Mouse Aorta Research Articles

Evidence for the involvement of TRPV2 channels in the modulation of vascular tone in the mouse aorta

AimsTransient receptor potential vanilloid 2 (TRPV2) channels are expressed in both smooth muscle and endothelial cells and participate in vascular mechanotransduction and sensing of high temperatures and lipids. Nevertheless, the impact of TRPV2 channel activation by agonists on the coordinated and cell-type specific modulation of vasoreactivity is unknown. Main methodsAorta from 2- to 4-months-old male Oncins France 1 mice was dissected and mounted in tissue baths for isometric tension measurements. TRPV2 channel expression was assessed by immunofluorescence and western blot in mice aortas and in cultured A7r5 rat aortic smooth muscle cells. Key findingsTRPV2 channels were expressed in all three mouse aorta layers. Activation of TRPV2 channels with probenecid evoked endothelium-dependent relaxations through a mechanism that involved activation of smooth muscle Kir and Kv channels. In addition, TRPV2 channel inhibition with tranilast increased endothelium-independent relaxations to probenecid and this effect was abrogated by the KATP channel blocker glibenclamide, revealing that smooth muscle TRPV2 channels induce negative feedback on probenecid relaxations mediated via KATP channel inhibition. Exposure to the NO donor sodium nitroprusside increased TRPV2 channel translocation to the plasma membrane in cultured smooth muscle cells and enhanced negative feedback on probenecid relaxations. SignificanceIn conclusion, we present the first evidence that TRPV2 channels may modulate vascular tone through a balance of opposed inputs from the endothelium and the smooth muscle leading to net vasodilation. The fact that TRPV2 channel-induced activity can be amplified by NO emphasizes the pathophysiological relevance of these findings.

Heat stress suppresses MnSOD expression via p53-Sp1 interaction and induces oxidative stress damage in endothelial cells: Protective effects of MitoQ10 and Pifithrin-α

AimTo investigate the mechanism of p53-mediated suppression of heat stress-induced oxidative stress damage by manganese superoxide dismutase (MnSOD) in endothelial cells (ECs). MethodsPrimary ECs isolated from mouse aortas were used to examine the effects of heat stress on vascular ECs viability and apoptosis. We measured MnSOD expression, reactive oxygen species (ROS) production, p53 expression, viability, and apoptosis of heat stress-induced ECs. We also tested the protective effects of MitoQ10, a mitochondrial-targeted antioxidant, and Pifithrin-α, a p53 inhibitor, in ECs from a mouse model of heat stroke. ResultsHeat stress increased cellular apoptosis, ROS production, and p53 expression, while reducing cellular viability and MnSOD expression in ECs. We also showed that the suppression of MnSOD expression by heat stress in ECs was mediated by interactions between p53 and Sp1. Furthermore, MitoQ10 and Pifithrin-α alleviated heat stress-induced oxidative stress and apoptosis in ECs. ConclusionOur results revealed that p53-mediated MnSOD downregulation is a key mechanism for heat stress-induced oxidative stress damage in ECs and indicated that MitoQ10 and Pifithrin-α could be potential therapeutic agents for heat stroke.

Aldose Reductase (AR) Mediates and Perivascular Adipose Tissue (PVAT) Modulates Endothelial Dysfunction of Short-Term High-Fat Diet Feeding in Mice.

Increased adiposity of both visceral and perivascular adipose tissue (PVAT) depots is associated with an increased risk of diabetes and cardiovascular disease (CVD). Under healthy conditions, PVAT modulates vascular tone via the release of PVAT-derived relaxing factors, including adiponectin and leptin. However, when PVAT expands with high-fat diet (HFD) feeding, it appears to contribute to the development of endothelial dysfunction (ED). Yet, the mechanisms by which PVAT alters vascular health are unclear. Aldose reductase (AR) catalyzes glucose reduction in the first step of the polyol pathway and has been long implicated in diabetic complications including neuropathy, retinopathy, nephropathy, and vascular diseases. To better understand the roles of both PVAT and AR in HFD-induced ED, we studied structural and functional changes in aortic PVAT induced by short-term HFD (60% kcal fat) feeding in wild type (WT) and aldose reductase-null (AR-null) mice. Although 4 weeks of HFD feeding significantly increased body fat and PVAT mass in both WT and AR-null mice, HFD feeding induced ED in the aortas of WT mice but not of AR-null mice. Moreover, HFD feeding augmented endothelial-dependent relaxation in aortas with intact PVAT only in WT and not in AR-null mice. These data indicate that AR mediates ED associated with short-term HFD feeding and that ED appears to provoke 'compensatory changes' in PVAT induced by HFD. As these data support that the ED of HFD feeding is AR-dependent, vascular-localized AR remains a potential target of temporally selective intervention.

Oral Administration of Rhamnan Sulfate from Monostroma nitidum Suppresses Atherosclerosis in ApoE-Deficient Mice Fed a High-Fat Diet.

