The protective function of invariant natural killer T cells in the relapse of experimental autoimmune uveoretinitis.

Experimental autoimmune uveoretinitis (EAU) in mice provides a useful platform to study the pathogenesis and experimental therapeutics of human uveitis. One often used EAU model employs C57BL/6 (B6) mice sensitized with a peptide residue having 1 to 20 amino acids of human interphotoreceptor retinoid binding protein (hIRBP1-20). The model using the B6 background has permitted a liberal use of genetically engineered strains and has provided insights for understanding uveoretinitis. However, this is usually acute/monophasic and does not represent human uveoretinitis that is characterized as a chronic/recurrent disease. Several chronic/recurrent EAU models have been developed; of these, we employed administration of staphylococcal enterotoxin B (SEB) for relapse in the present study, and found that recurrence was induced at day 24 after primary immunization, which is thought to be the convalescent phase. We reported the activation of invariant natural killer T (iNKT)-cells upon primary immunization of the EAU model mice with the ligand RCAI-56, which was found to mitigate the disease in our previous study. Here, we first attempted to ameliorate EAU in the relapse model using a preventive regimen by activating iNKT cells at the same time relapse induction (day 24) or in a regimen after 3 days of relapse induction (day 27). The preventive as well as post-inductive regimens were successful in reducing histopathological scores by inhibiting the Ag-specific Th17-biased response. Collectively, activation of iNKT cells may be useful to mitigate the relapse response of EAU induced with SEB.

Fungal-derived cues promote ocular autoimmunity through a Dectin-2/Card9-mediated mechanism.

Uveitis (intraocular inflammation) is a leading cause of loss of vision. Although its aetiology is largely speculative, it is thought to arise from complex genetic-environmental interactions that break immune tolerance to generate eye-specific autoreactive T cells. Experimental autoimmune uveitis (EAU), induced by immunization with the ocular antigen, interphotoreceptor retinoid binding protein (IRBP), in combination with mycobacteria-containing complete Freund's adjuvant (CFA), has many clinical and histopathological features of human posterior uveitis. Studies in EAU have focused on defining pathogenic CD4+ T cell effector responses, such as those of T helper type 17 (Th17) cells, but the innate receptor pathways precipitating development of autoreactive, eye-specific T cells remain poorly defined. In this study, we found that fungal-derived antigens possess autoimmune uveitis-promoting function akin to CFA in conventional EAU. The capacity of commensal fungi such as Candida albicans or Saccharomyces cerevisae to promote IRBP-triggered EAU was mediated by Card9. Because Card9 is an essential signalling molecule of a subgroup of C-type lectin receptors (CLRs) important in host defence, we evaluated further the proximal Card9-activating CLRs. Using single receptor-deficient mice we identified Dectin-2, but not Mincle or Dectin-1, as a predominant mediator of fungal-promoted uveitis. Conversely, Dectin-2 activation by α-mannan reproduced the uveitic phenotype of EAU sufficiently, in a process mediated by the Card9-coupled signalling axis and interleukin (IL)-17 production. Taken together, this report relates the potential of the Dectin-2/Card9-coupled pathway in ocular autoimmunity. Not only does it contribute to understanding of how innate immune receptors orchestrate T cell-mediated autoimmunity, it also reveals a previously unappreciated ability of fungal-derived signals to promote autoimmunity.

Carbon monoxide-releasing molecule-A1 (CORM-A1) improves clinical signs of experimental autoimmune uveoretinitis (EAU) in rats.

Uveitis is a sight-threatening inflammatory disease of the eye which represents the third leading cause of blindness in the developed countries. The conventional pharmacological treatment includes corticosteroids and immunosuppressive agents, which are limited by their side effects. New therapeutic strategies are thus strongly needed. Exogenously-administered carbon monoxide (CO) may represent an effective treatment for conditions characterized by a dysregulated inflammatory response. Carbon monoxide-releasing molecules (CORMs) are a novel group of compounds capable of carrying and liberating controlled quantities of CO. Among CORMs, CORM-A1 represents the first example of water soluble CO releaser. We show here that CORM-A1 under a late prophylactic regime is able to significantly ameliorate the natural course of experimental autoimmune uveoretinitis, a rodent model of immunoinflammatory posterior uveitis. The present study strongly supports the development of CORM-A1 as a potential new drug for treatment of patients with non-infectious posterior uveitis.

