Expression of the endothelial markers PECAM-1, vWf,and CD34 in vivo and in vitro

EC culture models are essential to study pathological alterations of endothelial cells (ECs) in pulmonary vascular diseases under standardized conditions. Nevertheless, little is known about the spectrum of alterations of vessel-specific endothelial phenotypes in monolayer cultures. For the comparative study of endothelial markers in vivo and in vitro we investigated immunohistochemically the expression of PECAM-1, vWf, and CD34 by pulmonary ECs in vivo and in stimulated/unstimulated human umbilical vein endothelial cells (HU-VEC) and human pulmonary microvascular endothelial cells (HPMEC). In vivo, vessel type-specific expression patterns were found for vWf and CD34, while PECAM-1 was homogeneously and strongly expressed. While all HUVEC showed a marked vWf staining, about two-thirds of HPMEC exhibited a strong and the rest a moderate vWf staining. In both in vitro models all ECs were clearly PECAM-1-positive. However, only about 20% of the HUVEC and HPMEC were CD34-positive. Our results demonstrate the reduced expression of vessel type-specific endothelial phenotypes by endothelial monolayer cultures, stressing the need to improve culture conditions as well as develop cocultures and three-dimensional culture models. Moreover, the need for endothelial markers specific for single microvascular type ECs becomes obvious in order to establish cultures consisting of only one microvascular ECs subpopulation.     

Heterogeneous expression of cell adhesion molecules by endothelial cells in ARDS

ARDS (acute respiratory distress syndrome) can be associated with septic shock and multiple organ failure caused by an uncontrolled systemic inflammatory response to Gram-negative bacterial infection. While in animal models the key role of the endothelial adhesion molecules ICAM-1, E-selectin, and VCAM in ARDS has been extensively studied, there are scarcely any corresponding pathomorphological studies of human lung tissue. Hence, little is known about whether there is a comparable, or even heterogeneous, expression pattern of these molecules in the human pulmonary vasculature. This study was therefore undertaken to investigate the immunohistochemical expression of the constitutively expressed PECAM (CD31) and the inducible molecules ICAM-1, E-selectin, and VCAM in ARDS lungs from patients who had died in septic shock induced by Gram-negative bacteria. While in all specimens (ARDS and normal lungs) there was homogeneous strong expression of PECAM in all vessels, ICAM-1 was clearly up-regulated in ARDS lungs. E-selectin and VCAM were not expressed by endothelial cells (ECs) in normal lungs, but in ARDS lungs there was strong expression of both molecules in larger vessels, while in the capillaries there was only mosaic-like weak expression of a few ECs. This immunohistochemical investigation demonstrates the induction and up-regulation of adhesion molecules in human ARDS lungs, comparable to that described in animal models. There is also markedly heterogeneous expression of E-selectin and VCAM, indicating toporegional differences in the function of pulmonary ECs.     

Human papillomavirus-16-E7 oncoprotein enhances the expression of adhesion molecules in cervical endothelial cells but not in human umbilical vein endothelial cells.

OBJECTIVES: E7 is one of the oncoproteins encoded by human papillomavirus-16 (HPV-16), the major etiologic factor responsible for cervical cancer. Human papillomavirus-16-E7 expressed by human uterine cervix carcinoma cells is also released in the extracellular compartment where it induces immune suppression. We investigated whether E7 was also responsible for the enhanced endothelial adhesiveness required in cancer progression. STUDY DESIGN/METHODS: We treated cervical microvascular endothelial cells (CrMVEn) and human umbilical vein endothelial cells (HUVEC) with E7, tumor necrosis factor-alpha (TNF-alpha), and hydrogen peroxide (H2O2) and measured the expression of E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) by fluorescent-activated cell sorter analysis. RESULTS: E7 strongly induced the expression of E-selectin, ICAM-1, and VCAM-1 in CrMVEn, but not in HUVEC. Tumor necrosis factor-alpha further increased the endothelial expression of adhesion molecules in CrMVEn. Hydrogen peroxide pre-treatment resulted in an enhanced ICAM-1 and a decreased E-selectin and VCAM-1 expression. We also show indirect effects when endothelial cells were stimulated with the supernatant of E7-pretreated macrophages. CONCLUSIONS: These results show that HPV-16-E7 oncoprotein strongly induces adhesion molecules expression in organ-specific endothelial cells.     

