Rationale Epidemiologic evidence indicates that exposures to fine particulate matter air pollution (PM2.5) contribute to global burden of disease, primarily as a result of increased risk of cardiovascular morbidity and mortality. However, mechanisms by which PM2.5 exposure induces cardiovascular injury remain unclear. PM2.5-induced endothelial dysfunction and systemic inflammation have been implicated, but direct evidence is lacking. Objective To examine whether acute exposure to PM2.5 is associated with endothelial injury and systemic inflammation. Methods and Results Blood was collected from healthy, non-smoking, young adults over three study periods that included episodes of elevated PM2.5 levels. Microparticles and immune cells in blood were measured by flow cytometry, and plasma cytokine/growth factors were measured using multiplexing laser beads. PM2.5 exposure was associated with elevated levels of endothelial microparticles (annexin V+/CD41−/CD31+) including subtypes expressing arterial-, venous-, and lung-specific markers, but not microparticles expressing CD62+. These changes were accompanied by suppressed circulating levels of pro-angiogenic growth factors (EGF, sCD40L, PDGF, RANTES, GROα, and VEGF), and an increase in the levels of anti-angiogenic (TNFα, IP-10) and proinflammatory cytokines (MCP-1, MIP-1α/β, IL-6, and IL-1β), and markers of endothelial adhesion (sICAM-1 and sVCAM-1). PM2.5 exposure also was associated with an inflammatory response characterized by elevated levels of circulating CD14+, CD16+, CD4+, and CD8+, but not CD19+ cells. Conclusions Episodic PM2.5 exposures are associated with increased endothelial cell apoptosis, an anti-angiogenic plasma profile, and elevated levels of circulating monocytes, and T, but not B, lymphocytes. These changes could contribute to the pathogenic sequelae of atherogenesis and acute coronary events.

NF‐κB is constitutively activated in most human pancreatic adenocarcinoma, which is a deadly malignancy with a 5‐year survival rate of about 5%. In this work, we investigate whether microRNAs (miRNAs) contribute to NF‐κB activation in pancreatic cancer. We demonstrate that miR‐301a down‐regulates NF‐κB‐repressing factor (Nkrf) and elevates NF‐κB activation. As NF‐κB promotes the transcription of miR‐301a, our results support a positive feedback loop as a mechanism for persistent NF‐κB activation, in which miR‐301a represses Nkrf to elevate NF‐κB activity, which in turn promotes miR‐301a transcription. Nkrf was found down‐regulated and miR‐301a up‐regulated in human pancreatic adenocarcinoma tissues. Moreover, miR‐301a inhibition or Nkrf up‐regulation in pancreatic cancer cells led to reduced NF‐κB target gene expression and attenuated xenograft tumour growth, indicating that miR‐301a overexpression contributes to NF‐κB activation. Revealing this novel mechanism of NF‐κB activation by an miRNA offers new avenues for therapeutic interventions against pancreatic cancer.

Rationale Endothelial progenitor cells (EPCs) respond to SDF-1 through receptors CXCR7 and CXCR4. Whether SDF-1 receptors involves in diabetes induced EPCs dysfunction remains unknown. Objective To determine the role of SDF-1 receptors in diabetic EPCs dysfunction. Methods and Results CXCR7 expression, but not CXCR4 was reduced in EPCs from db/db mice, which coincided with impaired tube formation. Knockdown of CXCR7 impaired tube formation of EPCs from normal mice, while up-regulation of CXCR7 rescued angiogenic function of EPCs from db/db mice. In normal EPCs treated with oxidized low-density lipoprotein (ox-LDL) or high glucose (HG) also reduced CXCR7 expression, impaired tube formation and increased oxidative stress and apoptosis. The damaging effects of ox-LDL or HG were markedly reduced by SDF-1 pretreatment in EPCs transduced with CXCR7 lentivirus (CXCR7-EPCs) but not in EPCs transduced with control lentivirus (Null-EPCs). Most importantly, CXCR7-EPCs were superior to Null-EPCs for therapy of ischemic limbs in db/db mice. Mechanistic studies demonstrated that ox-LDL or HG inhibited Akt and GSK-3β phosphorylation, nuclear export of Fyn and nuclear localization of Nrf2, blunting Nrf2 downstream target genes HO-1, NQO-1 and catalase, and inducing an increase in EPC oxidative stress. This destructive cascade was blocked by SDF-1 treatment in CXCR7-EPCs. Furthermore, inhibition of PI3K/Akt prevented SDF-1/CXCR7-mediated Nrf2 activation and blocked angiogenic repair. Moreover, Nrf2 knockdown almost completely abolished the protective effects of SDF-1/CXCR7 on EPC function in vitro and in vivo. Conclusions Elevated expression of CXCR7 enhances EPC resistance to diabetes-induced oxidative damage and improves therapeutic efficacy of EPCs in treating diabetic limb ischemia. The benefits of CXCR7 are mediated predominantly by an Akt/GSK-3β/Fyn pathway via increased activity of Nrf2.

