Induction of tumour necrosis factor (TNF) receptor type p55 and p75 in patients with chronic hepatitis C virus (HCV) infection

Managing Psoriasis in Patients with HBV or HCV Infection: Practical Considerations

Considered more efficacious and safer than traditional systemic drugs, biologic therapies have dramatically improved the quality of life of patients with psoriasis. Recently, there has been a proliferation of new targeted treatment options, including anti-interleukin-17, anti-interleukin-12/23, as well as small-molecule drugs such as apremilast. There are nevertheless some concerns regarding their use, especially in patients with chronic infections such as hepatitis B virus (HBV) and hepatitis C virus (HCV). It has been estimated that two billion individuals are infected with HBV worldwide and approximately 240 million have chronic HBV infection. Moreover, there are approximately 71 million individuals with chronic HCV infection worldwide, with a high percentage of them unaware of being infected. As patients with HBV and HCV infections are excluded from controlled clinical trials investigating new drugs, data regarding their safety in patients with psoriasis are based almost exclusively on case reports and small retrospective cohort studies and need to be constantly updated. The risk of HBV reactivation can be defined as: high risk (≥ 10%), moderate risk (1-10%), and low risk (< 1%) depending on the type of immunosuppressive therapy stratified by the presence or absence of hepatitis B surface antigen but positivity to anti-hepatitis B core antigen. Hepatitis B surface antigen-positive patients treated with tumor necrosis factor-α inhibitors, ustekinumab, or cyclosporine carry a high or moderate risk of HBV reactivation and should be considered candidates for prophylactic anti-HBV therapy. Once therapy is commenced, it is important to check HBV DNA levels every 3 months. Hepatitis B virus reactivation typically occurs with immune reconstitution and therefore antiviral therapy should continue for 6-12 months after stopping immunosuppression. Hepatitis B surface antigen-positive patients who are prescribed methotrexate, acitretin, or apremilast have a low risk and need to be monitored for viral reactivation by determining alanine aminotransferase and HBV DNA levels every 3 months. No conclusive data are available for interleukin-17 and interleukin-23 inhibitors. Anti-hepatitis B core antigen-positive patients treated with tumor necrosis factor-α inhibitors, ustekinumab, and cyclosporine are linked to a moderate risk of reactivation, and they should preferably undergo HBV DNA or hepatitis B surface antigen and alanine aminotransferase testing rather than be subjected to routine pre-emptive therapy. Anti-hepatitis B core antigen-positive patients receiving methotrexate, acitretin, or apremilast have a low risk of reactivation and do not require anti-HBV therapy, nor should monitoring be considered mandatory. No conclusive data are available for interleukin-17 and interleukin-23 inhibitors.

Inflammatory and cardiovascular diseases biomarkers in chronic hepatitis C virus infection: A review

Hepatitis C virus (HCV) infects 180 million people worldwide and over 4 million people in the United States. HCV infection is a major cause of chronic liver disease and is recognized as a risk factor for clinical cardiovascular disease (CVD). Many studies have shown increased prevalence of cardiac and inflammatory biomarkers in patients with chronic HCV infection (CHC), and though these markers may be used to risk stratify people for cardiac disease in the general population their role in the HCV population is unknown. Patients with CHC have elevated cardiac and inflammatory biomarkers compared to noninfected controls which may play a role in CVD risk stratification. We undertook a systematic review of inflammatory and cardiac biomarkers in people with HCV infection with a focus on the effect of CHC on serum levels of these markers and their utility as predictors of CVD in this population. Medline, EMBASE, and Cochrane databases were searched for relevant articles until June 2019. A total of 2430 results were reviewed with 115 studies included. Our review revealed that HCV infection significantly alters serum levels of markers of inflammation, endothelial function, and cardiac dysfunction prior to HCV treatment, and some of which may change in response to HCV therapy. Current risk stratification tools for development of CVD in the general population may not account for the increased inflammatory markers that appear to be elevated among HCV‐infected patients contributing to increased CVD risk.

Macrophage Activation and the Tumor Necrosis Factor Cascade in Hepatitis C Disease Progression Among HIV-Infected Women Participating in the Women's Interagency HIV Study

BACKGROUND

HIV/hepatitis C-coinfected persons experience more rapid liver disease progression than hepatitis C virus (HCV) monoinfected persons, even in the setting of potent antiretroviral therapy.

METHODS

We sought to articulate the role of macrophage activation and inflammation in liver disease progression by measuring serial soluble markers in HIV/HCV-coinfected women. We compared markers measured during retrospectively defined periods of rapid liver disease progression to periods where little or no liver disease progression occurred. Liver disease progression was defined by liver biopsy, liver-related death or the serum markers AST-to-platelet ratio index and FIB-4. Soluble CD14, sCD163, lipopolysaccharide (LPS), tumor necrosis factor (TNF) receptor II, interleukin-6, and chemokine ligand 2 (CCL 2) were measured at 3 time points over 5 years.

RESULTS

One hundred six time intervals were included in the analysis: including 31 from liver disease progressors and 75 from nonprogressors. LPS, sCD14, interleukin-6, and CCL2 levels did not differ in slope or quantity over time between rapid liver disease progressors and nonprogressors. TNFRII and sCD163 were significantly higher in liver disease progressors at (P = 0.002 and <0.0001 respectively) and preceding (P = 0.01 and 0.003 respectively) the liver fibrosis outcome in unadjusted models, with similar values when adjusted for HIV RNA and CD4 count.

CONCLUSIONS

In women with HIV/HCV coinfection, higher sCD163 levels, a marker of macrophage activation, and TNFRII levels, implying activation of the TNF-α system, were associated with liver disease progression. Our results provide an addition to the growing body of evidence regarding the relationship between macrophage activation, inflammation, and liver disease progression in HIV/HCV coinfection.

TNF-α Induced by Hepatitis C Virus via TLR7 and TLR8 in Hepatocytes Supports Interferon Signaling via an Autocrine Mechanism

Invasion by infectious pathogens can elicit a range of cytokine responses from host cells. These cytokines provide the initial host defense mechanism. In this report, we demonstrate that TNF-α, a pro-inflammatory cytokine, can be induced by hepatitis C virus (HCV) in its host cells in a biphasic manner. The initial induction of TNF-α by HCV was prompt and could be blocked by the antibody directed against the HCV E2 envelope protein and by chemicals that inhibit endocytosis, indicating the specificity of endocytic uptake of HCV in this induction. Further studies indicated that the induction of TNF-α was dependent on toll-like receptors 7 and 8 (TLR7/8) but not on other intracellular pattern recognition receptors. Consistently, siRNA-mediated gene silencing of the downstream effectors in the TLR7/8 signaling pathway including MyD88, IRAK1, TRAF6, TAK1 and p65 NF-κB suppressed the expression of TNF-α. The role of p65 NF-κB in the induction of TNF-α via transcriptional up-regulation was further confirmed by the chromatin immunoprecipitation assay. TNF-α induced by HCV could activate its own receptor TNFR1 on hepatocytes to suppress HCV replication. This suppressive effect of TNF-α on HCV was due to its role in supporting interferon signaling, as the suppression of its expression led to the loss of IFNAR2 and impaired interferon signaling and the induction of interferon-stimulated genes. In conclusion, our results indicate that hepatocytes can sense HCV infection via TLR7/8 to induce the expression of TNF-α, which inhibits HCV replication via an autocrine mechanism to support interferon signaling.

Hepatitis C virus (HCV) patients have increased levels of circulating tumor necrosis factor-α (TNF-α). In this report, we demonstrate that HCV can directly induce the expression of TNF-α in hepatocytes in a biphasic manner via NF-κB. The induction of TNF-α by HCV in the first phase is prompt, requires no HCV gene expression and is dependent on TLR7 and TLR8 and their downstream effectors. TNF-α induced by HCV supports interferon signaling via an autocrine mechanism and suppresses HCV replication, as abolishing the expression of TNF-α or its receptor TNFR1 results in the loss of IFNAR2, a subunit of the type I interferon receptor, and an increase of HCV replication. Our studies thus reveal an interesting interplay between HCV and hepatocytes, with the virus attempting to blunt the IFN response by depleting IFNAR2 and the host cell overcoming this blunting effect of HCV by using TNF-α to restore the expression of IFNAR2.

