CXC Chemokine Receptor 4 Axis Research Articles

The role of SDF-1/CXCR4 on airway inflammation and airway remodeling in a rat asthma model

To explore the roles of stromal cell-derived factor 1 (SDF-1) and C-X-C chemokine receptor 4 (CXCR4) on airway inflammation and airway remodeling in rat asthma models. Eighteen female SD rats were randomly divided into 3 groups (n = 6): control group, asthmatic 4 weeks group and asthmatic 8 weeks group. The rats were sensitized and inhaled ovalbumin (OVA). After the asthma model was successfully established, the airway pressure was measured. The methods of HE staining and Image-Pro Plus image analysis software were used to detect the changes of eosinophils (EOS), the perimeter of inner bronchial lumen, the wall area, the area of bronchial smooth muscle and the number of smooth muscle cells of airway walls. RT-PCR and Western-blot were used to detect the expression of SDF-1 and CXCR4 in lung tissues among the 3 groups.Immunohistochemistry was used to detect the expression of SDF-1 in airway walls. Compared with the control group, the airway responsiveness, the count of EOS, the area of bronchial wall, the area of bronchial smooth muscle, the number of smooth muscle cells of airway walls in the asthmatic 4 weeks and asthmatic 8 weeks were significantly increased, and significant difference between the 2 asthmatic groups was also observed in the above indexes (P < 0.01) .RT-PCR showed that compared with the control group (SDF-1 was 0.146 ± 0.003 and CXCR4 was 0.281 ± 0.002) , the expression of SDF-1 (0.583 ± 0.004 and 0.724 ± 0.008) and CXCR4 (0.467 ± 0.003 and 0.655 ± 0.002) in lung tissues in the asthmatic 4 weeks and asthmatic 8 weeks were significantly increased (P < 0.01) . In addition, compared with the asthmatic 4 weeks group, the expression of SDF-1 and CXCR4 in lung tissues in the 8 weeks asthmatic group were significantly increased (P < 0.01) . Compared with the control group (0.180 ± 0.009) , the expression of SDF-1 in airway walls in the asthmatic 4 weeks and asthmatic 8 weeks groups (0.270 ± 0.006 and 0.350 ± 0.009) were significantly increased (P < 0.01) . In addition, compared with the asthmatic 4 weeks group, the expression of SDF-1 in airway walls in the 8 weeks asthmatic group was significantly increased (P < 0.01) . The expression of SDF-1 and CXCR4 was correlated positively with the airway responsiveness, the number of EOS, the area of bronchial wall, the area of bronchial smooth muscle and the number of smooth muscle cells of airway walls (P < 0.01). SDF-1/CXCR4 axis may play a key role in airway inflammation and airway remodeling of asthma.

SDF-1/CXCR4 axis in Tie2-lineage cells including endothelial progenitor cells contributes to bone fracture healing.

CXC chemokine receptor 4 (CXCR4) is a specific receptor for stromal-derived-factor 1 (SDF-1). SDF-1/CXCR4 interaction is reported to play an important role in vascular development. On the other hand, the therapeutic potential of endothelial progenitor cells (EPCs) in fracture healing has been demonstrated with mechanistic insight of vasculogenesis/angiogenesis and osteogenesis enhancement at sites of fracture. The purpose of this study was to investigate the influence of the SDF-1/CXCR4 pathway in Tie2-lineage cells (including EPCs) in bone formation. We created CXCR4 gene conditional knockout mice using the Cre/loxP system and set two groups of mice: Tie2-Cre(ER) CXCR4 knockout mice (CXCR4(-/-) ) and wild-type mice (WT). We report here that in vitro, EPCs derived from of CXCR4(-/-) mouse bone marrow demonstrated severe reduction of migration activity and EPC colony-forming activity when compared with those derived from WT mouse bone marrow. In vivo, radiological and morphological examinations showed fracture healing delayed in the CXCR4(-/-) group and the relative callus area at weeks 2 and 3 was significantly smaller in CXCR4(-/-) group mice. Quantitative analysis of capillary density at perifracture sites also showed a significant decrease in the CXCR4(-/-) group. Especially, CXCR4(-/-) group mice demonstrated significant early reduction of blood flow recovery at fracture sites compared with the WT group in laser Doppler perfusion imaging analysis. Real-time RT-PCR analysis showed that the gene expressions of angiogenic markers (CD31, VE-cadherin, vascular endothelial growth factor [VEGF]) and osteogenic markers (osteocalcin, collagen 1A1, bone morphogenetic protein 2 [BMP2]) were lower in the CXCR4(-/-) group. In the gain-of-function study, the fracture in the SDF-1 intraperitoneally injected WT group healed significantly faster with enough callus formation compared with the SDF-1 injected CXCR4(-/-) group. We demonstrated that an EPC SDF-1/CXCR4 axis plays an important role in bone fracture healing using Tie2-Cre(ER) CXCR4 conditional knockout mice.

