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      Green Tea Extract Treatment Alleviates Ocular Inflammation in a Rat Model of Endotoxin-Induced Uveitis

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          Abstract

          Green tea extract (GTE) ingested by rats exerted anti-oxidative activities in various ocular tissues as shown in our previous studies. The present work investigated anti-inflammatory effects of GTE on endotoxin-induced uveitis (EIU). EIU was generated in adult rats by a footpad injection of 1 mg/kg lipopolysaccharide (LPS). Oral administration of GTE (550 mg/kg) was given one, two or four times after LPS injection. Twenty-four hours later, LPS produced severe hyperemia and edema in the iris. Immunocytochemical examinations showed an accumulation of infiltrating cells in the aqueous humor that were immunopositive for cluster of differentiation 43 (CD43) and CD68, markers for leucocytes and macrophages, respectively. Analyses of the aqueous humor showed an increase in pro-inflammatory mediators including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1). GTE treatments improved the clinical manifestations and reduced infiltrating cells and protein exudation in the aqueous humor, which were not observed under half dose of GTE (275 mg/kg). The number of CD68 positive macrophages residing in the iris and ciliary was also reduced. GTE suppressed production of TNF-α, IL-6 and MCP-1 in the aqueous humor, which was associated with a down-regulation of LPS receptor complex subunits, Toll-like receptor 4 (TLR-4) and CD14, and suppression of nuclear factor-kappa Bp65 (NF-κBp65) in the iris and ciliary body. Our findings show that GTE is a potent anti-inflammatory agent against the inflammation of EIU, and suggest a potential use in treatment of acute uveitis.

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          Most cited references 38

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          Incidence and prevalence of uveitis in Northern California; the Northern California Epidemiology of Uveitis Study.

          To determine the incidence and prevalence of uveitis in a large, well-defined population in Northern California. Cross-sectional study using retrospective database and medical record review. A group of 2070 people within 6 Northern California medical center communities (N = 731 898) who had a potential diagnosis of uveitis. The patient database of a large health maintenance organization (2 805 443 members at time of the study) was searched for all patients who, during a 12-month period, had the potential diagnosis of uveitis. Detailed quarterly gender- and age-stratified population data were available. Medical records of patients who potentially had uveitis and who were members of the 6 target communities were reviewed by 2 uveitis subspecialists to confirm the diagnosis of uveitis and to establish time of onset. Demographic and clinical data were gathered for patients meeting the clinical definition of uveitis. Incidence rates were calculated by using a dynamic population model. Prevalence rates were based on the mid-study period population. Presence and date of onset of uveitis. At midstudy, the population for the 6 communities was 731 898. During the target period, 382 new cases of uveitis were diagnosed; 462 cases of uveitis were diagnosed before the target period. These data yielded an incidence of 52.4/100 000 person-years and a period prevalence of 115.3/100 000 persons. The incidence and prevalence of disease were lowest in pediatric age groups and were highest in patients 65 years or older (P<0.0001). The prevalence of uveitis was higher in women than in men (P<0.001), but the difference in incidence between men and women was not statistically significant. Comparison between the group of patients who had onset of uveitis before the target period (ongoing uveitis) and the entire cohort of uveitis patients showed that women had a higher prevalence of ongoing uveitis than men and that this difference was largest in the older age groups (P<0.001). In this largest population-based uveitis study in the United States to date, the incidence of uveitis was approximately 3 times that of previous U.S. estimates and increased with the increasing age of patients. Women had a higher prevalence of uveitis than men, and the largest differences were in older age groups.
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            Lipopolysaccharide recognition: CD14, TLRs and the LPS-activation cluster.

            Recognition of bacterial lipopolysaccharide (LPS) by the innate immune system elicits strong pro-inflammatory responses that can eventually cause a fatal sepsis syndrome in humans. LPS-mediated activation of mammalian cells is believed to involve the interaction of LPS with lipopolysaccharide-binding protein (LBP) in the serum and, subsequently with CD14. Although there is no doubt that CD14 binds LPS, CD14 is not capable of initiating a transmembrane activation signal because it is a glycosylphosphatidylinositol (GPI)-anchored protein. Accumulating evidence has suggested that LPS must interact with a transmembrane receptor(s) that is responsible for signal transduction. Integrins CD11c and/or CD18, Toll-like receptors (TLRs), as well as CD55, have been suggested to serve this function. Recently, we have revealed that a signalling complex of receptors is formed following LPS stimulation, which comprises heat-shock proteins (Hsps) 70 and 90, chemokine receptor 4 (CXCR4) and growth differentiation factor 5 (GDF5). Taking into account the discovery of the TLRs and the LPS-activation cluster, we propose a new model of LPS recognition.
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              Novel lipid mediators and resolution mechanisms in acute inflammation: to resolve or not?

              Because inflammation is appreciated as a unifying basis of many widely occurring diseases, the mechanisms involved in its natural resolution are of considerable interest. Using contained, self-limited inflammatory exudates and a systems approach, novel lipid-derived mediators and pathways were uncovered in the resolution of inflammatory exudates. These new families of local mediators control both the duration and magnitude of acute inflammation as well as the return of the site to homeostasis in the process of catabasis. This new genus of specialized proresolving mediators (SPM) includes essential fatty acid-derived lipoxins, resolvins, protectins, and, most recently, maresins. These families were named based on their unique structures and potent stereoselective actions. The temporally initiated biosynthesis of SPM and their direct impact on leukocyte trafficking and macrophage-directed clearance mechanisms provide clear evidence that resolution is an active, programmed response at the tissue level. Moreover, SPM that possess anti-inflammatory (ie, limiting PMN infiltration) and proresolving (enhance macrophage uptake and clearance of apoptotic PMN and microbial particles) actions as well as stimulating mucosal antimicrobial responses demonstrate that anti-inflammation and proresolution are different responses of the host and novel defining properties of these molecules. The mapping of new resolution circuits has opened the possibility for understanding mechanisms that lead from acute to chronic inflammation, or to the resolution thereof, as well as to potential, resolution-based immunopharmacological therapies.
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                Author and article information

                Contributors
                Role: Editor
                Journal
                PLoS One
                PLoS ONE
                plos
                plosone
                PLoS ONE
                Public Library of Science (San Francisco, USA )
                1932-6203
                2014
                5 August 2014
                : 9
                : 8
                Affiliations
                [1 ]Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong
                [2 ]School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
                National Eye Institute, United States of America
                Author notes

                Competing Interests: The authors have declared that no competing interests exist.

                Conceived and designed the experiments: CPP SOC KOC. Performed the experiments: YJQ YWYY WYL YPY KPC JLR. Analyzed the data: YJQ YWYY WYL. Contributed reagents/materials/analysis tools: WYL YPY KPC. Wrote the paper: YJQ CPP SOC KOC.

                Article
                PONE-D-14-02072
                10.1371/journal.pone.0103995
                4122397
                25093862

                This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

                Page count
                Pages: 12
                Funding
                This work was supported in part by a block grant of the University Grants Committee Hong Kong, a GRF Grant (Project No. CUHK461612), a seed grant from Lui Che Woo Institute of Innovative Medicine (Project No. 8303107) and the Endowment Fund for Lim Por-Yen Eye Genetics Research Centre, Hong Kong. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
                Categories
                Research Article
                Biology and Life Sciences
                Immunology
                Immune Response
                Inflammation
                Medicine and Health Sciences
                Physical Sciences
                Chemistry
                Phytochemistry
                Research and Analysis Methods
                Model Organisms
                Animal Models

                Uncategorized

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