Organ-resident, nonlymphoid cells suppress proliferation of autoimmune T-helper lymphocytes.

Local presentation of autoantigen by organ-resident cells inappropriately expressing Ia determinants has been implicated in organ-specific autoimmunity. Experimental autoimmune uveoretinitis, induced in rats by immunization with retinal soluble antigen, is used as a model of organ-specific autoimmunity. In an in vitro system derived from this model, uveitogenic rat T-helper lymphocytes specific to the retinal soluble antigen, or control T-helper lymphocytes reactive to the purified protein derivative of tuberculin, were cocultured with Ia-expressing syngeneic retinal glial cells (Müller cells) in the presence of specific antigen. Antigen presentation was not apparent under ordinary culture conditions, and the Müller cells profoundly suppressed the proliferative response of primed T-helper lymphocytes to antigen presented on conventional antigen-presenting cells, as well as their subsequent interleukin-2 (IL-2)-dependent expansion. Suppression of proliferation was accompanied by inhibition of IL-2 production in response to antigen, as well as by reduction in high-affinity IL-2 receptor expression, and proceeded via a contact-dependent mechanism. These results suggest a role for locally acting suppression mechanisms in immune regulation and maintenance of tissue homeostasis.

Interleukin-2 treatment potentiates induction of oral tolerance in a murine model of autoimmunity.

The present study addresses the feasibility of potentiating oral tolerance by immunomanipulation, using the murine model of experimental autoimmune uveoretinitis (EAU) induced by immunization with the retinal antigen interphotoreceptor retinoid binding protein (IRBP). Three feedings of 0.2 mg IRBP every other day before immunization did not protect against EAU, whereas a similar regimen of five doses was protective. However, supplementing the nonprotective 3x regimen with as little as one injection of 1,000 U of human recombinant interleukin-2 (IL-2) resulted in disease suppression that was equal to that of the protective 5x regimen. The protective effect was maintained across a range of IL-2 doses and times of administration; none of the IL-2 regimens tested resulted in disease enhancement. Peyer's Patch cells of 3x-fed and IL-2-treated mice showed greatly increased production of TGF-beta, IL-4, and IL-10 compared with animals given the nonprotective 3x regimen and to animals given the protective 5x regimen. We propose that IL-2 treatment enhances protection from EAU at least in part by stimulating production of antiinflammatory cytokines by regulatory cells in Payer's Patches. Moreover, the observed lymphokine production patterns suggest that whereas protection induced by the 3x + IL-2 regimen is likely to involve antiinflammatory cytokines, protection induced by the 5x regimen might involve anergy or deletion of the uveitogenic T cells. These results could have practical implications for use of IL-2 as a safe and effective way of potentiating oral tolerance.

Cyclosporin a. Inhibition of experimental autoimmune uveitis in Lewis rats.

Cyclosporin A (CS-A), a selective inhibitor of T lymphocytes, is reported here to prevent S antigen (S-Ag) induced uveitis in Lewis rats. The S-Ag, found in all mammalian retinas, is uveitogenic under experimental conditions and patients with certain uveitic entities demonstrate cell mediated responses to this antigen. Daily treatment with CS-A (10 mg/kg) begun on the same day as S-Ag immunization totally inhibited the development of the uveitis in this experimental autoimmune model. Moreover a greater CS-A dose (40 mg/kg) efficiently prevented the disease process when therapy was started 7 d after S-Ag immunization. Anti-S-Ag antibody titers were observed to be similar in rats either protected or not protected with CS-A. Our data support strongly the need for T cell participation in this disease model. Since ocular inflammatory disease is an important cause of visual impairment, the data further suggest that CS-A may be useful in the treatment of patients with intractable uveitis.

Bromocriptine and low dose cyclosporine in the treatment of experimental autoimmune uveitis in the rat.

