Norrin基因对人视网膜微血管内皮细胞增殖和周期的影响

目的：体外培养并鉴定人视网膜微血管内皮细胞（HRCECs），并探讨Norrin基因高表达对HRCECs增殖和周期的影响。方法： 体外分离、培养并鉴定人视网膜微血管内皮细胞，抗第Ⅷ因子相关抗原抗体鉴定细胞。利用脂质体lipofectamine 2000将AP-3myc-hNorrin/pRK5质粒转染HRCECs，RT-PCR、免疫组化和Western blotting方法检测Norrin/myc的表达确定转染效率。采用MTT法测定转染后细胞的增殖能力，流式细胞术分析其细胞周期变化。结果： 所培养的细胞第Ⅷ因子相关抗原免疫组化为强阳性。AP-3myc-hNorrin/pRK5质粒转染后 24 h，RT-PCR显示实验组Norrin表达水平明显高于阴性对照组(P<0.01)。转染后48h免疫组化及Western blotting均显示实验组细胞Myc表达强于阴性对照组。MTT法显示细胞增殖高于对照组，细胞周期检测示实验组G2期细胞高于阴性对照组，P<0.01。结论：脂质体能成功转染AP-3myc-hNorrin/pRK5进入HRCECs。Norrin高表达能促进HRCECs的增殖，并促进细胞DNA合成，提示Norrin在视网膜血管生成过程中可能具有重要作用。     

Diabetic retinopathy: mitochondrial dysfunction and retinal capillary cell death

Oxidative stress is increased in the retina in diabetes; the levels of oxidatively modified DNA and nitrosylated proteins are elevated, and antioxidant defense enzymes are impaired. The levels of superoxides are elevated in the retina, and the mitochondria become dysfunctional with proapoptotic protein, Bax, translocating from the cytosol into the mitochondria, and cytochrome c leaking out from the mitochondria. This is accompanied by increased retinal capillary cell apoptosis, and the formation of acellular capillaries and pericyte ghosts, the early signs of retinopathy in animal models of diabetic retinopathy. Inhibition of superoxides inhibits glucose -induced mitochondrial dysfunction, activation of caspase-3, and cell death in retinal capillary cells. In animal models, long-term administration of lipoic acid or other antioxidants inhibits the development of diabetic retinopathy via inhibition of accumulation of oxidatively modified DNA and nitrotyrosine and capillary cell apoptosis in the retina. Understanding the role of mitochondria in the development of retinopathy in diabetes should help identify therapies that can neutralize superoxides and inhibit their dysfunction and, ultimately, the development of retinopathy.     

Rare glomerular capillary regeneration and subsequent capillary regression with endothelial cell apoptosis in progressive glomerulonephritis.

Glomerulonephritis (GN) leading to glomerular sclerosis remains an important cause of renal failure. The glomerulus is a capillary network, but endothelial and vascular reactions during progressive GN are not well understood. We have, therefore, examined the morphological alterations of glomerular capillary network and endothelial cells during the progression of damaged glomeruli to glomerular sclerosis. A progressive model of anti-glomerular basement membrane (GBM) GN was induced in Wistar-Kyoto (WKY) rats with a single injection of anti-rat GBM antibody. Severe necrotizing glomerular injuries were observed between day 5 and week 3 with a reduction in the number of total glomerular endothelial cells and total glomerular capillary lumina per glomerular cross sections. In necrotizing lesions, the glomerular endothelial cells were lost with the destruction of the glomerular capillary network. Moreover, angiogenic capillary repair with proliferation of endothelial cells was rare in severely damaged regions of glomeruli. Subsequently, mesangial hypercellularity and marked mesangial matrix accumulation occurred with absence of the development of a capillary network, and the necrotizing lesions progressed to sclerotic scars until 8 weeks. Although active necrotizing lesions could not be seen in damaged glomeruli between week 4 and week 8, the number of apoptotic endothelial cells gradually increased in the glomerular capillaries (0.10 +/- 0.01 apoptotic endothelial cells/glomerular cross section at week 8 versus 0.00 +/- 0.00 control cells (mean +/- SEM; P < 0.05) with the progression of glomerular sclerosis. Whereas the number of apoptotic endothelial cells increased in the damaged glomeruli, the number of total glomerular endothelial cells decreased (9.3 +/- 3.0 cells/glomerular cross section at week 8 versus 24.8 +/- 3.0 cells in control (mean +/- SD); P < 0.001) with regression of glomerular capillaries (3.6 +/- 2.5 capillary lumina/glomerular cross section at week 8 versus 35.0 +/- 5.0 capillary lumina in control (mean +/- SD); P < 0.001). Finally, glomerular endothelial cells could not be detected in the sclerotic lesions in progressive anti-GBM GN in WKY rats. These data indicate that the destruction of the capillary network of glomeruli and subsequent incomplete angiogenic capillary repair leads to glomerular sclerosis in progressive GN. Endothelial cell apoptosis with glomerular capillary regression may also contribute to the development of glomerular sclerosis. Injury of the glomerular capillary network with endothelial cell damage, including apoptosis and subsequent incomplete capillary repair, plays an important role in the progression of glomerular sclerosis during anti-GBM GN in WKY rats.     

