To assess the role of sequestration in the maintenance of the immune privilege of the retina, retrovirally mediated gene transfer was used to express a defined, specific retinal autoantigen, rat soluble retinal Ag (S-Ag), in a systemic,... more
To assess the role of sequestration in the maintenance of the immune privilege of the retina, retrovirally mediated gene transfer was used to express a defined, specific retinal autoantigen, rat soluble retinal Ag (S-Ag), in a systemic, nonsequestered manner. In this study we report the stable, long term transduction of rat retinal S-Ag into PBMC. Tolerance to S-Ag was assayed by challenging the S-Ag chimeric animals with S-Ag peptides in CFA and monitoring the time course and severity of experimental autoimmune uveoretinitis (EAU). The resulting data showed a correlation between the incidence of S-Ag chimerism and the loss of susceptibility to EAU. The development of resistance to EAU induction supports the hypothesis that Ag sequestration contributes to retinal immune privilege.
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Recent studies revealing active mechanisms of immune privilege in neural tissues have diminished the putative role of passive tolerance. To examine the significance of Ag localization in the retina on immune privilege, the immune... more
Recent studies revealing active mechanisms of immune privilege in neural tissues have diminished the putative role of passive tolerance. To examine the significance of Ag localization in the retina on immune privilege, the immune responses of transgenic mice expressing high and low levels of β-galactosidase (β-gal) in the photoreceptor cells of the retina were compared with those of normal mice and those of mice expressing moderate levels of β-gal systemically. Immunization with β-gal induced experimental autoimmune uveoretinitis indistinguishable from that induced by known photoreceptor cell autoantigens, including destruction of photoreceptor cells, in transgenic mice with high level retinal expression. Retinal expression had no apparent effect on the immune responses to β-gal, showing that tolerance was not elicited by levels of retinal β-gal sufficient to serve as a target for autoimmune disease. Mice with systemic expression exhibited reduced lymphoproliferative responses follo...
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We have reported that Ia+ LEW rat corneal endothelial (CE) cells could not induce Ag-specific proliferation of MHC compatible T cell lines. Instead, the presence of CE cell monolayers inhibited T cell proliferation assays. We now report... more
We have reported that Ia+ LEW rat corneal endothelial (CE) cells could not induce Ag-specific proliferation of MHC compatible T cell lines. Instead, the presence of CE cell monolayers inhibited T cell proliferation assays. We now report on the effect of CE cells on IL-2 production, IL-2R expression, and IL-2 responsiveness of T cells. Ag-specific growth inhibition of the 1C3.4 T cell hybridoma was unaffected by the presence of CE cells but IL-2 production was suppressed by CE cells. Similar CE cell-mediated inhibition of IL-2 secretion was found with fresh splenic lymphocytes stimulated by Con A. Controls showed that neither CE cells nor their supernatant affected the CTLL cell response to rIL-2, allowing reliable measurement of IL-2 production. Further evidence that the block is at the level of IL-2 production was shown by the observation that IL-2R expression was up-regulated after TCR occupancy whether or not CE cells were present. Also, T cells expressing IL-2R were responsive t...
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Experimental autoimmune uveoretinitis (EAU) is a predominantly T cell-mediated autoimmune disease induced in susceptible animals by active immunization with human or bovine retinal S-Ag or by passive transfer of activated S-Ag or... more
Experimental autoimmune uveoretinitis (EAU) is a predominantly T cell-mediated autoimmune disease induced in susceptible animals by active immunization with human or bovine retinal S-Ag or by passive transfer of activated S-Ag or peptide-specific CD4+ T cells. During the course of studies aimed at the identification of T cell and B cell recognition sites in bovine and human S-Ag, a new potent uveitogenic region, located near the carboxy terminus of the molecule, was identified and characterized. Analysis of several synthetic peptides from this region showed that a 14 amino acid residue peptide, BSAg339-352, was highly uveitogenic when injected with adjuvants into Lewis rats. A uveitogenic T cell line, R737, was raised by in vitro selection of lymphocytes from animals immunized with peptide BSAg333-352. Northern blot analysis of mRNA from the R737 T cell line was positive for the rat homologs of murine V beta 8 and V alpha 2 T cell receptor gene probes. Whereas peptide BSAg339-352 de...