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 Cx 3 cr1 (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 (IRBP1-20). Disease severity was quantified with both clinical and histopathological grading. RESULTS: In the normal C57Bl/6 J Cx 3 cr1 (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 IRBP1-20, 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.

Ganciclovir attenuates the onset and progression of experimental autoimmune uveitis by inhibiting infiltration of Th17 and inflammatory cells into the retina.

Noninfectious (autoimmune and immune-mediated) uveitis is one of the primary diseases leading to blindness in the world. Due to the limitation of current first-line drugs for clinical uveitis, novel drugs and targets against uveitis are urgently needed. Ganciclovir (GCV), an FDA-approved antiviral drug, is often used to treat cytomegalovirus-induced retinitis in clinical patients. Recently, GCV was found to suppress neuroinflammation via targeting STING signaling because the STING pathway plays a pivotal role in autoimmune diseases. However, until now, the effect of GCV on non-infectious uveitis has never been explored. In this work, using the rat experimental autoimmune uveitis (EAU) model, we first found STING to be highly expressed in infiltrating cells (CD68+, CD45+, and CD4+) and retinal glial cells (Iba1+ and GFAP+) of the immunized retina. More importantly, GCV treatment can significantly suppress the initiation and progression of EAU by inhibiting infiltration of Th17 and inflammatory cells into the retina. Mechanistically, we found that GCV could reverse the levels of pro-inflammatory factors (such as IL-1ß) and chemokine-related factors (such as Cxcr3), possibly via targeting the STING pathway. The present results suggest that GCV may be considered as a novel therapeutic strategy against human uveitis.

Azithromycin modulates Teff/Treg balance in retinal inflammation via the mTOR signaling pathway.

Uveitis is one of the most common blindness-causing ocular disorders. Due to its complicated pathogenesis, the treatment of uveitis has been widely recognized as a challenge for ophthalmologists. Recently, the anti-inflammatory properties of the antibiotic Azithromycin (AZM) have been reported. However, the therapeutic effects of Azithromycin in experimental autoimmune uveitis (EAU), a representative model of human AU, have not been elucidated till date. We conducted this study to examine the therapeutic effects and potential mechanisms of Azithromycin in EAU. We observed that Azithromycin significantly attenuated retinal inflammation in EAU mice at day 14 after immunization along with a significantly decreased inflammatory cell infiltration and cytokine production in the retina. Furthermore, we observed that Azithromycin increased the number of regulatory T cells (Treg) and decreased the number of effector T cells (Teff) in both the draining lymph nodes and spleen of EAU mice. Additionally, Azithromycin suppressed the proliferation and activation of CD4 + T cells, and induced the apoptosis of CD4 + CD44 + memory T and CD4 + CXCR3 + Th1 cells. Mechanistically, we proved that Azithromycin could regulate Teff/Treg balance by inhibiting the phosphorylation of S6 ribosomal protein, a downstream target of mammalian target of rapamycin (mTOR). Together, our findings revealed that Azithromycin alleviated EAU by regulating the Teff/Treg balance through the mTOR signaling pathway, suggesting that Azithromycin could be a promising therapeutic candidate for AU.

Differential roles for IFN-gamma and IL-17 in experimental autoimmune uveoretinitis.

IL-17-producing CD4(+) T cells, so called T(h)17 cells, constitute a newly identified inflammatogenic cell population, which is critically involved in some inflammatory diseases. To explore the role of T(h)17 cells in murine experimental autoimmune uveoretinitis (EAU), a model of human autoimmune uveitis where T(h)1 responses predominantly participate in the pathogenesis, IL-17(-/-) mice were immunized with interphotoreceptor retinoid-binding protein peptide 1-20 for disease induction. Funduscopic examination revealed that EAU was induced in IL-17(-/-) mice just like in wild-type (WT) mice at early phases of the disease. However, at later/maintenance phases, the severity was significantly reduced in IL-17(-/-) mice. Expression of IFN-gamma and MCP-1 was comparable between WT and IL-17(-/-) mice during the time course. In vivo blockade of IFN-gamma and IL-4 resulted in exacerbation of EAU at later phases with augmented IL-17 production. Taken together, our data demonstrated that IL-17/T(h)17 participates in the late phases of EAU and also that T(h)1 and T(h)17 responses are differentially required for EAU.

