Prevention of experimental autoimmune uveoretinitis by monoclonal antibody to interleukin-12

Serum Th1 and Th17 related cytokines and autoantibodies in patients with Posner-Schlossman syndrome

Posner-Schlossman syndrome (PSS) shares some clinical features with uveitis and open angle glaucoma. Cytokines and autoantibodies have been associated with uveitis and open angle glaucoma. However, the role of serum cytokines and autoantibodies in the pathogenesis of PSS remains unknown. This study aimed to evaluate the associations of type 1 T helper (Th1) and Th17 related cytokines and autoantibodies with PSS. Peripheral blood serum samples were collected from 81 patients with PSS and 97 gender- and age-matched healthy blood donors. Th1 and Th17 related cytokines, including interleukin-1β (IL-1β), IL-12, tumor necrosis factor-α (TNF-α), interferon- γ (IFN-γ), IL-6 and IL-17, and glucose-6-phosphate isomerase (GPI) were determined by double antibody sandwich ELISA. Anti-nuclear antibody (ANA), anti-keratin antibody (AKA) and anti-neutrophil cytoplasmic antibody (ANCA) were detected by indirect immunofluorescence assay. Anti-cardiolipin antibody (ACA)-IgG, ACA-IgM, ACA-IgA, anti-double stranded DNA (anti-dsDNA) and anti-cyclic citrullinated peptide antibody (anti-CCP) were detected by indirect ELISA. Serum levels of IL-1β, IL-12 and IL-6 in PSS patients were significantly lower than those in controls (P < 0.003), and these associations survived the Bonferroni correction (Pc < 0.018). There was no significant difference in serum levels of TNF-α, IFN-γ and IL-17 between the PSS and control groups (Pc > 0.12). Positive rate of serum anti-dsDNA in PSS patients was significantly higher than that in the control group (P = 0.002, Pc = 0.018), while positive rates of serum ANA, AKA, ANCA, ACA-IgG, ACA-IgM, ACA-IgA, GPI and anti-CCP in the PSS group were not significantly different from those in the control group (Pc > 0.09). These results suggest that anti-dsDNA may contribute to the pathogenesis of PSS, while Th1 and Th17 related cytokines and other autoantibodies may not be major contributors to PSS.

The Role of IFN-alpha in Experimental and Clinical Uveitis

PURPOSE

IFN-α is the only treatment capable of inducing long-term remission in some patients with ocular Behçet's disease. In this review, we focus on immune mechanisms of IFN-α in animal models and patients and compare the outcome of different clinical studies.

METHODS

Review of literature using PubMed and Google and original data from rat models with monophasic/chronic or relapsing experimental autoimmune uveitis treated with IFN-α.

RESULTS

The role of IFN-α and its effect on various cell types were investigated, in some cases with contradictory results. Some patients respond very well to IFN-α treatment, while others are non-responders, which was reflected in the uveitis rat models: relapsing uveitis was ameliorated, the monophasic/chronic disease even aggravated.

CONCLUSIONS

Despite intensive investigations in patients and animal models, the immune mechanisms explaining the therapeutic effect of IFN-α in ocular Behçet's disease are not yet fully understood and need further investigation.

Daphnetin Alleviates Experimental Autoimmune Encephalomyelitis via Regulating Dendritic Cell Activity

AIMS

Daphnetin, a coumarin derivative extracted from Daphne odora var. marginata, has been reported to have antiinflammatory and immunosuppressive properties. Our previous study indicated that it was able to remarkably suppress the neuroinflammation and suggested its potential application in treating neuroinflammatory diseases. Multiple sclerosis (MS), a Th cell-mediated autoimmune disease, is the most common inflammatory demyelinating disease of the central nervous system (CNS). We examined whether daphnetin treatment can protect mice against experimental autoimmune encephalomyelitis (EAE), an animal model for MS.

METHODS

To assess the effect of daphnetin in neuroinflammatory diseases, the EAE mice were established and treated with daphnetin at 8 mg/kg for 28 days. The severity of neuroinflammation and demyelination in the spinal cords was examined histopathologically. Infiltration of CD4(+) T cells into the CNS was assessed by immunohistochemistry, and the cytokine production was determined by ELISA. Meanwhile, the effect of daphnetin on the activity of dendritic cells (DCs) was evaluated, as assessed by DCs' capability to express surface markers, secrete cytokines, and activate naïve CD4(+) T cells. Furthermore, we explored the molecular mechanisms whereby DAPH regulated DCs' activity and thereby CD4(+) T cell responses.

RESULTS

The administration of daphnetin markedly alleviated the clinical symptoms of EAE and reduced the CNS inflammation and demyelination in experimental mice. Th1 and Th17 cell responses were profoundly repressed in daphnetin-treated EAE mice. Mechanistically, daphnetin treatment significantly repressed the activation, maturation, and antigen-presenting capability of DCs. NF-κB signaling was significantly reduced in daphnetin-treated DCs, along with a concomitant induction of heme oxygenase-1, a negative regulator of inflammatory signaling.

CONCLUSIONS

Our findings for the first time demonstrate the property of daphnetin in regulating DCs' function and subsequently Th development. Given the low or absent toxicity associated with daphnetin, our data may suggest a novel safe and effective approach to control autoimmune neuroinflammation.

Do Natural T Regulatory Cells become Activated to Antigen Specific T Regulatory Cells in Transplantation and in Autoimmunity?

Antigen specific T regulatory cells (T_reg) are often CD4⁺CD25⁺FoxP3⁺ T cells, with a phenotype similar to natural T_reg (nT_reg). It is assumed that nT_reg cannot develop into an antigen specific T_reg as repeated culture with IL-2 and a specific antigen does not increase the capacity or potency of nT_reg to promote immune tolerance or suppress in vitro. This has led to an assumption that antigen specific T_reg mainly develop from CD4⁺CD25⁻FoxP3⁻ T cells, by activation with antigen and TGF-β in the absence of inflammatory cytokines such as IL-6 and IL-1β. Our studies on antigen specific CD4⁺CD25⁺ T cells from animals with tolerance to an allograft, identified that the antigen specific and T_reg are dividing, and need continuous stimulation with specific antigen T cell derived cytokines. We identified that a variety of cytokines, especially IL-5 and IFN-γ but not IL-2 or IL-4 promoted survival of antigen specific CD4⁺CD25⁺FoxP3⁺ T_reg. To examine if nT_reg could be activated to antigen specific T_reg, we activated nT_reg in culture with either IL-2 or IL-4. Within 3 days, antigen specific T_reg are activated and there is induction of new cytokine receptors on these cells. Specifically nT_reg activated by IL-2 and antigen express the interferon-γ receptor (IFNGR) and IL-12p70 (IL-12Rβ2) receptor but not the IL-5 receptor (IL-5Rα). These cells were responsive to IFN-γ or IL-12p70. nT_reg activated by IL-4 and alloantigen express IL-5Rα not IFNGR or IL-12p70Rβ2 and become responsive to IL-5. These early activated antigen specific T_reg, were respectively named Ts1 and Ts2 cells, as they depend on Th1 or Th2 responses. Further culture of Ts1 cells with IL-12p70 induced Th1-like T_reg, expressing IFN-γ, and T-bet as well as FoxP3. Our studies suggest that activation of nT_reg with Th1 or Th2 responses induced separate lineages of antigen specific T_reg, that are dependent on late Th1 and Th2 cytokines, not the early cytokines IL-2 and IL-4.

