Production of pro- and anti-fibrotic agents by rat Kupffer cells; the effect of octreotide

Is There a Place for Somatostatin Analogues for the Systemic Treatment of Hepatocellular Carcinoma in the Immunotherapy Era?

Patients with advanced hepatocellular carcinoma (HCC) have a very limited survival rate even after the recent inclusion of kinase inhibitors or immune checkpoint inhibitors in the therapeutic armamentarium. A significant problem with the current proposed therapies is the considerable cost of treatment that may be a serious obstacle in low- and middle-income countries. Implementation of somatostatin analogues (SSAs) has the potential to overcome this obstacle, but due to some negative studies their extensive evaluation came to a halt. However, experimental evidence, both in vitro and in vivo, has revealed various mechanisms of the anti-tumor effects of these analogues, including inhibition of cancer cell proliferation and angiogenesis and induction of apoptosis. Favorable indirect effects such as inhibition of liver inflammation and fibrosis and influence on macrophage-mediated innate immunity have also been noted and are presented in this review. Furthermore, the clinical application of SSAs is both presented and compared with clinical trials of kinase and immune checkpoint inhibitors (ICIs). No direct trials have been performed to compare survival in the same cohort of patients, but the cost of treatment with SSAs is a fraction compared to the other modalities and with significantly less serious side effects. As in immunotherapy, patients with viral HCC (excluding alcoholics), as well as Barcelona stage B or C and Child A patients, are the best candidates, since they usually have a survival prospect of at least 6 months, necessary for optimum results. Reasons for treatment failures are also discussed and further research is proposed.

Inhibitory effects of somatostatin analogue in bleomycin-induced pulmonary fibrosis

BACKGROUND AND OBJECTIVES

Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal lung disease. An increased expression of somatostatin receptor subtype 2 in patients with IPF was identified and lung fibroblasts expressed somatostatin receptors in vitro. In addition, somatostatin analogue inhibits the expression of transforming growth factor-β, insulin-like growth factor (IGF) -1, platelet-derived growth factor, and basic fibroblast growth factor. Therefore, we examined the effects of somatostatin analogue on bleomycin-induced pulmonary fibrosis in mice. In a similar model, it has been reported that administration of high-dose somatostatin analogs suppressed acute inflammation and subsequent pulmonary fibrosis. However, it was clarified that the same effect can be obtained even at the dose used in clinical practice.

METHODS

C57BL/6 mice received a single tracheal instillation of bleomycin. After randomly allocated, mice were treated with subcutaneous injection of either normal saline or somatostatin analogue.

RESULTS

Somatostatin analogue reduced the number of neutrophils and lymphocytes in bronchoalveolar lavage (BAL) and IGF-1 level in serum and BAL fluid and attenuated weight loss. The hydroxyproline content of the lung homogenates in somatostatin analogue treatment group was significantly lower than in that of normal saline treatment group.

CONCLUSIONS

These results suggest that somatostatin analogue may attenuate pulmonary fibrosis after bleomycin treatment at the dose used in clinical practice.

Upregulation of KSRP by miR-27b attenuates schistosomiasis-induced hepatic fibrosis by targeting TGF-β1

Hepatic stellate cells (HSCs) are the main effectors for various types of hepatic fibrosis, including Schistosome-induced hepatic fibrosis. Multiple inflammatory cytokines/chemokines, such as transforming growth factor-β1 (TGF-β1), activate HSCs, and contribute to the development of hepatic fibrosis. MicroRNAs regulate gene expression at the posttranscriptional level and are involved in regulation of inflammatory cytokine/chemokine synthesis. In this study, we showed that soluble egg antigen (SEA) stimulation and Schistosoma japonicum infection downregulate miR-27b expression and increase KH-type splicing regulatory protein (KSRP) mRNA and protein levels in vitro and in vivo. miR-27b regulates the stabilization of TGF-β1 mRNA through targeting KSRP by interacting with their AU-rich elements in hepatocytes and non-parenchymal cells, which has an effect on the activation of HSCs. Importantly, our results have shown that either knockdown miR-27b or overexpression of KSRP attenuates S. japonicum-induced hepatic fibrosis in vivo. Therefore, our study highlights the crucial role of miR-27b and KSRP in the negative regulation of immune reactions in hepatocyte and non-parenchymal cells in response to SEA stimulation and S. japonicum infection. It reveals that manipulation of miR-27b or KSRP might be a useful strategy not only for treating Schistosome-induced hepatic fibrosis but also for curing hepatic fibrosis in general.

