Endothelin-converting enzyme 1 promotes re-sensitization of neurokinin 1 receptor-dependent neurogenic inflammation.
OBJECTIVE
The metalloendopeptidase endothelin-converting enzyme 1 (ECE-1) is prominently expressed in the endothelium where it converts big endothelin to endothelin-1, a vasoconstrictor peptide. Although ECE-1 is found in endosomes in endothelial cells, the role of endosomal ECE-1 is unclear. ECE-1 degrades the pro-inflammatory neuropeptide substance P (SP) in endosomes to promote recycling and re-sensitization of its neurokinin 1 (NK(1)) receptor. We investigated whether ECE-1 regulates NK(1) receptor re-sensitization and the pro-inflammatory effects of SP in the endothelium.


METHODS
We examined ECE-1 expression, SP trafficking and NK(1) receptor re-sensitization in human microvascular endothelial cells (HMEC-1), and investigated re-sensitization of SP-induced plasma extravasation in rats.


RESULTS
HMEC-1 expressed all four ECE-1 isoforms (a-d), and fluorescent SP trafficked to early endosomes containing ECE-1b/d. The ECE-1 inhibitor SM-19712 prevented re-sensitization of SP-induced Ca2+ signals in HMEC-1 cells. Immunoreactive ECE-1 and NK(1) receptors co-localized in microvascular endothelial cells in the rat. SP-induced extravasation of Evans blue in the urinary bladder, skin and ears of the rat desensitized when the interval between two SP injections was 10 min, and re-sensitized after 480 min. SM-19712 inhibited this re-sensitization.


CONCLUSIONS
By degrading endocytosed SP, ECE-1 promotes the recycling and re-sensitization of NK(1) receptors in endothelial cells, and thereby induces re-sensitization of the pro-inflammatory effects of SP. Thus, ECE-1 inhibitors may ameliorate the pro-inflammatory actions of SP.
Cattaruzza
F
F
Departments of Surgery and Physiology, University of California, San Francisco, CA 94143-0660, USA.
Cottrell
G S
GS
Vaksman
N
N
Bunnett
N W
NW
D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000096:biosynthesis / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002199:Capillary Permeability; D002460:Cell Line; D004423:Ear / Q000098:blood supply; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism; D000072396:Endothelin-Converting Enzymes; D004730:Endothelium, Vascular / Q000166:cytology; D006801:Humans; D008297:Male; D008666:Metalloendopeptidases / Q000096:biosynthesis / Q000502:physiology*; D055806:Microvessels / Q000166:cytology; D020078:Neurogenic Inflammation / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018040:Receptors, Neurokinin-1 / Q000096:biosynthesis / Q000502:physiology*; D012867:Skin / Q000098:blood supply; D013373:Substance P / Q000378:metabolism; D001743:Urinary Bladder / Q000098:blood supply
D018040:Receptors, Neurokinin-1; D013373:Substance P; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; C000606923:ECE1 protein, human; D000072396:Endothelin-Converting Enzymes; D002118:Calcium