Retina

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Chan CSY, Lonfat N, Zhao R, Davis AE, Li L, Wu M-R, Lin C-H, Ji Z, Cepko CL, Wang S. Cell type- and stage-specific expression of Otx2 is regulated by multiple transcription factors and -regulatory modules in the retina. Development 2020;147(14)Abstract
Transcription factors (TFs) are often used repeatedly during development and homeostasis to control distinct processes in the same and/or different cellular contexts. Considering the limited number of TFs in the genome and the tremendous number of events that need to be regulated, re-use of TFs is necessary. We analyzed how the expression of the homeobox TF, orthodenticle homeobox 2 (Otx2), is regulated in a cell type- and stage-specific manner during development in the mouse retina. We identified seven -regulatory modules (CRMs), among which the O5, O7 and O9 CRMs mark three distinct cellular contexts of Otx2 expression. We discovered that Otx2, Crx and Sox2, which are well-known TFs regulating retinal development, bind to and activate the O5, O7 or O9 CRMs, respectively. The chromatin status of these three CRMs was found to be distinct in different retinal cell types and at different stages. We conclude that retinal cells use a cohort of TFs with different expression patterns and multiple CRMs with different chromatin configurations to regulate the expression of Otx2 precisely.
Chantarasorn Y, Oellers P, Eliott D. Choroidal Thickness Is Associated with Delayed Subretinal Fluid Absorption after Rhegmatogenous Retinal Detachment Surgery. Ophthalmol Retina 2019;3(11):947-955.Abstract
PURPOSE: To investigate the association between choroidal thickness and persistent subretinal fluid (PSF) after surgery for recent-onset rhegmatogenous retinal detachment (RRD). DESIGN: Case-control study. PARTICIPANTS: Fourteen eyes with macula-off RRD (with fovea on and off) that achieved retinal reattachment on funduscopy and demonstrated PSF after surgery (PSF group) were compared with 62 eyes with macula-off RRD (with fovea on and off) that did not demonstrate PSF after surgery (non-PSF group). METHODS: The diagnosis of PSF was made by the detection of subretinal fluid pockets on OCT beyond 6 weeks after surgery. Covariates included baseline demographics, duration of RRD, area of RRD, foveal status, method of subretinal fluid drainage, retinal pigment epithelium (RPE) changes, and choroidal thickness in both eyes. Multivariate regression analysis was performed by adding gender, age, and pathologic myopia into the model. The secondary outcomes included postoperative vision and time to resolution of PSF. MAIN OUTCOME MEASURES: Subfoveal choroidal thickness in affected eyes, measured by enhanced depth imaging OCT images. RESULTS: The percentage of eyes that underwent vitrectomy, scleral buckle surgery, and pneumatic retinopexy were 71.4%, 14.3%, and 14.3% in the PSF group, respectively, and 87.1%, 11.3%, and 1.6% in the non-PSF group, respectively. Eyes with PSF showed significantly thicker subfoveal choroid than eyes without PSF (305±61 μm vs. 200±70 μm, respectively; adjusted difference, 78.6±19.1 μm; 95% confidence interval [CI], 40.3-116.8 μm; P < 0.001). The PSF group demonstrated a greater proportion of RPE changes in fellow eyes (30.8% vs. 1.7%; P = 0.03) and significantly worse best-corrected visual acuity at the 12-month follow-up (P = 0.03). Multiple logistic regression analysis revealed that choroidal thickness of 280 μm or more was a significant factor associated with the presence of PSF (adjusted odds ratio [AOR], 13.4; 95% CI, 3.1-34.7 [P = 0.001]. CONCLUSIONS: Persistent subretinal fluid is associated with increased subfoveal choroidal thickness in surgical and fellow eyes and with RPE changes in the fellow eye. This indicates that PSF likely belongs to the pachychoroid spectrum. In affected eyes, PSF tends to persist for more than 1 year and results in delayed visual recovery.
