Interspecies Correlations between Human and Mouse NR2E3-Associated Recessive Disease.

NR2E3-associated recessive disease in humans is historically defined by congenital night blinding retinopathy, characterized by an initial increase in short-wavelength (S)-cone sensitivity and progressive loss of rod and cone function. The retinal degeneration 7 (rd7) murine model, harboring a recessive mutation in the mouse ortholog of NR2E3, has been a well-studied disease model and recently evaluated as a therapeutic model for NR2E3-associated retinal degenerations. This study aims to draw parallels between human and mouse NR2E3-related disease through examination of spectral domain optical coherence tomography (SD-OCT) imaging between different stage of human disease and its murine counterpart. We propose that SD-OCT is a useful non-invasive diagnostic tool to compare human clinical dystrophy presentation with that of the rd7 mouse and make inference that may be of therapeutically relevance. Additionally, a longitudinal assessment of rd7 disease progression, utilizing available clinical data from our patients as well as extensive retrospective analysis of visual acuity data from published cases of human NR2E3-related disease, was curated to identify further valuable correlates between human and mouse Nr2e3 disease. Results of this study validate the slow progression of NR2E3-associated disease in humans and the rd7 mice and identify SD-OCT characteristics in patients at or near the vascular arcades that correlate well with the whorls and rosettes that are seen also in the rd7 mouse and point to imaging features that appear to be associated with better preserved S-cone mediated retinal function. The correlation of histological findings between rd7 mice and human imaging provides a solid foundation for diagnostic use of pathophysiological and prognostic information to further define characteristics and a relevant timeline for therapeutic intervention in the field of NR2E3-associated retinopathies.

Phenotypic expression of Bardet-Biedl syndrome in patients homozygous for the common M390R mutation in the BBS1 gene.

PURPOSE: To characterize the phenotype of Bardet-Biedl syndrome (BBS) patients homozygous for the BBS1 M390R mutation. METHODS: Three patients [PT1, F, 27 years old (yo) at last examination, 14-year follow-up (F/U) PT2, F, 15-yo PT3, M, 15-yo, both 1-year F/U] underwent eye exams, Goldmann visual fields (GVFs), dark- (DA) and light-adapted (LA) electroretinograms (ERGs), spectral domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF). Vision and systemic history were also collected. RESULTS: All patients had night blindness, hyperopic astigmatism, ptosis or mild blepharospasm, foot polydactyly, 5th finger clinodactyly, history of headaches, and variable, diet-responsive obesity. Two had asthma, PT1 was developmentally delayed, PT2 had Asperger-like symptoms, and PT3 had normal cognition. At age 14, acuity was 20/100 in PT1, who had nystagmus since age 2, 20/40 in PT2 and 20/30 in PT3. By 27yo PT1 progressed to 20/320, by 15 yo PT2 was 20/60 and PT3 remained stable. PT1 had well preserved peripheral GVFs, with minimal progression over 10 years of F/U. PT2 and PT3 presented with ring scotomas and I4e<5°. All patients had severe generalized visual sensitivity depression. ERGs were consistently recordable (also rod ERG in PT3 after 60 min DA), but progressed to non-recordable in PT1. Mixed DA ERGs exhibited electronegativity. In PT3, this was partly due to a bleaching effect during bright-flash DA averaging, partly to ON≫OFF LA response compromise. PT2 and 3 had, on SD-OCTs, generalized macular thinning, normal retinal lamination, and widespread photoreceptor outer/inner segment attenuation except foveally, and multiple rings of abnormal FAF configuring a complex bull's eye-pattern. PT1 had macular atrophy. All patients also had peripapillary nerve fiber layer thickening. CONCLUSIONS: The observed phenotype matches very closely that reported in patients by Azari et al. (IOVS 2006) and in the Bbs1-M390R knock-in mouse model, and expands it to the characterization of important ERG response characteristics that provide insight in the pathogenesis of retinopathy in these patients. Our findings confirm the consistent pathogenicity of the BBS1 M390R mutation.

Preconditioning protects the retinal pigment epithelium cells from oxidative stress-induced cell death.

PURPOSE: The cytotoxic effects of oxidative stress, which play an important role in ocular diseases, are well known. In this study, we investigated the effect of non-lethal doses of oxidative stress on various cell functions, namely cell viability, cell attachment and cell migration in a widely used retinal pigment epithelium (RPE) cell line (ARPE-19). METHODS: A single exposure to various concentrations of hydrogen peroxide (H(2)O(2)) was used to establish a dose response for H(2)O(2)-induced cell death. Other cellular responses, such as changes in cell attachment and migration, were monitored after exposure to increasing doses. Finally, the effects of preconditioning cells with increasing non-lethal doses of H(2)O(2), with and without a subsequent exposure to lethal doses of H(2)O(2), were determined. RESULTS: The optimum dose for inducing cell death in ARPE-19 cells was between 900 and 1000 microm H(2)O(2). Preconditioning the cells with 1, 10 and 50 microm of H(2)O(2) provided a dose-dependent protection against cell death induced by a lethal dose (900-1000 microm) of H(2)O(2). Preconditioning with higher doses caused cells to become more susceptible to the cytotoxic effects of the lethal dose. Although H(2)O(2) increased cell attachment in lower doses, it induced a dose-dependent inhibition of cell attachment to the substrate in higher doses. H(2)O(2) did not affect cell migration in sub-lethal doses. CONCLUSION: Preconditioning RPE cells with limited exposure to non-lethal oxidative stress confers significant protection against subsequent H(2)O(2)-induced cell death. It also affects cell attachment in a dose-specific manner. This finding may help in understanding the pathogenesis of diseases in which oxidative stress plays an important role and in determining the suitability of certain treatment strategies, in particular RPE transplantation in the treatment of age-related macular degeneration.