Identification of novel dendritic cell populations in normal mouse retina

PURPOSE

Whether tissue resident or infiltrating antigen-presenting cells (APCs) are involved in modulating immune responses in the retina and initiating inflammation is controversial. In this histologic study, the authors examine the retinas of mice strains with different susceptibility to experimental autoimmune uveoretinitis (EAU) for tissue resident APC.

METHODS

Retinal wholemounts from normal and inflamed eyes of B10R III, C57BL/6, BALB/c, and ABH Biozii mice were immunostained for APC markers (33D1, CD11c, CD11b, major histocompatibility complex [MHC] class II, F4/80, CD80, CD86, CD205, mPDCA, B220, and GR1) and analyzed by confocal fluorescence microscopy using emission fingerprinting and three-dimensional reconstruction techniques. Hematoxylin and eosin-stained histologic sections were used to evaluate EAU disease scores and to assess outer blood retina barrier (retinal pigment epithelium [RPE]) structures.

RESULTS

A population of 33D1(+) cells was identified exclusively in the peripheral margins and juxtapapillary areas of the retina in normal, nonimmunized C57BL/6 adult mice. These cells were also MHC class II(high), and their location corresponded to sites of earliest inflammation in EAU. Numbers in the papillary area were very low (less than 10), but this region marked the predominant anatomic site for initiation of inflammation in this moderately susceptible strain. The distribution and phenotype of these cells within the retinas differed between mouse strains exhibiting different disease susceptibility. In EAU-resistant BALB/c mice, many more 33D1(+) dendritic cells were present in the normal retina but were MHC class II(low/-). Conversely, no 33D1(+) or MHC class II (+) dendriform cells could be found in the normal retinas of highly EAU-susceptible B10.RIII mice.

CONCLUSIONS

A novel population of 33D1(+) DCs was identified in normal mouse retina. The function of these cells remains to be defined, but increased numbers correlate positively with structural abnormalities in the RPE and increased resistance of the strain to EAU.

Contribution of TNF-alpha to leukocyte adhesion, vascular leakage, and apoptotic cell death in endotoxin-induced uveitis in vivo

PURPOSE

To investigate the effect of TNF-alpha on leukocyte adhesion, vascular leakage, and apoptotic cell death in endotoxin-induced uveitis (EIU) in the rat.

METHODS

EIU was induced in Long-Evans rats by a single footpad injection of lipopolysaccharide (LPS; 350 microg/kg) from Salmonella typhimurium. A single injection of recombinant TNF receptor P75 (etanercept) was given subcutaneously 24 hours before the administration of LPS. Twenty-four hours after administration of LPS, leukocyte adhesion was evaluated in vivo with SLO-acridine orange angiography and ex vivo with concanavalin A lectin staining of retinal flatmounts. Neutrophil activation was quantified by a myeloperoxidase activity assay. Vascular leakage was assessed by Evans blue extravasation. Retinal cell death was assessed with TUNEL staining and quantified with a modified ELISA protocol. Involvement of caspase-3 and -8 was determined by M30 antibody staining, Western blot analysis, and a test for enzymatic activity.

RESULTS

Twenty-four hours after the LPS injection, significant increases in leukocyte rolling, adhesion, and activation were observed. In addition, increased levels of apoptosis in the vascular endothelium and the ganglion cell and inner nuclear layers and activation of caspase-8 and -3 were observed. After administration of the TNF-alpha inhibitor, significant reduction in the leukocyte rolling, adhesion, activation, and apoptosis in all the affected layers was observed. The quantitative analysis of vascular leakage revealed a significant decrease after treatment with etanercept. Retinal cell death quantification showed a significant decrease after treatment with the TNF-alpha inhibitor.

CONCLUSIONS

Anti-TNF-alpha treatment reduces the LPS-induced increases in leukocyte rolling, adhesion, and vascular leakage in this rat model of inflammatory uveitis. These results suggest the involvement of TNF-alpha in inflammatory uveitis and its potential use as a therapeutic agent in the reduction of ocular inflammation.

Immunological effects of allopurinol in the treatment of experimental autoimmune uveitis (EAU) after onset of the disease

PURPOSE

Allopurinol reduces oxidative tissue damage and exerts immunomodulating effects in the treatment of experimental autoimmune uveitis (EAU). However, the mechanism of the immunologic pathway remains unclear. In previous studies, treatment was started at the time of immunization. Therefore, whether allopurinol prevents the onset of the disease (i.e., acts in a protective manner) is not known.

METHODS

Sixteen male Lewis rats were used: 6 EAU without therapy [control]; 4 EAU with allopurinol treatment starting 7 days after immunization [AL7]; and 6 EAU with allopurinol treatment starting 11 days after immunization [AL11]. Their sera were tested against Western blots of sodium dodecyl sulfate-polyacrylamide gel electrophoresis of retinal proteins. Based on digital image analysis, analysis of discriminance was done.

