Apnéia obstrutiva do sono e resistência à insulina: qual o papel da microcirculação?

Obstructive sleep apnea is an increasingly recognized medical problem. The recent attention to its frequency in the general population and its important role in metabolic, vascular, and behavioral aspects have sharply increased the number and nature of investigations, thereby revealing new aspects that open new approaches in research. Whereas obstructive sleep apnea is a well-known phenomenon accompanying obesity and diabetes, new findings strongly suggest that this close relationship may also operate in the opposite direction. Indeed obstructive sleep apnea may be a primary feature inducing or aggravating a series of vascular and metabolic disturbances closely resembling the metabolic syndrome. This review will discuss established and potential mechanisms responsible for these changes. Obstructive sleep apnea indeed appears to gather all the elements necessary to induce insulin resistance, hypertension, and possibly heart failure. After careful analysis of these modifications and considering how they are intertwined, we propose that microcirculation could represent the common denominator mediating the progression of this pathology, as it is eventually the case in the metabolic syndrome and diabetes domain. This plausible hypothesis is discussed in detail and should be verified by appropriate preclinical and clinical protocols, which are now achievable by using noninvasive techniques in humans.A apnéia obstrutiva do sono é um problema médico cujo reconhecimento tem aumentado. As últimas pesquisas mostrando sua freqüência na população em geral e seu importante papel metabólico, vascular e comportamental aumentou o número e a natureza das investigações revelando, assim, novos aspectos que abrem caminhos para estudos. Embora a apnéia obstrutiva do sono seja um fenômeno bem conhecido acompanhando diabetes e obesidade, novas descobertas sugerem que esta relação causal pode também ser verdadeira no sentido inverso. Na realidade, a apnéia obstrutiva do sono pode ser o marco inicial ou primário que induz ou agrava uma série de distúrbios vasculares e metabólicos que se aproximam da síndrome metabólica. Esta revisão discutirá mecanismos estabelecidos e potenciais responsáveis por estas mudanças. A apnéia obstrutiva do sono parece realmente juntar todos os elementos necessários para induzir resistência à insulina, hipertensão e possivelmente insuficiência cardíaca. Após análise cuidadosa destas modificações, considerando que as mesmas são interligadas, propomos que a microcirculação, como ocorre nos casos de síndrome metabólica e diabetes, poderia representar o denominador comum que mediaria a progressão desta patologia. Esta hipótese é discutida em detalhe e deve ser verificada em estudos pré-clínicos e clínicos apropriados que são atualmente possíveis usando técnicas não-invasivas em humanos

Un nouveau type de matière active explique la formation d’agrégats bactériens et leur impact sur l’infection à méningocoque

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Autophagy protein 5 controls flow-dependent endothelial functions

Dysregulated autophagy is associated with cardiovascular and metabolic diseases, where impaired flow-mediated endothelial cell responses promote cardiovascular risk. The mechanism by which the autophagy machinery regulates endothelial functions is complex. We applied multi-omics approaches and in vitro and in vivo functional assays to decipher the diverse roles of autophagy in endothelial cells. We demonstrate that autophagy regulates VEGF-dependent VEGFR signaling and VEGFR-mediated and flow-mediated eNOS activation. Endothelial ATG5 deficiency in vivo results in selective loss of flow-induced vasodilation in mesenteric arteries and kidneys and increased cerebral and renal vascular resistance in vivo. We found a crucial pathophysiological role for autophagy in endothelial cells in flow-mediated outward arterial remodeling, prevention of neointima formation following wire injury, and recovery after myocardial infarction. Together, these findings unravel a fundamental role of autophagy in endothelial function, linking cell proteostasis to mechanosensing

Effets microcirculatoires des LDL modififées (étude, in vivo, chez la souris)

L'objectif de cette étude était de déterminer, in vivo, les effets des LDL modifiées par une situation diabétique sur l'hémodynamique microcirculatoire. Chez des souris anesthésiées, le muscle spinotrapézien était mis à nu pour visualiser, in situ, les artérioles précapillaires (diamètre < à 20 [mu]m) et les petites artérioles (diamètre compris entre 20 [mu]m et 40 [mu]m) par microscopie intravitale grâce à la technologie d'imagerie spectrale à polarisation orthogonale. Le diamètre des artérioles était mesuré en période basale et après une perfusion intraveineuse de LDL non modifiées ou modifiées in vitro (LDL oxydées, LDL glyquées, LDL glycoxydées) ou in vivo (LDL issues de patients diabétiques de type 1 et de type 2). La perfusion de LDL non modifiées, oxydées in vitro ou glycoxydées in vitro ne provoquait pas ou très peu de modifications du diamètre des artérioles du muscle spinotrapézien. Par contre, la perfusion de LDL glyquées in vitro et de LDL issues de patients diabétiques de type 1 et de type 2 induisait une forte vasoconstriction artériolaire. Ces résultats suggèrent que lors du diabète, les LDL glyquées circulantes pourraient contribuer aux anomalies de réactivité microvasculaire observées chez les diabétiques et ainsi favoriser le développement des complications microvasculairesLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Obstructive sleep apnea and insulin resistance: a role for microcirculation?

