Detection of type 2-like T-helper cells in hepatitis C virus infection: implications for hepatitis C virus chronicity

Determinants of viral clearance and persistence during acute hepatitis C virus infection

The virological and immunological features of hepatitis C virus (HCV) infection were studied weekly for 6 months after accidental needlestick exposure in five health care workers, four of whom developed acute hepatitis that progressed to chronicity while one subject cleared the virus. In all subjects, viremia was first detectable within 1-2 weeks of inoculation, 1 month or more before the appearance of virus-specific T cells. The subject who cleared the virus experienced a prolonged episode of acute hepatitis that coincided with a CD38+ IFN-gamma- CD8+ T cell response to HCV and a small reduction in viremia. Subsequently, a strong CD4+ T cell response emerged and the CD8+ T cells became CD38- and started producing IFN-gamma in response to HCV, coinciding with a rapid 100,000-fold decrease in viremia that occurred without a corresponding surge of disease activity. Chronic infection developed in two subjects who failed to produce a significant T cell response and in two other subjects who initially mounted strong CD4+ T cell responses that ultimately waned. In all subjects, viremia was higher at the peak of acute hepatitis than it was when the disease began, and the disease improved during the viremia. These results provide the first insight into the host-virus relationship in humans during the incubation phase of acute HCV infection, and they provide the only insight to date into the virological and immunological characteristics of clinically asymptomatic acute HCV infection, the commonest manifestation of this disease. In addition, the results suggest that the vigor and quality of the antiviral T cell response determines the outcome of acute HCV infection, that the ability of HCV to outpace the T cell response may contribute to its tendency to persist; that the onset of hepatitis coincides with the onset of the CD8+ T cell response, that disease pathogenesis and viral clearance are mediated by different CD8+ T cell populations that control HCV by both cytolytic and noncytolytic mechanisms, and that there are different pathways to viral persistence in asymptomatic and symptomatic acute HCV infection.

Hepatitis C virus core protein inhibits human T lymphocyte responses by a complement-dependent regulatory pathway

Complement proteins are involved in early innate immune responses against pathogens and play a role in clearing circulating viral Ags from the blood of infected hosts. We have previously demonstrated that hepatitis C virus (HCV) core, the first protein to be expressed and circulating in the blood of infected individuals, inhibited human T cell proliferative response through interaction with the complement receptor, globular domain of C1q receptor (gC1qR). To investigate the mechanisms of HCV core/gC1qR-induced inhibition of T cell proliferation, we examined the effect of core protein on the early events in T cell activation. We found that HCV core inhibited phosphorylation of extracellular signal-regulated kinase (ERK) and mitogen-activated ERK kinase (MEK). HCV core-induced impairment of ERK/MEK mitogen-activated protein kinase resulted in the inhibition of IL-2 and IL-2Ralpha gene transcription, which led to the inhibition of IL-2 production and high-affinity IL-2R expression. Importantly, the ability of anti-gC1qR Ab treatment to reverse HCV core-induced inhibition of ERK/MEK phosphorylation reveals that the interaction between HCV core and gC1qR is linked to the interference of ERK/MEK mitogen-activated protein kinase activation. These results imply that HCV core-induced blockage of intracellular events in T cell activation by a complement-dependent regulatory pathway may play a critical role in the establishment of HCV persistence during the acute phase of viral infection.

The immunopathogenesis of hepatitis C virus infection

The outcome of HCV infection is determined by the interaction between the virus and the host immune system. The persistence of infection in most HCV-infected individuals, despite the presence of HCV-directed antibodies, suggests that such antibodies fail to induce viral clearance. Patients with self-limited hepatitis C have evidence of a polyclonal, multispecific CD8+ T-cell response along with a coordinated CD4+ T-cell response that is associated with eradication of HCV infection. Cytokines are produced both locally within the liver and systemically and may play an important role in controlling viral replication and contributing to hepatocellular damage through amplification of a nonspecific immune response. In most patients, the humoral, cellular immune, and cytokine response seem insufficient to eradicate infection. In its attempt to clear the virus from the liver, the immune system contributes to the hepatocellular injury seem in most chronically infected patients. A better understanding of the host's immune response may provide further insight on the pathogenetic mechanisms involved in development of chronic hepatitis and aid the development of better therapeutic strategies.

Interleukin-12 in the treatment of chronic hepatitis B and C

Interleukin-12 plays a central role in mounting an effective cellular immune response directed towards elimination of intracellular pathogens. In two open label, multicenter, dose-escalation phase I/II studies tolerability, pharmacokinetics, pharmacodynamics, and efficacy of subcutaneously administered recombinant human interleukin-12 (rHuIL-12) was assessed in the treatment of chronic hepatitis B and C. Forty-six patients with chronic hepatitis B and 60 patients with chronic hepatitis C were treated for 12 and 10 consecutive weeks, respectively. rHuIL-12 was generally well tolerated, but was associated with temporary decreases in neutrophils and lymphocyte counts, and with elevations in serum transaminases and bilirubin. Serum IL-12 levels observed were higher at 0.5 microg/kg compared with 0.25 microg/kg doses, suggesting a dose-related increase in systemic exposure of IL-12. Measurable levels of interferon-gamma were also observed at the highest dose of 0.5 microg/kg. At the end of treatment HBV DNA clearance was greater in patients treated with 0.50 microg/kg (25%) or with 0.25 microg/kg (13%) compared with those given 0.03 microg/kg. In patients with chronic hepatitis C, HCV RNA remained detectable in all patients. A more than 50% decrease in pretreatment HCV RNA levels was observed in 3/16 patients (0.03 microg/kg), in 3/14 (0.10 microg/kg), in 6/15 (0.25 microg/kg), and in 8/15 patients of the 0.5 microg/kg dose group. In conclusion, antiviral activity of rHuIL-12 in patients with chronic hepatitis B or C does not appear to be advantageous in comparison to other currently available treatments.

T-Cell immune activation in children with vertically transmitted hepatitis C virus infection

Little is known concerning the clinical features, the histological outcome, and the effects on the maturation of immune system of children with vertically-transmitted hepatitis C virus (HCV) infection. Specifically, no data are available on the peripheral distribution of T-cell subsets. The frequency of naive and memory cells, activated T cells, and cytokine-producing T cells was analyzed in nine HCV-infected children born to HCV-positive mothers. In HCV-infected children, the distribution of naive and memory cells was not significantly altered in the CD4 subset whereas within the CD8 subset, an increase of memory and a decrease of naive cells was observed. The frequency of HLA-DR-positive and Fas-positive T cells was increased in HCV-infected children in both CD4 and CD8 subsets. The distribution of Fas-expressing T cells was directly related to that of HLA-DR cells and inversely related to the frequency of naive T cells. In regard with cytokine production we found increased levels of both CD4 and CD8 interferon-gamma (IFN-gamma)-producing cells whereas no difference in the percentage of interleukin-2 (IL-2)-producing T cells was observed. No meaningful correlation was observed between individual T cell subsets and ALT levels or HCV viral load. In conclusion, our results indicate an increased T-cell activation and a shift to a T(H)1 pattern of cytokine production in children with vertically transmitted HCV infection. The cause of this kind of immune response could reside in the persistent antigenic stimulation by chronic HCV infection.