Diagnostic Value of Serum Level of Soluble Tumor Necrosis Factor Receptor IIα in Egyptian Patients With Chronic Hepatitis C Virus Infection and Hepatocellular Carcinoma

BACKGROUND

The prognosis of hepatocellular carcinoma (HCC) is unfavorable and needs serum markers that could detect it early to start therapy at a potentially curable phase.

OBJECTIVES

The aim of this study was to determine the value of serum soluble tumor necrosis factor (TNF) receptor-IIα (sTNFR-IIα) in diagnosis of HCC in patients with chronic hepatitis C virus (HCV) infection.

PATIENTS AND METHODS

The study was performed on 110 subjects who were classified into five groups. Group I included 20 patients with chronic noncirrhotic HCV infection and persistently normal transaminases for ≥6 months. Group II included 20 patients with chronic noncirrhotic HCV infection and elevated transaminases. Group III included 20 patients with Chronic HCV infection and liver cirrhosis. Group IV included 20 patients with chronic HCV infection with liver cirrhosis and HCC. Group V included 30 healthy age and sex-matched controls. Medical history was taken from all participants and they underwent clinical examination and abdominal ultrasonography. in addition, the following laboratory tests were requested: liver function tests, complete blood count, HBsAg, anti-HCVAb, HCV-RNA by qualitative PCR, and serum levels of α-fetoprotein (AFP) and sTNFR-IIα.

RESULTS

The serum level of sTNFR-IIα was significantly higher in patients with HCC in comparison to the other groups. A positive correlation was found between the serum levels of sTNFR-IIα and AST and ALT in patients of group-II. Diagnosis of HCC among patients with HCV infection and cirrhosis could be ascertained when sTNFR-IIα is assessed at a cutoff value of ≥ 250 pg/mL.

CONCLUSIONS

Serum sTNFR-IIα could be used as a potential serum marker in diagnosing HCC among patients with HCV infection.

Liver disease and diabetes: association, pathophysiology, and management

Diabetes is associated with a spectrum of liver diseases including nonalcoholic liver disease, steatohepatitis, and liver cirrhosis with their increased complications and mortality. Hepatitis C virus (HCV) and its associated liver cirrhosis has been associated with diabetes through insulin resistance. Cryptogenic diabetes occurs as a consequence of liver cirrhosis with the pathophysiology being complex, but mostly attributed to the increased insulin resistance in muscle, liver, and adipose tissue. As for the management of diabetes in patients with liver disease, lifestyle modification plays an important role. Oral diabetic medications are contraindicated in patients with advanced liver diseases with associated cirrhosis, ascites, or encephalopathy. As for stable liver disease, metformin and thiazolenediones have shown mixed results, with some showing them to be effective in improving liver transaminases in addition to histological improvement in steatosis and inflammation. α-glucosidase inhibitors may be helpful in decreasing hepatic encephalopathy. Upregulation of Dipeptidyl peptidase-4 (DPP-4) has been suggested as a possible pathogenetic mechanism for HCV-related insulin resistance, and treatment with DPP-4 inhibitors could improve insulin sensitivity in diabetic patients with liver disease. Patients with impaired liver function with associated insulin resistance may need increased insulin requirements. On the other hand patients with altered liver metabolism might need decreased insulin requirements.

Regulation and dysregulation of tumor necrosis factor receptor-1

TNF is an essential regulator of the immune system. Dysregulation of TNF plays a role in the pathology of many auto-immune diseases. TNF-blocking agents have proven successful in the treatment of such diseases. Development of novel, safer or more effective drugs requires a deeper understanding of the regulation of the pro-inflammatory activities of TNF and its receptors. The ubiquitously expressed TNFR1 is responsible for most TNF effects, while TNFR2 has a limited expression pattern and performs immune-regulatory functions. Despite extensive knowledge of TNFR1 signaling, the regulation of TNFR1 expression, its modifications, localization and processing are less clear and the data are scattered. Here we review the current knowledge of TNFR1 regulation and discuss the impact this has on the host.

Soluble TNF-alpha-receptors I are prognostic markers in TIPS-treated patients with cirrhosis and portal hypertension

Background

TNFα levels are increased in liver cirrhosis even in the absence of infection, most likely owing to a continuous endotoxin influx into the portal blood. Soluble TNFα receptors (sTNFR type I and II) reflect release of the short-lived TNFα, because they are cleaved from the cells after binding of TNFα. The aims were to investigate the circulating levels of soluble TNFR-I and -II in cirrhotic patients receiving TIPS.

Methods

Forty-nine patients with liver cirrhosis and portal hypertension (12 viral, 37 alcoholic) received TIPS for prevention of re-bleeding (n = 14), therapy-refractory ascites (n = 20), or both (n = 15). Portal and hepatic venous blood was drawn in these patients during the TIPS procedure and during the control catheterization two weeks later. sTNFR-I and sTNFR-II were measured by ELISA, correlated to clinical and biochemical characteristics.

Results

Before TIPS insertion, sTNFR-II levels were lower in portal venous blood than in the hepatic venous blood, as well as in portal venous blood after TIPS insertion. No significant differences were measured in sTNFR-I levels. Hepatic venous levels of sTNFR-I above 4.5 ng/mL (p = 0.036) and sTNFR-II above 7 ng/mL (p = 0.05) after TIPS insertion were associated with decreased survival. A multivariate Cox-regression survival analysis identified the hepatic venous levels of sTNFR-I (p = 0.004) two weeks after TIPS, and Child score (p = 0.002) as independent predictors of mortality, while MELD-score was not.

Conclusion

Hepatic venous levels of sTNFR-I after TIPS insertion may predict mortality in patients with severe portal hypertension.

The increased ratio of CD4+/CD8+ was positively correlated with inflammation in hepatitis C patients with metabolic syndrome

BACKGROUND/AIMS

The incidence of metabolic syndrome (MS) in hepatitis C patients in Taiwan is not well known. Although the ratio of CD4(+)/CD8(+) T lymphocytes is considered to possibly affect the pathogenesis of hepatitis C, the effects of MS on CD4(+)/CD8(+) T lymphocytes remain unknown. The aims of this study to assess (1) the incidence of MS, (2) the inflammation status and fatty changes of liver, and (3) changes in their CD4(+)/CD8(+) T-lymphocyte ratio in patients with hepatitis C.

METHODS

60 hepatitis C patients were classified into MS or non-MS group. The terms of anthropometric data, MS components, and T-lymphocytes were assessed.

RESULTS

The proportion of hepatitis C patients suffering from MS was 26.7% in this study. The CD4(+)/CD8(+) T-lymphocyte ratios were higher in patients with MS than non-MS group. Hepatitis C patients with MS also had higher levels of ferritin than non-MS. Moreover, the level of ferritin positively correlated with the severity of fatty liver. The CD4(+)/CD8(+) T-lymphocyte ratio is also positively correlated with ferritin level and the severity of fatty liver.

CONCLUSIONS

Hepatitis C patients with MS had higher ratio of CD4(+)/CD8(+) T lymphocyte, which is associated with a high inflammatory response and a fatty change of liver.

The influence of anti-TNF therapy on the course of chronic hepatitis C virus infection in patients with inflammatory bowel disease

BACKGROUND

The immunosuppressive potential of anti-tumor necrosis factor (TNF) in exacerbating chronic hepatitis C virus (HCV) infection has been a major concern. We aim to critically analyze the impact of anti-TNF on the course of chronic HCV infection in patients with concurrent inflammatory bowel disease (IBD) and HCV infection.

