Anionic nanoliposomes reduced atherosclerosis progression in Low Density Lipoprotein Receptor (LDLR) deficient mice fed a high fat diet

Oral Nanoformulations in Cardiovascular Medicine: Advances in Atherosclerosis Treatment

Atherosclerosis (AS) is the formation of atherosclerotic plaques on the walls of the arteries, causing them to narrow. If this occurs in the coronary arteries, the blood vessels may be completely blocked, resulting in myocardial infarction; if it occurs in the blood vessels of the brain, the blood vessels may be blocked, resulting in cerebral infarction, i.e., stroke. Studies have shown that the pathogenesis of atherosclerosis involves the processes of inflammation, lipid infiltration, oxidative stress, and endothelial damage, etc. SIRT, as a key factor regulating the molecular mechanisms of oxidative stress, inflammation, and aging, has an important impact on the pathogenesis of plaque formation, progression, and vulnerability. Statistics show that AS accounts for about 50 per cent of deaths in Western countries. Currently, oral medication is the mainstay of AS treatment, but its development is limited by side effects, low bioavailability and other unfavourable factors. In recent years, with the rapid development of nano-preparations, researchers have combined statins and natural product drugs within nanopreparations to improve their bioavailability. Based on this, this paper summarises the main pathogenesis of AS and also proposes new oral nanoformulations such as liposomes, nanoparticles, nanoemulsions, and nanocapsules to improve their application in the treatment of AS.

Negatively-charged Liposome Nanoparticles Can Prevent Dyslipidemia and Atherosclerosis Progression in the Rabbit Model

BACKGROUND AND AIM

Negatively charged nanoliposomes have a strong attraction towards plasma lipoprotein particles and can thereby regulate lipid metabolism. Here, the impact of such nanoliposomes on dyslipidaemia and progression of atherosclerosis was investigated in a rabbit model.

METHODS

Two sets of negatively-charged nanoliposome formulations including [Hydrogenated Soy Phosphatidylcholine (HSPC)/1,2-distearoyl-sn-glycero-3- phosphoglycerol (DSPG)] and [1,2- Dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC)/1,2-Dimyristoyl-sn-glycero-3-phosphorylcholine (DMPG)/Cholesterol] were evaluated. Rabbits fed a high-cholesterol diet were randomly divided into 3 groups (n=5/group) intravenously administrated with HSPC/DSPG formulation (DSPG group; 100 mmol/kg), DMPC/DMPG formulation (DMPG group; 100 mmol/kg), or the normal saline (control group; 0.9% NaCl) over a 4-week period. The atherosclerotic lesions of the aortic arch wall were studied using haematoxylin and eosin staining.

RESULTS

Both DSPG and DMPG nanoliposome formulations showed a nano-sized range in diameter with a negatively-charged surface and a polydispersity index of <0.1. After 4 weeks administration, the nanoliposome formulations decreased triglycerides (-62±3% [DSPG group] and -58±2% [DMPG group]), total cholesterol (-58±9% [DSPG group] and -37±5% [DMPG group]), and lowdensity lipoprotein cholesterol (-64±6% [DSPG group] and -53±10% [DMPG group]) levels, and increased high-density lipoprotein cholesterol (+67±28% [DSPG group] and +35±19% [DMPG group]) levels compared with the controls. The nanoliposomes showed a significant decrease in the severity of atherosclerotic lesions: mean values of the intima to media ratio in DMPG (0.96±0.1 fold) and DSPG (0.54±0.02 fold) groups were found to be significantly lower than that in the control (1.2±0.2 fold) group (p<0.05).

CONCLUSION

Anionic nanoliposomes containing [HSPC/DSPG] and [DMPC/DMPG] correct dyslipidaemia and inhibit the progression of atherosclerosis.

