title: Phenylbutyrate induces cathelicidin expression via the vitamin D receptor: Linkage to inflammatory and growth factor cytokines pathways.
abstract: Antimicrobial peptides (AMPs) constitute an indispensable arm of innate immunity against infectious microbes in humans. Induction of endogenous AMPs may become an alternative therapy against infections. Our previous studies have demonstrated phenylbutyrate (PBA) as a novel inducer of the AMPs cathelicidin (encoded by the CAMP gene) and human beta-defensin-1 in the human bronchial epithelial cell line VA10. In this work, we have continued by studying molecular mechanisms of PBA mediated induction of LL-37 expression and associated pathways in the human bronchial epithelial cell line VA10. In this study we demonstrate vitamin D receptor (VDR) as a key transcription factor required for PBA mediated up-regulation of the CAMP gene expression. PBA also increases mRNA expression of the vitamin D3 regulated genes CYP24A1 and CD14. The siRNA knockdown of VDR reduced PBA mediated increase in CAMP, CYP24A1 and CD14 expression. Furthermore, we demonstrate that PBA enhances Toll-Like Receptor 5 ligand flagellin regulated mRNA expression of the inflammatory cytokine TNFα and chemokine CXCL8. PBA also up-regulates the expression of the genes encoding the growth factor cytokines transforming growth factor (TGF) α, TGFβ1 and TGFβ2. Our results indicate that TGFβ type I receptor and epidermal growth factor receptor are involved in PBA mediated CAMP regulation. Finally, we show that co-treatment with PBA and vitamin D3 reduces Pseudomonas aeruginosa growth in vitro.
authors.affiliation: Biomedical Center and Department of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
authors.forename: Nikhil N
authors.initials: NN
authors.lastname: Kulkarni
authors.forename: Zhiqian
authors.initials: Z
authors.lastname: Yi
authors.forename: Carolin
authors.initials: C
authors.lastname: Huehnken
authors.forename: Birgitta
authors.initials: B
authors.lastname: Agerberth
authors.forename: Gudmundur H
authors.initials: GH
authors.lastname: Gudmundsson
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D002762:Cholecalciferol / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism*; D005408:Flagellin / Q000378:metabolism; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000473:pathology*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008024:Ligands; D008826:Microbial Sensitivity Tests; D010654:Phenylbutyrates / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D051198:Toll-Like Receptor 5 / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D065668:Vitamin D3 24-Hydroxylase / Q000235:genetics / Q000378:metabolism; D023083:beta-Defensins / Q000235:genetics / Q000378:metabolism; D054804:Cathelicidins
chemical_list: D023181:Antimicrobial Cationic Peptides; D016207:Cytokines; C406407:DEFB1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D010654:Phenylbutyrates; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D051198:Toll-Like Receptor 5; D023083:beta-Defensins; D005408:Flagellin; D002762:Cholecalciferol; C075773:4-phenylbutyric acid; D065668:Vitamin D3 24-Hydroxylase; D054804:Cathelicidins