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R R Caspi

Publications and source records attributed to R R Caspi.

At least 19 recordsLinked to original sources
PubMed2001

Pertussis toxin inhibits induction of tissue-specific autoimmune disease by disrupting G protein-coupled signals.

Pertussis toxin (PTX) has been used for many years as an adjuvant that promotes development of tissue-specific experimental autoimmune diseases such as experimental autoimmune encephalomyelitis, experimental autoimmune uveitis (EAU), and others. Enhancement of vascular permeability and of Th1 responses have been implicated in this effect. Here we report a surprising observation that, in a primed system, PTX can completely block the development of EAU. Disease was induced in B10.RIII mice by adoptive transfer of uveitogenic T cells, or by immunization with a uveitogenic peptide. A single injection of PTX concurrently with infusion of the uveitogenic T cells, or two injections 7 and 10 days after active immunization, completely blocked development of EAU. EAU also was prevented by a 1-h incubation in vitro of the uveitogenic T cells with PTX before infusing them into recipients. Uveitogenic T cells treated with PTX in vitro and lymphoid cells from mice treated with PTX in vivo failed to migrate to chemokines in a standard chemotaxis assay. Neither the isolated B-oligomer subunit of PTX that lacks ADP ribosyltransferase activity nor the related cholera toxin that ADP-ribosylates G(s) (but not G(i)) proteins blocked EAU induction or migration to chemokines. We conclude that PTX present at the time of cell migration to the target organ prevents EAU, and propose that it does so at least in part by disrupting signaling through G(i) protein-coupled receptors. Thus, the net effect of PTX on autoimmune disease would represent an integration of enhancing and inhibitory effects.

Adoptive Transfer↗
PubMed2001

Fas/Fas ligand-associated apoptosis in experimental autoimmune uveoretinitis in rodents: role of proinflammatory corticotropin-releasing hormone.

We have previously shown that corticotropin-releasing hormone plays an important proinflammatory role in the induction of experimental autoimmune uveoretinitis. In this study, we examined the role of apoptosis in the destruction of the retina during experimental autoimmune uveoretinitis, and the role of corticotropin-releasing hormone as a local regulator of Fas and Fas Ligand expression in this condition. We evaluated apoptosis by the terminal deoxynucleotidyl transferase dUTP nick end labeling method and Fas and Fas Ligand presence by immunohistochemistry. We examined formalin-fixed, paraffin-embedded eye sections from female Lewis rats or B10.A mice immunized with the major pathogenetic epitope (R16 peptide) of the interphotoreceptor retinoid-binding protein. Female B10.A mice similarly immunized were treated with intraperitoneal injections of the rabbit anti-corticotropin-releasing hormone antibody TS-2 or nonimmune rabbit serum. The percentage of retinal cells undergoing apoptosis and the expression of Fas and Fas Ligand were increased in inflamed retinas in immunized Lewis rats and B10.A mice, compared to controls. Retinas from immunized B10.A mice treated with anti-corticotropin-releasing hormone antibody showed significantly lower apoptosis and Fas and Fas Ligand expression than placebo-treated animals. In conclusion, retinal cells in experimental autoimmune uveoretinitis undergo apoptosis associated with concurrent upregulation of Fas and Fas Ligand. The local presence of corticotropin-releasing hormone appears to be of pivotal importance in this process.

Animals↗
PubMed2000

Fas and Fas ligand expressed on cells of the immune system, not on the target tissue, control induction of experimental autoimmune uveitis.

The Fas-Fas ligand (FasL) interaction is important for maintaining lymphocyte homeostasis by signaling for activation-induced cell death. Mice homozygous for the lpr or gld mutations do not express functional Fas or FasL, respectively, and spontaneously develop progressive autoimmune symptoms. Recent studies implicated expression of FasL on immunologically privileged tissues in protection from immune-mediated damage. Conversely, tissue expression of Fas may facilitate damage. We evaluated the susceptibility of lpr and gld mice to induction of experimental autoimmune uveitis (EAU), a T cell-mediated autoimmune disease induced with retinal Ags, which targets the neural retina. gld as well as lpr mice immunized with a retinal Ag developed disease of lower incidence and severity than wild-type controls. Delayed hypersensitivity responses were not significantly different among immunized gld, lpr, or wild-type mice, although in vitro Ag-specific lymphocyte responses of the mutant mice were lower. To evaluate whether the diminished ability of gld and lpr mice to develop EAU was due to a defect at the level of the tissue or the immune system, radiation bone marrow chimeras constructed between wild-type and mutant mice were immunized to induce EAU. Mutant recipients of wild-type bone marrow, but not wild-type recipients of mutant bone marrow, developed normal disease scores. These results indicate that normal expression of Fas and of FasL on cells of the immune system is important for EAU expression. Unexpectedly, neither lack of Fas nor lack of FasL on the ocular tissues affected expression of EAU.

