p38 MAPK inhibitor SB202190 suppresses ferroptosis in the glutamate-induced retinal excitotoxicity glaucoma model

Glutamate excitotoxicity has been shown to play an important role in glaucoma, and glutamate can induce ferroptosis. The p38 mitogenactivated protein kinase(MAPK) pathway inhibitor SB202190 has a potential ability to suppress ferroptosis, and its downstream targets, such as p53, have been shown to be associated with ferroptosis. However, whether ferroptosis also occurs in retinal ganglion cells in response to glutamate excitotoxicity and whether inhibition of ferroptosis reduces the loss of retinal ganglion cells induced by glutamate excitotoxicity remain unclear. This study investigated ferroptosis in a glutamate-induced glaucoma rat model and explored the effects and molecular mechanisms of SB202190 on retinal ganglion cells. A glutamate-induced excitotoxicity model in R28 cells and an N-methyl-D-aspartate-induced glaucoma model in rats were used. In vitro experiments showed that glutamate induced the accumulation of iron and lipid peroxide and morphological changes of mitochondria in R28 cells, and SB202190 inhibited these changes. Glutamate induced the levels of p-p38 MAPK/p38 MAPK and SAT1 and decreased the expression levels of ferritin light chain, SLC7A11, and GPX4. SB202190 inhibited the expression of iron death-related proteins induced by glutamate. In vivo experiments showed that SB202190 attenuated N-methyl-D-aspartate-induced damage to rat retinal ganglion cells and improved visual function. These results suggest that SB202190 can inhibit ferroptosis and protect retinal ganglion cells by regulating ferritin light chain, SAT1, and SLC7A11/Gpx4 pathways and may represent a potential retina protectant.

Recent advances in the application of MXenes for neural tissue engineering and regeneration

Transition metal carbides and nitrides(MXenes)are crystal nanomaterials with a number of surface functional groups such as fluorine,hydroxyl,and oxygen,which can be used as carriers for proteins and drugs.MXenes have excellent biocompatibility,electrical conductivity,surface hydrophilicity,mechanical properties and easy surface modification.However,at present,the stability of most MXenes needs to be improved,and more synthesis methods need to be explored.MXenes are good substrates for nerve cell regeneration and nerve reconstruction,which have broad application prospects in the repair of nervous system injury.Regarding the application of MXenes in neuroscience,mainly at the cellular level,the long-term in vivo biosafety and effects also need to be further explored.This review focuses on the progress of using MXenes in nerve regeneration over the last few years;discussing preparation of MXenes and their biocompatibility with different cells as well as the regulation by MXenes of nerve cell regeneration in two-dimensional and three-dimensional environments in vitro.MXenes have great potential in regulating the proliferation,differentiation,and maturation of nerve cells and in promoting regeneration and recovery after nerve injury.In addition,this review also presents the main challenges during optimization processes,such as the preparation of stable MXenes and long-term in vivo biosafety,and further discusses future directions in neural tissue engineering.

Cell replacement with stem cell-derived retinal ganglion cells from different protocols

Glaucoma,characterized by a degenerative loss of retinal ganglion cells,is the second leading cause of blindness worldwide.There is currently no cure for vision loss in glaucoma because retinal ganglion cells do not regenerate and are not replaced after injury.Human stem cell-derived retinal ganglion cell transplant is a potential therapeutic strategy for retinal ganglion cell degenerative diseases.In this review,we first discuss a 2D protocol for retinal ganglion cell differentiation from human stem cell culture,including a rapid protocol that can generate retinal ganglion cells in less than two weeks and focus on their transplantation outcomes.Next,we discuss using 3D retinal organoids for retinal ganglion cell transplantation,comparing cell suspensions and clusters.This review provides insight into current knowledge on human stem cell-derived retinal ganglion cell differentiation and transplantation,with an impact on the field of regenerative medicine and especially retinal ganglion cell degenerative diseases such as glaucoma and other optic neuropathies.

