Role of Phagocytosis in the Pro-Inflammatory Response in LDL-Induced Foam Cell Formation; a Transcriptome Analysis

CircZNF609 sponges miR-135b to up-regulate SEMA3A expression to alleviate ox-LDL-induced atherosclerosis

The initiation and progression of atherosclerotic plaque caused by abnormal lipid metabolism is one of the main causes of atherosclerosis (AS). Lipid droplet accumulation has become a novel research pointcut for AS treatment in recent years. In AS patients, miR-135b level was up-regulated relative to the normal cases, which showed negative correlations with the levels of Semaphorin 3A (SEMA3A) and circZNF609, separately. The U937-derived macrophages were cultured with ox-LDL to establish AS models in vitro. After that, the lipid accumulation, inflammation, mitochondrial dysfunction and cell death were evaluated by ORO, ELISA, RT-qPCR, western blot, JC-1 and FCM assays respectively. Transfection of the circZNF609 expression vector notably declined lipid accumulation, attenuated inflammation, reduced mitochondrial dysfunction and inhibited cell death in ox-LDL-stimulated cells. The direct binding of miR-135b to circZNF609 in vitro was confirmed using RIP assay, and SEMA3A expression was up-regulated by circZNF609 overexpression. After manipulating the endogenous expressions of circZNF609, miR-135b and SEMA3A, the above damages in ox-LDL-stimulated cells were rescued by inhibition of miR-135b expression and overexpression of circZNF609 or SEMA3A. Besides, the AS mice model was built to demonstrate the excessive lipid accumulation, increasing inflammation and cell death in AS pathogenesis according to the results of HE staining, ELISA and IHC assays, while these damages were reversed after overexpression of circZNF609 or SEMA3A. In AS models, overexpressed circZNF609 prevents the AS progression through depleting miR-135b expression and subsequent up-regulation of SEMA3A expression to overwhelm lipid accumulation, mitochondrial dysfunction and cell death.

Mitochondrial Genome Editing: Exploring the Possible Relationship of the Atherosclerosis-Associated Mutation m.15059G>A With Defective Mitophagy

Objective

The aim of this study was to evaluate the effect of the m.15059G>A mitochondrial nonsense mutation on cellular functions related to atherosclerosis, such as lipidosis, pro-inflammatory response, and mitophagy. Heteroplasmic mutations have been proposed as a potential cause of mitochondrial dysfunction, potentially disrupting the innate immune response and contributing to the chronic inflammation associated with atherosclerosis.

Methods

The human monocytic cell line THP-1 and cytoplasmic hybrid cell line TC-HSMAM1 were used. An original approach based on the CRISPR/Cas9 system was developed and used to eliminate mitochondrial DNA (mtDNA) copies carrying the m.15059G>A mutation in the MT-CYB gene. The expression levels of genes encoding enzymes related to cholesterol metabolism were analyzed using quantitative polymerase chain reaction. Pro-inflammatory cytokine secretion was assessed using enzyme-linked immunosorbent assays. Mitophagy in cells was detected using confocal microscopy.

Results

In contrast to intact TC-HSMAM1 cybrids, Cas9-TC-HSMAM1 cells exhibited a decrease in fatty acid synthase (FASN) gene expression following incubation with atherogenic low-density lipoprotein. TC-HSMAM1 cybrids were found to have defective mitophagy and an inability to downregulate the production of pro-inflammatory cytokines (to establish immune tolerance) upon repeated lipopolysaccharide stimulation. Removal of mtDNA harboring the m.15059G>A mutation resulted in the re-establishment of immune tolerance and the activation of mitophagy in the cells under investigation.

Conclusion

The m.15059G>A mutation was found to be associated with defective mitophagy, immune tolerance, and impaired metabolism of intracellular lipids due to upregulation of FASN in monocytes and macrophages.

The mediation effect of HDL-C: Non-HDL-C on the association between inflammatory score and recurrent coronary events

Background

Inflammation and lipids are both involved in the pathogenesis of coronary heart disease (CHD). However, the mediation effect of lipoproteins on the association between inflammation and recurrent coronary events in CHD patients remains unclear.

Methods

This was a retrospective study including CHD patients hospitalized in the Department of Cardiovascular Medicine in Sun Yat-sen Memorial Hospital between January 2011 and December 2012 with the endpoint of recurrent coronary events. The study calculated inflammatory score based on six serum inflammatory markers, including complement C3, complement C4, hyper-sensitive CRP, fibrinogen, D-dimer, and white blood cell count. Logistic regression analysis, subgroup analysis and mediation analysis were performed to assess the associations between inflammatory score and recurrent coronary events in different subpopulations and the identification of mediators. Inflammatory cytokine expression, cholesterol efflux capacity, and hepatic cholesterol influx were performed in additional CHD patients and healthy controls.