Oral administration of rhamnan sulfate (RS), derived from the seaweed Monostroma nitidum, markedly suppresses inflammatory damage in the vascular endothelium and organs of lipopolysaccharide-treated mice. This study aimed to analyze whether orally administered RS inhibits the development of atherosclerosis, a chronic inflammation of the arteries. ApoE-deficient female mice were fed a normal or high-fat diet (HFD) with or without RS for 12 weeks. Immunohistochemical and mRNA analyses of atherosclerosis-related genes were performed. The effect of RS on the migration of RAW264.7 cells was also examined in vitro. RS administration suppressed the increase in blood total cholesterol and triglyceride levels. In the aorta of HFD-fed mice, RS reduced vascular smooth muscle cell proliferation, macrophage accumulation, and elevation of VCAM-1 and inhibited the reduction of Robo4. Increased mRNA levels of Vcam1, Mmp9, and Srebp1 in atherosclerotic areas of HFD-fed mice were also suppressed with RS. Moreover, RS directly inhibited the migration of RAW264.7 cells in vitro. Thus, in HFD-fed ApoE-deficient mice, oral administration of RS ameliorated abnormal lipid metabolism and reduced vascular endothelial inflammation and hyperpermeability, macrophage infiltration and accumulation, and smooth muscle cell proliferation in the arteries leading to atherosclerosis. These results suggest that RS is an effective functional food for the prevention of atherosclerosis.

Role of CB1 Cannabinoid Receptors in Vascular Responses and Vascular Remodeling of the Aorta in Female Mice.

Both the endocannabinoid system (ECS) and estrogens have significant roles in cardiovascular control processes. Cannabinoid type 1 receptors (CB1Rs) mediate acute vasodilator and hypotensive effects, although their role in cardiovascular pathological conditions is still controversial. Estrogens exert cardiovascular protection in females. We aimed to study the impact of ECS on vascular functions. Experiments were performed on CB1R knockout (CB1R KO) and wild-type (WT) female mice. Plasma estrogen metabolite levels were determined. Abdominal aortas were isolated for myography and histology. Vascular effects of phenylephrine (Phe), angiotensin II, acetylcholine (Ach) and estradiol (E2) were obtained and repeated with inhibitors of nitric oxide synthase (NOS, Nω-nitro-L-arginine) and of cyclooxygenase (COX, indomethacin). Histological stainings (hematoxylin-eosin, resorcin-fuchsin) and immunostainings for endothelial NOS (eNOS), COX-2, estrogen receptors (ER-α, ER-β) were performed. Conjugated E2 levels were higher in CB1R KO compared to WT mice. Vasorelaxation responses to Ach and E2 were increased in CB1R KO mice, attenuated by NOS-inhibition. COX-inhibition decreased Phe-contractions, while it increased Ach-relaxation in the WT group but not in the CB1R KO. Effects of indomethacin on E2-relaxation in CB1R KO became opposite to that observed in WT. Histology revealed lower intima/media thickness and COX-2 density, higher eNOS and lower ER-β density in CB1R KO than in WT mice. CB1R KO female mice are characterized by increased vasorelaxation associated with increased utilization of endothelial NO and a decreased impact of constrictor prostanoids. Our results indicate that the absence or inhibition of CB1Rs may have beneficial vascular effects.

Deletion of vascular thromboxane A2 receptors and its impact on angiotensin II-induced hypertension and atherosclerotic lesion formation in the aorta of Ldlr-deficient mice

The thromboxane A2 receptor (TP) has been shown to play a role in angiotensin II (Ang II)-mediated hypertension and pathological vascular remodeling. To assess the impact of vascular TP on Ang II-induced hypertension, atherogenesis, and pathological aortic alterations, i.e. aneurysms, we analysed Western-type diet-fed and Ang II-infused TPVSMC KO/Ldlr KO, TPEC KO/Ldlr KO mice and their respective wild-type littermates (TPWT/Ldlr KO). These analyses showed that neither EC- nor VSMC-specific deletion of the TP significantly affected basal or Ang II-induced blood pressure or aortic atherosclerotic lesion area. In contrast, VSMC-specific TP deletion abolished and EC-specific TP deletion surprisingly reduced the ex vivo reactivity of aortic rings to the TP agonist U-46619, whereas VSMC-specific TP knockout also diminished the ex vivo response of aortic rings to Ang II. Furthermore, despite similar systemic blood pressure, there was a trend towards less atherogenesis in the aortic arch and a trend towards fewer pathological aortic alterations in Ang II-treated female TPVSMC KO/Ldlr KO mice. Survival was impaired in male mice after Ang II infusion and tended to be higher in TPVSMC KO/Ldlr KO mice than in TPWT/Ldlr KO littermates. Thus, our data may suggest a deleterious role of the TP expressed in VSMC in the pathogenesis of Ang II-induced aortic atherosclerosis in female mice, and a surprising role of the endothelial TP in TP-mediated aortic contraction. However, future studies are needed to substantiate and further elucidate the role of the vascular TP in the pathogenesis of Ang II-induced hypertension, aortic atherosclerosis and aneurysm formation.

