Elevated Pressure Changes the Purinergic System of Microglial Cells

Area of Science:

• Neuroscience
• Immunology
• Ophthalmology

Background:

• Glaucoma, a leading cause of blindness, involves retinal ganglion cell degeneration and optic nerve atrophy.
• Microglia reactivity and neuroinflammation are early events in glaucoma pathogenesis.
• The role of the purinergic system in microglial cells during glaucoma is not well understood.

Purpose of the Study:

• To investigate how elevated hydrostatic pressure (EHP), mimicking ocular hypertension, affects the purinergic system in microglial cells.
• To determine changes in extracellular ATP, adenosine, and the expression/activity of related purinergic molecules.

Main Methods:

• Utilized the murine microglial BV-2 cell line exposed to EHP.
• Quantified extracellular ATP and adenosine levels.
• Assessed the expression, density, and activity of key purinergic enzymes, transporters, and receptors (e.g., CD39, equilibrative nucleotide transporter 2, adenosine deaminase, adenosine A1 and A3 receptors).

Main Results:

• EHP increased extracellular ATP and adenosine levels in microglial cells.
• EHP elevated the density of ecto-nucleoside triphosphate diphosphohydrolase 1 (CD39) and decreased equilibrative nucleotide transporter 2 density and adenosine deaminase activity.
• Adenosine A1 receptor expression decreased, while A3 receptor expression remained unchanged; EHP bolstered microglial migration, but not phagocytosis, via ATP and adenosine.

Conclusions:

• The purinergic system in microglia is significantly altered under elevated hydrostatic pressure conditions.
• These findings suggest a role for microglial purinergic signaling in the neuroinflammatory and neurodegenerative processes of glaucoma.
• Further understanding of these mechanisms could reveal new therapeutic targets for glaucoma.