Modeling the nonlinear behavior of a bioactive peptide in reversed-phase gradient elution chromatography

The thermodynamic behavior of octreotide, a cyclic octapeptide with important pharmaceutical functions, has been simulated under reversed-phase gradient elution conditions. To this end, adsorption behavior was firstly investigated in isocratic conditions, under a variety of water/acetonitrile + 0.02% (v/v) trifluoroacetic acid (TFA) mixtures as mobile phase by using a Langmuir isotherm. Organic modifier was varied in the range between 23 and 28% (v/v). Adsorption isotherms were determined by means of the so-called Inverse Method (IM) with a minimum amount of peptide. The linear solvent strength (LSS) model was used to find the correlation between isotherm parameters and mobile phase composition. This study contributes to enlarge our knowledge on the chromatographic behavior under nonlinear gradient conditions of peptides. In particular, it focuses on a cyclic octapeptide.

Visualisation of interstitial lung disease by molecular imaging of integrin αvβ3 and somatostatin receptor 2

OBJECTIVE

To evaluate integrin αvβ3 (alpha-v-beta-3)-targeted and somatostatin receptor 2 (SSTR2)-targeted nuclear imaging for the visualisation of interstitial lung disease (ILD).

METHODS

The pulmonary expression of integrin αvβ3 and SSTR2 was analysed in patients with different forms of ILD as well as in bleomycin (BLM)-treated mice and respective controls using immunohistochemistry. Single photon emission CT/CT (SPECT/CT) was performed on days 3, 7 and 14 after BLM instillation using the integrin αvβ3-targeting ¹⁷⁷Lu-DOTA-RGD and the SSTR2-targeting ¹⁷⁷Lu-DOTA-NOC radiotracer. The specific pulmonary accumulation of the radiotracers over time was assessed by in vivo and ex vivo SPECT/CT scans and by biodistribution studies.

RESULTS

Expression of integrin αvβ3 and SSTR2 was substantially increased in human ILD regardless of the subtype. Similarly, in lungs of BLM-challenged mice, but not of controls, both imaging targets were stage-specifically overexpressed. While integrin αvβ3 was most abundantly upregulated on day 7, the inflammatory stage of BLM-induced lung fibrosis, SSTR2 expression peaked on day 14, the established fibrotic stage. In agreement with the findings on tissue level, targeted nuclear imaging using SPECT/CT specifically detected both imaging targets ex vivo and in vivo, and thus visualised different stages of experimental ILD.

CONCLUSION

Our preclinical proof-of-concept study suggests that specific visualisation of molecular processes in ILD by targeted nuclear imaging is feasible. If transferred into clinics, where imaging is considered an integral part of patients' management, the additional information derived from specific imaging tools could represent a first step towards precision medicine in ILD.

Esomeprazole ameliorates CCl4 induced liver fibrosis in rats via modulating oxidative stress, inflammatory, fibrogenic and apoptotic markers

BACKGROUND

Hepatic fibrosis is a major health problem that requires further medical attention. Proton pump inhibitors are proven to possess other therapeutic potentials apart of their acid anti-secretory actions.

AIM OF THE WORK

To test possible anti-fibrotic effect of esomeprazole magnesium trihydrate in management of liver fibrosis compared to silymarin, the well-known hepatoprotective agent.

MATERIALS & METHODS

40 male albino rats were divided into 4 groups: normal control group; CCl₄-treated group (1 mL/kg 40% CCl₄, diluted in olive oil) I.P twice weekly for 6 weeks; esomeprazole-treated group (30 mg/kg body weight); and Silymarin-treated group (100 mg/kg body weight). Both esomeprazole and silymarin were given orally daily for two weeks after the last CCl₄ dose. Serum and tissue samples were assessed for histopathological and biochemical analyses.

