Formaldehyde and the Transient Receptor Potential Ankyrin-1 Contribute to Electronic Cigarette Aerosol-induced Endothelial Dysfunction in Mice.

Electronic Nicotine Delivery Systems (ENDS) aerosol exposures can induce endothelial dysfunction (ED) in healthy young humans and animals. Thermal degradation of ENDS solvents, propylene glycol and vegetable glycerin (PG: VG), generates abundant formaldehyde (FA) and other carbonyls. Because FA can activate the transient receptor potential ankyrin-1 (TRPA1) sensor, we hypothesized that FA in ENDS aerosols provokes TRPA1-mediated changes that include ED and 'respiratory braking' - biomarkers of harm. To test this, wild-type (WT) and TRPA1-null mice were exposed by inhalation to either filtered air, PG: VG-derived aerosol, or formaldehyde (FA, 5 ppm). Short-term exposures to PG: VG and FA induced ED in female WT but not in female TRPA1-null mice. Moreover, acute exposures to PG: VG and FA stimulated respiratory braking in WT but not in TRPA1-null female mice. Urinary metabolites of FA (ie, N  -1,3-thiazolidine-4-carboxylic acid, TCA; N  -1,3-thiazolidine-4-carbonyl glycine, TCG) and monoamines were measured by LC-MS/MS. PG: VG and FA exposures significantly increased urinary excretion of both TCA and TCG in both WT and TRPA1-null mice. To confirm that inhaled FA directly contributed to urinary TCA, mice were exposed to isotopic 13C-FA gas (1 ppm, 6 h).13C-FA exposure significantly increased the urine level of 13C-TCA in the early collection (0-3 h) supporting a direct relationship between inhaled FA and TCA. Collectively, these data suggest that ENDS use may increase CVD risk dependent on FA, TRPA1, and catecholamines, yet independently of either nicotine or flavorants. This study supports that levels of FA in ENDS-derived aerosols should be lowered to mitigate CVD risk in people who use ENDS.

Urinary Volatile Organic Compound Metabolites are Associated with High Blood Pressure Among Non-smoking Participants in the National Health and Nutrition Examination Survey (2011-2018).

Background: Volatile organic compounds (VOCs) are ubiquitous environmental pollutants. Exposure to VOCs is associated with cardiovascular disease (CVD) risk factors, including elevated blood pressure (BP) in susceptible populations. However, research in the general population, particularly among non-smoking adults, is limited. We hypothesized that higher VOC exposure is associated with higher BP and hypertension, among non-smokers. Methods: We included four cycles of data (2011-2018) of non-smoking adults (n=4,430) from the National Health and Nutrition Examination Survey (NHANES). Urinary VOC metabolites were measured by ultra-performance liquid chromatography-mass spectrometry, adjusted for urine dilution, and log-transformed. We estimated mean differences in BP using linear models and prevalence ratio of stage 2 hypertension using modified Poisson models with robust standard errors. Models were adjusted for age, sex, race and ethnicity, education, body mass index, estimated glomerular filtration rate and NHANES cycle. Results: Participants were 54% female, with a median age of 48 years, 32.3% had hypertension, and 7.9% had diabetes. The mean differences (95% CI) in systolic BP were 1.61 (0.07, 3.15) and 2.46 (1.01, 3.92) mmHg when comparing the highest to lowest quartile of urinary acrolein (CEMA) and 1,3-butadiene (DHBMA) metabolites. The prevalence ratios (PR) for hypertension were 1.06 (1.02, 1.09) and 1.05 (1.01, 1.09) when comparing the highest to lowest quartiles of urinary acrolein (CEMA) and 1,3-butadiene (DHBMA), respectively. Conclusions: Exposure to VOCs may be relevant yet understudied environmental contributors to CVD risk in the non-smoking, US population.

Intra-neighborhood associations between residential greenness and blood pressure.

