Antiviral cell-mediated immune responses during hepatitis B and hepatitis C virus infections

A snapshot of virological presentation and outcome of immunosuppression-driven HBV reactivation from real clinical practice: Evidence of a relevant risk of death and evolution from silent to chronic infection

The study was undertaken in order to provide a snapshot from real clinical practice of virological presentation and outcome of patients developing immunosuppression-driven HBV reactivation. Seventy patients with HBV reactivation were included (66.2% treated with rituximab, 10% with corticosteroids and 23.8% with other immunosuppressive drugs). Following HBV reactivation, patients received anti-HBV treatment for a median (IQR) follow-up of 31(13-47) months. At baseline-screening, 72.9% of patients were HBsAg-negative and 27.1% HBsAg-positive. About 71.4% had a diagnosis of biochemical reactivation [median (IQR) HBV DNA and ALT: 6.9 (5.4-7.8) log IU/mL and 359 (102-775) U/L]. Moreover, 10% of patients died from hepatic failure. Antiviral prophylaxis was documented in 57.9% and 15.7% of HBsAg-positive and HBsAg-negative patients at baseline-screening (median [IQR] prophylaxis duration: 24[15-33] and 25[17-36] months, respectively). Notably, HBV reactivation occurred 2-24 months after completing the recommended course of anti-HBV prophylaxis in 35.3% of patients. By analysing treatment outcome, the cumulative probability of ALT normalization and of virological suppression was 97% and 69%, respectively. Nevertheless, in patients negative to HBsAg at baseline-screening, only 27% returned to HBsAg-negative status during prolonged follow-up, suggesting the establishment of chronic infection. In conclusion, most patients received a diagnosis of HBV reactivation accompanied by high ALT and 10% died for hepatic failure, supporting the importance of strict monitoring for an early HBV reactivation diagnosis. Furthermore, HBV reactivation correlates with high risk of HBV chronicity in patients negative for HBsAg at baseline-screening, converting a silent into a chronic infection, requiring long-term antiviral treatment. Finally, a relevant proportion of patients experienced HBV reactivation after completing the recommended course of anti-HBV prophylaxis, suggesting the need to reconsider proper duration of prophylaxis particularly in profound immunosuppression.

In HCV-related liver cirrhosis, local pulse wave velocity increases and in decompensated patients correlates with poorer survival

Background

Cirrhotic cardiomyopathy (CCM) refers to cardiac dysfunction in patients with liver cirrhosis, in the absence of other known cardiac disease.

Methods

Control group and patients diagnosed of liver cirrhosis without known cardiac disease or hepatocellular carcinoma were enrolled for this clinical observation study. Patients with diabetes mellitus, hypertension were excluded. Absolute global longitudinal strain, one-point carotid pulse wave velocity (one-point PWV) and various parameters were measured in resting status.

Results

There were 29 participants in the control group and 80 patients in the liver cirrhosis group. 27.8% of cirrhotic patients presented with normal systolic but abnormal diastolic functions and QTc prolongation that were compatible with CCM. 34.2% of cirrhotic patients presented with diastolic dysfunction in resting state comparing to 24.1% in control group. Systolic functions did not show conspicuous difference between cirrhosis and control group nor between compensated and decompensated cirrhosis, neither. Furthermore, one-point PWV was significantly higher in liver cirrhosis than in control group and higher in CCM than in non-CCM patients. One-point PWV predicted CCM and diastolic dysfunction in cirrhosis. Most importantly, its value > 1370cm/s predicted overall mortalities in decompensated cirrhosis (multivariable Cox analysis OR = 6.941) in addition to CTP score specifically in HCV related cirrhotic patients (AUC = 0.817).

Conclusions

In patients with cirrhosis, 27.8% were diagnosed with CCM by resting cardiovascular parameters. One-point PWV increased in CCM, correlated with diastolic dysfunction. It also correlated with overall mortality in patients with hepatitis C virus (HCV) related decompensated cirrhosis. Further study may be needed to confirm its capability for assessing CV and mortality risks in HCV related decompensated cirrhotic patients.

