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International audience; After revolutionizing neuroscience, optogenetic therapy has entered successfully in clinical trials for restoring vision to blind people with degenerative eye diseases, such as retinitis pigmentosa. These clinical trials still have to evaluate the visual acuity achieved by patients and to determine if it reaches its theoretical limit extrapolated from ex vivo experiments. Different strategies are developed in parallel to reduce required light levels and improve information processing by targeting various cell types. For patients with vision loss due to optic atrophy, as in the case of glaucoma, optogenetic cortical stimulation is hampered by light absorption and scattering by the brain tissue. By contrast, ultrasound waves can diffuse widely through the dura mater and the brain tissue as indicated by ultrasound imaging. Based on our recent results in rodents, we propose the sonogenetic therapy relying on activation of the mechanosensitive channel as a very promising vision restoration strategy with a suitable spatiotemporal resolution. Genomic approaches may thus provide efficient brain machine interfaces for sight restoration.

International audience; Purpose: To describe the value of integrating phenotype/genotype data, disease staging, and evaluation of functional vision in patient-centered management of retinal dystrophies.Methods: (1) Cross-sectional structure-function and retrospective longitudinal studies to assess the correlations between standard fundus autofluorescence (FAF), optical coherence tomography, visual acuity (VA), and perimetry (visual field [VF]) examinations to evaluate photoreceptor functional loss in a cohort of patients with rod-cone dystrophy (RCD); (2) flood-illumination adaptive optics (FIAO) imaging focusing on photoreceptor misalignment and orientation of outer segments; and (3) evaluation of the impact of visual impairment in daily life activities, based on functional (visual and mobility) vision assessment in a naturalistic environment in visually impaired subjects with RCD and subjects treated with LuxturnaⓇ for RPE65-related Leber congenital amaurosis before and after therapy.Results: The results of the cross-sectional transversal study showed that (1) VA and macular sensitivity were weakly correlated with the structural variables; and (2) functional impairment (VF) was correlated with reduction of anatomical markers of photoreceptor structure and increased width of autofluorescent ring. The dimensions of the ring of increased FAF evolved faster. Other criteria that differed among groups were the lengths of the ellipsoid zone, the external limiting membrane, and the foveal thickness. FIAO revealed a variety of phenotypes: paradoxical visibility of foveal cones; heterogeneous brightness of cones; dim, inner segment-like, and RPE-like mosaic. Directional illumination by varying orientation of incident light (Stiles-Crawford effect) and the amount of side illumination (gaze-dependent imaging) affected photoreceptor visibility. Mobility assessment under different lighting conditions showed correlation with VF, VA, contrast sensitivity (CS), and dark adaptation, with different predictive values depending on mobility study paradigms and illumination level. At high illumination level (235 lux), VF was a predictor for all mobility performance models. Under low illumination (1 and 2 lux), VF was the most significant predictor of mobility performance variables, while CS best explained the number of collisions and segments. In subjects treated with LuxturnaⓇ, a very favorable impact on travel speed and reduction in the number of collisions, especially at low luminance, was observable 6 months following injection, in both children and adults.Conclusions: Our results suggest the benefit of development and implementation of quantitative and reproducible tools to evaluate the status of photoreceptors and the impact of both visual impairment and novel therapies in real-life conditions. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Electroretinography (ERG) is a clinical test employed to understand and diagnose many retinopathies. ERG is usually performed by placing a macroscopic ring gold wire electrode on the cornea while flashing light onto the eye to measure changes in the transretinal potential. However, macroscopic gold electrodes are severely limiting since they do not provide a flexible interface to contact the sensitive corneal tissue, making this technique highly uncomfortable for the patient. Another major drawback is the opacity of gold electrodes, which only allows them to record the ERG signal on the corneal periphery, preventing central ERG recordings. To overcome the limitations of metal-based macroscopic ERG electrodes, flexible electrodes are fabricated using graphene as a transparent, flexible, and sensitive material. The transparency of the graphene is exploited to fabricate microelectrode arrays (MEAs) that are able to perform multisite recording on the cornea. The graphene-based ERG electrodes are benchmarked against the widely used gold electrodes in a P23H rat model with photoreceptor degeneration. This study shows that the graphene-based ERG electrodes can faithfully record ERGs under a wide range of conditions (light intensity, stage of photoreceptor degeneration, etc.) while offering additional benefits for ERG recordings such as transparency and flexibility., J.d.l.C. and D.N. contributed equally to this work. This project received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement nos. 881603 (GrapheneCore3). This work was within the project FIS2017-85787-R funded by the “Ministerio de Ciencia, Innovación y Universidades” of Spain, the “Agencia Estatal de Investigación (AEI),” and the “Fondo Europeo de Desarrollo Regional (FEDER/UE).” Support was also provided by the French state funds managed by the Agence Nationale de la Recherche within the Programme Investissements d'Avenir, LABEX LIFESENSES (ANR-10-LABX-65) and IHU FOReSIGHT (ANR-18-IAHU-0001). The ICN2 is supported by the Severo Ochoa Centres of Excellence program, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706), and by the CERCAProgram/Generalitat de Catalunya. E.d.C. acknowledges the Spanish MINECO Juan de la Cierva Fellowship JC-2015-25201. This work made use of the Spanish ICTS Network MICRONANOFABS partially supported by MICINN and the ICTS “NANBIOSIS,” more specifically by the Micro-NanoTechnology Unit of the CIBER in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) at the IMB-CNM. J.d.l.C. would like to thank Laura García for the work on the images and figures throughout the whole paper writing process. E.d.C acknowledges the grant RYC2019-027879-I financed by MCIN/AEI /10.13039/501100011033. The project leading to these results have received funding from “la Caixa” Foundation (ID 100010434), under the agreement LCF/PR/HR19/52160003. These activities are co-funded with 50% by the European Regional Development Fund under the framework of the ERFD Operative Programme for Catalunya 2014–2020 with the support of the Department de Recerca i Universitat (GraphCAT 001-P-001702).