Interactions between lymphocytes and cells of the blood-retina barrier: mechanisms of T lymphocyte adhesion to human retinal capillary endothelial cells and retinal pigment epithelial cells in vitro

We have studied the adhesion of human CD4+ lymphocytes to cultured human retinal vascular endothelial cells (EC) and human retinal pigment epithelial cells (RPE), both of which comprise the cellular components of the blood-retina barrier. We have observed differences in the lymphocyte-RPE and the lymphocyte-EC interactions. Firstly, RPE cells were found to express high levels of the adhesion molecule ICAM-1 constitutively, whereas EC expressed ICAM-1 only after induction with IFN-gamma. In addition, lymphocyte binding to normal and minimally stimulated RPE (5 U/ml, 4 hr) was predominantly ICAM-1 dependent, but after maximal stimulation (500 U/ml, 4 days), increased lymphocyte adhesiveness included an ICAM-1-independent component, which was apparently not due to involvement of MHC class II or CD2 molecules. In contrast, binding of lymphocytes to unstimulated EC involved both an ICAM-1-dependent and an ICAM-1-independent mechanism, the latter being subject to inhibition by monoclonal antibody to CD2. Studies of adhesion at 4 indicated that no binding occurred to normal or stimulated RPE, but binding to EC was observed, albeit reduced to 50% of the 37 binding level, and this implies that the LFA-3/CD2 adhesion pathway may also be involved in lymphocyte binding to EC. Overall, the results indicate a functional difference between RPE and EC affecting T-cell adhesion, migration and activation at the blood-retinal barrier, which must be considered when devising therapies to prevent lymphocyte infiltration of the eye.     

Synaptic pathways that shape the excitatory drive in an OFF retinal ganglion cell

Different types of retinal ganglion cells represent distinct spatiotemporal filters that respond selectively to specific features in the visual input. Much about the circuitry and synaptic mechanisms that underlie such specificity remains to be determined. This study examines how N-methyl-d-aspartate (NMDA) receptor signaling combines with other excitatory and inhibitory mechanisms to shape the output of small-field OFF brisk-sustained ganglion cells (OFF-BSGCs) in the rabbit retina. We used voltage clamp to separately resolve NMDA, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and inhibitory inputs elicited by stimulation of the receptive field center. Three converging circuits were identified. First is a direct glutamatergic input, arising from OFF cone bipolar cells (CBCs), which is mediated by synaptic NMDA and AMPA receptors. The NMDA input was saturated at 10% contrast, whereas the AMPA input increased monotonically up to 60% contrast. We propose that NMDA inputs selectively enhance sensitivity to low contrasts. The OFF bipolar cells, mediating this direct excitatory input, express dendritic kainate (KA) receptors, which are resistant to the nonselective AMPA/KA receptor antagonist, 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide disodium salt (NBQX), but are suppressed by a GluK1- and GluK3-selective antagonist, (S)-1-(2-amino-2-carboxyethyl)-3-(2-carboxy-thiophene-3-yl-methyl)-5-methylpyrimidine-2,4-dione (UBP-310). The second circuit entails glycinergic crossover inhibition, arising from ON-CBCs and mediated by AII amacrine cells, which modulate glutamate release from the OFF-CBC terminals. The third circuit also comprises glycinergic crossover inhibition, which is driven by the ON pathway; however, this inhibition impinges directly on the OFF-BSGCs and is mediated by an unknown glycinergic amacrine cell that expresses AMPA but not KA receptors.     

