Titanium dioxide nanoparticles impair the inner blood-retinal barrier and retinal electrophysiology through rapid ADAM17 activation and claudin-5 degradation

Abstract Background Depending on their distinct properties, titanium dioxide nanoparticles (TiO2-NPs) are manufactured extensively and widely present in our daily necessities, with growing environmental release and public concerns. In sunscreen formulations, supplementation of TiO2-NPs may reach up to 25% (w/w). Ocular contact with TiO2-NPs may occur accidentally in certain cases, allowing undesirable risks to human vision. This study aimed to understand the barrier integrity of retinal endothelial cells in response to TiO2-NP exposure. bEnd.3 cells and human retinal endothelial cells (HRECs) were exposed to TiO2-NP, followed by examination of their tight junction components and functions. Results TiO2-NP treatment apparently induced a broken structure of the junctional plaques, conferring decreased transendothelial electrical resistance, a permeable paracellular cleft, and improved cell migration in vitro. This might involve rapid activation of metalloproteinase, a disintegrin and metalloproteinase 17 (ADAM17), and ADAM17-mediated claudin-5 degradation. For the in vivo study, C57BL/6 mice were administered a single dose of TiO2-NP intravitreally and then subjected to a complete ophthalmology examination. Fluorescein leakage and reduced blood flow at the optical disc indicated a damaged inner blood-retinal barrier induced by TiO2-NPs. Inappreciable change in the thickness of retinal sublayers and alleviated electroretinography amplitude were observed in the TiO2-NP-treated eyes. Conclusions Overall, our data demonstrate that TiO2-NP can damage endothelial cell function, thereby affecting retinal electrophysiology.

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Abstract 16761: Long Non-coding RNA Meg3 Controls Endothelial Cell Function: Implications for Endothelial Aging and Senescence (Best of Basic Science Abstract)

Circulation ◽

10.1161/circ.132.suppl_3.16761 ◽

2015 ◽

Vol 132 (suppl_3) ◽

Author(s):

Reinier Boon ◽

Patrick Hofmann ◽

Katharina Michalik ◽

Andrea Knau ◽

Yuliya Ponomareva ◽

...

Keyword(s):

Gene Expression ◽

Endothelial Cells ◽

Cell Function ◽

Regulation Of Gene Expression ◽

Limb Ischemia ◽

Loss Of Function ◽

Endothelial Cell Function ◽

Aged Mice

The majority of transcribed RNA does not encode proteins, but may function as regulatory RNA. Long non-coding RNAs (lncRNAs) have been described to play an important role in many biological processes, including epigenetic regulation of gene expression. To determine the expression and functional role of lncRNAs in endothelial cells, we performed RNA deep sequencing of human umbilical venous endothelial cells (ECs). Among the highest expressed lncRNAs, we identified Meg3 (35.3±0.6 RPKM), which was increased in replicative senescent HUVECs in vitro (passage 16/17 vs 2/3, 2.9±0.99-fold). Interestingly, Meg3 is induced in the intima of aged mice and correlates with age in human hearts (p=0.016). In HUVECs, Meg3 localizes to the nucleus and is also induced by hypoxia (4.08±0.78-fold, p<0.05). Silencing of Meg3 using LNA-GapmeRs induced angiogenic sprouting and proliferation of endothelial cells in vitro (1.4±0.14-fold, P<0.05) and repressed SA-β-galactosidase activity. Conversely, lentiviral overexpression of Meg3 inhibited sprouting angiogenesis and cell cycle progression, although splicing isoforms of Meg3 show differential effects. Mechanistically, RNA immunoprecipitation showed that Meg3 associates specifically to H3K27me3, a silencing chromatin mark, and interacts with EZH2, a histone methyl transferase. Silencing of Meg3 in HUVECs represses, and overexpression of Meg3 induces, global gene expression, as measured by exon array analysis. As Meg3 was described to recruit Jarid2 to chromatin, we determined whether Meg3 requires Jarid2. The Meg3 loss-of-function induced repression of proliferation was normalized after silencing Jarid2, indicating that Meg3 effects are at least partly Jarid2-dependent. Finally, silencing of Meg3 in aged mice in vivo using gapmeRs in combination with hind limb ischemia significantly repressed Meg3 levels in the hindlimb and induced recovery of perfusion compared to control mice. Capillary and arteriole density was also markedly induced after silencing Meg3. These results demonstrate that silencing Meg3 may be a potential strategy to reduce endothelial senescence or increase regenerative angiogenesis.

