Immune corticotropin-releasing hormone is present in the eyes of and promotes experimental autoimmune uveoretinitis in rodents.

We examined the presence and potential role of local corticotropin-releasing hormone (CRH) in experimental uveitis in rodents. This 41-amino acid peptide, originally isolated from the hypothalamus, is also secreted locally in experimentally induced and natural inflammatory sites, where it exerts autocrine or paracrine proinflammatory effects. Female Lewis rats were immunized with the major pathogenic epitope (R16 peptide) of the interphotoreceptor retinoid-binding protein in complete Freund's adjuvant, monitored daily, and killed 8, 9, 10, 12, 14, or 18 days later, after having developed uveoretinitis. Immunoreactive CRH (IrCRH) was detected by immunohistochemistry in the uveitic eyes in the cytoplasm of inflammatory cells (macrophages, lymphocytes, and polymorphonuclear cells) infiltrating the iris, ciliary body, vitreous, retina, and choroid depending on the stage of the disease. The intensity of the IrCRH staining was positively correlated with the severity of the disease based on morphological criteria. The amount of IrCRH measured by RIA varied between 0.18 +/- 0.03 (mean +/- SE) and 0.79 +/- 0.07 pmol/g wet tissue (8th and 14th day of the disease, respectively). Ophthalmic IrCRH in uveitic rat eyes had similar chromatographic mobility as rat/human CRH-(1-41) by HPLC. Furthermore, female B10.A mice were immunized with interphotoreceptor retinoid-binding protein and treated during the induction (0-7 days) or expression (8-16 days) stages of the disease with ip injections of the anti-CRH antibody TS-2 or placebo nonimmune rabbit serum. The early anti-CRH treatment significantly decreased the disease intensity compared to that in placebo- or late-treated animals (P < 0.05, by analysis of variance). We conclude that IrCRH is present at the site of inflammation in rodent experimental uveitis and that its expression correlates with the natural history and intensity of the disease. Immune CRH appears to play an early pathogenetic role in the induction of experimental uveitis.

Anti-tumor necrosis factor alpha therapy suppresses the induction of experimental autoimmune uveoretinitis in mice by inhibiting antigen priming.

PURPOSE: Experimental autoimmune uveoretinitis (EAU) serves as a model for several immune-mediated diseases that affect the eye in humans. Previous studies indicated that tumor necrosis factor alpha (TNF-alpha) has an important proinflammatory role in EAU and possibly in human uveitis. In this study, the authors investigated the effect of anti-TNF-alpha therapy on EAU in mice. METHODS: Experimental autoimmune uveoretinitis was induced in B10.A mice by immunization with interphotoreceptor retinoid-binding protein (IRBP). The mice were treated with 100 or 300 microliters rabbit antiserum or polyclonal antibodies to human TNF-alpha. The treatment spanned either the afferent or the efferent stage of EAU (days -1, 1, 3, 5, 7, or days 8, 10, 12, 14, 16, respectively). Control animals were injected with preimmune rabbit serum at the corresponding times or were not treated. Three weeks after immunization, EAU was assessed by clinical evaluation and by histopathology. Immunologic responses were assessed by delayed-type hypersensitivity (DTH), lymphocyte proliferation to IRBP, and relative abundance of IRBP-primed splenocytes. RESULTS: The treatment with rabbit anti-TNF-alpha serum significantly ameliorated disease when given during the afferent stage but had no effect when given during the efferent stage of EAU. The effect on DTH, lymphocyte proliferation, and abundance of antigen-reactive cells roughly paralleled the effect on disease. CONCLUSIONS: Neutralization of systemic TNF ameliorates EAU. The effectiveness of afferent treatment in comparison to the treatment during the efferent stage, together with the reduced proliferation and the reduced abundance of IRBP-responsive cells, suggest that interference with afferent-acting processes such as antigen priming is important to achieve protection from EAU by anti-TNF treatment.

T cell traffic and the inflammatory response in experimental autoimmune uveoretinitis.

