Pathogenesis Of Experimental Autoimmune Uveoretinitis Research Articles

Adenovirus-mediated down-regulation of miR-21-5p alleviates experimental autoimmune uveoretinitis in mice

MiR-21-5p has been found to be up-regulated in the retina of experimental autoimmune uveoretinitis (EAU) mice and correlated with the pathogenesis of EAU. The objective of the present study is to explore the role of miR-21-5p in EAU. C57 mice were immunized with residue1–20 (IRBP1–20) in complete Freund's adjuvant supplemented with Mycobacterium tuberculosis H37Ra to induce EAU, and miR-21-5p was knocked down via subretinal injection of anti-miR-21-5p adenovirus. The pathological score, TUNEL positive cells and the expression of pro-inflammatory factors in the retina were reduced, and the expression of IL-10 was increased by down-regulation of miR-21-5p. Up-regulation of miR-21-5p significantly decreased the mRNA and protein levels of IL-10 in ARPE-19 cells. The binding activity of miR-21-5p on the 3′UTR of IL-10 mRNA was confirmed by luciferase reporter assay. Moreover, the miR-21-5p level in splenic lymphocytes of EAU mice was increased at the 7th day after immunization and reached its peak at the 14th day, that was in accordance with the changing trend with the Th17 cell frequency in the spleen. Besides, lentivirus-mediated down-regulation of miR-21-5p reduced the Th17 cell frequency and increased the Treg cell fraction of IRBP1–20-stimulated lymphocytes in vitro. Taken together, in situ down-regulation of miR-21-5p attenuates EAU by inhibiting inflammatory responses and reducing retinal cell apoptosis. miR-21-5p may also participate in the progress of EAU by affecting Th17/Treg balance via the regulation of IL-10. Therefore, we demonstrate that miR-21-5p can serve as a therapeutic target in the management of uveitis and other autoimmune diseases.

Crucial role of P2X7 receptor for effector T cell activation in experimental autoimmune uveitis.

To investigate the roles of P2X7 receptors (P2RX7) in the pathogenesis of experimental autoimmune uveoretinitis (EAU). Experimental. Either wild-type (P2rx7 +/+ ) or P2rx7-deficient (P2rx7 -∕- ) mice were immunized with interphotoreceptor retinoid-binding protein (IRBP) peptide 1-20. Severity of EAU was evaluated clinically and histopathologically. The induction of IRBP-specific proliferation and cytokines in draining lymph nodes was assessed by enzyme-linked immunosorbent assays (ELISA). The frequency of activation markers was examined by flow cytometry. Furthermore, inhibitory roles of systemic administration of Brilliant Blue G (BBG), an antagonist for P2RX7, in EAU were also assessed in the wild-type mice. The severity of EAU in P2rx7 -∕- mice was reduced as compared with that in P2rx7 +/+ mice, both clinically and histopathologically. IRBP-specific proliferation in P2rx7 -∕- on day 16 was slightly decreased compared to that in P2rx7 +/+ mice. The induction of IRBP-specific interferon (IFN)-γ and interleukin (IL)-17 in P2rx7 -∕- mice on day 16 was lower than that in P2rx7 +/+ mice. The up-regulation of surface expression of activation markers such as CD25, CD44, and CD69 in response to TCR stimulation in P2rx7 -∕- mice was decreased as compared with that in P2rx7 +/+ mice. Furthermore, neutralization of P2RX7 in vivo by BBG suppressed EAU clinically and histopathologically. IRBP-specific IFN-γ and IL-17 induction in BBG-treated mice was significantly lower than that in vehicle-treated mice. The results suggest that P2RX7 is a novel preventative therapeutic target for uveitis as it suppresses the effector functions of both Th1 and Th17 cell responses.

C-Type Lectin-Like Receptors As Emerging Orchestrators of Sterile Inflammation Represent Potential Therapeutic Targets.

