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Because little is known about the effects of individual flavorants in electronic cigarette (e-cig) fluids on human platelet aggregation, we tested for the direct effects of 15 common e-cig flavorants on adenosine diphosphate (ADP)-induced human platelet aggregation

Chronic exposure to ambient particulate matter (PM) increases the risk of cardiovascular disease (CVD). One proposed mechanism linking PM exposure and CVD is the induction of low-grade systemic inflammation that underlies disease progression. However, whether exposure to fine PM (PM 2.5 ) directly affects the endogenous pathways that resolve the inflammatory response is not known. Resolution of inflammation is distinct from anti-inflammation in that rather than blunting the magnitude of the initial inflammatory response, it is the active promotion and acceleration of its decay. Defective or insufficient resolution is a hallmark of many chronic inflammatory diseases including atherosclerosis and diabetes. Therefore, the overall goal of this study was to elucidate how PM exposure impacts the resolution of inflammation and how this relates to the subtle, but extensive pathological changes brought about by PM exposure. We found that in mice exposed PM 2.5 for 30 days there was a significant decrease in the abundance of specialized lipid mediators that promote resolution (SPMs) in the spleen. The changes in spleen are particularly critical due to its central role in regulating immune response dynamics and as a filter to remove senescent and damaged erythrocytes. While SPMs are known to enhance macrophage erythrophagocytosis ex vivo , how decreased in vivo abundance affects splenic function remains unclear. Therefore, we performed RNA sequencing of PM 2.5 -exposed spleens and found that numerous pathways involved in both erythrophagocytosis and myelopoiesis were significantly upregulated, including those related to myeloid cell homeostasis and development, erythrocyte differentiation, iron ion homeostasis, and heme biosynthesis and metabolism. Additionally, we identified significant alterations in circulating red blood cells, including decreased expression of CD47, a prominent marker of self and “don’t eat me signal”, on the surface of circulating erythrocytes after exposure to PM 2.5 , as well as increased red cell distribution width. Together, these data suggest that PM exposure alters red blood cells and may stimulate enhanced erythrophagocytosis in the spleen, increasing red blood cell turnover.

BACKGROUND AND AIMS Fibroblast growth factor (FGF) 1 demonstrated protection against nonalcoholic fatty liver disease (NAFLD) in type 2 diabetic and obese mice by an uncertain mechanism. This study investigated the therapeutic activity and mechanism of a nonmitogenic FGF1 variant carrying 3 substitutions of heparin-binding sites (FGF1△HBS ) against NAFLD. APPROACH AND RESULTS FGF1△HBS administration was effective in 9-month-old diabetic mice carrying a homozygous mutation in the leptin receptor gene (db/db) with NAFLD; liver weight, lipid deposition, and inflammation declined and liver injury decreased. FGF1△HBS reduced oxidative stress by stimulating nuclear translocation of nuclear erythroid 2 p45-related factor 2 (Nrf2) and elevation of antioxidant protein expression. FGF1△HBS also inhibited activity and/or expression of lipogenic genes, coincident with phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and its substrates. Mechanistic studies on palmitate exposed hepatic cells demonstrated that NAFLD-like oxidative damage and lipid accumulation could be reversed by FGF1△HBS . In palmitate-treated hepatic cells, small interfering RNA (siRNA) knockdown of Nrf2 abolished only FGF1△HBS antioxidative actions but not improvement of lipid metabolism. In contrast, AMPK inhibition by pharmacological agent or siRNA abolished FGF1△HBS benefits on both oxidative stress and lipid metabolism that were FGF receptor (FGFR) 4 dependent. Further support of these in vitro findings is that liver-specific AMPK knockout abolished therapeutic effects of FGF1△HBS against high-fat/high-sucrose diet-induced hepatic steatosis. Moreover, FGF1△HBS improved high-fat/high-cholesterol diet-induced steatohepatitis and fibrosis in apolipoprotein E knockout mice. CONCLUSIONS These findings indicate that FGF1△HBS is effective for preventing and reversing liver steatosis and steatohepatitis and acts by activation of AMPK through hepatocyte FGFR4.

Environmental air pollution exposure is a leading cause of death worldwide, and with increasing industrialization and urbanization, its disease burden is expected to rise even further. The majority of air pollution exposure-associated deaths are linked to cardiovascular disease (CVD). Although ample research demonstrates a strong correlation between air pollution exposure and CVD risk, the mechanisms by which inhalation of polluted air affects cardiovascular health are not completely understood. Inhalation of environmental air pollution has been associated with endothelial dysfunction, which suggests that air pollution exposure impacts CVD health by inducing endothelial injury. Interestingly, recent studies demonstrate that air pollution exposure affects the number and function of endothelial progenitor cells (EPCs), subpopulations of bone marrow-derived proangiogenic cells that have been shown to play an essential role in maintaining cardiovascular health. In line with their beneficial function, chronically low levels of circulating EPCs and EPC dysfunction (e.g., in diabetic patients) have been associated with vascular dysfunction, poor cardiovascular health, and increases in the severity of cardiovascular outcomes. In contrast, treatments that improve EPC number and function (e.g., exercise) have been found to attenuate cardiovascular dysfunction. Considering the critical, nonredundant role of EPCs in maintaining vascular health, air pollution exposure-induced impairments in EPC number and function could lead to endothelial dysfunction, consequently increasing the risk for CVD. This review article covers novel aspects and new mechanistic insights of the adverse effects of air pollution exposure on cardiovascular health associated with changes in EPC number and function.

After more than a decade of electronic cigarette (E-cig) use in the United States, uncertainty persists regarding E-cig use and long-term cardiopulmonary disease risk. As all E-cigs use propylene glycol and vegetable glycerin (PG-VG) and generate abundant saturated aldehydes, mice were exposed by inhalation to PG-VG–derived aerosol, formaldehyde (FA), acetaldehyde (AA), or filtered air. Biomarkers of exposure and cardiopulmonary injury were monitored by mass spectrometry (urine metabolites), radiotelemetry (respiratory reflexes), isometric myography (aorta), and flow cytometry (blood markers). Acute PG-VG exposure significantly affected multiple biomarkers including pulmonary reflex (decreased respiratory rate, −50%), endothelium-dependent relaxation (−61.8 ± 4.2%), decreased WBC (−47 ± 7%), and, increased RBC (+6 ± 1%) and hemoglobin (+4 ± 1%) versus air control group. Notably, FA exposure recapitulated the prominent effects of PG-VG aerosol on pulmonary irritant reflex and endothelial dysfunction, whereas AA exposure did not. To attempt to link PG-VG exposure with FA or AA exposure, urinary formate and acetate levels were measured by GC-MS. Although neither FA nor AA exposure altered excretion of their primary metabolite, formate or acetate, respectively, compared with air-exposed controls, PG-VG aerosol exposure significantly increased post-exposure urinary acetate but not formate. These data suggest that E-cig use may increase cardiopulmonary disease risk independent of the presence of nicotine and/or flavorings. This study indicates that FA levels in tobacco product-derived aerosols should be regulated to levels that do not induce biomarkers of cardiopulmonary harm. There remains a need for reliable biomarkers of exposure to inhaled FA and AA. NEW & NOTEWORTHY Use of electronic cigarettes (E-cig) induces endothelial dysfunction (ED) in healthy humans, yet the specific constituents in E-cig aerosols that contribute to ED are unknown. Our study implicates formaldehyde that is formed in heating of E-cig solvents (propylene glycol, PG; vegetable glycerin, VG). Exposure to formaldehyde or PG-VG–derived aerosol alone stimulated ED in female mice. As ED was independent of nicotine and flavorants, these data reflect a “universal flaw” of E-cigs that use PG-VG. Listen to this article’s corresponding podcast at https://ajpheart.podbean.com/e/e-cigarettes-aldehydes-and-endothelial-dysfunction/.

