Systemic inflammation has been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD) systemic effects. However, most COPD patients do not suffer from persistent systemic inflammation even after exacerbations and exercise and scientific evidence has provided conflicting results. Our aim is to evaluate inflammatory gene expression at rest and at 1 and 24h after strenuous exercise in COPD patients and study the patient variables associated with inflammatory expression.
A cross-sectional study was conducted in COPD patients who were recruited on entry to a pulmonary rehabilitation (PR) program. Demographic, clinical and functional data were collected. Blood samples were collected and gene expression was analyzed by reverse transcriptase polymerase chain reaction for IFNg, IL1b, IL6, IL8, TNFa, TGFb1 and iNOS.
The study included 21 patients (15 men, 71.4%), mean age 66.1 years old (SD=8.27), mean FEV1 46.76% (SD 20.90%), 67% belonging to GOLD grade D, mean BODE index of 3.9, 90.5% with smoking history, mean BMI 25.81 (SD=4.87), median of 1.29 exacerbations in the previous year.
There was no statistical significant difference between inflammatory expression at rest and at 1h and 24h after the maximal exercise test for all tested genes.
We found an association between BMI and inflammatory expression at all the points of time checked, a slight inverse association occurs with low BMI for mRNA IL1b, IL6, TNFa, TGFb1 and iNOS, and there was a more pronounced positive association for obese patients for all tested genes.
This preliminary study did not show an enhanced inflammatory gene expression from rest to 1h and 24h after short-term exercise, but did show an increased inflammatory gene expression in both BMI extremes, both at rest and after exercise, suggesting not only malnourishment, but also obesity as potential links between COPD and systemic inflammation. Studies with larger samples and designed to definitely exclude OSA or OHS as confounding factors in obese patients are required.