Endothelial dysfunction is a predictor for cardiovascular disease. Pre-clinical data suggest longstanding cardiovascular and cerebrovascular dysfunction occurs in offspring with perinatal electronic ...cigarette (Ecig) exposure. Further, direct use of Ecigs increases reactive oxygen species and impairs cerebrovascular function, but the combined effect of direct use in offspring with a history of perinatal exposure (i.e. double-hit condition) is not known. We tested the hypothesis that offspring with double-hit Ecig exposure will lead to greater cerebrovascular and neurocognitive dysfunction compared to in utero exposure only. Male and female offspring were obtained from time-mated Sprague Dawley female rats exposed to air (n=5 dams) or Ecig exposed (n=5 dams) and studied at either 3- or 6-months after birth. Ecig exposure for double-hit offspring began at 1-month before the timepoints and lasted 4-weeks (5-days/week with 90-min exposure/day). We found double-hit offspring (Ecig:Ecig=exposure dam:offspring) sustained further blunted MCA reactivity, increased severity of neuronal damage, and increased interactions of astrocytes and endothelial cells compared to offspring with maternal (Ecig:Air) or direct (Air:Ecig) exposure only. Circulating extracellular vesicles (EVs) were increased, while SIRT1 was decreased, in all Ecig exposed groups compared to controls (Air:Air), with Ecig:Ecig group showing the greatest respective change for each. Electron paramagnetic resonance spectroscopy revealed oxidative stress was the highest in the plasma of Ecig:Ecig group(p<0.05) than the other groups. These data show that a double-hit exposure in adolescent or adult offspring results in a greater decline in cerebrovascular function, biomarkers of neuronal dysfunction, and increased circulation of EVs compared to a single-hit exposure.
Obesity is driven by an imbalance between caloric intake and energy expenditure, causing excessive storage of triglycerides in adipose tissue at different sites around the body. Increased visceral ...adipose tissue (VAT) is associated with diabetes, while pericardial adipose tissue (PAT) is associated with cardiac pathology. Adipose tissue can expand either through cellular hypertrophy or hyperplasia, with the former correlating with decreased metabolic health in obesity. The aim of this study was to determine how VAT and PAT remodel in response to obesity, stress, and exercise. Here we have used the male obese Zucker rats, which carries two recessive fa alleles that result in the development of hyperphagia with reduced energy expenditure, resulting in morbid obesity and leptin resistance. At 9 weeks of age, a group of lean (Fa/Fa or Fa/fa) Zucker rats (LZR) and obese (fa/fa) Zucker rats (OZR) were treated with unpredictable chronic mild stress or exercise for 8 weeks. To determine the phenotype for PAT and VAT, tissue cellularity and gene expression were analyzed. Finally, leptin signaling was investigated further using cultured 3T3‐derived adipocytes. Tissue cellularity was determined following hematoxylin and eosin (H&E) staining, while qPCR was used to examine gene expression. PAT adipocytes were significantly smaller than those from VAT and had a more beige‐like appearance in both LZR and OZR. In the OZR group, VAT adipocyte cell size increased significantly compared with LZR, while PAT showed no difference. Exercise and stress resulted in a significant reduction in VAT cellularity in OZR, while PAT showed no change. This suggests that PAT cellularity does not remodel significantly compared with VAT. These data indicate that the extracellular matrix of PAT is able to remodel more readily than in VAT. In the LZR group, exercise increased insulin receptor substrate 1 (IRS1) in PAT but was decreased in the OZR group. In VAT, exercise decreased IRS1 in LZR, while increasing it in OZR. This suggests that in obesity, VAT is more responsive to exercise and subsequently becomes less insulin resistant compared with PAT. Stress increased PPAR‐γ expression in the VAT but decreased it in the PAT in the OZR group. This suggests that in obesity, stress increases adipogenesis more significantly in the VAT compared with PAT. To understand the role of leptin signaling in adipose tissue remodeling mechanistically, JAK2 autophosphorylation was inhibited using 5 μM 1,2,3,4,5,6‐hexabromocyclohexane (Hex) in cultured 3T3‐derived adipocytes. Palmitate treatment was used to induce cellular hypertrophy. Hex blocked adipocyte hypertrophy in response to palmitate treatment but not the increase in lipid droplet size. These data suggest that leptin signaling is necessary for adipocyte cell remodeling, and its absence induces whitening. Taken together, our data suggest that leptin signaling is necessary for adipocyte remodeling in response to obesity, exercise, and psychosocial stress.