Teriflunomide suppresses T helper cells and dendritic cells to alleviate experimental autoimmune uveitis.

Autoimmune uveitis (AU), a sight-threatening intraocular disorder, is still a challenge for ophthalmologists in clinic. Teriflunomide has been approved for multiple sclerosis (MS) in 2012 for its immunoregulatory function. However, the effect and mechanisms of teriflunomide in uveitis are still unknown. In this investigation, we used a murine model of non-infectious uveitis, experimental autoimmune uveitis (EAU), to explore the anti-inflammatory features of teriflunomide. Treatment with teriflunomide resulted in reduced clinical and pathological scores of retinal inflammations, accompanied by decreased intraocular infiltration of Th17 and Th1 cells in EAU mice. Meanwhile, teriflunomide treatment inhibited the proliferation and polarization of CD4+ T cells to Th17 and Th1 cells. Moreover, adoptive transfer of teriflunomide primed IRBP1-20-T cells failed to induce EAU. Interestingly, we found that teriflunomide suppressed the maturation and function of dendritic cells (DCs) both in vivo and in vitro. In conclusion, our findings suggest that teriflunomide alleviates inflammation in EAU mice by down-regulating Th17 and Th1 cells and suppresses the maturation and function of DCs for the first time.

Reactivation of uveitogenic T cells by retinal astrocytes derived from experimental autoimmune uveitis-prone B10RIII mice.

PURPOSE: To determine the involvement of retinal astrocytes (RACs) in T cell-mediated experimental autoimmune uveitis (EAU). METHODS: Frozen sections of eyes from naive mice or mice with EAU were stained for glial fibrillary acidic protein (GFAP) or major histocompatibility complex (MHC) class II molecules and were examined by confocal microscopy. RACs were isolated and cocultured with interphotoreceptor retinoid-binding protein (IRBP) peptide-specific T cells. The proliferation and cytokine production of responder T cells were determined by [(3)H]-thymidine incorporation and ELISA, respectively. RESULTS: The development of intraocular inflammation was associated with increased GFAP-positive cells in the retina. RACs from EAU-prone mice (B10RIII) activated uveitogenic T cells in vitro, enhanced T-cell proliferation and the production of proinflammatory cytokines, and increased the numbers of IL-17(+) IRBP T cells in the inflamed eye. The interaction between local RACs and IRBP-specific T cells was regulated by a distinct pattern of costimulatory molecules. In addition, the ability of IRBP-specific T cells to interact with RACs was dependent on whether the latter were derived from EAU-prone (B10RIII) or EAU-low susceptible (C57Bl/6) strains of mice. CONCLUSIONS: This study suggests that the RACs in EAU-prone mice contribute to the reactivation of pathogenic T cells in the eye, leading to intraocular inflammation and tissue damage.

Complement deposits on ocular tissues adjacent to sites of inflammation.

PURPOSE: The complement system plays important roles in a variety of chronic ocular diseases such as age-related macular degeneration. Here we examined the deposition of complement components in mouse eyes damaged by various mechanisms. METHODS: Mouse eyes were damaged by light or by three models of inflammation, i.e., local transgenic expression of cytokines, interleukin-1 or -7, or by induction of experimental autoimmune uveitis. Eye tissues obtained from each model were immunostained with antibodies against complement components C1q, C3, and C4. RESULTS: No complement deposition was seen in light damaged eyes, while in inflamed eyes we found complement deposition at sites of tissue damage and cellular infiltration. In addition to affected tissues, intense immunoreactivity against complement was unexpectedly observed in corneal tissues and lens capsule, despite lack of inflammation in these tissues. CONCLUSION: Our observations suggest that ocular tissues adjacent to inflammatory sites undergo changes that facilitate complement deposition.

