title: Neuropeptides modulate human eosinophil chemotaxis.
abstract: To investigate the role of neuropeptides in allergic inflammation, we examined the effect of peptides on eosinophil chemotaxis. Eosinophils were purified from the blood of allergic and normal subjects using a discontinuous Percoll density gradients. Chemotaxis was induced by platelet-activating factor (PAF) and leukotriene B4, and was assayed by a modified Boyden's chamber technique. Four neuropeptides were examined in this study: substance P (SP), neurokinin A, calcitonin gene-related peptide (CGRP), and cholecystokinin octapeptide. Peptides alone (10 nM to 10 microM) were not chemotactic for eosinophils. However, when eosinophils were pre-treated with peptides (100 nM) at 37 degrees C for 30 min, chemotactic response to PAF (10 nM) was significantly enhanced (p < 0.01) in allergic subjects; % control by SP, neurokinin A, CGRP and cholecystokinin octapeptide was 269 +/- 42, 243 +/- 32, 227 +/- 21, and 251 +/- 42, respectively (n = 8). Similar results were obtained in leukotriene B4-induced eosinophil chemotaxis. In contrast, no enhancement was observed in normal subjects. Potentiating effect of SP and CGRP on PAF-induced eosinophil chemotaxis in allergic subjects was significantly attenuated by SP antagonist [D-Pro2,D-Trp7,9]-SP and human CGRP (8-37) receptor antagonist, respectively. Neutral endopeptidase inhibitors (phosphoramidon, leupeptin, and bestatin) failed to significantly augment the PAF-induced eosinophil chemotaxis when the cells were pretreated with various peptides and neutral endopeptidase inhibitors. The C-terminal fragment of SP (SP6-11) had an effect similar to that of the intact SP molecule, whereas no potentiating effect by the N-terminal of SP (SP1-9) was observed. These results suggest that neuropeptides may play a significant role in eosinophil infiltration by priming cells in allergic inflammation.
authors.affiliation: Allergic Disease Center, Creighton University School of Medicine, Omaha, NE 68178.
authors.forename: T
authors.initials: T
authors.lastname: Numao
authors.forename: D K
authors.initials: DK
authors.lastname: Agrawal
mesh_terms: D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004804:Eosinophils / Q000187:drug effects* / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology; D066298:In Vitro Techniques; D007975:Leukotriene B4 / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D010972:Platelet Activating Factor / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D018003:Receptors, Calcitonin; D011956:Receptors, Cell Surface / Q000187:drug effects; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter / Q000187:drug effects; D013373:Substance P / Q000494:pharmacology
chemical_list: D009479:Neuropeptides; D010446:Peptide Fragments; D010972:Platelet Activating Factor; D011480:Protease Inhibitors; D018003:Receptors, Calcitonin; D011956:Receptors, Cell Surface; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter; D007975:Leukotriene B4; D013373:Substance P