Over the last decade, C-type lectin-like receptors (CTLRs), expressed mostly by myeloid cells, have gained increasing attention for their role in the fine tuning of both innate and adaptive immunity. Not only CTLRs recognize pathogen-derived ligands to protect against infection but also endogenous ligands such as self-carbohydrates, proteins, or lipids to control homeostasis and tissue injury. Interestingly, CTLRs act as antigen-uptake receptors via their carbohydrate-recognition domain for internalization and subsequent presentation to T-cells. Furthermore, CTLRs signal through a complex intracellular network leading to the secretion of a particular set of cytokines that differently polarizes downstream effector T-cell responses according to the ligand and pattern recognition receptor co-engagement. Thus, by orchestrating the balance between inflammatory and resolution pathways, CTLRs are now considered as driving players of sterile inflammation whose dysregulation leads to the development of various pathologies such as autoimmune diseases, allergy, or cancer. For examples, the macrophage-inducible C-type lectin (MINCLE), by sensing glycolipids released during cell-damage, promotes skin allergy and the pathogenesis of experimental autoimmune uveoretinitis. Besides, recent studies described that tumors use physiological process of the CTLRs’ dendritic cell-associated C-type lectin-1 (DECTIN-1) and MINCLE to locally suppress myeloid cell activation and promote immune evasion. Therefore, we aim here to overview the current knowledge of the pivotal role of CTLRs in sterile inflammation with special attention given to the “Dectin-1” and “Dectin-2” families. Moreover, we will discuss the potential of these receptors as promising therapeutic targets to treat a wide range of acute and chronic diseases.

Expression Analysis of Cytokine and Chemokine Genes during the Natural Course of Murine Experimental Autoimmune Uveoretinitis

C57BL/6 mice were immunized with human interphotoreceptor retinoid-binding protein peptides to induce experimental autoimmune uveoretinitis (EAU). From the day of immunization to 30 days later, RNA was isolated daily from the mouse eyes. Dynamic changes in gene expression during the pathogenesis of EAU were analyzed by TaqMan gene expression assay that contained most chemokines/cytokines and their receptors, and signal transducer and activator of transcription (STAT) family genes, using beta-actin as the endogenous control. Gene clusters based on their expression profiles were analyzed to determine the candidate genes for the pathogenesis of inflammation. Hierarchical cluster analysis showed gene expression during EAU development in seven clustering patterns. Hierarchical cluster analysis also identified four distinct phases in daily expression: entrance, acceleration, deceleration, and remission. Gene expression changes in the EAU active phase showed synergetic upregulation of Th1-type genes (IFN-gamma and CXCL10/IP-10) with elevated Th2-type genes (CCL17/TARC and IL-5). Sequential expression changes of STAT1, STAT6, and STAT3 genes represented the dynamic changes of Th1, Th2, and Th17-type inflammatory genes, respectively. The expression pattern of STAT1 was representative of many gene movements. Our results suggested that coordinated action of Th1, Th2, and Th17 genes and STAT family genes are involved in EAU development and resolution.

Local Activation of Dendritic Cells Alters the Pathogenesis of Autoimmune Disease in the Retina

Interest in the identities, properties, functions, and origins of local APC in CNS tissues is growing. We recently reported that dendritic cells (DC) distinct from microglia were present in quiescent retina and rapidly responded to injured neurons. In this study, the disease-promoting and regulatory contributions of these APC in experimental autoimmune uveoretinitis (EAU) were examined. Local delivery of purified, exogenous DC or monocytes from bone marrow substantially increased the incidence and severity of EAU induced by adoptive transfer of activated, autoreactive CD4 or CD8 T cells that was limited to the manipulated eye. In vitro assays of APC activity of DC from quiescent retina showed that they promoted generation of Foxp3(+) T cells and inhibited activation of naive T cells by splenic DC and Ag. Conversely, in vitro assays of DC purified from injured retina demonstrated an enhanced ability to activate T cells and reduced induction of Foxp3(+) T cells. These findings were supported by the observation that in situ activation of DC before adoptive transfer of β-galactosidase-specific T cells dramatically increased severity and incidence of EAU. Recruitment of T cells into retina by local delivery of Ag in vivo showed that quiescent retina promoted development of parenchymal Foxp3(+) T cells, but assays of preinjured retina did not. Together, these results demonstrated that local conditions in the retina determined APC function and affected the pathogenesis of EAU by both CD4 and CD8 T cells.

