Age-associated Cardiovascular Diseases Research Articles

Cardiovascular aging: spotlight on mitochondria.

Mitochondria are cellular organelles critical for ATP production and are particularly relevant to cardiovascular diseases including heart failure, atherosclerosis, ischemia-reperfusion injury, and cardiomyopathies. With advancing age, even in the absence of clinical disease, mitochondrial homeostasis becomes disrupted (e.g., redox balance, mitochondrial DNA damage, oxidative metabolism, and mitochondrial quality control). Mitochondrial dysregulation leads to the accumulation of damaged and dysfunctional mitochondria, producing excessive reactive oxygen species and perpetuating mitochondrial dysfunction. In addition, mitochondrial DNA, cardiolipin, and N-formyl peptides are potent activators of cell-intrinsic and -extrinsic inflammatory pathways. These age-related mitochondrial changes contribute to the development of cardiovascular diseases. This review covers the impact of aging on mitochondria and links these mechanisms to therapeutic implications for age-associated cardiovascular diseases.

Therapeutic efficacies of mitochondria-targeted esculetin and metformin in the improvement of age-associated atherosclerosis via regulating AMPK activation.

Atherosclerosis, in general, is an age-associated cardiovascular disease wherein a progressive decline in mitochondrial function due to aging majorly contributes to the disease development. Mitochondria-derived ROS due to dysregulated endothelial cell function accentuates the progression of atherosclerotic plaque formation. To circumvent this, mitochondrially targeted antioxidants are emerging as potential candidates to combat metabolic abnormalities. Recently, we synthesized an alkyl TPP+ tagged esculetin (Mito-Esc), and in the current study, we investigated the therapeutic efficacies of Mito-Esc and metformin, a well-known anti-diabetic drug, in the amelioration of age-associated plaque formation in the aortas of 12months aged Apoe-/- and 20months aged C57BL/6 mice, in comparison to young C57BL/6 control mice. Administration of Mito-Esc or metformin significantly reduced age-induced atherosclerotic lesion area, macrophage polarization, vascular inflammation, and senescence. Further, chronic passaging of human aortic endothelial cells (HAEC) with either Mito-Esc or metformin significantly delayed cellular senescence via the activation of the AMPK-SIRT1/SIRT6 axis. Conversely, depletion of either AMPK/SIRT1/SIRT6 caused premature senescence. Consistent with this, Mito-Esc or metformin treatment attenuated NFkB-mediated inflammatory signaling and enhanced ARE-mediated anti-oxidant responses in comparison to late passage control HAECs. Importantly, culturing of HAECs for several passages with either Mito-Esc or metformin significantly improved mitochondrial function. Overall, Mito-Esc and metformin treatments delay age-associated atherosclerosis by regulating vascular senescence via the activation of AMPK-SIRT1/SIRT6 axis.

Abstract 15962: Validation of the Senescence-Associated Secretome to Predict Mortality in Patients With Degenerative Aortic Valve Stenosis

Introduction: The senescence-associated secretory phenotype (SASP) is a potential driver of age-related risk reflecting advanced biological aging. Circulating SASP components include pro-inflammatory cytokines, growth modulators and matrix remodelling proteases. Aortic valve stenosis (AVS) is the prototypical inflammatory age-associated cardiovascular disease. Hypothesis: To identify circulating SASP components with an impact on prognosis in elderly pts with AVS. Methods: In a derivation cohort (n=120), circulating levels of 24 SASP components were measured using Luminex Multiplex ELISA, before undergoing TAVR. ROC curves and Youden-index derived optimal cut-off values were used to assess the predictive power of each SASP for long-term mortality. In a validation cohort (n=198), the significant predictors of mortality identified in the derivation cohort, as well as a panel of 3 independent predictors in multivariate analyses, were prospectively validated. Results: In the derivation cohort, 9 out of 24 SASP components significantly predicted mortality in univariate analyses with AUC>0.62; only 3 (GDF-15, ICAM-1, and osteoprotegerin) remained independent predictors in multivariate analyses (all p<0.03). All 3 were confirmed as significant independent predictors of mortality in the validation cohort (see AUC curves). After adjustment for clinical parameters, a score based on the cumulative number of these 3 SASP components showed a substantial increase in long-term mortality after TAVR for each additional positive marker (see KM-curves). Conclusions: This study validates high levels of 3 SASP components reflecting different pathophysiological pathways of senescence as independent predictors of long-term mortality in AVS. Their cumulative occurrence provides a deeply improved discrimination power and, may serve as a much needed risk stratification tool in elderly patients with AVS undergoing TAVR.

