O tecido adiposo perivascular (PVAT) libera substâncias dilatadoras e constritoras, sendo que as dilatadoras se sobrepõem, exercendo efeito anticontrátil. Esse efeito está prejudicado na presença de algumas doenças cardiovasculares. Na insuficiência cardíaca (IC) ocorrem danos ao sistema vascular, todavia nenhum estudo avaliou a função do PVAT na IC. A utilização do treinamento físico (TF) tem sido recomendada com terapia não farmacológica eficiente em promover benefícios ao sistema cardiovascular. As recomendações sugerem que o exercício resistido seja adicionado aos programas de TF para pacientes com IC, podendo, assim, o treinamento combinado (TC; aeróbio e resistido) fornecer benefícios adicionais à saúde cardiovascular. Com isso, o objetivo do presente trabalho foi avaliar o papel do PVAT na reatividade vascular da aorta torácica dos ratos com IC e, após, avaliar a influência do TC na resposta anticontrátil do PVAT da aorta torácica e abdominal de ratos saudáveis e com IC. Ratos Wistar foram submetidos à oclusão da artéria coronária descendente ou falso operado (SO). Após 4 semanas, para o estudo sem TC os animais foram mantidos sem intervenção, e para o estudo que envolvia o TC foram divididos em sedentários (SOs e ICs) e treinados (SOt e ICt, esteira e escada, 5 x/sem., 8 sem.). Anéis da aorta torácica e/ou abdominal com (E+) e sem endotélio (E-), na presença (PVAT+) ou na ausência do PVAT (PVAT-), foram montados em miógrafo de arame e curvas concentração-resposta à fenilefrina (FEN, 10-910-5M) foram realizadas. A IC promoveu aumento da contração FEN nos anéis E+/PVAT- da aorta torácica quando comparado aos SO, e o efeito anticontrátil do PVAT foi prejudicado pela IC nos anéis E+/PVAT+ e E-/PVAT+. O prejuízo no efeito anticontrátil do PVAT foi acompanhado por maior atividade da ECA1 e da expressão dos AT1R, AT2R e MASR no PVAT dos animais com IC. O antagonismo dos AT1R, AT2R e MASR promoveram redução da resposta contrátil nos anéis E+/PVAT- nos IC, nos anéis E+/PVAT+ essa redução foi superior apenas para o antagonismo do AT1R e AT2R. A produção de espécies reativas de oxigênio (ERO) na aorta torácica e PVAT dos animais IC foi maior que nos SO, acompanhada por uma menor biodisponibilidade de NO. O TC aumentou a capacidade física nos SOt e ICt. Na aorta torácica o TC reverteu parte do prejuízo da função anticontrátil do PVAT, aumentou a expressão do PRDM-16 e ESPST-1 que estavam reduzidos na IC, além disso, melhorou a biodisponibilidade de NO no PVAT pela maior expressão da eNOS, β3-AR e AMPk1/2α, aumentou a concentração de adiponectina e reduziu marcadores pró-inflamatórios. Na aorta abdominal, o efeito anticontrátil do PVAT não estava presente e o TC reverteu a disfunção endotelial dos animais com IC, aumentando a biodisponibilidade de NO e a expressão da eNOS na aorta. Em conclusão, na IC os AT1R e AT2R contribuem tanto para a disfunção endotelial quanto do PVAT, reduzindo a biodisponibilidade de NO e aumentando a produção de ERO. O TC melhorou a função anticontrátil na aorta torácica, por benefícios na via de sinalização α3-AR/Adiponectina/AMPK/eNOS, modificando o perfil morfológico e inflamatório do PVAT. Já na aorta abdominal, o TC melhorou a função vascular, aumentando a biodisponibilidade de NO. / Perivascular adipose tissue (PVAT) releases dilating and constricting substances, and the dilators overlap, exerting an anti-contractile effect. This effect is impaired in the presence of some cardiovascular diseases. In heart failure (HF) damage to the vascular system occurs, however, no study has evaluated the function of PVAT in HF. The use of physical training (PT) has been recommended with non-pharmacological therapy effective in promoting cardiovascular system benefits. The recommendations suggest that resistance exercise be added to the PT programs for patients with HF, thus, combined training (CT, aerobic and resisted) may provide additional cardiovascular health benefits. The objective of the present study was to evaluate the role of PVAT in the vascular reactivity of the thoracic aorta of HF rats and, after