PurposeTo study the role of long non-coding RNA (lncRNA) MALAT1 in transforming growth factor beta 1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells.MethodsARPE-19 cells were cultured and exposed to TGF-β1. The EMT of APRE-19 cells is confirmed by morphological change, as well as the increased expression of alpha-smooth muscle actin (αSMA) and fibronectin, and the down-regulation of E-cadherin and Zona occludin-1(ZO-1) at both mRNA and protein levels. The expression of lncRNA MALAT1 in RPE cells were detected by quantitative real-time PCR. Knockdown of MALAT1 was achieved by transfecting a small interfering RNA (SiRNA). The effect of inhibition of MALAT1 on EMT, migration, proliferation, and TGFβ signalings were observed. MALAT1 expression was also detected in primary RPE cells incubated with proliferative vitreoretinopathy (PVR) vitreous samples.ResultsThe expression of MALAT1 is significantly increased in RPE cells incubated with TGFβ1. MALAT1 silencing attenuates TGFβ1-induced EMT, migration, and proliferation of RPE cells, at least partially through activating Smad2/3 signaling. MALAT1 is also significantly increased in primary RPE cells incubated with PVR vitreous samples.ConclusionLncRNA MALAT1 is involved in TGFβ1-induced EMT of human RPE cells and provides new understandings for the pathogenesis of PVR.

Exosomes have recently emerged as a pivotal mediator of many physiological and pathological processes. However, the role of exosomes in proliferative vitreoretinopathy (PVR) has not been reported. In this study, we aimed to investigate the role of exosomes in PVR. Transforming growth factor beta 2 (TGFß‐2) was used to induce epithelial‐mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells, as an in vitro model of PVR. Exosomes from normal and EMTed RPE cells were extracted and identified. We incubated extracted exosomes with recipient RPE cells, and co‐cultured EMTed RPE cells and recipient RPE cells in the presence of the exosome inhibitor GW4869. Both experiments suggested that there are further EMT‐promoting effects of exosomes from EMTed RPE cells. MicroRNA sequencing was also performed to identify the miRNA profiles in exosomes from both groups. We identified 34 differentially expressed exosomal miRNAs (P <. 05). Importantly, miR‐543 was found in exosomes from EMTed RPE cells, and miR‐543‐enriched exosomes significantly induced the EMT of recipient RPE cells. Our study demonstrates that exosomal miRNA is differentially expressed in RPE cells during EMT and that these exosomal miRNAs may play pivotal roles in EMT induction. Our results highlight the importance of exosomes as cellular communicators within the microenvironment of PVR.

The major pathogenesis of proliferative vitreoretinopathy (PVR) is that retinal pigment epithelial (RPE) cells undergo epithelial‐mesenchymal transition (EMT) because of disordered growth factors, such as TGF‐β, in the vitreous humor. Bone morphogenetic proteins (BMPs) are pluripotent growth factors. In this study, we identified the antifibrotic activity of BMP7 in a PVR model both in vivo and in vitro. BMP7 expression was confirmed on the PVR proliferative membranes. BMP7 was down‐regulated in the PVR vitreous humor and TGF‐β–induced RPE cell EMT. In the in vivo studies, BMP7 injection attenuated PVR progression in the eyes of the rabbit model. Additionally, BMP7 treatment maintained RPE cell phenotypes and relieved TGF‐β2–induced EMT, migration, and gel contraction in vitro. BMP7 inhibited the TGF‐β2–induced up‐regulation of fibronectin and α–smooth muscle actin and the down‐regulation of E‐cadherin and zona occludens‐1 by balancing the TGF‐β2/Smad2/3 and BMP7/Smad1/5/9 pathways. These findings provide direct evidence of the ability of BMP7 in PVR inhibition and the potential of BMP7 for use in PVR therapeutic intervention.—Yao, H., Ge, T., Zhang, Y., Li, M., Yang, S., Li, H., Wang, F. BMP7 antagonizes proliferative vitreoretinopathy through retinal pigment epithelial fibrosis in vivo and in vitro. FASEB J. 33, 3212–3224 (2019). http://www.fasebj.org