Obstructive sleep apnea is an increasingly recognized medical problem. The recent attention to its frequency in the general population and its important role in metabolic, vascular, and behavioral aspects have sharply increased the number and nature of investigations, thereby revealing new aspects that open new approaches in research. Whereas obstructive sleep apnea is a well-known phenomenon accompanying obesity and diabetes, new findings strongly suggest that this close relationship may also operate in the opposite direction. Indeed obstructive sleep apnea may be a primary feature inducing or aggravating a series of vascular and metabolic disturbances closely resembling the metabolic syndrome. This review will discuss established and potential mechanisms responsible for these changes. Obstructive sleep apnea indeed appears to gather all the elements necessary to induce insulin resistance, hypertension, and possibly heart failure. After careful analysis of these modifications and considering how they are intertwined, we propose that microcirculation could represent the common denominator mediating the progression of this pathology, as it is eventually the case in the metabolic syndrome and diabetes domain. This plausible hypothesis is discussed in detail and should be verified by appropriate preclinical and clinical protocols, which are now achievable by using noninvasive techniques in humans

Anti-thrombotic treatment enhances antibiotic efficiency in a humanized model of meningococcemia

Meningococcal infections remain particularly difficult to treat. Despite antibiotic therapy, the state of the patients often rapidly deteriorates. Early clinical studies suggest that meningococci acquire a form of resistance to antibiotic treatments during infections. Taking advantage of a humanized animal model of infection, we confirm that adherent bacteria become highly resistant to antibiotic treatments as early as 3-6 hours post infection, although fully sensitive in vitro . Within this time frame, meningococci adhere to the endothelium via their type IV pili, proliferate and eventually fill the vessel lumen. Using intravital imaging, we show that rapidly upon infection blood flow is dramatically decreased, thus limiting antibiotic access to infected vessels. Concomitantly, fibrin is deposited inside infected vessels in proximity to bacterial aggregates. Pharmacologically impairing thrombin generation by inhibiting Factor X activity not only improves blood flow in infected vessels, but also enhances the efficacy of the antibiotic treatment. Our results indicate that the combined administration of anticoagulants together with antibiotics might represent a therapeutic approach to treat meningococcal sepsis more efficiently

Colonization of dermal arterioles by Neisseria meningitidis provides a safe haven from neutrophils

International audienceAbstract The human pathogen Neisseria meningitidis can cause meningitis and fatal systemic disease. The bacteria colonize blood vessels and rapidly cause vascular damage, despite a neutrophil-rich inflammatory infiltrate. Here, we use a humanized mouse model to show that vascular colonization leads to the recruitment of neutrophils, which partially reduce bacterial burden and vascular damage. This partial effect is due to the ability of bacteria to colonize capillaries, venules and arterioles, as observed in human samples. In venules, potent neutrophil recruitment allows efficient bacterial phagocytosis. In contrast, in infected capillaries and arterioles, adhesion molecules such as E-Selectin are not expressed on the endothelium, and intravascular neutrophil recruitment is minimal. Our results indicate that the colonization of capillaries and arterioles by N. meningitidis creates an intravascular niche that precludes the action of neutrophils, resulting in immune escape and progression of the infection

Intermittent pili-mediated forces fluidize Neisseria meningitidis aggregates promoting vascular colonization

International audienceNeisseria meningitidis, a bacterium responsible for meningitis and septicemia, proliferates and eventually fills the lumen of blood capillaries with multicellular aggregates. The impact of this aggregation process and its specific properties are unknown. We first show that aggregative properties are necessary for efficient infection and study their underlying physical mechanisms. Micropipette aspiration and single-cell tracking unravel unique features of an atypical fluidized phase, with single-cell diffusion exceeding that of isolated cells. A quantitative description of the bacterial pair interactions combined with active matter physics-based modeling show that this behavior relies on type IV pili active dynamics that mediate alternating phases of bacteria fast mutual approach, contact, and release. These peculiar fluid properties proved necessary to adjust to the geometry of capillaries upon bacterial proliferation. Intermittent attractive forces thus generate a fluidized phase that allows for efficient colonization of the blood capillary network during infection