Shiga toxin-associated hemolytic uremic syndrome: combined cytotoxic effects of shiga toxin and lipopolysaccharide (endotoxin) on human vascular endothelial cells in vitro.

This study explores the in vitro relationship between Shiga toxin-producing Shigella spp. and Escherichia coli and the development of vascular complications in humans following bacillary dysentery. We propose that lipopolysaccharide (LPS; endotoxin) may combine with Shiga toxin to facilitate vascular damage characteristic of hemolytic uremic syndrome. We have examined the direct cytotoxic effects of Shiga toxin and LPS on human umbilical vein endothelial cells (HUVEC) in culture. Shiga toxin alone was cytotoxic to HUVEC, whereas LPS was noncytotoxic at concentrations at or below 10 micrograms/ml. Combinations of LPS with Shiga toxin resulted in a synergistic cytotoxic effect. The synergistic cytotoxic response of HUVEC to Shiga toxin plus LPS was dose dependent for both agents and was maximal at 24 h of exposure. This synergistic response was enhanced by preincubation of HUVEC with LPS. LPS (1 micrograms/ml) alone depressed HUVEC protein synthesis in a transient manner and enhanced the protein synthesis-inhibiting activity of Shiga toxin. The synergistic cytotoxic activity of LPS analogs was as follows, in decreasing order: complete LPS = diphosphoryl lipid A greater than monophosphoryl lipid A greater than deacylated LPS. These results are consistent with a role for Shiga toxin and LPS in the development of hemolytic uremic syndrome at the level of the vascular endothelium in humans.     

Shiga toxin-associated hemolytic-uremic syndrome: combined cytotoxic effects of Shiga toxin, interleukin-1 beta, and tumor necrosis factor alpha on human vascular endothelial cells in vitro.

This study explores the relationship between Shiga toxin-producing Shigella or Escherichia coli strains and the development of vascular complications in humans following bacillary dysentery. We propose that endotoxin-elicited interleukin-1 or tumor necrosis factor alpha (TNF) may combine with Shiga toxin to facilitate vascular damage characteristic of hemolytic-uremic syndrome. This study examines the cytotoxic effects of Shiga toxin, interleukin-1, and TNF on cultured human umbilical vein endothelial cells (HUVEC). Both Shiga toxin and TNF were cytotoxic to HUVEC, although HUVEC obtained from individual umbilical cords differed in their sensitivities to these agents. With Shiga toxin-sensitive HUVEC, combinations of TNF with Shiga toxin resulted in a synergistic cytotoxic effect. In contrast, interleukin-1 was not cytotoxic to HUVEC, nor did it enhance cell death in combination with Shiga toxin. The synergistic cytotoxic response of HUVEC to Shiga toxin and TNF was dose and time dependent for both agents and could be neutralized by monoclonal antibodies directed against either Shiga toxin or TNF. This synergistic response was delayed, being maximal on day 2. Preincubation (24 h) of HUVEC with TNF sensitized the cells to Shiga toxin. TNF alone had no effect on HUVEC protein synthesis but enhanced the inhibitory activity of Shiga toxin. These results are consistent with a role for Shiga toxin in the development of hemolytic-uremic syndrome at the level of the vascular endothelium in humans.     

Shiga toxin-associated hemolytic uremic syndrome: interleukin-1 beta enhancement of Shiga toxin cytotoxicity toward human vascular endothelial cells in vitro.

Development of hemolytic uremic syndrome (HUS) after infection by Shigella dysenteriae 1 or enterohemorrhagic Escherichia coli has been associated with the production of Shiga toxins (verotoxins). The putative target of Shiga toxins in HUS is the renal microvascular endothelium. This report shows that preincubation of human umbilical vein endothelial cells (HUVEC) with interleukin-1 beta (IL-1 beta) enhances the cytotoxic potency of Shiga toxin toward HUVEC. A preincubation of HUVEC with IL-1 beta is required for sensitization of HUVEC to Shiga toxin. Sensitization of HUVEC to Shiga toxin is IL-1 beta dose dependent. Development of the IL-1 beta response is time dependent, beginning within 2 h of IL-1 beta preincubation and increasing over the next 24 h. That these responses were due to IL-1 beta was demonstrated by heat inactivation of IL-1 beta, by neutralization of IL-1 beta by specific antibody, and by the ability of an IL-1 beta receptor antagonist to inhibit the effect of IL-1 beta. Shiga toxin-related inhibition of HUVEC protein synthesis preceded loss of cell viability. IL-1 beta incubation with HUVEC induced the receptor for Shiga toxin, globotriaosylceramide. Lipopolysaccharide included during IL-1 beta preincubation with HUVEC increased sensitivity to Shiga toxin in an additive manner. We conclude that IL-1 beta may induce Shiga toxin sensitivity in endothelial cells and contribute to the development of HUS.     

