LRP-1 Pathway Targeted Inhibition of Vascular Abnormalities in the Retina of Diabetic Mice

ABSTRACT

Purpose: The cell surface LDL (low-density lipoprotein) receptor-related protein-1 (LRP-1) is important for lipid transport and several cell signaling processes. Human apolipoprotein E (apoE) is a ligand of LRP-1. We previously reported that a short peptide (apoEdp) mimicking the LRP-1 binding region of apoE prevents hyperglycemia-induced retinal endothelial cell dysfunction in vitro. The in-vivo outcome of apoE-based peptidomimetic inhibition of LRP-1 in the treatment of diabetic retinopathy is unknown.

Methods: Six months after streptozotocin induction of diabetes, male C57Bl/6 mice were intravitreally inoculated with apoEdp in a controlled release formulation. On the 15th day post-apoEdp treatment, mouse retinas were harvested to examine (1) blood–retinal–barrier (BRB) permeability by Evans blue dye, inflammatory leukostasis by concanavalin staining of leukocytes and LRP-1 pathway-related protein expression by Western blot analysis and gelatin zymography.

Results: Intravitreal apoEdp treatment of diabetic mice significantly reduced Evans blue extravasation and the number of adherent leukocytes in the diabetic mouse retinas. ApoEdp treatment inhibited the expression of extracellular matrix (ECM) degrading proteases heparanase and MMP-2, and restores the BRB tight junction proteins occludin and ZO-1. ApoEdp treatment also inhibited Wnt/β-catenin-related expression of pro-inflammatory molecules ICAM-1, HIF-1α, and VEGF through negative regulation by LRP-1.

Conclusion: Intravitreal apoEdp treatment of diabetic mice resulted a significant decrease in retinal vascular abnormalities through downregulation of LRP-1-related ECM protein degradation and Wnt/β-catenin-related pro-angiogenic molecules.

KEYWORDS:

• BRB
• diabetic retinopathy
• ECM
• LRP-1
• Wnt/β-catenin

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Funding

Support is provided in part by grant number 2G12MD007595-06 (PSB) from the National Institute on Minority Health and Health Disparities (NIMHD), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Department of Defense (DoD) grant #W911NF1510059 (TH, PSB), Louis Stokes Louisiana Alliance for Minority Participation (LS-LAMP), National Science Foundation (NSF) Human Resource Development (HRD) award# 1503226 (SM). The contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH, NIGMS, NSF or DoD. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Additional information

Funding

Support is provided in part by grant number 2G12MD007595-06 (PSB) from the National Institute on Minority Health and Health Disparities (NIMHD), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Department of Defense (DoD) grant #W911NF1510059 (TH, PSB), Louis Stokes Louisiana Alliance for Minority Participation (LS-LAMP), National Science Foundation (NSF) Human Resource Development (HRD) award# 1503226 (SM). The contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH, NIGMS, NSF or DoD. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.