Amelioration of experimental autoimmune uveoretinitis by pretreatment with a pathogenic peptide in liposome and anti-CD40 ligand monoclonal antibody

Involvement of Angiopoietin 2 and vascular endothelial growth factor in uveitis

PURPOSE

Angiopoietin (Ang) 2 is released from vascular endothelial cells by the stimulation of vascular endothelial growth factor (VEGF)A. Ang2 increases the expression of leukocyte adhesion molecules on endothelial cells via nuclear factor κB. The aim of this study was to evaluate the effects of Ang2 and VEGFA on ocular autoimmune inflammation.

METHODS

We measured the concentrations of Ang2 and VEGFA in vitreous samples among patients with uveitis. Vitreous samples were collected from 16 patients with idiopathic uveitis (uveitis group) and 16 patients with non-inflammatory eye disease (control group). Experimental autoimmune uveoretinitis (EAU) was induced in B10.BR mice with a human interphotoreceptor retinoid-binding protein-derived peptide. The retinochoroidal tissues of the EAU mice were removed, and the mRNA levels of Ang2 and VEGFA were examined. EAU mice treated with anti-Ang2, anti-VEGFA, a combination of anti-Ang2 and anti-VEGFA, anti-Ang2/VEGFA bispecific, or IgG control antibodies were clinically and histopathologically evaluated.

RESULTS

The protein levels of Ang2 and VEGFA were significantly higher in the vitreous samples of patients with uveitis than in controls (P<0.05). The retinochoroidal mRNA levels of Ang2 and VEGFA were significantly upregulated in EAU mice compared to controls (n = 6, P<0.05). Although there was no significant difference, treatment with anti-VEGFA antibody reduced the clinical and histopathological scores. However, treatment with anti-Ang2 antibody reduced the clinical and histopathological scores (n = 18-20, P<0.05). Furthermore, these scores were further decreased when treated by inhibiting both Ang2 and VEGFA.

CONCLUSIONS

Based on these results, VEGFA and Ang2 were shown to be upregulated locally in the eye of both uveitis patients and models of uveitis. Dual inhibition of Ang2 and VEGFA is suggested to be a new therapeutic strategy for uveitis.

Anti-CD40 monoclonal antibody ameliorates experimental autoimmune uveoretinitis in mice

OBJECTIVE

To investigate the effects of CD40 on ocular inflammation in experimental autoimmune uveoretinitis (EAU) in B10.RIII mice.

ANIMALS STUDIED

EAU-susceptible B10.RIII mice were subcutaneously immunized with interphotoreceptor retinoid-binding protein (IRBP) 161-180 in complete Freund's adjuvant and evaluated clinically and pathologically on days 7, 14, 21, 28, and 35 postimmunization. Anti-CD40 antibody was intraperitoneally injected into mice every other day from days 7 to 14 postimmunization. Phosphate-buffered saline (PBS)-injected EAU mice were used as the controls.

PROCEDURES

The frequencies of CD11c⁺ CD40⁺ dendritic cells (DCs), CD11c⁺ MHC-II⁺ DCs, and CD11c⁺ CD40⁺ MHC-II⁺ DCs in splenocytes were evaluated by flow cytometry on days 0, 7, 14, and 21 after immunization. Tumor necrosis factor (TNF)-α and interleukin (IL)-6 production in CD11c⁺ DCs was assessed by ELISA. IRBP-specific lymphocyte proliferation was assessed using a modified MTT cell proliferation assay.

RESULTS

The number of CD11c⁺ CD40⁺ DCs, CD11c⁺ MHC-II⁺ DCs, and CD11c⁺ CD40⁺ MHC-II⁺ DCs increased at the onset of EAU, peaked at the height of disease severity, and was sustained at a high level until day 21. Treatment with anti-CD40 antibody significantly alleviated clinical and pathological activities related to EAU. Compared with the control mice, antibody-treated EAU mice showed few CD11c⁺ CD40⁺ DC and CD11c⁺ CD40⁺ MHC-II⁺ DC frequencies in splenocytes. The anti-CD40 antibody significantly suppressed IRBP-specific lymphocyte proliferation and TNF-α and IL-6 production by DCs in EAU mice.

