Experimental Autoimmune Uveitis Mice Research Articles

Ly6Chi monocytes are required for mesenchymal stem/stromal cell-induced immune tolerance in mice with experimental autoimmune uveitis

The cells of the innate immune system, in addition to their capacity to elicit immunity, play a substantial role in immune tolerance induction. Our group has recently shown that a distinct subset of MHC IIhiB220hiCD11bmid suppressive macrophages is increased in the lung by intravenous (IV) administration of mesenchymal stem/stromal cells (MSC) and induces immune tolerance. Herein, we demonstrate that circulating CD11bhiLy6Chi monocytes are precursors to MHC IIhiB220hiCD11bmid macrophages in the lung and required for MSC-induced tolerance in a mouse model of experimental autoimmune uveitis (EAU). Analysis revealed that IV MSC induced an increase in IL-10-expressing MHC IIhiB220hiCD11bmid macrophages in the lung with a concomitant decrease in CD11bhiLy6Chi monocytes. Selective depletion of circulating CD11bhiLy6Chi cells abrogated the effects of MSC in the induction of IL-10hiMHC IIhiB220hiCD11bmid macrophages and immune tolerance in EAU mice. Similarly, an increase in CD4+CD25+Foxp3+ Tregs by MSCs was also reversed by CD11bhiLy6Chi cell depletion. These results suggest that CD11bhiLy6Chi monocytes are critical for MSC-induced immune tolerance.

NK cells are negatively regulated by sCD83 in experimental autoimmune uveitis

Natural killer (NK) cells represent a subset of lymphocytes that contribute to innate immunity and have been reported to play a role in autoimmune uveitis. However, the mechanisms regulating NK cellular function in this condition remain unclear. Herein, we investigated the status of NK cells in experimental autoimmune uveitis (EAU). We found that the number of CD83+CD3−NK1.1+ cells was increased in the inflamed eyes and spleens of the EAU mouse model. At the recovery stage of EAU, serum concentrations of soluble CD83 (sCD83) were increased. sCD83 treatment relieved retinal tissue damage and decreased the number of infiltrating NK cells in inflamed eyes. Further analysis of the effects of sCD83 treatment in EAU revealed that it reduced: 1) the expressions of CD11b and CD83 in NK cells, 2) the percent of CD11bhighCD27lowCD3−NK1.1+ cells and 3) the secretion of granzyme B, perforin and IFN-γ in NK cells as demonstrated both in vivo and in vitro. When sCD83 treated-NK cells were transferred into EAU mice, retinal tissue damage was relieved. These results demonstrate sCD83 down-regulate NK cellular function and thus provide important, new information regarding the means for the beneficial effects of this agent in the treatment of autoimmune uveitis.

Sodium butyrate regulates Th17/Treg cell balance to ameliorate uveitis via the Nrf2/HO-1 pathway

Autoimmune uveitis, a group of potentially blinding intraocular inflammatory diseases, remains a therapeutic challenge for ophthalmologists. Butyrates, which belong to the short-chain fatty acid family, possess immunomodulatory properties and therapeutic potential in several inflammatory disorders. However, the roles of butyrates in uveitis and their underlying immunomodulatory mechanisms remain elusive. Here, we report that treatment with sodium butyrate (NaB) significantly attenuated the ocular inflammatory response in mice with experimental autoimmune uveitis (EAU) at 14days after immunization, with significant decreases in inflammatory cell infiltration and inflammatory cytokine production in the retinas. Furthermore, NaB treatment decreased the frequency and number of Th17 cells and increased the frequency and number of T regulatory (Treg) cells in both draining lymph nodes and spleens of EAU mice. In vitro, NaB treatment directly converted the differentiation of naive T cells from Th17 cells toward Treg cells. Mechanistically, the NaB-mediated inhibition of Th17 cell differentiation may occur via inhibition of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1)/interleukin-6 receptor pathway. Moreover, the NaB-mediated inhibition on Th17 cell differentiation and uveitis were abrogated when an HO-1 inhibitor, SnPP, was used. These findings suggest that NaB inverts the differentiation of Th17 cells toward Treg cells and attenuates experimental autoimmune uveitis by modulating the Nrf2/HO-1 pathway.

