TGFbeta1 in liver fibrosis: time to change paradigms?

Royal Jelly and Chlorella vulgaris Mitigate Gibberellic Acid-Induced Cytogenotoxicity and Hepatotoxicity in Rats via Modulation of the PPARα/AP-1 Signaling Pathway and Suppression of Oxidative Stress and Inflammation

Gibberellic acid (GA3) is a well-known plant growth regulator used in several countries, but its widespread use has negative effects on both animal and human health. The current study assesses the protective effect of royal jelly (RJ) and Chlorella vulgaris (CV) on the genotoxicity and hepatic injury induced by GA3 in rats. Daily oral administration of 55 mg/kg GA3 to rats for 6 constitutive weeks induced biochemical and histopathological changes in the liver via oxidative stress and inflammation. Co-administration of 300 mg/kg RJ or 500 mg/kg CV with GA3 considerably ameliorated the serum levels of AST (aspartate aminotransferase), ALT (alanine aminotransferase), ALP (alkaline phosphatase), γGT (gamma-glutamyl transferase), total bilirubin, and albumin. Lowered malondialdehyde, tumor necrosis factor α (TNF-α), and nuclear factor κB (NF-κB) levels along with elevated SOD (superoxide dismutase), CAT (catalase), and GPx (glutathione peroxidase) enzyme activities indicated the antioxidant and anti-inflammatory properties of both RJ and CV. Also, they improved the histological structure and reduced cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expressions along with up-regulating peroxisome proliferator activated receptor α (PPARα) and down-regulating activator protein 1 (AP-1) gene expression. Additionally, chromosomal abnormalities and mitotic index were nearly normalized after treatment with RJ and CV. In conclusion, RJ and CV can protect against GA3-induced genotoxicity and liver toxicity by diminishing oxidative stress and inflammation, and modulating the PPARα/AP-1 signaling pathway.

Single-cell RNA sequencing identifies a population of human liver-type ILC1s

Group 1 innate lymphoid cells (ILCs) comprise a heterogeneous family of cytotoxic natural killer (NK) cells and ILC1s. We identify a population of "liver-type" ILC1s with transcriptional, phenotypic, and functional features distinct from those of conventional and liver-resident NK cells as well as from other previously described human ILC1 subsets. LT-ILC1s are CD49a+CD94+CD200R1+, express the transcription factor T-BET, and do not express the activating receptor NKp80 or the transcription factor EOMES. Similar to NK cells, liver-type ILC1s produce IFN-γ, TNF-α, and GM-CSF; however, liver-type ILC1s also produce IL-2 and lack perforin and granzyme-B. Liver-type ILC1s are expanded in cirrhotic liver tissues, and they can be produced from blood-derived ILC precursors in vitro in the presence of TGF-β1 and liver sinusoidal endothelial cells. Cells with similar signature and function can also be found in tonsil and intestinal tissues. Collectively, our study identifies and classifies a population of human cross-tissue ILC1s.

The construction of preclinical evidence for the treatment of liver fibrosis with quercetin: A systematic review and meta-analysis

Quercetin (3,3',4',5,7-pentahydroxyflavone), a flavonoid, is widely found in fruits and vegetables and exerts broad-spectrum pharmacological effects in the liver. Many studies have explored the bioactivity of quercetin in the treatment of liver fibrosis. Hence, through a systematic review and biological mechanism evaluation, this study aimed to construct a body of preclinical evidence for the treatment of liver fibrosis using quercetin. The literature used in this study was mainly obtained from four databases, and the SYRCLE list (10 items) was used to evaluate the quality of the included literature. A meta-analysis of HA, LN, and other indicators was performed via STATA 15.0 software. Subgroup analyses based on animal species and model protocol were performed to further obtain detailed results. Moreover, the therapeutic mechanism of quercetin was summarized in a directed network form based on a comprehensive search of the literature. After screening, a total of 14 articles (comprising 15 studies) involving 254 animals were included. The results from the analysis showed that the corresponding liver function indexes, such as the levels of HA and LN, were significantly improved in the quercetin group compared with the model group, and liver function, such as the levels of AST and ALT, were also improved in the quercetin group. The species- and model-based subgroup analyses of AST and ALT revealed that quercetin exerts a significant effect. The therapeutic mechanism of quercetin was shown to be related to multiple pathways involving anti-inflammatory and antioxidant activities and lipid accumulation, including regulation of the TGF-β, α-SMA, ROS, and P-AMPK pathways. The results showed that quercetin exerts an obvious effect on liver fibrosis, and more prominent improvement effects on liver function and liver fibrosis indicators were obtained with a dose of 5-200 mg during a treatment course ranging from 4 to 8 weeks. Quercetin might be a promising therapeutic for liver fibrosis.

Comparative study on effect of mesenchymal stem cells and endothelial progenitor cells on treatment of experimental CCL4-induced liver fibrosis

BACKGROUND

We speculated impacts of BM-MSCs and UC-EPCs on reversal of hepatic injury induced by carbon tetrachloride (CCl4). Fifty adult rats were divided into five groups: control group, CCl4A group, CCl4B group, CCl4/BM-MSCs group and CCl4/UC-EPCs group. Blood samples were driven to measure concentration of albumin and ALT. Quantitative expression of HGF, TGF-β, MMP-2, and VEGF were assessed by PCR. Histological and immunohistochemistry examination of the liver tissue were performed.

RESULTS

There was elevating albumin (p < .05) and reducing ALT (p < .05) concentrations in groups treated with BM-MSCs and UC-EPCs compared to untreated CCL4A&B groups. UC-EPCs treated group have significantly higher MMP-2 and VEGF (p < .01) genes expression than BM-MSCs treated group. Furthermore, UC-EPCs were more valuable than BMMSCs in increasing gene expression of HGF (p < .05) and immunohistochemistry of α-SMA and Ki-67 (p < .01). BM-MSCs have significantly lower TGF-β (p < .00) compared to UC-EPCs.

CONCLUSION

This study highlighted on liver regeneration role of both UC-EPCs and BM-MSCs in liver fibrosis.

Crocetin Protected Human Hepatocyte LO2 Cell From TGF-β-Induced Oxygen Stress and Apoptosis but Promoted Proliferation and Autophagy via AMPK/m-TOR Pathway

Objective

To investigate the protective effects of crocetin against transforming growth factor-β (TGF-β)—induced injury in LO2 cells.

Methods

Human hepatocyte LO2 cells were pre-treated with crocetin (10 μM) for 6, 12, and 24 h, and then induced by TGF-β. Proliferation, oxidative stress, apoptosis, autophagy, and related proteins were assessed.

Results

Crocetin pre-treating promoted proliferation but suppressed apoptosis in TGF-β-induced LO2 cells. Crocetin protected LO2 cells from TGF-β-induced inflammation and oxygen stress by reducing reactive oxygen species (ROS) and malondialdehyde (MDA) but enhancing superoxide dismutase (SOD) and glutathione (GSH). Autophagy was suppressed in TGF-β but crocetin promoted autophagy in LO2 cells by mediating Adenosine 5'-monophosphate—activated protein kinase (AMPK)/mammalian target of rapamycin (m-TOR) signaling pathway via upregulating p-AMPK and p-Beclin-1 but downregulating p-mTOR.

Conclusions

Crocetin protected LO2 cells from TGF-β-induced damage by promoting proliferation and autophagy, and suppressing apoptosis and anti-inflammation via regulation of AMPK/m-TOR signaling pathway.

Bone Marrow-derived Mesenchymal Stem Cells Reverse Hepatic Fibrosis, Improved Vascularity, and Attenuate the Apoptosis in Carbon Tetrachloride-induced Hepatic Fibrosis Experimental Rats

Background: Liver fibrosis is a sequel of different chronic inflammatory diseases. The most effective treatment for end-stage liver fibrosis is liver transplantation; but the shortage of donor organs, immunological rejection, surgical complications, and high medical costs limit the transplantation. That’s why we are in argent need to develop new strategies in treatment.  Objectives: to evaluate the role of MSCs in regenerating liver cells and reverse hepatic fibrosis. Materials and Methods: 30 Animals were randomly divided into three groups (10 animals each): group 1: a negative control; group 2: induced liver fibrosis (pathological control).; group 3: induced liver fibrosis that received undifferentiated BM MSCs (3×106 cells/ml intraperitoneally/single dose); The extent of fibrosis, vascularization, and inflammation and hepatic cell apoptosis were evaluated together with assessment of liver functions. Results: The MSCs treated group showed significant improvement of liver functions, and attenuation of fibrosis histopathologicaly and down regulate the expression of TGF ß versus the induced fibrosis group. inflammatory marker(TNF,IL-6) were down regulated and vascularity was restored in MSCs treated group  compared to CCL4 induced fibrosis rats.  Conclusion: MSCs provide promising therapeutic agents in treatment of liver fibrosis.

