Despite a significant increase in EPCs and release of cytochemokines during CABG, age is a major limiting factor for mobilization of EPCs. Further studies are necessary to improve the strategies for mobilization, ex vivo expansion, and re-transplantation of EPCs in aging patients.

Rationale Chronic exposure to ambient air-borne particulate matter <2.5 µm (PM2.5) increases cardiovascular risk. The mechanisms by which inhaled ambient particles are sensed and how these effects are systemically transduced remain elusive. Objective To investigate the molecular mechanisms by which PM2.5 mediates inflammatory responses in a mouse model of chronic exposure. Methods and Results Here we show that chronic exposure to ambient PM2.5 promotes Ly6Chigh inflammatory monocyte egress from bone-marrow and mediates their entry into tissue niches where they generate reactive oxygen species via NADPH oxidase. Toll-like receptor-4 (TLR4) and Nox2 (gp91phox) deficiency prevented monocyte NADPH oxidase activation in response to PM2.5 and was associated with restoration of systemic vascular dysfunction. TLR4 activation appeared to be a prerequisite for NAPDH oxidase activation as evidenced by reduced p47phox phosphorylation in TLR4 deficient animals. PM2.5 exposure markedly increased oxidized phospholipid derivatives of 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphorylcholine (oxPAPC) in bronchioalveolar lavage fluid. Correspondingly, exposure of bone-marrow derived macrophages to oxPAPC but not PAPC recapitulated effects of chronic PM2.5 exposure while TLR4 deficiency attenuated this response. Conclusions Taken together, our findings suggest that PM2.5 triggers an increase in oxidized phospholipids in lungs that then mediates a systemic cellular inflammatory response through TLR4/NADPH oxidase dependent mechanisms.

These data demonstrate that obesity augments prostanoid-dependent vasoconstriction and markedly increases vascular thromboxane receptor gene expression. These changes are likely to promote the development of vascular disease, hypertension and thrombosis associated with obesity.

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We conclude that LOX-1 is regulated by Ang II in vitro and in vivo, that induction of LOX-1 is mediated by the AT(1) receptor, and that repression of LOX-1 by long-term ACE inhibitor treatment may contribute to the antiatherosclerotic potential of this therapy.

AimsPatients with paroxysmal atrial fibrillation (AF) often present with typical angina pectoris and mildly elevated levels of cardiac troponin (non ST-segment elevation myocardial infarction) during an arrhythmic event. However, in a large proportion of these patients, significant coronary artery disease is excluded by coronary angiography. Here we explored the potential underlying mechanism of these events.Methods and resultsA total of 14 pigs were studied using a closed chest, rapid atrial pacing (RAP) model. In five pigs RAP was performed for 7 h (600 b.p.m.; n = 5), in five animals RAP was performed in the presence of angiotensin-II type-1-receptor (AT1-receptor) inhibitor irbesartan (RAP+Irb), and four pigs were instrumented without intervention (Sham). One-factor analysis of variance was performed to assess differences between and within the three groups. Simultaneous measurements of fractional flow reserve (FFR) and coronary flow reserve (CFR) before, during, and after RAP demonstrated unchanged FFR (P = 0.327), but decreased CFR during RAP (RAP: 67.7 ± 7.2%, sham: 97.2 ± 2.8%, RAP+Irb: 93.2 ± 3.3; P = 0.0013) indicating abnormal left ventricular (LV) microcirculation. Alterations in microcirculatory blood flow were accompanied by elevated ventricular expression of NADPH oxidase subunit Nox2 (P = 0.039), lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1, P = 0.004), and F2-isoprostane levels (P = 0.008) suggesting RAP-related oxidative stress. Plasma concentrations of cardiac troponin-I (cTn-I) increased in RAP (RAP: 613.3 ± 125.8 pmol/L vs. sham: 82.5 ± 12.5 pmol/L; P = 0.013), whereas protein levels of eNOS and LV function remained unchanged. RAP+Irb prevented the increase of Nox2, LOX-1, and F2-isoprostanes, and abolished the impairment of microvascular blood flow.ConclusionRapid atrial pacing induces AT1-receptor-mediated oxidative stress in LV myocardium that is accompanied by impaired microvascular blood flow and cTn-I release. These findings provide a plausible mechanism for the frequently observed cTn-I elevation accompanied with typical angina pectoris symptoms in patients with paroxysmal AF and normal (non-stenotic) coronary arteries.

