Lung epithelial cell lines in coculture with human pulmonary microvascular endothelial cells: development of an alveolo-capillary barrier in vitro

We have established a coculture system of human distal lung epithelial cells and human microvascular endothelial cells in order to study the cellular interactions of epithelium and endothelium at the alveolocapillary barrier in both pathogenesis and recovery from acute lung injury. The aim was to determine conditions for the development of functional cellular junctions and the formation of a tight epithelial barrier similar to that observed in vivo. The in vitro coculture system consisted of monolayers of human lung epithelial cell lines (A549 or NCI H441) and primary human pulmonary microvascular endothelial cells (HPMEC) on opposite sides of a permeable filter membrane. A549 failed to show sufficient differentiation with respect to formation of a tight epithelial barrier with intact cell-cell junctions. Stimulated with dexamethasone, the cocultures of NCI H441 and HPMEC established contact-inhibited differentiated monolayers, with NCI H441 showing a continuous, circumferential immunostaining of the tight junctional protein, ZO-1 and the adherens junction protein, E-cadherin. The generation of a polarized epithelial cell monolayer with typical junctional structures was confirmed by transmission electron microscopy. Dexamethasone treatment resulted in average transbilayer electrical resistance (TER) values of 500 Omega cm(2) after 10-12 days of cocultivation and correlated with a reduced flux of the hydrophilic permeability marker, sodium-fluorescein. In addition, basolateral distribution of the proinflammatory cytokine tumour necrosis factor-alpha caused a significant reduction of TER-values after 24 h exposure. This decrease in TER could be re-established to control level by removal of the cytokine within 24 h. Thus, the coculture system of the NCI H441 with HPMEC should be a suitable in vitro model system to examine epithelial and endothelial interactions in the pathogenesis of acute lung injury, infectious lung diseases and toxic lung injury. In addition, it could be used to improve techniques of lung drug delivery that also requires a functional barrier.     

Viral susceptibility of an immortalized human microvascular endothelial cell line.

CDC/EU.HMEC-1 is the first immortalized human microvascular endothelial cell line that retains morphologic, phenotypic, and functional characteristics of a normal human microvascular endothelial cell. This study evaluates a variety of viruses and their effects on this human endothelial cell line. The data indicate that adenoviruses, some herpesviruses, reoviruses and most picornaviruses grow well in HMEC-1, with distinctive cytopathic effects. The paramyxoviruses, however, do not appear to propagate, nor does HIV. The findings indicate that microvascular endothelial cells may act as a reservoir of these viruses; it also suggests the possibility that microvascular endothelium could be involved in the processing and presentation of antigen to immune cells.     

Mast cell granules cause proliferation of human microvascular endothelial cells

To investigate the possible role of mast cells in blood vessel formation, rat mast cell granules were studied for their proliferative effect on human microvascular endothelial cells. It was found that granules had a marked proliferative effect and that most of this activity was restricted to a dialyzable fraction. The dialyzable mast cell granule constituent histamine was found to be mitogenic, an effect that was shown with the use of specific agonists and antagonists to be mediated through an H1 receptor. H1 antagonists reduced the proliferation caused by the untreated mast cell granules to the level of proliferation caused by dialyzed granules, suggesting that all the dialyzable mitogenic activity was due to histamine. Histamine was also shown to cause proliferation of cells that were growth arrested by serum deprivation, suggesting that it is an endothelial growth factor. The compound responsible for the undialyzable mitogenic activity could not be identified but was shown not to be mast cell heparin. This demonstration of mast cell granule-induced endothelial proliferation suggests that the mast cell may be of importance in the process of angiogenesis.     

Interferon-beta inhibits activated leukocyte migration through human brain microvascular endothelial cell monolayer.