CONCLUSIONS

The increased expression of CD40 and major histocompatibility complex (MHC) class II molecules in the splenocytes of EAU mice were correlated with inflammatory activity. Anti-CD40 treatment can significantly attenuate EAU activity by inhibiting systemic IRBP-specific immune responses.

Attenuation of experimental autoimmune uveoretinitis in mice by IKKβ inhibitor IMD-0354

Uveitis is a sight-threatening intraocular inflammatory disease that accounts for almost 10% of blindness worldwide. NF-κB signaling plays pivotal roles in inflammatory diseases. We have reported that IMD-0354, which inhibits NF-κB signaling via selective blockade of IKK-β, suppresses inflammation in several ocular disease models. Here, we examined the therapeutic effect of IMD-0354 in an experimental autoimmune uveoretinitis (EAU) model, a well-established animal model for endogenous uveitis in humans. Systemic administration of IMD-0354 significantly suppressed the clinical and histological severity, inflammatory edema, and the translocation of NF-κB p65 into the nucleus of retinas in EAU mice. Furthermore, IMD-0354 treatment significantly inhibited the levels of several Th1/Th17-mediated pro-inflammatory cytokines in vitro. Our current data demonstrate that inhibition of IKKβ with IMD-0354 ameliorates inflammatory responses in the mouse EAU model, suggesting that IMD-0354 may be a promising therapeutic agent for human endogenous uveitis.

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.

Increased CD40+ Fibrocytes in Patients With Idiopathic Orbital Inflammation

OBJECTIVE

To investigate the phenotypic and functional characteristics of peripheral and tissue-infiltrating stem cells called fibrocytes in patients with idiopathic orbital inflammation (IOI).

METHODS

Seven patients with IOI were studied. In the 3 patients requiring orbital biopsy, fibrocytes were identified in orbital tissue from patients with IOI compared with healthy controls using immunohistochemistry. Fibrocytes from the peripheral blood of all 7 patients and controls were quantified and phenotyped by flow cytometry and immunofluorescence for expression of CD34, alpha smooth muscle actin, CD40, and collagen 1. Quantitation of CD40-mediated interleukin-6 (IL-6) production was measured using enzyme-linked immunosorbent assay.

RESULTS

Orbital biopsy specimens from patients with IOI demonstrate tissue infiltration by fibrocytes (n = 3). Fibrocytes are present in the peripheral blood of IOI patients (n = 7) but are scarce in healthy donors (n = 19). Fibrocytes from IOI patients express substantial levels of CD40, and ligation of CD40 increases IL-6 expression.

CONCLUSIONS

Fibrocytes are present in the peripheral blood and orbital tissues of patients with IOI and constitutively express CD40 and express IL-6 in response to ligation. This site-specific predilection of CD34(+) fibrocytes to sites of orbital inflammation and fibrosis may suggest a role in IOI. Moreover, CD40-mediated activation cytokine production may contribute to the proinflammatory and profibrotic features of IOI and may provide a mechanism for future targeted therapy.

Pivotal roles of T-helper 17-related cytokines, IL-17, IL-22, and IL-23, in inflammatory diseases

T-helper 17 (Th17) cells are characterized by producing interleukin-17 (IL-17, also called IL-17A), IL-17F, IL-21, and IL-22 and potentially TNF- α and IL-6 upon certain stimulation. IL-23, which promotes Th17 cell development, as well as IL-17 and IL-22 produced by the Th17 cells plays essential roles in various inflammatory diseases, such as experimental autoimmune encephalomyelitis, rheumatoid arthritis, colitis, and Concanavalin A-induced hepatitis. In this review, we summarize the characteristics of the functional role of Th17 cells, with particular focus on the Th17 cell-related cytokines such as IL-17, IL-22, and IL-23, in mouse models and human inflammatory 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.

Aminoimidazole carboxamide ribonucleotide ameliorates experimental autoimmune uveitis

PURPOSE

To investigate the anti-inflammatory effect of an adenosine monophosphate (AMP) analog, aminoimidazole carboxamide ribonucleotide (AICAR), in experimental autoimmune uveoretinitis (EAU).

