Angiopoietin-like 4 binds neuropilins and cooperates with VEGF to induce diabetic macular edema
Akrit Sodhi, Tao Ma, Deepak Menon, Monika Deshpande, Kathleen Jee, Aumreetam Dinabandhu, Jordan Vancel, Daoyuan Lu, Silvia Montaner
Akrit Sodhi, Tao Ma, Deepak Menon, Monika Deshpande, Kathleen Jee, Aumreetam Dinabandhu, Jordan Vancel, Daoyuan Lu, Silvia Montaner
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Research Article Angiogenesis Ophthalmology

Angiopoietin-like 4 binds neuropilins and cooperates with VEGF to induce diabetic macular edema

Abstract

The majority of patients with diabetic macular edema (DME), the most common cause of vision loss in working-age Americans, do not respond adequately to current therapies targeting VEGFA. Here, we show that expression of angiopoietin-like 4 (ANGPTL4), a HIF-1–regulated gene product, is increased in the eyes of diabetic mice and patients with DME. We observed that ANGPTL4 and VEGF act synergistically to destabilize the retinal vascular barrier. Interestingly, while ANGPTL4 modestly enhanced tyrosine phosphorylation of VEGF receptor 2, promotion of vascular permeability by ANGPTL4 was independent of this receptor. Instead, we found that ANGPTL4 binds directly to neuropilin 1 (NRP1) and NRP2 on endothelial cells (ECs), leading to rapid activation of the RhoA/ROCK signaling pathway and breakdown of EC-EC junctions. Treatment with a soluble fragment of NRP1 (sNRP1) prevented ANGPTL4 from binding to NRP1 and blocked ANGPTL4-induced activation of RhoA as well as EC permeability in vitro and retinal vascular leakage in diabetic animals in vivo. In addition, sNRP1 reduced the stimulation of EC permeability by aqueous fluid from patients with DME. Collectively, these data identify the ANGPTL4/NRP/RhoA pathway as a therapeutic target for the treatment of DME.

Authors

Akrit Sodhi, Tao Ma, Deepak Menon, Monika Deshpande, Kathleen Jee, Aumreetam Dinabandhu, Jordan Vancel, Daoyuan Lu, Silvia Montaner

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Figure 2

ANGPTL4 is increased in diabetic STZ mice and promotes EC permeability in vitro and retinal vascular leakage in vivo.

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ANGPTL4 is increased in diabetic STZ mice and promotes EC permeability i...
(A) ANGPTL4 and VEGF protein levels in control and diabetic STZ animals with sustained hyperglycemia for 3 months. (B) Dose-response curve of the induction of EC permeability by rhANGPTL4 (0.5, 1, 2, 5, 10 μg/mL) or rhVEGFA (1, 5, 10, 50, 100 ng/mL) in HUVECs. (C) Destabilization of the integrity of vascular AJs (β-catenin staining) and TJs (ZO1 staining) of HUVEC or hREC monolayers treated for 6 hours with PBS (control) or rhANGPTL4 (5 μg/mL). Original magnification, ×20. (D and E) Changes in AJ and TJ protein levels upon treatment of HUVEC (D) or hREC (E) with rhANGPTL4 (5 μg/mL), rhcANGPTL4 (5 μg/mL), or rhVEGF (50 ng/mL) for 24 hours. (F and G) Induction of retinal vascular permeability by intraocular injection of C57BL/6J mice (F) or diabetic, STZ mice (G) with 1 μl of PBS, rmVEGFA (100 ng/μl) or rmANGPTL4 (200 ng/μl). Original magnification, ×20. Two-tailed unpaired Student’s t test (A, F, G), 1-way ANOVA (B). **P < 0.01; ***P < 0.001. Experiments were repeated at least 3 times.