Thyroid involvement in patients with overt HCV-related mixed cryoglobulinaemia

Thyroid disorders in chronic hepatitis C virus infection

The prevalence of thyroid disorders has been evaluated in patients with hepatitis C virus (HCV) infection by many studies. From a review of the published controlled studies, it is possible to observe that: (1) most investigated patients with chronic HCV hepatitis, while a minority evaluated hepatitis C virus antibody (HCVAb)- seropositive patients (the two conditions are not comparable with regards to thyroidal repercussions, in fact, HCVAb-seropositive patients do not necessarily display changes of the immune system present in chronically infected HCV patients); and (2) some authors selected as internal control hepatitis B virus (HBV)-infected patients, while others selected apparently healthy controls or HCVAb-negative subjects. Pooling all data about HCV-positive patients (with chronic hepatitis or HCVAb positivity) and using as control the sum of healthy controls, HBV-infected patients and sera negative for HCVAb, a significant increase of the prevalence has been observed both for thyroid autoimmune disorders (odds ratio [OR] = 1.6; 95% confidence interval = [C]) 1.4-1.9) as well as for hypothyroidism (OR = 2.9; 95% CI = 2.0-4.1). The results of the epidemiologic studies showing an association between HCV infection and thyroid cancer need to be confirmed. The abovementioned evidences seem sufficient to suggest careful thyroid monitoring during the follow-up of patients with HCV infection.

Cryoglobulinemic vasculitis

PURPOSE OF REVIEW

Cryoglobulinemic vasculitis is an immune-complex-mediated systemic vasculitis involving small-medium-sized vessels. A causative role of hepatitis C virus in over 80% patients has been definitively established, with heterogeneous geographical distribution. This review focuses on recent etiopathogenetic, clinico-diagnostic, and therapeutical studies.

RECENT FINDINGS

Hepatitis C virus cannot be integrated into the host genome; it may exert a chronic stimulus to the immune system. The interaction between hepatitis C virus envelope protein E2 with B-cell CD 81 receptor may increase the frequency of VDJ rearrangement in antigen-reactive B lymphocytes. One consequence is the activation of various protooncogenes, including anti-apoptotic Bcl-2. The extended B-cell survival is responsible for autoantibody and immune-complex production, including mixed cryoglobulins; some malignancies, mainly B-cell lymphomas, may complicate cryoglobulinemic vasculitis. Environmental or viral/host genetic cofactors should be relevant in the pathogenesis of hepatitis C virus-related diseases. Cryoglobulinemic vasculitis may overlap with other diseases (systemic vasculitides, Sjögren's syndrome, autoimmune hepatitis, lymphoma), which should be carefully considered for a correct diagnosis and treatment. Cumulative survival of cryoglobulinemic vasculitis is significantly lower compared with the general population. Therapeutic strategies for cryoglobulinemic vasculitis include etiologic (antiviral), pathogenetic (cyclophosfamide, rituximab), or symptomatic (steroids, plasmapheresis) treatments, which should be tailored to the individual patient according to the severity/activity of clinical symptoms.

SUMMARY

Cryoglobulinemic vasculitis represents a crossroads among autoimmune and lymphoproliferative disorders; as hepatitis C virus infection is the major causative factor, cryoglobulinemic vasculitis is an important model for etiopathogenetic studies of virus-related diseases.

Extrahepatic manifestations in patients with chronic hepatitis C virus infection

PURPOSE OF REVIEW

Chronic hepatitis C virus infection often has autoimmune clinical and analytic features. This review analyzes recent data on the close association of chronic hepatitis C virus infection with autoimmune and lymphoproliferative processes.

RECENT FINDINGS

Hepatitis C virus infection has been associated with both organ-specific (thyroiditis, diabetes) and systemic autoimmune diseases. Experimental, virologic, and clinical evidence has demonstrated a close association between hepatitis C virus infection and Sjögren syndrome, with hepatitis C virus-associated Sjögren syndrome being indistinguishable in most cases from the primary form. With respect to rheumatoid arthritis, patients with hepatitis C virus-related polyarthritis and positive rheumatoid factor may fulfill the classification criteria for rheumatoid arthritis. Hepatitis C virus has also been associated with an atypical presentation of antiphospholipid syndrome, as well as with the development of sarcoidosis. A higher prevalence of hematologic processes in patients with hepatitis C virus infection has recently been reported, including cytopenias and lymphoproliferative disorders. Recent data are available on the use of new immunosuppressive and biologic agents (mainly mycophenolate mofetil, anti-tumor necrosis factor agents, and rituximab) in patients with hepatitis C virus infection and autoimmune or lymphoproliferative manifestations.

SUMMARY

There is increasing evidence of a close association of hepatitis C virus infection with autoimmune and hematologic processes. The sialotropism of hepatitis C virus may explain the close association with Sjögren syndrome, and its lymphotropism links the virus to cryoglobulinemia, autoimmune cytopenias, and lymphoma. The substantial overlap between cryoglobulinemic features and the classification criteria for some systemic autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, and polyarteritis nodosa) make the differentiation between mimicking and coexistence difficult.