RDH12-associated retinal degeneration caused by a homozygous pathogenic variant of 146C>T and literature review

AIM:To describe the clinical,electrophysiological,and genetic features of an unusual case with an RDH12 homozygous pathogenic variant and reviewed the characteristics of the patients reported with the same variant.METHODS:The patient underwent a complete ophthalmologic examination including best-corrected visual acuity,anterior segment and dilated fundus,visual field,spectral-domain optical coherence tomography(OCT)and electroretinogram(ERG).The retinal disease panel genes were sequenced through chip capture high-throughput sequencing and Sanger sequencing was used to confirm the result.Then we reviewed the characteristics of the patients reported with the same variant.RESULTS:A 30-year male presented with severe early retinal degeneration who complained night blindness,decreased visual acuity,vitreous floaters and amaurosis fugax.The best corrected vision was 0.04 OD and 0.12 OS,respectively.The fundus photo and OCT showed bilateral macular atrophy but larger areas of macular atrophy in the left eye.Autofluorescence shows bilateral symmetrical hypo-autofluorescence.ERG revealed that the amplitudes of a-and b-wave were severely decreased.Multifocal ERG showed decreased amplitudes in the local macular area.A homozygous missense variant c.146C>T(chr14:68191267)was found.The clinical characteristics of a total of 13 patients reported with the same pathologic variant varied.CONCLUSION:An unusual patient with a homozygous pathogenic variant in the c.146C>T of RDH12 which causes late-onset and asymmetric retinal degeneration are reported.The clinical manifestations of the patient with multimodal retinal imaging and functional examinations have enriched our understanding of this disease.

Systemic epigallocatechin gallate protects against retinal degeneration and hepatic oxidative stress in the P23H-1 rat

Retinitis pigmentosa(RP) is a group of inherited retinal disorders that lead to photoreceptor loss.RP has been reported to be related to oxidative stress,autophagy,and inflammation.(-)-Epigallocatechin gallate(EGCG),the most abundant catechin-based flavonoid in green tea leaves,has significant antioxidant,anti-carcinogenic,antimicrobial,and neuroprotective properties.EGCG,given its low molecular weight and hydrophilic properties,can cross the blood-retinal barrier and is able to reach different ocular tissues such as the lens,cornea,and retina.EGCG has been shown to provide retinal protection against ischemia;sodium nitroprusside-,N-methyl-D-aspartate-,lipopolysaccharide-,light-,sodium iodate-,or H2 O2-induced damage and diabetic retinopathy.This suggests that systemic EGCG administration has the potential to protect against retinal degenerative or neurodegenerative diseases such as RP.The aim of this work was to investigate whether EGCG can protect against RP progression in the animal P23 H line 1,the model of RP.Albino P23 H rats were crossed with pigmented Long Evans rats to produce offspring exhibiting the clinical features of RP.Pigmented P23 H rats were treated via intraperitoneal injection with saline or EGCG at a dose of 25 mg/kg every week from P100 to P160 and then compared to wild-type Long Evans rats.Rats treated with EGCG showed better visual and retinal electrical function with increased contrast sensitivity and b-wave values compared with those observed in P23 H rats treated with vehicle.EGCG reduced lipid peroxidation and increased total antioxidant capacity and catalase and superoxide dismutase activities.No differences were observed in visual acuity,nitrate levels,nitrite levels or glutathione S-transferase activity.In conclusion,EGCG not only reduced the loss of visual function in P23 H rats but also improved the levels of antioxidant enzymes and reduced oxidative damage.This study was approved by the Institutional Animal Care and Use Committee(CEICA) from the University of Zaragoza under project license PI12/14 on July 11,2014.

