趋化因子基质细胞衍生因子1(SDF-1)及其受体CXCR4

趋化因子及其受体在免疫和炎症反应、造血以及HIV感染等方面发挥重要作用,其中基质细胞衍生因子-1SDF-1及其受体CXCR4由于在造血干细胞迁移、归巢以及HIV感染中的作用而受到关注,并对其作用机制进行了探讨,现就SDF-1及其受体CXCR4的有关内容作一综述。     

The chemokine SDF-1, stromal cell-derived factor 1, attracts early stage B cell precursors via the chemokine receptor CXCR4

In the bone marrow, progenitor (pro-) and precursor (pre-) B cells depend on close contact with stromal cells for growth and maturation. Stromal cell-derived factor 1 (SDF-1), also known as pre-B cell growth-stimulating factor, is produced by bone marrow stromal cells and was reported to act together with interleukin-7 as co-mitogen for pre-B cells. SDF-1 was recently shown to be a chemokine which is chemotactic for different types of leukocytes and acts via the chemokine receptor CXCR4. Using sorted B220⁺ bone marrow cells and several B cell lines characteristic for different stages of B lymphopoiesis, we now show that SDF-1 is a potent attractant for pro- and pre-B cells, but is inactive on B cells at later stages of development. In early B cell precursors, SDF-1 induced intracellular Ca²⁺ mobilization and in vitro migration with a potency and efficacy similar to that observed for chemokines acting on blood leukocytes. These responses were mediated via CXCR4 as they could be inhibited by an anti-receptor antibody. SDF-1 is the first chemokine shown to act on early-stage B cell precursors. Mice lacking SDF-1 die perinatally and show a severe deficiency in B lymphopoiesis. We propose that SDF-1 released from the stromal cells exerts its critical hematopoietic function by selectively attracting and confining early B cell precursors within the bone marrow microenvironment that provides the necessary factors for growth and differentiation.     

Chemokine receptor CXCR4-dependent internalization and resecretion of functional chemokine SDF-1 by bone marrow endothelial and stromal cells

Regulation of the availability of chemokine SDF-1 (CXCL12) in bone marrow is still not fully understood. Here we describe a unique function for the chemokine receptor CXCR4 expressed on bone marrow endothelial cells, which efficiently internalize circulating SDF-1, resulting in its translocation into the bone marrow. Translocated SDF-1 increased the homing of transplanted human CD34(+) hematopoietic progenitors to the bone marrow. The chemokine transporter function of CXCR4 was a characteristic of endothelial and stromal cells but not of hematopoietic cells. Thus, chemokine translocation across the blood-bone marrow barrier allows effective transfer of functional SDF-1 from the periphery to the stem cell niche in the bone marrow during both homeostasis and 'alarm' situations.     

Hypoxia- and vascular endothelial growth factor-induced stromal cell-derived factor-1alpha/CXCR4 expression in glioblastomas: one plausible explanation of Scherer's structures

The morphological patterns of glioma cell invasion are known as the secondary structures of Scherer. In this report, we propose a biologically based mechanism for the nonrandom formation of Scherer's secondary structures based on the differential expression of stromal cell-derived factor (SDF)-1alpha and CXCR4 at the invading edge of glioblastomas. The chemokine SDF-1alpha was highly expressed in neurons, blood vessels, subpial regions, and white matter tracts that form the basis of Scherer's secondary structures. In contrast, the SDF-1alpha receptor, CXCR4, was highly expressed in invading glioma cells organized around neurons and blood vessels, in subpial regions, and along white matter tracts. Neuronal and endothelial cells exposed to vascular endothelial growth factor up-regulated the expression of SDF-1alpha. CXCR4-positive tumor cells migrated toward a SDF-1alpha gradient in vitro, whereas inhibition of CXCR4 expression decreased their migration. Similarly, inhibition of CXCR4 decreased levels of SDF-1alpha-induced phosphorylation of FAK, AKT, and ERK1/2, suggesting CXCR4 involvement in glioma invasion signaling. These studies offer one plausible molecular basis and explanation of the formation of Scherer's structures in glioma patients.     

