Upregulation of stromal cell-derived factor-1 alpha/CXCR4 axis-induced migration of human neural progenitors by tumor necrosis factor-alpha and interleukin-8

<正>BACKGROUND:Studies of several animal models of central nervous system diseases have shown that neural progenitor cells(NPCs) can migrate to injured tissues.Stromal cell-derived factor 1 alpha (SDF-1α),and its primary physiological receptor CXCR4,have been shown to contribute to this process. OBJECTIVE:To investigate migration efficacy of human NPCs toward a SDF-1αgradient,and the regulatory roles of tumor necrosis factor-α(TNF-α) and interleukin-8(IL-8) in SDF-1α/CXCR4 axis-induced migration of NPCs. DESIGN,TIME AND SETTING:An in vitro,randomized,controlled,cellular and molecular biology study was performed at the Laboratory of Department of Cell Biology,Medical College of Soochow University between October 2005 and November 2007. MATERIALS:SDF-1αand mouse anti-human CXCR4 fusion antibody were purchased from R&D Systems,USA.TNF-αwas purchased from Biomyx Technology,USA and IL-8 was kindly provided by the Biotechnology Research Institute of Soochow University. METHODS:NPCs isolated from forebrain tissue of 9 to 10-week-old human fetuses were cultured in vitro.The cells were incubated with 0,20,and 40 ng/mL TNF-α,or 0,20,and 40 ng/mL IL-8,for 48 hours prior to migration assay.For antibody-blocking experiments,cells were further pretreated with 0,20,and 40μg/mL mouse anti-human CXCR4 fusion antibody for 2 hours.Subsequently,the transwell assay and CXCR4 blockade experiments were performed to evaluate migration of human NPCs toward a SDF-1αgradient.Serum-free culture medium without SDF-1αserved as the negative control. MAIN OUTCOME MEASURES:The transwell assay was performed to evaluate migration of human NPCs toward a SDF-1αgradient,which was blocked by fusion antibody against CXCR4.In addition, CXCR4 expression in human NPCs stimulated by TNF-αand IL-8 was measured by flow cytometry. RESULTS:Results from the transwell assay demonstrated that SDF-1αwas a strong chemoattractant for human NPCs(P<0.01),and 20 ng/mL produced the highest levels of migration. Anti-human CXCR4 fusion antibody significantly blocked the chemotactic effect(P<0.05).Flow cytometry results showed that treatment with TNF-αand IL-8 resulted in increased CXCR4 expression and greater chemotaxis efficiency of NPCs towards SDF-1α(P<0.01). CONCLUSION:These results demonstrated that SDF-1αsignificantly attracted NPCs in vitro,and neutralizing anti-CXCR4 antibody could block part of this chemotactic function.TNF-αand IL-8 increased chemotaxis efficiency of NPCs towards the SDF-1αgradient by upregulating CXCR4 expression in NPCs.