Associations of ABCG1-mediated cholesterol efflux capacity with coronary artery lipid content assessed by near-infrared spectroscopy

ATP-binding cassette G1 membrane transporter-mediated cholesterol efflux capacity influences coronary atherosclerosis and cardiovascular risk in Rheumatoid Arthritis

OBJECTIVES

Cholesterol efflux capacity (CEC) measures the ability of high-density lipoprotein (HDL) to remove cholesterol from macrophages and reduce the lipid content of atherosclerotic plaques. CEC inversely associated with cardiovascular risk beyond HDL-cholesterol levels. CEC through the ATP-binding-cassette G1 (ABCG1) membrane transporter is impaired in rheumatoid arthritis (RA). We evaluated associations of ABCG1-CEC with coronary atherosclerosis, plaque progression and cardiovascular risk in RA.

METHODS

Coronary atherosclerosis (noncalcified, partially, fully-calcified, low-attenuation plaque) was assessed with computed tomography angiography in 140 patients and reevaluated in 99 after 6.9 ± 0.3 years. Cardiovascular events including acute coronary syndromes, stroke, cardiovascular death, claudication, revascularization and hospitalized heart failure were recorded. ABCG1-CEC was measured in Chinese hamster ovary cells as percentage of effluxed over total intracellular cholesterol.

RESULTS

ABCG1-CEC inversely associated with extensive atherosclerosis (≥5 plaques) (adjusted odds ratio 0.50 [95% CI 0.28-0.88]), numbers of partially-calcified (rate ratio [RR] 0.71 [0.53-0.94]) and low-attenuation plaques (RR 0.63 [0.43-0.91] per standard deviation increment). Higher ABCG1-CEC predicted fewer new partially-calcified plaques in patients with lower baseline and time-averaged CRP and fewer new noncalcified and calcified plaques in those receiving higher mean prednisone dose. ABCG1-CEC inversely associated with events in patients with but not without noncalcified plaques, with <median but not higher CRP and in prednisone users but not nonusers (p-for-interaction = 0.021, 0.033 and 0.008 respectively).

CONCLUSION

ABCG1-CEC inversely associated with plaque burden and vulnerability, and plaque progression conditionally on cumulative inflammation and corticosteroid dose. ABCG1-CEC inversely associated with events specifically in patients with noncalcified plaques, lower inflammation and in prednisone users.

Genomic Variants and Multilevel Regulation of ABCA1, ABCG1, and SCARB1 Expression in Atherogenesis

Atheroprotective properties of human plasma high-density lipoproteins (HDLs) are determined by their involvement in reverse cholesterol transport (RCT) from the macrophage to the liver. ABCA1, ABCG1, and SR-BI cholesterol transporters are involved in cholesterol efflux from macrophages to lipid-free ApoA-I and HDL as a first RCT step. Molecular determinants of RCT efficiency that may possess diagnostic and therapeutic meaning remain largely unknown. This review summarizes the progress in studying the genomic variants of ABCA1, ABCG1, and SCARB1, and the regulation of their function at transcriptional and post-transcriptional levels in atherosclerosis. Defects in the structure and function of ABCA1, ABCG1, and SR-BI are caused by changes in the gene sequence, such as single nucleotide polymorphism or various mutations. In the transcription initiation of transporter genes, in addition to transcription factors, long noncoding RNA (lncRNA), transcription activators, and repressors are also involved. Furthermore, transcription is substantially influenced by the methylation of gene promoter regions. Post-transcriptional regulation involves microRNAs and lncRNAs, including circular RNAs. The potential biomarkers and targets for atheroprotection, based on molecular mechanisms of expression regulation for three transporter genes, are also discussed in this review.

Applications of Artificial Intelligence (AI) for cardiology during COVID-19 pandemic

Background and aims

Artificial Intelligence (AI) shows extensive capabilities to impact different healthcare areas during the COVID-19 pandemic positively. This paper tries to assess the capabilities of AI in the field of cardiology during the COVID-19 pandemic. This technology is useful to provide advanced technology-based treatment in cardiology as it can help analyse and measure the functioning of the human heart.

Methods

We have studied a good number of research papers on Artificial Intelligence on cardiology during the COVID-19 pandemic to identify its significant benefits, applications, and future scope. AI uses artificial neuronal networks (ANN) to predict. In cardiology, it is used to predict the survival of a COVID-19 patient from heart failure.

Results

AI involves complex algorithms for predicting somewhat successful diagnosis and treatments. This technology uses different techniques, such as cognitive computing, deep learning, and machine learning. It is incorporated to make a decision and resolve complex challenges. It can focus on a large number of diseases, their causes, interactions, and prevention during the COVID-19 pandemic. This paper introduces AI-based care and studies its need in the field of cardiology. Finally, eleven major applications of AI in cardiology during the COVID-19 pandemic are identified and discussed.

Conclusions

Cardiovascular diseases are one of the major causes of death in human beings, and it is increasing for the last few years. Cardiology patients' treatment is expensive, so this technology is introduced to provide a new pathway and visualise cardiac anomalies. AI is used to identify novel drug therapies and improve the efficiency of a physician. It is precise to predict the outcome of the COVID-19 patient from cardiac-based algorithms. Artificial Intelligence is becoming a popular feature of various engineering and healthcare sectors, is thought for providing a sustainable treatment platform. During the COVID-19 pandemic, this technology digitally controls some processes of treatments.

