Serum neurotrophin-3 and neurotrophin-4 levels are associated with asthma severity in children.

In recent years, several studies have analysed the effects of neurotrophins on allergic inflammation and airway diseases. Elevated brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF) and neurotrophin-3 (NT-3) levels have been found in bronchoalveolar lavage fluid (BALF) after allergen challenge in allergic asthmatic patients [1, 2]. It has also been shown that asthmatic patients demonstrate elevated levels of neurotrophins (NGF and BDNF) in serum and locally in the airways [3, 4], and that allergen provocation significantly increases neurotrophin levels in the airways [2]. Increased neurotrophin (BDNF) concentration also correlated with clinical parameters of allergic airway dysfunction, such as airflow limitation and airway hyperresponsiveness, in asthmatic patients [5], whereas its level is normalised after treatment with inhaled corticosteroids [4]. However, to our knowledge, only one study has investigated neurotrophin (BDNF) levels in a paediatric population of asthmatic patients [6].