Mechanisms of action of ribavirin in antiviral therapies

Although ribavirin was originally synthesized over 30 years ago and has been used to treat viral infections as monotherapy (respiratory syncytial virus and Lassa fever virus) or with interferon-alpha (IFN-alpha) as combination therapy (hepatitis C virus), the precise mechanism of its therapeutic activities remains controversial. In this review we focus on two main biological properties of ribavirin: its indirect and direct antiviral activities (with particular emphasis on its efficacy against chronic hepatitis C infection). Each property could individually or collectively account for its clinical efficacy against viral infections. First, with emphasis on the evidence for indirect activities of ribavirin, we will review the clinical observations that suggest that the immunomodulatory properties of ribavirin can in part account for its antiviral activities in vivo. We will then describe the mode of ribavirin's direct antiviral activities. These direct activities can be ascribed to several possible mechanisms, including the recently described activity as an RNA mutagen, a property that may be important in driving a rapidly mutating RNA virus over the threshold to 'error catastrophe'.

Acute hepatitis C without and with schistosomiasis: correlation with hepatitis C-specific CD4(+) T-cell and cytokine response

BACKGROUND & AIMS

Immune responses during the first few months of acute hepatitis C virus (HCV) infection seem crucial for viral control, but the relationship of these responses to natural history is poorly characterized.

METHODS

This prospective study investigated the HCV-specific CD4(+) and cytokine responses in patients with acute HCV hepatitis with or without Schistosoma mansoni coinfection, a parasitic infection with T helper (Th) 2 immune bias. HCV-specific CD4(+) proliferative responses and cytokine production in peripheral blood mononuclear cells were correlated with liver biopsy results at 6 months and at the end of follow-up.

RESULTS

Whereas 5 of 15 patients with HCV alone recovered from acute HCV, all (17 of 17) patients with S. mansoni coinfection progressed to histologically proven chronic hepatitis. Coinfected patients had either absent or transient weak HCV-specific CD4(+) responses with Th0/Th2 cytokine production. The magnitude of the HCV-specific CD4(+) response at week 12 was inversely correlated with the fibrosis progression rate in chronically infected patients.

CONCLUSIONS

Patients with acute hepatitis C and schistosomiasis coinfection cannot clear viremia and show rapid progression once chronic infection is established. This rapid progression is associated with a strong Th2 response in peripheral immune responses, suggesting that early development of vigorous Th1 responses not only facilitates clearance but delays disease progression.

Experimental and emerging therapies for chronic hepatitis C virus infection

Hepatitis C virus infection is prevalent throughout the world and is associated with substantial morbidity, mortality and health economic burden. No effective preventative measure, including vaccination, is currently available. Incremental and substantial progress in the rate of viral eradication using interferon-based therapies has been made over the past decade. The most recent advance has been related to the development of a pegylated form of IFN-alpha by two independent pharmaceutical companies. Pegylation of IFN-alpha appears to prolong its half-life, allowing for less frequent dosing. Reports have suggested that pegylated interferons are also associated with better efficacy for viral eradication in patients with hepatitis C virus. Slower progress also has been made in developing non-interferon-based therapeutic agents against hepatitis C virus, including protease inhibitors, helicase inhibitors, ribozymes, antisense therapies, cytokine-based therapies and T-cell-based therapeutic vaccines.

The chimpanzee model of hepatitis C virus infections

The chimpanzee (Pan troglodytes) is the only experimental animal susceptible to infection with hepatitis C virus (HCV). The chimpanzee model of HCV infection was instrumental in the initial studies on non-A, non-B hepatitis, including observations on the clinical course of infection, determination of the physical properties of the virus, and eventual cloning of the HCV nucleic acid. This review focuses on more recent aspects of the use of the chimpanzee in HCV research. The chimpanzee model has been critical for the analysis of early events in HCV infection because it represents a population for which samples are available from the time of exposure and all exposed animals are examined. For this reason, the chimpanzee represents a truly nonselected population. In contrast, human cohorts are often selected for disease status or antibody reactivity and typically include individuals that have been infected for decades. The chimpanzee model is essential to an improved understanding of the factors involved in viral clearance, analysis of the immune response to infection, and the development of vaccines. The development of infectious cDNA clones of HCV was dependent on the use of chimpanzees, and they will continue to be needed in the use of reverse genetics to evaluate critical sequences for viral replication. In addition, chimpanzees have been used in conjunction with DNA microarray technology to probe the entire spectrum of changes in liver gene expression during the course of HCV infection. The chimpanzee will continue to provide a critical aspect to the understanding of HCV disease and the development of therapeutic modalities.

Quantitative analysis of specific Th1/Th2 helper cell responses and IgG subtype antibodies in interferon-alpha-treated patients with chronic hepatitis C

This study aimed to characterise the immune mechanisms relevant to viral clearance in interferon (IFN)-alpha-treated chronic hepatitis C virus (HCV) infection. Proliferative responses of peripheral blood mononuclear cells from sustained complete IFN-alpha therapy responders (n = 8), nonresponders (n = 13), untreated patients (n = 10), and healthy controls (n = 5) were measured retrospectively upon stimulation with recombinant HCV-antigens (core, helicase, NS3, NS4, and NS5) and the secretion of IFN-gamma and interleukins (IL-4, IL-5, IL-10, and IL-12) were tested by ELISA. Furthermore, IFN-gamma as well as IL-10 secreting CD4+ T cells were quantitated by intracellular cytokine staining. Anti-HCV core and NS3-specific IgG subclass antibodies were quantitated in the corresponding patient sera. Sustained therapy responders had more frequent and stronger NS3 and helicase-specific cellular immune responses than nonresponders, untreated HCV patients and healthy controls. Independent from therapy outcome HCV-stimulated T cells in IFN-alpha treated patients secreted preferentially IFN-gamma The Th2 cytokines IL-4 and IL-10 were even decreased in nonresponders, while the IL-12 secretion was not influenced. With respect to the humoral immune response sustained complete responders showed significantly reduced IFN-gamma independent anti-HCV-core and -NS3 IgG1 antibody synthesis. In conclusion, vigorous NS3-specific T-helper cell responses were associated with viral clearance in IFN-alpha recipients; however, the cytokine and antibody analysis argues against a Th1/Th2 imbalance as a major factor that influence the therapy outcome.

Hepatitis B and hepatitis C co-infection in patients with HIV

HAART has increased the life expectancy of patients with HIV. However, as their life expectancy increases, it becomes increasingly important to focus on the management of concurrent illnesses such as chronic HBV and HCV infections which have the potential to increase mid to long term morbidity and mortality. Shared epidemiological risks have resulted in the HIV infected population having a higher incidence of both HBV and HCV than those uninfected with HIV. Co-infection with HIV modifies the natural history of HBV infection, increasing the rate of viral replication, risk of carriage and chronic hepatitis but without increasing liver necroinflammatory processes. In chronic HCV infection, the presence of HIV enhances the risk of severe liver disease. There is no evidence as yet that HBV directly impacts on HIV disease progression but HCV infection increases the risk of death or an AIDS defining illness and impairs CD4+ T cell recovery during antiretroviral therapy. Treatment of either hepatitis virus is complex because of pharmacokinetic interactions with components of HAART regimens.

