Aims/hypothesis Accumulating evidence suggests that maternal obesity may increase the risk of metabolic disease in the offspring. We investigated the effects of established maternal diet-induced obesity on male and female offspring appetite, glucose homeostasis and body composition in rats. Methods Female Wistar rats were fed either a standard chow (3% fat, 7% sugar [wt/wt]) or a palatable obesogenic diet (11% fat, 43% sugar [wt/wt]) for 8 weeks before mating and throughout pregnancy and lactation. Male and female offspring of control and obese dams were weaned on to standard chow and assessed until 12 months of age. Results At mating, obese dams were heavier than control with associated hyperglycaemia and hyperinsulinaemia. Male and female offspring of obese dams were hyperphagic (p<0.0001) and heavier than control (p<0.0001) until 12 months of age. NEFA were raised at 2 months but not at 12 months. At 3 months, OGTT showed more pronounced alteration of glucose homeostasis in male than in female offspring of obese animals. Euglycaemic-hyperinsulinaemic clamps performed at 8 to 9 months in female and 10 to 11 months in male offspring revealed insulin resistance in male offspring of obese dams (p<0.05 compared with control). Body compositional analysis at 12 months also showed increased fat pad weights in male and female offspring of obese animals. Conclusions/interpretation Diet-induced obesity in female rats leads to a state of insulin resistance in male offspring, associated with development of obesity and increased adiposity. An increase in food intake may play a role.

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.

The present review, to the authors' knowledge, is the first to specifically address the relationships between microcirculation and metabolic syndrome, a cluster of metabolic and cardiovascular modifications highly prevalent in the general population. Its close link to overweight and insulin resistance makes it the main cause of the worldwide burden of type 2 diabetes. However, metabolic syndrome is also observed in many other diseases, particularly, but not exclusively, those where insulin resistance is a main feature. Analysis of the literature reveals that this clinical situation is invariably linked to microvascular disturbances, such as abnormalities in arteriolar reactivity, capillary recruitment, permeability, and hemorheology. A particularly interesting observation is that these defects in small vessel structure and function are seen very early in life or disease. Very importantly, they further suggest that microcirculatory abnormalities may be not only secondary but also causal to the development and/or aggravation of insulin resistance and metabolic syndrome. Mechanisms responsible for these modifications remain largely unknown, but insulin's vascular effects in the microvascular network, detailed in this review, are at least one example of such connections. The existing data point to a clear, at least bidirectional, relationship between microcirculation and metabolic syndrome. Additional studies should determine the level of reciprocal causality.

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.

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.

We demonstrate that the development of obesity, metabolic dysfunction and type 2 diabetes, in HCD-fed mice, is accompanied by increased dermal adiposity and associated metaflammation in dWAT. Importantly, these temporal changes are also linked to disease stage-specific dermal microvascular reactivity, which may reflect adaptive mechanisms driven by metaflammation.

Aims/hypothesis. In vitro studies have suggested that glycation of LDL might be implicated in diabetic microangiopathy. We therefore investigated the in vivo effects of LDL glycated in vitro on the mouse skeletal muscle arteriolar tone. Since glycation naturally occurs during diabetes, we also tested the effects of LDL isolated from diabetic patients. Methods. In anaesthetized mice, the spinotrapezius muscle microcirculation was observed, in situ, using the orthogonal polarization spectral imaging technology. The diameter of terminal (<20 µm) and small arterioles (20-40 µm) was measured before and after a bolus intravenous injection of glycated LDL followed by a continuous perfusion (115 µg/kg/min). Results. A slight decrease of terminal and small arterioles diameter (<10%) was observed with native LDL and LDL isolated from healthy subjects. In contrast, mildly glycated LDL induced a clear vasoconstriction of arterioles (>15%), which was further increased when highly glycated LDL was perfused (>22%). LDL isolated from diabetic patients mimicked the vasoconstriction obtained with in vitro mildly glycated LDL, which underwent similar glycation as those isolated from diabetic patients. Conclusion/Interpretation. Our results show in vivo that acute perfusion of both types of glycated LDL (artificially or naturally modified), cause major microvascular modification by enhancing arteriolar tone in skeletal muscle. These findings highlight a new role of glycated LDL at the level of microvessels. We suggest that glycation of LDL could contribute to the impaired vascular reactivity observed in diabetes. [Diabetologia (2003[Diabetologia ( ) 46:1550[Diabetologia ( -1558

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