PURPOSE: To quantify S-antigen-specific (S-Ag) T cells in the retina after adoptive transfer, and to evaluate their role in the initiation and progress of destructive ocular inflammation in experimental autoimmune uveoretinitis (EAU). METHODS: Lewis rats were administered 10 x 10(6) S-Ag-specific T cells from the SP35 cell line or 10 x 10(6) concanavalin A-stimulated syngeneic spleen cell lymphoblasts labeled with lipophilic PKH26 fluorescent dye immediately before intravenous inoculation. Labeled cells in each retina were counted at various times from 4 to 120 hours after cell transfer by fluorescence microscopic analysis of each dissociated retina. Recipient eyes were examined within the same period by light and confocal microscope. RESULTS: SP35 T cells showed a biphasic distribution in the retina. The first peak of 160 cells/retina was noted at 24 hours. A steady decline of labeled cells at 48 and 72 hours was followed by a rapid increase at 96 and 120 hours. Concanavalin A-stimulated, control-labeled cell populations showed an identical peak at 24 hours but a persistent decline thereafter; only two or three T cells were present in each retina at 120 hours. Concurrent inoculation of SP35 cells and nonspecific T cell blasts did not produce more SP35 cells than control cells in the retina at any time. Microscopic analysis showed mononuclear cell infiltration of the iris, ciliary body, and aqueous humor at 48 hours, which intensified rapidly and persisted through 120 hours. Retinal inflammation did not begin until 80 hours. Mononuclear cell adherence to vascular endothelium and perivascular macrophage infiltration of the innermost layers progressed to edema, and profound destructive inflammation and loss of retinal stratification were observed at 120 hours. CONCLUSIONS: There is no evidence of a blood-ocular or blood-retinal barrier to activated T cell blasts. Autologous S-Ag does not provoke a more rapid entry of specific T cells at that site. The data confirm that anterior segment inflammation precedes retinal inflammation, even though S-Ag-specific T cells were present in the retina within a few hours after cell transfer. Because S-Ag is clearly present in the retina, delay in antigen presentation at that site may account for the temporal difference between retinal and anterior segment inflammation.

Suramin treatment suppresses induction of experimental autoimmune uveoretinitis (EAU) in rodents.

The experimental drug suramin has been shown to possess several immunosuppressive properties. In this study we investigated the effect of suramin on the development of experimental autoimmune uveoretinitis (EAU) in mice and in rats. EAU was induced either by active immunization with a uveitogenic protein or peptide, or by the adoptive transfer of a uveitogenic T cell line. The development of EAU was assessed by clinical evaluation as well as by histopathology. Immunological responses were measured by delayed type hypersensitivity (DTH), lymphocyte proliferation, and serum antibody levels to the immunizing antigen. Suramin treatment was most effective in suppressing EAU when started concurrently with immunization (afferent). Treatment was less effective in suppressing disease when first administered 7 days after immunization or when given to animals that received an adoptive transfer of uveitogenic T cells (efferent). The effect of suramin on DTH and lymphocyte proliferation roughly paralleled its effect on EAU. Aferent treatment of mice with suramin completely suppressed anti-IRBP antibody titers. Interestingly, animals receiving efferent treatment had unreduced IgM levels but little or no IgG, suggesting prevention of the IgM-to-IgG switch. Depressed in vitro lymphocyte proliferative responses in animals treated with suramin during the afferent stage suggested that the suppressive effect on disease was due at least in part to an inhibition of antigen priming. Our results suggest that suramin merits further investigation as a potential treatment for some types of uveitis.

Seroprevalence of antibodies against Toxoplasma gondii among two rural populations in northern Israel.

The prevalence of antibodies against Toxoplasma gondii was measured in two rural populations in northern Israel--Jewish kibbutz members and Arab villagers. The respective prevalences in these two populations were 22.2% and 55.8% (P < 0.001). No correlation was found between the presence of antibodies and sex, occupation, contact with cats, a history of fever and/or lymphadenopathy, eye disease, abortions or delivery of children with congenital malformations. In contrast to Jewish children who were not found to have antibodies in the first decade of life, 20.5% of Arab children tested positive. A gradual increase in the prevalence of antibodies with age was seen in both groups, with the Jews reaching a prevalence of 42.6% at age 60+ and the Arabs reaching 74% at age 40. The difference between the two groups probably stems from different eating habits, namely ingestion of raw meat and unpasteurized milk and milk products.