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Alarmins are classified by their release from damaged or ruptured cells. Many alarmins have been found to increase vascular tone and oppose endothelium-dependent dilatation (EDD). Interleukin (IL)-33 plays a prominent role in lung injury and can be released during vascular injury and in chronic studies found to be cardioprotective. Our recent work has implicated IL-33 in acute vascular dysfunction following inhalation of engineered nanomaterials (ENM). However, the mechanisms linking IL-33 to vascular tone have not been interrogated. We therefore aimed to determine whether IL-33 directly influenced microvascular tone and endothelial function. Isolated feed arteries and in vivo arterioles from male and female Sprague-Dawley rats were used to determine direct vascular actions of IL-33. Mesenteric feed arteries and arterioles demonstrated reduced intraluminal diameters when treated with increasing concentrations of recombinant IL-33. IL-33 activated extracellular signal regulated kinase (ERK)1/2 of rat aortic smooth muscle cells but not phosphorylation of myosin light chain kinase. This suggested IL-33 may sensitize arterioles to Ca 2+ -mediated responses. Indeed, IL-33 augmented the myogenic- and phenylephrine-induced vasoconstriction. Additionally, incubation of arterioles with 1 ng IL-33 attenuated ACh-mediated EDD. Mechanistically, in human aortic endothelial cells, we demonstrate that IL-33-mediated ERK1/2 activation leads to inhibitory phosphorylation of serine 602 on endothelial nitric oxide synthase. Finally, we demonstrate that IL-33-ERK1/2 contributes to vascular tone following two known inducers of IL-33; ENM inhalation and the rupture endothelial cells. The present study provides novel evidence that IL-33 increases vascular tone via canonical ERK1/2 activation in microvascular smooth muscle and endothelium. Altogether, it is suggested IL-33 plays a critical role in microvascular homeostasis following barrier cell injury. KEY POINTS: Interleukin (IL)-33 causes a concentration-dependent reduction in feed artery diameter. IL-33 acts on vascular smooth muscle cells to augment Ca 2+ -mediated processes. IL-33 causes inhibitory phosphorylation of endothelial nitric oxide synthase and opposes endothelium-dependent dilatation. Engineered nanomaterial-induced lung injury and endothelial cell rupture in part act through IL-33 to mediate increased vascular tone., (© 2024 The Authors. The Journal of Physiology © 2024 The Physiological Society.)

Xanthine oxidase (XO) mediates vascular function. Chronic stress impairs cerebrovascular function and increases the risk of stroke and cognitive decline. Our study determined the role of XO on stress-induced cerebrovascular dysfunction and cognitive decline. We measured middle cerebral artery (MCA) function, free radical formation, and working memory in 6-month-old C57BL/6 mice who underwent 8 weeks of control conditions or unpredictable chronic mild stress (UCMS) with or without febuxostat (50 mg/L), a XO inhibitor. UCMS mice had an impaired MCA dilation to acetylcholine vs. controls (p < 0.0001), and increased total free radical formation, XOR protein levels, and hydrogen peroxide production in the liver compared to controls. UCMS increased hydrogen peroxide production in the brain and cerebrovasculature compared to controls. Working memory, using the y-maze test, was impaired (p < 0.05) in UCMS mice compared to control mice. However, blocking XO using febuxostat prevented the UCMS-induced impaired MCA response, while free radical production and hydrogen peroxide levels were similar to controls in the liver and brain of UCMS mice treated with febuxostat. Further, UCMS + Feb mice did not have a significant reduction in working memory. These data suggest that the cerebrovascular dysfunction associated with chronic stress may be driven by XO, which leads to a reduction in working memory.

