Even aggressive statin therapy leaves a troubling gap in cardiovascular protection — residual risk that conventional lipid metrics fail to explain. A growing body of mechanistic research suggests this gap may be rooted in how macrophages die inside arterial plaques, and whether their death promotes or sabotages cholesterol clearance. Understanding this crosstalk could reshape how cardiometabolic disease is approached beyond LDL reduction.
This review from Frontiers in Cardiovascular Medicine systematically maps the bidirectional relationships between four programmed macrophage death modalities — apoptosis, pyroptosis, necroptosis, and ferroptosis — and cholesterol efflux machinery within atherosclerotic plaques. Apoptosis, when followed by efficient efferocytosis (the phagocytic clearance of dead cells), may preserve plaque stability and activate LXR-dependent transcriptional programs that upregulate ABCA1 and ABCG1 cholesterol exporters. However, when efferocytosis fails, apoptotic cells undergo secondary necrosis, amplifying local inflammation. Pyroptosis, necroptosis, and ferroptosis appear to converge on shared mechanisms — oxidative stress, membrane disruption, NLRP3-linked inflammatory cascades, and suppression of ABCA1/ABCG1-mediated reverse cholesterol transport — that collectively impair HDL loading and accelerate foam cell pathology. Autophagy occupies a nuanced middle ground: regulated autophagic flux mobilizes cholesterol from lipid droplets via lipophagy, but dysregulated autophagy can trigger ferritinophagy, releasing labile iron that potentiates GPX4 loss and ferroptotic vulnerability.
This synthesis is analytically valuable because it frames atherosclerosis not merely as a cholesterol-delivery problem but as a macrophage-biology problem with multiple mechanistic entry points. The field has long focused on RCT quantitatively; this framework adds qualitative dimensions — the mode and context of macrophage death matter as much as cholesterol flux rates. Key limitations apply: the evidence base spans in vitro systems, mouse models, and human plaque histology unevenly, and causal directionality between death modalities and efflux impairment remains incompletely established in humans. Still, for adults managing cardiovascular risk beyond lipid panels, this mechanistic landscape suggests that future therapeutics targeting efferocytosis efficiency, NLRP3 inhibition, or GPX4 preservation could meaningfully reduce residual plaque vulnerability.