Study of Serum Level of Lipoxin A4 in Exercise-Induced Bronchoconstriction in Asthmatic Children

Abstract
Background: Asthma is a chronic lung disease character-ized by wheezy chest, resulting from allergic inflammation and hyperresponsivness of the bronchi to various stimuli. Exercise-induced broncho constriction is a common manifes-tation of asthma in children and adolescents, occurring in up to 90% of asthmatic children. Lipoxins are the first agents determined to be anti-inflammatory endogenous lipid mediators involved in the resolution of inflammation. Since there is defective lipoxin biosynthesis in patients with severe asthma, we hypothesized that Lipoxin A4 may be related to develop-ment of exercise induced bronchoconstriction.
Aim of Study: It was to measure serum level of lipoxin A4 before and after exercise to evaluate its role in exercise induced bronchoconstriction in asthmatic children.
Patients and Methods: The study was carried out on fifteen children with mild intermittent or mild persistant asthma with positive response to exercise challenge test and fifteen children with mild intermittent or mild persistant asthma with negative response to exercise challenge test who attended to the outpatient clinic of Chest and Allergic Diseases, Pediatric Department, Tanta University Hospital. Also it was carried on fifteen apparently healthy children with matched age and sex served as a control group. All studied children were subjected to full history taking, thorough clinical exam-ination, plain chest X-ray, pulmonary function tests (FEV 1and PEFR) by spirometer before and after exercise challenge test, eosinophilic count, serum Lipoxin A4 by ELISA before and immediately after exercise challenge test. Data was analyzed by using SPSS.
Results: There was significant more decrease in serum Lipoxin A4 after exercise in asthmatic children with exercise induced bronchoconstriction as compared to asthmatic children without exercise induced bronchoconstriction. Regarding pulmonary function tests (FEV 1 and PEFR), there was signif-icant more decrease in FEV 1 after exercise in asthmatic children with exercise induced bronchoconstriction as com-pared to asthmatic children without exercise induced bron-choconstriction but, there was no significant difference between the asthmatic children with exercise induced bronchoconstric-tion and asthmatic children without exercise induced bron-choconstriction regarding the decrease in PEFR after exercise. And there was no statistical significant difference between subject's sex, age, residence nor BMI.
Conclusion: There was inverse correlation between serum LXA4 levels and a reduction in FEV 1 after exercise in asth-matic children. The demonstration of lower levels of lipoxin A4 in association with exercise induced bronchoconstriction suggest that the development of exercise-induced bronchoc-onstriction in asthmatic children may be due to reduced endogenous lipoxin biosynthetic capability. This association not affected by ages and sex of patients.