CCR2 mediates increased susceptibility to post-H1N1 bacterial pneumonia by limiting dendritic cell induction of IL-17

Mucosal Immunol. 2019 Mar;12(2):518-530. doi: 10.1038/s41385-018-0106-4. Epub 2018 Nov 29.

Abstract

Post influenza bacterial pneumonia is associated with significant mortality and morbidity. Dendritic cells (DCs) play a crucial role in host defense against bacterial pneumonia, but their contribution to post influenza-susceptibility to secondary bacterial pneumonia is incompletely understood. WT and CCR2-/- mice were infected with 100 plaque forming units (pfu) H1N1 intranasally alone or were challenged on day 5 with 7 × 107 colony forming units (cfu) methicillin-resistant Staphylococcus aureus intratracheally. WT mice express abundant CCL2 mRNA and protein post-H1N1 alone or dual infection. CCR2-/- mice had significantly higher survival as compared to WT mice, associated with significantly improved bacterial clearance at 24 and 48 h (10-fold and 14-fold, respectively) post bacterial challenge. There was robust upregulation of IL-23 and IL-17 as well as downregulation of IL-27 expression in CCR2-/- mice following sequential infection as compared to WT mice, which was also associated with significantly greater accumulation of CD103+ DC. Finally, WT mice treated with a CCR2 inhibitor showed improved bacterial clearance in association with similar cytokine profiles as CCR2-/- mice. Thus, CCR2 significantly contributes to increased susceptibility to bacterial infection after influenza pneumonia likely via altered dendritic cell responses and thus, CCR2 antagonism represents a potential therapeutic strategy.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antigens, CD / metabolism
  • Cells, Cultured
  • Dendritic Cells / immunology*
  • Disease Susceptibility
  • Humans
  • Influenza A Virus, H1N1 Subtype / physiology*
  • Influenza, Human / immunology*
  • Influenza, Human / therapy
  • Integrin alpha Chains / metabolism
  • Interleukin-17 / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Molecular Targeted Therapy
  • Neutrophils / immunology
  • Orthomyxoviridae Infections / immunology*
  • Orthomyxoviridae Infections / therapy
  • Pneumonia, Bacterial / immunology*
  • Pneumonia, Bacterial / therapy
  • Receptors, CCR2 / genetics
  • Receptors, CCR2 / metabolism*
  • Th17 Cells / physiology*

Substances

  • Antigens, CD
  • Ccr2 protein, mouse
  • Integrin alpha Chains
  • Interleukin-17
  • Receptors, CCR2
  • alpha E integrins