Glycosylation of blood cells during the onset and progression of atherosclerosis and myocardial infarction

Protein glycosylation controls cell-cell and cell-extracellular matrix (ECM) communication in immune, vascular, and inflammatory processes, underlining the critical role of this process in the identification of disease biomarkers and the design of novel therapies. Emerging evidence highlights the critical role of blood cell glycosylation in the pathophysiology of atherosclerosis (ATH) and myocardial infarction (MI). Here, we review the role of glycosylation in the interplay between blood cells, particularly erythrocytes, and endothelial cells (ECs), highlighting the involvement of this critical post/cotranslational modification in settings of cardiovascular disease (CVD). Importantly, we focus on emerging preclinical studies and clinical trials based on glycan-targeted drugs to validate their therapeutic potential. These findings may help establish new trends in preventive medicine and delineate novel targeted therapies in CVD.

The Role of Blood Viscosity in Infectious Diseases

Blood viscosity is increased by elevated concentrations of acute phase reactants and hypergammaglobulinemia in inflammation. These increase blood viscosity by increasing plasma viscosity and fostering erythrocyte aggregation. Blood viscosity is also increased by decreased erythrocyte deformability, as occurs in malaria. Increased blood viscosity contributes to the association of acute infections with myocardial infarction (MI), venous thrombosis, and venous thromboembolism. It also increases vascular resistance, which decreases tissue perfusion and activates stretch receptors in the left ventricle, thereby initiating the systemic vascular resistance response. This compensates for the increased vascular resistance by vasodilation, lowering hematocrit, and decreasing intravascular volume. This physiological response causes the anemias associated with malaria, chronic inflammation, and other chronic diseases. Since tissue perfusion is inversely proportional to blood viscosity, anemia may be beneficial as it increases tissue perfusion when erythrocyte aggregating factors or erythrocytes with decreased deformability are present in the blood.

Plasma Aldosterone Levels Are Not Associated With Cardiovascular Events Among Patients With High-Risk Vascular Disease: Insights From the ACCELERATE Trial

Background

The failure of cholesteryl ester transfer protein inhibitor torcetrapib was associated with an off‐target increase in plasma aldosterone. We sought to evaluate the impact of evacetrapib on plasma aldosterone level and determine the association between plasma aldosterone level and major adverse cardiovascular events among patients with stable high‐risk vascular disease enrolled in the ACCELERATE (Assessment of Clinical Effects of Cholesteryl Ester Transfer Protein Inhibition With Evacetrapib in Patients at a High Risk for Vascular Outcomes) trial.

Methods and Results

We included all patients with a plasma aldosterone level (N=1624) and determined the impact of evacetrapib exposure compared with placebo on plasma aldosterone levels after 12 months of treatment. Using baseline and postexposure aldosterone levels, hazard ratios for major adverse cardiovascular events (cardiovascular death, nonfatal myocardial infarction, cerebrovascular accident, hospitalization for unstable angina, and revascularization) with increasing quartile of baseline and percentage change in plasma aldosterone level at follow‐up were calculated. The average age was 65.2 years, 75.7% were men, 93.7% were hypertensive, 73.3% were diabetic, and 57.6% had a prior myocardial infarction. Baseline plasma aldosterone level (85.2 [43, 150] versus 86.8 [43, 155] pmol/L; P=0.81) and follow‐up percentage change (13.6% [−29, 88] versus 17.9% [−24, 87]; P=0.23) were similar between those who received evacetrapib and placebo. During median follow‐up of 28 months, major adverse cardiovascular events occurred in 263 patients (16.2%). The hazard ratios for increasing quartile of baseline or percentage change in plasma aldosterone level at follow‐up were not significant for major adverse cardiovascular events. These findings remained consistent when adjusting for significant characteristics.

Conclusions

Exposure to evacetrapib did not result in significant change in plasma aldosterone levels compared with placebo. Among patients with stable high‐risk vascular disease, plasma aldosterone levels were not a predictor for future cardiovascular events.

Clinical Trial Registration

URL: http://www.ClinicalTrials.gov. Unique identifier: NCT01687998.

Apolipoprotein(a) is the Product of a Pseudogene: Implications for the Pathophysiology of Lipoprotein(a)

Apolipoprotein(a) [apo(a)] is an apolipoprotein unique to lipoprotein(a) [Lp(a)]. Although it has no known function, Lp(a) is a risk factor for accelerated atherothrombosis. We hypothesize that LPA, the gene which encodes apo(a), is a heretofore unrecognized unprocessed pseudogene created by duplication of PLG, the gene which encodes plasminogen. Unprocessed pseudogenes are genes which were created by duplication of functional genes and subsequently lost function after acquiring various mutations. This hypothesis explains many of the unusual features of Lp(a) and apo(a). Also, this hypothesis has implications for the therapy of elevated Lp(a) and atherothrombosis theory. Because apo(a) is functionless, the diseases associated with elevated levels of Lp(a) are due to its impact on blood viscosity.

Flawed Reasoning Allows the Persistence of Mainstream Atherothrombosis Theory

Deaths due to atherothrombosis are increasing throughout the world except in the lowest socio-demographic stratum. This is despite 60 years of study and expenditure of billions of dollars on lipid theory. Nevertheless, mainstream atherothrombosis theory persists even though it has failed numerous tests. Contrary data are ignored, consistent with the practice of science as envisioned by Thomas Kuhn. This paper examines defects in mainstream atherogenesis theory and the flawed logic which allows its persistence in the face of what should be obvious shortcomings.