that, to evaluate the influence of CT in the anti-contractile response of PVAT of the thoracic and abdominal aorta of healthy and HF rats. Wistar rats were submitted to descending coronary artery occlusion or false operated (SO). After 4 weeks, for the study without CT, the animals were kept without intervention, and for the study involving the CT were divided into sedentary (SOs and HFs) and trained (SOt and HFt, treadmill and ladder, 5 x/8 sem.). In the presence (PVAT+) or in the absence of the PVAT (PVAT-), thoracic and/or abdominal aorta with (E+) and without endothelium (E-), were mounted on wire myograph and concentration-response curves to phenylephrine, (PHE, 10-9-10-5M) were performed. HF promoted an increase in PHE contraction in the E+/PVAT- rings of the thoracic aorta when compared to SO, and the ani-contratile effect of PVAT was impaired by HF in the E+/PVAT+ and E-/PVAT+ rings. The impairment in the anti-contratile effect of PVAT was accompanied by increased activity of ECA1 and the expression of AT1R, AT2R and MASR in the PVAT of animals with HF. The AT1R, AT2R and MASR antagonism promoted a reduction of the contractile response in the E+/PVAT- rings in the HF, in the E+/PVAT+ rings, this reduction was superior only to the antagonism of AT1R and AT2R. The production of reactive oxygen species (ROS) in the thoracic aorta and PVAT of the HF animals was higher than in the SO, accompanied by a lower NO bioavailability. CT increased physical capacity in SOt and HFt. In the thoracic aorta CT reversed part of the impairment of PVAT anti-contratile function, increased the expression of PRDM-16 and ESPST-1 that were reduced in HF, in addition, it improved the bioavailability of NO in PVAT by the greater expression of eNOS, β3-AR and AMPk1/2 α, increased the concentration of adiponectin and reduced proinflammatory markers. In the abdominal aorta, the anti-contratile effect of PVAT was not present and CT reversed the endothelial dysfunction of HF animals, increasing NO bioavailability and eNOS expression in the aorta. In conclusion, in HF, AT1R and AT2R contribute to both endothelial and PVAT dysfunction, reducing NO bioavailability and increasing ROS production. CT improved the anti-contractile function in the thoracic aorta due to benefits in the β3-AR/Adiponectin/AMPK/eNOS signaling pathway, modifying the morphological and inflammatory profile of PVAT. Already in the abdominal aorta, the CT improved the vascular function, the CT improved the vascular function, increasing the bioavailability of NO.

A obesidade desencadeia mudanças funcionais no tecido adiposo perivascular (PVAT), favorecendo a liberação de fatores vasoconstritores e consequente ativação de mecanismos contráteis em células vasculares. A sinalização da interleucina 33 (IL-33) via receptor ST2 é essencial para o desenvolvimento e manutenção de células T reguladoras (Tregs) no tecido adiposo visceral. Na obesidade a função das Tregs é comprometida, resultando em estresse oxidativo e inflamação do tecido adiposo. No presente estudo testamos a hipótese que dieta rica em gordura diminui os níveis e a função da IL-33 no PVAT, levando à diminuição do número e função de Tregs, estresse oxidativo e inflamação neste tecido. Camundongos deficientes para o receptor ST2 (ST2 KO) e seus respectivos controles (Balb/C) receberam dieta controle ou hiperlipídica (HFD, high fat diet) durante 18 semanas. A função vascular foi avaliada em anéis de artérias mesentéricas, em presença ou ausência de PVAT, realizando-se curvas concentração-efeito para fenilefrina. Os seguintes grupos experimentais foram analisados: Controle PVAT (-), Controle PVAT (+), HFD PVAT (-) e HFD PVAT (+). Em artérias de camundongos Balb/C que receberam dieta controle, o PVAT diminuiu a resposta contrátil a fenilefrina. No entanto, HFD promoveu perda parcial do efeito anticontrátil promovido por este tecido. Em camundongos ST2 KO que receberam dieta controle, o PVAT diminuiu a resposta contrátil a fenilefrina. No entanto, a ausência de receptores ST2 em camundongos que receberam HFD levou à perda