Protective effect of microbiota-derived short chain fatty acids on vascular dysfunction in mice with systemic lupus erythematosus induced by toll like receptor 7 activation

Our objective was to investigate whether short-chain fatty acids (SCFAs), specifically acetate and butyrate, could prevent vascular dysfunction and elevated blood pressure (BP) in mice with systemic lupus erythematosus (SLE) induced by TLR7 activation using imiquimod (IMQ). Treatment with both SCFAs and dietary fibers rich in resistant starch (RS) or inulin-type fructans (ITF) effectively prevented the development of hypertension and cardiac hypertrophy. Additionally, these treatments improved aortic relaxation induced by acetylcholine and mitigated vascular oxidative stress. Acetate and butyrate treatments also contributed to the maintenance of colonic integrity, reduced endotoxemia, and decreased the proportion of helper T (Th)17 cells in mesenteric lymph nodes (MLNs), blood, and aorta in TLR7-induced SLE mice. The observed changes in MLNs were correlated with increased levels of GPR43 mRNA in mice treated with acetate and increased GPR41 levels along with decreased histone deacetylase (HDAC)− 3 levels in mice treated with butyrate. Notably, the effects attributed to acetate, but not butyrate, were nullified when co-administered with the GPR43 antagonist GLPG-0974. T cell priming and differentiation into Th17 cells in MLNs, as well as increased Th17 cell infiltration, were linked to aortic endothelial dysfunction and hypertension subsequent to the transfer of faecal microbiota from IMQ-treated mice to germ-free (GF) mice. These effects were counteracted in GF mice through treatment with either acetate or butyrate. To conclude, these findings underscore the potential of SCFA consumption in averting hypertension by restoring balance to the interplay between the gut, immune system, and vascular wall in SLE induced by TLR7 activation.

Innate Immune System Regulated by Stimulator of Interferon Genes, a Cytosolic DNA Sensor, Regulates Endothelial Function.

Background Sterile inflammation caused by metabolic disorders impairs endothelial function; however, the underlying mechanism by which hyperglycemia induces inflammation remains obscure. Recent studies have suggested that stimulator of interferon genes (STING), a key cytosolic DNA sensor in the innate immune system, contributes to the pathogenesis of inflammatory diseases. This study examines the role of the STING in endothelial dysfunction in streptozotocin-induced diabetic mice. Methods and Results Injection of streptozotocin promoted the expression of STING and DNA damage markers in the aorta of wild-type mice. Streptozotocin elevated blood glucose and lipid levels in both wild-type and STING-deficient mice, which showed no statistical differences. Genetic deletion of STING ameliorated endothelial dysfunction as determined by the vascular relaxation in response to acetylcholine (P<0.001) and increased endothelial nitric oxide synthase phosphorylation in the aorta (P<0.05) in STZ-injected mice. Endothelium-independent vascular response to sodium nitroprusside did not differ. Treatment with a direct STING agonist, cyclic GMP-AMP, or mitochondrial DNA increased inflammatory molecule expression (eg, VCAM1 and IFNB) and decreased endothelial nitric oxide synthase phosphorylation in human umbilical vein endothelial cells, partially through the STING pathway. Cyclic GMP-AMP significantly impaired endothelial function of aortic segments obtained from wild-type mice, which was ameliorated in the presence of C-176, a STING inhibitor, or a neutralizing interferon-β antibody. Furthermore, the administration of C-176 ameliorated endothelial dysfunction in STZ-induced diabetic mice (P<0.01). Conclusions The DNA damage response regulated by STING impairs endothelial function. STING signaling may be a potential therapeutic target of endothelial dysfunction caused by hyperglycemia.

A selective mineralocorticoid receptor blocker, esaxerenone, attenuates vascular dysfunction and inhibits atherogenesis in apolipoprotein e-deficient mice