Acetaldehyde, acrolein, and formaldehyde are the principal toxic aldehydes present in cigarette smoke and contribute to the risk of cardiovascular disease and noncancerous pulmonary disease. The rapid growth of the use of electronic cigarettes (e-cigarettes) has raised concerns over emissions of these harmful aldehydes. This work determines emissions of these aldehydes in both free and bound (aldehyde–hemiacetal) forms and other carbonyls from the use of e-cigarettes. A novel silicon microreactor with a coating phase of 4-(2-aminooxyethyl)-morpholin-4-ium chloride (AMAH) was used to trap carbonyl compounds in the aerosols of e-cigarettes via oximation reactions. AMAH–aldehyde adducts were measured using gas chromatography–mass spectrometry. 1H nuclear magnetic resonance spectroscopy was used to analyze hemiacetals in the aerosols. These aldehydes were detected in the aerosols of all e-cigarettes. Newer-generation e-cigarette devices generated more aldehydes than the first-generation e-cigarettes because of higher battery power output. Formaldehyde–hemiacetal was detected in the aerosols generated from some e-liquids using the newer e-cigarette devices at a battery power output of 11.7 W and above. The emission of these aldehydes from all e-cigarettes, especially higher levels of aldehydes from the newer-generation e-cigarette devices, indicates the risk of using e-cigarettes.

Background Polychlorinated biphenyls (PCBs) are persistent environmental pollutants which are detectable in the serum of all American adults. Amongst PCB congeners, PCB 153 has the highest serum level. PCBs have been dose-dependently associated with obesity, metabolic syndrome, and nonalcoholic fatty liver disease (NAFLD) in epidemiological studies. Objective The purpose of this study is to determine mechanisms by which PCB 153 worsens diet-induced obesity and NAFLD in male mice fed a high fat diet (HFD). Methods Male C57BL6/J mice were fed either control or 42% milk fat diet for 12 weeks with or without PCB 153 co-exposure (50 mg/kg i.p. × 4). Glucose tolerance test was performed, and plasma and tissues were obtained at necropsy for measurements of adipocytokine levels, histology and gene expression. Results In control diet-fed mice, addition of PCB 153 had minimal effects on any of the measured parameters. However, PCB 153 treatment in high fat-fed mice was associated with increased visceral adiposity, hepatic steatosis and plasma adipokines including adiponectin, leptin, resistin and plasminogen activator inhibitor-1 levels. Likewise, co-exposure reduced expression of hepatic genes implicated in β-oxidation while increasing the expression of genes associated with lipid biosynthesis. Regardless of diet, PCB 153 had no effect on insulin resistance or tumor necrosis factor alpha levels. Conclusion PCB 153 is an obesogen which exacerbates hepatic steatosis; alters adipocytokines; and disrupts normal hepatic lipid metabolism when administered with HFD, but not control diet. Because all U.S. adults have been exposed to PCB 153, this particular nutrient-toxicant interaction potentially impacts human obesity/NAFLD.

Rationale: Acute and chronic exposures to airborne particulate matter (PM) have been linked in epidemiological studies to a wide spectrum of cardiovascular disorders that are characterized by a dysfunctional endothelium. The pathophysiological mechanisms underlying these associations are unclear. Objective: To examine whether exposure to fine PM with an aerodynamic diameter of <2.5 m (PM 2.5 ) affects the circulating levels of endothelial progenitor cell (EPC) populations, systemic inflammation and coagulation. Methods and Results: Phenotypically distinct EPC populations were quantified by flow cytometry in young (18 to 25 years) adult humans exposed to episodic increases in PM 2.5 along the Wasatch Mountain Front in Utah. In addition, Sca-1 ؉ /Flk-1 ؉ cells were measured in the peripheral blood of mice exposed to concentrated particles from ambient air in Louisville, Ky. In both studies, PM exposure was negatively correlated with circulating EPC levels. In humans, statistically significant associations between PM 2.5 exposure and the plasma levels of platelet-monocyte aggregates, high-density lipoprotein, and nonalbumin protein were also observed. Episodic increases in PM 2.5 did not change plasma levels of C-reactive protein, interleukin-1␤, interleukin-6, fibrinogen, or serum amyloid A. Conclusions: Episodic exposure to PM 2.5 induces reversible vascular injury, reflected in part by depletion of circulating EPC levels, and increases in platelet activation and the plasma level of high-density lipoprotein. These changes were also accompanied by an increase in nonalbumin protein and may be related to mechanisms by which exposure to particulate air pollution increases the risk of cardiovascular disease and adverse cardiovas- Key Words: endothelial progenitor cell Ⅲ airborne particulate matter Ⅲ pollution Ⅲ endothelial repair A cute and chronic exposure to elevated levels of fine airborne particulate matter (PM) is associated with an increase in the incidence of adverse cardiovascular events, 1,2 atherogenesis, cardiovascular disease (CVD) risk, and cardiovascular mortality. In urban environments, fine PM (PM with aerodynamic diameter of Ͻ2.5 m [PM 2.5 ]) is generated mostly by fossil fuel combustion in automobiles or by industrial processes. Although several mechanisms have been proposed to account for the link between PM exposure and CVD risk, endothelial dysfunction has emerged as a key feature of PM toxicity. Inhalation of concentrated PM 2.5 induces acute conduit artery vasoconstriction in humans and chronic deficits in endothelium-mediated vasodilation in mice. 1,2 The adult endothelium is a differentiated cell layer that provides a nonthrombotic interface between parenchymal cells and peripheral blood. Defects in its function arise because of the upregulated expression of proinflammatory and prothrombotic molecules or from defective, endogenous repair capacity. Evidence from multiple studies suggests that the endothelium is continually repaired by progenitor cells mobilized from specific niches such as th...

