GPER activation protects against epithelial barrier disruption by Staphylococcus aureus α-toxin

Sex bias in innate defense against Staphylococcus aureus skin and soft tissue infection (SSTI) is dependent on both estrogen production by the host and S. aureus secretion of the virulence factor, α-hemolysin (Hla). The impact of estrogen signaling on the immune system is most often studied in terms of the nuclear estrogen receptors ERα and ERβ. However, the potential contribution of the G protein-coupled estrogen receptor (GPER) to innate defense against infectious disease, particularly with respect to skin infection, has not been addressed. Using a murine model of SSTI, we found that GPER activation with the highly selective agonist G-1 limits S. aureus SSTI and Hla-mediated pathogenesis, effects that were absent in GPER knockout mice. Specifically, G-1 reduced Hla-mediated skin lesion formation and pro-inflammatory cytokine production, while increasing bacterial clearance. In vitro, G-1 reduced surface expression of the Hla receptor, ADAM10, in a human keratinocyte cell line and increased resistance to Hla-mediated permeability barrier disruption. This novel role for GPER activation in skin innate defense against infectious disease suggests that G-1 may have clinical utility in patients with epithelial permeability barrier dysfunction or who are otherwise at increased risk of S. aureus infection, including those with atopic dermatitis or cancer.

Muscle-specific regulation of right ventricular transcriptional responses to chronic hypoxia-induced hypertrophy by the muscle ring finger-1 (MuRF1) ubiquitin ligase in mice

BACKGROUND

We recently identified a role for the muscle-specific ubiquitin ligase MuRF1 in right-sided heart failure secondary to pulmonary hypertension induced by chronic hypoxia (CH). MuRF1-/- mice exposed to CH are resistant to right ventricular (RV) dysfunction whereas MuRF1 Tg + mice exhibit impaired function indicative of heart failure. The present study was undertaken to understand the underlying transcriptional alterations in the RV of MuRF1-/- and MuRF1 Tg + mice.

METHODS

Microarray analysis was performed on RNA isolated from the RV of MuRF1-/-, MuRF1 Tg+, and wild-type control mice exposed to CH.

RESULTS

MuRF1-/- RV differentially expressed 590 genes in response to CH. Analysis of the top 66 genes (> 2-fold or < - 2-fold) revealed significant associations with oxidoreductase, transcription regulation, and transmembrane component annotations. The significant genes had promoters enriched for HOXD12, HOXC13, and RREB-1 protein transcription factor binding sites. MuRF1 Tg + RV differentially expressed 150 genes in response to CH. Analysis of the top 45 genes (> 3-fold or < - 3-fold) revealed significant associations with oxidoreductase-metabolic, glycoprotein-transmembrane-integral proteins, and alternative splicing/splice variant annotations. The significant genes were enriched for promoters with ZIC1 protein transcription factor binding sites.

CONCLUSIONS

The differentially expressed genes in MuRF1-/- and MuRF1 Tg + RV after CH have common functional annotations related to oxidoreductase (including antioxidant) and transmembrane component functions. Moreover, the functionally-enhanced MuRF1-/- hearts regulate genes related to transcription, homeobox proteins, and kinases/phosphorylation. These studies also reveal potential indirect effects of MuRF1 through regulating Rreb-1, and they reveal mechanisms by which MuRF1 may transcriptionally regulate anti-oxidant systems in the face of right heart failure.

Early life stress, air pollution, inflammation, and disease: An integrative review and immunologic model of social-environmental adversity and lifespan health

Socially disadvantaged individuals are at greater risk for simultaneously being exposed to adverse social and environmental conditions. Although the mechanisms underlying joint effects remain unclear, one hypothesis is that toxic social and environmental exposures have synergistic effects on inflammatory processes that underlie the development of chronic diseases, including cardiovascular disease, diabetes, depression, and certain types of cancer. In the present review, we examine how exposure to two risk factors that commonly occur with social disadvantage-early life stress and air pollution-affect health. Specifically, we identify neuroimmunologic pathways that could link early life stress, inflammation, air pollution, and poor health, and use this information to propose an integrated, multi-level model that describes how these factors may interact and cause health disparity across individuals based on social disadvantage. This model highlights the importance of interdisciplinary research considering multiple exposures across domains and the potential for synergistic, cross-domain effects on health, and may help identify factors that could potentially be targeted to reduce disease risk and improve lifespan health.

