Expression of class II antigen in endotoxin induced uveitis

Uveitis can be induced by systemic or intravitreal administration of endotoxin (lipopolysaccharide, LPS). In this study we correlated the expression of class II antigens (la in rat) of the Major Histocompatibility Complex (MHC), with this experimental model of uveitis. Ia antigen was detected by immunohistochemistry using the Avidin-Biotin-Peroxidase Complex (ABC) method and the monoclonal antibody OX6. Ia antigen was not expressed in normal eyes. However, Ia was expressed in the anterior uvea epithelial cells in all eyes with LPS induced uveitis. This study demonstrates that the ocular Ia expression is a localized process in the anterior uvea in response to systemic or intravitreal LPS. This response appears to be distinct from the action of LPS on macrophage Ia expression, where LPS has been shown to inhibit the induction of Ia antigen in macrophages by gamma interferon.

Pro-angiogenic effect of IFNgamma is dependent on the PI3K/mTOR/translational pathway in human retinal pigmented epithelial cells

Background

Mutations in COL8A2 gene which encodes the collagen alpha-2 (VIII) chain have been identified in both familial and sporadic cases of Fuchs endothelial corneal dystrophy (FECD). Heterozygous mutations in the SLC4A11 gene are also known to cause late-onset FECD. Therefore we screened for COL8A2, SLC4A11 gene variants in Indian FECD patients.

Methods

Eighty patients with clinically diagnosed FECD and 100 age matched normal individuals were recruited. Genomic DNA was isolated from peripheral blood leukocytes. Mutations in COL8A2, SLC4A11 coding regions were screened using bi-directional sequencing. Fischer's exact test or Pearson's chi squared test were used to predict the statistical association of genotypes with the phenotype.

Results

Screening of COL8A2 gene revealed 2 novel c.1610G>A, c.1643A>G and 3 reported variations c.112G>A, c.464G>A and c.1485G>A. In SLC4A11 gene, novel c.1659C>T, c.1974C>T and reported c.405G>A, c.481A>C and c.639G>A variants were identified. However all the variations in both the genes were also present in unaffected controls.

Conclusions

This is the first study analysing COL8A2 gene in Indian patients with FECD. No pathogenic mutations were identified in COL8A2. Merely silent changes, which showed statistically insignificant association with FECD, were identified in the screening of SLC4A11 gene. These results suggest that COL8A2, SLC4A11 genes may not be responsible for FECD in patients examined in this study.

Expression of cell adhesion molecules in corneal graft failure

Corneal graft failure is frequently mediated by uncontrolled inflammatory disease. We studied the expression of cell adhesion molecules in seven penetrating keratoplasty specimens with graft failure and in a normal eye bank cornea using immunohistochemical staining and monoclonal antibodies against intercellular adhesion molecule-1 (ICAM-1, CD54), lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and major histocompatibility complex (MHC) class II antigen (HLA-DR). ICAM-1 and HLA-DR were expressed on keratocytes and the corneal endothelium in six of the seven specimens. ICAM-1 expression was strongest in the corneas with the most severe inflammation (corneal allograft rejection and severe intraocular inflammation). LFA-1 is a counter-receptor for ICAM-1, and infiltration with leukocytes expressing either the alpha or beta chain of LFA-1 was found in areas of ICAM-1 expression in four of the seven corneas. In contrast, E-selectin was expressed in the stroma in only two specimens, and VCAM-1 in one specimen. Expression of cell adhesion molecules or MHC class II antigen were not detected in the normal eye bank cornea. These data suggest that ICAM-1 expression may play an important role in the development of corneal graft failure. Furthermore, monoclonal antibodies to block ICAM-1 or its ligands may inhibit the development of corneal inflammation.

