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Pericytes of Indirect Contact Coculture Decrease Integrity of Inner Blood-Retina Barrier Model In Vitro by Upgrading
Tianye Yang1,2, Liang Guo1, Yuan Fang3,4
1Department of Bioengineering, College of Biological Science and Biotechnology, Fuzhou University, Fuzhou, Fujian, China.
Abstract:
Inner blood-retina barrier (iBRB) is primarily formed of retinal microvascular endothelial cells (ECs) with tight junctions, which are surrounded and supported by retinal microvascular pericytes (RMPs) and basement membrane. Pericytes are believed to be critically involved in the physiology and pathology of iBRB. However, the underlying mechanism remains to be fully elucidated. We developed a novel in vitro iBRB model which was composed of primary cultures of rat retinal ECs and RMPs based on Transwell system. We tested the involvement of pericytes in the migration and invasion of ECs, examined the expression and activity of matrix metalloproteinase- (MMP-) 2/MMP-9 in the culture, evaluated the TEER and permeability of iBRB, and assessed the expression of ZO-1, occludin, claudin-5, and VE-cadherin of endothelial junctions. We found that RMPs with indirect contact of ECs can increase the expression of MMP-2 and upgrade the activity of MMP-2/9 in the coculture, which subsequently decreased TJ protein abundance of ZO-1 and occludin in ECs, promoted the migration of ECs, and finally reduced the integrity of iBRB. Taken together, our data show that RMP relative location with ECs is involved in the integrity of iBRB via MMP-2/9 and has important implications for treating diabetic retinopathy and other retinal disorders involving iBRB dysfunction.
Insights
Retinal pericytes influence the inner blood-retina barrier (iBRB) integrity. Pericytes increase matrix metalloproteinase-2/9 (MMP-2/9) activity, reducing tight junction proteins and promoting endothelial cell migration, thus impairing iBRB function.
Area of Science:
- Ophthalmology
- Cell Biology
- Vascular Biology
Background:
- The inner blood-retina barrier (iBRB) is crucial for retinal homeostasis.
- Retinal microvascular pericytes (RMPs) are implicated in iBRB physiology and pathology, but mechanisms are unclear.
Purpose of the Study:
- To investigate the role of RMPs in iBRB integrity using an in vitro model.
- To elucidate the molecular mechanisms by which RMPs affect endothelial cells and iBRB function.
Main Methods:
- Developed a Transwell-based in vitro model of iBRB using primary rat retinal endothelial cells (ECs) and RMPs.
- Assessed EC migration, invasion, matrix metalloproteinase (MMP-2/9) expression and activity, transepithelial electrical resistance (TEER), permeability, and tight junction protein expression (ZO-1, occludin, claudin-5, VE-cadherin).
Main Results:
- Indirect contact with RMPs increased MMP-2 expression and MMP-2/9 activity in cocultures.
- This led to decreased ZO-1 and occludin abundance in ECs.
- RMP presence promoted EC migration and reduced iBRB integrity.
Conclusions:
- RMP proximity to ECs impacts iBRB integrity through MMP-2/9.
- Findings suggest RMP-EC interactions are critical for maintaining iBRB function.
- This has implications for treating retinal disorders like diabetic retinopathy involving iBRB dysfunction.
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