title: Patterns of Transcriptional Response to 1,25-Dihydroxyvitamin D3 and Bacterial Lipopolysaccharide in Primary Human Monocytes.
abstract: The active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25D), plays an important immunomodulatory role, regulating transcription of genes in the innate and adaptive immune system. The present study examines patterns of transcriptome-wide response to 1,25D, and the bacterial lipopolysaccharide (LPS) in primary human monocytes, to elucidate pathways underlying the effects of 1,25D on the immune system. Monocytes obtained from healthy individuals of African-American and European-American ancestry were treated with 1,25D, LPS, or both, simultaneously. The addition of 1,25D during stimulation with LPS induced significant upregulation of genes in the antimicrobial and autophagy pathways, and downregulation of proinflammatory response genes compared to LPS treatment alone. A joint Bayesian analysis enabled clustering of genes into patterns of shared transcriptional response across treatments. The biological pathways enriched within these expression patterns highlighted several mechanisms through which 1,25D could exert its immunomodulatory role. Pathways such as mTOR signaling, EIF2 signaling, IL-8 signaling, and Tec Kinase signaling were enriched among genes with opposite transcriptional responses to 1,25D and LPS, respectively, highlighting the important roles of these pathways in mediating the immunomodulatory activity of 1,25D. Furthermore, a subset of genes with evidence of interethnic differences in transcriptional response was also identified, suggesting that in addition to the well-established interethnic variation in circulating levels of vitamin D, the intensity of transcriptional response to 1,25D and LPS also varies between ethnic groups. We propose that dysregulation of the pathways identified in this study could contribute to immune-mediated disease risk.
authors.affiliation: Department of Human Genetics, University of Chicago, Illinois 60637.
authors.forename: Silvia N
authors.initials: SN
authors.lastname: Kariuki
authors.affiliation: Department of Human Genetics, University of Chicago, Illinois 60637.
authors.forename: John D
authors.initials: JD
authors.lastname: Blischak
authors.affiliation: Department of Human Genetics, University of Chicago, Illinois 60637.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Nakagome
authors.affiliation: Department of Human Genetics, University of Chicago, Illinois 60637.
authors.forename: David B
authors.initials: DB
authors.lastname: Witonsky
authors.affiliation: Department of Human Genetics, University of Chicago, Illinois 60637 dirienzo@bsd.uchicago.edu.
authors.forename: Anna
authors.initials: A
authors.lastname: Di Rienzo
mesh_terms: D001499:Bayes Theorem; D001665:Binding Sites; D016000:Cluster Analysis; D019295:Computational Biology / Q000379:methods; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology*; D009000:Monocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism*; D059372:Nucleotide Motifs; D011485:Protein Binding; D018167:Receptors, Calcitriol / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic / Q000187:drug effects*; D059467:Transcriptome; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D008070:Lipopolysaccharides; D018167:Receptors, Calcitriol; C579457:VDR protein, human; C118756:dihydroxy-vitamin D3; D014807:Vitamin D
keywords: differential expression profiling; innate immune cells; pathway analysis; proinflammatory response