Prevention of liver tumor formation in woodchucks with established hepatocellular carcinoma by treatment with cationic liposome-DNA complexes

Background

Approximately 250 million people worldwide are chronically infected with hepatitis B virus (HBV) and more than half of the hepatocellular carcinoma (HCC) cases are attributed to this infection. As HCC has a high mortality rate, and current treatment options are remarkably limited, the development of new therapeutic treatment strategies is warranted.

Methods

In this study, woodchucks infected with woodchuck hepatitis virus (WHV), and with pre-existing liver tumors, were used as a model to investigate if complexes of cationic liposomes and non-coding DNA (JVRS-100) were effective in treatment of HCC.

Results

It was observed that the high serum viral load that is present in a typical chronic WHV infection (i.e., approximately 100-fold higher than human viral loads) results in immune suppression and resistance to treatment with JVRS-100. Treatment of woodchucks with lower serum viral load that more closely matched with the viral load usually seen in human HBV infection appears a better model for immunotherapeutic development based on the responsiveness to JVRS-100 treatment. In the latter case, marked declines in WHV DNA and WHV surface antigen were determined over the 12-week treatment period and WHV markers stayed suppressed during most time points of the 12-week follow-up period. Even more remarkably, the formation of new liver tumors was not observed in woodchucks treated with a well-tolerated dose of JVRS-100, as compared to several new tumors that developed in vehicle-treated control animals.

Conclusions

Although there was little decrease in the volumes of the liver tumors existing at the time of treatment, it is generally accepted that preventing the spread and metastasis of almost always fatal cancers such as HCC and thus, reducing it to a chronic and treatable disease can also be a successful therapeutic approach. The results in woodchucks warrant the investigation of JVRS-100 as an intervention to prevent liver cancer in patients chronically infected with HBV and at high risk for HCC development.

Interferon Gamma Gene Polymorphism (+874 T > A) and Chronic Hepatitis B in the Population of Gorgan, North-Eastern Iran

Background

Based on differences in individual immune responses to the hepatitis B virus (HBV), between 5% and 10% of patients become persistently infected with the virus, which leads to the determination of chronic HBV. Cytokines such as interferon gamma (IFN-γ) are secretory proteins that play important roles in both innate and adaptive immune responses. Functional studies have demonstrated that the IFN + 874A/T gene polymorphism can increase or decrease the overall expression of IFN-gamma (γ) and ultimately determine the outcome of the infection.

Objectives

This study was performed to investigate the relationship between the IFN-γ + 874 gene polymorphism and susceptibility to chronic HBV infection.

Methods

Polymorphism detection analysis was performed on 598 subjects from North-Eastern Iran. The IFN-γ gene polymorphism (+ 874A/T) was genotyped through a specific sequence primer polymerase chain reaction (SSP-PCR).

Results

The frequencies of the AA, AT, and TT genotypes were 31%, 51%, and 18% in the chronic HBV patient group, and 40%, 45%, and 15% in the healthy control group, respectively. However, a lack of association of the + 874 polymorphism in the IFN-γ gene of those with chronic HBV infection was found. Evaluation of HBV association with this polymorphism was significant under the dominant genetic model (P = 0.04).

Conclusions

Ultimately, no association could be characterized between the polymorphism in IFN-γ + 874A/T and susceptibility to chronic HBV infection in this segment of the Iranian population (P > 0.05).

Protective Efficacy of Nonpathogenic Nef-Deleted SHIV Vaccination Combined with Recombinant IFN-γ Administration against a Pathogenic SHIV Challenge in Rhesus Monkeys