Electrochemical Biosensors for Cytokine Profiling: Recent Advancements and Possibilities in the Near Future

Cytokines are soluble proteins secreted by immune cells that act as molecular messengers relaying instructions and mediating various functions performed by the cellular counterparts of the immune system, by means of a synchronized cascade of signaling pathways. Aberrant expression of cytokines can be indicative of anomalous behavior of the immunoregulatory system, as seen in various illnesses and conditions, such as cancer, autoimmunity, neurodegeneration and other physiological disorders. Cancer and autoimmune diseases are particularly adept at developing mechanisms to escape and modulate the immune system checkpoints, reflected by an altered cytokine profile. Cytokine profiling can provide valuable information for diagnosing such diseases and monitoring their progression, as well as assessing the efficacy of immunotherapeutic regiments. Toward this goal, there has been immense interest in the development of ultrasensitive quantitative detection techniques for cytokines, which involves technologies from various scientific disciplines, such as immunology, electrochemistry, photometry, nanotechnology and electronics. This review focusses on one aspect of this collective effort: electrochemical biosensors. Among the various types of biosensors available, electrochemical biosensors are one of the most reliable, user-friendly, easy to manufacture, cost-effective and versatile technologies that can yield results within a short period of time, making it extremely promising for routine clinical testing.

Modulation of Liver Inflammation and Fibrosis by Interleukin-37

Background and Aims: Chronic inflammation induces liver fibrosis, cirrhosis and potentially liver cancer. Kupffer cells modulate hepatic stellate cells by secreting immunologically active proteins as TGF-β. TGF-β promotes liver fibrosis via the activation of Sma- and Mad-related protein 3. IL-37 broadly suppresses innate and adaptive immune responses. Intracellular IL-37 interacts with Smad3. We hypothesize that IL-37 downregulates the activation of hepatic Kupffer and stellate cells and interferes with the TGF-β signaling cascade to modulate liver fibrogenesis. Methods: The role of IL-37 on liver inflammation and fibrogenesis was assessed in three mouse models as well as isolated Kupffer- and stellate cells. Serum IL-37 was tested by ELISA in a clinical cohort and correlated with liver disease severity. Results: Transgene expression of IL-37 in mice extends survival, reduces hepatic damage, expression of early markers of fibrosis and histologically assessed liver fibrosis after bile duct ligation. IL-37tg mice were protected against CCl4-induced liver inflammation. Colitis-associated liver inflammation and fibrosis was less severe in IL-10 knockout IL-37tg mice. Spontaneous and LPS/TGF-β-induced cytokine release and profibrogenic gene expression was lower in HSC and KC isolated from IL-37tg mice and IL-37 overexpressing, IL-1β stimulated human LX-2 stellate cells. However, administration of recombinant human IL-37 did not modulate fibrosis pathways after BDL in mice, LX2 cells or murine HSCs. In a large clinical cohort, we observed a positive correlation of serum IL-37 levels with disease severity in liver cirrhosis. Conclusions: Predominantly intracellular IL-37 downregulates liver inflammation and fibrosis. The correlation of serum IL-37 with disease severity in cirrhosis suggests its potential as a novel target modulating the course of liver fibrosis.

Cyclam-Modified Polyethyleneimine for Simultaneous TGFβ siRNA Delivery and CXCR4 Inhibition for the Treatment of CCl4-Induced Liver Fibrosis

BACKGROUND

Liver fibrosis is a chronic liver disease with excessive production of extracellular matrix proteins, leading to cirrhosis, hepatocellular carcinoma, and death.

PURPOSE

This study aimed at the development of a novel derivative of polyethyleneimine (PEI) that can effectively deliver transforming growth factor β (TGFβ) siRNA and inhibit chemokine receptor 4 (CXCR4) for TGFβ silencing and CXCR4 Inhibition, respectively, to treat CCl₄-induced liver fibrosis in a mouse model.

METHODS

Cyclam-modified PEI (PEI-Cyclam) was synthesized by incorporating cyclam moiety into PEI by nucleophilic substitution reaction. Gel electrophoresis confirmed the PEI-Cyclam polyplex formation and stability against RNAase and serum degradation. Transmission electron microscopy and zeta sizer were employed for the morphology, particle size, and zeta potential, respectively. The gene silencing and CXCR4 targeting abilities of PEI-Cyclam polyplex were evaluated by luciferase and CXCR4 redistribution assays, respectively. The histological and immunohistochemical staining determined the anti-fibrotic activity of PEI-Cyclam polyplex. The TGFβ silencing of PEI-Cyclam polyplex was authenticated by Western blotting.

RESULTS

The ¹H NMR of PEI-Cyclam exhibited successful incorporation of cyclam content onto PEI. The PEI-Cyclam polyplex displayed spherical morphology, positive surface charge, and stability against RNAse and serum degradation. Cyclam modification decreased the cytotoxicity and demonstrated CXCR4 antagonistic and luciferase gene silencing efficiency. PEI-Cyclam/siTGFβ polyplexes decreased inflammation, collagen deposition, apoptosis, and cell proliferation, thus ameliorating liver fibrosis. Also, PEI-Cyclam/siTGFβ polyplex significantly downregulated α-smooth muscle actin, TGFβ, and collagen type III.

CONCLUSION

Our findings validate the feasibility of using PEI-Cyclam as a siRNA delivery vector for simultaneous TGFβ siRNA delivery and CXCR4 inhibition for the combined anti-fibrotic effects in a setting of CCl₄-induced liver fibrosis.

Hyperoside protects against heart failure-induced liver fibrosis in rats

Heart failure (HF) is an end-stage of various serious cardiovascular diseases, which causes liver injury. Hyperoside has been reported to exert protective effect on liver injury and fibrosis. However, the role and related mechanisms of hyperoside in HF-induced liver fibrosis are still unclear. In the current study, we established a model of HF via aortocaval fistula (ACF) in rats in vivo. Hyperoside treatment in ACF rats increased cardiac output, the maximum peak rate of rise/fall in left ventricular pressure (+dP/dt, -dP/dt) and LV ejection fraction (LVEF), decreased LV end-systolic pressure (LVESP), LV end-diastolic pressure (LVEDP) and LV end-systolic volume (LVESV), and reduced heart weight/body weight ratio in a dose-dependent manner. Moreover, hyperoside could attenuate liver fibrosis and injury in ACF rats, as evidenced by reduction of fibrosis area and hydroxyproline content, amelioration of edema and degeneration of liver cell vacuoles, and inhibition of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) levels. Further, α-smooth-muscle actin (α-SMA), collagen I, profibrotic factor-connective tissue growth factor (CTGF), matrix metalloproteinase-2 (MMP2) and MMP9 levels were down-regulated in hyperoside-treated ACF rats. Additionally, hyperoside inhibited the activation of TGF-β1/Smad pathway. Finally, we confirmed that hyperoside suppressed TGF-β1-mediated hepatic stellate cell activation in vitro. Collectively, hyperoside showed a suppressive role in HF-induced liver fibrosis and injury.

Histological and biochemical changes induced by gibberellic acid in the livers of pregnant albino rats and their offspring: ameliorative effect of Nigella sativa

Gibberellic acid (GA3), a plant growth regulator, is widely used in agriculture in many countries to accelerate the growth of fruits and vegetables. We designed histological, immunohistochemical, and biochemical studies to evaluate the deleterious effects of GA3 on the livers of adult pregnant rats and their offspring and to assess the possible ameliorative effect of Nigella sativa Linn. (NsL.oil) against these effects. Twenty-four pregnant albino rats were utilized, randomly divided into four groups: The first group was used as a negative control group, while the second group (positive control group) was provided NsL.oil at a dose of 100 mg/kg of bodyweight. Animals in the third group (GA3 group) were provided 200 ppm of GA3 dissolved in distilled water from the 7th day of pregnancy until 1 day after delivery. Animals in the last group (GA3 + NsL.oil group) were provided GA3 and NsL-oil at the same doses as mentioned above. One day after delivery, each group of lactating mothers and their pups were sacrificed. Liver specimens were subjected to histopathological, immunohistochemical, and biochemical examinations. The livers of rats from the GA3 group showed various degenerative changes, being predominant in the livers of the mothers compared with the offspring. The pathological changes in the livers of the offspring suggested transplacental passage of GA3. The results reveal that GA3 ingestion induced a significant increase in alanine aminotransferase (ALT) and aspartate transaminase (AST) activities in the serum of both groups of mothers and their pups, with a significant increment in lipid peroxidation as evidenced by enhanced malondialdehyde (MDA) levels with significant decrements in superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) enzymatic activities in comparison with control groups in the liver of mothers and their offspring. Histopathological examination showed hydropic degeneration and inflammatory cellular infiltration. Additionally, there was fibrosis around the portal area. Moreover, immunolocalization revealed downregulation of the expression of the antiapoptotic marker Bcl-2 in hepatocytes and upregulation of the expression of the apoptotic marker Bax in the treated group. Concomitant use of NsL.oil along with GA3 exerted a considerable reversing effect on histopathological and biochemical changes in the livers of mother groups and their pups. The results of the present study highlight the consequences of exposure to GA3 during pregnancy on hepatic tissue in both mothers and their offspring. Furthermore, the study suggests use of NsL.oil as a potential protective strategy against GA3-induced liver toxicity.

