Photoreceptor oxidative damage in sympathetic ophthalmia

Hyper-Reflective Outer Nuclear Layer (HONL) in Vogt-Koyanagi-Harada Disease and Sympathetic Ophthalmia

PURPOSE

To describe the optical coherence tomography (OCT) findings of hyper-reflective outer nuclear layer (HONL) in two cases of stromal choroiditis (Vogt-Koyanagi-Harada disease - VKH, and sympathetic ophthalmia - SO).

METHODS

Case report.

RESULTS

Clinical and imaging findings of two patients (37-year-old female with VKH and 34-year-old male with SO) have been described. Both patients showed typical features of the disease with subretinal fluid accumulation and choroidal thickening on OCT. However, OCT of both patients at the initial visit revealed HONL, which was unusual in these conditions. During follow-up, OCT scans revealed thinning and atrophy of the outer retinal layers, irregular thickening of the retinal pigment epithelium, and irregular autofluorescence pattern on autofluorescence imaging.

CONCLUSIONS

The presence of HONL may serve as a poor prognostic factor in VKH and SO, resulting in thinning and atrophy of the outer retinal layers.

Local Myeloid-Derived Suppressor Cells Impair Progression of Experimental Autoimmune Uveitis by Alleviating Oxidative Stress and Inflammation

Purpose

To evaluate the immune regulatory effect of human cord blood myeloid-derived suppressor cells (MDSCs) in experimental autoimmune uveitis (EAU) models.

Methods

MDSCs (1 × 106) or PBS were injected into established C57BL/6 EAU mice via the subconjunctival route on days 0 and 7. The severity of intraocular inflammation was evaluated for up to 3 weeks. Tissue injury and inflammation were analyzed using immunolabelled staining, real-time PCR, and ELISA. In addition, immune cells in draining lymph nodes (LNs) were quantified using flow cytometry.

Results

After 21 days, the clinical scores and histopathological grades of EAU were lower in the MDSCs group compared with the PBS group. Local administration of MDSCs suppressed the oxidative stress and the expression of TNF-α and IL-1β in the retinal tissues. In addition, it inhibited the activation of pathogenic T helper 1 (Th1) and Th17 cells in draining LNs. MDSCs increased the frequency of CD25+ Foxp3+ regulatory T cells and the mRNA expression of IL-10, as an immune modulator.

Conclusions

MDSCs suppressed inflammation and oxidative stress in the retina and inhibited pathogenic T cells in the LNs in EAU. Therefore, ocular administration of MDSCs has therapeutic potential for uveitis.

Acute and Chronic Manifestations of Sympathetic Ophthalmia on Multimodal Imaging

PURPOSE

To report the clinical and multimodal imaging features of sympathetic ophthalmia in the acute and chronic phases.

METHODS

Retrospective cohort study of consecutive patients with sympathetic ophthalmia seen at a tertiary referral center. Charts, imaging studies, and histopathological specimens were reviewed. The clinical features and multimodal imaging in the sympathizing eye were analyzed by sorting features into those seen in the acute and chronic phase.

RESULTS

Ten patients were included in the analysis and all of them had previous ocular trauma or complicated retinal detachment. In the acute phase, 70% had anterior uveitis, 70% had vitritis, and 100% had active posterior uveitis; posterior uveitis included multifocal choroiditis (80%), optic disc swelling (40%), multiple serous retinal detachments (20%), MEWDS-like findings (10%), and retinal vasculitis with chorioretinitis (10%). In the chronic phase, posterior manifestations included widespread patches of chorioretinal atrophy in the mid- and far-periphery (80%), peripapillary subretinal fibrosis (50%), and nummular perivascular atrophy (50%).

CONCLUSIONS

Sympathetic ophthalmia shows different posterior segment manifestations in the acute and chronic phase. Active sympathetic ophthalmia should be ruled out in eyes with a MEWDS-like presentation or rapidly progressing chorioretinitis, and history of trauma in the fellow eye. Peripapillary subretinal fibrosis and perivascular nummular atrophy may be useful features to suspect SO once acute inflammation has resolved.

