Substance P activates coincident NF-AT- and NF-κB-dependent adhesion molecule gene expression in microvascular endothelial cells through intracellular calcium mobilization

Upon stimulation, cutaneous sensory nerves release neuropeptides such as substance P (SP), which modulate responses in the skin by activating a number of target cells via neurokinin receptors. We have demonstrated that SP preferentially binds to the NK-1R on human dermal microvascular cells, resulting in increased intracellular Ca²⁺ and induction of ICAM-1 and VCAM- 1 expression. In the current studies, we identify specific elements in the regulatory regions of ICAM-1 and VCAM-1 genes as necessary and sufficient for SP-dependent transcriptional activation. SP treatment of human dermal microvascular endothelial cells leads to coincident activation and binding of the transcription factor NF-AT to the -191/-170 region of the ICAM-1 gene (a region bound by activated p65/p65 homodimers in response to TNF-α), and NF- κB (p65/p50) to tandem NF-κB binding sites at -76/-52 of the VCAM-1 gene. The SP-elicited intracellular Ca²⁺ signal was required for activation and subsequent binding of both NF-AT and NF-κB. The transacting factor induction by SP was specific, since a selective NK-1R antagonist blocked SP activation and subsequent NF-AT and NF-κB activation and binding. These data demonstrate coincident activation of NF-AT and NF-κB via SP-induced intracellular Ca²⁺ mobilization and indicate a crucial role for neuropeptides in modulating localized cutaneous inflammatory responses.