Anti-aging medicine: molecular basis for endothelial cell-targeted strategies - a mini-review

Cellular Components of the Blood-Brain Barrier and Their Involvement in Aging-Associated Cognitive Impairment

Human life expectancy has been significantly extended, which poses major challenges to our healthcare and social systems. Aging-associated cognitive impairment is attributed to endothelial dysfunction in the cardiovascular system and neurological dysfunction in the central nervous system. The central nervous system is considered an immune-privileged tissue due to the exquisite protection provided by the blood-brain barrier. The present review provides an overview of the structure and function of blood-brain barrier, extending the cell components of blood-brain barrier from endothelial cells and pericytes to astrocytes, perivascular macrophages and oligodendrocyte progenitor cells. In particular, the pathological changes in the blood-brain barrier in aging, with special focus on the underlying mechanisms and molecular changes, are presented. Furthermore, the potential preventive/therapeutic strategies against aging-associated blood-brain barrier disruption are discussed.

JCAD promotes arterial thrombosis through PI3K/Akt modulation: a translational study

AIMS

Variants of the junctional cadherin 5 associated (JCAD) locus associate with acute coronary syndromes. JCAD promotes experimental atherosclerosis through the large tumor suppressor kinase 2 (LATS2)/Hippo pathway. This study investigates the role of JCAD in arterial thrombosis.

METHODS AND RESULTS

JCAD knockout (Jcad-/-) mice underwent photochemically induced endothelial injury to trigger arterial thrombosis. Primary human aortic endothelial cells (HAECs) treated with JCAD small interfering RNA (siJCAD), LATS2 small interfering RNA (siLATS2) or control siRNA (siSCR) were employed for in vitro assays. Plasma JCAD was measured in patients with chronic coronary syndrome or ST-elevation myocardial infarction (STEMI). Jcad-/- mice displayed reduced thrombogenicity as reflected by delayed time to carotid occlusion. Mechanisms include reduced activation of the coagulation cascade [reduced tissue factor (TF) expression and activity] and increased fibrinolysis [higher thrombus embolization episodes and D-dimer levels, reduced vascular plasminogen activator inhibitor (PAI)-1 expression]. In vitro, JCAD silencing inhibited TF and PAI-1 expression in HAECs. JCAD-silenced HAECs (siJCAD) displayed increased levels of LATS2 kinase. Yet, double JCAD and LATS2 silencing did not restore the control phenotype. si-JCAD HAECs showed increased levels of phosphoinositide 3-kinases (PI3K)/ proteinkinase B (Akt) activation, known to downregulate procoagulant expression. The PI3K/Akt pathway inhibitor-wortmannin-prevented the effect of JCAD silencing on TF and PAI-1, indicating a causative role. Also, co-immunoprecipitation unveiled a direct interaction between JCAD and Akt. Confirming in vitro findings, PI3K/Akt and P-yes-associated protein levels were higher in Jcad-/- animals. Lastly, as compared with chronic coronary syndrome, STEMI patients showed higher plasma JCAD, which notably correlated positively with both TF and PAI-1 levels.

CONCLUSIONS

JCAD promotes arterial thrombosis by modulating coagulation and fibrinolysis. Herein, reported translational data suggest JCAD as a potential therapeutic target for atherothrombosis.

The glycolytic process in endothelial cells and its implications

Endothelial cells play an obligatory role in regulating local vascular tone and maintaining homeostasis in vascular biology. Cell metabolism, converting food to energy in organisms, is the primary self-sustaining mechanism for cell proliferation and reproduction, structure maintenance, and fight-or-flight responses to stimuli. Four major metabolic processes take place in the energy-producing process, including glycolysis, oxidative phosphorylation, glutamine metabolism, and fatty acid oxidation. Among them, glycolysis is the primary energy-producing mechanism in endothelial cells. The present review focused on glycolysis in endothelial cells under both physiological and pathological conditions. Since the switches among metabolic processes precede the functional changes and disease developments, some prophylactic and/or therapeutic strategies concerning the role of glycolysis in cardiovascular disease are discussed.