Anti-vascular endothelial growth factor drugs combined with laser photocoagulation maintain retinal ganglion cell integrity in patients with diabetic macular edema: study protocol for a prospective, non-randomized, controlled clinical trial

The integrity of retinal ganglion cells is tightly associated with diabetic macular degeneration that leads to damage and death of retinal ganglion cells,affecting vision.The major clinical treatments for diabetic macular edema are anti-vascular endothelial growth factor drugs and laser photocoagulation.However,although the macular thickness can be normalized with each of these two therapies used alone,the vision does not improve in many patients.This might result from the incomplete recovery of retinal ganglion cell injury.Therefore,a prospective,non-randomized,controlled clinical trial was designed to investigate the effect of anti-vascular endothelial growth factor drugs combined with laser photocoagulation on the integrity of retinal ganglion cells in patients with diabetic macular edema and its relationship with vision recovery.In this trial,150 patients with diabetic macular edema will be equally divided into three groups according to therapeutic methods,followed by treatment with anti-vascular endothelial growth factor drugs,laser photocoagulation therapy,and their combination.All patients will be followed up for 12 months.The primary outcome measure is retinal ganglion cell-inner plexiform layer thickness at 12 months after treatment.The secondary outcome measures include retinal ganglion cell-inner plexiform layer thickness before and 1,3,6,and 9 months after treatment,retinal nerve fiber layer thickness,best-corrected visual acuity,macular area thickness,and choroidal thickness before and 1,3,6,9,and 12 months after treatment.Safety measure is the incidence of adverse events at 1,3,6,9,and 12 months after treatment.The study protocol hopes to validate the better efficacy and safety of the combined treatment in patients with diabetic macula compared with the other two monotherapies alone during the 12-month follow-up period.The trial is designed to focus on clarifying the time-effect relationship between imaging measures related to the integrity of retinal ganglion cells and best-corrected visual acuity.The trial protocol was approved by the Medical Ethics Committee of the Affiliated Hospital of Beihua University with approval No.(2023)(26)on April 25,2023,and was registered with the Chinese Clinical Trial Registry(registration number:ChiCTR2300072478,June 14,2023,protocol version:2.0).

Casein kinase-2 inhibition promotes retinal ganglion cell survival after acute intraocular pressure elevation

Intraocular pressure elevation can induce retinal ganglion cell death and is a clinically reversible risk factor for glaucoma,the leading cause of irreversible blindness.We previously demonstrated that casein kinase-2 inhibition can promote retinal ganglion cell survival and axonal regeneration in rats after optic nerve injury.To investigate the underlying mechanism,in the current study we increased the intraocular pressure of adult rats to 75 mmHg for 2 hours and then administered a casein kinase-2 inhibitor(4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole)by intravitreal injection.We found that intravitreal injection of 4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole promoted retinal ganglion cell survival and reduced the number of infiltrating macrophages.Transcriptomic analysis showed that the mitogen activated protein kinase signaling pathway was involved in the response to intraocular pressure elevation but was not modulated by the casein kinase-2 inhibitors.Furthermore,casein kinase-2 inhibition downregulated the expression of genes(Cck,Htrsa,Nef1,Htrlb,Prph,Chat,Slc18a3,Slc5a7,Scn1b,Crybb2,Tsga10ip,and Vstm21)involved in intraocular pressure elevation.Our data indicate that inhibition of casein kinase-2 can enhance retinal ganglion cell survival in rats after acute intraocular pressure elevation via macrophage inactivation.

Prediction of cell-cell communication patierns of dorsal root ganglion cells:single-cell RNA sequencing data analysis

Dorsal root ganglion neurons transmit peripheral somatic information to the central nervous system,and dorsal root ganglion neuron excitability affects pain perception.Dorsal root ganglion stimulation is a new approach for managing pain sensation.Knowledge of the cell-cell communication among dorsal root ganglion cells may help in the development of new pain and itch management strategies.Here,we used the single-cell RNA-sequencing(scRNA-seq)database to investigate intercellular communication networks among dorsal root ganglion cells.We collected scRNA-seq data from six samples from three studies,yielding data on a total of 17,766 cells.Based on genetic profiles,we identified satellite glial cells,Schwann cells,neurons,vascular endothelial cells,immune cells,fibroblasts,and vascular smooth muscle cells.Further analysis revealed that eight types of dorsal root ganglion neurons mediated proprioceptive,itch,touch,mechanical,heat,and cold sensations.Moreover,we predicted several distinct forms of intercellular communication among dorsal root ganglion cells,including cell-cell contact,secreted signals,extracellular matrix,and neurotransmitter-mediated signals.The data mining predicted that Mrgpra3-positive neurons robustly express the genes encoding the adenosine Adora2b(A2B)receptor and glial cell line-derived neurotrophic factor family receptor alpha 1(GFRα-1).Our immunohistochemistry results confirmed the coexpression of the A2B receptor and GFRα-1.Intrathecal injection of the A2B receptor antagonist PSB-603 effectively prevented histamine-induced scratching behaviour in a dose-dependent manner.Our results demonstrate the involvement of the A2B receptor in the modulation of itch sensation.Furthermore,our findings provide insight into dorsal root ganglion cell-cell communication patterns and mechanisms.Our results should contribute to the development of new strategies for the regulation of dorsal root ganglion excitability.