Platelet TGF-β1 deficiency decreases liver fibrosis in a mouse model of liver injury

Transforming growth factor-β1 (TGF-β1) signaling in hepatic stellate cells (HSCs) plays a primary role in liver fibrosis, but the source of TGF-β1 is unclear. Because platelets are rich in TGF-β1, we examined the role of platelet TGF-β1 in liver fibrosis by challenging wild-type (WT) mice and mice deficient in platelet TGF-β1 (PF4CreTgfb1^f/f) with carbon tetrachloride (CCl₄), an inducer of acute hepatic injury and chronic fibrosis. CCl₄ elicited equivalent hepatic injury in WT and PF4CreTgfb1^f/f mice based on loss of cytochrome P450 (Cyp2e1) expression, observed at 6 hours and peaking at 3 days after CCl₄ challenge; PF4CreTgfb1^f/f mice exhibited less liver fibrosis than control mice. Activated platelets were observed during acute liver injury (6 hours), and WT mice with transient platelet depletion (thrombocytopenia) were partially protected from developing fibrosis compared with control mice (P = .01), suggesting an association between platelet activation and fibrosis. Transient increases in TGF-β1 levels and Smad2 phosphorylation signaling were observed 6 hours and 3 days, respectively, after CCl₄ challenge in WT, but not PF4CreTgfb1^f/f , mice, suggesting that increased TGF-β1 levels originated from platelet-released TGF-β1 during the initial injury. Numbers of collagen-producing HSCs and myofibroblasts were higher at 3 days and 36 days, respectively, in WT vs PF4CreTgfb1^f/f mice, suggesting that platelet TGF-β1 may have stimulated HSC transdifferentiation into myofibroblasts. Thus, platelet TGF-β1 partially contributes to liver fibrosis, most likely by initiating profibrotic signaling in HSCs and collagen synthesis. Further studies are required to evaluate whether blocking platelet and TGF-β1 activation during acute liver injury prevents liver fibrosis.

Exosomal Transmission of MicroRNA from HCV Replicating Cells Stimulates Transdifferentiation in Hepatic Stellate Cells

The mechanism by which hepatitis C virus (HCV) causes fibrosis and other chronic liver diseases remains poorly understood. Previously, we observed that HCV infection induces microRNA-192 (miR-192) expression, which in turn upregulates transforming growth factor β1 (TGF-β1) in hepatocytes. In this study, we aimed to determine the roles and mechanisms of HCV-induced miR-192 expression during chronic liver injury and fibrosis and to identify potential target of the liver disease. Noticeably, miR-192 is secreted and transmitted through exosomes from HCV-replicating hepatocytes into hepatic stellate cells (HSCs). Exosomal transferred miR-192 upregulated fibrogenic markers in HSCs through TGF-β1 upregulation, resulting in the activation and transdifferentiation of HSCs into myofibroblasts. Anti-miR-192 treatment of HCV-replicating hepatocytes efficiently reduced miR-192 levels in exosomes, downregulated miR-192 and fibrogenic marker levels in HSCs, and impeded transdifferentiation of the cells. In contrast, miR-192 mimic RNA treatment significantly increased miR-192 levels in exosomes from naive hepatocytes, increased miR-192 and fibrogenic marker expression in HSCs, and induced transdifferentiation of the cells. Notably, transdifferentiation of exosome-exposed HSCs was reversed following treatment with anti-miR-192 into the HSCs. This study revealed a novel mechanism of HCV-induced liver fibrosis and identified exosomal miR-192 as a major regulator and potential treatment target for HCV-mediated hepatic fibrosis.

The regulation of CIRBP by transforming growth factor beta during heat shock-induced testicular injury

BACKGROUND

Cold-inducible RNA-binding protein (CIRBP) is associated with cell stress. However, its upstream regulatory factors are still largely unknown.

OBJECTIVES

This study investigated whether CIRBP expression was regulated by transforming growth factor beta (TGF-β) during the process of heat-induced testicular damage.

MATERIALS AND METHODS

Ten male adult ICR mice were allocated to heat treatment (scrotal hyperthermia at 43 °C for 30 min, n = 5) and control group (n = 5); CIRBP and TGF-β1, TGF-β2, and TGF-β3 expression levels in the testis in mRNA and protein were analyzed. Then, we conducted in vivo and in vitro studies to investigate the regulatory effects of TGF-β on CIRBP. In the in vivo study, male adult ICR mice were subjected to testicular hyperthermia followed by a local testicular injection of TGF-β antagonist (non-selective TGF-β I/II receptor inhibitor, 5 μg or 10 μg). In the in vitro study, GC2-spd cells were cultured under 43 °C for 30 min or with different TGF-β isoforms (10 ng/mL), and CIRBP expression levels in the testis and GC2-spd cells were analyzed 24 and 48 h, respectively, after treatment.

RESULTS

As a result, heat treatment significantly downregulated the relative CIRBP mRNA and protein expression (p = 0.006 and 0.011), and significantly upregulated TGF-β2 and TGF-β3 expression levels (p = 0.022 and 0.04, for mRNA, and p = 0.001 for both protein levels). Local testicular injection of 10 μg TGF-β antagonist significantly attenuated heat-induced histological damage to the testes and CIRBP downregulation (p = 0.038). Furthermore, TGF-β2 and TGF-β3 significantly downregulated CIRBP mRNA and protein expression in GC2-spd cells (all p < 0.01), exerting a similar effect to heat treatment.

DISCUSSION AND CONCLUSION

Our in vivo and in vitro experiments demonstrated that heat-induced CIRBP downregulation in the testes was mediated by the upregulation of TGF-β. Further studies are needed to clarify the molecular mechanisms underlying these processes.

Effects of treatment with Maraviroc a CCR5 inhibitor on a human hepatic stellate cell line

After an acute liver damage, tissue regeneration repairs lesions with degradation of deposed fibrotic material, while mechanisms of tissue restoration are persistently activated following several repeated injuries, inducing deposition of extracellular matrix. (ECM). Factors responsible for ECM remodeling have been identified in a pathway involving a family of zinc-dependent enzyme matrix metalloproteinases (MMPs), together with tissue inhibitor of metalloproteinases (TIMPs). Recent experimental models suggested a role of CCR5 receptor in the genesis of liver fibrosis. Drawing from these background we decided to evaluate the effects of the treatment with the CCR5 inhibitor Maraviroc on LX-2, a human hepatic stellate cell line (HSC). Treatment with Maraviroc resulted in a block in S phase of LX-2 cells with increased expression levels of cyclin D1 and p21 while the expression of p53 was reduced. Treatment with Maraviroc was also able to block the accumulation of fibrillar collagens and extracellular matrix proteins (ECM), as demonstrated by the decrease of specific markers as Collagen type I, α-SMA, and TGF-β1. In addition we observed a down regulation of both metalloproteins (MMP-2, MMP-9), used for the degradation of the extracellular matrix and their inhibitors (TIMP-1, TIMP-2). The identification of a compound that may modulate the dynamic of liver fibrosis could be crucial in all chronic liver diseases. Maraviroc could play an important role because, in addition to its own anti-HIV activity, it could reduce the release of pro-inflammatory citokynes implicated in liver fibrogenesis.

Hepatoprotective activities of rosmarinic acid against extrahepatic cholestasis in rats

Though rosmarinic acid possesses nutritional, pharmaceutical, and toxic properties and shows therapeutic potential on liver diseases, its therapeutic effects against cholestatic liver diseases have not been proven. Using an extrahepatic cholestasis rat model by bile-duct ligation (BDL), daily oral administration of rosmarinic acid showed improvement effects on liver histology, serum biochemicals, ductular reaction, oxidative stress, inflammation, and fibrosis. Rosmarinic acid alleviated BDL-induced transforming growth factor beta-1 (TGF-β1) production and hepatic collagen deposition, and the anti-fibrotic effects were accompanied by reductions in matrix-producing cells and Smad2/3. BDL rats showed increased hepatic NF-κB/AP-1 activities, inflammatory cell infiltration/accumulation, and cytokine production, and these signs of hepatic inflammation were ameliorated by rosmarinic acid. Mechanistic study revealed an inhibitory effect of rosmarinic acid on the axis of the high mobility group box-1 (HMGB1)/toll-like receptor-4 (TLR4) in BDL rats. Results of cultured hepatic stellate cells further showed the impacts of rosmarinic acid which attenuated TGF-β1-induced stellate cell mitogenic and fibrogenic activation. Our findings support the concept that rosmarinic acid could serve as a hepatoprotective agent, and dietary rosmarinic acid supplementation may be beneficial in terms of improving cholestasis-related liver injury via mechanisms involving resolution of oxidative burden and down-regulation of HMGB1/TLR4, NF-κB, AP-1, and TGF-β1/Smad signaling.