Vascularization and gene regulation of human endothelial cells growing on porous polyethersulfone (PES) hollow fiber membranes

Open-cell hollow fibers made of polyethersulfone (PES) manufactured in the absence of solvents with pore diameters smaller than 100 microm were examined for vascularization by human endothelial cells. The goal of this study was to determine whether the 3-D porous character of the PES surface affected human endothelial cell morphology and functions. Freshly isolated human endothelial cells from the skin (HDMEC), from the lung (HPMEC) and from umbilical cords (HUVEC) and two human endothelial cell lines, HPMEC-ST1.6R and ISO-HAS.c1 were added to PES fibers and cell adherence and growth was followed by confocal laser scanning microscopy. Prior coating of PES with gelatin or fibronectin was necessary for adhesion and spreading of cells over the uneven porous surface with time. Confluent cells exhibited typical strong PECAM-1 expression at cell-cell borders. Little expression of the activation markers E-selectin, ICAM-1, and VCAM-1 was observed by RT-PCR of endothelial cells growing on PES. However, after stimulation for 4h by LPS, activation of these markers was observed and it was shown by immunofluorescent staining that induction occurred in most of the cells, thus confirming an intact functionality. Finally, cells growing as a monolayer on PES migrated to form microvessel-like structures when placed under conditions that stimulated angiogenesis. Thus, human endothelial cells grown on fibronectin-coated PES fibers retain important endothelial-cell specific morphological and functional properties and PES may serve as a useful biomaterial in tissue engineering and biotechnology applications.     

Human intestinal endothelium shows high susceptibility to cytomegalovirus and altered expression of adhesion molecules after infection

Human cytomegalovirus (HCMV) causes gastro intestinal disease with ulcerations, apparently as a consequence of cytopathic damage to endothelial cells (EC) and subsequent microvascular obliteration. In this study we showed that cultured human intestinal microvascular endothelial cells (HIMEC) are much more susceptible to HCMV infection than human umbilical vein endothelial cells (HUVEC). When both cell types were challenged with a clinical isolate of HCMV (10 pfu per cell), 30% of HIMEC expressed HCMV immediate early proteins, but only 10% of HUVEC. Enhanced susceptibility was also reflected in the expression of early and late HCMV proteins. In addition, the interleukin-1beta (IL-1beta)-induced cellular expression of adhesion molecules differed between HIMEC and HUVEC after HCMV-infection. E-selectin was unaffected in HUVEC but increased in HIMEC, whereas vascular cell adhesion molecule (VCAM)-1 was increased in HUVEC but decreased in HIMEC. Furthermore, HCMV-infection enhanced the expression of intercellular adhesion molecule (ICAM)-1 in both cell types. In conclusion, the enhanced susceptibility to HCMV infection observed in HIMEC and the elevated expression of E-selectin and ICAM-1 observed in these cells may provide an indication to the liability of developing gastrointestinal HCMV disease and may have a possible relevance to the survival of intestinal transplants.     

Inhibition of endothelial cell adhesion molecule expression with SJC13, an azaindolidine derivative,in vitro

Stimulation of cultured human umbilical vein endothelial cells (HUVEC) with lipopolysaccharide (LPS) induces adherences for human promyelocytic cell line HL60. Adherence of HL60 cells to HUVEC stimulated with LPS for 4h was completely inhibited by pretreatment with SJC13, an azaindolidine derivative. The mechanism whereby SJC13 inhibits the adhesiveness of HUVEC was investigated. Pretreatment of SJC13 inhibited LPS-induced expression of E-selectin and vascular cell adhesion molecule-1 (VCAM-1), but not intercellular adhesion molecule-1 (ICAM-1), in HUVEC, determined by flow cytometry and cellular enzyme-linked immunosorbent assay (cell-ELISA). The inhibitory activity was concentration dependent between 62.5 and 1,000 g/ml. SJC13 also selectively inhibited LPS-induced increases in E-selectin and VACM-1 mRNAs, indicating that the action of SJC13 is to inhibit synthesis of these molecules. These data demonstrate that SJC13 is capable of selectively inhibiting the expression of E-selectin and VCAM-1, but not ICAM-1, in endothelial cells.accepted by I. Ahnfelt-Rønne     

Cyclic-strain-induced endothelial cell expression of adhesion molecules and their roles in monocyte-endothelial interaction.

