Protective Effect of ApoA1 (Apolipoprotein A1)-Milano in a Rat Model of Large Vessel Occlusion Stroke

Regulation of Platelet Function by HDL

Over the past decade, increasing the capacity of HDL (high-density lipoprotein) cholesterol to mediate macrophage reverse cholesterol transport has been a target of interest in the treatment of cardiovascular diseases (CVDs). However, clinical studies reporting the limited efficacy of HDL or its main apolipoprotein, APOA1, in reducing cardiovascular events have emerged. Although HDL cholesterol is unlikely to play a direct causal role in CVD, its inverse, albeit modest, association with CVD risk, consistently observed in large population studies, suggests it may influence alternative pathways beyond cholesterol metabolism. Given the diverse functions of HDL and its components, it is conceivable that its impact on CVD occurs through less direct mechanisms. A potential hypothesis is that HDL modulates platelet function, a crucial player in the initiation and progression of atherothrombosis, which may contribute to its observed relationship with CVD risk. In this review, we focus on how HDL and its components, with an emphasis on APOA1, interact with platelets (and their precursors or activation products) to modulate atherothrombotic responses.

HDL-replacement therapy: From traditional to emerging clinical applications

The unique and multifaceted properties of high-density lipoproteins (HDL)-ranging from cholesterol efflux to anti-inflammatory, anti-oxidant, and immunomodulatory effects-have prompted their direct use, particularly in cardiovascular ischemic conditions. Recent advances have extended the interest in HDL-based treatments to novel applications, from improving stent biocompatibility, to treatment of heart failure to central nervous system (CNS) disorders. Strategies to harness HDL's therapeutic potential have evolved from the direct use of isolated HDL in animal models to reconstituted HDL (rHDL) in humans. For these latter, the use of isolated apoA-I associated with different phospholipids has been the most frequent approach, also involving apparently beneficial mutants, such as the apo A-I Milano (AIM). From the initial very promising results, particularly with this mutant in coronary patients, later studies have mostly been non-confirmatory, although issues such as possible inadequate dose/response and unexpected immunological properties have come to light. Most recently a study on isolated plasma HDL in coronary patients (AEGIS-II) provided overall negative findings, but a clear fall of major cardiovascular events was recorded when restricting analysis to hypercholesterolemic patients. Emerging approaches, including gene therapy and plant-derived recombinant HDL formulations, hold promise for enhancing the accessibility and efficacy of HDL-based interventions. At this time, an improved approach to heart failure treatment also appears feasible, and a better understanding of the role played by HDL in the CNS may lead to significant improvements in the handling of some dramatic diseases at this level. While challenges persist, the evolving landscape of HDL replacement therapies offers hope for significant progress in addressing both cardiovascular and non-cardiovascular conditions.

Validation of the role of apolipoproteins in coronary artery disease patients with impaired kidney function for prognosis: a prospective cohort study in China

OBJECTIVE

This study aims to evaluate the relationship between apolipoproteins (ApoA1, ApoB, and the ApoB/A1 ratio) and the incidence of major adverse cardiovascular events (MACE) in patients with coronary artery disease (CAD) and impaired kidney function, assessing their potential role in secondary prevention.

METHOD

A prospective cohort of 1,640 patients with impaired kidney function who underwent percutaneous coronary intervention in China was analyzed. Patients were categorized based on the measurements of ApoA1, ApoB, and ApoB/A1 ratio. MACE, defined as a composite of all-cause mortality, cardiovascular death, nonfatal myocardial infarctions, strokes, and unplanned revascularizations, was tracked post-procedure, with statistical analyses including Kaplan-Meier survival curves and Cox regression models to identify associations with apolipoproteins. Subgroup analyses according to kidney function were conducted.

