Genia Maftzir

Serum levels of interleukin-2 receptor in ocular Behçet's disease

Serum interleukin-2 receptor levels were evaluated in 69 patients who had chronic bilateral uveitis and in 22 control subjects. Fifty-one of the 69 patients with uveitis had the ocular type of Behçets disease and 18 had pars planitis (intermediate uveitis). The mean serum interleukin-2 receptor level was 412.6 +/- 94.6 U/ml for the control group, 465.0 +/- 96.6 U/ml for the patients with intermediate uveitis, and 810.9 +/- 369.3 U/ml for those with ocular Behçets disease. The serum interleukin-2 receptor levels of patients with ocular Behçets disease were significantly different from the levels of both the control and the intermediate uveitis groups (P < .001). The differences in serum levels of patients with intermediate uveitis and the levels of the control subjects were not statistically significant. Treatment of patients with ocular Behçets disease for four to six weeks with either cyclosporine, methylprednisolone, or a combination of both, decreased the intraocular inflammation in nearly all cases. The influence of treatment on the level of serum interleukin-2 receptor, however, was variable.

Blood serum interleukin-1 receptor antagonist in pars planitis and ocular Behçet disease.

PURPOSE To determine the levels of interleukin-1 receptor antagonist (IL-1ra) in the blood serum of patients with idiopathic bilateral pars planitis and Behçet disease. METHODS Five milliliters of blood was with-drawn from the cubital vein of 91 patients (58 with the ocular type and five with the combined type of Behçet disease; 28 with pars planitis) and 36 volunteers. Serum was separated from these samples and stored at -70 C until assayed. Interleukin-1 receptor antagonist levels were determined by human IL-1ra enzyme-linked immunosorbent assay kits. In patients not receiving any systemic medication, one serum sample was obtained before initiating treatment and another when the patients had been under full medical treatment for 6 weeks or more. RESULTS Pretreatment mean +/- SD serum IL-1ra levels were 320 +/- 32 pg/ml for the patients with pars planitis, 380 +/- 54 pg/ml for patients with Behçet disease, and 271 +/- 29 pg/ml for the control subjects (no statistical significance). During treatment, a mean serum level of 352 +/- 37 pg/ml was observed in patients with pars planitis (not significantly different from control subjects) and 538 +/- 79 pg/ml in patients with ocular Behçet disease (P = .0116 compared with control subjects). The greatest increase in IL-1ra levels was observed in patients with Behçet disease who received a combination of cyclosporine and corticosteroids. CONCLUSIONS Because IL-1ra is one of the natural immunomodulating molecules, the significant increase of serum IL-1ra levels, especially after combined treatment with cyclosporine and corticosteroids, could indicate that the therapeutic effects of this regimen may be mediated through its effects on this molecule.

Cellular and humoral immune parameters among patients with retinitis pigmentosa and other retinal disorders

Patients with retinitis pigmentosa, other retinal degenerations and a group of normal volunteers were included in a masked study designed to examine the existence of autoimmune reactions toward retinal antigens and the possible defect in lymphokine production (IL-1, IL-2 and gamma interferon). The results obtained did not show any specific anamnestic response to the retinal S-Ag nor any outstanding defect in gamma interferon production by the lymphocytes of patients with retinitis pigmentosa. It is suggested that a larger masked study be conducted as soon as possible in order to clarify these aspects of immune aberrations in patients with retinitis pigmentosa.

The Rabbit Cornea - a Model for the Study of Angiogenic Factors

The avascular cornea has ideal organ characteristics for the study of angiogenic stimuli. Indeed, early on, Michaelson and colleagues used the rabbit cornea to study the effect of heat injury (1,2) and to analyze the basic histological and possible chemical phenomena involved in neovascularization (3,4). Later, a more meticulous approach to the study of neovascular stimuli was devised by Zauberman and colleagues (5) and used also by Folkman’s group (6) studying the “Tumor Angiogenic Factor” (TAF). Although the corneal model had many advantages, it became evident that the variability among experiments was very large. Furthermore, the possibility that cornea vascularization could be induced by “nearly everything” (7, Zauberman - personal communication) prompted us to look for a reliable and reproducible methodology for the study of neovascular factors.

Angiogenesis and Interleukins

Vascularization of tissues is a normal event during embryogenesis and healing-repair processes. In the eye, early vascularization of the vitreous cavity by the hyaloid system is later replaced by the definite retinal/choroidal vessels. The former system involutes (1) leaving the vitreous cavity and lens clear and devoid of direct vascularization. In various pathological conditions, however, neovascularization of avascular ocular tissues is triggered (2). In an attempt to elucidate the basic mechanisms involved in ocular angiogenesis, the possible role of leukocytes and leukocyte products were investigated. Early on, it became evident that cellular and humoral factors of immune reactions could stimulate neovascular processes (3–5). Following these findings, a panel of purified compounds was examined and the possible regulating role of prostaglandins in angiogenesis unveiled (6,7). Although early studies indicated that lymphokines and/or monokines are involved in the stimulus of neovascularization (4,5,8), the lack of purified isolates prevented further clarification. Recently, recombinant interleukin-1 (IL-1) and interleukin-2 (IL-2) became available. In this study, we are reporting our findings on the effect of IL-l and IL-2 on angiogenesis of ocular tissues.