RESULTS

There were significant immunomodulating effects in both therapy groups (Wilks' lambda 0.001, P < 0.008) compared to controls. However, the effects were more pronounced in the AL7 group, where peak intensities and the number of peaks were markedly more reduced.

CONCLUSIONS

Immunomodulating effects of allopurinol can be detected even if the therapy starts after the onset of the disease. Thus allopurinol strongly influences the immunologic mechanism in this model of autoimmune disease. In view of its minimal side effects, the drug could be a promising alternative for the therapy and prophylaxis of uveitis and other autoimmune diseases.

Chemokine and chemokine receptor expression during experimental autoimmune uveoretinitis in mice

BACKGROUND

Chemokines act as chemoattractants and activators of specific leukocytes at the site of inflammation. In this study, we investigated serial expression of chemokines and chemokine receptors in the eye with experimental autoimmune uveoretinitis (EAU) using RNAse protection assay, and confirmed their expression by immunohistochemical staining.

METHODS

B10.A mice were immunized with 50 micro g of interphotoreceptor retinoid binding protein (IRBP) emulsified in complete Freund's adjuvant in order to induce EAU. The eyes were enucleated 0, 7, 14 and 21 days after IRBP immunization to analyze mRNA expression of chemokines and chemokine receptors in the posterior segment. In addition, expression of IP-10 and CXCR3 was analyzed by immunohistochemistry.

RESULTS

The gene expression of RANTES, IP-10, and MCP-1 was upregulated on day 14 after immunization (early stage of EAU). The expression of chemokine receptors (CCR2 and CCR5) associated with Th1-type T cells correlated with their appropriate ligands. Furthermore, immunohistochemical study showed that IP-10 and CXCR3, the receptor for IP-10, were strongly expressed in the posterior segment of the eyes from mice with EAU.

CONCLUSION

These results suggest that RANTES, IP-10 and MCP-1 may contribute to the recruitment of Th1-type T cells into the eye during the development of EAU in mice.

Posterior uveitis: an under-recognized adverse effect of pamidronate: 2 case reports

Ocular adverse effects of pamidronic acid are rare but well documented. Pamidronate, an inhibitor of bone resorption used primarily in the management of tumor-induced hypercalcemia and Paget's disease, is reported to cause conjunctivitis, anterior uveitis, and infrequently episcleritis and scleritis. It is hypothesized that an allergic or immunologic phenomenon caused by drug-indued immune complex formation is at fault. The reason why the uvea is a target organ is unclear. The acute inflammatory response seems unrelated to the dose of the drug, the way of administration, or the activity of Paget's disease or malignancy. We report two cases of pamidronate-induced posterior uveitis, following the WHO Causality Assessment Guide of Suspected Adverse Reactions. Uveitis and scleritis have been reported in association with a variety of topical, intraocular, periocular, and systemic medications. Seven criteria were proposed to establish causality of adverse events by drugs. Only systemically administered biphosphonates meet all seven criteria. Where pamidronate is currently considered as the drug of choice in diverse strategies, the adverse ocular effects should be well known to physicians in order to make rapid diagnosis and stop the drug causing adverse reaction.

Antiuveitis and inhibition of fibroblast-like corneal and conjunctival cell cultures by interleukin-1 blockers, CK 125, CK 126 and CK 128

Three new interleukin-1 (IL-1) blockers, CK 125, CK 126 and CK 128, were studied for their effects on IL-1-induced uveitis in rat eyes. They were more potent (at 3-10 mg/kg t.i.d.) than prednisolone (20 mg/kg t.i.d.) in effectively inhibiting posterior uveitis. They were also found to inhibit fibroblast-like corneal cells at 10-300 micrograms/ml concentrations and conjunctival cells at 1-30 micrograms/ml levels. The incorporation of leucine into corneal and conjunctival cells was either stimulated or unaffected by CK 126, indicating that the inhibition of cell growth has nothing to do with the protein synthesis. However, the incorporation of uridine into corneal and conjunctival cells was markedly inhibited by CK 126 at 3-30 micrograms/ml concentrations whereas the incorporation of thymidine into the cells was inhibited at a lesser extent than that of uridine. These results indicate that cell inhibition by CK 126 could be related mainly to the synthesis of mRNA and, to a lesser extent, to DNA synthesis.

Systemic toxicity of topical and periocular corticosteroid therapy in an 11-year-old male with posterior uveitis

PURPOSE

To report a case of systemic corticosteroid toxicity resulting from topical and periocular therapy.

METHODS

Treatment and follow-up of an 11-year-old male with uveitis are illustrated. Initial presentation of the patient was bilateral iridocyclitis, for which he was treated with prednisolone acetate 1% every 2 hours for 6 months. Subsequently, posterior uveitis developed, necessitating posterior subtenon injections.