Background: The regenerative capacity of the heart after myocardial infarction is limited. Our previous study showed that ectopic introduction of 4 cell cycle factors (4F; CDK1 [cyclin-dependent kinase 1], CDK4 [cyclin-dependent kinase 4], CCNB [cyclin B1], and CCND [cyclin D1]) promotes cardiomyocyte proliferation in 15% to 20% of infected cardiomyocytes in vitro and in vivo and improves cardiac function after myocardial infarction in mice. Methods: Using temporal single-cell RNA sequencing, we aimed to identify the necessary reprogramming stages during the forced cardiomyocyte proliferation with 4F on a single cell basis. Using rat and pig models of ischemic heart failure, we aimed to start the first preclinical testing to introduce 4F gene therapy as a candidate for the treatment of ischemia-induced heart failure. Results: Temporal bulk and single-cell RNA sequencing and further biochemical validations of mature human induced pluripotent stem cell–derived cardiomyocytes treated with either LacZ or 4F adenoviruses revealed full cell cycle reprogramming in 15% of the cardiomyocyte population at 48 hours after infection with 4F, which was associated mainly with sarcomere disassembly and metabolic reprogramming (n=3/time point/group). Transient overexpression of 4F, specifically in cardiomyocytes, was achieved using a polycistronic nonintegrating lentivirus (NIL) encoding 4F; each is driven by a TNNT2 (cardiac troponin T isoform 2) promoter (TNNT2-4Fpolycistronic-NIL). TNNT2-4Fpolycistronic-NIL or control virus was injected intramyocardially 1 week after myocardial infarction in rats (n=10/group) or pigs (n=6–7/group). Four weeks after injection, TNNT2-4Fpolycistronic-NIL–treated animals showed significant improvement in left ventricular ejection fraction and scar size compared with the control virus–treated animals. At 4 months after treatment, rats that received TNNT2-4Fpolycistronic-NIL still showed a sustained improvement in cardiac function and no obvious development of cardiac arrhythmias or systemic tumorigenesis (n=10/group). Conclusions: This study provides mechanistic insights into the process of forced cardiomyocyte proliferation and advances the clinical feasibility of this approach by minimizing the oncogenic potential of the cell cycle factors owing to the use of a novel transient and cardiomyocyte-specific viral construct.

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

Introduction: Pod-based e-cigarettes including JUUL represent the most commonly used product type and more efficiently deliver nicotine; however, their cardiovascular effects are poorly understood. Methods: We evaluated endothelial function (cell viability by TUNEL and nitric oxide bioavailability using DAF-2DA) in human aortic endothelial cells (HAECs) exposed for 90 minutes to one of four JUUL pod flavors (Menthol, Mint, Mango and Virginia Tobacco) or constituents propylene glycol (PG)/vegetable glycerol (VG) at 30:70 ratio with and without nicotine salt, as well as their heated particle fractions separated with a mini-MOUDI impactor. In healthy young adults, we assessed endothelial cell function in nonusers of tobacco products, pod users and combustible cigarette users for eNOS activation. Results: We observed significant increases in cell death with JUUL e-liquid flavors across 0.0001-1% dilutions. PG/VG vehicle alone and with nicotine salt induced cell death to similar levels as the JUUL e-liquids. All JUUL e-liquids at 0.0001% dilution impaired A23187-stimulated nitric oxide production. Exposure to particle fractions of JUUL e-liquids at 0.001% dilution also reduced A23187-stimulated nitric oxide production. Endothelial cells from pod users showed reduced eNOS activation compared with nonusers and similar to reduced levels in combustible cigarette users (figure). Conclusions: Our data suggest endothelial toxicity of pod-based e-liquids and their constituents, including in young adult users.

Vast amounts of plastic materials are produced in the modern world and despite recycling efforts, large amounts are disposed in water systems and landfills. Under these storage conditions, physical weathering and photochemical processes break down these materials into smaller particles of the micro- and nano-scale. In addition, ecosystems can be contaminated with plastic particles which are manufactured in these size ranges for commercial purposes. Independent of source, microplastics are abundant in the environment and have found their way into water supplies and the food cycle where human exposure is inevitable. Nevertheless, the health consequences of microplastic ingestion, inhalation, or absorption are largely unknown. In this study we sought to determine if ingestion of microplastics promoted pre-clinical cardiovascular disease (CVD). To do this, we supplied mice with normal drinking water or that supplemented with polystyrene beads of two different sizes (0.5 µm and 5 µm) and two different doses (0.1 μg/ml and 1 μg/ml) each for 12 weeks and measured several indices of metabolism and glucose homeostasis. As early as 3 weeks of consumption, we observed an accelerated weight gain with a corresponding increase in body fat for some exposure groups versus the control mice. Some exposure groups demonstrated increased levels of fasting plasma glucose. Those mice consuming the smaller sized beads (0.5 µm) at the higher dose (1 μg/ml), had increased levels of fasting plasma insulin and higher homeostatic model assessment of insulin resistance (HOMA-IR) scores as well. This was accompanied by changes in the gut microbiome consistent with an obese phenotype. Using samples of perivascular adipose tissue collected from the same group, we observed changes in gene expression consistent with increased adipogenesis. These results suggest that ingestion of polystyrene beads promotes a cardiometabolic disease phenotype and thus may be an unrecognized risk factor for CVD.

Endothelial progenitor cells (EPCs) are reduced in number and impaired in function in diabetic patients. Whether and how Nrf2 regulates the function of diabetic EPCs remains unclear. In this study, we found that the expression of Nrf2 and its downstream genes were decreased in EPCs from both diabetic patients and db/db mice. Survival ability and angiogenic function of EPCs from diabetic patients and db/db mice also were impaired. Gain- and loss-of-function studies, respectively, showed that knockdown of Nrf2 increased apoptosis and impaired tube formation in EPCs from healthy donors and wild-type mice, while Nrf2 overexpression decreased apoptosis and rescued tube formation in EPCs from diabetic patients and db/db mice. Additionally, proangiogenic function of Nrf2-manipulated mouse EPCs was validated in db/db mice with hind limb ischemia. Mechanistic studies demonstrated that diabetes induced mitochondrial fragmentation and dysfunction of EPCs by dysregulating the abundance of proteins controlling mitochondrial dynamics; upregulating Nrf2 expression attenuated diabetes-induced mitochondrial fragmentation and dysfunction and rectified the abundance of proteins controlling mitochondrial dynamics. Further RNA-sequencing analysis demonstrated that Nrf2 specifically upregulated the transcription of isocitrate dehydrogenase 2 (IDH2), a key enzyme regulating tricarboxylic acid cycle and mitochondrial function. Overexpression of IDH2 rectified Nrf2 knockdown- or diabetes-induced mitochondrial fragmentation and EPC dysfunction. In a therapeutic approach, supplementation of an Nrf2 activator sulforaphane enhanced angiogenesis and blood perfusion recovery in db/db mice with hind limb ischemia. Collectively, these findings indicate that Nrf2 is a potential therapeutic target for improving diabetic EPC function. Thus, elevating Nrf2 expression enhances EPC resistance to diabetes-induced oxidative damage and improves therapeutic efficacy of EPCs in treating diabetic limb ischemia likely via transcriptional upregulating IDH2 expression and improving mitochondrial function of diabetic EPCs.

