Respiratory syncytial virus infection augments NOD2 signaling in an IFN-β-dependent manner in human primary cells.
Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants, with remarkable variability in disease severity. An exaggerated proinflammatory response and influx of leukocytes is part of the pathogenesis of severe RSV disease. Here, we show an increase in proinflammatory cytokine production by human immune cells after stimulation with RSV and muramyl dipeptide (MDP), which is recognized by nucleotide-binding oligomerization domain containing 2 (NOD2). PBMCs from Crohn's disease patients homozygous for the 3020insC mutation in the NOD2 gene did not show a synergistic response to stimulation with RSV and MDP, suggesting that NOD2 is essential for the observed synergy. Further experiments aimed at identifying the viral ligand indicated that viral RNA plays an essential role in the recognition of RSV. Stimulation with RSV or Poly(I:C) induced IFN-β expression, which resulted in an increased expression of the viral receptors TLR3 and RIG-I, as well as an increased NOD2 expression. Our data indicate that IFN-β induction by viral RNA is an essential first step in the increased proinflammatory response to MDP. We hypothesize that the enhanced proinflammatory response to MDP following RSV infection may be an important factor in determining the outcome of the severity of disease.
Department of Pediatrics, Radboud University Medical Centre, Nijmegen, Netherlands.
Marloes
M
Vissers
Thijs
T
Remijn
Marije
M
Oosting
Dirk J
DJ
de Jong
Dimitri A
DA
Diavatopoulos
Peter W M
PW
Hermans
Gerben
G
Ferwerda
D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000276:immunology; D002478:Cells, Cultured; D003424:Crohn Disease / Q000276:immunology*; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018836:Inflammation Mediators / Q000378:metabolism; D016899:Interferon-beta / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D053473:Nod2 Signaling Adaptor Protein / Q000235:genetics / Q000378:metabolism*; D061251:Primary Cell Culture; D012367:RNA, Viral / Q000378:metabolism*; D011971:Receptors, Immunologic; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology*; D012136:Respiratory Syncytial Viruses / Q000502:physiology*; D015398:Signal Transduction; D051196:Toll-Like Receptor 3 / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
D018836:Inflammation Mediators; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein; D012367:RNA, Viral; D011971:Receptors, Immunologic; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; D000119:Acetylmuramyl-Alanyl-Isoglutamine; D016899:Interferon-beta; C452820:RIGI protein, human; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases