[LDL: from metabolic syndrome to instability of the atherosclerotic plaque]

Arterial Thickness and Immunometabolism: The Mediating role of Chronic Exercise

Metabolic alterations and cardiovascular diseases, such as atherosclerosis, are associated with lifestyle modifications, particularly the increase of physical inactivity and poor eating habits, which contribute to one of the main causes of death in modern times. Cardiovascular diseases are positively correlated with several illnesses, such as obesity, hypertension and dyslipidemia, and these disorders are known to contribute to changes in immune cells, cytokines and metabolism. Atherosclerosis is a chronic inflammatory disease characterized by the formation of lipid plaques and fibrous tissue (atheroma) in the artery walls and this process is related to the oxidation of LDL-c (low density lipoprotein) and the formation of a particle, termed LDLox, which can generate toxic injury to the vessel wall. In this atherogenic process there is an inflammatory response generated by the injury in the vascular endothelium, which in itself is able to express and secrete a variety of molecules, such as myeloid colony-stimulating factors (M-CSF), monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor alpha (TNF-α), that act as activators of the immune system. Therefore, the main purpose of this review is to highlight the immuno-metabolic alterations involving the thickening and stiffness of arteries observed in atherosclerosis, and how chronic exercise can act as an anti-inflammatory and anti-atherogenic approach.

Validation of the friedewald formula in patients with metabolic syndrome

Currently, the Friedewald formula (FF) is the main method for evaluating low-density lipoprotein cholesterol (LDL-c). Recently, many limitations have emerged regarding its use, including patients with triglyceride levels ≥400 mg/dL, diabetes mellitus, and kidney or hepatic chronic diseases. We analyzed the use of the FF in patients with metabolic syndrome. We selected patients with known metabolic syndrome that fulfilled the National Cholesterol Education Program Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) Final Report and excluded patients with triglyceride levels ≥400 mg/dL and chronic liver and/or kidney disease. Using direct assays, we measured total cholesterol, high-density lipoprotein cholesterol, triglycerides, and LDL-c. Then, LDL-c was estimated using the FF and compared with the LDL-c by direct assay. The sample size was 135 patients. Using the FF, the mean LDL-c value was 124.4 ± 42.1 mg/dL; it was 125.1 ± 38.5 mg/dL by direct assay. The correlation coefficient between these two methods was 0.89, with statistical significance (P  value < 0.001). There were no significant differences between the patients with triglyceride levels >150 mg/dL (P = 0.618). In conclusion, FF is a good method for estimating LDL-c in patients with metabolic syndrome.

The roles of genetic polymorphisms and human immunodeficiency virus infection in lipid metabolism

Dyslipidemia has been frequently observed among individuals infected with human immunodeficiency virus type 1 (HIV-1), and factors related to HIV-1, the host, and antiretroviral therapy (ART) are involved in this phenomenon. This study reviews the roles of genetic polymorphisms, HIV-1 infection, and highly active antiretroviral therapy (HAART) in lipid metabolism. Lipid abnormalities can vary according to the HAART regimen, such as those with protease inhibitors (PIs). However, genetic factors may also be involved in dyslipidemia because not all patients receiving the same HAART regimen and with comparable demographic, virological, and immunological characteristics develop variations in the lipid profile. Polymorphisms in a large number of genes are involved in the synthesis of structural proteins, and enzymes related to lipid metabolism account for variations in the lipid profile of each individual. As some genetic polymorphisms may cause dyslipidemia, these allele variants should be investigated in HIV-1-infected patients to identify individuals with an increased risk of developing dyslipidemia during treatment with HAART, particularly during therapy with PIs. This knowledge may guide individualized treatment decisions and lead to the development of new therapeutic targets for the treatment of dyslipidemia in these patients.