INTRODUCTION: Previous investigations have reported that individuals living in greener neighborhoods have better cardiovascular health. It is unclear whether the effects reported at large geographic scales persist when examined at an intra-neighborhood level. The effects of greenness have not been thoroughly examined using high-resolution metrics of greenness exposure, and how they vary with spatial scales of assessment or participant characteristics. METHODS: We conducted a cross-sectional assessment of associations between blood pressure and multiple high-resolution measures of residential area greenness in spatially concentrated HEAL Study cohort of the Green Heart Project. We employed generalized linear models, accounting for individual-level covariates, to examine associations between different high-resolution measures of greenness and blood pressure among 667 participants in a 4 sq. mile contiguous neighborhood area in Louisville, KY. RESULTS: In adjusted models, we observed significant inverse associations between residential greenness, measured by leaf area index (LAI), and systolic blood pressure (SBP) within 150-250 m and 500 m of homes, but not for Normalized Difference Vegetation Index (NDVI) or grass cover. Weaker associations were also found with diastolic blood pressure (DBP). Significant positive associations were observed between LAI and SBP among participants who reported being female, White, without obesity, non-exercisers, non-smokers, younger age, of lower income, and who had high nearby roadway traffic. We found few significant associations between grass cover and SBP, but an inverse association in those with obesity, but positive associations for those without obesity. CONCLUSIONS: We found that leaf surface area of trees around participants home is strongly associated with lower blood pressure, with little association with grass cover. These effects varied with participant characteristics and spatial scales. More research is needed to test causative links between greenspace types and cardiovascular health and to develop population-, typology-, and place-based evidence to inform greening interventions.

Long-term exposure to air pollution and risk of stroke by ecoregions: The REGARDS study.

Several cohort studies have found associations between long-term exposure to air pollution and stroke risk. However, it is unclear whether the surrounding ecology may modify these associations. This study evaluates associations of air pollution with stroke risk by ecoregions, which are areas of similar type, quality, and quantity of environmental resources in the REasons for Geographic and Racial Differences in Stroke (REGARDS) study. We assessed the incidence of stroke in 26,792 participants (45+ yrs) from the REGARDS study, a prospective cohort recruited across the contiguous United States. One-yr and 3-yr means of PM2.5, PM10, O3, NO2, SO2, and CO were estimated at baseline using data from the Center for Air, Climate, & Energy Solution, and assigned to participants at the census block group level. Incident stroke was ascertained through September 30, 2020. Relations of air pollutants with the risk of incident stroke were estimated using Cox proportional hazards models, adjusting for relevant demographics, behavioral risk factors, and neighborhood urbanicity. Models were stratified by EPA designated ecoregions. A 5.4 µg/m3 (interquartile range) increase in 1-yr PM10 was associated with a hazard ratio (95 %CI) for incident stroke of 1.07 (1.003, 1.15) in the overall study population. We did not find evidence of positive associations for PM2.5, O3, NO2, SO2, and CO in the fully adjusted models. In our ecoregion-specific analysis, associations of PM2.5 with stroke were stronger in the Great Plains ecoregion (HR = 1.44) than other ecoregions, while associations for PM10 were strongest in the Eastern Temperate Forests region (HR = 1.15). The associations between long-term exposure to air pollution and risk of stroke varied by ecoregion. Our results suggests that the type, quality, and quantity of the surrounding ecology can modify the effects of air pollution on risk of stroke.

Smoking-associated Electrocardiographic Abnormalities Predict Cardiovascular Mortality: Insights from NHANES.

Background­: Smoking is associated with arrhythmia and sudden cardiac death, but the biological mechanisms remain unclear. Abnormal electrocardiogram (ECG) durations of ventricular repolarization (QT interval), atrial depolarization (P wave), and atrioventricular depolarization (PR interval and segment), predict cardiac arrhythmia and mortality. Objectives­: To elucidate how smoking affects cardiac excitation, we assessed in a nationally representative sample (NHANES III) associations between cotinine, abnormalities in P duration, PR interval, PR segment, rate-corrected QT (QTc), QRS duration, and JT interval, and long-term mortality. Methods­: We analyzed data from 5,633 adults using survey-weighted multinomial logistic regression to estimate associations between tobacco use (>15 ng/ml serum cotinine) and short (<5th percentile) or long (>95th percentile) ECG intervals, relative to reference (5 - 95th percentile). Results­: After adjustment for demographics, risk factors, and conduction-altering medications, smoking was associated with a higher odds of short PR interval, PR segment, and QRS, and long JT. Broader ECG effects of smoking were also assessed by survey-weighted linear regression of continuous cotinine and ECG intervals, which revealed cotinine inversely associated with PR segment and QTc. Over a 22-year follow-up, many ECG abnormalities predicted cardiovascular mortality in smokers, including long JT, QRS, and QTc, and short QRS. Conclusions­: Smoking increases likelihood for rapid atrioventricular conduction, rapid ventricular depolarization, and slow ventricular repolarization. The ventricular electrophysiologic abnormalities associated with smoking also predict cardiovascular mortality in smokers; however, traditional ECG measures of cardiac risk like QTc can overlook these ventricular defects and their independent predictive value in smokers.

