CXCR4 inhibitor attenuates ovalbumin-induced airway inflammation and hyperresponsiveness by inhibiting Th17 and Tc17 cell immune response.

Accumulating evidence suggests that chemokine (C-X-C motif) ligand 12 (CXCL12) and its receptor chemokine (C-X-C motif) receptor 4 (CXCR4) may contribute to the pathogenesis of allergic asthma. However, the underlying molecular mechanisms remain to be fully understood. T-helper 17 cells (Th17) and T-cytotoxic 17 cells (Tc17) have been implicated in the development of several allergic disorders, including asthma. The present study aimed to explore the association between CXCL12 signaling and Th17/Tc17 cells in the development of asthma. Ovalbumin (OVA)-sensitized BALB/c mice were treated with AMD3100, a specific CXCR4 antagonist, prior to OVA challenge. Following the final allergen (OVA) challenge, airway responsiveness to methacholine, influx of inflammatory cells to the airway, and cytokine levels in the bronchoalveolar lavage fluids (BALF) and lung homogenate were assessed. Interleukin (IL)-17-expressing CD3+CD8- lymphocytes (Th17 cells) and IL-17+CD3+CD8+ lymphocytes (Tc17 cells) isolated from lung tissue samples were detected by flow cytometry. The results of the present study demonstrated that administration of AMD3100 significantly decreased airway responsiveness to methacholine, attenuated the influx of inflammatory cells to the airway and reduced the levels of IL-4, IL-5 and IL-13 in the BALF. Furthermore, AMD3100 significantly reduced the increased number of lung Th17 and Tc17 cells as well as the levels of IL-17 in the lung homogenate induced by OVA challenge. In conclusion, the CXCR4 inhibitor suppresses the asthmatic response, which is associated with attenuation of the Th17 and Tc17 cell immune response.

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.