BackgroundP21 is one kind of cyclin-dependent kinase inhibitor that can prevent cells from going through the G1/S phase checkpoint and inhibit cell proliferation. Proliferative vitreoretinopathy (PVR) is a proliferative response in the eye. The aim of this study was to determine whether p21Waf1/Cip1 (p21) suppresses the proliferation and migration of retinal pigment epithelial (RPE) cells in vitro and controls PVR development in vivo.MethodsCell cycle analyses and transwell assays were conducted to assess cell proliferation characteristics and the migration ability of RPE cells after transfection with p21. Western blot and reverse-transcription polymerase chain reaction technologies were used to detect the expression of p21, CDK2 and cyclinE in RPE cells and rabbit retinal tissues. The impact of increasing p21 expression on PVR development was conducted by implantation of an adenovirus vector containing rabbit p21 (rAd-p21) in a PVR rabbit model. The prevalence of PVR and retinal detachment was determined by indirect ophthalmoscopy on days 3, 7, 14, and 21 after the injection of rAd-p21 into the vitreous. B scans and hematoxylin-eosin staining were employed to check rabbit retinas on day 21.ResultsCell cycle analyses and transwell assays showed that p21 inhibited the proliferation and migration of RPE cells. Increased expression of p21 was detected in cultured RPE cells and rabbit retinas after transfection with the p21 gene, whereas levels of CDK2 and cyclinE were decreased. The increase in p21 expression effectively suppressed the development of PVR in a rabbit model.ConclusionsThe increase in p21 expression in RPE cells not only inhibits the proliferation and migration of RPE cells in vitro, but also suppresses the development of PVR in vivo, which indicates its therapeutic potential in treating PVR.
Background
Inflammation of RPE cells led to different kinds of eye diseases and affected the normal function of the retina. Furthermore, higher levels of ROCK1 and ROCK2 induced injury of endothelial cells and many inflammatory diseases of the eyes. Ripasudil, which was used for the treatment of glaucoma, was one kind of the inhibitor of ROCK1 and ROCK2, but whether ripasudil could relieve the LPS-induced inflammation and damage of RPE cells was not clear.
Methods
We used LPS to stimulate ARPE-19 cells, the RPE cell line. After that, we detected the levels of ROCK1 and ROCK2 by western-blotting after the stimulation of LPS and treatment of ripasudil. Then luciferase reporter assays were used to confirm the targeting effect of miR-136-5p on ROCK1 and ROCK2. At last, the levels of NLRP3, ASC, caspase1, IL-1β and IL-18 were detected with the western-blotting after the knockdown of miR-136-5p.
Results
The levels of ROCK1, ROCK2 and miR-136-5p in ARPE-19 cells were promoted after the stimulation of LPS. After the treatment of ripasudil, the expression levels of ROCK1, ROCK2 and miR-136-5p were suppressed. The expression of ROCK1 and ROCK2 was targeted and inhibited by the miR-136-5p. The levels of inflammation related proteins NLRP3, ASC, caspase1, IL-1β and IL-18 was also inhibited after the treatment of ripasudil. However, the expression of these proteins was rescued after the knockdown of miR-136-5p.
Conclusion
Ripasudil relieved the inflammatory injury of RPE cells by upregulating miR-136-5p, therefore inhibiting the expression of ROCK1, ROCK2, NLRP3, ASC, caspase1, IL-1β and IL-18.
AbstractHypoxia associated with the high metabolic demand of rods has been implicated in the pathology of age-related macular degeneration (AMD), the most common cause of adult blindness in the developed world. The majority of AMD-associated severe vision loss cases are due to exudative AMD, characterized by neovascularization. To further investigate the causes and histopathology of exudative AMD, we conditionally induced hypoxia in a novel preclinical AMD model (Pde6gcreERT2/+;Vhl−/−) by targeting Vhl and used multimodal imaging and immunohistochemistry to track the development of hypoxia-induced neovascularization. In addition to developing a preclinical model that phenocopies exudative AMD, our studies revealed that the photoreceptor hypoxic response initiates and drives type 3 neovascularization, mainly in the outer retina. Activation of the VHL-HIF1a-VEGF-EPO pathway in the adult retina led to long-term neovascularization, retinal hemorrhages and compromised retinal layers. Our novel preclinical model would accelerate the testing of therapies that use metabolomic approaches to ameliorate AMD.
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