Age-related changes affecting atherosclerotic risk. Potential for pharmacological intervention

Inflammation and cardiovascular disease: From mechanisms to therapeutics

Inflammation constitutes a complex, highly conserved cascade of molecular and cellular events. Inflammation has been labeled as “the fire within,” is highly regulated, and is critical to host defense and tissue repair. In general, inflammation is beneficial and has evolved to promote survival. However, inflammation can also be maladaptive when chronically activated and sustained, leading to progressive tissue injury and reduced survival. Examples of a maladaptive response include rheumatologic disease and atherosclerosis. Despite evidence gathered by Virchow over 100 years ago showing that inflammatory white cells play a role in atherogenesis, atherosclerosis was until recently viewed as a disease of passive cholesterol accumulation in the subendothelial space. This view has been supplanted by considerable basic scientific and clinical evidence demonstrating that every step of atherogenesis, from the development of endothelial cell dysfunction to foam cell formation, plaque formation and progression, and ultimately plaque rupture stemming from architectural instability, is driven by the cytokines, interleukins, and cellular constituents of the inflammatory response. Herein we provide an overview of the role of inflammation in atherosclerotic cardiovascular disease, discuss the predictive value of various biomarkers involved in inflammation, and summarize recent clinical trials that evaluated the capacity of various pharmacologic interventions to attenuate the intensity of inflammation and impact risk for acute cardiovascular events.

Molecular Pathways Regulating Macrovascular Pathology and Vascular Smooth Muscle Cells Phenotype in Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is a disease reaching a pandemic proportion in developed countries and a major risk factor for almost all cardiovascular diseases and their adverse clinical manifestations. T2DM leads to several macrovascular and microvascular alterations that influence the progression of cardiovascular diseases. Vascular smooth muscle cells (VSMCs) are fundamental players in macrovascular alterations of T2DM patients. VSMCs display phenotypic and functional alterations that reflect an altered intracellular biomolecular scenario of great vessels of T2DM patients. Hyperglycemia itself and through intraparietal accumulation of advanced glycation-end products (AGEs) activate different pathways, in particular nuclear factor-κB and MAPKs, while insulin and insulin growth-factor receptors (IGFR) are implicated in the activation of Akt and extracellular-signal-regulated kinases (ERK) 1/2. Nuclear factor-κB is also responsible of increased susceptibility of VSMCs to pro-apoptotic stimuli. Down-regulation of insulin growth-factor 1 receptors (IGFR-1R) activity in diabetic vessels also influences negatively miR-133a levels, so increasing apoptotic susceptibility of VSMCs. Alterations of those bimolecular pathways and related genes associate to the prevalence of a synthetic phenotype of VSMCs induces extracellular matrix alterations of great vessels. A better knowledge of those biomolecular pathways and related genes in VSMCs will help to understand the mechanisms leading to macrovascular alterations in T2DM patients and to suggest new targeted therapies.

Carotid Intima Media Thickness Is Independently Associated with Male Gender, Middle Age, and IGF-1 in Metabolically Healthy Obese Individuals

Background/Aims. The effect of benign obesity on subclinical cardiovascular disease is still questionable. The purpose of this study was to assess carotid intima media thickness (CIMT), as a marker of subclinical atherosclerosis, and to evaluate its relation to age, sex, and IGF-1 in metabolically healthy obese (MHO) subjects. Methods. A total of 75 MHO subjects and 80 age, and sex matched healthy nonobese control subjects were included in the study. Body mass index (BMI), waist circumference (WC), blood pressure, fasting plasma glucose, fasting insulin, HOMA-IR, lipid profile, insulin like growth factor-1 (IGF-1), and CIMT were assessed in all subjects. Results. MHO subjects had significantly higher CIMT and lower IGF-1 than healthy nonobese controls. Mean CIMT was significantly higher in MHO men age subgroup range from 30 to 50 years than in their age range matched (premenopausal) MHO women subgroup. In MHO subjects, CIMT was positively correlated with age, BMI, WC, SBP, HOMA-IR, TG, and LDL-C, and negatively correlated with IGF-1. Regression analysis revealed that middle age, male sex and IGF-1 remained independently associated with CIMT in MHO subjects. Conclusion. CIMT is elevated and IGF-1 is reduced in MHO subjects, and CIMT is independently associated with male gender, middle age, and IGF-1. Definition of healthy obesity may be broadened to include IMT measurement.