Chee YE, Eliott D. The Role of Vitrectomy in the Management of Fungal Endophthalmitis. Semin Ophthalmol 2017;32(1):29-35.Abstract

Fungal endophthalmitis is an important cause of vision loss worldwide with a large body of literature describing the treatment of the disease. The evidence supporting the use of pars plana vitrectomy in the management of fungal endophthalmitis is largely comprised of case reports and case series and demonstrates the important role of vitrectomy surgery. Vitrectomy can improve the likelihood of establishing the diagnosis, enhance the treatment of infection by removing fungal elements in the vitreous, aid in the removal of other inoculated intraocular structures, and is an important tool in the management of vision-threatening post-infectious sequelae like retinal detachment and epiretinal membrane.

Chen J, Michan S, Juan AM, Hurst CG, Hatton CJ, Pei DT, Joyal J-S, Evans LP, Cui Z, Stahl A, Sapieha P, Sinclair DA, Smith LEH. Neuronal sirtuin1 mediates retinal vascular regeneration in oxygen-induced ischemic retinopathy. Angiogenesis 2013;16(4):985-92.Abstract
Regeneration of blood vessels in ischemic neuronal tissue is critical to reduce tissue damage in diseases. In proliferative retinopathy, initial vessel loss leads to retinal ischemia, which can induce either regrowth of vessels to restore normal metabolism and minimize damage, or progress to hypoxia-induced sight-threatening pathologic vaso-proliferation. It is not well understood how retinal neurons mediate regeneration of vascular growth in response to ischemic insults. In this study we aim to investigate the potential role of Sirtuin 1 (Sirt1), a metabolically-regulated protein deacetylase, in mediating the response of ischemic neurons to regulate vascular regrowth in a mouse model of oxygen-induced ischemic retinopathy (OIR). We found that Sirt1 is highly induced in the avascular ischemic retina in OIR. Conditional depletion of neuronal Sirt1 leads to significantly decreased retinal vascular regeneration into the avascular zone and increased hypoxia-induced pathologic vascular growth. This effect is likely independent of PGC-1α, a known Sirt1 target, as absence of PGC-1α in knockout mice does not impact vascular growth in retinopathy. We found that neuronal Sirt1 controls vascular regrowth in part through modulating deacetylation and stability of hypoxia-induced factor 1α and 2α, and thereby modulating expression of angiogenic factors. These results indicate that ischemic neurons induce Sirt1 to promote revascularization into ischemic neuronal areas, suggesting a novel role of neuronal Sirt1 in mediating vascular regeneration in ischemic conditions, with potential implications beyond retinopathy.
Chen ZJ, Lu SY, Rong SS, Ho M, Ng DS-C, Chen H, Gong B, Yam JC, Young AL, Brelen M, Tham CC, Pang CP, Chen LJ. Genetic associations of central serous chorioretinopathy: a systematic review and meta-analysis. Br J Ophthalmol 2021;Abstract
AIMS: To identify single-nucleotide polymorphisms (SNPs) associated with central serous chorioretinopathy (CSCR) by a systematic review and meta-analysis, and to compare the association profiles between CSCR, neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV). METHODS: We searched the EMBASE, PubMed and Web of Science for genetic studies of CSCR from the starting dates of the databases to 12 September 2020. We then performed meta-analyses on all SNPs reported by more than two studies and calculated the pooled OR and 95% CIs. We also conducted sensitivity analysis and adopted the funnel plot to assess potential publication bias. RESULTS: Totally 415 publications were reviewed, among them 10 were eligible for meta-analysis. We found 10 SNPs that have been reported at least twice. Meta-analysis and sensitivity analysis confirmed significant associations between CSCR and six SNPs in three genes, namely age-related maculopathy susceptibility 2 (ARMS2) (rs10490924, OR=1.37; p=0.00064), complement factor H (CFH) (rs800292, OR=1.44; p=7.80×10-5; rs1061170, OR=1.34; p=0.0028; rs1329428, OR=1.40; p=0.012; and rs2284664, OR=1.36; p=0.0089) and tumour necrosis factor receptor superfamily, member 10a (TNFRSF10A) (rs13278062, OR=1.34; p=1.44×10-15). Among them, only TNFRSF10A rs13278062 showed the same trend of effect on CSCR, nAMD and PCV, while the SNPs in ARMS2 and CFH showed opposite trends in the SNP associations. CONCLUSIONS: This study confirmed the associations of ARMS2, CFH and TNFRSF10A with CSCR, and revealed that ARMS2, CFH and TNFRSF10A may affect different phenotypic expressions of CSCR, nAMD and PCV.
