Respiratory syncytial virus infection augments NOD2 signaling in an IFN‐β‐dependent manner in human primary cells

Abstract

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.

Bacterial Lipopolysaccharide Inhibits Influenza Virus Infection of Human Macrophages and the Consequent Induction of CD8+ T Cell Immunity

“…Where relevant, PR8/34 was purified by rate zonal sedimentation on 25-80% w/v sucrose gradients as described [15]. Green fluorescent protein (GFP)-labeled RSV A2 (rgRSV30) [16] was cultured on HeLa cells as described previously [17]. Virus concentration was determined by titration on HeLa cells.…”

Muramyl dipeptide responsive pathways in Crohn’s disease: from NOD2 and beyond

“…Additionally, recent studies have revealed a synergistic proinflammatory cytokine response in human PBMCs stimulated with RSV followed by MDP stimulation. Interestingly, this synergic response is absent in PBMCs isolated from CD patients homozygous for the 3020insC mutation in the NOD2 gene [133]. These results suggest a critical role of NOD2 in this synergy and add an interesting aspect in how the loss of function mutations in NOD2 can eliminate essential immune responses.…”

An <em>In vitro</em> Model to Study Immune Responses of Human Peripheral Blood Mononuclear Cells to Human Respiratory Syncytial Virus Infection

“…In a previous study we showed that this model system can very easily be adapted to study inflammatory pathways induced by other viruses, e.g. influenza or rhinovirus 7 .…”

“…Therefore, as an addition to the cell lines and animal models currently used, we propose to use human primary PBMCs as a model for stimulation with HRSV. Human PBMCs can be obtained from a range of individuals to address specific research questions, including young children 6 , immunocompromised individuals as well as healthy adults 7 or elderly individuals 8 . PBMCs can be used to study innate aspects of infection as well as the adaptive response to the virus.…”