RESUMO
The onset of venous thromboembolism, including pulmonary embolism, represents a significant health burden affecting more than 1 million people annually worldwide. Current treatment options are based on anticoagulation, which is suboptimal for preventing further embolic events. In order to develop better treatments for thromboembolism, we sought to understand the structural and mechanical properties of blood clots and how this influences embolism in vivo. We developed a murine model in which fibrin γ-chain cross-linking by activated Factor XIII is eliminated (FGG3X) and applied methods to study thromboembolism at whole-body and organ levels. We show that FGG3X mice have a normal phenotype, with overall coagulation parameters and platelet aggregation and function largely unaffected, except for total inhibition of fibrin γ-chain cross-linking. Elimination of fibrin γ-chain cross-linking resulted in thrombi with reduced strength that were prone to fragmentation. Analysis of embolism in vivo using Xtreme optical imaging and light sheet microscopy demonstrated that the elimination of fibrin γ-chain cross-linking resulted in increased embolization without affecting clot size or lysis. Our findings point to a central previously unrecognized role for fibrin γ-chain cross-linking in clot stability. They also indirectly indicate mechanistic targets for the prevention of thrombosis through selective modulation of fibrin α-chain but not γ-chain cross-linking by activated Factor XIII to reduce thrombus size and burden, while maintaining clot stability and preventing embolism.
Assuntos
Reagentes de Ligações Cruzadas/química , Fator XIIIa/metabolismo , Fibrinogênio/metabolismo , Embolia Pulmonar/etiologia , Embolia Pulmonar/patologia , Veia Cava Inferior/patologia , Trombose Venosa/complicações , Animais , Coagulação Sanguínea , Plaquetas/metabolismo , Modelos Animais de Doenças , Camundongos Endogâmicos C57BL , Imagem Óptica , Embolia Pulmonar/sangue , Trombose Venosa/sangueRESUMO
PURPOSE: Tensor-valued diffusion encoding can probe more specific features of tissue microstructure than what is available by conventional diffusion weighting. In this work, we investigate the technical feasibility of tensor-valued diffusion encoding at high b-values with q-space trajectory imaging (QTI) analysis, in the human heart in vivo. METHODS: Ten healthy volunteers were scanned on a 3T scanner. We designed time-optimal gradient waveforms for tensor-valued diffusion encoding (linear and planar) with second-order motion compensation. Data were analyzed with QTI. Normal values and repeatability were investigated for the mean diffusivity (MD), fractional anisotropy (FA), microscopic FA (µFA), isotropic, anisotropic and total mean kurtosis (MKi, MKa, and MKt), and orientation coherence (Cc ). A phantom, consisting of two fiber blocks at adjustable angles, was used to evaluate sensitivity of parameters to orientation dispersion and diffusion time. RESULTS: QTI data in the left ventricular myocardium were MD = 1.62 ± 0.07 µm2 /ms, FA = 0.31 ± 0.03, µFA = 0.43 ± 0.07, MKa = 0.20 ± 0.07, MKi = 0.13 ± 0.03, MKt = 0.33 ± 0.09, and Cc = 0.56 ± 0.22 (mean ± SD across subjects). Phantom experiments showed that FA depends on orientation dispersion, whereas µFA was insensitive to this effect. CONCLUSION: We demonstrated the first tensor-valued diffusion encoding and QTI analysis in the heart in vivo, along with first measurements of myocardial µFA, MKi, MKa, and Cc . The methodology is technically feasible and provides promising novel biomarkers for myocardial tissue characterization.
Assuntos
Imagem de Tensor de Difusão , Coração , Humanos , Imagem de Tensor de Difusão/métodos , Coração/diagnóstico por imagem , Imagem de Difusão por Ressonância Magnética , Miocárdio , Ventrículos do Coração , AnisotropiaRESUMO
BACKGROUND & AIMS: PIEZO1 and TRPV4 are mechanically and osmotically regulated calcium-permeable channels. The aim of this study was to determine the relevance and relationship of these channels in the contractile tone of the hepatic portal vein, which experiences mechanical and osmotic variations as it delivers blood to the liver from the intestines, gallbladder, pancreas and spleen. METHODS: Wall tension was measured in freshly dissected portal veins from adult male mice, which were genetically unmodified or modified for either a non-disruptive tag in native PIEZO1 or endothelial-specific PIEZO1 deletion. Pharmacological agents were used to activate or inhibit PIEZO1, TRPV4 and associated pathways, including Yoda1 and Yoda2 for PIEZO1 and GSK1016790A for TRPV4 agonism, respectively. RESULTS: PIEZO1 activation leads to nitric oxide synthase- and endothelium-dependent relaxation of the portal vein. TRPV4 activation causes contraction, which is also endothelium-dependent but independent of nitric oxide synthase. The TRPV4-mediated contraction is suppressed by inhibitors of phospholipase A2 and cyclooxygenases and mimicked by prostaglandin E2 , suggesting mediation by arachidonic acid metabolism. TRPV4 antagonism inhibits the effect of agonising TRPV4 but not PIEZO1. Increased wall stretch and hypo-osmolality inhibit TRPV4 responses while lacking effects on or amplifying PIEZO1 responses. CONCLUSIONS: The portal vein contains independently functioning PIEZO1 channels and TRPV4 channels in the endothelium, the pharmacological activation of which leads to opposing effects of vessel relaxation (PIEZO1) and contraction (TRPV4). In mechanical and osmotic strain, the PIEZO1 mechanism dominates. Modulators of these channels could present important new opportunities for manipulating liver perfusion and regeneration in disease and surgical procedures.