Effects of Cytotoxic Necrotizing Factor 1 and Lethal Toxin on Actin Cytoskeleton and VE-Cadherin Localization in Human Endothelial Cell Monolayers

Integrity of the vascular endothelium is largely dependent on endothelial cell shape and establishment of intercellular junctions. Certain pathogenic bacterial toxins alter the cytoskeletal architecture of intoxicated cells by modulating the GTPase activity of p21 Rho family proteins. In the present study we have analyzed the effect of Rho-directed toxins on the actin cytoskeleton and monolayer integrity of endothelial cells. We report here that Escherichia coli cytotoxic necrotizing factor 1 (CNF1) activates Rho in human umbilical vein endothelial cells (HUVEC). In confluent monolayers, CNF1 treatment induces prominent stress fiber formation without significantly modifying peripheral localization of VE-cadherin, a specific marker of vascular endothelial cell adherens junctions. Further, Rho activation with CNF1 blocks thrombin-induced redistribution of VE-cadherin staining and gap formation in HUVEC monolayers. Inhibition of Rho by prolonged treatment of cells with C3 exoenzyme (Clostridium botulinum) eliminates actin stress fibers without disrupting the continuity of VE-cadherin staining, indicating that Rho-dependent stress fibers are not required for maintaining this adhesion receptor at sites of intercellular contact. Lethal toxin (Clostridium sordellii), an inhibitor of Rac as well as Ras and Rap, potently disrupts the actin microfilament system and monolayer integrity in HUVEC cultures.     

Cytolethal distending toxin from Shiga toxin-producing Escherichia coli O157 causes irreversible G2/M arrest, inhibition of proliferation, and death of human endothelial cells

Recently, cytolethal distending toxin V (CDT-V), a new member of the CDT family, was identified in Shiga toxin-producing Escherichia coli (STEC) O157 and particular non-O157 serotypes. Here we investigated the biological effects of CDT-V from STEC O157:H(-) (strain 493/89) on human endothelial cells, which are believed to be major pathogenetic targets in severe STEC-mediated diseases. CDT-V caused dose-dependent G(2)/M cell cycle arrest leading to distension, inhibition of proliferation, and death in primary human umbilical vein endothelial cells (HUVEC) and two endothelial cell lines, EA.hy 926 cells (HUVEC derived) and human brain microvascular endothelial cells (HBMEC). The cell cycle effects of CDT-V were cell type specific. In HUVEC and EA.hy 926 cells, CDT-V caused a slowly developing but persistent G(2)/M block which resulted in delayed nonapoptotic cell death. In contrast, in HBMEC, CDT-V induced a rapidly evolving but transient G(2)/M block which was followed by progressive, mostly apoptotic cell death. In both HBMEC and EA.hy 926 cells, G(2)/M arrest was preceded by the early accumulation of a phosphorylated inactive form of cdc2 kinase. Significant G(2)/M arrest and inhibition of proliferation in both HUVEC and each of the endothelial cell lines were induced by 2 to 15 min of exposure to CDT-V, indicating that the effects of the toxin are irreversible. CDT-V-treated HBMEC and EA.hy 926 cells displayed fragmented nuclei and expressed phosphorylated histone protein H2AX, indicative of DNA damage followed by a DNA repair response. Our data demonstrate that CDT-V causes irreversible damage to human endothelial cells and thus may contribute to the pathogenesis of STEC-mediated diseases.     

