Proliferation of guinea pig tracheal epithelial cells in coculture with rat dorsal root ganglion neural cells
White, S.R.; Garland, A.; Gitter, B.; Rodger, I.; Alger, L.E.; Necheles, J.; Nawrocki, A.R.; Solway, J.
American Journal of Physiology 268(6 Pt 1): L957-L965
1995
ISSN/ISBN: 0002-9513 PMID: 7611437 Document Number: 441743
Neuropeptides secreted by sensory afferent nerves in airways may modulate growth of airway epithelial cells. To determine whether airway sensory C-fiber nerves secrete neuropeptides that stimulate airway epithelial cell proliferation, we measured S-phase traversal in guinea pig tracheal epithelia) (GPTE) cells after coculture with rat dorsal root ganglion (DRG) cells. GPTE cells were grown in subconfluent culture on collagen-coated filters for 2 days. DRG cells were harvested from newborn rat pups and grown in primary culture for 7-10 days in separate wells. GPTE and DRG cells then were cocultured for 48 h, and 10 mM bromodeoxyuridine (BrdU), a thymidine analogue, was added in the final 24 h. Control GPTE cells were grown under similar conditions but without DRG cells. Coculture with DRG cells stimulated GPTE cell traversal of S phase. BrdU labeling in cocultured GPTE cells was 42.8 +- 5.8 compared with 18.1 +- 7.2% in control GPTE cells (P lt 0.001, n = 6). Coculture in the presence of either the neurokinin (NK)-1 receptor antagonists LY-297911 or CP-99,994, the NK-2 receptor antagonist SR-48,968, or the calcitonin gene-related peptide (CGRP) receptor antagonist hCGRP-(8-37) (10-7 M of each) during coculture attenuated proliferation of GPTE cells. Treatment with all three antagonists together during coculture decreased BrdU labeling to 2.4 +- 0.9% of labeled cells vs. 8.5 +- 0.5% of labeled cells during coculture without antagonists (n = 4, P lt 0.02). DRG cells in coculture secreted substantial concentrations of CGRP (71.0 +- 11.3 (+-SE) pmol/ml), substance P (1.26 +- 0.35 pmol/ml), and neurokinin A (0.45 +- 0.10 pmol/ml) (n = 19 for each). Proliferation was stimulated in GPTE cells by treatment with NK-1, NK-2, and CGRP-1 receptor agonists in primary culture. We conclude that rat DRG cells secrete neuropeptides that stimulate GPTE cell growth in coculture and that this effect is mediated by NK-1, NK-2, and CGRP-1 receptors. These data suggest that airway sensory nerves may modulate epithelial cell proliferation.