Leopard retinopathy: An unusual presentation of sympathetic ophthalmia

We report an unusual case of sympathetic ophthalmia (SO) in an elderly gentleman following multiple eye surgeries. He presented with diffuse granulomatous panuveitis resembling leopard retinopathy in the left eye. There was a delay in the initiation of effective treatment of his intraocular inflammation, but he responded to corticosteroid and azathioprine. The pigmentary changes in his fundus were highly unusual, and he was investigated extensively to rule out other possible causes including a search for occult malignancy. The delay in initiation of effective treatment or suboptimal therapy in SO, can lead to variable clinical picture in elderly patients. A proper screening to exclude any malignancy along with aggressive immunosuppressive therapy can achieve optimum results.

Sympathetic Ophthalmia: Where Do We Currently Stand on Treatment Strategies?

Sympathetic ophthalmia is a rare bilateral diffuse granulomatous panuveitis that usually results from surgical or penetrating trauma to one eye. The symptoms range from impaired near vision to pain, photophobia, and loss of visual acuity. Anterior segment manifestations include bilateral acute uveitis with mutton-fat keratic precipitates and posterior segment findings include vitritis, multifocal neurosensory retinal detachment, choroiditis, optic nerve edema, and Dalen-Fuchs nodules. The diagnosis is clinical. Ancillary investigations include fundus fluorescein angiography, indocyanine green angiography, optical coherence tomography (OCT), ultrasound B scan, and autofluorescence imaging. The management options include corticosteroids (topical and systemic) as the first line along with immunomodulatory therapy started at the presentation of the disease. Recent advances include imaging with OCT-angiography, enhanced depth imaging-OCT (EDI-OCT, choroidal vascular index/CVI), targeting IL-23/IL-17 pathway, and use of biologics for the management of this rare entity. Recent advances in early diagnosis and prompt treatment has led to improved final visual outcomes in both the sympathizing and exciting eye. This review is aimed at giving a comprehensive overview of sympathetic ophthalmia along with a special emphasis on current treatment strategies and recent advances.

The Ruptured Globe, Sympathetic Ophthalmia, and the 14-Day Rule

PURPOSE

Prophylactic enucleation of a ruptured globe with no light perception within 14 days of injury to prevent sympathetic ophthalmia (SO) has been an established dictum in academic teaching for more than 100 years. This treatment strategy was originally based on observation, speculation, and careful thought, but there was never any scientific proof. This review summarizes and updates the current state of our knowledge about globe rupture and SO, examines the origin and validity of the 14-day rule, and emphasizes the importance of trying to save the traumatized eye whenever possible.

METHODS

A comprehensive literature review of SO and globe rupture was performed.

RESULTS

SO is a rare disorder that may potentially occur following traumatic globe rupture as well as following a variety of other intraocular surgeries. Vitreoretinal surgery may be a more common cause than trauma according to some studies. SO may still occur despite having the eye removed within 14 days of the trauma. A variety of new medications including biologic agents are now available to treat SO with improved efficacy in suppressing the associated ocular inflammation and allowing retention of some useful vision. Removing the traumatized, blind eye may have other important psychological consequences associated with it that require consideration before eye removal is carried out. Retaining the blind, phthisical, disfigured eye avoids phantom vision and phantom pain associated with enucleation as well as providing a good platform to support and move an overlying prosthetic eye. Data on the occurrence of SO following evisceration and enucleation with and without predisposing factors confirms the exceedingly low risk.

CONCLUSION

Most civilian open globe injuries can be successfully repaired with modern, advanced microsurgical techniques currently available. Because of the exceedingly low risk of SO, even with the severity of open globe trauma during military conflicts being more devastating as a result of the blast and explosive injuries, today every attempt is made to primarily close the eye rather than primarily enucleate it, providing there is enough viable tissue to repair. The 14-day rule for eye removal after severe globe ruptures is not scientifically supported and does not always protect against SO, but the safe time period for prophylactic eye removal is not definitively known. In the exceptional cases where SO does occur, several new medications are now available that may help treat SO. We advocate saving the ruptured globe whenever possible and avoiding prophylactic enucleation to prevent the rare occurrence of SO. When an eye requires removal, evisceration is an acceptable alternative to enucleation in cases that do not harbor intraocular malignancy.