Neuroprotective effects of resveratrol on retinal ganglion cells in glaucoma in rodents:A narrative review

Glaucoma,an irreversible optic neuropathy,primarily affects retinal ganglion cells(RGC)and causes vision loss and blindness.The damage to RGCs in glaucoma occurs by various mechanisms,including elevated intraocular pressure,oxidative stress,inflammation,and other neurodegenerative processes.As the disease progresses,the loss of RGCs leads to vision loss.Therefore,protecting RGCs from damage and promoting their survival are important goals in managing glaucoma.In this regard,resveratrol(RES),a polyphenolic phytoalexin,exerts antioxidant effects and slows down the evolution and progression of glaucoma.The present review shows that RES plays a protective role in RGCs in cases of ischemic injury and hypoxia as well as in ErbB2 protein expression in the retina.Additionally,RES plays protective roles in RGCs by promoting cell growth,reducing apoptosis,and decreasing oxidative stress in H_(2)O_(2)-exposed RGCs.RES was also found to inhibit oxidative stress damage in RGCs and suppress the activation of mitogen-activated protein kinase signaling pathways.RES could alleviate retinal function impairment by suppressing the hypoxia-i nducible factor-1 alpha/vascular endothelial growth factor and p38/p53 axes while stimulating the PI3K/Akt pathway.Therefore,RES might exert potential therapeutic effects for managing glaucoma by protecting RGCs from damage and promoting their survival.

The concept of gene therapy for glaucoma:the dream that has not come true yet

Gene therapies,despite of being a relatively new therapeutic approach,have a potential to become an important alternative to current treatment strategies in glaucoma.Since glaucoma is not considered a single gene disease,the identified goals of gene therapy would be rather to provide neuroprotection of retinal ganglion cells,especially,in intraocular-pressure-independent manner.The most commonly reported type of vector for gene delivery in glaucoma studies is adeno-associated virus serotype 2 that has a high tro pism to retinal ganglion cells,res ulting in long-term expression and low immunogenic profile.The gene thera py studies recruit inducible and genetic animal models of optic neuropathy,like DBA/2J mice model of high-tension glaucoma and the optic nerve crush-model.Reported gene therapy-based neuroprotection of retinal ganglion cells is targeting specific genes translating to growth factors(i.e.,brain derived neurotrophic factor,and its receptor TrkB),regulation of apoptosis and neurodegeneration(i.e.,Bcl-xl,Xiap,FAS system,nicotinamide mononucleotide adenylyl transferase 2,Digit3 and Sarm1),immunomodulation(i.e.,Crry,C3 complement),modulation of neuroinflammation(i.e.,e rythropoietin),reduction of excitotoxicity(i.e.,Com KIlα)and transcription regulation(i.e.,Max,Nrf2).On the other hand,some of gene therapy studies focus on lowering intra ocular pressure,by impacting genes involved in both,decreasing aqueous humor production(i.e.,aquaporin 1),and increasing outflow facility(i.e.,COX2,prostaglandin F2a receptor,RhoA/RhoA kinase signaling pathway,MMP1,Myocilin).The goal of this review is to summarize the current stateof-art and the direction of development of gene therapy strategies for glaucomatous neuropathy.

