Endothelial DNA Damage Research Articles

Nano-metal–organic-frameworks for treating H2O2-Secreting bacteria alleviate pulmonary injury and prevent systemic sepsis

As a vital bacteria-secreted toxin, hydrogen peroxide (H2O2) can destroy infected tissues and increase vascular permeability, leading to life-threatening systemic bacteremia or sepsis. No strategy that can alleviate H2O2-induced injury and prevent systemic sepsis has been reported. Herein, as a proof of concept, we demonstrate the use of H2O2-reactive metal-organic framework nanosystems (MOFs) for treating H2O2-secreting bacteria. In mice infected with Streptococcus pneumoniae (S. pneumoniae) isolated from patients, MOFs efficiently accumulate in the lungs after systemic administration due to infection-induced alveolar-capillary barrier dysfunction. Moreover, MOFs sequester pneumococcal H2O2, reduce endothelial DNA damage, and prevent systemic dissemination of bacteria. In addition, this nanosystem exhibits excellent chemodynamic bactericidal effects against drug-resistant bacteria. Through synergistic therapy with the antibiotic ampicillin, MOFs eliminate over 98% of invading S. pneumoniae, resulting in a survival rate of greater than 90% in mice infected with a lethal dose of S. pneumoniae. This work opens up new paths for the clinical treatment of toxin-secreting bacteria.

MFGE8 mitigates brain injury in a rat model of SAH by maintaining vascular endothelial integrity via TIGβ5/PI3K/CXCL12 signaling.

Leaked blood components, injured endothelial cells, local inflammatory response and vasospasm may converge to promote microthrombosis following subarachnoid hemorrhage (SAH). Previously, we showed that the milk fat globule-epidermal growth factor 8 (MFGE8) can mitigate SAH-induced microthrombosis. This present study was aimed to explore the molecular pathway participated in MFGE8-dependent protection on vascular endothelium. Immunofluorescence, immunoblot and behavioral tests were used to determine the molecular partner and signaling pathway mediating the effect of MFGE8 in vascular endothelium in rats with experimental SAH and controls, together with the applications of RNA silencing and pharmacological intervention methods. Relative to control, recombinant human MFGE8 (rhMFGE8) treatment increased 5-bromo-2'-deoxyuridine (BrdU) labeled new endothelial cells, reduced TUNUL-positive endothelial cells and elevated the expression of phosphatidylinositol 3-kinase (PI3K) and chemokine (C-X-C motif) ligand 12 (CXCL12), in the brains of SAH rats. These effects were reversed by MFGE8 RNA silencing, as well as following cilengitide and wortmannin intervention. These results suggest that MFGE8 promotes endothelial regeneration and mitigates endothelial DNA damage through the activation of the TIGβ5/PI3K/CXCL12 signaling pathway.

Local endothelial DNA repair deficiency causes aging-resembling endothelial-specific dysfunction.

We previously identified genomic instability as a causative factor for vascular aging. In the present study, we determined which vascular aging outcomes are due to local endothelial DNA damage, which was accomplished by genetic removal of ERCC1 (excision repair cross-complementation group 1) DNA repair in mice (EC-knockout (EC-KO) mice). EC-KO showed a progressive decrease in microvascular dilation of the skin, increased microvascular leakage in the kidney, decreased lung perfusion, and increased aortic stiffness compared with wild-type (WT). EC-KO showed expression of DNA damage and potential senescence marker p21 exclusively in the endothelium, as demonstrated in aorta. Also the kidney showed p21-positive cells. Vasodilator responses measured in organ baths were decreased in aorta, iliac and coronary artery EC-KO compared with WT, of which coronary artery was the earliest to be affected. Nitric oxide-mediated endothelium-dependent vasodilation was abolished in aorta and coronary artery, whereas endothelium-derived hyperpolarization and responses to exogenous nitric oxide (NO) were intact. EC-KO showed increased superoxide production compared with WT, as measured in lung tissue, rich in endothelial cells (ECs). Arterial systolic blood pressure (BP) was increased at 3 months, but normal at 5 months, at which age cardiac output (CO) was decreased. Since no further signs of cardiac dysfunction were detected, this decrease might be an adaptation to prevent an increase in BP. In summary, a selective DNA repair defect in the endothelium produces features of age-related endothelial dysfunction, largely attributed to loss of endothelium-derived NO. Increased superoxide generation might contribute to the observed changes affecting end organ perfusion, as demonstrated in kidney and lung.