Perivascular leukocyte infiltration into the central nervous system is characteristic of multiple sclerosis (MS) pathology. Interferon-beta (IFN-beta) has shown efficacy in the treatment of patients with MS, but the relevant mechanisms remain incompletely understood. In this study the effects of IFN-beta on leukocyte transendothelial migration were investigated using cells relevant to MS pathogenesis, namely human brain microvascular endothelial cells (HB-MVEC). Activated, but not resting leukocytes exhibited a high transendothelial migration capacity. HB-MVEC prestimulated with tumor necrosis factor (TNF) and IFN-gamma significantly promoted leukocyte transendothelial migration. IFN-beta inhibited the activated leukocyte transendothelial migration on TNF/IFN-gamma-activated HB-MVEC in a dose-dependent manner. A matrix metalloproteinase (MMP) inhibitor and monoclonal antibodies to lymphocyte function antigen-1 (LFA-1) or intercellular adhesion molecule-1 (ICAM-1), but not to very late antigen-4 or to vascular cell adhesion molecule-1 significantly inhibited the transendothelial migration of stimulated leukocytes, suggesting that this phenomenon involves the LFA-1/ICAM-1 interaction and MMP. However IFN-beta did not interfere with the binding of leukocytes to HB-MVEC unless IFN-beta was preincubated with leukocytes or added to HB-MVEC at the time of stimulation. Furthermore IFN-beta did not modulate the expression of adhesion molecules on either stimulated leukocytes or activated HB-MVEC, but partially reduced TNF and interleukin-1 production from stimulated leukocytes during coculture with HB-MVEC. Interestingly, in the presence of IFN-beta, a significant down-regulation of MMP-9 release from stimulated leukocytes was found, especially for the activated form of MMP-9. These results indicate that inhibition of leukocyte transendothelial migration is an important mechanism accounting for the beneficial effects of IFN-beta in the treatment MS patients.     

Identification of antigens on porcine pulmonary microvascular endothelial cells recognized by human xenoreactive natural antibodies.

Transplantation of organs between species is prevented in part by humoral immune responses triggered by xenoreactive natural antibodies. Although the immune barrier to xenotransplantation of the lung is thought to be qualitatively and quantitatively different than the immune barrier to xenotransplantation of the kidney or heart, the antibody-antigen reactions responsible for rejection of pulmonary xenografts have not been characterized. To begin to address this issue for porcine lungs transplanted into humans, we analyzed the porcine pulmonary endothelial antigens recognized by human xenoreactive natural antibodies. Human and baboon natural antibodies recognized glycoprotein and glycolipid antigens isolated from the membranes of porcine pulmonary microvascular endothelial cells. The antigens included the integrin chains alpha1, alpha2, alpha3, alpha5, alpha(v), beta1, beta 3, the von Willebrand Factor, and fibronectin. These glycoproteins seemed to be recognized by the same antibodies that bind to porcine kidney or cardiac xenografts. Natural antibodies also recognized at least four glycolipids containing from one to five sugar residues, although at a lower level per unit number of cells than glycoprotein antigens. The epitope recognized by natural antibodies was predominantly Gal alpha1-3Gal, a structure expressed by lower mammals but not by humans and baboons. The antigens recognized by human antibodies in the porcine lung may provide insight into the pathogenesis of the rejection reaction. Moreover, the similarity of porcine lung antigens to porcine kidney and heart antigens suggests that differences in the rejection reactions between these organs reflects the distinct responses of the organs to humoral immunity.     

转录因子Bach1对人微血管内皮细胞的作用研究

 目的:研究转录因子Bach1对人微血管内皮细胞功能的影响。方法: 利用小干扰RNA（small interfering RNA,siRNA）细胞转染技术下调内皮细胞Bach1表达;用Matrigel管腔形成实验检测内皮细胞体外血管新生的能力;用Transwell小室法检测细胞迁移;用CCK-8法测定细胞增殖;用实时荧光定量PCR、Western blotting和ELISA法检测细胞中血红素氧合酶1（heme oxygenase 1,HO-1）和血管内皮细胞生长因子（vascular endothelial growth factor, VEGF）mRNA 和蛋白的表达情况;用转染报告基因的方法检测VEGF基因的转录活性。结果: 下调内皮细胞Bach1表达明显促进人微血管内皮细胞迁移和管腔形成能力,对内皮细胞增殖能力无明显影响;抑制Bach1表达促进内皮细胞HO-1 mRNA 和蛋白的表达,增加VEGF 转录活性及mRNA和蛋白的表达。结论: 抑制转录因子Bach1表达可增加内皮细胞HO-1和VEGF的表达,促进人微血管内皮细胞迁移和管腔形成,提示Bach1是负性调控血管新生的因子。     