Matrix metalloproteinase-1-mediated mesenchymal stem cell tumor tropism is dependent on crosstalk with stromal derived growth factor 1/C-X-C chemokine receptor 4 axis.

Human bone marrow-derived mesenchymal stem cells (MSCs) have the unique ability to home toward injuries or tumor sites. We have previously shown that the tumor-tropic property is dependent on the intrinsic expression and activity of the matrix remodeling gene, matrix metalloproteinase 1 (MMP-1). Herein, crosstalk between MMP-1/protease activated receptor 1 (PAR-1) and the G-protein coupled receptor stromal-derived growth factor 1 (SDF-1)/C-X-C chemokine receptor 4 (CXCR-4) in facilitating cell migration was investigated. Gain-of-function and RNA interference (RNAi) technology were used to evaluate the interplay between the key players. The downstream effect on the tumor-tropic migration of MSCs was investigated using modified Boyden chamber assay. Neutralizing PAR-1 activation using monoclonal antibody and targeted knockdown of MMP-1 using RNAi resulted in decreased expression of SDF-1, which was not observed in control-RNAi-transfected cells. Overexpression of CXCR-4 failed to promote MSC migration; the percentage of migrated cells toward tumor cell conditioned medium was similar to the vector-transduced and the CXCR-4-transduced MSCs. Furthermore, inhibition of SDF-1/CXCR-4 signaling using AMD3100 reduced MSC migration through the deregulation of MMP-1 promoter activities, protein expression, and metalloproteinase activity. Collectively, our results showed that MMP-1-mediated MSC tumor tropism is dependent on crosstalk with the SDF-1/CXCR-4 axis.

The SDF-1/CXCR4 axis regulates migration of transplanted bone marrow mesenchymal stem cells towards the pancreas in rats with acute pancreatitis

Stromal cell-derived factor-1 (SDF-1) and its receptor, CXC chemokine receptor-4 (CXCR4), are important regulators in the migration of bone marrow mesenchymal stem cells (BMSCs). However, the mechanisms underlying this effect in acute pancreatitis (AP) have not been investigated. In this study, BMSCs were identified by specific cell surface markers and differentiation potentials, and labeled with chloromethylbenzamido-1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (CM-Dil) for in vivo cell tracking. AP was induced by retrograde infusion of sodium taurocholate into the common bile duct in rats. The expression of SDF-1 in the injured pancreas was determined by immunohistochemistry and western blot analysis. BMSCs were incubated with or without anti-CXCR4 antibody and the contribution of SDF-1 to the migration of BMSCs was investigated. Our results demonstrated that the expression of SDF-1 was significantly increased in the injured pancreas, and that these levels peaked on days 5–7 and began to decrease on day 10. SDF-1 induced a dose-dependent migration of BMSCs in an in vitro transwell migration assay, which was almost completely blocked by AMD3100 (CXCR4-specific antagonist) or anti-CXCR4 antibody. In addition, by encouraging the migration of CM-Dil-labeled BMSCs, the SDF-1/CXCR4 axis facilitated the repair of the injured pancreas. This effect was inhibited by the anti-CXCR4 antibody. Taken together, these results indicate that the interaction of locally produced SDF-1 with CXCR4 on BMSCs, has an important regulatory role in the migration of BMSCs towards the injured pancreas in AP.

