ABSTRACT
Neuroepithelial bodies (NEBs) are corpuscular arrangements of endocrine cells in the airway epithelium that are implicated in the regulation of lung organogenesis and that act as hypoxia-sensitive chemoreceptors. Their strategic position in contact with the inhaled air, in combination with their endocrine nature, might also enable them to detect intraluminal antigens and to modulate the local immune response by secretion of specific immunomodulatory substances. In this paper, some ultrastructural aspects of the secretory response of NEBs to ovalbumin (OVA) were quantified in a mouse model of allergic asthma. Mice were sensitized to OVA and challenged with OVA or saline. Sensitization, alone or followed by OVA challenge, increased the number of exocytotic profiles and the volume percent of dense-cored vesicles (DCVs), indicating enhanced secretion as well as synthesis of bioactive substances. Therefore, NEBs appear to respond to systemic sensitization with synthesis and subepithelial secretion of messenger molecules, suggesting a role in airway homeostasis and allergic airway disease. A prime candidate immunomodulatory messenger molecule among several bioactive substances known to be secreted by NEBs is calcitonin gene-related peptide (CGRP). The immunomodulatory functions of CGRP are well established and include induction of eosinophil chemotaxis, reduction of antigen presentation, and modulation of cytokine and chemokine secretion. The 312discussion presents an overview of the already known immunomodulatory effects of the various known NEB secretory products, including CGRP, and thus surveys the hypothetical NEB contribution to the pulmonary response to antigenic stimulation.