Interleukin-12 p40/p70 ratio and in vivo responsiveness to IFN-alpha treatment in chronic hepatitis C

To evaluate the relationship between cytokine balance and responsiveness to interferon-alpha (IFN-alpha), we investigated the production of IFN-gamma, interleukin-10 (IL-10), IL-12 p70, and IL-12 p40 by peripheral blood mononuclear cell (PBMC) cultures from patients with chronic hepatitis C (CHC) before and after 1 year of IFN-alpha treatment. Before the therapy, responder (R) patients exhibited lower IFN-gamma release, higher IL-10 production, and higher values of the IL12 p40/p70 ratio compared with nonresponders (NR). Increased sensitivity to the effects of IL-12 and IL-10, as well as higher IL-12-dependent IFN-gamma secretion, were also found in the R subset. After IFN-alpha therapy, an increase in IFN-gamma production and a decrease in the IL-12 p40/p70 ratio were observed in R patients, whereas opposite results were obtained in the NR group. Finally, the therapy induced downregulation of IL-10 production and cell responsiveness to recombinant IL-12 in all patients. These findings imply that predominance of a T helper 2 (Th2) cytokine profile in CHC patients favors the beneficial effects of IFN-alpha, thus suggesting a therapeutic role for Th1-driven stimulation of immune response. The findings also stress the primary importance of the IL-12 p40 and p70 balance in the modulation of immune responses to hepatitis C virus (HCV).

Modulation of tumor necrosis factor receptors 1 and 2 in chronic hepatitis B and C: the differences and implications in pathogenesis

Tumor necrosis factor (TNF) plays a role in the pathogenesis of chronic hepatitis B (CHB) and chronic hepatitis C (CHC). The difference in the cytokine responses between hepatitis B virus (HBV) and hepatitis C virus (HCV) infections may have implications in the pathogenesis of these diseases. We performed a comparative study to examine the possible differences in the TNF-TNF receptor (TNFR) response between CHB and CHC. We studied the cytokine levels of 38 patients with CHB, 40 patients with CHC and 9 patients with dual hepatitis B and C, and compared them with the baseline levels of 12 healthy controls. The plasma levels of TNF-alpha, interferon-gamma, interleukin (IL)-2, IL-4, IL-10 and soluble TNFR-1 and 2 (sTNFR-1 and 2) were quantified by enzyme-linked immunosorbent assays. The expression of TNFR-1 and 2 in liver tissues was examined in 30 cases of CHB and 15 cases of CHC by semiquantitative reverse transcription polymerase chain reaction. The results showed that sTNFR-1 levels correlated with liver inflammation in all patients, whereas this correlation was not found with sTNFR-2 or other cytokines. Liver inflammation indicators were higher in HCV RNA+ than in HCV RNA- CHC. Most significantly, sTNFR-1 levels correlated with liver inflammation in CHB, but not in CHC. However, the expression of TNFR-1 and 2 in liver was similar between CHB and CHC. These findings suggest that the TNFR signal transduction pathway is modulated differently in HBV and HCV infection.

Humoral and CD4(+) T helper (Th) cell responses to the hepatitis C virus non-structural 3 (NS3) protein: NS3 primes Th1-like responses more effectively as a DNA-based immunogen than as a recombinant protein

The non-structural 3 (NS3) protein is one of the most conserved proteins of hepatitis C virus, and T helper 1 (Th1)-like responses to NS3 in humans correlate with clearance of infection. Several studies have proposed that DNA-based immunizations are highly immunogenic and prime Th1-like responses, although few head-to-head comparisons with exogenous protein immunizations have been described. A full-length NS3/NS4A gene was cloned in eukaryotic vectors with expression directed to different subcellular compartments. Inbred mice were immunized twice in regenerating tibialis anterior (TA) muscles with either plasmid DNA or recombinant NS3 (rNS3). After two 100 micrograms DNA immunizations, specific antibody titres of up to 12960 were detected at week 5, dominated by IgG2a and IgG2b. NS3-specific CD4(+) T cell responses in DNA-immunized mice peaked at day 13, as measured by proliferation and IL-2 and IFN-gamma production. Mice immunized with 1-10 micrograms rNS3 without adjuvant developed antibody titres comparable to those of the DNA-immunized mice, but dominated instead by IgG1. CD4(+) T cell responses in these mice showed peaks of IL-2 response at day 3 and IL-6 and IFN-gamma responses at day 6. With adjuvant, rNS3 was around 10-fold more immunogenic with respect to speed and magnitude of the immune responses. Thus, immunization with rNS3 in adjuvant is superior to DNA immunization with respect to kinetics and quantity in priming specific antibodies and CD4(+) T cells. However, as a DNA immunogen, NS3 elicits stronger Th1-like immune responses, whereas rNS3 primes a mixed Th1/Th2-like response regardless of the route, dose or adjuvant.

Cytokines and chemokines in the immune response to hepatitis C infection

Over 170 million people are infected with the hepatitis C virus worldwide, resulting in a large disease burden and significant mortality. Hepatitis C virus is rarely cleared in the acute phase of the infection and most patients become chronically infected; a proportion of these patients develop progressive liver disease and fibrosis. The outcome of infection depends on the immune responses of both the innate and cognate immune systems, and these in turn are orchestrated by networks of cytokines and chemokines. There is evidence that a vigorous type 1 immune response to viral proteins is required for viral elimination, and the recruitment of such effector cells to the liver is dependent on the local activity of specific inducible chemokines. Multiple factors determine the ability of the hepatitis C virus to survive host immune responses, including an ability to alter the cytokine profile secreted by T cells and to cause resistance to the effects of antiviral cytokines such as interferon. In the present review, we briefly cover the important advances made in this area over the past 12 months.

Insights into the epidemiology, natural history and pathogenesis of hepatitis C virus infection from studies of infected donors and blood product recipients

Studies of patients with post-transfusion non-A, non-B hepatitis and their implicated donors were critical to the discovery of hepatitis C virus (HCV) and to the development and progressive enhancement of HCV immunoassays for donor screening and diagnostic applications. Post-transfusion HCV cases have also been used to define the time course of viral and immunological markers following acute infection. Even more precise data on the timing and characteristics of viremia and immune responses during primary HCV infection have been derived from studies of serial samples from source plasma donors who were identified while in the process of infection and seroconversion. Such data have been critical to the derivation of estimates for the viremic, pre-seroconversion window period, and hence projections of the yield of addition of nucleic acid amplification technology (NAT) or HCV core antigen enzyme immunoassays (Ag-EIAs) to antibody screening in donor and diagnostic settings. In addition to these implications for screening and diagnosis, studies of HCV in the blood donor and blood product recipient settings have yielded substantial insights into the epidemiology, pathogenesis and prognosis of HCV infection. In the future, prospective studies of blood and plasma donors detected in the primary phase of HCV infection by NAT screening, will be important for defining viral and host genetic and immunological determinants of clearance of acute viremia, as well as for investigating the benefits of early treatment. Thus, the findings from studies of HCV among donors and blood product recipients have yielded and should continue to provide important insights into HCV pathogenesis leading to novel diagnostic, therapeutic and vaccination strategies.