MATERIALS AND METHODS

Patients with diagnosis of IBD and HCV were identified retrospectively through the University of Pennsylvania Health System electronic database. Data assessed included demographics, duration of IBD and HCV infection, HCV RNA levels, HCV genotype, liver histology, hepatic biochemical tests (HBT) and IBD disease activity index.

RESULTS

A total of 4,274 IBD and 3,523 HCV patients were identified from 10/1998 to 05/2010. Thirty-seven patients had concurrent HCV infection and IBD, of which 23 patients were eligible (61 % CD; 39 % UC). Five patients (22 %) received anti-TNF therapy (infliximab). Two patients received pegylated interferon and ribavirin (both were non-responders). Overall, three patients had clinical remission and one patient had clinical response to infliximab. When compared to baseline, one patient had HBT improvement, three patients remained stable and one patient had HBT elevation, which was likely due to progressive liver disease in view of HIV co-infection.

CONCLUSION

This represents the first critical analysis assessing the impact of anti-TNF therapy on the course of chronic HCV in IBD patients. Concurrent HCV infection in IBD patients is uncommon. Treatment of IBD with infliximab in HCV patients did not result in flares in hepatic biochemical tests while there was an improvement in the IBD disease activity score.

Synergistic effects of antibodies against high-mobility group box 1 and tumor necrosis factor-α antibodies on D-(+)-galactosamine hydrochloride/lipopolysaccharide-induced acute liver failure

High-mobility group box 1 (HMGB1) protein is released into the serum after tissue damage, and serves as a warning signal to enhance the inflammatory response. Acute liver injury is one of the diseases that starts with tissue damage and ends with systemic inflammation. We used D-(+)-galactosamine hydrochloride (D-GalN)/lipopolysaccharide (LPS)-treated mice as an acute liver injury model to explore the functions of HMGB1 in more detail. HMGB1 is released into the serum at a very early stage of D-GalN/LPS-induced acute liver injury. It upregulates the expression of tumor necrosis factor-α (TNF-α), interleukin-6, inducible nitric oxide synthase, and tissue factor. TNF-α and HMGB1 form a positive feedback loop to amplify the downstream signals. mAbs against HMGB1 and TNF-α have synergistic effects in protecting mice from D-GalN/LPS-induced acute liver failure. The results suggest that HMGB1 is a key mediator in D-GalN/LPS-induced acute liver injury. Tissue damage and cell necrosis shortly after administration of D-GalN and LPS lead to early HMGB1 release, and HMGB1 acts synergistically with TNF-α to promote pathological processes in acute liver failure.

Impact of hepatitis B and C co-infection on health-related quality of life in HIV positive individuals

PURPOSE

Concurrent infection with HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) often occurs due to the commonality in risk factors for acquisition. Few studies have examined the effect of co-infection on health-related quality of life (HRQOL) in HIV positive individuals.

METHODS

Ontario HIV Treatment Network Cohort Study (OCS) participants who completed an annual interviewer-administered questionnaire on up to three occasions were included. Generalized estimating equations (GEE) were used to assess the impact of HBV and HCV co-infection on physical and mental HRQOL component summary scores (range 0-100) as measured by the Medical Outcomes SF-36 health survey.

RESULTS

As of March 2010, 1,223 participants had completed the questionnaire; 964 were HIV mono-infected, 128 were HIV-HBV co-infected, 112 were HIV-HCV co-infected, and 19 were HIV-HBV-HCV tri-infected. Eighty percent were male, median age 46 (IQR 40-53) years, 61% Caucasian, median CD4 count 464 (IQR 319-636) cells/mm(3), and 74% had undetectable HIV viremia. Physical HRQOL was lower in HIV-HBV and HIV-HCV co-infected individuals (49.4 (IQR 42.0-53.9) and 48.1 (IQR 36.9-52.8) vs. 51.5 (IQR 45.0-55.4); p = 0.01 and <0.0001) compared to mono-infected individuals. In the multivariable GEE model, the negative impact of HCV remained significant (-2.18; p = 0.01) after adjusting for drug use, smoking, age, and gender. Unadjusted mental HRQOL was lower in HIV-HCV co-infected individuals (44.6 (IQR 34.6-54.0) vs. 48.9 (IQR 36.8-55.9); p = 0.03) compared to mono-infected individuals but no association of mental HRQOL with either co-infection was observed in multivariable GEE models.

CONCLUSIONS

HCV appears to negatively impact physical HRQOL suggesting a greater health burden for co-infected individuals. HBV and HCV co-infections were not related to lower mental HRQOL among people living with HIV/AIDS.

HIV antiretroviral medications and hepatotoxicity

PURPOSE OF REVIEW

This review considers the differential diagnosis, pathophysiology and risk of hepatotoxicity of specific antiretroviral medications.

RECENT FINDINGS

Currently prescribed antiretroviral medications are associated with an incidence of grade 3/4 liver enzyme elevation of less than 5%. Clinically apparent hepatotoxicity rates are much lower. The risk of adverse events with combination HIV and hepatitis C virus treatments is low, assuming that several nucleosides including didanosine and stavudine are avoided.

SUMMARY

Irrespective of the HIV antiretroviral regimen prescribed, careful observation of liver function and enzymes is advised, especially in those with comorbid liver disease. The majority of patients do not experience treatment-limiting liver toxicities, achieve virological suppression, and realize immunological restoration.

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.

HCV-related proteins activate Kupffer cells isolated from human liver tissues

PURPOSE

It was reported from this laboratory that Kupffer cells (KCs) were activated in patients infected with HCV. Since dendritic cells, monocytes, and macrophages were activated by stimulation with HCV-related proteins, the specific aim of this study was to investigate the role of HCV-related proteins in activation of KCs, the signal pathway of activation of KCs mediated by Toll-like receptor (TLR) 4, and the influence of HCV infection on function of KCs.

METHODS

Kupffer cells isolated from non-cancerous surgical specimen were co-cultured with HCV-related proteins (Core, NS3, NS4, and NS5), and production of cytokines (TNF-α, IL-1β, and IL-10) and hydrogen peroxide were assessed. Furthermore, effects of neutralization antibodies against the TLR2, TLR3, or TLR4, and cytochalasin B on the production TNF-α by KCs were investigated.

RESULTS

Kupffer cells produced markedly a proinflammatory cytokine TNF-α by stimulation with all HCV-related proteins studied, and values were as same as production by KCs stimulated with LPS. Importantly, this production in the case of NS3 was significantly blunted by about 60% by neutralization antibodies against the TLR4, but not cytochalasin B. Production of TNF-α by isolated KCs stimulated with LPS was significantly greater in the HCV-infected livers than the HCV/HBV-negative livers.

CONCLUSIONS

These results indicated that HCV-related proteins may cause prolonged activation of KCs in the HCV-infected liver, leading to accumulation of inflammatory cytokines that contribute to DNA damage and carcinogenesis. Furthermore, function of KCs was difference between patients infected with and without HCV infection.

Evidence of a significant role for Fas-mediated apoptosis in HCV clearance during pegylated interferon plus ribavirin combination therapy

BACKGROUND

The role of apoptosis in treatment-induced HCV clearance is controversial. We sought to assess the kinetics of serum apoptosis-related cytokines during pegylated interferon-α2a or -α2b plus weight-based ribavirin therapy for genotype 1 chronic HCV infection.

METHODS

Serum levels of soluble Fas (sFas), soluble Fas ligand (sFasL) and soluble tumour necrosis factor receptor I (sTNF-RI) were measured at baseline, week 12 and 24 weeks after the end of therapy.

RESULTS

Sustained virological response (SVR) was achieved in 46% of the 164 included patients, 29% had a non-response (NR) and 25% had relapse (RR). NR patients presented with higher levels of sFasL at baseline and lower levels of sTNF-RI at week 12 as compared to RR and SVR patients. Lower concentrations of sFas were observed in SVR patients 24 weeks after treatment as compared to RR and NR patients. An increase in sFas at week 12 followed by a significant drop 24 weeks after therapy was observed among SVR patients. An increase in sFasL during and after treatment was observed in RR and SVR patients. NR patients exhibited an earlier drop in sTNF-RI levels as compared to RR and SVR patients.

