title: TNFα Regulates SIRT1 Cleavage during Ocular Autoimmune Disease.
abstract: Elevated tumor necrosis factor (TNF) α levels are associated with chronic autoimmune diseases in which effects of TNFα on immune cells are multiple and complex. Analysis of uveitis in mice exhibiting severe autoimmune inflammation, resulting in a destructive subtotal loss of photoreceptors, revealed the presence of high plasma levels of TNFα and a significant population of CD4(+)TNFα(+) cells in the periphery and the eye at peak disease (TNFα(hi)). We have shown previously by pharmacological activation that the deacetylase Sirtuin 1 (SIRT1) has an anti-inflammatory role in a less severe, TNFα(lo) model of uveitis. We now show that SIRT1 activation fails to clinically suppress severe TNFα(hi) disease, whereas glucocorticoid treatment is successful. TNFα has been reported to mediate cleavage and inactivation of SIRT1 during inflammation, and at peak disease we observed both full-length and cleaved SIRT1 in draining lymph node cells. In vivo systemic TNFα blockade suppressed severe ocular disease and restricted SIRT1 cleavage in the periphery, maintaining full-length active SIRT1 protein. When combining a suboptimal TNFα blockade with SIRT1 activation, a synergistic suppression of severe disease compared with TNFα blockade alone occurred. Our data suggest a new role for TNFα in exacerbating the severity of autoimmune disease by regulating SIRT1 cleavage in draining lymph node effector cells. SIRT1 activation may be effective as an adjunctive treatment for inflammatory conditions not fully controlled by TNFα inhibitors.
authors.affiliation: Department of Genetics, University College London Institute of Ophthalmology, London, United Kingdom. Electronic address: p.gardner@ucl.ac.uk.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Gardner
authors.affiliation: Department of Genetics, University College London Institute of Ophthalmology, London, United Kingdom.
authors.forename: Samia
authors.initials: S
authors.lastname: Yazid
authors.affiliation: Department of Genetics, University College London Institute of Ophthalmology, London, United Kingdom; Academic Unit of Ophthalmology, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Chu
authors.affiliation: Academic Unit of Ophthalmology, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom; National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital and University College London Institute of Ophthalmology, London, United Kingdom.
authors.forename: David A
authors.initials: DA
authors.lastname: Copland
authors.affiliation: Ophthiris Discovery Performance Unit, GlaxoSmithKline Ophthalmology, Stevenage, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Adamson
authors.affiliation: Department of Genetics, University College London Institute of Ophthalmology, London, United Kingdom; Academic Unit of Ophthalmology, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom; National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital and University College London Institute of Ophthalmology, London, United Kingdom; School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Dick
authors.affiliation: National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital and University College London Institute of Ophthalmology, London, United Kingdom; Department of Ocular Biology and Therapeutics, University College London Institute of Ophthalmology, London, United Kingdom.
authors.forename: Virginia L
authors.initials: VL
authors.lastname: Calder
mesh_terms: D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D015153:Blotting, Western; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D005434:Flow Cytometry; D051379:Mice; D056564:Sirtuin 1 / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000378:metabolism*; D014605:Uveitis / Q000276:immunology / Q000378:metabolism* / Q000473:pathology
chemical_list: D014409:Tumor Necrosis Factor-alpha; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1