We previously reported that a nef-deleted SHIV (SHIV-NI) is nonpathogenic and gave macaques protection from challenge infection with pathogenic SHIV-C2/1. To investigate whether IFN-gamma augments the immune response induced by this vaccination, we examined the antiviral and adjuvant effect of recombinant human IFN-gamma (rIFN-gamma) in vaccinated and unvaccinated monkeys. Nine monkeys were vaccinated with nef-deleted nonpathogenic SHIV-NI. Four of them were administered with rIFN-gamma and the other five monkeys were administered with placebo. After the challenge with pathogenic SHIV-C2/1, CD4(+) T-cell counts were maintained similarly in monkeys of both groups, while those of the unvaccinated monkeys decreased dramatically at 2 weeks after challenge. However, the peaks of plasma viral load were reduced to 100-fold in SHIV-NI vaccinated monkeys combined with rIFN-gamma compared with those in SHIV-NI vaccinated monkeys without rIFN-gamma. The peaks of plasma viral load were inversely correlated with the number of SIV Gag-specific IFN-gamma-producing cells. In SHIV-NI-vaccinated monkeys with rIFN-gamma, the number of SIV Gag-specific IFN-gamma-producing cells of PBMCs increased 2-fold compared with those in SHIV-NI-vaccinated monkeys without rIFN-gamma, and the NK activity and MIP-1alpha production of PBMCs were also enhanced. Thus, vaccination of SHIV-NI in combination with rIFN-gamma was more effective in modulating the antiviral immune system into a Th1 type response than SHIV-NI vaccination alone. These results suggest that IFN-gamma augmented the anti-viral effect by enhancing innate immunity and shifting the immune response to Th1.

Modulation of regulatory T-cell activity in combination with interleukin-12 increases hepatic tolerogenicity in woodchucks with chronic hepatitis B

Regulatory T cells (Treg) play a critical role in the modulation of immune responses to viral antigens in chronic viral hepatitis. Woodchucks (Marmota monax) infected with the woodchuck hepatitis virus (WHV) represent the best animal model for chronic hepatitis B virus (HBV) infection. Examination of intrahepatic and peripheral Treg in uninfected and WHV chronically infected woodchucks showed a significant increase of intrahepatic Treg numbers in chronically infected animals, whereas no differences were found in peripheral blood. In agreement with these data, higher expression levels of Forkhead box P3 (Foxp3), interleukin (IL)-10, transforming growth factor beta (TGF-β) were detected in the liver of chronic WHV carriers in comparison to uninfected animals. Furthermore, treatment of WHV-infected animals with an adenovirus encoding IL-12 failed to reduce viral load, a finding that was associated with lymphocyte unresponsiveness to IL-12 stimulation in vitro. We observed that TGF-β and Treg play a major role in the lack of lymphocyte response to IL-12 stimulation, as TGF-β inhibition and Treg depletion allowed recovery of T-cell responsiveness to this cytokine. Based on these results, woodchucks were treated with IL-12 in combination with a TGF-β inhibitory peptide or Treg depletion. However, no antiviral effect was achieved and, instead, an enhancement of the intrahepatic tolerogenic environment was observed.

CONCLUSION

Our data show that TGF-β inhibition or Treg depletion had no added benefit over IL-12 therapy in chronic WHV infection. IL-12 immunostimulation induces a strong immunosuppressive reaction in the liver of chronic WHV carriers that counteracts the antiviral effect of the treatment.

TNF-α -863 polymorphisms and the risk of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common type of highly malignant tumor. Guangxi is an area of China characterized by a high incidence of HCC. Previous epidemiological studies have found that chronic infection with hepatitis B virus (HBV) is one of the major etiological risk factors for HCC in China. With the increased understanding of the host immune response against HBV and the pathogenesis of the virus, at present, greater attention is being given to the immune response of cytokine genes, as polymorphisms may have a major impact on the course and outcome of HBV infection. In the present study, we genotyped tumor necrosis factor-α (TNF-α) rs1800629 (-308G/A), rs1800630 (-863C/A); interleukin-1B rs1143627 (-31T/C); and transforming growth factor β1 (TGF-β1) rs1800469 (-509C/T) in a hospital-based study of 772 HCC cases and 852 cancer-free controls. The distribution of the frequency of TNF-α rs1800630 sites of CC, CA, AA were 65.67, 27.46 and 6.87% in the case group, respectively, as compared with 67.02, 29.58 and 3.40% in the controls, all with a statistical significance (P<0.05). The logistic regression analysis revealed that the variant rs1800630 AA genotypes were associated with a significantly increasing risk of HCC (OR=2.058, 95% CI 1.289-3.287), compared with the wild-type rs1800630 CC. Further stratified analyses showed that after stratification for history of alcohol drinking, in a subgroup of individuals without a history of drinking, the HCC risk in the group with the TNF-α rs1800630 A allele was 1.839 times higher than that in the group with TNF-α rs1800630 C (P<0.010). These findings suggest that TNF-α rs1800630 may contribute to the risk of HCC, however, these data require further validation.

