Expression changes of activin A in the development of hepatic fibrosis

Pathological insights into activin A: Molecular underpinnings and therapeutic prospects in various diseases

Activin A (Act A) is a member of the TGFβ (transforming growth factor β) superfamily. It communicates via the Suppressor of Mothers against Decapentaplegic Homolog (SMAD2/3) proteins which govern processes such as cell proliferation, wound healing, apoptosis, and metabolism. Act A produces its action by attaching to activin receptor type IIA (ActRIIA) or activin receptor type IIB (ActRIIB). Increasing circulating Act A increases ActRII signalling, which on phosphorylation initiates the ALK4 (activin receptor-like kinase 4) type 1 receptor which further turns on the SMAD pathway and hinders cell functioning. Once triggered, this route leads to gene transcription, differentiation, apoptosis, and extracellular matrix (ECM) formation. Act A also governs the immunological and inflammatory responses of the body, as well as cell death. Moreover, Act A levels have been observed to elevate in several disorders like renal fibrosis, CKD, asthma, NAFLD, cardiovascular diseases, cancer, inflammatory conditions etc. Here, we provide an update on the recent studies relevant to the role of Act A in the modulation of various pathological disorders, giving an overview of the biology of Act A and its signalling pathways, and discuss the possibility of incorporating activin-A targeting as a novel therapeutic approach for the control of various disorders. Pathways such as SMAD signaling, in which SMAD moves to the nucleus by making a complex and leads to tissue fibrosis in CKD, STAT3, which drives renal fibroblast activity and the production of ECM, Kidney injury molecule (KIM-1) in the synthesis, deposition of ECM proteins, SERCA2a (sarcoplasmic reticulum Ca2+ ATPase) in cardiac dysfunction, and NF-κB (Nuclear factor kappa-light-chain-enhancer of activated B cells) in inflammation are involved in Act A signaling, have also been discussed.

Gastrointestinal pharmacology activins in liver health and disease

Activins are a subgroup of the TGFβ superfamily of growth and differentiation factors, dimeric in nature and consisting of two inhibin beta subunits linked via a disulfide bridge. Canonical activin signaling occurs through Smad2/3, with negative feedback initiated by Smad6/7 following signal transduction, which binds activin type I receptor preventing phosphorylation of Smad2/3 and activation of downstream signaling. In addition to Smad6/7, other inhibitors of activin signaling have been identified as well, including inhibins (dimers of an inhibin alpha and beta subunit), BAMBI, Cripto, follistatin, and follistatin-like 3 (fstl3). To date, activins A, B, AB, C, and E have been identified and isolated in mammals, with activin A and B having the most characterization of biological activity. Activin A has been implicated as a regulator of several important functions of liver biology, including hepatocyte proliferation and apoptosis, ECM production, and liver regeneration; the role of other subunits of activin in liver physiology are less understood. There is mounting data to suggest a link between dysregulation of activins contributing to various hepatic diseases such as inflammation, fibrosis, and hepatocellular carcinoma, and emerging studies demonstrating the protective and regenerative effects of inhibiting activins in mouse models of liver disease. Due to their importance in liver biology, activins demonstrate utility as a therapeutic target for the treatment of hepatic diseases such as cirrhosis, NASH, NAFLD, and HCC; further research regarding activins may provide diagnostic or therapeutic opportunity for those suffering from various liver diseases.

Inflammatory processes in the liver: divergent roles in homeostasis and pathology

The hepatic immune system is designed to tolerate diverse harmless foreign moieties to maintain homeostasis in the healthy liver. Constant priming and regulation ensure that appropriate immune activation occurs when challenged by pathogens and tissue damage. Failure to accurately discriminate, regulate, or effectively resolve inflammation offsets this balance, jeopardizing overall tissue health resulting from an either  overly tolerant or an overactive inflammatory response. Compelling scientific and clinical evidence links dysregulated hepatic immune and inflammatory responses upon sterile injury to several pathological conditions in the liver, particularly nonalcoholic steatohepatitis and ischemia-reperfusion injury. Murine and human studies have described interactions between diverse immune repertoires and nonhematopoietic cell populations in both physiological and pathological activities in the liver, although the molecular mechanisms driving these associations are not clearly understood. Here, we review the dynamic roles of inflammatory mediators in responses to sterile injury in the context of homeostasis and disease, the clinical implications of dysregulated hepatic immune activity and therapeutic developments to regulate liver-specific immunity.

Activin-A causes Hepatic stellate cell activation via the induction of TNFα and TGFβ in Kupffer cells

BACKGROUND & AIMS

TGFβ superfamily member Activin-A is a multifunctional hormone/cytokine expressed in multiple tissues and cells, where it regulates cellular differentiation, proliferation, inflammation and tissue architecture. High activin-A levels have been reported in alcoholic cirrhosis and non-alcoholic steatohepatitis (NASH). Our aim was to identify the cell types involved in the fibrotic processes induced by activin-A in liver and verify the liver diseases that this molecule can be found increased.

METHODS

We studied the effect of activin-A on mouse primary Kupffer cells (KCs) and Hepatic Stellate cells (HSCs) and the levels of activin-A and its inhibitor follistatin in the serum of patients from a large panel of liver diseases.