TH1 AND TH2 RESPONSES IN PATHOGENESIS AND REGULATION OF EXPERIMENTAL AUTOIMMUNE UVEORETINITIS

Experimental autoimmune uveoretinitis (EAU) in animals can be induced by immunization with retinal antigens or their fragments and represents human uveitis of putative autoimmune origin. The pathogenesis of EAU, and likely also of human uveitis, involves cell-mediated destruction of retinal tissues that is dependent on retinal antigen-specific T cells. Because in most cases a Th1-type response has been implicated in path ogenesis, the prevailing consensus has been that immunoregulatory manipulations designed to enhance the Th2 response at the expense of the Th1 response will be bene-ficial in clinical treatment of uveitis. This assumption may not always be correct. The present review will summarize the evidence that, despite a central role for Th1 response in uveitis, an unopposed Th2-like response can be equally or more destructive to the retinal tissues. Furthermore, the Th1 response itself triggers regulatory circuits that feed back and dampen further recruitment of antigen-specific T cells into the Th1 effector pool. Thus, although the Th1 effector response can and does result in retinal pathology, immunoregulatory strategies must take into account that immune deviation therapies designed to replace the Th1 with a Th2 response might result in exchanging one type of pathology for another rather than in achieving the desired therapeutic effect.

Chemokine gene expression in iris-ciliary body during experimental autoimmune uveoretinitis

Purpose. To evaluate, through differential gene expression of chemokines in iris-ciliary body (I/CB), the extent to which leukocyte recruitment to the ocular anterior segment participates in the pathogenesis of experimental autoimmune uveoretinitis (EAU) in mice. Methods. B10.A mice were immunized with 50 µg of inter-photoreceptor retinoid binding protein (IRBP) mixed with complete Freund's adjuvant. Aqueous humor (AqH) was collected at 0, 11, 17, and 28 days and assayed for leukocyte content and protein levels. Enucleated eyes were subjected to histologic analysis. Chemokine gene expression in I/CB was determined at these same time points by a multiprobe ribonuclease protection assay (RPA) system. Results. Inflammation was detected in the anterior chamber (AC) at 11 days and leukocyte recruitment continued thereafter. Polymorphonuclear neutrophils (PMN) were the predominant cell type in the AC, whereas macrophages/ monocytes and lymphocytes were predominant in the retina/subretinal space at 17 days. Peak gene expression of macrophage inflammatory protein (MIP)-1a, MIP-1ß, and MIP-2 and interferon- ?-inducible protein of 10kd (IP-10) was detected in I/CB on day 11, whereas peak expression of RANTES and eotaxin was observed at 17 days. Conclusions. Early I/CB peak expression of mRNA for MIP-2 followed by PMN recruitment into the AC, suggests that PMN may play an important role in EAU pathogenesis.

Nitroxide stable radical suppresses autoimmune uveitis in rats

Free radicals have been implicated in the pathogenesis of experimental autoimmune uveoretinitis (EAU). Nitroxides are stable radicals with a superoxide-dismutase-mimicking activity, which exert an anti-inflammatory effect in various animal models of oxidative damage and inflammation, such as experimental colitis and head trauma. We examined the use of the SOD mimic nitroxide 4-hydroxy-2,2,6,6,-tetramethylpiperidine-1-N-oxyl (TPL) to suppress EAU. Adult male Lewis rats were immunized with 125 μg/rat synthetic human retinal S-Ag, emulsified with Freund’s adjuvant. Intravenous pertussis toxin was simultaneously injected. Beginning on Day 6, rats were injected with a daily intraperitoneal dose of 35, 175 or 350 μmol/rat of the nitroxide TPL. Control rats received intraperitoneal normal saline. The animals were examined daily, and on the 19th day the eyes were enucleated. Aqueous protein concentrations and retinal lipid peroxidation product levels (ketodienes and conjugated dienes) were determined. Histological sections were stained and examined microscopically. TPL was found to penetrate the aqueous humor readily. Beginning on day 12, rats developed a severe pan-uveitis. Rats in the treatment group had a lower mean clinical and histological score than that of controls. Levels of aqueous humor protein, retinal conjugated diens and ketodiens were all significantly lower in the treatment group. This effect was more pronounced with the lower TPL concentration. We conclude that TPL reduces clinical, biochemical and histopathological severity of S-Ag induced EAU in Lewis rats. This effect is probably mediated by removal of superoxide radicals, but other mechanisms may also be involved.