Association of Mycobacterium leprae with human endothelial cells in vitro

Endothelial cell infection by Mycobacterium leprae has long been described histologically in all types of leprosy and in some of the acute reactions occurring in this disease. Recent evidence from experimental lepromatous neuritis indicates that M. leprae colonizes endothelial cells of epineural blood vessels even in sites of minimal infection, suggesting that interaction between these cells and M. leprae may play an important role in the selective localization of this organism to peripheral nerve. To begin to study the mechanisms involved, we have examined the interaction between M. leprae and human umbilical vein endothelial cells (HUVEC) in vitro using light microscopy, scanning and transmission electron microscopy, and confocal laser scanning microscopy. When M. leprae were added to confluent monolayers of HUVEC, uptake increased slowly to a maximum at 24 hours. Maximal percentages of infected cells were similar at ratios of organisms:cell over a range of 25:1 to 100:1. The bacilli appeared to lie within membrane-bound vacuoles at all time points. The kinetics of association of M. leprae with HUVEC are much slower than has previously been observed with macrophages, possibly due to differences in the binding of M. leprae. Compared with other pathogens that infect endothelial cells, M. leprae also appear to be ingested more slowly, and to a more limited degree. The receptors involved in M. leprae binding to endothelial cells and the impact of intracellular infection by M. leprae on these cells remain to be determined.     

Purification and some properties of a Vero toxin from Escherichia coli O157:H7 that is immunologically unrelated to Shiga toxin

A cytotoxin to Vero cells (Vero toxin) was purified from Escherichia coli O157:H7 isolated from a patient with hemorrhagic colitis by ammonium sulfate fractionation, DEAE-cellulose column chromatography, repeated chromatofocusing column chromatography and repeated high performance liquid chromatography. About 440 micrograms of purified Vero toxin was obtained from 12 liters of culture with a yield of about 22%. The purified Vero toxin showed similar cytotoxic activity to that of Shiga toxin to Vero cells and killed about 50% of the Vero cells at 1 pg. The activity was lost on heating the toxin at 80 degrees C for 10 minutes, but not at 60 degrees C for 10 minutes. The toxin also showed lethal toxicity to mice when injected intraperitoneally, the LD50 being 1 ng per mouse. The purified Vero toxin consisted of A and B subunits with molecular weights of about 35,000 and 10,700, respectively, which were slightly larger than those of Shiga toxin. On polyacrylamide gel disc electrophoresis, the mobility of the purified Vero toxin differed from that of Shiga toxin. The isoelectric point of the toxin was 4.1, which was also different from that of Shiga toxin (pI = 7.0). Furthermore, Vero toxin and Shiga toxin were found to be immunologically unrelated; anti-Vero toxin did not react with Shiga toxin, and similarly anti-Shiga toxin did not react with the Vero toxin in either the Ouchterlony double gel diffusion test or enzyme-linked immunosorbent assay. The Vero toxin purified in this work was found to be immunologically identical to VT2 and Shiga-like toxin II reported previously.     

Shiga toxins 1 and 2 translocate differently across polarized intestinal epithelial cells

Shiga toxin-producing Escherichia coli (STEC) is an important food-borne pathogen that causes hemolytic-uremic syndrome. Following ingestion, STEC cells colonize the intestine and produce Shiga toxins (Stx), which appear to translocate across the intestinal epithelium and subsequently reach sensitive endothelial cell beds. STEC cells produce one or both of two major toxins, Stx1 and Stx2. Stx2-producing STEC is more often associated with disease for reasons as yet undetermined. In this study, we used polarized intestinal epithelial cells grown on permeable filters as a model to compare Stx1 and Stx2 movement across the intestinal epithelium. We have previously shown that biologically active Stx1 is able to translocate across cell monolayers in an energy-dependent, saturable manner. This study demonstrates that biologically active Stx2 is also capable of movement across the epithelium without affecting barrier function, but significantly less Stx2 crossed monolayers than Stx1. Chilling the monolayers to 4 degrees C reduced the amount of Stx1 and Stx2 movement by 200-fold and 20-fold respectively. Stx1 movement was clearly directional, favoring an apical-to-basolateral translocation, whereas Stx2 movement was not. Colchicine reduced Stx1, but not Stx2, translocation. Monensin reduced the translocation of both toxins, but the effect was more pronounced with Stx1. Brefeldin A had no effect on either toxin. Excess unlabeled Stx1 blocks the movement of (125)I-Stx1. Excess Stx2 failed to have any effect on Stx1 movement. Our data suggests that, despite the many common physical and biochemical properties of the two toxins, they appear to be crossing the epithelial cell barrier by different pathways.     