RESULT

During a median follow-up of 3.1 years, 324 MACE events were observed. Multivariable Cox regression analyses illustrated higher levels of ApoB and the ApoB/A1 ratio were significantly associated with increased MACE incidence (adjusted HR [95%CI] 1.668[1.044-2.666]; adjusted HR [95%CI] 2.231[1.409-3.533], respectively), while lower ApoA1 levels correlated with a higher risk (adjusted HR [95%CI] 0.505[0.326-0.782]). ROC curve analyses indicated comparable predictive performances to traditional risk factors like LDL cholesterol. Subgroup analysis revealed that the above association was not statistically significant in the moderate-to-severe renal impairment CAD patients (eGFR < 45 mL/min/1.73 m2).

CONCLUSION

Our findings illustrate that apolipoproteins, specifically ApoA1 and ApoB, along with their ratio, are significant predictors of major adverse cardiovascular events in CAD patients with impaired kidney function. These results emphasize the need for incorporating apolipoprotein measurements in secondary prevention strategies for this high-risk population.

Cholesterol transport and beyond: Illuminating the versatile functions of HDL apolipoproteins through structural insights and functional implications

High-density lipoproteins (HDLs) play a vital role in lipid metabolism and cardiovascular health, as they are intricately involved in cholesterol transport and inflammation modulation. The proteome of HDL particles is indeed complex and distinct from other components in the bloodstream. Proteomics studies have identified nearly 285 different proteins associated with HDL; however, this review focuses more on the 15 or so traditionally named "apo" lipoproteins. Important lipid metabolizing enzymes closely working with the apolipoproteins are also discussed. Apolipoproteins stand out for their integral role in HDL stability, structure, function, and metabolism. The unique structure and functions of each apolipoprotein influence important processes such as inflammation regulation and lipid metabolism. These interactions also shape the stability and performance of HDL particles. HDLs apolipoproteins have multifaceted roles beyond cardiovascular diseases (CVDs) and are involved in various physiological processes and disease states. Therefore, a detailed exploration of these apolipoproteins can offer valuable insights into potential diagnostic markers and therapeutic targets. This comprehensive review article aims to provide an in-depth understanding of HDL apolipoproteins, highlighting their distinct structures, functions, and contributions to various physiological processes. Exploiting this knowledge holds great potential for improving HDL function, enhancing cholesterol efflux, and modulating inflammatory processes, ultimately benefiting individuals by limiting the risks associated with CVDs and other inflammation-based pathologies. Understanding the nature of all 15 apolipoproteins expands our knowledge of HDL metabolism, sheds light on their pathological implications, and paves the way for advancements in the diagnosis, prevention, and treatment of lipid and inflammatory-related disorders.

Lipoprotein Particles in Cerebrospinal Fluid

The brain is the most lipid-rich organ in the body, and the intricate interplay between lipid metabolism and pathologies associated with neurodegenerative disorders is being increasingly recognized. The brain is bathed in cerebrospinal fluid (CSF), which, like plasma, contains lipid-protein complexes called lipoproteins that are responsible for extracellular lipid transport. Multiple CSF lipoprotein populations exist, some of which are produced de novo in the central nervous system and others that appear to be generated from protein constituents that are produced in the periphery. These CSF lipoproteins are thought to play key roles in maintaining lipid homeostasis in the central nervous system, while little else is known due to their limited accessibility and their low abundance in CSF. Recent work has provided new insights into the compositional complexity of CSF lipoprotein families and their metabolism in cerebral circulation. The purpose of this review is to summarize our current state of knowledge on the composition, origin, and metabolism of CSF lipoproteins.

Combined with dynamic serum proteomics and clinical follow-up to screen the serum proteins to promote the healing of diabetic foot ulcer

OBJECTIVE

Non-healing diabetic foot ulcers are a leading cause of disability and death in diabetic patients, which often results in lower limb amputation. This study aimed to investigate the impact of biomarkers on the healing of diabetic foot ulcers by utilizing dynamic serum proteomics and skin proteomic analysis, combined with clinical case follow-up studies.

METHODS

To analyze dynamic serum proteomic changes in four groups, age-matched normal subjects, diabetic patients, pretreatment diabetic foot ulcer patients, and healed diabetic foot ulcer patients were selected. The differential proteins were screened in conjunction with normal and diabetic foot ulcer skin proteomics. In this study, a total of 80 patients with diabetic foot ulcers were enrolled and monitored for 3-6 months during treatment. To verify the significance of the differential proteins, age-matched diabetic patients (240 patients) and healthy controls (160 patients) were included as controls.