Sex differences in cardiovascular risk factors for myocardial infarction

BACKGROUND

Cardiovascular disease is a leading cause of mortality worldwide. This study investigated the effects of sex on traditional cardiovascular risk factors for remote myocardial infarction in a community.

METHODS

A cross-sectional study was performed comprising 20,899 participants who underwent physical examination from 2013 to 2015, including systemic blood pressure and 12-lead electrocardiogram monitoring. Fasting blood samples were collected for blood cell counts and biochemistry tests. Remote myocardial infarction was diagnosed on the basis of electrocardiogram findings.

RESULTS

A total of 71 male and 21 female patients aged over 50 years were identified with remote myocardial infarction. In the female cohort, low-density lipoprotein (LDL), total cholesterol (TC), as well as high-density lipoprotein (HDL) were negatively correlated with myocardial infarction after adjusting for age. In the male cohort, after adjusting for age, serum levels of glycated hemoglobin (HbA1c) and fasting glucose were positively correlated with myocardial infarction, but the lipid profile, including low-density lipoprotein (LDL), total cholesterol (TC), and high-density lipoprotein (HDL), was negatively correlated with remote myocardial infarction.

CONCLUSION

In the male population, dyslipidemia and abnormal glucose metabolism play a role in myocardial infarction. In the female population, dyslipidemia is independent of glucose metabolism. This study highlights sex differences in the regulation of lipids and glucose metabolism in patients with remote myocardial infarction.

Anti-aging and Sunscreens: Paradigm Shift in Cosmetics

Skin, being one of the vital organs and a protective barrier needs to be pampered and taken care of from early childhood. It is the most visible and the widest exposed organ and by far reflects the general health condition and the aging process in humans. Both intrinsic and extrinsic factors contribute to this complex biological process of skin aging. In recent times, skin health and its beauty is perceived as an indicator of one’s health which has resulted in an increasing demand for anti-aging products. Exposure to UV radiation is considered to be one of the factors responsible for aging termed as photoaging. In this review, we have discussed the various factors which may accelerate the process of skin aging. Various approaches and strategies to delay the process of skin aging have been emphasized upon. The patents filed in the area of anti-aging and sunscreen products have also been reviewed to gain an insight into the new formulations which have been developed as an anti-aging product. There has been a tremendous rise in the cosmetic and cosmeceuticals market with products having a dual activity of anti-aging and sun protection. Research is constantly on the rise to ensure the safety of these products. Alternatives to the current topical application of sunscreen are being considered to overcome the drawback of reapplication of the sunscreen often which can be a boon to the cosmeceutical market.

Endothelial SIRT1 prevents adverse arterial remodeling by facilitating HERC2-mediated degradation of acetylated LKB1

Aims-SIRT1 exerts potent activity against cellular senescence and vascular ageing. By decreasing LKB1 protein levels, it promotes the survival and regeneration of endothelial cells. The present study aims to investigate the molecular mechanisms underlying SIRT1-mediated LKB1 degradation for the prevention of vascular ageing.

Methods and Results-Co-immunoprecipitation assay demonstrated that SIRT1, via its amino-terminus, binds to the DOC domain of HERC2 [HECT and RLD domain containing E3 ubiquitin protein ligase 2], which then ubiquitinates LKB1 in the nuclear compartment of endothelial cells. Site-directed mutagenesis revealed that acetylation at lysine (K) 64 of LKB1 triggers the formation of SIRT1/HERC2/LKB1 protein complex and subsequent proteasomal degradation. In vitro cellular studies suggested that accumulation of acetylated LKB1 in the nucleus leads to endothelial activation, in turn stimulating the proliferation of vascular smooth muscle cells and the production of extracellular matrix proteins. Chromatin immunoprecipitation quantitative PCR confirmed that acetylated LKB1 interacts with and activates TGFβ1 promoter, which is inhibited by SIRT1. Knocking down either SIRT1 or HERC2 results in an increased association of LKB1 with the positive regulatory elements of TGFβ1 promoter. In mice without endothelial nitric oxide synthase, selective overexpression of human SIRT1 in endothelium prevents hypertension and age-related adverse arterial remodeling. Lentiviral-mediated knockdown of HERC2 abolishes the beneficial effects of endothelial SIRT1 on both arterial remodeling and arterial blood pressure control.