Transplantation of bone marrow mesenchymal stem cells pretreated with valproic acid in rats with an acute spinal cord injury.

This study aimed to investigate whether valproic acid (VPA) pretreatment enhances the therapeutic effectiveness of mesenchymal stem cells derived from bone marrow (BMSCs) transplanted into rats with an acute spinal cord injury (SCI). BMSCs were pretreated with VPA before transplantation and then intravenously injected 1 week after SCI. Before transplantation, levels of CXC chemokine receptor 4 (CXCR4) expression in BMSCs were tested using quantitative real-time PCR and Western blotting. Stromal derived factor-1 (SDF-1), the unique ligand of CXCR4, was quantified using RT-PCR and immunofluorescence. The locomotor function of rats with an SCI was evaluated using the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale. Fluorescence microscopy and hematoxylin-eosin (HE) staining were also performed to evaluate pathophysiological changes after transplantation. On day 7 after SCI, the level of SDF-1 expression peaked. CXCR4 expression increased significantly in BMSCs pretreated with VPA. After intravenous transplantation, BrdU-labeled BMSCs were noted at the spinal injury site, and this was especially true for BMSCs pretreated with VPA. More significant functional improvement was observed in rats receiving BMSCs pretreated with VPA than in other groups of rats. AMD3100 partially inhibited improvement. This study demonstrates that pretreatment with VPA before transplantation enhances the therapeutic benefits of BMSCs in terms of greater cell migration and better neurological outcomes after traumatic SCI. The mechanism of this enhancement may be related to the SDF-1/CXCR4 axis. Therefore, pretreatment of BMSCs with VPA warrants further study in relation to the treatment of traumatic SCI.

Over-expression of CXCR4 on mesenchymal stem cells protect against experimental colitis via immunomodulatory functions in impaired tissue

Bone marrow-derived mesenchymal stem cells (BMSCs) are attractive candidates for tissue regeneration and immunoregulation in inflammatory bowel disease. However, their in vivo reparative capability is limited owing to barren efficiency of BMSCs to injury region. Stromal cell-derived factor (SDF-1) plays an important role in chemotaxis and stem cell homing through interaction with its specific receptor CXC chemokine receptor 4 (CXCR4). The present study was designed to investigate the role of SDF-1α/CXCR4 axis in the therapeutic effects of lentivirus-preconditioned BMSCs for 2,4,6-trinitrobenzene sulfonic acid (TNBS)-colitis rats. BMSCs were isolated from female Sprague-Dawley rats and identified by flow cytometry. Lentiviral transduction was applied to over-express CXCR4/GFP (Ad-CXCR4-BMSCs) or null/GFP (Ad-GFP-BMSCs). Efficacy of engraftment was determined by the presence of enhanced green fluorescent protein (GFP) positive cells. One week after intravenous administration, Ad-GFP-BMSCs failed to colonize in the inflamed colon and had no beneficial effect in TNBS-induced colitis. Instead, Ad-CXCR4-BMSCs signally ameliorated both clinical and microanatomical severity of colitis. Immunofluorescence and western blotting showed that Ad-CXCR4-BMSCs migrated toward inflamed colon was more efficient than Ad-GFP-BMSCs. The therapeutic effect of Ad-CXCR4-BMSCs was mediated by the suppression of pro-inflammatory cytokines and STAT3 phosphorylation in injured colon. Collectively, our data indicated that over-expression CXCR4 led to enhance in vivo mobilization and engraftment of BMSCs into inflamed colon where these cells can function as an anti-inflammatory and immunomodulatory component of the immune system in TNBS-induced colitis.