Arsenic association with circulating oxidized low-density lipoprotein in a Native American community

More than 500 abandoned uranium (U) mines within the Navajo Nation contribute U, arsenic (As) and other metals to groundwater, soil and potentially air through airborne transport. The adverse cardiovascular health effects attributed to cumulative exposure to these metals remains uncertain. The aim of this study was to examine whether environmental exposure to these metals may promote or exacerbate the oxidation of low-density lipoprotein (LDL) cholesterol in this Native American population. The correlation of cardiovascular biomarkers (oxidized LDL (oxLDL) and C-reactive protein (CRP)) from a Navajo cohort (n = 252) with mean annual As and U intakes from water and urine metals was estimated using linear regression. Proof-of-concept assays were performed to investigate whether As and U directly oxidize human LDL. Mean annual As intake from water was positively and significantly associated with oxLDL, but not CRP in this study population, while U intake estimates were negatively associated with oxLDL. In an acellular system, As, but not U, directly oxidized the apolipoprotein B-100 component of purified human LDL. Neither metal promoted lipid peroxidation of the LDL particle. Both the population and lab results are consistent with the hypothesis that As promotes oxidation of LDL, a crucial step in vascular inflammation and chronic vascular disease. Conversely, for outcomes related to U, negative associations were observed between U intake and oxLDL, and U only minimally altered human LDL in direct exposure experiments. Only urine U was correlated with CRP, whereas no other metals in water or urine were apparently reliable predictors of this inflammatory marker.

Vaccaro M, Yoshimori T, Yu L, Zhang H, Klionsky DJ. Autophagy, Inflammation, and Metabolism (AIM) Center of Biomedical Research Excellence: supporting the next generation of autophagy researchers and fostering international collaborations

Recently, NIH has funded a center for autophagy research named the Autophagy, Inflammation, and Metabolism (AIM) Center of Biomedical Research Excellence, located at the University of New Mexico Health Science Center (UNM HSC), with aspirations to promote autophagy research locally, nationally, and internationally. The center has 3 major missions: (i) to support junior faculty in their endeavors to develop investigations in this area and obtain independent funding; (ii) to develop and provide technological platforms to advance autophagy research with emphasis on cellular approaches for high quality reproducible research; and (iii) to foster international collaborations through the formation of an International Council of Affiliate Members and through hosting national and international workshops and symposia. Scientifically, the AIM center is focused on autophagy and its intersections with other processes, with emphasis on both fundamental discoveries and applied translational research.

Residential proximity to abandoned uranium mines and serum inflammatory potential in chronically exposed Navajo communities

Members of the Navajo Nation, who possess a high prevalence of cardiometabolic disease, reside near hundreds of local abandoned uranium mines (AUM), which contribute uranium, arsenic and other metals to the soil, water and air. We recently reported that hypertension is associated with mine waste exposures in this population. Inflammation is a major player in the development of numerous vascular ailments. Our previous work establishing that specific transcriptional responses of cultured endothelial cells treated with human serum can reveal relative circulating inflammatory potential in a manner responsive to pollutant exposures, providing a model to assess responses associated with exposure to these waste materials in this population. To investigate a potential link between exposures to AUM and serum inflammatory potential in affected communities, primary human coronary artery endothelial cells were treated for 4 h with serum provided by Navajo study participants (n=145). Endothelial transcriptional responses of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and chemokine ligand 2 (CCL2) were measured. These transcriptional responses were then linked to AUM exposure metrics, including surface area-weighted AUM proximity and estimated oral intake of metals. AUM proximity strongly predicted endothelial transcriptional responses to serum including CCL2, VCAM-1 and ICAM-1 (P<0.0001 for each), whereas annual water intakes of arsenic and uranium did not, even after controlling for all major effect modifiers. Inflammatory potential associated with proximity to AUMs, but not oral intake of specific metals, additionally suggests a role for inhalation exposure as a contributor to cardiovascular disease.

Ambient Ultrafine Particle Ingestion Alters Gut Microbiota in Association with Increased Atherogenic Lipid Metabolites

Ambient particulate matter (PM) exposure is associated with atherosclerosis and inflammatory bowel disease. Ultrafine particles (UFP, d_p < 0.1–0.2 μm) are redox active components of PM. We hypothesized that orally ingested UFP promoted atherogenic lipid metabolites in both the intestine and plasma via altered gut microbiota composition. Low density lipoprotein receptor-null (Ldlr^−/−) mice on a high-fat diet were orally administered with vehicle control or UFP (40 μg/mouse/day) for 3 days a week. After 10 weeks, UFP ingested mice developed macrophage and neutrophil infiltration in the intestinal villi, accompanied by elevated cholesterol but reduced coprostanol levels in the cecum, as well as elevated atherogenic lysophosphatidylcholine (LPC 18:1) and lysophosphatidic acids (LPAs) in the intestine and plasma. At the phylum level, Principle Component Analysis revealed significant segregation of microbiota compositions which was validated by Beta diversity analysis. UFP-exposed mice developed increased abundance in Verrocomicrobia but decreased Actinobacteria, Cyanobacteria, and Firmicutes as well as a reduced diversity in microbiome. Spearman’s analysis negatively correlated Actinobacteria with cecal cholesterol, intestinal and plasma LPC18:1, and Firmicutes and Cyanobacteria with plasma LPC 18:1. Thus, ultrafine particles ingestion alters gut microbiota composition, accompanied by increased atherogenic lipid metabolites. These findings implicate the gut-vascular axis in a atherosclerosis model.