Conclusion-By downregulating acetylated LKB1 protein via HERC2, SIRT1 fine-tunes the crosstalk between endothelial and vascular smooth muscle cells to prevent adverse arterial remodeling and maintain vascular homeostasis.

Ginseng: An Nonnegligible Natural Remedy for Healthy Aging

Aging is an irreversible physiological process that affects all humans. Numerous theories have been proposed to regarding the process from a Western medicine perspective; however, ancient Chinese medicine practices and theories have increasingly gained attention, particularly ginseng, a grass that has been studied for the anti-aging properties of its active constituents. This review seeks to analyze current data on ginseng and its anti-aging properties. The plant species, characteristics, and active ingredients will be introduced. The main part of this review is focused on ginseng and its active components with regards to their effects on prolonging lifespan, the regulation of multiple organ systems including cardiovascular, nervous, immune, and skin, as well as the anti-oxidant and anti-inflammatory properties. The molecular mechanisms of these properties elucidated via various studies are summarized as further evidence of the anti-aging effects of ginseng.

POTENTIAL EFFECTS OF WHOLE-BODY VIBRATION EXERCISES ON BLOOD FLOW KINETICS OF DIFFERENT POPULATIONS: A SYSTEMATIC REVIEW WITH A SUITABLE APPROACH

BACKGROUND

The ability to control skin blood flow decreases with advancing age and some clinical disorders, as in diabetes and in rheumatologic diseases. Feasible clinical strategies such as whole-body vibration exercise (WBVE) are being used without a clear understanding of its effects. The aim of the present study is to review the effects of the WBVE on blood flow kinetics and its feasibility in different populations.

MATERIAL AND METHODS

The level of evidence (LE) of selected papers in PubMed and/or PEDRo databases was determined. We selected randomized, controlled trials in English to be evaluated.

RESULTS

Six studies had LE II, one had LE III-2 and one III-3 according to the NHMRC. A great variability among the protocols was observed but also in the assessment devices; therefore, more research about this topic is warranted.

CONCLUSION

Despite the limitations, it is can be concluded that the use of WBVE has proven to be a safe and useful strategy to improve blood flow. However, more studies with greater methodological quality are needed to clearly define the more suitable protocols.

Propolis Counteracts Some Threats to Honey Bee Health

Honey bees (Apis mellifera) are constantly dealing with threats from pathogens, pests, pesticides and poor nutrition. It is critically important to understand how honey bees' natural immune responses (individual immunity) and collective behavioral defenses (social immunity) can improve bee health and productivity. One form of social immunity in honey bee colonies is the collection of antimicrobial plant resins and their use in the nest architecture as propolis. We review research on the constitutive benefits of propolis on the honey bee immune system, and its known therapeutic, colony-level effects against the pathogens Paenibacillus larvae and Ascosphaera apis. We also review the limited research on the effects of propolis against other pathogens, parasites and pests (Nosema, viruses, Varroa destructor, and hive beetles) and how propolis may enhance bee products such as royal jelly and honey. Although propolis may be a source of pesticide contamination, it also has the potential to be a detoxifying agent or primer of detoxification pathways, as well as increasing bee longevity via antioxidant-related pathways. Throughout this paper, we discuss opportunities for future research goals and present ways in which the beekeeping community can promote propolis use in standard colonies, as one way to improve and maintain colony health and resiliency.

Post-ischaemic silencing of p66Shc reduces ischaemia/reperfusion brain injury and its expression correlates to clinical outcome in stroke

AIM

Constitutive genetic deletion of the adaptor protein p66(Shc) was shown to protect from ischaemia/reperfusion injury. Here, we aimed at understanding the molecular mechanisms underlying this effect in stroke and studied p66(Shc) gene regulation in human ischaemic stroke.

