The association of HCV-infection with B-lymphomas is supported by the regression of most indolent/low-grade lymphomas following anti-viral therapy. Studies on direct and indirect oncogenic mechanisms have elucidated the pathogenesis of HCV-associated B-lymphoma subtypes. These include B-lymphocyte proliferation and sustained clonal expansion by HCV-envelope protein stimulation of B-cell receptors, and prolonged HCV-infected B-cell growth by overexpression of an anti-apoptotic BCL-2 oncogene caused by the increased frequency of t(14;18) chromosomal translocations in follicular lymphomas. HCV has been implicated in lymphomagenesis by a "hit-and-run" mechanism, inducing enhanced mutation rate in immunoglobulins and anti-oncogenes favoring immune escape, due to permanent genetic damage by double-strand DNA-breaks. More direct oncogenic mechanisms have been identified in cytokines and chemokines in relation to NS3 and Core expression, particularly in diffuse large B-cell lymphoma. By reviewing genetic alterations and disrupted signaling pathways, we intend to highlight how mutually non-contrasting mechanisms cooperate with environmental factors toward progression of HCV-lymphoma.

Hepatitis C virus (HCV) infection has been demonstrated to result in several adverse hepatic outcomes and has been associated with a number of important extrahepatic manifestations. The scope of extrahepatic clinical possibilities includes systemic diseases such as vasculitis and lymphoproliferative disorders, cardiovascular disease, myalgia, arthritis, and sicca syndrome. These end-organ effects of HCV may dominate the clinical course beyond the hepatic complications and significantly worsen the long-term prognosis of infected patients. Until several years ago, the standard of care for the treatment of HCV infection had been interferon-alpha-based regimens, which not only had limited effectiveness in achieving a cure but were often poorly tolerated, especially in patients with kidney disease. In those HCV-infected patients with significant systemic manifestations, the interferon-based regimens were problematic given their association with a wide variety of toxicities. The development of highly effective direct-acting antiviral agents to treat HCV infection presented an opportunity to improve the HCV care cascade with the eradication of HCV in most infected patients and by reducing the burden of both hepatic and extrahepatic complications.

During hepatitis C virus (HCV) chronic infection, extrahepatic manifestations are frequent and polymorphous. This article reports on a large cohort of patients with HCV-related autoimmune or lymphoproliferative disorders, from mixed cryoglobulinemia vasculitis to frank lymphomas. The relationship between HCV infection and such immune-related diseases has been formally demonstrated by epidemiological, clinical, immunological and pathological data, and results of therapeutic trials. More recently, other nonliver-related HCV disorders have been reported, including cardiovascular (i.e. stroke, ischemic heart disease), renal, metabolic and central nervous system diseases. For these manifestations, most evidence comes from large epidemiological studies; there is a need for mechanistic studies and therapeutic trials for confirmation. Beyond the risk of developing liver complications, that is, cirrhosis and liver cancer, patients with HCV infection have an increased risk of morbidity and mortality related to nonliver diseases. HCV chronic infection should be analyzed as a systemic disease in which extrahepatic consequences increase the weight of its pathological burden. The need for effective viral eradication measures is underlined.

HCV chronic infection is characterized by possible development of both hepatic and extrahepatic manifestations. The infection by this both hepatotropic and lymphotropic virus is responsible for polyoligoclonal B-lymphocyte expansion, leading to several immune-mediated disorders. Mixed cryoglobulinemia syndrome that in some cases may evolve to frank B-cell non-Hodgkin's lymphoma is the prototype of HCV-driven autoimmune and lymphoproliferative disorders. The HCV oncogenic potential has been suggested by several clinicoepidemiological and laboratory studies; it includes hepatocellular carcinoma, B-cell non-Hodgkin's lymphoma and papillary thyroid cancer. The definition HCV syndrome refers to the complex of HCV-driven diseases; these latter are characterized by heterogeneous geographical distribution, suggesting a role of other important genetic and/or environmental cofactors. The natural history of HCV syndrome is the result of a multifactorial and multistep pathogenetic process, which may evolve from mild manifestations to systemic autoimmune disorders, and less frequently to malignant neoplasias. The present updated review analyzes the clinical and pathogenetic aspects of the main HCV-associated diseases.