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Sera from guinea pigs and rabbits with and without experimental autoimmune uveitis (EAU) induced by immunization with retina, choroid, optic nerve, retinal rod outer segments (ROS) and purified bovine S-antigen were tested for the ability... more
Sera from guinea pigs and rabbits with and without experimental autoimmune uveitis (EAU) induced by immunization with retina, choroid, optic nerve, retinal rod outer segments (ROS) and purified bovine S-antigen were tested for the ability to immunoprecipitate 125I-labeled, detergent-solubilized bovine retinal proteins. The results demonstrate that three major protein antigens with m.w. of 50,000 (p50), 35,000 (p35) and 27,000 (p27) and several minor activities between 30,000 and 60,000 m.w. are recognized by antibodies from these animals. The p50 component was immunoprecipitated by sera from animals immunized with whole retina homogenate, the high speed supernatant of whole retina homogenate, ROS, and S-antigen, and has been identified as S-antigen in competition experiments. The p35 band appeared when sera were used that were raised against antigen preparations containing membrane-bound retinal protein, i.e., whole retina homogenate, ROS, and washed ROS, and thus appears to be an R...
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Previous analyses of T cell recognition sites on immunopathogenic neural autoantigens have demonstrated, using LEW rats, the functional dissociation of in vitro proliferative responses and the ability to actively induce autoimmune... more
Previous analyses of T cell recognition sites on immunopathogenic neural autoantigens have demonstrated, using LEW rats, the functional dissociation of in vitro proliferative responses and the ability to actively induce autoimmune diseases. In experimental autoimmune uveoretinitis, immunization of LEW rats with bovine retinal S-Ag reveals the presence of three immunodominant T cell recognition sites located in regions containing sequence differences between bovine and rat S-Ag. Immune responses of LEW rats to self (rat) and nonself (bovine and human) peptide homologues representing these three sites were compared. The immunodominant sequences of heterologous S-Ag were found to predict new pathogenic T cell recognition sites in the corresponding autologous rat sequence. Furthermore, in vitro proliferative responses to the pathogenic autologous sequences are dramatically diminished relative to the responses of lymphocytes raised to the non-self homologues. A pathogenic T cell line, R858, efficiently transferred disease, but was unresponsive to the autologous S-Ag peptide in proliferation assays. However, responses to autologous peptides were readily detected using nonirradiated splenic APC. Detection of responses to non-self peptides was independent of this radiosensitive Ag-presenting activity. The lack of in vitro proliferative responses to pathogenic autologous sequences by T cells bearing self-specific receptors, contrasted with the strong proliferation induced by non-self peptide homologues, suggests a mechanism of unresponsiveness to self.
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Purified bovine retinal S-antigen (50,000 m.w.) was treated with cyanogen bromide, producing seven major and several minor fragments. Six of the major and one of the minor components were isolated by reverse phase high performance liquid... more
Purified bovine retinal S-antigen (50,000 m.w.) was treated with cyanogen bromide, producing seven major and several minor fragments. Six of the major and one of the minor components were isolated by reverse phase high performance liquid chromatography. The peptides were characterized with respect to size by urea-SDS-gel electrophoresis, by amino acid composition, and by their ability to bind antibodies, raised in rabbits immunized with purified bovine S-antigen, in both competition and direct enzyme-linked immunosorbent assays. Four of the purified peptides were found, by the direct assay, to bind antibodies in immune sera raised to the intact antigen. Peptides that were negative, or only weakly bound, in the direct enzyme immunoassay were subsequently conjugated to a carrier, poly-L-Glu-Ala-Tyr, and were retested in the enzyme immunoassay in which a peptide of about 25 residues was also found to contain an antigenic determinant. The same five peptides were positive in the competition assays. Isolation of the peptides and gel electrophoresis under reducing and nonreducing conditions revealed that two of the peptides in the reaction mixture were joined by a disulfide linkage.
