Brain-derived neurotrophic factor in asthmatic children

Abstract

Background: Brain-derived neurotrophic factor (BDNF) regulates the cross-talk between the immune and nervous systems which may play an important role in asthma pathophysiology. Objective: This study was aimed to investigate the relation between BDNF and asthma exacerbation and severity, and to study its possible correlation to eosinophilic counts in blood and sputum. Methods: Twenty-seven asthmatic children were studied during both exacerbation and remission. According to acute exacerbation severity as assessed clinically and by peak expiratory flow rate (PEFR), they were equally subdivided into 3 groups (mild, moderate and severe). Serum and sputum BDNF levels as well as blood and sputum eosinophilic counts were estimated in all patients in comparison to 30 healthy children with no personal or family history of atopy. Results: BDNF levels (in serum and sputum) and eosinophilic counts (in blood and sputum) were significantly elevated in asthmatic patients, whether studied as one group or subgrouped into mild, moderate and severe as compared to controls. Patients with mild, moderate and severe acute asthma exacerbation had significantly higher values of BDNF (in serum and sputum) and eosinophilic count (in blood and sputum) than the corresponding values measured during remission. The latter values were still higher than those of the control group. BDNF in serum and sputum indirectly correlated with asthma severity as evidenced by their negative correlation with PEFR. However, sputum BDNF correlated better with the severity of asthma exacerbation as evidenced directly by its significant increase with clinical severity. Both serum and sputum BDNF levels revealed significant positive correlations with eosinophilic count in blood and sputum among all studied groups. Conclusion: BDNF probably plays a role in the evolution of asthma exacerbation and it reflects the degree of asthma severity during exacerbation. It might also represent an objective indicator of remission and treatment efficacy. Studies with specific BDNF receptor antagonists or synthesis inhibitors are required as BDNF may prove to be a reasonable target for a new therapy in future.

Keywords: BDNF, neurotrophins, bronchial asthma, asthma severity, neurogenic inflammation

Egypt J Pediatr Allergy Immunol 2003; 1(2): 102-9