Development of progressive aortic vasculopathy in a rat model of aging

Role of CaMKII in diabetes induced vascular injury and its interaction with anti-diabetes therapy

Diabetes mellitus is a metabolic disorder denoted by chronic hyperglycemia that drives maladaptive structural changes and functional damage to the vasculature. Attenuation of this pathological remodeling of blood vessels remains an unmet target owing to paucity of information on the metabolic signatures of this process. Ca2+/calmodulin-dependent kinase II (CaMKII) is expressed in the vasculature and is implicated in the control of blood vessels homeostasis. Recently, CaMKII has attracted a special attention in view of its chronic upregulated activity in diabetic tissues, yet its role in the diabetic vasculature remains under investigation.This review highlights the physiological and pathological actions of CaMKII in the diabetic vasculature, with focus on the control of the dialogue between endothelial (EC) and vascular smooth muscle cells (VSMC). Activation of CaMKII enhances EC and VSMC proliferation and migration, and increases the production of extracellular matrix which leads to maladaptive remodeling of vessels. This is manifested by activation of genes/proteins implicated in the control of the cell cycle, cytoskeleton organization, proliferation, migration, and inflammation. Endothelial dysfunction is paralleled by impaired nitric oxide signaling, which is also influenced by CaMKII signaling (activation/oxidation). The efficiency of CaMKII inhibitors is currently being tested in animal models, with a focus on the genetic pathways involved in the regulation of CaMKII expression (microRNAs and single nucleotide polymorphisms). Interestingly, studies highlight an interaction between the anti-diabetic drugs and CaMKII expression/activity which requires further investigation. Together, the studies reviewed herein may guide pharmacological approaches to improve health-related outcomes in patients with diabetes.

Extracellular Matrix in Aging Aorta

The aging population is booming all over the world and arterial aging causes various age-associated pathologies such as cardiovascular diseases (CVDs). The aorta is the largest elastic artery, and transforms pulsatile flow generated by the left ventricle into steady flow to maintain circulation in distal tissues and organs. Age-associated structural and functional changes in the aortic wall such as dilation, tortuousness, stiffening and losing elasticity hamper stable peripheral circulation, lead to tissue and organ dysfunctions in aged people. The extracellular matrix (ECM) is a three-dimensional network of macromolecules produced by resident cells. The composition and organization of key ECM components determine the structure-function relationships of the aorta and therefore maintaining their homeostasis is critical for a healthy performance. Age-associated remodeling of the ECM structural components, including fragmentation of elastic fibers and excessive deposition and crosslinking of collagens, is a hallmark of aging and leads to functional stiffening of the aorta. In this mini review, we discuss age-associated alterations of the ECM in the aortic wall and shed light on how understanding the mechanisms of aortic aging can lead to the development of efficient strategy for aortic pathologies and CVDs.

Bisphenol A Induces Accelerated Cell Aging in Murine Endothelium

Bisphenol A (BPA) is a widespread endocrine disruptor affecting many organs and systems. Previous work in our laboratory demonstrated that BPA could induce death due to necroptosis in murine aortic endothelial cells (MAECs). This work aims to evaluate the possible involvement of BPA-induced senescence mechanisms in endothelial cells. The β-Gal assays showed interesting differences in cell senescence at relatively low doses (100 nM and 5 µM). Western blots confirmed that proteins involved in senescence mechanisms, p16 and p21, were overexpressed in the presence of BPA. In addition, the UPR (unfolding protein response) system, which is part of the senescent phenotype, was also explored by Western blot and qPCR, confirming the involvement of the PERK-ATF4-CHOP pathway (related to pathological processes). The endothelium of mice treated with BPA showed an evident increase in the expression of the proteins p16, p21, and CHOP, confirming the results observed in cells. Our results demonstrate that oxidative stress induced by BPA leads to UPR activation and senescence since pretreatment with N-acetylcysteine (NAC) in BPA-treated cells reduced the percentage of senescent cells prevented the overexpression of proteins related to BPA-induced senescence and reduced the activation of the UPR system. The results suggest that BPA participates actively in accelerated cell aging mechanisms, affecting the vascular endothelium and promoting cardiovascular diseases.