RESULTS

Esomeprazole reversed hepatocellular damage, improved liver integrity, corrected major histopathological disturbances induced by CCl₄ and lowered fibrosis scoring. It also improved anti-oxidant capacity and attenuated lipid peroxidation. Esomeprazole treatment resulted in down-regulation of hepatic pro-apoptotic Bax and up-regulation of anti-apoptotic Bcl2 protein expressions. In addition, it resulted in inhibition of TNF-α, TGF-β and IL-6 -mediated inflammatory responses, and retrieval of the epithelial marker e-cadherin.

CONCLUSION

Esomeprazole confers significant anti-fibrotic actions. Further study is needed to elucidate other probable mechanisms for this effect and to test their anti-fibrotic potential clinically.

Umbilical cord-derived mesenchymal stem cells alleviate liver fibrosis in rats

AIM: To evaluate the efficacy of umbilical cord-derived mesenchymal stem cells (UC-MSCs) transplantation in the treatment of liver fibrosis.

METHODS: Cultured human UC-MSCs were isolated and transfused into rats with liver fibrosis induced by dimethylnitrosamine (DMN). The effects of UC-MSCs transfusion on liver fibrosis were then evaluated by histopathology; serum interleukin (IL)-4 and IL-10 levels were also measured. Furthermore, Kupffer cells (KCs) in fibrotic livers were isolated and cultured to analyze their phenotype. Moreover, UC-MSCs were co-cultured with KCs in vitro to assess the effects of UC-MSCs on KCs’ phenotype, and IL-4 and IL-10 levels were measured in cell culture supernatants. Finally, UC-MSCs and KCs were cultured in the presence of IL-4 antibodies to block the effects of this cytokine, followed by phenotypical analysis of KCs.

RESULTS: UC-MSCs transfused into rats were recruited by the injured liver and alleviated liver fibrosis, increasing serum IL-4 and IL-10 levels. Interestingly, UC-MSCs promoted mobilization of KCs not only in fibrotic livers, but also in vitro. Co-culture of UC-MSCs with KCs resulted in increased production of IL-4 and IL-10. The addition of IL-4 antibodies into the co-culture system resulted in decreased KC mobilization.

CONCLUSION: UC-MSCs could increase IL-4 and promote mobilization of KCs both in vitro and in vivo, subsequently alleviating the liver fibrosis induced by DMN.

New Concepts on Pathogenesis and Diagnosis of Liver Fibrosis; A Review Article

Liver fibrosis is a potentially reversible response to hepatic insults, triggered by different chronic diseases most importantly viral hepatitis, alcoholic, and nonalcoholic fatty liver disease. In the course of the chronic liver disease, hepatic fibrogenesis may develop, which is attributed to various types of cells, molecules, and pathways. Activated hepatic stellate cell (HSC), the primary source of extracellular matrix (ECM), is fundamental in pathophysiology of fibrogenesis, and thus is the most attractable target for reversing liver fibrosis. Although, liver biopsy has long been considered as the gold standard for diagnosis and staging of hepatic fibrosis, assessing progression and regression by biopsy is hampered by its limitations. We provide recent views on noninvasive approaches including serum biomarkers and radiologic techniques.

The role of Kupffer cells in hepatitis B and hepatitis C virus infections

Globally, over 500 million people are chronically infected with the hepatitis B virus (HBV) or hepatitis C virus (HCV). These chronic infections cause liver inflammation, and may result in fibrosis/cirrhosis or hepatocellular carcinoma. Albeit that HBV and HCV differ in various aspects, clearance, persistence, and immunopathology of either infection depends on the interplay between the innate and adaptive responses in the liver. Kupffer cells, the liver-resident macrophages, are abundantly present in the sinusoids of the liver. These cells have been shown to be crucial players to maintain homeostasis, but also contribute to pathology. However, it is important to note that especially during pathology, Kupffer cells are difficult to distinguish from infiltrating monocytes/macrophages and other myeloid cells. In this review we discuss our current understanding of Kupffer cells, and assess their role in the regulation of anti-viral immunity and disease pathogenesis during HBV and HCV infection.