p38 mitogen-activated protein kinase mediates lipopolysaccharide and tumor necrosis factor alpha induction of shiga toxin 2 sensitivity in human umbilical vein endothelial cells

Escherichia coli O157:H7 Shiga toxin 2 (Stx2), one of the causative agents of hemolytic-uremic syndrome, is toxic to endothelial cells, including primary cultured human umbilical vein endothelial cells (HUVEC). This sensitivity of cells to Stx2 can be increased with either lipopolysaccharide (LPS) or tumor necrosis factor alpha (TNF-α). The goal of the present study was to identify the intracellular signaling pathway(s) by which LPS and TNF-α sensitize HUVEC to the cytotoxic effects of Stx2. To identify these pathways, specific pharmacological inhibitors and small interfering RNAs were tested with cell viability endpoints. A time course and dose response experiment for HUVEC exposure to LPS and TNF-α showed that a relatively short exposure to either agonist was sufficient to sensitize the cells to Stx2 and that both agonists stimulated intracellular signaling pathways within a short time. Cell viability assays indicated that the p38 mitogen-activated protein kinase (MAPK) inhibitors SB202190 and SB203580 and the general protein synthesis inhibitor cycloheximide inhibited both the LPS and TNF-α sensitization of HUVEC to Stx2, while all other inhibitors tested did not inhibit this sensitization. Additionally, SB202190 reduced the cellular globotriaosylceramide content under LPS- and TNF-α-induced conditions. In conclusion, our results show that LPS and TNF-α induction of Stx2 sensitivity in HUVEC is mediated through a pathway that includes p38 MAPK. These results indicate that inhibition of p38 MAPK in endothelial cells may protect a host from the deleterious effects of Stx2.     

Shiga toxin-associated hemolytic uremic syndrome: effect of sodium butyrate on sensitivity of human umbilical vein endothelial cells to Shiga toxin.

Escherichia coli O157:H7-related vascular damage such as hemolytic uremic syndrome is believed to require the Shiga-like toxins. This study demonstrated that sodium butyrate sensitized human umbilical vein endothelial cells to Shiga toxin and increased the expression of Shiga toxin receptor, globotriaosylceramide (Gb3), on human umbilical vein endothelial cells.     

Insulin binding to microvascular endothelium of intact heart: a kinetic and morphometric analysis

We have studied insulin binding to blood vessels of the intact, beating heart. The beating hearts were perfused with [125I]iodoinsulin (3 X 10(-10) M) followed by perfusion with unlabeled insulin. The unlabeled insulin displaced the bound [125I]iodoinsulin in direct proportion to the concentration of the unlabeled hormone. Perfusion with unlabeled insulin at 10(-11) M elicited a significant displacement of [125I]iodoinsulin, with a maximal effect at 10(-6) M. Unlabeled proinsulin also displaced [125I]iodoinsulin in a dose-dependent manner, being 1% as potent as insulin. Perfusion with unrelated peptides had no effect. Radioautographic counting of 125I grains indicated that greater than 95% of the grain counts over blood vessels were within the microvessels. When [125I]iodoinsulin perfusion was followed by perfusion with unlabeled insulin at 10(-6) M, there was a 50% decrease in grain counts over the microvessels (versus perfusion with [125I]iodoinsulin alone); with coperfusion of [125I]iodoinsulin and 10(-6) M unlabeled insulin, an 80% decrease in grain counts occurred. Electron microscopic radioautography indicated that the 125I grains were associated with the vascular endothelial cells. We conclude that specific insulin receptors are present on endothelial cells of microvessels in the intact heart.     

