Serum interleukin-22 levels in monitoring the effect of treatment with dual bronchodilation in patients with COPD: should it be considered?

<bold>Background:</bold> Patients with chronic obstructive pulmonary disease (COPD) have higher serum interleukin-22 (IL-22) levels than nonsmoking controls. <bold>Aims and objectives:</bold> To evaluate the relation between pulmonary function tests and serum IL-22 and the changes in serum IL-22 levels during the 12 week treatment with dual bronchodilation in patients with newly diagnosed moderate-to-severe COPD. <bold>Methods:</bold> We studied 19 subjects of 40-76 years old with newly diagnosed moderate-to-severe COPD. Spirometry, gas diffusion and serum IL-22 ELISA were performed at baseline and after 12 weeks of dual bronchodilation. <bold>Results:</bold> Moderate COPD was dominant over severe (n=13 vs n=6). Median forced expiratory volume in 1 second % of predicted (FEV1%) was 53 (IQR 20). Reduced haemoglobin-corrected diffusing capacity for carbon monoxide % of predicted (DLCOc%) was observed in 7 subjects, 2 were borderline. Median DLCOc% was 78 (IQR 23). Majority of patients (n=15) had lung emphysema. Negative correlations between serum IL-22 and FEV1% (p=0.030; r=-0.498) as well as DLCOc% (p=0.006; r=-0.609) at baseline were observed. After 12 weeks of dual bronchodilation FEV1% improved significantly (mean 62 (IQR 23); p<0.001) while DLCOc% did not differ from baseline (mean 78 (IQR 23); p=0.958). There was no significant change in serum IL-22 after 12 weeks of dual bronchodilation (median 151.18 (IQR 43.53); p=0.623). <bold>Conclusions:</bold> Serum IL-22 may be associated with impaired lung function and destruction of lung parenchyma in COPD patients. However, this biomarker showed no benefit in monitoring the inflammation during the short-term COPD treatment with dual bronchodilation.