Inflammatory and Vasoactive Effects of Serum Following Inhalation of Varied Complex Mixtures

Chronic cardiovascular disease is associated with air pollution exposure in epidemiology and toxicology studies. Inhaled toxicants can induce changes in serum bioactivity that impact endothelial inflammatory gene expression in vitro and impair vasorelaxation ex vivo, which are common precursors to atherosclerosis. Comparisons between single pollutants and common combustion mixtures, in terms of driving such serum inflammatory and vasoactive effects, have not been characterized. Healthy C57BL/6 mice were exposed to a single 6-h period of contrasting pollutant atmospheres: road dust, mixed vehicle emissions (MVE; a combination of gasoline and diesel engine emissions) particulate matter, mixed vehicle emissions gases, road dust plus ozone, road dust plus MVE, and hardwood smoke. Serum obtained from mice 24 h after these exposures was used as a stimulus to assess inflammatory potential in two assays: incubated with primary murine cerebrovascular endothelial cells for 4 h to measure inflammatory gene expression or applied to naïve aortic rings in an ex vivo myographic preparation. Road dust and wood smoke exposures were most potent at inducing inflammatory gene expression, while MVE atmospheres and wood smoke were most potent at impairing vasorelaxation to acetylcholine. Responses are consistent with recent reports on MVE toxicity, but reveal novel serum bioactivity related to wood smoke and road dust. These studies suggest that the compositional changes in serum and resultant bioactivity following inhalation exposure to pollutants may be highly dependent on the composition of mixtures.

Surface area-dependence of gas-particle interactions influences pulmonary and neuroinflammatory outcomes

Background

Deleterious consequences of exposure to traffic emissions may derive from interactions between carbonaceous particulate matter (PM) and gaseous components in a manner that is dependent on the surface area or complexity of the particles. To determine the validity of this hypothesis, we examined pulmonary and neurological inflammatory outcomes in C57BL/6 and apolipoprotein E knockout (ApoE^−/−) male mice after acute and chronic exposure to vehicle engine-derived particulate matter, generated as ultrafine (UFP) and fine (FP) sizes, with additional exposures using UFP or FP combined with gaseous copollutants derived from fresh gasoline and diesel emissions, labeled as UFP + G and FP + G.

Results

The UFP and UFP + G exposure groups resulted in the most profound pulmonary and neuroinflammatory effects. Phagocytosis of UFP + G particles via resident alveolar macrophages was substantial in both mouse strains, particularly after chronic exposure, with concurrent increased proinflammatory cytokine expression of CXCL1 and TNFα in the bronchial lavage fluid. In the acute exposure paradigm, only UFP and UFP + G induced significant changes in pulmonary inflammation and only in the ApoE^−/− animals. Similarly, acute exposure to UFP and UFP + G increased the expression of several cytokines in the hippocampus of ApoE^−/− mice including Il-1β, IL-6, Tgf-β and Tnf-α and in the hippocampus of C57BL/6 mice including Ccl5, Cxcl1, Il-1β, and Tnf-α. Interestingly, Il-6 and Tgf-β expression were decreased in the C57BL/6 hippocampus after acute exposure. Chronic exposure to UFP + G increased expression of Ccl5, Cxcl1, Il-6, and Tgf-β in the ApoE^−/− hippocampus, but this effect was minimal in the C57BL/6 mice, suggesting compensatory mechanisms to manage neuroinflammation in this strain.

Conclusions

Inflammatory responses the lung and brain were most substantial in ApoE^−/− animals exposed to UFP + G, suggesting that the surface area-dependent interaction of gases and particles is an important determinant of toxic responses. As such, freshly generated UFP, in the presence of combustion-derived gas phase pollutants, may be a greater health hazard than would be predicted from PM concentration, alone, lending support for epidemiological findings of adverse neurological outcomes associated with roadway proximity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-016-0177-x) contains supplementary material, which is available to authorized users.