RESULTS

Activin-A is expressed by mouse hepatocytes, HSCs and Liver Sinusoid Endothelial cells but not KCs. Each cell type expresses different activin receptor combinations. HSCs are unresponsive to activin-A due to downregulation/desensitization of type-II activin receptors, while KCs respond by increasing the expression/production of TNFα και TGFβ1. In the presence of KCs or conditioned medium from activin-A treated KCs, HSCs switch to a profibrogenic phenotype, including increased collagen and αSMA expression and migratory capacity. Incubation of activin-A treated KC conditioned medium with antibodies against TNFα and TGFβ1 partially blocks its capacity to activate HSCs. Only patients with alcoholic liver diseases and NASH cirrhosis have significantly higher activin-A levels and activin-A/follistatin ratio.

CONCLUSIONS

Activin-A may induce fibrosis in NASH and alcoholic cirrhosis via activation of KCs to express pro-inflammatory molecules that promote HSC-dependent fibrogenesis and could be a target for future anti-fibrotic therapies.

Activins and Follistatin in Chronic Hepatitis C and Its Treatment with Pegylated-Interferon-α Based Therapy

Pegylated-interferon-α based therapy for the treatment of chronic hepatitis C (CHC) is considered suboptimal as not all patients respond to the treatment and it is associated with several side effects that could lead to dose reduction and/or termination of therapy. The currently used markers to monitor the response to treatment are based on viral kinetics and their performance in the prediction of treatment outcome is moderate and does not combine accuracy and their values have several limitations. Hence, the development of new sensitive and specific predictor markers could provide a useful tool for the clinicians and healthcare providers, especially in the new era of interferon-free therapy, for the classification of patients according to their response to the standard therapy and only subscribing the novel directly acting antiviral drugs to those who are anticipated not to respond to the conventional therapy and/or have absolute contraindications for its use. The importance of activins and follistatin in the regulation of immune system, liver biology, and pathology has recently emerged. This review appraises the up-to-date knowledge regarding the role of activins and follistatin in liver biology and immune system and their role in the pathophysiology of CHC.

Increased serum activin-A differentiates alcoholic from cirrhosis of other aetiologies

BACKGROUND

Activin-A is a molecule of the TGF superfamily, implicated in liver fibrosis, regeneration and stem cell differentiation. However, data on activins in liver diseases are few. We therefore studied serum levels of activin-A in chronic liver diseases. To identify the origin of activin-A, levels in the hepatic vein were also estimated.

MATERIALS AND METHODS

Nineteen controls and 162 patients participated in the study: 39 with hepatocellular carcinoma (HCC: 19 viral associated and 20 alcohol associated), 18 with chronic hepatitis C (CHC), 47 with primary biliary cirrhosis (26 PBC stage I-II and 21 stage IV), 22 with alcoholic cirrhosis (AC, hepatic vein blood available in 16), 20 with HCV cirrhosis (hepatic vein blood available in 18) and 16 patients with alcoholic fatty liver with mild to moderate fibrosis but no cirrhosis.

RESULTS

Activin-A levels were significantly increased (P < 0·001) in serum of patients with AC (median 673 pg/mL, range 449-3279), compared with either controls (149 pg/mL, 91-193) or patients with viral cirrhosis (189 pg/mL, 81-480), CHC (142 pg/mL, 65-559) PBC stage I-II (100 pg/mL, 59-597) and PBC stage IV (104 pg/mL, 81-579). Only patients with AC-associated HCC had significantly increased levels of activin-A (2403 pg/mL, 1561-7220 pg/mL). Activin-A serum levels could accurately discriminate AC from cirrhosis of other aetiologies and noncirrhotic alcoholic fatty liver with fibrosis.

CONCLUSIONS

Increased serum levels of activin-A only in patients with alcohol-related cirrhosis or HCC suggest a possible role of this molecule in the pathophysiology of AC. Further research is warranted to elucidate its role during the profibrotic process and its possible clinical applications.

The regulation and functions of activin and follistatin in inflammation and immunity

The activins are members of the transforming growth factor β superfamily with broad and complex effects on cell growth and differentiation. Activin A has long been known to be a critical regulator of inflammation and immunity, and similar roles are now emerging for activin B, with which it shares 65% sequence homology. These molecules and their binding protein, follistatin, are widely expressed, and their production is increased in many acute and chronic inflammatory conditions. Synthesis and release of the activins are stimulated by inflammatory cytokines, Toll-like receptor ligands, and oxidative stress. The activins interact with heterodimeric serine/threonine kinase receptor complexes to activate SMAD transcription factors and the MAP kinase signaling pathways, which mediate inflammation, stress, and immunity. Follistatin binds to the activins with high affinity, thereby obstructing the activin receptor binding site, and targets them to cell surface proteoglycans and lysosomal degradation. Studies on transgenic mice and those with gene knockouts, together with blocking studies using exogenous follistatin, have established that activin A plays critical roles in the onset of cachexia, acute and chronic inflammatory responses such as septicemia, colitis and asthma, and fibrosis. However, activin A also directs the development of monocyte/macrophages, myeloid dendritic cells, and T cell subsets to promote type 2 and regulatory immune responses. The ability of both endogenous and exogenous follistatin to block the proinflammatory and profibrotic actions of activin A has led to interest in this binding protein as a potential therapeutic for limiting the severity of disease and to improve subsequent damage associated with inflammation and fibrosis. However, the ability of activin A to sculpt the subsequent immune response as well means that the full range of effects that might arise from blocking activin bioactivity will need to be considered in any therapeutic applications.