Assuntos
Canais Iônicos , Óxido Nítrico , Veia Porta , Canais de Cátion TRPV , Animais , Masculino , Camundongos , Endotélio/metabolismo , Óxido Nítrico Sintase/metabolismo , Pressão Osmótica , Canais de Cátion TRPV/genética , Canais de Cátion TRPV/metabolismo , Vasodilatação , Canais Iônicos/genética , Canais Iônicos/metabolismoRESUMO
[Figure: see text].
Assuntos
Tecido Adiposo/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Endotélio Vascular/metabolismo , Glucose/metabolismo , Músculo Esquelético/metabolismo , Comunicação Parácrina , Animais , Células Cultivadas , Humanos , Peróxido de Hidrogênio/metabolismo , Insulina/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/genética , MicroRNAs/metabolismo , NADPH Oxidase 4/genética , NADPH Oxidase 4/metabolismo , Receptor IGF Tipo 1/genética , Receptor IGF Tipo 1/metabolismoRESUMO
Changes in composition of the intestinal microbiota are linked to the development of obesity and can lead to endothelial cell (EC) dysfunction. It is unknown whether EC can directly influence the microbiota. Insulin-like growth factor-1 (IGF-1) and its receptor (IGF-1R) are critical for coupling nutritional status and cellular growth; IGF-1R is expressed in multiple cell types including EC. The role of ECIGF-1R in the response to nutritional obesity is unexplored. To examine this, we use gene-modified mice with EC-specific overexpression of human IGF-1R (hIGFREO) and their wild-type littermates. After high-fat feeding, hIGFREO weigh less, have reduced adiposity and have improved glucose tolerance. hIGFREO show an altered gene expression and altered microbial diversity in the gut, including a relative increase in the beneficial genus Akkermansia. The depletion of gut microbiota with broad-spectrum antibiotics induces a loss of the favourable metabolic differences seen in hIGFREO mice. We show that IGF-1R facilitates crosstalk between the EC and the gut wall; this crosstalk protects against diet-induced obesity, as a result of an altered gut microbiota.
Assuntos
Resistência à Insulina , Microbiota , Animais , Dieta Hiperlipídica/efeitos adversos , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/genética , Receptor IGF Tipo 1/genéticaRESUMO
Insulin resistance leads to excessive endothelial cell (EC) superoxide generation and accelerated atherosclerosis. The principal source of superoxide from the insulin-resistant endothelium is the Nox2 isoform of NADPH oxidase. Here we examine the therapeutic potential of Nox2 inhibition on superoxide generation in saphenous vein ECs (SVECs) from patients with advanced atherosclerosis and type 2 diabetes and on vascular function, vascular damage, and lipid deposition in apolipoprotein E-deficient (ApoE-/-) mice with EC-specific insulin resistance (ESMIRO). To examine the effect of genetic inhibition of Nox2, ESMIRO mice deficient in ApoE-/- and Nox2 (ESMIRO/ApoE-/-/Nox2-/y) were generated and compared with ESMIRO/ApoE-/-/Nox2+/y littermates. To examine the effect of pharmacological inhibition of Nox2, we administered gp91dstat or scrambled peptide to ESMIRO/ApoE-/- mice. SVECs from diabetic patients had increased expression of Nox2 protein with concomitant increase in superoxide generation, which could be reduced by the Nox2 inhibitor gp91dstat. After 12 wk Western diet, ESMIRO/ApoE-/-/Nox2-/y mice had reduced EC superoxide generation and greater aortic relaxation to acetylcholine. ESMIRO/ApoE-/-/Nox2-/y mice developed more lipid deposition in the thoraco-abdominal aorta with multiple foci of elastin fragmentation at the level of the aortic sinus and greater expression of intercellular adhesion molecule-1 (ICAM-1). Gp91dstat reduced EC superoxide and lipid deposition in the thoraco-abdominal aorta of ESMIRO/ApoE-/- mice without causing elastin fragmentation or increased ICAM-1 expression. These results demonstrate that insulin resistance is characterized by increased Nox2-derived vascular superoxide. Complete deletion of Nox2 in mice with EC insulin resistance exacerbates, whereas partial pharmacological Nox2 inhibition protects against, insulin resistance-induced vascular damage.
