title: Neutrophils express distinct RNA receptors in a non-canonical way.
abstract: RNAs are capable of modulating immune responses by binding to specific receptors. Neutrophils represent the major fraction of circulating immune cells, but receptors and mechanisms by which neutrophils sense RNA are poorly defined. Here, we analyzed the mRNA and protein expression patterns and the subcellular localization of the RNA receptors RIG-I, MDA-5, TLR3, TLR7, and TLR8 in primary neutrophils and immortalized neutrophil-like differentiated HL-60 cells. Our results demonstrate that both neutrophils and differentiated HL-60 cells express RIG-I, MDA-5, and TLR8 at the mRNA and protein levels, whereas TLR3 and TLR7 are not expressed at the protein level. Subcellular fractionation, flow cytometry, confocal laser scanning microscopy, and immuno-transmission electron microscopy provided evidence that, besides the cytoplasm, RIG-I and MDA-5 are stored in secretory vesicles of neutrophils and showed that RIG-I and its ligand, 3p-RNA, co-localize at the cell surface without triggering neutrophil activation. In summary, this study demonstrates that neutrophils express a distinct pattern of RNA recognition receptors in a non-canonical way, which could have essential implications for future RNA-based therapeutics.
authors.affiliation: Department of Pediatric Surgery, Research Center, Dr von Hauner Children's Hospital, Ludwig Maximilians University of Munich, 80539 Munich, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Berger
authors.forename: Chin-Yuan
authors.initials: CY
authors.lastname: Hsieh
authors.forename: Martina
authors.initials: M
authors.lastname: Bakele
authors.forename: Veronica
authors.initials: V
authors.lastname: Marcos
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Rieber
authors.forename: Michael
authors.initials: M
authors.lastname: Kormann
authors.forename: Lauren
authors.initials: L
authors.lastname: Mays
authors.forename: Laura
authors.initials: L
authors.lastname: Hofer
authors.forename: Olaf
authors.initials: O
authors.lastname: Neth
authors.forename: Ljubomir
authors.initials: L
authors.lastname: Vitkov
authors.forename: Wolf Dietrich
authors.initials: WD
authors.lastname: Krautgartner
authors.forename: Dietrich
authors.initials: D
authors.lastname: von Schweinitz
authors.forename: Roland
authors.initials: R
authors.lastname: Kappler
authors.forename: Andreas
authors.initials: A
authors.lastname: Hector
authors.forename: Alexander
authors.initials: A
authors.lastname: Weber
authors.forename: Dominik
authors.initials: D
authors.lastname: Hartl
mesh_terms: D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D018922:HL-60 Cells; D006801:Humans; D000072640:Interferon-Induced Helicase, IFIH1; D008297:Male; D018375:Neutrophil Activation / Q000502:physiology*; D009504:Neutrophils; D012313:RNA; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism*; D022142:Secretory Vesicles / Q000235:genetics / Q000378:metabolism; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism*
chemical_list: C437968:PLAAT4 protein, human; D018168:Receptors, Retinoic Acid; D051193:Toll-Like Receptors; D012313:RNA; C452815:IFIH1 protein, human; D053487:DEAD-box RNA Helicases; D000072640:Interferon-Induced Helicase, IFIH1