Smooth muscle cell phenotype alters cocultured endothelial cell response to biomaterial-pretreated leukocytes

Model in vitro culturing systems were developed to analyze roles of biomaterial-induced leukocyte activation on endothelial cell (EC) and smooth muscle cell (SMC) phenotype, and their crosstalk. Isolated monocytes or neutrophils were pretreated with model biomaterial beads and applied directly to "more secretory" (cultured in media containing 5% fetal bovine serum) or forced contractile (serum and growth factor starved) human aortic SMCs (HASMCs), or to the human aortic EC (HAEC) surface of HAEC/HASMC cocultures (HASMC phenotype varied to be "more or less secretory") for 5 or 24 h of static culture. Surface expression of proinflammatory [ICAM-1, VCAM-1, E-selectin], procoagulant (tissue factor), and anticoagulant (thrombomodulin) markers, as well as HAEC proliferation, were assessed by flow cytometry. Incubation of HAEC with biomaterial-pretreated monocytes (and neutrophils to lesser degree) suppressed HAEC proliferation and induced a proinflammatory/procoagulant HAEC phenotype. This HAEC phenotype was amplified in coculture with "more secretory" HASMCs and subdued in coculture with "less secretory" HASMCs. Direct incubation of biomaterial-pretreated monocytes or neutrophils with "more secretory" HASMCs further increased HASMC ICAM-1 and tissue factor expression. Direct incubation of biomaterial-pretreated monocytes or neutrophils with forced contractile HASMCs upregulated ICAM-1, VCAM-1, and tissue factor expression above the presence of serum-containing media alone.     

重组色素上皮衍生因子对人视网膜微血管内皮细胞迁移及凋亡的影响

目的: 构建rAAV2-PEDF腺相关病毒,研究色素上皮衍生因子(PEDF)基因高表达对人视网膜微血管内皮细胞的作用。方法: 将PEDF基因克隆、重组到腺相关病毒载体pSNAV,得到的pSNAV-PEDF后转染BHK细胞,用含G418的培养基进行筛选,得到稳定转染pSNAV-PEDF的生产细胞系,用重组1型单纯疱疹病毒HSV1-rc/△UL2感染细胞进行病毒包装,纯化后得到高滴度rAAV2-PEDF 病毒颗粒。按照10⁵v.g./cell的剂量进行rAAV2-PEDF病毒转染,分别设空白和阴性对照,激光共聚焦显微镜下观察GFP阳性细胞,Western blotting检测PEDF蛋白表达。Boyden小室法观察细胞迁移情况,流式细胞术检测细胞凋亡情况。结果: 通过PCR、酶切及基因测序的方法,证实rAAV2-PEDF构建成功。转染病毒48 h后,激光共聚焦显微镜下观察可见GFP阳性细胞,Western blotting检测,实验组PEDF表达明显强于其它组。rAAV2-PEDF干预正常氧条件下人视网膜微血管内皮细胞,正常对照组凋亡细胞比例为2.10%±0.53%,rAAV2-GFP组为3.40%±0.62%,rAAV2-PEDF组为1.60%±0.47%,各组间无显著差异(P＞0.05)。rAAV2-PEDF干预低氧条件下人视网膜微血管内皮细胞,单纯CoCl₂组凋亡细胞比例为4.00%±0.55%,CoCl₂+rAAV2-GFP组为6.10%±0.71%,CoCl₂+rAAV2-PEDF组为40.00%±2.10%。rAAV2-PEDF组与其它2组相比,有显著差异(P<0.05)。细胞迁移计数显示,正常对照组为33.0±2.7,rAAV2-GFP组为35.0±3.6,rAAV2-PEDF组为12.0±2.1,rAAV2-PEDF组与其它2组相比,有显著差异(P<0.05)。结论: 成功构建了rAAV2-PEDF,转染人视网膜血管内皮细胞后PEDF可稳定表达。PEDF高表达可显著抑制人视网膜微血管内皮细胞迁移并可在低氧条件下诱导其凋亡。     

