Exosomes derived from mesenchymal stem cells

The functional mechanisms of mesenchymal stem cells (MSCs) have become a research focus in recent years. Accumulating evidence supports the notion that MSCs act in a paracrine manner. Therefore, the biological factors in conditioned medium, including exosomes and soluble factors, derived from MSC cultures are being explored extensively. The results from most investigations show that MSC-conditioned medium or its components mediate some biological functions of MSCs. Several studies have reported that MSC-derived exosomes have functions similar to those of MSCs, such as repairing tissue damage, suppressing inflammatory responses, and modulating the immune system. However, the mechanisms are still not fully understood and the results remain controversial. Compared with cells, exosomes are more stable and reservable, have no risk of aneuploidy, a lower possibility of immune rejection following in vivo allogeneic administration, and may provide an alternative therapy for various diseases. In this review, we summarize the properties and biological functions of MSC-derived exosomes and discuss the related mechanisms.

Effects of Mesenchymal Stem Cell-Derived Exosomes on Experimental Autoimmune Uveitis

We previously demonstrated that mesenchymal stem cells (MSCs) ameliorated experimental autoimmune uveoretinitis (EAU) in rats. Recently, MSC-derived exosomes (MSC-Exo) were thought to carry functions of MSCs. In this study, we tested the effect of local administration of human MSC-Exo on established EAU in the same species. Rats with EAU induced by immunization with interphotoreceptor retinol-binding protein 1177-1191 peptide were treated by periocular injections of increasing doses of MSC-Exo starting at the disease onset for 7 consecutive days. The in vitro effects of MSC-Exo on immune cell migration and responder T cell proliferation were examined by chemotactic assays and lymphocyte proliferation assays, respectively. We found that MSC-Exo greatly reduced the intensity of ongoing EAU as their parent cells by reducing the infiltration of T cell subsets, and other inflammatory cells, in the eyes. Furthermore, the chemoattractive effects of CCL2 and CCL21 on inflammatory cells were inhibited by MSC-Exo. However, no inhibitory effect of MSC-Exo on IRBP-specific T cell proliferation was observed. These results suggest that MSC-Exo effectively ameliorate EAU by inhibiting the migration of inflammatory cells, indicating a potential novel therapy of MSC-Exo for uveitis.

Exosomes derived from MSCs ameliorate retinal laser injury partially by inhibition of MCP-1

Although accumulated evidence supports the notion that mesenchymal stem cells (MSCs) act in a paracrine manner, the mechanisms are still not fully understood. Recently, MSC-derived exosomes (MSC-Exos), a type of microvesicle released from MSCs, were thought to carry functional proteins and RNAs to recipient cells and play therapeutic roles. In the present study, we intravitreally injected MSCs derived from either mouse adipose tissue or human umbilical cord, and their exosomes to observe and compare their functions in a mouse model of laser-induced retinal injury. We found that both MSCs and their exosomes reduced damage, inhibited apoptosis, and suppressed inflammatory responses to obtain better visual function to nearly the same extent in vivo. Obvious down-regulation of monocyte chemotactic protein (MCP)-1 in the retina was found after MSC-Exos injection. In vitro, MSC-Exos also down-regulated MCP-1 mRNA expression in primarily cultured retinal cells after thermal injury. It was further demonstrated that intravitreal injection of an MCP-1-neutralizing antibody promoted the recovery of retinal laser injury, whereas the therapeutic effect of exosomes was abolished when MSC-Exos and MCP-1 were administrated simultaneously. Collectively, these results suggest that MSC-Exos ameliorate laser-induced retinal injury partially through down-regulation of MCP-1.

Cytokines that Modulate the Differentiation of Th17 Cells in Autoimmune Uveitis

Increasing evidence has suggested that T helper 17 (Th17) cells play a central role in the pathogenesis of ocular immune disease. The association between pathogenic Th17 cells and the development of uveitis has been confirmed in experimental and clinical studies. Several cytokines affect the initiation and stabilization of the differentiation of Th17 cells. Therefore, understanding the mechanism of related cytokines in the differentiation of Th17 cells is important for exploring the pathogenesis and the potential therapeutic targets of uveitis. This article briefly describes the structures, mechanisms, and targeted drugs of cytokines-including interleukin (IL)-6, transforming growth factor-β1 (TGF-β1), IL-1β, IL-23, IL-27, IL-35, IL-2, IL-4, IL-21, and interferon (IFN)-γ-which have an important influence on the differentiation of Th17 cells and discusses their potential as therapeutic targets for treating autoimmune uveitis.

