Abstract
Frequently, patients with hepatitis C virus (HCV) chronic infection have high levels of serum anti-thyroperoxidase and/or anti-thyroglobulin autoantibodies, ultrasonographic signs of chronic autoimmune thyroiditis, and subclinical hypothyroidism, in female gender versus healthy controls, or hepatitis B virus infected patients. In patients with “HCV-associated mixed cryoglobulinemia” (MC + HCV), a higher prevalence of thyroid autoimmune disorders was shown not only compared to controls, but also versus HCV patients without cryoglobulinemia. Patients with MC + HCV or HCV chronic infection show a higher prevalence of papillary thyroid cancer than controls, in particular in patients with autoimmune thyroiditis. Patients with HCV chronic infection, or with MC + HCV, in presence of autoimmune thyroiditis, show higher serum levels of T-helper (Th)1 (C-X-C motif) ligand 10 (CXCL10) chemokine, but normal levels of Th2 (C-C motif) ligand 2 chemokine, than patients without thyroiditis. HCV thyroid infection could act by upregulating CXCL10 gene expression and secretion in thyrocytes recruiting Th1 lymphocytes that secrete interferon-γ and tumor necrosis factor-α. These cytokines might induce a further CXCL10 secretion by thyrocytes, thus perpetuating the immune cascade, which may lead to the appearance of autoimmune thyroid disorders in genetically predisposed subjects. A careful monitoring of thyroid function, particularly where nodules occur, is recommended in HCV patients.
Highlights
About 130–170 million people worldwide have been infected by hepatitis C virus (HCV) [1]
Duclos-Vallee et al evaluated the prevalence of HCV infection in 200 patients with thyroid diseases; among 50 patients with simple goiter, none were anti-HCV-positive; among 50 individuals with goiter, 2 were positive; among 5 individuals with myxedema, 2 were positive; among 50 patients with Hashimoto’s thyroiditis, 12 were positive. These results suggested that HCV infection might be associated with autoimmune chronic thyroiditis (AT) [36]
The results of this study suggested that both hypothyroidism and thyroid autoimmunity are more common in patients with CHC, even in the absence of cirrhosis, hepatocellular carcinoma, or interferon treatment, than in HCV-negative controls or in patients with chronic hepatitis B infection [41]
Summary
About 130–170 million people worldwide have been infected by hepatitis C virus (HCV) [1]. An important feature of HCV is that the virus avoids immune elimination; a consequence is chronic infection and an accumulation of circulating immunocomplexes and autoimmune phenomena [6,7,8], as recently Cheng et al have demonstrated in their study among 297 Chinese patients [9] These EHM mainly include autoimmune disorders [10,11,12] such as MC [13, 14] and Sjogren’s syndrome and endocrinological diseases as autoimmune thyroid disorders (AITD) and type 2 diabetes [15,16,17]
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