Search

The human pathogen Neisseria meningitidis colonizes blood vessels and causes vascular damage, despite a neutrophil-rich inflammatory infiltrate. Here, Manriquez et al. use a humanized mouse model to show that pathogen colonization of capillaries and arterioles creates an intravascular niche that precludes an effective action of neutrophils.

Although the primary origin of sickle cell disease is a hemoglobin disorder, many types of cells contribute considerably to the pathophysiology of the disease. The adhesion of neutrophils to activated endothelium is critical in the pathophysiology of sickle cell disease and targeting neutrophils and their interactions with endothelium represents an important opportunity for the development of new therapeutics. We focused on endothelin-1, a mediator involved in neutrophil activation and recruitment in tissues, and investigated the involvement of the endothelin receptors in the interaction of neutrophils with endothelial cells. We used fluorescence intravital microscopy analyses of the microcirculation in sickle mice and quantitative microfluidic fluorescence microscopy of human blood. Both experiments on the mouse model and patients indicate that blocking endothelin receptors, particularly ETB receptor, strongly influences neutrophil recruitment under inflammatory conditions in sickle cell disease. We show that human neutrophils have functional ETB receptors with calcium signaling capability, leading to increased adhesion to the endothelium through effects on both endothelial cells and neutrophils. Intact ETB function was found to be required for tumor necrosis factor α-dependent upregulation of CD11b on neutrophils. Furthermore, we confirmed that human neutrophils synthesize endothelin-1, which may be involved in autocrine and paracrine pathophysiological actions. Thus, the endothelin-ETB axis should be considered as a cytokine-like potent pro-inflammatory pathway in sickle cell disease. Blockade of endothelin receptors, including ETB, may provide major benefits for preventing or treating vaso-occlusive crises in sickle cell patients.

Obesity is traditionally linked to diabetes and cardiovascular diseases. Very recent experimental, clinical and epidemiological, sometimes provocative, data challenge this automaticity by showing that not the amount but the distribution of fat is the important determinant. Moderate abdominal fat accumulation may thus be more harmful than even consequent overweight. In view of the worldwide burden of obesity, factors leading to it in children and young adults must urgently be identified. Since obesity is a very complex cardiometabolic situation, this will require to focus investigations on uncomplicated obese subjects and adequate animal models. The recent discovery of intergenerational transmissions of obesity risk factors and also the key role played by gestational and perinatal events (epigenetic factors) give rise to completely new concepts and research avenues. Considering the potential close relationship between microcirculation and tissue metabolism, demonstrations of structural and/or functional abnormalities in microvascular physiology very early in life of subjects at risk for obesity might provide a solid basis for further investigations of such links. Microcirculation(arterioles, capillaries and venules) is conceivably a key compartment determining over one or several decades the translation of genetic and epigenetic factors into fat accumulation. Available animal models should serve to answer this cardinal question.A obesidade é tradicionalmente associada ao diabetes e adoenças cardiovasculares. Dados muito recentes, algumasvezes provocativos, experimentais, clínicos e epidemiológicos questionam essa associação automática mostrando que não é a quantidade, mas a distribuição de gordura que é o determinante importante. O acúmulo moderado de gordura abdominal pode ser mais danoso que o conseqüente sobrepeso. Tendo em vista o aumento mundial da obesidade, fatores que levam a isso em crianças e adultos jovens devem ser urgentemente identificados. Como a obesidade é uma situação cardiometabólica muito complexa, essa identificação deve ser feita em obesos não-complicados e em modelos animais adequados. A recente descoberta da transmissão inter-geração de fatores de risco da obesidade e também do papel fundamental da gestação e de eventos perinatais (fatores epi-genéticos) dão origem a conceitos e linhas de pesquisa completamente novos. Considerando a estreita relação potencial entre a microcirculação e o metabolismo tecidual, demonstrações de anormalidades estruturais e/ou funcionais na fisiologia microvascular muito cedo na vida de pessoas com risco para obesidade podem fornecer uma base sólida para investigações futuras dessas ligações. A microcirculação (arteríolas, capilares e vênulas) é conceitualmente um compartimento chave na determinação em uma ou várias décadas dos fatores genéticos e epi-genéticos em acúmulo de gordura. Os modelos experimentais disponíveis devem servir para responder essa questão extremamente relevante.

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.

Copyright of Recherches en Sciences de Gestion is the property of ISEOR and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Neisseria 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., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Although the primary origin of sickle cell disease is a hemoglobin disorder, many types of cells contribute considerably to the pathophysiology of the disease. The adhesion of neutrophils to activated endothelium is critical in the pathophysiology of sickle cell disease and targeting neutrophils and their interactions with endothelium represents an important opportunity for the development of new therapeutics. We focused on endothelin-1, a mediator involved in neutrophil activation and recruitment in tissues, and investigated the involvement of the endothelin receptors in the interaction of neutrophils with endothelial cells. We used fluorescence intravital microscopy analyses of the microcirculation in sickle mice and quantitative microfluidic fluorescence microscopy of human blood. Both experiments on the mouse model and patients indicate that blocking endothelin receptors, particularly ET B receptor, strongly influences neutrophil recruitment under inflammatory conditions in sickle cell disease. We show that human neutrophils have functional ET B receptors with calcium signaling capability, leading to increased adhesion to the endothelium through effects on both endothelial cells and neutrophils. Intact ET B function was found to be required for tumor necrosis factor α-dependent upregulation of CD11b on neutrophils. Furthermore, we confirmed that human neutrophils synthesize endothelin-1, which may be involved in autocrine and paracrine pathophysiological actions. Thus, the endothelin-ET B axis should be considered as a cytokine-like potent pro-inflammatory pathway in sickle cell disease. Blockade of endothelin receptors, including ET B , may provide major benefits for preventing or treating vaso-occlusive crises in sickle cell patients., (Copyright© 2017 Ferrata Storti Foundation.)