METHODS

C57BL/6 mice were injected daily with AICAR (200 mg/kg, intraperitoneally [IP]) from day 0, the day of interphotoreceptor retinoid-binding protein (IRBP) immunization, until day 21. The severity of uveitis was assessed clinically and histopathologically. T-cell proliferation and cytokine production of IFN-γ, IL-17, and IL-10 in response to IRBP stimulation were determined. In addition, regulatory T-cell (Treg) populations were measured. Co-stimulatory molecule expression (CD40, 80, 86, and I-Ab) on dendritic cells (DCs) in EAU and on bone marrow-derived dendritic cells (BMDCs) treated with AICAR was measured.

RESULTS

AICAR treatment significantly reduced clinical and histologic severity of EAU as well as ocular cytokine production. An anti-inflammatory effect associated with the inhibition of T-cell proliferation and Th1 and Th17 cytokine production was observed. Increases in the Th2 response and Treg population were not observed with AICAR treatment. AICAR did significantly inhibit BMDC maturation by reducing co-stimulatory molecule expression.

CONCLUSIONS

AICAR attenuates EAU by preventing generation of Ag-specific Th1 and Th17 cells. Impaired DC maturation may be an underlying mechanism for this anti-inflammatory effect observed with AICAR.

Prevention of experimental autoimmune uveoretinitis by blockade of osteopontin with small interfering RNA

Osteopontin (OPN) is elevated during the progression of experimental autoimmune uveoretinitis (EAU) in C57BL/6 (B6) mice. Furthermore, EAU symptoms are ameliorated in OPN knockout mice or in B6 mice treated with anti-OPN antibody (M5). Recently, OPN has been shown to promote the Th1 response not only in the extracellular space as a secretory protein but also in cytosol as a signaling component. Thus, we attempted to reduce OPN in both compartments by using a small interfering RNA (siRNA) targeting the OPN coding sequence (OPN-siRNA). EAU was induced in B6 mice by immunization with human interphotoreceptor retinoid-binding protein (hIRBP) peptide sequence 1-20. The OPN- or control-siRNA was administered with hydrodynamic methods 24 h before and simultaneously with immunization (prevention regimen). When plasma OPN levels were quantified following siRNA administration with the prevention regimen, the level in the OPN-siRNA-treated group was significantly lower than that in the control-siRNA-treated group. Accordingly, the clinical and histopathological scores of EAU were significantly reduced in B6 mice when siRNA caused OPN blockade. Furthermore, TNF-alpha, IFN-gamma, IL-2, GM-CSF and IL-17 levels in the culture supernatants were markedly suppressed in the OPN-siRNA-treated group, whereas the proliferative responses of T lymphocytes from regional lymph nodes against immunogenic peptides was not significantly reduced. On the other hand, the protection was not significant if the mice received the OPN-siRNA treatment on day 7 and day 8 after immunization when the clinical symptoms appeared overt (reversal regimen). Our results suggest that OPN blockade with OPN-siRNA can be an alternative choice for the usage of anti-OPN antibody and controlling uveoretinitis in the preventive regimen.

Eye-concentrated distribution of dexamethasone carried by sugar-chain modified liposome in experimental autoimmune uveoretinitis mice

Corticosteroid is generally accepted as a standard therapeutic agent for active inflammatory (and) autoimmune eye diseases. In an attempt to develop a system to deliver corticosteroid most efficiently to the target eye, a sialyl-Lewis X (sLe(x))-conjugated liposome was adopted as a candidate for a carrier of dexamethasone (Dexa) and tissue distribution of intravenous Dexa with the modified liposome as well as Dexa alone as control was studied in normal and experimental autoimmune uveoretinitis (EAU) mice. Intravenous Dexa (1 mg) was widely distributed in all the tissues (eye, brain, heart, lung, liver, kidney, spleen and intestine) examined in similar manner in both mice and Dexa concentration was lowest in the eye except the brain. The tissue concentrations of Dexa in EAU group were all significantly lower than those in the corresponding tissues in normal group. Intravenous Dexa (2 microg) in the modified liposome was almost concentrated to the eye in EAU mice, reaching 13.84 ng/mg tissue in contrast to 2.34 ng/mg tissue in Dexa (1 mg) alone administered EAU mice. In normal mice, Dexa was undetectable in any tissues examined and thus the effect of the modified liposome was not observed. The result supported the potentiality of sLe(x)-conjugated liposome for target-delivering of corticosteroid to inflamed eye.

