Abstract

Endothelin (ET)-1 has been detected in many inflammatory pathologies, including rheumatoid arthritic patients, asthma, and ischemic-reperfusion injury. In this study, we have investigated the effect of a panel of different ET-1 antagonists displaying different selectivities for the receptors in a murine model of experimental inflammatory peritonitis. Systemic treatment of mice with the ETA antagonist C₃₃H₄₄N₆O₅, N-[N-[-N(hexahydro-1H-azepin-1-yl)carbonyl]-l-leucyl]-1-methyl-d-tryptophyl]-3-(2-pyridinyl)-d-alanine (FR139317) inhibited neutrophil accumulation. However, a greater degree of inhibition was observed with the ETB antagonist C₃₄H₅₁N₅O₇, N-cis-2,6-dimethylpiperidinocarbonyl-b-tBu-Ala-d-Trp(1-methoxycarbonyl)-d-Nle-OH (BQ-788) and the ET(A and B) antagonist C₅₂H₆₅N₇O₁₀, N-acetyl-α-[10,11-dihydro-5H-dibenzo-[a,d]cycloheptadien-5-yl]-d-Gly-Leu-Asp-lle-lle-Trp (PD145065); all these effects occurred without altering peripheral blood cell counts. Release of the CXC chemokine KC was significantly reduced by the FR139317 and PD145065 but not by BQ-788. Evaluation of the therapeutic potential of these antagonists showed that PD145065 inhibited neutrophil migration and KC release, whereas the others caused a nonsignificant reduction in these parameters. Parameters of endothelial cell activation showed that urate-stimulated interleukin-1β release was inhibited by BQ-788 and PD145065 but not by FR139317, whereas ET-1 was only inhibited by the mixed antagonist. A different scenario was observed with respect to release of the CXC chemokine KC with FR139317 and PD145065 being effective, whereas with a marker of polymorphonuclear activation the ETA and mixed antagonist inhibited adhesion molecule expression. These data show that ET-1 antagonists elicit different mechanisms of actions in the way they display their antimigratory effects in a murine model of monosodium urate crystal peritonitis.