Systemic exposure to CpG-ODN elicits low-grade inflammation in the retina

Jelena M. Kezic, Paul G. McMenamin

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Abstract

Previous studies have reported that topical exposure to the toll-like receptor (TLR) 9 ligand CpG-ODN causes widespread ocular inflammation, including retinal microglial activation and posterior segment inflammation. Here we sought to determine the effects of systemic exposure to CpG-ODN in the retina and whether this inflammatory response was altered with Cx3cr1 deficiency or hyperglycemia. Male non-diabetic Cx3cr1+/gfp and Cx3cr1gfp/gfp littermates (normoglycemic controls) and Cx3cr1+/gfp Ins2Akita and Cx3cr1gfp/gfp Ins2Akita diabetic mice were injected intraperitoneally with 40 μg CpG-ODN. Immunofluorescence staining was performed 1 week later to assess the expression of MHC Class II and glial fibrillary acidic protein (GFAP), as well as to identify morphological changes to microglia and changes in retinal macrophage cell density. Systemic exposure to CpG-ODN induced the upregulated expression of both GFAP on retinal Müller cells and MHC Class II on the retinal vasculature. Additionally, there was an increased accumulation of macrophages in the subretinal space 1 week after exposure to systemic CpG-ODN as well as characteristic morphological changes to microglia indicative of an activated phenotype. These preliminary studies demonstrate that low-grade inflammatory changes were not enhanced in Cx3cr1-deficient or diabetic mice, indicating that the inflammatory response to systemic CpG-ODN in the retina is unaltered in the context of Cx3cr1 deficiency or prolonged hyperglycemia.

Original languageEnglish
Article number107708
Number of pages7
JournalExperimental Eye Research
Volume186
DOIs
Publication statusPublished - Sep 2019

Keywords

  • CpG-ODN
  • Cxcr1
  • Hyperglycemia
  • microglia
  • Retina
  • Toll-like receptor

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