SDF-1α upregulation of MMP-2 is mediated by p38 MAPK signaling in pancreatic cancer cell lines

Pancreatic cancer is highly invasive and is currently the fourth leading cause of cancer death worldwide. CXC chemokine receptor-4 (CXCR4) is a G protein-coupled receptor for CXC chemokine ligand 12/stromal cell-derived factor-1α (SDF-1α), a member of a large family of small, structurally related, heparin-binding chemokine proteins. SDF-1α/CXCR4 plays an important role in tumor growth, invasion, metastasis, and angiogenesis. SDF-1α and CXCR4 are upregulated in many tumors, including pancreatic cancer tissues, and preliminary data indicate that the SDF-1/CXCR4 axis plays an important role in tumor invasion. However, their precise role and the mechanism through which they function remain largely unknown. In this study, analysis of SDF-1α, CXCR4 and MMP-2 expression in pancreatic cancer and adjacent tissue samples from ten patients revealed that all three proteins are overexpressed in human pancreatic cancer. SDF-1α induced MMP-2 and MMP-9 upregulation in PANC-1 and SW-1990 cells, which was associated with increased pancreatic cancer cell proliferation and invasion. Furthermore, SDF-1α induced p38 phosphorylation and p38 inhibition reduced both the level of SDF-1α-stimulated MMP-2 expression and PANC-1 cell invasion. Overall, our results demonstrate that SDF-1α/CXCR4 upregulates MMP-2 expression and induces pancreatic cancer cell invasion in PANC-1 and SW-1990 cell lines by activating p38 MAPK.

Stromal Cell-Derived Factor-1β Mediates Cell Survival through Enhancing Autophagy in Bone Marrow-Derived Mesenchymal Stem Cells

Bone marrow-derived mesenchymal stem/stromal cells (BMSCs) hold great potential for cell-based therapy, yet the therapeutic efficacy remains uncertain. Transplanted BMSCs often fail to engraft within the bone marrow (BM), in part due to the poor survival of donor cells in response to inflammatory reactions, hypoxia, oxidative stress, or nutrient starvation. Two basic cell processes, apoptosis and autophagy, could potentially be responsible for the impaired survival of transplanted BMSCs. However, the functional relationship between apoptosis and autophagy in BMSC homeostasis is complex and not well understood. The stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) signaling axis appears to be critical in maintaining proliferation and survival of BM stem cell populations through improving cell proliferation and survival in response to stress; however, the exact mechanisms remain unclear. We recently described novel genetically engineered Tet-Off-SDF-1β BMSCs, which over-express SDF-1β under tight doxycycline-control, thus providing an ideal model system to investigate the isolated effects of SDF-1β. In this study we tested the hypothesis that SDF-1β can mediate cell survival of BMSCs in vitro through increasing autophagy. We found that SDF-1β had no effect on BMSC proliferation; however, SDF-1β significantly protected genetically engineered BMSCs from H2O2-induced cell death through increasing autophagy and decreasing caspase-3-dependent apoptosis. Taken together, we provide novel evidence that the SDF-1/CXCR4 axis, specifically activated by the SDF-1β isoform, plays a critical role in regulating BMSC survival under oxidative stress through increasing autophagy.

Transfusion of CXCR4-Primed Endothelial Progenitor Cells Reduces Cerebral Ischemic Damage and Promotes Repair in db/db Diabetic Mice