International audience; We tested 144 pet rabbits sampled in France between November 2020 and June 2021 for antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by microsphere immunoassay. We reported the first evidence of a natural SARS-CoV-2 infection in rabbits with a low observed seroprevalence between 0.7% and 1.4%

International audience; Rhodopsin-associated (RHO-associated) retinitis pigmentosa (RP) is a progressive retinal disease that currently has no cure. RHO protein misfolding leads to disturbed proteostasis and the death of rod photoreceptors, resulting in decreased vision. We previously identified nonretinoid chaperones of RHO, including YC-001 and F5257-0462, by small-molecule high-throughput screening. Here, we profile the chaperone activities of these molecules toward the cell-surface level of 27 RP-causing human RHO mutants in NIH3T3 cells. Furthermore, using retinal explant culture, we show that YC-001 improves retinal proteostasis by supporting RHO homeostasis in RhoP23H/+ mouse retinae, which results in thicker outer nuclear layers (ONL), indicating delayed photoreceptor degeneration. Interestingly, YC-001 ameliorated retinal immune responses and reduced the number of microglia/macrophages in the RhoP23H/+ retinal explants. Similarly, F5257-0462 also protects photoreceptors in RhoP23H/+ retinal explants. In vivo, intravitreal injection of YC-001 or F5257-0462 microparticles in PBS shows that F5257-0462 has a higher efficacy in preserving photoreceptor function and delaying photoreceptor death in RhoP23H/+ mice. Collectively, we provide proof of principle that nonretinoid chaperones are promising drug candidates in treating RHO-associated RP.

Significance Nowadays, several techniques exist to study and better understand how the brain works (fMRI, EEG, electrophysiology, etc.). Each has its own advantages and disadvantages (spatiotemporal resolution, maximal recording depth, signal-to-noise ratio, etc.). In this article, we show that the new functional ultrasound (fUS) imaging technique is appropriate to record and map brain activity in awake primates on a scale previously unreachable. It allows distinguishing patterns similar to ocular dominance bands in the visual cortex through all layers of the cortex, which was impossible before with common techniques. This paper demonstrates the utility of fUS imaging for studying brain activity in awake primates and its interest to all neuroscientists., Deep regions of the brain are not easily accessible to investigation at the mesoscale level in awake animals or humans. We have recently developed a functional ultrasound (fUS) technique that enables imaging hemodynamic responses to visual tasks. Using fUS imaging on two awake nonhuman primates performing a passive fixation task, we constructed retinotopic maps at depth in the visual cortex (V1, V2, and V3) in the calcarine and lunate sulci. The maps could be acquired in a single-hour session with relatively few presentations of the stimuli. The spatial resolution of the technology is illustrated by mapping patterns similar to ocular dominance (OD) columns within superficial and deep layers of the primary visual cortex. These acquisitions using fUS suggested that OD selectivity is mostly present in layer IV but with extensions into layers II/III and V. This imaging technology provides a new mesoscale approach to the mapping of brain activity at high spatiotemporal resolution in awake subjects within the whole depth of the cortex.