Assuntos
Diabetes Mellitus/metabolismo , Endotélio Vascular/metabolismo , Glicoproteínas/farmacologia , Resistência à Insulina/fisiologia , NADPH Oxidase 2/antagonistas & inibidores , NADPH Oxidase 2/genética , Idoso , Idoso de 80 Anos ou mais , Animais , Células Cultivadas , Diabetes Mellitus/genética , Diabetes Mellitus/patologia , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/patologia , Feminino , Humanos , Masculino , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Pessoa de Meia-Idade , NADPH Oxidase 2/deficiência , Técnicas de Cultura de ÓrgãosRESUMO
The mechanisms by which physical forces regulate endothelial cells to determine the complexities of vascular structure and function are enigmatic. Studies of sensory neurons have suggested Piezo proteins as subunits of Ca(2+)-permeable non-selective cationic channels for detection of noxious mechanical impact. Here we show Piezo1 (Fam38a) channels as sensors of frictional force (shear stress) and determinants of vascular structure in both development and adult physiology. Global or endothelial-specific disruption of mouse Piezo1 profoundly disturbed the developing vasculature and was embryonic lethal within days of the heart beating. Haploinsufficiency was not lethal but endothelial abnormality was detected in mature vessels. The importance of Piezo1 channels as sensors of blood flow was shown by Piezo1 dependence of shear-stress-evoked ionic current and calcium influx in endothelial cells and the ability of exogenous Piezo1 to confer sensitivity to shear stress on otherwise resistant cells. Downstream of this calcium influx there was protease activation and spatial reorganization of endothelial cells to the polarity of the applied force. The data suggest that Piezo1 channels function as pivotal integrators in vascular biology.
Assuntos
Células Endoteliais/citologia , Células Endoteliais/fisiologia , Fricção , Canais Iônicos/metabolismo , Estresse Mecânico , Animais , Embrião de Mamíferos/irrigação sanguínea , Embrião de Mamíferos/metabolismo , Feminino , Hemorreologia , Masculino , CamundongosRESUMO
RATIONALE: In the endothelium, insulin stimulates endothelial NO synthase (eNOS) to generate the antiatherosclerotic signaling radical NO. Insulin-resistant type 2 diabetes mellitus is associated with reduced NO availability and accelerated atherosclerosis. The effect of enhancing endothelial insulin sensitivity on NO availability is unclear. OBJECTIVE: To answer this question, we generated a mouse with endothelial cell (EC)-specific overexpression of the human insulin receptor (hIRECO) using the Tie2 promoter-enhancer. METHODS AND RESULTS: hIRECO demonstrated significant endothelial dysfunction measured by blunted endothelium-dependent vasorelaxation to acetylcholine, which was normalized by a specific Nox2 NADPH oxidase inhibitor. Insulin-stimulated phosphorylation of protein kinase B was increased in hIRECO EC as was Nox2 NADPH oxidase-dependent generation of superoxide, whereas insulin-stimulated and shear stress-stimulated eNOS activations were blunted. Phosphorylation at the inhibitory residue Y657 of eNOS and expression of proline-rich tyrosine kinase 2 that phosphorylates this residue were significantly higher in hIRECO EC. Inhibition of proline-rich tyrosine kinase 2 improved insulin-induced and shear stress-induced eNOS activation in hIRECO EC. CONCLUSIONS: Enhancing insulin sensitivity specifically in EC leads to a paradoxical decline in endothelial function, mediated by increased tyrosine phosphorylation of eNOS and excess Nox2-derived superoxide. Increased EC insulin sensitivity leads to a proatherosclerotic imbalance between NO and superoxide. Inhibition of proline-rich tyrosine kinase 2 restores insulin-induced and shear stress-induced NO production. This study demonstrates for the first time that increased endothelial insulin sensitivity leads to a proatherosclerotic imbalance between NO and superoxide.