Effects of Regular Exercise on Vascular Function with Aging: Does Sex Matter?

Vascular aging, featuring endothelial dysfunction and large elastic artery stiffening, is a major risk factor for the development of age-associated cardiovascular diseases (CVD). Vascular aging is largely mediated by an excessive production of reactive oxygen species (ROS) and increased inflammation leading to reduced bioavailability of the vasodilatory molecule nitric oxide and remodeling of the arterial wall. Other cellular mechanisms (i.e., mitochondrial dysfunction, impaired stress response, deregulated nutrient sensing, cellular senescence), termed "hallmarks" or "pillars" of aging, may also contribute to vascular aging. Gonadal aging, which largely impacts women but also impacts some men, modulates the vascular aging process. Regular physical activity, including both aerobic and resistance exercise, is a first-line strategy for reducing CVD risk with aging. Although exercise is an effective intervention to counter vascular aging, there is considerable variation in the vascular response to exercise training with aging. Aerobic exercise improves large elastic artery stiffening in both middle-age/older men and women and enhances endothelial function in middle-age/older men by reducing oxidative stress and inflammation and preserving NO bioavailability; however, similar aerobic exercise training improvements are not consistently observed in estrogen-deficient postmenopausal women. Sex differences in adaptations to exercise may be related to gonadal aging and declines in estrogen in women that influence cellular-molecular mechanisms, disconnecting favorable signaling in the vasculature induced by exercise training. The present review will summarize the current state of knowledge on vascular adaptations to regular aerobic and resistance exercise with aging, the underlying mechanisms involved, and the moderating role of biological sex.

Senolytics prevent caveolar CaV 3.2-RyR axis malfunction in old vascular smooth muscle.

Aging is a major risk factor for cardiovascular diseases. Our previous studies demonstrate that aging impairs the caveolar T-type CaV 3.2-RyR axis for extracellular Ca2+ influx to trigger Ca2+ sparks in vascular smooth muscle cells (VSMCs). We hypothesize that the administration of senolytics, which can selectively clear senescent cells, could preserve the caveolar CaV 3.2-RyR axis in aging VSMCs. In this study, 10-month-old mice were administered the senolytics cocktail consisting of dasatinib (5 mg/kg) and quercetin (50 mg/kg) or vehicle bi-weekly for 4 months. Using VSMCs from mouse mesenteric arteries, we found that Ca2+ sparks were diminished after caveolae disruption by methyl-β-cyclodextrin (10 mM) in cells from D + Q treated but not vehicle-treated 14-month-old mice. D + Q treatment promoted the expression of CaV 3.2 in 14-month-old mesenteric arteries. Structural analysis using electron tomography and immunofluorescence staining revealed the remodeling of caveolae and co-localization of CaV 3.2-Cav-1 in D + Q treatment aged mesenteric arteries. In keeping with theoretical observations, Cav 3.2 channel inhibition by Ni2+ (50 μM) suppressed Ca2+ in VSMCs from the D + Q group, with no effect observed in vehicle-treated arteries. Our study provides evidence that age-related caveolar CaV 3.2-RyR axis malfunction can be alleviated by pharmaceutical intervention targeting cellular senescence. Our findings support the potential of senolytics for ameliorating age-associated cardiovascular disease.

