scholarly journals Sitagliptin and the Blood-Retina Barrier: Effects on Retinal Endothelial Cells Manifested Only after Prolonged Exposure

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Anja Jäckle ◽  
Focke Ziemssen ◽  
Eva-Maria Kuhn ◽  
Jürgen Kampmeier ◽  
Gerhard K. Lang ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Prolonged Exposure ◽  
Diabetic Patients ◽  
Barrier Dysfunction ◽  
Fibronectin Receptor ◽  
Retinal Endothelial Cells ◽  
Junction Protein

Inhibitors of dipeptidyl peptidase-4 (DPP-4) are widely used to treat diabetes mellitus, but data concerning their effects on the barrier stability of retinal endothelial cells (REC) in vivo and in vitro are inconsistent. Therefore, we studied whether the barrier properties of immortalized endothelial cells of the bovine retina (iBREC) were affected by the inhibitors of DPP-4 sitagliptin (10-1000 nM) and diprotin A (1-25 μM). Their effects were also investigated in the presence of VEGF-A165 because diabetic patients often develop macular edema caused by VEGF-A-induced permeability of REC. To detect even transient or subtle changes of paracellular and transcellular flow as well as adhesion of the cells to the extracellular matrix, we continuously monitored the cell index (CI) of confluent iBREC grown on gold electrodes. Initially, the CI remained stable but started to decline significantly and persistently at 40 h or 55 h after addition of sitagliptin or diprotin A, respectively. Both inhibitors did not modulate, prevent, or revert the persistent VEGF-A165-induced reduction of the CI. Interestingly, sitagliptin and diprotin A increased the expression of the tight-junction protein claudin-1 which is an important component of a functional barrier formed by iBREC. In contrast, expressions of CD29—a subunit of the fibronectin receptor—or of the tetraspanin CD9 were lower after extended treatment with the DPP-4 inhibitors; less of the CD9 was seen at the plasma membrane after prolonged exposure to sitagliptin. Because both associated proteins are important for adhesion of iBREC to the extracellular matrix, the observed low CI might be caused by weakened attachment of the cells. From our results, we conclude that extended inhibition of DPP-4 destabilizes the barrier formed by microvascular REC and that DPP-4 inhibitors like sitagliptin do not counteract or enhance a VEGF-A165-induced barrier dysfunction as frequently observed in DME.

Desmopressin (DDAVP) Enhances Platelet Adhesion to the Extracellular Matrix of Cultured Human Endothelial Cells through Increased Expression of Tissue Factor

1997 ◽  
Vol 77 (05) ◽  
pp. 0975-0980 ◽  
Author(s):  
Angel Gálvez ◽  
Goretti Gómez-Ortiz ◽  
Maribel Díaz-Ricart ◽  
Ginés Escolar ◽  
Rogelio González-Sarmiento ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Tissue Factor ◽  
Platelet Adhesion ◽  
Umbilical Vein ◽  
Procoagulant Activity ◽  
Experimental Conditions ◽  
Chromogenic Assay

SummaryThe effect of desmopressin (DDAVP) on thrombogenicity, expression of tissue factor and procoagulant activity (PCA) of extracellular matrix (ECM) generated by human umbilical vein endothelial cells cultures (HUVEC), was studied under different experimental conditions. HUVEC were incubated with DDAVP (1, 5 and 30 ng/ml) and then detached from their ECM. The reactivity towards platelets of this ECM was tested in a perfusion system. Coverslips covered with DD A VP-treated ECMs were inserted in a parallel-plate chamber and exposed to normal blood anticoagulated with low molecular weight heparin (Fragmin®, 20 U/ml). Perfusions were run for 5 min at a shear rate of 800 s1. Deposition of platelets on ECMs was significantly increased with respect to control ECMs when DDAVP was used at 5 and 30 ng/ml (p <0.05 and p <0.01 respectively). The increase in platelet deposition was prevented by incubation of ECMs with an antibody against human tissue factor prior to perfusion. Immunofluorescence studies positively detected tissue factor antigen on DDAVP derived ECMs. A chromogenic assay performed under standardized conditions revealed a statistically significant increase in the procoagulant activity of the ECMs produced by ECs incubated with 30 ng/ml DDAVP (p <0.01 vs. control samples). Northern blot analysis revealed increased levels of tissue factor mRNA in extracts from ECs exposed to DDAVP. Our data indicate that DDAVP in vitro enhances platelet adhesion to the ECMs through increased expression of tissue factor. A similar increase in the expression of tissue factor might contribute to the in vivo hemostatic effect of DDAVP.