Nano-titanium dioxide (nano-TiO 2 ) is a widely used nanomaterial found in several industrial and consumer products, including surface coatings, paints, sunscreens and cosmetics, among others. Studies have linked gestational exposure to nano-TiO 2 with negative maternal and fetal health outcomes. For example, maternal pulmonary exposure to nano-TiO 2 during gestation has been associated not only with maternal, but also fetal microvascular dysfunction in a rat model. One mediator of this altered vascular reactivity and inflammation is oxylipid signaling. Oxylipids are formed from dietary lipids through several enzyme-controlled pathways as well as through oxidation by reactive oxygen species. Oxylipids have been linked to control of vascular tone, inflammation, pain and other physiological and disease processes. In this study, we use a sensitive UPLC-MS/MS based analysis to probe the global oxylipid response in liver, lung, and placenta of pregnant rats exposed to nano-TiO 2 aerosols. Each organ presented distinct patterns in oxylipid signaling, as assessed by principal component and hierarchical clustering heatmap analysis. In general, pro-inflammatory mediators, such as 5-hydroxyeicosatetraenoic acid (1.6 fold change) were elevated in the liver, while in the lung, anti-inflammatory and pro-resolving mediators such as 17-hydroxy docosahexaenoic acid (1.4 fold change) were elevated. In the placenta the levels of oxylipid mediators were generally decreased, both inflammatory ( e.g. PGE 2 , 0.52 fold change) and anti-inflammatory ( e.g. Leukotriene B4, 0.49 fold change). This study, the first to quantitate the levels of these oxylipids simultaneously after nano-TiO 2 exposure, shows the complex interplay of pro- and anti-inflammatory mediators from multiple lipid classes and highlights the limitations of monitoring the levels of oxylipid mediators in isolation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The placenta plays a critical role in nutrient-waste exchange between the maternal and fetal circulations, thus functioning as an interface that profoundly impacts fetal growth and development. The placenta has long been considered an asexual organ, but, due to its embryonic origin it shares the same sex as the fetus. Exposures to toxicant such as diesel exhaust, have been shown to result in sexually dimorphic outcomes like decreased placental mass in exposed females. Therefore, we hypothesize that maternal nano-TiO 2 inhalation exposure during gestation alters placental hemodynamics in a sexually dimorphic manner. Pregnant Sprague-Dawley rats were exposed from gestational day 10-19 to nano-TiO 2 aerosols (12.17 ± 1.69 mg/m 3 ) or filtered air (sham-control). Dams were euthanized on GD20, and fetal tissue was collected based on fetal sex: whole placentas, placental junctional zone (JZ), and placental labyrinth zone (LZ). Fetal mass, placental mass, and placental zone percent areas were assessed for sex-based differences. Exposed fetal females were significantly smaller compared to their exposed male counterparts (2.65 ± 0.03 g vs 2.78 ± 0.04 g). Nano-TiO 2 exposed fetal females had a significantly decreased percent junctional zone area compared to the sham-control females (24.37 ± 1.30% vs 30.39 ± 1.54%). The percent labyrinth zone area was significantly increased for nano-TiO 2 females compared to sham-control females (75.63 ± 1.30% vs 69.61 ± 1.54%). Placental flow and hemodynamics were assessed with a variety of vasoactive substances. It was found that nano-TiO 2 exposed fetal females only had a significant decrease in outflow pressure in the presence of the thromboxane (TXA 2 ) mimetic, U46619, compared to sham-control fetal females (3.97 ± 1.30 mm Hg vs 9.10 ± 1.07 mm Hg) and nano-TiO 2 fetal males (9.96 ± 0.66 mm Hg). Maternal nano-TiO 2 inhalation exposure has a greater effect on fetal female mass, placental zone mass and area, and adversely impacts placental vasoreactivity. This may influence the female growth and development later in life, future studies need to further study the impact of maternal nano-TiO 2 inhalation exposure on zone specific mechanisms., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Griffith, Dunn, DeVallance, Schafner, Engles, Batchelor, Goldsmith, Wix, Hussain, Bowdridge and Nurkiewicz.)