Chen L, Kim IK, Lane AM, Gauthier D, Munzenrider JE, Gragoudas ES, Miller JW. Proton beam irradiation for non-AMD CNV: 2-year results of a randomised clinical trial. Br J Ophthalmol 2014;98(9):1212-7.Abstract
AIMS: To evaluate safety and visual outcomes after proton beam irradiation (PBI) therapy for subfoveal choroidal neovascularisation (CNV) secondary to causes other than age-related macular degeneration (AMD). METHODS: This study is a prospective, unmasked and randomised clinical trial using two dosage regimens, conducted in the Massachusetts Eye and Ear Infirmary. The study included 46 patients with CNV secondary to non-AMD and best-corrected visual acuity of 20/320 or better. Patients were randomly assigned to receive 16 or 24 cobalt gray equivalents (CGE) of PBI in two equal fractions. Complete ophthalmological examinations, fundus photography and fluorescein angiography were performed at baseline and 6, 12, 18 and 24 months after treatment. RESULTS: At 1 year after treatment, 82% and 72% lost fewer than 1.5 lines of vision in the 16 CGE and in 24 CGE groups, respectively. At 2 years after therapy, 77% in the lower dose group and 64% in the higher dose group lost fewer than 1.5 lines of vision. Mild radiation complications such as radiation vasculopathy developed in 17.6% of patients. CONCLUSIONS: PBI is a safe and efficacious treatment for subfoveal CNV not due to AMD. The data with respect to visual outcomes and radiation complications trend in favour of the 16 CGE group, although differences do not reach statistical significance. PBI may be considered as an alternative to current therapies.
Chen J, Stahl A, Krah NM, Seaward MR, Joyal J-S, Juan AM, Hatton CJ, Aderman CM, Dennison RJ, Willett KL, Sapieha P, Smith LEH. Retinal expression of Wnt-pathway mediated genes in low-density lipoprotein receptor-related protein 5 (Lrp5) knockout mice. PLoS One 2012;7(1):e30203.Abstract
Mutations in low-density lipoprotein receptor-related protein 5 (Lrp5) impair retinal angiogenesis in patients with familial exudative vitreoretinopathy (FEVR), a rare type of blinding vascular eye disease. The defective retinal vasculature phenotype in human FEVR patients is recapitulated in Lrp5 knockout (Lrp5(-/-)) mouse with delayed and incomplete development of retinal vessels. In this study we examined gene expression changes in the developing Lrp5(-/-) mouse retina to gain insight into the molecular mechanisms that underlie the pathology of FEVR in humans. Gene expression levels were assessed with an Illumina microarray on total RNA from Lrp5(-/-) and WT retinas isolated on postnatal day (P) 8. Regulated genes were confirmed using RT-qPCR analysis. Consistent with a role in vascular development, we identified expression changes in genes involved in cell-cell adhesion, blood vessel morphogenesis and membrane transport in Lrp5(-/-) retina compared to WT retina. In particular, tight junction protein claudin5 and amino acid transporter slc38a5 are both highly down-regulated in Lrp5(-/-) retina. Similarly, several Wnt ligands including Wnt7b show decreased expression levels. Plasmalemma vesicle associated protein (plvap), an endothelial permeability marker, in contrast, is up-regulated consistent with increased permeability in Lrp5(-/-) retinas. Together these data suggest that Lrp5 regulates multiple groups of genes that influence retinal angiogenesis and may contribute to the pathogenesis of FEVR.