Impaired dendritic cell maturation in patients with chronic, but not resolved, hepatitis C virus infection

Dendritic cells (DCs) are important for the initiation of immune responses to foreign antigens. Their antigen uptake and presentation capacities enable them to prime and activate T cells. Immature DCs capture antigens; however, they must be activated to mature before serving as efficient antigen-presenting cells. The antigen-presenting capacity of DCs can be diminished during viral infection and as a consequence of tumor formation. Chronic infection with hepatitis C virus (HCV) has been shown to affect the allostimulatory function of DCs. In this study, it is demonstrated that monocyte-derived DCs from patients with chronic HCV infection do not respond to maturation stimuli. Instead, they maintain their immature phenotype, reflected by the pattern of cell surface markers and by their continued capacity to uptake antigen. Moreover, their allostimulatory abilities are impaired compared with those of mature DCs derived from healthy donors. To investigate a possible correlation between viral clearance and this DC maturation defect, patients with resolved HCV infection after a course of antiviral therapy were studied. Results demonstrate that DCs from patients who cleared HCV behaved like DCs from healthy donors: in response to maturation stimuli, they decrease antigen uptake, up-regulate expression of appropriate surface markers, and are potent stimulators of allogeneic T cells. (Blood. 2001;97:3171-3176)

Immunopathogenesis of hepatitis C viral infection: Th1/Th2 responses and the role of cytokines

Hepatitis C virus is a common cause of hepatocellular injury that is associated with complex and vigorous immunologic mechanisms. Both humoral and cell-mediated immune responses participate in the host defense against hepatitis C viral infection, but there is increasing recognition of the roles played by the cell-mediated response, and in particular the cytokine system, in the immunopathogenesis of chronic hepatitis C. The cell-mediated response depends on cytotoxic and helper T-cell activity, and functions through the actions of cytokines to regulate macrophages, natural killer cells, and antiviral cellular proteins. Cytokines produced in the liver are essential in defending the host against hepatitis C invasion, but they have also been implicated in the hepatocellular injury seen in the majority of chronically infected patients. Cytokines are thought to be involved in the pathogenesis of hepatitis C under conditions where the virus can mutate effectively and evade T-cell immune defense mechanisms. Persistent infection upsets the balance between immunostimulatory and inhibitory cytokines which can prolong inflammation and lead to necrosis, fibrosis, and chronic liver disease.

ELISPOT analysis of hepatitis C virus protein-specific IFN-gamma-producing peripheral blood lymphocytes in infected humans with and without cirrhosis

An improved ability to monitor hepatitis C virus (HCV)-specific T cell immunity in infected patients may provide novel information regarding the pathogenesis and prognosis of this infection. We used an ELISPOT assay to analyze a cross-section of HCV-infected humans. HCV-infected patients without cirrhosis, those with cirrhosis, and controls with other liver diseases were tested for recall responses to HCV Core and NS3 proteins. Peripheral blood lymphocytes (PBLs) from HCV-infected patients without cirrhosis responded to NS3 and Core proteins, producing predominantly IFN-gamma, with little IL-4 or IL-5. In contrast, PBLs from HCV-infected patients with cirrhosis responded to NS3, but not to the Core protein, suggesting a selectively altered immune state during cirrhosis. Our data provide support for the notion that HCV-specific IFN-gamma-producing immunity is important in the pathogenesis of progressing HCV-related disease.

Issues in HIV/Hepatitis C Co-infection

Co-infection of patients with hepatitis C virus (HCV) and HIV is prevalent. HCV disease is clearly exacerbated in the setting of HIV disease, and the long-term effects of HCV have become an increasing concern as patients live longer on highly active antiretroviral therapy. Although treatment for HCV disease is evolving rapidly, its role in the HIV-infected patient is not well delineated. This review will focus on the major issues in the HIV/HCV co-infected patient and discuss therapy for HCV in the era of highly active antiretroviral therapy.

Lack of evidence for the Th2 predominance in patients with chronic hepatitis C

A T helper (Th)1 to Th2 shift has been proposed to be a critical pathogenic determinant in chronic hepatitis C. Here, we evaluated mitogen-induced and hepatitis C virus (HCV) core antigen-induced cytokine production in 28 patients with biopsy-proven chronic hepatitis C. Flow cytometry demonstrated that after mitogenic stimulation the percentage of Th2 cells (IL-4 + or IL-13 +) and Th0 cells (IFN-gamma/IL-4 + or IL-2/IL-13 +) did not differ between patients and controls. In contrast, the percentage of Th1 cells (IFN-gamma + or IL-2 +) was significantly increased in CD4 +, CD8 +, 'naive'-CD45RA + and 'memory'-CD45RO + T-cell subsets from patients versus controls. Similar results were obtained by ELISA testing supernatants from mitogen-stimulated, unfractionated peripheral blood mononuclear cell (PBMC) cultures. Interferon-alpha treatment was associated with a reduction in the mitogen-induced Th1 cytokine response in those patients who cleared their plasma HCV-RNA. Analysis of cytokine expression by CD4 + T cells after HCV core antigen stimulation in a subgroup of 13 chronic hepatitis C patients demonstrated no cytokine response in 74% of these patients and an IFN-gamma-restricted response in 26%. Finally, no Th2 shift was found in lipopolysaccharide-stimulated monocytes. These data indicate that a Th1 to Th2 shift does not occur in chronic hepatitis C.

Recurrence of hepatitis C after liver transplantation is associated with increased systemic IL-10 levels

BACKGROUND

Recurrence of hepatitis C after liver transplantation is an almost universal occurrence. T-cell derived cytokines have an important role in the development of liver damage associated with chronic hepatitis C, their post-transplant levels, however, have not been correlated with histologic recurrence of the disease.

AIMS

We sought to analyze levels of TNF-alpha, soluble IL-2 receptor, IL-4 and IL-10 at 1 month, 6 months and 1 year after transplantation in 27 patients undergoing transplantation for hepatitis C related end-stage liver disease.

METHODS

HCV RNA levels were monitored by a branched-chain DNA signal amplification assay. Diagnosis of recurrent hepatitis was based on 1-year protocol biopsies and on biopsies performed for liver enzyme elevations.

RESULTS

Recurrent hepatitis C was detected in 52% (n=14) of the 27 patients. HCV RNA levels rose over time in all patients regardless of histologic recurrence. TNF-alpha, and IL-4 levels, although elevated, did not show specific patterns over time or in correlation with recurrence. Similarly, the early elevation followed by a gradual decrease over the first year in the amount of soluble IL-2 receptor was not related to histologic recurrence. We observed a significant increase in circulating IL-10 levels over the first year in patients with biopsy-proven recurrence, while patients with no signs of histologic recurrence displayed increased, but steady levels.

CONCLUSIONS

These results suggest that while these cytokines are associated with post-transplant recurrence of hepatitis C, their production may be altered by additional factors.

Hepatitis C virus core protein inhibits interleukin 12 and nitric oxide production from activated macrophages

A characteristic feature of hepatitis C virus (HCV) infection is a high frequency of persistence and the progression to chronic liver diseases. Recent data suggest that prevalent T helper (Th) 2 immunity as well as weak HCV-specific T-cell response is associated with viral persistence. Here, we showed that the production of interleukin 12 (IL-12) and nitric oxide (NO) that is critical for the induction of Th1 and innate immunity, but not that of tumor necrosis factor alpha (TNF-alpha), was significantly suppressed in both HCV core-expressing macrophage cell lines and mouse peritoneal macrophages treated with recombinant core protein. In addition, IL-12 p40 promoter activity was repressed by the presence of HCV core in macrophages stimulated with lipopolysaccharride (LPS) following IFN-gamma treatment, indicating that IL-12 production may be downregulated at the transcriptional level. We also found that proliferation of T cells and IFN-gamma production in mixed lymphocyte reactions (MLR) with core-expressing cells were inhibited. Taken together, our results suggest that HCV core protein could play roles in suppressing the induction of Th1 immunity through inhibition of IL-12 and NO production.