Overexpression of stromal cell-derived factor-1 enhances endothelium-supported transmigration, maintenance, and proliferation of hematopoietic progenitor cells

To clarify the direct effects of aberrant overexpression of stromal cell-derived factor-1 (SDF-1) by the human endothelium on circulating progenitor cells, we overexpressed the SDF-1 gene in human umbilical vein endothelial cells using an adenoviral vector (HUVEC/AdeSDF-1) and examined the endothelium-supported trafficking and growth of hematopoietic progenitor cells (HPCs) in mobilized peripheral blood (mPB). In culture, the HUVEC/AdeSDF-1 monolayers induced the migration of mPB CD34(+) cells underneath the endothelium within a few hours, whereas HUVEC monolayers that expressed the LacZ gene (HUVEC/AdeLacZ) did not have this effect. In the Transwell system, the HUVEC/AdeSDF-1 cells supported a higher level of spontaneous transmigration of mPB CD34(+) cells than did the HUVEC/AdeLacZ cells. The co-culturing of mPB CD34(+) cells with HUVEC/ AdeSDF-1 cells led to a greater expansion of CD45(+) cells and colony-forming cells and reduced cellular apoptosis. Furthermore, the co-culturing of mPB CD34(+) cells with HUVEC/AdeSDF-1 cells led to the formation of numerous cobblestone-like areas, whereas co-cultures of mPB CD34(+) cells and HUVEC/AdeLacZ supported only a few cobblestone-like areas. These results indicate that SDF- 1 produced by endothelial cells plays an important role not only in the transmigration but also in the growth of HPCs that are in contact with endothelial cells. Our findings suggest that the enhanced expression and production of SDF-1 in the endothelium are essential steps for stem cell or progenitor cell recruitment to specific tissues and for the maintenance of these cells in situ.     

Cyclosporin A enhances the ability of trophoblasts to displace the activated human umbilical vein endothelial cell monolayers

Transformation of the spiral arteries including the displacement of vascular endothelial cells by extravillous trophoblasts is an essential prerequisite to normal placentation. However, the activated endothelial cells resist the invasion of trophoblasts, which contributes to the pathologies of some pregnant disorders. Our previous studies have demonstrated that Cyclosporin A (CsA) promotes the migration and invasion of human first-trimester trophoblasts. In the present study, we further investigated whether CsA could promote the ability of trophoblasts to displace the activated human umbilical vein endothelial cell (HUVEC) monolayers and the possible molecular mechanisms. Human choriocarcinoma Jar cells were used as a model of invasive trophoblasts. CsA pretreated JAR cells (red) were added to HUVEC monolayers (green) activated with either necrotic JAR cells or tumor necrosis factor alpha (TNFα). The ability of JAR cells to displace HUVECs from the monolayers was examined by confocal microscopy. The effects of CsA on Titin and E-cadherin expression, matrix metalloproteinases (MMPs) activity and CXCL12 secretion of JAR cells were evaluated by western blot, gelatin zymography and enzyme-linked immunosorbent assay (ELISA), respectively. We found that CsA pretreatment increased the ability of JAR cells to displace activated HUVECs from the monolayers. However, the displacement was reduced by untreated JAR cells. Moreover, CsA pretreatment up-regulated Titin expression, down-regulated E-cadherin expression, improved MMP2 and MMP9 activity, and increased the CXCL12 secretion in JAR cells. These results indicate that CsA may improve the trophoblast invasion to activated HUVEC monolayers through different downstream targets, and ultimately, improve the transformation and remodeling of spiral arteries.     

Cytotoxicity of Shiga toxin for primary cultures of human colonic and ileal epithelial cells.

Shiga toxin purified from Shigella dysenteriae 1 was cytotoxic to cultured epithelial cells from human colon and ileum. The cytotoxicity, which affected only about 50% of treated cells, was neutralized by rabbit antiserum monospecific for Shiga toxin and mediated by protein synthesis inhibition.     

Isolation of Shiga toxin-resistant Vero cells and their use for easy identification of the toxin.

