Bone Morphogenetic Protein (BMP)4 But Not BMP2 Disrupts the Barrier Integrity of Retinal Pigment Epithelia and Induces Their Migration: A Potential Role in Neovascular Age-Related Macular Degeneration

Ahmed S Ibrahim; Khaled Hussein; Fang Wang; Ming Wan; Nancy Saad; Maamon Essa; Ivana Kim; Akbar Shakoor; Leah A Owen; Margaret M DeAngelis; Mohamed Al-Shabrawey

doi:10.3390/jcm9072293

Bone Morphogenetic Protein (BMP)4 But Not BMP2 Disrupts the Barrier Integrity of Retinal Pigment Epithelia and Induces Their Migration: A Potential Role in Neovascular Age-Related Macular Degeneration

J Clin Med. 2020 Jul 19;9(7):2293. doi: 10.3390/jcm9072293.

Authors

Ahmed S Ibrahim^{1

2}, Khaled Hussein^{3

4}, Fang Wang^{4

5}, Ming Wan^{4

5}, Nancy Saad^{4

6}, Maamon Essa^{4

7}, Ivana Kim⁸, Akbar Shakoor⁹, Leah A Owen⁹, Margaret M DeAngelis^{9

10

11}, Mohamed Al-Shabrawey^{4

12

13

14}

Affiliations

¹ Department of Ophthalmology, Visual, and Anatomical Sciences, Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA.
² Department of Biochemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt.
³ Department of Medicine and Surgery, Oral and Dental Research Division, National Research Centre, Cairo 12622, Egypt.
⁴ Department of Oral Biology and Diagnostic Sciences, Augusta University, Augusta, GA 30912, USA.
⁵ Department of Traditional Chinese Medicine, School of Medicine, Jianghan University, Wuhan 430199, China;.
⁶ Dental school, University of Alberta Canada, Edmonton AB T6G 2R3, Canada.
⁷ Department of Medical Biochemistry, Mansoura Faculty of Medicine, Mansoura University, Mansoura 35516, Egypt.
⁸ Retina Service, Harvard Medical School, Massachusetts Eye and Ear, Boston, MA 02115, USA.
⁹ Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT 84112, USA.
¹⁰ Department of Population Health Sciences, University of Utah School of Medicine; Salt Lake City, UT 84132, USA.
¹¹ Department of Ophthalmology, Jacobs School of Medicine and Biomedical Engineering, University at Buffalo SUNY, and the VA Western New York Healthcare System, Buffalo, NY 14215, USA.
¹² Department of Cellular Biology and Anatomy, Augusta University, GA 30912, USA.
¹³ Department of Ophthalmology and Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA.
¹⁴ Department of Anatomy, Mansoura Faculty of Medicine, Mansoura University-Egypt, Dakahlia Governorate 35516, Egypt.

Abstract

Disruption of retinal pigment epithelial (RPE) barrier integrity and RPE migration are hallmark features in neovascular age-related macular degeneration (nAMD), but the underlying causes and pathophysiology are not completely well-defined. Herein, we aimed to evaluate the effect of bone morphogenetic proteins (BMPs) on the barrier function and migration of RPE. In particular, we investigated the role of BMP2 and BMP4 in these processes as our analysis of RNA-sequencing (seq) data from human donor eyes demonstrated that they are highly differentially expressed BMP members in macular RPE/choroid versus macular retina. We used electrical cell-substrate impedance sensing (ECIS) system to monitor precisely in real time the barrier integrity and migration of ARPE-19 after treatment with various concentrations of BMP2 or BMP4. Immunofluorescence was also used to assess the changes in the expression and the organization of the key tight junction protein, zona occludens (ZO)-1, in ARPE-19 cells under BMP2 or BMP4 treatment. This was followed by measuring the activity of matrix metalloproteinases (MMPs). Finally, RNA-seq and ELISA were used to determine the local and circulating levels of BMP2 and BMP4 in retinas and serum samples from nAMD donors. Our ECIS results showed that BMP4 but not BMP2 decreased the transcellular electrical resistance (TER) of ARPE-19 and increased their migration in comparison with control (vehicle-treated cells). Furthermore, immunofluorescence showed a disorganization of ZO-1 in BMP4-treated ARPE-19 not in BMP2-treated cells or vehicle-treated controls. This effect of BMP4 was associated with significant increases in the activity of MMPs, specifically MMP2. Lastly, these results were corroborated by additional findings that circulating but not local BMP4 levels were significantly higher in nAMD donor samples compared to controls. Collectively, our results demonstrated unreported effects of BMP4 on inducing RPE dysfunction and suggest that BMP4 but not BMP2 may represent a potential therapeutic target in nAMD.

Keywords: ARPE-19; BMP2; BMP4; age related macular degeneration (AMD); retinal pigment epithelial cells (RPE).

Abstract

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