Abstract Introduction Pharmacological blockade of mineralocorticoid receptors (MR) is a potential therapeutic approach to reduce cardiovascular complications because MR play a crucial role in cardiovascular regulation. Recent studies suggest that MR antagonists affect several extrarenal tissues, including vascular function. We investigated the effects of a novel non-steroidal selective MR blocker, esaxerenone (ESAX), recently approved for hypertension treatment in Japan, on vascular function and the development of atherosclerosis. Methods and results ESAX (3mg/kg/day) or vehicle was orally administered to western type diet-fed apolipoprotein E-deficient mice for 20 weeks or for 8 weeks to investigate the effects on atherogenesis or vascular dysfunction. Administration of ESAX for 20 weeks suppressed the development of atherosclerotic plaques in the aortic arch compared with the vehicle group (p&amp;lt;0.001) without alteration of blood pressure. In addition, ESAX reduced the expression of intercellular cell adhesion molecule-1 (p&amp;lt;0.05), macrophage infiltration (p&amp;lt;0.01), lipid deposition (p&amp;lt;0.05) and tended to decrease the expression of vascular cell adhesion molecule-1 as determined by immunohistochemical analysis. Moreover, phosphorylation of eNOSSer1177 (p&amp;lt;0.05) and Akt (p&amp;lt;0.05) were increased in the aorta of ESAX-treated mice. Administration of ESAX for 8 weeks attenuated western type diet-induced endothelial dysfunction (p&amp;lt;0.05) accompanied with the decrease in expression of ICAM1 (p&amp;lt;0.05) and phosphorylation of JNK (p&amp;lt;0.05) in the descending aorta. In in vitro experiment, aldosterone decreased the phosphorylation of eNOSSer1177 and increased the phosphorylation of eNOSThr495 in a dose dependent manner, which were attenuated by ESAX in HUVECs. In ex vivo vascular reactivity assay, ESAX diminished the aldosterone-induced endothelial dysfunction. Conclusion ESAX ameliorated hyperlipidemia-induced atherosclerosis and vascular dysfunction in mice, suggesting that ESAX is a promising therapeutic approach for cardiovascular complications.

Characterisation of pomegranate juice polyphenols identifies oenothein B as an endothelium-dependent vasodilator and regulator of endothelial function that enhances actions of oligomeric procyanidins

Abstract Background Cardiovascular disease mortality is reduced in individuals with high daily consumption of dietary polyphenols. Optimal daily intakes, choice of polyphenol, and mechanism of action have yet to be fully defined. Pomegranate juice (PJ) reduces blood pressure and improves endothelial function. These effects are attributed to the high levels of polyphenols, primarily ellagitannins. Purpose The aims of these investigations were (1) to identify PJ polyphenol(s) that altered endothelial function and could potentially lower blood pressure, and (2) to compare these endothelial actions to oligomeric procyanidins (OPC) purified from apple polyphenol extracts. Methods PJ polyphenols were purified by Sephadex LH-20 chromatography and RP-HPLC, and identified by LC-MS/MS and NMR. Fractions were screened for biological activity using cultured bovine aortic endothelial cells by measuring the degree of inhibition of endothelin-1 synthesis. Endothelial actions were further assessed by measuring changes in intracellular Ca2+ using FLIPR Ca2+-6 assay, qRT-PCR (EDN1, eNOS and KLF2 mRNAs), and NO synthesis (nitrite). Results Six PJ polyphenols were isolated. These were identified as punicalin, four punicalagin isomers, and oenothein B (OTB, a cyclic dimeric ellagitannin; LC-MS [M-H]-= 1567.1). At concentrations ≤5 µg/ml only OTB inhibited ET-1 synthesis (IC50 1.5 µg/ml). The identity of OTB was confirmed by NMR, and by comparison with OTB purified from Epilobium species. Further characterisation of the actions of OTB on endothelial cells showed pre-incubation with 1.25, 2.5 and 5 µg/ml OTB increased binding of biotinylated-OPC by 1.7, 2.3 and 3.8 fold. Subsequent studies of the interactions between OTB and OPC showed synergistic effects for decreases in ET-1 synthesis, EDN1 mRNA, and increases in KLF2 mRNA, eNOS mRNA and NO release. The effect of combining OTB (1 µg/ml) and OPC (1 µg/ml) lasted for over 24 h (relative to control: ET-1 -57%, EDN1 mRNA -63%, eNOS mRNA +69%, KLF2 mRNA +356%), when individually these polyphenols no longer had any significant effect. Intracellular Ca2+ responses also showed synergistic interactions, however the profile of [Ca2+] changes for OTB and OPC alone differed, suggesting separate signalling pathways initiating these endothelial responses. Endothelium-dependent vasodilator effects of OTB were confirmed on isolated mouse aorta (EC50 0.27 µg/ml). Conclusions These effects of OTB may underlie previously reported decreases in blood pressure and improvements in endothelial function after pomegranate juice consumption. Detailed understanding of the mechanism of action of OTB, and its interactions with OPC could lead to new therapeutic modalities for treating endothelial dysfunction in a broad spectrum of people at risk of cardiovascular disease.

Biomimetic Nanocarriers of Pro-Resolving Lipid Mediators for Resolution of Inflammation in Atherosclerosis.