Animals↗
PubMed2000

Blockade of costimulation through B7/CD28 inhibits experimental autoimmune uveoretinitis, but does not induce long-term tolerance.

It has been reported that costimulation blockade can result in T cell anergy. We investigated the effects of blocking costimulatory molecules in vivo on the development of experimental autoimmune uveoretinitis (EAU), a model for autoimmune uveitis in humans that is induced in mice by immunization with the retinal Ag interphotoreceptor retinoid binding protein. B10.A mice immunized with a uveitogenic regimen of interphotoreceptor retinoid-binding protein were treated with Abs to B7.1 and B7.2 for 2 wk. Evaluation of EAU and immunological responses 1 wk later showed that disease had been abrogated, and cellular responses were suppressed. To determine whether the costimulation blockade resulted in tolerance, adult-thymectomized mice immunized for uveitis and treated with anti-B7 or anti-CD28 were rechallenged for uveitis induction 5 wk after the initial immunization. Although confirmed to be disease free after the initial immunization, both anti-B7- and anti-CD28-treated mice developed severe EAU and elevated cellular responses after the rechallenge, equivalent to those of control mice. We conclude that in this model costimulatory blockade in vivo prevents the development of autoimmune disease, but does not result in long-term tolerance. The data are compatible with the interpretation that B7/CD28 blockade prevents generation of effector, but not of memory, T cells.

Animals↗
PubMed2000

Transgenic expression of an immunologically privileged retinal antigen extraocularly enhances self tolerance and abrogates susceptibility to autoimmune uveitis.

Interphotoreceptor retinoid-binding protein (IRBP) is an immunologically privileged retinal antigen that can elicit experimental autoimmune uveitis (EAU). The nature and extent of tolerance to immunologically privileged self antigens is poorly understood. To investigate whether transgenic expression of IRBP extraocularly enhances tolerance and protects from EAU we prepared mice that express half of the mouse IRBP gene, containing a potent uveitogenic epitope (residues 161 - 180), under control of MHC class II promoter. Transgene mRNA was detectable in many tissues. Transgenic protein was undetectable by conventional assays, but was detected in thymic tissue by lymphocyte proliferation assay after induction of the promoter. Transgenic mice challenged with p161 - 180 did not develop EAU and had reduced immunological responses, but remained susceptible to EAU induced by whole IRBP, that contains additional uveitogenic epitopes. Disease was also induced by wild type T cells specific to p161 - 180. Thus, extraocular expression of a privileged retinal antigen enhances self tolerance, supporting the notion that sequestration contributes to immune privilege. Exceedingly low levels of transgene expression result in tolerance that is both profound and epitope specific, implying anergy or deletion of the endogenous uveitogenic repertoire. The same level of expression is, however, insufficient to tolerize wild-type effector T cells in the periphery.

Amino Acid Sequence↗
PubMed2000

Evaluation of in vivo cytokine expression in EAU-susceptible and resistant rats: a role for IL-10 in resistance?