Effect of rotary motion on Fos protein expression in the vestibular-related nucleus population in a mouse model of rapid retinal degeneration

BACKGROUND： Previous studies on integration mechanisms of visual and vestibular information in the central nervous system have focused on the vestibular system. Due to the lack of an appropriate animal model, few studies have addressed the visual system with regard to visual and vestibular information. OBJECTIVE： To investigate Fos protein expression differences of vestibular-related nucleus populations in a mouse model of rapid retinal degeneration and normal wild-type Kunming mice following rotary motion, and to verify integration regions of visual and vestibular information in the central nervous system. DESIGN, TIME AND SETTING： A randomized, controlled in vitro study was performed at the Key Laboratory of Aerospace Medicine of Ministry of Education, China from March 2008 to February 2009. MATERIALS： A rotary stimulation device was re-fit to an electric, rotating chair produced by the School of Aerospace Medicine, the Fourth Military Medical University. METHODS： A total of 12 rapid retinal degeneration mice and 12 normal wild-type male Kunming mice were randomly assigned to experimental and control subgroups, respectively （n = 6）. Mice in the experimental group were exposed to rotary motion at a speed of 180°/s, 3 minutes per cycle, in an alternating clockwise/counterclockwise movement. Mice in the control group were not exposed to rotary motion. MAIN OUTCOME MEASURES： Differences in the number of Fos-positive neurons were determined in the vestibular nucleus, prepositus hypoglossal nucleus, inferior olive subnucleus beta, Kooy cap of the inferior olive medial nucleus, and the flocculus and paraflocculus of the cerebellum in rapid retinal degeneration mice and normal wild-type Kunming mice. RESULTS： The number of Fos-positive neurons was reduced in the prepositus hypoglossal nucleus and the Kooy cap of the inferior olive medial nucleus in the rapid retinal degeneration mice following 30 minutes of rotary motion in the experimental group, compared with the normal wild-type Kunming mice （P 〈 0.01）. There was no significant difference in Fos protein expression in the vestibular nucleus, inferior olive subnucleus beta, and the flocculus and paraflocculus of the cerebellum between the rapid retinal degeneration mice and normal wild-type Kunming mice. CONCLUSION： Visual information affected neuronal activation in the prepositus hypoglossal nucleus and the Kooy cap of the inferior olive medial nucleus in mice following rotary motion. The prepositus hypoglossal nucleus and the dorsal cap of Kooy of inferior olive medial nucleus were shown to be key integration regions of visual information and vestibular information in the central nervous system.

Tweaking the immune system as an adjuvant for the treatment of retinal degenerations

Blinding diseases such as photoreceptor degenerations are debilitating conditions that severely impair daily lives of affected patients.This group of diseases are amenable to photoreceptor replacement therapies and recent transplantation studies provided proof-of-principle for functional recovery at the retinal and behavioral level,though the actual mechanism of repair still needs further investigations.The immune system responds in several ways upon photoreceptor engraftment,resulting in T-cell and macrophage infiltrations and,consequently,decrease in graft survival.Most studies on the role of the immune system suggest a detrimental effect in a therapeutic setting.Conversely,the opposite idea wherein the immune system can be activated towards a protective state was also explored in other experimental paradigms.Here,Neves and colleagues explored the potential of cross-species studies and,to a certain extent,the concept of a protective immune system in retinal degeneration and therapy.Mesencephalic astrocyte-derived neurotrophic factor(MANF)was identified in this study as a novel factor that,by modulating the immune system,can slow down photoreceptor degeneration and improve transplantation outcome.

NLRP3 and autophagy in retinal ganglion cell inflammation in age-related macular degeneration:potential therapeutic implications

Retinal degenerative diseases were a large group of diseases characterized by the primary death of retinal ganglion cells(RGCs).Recent studies had shown an interaction between autophagy and nucleotide-binding oligomerization domain-like receptor 3(NLRP3)inflammasomes,which may affect RGCs in retinal degenerative diseases.The NLRP3 inflammasome was a protein complex that,upon activation,produces caspase-1,mediating the apoptosis of retinal cells and promoting the occurrence and development of retinal degenerative diseases.Upregulated autophagy could inhibit NLRP3 inflammasome activation,while inhibited autophagy can promote NLRP3 inflammasome activation,which leaded to the accelerated emergence of drusen and lipofuscin deposition under the neurosensory retina.The activated NLRP3 inflammasome could further inhibit autophagy,thus forming a vicious cycle that accelerated the damage and death of RGCs.This review discussed the relationship between NLRP3 inflammasome and autophagy and its effects on RGCs in age-related macular degeneration,providing a new perspective and direction for the treatment of retinal diseases.

