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.

Chronic neurokinin-1 receptor antagonism fails to ameliorate clinical signs, airway hyper-responsiveness or airway eosinophilia in an experimental model of feline asthma

“…Finally, the perpetuation of airway inflammation is dependent on multiple redundant pathways and it has been speculated that following the establishment of a persistent cell-mediated inflammatory response, blockade of tissue NK-1 receptors is insufficient to prevent further eosinophil influx and airway remodeling. 3,33,34…”

International consensus statement on allergy and rhinology: Allergic rhinitis – 2023

“…Elevated cysteine protease inhibitor cystatin SN was also observed with greater loss of sense of smell 250 . Neuropeptide mediated eosinophil chemotaxis, including substance P, CGRP, and cholecystokinin octapeptide, has also been described as a contributing factor to the symptomatology in NARES patients 251 …”