Benzene is a ubiquitous environmental pollutant abundant in household products, petrochemicals and cigarette smoke. Benzene is a well-known carcinogen in humans and experimental animals; however, little is known about the cardiovascular toxicity of benzene. Recent population-based studies indicate that benzene exposure is associated with an increased risk for heart failure. Nonetheless, it is unclear whether benzene exposure is sufficient to induce and/or exacerbate heart failure. We examined the effects of benzene (50 ppm, 6 h/day, 5 days/week, 6 weeks) or HEPA-filtered air exposure on transverse aortic constriction (TAC)-induced pressure overload in male C57BL/6J mice. Our data show that benzene exposure had no effect on cardiac function in the Sham group; however, it significantly compromised cardiac function as depicted by a significant decrease in fractional shortening and ejection fraction, as compared with TAC/Air-exposed mice. RNA-seq analysis of the cardiac tissue from the TAC/benzene-exposed mice showed a significant increase in several genes associated with adhesion molecules, cell-cell adhesion, inflammation, and stress response. In particular, neutrophils were implicated in our unbiased analyses. Indeed, immunofluorescence studies showed that TAC/benzene exposure promotes infiltration of CD11b+/S100A8+/myeloperoxidase+-positive neutrophils in the hearts by 3-fold. In vitro, the benzene metabolites, hydroquinone and catechol, induced the expression of P-selectin in cardiac microvascular endothelial cells by 5-fold and increased the adhesion of neutrophils to these endothelial cells by 1.5-2.0-fold. Benzene metabolite-induced adhesion of neutrophils to the endothelial cells was attenuated by anti-P-selectin antibody. Together, these data suggest that benzene exacerbates heart failure by promoting endothelial activation and neutrophil recruitment.

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Many CVDs begin with endothelium dysfunction (ED), including hypertension, thrombosis, and atherosclerosis. Our assay evaluated ED in isolated murine aorta by quantifying phenylephrine‐induced contractions (PE) in the presence of L‐NAME, which blocked acetylcholine‐induced relaxation (ACh %; >99%). The “L‐NAME PE Contraction Ratio” (PECR) was defined as: “PE Tension post‐L‐NAME” divided by “PE Tension pre‐L‐NAME.” We hypothesized that our novel PE Contraction Ratio would strongly correlate with alterations in endothelium function. Validation 1: PECR and ACh % values of naïve aortas were strongly and positively correlated (PECR vs. ACh %, r 2 = 0.91, n = 7). Validation 2: Retrospective analyses of published aortic PECR and ACh % data of female mice exposed to filtered air, propylene glycol:vegetable glycerin (PG:VG), formaldehyde (FA), or acetaldehyde (AA) for 4d showed that the PECR in air‐exposed mice (PECR = 1.43 ± 0.05, n = 16) correlated positively with the ACh % (r 2 = 0.40) as seen in naïve aortas. Similarly, PECR values were significantly decreased in aortas with ED yet retained positive regression coefficients with ACh % (PG:VG r 2 = 0.54; FA r 2 = 0.55). Unlike other toxicants, inhaled AA significantly increased both PECR and ACh % values yet diminished their correlation (r 2 = 0.09). Validation 3: To assess species‐specific dependence, we tested PECR in rat aorta, and found PECR correlated with ACh % relaxation albeit less well in this aged and dyslipidemic model. Because the PECR reflects NOS function directly, it is a robust measure of both ED and vascular dysfunction. Therefore, it is a complementary index of existing tests of ED that also provides insight into mechanisms of vascular toxicity., Endothelial dysfunction (ED) is sine qua non of atherosclerosis and other cardiovascular diseases in humans, yet the mechanisms that contribute to ED are still being investigated. Our study demonstrates a novel methodological twist using an old drug (L‐NAME) to screen for ED in aorta ex vivo.

Exposure to fine particulate matter (PM2.5) air pollution increases blood pressure, induces vascular inflammation and dysfunction, and augments atherosclerosis in humans and rodents; however, the understanding of early changes that foster chronic vascular disease is incomplete. Because perivascular adipose tissue (PVAT) inflammation is implicated in chronic vascular diseases, we investigated changes in aortic PVAT following short‐term air pollution exposure. Mice were exposed to HEPA‐filtered or concentrated ambient PM2.5 (CAP) for 9 consecutive days, and the abundance of inflammatory, adipogenic, and adipokine gene mRNAs was measured by gene array and qRT‐PCR in thoracic aortic PVAT. Responses of the isolated aorta with and without PVAT to contractile (phenylephrine, PE) and relaxant agonists (acetylcholine, ACh; sodium nitroprusside, SNP) were measured. Exposure to CAP significantly increased the urinary excretion of acrolein metabolite (3HPMA) as well as the abundance of protein–acrolein adducts (a marker of oxidative stress) in PVAT and aorta, upregulated PVAT leptin mRNA expression without changing mRNA levels of several proinflammatory genes, and induced PVAT insulin resistance. In control mice, PVAT significantly depressed PE‐induced contractions—an effect that was dampened by CAP exposure. Pulmonary overexpression of extracellular dismutase (ecSOD‐Tg) prevented CAP‐induced effects on urinary 3HPMA levels, PVAT Lep mRNA, and alterations in PVAT and aortic function, reflecting a necessary role of pulmonary oxidative stress in all of these deleterious CAP‐induced changes. More research is needed to address how exactly short‐term exposure to PM2.5 perturbs PVAT and aortic function, and how these specific genes and functional changes in PVAT could lead over time to chronic inflammation, endothelial dysfunction, and atherosclerosis., Short‐term (9‐day) exposure of mice to concentrated ambient particulate matter (CAP) alters the function of perivascular adipose tissue (PVAT) and aorta. Short‐term CAP exposure increased PVAT oxidative stress and leptin mRNA. Normally, PVAT and endothelium are anticontractile and modulate aortic vascular smooth muscle (VSMC) tone. After CAP exposure, however, the aorta becomes more contractile with accompanying loss of endothelial‐dependent modulation and increased PVAT‐dependent anticontractile function. The increased PVAT leptin may represent a compensatory response to maintain vascular tone balance. The CAP‐induced alterations in pulmonary and systemic oxidative stress, leptin mRNA abundance in PVAT, and aortic contractility were prevented in mice overexpressing pulmonary extracellular superoxide dismutase (ecSOD‐Tg) implicating pulmonary oxidative stress in CAP‐induced changes.

