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Updated: Jul 3, 2026
Digestion of Whole Mouse Eyes for Multi-Parameter Flow Cytometric Analysis of Mononuclear Phagocytes
Published on: June 17, 2020
Infiltrating monocytes augment alternative complement activation and exacerbate inherited retinal degeneration in a
Wenxin Ma1, Quyan Zhang1, Pinghu Liu2
1Retinal Neurophysiology Section.
Abstract:
In retinal degenerative disease, microglia and macrophages accumulate at sites of pathology and strongly influence disease progression, yet their distinct contributions remain unclear. To define the fate and function of infiltrating monocyte-derived macrophages (MDM) in retinal degeneration, we generated a CCR2-CreER mouse line on the rd10 background to enable precise monocyte-specific tracking and ablation. Infiltrating monocytes rapidly downregulated CCR2 and LY6C upon entering the retina and acquired de novo TMEM119 and P2RY12 expression, together with a ramified, microglia-like morphology. Immunohistochemistry and transcriptomic profiling showed that a subset of these cells was cleared by resident microglia. Microglia-monocyte interactions enhanced Müller cell C3 production, whereas activated microglia increased CFB and decreased CFH expression, thereby promoting complement alternative pathway activation. Selective ablation of infiltrating monocytes reduced microglial activation and phagocytosis, suppressed Müller cell C3 expression and complement deposition, lowered proinflammatory cytokine levels, and ultimately ameliorated photoreceptor degeneration. These findings identify infiltrating monocytes as key drivers of immune dysregulation and proinflammation, highlighting them as potential targets for neuroprotective therapy.
Insights
Infiltrating monocytes worsen retinal degeneration by promoting inflammation. Targeting these cells reduced inflammation and protected photoreceptors in a mouse model, offering a potential neuroprotective therapy.
Area of Science:
- Neuroscience
- Immunology
- Ophthalmology
Background:
- Microglia and macrophages accumulate in retinal degenerative diseases, influencing progression.
- Distinct roles of these immune cells in retinal degeneration are not fully understood.
Purpose of the Study:
- To define the fate and function of infiltrating monocyte-derived macrophages (MDM) in retinal degeneration.
- To investigate the impact of these cells on disease progression and explore therapeutic potential.
Main Methods:
- Generated a CCR2-CreER mouse line on the rd10 background for monocyte tracking and ablation.
- Utilized immunohistochemistry and transcriptomic profiling to analyze cell behavior and gene expression.
- Performed selective ablation of infiltrating monocytes to assess functional outcomes.
Main Results:
- Infiltrating monocytes acquired microglia-like characteristics (TMEM119+, P2RY12+) and were partially cleared by resident microglia.
- Microglia-monocyte interactions promoted Müller cell C3 production and alternative complement pathway activation.
- Selective monocyte ablation reduced microglial activation, inflammation, complement deposition, and ameliorated photoreceptor degeneration.
Conclusions:
- Infiltrating monocytes are key drivers of immune dysregulation and inflammation in retinal degeneration.
- Targeting infiltrating monocytes shows therapeutic potential for neuroprotection in retinal degenerative diseases.
