Aortic Endothelial Cells Research Articles

Itchy E3 Ubiquitin Ligase-Mediated Ubiquitination of Ferritin Light Chain Contributes to Endothelial Ferroptosis in Atherosclerosis

This research seeks to investigate the function and fundamental mechanisms of Itchy E3 ubiquitin ligase (ITCH), a HECT (homologous to E6AP carboxyl terminus)-type E3 ubiquitin ligase, in endothelial ferroptosis, particularly in the context of atherosclerosis, which has been underexplored. The levels of ITCH protein in the aortas of mice with atherosclerosis were analyzed. Constructs for ITCH RNA interference were generated and introduced into human aortic endothelial cells (HAECs). The findings indicated that ITCH protein expression was elevated in atherosclerotic mice and HAECs exposed to oxidized low-density lipoprotein (ox-LDL). ITCH downregulation significantly mitigated ox-LDL-induced endothelial injury and dysfunction. Reducing ITCH expression inhibited ox-LDL-induced endothelial ferroptosis. This study also revealed that ITCH mediates ox-LDL-induced ubiquitin-dependent degradation of ferritin light chain (FTL) in HAECs. The protective impact of ITCH knockdown against ox-LDL-induced ferroptosis and endothelial injury was reversed by FTL siRNA. Additionally, in vivo experiments showed that inhibiting ITCH reduced atherosclerosis progression and reversed ferroptosis in the aorta, with an associated increase in FTL protein expression in the aortas of mice. This study demonstrates that ITCH interacts with and regulates the stability of the FTL protein via the ubiquitin–proteasome system, contributing to ox-LDL-induced ferroptosis and endothelial cell dysfunction. Targeting components of the ITCH-FTL pathway holds potential as a therapeutic strategy against atherosclerosis.

IRF-1 Regulates Mitochondrial Respiration and Intrinsic Apoptosis Under Metabolic Stress through ATP Synthase Ancillary Factor TMEM70.

Mitochondrial dysfunction, which can be caused by metabolic stressors such as oxidized low-density lipoprotein (oxLDL), sensitizes the endothelium to pathological changes. The transcription factor interferonregulatoryfactor 1 (IRF-1) is a master regulator of inflammation, previously shown to promote oxLDL-induced inflammatory pyroptosis in human aortic endothelial cells (HAEC). However, a presumed role for IRF-1 in regulating the intrinsic apoptotic pathway in response to metabolic stress has not been demonstrated. Here targeted deletion of IRF-1 by siRNA in HAEC aggravated oxLDL-induced, mitochondria-mediatedintrinsicapoptosis, as evidenced by increased Caspase-3 and Caspase-9 activation, and chromosomal DNA breakage. The increased apoptosis was concomitant with accumulation of mitochondrial ROS, decrease in intracellular ATP production and respiratory oxygen consumption, and abnormal mitochondrial structure. RNA profiling of endothelial cells isolated from wild type and Irf1 knockout mice, followed by quantitative PCR, luciferase activity assay and chromatin immunoprecipitation (ChIP), revealed that IRF-1 directly regulated the expression of transmembrane protein 70 (TMEM70), an ancillary factor required for the assembly of ATP synthase and conversion of an electrochemical gradient to ATP synthesis. Mirroring the effect of IRF1 knockdown, depletion of TMEM70 in HAEC resulted in impaired mitochondrial function and enhanced cell apoptosis. In contrast, overexpression of TMEM70 rescued ATP biosynthesis and suppressed apoptosis in oxLDL-treated, IRF-1-deficient HAEC. These results reveal a novel homeostatic role for IRF-1 in the regulation of mitochondrial function and associated stress-induced apoptosis.

Endothelial cell Ass1 inhibits arteriosclerotic calcification in diabetes mellitus

Endothelial cell (EC) dysfunction is an important pathological feature of early calcification in diabetic plaques. Argininosuccinic synthase 1 (Ass1) is important in protecting EC activity. Therefore, this study aimed to explore the effect of endothelial Ass1 on calcification in diabetic plaques and its potential regulatory mechanism. In this study, serum Ass1 levels were measured in 84 patients, and the study showed that the serum Ass1 level in patients with diabetes was significantly decreased compared with the non-diabetic group, and the serum Ass1 level in patients with coronary artery calcification was significantly decreased compared with the non-coronary artery calcification group. The ApoE-/- mouse diabetic plaque calcification model and the mouse aortic endothelial cell (MAEC) calcification model were constructed, and the influence of endothelial cell Ass1 on diabetic plaque calcification was further investigated by adeno-associated virus and plasmid intervention. Molecular biology studies have shown that endothelial Ass1 overexpression can reduce plaque calcification and inhibit MAEC osteogenic differentiation in diabetic mice, and Ass1 has protective effects on EC and blood vessels in mice. 4D-label-free proteomic sequencing, bioinformatics analysis, and IP experiments were performed on ApoE-/- mouse aorta after adeno-associated virus intervention. It was found that the differential protein Ptk2b was closely related to vascular calcification (VC) and interacted with the target protein Ass1. The above studies indicate that endothelial Ass1 affects calcification formation in diabetic plaques, and the mechanism may be related to Ptk2b. Ass1 may be a new target for the treatment of diabetic VC.

