Hepatitis C virus in autoimmune liver disease in the UK: aetiological agent or artefact?

The association of hepatitis C virus infection and thyroid disease: A systematic review and meta-analysis

Previous studies have reported that hepatitis C virus (HCV) infection may increase the risk of thyroid disease (TD) even thyroid cancer (TC), but quantitative assessments of risk were rare and the results were not consistent. The purpose of this study was to evaluate the impact of HCV infection on TD and TC, and provide clues to explore the relationship between HCV infection and TD and TC. The literature retrieval was performed up to August 20th, 2021 in the database of PubMed, Cochrane library, Web of Science, China National Knowledge Infrastructure and Wang Fang. The risk of HCV for TD or TC was expressed with odds ratio (OR) and 95% confidence intervals (CI). Subgroup analysis was used to explore the source of heterogeneity. Six articles (three studies published as article and three studies published as abstract) were included in this meta-analysis, with a total of 5398 controls and 1925 cases of hepatitis C. The results of meta-analysis found that HCV infection were significantly associated with an increased risk of TD (sum OR = 1.80, 95% CI = 1.54-2.10, P <  0.001, I² = 74.3%) and TC (sum OR = 16.36, 95% CI = 4.65-57.62, P < 0.001, I² = 0%). HCV infection may increase the risk of TD and TC. More work is needed in the future to establish a causal role, however an awareness of the possibility of increased risk of TD and TC may lead to earlier diagnosis and better outcomes in patients with hepatitis C.

Direct effects of hepatitis C virus on the lymphoid cells

It has been reported that the direct binding of hepatitis C virus (HCV) and/or the replication of HCV in the extrahepatic organs and, especially, lymphoid cells, might affect the pathogenesis of extrahepatic diseases with HCV infection. More than one decade ago, several reports described the existence of HCV-RNA in peripheral blood mononuclear cells. Moreover, many reports describing the existence of HCV in B lymphocytes and B cell lymphoma have been published. In addition to B lymphocytes, it was reported that HCV replication could be detected in T lymphocytes and T cell lines. Among the extrahepatic diseases with HCV infection, mixed cryoglobulinemia-related diseases and autoimmune-related diseases are important for understanding the immunopathogensis of HCV persistent infection. Moreover, HCV persistent infection can cause malignant lymphoma. The biological significance of lymphotropic HCV has not yet become clear. However, several candidates have been considered for a long time. One is that lymphotropic HCV is an HCV reservoir that might contribute to the recurrence of HCV infection and difficult-to-treat disease status. The other important issue is the carcinogenesis of the lymphoid cells and disturbances of the immune responses. Therefore, the extrahepatic diseases might be induced by direct interaction between HCV and lymphoid cells. In this article, we summarize various studies showing the direct effect of HCV on lymphoid cells and discuss the biological significance of lymphotropic HCV.

Poor performance of hepatitis C antibody tests in hospital patients in Uganda

Most hepatitis C testing in Uganda is performed using commercial rapid strip assays (RSA) to detect antibodies to hepatitis C virus (anti-HCV), rather than enzyme immunoassays (EIA). The prevalence of hepatitis C antibodies in a Ugandan hospital population was determined using both methods to test their accuracy using nucleic acid testing (NAT) as a reference. Sera from 380 consecutive hospitalized Ugandan patients were tested for anti-HCV using an RSA in Uganda, with subsequent automated third-generation EIA testing in the United States, followed by NAT. Recombinant immunoblot assays (RIBA) were used as a supplementary test to detect anti-HCV epitopes. Overall, anti-HCV was detected in 48/380 (13%) by one or both antibody tests. Anti-HCV was detected in 19 (5.0%) patients by RSA and in 33 (8.7%) patients by EIA; only four patients were anti-HCV positive by both methods. Fourteen of the 48 anti-HCV positive patients had detectable serum HCV RNA, 7 each by bDNA assay or by PCR. RSA detected only 7 of 14 HCV RNA positive sera. Of 29 RNA negative but anti-HCV positive patients tested by RIBA, only two were anti-HCV positive; 27 were anti-HCV negative or indeterminate. Anti-HCV testing by RSA and/or EIA was neither sensitive nor specific for detection of ongoing HCV infection in hospitalized Ugandan patients. Our findings underscore the importance of confirmatory nucleic acid testing, which, despite its increased cost, appears essential to manage African patients with HCV.