Activins and follistatins: Emerging roles in liver physiology and cancer

Activins are secreted proteins belonging to the TGF-β family of signaling molecules. Activin signals are crucial for differentiation and regulation of cell proliferation and apoptosis in multiple tissues. Signal transduction by activins relies mainly on the Smad pathway, although the importance of crosstalk with additional pathways is increasingly being recognized. Activin signals are kept in balance by antagonists at multiple levels of the signaling cascade. Among these, follistatin and FLRG, two members of the emerging family of follistatin-like proteins, can bind secreted activins with high affinity, thereby blocking their access to cell surface-anchored activin receptors. In the liver, activin A is a major negative regulator of hepatocyte proliferation and can induce apoptosis. The functions of other activins expressed by hepatocytes have yet to be more clearly defined. Deregulated expression of activins and follistatin has been implicated in hepatic diseases including inflammation, fibrosis, liver failure and primary cancer. In particular, increased follistatin levels have been found in the circulation and in the tumor tissue of patients suffering from hepatocellular carcinoma as well as in animal models of liver cancer. It has been argued that up-regulation of follistatin protects neoplastic hepatocytes from activin-mediated growth inhibition and apoptosis. The use of follistatin as biomarker for liver tumor development is impeded, however, due to the presence of elevated follistatin levels already during preceding stages of liver disease. The current article summarizes our evolving understanding of the multi-faceted activities of activins and follistatins in liver physiology and cancer.

Intracrine signalling of activin A in hepatocytes upregulates connective tissue growth factor (CTGF/CCN2) expression

BACKGROUND/AIMS

Up to now, the effect of activin A on the expression of the important transforming growth factor (TGF)-beta downstream modulator connective tissue growth factor (CTGF) is not known, but might be of relevance for the functional effects of this cytokine on several liver cell types.

METHODS

In this study, activin A-dependent CTGF expression in hepatocytes (PC) primed by exogenous activin A and in PC maintained under complete activin-free culture conditions was analysed by Western blots, metabolic labelling, gene silencing, reverse transcriptase-polymerase chain reaction (RT-PCR) and CTGF reporter gene assays. This study was supplemented by immunocytochemical staining of activin A and CTGF in PC of injured liver.

RESULTS

Using alkaline phosphatase alpha-alkaline phosphatase staining, it is demonstrated that activin A becomes increasingly detectable during the course of CCl(4)-liver damage. Addition of activin A to cultured PC induced CTGF protein expression via phosphorylation of Smad2 and Smad3. This induction can be inhibited by the antagonist follistatin and alpha-activin A antibody respectively. When PC were cultured under serum(i.e. activin A)-free culture conditions, a time-dependent increase of activin expression during the course of the culture was proven by RT-PCR. Silencing of inhibin beta(A) gene expression under serum-free conditions by small interfering RNAs greatly suppressed CTGF synthesis and the phosphorylations of Smad2 and Smad3. However, both the extracellularly acting follistatin and the alpha-activin A antibody could not inhibit spontaneous CTGF expression, which, however, was achieved by the cell-permeable TGF-beta Alk4/Alk5 receptor-kinase-inhibitor SB431542.

CONCLUSIONS

In conclusion, the results point to activin A as an inducer of CTGF synthesis in PC. Intracellular activin A contributes to spontaneous CTGF expression in PC independent of exogenous activin A, which is proposed to occur via Alk4/Alk5-receptors. The findings might be important for many actions of activin A on the liver.

Activins and activin antagonists in hepatocellular carcinoma

In many parts of the world hepatocellular carcinoma (HCC) is among the leading causes of cancer-related mortality but the underlying molecular pathology is still insufficiently understood. There is increasing evidence that activins, which are members of the transforming growth factor β (TGFβ) superfamily of growth and differentiation factors, could play important roles in liver carcinogenesis. Activins are disulphide-linked homo- or heterodimers formed from four different β subunits termed βA, βB, βC, and βE, respectively. Activin A, the dimer of two βA subunits, is critically involved in the regulation of cell growth, apoptosis, and tissue architecture in the liver, while the hepatic function of other activins is largely unexplored so far. Negative regulators of activin signals include antagonists in the extracellular space like the binding proteins follistatin and FLRG, and at the cell membrane antagonistic co-receptors like Cripto or BAMBI. Additionally, in the intracellular space inhibitory Smads can modulate and control activin activity. Accumulating data suggest that deregulation of activin signals contributes to pathologic conditions such as chronic inflammation, fibrosis and development of cancer. The current article reviews the alterations in components of the activin signaling pathway that have been observed in HCC and discusses their potential significance for liver tumorigenesis.

