title: Systems biology evaluation of immune responses induced by human host defence peptide LL-37 in mononuclear cells.
abstract: The immune system is very complex, it involves the integrated regulation and expression of hundreds of proteins. To understand in greater detail how the human host defence immunomodulatory peptide LL-37 interacts with innate immunity, a systems approach was pursued. Polychromatic flow cytometry was employed to demonstrate that within human peripheral blood mononuclear cells, CD14+ monocytes, myeloid and plasmocytoid dendritic cells and T- and B-lymphocytes, all responded to LL-37, with the differential production of intracellular cytokines. Microarray analyses with CD14+ monocytes indicated the differential expression of 475 genes in response to stimulation with LL-37. To understand this complex response, bioinformatic interrogation, using InnateDB, of the gene ontology, signalling pathways and transcription factor binding sites was undertaken. Activation of the IkappaBalpha/NFkappaB, mitogen-activated protein kinases p38, ERK1/2 and JNK, and PI3K signalling pathways in response to LL-37 was demonstrated by pathway and ontology over-representation analyses, and confirmed experimentally by inhibitor studies. Computational analysis of the predicted transcription factor binding sites upstream of the genes that were regulated by LL-37 predicted the involvement of several transcription factors including NFkappaB and five novel factors, AP-1, AP-2, SP-1, E2F1, and EGR, which were experimentally confirmed to respond to LL-37 by performing transcription factor array studies on nuclear extracts from LL-37 treated mononuclear cells. These data are discussed as reflecting the integration of several responsive signalling pathways through the involvement of transcription factor complexes in gene expression activated by LL-37 in human mononuclear cells.
authors.affiliation: Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Neeloffer
authors.initials: N
authors.lastname: Mookherjee
authors.forename: Pamela
authors.initials: P
authors.lastname: Hamill
authors.forename: Jennifer
authors.initials: J
authors.lastname: Gardy
authors.forename: Darren
authors.initials: D
authors.lastname: Blimkie
authors.forename: Reza
authors.initials: R
authors.lastname: Falsafi
authors.forename: Avinash
authors.initials: A
authors.lastname: Chikatamarla
authors.forename: David J
authors.initials: DJ
authors.lastname: Arenillas
authors.forename: Silvana
authors.initials: S
authors.lastname: Doria
authors.forename: Tobias R
authors.initials: TR
authors.lastname: Kollmann
authors.forename: Robert E W
authors.initials: RE
authors.lastname: Hancock
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D001665:Binding Sites; D003713:Dendritic Cells / Q000378:metabolism; D020869:Gene Expression Profiling; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects*; D009000:Monocytes / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology*; D049490:Systems Biology / Q000379:methods*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D054804:Cathelicidins
chemical_list: D023181:Antimicrobial Cationic Peptides; D014157:Transcription Factors; D054804:Cathelicidins