Expression of cytokines (TNF-alpha, IL-1alpha, and IL-2) in chronic hepatitis C: comparative hybridocytochemical and immunocytochemical study in children and adult patients

Exploring the Impact of Different Inflammatory Cytokines on Hepatitis C Virus Infection

Hepatitis C virus (HCV) infection is a global health concern affecting millions worldwide. Chronic HCV infection often leads to liver inflammation and can progress to cirrhosis and hepatocellular carcinoma. Inflammatory cytokines are crucial in modulating the immune response during HCV infection. This review aims to investigate the impact of different inflammatory cytokines on HCV infection and associated immune responses. This review was conducted to identify relevant studies on the interplay between inflammatory cytokines and HCV infection. The analysis focused on the effects of key inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 (IL-1), and interferon-gamma (IFN-γ), on HCV replication, immune cell activation, and liver inflammation. The findings reveal that these inflammatory cytokines can significantly influence HCV infection and the subsequent immune response. TNF-α, IL-6, and IL-1 have been shown to enhance HCV replication, while IFN-γ exerts antiviral effects by inhibiting viral replication and promoting immune cell-mediated clearance of infected hepatocytes. Moreover, these cytokines contribute to the recruitment and activation of immune cells, such as natural killer cells, T cells, and macrophages, which play critical roles in controlling HCV infection. Understanding the precise mechanisms by which inflammatory cytokines impact HCV infection is crucial for developing more targeted therapeutic strategies. Modulating the levels or activity of specific cytokines may provide opportunities to attenuate HCV replication, reduce liver inflammation, and improve treatment outcomes. In conclusion, this review highlights the significance of inflammatory cytokines in influencing HCV infection and associated immune responses.

Transplacental infection by bovine alphaherpesvirus type 1 induces protein expression of COX-2, iNOS and inflammatory cytokines in fetal lungs and placentas

Bovine alphaherpesvirus type 1 (BoAHV-1) is associated with respiratory and reproductive syndromes. Until present the immunologic mechanisms involved in BoAHV-1 abortion are partially known. We studied key elements of the innate immune response in the placentas and fetal lungs from cattle experimentally-inoculated with BoAHV-1. These tissues were analyzed by histopathology. Furthermore, virus identification was performed by qPCR and the expression of the inflammatory cytokines such as tumor necrosis factor-alpha, interleukin 1-alpha and inflammatory mediators like inducible nitric oxide synthase and cyclooxeganse-2 was evaluated by immunohistochemistry. The viral transplacental infection was confirmed by the detection of BoAHV-1 by qPCR in the placenta and fetal organs, which revealed mild inflammatory lesions. Inducible nitric oxide synthase immunolabelling was high in the lungs of infected fetuses and placentas, as well as for tumor necrosis factor-alpha in the pulmonary parenchyma and cyclooxeganse-2 in fetal annexes. However, the expression of interleukin 1-alpha was weak in these organs. To our knowledge, this is the first study that provides strong evidence of an early immune response to BoAHV-1 infection in the conceptus. Advances in the knowledge of the complex immunological interactions at the feto-maternal unit during BoAHV-1 infection are needed to clarify the pathogenesis of abortion.

Cyclosporine Ameliorates Silica-Induced Autoimmune Hepatitis in Rat Model by Altering the Expression of Toll-Like Receptor-4, Interleukin-2, and Tumor Necrosis Factor-α

BACKGROUND

Autoimmune hepatitis (AIH) is an inflammatory liver disease that is characterized histologically by interface hepatitis, biochemically by elevated transaminase levels, and serologically by the presence of autoantibodies. Toll-like receptor (TLR)-4 is a TLR family member that, upon activation in hepatocytes, initiates a cascade of events. Interleukin-2 (IL-2) and tumour necrosis factor α (TNF-α) are potent inflammatory cytokines secreted in AIH, playing an important role in the early development of inflammation and hepatocyte damage.

OBJECTIVES

This study examined the role of cyclosporine in AIH and illustrated its actions on altered hepatic function in the silica-induced AIH model.

METHODS

AIH was induced in Wistar rats using sodium silicate. The rats were divided into four groups: the control group, silica-AIH group, cyclosporine-treated group, and prevention group. TLR-4 and IL-2 mRNA expressions in liver tissues were tested by RTPCR.

RESULTS

AIH was associated with up-regulation of liver enzymes, IL-2 and TLR-4 gene expression, while cyclosporine significantly down-regulated the expression of both. The relative quantity of TLR-4 mRNA was 1±0, 13.57±1.91, 4±0.38, and 2±0 in control, AIH, cyclosporine, and prevention groups, respectively (p<0.001). Also, the relative quantity of IL-2 mRNA was 1±0, 14.79±1.42, 7.07±0.96, and 3.4±0.55 in control, AIH, cyclosporine, and prevention groups, respectively (p<0.001). Additionally, immunohistochemical staining for TNF-α in liver sections was increased in the silica-AIH group but was found to decrease in the cyclosporine-treated and prevention groups.

CONCLUSION

This study advocates the therapeutic role of cyclosporine in treating immune-mediated hepatic diseases. Cyclosporine improves histological alterations in the liver and inhibits the production of proinflammatory cytokines.

Hepatitis C Core Protein Induces a Genotype-Specific Susceptibility of Hepatocytes to TNF-Induced Death In Vitro and In Vivo

Hepatitis C virus (HCV) core protein is a multifunctional protein that is involved in the proliferation, inflammation, and apoptosis mechanism of hepatocytes. HCV core protein genetic variability has been implicated in various outcomes of HCV pathology and treatment. In the present study, we aimed to analyze the role of the HCV core protein in tumor necrosis factor α (TNFα)-induced death under the viewpoint of HCV genetic variability. Immortalized hepatocytes (IHH), and not the Huh 7.5 hepatoma cell line, stably expressing HCV subtype 4a and HCV subtype 4f core proteins showed that only the HCV 4a core protein could increase sensitivity to TNFα-induced death. Development of two transgenic mice expressing the two different core proteins under the liver-specific promoter of transthyretin (TTR) allowed for the in vivo assessment of the role of the core in TNFα-induced death. Using the TNFα-dependent model of lipopolysaccharide/D-galactosamine (LPS/Dgal), we were able to recapitulate the in vitro results in IHH cells in vivo. Transgenic mice expressing the HCV 4a core protein were more susceptible to the LPS/Dgal model, while mice expressing the HCV 4f core protein had the same susceptibility as their littermate controls. Transcriptome analysis in liver biopsies from these transgenic mice gave insights into HCV core molecular pathogenesis while linking HCV core protein genetic variability to differential pathology in vivo.