Angiotensin II Exposure In Vitro Reduces High Salt-Induced Reactive Oxygen Species Production and Modulates Cell Adhesion Molecules’ Expression in Human Aortic Endothelial Cell Line

Background/Objectives: Increased sodium chloride (NaCl) intake led to leukocyte activation and impaired vasodilatation via increased oxidative stress in human/animal models. Interestingly, subpressor doses of angiotensin II (AngII) restored endothelium-dependent vascular reactivity, which was impaired in a high-salt (HS) diet in animal models. Therefore, the present study aimed to assess the effects of AngII exposure following high salt (HS) loading on endothelial cells’ (ECs’) viability, activation, and reactive oxygen species (ROS) production. Methods: The fifth passage of human aortic endothelial cells (HAECs) was cultured for 24, 48, and 72 h with NaCl, namely, the control (270 mOsmol/kg), HS320 (320 mOsmol/kg), and HS350 (350 mOsmol/kg). AngII was administered at the half-time of the NaCl incubation (10−4–10−7 mol/L). Results: The cell viability was significantly reduced after 24 h in the HS350 group and in all groups after longer incubation. AngII partly preserved the viability in the HAECs with shorter exposure and lower concentrations of NaCl. Intracellular hydrogen peroxide (H2O2) and peroxynitrite (ONOO−) significantly increased in the HS320 group following AngII exposure compared to the control, while it decreased in the HS350 group compared to the HS control. A significant decrease in superoxide anion (O2.−) formation was observed following AngII exposure at 10−5, 10−6, and 10−7 mol/L for both HS groups. There was a significant decrease in intracellular adhesion molecule 1 (ICAM-1) and endoglin expression in both groups following treatment with 10−4 and 10−5 mol/L of AngII. Conclusions: The results demonstrated that AngII significantly reduced ROS production at HS350 concentrations and modulated the viability, proliferation, and activation states in ECs.

Forkhead box P1 transcriptionally activates IGF-1 to lighten ox-LDL-induced endothelial cellular senescence by inactivating NLRP3 inflammasome.

Endothelial cell (EC) senescence is a major contributor in atherosclerosis (AS) development. Herein, the role of forkhead box P transcription factor 1 (FOXP1) and insulin-like growth factor (IGF)-1 in regulating EC senescence during AS progression was investigated. The mRNA and protein expressions were assessed using qRT-PCR and western blot. IL-1β and IL-18 secretion levels were analyzed by ELISA. Cell viability and pyroptosis were determined by MTT assay and flow cytometry, respectively. SA β-Gal staining was used to measure cell senescence. Tube formation assay was adopted to detect the angiogenesis ability. Dual-luciferase reporter and ChIP assays were used to investigate the relationship between FOXP1 and IGF‑1. ox-LDL stimulation significantly reduced FOXP1 and IGF-1 expression levels in human aortic endothelial cells (HAECs). FOXP1 or IGF-1 overexpression both mitigated ox-LDL-induced cellular senescence and NLRP3 activation in HAECs. It was subsequently revealed that FOXB1 transcriptionally activated IGF-1 expression in HAECs by binding to IGF-1 promoter. Rescue experiments demonstrated that IGF-1 silencing abolished the inhibitory impact of FOXP1 overexpression on ox-LDL-induced cellular senescence and NLRP3 activation in HAECs. FOXP1 transcriptionally activated IGF-1 to lighten ox-LDL-induced endothelial cellular senescence by inactivating NLRP3 inflammasome.

Low-magnitude high-frequency vibration ameliorates high glucose-induced endothelial injury by restoring mitochondrial function via AMPK/mTOR pathway

ABSTRACT High glucose-induced dysfunction of endothelial cells is a critical and initiating factor in the genesis of diabetic vascular complications. Low-magnitude high-frequency vibration (LMHFV) is a non-invasive biophysical intervention. It has been reported that it exhibits protective effects on high glucose-induced osteoblast dysfunction, but little was known on diabetic vascular complications. In this work, we aim to clarify the role of LMHFV on high glucose-induced endothelial dysfunction and hypothesized that the protective effects functioned through adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway. We cultured primary murine aortic endothelial cells (MAECs) in normal or HG medium, respectively, before exposing to LMHFV. The tube formation, paracellular permeability assay, and aortic ring sprouting assay showed that the high glucose injured-function of MAECs was improved after LMHFV treatment. The intracellular ROS generation analysis, mitochondrial complex I activities measurement, ATP measurement and mitochondrial membrane potential (MMP), and mitochondrial ROS generation analysis of MAECs indicated that mitochondrial function was restored by LMHFV loading in a high glucose environment. Mechanically, western blot assays showed that AMPK phosphorylation was promoted and mTOR was inhibited in LMHFV-induced endothelial function restoration. After the administration of the AMPK inhibitor, Compound C, these protective effects resulting from LMHFV are reversed. These findings suggest that LMHFV plays a significant role in protecting endothelial cells’ function and mitochondrial function in high glucose-induced injured MAECs via AMPK/mTOR signalling.

The alarmin, interleukin-33, increases vascular tone via extracellular signal regulated kinase-mediated Ca2+ sensitization and endothelial nitric oxide synthase inhibition.