Myocardial ischemia-reperfusion (I/R) results in the generation of free radicals, accumulation of lipid peroxidation-derived unsaturated aldehydes, variable angina (pain), and infarction. The transient receptor potential ankyrin 1 (TRPA1) mediates pain signaling and is activated by unsaturated aldehydes, including acrolein and 4-hydroxynonenal. The contribution of TRPA1 (a Ca2+-permeable channel) to I/R-induced myocardial injury is unknown. We tested the hypothesis that cardiac TRPA1 confers myocyte sensitivity to aldehyde accumulation and promotes I/R injury. Although basal cardiovascular function in TRPA1-null mice was similar to that in wild-type (WT) mice, infarct size was significantly smaller in TRPA1-null mice than in WT mice (34.1 ± 9.3 vs. 14.3 ± 9.9% of the risk region, n = 8 and 7, respectively, P < 0.05), despite a similar I/R-induced area at risk (40.3 ±8.4% and 42.2 ± 11.3% for WT and TRPA1-null mice, respectively) after myocardial I/R (30 min of ischemia followed by 24 h of reperfusion) in situ. Positive TRPA1 immunofluorescence was present in murine and human hearts and was colocalized with connexin43 at intercalated disks in isolated murine cardiomyocytes. Cardiomyocyte TRPA1 was confirmed by quantitative RT-PCR, DNA sequencing, Western blot analysis, and electrophysiology. A role of TRPA1 in cardiomyocyte toxicity was demonstrated in isolated cardiomyocytes exposed to acrolein, an I/R-associated toxin that induces Ca2+ accumulation and hypercontraction, effects significantly blunted by HC-030031, a TRPA1 antagonist. Protection induced by HC-030031 was quantitatively equivalent to that induced by SN-6, a Na+/Ca2+ exchange inhibitor, further supporting a role of Ca2+ overload in acrolein-induced cardiomyocyte toxicity. These data indicate that cardiac TRPA1 activation likely contributes to I/R injury and, thus, that TRPA1 may be a novel therapeutic target for decreasing myocardial I/R injury. NEW & NOTEWORTHY Transient receptor potential ankyrin 1 (TRPA1) activation mediates increased blood flow, edema, and pain reception, yet its role in myocardial ischemia-reperfusion (I/R) injury is unknown. Genetic ablation of TRPA1 significantly decreased myocardial infarction after I/R in mice. Functional TRPA1 in cardiomyocytes was enriched in intercalated disks and contributed to acrolein-induced Ca2+ overload and hypercontraction. These data indicate that I/R activation of TRPA1 worsens myocardial infarction; TRPA1 may be a potential target to mitigate I/R injury.

Acute and chronic exposures to particulate matter (PM2.5) air pollution increase the risk for cardiovascular disease (CVD). A hypothesized mechanism linking PM2.5 exposure and CVD is the induction of endothelial dysfunction – a key step to increased CVD risk. Although PM2.5 exposure is associated with endothelial dysfunction and the vasoconstrictor peptide endothelin-1 (ET-1) is upregulated in endothelial dysfunction, the effects of PM2.5 on ET-1 and whether or not ET-1 mediates the downstream effects of PM2.5 are unclear. In addition to examining associations between acute changes in ambient PM2.5 and circulating levels of ET-1, we also looked at whether changes in ET-1 were associated with changes in markers of vascular health and systemic injury. For example, endothelial function is maintained in part by circulating angiogenic cell (CAC)-mediated repair, and our recent studies show that CACs in humans and mice are decreased by ambient PM2.5 exposure. In the current study, we recruited young, healthy adults who were exposed to natural variations in PM2.5, and we analyzed associations between PM2.5 and circulating levels of ET-1, between ET-1 and CACs, and between ET-1 and other biomarkers of injury using linear regression analyses. Surprisingly, ET-1 levels were negatively associated with PM2.5 levels (β = −0.773, P = 0.0005), yet, in contrast, positively associated with two CACs: CAC-2 (CD31 + /CD34 + /CD45 + ) and CAC-4 (CD31 + /CD34 + /CD45 + /CD133 + ). Interestingly, ET-1 levels were negatively associated with some biomarkers (platelet factor 4, β = −0.148, P = 0.0003; triglycerides, β = −0.095, P = 0.041) and positively with other biomarkers: albumin (β = 0.035, P = 0.006) and IL-1β (β = 0.082, P = 0.012). These findings further reveal the insidious nature of PM2.5’s anti-angiogenic effect including a novel relationship between ET-1 and CACs in young adults exposed to acute elevations of air pollution.

Increased interest in volatile organic compound (VOC) exposure has led to an increased need for consistent, systematic, and informative naming of VOC metabolites. As analytical methods have expanded to include many metabolites in a single assay, the number of acronyms in use for a single metabolite has expanded in an unplanned and inconsistent manner due to a lack of guidance or group consensus. Even though the measurement of VOC metabolites is a well-established means to investigate exposure to VOCs, a formal attempt to harmonize acronyms amongst investigators has not been published. The aim of this work is to establish a system of acronym naming that provides consistency in current acronym usage and a foundation for creating acronyms for future VOC metabolites.

Background: E-cigarette (e-cig) use has rapidly increased, especially among youth. Vaping has been linked to adverse cardiopulmonary effects, but the full extent of effects remains unknown. Several constituents in e-cigs may increase cardiac risk partly by disturbing cardiac electrophysiology and the autonomic nervous system. Hypothesis: E-cig aerosols will differentially induce pro-arrhythmic changes in cardiac conduction and autonomic balance in mice depending on the presence of nicotine and flavors. Methods: Electrocardiograms (ECGs) were collected by telemetry in 5 healthy male mice (C57BL/6) exposed for 6 hours to clean air or e-cig aerosols (9-minute puff sessions every 18 minutes) from JUUL e-liquids (Va. Tobacco, Mango, or Menthol at ≈5% nicotine benzoate), or a nicotine-free mixture of propylene glycol and vegetable glycerin solvents (PG:VG, 30:70 ratio). ECG morphology, heart rate variability (HRV), and arrhythmias were analyzed by mixed models with P < 0.05 (vs. Air) for all effects. Results: PG:VG increased high grade supraventricular block arrhythmias (121±45 events/hour) relative to Air (0±0 events/hour) and decreased heart rate (HR, -25±8 beats/min), whereas aerosols from all nicotine-containing e-liquids increased HR and decreased HRV, suggesting sympatho-excitation. However, these effects were significantly attenuated for Mango relative to Menthol and Va. Tobacco. As well, only PG:VG and Mango increased ventricular premature beats (VPBs, 9.6±3.7 and 5.5±1.2 events/hour, ±SEM) relative to Air (1.1±0.24 events/hour). VPBs correlated with changes in standard deviation of RR and mean HR from pre-exposure (Spearman’s r : 0.51 and -0.27, P < 0.0001). Prolonged repolarization (QTc) correlated with VPBs during exposures to PG:VG ( r = 0.38, P = 0.046), but not nicotine-containing e-liquids ( r = 0.15, P = 0.38). Conclusions: E-cigs may increase risk for cardiac arrhythmia through e-liquid solvents, which when thermally aerosolized generate toxic aldehydes and particulates. Nicotine and flavor chemicals may modify the cardiac and autonomic impacts of e-cigs. Further studies are needed to determine how e-cig aerosols induce cardiac arrhythmia and whether these effects translate to cardiac morbidity and mortality in humans.

