Published online before print July 29, 2009

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(Journal of Leukocyte Biology. 2009;86:1179-1189.)
© 2009 Society for Leukocyte Biology

Kinin B₁ receptor activation turns on exocytosis of matrix metalloprotease-9 and myeloperoxidase in human neutrophils: involvement of mitogen-activated protein kinase family

Pamela Ehrenfeld^*,, Carola E. Matus^*, Francisca Pavicic^*, Cesar Toledo^*, Francisco Nualart, Carlos B. Gonzalez, Rafael A. Burgos, Kanti D. Bhoola^|| and Carlos D. Figueroa^*,1

^* Laboratorio de Patologia Celular, Instituto de Anatomia, Histologia and Patologia, and Institutos de
Fisiologia and
Farmacologia, Universidad Austral de Chile, Valdivia, Chile;
Departmento de Biologia Celular, Universidad de Concepcion, Chile; and
^|| Lung Institute of Western Australia, Centre for Asthma and Allergy Research Institute, University of Western Australia, Perth, Australia

1. Correspondence: Laboratorio de Patologia Celular, Instituto de Anatomía, Histología and Patología, Universidad Austral de Chile, Casilla 567, Valdivia, Chile. E-mail: cfiguero{at}uach.cl

ABSTRACT

During neutrophil activation and degranulation, MMP-9 and MPO are released into the extracellular space to propagate inflammatory disorders. As kinin peptides are major participants in acute inflammatory responses, and the G-protein-coupled B₁R mediates the chemotaxis of human neutrophils, we examined the release of the neutrophil enzymes MMP-9 and MPO by the B₁R agonist LDBK and determined the signaling pathways that may regulate this cellular effect. Cytochalasin-treated and -untreated neutrophils were suspended in HBSS and stimulated with a range concentration of LDBK for 5 min. Zymography and Western blotting revealed that LDBK induced the release of MMP-9 and MPO. The use of specific signaling transduction inhibitors showed that release of MMP-9 depended on ERK1/2 and p38 MAPKs, whereas release of MPO involved only the p38 cascade. Inhibition of the key steps in these pathways showed that the release of both enzymes depended on PKC and PI3K. Stimulation of neutrophils with LDBK produced phosphorylation of ERK1/2 and p38 MAPK, which was inhibited by B₁R antagonists. The phosphorylated ERK1/2 MAPK translocated to the neutrophil nucleus, suggesting that transcription of new genes may follow activation of B₁R. Our results demonstrate that in human neutrophils, activation of kinin B₁R by LDBK initiates separate signaling cascades that trigger the release of MMP-9 and MPO from tertiary and primary granules, respectively, suggesting that the B₁R plays a pivotal role in inflammatory disorders.

Key Words: degranulation • inflammation • ERK1/2 MAPK • p38 MAPK • zymography