Vascular endothelial cells (ECs) are constantly subjected to hemodynamic forces that may regulate monocyte-endothelial interaction in vivo. To examine the effects of cyclic strain on endothelial expression of monocyte adhesion molecules, E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) ECs were exposed to physiologically relevant levels of cyclic strain. When ECs were under 25% maximal strain at 30 cycles/min for 24 h, the expression of E-selectin significantly (p<0.05) increased, by 83%, compared to control ECs under static conditions. Similarly, monocyte adhesion to ECs under strain (maximum of 15 or 25% at 30 and 60 cycles/min for 24 h) also significantly (p<0.05) increased, by >82%. This cyclic-strain-induced monocyte adhesion was substantially inhibited (83.5%) by anti-E-selectin antibody. ICAM-1 expression also significantly increased, by 62%, when ECs were under 25% maximal strain at 30 cycles/min for 3 h whereas VCAM-1 expression by ECs under strain (for 0.5, 3, and 24 h) did not change compared to static ECs. When ECs were treated with anti-ICAM-1 antibody and monocytes with anti-VLA-4 antibody, an increase in monocyte adhesion to ECs under cyclic strain was reduced significantly. These results demonstrate that cyclic strain can induce EC expression of monocyte adhesion molecules E-selectin, ICAM-1, and VCAM-1 in a time-dependent manner and thus can mediate monocyte adhesion.     

Lymphocyte-facilitated tumour cell adhesion to endothelial cells: the role of high affinity leucocyte integrins

AIM: Lymphocytes transiently express an active form of the beta_2 integrin LFA-1 (LFA-1Af) which has conformational changes in extracellular domains enabling higher affinity binding to the ligand ICAM-1. In this study, we investigated the role of lymphocytes bearing LFA-1Af as potential mediators of binding of ICAM-1-positive tumour cells to endothelium. METHODS: LFA-1 expression on 51Cr-PBLs was modulated in order to express high affinity LFA-1Af and conjugates were formed with 35S-labelled COLO526. The binding of the conjugates to resting or IL-1beta-stimulated human umbilical vein endothelial cells (HUVECs) was then assessed via a modified radioactive HUVEC binding assay. In addition, the binding of PBL-COLO526 conjugates to HUVECs was demonstrated by confocal microscopy. RESULTS: The binding of COLO526 to endothelial cells did not change significantly between unstimulated and stimulated HUVECs. In addition, pre-incubating the COLO526 with fresh PBLs did not significantly alter the binding of COLO526 to resting or activated HUVECs; whereas, in the presence of PBLs with LFA-1Af, the COLO526 conjugate binding dramatically increased from basal levels to 41% on resting HUVECs and 81% on stimulated HUVECs. COLO526-PBL(LFA-1Af) conjugate adhesion to stimulated HUVECs was inhibited by blocking antibody to LFA-1 (50%), VLA-4 (32%) or L-selectin (40%). Antibodies to the HUVEC adhesion molecules ICAM-1, VCAM-1 and E-selectin also inhibited COLO526-PBL(LFA-1Af) conjugate binding to activated HUVECs by 79, 60 and 73%, respectively. CONCLUSIONS: PBLs bearing LFA-1Af can enhance COLO526 adhesion to both resting and activated HUVECs. Furthermore, blocking studies demonstrate that a range of pathways are involved in this phenomenon (LFA-1/ICAM-1, VLA4/VCAM-1, L-selectin/E-selectin). These studies have identified a novel alternative pathway for lymphocyte-facilitated tumour cell adhesion to endothelial cells.     

Differential adhesion of polymorphous neutrophilic granulocytes to macro- and microvascular endothelial cells under flow conditions.