Shiga toxin-resistant Vero cells were isolated by treatment of the cells with nitrosoguanidine. These mutant cells were not affected by Shiga toxin at more than 1 microgram/ml, although the parent Vero cells were sensitive to 25 pg of the toxin per ml. Immunofluorescence studies showed that all the mutant cells had lost toxin-binding capacity. The cytotoxic activities of various bacterial cultures against the parent and mutant cells were compared. All samples from 10 strains of Shigella dysenteriae type 1 and all three strains of Escherichia coli O157:H7 tested showed cytotoxicity to the parent cells but not to the mutant cells. Samples from other organisms, such as Shigella flexneri, Shigella sonnei, Clostridium difficile, Aeromonas hydrophila, Aeromonas sobria, and other E. coli strains, either had no effect or were cytotoxic on both the parent and mutant cells. Thus, these mutant cells could be used to identify Shiga-like toxin and distinguish it from other cytotoxins. The results also suggest the presence of a receptor for Shiga-like toxin on Vero cells that is essential for expression of the cytotoxicity of Shiga toxin but is not essential for growth of Vero cells.     

Effect of a specific cysteinyl leukotriene-receptor 1-antagonist (montelukast) on the transmigration of eosinophils across human umbilical vein endothelial cells

BACKGROUND: Leukotrienes have been implicated in the selective infiltration of eosinophils into the bronchial mucosa in asthma. OBJECTIVE: We studied whether eosinophil transmigration through cultured human umbilical vein endothelial cells (HUVECs) can be blocked by a specific cysteinyl LT1-receptor-antagonist. METHODS: Unstimulated and stimulated eosinophils from patients with asthma and normal controls were subjected to confluent human umbilical vein endothelial cell (HUVEC) monolayers separating the upper and lower chamber of Transwell culture plates. Unstimulated eosinophils or cells pre-incubated in the presence of the eosinophil activating cytokines GM-CSF or IL-13 were placed in the upper chambers while PAF, a potent chemoattractant factor for eosinophils, was added to the lower chamber. Migration of eosinophils was quantified by a beta-glucuronidase assay. RESULTS: The assumption that eosinophils express CysLT1 (cysteinyl-leukotriene 1)-receptors was based on our demonstration of mRNA-expression for the CysLT-1-receptor by polymerase chain reaction on purified eosinophils. The chemotactic response to PAF was significantly reduced when eosinophils were pre-incubated with montelukast for 15 min. When eosinophils were pre-incubated with GM-CSF and/or IL-13, the migratory response to PAF was also significantly reduced by montelukast. CONCLUSION: From these data we conclude that the specific cysteinyl LT1-receptor antagonist montelukast can inhibit PAF-induced eosinophil transmigration through cultured HUVEC monolayers.     

Effects of ionizing radiation on the adhesive interaction of human tumor and endothelial cells in vitro

A centrifugation assay was used to determine the effects of ionizing radiation on the adhesive interaction of A549 human lung adenocarcinoma tumor cells and human umbilical vein endothelial cells (HUVEC). The tumor cells were fluorescently labeled and divided into control (sham-irradiated) and irradiated groups. The irradiated groups were exposed to irradiation levels ranging from 5 to 20 Gy using a Cs source. A specified number of these A549 tumor cells were then delivered into each well of 96-well cell culture plates containing confluent monolayers of human umbilical cord vein endothelial cells (HUVEC), and were given time to adhere to the endothelial cells. The wells were then sealed and were exposed to an acceleration field varying from 1 to 42 g (0-500 rpm) for 10 min. Finally, the wells were drained, and the number of tumor cells adhering to the endothelial monolayer were counted using a fluorescent microscope system. Our results indicate that the irradiation of A549 tumor cells significantly increased their adhesive interaction with endothelial cells (number of adhering irradiated cells/number of adhering control cells = 1.0, 1.3, 1.9, 2.2 for 0, 5, 10, 20 Gy respectively). In contrast, when endothelial cells were irradiated, rather than tumor cells, adhesive interaction decreased with an increase in the radiation dose (irradiated/control = 1.0, 0.9, 0. 8, 0.5 for 0, 5, 10, 20 Gy respectively). Simultaneous irradiation of both the tumor cells and the endothelial cells did not alter their adhesive interaction significantly. These findings may have important implications for the metastatic ability of irradiated tumor cells.     

Activation of human vascular endothelial cells by IFN-gamma: acquisition of HLA class II expression, TSST-1-binding activity and accessory activity in T cell activation by the toxin.