Cardiac iron metabolism during aging – Role of inflammation and proteolysis

Iron is the most abundant trace element in the human body. Since iron can switch between its 2-valent and 3-valent form it is essential in various physiological processes such as energy production, proliferation or DNA synthesis. Especially high metabolic organs such as the heart rely on iron-associated iron-sulfur and heme proteins. However, due to switches in iron oxidation state, iron overload exhibits high toxicity through formation of reactive oxygen species, underlining the importance of balanced iron levels. Growing evidence demonstrates disturbance of this balance during aging. While age-associated cardiovascular diseases are often related to iron deficiency, in physiological aging cardiac iron accumulates. To understand these changes, we focused on inflammation and proteolysis, two hallmarks of aging, and their role in iron metabolism. Via the IL-6-hepcidin axis, inflammation and iron status are strongly connected often resulting in anemia accompanied by infiltration of macrophages. This tight connection between anemia and inflammation highlights the importance of the macrophage iron metabolism during inflammation. Age-related decrease in proteolytic activity additionally affects iron balance due to impaired degradation of iron metabolism proteins. Therefore, this review accentuates alterations in iron metabolism during aging with regards to inflammation and proteolysis to draw attention to their implications and associations.

Cardiovascular aging: the mitochondrial influence.

Age-associated cardiovascular disease is becoming progressively prevalent due to the increased lifespan of the population. However, the fundamental mechanisms underlying the aging process and the corresponding decline in tissue functions are still poorly understood. The heart has a very high energy demand and the cellular energy needed to sustain contraction is primarily generated by mitochondrial oxidative phosphorylation. Mitochondria are also involved in supporting various metabolic processes, as well as activation of the innate immune response and cell death pathways. Given the central role of mitochondria in energy metabolism and cell survival, the heart is highly susceptible to the effects of mitochondrial dysfunction. These key organelles have been implicated as underlying drivers of cardiac aging. Here, we review the evidence demonstrating the mitochondrial contribution to the cardiac aging process and disease susceptibility. We also discuss the potential mechanisms responsible for the age-related decline in mitochondrial function.

Autophagy in homocysteine‑induced HUVEC senescence.

The senescence of vascular endothelial cells (VECs) drives the occurrence and development of cardiovascular disease (CVD). Homocysteine (HCY) is a general risk factor for age-associated CVDs. Autophagy, an evolutionarily conserved lysosomal protein degradation pathway, serves a part in VEC senescence. The purpose of this study was to investigate the role of autophagy in HCY-induced endothelial cell senescence and explore novel mechanisms and therapeutic approaches for related CVDs. Human umbilical vein endothelial cells (HUVECs) were isolated from fresh umbilical cords of healthy pregnancies. Cell Counting Kit-8, flow cytometry and senescence-associated (SA) β-galactosidase (Gal) staining demonstrated that HCY induced HUVEC senescence by decreasing cell proliferation, arresting cell cycle and increasing the number of SA-β-Gal-positive cells. Stub-RFP-Sens-GFP-LC3 autophagy-related double fluorescence lentivirus revealed that HCY increased autophagic flux. Further, inhibition of autophagy using 3-methyladenine increased HCY-induced HUVEC senescence. By contrast, the induction of autophagy via rapamycin alleviated HCY-induced HUVEC senescence. Finally, the detection of reactive oxygen species (ROS) with ROS kit showed that HCY increased intracellular ROS, whereas induction of autophagy reduced intracellular ROS. In conclusion, HCY increased HUVEC senescence and upregulated autophagy; moderate autophagy could reverse HCY-induced cell senescence. Autophagy may alleviate HCY-induced cell senescence by decreasing intracellular ROS. This provides insight into the underlying mechanism of HCY-induced VEC senescence and potential treatments for age-associated CVDs.

Role of noncoding RNAs in cardiac ageing.

