Under normal steady state conditions, dying cells are removed by the immune system and an active immune response against cellular constituents is prevented. On the other hand, if dying cells are not efficiently removed, they may provoke autoimmunity. A large number of factors determine the outcome of the dying cell / phagocyte interaction. Amongst these factors are the efficiency of opsonization of apoptotic cells by serum components, especially early components of the classical complement (CCC) pathway; active immunosuppression of the phagocyte, the state of maturation of dendritic cells (DCs) and the cytokines in the milieu. In the first Aim, using purified components and component deficient serum, we will test the hypothesis that CCC are the dominant ligands responsible for immunosuppression of antigen presenting cells (ARC) that have ingested opsonized apoptotic cells. We will also determine how C-reactive protein (CRP) exerts its immunosuppressive effect on ARC and whether the suppressive effects exerted by these pathways can attenuate inflammatory properties of SLE blood cells. Using a defined T cell transgenic system and pseudo self antigen, the second Aim will determine how ingestion of apoptotic cells tolerize CD4+ T cells under steady state conditions. Having discovered novel alterations in DC populations that have ingested apoptotic cells, we will investigate whether suppressive changes fail to be initiated in lupus models that are accelerated by DCs that have ingested apoptotic cells. We have previously shown that maturation of DCs breaks tolerance to intracellular antigens but does not induce clinical disease in normal mice. In the third Aim we will determine what additional factors are required to produce pathogenic autoantibodies. Specifically the roles of type 1 interferons and regulatory T cells will be examined. Successful completion of these specific aims will lead to improved understanding of the mechanisms responsible for low complement and low CRP leading to SLE, for understanding how apoptotic cells attenuate T cell responses to self and will elucidate what specific immunological abnormalities need to be dysregulated in order to change what is normally a tolerizing signal in the immune system into a potent source of self antigen for autoimmunization. ? ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR048796-07
Application #
7270072
Study Section
Special Emphasis Panel (ZRG1-HAI-K (08))
Program Officer
Mancini, Marie
Project Start
2001-09-28
Project End
2011-07-31
Budget Start
2007-08-01
Budget End
2008-07-31
Support Year
7
Fiscal Year
2007
Total Cost
$299,922
Indirect Cost
Name
University of Washington
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
Buechler, Matthew B; Teal, Thomas H; Elkon, Keith B et al. (2013) Cutting edge: Type I IFN drives emergency myelopoiesis and peripheral myeloid expansion during chronic TLR7 signaling. J Immunol 190:886-91
Giltiay, Natalia V; Chappell, Craig P; Sun, Xizhang et al. (2013) Overexpression of TLR7 promotes cell-intrinsic expansion and autoantibody production by transitional T1 B cells. J Exp Med 210:2773-89
Elkon, Keith B; Wiedeman, Alice (2012) Type I IFN system in the development and manifestations of SLE. Curr Opin Rheumatol 24:499-505
Santer, Deanna M; Wiedeman, Alice E; Teal, Thomas H et al. (2012) Plasmacytoid dendritic cells and C1q differentially regulate inflammatory gene induction by lupus immune complexes. J Immunol 188:902-15
Elkon, Keith B; Silverman, Gregg J (2012) Naturally occurring autoantibodies to apoptotic cells. Adv Exp Med Biol 750:14-26
Elkon, Keith B; Santer, Deanna M (2012) Complement, interferon and lupus. Curr Opin Immunol 24:665-70
Gall, Alevtina; Treuting, Piper; Elkon, Keith B et al. (2012) Autoimmunity initiates in nonhematopoietic cells and progresses via lymphocytes in an interferon-dependent autoimmune disease. Immunity 36:120-31
Peng, YuFeng; Elkon, Keith B (2011) Autoimmunity in MFG-E8-deficient mice is associated with altered trafficking and enhanced cross-presentation of apoptotic cell antigens. J Clin Invest 121:2221-41
Elkon, Keith B; Stone, Vivian V (2011) Type I interferon and systemic lupus erythematosus. J Interferon Cytokine Res 31:803-12
Santer, Deanna M; Hall, Brian E; George, Thaddeus C et al. (2010) C1q deficiency leads to the defective suppression of IFN-alpha in response to nucleoprotein containing immune complexes. J Immunol 185:4738-49

Showing the most recent 10 out of 20 publications