Pro-inflammatory effect of cystic fibrosis sputum microparticles in the murine lung.

BACKGROUND: The role of microparticles (MPs) in the inflammatory process of cystic fibrosis (CF) airways is not known. Here, we have studied the pro-inflammatory potential of CF MPs in a model of acute lung injury. METHODS: Swiss mice were subjected to intratracheal administration of MPs obtained from CF and primary ciliary diskinesia (PCD) patients. Histopathology, total and differential cell counts in bronchoalveolar lavage fluid were used to evaluate the inflammatory reaction in the lung. Lipopolysaccharide (LPS)-like activity of MPs was studied by Limulus amebocyte lysate assay. RESULTS: MPs obtained from acute CF patients determined peribronchial and perivascular inflammatory infiltrates similar to those elicited by LPS. This inflammation was granulocyte-dominated and higher than that determined by MPs obtained from stable CF, whereas PCD MPs caused a macrophage-dominated inflammation. While LPS-activity was not found in circulating blood MPs prepared from CF patients, it was present in MPs obtained from CF sputum and sputum CD66b(+) neutrophils. Finally, LPS-like activity was only detected in circulating MPs after incubation with LPS as well as in MPs obtained from LPS-stimulated neutrophils obtained from healthy donors. CONCLUSIONS: These data suggest that the pro-inflammatory potential of neutrophil-derived MPs in the CF airways may be subsequent to the binding of shedded LPS.

Isolation and characterization of microparticles in sputum from cystic fibrosis patients.

BACKGROUND: Microparticles (MPs) are membrane vesicles released during cell activation and apoptosis. MPs have different biological effects depending on the cell from they originate. Cystic fibrosis (CF) lung disease is characterized by massive neutrophil granulocyte influx in the airways, their activation and eventually apoptosis. We investigated on the presence and phenotype of MPs in the sputum, a rich non-invasive source of inflammation biomarkers, of acute and stable CF adult patients. METHODS: Spontaneous sputum, obtained from 21 CF patients (10 acute and 11 stable) and 7 patients with primary ciliary dyskinesia (PCD), was liquefied with Sputasol. MPs were counted, visualized by electron microscopy, and identified in the supernatants of treated sputum by cytofluorimetry and immunolabelling for leukocyte (CD11a), granulocyte (CD66b), and monocyte-macrophage (CD11b) antigens. RESULTS: Electron microscopy revealed that sputum MPs were in the 100-500 nm range and did not contain bacteria, confirming microbiological tests. CF sputa contained higher number of MPs in comparison with PCD sputa. Levels of CD11a+-and CD66b+-, but not CD11b+-MPs were significantly higher in CF than in PCD, without differences between acute and stable patients. CONCLUSIONS: In summary, MPs are detectable in sputa obtained from CF patients and are predominantly of granulocyte origin. This novel isolation method for MPs from sputum opens a new opportunity for the study of lung pathology in CF.