Relationship between T-lymphocyte cytokine levels and sero-response to hepatitis B vaccines

AIM: To investigate the cellular defects by analyzing the (Th1/Th2) cytokine levels in vaccine responders and non-responders.

METHODS: Peripheral blood mononuclear cell (PBMC) from responders and non-responders were stimulated with or with out recombinant HBsAg or PHA. Broad spectrum of cytokines viz (Th1) IFN-γ, IL-2, TNF-α, IL-12 and (Th2) IL-10, IL-4 were measured after in vitro stimulation with recombinant HBsAg and were compared with respective antibody titers.

RESULTS: A significant decrease (P = 0.001) in Th1 and Th2 cytokines namely, IL-2, INF-γ, TNF-α and IL-10 in non-responders was observed. The level of IL-4 was not significant between the three groups. Furthermore, despite a strong Th1 and Th2 cytokine response, the level of IL-12 was elevated in high-responders compared to other groups (P = 0.001) and demonstrated a positive correlation with anti-HBs titers and Th1 cytokine response.

CONCLUSION: Our findings suggest that unresponsiveness to recombinant hepatitis B vaccines (rHB) is multifactorial, including specific failure of antigen presentation or the lack of both T helper Th1 and Th2 response.

Epidemiology of hepatitis B, C, D and G viruses and cytokine levels among intravenous drug users

To investigate the features of various hepatitis virus infection in intravenous drug users (IVDU), we conducted an epidemiological survey of hepatitis viruses including hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV) and hepatitis G virus (HGV) in IVDU. The correlation of TH lymphocyte cytokine and hepatitis virus infection was examined. A study population of 406 IVDU consisted of 383 males and 23 females. HBV-DNA and HCV-RNA were detected by fluorescence quantitative polymerase chain reaction. HBsAg, HBeAg, anti-HBc, anti-HCV, HDV-Ag and anti-HGV were assayed by ELISA. The levels of cytokines of TH1 and TH2 were measured by ELISA. The similar indices taken from 102 healthy persons served as controls. The infection rate of each virus among IVDU was 36.45 % for HBV, 69.7 % for HCV, 2.22 % for HDV, and 1.97 % for HGV, respectively. The co-infection rate of HBV and HCV was detected in 113 of 406 (27.83 %). In contrast, among controls, the infection rate was 17.65 % for HBV and 0 % for the other hepatitis viruses. The levels of PHA-induced cytokines (IFN-gamma and IL-4) and the level of serum IL-2 were obviously decreased in IVDU. On the other hand, the level of serum IL-4 was increased. The IFN-gamma level was continuously decreased when the IVDU was infected with HBV/HCV. In conclusion, HBV and HCV infection were common in this population of IVDU and they had led to a high incidence of impaired TH1 cytokine levels.

Association analysis of hepatitis virus B infection with haplotypes of the TBX21 gene promoter region in the Chinese population

BACKGROUND

The T-box21 (TBX21) gene encodes the transcription factor T-bet (T-box expressed in T-cells), which influences naive T-lymphocyte development and has been implicated in the pathogenesis of many diseases.

METHODS

We selected 208 hepatitis B patients and 213 healthy volunteers to examine whether polymorphisms or haplotypes of the TBX21 gene promoter were associated with hepatitis B virus (HBV) infection in the Chinese population. Two polymorphisms at -1499 and -1514 located in the TBX21 promoter region were identified by the PCR-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

Single nucleotide polymorphism (SNP) at -1499 was significantly different between HBV patients and healthy controls [p=0.003; odds ratio (OR) 3.65, 95% confidence interval (CI) 1.58-8.45]. Similarly, our results showed a significantly higher level of haplotype D (--/AC) in HBV patients compared to control subjects (p=0.005; OR 4.82, 95% CI 1.59-14.61).