Photoreceptor cells and RPE contribute to the development of diabetic retinopathy

Diabetic retinopathy (DR) is a leading cause of blindness. It has long been regarded as vascular disease, but work in the past years has shown abnormalities also in the neural retina. Unfortunately, research on the vascular and neural abnormalities have remained largely separate, instead of being integrated into a comprehensive view of DR that includes both the neural and vascular components. Recent evidence suggests that the most predominant neural cell in the retina (photoreceptors) and the adjacent retinal pigment epithelium (RPE) play an important role in the development of vascular lesions characteristic of DR. This review summarizes evidence that the outer retina is altered in diabetes, and that photoreceptors and RPE contribute to retinal vascular alterations in the early stages of the retinopathy. The possible molecular mechanisms by which cells of the outer retina might contribute to retinal vascular damage in diabetes also are discussed. Diabetes-induced alterations in the outer retina represent a novel therapeutic target to inhibit DR.

The Ocular Protective Effects of Nano/Submicron Particles Prepared from Lycium barbarum Fruits Against Oxidative Stress in an Animal Model

Purpose: To investigate the antioxidative properties of Lycium barbarum (LB) fruits in the eyes and to study whether LB fruits prepared with new nanotechnology have stronger antioxidative effects. Methods: Fourteen days post-supplementation with milled or blended LB fruits, intravitreal paraquat (PQ) was injected into Wistar rats to create oxidative stress. After an additional 14-day supplementation with LB fruits, the rats were sacrificed. An electroretinogram (ERG) was performed to evaluate retinal function before and after the PQ injection. Expression levels of antioxidative responders' mRNA in retina were detected by reverse transcription-polymerase chain reaction. Superoxide dismutase (SOD) and glutathione reductase activity in the aqueous humor (AqH) were analyzed by ELISA. Immunohistochemistry was conducted to evaluate the morphological changes of retina and the levels of oxidative biomarkers. The levels of cell apoptosis were assessed by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The reactive oxygen species (ROS) levels in AqH were measured by chemiluminescence methods. Results: The murine eyes supplemented with LB fruits exhibited several changes compared with the control group. The ERGs revealed significant improvement in retinal function. The mRNA expression levels of oxidative responders were downregulated in the retinas. The ROS was significantly reduced in the retinas, but the SOD meaningfully increased in the AqH. Immunohistochemistry staining and TUNEL assays showed decreased incidences of oxidative biomarkers and apoptosis in the retinas. Milled LB fruits exhibited better antioxidative effects than blended fruits. Conclusions: Milled LB fruits demonstrated superior protection against oxidative threats than blended fruits. Thus, these fruits could be an inexpensive supplement for many oxidative stress-related ocular diseases.

MiRNA as biomarker for uveitis - A systematic review of the literature

AIM

A systematic review of miRNA profiling studies in uveitis.

METHODS

Literature search strategy - Pubmed central central database, using miRNA/microRNA and intraocular inflammation/uveitis as keywords.

RESULTS

We found twenty publications regarding the experimental and clinical use of miRNA in uveitis, published between 2011 and 2018.

CONCLUSION

The publications regarding the role of miRNA in uveitis are very scarce, but provide some valuable information about the potential new mechanisms in uveitis. Some of the identified miRNAs in different uveitis entities could serve as a biomarker of intraocular inflammation. Possible candidate miRNAs could be let-7e, miRNA-1, miR-9-3, miR-20a-5p, miR-23a, mir-29a-3p, miR-140-5p, miR-143, miR-146a and miR-146a-5p, miR-155, miR-182 and miR-182-5p, miR-196a2, miR-205, miR-223-3p, miR-301a. MiR-146a, miR-146a-5p, miR-155, miR-182, miR-223-3p, have been found to be possibly associated with uveitis disease in both, human and animal species.