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The Cytoplasmic Actins in the Regulation of Endothelial Cell Function

International Journal of Molecular Sciences ◽

10.3390/ijms22157836 ◽

2021 ◽

Vol 22 (15) ◽

pp. 7836

Author(s):

Vera B. Dugina ◽

Galina S. Shagieva ◽

Anton S. Shakhov ◽

Irina B. Alieva

Keyword(s):

Endothelial Cells ◽

Actin Cytoskeleton ◽

Spatial Organization ◽

Cell Function ◽

Cell Types ◽

Structural Basis ◽

Endothelial Cell Function ◽

Vascular Walls

The primary function of the endothelial cells (EC) lining the inner surface of all vessels is to regulate permeability of vascular walls and to control exchange between circulating blood and tissue fluids of organs. The EC actin cytoskeleton plays a crucial role in maintaining endothelial barrier function. Actin cytoskeleton reorganization result in EC contraction and provides a structural basis for the increase in vascular permeability, which is typical for many diseases. Actin cytoskeleton in non-muscle cells presented two actin isoforms: non-muscle β-cytoplasmic and γ-cytoplasmic actins (β-actins and γ-actins), which are encoded by ACTB and ACTG1 genes, respectively. They are ubiquitously expressed in the different cells in vivo and in vitro and the β/γ-actin ratio depends on the cell type. Both cytoplasmic actins are essential for cell survival, but they perform various functions in the interphase and cell division and play different roles in neoplastic transformation. In this review, we briefly summarize the research results of recent years and consider the features of the cytoplasmic actins: The spatial organization in close connection with their functional activity in different cell types by focusing on endothelial cells.

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Investigation of Wall Shear Stress in Cardiovascular Research and in Clinical Practice—From Bench to Bedside

International Journal of Molecular Sciences ◽

10.3390/ijms22115635 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5635

Author(s):

Katharina Urschel ◽

Miyuki Tauchi ◽

Stephan Achenbach ◽

Barbara Dietel

Keyword(s):

Endothelial Cells ◽

Shear Stress ◽

Wall Shear Stress ◽

Cell Function ◽

Computational Techniques ◽

Apical Surface ◽

Cardiovascular Research ◽

Endothelial Cell Function ◽

Wall Shear

In the 1900s, researchers established animal models experimentally to induce atherosclerosis by feeding them with a cholesterol-rich diet. It is now accepted that high circulating cholesterol is one of the main causes of atherosclerosis; however, plaque localization cannot be explained solely by hyperlipidemia. A tremendous amount of studies has demonstrated that hemodynamic forces modify endothelial athero-susceptibility phenotypes. Endothelial cells possess mechanosensors on the apical surface to detect a blood stream-induced force on the vessel wall, known as “wall shear stress (WSS)”, and induce cellular and molecular responses. Investigations to elucidate the mechanisms of this process are on-going: on the one hand, hemodynamics in complex vessel systems have been described in detail, owing to the recent progress in imaging and computational techniques. On the other hand, investigations using unique in vitro chamber systems with various flow applications have enhanced the understanding of WSS-induced changes in endothelial cell function and the involvement of the glycocalyx, the apical surface layer of endothelial cells, in this process. In the clinical setting, attempts have been made to measure WSS and/or glycocalyx degradation non-invasively, for the purpose of their diagnostic utilization. An increasing body of evidence shows that WSS, as well as serum glycocalyx components, can serve as a predicting factor for atherosclerosis development and, most importantly, for the rupture of plaques in patients with high risk of coronary heart disease.

