Effects of statins on endothelium and their contribution to neovascularization by mobilization of endothelial progenitor cells

Statins are potent drugs with a variety of cardiovascular protective effects which appear to occur independent of cholesterol reduction. The vasculoprotective effects of statins might be due to their direct effect on endothelial cells leading to improved nitric oxide (NO) bioavailability. Mechanistically, statins induce endothelial nitric oxide synthesis (eNOS) mRNA stability in endothelial cells and promote eNOS activity through a PI3K/Akt dependent pathway. Novel targets of statins are pro-angiogenic actions including the mobilization and differentiation of bone marrow derived endothelial progenitor cells, which accelerate angiogenesis or re-endothelialization. The functional improvement and increased homing capacity of endothelial progenitor cells induced by statin treatment might reverse impaired functional regeneration capacities seen in patients with risk factors for coronary artery disease or documented active coronary artery disease.     

氟伐他汀动员内皮祖细胞促进大鼠梗死心肌血管新生的作用

目的观察氟伐他汀动员急性心肌梗死（AMI）大鼠内皮祖细胞（EPCs）,促进梗死心肌血管新生,减小梗死面积的效果。方法①成年Wistar大鼠左前降支结扎造模,随机分为空白组（A组）、假手术组（B组）、AMI组（C组）和氟伐他汀治疗AMI组（D组）。②流式细胞技术检测不同时段大鼠外周静脉血EPC动态变化。③4周末处死大鼠,心肌切片Masson染色,左室心肌正中线弧长方法计算梗死面积。④CD31单克隆抗体免疫组化法标记心肌新生血管内皮细胞并计算各组梗死、梗死周边及非梗死区新生血管数。结果①造模后第7天D组EPCs（37．13±3．44／2×10^5MNCs）显著高于A组（19．88±4．91／2×10^5MNCs）、B组（22．33±5．43／2×10^5MNCs）和C组（26．56±3．17／2×10^5MNCs）,差异具有统计学意义（P〈0．05）;C组较A组有少量增加（P〈0．05）,B组较A组无明显升高（P〉0．05）,B组和c组差异无统计学意义（P〉0．05）。造模后第14天D组EPCs（45．5-±4．99／2×10^5MNCs）同样显著高于A组（17．25±7．17／2×10^5MNCs）、B组（22．78±2．91／2×10^5MNCs）和C组（26．88±3．76／2×10^5MNCs）（P〈0．05）;B组和C组较A组有少量增加（P〈0．05）,B组和C组差异无统计学意义（P〉0．05）。第7天和第14天各组变化比较,A、B、C三组EPCs变化无统计学意义（P〉0．05）,D组则明显增加（P〈0．05）。②D组梗死区新生血管计数（10．75±1．61／mm。）明显多于C组（5．09±2．33／mm。）（P〈0．01）,梗死周边区新生血管计数D组（17．53±2．35／mm^2）同样明显多于C组（8．55±2．40／mm^2）（P〈0．01）。③D组梗死面积[（31．41±2．59）％]小于C组[（35．67±5．22）％]（P〈0．01）。结论①氟伐他汀能动员急性心肌梗死大鼠内皮祖细胞进入外周血循环,使其数量增加并促进梗死周边区血管新生。②心肌梗死后大鼠应用氟伐他汀可以限制梗死面积。     

Haeme oxygenase promotes progenitor cell mobilization, neovascularization, and functional recovery after critical hindlimb ischaemia in mice

AIMS: Neovascularization is an important element of long-term functional recovery during chronic ischaemia. We postulated that haeme oxygenase (HO) is required for progenitor cell recruitment, neovascularization, and blood flow recovery after critical hindlimb ischaemia (HLI). METHODS AND RESULTS: The femoral artery was ligated in FVB/N mice proximal to its superficial and deep branches. Blood flow in the ischaemic hindlimb was determined by laser Doppler perfusion imaging. Capillary density was measured by isolectin staining, and mobilization of Sca-1(+)/Kdr(+) progenitor cells by FACS analysis. Progenitor cell recruitment to the ischaemic hindlimb was assessed after Tie2-lacZ transgenic bone marrow transplantation. Blood flow recovery after femoral artery ligation was significantly blunted in mice treated with the HO inhibitor tin protoporphyrin-IX (25 mg/kg i.p., every other day). HO-inhibited mice developed more pronounced limb necrosis, associated with impaired hindlimb motor function. Capillary density in the ischaemic hindlimb and mobilization of Sca-1(+)/Kdr(+) progenitor cells were significantly reduced after HO inhibition. After transplantation of Tie2-lacZ transgenic bone marrow cells into lethally irradiated wild-type mice, fewer LacZ(+) cells were detected in the ischaemic hindlimb muscle of HO-inhibited mice. Mechanistically, HO inhibition prevented the establishment of a stromal cell-derived factor-1 gradient for progenitor cell mobilization between the ischaemic hindlimb and bone marrow. CONCLUSION: HOs are required for progenitor cell recruitment, neovascularization, and functional recovery after HLI.     

