title: TLR7 drives accumulation of ABCs and autoantibody production in autoimmune-prone mice.
abstract: Although autoantibodies are the hallmarks of most autoimmune diseases, the mechanisms by which autoreactive B cells are generated and accumulate are still poorly understood. Overexpression of Toll-like receptor 7 (TLR7) that recognizes single-stranded RNAs has been implicated in systemic lupus erythematosus (SLE), although the cellular mechanism by which this receptor drives the disease is unknown. We recently identified a population of CD11c(+) age-associated B cells (ABCs) which is driven by TLR7 signaling, secretes autoantibodies and appears in autoimmune-prone mice by the time of onset of autoimmunity. Mice lacking the Mer receptor develop autoantibodies and splenomegaly similar to other mouse models of SLE. Here, we show that Mer(-/-) mice that lack TLR7 fail to develop anti-chromatin IgG antibodies, perhaps because they also fail to develop ABCs. Moreover, depletion of CD11c(+) ABCs from Mer(-/-) mice leads to rapid reduction in autoantibodies. Together, these data strongly suggest that ABCs and/or their descendants are the primary source of autoantibodies in Mer(-/-) mice and that TLR7 signaling is crucial for accumulation of ABCs and development of autoantibodies. These data demonstrate for the first time that TLR7, and not TLR9, is responsible for generation of anti-chromatin IgG antibodies in Mer(-/-) mice.
authors.affiliation: Integrated Department of Immunology, Howard Hughes Medical Institute, University of Colorado School of Medicine, Denver, CO 80206, USA. rubtsova@njhealth.org
authors.forename: Anatoly V
authors.initials: AV
authors.lastname: Rubtsov
authors.forename: Kira
authors.initials: K
authors.lastname: Rubtsova
authors.forename: John W
authors.initials: JW
authors.lastname: Kappler
authors.forename: Philippa
authors.initials: P
authors.lastname: Marrack
mesh_terms: D000818:Animals; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics; D001323:Autoantibodies / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D039521:CD11c Antigen / Q000235:genetics; D004167:Diphtheria Toxin / Q000494:pharmacology; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics; D066257:Heparin-binding EGF-like Growth Factor; D007074:Immunoglobulin G / Q000097:blood; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D008297:Male; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008822:Mice, Transgenic; D011971:Receptors, Immunologic / Q000172:deficiency / Q000235:genetics; D020825:T-Box Domain Proteins / Q000276:immunology; D051199:Toll-Like Receptor 7 / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D000098815:T-bet Transcription Factor
chemical_list: D000944:Antigens, Differentiation, B-Lymphocyte; D001323:Autoantibodies; D039521:CD11c Antigen; D004167:Diphtheria Toxin; C587884:Hbegf protein, mouse; D066257:Heparin-binding EGF-like Growth Factor; D007074:Immunoglobulin G; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; D020825:T-Box Domain Proteins; D000098815:T-bet Transcription Factor; C477038:Tlr7 protein, mouse; D051199:Toll-Like Receptor 7; C056705:mouse erythrocyte receptor; D049452:Green Fluorescent Proteins