RESULTS

After initial topical corticosteroid therapy, the patient developed a cushingoid habitus accompanied by increased lanugo hair, acanthosis nigricans, posterior subcapsular lens opacities, and increased intraocular pressure. Cushingoid stigmata worsened after administration of posterior subtenon injection of corticosteroids. The patient's truncal obesity worsened, and his linear growth stopped.

CONCLUSIONS

Systemic toxic effects may develop as a result of topical and local use of ophthalmic corticosteroid preparations in susceptible patients.

Immune recovery uveitis in patients with AIDS and cytomegalovirus retinitis after highly active antiretroviral therapy

PURPOSE

To estimate the incidence and describe the characteristics of immune recovery uveitis in patients with acquired immunodeficiency syndrome (AIDS) and cytomegalovirus retinitis treated with highly active antiretroviral therapy.

METHODS

The records of all patients with AIDS and cytomegalovirus retinitis from 1995 to 1998 seen at the AIDS Ophthalmology Service of the Johns Hopkins Medical Institutions were reviewed. Eighty-two patients with cytomegalovirus retinitis treated with highly active antiretroviral therapy were identified. Thirty-three patients (40.2%) were classified as responders to highly active antiretroviral therapy, defined as an increase in CD4+ T-cell count by 50 cells/microL or more to a level of 100 cells/microL or more.

RESULTS

Immune recovery uveitis occurred in six patients. Among the 33 patients with an immunologic response to highly active antiretroviral therapy, the incidence rate of immune recovery uveitis was 0.109/person-year. Ocular complications associated with immune recovery uveitis included cystoid macular edema (four patients), epiretinal membranes (two patients), and optic disk neovascularization (one patient).

CONCLUSIONS

Immune recovery uveitis was uncommon in our population but may have vision-impairing complications.

Macrophages and dendritic cells in IRBP-induced experimental autoimmune uveoretinitis in B10RIII mice

PURPOSE

To investigate the characteristics of the mononuclear cell infiltrate in murine experimental autoimmune uveoretinitis (EAU).

METHODS

EAU was induced by immunization with bovine interphotoreceptor retinal binding protein (IRBP) in Freund's complete adjuvant (subcutaneous injection) and pertussis toxin (intraperitoneal injection) in B10RIII mouse. Then animals were killed on days 7, 9, 12, 15, 20, 26, and 39 after immunization. Eyes were processed for hematoxylin and eosin staining to characterize the disease and to assess the severity and extent of the EAU. Single and dual immunohistochemical staining in various combinations with monoclonal antibodies against CD45, CD4, CD8, major histocompatibility complex (MHC) class II, CD11c, NLDC-145, and a variety of macrophage markers was performed.

RESULTS

The authors' results showed that vitritis, vasculitis and perivasculitis, retinal detachment, and granuloma formation in retina and choroid were the predominant features of IRBP-induced B10RIII mice EAU. Immunohistologic results showed that CD4+ T cells and macrophages were the main infiltrating cells in retina and choroid throughout the entire course of the disease. MHC class II negative macrophages expressing antigens reacting with MOMA-2, F4/80, sialoadhesin, and CD11b were prominent during the peak phase of tissue damage in the retina and choroid. Dendritic cells (DCs) characterized by dual positivity for MHC class II and CD11c and negative for sialoadhesin appeared at time of disease onset and continued to be recruited during the inflammatory process. DCs at the site of inflammation were NLDC-145 weak and CD8 negative, indicating that they were of the myeloid rather than the lymphoid lineage.

CONCLUSIONS

The results suggest that EAU in B10RIII mice is initiated by local-infiltrating, dendritic antigen-presenting cells, whereas tissue damage is associated with sialoadhesin-positive, phagocytic nonantigen-presenting macrophages during the effector stage.

The role of costimulatory molecules B7-1 and B7-2 in mice with experimental autoimmune uveoretinitis

BACKGROUND

Onset of experimental autoimmune uveoretinitis (EAU) is believed to involve a CD4-positive type 1 T helper cell (Th1) immune response, with inhibition involving a Th2 immune response. Development of Th1 and Th2 responses involves the participation of the costimulatory molecules B7-1 and B7-2, respectively. The purpose of this study was to investigate the role of B7-1 and B7-2 in the EAU model in mice.

METHODS

B10.A mice were immunized with interphotoreceptor retinoid-binding protein (IRBP) and given daily intraperitoneal injections of either phosphate-buffered saline (control), mouse monoclonal antibody (mAb) to B7-1, mAb to B7-2, or mAb to both B7-1 and B7-2. Eyes were evaluated by histopathological criteria and cytokines were assayed in culture medium of IRBP-stimulated lymphocytes. Cellular immune responses were measured by cell proliferation assay under IRBP stimulation.