Leptin enhances the recruitment of endothelial progenitor cells into neointimal lesions after vascular injury by promoting integrin-mediated adhesion

The adipocytokine leptin modulates vascular remodeling and neointima formation. Because endothelial progenitor cells (EPCs) participate in vascular repair, we analyzed the effects of leptin on human EPC function in vitro and in vivo. After 7 days in culture, EPCs expressed the leptin receptor and responded to leptin stimulation with increased STAT3 phosphorylation. Incubation of EPCs with leptin (at concentrations between 1 and 100 ng/mL) increased the number of EPCs adhering to vitronectin and fibronectin in a receptor-specific manner. It also enhanced the capacity of EPCs to incorporate into a monolayer of human endothelial cells and the adherence of these cells to activated platelets. Leptin upregulated alphavbeta5 and alpha4 integrin expression in EPCs, and the effects of leptin on EPC function could be prevented, at least in part, by RGD peptides and function-blocking antibodies. Intravenous injection of fluorescently labeled human EPCs into athymic nude mice shortly after vascular injury revealed that preincubation of EPCs with leptin augmented their accumulation within intimal lesions, accelerating reendothelialization and decreasing neointima formation in an alphavbeta5 and alpha4 integrin-dependent manner. Our findings suggest that leptin specifically modulates the adhesive properties and the homing potential of EPCs and may thus enhance their capacity to promote vascular regeneration in vivo.     

Protection against vascular aging in Nox2-deficient mice: Impact on endothelial progenitor cells and reparative neovascularization

BackgroundAging is associated with increased oxidative stress levels and impaired neovascularization following ischemia. Because Nox2-containing NADPH oxidase is a major source of ROS in the vasculature, we investigated its potential role for the modulation of ischemia-induced neovascularization in the context of aging.Methods and resultsHindlimb ischemia was surgically induced by femoral artery removal in young (2 months) and old (10 months) Nox2-deficient (Nox2^?/?) and wild type mice. We found that Nox2 expression is increased by aging in ischemic muscles of wild type mice. This is associated with a significant reduction of blood flow recovery after ischemia in old compared to young mice at day 21 after surgery (Doppler flow ratios: 0.51 ± 0.05 vs. 0.72 ± 0.05; p < 0.05). We also demonstrate that capillary and arteriolar densities are significantly reduced in ischemic muscles of old animals, while oxidative stress levels are increased (nitrotyrosine immunostaining). Importantly, Nox2 deficiency reduces oxidative stress levels in ischemic tissues and restores blood flow recuperation and vascular densities in old animals. Endothelial progenitor cells (EPCs) have an important role for postnatal neovascularization. Here we show that the functional activities of EPCs (migration, adhesion to mature endothelial cells) are significantly impaired in old compared to young mice. However, Nox2 deficiency rescues EPC functional activities in old animals. We also demonstrate an age-dependent pathological increase of oxidative stress levels in EPCs (DHE, DCF-DA) that is not present in Nox2-deficient animals.ConclusionNox2-containing NADPH oxidase deficiency protects against age-dependent impairment of neovascularization. Potential mechanisms include reduced ROS generation in ischemic tissues and preserved angiogenic activities of EPCs.     

内皮祖细胞的动员及影响因素

内皮祖细胞是一类能分化成血管内皮细胞的前体细胞，在生后成人血管发生（vaseulogenesis）中起着重要的作用。从骨髓刺激内皮祖细胞的动员，增加循环内皮祖细胞的数量，是促进血管新生（neovascularization）的一种有效措施，因此对动员影响因素及其机制的研究具有重要临床意义。     

S1P promotes murine progenitor cell egress and mobilization via S1P1-mediated ROS signaling and SDF-1 release