Intraocular cytokine quantification of experimental autoimmune uveoretinitis in rats

Elevations of inflammatory cytokines have been implicated in the pathogenesis of experimental autoimmune uveoretinitis (EAU) in rats, although such analysis has relied on indirect methods of assessment such as measurement of mRNA content. In this study, we examined the feasibility of directly measuring cytokine concentrations in intraocular extracts prepared by ultrasonic disruption. Cytokines were measured by ELISA in eyes from EAU-induced Lewis rats immunized with interphotoreceptor retinoid-binding protein (IRBP), and compared to eyes from rats immunized with adjuvant only and from normal rats. Interferon-? (IFN-?), tumor necrosis factor-a (TNF-a), interleukin-2 (IL-2), interleukin-4 (IL-4), and interleukin-10 (IL-10) were detectable in EAU eyes at near peak inflammation, with IFN-? achieving the highest mean concentration (331 pg/ml). In eyes from rats immunized with adjuvant only and in normal eyes, IFN-?, TNF-a, and IL-10 were nondetectable. IL-2 and IL-4 were detected at significantly lower mean concentrations (32.3 pg/ml and 69.4 pg/ml, respectively) compared to EAU eyes (217 pg/ml and 230 pg/ml, respectively); IL-4 was also detected in eyes from rats immunized with adjuvant alone (141 pg/ml). Thus, a direct method of measuring intraocular cytokine concentrations was successfully applied to reveal an elevation of IFN-?, TNF-a, IL-2, IL-4, and IL-10 in EAU eyes from rats immunized with IRBP, compared to rats immunized with adjuvant alone and to normal rats. These cytokine elevations reflect the local intraocular environment near peak inflammation, and suggest an important role for these cytokines in the mechanisms of onset and resolution of EAU in rats.

Nitric oxide accelerates the onset and increases the severity of experimental autoimmune uveoretinitis through an IFN-gamma-dependent mechanism.

The production of large amounts of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) has been described as a double-edged sword eliciting pro- or anti-inflammatory effects in different immune situations. Our aim, therefore, was to investigate its role in experimental autoimmune uveoretinitis (EAU), a model of ocular inflammation, induced in the Lewis rat following a single footpad injection of retinal Ags. iNOS enzyme was not detected in the normal Lewis rat eye, but was strongly expressed by infiltrating ED1+ macrophages during the acute inflammatory stages of EAU. Treating immunized animals with L-arginine increased urinary NO metabolite (NOx) levels, accelerated the inflammatory response, and increased disease severity, whereas treatment with the NOS inhibitor, N(G)-nitro-L-arginine methyl ester, reduced NOx excretion, delayed the onset, and reduced the clinical signs of EAU. Reverse transcription-PCR analysis of ocular tissue from untreated and treated animals detected iNOS mRNA at all stages of disease, and expression was up-regulated during peak disease. L-arginine treatment enhanced cytokine mRNA expression, particularly of IFN-gamma, which was detected earlier than in control animals, corresponding with the more rapid onset of disease and increased disease severity observed in this group. N(G)-nitro-L-arginine methyl ester had little or no effect on iNOS or inflammatory cytokine mRNA expression. These results suggest NO is central to the pathogenesis of EAU and highlight the importance of the macrophage as an effector cell in what is considered a CD4+ T cell-dependent disease. Furthermore, this study demonstrates the therapeutic potential of NOS inhibitors in the treatment of inflammatory and autoimmune mediated disease.