Liposome interaction with macrophages and foam cells for atherosclerosis treatment: effects of size, surface charge and lipid composition

Liposomes are potential drug carriers for atherosclerosis therapy due to low immunogenicity and ease of surface modifications that allow them to have prolonged circulation half-life and specifically target atherosclerotic sites to increase uptake efficiency. However, the effects of their size, charge, and lipid compositions on macrophage and foam cell behaviour are not fully understood. In this study, liposomes of different sizes (60 nm, 100 nm and 180 nm), charges (-40 mV, -20 mV, neutral, +15 mV and +30 mV) and lipid compositions (1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, L-a-phosphatidylcholine, and egg sphingomyelin) were synthesized, characterized and exposed to macrophages and foam cells. Compared to 100 nm neutral 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) liposomes, flow cytometry and confocal imaging indicated that cationic liposomes and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DSPC) liposomes were internalized more by both macrophages and foam cells. Through endocytosis inhibition, phagocytosis and clathrin-mediated endocytosis were identified as the dominant mechanisms of uptake. Anionic and DSPC liposomes induced more cholesterol efflux capacity in foam cells. These results provide a guide for the optimal size, charge, and lipid composition of liposomes as drug carriers for atherosclerosis treatment.

Complement Receptor Targeted Liposomes Encapsulating the Liver X Receptor Agonist GW3965 Accumulate in and Stabilize Atherosclerotic Plaques

Atherosclerosis is characterized by the retention of lipids in foam cells in the arterial intima. The liver X receptor (LXR) agonist GW3965 is a promising therapeutic compound, since it induces reverse cholesterol transport in foam cells. However, hepatic LXR activation increases plasma and liver lipid levels, inhibiting its clinical development. Herein, a formulation that specifically enhances GW3965 deposition in the atherosclerotic lesion is aimed to be developed. GW3965 is encapsulated in liposomes functionalized with the cyclic peptide Lyp-1 (CGNKRTRGC), which binds the p32 receptor expressed on foam cells. These liposomes show preferential uptake by foam cells in vitro and higher accumulation in atherosclerotic plaques in mice compared to non-targeted liposomes as determined by in vivo imaging. Flow cytometry analysis of plaques reveals increased retention of Lyp-1 liposomes in atherosclerotic plaque macrophages compared to controls (p < 0.05). Long term treatment of established plaques in LDLR -/- mice with GW3965-containing Lyp-1 liposomes significantly reduces plaque macrophage content by 50% (p < 0.01). Importantly, GW3965-containing Lyp-1 liposomes do not increase plasma or hepatic lipid content. Thus, GW3965-containing Lyp-1 liposomes successfully target the atherosclerotic macrophages allowing plaque stabilization without commonly observed side effects of LXR agonists.

A new approach to the diagnosis and treatment of atherosclerosis: the era of the liposome

The consequences of atherosclerotic cardiovascular disease (ASCVD) include myocardial infarction, ischemic stroke, and angina pectoris, which are major causes of mortality and morbidity worldwide. Despite current therapeutic strategies to reduce risk, patients still experience the consequences of ASCVD. Consequently, a current goal is to enhance visualization of early atherosclerotic lesions to improve residual ASCVD risk. The uses of liposomes, in the context of ASCVD, can include as contrast agents for imaging techniques, as well as for the delivery of antiatherosclerotic drugs, genes, and cells to established sites of plaque. Additionally, liposomes have a role as vaccine adjuvants against mediators of atherosclerosis. Here. we review the scientific and clinical evidence relating to the use of liposomes in the diagnosis and management of ASCVD.

Nanotherapies for Treatment of Cardiovascular Disease: A Case for Antioxidant Targeted Delivery

Purpose of Review

Cardiovascular disease (CVD) involves a broad range of clinical manifestations resulting from a dysfunctional vascular system. Overproduction of reactive oxygen and nitrogen species are causally implicated in the severity of vascular dysfunction and CVD. Antioxidant therapy is an attractive avenue for treatment of CVD associated pathologies. Implementation of targeted nano-antioxidant therapies has the potential to overcome hurdles associated with systemic delivery of antioxidants. This review examines the currently available options for nanotherapeutic targeting CVD, and explores successful studies showcasing targeted nano-antioxidant therapy.

