The neurobiology of nutraceuticals combined with light exposure, a case report in the course of retinal degeneration.

The present article presents a case report and discusses the neurobiology underlying the potential neuro-repair induced by combined administration of phytochemicals in a patient undergoing photo-bio-modulation (PBM), which improves anatomical and clinical abnormalities in the course of age-related macular degeneration (AMD). After combined treatments the patient with nutraceuticals and PBM had noticeable improvement of retinal tissue with excellent vision for her age and no worsening of corneal guttae, which was present at the time of diagnosis. The present treatment was tailored, based on translational evidence, to improve the autophagy pathway, which is a key determinant in the onset and progression of AMD. In fact, treatment with specific patterns of light exposure combined with specific phytochemicals, may synergize in improving the microanatomy of the retina by restoring its neurobiology. The combination of light exposure, at selective wavelengths, with the effects produced by the intake of specific phytochemicals to treat AMD is reported here as "Lugano Protocol". Such a clinical protocol represents an "in progress" development backed up by translational research. In fact, recent evidence indicates that, specific phytochemicals, when administered in combination may promote anatomical and functional integrity within the retina. These in turn synergize with analogous effects produced by specific wavelengths, when administered at specific time intervals. The synergism between specific light and combined phytochemicals is discussed at molecular level, where recent data indicate how these treatments, when delivered according to specific patterns, may enhance autophagy in the retina. The improvement of retinal morphology and visual acuity, observed in this case report is thoroughly discussed in the light of the key role of autophagy in regulating the integrity of the retinal epithelium. Despite exciting, and consistent with translational evidence, the clinical report of a disease modifying effect during AMD owns the inherent limit of a case report, which requires wide validation in large number of patients. The potential effectiveness of "Lugano protocol" may apply to other types of retinal degenerations, where common alterations in the autophagy pathway do occur. Thus, such a therapeutic approach may extend to a common late stage of retinal trans-synaptic degeneration, where maladaptive plasticity during several types of retinal degenerative disorders eventually converge.

[Vision restoration: science fiction or reality?] / Restauration de la vision: Science-fiction ou réalité ?

Visual prostheses aim at restoring useful vision to patients who have become blind. This useful vision should enable them to regain autonomy in society for navigation, face recognition or reading. Two retinal prostheses have already obtained market authorization for patients affected by retinal dystrophies while a new device is in clinical trials for patients affected by age-related macular degeneration. Various prostheses, in particular cortical prostheses, are currently in clinical trials for optic neuropathies (glaucoma). Optogenetic therapy, an alternative strategy, has now reached the stage of clinical trials at the retinal level while moving forward at the cortical level. Other innovating strategies have obtained proofs of concepts in rodents but require a further validation in large animals prior to their evaluation on patients. Restoring vision should therefore become a reality for many patients even if this vision will not be as extensive and perfect as natural vision.

TITLE: Restauration de la vision: Science-fiction ou réalité ? ABSTRACT: Les prothèses visuelles ont pour objet de redonner une vision utile aux patients devenus aveugles. Cette vision utile doit leur permettre de retrouver une autonomie dans la société pour leurs déplacements, la reconnaissance des visages ou la lecture. Plusieurs prothèses rétiniennes ont déjà obtenu l'autorisation de mise sur le marché pour les dystrophies rétiniennes alors qu'un nouveau dispositif est en essai clinique pour la dégénérescence maculaire liée à l'âge. D'autres prothèses, notamment corticales, sont en essai clinique pour les neuropathies optiques (glaucome). Des stratégies alternatives, comme la thérapie optogénétique, ont également atteint le stade des essais cliniques. D'autres ont été évaluées sur les rongeurs, attendant leur validation sur le gros animal. Revoir devrait donc prochainement devenir une réalité pour de nombreux patients, même si cette vision ne sera ni aussi étendue, ni aussi parfaite que la vision naturelle.

Noninvasive Electrical Stimulation Improves Photoreceptor Survival and Retinal Function in Mice with Inherited Photoreceptor Degeneration.