The immunologic effects of bromocriptine and low dose cyclosporine on experimental autoimmune uveitis (EAU) induced in Lewis rats by S-antigen immunization were studied. Rats treated with a sub-optimal dose (low dose) of cyclosporine (2 mg/kg per d), bromocriptine (1.8 mg/kg per d), or both drugs were compared with untreated rats in regard to the development of EAU, lymphocyte proliferative responses, and anti-S-antigen serum antibodies. Bromocriptine alone decreased the incidence of EAU only in female rats (P less than 0.01), did not effect the lymphocyte proliferative response, but did significantly decrease antibody titers in both males (P less than 0.004) and females (P less than 0.0005). Low dose cyclosporine also partially decreased the incidence of EAU in female rats, but did not decrease antibody titers or lymphocyte proliferative responses. Bromocriptine plus low-dose cyclosporine led to more marked decreases in the incidence of EAU and anti-S-antigen antibody titers as well as in the lymphocyte proliferative assay (P less than 0.01 for males, P less than 0.0005 for females). This study suggests that bromocriptine can enhance the immunosuppression of low dose cyclosporine.

Phase I and pharmacokinetic study of farnesyl protein transferase inhibitor R115777 in advanced cancer.

PURPOSE: To determine the maximum-tolerated dose, toxicities, and pharmacokinetic profile of the farnesyl protein transferase inhibitor R115777 when administered orally bid for 5 days every 2 weeks. PATIENTS AND METHODS: Twenty-seven patients with a median age of 58 years received 85 cycles of R115777 using an intrapatient and interpatient dose escalation schema. Drug was administered orally at escalating doses as a solution (25 to 850 mg bid) or as pellet capsules (500 to 1300 mg bid). Pharmacokinetics were assessed after the first dose and the last dose administered during cycle 1. RESULTS: Dose-limiting toxicity of grade 3 neuropathy was observed in one patient and grade 2 fatigue (decrease in two performance status levels) was seen in four of six patients treated with 1,300 mg bid. The most frequent clinical grade 2 or 3 adverse events in any cycle included nausea, vomiting, headache, fatigue, anemia, and hypotension. Myelosuppression was mild and infrequent. Peak plasma concentrations of R115777 were achieved within 0.5 to 4 hours after oral drug administration. The elimination of R115777 from plasma was biphasic, with sequential half-lives of about 5 hours and 16 hours. There was little drug accumulation after bid dosing, and steady-state concentrations were achieved within 2 to 3 days. The pharmacokinetics were dose proportional in the 25 to 325 mg/dose range for the oral solution. Urinary excretion of unchanged R115777 was less than 0.1% of the oral dose. One patient with metastatic colon cancer treated at the 500-mg bid dose had a 46% decrease in carcinoembryonic antigen levels, improvement in cough, and radiographically stable disease for 5 months. CONCLUSION: R115777 is bioavailable after oral administration and has an acceptable toxicity profile. Based upon pharmacokinetic data, the recommended dose for phase II trials is 500 mg orally bid (total daily dose, 1, 000 mg) for 5 consecutive days followed by 9 days of rest. Studies of continuous dosing and studies of R115777 in combination with chemotherapy are ongoing.

Enhancing effect of cyclosporins A and G on bone marrow colony formation.

The development of the number of colonies (cell colony-forming units, CFU-C) in soft agar from normal mouse bone marrow (BM) cells was enhanced 60% when total bone marrow cells (BMC) were preincubated for 1 h with either cyclosporin A (CsA) or cyclosporin G (CsG) before plating. Using cell fractionation techniques we found that the removal of macrophages enhanced CFU-C in noncyclosporin-treated BM and that cyclosporins mediated an additional enhancing effect. A similar enhancing effect on CFU-C in noncyclosporin-treated BM was obtained by depleting it of total T cells or Lyt-2.2+ cells. However, CFU-C growth in the residual BM population was no longer enhanced by cyclosporin. Conversely, removal of Lyt-1.2+ cells did not enhance CFU-C in noncyclosporin-treated BM, but the CFU-C in this population were enhanced by cyclosporin treatment. These results suggest that CsA and CsG can increase the cloning efficiency of normal mouse BMC, possibly by inhibiting an endogenous Lyt-2.2+ suppressor cell.

Retrovirus-mediated gene transfer and expression of human ornithine delta-aminotransferase into embryonic fibroblasts.

