In vivo and in vitro IL-18 production during uveitis associated with Behçet disease: effect of glucocorticoid therapy.

Uveitis represents one of the major diagnostic criteria in Behçet's disease. It is most prevalent in the countries of the Mediterranean area, including Algeria, and along the Silk Road. Clinical features include oral and genital ulcers, ocular and skin lesions, as well as central nervous system, joint, vascular, gastrointestinal, or pulmonary manifestations. Many studies have reported that Th1 immune responses are involved in the physiopathology. We have previously studied the production of IL-12 and IFN-γ, cytokine markers in the Th1 pathway involved in Behçet's disease. In our study, we investigate in vivo and in vitro IL-18 production in Algerian patients with Behçet's disease with ocular manifestations in various stages of the disease. We examined the effect of glucocorticoids on IL-18 production during the active stage of the disease. Our results suggest that IL-18 could be a good biomarker for monitoring disease activity and its regression, demonstrating the effectiveness of treatment on the underlying immunopathologic process.

[Effects of peroxynitrite derived from nitric oxide on cultured bovine ocular explants]. / Effets du peroxynitrite dérivé du monoxyde d'azote sur des explants oculaires bovins en culture.

INTRODUCTION: Several studies have reported a significant production of nitric oxide (NO) with peroxynitrite formation in the setting of intraocular inflammation. In a previous study, we showed the cytotoxic effect of nitrites and nitrates, stable metabolites of NO, on the various tissues forming the layers of the eye, with variable degrees of tissue sensitivity. This study aims to investigate the effect of peroxynitrite on whole ocular bovine explants in culture. METHODS: Healthy ocular bovine eyes, obtained immediately upon enucleation, were dissected and samples were taken from the anterior and posterior segments, and then cultured in DMEM supplemented with 10% fetal bovine serum, 2mM L-glutamine and antibiotics. Cultures were treated with 3-morpholino-sydonimin N-ethyl-carbamide (SIN-1) (molecule which produces NO and superoxide anion O(2)(.-)) at varying concentrations (100 to 500 µM) over 24 hours. After incubation, the explants were fixed in 10% buffered formalin, and histological study was performed. RESULTS: Most of the structures showed changes on tissue and cellular levels after incubation with the peroxynitrite donor and various responses depending on the concentration used. These observations reflect variable concentration-dependent tissue sensitivity. The epithelia (cornea, iris and ciliary process) showed high sensitivity in comparison with sclera, which developed greater resistance. CONCLUSION: In all, our results indicate a deleterious effect of peroxynitrite on bovine ocular structures in vitro. This effect is proportional to the concentration used. These results corroborate those reported by other teams and suggest the role of peroxynitrite derived from NO in the ocular lesions observed in the setting of uveitis.

[Deleterious effects of stable nitric oxide derivatives, a uveitis inflammatory marker, on cultured bovine ocular layers]. / Effets délétères des dérivés stables du monoxyde d'azote, marqueur inflammatoire des uvéites, sur les différentes tuniques de l'oeil de boeuf en culture.

INTRODUCTION: Uveitis is an intraocular inflammation affecting various eye segments. This disease is characterized by a high level of nitric oxide production. It is estimated via the quantification of its end products: nitrites and nitrates. In a previous study, we showed the cytotoxic effect of these molecules on bovine retina in vitro. In this study, we investigated the effect of these two molecules on cultured ocular explants in vitro. METHODS: After clinical examination, healthy bovine eyes were obtained immediately after enucleation and were transported to the laboratory at +4 degrees C. After dissection, ocular explants from anterior and posterior segments were cultured in DMEM supplemented with 10% of FBS, 2mM glutamine, 100UI penicillin, and 100UI/ml streptomycin. Cultures were treated with either nitrites or nitrates at different concentrations (300-500 microM). After culture incubation (24-48h), ocular explants were fixed in buffered formalin and the histological study was performed. RESULTS: All structures showed structural alterations in relation with culture duration and molecule concentrations. The different structures showed different degrees of sensitivity depending on the type and concentration of the metabolite used. Sclerotic analysis showed very little response to the two molecules, whereas the cornea and ciliary process epithelia showed the highest sensitivity. CONCLUSION: Our results showed a cytotoxic effect of nitrites and nitrates on ocular structures in vitro. This effect was correlated with molecule concentration and duration of exposure. The structural alterations observed suggest that nitric oxide, via its products, is implicated in the ocular lesions observed during uveitis.

[Effect of corticotherapy on interleukin-8 and -12 and nitric oxide production during Behçet and idiopathic uveitis]. / Effet de la corticothérapie sur la production des interleukines 8, 12 et du monoxyde d'azote au cours des uvéites Behçet et idiopathique.

OBJECTIVES: To investigate the effect of corticotherapy on IL-8, IL-12, and nitric oxide (NO) production during idiopathic and Behçet active uveitis. METHODS: Peripheral venous blood was drawn from 70 patients with active uveitis before and during corticotherapy (32 with Behçet uveitis and 38 with idiopathic uveitis) and from 30 controls. Plasma was collected and peripheral blood mononuclear cells were separated immediately and cultured with or without Concanavaline A. IL-8 and IL-12 levels in plasma and culture supernatants were measured by specific enzyme-linked immunosorbent assay (ELISA). Nitric oxide levels were evaluated using a modified Griess method. RESULTS: Before therapy, the two groups of patients showed highly significant elevation of IL-8, IL-12, and NO levels compared to control subjects. During therapy, IL-8 and nitric oxide levels were significantly lower in active idiopathic and Behçet active uveitis both in vivo and in vitro. This effect was correlated with therapy duration. In contrast, while significant reduction of IL-12 levels was observed both in vivo and in vitro in idiopathic active uveitis during therapy, this effect was observed in vitro in Behçet active uveitis but not in vivo. CONCLUSION: Our results suggest that IL-8, IL-12, and NO are involved in the physiopathological mechanisms of idiopathic and Behçet uveitis. These three molecules showed different degrees of sensitivity to the inhibitory effect of corticoids, reflecting their different regulation by corticotherapy during active phases of the two diseases. According to our study, IL-8 can serve as a marker of inflammatory responses, while IL-12 should be used as a marker of the specific immune responses during active uveitis.