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Biochemistry, Chemistry, Immunology, Immunology of the Gut, Medicine, and 15 moreAnimals, Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis, Peptide, Cattle, Antibody, Chemical Precipitation, Immunoassay, Gel electrophoresis, Rabbits, Enzyme Linked Immunosorbent Assay, Antigens, Antigen, Autoantigens, Arrestin, and Photoreceptor cells
Mycoplasma arthritidis was demonstrated to incite experimental conjunctivitis and uveitis in Swiss Webster mice which have a known susceptibility to the arthritis customarily associated with infection by this mycoplasma. The initial... more
Mycoplasma arthritidis was demonstrated to incite experimental conjunctivitis and uveitis in Swiss Webster mice which have a known susceptibility to the arthritis customarily associated with infection by this mycoplasma. The initial symptom of ocular involvement was conjunctivitis, which appeared as early as 1 day after intravenous injection with viable culture concentrates of M. arthritidis. By day 2, histological analysis showed intraocular localized inflammatory reactions that were confined primarily to the anterior portion of the uvea and produced results which were compatible with those seen in iridocyclitis. Serological assays of the titer and the class of antibodies involved in the early humoral immune response to infection confirmed the predominance of immunoglobulin G (IgG) concentrations over IgM concentrations that was described by others (Cole et al., Infect. Immun. 4:431-440, 1971) and revealed significant titers of the IgG2a and IgG2b subclasses of complement-fixing an...
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ABSTRACT Several retinal diseases, including retinitis pigmentosa (RP) and other inherited retinal diseases, age related macular degeneration (ARMD), inflammatory diseases and infections, diabetic retinopathy, and retinopathy of... more
ABSTRACT Several retinal diseases, including retinitis pigmentosa (RP) and other inherited retinal diseases, age related macular degeneration (ARMD), inflammatory diseases and infections, diabetic retinopathy, and retinopathy of prematurity (ROP), result in severe visual loss from the degeneration of retinal photoreceptors, neurons and ganglion cells. Although some amphibians and fish display the capacity for retinal growth and regeneration after birth from cells at the ciliary margin(1), adult mammalian retina ceases to grow shortly 2 after birth and does not regenerate. The loss of these cells from disease, injury or inflammation in the mammalian retina is particularly detrimental due to the absence of regeneration. No effective long-term treatments for retinal/photoreceptor degeneration or damage exist. Collectively, over 2 million residents of the US alone are currently affected by these diseases. Many of these diseases are slowly progressive with a continual, increasing loss of vision. The ability to regenerate and repair damage to critical, terminally-differentiated tissues is at the center of hopes for the therapeutic use of stem cells. Embryonic stem (ES)(2) cells have unlimited self renewal and multipotent differentiation potential. Conversely, tissue-specific progenitor cells have less self-renewal ability than ES cells and, although they differentiate into multiple lineages, are not multipotent(3-8). Stem or progenitor cells have been identified in many tissues, including some collected from adults, and include hematopoietic(9, 10), neural(11, 12), gastrointestinal(13), epidermal(14), hepatic(15) and mesenchymal stem cells(16-18). Their availability provides some advantages.
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Immunoproteasomes contain replacements for the three catalytic subunits of standard proteasomes. In most cells, oxidative stress and proinflammatory cytokines are stimuli that lead to elevated production of immunoproteasomes. Immune... more
Immunoproteasomes contain replacements for the three catalytic subunits of standard proteasomes. In most cells, oxidative stress and proinflammatory cytokines are stimuli that lead to elevated production of immunoproteasomes. Immune system cells, especially antigen-presenting cells, express a higher basal level of immunoproteasomes. A well-described function of immunoproteasomes is to generate peptides with a hydrophobic C terminus that can be processed to fit in the groove of MHC class I molecules. This display of peptides on the cell surface allows surveillance by CD8 T cells of the adaptive immune system for pathogen-infected cells. Functions of immunoproteasomes, other than generating peptides for antigen presentation, are emerging from studies in immunoproteasome-deficient mice, and are complemented by recently described diseases linked to mutations or single-nucleotide polymorphisms in immunoproteasome subunits. Thus, this growing body of literature suggests a more pleiotropic...
