Objective—: Vascular precursor cells with angiogenic potentials are important for tissue repair, which is impaired in diabetes mellitus. MicroRNAs are recently discovered key regulators of gene expression, but their role in vascular precursor cell–mediated angiogenesis in diabetes mellitus is unknown. We tested the hypothesis that the microRNA miR-27b rescues impaired bone marrow–derived angiogenic cell (BMAC) function in vitro and in vivo in type 2 diabetic mice. Approach and Results—: BMACs from adult male type 2 diabetic db/db and from normal littermate db/+ mice were used. miR-27b expression was decreased in db/db BMACs. miR-27b mimic improved db/db BMAC function, including proliferation, adhesion, tube formation, and delayed apoptosis, but it did not affect migration. Elevated thrombospondin-1 (TSP-1) protein in db/db BMACs was suppressed on miR-27b mimic transfection. Inhibition of miR-27b in db/+ BMACs reduced angiogenesis, which was reversed by TSP-1 small interfering RNA (siRNA). miR-27b suppressed the pro-oxidant protein p66 ^shc and mitochondrial oxidative stress, contributing to its protection of BMAC function. miR-27b also suppressed semaphorin 6A to improve BMAC function in diabetes mellitus. Luciferase binding assay suggested that miR-27b directly targeted TSP-1, TSP-2, p66 ^shc , and semaphorin 6A. miR-27b improved topical cell therapy of diabetic BMACs on diabetic skin wound closure, with a concomitant augmentation of wound perfusion and capillary formation. Normal BMAC therapy with miR-27b inhibition demonstrated reduced efficacy in wound closure, perfusion, and capillary formation. Local miR-27b delivery partly improved wound healing in diabetic mice. Conclusions—: miR-27b rescues impaired BMAC angiogenesis via TSP-1 suppression, semaphorin 6A expression, and p66shc-dependent mitochondrial oxidative stress and improves BMAC therapy in wound healing in type 2 diabetic mice.

A high-fat diet causes liver disease by suppressing IRE1α-regulated microRNA biogenesis.

High mobility group box 1 (HMGB1) plays an important role in the pathologic processes of endothelial permeability under oxidative stress. Trophoblast oxidative stress has been implicated in the pathophysiology of preeclampsia (PE). HMGB1 serum levels are increased in PE. However, the potential roles of HMGB1 in endothelial permeability in PE remain unclear. We assessed the effects of the hypoxic trophoblast on the permeability of the endothelial monolayer. Our results showed that the hypoxic trophoblast displayed higher HMGB1 mRNA, intracellular HMGB1 protein, and HMGB1 in conditioned medium than those of the normoxic trophoblast did. The hypoxic trophoblast conditioned medium increased the endothelial monolayer permeability and increased TLR 4 and caveolin-1 (CAV-1) protein expression in endothelial cells, which was inhibited by glycyrrhizic acid and HMGB1 small interfering RNA transfection to trophoblasts before hypoxia. The increased endothelial permeability induced by hypoxic trophoblast conditioned medium could be inhibited with TLR4 or CAV-1 gene silencing in endothelial cells. Immunoprecipitation showed that CAV-1 and TLR4 are colocalized in HUVECs and C57BL/6 mouse kidney. TLR4 small interfering RNA suppressed CAV-1 protein expression in endothelial cells upon stimulation of hypoxic trophoblast conditioned medium or HMGB1. We conclude that hypoxic trophoblasts play an important role in the mechanism of general edema (including protein urine) in PE via increasing endothelial monolayer permeability through the HMGB1/TLR4/CAV-1 pathway.

Reduced arterial elasticity is a hallmark of ageing in healthy humans and appears to occur independently of coexisting disease processes. Endothelial-cell injury and dysfunction may be responsible for this fall in arterial elasticity. We hypothesized that circulating endothelial progenitor cells (EPCs) are involved in endothelial repair and that lack of EPCs contributes to impaired arterial elasticity. A total of 56 healthy male volunteers were divided into young (n=26) and elderly (n=30) groups. Large and small artery elasticity indices were noninvasively assessed using pulse wave analysis. The number of circulating EPCs was measured by using flow cytometry. Cells demonstrating DiI-acLDL and FITC-ulex lectin double-positive fluorescence were identified as EPCs. C1 large artery elasticity and C2 small artery elasticity indices were significantly reduced in the elderly group compared with the young group (11.73±1.45 vs 16.88±1.69 ml/mm Hg × 10, P<0.001; 8.40±1.45 vs 10.58±1.18 ml/mm Hg × 100, P<0.001, respectively). In parallel, the number of circulating EPCs was significantly reduced in the elderly group compared with the young group (0.13±0.02 vs 0.17±0.04%, P<0.05). The number of circulating EPCs correlated with C1 large and C2 small artery elasticity indices (r=0.47, P<0.01; r=0.4, P<0.01). The present findings suggest that the fall in circulating EPCs with subsequently impaired endothelial-cell repair and function contributes to reduced arterial elasticity in humans with ageing. The decrease in circulating EPCs may serve as a surrogate biologic measure of vascular function and human age.

Objective—: Endoluminal vascular interventions such as angioplasty initiate a sterile inflammatory response resulting from local tissue damage. This response drives the development of intimal hyperplasia (IH) that, in turn, can lead to arterial occlusion. We hypothesized that the ubiquitous nuclear protein and damage-associated molecular pattern molecule, high-mobility group box 1 (HMGB1), is one of the endogenous mediators that activates processes leading to IH after endoluminal injury to the arterial wall. The aim of this study is to investigate whether approaches that reduce the levels of HMGB1 or inhibit its activity suppresses IH after arterial injury. Approach and Results—: Here, we show that HMGB1 regulates IH in a mouse carotid wire injury model. Induced genetic deletion or neutralization of HMGB1 prevents IH, monocyte recruitment, and smooth muscle cell growth factor production after endoluminal carotid artery injury. A specific inhibitor of HMGB1 myeloid differentiation factor 2–toll-like receptor 4 (TLR4) interaction, P5779, also significantly inhibits IH. HMGB1 deletion is mimicked in this model by global deletion of TLR4 and partially replicated by myeloid-specific deletion of TLR4 but not TLR2 or receptor for advanced glycation endproducts deletion. The specific HMGB1 isoform known to activate TLR4 signaling (disulfide HMGB1) stimulates smooth muscle cell to migrate and produce monocyte chemotactic protein 1/CCL2) via TLR4. Macrophages produce smooth muscle cell mitogens in response to disulfide HMGB1 also in a TLR4/myeloid differentiation primary response gene (88)/Trif-dependent manner. Conclusions—: These findings place HMGB1 and its receptor, TLR4 as critical regulators of the events that drive the inflammation leading to IH after endoluminal arterial injury and identify this pathway as a possible therapeutic target to limit IH to attenuate damage-associated molecular pattern molecule–mediated vascular inflammatory responses.