Molecular footprint of Medawar's mutation accumulation process in mammalian aging

Medawar's mutation accumulation hypothesis explains aging by the declining force of natural selection with age: Slightly deleterious germline mutations expressed in old age can drift to fixation and thereby lead to aging‐related phenotypes. Although widely cited, empirical evidence for this hypothesis has remained limited. Here, we test one of its predictions that genes relatively highly expressed in old adults should be under weaker purifying selection than genes relatively highly expressed in young adults. Combining 66 transcriptome datasets (including 16 tissues from five mammalian species) with sequence conservation estimates across mammals, here we report that the overall conservation level of expressed genes is lower at old age compared to young adulthood. This age‐related decrease in transcriptome conservation (ADICT) is systematically observed in diverse mammalian tissues, including the brain, liver, lung, and artery, but not in others, most notably in the muscle and heart. Where observed, ADICT is driven partly by poorly conserved genes being up‐regulated during aging. In general, the more often a gene is found up‐regulated with age among tissues and species, the lower its evolutionary conservation. Poorly conserved and up‐regulated genes have overlapping functional properties that include responses to age‐associated tissue damage, such as apoptosis and inflammation. Meanwhile, these genes do not appear to be under positive selection. Hence, genes contributing to old age phenotypes are found to harbor an excess of slightly deleterious alleles, at least in certain tissues. This supports the notion that genetic drift shapes aging in multicellular organisms, consistent with Medawar's mutation accumulation hypothesis.

Cardiac and Renal Delayed Effects of Acute Radiation Exposure: Organ Differences in Vasculopathy, Inflammation, Senescence and Oxidative Balance

We have previously shown significant pathology in the heart and kidney of murine hematopoietic-acute radiation syndrome (H-ARS) survivors of 8.7-9.0 Gy total-body irradiation (TBI). The goal of this study was to determine temporal relationships in the development of vasculopathy and the progression of renal and cardiovascular delayed effects of acute radiation exposure (DEARE) at TBI doses less than 9 Gy and to elucidate the potential roles of senescence, inflammation and oxidative stress. Our results show significant loss of endothelial cells in coronary arteries by 4 months post-TBI (8.53 or 8.72 Gy of gamma radiation). This loss precedes renal dysfunction and interstitial fibrosis and progresses to abnormalities in the arterial media and adventitia and loss of coronary arterioles. Major differences in radiation-induced pathobiology exist between the heart and kidney in terms of vasculopathy progression and also in indices of inflammation, senescence and oxidative imbalance. The results of this work suggest a need for different medical countermeasures for multiple targets in different organs and at various times after acute radiation injury to prevent the progression of DEARE.

Mechanisms of Dysfunction in the Aging Vasculature and Role in Age-Related Disease

Advancing age promotes cardiovascular disease (CVD), the leading cause of death in the United States and many developed nations. Two major age-related arterial phenotypes, large elastic artery stiffening and endothelial dysfunction, are independent predictors of future CVD diagnosis and likely are responsible for the development of CVD in older adults. Not limited to traditional CVD, these age-related changes in the vasculature also contribute to other age-related diseases that influence mammalian health span and potential life span. This review explores mechanisms that influence age-related large elastic artery stiffening and endothelial dysfunction at the tissue level via inflammation and oxidative stress and at the cellular level via Klotho and energy-sensing pathways (AMPK [AMP-activated protein kinase], SIRT [sirtuins], and mTOR [mammalian target of rapamycin]). We also discuss how long-term calorie restriction-a health span- and life span-extending intervention-can prevent many of these age-related vascular phenotypes through the prevention of deleterious alterations in these mechanisms. Lastly, we discuss emerging novel mechanisms of vascular aging, including senescence and genomic instability within cells of the vasculature. As the population of older adults steadily expands, elucidating the cellular and molecular mechanisms of vascular dysfunction with age is critical to better direct appropriate and measured strategies that use pharmacological and lifestyle interventions to reduce risk of CVD within this population.

Senescent cells: a therapeutic target for cardiovascular disease

Cellular senescence, a major tumor-suppressive cell fate, has emerged from humble beginnings as an in vitro phenomenon into recognition as a fundamental mechanism of aging. In the process, senescent cells have attracted attention as a therapeutic target for age-related diseases, including cardiovascular disease (CVD), the leading cause of morbidity and mortality in the elderly. Given the aging global population and the inadequacy of current medical management, attenuating the health care burden of CVD would be transformative to clinical practice. Here, we review the evidence that cellular senescence drives CVD in a bimodal fashion by both priming the aged cardiovascular system for disease and driving established disease forward. Hence, the growing field of senotherapy (neutralizing senescent cells for therapeutic benefit) is poised to contribute to both prevention and treatment of CVD.