Anti-fibrotic Effects of Synthetic Oligodeoxynucleotide for TGF-β1 and Smad in an Animal Model of Liver Cirrhosis

Liver fibrosis is characterized by changes in tissue architecture and extracellular matrix composition. Liver fibrosis affects not only hepatocytes but also the non-parenchymal cells such as hepatic stellate cells (HSCs), which are essential for maintaining an intact liver structure and function. Transforming growth factor β1 (TGF-β1) is a multifunctional cytokine that induces liver fibrosis through activation of Smad signaling pathways. To improve a new therapeutic approach, synthetic TGF-β1/Smad oligodeoxynucleotide (ODN) was used to suppress both TGF-β1 expression and Smad transcription factor using a combination of antisense ODN and decoy ODN. The aims of this study are to investigate the anti-fibrotic effects of TGF-β1/Smad ODN on simultaneous suppressions of both Smad transcription factor and TGF-β1 mRNA expression in the hepatic fibrosis model in vitro and in vivo. Synthetic TGF-β1/Smad ODN effectively inhibits Smad binding activity and TGF-β1 expression. TGF-β1/Smad ODN attenuated the epithelial mesenchymal transition (EMT) and activation of HSCs in TGF-β1-induced AML12 and HSC-T6 cells. TGF-β1/Smad ODN prevented the fibrogenesis and deposition of collagen in CCl₄-treated mouse model. Synthetic TGF-β1/Smad ODN demonstrates anti-fibrotic effects that are mediated by the suppression of fibrogenic protein and inflammatory cytokines. Therefore, synthetic TGF-β1/Smad ODN has substantial therapeutic feasibility for the treatment of liver fibrotic diseases.

Gremlin1 Accelerates Hepatic Stellate Cell Activation Through Upregulation of TGF-Beta Expression

Gremlin1, the antagonist of bone morphogenetic protein-7 and one of the target genes of transforming growth factor (TGF)-β signal pathway, plays an important role in embryonic development and its expression decreases along with aging. To explore the expression of gremlin1 in liver fibrosis and the causal link between gremlin1 and hepatic stellate cell (HSC) activation, we detected the expression of gremlin1 in mice with hepatic fibrosis induced by porcine serum using real time quantitative PCR (RT-qPCR) and immunohistochemical staining. The hepatic fibrosis mice were evaluated by the external feature of the liver, histology, hepatic function, collagen deposition, and the expression of fibrosis-related genes (genes COLIα2 and COLIVα2) in the liver. In the HSC-T6, western blotting was used to analyze the expression of α-smooth muscle actin (α-SMA), COL1α, and TGF-β1 in conditions of overexpression of gremlin1 or gremlin1 being knocked down by specific siRNA, respectively. The results showed that the mRNA expression of the gremlin1 gene was significantly increased consistent with increased expression of COLIα2 and COLIVα2 in the liver tissue of the hepatic fibrosis mice. Increased expression of gremlin1 coincided with the same area of the collagen deposition. Furthermore, the results also showed that the expression of α-SMA, COLIα1, and TGF-β1 was consistent with the expression of gremlin1 not only in the HSC-T6 overexpressing gremlin1 but also in the HSC-T6 that gremlin1 is knocked down by specific siRNA. The findings suggest that gremlin1 might play an important role in the progression of hepatic fibrosis and that it modulates HSC activation.

The stellate cell system (vitamin A-storing cell system)

Past, present, and future research into hepatic stellate cells (HSCs, also called vitamin A-storing cells, lipocytes, interstitial cells, fat-storing cells, or Ito cells) are summarized and discussed in this review. Kupffer discovered black-stained cells in the liver using the gold chloride method and named them stellate cells (Sternzellen in German) in 1876. Wake rediscovered the cells in 1971 using the same gold chloride method and various modern histological techniques including electron microscopy. Between their discovery and rediscovery, HSCs disappeared from the research history. Their identification, the establishment of cell isolation and culture methods, and the development of cellular and molecular biological techniques promoted HSC research after their rediscovery. In mammals, HSCs exist in the space between liver parenchymal cells (PCs) or hepatocytes and liver sinusoidal endothelial cells (LSECs) of the hepatic lobule, and store 50-80% of all vitamin A in the body as retinyl ester in lipid droplets in the cytoplasm. SCs also exist in extrahepatic organs such as pancreas, lung, and kidney. Hepatic (HSCs) and extrahepatic stellate cells (EHSCs) form the stellate cell (SC) system or SC family; the main storage site of vitamin A in the body is HSCs in the liver. In pathological conditions such as liver fibrosis, HSCs lose vitamin A, and synthesize a large amount of extracellular matrix (ECM) components including collagen, proteoglycan, glycosaminoglycan, and adhesive glycoproteins. The morphology of these cells also changes from the star-shaped HSCs to that of fibroblasts or myofibroblasts.

Smad2 increases the apoptosis of activated human hepatic stellate cells induced by TRAIL

The activation of hepatic stellate cells (HSCs) plays a critical role in the development of liver fibrosis. The induction of apoptosis in activated HSCs during the recovery phase of hepatic fibrosis represents a potential anti-fibrotic therapy. We have previously shown that Smad2 protects against hepatic fibrogenesis; however, the role of Smad2 in the regulation of activated HSC apoptosis remains unknown. We hypothesized that Smad2 regulates the apoptosis of activated HSCs, leading to the resolution of liver fibrosis. To test this hypothesis, the livers of rats were harvested at 0 and 4 weeks after hepatic fibrosis was established by CCl4 injection. Furthermore, TGF-β1-activated HSCs were treated with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) following the silencing or overexpression of Smad2. Both the phosphorylation of Smad2 and TRAIL were detected in fibrotic liver tissues. The results of TUNEL and α-SMA double-staining showed an increase in the apoptosis of activated HSCs during the spontaneous recovery phase. The knockdown of Smad2 reduced TRAIL-induced apoptosis in TGF-β1-activated human LX-2 cells and resulted in an increased expression of α-SMA and collagen I (Col. I). In contrast, the overexpression of Smad2 increased TRAIL-induced HSC apoptosis and reduced the expression of α-SMA and Col. I. The mechanisms underlying these findings were associated with the Smad2-mediated down-regulation of X-linked inhibitor of apoptosis protein (XIAP), resulting in enhanced caspase-3 activity and apoptosis. In conclusion, Smad2 enhances TRAIL-induced apoptosis in activated HSCs, which facilitates the resolution of hepatic fibrosis.

Fibroblast growth factor 21 attenuates hepatic fibrogenesis through TGF-β/smad2/3 and NF-κB signaling pathways

Fibroblast growth factor 21 (FGF-21) is a secreted protein, which has anti-diabetic and lipocaic effects, but its ability to protect against hepatic fibrosis has not been studied. In this study, we investigated the ability of FGF-21 to attenuate dimethylnitrosamine (DMN)-induced hepatic fibrogenesis in mice and the mechanism of its action. Hepatic fibrosis was induced by injection of DMN, FGF-21 was administered to the mice once daily in association with DMN injection till the end of the experiment. Histopathological examination, tissue 4-hydroxyproline content and expressions of smooth muscle α-actin (α-SMA) and collagen I were measured to assess hepatic fibrosis. Ethanol/PDGF-BB-activated hepatic stellate cells (HSCs) were used to understand the mechanisms of FGF-21 inhibited hepatic fibrogenesis. Results showed that FGF-21 treatment attenuated hepatic fibrogenesis and was associated with a significant decrease in intrahepatic fibrogenesis, 4-hydroxyproline accumulation, α-SMA expression and collagen I deposition. FGF-21 treatment inhibited the activation of HSCs via down-regulating the expression of TGF-β, NF-κB nuclear translocation, phosphorylation levels of smad2/3 and IκBα. Besides, FGF-21 treatment caused activated HSC apoptosis with increasing expression of Caspase-3, and decreased the ratio of Bcl-2 to Bax. In conclusion, FGF-21 attenuates hepatic fibrogenesis and inhibits the activation of HSC warranting the use of FGF-21 as a potential therapeutic agent in the treatment of hepatic fibrosis.

