Abstract
Aims/Purpose: Pathological retinal neovascularization (PRNV) in ischemic retinopathies presents a significant clinical challenge. This study investigates the role of bone morphogenetic protein (BMP) signaling via ALK receptors in PRNV, with a focus on epigenetic modifications.Methods: The oxygen‐induced retinopathy (OIR) mouse model was utilized to investigate BMP signaling. Experimental groups included OIR mice treated with Noggin (a BMP inhibitor) or vehicle via ip from postnatal day 12‐16. Additional groups included a combined ALK2 and ALK3 endothelial conditional knockout mice (ALK2/3eKO), subjected to OIR. Capillary degeneration and neovascularization were assessed at postnatal day 17 in flat‐mount retinas using isolectin‐B4 staining. Immunostaining of retinal sections evaluated BMP2, BMP4, and ALK3 localization. In vitro experiments involved human retinal endothelial cells (HRECs) treated with BMP2 (50 ng/ml) or exposed to hypoxia (1% O2) for 48 hours. The impact of BMP2 on vascular endothelial growth factor (VEGF) was assessed through ELISA. MicroRNA (miRNA) expression was analyzed using the GeneChip miRNA 3.0 array. DNA methylation of HRECs was quantified using a colorimetric kit.Results: Immunostaining revealed an upregulation of BMP2, BMP4, and ALK3 expression in retinal vessels. Noggin‐treated and ALK2/3eKO OIR mice exhibited a significant reduction in capillary dropout and neovascularization (p < 0.01). BMP2 treatment of HRECs elevated VEGF production. MiRNA array analysis indicated significant alterations by BMP2 (4%) and hypoxia (5%), including miRNAs linked to VEGF signaling and angiogenesis. Specifically, BMP2 downregulated miR‐4521, miR‐769‐3p, miR‐23b‐5p, miR‐3195, and miR‐6781‐5p, while upregulating miR‐126‐3p, miR‐921, miR‐7515, miR‐29c, and miR‐20b‐5p. Interestingly, BMP2 and hypoxia induced similar effects on certain miRNAs, such as miR‐769‐3p, miR‐23b, and miR‐20b. The DNA methylation assay demonstrated a statistically significant reduction induced by BMP2.Conclusions: BMP/ALK signaling plays a potential role in the pathogenesis of PRNV, possibly mediated through epigenetic modifications. Thereby, targeting BMP/ALK signaling holds a promise to mitigate PRNV in ischemic retinopathies
Published Version
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