The aims of our study were to investigate effects of postnatal overnutrition, obtained by restricting the number of pups per litter, on microcirculatory reactivity, fat depots, its total percentage and lipid profile. Microvascular reactivity was evaluated in the cremaster muscle of 24 hamsters divided into four groups, with 6 animals in each one: normal (NL) and restricted (RL) litter groups, both at 6th and 21st weeks of age. The NL group had 8-9 pups and the RL 3 pups per litter and to avoid the litter effect, only one animal was used per litter. The results have shown that the RL group had higher velocity of weight, body mass and fat gain compared to the NL one at weeks 6 and 21. Significant differences were also observed on urogenital fat depot, total cholesterol and low density lipoprotein between groups. At the lowest concentration of Ach, the RL group showed smaller arteriolar dilatation at the 21st than at the 6th week [5(3-13) vs 19(8-40)%, p<0.01] while the NL one did not show any difference within the group. The highest concentration of Ach at the 21th week pointed to endothelial-dependent microvascular dysfunction in RL compared to NL [3(8-26) vs. 13(8-26)%, p<0.05]. Endothelial-independent microvascular reactivity was similar between groups. Our data suggest that postnatal overnutrition is associated to muscle endothelial-dependent microvascular dysfunction, greater body mass and total percentage of fat and impaired the lipid profile. In conclusion, the imprinting promoted by this experimental model of obesity was able to influence microvascular reactivity later in life., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Obesity is traditionally linked to diabetes and cardiovascular diseases. Very recent experimental, clinical and epidemiological, sometimes provocative, data challenge this automaticity by showing that not the amount but the distribution of fat is the important determinant. Moderate abdominal fat accumulation may thus be more harmful than even consequent overweight. In view of the worldwide burden of obesity, factors leading to it in children and young adults must urgently be identified. Since obesity is a very complex cardiometabolic situation, this will require to focus investigations on uncomplicated obese subjects and adequate animal models. The recent discovery of intergenerational transmissions of obesity risk factors and also the key role played by gestational and perinatal events (epigenetic factors) give rise to completely new concepts and research avenues. Considering the potential close relationship between microcirculation and tissue metabolism, demonstrations of structural and/or functional abnormalities in microvascular physiology very early in life of subjects at risk for obesity might provide a solid basis for further investigations of such links. Microcirculation(arterioles, capillaries and venules) is conceivably a key compartment determining over one or several decades the translation of genetic and epigenetic factors into fat accumulation. Available animal models should serve to answer this cardinal question.

Cardiovascular diseases continue to be the main cause of death in most industrialized countries. Endothelial dysfunction, a systemic process, is the earliest known marker of atherosclerosis and has become a major focus in acute ischemic disorders. We are investigating the hypothesis that, in these diseases, microvascular and endothelial dysfunctions occur simultaneously and precede the onset of macrovascular disease. We studied, to our knowledge for the first time in the same subjects, microvascular and endothelial functions in 11 patients with type 2 diabetes. 36 metabolic syndrome patients (NCEP-ATPIII criteria) and 25 young obese women matched with healthy controls. Micro vascular morphology and hemodynamics were evaluated non-invasively by means of nailfold videocapillaroscopy. Red blood cell velocity (RBCV, mm/s) was measured at rest and after release from 60 s of arterial occlusion (RBCVmax, mm/s) at the finger base, along with the time to reach RBCVmax (TRBCVmax, s), by video analysis with Cap Image software. Venous occlusion plethysmography was performed after intra-arterial infusions of acetylcholine and sodium nitroprusside to assess endo thelial-dependent and -independent vasodilation, respectively. We found similar results in the three groups of subjects, namely a significant decrease in RBCVmax, an increase in TRBCVmax, and a decrease in endothelial-dependent vasodilation. These findings clearly demonstrate that the two dysfunctions occur simultaneously in these groups of patients. Several mechanisms which could impair micro vascular and endothelial functions are associated with insulin resistance, and drugs that act on insulin resistance might thus be beneficial. Metformin, given to 16 first-degree relatives of patients with type 2 diabetes mellitus, who had the metabolic syndrome and normal glucose tolerance (ADA criteria), improved endothelial-dependent vasodilation and microcirculatory function. Rosiglitazone, given to 18 patients with the metabolic syndrome, enhanced vascular responses by improving endothelial function and increasing adiponectin levels. Increased triglyceride storage is often associated with insulin resistance, contributing to free fatty acid (FFA) overexposure. The two drugs tested here stimulate AMP-activated protein kinase, which promotes FFA oxidation and thus reduces oxidative stress, and might therefore attenuate endothelial lipotoxicity. The results strongly suggest that targeting micro vascular and endothelial dysfunctions in patients with metabolic disorders might help to prevent cardiovascular events, and warrant long-term clinical trials.