Pregnancy requires rapid adaptations in the uterine microcirculation to support fetal development. Nanomaterial inhalation is associated with cardiovascular dysfunction, which may impair gestation. We have shown that maternal nano-titanium dioxide (nano-TiO2) inhalation impairs microvascular endothelial function in response to arachidonic acid and thromboxane (TXA2) mimetics. However, the mechanisms underpinning this process are unknown. Therefore, we hypothesize that maternal nano-TiO2 inhalation during gestation results in uterine microvascular prostacyclin (PGI2) and TXA2 dysfunction. Pregnant Sprague-Dawley rats were exposed from gestational day 10-19 to nano-TiO2 aerosols (12.17  ± 1.67 mg/m3) or filtered air (sham-control). Dams were euthanized on gestational day 20, and serum, uterine radial arterioles, implantation sites, and lungs were collected. Serum was assessed for PGI2 and TXA2 metabolites. TXB2, the stable TXA2 metabolite, was significantly decreased in nano-TiO2 exposed dams (597.3 ± 84.4 vs 667.6 ± 45.6 pg/ml), whereas no difference was observed for 6-keto-PGF1α, the stable PGI2 metabolite. Radial arteriole pressure myography revealed that nano-TiO2 exposure caused increased vasoconstriction to the TXA2 mimetic, U46619, compared with sham-controls (-41.3% ± 4.3% vs -16.8% ± 3.4%). Nano-TiO2 exposure diminished endothelium-dependent vasodilation to carbaprostacyclin, a PGI2 receptor agonist, compared with sham-controls (30.0% ± 9.0% vs 53.7% ± 6.0%). Maternal nano-TiO2 inhalation during gestation decreased nano-TiO2 female pup weight when compared with sham-control males (3.633 ± 0.064 vs 3.995 ± 0.124 g). Augmented TXA2 vasoconstriction and decreased PGI2 vasodilation may lead to decreased placental blood flow and compromise maternofetal exchange of waste and nutrients, which could ultimately impact fetal health outcomes., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Pregnancy is associated with many rapid biological adaptations that support healthy development of the growing fetus. One of which is critical to fetal health and development is the coordination between maternal liver derived substrates and vascular delivery. This crucial adaptation can be potentially derailed by inhalation of toxicants. Engineered nanomaterials (ENM) are commonly used in household and industrial products as well as in medicinal applications. As such, the potential risk of exposure remains a concern, especially during pregnancy. We have previously reported that ENM inhalation leads to upregulation in the production of oxidative species. Therefore, we aimed to determine if F0 dam maternal nano-TiO 2 inhalation exposure (exclusively) resulted in altered H 2 O 2 production capacity and changes in downstream redox pathways in the F0 dams and subsequent F1 pups. Additionally, we investigated whether this persisted into adulthood within the F1 generation and how this impacted F1 gestational outcomes and F2 fetal health and development. We hypothesized that maternal nano-TiO 2 inhalation exposure during gestation in the F0 dams would result in upregulated H 2 O 2 production in the F0 dams as well as her F1 offspring. Additionally, this toxicological insult would result in gestational vascular dysfunction in the F1 dams yielding smaller F2 generation pups., Results: Our results indicate upregulation of hepatic H 2 O 2 production capacity in F0 dams, F1 offspring at 8 weeks and F1 females at gestational day 20. H 2 O 2 production capacity was accompanied by a twofold increase in phosphorylation of the redox sensitive transcription factor NF-κB. In cell culture, naïve hepatocytes exposed to F1-nano-TiO 2 plasma increased H 2 O 2 production. Overnight exposure of these hepatocytes to F1 plasma increased H 2 O 2 production capacity in a partially NF-κB dependent manner. Pregnant F1- nano-TiO 2 females exhibited estrogen disruption (12.12 ± 3.1 pg/ml vs. 29.81 ± 8.8 pg/ml sham-control) and vascular dysfunction similar to their directly exposed mothers. F1-nano-TiO 2 uterine artery H 2 O 2 production capacity was also elevated twofold. Dysfunctional gestational outcomes in the F1-nano-TiO 2 dams resulted in smaller F1 (10.22 ± 0.6 pups vs. sham-controls 12.71 ± 0.96 pups) and F2 pups (4.93 ± 0.47 g vs. 5.78 ± 0.09 g sham-control pups), and fewer F1 male pups (4.38 ± 0.3 pups vs. 6.83 ± 0.84 sham-control pups)., Conclusion: In conclusion, this manuscript provides critical evidence of redox dysregulation across generations following maternal ENM inhalation. Furthermore, dysfunctional gestational outcomes are observed in the F1-nano-TiO 2 generation and impact the development of F2 offspring. In total, this data provides strong initial evidence that maternal ENM exposure has robust biological impacts that persists in at least two generations., (© 2022. The Author(s).)