Effect of atorvastatin on atherosclerotic plaque formation and platelet activation in hypercholesterolemic rats

We aimed to investigate whether atorvastatin influenced the CD40-CD40L pathway in atherosclerosis formation in rats fed a high cholesterol diet. Thirty-six male Wistar rats were divided among 4 groups as follows: control (C), statin (S), 5% cholesterol fed (HC), and statin-administered hypercholesterolemic (HCS). Serum levels of lipids, soluble CD40L, platelet factor 4, and interleukin-6 were assayed with commercial kits. The number of platelets expressing surface P-selectin, CD40, and CD40L were determined by flow cytometry. Aortas were examined for fatty streaks. In the HC group, we observed a significant increase in serum lipid levels and platelet activation markers compared with the control group. Rats in the HCS group had a significant decrease in lipid levels and downregulation in the number of platelets expressing surface P-selectin, CD40, and CD40L compared with the HC group. We observed decreased fatty streak formations in aortas in HCS rats. A positive correlation was found for platelet activation markers and atherosclerotic fatty streak formations. Regression analysis revealed that the predictor of atherosclerosis was CD40L. Our study suggests that in a rat hypercholesterolemic model, statin treatment may influence the CD40-CD40L dyad, and that this effect is parallelled by a suppression of progression of atherosclerotic plaque formation.

HDL: o yin-yang da doença cardiovascular

Estudos epidemiológicos mostram relação inversa entre níveis plasmáticos de HDL-colesterol (HDL-C) e incidência de doença cardiovascular (DCV). O papel antiaterogênico da HDL é atribuído às suas atividades anti-inflamatória, antitrombótica e antioxidante, além de sua participação no transporte reverso de colesterol (TRC), processo pelo qual a HDL remove colesterol dos tecidos periféricos, incluindo macrófagos da íntima arterial, e o transporta para o fígado para ser excretado pela bile. Com base nesses fatos, o HDL-C tornou-se alvo atrativo para a prevenção da DCV. No entanto, o fracasso do torcetrapib, droga que aumenta substancialmente os níveis de HDL-C, em prevenir DCV, além do conhecimento gerado por estudos de modelos animais e doenças monogênicas que afetam a concentração de HDL-C, tem suscitado questionamentos sobre o papel antiaterogênico da HDL. Esta revisão tem como objetivo abordar aspectos atuais do conhecimento da HDL, baseando-se nessas recentes controvérsias.

Electronegative low-density lipoprotein is associated with dense low-density lipoprotein in subjects with different levels of cardiovascular risk

Dyslipidemias and physicochemical changes in low-density lipoprotein (LDL) are very important factors for the development of coronary artery disease (CAD). However, pathophysiological properties of electronegative low-density lipoprotein [LDL(-)] remain a controversial issue. Our objective was to investigate LDL(-) content in LDL and its subfractions (phenotypes A and B) of subjects with different cardiovascular risk. Seventy-three subjects were randomized into three groups: normolipidemic (N; n = 30) and hypercholesterolemic (HC; n = 33) subjects and patients with CAD (n = 10). After fasting, blood samples were collected and total, dense and light LDL were isolated. LDL(-) content in total LDL and its subfractions was determined by ELISA. LDL(-) content in total LDL was lower in the N group as compared to the HC (P < 0.001) and CAD (P = 0.006) groups. In the total sample and in those of the N, HC, and CAD groups, LDL(-) content in dense LDL was higher than in light LDL (P = 0.001, 0.001, 0.001, and 0.033, respectively) The impact of LDL(-) on cardiovascular risk was reinforced when LDL(-) content in LDL showed itself to have a positive association with total cholesterol (beta = 0.003; P < 0.001), LDL-C (beta = 0.003; p < 0.001), and non-HDL-C (beta = 0.003; P < 0.001) and a negative association with HDL-C (beta = -0.32; P = 0.04). Therefore, LDL(-) is an important biomarker that showed association with the lipid profile and the level of cardiovascular risk.

[Metformin effects upon blood pressure and glucose metabolism of monossodium glutamate induced-obese spontaneously hypertensive rats]

OBJECTIVES

To make available experimental model for the metabolic syndrome (MS) and verify effects of chronic oral treatment with metformin upon blood pressure (BP), body weight (BW), glucose metabolism, epididimal fat content (EF).