Cytokine-dependent modulation of oral tolerance in a murine model of autoimmune uveitis

In summary, our data suggest that oral tolerance in the mouse EAU model may occur by anergy/deletion or by suppression, depending on the feeding regimen. Tolerance involving putative regulatory cells appears to require the ability to produce both IL-4 and IL-10, whereas induction of tolerance involving anergy may not require the presence of Il-4 and IL-10. We propose that regulatory cells induced by three feedings of IRBP can be selectively enhanced through the use of cytokines. From the point of view of clinical therapy, it would be worthwhile to explore postimmunization feeding regimens involving administration of IL-4 and IL-10.

Immunohistochemistry and electron microscopy of cyclitic membrane. Report of a case

An immunohistochemical study using various antibodies directed against antigens of inflammatory cells, neurons, and Müller cells, interstitial collagens (types I and III), basement membrane collagens (types IV and V), and basement membrane glycoproteins (laminin and fibronectin) was performed to characterize the components of two cyclitic membranes (in an enucleated eye and a surgical specimen) from a 15-year-old patient with an eight-year history of chronic bilateral uveitis. When specimens were obtained, no inflammation was seen clinically. Correlative light and electron microscopic examinations were also performed on one specimen. The preponderant cells in the cyclitic membrane were glial cells. The preponderant extracellular tissue within the cyclitic membrane consisted of basement membrane components. These observations suggest that cyclitic membranes could be formed mainly by the extension of proliferative glial elements from the retina, with a minor component derived from fibroblasts.

Role of chorioretinal biopsy in inflammatory eye disease

Two patients who had similar clinical presentations of bilateral multiple chorioretinal lesions and needed a correct diagnosis underwent chorioretinal biopsy. The biopsy from one patient demonstrated mainly a B cell infiltrate in choroidal and subretinal nodules, while the biopsy from the second patient showed mainly macrophages in the retina. These findings directed the therapeutic approach taken in each patient. Although chorioretinal biopsy is an invasive procedure with the potential for serious complications, the resultant finding may aid in the diagnosis and guide the subsequent management of certain patients presenting with serious ocular findings of undefined etiology.

Association between mast cells and the development of experimental autoimmune uveitis in different rat strains

To study the role of anterior uveal mast cells in experimental autoimmune uveitis (EAU), the mast cells in the iris and ciliary body of Lewis rats, Brown Norway (BN) rats, and their F1 hybrids (LBNF1) were quantitated in normal rats and during the induction period of EAU. The mean baseline mast cell number was 68.9 +/- 10.8 per anterior uvea for Lewis rats, 0.3 +/- 0.2 for BN rats, and 4.6 +/- 0.6 for LBNF1 rats. Detectable mast cells in the anterior uvea of S-Ag-immunized Lewis rats decreased to 60% of control at 6 days postimmunization, recovered to 80% at 10 days, and dropped again to 16% at 13 days, with disease onset around 14 days. In Lewis rats that were adoptively transferred with a uveitogenic T-lymphocyte line, a profound drop in anterior uveal mast cell numbers occurred in the eyes with early signs of EAU, 3 days after the transfer. The decrease in detectable mast cells is consistent with mast cell degranulation. The data suggest that anterior mast cells participate in the immunopathogenesis of EAU and may influence the genetic susceptibility to EAU.

Comparison Between Methotrexate and Mycophenolate Mofetil Monotherapy for the Control of Noninfectious Ocular Inflammatory Diseases

PURPOSE

To compare mycophenolate mofetil (MMF) to methotrexate (MTX) as corticosteroid-sparing therapy for ocular inflammatory diseases.

DESIGN

Retrospective analysis of cohort study data.

METHODS

Participants were identified from the Systemic Immunosuppressive Therapy for Eye Diseases Cohort Study. Demographic and clinical characteristics were obtained via medical record review. The study included 352 patients who were taking single-agent immunosuppression with MTX or MMF at 4 tertiary uveitis clinics. Marginal structural models (MSM)-derived statistical weighting created a virtual population with covariates and censoring patterns balanced across alternative treatments. With this methodological approach, the results estimate what would have happened had none of the patients stopped their treatment. Survival analysis with stabilized MSM-derived weights simulated a clinical trial comparing MMF vs MTX for noninfectious inflammatory eye disorders. The primary outcome was complete control of inflammation on prednisone ≤10 mg/day, sustained for ≥30 days.