completa do efeito anticontrátil do PVAT. Houve diminuição do número de Tregs e aumento do número de neutrófilos no PVAT de camundongos alimentados com HFD. A incubação com IL-33 recombinante não reverteu a perda do efeito anticontrátil do PVAT promovido pela HFD. Aumento nos níveis séricos e teciduais de IL-6, bem como redução nos níveis de IL-10, foram observados em animais ST2 KO. Houve aumento nos níveis de ânion superóxido no PVAT de camundongos Balb/C alimentados com HFD e a ausência do receptor ST2 potencializou este efeito. Estes dados, analisados em conjunto, indicam que HFD compromete o papel modulador do PVAT e que IL-33 via receptor ST2 tem fundamental importância para a função do PVAT nesta condição experimental. / Obesity triggers functional changes in the perivascular adipose tissue (PVAT), favoring the release of vasoconstrictor factors. Interleukin-33 (IL-33) signaling, via ST2 receptor, is essential for the development and maintenance of regulatory T cells (Tregs) in the visceral adipose tissue. In obesity, Tregs function is compromised, resulting in adipose tissue inflammation. We hypothesized that high fat diet (HFD) decreases the number and function of Tregs and increases inflammation in the PVAT. Mice deficient for the ST2 receptor (ST2 KO) and their respective controls (Balb/C mice) were fed a control diet or a HFD for 18 weeks. Vascular function was evaluated in mesenteric resistance arteries, by performing concentration-effect curves to phenylephrine (PE). In Balb/C mice fed the control diet, PVAT decreased vascular PE contractions. However, a partial loss of PVAT anticontractile effect occurred in arteries from HFD-fed Balb/C mice. In arteries from ST2 KO mice fed the control diet, PVAT decreased PE contractions. However, a complete loss of PVAT anticontractile effects was observed in HFD-fed ST2 KO mice. There was a decrease in the number of Tregs and an increase in the number of neutrophils in the PVAT of mice fed the HFD. The absence of the IL-33 receptor increased IL-6 and reduced IL-10 in HFD-fed mice. There was an increase in superoxide anion levels in the PVAT of Balb/C mice fed HFD and the absence of the ST2 receptor potentiated this effect. These data show that HFD promotes PVAT dysfunction and IL-33 is fundamental to counteract HFD-induced PVAT dysfunction.

Ο λιπώδης ιστός θεωρείται πλέον ενδοκρινές όργανο που παράγει πληθώρα βιολογικά δραστικών πεπτιδίων, που καλούνται λιποκίνες. Ανάλογα με την ανατομική τους εντόπιση, οι διαφορετικές αποθήκες λίπους έχουν και διαφορετική ικανότητα παραγωγής λιποκινών και επίδρασης σε φυσιολογικές λειτουργίες. Οι λιποκίνες που παράγονται από τον περιαγγειακό λιπώδη ιστό εμπλέκονται στην παθογένεια αγγειακών νόσων, συμπεριλαμβανόμενης της αθηροσκλήρωσης. Είναι γνωστό πως η αντιπονεκτίνη ασκεί αντιαθηρογόνες δράσεις, ενώ ο ρόλος της Τ-καντχερίνης ως υποδοχέα της αντιπονεκτίνης δεν έχει πλήρως διαλευκανθεί. Το απελινεργικό σύστημα, αποτελούμενο από την απελίνη και τον υποδοχέα της APJ, αποτελεί μεσολαβητή ποικίλων καρδιαγγειακών λειτουργιών και ενδέχεται να συμμετέχει και στην αθηροσκληρωτική διαδικασία. Η χεμερίνη είναι λιποκίνη με γνωστό ρόλο στην ανοσία, στη λειτουργία του λιπώδους ιστού και στο μεταβολισμό, δρώντας κυρίως μέσω του υποδοχέα της CMKLR1. Μελετήσαμε την πρωτεϊνική έκφραση της αντιπονεκτίνης και της Τ-καντχερίνης, της απελίνης και του APJ, της χεμερίνης και του CMKLR1 σε ανθρώπινες αορτές, στεφανιαίες αρτηρίες και στον αντίστοιχο περιαγγειακό λιπώδη ιστό και συσχετίσαμε την έκφρασή τους με την παρουσία αθηροσκλήρωσης και με κλινικές παραμέτρους. Εφαρμόστηκε ανοσοϊστοχημική χρώση για την αντιπονεκτίνη, την Τ-καντχερίνη, την απελίνη, τον APJ, τη χεμερίνη και τον CMKLR1 σε δείγματα ανθρώπινων αορτών και στεφανιαίων αρτηριών, περιλαμβανόμενου και του περιαγγειακού λίπους. Οι αορτικές και στεφανιαίες αθηρωματικές βλάβες αξιολογήθηκαν με βάση την κατάταξη του AHA. Ανοσοϊστοχημική χρώση, ποικίλης έντασης, για την αντιπονεκτίνη ανιχνεύθηκε μόνο στα λιποκύτταρα, ενώ η Τ-καντχερίνη εντοπίστηκε στα αγγειακά λεία μυικά κύτταρα (ΑΛΜΚ) και στα ενδοθηλιακά