Cited by 281interferon and immune responsesPneumonia and Respiratory InfectionsImmune Response and Inflammation

The DOI matches its Crossref record; 44 of the 44 references it cites were found in a registry or an index; none of the 12 sources its claims cite is checked for support yet.

Synergistic stimulation of type I interferons during influenza virus coinfection promotes Streptococcus pneumoniae colonization in mice

Open access
Nakamura, Shigeki, Davis, Kimberly M., Weiser, Jeffrey N.·2011·Journal of Clinical Investigation

Abstract

Pneumococcal infection of the respiratory tract is often secondary to recent influenza virus infection and accounts for much of the morbidity and mortality during seasonal and pandemic influenza. Here, we show that coinfection of the upper respiratory tract of mice with influenza virus and pneumococcus leads to synergistic stimulation of type I IFNs and that this impairs the recruitment of macrophages, which are required for pneumococcal clearance, due to decreased production of the chemokine CCL2. Type I IFN expression was induced by pneumococcal colonization alone. Colonization followed by influenza coinfection led to a synergistic type I IFN response, resulting in increased density of colonizing bacteria and susceptibility to invasive infection. This enhanced type I IFN response inhibited production of the chemokine CCL2, which promotes the recruitment of macrophages and bacterial clearance. Stimulation of CCL2 by macrophages upon pneumococcal infection alone required the pattern recognition receptor Nod2 and expression of the pore-forming toxin pneumolysin. Indeed, the increased colonization associated with concurrent influenza virus infection was not observed in mice lacking Nod2 or the type I IFN receptor, or in mice challenged with pneumococci lacking pneumolysin. We therefore propose that the synergistic stimulation of type I IFN production during concurrent influenza virus and pneumococcal infection leads to increased bacterial colonization and suggest that this may contribute to the higher rates of disease associated with coinfection in humans.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

In a mouse upper respiratory tract coinfection model, influenza virus and pneumococcus synergistically induced type I IFNs, which suppressed CCL2-dependent macrophage recruitment and increased pneumococcal colonization. This type I IFN–dependent effect required Nod2 and pneumolysin pore formation and was associated with higher rates of invasive disease.

Key findings

  • Pneumococcal colonization alone induced a moderate type I IFN response, but additional type I IFN stimulation with intranasal poly-ICLC increased mean pneumococcal colonization density by greater than 20-fold at day 7; this effect was absent in *Ifnar*−/− mice.
  • Concurrent influenza PR8 infection after pneumococcal colonization caused synergistic IFN-β expression, inhibited macrophage but not neutrophil recruitment, decreased *Ccl2* but not KC expression, and increased pneumococcal load; none of these increases occurred in *Ifnar*−/− mice.
  • The increased colonization during coinfection required Nod2 and pneumolysin: *Nod2*−/− mice and mice challenged with pneumolysin mutants (*ply*− or *plyW433F*) did not show synergistic IFN-β induction or increased colonization density.
  • Coinfection with an invasive serotype 6A pneumococcal strain led to a higher rate of late-onset sepsis compared with pneumococcal challenge alone.

Methods

  • Mice were colonized intranasally with *S. pneumoniae* strain P1121 (type 23F; ~10^7 CFU) and then infected intranasally with influenza A virus PR8 (1,000 TCID50) one day later; some experiments used poly-ICLC, invasive serotype 6A strain P1547, or pneumolysin mutants.
  • Wild-type C57BL/6 and congenic *Nod2*−/−, *Tlr2*−/−, *Ccr2*−/−, and *Ifnar*−/− mice were used, with additional *Irf3*−/− and *Irf5*−/− bone marrow–derived macrophages; outcomes included URT lavage quantitative culture, qRT-PCR for IFN-α/β, *Ccl2*, KC, and IL-17A, flow cytometry for macrophages/neutrophils, ELISA for CCL2, and luciferase NF-κB reporter assays.
  • Statistical comparisons used ANOVA with Dunn’s post-tests, with survival compared by Fisher’s exact test; P < 0.05 was considered significant.