Alarmins are classified by their release from damaged or ruptured cells. Many alarmins have been found to increase vascular tone and oppose endothelium-dependent dilatation (EDD). Interleukin (IL)-33 plays a prominent role in lung injury and can be released during vascular injury and in chronic studies found to be cardioprotective. Our recent work has implicated IL-33 in acute vascular dysfunction following inhalation of engineered nanomaterials (ENM). However, the mechanisms linking IL-33 to vascular tone have not been interrogated. We therefore aimed to determine whether IL-33 directly influenced microvascular tone and endothelial function. Isolated feed arteries and in vivo arterioles from male and female Sprague-Dawley rats were used to determine direct vascular actions of IL-33. Mesenteric feed arteries and arterioles demonstrated reduced intraluminal diameters when treated with increasing concentrations of recombinant IL-33. IL-33 activated extracellular signal regulated kinase (ERK)1/2 of rat aortic smooth muscle cells but not phosphorylation of myosin light chain kinase. This suggested IL-33may sensitize arterioles to Ca2+-mediated responses. Indeed, IL-33 augmented the myogenic- and phenylephrine-induced vasoconstriction. Additionally, incubation of arterioles with 1ng IL-33 attenuated ACh-mediated EDD. Mechanistically, in human aortic endothelial cells, we demonstrate that IL-33-mediated ERK1/2 activation leads to inhibitory phosphorylation of serine 602 on endothelial nitric oxide synthase. Finally, we demonstrate that IL-33-ERK1/2 contributes to vascular tone following two known inducers of IL-33; ENM inhalation and the rupture endothelial cells. The present study provides novel evidence that IL-33 increases vascular tone via canonical ERK1/2 activation in microvascular smooth muscle and endothelium. Altogether, it is suggested IL-33 plays a critical role in microvascular homeostasis following barrier cell injury. KEY POINTS: Interleukin (IL)-33 causes a concentration-dependent reduction in feed artery diameter. IL-33 acts on vascular smooth muscle cells to augment Ca2+-mediated processes. IL-33 causes inhibitory phosphorylation of endothelial nitric oxide synthase and opposes endothelium-dependent dilatation. Engineered nanomaterial-induced lung injury and endothelial cell rupture in part act through IL-33 to mediate increased vascular tone.

Abstract 4132409: Caspase-4/11 promotes a high-fat diet and chronic kidney disease-accelerated vascular inflammation via caspase-4/11-IL-1b two-tier trained immunity

Introduction: Chronic kidney disease (CKD) is a common inflammatory disease affecting >15% of the adult population and 50% of all patients with advanced/end stages (4 to 5) of CKD have cardiovascular disease. Research Questions: How multiple disease risk factors interplay to accelerate vascular inflammation in CKD. Aim: To determine whether hyperlipidemia and CKD have a synergy in accelerating vascular inflammation via trained immunity (TI). Methods: we performed aortic pathological analysis and RNA-sequencing in high-fat diet (HFD)-fed 5/6 nephrectomy CKD (HFD+CKD) mice. Results: 1) HFD+CKD increases aortic cytosolic lipopolysaccharide (LPS) levels, caspase-11 (casp11) activation, and 998 gene expressions of TI pathways in the aorta (first-tier TI mechanism); 2) Casp11 —/— decreases aortic neointima hyperplasia, aortic recruitment of macrophages, and casp11-gasdermin D-mediated cytokine secretion; 3) Casp11 —/— decreases N-terminal gasdermin D (N-GSDMD) membrane expression on aortic endothelial cells and aortic IL-1b levels; 4) LPS transfection into human aortic endothelial cells results in casp4 (human)/casp11 (mouse) activation and increases N-GSDMD membrane expression; 5) IL-1b serves as the second-tier mechanism underlying HFD+CKD-promoted TI. Conclusion: Hyperlipidemia and CKD accelerate vascular inflammation by promoting two-tier trained immunity

Endothelial-to-Mesenchymal Transition Contributes to Accelerated Atherosclerosis in Hutchinson-Gilford Progeria Syndrome.

Atherosclerosis is the main medical problem in Hutchinson-Gilford progeria syndrome, a rare premature aging disorder caused by the mutant lamin-A protein progerin. Recently, we found that limiting progerin expression to vascular smooth muscle cells (VSMCs) is sufficient to hasten atherosclerosis and death in Apoe-deficient mice. However, the impact of progerin-driven VSMC defects on endothelial cells (ECs) remained unclear. Apoe- or Ldlr-deficient C57BL/6J mice with ubiquitous, VSMC-, EC- or myeloid-specific progerin expression fed a normal or high-fat diet were used to study endothelial phenotype during Hutchinson-Gilford progeria syndrome-associated atherosclerosis. Endothelial permeability to low-density lipoproteins was assessed by intravenous injection of fluorescently labeled human low-density lipoprotein and confocal microscopy analysis of the aorta. Leukocyte recruitment to the aortic wall was evaluated by en face immunofluorescence. Endothelial-to-mesenchymal transition (EndMT) was assessed by quantitative polymerase chain reaction and RNA sequencing in the aortic intima and by immunofluorescence in aortic root sections. TGFβ (transforming growth factor β) signaling was analyzed by multiplex immunoassay in serum, by Western blot in the aorta, and by immunofluorescence in aortic root sections. The therapeutic benefit of TGFβ1/SMAD3 pathway inhibition was evaluated in mice by intraperitoneal injection of SIS3 (specific inhibitor of SMAD3), and vascular phenotype was assessed by Oil Red O staining, histology, and immunofluorescence in the aorta and the aortic root. Both ubiquitous and VSMC-specific progerin expression in Apoe-null mice provoked alterations in aortic ECs, including increased permeability to low-density lipoprotein and leukocyte recruitment. Atherosclerotic lesions in these progeroid mouse models, but not in EC- and myeloid-specific progeria models, contained abundant cells combining endothelial and mesenchymal features, indicating extensive EndMT triggered by dysfunctional VSMCs. Accordingly, the intima of ubiquitous and VSMC-specific progeroid models at the onset of atherosclerosis presented increased expression of EndMT-linked genes, especially those specific to fibroblasts and extracellular matrix. Aorta in both models showed activation of the TGFβ1/SMAD3 pathway, a major trigger of EndMT, and treatment of VSMC-specific progeroid mice with SIS3 alleviated the aortic phenotype. Progerin-induced VSMC alterations promote EC dysfunction and EndMT through TGFβ1/SMAD3, identifying this process as a candidate target for Hutchinson-Gilford progeria syndrome treatment. These findings also provide insight into the complex role of EndMT during atherogenesis.

