Synergetic Effect of rHDL and LXR Agonist on Reduction of Atherosclerosis in Mice

Designing nanodiscs as versatile platforms for on-demand therapy

Nowadays, there has been an increasing utilization of nanomedicines for disease treatment. Nanodiscs (NDs) have emerged as a novel platform technology that garners significant attention in biomedical research and drug discovery. NDs are nanoscale phospholipid bilayer discs capable of incorporating membrane proteins and lipids within a native-like environment. They are assembled using amphiphilic biomacromolecular materials, such as apolipoprotein A1 or membrane scaffold proteins (MSPs), peptides, and styrene-maleic acid polymers (SMAs). NDs possess well-defined sizes and shapes, offering a stable, homogeneous, and biologically relevant environment for studying membrane proteins and lipids. Their unique properties have made them highly desirable for diverse applications, including cancer immunotherapy, vaccine development, antibacterial and antiviral therapy, and treating Alzheimer's disease (AD) and diabetes-related conditions. This review discusses the classifications, advantages, and applications of NDs in disease therapy.

Targeting Nanoplatform for Atherosclerosis Inhibition and Degradation via a Dual-Track Reverse Cholesterol Transport Strategy

As a main cause of serious cardiovascular diseases, atherosclerosis is characterized by deposited lipid and cholesterol crystals (CCs), which is considered as a great challenge to the current treatments. In this study, a dual-track reverse cholesterol transport strategy is used to overcome the cumulative CCs in the atherosclerotic lesions via a targeting nanoplatform named as LPLCH. Endowed with the active targeting ability to the plaques, the nanoparticles can be efficiently internalized and achieve a pH-triggered charge conversion for the escape from lysosomes. During this procedure, the liver X receptor (LXR) agonists loaded in nanoparticles are replaced by the deposited lysosomal CCs, leading to a LXR mediated up-regulation of ATP-binding cassette transporte ABCA1/G1 with the local CCs carrying at the same time. Thus, the cumulative CCs are removed in a dual-track way of ABCA1/G1 mediated efflux and nanoparticle-based carrying. The in vivo investigations indicate that LPLCH exhibits a favorable inhibition on the plaque progression and a further reversal of formed lesions when under a healthy diet. And the RNA-sequencing suggests that the cholesterol transport also synergistically activates the anti-inflammation effect. The dual-track reverse cholesterol transport strategy performed by LPLCH delivers an exciting candidate for the effective inhibition and degradation of atherosclerosis.

Efficacy and underlying mechanisms of berberine against lipid metabolic diseases: a review

Lipid-lowering therapy is an important tool for the treatment of lipid metabolic diseases, which are increasing in prevalence. However, the failure of conventional lipid-lowering drugs to achieve the desired efficacy in some patients, and the side-effects of these drug regimens, highlight the urgent need for novel lipid-lowering drugs. The liver and intestine are important in the production and removal of endogenous and exogenous lipids, respectively, and have an important impact on circulating lipid levels. Elevated circulating lipids predisposes an individual to lipid deposition in the vascular wall, affecting vascular function. Berberine (BBR) modulates liver lipid production and clearance by regulating cellular targets such as cluster of differentiation 36 (CD36), acetyl-CoA carboxylase (ACC), microsomal triglyceride transfer protein (MTTP), scavenger receptor class B type 1 (SR-BI), low-density lipoprotein receptor (LDLR), and ATP-binding cassette transporter A1 (ABCA1). It influences intestinal lipid synthesis and metabolism by modulating gut microbiota composition and metabolism. Finally, BBR maintains vascular function by targeting proteins such as endothelial nitric oxide synthase (eNOS) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). This paper elucidates and summarizes the pharmacological mechanisms of berberine in lipid metabolic diseases from a multi-organ (liver, intestine, and vascular system) and multi-target perspective.

