Novel grading system for quantification of cystic macular lesions in Usher syndrome

International audienceBackground: To evaluate novel grading system used to quantify optical coherence tomography (OCT) scans for cystic macular lesions (CML) in Usher syndrome (USH) patients, focusing on CML associated alterations in MOY7A and USH2A mutations.Methods : Two readers evaluated 76 patients’ (mean age 42 ± 14 years) data prospectively uploaded on Eurush database. OCT was used to obtain high quality cross-sectional images through the fovea. The CML was graded as none, mild, moderate or severe, depending on the following features set: subretinal fluid without clearly detectable CML boundaries; central macular thickness; largest diameter of CML; calculated mean of all detectable CML; total number of detectable CML; retinal layers affected by CML. Intra-and inter-grader reproducibility was evaluated. Results : CML were observed in 37 % of USH eyes, while 45 % were observed in MYO7A and 29 % in USH2A cases. Of those with CML: 52 % had mild, 22 % had moderate and 26 % had severe changes, respectively. CML were found in following retinal layers: 50 % inner nuclear layer, 44 % outer nuclear layer, 6 % retinal ganglion cell layer. For the inter-grader repeatability analysis, agreements rates for CML were 97 % and kappa statistics was 0.91 (95 % CI 0.83-0.99). For the intra-grader analysis, agreement rates for CML were 98 %, while kappa statistics was 0.96 (95 % CI 0.92-0.99). Conclusions : The novel grading system is a reproducible tool for grading OCT images in USH complicated by CML, and potentially could be used for objective tracking of macular pathology in clinical therapy trials

Transplantation of Photoreceptor and Total Neural Retina Preserves Cone Function in P23H Rhodopsin Transgenic Rat

Background: Transplantation as a therapeutic strategy for inherited retinal degeneration has been historically viewed to restore vision as a method by replacing the lost retinal cells and attempting to reconstruct the neural circuitry with stem cells, progenitor cells and mature neural retinal cells. Methods and Findings: We present evidence for an alternative strategy aimed at preventing the secondary loss of cones, the most crucial photoreceptors for vision, by transplanting normal photoreceptors cells into the eye of the P23H rat, a model of dominant retinitis pigmentosa. We carried out transplantation of photoreceptors or total neural retina in 3-monthold P23H rats and evaluated the function and cell counts 6 months after surgery. In both groups, cone loss was significantly reduced (10%) in the transplanted eyes where the cone outer segments were found to be considerably longer. This morphological effect correlated with maintenance of the visual function of cones as scored by photopic ERG recording, but more precisely with an increase in the photopic b-wave amplitudes by 100 % and 78 % for photoreceptor transplantation and whole retinal transplantation respectively. Conclusions: We demonstrate here that the transplanted tissue prevents the loss of cone function, which is furthe

℮-conome: an automated tissue counting platform of cone photoreceptors for rodent models of retinitis pigmentosa

<p>Abstract</p> <p>Background</p> <p>Retinitis pigmentosa is characterized by the sequential loss of rod and cone photoreceptors. The preservation of cones would prevent blindness due to their essential role in human vision. Rod-derived Cone Viability Factor is a thioredoxin-like protein that is secreted by rods and is involved in cone survival. To validate the activity of Rod-derived Cone Viability Factors (RdCVFs) as therapeutic agents for treating retinitis Pigmentosa, we have developed e-conome, an automated cell counting platform for retinal flat mounts of rodent models of cone degeneration. This automated quantification method allows for faster data analysis thereby accelerating translational research.</p> <p>Methods</p> <p>An inverted fluorescent microscope, motorized and coupled to a CCD camera records images of cones labeled with fluorescent peanut agglutinin lectin on flat-mounted retinas. In an average of 300 fields per retina, nine Z-planes at magnification X40 are acquired after two-stage autofocus individually for each field. The projection of the stack of 9 images is subject to a threshold, filtered to exclude aberrant images based on preset variables. The cones are identified by treating the resulting image using 13 variables empirically determined. The cone density is calculated over the 300 fields.</p> <p>Results</p> <p>The method was validated by comparison to the conventional stereological counting. The decrease in cone density in <it>rd1 </it>mouse was found to be equivalent to the decrease determined by stereological counting. We also studied the spatiotemporal pattern of the degeneration of cones in the <it>rd1 </it>mouse and show that while the reduction in cone density starts in the central part of the retina, cone degeneration progresses at the same speed over the whole retinal surface. We finally show that for mice with an inactivation of the Nucleoredoxin-like genes <it>Nxnl1 </it>or <it>Nxnl2 </it>encoding RdCVFs, the loss of cones is more pronounced in the ventral retina.</p> <p>Conclusion</p> <p>The automated platform ℮-conome used here for retinal disease is a tool that can broadly accelerate translational research for neurodegenerative diseases.</p