Ornithine delta aminotransferase (OAT) is a nuclear-encoded mitochondrial matrix enzyme that catalyzes the reversible transamination of ornithine to glutamate semialdehyde. In humans, genetic deficiency of OAT results in gyrate atrophy of the choroid and retina, a blinding chorioretinal degeneration usually beginning in late childhood. This disorder has been shown to be autosomal recessive, and is often caused by missense, nonsense, and/or frameshift mutations in the OAT gene. With the view of applying gene therapy, a Moloney murine leukemia virus (MoMLV)-based recombinant retrovirus vector has been constructed. The human OAT cDNA was placed under the control of the enhancer-promoter regulatory elements derived from the MoMLV long terminal repeat (LTR). The construct was transfected into the retroviral packaging cell lines GP + E - 86 and psi CRIP to produce virus particles. Supernatant from these OAT retrovirus producer cell lines were used to transduce mouse C57B1/6 embryonal fibroblasts. We showed that the recombinant retrovirus transfers the OAT gene to the recipient cells, which produce an OAT RNA transcript when analyzed by Northern blot. Western blot analysis and enzymatic assays confirmed the presence of an OAT polypeptide that has a high enzymatic activity in the transduced cell lines, even after a long period of time in vitro.

Retrovirus-mediated gene transfer of ornithine-delta-aminotransferase into keratinocytes from gyrate atrophy patients.

Gyrate atrophy is a progressive blindness associated with deficiency of ornithine aminotransferase (OAT). The strategy of using an autologous keratinocyte graft, modified to express high levels of OAT as an ornithine-catabolizing skin-based enzyme sink, is investigated. Two OAT-containing retroviral vectors were constructed with or without a resistance gene. When packaged in a retroviral vector particle generated with the gibbon ape leukemia (GALV) virus envelope (PG13), these vectors could readily transduce >50% of target keratinocytes. The transduced keratinocytes in culture expressed up to 75-fold more OAT than normal control keratinocytes and these gene-modified cells extracted [14C]ornithine more efficiently than controls. The vector prepared without neo transduced cells more efficiently and led to higher levels of OAT expression than the neo-containing vector. Ornithine catabolism was maintained at high levels when the transduced patient keratinocytes were differentiated in vitro as a multilayered cutaneous organoid.

Renal tubular function in cyclosporine-treated patients.

Renal tubular function was studied in 32 consecutive patients treated with cyclosporine for autoimmune uveitis. Cyclosporine dosage was modified to maintain the serum creatinine level at less than 2 mg/dl. No evidence of aminoaciduria, glucosuria, hypokalemia, hypophosphatemia, or hypouricemia indicative of the Fanconi syndrome was detected during three to six months of observation. The renal tubular reabsorption of phosphate, determined by renal threshold phosphate concentration (TmPO4/GFR), remained unchanged. An early decrease in the serum magnesium level was accompanied by a decrease in daily urinary magnesium excretion. Concurrent with the development of a mild reduction of the glomerular filtration rate, the fractional excretion of magnesium was slightly higher and that of calcium was lower than pretreatment values. There were modest elevations of serum uric acid and potassium values. Furthermore, lysozymuria was not observed. Thus, the alterations in tubular functions observed in our cyclosporine-treated patients are comparable to those associated with mild chronic renal insufficiency of various causes and are not specific manifestations of cyclosporine tubular toxicity.

Side effects of systemic cyclosporine in patients not undergoing transplantation.

Twenty-six patients with ocular inflammatory disorders of presumed autoimmune origin were treated with oral cyclosporine. Cyclosporine is a potent T cell regulatory agent that has been utilized extensively in organ transplantation. In general, the patients in this study did not have chronic debilitating illnesses that are observed in organ transplant recipients, did not receive corticosteroids in addition to cyclosporine, and did not undergo any surgical procedure during their treatment. This study describes the observed adverse reactions in this group of patients not undergoing transplantation. The reported side effects of cyclosporine in organ transplant recipients have included nephrotoxicity, hepatotoxicity, infections, lymphoma, hirsutism, gingivitis, and central nervous system toxicity. Side effects were observed that were similar to those in previous reports, but the severity of the nephrotoxicity and hepatotoxicity appeared to be less. Nephrotoxicity occurred in eight patients and hepatotoxicity occurred in one patient. No lymphomas were seen. Hypertension and anemia each were observed in six patients. In addition, previously unreported effects of hyperuricemia, elevated sedimentation rate, and hidradenitis were observed. However, the overall severity of the side effects did not seriously affect the usage of cyclosporine in the patients in this study. Cyclosporine may be useful in the treatment of other autoimmune diseases.