Results

There were 191 CHD patients included in the analysis with a median inflammatory score of -0.78 (-2.17, 1.35) and 63 cases of recurrent coronary events. Subgroup logistic regression analysis demonstrated that inflammatory score was positively associated with recurrent coronary events only in the diabetic subgroup [OR: 1.241 (1.004, 1.534), P < 0.046]. HDL-cholesterol (HDL-C): non-HDL-C performed 46.74 % of negative mediation effect on this association. CHD patients had lower cholesterol efflux capacity than healthy controls, which was mediated by HDL: non-HDL ratio of 0.4. No difference was found in hepatic cholesterol influx between the two groups.

Conclusion

Inflammatory score was associated with recurrent coronary events mediated by HDL-C: non-HDL-C ratio in diabetic CHD patients, indicating that lipoproteins might aggravate the inflammatory effect on atherosclerosis under hyperglycemia. Our findings suggested that anti-inflammatory and lipid-lowering therapies might be beneficial for this population.

Scavenger receptor-AI targeted theranostic nanoparticles for regression of atherosclerotic plaques via ABCA1 modulation

ATP-binding cassette transporter A1 (ABCA1) plays a crucial role in atherosclerotic formation through mediated cholesterol efflux in macrophage-derived foam cells. In this study, a scavenger receptors AI (SR-AI) targeted theranostic nanoparticles was constructed for atherosclerosis regression via ABCA1 activation in foam cells. ABCA1-upregulator 5242331 and IR780 were encapsulated in PLGA-PEG micelles which were conjugated with SR-AI targeting peptide (PP1) to formulate the nanoparticles (SAU-NPs). Immunostaining revealed that SR-AI was highly expressed both in macrophage foam cells and in atherosclerotic plaque of ApoE^-/- mice. The SAU-NPs have shown more active targeting to plaque lesion with higher stability compared with non-SR-AI targeted nanoparticles. The transformation from macrophage to foam cells was inhibited by SAU-NPs carried 5242331. Cholesterol deposition was effectively reduced in foam cells by SAU-NPs through activating the LXRα-ABCA1/ABCG1/SR-BI pathway. In conclusion, theranostic SAU-NPs which carried ABCA1-upregulator 5242331 exert beneficial effects on atherosclerosis regression via LXRα activation.

Discovery of drug-omics associations in type 2 diabetes with generative deep-learning models

The application of multiple omics technologies in biomedical cohorts has the potential to reveal patient-level disease characteristics and individualized response to treatment. However, the scale and heterogeneous nature of multi-modal data makes integration and inference a non-trivial task. We developed a deep-learning-based framework, multi-omics variational autoencoders (MOVE), to integrate such data and applied it to a cohort of 789 people with newly diagnosed type 2 diabetes with deep multi-omics phenotyping from the DIRECT consortium. Using in silico perturbations, we identified drug-omics associations across the multi-modal datasets for the 20 most prevalent drugs given to people with type 2 diabetes with substantially higher sensitivity than univariate statistical tests. From these, we among others, identified novel associations between metformin and the gut microbiota as well as opposite molecular responses for the two statins, simvastatin and atorvastatin. We used the associations to quantify drug-drug similarities, assess the degree of polypharmacy and conclude that drug effects are distributed across the multi-omics modalities.

Hypotheses on Atherogenesis Triggering: Does the Infectious Nature of Atherosclerosis Development Have a Substruction?

Since the end of the 20th century, it has been clear that atherosclerosis is an inflammatory disease. However, the main triggering mechanism of the inflammatory process in the vascular walls is still unclear. To date, many different hypotheses have been put forward to explain the causes of atherogenesis, and all of them are supported by strong evidence. Among the main causes of atherosclerosis, which underlies these hypotheses, the following can be mentioned: lipoprotein modification, oxidative transformation, shear stress, endothelial dysfunction, free radicals' action, homocysteinemia, diabetes mellitus, and decreased nitric oxide level. One of the latest hypotheses concerns the infectious nature of atherogenesis. The currently available data indicate that pathogen-associated molecular patterns from bacteria or viruses may be an etiological factor in atherosclerosis. This paper is devoted to the analysis of existing hypotheses for atherogenesis triggering, and special attention is paid to the contribution of bacterial and viral infections to the pathogenesis of atherosclerosis and cardiovascular disease.