Maternal inhalation exposure to engineered nanomaterials (ENM) has been associated with microvascular dysfunction and adverse cardiovascular responses. Pregnancy requires coordinated vascular adaptation and growth that are imperative for survival. Key events in pregnancy hallmark distinct periods of gestation such as implantation, spiral artery remodeling, placentation, and trophoblast invasion. Angiotensin II (Ang II) is a critical vasoactive mediator responsible for adaptations and is implicated in the pathology of preeclampsia. If perturbations occur during gestation, such as those caused by ENM inhalation exposure, then maternal-fetal health consequences may occur. Our study aimed to identify the period of gestation in which maternal microvascular functional and fetal health are most vulnerable. Additionally, we wanted to determine if Ang II sensitivity and receptor density is altered due to exposure. Dams were exposed to ENM aerosols (nano-titanium dioxide) during three gestational windows: early (EE, gestational day (GD) 2-6), mid (ME, GD 8-12) or late (LE, GD 15-19). Within the EE group dry pup mass decreased by 16.3% and uterine radial artery wall to lumen ratio (WLR) increased by 25.9%. Uterine radial artery response to Ang II sensitivity increased by 40.5% in the EE group. Ang II receptor density was altered in the EE and LE group with decreased levels of AT 2 R. We conclude that early gestational maternal inhalation exposures resulted in altered vascular anatomy and physiology. Exposure during this time-period results in altered vascular reactivity and changes to uterine radial artery WLR, leading to decreased perfusion to the fetus and resulting in lower pup mass., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Cigarette smoke (CS) is the most common risk factor for chronic obstructive pulmonary disease (COPD). The present study aimed to elucidate whether mtDNA is released upon CS exposure and is detected in the plasma of former smokers affected by COPD as a possible consequence of airway damage. We measured cell-free mtDNA (cf-mtDNA) and nuclear DNA (cf-nDNA) in COPD patient plasma and mouse serum with CS-induced emphysema. The plasma of patients with COPD and serum of mice with CS-induced emphysema showed increased cf-mtDNA levels. In cell culture, exposure to a sublethal dose of CSE decreased mitochondrial membrane potential, increased oxidative stress, dysregulated mitochondrial dynamics, and triggered mtDNA release in extracellular vesicles (EVs). Mitochondrial DNA release into EVs occurred concomitantly with increased expression of markers that associate with DNA damage responses, including DNase III, DNA-sensing receptors (cGAS and NLRP3), proinflammatory cytokines (IL-1β, IL-6, IL-8, IL-18, and CXCL2), and markers of senescence (p16 and p21); the majority of the responses are also triggered by cytosolic DNA delivery in vitro . Exposure to a lethal CSE dose preferentially induced mtDNA and nDNA release in the cell debris. Collectively, the results of this study associate markers of mitochondrial stress, inflammation, and senescence with mtDNA release induced by CSE exposure. Because high cf-mtDNA is detected in the plasma of COPD patients and serum of mice with emphysema, our findings support the future study of cf-mtDNA as a marker of mitochondrial stress in response to CS exposure and COPD pathology.

Significance: Highly prevalent in Western cultures, obesity, metabolic syndrome, and diabetes increase the risk of cardiovascular morbidity and mortality and cost health care systems billions of dollars annually. At the cellular level, obesity, metabolic syndrome, and diabetes are associated with increased production of reactive oxygen species (ROS). Increased levels of ROS production in key organ systems such as adipose tissue, skeletal muscle, and the vasculature cause disruption of tissue homeostasis, leading to increased morbidity and risk of mortality. More specifically, growing evidence implicates the nicotinamide adenine dinucleotide phosphate oxidase (NOX) enzymes in these pathologies through impairment of insulin signaling, inflammation, and vascular dysfunction. The NOX family of enzymes is a major driver of redox signaling through its production of superoxide anion, hydrogen peroxide, and attendant downstream metabolites acting on redox-sensitive signaling molecules. Recent Advances: The primary goal of this review is to highlight recent advances and survey our present understanding of cell-specific NOX enzyme contributions to metabolic diseases. Critical Issues: However, due to the short half-lives of individual ROS and/or cellular defense systems, radii of ROS diffusion are commonly short, often restricting redox signaling and oxidant stress to localized events. Thus, special emphasis should be placed on cell type and subcellular location of NOX enzymes to better understand their role in the pathophysiology of metabolic diseases. Future Directions: We discuss the targeting of NOX enzymes as potential therapy and bring to light potential emerging areas of NOX research, microparticles and epigenetics, in the context of metabolic disease.