Increased survival of a cohort of patients with acquired immunodeficiency syndrome and cytomegalovirus retinitis who received sodium phosphonoformate (foscarnet).

PURPOSE: To evaluate the impact of foscarnet on the longevity of persons with human immunodeficiency virus, type 1 (HIV-1) infection and cytomegalovirus (CMV) retinitis. PATIENTS AND METHODS: A cohort of 24 patients with acquired immunodeficiency syndrome (AIDS) and CMV retinitis received sodium phosphonoformate (foscarnet) as part of a controlled efficacy trial at the National Institutes of Health. Foscarnet was continued for as long as it was tolerated. Antiretroviral therapy was given to the patients as tolerated. Long-term follow-up was available on all patients. RESULTS: Seventeen patients received zidovudine during or after receiving foscarnet, 2 patients received dideoxyinosine, 2 patients zidovudine and dideoxyinosine, and 3 patients received no specific antiretroviral agent. Patients received foscarnet for a mean of 6.2 months (median, 4 months; range, 10 days to 22 months). Ten patients required a change to ganciclovir therapy at some time after receiving foscarnet. The median time from the diagnosis of CMV retinitis until death was 13.5 months (range, 3 to 34 months). Patients lived longer than untreated or ganciclovir-treated historical controls with AIDS and CMV retinitis. There was no difference in the survival of patients treated with foscarnet at the time of diagnosis and those patients treated with foscarnet only after progression of their CMV retinitis. CONCLUSIONS: These data suggest that foscarnet may prolong the survival of persons with AIDS and CMV retinitis and should be the initial treatment of choice in these patients.

Treatment of corneal allograft rejection with the cytotoxin IL-2-PE40.

IL-2-PE40 is a recombinant chimeric protein composed of IL-2, fused to a modified pseudomonas exotoxin. This molecule is extremely toxic to activated T cells expressing high-affinity IL-2R. We used this new molecule for selective immunosuppression to treat corneal allograft rejection in the rat, using Fisher and Lewis rats, a strain combination differing only in medial and minor histocompatibility antigens. The effect of IL-2-PE40 on the immunologic response was studied using both a heterotopic corneal graft model and orthotopic grafts. At the dose of 0.31 micrograms/g given intraperitoneally every 12 hr, IL-2-PE40 produced a significant reduction of both total lymph node cells and cytotoxic-T-cell (CTL) activity in draining lymph nodes (DLN) of heterotopically grafted animals. IL-2-PE40 treatment also significantly reduced the clinical rejection score and cumulative rejection rate (CRR) in orthotopic grafts and appears to be a very effective immunosuppressive agent.

Heterologous epitopes of IRBP protect against autoimmune uveitis induced by the autologous epitope.

Peptide 161-180 of human interphotoreceptor retinoid-binding protein (IRBP) contains a major uveitogenic epitope for mice of the H-2r haplotype. The human and bovine homologs differ from the autologous murine homolog by three and four amino acid residues, respectively. We compare the immunogenicity and pathogenicity of the three homologs, and investigate their ability to induce oral tolerance to experimental autoimmune uveoretinitis (EAU) induced by the autologous peptide. All three 161-180 homologs were pathogenic, with a hierarchy: human > murine > bovine. All crossreacted with each other and with IRBP. Feeding any of the three homologs (6 x 200 microg over 2 weeks) lowered antigen-specific responses and protected from EAU induced by the autologous homolog, and reduced EAU induced with whole IRBP. Peptide-fed mice had a reduced frequency of peptide-reactive T cells, suggesting a mechanism involving anergy and/or deletion. The results indicate that non-identical, but crossreactive, heterologous epitopes can protect against EAU induced by the corresponding autologous epitope, and even by the whole multi-epitope protein. These findings may impact on clinical trials in which uveitis patients are undergoing oral immunotherapy with bovine retinal antigens.

Effects of cyclosporine on T-cell subsets in experimental autoimmune uveitis.

