Resilience to Diabetic Retinopathy (RDR) Is Associated with a Pre-Retinopathy Transcriptional Program Induced by...

The purpose of this project was to define gene expression changes associated with the acquisition and loss of resilience to diabetic retinopathy (RDR) in individual retinal cell types. A non-immune form of type 1 diabetes mellitus (DM) was induced by injecting male C57Bl6J mice with streptozotocin. Single-cell RNA sequencing was performed on retinas from mice that experienced DM for 5 or 15 days, along with retinas from age-matched, non-DM mice. The resulting data sets were analyzed to identify DM-associated differentially expressed genes and pathway enrichments after each duration of DM. We observed that acquisition of RDR, previously shown to arise after 5 days of DM was linked to altered expression of genes in a subset of retinal cells, mainly Müller cells. Pathway analysis indicated enhancement of numerous modes of protection, including reinforced neurovascular and structural homeostasis through phagocytosis, integrin signaling, and interferon-mediated defense. After 15 days of DM, when we previously showed that RDR is waning this pro-protection surge in gene expression subsided. We conclude that a duration of DM that is too short to cause diabetic retinopathy (DR) nonetheless evoked a profound change in the gene expression profile within a subset of retinal cell types. The nature and timing of this molecular shift indicated that it was not the preamble to DM-related damage that eventually develops. Rather, DM engaged numerous defense programs within Müller cells. The temporal alignment between RDR and activation of Müller cell-based defense provides a molecular foundation for the retina's transient ability to remain healthy in the face of DM.