Host immune response in chronic hepatitis C infection: involvement of cytokines and inflammasomes

Chronic liver disease is a major health issue worldwide and chronic hepatitis C (CHC) is associated with an increased risk of cirrhosis and hepatocellular carcinoma (HCC). There is evidence that the hepatitis C virus (HCV) infection is correlated with immune senescence by way of immune activation and chronic inflammation, which lead to increased metabolic and cardiovascular risk, as well as progressive liver damage. Both the innate and adaptive immunity are firmly tied to the prognosis of an infection with HCV and its response to antiviral therapy. HCV is therefore associated with increased pro-inflammatory status, heightened production of cytokines, prolonged systemic inflammation, as well as increased morbidity and mortality, mainly due to the progression of hepatic fibrosis and HCC, but also secondary to cardiovascular diseases. Viral hepatic pathology is increasingly considered a disease that is no longer merely limited to the liver, but one with multiple metabolic consequences. Numerous in vitro studies, using experimental models of acute or chronic inflammation of the liver, has brought new information on immunopathological mechanisms resulting from viral infections and have highlighted the importance of involving complex structures, inflammasomes complex, in these mechanisms, in addition to the involvement of numerous proinflammatory cytokines. Beyond obtaining a sustained viral response and halting the aforementioned hepatic fibrosis, the current therapeutic “treat-to-target” strategies are presently focused on immune-mediated and metabolic disorders, to improve the quality of life and long-term prognosis of CHC patients.

Chlorogenic acid, quercetin, coenzyme Q10 and silymarin modulate Keap1-Nrf2/heme oxygenase-1 signaling in thioacetamide-induced acute liver toxicity

BACKGROUND AND AIMS

The normal functioning of Kelch-like ECH-associated protein-1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) complex is necessary for the cellular protection against oxidative stress. We investigated the effect of chlorogenic acid (CGA), quercetin (Qt), coenzyme Q10 (Q10) and silymarin on the expression of Keap1/Nrf2 complex and its downstream target; heme oxygenase-1 (HO-1) as well as inflammation and apoptosis in an acute liver toxicity model induced by thioacetamide (TAA).

MAIN METHODS

Wistar rats were divided into 13 groups: Control, silymarin, CGA, Qt, Q10, TAA (single dose 50 mg/kg, i.p.), TAA + silymarin (400 mg/kg, p.o.), TAA + CGA (100 & 200 mg/kg, p.o.), TAA + Qt (200 &300 mg/kg, p.o.) and TAA+ Q10 (30&50 mg/kg, p.o.) and treated for 8 days.

KEY FINDINGS

The results showed improved liver functions and hepatic tissue integrity in all tested doses of TAA + silymarin, TAA + CGA, TAA + Qt and TAA + Q10 groups compared to the TAA group. Furthermore, these groups showed significantly lower ROS, malondialdehyde and nitric oxide levels but higher glutathione content and superoxide dismutase activity compared to the TAA group, p < 0.05. In these groups, Keap1 expression was significantly decreased while Nrf2 expression and HO-1 activity were increased. In addition, the number of apoptotic cells and the expression level of TNF-α in the liver tissues were significantly decreased compared to the TAA group.

SIGNIFICANCE

CGA, Qt, Q10 and silymarin protect against TAA-induced acute liver toxicity via antioxidant, anti-inflammatory, anti-apoptotic activities and regulating Keap1-Nrf2/HO-1 expression.

Impact of Washingtonia robusta Leaves on Gamma Irradiation-Induced Hepatotoxicity in Rats and Correlation with STING Pathway and Phenolic Composition

Exposure to ionizing radiation usually results in cellular oxidative damage and may induce liver toxicity. The efficiency of the ethanol extracts of Washingtonia filifera (EWF) and Washingtonia robusta (EWR) leaves in alleviating γ-radiation-induced oxidative hepatotoxicity was herein explored. Proximate and macronutrient composition of the leaves was determined to establish reliable quality control criteria. Colorimetric estimation of total phenolic (TPC) and flavonoid (TFC) contents revealed their occurrence in larger amounts in EWR. In vitro evaluation of the antioxidant capacity by 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) assays confirmed higher efficiency of EWR designating a close correlation with phenolic composition. Four phenolics, viz., naringenin, kaempferol, quercetin, and gallic acid, were isolated from EWR. In vivo assessment of the extracts' antioxidant potential was performed on γ-irradiated (7.5 Gy) female rats. EWR was found more efficient in restoring the elevated liver index, ALT, albumin, cholesterol, and reactive oxygen species (ROS) levels. Both extracts ameliorated the increase in the stimulator of interferon gene (STING) expression. Bioactivity was confirmed by immuno-histochemical examination of inflammatory and apoptotic biomarkers (TNF-α, IL-6 and caspase-3) and histopathological architecture. In addition, the interactions of the isolated compounds with STING were assessed in silico by molecular docking. Therefore, Washingtonia robusta leaves might be suggested as a valuable nutritional supplement to alleviate radiotherapy-induced hepatotoxicity.

Cytokines and serum amyloid A in the pathogenesis of hepatitis C virus infection

Expression of the acute phase protein serum amyloid A (SAA) is dependent on the release of the pro-inflammatory cytokines IL-1, IL-6 and TNF-α during infection and inflammation. Hepatitis C virus (HCV) upregulates SAA-inducing cytokines. In line with this, a segment of chronically infected individuals display increased circulating levels of SAA. SAA has even been proposed to be a potential biomarker to evaluate treatment efficiency and the course of disease. SAA possesses antiviral activity against HCV via direct interaction with the viral particle, but might also divert infectivity through its function as an apolipoprotein. On the other hand, SAA shares inflammatory and angiogenic activity with chemotactic cytokines by activating the G protein-coupled receptor, formyl peptide receptor 2. These latter properties might promote chronic inflammation and hepatic injury. Indeed, up to 80 % of infected individuals develop chronic disease because they cannot completely clear the infection, due to diversion of the immune response. In this review, we summarize the interconnection between SAA and cytokines in the context of HCV infection and highlight the dual role SAA could play in this disease. Nevertheless, more research is needed to establish whether the balance between those opposing activities can be tilted in favor of the host defense.