Assuntos
Aterosclerose/metabolismo , Células Endoteliais/metabolismo , Endotélio Vascular/metabolismo , Resistência à Insulina/fisiologia , Transdução de Sinais/fisiologia , Animais , Aterosclerose/patologia , Células Cultivadas , Células Endoteliais/patologia , Endotélio Vascular/patologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Técnicas de Cultura de ÓrgãosRESUMO
OBJECTIVE: Vascular endothelial growth factor (VEGF) acts, in part, by triggering calcium ion (Ca(2+)) entry. Here, we sought understanding of a Synta66-resistant Ca(2+) entry pathway activated by VEGF. APPROACH AND RESULTS: Measurement of intracellular Ca(2+) in human umbilical vein endothelial cells detected a Synta66-resistant component of VEGF-activated Ca(2+) entry that occurred within 2 minutes after VEGF exposure. Knockdown of the channel-forming protein Orai3 suppressed this Ca(2+) entry. Similar effects occurred in 3 further types of human endothelial cell. Orai3 knockdown was inhibitory for VEGF-dependent endothelial tube formation in Matrigel in vitro and in vivo in the mouse. Unexpectedly, immunofluorescence and biotinylation experiments showed that Orai3 was not at the surface membrane unless VEGF was applied, after which it accumulated in the membrane within 2 minutes. The signaling pathway coupling VEGF to the effect on Orai3 involved activation of phospholipase Cγ1, Ca(2+) release, cytosolic group IV phospholipase A2α, arachidonic acid production, and, in part, microsomal glutathione S-transferase 2, an enzyme which catalyses the formation of leukotriene C4 from arachidonic acid. Shear stress reduced microsomal glutathione S-transferase 2 expression while inducing expression of leukotriene C4 synthase, suggesting reciprocal regulation of leukotriene C4-synthesizing enzymes and greater role of microsomal glutathione S-transferase 2 in low shear stress. CONCLUSIONS: VEGF signaling via arachidonic acid and arachidonic acid metabolism causes Orai3 to accumulate at the cell surface to mediate Ca(2+) entry and downstream endothelial cell remodeling.
Assuntos
Aterosclerose/genética , Canais de Cálcio/genética , Cálcio/metabolismo , Regulação da Expressão Gênica , RNA/genética , Fator A de Crescimento do Endotélio Vascular/genética , Remodelação Vascular/genética , Animais , Aterosclerose/metabolismo , Aterosclerose/patologia , Canais de Cálcio/biossíntese , Movimento Celular , Células Cultivadas , Modelos Animais de Doenças , Células Endoteliais da Veia Umbilical Humana , Humanos , Immunoblotting , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Nus , Reação em Cadeia da Polimerase em Tempo Real , Transdução de Sinais , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Recent data suggest reduced indices of vascular repair in South Asian men, a group at increased risk of cardiovascular events. Outgrowth endothelial cells (OEC) represent an attractive tool to study vascular repair in humans and may offer potential in cell-based repair therapies. We aimed to define and manipulate potential mechanisms of impaired vascular repair in South Asian (SA) men. In vitro and in vivo assays of vascular repair and angiogenesis were performed using OEC derived from SA men and matched European controls, prior defining potentially causal molecular mechanisms. SA OEC exhibited impaired colony formation, migration, and in vitro angiogenesis, associated with decreased expression of the proangiogenic molecules Akt1 and endothelial nitric oxide synthase (eNOS). Transfusion of European OEC into immunodeficient mice after wire-induced femoral artery injury augmented re-endothelialization, in contrast with SA OEC and vehicle; SA OEC also failed to promote angiogenesis after induction of hind limb ischemia. Expression of constitutively active Akt1 (E17KAkt), but not green fluorescent protein control, in SA OEC increased in vitro angiogenesis, which was abrogated by a NOS antagonist. Moreover, E17KAkt expressing SA OEC promoted re-endothelialization of wire-injured femoral arteries, and perfusion recovery of ischemic limbs, to a magnitude comparable with nonmanipulated European OEC. Silencing Akt1 in European OEC recapitulated the functional deficits noted in SA OEC. Reduced signaling via the Akt/eNOS axis is causally linked with impaired OEC-mediated vascular repair in South Asian men. These data prove the principle of rescuing marked reparative dysfunction in OEC derived from these men.