Activin receptor-interacting protein 2 expression and its biological function in mouse hepatocytes

AIM: To investigate the activin receptor-interacting protein 2 (ARIP2) expression and its biological function in hepatocytes.

METHODS: Expression of ARIP2 in mouse liver tissue and hepatoma cell line Hepal-6 cells was detected by Western blot, immunohistochemistry and cytochemical staining. Effect of ARIP2 on activin-induced gene transcription was analyzed using CAGA-lux plasmid. Effect of over-expression of ARIP2 on the proliferation of Hepal-6 cells was assayed with MTT method.

RESULTS: ARIP2 was expressed in mouse liver tissue and Hepal-6 cells. The expression of ARIP2 in activin A-stimulated Hepal-6 cells was increased in a time-dependent manner, and peaked at 24 h. There was a significant difference in the expression level of ARIP2 on Hepal-6 cells at 12 and 24 h in contrast with the control group (1.01 ± 0.16, 1.62 ± 0.26 vs 0.82 ± 0.11, P < 0.05, P < 0.01). pcDNA3-ARIP2-transfected Hepal-6 cells obviously suppressed the gene transcription induced by activin A. MTT assay displayed that activin A (5 μg/L and 10 μg/L) remarkably inhibited the proliferation of Hepal-6 cells, the A₅₇₀ nm value was 1.59 ± 0.03 and 1.49 ± 0.04 vs 1.79±0.07, respectively (P < 0.05, P < 0.01). ARIP2 over-expression in Hepal-6 cells significantly blocked the inhibitory effects of activin A (5 μg/L and 10 μg/L) on the proliferation of Hepal-6 cells.

CONCLUSION: ARIP2 can be expected to become a regulation target of genes in treatment of liver injury induced by activin.

Regulation of activin receptor-interacting protein 2 expression in mouse hepatoma Hepa1-6 cells and its relationship with collagen type IV

AIM: To investigate the regulation of activin receptor-interacting protein 2 (ARIP2) expression and its possible relationships with collagen type IV (collagen IV) in mouse hepatoma cell line Hepal-6 cells.

METHODS: The ARIP2 mRNA expression kinetics in Hepal-6 cells was detected by RT-PCR, and its regulation factors were analyzed by treatment with signal transduction activators such as phorbol 12-myristate 13-acetate (PMA), forskolin and A23187. After pcDNA3-ARIP2 was transfected into Hepal-6 cells, the effects of ARIP2 overexpression on activin type II receptor (ActRII) and collagen IV expression were evaluated.

RESULTS: The expression levels of ARIP2 mRNA in Hapel-6 cells were elevated in time-dependent manner 12 h after treatment with activin A and endotoxin LPS, but not changed evidently in the early stage of stimulation (2 or 4 h). The ARIP2 mRNA expression was increased after stimulated with signal transduction activators such as PMA and forskolin in Hepal-6 cells, whereas decreased after treatment with A23187 (25.3% ± 5.7% vs 48.1% ± 3.6%, P < 0.01). ARIP2 overexpression could remarkably suppress the expression of ActRIIA mRNA in dose-dependent manner, but has no effect on ActRIIB in Hepal-6 cells induced by activin A. Furthermore, we have found that overexpression of ARIP2 could inhibit collagen IV mRNA and protein expressions induced by activin A in Hapel-6 cells.

CONCLUSION: These findings suggest that ARIP2 expression can be influenced by various factors. ARIP2 may participate in the negative feedback regulation of signal transduction in the late stage by affecting the expression of ActRIIA and play an important role in regulation of development of liver fibrosis induced by activin.

The activin axis in liver biology and disease

Activins are a closely related subgroup within the TGFbeta superfamily of growth and differentiation factors. They consist of two disulfide-linked beta subunits. Four mammalian activin beta subunits termed beta(A), beta(B), beta(C), and beta(E), respectively, have been identified. Activin A, the homodimer of two beta(A) subunits, has important regulatory functions in reproductive biology, embryonic development, inflammation, and tissue repair. Several intra- and extracellular antagonists, including the activin-binding proteins follistatin and follistatin-related protein, serve to fine-tune activin A activity. In the liver there is compelling evidence that activin A is involved in the regulation of cell number by inhibition of hepatocyte replication and induction of apoptosis. In addition, activin A stimulates extracellular matrix production in hepatic stellate cells and tubulogenesis of sinusoidal endothelial cells, and thus contributes to restoration of tissue architecture during liver regeneration. Accumulating evidence from animal models and from patient data suggests that deregulation of activin A signaling contributes to pathologic conditions such as hepatic inflammation and fibrosis, acute liver failure, and development of liver cancer. Increased production of activin A was suggested to be a contributing factor to impaired hepatocyte regeneration in acute liver failure and to overproduction of extracellular matrix in liver fibrosis. Recent evidence suggests that escape of (pre)neoplastic hepatocytes from growth control by activin A through overexpression of follistatin and reduced activin production contributes to hepatocarcinogenesis. The role of the activin subunits beta(C) and beta(E), which are both highly expressed in hepatocytes, is still quite incompletely understood. Down-regulation in liver tumors and a growth inhibitory function similar to that of beta(A) has been shown for beta(E). Contradictory results with regard to cell proliferation have been reported for beta(C). The profound involvement of the activin axis in liver biology and in the pathogenesis of severe hepatic diseases suggests activin as potential target for therapeutic interventions.