Multi-omics analysis of human mesenchymal stem cells shows cell aging that alters immunomodulatory activity through the downregulation of PD-L1

Mesenchymal stem cells (MSCs) possess potent immunomodulatory activity and have been extensively investigated for their therapeutic potential in treating inflammatory disorders. However, the mechanisms underlying the immunosuppressive function of MSCs are not fully understood, hindering the development of standardized MSC-based therapies for clinical use. In this study, we profile the single-cell transcriptomes of MSCs isolated from adipose tissue (AD), bone marrow (BM), placental chorionic membrane (PM), and umbilical cord (UC). Our results demonstrate that MSCs undergo a progressive aging process and that the cellular senescence state influences their immunosuppressive activity by downregulating PD-L1 expression. Through integrated analysis of single-cell transcriptomic and proteomic data, we identify GATA2 as a regulator of MSC senescence and PD-L1 expression. Overall, our findings highlight the roles of cell aging and PD-L1 expression in modulating the immunosuppressive efficacy of MSCs and implicating perinatal MSC therapy for clinical applications in inflammatory disorders.

Long-term therapeutic effects of mesenchymal stem cells compared to dexamethasone on recurrent experimental autoimmune uveitis of rats

PURPOSE

We tested the long-term effects of different regimens of mesenchymal stem cell (MSC) administration in a recurrent experimental autoimmune uveitis (rEAU) model in rats, and compared the efficacy of MSC to that of dexamethasone (DEX).

METHODS

One or two courses of MSC treatments were applied to R16-specific T cell-induced rEAU rats before or after disease onsets. The DEX injections were given for 7 or 50 days continuously after disease onsets. Clinical appearances were observed until the 50th day after transfer. On the 10th day, T cells from control and MSC groups were analyzed by flow cytometry. Supernatants from the proliferation assay and aqueous humor were collected for cytokine detection. Functions of T cells and APCs in spleens also were studied by lymphocyte proliferation assays.

RESULTS

One course of MSC therapy, administered after disease onset, led to a lasting therapeutic effect, with a decreased incidence, reduced mean clinical score, and reduced retinal impairment after 50 days of observation, while multiple courses of treatment did not improve the therapeutic benefit. Although DEX and MSCs equally reduced the severity of the first episode of rEAU, the effect of DEX was shorter lasting, and DEX therapy failed to control the disease even with long periods of treatment. The MSCs significantly decreased T helper 1 (Th1) and Th17 responses, suppressed the function of antigen-presenting cells, and upregulated T regulatory cells.

CONCLUSIONS

These results suggested that MSCs might be new corticosteroid spring agents, while providing fewer side effects and longer lasting suppressive effects for recurrent uveitis.

Therapeutic effect of bone marrow mesenchymal stem cells on laser-induced retinal injury in mice

Stem cell therapy has shown encouraging results for neurodegenerative diseases. The retina provides a convenient locus to investigate stem cell functions and distribution in the nervous system. In the current study, we investigated the therapeutic potential of bone marrow mesenchymal stem cells (MSCs) by systemic transplantation in a laser-induced retinal injury model. MSCs from C57BL/6 mice labeled with green fluorescent protein (GFP) were injected via the tail vein into mice after laser photocoagulation. We found that the average diameters of laser spots and retinal cell apoptosis were decreased in the MSC-treated group. Interestingly, GFP-MSCs did not migrate to the injured retina. Further examination revealed that the mRNA expression levels of glial fibrillary acidic protein and matrix metalloproteinase-2 were lower in the injured eyes after MSC transplantation. Our results suggest that intravenously injected MSCs have the ability to inhibit retinal cell apoptosis, reduce the inflammatory response and limit the spreading of damage in the laser-injured retina of mice. Systemic MSC therapy might play a role in neuroprotection, mainly by regulation of the intraocular microenvironment.

Effect of small extracellular vesicles derived from IL-10-overexpressing mesenchymal stem cells on experimental autoimmune uveitis

BACKGROUND

Autoimmune uveitis is a sight-threatening intraocular inflammation mainly caused by immune dysregulation. The development of safe and effective therapeutic approaches is urgently needed. Small extracellular vesicles (sEVs) derived from mesenchymal stem cells (MSCs) have been demonstrated to inhibit autoimmune responses; however, the immunosuppressive effect of MSC-sEVs is too weak for clinical transfer. In the current study, we investigated the therapeutic effect of IL-10-overexpressing MSC-sEVs (sEV-IL10) on experimental autoimmune uveitis (EAU) and studied the underlying mechanism.