CONCLUSIONS

Based on our findings, it seems that genetic variations of allele -1499 and haplotype D (--/AC) within the TBX21 promoter region contribute to susceptibility to HBV infection in the Chinese population.

Hepatitis B virus seropositivity is not associated with increased risk of carotid atherosclerosis in Taiwanese

BACKGROUND

Chronic infection has been proposed to increase the risk of atherosclerosis in several experimental and epidemiological studies. However, the relationship of chronic hepatitis B virus (HBV) infection and atherosclerosis remains controversial. We conducted this cross-sectional study to evaluate the association of carotid atherosclerosis with hepatitis B seropositivity.

METHODS AND RESULTS

In this cross-sectional study, we collected data from subjects undergoing health examination, including B-mode carotid ultrasonography, hepatitis B surface antigen (HBsAg) status and assessment of traditional cardiovascular risk factors, at our institutes in Taiwan between 2002 and 2003. Cases with chronic hepatitis C had been excluded. Of the 508 eligible subjects, 87 (17.1%) were positive for HBsAg and only six of them were positive for HBeAg. Compared with HBsAg negative subjects, the ORs (and 95% CIs) for the subjects with chronic hepatitis B to have carotid atherosclerosis were 1.24 (0.73-2.10) indexed by the presence of carotid atherosclerotic plaque (Intima-media thickness, IMT>or=1.3mm), 0.74 (0.38-1.42) by maximal common carotid artery IMT>or=75th percentile, and 1.09 (0.62-1.90) by extracranial carotid artery atherosclerotic score>or=2, with the use of multivariate logistic regression analyses.

CONCLUSION

Hepatitis B virus seropositivity was not associated with an increased severity of carotid atherosclerosis in Taiwanese.

Association of the -183 polymorphism in the IFN-gamma gene promoter with hepatitis B virus infection in the Chinese population

Interferon-gamma (IFN-gamma) is a pleiotropic cytokine that plays an important role in regulating cellular immune responses. Regulation of IFN-gamma expression is considered to be strictly controlled at the transcriptional level. Two single-nucleotide polymorphisms (SNPs) within the human IFN-gamma promoter (at positions -183 and -155) are considered to influence the promoter activity by altering the acting transcription factor-1 (AP-1) binding. We sought to assess the association between the SNPs of the IFN-gamma promoter and the host susceptibility to hepatitis B virus (HBV) infection, as well as its interaction with age and gender. No polymorphism at position-155 was detected in any of the participants, but a significant difference was found in the polymorphism at position -183 between the cases and controls (G/T and T/T vs. GG; P < 0.01, odds ratio (OR) = 4.50 (95% confidence interval (CI) = 2.23-9.09). A susceptibility analysis revealed a gradually increased trend of the OR value from the young to the old group (OR = 3.03, 4.17, and 5.56). Similarly, the association of the -183 polymorphism was markedly different in females (OR = 5.71). Our data suggest that the polymorphism at position -183 of the IFN-gamma gene promoter may be associated with susceptibility to HBV infection, and age and gender factors are coordinative risk factors.

Predominance of type 1 (Th1) cytokine production in the liver of patients with HCV-associated mixed cryoglobulinemia vasculitis

BACKGROUND/AIMS

Patients with hepatitis C virus (HCV) mixed cryoglobulinemia (MC) vasculitis have a higher mortality rate and more frequent incidence of cirrhosis than their cryoglobulin-negative counterparts. To compare the cytokine profile of liver-infiltrating T cells in HCV-infected patients with or without MC vasculitis.

METHODS

Hepatic biopsy specimens were obtained from HCV infected patients with and without MC vasculitis. Using intracellular staining and flow cytometry, we assessed the ability of freshly isolated liver T cells from these biopsies to produce IFN-gamma, TNF-alpha, IL-2, IL-4, and IL-10 in response to stimulation with PMA and ionomycin.

