IFN-gdeficient Ins2^+/- (Akita) mouse is a new model of diabetic retinopathy

Abstract

Purpose : Heterozygous Ins2^+/-(Akita) mice develop pronounced hyperglycemia, and present some histopathological changes in the retina, however, the retinal lesion is mild and not causing proliferative diabetic retinopathy (PDR) observed in human. We have recently indicated that Th2- and Th17-related cytokines augmented in the vitreous of patients with PDR. In IFN-gdeficient (GKO) mice which are unable to promote Th1 immune response, Th cells preferentially differentiate into Th2 and Th17 cells. In this study, we generated GKO x Akita mice by mating Akita mice with GKO mice, and investigated the pathological changes in the retina and the specific immune responses.

Methods : Wild type, GKO, Akita, and GKO x Akita mice were immunized by OVA emulsified with CFA at 7 and 8-week-old. At 9-week-old, blood glucose levels, fundus photography (FP), fluorescein angiography (FA), leukostasis, and histological changes were examined. In addition, mRNA expression of VEGF, ICAM-1 and transcription factors of Th1 (T-bet), Th2 (GATA-3), and Th17 (ROR-γT ) in the retina by quantitative PCR (qPCR), and intracellular production of IL-2, IL-4, IL-10, IL-17, IL-22, and TNFa in CD4⁺splenocytes were analyzed.

Results : Blood glucose levels in GKO x Akita mice were compatible with those of Ins2^Akitamice, which were significantly higher than wild type or GKO mice. Retinal exudative lesions were detected only in GKO x Akita miceby FP which were stained as hyperfluorescences in FA. Dye leakages from retinal vessels and non-perfusion area were also presented. Pathological examination revealed edematous changes of the surface layers of the retina in GKO x AKita mice, which were not observed in other mice. Retinal mRNA expression of VEGF, ICAM-1, GATA-3, and ROR-γT were the highest in GKO x Akita mice, and statistical differences were observed between them. In addition, IL-17⁺ and IL-22⁺ cells were significantly increased in GKO x Akita mice compared with mice of other groups. IL-4⁺ and IL-10⁺ cells were also increased in in GKO x Akita mice, but were compatible with those of GKO mice.

Conclusions : GKO x Akita mice developed severe retinopathy compared with Akita mice, that was suggested to be related to the activation of Th17-mediated immune responses.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.