In Development-A New Paradigm for Understanding Vascular Disease

Under physiological conditions, the arterial endothelium exerts a powerful protective influence to maintain vascular homeostasis. However, during the development of vascular disease, these protective activities are lost, and dysfunctional endothelial cells actually promote disease pathogenesis. Numerous investigations have analyzed the characteristics of dysfunctional endothelium with a view to understanding the processes responsible for the dysfunction and to determining their role in vascular pathology. This review adopts an alternate approach: reviewing the mechanisms that contribute to the initial formation of a healthy protective endothelium and on how those mechanisms may be disrupted, precipitating the appearance of dysfunctional endothelial cells and the progression of vascular disease. This approach, which highlights the role of endothelial adherens junctions and vascular endothelial-cadherin in endothelial maturation and endothelial dysfunction, provides new insight into the remarkable biology of this important cell layer and its role in vascular protection and vascular disease.

Galectin-3, osteopontin and successful aging

BACKGROUND

Individuals who reach exceptional longevity (100+ years of age) free of common chronic age diseases (i.e. 'dodgers') arguably represent the paradigm of successful aging in humans. As such, identification of potential biomarkers associated with this phenomenon is of medical interest.

METHODS

We measured serum levels of galectin-3 and osteopontin, both of which have been shown to be linked with major chronic or aging-related disorders in younger populations, in centenarian 'dodgers' (n=81; 40 men; 100-104 years) and healthy controls (n=41; 24 men, 70-80 years).

RESULTS

Both biomarkers showed significantly lower values (p<0.001) in the former (galectin-3: 2.4±1.7 vs. 4.8±2.8 ng/mL; osteopontin: 38.1±27.7 vs. 72.6±33.1 μg/mL). Logistic regression analysis identified the combination of these two biomarkers as a significant predictor variable associated with successful aging regardless of sex (p<0.001). The area under the curve (AUC) classified the ability of galectin-3 and osteopontin to predict the likelihood of successful aging as 'fair' (AUC=0.75) and 'good' (AUC=0.80), respectively. Particularly, the combination of the two biomarkers showed good discriminatory power for successful aging (AUC=0.86), with sensitivity=83% and specificity=74%.

CONCLUSIONS

Lower levels of both galectin-3 and osteopontin are associated with successful aging, representing potential biomarkers of this condition. Our cross-sectional data must be however approached with caution. Further research is necessary to replicate the present preliminary results in other cohorts and to identify the potential use of galectin-3 and osteopontin as potential targets (or at least predictors) in future personalized anti-aging therapies.

Aging and the cardiac collagen matrix: Novel mediators of fibrotic remodelling

Cardiovascular disease is a leading cause of death worldwide and there is a pressing need for new therapeutic strategies to treat such conditions. The risk of developing cardiovascular disease increases dramatically with age, yet the majority of experimental research is executed using young animals. The cardiac extracellular matrix (ECM), consisting predominantly of fibrillar collagen, preserves myocardial integrity, provides a means of force transmission and supports myocyte geometry. Disruptions to the finely balanced control of collagen synthesis, post-synthetic deposition, post-translational modification and degradation may have detrimental effects on myocardial functionality. It is now well established that the aged heart is characterized by fibrotic remodelling, but the mechanisms responsible for this are incompletely understood. Furthermore, studies using aged animal models suggest that interstitial remodelling with disease may be age-dependent. Thus with the identification of new therapeutic strategies targeting fibrotic remodelling, it may be necessary to consider age-dependent mechanisms. In this review, we discuss remodelling of the cardiac collagen matrix as a function of age, whilst highlighting potential novel mediators of age-dependent fibrotic pathways.

Animal models of aging research: implications for human aging and age-related diseases

Aging is characterized by an increasing morbidity and functional decline that eventually results in the death of an organism. Aging is the largest risk factor for numerous human diseases, and understanding the aging process may thereby facilitate the development of new treatments for age-associated diseases. The use of humans in aging research is complicated by many factors, including ethical issues; environmental and social factors; and perhaps most importantly, their long natural life span. Although cellular models of human disease provide valuable mechanistic information, they are limited in that they may not replicate the in vivo biology. Almost all organisms age, and thus animal models can be useful for studying aging. Herein, we review some of the major models currently used in aging research and discuss their benefits and pitfalls, including interventions known to extend life span and health span. Finally, we conclude by discussing the future of animal models in aging research.