Intravitreal injection of anti-Interleukin (IL)-6 antibody attenuates experimental autoimmune uveitis in mice

PurposeTo evaluate the effect of an intravitreally applied anti-IL-6 antibody for the treatment of experimental autoimmune uveitis (EAU). MethodsEAU was induced in female B10.RIII mice by Inter-Photoreceptor-Binding-Protein (IRBP) in complete Freund’s adjuvant, boosted by Pertussis toxin. Single blinded intravitreal injections of anti-IL-6 antibody were applied 5–7days as well as 8–10days (3day interval) after EAU induction into the randomized treatment eye and phosphate buffered saline (PBS) into the fellow control eye. Clinical and fluorescein angiography scoring (6 EAU grades) was done at each injection day and at enucleation day 14. Enucleated eyes were either scored histologically (6 EAU grades) or examined by ELISA for levels of IL-6, IL-17 and IL-6 soluble Receptor (sIL-6R). ResultsUveitis developed in all 12 mice. Clinical uveitis score was significantly reduced (p=0.035) in treated eyes (median 2.0, range 0–4.0, n=12) compared to the fellow control eyes (median 3.0, range 1.0–4.0, n=12). Angiography scores were reduced in 9/12 treated eyes and histological scores in 3/4 treated eyes compared to the fellow control eyes. Cytokine levels were determined in 8 mice, of which 4 responded to anti-IL-6 treatment and 4 did not respond. All mice responding to treatment had a significant reduction of IL-6 (p<0.01) and IL-17 (p=0.01) levels in treated eyes compared to the fellow control eyes. This difference was not seen in non-responding mice. ConclusionsIntravitreal anti-IL-6 treatment significantly attenuates experimental autoimmune uveitis in mice. EAU activity correlates with ocular IL-6 and IL-17 levels.

Correction: Regulation of Adenosine Deaminase on Induced Mouse Experimental Autoimmune Uveitis.

Liang, D., A. Zuo, R. Zhao, H. Shao, H. J. Kaplan, and D. Sun. 2016. Regulation of adenosine deaminase on induced mouse experimental autoimmune uveitis. J. Immunol . 196: [2646–2654][1]. The authors revised the grant footnote to include additional funding information. The corrected footnote is

TLR7 Engagement on Dendritic Cells Enhances Autoreactive Th17 Responses via Activation of ERK.

In this study, we showed that TLR7 activation significantly promoted interphotoreceptor retinoid-binding protein (IRBP)-specific Th17 responses by upregulating RORγt, IL-17, GM-CSF, and IL-23R expression in experimental autoimmune uveitis mice. In vivo administration of CL097 activated dendritic cells (DCs) and endowed them with an increased ability to activate IRBP-specific Th17 cells. CL097-treated DCs (CL097-DCs) formed a cytokine milieu that favored the generation and maintenance of Th17 cells by stimulating IL-1β, IL-6, and IL-23 expression. Furthermore, IRBP-specific T cells from immunized mice injected with CL097-DCs produced more IL-17 and transferred more severe experimental autoimmune uveitis than did those from mice injected with DCs. The enhanced immunostimulatory activities of CL097-DCs depended on JNK, ERK, and p38 activation. Blockade of ERK, but not p38 or JNK, completely abolished the Th17 responses induced by CL097-DCs. Collectively, our findings suggest that CL097 treatment significantly promotes autoreactive IL-17+ T cell responses through enhancing DC activation, which is mediated, at least in part, via the activation of ERK signaling.

Notch signalling suppresses regulatory T-cell function in murine experimental autoimmune uveitis.