Purpose: Neurons carry electrical signals and communicate via electrical activities. The therapeutic potential of electrical stimulation (ES) for the nervous system, including the retina, through improvement of cell survival and function has been noted. Here we investigated the neuroprotective and regenerative potential of ES in a mouse model of inherited retinal degeneration. Methods: Rhodopsin-deficient (Rho-/-) mice received one or two sessions of transpalpebral ES or sham treatments for 7 consecutive days. Intraperitoneal injection of 5-ethynyl-2'-deoxyuridine was used to label proliferating cells. Weekly electroretinograms were performed to monitor retinal function. Retinal morphology, photoreceptor survival, and regeneration were evaluated in vivo using immunohistochemistry and genetic fate-mapping techniques. Müller cell (MC) cultures were employed to further define the optimal conditions of ES application. Results: Noninvasive transpalpebral ES in Rho-/- mice improved photoreceptor survival and electroretinography function in vivo. ES also triggered residential retinal progenitor-like cells such as MCs to reenter the cell cycle, possibly producing new photoreceptors, as shown by immunohistochemistry and genetic fate-mapping techniques. ES directly stimulated cell proliferation and the expression of progenitor cell markers in MC cultures, at least partially through bFGF signaling. Conclusions: Our study showed that transpalpebral ES improved photoreceptor survival and retinal function and induced the proliferation, probably photoreceptor regeneration, of MCs; this occurs via stimulation of the bFGF pathways. These results suggest the exciting possibility of applying noninvasive ES as a versatile tool for preventing photoreceptor loss and mobilizing endogenous progenitors for reversing vision loss in patients with photoreceptor degeneration.

Photobiomodulation Mediates Neuroprotection against Blue Light Induced Retinal Photoreceptor Degeneration.

Potent neuroprotective effects of photobiomodulation with 670 nm red light (RL) have been demonstrated in several models of retinal disease. RL improves mitochondrial metabolism, reduces retinal inflammation and oxidative cell stress, showing its ability to enhance visual function. However, the current knowledge is limited to the main hypothesis that the respiratory chain complex IV, cytochrome c oxidase, serves as the primary target of RL. Here, we demonstrate a comprehensive cellular, molecular, and functional characterization of neuroprotective effects of 670 nm RL and 810 nm near-infrared light (NIRL) on blue light damaged murine primary photoreceptors. We show that respiratory chain complexes I and II are additional PBM targets, besides complex IV, leading to enhanced mitochondrial energy metabolism. Accordingly, our study identified mitochondria related RL- and NIRL-triggered defense mechanisms promoting photoreceptor neuroprotection. The observed improvement of mitochondrial and extramitochondrial respiration in both inner and outer segments is linked with reduced oxidative stress including its cellular consequences and reduced mitochondria-induced apoptosis. Analysis of regulatory mechanisms using gene expression analysis identified upregulation α-crystallins that indicate enhanced production of proteins with protective functions that point to the rescued mitochondrial function. The results support the hypothesis that energy metabolism is a major target for retinal light therapy.

Metabolite therapy guided by liquid biopsy proteomics delays retinal neurodegeneration.

BACKGROUND: Neurodegenerative diseases are incurable disorders caused by progressive neuronal cell death. Retinitis pigmentosa (RP) is a blinding neurodegenerative disease that results in photoreceptor death and progresses to the loss of the entire retinal network. We previously found that proteomic analysis of the adjacent vitreous served as way to indirectly biopsy the retina and identify changes in the retinal proteome. METHODS: We analyzed protein expression in liquid vitreous biopsies from autosomal recessive (ar)RP patients with PDE6A mutations and arRP mice with Pde6ɑ mutations. Proteomic analysis of retina and vitreous samples identified molecular pathways affected at the onset of photoreceptor death. Based on affected molecular pathways, arRP mice were treated with a ketogenic diet or metabolites involved in fatty-acid synthesis, oxidative phosphorylation, and the tricarboxylic acid (TCA) cycle. FINDINGS: Dietary supplementation of a single metabolite, ɑ-ketoglutarate, increased docosahexaeonic acid levels, provided neuroprotection, and enhanced visual function in arRP mice. A ketogenic diet delayed photoreceptor cell loss, while vitamin B supplementation had a limited effect. Finally, desorption electrospray ionization mass spectrometry imaging (DESI-MSI) on ɑ-ketoglutarate-treated mice revealed restoration of metabolites that correlated with our proteomic findings: uridine, dihydrouridine, and thymidine (pyrimidine and purine metabolism), glutamine and glutamate (glutamine/glutamate conversion), and succinic and aconitic acid (TCA cycle). INTERPRETATION: This study demonstrates that replenishing TCA cycle metabolites via oral supplementation prolongs retinal function and provides a neuroprotective effect on the photoreceptor cells and inner retinal network. FUNDING: NIH grants [R01EY026682, R01EY024665, R01EY025225, R01EY024698, R21AG050437, P30EY026877, 5P30EY019007, R01EY018213, F30EYE027986, T32GM007337, 5P30CA013696], NSF grant CHE-1734082.