The roles of macrophage migration inhibitory factor in retinal diseases

Macrophage migration inhibitory factor(MIF),a multifunctional cytokine,is secreted by various cells and participates in inflammatory reactions,including innate and adaptive immunity.There are some evidences that MIF is involved in many vitreoretinal diseases.For example,MIF can exacerbate many types of uveitis;measurements of MIF levels can be used to monitor the effectiveness of uveitis treatment.MIF also alleviates trauma-induced and glaucoma-induced optic nerve damage.Furthermore,MIF is critical for retinal/choroidal neovascularization,especially complex neovascularization.MIF exacerbates retinal degeneration;thus,anti-MIF therapy may help to mitigate retinal degeneration.MIF protects uveal melanoma from attacks by natural killer cells.The mechanism underlying the effects of MIF in these diseases has been demonstrated:it binds to cluster of differentiation 74,inhibits the c-Jun N-terminal kinase pathway,and triggers mitogen-activated protein kinases,extracellular signal-regulated kinase-1/2,and the phosphoinositide-3-kinase/Akt pathway.MIF also upregulates Toll-like receptor 4 and activates the nuclear factor kappa-B signaling pathway.This review focuses on the structure and function of MIF and its receptors,including the effects of MIF on uveal inflammation,retinal degeneration,optic neuropathy,retinal/choroidal neovascularization,and uveal melanoma.

Contribution of Borneolum syntheticum to the Intervention Effect of Liuwei Dihuang Pill (六味地黄丸) on Experimental Retinal Degeneration

Objective： To observe the contribution of Borneolum syntheticum to the intervention effect of Liuwei Dihuang Pill （六味地黄丸, LDP） on experimental retinal degeneration, and initially investigate the mechanism of Borneolum syntheticum as meridian-lead-in drug. Methods： A total of 180 sodium iodate- induced retinital degeneration rats were randomly divided into three groups, including distilled water group, LDP group, and LDP＋Borneolum syntheticum （LDP＋BS） group. Twenty normal rats were fed regularly without any treatment as normal control. On day 7 and 14 after treatment, histopathological study and transferase-mediated deoxyuridine triphosphate-biotin nick end labeling （TUNEL） test were performed to evaluate the retinopathy. Claudin-5 expression at blood-retina barrier （BRB） was detected by Western blot at different time points from 0.5 to 8 h after gavage. Results： On day 7 and 14 after treatment, the retinal lesion grades were significantly different among the three groups （P〈0.05）. The grade in the LDP＋BS group was significantly less than the LDP and distilled water groups （both P〈0.05）, no significant difference was observed between the LDP and distilled water groups （P〉0.05）. The apoptosis rates in the LDP＋BS group was significantly less than the distilled water and LDP groups （both P〈0.05）, while there was no significant difference between LDP and distilled water groups （P〉0.05）. Expression of claudin-5 in LDP＋BS group was significantly less than the other two groups at 0.5, 1 and 2 h after gavage （P〈0.05）. There was no apparent difference among the three groups at 4 and 8 h after gavage （P〉0.05）. Conclusion： Bomeolum syntheticum could strengthen the effect of LDP on experimental retinal degeneration, indicated that Bomeolum syntheticum might play the role of meridian-lead-in drug in the formula. The mechanism may be due to Bomeolum syntheticum could promote the physiologically openness of blood- retina barrier through transiently affecting the expression of claudin-5.

Inflammation and retinal degenerative diseases

Vision is an ability that depends on the precise structure and functioning of the retina.Any kind of stress or injury can disrupt the retinal architecture and leads to vision impairment,vision loss,and blindness.Immune system and immune response function maintain homeostasis in the microenvironment.Several genetic,metabolic,and environmental factors may alter retinal homeostasis,and these events may initiate various inflammatory cascades.The prolonged inflammatory state may contribute to the initiation and development of retinal disorders such as glaucoma,age-related macular degeneration,diabetic retinopathy,and retinitis pigmentosa,which pose a threat to vision.In the current review,we attempted to provide sufficient evidence on the role of inflammation in these retinal disorders.Moreover,this review paves the way to focus on therapeutic targets of the disease,which are found to be promising.