Roles of activin A and hepatocellular apoptosis in the anti-liver fibrosis process induced by Ginkgo biloba extract in rats

AIM: To investigate the effects of Ginkgo biloba extract (GBE) on CCl₄-induced liver fibrosis as well as the underlying mechanisms.

METHODS: Thirty adult male Sprague Dawley rats were randomized into 3 groups: control group (n = 10), model group (n = 10) and treatment group (n = 10). Except the rats in the control group, the others were intraperitoneally injected with 500 mL/L CCl₄ (1 mL/kg) to induce liver cirrhosis (twice a week, for 8 weeks). Moreover, the rats in treatment group were intragastrically administered with GBE (0.4 g/kg) for 8 weeks. At the end of the 8^th week, all the rats were sacrificed. Blood samples were collected for the determination of biochemical indicators. Tissue samples were used for histopathological examinations. The expression of activin A was determined by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). Hepatocellular apoptosis was determined by the method of terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) method.

RESULTS: The grade of liver fibrosis in treatment group was lower than that in the model group (P < 0.05). The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and albumin (ALB) in treatment group were significantly improved as compared with those in the model group (ALT: 2806.9 ±576.1 nkat/L vs 4452.9 ± 709.5 nkat/L; AST: 5314.2 ± 1042 nkat/L vs 15 743.4 ± 625.8 nkat/L; ALB: 31.0 ± 2.1 g/L vs 21.7 ± 1.8 g/L; all P < 0.05). GBE treatment markedly reduced mRNA and protein levels of activin A (mRNA: 0.42 ± 0.09 vs 0.78 ± 0.15; protein: 4.2 ± 0.8 vs 11.4 ± 1.2; both P < 0.01). In comparison with that in the model group, the apoptosis index was decreased in treatment groups (7.56 ± 3.36 vs 16.06 ± 8.84, P < 0.01).

CONCLUSION: GBE can markedly attenuate the degrees of hepatic fibrosis, and the mechanism may be correlated with the expression of activin A and hepatocellular apoptosis.

Expression and significance of Smad4 in colorectal carcinoma tissue

AIM: To investigate the role of Smad4 protein in colorectal carcinogenesis.

METHODS: Expression of Smad4 was detected in 70 cases of normal tissues and colorectal tumor by a streptavidin-peroxidase conjugation method (S-P).

RESULTS: Smad4 expression was significantly lower in colorectal carcinoma (n = 52) than that in the normal tissues (n = 7) and was related to the tumor stages, differentiation and metastasis (lymph node or blood) (P < 0.05).

CONCLUSION: Down-regulation of Smad4 expression may be associated with the carcinogenesis, and Smad4 may play a role in invasion and metastasis of colorectal carcinoma.

Effect of transfected DPC4 gene on angiogenesis of colon carcinoma

AIM: To study the mechanism of transfected DPC4 gene on angiogenesis.

METHODS: SW620 cells were transfected with PcDNA3.1-DPC4 plasmid by using lipofectamine transfecting technique. Expression of Smad4 in DPC₄⁺-SW620 cells was observed by Western blot. The expression of VEGF protein in the cell supernatant was detected by ELISA, and VEGF mRNA by RT-PCR. The model of nude mice inoculated with DPC₄⁺-SW620 cells was established by injecting into flank subcutaneously. The expression of VEGF protein and the microvessel density of tumor tissue in nude mice were detected by immunohistochemical staining (SP method).

RESULTS: DPC₄⁺-SW620 cells expressing Smad4 were harvested; Smad4 protein showed stronger expression in SW620 cells transfected with PcDNA-DPC4 plasmid than that in not-transfected SW620 cells and SW620 cells transfected with blank plasmid, and the positive signal was localized in cytoplasm and nucleus, mainly in cytoplasm; There were lower expression of VEGF protein and mRNA in DPC₄⁺- SW620 cells than that in SW620 cells and PcDNA-SW620 cells (P < 0.05); The model of nude mice inoculated with colon carcinoma cells was established successfully. The tumors of nude mice inoculated with DPC₄⁺-SW620 cells growed more slowly than that inoculated with SW620 cells and PcDNA-SW620 cells. The volume and mass of tumors in nude mice inoculated with DPC₄⁺-SW620 cells were smaller and lighter than those with SW620 cells and PcDNA- SW620 cells (P < 0.05). The expression of VEGF and the microvessel density in DPC₄⁺-SW620 cells were lower than those in SW620 cells and PcDNA-SW620 cells (P < 0.05).

CONCLUSION: The DPC4 gene can suppress the growth of the tumors in nude mice inoculated with DPC₄⁺-SW620 cells; The inhibitory effect of DPC4 on colon carcinoma may be partly mediated by suppressing angiogenesis of tumor.