OBJECTIVE: As one of the important active barriers in the human organism, endothelial cells (EC) play a central role in the biological reaction to a variety of stimuli, e.g. during the induction and regulation of inflammation, as well as in the reaction to transplantation and biomaterial implantation. In the study of endothelial function, the most widely used in vitro model is that of human umbilical vein EC (HUVEC), i.e. an EC type of embryonic and macrovascular origin. However, many of the important pathological processes occur at microvascular level, thus questioning the validity of the HUVEC model. Moreover, the morphological and functional heterogeneity of the endothelium in the various organs, e.g. kidney, liver and lung, must be taken into consideration. The purpose of the present study was to use a dynamic cell culture system to compare the reactions of HUVEC and human pulmonary microvascular EC (HPMEC) to pro-inflammatory stimulation. METHODS: HUVEC and HPMEC in monolayer culture were stimulated by tumor necrosis factor-alpha (TNFalpha) in a parallel-plate flow chamber. Short- (4 h) and long-term (12 h) stimulation were compared. As a functional parameter, the adhesion of human peripheral blood polymorphonuclear granulocytes (PMN) to EC was quantitated both under venous and arterial flow conditions. RESULTS: Short-term (4 h) TNFalpha stimulation and venous flow conditions elicited a 32% higher PMN adhesion to HPMEC compared with HUVEC, whereas under arterial flow conditions no statistically significant differences were found. Following longer-term (12 h) TNFalpha stimulation, PMN adhesion to HPMEC was 65% higher than to HUVEC under venous flow. Under arterial flow no differences were detected. CONCLUSION: The present results provide new data on the heterogeneity of the endothelium and affect a central element in microvascular pathology, namely granulocyte-endothelial interactions. Moreover, this paper emphasizes the necessity to evaluate the in vitro models of the endothelium with respect to the extrapolation to the situation in vivo.     

切应力和溶血磷脂酰胆碱对内皮细胞表面黏附分子表达的影响

在体内 ,内皮细胞的功能不仅受化学因子的调节 ,而且还受力学因素的影响。为探讨流体切应力和溶血磷脂酰胆碱 ( L ysophosphatidylcholine,L yso- PC)的双重作用对培养的人脐静脉内皮细胞 ( Hum an um bilical veinendothelial cells,HU VECs)表面黏附分子 ICAM- 1、VCAM- 1、E- selectin表达的影响 ,采用流式细胞仪技术检测了L yso- PC( 3 0 μg/m l)和流体切应力 ( 2 .2 3、4.2 0 dyne/cm2 )的协同作用下内皮细胞黏附分子表达的变化。结果显示 :在受剪切作用之前 ,用 L yso- PC孵育激活内皮细胞 ,或预先剪切后再用 L yso- PC孵育 ,内皮细胞的 ICAM- 1和VCAM- 1表达与两种刺激同时作用相比 ,显著增加 ( P<0 .0 5 ) ;切应力或 L yso- PC的单独作用 ,以及两种刺激同时存在对 HU VEC的 E- selectin表达无显著影响。而在受剪切作用之前 ,用 L yso- PC孵育激活内皮细胞 ,或预先剪切后再用 L yso- PC孵育 ,内皮细胞的 E- selectin表达与两种刺激同时作用相比 ,显著增加 ( P<0 .0 5 )。结论认为 :即使在不利于细胞黏附的力学环境中 ,流体切应力与 L yso- PC的协同作用 ,也可能是在炎症部位单核细胞对内皮细胞募集增加的重要原因之一     

Borrelia burgdorferi upregulates expression of adhesion molecules on endothelial cells and promotes transendothelial migration of neutrophils in vitro.