Abstract 4138754: Analysis of Polarization Changes in Ascending Aortic Endothelial Cells Induced by Aortic Valve Regurgitation

Background: Fragility of the ascending aortic wall has been reported in patients with aortic regurgitation (AR), thought to be affected by turbulence in the ascending aorta. However, the mechanism behind this effect is unclear. We hypothesized that turbulence in the ascending aorta of AR patients causes changes in the polarization of endothelial cells. This study aimed to clarify that the polarization of endothelial cells in the ascending aortic wall is altered in AR patients. Methods: Twenty patients who underwent ascending aortic replacement at our institution from October 2022 to July 2023 were included: ten with thoracic aortic aneurysms (TAA) and ten with TAA and AR. The polarization of endothelial cells in the greater curvature of the ascending aortic wall collected during surgery was evaluated by measuring the ratio of the long axis to the short axis, the angle between the long axis and the blood flow axis, and the alignment of the Golgi apparatus and nucleus parallel to the blood flow. Results: There were no significant differences in patient background between the AR and non-AR groups. Additionally, there was no significant difference in the diameter of the ascending aorta between the two groups (AR vs. non-AR, 47.7±3.8 mm vs. 44.5±2.2 mm, p=0.479). The long axis to short axis ratio (aspect ratio) of endothelial cells in the ascending aorta was significantly smaller in the AR group than in the non-AR group. The angle (θ) between the long axis of the endothelial cells and the blood flow axis was significantly smaller in the AR group than in the non-AR group. The ratio of Golgi apparatus and nucleus alignment parallel to the blood flow was significantly lower in the AR group than in the non-AR group. Degeneration of the aortic tunica media was also observed in the AR group compared to the non-AR group. Conclusion: The results of this study suggest that the presence of AR alters the polarization of endothelial cells in the ascending aortic wall.

Abstract 4113617: Single-cell Analysis Reveals Endothelial Cell CD45 Deficiency Prevents Endothelial-to-Mesenchymal Transition (EndMT) in Atherosclerosis

Introduction: Protein-tyrosine-phosphatase CD45 is exclusively expressed in all nucleated cells of the hematopoietic system but is rarely expressed in endothelial cells (ECs). However, a recent study indicated that activation of the endogenous CD45 promoter in human endothelial colony forming cells induced expression of EndMT marker genes. Also, the CD45 phosphatase inhibitor blocked EndMT activities in TGFβ1-treated ovine mitral valve endothelial cells. EndMT contributes to atherosclerotic pathobiology and is associated with more complex plaques. We identified CD45-positive ECs undergoing EndMT in atherosclerotic ApoE-deficient (ApoE -/- ) mice. Here, we aim to investigate whether endothelial CD45-specific deletion can prevent EndMT in a mouse model of atherosclerosis. Methods and Results: We generated a tamoxifen-inducible EC-specific CD45-deficient mouse strain (EC-iCD45KO) on an ApoE -/- background (C57BL/6) and fed these mice a Western diet for 16 weeks. We isolated and enriched mouse aortic endothelial cells with CD31 beads to perform single-cell RNA-seq. Cells populated 15 major clusters after integrating the single-cell transcriptomic profiles. In the EC-iCD45KO group, the population of endothelial, resident macrophage, and mesenchymal-endothelial transition cells increased while vascular smooth muscle, EndMT, and fibroblast cells decreased. In EndMT cells, EC markers (Cdh5, Cldn5, Pecam1) increased, but SMC markers (Acta2) and EndMT markers (Col1a2 and Col3a1）decreased. In addition, we characterized EndMT cells into two sub-clusters: 1 and 2. EC-specific CD45 deletions reduced the cell numbers in the EndMT2 sub-cluster in atherosclerotic mice but had less impact on the EndMT1 sub-cluster. FGFR pathways were potentiated while TGFβ1 and Tgfbr2 decreased in EndMT1 sub-cluster， and the genes controlling endothelial cell development were upregulated but the genes controlling actin cytoskeleton organization were downregulated in both EndMT1 and 2 sub-clusters. Conclusion: Our single-cell analysis indicates that the loss of endothelial CD45 protects against EndMT-driven atherosclerosis, inhibiting TGFβ and EndoMT marker expression while stimulating FGFR pathways. Consistently, EC-iCD45KO/ApoE -/- mice showed reduced plaque macrophages, expression of cell adhesion molecules, foam cell formation, and lesion development when compared to ApoE -/- controls. Thus, targeting endothelial CD45 may be a novel therapeutic strategy for EndMT and atherosclerosis.

