Elevation of blood thioredoxin in hemodialysis patients with hepatitis C virus infection

BACKGROUND: Thioredoxin (TRX) is a stress-inducible thiol-containing protein, which has been shown to be an indicator of oxidative stress in a variety of diseases. The association between oxidative stress and hepatitis C virus (HCV) infection, however, remains unknown in hemodialysis patients. METHODS: We measured serum TRX levels in 85 hemodialysis patients positive for anti-HCV antibodies (age, 60 +/- 1 years old; hemodialysis duration, 17 +/- 1 years; M/F = 57/28) by enzyme-linked immunosorbent assay (ELISA), and examined whether blood TRX may be associated with HCV-related hepatic injury. RESULTS: Serum TRX was significantly higher in hemodialysis patients with HCV infection (112.3 +/- 3.7 ng/mL, N = 85) than in those without HCV infection (69.7 +/- 3.3 ng/mL, N = 59) (age, 69 +/- 2 years old; hemodialysis duration, 6 +/- 1 years; M/F = 32/27, P < 0.01) or normal subjects (28.0 +/- 5.4 ng/mL, N = 9). TRX was significantly correlated with time on hemodialysis (r = 0.27, P = 0.01) in HCV-positive patients, while it was associated with the patient's age in HCV-negative patients (r = 0.42, P < 0.01). Blood TRX was significantly correlated with asparate aminotransferase in patients with HCV infection (r = 0.34, P < 0.01) and without HCV infection (r = 0.46, P < 0.01). However, serum TRX was not associated with blood alanine aminotransferase, a relatively specific marker of hepatic cellular damage, in HCV-infected hemodialysis patients. A significant relationship was found between serum ferritin and TRX (r = 0.25, P = 0.02) and malondialdehyde (MDA) values (r = 0.25, P = 002) in HCV-positive patients. Serum TRX was also higher in the patients receiving weekly iron supplement with HCV infection (135.3 +/- 10.2 ng/mL vs. 110.2 +/- 3.9 ng/mL, P = 0.06) and without HCV infection (91.8 +/- 12.1 ng/mL vs. 65.2 +/- 2.7 ng/mL, P < 0.01). CONCLUSION: There was a greater increase in serum TRX in hemodialysis patients with HCV viremia than without HCV viremia. However, there may not be an association between serum TRX and HCV-related hepatic injury. TRX increased with serum ferritin in HCV-infected patients and further increased by iron infusion. These findings indicate that HCV infection and iron loading may aggravate oxidative stress in dialysis patients.