Biologic agents in experimental autoimmune uveitis

Experimental uveitis models were developed in an effort to elucidate the pathogenesis of human uveitis. The therapeutic effects of numerous anti-inflammatory agents including corticosteroids and immunomodulatory agents including biologic response modifiers have been investigated in both experimental and human uveitis. Monoclonal antibodies to tumor necrosis factor alpha and anti-interleukins, among others, demonstrate efficacy and are employed in the treatment of uveitis refractory to conventional immunomodulatory agents.

Toll-like receptor 3 ligand polyinosinic:polycytidylic acid enhances autoimmune disease in a retinal autoimmunity model

Viral components can trigger autoimmunity, but the involved mechanisms remain to be elucidated. Toll-like receptor 3 (TLR3) recognizes viral double-stranded RNA (dsRNA) and appears to play an important role in this context. Our previous studies showed that signaling of TLR2, TLR3, TLR4 and TLR9 is highly redundant in the adjuvant effect needed to induce experimental autoimmune uveitis (EAU), an animal model of human autoimmune eye disease. In this study, we analyzed the effects of systemic delivery of polyinosinic:polycytidylic acid (poly(I:C)), a mimic of viral dsRNA, in the induction of EAU. We found that TLR3 agonist poly(I:C) enhanced EAU scores, DTH responses and Ag-specific T cell proliferation. In addition, Ag-specific Interleukin 17 (IL-17) and interferon gamma (IFN-γ) production by draining lymph node cells was markedly increased in the poly(I:C)-treated group. Our results suggest that activation of innate immune system mediated by TLR3 signaling pathway is of importance in the pathogenesis of virus-induced autoimmune diseases.

The potential of newer immunomodulating drugs in the treatment of uveitis: a review

Uveitis, or intraocular inflammation, remains an ongoing challenge to ophthalmologists and patients alike. In most patients, uveitis is limited to the anterior ocular structures and is readily managed with topical steroids. The inflammatory process can extend behind the lens to involve the pars plana, the vitreous cavity, the choroid and the retina. These intermediate and posterior uveitides are relatively rare but contribute disproportionately to visual morbidity and present serious diagnostic and therapeutic difficulties. Systemic steroids constitute the first line of treatment for most sight-threatening uveitides. Their long term use is limited by universal and debilitating adverse effects. Second-line, steroid-sparing agents allow a reduction in steroid dosage. Cyclosporin and azathioprine are the main steroid-sparing agents currently in use. However, these compounds are limited by a narrow therapeutic window and significant adverse effects. This paper offers a brief discussion of some of the immune mechanisms involved in the pathogenesis of uveitis and reviews categories of investigational compounds. Inhibitors of T cell function: tacrolimus (previously FK506), licensed for use in liver transplantation, and sirolimus (rapamycin) are macrolide antibiotics. Sirolimus is a functional cytokine antagonist and in vitro studies suggest it could be up to 100 times more potent than cyclosporin. Drug synergy between sirolimus and cyclosporin has been demonstrated, resulting in immunosuppression at lower drug doses and with fewer adverse effects. Nucleotide synthesis inhibitors: mycophenolate mofetil (MMF) and leflunomide. Human lymphocytes are only able to synthesise nucleic acids de novo. Having no alternative or 'salvage' pathway, they are exquisitely sensitive to interference with the de novo nucleotide synthesis enzymatic pathway. MMF is a purine synthesis inhibitor. Compared to other purine inhibitors, early data suggest that MMF is more efficacious and less toxic than azathioprine. Leflunomide is an inhibitor of pyrimidine synthesis. Monoclonal surface receptor antibodies and immunoadhesins: the IL-2 receptor is essential for clonal expansion of activated T cells; this has led to the development of anti-IL-2 receptor antibodies. Daclizumab is a genetically engineered humanised IgG1 monoclonal antibody. In conjunction with cyclosporin, it significantly reduces renal allograft rejection rates and is also showing promise in the treatment of T cell mediated autoimmune disorders. The mechanism of action of monoclonal antibodies to other pro-inflammatory cytokines such as TNFalpha and IL-12 and data from animal and human uveitis trials are also discussed. Finally, new avenues of research in immunopharmaco-modulation are mentioned.

Involvement of Th17 cells and the effect of anti-IL-6 therapy in autoimmune uveitis

OBJECTIVES

Human endogenous uveitis is one of the sight-threatening diseases associated with variety of systemic disorders, such as Behcet's disease and sarcoidosis. Recently, biosynthesized antibodies against inflammatory cytokines have been recognized to be useful to control the regional inflammation. In this study, we focused on the possibility of IL-6-based biological therapies for endogenous uveitis. We initially confirmed the significant increase of several inflammatory soluble factors including IL-6 in the vitreous fluids from refractory/chronic engogenous uveitis patients.

METHODS

To investigate the role of IL-6 in the formation of refractory ocular inflammation, we used the mouse experimental autoimmune uveitis (EAU) model. Both IL-6 and IL-23 are required for the development of IL-17-producing helper T subset (Th17) from naïve CD4(+) T cells. Results. In the EAU model, neither IL-6-deficient mice nor IL-23-deficient mice could induce Th17 cells and the EAU score was decreased in these mice in the entire time course. We also confirmed that systemic administration of anti-il-6 receptor antibody ameliorates EAU By suppressing both systemic and regional TH17 responses.

CONCLUSIONS

IL-6 is responsible for causing ocular inflammation, and it is, at least partially, due to IL-6-dependent Th17 differentiation. IL-6 may be a target for therapy of refractory endogenous uveitis in humans.