Introduction: After a decade of electronic cigarettes (E-cig) in the U.S., 3 elements remain: 1) E-cigs evolve; 2) E-cigs use propylene glycol (PG) and vegetable glycerin (VG); and, 3) uncertainty about E-cig use and CVD risk. Because all E-cigs use PG:VG, we tested for vascular effects of PG:VG-derived aerosol alone. Methods: Female C57BL/6 mice were exposed by inhalation (6h/d*4d) to filtered air (n=10) or to PG:VG-derived aerosol (n=10). After exposures, blood and aortas were examined for changes in: circulating immune and stem cells and platelets by flow cytometry, and vascular function by isometric myography. Results: PG:VG exposure significantly decreased WBC (-47±7%); increased RBC (+6±1%) and hemoglobin (+4±1%), but had no effect on circulating angiogenic cells or platelet-leukocyte aggregates. In aorta, vascular smooth muscle (VSM) function measured as aortic contractility to phenylephrine (PE) was unaltered. However, acetylcholine (ACh)-induced, endothelium-dependent relaxation was significantly decreased (air: -75.5±4.2%; PG:VG: -61.8±4.2%; P50 : 166±54nM; PG:VG EC 50 : 1020±435nM; 0.0550 : 8.8±0.8nM; % relaxation: -99.0±0.3%) vs air group (EC 50 : 11.1±1.0nM; % relaxation: -99.1±0.3%) indicating a loss of ACh responsiveness was independent of VSM. To test whether eNOS was altered by PG:VG, PE response was done in presence of eNOS inhibitor (LNAME). The ‘PE contraction ratio’ (i.e., Tension PE+LNAME / Tension PE alone ) was significantly decreased in PG:VG group (1.28±0.03) vs air group (1.39±0.20; P Conclusions: Acute exposure to E-cig solvent aerosol alone led to endothelial dysfunction and immune cell changes suggesting that E-cig use may increase CVD risk independently of nicotine and flavor constituents. Perhaps thermal degradation of PG and VG into aldehydes may contribute to endothelial dysfunction.

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Maternal exposures during pregnancy affect the onset and progression of adult diseases in the offspring. A prior mouse study indicated that maternal tobacco smoke exposure affects hepatic fibrosis in adult offspring. Gutkha, a broadly used smokeless tobacco (ST) product, is widely used by pregnant woman in many countries. The objective of this murine study was to evaluate whether oral maternal exposure to gutkha during pregnancy alters non-alcoholic fatty liver disease (NAFLD) in adult offspring: risk factors for the progression of NAFLD to cirrhosis in adults remain elusive. Buccal cavity &lsquo, painting&rsquo, of pregnant mice with gutkha began on gestational days (GD) 2&ndash, 4 and continued until parturition. Beginning at 12 weeks of age, a subset of offspring were transitioned to a high-fat diet (HFD). Results demonstrated that prenatal exposure to gutkha followed by an HFD in adulthood significantly increased the histologic evidence of fatty liver disease only in adult male offspring. Changes in hepatic fibrosis-related cytokines (interleukin (IL)-1b and IL-6) and in hepatic collagen mRNA expression were observed when comparing adult male offspring exposed to gutkha in utero to those not exposed. These findings indicate that maternal use of gutkha during pregnancy affects NAFLD in adult offspring in a sex-dependent manner.

PURPOSE OF REVIEW: Tobacco smoking is the most significant modifiable risk factor in the development of cardiovascular disease (CVD). Exposure to mainstream cigarette smoke (MCS) is associated with CVD through the development of endothelial dysfunction, a condition characterized by an imbalance of vasoactive factors in the vasculature. This dysfunction is thought to be induced in part by aldehydes generated at high levels in MCS. RECENT FINDINGS: Electronic cigarettes (e-cigs) may also pose CVD risk. Although the health effects of e-cigs are still largely unknown, the presence of aldehydes in e-cig aerosol suggests that e-cigs may induce adverse cardiovascular outcomes similar to those seen with MCS exposure. SUMMARY: Herein, we review studies of traditional and emerging tobacco product use, shared harmful and potentially harmful constituents, and measures of biomarkers of harm (endothelial dysfunction) to examine a potential and distinct role of aldehydes in cardiovascular harm associated with cigarette and e-cig use.

The limited availability of human heart tissue and its complex cell composition are major limiting factors for reliable testing drug efficacy, toxicity and understanding mechanism. Recently, we developed a functional human and pig heart slice biomimetic culture system that fully preserves the viability and functionality of 300 µm heart slices for 6 days. Here, we tested the reliability of this culture system in delineating the mechanisms of known anti-cancer drugs that cause cardiomyopathy. We tested three anti-cancer drugs (doxorubicin, trastuzumab, and sunitinib) associated with different mechanisms leading to cardiotoxicity at three concentrations and assessed the effect of these drugs on heart slice viability, structure, function and transcriptome. Slices incubated with any of these drugs for 48 h showed significant loss in viability, cardiomyocyte structure and functionality. Mechanistically, RNA sequencing demonstrated a significant downregulation of cardiac genes and upregulation of oxidative response in doxorubicin-treated tissues. Trastuzumab treatment caused major downregulation in cardiac muscle contraction-related genes, consistent with its clinically known direct effect on cardiomyocytes. Interestingly, sunitinib treatment resulted in significant downregulation of angiogenesis-related genes in line with its mechanism of action. Heart slices are not only able to demonstrate the expected toxicity of doxorubicin and trastuzumab similar to hiPS-derived-cardiomyocytes; they are superior in detecting sunitinib cardiotoxicity phenotypes and mechanism in the clinically relevant concentration range, 100 nM – 1 µM. These results indicate that heart slice tissue culture models have the potential to become a reliable platform for testing drug toxicity and mechanism of action.

BACKGROUND Myocardial ischemia reperfusion (I/R) injury is associated with complex pathophysiological changes characterized by pH imbalance, the accumulation of lipid peroxidation products acrolein and 4‐hydroxy trans ‐2‐nonenal, and the depletion of ATP levels. Cardioprotective interventions, designed to address individual mediators of I/R injury, have shown limited efficacy. The recently identified enzyme ATPGD1 (Carnosine Synthase), which synthesizes histidyl dipeptides such as carnosine, has the potential to counteract multiple effectors of I/R injury by buffering intracellular pH and quenching lipid peroxidation products and may protect against I/R injury . METHODS AND RESULTS We report here that β‐alanine and carnosine feeding enhanced myocardial carnosine levels and protected the heart against I/R injury. Cardiospecific overexpression of ATPGD 1 increased myocardial histidyl dipeptides levels and protected the heart from I/R injury. Isolated cardiac myocytes from ATPGD 1‐transgenic hearts were protected against hypoxia reoxygenation injury. The overexpression of ATPGD 1 prevented the accumulation of acrolein and 4‐hydroxy trans ‐2‐nonenal–protein adducts in ischemic hearts and delayed acrolein or 4‐hydroxy trans ‐2‐nonenal–induced hypercontracture in isolated cardiac myocytes. Changes in the levels of ATP , high‐energy phosphates, intracellular pH, and glycolysis during low‐flow ischemia in the wild‐type mice hearts were attenuated in the ATPGD 1‐transgenic hearts. Two natural dipeptide analogs (anserine and balenine) that can either quench aldehydes or buffer intracellular pH , but not both, failed to protect against I/R injury. CONCLUSIONS Either exogenous administration or enhanced endogenous formation of histidyl dipeptides prevents I/R injury by attenuating changes in intracellular pH and preventing the accumulation of lipid peroxidation derived aldehydes.

