June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Microglia promote amacrine cell loss in a mouse model of early-stage diabetic retinopathy
Author Affiliations & Notes
  • Chas Pfeifer
    Ophthalmology & Visual Sciences, Washington University in St Louis, St Louis, Missouri, United States
  • Andrea Santeford
    Ophthalmology & Visual Sciences, Washington University in St Louis, St Louis, Missouri, United States
  • Wandy L. Beatty
    Molecular Microbiology, Washington University in St Louis, St Louis, Missouri, United States
  • Rajendra S Apte
    Ophthalmology & Visual Sciences, Washington University in St Louis, St Louis, Missouri, United States
  • Footnotes
    Commercial Relationships   Chas Pfeifer None; Andrea Santeford None; Wandy Beatty None; Rajendra Apte None
  • Footnotes
    Support  T32 EY013360
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 2042. doi:
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    • Get Citation

      Chas Pfeifer, Andrea Santeford, Wandy L. Beatty, Rajendra S Apte; Microglia promote amacrine cell loss in a mouse model of early-stage diabetic retinopathy. Invest. Ophthalmol. Vis. Sci. 2023;64(8):2042.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Microglia (MG) activation and inner retinal degeneration are concurrent features of early-stage diabetic retinopathy (DR) in patients and animal models. MG mediate neuronal fate in other models of retinal disease but it remains unclear whether MG contribute to loss of retinal neurons in DR. We tested the hypothesis that MG ablation would preserve neuronal cell types in a streptozotocin-induced (STZ) mouse model of DR.

Methods : Male Cx3cr1YFP-CreER/+; Rosa26DTA/+ mice were given intraperitoneal injections of STZ (150mg/kg) or vehicle. STZ diabetic and non-diabetic littermates were moved to cages with tamoxifen-infused (500mg/kg) or regular chow for 8 weeks to compare control (CTRL), diabetic (STZ), MG-ablated (DTA), and diabetic MG-ablated (STZ DTA) mouse groups. Retina cryo-sections (20µm) from each group (n=5-6) were immunostained for MG, bipolar cells (BPC), ganglion cells (RGC), and two subtypes of amacrine cells (ChAT, vGlut3). Imaris software was used to quantify MG-amacrine contact interactions in STZ and CTRL retinas (n=5-7). Transmission electron microscopy (TEM) was used to examine ultrastructure of STZ and CTRL MG (n=3).

Results : STZ retinas showed significant reductions in BPC (84.93±3.76%; p=.0205), RGC (83.42±3.09%; p=.0141), ChAT (78.13±3.48%; p=.0038), and vGlut3 (75.14±3.87%) staining compared to CTRL. STZ DTA retinas showed significant reductions in BPC (86.70±3.72%; p=.0373) staining compared to CTRL. Reductions in ChAT and vGlut3 staining in STZ DTA retinas were not significantly different from CTRL, but were significantly increased compared to STZ (ChAT, p=.0014; vGlut3, p=.0233). MG significantly increased contact (ChAT; p=.0410, vGlut3; p=.0322) and engulfment of amacrine cell subtypes in STZ retinas compared to CTRL. TEM showed that STZ MG, but not CTRL MG, demonstrated chromatin remodelling, irregular mitochondria, and encircling of compromised amacrine synapses.

Conclusions : Our results support our hypothesis in demonstrating that chronic ablation of retinal microglia preserves neuronal cell types lost during early-stage DR. Further, we show that increased contact and engulfment of amacrine cells by microglia may explain this facet of disease. Future work will be devoted to identifying molecular mechanisms that explain microglia-dependent loss of amacrine cells in early DR.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1: Representative reconstructions of MG-ChAT contacts in CTRL and STZ retinas.

Figure 1: Representative reconstructions of MG-ChAT contacts in CTRL and STZ retinas.

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