RESULTS

Rates of EAU onset were 5/10 (50%) for control mice, 1/9 (11%) for mice treated with anti-B7-1 mAb, 5/6 (83%) for mice treated with anti-B7-2 mAb, and 2/6 (33%) for mice treated with both anti-B7-1 and anti-B7-2 mAb. Mean histopathological severity scores were 2. 4+/-0.8, 1.0+/-0, 2.6+/-1.0, and 1.0+/-0, respectively. Production of IL-5 was significantly increased in mice treated with anti-B7-1 mAb, while IFN-gamma was increased in mice treated with anti-B7-2 mAb. Spleen cell proliferation was significantly reduced in mice treated with anti-B7-1 mAb.

CONCLUSIONS

These results suggest that the costimulatory molecules B7-1 and B7-2, via their influence on generating Th1 and Th2 immune responses, play an important role in the clinical outcome of EAU in mice immunized with IRBP.

Anti-inflammation and antifibroblastic actions of interleukin-1 blockers

Interleukin-1 (IL-1) blockers, CK 127 and CK 129, were found to inhibit IL-1-induced posterior uveitis very effectively at 3-10 mg/kg i.p. and were more potent than prednisolone which required at least 20 mg/kg i.p. to achieve the same level of anti-uveitis action. CK 127 and CK 129 were also found to be effective in inhibiting fibroblast-like corneal cells at 30-300 micrograms/ml and conjunctival cells at 0.3-10 micrograms/ml. These results indicate that IL-1 blockers are more potent in inhibiting the cell growth of conjunctival cells than that of corneal cells. From in vitro cell culture experiments, it was found that inhibition of cell growth could be due primarily to the inhibition of DNA. Although the inhibition of cell growth was due mainly to the inhibition of DNA synthesis, mRNA synthesis was also markedly inhibited. In both cells, the protein synthesis was unaffected in a few cases and markedly stimulated in most cases.

T cell traffic and the inflammatory response in experimental autoimmune uveoretinitis

PURPOSE

To quantify S-antigen-specific (S-Ag) T cells in the retina after adoptive transfer, and to evaluate their role in the initiation and progress of destructive ocular inflammation in experimental autoimmune uveoretinitis (EAU).

METHODS

Lewis rats were administered 10 x 10(6) S-Ag-specific T cells from the SP35 cell line or 10 x 10(6) concanavalin A-stimulated syngeneic spleen cell lymphoblasts labeled with lipophilic PKH26 fluorescent dye immediately before intravenous inoculation. Labeled cells in each retina were counted at various times from 4 to 120 hours after cell transfer by fluorescence microscopic analysis of each dissociated retina. Recipient eyes were examined within the same period by light and confocal microscope.

RESULTS

SP35 T cells showed a biphasic distribution in the retina. The first peak of 160 cells/retina was noted at 24 hours. A steady decline of labeled cells at 48 and 72 hours was followed by a rapid increase at 96 and 120 hours. Concanavalin A-stimulated, control-labeled cell populations showed an identical peak at 24 hours but a persistent decline thereafter; only two or three T cells were present in each retina at 120 hours. Concurrent inoculation of SP35 cells and nonspecific T cell blasts did not produce more SP35 cells than control cells in the retina at any time. Microscopic analysis showed mononuclear cell infiltration of the iris, ciliary body, and aqueous humor at 48 hours, which intensified rapidly and persisted through 120 hours. Retinal inflammation did not begin until 80 hours. Mononuclear cell adherence to vascular endothelium and perivascular macrophage infiltration of the innermost layers progressed to edema, and profound destructive inflammation and loss of retinal stratification were observed at 120 hours.

CONCLUSIONS

There is no evidence of a blood-ocular or blood-retinal barrier to activated T cell blasts. Autologous S-Ag does not provoke a more rapid entry of specific T cells at that site. The data confirm that anterior segment inflammation precedes retinal inflammation, even though S-Ag-specific T cells were present in the retina within a few hours after cell transfer. Because S-Ag is clearly present in the retina, delay in antigen presentation at that site may account for the temporal difference between retinal and anterior segment inflammation.

Transient vitreous inflammatory reactions associated with combination antiretroviral therapy in patients with AIDS and cytomegalovirus retinitis

PURPOSE

To report the observation that a transient vitreous inflammatory reaction may develop in the eyes of patients with acquired immunodeficiency syndrome (AIDS), cytomegalovirus retinitis, and an increased CD4+ T-lymphocyte count during treatment with antiretroviral therapy including a protease inhibitor.

METHODS

We reviewed the medical records of eight patients with AIDS and cytomegalovirus retinitis who developed vitreous inflammatory reactions greater than those usually seen with this disease.