Diabetes-induced oxidative stress is one of the major contributors to dysfunction of endothelial progenitor cells (EPCs) and impaired endothelial regeneration. Thus, we tested whether increasing antioxidant protein metallothionein (MT) in EPCs promotes angiogenesis in a hind limb ischemia (HLI) model in endothelial MT transgenic (JTMT) mice with high fat diet and streptozocin-induced diabetes. Compared with littermate wild-type (WT) diabetic mice, JTMT diabetic mice had improved blood flow recovery and angiogenesis after HLI. Similarly, transplantation of JTMT bone marrow-derived mononuclear cells (BM-MNCs) stimulated greater blood flow recovery in db/db mice with HLI than did WT BM-MNCs. The improved recovery was associated with augmented EPC mobilization and angiogenic function. Further, cultured EPCs from diabetic patients exhibited decreased MT expression, increased cell apoptosis and impaired tube formation; while cultured JTMT-EPCs had enhanced cell survival, migration, and tube formation in hypoxia/hyperglycemic conditions compared with WT-EPCs. Mechanistically, MT overexpression enhanced hypoxia-inducible factor 1α (HIF-1α), stromal cell-derived factor (SDF-1) and vascular endothelial growth factor (VEGF) expression, and reduced oxidative stress in ischemic tissues. MT’s pro-EPC effects were abrogated by siRNA knockdown of HIF-1α without affecting MT’s anti-oxidant action. These results indicate that endothelial MT overexpression is sufficient to protect against diabetes-induced impairment of angiogenesis by promoting EPC functions most likely through upregulation of HIF-1α/SDF-1/VEGF signaling and reducing oxidative stress.

Although crotonaldehyde (CR) is an abundant α,β-unsaturated aldehyde in mainstream cigarette smoke (MCS), the cardiovascular toxicity of inhaled CR is largely unexplored. Thus, male C57BL/6 J mice were exposed acutely (1 h, 6 h, and 4d) and chronically (12 weeks) to CR (at levels relevant to MCS; 1 and 3 ppm), and cardiovascular and systemic outcomes were measured in vivo and in vitro. Diastolic blood pressure was decreased (hypotension) by both acute and chronic CR exposure. Vascular toxicity of inhaled CR was quantified in isolated aorta in response to agonists of contraction (phenylephrine, PE) and relaxation (acetylcholine, ACh; sodium nitroprusside, SNP). Although no change in contractility was observed, ACh-induced relaxations were augmented after both acute and chronic CR exposures whereas SNP-induced relaxation was enhanced only following 3 ppm CR exposure. Because CR is a known agonist of the transient receptor potential ankyrin 1 (TRPA1) channel, male TRPA1-null mice were exposed to air or CR (4d, 1 ppm) and aortic function assessed in vitro. CR exposure had no effect on TRPA1-null aortic function indicating a role of TRPA1 in CR effects in C57BL/6 J mice. Notably, CR exposure (4d, 1 ppm) had no effect on aortic function in female C57BL/6 J mice. This study shows that CR inhalation exposure induces real-time and persistent vascular changes that promote hypotension—a known risk factor for stroke. Because of continued widespread exposures of humans to combustion-derived CR (environmental and tobacco products), CR may be an important cardiovascular disease risk factor.

Acute and chronic exposures to particulate matter (PM2.5) air pollution increase the risk for cardiovascular disease (CVD). A hypothesized mechanism linking PM2.5 exposure and CVD is the induction of endothelial dysfunction - a key step to increased CVD risk. Although PM2.5 exposure is associated with endothelial dysfunction and the vasoconstrictor peptide endothelin-1 (ET-1) is upregulated in endothelial dysfunction, the effects of PM2.5 on ET-1 and whether or not ET-1 mediates the downstream effects of PM2.5 are unclear. In addition to examining associations between acute changes in ambient PM2.5 and circulating levels of ET-1, we also looked at whether changes in ET-1 were associated with changes in markers of vascular health and systemic injury. For example, endothelial function is maintained in part by circulating angiogenic cell (CAC)-mediated repair, and our recent studies show that CACs in humans and mice are decreased by ambient PM2.5 exposure. In the current study, we recruited young, healthy adults who were exposed to natural variations in PM2.5, and we analyzed associations between PM2.5 and circulating levels of ET-1, between ET-1 and CACs, and between ET-1 and other biomarkers of injury using linear regression analyses. Surprisingly, ET-1 levels were negatively associated with PM2.5 levels (β = −0.773, P = 0.0005), yet, in contrast, positively associated with two CACs: CAC-2 (CD31+/CD34+/CD45+) and CAC-4 (CD31+/CD34+/CD45+/CD133+). Interestingly, ET-1 levels were negatively associated with some biomarkers (platelet factor 4, β = −0.148, P = 0.0003; triglycerides, β = −0.095, P = 0.041) and positively with other biomarkers: albumin (β = 0.035, P = 0.006) and IL-lβ (β = 0.082, P = 0.012). These findings further reveal the insidious nature of PI2.5’s anti-angiogenic effect including a novel relationship between ET-1 and CACs in young adults exposed to acute elevations of air pollution.

Introduction Crotonaldehyde (CR) is an electrophilic α,β-unsaturated aldehyde present in foods and beverages and is a minor metabolite of 1,3-butadiene. CR is a product of incomplete combustion, and is at high levels in smoke of cigarettes and structural fires. Exposure to CR has been linked to cardiopulmonary toxicity and cardiovascular disease. Objective The purpose of this study was to examine the direct effects of CR in murine blood vessels (aorta and superior mesenteric artery, SMA) using an in vitro system. Methods and results CR induced concentration-dependent (1–300 μM) relaxations (75–80%) in phenylephrine (PE) precontracted aorta and SMA. Because the SMA was 20× more sensitive to CR than aorta (SMA EC50 3.8 ± 0.5 μM; aorta EC50 76.0 ± 2.0 μM), mechanisms of CR relaxation were studied in SMA. The CR-induced relaxation at low concentrations (1–30 μM) was inhibited by: 1) mechanically-impaired endothelium; 2) Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME); 3) guanylyl cyclase (GC) inhibitor (ODQ); 4) transient receptor potential ankyrin-1 (TRPA1) antagonist (A967079); and, 5) by non-vasoactive level of nicotine (1 μM). Similarly, a TRPA1 agonist, allyl isothiocyanate (AITC; mustard oil), stimulated SMA relaxation dependent on TRPA1, endothelium, NO, and GC. Consistent with these mechanisms, TRPA1 was present in the SMA endothelium. CR, at higher concentrations (100–300 μM), induced tension oscillations (spasms) and irreversibly impaired contractility (a vasotoxic effect enhanced by impaired endothelium). Conclusions CR relaxation depends on a functional endothelium and TRPA1, whereas vasotoxicity is enhanced by endothelium dysfunction. Thus, CR is both vasoactive and vasotoxic along a concentration continuum.

