Host and viral factors contributing to CD8＋ T cell failure in hepatitis C virus infection

Virus-specific CD8+ T cells are thought to be the major anti-viral effector cells in hepatitis C virus (HCV) infection. Indeed, viral clearance is associated with vigorous CD8+ T cell responses targeting multiple epitopes. In the chronic phase of infection, HCV-specific CD8+ T cell responses are usually weak, narrowly focused and display often functional defects regarding cytotoxicity, cytokine production, and proliferative capacity. In the last few years, different mechanisms which might contribute to the failure of HCV-specific CD8+ T cells in chronic infection have been identified, including insufficient CD4+ help, deficient CD8+ T cell differentiation, viral escape mutations, suppression by viral factors, inhibitory cytokines, inhibitory ligands, and regulatory T cells. In addition, host genetic factors such as the host’s human leukocyte antigen (HLA) background may play an important role in the efficiency of the HCV- specific CD8+ T cell response and thus outcome of infection. The growing understanding of the mechanisms contributing to T cell failure and persistence of HCV infection will contribute to the development of successful immunotherapeutical and -prophylactical strategies.     

Prospective study in 142 cases of hepatitis C virus infection

AIM:There is limited information on the natural history ofHCV infection in China.We investigated the outcome ofHCV infection after nine-year follow-up and the risk factorsin blood donors in China in order to provide the foundationfor prevention and therapy.METHODS:A total of 172 cases of HCV infection with anti-HCV positive and ALT abnormality were enrolled in thearchives when was screened blood in Hebei Province in1993.In them 142 blood donors were followed up till July2002.No antiviral treatment was applied to them duringthe period of infection.In the present study,anti-HCV,HCV-RNA and aminotransferase were detected and genotypingwas conducted by the method of restriction fragment lengthpolymorphism(RFLP).B-type ultrasound detection wasperformed in all the patients.Age,sex,alcohol consumptionand clinical symptoms were questioned.RESULTS:After nine years'follow-up,10.56%(15/142)of the cases were negative for anti-HCV and 16.42%(12/134)of them were negative for HCV-RNA.The genotypes 1b,2a and 1b/2a were 91.07%,6.25% and 2.68% respectively.Twelve cases(8.45%)were negative for both HCV RNAand anti-HCV.The rate of chronicity in this group was83.58%(112/134),and the rate of viral spontaneousresolution was 16.42%(22/134).The mean level of ALT,AST,γ-GT in HCV RNA positive cases was significantlyhigher than that in HCV RNA negative cases(P<0.001).The abnormal rate of ALT and/or AST in male donors wassignificantly higher than that in female donors(P=0.005).The rate of progression to liver cirrhosis from chronic hepatitisC was significantly higher in the cases of super-infectionwith HBV than that in the cases of single HCV infection.Overdose alcohol consumption promoted the progressionto chronicity.CONCLUSION:This area(Hebei Province)has a higherrate of chronicity in HCV infection,and measures shouldbe taken to prevent its progression to serious liver diseases,especially for patients super-infected with HCV and HBV.     

Amantadine in treatment of chronic hepatitis C virus infection?

Summary. Treatment of chronic hepatitis C (CHC) continues to be an important and growing challenge. As the response rate to FDA-approved treatment improved over the past decade, we are facing increasing number of difficult-to-treat patients such as those who have failed prior anti-viral therapy. The role of amantadine in the treatment of CHC remains unclear. Studies thus far have produced conflicting results, and type II error could not be excluded. This review summarized results published in the literature from 1997 to 2003, and reviewed the existing questions and controversies regarding the use of amantadine. Current literature suggests that amantadine is ineffective as monotherapy. Amantadine increased the sustained virologic response of certain treatment naïve patients when used in combination with interferon, and may be effective as an adjunct to interferon-based combination therapy in some patients who have failed or relapsed on prior therapy. Factors such as small sample size, patient characteristics, and differences in treatment protocols including amantadine preparation and duration of therapy might explain the conflicting observations of various studies. Further investigations are needed to define optimal dosing and formulation of amantadine, and its appropriate role in management of CHC infection.     

