Lymphotropic virus infection of peripheral blood mononuclear cells in B-cell non-Hodgkin's lymphoma

Treatment of early stage chronic hepatitis C virus infection

INTRODUCTION

Treatment of Hepatitis C Virus (HCV) with direct acting antivirals (DAAs) is able to achieve the cure of infection in almost the totality of patients, independently of the characteristics of the individual and the virus, using short treatment schedules, and without the need of ribavirin. The high cost of DAAs is the main limiting factor for universal treatment of HCV. However, there is a strong evidence that treatment of infection at the early stage of disease may be the most rewarding approach. Areas covered: This review evaluates the aspects underlying the benefit of treating chronic HCV infection at the early stage of disease. It outlines the considerations that have to be taken into account when planning treatment in patients with HCV and minimal liver disease, assessing the positive reflex of viral eradication on several HCV-associated extra-hepatic conditions such as the risk of lymphoma, insulin-resistance and glycaemic control, and renal function. Lastly, it also covers the improvement of patients' quality of life and the pharmaco-economic aspects associated with early treatment. Expert commentary: Treatment of patients with HCV and minimal liver disease is associated with a beneficial, pleiotropic effect of viral eradication that goes beyond the simplistic consideration of the improvement in liver disease-related outcomes.

Pre-stimulation of CD81 expression by resting B cells increases proliferation following EBV infection, but the overexpression of CD81 induces the apoptosis of EBV-transformed B cells

Hepatitis C virus (HCV) E2 protein binds to CD81, which is a component of the B cell co-stimulatory complex. The E2-CD81 interaction leads to B cell proliferation, protein tyrosine phosphorylation and to the hypermutation of immunoglobulin genes. Epidemiological studies have reported a high prevalence of B cell non-Hodgkin lymphoma (NHL) in HCV-positive patients, suggesting a potential association between HCV and Epstein-Barr virus (EBV) in the genesis of B lymphocyte proliferative disorders. In the present study, in order to investigate the association between EBV and HCV in B cells, we created an in vitro EBV-induced B cell transformation model. CD81 was gradually overexpressed during transformation by EBV. B cells isolated from HCV-positive patients grew more rapidly and clumped together earlier than B cells isolated from healthy donors following EBV infection. Pre-stimulation of CD81 expressed by resting B cells with anti-CD81 monoclonal antibody (mAb) or HCV E2 accelerated the generation of lymphoblastoid cell lines (LCLs) by EBV infection. These cells proliferated prominently through the early expression of interleukin-10 and intracellular latent membrane protein (LMP)-l. By contrast, the overexpression of CD81 on EBV-transformed B cells by anti-CD81 mAb or HCV E2 protein induced apoptosis through reactive oxygen species (ROS)-mediated mitochondrial dysfunction. These results suggest that the engagement of CD81 expressed by B cells has differential effects on B cell fate (proliferation or apoptosis) according to EBV infection and the expression level of CD81.

Value of IL28B genotyping in patients with HCV-related mixed cryoglobulinemia: results of a large, prospective study

HCV-related mixed cryoglobulinemia (MC) is characterized by clonal expansion of B cells producing a polyreactive natural antibody (rheumatoid factor) and interferon (IFN)-based therapy is the first therapeutic option in mild-moderate MC. Single nucleotide polymorphisms (SNPs) proximal to genes involved in the innate response (IL28B/IFN-λ gene family) are strongly associated with spontaneous and IFN-induced viral clearance in hepatitis C, but no data exist about their role in HCV-positive MC. A large cohort of patients with HCV and MC was studied to evaluate the influence of IL28B genotype on the response to treatment and/or the evolution to MC of HCV infection. The rs12979860/rs8099917 IL28B polymorphisms were analysed in 481 consecutive HCV-positive subjects (250 with MC and 231 without MC, as controls) using real-time PCR and direct sequencing. Hundred and fifteen HCV patients with MC received standard anti-HCV therapy, and the results were evaluated according to the IL28B SNP distribution. Similar IL28B SNPs allele frequencies were recorded for patients and controls. IL28B major allele homozygosis (for both SNPs tested) was tightly correlated with virological and clinical response (P = 0.002). A statistically significant association was limited to 'difficult-to-treat' (G1/4) HCV genotypes. The IL28B genotype was a strong independent predictor of response (P = 0.007, OR 6.06; CI 1.65-22.22). The IL28B genotype was confirmed to be a useful predictor of response to IFN-based therapy in patients with HCV and MC. The very close correlation between IL28B SNP distribution, virological and clinical response definitively confirmed the key role played by HCV in MC. Conversely, the IL28B genotype does not seem to influence the evolution to MC.

