Comparison of immune cells and il-6 variations observed before and after exercise-induced bronchospasm in elite endurance athletes

Background: Exercise-induced bronchospasm (EIB) is a constriction of the bronchi that occurs in response to dehydration of the airways. EIB is characterized by a very common inflammatory condition in athletes. Therefore, the present study aims to assess the variations in circulating inflammatory cells and interleukin-6 (IL-6) levels before and after EIB in a population of endurance athletes. Materials and Methods: The study involved 16 athletes (23.56 ± 3.55 years, 171.62 ± 6.81 cm and 60.68 ± 5.53 kg). To determine the prevalence of EIB, the subjects were subjected to a laboratory stress test that consisted of a continuous treadmill run from 7.5 Km.h-1 with an increment of 1.5 Km .h-1 every 3 minutes until exhaustion. Respiratory functional explorations were carried out before and at 5 minutes after the effort using a Spirobank G spirometer. Blood samples were taken before exercise, immediately after exercise and at 2 hours after exercise, and EIB diagnosis was based on a reduction in blood pressure of at least 10% of the first-second forced expiratory volume (FEV1) in relation to the pre-exercise value. Subjects who presented this criterion were determined as sensitive to bronchospasm and formed the EIB (+) group. Subjects who were not identified as such were considered non susceptible and formed the EIB (-) group. Inflammatory cell counts were performed using an Elite3 automated system, and IL-6 plasma concentrations were determined using an IL-6 ELISA kit. Results: The prevalence of EIB was 37.5%. A significant mean decrease in the post exercise FEV1 of 16.31% was observed in the EIB (+) group compared with that in the EIB (-) group, confirming EIB in these individuals. For leukocytes and lymphocytes, the mean values were recorded immediately after exertion, and those obtained before exertion showed no significant difference (p > 0.05) in EIB (+) athletes, whereas in EIB (-) athletes, the mean values of leukocytes and lymphocytes observed immediately after exertion were significantly higher (p < 0.05) than those recorded before exercise. In the EIB (+) group, the mean concentrations of total granulocytes, neutrophils, eosinophils, basophils and IL-6 observed immediately after exertion were increased significantly (p < 0.05) compared to those measured before the effort . The mean leukocyte values recorded at 2 hours after exercise were significantly higher than those obtained before exercise in EIB (+) athletes. In the EIB (+) group, the mean value of the lymphocytes observed at 2 hours after exercise and the value recorded before exercise did not show a significant difference (p > 0.05), while in the EIB (-) group, the average value of lymphocytes obtained at 2 hours after exertion was significantly lower than the value recorded before exercise. The mean concentrations of total granulocytes, neutrophils, eosinophils, and basophils observed at 2 hours after exercise were significantly increased (p < 0.05) compared with those obtained before exercise in EIB (+) athletes. Conclusion: The occurrence of exercise-induced bronchospasm mobilizes a significant increase in inflammatory cells and IL-6 levels. Therefore, the immune system of athletes sensitive to EIB is strongly solicited.