Role of Bone Marrow Mesenchymal Stem Cells in the Treatment of CCL4 Induced Liver Fibrosis in Albino Rats: A Histological and Immunohistochemical Study

BACKGROUND AND OBJECTIVES

Variety of pathological factors including viral hepatitis, alcohol and drug abuse, metabolic diseases, autoimmune diseases and congenital abnormalities can cause hepatic injury. Liver transplantation is the treatment of choice for end-stage liver diseases, however, it faces several difficulties. So the aim of the work is to evaluate the effect of bone marrow derived mesenchymal stem cells (BM-MSCs) on the liver structure in carbon tetra chloride CCL4 induced liver fibrosis in rats.

MATERIALS AND RESULTS

BM-MSCs were isolated and characterized from long bones of twenty male albino rats. Sixty female rats were divided into the following two groups: Group I; thirty rats which were the control group. Group II; thirty rats were injected intra-peritoneal (IP) by CCL4 twice weekly for four weeks and was further subdivided into the following three subgroups: Subgroup IIA (CCL4 alone); included ten rats which were sacrificed after this four weeks. Subgroup IIB (CCL4/MSCs); included ten rats which were IP injected by a single dose of BM-MSCs and were sacrificed after four weeks. Subgroup IIC (CCL4/recovery); included ten rats which were left for another four weeks without any intervention. Histological examination of liver specimens showed that CCl4 caused variable pathological changes with elevated liver enzymes. Injection of BM-MSCs revealed an improvement in the histological picture of the liver and its enzymatic profile. On the other hand, most of the pathological lesion were still detected in rats of recovery group.

CONCLUSIONS

BM-MSC could restore the liver structure and function in experimental model of liver fibrosis.

Beneficial effect of quercetin on cholestatic liver injury

Bile duct obstruction and subsequent cholestasis are associated with hepatocellular injury, cholangiocyte proliferation, stellate cell activation, Kupffer cell activation, oxidative stress, inflammation and fibrosis. Flavonoids have been shown to confer beneficial health effects, including hepatoprotection. However, the molecular mechanism of flavonoid-mediated hepatoprotection is incompletely understood. In this study, we report the protective effect of quercetin on cholestatic liver injury. Cholestasis was produced by bile duct ligation (BDL) in male Sprague-Dawley rats for 3 weeks. Daily oral administration of quercetin was started 1 week before injury and lasted for 4 weeks. In comparison with the control group, the BDL group showed liver injury, as evidenced by histological changes, and elevation in serum biochemicals, ductular reaction, fibrosis, inflammation and oxidative stress. These pathophysiological changes were attenuated by daily quercetin supplementation. Quercetin alleviated BDL-induced transforming growth factor beta-1 (TGF-β1), interleukin-1 beta, connective tissue growth factor and collagen expression. The antifibrotic effect of quercetin was accompanied by reductions in α-smooth muscle actin-positive matrix-producing cells and Smad 2/3 activity critical to the fibrogenic potential of TGF-β1. Quercetin also attenuated BDL-induced oxidative stress, leukocyte accumulation, nuclear factor (NF)-κB activation and proinflammatory cytokine production. Further studies demonstrated an inhibitory effect of quercetin on MyD88 and TGF-β-activated kinase-1 critical for linking toll-like receptor (TLR) and NF-κB. Taken together, the hepatoprotective, anti-inflammatory and antifibrotic effects of quercetin seem to be multifactorial. The beneficial effects of daily quercetin supplementation are associated with antioxidative and anti-inflammatory potential as well as down-regulation of NF-κB and TGF-β/Smad signaling, probably via interference with TLR signaling.

Pin1 induction in the fibrotic liver and its roles in TGF-β1 expression and Smad2/3 phosphorylation

BACKGROUND & AIMS

Therapeutic management of liver fibrosis remains an unsolved clinical problem. Hepatic accumulation of extracellular matrix, mainly collagen, is mediated by the production of transforming growth factor-β1 (TGF-β1) in stellate cells. Pin1, a peptidyl-prolyl isomerase, plays an important pathophysiological role in several diseases, including neurodegeneration and cancer. Herein, we determined whether Pin1 regulates liver fibrogenesis and examined its mechanism of action by focusing on TGF-β1 signalling and hepatic stellate cell (HSC) activation.

METHODS

Pin1 expression was assessed by immunohistochemistry, Western blot or real-time-polymerase chain reaction (RT-PCR) analyses of human and mouse fibrotic liver samples. The role of Pin1 during HSC activation was estimated using Pin1-null mouse embryonic fibroblast (MEF) cells and Pin1-overexpressing LX-2 human hepatic stellate cells.

RESULTS

Pin1 expression was elevated in human and mouse fibrotic liver tissues, and Pin1 inhibition improved dimethylnitrosamine (DMN)-induced liver fibrosis in mice. Pin1 inhibition reduced the mRNA or protein expression of TGF-β1 and α-smooth muscle actin (α-SMA) by DMN treatment. Pin1 knockdown suppressed TGFβ1 gene expression in both LX-2 and MEF cells. Pin1-mediated TGFβ1 gene transcription was controlled by extracellular signal-regulated kinase (ERK)- and phosphoinositide 3-kinase/Akt-mediated activator protein-1 (AP-1) activation. Moreover, TGFβ1-stimulated Smad2/3 phosphorylation and plasminogen activator inhibitor-1 expression were inhibited by Pin1 knockdown.

CONCLUSIONS

Pin1 induction during liver fibrosis is involved in hepatic stellate cell activation, TGFβ1 expression, and TGFβ1-mediated fibrogenesis signalling.

Combined taurine, epigallocatechin gallate and genistein therapy reduces HSC-T6 cell proliferation and modulates the expression of fibrogenic factors

Hepatic fibrogenesis involves the activation of hepatic stellate cells (HSCs), which synthesize excess extracellular matrix and contribute to the development of liver fibrosis. In a prior study we tested the effect of combined treatment with taurine, epigallocatechin gallate and genistein on the development of alcohol-induced liver fibrosis in vitro. In this study, the biological activity of the combination of these molecules was assessed by measuring its effect on cell proliferation, fibrosis-related gene expression, and proteomic expression profiling in the activated HSC cell line, HSC-T6. HSC-T6 cells were incubated with different concentrations of the drug combination taurine, epigallocatechin gallate and genistein. Cell proliferation was evaluated by MTT assay. Transforming growth factor β1 (TGF-β1), collagen type I (Col-I), matrix metalloproteinase-2 (MMP-2), and tissue inhibitor of metalloproteinases 1 and 2 (TIMP-1 and TIMP-2) mRNA were analyzed by semi-quantitative reverse-transcription PCR. Proteomic profiling of HSC-T6 cells was also performed by SELDI-TOF-MS. Combined drug treatment significantly inhibited cell proliferation and TGF-β1, Col-I, TIMP-1 and TIMP-2 mRNA expression in activated HSC-T6 cells, while the expression of MMP-2 mRNA increased. A total of 176 protein m/z peaks were identified. The intensities of 10 protein peaks were downregulated and two protein peaks were upregulated in HSC-T6 cells after combined drug treatment. In conclusion, combined drug treatment with taurine, epigallocatechin gallate and genistein can inhibit HSC proliferation, and impact fibrosis-related gene and protein expression. The antifibrotic effects of this drug combination may be due to its effects on the expression of fibrogenic genes.

Alleviation of Dimethylnitrosamine-Induced Liver Injury and Fibrosis by Supplementation of Anabasis articulata Extract in Rats

Anabasis articulata (Forssk) Moq. (Chenopodiaceae) is an herb, grows in Egypt, and used in folk medicine to treat diabetes, fever, and kidney infections. The protective and therapeutic effects of the ethanol extract of A. articulata aerial parts were evaluated against dimethylnitrosamine (DMN)-induced liver fibrosis, compared with the standard drug, silymarin. Hepatic hydroxyproline content, serum transforming growth factor-β1 (TGF-β1), interleukin 10 (IL-10) and fructosamine were measured as liver fibrosis markers. Hepatic malondialdehyde (MDA), nitric oxide (NO), catalase (CAT), glutathione reductase (GR) and glutathione content (GSH) were measured as oxidant/antioxidant markers. Parallel histopathological investigations were also performed. Protective and therapeutic administration of A. articulata (100 mg/kg daily for 4 weeks), markedly prevented DMN-induced loss in body and liver weights. The extract significantly inhibited the elevation of hepatic hydroxyproline, NO and MDA (P < 0.05), as well as serum fructosamine, and TGF-β1 (P < 0.05) induced by DMN while it restored IL-10 to normal level in both protective and therapeutic groups. Furthermore, A. articulata prevented the depletion in CAT, GR, and GSH levels (P ≤ 0.05). In addition, oral administration of A. articulata extract and silymarin to both protective and therapeutic groups reduced the increase in liver function enzyme activities; alanine and aspartate amintransferases, gamma-glutamyl transferase in addition to alkaline phosphatase, and caused significant increase in serum albumin concentration as compared to DMN group. These data corresponded closely with those obtained for the drug silymarin. Histopathological studies confirmed the biochemical data and revealed remarkable improvement in liver architecture. Thus, it could be concluded that, A. articulata extract exhibited in vivo hepatoprotective and therapeutic effects against DMN-induced liver injury and may act as a useful agent in controlling the progression of hepatic fibrosis through reduction of oxidative stress and improving liver function.