CONCLUSIONS

Virological response during HCV therapy was associated with an increase of sFas and sFasL, and maintenance of increased concentrations of sTNF-RI.

Nuclear factor κB up-regulation of CCAAT/enhancer-binding protein β mediates hepatocyte resistance to tumor necrosis factor α toxicity

The sensitization of hepatocytes to cell death from tumor necrosis factor α (TNFα) underlies many forms of hepatic injury, including that from toxins. Critical for hepatocyte resistance to TNFα toxicity is activation of nuclear factor κB (NF-κB) signaling, which prevents TNFα-induced death by the up-regulation of protective proteins. To further define the mechanisms of hepatocyte sensitization to TNFα killing, immunoblot analysis comparing livers from mice treated with lipopolysaccharide (LPS) alone or LPS together with the hepatotoxin galactosamine (GalN) was performed to identify TNFα-induced protective proteins blocked by GalN. Levels of CCAAT/enhancer-binding protein β (C/EBPβ) were increased after LPS treatment but not GalN/LPS treatment. In a nontransformed rat hepatocyte cell line, TNFα-induced increases in C/EBPβ protein levels were dependent on NF-κB-mediated inhibition of proteasomal degradation. Pharmacological inhibition of c-Jun N-terminal kinase (JNK) did not affect C/EBPβ degradation, indicating that the process was JNK-independent. C/EBPβ functioned to prevent cell death as adenoviral C/EBPβ overexpression blocked TNFα-induced apoptosis in cells sensitized to TNFα toxicity by NF-κB inhibition. C/EBPβ inhibited TNFα-induced caspase 8 activation and downstream mitochondrial cytochrome c release and caspase 3 and caspase 7 activation. Studies in primary hepatocytes from c/ebpβ(-/-) mice confirmed that loss of C/EBPβ increased death from TNFα. c/ebpβ(-/-) mice were also sensitized to liver injury from a nontoxic dose of LPS or TNFα. The absence of jnk2 failed to reverse the GalN-induced block in C/EBPβ induction by LPS, again demonstrating that C/EBPβ degradation was JNK-independent.

CONCLUSION

C/EBPβ is up-regulated by TNFα and mediates hepatocyte resistance to TNFα toxicity by inhibiting caspase-dependent apoptosis. In the absence of NF-κB signaling, proteasomal degradation of C/EBPβ is increased by a JNK-independent mechanism and promotes death from TNFα.

[Etanercept and chronic infection by HCV and HBV]

Both psoriasis and chronic infections by HBV and HCV have high prevalence. Thus, it is relatively easy for them to coincide in the same patient. If the psoriasis requires systemic treatment, the dermatologist should consider the hepatic comorbidity when selecting an appropriate treatment. Cyclosporine, in addition to other well-known side effects, is an immunosuppressant that may condition worse evolution of the viral hepatitis. On the other hand, retinoids, psoralens and, above all, methotrexate may worsen the liver function. The anti-TNF-|A biological agents are not hepatotoxic and their theoretical contraindication in this context would be because of their action on the immune response and risk of reactivation of the hepatic infection. However, several studies have demonstrated that neither the viral load nor the hepatic inflammation parameters are generally modified negatively when they are used in hepatitis due to HCV. Their use in this context, with correct monitoring, seems, therefore, very reasonable. On the contrary, in chronic hepatitis B virus, there are cases of worsening, even with fatal outcome in some cases, and the use of these biological agents should be reserved for cases having greater need, and always be associated to antiviral treatment and strict monitoring. The review of the recent literature seems to allow the conclusion that the concomitant use of lamivudine would greatly reduce the risk of viral reactivation and, with this condition, the use of etanercept in some HBV+ patients may also be contemplated.

Tumor necrosis factor receptor 1 expression is upregulated in dendritic cells in patients with chronic HCV who respond to therapy

The present studies assessed the level of tumor necrosis factor receptor (TNFR) expression in peripheral blood mononuclear cells (PBMCs) subsets from patients with chronic HCV undergoing interferon α/ribavirin-based therapy (Ifn/R). Methods. TNFR family member mRNA expression was determined using quantitative real-time PCR assays (RTPCRs) in PBMC from 39 HCV+ patients and 21 control HCV− patients. Further subset analysis of HCV + patients (untreated (U), sustained virological responders (SVR), and nonresponders (NR)/relapsers (Rel)) PBMC was performed via staining with anti-CD123, anti-CD33, anti-TNFR1 or via RTPCR for TNFR1 mRNA. Results. A similar level of TNFR1 mRNA in PBMC from untreated HCV+ genotype 1 patients and controls was noted. TNFR1 and TNFR2 mRNA levels in PBMC from HCV+ patients with SVR were statistically different than levels in HCV(−) patients. A significant difference was noted between the peak values of TNFR1 of the CD123+ PBMC isolated from SVR and the NR/Rel. Conclusion. Upregulation of TNFR1 expression, occurring in a specific subset of CD123+ dendritic cells, appeared in HCV+ patients with SVR.

Soluble inflammatory markers as predictors of liver histological changes in patients with chronic hepatitis C virus infection

Host immune response seems to be mainly responsible for the progression of liver disease among patients with hepatitis C virus (HCV) infection. Immune activation involves the release of cytokines and their receptors that can be measured in plasma samples. The study aimed to evaluate the association between plasma levels of chemokines and soluble tumor necrosis factor receptors (sTNFR) and liver histological changes among patients with chronic HCV infection. Seventy-one treatment-naive patients were included. Plasma levels of CCL2, CCL3, CCL11, CCL24, CXCL9, CXCL10, sTNFR1, and sTNFR2 were measured and liver histological findings were reviewed. Plasma levels of CXCL9, sTNFR1, and sTNFR2 were significantly associated with liver fibrosis, with higher median levels found among patients with moderate/severe fibrosis (F >or= 2) if compared to those with no or mild fibrosis (p = 0.014; p = 0.012; p = 0.009, respectively). Plasma sTNFR2 levels were significantly associated with necroinflammatory activity, with higher median levels among patients with moderate/severe activity (A >or= 2) if compared to those with no or mild activity (2.34 ng/mL vs. 1.99 ng/mL; p = 0.019). In conclusion, plasma levels of CXCL9, sTNFR1, and sTNFR2 were independently associated with liver histological changes, suggesting a role of TNF activation and Th1-type cell-mediated immune response in the pathogenesis of HCV infection.

Gene expression profiling and network analysis reveals lipid and steroid metabolism to be the most favored by TNFalpha in HepG2 cells

BACKGROUND

The proinflammatory cytokine, TNFalpha, is a crucial mediator of the pathogenesis of several diseases, more so in cases involving the liver wherein it is critical in maintaining liver homeostasis since it is a major determiner of hepatocyte life and death. Gene expression profiling serves as an appropriate strategy to unravel the underlying signatures to envisage such varied responses and considering this, gene transcription profiling was examined in control and TNFalpha treated HepG2 cells.

METHODS AND FINDINGS

Microarray experiments between control and TNFalpha treated HepG2 cells indicated that TNFalpha could significantly alter the expression profiling of 140 genes; among those up-regulated, several GO (Gene Ontology) terms related to lipid and fat metabolism were significantly (p<0.01) overrepresented indicating a global preference of fat metabolism within the hepatocyte and those within the down-regulated dataset included genes involved in several aspects of the immune response like immunoglobulin receptor activity and IgE binding thereby indicating a compromise in the immune defense mechanism(s). Conserved transcription factor binding sites were identified in identically clustered genes within a common GO term and SREBP-1 and FOXJ2 depicted increased occupation of their respective binding elements in the presence of TNFalpha. The interacting network of "lipid metabolism, small molecule biochemistry" was derived to be significantly overrepresented that correlated well with the top canonical pathway of "biosynthesis of steroids".