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Recent studies revealing active mechanisms of immune privilege in neural tissues have diminished the putative role of passive tolerance. To examine the significance of Ag localization in the retina on immune privilege, the immune... more
Recent studies revealing active mechanisms of immune privilege in neural tissues have diminished the putative role of passive tolerance. To examine the significance of Ag localization in the retina on immune privilege, the immune responses of transgenic mice expressing high and low levels of beta-galactosidase (beta-gal) in the photoreceptor cells of the retina were compared with those of normal mice and those of mice expressing moderate levels of beta-gal systemically. Immunization with beta-gal induced experimental autoimmune uveoretinitis indistinguishable from that induced by known photoreceptor cell autoantigens, including destruction of photoreceptor cells, in transgenic mice with high level retinal expression. Retinal expression had no apparent effect on the immune responses to beta-gal, showing that tolerance was not elicited by levels of retinal beta-gal sufficient to serve as a target for autoimmune disease. Mice with systemic expression exhibited reduced lymphoproliferati...
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To design a new model of proliferative vitreoretinopathy (PVR) that would not rely on the addition of exogenous cells. The release of endogenous cells from surrounding attachments seems to be an early event in the pathogenesis of PVR.... more
To design a new model of proliferative vitreoretinopathy (PVR) that would not rely on the addition of exogenous cells. The release of endogenous cells from surrounding attachments seems to be an early event in the pathogenesis of PVR. Because the proteolytic enzyme dispase dissociates tissues, the hypothesis was that an intraocular injection of dispase could trigger events that would cause PVR. The requirement for a surgical retinal break at the time of dispase injection was also examined. One eye of Dutch Belted rabbits was injected with 0.003 U to 1.0 U dispase in the subretinal space or vitreous cavity. Control rabbits received a saline injection. An intentional retinal tear was created in animals in some groups. Observations were made for at least 10 weeks after surgery. Proliferative vitreoretinopathy developed in response to subretinal or intravitreal dispase, with or without creation of a controlled retinal break. Increased severity of PVR correlated with increasing doses of ...
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This study was designed to determine whether Alamar blue could be used to evaluate corneal endothelial cell viability in vitro. Alamar blue incorporates a proprietary redox indicator that changes color in response to metabolic activity.... more
This study was designed to determine whether Alamar blue could be used to evaluate corneal endothelial cell viability in vitro. Alamar blue incorporates a proprietary redox indicator that changes color in response to metabolic activity. Primary rabbit endothelial cells were subcultured on 96-well plates at densities ranging from 1,250 to 40,000 cells per well. After 12 hours' incubation, Alamar blue was added to each well and absorbance measured hourly from 1 to 9 hours. Sodium azide-killed cells were used as a control. Alamar blue conversion was also compared with [3H]-thymidine incorporation in the presence or the absence of mitomycin C. Alamar blue reduction demonstrated endothelial cell viability at all cell concentrations compared with that in killed-cell controls. The reduction varied proportionately with cell number and time, showing clearly significant differences. Conversely, [3H]-thymidine uptake demonstrated minimal DNA synthesis and little or no ability to distinguis...
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The hypothesis that uveal vessels absorb fluid was tested by measuring the albumin in extravascular uveal tissues and in plasma. From these results the effective albumin concentration was calculated in both rabbits and monkeys. Three... more
The hypothesis that uveal vessels absorb fluid was tested by measuring the albumin in extravascular uveal tissues and in plasma. From these results the effective albumin concentration was calculated in both rabbits and monkeys. Three separate methods were used to measure uveal albumin, and the results of these were compared. In method 1, the intravenous fluorescein isothiocyanate (FITC)-albumin concentration found in the uvea 5 min after injection (intravascular tracer) was subtracted from that found 2 hr after injection (intravascular plus extravascular tracer) to determine the extravascular albumin concentration. In method 2, intravenous FITC-albumin was followed by vascular washout after a 2-hr equilibration period to determine extravascular uveal albumin. In method 3, the endogenous extravascular albumin concentration of uveal tissues was measured with an enzyme-linked immunosorbent assay (ELISA) after vascular washout. The effective albumin concentration was determined by divid...