Overexpressing NeuroD1 reprograms Müller cells into various types of retinal neurons

The onset of retinal degenerative disease is often associated with neuronal loss. Therefore, how to regenerate new neurons to restore vision is an important issue. NeuroD1 is a neural transcription factor with the ability to reprogram brain astrocytes into neurons in vivo. Here, we demonstrate that in adult mice, NeuroD1 can reprogram Müller cells, the principal glial cell type in the retina, to become retinal neurons. Most strikingly, ectopic expression of NeuroD1 using two different viral vectors converted Müller cells into different cell types. Specifically, AAV7 m8 GFAP681::GFP-ND1 converted Müller cells into inner retinal neurons, including amacrine cells and ganglion cells. In contrast, AAV9 GFAP104::ND1-GFP converted Müller cells into outer retinal neurons such as photoreceptors and horizontal cells, with higher conversion efficiency. Furthermore, we demonstrate that Müller cell conversion induced by AAV9 GFAP104::ND1-GFP displayed clear dose-and time-dependence. These results indicate that Müller cells in adult mice are highly plastic and can be reprogrammed into various subtypes of retinal neurons.

Neural and Müller glial adaptation of the retina to photoreceptor degeneration

The majority of inherited retinal degenerative diseases and dry age-related macular degeneration are characterized by decay of the outer retina and photoreceptors,which leads to progressive loss of vision.The inner retina,including second-and third-order retinal neurons,also shows aberrant structural changes at all stages of degeneration.Müller glia,the major glial cells maintain retinal homeostasis,activating and rearranging immediately in response to photoreceptor stress.These phenomena are collectively known as retinal remodeling and are anatomically well described,but their impact on visual function is less well characterized.Retinal remodeling has traditionally been considered a detrimental chain of events that decreases visual function.However,emerging evidence from functional assays suggests that remodeling could also be a part of a survival mechanism wherein the inner retina responds plastically to outer retinal degeneration.The visual system’s first synapses between the photoreceptors and bipolar cells undergo rewiring and functionally compensate to maintain normal signal output to the brain.Distinct classes of retinal ganglion cells remain even after the massive loss of photoreceptors.Müller glia possess the regenerative potential for retinal recovery and possibly exert adaptive transcriptional changes in response to neuronal loss.These types of homeostatic changes could potentially explain the well-maintained visual function observed in patients with inherited retinal degenerative diseases who display prominent anatomic retinal pathology.This review will focus on our current understanding of retinal neuronal and Müller glial adaptation for the potential preservation of retinal activity during photoreceptor degeneration.Targeting retinal self-compensatory responses could help generate universal strategies to delay sensory disease progression.

Automated Classification of Inherited Retinal Diseases in Optical Coherence Tomography Images Using Few-shot Learning

Objective To develop a few-shot learning(FSL) approach for classifying optical coherence tomography(OCT) images in patients with inherited retinal disorders(IRDs).Methods In this study, an FSL model based on a student–teacher learning framework was designed to classify images. 2,317 images from 189 participants were included. Of these, 1,126 images revealed IRDs, 533 were normal samples, and 658 were control samples.Results The FSL model achieved a total accuracy of 0.974–0.983, total sensitivity of 0.934–0.957, total specificity of 0.984–0.990, and total F1 score of 0.935–0.957, which were superior to the total accuracy of the baseline model of 0.943–0.954, total sensitivity of 0.866–0.886, total specificity of 0.962–0.971,and total F1 score of 0.859–0.885. The performance of most subclassifications also exhibited advantages. Moreover, the FSL model had a higher area under curves(AUC) of the receiver operating characteristic(ROC) curves in most subclassifications.Conclusion This study demonstrates the effective use of the FSL model for the classification of OCT images from patients with IRDs, normal, and control participants with a smaller volume of data. The general principle and similar network architectures can also be applied to other retinal diseases with a low prevalence.