Glycine protects partial liver grafts from Kupffer cell-dependent ischemia-reperfusion injury without negative effect on regeneration

Donor preconditioning with glycine prevents Kupffer cell-dependent reperfusion injury to liver grafts. Partial liver grafts need to regenerate and grow in size after transplantation; however, glycine inactivates Kupffer cells, which are important for hepatic regeneration. Thus, this study was designed to evaluate the impact of donor preconditioning with glycine after partial liver transplantation (pLTx). PLTx was performed in 28 female Sprague-Dawley rats. Glycine (1.5 ml, 300 mM; i.v.) was given to 14 live donors before organ procurement. Liver enzymes and histology were investigated 8 h after reperfusion to index liver injury and leukocyte infiltration. Hepatic microperfusion and leukocyte-endothelium interaction were assessed using the in vivo fluorescence microscopy method. Ki-67 and TNF-α were detected by immunohistochemistry for regeneration and Kupffer cell activation. Glycine significantly increased survival from 0% in controls to 40%, while both liver enzyme levels and necrosis were decreased to about 50% of controls (p < 0.05). Sinusoidal blood flow increased by 40-80%, while leukocyte-endothelium interaction decreased to 30% of control values (p < 0.05). While Kupffer cell-derived TNF-α decreased to 70% of controls, there was no difference between groups in Ki-67 expression. Data presented here clearly demonstrate that glycine protects partial liver grafts from reperfusion injury without effects on regeneration.

The role of systemic inflammation in the pathogenesis of insulin resistance and metabolic syndrome in patients with chronic hepatitis C

The systemic inflammatory response plays a key role in the development of atherosclerosis, insulin resistance (IR) and diabetes mellitus 2-type (diabetes mellitus). IR in patients with chronic hepatitis C (CHC) is considered as a possible factor in the progression of fibrosis, a predictor of the development of DM T2 and a component of the metabolic syndrome. The use of biomarkers of non-specific inflammation can be a valuable tool for assessing the risks of IR and cardiovascular diseases in patients with chronic hepatitis C. Aim of the study. To determine the role of nonspecific inflammation in the formation of IR and metabolic syndrome in patients with chronic hepatitis C. Materials and methods. The study included 205 patients with CHC aged 18 to 69 years. Patients with CHC are randomized into two groups depending on the presence of IR: group 1 - patients with a HOMA index ≥2.77, which corresponded to IR (n=110); group 2 (n=95). The levels of serum iron, C-reactive protein (CRP), serum ferritin and adipose tissue hormones [leptin, resistin, adiponectin and tumor necrosis factor-α (TNF-α)] were additionally investigated. Results. At all stages of development of IR, nonspecific inflammation was detected (according to ferritin, CRP and serum iron), increasing with increasing HOMA index [Homeostasis Model of Assessment - Insulin Resistance (HOMA-IR)] (Matthews D., 1985), metabolic syndrome and its components. In the analysis of indicators in patients with chronic hepatitis C with a body mass index

IL-1α correlates with severity of hepatitis C virus-related liver diseases

BACKGROUND AND AIMS

Immunoregulatory cytokines influence the persistence of hepatitis C virus (HCV) chronic infection and the extent of liver damage. Interleukin-1 (IL-1) plays an important role in the inflammatory process. Some studies have demonstrated that IL-1α production was impaired in patients with chronic infections of HCV, implying that IL-1α may play a role in viral clearance. The aim of this study was to evaluate the serum level of proinflammatory cytokine IL-1α in patients with chronic hepatitis C (CHC).

METHODS

This study was performed on 20 CHC patients with cirrhosis in (Group I), 20 CHC patients without cirrhosis in (Group II), 20 hepatocellular carcinoma (HCC) patients with positive anti-HCV in (Group III), and 10 healthy subjects as a control group. Serum levels of IL-1α were measured by enzyme-linked immunoassay technique.

RESULTS

IL-1α had the highest mean concentration in the HCC group and then in the group of CHC with cirrhosis compared to the group of CHC without cirrhosis. Also, it was higher in all studied groups than in the control group (P<0.001). Statistical analysis showed that IL-1α was positively correlated with bilirubin (P≤0.001), alanine aminotransferase (P=0.006), aspartate aminotransferase (P=0.001), and viral load (P=0.001) but it was negatively correlated with albumin (P≤0.001) and Hb (P≤0.001), and was not significantly correlated with other parameters (age, international normalized ratio, urea, creatinine, white blood cells, and platelet count).

CONCLUSION

Serum level of IL-1α was elevated in patients with CHC and its related liver diseases (liver cirrhosis and HCC) and can be used as an important parameter of inflammatory activity and for fibrosis evaluation in patients with chronic liver disease.

Lobohedleolide suppresses hepatitis C virus replication via JNK/c-Jun-C/EBP-mediated down-regulation of cyclooxygenase-2 expression

Hepatitis C virus (HCV) chronically infects 2–3% people of the global population, which leads to liver cirrhosis and hepatocellular carcinoma. Drug resistance remains a serious problem that limits the effectiveness of US Food and Drug Administration (FDA)-approved direct-acting antiviral (DAA) drugs against HCV proteins. The objective of our study was to discover new antivirals from natural products to supplement current therapeutics. We demonstrated that lobohedleolide, isolated from the Formosan soft coral Lobophytum crassum, significantly reduced HCV replication in replicon cells and JFH-1 infection system, with EC₅₀ values of 10 ± 0.56 and 22 ± 0.75 μM, respectively, at non-toxic concentrations. We further observed that the inhibitory effect of lobohedleolide on HCV replication is due to suppression of HCV-induced cyclooxygenase-2 (COX-2) expression. Based on deletion-mutant analysis of the COX-2 promoter, we identified CCAAT/enhancer-binding protein (C/EBP) as a key transcription factor for the down-regulation of COX-2 by lobohedleolide, through which lobohedleolide decreased the phosphorylation of c-Jun NH2-terminal protein kinase and c-Jun to suppress HCV-induced C/EBP expression. The combination treatment of lobohedleolide with clinically used HCV drugs synergistically reduced HCV RNA replication, indicating that lobohedleolide exhibited a high biomedical potential to be used as a supplementary therapeutic agent to control HCV infection.