Atherosclerosis (ATH) is a systemic disease characterized by a chronic inflammatory process and lipid deposition in the arterial walls. The chronic inflammation within ATH lesions results, at least in part, from the failed resolution of inflammation. This process is controlled actively by specialized pro-resolving lipid mediators (SPMs), namely lipoxins, resolvins, protectins, and maresins. Herein, biomimetic nanocarriers are produced comprising a cocktail of SPMs-loaded lipid nanoemulsions (LN) covered with macrophage membranes (Bio-LN/SPMs). Bio-LN/SPMs retain on their surface the macrophage receptors involved in cellular interactions and the "marker of self" CD47, which impede their recognition and uptake by other macrophages. The binding of Bio-LN/SPMs to the surface of endothelial cells (EC) and smooth muscle cells (SMC) is facilitated by the receptors on the macrophage membranes and partly by SPMs receptors. In addition, Bio-LN/SPMs prove functional by reducing monocyte adhesion and transmigration to/through activated EC and by stimulating macrophage phagocytic activity. After intravenous administration, Bio-LN/SPMs accumulate in the aorta of ApoE-deficient mice at the level of atherosclerotic lesions. Also, the safety assessment testing reveals no side effects or immunotoxicity of Bio-LN/SPMs. Thus, the newly developed Bio-LN/SPMs represent a reliable targeted nanomedicine for the resolution of inflammation in atherosclerosis.

Abstract 18625: Mechano-Transcriptomic Interaction Mediates Spatial Variations in Early Vascular Fibrosis

Background: The spatiotemporal variations of wall shear stress (WSS) modulate vascular genomics and function. Despite the advances in imaging modalities and computational modeling, the link between local hemodynamics and genetic pathways underlying atherosclerosis development remains elusive. We hypothesized that differential WSS patterns in the aorta modulate fibroblast gene expression in response to high fat diet (HFD) leading to vascular stiffness. Methods: We performed ultrasound-based 4-D+time moving boundary computational fluid dynamics (CFD) on the aorta of Ldlr -/- mice fed a normal diet (ND) or HFD during 4 weeks. B-mode images (Vevo 3100) of the aortic arch were used to reconstruct a 3-D model of the lumen structure by revolving the vessel wall around the centerline in the aorta and the branches. Computational domain reconstruction was followed by image registration to generate a moving boundary model. WSS contours and velocity profiles were acquired by solving Navier-Stokes equations using svFSI code. The longitudinal strains along the outer curvature of the aortic arch over several cardiac cycles were measured, and the changes were compared with the effects of HFD. Mouse aortas were processed for single cell RNA sequencing and analyzed using the Scanpy package. Results and Conclusion: Our analysis of transcriptomics profiles revealed increased Acta2 and Postn expression in the myofibroblast subclusters, suggesting myofibroblast differentiation in response to HFD in the aortic arch. This was confirmed and localized to the lesser curvature of the aortic arch through Periostin immunostaining. We found that the increase in Postn and Acta2 is associated with reduced arterial strain or increased arterial stiffness measured in the aortic arch. In parallel, CFD analysis demonstrated that an elevated WSS along the outer curvature vs. low WSS and disturbed flow along the inner curvature in early diastole results in differential gene expression to regulate myofibroblast differentiation and modulates vascular stiffness.

Abstract 15041: Single-Cell RNA Sequencing Reveals Four Distinctive Endothelial Subpopulations Through Mouse Endothelial Aging

Introduction: Endothelial cell (EC) dysfunction is a hallmark of vascular aging, contributing to age-related vascular diseases. Elucidating EC aging at the single cell level has significant scientific and therapeutic potential. Research Question: What is the landscape of EC aging at the single cell level? Methods: Mouse aortas were harvested from 1-, 10-, and 20 month-old mice (n=2 males and 2 females at each time point). Pooled single-cell suspensions were prepared, and PECAM1+ cells were enriched by magnetic-activated cell sorting. Results: Single cell RNA sequencing revealed 879 ECs, categorized into six subpopulations (EC 1-6). Of the three canonical EC markers ( Pecam1 , Cdh5, and Kdr ) EC1 and 2 showed higher expression of Pecam1 , whereas EC3 and 4 showed higher expression of Cdh5 and Kdr . ECs from young (1 month-old), middle-aged (10 month-old), and elderly mice (20 month-old) were enriched in EC1, EC3, and EC4, respectively. Gene regulatory network analysis identified specific regulons for each EC subcluster. EC1 displayed progenitor-like features ( Isl1 as one of the top regulons, Procr and Cd34 as highly expressed genes) with high angiogenic potential ( Twist1 as one of the top regulons, Timp2 , Mmp14 , and Mmp2 as highly expressed genes) and the longest G1 phase suggesting its quiescence. EC3 cells exhibited high proliferative status demonstrated by G2M or S phase, accompanied by upregulation of stress-responsive TF Atf3 and NF-κB family members. EC4 demonstrated pronounced Pparg regulon activity. Genes directly regulated by Pparg ( Scarb1 and Cd36 ), and genes involved in fatty acid metabolism and atherogenesis ( Tcf15 , Fabp4 , Gpihbp1 , Lpl , and Meox2) were highly expressed in EC4 and EC3. Conclusions: Our analysis identified four distinct EC subpopulations through the aging process of mouse aortic ECs: EC1, Pecam1 h progenitor-like EC; EC2, Pecam1 h common EC; EC3, Cdh5 h Kdr h inflammatory atherogenic EC; and EC4, Cdh5 h Kdr h non-inflammatory atherogenic EC.