基质细胞衍生因子1及其受体CXCR4在内源性神经干细胞迁移中的作用

背景：神经干细胞具有体外、体外迁移的特性,但关于其迁移的具体机制还不十分清楚。 目的：探讨基质细胞衍生因子1及其受体CXCR4在神经干细胞体内迁移中的作用。 方法：制备脑皮质微量注射脂多糖脑损伤大鼠模型,于建模后3,5,7 d灌注取脑,采用冰冻切片免疫组织化学方法,动态监测基质细胞衍生因子1和nestin表达的时相变化。 结果与结论：免疫组织化学染色观察显示：基质细胞衍生因子1随时间推移表达的量逐渐增多。Nestin阳性细胞有明显向外延伸和迁移的迹象,尖端指向脂多糖注射区。结果可见基质细胞衍生因子1趋化体内表达其特异性受体的内源性神经干细胞向脂多糖注射区迁移。     

Production of stromal cell-derived factor-1 (SDF-1)and expression of CXCR4 in human bone marrow endothelial cells

This study investigated the production of stromal cell-derived factor-1 (SDF-1) and the expression of CXCR4 in human bone marrow endothelial cells (BMECs). Human BMEC cell line BMEC-1 cells expressed SDF-1 mRNA, and conditioned medium induced chemoattraction of CD34+ cells. Migration was not inhibited by pretreating the input cells with pertussis toxin, indicating that the chemoattractive activity was not dependent on SDF-1. Three-day culture of BMEC-1 and primary human BMEC cells produced 1,710+/-204 and 1,050+/-153 pg/mL SDF-1alpha, respectively, which was much less than primary human BM stromal cells (29,536+/-532 pg/ mL). By immuno-histochemistry, CXCR4 was detected in the endothelial cells lining sinusoids, arterioles, and venules in the bone marrow. However, cultured BMECs and BMEC-1 cells did not express CXCR4 on their surfaces. These results indicate that BMECs produce and release small amounts of SDF-1 and express CXCR4 in vivo only.     

The chemokine receptor CXCR4 is expressed within the mast cell lineage and its ligand stromal cell-derived factor-1alpha acts as a mast cell chemotaxin

In this study we provide evidence that the chemokine stromal cell-derived factor-1alpha (SDF-1alpha) acts as a mast cell chemoattractant through interactions with its receptor CXCR4 expressed on mast cell progenitors in the blood as well as on in vitro-developed and leukemic mast cells. We found expression of CXCR4 on cord blood-derived mast cells (CBMC) and on the human mast cell line HMC-1, analyzed by RNAse protection assay and flow cytometry. SDF-1alpha induced intracellular calcium mobilization in HMC-1 cells and was chemotactic for both HMC-1 cells and CBMC. The activity of SDF-1alpha was completely blocked by treating the cells with pertussis toxin, indicating the involvement of Gi-proteins in the signaling. By applying a transwell assay we could show that SDF-1alpha induces migration of a cell population in peripheral blood that is enriched for cells with the capacity to differentiate into mast cells. These findings thus suggest a mechanism by which human mast cell progenitors may be recruited from circulation into the tissue.     

Circulating bone marrow-derived osteoblast progenitor cells are recruited to the bone-forming site by the CXCR4/stromal cell-derived factor-1 pathway