RESULTS

Vitreous inflammatory reactions obscured the view of the posterior pole in all patients. No iris nodules, synechiae, glaucoma, or cystoid macular edema were observed. Six patients had unilateral cytomegalovirus retinitis, and, in each, the inflammation occurred only in the eye with cytomegalovirus retinitis. The vitreous inflammatory reactions were associated with clinically inactive cytomegalovirus retinitis in six patients, with disease reactivation in one patient, and were present at diagnosis of active disease in one patient. Cytomegalovirus retinitis has not recurred in any of these patients since their episodes of vitreous inflammation. Vitreous inflammation developed in all eight patients after a substantial increase in CD4+ T-lymphocyte counts caused by combination antiretroviral therapy. Five patients had CD4+ T-lymphocyte counts of greater than 100 cells per microl at the time the vitreous inflammatory reaction developed. No other causes of uveitis were found.

CONCLUSIONS

Patients with AIDS and cytomegalovirus retinitis may develop transient intraocular inflammation associated with combination antiretroviral therapy. We believe that this inflammation reflects an improved immune response against cytomegalovirus.

Resident and infiltrating cells in the rat iris during the early stages of experimental melanin protein-induced uveitis (EMIU)

Experimental melanin protein-induced uveitis (EMIU) is reported to be a model of anterior uveitis and choroiditis in which the retina is spared. In this study, we chose to compare EMIU with experimental autoimmune uveoretinitis (EAU), a well-recognised model of endogenous posterior uveitis, with regard to the nature and dynamics of the cellular infiltrate in the iris. Female Lewis albino rats were immunised with mixtures of crude retinal extract/complete Freund's adjuvant (CFA) (EAU), phosphate-buffered saline/CFA (controls), or iris melanin/CFA (EMIU) using established protocols. Animals were sacrificed on days 10 and 13 (around disease onset). Following whole body perfusion fixation, irides were dissected from the remainder of the globe. Iris wholemount preparations were then subjected to immunohistochemical analysis in order to investigate both the dynamics of infiltrating leukocytes and the effects of the inflammatory changes on resident immune cells in the iris. The nature of the cellular infiltrate in both EMIU and EAU models was essentially similar, namely there was a rich infiltrate of EDI+ mononuclear cells, Ox42+ neutrophils and T cells. Resident tissue macrophages (ED2+) were slightly below normal densities in the iris of EAU animals and marginally elevated in EMIU animals, MHC class II (Ia) staining, associated in the normal eye with dendritic cells (DC), was considerably elevated in EMIU. It is likely that this was due to both increased DC numbers and an influx of Ia+ exudate macrophages. No striking difference was found in the nature and phenotype of the cellular infiltrate in the iris at the onset of the disease in these two models of uveitis (EAU and EMIU). This suggests that the anterior segment inflammation in both models represents non-specific changes secondary to cytokine release associated with interaction of activated antigen-specific T cells and target antigens, namely retinal photoreceptors in EAU and uveal tract melanin-containing cells in EMIU. Alternatively, it may suggest that antigen-presenting cells resident in the iris and ciliary body in normal eyes have access to ocular antigens on both sides of the blood-ocular barrier and are capable of activating circulating antigen-specific T cells in these models.

Tacrolimus-rapamycin combination therapy for experimental autoimmune uveoretinitis

Tacrolimus and rapamycin both belong to a new family of immunosuppressants, immunophilin ligands, but the mechanisms by which they inhibit T cell activation are different. Therefore, we tested the immunosuppressive effects of combination therapy with low doses of tacrolimus and rapamycin on experimental autoimmune uveoretinitis (EAU) in rats. Male Lewis rats, immunized with S-antigen (S-Ag) were given intraperitoneal injection of the combined drugs for 14 days after the immunization with S-Ag. Effects were evaluated by clinical observations, histological examination and immune response. The combination therapy with tacrolimus (0.1 mg/kg per day) and rapamycin (0.03 mg/kg per day) achieved 100% suppression of clinical EAU and 66.7% suppression of histological EAU; tacrolimus combined with a higher dose of rapamycin (0.1 mg/kg per day) caused 100% suppression clinically and histologically. Therapy with either drug alone achieved only partial suppression: tacrolimus alone (0.1 or 0.2 mg/kg per day) or rapamycin alone (0.03-0.2 mg/kg per day). Doubling the dose of either drug produced only 16.7% suppression with rapamycin or 50% suppression with tacrolimus. The serum antibody levels to S-Ag and proliferative response of lymphocytes to S-Ag were also significantly suppressed by the combination therapy with low doses of tacrolimus and rapamycin.

In vivo quantification of leukocyte behavior in the retina during endotoxin-induced uveitis

PURPOSE

The interaction between leukocytes and vascular endothelial cells plays an important role in various inflammatory disorders. This study evaluated leukocyte behavior in the retina during endotoxin-induced uveitis (EIU) in vivo.

METHODS

EIU was induced in female Lewis rats by footpad injection of lipopolysaccharide (LPS). The time-course changes of retinal leukocyte behavior were followed at 1.5, 3, 4.5, 6, 12, 24, 48, 72, and 120 hours after LPS treatment using acridine orange digital fluorography, consisting of high-resolution images from a scanning laser ophthalmoscope and a fluorescent nuclear dye of acridine orange.