The accumulation of leukocytic infiltrates in perivascular tissues is a key step in the pathogenesis of Lyme disease, a chronic inflammatory disorder caused by Borrelia burgdorferi. During an inflammatory response, endothelial cell adhesion molecules mediate the attachment of circulating leukocytes to the blood vessel wall and their subsequent extravasation into perivascular tissues. Using cultured human umbilical vein endothelial cells (HUVEC) in a whole-cell enzyme-linked immunosorbent assay, we demonstrated that B. burgdorferi activated endothelium in a dose- and time-dependent fashion as measured by upregulation of the adhesion molecules E-selectin, vascular cell adhesion molecule 1 (VCAM-1), and intercellular adhesion molecule 1 (ICAM-1). As few as one spirochete per endothelial cell stimulated increased expression of these molecules. Expression of E-selectin peaked after spirochetes and HUVEC were coincubated for 4 h and returned to near-basal levels by 24 h. In contrast, expression of VCAM-1 and ICAM-1 peaked at 12 h and remained elevated at 24 h. HUVEC monolayers cultured on acellular amniotic tissue were used to investigate the consequences of endothelial cell activation by spirochetes. After incubation of HUVEC-amnion cultures with B. burgdorferi, subsequently added neutrophils migrated across the endothelial monolayers. This process was mediated by E-selectin and by CD11/CD18 leukocytic integrins. The extent of migration depended on both the number of spirochetes used to stimulate the HUVEC and the length of the coincubation period. These results raise the possibility that B. burgdorferi induces a host inflammatory response and accompanying perivascular damage through activation of vascular endothelium.     

Role of Tyrosine Kinase Enzymes in TNF-α and IL-1 Induced Expression of ICAM-1 and VCAM-1 on Human Umbilical Vein Endothelial Cells

The aim of this study was to analyse the potential roles of protein kinase enzymes in tumour necrosis factor-α (TNF-α) and interleukin-1 (IL-1) induced expression of the adhesion molecules intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on human umbilical vein endothelial cells (HUVEC). The authors observed a marked increase in ICAM-1 and VCAM-1 expression on HUVEC stimulated for 24 h by TNF-α (10 ng/ml) or IL-1 (20 ng/ml). Pre-treatment of HUVEC for 30 min with protein tyrosine kinase (PTK) inhibitors genistein and herbimycin A (10 μg/ml and 0.5 μg/ml, respectively) before stimulation with IL-1 did not affect the expression of these molecules. Similar results were observed with respect to VCAM-1 expression on HUVEC stimulated by TNF-α. In contrast, pre-incubation of HUVEC with PTK inhibitors prior to the addition of TNF-α significantly enhanced subsequent expression of ICAM-1, although spontaneous expression of ICAM-1 on unstimulated HUVEC was unaffected. Western blot analysis demonstrated a significant increase in phosphorylated tyrosine protein levels in HUVEC stimulated by TNF-α , and significantly lower levels of these proteins in TNF-α stimulated HUVEC pre-treated with PTK inhibitors. These results demonstrate that IL-1 induced ICAM-1 and VCAM-1 expression does not result from activation of PTK-dependent pathways. In the case of TNF-α induced responses, the selective co-stimulatory effect of this cytokine in combination with PTK inhibitors on ICAM-1 expression suggests a complicated intracellular pathway of TNF-α induced ICAM-1 expression, possibly involving down-modulation of increases in ICAM-1 by PTK enzymes.     

Complementary targeting of liposomes to IL-1α and TNF-α activated endothelial cells via the transient expression of VCAM1 and E-selectin

Inflammation is in part defined by the transient upregulation of cell adhesion molecules on the surface of endothelial cells (ECs) in response to cytokines. We hypothesized that liposomes with a complementary surface presentation of antibodies to the pattern of molecules on the EC surface may enhance targeting. We quantified the expression of vascular cell adhesion molecule-1 (VCAM1) and endothelial leukocyte cell adhesion molecule-1 (E-selectin) on ECs upon exposure to either tumor necrosis factor-α (TNF-α) or interleukin-1α (IL-1α) as a function of time. Liposomes, composed of 95 mol% dioleoyl phosphatidylcholine (DOPC) and 5 mol% dodecanyl phosphatidylethanolamine (N-dod-PE), were prepared by conjugating different molar ratios of antibodies against VCAM1 (aVCAM1) and E-selectin (aE-selectin). Increased binding was observed when immunoliposomes complemented the presentation of VCAM1:E-selectin expressed on TNF-α activated ECs. The 1:1 aVCAM1:aE-selectin liposomes had maximal binding at both 6 and 24 h on IL-1α activated ECs due to differences in molecular organization. The results demonstrate that liposomes targeting to inflamed endothelium may be optimized by exploiting the dynamic expression of VCAM1 and E-selectin on the EC surface.     

