The tachykinin NK1 receptor mediates the migration-promoting effect of substance P on human skin fibroblasts in culture

Fibroblast migration is an important component of the tissue response during the repair process, and substance P (SP) has been shown to exert trophic effects. In the present study, cell migration was evaluated as the distance travelled by adherent human skin fibroblasts (HF) at 96 h and by the number of individual cells moving across a filter within 5 h. In control conditions (1% calf serum) adherent fibroblasts moved from the starting line by approximately 700 microns. The addition of SP (10(-11)-10(-7) M) increased HF mobilisation in a concentration-dependent manner, with maximal activity at 10(-8) M (50% increase in migration over control). Migration of individual HF in suspension was also promoted by SP in a concentration-dependent manner, with an EC50 of 2.2 x 10(-9) M. The response produced by the maximally effective concentration of SP was equal to 65 and 90% of the effect elicited by 100 ng/ml Platelet-Derived Growth Factor A/B (PDGF A/B) on adherent and individual cells respectively. The synthetic NK1 receptor agonist [Sar9]SP-sulphone (10(-11)-10(-6) M) reproduced the SP effect. The NK2 and NK3 receptor agonists [beta Ala8]NKA(4-10) and [MePhe7]NKB were devoid of any effect. The effect of SP was antagonised by two selective antagonists of NK1 receptors, namely (+/-) CP 96,345 (10(-10)-10(-8) M) and FK 888 (10(-9)-10(-7) M), while the NK2 receptor antagonist MEN 10627 (10(-8)-10(-7) M) was not effective. Our data indicate that SP is a potent effector of fibroblast migration and the NK1 receptor is responsible for this effect. These observations further support the specific role of the NK1 receptor in mediating the trophic function of SP at the cutaneous level.