Airway sensory nerves: a burning issue in asthma?

Asthmatic subjects cough and bronchoconstrict to various agents known to stimulate sensory nerves. A population of sensory nerves, the C fibres, contain the neuropeptides substance P, neurokinin A (NKA), and calcitonin gene-related peptide (CGRP). Capsaicin, the principal ingredient of hot peppers, selectively stimulates C fibre afferents resulting in the release of these proinflammatory peptides. An upregulation in the function of sensory nerves may lead to augmented afferent and efferent function which, in asthma, could contribute to bronchial hyper-responsiveness, inflammation, and remodelling of the airway wall. Drugs specifically designed to attenuate the function of airway sensory nerves may prove useful in the treatment of asthma.