Serum from obstructive sleep apnea patients induces inflammatory responses in coronary artery endothelial cells

BACKGROUND AND AIMS

Obstructive sleep apnea (OSA) is characterized by intermittent airway obstruction and systemic hypoxia during sleep, which can contribute to an increase in reactive oxygen species, vascular remodeling, vasoconstriction and ultimately cardiovascular disease. Continuous positive airway pressure (CPAP) is a clinical therapy that maintains airway patency and mitigates several symptoms of OSA. However, it is currently unknown whether CPAP therapy also reduces the overall inflammatory potential in the circulation; to address this in an unbiased manner, we applied a novel endothelial biosensor approach, the serum cumulative inflammatory potential (SCIP) assay.

METHODS

We studied healthy controls (n = 7), OSA subjects receiving no treatment, (OSA controls) (n = 7) and OSA subjects receiving CPAP for 3 months (n = 8). Serum was obtained from OSA subjects before and after CPAP or no treatment. A battery of quantitative and functional assays was performed to assess the serum inflammatory potential, in terms of endothelial responses. For the SCIP assay, human coronary artery endothelial cells (hCAECs) were incubated with 5% serum in media from individual subjects for 4 h. qPCR was performed to assess endothelial inflammatory transcript (ICAM-1, VCAM-1, IL-8, P-selectin, CCL5, and CXCL12) responses to serum. Additionally, transendothelial resistance was measured in serum-incubated hCAECs following leukocyte challenge.

RESULTS

hCAECs exhibited significant increases in VCAM-1, ICAM-1, IL-8 and P-selectin mRNA when incubated with serum from OSA patients compared to serum from healthy control subjects. Furthermore, compared to no treatment, serum from CPAP-treated individuals was less potent at inducing inflammatory gene expression in the SCIP assay. Similarly, in a leukocyte adhesion assay, naïve cells treated with serum from patients who received CPAP exhibited improved endothelial barrier function than cells treated with OSA control serum.

CONCLUSIONS

OSA results in greater serum inflammatory potential, thereby driving endothelial activation and dysfunction.

Hypoxia-induced pulmonary arterial hypertension augments lung injury and airway reactivity caused by ozone exposure

Ozone (O3)-related cardiorespiratory effects are a growing public health concern. Ground level O3 can exacerbate pre-existing respiratory conditions; however, research regarding therapeutic interventions to reduce O3-induced lung injury is limited. In patients with chronic obstructive pulmonary disease, hypoxia-associated pulmonary hypertension (HPH) is a frequent comorbidity that is difficult to treat clinically, yet associated with increased mortality and frequency of exacerbations. In this study, we hypothesized that established HPH would confer vulnerability to acute O3 pulmonary toxicity. Additionally, we tested whether improvement of pulmonary endothelial barrier integrity via rho-kinase inhibition could mitigate pulmonary inflammation and injury. To determine if O3 exacerbated HPH, male C57BL/6 mice were subject to either 3 weeks continuous normoxia (20.9% O2) or hypoxia (10.0% O2), followed by a 4-h exposure to either 1ppm O3 or filtered air (FA). As an additional experimental intervention fasudil (20mg/kg) was administered intraperitoneally prior to and after O3 exposures. As expected, hypoxia significantly increased right ventricular pressure and hypertrophy. O3 exposure in normoxic mice caused lung inflammation but not injury, as indicated by increased cellularity and edema in the lung. However, in hypoxic mice, O3 exposure led to increased inflammation and edema, along with a profound increase in airway hyperresponsiveness to methacholine. Fasudil administration resulted in reduced O3-induced lung injury via the enhancement of pulmonary endothelial barrier integrity. These results indicate that increased pulmonary vascular pressure may enhance lung injury, inflammation and edema when exposed to pollutants, and that enhancement of pulmonary endothelial barrier integrity may alleviate such vulnerability.

Microglial priming through the lung-brain axis: the role of air pollution-induced circulating factors

Air pollution is implicated in neurodegenerative disease risk and progression and in microglial activation, but the mechanisms are unknown. In this study, microglia remained activated 24 h after ozone (O3) exposure in rats, suggesting a persistent signal from lung to brain. Ex vivo analysis of serum from O3-treated rats revealed an augmented microglial proinflammatory response and β-amyloid 42 (Aβ42) neurotoxicity independent of traditional circulating cytokines, where macrophage-1 antigen-mediated microglia proinflammatory priming. Aged mice exhibited reduced pulmonary immune profiles and the most pronounced neuroinflammation and microglial activation in response to mixed vehicle emissions. Consistent with this premise, cluster of differentiation 36 (CD36)(-/-) mice exhibited impaired pulmonary immune responses concurrent with augmented neuroinflammation and microglial activation in response to O3 Further, aging glia were more sensitive to the proinflammatory effects of O3 serum. Together, these findings outline the lung-brain axis, where air pollutant exposures result in circulating, cytokine-independent signals present in serum that elevate the brain proinflammatory milieu, which is linked to the pulmonary response and is further augmented with age.-Mumaw, C. L., Levesque, S., McGraw, C., Robertson, S., Lucas, S., Stafflinger, J. E., Campen, M. J., Hall, P., Norenberg, J. P., Anderson, T., Lund, A. K., McDonald, J. D., Ottens, A. K., Block, M. L. Microglial priming through the lung-brain axis: the role of air pollution-induced circulating factors.