RESULTS

Dynamic serum proteomics trend showed that the level of negative regulatory proteins related to endothelial cell migration, angiogenesis, and vascular development was significantly decreased after treatment of diabetic foot ulcer. GO enrichment analysis suggested that differentially expressed proteins were mainly enriched in protein activation cascade, immunoglobulin production, and complement activation. The researchers identified the core proteins APOA1, LPA, and APOA2 through a convergence of serum and skin proteomics screening. Clinical cases further validated that APOA1 levels are decreased in diabetic foot ulcer patients and are correlated with disease severity. In addition, animal experiments showed that APOA1 could promote wound healing in diabetic mice.

CONCLUSIONS

Based on our dynamic proteomics and clinical case studies, our bioinformatic analysis suggests that APOA1 plays a critical role in linking coagulation, inflammation, angiogenesis, and wound repair, making it a key protein that promotes the healing of diabetic foot ulcers.

Identification of serum exosomal metabolomic and proteomic profiles for remote ischemic preconditioning

BACKGROUND

Remote ischemic preconditioning (RIPC) refers to a brief episode of exposure to potential adverse stimulation and prevents injury during subsequent exposure. RIPC has been shown to increase tolerance to ischemic injury and improve cerebral perfusion status. Exosomes have a variety of activities, such as remodeling the extracellular matrix and transmitting signals to other cells. This study aimed to investigate the potential molecular mechanism of RIPC-mediated neuroprotection.

METHODS

Sixty adult male military personnel participants were divided into the control group (n = 30) and the RIPC group (n = 30). We analyzed the differential metabolites and proteins in the serum exosomes of RIPC participants and control subjects.

RESULTS

Eighty-seven differentially expressed serum exosomal metabolites were found between the RIPC and control groups, which were enriched in pathways related to tyrosine metabolism, sphingolipid metabolism, serotonergic synapses, and multiple neurodegeneration diseases. In addition, there were 75 differentially expressed exosomal proteins between RIPC participants and controls, which involved the regulation of insulin-like growth factor (IGF) transport, neutrophil degranulation, vesicle-mediated transport, etc. Furthermore, we found differentially expressed theobromine, cyclo gly-pro, hemopexin (HPX), and apolipoprotein A1 (ApoA1), which are associated with neuroprotective benefits in ischemia/reperfusion injury. In addition, five potential metabolite biomarkers, including ethyl salicylate, ethionamide, piperic acid, 2, 6-di-tert-butyl-4-hydroxymethylphenol and zerumbone, that separated RIPC from control individuals were identified.

CONCLUSION

Our data suggest that serum exosomal metabolites are promising biomarkers for RIPC, and our results provide a rich dataset and framework for future analyses of cerebral ischemia‒reperfusion injury under ischemia/reperfusion conditions.

A Study on Multiple Facets of Apolipoprotein A1 Milano

For several strategies formulated to prevent atherosclerosis, Apolipoprotein A1 Milano (ApoA1M) remains a prime target. ApoA1M has been reported to have greater efficiency in reducing the incidence of coronary artery diseases. Furthermore, recombinant ApoA1M based mimetic peptide exhibits comparatively greater atheroprotective potential, offers a hope in reducing the burden of atherosclerosis in in vivo model system. The aim of this review is to emphasize on some of the observed ApoA1M structural and functional effects that are clinically and therapeutically meaningful that might converge on the basic role of ApoA1M in reducing the chances of glycation assisted ailments in diabetes. We also hypothesize that the nonenzymatic glycation prone arginine amino acid of ApoA1 gets replaced with cysteine residue and the rate of ApoA1 glycation may decrease due to change substitution of amino acid. Therefore, to circumvent the effect of ApoA1M glycation, the related mechanism should be explored at the cellular and functional levels, especially in respective experimental disease model in vivo.

