Assessment and in vivo scoring of murine experimental autoimmune uveoretinitis using optical coherence tomography

Comprehensive Grading System for Experimental Autoimmune Uveitis in Mice

Experimental autoimmune uveitis (EAU) is the most commonly used animal model to study the progression of chronic uveitis and to test various therapies to treat the disease. However, to accurately evaluate the effectiveness of such treatments, a grading system that combines the latest imaging techniques with definitive quantitative grading thresholds is required. This study aimed to develop a comprehensive grading system that objectively evaluates EAU progression in C57BL/6J mice. EAU was induced following immunisation with interphotoreceptor retinoid-binding protein (IRBP) and pertussis toxin. Weekly fundus and optical coherence tomography (OCT) images were acquired over 12 weeks using a Micron IV imaging system. Each mouse was graded (between 0 to 4) based on changes seen on both the fundus (optic disc, retinal blood vessels and retinal tissue) and OCT (vitreous and retinal layers) images. A total EAU response (with a maximum score of 48) was calculated for each mouse based on the sum of the individual scores each week. Analysis of the clinical scores depicted a gradual increase in inflammatory signs including optic disc and vascular swelling, leukocyte infiltration in the vitreous, lesions in the retina and formation of granulomas and hyper-reflective foci in the retinal layers in EAU mice, with most signs reaching a plateau towards the end of the study period. Development of these signs into sight-threatening complications such as optic disc atrophy, structural damage to the retina and subretinal oedema were noted in 80-90% of mice suggesting consistent disease induction. Overall, a comprehensive and objective grading system encompassing all pathologies occurring in EAU mice was developed to enhance the preclinical evaluation of novel uveitis treatments.

Optimization of determinant factors associated with the efficiency of experimental autoimmune uveitis induction in C57BL/6 mice

Background

Experimental autoimmune uveitis (EAU) is a widely used animal model for uveitis research. The C57BL/6 mouse strain is the most commonly used mouse strain in the research of genetic modification, but C57BL/6 mice are not sufficiently susceptible to EAU induction, partly due to experimental factors. This work aims to optimize relevant factors to improve the efficiency of EAU induction in C57BL/6 mice.

Methods

To induce EAU, mice were immunized via intraperitoneal injection with pertussis (PTX) and subcutaneous injection with interphotoreceptor retinoid-binding protein peptide 1-20 (IRBP_1-20) emulsified with complete Freund's adjuvant (CFA). The severity of inflammation was assessed using several approaches. The relevant experimental factors were evaluated, including methods of emulsification and doses of peptide and PTX.

Results

Uveitis occurred at 8-12 days after immunization and reached its peak at 18-20 days, while T helper type 17 (Th17) cells peaked earlier at 14-18 days after immunization. Based on clinical and histological scores, 500 µg of IRBP peptide was the optimal dose required to induce EAU. The PTX dose demonstrated no influence on EAU incidence, but potentially affected the severity of uveitis. A single injection of 1,000 ng of PTX induced the most severe EAU and the highest proportion of Th17 cells. Compared to extruded emulsion, sonicated emulsion produced a higher incidence, higher histological score, and a 2-day-earlier onset of EAU. Electron microscopy showed a significantly different microstructure between the 2 emulsions.

Conclusions

This work optimized the protocols of EAU induction and obtained a high and stable induction rate with severe inflammation in the C57BL/6 mouse strain. Our results facilitate future experimental research involving uveitis.

Epigenetic drug screen identified IOX1 as an inhibitor of Th17-mediated inflammation through targeting TET2

BACKGROUND

Targeting helper T cells, especially Th17 cells, has become a plausible therapy for many autoimmune diseases.

METHODS

Using an in vitro culture system, we screened an epigenetics compound library for inhibitors of IFN-γ and IL-17 expression in murine Th1 and Th17 cultures.

FINDINGS

This identified IOX1 as an effective suppressor of IL-17 expression in both murine and human CD4⁺ T cells. Furthermore, we found that IOX1 suppresses Il17a expression directly by targeting TET2 activity on its promoter in Th17 cells. Using established pre-clinical models of intraocular inflammation, treatment with IOX1 in vivo reduced the migration/infiltration of Th17 cells into the site of inflammation and tissue damage.

INTERPRETATION

These results provide evidence of the strong potential for IOX1 as a viable therapy for inflammatory diseases, in particular of the eye.

FUNDING

This study was supported by the National Key Research and Development Program of China 2021YFA1101200 (2021YFA1101204) to LW and XW; the National Natural Science Foundation of China 81900844 to XH and 82171041 to LW; the China Postdoctoral Science Foundation 2021M700776 and the Scientific Research Project of Guangdong Provincial Bureau of Traditional Chinese Medicine 20221373 to YZ; and the National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS (National Health Service) Foundation Trust and University College London Institute of Ophthalmology, UK (DAC, LPS, PJPL, MS, ADD and RWJL). The views expressed are those of the authors and not necessarily those of the NIHR or the UK's Department of Health and Social Care.

Characterization and Validation of In Vitro and In Vivo Models to Investigate TNF-α-Induced Inflammation in Retinal Diseases

Purpose

Inflammation is implicated in the etiology of diverse retinopathies including uveitis, age-related macular degeneration or diabetic retinopathy. Tumor necrosis factor alpha (TNF-α) is a well-known proinflammatory cytokine that is described as a biomarker for inflammation in diverse retinopathies and therefore emerged as an interesting target to treat inflammation in the eye by neutralizing anti-TNF-α antibodies.

Methods

Recently, we have demonstrated that Adeno-associated virus (AAV)–mediated expression of human TNF-α in the murine eye induces retinal inflammation including vasculitis and fibrosis, thereby mimicking human disease-relevant pathologies. In a proof-of-mechanism study, we now tested whether AAV-TNF-α induced pathologies can be reversed by neutralizing TNF-α antibody treatment.

Results

Strikingly, a single intravitreal injection of the TNF-α antibody golimumab reduced AAV-TNF-α–induced retinal inflammation and retinal thickening. Furthermore, AAV-TNF-α–mediated impaired retinal function was partially rescued by golimumab as revealed by electroretinography recordings. Finally, to study TNF-α-induced vasculitis in human in vitro cell culture assays, we established a monocyte-to-endothelium adhesion co-culture system. Indeed, also in vitro TNF-α induced monocyte adhesion to human retinal endothelial cells, which was prevented by golimumab.

Conclusions

Overall, our study describes valuable in vitro and in vivo approaches to study the function of TNF-α in retinal inflammation and demonstrated a preclinical proof-of-mechanism treatment with golimumab.

