A novel bioactive 31-amino acid ET-1 peptide stimulates eosinophil recruitment and increases the levels of eotaxin and IL-5

Abstract.

Objective and design: Investigation of the role of a novel inflammatory mediator 31-amino acid endothelin-1 [ET-1(1-31)], a major ET derivative in granulocytes, in eosinophil recruitment after its subcutaneous administration to mice.¶Methods: Various ET-1 derivatives (100 pmol), with or without ET receptor antagonists (200 pmol), were administered subcutaneously to mice, and then the eosinophil migration into and chemokine levels in the injected loci were analyzed.¶Results: ET-1(1-31) and a 21-amino acid endothelin-1 (ET-1), but not big ET-1, induced eosinophil migration into the injected loci with a peak after administration for 12 h, and increased the levels of eotaxin and interleukin-5 with peaks at 6 and 24 h, respectively. These effects of ET-1(1-31) and ET-1 were significantly inhibited by an ET_A receptor antagonist, BQ-123, but not by an ET_B receptor antagonist, BQ-788.¶Conclusion: Novel bioactive ET-1(1-31) induces local eosinophil migration, and increases in eotaxin and interleukin-5 through an ET_A or ET_A-like receptor.