Inherited retinal degenerations (IRDs) represent a diverse group of progressive, visually debilitating diseases that can lead to blindness in which mutations in genes that are critical to retinal function lead to progressive photoreceptor cell death and associated vision loss. IRDs are genetically heterogeneous, with over 260 disease genes identified to date.1 The development of treatments and cures to modify the rate of disease progression has been limited to date, with some success of neurotrophic factor therapy and gene therapies reported from clinical trials.2–11 The best example of treatment success is gene augmentation therapy for IRD caused by mutations in the RPE65 gene, which recently received US Food and Drug Administration (FDA) approval, which in fact represented the first FDA-approved gene therapy (GT) for any genetically inherited disease.4–9 Recent developments in the IRD field have advanced understanding of the mechanisms responsible for vision loss, creating new opportunities to intervene in the course of disease by developing new therapeutic approaches. In 2013, a Delphi-style gathering of IRD experts led to the identification, by consensus, of top priorities to advance therapeutic efforts for IRDs, including the need for systematic genotyping, improved standardization of visual function testing, development of more rigorous and widespread data collection protocols, and increased data sharing.12 This document summarizes more recent advances in the IRD field and outlines specific knowledge gaps. These knowledge gaps present opportunities for further investigation to enable development of therapies that may slow down or prevent vision loss, or restore vision, in affected patients. Atrophic age-related macular degeneration (AMD) is included among the target inherited retinal diseases of interest because first, understanding AMD may contribute to understanding of inherited macular diseases, and second, understanding of the genetics and mechanism of inherited macular degenerations may contribute to understanding of AMD.

International audience; No abstract available

International audience; Retinal degenerative diseases are a leading cause of irreversible blindness. Retinal cell death is the main cause of vision loss in genetic disorders such as retinitis pigmentosa, Stargardt disease and Leber congenital amaurosis, as well as in complex age-related diseases such as age-related macular degeneration (AMD). For these blinding conditions, gene and cell therapy approaches offer therapeutic intervention at various disease stages. The present review outlines recent advances in therapies for retinal degenerative disease, focusing on the progress and challenges in the development and clinical translation of gene and cell therapies. A significant body of preclinical evidence and initial clinical results pave the way for further development of these cutting edge treatments for patients with retinal degenerative disorders.

International audience; The rod-derived cone viability factors, RdCVF and RdCVF2, have potential therapeutical interests for the treatment of inherited photoreceptor degenerations. In the mouse lacking Nxnl2, the gene encoding RdCVF2, the progressive decline of the visual performance of the cones in parallel with their degeneration, arises due to the loss of trophic support from RdCVF2. In contrary, the progressive loss of rod visual function of the Nxnl2-/- mouse results from a decrease in outer segment length, mediated by a cell autonomous mechanism involving the putative thioredoxin protein RdCVF2L, the second spliced product of the Nxnl2 gene. This novel signaling mechanism extends to olfaction as shown by the progressive impairment of olfaction in aged Nxnl2-/- mice and the protection of olfactory neurons by RdCVF2. This study shows that Nxnl2 is a bi-functional gene involved in the maintenance of both the function and the viability of sensory neurons.

To the Editor: “Poppers” (slang for various forms of alkyl nitrite) are volatile nitric oxide donors that have been used for decades as recreational drugs. Both the popularity of and legal toleranc...

PMCID: PMC3293109.-- et. al., Mutations in the CRB1 gene are associated with variable phenotypes of severe retinal dystrophies, ranging from leber congenital amaurosis (LCA) to rod–cone dystrophy, also called retinitis pigmentosa (RP). Moreover, retinal dystrophies resulting from CRB1 mutations may be accompanied by specific fundus features: preservation of the para-arteriolar retinal pigment epithelium (PPRPE) and retinal telangiectasia with exudation (also referred to as Coats-like vasculopathy). In this publication, we report seven novel mutations and classify over 150 reported CRB1 sequence variants that were found in more that 240 patients. The data from previous reports were used to analyze a potential correlation between CRB1 variants and the clinical features of respective patients. This meta-analysis suggests that the differential phenotype of patients with CRB1 mutations is due to additional modifying factors rather than particular mutant allele combination. Hum Mutat 33:306–315, 2012. © 2011 Wiley Periodicals, Inc., The project was financially supported by the Foundation Fighting Blindness (I.A. FFB Grant No: CD-CL-0808-0466-CHNO and the CIC503 recognized as an FFB center, FFB Grant No: C-CMM-0907-0428-INSERM04), Agence Nationale de la Recherche (SSB), Fondation Voir et Entendre (CZ), GIS-maladies rares (CZ), Ville de Paris and Région Ile de France, National Institutes of Health (USA) (KB NIH, Grant No: 1R01EY020902 - 01A1). European Reintegration Grant PERG04-GA-2008-231125 (to K.B.).