The global population is estimated to reach 9.8 billion by 2050, of which 2.1 billion will comprise individuals above 60 years of age. As the number of elderly is estimated to double from 2017, it is a victory of the modern healthcare system but also worrisome as ageing, and the onset of chronic disease are correlated. Among other chronic conditions, cardiovascular diseases (CVDs) are the leading cause of death in the aged population. While the underlying cause of the age-associated development of CVDs is not fully understood, studies indicate the role of non-coding RNAs such as microRNAs (miRNAs) and long noncoding RNAs (lnc-RNAs) in the development of age-associated CVDs. miRNAs and lnc-RNAs are non-coding RNAs which control gene expression at the post-transcriptional level. The expression of specific miRNAs and lnc-RNAs are reportedly dysregulated with age, leading to cardiovascular system changes and ultimately causing CVDs. Since miRNAs and lnc-RNAs play several vital roles in maintaining the normal functioning of the cardiovascular system, they are also being explored for their therapeutic potential as a treatment for CVDs. This review will first explore the pathophysiological changes associated with ageing. Next, we will review the known mechanisms underlying the development of CVD in ageing with a specific focus on miRNA and lnc-RNAs. Finally, we will discuss the therapeutic options and future challenges towards healthy cardiac ageing. With the global ageing population on the rise, this review will provide a fundamental understanding of some of the underlying molecular mechanisms of cardiac ageing.

Molecular explanation of Wnt/βcatenin antagonist pyrvinium mediated calcium equilibrium changes in aging cardiovascular disorders.

The symptoms of ageing are somewhat different and can lead to the altered role of the cardiovascular system at the levels of genetic, biochemical, tissue, organ, and systems. Ageing is an autonomous cardiovascular risk factor. In the ageing rat heart, oxidative and inflammatory stress, immune cell infiltration, increasing myeloperoxidase function, elevated caspase-3 activity, and protein fibronectins were detected and associated with ageing and cardiovascular disease. The intracellular Ca2 + homeostasis disturbed in an older heart dramatically increases cardiomyopathy, atherosclerosis, stroke, ischemia, myocardial infarction, hypertrophy, remodelling, and hypertension. Evidence shows that suppression of Wnt/β signals prevents cardiovascular dysfunction, such as remodelling, high blood pressure, and excessive overload stress. However, one study has shown that the pharmacological disruption of Wnt-β-catenin by decreasing expression of α-smooth muscle actin, fibronectin and collagen I proteins attenuates angiotensin II mediated hypertension cardiac fibrosis. Thus, this review examined the impacts of calcium overload and age-related diseases, including cardiovascular. Energy dysregulation, calcium overloading, and mitochondrial dysfunction are the main activities causing cardiovascular disease linked with age. Therefore, the current study explores that age-associated cardiovascular disease has triggered the WNT/β-catenin pathway, and pharmacological inhibition can delay pathological changes by attenuating calcium dyshomeostasis.

Modern Concepts in Cardiovascular Disease: Inflamm-Aging.

The improvements in healthcare services and quality of life result in a longer life expectancy and a higher number of aged individuals, who are inevitably affected by age-associated cardiovascular (CV) diseases. This challenging demographic shift calls for a greater effort to unravel the molecular mechanisms underlying age-related CV diseases to identify new therapeutic targets to cope with the ongoing aging "pandemic". Essential for protection against external pathogens and intrinsic degenerative processes, the inflammatory response becomes dysregulated with aging, leading to a persistent state of low-grade inflammation known as inflamm-aging. Of interest, inflammation has been recently recognized as a key factor in the pathogenesis of CV diseases, suggesting inflamm-aging as a possible driver of age-related CV afflictions and a plausible therapeutic target in this context. This review discusses the molecular pathways underlying inflamm-aging and their involvement in CV disease. Moreover, the potential of several anti-inflammatory approaches in this context is also reviewed.

