BACKGROUND: Retinal capillary basement membrane thickening is closely associated with the development of vascular lesions in diabetic retinopathy. Thickened capillary basement membrane can compromise blood-retinal-barrier (BRB) characteristics and contribute to retinal vascular permeability, a significant clinical manifestation of diabetic retinopathy. We have previously shown that high glucose (HG) increases the expression and activity of lysyl oxidase (LOX), a crosslinking enzyme, in retinal endothelial cells. Additionally, concomitant with overexpression of LOX, increased vascular permeability was observed in diabetic rat retinas. However, it is unknown whether decreasing LOX overexpression may have protective effects against development of retinal vascular lesions associated with diabetic retinopathy.
OBJECTIVE: To investigate whether reducing LOX level protects against diabetes-induced development of retinal vascular lesions characteristic of diabetic retinopathy
METHODS: In Experiment 1, wild type (WT) control mice, streptozotocin (STZ)-induced diabetic mice, LOX heterozygous knockout (LOX +/-) mice, and STZ-induced diabetic LOX +/- mice were used in the study. In Experiment 2, WT rats, diabetic rats, and diabetic rats intravitreally injected with LOX short interfering RNA (siRNA), or scrambled siRNA as control, were used in the study. 1 month after the onset of diabetes, intravitreal injections were initiated at monthly intervals for up to 3 times. At the end of the study, retinas were assessed for LOX protein level by Western Blot (WB) analysis, and retinal capillary networks were assessed for the number of acellular capillaries (AC) and pericyte loss (PL). Vascular leakage was analyzed by measuring the extravasation of FITC-dextran in retinal capillaries after tail vein injection of FITC-Dextran.
RESULTS: A significant increase in LOX expression was detected in the diabetic retinas compared to those of the WT control retinas while a significant decrease in LOX expression was observed in the diabetic LOX +/- retinas and in the diabetic retinas injected with LOX siRNA. Importantly, when diabetes-induced LOX overexpression was reduced, retinal vascular cell loss and vascular leakage were ameliorated.
CONCLUSION: Decreasing diabetes-induced LOX overexpression may have protective effects against the development of vascular lesions characteristic of diabetic retinopathy. Therefore, LOX overexpression may be a potential target in preventing retinal vascular cell loss and excess permeability associated with diabetic retinopathy.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/36590 |
| Date | 13 June 2019 |
| Creators | Kim, Dongjoon |
| Contributors | Roy, Sayon, Deeney, Jude |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Rights | Attribution-NonCommercial 4.0 International, http://creativecommons.org/licenses/by-nc/4.0/ |
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