International audience; Rod-cone dystrophies (RP) are a clinically and genetically heterogeneous group of inherited retinal disorders characterized by photoreceptor degeneration. RP1 is a major gene underlying autosomal dominant (ad) RP though prevalence figures vary depending on the origin of the cases from 0%-10% of all adRP. Some mutations in RP1 also lead to autosomal recessive RP. Herein we review all previously reported and several novel RP1 mutations in relation to the associated phenotype in patients from a French adRP cohort. Prevalence studies from this cohort show that 5.3% of the cases have RP1 mutations. This is in accordance with other studies reported from UK and USA. The majority of mutations represent truncating mutations which are located in a hot spot region of the gene. Similarly, we identified in total four novel deletions and nonsense mutations, of which two may represent recurrent mutations in this population. In addition a novel missense mutation of uncertain pathogenicity was identified. Including our findings, to date 43 RP1 mutations are known to cause adRP. Variable penetrance of the disease was observed in our and other cohorts. Most patients with RP1 mutations show classical signs of RP with relatively preserved central vision and visual field. ©2011 Wiley Periodicals, Inc.

International audience; BACKGROUND: Retinal detachment often leads to a severe and permanent loss of vision and its therapeutic management remains to this day exclusively surgical. We have used surgical specimens to perform a differential analysis of the transcriptome of human retinal tissues following detachment in order to identify new potential pharmacological targets that could be used in combination with surgery to further improve final outcome. METHODOLOGY/PRINCIPAL FINDINGS: Statistical analysis reveals major involvement of the immune response in the disease. Interestingly, using a novel approach relying on coordinated expression, the interindividual variation was monitored to unravel a second crucial aspect of the pathological process: the death of photoreceptor cells. Within the genes identified, the expression of the major histocompatibility complex I gene HLA-C enables diagnosis of the disease, while PKD2L1 and SLCO4A1 -which are both down-regulated- act synergistically to provide an estimate of the duration of the retinal detachment process. Our analysis thus reveals the two complementary cellular and molecular aspects linked to retinal detachment: an immune response and the degeneration of photoreceptor cells. We also reveal that the human specimens have a higher clinical value as compared to artificial models that point to IL6 and oxidative stress, not implicated in the surgical specimens studied here. CONCLUSIONS/SIGNIFICANCE: This systematic analysis confirmed the occurrence of both neurodegeneration and inflammation during retinal detachment, and further identifies precisely the modification of expression of the different genes implicated in these two phenomena. Our data henceforth give a new insight into the disease process and provide a rationale for therapeutic strategies aimed at limiting inflammation and photoreceptor damage associated with retinal detachment and, in turn, improving visual prognosis after retinal surgery.

International audience; Evaluating individual research performance is a complex task that ideally examines productivity, scientific impact, and research quality-a task that metrics alone have been unable to achieve. In January 2011, the French Academy of Sciences published a report on current bibliometric (citation metric) methods for evaluating individual researchers, as well as recommendations for the integration of quality assessment. Here, I draw on key issues raised by this report and comment on the suggestions for improving existing research evaluation practices.

This study was funded in part by grants from Alcon, Retina France and the Institut Carnot. M.P. is the recipient of a contract “Interface” from INSERM.; International audience; Microglial cells (MCs) are active sensors and reactive phagocytes of neural tissues. They are known to migrate and accumulate in areas of neuronal damage. Thus, microglial locomotion is an essential feature of the inflammatory reaction in neural tissue. Yet, to our knowledge there has been no report of direct in vivo observation of the migration of MCs. Here, we show that intravitreally injected cyanine dyes (DiO, DiI, and indocyanine green) are sequestrated in MCs during several months, and subsequently in vivo images of these fluorescent MCs can be obtained by confocal scanning laser ophthalmoscopy. This enabled noninvasive, time-lapse observation of the migrating behavior of MCs, both in the basal state and following laser damage. In the basal state, a slow, intermittent, random-like locomotion was observed. Following focal laser damage, MCs promptly (i.e., within 1 h) initiated centripetal, convergent migration. MCs up to 400 μm away migrated into the scar at velocities up to 7 μm/min. This early phase of centripetal migration was followed by a more prolonged phase of nontargeted locomotion around and within injured sites during at least 24 h. Cyanine-positive cells persisted within the scar during several weeks. To our knowledge, this is the first in vivo observation of the locomotion of individual MCs. Our results show that the locomotion of MCs is not limited to translocation to acutely damaged area, but may also be observed in the basal state and after completion of the recruitment of MCs into scars.