Roles of hepatic stellate cells in liver inflammation: a new perspective

Connected with the intestinal tract through the portal circulation, liver sinusoids function as the first line of defense against extrahepatic stimuli such as bacterial products and other toxic substances. Hepatic stellate cells (HSCs) are pericytes residing in the perisinusoidal space, between sinusoidal endothelial cells and hepatocytes, store vitamin A, and regulate sinusoidal circulation. Following chronic hepatitis, HSCs actively produce extracellular matrices and cause liver fibrosis. In spite of their close position to the liver sinusoids, however, whether HSCs contribute to liver inflammation has remained elusive. Evidence now accumulates to suggest that HSCs actively take part in the regulation of various forms of liver inflammation. Upon inflammatory stimuli from the sinusoids, HSCs produce various inflammatory molecules and interact with other liver cells, thereby recruiting and then activating infiltrating leukocytes and ultimately causing hepatocyte death. On the other hand, HSCs also exert hepatoprotective effects through inhibition of cytokine and chemokine production or induction of immunosuppressive cell population. HSCs therefore integrate cytokine-mediated inflammatory responses in the sinusoids and relay them to the liver parenchyma, either amplifying liver inflammation or suppressing parenchymal damage through immunoregulatory signaling depending on the context.

Significant hepatic expression of IL-2 and IL-8 in biliary atresia compared with other neonatal cholestatic disorders

OBJECTIVES

Although the exact etiology of biliary atresia (BA) is still elusive, inflammation plays a key role. Release of proinflammatory cytokines from activated immune cells perpetuates the injury and causes biliary destruction. We aimed to study interleukin (IL)-2 and IL-8 expression in liver tissue of BA patients compared with other neonatal cholestatic disorders.

METHODS

The study included 59 infants with neonatal cholestasis in two groups; BA group (n=31) and non-BA group (n=28) with cholestatic disorders other than BA as controls. Demographic, clinical, laboratory, and histopathological parameters were collected. IL-2 and IL-8 immunostaining was performed. Immunostaining in portal cellular infiltrate was scored as positive or negative and expressed as the mean cell count in three portal tracts.

RESULTS

The mean value of IL-2 and IL-8 positive inflammatory cells was significantly higher in BA than in non-BA group (P-values of 0.004 and 0.002 respectively). IL-2 correlated significantly with IL-8 immunostaining in both BA and non-BA group (P<0.0001 for both). Furthermore, both cytokines in both groups correlated significantly with inflammatory activity in liver biopsy while there was no significant correlation with the other studied parameters. Yet, there was a trend of increased expression of IL-2 and IL-8 with increasing stage of fibrosis in BA group. This trend was not observed in non-BA group.

CONCLUSION

The significantly higher expression of IL-2 and IL-8 in patients with BA compared to non-BA suggests a potential role for these cytokines in the pathogenesis in therapy of this devastating neonatal hepatic disorder.

Role of fibrogenic and inflammatory cytokines in HCV-induced fibrosis

HCV is one of the main causative agents of liver fibrosis and hepatocellular carcinoma. Liver inflammation resulting from HCV infection triggers fibrosis. In HCV-related fibrosis, differentiated hepatic stellate cells (HSCs) known as myofibroblasts participate in the fibrogenic and inflammatory response. TGF-β1 and CTGF, released from these HSCs, have been implicated as master cytokines mediating HCV induced hepatic fibrosis. PDGF is another potent mitogen, which facilitates the progression of liver fibrosis by enhancing the proliferation and migration of HSCs. In addition to these major cytokines, the release of TNF-α, IL-6, IL-1b and IL-10 by immune cells also promotes the effect of HCV induced fibrosis. Targeting these cytokines may offer the potential for treatments to prevent or cure fibrosis.

Interactions between Myc and Mediators of Inflammation in Chronic Liver Diseases

Most chronic liver diseases (CLDs) are characterized by inflammatory processes with aberrant expressions of various pro- and anti-inflammatory mediators in the liver. These mediators are the driving force of many inflammatory liver disorders, which often result in fibrosis, cirrhosis, and liver tumorigenesis. c-Myc is involved in many cellular events such as cell growth, proliferation, and differentiation. c-Myc upregulates IL-8, IL-10, TNF-α, and TGF-β, while IL-1, IL-2, IL-4, TNF-α, and TGF-β promote c-Myc expression. Their interactions play a central role in fibrosis, cirrhosis, and liver cancer. Molecular interference of their interactions offers possible therapeutic potential for CLDs. In this review, current knowledge of the molecular interactions between c-Myc and various well known inflammatory mediators is discussed.

Chronic HCV infection and inflammation: Clinical impact on hepatic and extra-hepatic manifestations

The liver has a central role in regulating inflammation by its capacity to secrete a number of proteins that control both local and systemic inflammatory responses. Chronic inflammation or an exaggerated inflammatory response can produce detrimental effects on target organs. Chronic hepatitis C virus (HCV) infection causes liver inflammation by complex and not yet well-understood molecular pathways, including direct viral effects and indirect mechanisms involving cytokine pathways, oxidative stress and steatosis induction. An increasing body of evidence recognizes the inflammatory response in chronic hepatitis C as pathogenically linked to the development of both liver-limited injury (fibrosis, cirrhosis and hepatocellular carcinoma) and extrahepatic HCV-related diseases (lymphoproliferative disease, atherosclerosis, cardiovascular and brain disease). Defining the complex mechanisms of HCV-induced inflammation could be crucial to determine the global impact of infection, to estimate progression of the disease, and to explore novel therapeutic approaches to avert HCV-related diseases. This review focuses on HCV-related clinical conditions as a result of chronic liver and systemic inflammatory states.