This study investigated the role of stromal cell-derived factor-1α (SDF-1α)/CXC chemokine receptor 4 (CXCR4) axis in brain and endothelial progenitor cells (EPCs), and explored the efficacy of CXCR4 primed EPCs in treating ischemic stroke in diabetes. The db/db diabetic and db/+ mice were used in this study. Levels of plasma SDF-1α and circulating CD34+CXCR4+ cells were measured. Brain SDF-1α and CXCR4 expression were quantified at basal and after middle cerebral artery occlusion (MCAO). In in vitro study, EPCs were transfected with adenovirus carrying null (Ad-null) or CXCR4 (Ad-CXCR4) followed with high glucose (HG) treatment for 4 days. For pathway block experiments, cells were pre-incubated with PI3K inhibitor or nitric oxide synthase (NOS) inhibitor for two hours. The CXCR4 expression, function and apoptosis of EPCs were determined. The p-Akt/Akt and p-eNOS/eNOS expression in EPCs were also measured. In in vivo study, EPCs transfected with Ad-null or Ad-CXCR4 were infused into mice via tail vein. On day 2 and 7, the cerebral blood flow, neurologic deficit score, infarct volume, cerebral microvascular density, angiogenesis and neurogenesis were determined. We found: 1) The levels of plasma SDF-1α and circulating CD34+CXCR4+ cells were decreased in db/db mice; 2) The basal level of SDF-1α and MCAO-induced up-regulation of SDF-1α/CXCR4 axis were reduced in the brain of db/db mice; 3) Ad-CXCR4 transfection increased CXCR4 expression in EPCs and enhanced EPC colonic forming capacity; 4) Ad-CXCR4 transfection prevented EPCs from HG-induced dysfunction (migration and tube formation) and apoptosis via activation of PI3K/Akt/eNOS signal pathway; 4) Ad-CXCR4 transfection enhanced the efficacy of EPC infusion in attenuating infarct volume and promoting angiogenesis and neurogenesis. Our data suggest that Ad-CXCR4 primed EPCs have better therapeutic effects for ischemia stroke in diabetes than unmodified EPCs do.

Évolution de la fonction respiratoire après dix ans de plongée professionnelle

To investigate whether transmyocardial drilling revascularization combined with heparinized basic fibroblast growth factor (bFGF)-incorporating degradable stent implantation (TMDRSI) can promote myocardial regeneration after acute myocardial infarction (AMI).A model of AMI was generated by ligating the mid-third of left anterior descending artery (LAD) of miniswine. After 6 h, the animals were divided into none-treatment (control) group (n = 6) and TMDRSI group (n = 6). For TMDRSI group, two channels with 3.5 mm in diameter were established by a self-made drill in the AMI region, into which a stent was implanted. Expression of stromal cell-derived factor-1α (SDF-1α) and CXC chemokine receptor 4 (CXCR4), cardiac stem cell (CSC)-mediated myocardial regeneration, myocardial apoptosis, myocardial viability, and cardiac function were assessed at various time-points.Six weeks after the operation, CSCs were found to have differentiated into cardiomyocytes to repair the infarcted myocardium, and all above indices showed much improvement in the TMDRSI group compared with the control group (P < 0.001).The new method has shown to be capable of promoting CSCs proliferation and differentiation into cardiomyocytes through activating the SDF-1/CXCR4 axis, while inhibiting myocardial apoptosis, thereby enhancing myocardial regeneration following AMI and improving cardiac function. This may provide a new strategy for myocardial regeneration following AMI.

Paradoxical Downregulation of CXC Chemokine Receptor 4 Induced by Polyphemusin II-Derived Antagonists

CXC chemokine receptor 4 (CXCR4) is a G protein-coupled receptor implicated in cell entry of T-cell line-tropic HIV-1 strains. CXCR4 and its ligand stromal cell derived factor-1 (SDF-1)/CXCL12 play pivotal parts in many physiological processes and pathogenetic conditions (e.g., immune cell-homing and cancer metastasis). We previously developed the potent CXCR4 antagonist T140 from structure-activity relationship studies of the antimicrobial peptide polyphemusin II. T140 and its derivatives have been exploited in biological and biomedical studies for the SDF-1/CXCR4 axis. We investigated receptor localization upon ligand stimulation using fluorescent SDF-1 and T140 derivatives as well as a specific labeling technique for cellular-membrane CXCR4. Fluorescent T140 derivatives induced translocation of CXCR4 into the perinuclear region as observed by treatment with fluorescent SDF-1. T140 derivative-mediated internalization of CXCR4 was also monitored by the coiled-coil tag-probe system. These findings demonstrated that the CXCR4 antagonistic activity and anti-HIV activity of T140 derivatives were derived (at least in part) from antagonist-mediated receptor internalization.