Messenger RNAs for six cytokines (IL-12p40, IFN-gamma, IL-10, IL-4, TNF-alpha and TGF-beta1) expressed in vivo during development of experimental autoimmune uveitis (EAU) were quantitated by PCR in (uncultured) peripheral lymphoid cells and in the eyes of EAU-susceptible Lewis and EAU resistant F344 rats. Disease was induced by immunization with the R16 peptide of IRBP (in RT1B haplotype rats) or with whole IRBP (in all haplotypes). In the periphery, both Lewis and F 344 expressed similar cytokine patterns. In ocular tissues, however, only Lewis expressed elevated type 1 and inflammatory cytokines (IL-12p40, IFN-gamma and TNF-alpha), coincident with onset and peak of disease. Interestingly, naive F344 rats expressed higher basal levels of IL-10 mRNA in the eyes. To examine the possible involvement of this phenomenon in resistance, basal levels of IL-10 vs susceptibility to IRBP were compared in Lewis, BN, DA. F344 and ACI strains. Lewis, BN and DA were susceptible and had low levels of IL-10 mRNA in eyes. F344 and ACI were resistant and expressed high basal levels of IL-10 mRNA. In an in vitro study, recombinant rat IL-10 (but not human or mouse IL-10) suppressed lymphocyte proliferation and IFN-gamma production by primed lymph node cells of R16 immunized rats, but did not suppress uveitogenic long-term T-cell lines polarized to the Thl phenotype, suggesting that mature effector lymphocytes in the rat may lose their ability to be suppressed by IL-10. We propose that higher expression of the IL-10 gene in ocular tissues in some rat strains may represent a mechanism that contributes to a higher threshold of resistance to EAU, but this threshold may be overcome by a more mature Thl effector with a reduced sensitivity to IL-10.

Animals↗
PubMed2000

Residues 1-20 of IRBP and whole IRBP elicit different uveitogenic and immunological responses in interferon gamma deficient mice.

Experimental autoimmune uveoretinitis (EAU) is a T-cell-mediated autoimmune disease induced by immunization with uveitogenic retinal antigens, or by the adoptive transfer of uveitogenic T-cells of the Th-1-like phenotype. We have previously shown that IFN-gamma-deficient mice (GKO) on the C57BL/6 background are equally susceptible to interphotoreceptor retinoid binding protein (IRBP)-induced EAU as the wild type (WT). In the present study, we evaluated EAU induction in GKO mice by the newly described H-2(b)epitope contained in residues 1-20 of human IRBP, and compared it to the response to the whole IRBP molecule. Similarly to previous observations with IRBP-induced EAU, delayed type hypersensitivity (DTH) and lymphocyte proliferation responses were elevated in GKO mice, as was production of IL-5 and TNF-alpha. However, unlike the responses induced by whole IRBP, there was no detectable IL-10 production to the peptide. Histopathology on day 21 after immunization, revealed that both GKO and WT mice developed retinal lesions, including damage to the photoreceptor cell layer, vasculitis and inflammatory cellular infiltration, but disease scores were significantly higher in GKO, and retinal detachment was observed only in GKO mice. In contrast to the wild type, the cellular infiltrate in eyes of GKO mice contained a prominent component of eosinophils, although of lower proportion in peptide-induced than in IRBP-induced EAU. We conclude that the cytokine and inflammatory responses to human peptide 1-20 differ perceptibly from the responses to whole bovine IRBP, and may explain the elevated EAU scores of GKO mice compared to wild type.

Animals↗
PubMed2000

Retroviral gene therapy with an immunoglobulin-antigen fusion construct protects from experimental autoimmune uveitis.

Immunoglobulins can serve as tolerogenic carriers for antigens, and B cells can function as tolerogenic antigen-presenting cells. We used this principle to design a strategy for gene therapy of experimental autoimmune uveitis, a cell-mediated autoimmune disease model for human uveitis induced with the uveitogenic interphotoreceptor retinoid-binding protein (IRBP). A retroviral vector was constructed containing a major uveitogenic IRBP epitope in frame with mouse IgG1 heavy chain. This construct was used to transduce peripheral B cells, which were infused into syngeneic recipients. A single infusion of transduced cells, 10 days before uveitogenic challenge, protected mice from clinical disease induced with the epitope or with the native IRBP protein. Protected mice had reduced antigen-specific responses, but showed no evidence for a classic Th1/Th2 response shift or for generalized anergy. Protection was not transferable, arguing against a mechanism dependent on regulatory cells. Importantly, the treatment was protective when initiated 7 days after uveitogenic immunization or concurrently with adoptive transfer of primed uveitogenic T cells. We suggest that this form of gene therapy can induce epitope-specific protection not only in naive, but also in already primed recipients, thus providing a protocol for treatment of established autoimmunity.