Mesenchymal stem cells for repairing glaucomatous optic nerve

Glaucoma is a common and complex neurodegenerative disease characterized by progressive loss of retinal ganglion cells(RGCs)and axons.Currently,there is no effective method to address the cause of RGCs degeneration.However,studies on neuroprotective strategies for optic neuropathy have increased in recent years.Cell replacement and neuroprotection are major strategies for treating glaucoma and optic neuropathy.Regenerative medicine research into the repair of optic nerve damage using stem cells has Received considerable attention.Stem cells possess the potential for multidirectional differentiation abilities and are capable of producing RGCfriendly microenvironments through paracrine effects.This article reviews a thorough researches of recent advances and approaches in stem cell repair of optic nerve injury,raising the controversies and unresolved issues surrounding the future of stem cells.

Small extracellular vesicles derived from human induced pluripotent stem cell-differentiated neural progenitor cells mitigate retinal ganglion cell degeneration in a mouse model of optic nerve injury

Several studies have found that transplantation of neural progenitor cells(NPCs)promotes the survival of injured neurons.However,a poor integration rate and high risk of tumorigenicity after cell transplantation limits their clinical application.Small extracellular vesicles(sEVs)contain bioactive molecules for neuronal protection and regeneration.Previous studies have shown that stem/progenitor cell-derived sEVs can promote neuronal survival and recovery of neurological function in neurodegenerative eye diseases and other eye diseases.In this study,we intravitreally transplanted sEVs derived from human induced pluripotent stem cells(hiPSCs)and hiPSCs-differentiated NPCs(hiPSC-NPC)in a mouse model of optic nerve crush.Our results show that these intravitreally injected sEVs were ingested by retinal cells,especially those localized in the ganglion cell layer.Treatment with hiPSC-NPC-derived sEVs mitigated optic nerve crush-induced retinal ganglion cell degeneration,and regulated the retinal microenvironment by inhibiting excessive activation of microglia.Component analysis further revealed that hiPSC-NPC derived sEVs transported neuroprotective and anti-inflammatory miRNA cargos to target cells,which had protective effects on RGCs after optic nerve injury.These findings suggest that sEVs derived from hiPSC-NPC are a promising cell-free therapeutic strategy for optic neuropathy.

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.

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.

Protein arginine methyltransferase-6 regulates heterogeneous nuclear ribonucleoprotein-F expression and is a potential target for the treatment of neuropathic pain

Protein arginine methyltransferase-6 participates in a range of biological functions,particularly RNA processing,transcription,chromatin remodeling,and endosomal trafficking.However,it remains unclear whether protein arginine methyl transferase-6 modifies neuropathic pain and,if so,what the mechanisms of this effect.In this study,protein arginine methyltransferase-6 expression levels and its effect on neuropathic pain were investigated in the spared nerve injury model,chronic constriction injury model and bone cancer pain model,using immunohistochemistry,western blotting,immunoprecipitation,and label-free proteomic analysis.The results showed that protein arginine methyltransferase-6 mostly co-localized withβ-tubulinⅢin the dorsal root ganglion,and that its expression decreased following spared nerve injury,chronic constriction injury and bone cancer pain.In addition,PRMT6 knockout(Prmt6~(-/-))mice exhibited pain hypersensitivity.Furthermore,the development of spared nerve injury-induced hypersensitivity to mechanical pain was attenuated by blocking the decrease in protein arginine methyltransferase-6 expression.Moreover,when protein arginine methyltransferase-6 expression was downregulated in the dorsal root ganglion in mice without spared nerve injury,increased levels of phosphorylated extracellular signal-regulated kinases were observed in the ipsilateral dorsal horn,and the response to mechanical stimuli was enhanced.Mechanistically,protein arginine methyltransferase-6 appeared to contribute to spared nerve injury-induced neuropathic pain by regulating the expression of heterogeneous nuclear ribonucleoprotein-F.Additionally,protein arginine methyltransfe rase-6-mediated modulation of hete rogeneous nuclear ribonucleoprotein-F expression required amino atids 319 to 388,but not classical H3R2 methylation.These findings indicated that protein arginine methyltransferase-6 is a potential therapeutic target fo r the treatment of peripheral neuro pathic pain.