Expression Profile of Cationic Amino Acid Transporters in Rats with Endotoxin-Induced Uveitis

Purpose. The transcellular arginine transportation via cationic amino acid transporter (CAT) is the rate-limiting step in nitric oxide (NO) synthesis, which is crucial in intraocular inflammation. In this study, CAT isoforms and inducible nitric oxide synthase (iNOS) expression was investigated in endotoxin-induced uveitis (EIU). Methods. EIU was induced in Lewis rats by lipopolysaccharide (LPS) injection. In the treatment group, the rats were injected intraperitoneally with the proteasome inhibitor bortezomib before EIU induction. After 24 hours, leukocyte quantification, NO measurement of the aqueous humor, and histopathological examination were evaluated. The expression of CAT isoforms and iNOS was determined by reverse transcription-polymerase chain reaction, western blotting, and immunofluorescence staining. Nuclear factor-kappa B (NF-κB) binding activity was evaluated by electrophoretic mobility shift assay. The mouse macrophage cell line RAW 264.7 was used to validate the in vivo findings. Results. LPS significantly stimulated iNOS, CAT-2A, and CAT-2B mRNA and protein expression but did not affect CAT-1 in EIU rats and RAW 264.7 cells. Bortezomib attenuated inflammation and inhibited iNOS, CAT-2A, and CAT-2B expression through NF-κB inhibition. Conclusions. CAT-2 and iNOS, but not CAT-1, are specifically involved in EIU. NF-κB is essential in the induction of CAT-2 and iNOS in EIU.

Sympathetic ophthalmia: to the twenty-first century and beyond

Sympathetic ophthalmia is a rare bilateral granulomatous inflammation that follows accidental or surgical insult to the uvea of one eye. Onset of sympathetic ophthalmia can be insidious or acute, with recurrent periods of exacerbation. Clinical presentation shows mutton-fat keratic precipitates, choroidal infiltrations, and Dalen-Fuchs nodules. Histopathology reveals diffuse or nodular granulomatous inflammation of the uvea. Prevention and treatment strategies for sympathetic ophthalmia are currently limited to two modalities, enucleation of the injured eye and immunosuppressive therapy, aimed at controlling inflammation. The etiology and pathophysiology of the disease is still unclear but is largely thought to be autoimmune in nature. Recent insight on the molecular pathology of the disease as well as developments in imaging technology have furthered both the understanding on the autoimmune process in sympathetic ophthalmia and the targeting of prevention and treatment strategies for the future.

Role of the retinal vascular endothelial cell in ocular disease

Retinal endothelial cells line the arborizing microvasculature that supplies and drains the neural retina. The anatomical and physiological characteristics of these endothelial cells are consistent with nutritional requirements and protection of a tissue critical to vision. On the one hand, the endothelium must ensure the supply of oxygen and other nutrients to the metabolically active retina, and allow access to circulating cells that maintain the vasculature or survey the retina for the presence of potential pathogens. On the other hand, the endothelium contributes to the blood-retinal barrier that protects the retina by excluding circulating molecular toxins, microorganisms, and pro-inflammatory leukocytes. Features required to fulfill these functions may also predispose to disease processes, such as retinal vascular leakage and neovascularization, and trafficking of microbes and inflammatory cells. Thus, the retinal endothelial cell is a key participant in retinal ischemic vasculopathies that include diabetic retinopathy and retinopathy of prematurity, and retinal inflammation or infection, as occurs in posterior uveitis. Using gene expression and proteomic profiling, it has been possible to explore the molecular phenotype of the human retinal endothelial cell and contribute to understanding of the pathogenesis of these diseases. In addition to providing support for the involvement of well-characterized endothelial molecules, profiling has the power to identify new players in retinal pathologies. Findings may have implications for the design of new biological therapies. Additional progress in this field is anticipated as other technologies, including epigenetic profiling methods, whole transcriptome shotgun sequencing, and metabolomics, are used to study the human retinal endothelial cell.

[Effects of peroxynitrite derived from nitric oxide on cultured bovine ocular explants]

INTRODUCTION

Several studies have reported a significant production of nitric oxide (NO) with peroxynitrite formation in the setting of intraocular inflammation. In a previous study, we showed the cytotoxic effect of nitrites and nitrates, stable metabolites of NO, on the various tissues forming the layers of the eye, with variable degrees of tissue sensitivity. This study aims to investigate the effect of peroxynitrite on whole ocular bovine explants in culture.