Animals↗
PubMed2000

Identification of a new epitope of human IRBP that induces autoimmune uveoretinitis in mice of the H-2b haplotype.

PURPOSE: Experimental autoimmune uveoretinitis (EAU) is a T-cell-mediated disease induced by immunization with interphotoreceptor retinoid binding protein (IRBP). Major uveitogenic sites have been identified for mice of the H-2r and H-2k haplotypes but not for the H-2b haplotype. The present communication describes the characterization of an epitope contained in residues 1 to 20 of human IRBP that induces EAU in H-2b mice. METHODS: H-2b (C57BL/6, 129/J) and H-2r (BIO.RIII) mice were immunized with peptide 1-20 or with whole (bovine) IRBP. EAU (histopathology) and immunologic responses (delayed-type hypersensitivity [DTH], lymphocyte proliferation, and cytokine production) were assessed after 21 days. RESULTS: C57BL/6 mice, 129/J and (129/JxC57BL/6)F1 mice, immunized with 200 to 300 microg of peptide, developed DTH and EAU with scores comparable to those induced by 100 microg IRBP. Their lymphocytes proliferated to the peptide and produced interferon-gamma (but not interleukin-4) and transferred EAU to syngeneic recipients. Lymphocytes of IRBP-immunized mice also responded to the peptide. Peptide 1-20-immunized B1O.RIII mice failed to develop either disease or immunologic responses. CONCLUSIONS. Human IRBP peptide 1-20 contains a major epitope for the H-2b haplotype, which is apparently not presented by the H-2r haplotype.

Adoptive Transfer↗
PubMed1999

IL-4 and IL-10 are both required for the induction of oral tolerance.

Protection from the development of experimental autoimmune uveitis (EAU) can be induced by feeding mice interphotoreceptor retinoid binding protein before uveitogenic challenge with the same protein. Two different regimens are equally effective in inducing protective tolerance, although they seem to do so through different mechanisms: one involving regulatory cytokines (IL-4, IL-10, and TGF-beta), and the other with minimal involvement of cytokines. Here we studied the importance of IL-4 and IL-10 for the development of oral tolerance using mice genetically engineered to lack either one or both of these cytokines. In these animals we were able to protect against EAU only through the regimen inducing cytokine-independent tolerance. When these animals were fed a regimen that in the wild-type animal is thought to predominantly induce regulatory cells and is associated with cytokine secretion, they were not protected from EAU. Interestingly, both regimens were associated with reduced IL-2 production and proliferation in response to interphotoreceptor retinoid binding protein. These findings indicate that both IL-4 and IL-10 are required for induction of protective oral tolerance dependent on regulatory cytokines, and that one cytokine cannot substitute for the other in this process. These data also underscore the fact that oral tolerance, manifested as suppression of proliferation and IL-2 production, is not synonymous with protection from disease.

Animals↗
PubMed1999

Pregnancy ameliorates induction and expression of experimental autoimmune uveitis.

Female patients suffering from autoimmune uveitis are reported to experience a temporary remission during pregnancy. Experimental autoimmune uveitis (EAU) is a model for human uveitis. Here we examine the effect of pregnancy on the development of EAU and its associated immunological responses. Susceptible C57BL/6 mice were immunized with interphotoreceptor retinoid-binding protein (IRBP). EAU scores and Ag-specific responses were evaluated 21 days later. Mice immunized during pregnancy developed significantly less EAU than nonpregnant controls. Their lymph node cells and splenocytes produced a distinct pattern of cytokines in response to IRBP: reduced IFN-gamma and IL-12 p40, but unchanged levels of TNF-alpha, IL-4, IL-5, and IL-10. Anti-IRBP Ab isotypes revealed an up-regulation of IgG1, indicating a possible Th2 bias at the humoral level. Ag-specific proliferation and delayed hypersensitivity, as well as mitogen-induced IFN-gamma production, remained undiminished, arguing against an overall immune deficit. Interestingly, pregnant mice that received an infusion of IRBP-primed lymphoid cells from nonpregnant donors also developed reduced EAU, suggesting that pregnancy suppresses not only the generation, but also the function of mature uveitogenic effector T cells. Pregnant mice at the time of immunization exhibited elevated levels of TGF-beta, but not of IL-10, in the serum. We suggest that protection from EAU during pregnancy is due primarily to a selective reduction of Ag-specific Th1 responses with only marginal enhancement of Th2 function, and that these effects may in part be secondary to elevated systemic levels of TGF-beta.