Cellular and molecular biology of aging endothelial cells

Cardiovascular disease (CVD) is the leading cause of death in the United States and aging is a major risk factor for CVD development. One of the major age-related arterial phenotypes thought to be responsible for the development of CVD in older adults is endothelial dysfunction. Endothelial function is modulated by traditional CVD risk factors in young adults, but advancing age is independently associated with the development of vascular endothelial dysfunction. This endothelial dysfunction results from a reduction in nitric oxide bioavailability downstream of endothelial oxidative stress and inflammation that can be further modulated by traditional CVD risk factors in older adults. Greater endothelial oxidative stress with aging is a result of augmented production from the intracellular enzymes NADPH oxidase and uncoupled eNOS, as well as from mitochondrial respiration in the absence of appropriate increases in antioxidant defenses as regulated by relevant transcription factors, such as FOXO. Interestingly, it appears that NFkB, a critical inflammatory transcription factor, is sensitive to this age-related endothelial redox change and its activation induces transcription of pro-inflammatory cytokines that can further suppress endothelial function, thus creating a vicious feed-forward cycle. This review will discuss the two macro-mechanistic processes, oxidative stress and inflammation, that contribute to endothelial dysfunction with advancing age as well as the cellular and molecular events that lead to the vicious cycle of inflammation and oxidative stress in the aged endothelium. Other potential mediators of this pro-inflammatory endothelial phenotype are increases in immune or senescent cells in the vasculature. Of note, genomic instability, telomere dysfunction or DNA damage has been shown to trigger cell senescence via the p53/p21 pathway and result in increased inflammatory signaling in arteries from older adults. This review will discuss the current state of knowledge regarding the emerging concepts of senescence and genomic instability as mechanisms underlying oxidative stress and inflammation in the aged endothelium. Lastly, energy sensitive/stress resistance pathways (SIRT-1, AMPK, mTOR) are altered in endothelial cells and/or arteries with aging and these pathways may modulate endothelial function via key oxidative stress and inflammation-related transcription factors. This review will also discuss what is known about the role of "energy sensing" longevity pathways in modulating endothelial function with advancing age. With the growing population of older adults, elucidating the cellular and molecular mechanisms of endothelial dysfunction with age is critical to establishing appropriate and measured strategies to utilize pharmacological and lifestyle interventions aimed at alleviating CVD risk. This article is part of a Special Issue entitled "SI: CV Aging".

Efficacy of female rat models in translational cardiovascular aging research

Cardiovascular disease is the leading cause of death in women in the United States. Aging is a primary risk factor for the development of cardiovascular disease as well as cardiovascular-related morbidity and mortality. Aging is a universal process that all humans undergo; however, research in aging is limited by cost and time constraints. Therefore, most research in aging has been done in primates and rodents; however it is unknown how well the effects of aging in rat models translate into humans. To compound the complication of aging gender has also been indicated as a risk factor for various cardiovascular diseases. This review addresses the systemic pathophysiology of the cardiovascular system associated with aging and gender for aging research with regard to the applicability of rat derived data for translational application to human aging.

The Effect of Ageing on Vascular Smooth Muscle Cell Behaviour--A Mini-Review

Ageing is a prominent risk factor for atherosclerosis and cardiovascular disease. Vascular smooth muscle cells (VSMCs) are an integral part of atherosclerotic plaque formation, progression and subsequent rupture. Emerging evidence suggests that VSMC behaviour is modified by age, which in turn may affect disease outcome in the elderly. In this review, we discuss the effect of age on VSMC behaviour, proliferation, migration, apoptosis, inflammation, extracellular matrix synthesis and calcification. In addition, we discuss the multiple signalling factors underlying these behavioural changes including angiotensin-II, matrix metalloproteinases, monocyte chemotactic protein-1, and transforming growth factor-β1. Understanding the molecular processes underpinning altered VSMC behaviour with age, may lead to the identification of novel therapeutic targets for suppressing atherosclerosis in the elderly population.