RESULTS

Major retinal vessels were significantly dilated (P < 0.05) at 4.5 hours after LPS injection. The vasodilation, marked in veins, became maximum at 24 hours and subsided at 72 hours. Leukocytes were observed rolling along the walls of major veins at 4.5 hours. The number of rolling leukocytes gradually increased and reached a peak level of 33.8 +/- 3.4 cells/minute per major vein at 12 hours. Leukocyte rolling was still observed at 72 hours. No rolling of leukocytes was observed along the arterial walls throughout any experiments. The velocities of rolling leukocytes were determined at 6, 12, 24, and 48 hours. The leukocyte rolling velocity at 6 hours was significantly slower (33.3 +/- 2.8 microns/second, P < 0.05) than at the other three times (average, 46.6 microns/second). Cellular infiltration into the vitreous cavity was detected at 24 hours and reached its maximum at 48 hours.

CONCLUSIONS

This study demonstrates that it is possible to evaluate EIU by investigating retinal leukocyte behavior and that vasodilation of major retinal vessels and leukocyte-endothelial interactions precede inflammatory cell emigration into the vitreous. This method may be useful to quantify the severity of inflammation in EIU.

Inflammatory opacities of the vitreous in rifabutin-associated uveitis

PURPOSE

To describe rifabutin-associated uveitis with opacities in the inferior and posterior vitreous in three patients with acquired immunodeficiency syndrome.

METHOD

Case reports of the three patients are presented.

RESULTS

The patients, who were being treated with rifabutin and fluconazole, developed anterior and posterior uveitis. The posterior uveitis was characterized by white-yellow inflammatory opacities located in the inferior and posterior vitreous. Discontinuation of rifabutin and the start of topical corticosteroid therapy resulted in improvement of the uveitis and visual acuity.

CONCLUSION

Recognition of rifabutin-associated uveitis with opacities in the inferior and posterior vitreous may prevent unnecessary invasive diagnostic and therapeutic procedures.

Tetrandrine inhibits breakdown of blood-aqueous barrier induced by endotoxin and interleukin-1 alpha in rats

Tetrandrine was shown to significantly inhibit uveitis induced by endotoxin and interleukin-1 alpha (IL-1 alpha) in rats. The dose-response curve of IL-1 alpha-induced uveitis was inhibited in a non-competitive manner. The maximum inflammation induced by IL-1 alpha was suppressed to 58.4%, 38.3% and 18.3% of the control peak by 5 mg/kg, 10 mg/kg and 20 mg/kg t.i.d. of tetrandrine, respectively. The maximum inflammation induced by endotoxin was suppressed to 56.5% and 38.0% by 5 mg/kg and 10 mg/kg t.i.d. of tetrandrine, respectively. The mechanism of tetrandrine's anti-inflammation could involve numerous pathways of inflammation processes and multiple inflammatory mediators. The results of this study indicate that tetrandrine appears to be a broad spectrum, non-steroidal, novel ocular anti-inflammatory agent.

Suppression of experimental uveitis with monoclonal antibodies to ICAM-1 and LFA-1

PURPOSE

Intercellular adhesion molecule-1 (ICAM-1), which is one of the ligands for lymphocyte function associated antigen-1 (LFA-1), plays an important role in immune responses. To examine whether ICAM-1 and LFA-1 are involved in the pathogenesis of experimental autoimmune uveoretinitis (EAU), the authors investigated the therapeutic effect of anti-ICAM-1 monoclonal antibody (mAb) 1A29 and anti-LFA-1 alpha chain mAb WT.1 on retinal soluble antigen (S-Ag) and Freund's complete adjuvant (FCA)-induced EAU in rats.

METHODS

After immunization with S-Ag and FCA, rats were intraperitoneally injected with a monoclonal antibody, anti-ICAM-1 mAb 1A29 or anti-LFA-1 alpha chain mAb or control Ab, at 1.0 mg/kg body weight, according to the treatment schedule. Inflammation was examined clinically and histologically. Proliferative responses of splenocytes to S-Ag were also examined.

RESULTS

The development of EAU could be completely prevented by the administration of 1A29, 1.0 mg/kg, twice a week from day 0 to day 14, but was only partially suppressed by WT.1. However, semiweekly administration of 1A29 from day 0 to day 7, or from day 10 to day 17, did not suppress EAU.

CONCLUSIONS

These findings indicate that ICAM-1, LFA-1-dependent pathways are involved in the pathogenesis of EAU. In addition, these pathways seem to be required for both the induction and the development of this disease.