[The Clinical Signs of Experimental Autoimmune Uveitis]. / Klinické projevy experimentální autoimunitní uveitidy.

INTRODUCTION: Autoimmune uveitis is a sight threatening disease which in many cases fails to respond to conventional immunosuppressive or biological therapy. The research in experimental models of autoimmune uveitis helps to find new therapeutical strategies. The aim of this study is to present the clinical and histological signs of experimental autoimmune uveitis (EAU) in mice. METHODS: EAU was induced in C57BL/6 mice by subcutaneous application of IRBP (interphotoreceptor retinoid binding protein) in complete Freunds adjuvant and intraperitoneal application of pertussis toxin. Clinical evaluation of uveitis was performed in vivo using special imaging system with otoscope. Histological evaluation of uveitis was performed at day 35 post induction of EAU on hematoxylin and eosin stained frozen sections. Clinical and histological grading was used to assess the inflammation intensity of EAU. RESULTS: The intensity of inflammation is depicted on representative fundus images and histological images of retina at day 35 post induction. CONCLUSION: The model of EAU is robust and reproducible and allows us to study the immunopathological mechanisms of inflammation and its regulation. The inflammatory signs in our model are similar to findings of posterior uveitis of autoimmune etiology in humans, thus we may apply our experimental results in human medicine.

Gut Microbial Alterations Associated With Protection From Autoimmune Uveitis.

PURPOSE: To investigate the contribution of the gut microbiota to the pathogenesis of uveitis. METHODS: Experimental 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. RESULTS: Broad-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. CONCLUSIONS: Oral 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.

CD73 Expressed on γδ T Cells Shapes Their Regulatory Effect in Experimental Autoimmune Uveitis.

γδ T cells can either enhance or inhibit an adaptive immune response, but the mechanisms involved are not fully understood. Given that CD73 is the main enzyme responsible for conversion of AMP into the immunosuppressive molecule adenosine, we investigated its role in the regulatory function of γδ T cells in experimental autoimmune uveitis (EAU). We found that γδ T cells expressed different amounts of CD73 during the different stages of EAU and that low CD73 expression on γδ T cells correlated with enhanced Th17 response-promoting activity. Functional comparison of CD73-deficient and wild-type B6 (CD73+/+) mice showed that failure to express CD73 decreased both the enhancing and suppressive effects of γδ T cells on EAU. We also demonstrated that γδ T cells expressed different amounts of CD73 when activated by different pathways, which enabled them to either enhance or inhibit an adaptive immune response. Our results demonstrate that targeting CD73 expression on γδ T cells may allow us to manipulate their pro- or anti-inflammatory effect on Th17 responses.

The effect of the CC chemokine receptor antagonist Met-RANTES on experimental autoimmune uveitis and oral tolerance.

Lymphocyte trafficking is controlled in part by the actions of chemokines. In rat experimental autoimmune uveitis (EAU) we observed differential therapeutic effects of Met-RANTES, a CCR1/CCR5 receptor antagonist, depending on the retinal antigen peptides inducing the disease and the time of application during the afferent or efferent immune response. CCR1 and/or CCR5 blockade may have inhibitory effects on different phases of the autoimmune response, depending on the antigen specificity of T cells in EAU. In contrast, Met-RANTES enhanced therapeutic oral tolerance independently of orally applied antigen.

CCR5-deficient mice develop experimental autoimmune uveoretinitis in the context of a deviant effector response.