Transcriptional activation of the interleukin-2 promoter by hepatitis C virus core protein

Most patients infected with hepatitis C virus (HCV) become chronic carriers. Viruses that efficiently establish persistent infections must have effective ways of evading host defenses. In the case of HCV, little is known about how chronic infections are established or maintained. Besides hepatocytes, several reports suggest that HCV can infect T and B lymphocytes. Since T cells are essential for viral clearance, direct or indirect effects of HCV on T-cell function could influence the outcome of infection. Given that T-cell growth and differentiation require the cytokine interleukin 2 (IL-2), we asked whether HCV might modulate synthesis of IL-2. Portions of the HCV polyprotein were expressed in Jurkat cells under a variety of conditions. We found that the highly conserved HCV core protein, in combination with other stimuli, was able to dramatically activate transcription from the IL-2 promoter. The carboxy-terminal hydrophobic portion of the core protein was required for this activity. Activation was dependent on nuclear factor of activated T cells (NFAT), occurred in cells deficient in the tyrosine kinase p56(lck), and could be blocked by addition of cyclosporin A and by depletion of calcium. These results suggest that the HCV core protein can activate transcription of the IL-2 promoter through the NFAT pathway. This novel activity may have consequences for T-cell development and establishment of persistent infections.

Ribavirin enhancement of hepatitis C virus core antigen-specific type 1 T helper cell response correlates with the increased IL-12 level

BACKGROUNDS/AIMS

Combination IFN-a and ribavirin therapy for hepatitis C virus-infected patients has been reported to improve the response rate up to 50%. In this study, we aimed to study further the role of ribavirin in hepatitis C virus-specific immune responses.

METHODS

We immunized mice with hepatitis C virus core protein with or without different concentrations of ribavirin. Forty days after immunization, hepatitis C virus-specific immune responses were followed in these mice.

RESULTS

We found that the mice immunized with core antigen once every 2 weeks and 0.5 mg ribavirin every day showed higher levels of core-specific IgG2 compared with those mice immunized with core antigen only. In addition, core antigen-stimulated spleen cells produced higher levels of T helper type 1 cytokines and the core-specific cytotoxic T cell activity also increased significantly. Furthermore, lipopolysaccharide-stimulated peritoneal cells produced higher levels of IL-12 in ribavirin-treated mice, and peritoneal cells isolated from naive mice also produced significantly higher level of IL-12 when cultured with ribavirin.

CONCLUSIONS

Ribavirin may significantly promote the T helper type 1 immune response in vivo, and, furthermore, the effect of ribavirin on IL-12 level produced by accessory cells may contribute to the T helper type 1 enhancing effect.

Different cytokine profiles of peripheral blood mononuclear cells from patients with persistent and self-limited hepatitis C virus infection

An imbalance between T helper cell Th1 and Th2 like cytokines has been described in several chronic infectious diseases. In an attempt to characterise the mechanism responsible for viral persistence in hepatitis C virus (HCV)-related chronic infection, we analyzed Th1 cytokines (IL-2, IL-12, IFN-gamma) and Th2 cytokines (IL-4, IL-10) production by phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC) derived from ten patients with viremic chronic hepatitis C, five healthy HCV seropositive individuals and four HCV seronegative individuals. Cytokine production was determined by enzyme-linked immunosorbent assay (ELISA) after 72 h of stimulation. The results showed that the production of IFN-gamma by PHA-stimulated PBMC was decreased in patients with hepatitis C infection (P=0.05). IL-4 production was not detected in both patients and controls, while no difference was observed for IL-2, IL-10 and IL-12 production between patients and controls. Furthermore, IL-12 and IFN-gamma production was weaker in patients with viremic chronic hepatitis C than in subjects who were able to clear the virus (P=0.01; P=0.03, respectively). These results clearly indicate that a defect both in IL-12 and IFN-gamma production may contribute to the persistence of HCV infection.

Prednisolone priming enhances Th1 response and efficacy of subsequent lamivudine therapy in patients with chronic hepatitis B

Asian lamivudine trial has shown that hepatitis B e antigen (HBeAg) seroconversion rate during 1 year of lamivudine therapy was only 16% but was 64% in the subgroup of patients with a pretherapy serum alanine transaminase (ALT) level over 5 times the upper limit of normal (ULN). To test whether ALT rebound following corticosteroid priming enhances response to lamivudine therapy, a pilot study was conducted in 30 patients with ALT levels less than 5x ULN (43-169; N < 36 U/L). They received 30 mg of prednisolone daily for 3 weeks, 15 mg daily for 1 week, no treatment for 2 weeks, and then 150 mg of lamivudine daily for 9 months. Complete response (CR) was defined as ALT normalization with HBV-DNA seroclearance and HBeAg seroconversion. Peripheral blood mononuclear cell proliferation and cytokine secretion in response to recombinant HBV core antigen were serially assayed in 7 patients during priming and after withdrawal of prednisolone. Clinical rebound with an ALT over 5x ULN was observed in 20 patients (67%). Of these 20, 12 (60%) showed CR as compared with 1 (10%) of the 10 patients without significant ALT rebound (P <.002). The HBeAg seroconversion sustained in 70% of the patients 3 to 6 months after the end of lamivudine therapy. Immunological assays revealed that the responders showed Th1 dominant response and higher stimulation index to prednisolone priming. No serious side effect was encountered. These results suggest that corticosteroid priming induced immune/ALT rebound greatly enhances response to lamivudine therapy in chronic hepatitis B. Confirmation by randomized controlled trial is needed.

Type 2 cytokines predominate in the human CD4(+) T-lymphocyte response to Epstein-Barr virus nuclear antigen 1

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus that persistently infects 85% of the adult population worldwide. In this report, we examine the proliferative response and cytokine secretion profile of CD4(+) T lymphocytes from a panel of unrelated EBV-positive donors against two EBV latent antigens, EBNA1 and EBNA3C. Substantial proliferative responses by CD4(+) lymphocytes were demonstrated to both antigens in multiple, randomly selected donors. Surprisingly, we observed a striking and consistent difference in cytokine response to EBNA1 and EBNA3C. EBNA1-specific CD4(+) T lymphocytes from multiple unrelated donors preferentially produced type 2-like cytokines in response to antigenic stimulation, while the response to EBNA3C was a characteristic type 1 response. The implications of these findings for EBV persistence and the development of EBV-associated malignancies are discussed.

Vigorous peripheral blood cytotoxic T cell response during the acute phase of hepatitis C virus infection

After infection by hepatitis C virus (HCV), a minority of patients develop acute symptomatic disease and some of them are able to clear the virus. In this study, we analyzed peripheral blood mononuclear cells from nine patients with acute symptomatic disease with respect to their cytotoxic T lymphocyte (CTL) response using a panel of HCV-derived peptides in a semiquantitative secondary in vitro culture system. We could detect early CTL responses in 67% of these patients. The CTL responses were directed against multiple viral epitopes, in particular within the structural (core 2-9, core 35-44, core 131-140, and core 178-187) and nonstructural regions of the virus (NS3 1073-1081, NS3 1406-1415, NS4 1807-1816, NS5 2252-2260, and NS5B 2794-2802). We compared the CTL responses displayed by recently and chronically infected HLA-A2-positive patients. Virus-specific CTLs were detectable in chronic carriers but the percentage of positive peptide-specific CTL responses was significantly higher in recently infected patients (P = 0.002). Follow-up of recently infected patients during subsequent disease development showed a significant decrease in the values and proportions of positive peptide-specific CTL responses (P = 0.002 and 0.013, respectively). Patients with limited viral replication exhibited significantly more vigorous early responses (P = 0.024). These data suggest a protective role for the early antiviral CTL response in HCV infection.

