The common γ-chain cytokine IL-7 promotes immunopathogenesis during fungal asthma

Mucosal Immunol. 2018 Sep;11(5):1352-1362. doi: 10.1038/s41385-018-0028-1. Epub 2018 Jun 15.

Abstract

Asthmatics sensitized to fungi are reported to have more severe asthma, yet the immunopathogenic pathways contributing to this severity have not been identified. In a pilot assessment of human asthmatics, those subjects sensitized to fungi demonstrated elevated levels of the common γ-chain cytokine IL-7 in lung lavage fluid, which negatively correlated with the lung function measurement PC20. Subsequently, we show that IL-7 administration during experimental fungal asthma worsened lung function and increased the levels of type 2 cytokines (IL-4, IL-5, IL-13), proallergic chemokines (CCL17, CCL22) and proinflammatory cytokines (IL-1α, IL-1β). Intriguingly, IL-7 administration also increased IL-22, which we have previously reported to drive immunopathogenic responses in experimental fungal asthma. Employing IL22CreR26ReYFP reporter mice, we identified γδ T cells, iNKT cells, CD4 T cells and ILC3s as sources of IL-22 during fungal asthma; however, only iNKT cells were significantly increased after IL-7 administration. IL-7-induced immunopathogenesis required both type 2 and IL-22 responses. Blockade of IL-7Rα in vivo resulted in attenuated IL-22 production, lower CCL22 levels, decreased iNKT cell, CD4 T-cell and eosinophil recruitment, yet paradoxically increased dynamic lung resistance. Collectively, these results suggest a complex role for IL-7 signaling in allergic fungal asthma.

Publication types

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

MeSH terms

  • Adult
  • Asthma / immunology*
  • Asthma / microbiology*
  • Bronchoalveolar Lavage Fluid / immunology
  • Bronchoalveolar Lavage Fluid / microbiology
  • CD4-Positive T-Lymphocytes / immunology
  • CD4-Positive T-Lymphocytes / microbiology
  • Chemokines / immunology
  • Cytokines / immunology
  • Female
  • Fungi / immunology*
  • Humans
  • Interleukin-7 / immunology*
  • Lung / immunology
  • Lung / microbiology
  • Male
  • Mycoses / immunology*
  • Pilot Projects

Substances

  • Chemokines
  • Cytokines
  • IL7 protein, human
  • Interleukin-7