TNF‐α‐, TNF‐β‐, IL‐6‐, and IL‐10‐promoter polymorphisms in patients with chronic obstructive pulmonary disease

Abstract

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. In the present case-control study, we investigated interleukin (IL)-promoter polymorphisms known to correlate with altered transcription levels of their gene products in patients with COPD. We analyzed tumor necrosis factor-alpha (TNF-alpha)-308, TNF-beta-intron1-252, IL-6-174, IL-10-819, and IL-10-1082 polymorphisms in 469 individuals using restriction fragment length polymorphism-based converted polymerase chain reaction. The study population consisted of 113 patients with COPD based on chronic bronchitis, divided into subgroups by severity (I degrees -III degrees ), 113 matched hospitalized individuals suffering from severe coronary heart disease without pulmonary disease (age-, sex-, and smoking-matched control group), and 243 healthy individuals (population control group). The matched analysis showed no significant differences in genotype distribution of all tested polymorphisms between the matched controls and the COPD patients. However, comparison with the population controls revealed significant differences in IL-10-1082 A/G genotype frequencies (P = 0.0247 for the whole COPD group, P = 0.009 for smokers only), with the genotypes carrying the G allele more common in the COPD cases [odds ratio (OR) = 1.66, 95% confidence interval (CI) 1.01-2.75; P = 0.046]. Interestingly, this shift toward more G alleles was even more pronounced in the matched control group (OR = 2.55, 95% CI 1.47-4.41; P = 0.0007), suggesting both presented groups share corresponding underlying mechanisms. The IL-10-1082_G allele is known to correlate with altered IL-10 levels. Therefore, it might be associated with altered or abnormal inflammatory response, a mechanism that could be postulated to be important in both chronic bronchitis and coronary heart disease.