Spots In Fundus Research Articles

Nonredundant Role of Leishmanolysin-Like (Lmln) Zinc-Metallopeptidase in Retinal Homeostasis

To determine if Lmln, a Zn-metallopeptidase, is important for retinal homeostasis. Combining an unbiased N-ethyl-N-nitrosourea mutagenesis pipeline in mice with optical coherence tomography (OCT) screening and automated meiotic mapping, we identified an allele (nemeth) that seemed to be associated with outer nuclear layer (ONL) thinning. Since nemeth was predicted to lead to a nonsense mutation of the Lmln gene, we targeted Lmln using CRISPR/Cas-9 technology and characterized the impact on retinal anatomy and function. OCT imaging demonstrated an outer retinal degeneration in Lmln-/- mice (P = 7.3 × 10-9 for ONL at 2 m) that progressed over the first 6 months of life and then stabilized. Light microscopy showed loss of ONL nuclei (P ranged between .00033 and .0097 for posterior measurements), and a TUNEL assay revealed a small but significant increase in apoptosis (P = .034). Lmln-/- mice accumulated fundus spots (P = .0030 by 2 m of age) and activated subretinal microglia (p ranged from .0007 to 8 × 10-13 for Gal3+ cells). Scotopic electroretinography demonstrated a decrease in retinal function in Lmln-/- mice both at 6 m (only a-wave, P < .01 for all stimuli) and at 10 m of age (P < .01 for both a-wave and b-wave with all stimuli). Our work revealed a previously unknown essential requirement for Lmln in maintaining retinal anatomy and function. Further studies using this new model will be aimed at determining the cellular expression of Lmln and its mechanisms of action within the retina.

E3 ubiquitin ligase Herc3 deficiency leads to accumulation of subretinal microglia and retinal neurodegeneration

Activated microglia have been implicated in the pathogenesis of age-related macular degeneration (AMD), diabetic retinopathy, and other neurodegenerative and neuroinflammatory disorders, but our understanding of the mechanisms behind their activation is in infant stages. With the goal of identifying novel genes associated with microglial activation in the retina, we applied a semiquantitative fundus spot scoring scale to an unbiased, state-of-the-science mouse forward genetics pipeline. A mutation in the gene encoding the E3 ubiquitin ligase Herc3 led to prominent accumulation of fundus spots. CRISPR mutagenesis was used to generate Herc3-/- mice, which developed prominent accumulation of fundus spots and corresponding activated Iba1 + /CD16 + subretinal microglia, retinal thinning on OCT and histology, and functional deficits by Optomotory and electrophysiology. Bulk RNA sequencing identified activation of inflammatory pathways and differentially expressed genes involved in the modulation of microglial activation. Thus, despite the known expression of multiple E3 ubiquitin ligases in the retina, we identified a non-redundant role for Herc3 in retinal homeostasis. Our findings are significant given that a dysregulated ubiquitin–proteasome system (UPS) is important in prevalent retinal diseases, in which activated microglia appear to play a role. This association between Herc3 deficiency, retinal microglial activation and retinal degeneration merits further study.

Forward genetic screening using fundus spot scale identifies an essential role for Lipe in murine retinal homeostasis

Microglia play a role in the pathogenesis of many retinal diseases. Fundus spots in mice often correlate with the accumulation of activated subretinal microglia. Here we use a semiquantitative fundus spot scoring scale in combination with an unbiased, state-of-the-science forward genetics pipeline to identify causative associations between chemically induced mutations and fundus spot phenotypes. Among several associations, we focus on a missense mutation in Lipe linked to an increase in yellow fundus spots in C57BL/6J mice. Lipe−/− mice generated using CRISPR-Cas9 technology are found to develop accumulation of subretinal microglia, a retinal degeneration with decreased visual function, and an abnormal retinal lipid profile. We establish an indispensable role of Lipe in retinal/RPE lipid homeostasis and retinal health. Further studies using this new model will be aimed at determining how lipid dysregulation results in the activation of subretinal microglia and whether these microglia also play a role in the subsequent retinal degeneration.

Genetic Interaction between Mfrp and Adipor1 Mutations Affect Retinal Disease Phenotypes.