Potential therapeutic targets for age-related macular degeneration: The nuclear option

The functions and activities of nuclear receptors, the largest family of transcription factors in the human genome, have classically focused on their ability to act as steroid and hormone sensors in endocrine organs. However, they are responsible for a diverse array of physiological functions, including cellular homeostasis and metabolism, during development and aging. Though the eye is not a traditional endocrine organ, recent studies have revealed high expression levels of nuclear receptors in cells throughout the posterior pole. These findings have precipitated an interest in investigating the role of these transcription factors in the eye as a function of age and ocular disease, in particular age-related macular degeneration (AMD). As the leading cause of vision impairment in the elderly, identifying signaling pathways that may be targeted for AMD therapy is of great importance, given the lack of therapeutic options for over 85% of patients with this disease. Herein we review this relatively new field and recent findings supporting the hypothesis that the eye is a secondary endocrine organ, in which nuclear receptors serve as the bedrock for biological processes in cells vulnerable in AMD, including retinal pigment epithelial and choroidal endothelial cells, and discuss the therapeutic potential of targeting these receptors for AMD.

A green-inspired method to prepare non-split high-density lipoprotein (HDL) carrier with anti-dysfunctional activities superior to reconstituted HDL

Numerous studies have demonstrated that dysfunctional high-density lipoprotein (HDL), especially oxidized HDL (OxHDL), could generate multifaceted in vivo proatherogenic effects that run counter to the antiatherogenic activities of HDL. It thereby reminded us that the in vitro reconstituted HDL (rHDL) might encountered with oxidation-induced dysfunction. Accordingly, a green-inspired method was employed to recycle non-split HDL from human plasma fraction IV. Then it was compared with rHDL formulated by an ethanol-injection method in terms of physicochemical properties and anti-dysfunctional activities. Results exhibited that rHDL oxidation extent exceeded that of non-split HDL evidenced by higher malondialdehy content, weaker inhibition on low-density lipoprotein (LDL) oxidation and more superoxide anion. The reserved paraoxonase-1 activity on non-split HDL could partially explain for above experimental results. In the targeted transport mechanism experiment, upon SR-BI receptor inhibition and/or CD36 receptor blockage, the almost unchanged non-split HDL uptake in lipid-laden macrophage indicated its negligible oxidation modification profile with regard to rHDL again. Furthermore, compared to rHDL, better macrophage biofunctions were observed for non-split HDL as illustrated by accelerated cholesterol efflux, inhibited oxidized LDL uptake and lessened cellular lipid accumulation. Along with decreased ROS secretion, obviously weakened oxidative stress damage was also detected under treatment with non-split HDL. More importantly, foam cells with non-split HDL-intervention inspired an enhanced inflammation repression and apoptosis inhibition effect. Collectively, the anti-dysfunctional activities of non-split HDL make it suitable as a potential nanocarrier platform for cardiovascular drug payload and delivery.

Opuntia dillenii Haw. Polysaccharide Promotes Cholesterol Efflux in THP-1-Derived Foam Cells via the PPARγ-LXRα Signaling Pathway

There is increasing evidence supporting a role for enhanced macrophage cholesterol efflux in ameliorating atherosclerosis. Opuntia dillenii Haw. polysaccharide (ODP-Ia), the most important functional component obtained from Opuntia dillenii Haw. stem, has anti-atherosclerosis effects. Therefore, we propose that ODP-Ia could promote cholesterol efflux via the PPARγ-LXRα signaling pathway. In this study, THP-1 foam cells derived from macrophages were treated with different concentrations of ODP-Ia, GGPP (antagonist of LXRα) and GW9662 (antagonist of PPARγ), with or without 15 nmol ODP-Ia. The total cholesterol content in the cells was measured. The mRNA of ABCA1, ABCG1, PPARγ, LXRα and their protein levels in the foam cells were detected by RT−PCR and Western blot, respectively. The results showed that ODP-Ia plays a role in significantly promoting cholesterol efflux (p < 0.05) by upregulating the expression of ABCA1, ABCG1, SR-BI, PPARγ, PPARα and LXRα. Meanwhile, PPARγ and LXRα antagonists dramatically interfered the cholesterol efflux mediated by ODP-Ia (p < 0.05) and dramatically inhibited the upregulating effect of ODP-Ia on the expression of PPARγ, LXRα, ABCA1 and ABCG1 at both protein and mRNA levels (p < 0.05). In conclusion, ODP-Ia promotes cholesterol efflux in the foam cells through activating the PPARγ-LXRα signaling pathway. This bioactivity suggested that ODP-Ia may be of benefit in treating atherosclerosis.