Chronic activation of cardiac Atg-5 and pancreatic Atg-7 by intermittent fasting alleviates acute myocardial infarction in old rats

BackgroundAging is associated with cardiovascular and metabolic changes, increasing the susceptibility to acute myocardial infarction (AMI). Intermittent fasting (IF) has a beneficial effect on the age-associated cardiovascular diseases. The present study was planned to investigate the possible protective effect of IF against acute AMI induced by isoproterenol (ISO) in old rats and its possible underlying mechanisms mediated by heart and pancreatic autophagy. Thirty Male Wistar rats were divided into four groups: adult; old; Old-ISO (rats subjected to AMI by ISO) and Old-F-ISO groups (rats were subjected to IF for 4 weeks and AMI by ISO).ResultsIF significantly increased the mRNA expression of cardiac Atg-5 and pancreatic Atg-7 in Old-F-ISO versus old and adult groups. This was associated with a significant decrease in serum troponin-I, serum creatine kinase (CK-MB), cardiac malondialdehyde and cardiac TNF-α, fasting plasma glucose, and HOMA-IR in Old-F-ISO compared to Old-ISO group. Also, IF significantly decreased the age-related overall and visceral obesity in Old-F-ISO versus old and Old-ISO groups. Histological studies revealed attenuation of the local inflammatory response in Old-F-ISO versus Old-ISO group. Pancreatic Atg-7 and heart Atg-5 were significantly increased in Old-ISO versus old rats.ConclusionsIF protects against acute AMI in old rats, possibly, via chronic activation of heart Atg-5 and pancreatic Atg-7, and alleviation of age-related overall and visceral obesity. Thus, IF could be a dietary lifestyle modification for attenuation of the susceptibility to acute AMI in aged population. On the other hand, acute activation of heart and pancreatic autophagy by ISO might augment cardiac injury.

Sirtuin 3 (SIRT3) Pathways in Age-Related Cardiovascular and Neurodegenerative Diseases.

Age-associated cardiovascular and neurodegenerative diseases lead to high morbidity and mortality around the world. Sirtuins are vital enzymes for metabolic adaptation and provide protective effects against a wide spectrum of pathologies. Among sirtuins, mitochondrial sirtuin 3 (SIRT3) is an essential player in preserving the habitual metabolic profile. SIRT3 activity declines as a result of aging-induced changes in cellular metabolism, leading to increased susceptibility to endothelial dysfunction, hypertension, heart failure and neurodegenerative diseases. Stimulating SIRT3 activity via lifestyle, pharmacological or genetic interventions could protect against a plethora of pathologies and could improve health and lifespan. Thus, understanding how SIRT3 operates and how its protective effects could be amplified, will aid in treating age-associated diseases and ultimately, in enhancing the quality of life in elders.

Sirtuin 6 Protects Against Oxidative Stress and Vascular Dysfunction in Mice.

Objective: Sirtuin deacetylases are major regulators of organismal aging, and while depletion of sirtuin 6 (SIRT6) in mice results in a profound progeroid phenotype, the role of SIRT6 in the regulation of vasomotor function is unknown. Thus, our objective was to test the hypothesis that reductions in SIRT6 elicit endothelial dysfunction in young, genetically altered mice.Results and Approach: We used young (3 month old), littermate-matched, SIRT6 wild-type (WT), and SIRT6 heterozygous (HET) mice. SIRT6 expression (qRT-PCR) was reduced by 50% in HET mice. Carotid vessel responses to acetylcholine, sodium nitroprusside, U46619, and serotonin were examined in isolated organ chamber baths. Relaxation in response to acetylcholine (ACH) was impaired in HET mice compared to littermate-matched WT controls (67 ± 3% versus 76 ± 3%, respectively; p < 0.05), while responses to sodium nitroprusside were unchanged. Short-term incubation of carotid rings with the NAD(P)H oxidase inhibitor, apocynin, significantly improved in vessels from HET mice but not their WT littermates. Peak tension generated in response to either U46619 or serotonin was significantly blunted in HET mice compared to their WT littermates.Conclusion: These data suggest that SIRT6 is a key regulator of vasomotor function in conduit vessels. More specifically, we propose that SIRT6 serves as a tonic suppressor of NAD(P)H oxidase expression and activation, as inhibition of NAD(P)H oxidase improved endothelial function in SIRT6 haploinsufficient mice. Collectively, SIRT6 activation and/or histone acetyltransferase inhibition may be useful therapeutic approaches to reduce endothelial dysfunction and combat age-associated cardiovascular disease.