Adipor1tm1Dgen and Mfrprd6 mutant mice share similar eye disease characteristics. Previously, studies established a functional relationship of ADIPOR1 and MFRP proteins in maintaining retinal lipidome homeostasis and visual function. However, the independent and/or interactive contribution of both genes to similar disease phenotypes, including fundus spots, decreased axial length, and photoreceptor degeneration has yet to be examined. We performed a gene-interaction study where homozygous Adipor1tm1Dgen and Mfrprd6 mice were bred together and the resulting doubly heterozygous F1 offspring were intercrossed to produce 210 F2 progeny. Four-month-old mice from all nine genotypic combinations obtained in the F2 generation were assessed for white spots by fundus photo documentation, for axial length by caliper measurements, and for photoreceptor degeneration by histology. Two-way factorial ANOVA was performed to study individual as well as gene interaction effects on each phenotype. Here, we report the first observation of reduced axial length in Adipor1tmlDgen homozygotes. We show that while Adipor1 and Mfrp interact to affect spotting and degeneration, they act independently to control axial length, highlighting the complex functional association between these two genes. Further examination of the molecular basis of this interaction may help in uncovering mechanisms by which these genes perturb ocular homeostasis.

A Chimeric Cfh Transgene Leads to Increased Retinal Oxidative Stress, Inflammation, and Accumulation of Activated Subretinal Microglia in Mice

Variants of complement factor H (Cfh) affecting short consensus repeats (SCRs) 6 to 8 increase the risk of age-related macular degeneration. Our aim was to explore the effect of expressing a Cfh variant on the in vivo susceptibility of the retina and RPE to oxidative stress and inflammation, using chimeric Cfh transgenic mice (chCfhTg). The chCfhTg and age-matched C57BL/6J (B6) mice were subjected to oxidative stress by either normal aging, or by exposure to a combination of oral hydroquinone (0.8% HQ) and increased light. Eyes were collected for immunohistochemistry of RPE-choroid flat mounts and of retinal sections, ELISA, electron microscopy, and RPE/microglia gene expression analysis. Aging mice to 2 years led to an increased accumulation of basal laminar deposits, subretinal microglia/macrophages (MG/MΦ) staining for CD16 and for malondialdehyde (MDA), and MDA-modified proteins in the retina in chCfhTg compared to B6 mice. The chCfhTg mice maintained on HQ diet and increased light showed greater deposition of basal laminar deposits, more accumulation of fundus spots suggestive of MG/MΦ, and increased deposition of C3d in the sub-RPE space, compared to controls. In addition, chCfhTg mice demonstrated upregulation of NLRP3, IP-10, CD68, and TREM-2 in the RNA isolates from RPE/MG/MΦ. Expression of a Cfh transgene introducing a variant in SCRs 6 to 8 was sufficient to lead to increased retinal/RPE susceptibility to oxidative stress, a proinflammatory MG/MΦ phenotype, and a proinflammatory RPE/MG/MΦ gene expression profile in a transgenic mouse model. Our data suggest that altered interactions of Cfh with MDA-modified proteins may be relevant in explaining the effects of the Cfh variant.

Differences in the distribution, phenotype and gene expression of subretinal microglia/macrophages in C57BL/6N (Crb1 rd8/rd8) versus C57BL6/J (Crb1 wt/wt) mice.

BackgroundMicroglia/macrophages (MG/MΦ) are found in the subretinal space in both mice and humans. Our goal was to study the spatial and temporal distribution, the phenotype, and gene expression of subretinal MG/MΦ in mice with normal retinas and compare them to mice with known retinal pathology.MethodsWe studied C57BL/6 mice with (C57BL/6N), or without (C57BL/6J) the rd8 mutation in the Crb1 gene (which, in the presence of yet unidentified permissive/modifying genes, leads to a retinal degeneration), and documented their fundus appearance and the change with aging. Immunostaining of retinal pigment epithelium (RPE) flat mounts was done for 1) Ionized calcium binding adaptor (Iba)-1, 2) FcγIII/II Receptor (CD16/CD32, abbreviated as CD16), and 3) Macrophage mannose receptor (MMR). Reverse-transcription quantitative PCR (RT-qPCR) was done for genes involved in oxidative stress, complement activation and inflammation.ResultsThe number of yellow fundus spots correlated highly with subretinal Iba-1+ cells. The total number of subretinal MG/MΦ increased with age in the rd8 mutant mice, but not in the wild-type (WT) mice. There was a centripetal shift in the distribution of the subretinal MG/MΦ with age. Old rd8 mutant mice had a greater number of CD16+ MG/MΦ. CD16+ cells had morphological signs of activation, and this was most prominent in old rd8 mutant mice (P <1×10−8 versus old WT mice). Subretinal MG/MΦ in rd8 mutant mice also expressed iNOS and MHC-II, and had ultrastructural signs of activation. Finally, rd8 mutant mouse RPE/ MG/MΦ RNA isolates showed an upregulation of Ccl2, CFB, C3, NF-kβ, CD200R and TNF-alpha. The retinas of rd8 mutant mice showed upregulation of HO-1, C1q, C4, and Nrf-2.ConclusionsWhen compared to C57BL/6J mice, C57BL/6N mice demonstrate increased accumulation of subretinal MG/MΦ, displaying phenotypical, morphological, and gene-expression characteristics consistent with a pro-inflammatory shift. These changes become more prominent with aging and are likely due to the combination of the rd8 mutation and yet unidentified permissive/modulatory genes in the C57BL/6N mice. In contrast, aging leads to a scavenging phenotype in the C57BL/6J subretinal microglia/macrophages.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-014-0221-4) contains supplementary material, which is available to authorized users.