Kupffer Cells in Health and Disease

Kupffer cells (KC), the resident macrophages of the liver, represent the largest population of mononuclear phagocytes in the body. Phenotypic, developmental, and functional aspects of these cells in steady state and in different diseases are the focus of this review. Recently it has become evident that KC precursors seed the liver already early in fetal development, and the population can be maintained independently from circulating monocytes. However, inflammatory conditions allow rapid differentiation of monocytes into mature cells that are indistinguishable from genuine KC. KC are located in the lumen of sinusoids that receive blood both from the portal vein, carrying nutrients and microbial products from the gut, and from the hepatic artery. This positions KC ideally for their prime function, namely surveillance and clearance of the circulation. As such, they are important in iron recycling by phagocytosing effete erythrocytes, for instance. The immunophenotype of KC, characterized by a wide variety of endocytic receptors, is indicative of this scavenger function. In maintaining homeostasis, KC have an ambivalent response to exogenous triggers. On the one hand, their surveillance function requires alert responses to potentially hazardous substances. On the other hand, continuous exposure of the cells to the trigger-rich content of blood originating from the gut dampens their responsiveness to further stimuli. This ambivalence is also reflected in their diverse roles in disease pathogenesis. For the latter, we sketch the contribution of KC by giving examples of their role in metabolic disease, infections, and liver injury.

Octreotide modulates the effects on fibrosis of TNF-α, TGF-β and PDGF in activated rat hepatic stellate cells

BACKGROUND AND AIMS

Somatostatin and its analogs may influence hepatic fibrosis interfering through several mechanisms. The aim of this study was to investigate the effect of octreotide on cytokine activated hepatic stellate cells (HSC).

METHODS

Primary HSCs were isolated from rats and were cultured on plastic for activation. Expression of somatostatin receptors (SSTR) was investigated in cultured HSCs by immunofluorescence and western blot. The effect of octreotide on cellular proliferation was studied with the MTT assay and western blot for α1-procollagen (α1-PROC) production in TNFα, TGF-β1 or PDGF treated HSCs. Phosphotyrosine (PTP) and phosphoserine-phosphothreonine (STP) phosphatases inhibition was performed with sodium orthovanadate and okadaic acid respectively.

RESULTS

Activated HSC express SSTR subtypes 1, 2A, 2B, 3 and 4 and their expression is enhanced by further HSC activation. Octreotide did not have an effect on HSC proliferation but inhibited plastic induced α1-PROC production. Interestingly, it enhanced PDGF-induced HSC proliferation but inhibited PDGF and TGFβ1 dependent expression of α1-PROC, while an opposite effect was observed in TNFα-induced cell proliferation and collagen production. PTP inhibition reversed the inhibitory effect of octreotide on α1-PROC, but potentiated its effect on PDGF and TGFβ1 dependent α1-PROC production. Finally, STP inhibition profoundly inhibited α1-PROC expression in all cases suggesting that both STP and PTP phosphatases are important regulators of pro-fibrotic mechanisms.

CONCLUSIONS

The net effect of octreotide on HSCs and therefore liver fibrosis is subject to the cytokine microenvironment of these cells. This effect is modulated by PTPs and STPs inhibition. Especially in the case of STPs their profibrotic effects could be an interesting new therapeutic target in liver fibrosis.

Role of PINCH and its partner tumor suppressor Rsu-1 in regulating liver size and tumorigenesis

Particularly interesting new cysteine-histidine-rich protein (PINCH) protein is part of the ternary complex known as the IPP (integrin linked kinase (ILK)-PINCH-Parvin-α) complex. PINCH itself binds to ILK and to another protein known as Rsu-1 (Ras suppressor 1). We generated PINCH 1 and PINCH 2 Double knockout mice (referred as PINCH DKO mice). PINCH2 elimination was systemic whereas PINCH1 elimination was targeted to hepatocytes. The genetically modified mice were born normal. The mice were sacrificed at different ages after birth. Soon after birth, they developed abnormal hepatic histology characterized by disorderly hepatic plates, increased proliferation of hepatocytes and biliary cells and increased deposition of extracellular matrix. After a sustained and prolonged proliferation of all epithelial components, proliferation subsided and final liver weight by the end of 30 weeks in livers with PINCH DKO deficient hepatocytes was 40% larger than the control mice. The livers of the PINCH DKO mice were also very stiff due to increased ECM deposition throughout the liver, with no observed nodularity. Mice developed liver cancer by one year. These mice regenerated normally when subjected to 70% partial hepatectomy and did not show any termination defect. Ras suppressor 1 (Rsu-1) protein, the binding partner of PINCH is frequently deleted in human liver cancers. Rsu-1 expression is dramatically decreased in PINCH DKO mouse livers. Increased expression of Rsu-1 suppressed cell proliferation and migration in HCC cell lines. These changes were brought about not by affecting activation of Ras (as its name suggests) but by suppression of Ras downstream signaling via RhoGTPase proteins. In conclusion, our studies suggest that removal of PINCH results in enlargement of liver and tumorigenesis. Decreased levels of Rsu-1, a partner for PINCH and a protein often deleted in human liver cancer, may play an important role in the development of the observed phenotype.