Abstract 18753: Dynamic Phenotypic Transition of Smooth Muscle Cells During Human Ascending Thoracic Aortic Disease Progression: From Compensation in Aortic Aneurysm to Decompensation in Aortic Dissection

Introduction: Although ascending thoracic aortic aneurysm (ATAA) and ascending thoracic aortic dissection (ATAD) share common pathologic features of aortic degeneration, the specific elements that lead to rapid disease progression in ATAD remain poorly understood. We examined the molecular and cellular dynamics in smooth muscle cells (SMCs) of aortic tissues from ATAA and ATAD patients and further examined mechanisms in a mouse model. Methods: Single-cell RNA sequencing (scRNA-seq) analyses were performed in ascending aortic tissues from individuals without aortic disease (n=8), patients with ATAA without dissection (n=9), and patients with acute ATAD (n=9). Further, scRNA-seq and scATAC-seq were performed in ascending aortic tissues from mice infused with angiotensin II (AngII) or control mice; scRNA-seq analyses were performed on SMC-specific Tgfbr2 -/- mice. Results: Six SMC subtypes were identified in human aortic tissues. Cluster proportion and trajectory analyses indicated a profound SMC transition from contractile in control to extracellular matrix (ECM)-contractile phenotype in ATAA, however, was reduced in ATAD tissues. Instead, ATAD showed significant SMC transition to inflammatory phenotype. Consistently, many genes in ECM organization and muscle contraction, collectively termed compensatory response, were upregulated in ATAA but downregulated in ATAD tissues compared with controls, whereas inflammatory response and cell death pathway genes were significantly upregulated in ATAD compared with control and ATAA tissues. Cell-cell interaction, regulatory network, and motif analysis suggested that TGF-beta-MEF2C signaling contributed to the induction of the ECM-contractile SMC phenotype. MEF2C + SMCs exhibited the capacity of transition towards ECM-producing SMCs in both mouse and human aorta. SMC-specific Tgfbr2 -/- mice showed compromised SMC transition to ECM-producing phenotype. Conclusions: Our study reveals SMC phenotypic transitions to ECM-producing SMCs in ATAA and to inflammatory and pro-death SMCs in ATAD, which represent a compensatory response in ATAA and a decompensatory status in ATAD. TGF-beta-MEF2C, a novel regulatory axis, promoted the compensatory response in SMCs of the ascending aorta.

Abstract 15060: Inhibition of Endoplasmic Reticulum Stress and YAP/TAZ Signaling Protects Endothelial Function in Diabetes

Introduction: Previous studies have demonstrated the role of Hippo pathway with its major effectors, Yes-associated protein (YAP) and transcription activator with PDZ binding motif (TAZ) in atherosclerosis. However, the involvement of YAP/TAZ signaling in diabetes-associated endothelial dysfunction remains unexplored. Hypothesis: We hypothesized that activation of YAP/TAZ signaling links with endoplasmic reticulum (ER) stress and contributes to endothelial dysfunction. Methods: Male C57BL/6 mice were fed with high-fat diet, 45% kcal% fat for 15 weeks to induce obesity and diabetes. ER stress alleviator 4-phenylbutyric acid was orally administered for 4 weeks at 100 mg/kg/day. Vascular reactivity of mouse aortas was assessed by wire myograph. Human umbilical vein endothelial cells (HUVECs) were cultured with risk factors such as high glucose and ER stress inducer tunicamycin. Western blot and immunofluorescent staining were performed to evaluate the expressions of protein targets. Results: YAP/TAZ signaling was activated accomplished with ER stress in aortas from obese diabetic mice and in endothelial cells treated with risk factors. Chronic treatment with 4-phenylbutyric acid ameliorated endothelium-dependent relaxations as well as inhibited ER stress, YAP/TAZ signaling and oxidative stress in aortas. Phosphorylation of YAP at Ser127 was reduced in mouse aortic arch which was downregulated by ER stress alleviator. In HUVECs, ER stress alleviators significantly inhibited YAP/TAZ signaling and increased NO bioavailability but YAP inhibitor did not suppress ER stress. Conclusions: ER stress activates YAP/TAZ signaling, resulting in endothelial dysfunction in diabetes. Inhibition of YAP/TAZ is vasoprotective and exhibits therapeutic potential against diabetic vascular complication.