Translational Relevance

The AAV-based model expressing human TNF-α allows us to investigate TNF-α–driven pathologies supporting research in mechanisms of retinal inflammation.

Analysis of Parainflammation in Chronic Glaucoma Using Vitreous-OCT Imaging

Glaucoma causes blindness due to the progressive death of retinal ganglion cells. The immune response chronically and subclinically mediates a homeostatic role. In current clinical practice, it is impossible to analyse neuroinflammation non-invasively. However, analysis of vitreous images using optical coherence tomography detects the immune response as hyperreflective opacities. This study monitors vitreous parainflammation in two animal models of glaucoma, comparing both healthy controls and sexes over six months. Computational analysis characterizes in vivo the hyperreflective opacities, identified histologically as hyalocyte-like Iba-1+ (microglial marker) cells. Glaucomatous eyes showed greater intensity and number of vitreous opacities as well as dynamic fluctuations in the percentage of activated cells (50–250 microns²) vs. non-activated cells (10–50 microns²), isolated cells (10 microns²) and complexes (>250 microns²). Smaller opacities (isolated cells) showed the highest mean intensity (intracellular machinery), were the most rounded at earlier stages (recruitment) and showed the greatest change in orientation (motility). Study of vitreous parainflammation could be a biomarker of glaucoma onset and progression.

Engineering adeno-associated viral vectors to evade innate immune and inflammatory responses

Nucleic acids are used in many therapeutic modalities, including gene therapy, but their ability to trigger host immune responses in vivo can lead to decreased safety and efficacy. In the case of adeno-associated viral (AAV) vectors, studies have shown that the genome of the vector activates Toll-like receptor 9 (TLR9), a pattern recognition receptor that senses foreign DNA. Here, we engineered AAV vectors to be intrinsically less immunogenic by incorporating short DNA oligonucleotides that antagonize TLR9 activation directly into the vector genome. The engineered vectors elicited markedly reduced innate immune and T cell responses and enhanced gene expression in clinically relevant mouse and pig models across different tissues, including liver, muscle, and retina. Subretinal administration of higher-dose AAV in pigs resulted in photoreceptor pathology with microglia and T cell infiltration. These adverse findings were avoided in the contralateral eyes of the same animals that were injected with the engineered vectors. However, intravitreal injection of higher-dose AAV in macaques, a more immunogenic route of administration, showed that the engineered vector delayed but did not prevent clinical uveitis, suggesting that other immune factors in addition to TLR9 may contribute to intraocular inflammation in this model. Our results demonstrate that linking specific immunomodulatory noncoding sequences to much longer therapeutic nucleic acids can "cloak" the vector from inducing unwanted immune responses in multiple, but not all, models. This "coupled immunomodulation" strategy may widen the therapeutic window for AAV therapies as well as other DNA-based gene transfer methods.

Quantitative Assessment of Experimental Ocular Inflammatory Disease

Ocular inflammation imposes a high medical burden on patients and substantial costs on the health-care systems that mange these often chronic and debilitating diseases. Many clinical phenotypes are recognized and classifying the severity of inflammation in an eye with uveitis is an ongoing challenge. With the widespread application of optical coherence tomography in the clinic has come the impetus for more robust methods to compare disease between different patients and different treatment centers. Models can recapitulate many of the features seen in the clinic, but until recently the quality of imaging available has lagged that applied in humans. In the model experimental autoimmune uveitis (EAU), we highlight three linked clinical states that produce retinal vulnerability to inflammation, all different from healthy tissue, but distinct from each other. Deploying longitudinal, multimodal imaging approaches can be coupled to analysis in the tissue of changes in architecture, cell content and function. This can enrich our understanding of pathology, increase the sensitivity with which the impacts of therapeutic interventions are assessed and address questions of tissue regeneration and repair. Modern image processing, including the application of artificial intelligence, in the context of such models of disease can lay a foundation for new approaches to monitoring tissue health.

Monitoring New Long-Lasting Intravitreal Formulation for Glaucoma with Vitreous Images Using Optical Coherence Tomography

Intravitreal injection is the gold standard therapeutic option for posterior segment pathologies, and long-lasting release is necessary to avoid reinjections. There is no effective intravitreal treatment for glaucoma or other optic neuropathies in daily practice, nor is there a non-invasive method to monitor drug levels in the vitreous. Here we show that a glaucoma treatment combining a hypotensive and neuroprotective intravitreal formulation (IF) of brimonidine–Laponite (BRI/LAP) can be monitored non-invasively using vitreoretinal interface imaging captured with optical coherence tomography (OCT) over 24 weeks of follow-up. Qualitative and quantitative characterisation was achieved by analysing the changes in vitreous (VIT) signal intensity, expressed as a ratio of retinal pigment epithelium (RPE) intensity. Vitreous hyperreflective aggregates mixed in the vitreous and tended to settle on the retinal surface. Relative intensity and aggregate size progressively decreased over 24 weeks in treated rat eyes as the BRI/LAP IF degraded. VIT/RPE relative intensity and total aggregate area correlated with brimonidine levels measured in the eye. The OCT-derived VIT/RPE relative intensity may be a useful and objective marker for non-invasive monitoring of BRI/LAP IF.

High-Resolution Imaging of Retinal Vasculitis by Flood Illumination Adaptive Optics Ophthalmoscopy: A Follow-up Study

Purpose: To monitor perivascular sheathing during the course of retinal vasculitis by flood illumination adaptive optics ophthalmoscopy (AOO). Methods: Perivenous sheathing and venous diameters were quantitatively analyzed by semi-automatic segmentation of AOO images in 12 eyes of treatment-naive patients with retinal vasculitis. Results: The width of venous sheathing ranged from 45 to 225 µm (mean 101.0 µm ± 54.3). In 10 cases, the underlying vein showed focal narrowing (mean ± SD 14% ± 10). Focal narrowing of arteries was also present in one eye. At presentation, width of sheathing and vessel diameters were not correlated with fluorescein leakage. During follow-up, 5 eyes showed an increase in vein diameter or resolution of narrowing and in 10 eyes a thinning of vascular sheathing was observed (p= .003). Conclusions: Perivenous sheathing may be quantitatively analyzed and monitored by AOO. AOO may therefore contribute to monitor vascular sheathing during posterior uveitis.