METHODS AND RESULTS

Ischaemia/reperfusion brain injury was induced by performing a transient middle cerebral artery occlusion surgery on wild-type mice. After the ischaemic episode and upon reperfusion, small interfering RNA targeting p66(Shc) was injected intravenously. We observed that post-ischaemic p66(Shc) knockdown preserved blood-brain barrier integrity that resulted in improved stroke outcome, as identified by smaller lesion volumes, decreased neurological deficits, and increased survival. Experiments on primary human brain microvascular endothelial cells demonstrated that silencing of the adaptor protein p66(Shc) preserves claudin-5 protein levels during hypoxia/reoxygenation by reducing nicotinamide adenine dinucleotide phosphate oxidase activity and reactive oxygen species production. Further, we found that in peripheral blood monocytes of acute ischaemic stroke patients p66(Shc) gene expression is transiently increased and that this increase correlates with short-term neurological outcome.

CONCLUSION

Post-ischaemic silencing of p66(Shc) upon reperfusion improves stroke outcome in mice while the expression of p66(Shc) gene correlates with short-term outcome in patients with ischaemic stroke.

Dual role of endothelial nitric oxide synthase in oxidized LDL-induced, p66Shc-mediated oxidative stress in cultured human endothelial cells

BACKGROUND

The aging gene p66Shc, is an important mediator of oxidative stress-induced vascular dysfunction and disease. In cultured human aortic endothelial cells (HAEC), p66Shc deletion increases endothelial nitric oxide synthase (eNOS) expression and nitric oxide (NO) bioavailability via protein kinase B. However, the putative role of the NO pathway on p66Shc activation remains unclear. This study was designed to elucidate the regulatory role of the eNOS/NO pathway on p66Shc activation.

METHODS AND RESULTS

Incubation of HAEC with oxidized low density lipoprotein (oxLDL) led to phosphorylation of p66Shc at Ser-36, resulting in an enhanced production of superoxide anion (O2-). In the absence of oxLDL, inhibition of eNOS by small interfering RNA or L-NAME, induced p66Shc phosphorylation, suggesting that basal NO production inhibits O2- production. oxLDL-induced, p66Shc-mediated O2- was prevented by eNOS inhibition, suggesting that when cells are stimulated with oxLDL eNOS is a source of reactive oxygen species. Endogenous or exogenous NO donors, prevented p66Shc activation and reduced O2- production. Treatment with tetrahydrobiopterin, an eNOS cofactor, restored eNOS uncoupling, prevented p66Shc activation, and reduced O2- generation. However, late treatment with tetrahydropterin did not yield the same result suggesting that eNOS uncoupling is the primary source of reactive oxygen species.

CONCLUSIONS

The present study reports that in primary cultured HAEC treated with oxLDL, p66Shc-mediated oxidative stress is derived from eNOS uncoupling. This finding contributes novel information on the mechanisms of p66Shc activation and its dual interaction with eNOS underscoring the importance eNOS uncoupling as a putative antioxidant therapeutical target in endothelial dysfunction as observed in cardiovascular disease.

Adaptor protein p66(Shc) mediates hypertension-associated, cyclic stretch-dependent, endothelial damage