METHODS

Healthy ocular bovine eyes, obtained immediately upon enucleation, were dissected and samples were taken from the anterior and posterior segments, and then cultured in DMEM supplemented with 10% fetal bovine serum, 2mM L-glutamine and antibiotics. Cultures were treated with 3-morpholino-sydonimin N-ethyl-carbamide (SIN-1) (molecule which produces NO and superoxide anion O(2)(.-)) at varying concentrations (100 to 500 μM) over 24 hours. After incubation, the explants were fixed in 10% buffered formalin, and histological study was performed.

RESULTS

Most of the structures showed changes on tissue and cellular levels after incubation with the peroxynitrite donor and various responses depending on the concentration used. These observations reflect variable concentration-dependent tissue sensitivity. The epithelia (cornea, iris and ciliary process) showed high sensitivity in comparison with sclera, which developed greater resistance.

CONCLUSION

In all, our results indicate a deleterious effect of peroxynitrite on bovine ocular structures in vitro. This effect is proportional to the concentration used. These results corroborate those reported by other teams and suggest the role of peroxynitrite derived from NO in the ocular lesions observed in the setting of uveitis.

Immunopathologic processes in sympathetic ophthalmia as signified by microRNA profiling

PURPOSE

Recent discovery of microRNAs and their negative gene regulation have provided new understanding in the pathogenesis of inflammatory diseases. This study demonstrated microRNA expression profiling and their likely role in sympathetic ophthalmia, using formalin-fixed, paraffin embedded samples.

METHODS

Two groups of four enucleated globes (total eight globes) from patients with clinical and histopathological diagnosis of SO (experimental samples) and one group of four age-matched, noninflamed enucleated globes (control samples) were used. Human genome-wide microRNA PCR array was performed and results were subjected to bioinformatics calculation and P values stringency tests. The targets were searched using the recently published and periodically updated miRWalk software. Quantitative real-time PCR and immunohistochemical staining were performed to confirm the validated targets in the mRNA and in the protein levels, respectively.

RESULTS

No microRNA was significantly upregulated in SO, but 27 microRNAs were significantly downregulated. Among these, four microRNAs (hsa-miR-1, hsa-let-7e, hsa-miR-9, and hsa-miR-182) were known to be associated with the inflammatory signaling pathway. Only hsa-miR-9 has the validated targets, tumor necrosis factor-α, and nuclear factor kappa B1, which have been previously shown to be associated with mitochondrial oxidative stress-mediated photoreceptor apoptosis in eyes with SO.

CONCLUSIONS

Identification of altered levels of microRNAs by microRNA expression profiling may yield new insights into the pathogenesis of SO by disclosing specific microRNA signatures. In the future these may be targeted by synthetic microRNA mimic-based therapeutic strategies.

Mitochondrial oxidative stress initiates visual loss in sympathetic ophthalmia

The visual loss that occurs with sympathetic ophthalmia (SO) in the absence of recognizable retinal damage and inflammatory cell infiltration is an enigma. Experimental autoimmune uveoretinitis (EAU) is an animal model used to study human endogenous uveitis. Both innate and adaptive immune responses have been well studied in the photoreceptor damage mechanism of EAU. In our studies, in the early phase of EAU, proinflammatory molecules such as tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS) and the subsequent mitochondrial DNA damage, mitochondrial protein alteration, and mitochondrial dysfunction by oxidative stress were observed before retinal inflammatory cell infiltration. Our recent study shows the importance of Toll-like receptors (TLRs) in the production of proinflammatory molecules and the induction of mitochondrial oxidative stress. Thus, the innate immune responses occur first with the activation of TLRs; this activation upregulates proinflammatory molecules, leading to mitochondrial oxidative stress before retinal inflammatory cell infiltration and the subsequent adaptive immune responses. Like EAU, SO also results in photoreceptor mitochondrial oxidative damage without retinal inflammatory cell infiltration. Such damage was associated with TNF-α, TNF-α receptors, and iNOS expression in the photoreceptors, suggesting that this molecular mechanism without retinal inflammatory cell infiltration may initiate photoreceptor damage in SO.

