Plasma gelsolin improves lung host defense against pneumonia by enhancing macrophage NOS3 function

Am J Physiol Lung Cell Mol Physiol. 2015 Jul 1;309(1):L11-6. doi: 10.1152/ajplung.00094.2015. Epub 2015 May 8.


Plasma gelsolin (pGSN) functions as part of the "extracellular actin-scavenging system," but its potential to improve host defense against infection has not been studied. In a mouse model of primary pneumococcal pneumonia, recombinant human pGSN (rhu-pGSN) caused enhanced bacterial clearance, reduced acute inflammation, and improved survival. In vitro, rhu-pGSN rapidly improved lung macrophage uptake and killing of bacteria (Streptococcus pneumoniae, Escherichia coli, and Francisella tularensis). pGSN triggers activating phosphorylation (Ser(1177)) of macrophage nitric oxide synthase type III (NOS3), an enzyme with important bactericidal functions in lung macrophages. rhu-pGSN failed to enhance bacterial killing by NOS3(-/-) macrophages in vitro or bacterial clearance in NOS3(-/-) mice in vivo. Prophylaxis with immunomodulators may be especially relevant for patients at risk for secondary bacterial pneumonia, e.g., after influenza. Treatment of mice with pGSN challenged with pneumococci on postinfluenza day 7 (the peak of enhanced susceptibility to secondary infection) caused a ∼15-fold improvement in bacterial clearance, reduced acute neutrophilic inflammation, and markedly improved survival, even without antibiotic therapy. pGSN is a potential immunomodulator for improving lung host defense against primary and secondary bacterial pneumonia.

Keywords: gelsolin; innate immunity; lung macrophages; nitric oxide; pneumonia.

Publication types

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

MeSH terms

  • Animals
  • Cell Line
  • Disease Models, Animal
  • Disease Susceptibility
  • Escherichia coli / immunology
  • Francisella tularensis / immunology
  • Gelsolin / blood
  • Gelsolin / pharmacology*
  • Inflammation / drug therapy
  • Inflammation / immunology
  • Influenza A Virus, H1N1 Subtype / immunology
  • Lung / microbiology*
  • Macrophages, Alveolar / enzymology
  • Macrophages, Alveolar / immunology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Nitric Oxide Synthase Type III / genetics
  • Nitric Oxide Synthase Type III / immunology*
  • Orthomyxoviridae Infections / immunology
  • Phagocytosis / immunology
  • Pneumonia, Pneumococcal / immunology*
  • Pneumonia, Pneumococcal / mortality
  • Pneumonia, Pneumococcal / prevention & control
  • Recombinant Proteins / pharmacology
  • Streptococcus pneumoniae / immunology


  • Gelsolin
  • Recombinant Proteins
  • Nitric Oxide Synthase Type III
  • Nos3 protein, mouse