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Quercetin and Idebenone Ameliorate Oxidative Stress, Inflammation, DNA damage, and Apoptosis Induced by Titanium Dioxide Nanoparticles in Rat Liver

Dose-Response ◽

10.1177/1559325818812188 ◽

2018 ◽

Vol 16 (4) ◽

pp. 155932581881218 ◽

Cited By ~ 10

Author(s):

Laila M. Fadda ◽

Hanan Hagar ◽

Azza M. Mohamed ◽

Hanaa M. Ali

Keyword(s):

Titanium Dioxide ◽

Histopathological Examination ◽

Titanium Dioxide Nanoparticles ◽

Reactive Protein ◽

Wide Range ◽

Factor Α ◽

Immunoglobin G ◽

Endothelial Growth Factor

Titanium dioxide nanoparticles (TiO2-NPs) are extensively used in a wide range of applications; however, many reports have investigated their nanotoxicological effect at the molecular level either in vitro or in vivo systems. The defensive roles of quercetin (Qur) or idebenone (Id) against the hepatotoxicity induced by TiO2-NPs were evaluated in the current study. The results showed that the coadministration of Qur or Id to rats intoxicated with TiO2-NPs markedly ameliorated the elevation in hepatic malondialdehyde (MDA), serum alanine amino-transferase (ALT), glucose, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), immunoglobin G (IgG), and C-reactive protein (CRP) levels compared to their levels in TiO2-NPs-treated rats. The aforementioned antioxidants also effectively modulated the changes in the levels of serum vascular endothelial growth factor (VEGF), nitric oxide (NO), hepatic DNA breakage, caspase-3, and inhibition of drug metabolizing enzymes (cytochrome P450s; CYP4502E12E1) in rat livers induced by TiO2-NPs toxicity. The histopathological examination of the liver section showed that TiO2-NPs caused severe degeneration of most hepatocytes with an increase in collagen in the portal region, while treatment with the antioxidants in question improved liver architecture. These outcomes supported the use of Qur and Id as protective agents against the hepatotoxicity induced by TiO2-NPs and other hepatotoxic drugs.

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Abstract 101: MiR-4260 Promotes the Proliferation, Migration, and Tube Formation of Human Umbilical Vein Endothelial Cells

Circulation Research ◽

10.1161/res.117.suppl_1.101 ◽

2015 ◽

Vol 117 (suppl_1) ◽

Author(s):

Qi Sun ◽

Dongcao Lv ◽

Qiulian Zhou ◽

Yihua Bei ◽

Junjie Xiao

Keyword(s):

Endothelial Cells ◽

Target Genes ◽

Cell Function ◽

Umbilical Vein ◽

Tube Formation ◽

Endothelial Cell Function ◽

Human Umbilical Vein ◽

And Migration ◽

Umbilical Vein Endothelial Cells

MicroRNAs (miRNAs, miRs), endogenous small non-coding RNA, have been shown to act as essential regulators in angiogenesis which plays important roles in improving blood flow and cardiac function following myocardial infarction. The current study investigated the potential of miR-4260 in endothelial cell function and angiogenesis using human umbilical vein endothelial cells (HUVEC). Our data demonstrated that overexpression of miR-4260 was associated with increased proliferation and migration of HUVEC using EdU incorporation assay (17.25%±1.31 vs 25.78%±1.24 in nc-mimics vs miR-4260 mimics, respectively) and wound healing assay, respectively. While downregulation of miR-4260 inhibited the proliferation (17.90%±1.37 vs 10.66%±1.41 in nc-inhibitor vs miR-4260 inhibitor, respectively) and migration of HUVEC. Furthermore, we found that miR-4260 mimics increased (129.75±3.68 vs 147±3.13 in nc-mimics vs miR-4260 mimics, respectively), while miR-4260 inhibitor decreased the tube formation of HUVECs in vitro (123.25±2.17 vs 92±4.45 in nc-inhibitor vs miR-4260 inhibitor expression, respectively). Our data indicate that miR-4260 contributes to the proliferation, migration and tube formation of endothelial cells, and might be essential regulators for angiogenesis. Further study is needed to investigate the underlying mechanism that mediates the role of miR-4260 in angiogenesis by identifying its putative downstream target genes.

