Cholesterol Efflux Mechanisms in Atherosclerotic Macrophages

Macrophages in the arterial intima internalise modified low-density lipoproteins and transform into lipid-laden foam cells, a hallmark of early atherosclerotic lesions. To prevent foam cell accumulation and promote plaque regression, macrophages employ specialised efflux pathways that transport cholesterol to extracellular acceptors. Key membrane proteins—ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1), together with scavenger receptor class B type I (SR-B1)—mediate the transfer of free cholesterol to apolipoprotein A-I or high-density lipoprotein. These efflux systems are under the control of nuclear receptors, principally liver X receptor α (LXRα) and peroxisome proliferator-activated receptor γ (PPARγ), which sense intracellular lipid levels and coordinate transcriptional programmes for lipid disposal and anti-inflammatory responses. Additional layers of regulation involve microRNAs, post-translational modification of transporter proteins and cross-talk with signalling cascades such as p38/Elk-1. Efficient reverse cholesterol transport (RCT) from macrophages to the liver is therefore an integrated process that not only mitigates lipid overload but also dampens vascular inflammation, making efflux enhancement a compelling therapeutic strategy against cardiovascular disease.

Research from Nature Portfolio

Recent work has employed an interactomics strategy to reveal a direct small-molecule interaction with a cholesterol transporter. A bioactive alkaloid was shown to bind selectively to ABCA1, increasing its stability at the macrophage surface without altering transcript levels. Enhanced ABCA1 protein abundance led to more robust cholesterol export to apolipoprotein A-I, while levels of other transporters remained unchanged. This finding demonstrates the feasibility of targeting efflux machinery directly, opening new avenues for drug discovery aimed at augmenting macrophage cholesterol clearance within atherosclerotic plaques.

Cholesterol Efflux Mechanisms in Atherosclerotic Macrophages publication trend

The graph below shows the total number of articles in cholesterol efflux mechanisms in atherosclerotic macrophages across all publications each year (not limited to Nature Index journals).

Technical terms

Foam cell: Macrophage engorged with intracellular lipids, characteristic of early atherosclerotic lesions.

ABCA1: ATP-binding cassette transporter A1 that mediates cholesterol efflux to lipid-poor apolipoprotein A-I.

ABCG1: ATP-binding cassette transporter G1 responsible for transferring cholesterol to mature high-density lipoprotein particles.

LXRα: Nuclear receptor that senses oxysterols and up-regulates genes involved in cholesterol efflux and lipid metabolism.

PPARγ: Nuclear receptor that regulates lipid uptake, storage and anti-inflammatory gene expression in macrophages.

References

1. Novel interactomics approach identifies ABCA1 as direct target of evodiamine, which increases macrophage cholesterol efflux. Scientific Reports (2018).
2. Naringin Inhibits Macrophage Foam Cell Formation by Regulating Lipid Homeostasis and Metabolic Phenotype. Nutrients (2024).
3. Diterpenoids inhibit ox-LDL-induced foam cell formation in RAW264.7 cells by promoting ABCA1 mediated cholesterol efflux. Frontiers in Pharmacology (2023).
4. Asprosin inhibits macrophage lipid accumulation and reduces atherosclerotic burden by up-regulating ABCA1 and ABCG1 expression via the p38/Elk-1 pathway. Journal of Translational Medicine (2022).