改良贴壁法结合内皮细胞培养基培养小鼠肺微血管内皮细胞*☆

背景：肺微血管内皮细胞是研究微循环的重要内皮细胞模型之一,众多培养方法中单纯贴壁法操作相对简便,但耗时长,杂质细胞多,是批量培养细胞的最大障碍。 目的：建立优化的小鼠肺微血管内皮细胞体外培养方案,观察细胞生长状态并鉴定细胞性质。 方法：无菌状态下快速剪碎5日龄C57BL/6J小鼠的肺叶外周组织,肺组织颗粒贴壁法获得肺微血管内皮细胞,并用内皮细胞培养基培养。倒置显微镜观察培养细胞生长和行为状态,Ⅷ因子相关抗原免疫组化和免疫荧光进行细胞鉴定。 结果与结论：肺组织块培养24 h内可见梭形细胞爬出,传代后细胞生长迅速,形态规则呈鹅卵石状,纯度高达98%以上,结合Ⅷ因子相关抗原检测证实其为内皮细胞。结果可见联合运用肺组织颗粒贴壁和内皮细胞培养基可高效获得原代小鼠肺微血管内皮细胞。关键词：肺微血管内皮细胞;细胞培养;优化;鉴定;小鼠;血管组织工程 缩略语注释：PMVECs: pulmonary microvascular endothelial cells,肺微血管内皮细胞 doi:10.3969/j.issn.1673-8225.2012.15.007     

Generation of IgE-binding and IgG-binding factors from human lymphoblastoid cell lines

Mechanisms for degranulation in human eosinophils were evaluated. Release of eosinophil cationic protein (ECP), a unique eosinophil granule constituent, was measured upon exposure of purified eosinophils to a large surface consisting of Sephadex beads coated with serum, which leads to complement activation. Extracellular release of approximately 15% of the cellular ECP occurred both with eosinophils from patients with eosinophilia and normal people. Almost all eosinophils isolated from patients with eosinophilia and normal people adhered to serum-treated Sephadex. The data suggest that interaction through C3 receptors is a prerequisite for ECP release from eosinophils when exposed to serum-treated Sephadex. Both cytochalasin B, cytochalasin D and hydrocortisone reduced the release of ECP. Neither the cytochalasins nor hydrocortisone inhibited the adherence of eosinophils to the Sephadex beads. Thus the inhibitory effect of these agents on ECP release is a direct effect on the degranulation process. ECF-A, histamine and colchicine did not affect the release mechanism. No direct relationship was found between degranulation and oxidative burst inasmuch as some soluble mediators induced a high respiratory burst without a concomitant ECP release. Our data suggest that mechanisms for degranulation are not fully identical in eosinophils and neutrophils.     

氧糖剥夺/复氧所致细胞焦亡在肺微血管内皮细胞损伤中的作用

目的:探讨氧糖剥夺/复氧(OGD/R)是否导致人肺微血管内皮细胞(HPMVECs)焦亡及其在细胞损伤中的作用.方法:采用HPMVECs复制OGD/R细胞模型,模拟体外循环中HPMVECs缺血/再灌注过程.将细胞分为对照(control)组(正常培养)、OGD/R组(OGD 8 h+恢复12 h)及VX-765(casp...     

自噬减轻模拟缺血/再灌注微环境中肺微血管内皮细胞损伤

目的:观察体外模拟缺血/再灌注(ischemia/reperfusion,I/R)微环境下人肺微血管内皮细胞(human pulmonary microvascular endothelial cells,HPMVECs)的自噬变化,研究自噬在维持I/R条件下HPMVECs细胞存活及内皮屏障完整性中的作用。方法:用雷帕霉素(rapamycin,RAP)预处理HPMVECs,在缺糖缺氧/恢复糖和氧供(oxygen-glucose deprivation/oxygen-glucose restoration,OGD)模拟的I/R微环境中孵育细胞。应用Western blot及透射电镜法检测细胞自噬变化,用流式细胞术检测细胞凋亡,通透性小室法检测HPMVECs通透性。结果:OGD条件下HPMVECs的自噬水平明显升高,RAP预处理进一步上调了OGD条件下的细胞自噬。OGD组细胞凋亡率明显增高,细胞通透性增加。RAP预处理不仅降低了OGD引起的细胞凋亡率,而且减轻了OGD条件下细胞通透性。结论:自噬在I/R诱发的肺微血管内皮细胞损伤中发挥保护性作用,提高自噬水平有助于减少I/R条件下细胞凋亡并维持内皮屏障完整性。     

Inflammatory agonists that increase microvascular permeability in vivo stimulate cultured pulmonary microvessel endothelial cell contraction