Concanavalin A-induced posterior subcapsular cataract: a new model of cataractogenesis

PURPOSE

To evaluate the effect of Concanavalin A (Con A) on cataract formation in New Zealand Albino rabbits. Uveitis is a chronic inflammatory condition of the eye involving the anterior and/or posterior segments. It may be acute or chronic and is associated with the development of posterior subscapular cataract over time. Con A is a nonspecific inflammatory agent and mitogen for T cells and some B cells. Used extensively in immunogenic studies Con A has been shown to induce uveitis after intravitreal injection in New Zealand Albino rabbits.

METHODS

In two separate studies, Con A was injected intracamerally or intravitreally into one eye of 12 New Zealand Albino rabbits and an equal volume of balanced salt solution was injected into the opposite eye as a control. In a third study, the effect of topical steroids after intravitreal injection of Con A was evaluated. In all studies, anterior and posterior inflammation and the development of cataract was monitored by slit lamp biomicroscopy and photography. Cataract formation was also studied histopathologically.

RESULTS

Initially, all eyes treated with Con A demonstrated moderate anterior chamber inflammation while eyes treated with balanced salt solution showed no inflammation. Three months after treatment, posterior subcapsular cataracts were present in all rabbit eyes treated with intravitreal Con A. In the third study, topical steroid treatment of Con A-induced inflammation significantly reduced anterior chamber inflammation but had no effect on vitreous humor and posterior subcapsular cataract formation.

CONCLUSION

This experimental model was the first to demonstrate the development of posterior subcapsular cataracts after Con-A induced inflammation. The cataract was clinically and histologically similar to human posterior subscapular cataracts.

Inhibition of crystallins-induced inflammation in rabbit eyes with five phytogenic compounds

Ocular inflammation was induced by injection of crystallins (lens protein) intracamerally and endotoxin intravitreously into rabbit and rat eyes, respectively, and was measured with fluorophotometry by quantitating the amount of fluorescein which entered into the globe. Five compounds isolated from anti-inflammatory Chinese herbs were studied for their effects on ocular inflammation. It was found that lens protein-induced inflammation was inhibited significantly by the topical instillation of pulegone (0.5%), friedelin (0.5%), and sabinene (1%), but not by dihydrojasmon or naringin at concentrations up to 1%. However, none of these compounds inhibited endotoxin-induced posterior uveitis.

Multiple, autoreactive TCR V beta genes utilized in response to a small pathogenic peptide of an autoantigen in EAU

The restricted usage of particular T cell receptor beta chain genes in autoimmune disease was studied in LEW rats using T cell hybridomas specific for an immunodominant sequence of bovine retinal S-Ag, which induces experimental autoimmune uveoretinitis. T cell hybridomas from a pathogenic T cell line, R858, specific for residues 273-289 of bovine retinal S-Ag were analyzed in order to determine the contribution of their TCR V beta to self specificity as determined by recognition of the pathogenic epitope represented in the autologous rat S-Ag sequence. Six different, functional TCR rearrangements were expressed by the panel of hybridomas, including two distinct V beta 8.2 rearrangements and functional V beta 10, V beta 14, V beta 19 rearrangements, and an unidentified V beta gene. All hybridomas were Ag specific and reacted both to nonself-peptide derivatives as well as to self-peptide homologues. No unique pattern of peptide reactivity distinguished V beta 8.2+ hybridomas from V beta 8.2- hybridomas; all of the hybridomas were most reactive to the nonself sequences and reacted to self peptide with one to three orders of magnitude less sensitivity. However, all V beta 8.2+ hybridomas were much better responders overall and were activated by lower concentrations of all peptides than were V beta 8.2- hybridomas. Although V beta 8.2 gene usage is strongly associated with autoimmune pathology, these data show that in LEW rats several different TCR V beta genes are utilized in response to a short pathogenic sequence of this autoantigen and show that V beta 8.2 receptors are not uniquely self-reactive. However, the enhanced reactivity to Ag of V beta 8.2+ hybridomas relative to V beta 8.2- hybridomas specific for the same peptide may help explain the close association of V beta 8.2 TCR gene usage with pathogenicity found in autoimmune disease models.

Synergistic uveitic effects of tumor necrosis factor-alpha and interleukin-1 beta

Tumor necrosis factor (TNF) and interleukin-1 (IL-1), cytokines with multiple, overlapping biologic activities, have been shown to interact synergistically in nonocular tissues. To test the hypothesis that coinjection of TNF and IL-1 interact synergistically in the eye, low, marginally inflammatory doses of human recombinant TNF-alpha (4000 U), IL-1 beta (40 U), and TNF-alpha+IL-1 beta (TNF-alpha/IL-1 beta) were injected into the vitreal chamber of the rabbit eye, and inflammation was assessed at 6, 24, 48, and 168 hr post-cytokine injection. TNF-alpha/IL-1 beta induced an anterior uveitis that was barely detectable at 6 hr, increased at 24 hr, peaked at 48 hr, and largely resolved by 168 hr. Synergy was observed for infiltration of inflammatory leukocytes into aqueous humor at 24 and 48 hr and for protein and prostaglandin E levels in aqueous humor at 48 hr. Based upon protein levels in vitreous humor, TNF-alpha/IL-1 beta also induced a posterior uveitis. This posterior uveitis was not apparent until 48 hr and then increased significantly at 168 hr. At 48 and 168 hr, the effects of TNF-alpha/IL-1 beta on protein levels in vitreous humor were consistent with a synergistic interaction. Results of separate experiments using higher dose combinations of TNF-alpha/IL-1 beta and a longer time course suggested that the effects of TNF-alpha/IL-1 beta on the blood vitreous barrier persisted beyond 168 hr. The results of this study support the hypothesis that TNF-alpha and IL-1 beta interact synergistically when injected into the rabbit eye.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of ocular inflammation by chalcone derivatives and prednisolone