Hepatitis C virus infection induces inflammatory cytokines and chemokines mediated by the cross talk between hepatocytes and stellate cells

Inflammatory cytokines and chemokines play important roles in inflammation during viral infection. Hepatitis C virus (HCV) is a hepatotropic RNA virus that is closely associated with chronic liver inflammation, fibrosis, and hepatocellular carcinoma. During the progression of HCV-related diseases, hepatic stellate cells (HSCs) contribute to the inflammatory response triggered by HCV infection. However, the underlying molecular mechanisms that mediate HSC-induced chronic inflammation during HCV infection are not fully understood. By coculturing HSCs with HCV-infected hepatocytes in vitro, we found that HSCs stimulated HCV-infected hepatocytes, leading to the expression of proinflammatory cytokines and chemokines such as interleukin-6 (IL-6), IL-8, macrophage inflammatory protein 1α (MIP-1α), and MIP-1β. Moreover, we found that this effect was mediated by IL-1α, which was secreted by HSCs. HCV infection enhanced production of CCAAT/enhancer binding protein (C/EBP) β mRNA, and HSC-dependent IL-1α production contributed to the stimulation of C/EBPβ target cytokines and chemokines in HCV-infected hepatocytes. Consistent with this result, knockdown of mRNA for C/EBPβ in HCV-infected hepatocytes resulted in decreased production of cytokines and chemokines after the addition of HSC conditioned medium. Induction of cytokines and chemokines in hepatocytes by the HSC conditioned medium required a yet to be identified postentry event during productive HCV infection. The cross talk between HSCs and HCV-infected hepatocytes is a key feature of inflammation-mediated, HCV-related diseases.

Impact of HCV genetic differences on pathobiology of disease

Multiple HCV genotypes have been isolated worldwide. Genotype seems to be involved in the main pathological aspects of HCV infection. Insulin resistance, steatosis and progression toward cirrhosis, fibrosis and hepatocellular carcinoma establish and develop following genotype-specific mechanisms. Moreover genotype influences pharmacological treatment in term of dose and duration. Pathways involved in cell proliferation, apoptosis, lipid metabolism, insulin and interferon signaling are impaired to a different extent among genotypes, leading to distinct pathological settings. Genotype 1 is associated with a more aggressive disease with increased insulin resistance, worst response to therapy, higher risk of cirrhosis and hepatocellular carcinoma development, while genotype 3 is associated with increased steatosis and fibrosis. The identification and characterization of HCV types and subtypes provides insight into the different outcome of HCV infection and responsiveness to therapy. In the present article, we focused on the pathogenicity of HCV genotypes and their effect on disease progression and treatment.

Green tea extract ameliorates reperfusion injury to rat livers after warm ischemia in a dose-dependent manner

SCOPE

Polyphenolic constituents of green tea (Camellia sinensis) have been shown to be potent scavengers of reactive oxygen species (ROS). Thus, this study was designed to assess its effects after liver ischemia-reperfusion.

METHODS AND RESULTS

Fasted Sprague-Dawley rats were gavaged with different concentrations of green tea extract (GTE) 2 h before 90 min of warm ischemia of the left lateral liver lobe (30% of liver). Controls were given the same volume of Ringer's solution. A preparation of pentobarbital sodium (intraperitoneal) and ketamine (intramuscular) was used for anesthesia. After reperfusion, transaminases, liver histology, hepatic microcirculation, and both phagocytosis of latex bead particles as well as the expression of tumor necrosis alpha (TNF-α) to index cellular activation were investigated. Furthermore, the expression of superoxide dismutase (Mn-SOD) was assessed. After 90 min of warm ischemia aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) increased dramatically to 1946 ± 272/3244 ± 757 U/L, 1680 ± 134/2080 ± 379 U/L, and 7857 ± 1851/2036 ± 1193 U/L at 2/6 h, respectively. GTE (200 mg/kgbody weight) significantly prevented this increase in a dose-dependent manner by 21-51% at 2 h and 29-34% at 6 h, respectively. Histology confirmed the protective effects while both TNF-α expression and phagocytosis of latex beads by Kupffer cells (KCs) were significantly reduced. GTE intake significantly increased the expression of manganese superoxide dismutase. In vivo microscopy revealed improved acinar and sinusoidal perfusion after GTE.

CONCLUSION

Preconditioning with a single oral dose of GTE ameliorates ischemia-reperfusion injury in liver. Decreased cellular activation and improved microcirculation are the proposed mechanisms.

HCV synergizes with body weight in the promotion of insulin resistance

Hepatitis C virus (HCV) infection appears to contribute to the development of insulin resistance (IR). Among the multiple determinants of IR, body mass index (BMI) is the most important. We investigated the contribution of HCV to BMI-associated IR using a transgenic mouse model expressing HCV core protein. Eight transgenic and five nontransgenic littermate controls were evaluated. Glucose and insulin tolerance tests (ITT) were performed on two separate occasions. Multivariate linear mixed modelling was used to evaluate and compare the effect of weight on IR between HCV core transgenic and nontransgenic controls. There were no statistically significant differences in glucose or ITT (P = 0.58 and P = 0.59, respectively) between the two groups, and no difference in median weights between transgenic and control mice (P = 0.11). However, there was greater variance in the distributions of Tg when compared to nontransgenic mice for both glucose and insulin tolerance. When evaluating this closely, a differential contribution of weight to IR curves between these groups was noted (P = 0.05). Among nontransgenic mice, IR curves for mice of different weights were comparable, however, for transgenic mice, higher weights resulted in larger levels of IR curves with slower decay. In all animals, steatosis was absent or minimal. We conclude that weight has a greater effect on IR in HCV core expressing transgenic mice than littermate controls. HCV therefore synergizes with weight in the promotion of IR. Steatosis was not a prerequisite for the development of IR, implying that HCV's effects on IR may be independent of steatosis.

Immunohistochemical and hybridocytochemical study on ghrelin signalling in the rat seminiferous epithelium

The results of presented study demonstrate expression of ghrelin, its functional receptor GHSR-1a and their genes in spermatogenic cells of rat testis suggesting their functioning within seminiferous epithelium. The immunohistochemical and hybrydocytochemical expression, of proteins and transcripts, was estimated taking into account the cycle of seminiferous epithelium and phases of spermatogenesis. Both transcripts and ghrelin was found to show nuclear expression and scarcely cytoplasmic. Expression of genes for ghrelin and GHSR-1a was shown in early spermatocytes and round spermatids representing transcriptional phases of meiosis and spermiogenesis. Ghrelin was evidenced to show nuclear expression in two stage-specific windows, in late spermatogonia, in spermatocytes up to early pachytenes, and again in spermatids of acrosome and early maturation phase of spermiogenesis. In late pachytenes, secondary spermatocytes, round spermatids, maturing spermatids and spermatozoa the reaction is lacking. With two types of antibodies against the GHSR-1a used the two different patterns of immunostaining was evidenced suggesting two isoforms of GHSR-1a. The first evidenced GHSR-1a in cytoplasm of spermatocytes, cell membrane and acrosomes of spermatids, Sertoli cell processes and heads of spermatozoa. With second type of antibodies the immunostaining marks all steps of evolution of acrosome in spermatids. It is believed that site of ghrelin expression in seminiferous epithelium may indicate its role in local regulations, not excepting the intracellular signalling. Immunostaining pattern for GHSR-1a seems to suggest both its participation in the cross-talk among the cells and also process of furnishing gametes with GHSR-1a for its response to ghrelin in seminal plasma or female reproductive tract.

