Substance P increases neutrophil adhesion to human umbilical vein endothelial cells

1 Adhesion of neutrophils (PMNs) to vascular endothelial cells (EC) is a critical step in recruitment and infiltration of leukocytes into tissues during inflammation. Substance P (SP), a neuropeptide released from sensory nerves, evoked PMN adhesion to EC. The NK receptor subtype(s) and the cell type( s) involved were investigated. 2 SP was coincubated with human PMNs and EC from the human umbilical vein ( HUVEC); adhesion was quantitated by computerised microimaging fluorescence analysis. 3<LF>The proadhesive effects of SP (range 10(-18) - 10(-6) M) were illustrated in a biphasic dose - response curve, with a maximum at 10(-15) M (276 +/- 16% adhesion vs control; P<0.01) and another one at 10(-10) M (200 +/- 18% adhesion vs control; P<0.01). Neurokinin A was less active and neurokinin B was inactive. The adhesion molecules LFA-1 and OKM-1, but not selectins, were involved according to results with selective mAbs. 4 The NK1 agonist [Sar(9), Met(O-2)(11)] SP reproduced the effects of SP, whereas the NK2 agonist [betaAla(8)]- neurokininA (4 - 10) acted at 10(-13) - 10(-8) m only. The NK3 agonist, senktide, was ineffective. 5 The NK1 antagonists, CP 96,345 and L 703,606 (both 10(-6) M), abolished the effect of 10(-15) M SP and inhibited that of 10(-10) M SP by 56+/-5% (P<0.01). By comparison, the NK2 antagonist, SR 48,968 (10(-7) m), partially antagonised the adhesion evoked by 10(-10) M SP (% inhibition: 61+/-6; P<0.05). 6 Since preincubation of PMNs and HUVEC with SP gave the same results it is clear that both cell types contributed to its proadhesive effects. 7 These results indicate that SP induced a proadhesive effect during inflammatory processes, which was mediated by NK1 and NK2 receptors.