Autoimmunity and viruses

Although viruses are commonly cited as triggers for autoimmune disease, the actual mechanisms by which they initiate autoimmunity are unknown. Molecular mimicry is the most popular hypothesis, and it proposes that viral antigens that share homologies with host antigens generate an immune response that damages host tissue. The viral antigen may not be needed for perpetuation of the disease, and cross-reacting immune responses can involve humoral, cellular, or both types of reactivity. Linear and conformational epitopes may be involved, and foreign antigens do not need to share exact amino acid sequences with self-proteins to activate autoreactive T cells. Bystander effects can enhance the autoimmune process if previously sequestered or cryptic antigens are exposed to the immune system, and superantigens that are produced by the pathogen and are not MHC restricted can result in marked polyclonal activation of CD4 and CD8 T cells. Future studies must differentiate the targets of pathologic immunity and distinguish self-antigens from infectious nonself-antigens. Transgenic animal models of AIH are needed to assess the pathogenicity of the antigenic targets.

Autoimmune disease is not a feature of hepatitis C infection in Ireland

To determine the prevalence of autoimmune disease, autoantibody positivity, or both in Irish persons with hepatitis C, we surveyed 98 such patients (55 recipients of anti-D, 25 intravenous drug abusers, and 18 blood transfusion recipients). We studied them clinically and tested for anti-nuclear, anti-smooth muscle, and anti-mitochondrial, liver-kidney microsomal, thyroid microsomal, thyroid globulin, and gastric parietal antibodies; and also for rheumatoid factor. In the anti-D antibody group (all female), two patients reported generalized musculoskeletal symptoms but had no demonstrable physical signs. We did not find cryoglobulins in any patient. We detected thyroid microsomal antibodies in only 6 of 55 (10.9%) patients. (In two of these, thyroid globulin antibodies were also positive). These patients were all clinically euthyroid, but two had borderline low-normal thyroid function tests. Titers for anti-nuclear antibodies were weakly positive in 5 of 55 (9.1%) patients, and gastric parietal antibodies were positive in 5 of 55 (9.1%) patients. In particular, we noted no antibodies to liver-kidney microsome. Rheumatoid factor was detected in eight patients. Forty-seven of 55 patients were genotype 1b, and 8 of 55 were genotype 3. In the intravenous drug abusers (8 women, 17 men), we detected no autoantibodies. Seven of the 25 genotypes were tested; three were genotype 3 and four were genotype 1b. In the transfusion group (10 women, 8 men), we detected no autoantibodies apart from weak anti-nuclear antibody Titers (1:10), which we found three patients. Five of 10 genotypes tested were of genotype 3 and the other five were of genotype 1b. These findings suggest that in Irish patients with hepatitis C, neither genotype nor source (and dose) of inoculum contributes to the development of autoimmune disease. How hepatitis C virus is associated with autoimmune disease in other studies remains unknown. The answer may, at least in part, be found in genetic; HLA typing studies should provide useful information.

Chronic non-A, non-B, non-C hepatitis: is hepatitis G/GBV-C involved?

BACKGROUND

Hepatitis G virus/GBV-C is a recently discovered virus, and its relevance in chronic hepatitis is still debated.

METHODS

We have previously described 127 long-term-studied and well-characterized patients with chronic non-A, non-B hepatitis (NANBH). Ninety-one (71.7%) were positive for hepatitis C virus antibodies (anti-HCV) in a first-generation anti-HCV enzyme-linked immunosorbent assay (ELISA). We now reanalyzed the same group of patients and added a third-generation anti-HCV ELISA and recombinant immunoblot assay and, in negative patients, also polymerase chain reactions for hepatitis C virus RNA, hepatitis GBV-C RNA, and hepatitis B virus DNA. Additional tests for autoimmune hepatitis types 2 and 3 were also included.

RESULTS

Anti-HCV were detected in 114 of the 123 evaluable patients (92.7%). Of the remaining nine anti-HCV-negative patients one had misdiagnosed primary biliary cirrhosis, and two had autoimmune hepatitis type 3. None of the anti-HCV-negative patients were hepatitis GBV-C RNA-, HCV RNA-, or HBV DNA-positive. Thus, 114 of 120 NANBH patients (95.0%) had chronic hepatitis C. None of the remaining six patients had received blood transfusions or was a drug addict, and two of them were successfully treated with steroids.