METHODS

Mice were randomly grouped and received a single tail vein injection of different sEVs (50 μg) or PBS on day 11 post-immunization. The clinical and histological scores were graded, and the percentage of T helper cell was measured. To investigate the effect of sEVs on the proliferation of T-cells and the differentiation of Th1, Th17 and Treg cells, T-cells were cocultured with sEVs under the corresponding culture conditions. After labeled with PKH-26, sEVs were traced both in vivo and in vitro.

RESULTS

Compared with normal or vector sEV-treated groups, mice in the sEV-IL10-treated group had lower clinical and histological scores with lower percentages of Th1 and Th17 cells in the eyes and higher percentages of Treg cells in the spleen and draining lymph nodes (LN). Furthermore, sEV-IL10 enhanced the suppressive effect of MSC-sEVs on the proliferation of T-cells and differentiation of Th1 and Th17 cells, whereas upregulated the differentiation of Treg cells. Both in vivo and in vitro experiments demonstrated that MSC-sEVs were rapidly enriched in target tissues and internalized by T-cells.

CONCLUSION

These results suggested that sEV-IL10 effectively ameliorates EAU by regulating the proliferation and differentiation of T-cells, indicating sEVs as a potential novel therapy for autoimmune uveitis or other autoimmune diseases.

Characteristics of syphilitic uveitis in northern China

BACKGROUND

To describe the characteristics of patients with syphilitic uveitis in northern China.

METHODS

A case series of 21 patients (33 eyes) diagnosed with syphilitic uveitis from 2011 to 2016 at a tertiary center in northern China was retrospectively analyzed.

RESULTS

Twenty-one patients (33 eyes) were diagnosed as syphilitic uveitis. Posterior segment involvement was found in 32 eyes (97.0%). Vitreous haze, neuroretinitis, and posterior placoid chorioretinitis were mainly found in patients with a relatively short duration of the disease, while diffuse chorioretinitis, pseudoretinitis pigmentosa, cystoid macular edema, and epiretinal membrane were found in patients with relatively long duration of ocular involvement. A low best-corrected visual acuity (P = 0.022) and a delay of syphilis treatment (P < 0.001) were associated with a significantly worse visual outcome.

CONCLUSIONS

Syphilitic uveitis should be included in the differential diagnosis of any form of posterior ocular inflammation. The pattern of ocular involvement may change with the disease progression.

Author Correction: Effects of Mesenchymal Stem Cell-Derived Exosomes on Experimental Autoimmune Uveitis

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Therapeutic effects of mesenchymal stem cells administered at later phase of recurrent experimental autoimmune uveitis

AIM

To test the therapeutic effects of delayed treatment of mesenchymal stem cells (MSCs) in recurrent experimental autoimmune uveitis (rEAU).

METHODS

The efficacy of different regimens of MSC administration in rEAU were tested by evaluation of clinical and pathological intraocular inflammation, as well as retinal structural and functional integrity using optical coherence tomography (OCT) and electroretinogram (ERG). The retinal sections were also immunostained with antibodies to glial fibrillary acidic protein (GFAP) and rhodopsin (RHO).

RESULTS

Delayed treatment of MSCs effectively alleviated the severity of intraocular inflammation with relative intact of outer retinal structure and function. Moreover, double therapies with longer interval led to an even better clinical evaluation, as well as a trend of decrease in relapse and amelioration of retinal function. MSC therapies also effectively reduced GFAP expression and increased RHO expression in the retina.

CONCLUSION

MSC administration can effectively treat developed diseases of rEAU, and multiple therapies can provide additional therapeutic benefits.

Mesenchymal-Stem-Cell-Based Strategies for Retinal Diseases

Retinal diseases are major causes of irreversible vision loss and blindness. Despite extensive research into their pathophysiology and etiology, pharmacotherapy effectiveness and surgical outcomes remain poor. Based largely on numerous preclinical studies, administration of mesenchymal stem cells (MSCs) as a therapeutic strategy for retinal diseases holds great promise, and various approaches have been applied to the therapies. However, hindered by the retinal barriers, the initial vision for the stem cell replacement strategy fails to achieve the anticipated effect and has now been questioned. Accumulating evidence now suggests that the paracrine effect may play a dominant role in MSC-based treatment, and MSC-derived extracellular vesicles emerge as a novel compelling alternative for cell-free therapy. This review summarizes the therapeutic potential and current strategies of this fascinating class of cells in retinal degeneration and other retinal dysfunctions.