Therapeutic effect of the potent IL-12/IL-23 inhibitor STA-5326 on experimental autoimmune uveoretinitis

Introduction

The purpose of this study was to determine if oral administration of the interleukin (IL) 12/IL-23 inhibitor, STA-5326, is effective in experimental autoimmune uveoretinitis (EAU).

Methods

C57BL/6J mice were immunised with human interphotoreceptor retinoid binding protein peptide (IRBP_1–20). STA-5326 at a dose of either 5 mg/kg or 20 mg/kg, or vehicle alone, was orally administered once a day for six days a week from day 0 to day 14. Fundus examination was performed on day 14 and day 18 after immunisation. Mice were euthanased on day 18 and the eyes were enucleated for histopathological examination. In vivo-primed draining lymph node cells were stimulated with IRBP_1–20 and culture supernatant was harvested for assay of interferon (IFN)-γ and IL-17 by ELISA. Intracellular expression of IFN-γ and IL-17 in CD4⁺ T cells of cultured draining lymph node cells was assessed by flow cytometry. The level of IL-12 p40 in serum was examined in STA-5326-treated or vehicle-treated mice receiving immunisation.

Results

The level of IL-12 p40 in serum was decreased in mice treated with STA-5326. Oral administration of either 5 mg/kg or 20 mg/kg STA-5326 reduced the severity of EAU on day 14 and 18. In addition, mice treated with 20 mg/kg STA-5326 showed significantly decreased severity of EAU by histopathological analysis. Although IFN-γ production of draining lymph node cells was increased in STA-5326-treated mice by ELISA analysis, the proportion of IFN-γ-producing cells was not significantly altered. However, IL-17 production and the proportion of IL-17-producing cells were significantly reduced in STA-5326-treated mice. Furthermore, oral administration of STA-5326 during the effector phase reduced the severity of EAU.

Conclusions

These results indicate that oral administration of the IL-12/IL-23 inhibitor STA-5326 is effective in suppressing inflammation in the EAU model, and reduces the expansion of IL-17-producing cells. STA-5326 may represent a new therapeutic modality for human refractory uveitis.

Embryonic stem cells ameliorate piroxicam-induced colitis in IL10-/- KO mice

The primary objective of this work is to determine the repairing potential of murine embryonic stem cells (ES) in murine model of Crohn's disease (CD). Colitis, induced in IL10-/- KO mice using piroxicam, was associated with the increased levels of IL-12. Enhanced yellow fluorescent protein (EYFP) marked murine ES cells (R1/129) and control non-fluorescent ES cells were subjected to in vitro differentiation into intestinal epithelial cells. IL 10-/- KO mice were injected with pre-differentiated ES-YFP cells and sacrificed after 2 and 3 months. Histopathological analysis of intestines demonstrated a progressive improvement in colitis (from grade-4 to grade-1 and -0) and decreased levels of IL-12 cytokine following transplantation. Fluorescent and confocal microscopy demonstrated presence of ES-EYFP cells in the colon, small intestine, liver, and thymus tissues but none in the spleen and bone marrow. The EYFP signal was not detected in sham (non-transplanted mice with induced colitis) and control IL10-/- KO mice. Engraftment, detected at 3 months post-transplant, correlated with markedly improved grading in colon histology (grade-1 or -0) and weight gain, as well as with decreased rectal prolapses. In vitro pre-differentiated ES cells migrated and homed exclusively into the colon, small intestine, and the liver, engrafted for long term, reduced inflammation and tissue damage, and restored immune balance. These findings suggest that pre-differentiated ES cells may become alternative source of stem cell therapy for CD with dual functions i.e. regenerating damaged epithelium and restoring immune imbalance occurring in this disease.

Regulation of cytokine production during phagocytosis of apoptotic cells

Loss of self-tolerance and expansion of auto-reactive lymphocytes are the basis for autoimmunity. Apoptosis and the rapid clearance of apoptotic cells by phagocytes usually occur as coordinated processes that ensure regulated cellularity and stress response with non-pathological outcomes. Defects in clearance of apoptotic cells would contribute to the generation of self-reactive lymphocytes, which drive autoimmune disorders such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). The IL-12 family of cytokines (IL-12, IL-23, and IL-27) and IL-10 are produced by phagocytic macrophages and play critical roles in the regulation of antigen-presenting cells (APCs) and effector lymphocytes during an immune response to pathogens. Inappropriate expression of these cytokines and their dysregulated activities have been strongly implicated in the pathogenesis of several autoimmune diseases. The production of pro- and anti-inflammatory cytokines by phagocytic APCs is delicately regulated during the ingestion of apoptotic cells as part of an intrinsic mechanism to prevent inflammatory autoimmune reactions. How apoptotic cell-derived signals regulate cytokine production is poorly understood. A recent study by our group demonstrated that phagocytosis of apoptotic cells by activated macrophages results in strong inhibition of IL-12 p35 gene expression by activating a novel transcription repressor, which we named GC-binding protein (GC-BP), through tyrosine dephosphorylation. We are also beginning to understand the molecular mechanisms underlying apoptotic cell-triggered production of IL-10 by phagocytes. These studies will help to elucidate some novel immune regulatory mechanisms and explore the regulation of immune responses to autoantigens with potentials to discover new therapeutic targets for the treatment of autoimmune disorders.

Cytokines and chemokines in uveitis: is there a correlation with clinical phenotype?

Uveitis is a general term for intraocular inflammation and includes a large number of clinical phenotypes. As a group of disorders, it is responsible for 10% of all registered blind patients under the age of 65 years. Immune-mediated uveitis may be associated with a systemic disease or may be localized to the eye. The pro-inflammatory cytokines interleukin (IL)-1beta, IL-2, IL-6, interferon-gamma and tumor necrosis factor-alpha have all been detected within the ocular fluids or tissues in the inflamed eye together with others, such as IL-4, IL-5, IL-10 and transforming growth factor-beta. The chemokines IL-8, monocyte chemoattractant protein-1, macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and fractalkine are also thought to be involved in the associated inflammatory response. There have been a number of studies in recent years investigating cytokine profiles in different forms of uveitis with a view to determining what cytokines are important in the inflamed eye. This review attempts to present the current state of knowledge from in vitro and in vivo research on the inflammatory cytokines in intraocular inflammatory diseases.