Limited data are available about the efficacy of antiviral treatment in hepatitis C virus (HCV)-associated mixed cryoglobulinemia (MC), especially concerning the long-term effects of HCV eradication. The aim of this study was to evaluate the influence of MC on the virological response and the long-term effects of viral eradication on MC. We prospectively enrolled 424 HCV(+) patients belonging to the following groups: MC syndrome (MCS)-HCV (121 patients with symptomatic MC), MC-HCV (132 patients with asymptomatic MC), and HCV (158 patients without MC). Pegylated interferon plus ribavirin treatment was administered according to standard protocols. Posttreatment follow-up ranged from 35 to 124 months (mean 92.5 months). A significant difference was observed in the rate of sustained virological response between the HCV group and both the MC-HCV (P = 0.009) and MC-HCV+MCS-HCV (P = 0.014) groups. Multivariate logistic regression analysis identified cryoglobulinemia as an independent prognostic factor of nonresponse. The clinical-immunological response in MCS-HCV correlated with the virological one. All patients with sustained virological response also experienced a sustained clinical response, either complete or partial. In the majority of sustained virological response patients all MCS symptoms persistently disappeared (36 patients, 57%); in only two (3%) did definite MCS persist. All virological nonresponders were also clinical nonresponders, in spite of a transient improvement in some cases. No evolution to lymphoma was observed. For the first time we have evaluated both the effects of interferon-based therapy on HCV patients with and without MC and with and without symptoms, as well as the long-term effects of viral eradication on MC.

MC is a negative prognostic factor of virological response. Clearance of HCV led to persistent resolution or improvement of MCS, strongly suggesting the need for a next generation of highly effective antiviral drugs.

Hepatitis C virus (HCV) infected patients are known to be at risk of developing liver complications i.e. cirrhosis and liver cancer. However, the risks of morbidity and mortality are underestimated because they do not take into account non-liver consequences of chronic hepatitis C virus infection. Numerous extrahepatic manifestations have been reported in up to 74% of patients, from perceived to disabling conditions. The majority of data concern hepatitis C virus-related autoimmune and/or lymphoproliferative disorders, from mixed cryoglobulinaemia vasculitis to frank lymphomas. More recently, other hepatitis C virus-associated disorders have been reported including cardiovascular, renal, metabolic, and central nervous system diseases. This review aims to outline most of the extrahepatic manifestations that are currently being investigated, including some of autoimmune and/or lymphoproliferative nature, and others in which the role of immune mechanisms appears less clear. Beyond the liver, hepatitis C virus chronic infection should be analyzed as a multifaceted systemic disease leading to heavy direct and indirect costs. The accurate consideration of extrahepatic consequences of such a systemic infection significantly increases the weight of its pathological burden. The need for effective viral eradication measures is underlined.

Hepatitis C virus (HCV) is a hepatotrophic and lymphotrophic virus and is a global health problem. Cirrhosis and hepatocellular cancer are the most common complications of HCV. Association between HCV and B cell non-Hodgkin lymphomas (B-NHL) has been shown in epidemiological studies in the last 20 years. High prevalence of HCV infection among patients with NHL has been reported in the early 1990s by Ferri in Italy and this association has been confirmed in later studies. Geographically, HCV related NHL is highly variable and chronic rather than cleared HCV infection is required for lymphomagenesis. Although anti-HCV antibody test is the most commonly used technique in epidemiological studies, HCV-RNA is more useful test to detect the association between HCV and NHL. The optimal management of HCV related NHL is not clear. However, anti-viral treatment may be sufficient for cases with low grade and/or asymptomatic lymphomas, while immuno-chemotherapy is necessary, in spite of probable hepatic toxicity, in cases with high grade lymphomas.

Hepatitis C Virus (HCV) is a major health problem, infecting about 3 % of people worldwide and leading to liver as well as extrahepatic diseases. This justifies the definition of HCV infection as a systemic disease. Based on available data, the link between the virus and some of these extrahepatic disorders is certain, whereas for some others needs further confirmation. HCV-related lymphoproliferative disorders, ranging from benign, but pre-lymphomatous conditions, like mixed cryoglobulinemia, to frank lymphomas, represent the extrahepatic manifestations most closely related to HCV. The primary involvement of the liver and lymphatic system corresponds to the double viral tropism, being HCV able to infect both hepatic and lymphatic cells. Other HCV-associated disorders include renal, endocrine, dermatological, cardiovascular, rheumatologic and central nervous system diseases. On the whole, the HCV disease appears a very important, mainly hidden, public health problem leading to heavy direct and indirect costs. The possibility that HCV may be eradicated following antiviral therapy is important for both the therapeutic and preventive points of view, making the HCV disease an ideal model for pathogenetic studies.

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 may cause hepatic and extrahepatic diseases. Extrahepatic manifestations range from disorders for which a significant association with viral infection is supported by epidemiologic and pathogenetic data, to anecdotal observations without clear proof of causality. This article describes the diagnosis and treatment of these diseases.