Gene expression profiles in liver cirrhosis and normal liver tissues

AIM: To describe liver specific gene expression profiles and to identify genes with differential expression between liver cirrhotic tissues and normal liver tissues.

METHODS: The cDNA probes which were labeled with α-³²P dATP were synthesized from total RNAs of liver cirrhosis and normal liver tissues and hybridized to two identical Atlas human cDNA expression arrays membranes containing 588 known genes respectively.

RESULTS: Autoradiographic results were analyzed by specific AtlasImage^TM (version1.01a) software. Among the 588 genes analyzed, 17 genes were found up-regulated in cirrhosis, including integrin beta 7 and collagen type XVIII, and 98 genes were down-regulated in cirrhosis, including TFDP2, BAK and ABL. Expression of the genes was associated with the regulation of cell proliferation, apoptosis, differen-tiation, cell-cell interaction, invasion regulators and cytokines altered.

CONCLUSION: The results obtained from Atlas microarray provide a comprehensive liver cirrhosis specific expression profile. These results may be helpful for identification of target genes for diagnosis and designing rational therapeutic strategies.

Pathomorphological study on location and distribution of Kupffer cells in hepatocellular carcinoma

AIM: To clarify the location and distribution of Kupffer cells in hepatocellular carcinoma (HCC), and to investigate their role in hepatocarcinogenesis.

METHODS: Kupffer cells were immunohistochemically stained by streptavadin-peroxidase conjugated method (S-P). The numbers of Kupffer cells in cancerous, para-cancerous and adjacent normal liver tissues of 48 HCCs were comparatively examined.

RESULTS: The mean number of Kupffer cells in cancerous, para-cancerous and adjacent normal liver tissues was 12.7 ± 6.8, 18.1 ± 8.2 and 18.9 ± 7.9 respectively. The number of Kuppfer cells in cancerous tissues was significantly lower than that in para-cancerous tissues (t = 2.423, P < 0.05) and adjacent normal liver tissues (t = 2.521, P < 0.05). As tumor size increased, the number of Kupffer cells in cancerous tissues significantly decreased (F = 4.61, P < 0.05). Moreover, there was also a significant difference in the number of Kupffer cells among well-differentiated, moderately-differentiated and poorly-differentiated cases(F = 4.49, P < 0.05).

CONCLUSION: This study suggests that decrease of Kupffer cells in HCCs may play an important role in the carcinogenesis of HCC, the number of Kupffer cells in HCC is closely related to the size and differentiation grade of the tumor.

Effects of estradiol on type I, III collagens and TGF β1 in hepatic fibrosis in rats

AIM

To study the effects of estradiol on the production of collagen I, III and transforming growth factor β₁ (TGF β₁) in experimental fibrosis in rats induced by carbon tetrachloride (CCL4), and to investigate the suppressive effects of estrogen on liver fibrosis.

METHODS

Rats were randomly allocated into a normal control group, a model control group, a therapy control group and an estradiol group. Liver fibrosis was induced by CCL₄ administration. The estradiol group, apart from the administration of CCL₄, was treated subcutaneously with estradiol (benzoic estradiol) 1 mg/kg twice weekly. At the end of week 8, all the rats were sacrificed. Liver inflammation and collagen deposition were observed with HE and Masson's collagen stains, analyzed with scoring and staging systems. Type I, III collagens and TGF β₁ were observed with immunohistochemical method.

RESULTS

CCL₄ group had the typical liver fibrosis compared with normal control group. The fibrous septa were formed in CCL₄ group rats, and collagens were accumulated and deposited in the sinusoids and liver lobules. The expression of type I , III collagens (0.58±0.26 vs 6.34±2.24, 1.07±0.49 vs 5.28±1.28, P<0.001) and TGF β₁ was significantly increased. Estradiol significantly attenuated collagen accumulation (P<0.05) in the fibrotic livers, and decreased type I , III collagens (2.47±0.76 vs 6.34±2.24, 3.02±1.20 vs 5.28±1.28, P<0.05) and TGF β₁ expression in the liver.

CONCLUSION

Estradiol treatment reduces the synthesis of hepatic type I , III collagens and TGF β₁ in the fibrotic liver induced by CCL₄ administration, and attenuates hepatic fibrosis.

Suppression of expression extracellular matrix in hepatic fibrosis rat with tetrandrine and glycyrrhizinic acid

AIM

To investigate effects and mechanism of tetrandrine(Tet) and glycyrrhizinic acid(Glz) in combination on metabolism of extracellular matrix in hepatic fibrotic rats induced by carbon tetrachloride.

METHODS

The hepatic fibrosis model rats induced with carbon tetrachloride were grouped randomly into 5 mg/kg, 10 mg/kg, 20 mg/kg Tet, 5 mg/kgTet+50 mg/kgGlz, 10 mg/kgTet+50 mg/kgGlz, 20 mg/kgTet+50 mg/kgGlz and 50 mg/kgGlz groups. Rats in experimental groups were administrated with Tet and or Glz by gavage or peritoneal injection every day. Serum levels of HA, LN, and PIIIP were detected with radioimmunoassay. Histopathological change was examined with VG staining and observed under light-microscope. mRNA of collagen type I and III were evaluated by RT-PCR.