Autoimmune uveitis is an intraocular inflammatory disorder in developed countries. Understanding the mechanisms underlying the development and modulation of immune reaction in uveitic eyes is critical for designing therapeutic interventions. Here we investigated the role of Notch signalling in regulatory T-cell (Treg cell) function during experimental autoimmune uveitis (EAU). Using the Foxp3-GFP reporter mouse strain, the significance of Notch signalling for the function of infiltrating Treg cells was characterized in an EAU model. We found that infiltrating Treg cells substantially expressed Notch-1, Notch-2, JAG1 and DLL1 in uveitic eyes. Activation of Notch signalling, represented by expression of HES1 and HES5, was enhanced in infiltrating Treg cells. Treatment with JAG1 and DLL1 down-regulated Foxp3 expression and immunosuppressive activity of isolated infiltrating Treg cells in vitro, whereas neutralizing antibodies against JAG1 and DLL1 diminished Notch ligand-mediated negative effects on Treg cells. To investigate the significance of Notch signalling for Treg cell function in vivo, lentivirus-derived Notch short hairpin RNAs were transduced into in vitro expanded Treg cells before adoptive transfer of Treg cells into EAU mice. Transfer of Notch-1-deficient Treg cells remarkably reduced pro-inflammatory cytokine production and inflammatory cell infiltration in uveitic eyes. Taken together, Notch signalling negatively modulates the immunosuppressive function of infiltrating Treg cells in mouse EAU.

AAV8-Mediated Angiotensin-Converting Enzyme 2 Gene Delivery Prevents Experimental Autoimmune Uveitis by Regulating MAPK, NF-κB and STAT3 Pathways

Renin angiotensin system (RAS) is a key hormonal system which regulates the cardiovascular function and is implicated in several autoimmune diseases. With the discovery of the angiotensin-converting enzyme 2 (ACE2), a protective axis of RAS namely ACE2/Ang-(1–7)/Mas that counteracts the deleterious ACE/AngII/AT1R axis has been established. This axis is emerging as a novel target to attenuate ocular inflammation. However, the underlying molecular mechanisms remain unclear. We investigated the hypothesis that enhancing the activity of the protective axis of RAS by subretinal delivery of an AAV8 (Y733F)-ACE2 vector would protect against the ocular inflammation in experimental autoimmune uveitis (EAU) mice through regulating the local immune responses. Our studies demonstrated that increased ACE2 expression exerts protective effects on inflammation in EAU mouse by modulating ocular immune responses, including the differentiation of Th1/Th17 cells and the polarization of M1/M2 macrophages; whereas the systemic immune responses appeared not affected. These effects were mediated by activating the Ang-(1–7)/Mas and inhibiting the MAPK, NF-κB and STAT3 signaling pathways. This proof-of-concept study suggests that activation of ocular ACE2/Ang-(1–7)/Mas axis with AAV gene transfer modulates local immune responses and may be a promising, long-lasting therapeutic strategy for refractory and recurrent uveitis, as well as other inflammatory eye diseases.

Gut Microbial Alterations Associated With Protection From Autoimmune Uveitis.

PurposeTo investigate the contribution of the gut microbiota to the pathogenesis of uveitis.MethodsExperimental autoimmune uveitis (EAU) in B10.RIII mice was induced using interphotoreceptor binding protein peptide. Mice were treated with oral or intraperitoneal (IP) antibiotics. Effector (Teff) and regulatory (Treg) T lymphocytes were identified using flow cytometry; 16S rRNA gene sequencing and qPCR were performed on gastrointestinal (GI) contents.ResultsBroad-spectrum (four antibiotics given simultaneously) oral, but not IP, antibiotics reduced mean uveitis clinical scores significantly compared with water-treated animals (0.5 vs. 3.0, P < 0.0001 for oral; 3.4 vs. 3.4, P > 0.99 for IP). Both oral metronidazole (P = 0.02) and vancomycin (P < 0.0001) alone decreased inflammation, whereas neomycin (P = 0.7) and ampicillin (P = 0.4) did not change mean uveitis scores. Oral broad-spectrum antibiotics increased Tregs in the GI lamina propria of EAU animals at 1 week, and in extraintestinal lymphoid tissues later, whereas Teff and inflammatory cytokines were reduced. 16S sequencing of GI contents revealed altered microbiota in immunized mice compared with nonimmunized mice, and microbial diversity clustering in EAU mice treated with uveitis-protective antibiotics. Experimental autoimmune uveitis mice also demonstrated gut microbial diversity clustering associated with clinical score severity.ConclusionsOral antibiotics modulate the severity of inducible EAU by increasing Tregs in the gut and extraintestinal tissues, as well as decreasing effector T cells and cytokines. 16S sequencing suggests that there may be protective and, conversely, potentially uveitogenic, gut microbiota. These findings may lead to a better understanding of how uveitis can be treated or prevented by modulating the gut microbiome.