Adoptive Transfer↗
PubMed1999

Interleukin 12 protects from a T helper type 1-mediated autoimmune disease, experimental autoimmune uveitis, through a mechanism involving interferon gamma, nitric oxide, and apoptosis.

Pathogenic effector T cells in experimental autoimmune uveitis (EAU) are T helper type 1-like, and interleukin (IL)-12 is required for their generation and function. Therefore, we expected that IL-12 administration would have disease-enhancing effects. Mice were immunized with a uveitogenic regimen of the retinal antigen interphotoreceptor retinoid-binding protein, treated with IL-12 (100 ng/d for 5 d), and EAU was assessed by histopathology. Unexpectedly, IL-12 treatment failed to enhance EAU in resistant strains and downregulated disease in susceptible strains. Only treatment during the first, but not during the second, week after immunization was consistently protective. High levels of interferon gamma (IFN-gamma) were present in the serum during IL-12 treatment, but subsequent antigen-specific IFN-gamma production in protected mice was diminished, as were IL-5 production, lymph node cell proliferation, and serum antibody levels. Treated mice had fewer cells and evidence of enhanced apoptosis in the draining lymph nodes. Unlike wild-type mice, IFN-gamma-deficient, inducible nitric oxide synthase (iNOS)-deficient, and Bcl-2(lck) transgenic mice were poorly protected by IL-12, whereas IL-10-deficient mice were protected. We conclude that administration of IL-12 aborts disease by curtailing development of uveitogenic effector T cells. The data are compatible with the interpretation that IL-12 induces systemic hyperinduction of IFN-gamma, causing activation of iNOS and production of NO, which mediates protection at least in part by triggering Bcl-2 regulated apoptotic deletion of the antigen-specific T cells as they are being primed.

Animals↗
PubMed1999

Identification of genomic regions controlling experimental autoimmune uveoretinitis in rats.

The present study attempts to identify specific genetic loci contributing to experimental autoimmune uveoretinitis (EAU) susceptibility in F2 progeny of resistant Fischer (F344/N) and susceptible Lewis (LEW/N) inbred rats. F2 progeny of F344/N x LEW/N inbred rats were immunized with the R16 peptide of interphotoreceptor retinoid-binding protein (IRBP). A genome-wide scan was conducted using 125 simple sequence length polymorphism markers in selected F2 animals that developed severe eye disease or remained unaffected to identify phenotype:genotype co-segregation. The F2 population (n = 1287) demonstrated a wide range of histologically assessed EAU scores (assessed on a scale of 0-4). The disease incidence and severity were not consistent with a simple Mendelian inheritance model. Of the F2 hybrid rats, 60% developed EAU, implying the existence of a potent susceptibility locus with incomplete penetrance associated with the LEW genome or a more complex polygenic model of inheritance. Two genomic regions, on chromosomes 4 and 12, showed strong genetic linkage to the EAU phenotype (P < 0.0016), suggesting the presence of susceptibility loci in these chromosomal regions. In conclusion, we have identified two genomic candidate intervals from D4Arb8 to D4Mit17 on chromosome 4 and from the chromosome end to D12Arb8 on chromosome 12, that appear to influence EAU susceptibility in LEW/F344 rats. Further analysis of these genomic regions may lead to identification of the susceptibility genes and to characterization of their function.

Animals↗
PubMed1999

Autoimmunity to a pathogenic retinal antigen begins as a balanced cytokine response that polarizes towards type 1 in a disease-susceptible and towards type 2 in a disease-resistant genotype.

