sdf-1及其受体在成体干细胞迁移中的作用

基质细胞衍生因子是一种干细胞趋化因子,它可以通过与其受体CXCR4结合,调控干细胞定向迁移,发挥特定的生物学效应.SDF-1/CXCR4轴在调控骨髓造血干细胞归巢、调节干/前体细胞定向迁移至靶器官促进受损组织器官再生的病理生理过程中发挥着重要的作用.本文就SDF-1/CXCR4轴在成体干细胞迁移中的作用作简要综述.     

SDF-1/CXCR4增强骨髓间质干细胞的造血支持作用

目的探讨基质细胞衍生因子-1(SDF-1)/CXCR4在骨髓间质干细胞(MSCs)支持CD34 造血干/祖细胞(HSPCs)扩增中的作用。方法在长期培养基(LTC)中,以大鼠骨髓MSCs作为饲养层体外扩增骨髓CD34 细胞,每周分别加入SDF-1、SDF-1抗体或CXCR4抗体至5周。计算CD34 细胞数和集落形成细胞(CFC)数,以评价造血支持功能。为评估SDF-1/CXCR4对CD34 细胞增殖周期的影响,进行了杀伤试验以计算增殖指数。流式细胞术检测MSCs和CD34 细胞中SDF-1与CXCR4的表达;ELISA检测MSCs和CD34 细胞培养基中SDF-1的含量。结果CD34 细胞数、CFC数和增殖指数在加入SDF-1后明显增加(P<0.01),加入SDF-1抗体或CXCR4抗体后明显减少(分别为P<0.05,P<0.01)。CD34 细胞表面表达CXCR4,MSCs则不表达;MSCs细胞内表达SDF-1,而CD34 细胞不表达。在MSCs培养基中检测到SDF-1,在CD34 细胞培养基中未发现。结论SDF-1/CXCR4在骨髓MSCs支持HSPCs扩增中起重要作用。     

HIV-1协同受体CXCR4、CCR5及相关趋化因子SDF-1在胎盘的表达

目的：研究HIV-1协同受体CXCR4、CCR5及CXCR4的特异性配体SDF-1在人胎盘组织的表达，探索HIV-1子宫内垂直传播的分子机制。方法：半定量RT-PCR检测早、中、晚孕期胎盘及早孕滋养细胞CXCR4、CCR5 mRNA水平；免疫组化和免疫细胞化学检测早孕胎盘及原代培养滋养细胞CXCR4、CCR5蛋白表达；原位杂交及免疫组化分析SDF-1在早孕胎盘的表达；ELISA测定滋养细胞SDF-1的动态分泌水平。结果：各孕期胎盘表达CXCR4及CCR5 mRNA；CXCR4蛋白定位于滋养细胞，而CCR5蛋白定位于绒毛基质中。滋养细胞可转录并翻译SDF-1，且能分泌可溶性SDF-1。结论：滋养细胞同时表达CXCR4及SDF-1，SDF-1可能通过降调CXCR4而拮抗X4-HIV-1感染胎儿细胞；R5-HIV-1或许能通过滋养层裂隙感染CCR5^#基质细胞和/或Hotbauer细胞，从而发生子宫内垂直传播。     

基质细胞衍生因子-1及其受体CXCR4在肿瘤转移中的作用

基质细胞衍生因子-1(Stromal cell-derived factor-1,SDF-1)及其受体CXCR4与人类多种肿瘤转移密切相关,CXCR4在一些肿瘤细胞系、原发肿瘤组织均呈高表达。SDF-1在肿瘤细胞潜在转移靶器官的表达量比非常规转移靶器官高,肿瘤细胞利用CXCR4与其天然配体间的趋化效应实现远距离转移。SDF-1/CXCR4驱动癌细胞转移模式的提出及其相互作用机制的深入研究对于肿瘤治疗具有重要的指导意义。     

