TY - JOUR
T1 - Decreased lysyl oxidase level protects against development of retinal vascular lesions in diabetic retinopathy
AU - Kim, Dongjoon
AU - Mecham, Robert P.
AU - Nguyen, Ngan Ha
AU - Roy, Sayon
N1 - Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2019/7
Y1 - 2019/7
N2 - Retinal capillary basement membrane (BM) thickening is closely associated with the development of vascular lesions in diabetic retinopathy. Thickened capillary BM can compromise blood-retinal-barrier characteristics and contribute to retinal vascular permeability, a significant clinical manifestation of diabetic retinopathy. We have previously shown that high glucose 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 in diabetes. To investigate whether reduced LOX level protects against diabetes-induced development of retinal vascular lesions characteristic of diabetic retinopathy, four groups of mice: wild type (WT) control mice, streptozotocin (STZ)-induced diabetic mice, LOX +/− mice, and STZ-induced diabetic LOX +/− mice were used for this study. Diabetes was maintained for 16 weeks; at the end of the study, retinas were assessed for LOX protein level by Western Blot (WB) analysis, and retinal capillary networks were isolated using retinal trypsin digestion and stained with hematoxylin and periodic acid Schiff to identify the number of acellular capillaries (AC) and pericyte loss (PL). In parallel, TUNEL assay was performed on retinal trypsin digests (RTDs) to detect cells undergoing apoptosis in the retinal capillary networks. Retinal vascular permeability was analyzed following FITC-dextran injection in retinal whole mounts. A significant increase in LOX expression was detected in the diabetic retinas compared to those of the WT control retinas, and as expected, a significant decrease in LOX expression in the diabetic LOX +/− retinas was observed compared to those of the diabetic retinas. RTD images showed significantly increased AC and PL counts in the retinas of diabetic mice compared to those of the WT control mice. Importantly, the number of AC and PL was significantly decreased, as was retinal vascular permeability in the retinas of the diabetic LOX +/− mice compared to those of the diabetic mice. Results suggest that 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.
AB - Retinal capillary basement membrane (BM) thickening is closely associated with the development of vascular lesions in diabetic retinopathy. Thickened capillary BM can compromise blood-retinal-barrier characteristics and contribute to retinal vascular permeability, a significant clinical manifestation of diabetic retinopathy. We have previously shown that high glucose 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 in diabetes. To investigate whether reduced LOX level protects against diabetes-induced development of retinal vascular lesions characteristic of diabetic retinopathy, four groups of mice: wild type (WT) control mice, streptozotocin (STZ)-induced diabetic mice, LOX +/− mice, and STZ-induced diabetic LOX +/− mice were used for this study. Diabetes was maintained for 16 weeks; at the end of the study, retinas were assessed for LOX protein level by Western Blot (WB) analysis, and retinal capillary networks were isolated using retinal trypsin digestion and stained with hematoxylin and periodic acid Schiff to identify the number of acellular capillaries (AC) and pericyte loss (PL). In parallel, TUNEL assay was performed on retinal trypsin digests (RTDs) to detect cells undergoing apoptosis in the retinal capillary networks. Retinal vascular permeability was analyzed following FITC-dextran injection in retinal whole mounts. A significant increase in LOX expression was detected in the diabetic retinas compared to those of the WT control retinas, and as expected, a significant decrease in LOX expression in the diabetic LOX +/− retinas was observed compared to those of the diabetic retinas. RTD images showed significantly increased AC and PL counts in the retinas of diabetic mice compared to those of the WT control mice. Importantly, the number of AC and PL was significantly decreased, as was retinal vascular permeability in the retinas of the diabetic LOX +/− mice compared to those of the diabetic mice. Results suggest that 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.
KW - AKT
KW - Apoptosis
KW - Lysyl oxidase
KW - Vascular permeability
UR - http://www.scopus.com/inward/record.url?scp=85064969296&partnerID=8YFLogxK
U2 - 10.1016/j.exer.2019.04.019
DO - 10.1016/j.exer.2019.04.019
M3 - Article
C2 - 31022398
AN - SCOPUS:85064969296
SN - 0014-4835
VL - 184
SP - 221
EP - 226
JO - Experimental eye research
JF - Experimental eye research
ER -