Increased cyclic stretch to the vessel wall, as observed in hypertension, leads to endothelial dysfunction through increased free radical production and reduced nitric oxide bioavailability. Genetic deletion of the adaptor protein p66(Shc) protects mice against age-related and hyperglycemia-induced endothelial dysfunction, as well as atherosclerosis and stroke. Furthermore, p66(Shc) mediates vascular dysfunction in hypertensive mice. However, the direct role of p66(Shc) in mediating mechanical force-induced free radical production is unknown; thus, we studied the effect of cyclic stretch on p66(Shc) activation in primary human aortic endothelial cells and aortic endothelial cells isolated from normotensive and hypertensive rats. Exposure of human aortic endothelial cells to cyclic stretch led to a stretch- and time-dependent p66(Shc) phosphorylation at Ser36 downstream of integrin α5β1 and c-Jun N-terminal kinase. In parallel, nicotinamide adenine dinucleotide phosphate oxidase activation, as well as production of reactive oxygen species, increased, whereas nitric oxide bioavailability decreased. Silencing of p66(Shc) blunted stretch-increased superoxide anion production and nicotinamide adenine dinucleotide phosphate oxidase activation and restored nitric oxide bioavailability. In line with the above, activation of p66(Shc) increased in isolated aortic endothelial cells of spontaneously hypertensive rats compared with normotensive ones. Pathological stretch by activating integrin α5β1 and c-Jun N-terminal kinase phosphorylates p66(Shc) at Ser36, augments reactive oxygen species production via nicotinamide adenine dinucleotide phosphate oxidase, and in turn reduces nitric oxide bioavailability. This novel molecular pathway may be relevant for endothelial dysfunction and vascular disease in hypertension.

Effect of AST on age-associated changes of vocal folds in a rat model

OBJECTIVES/HYPOTHESIS

Reactive oxygen species (ROS) are associated with aging. Astaxanthin (AST) is a strong antioxidant and has been reported to prevent various ROS-induced diseases. In the current study, we investigated the effect of AST on age-associated histological and mRNA changes of vocal folds.

STUDY DESIGN

Prospective animal experiment with control.

METHODS

Six-month-old Sprague-Dawley rats were fed on a normal powder diet with 0.01% (w/w) AST (aged AST-treated group) or without AST (aged sham-treated group). After 12 months of feeding, the larynges were harvested for histology, immunohistochemical detection of 4-hydroxy-2-nonenal (4-HNE), and quantitative real-time polymerase chain reaction for basic fibroblast growth factor (bFGF) and hepatocyte growth factor (HGF). Thirteen-week-old rats were used as a young control group (young group).

RESULTS

The expression of 4-HNE, an oxidative stress marker, significantly increased in the two aged groups compared with the young group. Histological examination showed that the deposition of hyaluronic acid in the lamina propria (LP) was significantly reduced in the aged sham-treated group compared with the young group, but no significant difference was observed between the aged AST-treated group and the young group. There were no significant differences in the mRNA expression of bFGF and HGF between the aged AST-treated group and the young group, although the expression of these genes was significantly reduced in the aged sham-treated group as compared with the young group.

CONCLUSIONS

These results suggest that AST has the potential to attenuate age-associated changes of vocal folds.

Energy restriction ameliorates metabolic syndrome-induced cavernous tissue structural modifications in aged rats

High-fat (HF) diet regular intake along life highly contributes to vascular dysfunction and to an increment in prevalence of metabolic syndrome (MetS) and erectile dysfunction (ED), a surrogate symptom of occult vascular disease, in the elderly. However, little is known about the effects of energy restriction (ER) alone/or after an HF-feeding period. We show here that in male Sprague-Dawley rats, 16 months of HF-diet consumption led to an increase in body adiposity, blood pressure, lipidemia, C-reactive protein, and insulin resistance and to hypoadiponectinemia, conditions that cluster in MetS. In addition, this treatment strongly favored collagen deposition in cavernous tissue and myocardium. Conversely, for the same time period, the ingestion of 75 % of ad libitum energy intake by controls (ER) extensively counteracted these outcomes. The impact of 6-month ER after 10-month HF period was also analyzed, and despite the decrease in body weight, adiposity, blood pressure, lipidemia, and C-reactive protein and improvement of insulin sensitivity, no differences were observed either in adiponectin blood levels or in retroperitoneal fat pad mass. Moreover, this treatment led to a reduction in cavernous tissue collagen deposition, but not in the myocardium, and evidenced differential mobilization of adipose tissue accretions. The data show the ability of HF diet to cause MetS and produce unwanted effects on myocardium and corpora vascular structure. They also indicate that these consequences are preventable upon ER diet starting early, but not later, in life.