Abstract 4114308: Defective in LYPLA1-Mediated Lysophosphatidylcholine Metabolism Contributes to Diabetes-Induced Atherosclerosis and Subsequent Myocardial Dysfunction

Background and Objective: Diabetes mellitus (DM) is a chronic metabolic condition that can cause serious damage to blood vessels and the heart. While current metabolomics research mainly focused on metabolic profiles during disease onset or at advanced stages, there remains a gap in understanding the molecular mechanisms of metabolites in the progression of diabetic cardiovascular disease. This study aims to explore effective strategies for preventing cardiovascular complications in diabetics by excavating metabolic pathways and mechanisms. Methods: Peripheral blood samples were obtained from 21 healthy individuals, 20 patients diagnosed with DM, 20 patients with coronary heart disease (CHD), and 25 patients with both DM and CHD (DC). Cardiac function, biochemical parameters and serum metabolome were detected. A specialized methodology with rigorous screening criteria was employed to identify differential metabolites associated with diabetes-induced CHD and cardiomyopathy. Mice were injected with LPC16:0 to assess cardiovascular function. Models of diabetes and diabetic atherosclerosis were induced by STZ injection and high-fat diet feeding in WT and ApoE -/- mice. Cardiac function and differential metabolites in aortic and cardiac tissues were assessed. The effect and molecular mechanism of LYPLA1 on vascular function, mitochondrial function, and metabolites-related enzymes were examined in human aortic endothelial cells (HAECs) and AC16 cardiomyocytes. Results: Cardiac function was markedly declined in DM and DC patients, as well as in mice with diabetes and diabetic atherosclerosis. However, CHD patients and atherosclerosis alone did not exhibit evident cardiac dysfunction. Key metabolites associated with diabetic cardiomyopathy and diabetes-induced CHD were identified as LPE18:1 and LPC16:0, respectively. Intraperitoneal administration of LPC16:0 in mice led to decreased LYPLA1, severe myocardial anomalies, and the appearance of plaques in the aortic arch. Either LYPLA1 knockdown or the treatment with high glucose and palmitic acid in HAECs resulted in impaired mitochondrial function, reduced intracellular NO and eNOS activity, which were mitigated by LYPLA1 overexpression. Conclusion: The metabolite LPC16:0 and the regulatory enzyme LYPLA1 are pivotal in driving the advancement of cardiovascular complications triggered by diabetes. Targeting LYPLA1 could represent a promising strategy for preventing diabetes-induced CHD and subsequent cardiomyopathy.

Abstract 4137257: Hepatocyte growth factor -mediated Angiogenesis supersession in Hyperhomocysteinemia

Background: Homocysteine (Hcy) is a well-established cardiovascular risk factor. Elevated homocysteine, or hyperhomocysteinemia (HHcy), inhibit the growth of endothelial cells and stimulate vascular smooth muscle cell proliferation. However, the mechanisms of HHcy disrupts angiogenesis remain unclear. Here we examine the molecular pathways involved in HHcy-impaired angiogenesis. Method: We generated Tg-hCBS+ Cbs-/- mice by crossing Cbs knockout mice and Tg-hCBS mice where human CBS cDNA was regulated by a zinc-inducible metallothionein promoter. The model exhibited severe HHcy (＞115 μmol/L). We conducted both in vivo and in vitro experiments, including vasculogenesis assays of retinal and heart tissues, aortic ring assay, and tube formation. Retinas were stained with Isolectin B4 and imaged using a confocal microscope. The Human Angiogenesis RT 2 Profiler™ PCR Array was used to profile 84 key angiogenesis-related genes. Homocysteine metabolites in Cbs mice were measured by HPLC. ChIP-seq data were analyzed using Chip Atlas. Additionally, 91 patients went through coronary angiography were enrolled from the Second Affiliated Hospital of Nanchang University. Participants with CTFC, greater than 27 frames per second were identified as having slow coronary arteries flow (SCF). Results: HHcy caused SCF in patients and impaired vasculogenesis in the retinas of newborn and 12-week-old Tg-hCBS Cbs-/- mice. Capillary density in the hearts of adult Tg-hCBS Cbs-/- mice was reduced. HHcy suppressed tube formation and aortic ring microvessel growth in a concentration-dependent manner. The PCR array revealed significant gene expression changes in Hcy treated human aortic endothelial cells. Notably, genes encoding hepatocyte growth factor (HGF), collagen type IV alpha 3, epiregulin, interferons, and leukocyte cell-derived chemotaxin 1 were downregulated by at least four-fold. In an acute myocardial infarction model, HGF expression was further reduced, and HGF treatment rescued Hcy-inhibited tube formation and microvessel growth. Hcy and S-adenosylhomocysteine levels were negatively correlated with plasma HGF levels. ChIP-seq data identified homocysteine-responsive hypomethylation in ETF, TFII, FOXP3, RXRa, and c-Jun Hcy-hypomethylation Box (-2701/0). Conclusion: HHcy impair angiogenesis via HGF inhibition, which has a rescue effect. Hypomethylation caused by Hcy affects the methylation status of specific CpG sites within the Hcy-hypomethylation box of the HGF gene.