An Anti-IL-12p40 Antibody Down-Regulates Type 1 Cytokines, Chemokines, and IL-12/IL-23 in Psoriasis

Psoriasis is characterized by activation of T cells with a type 1 cytokine profile. IL-12 and IL-23 produced by APCs are essential for inducing Th1 effector cells. Promising clinical results of administration of an Ab specific for the p40 subunit of IL-12 and IL-23 (anti-IL-12p40) have been reported recently. This study evaluated histological changes and mRNA expression of relevant cytokines and chemokines in psoriatic skin lesions following a single administration of anti-IL-12p40, using immunohistochemistry and real-time RT-PCR. Expression levels of type 1 cytokine (IFN-gamma) and chemokines (IL-8, IFN-gamma-inducible protein-10, and MCP-1) were significantly reduced at 2 wk posttreatment. The rapid decrease of these expression levels preceded clinical response and histologic changes. Interestingly, the level of an anti-inflammatory cytokine, IL-10, was also significantly reduced. Significant reductions in TNF-alpha levels and infiltrating T cells were observed in high responders (improvement in clinical score, > or =75% at 16 wk), but not in low responders. Of importance, the levels of APC cytokines, IL-12p40 and IL-23p19, were significantly decreased in both responder populations, with larger decreases in high responders. In addition, baseline levels of TNF-alpha significantly correlated with the clinical improvement at 16 wk, suggesting that these levels may predict therapeutic responsiveness to anti-IL-12p40. Thus, in a human Th1-mediated disease, blockade of APC cytokines by anti-IL-12p40 down-regulates expression of type 1 cytokines and chemokines that are downstream of IL-12/IL-23, and also IL-12/IL-23 themselves, with a pattern indicative of coordinated deactivation of APCs and Th1 cells.

The therapeutic potential of anti-cytokine antibodies in the treatment of chronic inflammatory disease

The outcome of inflammatory diseases is likely to be dependent upon the relative balance of pro- versus anti-inflammatory cytokines. Control of this balance through the use of anti-cytokine monoclonal antibodies (mAbs) promises to be an effective means of disease therapy. The treatment of rheumatoid arthritis (RA) or inflammatory bowel disease (IBD) with anti- tumour necrosis factor alpha (TNF-alpha) mAb has dramatically ameliorated disease symptoms, indicating that such a treatment approach can be highly successful. Similarly, based on animal studies, the use of neutralising anti-interleukin (IL)-12 mAb may prove efficacious in a number of inflammatory disorders, particularly for IBD.

Transcriptional Suppression of Interleukin-12 Gene Expression following Phagocytosis of Apoptotic Cells

Phagocytosis of apoptotic cells usually results in an anti-inflammatory state with inhibition of proinflammatory cytokines such as IL-12. How apoptotic cell-derived signals regulate IL-12 gene expression is not understood. We demonstrate that cell-cell contact with apoptotic cells is sufficient to induce profound inhibition of IL-12 production by activated macrophages. Phosphatidylserine could mimic the inhibitory effect. The inhibition does not involve autocrine or paracrine actions of IL-10 and TGF-beta. We report the identification, purification, and cloning of a novel zinc finger nuclear factor, named GC binding protein (GC-BP), that is induced following phagocytosis of apoptotic cells by macrophages or by treatment with phosphatidylserine. GC-BP selectively inhibits IL-12 p35 gene transcription by binding to its promoter in vitro and in vivo, thus decreasing IL-12 production. Blocking GC-BP by RNA interference restores IL-12 p35 transcription and IL-12 p70 synthesis. Finally, GC-BP itself undergoes functionally significant tyrosine dephosphorylation in response to apoptotic cells.

Combined cyclosporin-A /prednisone therapy of patients with active uveitis suppresses IFN-gamma production and the function of dendritic cells

In this study, we assessed the Th1/Th2 polarization of the immune response and the involvement of dendritic cells (DC) and Th1 lymphocytes in the pathogenesis of uveitis. Thirty-seven patients with chronic idiopathic uveitis were enrolled: 21 of them had active uveitis and the remaining 16 were in complete remission. Patients with active uveitis were characterized as follows: 5 had intermediate uveitis, 5 panuveitis and the remaining 11 posterior uveitis. Thirteen healthy subjects were also studied as controls. Patients with active uveitis were treated with cyclosporin-A (CsA) associated to low doses of prednisone (PDS) and studied at baseline and after 6 months of therapy. Analysis of cytokine-producing CD3+ lymphocytes revealed a strong Th1 polarization of the immune response in patients with active uveitis. Th1 lymphocytes paralleled serum IL-12 levels and the response to therapy, which greatly reduced both IFN-gamma+/CD3+ lymphocytes and serum IL-12 levels, associated with a general clinical improvement. In vitro studies demonstrated that DC from untreated patients with active uveitis were mature and functionally active. In fact, they showed a higher ability to stimulate cell proliferation of allogeneic T cells in primary mixed lymphocyte reaction (MLR) and produced larger amounts of IL-12 than DC from CsA/PDS-treated patients and those in remission. These results demonstrate that CsA/PDS therapy impairs the capacity of mature DC to secrete IL-12 and inhibits their MLR activity.

Pertussis toxin enhances Th1 responses by stimulation of dendritic cells

Pertussis toxin (PTX) has been widely used as an adjuvant to induce Th1-mediated organ-specific autoimmune diseases in animal models. However, the cellular and molecular mechanisms remain to be defined. In this study, we showed that dendritic cells (DC) stimulated with PTX (PTX-DC) were able to substitute for PTX to promote experimental autoimmune uveitis (EAU). EAU induced by PTX-DC revealed a typical Th1 response, characterized by high uveitogenic retinal Ag interphotoreceptor retinoid-binding protein (IRBP)-specific IFN-gamma and IL-12 production in the draining lymph nodes, as well as increased levels of anti-IRBP IgG2a and decreased levels of anti-IRBP IgG1 in the serum of IRBP-immunized mice. Furthermore, PTX-DC preferentially induced T cells to produce the Th1 cytokine, IFN-gamma. After being stimulated with PTX, DC exhibited up-regulation of MHC class II, CD80, CD86, CD40, and DEC205. PTX-DC had also increased allostimulatory capacity and IL-12 and TNF-alpha production. Serum IL-12 was increased in naive mice that received PTX-DC i.p. In addition, PTX activated extracellular signal-regulated kinase in DC. Following the inhibition of extracellular signal-regulated kinase signaling, the maturation of PTX-DC was reduced. Subsequently, the ability of PTX-DC to promote IFN-gamma production by T cells in vitro and to induce EAU in vivo was blocked. The results suggest that PTX might exert an adjuvant effect on DC to promote their maturation and the production of proinflammatory cytokines, thereby eliciting a Th1 response.