Interactions between mesoderm cells and the extracellular matrix following gastrulation in the chick embryo

1991 ◽  
Vol 99 (2) ◽  
pp. 431-441
Author(s):  
A.J. Brown ◽  
E.J. Sanders
Keyword(s):  
Extracellular Matrix ◽  
Chick Embryo ◽  
Basement Membrane ◽  
Primitive Streak ◽  
Cell Binding ◽  
Fab Fragment ◽  
Fibronectin Receptor ◽  
In Vitro Methods

In the gastrulating chick embryo, the mesoderm cells arise from the epiblast layer by ingression through the linear accumulation of cells called the primitive streak. The mesoderm cells emerge from the streak with a fibroblastic morphology and proceed to move away from the mid-line of the embryo using, as a substratum, the basement membrane of the overlying epiblast and the extracellular matrix. We have investigated the roles of fibronectin and laminin as putative substrata for mesoderm cells using complementary in vivo and in vitro methods. We have microinjected agents into the tissue space adjacent to the primitive streak of living embryos and, after further incubation, we have examined the embryos for perturbation of the mesoderm tissue. These agents were: cell-binding regions from fibronectin (RGDS) and laminin (YIGSR), antibodies to these glycoproteins, and a Fab' fragment of the antibody to fibronectin. We find that RGDS, antibody to fibronectin, and the Fab' fragment cause a decrease in the number of mesoderm cells spread on the basement membrane, and a perturbation of cell shape suggesting locomotory impairment. No such influence was seen with YIGSR or antibodies to laminin. These results were extended using in vitro methods in which mesoderm cells were cultured in fibronectin-free medium on fibronectin or laminin in the presence of various agents. These agents were: RGDS; YIGSR; antibodies to fibronectin, fibronectin receptor, laminin and vitronectin; and a Fab' fragment of the fibronectin antiserum. We find that cell attachment and spreading on fibronectin is impaired by RGDS, antiserum to fibronectin, the Fab' fragment of fibronectin antiserum, and antiserum to fibronectin receptor. The results suggest that although the RGDS site in fibronectin is important, it is probably not the only fibronectin cell-binding site involved in mediating the behaviour of the mesoderm cells. Cells growing on laminin were perturbed by YIGSR, RGDS and antibodies to laminin, suggesting that mesoderm cells are able to recognise at least two sites in the laminin molecule. We conclude that the in vivo dependence of mesoderm cells on fibronectin is confirmed, but that although these cells have the ability to recognise sites in laminin as mediators of attachment and spreading, the in vivo role of this molecule in mesoderm morphogenesis is not yet certain.

Interaction between vascular endothelial cells and vascular intimal spindle-shaped cells in vitro

1983 ◽  
Vol 60 (1) ◽  
pp. 89-102
Author(s):  
D de Bono ◽  
C. Green
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Vascular Endothelial Cells ◽  
Three Dimensional ◽  
Vascular Endothelial ◽  
Pure Cultures ◽  
Species Specific ◽  
Endothelial Growth Factor

The interactions between human or bovine vascular endothelial cells and fibroblast-like vascular intimal spindle-shaped cells have been studied in vitro, using species-specific antibodies to identify the different components in mixed cultures. Pure cultures of endothelial cells grow as uniform, nonoverlapping monolayers, but this growth pattern is lost after the addition of spindle cells, probably because the extracellular matrix secreted by the latter causes the endothelial cells to modify the way they are attached to the substrate. The result is a network of tubular aggregates of endothelial cells in a three-dimensional ‘polylayer’ of spindle-shaped cells. On the other hand, endothelial cells added to growth-inhibited cultures of spindle-shaped cells will grow in sheets over the surface of the culture. Human endothelial cells grown in contact with spindle-shaped cells have a reduced requirement for a brain-derived endothelial growth factor. The interactions of endothelial cells and other connective tissue cells in vitro may be relevant to the mechanisms of endothelial growth and blood vessel formation in vivo, and emphasize the potential importance of extracellular matrix in controlling endothelial cell behaviour.