High prevalence of PRPH2 in autosomal dominant retinitis pigmentosa in France and characterization of biochemical and clinical features.

International audiencePURPOSE:To assess the prevalence of PRPH2 in autosomal dominant retinitis pigmentosa (adRP), to report six novel mutations, to characterize the biochemical features of a recurrent novel mutation and to study the clinical features of adRP patients.DESIGN:Retrospective clinical and molecular genetic study.METHODS:Clinical investigations included visual field testing, fundus examination, high-resolution spectral-domain optical coherence tomography (OCT), fundus autofluorescence imaging and electroretinogram (ERG) recording. PRPH2 was screened by Sanger sequencing in a cohort of 310 French families with adRP. Peripherin-2 protein was produced in yeast and analyzed by Western blot.RESULTS:We identified 15 mutations, including 6 novel and 9 previously reported changes in 32 families, accounting for a prevalence of 10.3% in this adRP population. We showed that a new recurrent p.Leu254Gln mutation leads to protein aggregation, suggesting abnormal folding. The clinical severity of the disease in examined patients was moderate with 78% of the eyes having 1 to 0.5 of visual acuity and 52% of the eyes retaining more than 50% of the visual field. Some patients characteristically showed vitelliform deposits or macular involvement. In some families, pericentral RP or macular dystrophy were found in family members while widespread RP was present in other members of the same families.CONCLUSIONS:The mutations in PRPH2 account for 10.3% of adRP in the French population, which is higher than previously reported (0-8%) This makes PRPH2 the second most frequent adRP gene after RHO in our series. PRPH2 mutations cause highly variable phenotypes and moderate forms of adRP, including mild cases which could be underdiagnosed

NMNAT1 Mutations Cause Leber Congenital Amaurosis

Leber congenital amaurosis (LCA) is an infantile-onset form of inherited retinal degeneration characterized by severe vision loss. Two-thirds of LCA cases are caused by mutations in 17 known disease genes (RetNet Retinal Information Network). Using exome sequencing, we identified a homozygous missense mutation (c.25G>A, p.Val9Met) in NMNAT1 as likely disease-causing in two siblings of a consanguineous Pakistani kindred affected by LCA. This mutation segregated with disease in their kindred, including in three other children with LCA. NMNAT1 resides in the previously identified LCA9 locus and encodes the nuclear isoform of nicotinamide mononucleotide adenylyltransferase, a rate-limiting enzyme in nicotinamide adenine dinucleotide $(NAD^+)$ biosynthesis. Functional studies showed the p.Val9Met mutation decreased NMNAT1 enzyme activity. Sequencing NMNAT1 in 284 unrelated LCA families identified 14 rare mutations in 13 additional affected individuals. These results are the first to link an NMNAT isoform to disease and indicate that NMNAT1 mutations cause LCA

NEUROPROTECTION DES PHOTORECEPTEURS A CONE DANS LES RETINOPATHIES PIGMENTAIRES

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Neurodegenerative and Neuroprotective Effects of Tumor Necrosis Factor (TNF) in Retinal Ischemia: Opposite Roles of TNF Receptor 1 and TNF Receptor 2