Modification by some antagonists of the shape changes of venous endothelial cells in response to inflammatory agentsin vitro

Endothelial cells lining guinea pig inferior venae cavae change shape when exposed to histamine, bradykinin, A23187 or platelet-activating factor (PAF)in vitro. Pre-treatment of the endothelium with isoprenaline or quin 2 significantly reduced the shape changes produced in response to histamine, bradykinin and A23187, but not those to PAF. Since both isoprenaline and quin 2 may reduce the concentration of cytoplasmic Ca⁺⁺, the former by raising cyclic AMP (cAMP) levels and the latter by acting as a Ca⁺⁺ buffer, the results provide further evidence for the involvement of Ca⁺⁺ in the responses of large vein endothelial cells to inflammatory agentsin vitro. The effects of pre-treating the endothelium with the histamine receptor-blockers mepyramine (H₁) or cimetidine (H₂), or the bradykinin receptor-blockers des-arg⁹[leu⁸] bradykinin (B₁) or des-arg[Hyp³, Thi^5,8, D-Phe⁷] bradykinin (B₂) suggest that the response to histamine is both H₁ and H₂ receptor-mediated, while the response to bradykinin is only B₂ receptor-mediated.     

Cardiac hypertrophy alters myocardial response to ischaemia and reperfusion in vivo

The impact of cardiac hypertrophy on myocardial biochemical and physiological responses to ischaemia-reperfusion (I-R) was investigated in vivo. Hypertrophy was produced by aortic constriction (PH) or swimming training (TH). Open-chest rat hearts in PH, TH and a sedentary control group (SC) were subjected: (1) to ischaemia, by surgical occlusion of the main descending branch of the left coronary artery for 30 min; (2) to I-R, by releasing the occluded blood vessel for 15 min; or (3) to a sham operation. Ischaemia per se had little effect on heart oxidative and antioxidant status, or lipid peroxidation. However, I-R significantly decreased glutathione (GSH) content, increased glutathione disulfide (GSSG) content, and reduced GSH/GSSG ratio in the SC hearts. These alterations were associated with decreased activities of GSH peroxidase and GSSG reductase, and an increase in lipid peroxidation. Myocardial ATP, total adenine nucleotide content and energy charge in SC were significantly decreased after ischaemia, whereas levels of purine nucleotide derivatives, particularly adenosine, were elevated. No significant alteration of GSH status or adenine nucleotide metabolism occurred after ischaemia or I-R in hypertrophied hearts. In bodi PH and TH, glutathione content was significantly higher than in SC, whereas activities of GSH peroxidase and GSSG reductase were lower. TH rats maintained a higher heart rate (HR), peak systolic pressure, and energy charge during I-R. These data indicate that hypertrophied but well-functioned hearts may be more resistant to I-R induced disturbances of myocardial oxidative and antioxidant functions.     

Human endothelial cell activation and mediator release in response to Listeria monocytogenes virulence factors

The interaction of Listeria monocytogenes with endothelial cells represents a crucial step in the pathogenesis of listeriosis. Incubation of human umbilical vein endothelial cells (HUVEC) with wild-type L. monocytogenes (EGD) provoked immediate strong NO synthesis, attributable to listerial presentation of listeriolysin O (LLO), as the NO release was missed upon employment of a deletion mutant for LLO (EGD hly mutant) and was reproduced by purified LLO. Studies of conditions lacking extracellular Ca(2+) suggested LLO-elicited Ca(2+) flux as the underlying mechanism. In addition, HUVEC incubation with EGD turned out to be a potent stimulus for sustained (>12-h) upregulation of proinflammatory cytokine generation (interleukin 6 [IL-6], IL-8, and granulocyte-macrophage colony-stimulating factor). Use of deletion mutants for LLO (EGD hly mutant), listerial phosphatidylinositol-specific phospholipase C (EGD plcA mutant), broad-spectrum phospholipase C (EGD plcB mutant) and internalin B (EGD inlB mutant), as well as purified LLO, identified LLO as largely responsible for the cytokine response. Endothelial cells responded with diacylglycerole and ceramide generation as well as nuclear translocation of NF-kappa B to the stimulation with the LLO-producing strains EGD and Listeria innocua. The endothelial PC-phospholipase C inhibitor tricyclodecan-9-yl-xanthogenate as well as two independent inhibitors of NF-kappa B activation, pyrolidine dithiocarbamate and caffeic acid phenethyl ester, suppressed both the NF-kappa B translocation and the upregulation of cytokine synthesis. We conclude that L. monocytogenes is a potent stimulus of NO release and sustained upregulation of proinflammatory cytokine synthesis in human endothelial cells, both events being largely attributable to LLO presentation. LLO-induced transmembrane Ca(2+) flux as well as a sequence of endothelial phospholipase activation and the appearance of diacylglycerole, ceramide, and NF-kappa B are suggested as underlying host signaling events. These endothelial responses to L. monocytogenes may well contribute to the pathogenic sequelae in severe listerial infection and sepsis.     