The aim of this study was to investigate the quasispecies heterogeneity of hepatitis C virus (HCV) in the plasma, cryoprecipitate, and peripheral lymphocytes of chronically infected HCV patients with mixed cryoglobulinemia (MC). We studied 360 clones from 10 HCV-positive patients with MC and 8 age-, gender- and HCV genotype-matched subjects with chronic HCV infection but without MC. A partial nucleotide sequence encompassing the E1/E2 region, including hypervariable region 1 (HVR1), was amplified and cloned from plasma, cryoprecipitates, and peripheral blood mononuclear cells (PBMC), and the genetic diversity and complexity and synonymous and nonsynonymous substitution rates were determined. Heterogeneous selection pressure at codon sites was evaluated. Compartmentalization was estimated by phylogenetic and phenetic (Mantel's test) approaches. The patients with MC had 3.3 times lower nonsynonymous substitution rates (1.7 versus 5.7 substitutions/100 sites). Among the subjects with HCV genotype 1, the MC patients had significantly less complexity than the controls, whereas the diversity and complexity were similar in the genotype 2 patients and controls. Site-specific selection analysis confirmed the low frequency of MC patients showing positive selection. There was a significant correlation between positive selection and the infecting HCV genotype. The quasispecies were less heterogeneous in PBMC than in plasma. Significant compartmentalization of HCV quasispecies was observed in the PBMC of four of nine subjects (three with MC) and seven of nine cryoprecipitates. In one subject with MC, we detected a 5-amino-acid insertion at codons 385 to 389 of HVR1. Our results suggest reduced quasispecies heterogeneity in MC patients that is related to a low selection pressure which is probably due to an impaired immune response, the HCV genotype, and/or the duration of the infection. The frequent HCV quasispecies compartmentalization in patients' PBMC suggests a possible pathogenetic significance.

In order to determine whether peripheral blood mononuclear cells (PBMC) contain proviral DNA or double-stranded replicative forms of TT virus (TTV) and to define which cell subset harbors TTV, we analyzed 126 PBMC DNA samples by PCR, using the NG059/NG061/NG063 and the T801/T935 primer sets. TTV sequences were detected in nearly 20% (25/126) of PBMC DNA samples. Analysis of PBMC subsets revealed that TTV was preferentially distributed in CD19(+) cells. TTV DNA was also detected in CD3(+)/CD19(+) double-depleted cells but was undetectable in CD3(+) cells. After degradation of single-stranded DNA using mung bean nuclease (MBN), TTV could not be detected in previously TTV-positive PBMC DNA samples nor in DNA from CD19(+) cells, CD3(+)-depleted, and CD3(+)/CD19(+) double-depleted cells, indicating the lack of TTV DNA integration and the absence of viral double-stranded replicative intermediates in PBMC or PBMC subset cells. Our data indicate that PBMC and PBMC subsets are not the major sites of TTV replication.

It is widely thought, but not yet explained, that there might be a pathogenetic link between the infection of hepatitis C virus (HCV) and the onset of B non-Hodgkin's lymphoma (NHL). We studied the prevalence of serum anti-HCV antibodies among 300 NHL comparing it with the prevalence among 600 age- and sex-matched non-neoplastic subjects as controls, 247 patients with non-lymphomatous neoplasm, and 122 patients treated with immunosuppressive agents. We found a prevalence of 0.16 among NHL and 0.085 among controls and non-lymphomatous patients. Although the difference was statistically significant (P < 0.001), the odds ratio was 2.049 and its confidence intervals included the equality. The HCV prevalence was independent of NHL subset, and the genotypes distribution was the same among NHL and controls. We disclosed a HBsAg prevalence of 0.077 in NHL versus 0.008 in controls (P < 0.001) with an odds ratio of 9.9. We do not believe that these findings support the hypothesis of an HCV pathogenetic role in lymphomagenesis because (i) the risk of previous infection is marginally higher in NHL than in controls, (ii) a typical genotype distribution is lacking, as is a NHL clinico-histological feature associated with HCV, and (iii) the higher prevalence of viral infection is not specific as witnessed by the high HBsAg prevalence.