Osteopontin Aggravates Experimental Autoimmune Uveoretinitis in Mice

Human endogenous uveitis is a common sight-threatening intraocular inflammatory disease and has been studied extensively using a murine model of experimental autoimmune uveoretinitis (EAU). It is possibly mediated by Th1 immune responses. In the present study, we investigated the role of osteopontin (OPN), a protein with pleiotropic functions that contributes to the development of Th1 cell-mediated immunity. Accompanying EAU progression, OPN was elevated in wild-type (WT) mice that had been immunized with human interphotoreceptor retinoid-binding protein (hIRBP) peptide 1-20. OPN-deficient (OPN-/-) mice showed milder EAU progression in clinical and histopathological scores compared with those of WT mice. The T cells from hIRBP-immunized OPN-/- mice exhibited reduced Ag-specific proliferation and proinflammatory cytokine (TNF-alpha and IFN-gamma) production compared with those of WT T cells. When hIRBP-immunized WT mice were administered M5 Ab reacting to SLAYGLR sequence, a cryptic binding site to integrins within OPN, EAU development was significantly ameliorated. T cells from hIRBP-immunized WT mice showed significantly reduced proliferative responses and proinflammatory cytokine production upon stimulation with hIRBP peptide in the presence of M5 Ab in the culture. Our present results demonstrate that OPN may represent a novel therapeutic target to control uveoretinitis.

The role of the ICOS/B7RP-1 T cell costimulatory pathway in murine experimental autoimmune uveoretinitis

ICOS/B7RP-1 is a new member of the CD28/B7 family of costimulatory molecules and plays differential roles in autoimmune diseases. In this study, we examined the role of ICOS/B7RP-1 pathway in the pathogenesis of mouse experimental autoimmune uveoretinitis (EAU), an animal model of human autoimmune uveitis. ICOS expression was found on infiltrating CD4+ T cells in the region of the retina in EAU-induced mice. The anti-B7RP-1 monoclonal antibody (mAb)-treated or ICOS-deficient mice showed a substantial reduction of disease scores. Blockade of ICOS/B7RP-1 interaction during the effector phase ameliorated the disease, whereas its blockade during the induction phase exhibited no significant effect. Moreover, administration of anti-B7RP-1 mAb effectively ameliorated the disease induced by adoptive transfer of pathogenic T cells. The anti-B7RP-1 mAb treatment inhibited the expansion and/or effector function of pathogenic T cells, given that proliferative response and IFN-gamma production by lymph node cells were reduced upon restimulation with the antigen peptide in vitro. These results suggest that the ICOS/B7RP-1 interaction plays a critical role in the pathogenesis of uveitis. We also indicated that ICOS-mediated costimulation plays differential roles in EAU and experimental autoimmune encephalomyelitis, which is also a Th1 disease induced in the same manner as EAU.

Induction of dominant tolerance using monoclonal antibodies

Monoclonal antibodies (MAb) have been shown to be effective in inducing immune tolerance in transplantation and autoimmunity. Several different MAb have tolerogenic properties and their effect has been studied in a range of experimental animal models and, in some cases, in clinical trials. The tolerant state seems to be maintained by CD4+ regulatory T cells (Treg), induced in the periphery, capable of suppressing other T cells specific for the same antigens or antigens presented by the same antigen presenting cells. Furthermore, following the initial induction of Treg cells under MAb treatment, Treg cells themselves can maintain the tolerant state in a dominant way in the absence of the therapeutic MAb or other immunosuppressive agents, and are able to recruit other T cells into the regulatory pool--a process named infectious tolerance.