Blockade of Extracellular ATP Effect by Oxidized ATP Effectively Mitigated Induced Mouse Experimental Autoimmune Uveitis (EAU).

Various pathological conditions are accompanied by ATP release from the intracellular to the extracellular compartment. Extracellular ATP (eATP) functions as a signaling molecule by activating purinergic P2 purine receptors. The key P2 receptor involved in inflammation was identified as P2X7R. Recent studies have shown that P2X7R signaling is required to trigger the Th1/Th17 immune response, and oxidized ATP (oxATP) effectively blocks P2X7R activation. In this study we investigated the effect of oxATP on mouse experimental autoimmune uveitis (EAU). Our results demonstrated that induced EAU in B6 mice was almost completely abolished by the administration of small doses of oxATP, and the Th17 response, but not the Th1 response, was significantly weakened in the treated mice. Mechanistic studies showed that the therapeutic effects involve the functional change of a number of immune cells, including dendritic cells (DCs), T cells, and regulatory T cells. OxATP not only directly inhibits the T cell response; it also suppresses T cell activation by altering the function of DCs and Foxp3+ T cell. Our results demonstrated that inhibition of P2X7R activation effectively exempts excessive autoimmune inflammation, which may indicate a possible therapeutic use in the treatment of autoimmune diseases.

Digoxin Inhibits Induction of Experimental Autoimmune Uveitis in Mice, but Causes Severe Retinal Degeneration.

PurposeDigoxin, a major medication for heart disease, was recently reported to have immunosuppressive capacity. Here, we determined the immunosuppressive capacity of digoxin on the development of experimental autoimmune uveitis (EAU) and on related immune responses.MethodsThe B10.A mice were immunized with interphotoreceptor retinoid-binding protein (IRBP) and were treated daily with digoxin or vehicle control. On postimmunization day 14, the mouse eyes were examined histologically, while spleen cells were tested for cytokine production in response to IRBP and purified protein derivative. The immunosuppressive activity of digoxin was also tested in vitro, by its capacity to inhibit development of Th1 or Th17 cells. To investigate the degenerative effect of digoxin on the retina, naïve (FVB/N × B10.BR)F1 mice were similarly treated with digoxin and tested histologically and by ERG.ResultsTreatment with digoxin inhibited the development of EAU, as well as the cellular response to IRBP. Unexpectedly, treatment with digoxin suppressed the production of interferon-γ to a larger extent than the production of interleukin 17. Importantly, digoxin treatment induced severe retinal degeneration, determined by histologic analysis with thinning across all layers of the retina. Digoxin treatment also induced dose-dependent vision loss monitored by ERG on naïve mice without induction of EAU.ConclusionsTreatment of mice with digoxin inhibited the development of EAU and cellular immune response to IRBP. However, the treatment induced severe damage to the retina. Thus, the use of digoxin in humans should be avoided due to its toxicity to the retina.