Effect of Sonic hedgehog gene-modified bone marrow mesenchymal stem cells on graft-induced retinal gliosis and retinal ganglion cells survival in diabetic mice

AIM:To investigate the effects of Sonic hedgehog(Shh)gene-modified bone marrow mesenchymal stem cells(MSCs)on graft-induced retinal gliosis and retinal ganglion cells(RGCs)survival in diabetic mice.METHODS:Bone marrow-derived MSCs were genetically modified with the Shh gene to generate a stably transfected cell line of Shh-modified MSCs(MSC-Shh).Intravitreal injections of MSC-Shh and green fluorescent protein-modified MSCs(MSC-Gfp;control)were administered in diabetic mice.After 4wk,the effects of MSC-Shh on retinal gliosis were evaluated using fundus photography,and markers of gliosis were examined by immunofluorescence and Western blotting.The neurotrophic factors expression and RGCs survival in the host retina were evaluated using Western blotting and immunofluorescence.The mechanisms underlying the effects of MSC-Shh was investigated.RESULTS:A significant reduction of proliferative vitreoretinopathy(PVR)was observed after intravitreal injection of MSC-Shh compared to MSC-Gfp.Significant downregulation of glial fibrillary acidic protein(GFAP)was demonstrated in the host retina after MSC-Shh administration compared to MSC-Gfp.The extracellular signal-regulated kinase 1/2(ERK1/2),protein kinase B(AKT)and phosphatidylin-ositol-3-kinase(PI3K)pathways were significantly downregulated after MSC-Shh administration compared to MSC-Gfp.Brain-derived neurotrophic factor(BDNF)and ciliary neurotrophic factor(CNTF)levels were significantly increased in the host retina,and RGCs loss was significantly prevented after MSC-Shh administration.CONCLUSION:MSC-Shh administration reduces graft-induced reactive gliosis following intravitreal injection in diabetic mice.The ERK1/2,AKT and PI3K pathways are involved in this process.MSC-Shh also increases the levels of neurotrophic factors in the host retina and promoted RGCs survival in diabetic mice.

MP-3 microperimeter in early primary open angle glaucoma with a new pattern

AIM:To investigate macular microperimetry in patients with early primary open angle glaucoma(POAG)using a new custom-made pattern,and analyze the characteristics of macular sensitivity.METHODS:This case-control study included 38 patients with POAG,who were divided into pre-perimetric glaucoma(18 eyes of 18 patients),early-stage(20 eyes of 20 patients),and control(20 eyes of 20 patients)groups.All subjects underwent standard 24-2 humphrey visual field test.An MP-3 microperimeter with a new custom-made pattern(28 testing points distributed in four quadrants,covering the central 10°of the retina)was used to evaluate macular sensitivity.Ganglion cell complex(GCC)thicknesses were examined using an RS-3000 Advance OCT system.The features of structure and function were analysed per quadrant.RESULTS:The pre-perimetric glaucoma group had significantly lower inferior hemifield macular sensitivity compared to controls(P<0.05).The early-stage POAG group had significantly lower average,inferior hemifield,inferonasal,and inferotemporal mean sensitivities compared to the pre-perimetric glaucoma group(P<0.05),and lower macular sensitivity in all sectors compared to controls(P<0.05).Regarding GCC thickness,all sectors in the early-stage POAG group became thinner compared to those in controls(P<0.05);whereas all sectors in the early-stage POAG group,except the superonasal quadrant,became thinner compared to those in the pre-perimetric glaucoma group(P<0.05).Macular sensitivity and GCC thickness were significantly associated in each sector.The inferotemporal quadrant had the highest correlation coefficients(0.840).The structure-function relationship for the inferonasal and inferotemporal sectors was stronger compared to the corresponding superior sectors.CONCLUSION:Microperimetry reveals variations in macular sensitivity in patients with early glaucoma earlier than conventional perimetry,particularly in pre-perimetric glaucoma cases in which it might be undetectable by conventional methods.The new custom-made pattern may improve the accuracy of microperimetry by enhancing point arrangement and reducing fatigue effects.Macular sensitivity measured by MP-3 with this pattern shows statistically significant structural and functional associations with the thicknesses of the GCC.

