Peripheral blood eosinophils priming and in vitro VEGF stimulation in asthmatics

Introduction
Asthma is a complex airway disease with heterogeneity in molecular pathways. Hypersecretion of many cytokines (e.g. vascular endothelial growth factor – VEGF), inflammatory cells infiltration (e.g. eosinophils) and different genetic factors (e.g. gene polymorphism) might be responsible for physiological and pathological changes in the course of this chronic disease.

Aim: To reveal the possible expression of activation marker CD69 on eosinophils unstimulated and stimulated by VEGF in patients with asthma. Additionally, the influence of a genetic factor (del18 genotype at -2549 -2567 position in the promoter of the VEGF gene) was considered.

Material and methods
The study involved 122 participants (82 patients with asthma and 40 healthy controls). CD69 expression on peripheral blood eosinophils was detected by flow cytometry without exogenous stimulation and after in vitro stimulation with VEGF. Genotyping for VEGF-promoter region was performed using the polymerase chain reaction method.

Results
CD69 was strongly presented (p < 0.05) on unstimulated eosinophils of patients with asthma and del18 genotype in the promoter of the VEGF gene. Stimulation of peripheral eosinophils with VEGF did not induce CD69 expression in a dose-dependent manner.

Conclusions
Our results may suggest the potential contribution of the VEGF gene polymorphism to the spontaneous increase of eosinophils activity (priming) in patients with asthma. In addition, the results show that VEGF is unlikely to significantly activate eosinophils in asthmatics.