Data-Independent Acquisition-Based Serum Proteomic Profiling of Adult Moyamoya Disease Patients Reveals the Potential Pathogenesis of Vascular Changes

Moyamoya disease (MMD) is a chronic cerebrovascular disease with unknown etiology. The pathogenesis of vascular changes remains unclear. Ischemic and hemorrhagic adult MMD patients and healthy volunteers were enrolled to collect serum for data-independent acquisition (DIA)-based proteomic analysis and ELISA validation. DIA serum proteomic revealed that apolipoprotein C-I (APOC1), apolipoprotein D (APOD), and apolipoprotein A-IV (APOA4) were decreased. The reductases glutathione S-transferase omega-1 (GSTO1) and peptidyl-prolyl cis-trans isomerase A (PPIA) were upregulated, and ADAMTS-like protein 4 (ADAMTSL4) was downregulated in both ischemic and hemorrhagic MMD. Afamin (AFM) and transforming growth factor-beta-induced protein ig-h3 (TGFBI) increased in ischemic patients but decreased in hemorrhagic patients. Serum ELISA results confirmed that APOA4, APOC1, and APOD were decreased compared to controls. Then, we retrospectively analyzed biochemical indexes of 200 MMD patients. A total of 54 enrolled MMD patients showed decreased total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-c). APOA4, APOC1, and APOD were vital factors in the HDL decrease in MMD patients. Lipoprotein dysfunction in MMD patients is involved in MMD. Intimal thickening by enhanced adhesion, middle layer vascular smooth muscle cell migration, and decreased lipid antioxidant function represented by HDL are potential pathogeneses of vascular changes in MMD.

Leveraging knowledge of HDLs major protein ApoA1: Structure, function, mutations, and potential therapeutics

Apolipoprotein A1 (ApoA1) is a member of the Apolipoprotein family of proteins. It's a vital protein that helps in the production of high-density lipoprotein (HDL) particles, which are crucial for reverse cholesterol transport (RCT). It also has anti-inflammatory, anti-atherogenic, anti-apoptotic, and anti-thrombotic properties. These functions interact to give HDL particles their cardioprotective characteristics. ApoA1 has recently been investigated for its potential role in atherosclerosis, diabetes, neurological diseases, cancer, and certain infectious diseases. Since ApoA1's discovery, numerous mutations have been reported that affect its structural integrity and alter its function. Hence these insights have led to the development of clinically relevant peptides and synthetic reconstituted HDL (rHDL) that mimics the function of ApoA1. As a result, this review has aimed to provide an organized explanation of our understanding of the ApoA1 protein structure and its role in various essential pathways. Furthermore, we have comprehensively reviewed the important ApoA1 mutations (24 mutations) that are reported to be involved in various diseases. Finally, we've focused on the therapeutic potentials of some of the beneficial mutations, small peptides, and synthetic rHDL that are currently being researched or developed, since these will aid in the development of novel therapeutics in the future.

APOA1 mRNA and protein in kidney renal clear cell carcinoma correlate with the disease outcome

Renal cancer is one of the most common malignant tumors with high mortality, and kidney renal clear cell carcinoma (KIRC) is the most common type of renal cancer. We attempted to evaluate the clinical and prognostic significance of Apolipoprotein A1 (APOA1) mRNA and protein in KIRC patients. Clinical data along with RNA-sequencing data were downloaded from UCSC Xena. The Human Protein Atlas database was searched to reveal APOA1 protein expression profiles in KIRC and normal renal tissues. The TIMER database was applied to determine the correlations of APOA1 with immune cells and PD-1 and PD-L1 in KIRC. Ninety-one cases of KIRC patients and 93 healthy controls from our hospital were enrolled for clinical validation. Levels of APOA1 mRNA in KIRC tissues (N = 535) are not only lower than the levels in normal renal tissues (N = 117), but also in paired normal renal tissues (N = 72). High expression of APOA1 mRNA at the time of surgery was correlated with worse overall survival (OS) (HR 1.66; p = 0.037) and disease-free survival (DFS) (HR 1.65; p = 0.047), and APOA1 DNA methylation was linked to worse OS (HR 2.1; p = 0.001) rather than DFS (HR 1.12; p = 0.624) in KIRC patients. Concentrations of preoperative serum APOA1 protein were markedly decreased in KIRC patients compared to healthy controls (p < 0.01), and low levels of APOA1 protein predicted less favorable OS than those with high levels (HR = 2.84, p = 0.0407). APOA1 negatively correlated with various immune cell infiltrates and PD-L1 expression (r = − 0.283, p = 2.74e−11) according to the TIMER database. Low levels of APOA1 mRNA at the time of surgery predict favorable survival in KIRC patients. Our results provide insights to identify a novel prognostic index with great clinical utility.