Tumour necrosis factor-alpha is a fundamental cytokine in autoimmune thyroid disease induced by thyroglobulin and lipopolysaccharide in interleukin-12 p40 deficient C57BL/6 mice

Experimental autoimmune thyroiditis (EAT) is inducible in mice by immunization with mouse thyroglobulin (mTg) together with adjuvant, either lipopolysaccharide (LPS) or complete Freund's adjuvant (CFA). The severity of the disease is dependent on the mouse strain and on the adjuvant used. We have previously shown that interleukin (IL)-12 deficient C57BL/6 mice immunized with mTg and CFA develop a significantly less severe thyroid infiltration in comparison to wild type C57 BL/6 mice. This result indicated a pivotal role for IL-12 in the development of thyroiditis induced with CFA and mTg. In the present study we demonstrate that IL-12 deficiency does not impair EAT induction when LPS is used as adjuvant. We also demonstrate that peritoneal exudate cells from IL-12-deficient mice stimulated in vitro either with LPS or IL-18 secrete high levels of tumour necrosis factor (TNF). Together the results emphasize the difference between the use of CFA and LPS in the induction of EAT, the importance of TNF-alpha for the pathogenesis of LPS-induced EAT, and also show the capacity of IL-12-deficient mice to develop a competent response to LPS.

CpG-ODN-induced inflammation is sufficient to cause T-cell-mediated autoaggression against hepatocytes

Autoimmune diseases are often associated with microbial infections. Molecular mimicry between microbial antigens and self-epitopes has been suggested as a mechanism for breaking self-tolerance and induction of autoimmunity. Since infections also cause inflammatory responses we explored the role of local inflammation in organ-specific autoimmunity. For this purpose, transgenic mice were used expressing the MHC class I molecule Kb exclusively on hepatocytes. These mice exhibit Kb-specific tolerance as exemplified by the acceptance of Kb+ grafts. Inflammatory reactions were induced by injection of immunostimulatory cytosine-phosphorothioate-guanine (CpG)-rich oligodeoxynucleotides (ODN). Application of CpG-ODN is sufficient to break tolerance in vivo, and to cause activation of Kb-specific CD8+ T cells and subsequent autoaggression against hepatocytes. The CpG-ODN-induced inflammation appears to have two major effects. First, it causes infiltration of T cells into the liver parenchyma. Second, adhesion and costimulatory molecules are up-regulated on hepatocytes so that the infiltrating CD8+ T cells encounter Kb on hepatocytes, which display an APC-like phenotype, resulting in activation and tissue damage. Autoimmune hepatitis can be maintained for at least eight weeks by repeated application of CpG-ODN but subsides after termination of the inflammatory stimulus, suggesting the requirement of additional factors for a self-perpetuation of autoimmunity. These observations describe an additional pathway for the induction of autoimmunity, i.e. in the absence of microbial antigens inflammatory reactions alone can lead to infiltration of T cells into organs, resulting in breaking of tolerance and autoaggression. Moreover, the results provide evidence that T cell activation can take place not only in draining lymph nodes but also directly on parenchymal cells.

Cytokines in immunotherapy of experimental uveitis

A better understanding of the basic mechanisms of uveitis and of the role of cytokines in experimental ocular inflammation autoimmune diseases should allow us to define new approaches for therapy. Modulation of the cytokine network by either blocking cytokine activity or administration of regulatory Th2 cytokines has shown its efficacy in several experimental autoimmune diseases including uveitis. However, cytokines present pleiotropic activities and thus may exert different effects depending on the autoimmune diseases, making interventions on their production complex. Anti-cytokine therapy or a combination of anti-cytokine drugs, antibodies, and cytokine gene therapy to synergize the therapeutical effects of other treatments appear to be of interest. Improvements in drug delivery and in biotechnology will also allow us to elaborate new and safe immunomodulatory strategies.

Immune privilege persists in eyes with extreme inflammation induced by intravitreal LPS

Since immune privilege is believed to exist in the eye in order to suppress sight-destroying inflammation, we wondered whether eyes with intraocular inflammation retain the immune privileged state. Intraocular inflammation was induced by injection of lipopolysaccharide (LPS) into the vitreous cavity of BALB/c mouse eyes, which showed a peak in intensity at approximately 9 h. At this time point, inflamed eyes were examined for their capacity to afford immune privilege to injected allogeneic tumor cells, and to promote anterior chamber-associated immune deviation (ACAID) to antigens injected locally. In addition, aqueous humor (AqH) harvested from inflamed eyes was tested for its ability to suppress T cell activation. Surprisingly, eyes with acute, intense intraocular inflammation allowed allogeneic tumor cells to form progressively growing tumors, and these same eyes promoted ACAID. Moreover, AqH harvested from inflamed eyes strongly inhibited T cell activation. We conclude that the type of extreme, intraocular inflammation evoked by intravitreally injected LPS fails to abolish immune privilege in the eye. These findings are discussed in light of the effects of other types of inflammation on the integrity of ocular immune privilege, and with respect to the capacity of the eye to maintain immune privilege by more than one mechanism.

Induction of experimental autoimmune thyroiditis in IL-12-/- mice

Granulomatous experimental autoimmune thyroiditis (G-EAT) is induced by transfer of mouse thyroglobulin (MTg)-sensitized spleen cells activated in vitro with MTg and anti-IL-2R or MTg and IL-12. Previous work suggested that IL-12 was required in vitro for development of G-EAT. To determine whether IL-12 was also required during the induction and/or effector phases, DBA/1 mice with a disrupted IL-12-P40 gene (IL-12(-/-)) were used for EAT induction. Cells from MTg-sensitized IL12(-/-) donors activated in vitro by MTg or MTg and anti-IL2R induced severe EAT in recipient mice. Compared with effector cells from IL-12(+/+) donors, effector cells from IL-12(-/-) donors induced thyroid lesions dominated by lymphocytes with minimal granulomatous changes. Thyroids of recipients of IL-12(-/-) cells expressed less IFN-gamma mRNA and more TGF-beta, IL-4, and IL-10 compared with recipients of IL-12(+/+) cells. When IL-12 was added during in vitro activation, cells from both IL-12(-/-) and IL-12(+/+) donors induced severe G-EAT, and expression of all cytokines except IL-12 was comparable in thyroids of both IL-12(+/+) and IL-12(-/-) recipients. Transfer of cells from IL-12(+/+) or IL-12(-/-) donors into IL-12(+/+) or IL-12(-/-) recipients indicated that IL-12 expressed in thyroids was derived from recipients. Thus, endogenous IL-12 is not absolutely essential for the sensitization and activation of EAT effector cells to induce severe EAT, although it is required in vitro to promote activation of cells to induce severe granulomatous histopathology.