CD163 is a scavenger receptor expressed on innate immune cell populations which can be shed from the plasma membrane via the metalloprotease ADAM17 to generate a soluble peptide with ...lympho-inhibitory properties. The purpose of this study was to investigate CD163 as a possible effector of stroke-induced adaptive immune system suppression. Liquid biopsies were collected from ischemic stroke patients (n = 39), neurologically asymptomatic controls (n = 20), and stroke mimics (n = 20) within 24 hours of symptom onset. Peripheral blood ADAM17 activity and soluble CD163 levels were elevated in stroke patients relative to non-stroke control groups, and negatively associated with post-stroke lymphocyte counts. Subsequent in vitro experiments suggested that this stroke-induced elevation in circulating soluble CD163 likely originates from activated monocytic cells, as serum from stroke patients stimulated ADAM17-dependant CD163 shedding from healthy donor-derived monocytes. Additional in vitro experiments demonstrated that stroke-induced elevations in circulating soluble CD163 can elicit direct suppressive effects on the adaptive immune system, as serum from stroke patients inhibited the proliferation of healthy donor-derived lymphocytes, an effect which was attenuated following serum CD163 depletion. Collectively, these observations provide novel evidence that the innate immune system employs protective mechanisms aimed at mitigating the risk of post-stroke autoimmune complications driven by adaptive immune system overactivation, and that CD163 is key mediator of this phenomenon.
Vascular contributions to cognitive impairment and dementia are a key pathology associated with Alzheimer’s disease (AD). Past work in our lab has shown that chronic stress induces cerebrovascular ...dysfunction due to a pro‐oxidative environment while epidemiological studies suggest a link between chronic stress and dementia. With this in mind, we tested the hypothesis that chronic stress accelerates the vascular pathology associated with AD potentially via the xanthine oxidase pathway.
Here, we utilized a triple transgenic mouse model of AD (3xTg AD) combined with our unpredicted chronic mild stress paradigm (UCMS) and a xanthine oxidase inhibitor, Febuxostat, to examine middle cerebral artery (MCA) function. Beginning at 4 months of age all mice underwent the UCMS paradigm for 8 weeks total while a subset of mice were given Febuxostat treated water (50mg/L). Mice were either euthanized immediately following the 8 weeks of UCMS (at 6 months‐of‐age) or euthanized 3 months post‐UCMS (at 9 months‐of‐age). Following euthanasia, the MCA’s were removed and positioned in a pressurized myobath. The MCA was exposed to increasing concentrations of acetylcholine (ACh; 10‐9M to 10‐4M), phenylephrine (PE; 10‐9M to 10‐4M), and sodium nitroprusside (SNP; 10‐9M to 10‐4M).
At 6 months‐of‐age, AD mice displayed impaired MCA dilation to ACh compared to WT control mice (8.2±1.4mm to 17.5±2.1mm, respectively; p<0.05). WT and AD mice that underwent UCMS displayed similar response to ACh compared to AD control mice (8.25±0.3mm and 7.125±1mm to 8.2±1.4mm, respectively). Treatment with Febuxostat prevented MCA dysfunction in AD control mice, WT UCMS mice, and AD UCMS mice (8.2±1.4mm vs 17.1±1mm, 8.25±0.3mm vs 18.25±1.1mm, 7.1±1mm vs 17.2±0.9mm, respectively; p<0.05). No differences were found between groups in the PE or SNP response. Interestingly, at 9 months‐of‐age, the majority of these trends persisted with the one exception being a compounded impairment in the AD UCMS group compared to both AD control or WT UCMS mice (3.5±1.2mm vs 8.5±1mm, and 9.3±2.2mm, respectively; p<0.05).
Overall, these data suggest that chronic stress does accelerate the cerebrovascular pathology associated with AD and potentially via a pro‐oxidative state driven by activation of the xanthine oxidase pathway.
Our group recently identified 16 genes whose peripheral blood expression levels are differentially regulated in acute ischemic stroke. The purpose of this study was to determine whether the early ...expression levels of any of these 16 genes are predictive for post-stroke blood brain barrier (BBB) disruption. Transcriptional expression levels of candidate genes were measured in peripheral blood sampled from ischemic stroke patients at emergency department admission, and BBB permeability was assessed at 24 hour follow up via perfusion-weighted imaging. Early heightened expression levels of AKAP7, a gene encoding a protein kinase A-binding scaffolding molecule, were significantly associated with BBB disruption 24 hours post-hospital admission. We then determined that AKAP7 is predominantly expressed by lymphocytes in peripheral blood, and strongly co-expressed with ITGA3, a gene encoding the adhesion molecule integrin alpha 3. Subsequent in vitro experiments revealed that heightened expression of AKAP7 and ITGA3 in primary human lymphocytes is associated with a highly adherent phenotype. Collectively, our results suggest that AKAP7 expression levels may have clinical utility as a prognostic biomarker for post-stroke BBB complications, and are likely elevated early in patients who later develop post-stroke BBB disruption due to the presence of an invasive lymphocyte population in the peripheral blood.