CONCLUSIONS

TNFalpha alters the transcriptome profiling within HepG2 cells with an interesting catalog of genes being affected and those involved in lipid and steroid metabolism to be the most favored. This study represents a composite analysis of the effects of TNFalpha in HepG2 cells that encompasses the altered transcriptome profiling, the functional analysis of the up- and down- regulated genes and the identification of conserved transcription factor binding sites. These could possibly determine TNFalpha mediated alterations mainly the phenotypes of hepatic steatosis and fatty liver associated with several hepatic pathological states.

Serum levels of soluble Fas, soluble tumor necrosis factor-receptor II, interleukin-2 receptor and interleukin-8 as early predictors of hepatocellular carcinoma in Egyptian patients with hepatitis C virus genotype-4

BACKGROUND

Liver disease progression from chronic hepatitis C virus (HCV) infection to hepatocellular carcinoma (HCC) is associated with an imbalance between T-helper 1 and T-helper 2 cytokines. Evaluation of cytokines as possible candidate biomarkers for prediction of HCC was performed using soluble Fas(sFas), soluble tumor necrosis factor receptor-II (sTNFR-II), interleukin-2 receptor (IL-2R) and interleukin-8 (IL-8).

RESULTS

The following patients were recruited: 79 with HCV infection, 30 with HCC, 32 with chronic liver disease associated with elevated liver enzyme levels (with or without cirrhosis) in addition to 17 with chronic HCV with persistent normal alanine aminotransferase levels (PNALT). Nine normal persons negative either for HCV or for hepatitis B virus were included as a control group. All persons were tested for sFas, sTNFR-II, IL-2R and IL-8 in their serum by quantitative ELISA. HCC patients had higher levels of liver enzymes but lower log-HCV titer when compared to the other groups. HCC patients had also significantly higher levels of sFas, sTNFR-II and IL-2R and significantly lower levels of IL-8 when compared to the other groups. Exclusion of HCC among patients having PNALT could be predicted with 90 % sensitivity and 70.6 % specificity when sTNFR-II is [greater than or equal to] 389 pg/ml or IL-8 is < 290 pg/ml.

CONCLUSIONS

Serum TNFR-II, IL-2Ralpha and IL-8, may be used as combined markers in HCV-infected cases for patients at high risk of developing HCC; further studies, however, are mandatory to check these findings before their application at the population level.

[Hepatotoxicity induced by new immunosuppressants]

Immunosuppressants are among the pharmacological agents with the greatest potential to cause adverse reactions, although induction of hepatotoxicity is paradoxical from the pathogenic point of view, since the response of the innate and acquired immune system is a key element in the chain of events leading to chemical liver damage. Hepatotoxicity induced by immunosuppressants is difficult to evaluate since these drugs are sometimes used to treat liver diseases, or in combination with other drugs that can also cause hepatotoxicity, or in the context of liver transplantation, in which rejection or biliary complications can act as confounding factors. In addition, immunosuppressant therapy can favor the development of infections, which by themselves can cause liver damage, or reactivate latent chronic viral hepatitis. Corticosteroids and calcineurin inhibitors only exceptionally cause hepatotoxicity. Methotrexate at high doses and in patients with risk factors can induce advanced fibrosis and cirrhosis. Thiopurine agents can cause a spectrum of hepatic lesions, including hepatocellular of cholestatic lesions, and hepatic vascular alterations. Leflunomide has high hepatotoxic potential, especially when combined with methotrexate. Anti-tumor necrosis factor-alpha agents have rarely been associated with hepatotoxicity, often with detectable autoantibodies, and most of the reactions - some severe - have been linked to infliximab, especially when used in patients with rheumatological diseases.

Incidence and nature of infectious disease in patients treated with anti-TNF agents

Tumor necrosis factor alpha (TNF-alpha) inhibitors offer a targeted therapeutic strategy that contrasts with the nonspecific immunosuppressive agents traditionally used to treat most inflammatory diseases. These biologic agents have had a significant impact in ameliorating the signs and symptoms of inflammatory rheumatoid disease and improving patient function. From the onset of clinical trials, a central concern of cytokine blockade has been a potential increase in susceptibility to infections. Not surprisingly, a variety of infections have been reported in association with the use of TNF-alpha inhibitor agents. In particular, there is evidence suggesting an increased rate of granulomatous infections in patients treated with monoclonal TNF-alpha inhibitors. This review provides the incidence and nature of infections in patients treated with TNF-alpha inhibitor agents and reminds the clinician of the required vigilance in monitoring patients.

Eradication of hepatitis C virus by interferon improves whole-body insulin resistance and hyperinsulinaemia in patients with chronic hepatitis C

BACKGROUND/AIMS

To investigate whether eradication of hepatitis C virus (HCV) by interferon (IFN) therapy influences systemic glucose metabolism.

METHODS

Seventy-two patients with chronic hepatitis C were enrolled in this study. Patients received IFN therapy and were classified into two groups: sustained responders (n=48) and nonsustained responders (n=24). We analysed systemic glucose metabolism in terms of the following indices: homeostasis model assessment for insulin resistance (HOMA-IR) and beta-cell function (HOMA-beta), insulinogenic index (II), composite insulin sensitivity index (ISI composite) and the area under the curve of plasma glucose (PG-AUC) and serum insulin (SI-AUC) in oral glucose tolerance tests. In 28 sustained responders and 16 nonsustained responders, serum levels of soluble tumour necrosis factor receptor 2 (sTNFR2) were measured. Indices were determined before and 6 months after therapy.

RESULTS

In the sustained responders, HOMA-beta (P=0.0004) and SI-AUC (P=0.002) were significantly decreased and the ISI composite was increased (P=0.009), although there were no significant changes in HOMA-IR, II or PG-AUC. Serum sTNFR2 levels decreased significantly after therapy in sustained responders (P=0.001). In the nonsustained responders, there were no changes in any index.

CONCLUSIONS

Eradication of HCV by IFN therapy could improve whole-body insulin resistance and insulin hypersecretion with reduced serum TNF-alpha levels.

Circulating levels of interferon-gamma in course of hepatitis C virus-related arthritis

The aim was to weigh the serum concentrations of interferon gamma (IFN-gamma), a cytokine that enhances Th1-cell differentiation and suppresses collagen synthesis and angiogenesis, in two apparently distinct diseases, hepatitis C virus-related arthritis (HCVrA) and rheumatoid arthritis (RA), which share some overlapping immunological features. In this study, IFN-gamma serum levels were assayed by an ELISA method in 21 HCVrA patients and in 16 with RA. Very low IFN-gamma serum levels were found in five out of 21 patients with HCVrA and only in three out of 16 RA patients. Median value (range) resulted decrease in both HCVrA and RA groups, that is, 0.29 (0.04-1.49) versus 0.20 (0.05-1.18) IU/mL, P = 0.58. No correlation was evidenced with hepatic and arthritic involvements, nor between IFN-gamma serum levels and viral replication and moreover with the positivity of antinuclear antibody, rheumatoid factor, and anti-cyclic citrullinated peptides antibodies. These results show that IFN-gamma behavior appears similar in HCVrA and RA groups reinforcing the lack of significant differences between HCVrA and RA patients. Low circulating levels could be explained with the fact that IFN-gamma is not an isolate cytokine, but a piece of composite system regulated in a complex fashion, with many different factors contributing.