Usage of TCR Vγ2+T Lymphocytes in Experimental Autoimmune Uveoretinitis

Experimental autoimmune uveoretinitis (EAU) is a T cell mediated autoimmune disease that serves as a model of human intraocular inflammatory disease (uveitis). It is initiated in susceptible animals by immunization with retinal antigens, such as interphotoreceptor retinoid binding protein (IRBP) and S-Antigen (SAg) or by adoptive transfer of ocular Ag-specific uveitogenic T cells. Previous studies of T cell receptor (TCR) usage by uveitogenic T cells have implicated Vβ8(+) -expressing T cells in the pathogenesis of EAU. Here, the authors have analyzed the TCR Vγ repertoire in the retinas of Lewis rats with and without EAU as well as the repertoire of several SAg- or IRBP-specific T cell lines. They detected Vγ2 transcripts in all four pathogenic lines and in the retinas of Lewis rats with EAU but not in the two non-pathogenic lines nor in the retinas of naive rats. Vγ7 transcripts were detected in RNAs obtained from the retina, regardless of whether the rat had EAU or not. However, the authors could not detect Vγ4, Vγ5 or Vγ6 TCR transcripts in any of the samples analyzed. Taken together, their data suggests a correlation between recruitment of Vγ2(+) T cells and EAU pathogenesis.

Retinal antigen-specific T cells mediate experimental autoimmune uveoretinitis (EAU) in PVG rat a model for tracking antigen-specific CD4+T cells in the inflamed eye

Experimental autoimmune uveoretinitis (EAU) is a CD(4)(+) T cell mediated organ-specific model of autoimmune disease and is considered a good model of posterior uveitis in man. Previously it has been shown that EAU may be induced in Lewis rats by adoptive transfer of small numbers of retinal antigen-specific CD(4)(+) T cell lines where recruitment of naive T cells is integral to the pathogenesis of uveitis. In order to assess the role of antigen-specific CD(4)(+) T cells in EAU, a model of passively induced EAU has been developed in which retinal extract-specific T cell lines were generated from lymph nodes of immunised PVG-RT(7)(b) rats and maintained with alternating cycles of stimulation with retinal extract presented on syngeneic accessory cells and proliferation in IL-2 rich media. The antigen-specific cell line can be categorised phenotypically by the CD(4)(+) IL-2R(+) OX(42)-OX8- cell surface expression. All cells expressed on their cell surface RT7.2 allotype of CD(45) antigen specific for PVG-RT(7)(b) strain, so that when EAU was induced by adoptive transfer with as little as 5X10(6) cells to PVG-RT(7)(a) recipients, antigen-specific cells of donor allotype (CD(4)(+) RT(7.2)(+)) may be tracked in the recipient (RT(7.1)(+) allotype). This preliminary report describes the isolation of antigen-specific (donor) T cells from the retina in early stages of passively-induced EAU, a model which can now be adopted to investigate the role different populations of cells play in the pathogenesis of EAU.

American Uveitis Society Meeting, May 13,1995 Fort Lauderdale, FL, USA

1 Confirmation of Bartonella henselae as the cause of cat scratch related acute neuroretinitis and prospective observation to its response to oral doxycycline and rifampin. Reed B, Smith R, Dolan M, Wong M, Scales D, Department of Ophthalmology & Infectious Disease, Wilford Hall Medical Center, Lackland AFB, TX, USA. 2 Recurrence rate of CMV retinitis in patients following pars plana vitrectomy and silicone oil injection. Marx JL, Thach AB, Reingold W, Terry B, Rao NA, Chong LP. Doheny Eye Institute, Los Angeles, CA, USA. 3 A PCR based assay for the diagnosis of AIDS related VZV retinitis. Margolis T, Short G, Schwartz D, Irvine A, Martin D, Francis I. Proctor Foundation, San Francisco, CA, USA. 4 Presumptive ocular sarcoidosis. Dodds EM, Lowder CY, Meisler DM. Division of Ophthalmology, Cleveland, OH, USA. 5 Prevalence of uveitis in an outpatient juvenile arthritis clinic. Akduman L, Tychsen L, Kaplan HJ, Washington University, St. Louis, MO, USA. 6 The role of choroidal dendritic cells in the pathogenesis of experimental autoimmune uveoretinitis. Choudhury A, Padhye NS, Caspi RR, Bowers WE, University of South Carolina School of Medicine, Columbia, S.C. and The National Eye Institute, Bethesda, MD, USA.

