Neutralizing antibodies in hepatitis C virus infection

Hepatitis C virus (HCV) is a major cause of hepatitis world-wide. The majority of infected individuals develop chronic hepatitis which can then progress to liver cirrhosis and hepatocellular carcinoma. Spontaneous viral clearance occurs in about 20%-30% of acutely infected individuals and results in resolution of infection without sequaelae. Both viral and host factors appear to play an important role for resolution of acute infection. A large body of evidence suggests that a strong, multispecific and long-lasting cellular immune response appears to be important for control of viral infection in acute hepatitis C. Due too the lack of convenient neutralization assays, the impact of neutralizing responses for control of viral infection had been less defined. In recent years, the development of robust tissue culture model systems for HCV entry and infection has finally allowed study of antibody-mediated neutralization and to gain further insights into viral targets of host neutralizing responses. In addition, detailed analysis of antibody-mediated neutralization in individual patients as well as cohorts with well defined viral isolates has enabled the study of neutralizing responses in the course of HCV infection and characterization of the impact of neutralizing antibodies for control of viral infection. This review will summarize recent progress in the understanding of the molecular mechanisms of antibody-mediated neutralization and its impact for HCV pathogenesis.     

Targeted inhibition of hepatitis C virus–directed gene expression in human hepatoma cell lines

Background & Aims: The 5'-nontranslated region (NTR) of hepatitis C virus (HCV) contains important elements that control HCV translation. The aim of this study was to determine whether antisense oligonucleotides against the NTR of the HCV genome can be targeted to inhibit HCV gene expression. Methods: Antisense oligonucleotides directed against a sequence in the internal ribosomal binding site of the NTR (anti-III) and a portion of the NTR overlapping the core protein translational start site of HCV (anti-IV) were prepared. In transient transfections of a plasmid containing a luciferase gene immediately downstream from an HCV NTR insert, oligonucleotides anti-III and anti-IV in the form of asialoglycoprotein–polylysine complexes were administered to Huh7 cells, and luciferase activity generated by cytomegalovirus (CMV) HCVluc was measured. Results: Anti-III inhibited luciferase activity by 75% and 99% at 0.01 μmol/L and 0.1 μmol/L, respectively. Similarly, anti-IV inhibited luciferase activity 88% and 99% at 0.01 μmol/L and 0.1 μmol/L, respectively. In cell lines stably transfected with CMV HCVluc plasmid, complexed anti-III inhibited luciferase activity in Huh7 cells by 20% at 10 μmol/L and 85% at 60 μmol/L, and was competable by an excess of asialoglycoprotein. Conclusions: Antisense oligonucleotides that bind to the NTR of HCV can be targeted by receptor-mediated endocytosis, and they specifically inhibit HCV-directed protein synthesis under intracellular conditions.GASTROENTEROLOGY 1998;114:1304-1312     

Anti-Clq antibodies in patients with chronic hepatitis C infection

OBJECTIVE: Extrahepatic autoimmune features of HCV infection include autoantibody production and the development of mixed cryoglobulinemia. Anti-Clq antibody, detected with high frequency in systemic lupus erythematosus and hypocomplementemic urticarial vasculitis, may have a direct pathogenic role in complement mediated autoimmune diseases. In this study, we investigate the prevalence of anti-Clq antibody in a population of patients with chronic HCV infection. METHODS: Serum was obtained from a group of 50 patients with chronic HCV infection and control groups comprised of patients with SLE, rheumatoid arthritis (RA), scleroderma (PSS), Sj?gren's syndrome (SS), mixed connective tissue disease (MCTD), and healthy individuals. RESULTS: Anti-Clq antibody was detected in 38% of HCV patients compared with 2% of healthy controls (p < 0.0001). Levels were also significantly elevated in patients with SLE (61%), RA (20%), PSS (15%), SS (15%) and MCTD (15%). CONCLUSION: In addition to numerous other autoantibodies, patients with chronic HCV infection exhibit increased production of anti-Clq IgG antibodies. This observation may have implications for the pathogenesis of the mixed cryoglobulinemic vasculitis syndrome.     

Extrahepatic immune related manifestations in chronic hepatitis C virus infection

The association of chronic hepatitis C with immune related syndromes has been frequently reported. There is a great range of clinical manifestations affecting various systems and organs such as the skin, the kidneys, the central and peripheral nervous system, the musculoskeletal system and the endocrine glands. Despite the high prevalence of immune related syndromes in patients with chronic hepatitis C, the exact pathogenesis is not always clear. They have been often associated with mixed cryoglobulinemia, a common finding in chronic hepatitis C, cross reaction with viral antigens, or the direct effect of virus on the affected tissues. The aim of this review is to analyze the reported hepatitis C virus immune mediated syndromes, their prevalence and clinical manifestations and to discuss the most supported theories regarding their pathogenesis.     