MMP-9-Dependent Serum-Borne Bioactivity Caused by Multiwalled Carbon Nanotube Exposure Induces Vascular Dysfunction via the CD36 Scavenger Receptor

Inhalation of multiwalled carbon nanotubes (MWCNT) causes systemic effects including vascular inflammation, endothelial dysfunction, and acute phase protein expression. MWCNTs translocate only minimally beyond the lungs, thus cardiovascular effects thereof may be caused by generation of secondary biomolecular factors from MWCNT-pulmonary interactions that spill over into the systemic circulation. Therefore, we hypothesized that induced matrix metalloproteinase-9 (MMP-9) is a generator of factors that, in turn, drive vascular effects through ligand-receptor interactions with the multiligand pattern recognition receptor, CD36. To test this, wildtype (WT; C57BL/6) and MMP-9(-/-)mice were exposed to varying doses (10 or 40 µg) of MWCNTs via oropharyngeal aspiration and serum was collected at 4 and 24 h postexposure. Endothelial cells treated with serum from MWCNT-exposed WT mice exhibited significantly reduced nitric oxide (NO) generation, as measured by electron paramagnetic resonance, an effect that was independent of NO scavenging. Serum from MWCNT-exposed WT mice inhibited acetylcholine (ACh)-mediated relaxation of aortic rings at both time points. Absence of CD36 on the aortic rings (obtained from CD36-deficient mice) abolished the serum-induced impairment of vasorelaxation. MWCNT exposure induced MMP-9 protein levels in both bronchoalveolar lavage and whole lung lysates. Serum from MMP-9(-/-)mice exposed to MWCNT did not diminish the magnitude of vasorelaxation in naïve WT aortic rings, although a modest right shift of the ACh dose-response curve was observed in both MWCNT dose groups relative to controls. In conclusion, pulmonary exposure to MWCNT leads to elevated MMP-9 levels and MMP-9-dependent generation of circulating bioactive factors that promote endothelial dysfunction and decreased NO bioavailability via interaction with vascular CD36.

Metabolomic changes in murine serum following inhalation exposure to gasoline and diesel engine emissions

The adverse health effects of environmental exposure to gaseous and particulate components of vehicular emissions are a major concern among urban populations. A link has been established between respiratory exposure to vehicular emissions and the development of cardiovascular disease (CVD), but the mechanisms driving this interaction remain unknown. Chronic inhalation exposure to mixed vehicle emissions has been linked to CVD in animal models. This study evaluated the temporal effects of acute exposure to mixed vehicle emissions (MVE; mixed gasoline and diesel emissions) on potentially active metabolites in the serum of exposed mice. C57Bl/6 mice were exposed to a single 6-hour exposure to filtered air (FA) or MVE (100 or 300 μg/m(3)) by whole body inhalation. Immediately after and 18 hours after the end of the exposure period, animals were sacrificed for serum and tissue collection. Serum was analyzed for metabolites that were differentially present between treatment groups and time points. Changes in metabolite levels suggestive of increased oxidative stress (oxidized glutathione, cysteine disulfide, taurine), lipid peroxidation (13-HODE, 9-HODE), energy metabolism (lactate, glycerate, branched chain amino acid catabolites, butrylcarnitine, fatty acids), and inflammation (DiHOME, palmitoyl ethanolamide) were observed immediately after the end of exposure in the serum of animals exposed to MVE relative to those exposed to FA. By 18 hours post exposure, serum metabolite differences between animals exposed to MVE versus those exposed to FA were less pronounced. These findings highlight complex metabolomics alterations in the circulation following inhalation exposure to a common source of combustion emissions.

