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RELMα-expressing macrophages protect against fatal lung damage and reduce parasite burden during helminth infection

Branislav Krljanac1, Christoph Schubart1, Ronald Naumann2

  • 1Department of Infection Biology, University Hospital Erlangen and Friedrich-Alexander University Erlangen-Nuremberg (FAU), 91054 Erlangen, Germany.

Science Immunology
|May 26, 2019
PubMed

Insights

Alternatively activated macrophages (AAMs) expressing resistin-like molecule alpha (RELMα) are crucial for resolving lung inflammation and protecting against helminth infections. These macrophages are essential for preventing fatal lung damage during primary and secondary infections.

Area of Science:

  • Immunology
  • Cell Biology
  • Parasitology

Background:

  • Alternatively activated macrophages (AAMs) play roles in tissue repair and immunity but their differentiation and function are not fully understood.
  • Murine AAMs express resistin-like molecule alpha (RELMα), a protein with significant immunomodulatory functions.

Purpose of the Study:

  • To visualize RELMα-expressing macrophages (MΦs) in vivo.
  • To investigate the role of RELMα+ MΦs in host defense against helminth infections.

Main Methods:

  • Generation of RELMα reporter/deleter mice.
  • Induction of helminth infection (Nippostrongylus brasiliensis).
  • Analysis of macrophage populations and function in vivo.

Main Results:

  • Helminth infection induced STAT6-dependent expansion of RELMα+ lung interstitial MΦs, but not alveolar MΦs.
  • RELMα+ MΦs were essential for preventing fatal lung damage during primary infection.
  • Specific deletion of RELMα+ MΦs abrogated protective immunity during secondary infection.

Conclusions:

  • RELMα reporter/deleter mice enable visualization and functional studies of AAMs.
  • RELMα+ MΦs exhibit tissue compartmentalization.
  • These macrophages are critical for resolving severe lung inflammation and conferring protection against migrating helminths.

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