Susceptible, but not resistant, strains of rodents immunized for induction of experimental autoimmune uveitis (EAU) with the uveitogenic protein interphotoreceptor retinoid-binding protein (IRBP) exhibit a type 1 response at the time of disease expression. Here we investigate the evolution of this response using the prototypic EAU-susceptible and EAU-resistant mouse strains, B10.A and BALB/c. Disease severity and IRBP-specific responses (proliferation, cytokines and antibody isotypes) were evaluated 7, 14 and 21 days after uveitogenic immunization. B10.A mice initially exhibited an IgG1-dominated antibody response, and their lymph node cells produced IL-4 and IL-5 in addition to IFN-gamma. On day 14 and 21, however, the IgG2a isotype became predominant, and the primed lymph node cells produced mainly IFN-gamma and IL-12. B10.A mice developed EAU before day 14. BALB/c mice initially produced IL-12 and IFN-gamma in addition to IL-5, IL-4 and IL-10. At later time points IL-12 and IFN-gamma production diminished, and IL-4, IL-5 and IL-10 increased. An IgG1-dominated antibody response was maintained throughout. BALB/c mice failed to develop EAU even at day 21. Thus, both susceptible and resistant genotypes initially mount a balanced, type 0-like cytokine response to a uveitogenic challenge, that subsequently polarizes towards type 1 in the susceptible strain and towards type 2 in the resistant strain.

Animals↗
PubMed1999

Protective effect of the type IV phosphodiesterase inhibitor rolipram in EAU: protection is independent of IL-10-inducing activity.

PURPOSE: Experimental autoimmune uveoretinitis (EAU) is a cell-mediated model of retinal autoimmunity that is negatively regulated by interleukin (IL)-10. The antidepressant drug rolipram, a type IV phosphodiesterase inhibitor, enhances IL-10 production by monocyte/macrophages. The effect of rolipram on induction of EAU and its associated immunologic responses was investigated. METHODS: Mice were challenged for EAU induction by immunization with the retinal antigen interphotoreceptor retinoid-binding protein (IRBP) or by adoptive transfer of uveitogenic T cells and were treated with rolipram. EAU severity and immunologic responses to IRBP were analyzed. In addition, the effect of rolipram added to the culture on antigen-driven responses of primed lymph node cells was tested. RESULTS: Rolipram treatment from days -1 to 7 after immunization (afferent phase) was not protective, but severity of EAU was reduced to 50% by treatment from days 8 to 16 after immunization or when EAU was induced by adoptive transfer (efferent phase). Antigen-specific proliferation and interferon (IFN)-gamma production ex vivo by lymph node cells of protected mice were not reduced. However, the addition of rolipram directly to the culture suppressed IRBP-driven proliferation and IFN-gamma production by primed lymph node cells. Freshly explanted lymph node cells of treated mice showed inhibition of IFN-gamma mRNA but no parallel enhancement of IL-10 mRNA by quantitative polymerase chain reaction. Rolipram inhibited EAU in IL-10 knockout mice equally well compared with controls and suppressed their primed lymph node cells in culture. CONCLUSIONS: Rolipram appears to inhibit the expansion and effector function of uveitogenic T cells, raising the possibility that it may be useful for treatment of established disease. Contrary to expectations based on in vitro studies, the protective effects in vivo appear to be independent of IL-10. The observation that suppression of antigen-specific responses is demonstrable only in the physical presence of the drug suggests that, in a clinical setting, continuous administration of rolipram might be needed to sustain its therapeutic effect.

Adoptive Transfer↗
PubMed1999

Mice deficient in inducible nitric oxide synthase are susceptible to experimental autoimmune uveoretinitis.

PURPOSE: Nitric oxide (NO) is an important mediator of inflammatory tissue damage. The present study addresses the question whether inducible nitric oxide synthase (iNOS), and consequently the ability to upregulate NO, is required to effect the pathogenesis of experimental autoimmune uveoretinitis (EAU) in mice. METHODS: Mice with a homologous disruption of the iNOS gene (iNOS KO) were evaluated for their ability to develop EAU and associated cellular responses after immunization with the interphotoreceptor retinoid-binding protein. EAU was determined by histopathology 21 days after uveitogenic immunization, and antigen-specific cellular responses were assessed by delayed type hypersensitivity and lymphocyte proliferation. RESULTS: iNOS knockout (iNOS KO) mice developed EAU with scores similar to wild-type mice and exhibited good cellular responses to the immunizing antigen. CONCLUSIONS: A functional iNOS gene is not necessary for EAU pathogenesis. Therefore, upregulation of NO is not required to mediate autoimmune tissue damage in the eye.

Animals↗