κύτταρα. Ανοσοϊστοχημική χρώση για την απελίνη ανιχνεύθηκε σε λιποκύτταρα, ΑΛΜΚ, ενδοθηλιακά κύτταρα και μακροφάγα-αφρώδη κύτταρα των αθηρωματικών βλαβών, ενώ ο APJ εντοπίστηκε στα ΑΛΜΚ και στο ενδοθήλιο των αγγείων. Ανοσοθετικότητα για τη χεμερίνη παρατηρήθηκε και στις δύο αποθήκες λίπους ,στα ΑΛΜΚ και σε αφρώδη κύτταρα των αθηρωματικών βλαβών. Ο CMKLR1 εκφράστηκε σε ΑΛΜΚ και σε αφρώδη κύτταρα αορτών και στεφανιαίων αγγείων με αθηρωματικές βλάβες. Η έκφραση αντιπονεκτίνης στον περιαγγειακό λιπώδη ιστό και η έκφραση Τ-καντχερίνης στα ΑΛΜΚ συσχετίστηκαν αρνητικά με την αθηροσκλήρωση και στις δύο εντοπίσεις, όπως και η έκφραση απελίνης στα ΑΛΜΚ. Η έκφραση χεμερίνης στις περιαγγειακές αποθήκες λίπους και στα αφρώδη κύτταρα συσχετίστηκε στατιστικά σημαντικά με τη βαρύτητα της αθηροσκλήρωσης και στις δύο εντοπίσεις. Πολλές ακόμα – ειδικές για την εντόπιση – συσχετίσεις παρατηρήθηκαν. Τα αποτελέσματά μας υποδεικνύουν πιθανό ρόλο της Τ-καντχερίνης ως μεσολαβητή των αντιαθηρογόνων δράσεων της αντιπονεκτίνης, ενώ υποστηρίζουν το ενδεχόμενο αντιαθηρογόνο προφίλ της απελίνης και του υποδοχέα της APJ στις ανθρώπινες αρτηρίες. Ενισχύουν, ακόμα, τον υποτιθέμενο ρόλο της χεμερίνης στην εξέλιξη των αθηρωματικών βλαβών, πιθανότατα δρώντας μέσω του CMKLR1 υποδοχέα της. Περαιτέρω έρευνα είναι αναγκαία για να αποσαφηνιστεί ο ρόλος της τοπικά παραγόμενης αντιπονεκτίνης, απελίνης και χεμερίνης και της σηματοδότησης μέσω των αντίστοιχων υποδοχέων τους – T-cadherin, APJ και CMKLR1 – στην παθογένεια της αθηροσκλήρωσης στον άνθρωπο. / Adipose tissue is considered an endocrine organ, producing numerous bioactive peptides, called adipokines. Depending on their anatomical location, different fat depots have a different capacity to produce adipokines and influence physiological functions. Adipokines produced by periadventitial fat have been implicated in the pathogenesis of vascular disease, including atherosclerosis. Adiponectin has established anti-atherogenic actions, while the role of T-cadherin as an adiponectin receptor is not fully elucidated. The apelinergic system, consisting of apelin and its APJ receptor, is a mediator of various cardiovascular functions and may also be involved in the atherosclerotic process. Chemerin is an adipokine with an established role in immunity, adipose tissue function and metabolism, acting, mainly through its CMKLR1 receptor. We investigated the protein expression of adiponectin and T-cadherin, apelin and APJ, chemerin and CMKLR1 in human aortas, coronary vessels and the respective periadventitial adipose tissue and correlated their expression with the presence of atherosclerosis and clinical parameters. Immunohistochemistry for adiponectin, T-cadherin, apelin, APJ, chemerin and CMKLR1 was performed on human aortic and coronary artery samples including the periadventitial adipose tissue. Aortic and coronary atherosclerotic lesions were assessed using the AHA classification. Adiponectin immunostaining, of varied intensity, was detected only in adipocytes, while T-cadherin was localized to vascular smooth muscle cells (VSMCs) and endothelial cells. Apelin immunostaining was detected in adipocytes, VSMCs, endothelial cells and foam cells in atherosclerotic lesions, while APJ was found in VSMCs and endothelia. Chemerin immunopositivity was noticed in both periadventitial fat depots, in VSMCs and foam cells in atherosclerotic lesions. CMKLR1 was expressed in VSMCs and foam cells in aortic and coronary vessels with atherosclerotic lesions. Periadventitial adiponectin and VSMC T-cadherin expression were negatively correlated with atherosclerosis in both sites, as was VSMC apelin expression. Chemerin expression in periadventitial fat depots and foam cells was statistically significantly correlated with the severity of atherosclerosis in both locations. Several other – depot specific – associations were observed. Our results suggest a possible role for T-cadherin as a mediator of anti-atherogenic adiponectin actions, while they support the putative anti-atherogenic profile for apelin and its APJ receptor in human arteries. They also lend some support to a presumable role of chemerin in the progression of atherosclerotic lesions, possibly acting through its CMKLR1 receptor. Further research is necessary to elucidate the role of locally produced adiponectin, apelin and chemerin and signaling through their respective receptors – T-cadherin, APJ and CMKLR1 – in the pathogenesis of human atherosclerosis.