Bovine pulmonary microvessel endothelial cells grown on a flexible substrate contract upon the addition of angiotensin II, thrombin, bradykinin, and U44069, a stable analogue of thromboxane A₂. All these agents promote inflammation and increase paracellular permeability in vivo or in vitro. The contractile response is mediated by intracellular and extracellular free calcium: the response is inhibited by TMB-8, an intracellular Ca²⁺ chelator, and EGTA. Contraction is inhibited by trifluoroperazine, a Ca²⁺-calmodulin antagonist, and by ML-7, an inhibitor of myosin light-chain kinase. Preincubation with PMA, a protein kinase C activator, prevents contraction by angiotensin II. The inactive analogue 4--phorbol 12,13-didecanoate does not inhibit contraction. In contrast cAMP, carbacyclin (a stable PGI₂ analogue), and isoproterenol, agonists known to stabilize the microvascular barrier against inflammatory agents, relax pulmonary microvessel EC. This direct evidence of the contractile potential of microvessel endothelial cells lends support to the theory that endothelial contraction leads to increased junctional permeability.This work was supported in part by NIH Grants HL 16714, HL 33104, GM 24891, and GM 35141.     

Human herpesvirus-8 infection of primary pulmonary microvascular endothelial cells

Human herpesvirus-8 (HHV-8) is the causative agent of Kaposi's sarcoma and is associated with the angioproliferative disorders primary effusion lymphoma and multicentric Castleman's disease. Evidence of HHV-8 infection within the pulmonary vasculature of patients with idiopathic pulmonary arterial hypertension (IPAH) has been described. We hypothesize that HHV-8 infection of pulmonary microvascular endothelial cells results in an apoptotic-resistant phenotype characteristic of severe pulmonary arterial hypertension. Our objective was to investigate the ability of HHV-8 to infect human pulmonary microvascular endothelial cells in vitro and characterize the phenotypic effect of this infection. Human pulmonary microvascular endothelial cells were exposed to HHV-8 using two methods (direct virus and co-culture technique). The presence of lytic and latent infection was confirmed. Changes in endothelial cell gene and protein expression and effects on cellular apoptosis were measured. HHV-8 can both lytically and latently infect primary human pulmonary microvascular endothelial cells in vitro. HHV-8 infection results in significant changes in gene expression, including alterations of pathways important to cellular apoptosis. HHV-8 infection also alters expression of genes integral to the bone morphogenic protein pathway, including down-regulation of bone morphogenic protein-4. Other genes previously implicated in the development of PAH are affected by HHV-8 infection, and cells infected with HHV-8 are resistant to apoptosis.     

Generation and characterisation of bovine antigen-specific T cell lines.

15 antigen-specific T cell lines have been generated from eight individual cattle immunised with ovalbumin. Several sources of interleukin-2 (IL-2) were used, including a supernatant from a gibbon cell line (MLA-Sup), human recombinant IL-2 (hrIL-2) and bovine recombinant IL-2 (brIL-2). These IL-2 sources were used alternately with autologous peripheral blood mononuclear cells (PBM) together with ovalbumin to generate the lines. They grew least well in MLA-Sup and best in brIL-2. FACS analysis indicated that the lines generated with the recombinant IL-2s were extremely homogeneous in that the majority of cells were BoCD4+ (bovine CD4 equivalent) and therefore of TH phenotype. The lines were antigen specific and responded to antigen only in the presence of autologous PBM and not allogeneic (MHC class I nonidentical) PBM. However, allogeneic PBM did support their proliferation to ConA. No MLR response was observed by the cell lines to allogeneic PBM. The response to antigen was inhibited by anti bovine class II mAbs but not an anti bovine class I mAb. The subpopulation of PBM which acted as antigen presenting cells for these bovine TH cell lines had typical macrophage characteristics.     

Acanthamoeba interactions with human brain microvascular endothelial cells

Acanthamoeba are opportunistic protozoan parasites that can cause fatal granulomatous amoebic encephalitis, however, the pathogenic mechanisms associated with this disease remain unclear. One of the primary factors in Acanthamoeba encephalitis is the haematogenous spread, followed by invasion of the blood-brain barrier resulting in the transmigration of Acanthamoeba into the central nervous system. In this study, we have used human brain microvascular endothelial cells, which constitute the blood-brain barrier and studied their interactions with Acanthamoeba. Using in vitro cultures, we showed that Acanthamoeba isolates belonging to genotypes T3, T4 and T11, exhibited increased cytotoxicity on human brain microvascular endothelial cells as well as exhibited higher binding and were considered potential pathogens. In contrast, Acanthamoeba isolates belonging to genotypes T2 and T7 exhibited minimal cytotoxicity and significantly less binding to human brain microvascular endothelial cells (P< 0.01). Furthermore, exogenous alpha-mannose inhibited binding but increased cytotoxicity of human brain microvascular endothelial cells. This is the first demonstration of Acanthamoeba interactions with primary human brain microvascular endothelial cells.     