Overexpressed PKM2 promotes macrophage phagocytosis and atherosclerosis

BACKGROUND

The expression of pyruvate kinase muscle 2 (PKM2) is augmented in macrophages of patients with atherosclerotic coronary artery disease. The role of PKM2 in atherosclerosis is to be determined.

METHODS

Global and myeloid cell-specific PKM2 knock-in mice with ApoE^-/- background (ApoE^-/- , PKM2^KI/KI and Lyz2-cre, ApoE^-/- , and PKM2^flox/flox ) were produced to evaluate the clinical significance of PKM2 in atherosclerosis development. Wild-type and PKM2 knock-in macrophages were isolated to assess the function of PKM2 in macrophage phagocytosis. Atherosclerotic mice were treated with PKM2 inhibitor shikonin (SKN) to evaluate the therapeutic potential of PKM2 suppression in atherosclerosis.

RESULTS

Oxidized low-density lipoprotein (oxLDL) upregulated PKM2 in macrophages. PKM2 in return promoted the uptake of oxLDL by macrophages. Overexpressed PKM2 accelerated atherosclerosis in mice. SKN blocked the progress of mouse atherosclerosis.

CONCLUSIONS

PKM2 accelerates macrophage phagocytosis and atherosclerosis. Targeting PKM2 is a potential therapy for atherosclerosis.

Transcriptome analysis reveals intrinsic pro-inflammatory signaling in healthy African American skin

Differences in morphology and physiology of darkly pigmented compared to lightly pigmented skin are well recognized. There are also disparities in prevalence and clinical features for many inflammatory skin diseases including atopic dermatitis and psoriasis; however, the underlying mechanisms are largely unknown. We compared the baseline gene expression in full thickness skin biopsies from healthy individuals self-reporting as African American (AA) or White Non-Hispanic (WNH). Extensively validated RNA-Seq analysis identified 570 differentially expressed genes (DEG) in AA skin including immunoglobulins and their receptors such as FCER1G; pro-inflammatory genes such as TNFα, IL-32; EDC (epidermal differentiation cluster) and keratin genes. DEGs were functionally enriched for inflammatory responses, keratinization, cornified envelope formation. RNA-seq analysis of 3D human skin equivalents (HSE) made from AA and WNH primary keratinocytes revealed 360 DEGs (some shared with skin) which were enriched by similar functions. AA HSE appeared more responsive to TNFα pro-inflammatory effects. Finally, AA-specific DEGs in skin and HSE significantly overlapped with molecular signatures of skin in AD and psoriasis patients. Overall, these findings suggest the existence of intrinsic pro-inflammatory circuits in AA keratinocytes/skin that may account for disease disparities and will help to build a foundation for the development of targeted skin disease prevention.

Danlou Tablets Inhibit Atherosclerosis in Apolipoprotein E-Deficient Mice by Inducing Macrophage Autophagy: The Role of the PI3K-Akt-mTOR Pathway

Atherosclerosis (AS) is a type of chronic vascular disease, and its etiology is not yet fully understood. AS is characterized by lipid deposition, atherosclerotic plaque formation, vascular stenosis or even complete blockage of the blood vessel wall. Clinical studies have shown that Danlou tablets (DLTs) can improve the heart function, quality of life, and prognosis of patients with coronary heart disease and myocardial infarction. However, its mechanism of action remains unknown. Our study revealed that DLTs ameliorated ApoE^−/−AS mouse aortic atherosclerotic plaques [hematoxylin-eosin (HE) staining and small animal ultrasound] and reduced CD68⁺ macrophage infiltration, the expression of the inflammatory factor interferon-gamma (IFN-γ), vascular smooth muscle α-actin, and serum lipid levels. In vitro, in the macrophage foaming model, DLTs partially restored the activity of RAW264.7 cells, reduced the uptake of lipid droplets, and inhibited lipid droplet accumulation and apoptosis within BMDMs. We also found that Torin1, an autophagy agonist, reduced intracellular lipid deposition in BMDMs, as did DLTs. Moreover, DLTs upregulated the expression of the autophagy-related protein LC3II and decreased p62 accumulation in RAW264.7 cells. DLTs also inhibited the phosphorylation of p-PI3K, p-Akt, and p-mTOR, leading to upregulated autophagy in RAW264.7 cells. In summary, our results suggested that DLTs can promote autophagy in macrophages by inhibiting the PI3K/Akt/mTOR signaling pathway, thereby reducing foam cell formation and improving atherosclerosis.