Choroidal mast cell dynamics during experimental autoimmune uveoretinitis in rat strains of differing susceptibility

Choroidal mast cells have been implicated in the pathogenesis of experimental autoimmune uveoretinitis (EAU). The aim of the present study was to examine the dynamics of choroidal mast cells during the course of EAU in rat strains of varying susceptibility. Histochemical staining showed choroidal mast cell degranulation in Lewis rats, a highly susceptible strain, commenced nine days post-immunisation, and peaked at day 11, at which time the percentage of degranulated choroidal mast cells (32. 5± 4%) was significantly higher than controls (15. 3 ± 3%; p <0.05). At day 14, mean choroidal mast cell density was significantly reduced (from 23. 6 ± 1/mm(2) tot 16. 2 ± 2/mm(2); p<0.05) and early signs of choroidal mast cell regeneration were evident. Immunisation of PVG/C (moderate susceptibility) and Brown Norway (very low susceptibility) rats produced a similar pattern of morphological changes. Onset of clinical signs in Lewis rats, which possess approximately 1100 to 1800 choroidal mast cells per eye, occurred one day following commencement of choroidal mast cell degranulation but prior to the peak of degranulation. However, in PVG/C and Brown Norway rats, which possess only approximately 70 and 110 choroidal mast cells per eye respectively, onset of disease was not temporally linked to commencement of degranulation. Production of antigen-specific IgE during the course of EAU was extremely low in all three strains. These results indicate that choroidal mast cells may be important in the pathogenesis of EAU in Lewis rats but not in PVG/C or Brown Norway rats and that non-IgE mediated degranulation may play a role in disease induction.

The blood-retinal barrier in experimental autoimmune uveoretinitis (EAU): a review

The blood-retinal barrier (BRB) is believed to play an important part in the pathogenesis of experimental autoimmune uveoretinitis (EAU). Central to the disease process is the recruitment of inflammatory cells from the circulation, a mechanism that is controlled in part by the BRB. As the disease progresses the BRB becomes disrupted first to small and then to large molecular weight tracers. In these two respects EAU shares many similarities with experimental autoimmune encephalomyelitis (EAE) in which there is dysfunction of the blood-brain barrier (BBB). In EAU, however, the differential roles played by the two barrier sites that comprise the BRB are not clear although some evidence would suggest that it is the retinal endothelium that is initially involved. BRB breakdown in EAU has been found to occur concomitantly with lymphocyte infiltration by mechanisms that remain to be elucidated.

Prevention of experimental autoimmune uveoretinitis by active immunization with autoantigen‐specific monoclonal antibodies

Preimmunization of Lewis rats with anti-S antigen (S-Ag) monoclonal antibodies (mAb) led to protection against experimental autoimmune uveoretinitis (EAU) induced by this retinal autoantigen. High titers of anti-idiotypic (anti-Id) antibodies were raised against three mouse mAb, S2D2 (IgG2b), S6H8 (IgG2a) and S7D6 (IgG1), directed at S-Ag. An almost complete prevention was observed in S2D2 mAb-immunized animals while a partial protection was achieved with S6H8 and S7D6 mAb. No detectable anti-Id antibody nor disease prevention was observed in rats immunized with the mAb S9E2 (IgG2a) which only recognizes bovine and sheep S-Ag, or with control mAb of the same isotypes irrelevant to S-Ag. The mAb treatment did not modify the level of the whole polyclonal antibody response to S-Ag. These results suggest an important role in the pathogenesis of EAU for the epitopes recognized by S2D2-S6H8 and S7D6 in the S-Ag molecule. The success of anti-Id immunization for autoimmune disease suppression may depend on the identification of relevant epitopes.