Rapamycin ameliorates experimental autoimmune uveoretinitis by inhibiting Th1/Th2/Th17 cells and upregulating CD4+CD25+ Foxp3 regulatory T cells

AIM

To determine the effects of rapamycin on experimental autoimmune uveoretinitis (EAU) and investigate of role of rapamycin on T cell subsets in the disease.

METHODS

EAU was induced in rats using peptides 1169 to 1191 of the interphotoreceptor binding protein (IRBP). Rapamycin (0.2 mg/kg/d) was administrated by intraperitoneal injection for a consecutive 7d after immunization. Th1/Th2/Th17 cytokines, TGF-β1, and IL-6 produced by lymphocyteswere measured by ELISA, while Th17 cells and CD4+CD25+ regulatory T cells (Tregs) from rat spleen were detected by flow cytometry.

RESULTS

Intraperitoneal treatment immediately after immunization dramatically ameliorated the clinical course of EAU. Clinical responses were associated with reduced retinal inflammatory cell infiltration and tissue destruction. Rapamycin induced suppression of Th1/Th2/Th17 cytokines, including IFN-γ, IL-2, IL-17, IL-4, and IL-10 release from T lymphocytes of EAU rats, in vitro. Rapamycin also significantly increased TGF-β1 production but had no effect on IL-6 productionof T lymphocytes from EAU rats in vitro. Furthermore, rapamycin decreased the ratio of Th17 cells/CD4+T cells and upregulated Tregs in EAU, as detected by flow cytometry.

CONCLUSION

Rapamycin effectively interferes with T cell mediated autoimmune uveitis by inhibiting antigen-specific T cell functions and enhancing Tregs in EAU. Rapamycin is a promising new alternative as an adjunct corticosteroid-sparing agent for treating uveitis.

Comprehensive profiling of extracellular vesicles in uveitis and scleritis enables biomarker discovery and mechanism exploration

BACKGROUND

Uveitis and posterior scleritis are sight-threatening diseases with undefined pathogenesis and accurate diagnosis remains challenging.

METHODS

Two plasma-derived extracellular vesicle (EV) subpopulations, small and large EVs, obtained from patients with ankylosing spondylitis-related uveitis, Behcet's disease uveitis, Vogt-Koyanagi-Harada syndrome, and posterior scleritis were subjected to proteomics analysis alongside plasma using SWATH-MS. A comprehensive bioinformatics analysis was performed on the proteomic profiles of sEVs, lEVs, and plasma. Candidate biomarkers were validated in a new cohort using ELISA. Pearson correlation analysis was performed to analyze the relationship between clinical parameters and proteomic data. Connectivity map database was used to predict therapeutic agents.

RESULTS

In total, 3,668 proteins were identified and over 3000 proteins were quantified from 278 samples. When comparing diseased group to healthy control, the proteomic profiles of the two EV subgroups were more correlated with disease than plasma. Comprehensive bioinformatics analysis highlighted potential pathogenic mechanisms for these diseases. Potential biomarker panels for four diseases were identified and validated. We found a negative correlation between plasma endothelin-converting enzyme 1 level and mean retinal thickness. Potential therapeutic drugs were proposed, and their targets were identified.

CONCLUSIONS

This study provides a proteomic landscape of plasma and EVs involved in ankylosing spondylitis-related uveitis, Behcet's disease uveitis, Vogt-Koyanagi-Harada syndrome, and posterior scleritis, offers insights into disease pathogenesis, identifies valuable biomarker candidates, and proposes promising therapeutic agents.