Transcriptional Heterogeneity Overcomes Super-Enhancer Disrupting Drug Combinations in Multiple Myeloma.

Multiple myeloma (MM) is a malignancy that is often driven by MYC and that is sustained by IRF4, which are upregulated by super-enhancers. IKZF1 and IKZF3 bind to super-enhancers and can be degraded using immunomodulatory imide drugs (IMiD). Successful IMiD responses downregulate MYC and IRF4; however, this fails in IMiD-resistant cells. MYC and IRF4 downregulation can also be achieved in IMiD-resistant tumors using inhibitors of BET and EP300 transcriptional coactivator proteins; however, in vivo these drugs have a narrow therapeutic window. By combining IMiDs with EP300 inhibition, we demonstrate greater downregulation of MYC and IRF4, synergistic killing of myeloma in vitro and in vivo, and an increased therapeutic window. Interestingly, this potent combination failed where MYC and IRF4 expression was maintained by high levels of the AP-1 factor BATF. Our results identify an effective drug combination and a previously unrecognized mechanism of IMiD resistance. SIGNIFICANCE: These results highlight the dependence of MM on IKZF1-bound super-enhancers, which can be effectively targeted by a potent therapeutic combination pairing IMiD-mediated degradation of IKZF1 and IKZF3 with EP300 inhibition. They also identify AP-1 factors as an unrecognized mechanism of IMiD resistance in MM. See related article by Neri, Barwick, et al., p. 56. See related commentary by Yun and Cleveland, p. 5. This article is featured in Selected Articles from This Issue, p. 4.

ETV4-Dependent Transcriptional Plasticity Maintains MYC Expression and Results in IMiD Resistance in Multiple Myeloma.

Immunomodulatory drugs (IMiD) are a backbone therapy for multiple myeloma (MM). Despite their efficacy, most patients develop resistance, and the mechanisms are not fully defined. Here, we show that IMiD responses are directed by IMiD-dependent degradation of IKZF1 and IKZF3 that bind to enhancers necessary to sustain the expression of MYC and other myeloma oncogenes. IMiD treatment universally depleted chromatin-bound IKZF1, but eviction of P300 and BRD4 coactivators only occurred in IMiD-sensitive cells. IKZF1-bound enhancers overlapped other transcription factor binding motifs, including ETV4. Chromatin immunoprecipitation sequencing showed that ETV4 bound to the same enhancers as IKZF1, and ETV4 CRISPR/Cas9-mediated ablation resulted in sensitization of IMiD-resistant MM. ETV4 expression is associated with IMiD resistance in cell lines, poor prognosis in patients, and is upregulated at relapse. These data indicate that ETV4 alleviates IKZF1 and IKZF3 dependency in MM by maintaining oncogenic enhancer activity and identify transcriptional plasticity as a previously unrecognized mechanism of IMiD resistance. SIGNIFICANCE: We show that IKZF1-bound enhancers are critical for IMiD efficacy and that the factor ETV4 can bind the same enhancers and substitute for IKZF1 and mediate IMiD resistance by maintaining MYC and other oncogenes. These data implicate transcription factor redundancy as a previously unrecognized mode of IMiD resistance in MM. See related article by Welsh, Barwick, et al., p. 34. See related commentary by Yun and Cleveland, p. 5. This article is featured in Selected Articles from This Issue, p. 4.

Anti-inflammatory mechanisms in cancer research: Characterization of a distinct M2-like macrophage model derived from the THP-1 cell line.