RESULTS

The time to success was shorter (more favorable) for MMF than MTX (hazard ratio = 0.68, 95% confidence interval: 0.46-0.99). Adjusting for covariates, the proportion achieving success was higher at every point in time for MMF than MTX from 2 to 8 months, then converges at 9 months. The onset of corticosteroid-sparing success took more than 3 months for most patients in both groups. Outcomes of treatment (MMF vs MTX) were similar across all anatomic sites of inflammation. The incidence of stopping therapy for toxicity was similar in both groups.

CONCLUSIONS

Our results suggest that, on average, MMF may be faster than MTX in achieving corticosteroid-sparing success in ocular inflammatory diseases.

Effects of topical FK506 on endotoxin-induced uveitis (EIU) in the Lewis rat

FK506 is a macrolide antibiotic and a potent immunosuppressant. To investigate the effect of topical FK506 on acute ocular inflammation, we evaluated its action on the development of endotoxin-induced uveitis (EIU). At two different concentrations of 0.05% and 0.3%, topical FK506 was applied to Lewis rats with EIU. In aqueous, the mean number of inflammatory cells per microliter +/- SEM was 2,389 +/- 1,277, 1,571 +/- 1,562, 898 +/- 882, and 69 +/- 152 for rats treated with vehicle alone, 0.05%, 0.3% FK506, and 1% prednisolone acetate. The median of histological grades was 2, 1.5, 0.8, and 0.5 for animals treated with these 4 different regimens respectively. Analysis of aqueous protein showed a small reduction in FK506-treated animals. Mean blood levels of FK506 were low in rats treated with topical FK506 (0.05%, 0.84 ng/ml; 0.3%, 2.0 ng/ml) suggesting that its therapeutic effect was not secondary to the systemic absorption of the drug. Although FK506 is not as effective as prednisolone, 0.3% FK506 produced significant decreases in the mean aqueous inflammatory cell number and histological inflammatory score as compared to control vehicle alone. We conclude that topical FK506 can suppress EIU in a dose-dependent fashion and may be an alternative medication for patients with anterior uveitis and contra-indication to topical steroid.

Combined use of cyclosporine and ketoconazole in the treatment of endogenous uveitis

Ten patients with endogenous uveitis were in clinical remission attributable to treatment with cyclosporine and prednisone. After the cyclosporine dose was reduced by two thirds, these patients were randomly assigned to treatment with or without ketoconazole, a potent inhibitor of cytochrome P-450, in a double-masked placebo-controlled study. The dose was reduced over three days. During a three-month follow-up, no patients treated with ketoconazole had a relapse of uveitis, while four of six (66%) control subjects had a flare-up. Toxicity in the ketoconazole-treated group was limited to a transient decrease in glomerular filtration rate (20% from baseline) at one month in two of six (33%) patients. Renal function was stabilized by further reduction of the cyclosporine dose.

Vitamin E in the treatment of uveitis-associated macular edema

PURPOSE

To investigate whether high-dose alpha-tocopherol (vitamin E) could reduce vision loss and retinal thickening associated with uveitis-associated cystoid macular edema.

DESIGN

A double-masked, randomized study.

METHODS

Uveitis patients with macular edema seen at the NIH were randomized and received either 1600 IU/day of vitamin E or placebo for 4 months. Visual acuity and retinal thickening were collected for the efficacy and the safety of the high dose of vitamin E.

RESULTS

Changes in visual acuity and retinal thickening.

CONCLUSIONS

Four-month oral supplementation with 1600 IU/d of vitamin E had no apparent effect on uveitis-associated macular edema or visual acuity in this small study.