Brain-Derived Neurotrophic Factor as a Treatment Option for Retinal Degeneration.

This review discusses the therapeutic potential of brain-derived neurotrophic factor (BDNF) for retinal degeneration. BDNF, nerve growth factor (NGF), neurotrophin 3 (NT-3) and NT-4/NT-5 belong to the neurotrophin family. These neuronal modulators activate a common receptor and a specific tropomyosin-related kinase (Trk) receptor. BDNF was identified as a photoreceptor protectant in models of retinal degeneration as early as 1992. However, development of effective therapeutics that exploit this pathway has been difficult due to challenges in sustaining therapeutic levels in the retina.

670nm light treatment following retinal injury modulates Müller cell gliosis: Evidence from in vivo and in vitro stress models.

Photobiomodulation (PBM) with 670 nm light has been shown to accelerate wound healing in soft tissue injuries, and also to protect neuronal tissues. However, little data exist on its effects on the non-neuronal components of the retina, such as Müller cells (MCs), which are the principal macroglia of the retina that play a role in maintaining retinal homeostasis. The aim of this study was to explore the effects of 670 nm light on activated MCs using in vivo and in vitro stress models. Adult Sprague-Dawley rats were exposed to photo-oxidative damage (PD) for 24 h and treated with 670 nm light at 0, 3 and 14 days after PD. Tissue was collected at 30 days post-PD for analysis. Using the in vitro scratch model with a human MC line (MIO-M1), area coverage and cellular stress were analysed following treatment with 670 nm light. We showed that early treatment with 670 nm light after PD reduced MC activation, lowering the retinal expression of GFAP and FGF-2. 670 nm light treatment mitigated the production of MC-related pro-inflammatory cytokines (including IL-1ß), and reduced microglia/macrophage (MG/MΦ) recruitment into the outer retina following PD. This subsequently decreased photoreceptor loss, slowing the progression of retinal degeneration. In vitro, we showed that 670 nm light directly modulated MC activation, reducing rates of area coverage by suppressing cellular proliferation and spreading. This study indicates that 670 nm light treatment post-injury may have therapeutic benefit when administered shortly after retinal damage, and could be useful for retinal degenerations where MC gliosis is a feature of disease progression.

Intraperitoneal administration of adipose tissue-derived stem cells for the rescue of retinal degeneration in a mouse model via indigenous CNTF up-regulation by IL-6.

As the world's population begins to age, retinal degeneration is an increasing problem, and various treatment modalities are being developed. However, there have been no therapies for degenerative retinal conditions that are not characterized by neovascularization. We investigated whether transplantation of mouse adipose tissue-derived stem cells (mADSC) into the intraperitoneal space has a rescue effect on NaIO3 -induced retinal degeneration in mice. In this study, mADSC transplantation recovered visual function and preserved the retinal outer layer structure compared to the control group without any integration of mADSC into the retina. Moreover, endogenous ciliary neurotrophic factor (CNTF) was elevated in the retinas of mADSC-treated mice. We found that lipopolysaccharide (LPS) or LPS-stimulated monocyte supernatant induced the secretion of granulocyte colony stimulating factor (GCSF), CD54, CXCL10, interleukin-6 (IL-6), and CCL5 from the mADSC by cytokine array. Network inference was conducted to investigate signaling networks related to CNTF regulation. Based on bioinformatics data, the expression of IL-6 was related to the expression of CNTF. Additionally, intravitreal injection of IL-6 in rats produced up-regulation of endogenous CNTF in the retina. mADSC had a rescue effect on retinal degeneration through the up-regulation of endogenous CNTF by IL-6. Thus, transplantation of mADSC could be a potential treatment option for retinal degeneration.