Oxidative Stress and Inflammation Are Associated With Age-Related Endothelial Dysfunction in Men With Low Testosterone.

Vascular aging, including endothelial dysfunction secondary to oxidative stress and inflammation, increases the risk for age-associated cardiovascular disease (CVD). Low testosterone in middle-aged/older men is associated with increased CVD risk. We hypothesized that low testosterone contributes to age-associated endothelial dysfunction, related in part to greater oxidative stress and inflammation. This cross-sectional study included 58 healthy, nonsmoking men categorized as young (N = 20; age 29 ± 4 years; testosterone 500 ± 58 ng/dL), middle-aged/older with higher testosterone (N = 20; age 60 ± 6 years; testosterone 512 ± 115 ng/dL), and middle-aged/older lower testosterone (N = 18; age 59 ± 8 years; testosterone 269 ± 48 ng/dL). Brachial artery flow-mediated dilation (FMDBA) was measured during acute infusion of saline (control) and vitamin C (antioxidant). Markers of oxidative stress (total antioxidant status and oxidized low-density lipoprotein cholesterol), inflammation (interleukin [IL]-6 and C-reactive protein [CRP]), and androgen deficiency symptoms were also examined. During saline, FMDBA was reduced in middle-aged/older compared with young, regardless of testosterone status (P < 0.001). FMDBA was reduced in middle-aged/older lower testosterone (3.7% ± 2.0%) compared with middle-aged/older higher testosterone (5.7% ± 2.2%; P = 0.021), independent of symptoms. Vitamin C increased FMDBA (to 5.3% ± 1.6%; P = 0.022) in middle-aged/older lower testosterone but had no effect in young (P = 0.992) or middle-aged/older higher testosterone (P = 0.250). FMDBA correlated with serum testosterone (r = 0.45; P < 0.001), IL-6 (r = -0.41; P = 0.002), and CRP (r = -0.28; P = 0.041). Healthy middle-aged/older men with low testosterone appear to have greater age-associated endothelial dysfunction, related in part to greater oxidative stress and inflammation. These data suggest that low testosterone concentrations may contribute to accelerated vascular aging in men.

Dietary Nucleotides Retard Oxidative Stress-Induced Senescence of Human Umbilical Vein Endothelial Cells.

Several lines of evidence suggest an inhibitory role of dietary nucleotides (NTs) against oxidative stress and inflammation, which promote senescence in age-associated cardiovascular diseases. We sought to test whether the dietary NTs could retard the hydrogen peroxide (H2O2)-induced senescence of human umbilical vein endothelial cells (HUVECs) and to elucidate the efficiency of different NTs as well as the potential mechanism. Senescence was induced in HUVECs by 4 h exposure to 200 µM H2O2 and was confirmed using senescence-associated-β-galactosidase staining (SA-β-gal), cell viability, and Western blot analyses of p16INK4A and p21Waf1/Cip1 after 24 h administration of growth medium. We find that NTs retards oxidative stress-induced HUVECs senescence, as shown by a lower percentage of SA-β-gal-positive cells, lower expression of p16INK4A, and p21Waf1/Cip1 as well as higher cell viability. GMP100 was the most excellent in delaying HUVECs senescence, which was followed by the NTs mixture, NMN, CMP50, and UMP50/100, while AMP retards HUVECs senescence by specifically reducing p15INK4b expression. NTs all have significant anti-inflammatory effects; AMP and CMP were more prominent in restoring mitochondrial function, GMP and CMP were more competent at eliminating ROS and MDA, while AMP and UMP were more efficient at enhancing antioxidant enzyme activity. The role of the NTs mixture in retarding HUVECs senescence is full-scaled. These results stated that the mechanisms of NTs retarding HUVECs senescence could be related to its antioxidant and anti-inflammation properties promoting cell proliferation and protecting mitochondrial function activities.