Chen T-C, She P-Y, Chen DF, Lu J-H, Yang C-H, Huang D-S, Chen P-Y, Lu C-Y, Cho K-S, Chen H-F, Su W-F. Polybenzyl Glutamate Biocompatible Scaffold Promotes the Efficiency of Retinal Differentiation toward Retinal Ganglion Cell Lineage from Human-Induced Pluripotent Stem Cells. Int J Mol Sci 2019;20(1)Abstract
Optic neuropathy is one of the leading causes of irreversible blindness caused by retinal ganglion cell (RGC) degeneration. The development of induced pluripotent stem cell (iPSC)-based therapy opens a therapeutic window for RGC degeneration, and tissue engineering may further promote the efficiency of differentiation process of iPSCs. The present study was designed to evaluate the effects of a novel biomimetic polybenzyl glutamate (PBG) scaffold on culturing iPSC-derived RGC progenitors. The iPSC-derived neural spheres cultured on PBG scaffold increased the differentiated retinal neurons and promoted the neurite outgrowth in the RGC progenitor layer. Additionally, iPSCs cultured on PBG scaffold formed the organoid-like structures compared to that of iPSCs cultured on cover glass within the same culture period. With RNA-seq, we found that cells of the PBG group were differentiated toward retinal lineage and may be related to the glutamate signaling pathway. Further ontological analysis and the gene network analysis showed that the differentially expressed genes between cells of the PBG group and the control group were mainly associated with neuronal differentiation, neuronal maturation, and more specifically, retinal differentiation and maturation. The novel electrospinning PBG scaffold is beneficial for culturing iPSC-derived RGC progenitors as well as retinal organoids. Cells cultured on PBG scaffold differentiate effectively and shorten the process of RGC differentiation compared to that of cells cultured on coverslip. The new culture system may be helpful in future disease modeling, pharmacological screening, autologous transplantation, as well as narrowing the gap to clinical application.
Chen N, Hu Z, Yang Y, Han H, Lei H. Inactive Cas9 blocks vitreous-induced expression of Mdm2 and proliferation and survival of retinal pigment epithelial cells. Exp Eye Res 2019;186:107716.Abstract
Mouse double minute (MDM)2 single nucleotide polymorphism (SNP) 309G allele in the second promoter of MDM2 enhances vitreous-induced expression of Mdm2 and degradation of the tumor suppressor protein p53. This MDM2 contributes to certain cancer development and experimental proliferative vitreoretinopathy. The goal of this study is to discover a novel strategy to only block vitreous-induced expression of Mdm2 for preventing vitreous-induced cell proliferation and survival and thus find a potential novel strategy to treat proliferation-related diseases. We created two mutations (D10A and H840A) in Streptococcus pyogenes (Sp)Cas9 within the nuclease domains (RuvC1 and HNH, respectively) to render this SpCas9 nuclease dead named as dCas9 in a lentiCRISPR v2 vector. Then an MDM2-sgRNA targeting the second promoter of human MDM2 gene was cloned into this vector for producing lentivirus to infect human retinal pigment epithelial (RPE) cells with, which carry a heterozygous genotype of MDM2. lacZ-sgRNA was used as a control. As a result, we discovered that vitreous from experimental rabbits induced a 1.9 ± 0.2 fold increase in Mdm2 and a 2.0 ± 0.2 fold decrease in p53 in the RPE cells with dCas9/lacZ-sgRNA compared to those with dCas9/MDM2-sgRNA, suggesting that dCas9 under the guidance of the MDM2-sgRNA prevented RV-stimulated increase in Mdm2. In addition, we found that the rabbit vitreous significantly enhanced cell proliferation (1.5 ± 0.2 fold), survival against apoptosis (2.2 ± 0.2 fold), migration (10 ± 1.5%) and contraction (112.7 ± 14.1 mm) of the cells with dCas9/lacZ-sgRNA compared with those with dCas9/MDM2-sgRNA. These results indicated that application of the dCas9 targeted to the P2 of MDM2 is a potential therapeutic approach to diseases due to the P2-driven aberrant expression of Mdm2 - such as proliferative vitreoretinopathy.