Compound Astragalus and Salvia miltiorrhiza Extract exerts anti-fibrosis by mediating TGF-beta/Smad signaling in myofibroblasts

Previous studies showed that Compound Astragalus and Salvia miltiorrhiza Extract (CASE) has a protective effect against liver fibrosis. We hypothesized that CASE exerts the anti-fibrosis effect by mediating transforming growth factor-beta (TGF-beta)/Smad signaling pathway. To test this hypothesis, we induced fibrosis in rats by twice weekly injections of carbon tetrachloride (CCl(4)) and Smad2 phosphorylation was measured by immunohistochemical method; protein expression in myofibroblasts (MFBs) induced by TGF-beta1 was analyzed by western blotting and plasminogen activator inhibitor type 1 (PAI-1) transcriptional activity in MFBs was evaluated. The present study showed that, in vivo, CASE has protective effects against liver fibrosis in rats generated by CCl(4), and that CASE inhibits Smad2 phosphorylation at C-terminal region and expression of alpha-smooth muscle actin (alpha-SMA). Our experiment further demonstrated that, in vitro, (1) CASE inhibits TGF-beta(1)-dependent Smad2 phosphorylation at C-terminal region and Smad2 and Smad3 phosphorylation at linker region in MFBs in a dose-dependent manner; (2) CASE decreases the level of Smad 2/3/4 complex in MFBs induced by TGF-beta(1) in a dose-dependent manner; (3) CASE inhibits PAI-1 transcriptional activity in MFBs induced by TGF-beta(1) in a dose-dependent manner; and (4) CASE markedly decreases c-Jun N-terminal kinase (JNK) phosphorylation in MFBs induced by TGF-beta(1). Our results suggest that CASE's anti-fibrosis effect in chronically injured liver was exerted by inhibiting TGF-beta/Smads signal transduction.

Overexpression of B cell-activating factor of TNF family (BAFF) is associated with Helicobacter pylori-independent growth of gastric diffuse large B-cell lymphoma with histologic evidence of MALT lymphoma

We have recently demonstrated that nuclear expression of BCL10 predicts Helicobacter pylori (HP) independence of early-stage gastric diffuse large B-cell lymphoma (DLBCL) with histologic evidence of mucosa-associated lymphoid tissue (MALT). In this study, we examined the role of B cell-activating factor of TNF family (BAFF) in mediating BCL10 nuclear translocation and HP independence of gastric DLBCL (MALT). We used immunohistochemistry and immunoblotting to measure the expression of BAFF, pAKT, BCL3, BCL10, and NF-kappaB. Transactivity of NF-kappaB was measured by electromobility shift assay. In lymphoma samples from 26 patients with gastric DLBCL (MALT), we detected aberrant expression of BAFF in 7 of 10 (70%) HP-independent and in 3 of 16 (18.8%) HP-dependent cases (P = .015). BAFF overexpression was associated with pAKT expression (P = .032), and nuclear expression of BCL3 (P = .014), BCL10 (P = .015), and NF-kappaB (P = .004). In B-cell lymphoma Pfeiffer cells, BAFF activated NF-kappaB and AKT; the activated NF-kappaB up-regulated BCL10, and the activated AKT caused formation of BCL10/BCL3 complexes that translocated to the nucleus. Inhibition of AKT by LY294002 (a PI3K inhibitor) blocked BCL10 nuclear translocation, NF-kappaB transactivity, and BAFF expression. Our results indicate that autocrine BAFF signal transduction pathways may contribute to HP-independent growth of gastric DLBCL (MALT).

Obesity and steatosis influence serum and hepatic inflammatory markers in chronic hepatitis C

Obesity and fatty liver are commonly observed among patients with chronic hepatitis C virus (HCV) and are risk factors for increased hepatic fibrosis. Obesity is accompanied by a low-grade, chronic inflammatory response that may contribute to pathogenesis of obesity-related comorbidities. To assess whether obesity and steatosis potentiate expression of inflammatory markers in chronic HCV, serum protein and hepatic messenger RNA (mRNA) levels of c-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) were measured in 171 patients with chronic HCV. The relationships of body mass index, steatosis, histological features of inflammation and fibrosis with serum and hepatic levels of these factors were determined. In comparison with lean patients, overweight and obese subjects had increased circulating (P < 0.001) and hepatic (P = 0.003) CRP, and there was a significant correlation between serum protein and hepatic CRP mRNA levels (r(s)= 0.51, P < 0.001). Obesity (P = 0.001) and steatosis (P < 0.001) were associated with increased circulating but not hepatic IL-6, and a weak correlation was seen between serum protein and hepatic IL-6 mRNA levels (r(s)= 0.29, P = 0.003). An independent relationship was seen between hepatic TNF-alpha mRNA levels and higher total inflammatory score (P < 0.001) and stage of fibrosis (P = 0.037). Subjects with HCV genotype 3 had lower hepatic TNF-alpha mRNA levels compared with subjects with genotype 1 (P = 0.017), but there was no relationship between serum TNF-alpha protein and hepatic TNF-alpha mRNA levels.

CONCLUSION

In patients with chronic HCV, obesity and steatosis are associated with increased expression of selected inflammatory markers; however, circulating levels of IL-6 and TNF-alpha do not reflect hepatic expression. Hepatic TNF-alpha was associated with both increased inflammatory activity and hepatic fibrosis, providing support for the key role of this pro-inflammatory cytokine in liver injury in chronic HCV.

Taurine protects from liver injury after warm ischemia in rats: the role of kupffer cells

BACKGROUND/AIMS

Warm ischemia to liver with subsequent Kupffer cell-dependent pathology is associated with many clinical conditions. Taurine prevents Kupffer cell activation and improves graft survival after experimental cold ischemia and liver transplantation. Thus this study was designed to assess its effects after warm hepatic ischemia.

