title: The murine Pbx1-d lupus susceptibility allele accelerates mesenchymal stem cell differentiation and impairs their immunosuppressive function.
abstract: Pre–B cell leukemia homeobox 1 (Pbx1)-d is a dominant-negative splice isoform of the gene Pbx1 that corresponds to the NZM2410 lupus susceptibility locus Sle1a1. Pbx1 is required to maintain stem cell self-renewal, including that of mesenchymal stem cells (MSCs). MSCs have immunosuppressive functions that require stem cell maintenance. We tested the hypothesis that the expression of Pbx1-d favors MSC differentiation and impairs their immunosuppressive functions. We demonstrate that Sle1a1 MSCs express high levels of Pbx1-d as compared with congenic C57BL/6J (B6) MSCs. Sle1a1 MSCs grew faster and differentiated significantly more rapidly into osteoblasts than did B6 MSCs. This corresponded to a significant decrease in the expression of genes associated with stemness and an increase in the expression of genes associated with differentiation. Additionally, Sle1a1 MSCs express a gene expression profile associated with an enhanced innate immunity and inflammation. Suppression of Ig production from TLR-activated B6 B cells and IL-2 secretion from activated B6 CD4+ T cells was significantly impaired in Sle1a1 MSCs as compared with B6 MSCs. B6.Sle1a1 MSCs showed intermediate activity in suppressing lupus immunophenotypes in three different mouse models. Taken together, these data suggest that the expression of the lupus susceptibility allele Pbx1-d isoform impairs MSC functions, which may contribute to lupus pathogenesis both through a defective immunosuppression and the promotion of a proinflammatory environment.
authors.affiliation: Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610
authors.forename: Shun
authors.initials: S
authors.lastname: Lu
authors.affiliation: Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610
authors.forename: Leilani
authors.initials: L
authors.lastname: Zeumer
authors.affiliation: Department of Periodontology, Department of Oral Biology, University of Florida, Gainesville, FL 32610
authors.forename: Heather
authors.initials: H
authors.lastname: Sorensen
authors.affiliation: Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610
authors.forename: Yunfai
authors.initials: Y
authors.lastname: Ng
authors.affiliation: Bioinformatic Core, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32610
authors.forename: Fahong
authors.initials: F
authors.lastname: Yu
authors.affiliation: Bioinformatic Core, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32610
authors.forename: Alberto
authors.initials: A
authors.lastname: Riva
authors.affiliation: Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610
authors.forename: Byron
authors.initials: B
authors.lastname: Croker
authors.affiliation: Department of Periodontology, Department of Oral Biology, University of Florida, Gainesville, FL 32610
authors.forename: Shannon
authors.initials: S
authors.lastname: Wallet
authors.affiliation: Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610
authors.forename: Laurence
authors.initials: L
authors.lastname: Morel
mesh_terms: D000818:Animals; D015551:Autoimmunity / Q000235:genetics / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation / Q000235:genetics*; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics*; D007108:Immune Tolerance / Q000276:immunology*; D007136:Immunoglobulins / Q000096:biosynthesis; D007156:Immunologic Memory / Q000276:immunology; D007249:Inflammation / Q000276:immunology; D007376:Interleukin-2 / Q000378:metabolism; D008180:Lupus Erythematosus, Systemic / Q000235:genetics / Q000473:pathology; D008213:Lymphocyte Activation / Q000276:immunology; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000166:cytology*; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D020033:Protein Isoforms / Q000235:genetics; D051193:Toll-Like Receptors / Q000276:immunology; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D018398:Homeodomain Proteins; D007136:Immunoglobulins; D007376:Interleukin-2; C481797:Pbx1 protein, mouse; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D020033:Protein Isoforms; D051193:Toll-Like Receptors; D014157:Transcription Factors