Assuntos
Vasos Sanguíneos/patologia , Células Endoteliais/citologia , Células Endoteliais/enzimologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Cicatrização , Adulto , Animais , Ásia , Demografia , Células Endoteliais/efeitos dos fármacos , Inativação Gênica , Humanos , Insulina/farmacologia , Masculino , Camundongos Nus , Fosforilação/efeitos dos fármacos , Fatores de Risco , População Branca , Cicatrização/efeitos dos fármacosRESUMO
OBJECTIVES: Defective endothelial regeneration predisposes to adverse arterial remodeling and is thought to contribute to cardiovascular disease in type 2 diabetes mellitus. We recently demonstrated that the type 1 insulin-like growth factor receptor (IGF1R) is a negative regulator of insulin sensitivity and nitric oxide bioavailability. In this report, we examined partial deletion of the IGF1R as a potential strategy to enhance endothelial repair. APPROACH AND RESULTS: We assessed endothelial regeneration after wire injury in mice and abundance and function of angiogenic progenitor cells in mice with haploinsufficiency of the IGF1R (IGF1R(+/-)). Endothelial regeneration after arterial injury was accelerated in IGF1R(+/-) mice. Although the yield of angiogenic progenitor cells was lower in IGF1R(+/-) mice, these angiogenic progenitor cells displayed enhanced adhesion, increased secretion of insulin-like growth factor-1, and enhanced angiogenic capacity. To examine the relevance of IGF1R manipulation to cell-based therapy, we transfused IGF1R(+/-) bone marrow-derived CD117(+) cells into wild-type mice. IGF1R(+/-) cells accelerated endothelial regeneration after arterial injury compared with wild-type cells and did not alter atherosclerotic lesion formation. CONCLUSIONS: Haploinsufficiency of the IGF1R is associated with accelerated endothelial regeneration in vivo and enhanced tube forming and adhesive potential of angiogenic progenitor cells in vitro. Partial deletion of IGF1R in transfused bone marrow-derived CD117(+) cells enhanced their capacity to promote endothelial regeneration without altering atherosclerosis. Our data suggest that manipulation of the IGF1R could be exploited as novel therapeutic approach to enhance repair of the arterial wall after injury.
Assuntos
Doenças das Artérias Carótidas/prevenção & controle , Endotélio Vascular/fisiologia , Artéria Femoral/lesões , Células-Tronco Hematopoéticas/fisiologia , Neovascularização Fisiológica/fisiologia , Receptor IGF Tipo 1/fisiologia , Animais , Aorta Torácica/patologia , Apolipoproteínas E/deficiência , Doenças das Artérias Carótidas/etiologia , Doenças das Artérias Carótidas/genética , Adesão Celular , Endotélio Vascular/metabolismo , Feminino , Regulação da Expressão Gênica , Genótipo , Transplante de Células-Tronco Hematopoéticas , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Óxido Nítrico Sintase Tipo III/metabolismo , Fenótipo , Fosforilação , Processamento de Proteína Pós-Traducional , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Receptor IGF Tipo 1/deficiência , Receptor IGF Tipo 1/genética , RegeneraçãoRESUMO
Heart failure with preserved ejection fraction (HFpEF) is a major clinical problem, with limited treatments. HFpEF is characterized by a distinct, but poorly understood, skeletal muscle pathology, which could offer an alternative therapeutic target. In a rat model, we identified impaired myonuclear accretion as a mechanism for low myofiber growth in HFpEF following resistance exercise. Acute caloric restriction rescued skeletal muscle pathology in HFpEF, whereas cardiac therapies had no effect. Mechanisms regulating myonuclear accretion were dysregulated in patients with HFpEF. Overall, these findings may have widespread implications in HFpEF, indicating combined dietary with exercise interventions as a beneficial approach to overcome skeletal muscle pathology.
RESUMO
High fat diet (HFD)-induced obesity leads to perturbation in the storage function of white adipose tissue (WAT) resulting in deposition of lipids in tissues ill-equipped to deal with this challenge. The role of insulin like growth factor-1 (IGF-1) in the systemic and organ-specific responses to HFD is unclear. Using cixutumumab, a monoclonal antibody that internalizes and degrades cell surface IGF-1 receptors (IGF-1 R), leaving insulin receptor expression unchanged we aimed to establish the role of IGF-1 R in the response to a HFD. Mice treated with cixutumumab fed standard chow developed mild hyperinsulinemia with no change in WAT. When challenged by HFD mice treated with cixutumumab had reduced weight gain, reduced WAT expansion, and reduced hepatic lipid vacuole formation. In HFD-fed mice, cixutumumab led to reduced levels of genes encoding proteins important in fatty acid metabolism in WAT and liver. Cixutumumab protected against blunting of insulin-stimulated phosphorylation of Akt in liver of HFD fed mice. These data reveal an important role for IGF-1 R in the WAT and hepatic response to short-term nutrient excess. IGF-1 R inhibition during HFD leads to a lipodystrophic phenotype with a failure of WAT lipid storage and protection from HFD-induced hepatic insulin resistance.