胎盘中SDF-1/CXCR4的表达与妊娠期高血压疾病的关系

目的研究趋化因子SDF-1及其受体CXCR4在妊娠期高血压疾病患者胎盘中的表达,分析其表达水平变化与妊娠期高血压疾病发病之间的关系。方法采用免疫组织化学法检测妊娠期高血压疾病患者胎盘组织中SDF-1、CXCR4的表达强度及表达范围。结果随着妊娠期高血压疾病病情程度的加重,胎盘组织中SDF-1及CXCR4表达强度及范围均呈渐进性下降趋势,且SDF-1的表达强度及范围明显优于CXCR4的表达强度及范围。结论 SDF-1、CXCR4表达强度及范围的变化与妊娠期高血压疾病的发病有重要关系。     

过表达CXCR4/CXCR7影响人脐带间充质干细胞迁移和增殖

目的探讨SDF-1/CXCR4及SDF-1/CXCR7对人脐带间充质干细胞(h UC-MSCs)迁移和增殖活性的影响。方法用Ad-EASY腺病毒质粒系统分别构建表达CXCR4和CXCR7的重组腺病毒,感染h UC-MSCs后用FCM分别检测细胞膜的CXCR4和CXCR7受体的表达,Transwell法检测细胞迁移,MTT检测h UC-MSCs增殖活性,以及在H2O2诱导细胞毒性作用对细胞存活的影响。结果成功构建表达人源的CXCR4和CXCR7的重组腺病毒,感染后h UC-MSCs细胞膜上的CXCR4/CXCR7受体阳性表达率分别达到93.7%和78.5%(P0.01),高表达CXCR4和CXCR7均显著增强SDF-1诱导的h UC-MSCs细胞迁移,其中CXCR7效应稍弱;高表达CXCR7而不是CXCR4显著提高SDF-1诱导的h UC-MSCs增殖活性和氧化应激状态下的细胞存活率(P0.05)。结论 CXCR4/CXCR7均参与介导了SDF-1诱导的h UC-MSCs细胞迁移作用,同时CXCR7还介导了SDF-1诱导的h UC-MSCs增殖和H2O2处理损伤的保护。     

胃癌中SDF-1、CXCR4、MMP-2和MMP-9的表达及意义

目的研究趋化因子SDF-1及其受体CXCR4以及MMP-2和MMP-9在胃癌中的表达,探讨SDF-1对MMP-2和MMP-9表达的影响。方法应用免疫组化EnVision两步法检测109例胃癌组织中SDF-1、CXCR4、MMP-2和MMP-9的表达。结果 (1)SDF-1、CXCR4、MMP-2、MMP-9在胃癌组的表达阳性率分别为88.1%、56.9%、80.7%和83.4%,高于切缘对照组的47.8%、30.4%、43.4%和47.8%,差异有显著性(P<0.05);(2)SDF-1和CXCR4的表达在淋巴结转移组高于无转移组(P<0.05),SDF-1、MMP-9表达程度与淋巴结转移、组织学分级、浆膜侵犯、临床分期指标呈正相关(P<0.05);MMP-2、CXCR4表达程度与淋巴结转移、浆膜侵犯、临床分期呈正相关(P<0.05);(3)SDF-1与其受体CXCR4的表达及与MMP-2、MMP-9均呈正相关(P<0.05)。结论 (1)SDF-1、CXCR4、MMP-2和MMP-9的表达水平与胃癌的发生、侵袭及淋巴结转移密切相关,可作为预测胃癌淋巴结转移及预后的指标;(2)SDF-1/CXCR4轴可通过加强肿瘤细胞MMP-2和MMP-9分泌的途径促进肿瘤的浸润和转移,提示SDF-1可能是药物靶向治疗的重要靶点。     