Carbon nanotube electrodes for retinal implants: A study of structural and functional integration over time.

The choice of electrode material is of paramount importance in neural prosthetic devices. Electrodes must be biocompatible yet able to sustain repetitive current injections in a highly corrosive environment. We explored the suitability of carbon nanotube (CNT) electrodes to stimulate retinal ganglion cells (RGCs) in a mouse model of outer retinal degeneration. We investigated morphological changes at the bio-hybrid interface and changes in RGC responses to electrical stimulation following prolonged in vitro coupling to CNT electrodes. We observed gradual remodelling of the inner retina to incorporate CNT assemblies. Electrophysiological recordings demonstrate a progressive increase in coupling between RGCs and the CNT electrodes over three days, characterized by a gradual decrease in stimulation thresholds and increase in cellular recruitment. These results provide novel evidence for time-dependent formation of viable bio-hybrids between CNTs and the retina, demonstrating that CNTs are a promising material for inclusion in retinal prosthetic devices.

Red-shifted channelrhodopsin stimulation restores light responses in blind mice, macaque retina, and human retina.

Targeting the photosensitive ion channel channelrhodopsin-2 (ChR2) to the retinal circuitry downstream of photoreceptors holds promise in treating vision loss caused by retinal degeneration. However, the high intensity of blue light necessary to activate channelrhodopsin-2 exceeds the safety threshold of retinal illumination because of its strong potential to induce photochemical damage. In contrast, the damage potential of red-shifted light is vastly lower than that of blue light. Here, we show that a red-shifted channelrhodopsin (ReaChR), delivered by AAV injections in blind rd1 mice, enables restoration of light responses at the retinal, cortical, and behavioral levels, using orange light at intensities below the safety threshold for the human retina. We further show that postmortem macaque retinae infected with AAV-ReaChR can respond with spike trains to orange light at safe intensities. Finally, to directly address the question of translatability to human subjects, we demonstrate for the first time, AAV- and lentivirus-mediated optogenetic spike responses in ganglion cells of the postmortem human retina.

Whole-eye electrical stimulation therapy preserves visual function and structure in P23H-1 rats.

Low-level electrical stimulation to the eye has been shown to be neuroprotective against retinal degeneration in both human and animal subjects, using approaches such as subretinal implants and transcorneal electrical stimulation. In this study, we investigated the benefits of whole-eye electrical stimulation (WES) in a rodent model of retinitis pigmentosa. Transgenic rats with a P23H-1 rhodopsin mutation were treated with 30 min of low-level electrical stimulation (4 µA at 5 Hz; n = 10) or sham stimulation (Sham group; n = 15), twice per week, from 4 to 24 weeks of age. Retinal and visual functions were assessed every 4 weeks using electroretinography and optokinetic tracking, respectively. At the final time point, eyes were enucleated and processed for histology. Separate cohorts were stimulated once for 30 min, and retinal tissue harvested at 1 h and 24 h post-stimulation for real-time PCR detection of growth factors and inflammatory and apoptotic markers. At all time-points after treatment, WES-treated rat eyes exhibited significantly higher spatial frequency thresholds than untreated eyes. Inner retinal function, as measured by ERG oscillatory potentials (OPs), showed significantly improved OP amplitudes at 8 and 12 weeks post-WES compared to Sham eyes. Additionally, while photoreceptor segment and nuclei thicknesses in P23H-1 rats did not change between treatment groups, WES-treated eyes had significantly greater numbers of retinal ganglion cell nuclei than Sham eyes at 20 weeks post-WES. Gene expression levels of brain-derived neurotrophic factor (BDNF), caspase 3, fibroblast growth factor 2 (FGF2), and glutamine synthetase (GS) were significantly higher at 1 h, but not 24 h after WES treatment. Our findings suggest that WES has a beneficial effect on visual function in a rat model of retinal degeneration and that post-receptoral neurons may be particularly responsive to electrical stimulation therapy.