HTLV-1 Infection of Human Retinal Pigment Epithelial Cells and Inhibition of Viral Infection by an Antibody to ICAM-1

PURPOSE

To examine whether human T-cell leukemia virus type 1 (HTLV-1) could infect a human retinal pigment epithelial (RPE) cell line, ARPE-19, in vitro and to investigate its regulation.

METHODS

A coculture system with ARPE-19 and irradiated cells of an HTLV-1-producing T-cell line, MT2 was used to determine the permissivity of RPE to HTLV-1 infection in vitro. The susceptibility to HTLV-1 was assessed by detection of viral DNA using the polymerase chain reaction (PCR), viral mRNA transcripts with reverse transcription PCR (RT-PCR) and viral antigen by immunofluorescence staining. An HTLV-1 Tax-activated HTLV-LTR-luciferase reporter assay was developed to measure viral infection quantitatively. The ICAM-1 expression on cocultured ARPE-19 cells was detected by flow cytometry and an ICAM-1-neutralizing antibody was used to test ICAM-1's role in the HTLV-1 infection of ARPE-19 cells. The regulation of HTLV-1 infection was investigated by culturing ARPE-19 cells with proinflammatory cytokines.

RESULTS

HTLV-1 infected ARPE-19 cells in vitro. The infection correlated with elevated expression of intercellular adhesion molecule (ICAM)-1 on the surface of ARPE-19 cells. ICAM-1-neutralizing antibody dramatically inhibited viral infection. Furthermore, proinflammatory cytokines dramatically suppressed HTLV-1 viral infection.

CONCLUSIONS

The tropism of HTLV-1 to retinal pigment epithelium could provide an explanation for the pathogenesis of HTLV-1-related ophthalmic diseases. A better understanding of specific roles of proinflammatory cytokines in the development of ophthalmic diseases may be beneficial for treatment.

Iris inflammatory cells, fibronectin, fibrinogen, and immunoglobulin in various ocular diseases

Using immunohistochemical techniques, we analyzed the inflammatory cell subpopulation and the presence of fibronectin and immunoglobulin in iridectomy specimens from 50 patients with cataracts, glaucoma, and uveitis, and from ten normal eyes. The irises from patients with uveitis showed the highest numbers of T-lymphocytic infiltration compared with all other groups. Concentrations of fibronectin, fibrinogen, and immunoglobulins were significantly higher in the uveitic group compared with other diseases and normal controls. The irises from patients with glaucoma showed fewer infiltrating cells and less fibronectin and fibrinogen. Enhancement of major histocompatibility complex class II antigen HLA-DR expression was observed in all disease groups compared with controls. These findings suggest that in patients with uveitis and acute glaucoma the infiltrating T lymphocytes and the presence of fibronectin, fibrinogen, and immunoglobulins may contribute to the greater risk of postsurgical inflammation, leading to such problems as closure of the iridectomy. The enhancement of HLA-DR antigen expression in the iris may indicate abnormalities of iris resident cells seen in various diseases.

Immunohistochemistry of the inflammatory response in Propionibacterium acnes endophthalmitis

Specimens were obtained from two patients with culture-proven Propionibacterium acnes endophthalmitis who had undergone vitrectomy. Wright's and Giemsa stains were performed using cytospin preparations of the dilute vitreous and revealed a predominance of polymorphonuclear leukocytes (80% to 90%). The remaining inflammatory cells in the vitreous were mostly macrophages (10% to 15%); very few lymphocytes were present (less than 5%). Immunohistochemical studies using monoclonal antibodies confirmed the paucity of lymphocytes. Most lymphocytes were CD4+ helper/inducer T cells. Almost no CD8+ suppressor/cytotoxic T lymphocytes or B lymphocytes were found. The inflammatory response in these two patients is most characteristic of acute inflammation and consistent with an underlying bacterial infection, despite a clinical picture of persistent, low-grade inflammation. Infection with P acnes has been shown to inhibit CD8+ T cells and may play a role in the persistent inflammation in cases of P acnes endophthalmitis.