黄芪甲苷对EPCs中SDF-1α/CXCR4的调控作用

目的:探讨黄芪甲苷(AS-IV)对内皮祖细胞(EPCs)中CXC趋化因子受体4(CXCR4)和基质细胞衍生因子1α(SDF-1α)的调控作用及其作用机制。方法:体外培养大鼠骨髓源性EPCs,观察应用AS-IV及CXCR4的特异性阻断剂AMD3100后EPCs的增殖、黏附、迁移、凋亡和管状结构形成能力的变化,并分析AS-IV对EPCs中SDF-1α及CXCR4的mRNA和蛋白,以及p-CXCR4蛋白水平变化的影响。结果:AS-IV可以显著提升EPCs的增殖、黏附、迁移和管状结构形成能力,减轻EPCs的凋亡,上调EPCs中SDF-1α和CXCR4的mRNA和蛋白及p-CXCR4蛋白的水平(P0.05);AMD3100可以阻断AS-IV对CXCR4的mRNA和蛋白及p-CXCR4蛋白水平的上调作用,但不影响AS-IV对SDF-1α的mRNA和蛋白水平的上调作用。结论:AS-IV可能通过调控EPCs中SDF-1α/CXCR4的表达而增强EPCs的生物学作用。     

趋化因子受体CXCR4及其配体SDF-1与强直性脊柱炎发病的相关性研究

目的：探讨趋化因子及其受体在强直性脊柱炎（AS）时的变化及其在关节炎发病机制中的作用。方法： 用含588个基因的cDNA微阵列方法比较13例AS患者和7例健康志愿者外周血单个核细胞（PBMC）基因的表达水平；用流式细胞术对PBMC表面C-X-C趋化因子受体4(CXCR4)蛋白表达水平进行检测, 并以免疫组化方法和ELISA方法检测其配体SDF-1（基质来源因子）在滑膜成纤维细胞和滑膜组织的表达情况。结果： AS的588 个基因谱和健康志愿者有明显区别，其中趋化因子受体(CXCR4)在AS外周血的单核细胞和CD8+的T淋巴细胞表达显著高于健康志愿者组(P＜0.05）。 SDF-1在AS病人的PBMC、滑液单个核细胞（SFMC）、关节液成纤维细胞和关节滑膜衬里层细胞的表达也增高。 结论： 趋化因子受体CXCR4及其产物在AS患者的PBMC表达明显增多, SDF-1在AS关节炎患者滑膜成纤维细胞和滑膜组织表达增多，提示CXCR4及其配体SDF-1这一信息通道在AS炎症病变的发展与持续中可能起重要作用。     

基质细胞衍生因子(SDF-1)及其受体CXCR4对T细胞的生物学效应

趋化因子是目前很多领域研究的热点。SDF-1/CXCR4在造血干/祖细胞动员和归巢及对肿瘤细胞的生存和播散方面均起了重要作用。同时SDF-1/CXCR4对T细胞的分化发育及活化作用也日益被深入研究。本文就SD-1/CXCR4的基本结构及对T细胞的生物学效应作简要综述。     

Transforming growth factor-beta1 increases CXCR4 expression, stromal-derived factor-1alpha-stimulated signalling and human immunodeficiency virus-1 entry in human monocyte-derived macrophages

Stromal-derived factor-1 (SDF-1/CXCL12) and its receptor CXCR4 play crucial roles in leukocyte migration and activation, as well as embryogenesis, angiogenesis, cancer and viral pathogenesis. CXCR4 is one of the major human immunodeficiency virus-1 (HIV-1) coreceptors on macrophages. In many tissues macrophages are one of the predominant cell types infected by HIV-1 and act as a reservoir for persistent infection and viral dissemination. In patients infected by HIV-1, blood and tissue levels of transforming growth factor-beta1 (TGF-beta1) are increased. The purpose of this study was to evaluate the effects of TGF-beta1 on CXCR4 expression and function in primary human monocyte-derived macrophages (MDMs) and rat microglia. TGF-beta1 up-regulated CXCR4 and enhanced SDF-1alpha-stimulated ERK1,2 phosphorylation in these cells. The increased CXCR4 expression in human MDMs resulted in increased susceptibility of the cells to entry by dual-tropic CXCR4-using HIV-1 (D-X4). In contrast, TGF-beta1 failed to increase CCR5 expression or infection by a CCR5-using virus in MDMs. Our data demonstrate that TGF-beta1 enhances macrophage responsiveness to SDF-1alpha stimulation and susceptibility to HIV-1 by selectively increasing expression of CXCR4. The results suggest that increased expression of CXCR4 on macrophages may contribute to the emergence of dual-tropic X4 viral variants at later stages of HIV-1 infection.     