A new anti-ageing strategy focused on prevention of arterial ageing in the middle-aged population

Ageing is a progressive process that according to available knowledge cannot be effectively reversed, slowed or stopped. Here we propose a new anti-ageing approach that may lead to the design of effective therapeutic intervention. First, we hypothesize that the "organ system" oriented anti-ageing approach represents a better anti-ageing target than the "whole body" or "cellular ageing" concepts. The arterial system is the most suitable target, as it interconnects all the organs in the body, thus influencing them all. Second, we propose that an anti-ageing approach could be more successful in early than late ageing stages; middle-aged people seem to be the most appropriate candidates. Third, we believe that instead of searching for new medication, we should rely on already established medications with beneficial effects on the arterial wall. Renin-angiotensin system inhibitors and statins fulfill these criteria and are potential cornerstones of the new approach. The fourth hypothesis is based on the concept that in the early stages of arterial ageing only slight injury is present and therefore subtherapeutic, low-dose treatment would be effective. Fifth, we hypothesize that slight initial age-related arterial wall changes are reversible and could be corrected by a short-term (one month) treatment. Sixth, we hypothesize that the effects would be present for a certain period of time even after treatment termination. The listed assumptions combined represent the basis for a new, original anti-ageing approach - a subtherapeutic low-dose combination of a renin-angiotensin system inhibitor and a statin for one month (followed by approximately 6-12 months without treatment) could delay or even reverse the arterial ageing process and consequently decrease the incidence of cardiovascular disorders.

A new mouse model of dry eye disease: oxidative stress affects functional decline in the lacrimal gland

PURPOSE

Oxidative damage and inflammation are proposed to be involved in the age-related functional decline of lacrimal glands. The molecular mechanism(s) of how oxidative stress affects the secretory function of lacrimal glands was investigated because this is currently unclear.

METHODS

We used a novel mev-1 conditional transgenic mouse model (Tet-mev-1) with a modified tetracycline system. The mev-1 gene encodes the cytochrome b560 large subunit of succinate-ubiquinone oxidoreductase in complex II of mitochondria.

RESULTS

Expression of the mev-1 gene induced excessive oxidative stress associated with ocular surface epithelial damage and a decrease in aqueous secretory function. Tear volume in Tet-mev-1 mice was lower than in wild-type mice, and histopathological analyses showed the hallmarks of lacrimal gland inflammation by intense mononuclear leukocytic infiltration and fibrosis in the lacrimal gland of Tet-mev-1 mice.

CONCLUSIONS

This new model provides evidence that mitochondria-induced oxidative damage in the lacrimal gland induces lacrimal dysfunction, resulting in dry eye disease. Our findings strongly suggest that oxidative stress can be a causative factor in the development of dry eye disease.

Methods for structuring scientific knowledge from many areas related to aging research

Aging and age-related disease represents a substantial quantity of current natural, social and behavioral science research efforts. Presently, no centralized system exists for tracking aging research projects across numerous research disciplines. The multidisciplinary nature of this research complicates the understanding of underlying project categories, the establishment of project relations, and the development of a unified project classification scheme. We have developed a highly visual database, the International Aging Research Portfolio (IARP), available at AgingPortfolio.org to address this issue. The database integrates information on research grants, peer-reviewed publications, and issued patent applications from multiple sources. Additionally, the database uses flexible project classification mechanisms and tools for analyzing project associations and trends. This system enables scientists to search the centralized project database, to classify and categorize aging projects, and to analyze the funding aspects across multiple research disciplines. The IARP is designed to provide improved allocation and prioritization of scarce research funding, to reduce project overlap and improve scientific collaboration thereby accelerating scientific and medical progress in a rapidly growing area of research. Grant applications often precede publications and some grants do not result in publications, thus, this system provides utility to investigate an earlier and broader view on research activity in many research disciplines. This project is a first attempt to provide a centralized database system for research grants and to categorize aging research projects into multiple subcategories utilizing both advanced machine algorithms and a hierarchical environment for scientific collaboration.