Abstract
Purpose :
Retinal vascular leakage and leukostasis are important pathologic features in diabetic retinopathy. Retinal vascular leakage is associated with macular edema, a leading cause of vision loss in diabetic patients. Leukostasis causes occlusion of small caliber vessels, worsening capillary nonperfusion. Inflammation plays a central role in the development of both retinal vascular leakage and leukostasis. The nuclear factor of activated T-cells (NFAT) family of transcription factors upregulate inflammatory cytokines and leukocyte adhesion molecules in response to high glucose in vitro. The current study explored the efficacy of NFAT inhibition in preventing retinal inflammation, leukostasis, and vascular leakage in an in vivo model of diabetic retinopathy.
Methods :
The streptozocin-induced (STZ) mouse model was used as the in vivo model of diabetic retinopathy. Hyperglycemia was induced at 4 weeks in C57BL/6J mice. For pharmacologic NFAT inhibition, STZ mice were injected intravitreally with the small molecule NFAT signaling inhibitor INCA-6 (25 uM) or vehicle (0.1% DMSO in PBS). For isoform-specific NFAT inhibition, AAV-shRNAs directed against single NFAT isoforms, or the corresponding AAV-scramble were injected intravitreally. At 10 weeks of hyperglycemia retinas were isolated and retinal expression of cytokines and leukocyte adhesion molecules was quantified by qRT-PCR. Retinal leukostasis was assessed by determining the number of adherent leukocytes within each vessel lumen. Quantitative fluorescein angiography (qFA) and Evans blue dye test (EBD) were performed to measure retinal vascular leakage.
Results :
NFAT inhibition reduced retinal expression of IL6 (Δ= -75%, p<0.05), TNFa (Δ= -78%, p<0.05), VEGF (Δ= -36%, p<0.05), VCAM1 (Δ= -35%, p<0.05), and SELE (Δ= -69%, p<0.05) in the STZ model. Retinal leukostasis decreased by 26% (p<0.05) after NFAT inhibition. NFAT inhibition reduced EBD retinal vascular leakage by 50% (p<0.05) and qFA vascular leakage by 32% (p<0.05). Isoform-specific knock-down of the NFATc2 isoform decreased qFA vascular leakage by 50% (p<0.05).
Conclusions :
NFAT inhibition reduces retinal inflammation, leukostasis, and vascular leakage in the STZ model of diabetic retinopathy. Single NFAT isoform knock-down may be equally effective in preventing retinal vascular pathology.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.