[A review on thyroid autoimmune disorders and HCV chronic infection]

Frequently, patients with hepatitis C virus (HCV) chronic infection have high levels of serum anti-thyroperoxidase and/or anti-thyroglobulin autoantibodies, ultrasonographical signs of chronic autoimmune thyroiditis, and subclinical hypothyroidism, in female gender, vs healthy controls, or hepatitis B virus infected patients. In patients with "HCV-associated mixed cryoglobulinemia" (MC+HCV), a higher prevalence of autoimmune thyroid disorders was shown not only compared to controls, but also compared to HCV patients without cryoglobulinemia. Patients with MC+HCV or with HCV chronic infection, show an higher prevalence of papillary thyroid cancer than in 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 than patients without thyroiditis. Probably, HCV thyroid infection acts by upregulating CXCL10 gene expression and secretion in thyrocytes recruiting Th1 lymphocytes, that secrete interferon-gamma and tumor necrosis factor-alpha. These cytokines might induce a further CXCL10 secretion by thyrocytes, thus perpetuating the immune cascade, that may lead into the appearance of autoimmune thyroid disorders in genetically predisposed subjects. A careful monitoring of thyroid function and nodules are recommanded in HCV patients.