MicroRNA-29 family, a crucial therapeutic target for fibrosis diseases

MicroRNAs (miRNAs) are a class of approximately 20-nucleotides single-stranded endogenous RNAs that regulate gene expression at the post-transcriptional level. miRNAs have recently been known to regulate cell proliferation, differentiation, and apoptosis. Fibrosis is the leading cause of organ dysfunction in diseases and results from an imbalance in the turnover of extracellular matrix components. Accumulating studies have demonstrated that miR-29 family participates in the development of liver fibrosis, renal fibrosis, pulmonary fibrosis, cardiac fibrosis. In this review, we are discussing the comprehensive role of miR-29 family in moderating profibrotic effect and its potential as therapeutic approach to fibrosis diseases.

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.

Activation of TGF-β1 promoter by hepatitis C virus-induced AP-1 and Sp1: role of TGF-β1 in hepatic stellate cell activation and invasion

Our previous studies have shown the induction and maturation of transforming growth factor-beta 1 (TGF-β1) in HCV-infected human hepatoma cells. In this study, we have investigated the molecular mechanism of TGF-β1 gene expression in response to HCV infection. We demonstrate that HCV-induced transcription factors AP-1, Sp1, NF-κB and STAT-3 are involved in TGF-β1 gene expression. Using chromatin immunoprecipitation (ChIP) assay, we further show that AP-1 and Sp1 interact with TGF-b1 promoter in vivo in HCV-infected cells. In addition, we demonstrate that HCV-induced TGF-β1 gene expression is mediated by the activation of cellular kinases such as p38 MAPK, Src, JNK, and MEK1/2. Next, we determined the role of secreted bioactive TGF-β1 in human hepatic stellate cells (HSCs) activation and invasion. Using siRNA approach, we show that HCV-induced bioactive TGF-β1 is critical for the induction of alpha smooth muscle actin (α-SMA) and type 1 collagen, the markers of HSCs activation and proliferation. We further demonstrate the potential role of HCV-induced bioactive TGF-β1 in HSCs invasion/cell migration using a transwell Boyden chamber. Our results also suggest the role of HCV-induced TGF-β1 in HCV replication and release. Collectively, these observations provide insight into the mechanism of TGF-β1 promoter activation, as well as HSCs activation and invasion, which likely manifests in liver fibrosis associated with HCV infection.

Protective Effects of Guava Pulp on Cholestatic Liver Injury

Background. Cholestatic liver injury is a leading cause of chronic liver diseases involved with oxidative stress changes and inflammation; thus, antioxidant and anti-inflammation compound-rich guava may play a pivotal role in protecting against the cholestatic liver damages. Our aims for this study are to determine whether guava pulp (GP) has protective effects on cholestatic liver injury-induced mouse model and on interleukin-6 (IL-6) mediated proliferation of QBC939 cholangiocarcinoma cell line. Methods. Mice were induced to cholestatic liver damage by left and median bile duct ligation (LMBDL) surgery and then treated with GP. Plasma and liver samples were collected for biochemical and pathological assays. 5-Bromo-2'-deoxyuridine (BrdU) assay and Western blots were used to detect proliferation and gene expression in QBC939 cells, respectively. Results. Compared with LMBDL only group, in GP-treated mice, the levels of alanine aminotransferase (ALT) and bilirubin decreased, biliary epithelial cell proliferation and liver fibrogenesis were suppressed, Src/MEK/ERK1/2/c-Myc pathway and expressions of transforming growth factor β1(TGF-β1), tissue inhibitor of metalloproteinases TIMP), and procollagen 1α1(COL1α1) were downregulated significantly. Moreover, the GP extract reduced IL-6-enhanced QBC939 cell proliferation, p-ERK, and c-Myc expression as well. Conclusions. GP may provide a new perspective for the treatment of cholestatic liver injury.

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.

Withaferin-A reduces type I collagen expression in vitro and inhibits development of myocardial fibrosis in vivo

Type I collagen is the most abundant protein in the human body. Its excessive synthesis results in fibrosis of various organs. Fibrosis is a major medical problem without an existing cure. Excessive synthesis of type I collagen in fibrosis is primarily due to stabilization of collagen mRNAs. We recently reported that intermediate filaments composed of vimentin regulate collagen synthesis by stabilizing collagen mRNAs. Vimentin is a primary target of Withaferin-A (WF-A). Therefore, we hypothesized that WF-A may reduce type I collagen production by disrupting vimentin filaments and decreasing the stability of collagen mRNAs. This study is to determine if WF-A exhibits anti-fibrotic properties in vitro and in vivo and to elucidate the molecular mechanisms of its action. In lung, skin and heart fibroblasts WF-A disrupted vimentin filaments at concentrations of 0.5-1.5 µM and reduced 3 fold the half-lives of collagen α1(I) and α2(I) mRNAs and protein expression. In addition, WF-A inhibited TGF-β1 induced phosphorylation of TGF-β1 receptor I, Smad3 phosphorylation and transcription of collagen genes. WF-A also inhibited in vitro activation of primary hepatic stellate cells and decreased their type I collagen expression. In mice, administration of 4 mg/kg WF-A daily for 2 weeks reduced isoproterenol-induced myocardial fibrosis by 50%. Our findings provide strong evidence that Withaferin-A could act as an anti-fibrotic compound against fibroproliferative diseases, including, but not limited to, cardiac interstitial fibrosis.

The potential of microRNAs in liver fibrosis

MicroRNAs (miRNAs) are a class of ~22-nucleotides noncoding RNAs that regulate gene expression by specifically binding with 3'-untranslated region (3'-UTR) of target gene mRNAs to posttranscriptionally effect mRNA stability and translation,and play essential roles in a variety of biological processes, including cell development, proliferation, differentiation, and apoptosis. Liver fibrosis is the occurrence of liver cell necrosis and inflammatory stimulation, and is characterized by excessive accumulation of extracellular matrices(ECMs). In the fibrotic liver, hepatic stellate cells (HSCs), which are regulated by multiple signal transduction pathways, undergo myofibroblastic transdifferentiation and are generally regarded as the major ECM producer responsible for liver fibrosis. A growing body of evidence suggests that divergent miRNAs participate in liver fibrotic process and activation of HSC. Moreover, members of many signal transduction pathways are important targets for miRNAs. In this review, we make a summary on current understanding of the roles of miRNAs in the development of liver fibrosis, HSC functions and their potential as novel drug targets.

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.

MicroRNA-146a modulates TGF-beta1-induced hepatic stellate cell proliferation by targeting SMAD4

Activation of hepatic stellate cells (HSC) plays a pivotal role in the development of hepatic fibrosis. Transforming growth factor-β1 (TGF-β1) is considered to be the main stimuli factor responsible for the activation of HSC. MicroRNAs (miRNAs) have recently been shown to regulate cell proliferation, differentiation, and apoptosis. The involvement of miRNAs and their roles in TGF-β1-induced HSC activation remains largely unknown. Our study found that the expression of miR-146a was downregulated in HSC in response to TGF-β1 stimulation in dose-dependent manner by one-step real-time quantitative PCR. Moreover, we sought to examine whether miR-146a became dysregulated in CCl(4)-induced hepatic fibrosis in rats. Our study revealed that miR-146a was downregulated in liver fibrotic tissues. In addition, The HSC transfected with miR-146a mimics exhibited attendated TGF-β1-induced α-smooth muscle actin (α-SMA) expression compared with the control. Furthermore, overexpression of miR-146a suppressed TGF-β-induced HSC proliferation, and increased HSC apoptosis. Bioinformatics analyses predict that SMAD4 is the potential target of miR-146a. MiR-146a overexpression in TGF-β1-treated HSC did not decrease target mRNA levels, but significantly reduced target protein expression. These results suggested that miR-146a may function as a novel regulator to modulate HSC activation during TGF-β1 induction by targeting SMAD4.

Targeted TFO delivery to hepatic stellate cells

Triplex-forming oligonucleotides (TFOs) represent an antigene approach for gene regulation through direct interaction with genomic DNA. While this strategy holds great promise owing to the fact that only two alleles need silencing to impact gene regulation, delivering TFOs to target cells in vivo is still a challenge. Our recent efforts have focused on conjugating TFOs to carrier molecules like cholesterol to enhance their cellular uptake and mannose-6-phosphate-bovine serum albumin (M6P-BSA) to target TFO delivery to hepatic stellate cells (HSCs) for treating liver fibrosis. These approaches however are rendered less effective owing to a lack of targeted delivery, as seen with lipid-conjugates, and the potential immune reactions due to repeated dosing with high molecular weight BSA conjugated TFO. In this review, we discuss our latest efforts to enhance the effectiveness of TFO for treating liver fibrosis. We have shown that conjugation of TFOs to M6P-HPMA can enhance TFO delivery to HSCs and has the potential to treat liver fibrosis by inhibiting collagen synthesis. This TFO conjugate shows negligible immunogenicity owing to the use of HPMA, one of the least immunogenic copolymers, thereby making it a suitable and more effective candidate for antifibrotic therapy.