Use of tumor necrosis factor-alpha (TNF-alpha) antagonists infliximab, etanercept, and adalimumab in patients with concurrent rheumatoid arthritis and hepatitis B or hepatitis C: a retrospective record review of 11 patients

An understanding of the cytokine cascade in a rheumatoid joint has led to the development of new therapeutic options, including drugs targeting tumor necrosis factor-alpha (TNF-alpha). The safety profile of these agents in patients with hepatitis-induced liver disease, however, remains a concern because of risks associated with immune suppression. To examine the effect of three different TNF-alpha antagonists, infliximab, etanercept, and adalimumab, on serum transaminases and hepatitis viral load in patients with rheumatoid arthritis (RA) and concurrent hepatitis B (HBV) or hepatitis C (HCV). Medical records of 11 patients with diagnosis of RA and documented seropositivity for hepatitis B or hepatitis C were retrospectively reviewed for worsening of hepatic inflammation and viral proliferation as measured by a rise in aspartate aminotransferase (AST) or alanine aminotransferase (ALT) and viral load while using these agents. Three patients had RA with concurrent chronic HBV and eight patients had RA with concurrent chronic HCV. Seven patients remained on a single anti-TNF-alpha agent and four patients switched to a second anti-TNF-alpha agent due to treatment failure. Two patients showed a transient elevation in AST and/or ALT from normal, but in all 11 patients, AST and ALT levels were within one time the upper range of normal at the conclusion of the study. No significant increase in viral load was seen except one patient who showed a fourfold increase from baseline. Our case series supports results obtained from previous studies examining the safety of anti-TNF-alpha agents in patients with underlying hepatic disease. Use of these agents in patients with HBV or HCV may be associated with a transient transaminitis but appears to be safe overall. In both groups, frequent monitoring of serum transaminase levels and viral load is essential.

Hepatitis C virus infection enhances insulin resistance induced by visceral fat accumulation

BACKGROUND/AIMS

To clarify the impact of visceral obesity on hepatitis C virus (HCV)-infected patients, we examined the relationship between insulin resistance development and visceral fat accumulation.

METHODS

We analyzed 87 HCV-infected patients with mild fibrosis (stage 1 or 2) in comparison with 125 sex- and age-matched patients with non-alcoholic fatty liver disease (NAFLD). The degree of visceral fat area (VFA; cm(2)) at the umbilical level was measured by abdominal computed tomography and divided into two grades: no visceral obesity, VFA<100 and visceral obesity, VFA>/=100. Insulin resistance was evaluated by homeostasis model assessment of insulin resistance (HOMA-IR) and the quantitative insulin sensitivity check index (QUICKI). Pancreatic beta-cell function was evaluated by homeostasis model assessment of beta-cell function (HOMA-beta). Serum soluble tumour necrosis factor (TNF)-receptors 1 and 2 and adiponectin were measured.

RESULTS

Insulin resistance evaluated by HOMA-IR and QUICKI was correlated with visceral fat accumulation, and was higher in HCV patients than in NAFLD patients with visceral obesity. HOMA-beta was higher in HCV patients than in NAFLD patients for each VFA grade. Serum-soluble TNF-receptors 1 and 2 were higher in HCV patients than in NAFLD patients with visceral obesity.

CONCLUSIONS

Hepatitis C virus infection is a risk factor for development of insulin resistance, particularly in patients with visceral obesity.

Histological evaluation of liver in two rheumatoid arthritis patients with chronic hepatitis B and C treated with TNF-alpha blockade: case reports

Tumor necrosis factor (TNF)-alpha antagonists successfully modulate the pathogenesis of rheumatoid arthritis (RA). However, little is known about the effect of TNF-alpha blockade on the histology of chronic viral hepatitis. We describe the cases of two patients with RA, one with concurrent chronic hepatitis B virus and the other with hepatitis C virus infection who, as part of their evaluation, underwent liver biopsies while undergoing treatment with a TNF-alpha antagonist.

Induction of plasma (TRAIL), TNFR-2, Fas ligand, and plasma microparticles after human immunodeficiency virus type 1 (HIV-1) transmission: implications for HIV-1 vaccine design

The death of CD4(+) CCR5(+) T cells is a hallmark of human immunodeficiency virus (HIV) infection. We studied the plasma levels of cell death mediators and products--tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), Fas ligand, TNF receptor type 2 (TNFR-2), and plasma microparticles--during the earliest stages of infection following HIV type 1 (HIV-1) transmission in plasma samples from U.S. plasma donors. Significant plasma TRAIL level elevations occurred a mean of 7.2 days before the peak of plasma viral load (VL), while TNFR-2, Fas ligand, and microparticle level elevations occurred concurrently with maximum VL. Microparticles had been previously shown to mediate immunosuppressive effects on T cells and macrophages. We found that T-cell apoptotic microparticles also potently suppressed in vitro immunoglobulin G (IgG) and IgA antibody production by memory B cells. Thus, release of TRAIL during the onset of plasma viremia (i.e., the eclipse phase) in HIV-1 transmission may initiate or amplify early HIV-1-induced cell death. The window of opportunity for a HIV-1 vaccine is from the time of HIV-1 transmission until establishment of the latently infected CD4(+) T cells. Release of products of cell death and subsequent immunosuppression following HIV-1 transmission could potentially narrow the window of opportunity during which a vaccine is able to extinguish HIV-1 infection and could place severe constraints on the amount of time available for the immune system to respond to the transmitted virus.

An endogenous TNF-alpha antagonist induced by splice-switching oligonucleotides reduces inflammation in hepatitis and arthritis mouse models

Tumor necrosis factor-alpha (TNF-alpha) is a key mediator of inflammatory diseases, including rheumatoid arthritis (RA), and anti-TNF-alpha drugs such as etanercept are effective treatments. Splice-switching oligonucleotides (SSOs) are a new class of drugs designed to induce therapeutically favorable splice variants of targeted genes. In this work, we used locked nucleic acid (LNA)-based SSOs to modulate splicing of TNF receptor 2 (TNFR2) pre-mRNA. The SSO induced skipping of TNFR2 exon 7, which codes the transmembrane domain (TM), switching endogenous expression from the membrane-bound, functional form to a soluble, secreted form (Delta7TNFR2). This decoy receptor protein accumulated in the circulation of treated mice, antagonized TNF-alpha, and altered disease in two mouse models: TNF-alpha-induced hepatitis and collagen-induced arthritis (CIA). This is the first report of upregulation of the endogenous, circulating TNF-alpha antagonist by oligonucleotide-induced splicing modulation.

Human herpesvirus 6 infection in adult living related liver transplant recipients

To analyze human herpesvirus 6 (HHV-6) infection in adult living related liver transplantation, we performed a virological analysis, including viral isolation, serological assay, and real-time polymerase chain reaction, of serially collected blood samples from 67 recipients. In addition, cytokine levels were measured to determine their role in viral reactivation. HHV-6 was isolated from only 4 recipients (6.0%), and viral DNA was detected in 15 (22.4%) of the 67 recipients. A significant increase in HHV-6 immunoglobulin G antibody titers was observed in 19 (28.4%) of the 67 recipients. Finally, 26 recipients (38.8%) had HHV-6 reactivation 2-6 weeks after transplantation. HHV-6 associated clinical features were analyzed in the 17 recipients presenting with either viremia or DNAemia. Two recipients with viremia and 3 recipients with DNAemia had unexplained fever at the time of viral infection. An increase in aminotransferase levels was observed in 2 recipients with viremia and 3 recipients with DNAemia. Recipients with liver cirrhosis caused by hepatitis B virus or hepatitis C virus infection as the underlying disease were more likely to have HHV-6 infection (P = 0.025). Mortality at the last follow-up in recipients with HHV-6 reactivation was significantly higher than in those without viral reactivation (P = 0.0118). Plasma interleukin-6 levels were significantly higher in the recipients with HHV-6 viremia than in the recipients without viremia at 4 weeks post-transplant (P = 0.0411). Moreover, tumor necrosis factor alpha levels were also higher in recipients with HHV-6 viremia (P < 0.0001) or reactivation (P = 0.0011) than in recipients without viremia or reactivation 4 weeks post-transplant.