Vorinostat Modulates the Imbalance of T Cell Subsets, Suppresses Macrophage Activity, and Ameliorates Experimental Autoimmune Uveoretinitis

The purpose of the study was to investigate the anti-inflammatory efficiency of vorinostat, a histone deacetylase inhibitor, in experimental autoimmune uveitis (EAU). EAU was induced in female C57BL/6J mice immunized with interphotoreceptor retinoid-binding protein peptide. Vorinostat or the control treatment, phosphate-buffered saline, was administrated orally from 3days before immunization until euthanasia at day 21 after immunization. The clinical and histopathological scores of mice were graded, and the integrity of the blood-retinal barrier was examined by Evans blue staining. T helper cell subsets were measured by flow cytometry, and the macrophage functions were evaluated with immunohistochemistry staining and immunofluorescence assays. The mRNA levels of tight junction proteins were measured by qRT-PCR. The expression levels of intraocular cytokines and transcription factors were examined by western blotting. Vorinostat relieved both clinical and histopathological manifestations of EAU in our mouse model, and the BRB integrity was maintained in vorinostat-treated mice, which had less vasculature leakage and higher mRNA and protein expressions of tight junction proteins than controls. Moreover, vorinostat repressed Th1 and Th17 cells and increased Th0 and Treg cells. Additionally, the INF-γ and IL-17A expression levels were significantly decreased, while the IL-10 level was increased by vorinostat treatment. Furthermore, due to the reduced TNF-α level, the macrophage activity was considerably inhibited in EAU mice. Finally, transcription factors, including STAT1, STAT3, and p65, were greatly suppressed by vorinostat treatment. Our data suggest that vorinostat might be a potential anti-inflammatory agent in the management of uveitis and other autoimmune inflammatory diseases.

Modulating of ocular inflammation with macrophage migration inhibitory factor is associated with notch signalling in experimental autoimmune uveitis.

The aim of this study was to examine whether macrophage migration inhibitory factor (MIF) could exaggerate inflammatory response in a mouse model of experimental autoimmune uveitis (EAU) and to explore the underlying mechanism. Mutant serotype 8 adeno-associated virus (AAV8) (Y733F)-chicken β-actin (CBA)-MIF or AAV8 (Y733F)-CBA-enhanced green fluorescent protein (eGFP) vector was delivered subretinally into B10.RIII mice, respectively. Three weeks after vector delivery, EAU was induced with a subcutaneous injection of a mixture of interphotoreceptor retinoid binding protein (IRBP) peptide with CFA. The levels of proinflammatory cytokines were detected by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Retinal function was evaluated with electroretinography (ERG). We found that the expression of MIF and its two receptors CD74 and CD44 was increased in the EAU mouse retina. Compared to AAV8.CBA.eGFP-injected and untreated EAU mice, the level of proinflammatory cytokines, the expression of Notch1, Notch4, delta-like ligand 4 (Dll4), Notch receptor intracellular domain (NICD) and hairy enhancer of split-1 (Hes-1) increased, but the ERG a- and b-wave amplitudes decreased in AAV8.CBA.MIF-injected EAU mice. The Notch inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) reduced the expression of NICD, Hes-1 and proinflammatory cytokines. Further, a MIF antagonist ISO-1 attenuated intraocular inflammation, and inhibited the differentiation of T helper type 1 (Th1) and Th17 in EAU mice. We demonstrated that over-expression of MIF exaggerated ocular inflammation, which was associated with the activation of the Notch signalling. The expression of both MIF and its receptors are elevated in EAU mice. Over-expression of MIF exaggerates ocular inflammation, and this exaggerated inflammation is associated with the activation of the Notch signalling and Notch pathway. Our data suggest that the MIF-Notch axis may play an important role in the pathogenesis of EAU. Both the MIF signalling pathways may be promising targets for developing novel therapeutic interventions for uveitis.

The critical points in induction of experimental autoimmune uveitis

Autoimmune uveitis is a leading cause of visual impairment in developed countries in patients of working age. Animal models of experimental autoimmune uveitis (EAU) have been established to serve as a useful template for novel therapeutic approaches. Experimental autoimmune uveitis is induced in C57BL/6 mice by subcutaneous application of interphotoreceptor retinoid binding protein in complete Freund's adjuvant and pertussis toxin. Clinical and histological grading is used to assess the inflammation intensity of EAU. The protocol of induction of EAU in mice hides several important aspects, which are crucial for developing the disease. These details have to be addressed to ensure reproducible disease induction. We describe our experience in establishing the model by pointing out the critical steps in EAU protocol which we found important. The mouse model of EAU has practical value for preclinical studies, is robust and well established. However, the induction of inflammation of the eye can be quite challenging when important details of the protocol are not recognized and adhered to.