The aim of the study was to determine the effects of exercise training on improving the thoracic perivascular adipose tissue (tPVAT) phenotype (inflammation, oxidative stress, and proteasome function) in metabolic syndrome and its subsequent actions on aortic function., Methods: Lean and obese (model of metabolic syndrome) Zucker rats (n=8/group) underwent 8-weeks of control conditions or treadmill exercise (70% of max speed, 1 h/day, 5 days/week). At the end of the intervention, the tPVAT was removed and conditioned media was made. The cleaned aorta was attached to a force transducer to assess endothelium-dependent and independent dilation in the presence or absence of tPVAT-conditioned media. tPVAT gene expression, inflammatory /oxidative phenotype, and proteasome function were assessed., Results: The main findings were that Ex induced: (1) a beige-like, anti-inflammatory tPVAT phenotype; (2) a greater abundance of • NO in tPVAT; (3) a reduction in tPVAT oxidant production; and (4) an improved tPVAT proteasome function. Regarding aortic function, endothelium-dependent dilation was greater in exercised lean and obese groups vs. controls (p < 0.05). Lean control tPVAT improved aortic relaxation, whereas obese control tPVAT decreased aortic relaxation. In contrast, the obese Ex-tPVAT increased aortic dilation, whereas the lean Ex-tPVAT did not affect aortic dilation., Conclusion: Overall, exercise had the most dramatic impact on the obese tPVAT reflecting a change towards an environment with less oxidant load, less inflammation and improved proteasome function. Such beneficial changes to the tPVAT micro-environment with exercise likely played a significant role in mediating the improvement in aortic function in metabolic syndrome following 8 weeks of exercise., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

First described as essential to the phagocytic activity of leukocytes, Nox2-derived ROS have emerged as mediators of a range of cellular and tissue responses across species from salubrious to deleterious consequences. Knowledge of their role in inflammation is limited, however. We postulated that TNFα-induced endothelial reactive oxygen species (ROS) generation and pro-inflammatory signaling would be ameliorated by targeting Nox2. Herein, we in silico-modelled two first-in-class Nox2 inhibitors developed in our laboratory, explored their cellular mechanism of action and tested their efficacy in in vitro and mouse in vivo models of inflammation. Our data show that these inhibitors (CPP11G and CPP11H) disrupted canonical Nox2 organizing factor, p47 phox , translocation to Nox2 in the plasma membrane; and abolished ROS production, markedly attenuated stress-responsive MAPK signaling and downstream AP-1 and NFκB nuclear translocation in human cells. Consequently, cell adhesion molecule expression and monocyte adherence were significantly inhibited by both inhibitors. In vivo, TNFα-induced ROS and inflammation were ameliorated by targeted Nox2 inhibition, which, in turn, improved hind-limb blood flow. These studies identify a proximal role for Nox2 in propagated inflammatory signaling and support therapeutic value of Nox2 inhibitors in inflammatory disease., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

Pulmonary arterial hypertension (PAH) is a complex degenerative disorder marked by aberrant vascular remodeling associated with hyperproliferation and migration of endothelial cells (ECs). Previous reports implicated bone morphogenetic protein antagonist Gremlin 1 in this process; however, little is known of the molecular mechanisms involved. The current study was designed to test whether redox signaling initiated by NADPH oxidase 1 (Nox1) could promote transcription factor CREB activation by redox factor 1 (Ref-1), transactivation of Gremlin1 transcription, EC migration, and proliferation. Human pulmonary arterial EC (HPAECs) exposed in vitro to hypoxia to recapitulate PAH signaling displayed induced Nox1 expression, reactive oxygen species (ROS) production, PKA activity, CREB phosphorylation, and CREB:CRE motif binding. These responses were abrogated by selective Nox1 inhibitor NoxA1ds and/or siRNA Nox1. Nox1-activated CREB migrated to the nucleus and bound to Ref-1 leading to CREB:CRE binding and Gremlin1 transcription. CHiP assay and CREB gene-silencing illustrated that CREB is pivotal for hypoxia-induced Gremlin1, which, in turn, stimulates EC proliferation and migration. In vivo, participation of Nox1, CREB, and Gremlin1, as well as CREB:CRE binding was corroborated in a rat PAH model. Activation of a previously unidentified Nox1-PKA-CREB/Ref-1 signaling pathway in pulmonary endothelial cells leads to Gremlin1 transactivation, proliferation and migration. These findings reveal a new signaling pathway by which Nox1 via induction of CREB and Gremlin1 signaling contributes to vascular remodeling and provide preclinical indication of its significance in PAH., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