Effect of age and sex on neurodevelopment and neurodegeneration in the healthy eye: Longitudinal functional and structural study in the Long-Evans rat

The processes involved in neurodevelopment and aging have not yet been fully discovered. This is especially challenging in premorbid or borderline situations of neurodegenerative diseases such as Alzheimer's or glaucoma. The retina, as part of the central nervous system, can be considered the easiest and most accessible neural structure that can be analyzed using non-invasive methods. Animal studies of neuroretinal tissue in situations of health and under controlled conditions allow the earliest sex- and aging-induced changes to be analyzed so as to differentiate them from the first signs occurring in manifested disease. This study evaluates differences by age and sex based on intraocular pressure (IOP) and neuroretinal function and structure in healthy young and adult rats before decline due to senescence. For this purpose, eighty-five healthy Long-Evans rats (31 males and 54 females) were analyzed in this 6-month longitudinal study running from childhood to adulthood. IOP was measured by tonometer (Tonolab; Tiolat Oy Helsinki, Finland), neuroretinal function was recorded by flash scotopic and light-adapted photopic negative response electroretinography (ERG) (Roland consult® RETIanimal ERG, Germany) at 4, 16 and 28 weeks of age; and structure was evaluated by in vivo optical coherence tomography (OCT) (Spectralis, Heidelberg® Engineering, Germany). Analyzing both sexes together, IOP was below 20 mmHg throughout the study; retina (R), retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thicknesses measured by OCT decreased over time; an increase in ERG signal was recorded at week 16; and no differences were found between right and left eyes. However, analyzing differences by sex revealed that males had higher IOP (even reaching ocular hypertension [>20 mmHg] by the end of the study [7 months of age]), exhibited greater neuroretinal thickness but higher structural percentage loss, and had worse dark- and light-adapted function as measured by ERG than females. This study concludes that age and sex influenced neurodevelopment and neurodegeneration. Different structural and functional degenerative patterns were observed by sex; these occurred earlier and more intensely in males than in age-matched females.

A combination of inhibiting microglia activity and remodeling gut microenvironment suppresses the development and progression of experimental autoimmune uveitis

Noninfectious (autoimmune and immune-mediated) uveitis is an ocular inflammatory disease which can lead to blindness in severe cases. Due to the potential side effects of first-line drugs for clinical uveitis, novel drugs and targets against uveitis are still urgently needed. In the present study, using rat experimental autoimmune uveitis (EAU) model, we first found that minocycline treatment can substantially inhibit the development of EAU and improve the retinal function by suppressing the retinal microglial activation, and block the infiltration of inflammatory cells, including Th17, into the retina by decreasing the major histocompatibility complex class II (MHC II) expression in resident and infiltrating cells. Moreover, we demonstrated that minocycline treatment can remodel the gut microenvironment of EAU rats by restoring the relative abundance of Ruminococcus bromii, Streptococcus hyointestinalis, and Desulfovibrio sp. ABHU2SB and promoting a functional shift in the gut via reversing the levels of L-proline, allicin, aceturic acid, xanthine, and leukotriene B4, and especially increasing the production of propionic acid, histamine, and pantothenic acid. At last, we revealed that minocycline treatment can significantly attenuate the progression of EAU after inflammation onset, which may be explained by the role of minocycline in the remodeling of the gut microenvironment since selective elimination of retinal microglia on the later stages of EAU was shown to have little effect. These data clearly demonstrated that inhibition of microglial activation and remodeling of the gut microenvironment can suppress the development and progression of experimental autoimmune uveitis. Considering the excellent safety profile of minocycline in multiple clinical experiments, we suggest that minocycline may have therapeutic implications for clinical uveitis.

Gene Therapy for Glaucoma by Ciliary Body Aquaporin 1 Disruption Using CRISPR-Cas9

Glaucoma is a common cause of blindness, yet current therapeutic options are imperfect. Clinical trials have invariably shown that reduction in intraocular pressure (IOP) regardless of disease subtype prevents visual loss. Reducing ciliary body aqueous humor production can lower IOP, and the adeno-associated virus ShH10 serotype was identified as able to transduce mouse ciliary body epithelium following intravitreal injection. Using ShH10 to deliver a single vector CRISPR-Cas9 system disrupting Aquaporin 1 resulted in reduced IOP in treated eyes (10.4 ± 2.4 mmHg) compared with control (13.2 ± 2.0 mmHg) or non-injected eyes (13.1 ± 2.8 mmHg; p < 0.001; n = 12). Editing in the aquaporin 1 gene could be detected in ciliary body, and no off-target increases in corneal or retinal thickness were identified. In experimental mouse models of corticosteroid and microbead-induced ocular hypertension, IOP could be reduced to prevent ganglion cell loss (32 ± 4 /mm²) compared with untreated eyes (25 ± 5/mm²; p < 0.01). ShH10 could transduce human ciliary body from post-mortem donor eyes in ex vivo culture with indel formation detectable in the Aquaporin 1 locus. Clinical translation of this approach to patients with glaucoma may permit long-term reduction of IOP following a single injection.

AAV Mediated Delivery of Myxoma Virus M013 Gene Protects the Retina against Autoimmune Uveitis

Uveoretinitis is an ocular autoimmune disease caused by the activation of autoreactive T- cells targeting retinal antigens. The myxoma M013 gene is known to block NF-κB (Nuclear Factor kappa-light-chain-enhancer of activated B cells) and inflammasome activation, and its gene delivery has been demonstrated to protect the retina against lipopolysaccharide (LPS)-induced uveitis. In this report we tested the efficacy of M013 in an experimental autoimmune uveoretinitis (EAU) mouse model. B10RIII mice were injected intravitreally with AAV (adeno associated virus) vectors delivering either secreted GFP (sGFP) or sGFP-TatM013. Mice were immunized with interphotorecptor retinoid binding protein residues 161–180 (IRBP_161–180) peptide in complete Freund’s adjuvant a month later. Mice were evaluated by fundoscopy and spectral domain optical coherence tomography (SD-OCT) at 14 days post immunization. Eyes were evaluated by histology and retina gene expression changes were measured by reverse transcribed quantitative PCR (RT-qPCR). No significant difference in ERG or retina layer thickness was observed between sGFP and sGFP-TatM013 treated non-uveitic mice, indicating safety of the vector. In EAU mice, expression of sGFP-TatM013 strongly lowered the clinical score and number of infiltrative cells within the vitreous humor when compared to sGFP treated eyes. Retina structure was protected, and pro-inflammatory genes expression was significantly decreased. These results indicate that gene delivery of myxoma M013 could be of clinical benefit against autoimmune diseases.