Multifocal choroïditis: is it a granulomatosis close to sarcoidosis?

AbstractPurpose Multifocal choroiditis is an idiopathic posterior uveitis. It combines small white spots in fundus of eye and recurrent intraocular inflammation. Some biological or radiological manifestations of sarcoidosis may be found in these patients.Methods We report a case of severe multifocal choroiditis associated with systemic granulomatosis. The aim of our study was to describe the clinical and therapeutic aspects, and discuss the etiopathogenic approach of this rare entity.Results A 45 years old women who consults for blurred vision. Visual acuity is reduced at 1/20 P8 in right eye and 3/10 P5 in the left. There is a hyalite + bilaterally. Peri papillary atrophy, hemorrhage around the macula, multiple white and pigmentis small spots was found in fundus of eyes. Retinal thickening and involvements of the pigment epithelium and choroid are revealed by macular OCT in the right eye. The fluorescein angiography show hypofluorescence of chorioretinal spots in early time, a window effect scarring and bilateral papillitis. The ECA is 74 UECA. Chest scan reveal a non specific parenchymal micronodules. The patient received systemic corticosteroids. Control OCT show a subretinal fibrosis explaining the introduction of immunosuppressant treatment. The final visual acuity is 1/10 right and 12/10 left with a decline of 3 years.Conclusion Although intraocular manifestations of multifocal choroiditis, it most correspond to a systemic granulomatosis near sarcoidosis.

White spots in the central fundus in diabetic children and adolescents.

Previously, small defects in the retinal pigment epithelium appearing as depigmented spots in the fundus photographs have been observed in a high proportion of adult diabetic patients. In order to evaluate whether these changes already occur in children we examined the black-and-white and colour fundus photographs of 206 diabetic children aged 4.6-19.6 years (median 12.6), with the median duration of diabetes of 4.7 years (range 0.0-14.2). Early signs of retinopathy were observed in 27 (13.1%) of them. The control group was composed of 45 healthy children aged 8.1-16.6 years (median 11.8). One or more tiny white spots in the fundus of one or both eyes were observed in 97 diabetics (47.1%), more often in those with retinopathy than in those without (66.7% vs. 44.1%, p less than 0.001). In the control group similar spots were observed in 24 children (53.5%). Only in a small proportion of children (4.4% of both diabetic and control patients) were the spots numerous. In children most of the white spots in the fundus may represent drusen type deposits rather than defects in the pigment epithelium.

Birdshot Retinochoroidopathy: Measurement of the Posterior Fundus Spots and Macular Edema Using a Retinal Thickness Analyzer, before and after Treatment

To measure the retinal thickness in the macular area and at the typical fundus spots in a patient with birdshot retinochoroidopathy, using the retinal thickness analyzer (RTA), a new image analyzer involving laser-slit biomicroscopy, and to quantify the changes after systemic corticosteroid therapy. A 54-year-old man with posterior uveitis underwent visual acuity measurement, fluorescein and indocyanine green (ICG) angiographies, optical coherence tomography (OCT) and RTA measurements before and after steroid treatment. The thickness at the birdshot spots measured with RTA remained unchanged after treatment, but the thickness at the fovea decreased in both eyes. Fluorescein and ICG angiographies and OCT showed no change with treatment. RTA seems a more sensitive method for assessing changes in macula thickness in the course of birdshot retinochoroidopathy and can help document the effect of treatment.

Sorsby's Fundus Dystrophy

Ever since Sorsby described his pseudoinflammatory dystrophy in five families, its characteristics have been unclear. The findings in ten affected members of a seven-generation pedigree are discussed and the literature is reviewed. Patients with this dominantly inherited fundus dystrophy lose central vision between the second and fourth decade of life. Three variations in the fundus appearances were distinguished: in the first and most common, white to yellow fundus spots (which are not drusen) accompany a disciform macular degeneration; in the second, the fundus spots are absent; in the third, the yellow deposits are associated with atrophic macular degeneration. Atrophy of the retina, pigment epithelium, and choroid then slowly progresses toward the periphery. Treatment does not halt the progress of the disease. Although variations in this dystrophy may be examples of genetic heterogeneity, Sorsby's fundus dystrophy is a distinct clinical disorder.