Cryoglobulinemia may be found in a spectrum of disorders spanning clear-cut-B-cell neoplastic states, in which cryoprecipitation manifests as ischemic or occlusive vasculopathy, to a variety of immune complex diseases, in which vasculitis or glomerulonephritis may occur. Symptomatic cryoglobulinemia is many diseases, driven by and driving antibody-antigen responses, hepatic dysfunction, lymphoproliferation, and immune complexes. Distinguishing features that cause only some cryoglobulins to be symptomatic, elucidating the pathogenic mechanisms of HCV in cryoglobulin formation, and devising better therapies and more systematic evaluation of existing therapies are among the challenges for the future. Prognostication and classification will continue to rely on Brouet's classification (types I, II, and III), but additional features will probably include the presence or absence of HCV, HCV factors (genotype, titer), coexisting infections, B-cell clone burden, host factors, and immune system interactions (B- and T-cell idiotype networks, cytokines). Although antiviral therapy is a reasonable option for HCV-associated cryoglobulinemia, not all patients are HCV-positive, and only 60% to 80% of HCV-positive patients respond to IFN. In addition, not all patients tolerate IFN, and in those who do, the response is often short-lived once the treatment is discontinued. Only creative strategies, systematically studied, will provide long-awaited solutions.

Chronic viral infection has been implicated in the pathogenesis of B-cell lymphoma, and hepatitis C virus (HCV) infects lymphocytes. Chronic infection with HCV may result in B-cell proliferation. Individuals infected with hepatitis C are often co-infected with the RNA virus GB virus type C. Studies from Europe where hepatitis C infection is more common than in North America have shown a high prevalence of hepatitis C infection in patients with B-cell lymphoma. The aim of this study was to establish the prevalence of HCV and GBV-C infection in patients with B-cell lymphoma in an area of low HCV prevalence. One hundred patients with B-cell lymphoma (10 high grade, 46 intermediate grade, and 44 low grade) and 100 controls with nonhematological malignancies were studied. Serum was analyzed for HCV antibodies by third generation enzyme-linked immunosorbant assay, and HCV RNA and GBV-C RNA was analyzed by reverse transcriptase PCR. None of the controls or lymphoma patients had antibodies to HCV. HCV RNA was undetected in 60 out of 100 lymphoma patients tested. GBV-C RNA was detected in the serum of 5 out of 100 (5%) of lymphoma patients and in 3 out of 100 (3%) controls. Hepatitis C and GBV-C are, therefore, unlikely to play a major role in the pathogenesis of B-cell lymphoma in North America.

Hepatitis C virus (HCV) is a bloodborne agent transmitted by apparent and inapparent parenteral procedures representing a frequent cause of liver disease world-wide. Both acute and chronic HCV infection may affect the liver as well as various non-hepatic tissues. Numerous extrahepatic disorders have been recognised in association with HCV infection among which dermatological diseases occupy a central part. Cutaneous necrotising vasculitis, mixed cryoglobulinemia, porphyria cutanea tarda and lichen planus are the major skin diseases frequently associated with HCV infection, but other skin disorders, such as Adamantiadis-Behçet syndrome, erythema multiforme and nodosum, malacoplakia, urticaria and pruritus, may also be linked to hepatitis C. Further studies are necessary to establish or refute an aetiopathogenetic role of HCV in these conditions. Skin manifestations are also part of the clinical picture of other extrahepatic disorders associated with HCV infection, such as thyroid dysfunction and HCV-related thrombocytopenia. The response to interferon alpha (alpha-IFN) therapy in skin diseases is unpredictable with some patients ameliorating, others remaining stationary and others deteriorating.

Recent reports suggest that hepatitis C virus (HCV) might be a causative agent of mixed cryoglobulinemia. To determine whether the HCV genotype is a factor implicated in the onset of cryoglobulinemia, genotyping by direct sequencing of polymerase chain reaction products of the 5' non coding region was carried out among 45 HCV-infected patients. Genotypes 1 and 2 were found more prevalent in symptomatic cryoglobulinemia patients. Due to the presence of genotypes 4 and 5 found in this panel of French patients (9.3%), HCV genotyping based on sequence determination is recommended.