Associations of Circulating Oxidized LDL and Conventional Biomarkers of Cardiovascular Disease in a Cross-Sectional Study of the Navajo Population

The prevalences of cardiovascular disease (CVD) and type 2 diabetes (T2D) have increased among the Navajo Native American community in recent decades. Oxidized low-density lipoprotein (oxLDL) is a novel CVD biomarker that has never been assessed in the Navajo population. We examined the relationship of oxLDL to conventional CVD and T2D risk factors and biomarkers in a cross-sectional population of Navajo participants. This cross-sectional study included 252 participants from 20 Navajo communities from the Diné Network for Environmental Health Project. Plasma samples were tested for oxLDL levels by a sandwich enzyme-linked immunosorbent assay. Univariate and multivariate analyses were used to determine the relationship of oxLDL and oxidized- to non-oxidized lipoprotein ratios to glycated hemoglobin (HbA1c), C-reactive protein (CRP), interleukin 6 (IL6) and demographic and health variables. Type 2 diabetes, hypertension and obesity are very prevalent in this Navajo population. HbA1c, CRP, body mass index (BMI), high-density lipoprotein, and triglycerides were at levels that may increase risk for CVD and T2D. Median oxLDL level was 47 (36.8–57) U/L. Correlational analysis showed that although oxLDL alone was not associated with HbA1c, oxLDL/HDL, oxLDL/LDL and CRP were significantly associated with HbA1c and glucose. OxLDL, oxLDL/HDL and oxLDL/LDL were significantly associated with CRP. Multivariate analysis showed that triglycerides were a common and strong predictor of oxLDL, oxLDL/HDL and oxLDL/LDL. OxLDL was trended with HbA1c and glucose but did not reach significance, however, HbA1c was an independent predictor of OxLDL/HDL. CRP trended with oxLDL/HDL and was a weak predictor of oxLDL/LDL. This Navajo subset appears to have oxLDL levels comparable to subjects without evidence of CVD reported in other studies. The high prevalence of T2D, hypertension and obesity along with abnormal levels of other biomarkers including HbA1c indicate that the Navajo population has a worsening CVD risk profile.

Ozone Inhalation Impairs Coronary Artery Dilation via Intracellular Oxidative Stress: Evidence for Serum-Borne Factors as Drivers of Systemic Toxicity

Ambient ozone (O3) levels are associated with cardiovascular morbidity and mortality, but the underlying pathophysiological mechanisms driving extrapulmonary toxicity remain unclear. This study examined the coronary vascular bed of rats in terms of constrictive and dilatory responses to known agonists following a single O3 inhalation exposure. In addition, serum from exposed rats was used in ex vivo preparations to examine whether bioactivity and toxic effects of inhaled O3 could be conveyed to extrapulmonary systems via the circulation. We found that 24 h following inhalation of 1 ppm O3, isolated coronary vessels exhibited greater basal tone and constricted to a greater degree to serotonin stimulation. Vasodilation to acetylcholine (ACh) was markedly diminished in coronary arteries from O3-exposed rats, compared with filtered air-exposed controls. Dilation to ACh was restored by combined superoxide dismutase and catalase treatment, and also by NADPH oxidase inhibition. When dilute (10%) serum from exposed rats was perfused into the lumen of coronary arteries from unexposed, naïve rats, the O3-induced reduction in vasodilatory response to ACh was partially recapitulated. Furthermore, following O3 inhalation, serum exhibited a nitric oxide scavenging capacity, which may partially explain blunted ACh-mediated vasodilatory responses. Thus, bioactivity from inhalation exposures may be due to compositional changes of the circulation. These studies shed light on possible mechanisms of action that may explain O3-associated cardiac morbidity and mortality in humans.

The National Environmental Respiratory Center (NERC) experiment in multi-pollutant air quality health research: II. Comparison of responses to diesel and gasoline engine exhausts, hardwood smoke and simulated downwind coal emissions

The NERC Program conducted identically designed exposure-response studies of the respiratory and cardiovascular responses of rodents exposed by inhalation for up to 6 months to diesel and gasoline exhausts (DE, GE), wood smoke (WS) and simulated downwind coal emissions (CE). Concentrations of the four combustion-derived mixtures ranged from near upper bound plausible to common occupational and environmental hotspot levels. An "exposure effect" statistic was created to compare the strengths of exposure-response relationships and adjustments were made to minimize false positives among the large number of comparisons. All four exposures caused statistically significant effects. No exposure caused overt illness, neutrophilic lung inflammation, increased circulating micronuclei or histopathology of major organs visible by light microscopy. DE and GE caused the greatest lung cytotoxicity. WS elicited the most responses in lung lavage fluid. All exposures reduced oxidant production by unstimulated alveolar macrophages, but only GE suppressed stimulated macrophages. Only DE retarded clearance of bacteria from the lung. DE before antigen challenge suppressed responses of allergic mice. CE tended to amplify allergic responses regardless of exposure order. GE and DE induced oxidant stress and pro-atherosclerotic responses in aorta; WS and CE had no such effects. No overall ranking of toxicity was plausible. The ranking of exposures by number of significant responses varied among the response models, with each of the four causing the most responses for at least one model. Each exposure could also be deemed most or least toxic depending on the exposure metric used for comparison. The database is available for additional analyses.