Antiphospholipid antibodies and hepatitis C virus infection in Iranian thalassemia major patients

Although the precise nature of Antiphospholipid antibodies is still not clearly defined, they are known to have association with thromboembolic events and have been found in hepatitis C virus (HCV) infection. Moreover, high prevalence of HCV infection and thrombotic risk is described in thalassemia. We aimed at investigating the prevalence of anticardiolipin antibodies (aCLAbs), lupus anticoagulant (LA), and their relation with HCV infection in Iranian thalassemic patients. Presence of anti-HCV antibody, serum HCV-RNA, aCLAbs, and LA activity was determined in 131 patients with thalassemia major (male/female: 63/68 aged 3-29 years) registered at thalassemia unit, Dastgheib Hospital, Shiraz, Iran. Sixty-one healthy controls were also included. Anti-HCV antibody was positive in 24 (18.3%), IgG aCLAbs in 56 (42.7%), and LA activity in 9 (6.9%) patients. 87.5% of patients positive for aCLAbs had a low titer of aCLAbs. Although none of the participants had a previous history of thrombosis, higher prevalence of aCLAbs was detected in thalassemic patients compared with controls. No significant difference in the prevalence of aCLAbs was found between HCV-infected and noninfected patients. A high prevalence of aCLAbs, the majority in low titers, was detected in Iranian thalassemic patients irrespective of previous history of thrombosis and presence of HCV infection.     

Lupus anticoagulant, anticardiolipin antibodies and hepatitis C virus infection in thalassaemia

Anticardiolipin antibodies (ACA) and lupus anticoagulant (LA) have been detected in patients with hepatitis C virus (HCV) infection and have been associated in autoimmune diseases (i.e. systemic lupus erythematosus) with an increased risk of thromboembolic events. Because of the high prevalence of HCV infection and the thrombotic risk described in thalassaemia we decided to investigate the prevalence of ACA and LA in a cohort of 68 thalassaemia patients. We found a high prevalence (34%) of β2-glycoprotein I independent ACA in our thalassaemia patients which was related to HCV infection. None of patients developed any complications related to antiphospholipid antibodies (APL); therefore the clinical significance of positivity for APL in patients with HCV infection is at present unclear. In conclusion, the results of our study indicate that ACA in the serum of HCV-infected thalassaemic patients exhibit the characteristics of natural autoantibodies rather than those of the pathogenic autoantibodies that are found in patients with systemic lupus erythematosus.     

Virologic factors related to interferon-alpha-induced thyroid dysfunction in patients with chronic hepatitis C

OBJECTIVE: Hepatitis C virus (HCV), being reported to be associated with a high prevalence of serological markers of autoimmunity in HCV-infected patients, and possibly sharing partial sequences in amino acid segments with thyroid tissue antigens, may be associated with interferon-alpha (IFN-alpha)-induced thyroid dysfunction in chronic hepatitis C patients. We conducted this study to clarify the issue. DESIGN AND METHODS: One hundred and fifty chronic hepatitis C patients with normal baseline thyroid function were treated with IFN-alpha 2a, 2b and n1 (3-6 million Units three times weekly for 24 weeks). Pretreatment sera were tested for HCV genotype and HCV RNA levels. Serum thyrotropin, total thyroxine and free thyroxine index were performed every 4 weeks for 24 weeks followed by every 8 weeks for another 24 weeks. RESULTS: Twenty-one (14.0%) patients developed early thyroid dysfunction (abnormal thyroid function during the first 3 months of therapy). Female gender, lower HCV RNA levels, IFN-alpha n1 and a lower IFN-alpha dose were significantly associated with early thyroid dysfunction. On multivariate analysis, gender, IFN-alpha preparation and HCV RNA levels were the significant factors associated with early thyroid dysfunction. Seven (4.7%) patients developed thyroid dysfunction during the second 3 months of IFN-alpha therapy. Taken together, 18.7% patients developed thyroid dysfunction. Female, mixed HCV genotype infection and lower HCV RNA levels were significantly associated with thyroid dysfunction. However, only gender remained significantly associated with IFN-alpha-induced thyroid dysfunction in multivariate analysis. CONCLUSIONS: The virologic features of HCV may be associated with thyroid dysfunction in chronic hepatitis C patients treated with IFN-alpha. Nevertheless, gender still plays the most important role in IFN-alpha-induced thyroid dysfunction.     