Abstract-In the C57BL/6J mice model, we investigated whether obesity affects the function or expression of components of the tissue renin-angiotensin system and whether endothelin (ET)-1 contributes to these changes. ACE activity (nmol ⅐ L His-Leu ⅐ mg protein Ϫ1 ) was measured in lung, kidney, and liver in control (receiving standard chow) and obese animals treated for 30 weeks with a high-fat, low cholesterol diet alone or in combination with LU135252, an orally active ET A receptor antagonist. ACE mRNA expression was measured in the kidney, and the effects of LU135252 on purified human ACE were determined. Aortic and renal tissue ET-1 protein content was measured, and the vascular contractility to angiotensin II was assessed. Obesity was associated with a tissue-specific increase in ACE activity in the kidney (55Ϯ4 versus 33Ϯ3 nmol/L) but not in the lung (34Ϯ2 versus 32Ϯ2 nmol/L). Long-term LU135252 treatment completely prevented this activation (13.3Ϯ0.3 versus 55Ϯ4 nmol/L, PϽ0.05) independent of ACE mRNA expression, body weight, or renal ET-1 protein but did not affect pulmonary or hepatic ACE activity. Obesity potentiated contractions in response to angiotensin II in the aorta (from 6Ϯ2% to 33Ϯ5% KCl) but not in the carotid artery (4Ϯ1% to 3.6Ϯ1% KCl), an effect that was completely prevented with LU135252 treatment (6Ϯ0.4% versus 33Ϯ5% KCl). No effect of LU135252 on purified ACE was observed. Thus, obesity is associated with the activation of renal ACE in vivo independent of its mRNA expression and enhanced vascular contractility to angiotensin II. These effects are regulated by ET in an organ-specific manner, providing novel mechanisms by which ET antagonists may exert organ protection.

Background-Experimental studies indicate that interleukin-6 (IL-6)-related cytokines, signaling via the shared receptor gp130, Janus kinases (JAKs), and signal transducers and activators of transcription (STATs), provide a critical cardiomyocyte survival pathway in vivo. Little is known about the activation of this signaling pathway in the myocardia of patients with end-stage dilated cardiomyopathy (DCM). Methods and Results-We performed a comprehensive expression and activation analysis of IL-6 -related cytokines, receptors, signal transducers, and signal transduction inhibitors in left ventricular (LV) myocardia from patients with DCM (nϭ10) and non-failing (NF) donor hearts (nϭ5 Key Words: cardiomyopathy Ⅲ interleukins Ⅲ signal transduction D ilated cardiomyopathy (DCM) represents a common end-stage disease state of the myocardium in response to different environmental and genetic factors, a fact that has led to the proposition of shared signaling pathways for cardiac dilation and failure. 1 In this regard, a growing body of evidence indicates that interleukin-6 (IL-6)-related cytokines signaling via the shared receptor gp130 provide a critical myocyte survival pathway in vivo. Most notably, genetargeted mice with a cardiomyocyte-restricted deletion of gp130 develop massive cardiomyocyte apoptosis and dilated cardiomyopathy when subjected to biomechanical stress. 2 A prevailing concept predicts that an intricate balance between cardiomyocyte hypertrophy and apoptosis determines heart failure progression. 1 In this regard, the Janus kinases-signal transducers and activators of transcription (JAK-STAT) signaling pathway has been shown to mediate hypertrophic and cytoprotective effects of gp130 activation in cardiomyocytes. 2-8 IL-6 -related cytokines potently activate gp130, which in turn promotes tyrosine-phosphorylation (ie, activation) of JAKs and cytoplasmic latent transcription factors of the STAT family. 9 Signaling via gp130 and JAK-STAT is controlled in a negative-feedback fashion by a family of proteins referred to as suppressors of cytokine signaling, including SOCS1 and SOCS3. 10,11 Despite increasing evidence implicating IL-6 -related cytokines, gp130, and JAK-STAT as a critical myocyte survival pathway, little is known regarding expression and activation of this pathway in patients with DCM. In the present study, we have conducted a comprehensive expression and activation analysis of the gp130-JAK-STAT signaling cascade in left ventricular (LV) myocardia from patients with DCM. Methods Patient PopulationLV myocardium was obtained from patients undergoing heart transplantation because of end-stage DCM (nϭ10; mean age: 44Ϯ13 years; New York Heart Association functional classes III and IV; LV ejection fraction: 16Ϯ7%; LV end-diastolic diameter: 65Ϯ14 mm). ImmunohistochemistryImmunohistochemistry was performed on serial sections from NF and DCM hearts using antibodies from New England Biolabs (Beverly, Mass, JAK2), Cell Signaling Technology (STAT3), Biomeda (Foster City, Calif, skeletal muscle ␣-actin...