PURPOSE: Experimental autoimmune uveoretinitis (EAU) is an organ-specific, Th1-cell-mediated disease that targets the neural retina. CCR5 is a chemokine receptor expressed on Th1 cells that promotes their migration. In CCR5-deficient mice, we examined the role of CCR5 in the development of EAU induced by immunization with interphotoreceptor retinoid-binding protein (IRBP) peptide. METHODS: Wild-type or CCR5-deficient B6 mice were immunized with human IRBP peptide 1-20 (hIRBP-p), and the severity of EAU was assessed clinically and histologically. Splenocytes and cells of regional lymph nodes near the eye were collected and their proliferation and production of IL-6, IL-10, IFN-gamma, and CCL2 (MCP-1) in response to hIRBP-p stimulation were measured. Moreover, the intraocular levels of these cytokines were analyzed. RESULTS: Immunization with hIRBP-p induced EAU in CCR5-deficient mice with a severity comparable to that in wild-type mice. Histologically, T-cell infiltration of the eye was reduced, but granulocyte infiltration was augmented in CCR5-deficient mice. Although splenic T cells from CCR5-deficient mice produced IFN-gamma but not IL-10 on stimulation by hIRBP-p, T cells from the regional lymph nodes failed to produce both cytokines. IL-6 production in the eye and IL-6 and CCL2 production by splenic T cells were predominantly augmented in CCR5-deficient mice. CONCLUSIONS: The development of EAU is not prevented in CCR5-deficient mice. Although T-cell infiltration into the eye is apparently reduced in CCR5-deficient mice, the defect is compensated for by granulocyte infiltration, supposedly mediated by augmented intraocular production of IL-6.

Suppression of immune-mediated ocular inflammation in mice by interleukin 1 receptor antagonist administration.

OBJECTIVE: To evaluate the effects of an interleukin 1 receptor antagonist (IL-1RA) on the development of immune-mediated ocular inflammation in mice. METHODS: Recombinant, human, nonglycosylated IL-1RA (anakinra [kineret]) was tested for its inhibitory effects in 2 systems: (1) experimental autoimmune uveitis induced by interphotoreceptor retinoid-binding protein in B10.A mice using routine procedures and evaluated by clinical and histological examination, and (2) ocular inflammation in mice induced by transfer of hen egg lysozyme-specific T cells to hen egg lysozyme-transgenic mice. Treatment with IL-1RA included daily subcutaneous injections of the drug, at 300 and 500 mg/kg, or phosphate-buffered saline as control. RESULTS: Mean +/- SE experimental autoimmune uveitis scores of histological ocular changes of the mice at day 14 postimmunization with interphotoreceptor retinoid-binding protein were 1.5 +/- 0.3 in control mice; 1.0 +/- 0.4 in 300-mg/kg anakinra-treated mice; and 0.5 +/- 0.2 in 500- mg/kg anakinra-treated mice (P = .004). There was a corresponding decrease in the cellular immune response and cytokine production of immune cells in treated mice. Suppression of ocular inflammation by anakinra in the transfer system was also observed (P = .04). CONCLUSION: Human IL-1RA suppresses immune-mediated ocular inflammation in mice, affecting both the afferent and efferent components of the pathogenic immune response.Clinical Relevance Systemic administration of IL-1RA may have clinical application in the management of patients with uveitis.

Interphotoreceptor retinoid-binding protein derived peptide can induce experimental autoimmune uveoretinitis in various rat strains.

Experimental autoimmune uveoretinitis (EAU) is an intraocular inflammatory disease model induced by retinal specific antigens such as S-antigen and interphotoreceptor retinoid-binding protein (IRBP). The present study was aimed at testing the uveitogenicity of IRBP and an IRBP-derived peptide in various strains of rats with different RT1 (major histocompatibility complex in rats) haplotypes. Immunization with IRBP induced distinct EAU in LEW (RT1l), WKAH (RT1k) W/M (RT1k), LEJ (RT1j), and BUF (RT1b) rats. IRBP also induced a low grade of EAU in SDJ (RT1u), but no disease was detected in TO rats, another strain of the RT1u haplotype. IRBP-derived peptide R16 (aa 1177-1191) induced severe EAU in LEW rats and moderate disease in the WKAH and W/M strains. Immunization with R16 also induced low levels of inflammation in eyes of 75% and 20% of LEJ and BUF rats, respectively, but this peptide did not cause any disease in SDJ and TO rats. Injection of Bordetella pertussis had minimum or no effect on the induction of EAU by peptide R16 in this study. These data thus indicate that peptide R16 can bind to various RT1 molecules in addition to RT1l. Further, our observations support the notion that certain epitopes of IRBP could be uveitogenic in humans with different HLA haplotypes.

Fas expression and apoptosis in rats with experimental autoimmune uveoretinitis.

