Perivascular macrophages (PvMs) are CNS border-associated macrophages (BAMs) that reside in the perivascular space alongside cerebral blood vessels. These cells play critical roles in:
Clearing waste metabolites from the brain interstitial space
Immune surveillance of the neurovascular unit
Regulation of cerebral blood flow through vascular smooth muscle cell interaction
Drainage of solutes via the glymphatic/perivascular pathway
In neurodegenerative diseases, PvM function declines, contributing to accumulation of toxic proteins (Aβ, tau, α-syn) and impaired neurovascular coupling.
Mechanistic Rationale
Enhanced Perivascular Clearance: PvMs are key effectors of perivascular waste drainage. Boosting their phagocytic activity can enhance clearance of Aβ, tau oligomers, and other toxic metabolites.
Immune Modulation: PvMs produce anti-inflammatory cytokines (IL-10, TGF-β) that can be enhanced to reduce neuroinflammation without compromising host defense.
Vascular Health: PvMs regulate endothelial health and pericyte function. Therapeutic modulation can improve cerebral blood flow and neurovascular coupling.
Disease Modification: By enhancing waste clearance and reducing neuroinflammation at the vascular interface, this approach targets two root causes simultaneously.
Therapeutic Mechanisms
PvM Activation: Use of CD36 agonists, SR-A1 modulators to enhance phagocytic clearance
Anti-inflammatory Polarization: IL-4/IL-13 delivery to promote M2 polarization
Pericyte Cooperation: PDGFR-β agonists to improve pericyte-PvM coordination
Combination: Pair with BBB modulation for enhanced drug delivery
Evidence Base
PvM numbers decline in aging and AD brain (Betzel 2021)
PvM dysfunction correlates with Aβ accumulation (Gutierrez 2023)