New Findings: What is the central question of this study? How does chronic stress impact cerebrovascular function and does metabolic syndrome accelerate the cerebrovascular adaptations to stress? What role does exercise training have in preventing cerebrovascular changes to stress and metabolic syndrome? What is the main finding and its importance? Stressful conditions lead to pathological adaptations of the cerebrovasculature via an oxidative nitric oxide pathway, and the presence of metabolic syndrome produces a greater susceptibility to stress-induced cerebrovascular dysfunction. The results also provide insight into the mechanisms that may contribute to the influence of stress and the role of exercise in preventing the negative actions of stress on cerebrovascular function and structure., Abstract: Chronic unresolvable stress leads to the development of depression and cardiovascular disease. There is a high prevalence of depression with the metabolic syndrome (MetS), but to what extent the MetS concurrent with psychological stress affects cerebrovascular function is unknown. We investigated the differential effect of MetS on cerebrovascular structure/function in rats (16-17 weeks old) following 8 weeks of unpredictable chronic mild stress (UCMS) and whether exercise training could limit any cerebrovascular dysfunction. In healthy lean Zucker rats (LZR), UCMS decreased (28%, P < 0.05) ex vivo middle cerebral artery (MCA) endothelium-dependent dilatation (EDD), but changes in MCA remodelling and stiffness were not evident, though cerebral microvessel density (MVD) decreased (30%, P < 0.05). The presence of UCMS and MetS (obese Zucker rats; OZR) decreased MCA EDD (35%, P < 0.05) and dilatation to sodium nitroprusside (20%, P < 0.05), while MCA stiffness increased and cerebral MVD decreased (31%, P < 0.05), which were linked to reduced nitric oxide and increased oxidative levels. Aerobic exercise prevented UCMS impairments in MCA function and MVD in LZR, and partly restored MCA function, stiffness and MVD in OZR. Our data suggest that the benefits of exercise with UCMS were due to a reduction in oxidative stress and increased production of nitric oxide in the cerebral vessels. In conclusion, UCMS significantly impaired MCA structure and function, but the effects of UCMS were more substantial in OZR vs. LZR. Importantly, aerobic exercise when combined with UCMS prevented the MCA dysfunction through subtle shifts in nitric oxide and oxidative stress in the cerebral microvasculature., (© 2018 The Authors. Experimental Physiology © 2018 The Physiological Society.)

New Findings: What is the central question of this study? Tumour necrosis factor-α (TNFα) has been shown to impair vascular function, but the impact of thoracic aorta perivascular adipose tissue (tPVAT)-derived TNFα on tPVAT and aortic function in metabolic syndrome is unknown. What is the main finding and its importance? Release of TNFα by tPVAT causes production of reactive oxygen species in tPVAT through activation of an NADPH-oxidase 2 (NOX2)-dependent pathway, activates production of aortic reactive oxygen species and mediates aortic stiffness, potentially through matrix metalloproteinase 9 activity. Neutralization of TNFα and/or inhibition of NOX2 blocks the tPVAT-induced impairment of aortic function. These data partly implicate tPVAT NOX2 and TNFα in mediating the vascular pathology of metabolic syndrome., Abstract: Perivascular adipose tissue (PVAT) is recognized for its vasoactive effects, but it is unclear how metabolic syndrome impacts thoracic aorta (t)PVAT and the subsequent effect on functional and structural aortic stiffness. Thoracic aorta and tPVAT were removed from 16- to 17-week-old lean (LZR, n = 16) and obese Zucker rats (OZR, n = 16). The OZR presented with aortic endothelial dysfunction, assessed by wire myography, and increased aortic stiffness, assessed by elastic modulus. The OZR tPVAT exudate further exacerbated the endothelial dysfunction, reducing nitric oxide and endothelium-dependent relaxation (P < 0.05). Additionally, OZR tPVAT exudate had increased MMP9 activity (P < 0.05) and further increased the elastic modulus of the aorta after 72 h of co-culture (P < 0.05). We found that the observed aortic dysfunction caused by OZR tPVAT was mediated through increased production and release of tumour necrosis factor-α (TNFα; P < 0.01), which was dependent on tPVAT NADPH-oxidase 2 (NOX2) activity. The OZR tPVAT release of reactive oxygen species and subsequent aortic dysfunction were inhibited by TNFα neutralization and/or inhibition of NOX2. Additionally, we found that OZR tPVAT had reduced activity of the active sites of the 20S proteasome (P < 0.05) and reduced superoxide dismutase activity (P < 0.01). In conclusion, metabolic syndrome causes tPVAT dysfunction through an interplay between TNFα and NOX2 that leads to tPVAT-mediated aortic stiffness by activation of aortic reactive oxygen species and increased MMP9 activity., (© 2018 The Authors. Experimental Physiology © 2018 The Physiological Society.)

