Ldl-stimulated microglial activation exacerbates ischemic white matter damage

Area of Science:

• Neuroscience
• Immunology
• Cerebrovascular Biology

Background:

• The role of microglia in blood-brain barrier (BBB) impairment and white matter damage following chronic cerebral hypoperfusion remains poorly understood.
• Microglia are the primary immune cells of the central nervous system, responding to injury and disease.

Purpose of the Study:

• To investigate the specific mechanisms by which microglia contribute to BBB breakdown and white matter damage in chronic cerebral hypoperfusion.
• To identify the molecular triggers and cellular responses of microglia in this pathological context.

Main Methods:

• Utilized models of chronic cerebral hypoperfusion.
• Investigated the interaction between plasma low-density lipoprotein (LDL) leakage and microglia activation.
• Analyzed microglial phagocytosis, lipid burden, and inflammatory/regenerative profiles.
• Employed microglia-specific knockdown of LDL receptor (LDLR) and systemic LDL-lowering medication.

Main Results:

• Vessel-adjacent microglia were specifically activated by leaked plasma LDL, leading to BBB breakdown and ischemic demyelination.
• LDL stimulation enhanced microglial phagocytosis of myelin debris, resulting in lipid-laden microglia with suppressed inflammatory and pro-regenerative properties.
• Microglia-specific LDLR knockdown and systemic LDL reduction conferred protection against ischemic demyelination.

Conclusions:

• LDL-stimulated, vessel-adjacent microglia exhibit a unique molecular signature with suppressed regenerative capacity, exacerbating demyelination in ischemic white matter damage.
• Targeting LDL levels or LDLR in microglia presents a potential therapeutic strategy for mitigating white matter injury in chronic cerebral hypoperfusion.