AIMS: Macrophages play an essential role in cancer development. Tumor-associated macrophages (TAMs) have predominantly M2-like attributes that are associated with tumor progression and poor patient survival. Numerous methods have been reported for differentiating and polarizing macrophages in vitro, but there is no standardized and validated model for creating TAMs. Primary cells show varying cytokine responses depending on their origin and functional studies utilizing these cells may lack generalization and validity. A distinct cell line-derived TAM-like M2 subtype is required to investigate the mechanisms mediated by anti-inflammatory TAMs in vitro. Our previous work demonstrated a standardized protocol for creating an M2 subtype derived from a human THP-1 cell line. The cell expression profile, however, has not been validated. The aim of this study was to characterize and validate the TAM-like M2 subtype macrophage created based on our protocol to introduce them as a standardized model for cancer research. METHODS AND RESULTS: Using qRT-PCR and ELISA, we demonstrated that proinflammatory, anti-inflammatory, and tumor-associated marker expression changed during THP-1-derived marcrophage development in vitro, mimicking a TAM-related profile (e.g., TNFα, IL-1ß). The anti-inflammatory marker IL-8/CXCL8, however, is most highly expressed in young M0 macrophages. Flow cytometry showed increased expression of CD206 in the final TAM-like M2 macrophage. Single-cell RNA-sequencing analysis of primary human monocytes and colon cancer tissue macrophages demonstrated that cell line-derived M2 macrophages resembled a TAM-related gene profile. CONCLUSIONS: The THP-1-derived M2 macrophage based on a standardized cell line model represents a distinct anti-inflammatory TAM-like phenotype with an M2a subtype profile. This model may provide a basis for in vitro investigation of functional mechanisms in a variety of anti-inflammatory settings, particularly colon cancer development.

The Green Heart Project: Objectives, Design, and Methods.

The Green Heart Project is a community-based trial to evaluate the effects of increasing greenery on urban environment and community health. The study was initiated in 2018 in a low-to-middle-income mixed-race residential area of nearly 28,000 residents in Louisville, KY. The 4 square mile area was surveyed for land use, population characteristics, and greenness, and assigned to 8 paired clusters of demographically- and environmentally matched "target" (T) and adjacent "control" (C), clusters. Ambient levels of ultrafine particles, ozone, oxides of nitrogen, and environmental noise were measured in each cluster. Individual-level data were acquired during in-person exams of 735 participants in Wave 1 (2018-2019) and 545 participants in Wave 2 (2021) to evaluate sociodemographic and psychosocial factors. Blood, urine, nail, and hair samples were collected to evaluate standard cardiovascular risk factors, inflammation, stress, and pollutant exposure. Cardiovascular function was assessed by measuring arterial stiffness and flow-mediated dilation. After completion of Wave 2, more than 8,000 mature, mostly evergreen, trees and shrubs were planted in the T clusters in 2022. Post planting environmental and individual-level data were collected during Wave 3 (2022) from 561 participants. We plan to continue following changes in area characteristics and participant health to evaluate the long-term impact of increasing urban greenery.

Greenness and equity: Complex connections between intra-neighborhood contexts and residential tree planting implementation.

Associations between neighborhood greenness and socioeconomic status (SES) are established, yet intra-neighborhood context and SES-related barriers to tree planting remain unclear. Large-scale tree planting implementation efforts are increasingly common and can improve human health, strengthen climate adaptation, and ameliorate environmental inequities. Yet, these efforts may be ineffective without in-depth understanding of local SES inequities and barriers to residential planting. We recruited 636 residents within and surrounding the Oakdale Neighborhood of Louisville, Kentucky, USA, and evaluated associations of individual and neighborhood-level sociodemographic indicators with greenness levels at multiple scales. We offered no-cost residential tree planting and maintenance to residents within a subsection of the neighborhood and examined associations of these sociodemographic indicators plus baseline greenness levels with tree planting adoption among 215 eligible participants. We observed positive associations of income with Normalized Difference Vegetation Index (NDVI) and leaf area index (LAI) within all radii around homes, and within yards of residents, that varied in strength. There were stronger associations of income with NDVI in front yards but LAI in back yards. Among Participants of Color, associations between income and NDVI were stronger than with Whites and exhibited no association with LAI. Tree planting uptake was not associated with income, education, race, nor employment status, but was positively associated with lot size, home value, lower population density, and area greenness. Our findings reveal significant complexity of intra-neighborhood associations between SES and greenness that could help shape future research and equitable greening implementation. Results show that previously documented links between SES and greenspace at large scales extend to residents' yards, highlighting opportunities to redress greenness inequities on private property. Our analysis found that uptake of no-cost residential planting and maintenance was nearly equal across SES groups but did not redress greenness inequity. To inform equitable greening, further research is needed to evaluate culture, norms, perceptions, and values affecting tree planting acceptance among low-SES residents.

Exposure to Volatile Organic Compounds Is Associated with Hypertension in Black Adults: The Jackson Heart Study.