Background Cigarette smoking is associated with an increase in cardiovascular disease risk, attributable in part to reactive volatile organic chemicals (VOCs). However, little is known about the extent of VOC exposure due to the use of other tobacco products. Methods We recruited 48 healthy, tobacco users in four groups: cigarette, smokeless tobacco, occasional users of first generation e-cigarette and e-cigarette menthol and 12 healthy nontobacco users. After abstaining for 48 h, tobacco users used an assigned product. Urine was collected at baseline followed by five collections over a 3-h period to measure urinary metabolites of VOCs, nicotine, and tobacco alkaloids. Results Urinary levels of nicotine were ≃2-fold lower in occasional e-cigarette and smokeless tobacco users than in the cigarette smokers; cotinine and 3-hydroxycotinine levels were similar in all groups. Compared with nontobacco users, e-cigarette users had higher levels of urinary metabolites of xylene, cyanide, styrene, ethylbenzene, and benzene at baseline and elevated urinary levels of metabolites of xylene, N,N-dimethylformamide, and acrylonitrile after e-cigarette use. Metabolites of acrolein, crotonaldehyde, and 1,3-butadiene were significantly higher in smokers than in users of other products or nontobacco users. VOC metabolite levels in smokeless tobacco group were comparable to those found in nonusers with the exception of xylene metabolite—2-methylhippuric acid (2MHA), which was almost three fold higher than in nontobacco users. Conclusions Smoking results in exposure to a range of VOCs at concentrations higher than those observed with other products, and first generation e-cigarette use is associated with elevated levels of N,N-dimethylformamide and xylene metabolites. Implications This study shows that occasional users of first generation e-cigarettes have lower levels of nicotine exposure than the users of combustible cigarettes. Compared with combustible cigarettes, e-cigarettes, and smokeless tobacco products deliver lower levels of most VOCs, with the exception of xylene, N,N-dimethylformamide, and acrylonitrile, whose metabolite levels were higher in the urine of e-cigarette users than nontobacco users. Absence of anatabine in the urine of e-cigarette users suggests that measuring urinary levels of this alkaloid may be useful in distinguishing between users of e-cigarettes and combustible cigarettes. However, these results have to be validated in a larger cohortcomprised of users of e-cigarettes of multiple brands.

Supplemental Digital Content is available in the text., Objective— Use of alternative tobacco products including electronic cigarettes is rapidly rising. The wide variety of flavored tobacco products available is of great appeal to smokers and youth. The flavorings added to tobacco products have been deemed safe for ingestion, but the cardiovascular health effects are unknown. The purpose of this study was to examine the effect of 9 flavors on vascular endothelial cell function. Approach and Results— Freshly isolated endothelial cells from participants who use nonmenthol- or menthol-flavored tobacco cigarettes showed impaired A23187-stimulated nitric oxide production compared with endothelial cells from nonsmoking participants. Treatment of endothelial cells isolated from nonsmoking participants with either menthol (0.01 mmol/L) or eugenol (0.01 mmol/L) decreased A23187-stimulated nitric oxide production. To further evaluate the effects of flavoring compounds on endothelial cell phenotype, commercially available human aortic endothelial cells were incubated with vanillin, menthol, cinnamaldehyde, eugenol, dimethylpyrazine, diacetyl, isoamyl acetate, eucalyptol, and acetylpyrazine (0.1–100 mmol/L) for 90 minutes. Cell death, reactive oxygen species production, expression of the proinflammatory marker IL-6 (interleukin-6), and nitric oxide production were measured. Cell death and reactive oxygen species production were induced only at high concentrations unlikely to be achieved in vivo. Lower concentrations of selected flavors (vanillin, menthol, cinnamaldehyde, eugenol, and acetylpyridine) induced both inflammation and impaired A23187-stimulated nitric oxide production consistent with endothelial dysfunction. Conclusions— Our data suggest that short-term exposure of endothelial cells to flavoring compounds used in tobacco products have adverse effects on endothelial cell phenotype that may have relevance to cardiovascular toxicity.

Benzene is a ubiquitous environmental pollutant. Recent population-based studies suggest that benzene exposure is associated with an increased risk for cardiovascular disease. However, it is unclear whether benzene exposure by itself is sufficient to induce cardiovascular toxicity. We examined the effects of benzene inhalation (50 ppm, 6 h/day, 5 days/week, 6 weeks) or HEPA-filtered air exposure on the biomarkers of cardiovascular toxicity in male C57BL/6J mice. Benzene inhalation significantly increased the biomarkers of endothelial activation and injury including endothelial microparticles, activated endothelial microparticles, endothelial progenitor cell microparticles, lung endothelial microparticles, and activated lung and endothelial microparticles while having no effect on circulating levels of endothelial adhesion molecules, endothelial selectins, and biomarkers of angiogenesis. To understand how benzene may induce endothelial injury, we exposed human aortic endothelial cells to benzene metabolites. Of the metabolites tested, trans,trans-mucondialdehyde (10 μM, 18h) was the most toxic. It induced caspases-3, -7 and -9 (intrinsic pathway) activation and enhanced microparticle formation by 2.4-fold. Levels of platelet-leukocyte aggregates, platelet macroparticles, and a proportion of CD4+ and CD8+ T-cells were also significantly elevated in the blood of the benzene-exposed mice. We also found that benzene exposure increased the transcription of genes associated with endothelial cell and platelet activation in the liver; and induced inflammatory genes and suppressed cytochrome P450s in the lungs and the liver. Together, these data suggest that benzene exposure induces endothelial injury, enhances platelet activation and inflammatory processes; and circulatory levels of endothelial cell and platelet-derived microparticles and platelet-leukocyte aggregates are excellent biomarkers of cardiovascular toxicity of benzene.