Limitations

  • Stated: the components downstream of Nod2 affected by the type I IFN response to *S. pneumoniae* were not yet defined, and how the Nod2-dependent pathway synergizes with the influenza-stimulated pathway remains to be understood.
  • Stated: the effect of influenza virus on pneumococcal colonization may be most relevant to concurrent infection; when P1121 was given on day 6 after PR8, there was no synergistic type I IFN stimulation or significant effect on colonization density at day 7.
  • Evident: the study is a mouse model of URT coinfection, and the authors note that their model avoided direct LRT inoculation and showed minimal lung viral/bacterial titers and pathology, so the findings may not fully represent secondary pneumococcal pneumonia or human coinfection.

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Integrity signals

Registry

Crossref · 10.1172/jci57762

Cites

44 of 44 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 12 cited sources checked · 0 supported · 0 flagged

Show all 48 claims

  • It may state two separate claims as one. 10
  • Probably not a substantial claim. 5
14 of 14
  • The paper relies on this without support.

    The mouse model of upper respiratory tract coinfection is representative of human coinfection.

    “and suggest that this may contribute to the higher rates of disease associated with coinfection in humans.”
    “our report offers a mechanistic explanation for the association of acute viral infections and the increased rates of pneumococcal disease and its markedly seasonal pattern (5,20).”
  • The paper relies on this without support.

    Colonization precedes pneumonia.

    “Since colonization precedes pneumonia, both mechanisms -increased bacterial load in the URT and compromised innate immunity in the LRT -could contribute to the high rates of disease during coinfection.”
  • The paper relies on this without support.

    The type I IFN response is common to many viruses.

    “Since the IFN response is common to many viruses, our report offers a mechanistic explanation for the association of acute viral infections and the increased rates of pneumococcal disease and its markedly seasonal pattern (5,20).”
  • The paper relies on this without support.

    Poly-ICLC is a synthetic analog of viral dsRNA.

    “Polyinosinic-polycytidylic acid condensed with poly-l-lysine (poly-ICLC, Hiltonol), a synthetic analog of viral dsRNA, was supplied by Oncovir Inc.”
4 of 4

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  1. Zhang, 2009, J Clin Invest., 119, 1899

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Metadata

Authors
Nakamura, S., Davis, K. M., & Weiser, J. N.
Affiliations
University of Pennsylvania (US)
Corresponding author
Weiser, Jeffrey N.
Venue
Journal of Clinical Investigation
Published
2011-09-01
Volume
121
Issue
9
Pages
3657-3665
ISSN
0021-9738 (ISSN-L)
OpenAlex
W2032969319
Cited by
280
References
44
Citations by year
2026: 11 · 2025: 7 · 2024: 17 · 2023: 11 · 2022: 17 · 2021: 21 · 2020: 20 · 2019: 18 · 2018: 27 · 2017: 16 · 2016: 20 · 2015: 19 · 2014: 31 · 2013: 22 · 2012: 22
FWCI
10.79
Type
journal article
Language
en
Open access
Locations
  • Journal of Clinical Investigation (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • U.S. Public Health Service
  • National Institute of Allergy and Infectious Diseases (R01AI038446, U19AI083022, AI 38446, R21AI044231, R01AI044231, T32AI060516, AI44231, R37AI038446)
Topics
  • Life Sciences › Immunology and Microbiology › Immunology › interferon and immune responses
  • Health Sciences › Medicine › Epidemiology › Pneumonia and Respiratory Infections
  • Life Sciences › Immunology and Microbiology › Immunology › Immune Response and Inflammation
Keywords
influenza virus, Streptococcus pneumoniae, co-infection, type I interferon, MCP-1, macrophage recruitment, pneumococcal carriage, NOD2, pneumolysin, secondary bacterial infection, invasive pneumococcal disease, chemokines, innate immunity
MeSH terms
Animals, Cells, Cultured, Female, Interferon Type I, Macrophages, Male, Mice, Inbred C57BL, Orthomyxoviridae, Orthomyxoviridae Infections, Pneumococcal Infections, Streptococcus pneumoniae, Trachea, Mice, Knockout, Chemokine CCL2, Mice, Nod2 Signaling Adaptor Protein

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