Brain endothelial cells as phagocytes: mechanisms and implications.

Area of Science:

• Neuroscience
• Cell Biology
• Immunology

Background:

• Brain microvascular endothelial cells (BECs) form the blood-brain barrier (BBB), traditionally viewed as a passive barrier.
• Emerging evidence suggests BECs possess phagocytic capabilities, challenging conventional understanding.
• This phagocytosis is critical for maintaining brain homeostasis and responding to pathological conditions.

Purpose of the Study:

• To review the phagocytic capacity of BECs.
• To summarize the mechanisms underlying BEC phagocytosis.
• To discuss the clinical implications of BEC phagocytosis in brain health and disease.

Main Methods:

• Literature review of studies on BEC phagocytosis.
• Analysis of mechanisms including phosphatidylserine exposure, adhesion molecules (ICAM-1, VCAM-1), opsonization, and cytoskeleton remodeling.
• Examination of clinical relevance in conditions like capillary stalling, debris clearance, and hemorrhagic lesions.

Main Results:

• BECs actively phagocytose diverse cargos like aged red blood cells (RBCs), myelin debris, and embolic particles.
• Phagocytosis is triggered by specific molecular cues and involves cytoskeletal changes.
• BEC phagocytosis plays roles in regulating microvascular patency, clearing debris, and contributing to hemorrhagic lesions.

Conclusions:

• BECs function as non-professional phagocytes, significantly impacting brain homeostasis.
• Understanding BEC phagocytosis mechanisms is key to addressing neurological disorders.
• Further research is needed to fully elucidate the complexities and therapeutic potential of BEC phagocytosis.