Association of cytokine gene polymorphisms in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major health problem. The disease is driven by abnormal inflammatory reactions in response to inhaled particles and fumes. Therefore, inflammatory mediators are postulated to be of distinct importance. Keeping in view of the above facts; we investigate the role of polymorphisms of cytokine genes in the genetic predisposition of COPD.

In this present case-control study, the allele and genotype distributions of IL1B, IL1RN, TNF-α, and IL4 were studied in COPD patients (N=204) and healthy individuals (N=208). Genomic DNA was obtained by whole blood and genotyping was carried out by a polymerase chain reaction (PCR) based Restriction Fragment Length Polymorphism technique.

Genotype IL1RN*2/IL1RN*2 was identified as protective for male COPD, its frequency being 8.7% in COPD patients and 14.6% in healthy subjects (p=0.017; OR=0.53), but IL1RN*1/IL1RN*2 turned out to be a risk factor for females COPD. No significant differences were found between the groups of COPD patients and healthy subjects concerning the genotype frequencies of the polymorphisms T (-511) C of IL1B and 70bp VNTR of IL-4. Genotype GA of the TNF-α polymorphism G (-308) A was more common in the COPD patients than in the controls (20.5% vs.14.4%; p=0.107), and allele A was significantly associated with COPD patients (p=0.023; OR=0.65).

IL-1RN *2 allele appears to be significantly associated with the COPD female patients and TNF-α-308A allele is a risk factor for the development of COPD.