Virus‐neutralizing antibodies to hepatitis C virus

For a long time, the lack of an appropriate cell culture system has hampered the study of neutralizing antibody responses against hepatitis C virus (HCV). However, the last decade has seen the development of several model systems that have significantly advanced our understanding of viral entry and antibody neutralization. Studies of acutely infected patients suggest that a strong and early production of neutralizing antibodies may contribute to control the virus during the acute phase of HCV infection and facilitate viral elimination by cellular immune responses. It also emerges that the early antibody response mainly targets hypervariable region 1 (HVR1) of the envelope glycoprotein E2. This host response can lead to viral escape from neutralization by rapid amino acid changes in this hypervariable region. In contrast, cross‐reactive neutralizing antibodies seem to appear later during HCV infection, and several mechanisms contribute to reduce their accessibility to their cognate epitopes. These include the masking of major conserved neutralizing epitopes by HVR1, specific N‐linked glycans and the lipid moiety of the viral particle. Other potential mechanisms of evasion from the neutralizing antibody response include a modulation by high‐density lipoproteins and interfering antibodies as well as the capacity of the virus to be transferred by cell‐to‐cell contacts. Finally, the recent identification of several highly conserved neutralizing epitopes provides some opportunities for the design and development of vaccine candidates that elicit a protective humoral immune response.     

Antiplatelet antibodies contribute to thrombocytopenia associated with chronic hepatitis C virus infection

Abstract

Thrombocytopenia is one of the most frequent hematological manifestations of hepatitis Cvirus (HCV) infection; which typically worsens with progression of the liver disease and can become a major clinical complication. Several mechanisms have been postulated to explain thrombocytopenia in HCV hepatic patients, including immune mechanisms. The aim of the present work is to investigate the role of immune mechanisms as a causative agent of thrombocytopenia in HCV hepatic patients. The study included 50 hepatic patients with HCV infection (30 with thrombocytopenia and 20 with normal platelets counts). Platelets associated glycoprotein specific antibodies were evaluated by flow cytometry and confirmed by quantitative monoclonal immobilization of platelet antibodies (MAIPA). The frequency of platelet associated immunoglobulin (PAIg) in thrombocytopenic HCV positive hepatic patients by FCM was 86·7, 83·3, 46·7 and 33·3% for total PAIg, PAIgG, PAIgM and PAIgA respectively. MAIPA found platelet specific antibodies in 26/30 (86·7%) of patients. The most likely target antigen for platelets antibodies were glycoprotein (GP) IIb/IIIa (30%), followed by GP IIIa (20·5), GP IIb (13·3%), GPIb (13·3%), then GPIa (10%). The platelets count was inversely correlated to the levels of platelets GP specific antibodies (r=?0·42, p=0·024), and significantly parallel to spleen size (p=0·024). Platelet associated glycoprotein specific antibodies represent a common mechanism inducing thrombocytopenia in patients with chronic HCV infections.     

The development of antiphospholipid antibodies in haemophilia is linked to infection with hepatitis C

Summary In haemophilia the presence of antibodies to antiphospholipid has been linked with HIV infection, but other possibilities have not been fully explored and the specificity for various phospholipids not established. In order to investigate further the pathogenesis and clinical significance of these antibodies, we have determined IgG and IgM antibodies to a variety of phospholipids, including cardiolipin, in the serum of 52 haemophiliacs, and related our findings to the presence of antibodies to HIV and hepatitis C virus (HCV), as well as to clotting factor concentrate usage and blood markers of liver biochemistry. Our results demonstrate that the presence of infection with hepatitis C virus is strongly associated with raised serum levels of antiphospholipid antibody even in the absence of HIV infection. They suggest that earlier conclusions on the relationships of antiphospholipid to HIV infection in haemophilia should be revised and that chronic infection with the hepatitis C virus should be added to the list of infective cause for the development of angtiphospholipid antibody.     

慢性丙型肝炎患者幽门螺杆菌感染及其相关因素分析

目的:探讨幽门螺杆菌(H pyloH)在慢性丙型肝炎中的作用.方法:采用Hpylor流行病学诊断标准检测血清anti-Hpylori-IgG,来判定是否存在Hpylori 感染,实时荧光定量聚合酶链反应(FQ-PCR)方法检测血清中HCV RNA的含量,聚合酶链反应.微板核酸杂交.酶联免疫测定法检测血清中HCV基因型.结果:HpyloN感染率在慢性丙型肝炎组、丙型肝炎肝硬化组和合并肝癌组明显高于健康对照组(55.5%、76.5%、78.6%VS 43.4%,P＜0.05),且随着病变程度的加重,Hpylon感染率增加.不同HCV载量的慢性丙型肝炎患者Hpylon感染率均增加.基因1a型、1b型、2a型和2b型患者HpyloN感染率分别为59.5%、66.7%、65.0%和59.2%,各基因型之间比较无显著性差异.结论:慢性丙型肝炎患者幽门螺杆菌感染率明显增加,H pylori在慢性丙型肝炎向肝硬化和肝癌的发展过程中可能与HcCV发挥协同作用.     

