Association of IL-6 gene polymorphisms and COPD in a Spanish Population

Interleukin-6 (IL-6) is a potential mediator of systemic effects of Chronic Obstructive Pulmonary Disease (COPD). In the present case-control study we investigated the association of promoter polymorphisms of this gene and COPD in a cohort of 191 patients, smokers without COPD (n = 75) and a healthy control. population (n = 296). Besides spirometry, exercise capacity (6MWD, 6 min walking distance) and body mass index (BMI) were measured in COPD patients. Genotyping of the IL-6 polymorphisms at positions -174, -572 and -597 was performed. The -597G/A and -174G/C polymorphisms were not associated with the disease. However, the -572G/C polymorphism was significantly associated with COPD susceptibility under a dominant model. of inheritance. The frequency of the genotypes containing the C allele was significantly tower in the COPD cases (9.9%) compared with the healthy control group (16.9%) and smokers (23.1%), (OR = 0.46, p = 0.032 and OR = 0.28, p = 0.012, respectively). The GCG (-597/-572/-174) haplotype was significantly associated with the disease (OR = 0.37, p = 0.022, COPD cases vs. healthy subjects and OR = 0.17, p = 0.011, COPD cases vs. smokers). Moreover, a borderline association was also found for the -572G allele and hypoxemia (PaO(2) < 60 mmHg) (p = 0.05). Our data suggest that the IL-6 -572C allele may confer a diminished risk of developing COPD. (C) 2008 Elsevier Ltd. All rights reserved.