Background: The aim was to evaluate the association of plasma 25-hydroxyvitamin D (25-OHD) and vitamin D binding protein (VDBP or Gc-globin) gene polymorphism with oxidant-antioxidant profiles in patients with chronic obstructive pulmonary disease (COPD), and their role as biomarker risk factors in susceptibility and severity of COPD. Methods: Eighty patients diagnosed with COPD (mild, moderate and severe according to lung function tests; FEV 1%) and 80 healthy controls were included in the study. Serum nitric oxide (NO) and lipid peroxide (LP), plasma reduced glutathione (RGSH), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) activity, 25-OHD and VDBP polymorphism were analyzed in all subjects. Results: COPD patients had significantly decreased serum NO, plasma SOD, RGSH, GSH-Px, CAT and 25-OHD versus controls, but had significantly increased serum LP. In COPD patients, 25-OHD levels were significantly lower (41.49± 13.65 ng/mL) versus controls, but more lower in severe COPD patients (30.54±9.09 ng/mL; sensitivity 79.2%; spe - cificity 73.2%, p<0.001) versus mild and moderate COPD. VDBP genotypes frequencies were Gc1S-1S=23.8%, Gc1F-1S=28.8%, Gc1F-1F=15%, Gc1S-2=20%, Gc1F-2=11.3% and Gc2-2=1.3%. Also, VDBP variants frequencies were Gc1S=48.1%, Gc1F=35% and Gc2=16.6%. How ever, Gc1F-1S genotypes and Gc1F variants were significantly higher than in controls (10%, 12.5%; p=0.009, p=0.001, respectively). Moreover, in severe COPD patients, Gc1F-1S genotype was significantly higher than in mild COPD (41.7% vs 31.3%, p=0.04). Conclusion: COPD patients had significantly lower plasma 25-OHD and were associated with significantly higher VDBP Gc1F-1S genotypes and Gc1F variants frequencies than controls. Low vitamin D levels and VDBP polymorphism may be important as diagnostic risk factors in the susceptibility to and severity of COPD.