The effective inhibition of S-antigen (S-Ag) induced experimental autoimmune uveitis (EAU) by Cyclosporine (CsA) suggests strongly the important role of T-cells in the modulation of this disease. The authors evaluated the changes in T-cell subsets induced by this agent in S-Ag immunized Lewis rats. Using the fluorescence-activated cell sorter and monoclonal antibody preparations directed against rat T-cell subsets, a comparison was made between lymphocyte populations obtained from CsA or olive oil treated S-Ag immunized rats taken 5, 10, 12, and 14 days after antigenic challenge. The T-cell subpopulations of lymphocyte preparations from the spleen and peripheral blood of CsA-treated and control animals appeared to parallel each other, with both groups showing an increase in the suppressor/cytotoxic fraction beginning on day 12 and approaching the percentage of inducer cells by day 14. Lymphocyte preparations from lymph nodes draining the site of S-Ag immunization from CsA-treated animals demonstrated a different T-cell subset profile than did controls. Beginning on day 10, the control group was noted to have an increased inducer cell fraction as compared with the CsA group. This increase in the inducer fraction paralleled an increase in the in vitro proliferative responses to the S-Ag. These data suggest that CsA appears to prevent the development of inducer cells in the lymph nodes draining the S-Ag immunization site, the T-cell subgroup the authors have seen capable of inducing EAU.

Human S-antigen determinant recognition in uveitis.

PURPOSE: Soluble antigen (S-Ag) is a member of the arrestin family of protein with which it shares a high level of homology. It is an immunologically privileged retinal antigen that can elicit experimental autoimmune uveitis (EAU) and is thought to be a target for ocular inflammatory diseases. This study was conducted to identify in humans, the immunogenic determinants of human S-Ag and to establish whether a specific response profile occurs in particular ocular inflammatory conditions. METHODS: Peripheral blood lymphocyte responses were measured against a panel of 40 overlapping synthetic peptides of human S-Ag in patients with chronic uveitis and compared with control subjects. Patients with Behçet disease, sarcoidosis, Vogt-Koyanagi-Harada, and sympathetic ophthalmia were tested. RESULTS: A limited number of immunodominant determinants were identified for Behçet disease and sarcoidosis. These were all located at sites of limited homology with other known arrestins. In addition, several individual patients had prominent proliferative responses to multiple determinants well above that of control subjects. This determinant spread was observed in all disease entities except sympathetic ophthalmia, which did not show any immunoreactivity to S-Ag. Significant response shifts were also noted over time in two patients. CONCLUSIONS: The results indicate that there are specific immunodominant determinants to human S-Ag in patients with certain forms of uveitis. However, in individual patients, response is not limited to these determinants. In the chronic stage of disease, response is spread over many determinants.

Effects of cyclosporine and other immunosuppressive drugs on experimental autoimmune uveoretinitis in rats.

Five immunosuppressive and anti-inflammatory agents were tested for their effects on development of experimental autoimmune uveoretinitis (EAU) and immune responses to S-antigen in rats immunized with this retinal antigen. When administered daily from day 0-14 after immunization, cyclosporine at 5-20 mg/Kg was nontoxic and yet effective in inhibiting the development of EAU for at least 30 days. All other tested drugs were found toxic at their immunosuppressive doses. Of these drugs, only cyclophosphamide (at 5-20 mg/Kg) was capable of inhibiting EAU in some of the treated rats for up to 30 days. Other agents, bredinin (40-100 mg/Kg), dexamethasone (0.2-0.4 mg/Kg), or colchicine (0.5 mg/Kg) produced only a delay in the disease onset. Cyclosporine was also unique in its effect on the immune responses of the rats by selectively inhibiting only the specific T-cell-mediated responses to S-antigen (delayed skin response and lymphocyte response in culture), while having no negative effect on antibody production or the lymphocyte response to the polyclonal mitogen, concanavalin A. Other drugs, when effective, inhibited all types of immune response. In addition, cyclosporine was capable of preventing EAU even when given to rats as late as from day 7 after immunization. Only cyclophosphamide (at 20 mg/Kg/day) had a similar effect on 1/3 of the rats, while other drugs only delayed or had no effect on the disease onset when given by this late schedule.

Adoptive transfer of experimental autoimmune uveoretinitis in rats. Immunopathogenic mechanisms and histologic features.