Differential expression of selectins by mouse brain capillary endothelial cells in vitro in response to distinct inflammatory stimuli

Increased lymphocyte trafficking across blood-brain barrier (BBB) is a prominent and early event in inflammatory and immune-mediated CNS diseases. The adhesion molecules that control the entry of leukocytes into the brain have not been fully elucidated. Although the role of ICAM-1 and VCAM-1 has been well documented, the expression and role of selectins is still a matter of controversy. In a mouse syngenic in vitro BBB model, highly relevant for examining immunological events, mouse brain capillary endothelial cells (MBCECs) do not express selectins. Treatment of MBCECs with LPS, induced E- and P-selectin expression, whereas TNF-alpha or IFN-gamma treatments did not. Finally, P-selectin but not E-selectin expression was induced in IL-1beta treated MBCECs. Thus, our study suggests that diverse inflammatory stimuli could differentially regulate selectin expression at the BBB.     

Growth characteristics of retinal capillary endothelial cells compared with pulmonary vein endothelial cells in culture. The effect of pericytes on differentiation of endothelial cells

Bovine retinal capillary endothelial cells (RCECs) and pulmonary vein endothelial cells (PVECs) were isolated and investigated in plate culture, three-dimensional culture and in co-culture with pericytes. In plate culture, RCECs required growth factor in the medium for growth whereas PVECs did not. Phenotypic modulation (a tendency to become similar morphologically to smooth muscle cells, and to accumulate into thread-like structures) was observed in PVECs but not in RCECs. In three-dimensional culture, RCECs contracted, aggregated and were unable to proliferate. Proliferation was elicited when the gel matrix was adsorbed by fibronectin or upon co-culture with pericytes. In contrast, PVECs not only proliferated but also formed tubular structures. In co-culture with pericytes, PVECs in close contact with, or in near apposition to pericytes formed tubular structures earlier than those without contact in the same dish. These results provide new findings about differences in the growth characteristics of endothelial cells between microvessels and large vessels. In addition, it is considered that pericytes may promote tube formation by endothelial cells in three-dimensional culture.     

Accessory cell function of the endothelial cell: its role in the cellular immune response

We have proposed a hypothesis in which vascular endothelial cells, rather than or in addition to bone-marrow-derived cells, play an integral part in the antigen presentation event of cell-mediated immune phenomena including delayed-type hypersensitivity (DTH). Previously we have shown that a DTH ear-swelling response can be adoptively transferred in rats, using as few as 2 x 10(7) in vitro conditioned immune spleen cells. The transfer is antigen-specific, requiring the same sensitizing antigen in both the in vitro conditioning step and in the ear-test challenge. Adoptive transfer is also genetically restricted by alleles of the RT-1 region of the rat, requiring histocompatibility between immune donor cells and the naive recipient. In additional experiments, F1 to parental bone-marrow chimaeras were constructed such that the bone-marrow-derived cells and the non-bone-marrow-derived cells were of different RT-1 allotypes. When these chimaeras were used as adoptive transfer recipients, the transfer of DTH was possible only if the immune donor cells and the recipient non-bone-marrow-derived cells shared a common RT-1 haplotype, regardless of a shared haplotype with the bone-marrow-derived cells. These results point to a critical role for non-bone-marrow-derived cells (endothelial cells) in the DTH inflammatory response.     