Mechanism of action of platinum nanoparticles implying from antioxidant to metabolic programming in light-induced retinal degeneration model

Photoreceptors (PRs) degeneration is central to visual impairment and loss in most blind retinal diseases, including age-related macular disease (AMD) and diabetic retinopathy (DR). PRs are susceptible to oxidative stress owing to their unique metabolic features. Accumulating evidence has demonstrated that the targeting oxidative stress is a promising treatment strategy for PR degeneration. Herein, we introduced potent antioxidative platinum nanoparticles (Pt NPs) to treat PRs degeneration in this study. The Pt NPs exhibited multi-enzymatic antioxidant activity and protected PRs from H2O2-induced oxidative damage in vitro assays. Based on the same mechanism, the intravitreal injection of Pt NPs significantly reduced cell apoptosis, maintained retinal structure and preserved retinal function in a mouse model of light-induced retinal degeneration (LIRD). Most importantly, the results of RNA sequencing showed that the transcription of antioxidative genes was upregulated, and metabolic reprogramming occurred in the LIRD-retina after treatment with Pt NPs, both of which benefited retinal survival from oxidative damage. The results indicated that Pt NPs were indeed potent therapeutic candidates for PRs degeneration in blind retinal diseases.

Enhanced therapeutic effect of PEDF-loaded mesenchymal stem cell-derived small extracellular vesicles against oxygen-induced retinopathy through increased stability and penetrability of PEDF

BACKGROUND

Several common retinal diseases that cause blindness are characterised by pathological neovascularisation accompanied by inflammation and neurodegeneration, including retinopathy of prematurity (ROP), diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinal vein occlusion (RVO). The current treatment strategies for these diseases have limited benefits. Thus, safer and more effective alternative approaches are required. In this study, we loaded small extracellular vesicles (sEVs) derived from mesenchymal stem cell (MSC) with pigment epithelium-derived factor (PEDF), and tested the therapeutic effect of PEDF-loaded sEVs (PEDF-sEVs) using an oxygen induced retinopathy (OIR) mouse model, aiming to establish a new therapy strategy for the treatment of retinal pathological angiogenesis.

RESULTS

We formulated PEDF-loaded sEVs (PEDF-sEVs) containing high concentrations of PEDF and evaluated their effects through in vivo and in vitro experiments. In OIR mice, PEDF-sEVs showed significantly better effects on retinal avascular areas, inflammation, and neuronal degeneration compared with the anti-vascular endothelial growth factor (VEGF) drug, which may indicate a possible advantage of PEDF-sEVs over anti-VEGF drugs in the treatment of pathological neovascularisation. In vitro, PEDF-sEVs greatly inhibited endothelial cell (EC) proliferation, migration, and tube formation by suppressing the VEGF-induced phosphorylation of extracellular signal-regulated kinase (ERK) and AKT (also known as Protein Kinase B). All experiments and analyses were performed in triplicate. PEDF-sEVs were more effective than PEDF or sEVs alone, both in vitro and in vivo. Furthermore, to determine the distribution of PEDF-sEVs, we used DiD-labelled sEVs and FITC-labelled PEDF to track the sEVs and PEDF, respectively. We found that PEDF-sEVs effectively reduced the degradation of PEDF.

CONCLUSIONS

Loading PEDF on sEVs effectively enhanced the anti-angiogenic, anti-inflammatory, and neuroprotective effects of PEDF by increasing the stability and penetrability. These results suggest a potential role for PEDF-sEVs in retinal pathological neovascularisation.

Biometric indicators of anterior segment parameters before and after laser peripheral iridotomy by swept-source optical coherent tomography

BACKGROUND

Primary angle closure glaucoma (PACG) is the most common type of glaucoma in China. Laser peripheral iridotomy (LPI) is the primary choice to treat PAC: We aim to evaluate the changes of biometric parameters of anterior segment and to find possible biometric predictors of the effect of laser peripheral iridotomy (LPI) in primary angle closure (PAC) eyes using swept-source optical coherent tomography (OCT).

METHODS

LPI was performed in 52 PAC eyes of 28 participants. The change of intraocular pressure and anterior segment parameters, including angle opening distance (AOD500), AOD500 area, trabecular iris space area (TISA500), TISA500 volume, trabecular iris angle (TIA500), iridotrabecular contact (ITC) index, ITC area, anterior chamber volume (ACV), anterior chamber depth (ACD), lens vault (LV) and lens thickness (LT) before and 1 week after LPI were measured by Tomey CASIA2 anterior segment OCT. We also estimate and analyze potential associated factors possibly affecting the change of anterior chamber parameters.

RESULTS

No post-laser complications were found. The ACD, LV and LT did not change significantly 1 week after LPI. AOD500, AOD500 area, TISA500, TISA500 volume, TIA500, ACV increased significantly after LPI. There was significant decrease in ITC index and ITC area. LT was positively correlated to the change of ITC index (β = 0.239, *p = 0.045).