The antifibrotic effects of TGF-β1 siRNA on hepatic fibrosis in rats

BACKGROUND/AIMS

Hepatic fibrosis results from the excessive secretion of matrix proteins by hepatic stellate cells (HSCs), which proliferate during fibrotic liver injury. Transforming growth factor (TGF)-β1 is the dominant stimulus for extracellular matrix (ECM) production by stellate cells. Our study was designed to investigate the antifibrotic effects of using short interference RNA (siRNA) to target TGF-β1 in hepatic fibrosis and its mechanism in rats exposed to a high-fat diet and carbon tetrachloride (CCL4).

METHODS

A total of 40 healthy, male SD (Sprague-Dawley) rats were randomly divided into five even groups containing of eight rats each: normal group, model group, TGF-β1 siRNA 0.125mg/kg treatment group, TGF-β1 siRNA 0.25mg/kg treatment group and TGF-β1 siRNA negative control group (0.25mg/kg). CCL4 and a high-fat diet were used for 8weeks to induce hepatic fibrosis. All the rats were then sacrificed to collect liver tissue samples. A portion of the liver samples were soaked in formalin for Hematoxylin-Eosin staining, classifying the degree of liver fibrosis, and detecting the expression of type I and III collagen and TGF-β1; the remaining liver samples were stored in liquid nitrogen to be used for detecting TGF-β1 by Western blotting and for measuring the mRNA expression of type I and III collagen and TGF-β1 by quantitative real-time polymerase chain reaction.

RESULTS

Comparing the TGF-β1 siRNA 0.25mg/kg treatment group to the model group, the TGF-β1 siRNA negative control group and the TGF-β1 siRNA 0.125 mg/kg treatment group showed significantly reduced levels of pathological changes, protein expression and the mRNA expression of TGF-β1, type I collagen and type III collagen (P<0.01).

CONCLUSIONS

Using siRNA to target TGF-β1 can inhibit the expression of TGF-β1 and attenuate rat hepatic fibrosis induced by a high-fat diet and CCL4. A possible mechanism is through the down-regulation of TGF-β1 expression, which could inhibit HSC activation, as well as the proliferation and collagen production of collagen reducing, so that collagen deposition in the liver is reduced.

Beneficial effect of docosahexaenoic acid on cholestatic liver injury in rats

Bile duct obstruction and subsequent cholestasis are associated with hepatocellular injury, cholangiocyte proliferation, stellate cell activation, Kupffer cell activation, oxidative stress, inflammation and fibrosis. Docosahexaenoic acid (DHA) is an essential polyunsaturated fatty acid that has been shown to possess health beneficial effects, including hepatoprotection. However, the molecular mechanism of DHA-mediated hepatoprotection is not fully understood. In the present study, we report the protective effect of DHA on cholestatic liver injury. Cholestasis was produced by bile duct ligation (BDL) in male Sprague-Dawley rats for 3 weeks. Daily administration of DHA was started 2 weeks before injury and lasted for 5 weeks. In comparison with the control group, the BDL group showed hepatic damage as evidenced by histological changes and elevation in serum biochemicals, ductular reaction, fibrosis, inflammation and oxidative stress. These pathophysiological changes were attenuated by chronic DHA supplementation. DHA alleviated BDL-induced transforming growth factor beta-1 (TGF-β1), intereukin-1beta, connective tissue growth factor and collagen expression. The anti-fibrotic effect of DHA was accompanied by reductions in α-smooth muscle actin-positive matrix-producing cells and Smad 2/3 activity critical to the fibrogenic potential of TGF-β1. DHA also attenuated BDL-induced leukocyte accumulation and nuclear factor-κB (NF-κB) activation. Further studies demonstrated an inhibitory effect of DHA on redox-sensitive intracellular signaling molecule extracellular signal-regulated kinase (ERK). Taken together, the hepatoprotective, anti-inflammatory and anti-fibrotic effects of DHA seem to be multifactorial. The beneficial effects of chronic DHA supplementation are associated with anti-oxidative and anti-inflammatory potential as well as down-regulation of NF-κB and transforming growth factor beta/Smad signaling probably via interference with ERK activation.

Effects of p-CREB-1 on transforming growth factor-β3 auto-regulation in hepatic stellate cells

Previous studies have demonstrated that transforming growth factor-β3 (TGF-β3) protected liver against fibrosis in vivo and vitro, but its regulation is poorly understood. In addition, the cAMP-responsive element (CRE) in TGF-β3 promoter is recognized as an important regulatory site for TGF-β3 auto-regulation. Thus, we hypothesize that transcription factor CRE-binding protein-1 (CREB-1) regulates the auto-induction of TGF-β3 in hepatic stellate cells (HSCs). We used exogenous TGF-β3 to activate the signal pathway of TGF-β3 auto-regulation in HSCs, results indicated that exogenous TGF-β3 could up-regulate the protein and mRNA expressions of TGF-β3, and provoke the phosphorylation of CREB-1 on Ser-133, besides, it could induce the DNA binding activity of p-CREB-1 and activate TGF-β3 promoter as well. Additionally, we used pGenesil-1.1-shRNA-CREB-1 and pRSV-CREB-1 expression vector to silence and up-regulate CREB-1 gene expression respectively, and the results indicated that inhibition of CREB-1 suppressed exogenous TGF-β3 stimulation of TGF-β3 mRNA and protein expressions in HSCs, whereas up-regulation of CREB-1 induced this stimulation. Our results indicate that exogenous TGF-β3 up-regulates the activity of TGF-β3 promoter by activating CREB-1, then induces the mRNA and protein expressions of TGF-β3. Especially, p-CREB-1 is a critical transcription factor in mediating TGF-β3 auto-induction.

Targeting transforming growth factor βRII expression inhibits the activation of hepatic stellate cells and reduces collagen synthesis

Abnormal production of extracellular matrix (ECM) components significantly contributes to the development of liver fibrosis. This study aimed at examining the effects of short-hairpin RNA (shRNA)-mediated transient knockdown of transforming growth factor βRII (TGFβRII) expression on the proliferation and activation of hepatic stellate cells (HSCs) and synthesis of fibrogenic ECM components in HSC cells. Three different shRNA-expressing plasmids were constructed for the expression of shRNA-(a, b, c) targeting to the rat TGFβRII mRNA beginning at nucleotide position 339, 444 and 528 and they were transfected into a rat stellate cell line, HSC-T6 cells, respectively. The levels of TGFβRII, α-smooth muscle actin (α-SMA), and type I and III collagen expressions were characterized by reverse transcription polymerase chain reaction and Western blot assays. The concentrations of hyaluronic acid (HA) and type IV collagen in the supernatants of cultured cells were measured by enzyme-linked immunosorbent assay. Transfection with the TGFβRII-specific shRNAs resulted in varying levels of inhibition in the expression of TGFβRII in HSC-T6 cells, and transfection with the potent shRNA-c inhibited the expression of TGFβRII in a dose-dependent manner. Knockdown of TGFβRII expression significantly reduced the levels of α-SMA, type I, III and IV collagen, and HA expression in HSC-T6 cells (P < 0.01). In conclusion, our data indicated that knockdown of TGFβRII expression inhibited the activation of HSCs and the production of fibrogenic ECM components in HSC-T6 cells. Therefore, our findings support the notion that TGFβRII is an important factor of the pathogenic process of liver fibrosis.

Hepatic stellate cell (vitamin A-storing cell) and its relative--past, present and future

HSCs (hepatic stellate cells) (also called vitamin A-storing cells, lipocytes, interstitial cells, fat-storing cells or Ito cells) exist in the space between parenchymal cells and liver sinusoidal endothelial cells of the hepatic lobule and store 50-80% of vitamin A in the whole body as retinyl palmitate in lipid droplets in the cytoplasm. In physiological conditions, these cells play pivotal roles in the regulation of vitamin A homoeostasis. In pathological conditions, such as hepatic fibrosis or liver cirrhosis, HSCs lose vitamin A and synthesize a large amount of extracellular matrix components including collagen, proteoglycan, glycosaminoglycan and adhesive glycoproteins. Morphology of these cells also changes from the star-shaped SCs (stellate cells) to that of fibroblasts or myofibroblasts. The hepatic SCs are now considered to be targets of therapy of hepatic fibrosis or liver cirrhosis. HSCs are activated by adhering to the parenchymal cells and lose stored vitamin A during hepatic regeneration. Vitamin A-storing cells exist in extrahepatic organs such as the pancreas, lungs, kidneys and intestines. Vitamin A-storing cells in the liver and extrahepatic organs form a cellular system. The research of the vitamin A-storing cells has developed and expanded vigorously. The past, present and future of the research of the vitamin A-storing cells (SCs) will be summarized and discussed in this review.

