CXCR4 inhibitor attenuates allergen-induced lung inflammation by down-regulating MMP-9 and ERK1/2.

Chemokine (C-X-C motif) ligand 12 (CXCL12) and its receptor chemokine receptor 4 (CXCR4) have been recognized to play a crucial role in the pathogenesis of bronchial asthma, but the underlying molecular mechanisms are yet to be fully addressed. In the present report we demonstrated that CXCL12/CXCR4 signaling mediates allergic airway inflammation through induction of matrix metalloproteinase 9 (MMP-9) in a murine asthmatic model. We noted that administration of AMD3100, a specific CXCR4 antagonist, significantly attenuated OVA-induced asthmatic responses along with reduced epithelial MMP-9 expression. Our studies in a bronchial epithelial cell line, 16HBE cells, further revealed that CXCL12/CXCR4 signaling synergizes with IL-13 to enhance epithelial MMP-9 expression. Our mechanistic studies demonstrated that CXCL12/CXCR4 enhances epithelial MMP-9 expression by inducing ERK1/2 expression and activation. Together, these studies would bring novel insight into the understanding for the role of CXCL12/CXCR4 signaling in asthmatic responses during the course of bronchial asthma development.