CONCLUSIONS

The anterior segment architecture significantly changed after LPI in PAC spectrum eyes. Crystalline lens measurements remained unchanged before and after LPI. AS-OCT can be used to follow anterior chamber parameter changes in PAC spectrum eyes. LT may play a role in the therapeutic effect of LPI.

Pertussis toxin-induced inhibition of Wnt/β-catenin signaling in dendritic cells promotes an autoimmune response in experimental autoimmune uveitis

BACKGROUND

Previous reports have indicated that disrupting the Wnt/β-catenin pathway in dendritic cells (DCs) may affect the progression of autoimmune inflammation; however, the factors and timing that regulate Wnt/β-catenin signaling have not been clearly understood.

METHODS

Experimental autoimmune uveitis (EAU) mice and Vogt-Koyanagi-Harada disease (VKH) patient samples were used to detect the expression of Wnt/β-catenin pathway genes. Western blot, real-time PCR, flow cytometry, and ELISA were performed to examine the expression of components of the Wnt/β-catenin pathway and inflammatory factors. DC-specific β-catenin knockout mice and 6-bromoindirubin-3'-oxime (BIO) administered mice were used to observe the effect of disrupting the Wnt pathway on EAU pathogenesis.

RESULTS

Wnt/β-catenin signaling was inhibited in DCs during the induction phase of EAU. The inhibition was mediated by pertussis toxin (PTX), which promoted DC maturation, in turn promoting pathogenic T cell proliferation and differentiation. In vivo experiments confirmed that deleting β-catenin in DCs enhanced EAU severity, and pre-injection of PTX advanced EAU onset. Administration of a Wnt activator (BIO) limited the effects of PTX, in turn ameliorating EAU.

CONCLUSIONS

Our results demonstrate that PTX plays a key role as a virulence factor in initiating autoimmune inflammation via DCs by inhibiting Wnt/β-catenin signaling in EAU, and highlight the potential mechanism by which infection can trigger apparent autoimmunity.

New-onset or relapse of uveitis after rapid spreading of COVID-19 infection in China and risk factor analysis for relapse

BACKGROUND

The aim of this study was to report the clinical profile of new-onset and relapse of uveitis following rapid spreading of coronavirus disease 2019 (COVID-19) infection due to change of anti-COVID-19 policies in China and investigate potential risk factors for inflammation relapse.

METHODS

In this retrospective case-control study, patients with new-onset or a history of uveitis between December 23, 2022, and February 28, 2023, were included to assess the influence of COVID-19 infection on uveitis. Detailed information on demographic data, clinical characteristics, treatment measures, treatment response, and ocular inflammatory status before and after COVID-19 infection was collected.

RESULTS

This study included 349 patients with a history of uveitis. The uveitis relapse rate was higher (28.8%, n = 288) in those with COVID-19 infection than in patients without COVID-19 infection (14.8%, n = 61) (P = 0.024). Among the relapse cases, 50.8% experienced a relapse of anterior uveitis, while 49.2% had a relapse of uveitis involving the posterior segment. Multivariable regression analysis indicated a positive correlation between disease duration and uveitis relapse, while the last relapse exceeding one year before COVID-19 infection and the use of methotrexate during COVID-19 infection were negatively correlated with relapse of uveitis. Thirteen patients who developed new-onset uveitis following COVID-19 infection were included; among them, three (23.1%) had anterior uveitis and 10 (76.9%) had uveitis affecting the posterior segment. Regarding cases involving the posterior segment, four patients (30.8%) were diagnosed with Vogt-Koyanagi-Harada disease.

CONCLUSIONS

COVID-19 infection increases the rate of uveitis relapse. Long disease duration is a risk factor, while time since the last relapse more than 1 year and methotrexate use are protective factors against uveitis relapse.

HIGH LONG-TERM DRUG-FREE REMISSION RATE FOR ACUTE VOGT-KOYANAGI-HARADA DISEASE WITH AN APPROPRIATE IMMUNOSUPPRESSIVE REGIMEN

PURPOSE

To report the clinical profile and outcomes of acute Vogt-Koyanagi-Harada disease with a strict immunosuppression regimen and investigate the risk factors for a prolonged disease course.

METHODS

A total of 101 patients with acute Vogt-Koyanagi-Harada (202 eyes) with more than 24 months of follow-up were recruited from January 2011 to June 2020. They were divided into two groups according to the interval between the onset of Vogt-Koyanagi-Harada and treatment. Oral prednisone was gradually tapered off by a diminished dose according to a relatively strict protocol. Patient responses to the treatment regimen were classified as long-term drug-free remission or chronic recurrent.