Occult hepatitis C virus infection： A new form of hepatitis C

INTRODUCTION The etiology of liver disease is unknown in approximately 10% of patients with abnormal results on liver function tests. Some authors have reported that occult hepatitis B virus could be the cause of a proportion of these cryptogenic chronic …     

Memory CD8＋ T cell differentiation in viral infection： A cell for all seasons

Chronic viral infections such as hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) are major global health problems affecting more than 500 million people worldwide. Virus-specific CD8+ T cells play an important role in the course and outcome of these viral infections and it is hypothesized that altered or impaired differentiation of virus- specific CD8+ T cells contributes to the development of persistence and/or disease progression. A deeper understanding of the mechanisms responsible for functional differentiation of CD8+ T cells is essential for the generation of successful therapies aiming to strengthen the adaptive component of the immune system.     

Characterization of B cell lymphoma in patients with Sjögren's syndrome and hepatitis C virus infection

OBJECTIVE: To characterize the clinical and immunologic patterns of expression, response to therapy, and outcome of patients with Sj?gren's syndrome (SS) and associated hepatitis C virus (HCV) infection who developed B cell lymphoma. METHODS: Various international reference centers constituted a multicenter study group with the purpose of creating a registry of patients with SS-HCV who developed B cell lymphoma. A protocol form was used to record the main characteristics of SS, chronic HCV infection, and B cell lymphoma. RESULTS: Twenty-five patients with SS-HCV with B cell lymphoma were included in the registry. There were 22 (88%) women and 3 (12%) men (mean age 55, 58, and 61 years at SS, HCV infection, and lymphoma diagnosis, respectively). The main extraglandular SS manifestations were cutaneous vasculitis in 15 (60%) patients and peripheral neuropathy in 12 (48%); the main immunologic features were positive rheumatoid factor (RF) in 24 (96%) and type II cryoglobulins in 20 (80%). The main histologic subtypes were mucosa-associated lymphoid tissue (MALT) lymphoma in 11 (44%) patients, diffuse large B cell lymphoma in 6 (24%), and follicular center cell lymphoma in 6 (24%). Fifteen (60%) patients had an extranodal primary location, most frequently in the parotid gland (5 patients), liver (4 patients), and stomach (4 patients). Twelve (52%) of 23 patients died after a median followup from the time of lymphoma diagnosis of 4 years, with lymphoma progression being the most frequent cause of death. Survival differed significantly between the main types of B cell lymphoma. CONCLUSION: Patients with SS-HCV and B cell lymphoma are clinically characterized by a high frequency of parotid enlargement and vasculitis, an immunologic pattern overwhelmingly dominated by the presence of RF and mixed type II cryoglobulins, a predominance of MALT lymphomas, and an elevated frequency of primary extranodal involvement in organs in which HCV replicates (exocrine glands, liver, and stomach).     

Is neutrophil gelatinase associated lipocalin useful in hepatitis C virus infection?