Inhibition of Noninfectious Uveitis Using Intravenous Administration of Collagen II-Specific Type 1 Regulatory T Cells.

To evaluate the therapeutic potential of Col-Treg, a collagen II-specific type 1 regulatory T-cell immunotherapy for the treatment of noninfectious uveitis (NIU). Col-Treg cells were produced from collagen II-specific T cell receptor (TCR) transgenic mice or peripheral blood of healthy donors. Phenotypic characterization was performed by flow cytometry, and cytokine secretion was evaluated with Flowcytomix or ELISA. In vitro functional characterization included ATP hydrolysis, cytotoxicity, and contact-independent T-cell suppression and plasticity assays. Col-Treg migration was assessed by quantitative PCR specific to Col-Treg TCR. Col-Treg cells were administered intravenously in mice displaying experimental autoimmune uveitis (EAU) induced by interphotoreceptor retinoid-binding protein (IRBP) immunizations. Efficacy of Col-Treg was assessed by ophthalmology, histology, and immunohistochemistry. Mice Col-Treg cells displayed identity features of type 1 Treg cells with expression of CD25, FoxP3, low surface expression of CD127, and cytokine secretion profile (IL-10(high), IL-4(low), IFN-γ(int)). In vitro functional assays demonstrated Col-Treg suppressive capacity via soluble factor-dependent immunosuppression, cytotoxicity, and ATP hydrolysis. Col-Treg cells expressed granzyme B, CD39, and glucocorticoid-induced TNF-related protein (GITR). Administration of Col-Treg in EAU mice inhibited clinical and morphologic signs of uveitis and decreased ocular leukocyte infiltration. Col-Treg cells homed in the ocular tissues 24 hours after intravenous injection. Human Col-Treg cells were comparable to mice Col-Treg cells in identity and function and did not show the capacity to differentiate into Th17 cells in vitro. These results demonstrate the therapeutic potential of Col-Treg cells as a targeted approach for the treatment of NIU and the feasibility of translating this approach to the human clinical setting.

The P2X7 receptor is a potential therapeutic target for the treatment of Uveitis

PurposeAdenosine‐5′‐triphosphate (ATP) functions as an important extracellular messenger and plays a critical role as a danger signalling molecule during inflammation. In pathological conditions damaged cells leak high concentrations of ATP into the extracellular milieu, activating P2 Purinergic receptors which are highly expressed on immune cells. Pathological stimulation of the P2X7 receptor may be involved in the development of autoimmune disease, so we explored the impact of P2X7R antagonist treatment on the development of Experimental Autoimmune Uveitis (EAU) in mice.MethodsEAU was induced in P2X7‐/‐ and wild‐type mice using IRBP peptide 1‐20(GPTHLFQPSLVLDMAKVLLD) with adjuvant Bordetella pertussis toxin. All procedures were performed under a Home Office License in accordance with the regulations of UK ASPA (1986). EAU was then induced in B10.rIII mice with RBP‐3 161‐180 (SGIPYIISYLHPGNTILHVD) and adjuvant Bordetella pertussis toxin. P2X7R antagonist A439079275 or vehicle were injected i.p. twice daily from day 12. p.i when clinical features of EAU manifested. Disease activity was observed through TEFI imaging and animals were treated until peak disease and termination at day 16 p.i.ResultsP2X7R deficiency protected against the development of EAU, with disease scores significantly lower in P2X7‐/‐ animals compared to control animals. P2X7R antagonist treatment with A439079 prevented development of severe EAU with disease scores in A439079 treated animals significantly lower than vehicle treated animals.ConclusionsP2X7R deficiency protects against the development of EAU in mice and P2X7R antagonist can ameliorate established disease. The P2X7R may represent a viable therapeutic target for ocular inflammatory disease.

