Margaret James Koziel

Influence of Human Immunodeficiency Virus Infection on the Course of Hepatitis C Virus Infection: A Meta-Analysis

Studies have shown that rates of liver disease are higher in persons who are coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) than they are in persons with HCV alone, but estimates of risk vary widely and are based on data for dissimilar patient populations. We performed a meta-analysis to quantify the effect of HIV coinfection on progressive liver disease in persons with HCV. Eight studies were identified that included outcomes of histological cirrhosis or decompensated liver disease. These studies yielded a combined adjusted relative risk (RR) of 2.92 (95% confidence interval [CI], 1.70-5.01). Of note, studies that examined decompensated liver disease had a combined RR of 6.14 (95% CI, 2.86-13.20), whereas studies that examined histological cirrhosis had a pooled RR of 2.07 (95% CI, 1.40-3.07). There is a significantly elevated RR of severe liver disease in persons who are coinfected with HIV and HCV. This has important implications for timely diagnosis and consideration of treatment in coinfected persons.

HLA class I-restricted cytotoxic T lymphocytes specific for hepatitis C virus. Identification of multiple epitopes and characterization of patterns of cytokine release.

Cytotoxic T lymphocytes (CTL) are important to the control of viral replication and their presence may be important to disease outcome. An understanding of the spectrum of proteins recognized by hepatitis C virus (HCV)-specific CTL and the functional properties of these cells is an important step in understanding the disease process and the mechanisms of persistent infection, which occurs in the majority of HCV-infected individuals. In this report we identify HCV-specific CTL responses restricted by the HLA class I molecules A2, A3, A11, A23, B7, B8, and B53. The epitopes recognized by these intrahepatic CTL conform to published motifs for binding to HLA class I molecules, although in some cases we have identified CTL epitopes for which no published motif exists. The use of vectors expressing two different strains of HCV, HCV-1 and HCV-H, revealed both strain-specific and cross-reactive CTL. These HCV-specific CTL were shown to produce cytokines including IFN-gamma, TNF-alpha, GM-CSF, IL-8, and IL-10 in an antigen- and HLA class I-specific manner. These studies indicate that the CTL response to HCV is broadly directed and that as many as five different epitopes may be targeted in a single individual. The identification of minimal epitopes may facilitate peptide-specific immunization strategies. In addition, the release of proinflammatory cytokines by these cells may contribute to the pathogenesis of HCV-induced liver damage.

Pegylated interferon α therapy in acute hepatitis C: Relation to hepatitis C virus–specific T cell response kinetics

Pegylated interferon α (PEG IFN‐α) improves sustained virological response rates in chronic hepatitis C, but neither its role in acute hepatitis C nor the biologic basis for its action has been defined. This prospective study assessed the efficacy of PEG IFN‐α treatment in acute hepatitis C in relation to the kinetics of hepatitis C virus (HCV)‐specific CD4+ T cell responses during therapy and follow‐up. Forty subjects with proven acute hepatitis C who received either PEG IFN‐α plus ribavirin (n = 20) or PEG IFN‐α monotherapy (n = 20) for 24 weeks in addition to 14 untreated subjects with acute hepatitis C were prospectively followed. Serum HCV RNA, HCV‐specific CD4+ T cell responses, and cytokine production were measured before and during therapy and at follow‐up and correlated to the outcome. The sustained virological response rate was 85% with PEG IFN‐α/ribavirin combination and 80% with PEG IFN‐α monotherapy. Five untreated subjects had spontaneous recovery. The frequency, magnitude, and breadth of HCV‐specific CD4+ T helper 1 responses were significantly higher in treated subjects compared with untreated subjects with self‐limited disease or subjects with chronic evolution. The CD4+ T cell responses were maintained in subjects with sustained virological responses and self‐limited disease but fluctuated in those who developed chronic infection. In conclusion, PEG IFN‐α therapy in acute hepatitis induces high rates of sustained virological response and prevents choronicity, probably through efficient early stimulation of multispecific HCV‐specific CD4+ T helper 1 responses. (HEPATOLOGY 2004;39:1721–1731.)