Liver X Receptor: a potential target in the treatment of atherosclerosis

INTRODUCTION

Liver X receptors (LXRs) are master regulators of atherogenesis. Their anti-atherogenic potential has been attributed to their role in the inhibition of macrophage-mediated inflammation and promotion of reverse cholesterol transport. Owing to the significance of their anti-atherogenic potential, it is essential to develop and test new generation LXR agonists, both synthetic and natural, to identify potential LXR-targeted therapeutics for the future.

AREAS COVERED

This review describes the role of LXRs in atherosclerotic development, provides a summary of LXR agonists and future directions for atherosclerosis research. We searched PubMed, Scopus and Google Scholar for relevant reports, from last 10 years, using atherosclerosis, liver X receptor, and LXR agonist as keywords.

EXPERT OPINION

LXRα has gained widespread recognition as a regulator of cholesterol homeostasis and expression of inflammatory genes. Further research using models of cell type-specific knockout and specific agonist-targeted LXR isoforms is warranted. Enthusiasm for therapeutic value of LXR agonists has been tempered due to LXRα-mediated induction of hepatic lipogenesis. LXRα agonism and LXRβ targeting, gut-specific inverse LXR agonists, investigations combining LXR agonists with other lipogenesis mitigating agents, like IDOL antagonists and synthetic HDL, and targeting ABCA1, M2 macrophages and LXRα phosphorylation, remain as promising possibilities.

Nanodisc delivery of liver X receptor agonist for the treatment of diabetic nephropathy

Dyslipidemia is recognized to be an important contributor to the progression of diabetic nephropathy (DN), leading to lipoprotein dysregulation, excessive mesangium expansion as well as inflammation in the glomeruli. Thus, dual targeting of abnormal cholesterol metabolism and inflammatory responses of mesangial cells represents an alternative approach for DN treatment. Herein, we sought to develop a renal-targeting therapeutic strategy for diabetic nephropathy by modifying synthetic high-density lipoprotein (sHDL) nanodiscs with a kidney targeting ligand (KT peptide) and encapsulating a liver X receptor (LXR) agonist in the modified sHDL. LXR agonists delivered by sHDL can facilitate the removal of excessive lipids from mesangial cells, ameliorate inflammation and restore normal renal function. Overall, our data suggests that our optimized KT-targeted sHDL/TO nanodiscs (KT-sHDL/TO) generate potent therapeutic efficacy not only by more efficient cholesterol efflux, but also by suppressing mesangial cell proliferation. Most importantly, in a DN murine model, KT-sHDL/TO ameliorated dyslipidemia and inflammation superior to blank sHDL and non-targeting sHDL/TO formulations, showing promise for future clinical translation in DN treatment.

(r)HDL in theranostics: how do we apply HDL's biology for precision medicine in atherosclerosis management?

High-density lipoproteins (HDL) are key players in cholesterol metabolism homeostasis since they are responsible for transporting excess cholesterol from peripheral tissues to the liver. Imbalance in this process, due to either excessive accumulation or impaired clearance, results in net cholesterol accumulation and increases the risk of cardiovascular disease (CVD). Therefore, significant effort has been focused on the development of therapeutic tools capable of either directly or indirectly enhancing HDL-guided reverse cholesterol transport (RCT). More recently, in light of the emergence of precision nanomedicine, there has been renewed research interest in attempting to take advantage of the development of advanced recombinant HDL (rHDL) for both therapeutic and diagnostic purposes. In this review, we provide an update on the different approaches that have been developed using rHDL, focusing on the rHDL production methodology and rHDL applications in theranostics. We also compile a series of examples highlighting potential future perspectives in the field.