Recent Findings

Active targeting strategies in the context of CVD heavily focus on immunotargeting to inflammatory markers like cell adhesion molecules, or to exposed extracellular matrix components. Targeted antioxidant nanotherapies have found success in pre-clinical studies.

Summary

This review underscores the potential of targeted nanocarriers as means of finding success translating antioxidant therapies to the clinic, all with a focus on CVD.

Therapeutic targets of hypercholesterolemia: HMGCR and LDLR

Cholesterol homeostasis is critical and necessary for the body's functions. Hypercholesterolemia can lead to significant clinical problems, such as cardiovascular disease (CVD). 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and low-density lipoprotein cholesterol receptor (LDLR) are major points of control in cholesterol homeostasis. We summarize the regulatory mechanisms of HMGCR and LDLR, which may provide insight for new drug design and development.

microRNA-338-3p promotes ox-LDL-induced endothelial cell injury through targeting BAMBI and activating TGF-β/Smad pathway

microRNAs (miRNAs) have been revealed to participate in the pathological process of atherosclerosis (AS). However, the exact role of miR-338-3p, a target miRNA of BMP and activin membrane-bound inhibitor (BAMBI), and its possible molecular mechanism in AS remain unidentified. In this study, we found that BAMBI was significantly decreased, whereas miR-338-3p increased in patients with AS and oxidized low-density lipoprotein (ox-LDL)-induced HUVEC cells. Furthermore, overexpression of miR-338-3p significantly decreased cell viability and elevated cell apoptosis, whereas its inhibition significantly promoted cell viability and inhibited cell apoptosis in ox-LDL-induced HUVEC cells. Moreover, miR-338-3p overexpression increased TGF-β/Smad pathway activation in ox-LDL-induced HUVEC cells. A dual-luciferase reporter assay confirmed the direct interaction between miR-338-3p and the 3'-untranslated region of BAMBI messenger RNA. Furthermore, the suppression of BAMBI ameliorated the effect of miR-338-3p inhibition against ox-LDL-induced HUVEC cell injury. In conclusion, our study thus suggests that miR-338-3p promoted ox-LDL-induced HUVEC cell injury by targeting BAMBI and activating the TGF-β/Smad pathway, which may provide a novel and promising therapeutic target for AS.

A diet enriched with tree nuts reduces severity of atherosclerosis but not abdominal aneurysm in angiotensin II-infused apolipoprotein E deficient mice

BACKGROUND AND AIMS

Diets enriched with tree nuts have been demonstrated to reduce the risk of atherosclerosis-related cardiovascular events. Abdominal aortic aneurysm (AAA) shares common risk factors with atherosclerosis and AAA patients commonly have atherosclerosis related cardiovascular events. AAA has some distinct pathological and clinical characteristics to those of atherosclerosis. No previous study has examined the effect of a diet enriched with tree nuts on experimental or clinical AAA. This study investigated the effect of a diet enriched with tree nuts on the development and severity of AAA within an experimental rodent model.

METHODS

Male apolipoprotein E deficient mice were allocated to a diet enriched with tree nuts or control diet for 56 days (n = 17 per group). After 28 days, all mice were infused with angiotensin II whilst being maintained on their respective diets. The primary outcome was AAA severity assessed by the supra-renal aortic diameter, measured by ultrasound and ex vivo morphometric analysis. The severity of atherosclerosis was assessed by computer-aided analysis of Sudan IV stained aortic arches and sections of brachiocephalic arteries prepared with Van Gieson's stain.

RESULTS

The diet enriched with tree nuts did not influence aortic diameter or aortic rupture incidence. Mice receiving the diet enriched with tree nuts had significantly less atherosclerosis within the brachiocephalic artery (p = 0.033) but not in the aortic arch.

CONCLUSIONS

This experimental study suggests that a diet enriched with tree nuts does not reduce the severity of AAA, but does reduce the severity of atherosclerosis within the brachiocephalic artery. The study was not powered to identify a moderate effect of the diet on the primary outcome and therefore this cannot be excluded.