Association of multispecific CD4+ response to hepatitis C and severity of recurrence after liver transplantation*

BACKGROUND & AIMS After liver transplantation for hepatitis C virus (HCV), reinfection of the allograft invariably occurs. Indirect evidence suggests that the cellular immune response may play a central role. The purpose of this analysis was to determine the correlation between HCV-specific peripheral CD4(+) T-cell responses and the severity of recurrence after liver transplantation. METHODS Fifty-eight HCV-seropositive patients, including 43 liver transplant recipients with at least 1 year of histological follow-up, were studied. Peripheral blood mononuclear cells (PBMCs) were isolated from fresh heparinized blood and stimulated with either recombinant HCV antigens (core, E2, NS3, NS4, and NS5) or control antigens. RESULTS Fourteen (40%) of 35 patients with mild or no evidence of histological recurrence within their allografts responded to at least 1 of the HCV antigens. Eleven responded to NS3, 5 to all the nonstructural antigens, and 3 to the HCV core polypeptide alone. In contrast, in the 8 patients with severe HCV recurrence, no proliferation in response to any of the HCV antigens was seen (P = 0. 03) despite responses to the control antigens. CONCLUSIONS Despite immunosuppression, HCV-specific, major histocompatibility complex class II- restricted CD4(+) T-cell responses are detectable in patients with minimal histological recurrence after liver transplantation. In contrast, PBMCs from patients with severe HCV recurrence, despite being able to proliferate in response to non-HCV antigens, fail to respond to the HCV antigens. These findings suggest that the inability to generate virus-specific T-cell responses plays a contributory role in the pathogenesis of HCV-related graft injury after liver transplantation. It is hoped that further characterization of the immunoregulatory mechanisms related to recurrent HCV will provide the rationale for novel therapeutic strategies and diminish the incidence of inevitable graft loss.

Hepatitis C Virus-Specific Cytolytic T Lymphocyte and T Helper Cell Responses in Seronegative Persons

Hepatitis C virus (HCV) is a common infection worldwide, and in most persons, it leads to persistent viremia and liver damage. Efforts to identify the correlates of protective immunity are hampered by this high rate of persistent infection in both infected humans and the only animal model, the chimpanzee. Peripheral blood mononuclear cells from seronegative persons were stimulated with synthetic peptides that represent epitopes recognized by HCV-specific cytotoxic T lymphocytes (CTL) after natural infection. In addition, CD4+ proliferative responses to recombinant HCV proteins were examined in these same persons. CTL responses directed against a peptide epitope of HCV and proliferative responses in 2 HCV-seronegative persons with possible occupational exposure to HCV were found. These otherwise healthy persons were not viremic, suggesting that they may have recovered from acute HCV infection. Characterization of virus-specific immune responses in exposed but seronegative persons may provide important clues as to the nature of protective immunity in HCV.

Hepatic CD1d Expression in Hepatitis C Virus Infection and Recognition by Resident Proinflammatory CD1d-Reactive T Cells

A subset of CD161+CD56+/− NKT cells can recognize glycolipids presented by CD1d and positively or negatively regulate inflammatory responses, including those implicated in several models of hepatitis. CD1d is expressed at very low levels in the healthy liver, but there is a large fraction of CD161+CD56+ NKT cells. There are high levels of nonclassical proinflammatory hepatic CD1d-reactive T cells in hepatitis C virus (HCV) infection. Hepatic inflammatory cells and biliary cells adjacent to portal tract fibrotic areas of HCV-infected donors specifically up-regulated CD1d. A hepatocyte cell line expressing minimal CD1d was efficiently recognized by hepatic CD1d-reactive T cells, suggesting a role for these cells in disease. Hepatic CD1d-reactive T cells from HCV-positive as well as negative donors produced large amounts of IFN-γ with some IL-13, but only rarely detectable IL-4. We confirmed large numbers of hepatic CD161+ T cells, lower levels of CD56+ T cells, and small numbers of classic invariant NKT cells. However, hepatic CD1d-reactivity was not restricted to any of these populations. We suggest virally infected hepatic cells can process potent CD1d-presented liver Ag(s), for surveillance by resident Th1 hepatic CD1d-reactive T cells. This process may be beneficial in acute viral clearance, but in chronic infection could contribute to liver injury.

To be or not to be NKT: Natural killer T cells in the liver

Much of the hepatology literature to date has focused on the adaptive, antigen‐specific response mediated by classical T‐cell populations in both the protection and pathogenesis of liver disease. However, the liver is selectively enriched for cells representative of innate immunity, including natural killer T (NKT) cells. In particular, certain CD1d‐reactive T cells are present at much higher frequencies in the liver than in the peripheral blood. Although these cells have previously been defined mostly on the basis of phenotypic markers, recent emerging literature regarding NKT cell populations has revealed considerable functional complexity. This review summarizes the recent literature regarding NKT cells, which may have important roles in a variety of liver diseases. Although there is an abundance of literature on the phenotype, distribution, and function of these cells in mice, much less is known about them in human health or liver diseases. (HEPATOLOGY 2004;40:1033–1040.)