E-selectin and intercellular adhesion molecule-1 are released by activated human endothelial cells in vitro.

Endothelial cells respond to several cytokines by a rapid increase in expression of the adhesion molecules E-selectin and intercellular adhesion molecule-1 (ICAM-1), followed by a gradual decline. The fate of these molecules, which was so far unknown, was studied. Specific sandwich ELISA for the detection of soluble (s)E-selectin and sICAM-1 were developed. In supernatant, centrifuged 3 hr at 100,000 g to remove microparticles, from human umbilical vein endothelial cells (HUVEC) activated with tumour necrosis factor (TNF), interleukin-1 (IL-1) or lipopolysaccharide (LPS), E-selectin and ICAM-1 molecules could be detected. Biochemical analysis revealed that sE-selectin migrated as a band of approximately 94,000 MW. The amount of soluble adhesion molecules released was directly correlated with cell surface expression. Maximal release of E-selectin was observed 6-12 hr after activation of HUVEC and decreased to below detection limit 24 hr after activation. After activation, release of ICAM-1 gradually increased with ICAM-1 cell surface expression, and reached a plateau after 24 hr, which was constant for 3 days. Since E-selectin and ICAM-1 are highly expressed at inflammatory sites, the resulting high concentrations of released E-selectin and ICAM-1 may affect interactions of leucocytes with endothelial cells. The physiological role, however, of the release of E-selectin and ICAM-1 remains to be elucidated.     

Differential influences of bFGF and VEGF on the expression of vascular cell adhesion molecule-1 on human umbilical vein endothelial cells]

A fundamental feature of inflammation includes angiogenesis, adhesion of leukocytes to vascular endothelium, and entry of leukocytes into inflamed tissues. Recent studies have suggested that angiogenesis and cellular adhesion may be mutually linked processes. Both basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) have been shown to facilitate angiogenesis. However, their roles in the expression of adhesion molecules on the endothelial cells have not been clarified. The current studies therefore examined the effect of bFGF and VEGF on the expression of vascular cell adhesion molecule-1 (VCAM-1) on human umbilical vein endothelial cells (HUVEC) stimulated with tumor necrosis factor alpha (TNF-alpha). HUVEC (1 x 10(4)/well) were incubated in a 96 well microtiter plate with culture medium containing endothelial cell growth supplement (ECGS) for 24 h. After the incubation, culture medium was replaced by ECGS free culture medium with or without TNF-alpha (10 ng/ml), bFGF (10 ng/ml) and VEGF (10 ng/ml), and the culture was further carried out for additional 24 h. The expression of VCAM-1, E-selectin, and intercellular adhesion molecule-1 (ICAM-1) was measured by cell ELISA and the proliferation of HUVEC was measured by MTT colorimetric assay. Soluble VCAM-1 (sVCAM-1) in the supernatants were assessed by ELISA. Although, both bFGF and VEGF supported the proliferation of HUVEC, bFGF, but not VEGF, selectively suppressed the expression of VCAM-1 on HUVEC stimulated with TNF-alpha. The expression of ICAM-1 and E-selectin induced by TNF-alpha was not inhibited by either bFGF or VEGF. In addition, bFGF also decreased the levels of sVCAM-1 in the supernatants of TNF-alpha stimulated HUVEC. The data indicate that bFGF, but not VEGF, suppresses the production of VCAM-1 by HUVEC under stimulation with TNF-alpha. These results therefore suggest that angiogenic cytokines bFGF and VEGF play different roles in the regulation of the expression of adhesion molecules on endothelial cells under inflammation.     

Evidence for endocytosis of E-selectin in human endothelial cells.