RESULTS

In comparison with model group, Tet and Glz in combination could markedly decrease serum levels of HA, LN and PIIIP(121.8±9.5 vs 58.4±7.6, 85.7±12.1 vs 46.2±7.3, 35.9±3.5 vs 23.5±2.9; P<0.05), and suppress the expressions of type I, III procollagen mRNA(0.53±0.07 vs 0.26±0.09, 0.47±0.05 vs 0.21±0.07; P<0.05), and reduce deposition of extracellular matrix. Compared with Tet (10mg/kg)only group, Tet with Glz in combination could markedly reduced the serum levels of HA, LN and PIIIP(69.2±11.1 vs 58.4±7.6; 52.3±6.7 vs 46.2±7.3; 29.9±3.2 vs 23.5±2.9; P<0.05), and inhibit the expression of type I, III procollagen mRNA(0.33±0.06 vs 0.26±0.09, 0.29±0.04 vs 0.21±0.07; P<0.05).

CONCLUSION

Tet and Glz in combination could inhibit expression and deposition of extracellular matrix in fibrotic rats more significantly than either Tet or Glz.

Effect of Activin on extracelluar matrix secretion in isolated rat hepatic stellate cell

AIM

To investigate the effect of activin A on the extracelluar matrix secretion of rat hepatic stellate cell.

METHODS

Hepatic stellate cells were isolated and purified from normal male Sprague-Dawley rat liver by a combination of pronase-collagenase perfusion and density gradient centrifugation. Passaged hepatic stellate cells were divided randomly into eight groups: control group(A group), ACTA 1 μg/L group (B group), ACTA 10 μg/L group(C group), ACTA 100 μg/L group (D group), TGF β₁ 10 μg/L group(E group), TGF β₁ 10 μg/L plus ACTA 1 μg/L group(F group), TGF β₁ 10 μg/L plus ACTA 10 μg/L group(G group), TGF β₁ 10 μg/L plus ACTA 100 μg/L group(H group). 24 h after incubation secretion of procollagen Ⅲ, collagen Ⅳ and mRNA of collagen Ⅲ in hepatic stellate cells were detected by radioimmunoassays and semi-quantitative RT-PCR method respectively.

RESULTS

Extracellular matrix secretion in passaged hepatic stellate cells was enhanced by activin A according to its concentration, the capacity of extracellular matrix secretion by 100 μg/L activin A was equal to that of 10 μg/L TGF β₁, extracellular matrix secretion and type Ⅲ collagen mRNA expression in passaged hepatic stellate cells was enhanced by activin A and TGFβ₁ in a synergistic manner.

CONCLUSION

Activin A may contribute to hepatic fibrogenesis.

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Estrogen reduces CCL4- induced liver fibrosis in rats

AIM: Chronic liver diseases, such as fibrosis or cirrhosis, are more common in men than in women. This gender difference may be related to the effects of sex hormones on the liver. The aim of the present work was to investigate the effects of estrogen on CCL₄-induced fibrosis of the liver in rats.

METHODS: Liver fibrosis was induced in male, female and ovariectomized rats by CCL₄ administration. All the groups were treated with estradiol (1 mg/kg) twice weekly. And tamoxifen was given to male fibrosis model. At the end of 8 wk, all the rats were killed to study serum indicators and the livers.

RESULTS: Estradiol treatment reduced aspartate aminotransferase (AST), alanine aminotransferase (ALT), hyaluronic acid (HA) and type IV collagen (CIV) in sera, suppressed hepatic collagen content, decreased the areas of hepatic stellate cells (HSC) positive for α-smooth muscle actin (α-SMA), and lowered the synthesis of hepatic type I collagen significantly in both sexes and ovariectomy fibrotic rats induced by CCL₄ administration. Whereas, tamoxifen had the opposite effect. The fibrotic response of the female liver to CCL₄ treatment was significantly weaker than that of male liver.

CONCLUSION: Estradiol reduces CCL₄-induced hepatic fibrosis in rats. The antifibrogenic role of estrogen in the liver may be one reason for the sex associated differences in the progression from hepatic fibrosis to cirrhosis.

Salvia miltiorrhiza monomer IH764-3 induces hepatic stellate cell apoptosis via caspase-3 activation

AIM: To investigate the effects of IH764-3 on HSC apoptosis, and the expression of caspase-3 protein in HSC apoptotic process.

METHODS: HSCs were cultured in medium with different IH764-3 doses (10 μg·mL^-1, 20 μg·mL^-1, 30 μg·mL^-1, 40 μg·mL^-1) and without IH764-3, and HSC proliferation was quantitatively measured by ³H-thymidine incorporation. The morphological changes of HSCs were observed with transmission electron microscope after exposure to the dose of 40 μg·mL^-1 of IH764-3 for 48 hr. The apoptosis rates were detected by annexin V/PI and TdT-mediated dUTP nick end labeling (TUNEL). The expression of caspase-3 protein was determined by flow cytometry.