Studies on ocular blood flow and retinal capillary permeability to sodium in pigs

A surgical technique was developed in pigs that permits access to the retinal venous plexus surrounding the optic nerve. The effect of surgery on ocular blood flow and capillary permeability was evaluated. Blood flow, determined by the labelled microsphere technique, did not differ significantly between operated and control eyes. Increased intraocular pressure in the operated eye reduced blood flow through the choroid and the anterior uvea in proportion to the reduction in perfusion pressure, while in the retina a smaller reduction in blood flow occurred indicating that autoregulatory mechanisms are involved in the control of retinal blood flow. The capillary permeability to sodium was studied by the single injection technique, using albumin as a reference substance. The fractional initial extractions from the choroidal and the retinal vessels were 0.77 and -0.001 respectively. The absence of a sodium extraction from the retinal vessel indicates that this part of the blood-retinal barrier was intact and that the blood drained by the retinal plexus is not mixed with blood from other sources.     

Positive association of anticytoskeletal endothelial cell antibodies and cardiac allograft rejection

Using an indirect immunofluorescence method on human umbilical vein endothelial cells (HUVEC), we investigated the presence of antiendothelial cell antibodies (AECA) in 136 pre- and posttransplant serum samples sequentially collected from 31 patients during the first year after cardiac transplantation. A healthy control group was also included (n = 87). Colocalization studies demonstrated a positive staining pattern of different cytoskeletal components (cytoskeletal–antiendothelial cell antibodies, CSK–AECA) including antivimentin, antiactin, antitubulin, and anticytokeratin among heart transplanted patients. Frequency of CSK–AECA in the control group and at day 0 in the transplant group was 18.3 and 22.5%, respectively (p = NS). A progressive increase in the frequency of CSK–AECA was observed after cardiac transplantation: 13.3% at day 15; 22.2% at day 30; 53.8% at day 90, and 58% at day 360. Interestingly, rejection episodes within the first year after transplantation occurred in 83.3% of CSK–AECA-positive and in 30.7% of CSK–AECA-negative patients (p = 0.0045). The presence of antibodies was detected prior to the rejection event and was associated with a poor clinical outcome: rejection episodes occurred at a mean of 36.14 ± 17 days after transplantation in patients with preexisting AECA and 174.25 ± 51.9 days after de novo antibody appearance in patients with no antibodies at day 0 (p = 0.029). In conclusion, a progressive increase in the frequency of CSK–AECA was observed following cardiac transplantation; the presence of these antibodies is strongly associated and precedes the rejection episodes. Thus, CSK–AECA could be a good marker for acute graft rejection.     

A morphometric study of the retinal ganglion cell response to optic nerve severance in the frog Rana pipiens

Summary This study examines the cell body response to axotomy of retinal ganglion cells in the frogRana pipiens. Cell soma sizes were measured in carefully matched regions of Nissl-stained wholemounted retinae after either nerve crush, nerve cut with stump separation, nerve crush with intraocular nerve growth factor (NGF) or nerve cut with NGF applied to the proximal stump. The state of axonal regeneration was also assessed in each case by anterograde transport of HRP.Following nerve crush axons crossed the lesion by 7 days, reached the chiasma by 14 days and entered the tectum around 20–30 days. The normally evenly stained ganglion cells exhibited granular Nissl staining at 7 and 10 days but very little change in soma size. From 10 to 28 days the mean retinal ganglion cell area increased by 102% and maintained this size until at least 75 days. By 102 days soma size had nearly returned to normal. A population of displaced amacrine cells retained a normal appearance and soma size throughout regeneration.Following nerve cut and stump separation the retinal ganglion cells were slightly more reactive in appearance at 7 days after crush but otherwise the soma reaction developed in a similar manner. Axon tracing revealed no extension beyond the lesion site in these animals and therefore the state of axonal growth did not affect the early soma response.NGF applied at the time of the lesion had no detectable effect on the soma reaction.Although many retinal ganglion cells re-establish contact with visual centres after axotomy in the frog, a considerable proportion die. This contrasts with both the goldfish, where all cells regenerate successfully, and various mammals, where none do so and all retinal ganglion cells die. All retinal ganglion cells in the frog undergo reactive changes similar to those of goldfish and there is no sign of the cell shrinkage seen in mammals. Therefore the cell death in frog would appear to be different from that in mammalian retina but similar to that of mammalian peripheral nerve in which chromatolysis generally preceeds death.