Isolation and Identification of CXCR4-positive Cells from Human Dental Pulp Cells

IntroductionIn previous studies, we found expression of stromal cell–derived factor-1α (SDF-1α)/CXC chemokine receptor 4 (CXCR4) in human dental pulp and the SDF-1α–CXCR4 axis might play a role in the recruitment of CXCR4-positive dental pulp cells (CXCR4+ DPCs) toward the damaged sites. However, the specific function of CXCR4+ DPCs in the injured dental pulp was still unknown. The purpose of this study was to isolate CXCR4+ DPCs from dental pulp cells in vitro to pave the way for further study of their characteristics. MethodsCXCR4+ DPCs were isolated with magnetic-activated cell sorting (MACS). Freshly isolated CXCR4+ DPCs were identified by immunohistochemistry with light microscopy or confocal microscopy. Then the phenotypes CXCR4, stromal cell surface marker-1 (STRO-1), CD146, and CD34 in 3 groups (ie, CXCR4+ DPCs, CXCR4− DPCs, or non-sorted DPCs) were analyzed by flow cytometry after they were cultured and expanded in vitro. ResultsThe results indicated the isolated subpopulation of DPCs was enriched with CXCR4+ DPCs, and the positive rates of STRO-1 and CD146 in CXCR4+ DPCs group were higher than CXCR4− DPCs or non-sorted DPCs groups (P < .05). There was no expression of CD34 in each group. ConclusionsWe can isolate CXCR4+ DPCs from DPCs with MACS and identify them by immunohistochemistry and flow cytometry.

Transmyocardial drilling revascularization combined with heparinized bFGF-incorporating stent activates resident cardiac stem cells via SDF-1/CXCR4 axis

Objective To investigate whether transmyocardial drilling revascularization combined with heparinized basic fibroblast growth factor (bFGF)-incorporating degradable stent implantation (TMDRSI) can promote myocardial regeneration after acute myocardial infarction (AMI). Methods A model of AMI was generated by ligating the mid-third of left anterior descending artery (LAD) of miniswine. After 6 h, the animals were divided into none-treatment (control) group (n = 6) and TMDRSI group (n = 6). For TMDRSI group, two channels with 3.5 mm in diameter were established by a self-made drill in the AMI region, into which a stent was implanted. Expression of stromal cell-derived factor-1 α ( SDF-1 α ) and CXC chemokine receptor 4 ( CXCR4), cardiac stem cell (CSC)-mediated myocardial regeneration, myocardial apoptosis, myocardial viability, and cardiac function were assessed at various time-points. Results Six weeks after the operation, CSCs were found to have differentiated into cardiomyocytes to repair the infarcted myocardium, and all above indices showed much improvement in the TMDRSI group compared with the control group ( P < 0.001). Conclusions The new method has shown to be capable of promoting CSCs proliferation and differentiation into cardiomyocytes through activating the SDF-1/ CXCR4 axis, while inhibiting myocardial apoptosis, thereby enhancing myocardial regeneration following AMI and improving cardiac function. This may provide a new strategy for myocardial regeneration following AMI.

Exogenous basic fibroblast growth factor promotes cardiac stem cell-mediated myocardial regeneration after miniswine acute myocardial infarction

To investigate the effects of exogenous basic fibroblast growth factor (bFGF) on myocardial regeneration after acute myocardial infarction (AMI). AMI models were established by ligating the mid-third of left anterior descending artery, thereafter, miniswines were randomly divided into control (none treatment, n = 6) and bFGF groups (n = 6). For the bFGF group, bFGF (100 μg) was injected with a sterile microinjection at five sites within the ischemic region. 5-Bromo-2-deoxyuridine (250 mg) was administrated intravenously twice a week after the operation, to label cells undergoing DNA replication. The expression of stromal cell-derived factor-1α (SDF-1α) and CXC chemokine receptor 4 (CXCR4), cardiac stem cell-mediated myocardial regeneration, myocardial apoptosis, histological and immunohistochemical analyses, and cardiac function were evaluated at different time points. Four weeks after bFGF therapy, it showed an increased vessel density and myocardial perfusion (P < 0.001), upregulative expression of SDF-1α and CXCR4 (P < 0.001), increased c-kit and 5-bromo-2-deoxyuridine-positive cells (P < 0.001), enhanced myocardial viability (P < 0.001), and improved left ventricular ejection fraction (P = 0.007), compared with the control. Exogenous bFGF was shown to have increased angiogenesis and myocardial perfusion, promoted myocardial regeneration by activating the SDF-1α/CXCR4 axis, and thereby improved the cardiac function, which may provide a new therapeutic strategy for AMI.

