Mucosal nerves in endobronchial biopsies in asthma and non-asthma

To investigate neural events within the airways in asthma, endobronchial biopsies were obtained by fibre-optic bronchoscopy from 8 atopic asthmatic subjects and 8 non-atopic healthy controls. The biopsies were immediately fixed on sampling and subsequently analysed for nerves using specific indirect immunofluorescence with antisera to the neural marker PGP 9.5 and to the neuropeptides vasoactive intestinal peptide (VIP), substance P (SP) and calcitonin gene-related peptide (CGRP). Nerves were present in all the biopsies from both subject groups, with no significant difference between the asthmatic and non-asthmatics. VIP-immunoreactive nerves were equally present in both subject groups, being localized to smooth muscle and glandular sites. No immunoreactive nerves to SP or CGRP could be identified in any biopsy at any location. These in vivo findings do not identify an anatomical neuronal imbalance in asthma.