Abstract 585: Endothelial Cells from Adipose Tissue of Obese Humans Display Mesenchymal Characteristics

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Bronson A Haynes ◽  
Eric J Lehrer ◽  
Giann J Bhatt ◽  
Ryan W Huyck ◽  
Ashley N James ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Adipose Tissue ◽  
Prolonged Exposure ◽  
Endothelial Permeability ◽  
Fold Increase ◽  
Atp Production ◽  
Functional Changes ◽  
Twist 1

The mechanisms underlying vascular dysfunction in adipose tissue (AT) in obesity are not clearly understood. Our hypothesis is that in response to pro-inflammatory cytokines (PIC) present in obese AT, endothelial cells (EC) can de-differentiate and acquire a mesenchymal-like phenotype (EndoMT) that leads to endothelial dysfunction. To test our hypothesis, we measured endothelial and mesenchymal markers of CD31 + CD34 + EC isolated from omental (OM) and subcutaneous (SC) AT of bariatric subjects (BAMVEC) using RT-PCR and western blot. Permeability and oxidative metabolism were determined by ECIS and Seahorse analyzer XF e 24, respectively. BAMVEC isolated from both OM and SC fat showed very low protein expression of vWF and VE-Cadherin (EC markers) and abundantly expressed αSMA and the EMT transcription factor twist-1. To determine effects of PIC on EndoMT, commercially available primary endothelial cells from AT (HAMVEC) were treated in vitro with PIC (2.5ng/mL TNFα, IFNγ and TGFβ) for 1, 3 or 6 days. We found progressive down-regulation by >2-fold (p<0.001) of the EC markers vWF, VE-Cadherin, and Occludin compared to controls. As early as 1 day of PIC treatment twist-1 (p<0.001) and snail1 (p<0.05) showed an increase by >2-fold. Similarly, OM and SC BAMVEC expressed >2-fold increase in the mesenchymal genes twist-1, FSP1, αSMA, and snail1 compared to untreated HAMVEC. Metabolically, BAMVEC had increased ATP production and maximal respiration compared to HAMVEC suggesting increased oxidative phosphorylation, a marker of mesenchymal-like cells. PIC stimulation of HAMVEC yielded significant increases in endothelial permeability and motility (p<0.001). Notably, there were no significant differences in any of the markers between OM and SC BAMVEC. These results show that EC in obese AT exhibit a mesenchymal-like phenotype which may account for functional changes such as increased permeability and migration and are not depot specific. Using primary EC from human AT we showed that prolonged exposure to PIC induces a phenotype similar to CD31+CD34+ EC from obese AT. This supports the concept that AT inflammation can promote EC de-differentiation in vivo and our in vitro model is suitable for future studies to uncover the relevant mechanisms.

scholarly journals Myeloperoxidase and Septic Conditions Disrupt Sphingolipid Homeostasis in Murine Brain Capillaries In Vivo and Immortalized Human Brain Endothelial Cells In Vitro

2020 ◽  
Vol 21 (3) ◽  
pp. 1143 ◽  
Author(s):  
Madeleine Goeritzer ◽  
Eva Bernhart ◽  
Ioanna Plastira ◽  
Helga Reicher ◽  
Christina Leopold ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Sickness Behavior ◽  
Brain Endothelial Cells ◽  
Brain Capillaries ◽  
Barrier Dysfunction ◽  
Pharmacological Inhibition ◽  
Regulated Gene Expression ◽  
The Impact

During inflammation, activated leukocytes release cytotoxic mediators that compromise blood–brain barrier (BBB) function. Under inflammatory conditions, myeloperoxidase (MPO) is critically involved in inflicting BBB damage. We used genetic and pharmacological approaches to investigate whether MPO induces aberrant lipid homeostasis at the BBB in a murine endotoxemia model. To corroborate findings in a human system we studied the impact of sera from sepsis and non-sepsis patients on brain endothelial cells (hCMEC/D3). In response to endotoxin, the fatty acid, ceramide, and sphingomyelin content of isolated mouse brain capillaries dropped and barrier dysfunction occurred. In mice, genetic deficiency or pharmacological inhibition of MPO abolished these alterations. Studies in metabolic cages revealed increased physical activity and less pronounced sickness behavior of MPO−/− compared to wild-type mice in response to sepsis. In hCMEC/D3 cells, exogenous tumor necrosis factor α (TNFα) potently regulated gene expression of pro-inflammatory cytokines and a set of genes involved in sphingolipid (SL) homeostasis. Notably, treatment of hCMEC/D3 cells with sera from septic patients reduced cellular ceramide concentrations and induced barrier and mitochondrial dysfunction. In summary, our in vivo and in vitro data revealed that inflammatory mediators including MPO, TNFα induce dysfunctional SL homeostasis in brain endothelial cells. Genetic and pharmacological inhibition of MPO attenuated endotoxin-induced alterations in SL homeostasis in vivo, highlighting the potential role of MPO as drug target to treat inflammation-induced brain dysfunction.