The phenotypic fate and functional role for bone marrow-derived stem cells in liver fibrosis

Liver fibrosis is an outcome of chronic liver injury of any etiology. It is manifested by extensive deposition of extracellular matrix (ECM) proteins that produce a fibrous scar in the injured liver. Bone marrow (BM) cells may play an important role in pathogenesis and resolution of liver fibrosis. BM cells contribute to the inflammatory response by TGF-β1 secretion and activation of liver resident myofibroblasts. Moreover, BM itself can serve as a source of collagen expressing cells, e.g. BM-derived fibrocytes and mesenchymal progenitors, which in turn, have a potential to in situ differentiate into fibrogenic myofibroblasts and facilitate fibrosis. Finally, BM cells play an active part in resolution of liver fibrosis after cessation of fibrogenic stimuli. While natural killer (NK) cells are implicated in apoptosis of activated hepatic stellate cells/myofibroblasts, cells of myelo-monocitic lineage secrete matrix metalloproteinases to actively degrade the fibrous scar. The focus of this review is on the current understanding of the role of different subsets of BM cells in the onset, development and resolution of liver fibrosis.

Octreotide induces caspase activation and apoptosis in human hepatoma HepG2 cells

AIM: To investigate the role of octreotide on cellular proliferation and apoptosis of human hepatoma (HepG2) cells.

METHODS: We studied cellular proliferation, apoptosis and the possible internal caspase-mediated apoptosis pathway involved, after treatment of HepG2 carcinoma cells with octreotide in comparison with the apoptosis caused by tumor necrosis factor-α (TNF-α). Activities of caspase-3, caspase-9, caspase-8 and caspase-2 were studied, while apoptosis was investigated through detection of DNA fragmentation and through identification of apoptotic cells with the annexin-V/propidium iodide flow cytometric method.

RESULTS: After an initial increase in HepG2 cellular proliferation, a significant inhibition was observed with 10^-8 mol/L octreotide, while TNF-α dose-dependently decreased proliferation. Early and late apoptosis was significantly increased with both substances. Octreotide significantly increased caspase-3, caspase-8 and caspase-2 activity. TNF-α significantly increased only caspase-2. Cellular proliferation was decreased after treatment with octreotide or TNF-α alone but, in contrast to TNF-α, octreotide decreased proliferation only at concentrations of 10^-8 mol/L, while lower concentrations increased proliferation.

CONCLUSION: Our findings are suggestive of caspase-mediated signaling pathways of octreotide antitumor activity in HepG2 cells, and indicate that measurements of serum octreotide levels may be important, at least in clinical trials, to verify optimal therapeutic drug concentrations.

An unbiased stereological study on subpopulations of rat liver macrophages and on their numerical relation with the hepatocytes and stellate cells

Studies on liver macrophages have elucidated their key roles in immunological, fibrotic and regenerative responses, and shown that macrophages are not a homogeneous population. In the rat, two sets of liver macrophages coexist, identified by ED1 and ED2 antibodies. Those sets have different quantitative responses in liver injuries and may have different tasks throughout the injury and recovery phases. Nevertheless, the total number (N), number per gram (N g(-1)) and proportion of those macrophages in relation to other liver cells has never been quantified using design-based stereology. Thus, we combined immunocytochemistry with those tools to produce an unbiased estimate of the N of ED1(+) and of ED2(+) cells. A smooth fractionator sampling scheme was applied to the liver of five male Wistar rats (3 months old), to obtain systematic uniform random sections (30 microm thick); these were immunostained with the monoclonal antibodies: ED1, a pan-macrophagic marker; and ED2, which identifies the completely differentiated macrophages, i.e. Kupffer cells. The N of ED1(+) cells was 340 x 10(6), estimated with a coefficient of error (CE) of 0.04, and that of ED2(+) cells was 283 x 10(6), with a CE of 0.05. These figures correspond to 10.7% and 8.9%, respectively, of the total liver cells. The new data constitute reference values for correlative inferences. Also, the methodological strategy, by its accuracy and precision, is valuable for future investigations on the liver cell composition in various models of disease, and especially for studying the more subtle variations that occur during the injury and recovery phases.