Tumor necrosis factor (TNF) is an important factor in various acute and chronic neurodegenerative disorders. In retinal ischemia, we show early, transient upregulation of TNF, TNF receptor 1 (TNF-R1), and TNF-R2 6 hr after reperfusion preceding neuronal cell loss. To assess the specific role of TNF and its receptors, we compared ischemia–reperfusion-induced retinal damage in mice deficient for TNF-R1, TNF-R2, or TNF by quantifying neuronal cell loss 8 d after the insult. Surprisingly, TNF deficiency did not affect overall cell loss, yet absence of TNF-R1 led to a strong reduction of neurodegeneration and lack of TNF-R2 led to an enhancement of neurodegeneration, indicative of TNF-independent and TNF-dependent processes in the retina, with TNF-R1 augmenting neuronal death and TNF-R2 promoting neuroprotection. Western blot analyses of retinas revealed that reduction of neuronal cell loss in TNF-R1 -/- animals correlated with the presence of activated Akt/protein kinase B (PKB). Inhibition of the phosphatidylinositol 3-kinase signaling pathway reverted neuroprotection in TNF-R1-deficient mice, indicating an instrumental role of Akt/PKB in neuroprotection and TNF-R2 dependence of this pathway. Selective inhibition of TNF-R1 function may represent a new approach to reduce ischemia-induced neuronal damage, being potentially superior to strategies aimed at suppression of TNF activity in general.

Monosialoganglioside GM1 reduces ischemia-reperfusion induced injury in the rat retina. Invest Ophthalmol

Purpose. Gangliosides are normal components of cell membranes, contribute to structural rigidity and membrane function, and have been shown to protect against various insults to the brain. This study evaluates the effect of exogenously administered monosialoganglioside GM1 on retinal damage induced by transient retinal ischemia and reperfusion. Methods. Retinal ischemia was induced unilaterally in Long Evans rats by increasing intraocular pressure to 160 mm Hg for 60 minutes. GM1 (30 mg/kg, intraperitoneally) or buffer controls were administered at 48 hours, 24 hours, and 15 minutes before ischemia, and survival time after ischemia was either 8 or 15 days. The degree of retinal damage was assessed by histopathologic study according to Hughes&apos; quantification of ischemic damage. Results. Retinal ischemia led to significant reductions in thickness and cell number, principally in the inner retinal layers (30% to 80%), and to a lesser extent in the outer retinal layers (18% to 42%). Pretreatment with intraperitonealy injected monosialoganglioside GM1 conferred significant protection against retinal ischemic damage either 8 or 15 days after ischemic survival time. After 8 days reperfusion, the ischemic-induced loss in overall retinal thickness was reduced by 70%, and those of the inner nuclear and plexiform layers were reduced by 77% and 44%, respectively. Ischemic-induced ganglion cell, inner nuclear, and outer nuclear layer cell density losses were reduced by 45%, 40%, and 57%, respectively. After 15 days of reperfusion, approximately the same statistically significant differences could be observed in comparison with the 15-day ischemic-reperfusion group. Conclusions. Monosialoganglioside GM1 protects the rat retina from pressure-induced ischemic injury when administered intraperitonealy 2 days before insult. This protection afforded by GM1 can be observed even after 8 days or 15 days of reperfusion. Invest Ophthalmol Vis Sci. 1996; 37:267-273. VFangliosides are naturally occuring glycosphingolipids that contain one or more sialic acids and are particularly abundant in neuronal membranes.&apos; They influence functional dynamics of the cellular membranes on several ways: They contribute to the structural rigidity of the membranes; they are involved in the transfer of information between neighboring cells or between cell surfaces and the extracellular environment (neurotransmitters, hormones); and they modulate cell growth by regulating proliferation and maturation processes controlled by polypeptide growth fac