Cytokine response to the 6-min walk test in individuals with different degrees of COPD

Physical exercise is a key part of rehabilitation programs in chronic obstructive pulmonary disease (COPD) patients, although it could modulates immune system responses by altering the cytokine profile of such individuals. Furthermore, the degree of severity of COPD could influence the inflammatory response induced by exercise. To evaluate the cytokine profile of individuals with different degrees of COPD in response to a 6-min walk test (6MWT).

Forty-one patients with COPD were classified according to the severity of the disease by Global Initiative for Chronic Obstructive Lung Disease method: moderate = 14 individuals; severe = 14 individuals; very severe = 13 individuals. Blood sample collection was performed in the subjects pre and post a 6MWT. Cytokine plasma levels were analyzed to determine the cytokine profile using a Cytometric Bead Array technique (Becton Dickinson, San Jose, CA, USA) assay in flow cytometry.

A significant difference was observed in the interleukin (IL)-6 levels after test between very severe and severe groups (P = 0.036). Also, lower levels of IL-4 were observed in the severe group compared with the very severe and the moderate groups in the pretest (P = 0.029; P = 0.003, respectively), and different values between the moderate and severe groups in the post-test (P = 0.044). A significant time pre-post effect was found in the IL-4 levels on the very severe group (P = 0.046).

After the 6MWT, a discrete inflammatory response was observed in COPD patients, independent of the degree of severity. The results concerning IL-4 and IL-6 levels can be indicative of an attempt to control inflammation after the 6MWT in COPD patients.