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Updated: Jul 15, 2025
A Simple Bioassay for the Evaluation of Vascular Endothelial Growth Factors
Published on: March 15, 2016
The Multi-Kinase Inhibitor RepSox Enforces Barrier Function in the Face of Both VEGF and Cytokines
Lina Lietuvninkas1, Basma Baccouche1, Andrius Kazlauskas1,2
1Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA.
Abstract:
The therapeutic benefit provided by anti-vascular endothelial growth factor (VEGF) for patients with vision-threatening conditions such as diabetic retinopathy (DR) demonstrates the important role of VEGF in this affliction. Cytokines, which can be elevated in the vitreous of patients with DR, promote leakage of retinal blood vessels, and may also contribute to pathology, especially in those patients for whom anti-VEGF does not provide adequate benefit. In this in vitro study using primary human retinal endothelial cells, we compared anti-VEGF with the (transforming growth factor beta) TGFβ receptor inhibitor RepSox (RS) for their ability to enforce barrier function in the face of VEGF, cytokines, and the combination of both. RS was superior to anti-VEGF because it prevented permeability in response to VEGF, cytokines, and their combination, whereas anti-VEGF was effective against VEGF alone. The inhibitory effect of RS was associated with suppression of both agonist-induced pore formation and disorganization of adherens junctions. RS-mediated inhibition of the TGFβ pathway and increased expression of claudin-5 did not adequately explain how RS stabilized the endothelial cell barrier. Finally, RS not only prevented barrier relaxation, but also completely or partially reclosed a barrier relaxed with tumor necrosis factor α (TNF α) or VEGF, respectively. These studies demonstrate that RS stabilized the endothelial barrier in the face of both cytokines and VEGF, and thereby identify RS as a therapeutic that has the potential to overcome permeability driven by multiple agonists that play a role in the pathology of DR.
Insights
RepSox (RS) stabilized retinal endothelial cells against vascular endothelial growth factor (VEGF) and cytokines, unlike anti-VEGF therapies. This suggests RS as a potential treatment for diabetic retinopathy (DR) by targeting multiple pathological pathways.
Area of Science:
- Ophthalmology
- Vascular Biology
- Cell Biology
Background:
- Vascular endothelial growth factor (VEGF) is crucial in diabetic retinopathy (DR) pathogenesis.
- Cytokines also contribute to retinal blood vessel leakage in DR.
- Anti-VEGF therapy is beneficial but not always adequate for DR patients.
Purpose of the Study:
- To compare the efficacy of RepSox (RS), a transforming growth factor beta (TGFβ) receptor inhibitor, with anti-VEGF in maintaining endothelial barrier function.
- To investigate the mechanisms by which RS stabilizes the endothelial barrier.
- To evaluate RS's potential to overcome permeability driven by multiple agonists in DR.
Main Methods:
- In vitro study using primary human retinal endothelial cells.
- Comparison of anti-VEGF and RS in response to VEGF, cytokines, and their combination.
- Assessment of barrier function, pore formation, adherens junction integrity, and claudin-5 expression.
- Evaluation of RS's ability to prevent or reverse barrier relaxation.
Main Results:
- RS was superior to anti-VEGF, preventing permeability induced by VEGF, cytokines, and their combination.
- Anti-VEGF was only effective against VEGF alone.
- RS suppressed agonist-induced pore formation and adherens junction disorganization.
- RS demonstrated the ability to reclose a relaxed endothelial barrier.
Conclusions:
- RepSox (RS) effectively stabilizes the endothelial barrier against both VEGF and cytokines, key factors in diabetic retinopathy (DR).
- RS shows potential as a therapeutic agent to address the complex permeability issues in DR that are not fully resolved by anti-VEGF treatments.
- Further investigation into RS's mechanism, including its effect on TGFβ pathway and claudin-5, is warranted.
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