AIM: To evaluate neutrophil gelatinase associated lipocalin(NGAL) in patients infected by hepatitis C virus(HCV) before and during treatment with directly acting antivirals(DAAs).METHODS: NGAL was measured in a group of patients with chronic HCV infection ranked, at baseline, by age, gender, anti-hypertensive therapy, HCV viral load, liver fibrosis stage and, either at baseline or after 1 year, estimated glomerular filtration rate(e GFR). Then, NGAL and e GFR evolutions were monitored in a subgroup of patients who started antiviral therapy with DAAs. Differences of median NGAL levels were evaluated through Wilcoxon-Mann-Whitney test for nonparametric data. Differences in dichotomous variables were evaluated through χ~2 test. At baseline, a univariate regression analysis was conducted to verify if NGAL values correlated with other quantitative variables [age, fibrosis four(FIB-4), AST to platelet ratio index(APRI), and e GFR]. RESULTS: Overall, 48 patients were enrolled, 8 of them starting HCV treatment. At baseline, statistically significant differences were found in median NGAL values only between patients with e GFR 60 mL/min vs patients with e GFR ≥ 90 mL/min. Differences in NGAL were not significant among patients ranked by HCV viral load, FIB-4 score and APRI, when patients with NGAL 118.11 ng/d L were compared with those of NGAL ≤ 118.11 ng/d L, not statistically significant differences were present for age, gender, chronic kidney disease classification and liver fibrosis(P 0.05). Linear correlation was found between NGAL and both age(P = 0.0475) and e GFR(P = 0.0282) values. Not statistically significant predictions of NGAL at baseline were demonstrated for e GFR evolution 1 year later. Interestingly, in the 8 patients treated with DAAs, median NGAL significantly increased at week 12 compared to baseline(P = 0.0239).CONCLUSION: Our results suggest that NGAL should be further evaluated as an adjunct marker of kidney function in these patients.     

CD+4 CD+25调节性T细胞抑制持续性丙型肝炎病毒感染患者CD+4T细胞反应

目的探讨CD+4 CD+25调节性T细胞(CD+4 CD+25Treg细胞)在持续性HCV感染患者CD+4 T细胞下调中的意义.方法流式细胞术检测慢性丙型肝炎患者外周血中CD+4 CD+25Treg细胞的数量以及细胞内因子的合成;与正常人或患者CD+4 CD-25 T细胞共同培养,检测其抑制功能;RT-PCR检测Foxp3的mRNA表达.结果 CD+4 CD+25Treg细胞约占慢性丙型肝炎患者外周血中CD+4 T细胞的(13.5±1.8)%,高于正常对照(5.3±0.8)% (P=0.004);主要合成IL-10,高表达Foxp3;CD+4 CD+25Treg细胞显著抑制CD+4 T细胞的增殖,以及合成IFNγ,并且抑制活性较正常人增高(P=0.034),这种作用不依赖IL-10和转化生长因子β.结论持续性HCV感染患者CD+4 CD+25Treg细胞表达增加,抑制活性增强,特异性抑制Th1反应.     

HBV感染后外周血CD4+CD25+Foxp3+调节性T细胞与疾病进展的相关性

目的:探讨HBV感染者外周血CD4~ CD25~ Fox- p3~ 调节性T细胞水平与HBV感染后疾病进程的相关性.方法:HBV感染者136名及健康对照40名,应用流式细胞仪胞内染色技术检测外周血CD4~ CD25~ Foxp3~ 调节性T细胞表达,结合HBV感染者临床情况进行分析.结果:HBV感染者外周血CD4~ CD25~ Foxp3~ 调节性T细胞表达率较健康对照组显著增高(7.48%±1.03% vs 3.58%±0.71%,P<0.01);慢性乙肝组与慢性重型乙肝组相比,外周血CD4~ CD25~ Foxp3~ T调节细胞的表达率有明显差异(6.55%±1.26% vs 8.65%±2.58%,P<0.05);HBV病毒载量的对数值与外周血CD4~ CD25~ Foxp3~ T调节细胞的表达率之间存在正相关(r=0.332,P<0.01).结论:HBV感染者外周血CD4~ CD25~ Foxp3~ 调节性T细胞水平与疾病进展明显相关.     