Platelets play an important role in TNF-induced microvascular endothelial cell pathology.

Tumor necrosis factor-alpha (TNF) is known to be an important mediator in the pathogenesis of several inflammatory diseases. Vascular endothelial cells represent a major target of TNF effects. Platelet sequestration has been found in brain microvessels during experimental cerebral malaria and lung in experimental pulmonary fibrosis, implying that it may participate in TNF-dependent microvascular pathology. In this study, we investigated the mechanisms of platelet-endothelial interaction, using co-cultures between platelets and TNF-activated mouse brain microvascular endothelial cells (MVECs). Adhesion and fusion of platelets to MVECs was evidenced by electron microscopy, dye transfer, and flow cytometry. It was induced by TNF and interferon-gamma and depended on LFA-1 expressed on the platelet surface and ICAM-1 expressed on MVECs. The adhesion and fusion also led to the transfer of platelet markers on the MVEC surface, rendering these more adherent for leukocytes, and to an enhanced MVEC sensitivity to TNF-induced injury. These results suggest that platelets can participate in TNF-induced microvascular pathology.     

Impact of simulated microgravity on microvascular endothelial cell apoptosis

Cardiovascular deconditioning is known to occur in astronauts exposed to microgravity. Endothelial dysfunction at microcirculatory sites might contribute to cardiovascular deconditioning induced by weightlessness. Recent studies have reported changes in the morphology and gene expression of endothelial cells exposed to conditions of simulated microgravity. The present study was aimed at examining the effects of microgravity on the apoptosis of microvascular endothelial cells and the mechanism underlying these effects. We simulated a microgravity environment and found that microgravity induced microvascular endothelial cell apoptosis and that this effect was correlated with the downregulation of the PI3K/Akt pathway, increased expression of NF-κB, and depolymerization of F-actin. These findings may provide important insights into the origin of the adverse physiological changes occurring due to exposure to microgravity conditions.     

高浓度尿素诱导人脑微血管内皮细胞系产生炎性因子

目的研究高浓度尿素诱导人脑微血管内皮细胞系(HBMECs)产生炎性因子及其机制。方法以相同渗透压的甘露醇为对照,高浓度尿素(25 mmol/L)干预HBMECs 3、6、12和24 h后,免疫荧光法观察细胞内肿瘤坏死因子α(TNF-α)和诱导型一氧化氮合酶(i NOS)的表达。蛋白免疫印迹法(Western blot)检测TNF-α、i NOS、环氧合酶-2(cycloxygenase-2,COX-2)、核因子κB(NF-κB)/P65和p-P65的表达水平。一氧化氮(NO)试剂盒检测细胞NO含量。结果高浓度尿素增强细胞内TNF-α和i NOS表达。细胞TNF-α、COX-2和p-P65蛋白水平在3和6 h明显高于对照组(P0.01);i NOS蛋白水平持续增高(P0.01)。NO含量在3 h明显增多(P0.05)。结论高浓度尿素诱导人脑微血管内皮细胞产生炎性因子。     

重组sICAM-1对PMA刺激的白细胞与\=肺微血管内皮细胞粘附的影响

目的:探讨重组sICAM-1对大鼠白细胞与肺微血管内皮细胞粘附的影响。方法:采用原代培养的大鼠肺微血管内皮细胞及⁹⁹Tm-HMPAO标记的白细胞,观察不同浓度的sICAM-1、CA7(sICAM-1的单抗)以及sICAM-1·CA7(sICAM-1的二聚体)对PMA刺激的大鼠白细胞与肺微血管内皮细胞粘附的影响。结果:sICAM-1与CA7即使在100mg/L也不能抑制白细胞与肺微血管内皮细胞的粘附,而其二聚体在20mg/L和40mg/L即可抑制42%和50%的细胞粘附(P＜0.05)。结论:sICAM-1对细胞粘附的抑制作用很弱,可能与其单体形式有关。