The omentum is a site of stromal cell–derived factor 1α production and reservoir for CXC chemokine receptor 4–positive cell recruitment

Background The mechanism of the omental response to injury remains poorly defined. This study investigates the omental reaction to a foreign body, examining the role of a chemokine ligand/receptor pair known to play a crucial role in angiogenesis and wound healing. Methods A ventral hernia, surgically created in the abdominal wall of 6 swine, was repaired with silicone sheeting to activate the omentum. Omental thickness was determined by ultrasonography. Serial stromal cell–derived factor 1α (SDF-1α) concentrations were measured in blood, wound, and peritoneal fluids by enzyme-linked immunosorbent assay. Results During the 14-day study period, serial ultrasonography showed a 20-fold increase in omental thickness, and enzyme-linked immunosorbent assay revealed a 4-fold increase in SDF-1α concentration in local wound fluid. Omental vessel count and vascular surface area were 8- to 10-fold higher in reactive omentum. Immunohistochemistry showed nearly complete replacement of control omental fat with CXC chemokine receptor 4 (CXCR4)-positive cells by day 14. Conclusions Activated omentum, important in the SDF-1α/CXCR4 axis, may serve as an intraperitoneal reservoir for recruitment of circulating bone marrow–derived cells vital to healing.

Inhibitory effect of CXC chemokine receptor 4 antagonist AMD3100 on bleomycin induced murine pulmonary fibrosis

CXC chemokine receptor 4 (CXCR4), which binds the stromal cell-derived factor-1 (SDF-1), has been shown to play a critical role in mobilizing the bone marrow (BM)-derived stem cells and inflammatory cells. We studied the effects of AMD3100, CXCR4 antagonist, on a murine bleomycin-induced pulmonary fibrosis model. Treatment of mice with AMD3100 in bleomycin-treated mice resulted in the decrease of SDF-1 in bronchoalveolar lavage (BAL) fluids at an early stage and was followed by the decrease of fibrocytes in the lung. AMD3100 treatment decreased the SDF-1 mRNA expression, fibrocyte numbers in the lung at an early stage (day 3) and CXCR4 expression at the later stage (day 7 and 21) after bleomycin injury. The collagen content and pulmonary fibrosis were significantly attenuated by AMD3100 treatment in later stage of bleomycin injury. AMD3100 treatment also decreased the murine mesenchymal and hematopoietic stem cell chemotaxis when either in the stimulation with bleomycin treated lung lysates or SDF-1 in vitro. In BM stem cell experiments, the phosphorylation of p38 MAPK which was induced by SDF-1 was significantly blocked by addition of AMD3100. Our data suggest that AMD3100 might be effective in preventing the pulmonary fibrosis by inhibiting the fibrocyte mobilization to the injured lung via blocking the SDF-1/CXCR4 axis.

The role of SDF-1/CXCR4 axis in ovarian cancer metastasis

This study was aimed to explore the role of stromal-derived factor 1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) axis in mediating the metastasis of ovarian cancer cells through activation of extracellular signal-regulated kinase-1/2 (ERK-1/2) signaling pathway. A highly metastatic ovarian cancer cell line, SKOV3, was used in the study. Intracellular calcium mobilization was detected by using laser scanning confocal fluorescence microscopy. Western blotting was used to detect the phosphorylation of ERK1/2 in SDF-1alpha-treated SKOV3 cells. Adhesion capability and matrix metalloproteinase (MMP) activity of ovarian cancer cells after exposure to SDF-1alpha were measured by adhesion assay and gelatin zymography. The results showed that SDF-1alpha induced rapid intracellular calcium mobilization in SKOV3 cells, as well as the phosphorylation of ERK-1/2. The adhesion of ovarian cancer cells to fibronectin and collagen IV was increased after SDF-1alpha treatment. An inhibitor of ERK-1/2 signaling, PD98059, could antagonize such effects of SDF-1alpha. SDF-1alpha could also increase the secretion of active MMP-2 and MMP-9. It was concluded that the SDF-1/CXCR4 axis played a critical role in the metastasis of human ovarian cancer by increasing the adhesion capability of cancer cells and the activity of MMP-2 and MMP-9 via ERK1/2 signaling pathway.