Dietary Omega-3 Fatty Acids Suppress Experimental Autoimmune Uveitis in Association with Inhibition of Th1 and Th17 Cell Function.

Omega (ω)–3 long-chain polyunsaturated fatty acids (LCPUFAs) inhibit the production of inflammatory mediators and thereby contribute to the regulation of inflammation. Experimental autoimmune uveitis (EAU) is a well-established animal model of autoimmune retinal inflammation. To investigate the potential effects of dietary intake of ω-3 LCPUFAs on uveitis, we examined the anti-inflammatory properties of these molecules in comparison with ω-6 LCPUFAs in a mouse EAU model. C57BL/6 mice were fed a diet containing ω-3 LCPUFAs or ω-6 LCPUFAs for 2 weeks before as well as after the induction of EAU by subcutaneous injection of a fragment of human interphotoreceptor retinoid-binding protein emulsified with complete Freund’s adjuvant. Both clinical and histological scores for uveitis were smaller for mice fed ω-3 LCPUFAs than for those fed ω-6 LCPUFAs. The concentrations of the T helper 1 (Th1) cytokine interferon-γ and the Th17 cytokine interleukin-17 in intraocular fluid as well as the production of these cytokines by lymph node cells were reduced for mice fed ω-3 LCPUFAs. Furthermore, the amounts of mRNAs for the Th1- and Th17-related transcription factors T-bet and RORγt, respectively, were reduced both in the retina and in lymph node cells of mice fed ω-3 LCPUFAs. Our results thus show that a diet enriched in ω-3 LCPUFAs suppressed uveitis in mice in association with inhibition of Th1 and Th17 cell function.

CTLA4-Ig suppresses development of experimental autoimmune uveitis in the induction and effector phases: Comparison with blockade of interleukin-6

Recently, a number of biologics have been used in the treatment of autoimmune diseases. However, in the treatment of severe autoimmune uveitis, only TNF-alpha inhibitors are preferably used and the effect of other biologics such as interleukin-6 (IL-6) signaling blockade or cytotoxic T-lymphocyte antigen-4–immunoglobulin fusion protein (CTLA4-Ig) has not been well studied. Previously, we reported that IL-6 blockade effectively suppresses the development of experimental autoimmune uveitis (EAU), a mouse model for uveitis, by inhibiting Th17 cell development. In this study, we investigated the effect of CTLA4-Ig on EAU development and compared it with the effect of anti-IL-6 receptor monoclonal antibody (MR16-1). C57BL/6J mice were immunized with interphotoreceptor retinoid-binding protein (IRBP) and treated once with CTLA4-Ig or MR16-1. Both CTLA4-Ig and MR16-1 administered in the induction phase (the same day as immunization) significantly reduced the clinical and histopathological scores of EAU. Fluorescence-activated cell sorting studies using draining lymph node (LN) cells from EAU mice 10 days after immunization showed that CTLA4-Ig can suppress early T-helper cell activation. CTLA4-Ig administered in the effector phase of the disease (one week after immunization), when IRBP-reactive T cells have been primed, also significantly reduced the clinical and histopathological scores of EAU. In contrast, MR16-1 administered in the effector phase did not ameliorate EAU. To investigate the differences between these biologics in the effector phase, in vitro restimulation analysis of LN cells obtained from EAU mice one week after immunization was performed and revealed that CTLA4-Ig, but not MR16-1, added to culture media could inhibit the proliferation of IRBP-specific CD4+ T cells which possessed capacities of producing IFN-gamma and/or IL-17. Collectively, CTLA4-Ig ameliorated EAU through preventing initial T-cell activation in the induction phase and suppressing proliferation of IRBP-specific T cells in the effector phase. Blockade of IL-6 signaling did not have such inhibitory effects after T-cell priming. CTLA4-Ig may have therapeutic effects on human chronic uveitis.