Posterior uveitis was induced by injection of 10 micrograms endotoxin intravitreally into rat eyes and anterior ocular inflammation was induced by injection of 0.75 mg of lens protein intracamerally into rabbit eyes. Four chalcone derivatives, RVC-556 (2'-hydroxychalcone), RVC-574 (2'-hydroxychalcone hydrazone), RVC-574P (2'-hydroxychalcone phenyl hydrazone) and RVC-588 (4,4'-dihydroxy chalcone) were studied along with prednisolone at a dose of 10 mg/kg i.p. t.i.d. for their anti-inflammatory actions. RVC-574 was more active than prednisolone in inhibiting posterior uveitis by 65% and 43%, respectively. RVC-556, RVC-574P, and RVC-588 did not affect the posterior uveitis in rats. On the other hand, anterior ocular inflammation was inhibited by 1% eyedrops of RVC-556, RVC-574P and RVC-588 but not by RVC-574. RVC-556 was more active than; RVC-574P was less active than; and RVC-588 was about equiactive as prednisolone in inhibiting anterior ocular inflammation by 77%, 47%, 69%, and 64%, respectively.

Treatment of S antigen uveoretinitis with lipoxygenase and cyclo-oxygenase inhibitors

The role of metabolites of arachidonic acid (AA) in experimental autoimmune uveoretinitis was studied using inhibitors of AA metabolism. Nordihydroguaiaretic acid (NDGA), which inhibits predominantly the lipoxygenase (LO) pathway, or indomethacin, a specific cyclo-oxygenase (CO) inhibitor, was administered to rats immunized with retinal S antigen. Levels of various AA metabolites were measured in the inflamed uvea, and the severity of intraocular inflammation was quantitated by morphometric analysis. Histopathologically, the uveoretinitis was significantly suppressed following treatment with NDGA, while indomethacin treatment resulted in augmentation of the disease (p less than 0.05). These results tend to indicate that the inhibition of the LO rather than the CO pathway may be more beneficial in the treatment of autoimmune uveitis.

Uveitis and immune responses in primates immunized with IRBP-derived synthetic peptides

Monkeys immunized with bovine IRBP-derived synthetic peptides R4 (sequence 1158-1180) or R14 (1169-1191) developed EAU which was detected by both clinical and histological examinations. The inflammation localized mainly in the choroid, with only minor changes being noticed in the adjacent retinal tissue. EAU developed in only one of the two monkeys immunized with each of the peptides and the animals with disease also showed higher levels of cellular immunity toward the immunizing peptide than did the monkeys with no disease. The cellular immune responses, measured by the lymphocyte proliferation assay, were specific toward the immunizing peptides, with no cross responsiveness to whole IRBP. This finding suggests that the two uveitogenic peptides were non-immunodominant in the tested monkeys. In contrast, peptide R14 is highly immunodominant in the Lewis rat. Also, the fine specificity of the monkey response to R14 differed from that of the Lewis rat. The possible genetic control of the monkey susceptibility to EAU induction by the peptides is discussed and the unique finding of an autoimmune disease induction by a non-immunodominant peptide is underscored.

Comparison of clinical and experimental uveitis

Uveitis is a term which encompasses many clinical syndromes which would appear to be discrete entities. Both clinically and experimentally, the separation of uveitis affecting only the anterior segment from that affecting the posterior segment has a sound pathogenetic basis. However, clear distinctions among the various forms of endogenous posterior uveitis are more difficult to maintain in the light of evidence from experimental models of autoimmune uveitis (EAU). EAU can be induced by a variety of retinal antigens and each antigen has been shown to induce somewhat different forms of EAU, depending on such factors as dose of antigen, species and strains of animal model, and the type(s) of adjuvant used. However, within each model a similar spectrum of uveoretinal responses can be induced by each antigen suggesting that the pathogenetic mechanisms are probably similar also. In addition, if these models are analogous to human disease, then each clinical entity within this apparently heterogeneous group of clinical posterior uveitis syndromes may represent one aspect of a general organ-specific uveoretinal response to autoantigens.