Abstract 15774: Cu Uptake Transporter CTR1 Cys189 Oxidation Protects Against Atherosclerosis via Limiting Mitochondrial Dysfunction and Endothelial Senescence

Background: Copper (Cu) is an essential micronutrient, but excess Cu is toxic. Role of copper in atherosclerosis remains unclear. The major Cu-uptake transporter CTR1 provides Cu to Cu chaperone/transcription factor Atox1 to promote inflammation as well as mitochondrial cytochrome C oxidase (COX) to regulate mitochondrial (mito)function. We reported that growth factor VEGF induced CTR1 Cys189 oxidation promotes VEGFR2/CTR1 internalization and angiogenesis in endothelial cells (ECs) while excess Cu induces CTR1 internalization to prevent Cu toxicity. However, role of CTR1-Cys189 in ROS-dependent mito dysfunction and senescence in ECs involved in atherosclerosis remains unknown. Results: Here we showed that inducible EC-specific Ctr1 -/- /ApoE -/- mice with high fat diet (HFD) reduced atherosclerosis (72%) and Mac3+ inflammatory cell (62%) vs. atherosclerotic ApoE -/- /HFD mice aorta which showed Ctr1-CysOH formation vs. control ApoE -/- mice. CRISPR-generated “redox-dead” Ctr1-Cys189A knock-in ApoE -/- /HFD mice aorta inhibited Ctr1-CysOH formation but enhanced atherosclerotic lesions and Cu accumulation (ICP-MS) vs. ApoE -/- /HFD mice. This in turn enhanced senescence (β-gal and markers), DNA oxidation, macrophage recruitment and mitochondrial hyperfusion (by TEM). In cultured human EC, proatherogenic cytokine TNFα stimulation rapidly induced CTR1-CysOH formation and CTR1 internalization, which were inhibited by CTR1-C189A or Nox4 shRNA. CTR1-C189A overexpression increased intracellular Cu and its downstream p-Drp1-S637 that promotes mitochondrial hyperfusion, mito dysfunction and mitoROS. This was associated with CTR1-C189A binding to mito Cu transporter SLC25A3, which might facilitate mito Cu overload and mito dysfunction. These CTR1-C189A-induced responses were inhibited by Cu chelator TTM and mito O 2 - scavenger Mito-TEMPO. Conclusions: CTR1-Cys189 oxidation-induced internalization limits excess Cu entry to protect against pro-atherogenic phenotype of CTR1/Cu. Preventing CTR1-Cys189 oxidation increases mito dysfunction via enhancing novel Cu-pS637-Drp1 axis as well as CTR1-SLC25A3 axis, which promotes mitoROS and EC senescence, thereby accelerating atherosclerosis.

MiR-22 inhibits angiotensin II-induced aortic dissection and protects aortic vessel wall in mice by targeting MAPK14

Purpose: To study the effect of miR-22 on angiotensin II-induced aortic dissection in mice, and its protective effect on aortic vessel wall, as well the involvement of MAPK-14 in these processes.&#x0D; Methods: A mouse aortic dissection model was established via subcutaneous implantation of angiotensin II (1 µg/kg/min) micropump in the dorsal region. The mice (n = 30) were assigned in equal numbers to 5 groups (n = 6). All injections were given via the tail vein. The miR-22 expressions in aortas of mice in each group were determined with quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Western blot assay was used to determine the expressions of MAPK-14 protein, while H&amp;E staining was used to measure the ratio of aortic thickness-to-diameter, and contents of collagen and elastic fibers.&#x0D; Results: The expression of miR-22 in aorta of mice in miR-22 overexpression group was significantly higher than that in overexpression control group, but significantly lower in miR-22 inhibition mouse than in inhibition control mouse (p &lt; 0.05). There was significantly lower protein expression of MAPK-14 in mice aorta in miR-22 overexpression mice than in overexpression control mice, but significantly upregulated in miR-22 inhibition mice, relative to that in inhibition control mice (p &lt; 0.05). In the miR-22 overexpression mice, the ratio of membrane thickness-to-diameter was higher than the corresponding value in miR-22 inhibition mice. There were significantly higher contents of aortic elastic and collagen fibers in miR-22 overexpression mice than in overexpression control and miR-22 inhibition groups (p &lt; 0.05).&#x0D; Conclusion: Overexpression of miR-22 inhibits the up-regulation of expression of its target gene mapk14, increases thickness of aortic media and aortic elasticity in mice, and increase the content of collagen fibers, thereby exerting protective effect on aortic wall structure.

Interference of MDM2 attenuates vascular endothelial dysfunction in hypertension partly through blocking Notch1/NLRP3 inflammasome pathway

