Inflammatory lung secretions inhibit dendritic cell maturation and function via neutrophil elastase.
BACKGROUND
Continuous episodes of infection are a feature of lung diseases such as chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF). Lung antigen-presenting dendritic cells (DCs) sample inhaled antigen to initiate immune responses. Therefore, we hypothesized that inflammatory mediators, such as neutrophil elastase (NE) released into the lung, may be able to modulate their activity.


OBJECTIVE
To determine whether sputum (from patients with COPD and those with CF) or NE can alter DC phenotype and function.


METHODS
NE and sputum samples were incubated with immature or mature murine DCs (mDCs). DC phenotype and function were studied by fluorescence-activated cell sorter and Western Blot analysis, assessing their expression of costimulatory molecules and their ability to induce T cell proliferation.


RESULTS
COPD/CF sputum samples and human NE downregulated the expression of CD40, CD80, and CD86 (but not major histocompatibility complex II) on DCs and inhibited LPS-induced DC maturation. This effect was partially (sputa) to significantly (NE) reversed by addition of recombinant secretory leukocyte protease inhibitor. Western Blot analysis showed that purified NE degraded CD86 in mDC lysates in a time- and dose-dependent fashion, and caused shedding of CD86 into the supernatants of mDC cultures. NE treatment also inhibited the antigen-presenting ability of mDCs, as measured by their ability to induce ovalbumin-specific D011.10-transgenic T-cell proliferation.


CONCLUSIONS
Our data indicate that NE in lung inflammatory secretions of patients with COPD/CF may disable DCs and prevent them from mounting an adequate immune response. This may have implications for the infection-driven generation of disease exacerbations in these two pathologies.
Roghanian
Ali
A
Medical Research Council (MRC) Centre for Inflammation Research (CIR), The Queen's Medical Research Institute, Edinburgh University Medical School, Edinburgh, Scotland, United Kingdom.
Drost
Ellen M
EM
MacNee
William
W
Howie
Sarah E M
SE
Sallenave
Jean-Michel
JM
D000328:Adult; D000368:Aged; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D018122:B7-1 Antigen / Q000378:metabolism; D051940:B7-2 Antigen / Q000502:physiology; D015153:Blotting, Western; D019013:CD40 Antigens / Q000378:metabolism; D003550:Cystic Fibrosis / Q000276:immunology / Q000503:physiopathology*; D016207:Cytokines / Q000032:analysis; D003713:Dendritic Cells / Q000276:immunology / Q000502:physiology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019272:Leukocyte Elastase / Q000276:immunology / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D010641:Phenotype; D029424:Pulmonary Disease, Chronic Obstructive / Q000276:immunology / Q000503:physiopathology*; D013183:Sputum / Q000166:cytology
D018122:B7-1 Antigen; D051940:B7-2 Antigen; D019013:CD40 Antigens; D016207:Cytokines; D019272:Leukocyte Elastase