Indispensable role for TNF-alpha and IFN-gamma at the effector phase of liver injury mediated by Th1 cells specific to hepatitis B virus surface antigen

We report the development and characterization of a novel model of severe hepatitis induced against hepatitis B virus surface Ag (HBsAg). HBsAg was successfully targeted into the liver in soluble form. Using this unique property of HBsAg, we established a liver injury model induced by HBsAg-specific Th1 cells. Severe liver injury was induced in C57BL/6 mice by injection of HBsAg together with HBsAg-specific Th1 cells. Histochemical examination demonstrated extensive necroinflammatory hepatic lesions in these animals. Application of this liver injury model to mutant or gene knockout mice enabled us to define the effector mechanisms of Th1 cells in fulminant hepatitis. When Fas-deficient lpr mice were used as recipients, a similar degree of liver injury was induced as in wild-type mice. Moreover, HBsAg-specific Th1 cells obtained from perforin-/- mice could induce severe liver injury in both wild-type and lpr mice. These results indicated that neither Fas ligand nor perforin are essential for Th1-mediated liver injury in this model. Pretreatment with anti-TNF-alpha mAb prevented liver injury, whereas severe liver injury was induced in TNF-alpha-/- mice. Moreover, IFN-gamma receptor-deficient mice were resistant to Th1-mediated liver injury. Therefore, TNF-alpha and IFN-gamma, which were produced by HBsAg-specific Th1 cells during the effector phase, appeared to be indispensable in the pathogenesis of fulminant hepatitis.

Pre-treatment with prednisolone does not improve the efficacy of subsequent alpha interferon therapy in chronic hepatitis C

BACKGROUND/AIMS

Alpha interferon administration is quite disappointing as a single therapy in chronic hepatitis C. A brief course of corticosteroid therapy might increase the effectiveness of subsequent alpha interferon administration, but data on this issue are controversial.

METHODS

One hundred and fifty-six consecutive patients with chronic hepatitis C were randomly assigned to be treated blind with tapering doses of oral prednisolone or placebo for 4 weeks. Two weeks after cessation of therapy, patients received alpha interferon (3 MU t.i.w.) for 48 weeks and were followed for 24 additional weeks. Response was defined by the presence of normal alanine aminotransferase (ALT) and negative HCV-RNA in serum.

RESULTS

ALT activity decreased during prednisolone administration and rebounded upon withdrawal in 38% of the patients treated with this drug. Significant changes in serum bilirubin were not observed. HCV-RNA serum concentration tended to increase during prednisolone administration and to decrease upon withdrawal. ALT and HCV-RNA did not change during administration of placebo. At the end of interferon administration, 33% of patients treated with prednisolone and 25% of those treated with placebo presented biochemical and virological response. At the end of post-treatment follow-up, response was maintained in 12% and 13% of patients treated with prednisolone or placebo respectively. Response was not related to ALT or HCV-RNA changes observed during the pre-interferon phase of the study. No adverse events related to prednisolone administration were observed.

CONCLUSIONS

Prednisolone administration and withdrawal induced a rebound in ALT activity and a decrease in HCV-RNA serum concentration in about one third of the patients with chronic hepatitis C. However, these changes did not enhance the effectiveness of subsequent alpha interferon therapy.

DNA-Based immunization produces Th1 immune responses to hepatitis delta virus in a mouse model

Hepatitis delta virus (HDV) superinfection is one of the major causes of fulminant hepatitis in endemic areas of hepatitis B virus (HBV) infection. Currently, there is no effective treatment or vaccine against HDV superinfection. DNA-based immunization is a promising antiviral strategy to prevent or treat persistent viral infections. In this study, we investigated the immunological effects of DNA vaccines against HDV in BALB/c mice. Plasmid (pD) encoding large hepatitis D antigen (L-HDAg), or plasmid (pS/pD) coexpressing hepatitis B surface antigen (HBsAg) and L-HDAg, were injected into mice intramuscularly. The seroconversion rate, anti-HBs levels, anti-HDV titers, T-cell proliferation responses, and T-helper (Th)-release cytokine profiles were analyzed. Mice immunized with plasmids, pS/pD or pD, produced low, but significant, titers of anti-HDV antibodies. In contrast, pS/pD induced much stronger anti-HBs titers in the immunized animals. Interestingly, splenic lymphocytes derived from pS/pD-inoculated mice demonstrated significant proliferation responses to recombinant HBsAg and HDAg, and resulted in a Th1-like immune response as suggested by the production of interferon gamma (INF-gamma) and interleukin-2 (IL-2), but not IL-4. The splenic lymphocyte derived from the pD-inoculated mice showed a similar Th1 response to the stimulation of HDAg, but not to HBsAg. In conclusion, our results suggest that DNA vaccines against HDV can induce significant cellular immune responses with a Th1 preference. HBV and HDV coimmunization can be performed by DNA vaccines. These results are promising for the future development of prophylactic and therapeutic HDV vaccines.

Soluble CD30 serum level in HCV-positive chronic active hepatitis: A surrogate marker of disease activity?

In the present study, high levels of CD30s, a glycoprotein preferentially expressed and released by T lymphocytes producing Th(2)-type cytokines, were seen in the sera of patients with chronic hepatitis C, and a correlation with histological activity of the disease was found. CD30s levels were assayed in the sera of 29 HCV RNA-positive patients with histologically proven chronic active hepatitis and in 30 healthy blood donors. Thirteen of 29 (45%) HCV patients had CD30s serum levels above the normal range (>20 U/ml). Mean CD30s serum levels were significantly higher in HCV patients than in controls (P<0.0005). A positive correlation was found between serum CD30s levels and both the histological activity index (r=0.59, P=0.001) and ALT serum levels (r=0.5; P=0.006). The raised CD30s level found in more severe HCV liver disease indirectly suggests activation and expansion of Th(2)cells. CD30s levels could represent a useful surrogate marker of activity in chronic HCV infections.

The ribavirin analog ICN 17261 demonstrates reduced toxicity and antiviral effects with retention of both immunomodulatory activity and reduction of hepatitis-induced serum alanine aminotransferase levels

The demonstrated utility of the nucleoside analog ribavirin in the treatment of certain viral diseases can be ascribed to its multiple distinct properties. These properties may vary in relative importance in differing viral disease conditions and include the direct inhibition of viral replication, the promotion of T-cell-mediated immune responses via an enhanced type 1 cytokine response, and a reduction of circulating alanine aminotransferase (ALT) levels associated with hepatic injury. Ribavirin also has certain known toxicities, including the induction of anemia upon chronic administration. To determine if all these properties are linked, we compared the D-nucleoside ribavirin to its L-enantiomer (ICN 17261) with regard to these properties. Strong similarities were seen for these two compounds with respect to induction of type 1 cytokine bias in vitro, enhancement of type 1 cytokine responses in vivo, and the reduction of serum ALT levels in a murine hepatitis model. In contrast, ICN 17261 had no in vitro antiviral activity against a panel of RNA and DNA viruses, while ribavirin exhibited its characteristic activity profile. Importantly, the preliminary in vivo toxicology profile of ICN 17261 is significantly more favorable than that of ribavirin. Administration of 180 mg of ICN 17261 per kg of body weight to rats by oral gavage for 4 weeks generated substantial serum levels of drug but no observable clinical pathology, whereas equivalent doses of ribavirin induced a significant anemia and leukopenia. Thus, structural modification of ribavirin can dissociate its immunomodulatory properties from its antiviral and toxicologic properties, resulting in a compound (ICN 17261) with interesting therapeutic potential.