BackgroundHypertension is a life-threatening disease mainly featured as vascular endothelial dysfunction. This study aims to explore the regulatory role of murine double minute 2 (MDM2) in hypertension and vascular damage. MethodsMice were infused with angiotensin II (AngII) to establish a hypertension mouse model in vivo and AngII-stimulated HUVECs were constructed to simulate the damage of vascular endothelial cells in hypertension in vitro. The plasmids targeting to MDM2 was injected to mice or transfected to HUVECs. qRT-PCR and western blot were performed to detect corresponding gene expression in mice aorta. Blood pressure was measured. H&E and Masson staining were conducted to evaluate histological changes of aorta. Responses to the acetylcholine (ACh) and sodium nitroprusside (SNP) were assessed in aorta. ZO-1 expression and cell apoptosis were detected by immunofluorescence and TUNEL, respectively. Network formation ability was determined employing a tube formation. ResultsMDM2 was upregulated in hypertensive mice. Knockdown of MDM2 inhibited AngII-induced high BP, histological damage, vascular relaxation to Ach, and promoted the levels of p-eNOS and ZO-1 in the aorta in hypertensive mice. MDM2 knockdown inactivated Notch1 signaling and NLRP3 inflammasome, while the inhibitory effect of MDM2 knockdown on NLRP3 inflammasome activation was partly restored by the activation of Notch1. Furthermore, knockdown of MDM2 relieved AngII-induced endothelial dysfunction in HUVECs, as well as suppressing AngII-promoted cell apoptosis. Whereas, the impacts generated by MDM2 knockdown were partly weakened by the activation of Notch1 signaling or NLRP3 inflammasome. ConclusionIn summary, knockdown of MDM2 can attenuate vascular endothelial dysfunction in hypertension, which may be achieved through inhibiting the activation of Notch1 and NLRP3 inflammasome.

Selenium Deficiency Promotes Dilatation of the Aorta by Increasing Expression and Activity of Vascular Smooth Muscle Cell Derived Matrix Metalloproteinase-2

Selenium (Se) is a key part of the body's oxidation defence system. However, it is unclear whether Se affects the development of aortic aneurysm (AA). An animal experiment was conducted to clarify the role of Se in AA development. C57BL/6N male mice were fed with a Se deficient (Se-D, < 0.05 mg/kg), Se adequate (Se-A, 0.2 mg/kg), or Se supplemented (Se-S, 1 mg/kg) diet for 8 weeks. Subsequently, an AA murine model (Se-D, n= 11; Se-A, n= 12; Se-S, n= 15) was established using angiotensin II (Ang II, 1 mg/kg/min) for four weeks plus β-aminopropionitrile (BAPN, 1 mg/mL) for the first two weeks. Saline replaced Ang II, and BAPN was removed during the modelling process for sham mice (Se-A, n= 9). To determine whether Se deficiency promoted aortic dilation via matrix metalloproteinase-2 (MMP-2), the non-specific MMP inhibitor doxycycline (Dox, 100 mg/kg/day) was given to Se-D AA mice (n= 7) for two weeks. The maximum aortic diameter in Se-D AA model mice was significantly increased compared with Se-A AA model mice. MMP-2 expression and activity in the aortic media of Se-D AA model mice was significantly increased compared with Se-A AA model mice. A large number of vascular smooth muscle cells (VSMCs) were found aggregating in the media of the non-dilated aorta of Se-D AA model mice, which was completely inhibited by Dox. The percentage of VSMCs in aortic media of Se-D AA model mice was significantly higher than in Se-A AA model mice. The maximum aortic diameter and occurrence rate of AA in Se-D AA model mice with Dox were significantly reduced compared with Se-D AA model mice. Se deficiency promoted dilatation of the aorta in AA model mice by increasing expression and activity of VSMC derived MMP-2, causing abnormal aggregation and proliferation of VSMCs in aortic media.

LITAF Promotes Atherosclerotic Plaque Formation by Stimulating the NF-κB Inflammatory Pathway.

Lipopolysaccharide-induced tumor necrosis factor-α factor (LITAF) protein is a newly discovered inflammatory protein. This study aims to study the role of LITAF in the formation of atherosclerosis. A total of 10 C57BL/6J mice and 10 C57BL/6J mice with knockout of LITAF gene (C57BL/6J-LITAF-) were divided into two groups: the control group and the LITAF-/- group. The animals were accommodated for 16 weeks and then euthanized with their hearts and aortas isolated thereafter. Next, the roots of the mouse aorta were cryosectioned and stained with Oil Red O staining and immunohistochemical staining (CD68, α-SMA, and Masson), respectively. The area of Oil Red O staining and the proportion of positive expression after immunohistochemical staining were then compared between the control and LITAF-/- groups. At the same time, the blood of mice was collected for the extraction of proteins and RNA. The proteins and RNA were used to detect the expression of major molecules of the NF-κB inflammatory pathway in mice in the control group and the LITAF-/- group by Western blotting and RT-PCR. Oil Red O staining of the aortic root sections of the mice in each group revealed that the area of atherosclerotic plaques in the LITAF-/- group was substantially lower than that in the control group (P<0.05). Moreover, immunohistochemical staining determined that the expression level of α-SMA and CD68 in the LITAF-/- group was significantly lower than that in the control group, whereas the results were reversed following Masson staining (P<0.05). The expression levels of P65 and caspase 3 were significantly lower in the LITAF-/- group than in the control group (P<0.05), whereas the expression level of IκB was higher in the LITAF-/- group. LITAF might participate in the formation of atherosclerotic plaque through the NF-κB pathway and play a promoting role in the formation of atherosclerosis.