Characterization of a novel endothelial biosensor assay reveals increased cumulative serum inflammatory potential in stabilized coronary artery disease patients

Background

Vascular disease is promoted by systemic inflammation that can arise from sites distal to the affected vessels. We sought to characterize the net inflammatory potential of serum from patients with coronary artery disease (CAD) using cultured endothelial cells as a cumulative biosensor.

Methods and results

Serum samples from CAD patients (N = 45) and healthy control subjects (N = 48) were incubated with primary human coronary artery endothelial cells at a 1:10 dilution for 4 h, followed by isolation of the cellular RNA. Alteration of inflammation-responsive elements (adhesion molecules and cytokines) was assessed by gene expression. Specific indicators included intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and interleukin-8 (IL-8). Additionally, the cytokine levels in serum samples from all subjects were quantified. Serum from CAD subjects induced greater endothelial ICAM-1, VCAM-1, and IL-8 expression compared to healthy control serum (p < 0.001 for each analysis). The three indicators of inflammatory potential (ICAM-1, VCAM-1, and IL-8 mRNA) trended independently of each other and also of serum inflammatory biomarkers. IL-8 expression correlated negatively with serum HDL levels but positively correlated with VLDL, plasminogen activator inhibitor-1 and C-reactive protein. Interestingly, serum levels of cytokines in CAD patients were not statistically different from healthy control subjects. A year of follow-up in a sub-group of CAD subjects revealed relatively stable measures.

Conclusions

As yet unidentified circulating factors in the serum of CAD patients appear to activate endothelial cells, leading to upregulation of adhesion molecules and chemokines. This cumulative assay performed well in terms of discriminating patients with CAD compared to healthy subjects, with greater range and specificity than specific inflammatory markers.

Effects of nicotine on cardiovascular remodeling in a mouse model of systemic hypertension

Usage of nicotine-only formulations, such as transdermal patches, nicotine gum, or electronic nicotine delivery systems is increasing, as they are perceived as healthier alternatives to traditional cigarettes. Unfortunately, there is little data available on the effect of isolated nicotine on myocardial and aortic remodeling, especially in the setting of cardiovascular disease risk factors, such as hypertension. We hypothesized that nicotine would exacerbate cardiovascular remodeling induced by angiotensin-II (Ang II) treatment. Subcutaneous osmotic minipumps were implanted to administer Ang II, Nic, nicotine plus Ang II or saline to C57Bl/6 mice for 4 weeks. Heart weights were increased by all treatments, with control < nicotine < Ang II < nicotine + Ang II. Activity levels of matrix metalloproteinase-2 mirrored these changes and demonstrated clear additivity between nicotine and Ang II. Histopathological analysis of aortas revealed that mice receiving combined nicotine and Ang II treatment induced significant hypertrophy compared to all other groups. This study reveals possible cardiotoxic interactions between nicotine and a common model of systemic hypertension. Safety testing of novel nicotine delivery devices should consider that hypertension is a common impetus to begin smoking cessation therapy, and potential interactions should be more thoroughly studied.

Muscle RING finger-1 promotes a maladaptive phenotype in chronic hypoxia-induced right ventricular remodeling

Exposure to chronic hypoxia (CH) induces elevated pulmonary artery pressure/resistance, leading to an eventual maladaptive right ventricular hypertrophy (RVH). Muscle RING finger-1 (MuRF1) is a muscle-specific ubiquitin ligase that mediates myocyte atrophy and has been shown to play a role in left ventricular hypertrophy and altered cardiac bioenergetics in pressure overloaded hearts. However, little is known about the contribution of MuRF1 impacting RVH in the setting of CH. Therefore, we hypothesized that MuRF1 deletion would enhance RVH compared to their wild-type littermates, while cardiac-specific overexpression would reduce hypertrophy following CH-induced pulmonary hypertension. We assessed right ventricular systolic pressure (RVSP), right ventricle to left ventricle plus septal weight ratio (RV/LV+S) and hematocrit (Hct) following a 3-wk isobaric CH exposure. Additionally, we conducted dual-isotope SPECT/CT imaging with cardiac function agent ²⁰¹Tl-chloride and cell death agent ^99mTc-annexin V. Predictably, CH induced pulmonary hypertension, measured by increased RVSP, RV/LV+S and Hct in WT mice compared to normoxic WT mice. Normoxic WT and MuRF1-null mice exhibited no significant differences in RVSP, RV/LV+S or Hct. CH-induced increases in RVSP were also similar between WT and MuRF1-null mice; however, RV/LV+S and Hct were significantly elevated in CH-exposed MuRF1-null mice compared to WT. In cardiac-specific MuRF1 overexpressing mice, RV/LV+S increased significantly due to CH exposure, even greater than in WT mice. This remodeling appeared eccentric, maladaptive and led to reduced systemic perfusion. In conclusion, these results are consistent with an atrophic role for MuRF1 regulating the magnitude of right ventricular hypertrophy following CH-induction of pulmonary hypertension.