E-selectin is an inducible adhesion molecule on endothelial cells. The internalization of this glycoprotein was investigated on tumor necrosis factor (TNF)-activated cultured human umbilical vein endothelial cells (HUVEC). Kinetics of intercellular adhesion molecule-1 (ICAM-1) were studied in parallel experiments. Internalization studies were performed with radioiodinated antibodies in an acid elution endocytosis assay, and by immunohistology; both approaches gave equivalent results. [125I]ENA1, a monoclonal antibody (mAb) specific for E-selectin, was internalized at a rate of approximately 1.7% of the membrane-bound [125I]mAb per minute. In contrast, less than 0.1% of membrane-bound [125I]RR1/1, an mAb specific for ICAM-1, was internalized per minute. TNF-activated HUVEC were immunostained and examined by light microscopy (LM) and electron microscopy (EM). LM revealed the presence of ENA1, but not RR1/1, after 30 minutes of incubation with these mAb in cytoplasmic vesicles, which were characterized as multivesicular bodies by EM. Without previous mAb exposure of the endothelial cells, both high amounts of E-selectin and bovine serum albumin complexed to colloidal gold, used as a marker for fluid-phase internalization, were detected in the same organelles, thus arguing against mAb interaction-induced E-selectin internalization. Furthermore, the amount of E-selectin surface expression was not influenced by ongoing mAb presence, also arguing against mAb interference with normal E-selectin kinetics. Taken together, these results indicate that TNF-activated HUVEC constitutively internalize E-selectin. Physiological significance of E-selectin internalization in the regulation of E-selectin membrane expression, and in clearing E-selectin ligands from the circulation, needs further investigation.     

Leucocyte Endothelial Cell Adhesion: a Study comparing Human Umbilical Vein Endothelial Cells and the Endothelial Cell Line EA-hy-926

EA-hy-926 is a cell line produced by hybridizing human umbilical vein endothelial cells (HUVEC) and the epithelial cell line A549. To establish whether EA-hy-926 could be used as a model for endothelial cells (EC) in leucocyte-EC adhesion interactions, the effect of interleukin-4 (IL-4), tumour necrosis factor (TNF) or interferon-γ (IFN) stimulation on their adhesiveness and expression of E-selectin, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) was compared with that of HUVEC and A549. Although HUVEC exhibited increased adhesiveness and adhesion molecule expression with IL-4, TNF or IFN, EA-hy-926 exhibited these responses only with TNF. CD11/CD 18-dependent binding accounted for a significant component of basal binding to HUVEC and EA-hy-926, but did not account for the increased binding of T cells, JY, J6, ICH-BJ or ICH-KM cell lines to TNF-stimulated monolayers. At least part of the CD1l/CD18-independent adhesion was attributable to VCAM-1 induction on HUVFC and FA-hy-926. TNF-stimulation also induced F-selectin expression on EA-hy-926 and HUVEC and an accompanying increase in neutrophil (PMN) binding. The EA-hy-926 cells used in this study, therefore, showed responses similar to HUVEC when stimulated with TNF but not when stimulated with IL-4 or IFN.     

Bartonella henselae Induces NF-κB-Dependent Upregulation of Adhesion Molecules in Cultured Human Endothelial Cells: Possible Role of Outer Membrane Proteins as Pathogenic Factors

The endothelium is a specific target for Bartonella henselae, and endothelial cell infection represents an important step in the pathogenesis of cat scratch disease and bacillary angiomatosis. Mechanisms of Bartonella-endothelial cell interaction as well as signaling pathways involved in target cell activation were analyzed. B. henselae strain Berlin-1, isolated from bacillary angiomatosis lesions of a human immunodeficiency virus-infected patient, potently stimulated human umbilical cord vein endothelial cells (HUVEC), as determined by NF-kappaB activation and enhanced adhesion molecule expression. These effects were accompanied by increased PMN rolling on and adhesion to infected endothelial cell monolayers, as measured in a parallel-plate flow chamber assay. Monoclonal antibodies against E-selectin significantly reduced PMN rolling and adhesion. In our hands, B. henselae Berlin-1 was substantially more active than the typing strain B. henselae ATCC 49882. E-selectin and ICAM-1 upregulation occurred for up to 9 days, as verified by Northern blotting and cell surface enzyme-linked immunosorbent assay. Induction of adhesion molecules was mediated via NF-kappaB activation and could be blocked by a specific NF-kappaB inhibitor. Additional studies indicated that B. henselae-induced effects did not require living bacteria or Bartonella lipopolysaccharides. Exposure of HUVEC to purified B. henselae outer membrane proteins (OMPs), however, reproduced all aspects of endothelial cell activation. In conclusion, B. henselae, the causative agent of cat scratch disease and bacillary angiomatosis, infects and activates endothelial cells. B. henselae OMPs are sufficient to induce NF-kappaB activation and adhesion molecule expression followed by enhanced rolling and adhesion of leukocytes. These observations identify important new properties of B. henselae, demonstrating its capacity to initiate a cascade of events culminating in a proinflammatory phenotype of infected endothelial cells.     