Analysis of oxidative stress enzymes and structural and functional proteins on human aortic tissue from different aortopathies

The role of oxidative stress in different aortopathies is evaluated. Thirty-two tissue samples from 18 men and 14 women were divided into: 4 control (C) subjects, 11 patients with systemic arterial hypertension (SAH), 4 with variants of Marfan's syndrome (MV), 9 with Marfan's syndrome (M), 2 with Turner's syndrome, and 2 with Takayasu's arteritis (TA). Aorta fragments were homogenized. Lipoperoxidation (LPO), copper-zinc and manganese superoxide dismutase (Mn and Cu-Zn-SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), endothelial nitric oxide synthase (eNOS), nitrates and nitrites (NO3(-)/NO2(-)), and type IV collagen, and laminin were evaluated. There was an increase in Mn- and Cu-Zn-SOD activity in SAH, MV, M, and Turner's syndrome. There was also an increase in CAT activity in M and Turner' syndrome. GPx and GST activity decreased and LPO increased in all groups. eNOS was decreased in SAH, MV, and M and NO3 (-)/NO2 (-) were increased in SAH and TA. Type IV collagen was decreased in Turner's syndrome and TA. Laminin γ-1 was decreased in MV and increased in M. In conclusion, similarities and differences in oxidative stress in the different aortopathies studied including pathologies with aneurysms were found with alterations in SOD, CAT, GPx, GST, and eNOS activity that modify subendothelial basement membrane proteins.

Myocardial extracellular matrix: an ever-changing and diverse entity

The cardiac extracellular matrix (ECM) is a complex architectural network consisting of structural and nonstructural proteins, creating strength and plasticity. The nonstructural compartment of the ECM houses a variety of proteins, which are vital for ECM plasticity, and can be divided into 3 major groups: glycoproteins, proteoglycans, and glycosaminoglycans. The common denominator for these groups is glycosylation, which refers to the decoration of proteins or lipids with sugars. This review will discuss the fundamental role of the matrix in cardiac development, homeostasis, and remodeling, from a glycobiology point of view. Glycoproteins (eg, thrombospondins, secreted protein acidic and rich in cysteine, tenascins), proteoglycans (eg, versican, syndecans, biglycan), and glycosaminoglycans (eg, hyaluronan, heparan sulfate) are upregulated on cardiac injury and regulate key processes in the remodeling myocardium such as inflammation, fibrosis, and angiogenesis. Albeit some parallels can be made regarding the processes these proteins are involved in, their specific functions are extremely diverse. In fact, under varying conditions, individual proteins can even have opposing functions, making spatiotemporal contribution of these proteins in the rearrangement of multifaceted ECM very hard to grasp. Alterations of protein characteristics by the addition of sugars may explain the immense, yet tightly regulated, variability of the remodeling cardiac matrix. Understanding the role of glycosylation in altering the ultimate function of glycoproteins, proteoglycans, and glycosaminoglycans in the myocardium may lead to the development of new biochemical structures or compounds with great therapeutic potential for patients with heart disease.

Molecular basis for impaired collateral artery growth in the spontaneously hypertensive rat: insight from microarray analysis

Analysis of global gene expression in mesenteric control and collateral arteries was used to investigate potential molecules, pathways, and mechanisms responsible for impaired collateral growth in the Spontaneously Hypertensive Rat (SHR). A fundamental difference was observed in overall gene expression pattern in SHR versus Wistar Kyoto (WKY) collaterals; only 6% of genes altered in collaterals were similar between rat strains. Ingenuity® Pathway Analysis (IPA) identified major differences between WKY and SHR in networks and biological functions related to cell growth and proliferation and gene expression. In SHR control arteries, several mechano-sensitive and redox-dependent transcription regulators were downregulated including JUN (-5.2×, P = 0.02), EGR1 (-4.1×, P = 0.01), and NFĸB1 (-1.95×, P = 0.04). Predicted binding sites for NFĸB and AP-1 were present in genes altered in WKY but not SHR collaterals. Immunostaining showed increased NFĸB nuclear translocation in collateral arteries of WKY and apocynin-treated SHR, but not in untreated SHR. siRNA for the p65 subunit suppressed collateral growth in WKY, confirming a functional role of NFkB. Canonical pathways identified by IPA in WKY but not SHR included nitric oxide and renin-angiotensin system signaling. The angiotensin type 1 receptor (AGTR1) exhibited upregulation in WKY collaterals, but downregulation in SHR; pharmacological blockade of AGTR1 with losartan prevented collateral luminal expansion in WKY. Together, these results suggest that collateral growth impairment results from an abnormality in a fundamental regulatory mechanism that occurs at a level between signal transduction and gene transcription and implicate redox-dependent modulation of mechano-sensitive transcription factors such as NFĸB as a potential mechanism.