Attenuating effect of chrysin on experimental autoimmune uveitis and its mechanism

Background Chrysin has many biological activities, and its anti-inflammatory effect has been confirmed. However, whether it can treat experimental autoimmune uveitis (EAU) is still not elucidated. Objective This study was to investigate the therapeutic effect of chrysin on EAU and explore the potential mechanism. Methods EAU animal models were established in 30 SPF C57BL/6J mice by the subcutaneous injection and ball pad injection of interphotoreceptor retinoid binding protein1-20 (IRBP1-20)/complete Freund adjuvant (CFA), and then the models were randomized into the model control group and chrysin-treated group. Chrysin solution dissolved by 10 μl dimethyl sulfoxide (DMSO)+ 140 μl PBS was administrated by gavaging in the mice with the dose 25 mg/kg from 3 days before immunization through 21 days everyday in the chrysin group, and equal volume of solvent was used in the same way in the model control group. Retinas were examined by indirect ophthalmoscope once per day, and inflammation and pathological scores of retina were performed based on the criteria of Caspi on the 21st day after injection. The apoptosis of retinal cells was assayed by TUNEL staining, and the relative expressions of pro-inflammatory cytokines interferon-γ (IFN-γ), interleukin-17A (IL-17A), IL-6 and tumor necrosis factor-α (TNF-α) and signal transducer and activator of transcription 1 (STAT1), STAT3, p-STAT1, p-STAT3 in mouse retinas were detected by Western blot. Results Compared with the model control group, the inflammation scores and pathological scores of retinal inflammation were significantly reduced in the chrysin group (inflammation scores: 0.50±0.45 vs 1.58±0.92, t=2.600, P=0.026; pathologic scores: 0.58±0.38 vs 1.83±0.75, t=3.638, P=0.005). The infiltration of a large number of inflammatory cells, retinal vasculitis and granulomatous lesions were found in mouse retinas in the model control group, however, the morphology of mouse retinas in the chrysin group was normal based on hematoxylin-eosin staining. The number of apoptotic cells was remarkable lessened in the chrysin group compared with the model control group under the fluorescence microscope. Western blot assay resolved that significantly down-regulation in the expressions of IFN-γ, IL-17A, IL-6 and TNF-α was seen in the chrysin group in comparison with the model control group (t=7.802, P=0.001; t=14.906, P=0.000; t=10.241, P=0.001; t=3.304, P=0.030), and the relative expression levels of STAT1, STAT3, p-STAT1 and p-STAT3 were considerably lower in the chrysin group than those in the model control group (t=8.965, P=0.001; t=8.358, P=0.001; t=4.864, P=0.031; t=4.730, P=0.009). Conclusions Chrysin or chrysin-like flavonoids ameliorate intraocular inflammatory symptoms in EAU mice by inhibiting the activity of STAT signal pathway. Key words: Flavonoids/pharmacology; Immunosuppressive agents/pharmacology; Autoimmune diseases; Uveitis/immunology; Disease models, animal; Signal transducer and activator of transcription; T-lymphocytes/drug effects

Experimental autoimmune uveitis and other animal models of uveitis: An update.

Over the past several decades, animal models of autoimmune uveitis directed at eye-specific antigens (Ags) have been developed. These have allowed researchers to understand the basic mechanisms that lead to these diseases and also recently helped the researchers in translational research for therapeutic interventions. Experimental autoimmune uveitis (EAU) is an animal disease model of human endogenous uveitis and can be induced in susceptible animals by immunization with retinal Ags. Ever since the first description of EAU in mice in 1988, several animal models of uveitis has been described by researchers. Disease-specific model for cytomegalovirus retinitis and tubercular uveitis has evolved our understanding of these complex entities. Endotoxin induced uveitis is another useful model for anterior uveitis, which is not an autoimmune process and is triggered by injection of bacterial endotoxin (lipopolysaccharides) resulting in a rapid short lasting uveitis. The current article will give an insight into the various EAU animal models and their current implications in translational research. The article will also highlight the different grading systems for EAU in the animal model.