A obesidade desencadeia mudanças funcionais no tecido adiposo perivascular (PVAT), favorecendo a liberação de fatores vasoconstritores e consequente ativação de mecanismos contráteis em células vasculares. A sinalização da interleucina 33 (IL-33) via receptor ST2 é essencial para o desenvolvimento e manutenção de células T reguladoras (Tregs) no tecido adiposo visceral. Na obesidade a função das Tregs é comprometida, resultando em estresse oxidativo e inflamação do tecido adiposo. No presente estudo testamos a hipótese que dieta rica em gordura diminui os níveis e a função da IL-33 no PVAT, levando à diminuição do número e função de Tregs, estresse oxidativo e inflamação neste tecido. Camundongos deficientes para o receptor ST2 (ST2 KO) e seus respectivos controles (Balb/C) receberam dieta controle ou hiperlipídica (HFD, high fat diet) durante 18 semanas. A função vascular foi avaliada em anéis de artérias mesentéricas, em presença ou ausência de PVAT, realizando-se curvas concentração-efeito para fenilefrina. Os seguintes grupos experimentais foram analisados: Controle PVAT (-), Controle PVAT (+), HFD PVAT (-) e HFD PVAT (+). Em artérias de camundongos Balb/C que receberam dieta controle, o PVAT diminuiu a resposta contrátil a fenilefrina. No entanto, HFD promoveu perda parcial do efeito anticontrátil promovido por este tecido. Em camundongos ST2 KO que receberam dieta controle, o PVAT diminuiu a resposta contrátil a fenilefrina. No entanto, a ausência de receptores ST2 em camundongos que receberam HFD levou à perda completa do efeito anticontrátil do PVAT. Houve diminuição do número de Tregs e aumento do número de neutrófilos no PVAT de camundongos alimentados com HFD. A incubação com IL-33 recombinante não reverteu a perda do efeito anticontrátil do PVAT promovido pela HFD. Aumento nos níveis séricos e teciduais de IL-6, bem como redução nos níveis de IL-10, foram observados em animais ST2 KO. Houve aumento nos níveis de ânion superóxido no PVAT de camundongos Balb/C alimentados com HFD e a ausência do receptor ST2 potencializou este efeito. Estes dados, analisados em conjunto, indicam que HFD compromete o papel modulador do PVAT e que IL-33 via receptor ST2 tem fundamental importância para a função do PVAT nesta condição experimental. / Obesity triggers functional changes in the perivascular adipose tissue (PVAT), favoring the release of vasoconstrictor factors. Interleukin-33 (IL-33) signaling, via ST2 receptor, is essential for the development and maintenance of regulatory T cells (Tregs) in the visceral adipose tissue. In obesity, Tregs function is compromised, resulting in adipose tissue inflammation. We hypothesized that high fat diet (HFD) decreases the number and function of Tregs and increases inflammation in the PVAT. Mice deficient for the ST2 receptor (ST2 KO) and their respective controls (Balb/C mice) were fed a control diet or a HFD for 18 weeks. Vascular function was evaluated in mesenteric resistance arteries, by performing concentration-effect curves to phenylephrine (PE). In Balb/C mice fed the control diet, PVAT decreased vascular PE contractions. However, a partial loss of PVAT anticontractile effect occurred in arteries from HFD-fed Balb/C mice. In arteries from ST2 KO mice fed the control diet, PVAT decreased PE contractions. However, a complete loss of PVAT anticontractile effects was observed in HFD-fed ST2 KO mice. There was a decrease in the number of Tregs and an increase in the number of neutrophils in the PVAT of mice fed the HFD. The absence of the IL-33 receptor increased IL-6 and reduced IL-10 in HFD-fed mice. There was an increase in superoxide anion levels in the PVAT of Balb/C mice fed HFD and the absence of the ST2 receptor potentiated this effect. These data show that HFD promotes PVAT dysfunction and IL-33 is fundamental to counteract HFD-induced PVAT dysfunction.