[Ocular electrical stimulation: Therapeutic application and active retinal implants for hereditary retinal degenerations]. / Okuläre elektrische Stimulation : Therapeutische Anwendung und aktive retinale Implantate bei hereditären Netzhautdegenerationen.

BACKGROUND: Electrical stimulation has a long history in ophthalmology. Subthreshold electrical stimulation can have beneficial therapeutic effects on hereditary degenerative retinal diseases. Suprathreshold stimulation is able to elicit visual perceptions and, if multielectrode fields are arranged as an array, usable pictures can be perceived by blind patients. OBJECTIVES: This is a review article on the current situation and studies on therapeutic transcorneal electrical stimulation. Moreover, the challenges, surgical concepts and visual results of active retinal implants are discussed. MATERIAL AND METHODS: This article gives an overview on transcorneal electrical stimulation and active retinal implants based on published results, with special emphasis on the clinical application. RESULTS: The results of initial controlled studies on therapeutic transcorneal electrical stimulation in hereditary retinal diseases were very promising. The largest controlled study so far in patients with retinitis pigmentosa (RP) has yielded many positive trends and some significant improvements in electrophysiological data. Currently, two retinal implants have regulatory approval, the Argus II retinal prosthesis system® (SecondSight®) and the Alpha-IMS© (Retina Implant AG). Both systems can be used to improve visual perception and under test conditions can achieve visual acuities of 0.02 and 0.04, respectively. CONCLUSION: In-depth analyses and follow-up studies in larger patient groups are currently planned to definitively clarify the potential of therapeutic transcorneal electrical stimulation in RP patients. The challenges of currently available active retinal implants are the technical biostability and the limited spatial resolution.

Achromatopsia: on the doorstep of a possible therapy.

Achromatopsia (ACHM) is a rare autosomal recessive inherited retinal disorder with an incidence of approximately 1 in 30,000. It presents at birth or early infancy and is typically characterized by reduced visual acuity, nystagmus, photophobia, and very poor or absent color vision. The symptoms arise from isolated cone dysfunction, which can be caused by mutations in the crucial components of the cone phototransduction cascade. Although ACHM is considered a functionally nonprogressive disease affecting only the cone system, recent studies have described progressive age-dependent changes in retinal architecture. Currently, no specific therapy is available for ACHM; however, gene replacement therapy performed on animal models for three ACHM genes has shown promising results. Accurate genetic and clinical diagnosis of patients may therefore enhance and enable therapeutic intervention in the near future. This short review summarizes the genetic background, pathophysiology, clinical findings, diagnostics, and therapeutic perspectives in ACHM.

The Status of RPE65 Gene Therapy Trials: Safety and Efficacy.

Several groups have reported the results of clinical trials of gene augmentation therapy for Leber congenital amaurosis (LCA) because of mutations in the RPE65 gene. These studies have used subretinal injection of adeno-associated virus (AAV) vectors to deliver the human RPE65 cDNA to the retinal pigment epithelial (RPE) cells of the treated eyes. In all of the studies reported to date, this approach has been shown to be both safe and effective. The successful clinical trials of gene augmentation therapy for retinal degeneration caused by mutations in the RPE65 gene sets the stage for broad application of gene therapy to treat retinal degenerative disorders.

The role of electrical stimulation therapy in ophthalmic diseases.