脓毒症大鼠肺血管内皮细胞、细胞间粘附分子1和E-选择素的变化及其意义

目的:观察脓毒症大鼠肺血管内皮细胞(VEC)、细胞间黏附分子1和E-选择素的变化特点并探讨其意义.方法:60只SD大鼠随机分成对照组和脓毒症组.以脂多糖(LPS)静脉注射制备大鼠脓毒症模型,采用逆转录聚合酶链反应(RT-PCR)和免疫组织化学方法研究ICAM-1和E-选择素的表达;用Hoechest染色评价肺VEC凋亡;用电子显微镜观察肺VEC.结果:脓毒症组大鼠肺ICAM-1 mRNA和ICAM-1蛋白的表达与对照组比较明显增加(P<0.01),脓毒症组ICAM-1 mRNA和ICAM-1蛋白的表达6小时增高,24小时达到高峰;E-选择素表达6小时达高峰,以后逐渐下降,24小时后降至对照组相同水平.脓毒症组肺VEC随着制模时间的延长,坏死和凋亡显著增加(P<0.01),电子显微镜观察也得到证实.结论:脓毒症大鼠肺ICAM-1和E-选择素的表达明显增加,可能导致肺VEC的坏死和凋亡以及急性肺损伤(ALI)和急性呼吸窘迫综合征(ARDS)的发生.     

Expression of leukocyte-endothelial cell adhesion molecules on monocyte adhesion to human endothelial cells on plasma treated PET and PTFE in vitro

We used a coculture model to evaluate the inflammatory potential of ammonia gas plasma modified PET and PTFE by flow cytometry and immunohistochemistry. In these studies, human endothelial cells from umbilical cord (HUVEC) and promonocytic U937 cells were used. HUVECs grown on polystyrene tissue culture coverslips and HUVECs stimulated with tumour necrosis factor (TNF-) were used as controls. U937 adhesion to endothelium on each surface was evaluated at day 1 and day 7. To further investigate the role of leukocyte–endothelial cell adhesion molecules (CAMs) in cell-to-cell interaction on material surfaces, the expression of the leukocyte–endothelial CAMs: ICAM-1, VCAM-1, PECAM-1, and E-selectin on HUVECs were evaluated after U937 cell adhesion. The results demonstrated that plasma treated PET (T-PET) and treated PTFE (T-PTFE) did not increase U937 cell adhesion compared to the negative control. Maximal adhesion of U937 cells to HUVEC was observed on TNF- stimulated endothelium with significant differences between day 1 and day 7, which is consistent with our prior observation that T-PET and T-PTFE did not cause HUVECs to increase the expression of adhesion molecules. After U937 cell adhesion, the expression of ICAM-1 and VCAM-1 of HUVECs were not different on T-PET and T-PTFE compared with the negative control. However, the expression of E-selectin was reduced on day 1, but not on day 7. The effects of plasma treated PET and PTFE on HUVEC adhesion and proliferation were also studied. On day 1 there were slight increases in the growth of HUVECs on both of T-PET and T-PTFE but this was not statistically significant. On day 7, the cell number increased significantly on the surfaces compared to the negative control. The results demonstrate that the plasma treatment of PET and PTFE with ammonia improves the adhesion and growth of endothelial cells and these surfaces do not exhibit a direct inflammatory effect in terms of monocyte adhesion and expression of leukocyte–endothelial CAMs. The monocyte adhesion to endothelial cells on surfaces can be used as a tool for the evaluation of material surface modification and further to study the mechanisms of cell-to-cell interactions in response to surfaces.