Retinal microglia initiate neuroinflammation in ocular autoimmunity

Autoimmune uveitis is a sight-threatening ocular inflammatory condition in which the retina and uveal tissues become a target of autoreactive immune cells. While microglia have been studied extensively in autoimmune uveitis, their exact function remains uncertain. The objective of the current study was to determine whether resident microglia are necessary and sufficient to initiate and amplify retinal inflammation in autoimmune uveitis. In this study, we clearly demonstrate that microglia are essential for initiating infiltration of immune cells utilizing a murine model of experimental autoimmune uveoretinitis (EAU) and the recently identified microglia-specific marker P2ry12. Initiating disease is the primary function of microglia in EAU, since eliminating microglia during the later stages of EAU had little effect, indicating that the function of circulating leukocytes is to amplify and sustain destructive inflammation once microglia have triggered disease. In the absence of microglia, uveitis does not develop, since leukocytes cannot gain entry through the blood-retinal barrier, illustrating that microglia play a critical role in regulating infiltration of inflammatory cells into the retina.

Behavior of hyperreflective foci in non-infectious uveitic macular edema, a 12-month follow-up prospective study

Background

Hyperreflective foci have been described in OCT imaging of patients with retinal vascular diseases. It has been suggested that they may play a role as a prognostic factor of visual outcomes in these diseases. The purpose of this study is to describe the presence of hyperreflective foci in patients with non-infectious uveitic macular edema and evaluate their behavior after treatment.

Methods

We conducted a multicenter, prospective, observational, 12-month follow-up study. Inclusion criteria were age > 18 years and a diagnosis of non-infectious uveitic macular edema, defined as central macular thickness of > 300 μm as measured by OCT and fluid in the macula. Collected data included best corrected visual acuity, central macular thickness and the presence, number and distribution (inner or outer retinal layers) of hyperreflective foci. Evaluations were performed at baseline, and at 1, 3, 6, and 12 months after starting treatment.

Results

We included 24 eyes of 24 patients. The frequency of patients with ≥11 hyperreflective foci was 58.4% at baseline, falling to 20.8% at 12 months. Further, hyperreflective foci were observed in the outer retinal layers in 50% of patients at baseline and just 28.6% at 12 months. Mean LogMAR visual acuity improved from 0.55 (95% CI 0.4–0.71) at baseline to 0.22 (95% CI 0.08–0.35) at 12 months (p < 0.001). Mean central macular thickness decreased from 453.83 μm (95% CI 396.6–511) at baseline to 269.32 μm (95% CI 227.7–310.9) at 12 months (P < 0.001). Central macular thickness was associated with number (p = 0.017) and distribution (p = 0.004) of hyperreflective foci.

Conclusions

We have observed hyperreflective foci in most of our patients with non-infectious uveitic macular edema. During follow-up and after treatment, the number of foci diminished and they tended to be located in the inner layers of the retina.

Re-programming immunosurveillance in persistent non-infectious ocular inflammation

Ocular function depends on a high level of anatomical integrity. This is threatened by inflammation, which alters the local tissue over short and long time-scales. Uveitis due to autoimmune disease, especially when it involves the retina, leads to persistent changes in how the eye interacts with the immune system. The normal pattern of immune surveillance, which for immune privileged tissues is limited, is re-programmed. Many cell types, that are not usually present in the eye, become detectable. There are changes in the tissue homeostasis and integrity. In both human disease and mouse models, in the most extreme cases, immunopathological findings consistent with development of ectopic lymphoid-like structures and disrupted angiogenesis accompany severely impaired eye function. Understanding how the ocular environment is shaped by persistent inflammation is crucial to developing novel approaches to treatment.

In Vivo Bioluminescence Imaging for Longitudinal Monitoring of Inflammation in Animal Models of Uveitis

Purpose

We develop a quantitative bioluminescence assay for in vivo longitudinal monitoring of inflammation in animal models of uveitis.

Methods

Three models of experimental uveitis were induced in C57BL/6 albino mice: primed mycobacterial uveitis (PMU), endotoxin-induced uveitis (EIU), and experimental autoimmune uveitis (EAU). Intraperitoneal injection of luminol sodium salt, which emits light when oxidized, provided the bioluminescence substrate. Bioluminescence images were captured by a PerkinElmer In Vivo Imaging System (IVIS) Spectrum and total bioluminescence was analyzed using Living Image software. Bioluminescence on day zero was compared to bioluminescence on the day of peak inflammation for each model. Longitudinal bioluminescence imaging was performed in EIU and EAU.

Results

In the presence of luminol, intraocular inflammation generates detectable bioluminescence in three mouse models of uveitis. Peak bioluminescence in inflamed PMU eyes (1.46 × 10⁵ photons/second [p/s]) was significantly increased over baseline (1.47 × 10⁴ p/s, P = 0.01). Peak bioluminescence in inflamed EIU eyes (3.18 × 10⁴ p/s) also was significantly increased over baseline (1.09 × 10⁴ p/s, P = 0.04), and returned to near baseline levels by 48 hours. In EAU, there was a nonsignificant increase in bioluminescence at peak inflammation.

Conclusions

In vivo bioluminescence may be used as a noninvasive, quantitative measure of intraocular inflammation in animal models of uveitis. Primed mycobacterial uveitis and EIU are both acute models with robust anterior inflammation and demonstrated significant changes in bioluminescence corresponding with peak inflammation. Experimental autoimmune uveitis is a more indolent posterior uveitis and generated a more modest bioluminescent signal. In vivo imaging system bioluminescence is a nonlethal, quantifiable assay that can be used for monitoring inflammation in animal models of uveitis.

Quantitative Assessment of Anterior Segment Inflammation in a Rat Model of Uveitis Using Spectral-Domain Optical Coherence Tomography

Purpose

To develop anterior segment spectral-domain optical coherence tomography (SD-OCT) and quantitative image analysis for use in experimental uveitis in rats.

Methods

Acute anterior uveitis was generated in Lewis rats. A spectral domain anterior segment OCT system was used to image the anterior chamber (AC) and ciliary body at baseline and during peak inflammation 2 days later. Customized MatLab image analysis algorithms were developed to segment the AC, count AC cells, calculate central corneal thickness (CCT), segment the ciliary body and zonules, and quantify the level of ciliary body inflammation with the ciliary body index (CBI). Images obtained at baseline and during peak inflammation were compared. Finally, longitudinal imaging and image analysis was performed over the 2-week course of inflammation.

Results

Spectral-domain optical coherence tomography identifies structural features of inflammation. Anterior chamber cell counts at peak inflammation obtained by automated image analysis and human grading were highly correlated (r = 0.961), and correlated well with the histologic score of inflammation (r = 0.895). Inflamed eyes showed a significant increase in average CCT (27 μm, P = 0.02) and an increase in average CBI (P < 0.0001). Longitudinal imaging and quantitative image analysis identified a significant change in AC cell and CBI on day 2 with spontaneous resolution of inflammation by day 14.