In vivo imaging of the neuronal response to spinal cord injury:a narrative review

Deciphering the neuronal response to injury in the spinal cord is essential for exploring treatment strategies for spinal cord injury(SCI).However,this subject has been neglected in part because appropriate tools are lacking.Emerging in vivo imaging and labeling methods offer great potential for observing dynamic neural processes in the central nervous system in conditions of health and disease.This review first discusses in vivo imaging of the mouse spinal cord with a focus on the latest imaging techniques,and then analyzes the dynamic biological response of spinal cord sensory and motor neurons to SCI.We then summarize and compare the techniques behind these studies and clarify the advantages of in vivo imaging compared with traditional neuroscience examinations.Finally,we identify the challenges and possible solutions for spinal cord neuron imaging.

Differential response of injured and healthy retinas to syngeneic and allogeneic transplantation of a clonal cell line of immortalized olfactory ensheathing glia:a double-edged sword

Olfactory ensheathing glia promote axonal regeneration in the mammalian central nervous system,including retinal ganglion cell axonal growth through the injured optic nerve.Still,it is unknown whether olfactory ensheathing glia also have neuroprotective properties.Olfactory ensheathing glia express brain-derived neurotrophic factor,one of the best neuroprotectants for axotomized retinal ganglion cells.Therefore,we aimed to investigate the neuroprotective capacity of olfactory ensheating glia after optic nerve crush.Olfactory ensheathing glia cells from an established rat immortalized clonal cell line,TEG3,were intravitreally injected in intact and axotomized retinas in syngeneic and allogeneic mode with or without microglial inhibition or immunosuppressive treatments.Anatomical and gene expression analyses were performed.Olfactory bulb-derived primary olfactory ensheathing glia and TEG3 express major histocompatibility complex classⅡmolecules.Allogeneically and syngenically transplanted TEG3 cells survived in the vitreous for up to 21 days,forming an epimembrane.In axotomized retinas,only the allogeneic TEG3 transplant rescued retinal ganglion cells at 7 days but not at 21 days.In these retinas,microglial anatomical activation was higher than after optic nerve crush alone.In intact retinas,both transplants activated microglial cells and caused retinal ganglion cell death at 21 days,a loss that was higher after allotransplantation,triggered by pyroptosis and partially rescued by microglial inhibition or immunosuppression.However,neuroprotection of axotomized retinal ganglion cells did not improve with these treatments.The different neuroprotective properties,different toxic effects,and different responses to microglial inhibitory treatments of olfactory ensheathing glia in the retina depending on the type of transplant highlight the importance of thorough preclinical studies to explore these variables.

Etomidate protects retinal ganglion cells from hydrogen peroxide-induced injury via Nrf2/HO-1 pathway

AIM:To determine whether etomidate(ET)has a protective effect on retinal ganglion cells(RGCs)injured with hydrogen peroxide(H_(2)O_(2))and to explore the potential mechanism underlying the antioxidative stress effect of ET.METHODS:Cultured RGCs were identified by double immunofluorescent labeling of microtubule-associated protein 2 and Thy1.1.An injury model of H_(2)O_(2)-induced RGCs oxidative stress was established in vitro.Cells were pretreated with different concentrations of ET(1,5,and 10μmol/L)for 4h,followed by further exposure to H_(2)O_(2)at 1000μmol/L.Cell counting kit 8 and Annexin V/propidium iodide assays were applied to detect the viabilities and apoptosis rates of the RGCs at 12,24,and 48h after H_(2)O_(2)stimulation.The levels of nitric oxide,malondialdehyde,and glutathione in culture media were measured at these time points.Quantitative reverse transcription polymerase chain reaction(qRT-PCR)and Western blot were performed to observe the effects of ET on the messenger RNA and protein expression of inducible nitric oxide synthase(iNOS),nuclear factor erythroid 2-related factor 2(Nrf2),heme oxygenase 1(HO-1),glutathione peroxidase 1 and the level of conjugated acrolein in RGCs at 12,24,and 48h after H_(2)O_(2)stimulation and in the retina at 12h after optic nerve transection(ONT).RESULTS:The applications of 5 and 10μmol/L of ET significantly increased the viability of RGCs.Results from qRT-PCR indicated a decrease in the expression of iNOS and an increase in the expressions of Nrf2 and HO-1 in ETpretreated RGCs at 12,24 and 48h after H_(2)O_(2)stimulation,as well as in ET-treated retinas at 12h after ONT.Western blot analysis revealed a decrease in the expression of iNOS and levels of conjugated acrolein,along with an increase in the expressions of Nrf2 and HO-1 in ET-pretreated RGCs in vitro and ET-treated retinas in vivo.CONCLUSION:ET is a neuroprotective agent in primary cultured RGCs injured by H_(2)O_(2).The effect of ET is dosedependent with the greatest effect being at 10μmol/L.ET plays an antioxidant role by inhibiting iNOS,up-regulating Nrf2/HO-1,decreasing the production of acrolein,and increasing the scavenge of acrolein.