CONCLUSIONS

Hepatitis G/GBV-C as a single cause of chronic non-A, non-B hepatitis is uncommon, and in all patients with parenteral risk factors hepatitis C was detected.

Granulomatous cholangitis in chronic hepatitis C: a new diagnostic problem in liver pathology

A case of chronic hepatitis C at the pre-cirrhotic stage complicated with hepatocellular carcinoma is reported. The patient, a 64 year old female, showed elevated levels of serum alkaline phosphatase and immunoglobulin M. Antimitochondrial antibodies were negative by indirect immunofluorescence. Western blotting using beef heart mitochondria and recombinant polypeptides coding for mitochondrial antigens revealed that the patient's serum was positive only for the E2-subunit of the branched chain ketoacid dehydrogenase complex. In the non-neoplastic liver, chronic non-suppurative cholangitis surrounded by epithelioid granuloma, resembling the granulomatous destructive cholangitis of primary biliary cirrhosis, was found. The damaged bile ducts were immunohistochemically minimally positive or ambiguous for HLA-DR, and their expression of the E2-subunit of the pyruvate dehydrogenase complex E2 (PDC-E2) was diffuse or granular, and not typical of primary biliary cirrhosis. There was no bile duct loss, and orcein-positive copper binding granules reflecting chronic cholestasis were negative in periportal hepatocytes. The overall features in this case were consistent with primary biliary cirrhosis presenting an infrequent profile of antimitochondrial antibodies and atypical expression of HLA-DR and PDC-E2 on biliary epithelial cells, with late superimposition on chronic hepatitis C. However, it is also possible that this is a case of chronic hepatitis C with hepatitis-associated bile duct damage accompanied by granulomatous reaction. Either way, this case raises new diagnostic issues in the differential diagnosis of chronic liver diseases presented with granulomatous cholangitis.

Autoimmunity in hepatitis C and D virus infection

A large number of viruses are capable of inducing acute or chronic hepatitis. The syndrome of chronic hepatitis encompasses not only viral but also autoimmune liver diseases. The hepatitis C virus, and recently also the hepatitis D virus have been found to be associated with an array of autoimmune syndromes, diseases and markers of autoimmunity. The relationship of hepatotropic virus infection and the immune system leading to virus-associated autoimmunity, and its distinction from genuine autoimmune disease represents a fascinating field of research. Clinically, the differentiation between autoimmune liver diseases, virus infection and virus-associated autoimmunity is difficult and epidemiological evaluations have not come up with universally applicable and valid classification criteria. However, both autoimmune liver diseases and viral hepatitis can readily be diagnosed and distinguished through precise and molecularly determined immunological testing systems. The overlap of both, virus-associated autoimmunity, is still at the centre of research activities aimed at establishing diagnostic and risk-assessment criteria. Studies of molecular autoantigens and autoepitopes have begun to define the differences of the B-cell response in autoimmune disease and virus-associated autoimmunity. This provides data that may contribute to the safe application of therapeutic strategies as different as immunosuppression and interferon-alpha (IFN-alpha). The present review focuses on the clinical, epidemiological and molecular aspects of these disease entities.

Autoimmune hepatitis versus viral hepatitis C

Numerous viruses are capable of inducing the syndrome of chronic hepatitis. Among them are the hepatitis B, C and D viruses. Out of the most common agents of chronic hepatitis, the hepatitis C virus has been found to be strikingly associated with autoimmune diseases and serological markers of autoimmunity. Conversely, the syndrome of genuine autoimmune hepatitis lacks evidence of previous or ongoing virus infection and is diagnosed by additionally excluding metabolic, toxic, and genetic causes of chronic hepatitis, and by the response to immunosuppressive treatment. This review article summarizes the current knowledge of hepatotropic virus-induced autoimmunity. It focuses on the present molecular and immunological definitions, the clinical and molecular distinction between autoimmune hepatitis and chronic viral hepatitis and the implications for the safe and efficacious therapy of these disease entities.