BACKGROUND: The prevalence of hypertension is higher among Black adults than among White and Hispanic adults. Nevertheless, reasons underlying the higher rates of hypertension in the Black population remain unclear but may relate to exposure to environmental chemicals such as volatile organic compounds (VOCs). METHODS: We evaluated the associations of blood pressure (BP) and hypertension with VOC exposure in non-smokers and smokers in a subgroup of the Jackson Heart Study (JHS), consisting of 778 never smokers and 416 age- and sex-matched current smokers. We measured urinary metabolites of 17 VOCs by mass spectrometry. RESULTS: After adjusting for covariates, we found that amoong non-smokers, metabolites of acrolein and crotonaldehyde were associated with a 1.6 mm Hg (95%CI: 0.4, 2.7; p = 0.007) and a 0.8 mm Hg (95%CI: 0.01, 1.6; p = 0.049) higher systolic BP, and the styrene metabolite was associated with a 0.4 mm Hg (95%CI: 0.09, 0.8, p = 0.02) higher diastolic BP. Current smokers had 2.8 mm Hg (95% CI 0.5, 5.1) higher systolic BP. They were at higher risk of hypertension (relative risk = 1.2; 95% CI, 1.1, 1.4), and had higher urinary levels of several VOC metabolites. Individuals who smoke had higher levels of the urinary metabolites of acrolein, 1,3-butadiene, and crotonaldehyde and were associated with higher systolic BP. The associations were stronger among participants who were <60 years of age and male. Using Bayesian kernel machine regression to assess the effects of multiple VOC exposures, we found that the relationship between VOCs and hypertension among non-smokers was driven primarily by acrolein and styrene in non-smokers, and crotonaldehyde in smokers. CONCLUSIONS: Hypertension in Black individuals may be attributed, in part, to VOC exposure from the environment or tobacco smoke.

The Relationship between Perceptions and Objective Measures of Greenness.

Exposure to greenness has been studied through objective measures of remote visualization of greenspace; however, the link to how individuals interpret spaces as green is missing. We examined the associations between three objective greenspace measures with perceptions of greenness. We used a subsample (n = 175; 2018-2019) from an environmental cardiovascular risk cohort to investigate perceptions of residential greenness. Participants completed a 17-item survey electronically. Objective measurements of greenness within 300 m buffer around participants home included normalized difference vegetation index (NDVI), tree canopy and leaf area index. Principal component analysis reduced the perceived greenspaces to three dimensions reflecting natural vegetation, tree cover and built greenspace such as parks. Our results suggest significant positive associations between NDVI, tree canopy and leaf area and perceived greenness reflecting playgrounds; also, associations between tree canopy and perceived greenness reflecting tree cover. These findings indicate that the most used objective greenness measure, NDVI, as well as tree canopy and leaf area may most align with perceptions of parks, whereas tree canopy alone captures individuals' perceptions of tree cover. This highlights the need for research to understand the complexity of green metrics and careful interpretation of data based on the use of subjective or objective measures of greenness.

Community-Based Evaluation of the Associations Between Well-Being and Cardiovascular Disease Risk.

Background Although the effects of psychological health and optimism have been extensively investigated, data from community-based cohorts assessing the association between psychological health and cardiovascular disease risk factors are sparse, and the concurrent relationship between subjective well-being and cardiovascular health has not been studied. Methods and Results The current cross-sectional study examined the association between well-being and cardiovascular risk factors among 719 individuals living in a middle- to low-income neighborhood. After adjusting for age, sex, race, body mass index, education, smoking status, and exercise status, we found that higher levels of well-being were significantly associated with lower odds of dyslipidemia (odds ratio [OR], 0.7 [95% CI, 0.55-0.85]) and hypertension (OR, 0.8 [95% CI, 0.63-0.92]). Greater well-being was also significantly associated with lower triglyceride levels (mean difference [Mdiff], 7.6 [-14.31 to -0.78]), very low-density lipoprotein (Mdiff, 0.9 [-1.71 to -0.16]), total cholesterol to high-density lipoprotein ratio (Mdiff, 3.9 [-6.07 to -1.73]), higher high-density lipoprotein levels (Mdiff, 1.6 [0.46-2.75]), and lower Framingham Risk Scores (Mdiff, -7.1% [-10.84% to -3.16%]). Well-being also moderated the association between age and arterial stiffness. The strongest association between arterial stiffness and age was found for those with the lowest well-being scores; there was no association between age and arterial stiffness at high levels of well-being. Conclusions In a community-based cohort, individuals reporting higher levels of well-being have lower odds of hypertension and dyslipidemia as well as lower rates of age-dependent increase in vascular stiffness. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03670524.