Factors predictive of remission of new-onset anterior uveitis

PURPOSE

To identify factors predictive of remission of inflammation in new-onset anterior uveitis cases treated at tertiary uveitis care facilities.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Patients seeking treatment at participating academic uveitis clinics within 90 days of initial diagnosis of anterior uveitis.

METHODS

Retrospective cohort study based on standardized chart review.

MAIN OUTCOME MEASURES

Factors predictive of remission (no disease activity without corticosteroid or immunosuppressive treatments at all visits during a 90-day period).

RESULTS

Nine hundred ninety eyes (687 patients) had a first-ever diagnosis of anterior uveitis within 90 days before initial presentation and had follow-up visits thereafter. The median follow-up time was 160 days. Systemic diagnoses with juvenile idiopathic arthritis (JIA; adjusted hazard ratio [aHR], 0.38; 95% confidence interval [CI], 0.19-0.74) and Behçet's disease (aHR, 0.10; 95% CI, 0.01-0.85) were associated with a lower incidence of uveitis remission. Cases of bilateral uveitis (aHR, 0.68; 95% CI, 0.54-0.87) and those with a history of cataract surgery before presentation (aHR, 0.51; 95% CI, 0.29-0.87) also had a lower incidence of remission. Regarding clinical findings at the initial visit, a high degree of vitreous cells at initial presentation was associated with a lower incidence of remission (for 1+ or more vs. none: aHR, 0.72; 95% CI, 0.55-0.95). An initial visual acuity of 20/200 or worse, with respect to 20/40 or better, also was predictive of a lower incidence of remission (aHR, 0.52; 95% CI, 0.32-0.86).

CONCLUSIONS

Factors associated with a lower incidence of remission among new-onset anterior uveitis cases included diagnosis with JIA, Behçet's disease, bilateral uveitis, history of cataract surgery, findings of 1+ or more vitreous cells at presentation, and an initial visual acuity of 20/200 or worse. Patients with these risk factors seem to be at higher risk of persistent inflammation; reciprocally, patients lacking these factors would be more likely to experience remission. Patients with risk factors for nonremission of uveitis should be managed taking into account the higher probability of a chronic inflammatory course.

Endotoxin-induced uveitis in the rat: a hypothesis for preferential involvement of the anterior uvea

Endotoxin-induced Uveitis (EIU) was produced in Lewis rats by footpad injection of Salmonella endotoxin. Protein and cells were measured both in the aqueous humor and in the cerebrospinal fluid (CSF) in order to examine if the inflammation was strictly limited to the anterior uvea. EIU was also induced in Fischer and Brown Norway rats and the inflammation was compared among the three strains. Although the function and structure of the choroid plexus is very similar to the ciliary body, no signs of inflammation were seen in the choroid plexus and the CSF. Among the 3 tested strains of rats, EIU was maximal in Lewis rats, less severe in Fischer rats and least pronounced in Brown Norway rats. It is thought that because of its specific microvascular structure, the ciliary body is specially prone to endotoxin induced inflammation. The amount of inflammation however depends on the genetic background of the animal.

Immunospecific suppression of encephalitogenic-activated T lymphocytes by chimeric cytotoxin IL-2-PE40

We examined the action of a chimeric protein, IL-2-PE40, on the development of a T cell-mediated disease of the central nervous system with numerous similarities to multiple sclerosis, experimental autoimmune encephalomyelitis (EAE). EAE is caused by IL-2 receptor-bearing T cells specific for myelin basic protein (BP). We report here that the treatment of Lewis rats with IL-2-PE40 delayed and shortened the course of EAE induced by BP in adjuvant and dramatically prevented EAE mediated by anti-myelin basic protein T line cells. The absence of paralytic signs, the absence of cell infiltration in the central nervous system, and the abatement of cellular immunity to myelin basic protein in the treated rats are direct consequences of the specific mechanism of action of IL-2-PE40. Our data support the notion that IL-2-PE40 may be efficient as an immunosuppressive agent for those disorders in which activated T cells play a crucial role.