The mechanisms of hematopoietic progenitor cell egress and clinical mobilization are not fully understood. Herein, we report that in vivo desensitization of Sphingosine-1-phosphate (S1P) receptors by FTY720 as well as disruption of S1P gradient toward the blood, reduced steady state egress of immature progenitors and primitive Sca-1(+)/c-Kit(+)/Lin(-) (SKL) cells via inhibition of SDF-1 release. Administration of AMD3100 or G-CSF to mice with deficiencies in either S1P production or its receptor S1P(1), or pretreated with FTY720, also resulted in reduced stem and progenitor cell mobilization. Mice injected with AMD3100 or G-CSF demonstrated transient increased S1P levels in the blood mediated via mTOR signaling, as well as an elevated rate of immature c-Kit(+)/Lin(-) cells expressing surface S1P(1) in the bone marrow (BM). Importantly, we found that S1P induced SDF-1 secretion from BM stromal cells including Nestin(+) mesenchymal stem cells via reactive oxygen species (ROS) signaling. Moreover, elevated ROS production by hematopoietic progenitor cells is also regulated by S1P. Our findings reveal that the S1P/S1P(1) axis regulates progenitor cell egress and mobilization via activation of ROS signaling on both hematopoietic progenitors and BM stromal cells, and SDF-1 release. The dynamic cross-talk between S1P and SDF-1 integrates BM stromal cells and hematopoeitic progenitor cell motility.     

Circulating endothelial (progenitor) cells reflect the state of the endothelium: vascular injury, repair and neovascularization

An increase in the number of circulating endothelial cells (CEC) and of bone marrow-derived endothelial progenitor cells (EPC) in the peripheral blood is associated with vascular injury, repair and neovascularization. The phenotype and number of CEC may serve as diagnostic or prognostic parameters of vascular injury and tumour growth. An increase in the number of EPC may reflect repair of ischaemic vascular injury, a finding which has resulted in the initiation of clinical cardiovascular pilot trials using cell therapy. However, there is no consensus on the exact phenotype of the EPC and haematopoietic stem cells (HSC) and therefore the best candidate cell for transplant has not been established. Although the use of peripheral blood stem cells following mobilization, or of ex vivo-expanded cells, may improve EPC-mediated vascular graft endothelialization or tissue vascularization, sustained EPC-induced neovascularization still needs to be proven. Flow cytometric characterization, in combination with functional assays, will further elucidate the phenotype of the CEC and EPC, thereby providing reliable detection to appreciate their role in vascular diseases and cancer and to evaluate and, if possible, improve their therapeutic potential.     

去除穿膜区序列的线粒体融合素2基因通过线粒体凋亡路径促进大鼠血管平滑肌细胞凋亡

目的 研究去除穿膜区序列的大鼠线粒体融合素2(tMfn2)基因对大鼠血管平滑肌细胞(VSMC)凋亡的影响及其相关的信号通路.方法 用携带tMfn2基因和线粒体融合素2(Mfn2)基因的重组腺病毒(Adv-tMfn2和Adv-Mfn2)感染VSMC.采用流式细胞术、细胞凋亡ELISA、TUNEL染色等方法检测tMfn2对VSMC凋亡的影响.Western blot分析磷酸化蛋白激酶B(p-Akt)以及线粒体凋亡路径中B细胞淋巴瘤/白血病-2蛋白(Bcl-2)、Bcl-2相关的X蛋白(Bax)、有活性的天冬氨酸特异-半胱氨酸蛋白酶9(cleaved caspase-9)的表达变化.结果 流式细胞仪检测和ELISA结果表明.tMfn2促VSMC凋亡的作用显著强于Mfn2,且呈时间依赖性[72 h凋亡率分别为(79.2±0.12)%和(65.0±1.2)%,P<0.01].TUNEL染色发现tMfn2组的凋亡细胞明显多于Mfn2组(P<0.01).Western blot结果显示,tMfn2和Mfn2组中p-Akt水平均明显降低,但前者作用更显著(P<0.01).进一步检测线粒体凋亡路径中的相关蛋白,tMfn2组的Bax蛋白表达显著升高、Bcl-2蛋白表达显著降低,且cleaved caspase-9的活性明显增强,较Mfn2诱导凋亡的作用更强(P<0.01).结论 与Mfn2相比,tMfn2促进VSMC凋亡的作用更强,其机制与抑制Akt磷酸化并激活线粒体凋亡途径有关.     