Androgen-Regulated Cardiac Metabolism in Aging Men.

The prevalence of cardiovascular mortality is higher in men than in age-matched premenopausal women. Gender differences are linked to circulating sex-related steroid hormone levels and their cardio-specific actions, which are critical factors involved in the prevalence and features of age-associated cardiovascular disease. In women, estrogens have been described as cardioprotective agents, while in men, testosterone is the main sex steroid hormone. The effects of testosterone as a metabolic regulator and cardioprotective agent in aging men are poorly understood. With advancing age, testosterone levels gradually decrease in men, an effect associated with increasing fat mass, decrease in lean body mass, dyslipidemia, insulin resistance and adjustment in energy substrate metabolism. Aging is associated with a decline in metabolism, characterized by modifications in cardiac function, excitation-contraction coupling, and lower efficacy to generate energy. Testosterone deficiency -as found in elderly men- rapidly becomes an epidemic condition, associated with prominent cardiometabolic disorders. Therefore, it is highly probable that senior men showing low testosterone levels will display symptoms of androgen deficiency, presenting an unfavorable metabolic profile and increased cardiovascular risk. Moreover, recent reports establish that testosterone replacement improves cardiomyocyte bioenergetics, increases glucose metabolism and reduces insulin resistance in elderly men. Thus, testosterone-related metabolic signaling and gene expression may constitute relevant therapeutic target for preventing, or treating, age- and gender-related cardiometabolic diseases in men. Here, we will discuss the impact of current evidence showing how cardiac metabolism is regulated by androgen levels in aging men.

Inspiratory Muscle Strength Training Improves Vascular Endothelial Function in Older Adults by Altering Circulating Factors that Suppress Superoxide and Enhance Nitric Oxide

BackgroundVascular endothelial dysfunction associated with decreased nitric oxide (NO)‐bioavailability secondary to excessive superoxide‐associated oxidative stress is a key antecedent of age‐associated cardiovascular diseases. High‐resistance inspiratory muscle strength training (IMST) is a promising form of time‐efficient physical training for promoting cardiovascular health with aging. However, the efficacy and mechanisms of IMST for improving endothelial function in older adults have not been established. We hypothesized IMST may induce changes in the molecular composition of the circulating blood that improve endothelial function via superoxide suppression‐related increases in NO bioavailability.PurposeTo determine the efficacy of IMST for improving vascular endothelial function in vivo, the influence of IMST‐induced changes in circulating factors on endothelial superoxide and NO production ex vivo, and IMST‐induced changes in the molecular composition of the circulation.MethodsTwenty older adults underwent 6 weeks of IMST (30 breaths/day; 6 days/week; 75% maximum inspiratory pressure [PIMAX]) (n=10, 5M/5F, age: 68±2 years) or low‐resistance sham (15% PIMAX) training (n=10, 6M/4F, age 70±2 years) in a randomized, double‐blind study. Vascular endothelial function was assessed via brachial artery flow‐mediated dilation [FMDBA]. HUVECs were cultured with serum collected at baseline and post‐intervention (n=12; 5 IMST, 7 sham). NO production stimulated with acetylcholine and basal superoxide production from HUVECs were measured using fluorescent microscopy. Plasma metabolite levels were assessed via targeted metabolomics (n=14; 7 IMST, 7 sham) at baseline and post‐intervention with ultra‐high‐performance liquid chromatography‐mass spectrometry.ResultsFMDBA increased 45% after 6 weeks of IMST (pre: 4.7±0.8 Δ%, post: 6.8±0.7 Δ%; p=0.01) but not after sham training (pre: 3.7±0.6 Δ%, post: 3.8±0.6 Δ%; p=0.99), such that FMDBA was 79% higher in the IMST group compared to sham training post‐intervention (p=0.01). HUVEC production of NO was 66% higher (p=0.04) while superoxide production was 38% lower post‐intervention in the IMST group vs. sham, though the latter was not statistically significant (p=0.17). Plasma metabolomics revealed greater levels of arginine (p=0.02) and ornithine (p=0.06) in the IMST group vs. sham post‐intervention, consistent with increased NO production. A greater level of dehydroascorbate (p=0.04) and changes in markers of glutathione synthesis (decreased alanine p=0.02; increased cystine p=0.06) were observed in the IMST group vs. sham post‐intervention, suggesting greater antioxidant defense status with IMST.ConclusionThese findings suggest IMST is a promising intervention for improving vascular endothelial function in older adults, in part by inducing changes in the molecular composition of the blood that increases NO bioavailability by suppressing superoxide.Support or Funding InformationAHA 18POST33990034, R21 AG061677