E-cigarettes and their lone constituents induce cardiac arrhythmia and conduction defects in mice.

E-cigarette use has surged, but the long-term health effects remain unknown. E-cigarette aerosols containing nicotine and acrolein, a combustion and e-cigarette byproduct, may impair cardiac electrophysiology through autonomic imbalance. Here we show in mouse electrocardiograms that acute inhalation of e-cigarette aerosols disturbs cardiac conduction, in part through parasympathetic modulation. We demonstrate that, similar to acrolein or combustible cigarette smoke, aerosols from e-cigarette solvents (vegetable glycerin and propylene glycol) induce bradycardia, bradyarrhythmias, and elevations in heart rate variability during inhalation exposure, with inverse post-exposure effects. These effects are slighter with tobacco- or menthol-flavored aerosols containing nicotine, and in female mice. Yet, menthol-flavored and PG aerosols also increase ventricular arrhythmias and augment early ventricular repolarization (J amplitude), while menthol uniquely alters atrial and atrioventricular conduction. Exposure to e-cigarette aerosols from vegetable glycerin and its byproduct, acrolein, diminish heart rate and early repolarization. The pro-arrhythmic effects of solvent aerosols on ventricular repolarization and heart rate variability depend partly on parasympathetic modulation, whereas ventricular arrhythmias positively associate with early repolarization dependent on the presence of nicotine. Our study indicates that chemical constituents of e-cigarettes could contribute to cardiac risk by provoking pro-arrhythmic changes and stimulating autonomic reflexes.

Pyridine nucleotide redox potential in coronary smooth muscle couples myocardial blood flow to cardiac metabolism.

Adequate oxygen delivery to the heart during stress is essential for sustaining cardiac function. Acute increases in myocardial oxygen demand evoke coronary vasodilation and enhance perfusion via functional upregulation of smooth muscle voltage-gated K+ (Kv) channels. Because this response is controlled by Kv1 accessory subunits (i.e., Kvß), which are NAD(P)(H)-dependent aldo-keto reductases, we tested the hypothesis that oxygen demand modifies arterial [NAD(H)]i, and that resultant cytosolic pyridine nucleotide redox state influences Kv1 activity. High-resolution imaging mass spectrometry and live-cell imaging reveal cardiac workload-dependent increases in NADH:NAD+ in intramyocardial arterial myocytes. Intracellular NAD(P)(H) redox ratios reflecting elevated oxygen demand potentiate native coronary Kv1 activity in a Kvß2-dependent manner. Ablation of Kvß2 catalysis suppresses redox-dependent increases in Kv1 activity, vasodilation, and the relationship between cardiac workload and myocardial blood flow. Collectively, this work suggests that the pyridine nucleotide sensitivity and enzymatic activity of Kvß2 controls coronary vasoreactivity and myocardial blood flow during metabolic stress.

Mortality risk associated with greenness, air pollution, and physical activity in a representative U.S. cohort.

Several cohort studies suggest greenness is associated with decreased mortality risk. Potential confounding by or interactions between physical activity and air pollution remains unclear. This study evaluates associations of greenness, air pollution, and physical activity with mortality risk and investigates confounding and effect modification across these key risk factors. National Health Interview Survey (NHIS) data covering 1997-2014 were linked to the National Death Index to generate a cohort of 403,748 individuals with 39,528 deaths. Greenness, represented by census-tract Normalized Difference Vegetation Index (NDVI) for the seasonal period of May-October, was averaged over the years 2003-2016. Air pollution was estimated by census-tract level PM2.5 concentrations from 1999 to 2015. Cox Proportional Hazard Models were used to estimate hazard ratios (HR) for differences in greenness, air pollution, and physical activity. Alternative models that evaluated potential confounding and stratified models that evaluated effect modification were examined. Mortality risks were associated with PM2.5 (HR = 1.14, 95% CI: 1.09-1.19 per 10 µg/m3) and physical inactivity (1.49, 1.44-1.54 relative to sufficiently active), but not with greenness (1.01, 0.99-1.03 per IQR). The PM2.5-mortality association was mitigated at high levels of greenness (1.05, 0.91-1.22). There was no strong evidence of confounding between air pollution, physical activity, and greenness. However, stratified analysis suggested effect modification for PM2.5 and NDVI by physical activity. A significant protective greenness-mortality association was observed for only highly active individuals (0.91, 0.86-0.96). Also, relatively high PM2.5-mortality HRs were observed for more physically active individuals (1.25, 1.12-1.40). PM2.5 air pollution and physical inactivity are robustly associated with mortality risk. Greenness may be most beneficial and air pollution relatively harmful to highly active individuals. This analysis provides evidence that, in addition to not smoking, being physically active and living in a clean, green environment contributes to improved health and reduced risk of mortality.