MiR-103 promotes endothelial maladaptation by targeting lncWDR59

Blood flow at arterial bifurcations and curvatures is naturally disturbed. Endothelial cells (ECs) fail to adapt to disturbed flow, which transcriptionally direct ECs toward a maladapted phenotype, characterized by chronic regeneration of injured ECs. MicroRNAs (miRNAs) can regulate EC maladaptation through targeting of protein-coding RNAs. However, long noncoding RNAs (lncRNAs), known epigenetic regulators of biological processes, can also be miRNA targets, but their contribution on EC maladaptation is unclear. Here we show that hyperlipidemia- and oxLDL-induced upregulation of miR-103 inhibits EC proliferation and promotes endothelial DNA damage through targeting of novel lncWDR59. MiR-103 impedes lncWDR59 interaction with Notch1-inhibitor Numb, therefore affecting Notch1-induced EC proliferation. Moreover, miR-103 increases the susceptibility of proliferating ECs to oxLDL-induced mitotic aberrations, characterized by an increased micronucleic formation and DNA damage accumulation, by affecting Notch1-related β-catenin co-activation. Collectively, these data indicate that miR-103 programs ECs toward a maladapted phenotype through targeting of lncWDR59, which may promote atherosclerosis.

DNA damage response and senescence in endothelial cells of human cerebral cortex and relation to Alzheimer's neuropathology progression: a population-based study in the Medical Research Council Cognitive Function and Ageing Study (MRC-CFAS) cohort.

Abnormalities of the brain microvasculature in Alzheimer's disease have led to the vascular hypothesis of the disease, which predicts that vascular changes precede neuronal dysfunction and degeneration. To determine the spectrum of endothelial injury in the elderly and its relation to Alzheimer-type neuropathology we investigated DNA damage in a population-based sample derived from the Medical Research Council Cognitive Function and Ageing Study. We examined endothelial damage in frontal and temporal cortex (n = 97) using immunohistochemistry for γH2AX and DNA-protein kinase (DNA-PKcs). To determine the effects of endothelial DNA damage at the earliest stages of Alzheimer's pathology we further focused our analysis on cases classified as Braak 0-II and examined endothelial senescence using histochemistry for β-galactosidase and the expression of genes related to DNA damage and senescence using quantitative polymerase chain reaction (qPCR). We demonstrated large variation in endothelial DNA damage which was not associated with Alzheimer's neuropathology. Endothelial DNA-PKcs correlated with neuronal and glial DNA-PKcs counts. Focusing our further analysis on Braak 0-II cases, qPCR analysis demonstrated a trend to increased TP53 (P = 0.064) in cases with high compared with low endothelial DNA damage which was supported by immunohistochemical analysis of p53. Endothelial β-galactosidase expression was associated with increased neuronal (P = 0.033) and glial (P = 0.038), but not endothelial DNA-PKcs expression. Damage to brain endothelial cells occurs early in relation to, or independently of, Alzheimer pathology, and parallels that in neurones and glia. Endothelial DNA damage and senescence are a brain ageing process that may contribute to dysfunction of the neurovascular unit in some elderly individuals.

LOX-1 Receptor Blockade Abrogates oxLDL-induced Oxidative DNA Damage and Prevents Activation of the Transcriptional Repressor Oct-1 in Human Coronary Arterial Endothelium

Activation of the lectin-like oxLDL receptor (LOX-1) promotes atherosclerosis. Oxidized LDL (oxLDL) increases production of reactive oxygen species (ROS) and leads to the development of endothelial dysfunction. The molecular causes for oxLDL to induce oxidative DNA damage and metabolic dysfunction remain uncertain. Here we report treatment of cultured human coronary arterial endothelial cells (HCAEC) with oxLDL to cause oxidative DNA damage as determined by a 3-fold increase in 8-OH-desoxyguanosine adduct formation and a 4-fold induction of the growth arrest and DNA damage-inducible transcripts GADD45 and GADD153. Oxidative stress resulted in activation of Oct-1, a transcriptional repressor of various vascular cytochrome P450 (CYP) monooxygenases. Activation of Oct-1 was protein kinase C (PKC)-mediated. Binding of Oct-1 to promoter sequences of CYP monooxygenases was increased upon treatment of HCAEC with oxLDL. This resulted in repressed production of endothelium-derived hyperpolarization factor 11,12-epoxyeicosatrieonic acid. Small interference RNA-mediated functional knockdown of Oct-1 prevented oxLDL-mediated silencing of CYP expression. Inhibition of LOX-1 attenuated oxLDL-mediated endothelial DNA damage, Oct-1/DNA binding, and reversed impaired production of EDHF. Taken collectively, oxLDL induced oxidative DNA damage and activation of Oct-1 to result in metabolic dysfunction of coronary arterial endothelium.