Treatment of inflammatory macular edema with humanized anti-CD11a antibody therapy

PURPOSE

To evaluate the safety and efficacy of treating macular edema, secondary to noninfectious uveitis, with a humanized anti-CD11a antibody.

METHODS

Six patients received weekly subcutaneous treatments for 16 weeks according to this open-label, prospective, noncomparative phase I/II trial. Best corrected visual acuity (BCVA) and central macular thickness (CMT) were compared to baseline. Adverse events were recorded and assessed. Blood was sampled to assess the levels of CD56(bright) regulatory NK cells before initiation and after termination of the study.

RESULTS

No serious adverse events were reported by the patients. Patients' ages ranged from 22 to 82 years. Mean BCVA improvements were 6.7 ± 6.9 ETDRS letters in the worse eye and 1.7 ± 5.2 letters in the better eye. Mean CMT reductions were 128 ± 105 μm in the worse eye and 57 ± 68 μm in the better eye. Anti-CD11a antibody treatments resulted in an increase in the CD56(bright) regulatory NK cell population in the peripheral blood of the patients.

CONCLUSIONS

Anti-CD11a treatment improved visual function, reduced macular thickness, and increased the level of CD56(bright) regulatory NK cells in patients with uveitic macular edema refractory to other immunosuppressive medications. Targeting CD11a may be beneficial in treating other causes of macular edema.

Kinetics of corneal transplant rejection in the rat penetrating keratoplasty model

Kinetic changes of inflammatory cells and major histocompatibility (MHC) antigenic markers in syngeneic and allogeneic corneal grafts in rats were studied. Syngeneic grafts demonstrated mild inflammation in the first week with macrophages and T-helper/inducer cells found in a 2:1 ratio. By week 2 fewer macrophages were seen, and by week 4 no inflammatory cells were seen in the central graft. Central keratocytes and endothelium were negative for class II MHC expression. Significant inflammation persisted adjacent to the wound with macrophages and T-helper/inducer cells seen surrounding the sutures. Allogeneic grafts in the first week demonstrated mild inflammation with macrophages and T-helper/inducer cells in a 2:1 ratio. The central graft in week 2 had increased numbers of T-helper/inducer cells and T-suppressor/cytotoxic cells. By the third and fourth week, the T-suppressor/cytotoxic cells had become the major infiltrating cell. MHC class II antigens were seen on inflammatory cells, keratocytes, donor, and recipient endothelium.

The immunological basis of degenerative diseases of the eye

It has become clear that disorders that were once considered "degenerative" have complex mechanisms, with many having been shown to have immune mediation as part of the disease process. These include arteriosclerotic heart disease and Alzheimer's disease. Indeed, several ocular disorders that once fell into the "degenerative" category meet this criterion as well. Immune mediation has been shown to be a part of many of the most common ocular disorders, and not just that of uveitis, or ocular inflammatory disease.

Angiography with fluorescein-labeled dextrans in a primate model of uveitis

Sequential fluorescein angiography, using fluorescein-labeled dextran molecules of several different sizes, was carried out in monkeys with intraocular inflammation induced with interphotoreceptor retinoid-binding protein. The vascular leakage seen with the dextrans was compared with that seen with standard fluorescein sodium angiography. The angiograms demonstrated that different-sized leaks appear in the retinal vessels in adjacent areas during the course of the inflammation. Most retinal vessels leaked only fluorescein sodium and no dextran of any size, suggesting that it is the unbound fluorescein that leaks out of these vessels and not fluorescein bound to plasma albumin. It was not possible to tell by clinical examination which areas would leak the larger-molecular weight tracers. Ultrastructural studies of the veins leaking the dextrans revealed areas of abnormal endothelial tight junctions, whereas the tight junctions were normal in areas where leakage occurred with fluorescein alone.