Assuntos
Resistência à Insulina , Receptor IGF Tipo 1 , Tecido Adiposo/metabolismo , Tecido Adiposo Branco/metabolismo , Animais , Anticorpos Monoclonais Humanizados , Dieta Hiperlipídica/efeitos adversos , Insulina/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Lipídeos , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/etiologia , Obesidade/metabolismo , Receptor IGF Tipo 1/antagonistas & inibidoresRESUMO
OBJECTIVE: Previously published work has indicated that transcripts encoding transglutaminase 2 (TG2) increase markedly in a rat model of abdominal aortic aneurysm. This study determines whether TG2 and the related TG, factor XIII-A (FXIII-A), protect against aortic aneurysm development in mice. METHODS: C57BL/6J wild-type, Tgm2 -/- knockout, F13a1 -/- knockout, and Tgm2 -/- /F13a1 -/- double knockout mice were subjected to laparotomy and periaortic application of CaCl2. RESULTS: Tgm2 -/- mice showed slightly greater aortic dilatation at 6 weeks after treatment when compared with wild type. However, vessels from Tgm2 -/- mice, but not wild-type mice, continued to dilate up to 6 months after injury and by 24 weeks, a greater number of Tgm2 -/- mice had developed aneurysms (16/17 vs 10/19; P = .008). Laparotomy resulted in a high death rate in F13a1 -/- knockout mice, more frequently from cardiac complications than from hemorrhage, but among F13a1 -/- mice that survived for 6 weeks after CaCl2 treatment, abdominal aortic aneurysm diameter was unaltered relative to wild-type mice. Laparotomy resulted in a higher death rate among Tgm2 -/- /F13a1 -/- double knockout mice, owing to an increased frequency of delayed bleeding. Surprisingly, Tgm2 -/- /F13a1 -/- double knockout mice showed a trend toward decreased dilatation of the aorta 6 weeks after injury, and this finding was replicated in Tgm2 -/- /F13a1 -/- mice subjected to carotid artery injury. Levels of transcripts encoding TG2 were not increased in the aortas of injured wild-type or F13a1 -/- knockout mice relative to uninjured mice, although changes in the levels of other transcripts accorded with previous descriptions of the CaCl2 aneurysm model in mice. CONCLUSIONS: Knockout of Tgm2, but not F13a1 exacerbates aortic dilatation, suggesting that TG2 confers protection. However, levels of TG2 messenger RNA are not acutely elevated after injury. FXIII-A plays a role in preventing postoperative damage after laparotomy, confirming previous reports that it prevents distal organ damage after trauma. TG2 promotes wound healing after surgery and, in its absence, the bleeding diathesis associated with FXIII-A deficiency is further exposed.
RESUMO
Endothelial insulin receptors (Insr) promote sprouting angiogenesis, although the underpinning cellular and molecular mechanisms are unknown. Comparing mice with whole-body insulin receptor haploinsufficiency (Insr+/-) against littermate controls, we found impaired limb perfusion and muscle capillary density after inducing hind-limb ischemia; this was in spite of increased expression of the proangiogenic growth factor Vegfa. Insr+/- neonatal retinas exhibited reduced tip cell number and branching complexity during developmental angiogenesis, which was also found in separate studies of mice with endothelium-restricted Insr haploinsufficiency. Functional responses to vascular endothelial growth factor A (VEGF-A), including in vitro angiogenesis, were also impaired in aortic rings and pulmonary endothelial cells from Insr+/- mice. Human umbilical vein endothelial cells with shRNA-mediated knockdown of Insr also demonstrated impaired functional angiogenic responses to VEGF-A. VEGF-A signaling to Akt and endothelial nitric oxide synthase was intact, but downstream signaling to extracellular signal-reduced kinase 1/2 (ERK1/2) was impaired, as was VEGF receptor-2 (VEGFR-2) internalization, which is required specifically for signaling to ERK1/2. Hence, endothelial insulin receptors facilitate the functional response to VEGF-A during angiogenic sprouting and are required for appropriate signal transduction from VEGFR-2 to ERK1/2.