Conclusions

Spectral-domain optical coherence tomography provides high-resolution images of the structural changes associated with anterior uveitis in rats. Anterior chamber cell count and CBI determined by semi-automated image analysis strongly correlates with inflammation, and can be used to quantify inflammation longitudinally in single animals.

Longitudinal Intravital Imaging of the Retina Reveals Long-term Dynamics of Immune Infiltration and Its Effects on the Glial Network in Experimental Autoimmune Uveoretinitis, without Evident Signs of Neuronal Dysfunction in the Ganglion Cell Layer

A hallmark of autoimmune retinal inflammation is the infiltration of the retina with cells of the innate and adaptive immune system, leading to detachment of the retinal layers and even to complete loss of the retinal photoreceptor layer. As the only optical system in the organism, the eye enables non-invasive longitudinal imaging studies of these local autoimmune processes and of their effects on the target tissue. Moreover, as a window to the central nervous system (CNS), the eye also reflects general neuroinflammatory processes taking place at various sites within the CNS. Histological studies in murine neuroinflammatory models, such as experimental autoimmune uveoretinitis (EAU) and experimental autoimmune encephalomyelitis, indicate that immune infiltration is initialized by effector CD4⁺ T cells, with the innate compartment (neutrophils, macrophages, and monocytes) contributing crucially to tissue degeneration that occurs at later phases of the disease. However, how the immune attack is orchestrated by various immune cell subsets in the retina and how the latter interact with the target tissue under in vivo conditions is still poorly understood. Our study addresses this gap with a novel approach for intravital two-photon microscopy, which enabled us to repeatedly track CD4⁺ T cells and LysM phagocytes during the entire course of EAU and to identify a specific radial infiltration pattern of these cells within the inflamed retina, starting from the optic nerve head. In contrast, highly motile CX3CR1+ cells display an opposite radial motility pattern, toward the optic nerve head. These inflammatory processes induce modifications of the microglial network toward an activated morphology, especially around the optic nerve head and main retinal blood vessels, but do not affect the neurons within the ganglion cell layer. Thanks to the new technology, non-invasive correlation of clinical scores of CNS-related pathologies with immune infiltrate behavior and subsequent tissue dysfunction is now possible. Hence, the new approach paves the way for deeper insights into the pathology of neuroinflammatory processes on a cellular basis, over the entire disease course.

MMP-3 Deficiency Alleviates Endotoxin-Induced Acute Inflammation in the Posterior Eye Segment

Matrix metalloproteinase-3 (MMP-3) is known to mediate neuroinflammatory processes by activating microglia, disrupting blood-central nervous system barriers and supporting neutrophil influx into the brain. In addition, the posterior part of the eye, more specifically the retina, the retinal pigment epithelium (RPE) and the blood-retinal barrier, is affected upon neuroinflammation, but a role for MMP-3 during ocular inflammation remains elusive. We investigated whether MMP-3 contributes to acute inflammation in the eye using the endotoxin-induced uveitis (EIU) model. Systemic administration of lipopolysaccharide induced an increase in MMP-3 mRNA and protein expression level in the posterior part of the eye. MMP-3 deficiency or knockdown suppressed retinal leukocyte adhesion and leukocyte infiltration into the vitreous cavity in mice subjected to EIU. Moreover, retinal and RPE mRNA levels of intercellular adhesion molecule 1 (Icam1), interleukin 6 (Il6), cytokine-inducible nitrogen oxide synthase (Nos2) and tumor necrosis factor α (Tnfα), which are key molecules involved in EIU, were clearly reduced in MMP-3 deficient mice. In addition, loss of MMP-3 repressed the upregulation of the chemokines monocyte chemoattractant protein (MCP)-1 and (C-X-C motif) ligand 1 (CXCL1). These findings suggest a contribution of MMP-3 during EIU, and its potential use as a therapeutic drug target in reducing ocular inflammation.

Doyne lecture 2016: intraocular health and the many faces of inflammation

Dogma for reasons of immune privilege including sequestration (sic) of ocular antigen, lack of lymphatic and immune competent cells in the vital tissues of the eye has long evaporated. Maintaining tissue and cellular health to preserve vision requires active immune responses to prevent damage and respond to danger. A priori the eye must contain immune competent cells, undergo immune surveillance to ensure homoeostasis as well as an ability to promote inflammation. By interrogating immune responses in non-infectious uveitis and compare with age-related macular degeneration (AMD), new concepts of intraocular immune health emerge. The role of macrophage polarisation in the two disorders is a tractable start. TNF-alpha regulation of macrophage responses in uveitis has a pivotal role, supported via experimental evidence and validated by recent trial data. Contrast this with the slow, insidious degeneration in atrophic AMD or in neovasular AMD, with the compelling genetic association with innate immunity and complement, highlights an ability to attenuate pathogenic immune responses and despite known inflammasome activation. Yolk sac-derived microglia maintains tissue immune health. The result of immune cell activation is environmentally dependent, for example, on retinal cell bioenergetics status, autophagy and oxidative stress, and alterations that skew interaction between macrophages and retinal pigment epithelium (RPE). For example, dead RPE eliciting macrophage VEGF secretion but exogenous IL-4 liberates an anti-angiogenic macrophage sFLT-1 response. Impaired autophagy or oxidative stress drives inflammasome activation, increases cytotoxicity, and accentuation of neovascular responses, yet exogenous inflammasome-derived cytokines, such as IL-18 and IL-33, attenuate responses.

Flow cytometric analysis of inflammatory and resident myeloid populations in mouse ocular inflammatory models

Myeloid cells make a pivotal contribution to tissue homeostasis during inflammation. Both tissue-specific resident populations and infiltrating myeloid cells can cause tissue injury through aberrant activation and/or dysregulated activity. Reliable identification and quantification of myeloid cells within diseased tissues is important to understand pathological inflammatory processes. Flow cytometry is a valuable technique for leukocyte analysis, but a standardized flow cytometric method for myeloid cell populations in the eye is lacking. Here, we validate a reproducible flow cytometry gating approach to characterize myeloid cells in several commonly used models of ocular inflammation. We profile and quantify myeloid subsets across these models, and highlight the value of this strategy in identifying phenotypic differences using Ccr2-deficient mice. This method will aid standardization in the field and facilitate future investigations into the roles of myeloid cells during ocular inflammation.