Abstract 4122717: An Epigenetic Drug, GSK126 Mitigates Endothelial to Mesenchymal Transition Attenuating Atherosclerosis in Diabetes

Background: Endothelial to mesenchymal transition (EndMT) involves transformation of an endothelial to mesenchymal like cellular state. Recent studies implicate EndMT in atherosclerosis development. Diabetes is associated with both EndMT as well as accelerated atherosclerosis. Experimental evidence supports the use of epigenetic drugs that act on relevant epigenetic mechanisms to attenuate atherosclerosis. Recently, inhibition of a histone methyltransferase Enhancer of zest homolog 2 (EZH2) with GSK-126 attenuated atherosclerosis development. However, the role of EZH2 in induction of EndMT in diabetes induced atherosclerosis is not known. Methods: An in-vitro model of EndMT was generated using high glucose (HG) and TNF-α in human aortic endothelial cells (HAECs). EZH2 methyltransferase activity was inhibited using EZH2 specific inhibitor GSK-126. RNA sequencing was performed in this setting. EZH2 genetic knockdown (shRNA) in HAECs was also performed to validate role of EZH2 in EndMT. In addition, EZH2 mediated H3K27me3 and EndMT was assessed in atheroprone diabetic mouse model. Results: In HAECs, morphological changes as well as gene and protein expression confirmed TNF-α+HG induced EndMT, which was blunted by GSK-126. Elevated EZH2 mediated H3K27me3 activity by the TNF-α + HG stimulation was blunted with GSK-126 treatment. Furthermore, RNA sequencing identified several enriched pathways including AGE-RAGE signaling pathway in diabetic complications, focal adhesion, and leukocyte trans-endothelial migration directly relevant to EndMT and commonly deregulated in diabetic complications, which were rescued by EZH2 inhibition. Transcriptomic analysis showed that 242 genes including MMP2, NOS3 linked to EndMT were dysregulated. Interestingly, expression of 76 dysregulated genes in EndMT were rescued by GSK-126. EZH2 knockdown studies in HAECs also validated the role of EZH2 in EndMT. Furthermore, immunofluorescence staining identified elevated levels of H3K27me3 in the aortic endothelial layer of diabetic Apoe -/- mice. Co-localization of EndMT markers was observed in the endothelial layer of aortic sinus of diabetic Apoe -/- mice which was blunted with GSK-126 treatment. Conclusion: The study identified EZH2 inhibition as a novel therapeutic target in diabetes induced EndMT in atherosclerosis. These findings highlighted ongoing efforts to develop targeted therapies for diabetic patients who are at risk to develop cardiovascular disease.

VE-cadherin shedding in vitro and in patients with aortic aneurysm and dissection

VE-cadherin (VEC) is a major endothelial adhesion protein, which controls vascular homeostasis. During vascular diseases, VEC can be shed from the endothelial surface by proteases like ADAM10/17, which cleave the extracellular domain of VEC in response to inflammatory cytokines like TNF-α. The resulting, soluble fragments (sVEC) are discussed as a potential marker for endothelial barrier breakdown. However, its pathologic role or its potential as a specific biomarker for aortic diseases is yet unknown. Here we investigated the specificity and linkage of sVEC production with ADAM10/17 and TNF-α, both in vitro and in patients with aortic aneurysms and dissections, comparing the findings with those from patients with carotid stenosis and varicosis. Thereby, the baseline levels of sVEC, TNF-α, ADAM10 and Albumin was measured in clinical plasma samples and cell culture supernatants of human aortic endothelial cells (HAOEC) treated with TNF-α or ADAM10/17 inhibitors. The integrity of HAOEC monolayers was tested by permeability assays using Alexa488-conjugated dextran (10 kDa). Peripheral EDTA plasma samples taken preoperatively from patients ≥ 18 years of age that were diagnosed for aortic dissection (n = 29), aortic aneurysm (n = 76), carotid stenosis (n = 29) and varicose veins (n = 24) were included. In vitro shedding of VEC was induced by TNF-α and depends on ADAM10/17, which led to altered endothelial permeability. Absolute plasma sVEC levels in patients with aortic dissection (3016 ± 1008 ng/mL) and aneurysm (3288 ± 1376 ng/mL) were not statistically significantly different from patients with carotid stenosis (3013 ± 687.6 ng/mL) and varicose veins (3313 ± 1337 ng/mL). Plasma sVEC levels correlated positively with plasma TNF-α (r = 0.5586, p < 0.0001) and ADAM10 (r = 0.7003, p < 0.0001) levels with the highest degree of correlation between ADAM10 and sVEC for chronic aortic dissection (r = 0.7890, p = 0.0013), reflecting TNF-α and ADAM10 dependency of VEC shedding. In summary, VEC shedding and (plasma) sVEC levels are influenced by TNF-α and ADAM10/17 and could play a relevant role in the specific pathophysiological context of aortic diseases.