RESULTS

Ninety-six patients (95.0%) achieved long-term drug-free remission without recurrence, while 5 (5.0%) had chronic recurrence. Most patients achieved good best-corrected visual acuity (90.6% ≧20/25). A generalized estimation equation model demonstrated that time of visit, ocular complications, and cigarette smoking were independent risk factors for a longer disease course, and smokers required a higher drug dose and longer treatment course than nonsmokers.

CONCLUSION

An immunosuppressive regimen with an appropriate tapering speed can lead to long-term drug-free remission in patients with acute Vogt-Koyanagi-Harada. Cigarette smoking significantly affects ocular inflammation.

Comprehensive Proteomic Profiling of Aqueous Humor in Idiopathic Uveitis and Vogt-Koyanagi-Harada Syndrome

Idiopathic uveitis (IU) and Vogt-Koyanagi-Harada (VKH) syndrome are common types of uveitis. However, the exact pathological mechanisms of IU and VKH remain unclear. Proteomic analysis of aqueous humor (AH), the most easily accessible intraocular fluid and a key site of uveitis development, may reveal potential biomarkers and elucidate uveitis pathogenesis. In this study, 44 AH samples, including 12 IU cases, 16 VKH cases, and 16 controls, were subjected to label-free quantitative proteomic analysis. We identified 557 proteins from a comprehensive spectral library of 634 proteins across all samples. The AH proteomic profiles of the IU and VKH groups were different from those of the control group. Differential analysis revealed a shared pattern of extracellular matrix disruption and downregulation of retinal cellular proteins in the IU and VKH groups. Enrichment analysis revealed a protein composition indicative of inflammation in the AH of the IU and VKH groups but not in that of the control group. In the IU and VKH groups, innate immunity played an important role, as indicated by complement cascade activation and overexpression of innate immune cell markers. Extreme gradient boosting (XGBoost), an efficient and robust machine learning algorithm, was subsequently used to screen potential biomarkers for classifying the IU, VKH, and control groups. Transferrin and complement factor B were deemed the most important and represent a promising biomarker panel. These proteins were validated by high-resolution multiple reaction monitoring (HR-MRM) in an independent validation cohort. A classification decision tree was subsequently built for the diagnosis. Our findings further the understanding of the underlying molecular mechanisms in IU and VKH and facilitate the development of potential therapeutic and diagnostic strategies.

Small extracellular vesicles derived from microRNA-22-3p-overexpressing mesenchymal stem cells protect retinal ganglion cells by regulating MAPK pathway

Glaucoma is the leading cause of irreversible blindness and is characterized by progressive retinal ganglion cell (RGC) loss and retinal nerve fiber layer thinning. Currently, no existing treatment is effective for the preservation of RGCs. MicroRNA-22-3p (miR22) and small extracellular vesicles derived from mesenchymal stem cells (MSC-sEVs) have neuroprotective effects. In this study, we apply miR22-overexpressing MSC-sEVs in an N-methyl-D-aspartic acid (NMDA)-induced RGC injury model to assess their short-term therapeutic effects and explore the underlying mechanisms. We find that mice in the miR22-sEVs-treated group have thicker retinas, fewer apoptotic cells, more reserved RGCs, better retinal function, and lower expression levels of Bax and caspase-3. MiR22-sEVs treatment promotes viability, inhibits apoptosis and inhibits Bax and caspase-3 expression in RGC-5 cells. MiR22 targets mitogen-activated protein kinase kinase kinase 12 to inhibit apoptosis by regulating the mitogen-activated protein kinase (MAPK) signaling pathway. Collectively, our results suggest that miR22-sEVs ameliorate NMDA-induced RGC injury through the inhibition of MAPK signaling pathway-mediated apoptosis, providing a potential therapy for glaucoma and other diseases that involve RGC damage.

Clinical characteristics and outcomes of acute retinal necrosis at different stages: a retrospective study

BACKGROUND

To examine the clinical features and treatment outcomes of patients with acute retinal necrosis (ARN) at different disease stages and identify the risk factors associated with a poor prognosis.

METHODS

This retrospective study included 39 patients (44 eyes) with ARN who were treated at a single center. The eyes were divided into three stages based on the ocular findings and clinical course at the initial diagnosis. The main outcome measures were the incidence of retinal detachment (RD) and final visual acuity (VA). Regression analyses were performed to investigate the risk factors associated with the main outcomes.