RESULTS

HCV-MC vasculitis patients compared to HCV-MC negative controls have an enhanced hepatic T cells production of Th1-type cytokines [i.e. TNF-alpha(30.3 +/- 13% vs. 15.5 +/- 5%, P = 0.01), IL-2 (20.2 +/- 9% vs. 10 +/- 4%, P = 0.01) and IFN-gamma (22.2 +/- 11% vs. 9.4 +/- 4%, P = 0.008)], whereas IL-10, a representative Th2-type cytokine, was significantly lower (7.2 +/- 4% vs. 17 +/- 7%, P = 0.01).

CONCLUSIONS

T cell from the liver of HCV-MC vasculitis patients display a significantly augmented liver Th1 profile compared to MC-negative controls. This enhanced production of type-1 cytokines may account for a more severe course of liver disease.

A consecutive priming-boosting vaccination of mice with simian immunodeficiency virus (SIV) gag/pol DNA and recombinant vaccinia virus strain DIs elicits effective anti-SIV immunity

To evaluate immunity induced by a novel DNA prime-boost regimen, we constructed a DNA plasmid encoding the gag and pol genes from simian immunodeficiency virus (SIV) (SIVgag/pol DNA), in addition to a replication-deficient vaccinia virus strain DIs recombinant expressing SIV gag and pol genes (rDIsSIVgag/pol). In mice, priming with SIVgag/pol DNA, followed by rDIsSIVgag/pol induced an SIV-specific lymphoproliferative response that was mediated by a CD4+-T-lymphocyte subset. Immunization with either vaccine alone was insufficient to induce high levels of proliferation or Th1 responses in the animals. The prime-boost regimen also induced SIV Gag-specific cellular responses based on gamma interferon secretion, as well as cytotoxic-T-lymphocyte responses. Thus, the regimen of DNA priming and recombinant DIs boosting induced Th1-type cell-mediated immunity, which was associated with resistance to viral challenge with wild-type vaccinia virus expressing SIVgag/pol, suggesting that this new regimen may hold promise as a safe and effective vaccine against human immunodeficiency virus type 1.

Induction of hepatitis C virus-specific humoral and cellular immune responses in mice and rhesus by artificial multiple epitopes sequence

The investigation of antigenic epitopes in hepatitis C virus (HCV) protein suggests that a central sequence combined with multiple antigenic epitopes of HCV might be significant as a potential vaccine candidate. This artificial sequence of combined and modified multiple antigenic epitopic peptides (Hc-B2), containing three B and four T cell epitopes, was constructed and expressed in E. coli. Antigen analysis indicated that this peptide antigen was capable of interacting with anti-sera collected from hepatitis C patients infected by three genotypes of HCV from three different geographic areas of China, respectively. The immunological analysis of this peptide antigen in mice and rhesus suggested that its immunogenicity was effective. However, a complete evaluation of this peptide could not be made as an effective animal model for HCV infection (such as in the chimpanzee) was not available for this study.

Enhanced monocyte Th1 cytokine production in HCV-infected cryoglobulinemic patients

BACKGROUND/AIMS

The etiologic link between chronic hepatitis C virus (HCV) infection and mixed cryoglobulinemia is well established, while its prognostic significance within the context of HCV-related hepatitis is not as clear. Patients with an HCV-related cryoglobulinemic syndrome oft have mild liver disease, an aspect that can be influenced by an individual's Th1/Th2 orientation. Our goal was to document stigmata of differentiate cytokine production in this subgroup of patients.

METHODS

Fifteen patients with chronic HCV-related liver disease (CLD) and a cryoglobulinemic syndrome (CRYO) were compared to age/sex matched CLD controls with negative cryocrit. Cultured monocytes were stimulated with either Staphylococcus aureus (SAC) or lipopolysaccharide (LPS).

RESULTS

The protein concentrations of TNF-alpha and of the Th1-type cytokines interleukin (IL)-12 and IL-18 were significantly greater in the CRYO group, while IL-10 (a Th2 cytokine) levels were greater in the control group.

