Abstract
Purpose :
Although inflammation plays a role in diabetes, the impact of impaired diabetic immune responses on autoimmune disease development remains unclear. We previously found that experimental autoimmune uveoretinitis (EAU) is suppressed in Ins2Akita (Akita) mice, a type 1 diabetes model. Here, we investigate whether EAU suppression also occurs in streptozotocin (STZ)-induced diabetic mice and explore the underlying retinal changes using single-cell RNA sequencing (scRNA-seq).
Methods :
EAU was induced in intact C57BL/6 mice (WT) and STZ mice with human IRBP 1-20 peptide. On day 21 post-immunization, splenocytes were collected for flow cytometry analysis, and retinas were employed for scRNA-seq analysis. After acquiring scRNA-seq data, t-SNE, clustering, differentially expressed gene (DEG) analysis, and Gene Ontology (GO) analysis were performed.
Results :
STZ-EAU mice exhibited suppressed EAU scores compared to WT-EAU mice across clinical, pathological, and OCT evaluations. Flow cytometry revealed decreased Th1 cell populations in STZ-EAU compared to WT-EAU mice, but no significant differences in Th17 or Treg cells. Notably, scRNA-seq analysis showed a marked decrease in microglial cell numbers in STZ-EAU compared to WT-EAU. Among retinal microglia, MHC molecules, CD74, and CCL5 genes were identified as the top downregulated DEGs in STZ-EAU. Additionally, "Antigen presentation," "Response to type II IFN," and "GM-CSF signaling pathway" were downregulated GO terms and pathways in the STZ-EAU/WT-EAU comparison. Furthermore, STZ-EAU mice displayed reduced gene expression of M1 markers (CD86, COX2, CCL2) compared to WT-EAU mice and M2 markers (CD206, P2RY12, CX3CR1, TREM2) were upregulated. However, there were no downregulated M1 marker genes in STZ-EAU compared to WT. In M2 marker genes, only CD206 showed upregulation in STZ-EAU compared to WT, suggesting a potential in the microglial phenotype.
Conclusions :
Our study indicated that EAU was inhibited in STZ diabetic mice, that was not only due to impaired microglial activation, but also suggested the involvement of an immune suppressive mechanism mediated by CD206 gene expression in microglia.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.