Reversal of nonstructural protein 3-specific CD4(+) T cell dysfunction in patients with persistent hepatitis C virus infection

Hepatitis C virus (HCV)-specific T cell responses are essential for HCV control, and chronic infection is characterized by functionally altered antigen-specific T cells. It has been proposed that the early inactivation of specific CD4(+) T cell responses may be involved in establishment of HCV persistence. We have investigated whether HCV-specific CD4(+) T cells dysfunction can be reversed in vitro. Nonstructural protein 3 (NS3) and core-specific CD4(+) T cells from eight chronically infected and eight spontaneously resolved HCV individuals were selected through transient CD154 (CD40 ligand) expression, and their functional profile (IFN-γ, IL-2, TNF-α, IL-10 and IL-4 production by enzyme-linked immunospot assay, cytometric bead array and intracellular cytokine staining, and proliferation by carboxy-fluorescein diacetate succinimidyl ester dilution assay) was determined both ex vivo and after in vitro expansion of sorted CD154-expressing cells in the absence of specific antigen in IL-7/IL-15-supplemented medium. Ex vivo bulk CD4(+) T cells from chronic patients expressed CD154 in most cases, albeit at lower frequencies than those of resolved patients (0.11%vs 0.41%; P = 0.01), when stimulated with NS3, but not core, although they had a markedly impaired capacity to produce IL-2 and IFN-γ. Antigen-free in vitro expansion of NS3-specific CD154(+) cells from chronic patients restored IFN-γ and IL-2 production and proliferation to levels similar to those of patients with spontaneously resolved infection. Hence, NS3-specific CD4(+) T cell response can be rescued in most chronic HCV patients by in vitro expansion in the absence of HCV-specific antigen. These results might provide a rationale for adoptive immunotherapy.     

Hepatitis C virus eradication associated with hepatitis B virus superinfection and development of a hepatitis B virus specific T cell response

BACKGROUND/AIMS: Specific T cell responses during acute hepatitis B and during chronic hepatitis C have been described in detail. However, the T cell responses during the rare setting of acute hepatitis B virus (HBV) infection in the course of chronic hepatitis C that eventually lead to clearance of both viruses are completely unknown. METHODS: We analyzed the virus specific CD4+ and CD8+ T cell response during an acute HBV superinfection in a patient with chronic hepatitis C. RESULTS: The patient eliminated hepatitis C virus (HCV)-RNA and HBV-DNA from serum soon after the clinical onset of acute hepatitis B. The HBV specific T cell response found in this patient corresponds to the typical response that has been described in acute hepatitis B without chronic HCV infection. In contrast the hepatitis C specific immune response was similar to that generally found in chronic hepatitis C despite the fact that the patient also eliminated HCV-RNA. CONCLUSIONS: We hypothesize that the acute HBV infection induced a HBV specific T cell response which was associated with elimination HBV DNA and HCV-RNA, the latter possibly by bystander mechanisms, e.g. via secretion of cytokines. If such a non-specific bystander mechanism which has proven to be effective in the experimental setting and which is formally described here for a single patient can be shown to be a more general phenomenon, it may support the approach with new antiviral strategies, e.g. the induction of non-specific defense mechanisms against HCV.     

CD4+CXCR5+ T cells activate CD27+IgG+ B cells via IL-21 in patients with hepatitis C virus infection

BACKGROUND: Chronic hepatitis C virus (HCV) infection causes the skewing and activation of B cell subsets, but the characteristics of IgG+ B cells in patients with chronic hepa-titis C (CHC) infection have not been thoroughly elucidated. CD4+CXCR5+ follicularhelperT(Tfh)cells,viainterleukin (IL)-21 secretion, activate B cells. However, the role of CD4+CXCR5+T cellsintheactivationof IgG+ BcellsinCHCpatientsis not clear.
METHODS: The frequency of IgG+ B cells, including CD27?IgG+B and CD27+IgG+ B cells,the expression of the activation markers (CD86 and CD95) in IgG+ B cells, and the percentage of circu-lating CD4+CXCR5+ T cells were detected by flow cytometry in CHC patients (n=70) and healthy controls (n=25). The con-centrations of serum IL-21 were analyzed using ELISA. The role of CD4+CXCR5+ T cells in the activation of IgG+ B cells was investigated using a co-culture system.
RESULTS: A significantly lower proportion of CD27+IgG+ B cells with increased expression of CD86 and CD95 was observed in CHC patients.The expression of CD95 was negatively correlated with the percentage of CD27+IgG+ B cells, and it contributed to CD27+IgG+ B cell apoptosis. Circulating CD4+CXCR5+ T cells and serum IL-21 were significantly increased in CHC patients. Moreover, circulating CD4+CXCR5+ T cells from CHC patients induced higher expressions of CD86 and CD95 in CD27+IgG+B cells in a co-culture system; the blockade of the IL-21 decreased the expression levels of CD86 and CD95 in CD27+IgG+ B cells.
CONCLUSIONS: HCV infection increased the frequency of CD4+CXCR5+ T cells and decreased the frequency of CD27+IgG+B cells. CD4+CXCR5+ T cells activated CD27+IgG+ B cells via the secretion of IL-21.     