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ABSTRACT
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ABSTRACT The expression of Fas ligand (FasL) in the eye has been proposed to be an important component of ocular immune privilege. Since the unusually favorable outcome of corneal transplantation is thought to result from the immune... more
ABSTRACT The expression of Fas ligand (FasL) in the eye has been proposed to be an important component of ocular immune privilege. Since the unusually favorable outcome of corneal transplantation is thought to result from the immune privilege of the eye, examination of the function of FasL on corneal allografts would be a test of that hypothesis. To investigate the role of Fas-FasL interaction in corneal allografts, orthotopic corneal transplantation was performed using C57BL/6 (B6, FasL+) and B6-gld (FasL-) mice as cornea donors and BALB/c mice as recipients. The rejection rate of B6-gld grafts (FasL- group) was compared with that of normal B6 control corneas. The rejection rate at the final observation (8 weeks) in the FasL- group (89%) was significantly higher than in the FasL+ control group (47%). FasL expression was found on the corneal endothelium by staining with anti-FasL monoclonal antibodies. The TdT-mediated dUTP nick-end labeling assay revealed that apoptotic cells were attached to the endothelium in the control group but not in the FasL- groups. Apoptosis of infiltrating cells on the corneal endothelium resulting from Fas-FasL interaction plays an important role in the high success rate of corneal transplantation.
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Engineering, Physics, Chemistry, Biology, Cell Biology, and 15 moreMedicine, Retinal Pigment Epithelium, Multidisciplinary, Signal Transduction, Mice, Animals, NF-kappa B, Transcription Factor, PLoS one, Immune system, Tumor necrosis factor-alpha, Cysteine endopeptidases, NF κB, NFkB, and Gene Expression Regulation
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Background: Thymic expression of a photoreceptor cell antigen, interphotoreceptor retinoid-binding protein, is known to generate regulatory T cells (Treg) that prevent spontaneous autoimmune disease of the retina. However, the... more
Background: Thymic expression of a photoreceptor cell antigen, interphotoreceptor retinoid-binding protein, is known to generate regulatory T cells (Treg) that prevent spontaneous autoimmune disease of the retina. However, the contribution of other endogenous, tissue-specific antigens (Ags) expressed in the retina to the generation of Treg is uncertain. Methods: Transgenic mice that express β-galactosidase (β-gal) in photoreceptor cells, together with β-gal-specific T cell receptor transgenic mice, were used to study the induction of Treg in vivo. Results: Transgenic expression of β-gal on the arrestin promoter led to a spontaneous immunoregulatory response that inhibited the development of immune responses to β-gal. The regulation was transferred by CD3+4+25+ Treg. Several strategies were then used to show that β-gal expressed in the retina supported spontaneous, thymus-independent Treg development. The endogenous Treg also differed from the Treg induced by Ag inoculation into the ...
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As new Ag-specific and non-Ag-specific mechanisms contributing to ocular immune privilege are revealed, the relevance of old paradigms properly comes into question. My lab has a particular interest in the immune privilege of the retina.... more
As new Ag-specific and non-Ag-specific mechanisms contributing to ocular immune privilege are revealed, the relevance of old paradigms properly comes into question. My lab has a particular interest in the immune privilege of the retina. While the presence of active mechanisms of tolerance, such as immune deviation, is now well-established, we propose that sequestration provides the first line of immune privilege in the retina. When it fails, active, inducible mechanisms provide backup to protect the integrity of the retina and vision. Some of the observations that led to our hypotheses and their supporting experiments are discussed below.