Role of Lipid Accumulation and Inflammation in Atherosclerosis: Focus on Molecular and Cellular Mechanisms

Atherosclerosis is a chronic lipid-driven and maladaptive inflammatory disease of arterial intima. It is characterized by the dysfunction of lipid homeostasis and signaling pathways that control the inflammation. This article reviews the role of inflammation and lipid accumulation, especially low-density lipoprotein (LDL), in the pathogenesis of atherosclerosis, with more emphasis on cellular mechanisms. Furthermore, this review will briefly highlight the role of medicinal plants, long non-coding RNA (lncRNA), and microRNAs in the pathophysiology, treatment, and prevention of atherosclerosis. Lipid homeostasis at various levels, including receptor-mediated uptake, synthesis, storage, metabolism, efflux, and its impairments are important for the development of atherosclerosis. The major source of cholesterol and lipid accumulation in the arterial wall is proatherogenic modified low-density lipoprotein (mLDL). Modified lipoproteins, such as oxidized low-density lipoprotein (ox-LDL) and LDL binding with proteoglycans of the extracellular matrix in the intima of blood vessels, cause aggregation of lipoprotein particles, endothelial damage, leukocyte recruitment, foam cell formation, and inflammation. Inflammation is the key contributor to atherosclerosis and participates in all phases of atherosclerosis. Also, several studies have shown that microRNAs and lncRNAs have appeared as key regulators of several physiological and pathophysiological processes in atherosclerosis, including regulation of HDL biogenesis, cholesterol efflux, lipid metabolism, regulating of smooth muscle proliferation, and controlling of inflammation. Thus, both lipid homeostasis and the inflammatory immune response are closely linked, and their cellular and molecular pathways interact with each other.

Recognition of Oxidized Lipids by Macrophages and Its Role in Atherosclerosis Development

Atherosclerosis is a multifactorial chronic disease that has a prominent inflammatory component. Currently, atherosclerosis is regarded as an active autoimmune process that involves both innate and adaptive immune pathways. One of the drivers of this process is the presence of modified low-density lipoprotein (LDL). For instance, lipoprotein oxidation leads to the formation of oxidation-specific epitopes (OSE) that can be recognized by the immune cells. Macrophage response to OSEs is recognized as a key trigger for initiation and a stimulator of progression of the inflammatory process in the arteries. At the same time, the role of oxidized LDL components is not limited to pro-inflammatory stimulation, but includes immunoregulatory effects that can have protective functions. It is, therefore, important to better understand the complexity of oxidized LDL effects in atherosclerosis in order to develop new therapeutic approaches to correct the inflammatory and metabolic imbalance associated with this disorder. In this review, we discuss the process of oxidized LDL formation, mechanisms of OSE recognition by macrophages and the role of these processes in atherosclerosis.

Prospects for the Use of Sialidase Inhibitors in Anti-atherosclerotic Therapy

The most typical feature of atherogenesis in humans at its early stage is the formation of foam cells in subendothelial arterial intima, which occurs as the consequence of intracellular cholesterol deposition. The main source of lipids accumulating in the arterial wall is circulating low-density lipoprotein (LDL). However, LDL particles should undergo proatherogenic modification to acquire atherogenic properties. One of the known types of atherogenic modification of LDL is enzymatic deglycosilation, namely, desialylation, which is the earliest change in the cascade of following multiple LDL modifications. The accumulating data make sialidases an intriguing and plausible therapeutic target, since pharmacological modulation of activity of these enzymes may have beneficial effects in several pathologies, including atherosclerosis. The hypothesis exists that decreasing LDL enzymatic desialylation may result in the prevention of lipid accumulation in arterial wall, thus breaking down one of the key players in atherogenesis at the cellular level. Several drugs acting as glycomimetics and inhibiting sialidase enzymatic activity already exist, but the concept of sialidase inhibition as an anti-atherosclerosis strategy remains unexplored to date. This review is focused on the potential possibilities of the repurposing of sialidase inhibitors for pathogenetic anti-atherosclerotic therapy.