Allograft inflammatory factor-1 regulates trinitrobenzene sulphonic acid-induced colitis

The expression of allograft inflammatory factor-1 (AIF-1) in 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced colitis, a model for T helper 1 (Th1) type disease, was investigated in BALB/c mice. The AIF-1 expression was significantly increased in the colitis lesion compared to that in the normal colon. We then prepared AIF-1 transgenic mice (Tgm) with the BALB/c background that express high levels of AIF-1 in lymphoid tissues and the colon. When AIF-1 Tgm were administrated TNBS, the TNBS-induced colitis was ameliorated compared with that in non-transgenic littermates. The amelioration of colitis was associated with the low expression of interleukin-1beta in the colon. The present findings suggest that AIF-1 regulates Th1-type inflammatory responses.

Normal Th1 development following long-term therapeutic blockade of CD154-CD40 in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a Th1-mediated demyelinating disease of the CNS with similarities to multiple sclerosis. We and others have shown that a short-term course of anti-CD154 mAb treatment to block CD154-CD40 interactions can be used to prevent or even treat ongoing PLP139-151-induced relapsing EAE. However, little is known of the long-term effects of CD154 blockade on the development of antigen-specific T cell function. Here, we show that short-term treatment with anti-CD154 at the time of PLP139-151/CFA immunization inhibits clinical disease for up to 100 days after immunization. At this point, comparable numbers of Th1 cells are observed in anti-CD154 and control Ig-treated mice, as assessed by antigen-specific ELISPOT assays. Thus, the long-term Th1/Th2 balance is largely unaffected. Inflammatory responses are diminished in anti-CD154-treated mice, as indicated by reduced in vivo delayed-type hypersensitivity and reduced levels of splenic IFN-gamma secretion in vitro. However, upon adoptive transfer of T cells isolated from the spleens of anti-CD154-treated mice, these cells contributed as effectively to clinical disease as those obtained from control-treated mice. Thus, anti-CD154 therapy leads to long-term therapeutic efficacy without exerting a long-term influence on Th1 development.

Vaccination, prevention, and treatment of experimental autoimmune neuritis (EAN) by an oligomerized T cell epitope

Using a polypeptide oligomer harboring 16 repeats of the neuritogenic epitope (aa 58-73) of myelin P2 protein separated by spacers, enhancement of the immune response to the P2 protein, an important neuritogenic autoantigen in experimental autoimmune neuritis (EAN), was attempted. In contrast to a previous study with PLP-16-mer antigen-specific response of T cells was attenuated at all doses examined to a variable degree. Treatment of Lewis rats with the P2-16-mer up to 2 months before immunization with P2(53-78) (vaccination) or after immunization but before appearance of disease (prevention) had a strong tolerizing effect against the induction of EAN on immunization with P2(53-78). Moreover, rats injected with 200 microg of the P2-16-mer i.v. on day 11 after disease induction, at which time the initial signs of disease had appeared, were almost completely protected against progression of clinical disease, whereas animals treated with the same amount of monomeric control peptide developed severe disease (treatment). Similar results were obtained by i.v. treatment of adoptive-transfer EAN with the P2-16-mer. The lack of clinical signs of disease after 16-mer therapy could be correlated with a reduced proliferative response of P2(53-78)-specific lymph node cells. The frequency of apoptotic T cells in sciatic nerve or in lymph node cells, however, was not increased by the 16-mer treatment, suggesting that induction of anergy or other forms of peripheral tolerance may be responsible for the effect. Thus, the oligomerized P2 peptide antigen was highly effective in all three treatment modalities examined in this specific autoreactive T cell-mediated immune response.

Amelioration of experimental autoimmune encephalomyelitis in C57BL/6 mice by an agonist of peroxisome proliferator-activated receptor-gamma

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma), a member of the nuclear hormone receptor superfamily, plays a critical role in adipocyte differentiation and glucose homeostasis. It has been implicated that PPAR-gamma functions as a regulator of cellular proliferation and inflammatory responses. In the present study, we examined whether troglitazone, a selective PPAR-gamma agonists, ameliorated experimental autoimmune encephalomyelitis (EAE) induced by administration of myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 in C57BL/6 mice. We found that troglitazone attenuated the inflammation and decreased the clinical symptoms. It was suggested that the amelioration was attributed to the attenuation of pro-inflammatory cytokine gene expressions.