Immunomodulators, sFas and Fas-L as potential noninvasive predictors of IFN treatment in patients with HCV genotype-4

Recent studies have indicated that cytokines can be used as markers for disease progression in hepatitis C virus (HCV)-infected patients, therefore this study was conducted to determine the influence of pegylated IFN vs standard IFN on interleukin-2 receptor (IL-2R), IL-6R, IL-8, TNFR-I, TNFR-II, sFas, and sFas-L in Egyptian patients with chronic hepatitis C genotype 4, as no previous studies have been performed on this genotype. We also aim at establishing a possible relationship between these cytokines and the response to INF to determine whether they can be used as noninvasive markers for the response to INF therapy and as monitors for the outcome of treatment. Thirty-eight patients with chronic HCV hepatitis were investigated for the serum levels of the previously mentioned cytokines in a randomized opened controlled trial (22 patients treated with pegylated IFN and 16 patients treated with standard IFN). Cytokine levels were measured by ELISA at 0, 1 and 12 months of IFN therapy. There was marked increase in the serum levels of IL-2R and IL-6R in nonresponders to pegylated interferon, IL-8, TNFR-I and II were significantly higher in nonresponders to standard interferon but were also high in responders of pegylated interferon. sFas and sFas-L showed high levels among responders to pegylated interferon but the standard interferon was again less effective in this regard. Serum levels of TNFR-II, sFas and sFas-L have the potential to be used as serological markers for response to pegylated IFN therapy, and IL-8 is a predictor for nonresponse. Moreover, TNFR-I and II have the potential to be used as markers of response to standard IFN treatment. The persistent correlation between sFas and TNFR-II may elaborate the possible role of pegylated IFN in the induction of apoptosis as a possible new mechanism of viral clearance during treatment with pegylated interferon treatment.

Hepatic tumor necrosis factor signaling and nuclear factor-kappaB: effects on liver homeostasis and beyond

The proinflammatory cytokine TNF has a pivotal role in liver pathophysiology because it holds the capacity to induce both hepatocyte cell death and hepatocyte proliferation. This dual effect of TNF on hepatocytes reflects its ability to induce both nuclear factor kappaB (NF-kappaB)-dependent gene expression and cell death. Multiple studies have demonstrated the crucial role of the transcription factor NF-kappaB in the decision between life and death of a hepatocyte. Massive hepatocyte apoptosis preceding embryonic lethality in NF-kappaB-deficient mice constituted the first indication of an essential antiapoptotic function of NF-kappaB in the liver. Although many studies confirmed this crucial cytoprotective role of NF-kappaB in adult liver, a number of genetic studies recently obtained conflicting results on the exact role of NF-kappaB in different mouse models of TNF hepatotoxicity, demonstrating that caution should be taken when interpreting studies using different NF-kappaB-deficient mice in distinct models of liver injury. Recent reports showing a role for hepatic NF-kappaB activation in the proliferation of malignant cells during hepatocarcinogenesis, and in the progression of fatty liver diseases to insulin resistance and type 2 diabetes mellitus demonstrate that NF-kappaB can also have more detrimental effects in the liver. Moreover, its role in the development of the metabolic syndrome emphasizes that hepatic NF-kappaB activation might also have adverse effects on the endocrine system. Therefore, understanding the regulation of hepatic TNF signaling and NF-kappaB activation is of critical therapeutic importance. In this review, we summarize how studies on the role of NF-kappaB in different mouse models of liver pathologies have contributed to this understanding.

Host immune status and incidence of hepatocellular carcinoma among subjects infected with hepatitis C virus: a nested case-control study in Japan

A nested case-control study was conducted to examine the association between host immune status, as characterized by serum immune marker levels, and the development of hepatocellular carcinoma (HCC) up to 8 years later in persons with chronic hepatitis C virus (HCV) infection. Cases (n = 39) and matched controls (n = 117) were selected from participants of the Town C HCV Study in Japan between 1996 and 2004 and matched on age at first available sample (+/-1 year), gender, and length of follow-up. Separate analyses were done for each of three serum immune markers: soluble tumor necrosis factor-receptor II (sTNF-R2) and soluble intercellular adhesion molecule-1 (sICAM-1), as indicators of type 1, cell-mediated immune response, and soluble CD30 (sCD30), as an indicator of type 2, humoral immune response. The median concentrations of sTNF-R2, sICAM-1, and sCD30 among controls were 3,170 pg/mL, 305 ng/mL, and 3.0 units/mL, respectively, and were higher among cases (3,870 pg/mL, 372 ng/mL, and 3.3 units/mL, respectively). The risk of developing HCC among subjects with immune marker concentrations above the median levels of the controls was >2-fold greater than among subjects with lower concentrations for all three markers [sTNF-R2: odds ratio (OR), 6.9; 95% confidence interval (95% CI), 2.4-20.5; sICAM-1: OR, 2.0; 95% CI, 0.9-4.1; and sCD30: OR, 2.1; 95% CI, 1.0-4.7]. Simultaneous adjustment for all three markers revealed only sTNF-R2 to be associated with HCC risk (OR, 6.4; 95% CI, 2.0-20.6). Adjustment for alcohol consumption and HCV serotype did not materially alter these associations. Results from this prospective, community-based study suggest that a dysregulation in both type 1-related and type 2-related host immunity contributes to the development of HCV-associated HCC.

HIF-1alpha expression in response to lipopolysaccaride mediates induction of hepatic inflammatory cytokine TNFalpha

HIF-1alpha is a transcription factor that acts as a master regulator of gene expression induced by hypoxia. Recent studies have demonstrated that the potent inflammatory factor, lipopolysaccharide (LPS), can also activate HIF-1alpha in myeloid cells. However, the molecular mechanisms at the transcriptional level of HIF-1alpha induction by LPS remained undefined. Here, we investigated the regulatory mechanism of HIF-1alpha expression by LPS in hepatocytes and identified that LPS-induced HIF-1alpha mediate gene transcription of a typical inflammatory mediator, tumor-necrosis factor alpha (TNFalpha). Increased HIF-1alpha gene expression by LPS was defined in a series of hepatic cell lines by RT-PCR, Western blotting and promoter transactivation assay. The JNK signaling and c-Jun activation were required to induce the HIF-1alpha gene transcription by LPS. The finding that a cascade transcriptional activation of distinct set of transcription factors, c-Jun and HIF-1alpha, in response to LPS stimulation associates with induction of TNFalpha gene transcription lends new insights into the functional mechanisms by which complex patterns of gene regulation on LPS-derived HIF activation are achieved.

Combination therapy with cyclosporine A and anti-TNF-alpha agents in the treatment of rheumatoid arthritis and concomitant hepatitis C virus infection

We describe two cases of rheumatoid arthritis (RA) patients and concomitant hepatitis C virus infection (HCV), treated with cyclosporine A (CsA) and anti-TNF-alpha agents. SGOT/SGPT and HCV-RNA serum levels remained unchanged longer than 1 year of treatment. No side effects were registered. We suggest that combination therapy with CsA and TNF-alpha blockers should be considered safe and well-tolerated in the treatment of HCV-positive RA patients.

Involvement of the PA28gamma-dependent pathway in insulin resistance induced by hepatitis C virus core protein

The hepatitis C virus (HCV) core protein is a component of nucleocapsids and a pathogenic factor for hepatitis C. Several epidemiological and experimental studies have suggested that HCV infection is associated with insulin resistance, leading to type 2 diabetes. We have previously reported that HCV core gene-transgenic (PA28gamma(+/+)CoreTg) mice develop marked insulin resistance and that the HCV core protein is degraded in the nucleus through a PA28gamma-dependent pathway. In this study, we examined whether PA28gamma is required for HCV core-induced insulin resistance in vivo. HCV core gene-transgenic mice lacking the PA28gamma gene (PA28gamma(-/-)CoreTg) were prepared by mating of PA28gamma(+/+)CoreTg with PA28gamma-knockout mice. Although there was no significant difference in the glucose tolerance test results among the mice, the insulin sensitivity in PA28gamma(-/-)CoreTg mice was recovered to a normal level in the insulin tolerance test. Tyrosine phosphorylation of insulin receptor substrate 1 (IRS1), production of IRS2, and phosphorylation of Akt were suppressed in the livers of PA28gamma(+/+)CoreTg mice in response to insulin stimulation, whereas they were restored in the livers of PA28gamma(-/-)CoreTg mice. Furthermore, activation of the tumor necrosis factor alpha promoter in human liver cell lines or mice by the HCV core protein was suppressed by the knockdown or knockout of the PA28gamma gene. These results suggest that the HCV core protein suppresses insulin signaling through a PA28gamma-dependent pathway.