Acrolein, an electrophilic α,β-unsaturated aldehyde, is present in foods and beverages, and is a product of incomplete combustion, and thus, reaches high ppm levels in tobacco smoke and structural fires. Exposure to acrolein is linked with cardiopulmonary toxicity and cardiovascular disease risk. The hypothesis of this study is the direct effects of acrolein in isolated murine blood vessels (aorta and superior mesenteric artery, SMA) are transient receptor potential ankyrin-1 (TRPA1) dependent. Using isometric myography, isolated aorta and SMA were exposed to increasing levels of acrolein. Acrolein inhibited phenylephrine (PE)-induced contractions (approximately 90%) in aorta and SMA of male and female mice in a concentration-dependent (0.01–100 μM) manner. The major metabolite of acrolein, 3-hydroxypropylmercapturic acid (3HPMA), also relaxed PE-precontracted SMA. As the SMA was 20× more sensitive to acrolein than aorta (SMA EC50 0.8 ± 0.2 μM; aorta EC50 > 29.4 ± 4.4 μM), the mechanisms of acrolein-induced relaxation were studied in SMA. The potency of acrolein-induced relaxation was inhibited significantly by: 1) mechanically-impaired endothelium; 2) Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME); 3) guanylyl cyclase (GC) inhibitor (ODQ); and, 4) a TRPA1 antagonist (A967079). TRPA1 positive immunofluorescence was present in the endothelium. Compared with other known TRPA1 agonists, including allyl isothiocyanate (AITC), cinnamaldehyde, crotonaldehyde, and formaldehyde, acrolein stimulated a more potent TRPA1-dependent relaxation. Acrolein, at high concentration [100 μM], induced tension oscillations (spasms) independent of TRPA1 in precontracted SMA but not in aorta. In conclusion, acrolein is vasorelaxant at low levels (physiological) yet vasotoxic at high levels (toxicological).

Exposure to fine particulate matter (PM2.5) air pollution is associated with quantitative deficits of circulating endothelial progenitor cells (EPCs) in humans. Related exposures of mice to concentrated ambient PM2.5 (CAP) likewise reduces levels of circulating EPCs and induces defects in their proliferation and angiogenic potential as well. These changes in EPC number or function are predictive of larger cardiovascular dysfunction. To identify global, PM2.5-dependent mRNA and miRNA expression changes that may contribute to these defects, we performed a transcriptomic analysis of cells isolated from exposed mice. Compared with control samples, we identified 122 upregulated genes and 44 downregulated genes in EPCs derived from CAP-exposed animals. Functions most impacted by these gene expression changes included regulation of cell movement, cell and tissue development, and cellular assembly and organization. With respect to miRNA changes, we found that 55 were upregulated while 53 were downregulated in EPCs from CAP-exposed mice. The top functions impacted by these miRNA changes included cell movement, cell death and survival, cellular development, and cell growth and proliferation. A subset of these mRNA and miRNA changes were confirmed by qRT-PCR, including some reciprocal relationships. These results suggest that PM2.5-induced changes in gene expression may contribute to EPC dysfunction and that such changes may contribute to the adverse cardiovascular outcomes of air pollution exposure.

Background: Exercise promotes metabolic remodeling in the heart, which is associated with physiological 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 physiological 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 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, in the recovered state following exercise adaptation, there was an increase in myocardial phosphofructokinase activity and glycolysis. In mice, cardiac-specific expression of a kinase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase transgene (Glyco Lo mice) lowered glycolytic rate and regulated the expression of genes known to promote cardiac growth. Hearts of Glyco Lo mice had larger myocytes, enhanced cardiac function, and higher capillary-to-myocyte ratios. Expression of phosphatase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase in the heart (Glyco Hi mice) increased glucose utilization and promoted a more pathological form of hypertrophy devoid of transcriptional activation of the physiological 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 physiological cardiac remodeling, and metabolic flexibility is important for maintaining mitochondrial health in the heart.

The mechanism for intermittent hypoxia (IH)-induced cardiomyopathy remains obscure. We reported the prevention of acute and chronic IH-induced cardiac damage by selective cardiac overexpression of metallothionein (MT). Herein we defined that MT-mediated protection from IH-cardiomyopathy is via activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a critical redox-balance controller in the body. For this, mice were exposed to IH for 3 days (acute) or 4 or 8 weeks (chronic). Cardiac Nrf2 and MT expression in response to IH were significantly increased acutely yet decreased chronically. Interestingly, cardiac overexpression (Nrf2-TG) or global deletion of the Nrf2 gene (Nrf2-KO) made mice highly resistant or highly susceptible, respectively, to IH-induced cardiomyopathy and MT expression. Mechanistically, 4-week IH exposure significantly decreased cardiac Nrf2 binding to the MT gene promoter, and thus, depressed both MT transcription and translation in WT mice but not Nrf2-TG mice. Likewise, cardiac MT overexpression prevented chronic IH-induced cardiomyopathy and down-regulation of Nrf2 likely via activation of a PI3K/Akt/GSK-3β/Fyn-dependent signaling pathway. These results reveal an integrated relationship between cardiac Nrf2 and MT expression in response to IH -- acute compensatory up-regulation followed by chronic down-regulation and cardiomyopathy. Cardiac overexpression of either Nrf2 or MT offered cardioprotection from IH via complicated PI3K/Akt/GSK3B/Fyn signaling. Potential therapeutics may target either Nrf2 or MT to prevent chronic IH-induced cardiomyopathy.

Lysine acetylation is involved in various biological processes and is considered a key reversible post-translational modification in the regulation of gene expression, enzyme activity, and subcellular localization. This post-translational modification is therefore highly relevant in the context of circadian biology, but its characterization on the proteome-wide scale and its circadian clock dependence are still poorly described. Here, we provide a comprehensive and rhythmic acetylome map of the mouse liver. Rhythmic acetylated proteins showed subcellular localization-specific phases that correlated with the related metabolites in the regulated pathways. Mitochondrial proteins were over-represented among the rhythmically acetylated proteins and were highly correlated with SIRT3-dependent deacetylation. SIRT3 activity being nicotinamide adenine dinucleotide (NAD)+ level-dependent, we show that NAD+ is orchestrated by both feeding rhythms and the circadian clock through the NAD+ salvage pathway but also via the nicotinamide riboside pathway. Hence, the diurnal acetylome relies on a functional circadian clock and affects important diurnal metabolic pathways in the mouse liver.

Exposure to tobacco smoke, which contains several harmful and potentially harmful constituents such as acrolein increases cardiovascular disease (CVD) risk. Although high acrolein levels induce pervasive cardiovascular injury, the effects of low-level exposure remain unknown and sensitive biomarkers of acrolein toxicity have not been identified. Identification of such biomarkers is essential to assess the toxicity of acrolein present at low levels in the ambient air or in new tobacco products such as e-cigarettes. Hence, we examined the systemic effects of chronic (12 weeks) acrolein exposure at concentrations similar to those found in tobacco smoke (0.5 or 1 ppm). Acrolein exposure in mice led to a 2- to 3-fold increase in its urinary metabolite 3-hydroxypropyl mercapturic acid (3-HPMA) with an attendant increase in pulmonary levels of the acrolein-metabolizing enzymes, glutathione S-transferase P and aldose reductase, as well as several Nrf2-regulated antioxidant proteins. Markers of pulmonary endoplasmic reticulum stress and inflammation were unchanged. Exposure to acrolein suppressed circulating levels of endothelial progenitor cells (EPCs) and specific leukocyte subsets (eg, GR-1+ cells, CD19+ B-cells, CD4+ T-cells; CD11b+ monocytes) whilst other subsets (eg, CD8+ cells, NK1.1+ cells, Ly6C+ monocytes) were unchanged. Chronic acrolein exposure did not affect systemic glucose tolerance, platelet–leukocyte aggregates or microparticles in blood. These findings suggest that circulating levels of EPCs and specific leukocyte populations are sensitive biomarkers of inhaled acrolein injury and that low-level (