title: Differential regulation of inflammation by inflammatory mediators in cystic fibrosis lung epithelial cells.
abstract: Cystic fibrosis (CF) is due to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which cause a massively proinflammatory phenotype in the CF airway. The chemical basis of the inflammation is hyperproduction of interleukin-8 (IL-8) by CF airway epithelial cells, based on both an intrinsic mutation-dependent mechanism and by infection. In infection-free, cultured CF lung epithelial cells, high levels of the microRNA (miR), miR-155, is responsible for hyperexpression of IL-8. However, whether infection-induced IL-8 expression in CF cells is also mediated by miR-155 is not known. We have hypothesized that miR-155 might be a general mediator of enhanced IL-8 expression in CF cells, either in response to other cytokine/chemokine mediators of inflammation, or after exposure to infectious agents. Here we find that a reduction in miR-155 accompanies suppression of IL-8 by either the anti-inflammatory cytokine IL-10 or by inhibition of ambient IL-1β with a neutralizing antibody. However, attempts to elevate IL-8 levels with either intact bacteria [viz. a mucoid strain of Pseudomonas aeruginosa (PA)], or lipopolysaccharide were unable to elevate miR-155 above its intrinsically high level in the absence of these agents. Instead, in response to PA infection, the CF cells modestly suppress the expression of miR-155, and express a novel set of miRs, including miR-215. We find that ex vivo CF lung epithelial cells also express high levels of both miR-155 and miR-215. The predicted module of infection-induced mRNA targets focuses on activation of the NFκB-signaling pathway, and on the proapoptotic p53-signaling pathway. We interpret these data to suggest that that CF lung epithelial cells respond to PA or bacterial cell products with a novel miR program that may carry with it serious challenges to survival.
authors.affiliation: Molecular and Cell Biology Program, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Tsuchiya
authors.forename: Parameet
authors.initials: P
authors.lastname: Kumar
authors.forename: Sharmistha
authors.initials: S
authors.lastname: Bhattacharyya
authors.forename: Sangbrita
authors.initials: S
authors.lastname: Chattoraj
authors.forename: Meera
authors.initials: M
authors.lastname: Srivastava
authors.forename: Harvey B
authors.initials: HB
authors.lastname: Pollard
authors.forename: Roopa
authors.initials: R
authors.lastname: Biswas
mesh_terms: D002460:Cell Line; D003550:Cystic Fibrosis / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D007249:Inflammation / Q000276:immunology / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D018836:Inflammation Mediators / Q000276:immunology / Q000378:metabolism*; D016753:Interleukin-10 / Q000276:immunology / Q000378:metabolism; D053583:Interleukin-1beta / Q000276:immunology / Q000378:metabolism; D016209:Interleukin-8 / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D008168:Lung; D035683:MicroRNAs / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D011552:Pseudomonas Infections / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000276:immunology
chemical_list: C508606:CXCL8 protein, human; C508609:IL10 protein, human; C508585:IL1B protein, human; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D016209:Interleukin-8; C524942:MIRN155 microRNA, human; C553667:MIRN215 microRNA, human; D035683:MicroRNAs; D016753:Interleukin-10