Brain Endothelial Gene Tweak Blocks Stroke Inflammation and Shields the Blood-Brain Barrier

Ischemic stroke is one of the leading causes of death and long-term disability worldwide. Beyond the initial ischemic insult, a profound secondary inflammatory response amplifies brain injury—with peripherally derived macrophages playing a central pathological role. Until now, research has largely focused on immune-cell-intrinsic mechanisms, leaving the immunomodulatory capacity of cerebral endothelial cells underappreciated.

Using single-cell RNA sequencing of post-stroke brain tissue, the authors mapped extensive transcriptional reprogramming in cerebral endothelial cells and identified atypical chemokine receptor 1 (ACKR1)—also known as the Duffy antigen receptor for chemokines—as one of the most prominently upregulated genes. ACKR1 is a scavenger receptor known to sequester pro-inflammatory chemokines without triggering classical G-protein signaling, thereby modulating leukocyte trafficking across vascular barriers.

To test ACKR1's functional role, the team delivered an endothelial-specific AAV serotype (AAV-X1.1) carrying ACKR1 into mice prior to transient middle cerebral artery occlusion (tMCAO), a standard model of ischemic stroke. At 1 day post-stroke, ACKR1-overexpressing mice showed markedly better blood-brain barrier (BBB) integrity: tight junction protein ZO-1 continuity was maintained, pericyte and astrocytic endfoot coverage was enhanced, and leakage of both exogenous tracers and endogenous IgG was reduced. By day 3, macrophage infiltration into the ischemic territory was substantially curtailed, infarct volumes were smaller, and neurological deficit scores were improved. These benefits persisted through 28 days, with animals showing superior sensorimotor recovery on behavioral tests and significantly attenuated brain atrophy compared to controls.

Mechanistically, the data point to ACKR1's chemokine-scavenging function as the key driver: by sequestering inflammatory chemokines at the endothelial surface, ACKR1 reduces the chemotactic gradient that draws blood-borne macrophages into ischemic brain tissue. Preserving barrier integrity early likely creates a protective feedback loop, preventing further inflammatory amplification. The study thus identifies cerebral endothelial cells as active, programmable participants in post-stroke neuroinflammation rather than mere structural conduits.

These findings carry important translational implications. Endothelial-targeted AAV delivery is an increasingly feasible clinical approach, and ACKR1 represents a mechanistically grounded target at the vascular-immune interface. However, work in a single mouse model with a single AAV construct limits immediate generalizability, and the precise chemokine ligands and downstream signaling intermediates mediating ACKR1's protective effects in the brain remain to be fully characterized.