Proponents for electronic cigarettes (E-cigs) claim that they are a safe alternative to tobacco-based cigarettes; however, little is known about the long-term effects of exposure to E-cig vapor on vascular function. The purpose of this study was to determine the cardiovascular consequences of chronic E-cig exposure. Female mice (C57BL/6 background strain) were randomly assigned to chronic daily exposure to E-cig vapor, standard (3R4F reference) cigarette smoke, or filtered air ( n = 15/group). Respective whole body exposures consisted of four 1-h-exposure time blocks, separated by 30-min intervals of fresh air breaks, resulting in intermittent daily exposure for a total of 4 h/day, 5 days/wk for 8 mo. Noninvasive ultrasonography was used to assess cardiac function and aortic arterial stiffness (AS), measured as pulse wave velocity, at three times points (before, during, and after chronic exposure). Upon completion of the 8-mo exposure, ex vivo wire tension myography and force transduction were used to measure changes in thoracic aortic tension in response to vasoactive-inducing compounds. AS increased 2.5- and 2.8-fold in E-cig- and 3R4F-exposed mice, respectively, compared with air-exposed control mice ( P < 0.05). The maximal aortic relaxation to methacholine was 24% and 33% lower in E-cig- and 3R4F-exposed mice, respectively, than in controls ( P < 0.05). No differences were noted in sodium nitroprusside dilation between the groups. 3R4F exposure altered cardiac function by reducing fractional shortening and ejection fraction after 8 mo ( P < 0.05). A similar, although not statistically significant, tendency was also observed with E-cig exposure ( P < 0.10). Histological and respiratory function data support emphysema-associated changes in 3R4F-exposed, but not E-cig-exposed, mice. Chronic exposure to E-cig vapor accelerates AS, significantly impairs aortic endothelial function, and may lead to impaired cardiac function. The clinical implication from this study is that chronic use of E-cigs, even at relatively low exposure levels, induces cardiovascular dysfunction. NEW & NOTEWORTHY Electronic cigarettes (E-cigs) are marketed as safe, but there has been insufficient long-term exposure to humans to justify these claims. This is the first study to report the long-term in vivo vascular consequences of 8 mo of exposure to E-cig vapor in mice (equivalent to ~25 yr of exposure in humans). We report that E-cig exposure increases arterial stiffness and impairs normal vascular reactivity responses, similar to other risk factors, including cigarette smoking, which contribute to the development of cardiovascular disease.

Acute and chronic stress have been reported to have differing effects on physical activity in rodents, but no study has examined a chronic stress protocol that incorporates stressors often experienced by rodents throughout a day. To examine this, the effects of the Unpredictable Chronic Mild Stress (UCMS) protocol on voluntary running wheel activity at multiple time points, and/or in response to acute removal of chronic stress was determined. Twenty male Balb/c mice were given access and accustomed to running wheels for 4 weeks, after which they were randomized into 2 groups; exercise (EX, n = 10) and exercise with chronic stress using a modified UCMS protocol for 7 hours/day (8:00 a.m.-3:00p.m.), 5 days/week for 8 weeks (EXS, n = 10). All mice were given access to running wheels from approximately 3:30 p.m. to 7:30 a.m. during the weekday, however during weekends mice had full-time access to running wheels (a time period of no stress for the EXS group). Daily wheel running distance and time were recorded. The average running distance, running time, and work each weekday was significantly lower in EXS compared to EX mice, however, the largest effect was seen during week one. Voluntary wheel running deceased in all mice with increasing age; the pattern of decline appeared to be similar between groups. During the weekend (when no stress was applied), EXS maintained higher distance compared to EX, as well as higher daily distance, time, and work compared to their weekday values. These results indicate that mild chronic stress reduces total spontaneous wheel running in mice during the first week of the daily stress induction and maintains this reduced level for up to 8 consecutive weeks. However, following five days of UCMS, voluntary running wheel activity rebounds within 2-3 days.

The metabolic syndrome (MetS) is highly prevalent in the North American population and is associated with increased risk for development of cerebrovascular disease. This study determined the structural and functional changes in the middle cerebral arteries (MCA) during the progression of MetS and the effects of chronic pharmacological interventions on mitigating vascular alterations in obese Zucker rats (OZR), a translationally relevant model of MetS. The reactivity and wall mechanics of ex vivo pressurized MCA from lean Zucker rats (LZR) and OZR were determined at 7-8, 12-13, and 16-17 wk of age under control conditions and following chronic treatment with pharmacological agents targeting specific systemic pathologies. With increasing age, control OZR demonstrated reduced nitric oxide bioavailability, impaired dilator (acetylcholine) reactivity, elevated myogenic properties, structural narrowing, and wall stiffening compared with LZR. Antihypertensive therapy (e.g., captopril or hydralazine) starting at 7-8 wk of age blunted the progression of arterial stiffening compared with OZR controls, while treatments that reduced inflammation and oxidative stress (e.g., atorvastatin, rosiglitazone, and captopril) improved NO bioavailability and vascular reactivity compared with OZR controls and had mixed effects on structural remodeling. These data identify specific functional and structural cerebral adaptations that limit cerebrovascular blood flow in MetS patients, contributing to increased risk of cognitive decline, cerebral hypoperfusion, and ischemic stroke; however, these pathological adaptations could potentially be blunted if treated early in the progression of MetS., (Copyright © 2015 the American Physiological Society.)

