title: Neutrophils contribute to excess serum BAFF levels and promote CD4+ T cell and B cell responses in lupus-prone mice.
abstract: Despite increased frequencies of neutrophils found in autoimmune diseases such as systemic lupus erythematosus (SLE), how they contribute to disease pathogenesis and the mechanisms that affect the accumulation of neutrophils are poorly understood. The aim of this study was to identify factors in autoantibody-mediated autoimmunity that controls the accumulation of spleen resident neutrophils and to determine whether neutrophils contribute to abnormal B cell responses. Increased levels of the cytokine BAFF have been linked to loss of B cell tolerance in autoimmunity, but the cellular source responsible for excess BAFF is unknown. B cell maturation antigen (BCMA) is a receptor for BAFF and is critical for the survival of bone marrow plasma cells. Paradoxically, BCMA deficiency exacerbates the formation of autoantibody-secreting plasma cells in spleens of lupus-prone mice and the reasons for this effect are not understood. Here we analyzed the phenotype, localization and function of neutrophils in spleens of healthy mice and congenic lupus-prone mice, and compared mice sufficient or deficient in BCMA expression. Neutrophils were found to be significantly increased in frequency and activation status in spleens of lupus-prone mice when BCMA was absent. Furthermore, neutrophils localized within T cell zones and enhanced CD4(+) T cell proliferation and IFNγ production through the production of BAFF. Reduced BAFF and IFNγ serum levels, decreased frequencies of IFNγ-producing T cells, germinal center B cells, and autoantibody production after neutrophil depletion indicated the involvement of neutrophils in these autoimmune traits. Thus, we have identified a novel role for BCMA to control excess BAFF production in murine lupus through restraining the accumulation of BAFF-producing neutrophils. Our data suggests that devising therapeutic strategies to reduce neutrophils in autoimmunity may decrease BAFF levels and ameliorate disease.
authors.affiliation: Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America; Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Coquery
authors.affiliation: Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Nekeithia S
authors.initials: NS
authors.lastname: Wade
authors.affiliation: Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: William M
authors.initials: WM
authors.lastname: Loo
authors.affiliation: Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America; Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, United States of America; Center for Cell Clearance, University of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Kinchen
authors.affiliation: Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America; Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Cox
authors.affiliation: Division of Extramural Research, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Chao
authors.initials: C
authors.lastname: Jiang
authors.affiliation: Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, United States of America; Department of Pathology, University of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Tung
authors.affiliation: Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America; Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Loren D
authors.initials: LD
authors.lastname: Erickson
mesh_terms: D000818:Animals; D015551:Autoimmunity / Q000235:genetics / Q000276:immunology*; D053264:B-Cell Activating Factor / Q000276:immunology / Q000378:metabolism*; D053301:B-Cell Maturation Antigen / Q000276:immunology / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D051379:Mice; D009504:Neutrophils / Q000276:immunology / Q000473:pathology; D013154:Spleen / Q000276:immunology / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D053264:B-Cell Activating Factor; D053301:B-Cell Maturation Antigen; C505720:Tnfsf13b protein, mouse