CONCLUSIONS

The clinical distinctiveness of the two groups was reflected at the cytokine level. The cryoglobulinemic patients studied showed a greater Th1 polarization than their cryoglobulin-negative counterparts. This enhanced production of Th1-type cytokines is seemingly not able to rid the host of infection but may account for a milder course of liver disease.

Rheumatoid factors: host resistance or autoimmunity?

Rheumatoid factors (RFs), autoantibodies that bind to the Fc portion of IgG, are important in the immune response. RF-committed B-cells exist in the circulating lymphocyte pool in a high frequency (approximately 1-2 %) in normal individuals and in patients with pathological conditions associated with the sustained levels of circulating RF, such as rheumatoid arthritis (RA), Sjogren's syndrome (SS), and mixed cryoglobulinemia, associated with hepatitis C virus infection. RFs are induced by many infectious entities (viruses, bacteria, parasites) as a consequence of a secondary immune response to the pathogen, but usually the response is transient. It is likely that RFs play an important role in the host's defense against infection, both at the cellular level, where the RF B-cell can be an antigen presenting cell which can promote the antipathogen response, and at the humoral level, where RFs can contribute to the mopping up of the IgG antipathogen antibodies by contributing to immune complex formation and clearance. There has been much research on RFs in chronic pathological conditions, and the literature pertaining to their origin, structure, binding specificities, and possible roles in disease are discussed. The importance of the host defense, sometimes at the expense of an autoimmune response, is a balance that needs to be considered in light of a possible outcome of health or disease.

In situ expression of Granzyme B and Fas-ligand in the liver of viral hepatitis

BACKGROUND/AIMS

The molecular mechanism involved in hepatocellular injury in viral hepatitis remains to be clarified.

METHODS

We investigated the in situ expression of effector molecules of cytotoxic T lymphocytes such as Fas-ligand (Fas-L), perforin and Granzyme B (Gr-B) immunohistochemically in liver tissues from 20 patients with chronic hepatitis B (CHB) and C (CHC). The degree of cell infiltration was analysed semi-quantitatively and compared with the histological activity index (HAI). Fas-L was expressed in both CD4 and CD8 T-cells in the portal tract as well as in the parenchyma.

RESULTS

Immunostaining of serial sections demonstrated that mononuclear cells at interface hepatitis and focal necrosis were mainly Fas-L positive CD8 T-cells. On the other hand, the expression of perforin or Gr-B was limited to a few mononuclear cells in the portal tract and parenchyma. Semi-quantitative analysis showed a positive correlation between HAI and the grade of infiltration of CD8 T-cells or Fas-L-positive cells, while the correlation was not apparent between HAI and the number of Gr-B positive cells. The expression of these molecules was not different between types of viruses.

CONCLUSIONS

These results suggest that Fas-L-positive CD8 T-cells play a major role in the pathogenesis of liver cell injury in chronic hepatitis.

Diminished Th1 and Th2 cytokine production in healthy adult nonresponders to recombinant hepatitis B vaccine

Vaccination of healthy adults with recombinant hepatitis B (rHB) vaccine fails to induce a protective antibody response in a proportion of individuals. Imbalanced T-helper (Th)1/Th2 response has been attributed to the lack of specific antibody response to rHB vaccine. In this study, in vitro production of interleukin (IL)-2, interferon (IFN)-gamma and IL-10 was investigated in Iranian healthy adults vaccinated with rHB vaccine. Peripheral blood mononuclear cells (PBMC) were isolated from 18 high responders and eight nonresponders and stimulated with rHB antigen or phytohaemaglutinin (PHA) mitogen. The cytokines were quantitated in culture supernatants by sandwich enzyme-linked immunosorbent assay (ELISA). Our results demonstrated a significant decrease in the production of IL-2, IFN-gamma and IL-10 (P < 0.005) in response to rHB antigen. The levels of all cytokines induced by PHA were similarly represented in both groups of vaccinees. These findings suggest that unresponsiveness to rHB vaccine may be owing to inadequate Th1- and Th2-like cytokine production.