Aging, smooth muscle cells and vascular pathobiology: Implications for atherosclerosis

Epidemiological and autopsy studies suggest a close link between aging and the clinical manifestation of atherosclerosis. Several experiments show increased arterial susceptibility to atherogenetic stimuli in aged subjects. All together, these findings support the concept that aging represents an independent atherogenetic risk factor, intimately associated to other parietal, microenvironmental and systemic noxae. Smooth muscle cells (SMCs) represent the major arterial cell population. As aging occurs, SMCs progressively migrate from the tunica media and accumulate into the tunica intima. Myointimal thickening may represent the site where low-grade atherogenic stimuli cause early development and more severe lesion progression. Intimal SMC accumulation is characterized from a switch, from a differentiated to a synthetic phenotype, with reduced myocytic cytoskeletal markers and the expression of new proteins. Aging also associates to changes of SMC proliferative and apoptotic behavior and response to growth factors, such as transforming growth factor-beta1. The alteration of SMC properties represents a crucial event in the pathobiology of arterial wall, since it contributes to the vascular remodeling and decline of function with aging and favors the progression of atherosclerosis. Increased knowledge of biomolecular mechanisms regulating these events helps to develop new strategies aimed at contrasting the adverse effect of vascular aging.

Association between glycated hemoglobin and diet and other lifestyle factors in a nondiabetic population: cross-sectional evaluation of data from the Potsdam cohort of the European Prospective Investigation into Cancer and Nutrition Study

BACKGROUND

Glycation reactions of proteins and other compounds, depending on blood glucose concentrations, have a detrimental effect on health.

OBJECTIVE

The association of diet and other lifestyle factors with glycated hemoglobin (Hb A(1c)) values was examined in a nondiabetic population.

DESIGN

This was a cross-sectional study of 1773 middle-aged men and women. Mean Hb A(1c) values were calculated for categories of diet and lifestyle factors, and odds ratios (ORs) for the highest versus lowest tertiles of Hb A(1c) were determined and compared.

RESULTS

The OR of being in the highest Hb A(1c) tertile compared with the lowest increased with greater age [age 40-44 y compared with >60 y: men (OR: 2.86; 95% CI: 1.60, 5.20) and women: (6.11; 3.15, 12.30)] and greater obesity [body mass index (in kg/m(2)) >25 and waist-hip ratio >1.0 in men and >0.8 in women): men (2.80; 1.48, 5.45) and women (1.73; 1.15, 2.61)]. High energy and energy-adjusted saturated fat intakes were associated with increased risk of being in the highest tertile of Hb A(1c) [highest compared with lowest quintile: (1.53; 1.04, 2.26; P for trend = 0.013) and (1. 98; 1.33, 2.95; P for trend = 0.003), respectively]. No significant associations were observed for intakes of carbohydrates, protein, dietary fiber, or beta-carotene; however, some of the associations were nearly significant. Alcohol, vitamin C, and vitamin E intakes were inversely related to risk [highest compared with lowest quintile: (0.56; 0.38, 0.83; P for trend = 0.001), (0.50; 0.33, 0. 74; P for trend = 0.003), and (0.65; 0.43, 0.96; P for trend = 0. 036), respectively].

CONCLUSION

Hb A(1c) values might be modifiable by diet and other lifestyle factors.

Aging influences development and progression of early aortic atherosclerotic lesions in cholesterol-fed rabbits

The arterial wall in aged animals shows an increased susceptibility to develop atherosclerotic lesions, although the mechanisms by which aging acts are still unclear. We investigated early aortic lesions in aged rabbits (5 to 6 years old, AH group) and young rabbits (2 months old, YH group) after 2 months of 0.2% cholesterol feeding. Fatty streaks or spots mainly in the proximal segments occupied a relative surface area that was greater in AH than in YH rabbits, although plasma cholesterol and lipoprotein levels did not differ. YH lesions showed an irregular endothelial profile mainly from accumulations of large, rounded, RAM 11-positive macrophagic foam cells. There was a higher percentage of myocytic, CD-5-positive, proliferating, and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive cells and larger accumulation of glycosaminoglycans in AH fatty streaks than in YH lesions. Ligation-mediated polymerase chain reaction confirmed differences in apoptosis. Early fibromuscular coats and subendothelial plasma-like insudate were also observed in AH lesions. Aged-matched normocholesterolemic rabbits showed a diffuse aortic intimal thickening composed of myocytic cells with a synthetic phenotype and extracellular matrix rich in glycosaminoglycans. In addition, in aged rabbits, we observed a spontaneous increase of monocytes adhering to the endothelial surface and a reduced expression of endothelial nitric oxide synthase in areas distant from the branches. These plasma cholesterol-independent spontaneous changes in the aortic wall of aged rabbits seem to act as a multiple atherogenic risk factor. Moreover, age-related differences in the distribution, composition, and proliferative and apoptotic rates represent crucial events during the progression of early fatty streaks to advanced plaques.