PURPOSE: To evaluate Fas expression on CD4 and CD8 T cells in each organ at each stage of experimental autoimmune uveoretinitis (EAU) and apoptotic cells within EAU eyes. METHODS: Rats were immunized with the uveitopathogenic peptide derived from interphotoreceptor retinoid-binding protein. Flow cytometry was performed in ocular cells, draining lymph nodes cells and splenic cells of EAU rats to investigate Fas expression by CD4 and CD8 lymphocytes. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining of apoptotic nuclei was performed on sections of EAU eyes. RESULTS: Fas expression by both ocular and splenic CD4 and CD8 lymphocytes was significantly higher than in lymph nodes at each stage. In EAU eyes, there was a relatively large population of lymphocytes with Fas expression (19.6-25.6% of CD4 and 33.2-53.4% of CD8). Apoptotic cells were more prominent in the EAU eyes with established disease than in those with early or resolving disease. CONCLUSIONS: These results suggest that the relatively large population of lymphocytes with Fas expression in EAU eyes reflects the activation of lymphocytes in these eyes, and that the increase in apoptotic inflammatory cells at the peak of established disease may participate in the spontaneous disappearance of EAU.

Amelioration of experimental autoimmune uveoretinitis by inhibition of glyceraldehyde-derived advanced glycation end-product formation.

AGEs are permanently modified macromolecule derivatives that form through nonenzymatic glycation of amino groups of proteins. Glycer-AGEs are highly toxic and play an important role in the pathogenesis of chronic inflammatory diseases. However, the contribution of glycer-AGEs to the pathogenesis of uveitis is unclear. In this study, we measured serum levels of glycer-AGEs in 100 patients with endogenous uveitis (22 with HLA-B27-associated uveitis, 20 with VKH disease, 14 with Behçet's disease, and 44 with sarcoidosis) and 33 healthy volunteers. We then examined the effect of the AGE inhibitor in a mouse model of human endogenous uveitis (EAU) by continuous oral administration of pyridoxamine at 200 or 400 mg/kg/day. Regardless of the etiology, serum glycer-AGE levels were significantly higher in patients with uveitis than in healthy subjects. Treatment with 400 mg/kg pyridoxamine significantly reduced the clinical and histological severity of EAU and was accompanied by a significant decrease in serum and retinal glycer-AGE levels and suppression of translocation of NF-κB p65 into the nucleus of retinal cells. Serum glycer-AGE levels may therefore serve as a biomarker of human uveitis, as well as systemic inflammation, and may contribute to the progression of uveitis, including diabetic iritis, via the activation of NF-κB.

Aldose reductase deficiency protects from autoimmune- and endotoxin-induced uveitis in mice.

PURPOSE: To investigate the effect of aldose reductase (AR) deficiency in protecting the chronic experimental autoimmune (EAU) and acute endotoxin-induced uveitis (EIU) in c57BL/6 mice. METHODS: The WT and AR-null (ARKO) mice were immunized with human interphotoreceptor retinoid-binding peptide (hIRPB-1-20), to induce EAU, or were injected subcutaneously with lipopolysaccharide (LPS; 100 µg) to induce EIU. The mice were killed on day 21 for EAU and at 24 hours for EIU, when the disease was at its peak, and the eyes were immediately enucleated for histologic and biochemical studies. Spleen-derived T-lymphocytes were used to study the antigen-specific immune response in vitro and in vivo. RESULTS: In WT-EAU mice, severe damage to the retinal wall, especially to the photoreceptor layer was observed, corresponding to a pathologic score of ∼2, which was significantly prevented in the ARKO or AR inhibitor-treated mice. The levels of cytokines and chemokines increased markedly in the whole-eye homogenates of WT-EAU mice, but not in ARKO-EAU mice. Further, expression of inflammatory marker proteins such as inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-α, and vascular cell adhesion molecule (VCAM)-1 was increased in the WT-EIU mouse eyes but not in the ARKO-EIU eyes. The T cells proliferated vigorously when exposed to the hIRPB antigen in vitro and secreted various cytokines and chemokines, which were significantly inhibited in the T cells isolated from the ARKO mice. CONCLUSIONS: These findings suggest that AR-deficiency/inhibition protects against acute as well as chronic forms of ocular inflammatory complications such as uveitis.