Organoid-derived human retinal progenitor cells promote early dedifferentiation of Müller glia in Royal College of Surgeons rats

AIM:To explore whether the subretinal transplantation of retinal progenitor cells from human embryonic stem cell-derived retinal organoid(h ERO-RPCs)could promote Müller glia dedifferentiation and transdifferentiation,thus improving visual function and delaying retinal degenerative progression.METHODS:h ERO-RPCs were subretinally transplanted into Royal College of Surgeons(RCS)rats.Electroretinography(ERG)recording was performed at 4 and 8wk postoperation to assess retinal function.Using immunofluorescence,the changes in outer nuclear layer(ONL)thickness and retinal Müller glia were explored at 2,4,and 8wk postoperation.To verify the effect of h ERO-RPCs on Müller glia in vitro,we cocultured h ERO-RPCs with Müller glia with a Transwell system.After coculture,Ki67 staining and quantitative polymerase chain reaction(q PCR)were performed to measure the proliferation and m RNA levels of Müller glia respectively.Cell migration experiment was used to detect the effect of h ERO-RPCs on Müller glial migration.Comparisons between two groups were performed by the unpaired Student’s t-test,and comparisons among multiple groups were made with one-way ANOVA followed by Tukey’s multiple comparison test.RESULTS:The visual function and ONL thickness of RCS rats were significantly improved by transplantation of h ERO-RPCs at 4 and 8wk postoperation.In addition to inhibiting gliosis at 4 and 8wk postoperation,h ERO-RPCs significantly increased the expression of dedifferentiation-associated transcriptional factor in Müller glia and promoted the migration at 2,4 and 8wk postoperation,but not the transdifferentiation of these cells in RCS rats.In vitro,using the Transwell system,we found that h ERO-RPCs promoted the proliferation and migration of primary rat Müller glia and induced their dedifferentiation at the m RNA level.CONCLUSION:These results show that h ERO-RPCs might promote early dedifferentiation of Müller glia,which may provide novel insights into the mechanisms of stem cell therapy and Müller glial reprogramming,contributing to the development of novel therapies for retinal degeneration disorders.

Risk factors and prognosis of pediatric rhegmatogenous retinal detachment in Egypt:a university hospital based study

AIM:To study and compare the predisposing factors and clinical features of pediatric,adult,and elderly rhegmatogenous retinal detachment(RRD).METHODS:This is an observational analytic crosssectional study in which patients with RRD admitted for surgery during 6mo period were divided into 3 age groups:pediatric(<18y),adult(18-60y),and elderly(>60y).Patients’demographic data,clinical features,RRD predisposing factors/features including myopia(axial length≥26.5 mm),aphakia/pseudophakia,blunt trauma,peripheral retinal degenerations,history of RRD in the fellow eye,and surgical interventions/findings were recorded and analyzed.RESULTS:Totally 142 patients(142 eyes)were studied:26(18.31%)pediatrics,86(60.56%)adults,and 30(21.13%)elderly.Elderly patients had a significantly higher intraocular pressures and cataracts compared to the other 2 groups(P=0.04).The RRD extent was larger in pediatric group(mostly 4 quadrants)compared to adults and elderly(mostly 2 quadrants),but it was not statistically insignificant(P=0.242).There were not statistically significantly differences in proliferative vitreoretinopathy(PVR)rate,posterior vitreous detachment(PVD)rate,number,site,shape,and size of breaks in three groups.All three groups had macular detachment in all eyes.Myopia and peripheral retinal degenerations were found to be more significant in adults(P=0.049,P=0.035,respectively),while blunt trauma was higher but insignificant in pediatric eyes(P=0.052).Pars plana vitrectomy(PPV)with silicone oil as a tamponade was the most used surgery in all groups.CONCLUSION:There are no significant difference in PVR rate in pediatric eyes but a significant higher rate of total RRD.Blunt trauma is more frequent in pediatrics eyes while myopia and/or peripheral retinal degenerations are more frequent in older ages.The rate of PPV as a choice for surgery is similar among all age groups.

