Inactivation of endothelin by polymorphonuclear leukocyte-derived lytic
enzymes
P Patrignani, A Del Maschio, G Bazzoni, L Daffonchio, A Hernandez, R Modica, L Montesanti, D Volpi, C Patrono and E Dejana
University of Chieti G. D'Annunzio, School of Medicine, Italy.
Cultured bovine aortic endothelial cells (BAEC) released endothelin-1
(ET-1) in the culture medium in a time-dependent fashion. Coincubation of
fMLP-activated human polymorphonuclear leukocytes (PMN) with BAEC caused a
fast (maximal activity was reached within 15 minutes) and cell
number-dependent disappearance of ET-1 from the medium. This effect was
direct to ET-1, because it was also present when PMN were incubated with
the synthetic peptide in the absence of BAEC. PMN-dependent disappearance
of ET-1 was associated with loss of constrictor activity on isolated rabbit
aorta. PMN-released products were responsible for ET- 1 degrading activity,
because supernatants of activated PMN were equally effective as the intact
cells. Resting PMN, in the same time frame, were uneffective. Eglin C, a
potent blocker of PMN-derived elastase and cathepsin G, reversed the ET-1
inhibitory activity of fMLP- stimulated PMN and of their supernatant.
Direct addition of elastase and cathepsin G to synthetic ET-1 destroyed its
immunoreactivity and this effect was blocked by eglin C. High-performance
liquid chromatography (HPLC) analysis supported the hypothesis that ET-1
degradation by PMN was due to enzymatic proteolysis. These data provide
evidence that activated PMN are able to degrade ET-1 through the release of
proteases. Because physiologic concentrations of PMN can destroy high
amounts (up to 100 nmol/L) of ET-1 within a few minutes, we propose that
this mechanism of ET-1 inactivation has biologic relevance.
Volume 78,
Issue 10,
pp. 2715-2720,
11/15/1991
Copyright © 1991 by The American Society of Hematology