Cytokine serum levels in patients with chronic HCV infection

The pathogenic role of immune-mediated mechanisms in chronic hepatitis C virus (HCV) infection has not yet been elucidated. In this study, we report different cytokine expression profiles from hemodialysis (HD) and non-HD HCV (+) patients. IL-1beta, IL-2, IL-4, IL-6, TNF-alpha, and TGF-beta1 serum levels, and liver biochemical parameters were determined in 85 individuals (41 HD patients and 44 non-HD patients). Screening for HCV RNA and anti-HCV antibodies was performed using qualitative and quantitative reverse transcription polymerase chain reaction (RT-PCR), and standardized enzyme-linked immunosorbent assay (ELISA) and recombinant immunoblot assay (RIBA) methods, respectively. IL-4 and IL-1beta demonstrated decreased serum levels in non-HD HCV carriers compared with healthy controls. Both T helper (Th) 1 and Th2 lymphocytes were highly associated with chronic HCV infection, as indicated by the increased IL-2, IL-4, and IL-6 cytokine circulating levels in all chronic active hepatitis (CAH) patients examined. An enhanced Th2 response (IL-4 and IL-6) coupled with increased TNF-alpha and IL-1beta serum levels was reported in HD HCV (-) patients. In conclusion, our data show that a virus-induced Th2 and IL-1beta immunosuppression is an early event in HCV-related chronicity. Long-term HD specifically exerts a chronic effect on IL-6, IL-1beta, and TNF-alpha serum circulating levels. Irrespective of the HD status, HCV viremia, and liver biochemistry parameters, both Th1 and Th2 responses are highly associated with chronic HCV infection.

Viral escape mechanisms--escapology taught by viruses

Viruses have 'studied' immunology over millions of years of coevolution with their hosts. During this ongoing education they have developed countless mechanisms to escape from the host's immune system. To illustrate the most common strategies of viral immune escape we have focused on two murine models of persistent infection, lymphocytic choriomeningitis virus (LCMV) and murine cytomegalovirus (MCMV). LCMV is a fast replicating small RNA virus with a genome prone to mutations. Therefore, LCMV escapes from the immune system mainly by two strategies: 'speed' and 'shape change'. At the opposite extreme, MCMV is a large, complex DNA virus with a more rigid genome and thus the strategies used by LCMV are no option. However, MCMV has the coding capacity for additional genes which interfere specifically with the immune response of the host. These escape strategies have been described as 'camouflage' and 'sabotage'. Using these simple concepts we describe the spectrum of viral escapology, giving credit not only to the researchers who uncovered this fascinating area of immunology but also to the viruses themselves, who still have a few lessons to teach.

Enhancement of immunoglobulin G2a and cytotoxic T-lymphocyte responses by a booster immunization with recombinant hepatitis C virus E2 protein in E2 DNA-primed mice

The induction of strong cytotoxic T-lymphocyte (CTL) and humoral responses appear to be essential for the elimination of persistently infecting viruses, such as hepatitis C virus (HCV). Here, we tested several vaccine regimens and demonstrate that a combined vaccine regimen, consisting of HCV E2 DNA priming and boosting with recombinant E2 protein, induces the strongest immune responses to HCV E2 protein. This combined vaccine regimen augments E2-specific immunoglobulin G2a (IgG2a) and CD8(+) CTL responses to a greater extent than immunizations with recombinant E2 protein and E2 DNA alone, respectively. In addition, the data showed that a protein boost following one DNA priming was also effective, but much less so than those following two DNA primings. These data indicate that sufficient DNA priming is essential for the enhancement of DNA encoded antigen-specific immunity by a booster immunization with recombinant E2 protein. Furthermore, the enhanced CD8(+) CTL and IgG2a responses induced by our combined vaccine regimens are closely associated with the protection of BALB/c mice from challenge with modified CT26 tumor cells expressing HCV E2 protein. Together, our results provide important implications for vaccine development for many pathogens, including HCV, which require strong antibody and CTL responses.