Attenuation of bleomycin-induced pneumopathy in mice by monoclonal antibody to interleukin-12

We previously demonstrated essential roles of the Fas-Fas ligand (FasL) pathway in bleomycin-induced pneumopathy in mice. T lymphocytes and natural killer cells express FasL on activation and use it as a cytotoxic effector molecule. Because interleukin (IL)-12 is known to play a critical role in cell-mediated immunity, we investigated whether anti-IL-12 antibody treatment suppresses the development of this model. The anti-IL-12 antibody treatment decreased the number of apoptotic cells and the degree of inflammation and fibrosis in lung tissue. The results of RT-PCR showed that IL-12p40, IL-12 receptor (R) β2, interferon-γ, tumor necrosis factor-α and FasL mRNAs were upregulated after bleomycin instillation. The upregulation of FasL, IL-12Rβ2, and tumor necrosis factor-α mRNA expression in lung tissue was suppressed by anti-IL-12 antibody treatment. The results of enzyme-linked immunosorbent assay showed that the levels of IL-12p40, but not of IL-12p70, were increased in lung tissue after bleomycin instillation. Although the increase in IL-12Rβ2 mRNA levels suggests that the T helper type 1 cell response may participate in lung injury, the increase in IL-12p40 supports T helper type 2 cell predominance in the fibrotic process of this model. The administration of anti-IL-12 antibody could be a novel therapy against lung injury and pulmonary fibrosis.

Persistence of pathogenic CD4+ Th1-like cells in vivo in the absence of IL-12 but in the presence of autoantigen

Despite recent successful treatment of murine autoimmune disease with anti-IL-12 mAb, it has not yet been addressed whether anti-IL-12 mAb can also be effective in late stages of disease and whether it can provide lasting protection against recurrence, especially during continued presence of autoantigen. We used a newly developed psoriasis model in scid/scid mice, which allows easy tracking of pathogenic T cells, to show that when anti-IL-12 mAb is given for 2 wk (1 mg/wk) in the late stage of severe disease, inflammation is greatly reduced, as measured by ear thickness and histology (scores, 1.1 +/- 0.1 vs 2.0 +/- 0.4). Moreover, prolonged treatment (4 wk) of chronic psoriatic mice with high doses of mAb (1 mg/wk; prolonged active anti-inflammatory treatment (PAAIT)) results in the almost complete resolution of lesions (scores, 0.3 +/- 0.1 vs 2.7 +/- 0.2). Surprisingly, however, despite these significant treatment results, the psoriasis-like lesions return soon after the anti-IL-12 mAb treatment is discontinued. This rapid relapse of disease may be attributed to large populations of activated CD4(+) T cells present in the lymph nodes of PAAIT animals still expressing an effector/memory phenotype (CD45RB(low), L-selectin(low)). Upon stimulation in vitro such PAAIT lymph node cells secrete high amounts of IFN-gamma (129 ng/ml); when transferred into naive scid/scid animals they are able to rapidly induce disease without costimulation. Our data indicates an alternative IL-12-independent pathway for pathogenic Th-1-like cells in vivo during the chronic phase of disease that allows these cells to persist and maintain their pathogenicity in the draining lymph tissue of the autoimmune site.

Experimental allergic neuritis in the SJL/J mouse: induction of severe and reproducible disease with bovine peripheral nerve myelin and pertussis toxin with or without interleukin-12

We report a reproducible model of experimental allergic neuritis (EAN) with severe clinical signs and consistent pathological features in mice. Pertussis toxin (PT) in the presence or absence of murine recombinant interleukin-12 (mrIL-12) was used as an adjuvant with bovine peripheral nerve myelin (BPNM) to induce clinical EAN in SJL/J mice. After immunization with a combination of BPNM in complete Freund's adjuvant (CFA) and PT, mice developed severe consistent signs of EAN. The additional treatment of immunized mice with mrIL-12 prolonged the course of EAN characterized by earlier clinical signs of the disease and delayed the recovery stage. Mice injected with BPNM and CFA without PT developed mild clinical signs. Histological examination of the caudae equinae and the sciatic nerves taken from mice with clinical signs of EAN during the recovery stage revealed severe demyelination, remyelination and remnants of mononuclear cell infiltration. Moderate to severe EAN can be induced in SJL/J mice by the injection of a combination of BPNM in CFA and PT. This model can provide a better understanding of mechanism of demyelination in infiltrating peripheral neuropathy.

Chronic colitis in IL-10-/- mice: insufficient counter regulation of a Th1 response

IL-10-deficient (IL-10-/-) mice, generated by a gene-targeted mutation, develop abnormal immune responses as a result of uncontrolled interactions between antigen presenting cells and lymphocytes. The studies reviewed herein have focused on the enterocolitis that spontaneously develops in IL-10-/- mice. Not unexpectedly, heightened production of proinflammatory mediators accompanied pathologic changes in the gastrointestinal tract of young mutants. In a series of studies, the proinflammatory mediators responsible for initiating the pathogenic response were distinguished from those that were elicited as a consequence of persistent inflammation. We have also investigated the possibility that different mediators are involved in the inductive versus the maintenance phase of disease. The findings of these mechanistic studies as they relate to our understanding of progressive inflammatory disease and the role of IL-10 in controlling the acute and chronic stages are discussed.

The role of IL-12 in the induction of late-phase cellular infiltration in a murine model of allergic conjunctivitis

BACKGROUND

The applied murine model of allergic conjunctivitis mimics human disease, and an immediate hypersensitivity reaction (IHR) and a late-phase cellular reaction typically develop in sensitized mice after topical challenge with the allergen.

OBJECTIVE

We investigated the role of IL-4, IFN-gamma, and IL-12 in the early and late phases of ocular allergy with use of cytokine knockout (KO) mice and neutralizing antibodies.

METHODS

Ragweed-sensitized wild-type or IL-4KO, IL-12KO, IFN-gamma KO, anti-IL-12 mAb-treated, recombinant murine IL-12-treated, and anti-IFN-gamma mAb-treated mice were challenged with the allergen 10 days after the immunization. IHR, cellular infiltration, lymphoproliferative response, and cytokine production from draining lymph nodes were recorded and compared among groups.