Cutting edge: Compartmentalization of Th1-like noninvariant CD1d-reactive T cells in hepatitis C virus-infected liver.

Murine intrahepatic lymphocytes (IHL) are dominated by invariant TCR α-chain expressing CD1d-reactive NKT cells, which can cause model hepatitis. Invariant NKT (CD56+/−CD161+) and recently identified noninvariant CD1d-reactive T cells rapidly produce large amounts of IL-4 and/or IFN-γ and can regulate Th1/Th2 responses. Human liver contains large numbers of CD56+ NKT cells but few invariant NKT. Compared with matched peripheral blood T cell lines, primary IHL lines from patients with chronic hepatitis C had high levels of CD161 and CD1d reactivity, but the invariant TCR was rare. CD1d-reactive IHL were strikingly Th1 biased. IHL also demonstrated CD1d-specific cytotoxic activity. Hepatocytes and other liver cells express CD1d. These results identify a novel population of human T cells that could contribute to destructive as well as protective immune responses in the liver. CD1d-reactive T cells may have distinct roles in different tissues.

Progression of fibrosis in hepatitis C with and without schistosomiasis: correlation with serum markers of fibrosis.

Serial liver biopsies are the gold standard by which the progression of fibrosis is evaluated. This longitudinal cohort study assessed the different rates in the progression of fibrosis using serial liver biopsies and serum fibrosis markers YKL‐40 and PIIINP and the cytokines, transforming growth factor beta (TGF‐β) and tumor necrosis factor alpha (TNF−α). A 10‐year cohort study was performed in patients with hepatitis C virus (HCV) alone or HCV and schistosomiasis. Patients were enrolled at the time of acute HCV infection and prospectively evaluated with two liver biopsies (at entry and end of follow‐up), and true rates in the progression of fibrosis were calculated per year. Serum YKL‐40, N‐terminal propeptide of collagen III (PIIINP), TGF‐β, and TNF‐α were measured, as well as the expression of TGF‐β, TNF‐α, and YKL‐40 mRNA in liver tissue. A significant increase in the progression rates of fibrosis occurred in the coinfected group (0.61 ± 0.13) compared with the HCV monoinfection group (0.1 ± 0.06; P < .001)). The progression of fibrosis rate/year had a direct linear correlation for YKL‐40 (r = 0.892, P < .001) and for PIIINP (r = 0.577, P < .01). YKL‐40 showed a linear correlation with TGF‐β (r = 0.897, P < .001). Hepatic mRNA levels of YKL‐40 and TGF‐β correlated with the serum levels, confirming a hepatic source for the elevated serum levels. In conclusion, serial cytokine and fibrosis markers can accurately determine the rate at which fibrosis is progressing, identifying both those with rapid fibrosis and those with stable disease. (HEPATOLOGY 2006;43:771–779.)

Impact of Hepatitis C Virus on Immune Restoration in HIV-Infected Patients Who Start Highly Active Antiretroviral Therapy: A Meta-analysis

BACKGROUND There are conflicting data in the medical literature regarding the degree of immune restoration (as measured by CD4 cell count) in patients who commence highly active antiretroviral therapy (HAART) when coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV), compared with those with HIV infection alone. METHODS We performed a meta-analysis that compared CD4 cell count increases after HAART initiation in HCV-negative and HCV-positive patients who were infected with HIV. Published studies in the English-language medical literature that involved cohorts of HCV-negative and HCV-positive patients who were coinfected with HIV were obtained by searching the Medline, Embase Drugs and Pharmacology, and EBM Review-Cochrane Central Register of Controlled Trials databases. Data were extracted independently from relevant studies by 3 investigators and were used in a fixed-effects meta-analysis to determine the mean difference in the expected CD4 count change in the 2 groups. RESULTS Eight trials involving 6216 patients were analyzed. Patients with HIV-HCV coinfection had a mean increase in the CD4 cell count that was 33.4 cells/mm3 (95% CI, 23.5-43.3 cells/mm3) less than that for HIV-infected patients without HCV infection. The results of the meta-analysis were independent of any one study and were not influenced by the year in which HAART was started. CONCLUSIONS This meta-analysis shows that patients with HIV-HCV coinfection do, in fact, have less immune reconstitution, as determined by CD4 cell count after 48 weeks of HAART, than do patients with HCV infection alone. Future research should examine whether an impaired immunologic response corresponds with meaningful virologic and clinical outcomes.