METHODS

The left liver lobe of female Sprague-Dawley rats (170-210 g) underwent 60 min of warm ischemia. Animals were given either intravenous taurine or Ringer's solution 10 min prior to warm ischemia. Transaminases, histology, in vivo microscopy, intercellular adhesion molecules-1 (ICAM-1) expression, TNF-alpha and tissue hydroperoxide were compared between groups using analysis of variance (ANOVA) or ANOVA on ranks as appropriate.

RESULTS

Taurine significantly decreased transaminases and improved histologic outcome. Phagocytosis of latex beads, serum TNF-alpha levels and tissue hydroperoxide concentrations were also significantly reduced. Stickers in sinusoids and post-sinusoidal venules significantly decreased. In parallel, both leukocyte infiltration and ICAM-1 expression decreased (p < 0.05), while flow velocity of red blood cells as well as sinusoidal perfusion rate were improved (p < 0.05).

CONCLUSION

This study demonstrates that taurine blunts Kupffer cell-dependent hepatic pathology after warm ischemia in vivo via mechanisms including leukocyte-endothelial interaction, microcirculation disturbances and protection against lipid peroxidation.

Cytokines and chronic liver disease

From an immunological point of view, the healthy liver has been usually associated with the phenomenon of tolerance. A microenvironment of regulatory cytokines produced by liver Kuppfer cells and liver sinusoidal endothelial cells has contributed, together with resident dendritic cells, to generate a tolerogenic environment in this tissue. In this review we discussed the intrahepatic responses to different sorts of liver injury, such as hepatotrophic viruses, alcohol or putative self-antigens. In each case we analyzed the impact of different cytokines in the clinical outcome of the different pathological situations.

Induction of high-molecular-weight (HMW) tumor necrosis factor(TNF) alpha by hepatitis C virus (HCV) non-structural protein 3 (NS3) in liver cells is AP-1 and NF-κB-dependent activation

Chronic infection of hepatitis C virus (HCV)-infected patients is associated with the production of serum and interhepatic inflammatory cytokines including tumor necrosis factor alpha (TNF-alpha). In this study, we delineated part of the mechanism whereby HCV induces the synthesis of TNF-alpha in human liver cell lines HepG2 and Huh7. HepG2 transiently transfected with the full-length HCV cDNA expressed high-molecular-weight (HMW) TNF-alpha mRNAs, which were absent in the control cells. In addition tightly regulated expression of HCV NS3 in both HepG2 and Huh7 was found to induce the expression of HMW mRNAs and subsequently the production of biologically active TNF-alpha. Interestingly, the expression of NS3 protein in HepG2-NS3 or in Huh7-NS3 resulted in the activation of kinase (IKK-alpha) of NF-alphaB inhibitor (IalphaB) and in the enhancement of the DNA-binding activity of the nuclear transcription factor NF-kappaB. The inhibition of the transcription of TNF-alpha mRNAs and subsequently TNF-alpha production following the treatment of HepG2-NS3 or Huh7-NS3 transfectants with the inhibitor of NF-kappaB, Bay 11-7082, suggesting the importance of NF-kappaB for the regulation of NS3-mediated TNF-alpha expression in HepG2 and HeLa cells. Interestingly, data obtained from luciferase assays, in liver and in non-liver cells showed the contribution of NS3 protein in the regulation of TNF-alpha promoter through the activation of AP-1 and NF-kappaB. Our data indicate that the intrahepatic TNF-alpha production induced by HCV is transcriptionally up-regulated by HCV NS3. Therefore, HCV NS3 may have a potential role in the induction of intrahepatic inflammatory processes that occur during acute and chronic hepatitis C.

Treatment with Y-40138, a multiple cytokine production modulator, inhibits lipopolysaccharide- or tumour necrosis factor-alpha-induced production of pro-inflammatory cytokines and augments interleukin-10

N-[1-(4-[4-(pyrimidin-2-yl)piperazin-1-yl]methyl phenyl)cyclopropyl] acetamide . HCl (Y-40138) suppresses liver injury in concanavalin A- and D-galactosamine/lipopolysaccharide (LPS)-induced mouse hepatitis models. However, the mechanism of action of Y-40138 has not been fully investigated. In this study, we examined the effect of Y-40138 on cytokine production in mice. Cytokine production was induced by intraperitoneal injection of LPS (0.5 mg kg(-1)) or intravenous injection of recombinant mouse tumour necrosis factor (TNF)-alpha (10 mug mouse(-1)) in BALB/c mice. TNF-alpha and interleukin (IL)-10 reached maximum levels 1.5 h after the LPS injection. IL-12 and interferon-sigma (IFN-sigma) reached maximum levels 3 to 9 h after the injection. When Y-40138 was orally administered 30 min prior to the injection, it inhibited TNF-alpha, IL-12 and IFN-sigma production and augmented IL-10 production. Y-40138 also inhibited IL-12 production and augmented IL-10 production in TNF-alpha-stimulated mice. In IL-10 knockout mice, Y-40138 inhibited TNF-alpha and IL-12 production 1.5 h after the LPS injection but not after 3 h or later, unlike in wild mice. In addition, TNF-alpha production was inhibited by Y-40138 at concentrations that could not augment IL-10 production. These data suggest that Y-40138 modulates pro-inflammatory cytokine production by both IL-10-dependent and -independent mechanisms.

Tumour necrosis factor-alpha levels in hepatitis B virus-related chronic active hepatitis and liver cirrhosis and its relationship to Knodell and Child-Pugh scores

Although both chronic active hepatitis-B (CAH-B) and liver cirrhosis (LC) are characterised by various degrees of inflammation and hepatocyte necrosis, in advanced stage cirrhosis, marked fibrosis develops and inflammation and tissue necrosis diminishes. In this study, we aimed to investigate serum tumour necrosis factor-alpha (TNF-alpha) concentration in patients with CAH-B and LC and its relationship to disease activity. Serum samples were taken from 30 patients with CAH-B and 30 with LC at different stages of the disease. TNF-alpha concentrations were measured by the ELISA technique. Results were compared with those of 30 healthy controls. Mean plasma TNF-alpha levels were found as 2.47 +/- 2.98, 0.8 +/- 1.21 and 0.72 +/- 1.08 pg/ml in CAH-B, LC and control groups, respectively. TNF-alpha levels were significantly higher in CAH-B group than LC and control groups (p <0.01 and p < 0.05, respectively). Although mean plasma TNF-alpha level of cirrhotic patients at Child-A stage was markedly high (3.31 +/- 0.15), no significant difference has been found between LC and control groups (p > 0.05). TNF-alpha concentrations were positively correlated with hepatitis activity index (Knodell's score) in CAH-B group whereas negatively correlated with Child-Pugh score in LC group (r =0.73, p < 0.01 and r = -0.42, p < 0.05, respectively). Our study showed that TNF-alpha level increases in patients with CAH-B correlated with histologic activity index. So it can be used to evaluate disease activity. Additionally, marked reduction of TNF-alpha concentration in advanced cirrhosis suggested that TNF-alpha production is determined by hepatic damage and inflammation.