Les troubles métaboliques caractéristiques d’une alimentation de type « Western diet », sont à l’origine de pathologies cardiovasculaires, première cause de mortalité dans le monde. Il apparait nécessaire d’améliorer la compréhension des mécanismes impliqués dans l’installation des dysfonctions cardiovasculaires afin de pouvoir proposer des stratégies thérapeutiques ou préventives adaptées. Ainsi, le premier objectif de la thèse a été d’évaluer les effets d’une boisson sucrée sur la fonction vasculaire macro- et micro-circulatoire chez des sujets sains, par une approche translationnelle allant de la clinique humaine à un modèle expérimental de rongeur. Nos résultats montrent une altération de la fonction endothéliale en réponse à une prise de boisson sucrée, dans l’ensemble des lits vasculaires. L’exploration des mécanismes sous-jacents ces altérations nous a permis d’identifier l’implication du couple stress-oxydant/voie du NO. Un second objectif de thèse, a été d’étudier l’impact d’un stress métabolique chronique sur la fonction vasculaire et son incidence sur la régulation de la pression artérielle. Comme observé chez certains sujets souffrant de syndrome métabolique, notre modèle de rat ne présentait pas d’hypertension artérielle, malgré une hyperactivité du système sympathique. Ceci semble être expliqué par une compensation endothéliale eNOS-dépendant, qui permet de garantir le maintien d’une pression artérielle normale en dépit de l’effet vasopresseur adrénergique élevé. Le troisième objectif de thèse a porté sur un nouvel élément participant au maintien de l’homéostasie vasculaire et impacté par les situations pathologiques : le tissu adipeux périvasculaire (PVAT). Nos travaux démontrent dans le contexte du SMet, une altération de la voie adiponectine/eNOS dans le PVAT, en parallèle d’une augmentation de la production d’espèces oxygénées réactives.La pratique régulière d’un exercice physique est aujourd’hui reconnue comme une stratégie non-pharmacologique permettant d’impacter à la fois les désordres métaboliques et cardiovasculaires, notamment via une amélioration de la voie du NO. Nos résultats démontrent une limitation de l’apparition des dysfonctions endothéliales causée par une hyperglycémie aigue lorsqu’un protocole d’exercice physique chronique est réalisé. Enfin, l’exercice physique permet également de prévenir les modifications des propriétés vaso-actives du PVAT dans un modèle de rat SMet. Ce phénomène pourrait être expliqué par une amélioration du statut oxydant de la paroi artérielle, et à une potentialisation de la voie adiponectine/eNOS par l’exercice physique / The globalization of the western diet has mediated prevalence in cardiovascular disease related mortality, the single leading cause of death worldwide. Considering this, it is imperative that the underlying mechanisms of cardiovascular dysfunctions are continually investigated to establish a greater understanding of its pathogenesis from a healthy state to the presence of cardiometabolic diseases; and to improve upon current treatment and preventative strategies. Therefore, the first aim of this research was to identify vascular impact of acute hyperglycaemic stress induced by sweet sugar beverage consumption, with a translational approach. The results of this study demonstrated that consumption of a single commercially available sugar-sweetened beverage (SSB) induced transient micro- and macrovascular endothelial dysfunction, even in a healthy population. Further exploration into the underlying mechanisms of SSB-mediated endothelial dysfunction indicated that an increase in oxidative stress disrupts normal function of the nitric oxide pathway. Although disturbances in cardiovascular function may initially be transient, repetitive acute metabolic stress may translate to chronic cardiometabolic disease. Therefore, the second aim of this research was to assess the impact of a