The SDF-1-CXCR4 axis stimulates VEGF secretion and activates integrins but does not affect proliferation and survival in lymphohematopoietic cells

To better define the role HIV-related chemokine receptor-chemokine axes play in human hematopoiesis, we investigated the function of the CXCR4 and CCR5 receptors in human myeloid, T- and B-lymphoid cell lines selected for the expression of these receptors (CXCR4(+), CXCR4(+) CCR5(+), and CCR5(+) cell lines). We evaluated the phosphorylation of MAPK p42/44, AKT, and STAT proteins and examined the ability of the ligands for these receptors (stromal-derived factor-1 [SDF-1] and macrophage inflammatory protein-1beta [MIP-1beta]) to influence cell growth, apoptosis, adhesion, and production of vascular endothelial growth factors (VEGF), matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in these cell lines. We found that A) SDF-1, after binding to CXCR4, activates multiple signaling pathways and that in comparison with the MIP-1beta-CCR5 axis, plays a privileged role in hematopoiesis; B) SDF-1 activation of the MAPK p42/44 pathway and the PI-3K-AKT axis does not affect proliferation and apoptosis but modulates integrin-mediated adhesion to fibronectin, and C) SDF-1 induces secretion of VEGF, but not of MMPs or TIMPs. Thus the role of SDF-1 relates primarily to the interaction of lymphohematopoietic cells with their microenvironment and does not directly influence their proliferation or survival. We conclude that perturbation of the SDF-1-CXCR4 axis during HIV infection may affect interactions of hematopoietic cells with the hematopoietic microenvironment.     

Stromal-Cell Derived Factor Is Expressed by Dendritic Cells and Endothelium in Human Skin

Stromal-cell derived factor or SDF-1 is a CXC chemokine constitutively expressed by stromal bone marrow cell cultures that binds to the G-protein-coupled receptor CXCR4. SDF-1/CXCR4 represents a unique, nonpromiscuous ligand/receptor pair that plays an essential role in prenatal myelo- and lymphopoiesis as well as in cardiovascular and neural development. SDF-1 prevents entry of CXCR4-dependent (X4) HIV viruses in T lymphocytes, by binding and internalizing CXCR4. The expression pattern of SDF-1 protein in normal tissues is not known. Here we describe an analysis of SDF-1 mRNA and protein in normal and inflamed skin by in situ hybridization and immunohistochemistry, using a novel anti-SDF-1 monoclonal antibody. We also describe the expression pattern of CXCR4 receptor by immunohistochemistry. Our results show that SDF-1 protein and mRNA are normally expressed by endothelial cells, pericytes, and either resident or explanted CD1a+ dendritic cells. Epithelial cells of sweat glands but not keratinocytes also express SDF-1. In various inflammatory skin diseases, a large number of mononuclear cells and fibroblasts in close contact with CXCR4-positive lymphocytic infiltrates also express SDF-1. CXCR4 was also detected in many different normal cell types, including endothelial and epithelial cells, which points to a role for SDF-1/CXCR4 cell signaling in vascular and epithelial homeostasis. The demonstration of SDF-1 expression in dendritic and endothelial cells provides new insights into the mechanisms of normal and pathological lymphocyte circulation and makes it possible to envisage a role for locally secreted SDF-1 in the selective incapacity of mucosal dendritic cells to support and propagate infection by X4 HIV isolates.     