Effect of pentoxifylline on levels of pro-inflammatory cytokines during chronic hepatitis C

The cellular and humoral natural immune response induced by hepatitis C virus (HCV) is commonly unable to eradicate the virus. HCV is a highly mutable, hepatotropic RNA virus that causes acute and chronic hepatitis, an infection that involves the production of various cytokines. The aim of the study is to analyse the expression of pro-inflammatory cytokines IL-1beta, TNF-alpha, IFN-gamma and the chemokine CXCL8 (IL-8) in liver tissue and their expression and secretion in PBMC of patients with chronic hepatitis C (CHC), in response to pentoxyfilline (PTX). We studied six CHC patients, naive to treatment. Patients received PTX 400 mg twice a day/8 weeks. Pentoxyfilline resulted in decreased expression of mRNA of liver IL-1beta, TNF-alpha and IFN-gamma: 144.2 versus 83.5 molecules of IL-1beta (P < 0.05), TNF-alpha 194.3 versus 17.6 molecules (P = 0.03) and IFN-gamma 26.1 versus 0.5 molecules (P = 0.04). Following PTX, PBMC exhibited a decrease in IFN-gamma mRNA 12.2 versus 1.5 molecules (P = 0.028) and CXCL8 4.2 versus 2.5 molecules (P = 0.027). In PBMC, only the secretion of TNF-alpha was decreased 1109 versus 933.5 pg/ml, P = 0.046. Production of cytokines both locally (within the liver) and systemically (PBMC) may serve as biomarkers of the infection with hepatitis C. PTX inhibits the expression of several pro-inflammatory cytokines in the liver. These results indicate that it is worth exploring PTX in hepatitis in future clinical trials in nonresponders to antiviral treatment.

Treatment of chronic hepatitis C in non-responsive patients with pegylated interferon associated with ribavirin and thalidomide: report of six cases of total remission

Hepatitis C virus (HCV) infection is an important public health issue worldwide. It is estimated that over 170 million people are infected with the virus. The present study reports six cases in which patients did not respond to combination therapy with pegylated interferon and ribavirin. However, after the addition of thalidomide to the therapy, the patients presented negative RNA PCR. The use of thalidomide combined with pegylated interferon and ribavirin for the treatment of hepatitis C is described here for the first time in the related literature.

Liver endothelial cells promote LDL-R expression and the uptake of HCV-like particles in primary rat and human hepatocytes

Low-density lipoprotein (LDL) is an important carrier of plasma cholesterol and triglycerides whose concentration is regulated by the liver parenchymal cells. Abnormal LDL regulation is thought to cause atherosclerosis, while viral binding to LDL has been suggested to facilitate hepatitis C infection. Primary hepatocytes quickly lose the ability to clear LDL during in vitro culture. Here we show that the coculture of hepatocytes with liver sinusoidal endothelial cells (LSEC) significantly increases the ability of hepatocytes to uptake LDL in vitro. LDL uptake does not increase when hepatocytes are cocultured with other cell types such as fibroblasts or umbilical vein endothelial cells. We find that LSECs induce the hepatic expression of the LDL receptor and the epidermal growth factor receptor. In addition, while hepatocytes in single culture did not take up hepatitis C virus (HCV)-like particles, the hepatocytes cocultured with LSECs showed a high level of HCV-like particle uptake. We suggest that coculture with LSECs induces the emergence of a sinusoidal surface in primary hepatocytes conducive to the uptake of HCV-like particles. In conclusion, our findings describe a novel model of polarized hepatocytes in vitro that can be used for the study of LDL metabolism and hepatitis C infection.

Taurine improves graft survival after experimental liver transplantation

Relevant mechanisms of reperfusion injury after liver transplantation are most likely mediated by activated Kupffer cells. Recently, it has been demonstrated that taurine prevents Kupffer cell-activation in vitro. Thus, this study was designed to assess the effects of taurine after liver transplantation. Female Sprague-Dawley rats (210-240 g) were infused with taurine dissolved in normal saline, before organ harvest. Controls were infused with the same volume of normal saline without taurine. Following 4 hours of cold ischemia, liver transplantation was performed. Graft and animal survival, serum transaminases, liver histology, perfusion data of intravital microscopy, blood distribution at reperfusion, and both phagocytosis of Kupffer cells and expression of tumor necrosis factor alpha (TNF-alpha) to index cellular activation were investigated. For comparison, both, analysis of variance (ANOVA) and Fisher's exact test were used as appropriate. Results are presented as mean +/- SEM. Controls survived in 60% of cases. Taurine improved survival in a dose-dependent manner to 100% (P < 0.05). In controls, mean aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactic dehydrogenase (LDH) serum levels increased to 3,260 +/- 814; 1,703 +/- 432; and 14,071 +/- 3,177 U/L, respectively, after transplantation. In contrast, these values were between 20 and 45% of control values after taurine (P < 0.05). Histology taken after transplantation confirmed the significant protective effects of taurine, including the reduction of TNF-alpha expression. Time until homogeneous reperfusion of the graft improved to 50% of control values (P < 0.05). Further, taurine significantly decreased both phagocytosis of latex beads by Kupffer cells and leukocyte-endothelial cell interaction. In parallel, flow velocity of red blood cells as well as acinar and sinusoidal perfusion improved (P < 0.05). In conclusion, these data show for the first time in vivo that taurine minimizes reperfusion injury after liver transplantation. Decreased leukocyte-endothelial cell interaction and improved microcirculation are the proposed mechanisms, which are most likely Kupffer cell-dependent.

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