Surgical treatment for neovascularized retinal pigment epithelial detachment in age -related macular degeneration

Dear Sir, I am Dr. Hui Li, from the Department of Ophthalmology of Shanghai Tenth People’s Hospital Affiliated to Tongji University in Shanghai, China. I write to report a case of neovascularized pigment epithelial detachment (PED) successfully treated with vitrectomy. PED associated occult choroidal neovascular membrane, so called vascularized PED [1] , is a special subtype of neovascular age-related macular degeneration with poor

Lycium barbarum glycopeptide(wolfberry extract)slows N-methyl-N-nitrosourea-induced degradation of photoreceptors

Photoreceptor cell degeneration leads to blindness, for which there is currently no effective treatment. Our previous studies have shown that Lycium barbarum(L. barbarum) polysaccharide(LBP) protects degenerated photoreceptors in rd1, a transgenic mouse model of retinitis pigmentosa. L. barbarum glycopeptide(Lb GP) is an immunoreactive glycoprotein extracted from LBP. In this study, we investigated the potential protective effect of Lb GP on a chemically induced photoreceptor-degenerative mouse model. Wild-type mice received the following: oral administration of Lb GP as a protective pre-treatment on days 1–7;intraperitoneal administration of 40 mg/kg N-methylN-nitrosourea to induce photoreceptor injury on day 7;and continuation of orally administered Lb GP on days 8–14. Treatment with Lb GP increased photoreceptor survival and improved the structure of photoreceptors, retinal photoresponse, and visual behaviors of mice with photoreceptor degeneration. Lb GP was also found to partially inhibit the activation of microglia in N-methyl-N-nitrosourea-injured retinas and significantly decreased the expression of two pro-inflammatory cytokines. In conclusion, Lb GP effectively slowed the rate of photoreceptor degeneration in N-methyl-N-nitrosourea-injured mice, possibly through an anti-inflammatory mechanism, and has potential as a candidate drug for the clinical treatment of photoreceptor degeneration.

Single-cell RNA sequencing analysis of the retina under acute high intraocular pressure

High intraocular pressure causes retinal ganglion cell injury in primary and secondary glaucoma diseases,yet the molecular landscape characteristics of retinal cells under high intraocular pressure remain unknown.Rat models of acute hypertension ocular pressure were established by injection of cross-linked hyaluronic acid hydrogel(Healaflow■).Single-cell RNA sequencing was then used to describe the cellular composition and molecular profile of the retina following high intraocular pressure.Our results identified a total of 12 cell types,namely retinal pigment epithelial cells,rod-photoreceptor cells,bipolar cells,Müller cells,microglia,cone-photoreceptor cells,retinal ganglion cells,endothelial cells,retinal progenitor cells,oligodendrocytes,pericytes,and fibroblasts.The single-cell RNA sequencing analysis of the retina under acute high intraocular pressure revealed obvious changes in the proportions of various retinal cells,with ganglion cells decreased by 23%.Hematoxylin and eosin staining and TUNEL staining confirmed the damage to retinal ganglion cells under high intraocular pressure.We extracted data from retinal ganglion cells and analyzed the retinal ganglion cell cluster with the most distinct expression.We found upregulation of the B3gat2 gene,which is associated with neuronal migration and adhesion,and downregulation of the Tsc22d gene,which participates in inhibition of inflammation.This study is the first to reveal molecular changes and intercellular interactions in the retina under high intraocular pressure.These data contribute to understanding of the molecular mechanism of retinal injury induced by high intraocular pressure and will benefit the development of novel therapies.

Photobiomodulation for the treatment of retinal diseases: a review

Photobiomodulation（PBM）,also known as low level laser therapy,has recently risen to the attention of the ophthalmology community as a promising new approach to treat a variety of retinal conditions including agerelated macular degeneration,retinopathy of prematurity,diabetic retinopathy,Leber’s hereditary optic neuropathy,amblyopia,methanol-induced retinal damage,and possibly others.This review evaluates the existing research pertaining to PBM applications in the retina,with a focus on the mechanisms of action and clinical outcomes.All available literature until April 2015 was reviewed using Pub Med and the following keywords：＂photobiomodulation AND retina＂,＂low level light therapy AND retina＂,＂low level laser therapy AND retina＂,and＂FR/NIR therapy AND retina＂.In addition,the relevant references listed within the papers identified through Pub Med were incorporated.The literature supports the conclusion that the low-cost and noninvasive nature of PBM,coupled with the first promising clinical reports and the numerous preclinical-studies in animal models,make PBM well-poised to become an important player in the treatment of a wide range of retinal disorders.Nevertheless,large-scale clinical trials will be necessary to establish the PBM therapeutic ranges for the various retinal diseases,as well as to gain a deeper understanding of its mechanisms of action.