Primed Mycobacterial Uveitis (PMU): Histologic and Cytokine Characterization of a Model of Uveitis in Rats

PURPOSE

The purpose of this study was to compare the histologic features and cytokine profiles of experimental autoimmune uveitis (EAU) and a primed mycobacterial uveitis (PMU) model in rats.

METHODS

In Lewis rats, EAU was induced by immunization with interphotoreceptor binding protein peptide, and PMU was induced by immunization with a killed mycobacterial extract followed by intravitreal injection of the same extract. Clinical course, histology, and the cytokine profiles of the aqueous and vitreous were compared using multiplex bead fluorescence immunoassays.

RESULTS

Primed mycobacterial uveitis generates inflammation 2 days after intravitreal injection and resolves spontaneously 14 days later. CD68+ lymphocytes are the predominant infiltrating cells and are found in the anterior chamber, surrounding the ciliary body and in the vitreous. In contrast to EAU, no choroidal infiltration or retinal destruction is noted. At the day of peak inflammation, C-X-C motif ligand 10 (CXCL10), IL-1β, IL-18, and leptin were induced in the aqueous of both models. Interleukin-6 was induced 2-fold in the aqueous of PMU but not EAU. Cytokines elevated in the aqueous of EAU exclusively include regulated on activation, normal T cell expressed and secreted (RANTES), lipopolysaccharide-induced CXC chemokine (LIX), growth-related oncogene/keratinocyte chemokine (GRO/KC), VEGF, monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1α (MIP-1α), and IL-17A. In the vitreous, CXCL10, GRO/KC, RANTES, and MIP-1α were elevated in both models. Interleukin-17A and IL-18 were elevated exclusively in EAU.

CONCLUSIONS

Primed mycobacterial uveitis generates an acute anterior and intermediate uveitis without retinal involvement. Primed mycobacterial uveitis has a distinct proinflammatory cytokine profile compared with EAU, suggesting PMU is a good complementary model for study of immune-mediated uveitis. CXCL10, a proinflammatory cytokine, was increased in the aqueous and vitreous of both models and may be a viable therapeutic target.

Multimodal analysis of ocular inflammation using the endotoxin-induced uveitis mouse model

Endotoxin-induced uveitis (EIU) in rodents is a model of acute Toll-like receptor 4 (TLR4)-mediated organ inflammation, and has been used to model human anterior uveitis, examine leukocyte trafficking and test novel anti-inflammatory therapeutics. Wider adoption has been limited by the requirement for manual, non-specific, cell-count scoring of histological sections from each eye as a measure of disease severity. Here, we describe a comprehensive and efficient technique that uses ocular dissection and multimodal tissue analysis. This allows matched disease scoring by multicolour flow cytometric analysis of the inflammatory infiltrate, protein analysis on ocular supernatants and qPCR on remnant tissues of the same eye. Dynamic changes in cell populations could be identified and mapped to chemokine and cytokine changes over the course of the model. To validate the technique, dose-responsive suppression of leukocyte infiltration by recombinant interleukin-10 was demonstrated, as well as selective suppression of the monocyte (CD11b+Ly6C+) infiltrate, in mice deficient for eitherCcl2orCcr2 Optical coherence tomography (OCT) was used for the first time in this model to allowin vivoimaging of infiltrating vitreous cells, and correlated with CD11b+Ly6G+ counts to provide another unique measure of cell populations in the ocular tissue. Multimodal tissue analysis of EIU is proposed as a new standard to improve and broaden the application of this model.

A chimeric Cfh transgene leads to increased retinal oxidative stress, inflammation, and accumulation of activated subretinal microglia in mice

PURPOSE

Variants of complement factor H (Cfh) affecting short consensus repeats (SCRs) 6 to 8 increase the risk of age-related macular degeneration. Our aim was to explore the effect of expressing a Cfh variant on the in vivo susceptibility of the retina and RPE to oxidative stress and inflammation, using chimeric Cfh transgenic mice (chCfhTg).

METHODS

The chCfhTg and age-matched C57BL/6J (B6) mice were subjected to oxidative stress by either normal aging, or by exposure to a combination of oral hydroquinone (0.8% HQ) and increased light. Eyes were collected for immunohistochemistry of RPE-choroid flat mounts and of retinal sections, ELISA, electron microscopy, and RPE/microglia gene expression analysis.

RESULTS

Aging mice to 2 years led to an increased accumulation of basal laminar deposits, subretinal microglia/macrophages (MG/MΦ) staining for CD16 and for malondialdehyde (MDA), and MDA-modified proteins in the retina in chCfhTg compared to B6 mice. The chCfhTg mice maintained on HQ diet and increased light showed greater deposition of basal laminar deposits, more accumulation of fundus spots suggestive of MG/MΦ, and increased deposition of C3d in the sub-RPE space, compared to controls. In addition, chCfhTg mice demonstrated upregulation of NLRP3, IP-10, CD68, and TREM-2 in the RNA isolates from RPE/MG/MΦ.

CONCLUSIONS

Expression of a Cfh transgene introducing a variant in SCRs 6 to 8 was sufficient to lead to increased retinal/RPE susceptibility to oxidative stress, a proinflammatory MG/MΦ phenotype, and a proinflammatory RPE/MG/MΦ gene expression profile in a transgenic mouse model. Our data suggest that altered interactions of Cfh with MDA-modified proteins may be relevant in explaining the effects of the Cfh variant.

A simple method for in vivo labelling of infiltrating leukocytes in the mouse retina using indocyanine green dye

We have developed a method to label and image myeloid cells infiltrating the mouse retina and choroid in vivo, using a single depot injection of indocyanine green dye (ICG). This was demonstrated using the following ocular models of inflammation and angiogenesis: endotoxin-induced uveitis, experimental autoimmune uveoretinitis and laser-induced choroidal neovascularization model. A near-infrared scanning ophthalmoscope was used for in vivo imaging of the eye, and flow cytometry was used on blood and spleen to assess the number and phenotype of labelled cells. ICG was administered 72 h before the induction of inflammation to ensure clearance from the systemic circulation. We found that in vivo intravenous administration failed to label any leukocytes, whereas depot injection, either intraperitoneal or subcutaneous, was successful in labelling leukocytes infiltrating into the retina. Progression of inflammation in the retina could be traced over a period of 14 days following a single depot injection of ICG. Additionally, bright-field microscopy, spectrophotometry and flow cytometric analysis suggest that the predominant population of cells stained by ICG are circulating myeloid cells. The translation of this approach into clinical practice would enable visualization of immune cells in situ. This will not only provide a greater understanding of pathogenesis, monitoring and assessment of therapy in many human ocular diseases but might also open the ability to image immunity live for neurodegenerative disorders, cardiovascular disease and systemic immune-mediated disorders.