RESULTS

Nine, 10, and 25 eyes were in the early, middle, and late stages, respectively. Eyes in the early stage had the shortest symptom duration (P = 0.019). At the first visit, the intraocular pressure (IOP) was elevated in half the patients; 29 eyes (65.9%) had keratic precipitates (KPs) and five (11.6%) had iris nodules. The final VA improved in early-stage eyes (P = 0.008) and decreased in late-stage eyes (P = 0.004) after treatment. RD was not common with early diagnosis. Five (50%) and 17 (68%) eyes in the middle and late stages developed RD, respectively. Independent predictors of RD included the vitritis grade (P = 0.046) and clock hours of retinitis (P = 0.045). Initial VA at presentation (β = 0.291, P = 0.009), the occurrence of RD (β = 0.209, P = 0.033), and clock hours of retinitis (β = 0.323, P = 0.008) were identified as associated with final VA.

CONCLUSION

Early diagnosis and treatment are associated with positive clinical outcomes. Anterior segment signs (e.g., mildly or moderately elevated IOP, KPs, and iris nodules) are important for early diagnosis.

Developing the biomarker panels and drugs by proteomic analysis for autoimmune uveitis and posterior scleritis

Autoimmune uveitis and posterior scleritis are ocular diseases caused by immune dysregulation. Their pathogenesis remains elusive, and delayed diagnosis can exacerbate vision loss. Our study analyzed proteomic profiles of 190 patients with Behcet's disease uveitis, posterior scleritis, and Vogt-Koyanagi-Harada syndrome. Bioinformatics methods revealed potential pathogenesis and biomarkers for the diseases, which were verified by enzyme-linked immunosorbent assay. The diagnostic accuracy was improved by constructing a biomarker combination. In addition, we used the Connectivity Map tool to analyze the differentially expressed proteins and identified small molecules with potential clinical applications. In this study, EMINIL1 and LYZ were identified as biomarkers for Behcet's uveitis, GSTP1 and PGLYRP1 for posterior scleritis, and APOH and STXBP1 for Vogt-Koyanagi-Harada syndrome. This study mapped the plasma proteins of these diseases, revealing potential pathogenesis and clinical applications of these biomarkers.

Enhanced immunosuppressive capability of mesenchymal stem cell-derived small extracellular vesicles with high expression of CD73 in experimental autoimmune uveitis

BACKGROUND

Autoimmune uveitis is an inflammatory disease triggered by an aberrant immune response. Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) are emerging as potential therapeutic agents for this condition. CD73, an ectoenzyme present on MSC-sEVs, is involved in mitigating inflammation by converting extracellular adenosine monophosphate into adenosine. We hypothesize that the inhibitory effect of MSC-sEVs on experimental autoimmune uveitis (EAU) could be partially attributed to the surface expression of CD73.

METHODS

To investigate novel therapeutic approaches for autoimmune uveitis, we performed lentiviral transduction to overexpress CD73 on the surface of MSC-sEVs, yielding CD73-enriched MSC-sEVs (sEVs-CD73). Mice with interphotoreceptor retinoid-binding protein (IRBP)-induced EAU were grouped randomly and treated with 50 µg MSC-sEVs, vector infected MSC-sEVs, sEVs-CD73 or PBS via single tail vein injection. We evaluated the clinical and histological features of the induced mice and analyzed the proportion and functional capabilities of T helper cells. Furthermore, T-cells were co-cultured with various MSC-sEVs in vitro, and we quantified the resulting inflammatory response to assess the potential therapeutic benefits of sEVs-CD73.

RESULTS

Compared to MSC-sEVs, sEVs-CD73 significantly alleviates EAU, leading to reduced inflammation and diminished tissue damage. Treatment with sEVs-CD73 results in a decreased proportion of Th1 cells in the spleen, draining lymph nodes, and eyes, accompanied by an increased proportion of regulatory T-cells (Treg cells). In vitro assays further reveal that sEVs-CD73 inhibits T-cell proliferation, suppresses Th1 cells differentiation, and enhances Treg cells proportion.

CONCLUSION

Over-expression of CD73 on MSC-sEVs enhances their immunosuppressive effects in EAU, indicating that sEVs-CD73 has the potential as an efficient immunotherapeutic agent for autoimmune uveitis.