In order to learn about the immunopathogenic mechanisms of experimental autoimmune uveoretinitis (EAU), the capacity of lymphocytes to transfer the disease was studied. EAU was transferred to naive syngeneic rats by intraperitoneal injection of spleen or lymph node (LN) cells from S-antigen immunized rats, following their incubation in culture with either S-antigen or concanavalin A (Con A). In contrast, the same cells did not cause inflammatory changes in the recipient eyes when injected intravitreally. The identity of the lymphocytes that transfer EAU was determined by using monoclonal antibody enriched subsets of lymphocytes. EAU was transferred by the subset of helper/inducer T-cells, but not by T-cells of the suppressor/cytotoxic subset. Recipient rats of spleen or LN cells cultured with S-antigen exhibited both humoral and cellular immune responses to S-antigen. On the other hand, recipients of spleen cells cultured with Con A developed only cellular immune response to S-antigen. Yet, both groups of recipients fully developed EAU. The clinical and histologic changes in recipient rats closely resembled those in rats in which EAU was induced by active immunization. Severe tissue damage occurred at the photoreceptor cell layer, but inflammatory infiltration also was found in other ocular tissues. Involvement of polymorphonuclear leukocytes (PMNs) was noted throughout ocular tissues even in the eyes of recipients with no detectable antibodies to S-antigen, suggesting that the ocular PMNs infiltration in rats is not necessarily the result of an Arthus-like inflammatory process.

Involvement of the pineal gland in rats with experimental autoimmune uveitis.

Pineal glands of rats with experimentally induced autoimmune uveitis (EAU) were studied histologically. Inflammatory changes, characterized by mononuclear infiltration, were found in the pineal glands of one-third of the Lewis rats that developed EAU by active immunization with S-antigen. No changes in the pineal gland were observed in AVN rats which are "low responders" for EAU and did not develop ocular disease. Frequency and severity of both pineal gland and ocular involvement clearly were elevated by intravenous injection of Bordetella pertussis along with the S-antigen immunization; all B. pertussis-treated rats of both Lewis and AVN strains developed pineal and ocular changes. Inflammatory changes of the pineal gland also were found in rats in which EAU was induced passively by transfer of lymphocytes from S-antigen-immunized donors. The frequency of involvement of the pineal gland was found to be lower than that of the retinas in rats where EAU was induced by active immunization or by adoptive transfer of lymphocytes.

Cyclosporine-induced alterations of humoral response in experimental autoimmune uveitis.

Cyclosporine (CsA) has been shown to be effective in preventing S-antigen (S-Ag) induced experimental autoimmune uveitis (EAU) in Lewis rats. Alterations in the humoral immune responses associated with CsA therapy are illustrated by lower peak and delayed production of circulating anti-S-Ag antibodies in a proportional relationship to the dose of CsA in EAU. Circulating immune complexes were not detected in rats with EAU or in rats treated with CsA and without disease. These findings further support the important role of T-cells in EAU and further demonstrate the effect of CsA on helper T-cells. The kinetics of antibody production by S-Ag-immunized rats appears altered by CsA.

The role of mast cells in endotoxin-induced uveitis.

PURPOSE: To investigate the role of mast cells in the induction of endotoxin-induced uveitis (EIU). METHODS: We previously showed that the mean mast cell number in the anterior uvea was greatest for Lewis rats, lowest for Brown Norway (BN) rats, and intermediate for LBNF1 rats. In the current experiment, we assessed the time of onset and severity of EIU in these three rat strains. We then studied changes in mast cell numbers in the anterior uvea during the induction period of EIU. RESULTS: Time of onset and severity of EIU were related to the number of mast cells in the anterior uvea. EIU occurred earliest in the Lewis rats, and the maximum mean grade of ocular inflammation on a scale of 0 (no inflammation) to 4 (severe inflammation) +/- standard error of the mean was 3.87 +/- 0.13 for Lewis rats, 1.06 +/- 0.06 for BN rats, and 1.19 +/- 0.12 for LBNF1 rats. The difference between the mean grade of inflammation in the Lewis rats and the other two strains was highly statistically significant (P < .001). In the Lewis rats, mast cell numbers +/- SEM decreased from 68.9 +/- 10.8 at baseline to 49.6 +/- 5.9 4 hr after lipopolysaccharide (LPS) injection and to 27.6 +/- 8.4 8 hr after LPS injection, suggesting that mast cell degranulation occurs before the development of EIU. CONCLUSION: Mast cells in the anterior uvea appear to potentiate endotoxin-induced ocular inflammation.