National Particle Component Toxicity (NPACT) initiative report on cardiovascular effects

Epidemiologic and toxicologic studies were carried out in concert to provide complementary insights into the compositional features of ambient particulate matter (PM*) that produce cardiovascular effects. In the epidemiologic studies, we made use of cohort data from two ongoing studies--the Multi-Ethnic Study of Atherosclerosis (MESA) and the Women's Health Initiative--Observational Study (WHI-OS)--to investigate subclinical markers of atherosclerosis and clinical cardiovascular events. In the toxicologic study, we used the apolipoprotein E null (ApoE(-/-)) hypercholesterolemic mouse model to assess cardiovascular effects of inhalation exposure to various atmospheres containing laboratory-generated pollutants. In the epidemiologic studies, individual-level residential concentrations of fine PM, that is, PM with an aerodynamic diameter of 2.5 microm or smaller (PM2.5), PM2.5 components (primarily elemental carbon [EC] and organic carbon [OC], silicon, and sulfur but also sulfate, nitrate, nickel, vanadium, and copper), and the gaseous pollutants sulfur dioxide and nitrogen dioxide were estimated using spatiotemporal modeling and other exposure estimation approaches. In the MESA cohort data, evidence for associations with increased carotid intima-media thickness (CIMT) was found to be strongest for PM2.5, OC, and sulfur, as well as for copper in more limited analyses; the evidence for this was found to be weaker for silicon, EC, and the other components and gases. Similarly, in the WHI-OS cohort data, evidence for associations with incidence of cardiovascular mortality and cardiovascular events was found to be good for OC and sulfur, respectively, and for PM2.5; the evidence for this was found to be weaker for EC and silicon. Source apportionment based on extensive monitoring data in the six cities in the MESA analyses indicated that OC represented secondary formation processes as well as primary gasoline and biomass emissions, that sulfur represented largely secondary inorganic aerosols, and that copper represented brake dust and diesel emissions. In the toxicologic study, hypercholesterolemic mice were exposed for 50 days to atmospheres containing mixed vehicular engine emissions (MVE) consisting of mixed gasoline and diesel engine exhaust or to MVE-derived gases only (MVEG). Mice were also exposed to atmospheres containing sulfate, nitrate, or road dust, either alone or mixed with MVE or MVEG. Sulfate alone or in combination with MVE was associated with increased aortic reactivity. All exposures to atmospheres containing MVE (including a combination of MVE with other PM) were associated with increases in plasma and aortic oxidative stress; exposures to atmospheres containing only sulfate or nitrate were not. Exposure to MVE and to MVEG combinations except those containing road dust resulted in increased monocyte/macrophage sequestration in aortic plaque (a measure of plaque inflammation). Exposure to all atmospheres except those containing nitrate was associated with enhanced aortic vasoconstriction. Exposure to the MVEG was an independent driver of lipid peroxidation, matrix metalloproteinase (MMP) activation, and vascular inflammation. The epidemiologic and toxicologic study designs were intended to complement each other. The epidemiologic studies provided evidence in real-world human settings, and the toxicologic study directly assessed the biologic effects of various pollutant mixtures (in a way that is not possible in epidemiologic studies) by examining endpoints that probably underlie the subclinical and clinical cardiovascular endpoints examined in the epidemiologic studies. The epidemiologic studies were not suited to determining whether the observed associations were caused by direct effects of individual pollutants or by the mixtures in which individual pollutants are found. These studies were consistent in finding that OC and sulfate had the strongest evidence for associations with the cardiovascular disease endpoints, with much weaker evidence for EC and silicon. Both OC and sulfate reflected a large secondary aerosol component. Results from the toxicologic study indicated, for the most part, that MVE and mixtures of MVE and MVEG with other PM pollutants were important in producing the toxic cardiovascular effects found in the study. Further work on the effects of pollutant mixtures and secondary aerosols should allow better understanding of the pollution components and sources most responsible for the adverse cardiovascular effects of air pollution exposure.