MMP-12 induces IL-8/CXCL8 secretion through EGFR and ERK1/2 activation in epithelial cells

1 Institut National de la Santé et de la Recherche Médicale (INSERM) U620, Université de Rennes 1, Rennes, France, and 2 Merck-Serono International S.A., Geneva, Switzerland Submitted 28 November 2007 ; accepted in final form 3 April 2008 Macrophage metalloelastase (MMP-12) is described to be involved in pulmonary inflammatory response. To determine the mechanisms linking MMP-12 and inflammation, we examined the effect of recombinant human MMP-12 (rhMMP-12) catalytic domain on IL-8/CXCL8 production in cultured human airway epithelial (A549) cells. Stimulation with rhMMP-12 resulted in a concentration-dependent IL-8/CXCL8 synthesis 6 h later. Similar results were also observed in cultured BEAS-2B bronchial epithelial cells. In A549 cells, synthetic matrix metalloproteinase (MMP) inhibitors prevented rhMMP-12-induced IL-8/CXCL8 release. We further demonstrated that in A549 cells, rhMMP-12 induced transient, peaking at 5 min, activation of ERK1/2. Selective MEK inhibitors (U0126 and PD-98059) blocked both IL-8/CXCL8 release and ERK1/2 phosphorylation. IL-8/CXCL8 induction and ERK1/2 activation were preceded by EGF receptor (EGFR) tyrosine phosphorylation, within 2 min, and reduced by selective EGFR tyrosine kinase inhibitors (AG-1478 and PD168393 ) by a neutralizing EGFR antibody and by small interfering RNA oligonucleotides directed against EGFR, implicating EGFR activation. In addition, we observed an activation of c-Fos in A549 cells stimulated by rhMMP-12, dependent on ERK1/2. Using small interfering technique, we showed that c-Fos is involved in rhMMP-12-induced IL-8/CXCL8 production. From these results, we conclude that one mechanism, by which MMP-12 induces IL-8/CXCL8 release from the alveolar epithelium, is the EGFR/ERK1/2/activating protein-1 pathway. metalloelastase; alveolar epithelium; chemokine Address for reprint requests and other correspondence: V. Lagente, Laboratoire de Pharmacodynamie et de Pharmacologie Moléculaire, INSERM U620, Université de Rennes 1, 2. Ave. du Professeur Léon Bernard, CS 34317, 35043 Rennes Cedex, France (e-mail: vincent.lagente{at}univ-rennes1.fr )