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      Expression of TLR4-MyD88 and NF- κB in the Iris during Endotoxin-Induced Uveitis

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          Abstract

          Purpose. To observe the expression of Toll-like receptor-4 (TLR4), myeloid differentiation factor 88 (MyD88), and nuclear factor kappa B p65 (NF- κB p65) in iris tissue during endotoxin-induced uveitis (EIU) and evaluate the significance of these factors in uveitis. Methods. Wistar rats were randomly divided into 5 groups (0 h, 12 h, 24 h, 48 h, and 72 h, n = 10/group). Animal model of acute anterior uveitis was established by a hind footpad injection of 200  μg Cholera vibrio LPS. Expression of TLR4, MyD88, and NF- κB p65 in iris ciliary body tissue was detected through immunohistochemical staining. Results. Expression of TLR4 was not detected in normal iris-ciliary body complex, TLR4 positive cells with round morphology appeared in the iris stroma 12 hours after injection, significantly increased ( P < .001) 48 hours after injection, and decreased gradually 72 hours after injection. Expression of MyD88 and NF- κB p65 is consistent with the change of the TLR4. Conclusions. The increased expression of TLR4 and its downstream signal transduction moleculesMyD88, NF- κB p65 indicate the potential role of pathway in the pathogenesis of acute anterior uveitis (AAU).

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          Most cited references14

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          Endotoxin-induced uveitis in rats as a model for human disease.

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            Effects of blue honeysuckle (Lonicera caerulea L.) extract on lipopolysaccharide-induced inflammation in vitro and in vivo.

            The aim of the present study was to investigate the effects of blue honeysuckle extract (BHE), which contains high level of phenolic compounds, on endotoxin-induced uveitis (EIU). Male Lewis rats were randomly divided into 5 groups with 14 rats in each (eight rats for collection of aqueous humor, six rats for histologic examination). EIU was induced by a footpad injection of lipopolysaccharide (LPS). 1, 10, or 100 mg of BHE was injected intravenously immediately after LPS injection. The aqueous humor was collected at 24 h after LPS injection, the number of infiltrating cells, protein concentration, nitric oxide (NO), tumor necrosis factor (TNF)-alpha, and prostaglandin (PG)-E2 levels in the aqueous humor were determined. Some eyes were enucleated for histologic examination and immunohistochemical analysis. Immunohistochemical staining with a monoclonal antibody against activated nuclear factor (NF)-kappaB was performed to evaluate the effect of BHE on NF-kappaB activation. To further clarify the anti-inflammatory effect, RAW264.7 cells (a mouse macrophage cell line) were stimulated with LPS in the presence or absence of BHE and its major phenolics, cyanidin 3-glucoside (C3G), cyanidin 3-rutinoside (C3R), chlorogenic acid (CA). Expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) were analyzed by Western blot method. BHE treatment significantly reduced the inflammatory cell infiltration, the protein concentration, the levels of NO, TNF-alpha and PGE2 in the aqueous humor and improved histologic status of the ocular tissue. The number of activated NF-kappaB-positive cells was lower in the iris-ciliary body treated with BHE at 3 h after LPS injection. BHE significantly suppressed the production of NO, PGE2 and TNF-alpha in the culture medium as well as the expression of iNOS and COX-2 by LPS-stimulated RAW264.7 cells in a dose-dependent fashion. C3G, C3R and CA showed no or weak inhibitory effects on the level of inflammatory mediators and the expression of iNOS and COX-2. These results suggest that BHE attenuates the degree of inflammation in eyes with EIU by inhibiting the NF-kappaB dependent signaling pathway and the subsequent production of proinflammatory mediators.
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              Essential role of the MyD88 pathway, but nonessential roles of TLRs 2, 4, and 9, in the adjuvant effect promoting Th1-mediated autoimmunity.

              Induction of tissue-specific experimental autoimmune diseases involves an obligatory adjuvant effect to trigger an innate response of a type that will drive a Th1-biased adaptive response. This is achieved by use of CFA containing mycobacteria (Mycobacterium tuberculosis), whose recognition by cells of the innate immune system depends on TLRs that signal through the adaptor molecule MyD88. We examined the role of selected components of the MyD88 pathway in promoting experimental autoimmune uveitis (EAU). Mice deficient in MyD88, TLR2, TLR4, or TLR9 were immunized with the retinal Ag interphotoreceptor retinoid-binding protein in CFA, and their EAU scores and associated immunological responses were examined. MyD88-/- mice were completely resistant to EAU and had a profound defect in Th1, but not Th2, responses to autoantigen challenge. Surprisingly, TLR2-/-, TLR4-/-, and TLR9-/- mice were fully susceptible to EAU and had unaltered adaptive responses to interphotoreceptor retinoid-binding protein. Examination of IL-1R family members, which share the common adaptor MyD88 with the TLR family, revealed that IL-1R-deficient mice, but not IL-18-deficient mice, are resistant to EAU and have profoundly reduced Th1 and Th2 responses. These data are compatible with the interpretation that TLR9, TLR4, and TLR2 signaling is either not needed, or, more likely, redundant in the adjuvant effect needed to induce EAU. In contrast, signaling through the IL-1R plays a necessary and nonredundant role in EAU and can by itself account for the lack of EAU development in MyD88 mice.
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                Author and article information

                Journal
                Mediators Inflamm
                MI
                Mediators of Inflammation
                Hindawi Publishing Corporation
                0962-9351
                1466-1861
                2010
                3 August 2010
                : 2010
                : 748218
                Affiliations
                1Departmnet of Ophthalmology, Beijing Chaoyang Hospital, Capital Medical University, No. 8 Baijiazhuang Road, Chaoyang District, Beijing 100020, China
                2Department of Ophthalmology, Haidian Maternal and Child Health Hospital, Tonji Medical University, Beijing 100080, China
                Author notes

                Academic Editor: Philipp M. Lepper

                Article
                10.1155/2010/748218
                2929509
                20847811
                5e0a6775-2e9d-4f7b-98b5-d0509ed49ea1
                Copyright © 2010 Shang Li et al.

                This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 25 November 2009
                : 21 June 2010
                Categories
                Research Article

                Immunology
                Immunology

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