Authors: Chen Jia, Yang Ying, Su Shu, Zhang Shenglai, Yang Xiaowei, Sang Aimin
DOI: 10.3760/cma.j.cn115989-20240207-00042
Published: 2025 -10 -10
Citation
Chen Jia, Yang Ying, Su Shu, et al. Promotive effect of hypoxia-induced ANGPTL4 expression on experimental choroidal neovascularization[J]. Chin J Exp Ophthalmol, 2025, 43(10):906-914. DOI: 10.3760/cma.j.cn115989-20240207-00042.
ABSTRACT [Download PDF] [View Full Text]
Objective To investigate the role of hypoxia-induced angiopoietin-like protein 4 (ANGPTL4) expression in experimental choroidal neovascularization (CNV).
Methods Twenty-seven SPF male C57BL/6J mice aged 6-8 weeks were selected.Eighteen of the mice were used to establish a laser-induced CNV model.On the 7th day after laser photocoagulation, success of the modeling was verified using optical coherence tomography angiography (OCTA) and fundus fluorescein angiography (FFA). The retinal pigment epithelium (RPE)-choroid-sclera complex was extracted for protein analysis before modeling and on the 3rd and 7th days after modeling.The relative expression levels of ANGPTL4 and vascular endothelial growth factor (VEGF) at different time points were detected by Western blot.Additionally, frozen sections of mouse eyeballs on day 7 after modeling were prepared and the expression and cellular localization of ANGPTL4 were observed by immunofluorescence.RF/6A cells, derived from monkey choroidal retinal endothelial cells, were treated with 200 μmol/L cobalt chloride (CoCl 2) in the culture medium for 0, 3, 6, and 12 hours.RF/6A cells were also divided into a normal control group, a hypoxia group, and a hypoxia+ si-ANGPTL4 group, and cells were transfected with a plasmid containing si-ANGPTL4 sequence.The relative expression levels of ANGPTL4 and VEGF proteins in each group were detected by Western blot, and the differences in tube formation among the groups were observed by tube formation assay.A total of 27 male C57BL/6J mice were randomly divided into CNV group, CNV+ si-NC group, and CNV+ si-ANGPTL4 group, with 9 mice in each group.In the CNV+ si-NC and CNV+ si-ANGPTL4 groups, si-NC and si-ANGPTL4 were respectively injected into the vitreous cavity after the CNV model was established.Fluorescence leakage in mice was observed by FFA, and the length, thickness and area of CNV was observed using OCTA and immunofluorescence staining of choroidal flat mounts.The relative expression levels of ANGPTL4 and VEGF proteins in each group were detected by Western blot.All animal experiments were conducted in accordance with ARVO Statement on the Use of Animals in Ophthalmic and Vision Research.The experimental protocol was approved by the Affiliated Hospital of Nantong University (No.S20220822-902).
Results Before modeling and on the 3rd and 7th days after modeling, the relative expression levels of ANGPTL4 protein were 1.00±0.00, 1.58±0.05, and 1.90±0.04, respectively, and the relative expression levels of VEGF protein were 1.00±0.00, 1.31±0.05, and 1.84±0.04, respectively, with statistically significant overall differences ( F=528.934, 390.424, both P<0.05). Among them, on the 3rd and 7th days after modeling, the relative expression levels of ANGPTL4 and VEGF proteins were significantly higher in CNV group than in the control group (all P<0.05). The tissues of each layer of the retina were clear in the control group, while neovascularization could be seen growing under the retinal neuroepithelial layer in the CNV group.Compared with the control group, ANGPTL4 expression was significantly increased and colocalized with vascular endothelial cells in the CNV group.After CoCl 2 treatment of RF/6A cells for 3, 6, and 12 hours, the relative expression levels of ANGPTL4 and VEGF proteins were higher than at 0 hour, with statistically significant differences (all P<0.05). Compared with the control group, the relative ANGPTL4 protein expression was increased in the hypoxia group and significantly decreased in the hypoxia+ si-ANGPTL4 group, showing statistically significant differences (both P<0.05). The number of tube formations in the control group, hypoxia group, and hypoxia+ si-ANGPTL4 group were 12.67±1.53, 19.64±1.56, and 17.01±1.04, respectively, with a statistically significant overall difference ( F=33.091, P<0.01). The number of tube formations increased in the hypoxia group and hypoxia+ si-ANGPTL4 group compared with the control group, and the number of tube formations decreased in the hypoxia+ si-ANGPTL4 group compared with the hypoxia group, with statistically significant differences (all P<0.05). Relative expression levels of ANGPTL4 and VEGF proteins were significantly lower in the CNV+ si-ANGPTL4 group than those in the CNV group (both P<0.05). The CNV area was significantly lower in the CNV+ si-ANGPTL4 group than in the CNV group and CNV+ si-NC group (both P<0.05).
Conclusions Hypoxia-induced ANGPTL4 promotes experimental CNV formation in vivo and in vitro.Inhibiting ANGPTL4 can reduce CNV formation and leakage.
Authors Info & Affiliations
Chen Jia
Department of Ophthalmology, Affiliated Hospital of Nantong University, Nantong 226001, China
Yang Ying
Department of Ophthalmology, Affiliated Hospital of Nantong University, Nantong 226001, China
Su Shu
Department of Ophthalmology, Affiliated Hospital of Nantong University, Nantong 226001, China
Zhang Shenglai
Department of Ophthalmology, Affiliated Hospital of Nantong University, Nantong 226001, China
Yang Xiaowei
Department of Ophthalmology, Affiliated Hospital of Nantong University, Nantong 226001, China
Sang Aimin
Department of Ophthalmology, Affiliated Hospital of Nantong University, Nantong 226001, China