缬沙坦对压力超负荷兔心肌基质金属蛋白酶表达及胶原重构的影响

目的:观察缬沙坦对慢性压力超负荷兔左室肌基质金属蛋白酶-2,9(MMP2、MMP9)表达及胶原网络重构的影响,并探讨其机制。方法:36只家兔随机分为假手术组(12只)、结扎组(12只)、缬沙坦组(12只),腹主动脉次全结扎制备压力超负荷家兔模型。缬沙坦组给予缬沙坦(30mg·kg-1·d-1)灌胃,假手术组、结扎组给予等量的蒸馏水。术后12周取兔心肌行VG染色及免疫组化染色,观察胶原容积百分比(CVF)及MMP2、MMP9表达情况。结果:假手术组、结扎组、缬沙坦组MMP2的表达灰度值分别是(70.7±8.4)、(143.6±10.5)、(99.7±9.6),MMP9分别是(68.4±7.1)、(128.4±8.7)、(87.4±11.2);含小血管的CVF分别是(8.15±0.91)%、(17.72±0.64)%、(13.06±0.89)%。结论:基质金属蛋白酶是促使慢性压力超负荷下心肌胶原网络重构的重要因素,缬沙坦通过抑制基质金属蛋白酶能够改善胶原重构。     

Effect of CCN2 on FGF2-induced proliferation and MMP9 and MMP13 productions by chondrocytes

CCN2 (also known as connective tissue growth factor) interacts with several growth factors involved in endochondral ossification via its characteristic four modules and modifies the effect of such growth factors. Presently we investigated whether CCN2 interacts with fibroblast growth factor 2 (FGF2). Solid-phase binding assay, immunoprecipitation-Western blot analysis, and surface plasmon resonance (SPR) spectroscopy revealed that the C-terminal module of CCN2 (CT) directly bound to FGF2 with a dissociation constant of 5.5 nm. Next, we examined the combinational effects of CCN2 and FGF2 on the proliferation of and matrix metalloproteinase (MMP)-9 and -13 productions by cultured chondrocytes. FGF2 promoted not only the proliferation but also the production of MMP9 and -13, however, combined of FGF2 with CT module nullified the enhancement of both MMP productions and proliferation. To clarify the mechanism, we investigated the binding of CCN2 or its CT module to FGF receptor 1. As a result, we found that CCN2 bound to FGF receptor 1 with a dissociation constant of 362 nm, whereas the CT module did not. In addition, when we tested FGF signaling in chondrocytic HCS-2/8 cells stimulated by the combination of FGF2 with CT module, the level of ERK1/2, p38 MAPK, and c-Jun N-terminal kinase phosphorylation was decreased compared with that found with FGF2 alone. These findings suggest that CCN2 may regulate the proliferation and matrix degradation of chondrocytes by forming a complex with FGF2 as a novel modulator of FGF2 functions.     

Effective contribution of transplanted vascular progenitor cells derived from embryonic stem cells to adult neovascularization in proper differentiation stage

We demonstrated that Flk-1⁺ cells derived frommouse embryonic stem (ES) cells can differentiate into both endothelialcells (ECs) and mural cells (MCs) to suffice as vascular progenitor cells (VPCs). In the present study, we investigated the importance ofthe stage of ES cell differentiation on effective participation inadult neovascularization. We obtained Flk-1⁺LacZ-expressing undifferentiated VPCs. Additional culture of these VPCswith vascular endothelial growth factor (VEGF) resulted in a mixture ofECs and MCs (differentiated VPCs). We injected VPCs subcutaneously intotumor-bearing mice. Five days after the injection, whereasundifferentiated VPCs were often detected as nonvascular cells,differentiated VPCs were more specifically incorporated into developingvasculature mainly as ECs. VPC-derived MCs were also detected invascular walls. Furthermore, transplantation of differentiated VPCsaugmented tumor blood flow in nude mice. These results indicate that aspecific vascular contribution in adult neovascularization can beachieved by selective transplantation of ES cell-derived VPCs inappropriate differentiation stages, which should be the basis forvascular regeneration schemes.     

高糖对系膜细胞金属蛋白酶表达的影响及肝素的干预作用

目的:研究高糖对正常人类系膜细胞(NHMc)增殖及金属蛋白酶2(MMP2)和金属蛋白酶9(MMP9)表达的影响及肝素对其的干预作用.方法:NHMC在含和(或)不含肝素的高糖培养基中培养,以正常糖培养基作对照.采用WST-1法测定NHMC增殖状况;用Western Blot技术分析MMP2、MMP9表达情况.结果:高糖组NHMC增殖明显高于对照组,二组间有显著性差异(P＜0.05).用肝素干预后,高糖组肝素浓度为50μg/ml时,NHMC增殖开始受到抑制,且随着肝素浓度递增,NHMC增殖抑制更明显(肝素50～400μg/ml浓度组与未加肝素组比较,均P＜0.05或P＜0.01).而对照组肝素浓度为200μg/ml时,NHMC增殖才出现抑制(肝素200～400μg/ml组与未加肝素组比较,均P＜0.05).另外,高糖与对照组NHMC均有一定量MMP2、MMP9表达,加入肝素后MMP2、MMP9出现高表达,特别是在高糖组尤为明显.结论:肝素能抑制高糖刺激下NHMC增殖并能使体外NHMC中的MMP2、MMP9出现高表达,推测MMPs可能参与了高糖状态下NHMC的细胞外基质的降解过程并且肝素有肾保护作用.     