Ocular distribution of the chimeric protein IL2-PE40

A construct of IL-2 and pseudomonas exotoxin (PE40) has been genetically engineered. An aliquot of 100 microliter of the chimeric protein, radiolabelled with I125, was administered to healthy rats by various routes. At different intervals, ocular and non ocular tissues were removed and the levels of the radiolabelled chimeric protein IL-2-PE40 measured. Systemic administration of IL2-PE40 either intravenously (IV) or intraperitoneally (IP) leads to high levels of the drug in the blood, liver and spleen. Little or no radioactivity is observed within the ocular tissues using this route. On the other hand, local administration of the drug either as subtenon injection or as eye drops resulted in a very high concentration of the drug within the conjunctiva, cornea and sclera, with little radioactivity detected systemically. Subtenon injection induced a significant drug level within the optic nerve. With the drops, the chimeric protein was also detected, in low levels, intraocularly.

Inhibition of Neovascular Stimuli

Clinical and experimental observations regarding the conditions under which ocular neovascularization is triggered led us to postulate that angiogenic factors are most probably normal tissue metabolites (1). These metabolites are produced in high levels under certain stress conditions of the affected tissues. When the concentration reaches a stimulating level, neovascularization is induced (1,2). Corneal neovascularization stimulated by controlled cauterization of the corneal tissue could be affected by the administration of steroids during the process (3). Furthermore, indomethacin, an inhibitor of prostaglandin synthesis, decreased significantly the extent of neovascularization induced by epidermal growth factor (EGF), fibroblast growth factor (FGF), lipopolysaccharide (LPS) and prostaglandin (PGE1). However, in most cases indomethacin did not abolish completely the angiogenic stimulus even in very high concentrations (4). More recently, tumor and corneal vascularization have been inhibited using a combination of heparin and cortisone (5,6). We report herein our observations regarding the effect of various antimetabolites, steroids/indomethacin and aqueous humor on various angiogenic stimuli.

Heterogenous expression of antigenic markers on retinoblasts.

Using a large panel of monoclonal antibodies to antigenic determinants specific for photoreceptor outer segments (S-Ag), for cells of neural (Leu-7) bipolar and/or ganglion cell (A2B5), glial/astrocytic (LN-1) or Mullers cell (M.M.) and two polyclonal antibodies to S-Ag and S-100 protein, the authors studied the expression of these antigenic determinants in four newly established retinoblastoma cell cultures and in cells derived from the Y-79 cell line. All four newly established retinoblastoma cell cultures demonstrated antigenic determinants specific for photoreceptors, astrocyte/glial and Mullers cells. The population of cells derived from the Y-79 cell line reacted mainly with the polyclonal antibody to S-100 protein, reflecting the homogeneity of its cell population mainly harboring antigenic determinants specific for astrocyte/glial cells. The heterogeneic staining of the newly established retinoblastoma cell cultures may reflect the multipotential-embryonic origin of these cells demonstrated by their ability to express antigenic determinants specific for the different cellular elements of the mature neuro-retina while the strictly glial staining of the Y-79 may be the result of cloning of this cell line.

LYMPHOCYTE ACTIVITY AND THE ROLE OF HUMORAL FACTORS IN PATIENTS WITH CHRONIC OCULAR INFLAMMATION

Chronic ocular inflammation is one of the important causes leading to vascularization (1–3). Humoral factors derived from activated leukocytes have been found to be angiogenic in the rabbit cornea (1). The possible relationship between substances released during chronic inflammatory processes and neovascularization could explain the neovascularization of ocular tissues observed in chronic uveitis and Behcet’s disease (4). With the emergence of Cyclosporin A as a potent immunomodulator that influences mainly the release of interleukins (5), its use in ophthalmology is being investigated (6,7). We report herein the effect of Cyclosporin A and steroid treatment on the lymphocyte activity and the release of humoral factors of patients with chronic uveitis and Behcet’s disease treated with these drugs.

Cytokines and Growth Factors. Early Gene Expression During Angiogenic Stimuli

From accumulating experimental observations, it has become evident that angiogenesis — the sprouting of new blood vessels from other mature vessels — can be induced by a myriad of angiogenic factors1,2. Despite their potential roles in initiating the process, these factors, most probably, influence a single (or a few) events within a very complex cascade of pathways which finally lead to angiogenesis as observed in vivo1.