Assuntos
Endotélio Vascular/metabolismo , Sistema de Sinalização das MAP Quinases , Neovascularização Fisiológica , Receptor de Insulina/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Animais , Células Endoteliais da Veia Umbilical Humana , Humanos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neovascularização Patológica , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
Pericytes regulate vascular development, stability, and quiescence; their dysfunction contributes to diabetic retinopathy. To explore the role of insulin receptors in pericyte biology, we created pericyte insulin receptor knockout mice (PIRKO) by crossing PDGFRß-Cre mice with insulin receptor (Insr) floxed mice. Their neonatal retinal vasculature exhibited perivenous hypervascularity with venular dilatation, plus increased angiogenic sprouting in superficial and deep layers. Pericyte coverage of capillaries was unaltered in perivenous and periarterial plexi, and no differences in vascular regression or endothelial proliferation were apparent. Isolated brain pericytes from PIRKO had decreased angiopoietin-1 mRNA, whereas retinal and lung angiopoietin-2 mRNA was increased. Endothelial phospho-Tie2 staining was diminished and FoxO1 was more frequently nuclear localized in the perivenous plexus of PIRKO, in keeping with reduced angiopoietin-Tie2 signaling. Silencing of Insr in human brain pericytes led to reduced insulin-stimulated angiopoietin-1 secretion, and conditioned media from these cells was less able to induce Tie2 phosphorylation in human endothelial cells. Hence, insulin signaling in pericytes promotes angiopoietin-1 secretion and endothelial Tie2 signaling and perturbation of this leads to excessive vascular sprouting and venous plexus abnormalities. This phenotype mimics elements of diabetic retinopathy, and future work should evaluate pericyte insulin signaling in this disease.
Assuntos
Angiopoietina-2/genética , Células Endoteliais/metabolismo , Pericitos/metabolismo , Receptor de Insulina/fisiologia , Remodelação Vascular/genética , Angiopoietina-2/metabolismo , Angiopoietinas/genética , Angiopoietinas/metabolismo , Animais , Células Cultivadas , Células Endoteliais/efeitos dos fármacos , Insulina/metabolismo , Insulina/farmacologia , Camundongos , Camundongos Knockout , Pericitos/efeitos dos fármacos , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Retina/efeitos dos fármacos , Retina/metabolismo , Vasos Retinianos/efeitos dos fármacos , Vasos Retinianos/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Remodelação Vascular/efeitos dos fármacosRESUMO
We have previously reported that overexpression of human insulin-like growth factor binding protein (IGFBP)-1 in mice leads to vascular insulin sensitization, increased nitric oxide bioavailability, reduced atherosclerosis, and enhanced vascular repair, and in the setting of obesity improves glucose tolerance. Human studies suggest that low levels of IGFBP-1 are permissive for the development of diabetes and cardiovascular disease. Here we seek to determine whether loss of IGFBP-1 plays a causal role in the predisposition to cardiometabolic disease. Metabolic phenotyping was performed in transgenic mice with homozygous knockout of IGFBP-1. This included glucose, insulin, and insulin-like growth factor I tolerance testing under normal diet and high-fat feeding conditions. Vascular phenotyping was then performed in the same mice using vasomotor aortic ring studies, flow cytometry, vascular wire injury, and angiogenesis assays. These were complemented with vascular phenotyping of IGFBP-1 overexpressing mice. Metabolic phenotype was similar in IGFBP-1 knockout and wild-type mice subjected to obesity. Deletion of IGFBP-1 inhibited endothelial regeneration following injury, suggesting that IGFBP-1 is required for effective vascular repair. Developmental angiogenesis was unaltered by deletion or overexpression of IGFBP-1. Recovery of perfusion following hind limb ischemia was unchanged in mice lacking or overexpressing IGFBP-1; however, overexpression of IGFBP-1 stimulated hindlimb perfusion and angiogenesis in insulin-resistant mice. These findings provide new insights into the role of IGFBP-1 in metabolic and vascular pathophysiology. Irrespective of whether loss of IGFBP-1 plays a causal role in the development of cardiometabolic disorders, increasing IGFBP-1 levels appears effective in promoting neovascularization in response to ischemia.
RESUMO
Diabetes, obesity, and Alzheimer's disease (AD) are associated with vascular complications and impaired nitric oxide (NO) production. Furthermore, increased ß-site amyloid precursor protein-cleaving (APP-cleaving) enzyme 1 (BACE1), APP, and ß-amyloid (Aß) are linked with vascular disease development and increased BACE1 and Aß accompany hyperglycemia and hyperlipidemia. However, the causal relationship between obesity and diabetes, increased Aß, and vascular dysfunction is unclear. We report that diet-induced obesity (DIO) in mice increased plasma and vascular Aß42 that correlated with decreased NO bioavailability, endothelial dysfunction, and increased blood pressure. Genetic or pharmacological reduction of BACE1 activity and Aß42 prevented and reversed, respectively, these outcomes. In contrast, expression of human mutant APP in mice or Aß42 infusion into control diet-fed mice to mimic obese levels impaired NO production, vascular relaxation, and raised blood pressure. In humans, increased plasma Aß42 correlated with diabetes and endothelial dysfunction. Mechanistically, higher Aß42 reduced endothelial NO synthase (eNOS), cyclic GMP (cGMP), and protein kinase G (PKG) activity independently of diet, whereas endothelin-1 was increased by diet and Aß42. Lowering Aß42 reversed the DIO deficit in the eNOS/cGMP/PKG pathway and decreased endothelin-1. Our findings suggest that BACE1 inhibitors may have therapeutic value in the treatment of vascular disease associated with diabetes.