Fluorescent gold nanoclusters possess multiple actions against atherosclerosis

Atherosclerosis caused major morbidity and mortality worldwide. Molecules possessing lipid-lowering and/or anti-inflammatory properties are potential druggable targets against atherosclerosis. We examined the anti-atherosclerotic effects of fluorescent gold nanoclusters (FANC), which were dihydrolipoic acid (DHLA)-capped 2-nm gold nanoparticles. We evaluated the 8-week effects of FANC in Western-type diet-fed ApoE-deficient mice by either continuous intraperitoneal delivery (20 μM, 50 μl weekly) or via drinking water (300 nM). FANC reduced aortic atheroma burden, serum total cholesterol, and oxidative stress markers malondialdehyde and 4-hydroxynonenal levels. FANC attenuated hepatic lipid deposit, with changed expression of lipid homeostasis-related genes HMGCR, SREBP, PCSK9, and LDLR in a pattern similar to mice treated with ezetimibe. FANC also inhibited intestinal cholesterol absorption, resembling the action of ezetimibe. The lipid-lowering and anti-atherosclerotic effects of FANC reappeared in Western-type diet-fed LDLr-deficient mice. FANC bound insulin receptor β (IRβ) via DHLA, leading to AKT activation. However, unlike insulin, which also bound IRβ to activate AKT to induce HO-1, activation of AKT by FANC was independent of HO-1 expression in human aortic endothelial cells (HAECs). Alternatively, FANC up-regulated NRF2, interfered the binding of KEAP1 to NRF2, and promoted KEAP1 degradation to free NRF2 for nuclear entry to induce HO-1 that suppressed the expression of ICAM-1 and VCAM-1. Consistently, FANC suppressed ox-LDL-induced enhanced attachment of THP-derived macrophages onto HAECs. In macrophages, FANC up-regulated ABCA1, and reversed ox-LDL-induced suppression of cholesterol efflux. FANC effected in vitro at nano moles. In conclusion, our findings showed novel actions and multiple mechanisms of FANC worked coherently against atherosclerosis.

Panax notoginseng saponins improves lipid metabolism and prevents atherosclerosis in mice with steroid-resistant lupus nephritis via the SIRT1/PPARγ signaling pathway

Steroids serve as the primary medication for treating lupus nephritis (LN), however, steroid-resistance (SR) occurs sporadically in clinical practice, significantly affecting the therapeutic effect and long-term prognosis of patients. Our previous study found that panax notoginseng saponins (PNS) could partially reverse SR in LN. To further explore the role of PNS in reversing SR and reducing cardiovascular complications in LN, we conducted this study. Lupus mice were induced into SR while simultaneously receiving PNS. SIRT1-siRNA, SIRT1-siRNA NC, normal and lupus mice were used as control groups. Urine protein levels were measured at week 0, 4 and 8. Lipid metabolism-related biomarkers and renal function were assessed. The apoptosis rate of abdominal aortic endothelial cells was detected using flow-cytometry. The expression levels of PPARγ and SIRT1 were measured using RT-PCR and Western Blotting. Immunohistochemistry was performed to examine ACAT1 and VCAM-1 expressions. The results showed that compared to the SR lupus mice, the lupus mice treated with low/high dose PNS presented lower levels of urinary protein, serum creatinine, and blood lipids, a lower apoptosis rate of abdominal aortic endothelial cells, and decreased levels of ACAT1 and VCAM-1 PI in liver tissue, while the high-dose PNS exhibited more evidently. The PPARγ expression in SIRT1-siRNA group, as well as in low-dose and high-dose PNS groups was higher than that in the lupus and SR lupus group. In contrast, the expression of SIRT1 showed the opposite trend. Therefore, we conclude that PNS has the efficacy of reversing SR and ameliorating dyslipidemia in LN by modulating the SIRT1/PPARγ signaling pathway.

Targeted NAD+ repletion via biomimetic nanoparticle enables simultaneous management of intimal hyperplasia and accelerated re-endothelialization: A proof-of-concept study toward next-generation of endothelium-protective, anti-restenotic therapy

Endovascular interventions often fail due to restenosis, primarily caused by smooth muscle cell (SMC) proliferation, leading to intimal hyperplasia (IH). Current strategies to prevent restenosis are far from perfect and impose significant collateral damage on the fragile endothelial cell (EC), causing profound thrombotic risks. Nicotinamide adenine dinucleotide (NAD+) is a co-enzyme and signaling substrate implicated in redox and metabolic homeostasis, with a pleiotropic role in protecting against cardiovascular diseases. However, a functional link between NAD+ repletion and the delicate duo of IH and EC regeneration has yet to be established. NAD+ repletion has been historically challenging due to its poor cellular uptake and low bioavailability. We have recently invented the first nanocarrier that enables direct intracellular delivery of NAD+ in vivo. Combining the merits of this prototypic NAD+-loaded calcium phosphate (CaP) nanoparticle (NP) and biomimetic surface functionalization, we created a biomimetic P-NAD+-NP with platelet membrane coating, which enabled an injectable modality that targets IH with excellent biocompatibility. Using human cell primary culture, we demonstrated the benefits of NP-assisted NAD+ repletion in selectively inhibiting the excessive proliferation of aortic SMC, while differentially protecting aortic EC from apoptosis. Moreover, in a rat balloon angioplasty model, a single-dose treatment with intravenously injected P-NAD+-NP immediately post angioplasty not only mitigated IH, but also accelerated the regeneration of EC (re-endothelialization) in vivo in comparison to control groups (i.e., saline, free NAD+ solution, empty CaP-NP). Collectively, our current study provides proof-of-concept evidence supporting the role of targeted NAD+ repletion nanotherapy in managing restenosis and improving reendothelialization.

