Objective-Dysregulation of inflammatory adipokines by the adipose tissue plays an important role in obesity-associated insulin resistance. Pathways leading to this dysregulation remain largely unknown. We hypothesized that the receptor for advanced glycation end products (RAGE) and the ligand N ε -(carboxymethyl)lysine (CML) are increased in adipose tissue and, moreover, that activation of the CML-RAGE axis plays an important role in obesity-associated inflammation and insulin resistance. Approach and Results-In this study, we observed a strong CML accumulation and increased expression of RAGE in adipose tissue in obesity. We confirmed in cultured human preadipocytes that adipogenesis is associated with increased levels of CML and RAGE. Moreover, CML induced a dysregulation of inflammatory adipokines in adipocytes via a RAGE-dependent pathway. To test the role of RAGE in obesity-associated inflammation further, we constructed an obese mouse model that is deficient for RAGE (ie, RAGE . RAGE-mediated trapping in adipose tissue provides a mechanism underlying CML accumulation in adipose tissue and explaining decreased CML plasma levels in obese subjects. Decreased CML plasma levels in obese individuals were strongly associated with insulin resistance. endothelial cells, and macrophages. 9 RAGE is initially identified as the receptor for advanced glycation end products (AGEs), 10 but, in addition to AGEs, RAGE also interacts with multiple members of the proinflammatory S100/calgranulin family and high motility group box 1 protein. Conclusions-RAGE-mediated9,11 Binding of these ligands to RAGE leads to activation of signaling cascade and induction of nuclear factor-κB, which can subsequently lead to the production of inflammatory mediators.9,12 Therefore, the potential role of RAGE in the regulation of inflammation suggests that RAGE might be an important mechanism contributing to obesity-associated dysregulation of adipokines and development of insulin resistance. N ε -(carboxymethyl)lysine (CML) is a major AGE and is an important ligand for RAGE.10 CML is formed on proteins by nonenzymatic glycation and oxidation reactions. 13Alternative routes for CML formation have been described, including lipid peroxidation of polyunsaturated fatty acids.14,15 In fact, lipid peroxidation is a more important source for CML formation than glycoxidation reactions.14 Because of the reaction mechanism, CML formation is increased under hyperglycemic and hyperlipidemic conditions. The adipose tissue in obese conditions is characterized by increased levels of fatty acids, lipid peroxidation, and oxidative stress. Therefore, we can deduce that obesity is also a condition in which CML formation is increased and where CML can interact with RAGE. However, the role of CML-RAGE in obesity, obesity-associated inflammation, and insulin resistance has to date not been investigated.The aim of this study was to investigate the role of CML-RAGE axis in obesity-associated inflammation and insulin resistance. In the present study, we showed in huma...

Background— Junctional adhesion molecule (JAM)-A expressed in endothelial, epithelial, and blood cells can regulate permeability and leukocyte extravasation. Atherosclerosis develops at sites of disturbed flow in large arteries, but the mechanisms guiding inflammatory cells into these predilection sites remain unknown. Methods and Results— To characterize cell-specific functions of JAM-A in atherosclerosis, we used apolipoprotein E–deficient mice with a somatic or endothelium-specific deficiency in JAM-A and bone marrow chimeras with JAM-A–deficient leukocytes. We show that impaired JAM-A expression in endothelial cells reduced mononuclear cell recruitment into the arterial wall and limited atherosclerotic lesion formation in hyperlipidemic mice. In contrast, JAM-A deficiency in bone marrow cells impeded monocyte de-adhesion, thereby increasing vascular permeability and lesion formation, whereas somatic JAM-A deletion revealed no significant effects. Regions with disturbed flow displayed a focal enrichment and luminal redistribution of endothelial JAM-A and were preferentially protected by its deficiency. The functional expression and redistribution of endothelial JAM-A was increased by oxidized low-density lipoprotein, but confined by atheroprotective laminar flow through an upregulation of microRNA (miR)-145, which repressed JAM-A. Conclusions— Our data identify endothelial JAM-A as an important effector molecule integrating atherogenic conditions to direct inflammatory cell entry at predilection sites of atherosclerosis.

BackgroundEndothelin-1 (ET-1), a long-acting paracrine mediator, is implicated in cardiovascular diseases but clinical trials with ET-receptor antagonists were not successful in some areas. We tested whether the quasi-irreversible receptor-binding of ET-1 (i) limits reversing effects of the antagonists and (ii) can be selectively dissociated by an endogenous counterbalancing mechanism.Methodology/Principal findingsIn isolated rat mesenteric resistance arteries, ETA-antagonists, endothelium-derived relaxing factors and synthetic vasodilators transiently reduced contractile effects of ET-1 but did not prevent persistent effects of the peptide. Stimuli of peri-vascular vasodilator sensory-motor nerves such as capsaicin not only reduced but also terminated long-lasting effects of ET-1. This was prevented by CGRP-receptor antagonists and was mimicked by exogenous calcitonin gene-related peptide (CGRP). Using 2-photon laser scanning microscopy in vital intact arteries, capsaicin and CGRP, but not ETA-antagonism, were observed to promote dissociation of pre-existing ET-1/ETA-receptor complexes.ConclusionsIrreversible binding and activation of ETA-receptors by ET-1 (i) occur at an antagonist-insensitive site of the receptor and (ii) are selectively terminated by endogenously released CGRP. Hence, natural stimuli of sensory-motor nerves that stimulate release of endogenous CGRP can be considered for therapy of diseases involving ET-1.

Three-dimensional cell culture and conditioning is an effective means to guide cell distribution and patterning for tissue engineered constructs such as vascular grafts. Polyacrylic acid is known as an electroresponsive polymer, capable of transforming environmental stimuli like electrical energy to mechanical forces. In this study, we developed an electrosensitive and biocompatible hydrogel-based smart device composed of acrylic acid and fibrin as a tissue engineered construct to mechanically stimulate cells. Structural properties of the hydrogel were assessed by FTIR-ATR, scanning electron microscopy, prosimetry, and swelling measurement. Distribution and alignment of porcine smooth muscle cells (pSMCs) seeded on the surface of lyophilized hydrogels were evaluated and quantified by two-photon laser scanning microscopy. Smooth muscle cell tissue constructs exposed to 2 h of pulsatile electrical stimulation showed significantly enhanced cell penetration and alignment due to dynamic changes produced by alternative swelling and deswelling, in comparison with static samples. On the basis of the results, this hydrogel under electrical stimulation works as a mechanical pump, which can direct SMC alignment and facilitate infiltration and distribution of cells throughout the structure.