SDF-1 gene polymorphisms and syncytia induction in Brazilian HIV-1 infected individuals

Stromal-derived factor (SDF-1) is the principal ligand for CXCR4, a co-receptor with CD4 for T lymphocyte cell line-tropic human immunodeficiency virus-type 1 (HIV-1). A common polymorphism, SDF1-3' A, was identified in an evolutionary conserved segment of the 3' untranslated region of the SDF-1 gene. Sequence analysis revealed a common variant at position 801, a G-->A transition referred to as SDF1-3' A. Because this variant eliminates the Msp I restriction site PCR-restriction fragment length polymorphism (RFLP) analysis was used for rapid detection of genotypes. We genotyped 62 HIV infected patients and 60 non-HIV blood donors by RFLP analysis. We also assessed syncytia formation through co-culture of MT-2 cells with peripheral blood mononuclear cells from HIV patients. Syncytium-inducing HIV-1 variants have been shown to be clinically significant in the pathogenesis of HIV-1 infection. In our study, we detected a low frequency of 3'A/3'A (5%) in the blood donors but this genotype was absent in all HIV patients. We found that 41 (68%) HIV patients including syncytia inducing (SI) and non-syncytia inducing (NSI) groups contained the wild type (wt/wt) genotype for SDF-1. Our data indicate that there is no correlation between SDF-1 alleles and syncytium inducing HIV.     

Inhibitors of CXCR4 affect the migration and fate of CXCR4+ progenitors in the developing limb of chick embryos.

Chemokines and their receptors play major roles in numerous physiological and pathological processes during development and disease. CXCR4 is the most abundantly expressed chemokine receptor during development. In contrast to other chemokine receptors, CXCR4 binds and is activated exclusively by its ligand stromal derived factor-1 (SDF-1) or CXCL12. SDF-1 signaling has a wide range of effects on CXCR4-expressing cells depending on the cell type ranging from cell growth to adhesion, chemotaxis, and migration. CXCR4 also serves as a co-receptor for HIV-1 entry into T-cells and has been implicated in the pathogenesis of rheumatoid arthritis and cancer growth and invasion. Numerous inhibitors and antagonists of CXCR4 have been produced and are being tested for their efficiency to target its role in pathogenesis. Our initial expression analysis revealed that CXCR4 is expressed by the migrating myogenic and angiogenic precursors in the developing chick limb. In this study, we used the most specific peptidic inhibitors of CXCR4, T140 and its analog TN14003, to analyse the effect of blocking CXCR4/SDF-1 signaling on the undetermined bioptent migratory progenitors in the developing chick limb. Our results point to defects in migration and an altered differentiation program of these CXCR4-expressing progenitor pool in the limb.     

Mobilization of myeloma cells involves SDF-1/CXCR4 signaling and downregulation of VLA-4

Adhesion molecules and stromal cell-derived factor-1 (SDF-1)/CXCR4 signaling play key roles in homing and mobilization of hematopoietic stem cells (HSC). Active signaling through SDF-1/CXCR4 and upregulation of adhesion molecules are required for homing, whereas downregulation of adhesion molecules and disruption of SDF-1/CXCR4 signaling are required for mobilization of HSC. We studied the surface expression of CXCR4 very late activation antigen (VLA)-4 and VLA-5 on myeloma cells mobilized with cyclophosphamide and GM-CSF in 12 multiple myeloma patients undergoing HSC mobilization for autologous transplantation. We also studied the plasma levels of SDF-1 in apheresis collection of these patients. We observed a statistically significant decrease in the levels of SDF-1 and surface expression of CXCR4 on myeloma cells in four consecutive apheresis collections compared with premobilization bone marrow specimens. We also observed a statistically significant decrease in surface expression of VLA-4 in myeloma cells in the apheresis collections compared with premobilization bone marrow samples. Furthermore, myeloma cells derived from apheresis collections had decreased adhesion and trans-stromal migration in response to SDF-1, which could be reversed by short incubation with interleukin-6. Hence, mobilization of myeloma cells involves SDF-1/CXCR4 signaling and downregulation of VLA-4.     