Matricellular proteins in cardiac adaptation and disease

The term matricellular proteins describes a family of structurally unrelated extracellular macromolecules that, unlike structural matrix proteins, do not play a primary role in tissue architecture, but are induced following injury and modulate cell-cell and cell-matrix interactions. When released to the matrix, matricellular proteins associate with growth factors, cytokines, and other bioactive effectors and bind to cell surface receptors transducing signaling cascades. Matricellular proteins are upregulated in the injured and remodeling heart and play an important role in regulation of inflammatory, reparative, fibrotic and angiogenic pathways. Thrombospondin (TSP)-1, -2, and -4 as well as tenascin-C and -X secreted protein acidic and rich in cysteine (SPARC), osteopontin, periostin, and members of the CCN family (including CCN1 and CCN2/connective tissue growth factor) are involved in a variety of cardiac pathophysiological conditions, including myocardial infarction, cardiac hypertrophy and fibrosis, aging-associated myocardial remodeling, myocarditis, diabetic cardiomyopathy, and valvular disease. This review discusses the properties and characteristics of the matricellular proteins and presents our current knowledge on their role in cardiac adaptation and disease. Understanding the role of matricellular proteins in myocardial pathophysiology and identification of the functional domains responsible for their actions may lead to design of peptides with therapeutic potential for patients with heart disease.

Chronic oral administration of the arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH) improves erectile function in aged rats

Arginase expression and activity have been noted to be heightened in conditions associated with erectile dysfunction, including aging. Previously, arginase inhibition by chronic administration of the arginase inhibitor 2-(S)-amino-6-boronohexanoic acid (ABH) has been shown to improve endothelial dysfunction in aged rats. The objective of this study was to assess whether chronic oral ABH administration affects cavernosal erectile function. Rats were divided into 4 groups: young control, young treated with arginase inhibitor, aged control, and aged treated with arginase inhibitor. Arginase activity was measured and presented as a proportion of young untreated rats. In vivo erectile responses to cavernous nerve stimulation were measured in all cohorts. The cavernous nerve was stimulated with a graded electrical stimulus, and the intracavernosal/mean arterial pressure ratios and total intracavernosal pressure were recorded. Arginase activity was elevated in the aged rats compared with young controls; however, arginase activity was significantly decreased in aged rats treated with ABH. With the addition of ABH, erectile responses improved in the aged rats (P < .05). Oral inhibition of arginase with ABH results in improved erectile function in aged rats, resulting in erectile hemodynamics similar to young rats. This represents the first documentation of systemic arginase inhibition positively affecting corporal cavernosal function.

Distinct roles of trauma and transfusion in induction of immune modulation after injury

BACKGROUND

Trauma and transfusion can both alter immunity, and while transfusions are common among traumatically injured patients, few studies have examined their combined effects on immunity.

STUDY DESIGN AND METHODS

We tracked the plasma levels of 41 immunomodulatory proteins in 56 trauma patients from time of injury up to 1 year later. In addition, a murine model was developed to distinguish between the effects of transfusion and underlying injury and blood loss.

RESULTS

Thirty-one of the proteins had a significant change over time after traumatic injury, with a mixed early response that was predominantly anti-inflammatory followed by a later increase in proteins involved in wound healing and homeostasis. Results from the murine model revealed similar cytokine responses to humans. In mice, trauma and hemorrhage caused early perturbations in a number of the pro- and anti-inflammatory mediators measured, and transfusion blunted early elevations in interleukin (IL)-6, IL-10, matrix metalloproteinase-9, and interferon-γ. Transfusion caused or exacerbated changes in monocyte chemotactic protein-1, IL-1α, IL-5, IL-15, and soluble E-selectin. Finally, trauma and hemorrhage alone increased CXCL1 and IL-13.

