Ocular hypertension suppresses homeostatic gene expression in optic nerve head microglia of DBA/2 J mice

Abstract

Glaucoma is the leading cause of irreversible vision loss. Ocular hypertension is a major risk factor for glaucoma and recent work has demonstrated critical early neuroinflammatory insults occur in the optic nerve head following ocular hypertension. Microglia and infiltrating monocytes are likely candidates to drive these neuroinflammatory insults. However, the exact molecular identity / transcriptomic profile of microglia following ocular hypertensive insults is unknown. To elucidate the molecular identity of microglia after long-term exposure to ocular hypertension, we used a mouse model of glaucoma (DBA/2 J). We performed RNA-sequencing of microglia mRNA from the optic nerve head at a time point following ocular hypertensive insults, but preceding detectable neurodegeneration (with microglia identified as being CD45 lo /CD11b + /CD11c −). Furthermore, RNA-sequencing was performed on optic nerve head microglia from mice treated with radiation therapy, a potent therapy preventing neuroinflammatory insults. Transcriptomic profiling of optic nerve head microglia mRNA identifies metabolic priming with marked changes in mitochondrial gene expression, and changes to phagocytosis, inflammatory, and sensome pathways. The data predict that many functions of microglia that help maintain tissue homeostasis are affected. Comparative analysis of these data with data from previously published whole optic nerve head tissue or monocyte-only samples from DBA/2 J mice demonstrate that many of the neuroinflammatory signatures in these data sets arise from infiltrating monocytes and not reactive microglia. Finally, our data demonstrate that prophylactic radiation therapy of DBA/2 J mice potently abolishes these microglia metabolic transcriptomic changes at the same time points. Together, our data provide a unique resource for the community to help drive further hypothesis generation and testing in glaucoma.

GLP-1 Receptor Agonist NLY01 Reduces Retinal Inflammation and Neuron Death Secondary to Ocular Hypertension

“…Transcriptomic data from the DBA/2J mouse model of glaucoma suggest that early inflammation is driven by CD11b + CD11c + cells, while CD11b + CD11c − cells initially adopt an anti-inflammatory pattern of gene expression ( Tribble et al, 2020a ; Williams et al, 2019 ). Our results support this finding by demonstrating that CD11b + CD11c + cells upregulated IL-1α, TNF-α, and C1q expression prior to contribution from CD11b + CD11c − cells.…”

“…Results suggest that CD11b + CD11c + cells are early contributors to A1 astrocyte formation following IOP elevation (eIOP). Transcriptomic data from fluorescence-activated cell sorting (FACS)-isolated CD11b + CD11c + retinal cells in the DBA/2J mouse model of glaucoma demonstrate that this population is enriched for infiltrating macrophages compared to other blood-borne immune cells and resident microglia ( Tribble et al, 2020a ). It should be noted that the embryonic origin of the CD11b + CD11c + cell population has not been conclusively demonstrated, and these cells could therefore represent resident retinal microglia that have undergone a state change, infiltrating macrophages, or a mixture of both.…”

Complement peptide C3a receptor 1 promotes optic nerve degeneration in DBA/2J mice

“…ONH microglia and infiltrating monocytes express C3ar1 at high levels, while RGCs express C3ar1 at a lower level (Fig. 3d, [55,56]). Thus, C3ar1 deficiency in microglia and monocytes may affect their function or number in the ONH of ocular hypertensive eyes based on these expression data.…”

The Interaction Between Microglia and Macroglia in Glaucoma

“…For example, in chronic hereditary glaucoma model DBA/2J mice, the aggregation, activation, and redistribution of microglia can be detected before RGC injury (Bosco et al, 2011). In DBA/2 J mice, the transcriptome of ONH microglia changes significantly in the metabolic, phagocytosis, inflammatory, and sensome pathways (Tribble et al, 2020). Among these, microglial surveillance and phagocytosis are downregulated, whereas metabolism-related transcripts are upregulated.…”