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Retinal glycoprotein enrichment by concanavalin a enabled identification of novel membrane autoantigen synaptotagmin-1 in equine recurrent uveitis.

ABSTRACT: Complete knowledge of autoantigen spectra is crucial for understanding pathomechanisms of autoimmune diseases like equine recurrent uveitis (ERU), a spontaneous model for human autoimmune uveitis. While several ERU autoantigens were identified previously, no membrane protein was found so far. As there is a great overlap between glycoproteins and membrane proteins, the aim of this study was to test whether pre-enrichment of retinal glycoproteins by ConA affinity is an effective tool to detect autoantigen candidates among membrane proteins. In 1D Western blots, the glycoprotein preparation allowed detection of IgG reactions to low abundant proteins in sera of ERU patients. Synaptotagmin-1, a Ca2+-sensing protein in synaptic vesicles, was identified as autoantigen candidate from the pre-enriched glycoprotein fraction by mass spectrometry and was validated as a highly prevalent autoantigen by enzyme-linked immunosorbent assay. Analysis of Syt1 expression in retinas of ERU cases showed a downregulation in the majority of ERU affected retinas to 24%. Results pointed to a dysregulation of retinal neurotransmitter release in ERU. Identification of synaptotagmin-1, the first cell membrane associated autoantigen in this spontaneous autoimmune disease, demonstrated that examination of tissue fractions can lead to the discovery of previously undetected novel autoantigens. Further experiments will address its role in ERU pathology.

SUBMITTER: Swadzba ME

PROVIDER: S-EPMC3517615 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Retinal glycoprotein enrichment by concanavalin a enabled identification of novel membrane autoantigen synaptotagmin-1 in equine recurrent uveitis.

Swadzba Margarete E ME Hauck Stefanie M SM Naim Hassan Y HY Amann Barbara B Deeg Cornelia A CA

PloS one 20121207 12

Complete knowledge of autoantigen spectra is crucial for understanding pathomechanisms of autoimmune diseases like equine recurrent uveitis (ERU), a spontaneous model for human autoimmune uveitis. While several ERU autoantigens were identified previously, no membrane protein was found so far. As there is a great overlap between glycoproteins and membrane proteins, the aim of this study was to test whether pre-enrichment of retinal glycoproteins by ConA affinity is an effective tool to detect aut ...[more]

PMID: 23236410

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Project description:PurposeTo evaluate the risk of and risk factors for retinal neovascularization (NV) in cases of uveitis.DesignRetrospective cohort study.ParticipantsPatients with uveitis at 4 US academic ocular inflammation subspecialty practices.MethodsData were ascertained by standardized chart review. Prevalence data analysis used logistic regression. Incidence data analysis used survival analysis with time-updated covariates where appropriate.Main outcome measuresPrevalence and incidence of NV.ResultsAmong uveitic eyes of 8931 patients presenting for initial evaluation, 106 of 13,810 eyes had NV (prevalence = 0.77%, 95% confidence interval [CI], 0.60-0.90). Eighty-eight more eyes developed NV over 26,465 eye-years (incidence, 0.33%/eye-year; 95% CI, 0.27-0.41). Factors associated with incident NV include age <35 years compared with >35 years (adjusted hazard ratio [aHR], 2.4; 95% CI, 1.5-3.9), current cigarette smoking (aHR, 1.9; 95% CI, 1.1-3.4), and systemic lupus erythematosus (aHR, 3.5, 95% CI, 1.1-11). Recent diagnosis of uveitis was associated with an increased incidence of NV (compared with patients diagnosed >5 years ago, aHR, 2.4 [95% CI, 1.1-5.0] and aHR, 2.6 [95% CI, 1.2-6.0] for diagnosis within <1 year vs. 1-5 years, respectively). Compared with anterior uveitis, intermediate uveitis (aHR, 3.1; 95% CI, 1.5-6.6), posterior uveitis (aHR, 5.2; 95% CI, 2.5-11), and panuveitis (aHR, 4.3; 95% CI, 2.0-9.3) were associated with a similar degree of increased NV incidence. Active (aHR, 2.1, 95% CI, 1.2-3.7) and slightly active (aHR, 2.4, 95% CI, 1.3-4.4) inflammation were associated with an increased incidence of NV compared with inactive inflammation. Neovascularization incidence also was increased with retinal vascular occlusions (aHR, 10, 95% CI, 3.0-33), retinal vascular sheathing (aHR, 2.6, 95% CI, 1.4-4.9), and exudative retinal detachment (aHR, 4.1, 95% CI, 1.3-13). Diabetes mellitus was associated with a somewhat increased incidence of retinal NV (aHR, 2.3, 95% CI, 1.1-4.9), and systemic hypertension (aHR 1.5, 95% CI, 0.89-2.4) was associated with nonsignificantly increased NV incidence. Results were similar in sensitivity analyses excluding the small minority of patients with diabetes mellitus.ConclusionsRetinal NV is a rare complication of uveitis, which occurs more frequently in younger patients, smokers, and those with intermediate/posterior/panuveitis, systemic vasculopathy, retinal vascular disease, or active inflammation. Inflammation and retinal NV likely are linked; additional studies are needed to further elucidate this connection.

