Atherosclerosis Hijacks Brain Immunity Through Exosome Signals

Atherosclerosis is already known to raise the risk of stroke and dementia, but exactly how plaque-laden arteries impair brain function independently of blood flow has been poorly understood. This study from Tongji Hospital, published in Cell Metabolism, addresses that gap with a mechanistic answer involving extracellular vesicles.

The research team focused on exosomes — nanoscale vesicles secreted by cells that carry bioactive cargo including microRNAs, proteins, and lipids. They found that macrophages loaded with oxidized lipids (foam cells), a hallmark of atherosclerosis, release exosomes that circulate systemically and are preferentially taken up by microglia, the brain's resident immune cells.

Once internalized, these foam cell-derived exosomes deliver miR-101-3p, which suppresses the transcription factor Nrf2 and downstream glucose transporter Slc2a1. This cascade impairs the microglial antioxidant response and disrupts mitochondrial energy metabolism, leaving white matter more vulnerable to ischemic insult and accelerating vascular cognitive impairment.

Critically, the team showed the pathway is therapeutically actionable. Anti-miR-101-3p treatment, as well as genetic or pharmacological activation of Nrf2, each blocked the harmful exosome effects and improved cognitive outcomes in animal models. This suggests both RNA-targeting and established Nrf2-activating compounds could be repurposed to protect the brain in atherosclerosis patients.

The work establishes a molecular bridge between peripheral lipid-driven inflammation and central nervous system dysfunction, reframing VCI as partly an exosome-mediated metabolic disease. Caveats include reliance on animal and cell models; human validation and pharmacokinetic optimization of anti-miR or Nrf2 strategies will be needed before clinical translation.