Can CXCL12/CXCR4Biology Axis Stimulate Bronchial Epithelial Cells Expressing MMMP-9in Asthma

Backgrounds:Matrix metalloproteinases (MMPs), a family of zinc and calcium-dependentendopeptidaes, digests extracellular matrix proteins and may play an important role in the pathogeneois of bronchial asthma. According to reports MMP-9is an importantmediator in asthma, which is characterized by the development of bronchialhyperresponsiveness, airway structural changes refered to as “bronchial remodelingand chronchial infiltration of the airway wall by inflammatory cels,”. Several recentstudies have shown that increased levels of MMP-9in bronchoalveolar lavage (BAL)fluid, in sputum, in bronchial biopsies from asthmatic patients, and in the plasma ofacute severe asthmatic patients. Aiway epithelial cells are capable of releasingMMP-9in response to a range of stimuli, and a lot of studies reported thatCXCL12/CXCR4biology axis can active epithelial cells expressing MMP-9and theninvolved different diseases. So we sought to investigate the role of CXCL12/CXCR4axis on MMP-9expression of bronchial epithelial cells in asthma.Object:To investigate whether CXCL12/CXCR4axis can regulate the MMP-9secretion ofasthma bronchial epithelial cellsMethods：In our experiments, human bronchial epithelial cells (16-HBE) were cultured, andimmunofluorescence were used to detect the expression of CXCL12receptor(CXCR4) in HBE cells. HBE were treated with CXCL12in the absence or presenceof IL-13, MMP-9protein levels were determined using western blot, and then wealso performed that pretreatment of HBE with12G5, which is an monoclonalantibody reacts with human CXCR4, and AMD3100, a specific inhibitor of CXCR4,to block the CXCL12/CXCR axis, then observe the changes in MMP-9proteinlevels. We also investigate if CXCL12increases protein expression of MMP-9in atime-dependent manner, experimental groups:0h2h4h6h12h24h. PD98059, achemical inhibitor of extracellular signal regulated kinase, were also used toresearch the signal pathway underlying CXCL12/CXCR4axis in HBE. To furtherconfirm the results, we also established mouse asthma model, divided into: control group, asthma group, AMD3100intervention group. HE staining observes theairway inflammation, and zymogram assays detects the MMP-9activity inbronchoalveolar lavage fluid (BALF).Results：CXCL12/CXCR4biology axis can increase the expression of MMP-9in HBEcellsa. Western blot analysis showed that compared with normal controlgroup,CXCL12significantly increased the expression of MMP-9protein in HBEcells (p<0.05), and our results also showed the effection was in a time-depedentmanner, the MMP-9expression was up-regulated at4h and peaked at6h. MMP-9expression was abolished by CXCL12inhibitors, including AMD3100,12G5Ab,however, a control antibody had no effect.b. CXCL12increased protein expression of MMP-9in HBE cells have asynergistic effect with IL-13(P<0.01)c. Western blot analysis also showed that ERK/p-ERK signal pathway wasinvolved in CXCL12-induced MMP-9expression in HBE cellsd. Using AMD3100, a specific inhibitor of CXCR4, our results indicate thatblocking this receptor has a great effect in down-regulating the inflammation ofasthma mouse, and it also can reduce the MMP-9activity in the BALF (p<0.05).Conclusion:we have demonstrated that CXCL12/CXCR4biology axis can enhance the MMP-9expression in HBE through ERK/p-ERK signal pathway, and IL-13have a synergisticeffect with CXCL12. AMD3100, a specific inhibitor of CXCR4, can significantlyattenuates allergic lung inflammation and MMP-9activity.