Previous studies demonstrated the existence of osteoblastic cells in circulating blood. Recently, we reported that osteoblast progenitor cells (OPCs) in circulation originated from bone marrow and contributed to the formation of ectopic bone induced by implantation of a bone morphogenetic protein (BMP)-2-containing collagen pellet in mouse muscular tissue. However, the character of circulating bone marrow-derived osteoblast progenitor cells (MOPCs) and the precise mechanisms involving the circulating MOPCs in the osteogenic processes, such as signals that recruit the circulating MOPCs to the osseous tissues, have been obscure. In this report, we demonstrated for the first time that the MOPCs were mobilized from intact bones to transiently occupy approximately 80% of the mononuclear cell population in the circulating blood by BMP-2-pellet implantation. The mobilized MOPCs in the circulation did not express the hematopoietic marker CD45 on their surface, but they expressed CD44 and CXCR4, receptors of osteopontin and stromal cell-derived factor-1 (SDF-1), respectively. The MOPCs isolated from the mouse peripheral blood showed the ability to be osteoblasts in vitro and in vivo. Furthermore, the MOPCs in the circulation efficiently migrated to the region of bone formation by chemoattraction of SDF-1 expressed in vascular endothelial cells and the de novo osteoblasts of the region. These data may provide a novel insight into the mechanism of bone formation involving MOPCs in circulating blood, as well as perspective on the use of circulating MOPCs to accelerate bone regeneration in the future.     

Expression of stromal cell-derived factor-1 and of its receptor CXCR4 in liver regeneration from oval cells in rat

Stromal cell-derived factor-1 is a chemokine that plays a major role during embryogenesis. Since stromal cell-derived factor-1 and its unique receptor CXCR4 are involved in the differentiation of progenitor cells, we studied the expression of this chemokine and of its receptor in hepatic regeneration from precursor oval cells. Hepatic regeneration was induced by treating rats with 2-acetylaminofluorene, and followed by partial hepatectomy. Oval cell accumulation, which predominated in periportal regions, reached a maximum at days 9 to 14 after hepatectomy and declined thereafter. Oval cells strongly expressed stromal cell-derived factor-1 protein and mRNA. CXCR4 mRNA hepatic level paralleled the number of oval cells and in situ hybridization showed CXCR4 mRNA expression by these cells. Treatment of rats with fucoidan, a sulfated polysaccharide which binds to stromal cell-derived factor-1 and blocks its biological effects, markedly decreased oval cell accumulation in five of the seven treated rats. In conclusion, our data demonstrate an expression of stromal cell-derived factor-1 and of its receptor CXCR4 in oval cells during hepatic regeneration and strongly suggest that stromal cell-derived factor-1 stimulates the proliferation of these precursor cells through an autocrine/paracrine pathway.     

Expression of CXCR4, the receptor for stromal cell-derived factor-1 on fetal and adult human lympho-hematopoietic progenitors.

Stromal cell-derived factor-1 (SDF-1) is a CXC chemokine produced by stromal cells that acts as a chemoattractant for human CD34+ progenitor cells. We investigated the expression of CXCR4, the receptor for SDF-1, on CD34+ cells from different hematopoietic sites and developmental stages. CXCR4 was detected by flow cytometry on 37 % of fetal bone marrow (BM) [gestation weeks (gw) 14-23] and 40% of adult BM CD34+ cells. Interestingly, in fetal liver CD34+ cells, CXCR4 was expressed at lower levels at later stages (9%, gw 20-23) compared to early stages of development (39%, gw 7.5-18), suggesting a development-related change in the migratory capacity of progenitors. CXCR4 was detected at similar levels on both phenotypically primitive and committed progenitors from fetal and adult sites. However, B cell lineage progenitor and precursor cells expressed CXCR4 at the highest density (80% of BM CD34+/CD10+ pro-B cells are CXCR4+). CXCR4 was also expressed in the fetal thymus in early T cell precursors and found to be down-regulated during T cell maturation. Finally, we found that stem cell factor, alone or in combination with other cytokines, can up-modulate CXCR4 expression on CD34+ cells by three- to fourfold. In conclusion, our results suggest that CXCR4 may play an important role in the local and systemic trafficking of human CD34+ cells as well as in human B lymphopoiesis and that its expression can be modulated by cytokines.     