METHOD

Males SHR received monossodium glutamate (MSG, 2 mg/kg/day/sc) during first 11 days of life. Control animals received saline. After 12 weeks, animals were separated in two groups, treated either with metformin 500 mg/ kg/day or vehicle during 12 weeks. PA and BW were determined. At the end of the follow-up, animals underwent an oral glucose tolerance test (OGTT) and insulin sensitivity index was determined. Upon sacrifice EF was measured.

RESULTS

MSG worsened insulin resistance and induced visceral obesity in SHR, without change BP. Treatment with metformin improved glucose metabolism and reduces EF and BP.

CONCLUSIONS

These observations emphasize the role of hepatic insulin resistance on MS and point out for beneficial cardiovascular effects with improvement in the insulin sensitivity.

Vitaminas e minerais com propriedades antioxidantes e risco cardiometabólico: controvérsias e perspectivas

No processo celular de obtenção de energia, são gerados compostos chamados espécies reativas de oxigênio (ERO) que, em excesso, podem causar danos celulares. Estresse oxidativo resulta do desequilíbrio no estado de óxido-redução a favor da oxidação. Dos mecanismos de defesa antioxidante, participam enzimas endógenas e algumas vitaminas e minerais. A vitamina E encontra-se no plasma e na partícula de LDL, protegendo lipídeos da oxidação. Estudos observacionais relataram associação inversa entre ingestão de vitamina E e risco cardiometabólico (RCM). Entretanto, ensaios clínicos não comprovaram a eficácia de sua suplementação nos desfechos cardiometabólicos. A vitamina C participa do sistema de regeneração da vitamina E, mantendo o potencial antioxidante plasmático. Dados sobre os benefícios de sua suplementação na redução do risco cardiometabólico são inconclusivos. A atividade antioxidante dos carotenoides é responsável, em parte, por seu papel protetor contra doenças cardiovasculares e cânceres. A suplementação desse nutriente também não trouxe resultados consistentes no que se refere à redução do RCM. A participação do zinco e do selênio na defesa antioxidante vem sendo estudada mais recentemente, mas a sua suplementação em indivíduos com níveis séricos normais e ingestão adequada na dieta desses minerais não parece ser necessária. De um modo geral, há muita controvérsia sobre o papel desses micronutrientes no RCM. Estudos epidemiológicos sugerem que o consumo de substâncias antioxidantes provenientes da dieta ou dietas ricas em frutas e hortaliças diminui o RCM. Mais estudos são necessários antes de se recomendar o uso de antioxidantes isolados na forma de suplementos para tal finalidade.

[Cardiovascular disease in diabetes mellitus: classical and non-classical risk factors]

Cardiovascular disease, which includes coronary heart disease (CHD), cerebrovascular disease (CVD), and peripheral vascular disease (PVD), is the leading cause of mortality in populations, particularly in the diabetic one. Individuals with diabetes have at least a two-fold to four-fold increased risk of having cardiovascular events and a double risk of death compared with age-matched subjects without diabetes. A decline in mortality from CVD has been shown, but decline due to CHD is consistently lower in individuals with diabetes when compared with non-diabetics. The presence of several factors in diabetes leads to high occurrence of CVD such as hyperglycemia, insulin resistance, and classical and non-classical risk factors (systemic hypertension, dyslipidemia, obesity, proinflammatory condition and others). It is possible that the atherogenic role of obesity may be at least in part due to increased adipocyte production of cytokines. Considering the marked association of diabetes and CVD and unfavorable prognosis following an event, it is important to identify who is at high risk and how to screen. The American Heart Association and American Diabetes Association recommend risk stratification using diagnostic tests. However, the challenge is to accurately identify patients without a prior history of an event and those without symptoms strongly suggesting CVD, in whom additional testing would be indicated in order to achieve the most effective prevention. The benefits of glycemic control and the other risk factors have already been shown and justify optimization of the management of this high-risk population, aiming to reduce cardiovascular mortality disease and improve quality of life.