To comprehend the current challenges that French ophthalmic care is facing, one has first to appreciate the system and the changes that have occurred over the years leading to the current situation. French ophthalmic care is organized differently from its British and American counterparts and resembles its European neighbors. It follows a basic principle of the French medical practice which should guarantee a strict separation of medical care and prescription from commercial sales. Ophthalmologists and orthoptists, provide care to a patient, on one hand. Pharmacists and opticians on the other hand, enter commercial transactions with a client. The ophthalmologist is the center of the ophthalmic care, performing regular ophthalmic examination, prescribing glasses, contact lenses and supervising their tolerance, as well as performing ophthalmic surgery. The French ophthalmologist works closely in relation with orthoptists who can provide additional examinations, such as visual field tests, strabismus or low vision aid rehabilitation and opticians who provide glasses and contact lenses upon medical prescription. French patients are free to choose their practitioner and the National Health Insurance, la Securite Sociale, covers about 70 to 80% of the ophthalmologists and orthoptists fees whereas fees for optics and even more for low vision aid devices have never been well reimbursed and would be covered by optional private insurances. During recent years, optometrists have been trained through schools of optics and masters delivered by 2 scientific universities. However, their status is not well defined by the Health authorities, their potential fees for private consultations resulting in glasses prescription and delivery would not be covered by the National Health Insurance and their role in the scheme of French eye care is a recurrent and often passionate matter of debate. The number of practicing ophthalmologists in France is currently estimated at about 5300 (5354 from the last census reported in 2009 by the French national medical council1). This number has been stable over the past 15 years. Thus, for a general population reaching nearly 63 million, there are fewer than 9 ophthalmologists for 100 000 inhabitants, similar to Germany but lower than other European countries such as Belgium and Czech Republic (10 per 100 000), Italy and Spain (12 per 100 000) or Greece (14 per 100 000).3 Among practicing ophthalmologists, 43.5% are women. In comparison, 38.8% of all medical doctors are female. This percentage is even higher for the age range below 55, corresponding to the feminization of the medical profession.3 About 61% of practicing ophthalmologists are working only in private practice which is usually organized between a private office for ophthalmic examinations and a private clinic for surgical sessions.1 The distribution of these private practitioners across France is not uniform with a higher concentration in metropolitan areas, the Parisian region and the South of France and a real scarcity in rural areas and in Northern France. For the past 15 years, especially in metropolitan areas, the traditional model of a single-ophthalmologist private setting has largely been replaced by practices of 3 or more ophthalmologists, with often complementary expertise, who can appoint a secretary, an accountant, orthoptists and nurses. Some of these offices are equipped with the state-of-the art imaging techniques, visual field testing and even with visual electrophysiology. Group practices create a more favorable financial environment for purchase of modern and expensive equipment. Private offices seldom provide space for outpatient surgery. However, some practices can provide laser treatment, as well as, suitable facilities for photodynamic therapy or intravitreal injections. Such settings provide efficient care competing with public services with often dynamic medical discussions within and around the group similar to teaching hospitals, with the only additional pressure of productivity to repay loans contracted for equipment purchase. Aside from the 61% in private practice, an additional 13% are employed either by small private health centers or public hospitals, including academic centers.1 Moreover, 26% of practicing ophthalmologists work both in private and public practice, often keeping one or 2 clinical or surgical sessions in the hospital where they have been trained.1 The average age of practicing ophthalmologists is 49, with fewer ophthalmologists below 45 than above 55, reflecting the progressive aging of the ophthalmic population and rising concerns for the next 10 to 20 years.3 As the current group of practicing ophthalmologist retires, the number of graduating ophthalmologists each year, which is currently around 80, will not be sufficient to replace retirement and will increased disparity in care coverage, especially in the more sparsely populated areas of France. In fact, the number of ophthalmologist would decrease by 35% during the next 15 years.4 This projection applies not only to ophthalmologists but also to other specialists such as dermatologists and even to general practitioners. Reasons given for this situation include the selective access established in the 1970s to enter medical school and subsequently to enroll in a residency program in the 1980s, resulting in a 50% decrease of ophthalmologists trained per year. On the other hand, ophthalmology faces challenges generated by the increase of the French population, its aging and also the need to implement novel techniques and treatments as well as to establish a workable plan of preventive medicine. Many professionals have rung the alarm for more than 20 years including the National Union of French Ophthalmologists which has been very active in surveying practitioners, promoting debate and proposing solutions to avoid a critical situation.5, 6 Solutions are currently implemented to face the shortage in ophthalmologists and maintain an up-to-date standard of care, with free access to all. The obvious measure has been to gradually increase the number of trained ophthalmologist per year. Ideally, doubling this number within 5 years would ensure an appropriate replacement for retirement and this would only represent an additional 1.5 residents trained per year for each university center.5 Emphasis is also given on improving surgical training with a plan to add a year to ophthalmology residency, passing it from 4 to 5 years. This measure would ensure a sufficient number of well-trained ophthalmic surgeons to serve the additional load of cataract surgery generated by aging of the population. In addition, despite the absence of postgraduate recertification in France, the health ministry has implemented a mandatory requirement for post-university training in 2001.7,8 Furthermore, the French Ophthalmology Society with the National Union of French Ophthalmologists have produced guidelines on good ophthalmological practice, procedures and example of informed consent forms for special ophthalmic procedures.9,10 Although these documents have no legal standing, they are valuable in informing and helping ophthalmologists to keep an up-to-date practice. To ensure better geographical distribution of care, local initiatives have been proposed and encouraged. Some local authorities are providing free office space, surgical facilities as well as facilitating housing and support for young ophthalmologists. In addition, a new status of replacing practitioner, medecin remplacant, is created to encourage mobility for ophthalmologists unwilling to establish a permanent practice and flexible enough to adapt their activities toward available locum work. Furthermore, well-qualified ophthalmologists from other European countries with no shortage of ophthalmologists have been encouraged to come and practice in France. Along with increasing the number of ophthalmologists, the other efforts has been to increase the training and recruitment of orthoptists, the “historical partners” of French ophthalmologists and increase the number of tasks that could be delegated to them under medical supervision.11 For the vast majority of French ophthalmologists, this would be the best solution and more logical than introducing a new partner, the optometrist, within the French ophthalmic landscape. In addition, further efforts have been made to reinforce cooperation between the public and private sector and encourage the creation of health networks oriented toward preventive medicine with the help of telemedicine and mobile ophthalmic units. In collaboration with local ophthalmologists and often at their initiative, campaigns have been organized to improve early diagnosis of glaucoma, diabetic retinopathy, AMD and child amblyopia. Such campaigns are particularly relevant in regions with low ophthalmic coverage. With the aging of the population and the increase of AMD prevalence, efforts are also given to low vision aid rehabilitation. Orthoptists and opticians would be major players in these efforts. The future will reveal if these measures will be sufficient to fulfill the overall objectives of eye care in France: to ensure an available and transparent system for the patient, to provide ethical care free from conflict of interest, to create an efficient prevention strategy within a coherent public health system, and to moderate the economic cost for the best coverage of entire population.