RESULTS

We show that IL-12KO mice and anti-IL-12 antibody-treated wild-type animals failed to have a cellular infiltration into the conjunctiva. Treatment with recombinant murine IL-12 also reduced the number of infiltrating PMNs but increased the percentage of mononuclear cells in the conjunctiva compared with controls. IFN-gamma KO mice had a significantly stronger IHR and prolonged infiltration into the conjunctiva after challenge with ragweed than controls.

CONCLUSION

Our data suggest that the presence of IL-12, although better known as a T(H)1-inducing cytokine, is important for the development and the regulation of the late-phase pathologic features in ocular allergy. Furthermore, IFN-gamma is a limiting factor in the late phase of allergy and thus may be important in preventing chronic allergic disease.

Free radical mediated photoreceptor damage in uveitis

Uveitis is a major cause of blindness, with the visual loss that occurs being due primarily to retinal tissue damage. The tissue damage is mediated mainly by phagocytic inflammatory cells, such as macrophages, by the release of various proteolytic enzymes, arachidonic acid metabolites, cytokines and free radicals. The latter are found to be potent cytotoxic agents that readily cause tissue damage by peroxidation of lipid cell membranes. Recent studies of experimental uveitis indicate that other potent oxidants are generated in uveitis by macrophages. One of these is ONOO-, which is formed from *NO and O(-)2. The macrophages generate *NO preferentially in the outer retina following iNOS expression. In these phagocytes, outer retinal proteins, especially arrestin, are found to be potent iNOS inducers. Current studies of RPE show that these cells protect the retina from ONOO- mediated damage in uveitis by releasing a novel protein called retinal pigment epithelial protective protein. This protein is found to suppress O(-)2 and *NO generation by the phagocytes, in both in vitro and in vivo uveitis models. The protective protein expression is restricted to RPE, its suppressive effect is a result of the inhibition of the phosphorylation of cytosolic proteins, p47-phox, required for the assembly of NADPH and activation of NFkappaB, which are required for generation of 0(-)2 and expression of iNOS respectively. Either pharmacologically or chemically, up-regulation of RPP generation could help in preventing retinal degeneration in uveitis or other degenerative dis

Cytokines that regulate autoimmune responses

Autoimmune responses are controlled by complex regulatory circuits. Previous work has revealed that factors controlling autoimmunity can act both as potentiating and inhibitory agents, depending upon the site and timing of exposure. Recent advances in this complex field have at least partially uncovered the mechanism whereby these regulatory molecules participate in autoimmune processes. IL-12 production in the absence of infection may predispose to autoimmunity. IL-4 and transforming growth factor beta may suppress autoreactive T cells. Proinflammatory cytokines may ameliorate autoimmunity, dependent on the timing and level of production. In many cases, cytokines may act via antigen-presenting cells.

The involvement of IL-12 in murine experimentally induced autoimmune thyroid disease

Experimental autoimmune thyroid disease (EAT) can be induced experimentally in mice following immunization with mouse thyroglobulin (mTg) and the adjuvants lipopolysaccharide (LPS) or complete Freund's adjuvant (CFA). EAT can also be transferred to naive recipients by CD4+ T cells from mTg-primed mice. Here we demonstrate a role for IL-12 in the development of EAT by the ability of neutralizing antibody to IL-12 to reduce disease severity and by the lack of significant levels of thyroid infiltration in IL-12p40-deficient mice following immunization with mTg and CFA. A single injection of 300 ng IL-12 at the time of initial immunization with mTg and LPS was able to increase the degree of thyroid infiltration. These data are all consistent with EAT being a Th1-mediated disease. Conversely, however, administration of IL-12 over a prolonged period markedly inhibited the induction of EAT by mTg and CFA and, if given to recipients, inhibited the transfer of EAT by mTg-primed lymph node cells. The development of an autoantibody response to mTg was also inhibited when IL-12 was administered throughout the experimental period, suggesting that sustained exposure to IL-12 can be immunosuppressive.

Analysis of effects of stimulation in vitro of ovalbumin primed lymph node cells on adoptive transfer of experimental immune mediated blepharoconjunctivitis in Lewis rats

AIM

To analyse the role of stimulation in vitro of lymphocytes on the augmentation of experimental immune mediated blepharoconjunctivitis (EC, formerly EAC) in Lewis rats induced by adoptive transfer.

METHODS

Two weeks after immunisation with ovalbumin (OVA), rat draining lymph nodes were collected and 50 x 10(6) cells were injected into naive syngeneic recipients either directly or after culture in vitro with OVA, concanavalin A (Con A), or purified protein derivative (PPD) for 3 days. Four days after injection the rats were topically challenged with OVA. 24 hours later, they were sacrificed and eyes and spleens were harvested for histology and proliferation assay. In some experiments, naive recipient rats were irradiated with 7 Gy gamma ray before transfer. The expression of adhesion molecules and cytokine profile of OVA primed lymph node cells were also investigated.

RESULTS

Both infiltrated cell number and splenocyte proliferation in the recipients of stimulated cells were higher than those of unstimulated cells. In vitro stimulation with OVA or Con A induced a severe cellular infiltration, while stimulation with PPD did not. Irradiation markedly diminished cellular infiltration. Stimulation in vitro upregulated the CD4/CD8 ratio by four times and augmented expression of CD25, I-A, ICAM-1 molecules on OVA primed lymph node cells by about five times. IFN-gamma was detected in OVA primed cells by stimulation in vitro, while IL-4 mRNA was extinguished by stimulation in vitro.

CONCLUSIONS

Augmentation of EC by stimulation in vitro of transferred lymphocytes might depend on the upregulation of expression of cell surface molecules and cytokine shift as well as augmented antigen specificity.

Decreased IL-12 production and Th1 cell development by acetyl salicylic acid-mediated inhibition of NF-kappaB

IL-12 is a 75-kDa heterodimeric cytokine composed of two covalently linked p35 and p40 chains. This pro-inflammatory cytokine plays a prominent role in the development of Th1 cell-mediated immune responses. Th1 cell-mediated immune responses have been implicated in the pathogenesis of chronic inflammatory autoimmune diseases. Thus, IL-12 appears to be a critical factor in the generation and maintenance of chronic inflammatory conditions. In this study, we investigated the effects of a commonly prescribed anti-inflammatory drug, acetyl salicylic acid (ASA), on IL-12 production and Th1 cell development. ASA was found to inhibit secretion of the IL-12 heterodimer as well as p40 monomer by human monocytic cells. This was associated with the down-regulation of IL-12p40 mRNA expression. Analysis of the regulation of the p40 gene promoter revealed that ASA inhibited NF-kappaB activation and binding to the p40-kappaB site in the p40 promoter, leading to transcriptional repression of the p40 gene. Addition of ASA to an in vitro T helper cell differentiation system, at concentrations compatible with plasma levels reached during anti-inflammatory therapy, resulted in reduced development of Th1 cells. These results suggest that the inhibition of NF-kappaB activation by ASA leads to down-regulation of IL-12 production and inhibition of Th1 cell development.