Overview of OxLDL and Its Impact on Cardiovascular Health: Focus on Atherosclerosis

Cardiovascular pathologies maintain the leading position in mortality worldwide. Atherosclerosis is a chronic disease that can result in a variety of serious complications, such as myocardial infarction, stroke, and cardiovascular disease. Inflammation and lipid metabolism alterations play a crucial role in atherogenesis, but the details of relationships and causality of these fundamental processes remain not clear. The oxidation of LDL was considered the main atherogenic modification of LDL within the vascular wall for decades. However, recent investigations provided a growing body of evidence in support of the multiple LDL modification theory. It suggests that LDL particles undergo numerous modifications that change their size, density, and chemical properties within the blood flow and vascular wall. Oxidation is the last stage in this cascade resulting in the atherogenic properties. Moreover, recent investigations have discovered that oxLDL may have both anti-inflammatory and pro-inflammatory properties. Oxidized LDL can trigger inflammation through the activation of macrophages and other cells. After all, oxidized LDL is still a promising object for further investigations that have the potential to clarify the unknown parts of the atherogenic process. In this review, we discuss the role of oxLDL in atherosclerosis development on different levels.

Lipid Metabolism in Macrophages: Focus on Atherosclerosis

Mechanisms of lipid homeostasis and its impairment are of crucial importance for atherogenesis, and their understanding is necessary for successful development of new therapeutic approaches. In the arterial wall, macrophages play a prominent role in intracellular lipid accumulation, giving rise to foam cells that populate growing atherosclerotic plaques. Under normal conditions, macrophages are able to process substantial amounts of lipids and cholesterol without critical overload of the catabolic processes. However, in atherosclerosis, these pathways become inefficient, leading to imbalance in cholesterol and lipid metabolism and disruption of cellular functions. In this review, we summarize the existing knowledge on the involvement of macrophage lipid metabolism in atherosclerosis development, including both the results of recent studies and classical concepts, and provide a detailed description of these processes from the moment of lipid uptake with lipoproteins to cholesterol efflux.

Cellular Mechanisms of Human Atherogenesis: Focus on Chronification of Inflammation and Mitochondrial Mutations

Atherosclerosis is one of the most common diseases of the cardiovascular system that leads to the development of life-threatening conditions, such as heart attack and stroke. Arthrosclerosis affects various arteries in the human body, but is especially dangerous in the arteries alimenting heart and brain, aorta, and arteries of the lower limbs. By its pathophysiology, atherosclerosis is an inflammatory disease. During the pathological process, lesions of arterial intima in the form of focal thickening are observed, which form atherosclerotic plaques as the disease progresses further. Given the significance of atherosclerosis for the global health, the search for novel effective therapies is highly prioritized. However, despite the constant progress, our understanding of the mechanisms of atherogenesis is still incomplete. One of the remaining puzzles in atherosclerosis development is the focal distribution of atherosclerotic lesions in the arterial wall. It implies the existence of certain mosaicism within the tissue, with some areas more susceptible to disease development than others, which may prove to be important for novel therapy development. There are many hypotheses explaining this phenomenon, for example, the influence of viruses, and the spread in the endothelium of the vessel multinucleated giant endothelial cells. We suggest the local variations of the mitochondrial genome as a possible explanation of this mosaicism. In this review, we discuss the role of genetic variations in the nuclear and mitochondrial genomes that influence the development of atherosclerosis. Changes in the mitochondrial and nuclear genome have been identified as independent factors for the development of the disease, as well as potential diagnostic markers.

Signaling Pathways and Key Genes Involved in Regulation of foam Cell Formation in Atherosclerosis

Atherosclerosis is associated with acute cardiovascular conditions, such as ischemic heart disease, myocardial infarction, and stroke, and is the leading cause of morbidity and mortality worldwide. Our understanding of atherosclerosis and the processes triggering its initiation is constantly improving, and, during the last few decades, many pathological processes related to this disease have been investigated in detail. For example, atherosclerosis has been considered to be a chronic inflammation triggered by the injury of the arterial wall. However, recent works showed that atherogenesis is a more complex process involving not only the immune system, but also resident cells of the vessel wall, genetic factors, altered hemodynamics, and changes in lipid metabolism. In this review, we focus on foam cells that are crucial for atherosclerosis lesion formation. It has been demonstrated that the formation of foam cells is induced by modified low-density lipoprotein (LDL). The beneficial effects of the majority of therapeutic strategies with generalized action, such as the use of anti-inflammatory drugs or antioxidants, were not confirmed by clinical studies. However, the experimental therapies targeting certain stages of atherosclerosis, among which are lipid accumulation, were shown to be more effective. This emphasizes the relevance of future detailed investigation of atherogenesis and the importance of new therapies development.