BackgroundAcrolein is a reactive aldehyde present in high amounts in coal, wood, paper, and tobacco smoke. It is also generated endogenously by lipid peroxidation and the oxidation of amino acids by myeloperoxidase. In animals, acrolein exposure is associated with the suppression of circulating progenitor cells and increases in thrombosis and atherogenesis. The purpose of this study was to determine whether acrolein exposure in humans is also associated with increased cardiovascular disease (CVD) risk.Methods and ResultsAcrolein exposure was assessed in 211 participants of the Louisville Healthy Heart Study with moderate to high (CVD) risk by measuring the urinary levels of the major acrolein metabolite—3‐hydroxypropylmercapturic acid (3‐HPMA). Generalized linear models were used to assess the association between acrolein exposure and parameters of CVD risk, and adjusted for potential demographic confounders. Urinary 3‐HPMA levels were higher in smokers than nonsmokers and were positively correlated with urinary cotinine levels. Urinary 3‐HPMA levels were inversely related to levels of both early (AC133+) and late (AC133−) circulating angiogenic cells. In smokers as well as nonsmokers, 3‐HPMA levels were positively associated with both increased levels of platelet–leukocyte aggregates and the Framingham Risk Score. No association was observed between 3‐HPMA and plasma fibrinogen. Levels of C‐reactive protein were associated with 3‐HPMA levels in nonsmokers only.ConclusionsRegardless of its source, acrolein exposure is associated with platelet activation and suppression of circulating angiogenic cell levels, as well as increased CVD risk.

Background Exercise promotes metabolic remodeling in the heart, which is associated with physiologic cardiac growth; however, it is not known whether or how physical activity-induced changes in cardiac metabolism cause myocardial remodeling. In this study, we tested whether exercise-mediated changes in cardiomyocyte glucose metabolism are important for physiologic cardiac growth. Methods We used radiometric, immunologic, metabolomic, and biochemical assays to measure changes in myocardial glucose metabolism in mice subjected to acute and chronic treadmill exercise. To assess the relevance of changes in glycolytic activity, we determined how cardiac-specific expression of mutant forms of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK2) affect cardiac structure, function, metabolism, and gene programs relevant to cardiac remodeling. Metabolomic and transcriptomic screenings were used to identify metabolic pathways and gene sets regulated by glycolytic activity in the heart. Results Exercise acutely decreased glucose utilization via glycolysis by modulating circulating substrates and reducing phosphofructokinase activity; however, upon exercise adaptation and recovery there was an increase in myocardial phosphofructokinase activity and glycolysis. Cardiac-specific expression of a kinase-deficient PFK2 transgene (GlycoLo mice) lowered glycolytic rate and regulated the expression of genes known to promote cardiac growth. Hearts of GlycoLo mice had larger myocytes, enhanced cardiac function, and higher capillary-to-myocyte ratios. Expression of phosphatase-deficient PFK2 in the heart (GlycoHi mice) increased glucose utilization and promoted a more pathological form of hypertrophy devoid of transcriptional activation of the physiologic cardiac growth program. Modulation of phosphofructokinase activity was sufficient to regulate the glucose-fatty acid cycle in the heart; however, metabolic inflexibility caused by invariantly low or high phosphofructokinase activity caused modest mitochondrial damage. Transcriptomic analyses showed that glycolysis regulates the expression of key genes involved in cardiac metabolism and remodeling. Conclusions Exercise-induced decreases in glycolytic activity stimulate physiologic cardiac remodeling, and metabolic flexibility is important for maintaining mitochondrial health in the heart.