Project description:Equine recurrent uveitis (ERU) is a spontaneous, painful, and vision threatening disease affecting up to 25% of equine populations worldwide. Current treatments of ERU are non-specific and have many side effects which limits them to short-term use. In order to develop an effective therapy for ERU, we investigated the use of adeno-associated virus (AAV) gene therapy, exploiting a natural immune tolerance mechanism induced by equine interleukin-10 (Equine-IL10). The purpose of this study was to evaluate the therapeutic efficacy of a single intravitreal (IVT) dose of AAV8-Equine-IL10 gene therapy for inhibition of experimental autoimmune uveitis (EAU) in rats. Each rat was dosed intravitreally (IVT) in both eyes with either balanced salt solution (BSS) (control; n = 4), AAV8-Equine-IL10 at a low dose (2.4x109 vg; n = 5) or high dose (2.4x1010 vg; n = 5). EAU was induced in all groups of rats 7 days after IVT injections and euthanized 21 days post-injection. Ophthalmic examination and aqueous humor (AH) cell counts were recorded with the observer blinded to the treatment groups. Histopathology and qPCR were performed on selected ocular tissues. Data presented herein demonstrate that AAV8-Equine-IL10 treated rats exhibited a significant decrease in clinical inflammatory scores and AH cell counts compared to BSS-treated EAU eyes on days 10, 12 and 14 post EAU induction at both administered vector doses. Mean cellular histologic infiltrative scores were also significantly less in AAV8-Equine-IL10 dosed rats compared to the BSS group. Intravitreal injection of AAV8-Equine-IL10 resulted in Equine-IL10 cDNA expression in the ciliary body, retina, cornea, and optic nerve in a dose-dependent manner. A single IVT injection of AAV8-Equine-IL10 appeared to be well-tolerated and inhibited EAU even at the lowest administered dose. These results demonstrate safety and efficacy of AAV8-Equine-IL10 to prevent EAU and support continued exploration of AAV gene therapy for the treatment of equine and perhaps human recurrent uveitis.

Project description:Equine recurrent uveitis (ERU) is a common ocular disease of horses and described as a model for human autoimmune uveitis. This immune-mediated, inflammatory condition progressively destroys the eye, ultimately leading to blindness. Genetic and autoimmune factors, next to infections with Leptospira, are discussed as key factors in the pathogenesis. Furthermore, a release of neutrophil extracellular traps (NETs) by activated neutrophils is involved. NETs are composed of decondensed chromatin and proteins that can immobilize invading pathogens. However, if NETs accumulate, they can contribute to detrimental autoimmune processes. Thus, we aimed to investigate the impact of NETs in ERU patients. Therefore, we quantified several NET-markers (cell-free DNA, nucleosomes, citrullinated histone H3, histone-myeloperoxidase complexes, interleukin-17, equine cathelicidin 1 and DNase I activity) and NET-autoantibodies in sera and vitreous body fluids (VBF) of ERU-diseased horses and correlated the data with the disease status (signalment, ERU scores and Leptospira infection status). NET markers were detected to varying degrees in VBF of diseased horses, and partially correlated to disease severity and the presence of Leptospira spp. Cell-free DNA and nucleosomes as NET markers correlate with ERU severity in total and VBF scores, despite the presence of active DNases. Additionally, a significant correlation between fundus affection in the eye and NET autoantibodies was detectable. Therefore, we further investigated the influence of VBF samples from equine patients and isolated NETs on the blood-retina barrier in a cell culture model. VBF of diseased horses significantly induced cytotoxicity in retinal pigment epithelial cells. Moreover, partially digested NETs also resulted in cytotoxic effects. In the presence of lipopolysaccharide (LPS), the main component of the leptospiral surface, both undigested and completely digested NETs were cytotoxic. Correlations between the ERU-scores and Leptospira were also calculated. Detection of leptospiral DNA, and antibody titers of the serovar Grippotyphosa correlated with disease severity. In addition, a correlation between Leptospira and several NET markers was observed in VBF. Altogether, our findings suggest a positive correlation between NET markers with disease severity and involvement of Leptospira in the VBF of ERU-diseased horses, as well as a cytotoxic effect of NETs in eyes.

Dataset Information

Retinal glycoprotein enrichment by concanavalin a enabled identification of novel membrane autoantigen synaptotagmin-1 in equine recurrent uveitis.

Publications

Retinal glycoprotein enrichment by concanavalin a enabled identification of novel membrane autoantigen synaptotagmin-1 in equine recurrent uveitis.

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