Hepatitis C virus infection in the immunocompromised host: a complex scenario with variable clinical impact

The relationship between Hepatitis C Virus (HCV) infection and immunosuppression is complex and multifaceted. Although HCV-related hepatocytolysis is classically interpreted as secondary to the attack by cytotoxic T lymphocytes against infected cells, the liver disease is usually exacerbated and more rapidly evolutive in immunosuppressed patients. This generally occurs during the immunosuppression state, and not at the reconstitution of the host response after immunosuppressive therapy discontinuation. The field of immunosuppression and HCV infection is complicated both by the different outcome observed in different situations and/or by contrasting data obtained in the same conditions, with several still unanswered questions, such as the opportunity to modify treatment schedules in the setting of post-transplant follow-up. The complexity of this field is further complicated by the intrinsic tendency of HCV infection in itself to lead to disorders of the immune system. This review will briefly outline the current knowledge about the pathogenesis of both hepatic and extrahepatic HCV-related disorders and the principal available data concerning HCV infection in a condition of impairment of the immune system. Attention will be especially focused on some conditions - liver or kidney transplantation, the use of biologic drugs and cancer chemotherapy - for which more abundant and interesting data exist.

HCV and lymphoproliferation

Hepatitis C virus (HCV) infection is a serious public health problem because of its worldwide diffusion and sequelae. It is not only a hepatotropic but also a lymphotropic agent and is responsible not only for liver injury--potentially evolving to cirrhosis and hepatocellular carcinoma--but also for a series of sometimes severely disabling extrahepatic diseases and, in particular, B-cell lymphoproliferative disorders. These latter range from benign, but prelymphomatous conditions, like mixed cryoglobulinemia, to frank lymphomas. Analogously with Helicobacter pylori related lymphomagenesis, the study of the effects of viral eradication confirmed the etiopathogenetic role of HCV and showed it is an ideal model for better understanding of the molecular mechanisms involved. Concerning these latter, several hypotheses have been proposed over the past two decades which are not mutually exclusive. These hypotheses have variously emphasized the important role played by sustained stimulation of the immune system by HCV, infection of the lymphatic cells, viral proteins, chromosomal aberrations, cytokines, or microRNA molecules. In this paper we describe the main hypotheses that have been proposed with the corresponding principal supporting data.

Hepatitis C virus lymphotropism: lessons from a decade of studies

The possibility that HCV infects lymphoid cells has been widely discussed. Evidence in favor of HCV tropism for lymphoid cells derives from a series of data including: (1) the higher sensitivity of testing HCVRNA in PBMC than in serum or plasma samples, with possible detection of HCV RNA-positive PBMC in the absence of HCV viremia; (2) short-term cultures of PBMC which yield a significant increase in the amount of viral RNA on stimulation by mitogens; (3) results of "in situ" methods (i.e. in situ hybridization, immunofluorescence); (4) efficient infection of lymphoid cell lines or PBMC from normal individuals; (5) the persistence of HCV RNA in PBMC obtained from HCV-positive subjects and injected into SCID mice; (6) the long-term persistence of HCV RNA in PBMC in spite of HCV RNA negativity of serum and liver in sustained responder patients after therapy. The principal criticisms concerning effective HCV infection of lymphoid cells arise from technical difficulty in identifying HCV RNA replicative intermediate in these elements. Conflicting data may also result from differences in PBMC infection by different genotypes, samples taken at different stages in the disease process and differences in the sensitivity of detection methods, as well as low replication levels and/or proportion of infected PBMC. Interesting available data about HCV lymphotropism, which is possibly important in influencing the natural history of infection, include: (1) possible preferential viral tropism for specific PBMC subsets; (2) different lymphotropism of different viral strains; (3) selection of distinctive viral strains; (4) identification of putative HCV cell receptors; (5) association between determination of HCV lymphatic infection and t(14; 18) translocation. The clinical correlates of HCV lymphotropism are potentially very numerous, including, first, its role in determining HCV-related lymphoproliferative disorders.

