Lack of Associations Between Several Polymorphisms in Cytokine Genes and the Risk of Chronic Obstructive Pulmonary Diseases in Taiwan

Cytokine-induced inflammation is the predominant underlying mechanism in chronic obstructive pulmonary disease (COPD). Genetic factors may play a pivotal role in the development of this disease. This study looked at the relationship between COPD and genetic polymorphisms in the genes encoding some of these cytokines in a Taiwanese population. The genetic polymorphisms examined in this study were tumor necrosis factor (TNF)-α(−308), TNF-α(+489), interleukin(IL)-1β(−31), interleukin-1 receptor antagonist (IL-1 RN), and IL-6(−174). In total, 30 patients with COPD, 64 subjects at risk of COPD and 115 controls were recruited to the study between 1999 and 2003. DNA was collected from these subjects and analyzed by polymerase chain reaction with sequence-specific primers and restriction enzyme fragment length polymorphism analysis. The frequencies of cytokine genotypes in COPD cases and controls, respectively, were as follows: for G/G in TNF-α(−308), 76.7% and 83.5%; for G/G in TNF-α(+ 489), 76.7% and 68.7%; for C/T in IL-1β(−31), 60.0% and 55.7%; for 4R/4R in IL-1 RN, 80.0% and 86.1%; and for G/G in IL-6(−174), 100.1% and 98.3%. There was no difference in the distribution of the frequencies of these genotypes and alleles between COPD cases and controls. Moreover, no association was found between these genetic polymorphisms in cytokines and COPD (regardless of COPD subtypes) with respect to cigarette smoking or pulmonary function tests. Despite this, smoking is still an important risk factor for developing COPD.