Electronic Cigarette Solvents, JUUL E-Liquids, and Biomarkers of Exposure: In Vivo Evidence for Acrolein and Glycidol in E-Cig-Derived Aerosols.

Despite the increasing popularity of e-cigarettes, their long-term health effects remain unknown. In animal models, exposure to e-cigarette has been reported to result in pulmonary and cardiovascular injury, and in humans, the acute use of e-cigarettes increases heart rate and blood pressure and induces endothelial dysfunction. In both animal models and humans, cardiovascular dysfunction associated with e-cigarettes has been linked to reactive aldehydes such as formaldehyde and acrolein generated in e-cigarette aerosols. These aldehydes are known products of heating and degradation of vegetable glycerin (VG) present in e-liquids. Here, we report that in mice, acute exposure to a mixture of propylene glycol:vegetable glycerin (PG:VG) or to e-cigarette-derived aerosols significantly increased the urinary excretion of acrolein and glycidol metabolites─3-hydroxypropylmercapturic acid (3HPMA) and 2,3-dihydroxypropylmercapturic acid (23HPMA)─as measured by UPLC-MS/MS. In humans, the use of e-cigarettes led to an increase in the urinary levels of 23HPMA but not 3HPMA. Acute exposure of mice to aerosols derived from PG:13C3-VG significantly increased the 13C3 enrichment of both urinary metabolites 13C3-3HPMA and 13C3-23HPMA. Our stable isotope tracing experiments provide further evidence that thermal decomposition of vegetable glycerin in the e-cigarette solvent leads to generation of acrolein and glycidol. This suggests that the adverse health effects of e-cigarettes may be attributable in part to these reactive compounds formed through the process of aerosolizing nicotine. Our findings also support the notion that 23HPMA, but not 3HPMA, may be a relatively specific biomarker of e-cigarette use.

Environmental exposure to volatile organic compounds is associated with endothelial injury.

OBJECTIVE: Volatile organic compounds (VOCs) are airborne toxicants abundant in outdoor and indoor air. High levels of VOCs are also present at various Superfund and other hazardous waste sites; however, little is known about the cardiovascular effects of VOCs. We hypothesized that ambient exposure to VOCs exacerbate cardiovascular disease (CVD) risk by depleting circulating angiogenic cells (CACs). APPROACH AND RESULTS: In this cross-sectional study, we recruited 603 participants with low-to-high CVD risk and measured 15 subpopulations of CACs by flow cytometry and 16 urinary metabolites of 12 VOCs by LC/MS/MS. Associations between CAC and VOC metabolite levels were examined using generalized linear models in the total sample, and separately in non-smokers. In single pollutant models, metabolites of ethylbenzene/styrene and xylene, were negatively associated with CAC levels in both the total sample, and in non-smokers. The metabolite of acrylonitrile was negatively associated with CD45dim/CD146+/CD34+/AC133+ cells and CD45+/CD146+/AC133+, and the toluene metabolite with AC133+ cells. In analysis of non-smokers (n = 375), multipollutant models showed a negative association with metabolites of ethylbenzene/styrene, benzene, and xylene with CD45dim/CD146+/CD34+ cells, independent of other VOC metabolite levels. Cumulative VOC risk score showed a strong negative association with CD45dim/CD146+/CD34+ cells, suggesting that total VOC exposure has a cumulative effect on pro-angiogenic cells. We found a non-linear relationship for benzene, which showed an increase in CAC levels at low, but depletion at higher levels of exposure. Sex and race, hypertension, and diabetes significantly modified VOC associated CAC depletion. CONCLUSION: Low-level ambient exposure to VOCs is associated with CAC depletion, which could compromise endothelial repair and angiogenesis, and exacerbate CVD risk.