Human umbilical vascular endothelial cells (HUVEC) stimulated with recombinant human IFN-gamma were investigated for expression of HLA class II molecules, toxic shock syndrome toxin-1 (TSST-1)-binding activity and accessory cell (AC) activity in TSST-1-induced T cell activation. HUVEC stimulated with recombinant human IFN-gamma ranging from 10 to 1,000 units/ml for 72 h express HLA class II molecules. Intensity of the expression was dependent on the concentration of IFN-gamma. HUVEC stimulated with 1,000 units/ml of IFN-gamma for 72 h exhibited 125I-TSST-1-binding that was blocked by the unlabeled toxin and monoclonal antibodies (mAb) to DR/DP. The activity was not removed by paraformaldehyde fixation. The IFN-gamma-stimulated HUVEC exhibited AC activity in TSST-1-induced IL-2 production by T cells from human peripheral blood mononuclear cells. The activity was blocked by mAb to DR. The above two activities were also observed in L cells transfected with DR2 genes but not in the unstimulated HUVEC and control L cells. In view of the fact that TSST-1 binds directly to HLA class II molecules and activates human T cells in association with HLA class II molecules on AC, it is likely that the acquisition of TSST-1-binding activity and AC activity in the toxin-induced T cell activation is mediated by the expression of HLA class II molecules. Vascular endothelial cells may play an important role in the development of pathological changes in TSS patients.     

Evaluation of a model for post-partum arthritis and the role of oestrogen in prevention of MRL-lpr associated rheumatic conditions.

Binding of both proteinase 3 (PR3) and myeloperoxidase (MPO) to endothelial cells (EC) has been suggested to be involved in the vascular damage seen in patients with Wegener's granulomatosis or microscopic polyangiitis. In the present study we investigated in detail the interaction of MPO and PR3 with cultured human umbilical vein endothelial cells (HUVEC) and its matrix products. In addition, we investigated whether interaction of PR3 or MPO with HUVEC monolayers also resulted in antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by anti-neutrophil cytoplasmic antibody (ANCA)-positive patient sera or rabbit IgG anti-PR3 or anti-MPO. Preincubation of HUVEC monolayers with PR3 or MPO resulted in a dose-dependent binding of both PR3 and MPO. However, HUVEC, preincubated with PR3 or MPO, followed by ANCA or by rabbit anti-PR3 or anti-MPO, were not susceptible to ADCC. Detailed analysis of the binding of PR3 to HUVEC monolayers showed that PR3 binds primarily to the extracellular matrix of endothelial cells, and to a very limited extent to the cells themselves. For MPO it was shown that it binds both to the extracellular matrix and to the endothelial cells themselves. However, after binding to HUVEC cultures, MPO was not detectable by polyclonal rabbit or human antibodies specific for MPO, probably because MPO is bound to sites not accessible for immunoglobulins. Binding of PR3 to HUVEC cultures (cells + matrix) was inhibited by fetal calf serum and by alpha 1-antitrypsin, but inactivation of enzymatic activity of PR3 by PMSF did not influence binding of PR3 to HUVEC cultures. Binding of MPO to HUVEC cultures was not influenced by fetal calf serum.     

原代人脐静脉内皮细胞分离和培养方法的改进

目的建立一套高效、方便、可靠的脐静脉内皮细胞的体外分离和培养方法。方法取剖腹产新生婴儿脐带,加入Ⅰ型胶原酶消化分离人脐静脉内皮细胞,内皮专用培养基EGM-2培养传代。应用相差显微镜观察细胞形态。DiL-Ac-LDL染色证实细胞具有内皮功能。免疫荧光染色证明新分离细胞表达FⅧ相关抗原。流式细胞仪检测细胞表面表达CD31。结果原代培养细胞培养10～15d左右长成单层,细胞呈多角形,铺路石样排列。DiL-Ac-LDL染色阳性,证实细胞具内皮吞噬功能。免疫荧光检测证明细胞特异性表达FⅧ相关抗原。流式细胞仪检测证明细胞表面高表达CD31。结论通过酶灌注法消化脐静脉血管获得细胞,操作简便、高效,EGM-2培养基可保证内皮细胞具有较高纯度,细胞形态学观察和细胞生物学鉴定证明获得人脐静脉血管内皮细胞。