Assuntos
Peptídeos beta-Amiloides/sangue , Diabetes Mellitus/sangue , Angiopatias Diabéticas/sangue , Obesidade/sangue , Fragmentos de Peptídeos/sangue , Transdução de Sinais , Peptídeos beta-Amiloides/genética , Animais , Proteínas Quinases Dependentes de GMP Cíclico/genética , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Diabetes Mellitus/genética , Diabetes Mellitus/patologia , Angiopatias Diabéticas/genética , Angiopatias Diabéticas/patologia , Feminino , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Óxido Nítrico/sangue , Óxido Nítrico/genética , Óxido Nítrico Sintase Tipo III/genética , Óxido Nítrico Sintase Tipo III/metabolismo , Obesidade/genética , Obesidade/patologia , Fragmentos de Peptídeos/genéticaRESUMO
BACKGROUND: Enhanced sympathetic activation has a central role in the development of heart failure (HF). We assessed whether the alpha(2C)-adrenoceptor (Del322-325) polymorphism exclusively or in combination with a beta(1)-adrenoceptor (Arg389) polymorphism, each with known independent effects on sympathetic function, were associated with an increased risk of adverse events in HF. METHODS AND RESULTS: A total of 526 patients enrolled in the Metoprolol CR/XL Randomized Intervention Trial in Congestive Heart Failure study were genotyped for both adrenoceptor polymorphisms. The distribution of alpha(2C) genotypes was similar between the event and nonevent groups. However, a reduced prevalence of the Del322-325 allele was found in individuals with ischemic congestive HF (P=.022). Patients possessing both the alpha(2C) Del322-325 and beta(1) Arg389 alleles had no increased risk of events. Adjusting for confounding variables and the beta(1) Arg389Gly polymorphism, the odds ratio of being ins/del + del/del for the alpha(2C) Del322-325 and having an event was 0.89 with 95% CI 0.49-1.63, P=.715. Similarly, adjusting for confounding variables and the alpha(2C) Del322-325 polymorphism the odds ratio of being Arg/Arg or Arg/Gly for the beta(1) Arg389Gly polymorphism and having an event was 1.13 with 95% CI 0.52-2.17, P=.864. CONCLUSIONS: The alpha(2C) Del322-325 polymorphism exclusively or in combination with the beta(1)Arg389 allele is not associated with an increased risk of adverse events in HF.
Assuntos
DNA/genética , Insuficiência Cardíaca/genética , Polimorfismo Genético , Receptores Adrenérgicos alfa 2/genética , Receptores Adrenérgicos beta 1/genética , Idoso , Alelos , Feminino , Genótipo , Insuficiência Cardíaca/sangue , Humanos , Masculino , Receptores Adrenérgicos alfa 2/sangue , Receptores Adrenérgicos beta 1/sangue , Fatores de Risco , Análise de Sequência de DNA , Índice de Gravidade de DoençaRESUMO
Transient Receptor Potential Canonical 5 (TRPC5) is a subunit of a Ca2+-permeable non-selective cationic channel which negatively regulates adiponectin but not leptin in mice fed chow diet. Adiponectin is a major anti-inflammatory mediator and so we hypothesized an effect of TRPC5 on the inflammatory condition of atherosclerosis. Atherosclerosis was studied in aorta of ApoE-/- mice fed western-style diet. Inhibition of TRPC5 ion permeation was achieved by conditional transgenic expression of a dominant negative ion pore mutant of TRPC5 (DNT5). Gene expression analysis in adipose tissue suggested that DNT5 increases transcript expression for adiponectin while decreasing transcript expression of the inflammatory mediator Tnfα and potentially decreasing Il6, Il1ß and Ccl2. Despite these differences there was mild or no reduction in plaque coverage in the aorta. Unexpectedly DNT5 caused highly significant reduction in body weight gain and reduced adipocyte size after 6 and 12 weeks of western-style diet. Steatosis and circulating lipids were unaffected but mild effects on regulators of lipogenesis could not be excluded, as indicated by small reductions in the expression of Srebp1c, Acaca, Scd1. The data suggest that TRPC5 ion channel permeation has little or no effect on atherosclerosis or steatosis but an unexpected major effect on weight gain.