scholarly journals pVHL Function Is Essential for Endothelial Extracellular Matrix Deposition

2006 ◽  
Vol 26 (7) ◽  
pp. 2519-2530 ◽  
Author(s):  
Nan Tang ◽  
Fiona Mack ◽  
Volker H. Haase ◽  
M. Celeste Simon ◽  
Randall S. Johnson
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Critical Role ◽  
Matrix Assembly ◽  
Developmental Defects ◽  
Vhl Gene ◽  
Matrix Deposition ◽  
Fibronectin Deposition

ABSTRACT The tumor suppressor von Hippel-Lindau protein (pVHL) is critical for cellular molecular oxygen sensing, acting to target degradation of the hypoxia-inducible factor alpha transcription factor subunits under normoxic conditions. We have found that independent of its function in regulating hypoxic response, the VHL gene plays a critical role in embryonic endothelium development through regulation of vascular extracellular matrix assembly. We created mice lacking the VHL gene in endothelial cells; these conditional null mice died at the same stage as homozygous VHL-null mice, with similar vascular developmental defects. These included defective vasculogenesis in the placental labyrinth, a collapsed endocardium, and impaired vessel network patterning. The defects in embryonic vascularization were correlated with a diminished vascular fibronectin deposition in vivo and defective endothelial extracellular fibronectin assembly in vitro. We found that the impaired migration and adhesion of VHL-null endothelial cells can be partially rescued by the addition of back exogenous fibronectin, which indicates that pVHL regulation of fibronectin deposition plays an important functional role in vascular patterning and maintenance of vascular integrity.

scholarly journals Hyperglycemia downregulates Connexin36 in pancreatic islets via the upregulation of ICER-1/ICER-1γ

2013 ◽  
Vol 51 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Jacques-Antoine Haefliger ◽  
Françoise Rohner-Jeanrenaud ◽  
Dorothée Caille ◽  
Anne Charollais ◽  
Paolo Meda ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islets ◽  
Chronic Exposure ◽  
Prolonged Exposure ◽  
Mrna Levels ◽  
Adult Rats ◽  
Junction Protein ◽  
And Function

Channels formed by the gap junction protein Connexin36 (CX36) contribute to the proper control of insulin secretion. We previously demonstrated that chronic exposure to glucose decreases Cx36 levels in insulin-secreting cells in vitro. Here, we investigated whether hyperglycemia also regulates Cx36 in vivo. Using a model of continuous glucose infusion in adult rats, we showed that prolonged (24–48 h) hyperglycemia reduced the Cx36 gene Gjd2 mRNA levels in pancreatic islets. Accordingly, prolonged exposure to high glucose concentrations also reduced the expression and function of Cx36 in the rat insulin-producing INS-1E cell line. The glucose effect was blocked after inhibition of the cAMP/PKA pathway and was associated with an overexpression of the inducible cAMP early repressor ICER-1/ICER-1γ, which binds to a functional cAMP-response element in the promoter of the Cx36 gene Gjd2. The involvement of this repressor was further demonstrated using an antisense strategy of ICER-1 inhibition, which prevented glucose-induced downregulation of Cx36. The data indicate that chronic exposure to glucose alters the in vivo expression of Cx36 by the insulin-producing β-cells through ICER-1/ICER-1γ overexpression. This mechanism may contribute to the reduced glucose sensitivity and altered insulin secretion, which contribute to the pathophysiology of diabetes.