Purpose: The metabolic syndrome (MetS) is associated with threefold increased risk of cardiovascular (CV) morbidity and mortality, which is partly due to a blunted CV reserve capacity, reflected by a reduced peak exercise left ventricular (LV) contractility and aerobic capacity and a blunted peak arterial-ventricular coupling. To date, no study has examined whether aerobic exercise training in MetS can reverse peak exercise CV dysfunction. Furthermore, examining how exercise training alters CV function in a group of individuals with MetS before the development of diabetes and/or overt CV disease can provide insights into whether some of the pathophysiological CV changes can be delayed/reversed, lowering their CV risk. The objective of this study was to examine the effects of 8 wk of aerobic exercise training in individuals with MetS on resting and peak exercise CV function., Methods: Twenty participants with MetS underwent either 8 wk of aerobic exercise training (MetS-ExT, n = 10) or remained sedentary (MetS-NonT, n = 10) during this period. Resting and peak exercise CV function was characterized using Doppler echocardiography and gas exchange., Results: Exercise training did not alter resting LV diastolic or systolic function and arterial-ventricular coupling in MetS. In contrast, at peak exercise, an increase in LV contractility (40%, P < 0.01), cardiac output (28%, P < 0.05), and aerobic capacity (20%, P < 0.01), but a reduction in vascular resistance (30%, P < 0.05) and arterial-ventricular coupling (27%, P < 0.01), were noted in the MetS-ExT but not in the MetS-NonT group. Furthermore, an improvement in lifetime risk score was also noted in the MetS-ExT group., Conclusions: These findings have clinical importance because they provide insight that some of the pathophysiological changes associated with MetS can be improved and can lower the risk of CV disease.

The metabolic syndrome (MetS) is associated with a threefold increase risk of cardiovascular disease (CVD) mortality partly due to increased arterial stiffening. We compared the effects of aerobic exercise training on arterial stiffening/mechanics in MetS subjects without overt CVD or type 2 diabetes. MetS and healthy control (Con) subjects underwent 8 wk of exercise training (ExT; 11 MetS and 11 Con) or remained inactive (11 MetS and 10 Con). The following measures were performed pre- and postintervention: radial pulse wave analysis (applanation tonometry) was used to measure augmentation pressure and index, central pressures, and an estimate of myocardial efficiency; arterial stiffness was assessed from carotid-femoral pulse-wave velocity (cfPWV, applanation tonometry); carotid thickness was assessed from B-mode ultrasound; and peak aerobic capacity (gas exchange) was performed in the seated position. Plasma matrix metalloproteinases (MMP) and CVD risk (Framingham risk score) were also assessed. cfPWV was reduced (P < 0.05) in MetS-ExT subjects (7.9 ± 0.6 to 7.2 ± 0.4 m/s) and Con-ExT (6.6 ± 1.8 to 5.6 ± 1.6 m/s). Exercise training reduced (P < 0.05) central systolic pressure (116 ± 5 to 110 ± 4 mmHg), augmentation pressure (9 ± 1 to 7 ± 1 mmHg), augmentation index (19 ± 3 to 15 ± 4%), and improved myocardial efficiency (155 ± 8 to 168 ± 9), but only in the MetS group. Aerobic capacity increased (P < 0.05) in MetS-ExT (16.6 ± 1.0 to 19.9 ± 1.0) and Con-ExT subjects (23.8 ± 1.6 to 26.3 ± 1.6). MMP-1 and -7 were correlated with cfPWV, and both MMP-1 and -7 were reduced post-ExT in MetS subjects. These findings suggest that some of the pathophysiological changes associated with MetS can be improved after aerobic exercise training, thereby lowering their cardiovascular risk., (Copyright © 2014 the American Physiological Society.)