Migration and proliferation of guinea pig and human airway epithelial cells in response to tachykinins

Restoration of the epithelial lining of a damaged airway is a necessary component of airway repair. Tachykinins, including substance P (SP) and neurokinin A (NKA), are localized to sensory nerves within the airway mucosa. These tachykinins regulate several airway functions, but their role in the repair of the epithelium has not been explored. To determine whether tachykinins stimulate migration and proliferation of airway epithelial cells, guinea pig tracheal epithelial (GPTE) and human bronchial epithelial (HBE) cells were grown in primary culture for 4-5 days. Epithelial cell migration was assessed in a blindwell chemotaxis chamber, and proliferation was determined by immunohistochemistry after incorporation of the thymidine analogue 5-bromo-2'-deoxyuridine (BrdU). Both GPTE and HBE cells migrated after stimulation with 10^-11 M NKA [23.0 ± 3.6 vs. 5.4 ± 1.2 cells per 10 high-power fields (hpf), P < 0.001, n = 8 for GPTE cells; 18.4 ± 2.3 vs. 3.8 ± 0.5 cells per 10 hpf for control, P < 0.001, n = 4 for HBE cells]. Migration was stimulated within 2 h, was maximal after 6 h, and was attenuated substantially by the neurokinin 2 (NKA)-receptor antagonist SR- 48968. NKA-stimulated migration was both chemokinetic and chemotactic, and it could be blocked by inhibition of protein synthesis with cyclohexamide, inhibition of microtubular function with colchicine, or inhibition of actin microfilament elongation with cytochalasin D. Migration was also stimulated by the specific NK₁-receptor agonist Sar⁹-substance P (SP), though the magnitude of response was less than for NKA. Traversal of S phase was stimulated in GPTE cells by Sar⁹-SP but not by NKA. Treatment with 10^-10 M Sar⁹-SP increased BrdU labeling from 2.7 ± 0.7 to 12.1 ± 3.6% of all cells (P < 0.05, n = 5). Stimulation with 10^-10 M Sar⁹-SP for 72 h increased cell numbers from 143,300 ± 42,800 to 205,000 ± 42,700 (P < 0.05, n = 3). We demonstrate that NKA and Sar⁹-SP elicit migration of GPTE cells in primary culture; however, only Sar⁹-SP elicits proliferation of these cells. These data suggest that tachykinins may facilitate repair of a damaged epithelium.