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Immunology, Autoimmunity, Medicine, Humans, Animals, and 4 moreRetina, Immune system, Immune Tolerance, and Autoantigens
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Neurobiology Of Disease, Biology, Cell Biology, Medicine, Dendritic Cells, and 15 moreOptic Nerve, Mice, Animals, Microglia, Retina, Reaction Time, Light, Dendritic cell, Green Fluorescent Protein, Clinical Sciences, MHC class II, Neuronal Death, Neurosciences, Optic Nerve Injuries, and photic stimulation
The type III variant of the epidermal growth factor receptor (EGFRvIII) mutation is present in 20-25% of patients with glioblastoma multiforme (GBM). EGFRvIII is not expressed in normal tissue and is therefore a suitable candidate antigen... more
The type III variant of the epidermal growth factor receptor (EGFRvIII) mutation is present in 20-25% of patients with glioblastoma multiforme (GBM). EGFRvIII is not expressed in normal tissue and is therefore a suitable candidate antigen for dendritic cell (DC) based immunotherapy of GBM. To identify the antigenic epitope(s) that may serve as targets for EGFRvIII-specific cytotoxic T lymphocytes (CTLs), the peptide sequence of EGFRvIII was screened with two software programs to predict candidate epitopes restricted by the major histocompatibility complex class I subtype HLA-A0201, which is the predominant subtype in most ethnic groups. Three predicted peptides were constructed and loaded to mature human DCs generated from peripheral blood monocytes. Autologous CD8+ T cells were stimulated in vitro with the EGFRvIII peptide-pulsed DCs. One of the three peptides was found to induce EGFRvIII-specific CTLs as demonstrated by IFN-gamma production and cytotoxicity against HLA-A0201+ EGFRvIII transfected U87 glioma cells. These results suggest that vaccination with EGFRvIII peptide-pulsed DCs or adoptive transfer of in vitro elicited EGFRvIII-specific CTLs by EGFRvIII peptide-pulsed DCs are potential approaches to the treatment of glioma patients.
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Activated T cells recognize Ag in the retina, an immune privileged tissue, and may mediate autoimmune disease. In contrast, this report asks if resting, Ag-specific CD4(+) CD44(+) T cells can recognize Ag expressed in the retina. As a... more
Activated T cells recognize Ag in the retina, an immune privileged tissue, and may mediate autoimmune disease. In contrast, this report asks if resting, Ag-specific CD4(+) CD44(+) T cells can recognize Ag expressed in the retina. As a probe for Ag, 3E9 T cells specific for an immunodominant epitope of beta-galactosidase (beta-gal) were transferred to transgenic (Tg) mice expressing beta-gal in retinal photoreceptor cells, or to ROSA26 mice which express beta-gal widely. The survival, phenotype, and responsiveness of transferred 3E9 T cells were unaffected by the presence of retinal beta-gal, but altered by recognition of beta-gal in the ROSA26 mice. Inoculation or induction of activated T cells with specificity for this epitope produced autoimmune uveoretinitis, showing that the retinal beta-gal is expressed at immunologically significant levels. We conclude that sequestration provides a substantial barrier to recognition of Ag in quiet retina, and that insufficient Ag leaves the retina for detectable immune recognition outside of the retina.
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T cell adoptive transfer models of autoimmune disease have been used in conjunction with radiation/bone marrow chimeras to define the minimal requirements for antigen (Ag) recognition. In models with central nervous system Ags, major... more
T cell adoptive transfer models of autoimmune disease have been used in conjunction with radiation/bone marrow chimeras to define the minimal requirements for antigen (Ag) recognition. In models with central nervous system Ags, major histocompatibility complex (MHC) class II compatibility achieved by grafting F1 bone marrow into parental recipients was reported to be necessary and sufficient for transfer of CD4 T cell-mediated experimental autoimmune encephalomyelitis. Bone marrow-derived, perivascular microglia are now widely regarded to play a critical role in the expression of experimental autoimmune diseases of the nervous system. Similar results might be expected in the experimental autoimmune uveoretinitis model, as retina is an extension of the brain. Using an allogeneic Ag-presenting cell (APC) adoptive transfer strategy, it was found that resident APC were not essential and that their replacement with MHC-compatible cells by bone marrow-grafting techniques was not necessary...