Hepatitis C and D, retroviruses and autoimmune manifestations

Chronic infections with hepatitis C virus (HCV) are associated with various autoimmune manifestations, i.e. mixed cryoglobulinemia, membranoproliferative glomerulonephritis, autoimmune thyroid diseases, sporadic porphyria cutanea tarda and B cell lymphoma. Since exacerbation of hepatitis occurs in 5-10% of HCV patients receiving interferon-alpha treatment and may be successfully treated by immunosuppression afterwards, hepatitis C was also suspected to be associated with autoimmune hepatitis. LKM3 autoantibodies in chronic hepatitis D virus (HDV) infection and epitope recognition are discussed. Lately, endogenous and exogenous retroviruses have been investigated for the induction of autoimmune diseases. Human A type retroviral particles (HIAP), reverse transcriptase activity and anti-HIAP autoantibodies were detected in patients with Sjögren's syndrome. Anti-HIAP and anti-HIV p24 autoantibodies are seen in systemic lupus erythematosus, primary biliary cirrhosis and multiple sclerosis. Multiple sclerosis was even associated with a new human retrovirus called multiple sclerosis associated retrovirus (MSRV). In diabetes long terminal repeats (LTR) were detected in the HLA DQB1 locus, which was shown to associate with an increased risk of diabetes. A second retrovirus called IDDMK(1,2)22 was reported to code for a superantigen, which was implicated as a potential cause of diabetes. This hypothesis, however, was challenged repeatedly. Until now it is unknown whether endogenous retroviruses are aetiological agents of autoimmune diseases or an epiphenomenon, induced by coinfecting viruses (e.g. herpes viruses) and inflammatory processes.

Effects of immunosuppression and organ transplantation on the natural history and immunopathogenesis of hepatitis C virus infection

The hepatitis C virus (HCV) is recognized as the leading cause for parenterally transmitted hepatitis. It is characterized by a high propensity to chronicity. Several efforts have been directed towards understanding the natural history of chronic HCV infection and the immunopathogenic pathways involved in mediating liver injury in the non-immunosuppressed and immunosuppressed states. In the non-immunosuppressed setting, liver damage seems to be largely immune mediated. In contrast, in the non-immunosuppressed state, there are several other factors that may modify the natural course of the infection and play a role in mediating liver injury. In this review we will address the natural history, virological and immunological aspects of HCV infection. Also, the role played by immunosuppression and organ transplantation in modifying the course of the infection and the pathogenesis of liver injury will be discussed.

Mixed cryoglobulinaemia: a cross-road between autoimmune and lymphoproliferative disorders

Mixed cryoglobulinaemia (MC) is a systemic vasculitis, secondary to the deposition in small and medium-sized blood vessels of circulating immune complexes, mainly the cryoglobulins, and complement. MC is characterised by a typical clinical triad (purpura, weakness, arthralgias) and by one or more organ involvement: chronic hepatitis, glomerulonephritis, peripheral neuropathy, skin ulcers and diffuse vasculitis. In a limited number of MC patients, a malignancy, that is B-cell non-Hodgkin's lymphoma or hepatocellular carcinoma, may also develop. Hepatitis C virus (HCV) infection has been found in the majority of patients with MC; the frequency of HCV markers (91%) was significantly higher than other rheumatic diseases (6.4%), namely systemic lupus, Sjögren's syndrome, rheumatoid arthritis and systemic sclerosis, or healthy controls (1.2%). The HCV infection of lymphoid tissues may represent the remote event leading to B-lymphocyte proliferation responsible for autoantibodies and immune-complex production. In a similar way, HCV infection may also be involved in the pathogenesis of other autoimmune (glomerulonephritis, thyroiditis, lung fibrosis, autoimmune hepatitis, porphyria cutanea tarda) and lymphoproliferative disorders (monoclonal gammopathies, B-cell lymphomas). MC shares numerous clinico-serological and pathological features with the above disorders. HCV seems to be their common etiological agent; however, a variable combination of unknown co-factors (infectious, genetic, environmental) should be determinant for the appearance of different clinical patterns.