Interferon-induced thyroid dysfunction in chronic hepatitis C

Background:  Treatment of chronic hepatitis C with interferon is known to be associated with thyroid dysfunction (TD) in 5–14% of patients. We studied the incidence, types, outcome and risk factors predictive of thyroid dysfunction.
Methods:  A retrospective analysis was performed on all patients treated with interferon alpha (IFN) or pegylated interferon alpha (PEG-IFN) ± ribavirin (RBV), who developed abnormal thyroid function tests (TFTs). These cases were compared with treatment-matched controls to identify factors predictive of thyroid dysfunction. Statistical methods consisted of: χ² test, Fischer's exact test, Welch's t -test, and multivariate analysis.
Results:  From a total of 511 patients, 45 cases with TD were identified (8.8%). Pegylated interferon alpha was associated with higher rates of TD than IFN (14.1% vs 6.0%, P  = 0.0029). Female sex (OR 5.6, 95% CI 1.1–7) and Asian ethnicity (OR 2.7, 95% CI 1.4–22) were independent predictors of developing TD. Cytology was obtained in 13 patients: benign follicular pattern (8); thyroiditis (3); and normal (2). Thyroid peroxidase (TPO) antibodies ( P  = 0.004) and earlier onset of dysfunction ( P  = 0.03) were associated with need for treatment. Sixteen patients had persistent TD by the end of the follow-up period, predicted by female sex, non-Asian ethnicity, prior history of TD and TPO antibodies.
Conclusions:  Pegylated interferon alpha, female sex and Asian ethnicity are independent risk factors for TD. Thyroid peroxidase antibodies and earlier TD within the course of IFN are associated with the requirement for treatment. Thyroid function tests should be monitored during and after IFN-based therapy. The most common cytological finding is a benign follicular pattern.     

Comparison of duodenal with jejunal biopsy and aspirate in chronic human immunodeficiency virus–related diarrhea

Objectives: In human immunodeficiency virus (HIV)-infected patients with chronic unexplained diarrhea, upper endoscopy with small bowel biopsy and aspirate is often performed to identify treatable pathogens. The purpose of this study was to compare the diagnostic yield of duodenal with jejunal biopsy and aspirate.
Methods: All HIV-infected patients with chronic unexplained diarrhea who were evaluated by upper endoscopy at Bellevue Hospital Center between January 1992 and January 1997 were identified. Data were collected by reviewing patient charts, endoscopy reports, and pathology records.
Results: During the 5-yr study period, 442 patients underwent upper endoscopy with sampling of the duodenum (  N = 173  ) or jejunum (  N = 269  ). A pathogen was identified in 123 patients (27.8%). Microsporidia was the most common organism detected (12.2%). The diagnostic yield of jejunal biopsy and aspirate was significantly higher than that obtained from the duodenum (32.3% vs 20.8%,   p = 0.009  ). Small bowel aspirates detected a pathogen in only 1.8% of patients evaluated, and there was no difference in the yield of duodenal and jejunal aspirates (1.3% vs 2.1%,   p = 0.7  ). Patients with a CD4 count of < 100 cells/mm³ were significantly more likely to have a pathogen identified than those with higher CD4 counts (38.8% vs 7.1%,   p < 0.0001  ).
Conclusions: Upper endoscopy with small bowel biopsy and aspirate identifies a pathogen in 27.8% of individuals with HIV-related chronic unexplained diarrhea. In this patient population, jejunal biopsies acquired by enteroscopy are superior to those obtained from the duodenum. Small bowel aspirates are of little value in the workup of chronic HIV-related diarrhea.     

Treatment of hepatitis C infection

HCV infection is one of the leading causes of chronic liver disease worldwide,and it results in cirrhosis, liver failure, and HCC. As a result, hepatitis C cirrhosis has become the principal indication for liver transplantation. Ironically,HCV infection can be cured with available antiviral therapies, but only a minority of infected persons has ever been treated. The current standard of therapy isa combination of PEG-IFNalpha and ribavirin, which produces high rates of SVRs(absence of detectable HCV RNA at least 24 weeks after cessation of therapy):42% to 56% in genotype 1 and 75% to 84% in genotypes 2 and 3. Recent reports indicate that the less frequent genotypes 4, 5, and 6 also are responsive to combination therapy. Recommendations for treatment of conventional and special patient populations were reviewed in detail. Newer therapeutics that are entering clinical trials provide hope that SVRs may be possible in patients who are difficult to treat and in nonresponders to current therapy.     

肝特异性自身抗体与丙型肝炎病毒感染的关系

本研究探讨了HCV感染时体内产生免疫应答并出现多种自身抗体的特点,试图通过检测分析HCV感染与自身抗体的相关性,对丙型肝炎的诊断及治疗提供一些实验数据.