chronic metabolic disorder, metabolic syndrome (MetS), on vascular function in a rat model. Despite increasing sympathetic activity, the MetS rats didn’t present elevated arterial pressure. Such findings may be explained by a compensatory adaptation of endothelial function that increases production of nitric oxide in response to α-adrenergic agonist and, thus, regulates arterial pressure despite sympathetic hyperactivity. Considering this, the third aim of this research evaluated the impact of perivascular adipose tissue (PVAT) on vascular fucntion in MetS rats; demonstrating that MetS altered the adiponectin-endothelial nitric oxide synthase pathway in PVAT, in an oxidative stress-dependant manner.Exercise training is well recognized as a non-pharmacological strategy that has a beneficial impact on both metabolic and cardiovascular disorders via an improvement in function of the nitric oxide pathway. Considering this, research also assessed the efficacy of this approach to prevent vascular injury induced by acute hyperglycaemia in a healthy population and by PVAT in those with MetS. It was demonstrated that exercise attenuated acute hyperglycemia-mediated endothelial dysfunction; and restored endothelium-dependent vascular reactivity in rats with MetS, due to an improvement in the biocommunication between PVAT and arterial tissue and a notable enhancement of the adiponectine-endothelial nitric oxide synthase pathway.

Indiana University-Purdue University Indianapolis (IUPUI) / The epidemic of obesity and associated cardiovascular complications continues to grow at an alarming rate. Currently, obesity is thought to initiate a state of chronic inflammation, which if unresolved potentially causes cardiovascular dysfunction and disease. Although poorly understood, release of inflammatory mediators and other cytokines from adipose tissue (adipocytokines) has been proposed to be the molecular link between obesity and coronary artery disease. Furthermore, the anatomic location of adipose has been increasingly recognized as a potential contributor to vascular disease. Importantly, the development of coronary atherosclerosis, a key component of heart disease, is typically found in segments of coronary arteries surrounded by perivascular adipose tissue. Accordingly, the goal of this project was to determine how perivascular adipose tissue affects coronary artery function and elucidate the critical mechanisms involved. Initial studies assessing arterial function were conducted with and without perivascular adipose tissue. Preliminary results demonstrated that factors released by perivascular adipose tissue effectively impaired coronary endothelial function both in vitro and in vivo. This observation was determined to be caused by direct inhibition of nitric oxide synthase (NOS), a critical enzyme for the production nitric oxide. Attenuation of endothelium-dependent vasodilation was independent of changes in superoxide production, smooth muscle response, or peroxide-mediated vasodilation. Additional studies revealed that perivascular adipose-induced impairment of NOS was due to increased inhibitory regulation by the β isoform of protein kinase C (PKC-β). Specifically, perivascular adipose-derived factors caused site specific phosphorylation of nitric oxide synthase at Thr-495. Additional experiments investigated how perivascular adipose-derived factors contributed to coronary artery disease in an animal model of obesity. Results from these studies indicated that perivascular adipose-derived leptin markedly exacerbated underlying endothelial dysfunction, and significantly contributed to coronary endothelial dysfunction through a PKC-β dependent mechanism. Findings from this project confirm epicardial perivascular adipose tissue as a local source of harmful adipocytokines. In addition, perivascular adipose-derived leptin was demonstrated to be a critical mediator of coronary vascular dysfunction in obesity. Together, the results strongly suggest that perivascular adipose tissue is a key contributor to coronary artery disease in obesity.