Vascular Smooth Muscle Cell-Specific Progerin Expression Provokes Contractile Impairment in a Mouse Model of Hutchinson-Gilford Progeria Syndrome that Is Ameliorated by Nitrite Treatment.

Cardiovascular disease (CVD) is the main cause of death worldwide, and aging is its leading risk factor. Aging is much accelerated in Hutchinson–Gilford progeria syndrome (HGPS), an ultra-rare genetic disorder provoked by the ubiquitous expression of a mutant protein called progerin. HGPS patients die in their teens, primarily due to cardiovascular complications. The primary causes of age-associated CVD are endothelial dysfunction and dysregulated vascular tone; however, their contribution to progerin-induced CVD remains poorly characterized. In the present study, we found that progeroid LmnaG609G/G609G mice with ubiquitous progerin expression show both endothelial dysfunction and severe contractile impairment. To assess the relative contribution of specific vascular cell types to these anomalies, we examined LmnaLCS/LCSTie2Cretg/+ and LmnaLCS/LCSSm22αCretg/+ mice, which express progerin specifically in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), respectively. Whereas vessel contraction was impaired in mice with VSMC-specific progerin expression, we observed no endothelial dysfunction in mice with progerin expression restricted to VSMCs or ECs. Vascular tone regulation in progeroid mice was ameliorated by dietary sodium nitrite supplementation. Our results identify VSMCs as the main cell type causing contractile impairment in a mouse model of HGPS that is ameliorated by nitrite treatment.

The Role of Signaling Pathways of Inflammation and Oxidative Stress in Development of Senescence and Aging Phenotypes in Cardiovascular Disease.

The ASK1-signalosome→p38 MAPK and SAPK/JNK signaling networks promote senescence (in vitro) and aging (in vivo, animal models and human cohorts) in response to oxidative stress and inflammation. These networks contribute to the promotion of age-associated cardiovascular diseases of oxidative stress and inflammation. Furthermore, their inhibition delays the onset of these cardiovascular diseases as well as senescence and aging. In this review we focus on whether the (a) ASK1-signalosome, a major center of distribution of reactive oxygen species (ROS)-mediated stress signals, plays a role in the promotion of cardiovascular diseases of oxidative stress and inflammation; (b) The ASK1-signalosome links ROS signals generated by dysfunctional mitochondrial electron transport chain complexes to the p38 MAPK stress response pathway; (c) the pathway contributes to the sensitivity and vulnerability of aged tissues to diseases of oxidative stress; and (d) the importance of inhibitors of these pathways to the development of cardioprotection and pharmaceutical interventions. We propose that the ASK1-signalosome regulates the progression of cardiovascular diseases. The resultant attenuation of the physiological characteristics of cardiomyopathies and aging by inhibition of the ASK1-signalosome network lends support to this conclusion. Importantly the ROS-mediated activation of the ASK1-signalosome p38 MAPK pathway suggests it is a major center of dissemination of the ROS signals that promote senescence, aging and cardiovascular diseases. Pharmacological intervention is, therefore, feasible through the continued identification of potent, non-toxic small molecule inhibitors of either ASK1 or p38 MAPK activity. This is a fruitful future approach to the attenuation of physiological aspects of mammalian cardiomyopathies and aging.