Sustained hyperglycemia impairs corneal re-epithelialization after alkaline injury through modulation of the ocular surface, systemic Immunity and intestinal microbiome

Abstract

Purpose :
1) To compare corneal re-epithelialization rates, ocular surface and systemic immune response after corneal alkali burn injury between Akita (diabetic) and wild type (WT) mice.
2) To compare gut microbial diversity patterns between diabetic and WT mice at baseline and 72 hours after alkaline burn injury and to correlate this with ocular surface findings.

Methods : Heterozygous Ins2^Akita mice were used as a mouse model of Type I diabetes, with WT C57BI6/J mice serving as controls. Alkaline burn injury was induced on the right eye of mice under general anesthesia. The cornea was examined with slit lamp with fluorescein stain under cobalt blue light. Tear samples were collected using Schirmer’s strip paper to determine ocular surface cytokine secretion by protein microarray assay. T cell profile on the ocular surface, in the peripheral blood and intestine were analyzed by flow cytometry. Intestinal microbiome diversity pattern was characterized using shot gun sequencing technique.

Results : Sustained hyperglycemia was associated with prolonged corneal wound healing after cornea alkali burn injury. Furthermore, diabetic mice had significantly lower tear angiopoietin-2( Ang-2), insulin growth factor-1(IGF-1) and vascular endothelial growth factor A (VEGF-A) levels after injury compared to controls. In the peripheral blood, significantly elevated levels of CD4+ T cells was seen in WT mice at day 3 after injury, but not in Akita mice. Meanwhile, significantly higher levels immature CD4+CD8+ T cells were found on the ocular surface of Akita mice compared to controls after injury. Regarding microbial diversity, Akita mice were found to have higher abundance of microbiota composition as compared to WT mice from the CHAO1 index of alpha diversity at day 3 after the injury.

Conclusions : Diabetic mice have shown significantly impaired corneal wound healing response after injury compared to controls. This is associated with the altered ocular surface immunity in diabetic mice. Baseline and post-injury differences in intestinal microbiome composition and diversity may play a role in the altered immune response in diabetes. The presence of systemic chronic inflammation and immature T cell population on the ocular surface of diabetic mice may lead to attenuated post-injury T cell response in diabetic mice.

This is a 2021 ARVO Annual Meeting abstract.