Oxysterols in heart failure

Oxysterols as Biomarkers of Aging and Disease

Oxysterols derive from either enzymatic or non-enzymatic oxidation of cholesterol. Even though they are produced as intermediates of bile acid synthesis pathway, they are recognised as bioactive compounds in cellular processes. Therefore, their absence or accumulation have been shown to be associated with disease phenotypes. This chapter discusses the contribution of oxysterol to ageing, age-related diseases such as neurodegeneration and various disorders such as cancer, cardiovascular disease, diabetes, metabolic and ocular disorders. It is clear that oxysterols play a significant role in development and progression of these diseases. As a result, oxysterols are being investigated as suitable markers for disease diagnosis purposes and some drug targets are in development targeting oxysterol pathways. However, further research will be needed to confirm the suitability of these potentials.

Lipid Peroxidation in Atherosclerotic Cardiovascular Diseases

Significance: Atherosclerotic cardiovascular diseases (ACVDs) continue to be a primary cause of mortality worldwide in adults aged 35-70 years, occurring more often in countries with lower economic development, and they constitute an ever-growing global burden that has a considerable socioeconomic impact on society. The ACVDs encompass diverse pathologies such as coronary artery disease and heart failure (HF), among others. Recent Advances: It is known that oxidative stress plays a relevant role in ACVDs and some of its effects are mediated by lipid oxidation. In particular, lipid peroxidation (LPO) is a process under which oxidants such as reactive oxygen species attack unsaturated lipids, generating a wide array of oxidation products. These molecules can interact with circulating lipoproteins, to diffuse inside the cell and even to cross biological membranes, modifying target nucleophilic sites within biomolecules such as DNA, lipids, and proteins, and resulting in a plethora of biological effects. Critical Issues: This review summarizes the evidence of the effect of LPO in the development and progression of atherosclerosis-based diseases, HF, and other cardiovascular diseases, highlighting the role of protein adduct formation. Moreover, potential therapeutic strategies targeted at lipoxidation in ACVDs are also discussed. Future Directions: The identification of valid biomarkers for the detection of lipoxidation products and adducts may provide insights into the improvement of the cardiovascular risk stratification of patients and the development of therapeutic strategies against the oxidative effects that can then be applied within a clinical setting.

High Cholesterol Diet-Induced Changes in Oxysterol and Scavenger Receptor Levels in Heart Tissue

Involvement of high cholesterol and oxidative stress in cardiovascular diseases is well studied, as it can be hypothesized that various products originated from lipid peroxidation, such as oxysterols, or affected protein expression might lead to cardiomyocyte damage followed by the pathological modifications. Although oxidation of excessive cholesterol to oxysterols in elevated stress conditions is identified by a number of studies, the role of a high cholesterol diet in regulating fatty acid and oxysterol accumulation, together with scavenger receptor mRNA levels, in the heart remains little investigated. Our study provides a detailed analysis of the changes in fatty acid, oxysterol, and scavenger receptor profiles and its relation with histological alterations in the heart tissue. We evaluated alterations of fatty acid composition, by the GC-MS method, while 4β-, 25-, and 27-hydroxycholesterol and 7-ketocholesterol levels by means of LC-MS/MS in high cholesterol diet-fed rabbits. Additionally, a number of proteins related to lipid metabolism and scavenger receptor mRNA expressions were evaluated by Western blotting and RT-PCR. According to our in vivo results, a high cholesterol diet enhances a number of unsaturated fatty acids, oxysterols, and LXRα, in addition to CD36, CD68, CD204, and SR-F1 expressions while α-tocopherol supplementation decreases LXRα and SR expressions together with an increase in 27-hydroxycholesterol and ABCA1 levels. Our results indicated that the high cholesterol diet modulates proteins related to lipid metabolism, which might result in the malfunction of the heart and α-tocopherol shows its beneficial effects. We believe that this work will lead the generation of different theories in the development of heart diseases.

Nanomedicine for the cardiac myocyte: Where are we?

Biomedical achievements in the last few decades, leading to successful therapeutic interventions, have considerably improved human life expectancy. Nevertheless, the increasing load and the still suboptimal outcome for patients with cardiac dysfunction underlines the relevance of continuous research to develop novel therapeutics for these diseases. In this context, the field of nanomedicine has attracted a lot of attention due to the potential novel treatment possibilities, such as controlled and sustained release, tissue targeting, and drug protection from degradation. For cardiac myocytes, which constitute the majority of the heart by mass and are the contractile unit, new options have been explored in terms of the use of nanomaterials (NMs) for therapy, diagnosis, and tissue engineering. This review focuses on the advances of nanomedicine targeted to the cardiac myocyte: first presenting the NMs used and the principal cardiac myocyte-based afflictions, followed by an overview of key advances in the field, including NMs interactions with the cardiac myocyte, therapy delivery, diagnosis based on imaging, and tissue engineering for tissue repair and heart-on-a-chip devices.

Iron nanoparticles increase 7-ketocholesterol-induced cell death, inflammation, and oxidation on murine cardiac HL1-NB cells

OBJECTIVE

To evaluate the cytotoxicity of iron nanoparticles on cardiac cells and to determine whether they can modulate the biological activity of 7-ketocholesterol (7KC) involved in the development of cardiovascular diseases. Nanoparticles of iron labeled with Texas Red are introduced in cultures of nonbeating mouse cardiac cells (HL1-NB) with or without 7-ketocholesterol 7KC, and their ability to induce cell death, pro-inflammatory and oxidative effects are analyzed simultaneously.

STUDY DESIGN

Flow cytometry (FCM), confocal laser scanning microscopy (CLSM), and subsequent factor analysis image processing (FAMIS) are used to characterize the action of iron nanoparticles and to define their cytotoxicity which is evaluated by enhanced permeability to SYTOX Green, and release of lactate deshydrogenase (LDH). Pro-inflammatory effects are estimated by ELISA in order to quantify IL-8 and MCP-1 secretions. Pro-oxidative effects are measured with hydroethydine (HE).

RESULTS

Iron Texas Red nanoparticles accumulate at the cytoplasmic membrane level. They induce a slight LDH release, and have no inflammatory or oxidative effects. However, they enhance the cytotoxic, pro-inflammatory and oxidative effects of 7KC. The accumulation dynamics of SYTOX Green in cells is measured by CLSM to characterize the toxicity of nanoparticles. The emission spectra of SYTOX Green and nanoparticles are differentiated, and corresponding factor images specify the possible capture and cellular localization of nanoparticles in cells.

CONCLUSION

The designed protocol makes it possible to show how Iron Texas Red nanoparticles are captured by cardiomyocytes. Interestingly, whereas these fluorescent iron nanoparticles have no cytotoxic, pro-inflammatory or oxidative activities, they enhance the side effects of 7KC.