Inhibition of the SDF-1/CXCR4 Axis Attenuates Neonatal Hypoxia-Induced Pulmonary Hypertension

Exposure of the neonatal lung to chronic hypoxia produces significant pulmonary vascular remodeling, right ventricular hypertrophy, and decreased lung alveolarization. Given recent data suggesting that stem cells could contribute to pulmonary vascular remodeling and right ventricular hypertrophy, we tested the hypothesis that blockade of SDF-1 (stromal cell-derived factor 1), a key stem cell mobilizer or its receptor, CXCR4 (CXC chemokine receptor 4), would attenuate and reverse hypoxia-induced cardiopulmonary remodeling in newborn mice. Neonatal mice exposed to normoxia or hypoxia were randomly assigned to receive daily intraperitoneal injections of normal saline, AMD3100, or anti-SDF-1 antibody from postnatal day 1 to 7 (preventive strategy) or postnatal day 7 to 14 (therapeutic strategy). As compared to normal saline, inhibition of the SDF-1/CXCR4 axis significantly improved lung alveolarization and decreased pulmonary hypertension, right ventricular hypertrophy, vascular remodeling, vascular cell proliferation, and lung or right ventricular stem cell expressions to near baseline values. We therefore conclude that the SDF-1/CXCR4 axis both prevents and reverses hypoxia-induced cardiopulmonary remodeling in neonatal mice, by decreasing progenitor cell recruitment to the pulmonary vasculature, as well as by decreasing pulmonary vascular cell proliferation. These data offer novel insights into the role of the SDF-1/CXCR4 axis in the pathogenesis of neonatal hypoxia-induced cardiopulmonary remodeling and have important therapeutic implications.

Stromal cell-derived factor-1/CXC chemokine receptor-4 axis and hepatic stem cell transplantation

基质细胞衍生因子-1（stromal cell-derived factor-1,SDF-1）及其受体CXCR4构成SDF-1/CXCR4轴体系统.近年来随着该领域科研的不断深入,越来越多的研究发现SDF-1/CXCR4轴体系统在组织损伤及修复中起着重要的作用.本文主要对SDF-1/CXCR4轴体系统的生物学特性及其在肝脏干细胞移植中的作用进行综述.

Decreased Vascular Repair and Neovascularization with Ageing: Mechanisms and Clinical Relevance with an Emphasis on Hypoxia- Inducible Factor-1

Ageing is associated with endothelial dysfunction, decreased endothelial progenitor cell (EPC) function and mobilization. These defects culminate in a decreased capacity for neovascularization in the aged. Multiple lines of evidence suggest that defective neovascularization with ageing is related to depressed signaling by hypoxia inducible factor-1 (HIF-1). HIF-1, the master regulator or neovascularization, regulates the expression of vascular endothelial growth factor (VEGF), stromal cell-derived factor-1 (SDF-1) and CXC chemokine Receptor-4 (CXCR4). Given that the SDF-1/CXCR4 axis is a crucial regulator of progenitor cell function and homing, the ramifications of depressed HIF-1 signaling with age include depressed vascular repair, neovascularization and wound healing. We review the literature showing the depression of these processes with age and discuss the relevance of these findings to several clinical contexts. Further, the effects of age on EPC number, function and mobilization are related to the age-related decline in HIF-1 signaling. We suggest that exercise, Cobalt compounds or hydralazine may reverse the age-related decline by up-regulating HIF-1-mediated signaling.