The strong association of HCV infection with MC-II and the selective concentration of the virus with the WA mRF in the cryoglobulins are compelling suggestions that the virus is directly involved in production of the mRF and the pathophysiology of MC-II. There is, however, only limited data on HCV involvement in both processes. In cutaneous vasculitis, which is the most prevalent clinical feature of the disease, there is evidence that complexes of HCV, mRF and IgG are formed in situ from components of the cryoglobulins that are present in the blood in a dissociated state. It is postulated that local factors, cooling and stasis predispose to formation of these lesions in the lower limbs. However, since cutaneous vasculitis does not correlate with cryoglobulin levels and may not be induced by cold challenge, other factors may be involved. In particular, the conditions which activate the vascular endothelial cells, leading to the leukocytoclastic vasculitis, require delineation. In contrast to cutaneous vasculitis, HCV RNA has not been prominently detected in immune complexes in MPGN lesions and has not been detected at all in the peripheral neuropathy lesions. These preliminary observations suggest that different pathophysiological processes are involved in for these lesions than in cutaneous vasculitis. From the correlation of remission of disease with decreased cryoglobulinemia and viremia in treated patients with MC-II, and from immunohistological data on the hepatitic lymphoid follicles in MC-II (see chapter 7), it appears that an antigen-driven benign proliferation of B cells is responsible for production off mRF and cryoglobulinemia. New findings have suggested that one mechanism for developing mixed cryoglobulinemia may be that HCV-VLDL complexes that contain apo E2 are poorly endocytosed by the LDLR, which may be a major route of entry of the virus to the cell; persistence of the complexes in the circulation may then stimulate mRF production. This new hypothesis is based only on initial in vitro observations and require independent confirmation and validation in vivo. From indirect clinical evidence it has also been postulated that mRF in some patients may limit the cytopathology in MC-II, resulting in a lower prevalence of cirrhosis in these patients. These findings suggested another hypothesis, which is that the mRF prevents spread of infection to hepatocytes and other permissive and nonpermissive cells by blocking endocytosis of HCV-VLDL complexes by the LDLR. Furthermore, data on the composition of cryoglobulins, the molecular composition of WA mRF and the characterization of monoclonal B cells in the liver of patients with MC-II (see chapter 7) suggest that a specific population of B cells may be involved in the host response to HCV infection. These are B cells that proliferate with little or no somatic mutations of the immunoglobulin genes, are self-replicating, are stimulated by self antigens in a T cell-independent manner and bear the CD5 marker. The proliferation of this B cell population may be the host's response to the attempt by the virus to circumvent the immune response by complexing with host lipoproteins. It is proposed that HCV complexed to VLDL is the antigen that directly stimulates the proliferation of these primordial type B cells. Testing of these hypotheses may produce insights not only into the etiology of mixed cryoglobulinemia but possibly into the mechanisms by which HCV circumvents the immune response and established chronic infection.

We have examined the clinical (virological and immunological), histological and immunohistochemical features of liver lymphoid nodules in hepatitis C virus-positive (HCV+)/mixed cryoglobulinemia (type II and III) and chronic hepatitis C. The clinical features of liver disease were found to be similar in all patients. In all these groups, liver lymphoid nodules were observed to a similar extent, being more frequent in earlier phases of liver disease and less in more advanced stages. These data were confirmed by studies in serial biopsy samples taken from individual patients with type II mixed cryoglobulinemia; the loss of lymphoid nodules with progression to more advanced histological stages of disease in these patients was accompanied by a decrease of the serum levels of cryoglobulins (although not statistically significant). By immunohistochemical analysis, the liver lymphoid nodules contained predominantly B cells with a CD5+/bcl2+/Ki67- phenotype, which were always polyclonal in type III mixed cryoglobulinemia and chronic hepatitis C, and monoclonal in type II mixed cryoglobulinemia. These immunological features were consistent with an active role of the immune system in HCV-associated liver necro-inflammation. Only in type II mixed cryoglobulinemia was there a clonal restriction of B cells. The immunological profile (autoantibodies) and viral genotypes were examined in some patients, but no significant correlation with clinical and immunohistochemical findings was found; however, the prevalence of genotype 2a was significantly higher in type II mixed cryoglobulinemia than in type III and chronic hepatitis without cryoglobulinemia.

The aim of this study was to characterize hepatitis C virus (HCV) infection in patients with mixed cryoglobulinaemia (MC). The HCV RNA copy number was assayed in clinical specimens from 15 consecutive patients with MC and HCV infection. Absolute quantification of HCV RNA molecules was performed using a competitive reverse transcription-polymerase chain reaction (cRT-PCR). Specific HCV RNA sequences were detected and quantified in plasma samples from all patients (mean HCV RNA copy number 4.9 x 10(6) ml-1 plasma). A high concentration of HCV RNA molecules was detected in the cryoprecipitates of eight of the 15 patients, who had a cryoprecipitate/supernatant ratio higher than 3.0 (range 3.60 to 186.80): in the remaining seven patients this ratio was close to or lower than 1.0 (range 0.13 to 1.60). Quantitative analysis of HCV RNA molecules in cells other than hepatocytes (i.e. peripheral blood mononuclear cells (PBMCs) and bone marrow cells (BMCs), in which the HCV replicative intermediate was detected using strand specific RT-PCR, demonstrated that infection is detectable in nearly 60% of these extrahepatic cells. Quantitative analysis of HCV RNA in PBMCs and BMCs revealed low levels of viral nucleic acids.