[Affection of epidermal growth factor on VIP secretion and VIPR expression in airway epithelial cells]

In order to confirm the essential role of vasoactive intestinal peptide(VIP) on protection of local airway epithelium and investigate the modulation of the protective effect of VIP, secretion of VIP and expression of VIP receptor(VIPR) were studied in bronchial epithelial cells(BEC), and alveolar macrophages (AM). The radioimmunoassay was used for determining VIP secretion and the radio-ligand affinity analysis for VIPR expression. The effect of epidermal growth factor(EGF) was observed. The results showed that: 1. Both BEC and AM secreted VIP basically without remarkable stimulus, and some vesicles with electron-dense core which usually exist specifically in neuropeptide secreting cells were found in plasma of BEC; 2. In a dose-dependent manner, EGF promoted BEC to secrete VIP(r = 0.84, P < 0.05), and it was found that VIP secretion from AM was also elevated in EGF pretreated group(P < 0.05); 3. EGF exhibited a dose-dependent up-regulatory effect on the expression of VIPR in BEC(r = 0.95, P < 0.01). These results indicate that VIP may play an essential role in the protection at local airway by autocrine or paracrine, and the protective effect can be modulated by growth factors.