Proliferative Diabetic Retinopathy Microenvironment Drives Microglial Polarization and Promotes Angiogenesis and...

Area of Science:

• Ophthalmology
• Immunology
• Cell Biology

Background:

• Diabetic retinopathy (DR) is a leading cause of vision loss, with proliferative DR (PDR) posing significant risks.
• The role of microglia, the central nervous system's immune cells, in PDR pathogenesis remains largely undefined.
• Understanding microglial responses to the PDR microenvironment is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the role of microglia in proliferative diabetic retinopathy (PDR) progression.
• To analyze microglial gene expression changes under conditions mimicking the PDR microenvironment (hypoxia and inflammation).
• To identify specific molecular pathways involved in microglial-mediated PDR pathology.

Main Methods:

• Human-induced pluripotent stem cell-derived microglia were cultured under various stimuli (DMOG for hypoxia, LPS for inflammation, and combined).
• Comprehensive gene expression analysis was performed to identify differentially expressed genes.
• Key signaling pathways, including COX-2/PGE2/EP2, were investigated.

Main Results:

• Distinct microglial gene expression profiles were observed under different stimuli, with 76 genes synergistically upregulated under combined hypoxia and inflammation.
• Prostaglandin-endoperoxide synthase 2 (COX-2) was significantly upregulated, leading to increased prostaglandin E2 (PGE2) and driving angiogenesis and inflammation via the COX-2/PGE2/EP2 axis.
• Upregulation of fibrogenic genes (SNAI1, COL1A1) suggested a role for microglia in PDR-associated fibrosis.

Conclusions:

• Microglia are critically involved in the progression of proliferative diabetic retinopathy (PDR).
• The COX-2/PGE2/EP2 signaling pathway mediates microglial-driven angiogenesis and inflammation in PDR.
• Targeting both angiogenic and fibrotic pathways modulated by microglia may offer novel therapeutic strategies for PDR.