A new protective role for S100A9 in regulation of neutrophil recruitment during invasive pneumococcal pneumonia.
The S100A8/A9 heterodimer is abundantly expressed by myeloid cells, especially neutrophils, but its mechanism of action is only partially determined. In this study we investigated S100A8/A9 involvement in the host response to Streptococcus pneumoniae infection making use of S100a9(-/-) mice that lack heterodimer expression in myeloid cells. S100a9(-/-) mice that were infected intranasally with pneumococci rapidly succumbed, with 80% mortality after 48 h, whereas the majority of wild-type mice recovered. Over this time period, S100a9(-/-) mice displayed an average 6-fold reduction in circulating and lung-recruited neutrophils. Taqman analysis of S100a9(-/-) lungs revealed decreased production of a dominant subset of 5 cytokines and chemokines associated with neutrophil recruitment. The greatest differential was with the cytokine granulocyte colony-stimulating factor (G-CSF) that causes bone marrow release of neutrophils into the circulation (1900-fold difference at 48 h). Treating S100a9(-/-) mice with G-CSF reversed their increased susceptibility to infection by enhancing both circulating neutrophils and neutrophil recruitment into infected lungs, by reducing pneumococcal colony forming units, and by elevation of chemokine CXCL1, cytokine IL-6, and endogenous G-CSF proteins. Thus S100A9, potentially with its partner S100A8, makes a major contribution in the host response to pneumococcal infection by increasing circulating neutrophils principally regulation of G-CSF production.
Leukocyte Adhesion Laboratory, Cancer Research United Kingdom London Research Institute, London, UK;
Katia
K
De Filippo
Institute of Infection and Global Health, University of Liverpool, Liverpool, UK; and Department of Infection, Immunity, and Inflammation, University of Leicester, Leicester, UK.
Daniel R
DR
Neill
Leukocyte Adhesion Laboratory, Cancer Research United Kingdom London Research Institute, London, UK;
Meg
M
Mathies
Institute of Infection and Global Health, University of Liverpool, Liverpool, UK; and Department of Infection, Immunity, and Inflammation, University of Leicester, Leicester, UK.
Mathieu
M
Bangert
Leukocyte Adhesion Laboratory, Cancer Research United Kingdom London Research Institute, London, UK;
Eileen
E
McNeill
Institute of Infection and Global Health, University of Liverpool, Liverpool, UK; and Department of Infection, Immunity, and Inflammation, University of Leicester, Leicester, UK.
Aras
A
Kadioglu
Leukocyte Adhesion Laboratory, Cancer Research United Kingdom London Research Institute, London, UK; nancy.hogg@cancer.org.uk.
Nancy
N
Hogg
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D040501:Calgranulin A / Q000502:physiology; D040502:Calgranulin B / Q000235:genetics / Q000502:physiology*; D019281:Dimerization; D004198:Disease Susceptibility; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology / Q000627:therapeutic use; D008168:Lung / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D008264:Macrophages / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009000:Monocytes / Q000276:immunology; D020556:Neutrophil Infiltration / Q000502:physiology*; D011018:Pneumonia, Pneumococcal / Q000276:immunology* / Q000382:microbiology; D013296:Streptococcus pneumoniae / Q000276:immunology / Q000302:isolation & purification
D040501:Calgranulin A; D040502:Calgranulin B; C576329:S100A9 protein, mouse; C086145:S100a8 protein, mouse; D016179:Granulocyte Colony-Stimulating Factor
G-CSF; Streptococcus pneumoniae; leukocytes