs were able to induce HCC proliferation and Treg cells expansion in vivo. Activated HSCs may induce T cell anergy, thereby facilitating the immunologic escape of HCC cells.