Detection of a Potent Chemotactic Activity in Supernatants from Human Monocytes Stimulated with Endothelin-1 (ET-1)

Abstract

A role for the endothelial derived, potent vasoactive peptide Endothelin-1 (ET-1) in inflammatory reactions in the microvasculature has been suggested (1). We have earlier shown that ET-1 causes lung injury in an interaction with leukocytes in isolated rat lungs (2). In this work we have studied the chemotactic activity and release of cytokines in supernatants from human monocytes (MC) stimulated in vitro with different concentrations of ET-1 for 1, 4, 8, and 24 hours. For the study of chemotactic activity, a Boyden chamber was employed, and the cytokines TNF, IL-1, and IL-6 were analysed by bioassays. We found that supernatants from MC stimulated with ET-1 contained a potent chemotactic activity against MC and polymorphonuclear cells (PMN). Chemotactic activity against PMN is produced already after 1 hour of stimulation with ET-1. The effect of ET-1 is dose-dependent. The chemotactic activity against PMN does not correspond to the levels of TNF, IL-1 or IL-6 detected in the supernatants. The chemotactic activity against MC appears in the supernatants first after 24 hours of stimulation with ET-1. This chemotactic activity is also dependent on dose of ET-1 used for stimulation. The chemotactic activity against MC corresponds to the increased levels of IL-1 detected in the supernatants. To conclude, our data suggests that ET-1 may take part in inflammatory reactions, both by inducing production of cytokines and chemotactic factors.