Age is the dominant risk factor for cardiovascular diseases. Understanding the coupling between the left ventricle (LV) and arterial system, termed arterial-ventricular coupling (E(A)/E(LV)), ...provides important mechanistic insights into the complex cardiovascular system and its changes with aging in the absence and presence of disease. E(A)/E(LV) can be indexed by the ratio of effective arterial elastance (E(A); a measure of the net arterial load exerted on the LV) to left ventricular end-systolic elastance (E(LV); a load-independent measure of left ventricular chamber performance). Age-associated alterations in arterial structure and function, including diameter, wall thickness, wall stiffness, and endothelial dysfunction, contribute to a gradual increase in resting E(A) with age. Remarkably there is a corresponding increase in resting E(LV) with age, due to alterations to LV remodeling (loss in myocyte number, increased collagen) and function. These age-adaptations at rest likely occur, at least, in response to the age-associated increase in E(A) and ensure that E(A)/E(LV) is closely maintained within a narrow range, allowing for optimal energetic efficiency at the expense of mechanical efficacy. This optimal coupling at rest is also maintained when aging is accompanied by the presence of hypertension, and obesity, despite further increases in E(A) and E(LV) in these conditions. In contrast, in heart failure patients with either reduced or preserved ejection fraction, E(A)/E(LV) at rest is impaired. During dynamic exercise, E(A)/E(LV) decreases, due to an acute mismatch between the arterial and ventricular systems as E(LV) increases disproportionate compared to E(A) (≈200 vs. 40%), to ensure that sufficient cardiac performance is achieved to meet the increased energetic requirements of the body. However, with advancing age the reduction in E(A)/E(LV) during acute maximal exercise is blunted, due to a blunted increase E(LV). This impaired E(A)/E(LV) is further amplified in the presence of disease, and may explain, in part, the reduced cardiovascular functional capacity with age and disease. Thus, although increased stiffness of the arteries itself has important physiological and clinical relevance, such changes also have major implications on the heart, and vice versa, and the manner in the way they interact has important ramifications on cardiovascular function both at rest and during exercise. Examination of the alterations in arterial-ventricular coupling with aging and disease can yield mechanistic insights into the pathophysiology of these conditions and increase the effectiveness of current therapeutic interventions.
The study of vascular function across conditions has been an intensive area of investigation for many years. While these efforts have revealed many factors contributing to vascular health, challenges ...remain for integrating results across research groups, animal models, and experimental conditions to understand integrated vascular function. As such, the insights attained in clinical/population research from linking datasets, have not been fully realized in the basic sciences, thus frustrating advanced analytics and complex modeling. To achieve comparable advances, we must address the conceptual challenge of defining/measuring integrated vascular function and the technical challenge of combining data across conditions, models, and groups. Here, we describe an approach to establish and validate a composite metric of vascular function by comparing parameters of vascular function in metabolic disease (the obese Zucker rat) to the same parameters in age-matched, "healthy" conditions, resulting in a common outcome measure which we term the vascular health index (VHI). VHI allows for the integration of datasets, thus expanding sample size and permitting advanced modeling to gain insight into the development of peripheral and cerebral vascular dysfunction. Markers of vascular reactivity, vascular wall mechanics, and microvascular network density are integrated in the VHI. We provide a detailed presentation of the development of the VHI and provide multiple measures to assess face, content, criterion, and discriminant validity of the metric. Our results demonstrate how the VHI captures multiple indices of dysfunction in the skeletal muscle and cerebral vasculature with metabolic disease and provide context for an integrated understanding of vascular health under challenged conditions.
Adipose tissue and arterial dysfunction are common in the obese state. Perivascular adipose tissue (PVAT) plays an important role in mediating arterial health, and with obesity, the PVAT dysfunction ...negatively affects arterial health. Exercise training exerts direct and beneficial effects on PVAT, providing an additional and novel pathway by which exercise can improve arterial health in diseased populations.
Highlights • Expression prolife data suggest stroke involves a complex inflammatory response. • Neutrophil and lymphocyte ratio may be a useful biomarker for stroke outcome. • Arginase from ...neutrophil may play a role in stroke-associated immunosuppression.
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