[Risk of infection during treatment with tumor necrosis factor-alpha inhibitors]

Tumor necrosis factor-alpha (TNF) is essential for immune defense. TNF plays a major role in the recruitment of inflammatory cells to the site of infection and in the formation and maintenance of granulomas. In addition, it plays a primary and detrimental role in chronic autoimmune diseases. Drugs that inhibit TNF are effective in the treatment of inflammatory rheumatic and autoimmune diseases. However, the three currently available TNF antagonists (etanercept, infliximab and adalimumab) decrease host resistance to granulomatous diseases such as tuberculosis. The incidence of tuberculosis in patients treated with TNF antagonists is higher than in the general population. There are a number of case reports describing the association of TNF-antagonists and the presentation of other infectious diseases such as histoplasmosis, listeriosis, coccidioidomycosis, candidiasis and aspergillosis. These case reports, however, are anecdotal. Nonetheless, patients treated with TNF antagonists are immunocompromised and infectious diseases are most likely more frequent and may present differently than expected. In this review, we describe the role of TNF in constraining infectious diseases, the difference between the three available TNF antagonists, and we discuss the relevant clinical data published in the literature as related to the risk of anti-TNF therapy for infectious diseases.

Tumor necrosis factor-induced toxic liver injury results from JNK2-dependent activation of caspase-8 and the mitochondrial death pathway

In vitro studies of hepatocytes have implicated over-activation of c-Jun N-terminal kinase (JNK) signaling as a mechanism of tumor necrosis factor-alpha (TNF)-induced apoptosis. However, the functional significance of JNK activation and the role of specific JNK isoforms in TNF-induced hepatic apoptosis in vivo remain unclear. JNK1 and JNK2 function was, therefore, investigated in the TNF-dependent, galactosamine/lipopolysaccharide (GalN/LPS) model of liver injury. The toxin GalN converted LPS-induced JNK signaling from a transient to prolonged activation. Liver injury and mortality from GalN/LPS was equivalent in wild-type and jnk1-/- mice but markedly decreased in jnk2-/- mice. This effect was not secondary to down-regulation of TNF receptor 1 expression or TNF production. In the absence of jnk2, the caspase-dependent, TNF death pathway was blocked, as reflected by the failure of caspase-3 and -7 and poly(ADP-ribose) polymerase cleavage to occur. JNK2 was critical for activation of the mitochondrial death pathway, as in jnk2-/- mice Bid cleavage and mitochondrial translocation and cytochrome c release were markedly decreased. This effect was secondary to the failure of jnk2-/- mice to activate caspase-8. Liver injury and caspase activation were similarly decreased in jnk2 null mice after GalN/TNF treatment. Ablation of jnk2 did not inhibit GalN/LPS-induced c-Jun kinase activity, although activity was completely blocked in jnk1-/- mice. Toxic liver injury is, therefore, associated with JNK over-activation and mediated by JNK2 promotion of caspase-8 activation and the TNF mitochondrial death pathway through a mechanism independent of c-Jun kinase activity.

Proinflammatory cytokines, insulin resistance, and insulin secretion in chronic hepatitis C patients: A case-control study

OBJECTIVE

The purpose of this study was to explore the initial pathogenic mechanisms of diabetes associated with hepatitis C virus (HCV) infection.

RESEARCH DESIGN AND METHODS

Insulin resistance, proinflammatory cytokines, and beta-cell function were evaluated in a case-control study. A total of 28 consecutive nondiabetic patients with chronic hepatitis C were included in the study (anti-HCV+). Fourteen patients with chronic hepatitis other than HCV infection served as the control group (anti-HCV-). Both groups were closely matched by the main clinical variables associated with insulin resistance and the degree of liver fibrosis. In addition, there were no differences between groups regarding hepatic insulin extraction measured by calculating the ratio between C-peptide and insulin. Serum levels of proinflammatory cytokines (tumor necrosis factor [TNF]-alpha, soluble TNF receptor [sTNFR] 1, soluble TNFR2, and interleukin-6) were measured by enzyme-linked immunosorbent assay. Insulin resistance (homeostasis model assessment [HOMA] of insulin resistance [HOMA-IR]) and insulin secretion at baseline (HOMA-beta) and after various stimulus (oral glucose tolerance test, standard food intake, and intravenous glucagon) were determined by previously validated mathematic indexes.

RESULTS

HOMA-IR was higher in anti-HCV+ than in anti-HCV- patients (4.35 +/- 2.27 vs. 2.58 +/- 1.74; P = 0.01). All the proinflammatory cytokines analyzed were significantly higher in anti-HCV+ patients than in anti-HCV- patients. In addition, sTNFR1 and sTNFR2 were directly correlated to HOMA-IR. HOMA-beta as well as insulin and C-peptide responses after the intravenous glucagon test were significantly higher in anti-HCV+ patients than in anti-HC- patients.

CONCLUSIONS

Insulin resistance mediated by proinflammatory cytokines, but not a deficit in insulin secretion, could be the primary pathogenic mechanism involved in the development of diabetes associated with HCV infection.

Intrahepatic and peripheral T-cell responses in genotype 1b hepatitis C virus-infected patients with persistently normal and elevated aminotransferase levels

AIM

To evaluate whether the cytokine responses in liver and serum differ in chronic hepatitis C patients with normal and high alanine aminotransferase (ALT) levels.

METHODS

Thirty-three (16 with normal ALT level as group 1 and 17 with elevated ALT level as group 2) patients infected with genotype 1b hepatitis C virus (HCV) were examined. Liver infiltrating lymphomononuclear cells (LILMCs) were isolated from liver biopsy by collagenase type 1 and stimulated with phytohemagglutinin and interleukin 2 (IL-2). IL-10, IL-12, interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) were determined in serum and LILMCs by ELISA.

RESULTS

Serum cytokine levels were similar in both groups (P>0.05). Stimulated IFN-gamma and TNF-alpha levels in LILMCs were increased in both groups. IL-12 and IL-10 levels stimulated with IL-2 were higher in group 1 than in group 2 (P = 0.023). Histological activity index (HAI) and stage had a negative correlation with TNF-alpha and IFN-gamma levels in group 2.

CONCLUSION

Increased T-helper type 2 (Th2) cytokine response may regress inflammatory and biochemical activity. Progression of histological abnormalities in persons with elevated ALT probably depends on insufficient Th2 cytokine response, which does not balance Th1 cytokine response.

Weight loss during pegylated interferon and ribavirin treatment of chronic hepatitis C*

Treatment of hepatitis C virus (HCV) infection with interferon (IFN)-alpha, as monotherapy or in combination with ribavirin, is associated with significant side-effects including weight loss. The aim of our study was to describe the evolution of body weight during combination antiviral treatment and to examine the possible determinants of weight loss. This was a retrospective analysis of 126 patients who received combination therapy of pegylated IFN-alpha-2b and ribavirin at our unit. Body weight was recorded at each outpatient attendance during treatment and follow-up, and was expressed as a percentage of baseline value. We observed a decline of body weight during treatment. Median (range) weight values at 4, 12, 24, and 48 weeks (expressed as percentage of baseline weight) were 97.7 (91.5-110.2), 95.4 (84.4-109.4), 93.7 (80.8-106.5), and 91.1 (80.1-103.6) respectively. There was no significant association of increased weight loss with age, gender, pretreatment weight, ethnicity, pretreatment histological stage, cumulative IFN dose (adjusted for body weight), HCV genotype or treatment outcome. Median body weight returned to baseline within 6 months of stopping treatment. Patients experience significant weight loss during combination therapy. Those experiencing greater weight losses during therapy did not benefit from improved antiviral response.