International audience; BACKGROUND: RdCVF and RdCVF2, encoded by the nucleoredoxin-like genes NXNL1 and NXNL2, are trophic factors with therapeutic potential that are involved in cone photoreceptor survival. Studying how their expression is regulated in the retina has implications for understanding both their activity and the mechanisms determining cell-type specificity within the retina. METHODOLOGY/PRINCIPAL FINDINGS: In order to define and characterize their promoters, a series of luciferase/GFP reporter constructs that contain various fragments of the 5'-upstream region of each gene, both murine and human, were tested in photoreceptor-like and non-photoreceptor cell lines and also in a biologically more relevant mouse retinal explant system. For NXNL1, 5'-deletion analysis identified the human -205/+57 bp and murine -351/+51 bp regions as having promoter activity. Moreover, in the retinal explants these constructs drove expression specifically to photoreceptor cells. For NXNL2, the human -393/+27 bp and murine -195/+70 bp regions were found to be sufficient for promoter activity. However, despite the fact that endogenous NXNL2 expression is photoreceptor-specific within the retina, neither of these DNA sequences nor larger upstream regions demonstrated photoreceptor-specific expression. Further analysis showed that a 79 bp NXNL2 positive regulatory sequence (-393 to 315 bp) combined with a 134 bp inactive minimal NXNL1 promoter fragment (-77 to +57 bp) was able to drive photoreceptor-specific expression, suggesting that the minimal NXNL1 fragment contains latent elements that encode cell-type specificity. Finally, based on bioinformatic analysis that suggested the importance of a CRX binding site within the minimal NXNL1 fragment, we found by mutation analysis that, depending on the context, the CRX site can play a dual role. CONCLUSIONS/SIGNIFICANCE: The regulation of the Nucleoredoxin-like genes involves a CRX responsive element that can act as both as a positive regulator of promoter activity and as a modulator of cell-type specificity.