PI3 kinase-dependent stimulation of platelet migration by stromal cell-derived factor 1 (SDF-1)

Platelets have been regarded as static cells that do not move once they adhere to a matrix. The present study explored, whether platelets are able to migrate. In contrast to the current opinion, we found that platelets were mobile, able to migrate over a surface, and transmigrate through a transwell membrane and endothelium toward a source of stromal cell-derived factor 1 (SDF-1). Platelet migration was stimulated by SDF-1, which led to the downstream activation and phosphorylation of Wiskott–Aldrich syndrome protein. SDF-1 signaling and subsequent platelet migration could be inhibited by CXCR4-receptor blocker AMD3100, pertussis toxin, inhibition of phosphoinositol 3-kinase (PI3 kinase) with LY294002 or wortmannin, and disruption of actin polymerization with cytochalasin B. The potential of platelets to migrate in an SDF-1-mediated fashion may redefine the role of platelets in the pathophysiology of vascular inflammation, subsequent atherosclerotic degeneration, and vascular regeneration.     

间质细胞衍生因子1及其受体CXCR4在浸润性乳腺癌中的表达及其临床意义

目的 研究间质细胞衍生因子1(SDF-1)及其受体CXCR4在浸润性乳腺癌中的表达,并分析其与浸润性乳腺癌相关临床病理指标及淋巴结转移之间的关系.方法 采用免疫组织化学LSAB方法检测SDF-1/CXCR4在120例浸润性乳腺癌中的表达情况;采用地高辛标记的寡核苷酸探针进行原位杂交以检测趋化因子SDF-1在肿瘤环境中表达的部位及来源.结果 (1)SDF-1主要表达于肿瘤细胞的胞质和胞膜;SDF-1的胞质表达在淋巴结阳性组高于阴性组(P=0.033),且其表达程度与淋巴结受累数目、病理学分期、组织学分级、肿瘤大小及ER表达等指标呈正相关(P<0.05);(2)罕见SDF-1 mRNA表达的脉管内皮却可见SDF-1蛋白的表达,其表达程度与肿瘤胞质SDF-1着色正相关(P<0.01);且淋巴管内皮SDF-1的着色与淋巴结转移程度为正相关(P=0.005);血管内皮SDF-1的着色与肿瘤环境中的淋巴细胞浸润正相关(P<0.01),且同时伴有较多淋巴细胞浸润及SDF-1血管内皮着色阳性的病例,其淋巴结的转移程度分别高于仅有上述条件之一或二者均不具备的各组病例(P<0.05);(3)CXCR4也主要表达于肿瘤细胞的胞质和胞核;CXCR4的胞质表达在淋巴结阳性组高于阴性组(P<0.05),且其表达程度与淋巴结受累数目、病理学分期、组织学分级、肿瘤大小及HER2表达等呈正相关(P=0.005),而胞核的表达仅与PR的表达情况呈正相关(P<0.01);(4)瘤细胞质CXCR4与SDF-1的表达呈正相关(P=0.001).结论 浸润性乳腺癌肿瘤细胞SDF-1和CXCR4的表达与多项临床病理指标,尤其是淋巴结转移率及转移程度有关,可作为预测乳腺癌淋巴结转移及预后的免疫病理学指标,同时应注意肿瘤微环境中SDF-1的多个来源及定位的不同意义.     

Progenitor egress from the bone marrow after allergen challenge: role of stromal cell-derived factor 1alpha and eotaxin