IL-12, But Not IFN-γ, Plays a Major Role in Sustaining the Chronic Phase of Colitis in IL-10-Deficient Mice

IL-10-deficient (IL-10−/−) mice develop chronic enterocolitis mediated by CD4+ Th1 cells producing IFN-γ. Because IL-12 can promote Th1 development and IFN-γ production, the ability of neutralizing anti-IL-12 mAb to modulate colitis in IL-10−/− mice was investigated. Anti-IL-12 mAb treatment completely prevented disease development in young IL-10−/− mice. Treatment of adult mice resulted in significant amelioration of established disease accompanied by reduced numbers of mesenteric lymph node and colonic CD4+ T cells and of mesenteric lymph node T cells spontaneously producing IFN-γ. In contrast, anti-IFN-γ mAb had minimal effect on disease reversal, despite a significant preventative effect in young mice. These findings suggested that IL-12 sustains colitis by supporting the expansion of differentiated Th1 cells that mediate disease independently of their IFN-γ production. This conclusion was supported by the finding that anti-IL-12 mAb greatly diminished the ability of a limited number of CD4+ T cells expressing high levels of CD45RB from diseased IL-10−/− mice to expand and cause colitis in recombination-activating gene-2−/− recipients, while anti-IFN-γ mAb had no effect. Furthermore, IL-12 could support pathogenic IL-10−/− T cells stimulated in vitro in the absence of IL-2. While these studies show that IL-12 plays an important role in sustaining activated Th1 cells during the chronic phase of disease, the inability of anti-IL-12 mAb to abolish established colitis or completely prevent disease transfer by Th1 cells suggests that additional factors contribute to disease maintenance.

IL-12 is involved in the induction of experimental autoimmune myasthenia gravis, an antibody-mediated disease

IL-12 has been shown to be involved in the pathogenesis of Th1-mediated autoimmune diseases, but its role in antibody-mediated autoimmune pathologies is still unclear. We investigated the effects of exogenous and endogenous IL-12 in experimental autoimmune myasthenia gravis (EAMG). EAMG is an animal model for myasthenia gravis, a T cell-dependent, autoantibody-mediated disorder of neuromuscular transmission caused by antibodies to the muscle nicotinic acetylcholine receptor (AChR). Administration of IL-12 with Torpedo AChR (ToAChR) to C57BL/6 (B6) mice resulted in increased ToAChR-specific IFN-gamma production and increased anti-ToAChR IgG2a serum antibodies compared with B6 mice primed with ToAChR alone. These changes were associated with earlier and greater neurophysiological evidence of EAMG in the IL-12-treated mice, and reduced numbers of AChR. By contrast, when IL-12-deficient mice were immunized with ToAChR, ToAChR-specific Th1 cells and anti-ToAChR IgG2a serum antibodies were reduced compared to ToAChR-primed normal B6 mice, and the IL-12-deficient mice showed almost no neurophysiological evidence of EAMG and less reduction in AChR. These results indicate an important role of IL-12 in the induction of an antibody-mediated autoimmune disease, suggest that Th1-dependent complement-fixing IgG2a anti-AChR antibodies are involved in the pathogenesis of EAMG, and help to account for the lack of correlation between anti-AChR levels and clinical disease seen in many earlier studies.

Neutralizing TNF-alpha activity modulates T-cell phenotype and function in experimental autoimmune uveoretinitis

Inhibiting TNF-alpha activity prevents tissue destruction without inhibiting retinal T cell infiltration in experimental autoimmune uveoretinitis (EAU) in Lewis rats. To further determine the role of TNF-alpha in autoimmune uveitis we characterized T cells isolated from retinae after treatment with a TNF-alpha antagonist. TNF-alpha activity was neutralized in vivo with a p55 TNF-alpha receptor-Ig fusion protein (sTNFr-Ig), administered 8 and 10 days after induction of EAU with heterologous retinal antigens. Retinal T-cell phenotype expression was examined by flow cytometry with respect to OX22 status (CD45RBlow or CD45RBhigh), activation (OX40 and CD25 expression) and rate of T-cell apoptosis (Annexin V+PI- expression). Lymphocyte reactivity was assessed by proliferation responses and cytokine production to retinal antigens. Despite greater than 40% of CD4+ T cells being activated at the height of disease, the proportion of OX22low expression was reduced and T cells exhibited reduced IFN-gamma and elevated IL-4 production. Retinal T cells maintained antigen-specific proliferation and demonstrated a low apoptotic rate. Although in both animal groups, comparable numbers of T cells were isolated, neutralizing TNF activity suppressed Th1 effector mechanisms protecting against target organ damage.

Recombinant adenovirus encoding gp100 modulates experimental melanin-protein induced uveitis (EMIU)

Experimental melanin-protein induced uveitis (EMIU) is a T-cell mediated autoimmune uveitis induced by immunization with bovine uveal melanin protein. Gp100, a melanocyte lineage-specific protein, is identified as a human melanoma antigen. A recombinant adenovirus construct encoding gp100 (Ad2CMV-gp100) has been used as a vaccine for cancer therapy. This study examines the effect of Ad2CMV-gp100 on EMIU. To induce EMIU, rats were injected intraperitoneally on day 7 before immunization with ad2CMV-gp100, control adenovirus encoding LacZ (Ad2CMV-LacZ), or no virus. On day 21 after immunization, the right eye was processed for histology and the left eye was analysed for cytokines by quantitative reverse transcriptase-polymerase chain reaction. Western blot analysis showed that uveal melanin-protein contains gp100. In three independent experiments, ocular inflammation was significantly suppressed, and expression of ocular IL-12p40 mRNA was much lower in the rats which received Ad2CMV-gp100 before immunization than in those that received Ad2CMV-LacZ or no virus. No abnormalities developed in rats which received Ad2CMV-gp100 or Ad2CMV-LacZ alone. Therefore, Ad2CMV-gp100 injection prevents the development of EMIU, at least in part, through cytokine regulation.