Luteolin delays photoreceptor degeneration in a mouse model of retinitis pigmentosa

Luteolin is neuroprotective for retinal ganglion cells and retinal pigment epithelial cells after oxidative injury,whereby it can inhibit microglial neurotoxicity.Therefore,luteolin holds the potential to be useful for treatment of retinal diseases.The purpose of this study was to investigate whether luteolin exhibits neuroprotective effects on rod cells in rd10 mice,a slow photoreceptor-degenerative model of retinitis pigmentosa.Luteolin(100 mg/kg)intraperitoneally injected daily from postnatal day 14(P14)to P25 significantly enhanced the visual performance and retinal light responses of rd10 mice at P25.Moreover,it increased the survival of photoreceptors and improved retinal structure.Mechanistically,luteolin treatment attenuated increases in reactive oxygen species,photoreceptor apoptosis,and reactive gliosis;increased mRNA levels of anti-inflammatory cytokines while lowering that of pro-inflammatory and chemoattractant cytokines;and lowered the ratio of phospho-JNK/JNK.Application of the JNK inhibitor SP600125 exerted a similar protective effect to luteolin,suggesting that luteolin delays photoreceptor degeneration and functional deterioration in rd10 mice through regulation of retinal oxidation and inflammation by inhibiting the JNK pathway.Therefore,luteolin may be useful as a supplementary treatment for retinitis pigmentosa.This study was approved by the Qualified Ethics Committee of Jinan University,China(approval No.IACUC-20181217-02)on December 17,2018.

Lutein delays photoreceptor degeneration in a mouse model of retinitis pigmentosa

Retinitis pigmentosa is a retinal disease characterized by photoreceptor degeneration.There is currently no effective treatment for retinitis pigmentosa.Although a mixture of lutein and other antioxidant agents has shown promising effects in protecting the retina from degeneration,the role of lutein alone remains unclear.In this study,we administered intragastric lutein to Pde6brd10 model mice,which display degeneration of retinal photoreceptors,on postnatal days 17(P17)to P25,when rod apoptosis reaches peak.Lutein at the optimal protective dose of 200 mg/kg promoted the survival of photoreceptors compared with vehicle control.Lutein increased rhodopsin expression in rod cells and opsin expression in cone cells,in line with an increased survival rate of photoreceptors.Functionally,lutein improved visual behavior,visual acuity,and retinal electroretinogram responses in Pde6brd10 mice.Mechanistically,lutein reduced the expression of glial fibrillary acidic protein in Müller glial cells.The results of this study confirm the ability of lutein to postpone photoreceptor degeneration by reducing reactive gliosis of Müller cells in the retina and exerting anti-inflammatory effects.This study was approved by the Laboratory Animal Ethics Committee of Jinan University(approval No.LACUC-20181217-02)on December 17,2018.

A hypothesis for treating inflammation and oxidative stress with hydrogen sulfide during age-related macular degeneration

Age-related macular degeneration（AMD） is a leading cause of blindness and is becoming a global crisis since affected people will increase to 288 million by 2040.Genetics,age,diabetes,gender,obesity,hypertension,race,hyperopia,iris-color,smoking,sun-light and pyroptosis have varying roles in AMD,but oxidative stress-induced inflammation remains a significant driver of pathobiology.Eye is a unique organ as it contains a remarkable oxygengradient that generates reactive oxygen species（ROS） which upregulates inflammatory pathways.ROS becomes a source of functional and morphological impairments in retinal pigment epithelium（RPE）,endothelial cells and retinal ganglion cells.Reports demonstrated that hydrogen sulfide（H2S） acts as a signaling molecule and that it may treat ailments.Therefore,we propose a novel hypothesis that H2S may restore homeostasis in the eyes thereby reducing damage caused by oxidative injury and inflammation.Since H_2S has been shown to be a powerful antioxidant because of its free-radicals＇ inhibition properties in addition to its beneficial effects in age-relatedconditions,therefore,patients may benefit from H2S salubrious effects not only by minimizing their oxidant and inflammatory injuries to retina but also by lowering retinal glutamate excitotoxicity.