Activation of nuclear factor kappaB in hepatitis C virus infection: implications for pathogenesis and hepatocarcinogenesis

The hepatitis C virus (HCV) core protein is a multifunctional protein. It may bind to the death domain of tumor necrosis factor receptor 1 (TNFR1) and to the cytoplasmic tail of lymphotoxin-beta receptor, implying that it may be involved in the apoptosis and anti-apoptosis signaling pathways. In vitro studies have been inconclusive regarding its ability to inhibit or enhance TNF-alpha-induced apoptosis. To address this issue, electrophoretic mobility shift assay (EMSA) and immunohistochemical studies were used to show the activation of nuclear factor kappaB (NF-kappaB) in HCV-infected liver tissues and in HCV core-transfected cells. The activation of NF-kappaB was correlated with the apoptosis assays. The results showed that NF-kappaB activation could be shown in HCV-infected livers and HCV core-transfected cells. The data of EMSA correlated with those of immunohistochemical studies, which revealed a higher frequency of NF-kappaB nuclear staining in HCV-infected than in normal livers. NF-kappaB activation conferred resistance to TNF-alpha-induced apoptosis in HCV core-transfected cells. Inhibition of NF-kappaB activation by pyrrolidine dithiocarbamate sensitized them to TNF-alpha-induced apoptosis. These findings suggest that HCV infection may cause anti-apoptosis by activation of NF-kappaB and implicate a mechanism by which HCV may evade the host's immune surveillance leading to viral persistence and possibly to hepatocarcinogenesis.

Hepatitis C virus-specific T-cell reactivity during interferon and ribavirin treatment in chronic hepatitis C

BACKGROUND & AIMS

The role of virus-specific T-helper lymphocyte reactivity in determining the therapeutic response in chronic hepatitis C virus (HCV) infection is not fully understood.

METHODS

We studied CD4(+) T lymphocyte proliferation together with interferon (IFN)-gamma and interleukin (IL)-10 production from peripheral blood mononuclear cells in response to 4 HCV antigens (core, NS3, NS4, and NS5) in 25 patients with chronic hepatitis C undergoing antiviral therapy with IFN alone or in combination with ribavirin, prospectively, before, during, and after treatment.

RESULTS

HCV-specific T-cell reactivity was uncommon at baseline but increased markedly during antiviral therapy, peaking around treatment weeks 4-8. Resolution of hepatitis C viremia was significantly more likely in patients who developed HCV-specific T-cell proliferation with increased IFN-gamma production. The main difference in T-cell reactivity of patients treated with IFN plus ribavirin was a significantly lower production of IL-10, whereas lymphocyte proliferation was similar to that in patients receiving IFN monotherapy.

CONCLUSIONS

Treatment-induced control of hepatitis C viremia is associated with the development of HCV-specific T-cell responses with enhanced IFN-gamma and low IL-10 production. The greater efficacy of combination therapy with IFN-alpha plus ribavirin may be related to its ability to suppress HCV-specific IL-10 production.

Relationship between interferon-gamma, interleukin-10, and interleukin-12 production in chronic hepatitis C and in vitro effects of interferon-alpha

In the current study, increased interferon (IFN)-gamma, interleukin (IL)-10, and IL-12 p40 serum levels were observed in patients with chronic hepatitis C (CHC) compared to controls. Patients also displayed an increased spontaneous IFN-gamma release but a deficient peripheral blood mononuclear cells (PBMC) IFN-gamma production following stimulation with Staphylococcus aureus Cowan I strain (SAC). No difference was found with reference to spontaneous or phytohaemagglutinin (PHA)-induced IL-10 release between patients and controls, whereas a higher IL-12 p70 and IL-12 p40 secretion triggered by SAC was observed in patients. Moreover, IL-12 p40/p70 ratio following SAC stimulation was higher in patients compared to controls and a negative correlation was found between this ratio and IFN-gamma amounts. Recombinant IL-12 (rIL-12) as well as neutralizing anti-IL-10 monoclonal antibodies (mAbs) were able to restore the compromised IFN-gamma production. Of note, anti-IL-10 supplementation induced a lower IL-12 p40/p70 ratio in HCV subjects as compared to controls. Finally, IFN-alpha upregulated in vitro IFN-gamma, IL-10, and IL-12 p70 release but not IL-12 p40 secretion, this giving rise to a normalization of IL-12 p40/p70 ratio. The data suggest the occurrence of an enhanced responsiveness to IL-10 modulating effects, likely mediated by an imbalance of IL-12 p40/p70 ratio, in chronic HCV infection. Cytokine balance restoration might thus contribute to achieve therapeutical results in chronic hepatitis C.

The relationship between angiogenesis and the immune response in carcinogenesis and the progression of malignant disease

Recent studies have demonstrated that angiogenesis and suppressed cell-mediated immunity (CMI) play a central role in the pathogenesis of malignant disease facilitating tumour growth, invasion and metastasis. In the majority of tumours, the malignant process is preceded by a pathological condition or exposure to an irritant which itself is associated with the induction of angiogenesis and/or suppressed CMI. These include: cigarette smoking, chronic bronchitis and lung cancer; chronic oesophagitis and oesophageal cancer; chronic viral infections such as human papilloma virus and ano-genital cancers, chronic hepatitis B and C and hepatocellular carcinoma, and Epstein-Barr virus (EBV) and lymphomas; chronic inflammatory conditions such as Crohn's disease and ulcerative colitis and colorectal cancer; asbestos exposure and mesothelioma and excessive sunlight exposure/sunburn and malignant melanoma. Chronic exposure to growth factors (insulin-like growth factor-I in acromegaly), mutations in tumour suppressor genes (TP53 in Li Fraumeni syndrome) and long-term exposure to immunosuppressive agents (cyclosporin A) may also give rise to similar environments and are associated with the development of a range of solid tumours. The increased blood supply would facilitate the development and proliferation of an abnormal clone or clones of cells arising as the result of: (a) an inherited genetic abnormality; and/or (b) acquired somatic mutations, the latter due to local production and/or enhanced delivery of carcinogens and mutagenic growth factors. With progressive detrimental mutations and growth-induced tumour hypoxia, the transformed cell, to a lesser or greater extent, may amplify the angiogenic process and CMI suppression, thereby facilitating further tumour growth and metastasis. There is accumulating evidence that long-term treatment with cyclo-oxygenase inhibitors (aspirin and indomethacin), cytokines such as interferon-alpha, anti-oestrogens (tamoxifen and raloxifene) and captopril significantly reduces the incidence of solid tumours such as breast and colorectal cancer. These agents are anti-angiogenic and, in the case of aspirin, indomethacin and interferon-alpha have proven immunomodulatory effects. Collectively these observations indicate that angiogenesis and suppressed CMI play a central role in the development and progression of malignant disease.