RESULTS: (1) HSC proliferation rates induced with different IH764-3 doses (10 μg·mL^-1, 20 μg·mL^-1, 30 μg·mL^-1, 40 μg·mL^-1) were significantly reduced compared with that of the control group (P < 0.01). (2) With the doses above, IH764-3 dose-dependently produced HSC apoptosis rates of 6.7% (9.4%), 9.3% (21.6%), 15.1% (27.2%) and 19.0% (28.4%) respectively, by annexin V and PI-labeled flow cytometry assay (or TUNEL), while it was only 2.3% (6.7%) in the control. (3) The expression of caspase-3 protein in IH764-3 groups was significantly higher than that of the control (P < 0.05).

CONCLUSION: Within the dose range used in present study, IH764-3 can inhibit HSC proliferation, as well as enhance HSC apoptosis. Furthermore, IH764-3 can significantly increase the caspase-3 protein expression.

Regulating effect of Chinese herbal medicine on the peritoneal lymphatic stomata in enhancing ascites absorption of experimental hepatofibrotic mice

AIM

To observe the regulatory effect of Chinese herbal medicine on peritoneal lymphatic stomata and its significance in treating ascites in liver fibrosis model mice.

METHODS

Two Chinese herbal composite prescriptions were used separately to treat the carbon tetrachloride-induced mouse model of liver fibrosis. The histo-pathologic changes of the liver sections (HE and VG stainings) were observed. The peritoneal lymphatic stomata was detected by scanning electron microscopy and computer image processing. The changes of urinary volume and sodium ion concentration were measured.

RESULTS

In the model group, lots of fibrous tissue formed in liver and extended into the hepatic lobules to separate them incompletely. In the treated and prevention groups, the histo-pathologic changes of liver was rather milder, only showed much less fibrous tissue proliferation in the hepatic lobules. The peritoneal lymphatic stomata enlarged with increased density in the experimental groups (diameter: PA, 3.07 +/- 0.69 microm; PB, 2.82 +/- 0.37 microm; TA, 3.25 +/- 0.82 microm and TB, 2.82 +/- 0.56 microm; density: PA, 7.11 +/- 1.90 stomata.1000 microm(-2); PB, 8.76 +/- 1.45 stomata.1000 microm(-2); TA, 6.55 +/- 1.44 stomata.1000 microm(-2)and TB, 8.76+/-1.79 stomata.1000 microm(-2)), as compared with the model group (diameter: 2.00+/-0.52 microm density: 4.45+/-1.05 stomata.1000 microm(-2)). After treatment, the urinary volume and sodium ion excretion increased in the experimental groups (PA, 231.28+/-41.09 mmol.L(-1); PB, 171.69 +/- 27.48 mmol.L(-1) and TA, 231.44 +/- 34.12 mmol.L(-1)), which were significantly different with those in the model group (129.33 +/- 36.75 mmol.L(-1)).

CONCLUSION

Chinese herbal medicine has marked effects in alleviating liver fibrosis, regulating peritoneal lymphatic stomata, improving the drainage of ascites from peritoneal cavity and causing increase of urinary volume and sodium ion excretion to reduce the water and sodium retention, and thus have favorable therapeutic effect in treating ascites.

TECA hybrid artificial liver support system in treatment of acute liver failure

AIM: To assess the efficacy and safety of TECA type hybr id artificial liver support system (TECA-HALSS) in providing liver function of detoxification, metabolism and physiology by treating the patients with acute liv er failure (ALF).

METHODS: The porcine liver cells (1-2) × 10¹⁰ were separated from the Chinese small swine and cultured in the bioreactor of TECA-BALSS at 37.0 °C and circulated through the outer space of the hollow fiber tubes in BALSS. The six liver failure patients with various degree of hepatic coma were treated by TECA-HALSS and with conventional medicines. The venous plasma of the patients was separated by a plasma separator and treated by charcoal adsorbent or plasma exchange. The plasma circulated through the inner space of the hollow fiber tubes of BALSS and mixed with the patients’ blood cells and flew back to their blood circulation. Some small molecular weight substances were exchanged between the plasma and porcine liver cells. Each treatment lasted 6.0-7.0 h. Physiological and biochemical parameters were measured before, during and after the treatment.

RESULTS: The average of porcine liver cells was (1.0-3.0) × 10¹⁰ obtained from each swine liver using our modified enzymatic digestion method. The survival rate of the cells was 85%-93% by trypan blue stain and AO/PI fluorescent stain. After cultured in TECA-BALSS bioreactor for 6 h, the survival rate of cells still remained 70%-85%. At the end of TECA-HALSS treatment, the levels of plasma NH₃, ALT, TB and DB were significantly decreased. The patients who were in the state of drowsiness or coma before the treatment improved their appetite significantly and regained consciousness, some patients resumed light physical work on a short period after the treatment. One to two days after the treatment, the ratio of PTA increased warkedly. During the treatment, the heart rates, blood pressure, respiration condition and serum electrolytes (K⁺, Na⁺ and Cl^-) were stable without thrombosis and bleeding in all the six patients.

CONCLUSION: TECA-HALSS treatment could be a rapid, safe and efficacious method to provide temporary liver support for patients with ALF.