Neurotrophins have a functional role on eosinophils in atopic dermatitis

Abstract

Rationale Neurotrophins not only have a functional role on nerves but also on immunocompetent cells. Recently, the pivotal role of neurotrophins on eosinophils of patients with allergic asthma has been described. The aim of this study was to investigate the possible role of BDNF, NT-3 and NGF on peripheral blood eosinophils in atopic dermatitis (AD). Methods AD patients were defined according to the criteria of Hanifin and Rajika. Peripheral blood eosinophils were purified by CD16 negative selection (purity >98%) and stimulated with BDNF, NT-3 (10, 50, 100ng/ml), or NGF (100, 500, 1000ng/ml) for 24 up to 120 hours. Apoptotic eosinophils were investigated by determining their hypodiploid DNA peak and Annexin V method. Chemotactic index was assessed in a modified Boyden chamber assay and respiratory burst by lucigenin-dependent chemiluminescence. Results Stimulation with BDNF, NT-3 and NGF significantly inhibited the programmed cell death of AD eosinophils (p<0.05-0.01) at each time point (24 hours up to 120 hours in culture). Chemotactic index was significantly increased in AD eosinophils after stimulation with BDNF and NT-3 (p<0.05-0.01). Respiratory burst of AD eosinophils was not modified after stimulation with BDNF, NT-3 or NGF. Conclusions BDNF, NT-3 and NGF significantly inhibited the programmed cell death of AD eosinophils. However, BDNF, NT-3 and NGF did not modulate respiratory burst of AD peripheral blood eosinophils. On the other hand, BDNF and NT3 significantly induced AD eosinophil chemotaxis. Taken together, neurotrophins, such as BDNF, NT-3 and NGF have a functional role on peripheral blood eosinophils revealing neuro-immunological interactions in AD.