Isolation of rat Kupffer cells by ex vivo perfusion and their primary culture

AIM: To explore a convenient and effective method for isolation and primary culture of rat Kupffer cells (KCs) in vitro.

METHODS: Ex vivo rat liver tissue was perfused with collagenase IV and diced into small pieces. The diced tissue was digested for 30 min at 37℃and centrifuged to remove hepatocytes. KCs were then separated by means of Percoll density gradient centrifugation and selective adherence. Phagocytosis assay and immunocytochemistry for ED2 were used to identify cells isolated.

RESULTS: The average cell yield per gram of liver before plastic adherence was (2.1 ± 0.3) × 10⁶, and (1.5 ± 0.1) × 10⁶following plastic adherence. The viability of KCs isolated was higher than 92% as determined by trypan blue exclusion. The purity of KCs, identified by immunocytochemistry for ED2, was higher than 90%. Cultured KCs were functionally intact and exhibited irregular shape.

CONCLUSION: The method for isolation and culture of Kupffer cells by ex vivo perfusion is convenient, efficient and stable. Cultured Kupffer cells retain naive biological characteristics and can be used in future studies.

Role of Kupffer cells in hepatic fibrosis

Kupffer cells (KC), a kind of nonparenchymal cells and defenders in the liver, release various chemical mediators to induce liver injury, and play an important role in many pathologic changes of the liver. Hepatic fibrosis is the common pathologic process of varied chronic liver diseases, and it is also a "transfer station" for many chronic liver diseases lapsing to cirrhosis. As important influencing factors, cytokines secreted by KC are involved in the occurrence and progression of hepatic fibrosis. Therefore, lucubrating the role and mechanism of KC in the progression of hepatic fibrosis, and investigating the KC-related therapeutic strategies of anti-fibrosis have practical significances for the prevention and treatment of liver injury and the raise of patients' survival rates in clinical practice.

Relation between lipogranuloma formation and fibrosis, and the origin of brown pigments in lipogranuloma of the canine liver

BACKGROUND

In a previous study we confirmed that canine hepatic lipogranuloma, defined as lesions consisting of small round cells which contain lipid vacuoles and brown pigments in their cytoplasm, was an assembly of Kupffer cells and/or macrophages, and that the cytoplasmic brown pigments in the lesions were hemosiderin and ceroid. However, the pathogenesis of the lesion remains unclear. Kupffer cells (resident macrophages) play a key role in hepatic fibrogenesis due to the production of cytokines including TGF-beta. In the present study, we have examined 52 canine liver samples (age: newborn - 14 years; 25 males and 27 females) and investigated the correlation between lipogranuloma formation and fibrosis as well as the origin of brown pigments of lipogranulomas.

RESULTS

Lipogranulomas were detected histopathologically in 23 (44.2%) of the 52 liver samples. No significant correlation was found between the density of lipogranulomas and distribution of collagen type I/III in the liver. Pigmentation of lipogranulomas showed significant correlations with that on both hepatocytes and sinusoidal cells, indicating that pigments of lipogranuloma (hemosiderin and ceroid) might be derived from hepatocytes and Kupffer cells.

CONCLUSION

Lipogranulomas are not a contributing factor in hepatic fibrosis, but might be a potential indicator of the accumulation of iron and lipid inside the liver.