Challenges of managing sympathetic ophthalmia in a young child and the role of infliximab

The authors report the difficult challenges and use of infliximab in the delayed presentation of a 2½-year-old boy with a penetrating eye injury from a small ballpoint pen that led to sympathetic ophthalmia.

[Anti-TNF-α treatment for uveitis. Analysis of the current situation]

Biologicals are selectively acting proteins that demonstrated high efficacy in the treatment of chronic disorders. In particular, biologicals blocking tumor necrosis factor α (TNF-α), an essential cytokine in chronic inflammatory diseases, have demonstrated great promise. Experimental and clinical data indicate that TNF-α plays an important role in intraocular inflammation. Neutralization of TNF-α might therefore be a promising strategy for prevention and treatment of uveitis. Here we review the principle effects, therapeutic value, and potential side effects of anti-TNF agents in uveitis.

Peroxynitrite-induced expression of inducible nitric oxide synthase and activated apoptosis via nuclear factor-kappa B pathway in retinal pigment epithelial cells and antagonism of cholecystokinin octapeptide-8 in vitro

AIM

To explore that if peroxynitrite induced the expression of inducible nitric oxide synthase (iNOS)via nuclear factor-kappa B (NF-κB) pathway in retinal pigment epithelial (RPE) cells and the antagonism of cholecystokinin octapeptide-8 (Melatonin, CCK-8) in vitro.

METHODS

RPE cells were obtained from eyes of C57BL/6 mouse and divided into control, peroxynitrite and CCK-8 groups. Control group was treated with saline, peroxynitrite group was treated with peroxynitrite, and CCK-8 group was treated with CCK-8 after added with peroxynitrite. All changes were observered at 6, 12 and 24 hours after treatment. Gene array analysis, Reverse Transcription Polymerase Chain Reaction (RT-PCR) were used to determine the expression of inducible nitric oxide synthase (iNOS) mRNA in RPE cells. Western blotting was used to test the apoptosis of RPE cells. Immunofluorescent staining was used to determine the NF-κB pathway signal transduction.

RESULTS

Compared to the control group, the expression of iNOS mRNA was up-regulated in peroxynitrite group and down-regulated in CCK-8 group with gene array analysis. Apoptosis was increased in peroxynitrite group and decreased in CCK-8 group with western blotting. The NF-κB pathway signal transduction was more and more stronger in the peroxynitrite group. But in CCK-8 group, little stronger could be observed at 12 hours, then weak at 24 hours with immunofluorescent staining (P<0.001).

CONCLUSION

This study suggested that apoptosis of RPE cells was partly induced by peroxynitrite, which may be the new way of oxidative damage to the RPE cells. The NF-κB signal transduction may affect and reinforce apoptosis mediated by peroxynitrite. CCK-8 decreased apoptosis of RPE cells induced by peroxynitrite and is a potential agent for therapy of retinopathy. The mechanism of CCK-8 dealing with RPE cells may be related to its direct inhibition of the formation of iNOS to produce peroxynitrite and antagnism of damage of peroxynitrite to the RPE cells.

Oxidative photoreceptor cell damage in autoimmune uveitis

Uveitis comprises an extensive array of intraocular inflammatory diseases and often results in irreversible visual loss. Experimental autoimmune uveitis (EAU) is an animal model used to study human uveitis. Both innate and adaptive immune responses are known to mediate retinal damage in EAU. The innate immune response occurs first with activation of toll-like receptors which upregulate inflammatory cytokines, leading to oxidative stress; subsequently, the adaptive immune response results in inflammatory cytokine upregulation and mitochondrial oxidative stress. In early EAU, mitochondrial DNA is damaged before inflammatory cellular infiltration and alters mitochondrial protein levels and the functions of mitochondria in AU. Our recent study confirms the importance of TLR4 in the generation of inflammatory cytokines, initiation of oxidative DNA damage, and induction of mitochondrial oxidative stress. Like EAU, sympathetic ophthalmia also results in photoreceptor mitochondrial oxidative damage. Agents that prevent mitochondrial oxidative stress and photoreceptor apoptosis may help prevent retinal damage and preserve vision in uveitis.