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Immunology, Biology, Infectious Diseases, Medicine, Biological Sciences, and 15 moreToxic shock syndrome, Bacterial Toxins, Mice, Enterotoxins, Female, Animals, Staphylococcus aureus, Immunosuppression, Cyclosporine, Infectious, T lymphocytes, Superantigen, Rabbits, Immunosuppressive Agents, and Medical and Health Sciences
Although several observations show local T cell recognition of retinal Ag, there has been no direct demonstration that the APC were retinal derived, rather than recruited. In this study, CD45+ cells isolated from immunologically quiescent... more
Although several observations show local T cell recognition of retinal Ag, there has been no direct demonstration that the APC were retinal derived, rather than recruited. In this study, CD45+ cells isolated from immunologically quiescent murine retina were tested in vitro for functional evidence of Ag presentation to naive and Ag-experienced CD4 T cells specific for β-galactosidase. Because CD45+ cells from brain have been reported to be efficient APC, they were included for comparison. Measures of activation included changes in CD4, CD25, CD44, CD45RB, CD62L, CD69, caspase-3 activation, CFSE dilution, size, number of cells recovered, and cytokine production. Retinal CD45+ cells gave no evidence of Ag-dependent TCR ligation in naive T cells, unlike splenic APC and CD45+ cells from brain, which supported potent responses. Instead, addition of retinal CD45+ cells to cocultures of naive 3E9 T cells plus splenic APC reduced the yield of activated T cells and cytokine production by limi...
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The contribution of peripheral expression of tissue-specific CNS Ags to the generation of tolerance is uncertain. To study this question, we examined mice transgenic (Tg) for expression of β-galactosidase (βgal) on the retinal... more
The contribution of peripheral expression of tissue-specific CNS Ags to the generation of tolerance is uncertain. To study this question, we examined mice transgenic (Tg) for expression of β-galactosidase (βgal) on the retinal photoreceptor cell arrestin promoter, in conjunction with TCR Tg mice producing CD4+ T cells specific for βgal (βgalTCR). Several strategies were used to test the hypothesis that βgal expressed in the retina supported thymus-independent tolerance and regulatory T cell development. Retinal expression generated an immunoregulatory response that depressed development of immune responses to βgal following systemic immunization with βgal. This regulation was transferable to naive mice by CD3+4+25+ T cells from naive retinal βgal+ donors. Experiments that removed the βgal+ retina by enucleation showed that subsequent development of a regulatory response was lost. Adoptive transfer of CD25− βgalTCR T cells into retinal βgal Tg mice on the Rag−/− background led to reg...
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Interest in the identities, properties, functions, and origins of local APC in CNS tissues is growing. We recently reported that dendritic cells (DC) distinct from microglia were present in quiescent retina and rapidly responded to... more
Interest in the identities, properties, functions, and origins of local APC in CNS tissues is growing. We recently reported that dendritic cells (DC) distinct from microglia were present in quiescent retina and rapidly responded to injured neurons. In this study, the disease-promoting and regulatory contributions of these APC in experimental autoimmune uveoretinitis (EAU) were examined. Local delivery of purified, exogenous DC or monocytes from bone marrow substantially increased the incidence and severity of EAU induced by adoptive transfer of activated, autoreactive CD4 or CD8 T cells that was limited to the manipulated eye. In vitro assays of APC activity of DC from quiescent retina showed that they promoted generation of Foxp3+ T cells and inhibited activation of naive T cells by splenic DC and Ag. Conversely, in vitro assays of DC purified from injured retina demonstrated an enhanced ability to activate T cells and reduced induction of Foxp3+ T cells. These findings were suppor...
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Extrathymically derived regulatory T cells (iTregs) protect against autoimmunity to tissue-specific Ags. However, whether Ag-specific iTreg generation and function is limited to secondary lymphoid tissue or whether it can occur within the... more
Extrathymically derived regulatory T cells (iTregs) protect against autoimmunity to tissue-specific Ags. However, whether Ag-specific iTreg generation and function is limited to secondary lymphoid tissue or whether it can occur within the tissue-specific local environment of the cognate Ag remains unresolved. Mice expressing β-galactosidase (βgal) on a retina-specific promoter (βgal mice) in conjunction with mice expressing GFP and diphtheria toxin (DTx) receptor (DTR) under control of the Foxp3 promoter, and βgal-specific TCR transgenic (BG2) mice were used to examine this question. Local depletion (ocular DTx), but not systemic depletion (i.p. DTx), of βgal-specific iTregs enhanced experimental autoimmune uveoretinitis induced by activated βgal-specific effector T cells. Injections of small amounts of βgal into the anterior chamber of the eye produced similar numbers of βgal-specific iTregs in the retina whether the mouse was depleted of pre-existing, circulating Tregs. Taken toge...