乙型病毒性肝炎的免疫动力学

乙型肝炎的发病机制主要是机体清除乙型肝炎病毒(hepatitis B virus,HBV)而引发的细胞免疫病理改变,机体对病毒的免疫应答有赖于一系列免疫活性细胞的相互作用.目前国内外主要就HBV感染控制者和感染持续者间的免疫差异原因进行研究.本文就乙型肝炎病毒感染状态下机体控制HBV感染下各相关免疫细胞间的作用机制以及...     

Effect of HLA class II genotype on T helper lymphocyte responses and viral control in hepatitis C virus infection

Hepatitis C virus (HCV) infection is very common worldwide, but has a broad range of outcomes. A minority of patients are able to clear infection spontaneously, and this is thought to be due to the emergence and maintenance of effective cell-mediated immunity, particularly CD4+ T lymphocyte responses. Furthermore, genetic studies have indicated that HLA class II genotype strongly influences the outcome of infection. We have therefore investigated the influence of the protective HLA class II haplotype (DQB1*0301, which is in tight linkage disequilibrium with DRB1*1101) on the CD4+ T lymphocyte responses to HCV. We observe a strong association between this genotype and maintenance of a multispecific CD4+ T helper response. The effect on T helper responses was also maintained after combination interferon-α/ribavirin therapy, although the latter influenced the pattern of viral antigens to which patients responded. This is the first disease in which an association of HLA genotype with clinical outcome has been linked to an alteration of the immunological phenotype. The selection of protective peptides in those with the favourable HLA class II genotype may point in the direction of suitable vaccine candidates.     

CD154, a marker of antigen-specific stimulation of CD4 T cells, is associated with response to treatment in patients with chronic HCV infection

Summary. CD4 T‐cell function is crucial for the eradication of HCV, and insufficient function is observed in chronic carriers. The monitoring of T‐cell responses is complicated by the scarcity of antigen‐specific T cells and the relative inefficiency of virus‐specific T cells to produce effector cytokines. CD154 is a marker of activation expressed on T cells induced through their T‐cell receptor. We analysed CD4 T‐cell responses in 72 patients with chronic or resolved HCV infection (23 treatment naïve, 49 treatment experienced, including 16 who had achieved a sustained response). In an additional prospective protocol, 20 of the chronically infected patients were analysed before and after 8–12 weeks of combination therapy with peg‐interferon‐α and ribavirin. T‐cell responses were measured by detecting the expression of CD154 and Th1 cytokines after stimulation with recombinant HCV proteins and were correlated with pretreatment status and outcome of therapy. Broader T‐cell responses were observed in treatment naïve than in experienced patients, while the outcome of a preceding therapy regimen did not influence T‐cell responses. In the prospective cohort, an on‐treatment increase in CD154+ cytokine? T‐cell activity was associated with response to treatment, while a decrease was observed in nonresponders. Stronger antigen‐independent activity of CD154+ cytokine+ T cells was observed in responders than in nonresponders. Our data indicate that CD154 as a marker of activation of CD4 T cells is a suitable tool for the analysis of T‐cell responses in patients with HCV infection.