Indirubin alleviates retinal neurodegeneration through the regulation of PI3K/AKT signaling

Retinal neurodegenerative disease is a leading cause of blindness among the elderly in developed countries,including glaucoma,diabetic retinopathy,traumatic optic neuropathy and optic neuritis,etc.The current clinical treatment is not very effective.We investigated indirubin,one of the main bioactive components of the traditional Chinese medicine Danggui Longhui Pill,in the present study for its role in retinal neurodegeneration.Indirubin exhibited no detectable tissue toxicity in vivo or cytotoxicity in vitro.Moreover,indirubin improved visual function and ameliorated retinal neurodegeneration in mice after optic nerve crush injury in vivo.Furthermore,indirubin reduced the apoptosis of retinal ganglion cells induced by oxidative stress in vitro.In addition,indirubin significantly suppressed the increased production of intracellular reactive oxygen species and the decreased activity of superoxide dismutase induced by oxidative stress.Mechanically,indirubin played a neuroprotective role by regulating the PI3K/AKT/BAD/BCL-2 signaling.In conclusion,indirubin protected retinal ganglion cells from oxidative damage and alleviated retinal neurodegeneration induced by optic nerve crush injury.The present study provides a potential therapeutic medicine for retinal neurodegenerative diseases.

Values of macular ganglion cell-inner plexiform layer and 10-2 visual field measurements in detecting and evaluating glaucoma

AIM:To assess the performance of macular ganglion cell-inner plexiform layer thickness(mGCIPLT)and 10-2 visual field(VF)parameters in detecting early glaucoma and evaluating the severity of advanced glaucoma.METHODS:Totally 127 eyes from 89 participants(36 eyes of 19 healthy participants,45 eyes of 31 early glaucoma patients and 46 eyes of 39 advanced glaucoma patients)were included.The relationships between the optical coherence tomography(OCT)-derived parameters and VF sensitivity were determined.Patients with early glaucoma were divided into eyes with or without central 10°of the VF damages(CVFDs),and the diagnostic performances of OCT-derived parameters were assessed.RESULTS:In early glaucoma,the mGCIPLT was significantly correlated with 10-2 VF pattern standard deviation(PSD;with average mGCIPLT:β=-0.046,95%CI,-0.067 to-0.024,P<0.001).In advanced glaucoma,the mGCIPLT was related to the 24-2 VF mean deviation(MD;with average mGCIPLT:β=0.397,95%CI,0.199 to 0.595,P<0.001),10-2 VF MD(with average mGCIPLT:β=0.762,95%CI,0.485 to 1.038,P<0.001)and 24-2 VF PSD(with average mGCIPLT:β=0.244,95%CI,0.124 to 0.364,P<0.001).Except for the minimum and superotemporal mGCIPLT,the decrease of mGCIPLT in early glaucomatous eyes with CVFDs was more severe than that of early glaucomatous eyes without CVFDs.The area under the curve(AUC)of the average mGCIPLT(AUC=0.949,95%CI,0.868 to 0.982)was greater than that of the average circumpapillary retinal nerve fiber layer thickness(cpRNFLT;AUC=0.827,95%CI,0.674 to 0.918)and rim area(AUC=0.799,95%CI,0.610 to 0.907)in early glaucomatous eyes with CVFDs versus normal eyes.CONCLUSION:The 10-2 VF and mGCIPLT parameters are complementary to 24-2 VF,cpRNFLT and ONH parameters,especially in detecting early glaucoma with CVFDs and evaluating the severity of advanced glaucoma in group level.