Summary: We show here that peripheral leukocytes can be labelled with ICG in vivo and then directly imaged as they invade the retina after inflammatory stimuli.

Dual Function of the IRF8 Transcription Factor in Autoimmune Uveitis: Loss of IRF8 in T Cells Exacerbates Uveitis, Whereas Irf8 Deletion in the Retina Confers Protection

IFN regulatory factor 8 (IRF8) is constitutively expressed in monocytes and B cells and plays a critical role in the functional maturation of microglia cells. It is induced in T cells following Ag stimulation, but its functions are less well understood. However, recent studies in mice with T cell-specific Irf8 disruption under direction of the Lck promoter (LCK-IRF8KO) suggest that IRF8 directs a silencing program for Th17 differentiation, and IL-17 production is markedly increased in IRF8-deficient T cells. Paradoxically, loss of IRF8 in T cells has no effect on the development or severity of experimental autoimmune encephalomyelitis (EAE), although exacerbating colitis in a mouse colitis model. In contrast, mice with a macrophage/microglia-specific Irf8 disruption are resistant to EAE, further confounding our understanding of the roles of IRF8 in host immunity and autoimmunity. To clarify the role of IRF8 in autoimmune diseases, we have generated two mouse strains with targeted deletion of Irf8 in retinal cells, including microglial cells and a third mouse strain with targeted Irf8 deletion in T cells under direction of the nonpromiscuous, CD4 promoter (CD4-IRF8KO). In contrast to the report that IRF8 deletion in T cells has no effect on EAE, experimental autoimmune uveitis is exacerbated in CD4-IRF8KO mice and disease enhancement correlates with significant expansion of Th17 cells and a reduction in T regulatory cells. In contrast to CD4-IRF8KO mice, Irf8 deletion in retinal cells confers protection from uveitis, underscoring divergent and tissue-specific roles of IRF8 in host immunity. These results raise a cautionary note in the context of therapeutic targeting of IRF8.

In vivo multi-modal imaging of experimental autoimmune uveoretinitis in transgenic reporter mice reveals the dynamic nature of inflammatory changes during disease progression

Background

Experimental autoimmune uveoretinitis (EAU) is a widely used experimental animal model of human endogenous posterior uveoretinitis. In the present study, we performed in vivo imaging of the retina in transgenic reporter mice to investigate dynamic changes in exogenous inflammatory cells and endogenous immune cells during the disease process.

Methods

Transgenic mice (C57Bl/6 J Cx₃cr1^GFP/+, C57Bl/6 N CD11c-eYFP, and C57Bl/6 J LysM-eGFP) were used to visualize the dynamic changes of myeloid-derived cells, putative dendritic cells and neutrophils during EAU. Transgenic mice were monitored with multi-modal fundus imaging camera over five time points following disease induction with the retinal auto-antigen, interphotoreceptor retinoid binding protein (IRBP_1–20). Disease severity was quantified with both clinical and histopathological grading.

Results

In the normal C57Bl/6 J Cx₃cr1^GFP/+ mouse Cx₃cr1-expressing microglia were evenly distributed in the retina. In C57Bl/6 N CD11c-eYFP mice clusters of CD11c-expressing cells were noted in the retina and in C57Bl/6 J LysM-eGFP mice very low numbers of LysM-expressing neutrophils were observed in the fundus. Following immunization with IRBP_1–20, fundus examination revealed accumulations of Cx₃cr1-GFP⁺ myeloid cells, CD11c-eYFP⁺ cells and LysM-eGFP⁺ myelomonocytic cells around the optic nerve head and along retinal vessels as early as day 14 post-immunization. CD11c-eYFP⁺ cells appear to resolve marginally earlier (day 21 post-immunization) than Cx₃cr1-GFP⁺ and LysM-eGFP⁺ cells. The clinical grading of EAU in transgenic mice correlated closely with histopathological grading.

Conclusions

These results illustrate that in vivo fundus imaging of transgenic reporter mice allows direct visualization of various exogenously and endogenously derived leukocyte types during EAU progression. This approach acts as a valuable adjunct to other methods of studying the clinical course of EAU.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0235-6) contains supplementary material, which is available to authorized users.

Gene therapy restores vision in rd1 mice after removal of a confounding mutation in Gpr179

The rd1 mouse with a mutation in the Pde6b gene was the first strain of mice identified with a retinal degeneration. However, AAV-mediated gene supplementation of rd1 mice only results in structural preservation of photoreceptors, and restoration of the photoreceptor-mediated a-wave, but not in restoration of the bipolar cell-mediated b-wave. Here we show that a mutation in Gpr179 prevents the full restoration of vision in rd1 mice. Backcrossing rd1 with C57BL6 mice reveals the complete lack of b-wave in a subset of mice, consistent with an autosomal recessive Mendelian inheritance pattern. We identify a mutation in the Gpr179 gene, which encodes for a G-protein coupled receptor localized to the dendrites of ON-bipolar cells. Gene replacement in rd1 mice that are devoid of the mutation in Gpr179 successfully restores the function of both photoreceptors and bipolar cells, which is maintained for up to 13 months. Our discovery may explain the failure of previous gene therapy attempts in rd1 mice, and we propose that Grp179 mutation status should be taken into account in future studies involving rd1 mice.

Optical coherence tomography based microangiography for quantitative monitoring of structural and vascular changes in a rat model of acute uveitis in vivo: a preliminary study

Uveitis models in rodents are important in the investigation of pathogenesis in human uveitis and the development of appropriate therapeutic strategies for treatment. Quantitative monitoring of ocular inflammation in small animal models provides an objective metric to assess uveitis progression and/or therapeutic effects. We present a new application of optical coherence tomography (OCT) and OCT-based microangiography (OMAG) to a rat model of acute anterior uveitis induced by intravitreal injection of a killed mycobacterial extract. OCT/OMAG is used to provide noninvasive three-dimensional imaging of the anterior segment of the eyes prior to injection (baseline) and two days post-injection (peak inflammation) in rats with and without steroid treatments. OCT imaging identifies characteristic structural and vascular changes in the anterior segment of the inflamed animals when compared to baseline images. Characteristics of inflammation identified include anterior chamber cells, corneal edema, pupillary membranes, and iris vasodilation. In contrast, no significant difference from the control is observed for the steroid-treated eye. These findings are compared with the histology assessment of the same eyes. In addition, quantitative measurements of central corneal thickness and iris vessel diameter are determined. This pilot study demonstrates that OCT-based microangiography promises to be a useful tool for the assessment and management of uveitis in vivo.