Further studies on the hepatoprotective effects ofAnoectochilus formosanus

The purpose of this study was to investigate the hepatoprotective effects of Anoectochilus formosanus effective fraction (AFEF) on chronic liver damage induced by carbon tetrachloride (CCl4) in mice. CCl4 (5%; 0.1 mL/10 g body weight) was given twice a week for 9 weeks, and mice received AFEF throughout the whole experimental period. Plasma GPT, hepatic levels of hydroxyproline and malondialdehyde were significantly lower in mice treated with AFEF compared with those treated with CCl4 only. Liver pathology in the AFEF-treated mice was also improved. RT-PCR analysis showed that AFEF treatment increased the expression of methionine adenosyltransferase 1A and decreased the expression of collagen(alpha1)(I) and transforming growth factor-beta1. These results clearly demonstrated that AFEF reduced the hepatic damage induced by CCl4 in mice.

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

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

The renin-angiotensin system in a rat model of hepatic fibrosis: evidence for a protective role of Angiotensin-(1-7)

BACKGROUND/AIMS

The circulating renin-angiotensin system (RAS) [plasma renin activity (PRA), Angiotensin (Ang) I, Ang II and Ang-(1-7)] was evaluated in a model of hepatic fibrosis in rats. To investigate the pathophysiological involvement of Ang-(1-7), animals were treated with the Ang-(1-7) Mas receptor antagonist, A-779.

METHODS

RAS components, liver function and histology were examined in male Wistar rats (220-300 g). Animals were submitted to sham-surgery or ligature of the bile duct and evaluated 1, 2, 4 and 6 weeks later. Blood samples were obtained to determine biochemical parameters and RAS components. A second group was treated with A-779 or vehicle to measure liver hydroxyproline and total transforming growth factor beta-1 (TGFbeta1).

RESULTS

PRA and Ang I were significantly elevated in rats at 4 and 6 weeks compared to sham-operated animals. Ang II and Ang-(1-7) progressively increased over the 6 weeks. Changes in RAS profile correlated with histological signs of fibrosis and deterioration in liver function. Pharmacological blockade of the Ang-(1-7) receptor aggravated liver fibrosis with a significant elevation in hydroxyproline and total TGFbeta(1).

CONCLUSIONS

Hepatic fibrosis was associated with RAS activation in our model. Our data also suggested that Ang-(1-7) played a protective role in hepatic fibrosis.

RT-PCR and immunocytochemistry studies support the presence of somatostatin, cortistatin and somatostatin receptor subtypes in rat Kupffer cells

The present study investigated the presence of somatostatin receptor subtypes (ssts) and the endogenous peptides somatostatin and cortistatin in rat Kupffer cells, since modulation of these cells by somatostatin may be important for the beneficial effect of somatostatin analogues in a selected group of hepatocellular carcinoma patients. Kupffer cells were isolated from rat liver in agreement with national and EU guidelines. RT-PCR was employed to assess the expression of somatostatin, cortistatin and ssts in Kupffer cells. Western blot analysis and immunocytochemistry were employed to assess the expression and the localization of the receptors, respectively. Quiescent Kupffer cells were found to express sst(1-4) mRNA, while immunocytochemical studies supported the presence of only the sst(3) and sst(4) receptors, which were found to be internalized. However, sst1 and sst(2A) receptors were detected by western blotting. RT-PCR and RIA measurements support the presence of both somatostatin and cortistatin. Stimulation of the cells with LPS activated the expression of the sst(2), sst(3) and sst(4) receptors. The present data provide evidence to support the presence of ssts and the endogenous neuropeptides somatostatin and CST in rat Kupffer cells. Both peptides may act in an autocrine manner to regulate sst receptor distribution. Studies are in progress in order to further characterize the role of ssts in Kupffer cells and in hepatic therapeutics.

Protective effect of verapamil on multiple hepatotoxic factors-induced liver fibrosis in rats

The purpose of the present work was to investigate the effect of verapamil on liver fibrosis induced by multiple hepatotoxic factors in rats. Male Wistar rats were divided into a normal control group, a liver fibrosis model control group, and verapamil groups with different dosages. Multiple hepatotoxic factors including carbon tetrachloride (CCl(4)), ethanol and high cholesterol were used to make the animal model of liver fibrosis. The parameters of serum l-alanine aminotransferase (ALT), liver malondialdehyde and hydroxyproline contents were measured. Samples of the liver obtained by biopsy were subjected to histological and immunohistochemical studies for the expressions of alpha-smooth muscle actin (alpha-SMA) and transforming growth factor-beta(1) (TGF-beta(1)). Results showed that verapamil induced a dose-dependent decrease of serum ALT, liver malondialdehyde and hydroxyproline compared with liver fibrosis model control. Verapamil reduced hepatocyte degeneration and necrosis, and delayed the formation of liver fibrosis. The levels of expression of alpha-SMA and TGF-beta(1) in the hepatic tissue of three of the verapamil-treated groups were significantly less than those of the liver fibrosis model control group. The results showed that verapamil acts against the formation of liver fibrosis, the mechanism might be due to a protective effect for hepatocytes and through decreasing TGF-beta(1) to block the activation of hepatic stellate cells (HSCs) and collagen gene expression.