Targeted delivery of siRNA to hepatocytes and hepatic stellate cells by bioconjugation

Previously, we successfully conjugated galactosylated poly(ethylene glycol) (Gal-PEG) to oligonucleotides (ODNs) via an acid labile ester linker (Zhu et al., Bioconjugate Chem. 2008, 19, 290-8). In this study, sense strands of siRNA were conjugated to Gal-PEG and mannose 6-phosphate poly(ethylene glycol) (M6P-PEG) for targeted delivery of siRNAs to hepatocytes and hepatic stellate cells (HSCs), respectively. These siRNA conjugates were purified by ion exchange chromatography and verified by gel retardation assay. To evaluate their RNAi functions, the validated siRNA duplexes targeting firefly luciferase and transforming growth factor beta 1 (TGF-β1) mRNA were conjugated to Gal-PEG and M6P-PEG, and their gene silencing efficiencies were determined after transfection into HepG2 and HSC-T6 cells. The disulfide bond between PEG and siRNA was cleaved by dithiothreitol, leading to the release of intact siRNA. Both Gal-PEG-siRNA and M6P-PEG-siRNA conjugates could silence luciferase gene expression by about 40% without any transfection reagents, while the gene silencing effects reached more than 98% with the help of cationic liposomes at the same dose. Conjugation of TGF-β1 siRNA with Gal-PEG and M6P-PEG could silence endogenous TGF-β1 gene expression as well. In conclusion, these siRNA conjugates have the potential for targeted delivery of siRNAs to hepatocytes and hepatic stellate cells for efficient gene silencing in vivo.

Inhibition of liver fibrosis by solubilized coenzyme Q10: Role of Nrf2 activation in inhibiting transforming growth factor-beta1 expression

Coenzyme Q10 (CoQ10), an endogenous antioxidant, is important in oxidative phosphorylation in mitochondria. It has anti-diabetic and anti-cardiovascular disease effects, but its ability to protect against liver fibrosis has not been studied. Here, we assessed the ability of solubilized CoQ10 to improve dimethylnitrosamine (DMN)-induced liver fibrogenesis in mice. DMN treatments for 3 weeks produced a marked liver fibrosis as assessed by histopathological examination and tissue 4-hydroxyproline content. Solubilized CoQ10 (10 and 30 mg/kg) significantly inhibited both the increases in fibrosis score and 4-hydroxyproline content induced by DMN. Reverse transcription-polymerase chain reaction and Western blot analyses revealed that solubilized CoQ10 inhibited increases in the transforming growth factor-beta1 (TGF-beta1) mRNA and alpha-smooth muscle actin (alpha-SMA) protein by DMN. Interestingly, hepatic glutamate-cysteine ligase (GCL) and glutathione S-transferase A2 (GSTA2) were up-regulated in mice treated with CoQ10. Solubilized CoQ10 also up-regulated antioxidant enzymes such as catalytic subunits of GCL and GSTA2 via activating NF-E2 related factor2 (Nrf2)/antioxidant response element (ARE) in H4IIE hepatoma cells. Moreover, CoQ10's inhibition of alpha-SMA and TGF-beta1 expressions disappeared in Nrf2-null MEF cells. In contrast, Nrf2 overexpression significantly decreased the basal expression levels of alpha-SMA and TGF-beta1 in Nrf2-null MEF cells. These results demonstrated that solubilized CoQ10 inhibited DMN-induced liver fibrosis through suppression of TGF-beta1 expression via Nrf2/ARE activation.

TGF-beta1 gene silencing for treating liver fibrosis

Small interfering RNA (siRNA) and short hairpin RNA (shRNA) targeting different regions of transforming growth factor beta1 (TGF-beta1) mRNA were designed and the silencing effect was determined after transfection into immortalized rat liver stellate cells (HSC-T6). There was not only significant decrease in TGF-beta1, tissue inhibitor of metalloproteinase 1 (TIMP-1), alpha-smooth muscle actin (alpha-SMA) and type I collagen after transfection with TGF-beta1 siRNAs, but also synergism in gene silencing when siRNAs targeting two different start sites were used as a pool for transfection. The two siRNA sequences which efficiently inhibited TGF-beta1 gene expression were converted to shRNAs via cloning into the pSilencer1.0. There was significant decrease in TGF-beta1 and TIMP-1 when HSC-T6 cells were transfected with pshRNA targeting the same regions of TGF-beta1 mRNA as siRNAs. Furthermore, TGF-beta1 gene silencing in HSC-T6 cells significantly decreased the levels of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1beta). In conclusion, both siRNA and shRNA showed sequence-specific and dose dependent TGF-beta1 gene silencing and have the potential to treat liver fibrosis.

Protective effect of morin on dimethylnitrosamine-induced hepatic fibrosis in rats

Morin, a plant-derived flavonoid, has been reported to exhibit a wide range of pharmacological properties. In this study, we investigated the protective effect of morin on hepatic fibrosis induced by dimethylnitrosamine (DMN) in rats. Oral administration of morin remarkably prevented weight loss in the body and liver from DMN and inhibited the elevation of serum alanine transaminase (ALT), aspartate transaminase (AST), and total bilirubin levels. For the evaluation of hepatic fibrosis-related factors, we investigated expressions of collagen type I, transforming growth factor beta(1) (TGF-beta(1)), and alpha-smooth muscle actin (alpha-SMA) in mRNA and protein levels. We observed that morin significantly reduced the expression of collagen type I, TGF-beta(1), and alpha-SMA on hepatic fibrosis induced by DMN. Taken together, this study demonstrated that morin showed hepatoprotective and antifibrogenic effects against DMN-induced hepatic injury. This suggests that morin may be useful in preventing the development of hepatic fibrosis and cirrhosis.

Fitting a xenobiotic receptor into cell homeostasis: how the dioxin receptor interacts with TGFbeta signaling

As our knowledge on the mechanisms that control cell function increases, more complex signaling pathways and quite intricate cross-talks among regulatory proteins are discovered. Establishing accurate interactions between cellular networks is essential for a healthy cell and different alterations in signaling are known to underline human disease. Transforming growth factor beta (TGFbeta) is an extracellular cytokine that regulates such critical cellular responses as proliferation, apoptosis, differentiation, angiogenesis and migration, and it is assumed that the latency-associated protein LTBP-1 plays a relevant role in TGFbeta targeting and activation in the extracellular matrix (ECM). The dioxin receptor (AhR) is a unique intracellular protein long studied because of its critical role in xenobiotic-induced toxicity and carcinogenesis. Yet, a large set of studies performed in cellular systems and in vivo animal models have suggested important xenobiotic-independent functions for AhR in cell proliferation, differentiation and migration and in tissue homeostasis. Remarkably, AhR activity converges with TGFbeta-dependent signaling through LTBP-1 since cells lacking AhR expression have phenotypic alterations that can be explained, at least in part, by the coordinated regulation of both proteins. Here, we will discuss the existence of functional interactions between AhR and TGFbeta signaling. We will focus on regulatory and functional aspects by analyzing how AhR status determines TGFbeta activity and by proposing a mechanism through which LTBP-1, a novel AhR target gene, mediates such effects. We will integrate ECM proteases in the AhR-LTBP-1-TGFbeta axis and suggest a model that could help explain some in vivo phenotypes associated to AhR deficiency.

Gene modulation for treating liver fibrosis

Despite tremendous progress in our understanding of fibrogenesis, injury stimuli process, inflammation, and hepatic stellate cell (HSC) activation, there is still no standard treatment for liver fibrosis. Delivery of small molecular weight drugs, proteins, and nucleic acids to specific liver cell types remains a challenge due to the overexpression of extracellular matrix (ECM) and consequent closure of sinusoidal gaps. In addition, activation of HSCs and subsequent release of inflammatory cytokines and infiltration of immune cells are other major obstacles to the treatment of liver fibrosis. To overcome these barriers, different therapeutic approaches are being investigated. Among them, the modulation of certain aberrant protein production is quite promising for treating liver fibrosis. In this review, we describe the mechanism of antisense, antigene, and RNA interference (RNAi) therapies and discuss how the backbone modification of oligonucleotides affects their in vivo stability, biodistribution, and bioactivity. Strategies for delivering these nucleic acids to specific cell types are discussed. This review critically addresses various insights developed with each individual strategy and for multipronged approaches, which will be helpful in achieving more effective outcomes.