Chen X, Liu Y, Zhang Y, Kam WR, Pasquale LR, Sullivan DA. Impact of aromatase absence on murine intraocular pressure and retinal ganglion cells. Sci Rep 2018;8(1):3280.Abstract
We hypothesize that aromatase, an enzyme that regulates estrogen production, plays a significant role in the control of intraocular pressure (IOP) and retinal ganglion cells (RGCs). To begin to test our hypothesis, we examined the impact of aromatase absence, which completely eliminates estrogen synthesis, in male and female mice. Studies were performed with adult, age-matched wild type (WT) and aromatase knockout (ArKO) mice. IOP was measured in a masked fashion in both eyes of conscious mice at 12 and 24 weeks of age. Retinas were obtained and processed for RGC counting with a confocal microscope. IOP levels in both 12- and 24-week old female ArKO mice were significantly higher than those of age- and sex-matched WT controls. The mean increase in IOP was 7.9% in the 12-week-, and 19.7% in the 24-week-old mice, respectively. These changes were accompanied by significant 9% and 7% decreases in RGC numbers in the ArKO female mice, relative to controls, at 12- and 24-weeks, respectively. In contrast, aromatase deficiency did not lead to an increased IOP in male mice. There was a significant reduction in RGC counts in the 12-, but not 24-, week-old male ArKO mice, as compared to their age- and sex-matched WT controls. Overall, our findings show that aromatase inhibition in females is associated with elevated IOP and reduced RGC counts.
Chen XH, Amorim JA, Moustafa GA, Lee J-J, Yu Z, Ishihara K, Iesato Y, Barbisan P, Ueta T, Togka KA, Lu L, Sinclair DA, Vavvas DG. Neuroprotective effects and mechanisms of action of nicotinamide mononucleotide (NMN) in a photoreceptor degenerative model of retinal detachment. Aging (Albany NY) 2020;12Abstract
Currently, no pharmacotherapy has been proven effective in treating photoreceptor degeneration in patients. Discovering readily available and safe neuroprotectants is therefore highly sought after. Here, we investigated nicotinamide mononucleotide (NMN), a precursor of nicotinamide adenine dinucleotide (NAD), in a retinal detachment (RD) induced photoreceptor degeneration. NMN administration after RD resulted in a significant reduction of TUNEL photoreceptors, CD11b macrophages, and GFAP labeled glial activation; a normalization of protein carbonyl content (PCC), and a preservation of the outer nuclear layer (ONL) thickness. NMN administration significantly increased NAD levels, SIRT1 protein expression, and heme oxygenase-1 (HO-1) expression. Delayed NMN administration still exerted protective effects after RD. Mechanistic studies using 661W cells revealed a SIRT1/HO-1 signaling as a downstream effector of NMN-mediated protection under oxidative stress and LPS stimulation. In conclusion, NMN administration exerts neuroprotective effects on photoreceptors after RD and oxidative injury, suggesting a therapeutic avenue to treating photoreceptor degeneration.