Functional pasta consumption in healthy volunteers modulates ABCG1-mediated cholesterol efflux capacity of HDL

BACKGROUNDS AND AIMS

Prevention of cardiovascular (CV) disease is considered a central issue in public health and great attention is payed to nutritional approaches, including consumption of functional foods to reduce CV risk in individuals without indications for anti-atherosclerotic drugs. Cholesterol efflux capacity (CEC) is an important anti-atherogenic property of HDL and a marker of CV risk. We evaluated the effect of a daily consumption of an innovative whole-wheat synbiotic pasta, compared to a control whole-wheat pasta, on serum ATP binding cassette G1 (ABCG1)-mediated CEC in healthy overweight or obese individuals.

METHODS AND RESULTS

Study participants (n = 41) were randomly allocated to either innovative or control pasta, consumed daily for twelve weeks. Serum CEC was measured before and after the dietary intervention, by a well-established radioisotopic technique on Chinese Hamster Ovary Cells transfected with human ABCG1. The innovative synbiotic pasta consumption was associated to a significantly higher post treatment/baseline ratio of ABCG1-mediated CEC values with respect to control pasta (mean ratio 1.05 ± 0.037 and 0.95 ± 0.042 respectively, p < 0.05). Analysis of the relationship between ABCG1-mediated CEC and glycemia, homocysteine, total folates and interleukin-6 showed specific changes in the correlations between HDL function and glycemia, oxidative and inflammatory markers only after synbiotic pasta consumption.

CONCLUSION

This is the first report on serum CEC improvement obtained by a new synbiotic functional pasta consumption, in absence of lipid profile modifications, in overweight/obese participants. This pilot study suggests that a simple dietary intervention can be a promising approach to CV preservation through improving of athero-protective HDL function.

Sirt6 deficiency aggravates angiotensin II-induced cholesterol accumulation and injury in podocytes

Disturbed renal lipid metabolism, especially cholesterol dysregulation plays a crucial role in the pathogenesis of chronic kidney disease (CKD). We recently reported that angiotensin (Ang) II could induce cholesterol accumulation and injury in podocytes. However, the underlying mechanisms for these alterations remain unknown. Methods: Bioinformatics analysis of renal biopsy specimens from patients with hypertensive nephropathy (HN) suggests the involvement of Sirtuin 6 (Sirt6) in Ang II-induced dysregulation of glomerular cholesterol. Using a podocyte-specific Sirt6 knockout mouse model, the effects of Sirt6 on Ang II-induced cholesterol accumulation in podocytes and the therapeutic efficacies of cholesterol-lowering agents were evaluated. Results: Cholesterol accumulation was detected in the podocytes of Ang II-infused mice, whereas selective deletion of Sirt6 in podocytes not only increased cholesterol accumulation in these cells but also exacerbated Ang II-induced kidney injury. Deletion of Sirt6 also attenuated the protective effect of cyclodextrin (CD) on Ang II-induced urinary albumin excretion, glomerulosclerosis and podocyte injury. In addition, we demonstrated that Sirt6 affected cholesterol efflux in podocytes by regulating the expression of ATP-binding cassette transporter G1 (ABCG1). Conclusions: These findings provide evidence that Sirt6 is a potential target for renin-angiotensin system (RAS)-associated podocyte injury and provide a rationale for the application of cholesterol-lowering agents in patients with CKD.

CXCL12 promotes atherosclerosis by downregulating ABCA1 expression via the CXCR4/GSK3β/β-cateninT120/TCF21 pathway

CXC chemokine ligand 12 (CXCL12) is a member of the CXC chemokine family and mainly acts on cell chemotaxis. CXCL12 also elicits a proatherogenic role, but the molecular mechanisms have not been fully defined yet. We aimed to reveal if and how CXCL12 promoted atherosclerosis via regulating lipid metabolism. In vitro, our data showed that CXCL12 could reduce ABCA1 expression, and it mediated cholesterol efflux from THP-1-derived macrophages to apoA-I. Data from the luciferase reporter gene and chromatin immunoprecipitation assays revealed that transcription factor 21 (TCF21) stimulated the transcription of ABCA1 via binding to its promoter region, which was repressed by CXCL12. We found that CXCL12 increased the levels of phosphorylated glycogen synthase kinase 3β (GSK3β) and the phosphorylation of β-catenin at the Thr120 position. Inactivation of GSK3β or β-catenin increased the expression of TCF21 and ABCA1. Further, knockdown or inhibition of CXC chemokine receptor 4 (CXCR4) blocked the effects of CXCL12 on TCF21 and ABCA1 expression and the phosphorylation of GSK3β and β-catenin. In vivo, the overexpression of CXCL12 in Apoe^-/- mice via lentivirus enlarged the atherosclerotic lesion area and increased macrophage infiltration in atherosclerotic plaques. We further found that the overexpression of CXCL12 reduced the efficiency of reverse cholesterol transport and plasma HDL-C levels, decreased ABCA1 expression in the aorta and mouse peritoneal macrophages (MPMs), and suppressed cholesterol efflux from MPMs to apoA-I in Apoe^-/- mice. Collectively, these findings suggest that CXCL12 interacts with CXCR4 and then activates the GSK-3β/β-catenin^T120/TCF21 signaling pathway to inhibit ABCA1-dependent cholesterol efflux from macrophages and aggravate atherosclerosis. Targeting CXCL12 may be a novel and promising strategy for the prevention and treatment of atherosclerotic cardiovascular diseases.