International audience; Rod-derived cone viability factor (RdCVF) is a thioredoxin-like protein, which has therapeutic potential for rod-cone dystrophies such as retinitis pigmentosa (RP). Cone loss in rodent models of RP is effectively reduced by RdCVF treatment. In this study, we investigate the physiological role of RdCVF in the retina by analyzing the phenotype of the mouse lacking the RdCVF gene, Nxnl1. Although the mice do not show an obvious developmental defect, an age-related reduction of both cone and rod function and a delay in the dark-adaptation of the retina are recorded by electroretinogram (ERG). This functional change is accompanied by a 17% reduction in cone density and a 20% reduction in thickness of the outer nuclear layer. The transcriptome of the retina reveals early changes in the expression of genes involved in programmed cell death, stress-response and redox-signaling, which is followed by a generalized injury response with increased microglial activation, GFAP, FGF2 and lipid peroxidation levels. Furthermore, cones of the mice lacking Nxnl1 are more sensitive to oxidative stress with a reduction of 65% in the cone flicker ERG amplitude measured under hyperoxic conditions. We show here that the RdCVF gene, in addition to therapeutic properties, has an essential role in photoreceptor maintenance and resistance to retinal oxidative stress.

Let There Be Light Retinitis pigmentosa, a disease that can result from a wide variety of genetic defects, causes degeneration of photoreceptor cells in the retina and leads to blindness. In the course of the disease, it is generally the rod photoreceptor cells that degenerate first. Cone photoreceptor cells may persist, but in a damaged and nonfunctional state. Busskamp et al. (p. 413 , published online 24 June; see the cover; see the Perspective by Cepko ) have now applied a gene therapy approach to mouse models of retinitis pigmentosa. Inducing expression of a bacterial light-activated ion pump, halorho dopsin, in the damaged cone cells improved visual responses in the diseased mouse retinas. Thus, it may be possible to rescue cone photoreceptors therapeutically, even after they have already been damaged.

International audience; The identification of one mechanism that causes vision loss in inherited degenerative retinal disorders revealed a new signaling molecule that represents a potential therapy for these currently untreatable diseases. This protein, called rod-derived cone viability factor (RdCVF), maintains the function and consequently the viability of cone photoreceptor cells in the retina; mice that lack this factor exhibit a progressive loss of photoreceptor cells. The gene encoding RdCVF also encodes, by differential splicing, a second product that has characteristics of a thioredoxin-like enzyme and protects both photoreceptor cells and, more specifically, its interacting protein partner, the tau protein, against oxidative damage. This signaling pathway potentially links environmental insults to an endogenous neuroprotective response.

International audience; Rod-derived Cone Viability Factor (RdCVF) is a trophic factor with therapeutic potential for the treatment of retinitis pigmentosa, a retinal disease that commonly results in blindness. RdCVF is encoded by Nucleoredoxin-like 1 (Nxnl1), a gene homologous with the family of thioredoxins that participate in the defense against oxidative stress. RdCVF expression is lost after rod degeneration in the first phase of retinitis pigmentosa, and this loss has been implicated in the more clinically significant secondary cone degeneration that often occurs. Here, we describe a study of the Nxnl1 promoter using an approach that combines promoter and transcriptomic analysis. By transfection of selected candidate transcription factors, chosen based upon their expression pattern, we identified the homeodomain proteins CHX10/VSX2, VSX1 and PAX4, as well as the zinc finger protein SP3, as factors that can stimulate both the mouse and human Nxnl1 promoter. In addition, CHX10/VSX2 binds to the Nxnl1 promoter in vivo. Since CHX10/VSX2 is expressed predominantly in the inner retina, this finding motivated us to demonstrate that RdCVF is expressed in the inner as well as the outer retina. Interestingly, the loss of rods in the rd1 mouse, a model of retinitis pigmentosa, is associated with decreased expression of RdCVF by inner retinal cells as well as by rods. Based upon these results, we propose an alternative therapeutic strategy aimed at recapitulating RdCVF expression in the inner retina, where cell loss is not significant, to prevent secondary cone death and central vision loss in patients suffering from retinitis pigmentosa.