Cheng L, Wong LJ, Yan N, Han RC, Yu H, Guo C, Batsuuri K, Zinzuwadia A, Guan R, Cho K-S, Chen DF. Ezh2 does not mediate retinal ganglion cell homeostasis or their susceptibility to injury. PLoS One 2018;13(2):e0191853.Abstract
Epigenetic predisposition is thought to critically contribute to adult-onset disorders, such as retinal neurodegeneration. The histone methyltransferase, enhancer of zeste homolog 2 (Ezh2), is transiently expressed in the perinatal retina, particularly enriched in retinal ganglion cells (RGCs). We previously showed that embryonic deletion of Ezh2 from retinal progenitors led to progressive photoreceptor degeneration throughout life, demonstrating a role for embryonic predisposition of Ezh2-mediated repressive mark in maintaining the survival and function of photoreceptors in the adult. Enrichment of Ezh2 in RGCs leads to the question if Ezh2 also mediates gene expression and function in postnatal RGCs, and if its deficiency changes RGC susceptibility to cell death under injury or disease in the adult. To test this, we generated mice carrying targeted deletion of Ezh2 from RGC progenitors driven by Math5-Cre (mKO). mKO mice showed no detectable defect in RGC development, survival, or cell homeostasis as determined by physiological analysis, live imaging, histology, and immunohistochemistry. Moreover, RGCs of Ezh2 deficient mice revealed similar susceptibility against glaucomatous and acute optic nerve trauma-induced neurodegeneration compared to littermate floxed or wild-type control mice. In agreement with the above findings, analysis of RNA sequencing of RGCs purified from Ezh2 deficient mice revealed few gene changes that were related to RGC development, survival and function. These results, together with our previous report, support a cell lineage-specific mechanism of Ezh2-mediated gene repression, especially those critically involved in cellular function and homeostasis.
Chiou CA, Gragoudas E. Retinal Detachment in a 40-Year-Old Man With Sturge-Weber Syndrome. JAMA Ophthalmol 2021;
Cho HY, Nasir HH, Sobrin L. Focal laser photocoagulation and photodynamic therapy for lupus choroidopathy. Lupus 2014;23(4):412-6.Abstract
PURPOSE: To describe the results of photodynamic therapy (PDT) and/or focal laser photocoagulation in the treatment of serous retinal detachments secondary to lupus choroidopathy. METHODS: The medical records of three patients with serous detachments secondary to lupus choroidopathy who were treated with PDT and/or focal laser photocoagulation were reviewed. Concomitant systemic medical therapy as well as visual acuity and optical coherence tomography (OCT) outcomes were recorded. RESULTS: All patients received systemic immunosuppressive therapy and had control of their extraocular manifestations prior to PDT and/or laser photocoagulation. One patient received only focal laser photocoagulation and had complete resolution of the subretinal fluid on OCT. The two other patients received a combination of PDT and focal laser treatment. One had improvement in vision and resolution of subretinal fluid on OCT. The second patient, who had longstanding lupus choroidopathy and associated subretinal fluid and macular edema, had only a significant decrease in fluid on OCT but no vision improvement. CONCLUSION: In conjunction with control of systemic disease, PDT and/or focal laser photocoagulation can be successful in resolving subretinal fluid secondary to lupus choroidopathy.
Choi HJ, Wang R, Jakobs TC. Single-Cell Dissociation and Characterization in the Murine Retina and Optic Nerve. Methods Mol Biol 2018;1695:311-334.Abstract
Recent technological advances have extended the range of analytic tools to very small samples. It is now possible to assay the transcriptome, and in some cases even the proteome, of single cells reliably. This allows addressing novel questions, such as the genotype/phenotype relationships of single neurons, heterogeneity within individual cells of the same type, or the basis of differential vulnerability to injury. An important prerequisite for these kinds of studies is the ability to isolate well-defined individual cells without contamination by adjacent tissue. In the retina and optic nerve, cells of different types and functions are closely intermingled, limiting the use of standard methods such as laser capture microdissection. Here, we describe a simple method to isolate morphologically intact cells from the retina and the optic nerve and discuss considerations in recognizing and isolating different cell types after dissociation.
Chou J, Daly MK. Reply. Retina 2017;37(10):e118.
