Dictionary of Allergies .. Axon reflex mechanism

Inhaled environmental irritants or various mediators released from airway inflammatory cells stimulate vagal afferent nerve endings in the airway epithelium. This may trigger not only a reflex increase in efferent cholinergic activity but also the antidromic release of neuropeptides SP, NK and CGRP via a "short-circuited" local reflex loop.

These neuropeptides, in turn, may cause airway smooth muscle contraction, mucus production, edema, and release of inflammatory and proinflammatory mediators from various inflammatory cells. Chronic disease may then result since heightened inflammation in the airways and damage to airway epithelium further enhance neuropeptide release. In addition, degradation of the released tachykinin neuropeptides may be slowed because of disruption of airway epithelial membranes to which the neutral endopeptidases are normally bound.

References

Barnes, P.J.: Asthma as an axon reflex, Lancet 1:242, 1986.