International audience; In retinitis pigmentosa (RP), a majority of causative mutations affect genes solely expressed in rods; however, cone degeneration inevitably follows rod cell loss. Following transplantation and in vitro studies, we demonstrated the role of photoreceptor cell paracrine interactions and identified a Rod-derived Cone Viability Factor (RdCVF), which increases cone survival. In order to establish the clinical relevance of such mechanism, we assessed the functional benefit afforded by the injection of this factor in a frequent type of rhodopsin mutation, the P23H rat. In this model of autosomal dominant RP, RdCVF expression decreases in parallel with primary rod degeneration, which is followed by cone loss. RdCVF protein injections induced an increase in cone cell number and, more important, a further increase in the corresponding electroretinogram (ERG). These results indicate that RdCVF can not only rescue cones but also preserve significantly their function. Interestingly, the higher amplitude of the functional versus the survival effect of RdCVF on cones indicates that RdCVF is acting more directly on cone function. The demonstration at the functional level of the therapeutic potential of RdCVF in the most frequent of dominant RP mutations paves the way toward the use of RdCVF for preserving central vision in many RP patients.

Rod-cone dystrophies, also called retinitis pigmentosa (RP), are a clinically and genetically heterogeneous group of inherited retinal disorders primarily affecting rods with secondary cone degeneration 1. RP patients initially often complain of night blindness. This is attributed to the primarily affected rods and clinical sign of the impaired rod function. Later on, when the secondary cone dysfunctions manifests, progressive visual field constriction, abnormal color vision and loss of central vision can be observed – signs of decreasing cone function. As the disease progresses and retinal dysfunction decreases, visual impairment increases: in some cases the disease may eventually result in very severe visual impairment or even blindness. RP is the most common inherited form of severe retinal degeneration, with a frequency of about 1 in 4000 births and more than 1 million affected individuals over the world. The mode of inheritance can be X-linked (5–15%) autosomal dominant (30–40%) or autosomal recessive (50–60%) The remaining patients represent isolated cases of which the inheritance trait can not be established 1. To date, 20 autosomal dominant RP (adRP) genes have been reported (http://www.sph.uth.tmc.edu/Retnet/). One of the major genes underlying this disorder is rhodopsin (RHO) coding for the light absorbing molecule that initiates the signal transmission cascade in rod photoreceptors. According to the literature, RHO mutation prevalence ranges from 0 to 50% cases of adRP in cohorts from various geographical origins, with higher numbers reported in the United States 2–18. The genetic and phenotypic heterogeneity is not only found in RP in general but also specifically reflected in adRP with RHO mutations: Over 120 mutations have been identified in different sites of the gene including specific hot spots (http://www.sph.uth.tmc.edu/Retnet/, http://www.hgmd.cf.ac.uk/ac/all.php, http://www.retina-international.org/sci-news/rhomut.htm) 19. Certain mutations in RHO lead to diffuse rod-cone dysfunction whereas other cases are implicated in a more restricted disease that may predominate in the inferior part of the retina such as in sector RP 20. Phenotypic classifications have been proposed to reflect this variability. In particular, Cideciyan and co-workers have distinguished two classes of disease expression with allele-specificity 21: class A mutants show severely generalized abnormal rod function early in life with a constant rate of cone disease progression across the retina with time. Class B mutants show more restricted disease and absent or lateonset night blindness. Other classifications have been proposed based on the underlying pathogenic mechanism involved in adRP due to RHO mutations. Mendes and co-workers classified the different types of mutations in 6 groups. Class I refers exclusively to rhodopsin mutations that fold correctly but are not transported to the outer segment. Class II, refers to mutations that misfold, are retained in the endopasmic reticulum (ER) and cannot easily reconstitute with 11-cis-retinal. Class III refers to mutations that affect endocytosis. Class IV mutations do not affect folding per se but might affect rhodopsin stability and posttranslational modification. Similarly, Class V mutations have no obvious folding defect but show an increased activation rate for transducin. Mutants that appear to fold correctly but lead to the constitutive activation of opsin in the absence of the chromophore and in the dark constitute Class VI. Other mutations with unclear biochemical or cellular defect, or uninvestigated defect were not classified 19. Our comprehensive study presented herein aim to investigate in detail a French adRP cohort coming from 2 different clinical centers, namely Quinze-Vingts hospital in Paris and the Centre Hospitalier Regional in Montpellier located in the south of France. We will present the prevalence of rhodopsin mutations in this cohort and show precise phenotype-genotype correlations. Novel mutations will be analyzed on its predicted pathogenic mechanism as well as frequently mutated sites will be presented as putative candidates for therapeutic approaches.