Chung DC, Bertelsen M, Lorenz B, Pennesi ME, Leroy BP, Hamel CP, Pierce E, Sallum J, Larsen M, Stieger K, Preising M, Weleber R, Yang P, Place E, Liu E, Schaefer G, DiStefano-Pappas J, Elci OU, McCague S, Wellman JA, High KA, Reape KZ. The Natural History of Inherited Retinal Dystrophy Due to Biallelic Mutations in the RPE65 Gene. Am J Ophthalmol 2019;199:58-70.Abstract
PURPOSE: To delineate the natural history of visual parameters over time in individuals with biallelic RPE65 mutation-associated inherited retinal dystrophy (IRD); describe the range of causative mutations; determine potential genotype/phenotype relationships; and describe the variety of clinical diagnoses. DESIGN: Global, multicenter, retrospective chart review. METHODS: Study Population: Seventy individuals with biallelic RPE65 mutation-associated IRD. PROCEDURES: Data were extracted from patient charts. MEASUREMENTS: Visual acuity (VA), Goldmann visual field (GVF), optical coherence tomography, color vision testing, light sensitivity testing, and electroretinograms (retinal imaging and fundus photography were collected and analyzed when available). RESULTS: VA decreased with age in a nonlinear, positive-acceleration relationship (P < .001). GVF decreased with age (P < .0001 for both V4e and III4e), with faster GVF decrease for III4e stimulus vs V4e (P = .0114, left eye; P = .0076, right eye). On average, a 1-year increase in age decreased III4e GVF by ∼25 sum total degrees in each eye while V4e GVF decreased by ∼37 sum total degrees in each eye, although individual variability was observed. A total of 78 clinical diagnoses and 56 unique RPE65 mutations were recorded, without discernible RPE65 mutation genotype/phenotype relationships. CONCLUSIONS: The number of clinical diagnoses and lack of a consistent RPE65 mutation-to-phenotype correlation underscore the need for genetic testing. Significant relationships between age and worsening VA and GVF highlight the progressive loss of functional retina over time. These data may have implications for optimal timing of treatment for IRD attributable to biallelic RPE65 mutations.
Clermont A, Murugesan N, Zhou Q, Kita T, Robson PA, Rushbrooke LJ, Evans MD, Aiello LP, Feener EP. Plasma Kallikrein Mediates Vascular Endothelial Growth Factor-Induced Retinal Dysfunction and Thickening. Invest Ophthalmol Vis Sci 2016;57(6):2390-9.Abstract

PURPOSE: Plasma kallikrein is a serine protease and circulating component of inflammation, which exerts clinically significant effects on vasogenic edema. This study examines the role of plasma kallikrein in VEGF-induced retinal edema. METHODS: Intravitreal injections of VEGF and saline vehicle were performed in plasma prekallikrein-deficient (KLKB1-/-) and wild-type (WT) mice, and in both rats and mice receiving a selective plasma kallikrein inhibitor, VA999272. Retinal vascular permeability (RVP) and retinal thickness were measured by Evans blue permeation and optical coherence tomography, respectively. The retinal kallikrein kinin system was examined by Western blotting and immunohistochemistry. Retinal neovascularization was investigated in KLKB1-/- and WT mice subjected to oxygen-induced retinopathy. RESULTS: Vascular endothelial growth factor-induced RVP and retinal thickening were reduced in KLKB1-/- mice by 68% and 47%, respectively, compared to VEGF responses in WT mice. Plasma kallikrein also contributes to TNFα-induced retinal thickening, which was reduced by 52% in KLKB1-/- mice. Systemic administration of VA999272 reduced VEGF-induced retinal thickening by 57% (P < 0.001) in mice and 53% (P < 0.001) in rats, compared to vehicle-treated controls. Intravitreal injection of VEGF in WT mice increased plasma prekallikrein in the retina, which was diffusely distributed throughout the inner and outer retinal layers. Avascular and neovascular areas induced by oxygen-induced retinopathy were similar in WT and KLKB1-/- mice. CONCLUSIONS: Vascular endothelial growth factor increases extravasation of plasma kallikrein into the retina, and plasma kallikrein is required for the full effects of VEGF on RVP and retinal thickening in rodents. Systemic plasma kallikrein inhibition may provide a therapeutic opportunity to treat VEGF-induced retina edema.