Role of Kupffer cells in the pathogenesis of liver disease

Kupffer cells, the resident liver macrophages have long been considered as mostly scavenger cells responsible for removing particulate material from the portal circulation. However, evidence derived mostly from animal models, indicates that Kupffer cells may be implicated in the pathogenesis of various liver diseases including viral hepatitis, steatohepatitis, alcoholic liver disease, intrahepatic cholestasis, activation or rejection of the liver during liver transplantation and liver fibrosis. There is accumulating evidence, reviewed in this paper, suggesting that Kupffer cells may act both as effector cells in the destruction of hepatocytes by producing harmful soluble mediators as well as antigen presenting cells during viral infections of the liver. Moreover they may represent a significant source of chemoattractant molecules for cytotoxic CD8 and regulatory T cells. Their role in fibrosis is well established as they are one of the main sources of TGFβ1 production, which leads to the transformation of stellate cells into myofibroblasts. Whether all these variable functions in the liver are mediated by different Kupffer cell subpopulations remains to be evaluated. In this review we propose a model that demonstrates the role of Kupffer cells in the pathogenesis of liver disease.

Expression, pharmacology, and functional role of somatostatin receptor subtypes 1 and 2 in human macrophages

Somatostatin (SRIF)-14 is recognized as an important mediator between the nervous and the immune system, although the functional role of its receptors (sst(1)-sst(5)) is poorly understood in humans. In our study, we demonstrate that human macrophages, differentiated from PBMC-derived monocytes, express sst(1) and sst(2) mRNAs. sst(1) and sst(2) are mostly localized at the cell surface and display active binding sites. In particular, sst(1)/sst(2) activation results in a weak internalization of sst(1), and the sst(2) internalization appears more efficient. At the functional level, the activation of SRIF receptors by the multiligand analogs SOM230 and KE108, but not by SRIF-14 or cortistatin-14, reduces macrophage viability. Their effects are mimicked by the selective activation of sst(1) and sst(2) using CH-275 and SMS 201-995/L-779,976, respectively. Further, sst(1)- and sst(2)-mediated effects are reversed by the sst(1) antagonist SRA-880 or the sst(2) antagonist CYN 154806, respectively. CH-275, SMS 201-995, and L-779,976, but not SRIF-14, decrease mRNA expression and secretion of the MCP-1. In addition, SRIF-14, CH-275, SMS 201-995, and L-779,976 decrease IL-8 secretion, and they do not affect IL-8 mRNA expression. In contrast, SRIF-14 and sst(1)/sst(2) agonists do not affect the secretion of matrix metalloproteinase-9. Collectively, our results suggest that the SRIF system, through sst(1) and sst(2), exerts mainly an immunosuppressive effect in human macrophages and may, therefore, represent a therapeutic window that can be exploited for the development of new strategies in pharmacological therapy of inflammation.

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

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

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

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

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

The hepatoprotective activity of kinsenoside fromAnoectochilus formosanus

Carbon tetrachloride (CCl(4)) causes chronic hepatitis, featuring an increase in hepatic hydroxyproline, spleen weight and serum GPT levels and a decrease in plasma albumin levels. Crude extracts of fresh whole plants of Anoectochilus formosanus showed inhibition of chronic hepatitis induced by CCl(4) in mice. Bioactivity-guided fractionation and spectroscopic analysis revealed that kinsenoside was the most active compound. In an in vitro study, the LD(50) values for H(2)O(2)-induced cytotoxicity in BALB/c normal liver cells were significantly higher after kinsenoside pretreatment than after vehicle alone, further confirming that kinsenoside shows significant antihepatotoxic activity.