Chemokine and Chemokine Receptor Interactions Provide a Mechanism for Selective T Cell Recruitment to Specific Liver Compartments Within Hepatitis C-Infected Liver

The role played by chemokines in regulating the selective recruitment of lymphocytes to different tissue compartments in disease is poorly characterized. In hepatitis C infection, inflammation confined to portal areas is associated with a less aggressive course, whereas T cell infiltration of the liver parenchyma is associated with progressive liver injury and cirrhosis. We propose a mechanism to explain how lymphocytes are recruited to hepatic lobules during bursts of necroinflammatory activity in chronic hepatitis C infection. We report here that lymphocytes infiltrating hepatitis C-infected liver express high levels of the chemokine receptors CCR5 and CXCR3. However, whereas the CCR5 ligands macrophage inflammatory protein-1α and -1β were largely confined to vessels within portal tracts, the CXCR3 ligands IFN-inducible protein-10 and monokine-induced by IFN-γ were selectively up-regulated on sinusoidal endothelium. In vitro, human hepatic sinusoidal endothelial cells secreted IFN-inducible protein-10 and monokine-induced by IFN-γ in response to stimulation with IFN-γ in combination with either IL-1 or TNF-α. This suggests that intrahepatic Th1 cytokines drive the increased expression of IFN-inducible protein-10 and monokine-induced by IFN-γ and thereby promote the continuing recruitment of CXCR3-expressing T cells into the hepatic lobule in chronic hepatitis C infection.

Decreased frequency of HCV core-specific peripheral blood mononuclear cells with type 1 cytokine secretion in chronic hepatitis C

BACKGROUND/AIM

Since the outcome of hepatitis C infection appears to be correlated with the immune response to the HCV core protein, the aim of this study was to investigate the T cell response to hepatitis C virus core and core-derived antigens.

METHODS

As this response may be regulated importantly by differential secretion of cytokines, we determined the number of peripheral blood mononuclear cells (PBMC) that secreted IL-2, IL-4, IL-10, and IFN-gamma in response to a recombinant HCV core protein and a panel of 19 core-derived peptides, using the ELI-Spot-technique. Two groups of patients were studied: group A: 11 patients with previously self-limited HCV infection; group B: 12 patients with chronic hepatitis C.

RESULTS

In group B significantly less IFN-gamma spot forming cells (SFC) could be detected, both after stimulation with the core protein (0.083+/-0.083 SFC vs. 1.3+/-0.4 SFC/10(5) PBMC; p = 0.005 and with the core-derived peptides (1.3+/-0.5 vs. 4.4+/-1.1 SFC SFC/10(5) PBMC; p = 0.007). By analyzing the cytokine response to each single peptide, we found IFN-gamma responses to peptides aa 39-63 and aa 148-172 in group A but not in group B (p<0.03). In group B also, fewer IL-2 secreting cells were found after peptide stimulation (p = 0.04). Whereas subjects of group B showed IL-10-specific responses to HCV peptides more frequently than patients with self-limiting hepatitis C (p = 0.03), the number of IL-4-producing cells was not different between the two groups.

CONCLUSIONS

The data suggest that patients with persistent viremia and chronic liver disease (group B) have less PBMC showing type 1 cytokine (IL-2, IFN-gamma) responses to HCV core protein than patients with self-limited HCV infection (group A).

Prognostic value of the soluble interleukin-2 receptor in chronic hepatitis C treated with interferon-alfa. Multicenter GER-CYT 04 Group

BACKGROUND/AIMS

High serum levels of the soluble interleukin 2 receptor (sIL-2R) have been reported in patients with chronic hepatitis C. The aims of this study were to determine the evolution of sIL-2R considered as an indicator of activation of T cells in patients with hepatitis C virus (HCV) treated with IFN-alpha and to correlate sIL-2R serum levels with parameters reflecting ongoing liver disease and with outcome of interferon treatment.

METHODS

In a case-control study, we studied patients enrolled in a multicenter randomized clinical trial which had demonstrated the benefit of a reinforced regimen of interferon alpha. Each of the 26 sustained virological responders (SVR) was paired for treatment regimen with two non-responders (NR).

RESULTS

Prior to treatment, higher levels of sIL-2R were found in the sera of 78 patients compared with healthy controls (3791+/-210 pg/ml versus 956+/-88 pg/ml (p<0.001)). In the 78 patients after 4 weeks of treatment, the levels of sIL-2R were higher than pretreatment levels (4308+/-206 pg/ml (p<0.01)). In the NR, levels of sIL-2R increased significantly after 4 weeks of treatment compared with pretreatment levels (p<0.01), and levels of sIL-2R at week 72 were not significantly different from those at pretreatment. Conversely, in the SVR, levels of sIL-2R at week 4 did not significantly increase compared to pretreatment values, and thereafter gradually decreased. At week 72, levels of sIL-2R were significantly lower than before treatment (p<0.001). The difference between levels of sIL-2R at week 4 and before initiation of treatment (delta s IL-2R) was smaller in the SVR than in the NR (142+/-219 pg/ml versus 704+/-107 pg/ml (p<0.02). The disappearance of HCV RNA from the serum at week 4 showed a sensitivity of 92% (95% confidence interval 86-98) and a specificity of 60% (95% confidence interval 49-71), delta sIL-2R had a sensitivity of 42% (95% confidence interval 31-53) and a specificity of 81% (95% confidence interval 79-90) for the prediction of a sustained virological response 6 months after stopping treatment. The disappearance of HCV RNA from serum at week 4 and delta sIL-2R were independent and early predictive factors for a sustained virological response 6 months after stopping treatment.

CONCLUSIONS

At week 4, delta sIL-2R may be a more specific parameter than the disappearance of HCV RNA for assessing total, and hence more sustained, elimination of HCV infection 6 months after stopping treatment.

Recurrence of hepatitis C virus after loss of virus-specific CD4(+) T-cell response in acute hepatitis C

BACKGROUND & AIMS

The prospective comparison of patients with acute hepatitis C virus (HCV) who spontaneously clear the virus with those who cannot achieve viral elimination and progress to chronic hepatitis offers the unique opportunity to analyze natural mechanisms of viral elimination.

METHODS

We studied the HCV-specific CD4(+) T-cell response in 38 patients with acute HCV and correlated the clinical course with the antiviral immune response. The individual HCV-specific T-cell response was assessed in a proliferation assay ((3)H-thymidine uptake) and an enzyme-linked immunospot assay.

RESULTS

Patients were classified according to their clinical course and pattern of CD4(+) T-cell responses in 3 categories: first, patients mounting a strong and sustained antiviral CD4(+)/Th1(+) T-cell response who cleared the virus (HCV RNA-negative; n = 20); second, patients who were unable to mount an HCV-specific CD4(+) T-cell response and developed chronic disease (n = 12); and third, patients who initially displayed a strong CD4(+) T-cell response and eliminated the virus (HCV PCR-negative) but subsequently lost this specific T-cell response (n = 6). The loss of the HCV-specific CD4(+) T-cell response was promptly followed by HCV recurrence.

CONCLUSIONS

The results indicate that a virus-specific CD4(+)/Th1(+) T-cell response that eliminates the virus during the acute phase of disease has to be maintained permanently to achieve long-term control of the virus. The induction and/or maintenance of virus-specific CD4(+) T cells could represent a promising therapeutic approach in HCV infection.