INTRODUCTION: Electrical stimulation therapy (EST) involves the use of a low-intensity electrical current in the treatment of neuromuscular conditions. During the recent two decades, EST has emerged as a potential neuroprotective strategy in certain ophthalmic diseases, aided by a lack of effective management for these conditions. PURPOSE: The aim of this review is to summarize and discuss current available evidence for the use of EST in ophthalmic diseases in the laboratory setting and in human trials. METHODS: The compilation and review of published English-language reports on the use of EST in human ophthalmic disease and animal models of ophthalmic disease. RESULTS: From published reports, research work on the use of EST in ophthalmic diseases began in the last 20 years. Different methods of electrical stimulation have been devised, with varying levels of invasiveness. Results from human trials have favored earlier and repeated treatment after insults to the optic nerve, while EST has shown transient effectiveness in degenerative diseases of photoreceptors. Patients also reported no serious adverse effects from EST in the clinical trials. Results from animal studies have further confirmed survival benefits of EST in retinal cell survival, with the underlying mechanism likely multifactorial, but involving Müller cell modulation. CONCLUSIONS: Results from human and animal studies have demonstrated the relevance and potential effectiveness of EST in ophthalmic disease. However, optimal disease and species-specific stimulation settings need to be defined.

[Current therapeutic approaches in inherited retinal degeneration: from genes to chip]. / Therapieansätze für erbliche Netzhauterkrankungen: von den Genen bis zum Chip.

Different strategies for the treatment of inherited photoreceptor degeneration are currently being investigated, with each of these approaches facing specific challenges. Gene therapy, for instance, may be feasible only for genetically well-defined pathologies. However, inherited retinal disorders are genetically highly heterogeneous and early onset disorders may restrict the therapeutic window. The majority of currently developed molecular approaches aim at the reconstitution of physiologically important functions in RPE and photoreceptor. Neuroprotection attempts to prolong cell survival and proper function via sustained delivery systems that fulfil a long-term dynamic reservoir function for therapeutic neuroprotective compounds. Cell-based approaches include replacement strategies such as cell transplantation, the implantation of prosthetic devices or optogenetics. They aim at replacing lost neurosensory functions of the retina. This short review aims at providing an insight into current therapeutic strategies and future treatment options for retinal disorders. Pharmacological and nutritional support strategies are only briefly discussed as we focus here on molecular and prosthetic therapeutic approaches.

Neuroprotective effects of low level electrical stimulation therapy on retinal degeneration.

Low-level electrical stimulation applied to the eye has been shown to have neuroprotective effects on photoreceptors and retinal ganglion cells. In this review, we compare the effects of Subretinal Electrical Stimulation (SES), Transcorneal Electrical Stimulation (TES), and Whole Eye Stimulation (WES) on preserving retinal structure and function, and visual acuity, in retinal degeneration. Similarities and differences in stimulus parameters, targeted cells and growth factor expression will be discussed with emphasis on studies that have translated laboratory findings into clinical trials.

Intravitreal silicon-based quantum dots as neuroprotective factors in a model of retinal photoreceptor degeneration.

PURPOSE: To study the intravitreal application of silicon quantum dots (QDs) and their capabilities to deliver electrical stimulation to the retinal cells and to assess the potential effect on retinal electrophysiology and anatomy. METHODS: A Royal College of Surgeon rat model of retinal degeneration was used in this study. A total of 32 eyes were used, divided in four groups of 8 eyes each; the first group received the silicon-based QD, the second group received an inactive gold-based QD, the third group received a sham injection, and the fourth group was used as a control. An electroretinogram (ERG) was done at baseline and thereafter every week for 9 weeks. At the end of the follow-up, eyes were collected for further pathologic analysis and nuclei cell counts. RESULTS: Eyes within the silicon-based QD group showed a definite but transient increase in the waves of the ERG, especially in the rod response compared with the sham and control groups (P < 0.05). The pathologic examination demonstrated a higher nuclei count in the QD group, consistent with a higher cell survival rate than that in the sham and control groups in which cells degenerated as expected. CONCLUSIONS: Intravitreal injection of silicon-based QD seems to be safe and well tolerated, with no evident toxic reaction and demonstrates a beneficial effect by prolonging cell survival rate and improving ERG patterns in a well-established model of retinal degeneration. (ClinicalTrials.gov numbers NCT00407602, NCT01490827.).