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Exploration of cytotoxic and genotoxic endpoints following sub-chronic oral exposure to titanium dioxide nanoparticles

Toxicology and Industrial Health ◽

10.1177/0748233719879611 ◽

2019 ◽

Vol 35 (9) ◽

pp. 577-592 ◽

Cited By ~ 5

Author(s):

Srijita Chakrabarti ◽

Danswrang Goyary ◽

Sanjeev Karmakar ◽

Pronobesh Chattopadhyay

Keyword(s):

Titanium Dioxide ◽

Titanium Dioxide Nanoparticles ◽

Flow Cytometric Analysis ◽

Raw 264.7 Cells ◽

Oral Exposure ◽

Chromosomal Breakage ◽

Flow Cytometric ◽

Higher Doses

Health hazards of titanium dioxide nanoparticles (TiO2-NPs) have raised severe concerns because of the paucity of information regarding the toxic effects among the population. In the present research, the in vitro and in vivo cytotoxic potential of TiO2-NPs were evaluated using flow cytometric techniques. Further, in vitro and in vivo genotoxic endpoints were estimated by means of comet, micronucleus (MN), and chromosomal aberration (CA) assays. In vitro analysis was performed at the concentration range of 10–100 µg/mL using murine RAW 264.7 cells. In vivo experiments were conducted on Albino mice (M/F) by exposing them to 200 and 500 mg/kg TiO2-NPs for 90 days. Decreased percentage of cell viability with higher doses of TiO2-NPs was evident in both in vitro and in vivo flow cytometric analysis. Further, an impaired cell cycle (G0/G1, S, and G2/M) was reflected in the present investigation following the exposure to TiO2-NPs. Increased comet scores such as tail length, % DNA in tail, tail moment, and olive moment were also observed with the higher doses of TiO2-NPs in vitro and in vivo comet assays. Finally, the in vivo MN and CA assays revealed the formation of MN and chromosomal breakage following the exposure to TiO2-NPs.

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Agglomeration of titanium dioxide nanoparticles increases toxicological responses in vitro and in vivo

Particle and Fibre Toxicology ◽

10.1186/s12989-020-00341-7 ◽

2020 ◽

Vol 17 (1) ◽

Cited By ~ 7

Author(s):

Sivakumar Murugadoss ◽

Frederic Brassinne ◽

Noham Sebaihi ◽

Jasmine Petry ◽

Stevan M. Cokic ◽

...

Keyword(s):

Titanium Dioxide ◽

Titanium Dioxide Nanoparticles

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Contribution of Natural Killer Cells to Inhibition of Angiogenesis by Interleukin-12

Blood ◽

10.1182/blood.v93.5.1612 ◽

1999 ◽

Vol 93 (5) ◽

pp. 1612-1621 ◽

Cited By ~ 127

Author(s):

Lei Yao ◽

Cecilia Sgadari ◽

Keizo Furuke ◽

Eda T. Bloom ◽

Julie Teruya-Feldstein ◽

...

Keyword(s):

Endothelial Cells ◽

Nk Cells ◽

Natural Killer ◽

Cell Function ◽

Nk Cell ◽

Primary Cultures ◽

Interleukin 12 ◽

Ifn Γ

Abstract Interleukin-12 (IL-12) inhibits angiogenesis in vivo by inducing interferon-γ (IFN-γ) and other downstream mediators. Here, we report that neutralization of natural killer (NK) cell function with antibodies to either asialo GM1 or NK 1.1 reversed IL-12 inhibition of basic fibroblast growth factor (bFGF)-induced angiogenesis in athymic mice. By immunohistochemistry, those sites where bFGF-induced neovascularization was inhibited by IL-12 displayed accumulation of NK cells and the presence of IP-10–positive cells. Based on expression of the cytolytic mediators perforin and granzyme B, the NK cells were locally activated. Experimental Burkitt lymphomas treated locally with IL-12 displayed tumor tissue necrosis, vascular damage, and NK-cell infiltration surrounding small vessels. After activation in vitro with IL-12, NK cells from nude mice became strongly cytotoxic for primary cultures of syngeneic aortic endothelial cells. Cytotoxicity was neutralized by antibodies to IFN-γ. These results document that NK cells are required mediators of angiogenesis inhibition by IL-12, and provide evidence that NK-cell cytotoxicity of endothelial cells is a potential mechanism by which IL-12 can suppress neovascularization.

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