Dapagliflozin mitigates cellular stress and inflammation through PI3K/AKT pathway modulation in cardiomyocytes, aortic endothelial cells, and stem cell-derived β cells

Dapagliflozin (DAPA), a sodium-glucose cotransporter 2 (SGLT2) inhibitor, is well-recognized for its therapeutic benefits in type 2 diabetes (T2D) and cardiovascular diseases. In this comprehensive in vitro study, we investigated DAPA’s effects on cardiomyocytes, aortic endothelial cells (AECs), and stem cell-derived beta cells (SC-β), focusing on its impact on hypertrophy, inflammation, and cellular stress. Our results demonstrate that DAPA effectively attenuates isoproterenol (ISO)-induced hypertrophy in cardiomyocytes, reducing cell size and improving cellular structure. Mechanistically, DAPA mitigates reactive oxygen species (ROS) production and inflammation by activating the AKT pathway, which influences downstream markers of fibrosis, hypertrophy, and inflammation. Additionally, DAPA’s modulation of SGLT2, the Na+/H + exchanger 1 (NHE1), and glucose transporter (GLUT 1) type 1 highlights its critical role in maintaining cellular ion balance and glucose metabolism, providing insights into its cardioprotective mechanisms. In aortic endothelial cells (AECs), DAPA exhibited notable anti-inflammatory properties by restoring AKT and phosphoinositide 3-kinase (PI3K) expression, enhancing mitogen-activated protein kinase (MAPK) activation, and downregulating inflammatory cytokines at both the gene and protein levels. Furthermore, DAPA alleviated tumor necrosis factor (TNFα)-induced inflammation and stress responses while enhancing endothelial nitric oxide synthase (eNOS) expression, suggesting its potential to preserve vascular function and improve endothelial health. Investigating SC-β cells, we found that DAPA enhances insulin functionality without altering cell identity, indicating potential benefits for diabetes management. DAPA also upregulated MAFA, PI3K, and NRF2 expression, positively influencing β-cell function and stress response. Additionally, it attenuated NLRP3 activation in inflammation and reduced NHE1 and glucose-regulated protein GRP78 expression, offering novel insights into its anti-inflammatory and stress-modulating effects. Overall, our findings elucidate the multifaceted therapeutic potential of DAPA across various cellular models, emphasizing its role in mitigating hypertrophy, inflammation, and cellular stress through the activation of the AKT pathway and other signaling cascades. These mechanisms may not only contribute to enhanced cardiac and endothelial function but also underscore DAPA’s potential to address metabolic dysregulation in T2D.Graphical abstract

Genetically Engineered Clostridium Prevents Perivascular Adipose Tissue and Endothelial Senescence and Dysfunction in Aging

Abstract Introduction (Peri)vascular senescence is a bona fide risk for several aging-associated diseases that threatens healthspan. Gut microbiome may be one of triggers that promotes vascular diseases as host ages. However, the interplay between vascular senescence and gut microbiome is largely unknown. Our recent studies revealed an increase in gut-derived phenylacetic acid (PAA) in the aging population (TwinsUK Aging Cohort, n=7,303) and aged mice. Our preliminary shotgun metagenomics also showed that ppfor-harboring Clostridium sp. ASF356 age-dependently generates PAA, which induces perivascular adipose tissue (PVAT) and endothelial cell (EC) senescence and dysfunction in old mice. Yet, it remains unclear whether and how genetic engineering of Clostridium sp. ASF356 (by depleting ppfor gene) can prevent aortic PVAT-EC senescence and restore vascular function in aging. Methods For bacterial genetic engineering, we depleted ppfor gene in Clostridium ASF356 by ClosTron technique and further mono-colonized aged mice (24-months old) and germ-free mice, as control, to reduce plasma PAA and thereby prevent aortic PVAT-EC senescence and improve endothelial dysfunction. Results As a proof of the concept, our studies exhibited that mono-colonization of germ-free mice with wild-type Clostridium sp. ASF356 markedly elevates plasma PAA levels. It was accompanied by hallmarks of aortic PVAT-EC senescence, including increased DNA damage (↑ γ-H2A.X phosphorylation), heightened SASP (↑ IL-6 and VCAM1), and proliferative arrest (↑ p16INK4a and p21WAF1/Cip1). Additionally, our findings revealed upreglation of Notch1 in PVAT, contributing to reduced energy supply (↓ UCP1) and augmented senescence-messaging secretome (↑ IL-6) towards ECs. Our further studies revealed that mono-colonization of aged mice (pre-treated with antibiotics) with Δppfor Clostridium ASF356 mutants intriguingly resulted in decreased plasma PAA levels. This intervention led to the rescues of cellular senescence in both aortic PVAT and ECs, consequently improving vascular function. Specifically, mice subjected to this treatment exhibited a significant reduction in SA-β-galactosidase+ cells, as well as decreased levels of γ-H2A.X phosphorylation, p16INK4a, p21WAF1/Cip1, and IL-6 in their aortic PVAT and ECs compared to wild-type aged mice. Conclusions The current study suggests that genetically engineered Δppfor Clostridium ASF356 mutants reverse cellular senescence and restore function in aortic PVAT and endothelial cells, highlighting the potential for targeted gut microbiome manipulation as an innovative senotherapy to combat vascular aging.