Extrahepatic Manifestations in Patients with Chronic Hepatitis C Virus Infection

Abstract

Autoimmunity and viral infections are closely related fields, and viruses have been proposed as possible etiologic or triggering agents of systemic autoimmune diseases (SAD). The hepatitis C virus (HCV), a linear, single-stranded RNA virus identified in 1989 (Choo et al., 1989), is recognized as one of the viruses most often associated with autoimmune features. A decade ago, various authors described the association of HCV infection with a heterogeneous group of extrahepatic conditions, such as pulmonary fibrosis, cutaneous vasculitis, glomerulonephritis, Mooren ulcers, porphyria cutanea tarda, or lichen planus (Gumber and Chopra, 1995), although it is currently accepted that a weak degree of association exists in some of them (Campisi et al., 2004). More recently, there has been growing interest in the relationship between HCV and SAD (Ramos-Casals et al., 2001a). The clinical association of the different SAD with chronic HCV infection may be analyzed from two different, but complementary, points of view. Firstly, a review of the literature found nearly 500 patients with coexisting SAD and chronic HCV infection (Ramos-Casals et al., 2005d), with Sjögren´s syndrome (SS; 182 cases), rheumatoid arthritis (RA; 94 cases), systemic lupus erythematosus (SLE; 67 cases), and polyarteritis nodosa (PAN; 41 cases) being the most frequent SAD described. Secondly, analysis of all references to series of patients with SAD tested for HCV shows the highest prevalences of HCV infection in patients with SS (17.6%), PAN (14.4%), SLE (9.6%), and RA (5.9%) (Ramos-Casals et al., 2005d). Other recent studies have focused on the association between chronic HCV infection and circulating autoantibodies, organ-specific autoimmune diseases, and lymphoproliferative processes.