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Autoreactive T cell hybridomas specific for pathogenic peptides of retinal S-Ag require a novel radiosensitive APC activity for IL-2 secretion that is distinct from Ag presentation by MHC class II. Antigen-dependent IL-2 secretion by... more
Autoreactive T cell hybridomas specific for pathogenic peptides of retinal S-Ag require a novel radiosensitive APC activity for IL-2 secretion that is distinct from Ag presentation by MHC class II. Antigen-dependent IL-2 secretion by self-reactive hybridomas was much more efficient with splenic APC than with thymic APC, although both provided similar levels of hybridoma TCR occupancy as measured by activation-induced cell death. Furthermore, thymic APC did stimulate IL-2 secretion by a non-self reactive hybridoma. To test the hypothesis that this activity was provided by a distinct cell population, fractionated splenocytes were tested for their ability to present Ag to these hybridomas. The most potent Ag presentation for IL-2 secretion was found to segregate with low-density, B cell-enriched fractions while adherent cells, or purified T cells were unable to support IL-2 production. Together with previous results, the data show that antigen presentation leading to IL-2 secretion by these autoreactive T cell hybridomas requires activated B cells, whereas TCR occupancy can be provided by several APC subsets.
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Immunology, Flow Cytometry, Biology, Apoptosis, Medicine, and 15 moreBiological Sciences, Animals, Antigen Processing, Antigen Presentation, Bystander Effect, Caspase, Cytotoxic Activity, CTL, Major histocompatibility complex, Antigen, Antigen presenting cells, Interferon gamma, coculture techniques, Blood Retinal Barrier, and Medical and Health Sciences
The retina is a well-known immune-privileged tissue in the eye. Gene therapy and transgenic strategies have been taken to explore the relationship between the immune system and retinal antigens. Retroviruses were used to express... more
The retina is a well-known immune-privileged tissue in the eye. Gene therapy and transgenic strategies have been taken to explore the relationship between the immune system and retinal antigens. Retroviruses were used to express retina-specific antigens or fragments systemically, leading to an antigen-specific loss of susceptibility to autoimmune disease. Transgenic strategies used a neo self-antigen, beta-galactosidase, or a known retinal antigen, interphotoreceptor retinoid-binding protein, to show that immune recognition of antigen by mice, which express solely in the retina, is not detectably different than that of mice that don't express this antigen. Together, these studies show that antigens expressed solely in the retina do not appear to be seen by the immune system, demonstrating that sequestration contributes to the lack of antigen recognition and absence of tolerance. Provision of these antigens outside of the retina provides the opportunity for development of peripheral tolerance, protection from autoimmunity, and potential therapies.
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T cell hybridomas were generated from a LEW rat T cell line specific for the uveitogenic peptide bov-B1 of bovine retinal S-antigen. Using these autoreactive hybridomas, IL-2 production and activation-induced cell death (AICD) were... more
T cell hybridomas were generated from a LEW rat T cell line specific for the uveitogenic peptide bov-B1 of bovine retinal S-antigen. Using these autoreactive hybridomas, IL-2 production and activation-induced cell death (AICD) were dissociated as outcomes of activation. The self-reactive hybridomas secrete IL-2 and undergo AICD in response to antigen presented by non-irradiated syngeneic splenocytes, whereas antigen presentation by irradiated splenocytes induced only AICD. IL-2 production by a non-self reactive hybridoma was unaffected by irradiation of the APC. Pretreatment of the APC with phorbol ester or lipopolysaccharide and IL-4 protected their ability to induce IL-2 secretion after gamma-irradiation. Although the co-stimulation-blocking reagent CTLA-4-Ig mimicked the effect of gamma-irradiation by preventing IL-2 secretion but not AICD, B7 expression on the APC was not radiosensitive, nor did co-stimulation, provided 'in trans' with a B7-expressing third-party cell, reconstitute antigen-specific hybridoma IL-2 secretion in response to irradiated APC. In summary, the data show that IL-2 secretion and AICD of a self-reactive T cell hybridoma can be dissociated as consequences of TCR occupancy in the presence of a functional co-stimulatory signal. It is proposed that the signals producing these events are transduced through the TCR-CD3 complex alone and reflect the differential outcomes of high- and low-affinity interactions.