Neutrophil-derived MMP-9 mediates synergistic mobilization of hematopoietic stem and progenitor cells by the combination of G-CSF and the chemokines GRObeta/CXCL2 and GRObetaT/CXCL2delta4

Mobilized peripheral blood stem cells (PBSCs) are widely used for transplantation, but mechanisms mediating their release from marrow are poorly understood. We previously demonstrated that the chemokines GRObeta/CXCL2 and GRObetaT/CXCL2Delta4 rapidly mobilize PBSC equivalent to granulocyte colony-stimulating factor (G-CSF) and are synergistic with G-CSF. We now show that mobilization by GRObeta/GRObetaT and G-CSF, alone or in combination, requires polymorphonuclear neutrophil (PMN)-derived proteases. Mobilization induced by GRObeta/GRObetaT is associated with elevated levels of plasma and marrow matrix metalloproteinase 9 (MMP-9) and mobilization and MMP-9 are absent in neutrophil-depleted mice. G-CSF mobilization correlates with elevated neutrophil elastase (NE), cathepsin G (CG), and MMP-9 levels within marrow and is partially blocked by either anti-MMP-9 or the NE inhibitor MeOSuc-Ala-Ala-Pro-Val-CMK. Mobilization and protease accumulation are absent in neutrophil-depleted mice. Synergistic PBSC mobilization observed when G-CSF and GRObeta/GRObetaT are combined correlates with a synergistic rise in the level of plasma MMP-9, reduction in marrow NE, CG, and MMP-9 levels, and a coincident increase in peripheral blood PMNs but decrease in marrow PMNs compared to G-CSF. Synergistic mobilization is completely blocked by anti-MMP-9 but not MeOSuc-Ala-Ala-Pro-Val-CMK and absent in MMP-9-deficient or PMN-depleted mice. Our results indicate that PMNs are a common target for G-CSF and GRObeta/GRObetaT-mediated PBSC mobilization and, importantly, that synergistic mobilization by G-CSF plus GRObeta/GRObetaT is mediated by PMN-derived plasma MMP-9.     

Cytomegalovirus MCK-2 controls mobilization and recruitment of myeloid progenitor cells to facilitate dissemination

Murine cytomegalovirus encodes a secreted, pro-inflammatory chemokine-like protein, MCK-2, that recruits leukocytes and facilitates viral dissemination. We have shown that MCK-2-enhanced recruitment of myelomonocytic leukocytes with an immature phenotype occurs early during infection and is associated with efficient viral dissemination. Expression of MCK-2 drives the mobilization of a population of leukocytes from bone marrow that express myeloid marker Mac-1 (CD11b), intermediate levels of Gr-1 (Ly6 G/C), platelet-endothelial-cell adhesion molecule-1 (PECAM-1, CD31), together with heterogeneous levels of stem-cell antigen-1 (Sca-1, Ly-6 A /E). Recombinant MCK-2 mediates recruitment of this population even in the absence of viral infection. Recruitment of this cell population and viral dissemination via the bloodstream to salivary glands proceeds normally in mice that lack CCR2 and MCP-1 (CCL2), suggesting that recruitment of macrophages is not a requisite component of pathogenesis. Thus, a systemic impact of MCK-2 enhances the normal host response and causes a marked increase in myelomonocytic recruitment with an immature phenotype to initial sites of infection. Mobilization influences levels of virus dissemination via the bloodstream to salivary glands and is dependent on a myelomonocytic cell type other than mature macrophages.     

基质金属蛋白酶2/9介导的CD100剪切释放在介导肝内抗-HBV CD8 T淋巴细胞应答和HBV清除过程中发挥关键作用

【据《J Hepatol》2019 年10 月报道】题:基质金属蛋白酶2 /9 介导的CD100 剪切释放在介导肝内抗- HBV CD8 T淋巴细胞应答和HBV 清除过程中发挥关键作用(作者Yang S 等)CD100 在T 淋巴细胞上组成性表达,并且可被基质金属蛋白酶(MMP)剪切从细胞膜表面释放,形成可溶性CD100(sCD100)。