Comin CH, Tsirukis DI, Sun Y, Xu X. Quantification of retinal blood leakage in fundus fluorescein angiography in a retinal angiogenesis model. Sci Rep 2021;11(1):19903.Abstract
Blood leakage from the vessels in the eye is the hallmark of many vascular eye diseases. One of the preclinical mouse models of retinal blood leakage, the very-low-density-lipoprotein receptor deficient mouse (Vldlr-/-), is used for drug screening and mechanistic studies. Vessel leakage is usually examined using Fundus fluorescein angiography (FFA). However, interpreting FFA images of the Vldlr-/- model is challenging as no automated and objective techniques exist for this model. A pipeline has been developed for quantifying leakage intensity and area including three tasks: (i) blood leakage identification, (ii) blood vessel segmentation, and (iii) image registration. Morphological operations followed by log-Gabor quadrature filters were used to identify leakage regions. In addition, a novel optic disk detection algorithm based on graph analysis was developed for registering the images at different timepoints. Blood leakage intensity and area measured by the methodology were compared to ground truth quantifications produced by two annotators. The relative difference between the quantifications from the method and those obtained from ground truth images was around 10% ± 6% for leakage intensity and 17% ± 8% for leakage region. The Pearson correlation coefficient between the method results and the ground truth was around 0.98 for leakage intensity and 0.94 for leakage region. Therefore, we presented a computational method for quantifying retinal vascular leakage and vessels using FFA in a preclinical angiogenesis model, the Vldlr-/- model.
Corral-Serrano JC, Lamers IJC, van Reeuwijk J, Duijkers L, Hoogendoorn ADM, Yildirim A, Argyrou N, Ruigrok RAA, Letteboer SJF, Butcher R, van Essen MD, Sakami S, van Beersum SEC, Palczewski K, Cheetham ME, Liu Q, Boldt K, Wolfrum U, Ueffing M, Garanto A, Roepman R, Collin RWJ. PCARE and WASF3 regulate ciliary F-actin assembly that is required for the initiation of photoreceptor outer segment disk formation. Proc Natl Acad Sci U S A 2020;117(18):9922-9931.Abstract
The outer segments (OS) of rod and cone photoreceptor cells are specialized sensory cilia that contain hundreds of opsin-loaded stacked membrane disks that enable phototransduction. The biogenesis of these disks is initiated at the OS base, but the driving force has been debated. Here, we studied the function of the protein encoded by the photoreceptor-specific gene , which is mutated in inherited retinal dystrophy (RP54). We demonstrate that C2orf71/PCARE (photoreceptor cilium actin regulator) can interact with the Arp2/3 complex activator WASF3, and efficiently recruits it to the primary cilium. Ectopic coexpression of PCARE and WASF3 in ciliated cells results in the remarkable expansion of the ciliary tip. This process was disrupted by small interfering RNA (siRNA)-based down-regulation of an actin regulator, by pharmacological inhibition of actin polymerization, and by the expression of PCARE harboring a retinal dystrophy-associated missense mutation. Using human retinal organoids and mouse retina, we observed that a similar actin dynamics-driven process is operational at the base of the photoreceptor OS where the PCARE module and actin colocalize, but which is abrogated in mice. The observation that several proteins involved in retinal ciliopathies are translocated to these expansions renders it a potential common denominator in the pathomechanisms of these hereditary disorders. Together, our work suggests that PCARE is an actin-associated protein that interacts with WASF3 to regulate the actin-driven expansion of the ciliary membrane at the initiation of new outer segment disk formation.

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