Retinal microglia: just bystander or target for therapy?

Resident microglial cells can be regarded as the immunological watchdogs of the brain and the retina. They are active sensors of their neuronal microenvironment and rapidly respond to various insults with a morphological and functional transformation into reactive phagocytes. There is strong evidence from animal models and in situ analyses of human tissue that microglial reactivity is a common hallmark of various retinal degenerative and inflammatory diseases. These include rare hereditary retinopathies such as retinitis pigmentosa and X-linked juvenile retinoschisis but also comprise more common multifactorial retinal diseases such as age-related macular degeneration, diabetic retinopathy, glaucoma, and uveitis as well as neurological disorders with ocular manifestation. In this review, we describe how microglial function is kept in balance under normal conditions by cross-talk with other retinal cells and summarize how microglia respond to different forms of retinal injury. In addition, we present the concept that microglia play a key role in local regulation of complement in the retina and specify aspects of microglial aging relevant for chronic inflammatory processes in the retina. We conclude that this resident immune cell of the retina cannot be simply regarded as bystander of disease but may instead be a potential therapeutic target to be modulated in the treatment of degenerative and inflammatory diseases of the retina.

Autoimmune and autoinflammatory mechanisms in uveitis

The eye, as currently viewed, is neither immunologically ignorant nor sequestered from the systemic environment. The eye utilises distinct immunoregulatory mechanisms to preserve tissue and cellular function in the face of immune-mediated insult; clinically, inflammation following such an insult is termed uveitis. The intra-ocular inflammation in uveitis may be clinically obvious as a result of infection (e.g. toxoplasma, herpes), but in the main infection, if any, remains covert. We now recognise that healthy tissues including the retina have regulatory mechanisms imparted by control of myeloid cells through receptors (e.g. CD200R) and soluble inhibitory factors (e.g. alpha-MSH), regulation of the blood retinal barrier, and active immune surveillance. Once homoeostasis has been disrupted and inflammation ensues, the mechanisms to regulate inflammation, including T cell apoptosis, generation of T_reg cells, and myeloid cell suppression in situ, are less successful. Why inflammation becomes persistent remains unknown, but extrapolating from animal models, possibilities include differential trafficking of T cells from the retina, residency of CD8⁺ T cells, and alterations of myeloid cell phenotype and function. Translating lessons learned from animal models to humans has been helped by system biology approaches and informatics, which suggest that diseased animals and people share similar changes in T cell phenotypes and monocyte function to date. Together the data infer a possible cryptic infectious drive in uveitis that unlocks and drives persistent autoimmune responses, or promotes further innate immune responses. Thus there may be many mechanisms in common with those observed in autoinflammatory disorders.

Evaluation of mouse experimental autoimmune uveoretinitis by spectral domain optical coherence tomography

AIMS

To evaluate the efficacy of spectral domain optical coherence tomography (SD-OCT) in monitoring the development of mouse experimental autoimmune uveoretinitis (EAU) as an animal model of endogenous uveitis, and to develop an OCT-based grading system for EAU severity.

METHODS

C57BL/6 mice were immunised with human interphotoreceptor retinoid-binding protein (amino acid sequence 1-20) peptide and complete Freund's adjuvant to induce EAU. The development of EAU was monitored by SD-OCT serially throughout the disease course, and the images were graded from 1 to 4 and compared with the clinical and histopathological grades.

RESULTS

SD-OCT images depicted retinal lamella structures including the inner segment/outer segment (IS/OS) line in normal mice. Retinal structural changes were observed on SD-OCT images in mice that developed EAU clinically scored as grade 1 or higher, which precisely corresponded to the pathological findings. The SD-OCT images of EAU were graded as follows: grade 1, a few infiltrating cells in the vitreous and retina; grade 2, increased vitreous cells, retinal vasculitis, and granulomatous lesion; grade 3, cell infiltration into the whole retina, disappearance of IS/OS line, and destruction of the retinal layer structure; and grade 4, disappearance of the outer retina. The SD-OCT grade of EAU based on these criteria correlated significantly with both the clinical grade (R(2)=0.282, p<0.005) and histopathological grade (R(2)=0.846, p<0.0001).

CONCLUSIONS

SD-OCT is useful for evaluating the development and severity of mouse EAU. The SD-OCT scoring system we developed accurately reflects clinical and histopathological changes.

SOCS3 deletion in T lymphocytes suppresses development of chronic ocular inflammation via upregulation of CTLA-4 and expansion of regulatory T cells

Suppressors of cytokine signaling (SOCS) proteins are negative-feedback regulators of the JAK/STAT pathway, and SOCS3 contributes to host immunity by regulating the intensity and duration of cytokine signals and inflammatory responses. Mice with Socs3 deletion in myeloid cells exhibit enhanced STAT3 signaling, expansion of Th1 and Th17 cells, and develop severe experimental autoimmune encephalomyelitis. Interestingly, development of the unique IL-17/IFN-γ double-producing (Th17/IFN-γ and Tc17/IFN-γ) subsets that exhibit strong cytotoxic activities and are associated with pathogenesis of several autoimmune diseases has recently been shown to depend on epigenetic suppression of SOCS3 expression, further suggesting involvement of SOCS3 in autoimmunity and tumor immunity. In this study, we generated mice with Socs3 deletion in the CD4 T cell compartment (CD4-SOCS3 knockout [KO]) to determine in vivo effects of the loss of Socs3 in the T cell-mediated autoimmune disease, experimental autoimmune uveitis (EAU). In contrast to the exacerbation of experimental autoimmune encephalomyelitis in myeloid-specific SOCS3-deleted mice, CD4-SOCS3KO mice were protected from acute and chronic uveitis. Protection from EAU correlated with enhanced expression of CTLA-4 and expansion of IL-10-producing regulatory T cells with augmented suppressive activities. We further show that SOCS3 interacts with CTLA-4 and negatively regulates CTLA-4 levels in T cells, providing a mechanistic explanation for the expansion of regulatory T cells in CD4-SOCS3 during EAU. Contrary to in vitro epigenetic studies, Th17/IFN-γ and Tc17/IFN-γ populations were markedly reduced in CD4-SOCS3KO, suggesting that SOCS3 promotes expansion of the Th17/IFN-γ subset associated with development of severe uveitis. Thus, SOCS3 is a potential therapeutic target in uveitis and other autoinflammatory diseases.