CONCLUSIONS

This work provides a detailed characterization of the major shift in the immunologic environment in response to trauma and transfusion and clarifies which immune mediators are affected by trauma and hemorrhage and which by transfusion.

Dynamic regulation of vascular myosin light chain (MYL9) with injury and aging

BACKGROUND

Aging-associated changes in the cardiovascular system increase the risk for disease development and lead to profound alterations in vascular reactivity and stiffness. Elucidating the molecular response of arteries to injury and age will help understand the exaggerated remodeling of aging vessels.

METHODOLOGY/PRINCIPAL FINDINGS

We studied the gene expression profile in a model of mechanical vascular injury in the iliac artery of aging (22 months old) and young rats (4 months old). We investigated aging-related variations in gene expression at 30 min, 3 d and 7 d post injury. We found that the Myosin Light Chain gene (MYL9) was the only gene differentially expressed in the aged versus young injured arteries at all time points studied, peaking at day 3 after injury (4.6 fold upregulation (p<0.05) in the smooth muscle cell layers. We confirmed this finding on an aging aortic microarray experiment available through NCBI's GEO database. We found that Myl9 was consistently upregulated with age in healthy rat aortas. To determine the arterial localization of Myl9 with age and injury, we performed immunohistochemistry for Myl9 in rat iliac arteries and found that in healthy and injured (30 days post injury) arteries, Myl9 expression increased with age in the endothelial layers.

CONCLUSIONS/SIGNIFICANCE

The consistent upregulation of the myosin light chain protein (Myl9) with age and injury in arterial tissue draws attention to the increased vascular permeability and to the age-caused predisposition to arterial constriction after balloon angioplasty.

Age-related changes in immune function: effect on airway inflammation

Immunosenescence is defined as changes in the innate and adaptive immune response associated with increased age. The clinical consequences of immunosenescence include increased susceptibility to infection, malignancy and autoimmunity, decreased response to vaccination, and impaired wound healing. However, there are several immune alterations that might facilitate persistence of asthma into late adulthood or development of asthma after the age of 50 to 60 years. Asthma in older patients is not uncommon, and this is a growing population as the average lifespan increases. Specific innate changes that might affect severity of asthma in older patients or be involved in the development of late-onset asthma include impaired mucociliary clearance and changes in airway neutrophil, eosinophil, and mast cell numbers and function. Additionally, age-related altered antigen presentation and decreased specific antibody responses might increase the risk of respiratory tract infections. Respiratory tract infections exacerbate asthma in older patients and possibly play a role in the pathogenesis of late-onset asthma. Furthermore, cytokine profiles might be modified with aging, with some investigators suggesting a trend toward T(H)2 cytokine expression. This review examines specific innate and adaptive immune responses affected by aging that might affect the inflammatory response in older adults with asthma.

Age-related changes in redox signaling and VSMC function

Epidemiological studies have shown that advancing age is associated with an increased prevalence of cardiovascular disease (CVD). Vascular smooth muscle cells (VSMC) comprise the major arterial cell population, and changes in VSMC behavior, function, and redox status with age contribute to alterations in vascular remodeling and cell signaling. Over two decades of work on aged animal models provide support for age-related changes in VSMC and/or arterial tissues. Enhanced production of reactive oxygen species (ROS) and insufficient removal by scavenging systems are hallmarks of vascular aging. VSMC proliferation and migration are core processes in vascular remodeling and influenced by growth factors and signaling networks. The intrinsic link between gene regulation and aging often relates directly to transcription factors and their regulatory actions. Modulation of growth factor signaling leads to up- or downregulation of transcription factors that control expression of genes associated with VSMC proliferation, inflammation, and ROS production. Four major signaling pathways related to the transcription factors, AP-1, NF-kappaB, FoxO, and Nrf2, will be reviewed. Knowledge of age-related changes in signaling pathways in VSMC that lead to alterations in cell behavior and function consistent with disease progression may help in efforts to attenuate age-related CVD, such as atherosclerosis.