BACKGROUND: CCR3 expression on CD34+ cells mediates migration to eotaxin in vitro. CXCR4 and stromal cell-derived factor (SDF)-1alpha are important for stem cell homing to hemopoietic compartments. OBJECTIVE: To study chemokine-mediated progenitor cell traffic in allergic inflammation. METHODS: Bone marrow (BM) aspirates were obtained at baseline from normal subjects; atopic subjects without asthma; and subjects with asthma before, 5 hours after, and 24 hours after allergen inhalation (dual and early responders). Changes in chemokine receptor expression and migration were assessed. RESULTS: Expression of CXCR4, but not CCR3, on BM CD34+ cells was greater in normal subjects compared with atopic subjects with asthma. Likewise, SDF-1alpha, but not eotaxin, stimulated a greater migrational response by BM CD34+ cells from normal subjects compared with subjects with asthma. For all subjects, a positive correlation was found between intensity of CXCR4 expression and magnitude of CD34+ cell response to SDF-1alpha. Allergen inhalation attenuated both intensity of CXCR4 expression and SDF-1alpha levels in marrow from dual compared with early responders 24 hours postallergen. In contrast, the intensity of CCR3 expression on BM CD34+ cells increased in dual compared with early responders at 24 hours postallergen. In addition, an increase in migrational responsiveness of BM CD34+ cells to eotaxin and a decrease to SDF-1alpha 24 hours postallergen was found in dual responder subjects with asthma. CONCLUSION: After allergen inhalation in subjects with asthma, a downregulation in CXCR4 intensity on BM CD34+ cells and a reduction in BM SDF-1alpha levels may reduce progenitor retention to marrow stroma promoting peripheral egress, possibly mediated by the CCR3/eotaxin axis.     

氧诱导视网膜新生血管模型中基质细胞衍生因子1的表达及机制研究

目的: 观察基质细胞衍生因子1(SDF-1)在氧诱导视网膜新生血管(OIR)模型中的表达情况,并初步研究其在OIR模型中的促新生血管生长机制。方法: 30只C57BL/6J新生小鼠随机分为2组。其中15只小鼠置于氧浓度为75%的容器内饲养5 d,再转移至正常空气下饲养5 d,作为高氧诱导组;另15只小鼠一直在正常空气中饲养,作为正常对照组。免疫组织化学方法检测视网膜SDF-1、CD14蛋白的定位及含量,real-time PCR法检测视网膜SDF-1 mRNA的表达。结果: 与正常对照组相比,高氧诱导组突破视网膜内界膜的内皮细胞核数目明显增多(P<0.01),血管分支减少,大血管扩张、迂曲。两组小鼠视网膜神经上皮均可见SDF-1和CD14阳性染色,但高氧诱导组的SDF-1和CD14含量明显高于正常对照组(均P<0.01)。并且视网膜SDF-1与CD14的蛋白含量存在正相关(r=0.898,P<0.01)。视网膜SDF-1 mRNA表达在高氧诱导组也明显高于正常对照组(P<0.01)。结论: OIR模型小鼠视网膜SDF-1表达增高,其促新生血管功能可能与CD14⁺细胞有关。     

低氧诱导肺动脉内皮细胞间质细胞衍生因子-1的表达及其调控机制

肺血管重塑（PVR）是低氧性肺动脉高压持续且难以逆转的主要原因,其主要病变表现为肺动脉壁细胞增多,但其来源和机制仍不清楚。研究表明骨髓和外周血中存在血管壁细胞的祖细胞,并且参与了PVR的形成。间质细胞衍生因子-1（SDF-1）是特异性介导干细胞归巢至骨髓,介导祖细胞归巢至损伤或缺血组织的关键因子。SDF-1表达在这些部位的血管内皮细胞,而低氧是这些部位的微环境特征,也是诱导SDF-1表达的主要原因。低氧诱导因子-1α（HIF-1α）是特异性介导细胞低氧反应的关键因子,直接调控脐静脉内皮细胞SDF-1基因的表达㈨。我们旨在探讨低氧对肺动脉内皮细胞SDF-1表达的影响及HIF-1α对其表达的调控作用。     

Phenotytic Knockout of HIV-1 Chemokine Coreceptor CXCR4 and CCR5 by Intrakines for Blocking HIV-1 Infection

Acquired immunodeficiency syndrome (AIDS) and humanimmunodeficiency virus (HIV) infection continues to bemajor global health concerns. Although highly active an-tiretroviral therapy (HAART) has led to profound and pro-longed reductions in circulating viru…