Current Understanding of the Immunomodulatory Activities of High-Density Lipoproteins

Lipoproteins interact with immune cells, macrophages and endothelial cells - key players of the innate and adaptive immune system. High-density lipoprotein (HDL) particles seem to have evolved as part of the innate immune system since certain HDL subspecies contain combinations of apolipoproteins with immune regulatory functions. HDL is enriched in anti-inflammatory lipids, such as sphingosine-1-phosphate and certain saturated lysophospholipids. HDL reduces inflammation and protects against infection by modulating immune cell function, vasodilation and endothelial barrier function. HDL suppresses immune cell activation at least in part by modulating the cholesterol content in cholesterol/sphingolipid-rich membrane domains (lipid rafts), which play a critical role in the compartmentalization of signaling pathways. Acute infections, inflammation or autoimmune diseases lower HDL cholesterol levels and significantly alter HDL metabolism, composition and function. Such alterations could have a major impact on disease progression and may affect the risk for infections and cardiovascular disease. This review article aims to provide a comprehensive overview of the immune cell modulatory activities of HDL. We focus on newly discovered activities of HDL-associated apolipoproteins, enzymes, lipids, and HDL mimetic peptides.

MicroRNA in cardio-metabolic disorders

Hyperlipidemia is correlated with several health problems that contain the combination of hypertension, obesity, and diabetes mellitus, which are grouped as metabolic syndrome. Though the lipid-lowering agents, such as statins, which aims to reduce serum low-density lipoprotein cholesterol (LDL-C) has been considered as one of the most effective therapeutics in treating hyperlipidemia and coronary artery diseases, the persistent high risk of atherosclerosis after intensive lipid-lowering therapy could not be simply explained by hyperlipidemia. Therefore, it is necessary to identify novel factors to manage treatment and to predict risk of cardio-metabolic events. Endeavor over the past several decades has demonstrated the important functions of microRNAs in modulating macrophage activation, lipid metabolism, and hyperlipidemia. In the present review, we summarized the recent findings which highlighted the contributions of microRNAs in regulating serum lipid metabolism. Furthermore, we also provided the potential mechanisms whereby microRNAs controlled lipid metabolism and the risk of cardio-metabolic disorders, which could help us to identify microRNAs as a promising therapeutic target for hyperlipidemia and its related cardiovascular diseases.

Transendothelial transport of lipoproteins

The accumulation of low-density lipoproteins (LDL) in the arterial wall plays a pivotal role in the initiation and pathogenesis of atherosclerosis. Conversely, the removal of cholesterol from the intima by cholesterol efflux to high density lipoproteins (HDL) and subsequent reverse cholesterol transport shall confer protection against atherosclerosis. To reach the subendothelial space, both LDL and HDL must cross the intact endothelium. Traditionally, this transit is explained by passive filtration. This dogma has been challenged by the identification of several rate-limiting factors namely scavenger receptor SR-BI, activin like kinase 1, and caveolin-1 for LDL as well as SR-BI, ATP binding cassette transporter G1, and endothelial lipase for HDL. In addition, estradiol, vascular endothelial growth factor, interleukins 6 and 17, purinergic signals, and sphingosine-1-phosphate were found to regulate transendothelial transport of either LDL or HDL. Thorough understanding of transendothelial lipoprotein transport is expected to elucidate new therapeutic targets for the treatment or prevention of atherosclerotic cardiovascular disease and the development of strategies for the local delivery of drugs or diagnostic tracers into diseased tissues including atherosclerotic lesions.