Arginase inhibition restores NOS coupling and reverses endothelial dysfunction and vascular stiffness in old rats

There is increasing evidence that upregulation of arginase contributes to impaired endothelial function in aging. In this study, we demonstrate that arginase upregulation leads to endothelial nitric oxide synthase (eNOS) uncoupling and that in vivo chronic inhibition of arginase restores nitroso-redox balance, improves endothelial function, and increases vascular compliance in old rats. Arginase activity in old rats was significantly increased compared with that shown in young rats. Old rats had significantly lower nitric oxide (NO) and higher superoxide (O2(-)) production than young. Acute inhibition of both NOS, with N(G)-nitro-l-arginine methyl ester, and arginase, with 2S-amino- 6-boronohexanoic acid (ABH), significantly reduced O2(-) production in old rats but not in young. In addition, the ratio of eNOS dimer to monomer in old rats was significantly decreased compared with that shown in young rats. These results suggest that eNOS was uncoupled in old rats. Although the expression of arginase 1 and eNOS was similar in young and old rats, inducible NOS (iNOS) was significantly upregulated. Furthermore, S-nitrosylation of arginase 1 was significantly elevated in old rats. These findings support our previously published finding that iNOS nitrosylates and activates arginase 1 (Santhanam et al., Circ Res 101: 692-702, 2007). Chronic arginase inhibition in old rats preserved eNOS dimer-to-monomer ratio and significantly reduced O2(-) production and enhanced endothelial-dependent vasorelaxation to ACh. In addition, ABH significantly reduced vascular stiffness in old rats. These data indicate that iNOS-dependent S-nitrosylation of arginase 1 and the increase in arginase activity lead to eNOS uncoupling, contributing to the nitroso-redox imbalance, endothelial dysfunction, and vascular stiffness observed in vascular aging. We suggest that arginase is a viable target for therapy in age-dependent vascular stiffness.

Echocardiographic and histological assessment of age-related valvular changes in normal rats

Aging is associated with morphologic and functional alterations of the rat's left ventricle. However, the time-course of valvular function and morphology in normal aging rats has not yet been studied. For this purpose, 30 male Wistar rats (318 +/- 5g, 10 weeks old) underwent serial echocardiograms for 58 weeks under sodium pentobarbital 50 mg/kg IP anesthetization followed by necropsy. Histopathology was also performed in two additional groups of 10 rats at 10 and 30 weeks of age. Regurgitations were considered as any retrograde flow on 2-D or M-mode color Doppler echocardiography. Tricuspid regurgitation was already found at 10 weeks of age and became more frequent with age. Pulmonary, mitral and aortic regurgitation was seldom observed at 10 weeks but became more frequent after 30 weeks. For the mitral and aortic valve, this was also associated with an increase in valvular thickness because of nodular or segmental myxoid leaflet changes. The severity of valvular regurgitations did not increase with age. In conclusion, aging leads to morphologic and functional valvular changes in normal rats. This is important when investigating models of valvular heart disease in small animals.

Age-related differences in insulin-like growth factor-1 receptor signaling regulates Akt/FOXO3a and ERK/Fos pathways in vascular smooth muscle cells

Advanced age is a major risk factor for atherosclerosis, but how aging per se influences pathogenesis is not clear. Insulin-like growth factor-1 receptor (IGF-1R) promotes aortic vascular smooth muscle cell (VSMC) growth, migration, and extracellular matrix formation, but how IGF-1R signaling changes with age in VSMC is not known. We previously found age-related differences in the activation of Akt/FOXO3a and ERK1/2 pathways in VSMC, but the upstream signaling remains unclear. Using explanted VSMC from Fischer 344/Brown Norway F1 hybrid rats shown to display age-related vascular pathology similar to humans, we compared IGF-1R expression in early passages of VSMC and found a constitutive activation of IGF-1R in VSMC from old compared to young rats, including IGF-1R expression and its tyrosine kinase activity. The link between IGF-1R activation and the Akt/FOXO3a and ERK pathways was confirmed through the induction of IGF-1R with IGF-1 in young cells and attenuation of IGF-1R with an inhibitor in old cells. The effects of three kinase inhibitors: AG1024, LY294002, and TCN, were compared in VSMC from old rats to differentiate IGF-1R from other upstream signaling that could also regulate the Akt/FOXO and ERK pathways. Genes for p27kip-1, catalase and MnSOD, which play important roles in the control of cell cycle arrest and stress resistance, were found to be FOXO3a-targets based on FOXO3a-siRNA treatment. Furthermore, IGF-1R signaling modulated these genes through activation of the Akt/FOXO3a pathway. Therefore, activation of IGF-1R signaling influences VSMC function in old rats and may contribute to the increased risk for atherosclerosis.