In vitro and in vivo wound healing-promoting activities of β-lapachone

2008 ◽  
Vol 295 (4) ◽  
pp. C931-C943 ◽  
Author(s):  
Hsiu-Ni Kung ◽  
Mei-Jun Yang ◽  
Chi-Fen Chang ◽  
Yat-Pang Chau ◽  
Kuo-Shyan Lu
Keyword(s):  
Wound Healing ◽  
Endothelial Cells ◽  
Healing Process ◽  
Cell Types ◽  
Underlying Mechanism ◽  
Mapk Signaling ◽  
Diabetic Patients ◽  
Impaired Wound Healing

Impaired wound healing is a serious problem for diabetic patients. Wound healing is a complex process that requires the cooperation of many cell types, including keratinocytes, fibroblasts, endothelial cells, and macrophages. β-Lapachone, a natural compound extracted from the bark of the lapacho tree ( Tabebuia avellanedae), is well known for its antitumor, antiinflammatory, and antineoplastic effects at different concentrations and conditions, but its effects on wound healing have not been studied. The purpose of the present study was to investigate the effects of β-lapachone on wound healing and its underlying mechanism. In the present study, we demonstrated that a low dose of β-lapachone enhanced the proliferation in several cells, facilitated the migration of mouse 3T3 fibroblasts and human endothelial EAhy926 cells through different MAPK signaling pathways, and accelerated scrape-wound healing in vitro. Application of ointment with or without β-lapachone to a punched wound in normal and diabetic ( db/ db) mice showed that the healing process was faster in β-lapachone-treated animals than in those treated with vehicle only. In addition, β-lapachone induced macrophages to release VEGF and EGF, which are beneficial for growth of many cells. Our results showed that β-lapachone can increase cell proliferation, including keratinocytes, fibroblasts, and endothelial cells, and migration of fibroblasts and endothelial cells and thus accelerate wound healing. Therefore, we suggest that β-lapachone may have potential for therapeutic use for wound healing.

EFFECTS OF 13-H0DE AND HETEs ON TUMOR CELL/ENDOTHELIAL CELL INTERACTIONS

1987 ◽  
Author(s):  
E Bastida ◽  
L Almirall
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Arachidonic Acid ◽  
Linoleic Acid ◽  
Cell Line ◽  
Hydroxyoctadecadienoic Acid ◽  
Adhesion Process ◽  
Stimulation Of

We and others reported that endothelial cells (ECs) convert linoleic acid into 13-hydroxyoctadecadienoic acid (13-H0DE) under basal conditions, and arachidonic acid into 15-hydroxyeicosatet-raenoic acid (15-HETE) following stimulation (1,2). We also reported that lipoxygenase metabolism influenced platelet (PLT) interactions with ECs, tumor cells (TCs) and extracellular matrix (BM) (1,3,4). Thus, we performed studies to determine i) if TCs also produce 13-H0DE and HETEs, and ii) the effect of TC and EC 13-H0DE and HETEs synthesis on TC/EC adhesion. We measured i) the ratios of 13-H0DE:HETE in 5TC lines, under basal and stimulated conditions, in metastatic and non-metastatic TCs of the same cell line, and TCs treated with salicylate (SAL) or dipyridamole (DIP), and ii) their relationships with TC adhesion to ECs and BM. 13-H0DE and HETEs were assayed by HPLC. TC adhesion was assayed as the # radiolabelled TCs adherent to ECs or BM. cAMP was assayed by RIA. Under basal conditions, TCs produced 13-H0DE and HETEs, the intracellular ratio of which markedly affected their adhesivity; e.g. the least adhesive TC (U87MG glioblastoma) produced 21Xs more 13-H0DE than HETE’s, while a more adhesive TC (A549, adenocarcinoma) produced 4Xs more HETEs than 13-H0DE. Non-metastatic TCs preferentially produced 13-H0DE while metastatic TCs of the same cell line, produced HETEs. Stimulation of TCs or ECs decreased 13-H0DE, and increased HETE synthesis and TC/EC adhesion. Inhibiting intracellular 13-H0DE synthesis in either TCs or EC (SAL RX) enhanced TC/EC and TC/BM adhesion. Enhancing 13-H0DE synthesis by elevating cAMP (DIP RX) inhibited TC/EC and TC/BM adhesion. We conclude that 1) in vitro TCs produce 13-H0DE and HETEs, 2) the ratio of 13-H0DE:HETEs in TCs and ECs affects their adhesivity; and 3) the ratio of intracellular 13-H0DE:HETEs depends upon cAMP. This suggests that 13-H0DE:HETE ratios in TCs and ECs influence the adhesion process in the pathogenesis of thrombosis and metastasis in vivo. (1) Buchanan et al, JBC 30:1985. (2) Hopkins et al, JBC 29:1984. (3) Bastida et al, Int. J. Cane. 1987. (4) Buchanan et al, Prost. Leuk. Med., 1986.

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