SDF-1 increases recruitment of osteoclast precursors by upregulation of matrix metalloproteinase-9 activity

Although chemokines play essential roles in the trafficking and homing of many circulating hematopoietic cell types, their potential influences on osteoclast (OC) recruitment or bone remodeling are not well known. Therefore, chemokine receptor expression was analyzed by RNase protection assay during OC formation induced by RANKL in a murine mononuclear cell line (RAW 264.7). Relatively high CXCR4 expression was detected in RAW cells (pre-OCs), whereas CXCR4 levels were downregulated during RAW-OC development. SDF-1, the unique ligand for CXCR4, stimulated RAW cell production of matrix metalloproteinase (MMP)-9 activity, a matrix-degrading enzyme essential for pre-OC migration into the developing bone marrow cavity. Induced MMP-9 activity in RAW cells was associated with their increased MMP-dependent transmigration through a collagen gel in response to SDF-1. We conclude that SDF-1 stimulation of MMP-9 activity in pre-OCs may be a key aspect of their recruitment to bone and migration within the marrow to sites for OC differentiation and bone resorption.     

SDF-1 Increases Recruitment of Osteoclast Precursors by Upregulation of Matrix Metalloproteinase-9 Activity

Although chemokines play essential roles in the trafficking and homing of many circulating hematopoietic cell types, their potential influences on osteoclast (OC) recruitment or bone remodeling are not well known. Therefore, chemokine receptor expression was analyzed by RNase protection assay during OC formation induced by RANKL in a murine mononuclear cell line (RAW 264.7). Relatively high CXCR4 expression was detected in RAW cells (pre-OCs), whereas CXCR4 levels were downregulated during RAW-OC development. SDF-1, the unique ligand for CXCR4, stimulated RAW cell production of matrix metalloproteinase (MMP)-9 activity, a matrix-degrading enzyme essential for pre-OC migration into the developing bone marrow cavity. Induced MMP-9 activity in RAW cells was associated with their increased MMP-dependent transmigration through a collagen gel in response to SDF-1. We conclude that SDF-1 stimulation of MMP-9 activity in pre-OCs may be a key aspect of their recruitment to bone and migration within the marrow to sites for OC differentiation and bone resorption.     

Expression of SNCG,MAP2, SDF-1 and CXCR4 in gastric adenocarcinoma and their clinical significance

Objectives: The purpose of the study was to detect the expression of SNCG, MAP2, SDF-1 and CXCR4 in gastric adenocarcinoma, and to evaluate their roles in the carcinogenesis of gastric adenocarcinoma, development, invasion and metastasis as well as their clinical significance. Methods: The expression of SNCG, MAP2, SDF-1 and CXCR4 was detected by SP immunohistochemical method in 225 cases of gastric adenocarcinoma and 105 cases of nonneoplastic adjacent gastric tissue. The expression of SNCG, MAP2, SDF-1 and CXCR4 mRNA was also detected by RT-PCR method in 50 cases of gastric adenocarcinoma and 30 cases of nonneoplastic adjacent gastric tissue. Results: The expression of SNCG, MAP2, SDF-1 and CXCR4 in the gastric adenocarcinoma was remarkably higher than those in the nonneoplastic adjacent gastric tissue (P < 0.01); The positive expression of SNCG and MAP2 was correlated with the depth of tumor invasion and the metastasis of lymph nodes (P < 0.05), and that of SDF-1 and CXCR4 was correlated with the metastasis of lymph nodes (P < 0.05). Conclusions: SNCG, MAP2, SDF-1 and CXCR4 may play an important role in the carcinogenesis, progression, invasion and metastasis of gastric adenocarcinoma. However, it still needs more exploration whether they can serve as promising therapeutic targets of gastric adenocarcinoma.