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MRP8/MRP14, CD11b and HLA-DR expression of alveolar macrophages in pneumonia
F Bühling1, A Ittenson, D Kaiser
1Institute of Immunology, Otto von Guericke University Magdeburg, Leipziger-Strasse 44, Magdeburg, Germany. frank.buehling@medizin.uni-magdeburg.de
Abstract:
Activation of alveolar macrophages is characterised by specific alterations to the expression pattern of surface markers under certain pathological conditions. MRP8/MRP14 and CD11b are involved in the regulation of macrophage migration and adhesion. HLA-DR regulates the antigen presentation by alveolar macrophages. The aim of this study was to investigate the phenotype of alveolar macrophages in pneumonia particularly in relationship to the changes in concentrations of TGF-beta1 and IL-8. Using cytofluorimetry, we analysed the surface expression of MRP8/MRP14, CD11b, and HLA-DR on alveolar macrophages of 42 pneumonia (PN) patients, 14 patients with interstitial lung diseases (ILD), five patients with chronic obstructive lung disease (COPD), and 58 patients without lung disease. Phenotypic characteristics were correlated to the concentration of TGF-beta1 and IL-8 in the bronchoalveolar lavage fluid (BALF) of the same patients. The direct influence of TGF-beta1 and IL-8 on expression of MRP8/MRP14, CD11b and HLA-DR of cultured monocytes and MonoMac cells was analysed. Significantly more MRP8/MRP14 and CD11b positive macrophages and less HLA-DR-positive macrophages were found in PN but not in ILD or COPD. The percentage of CD11b-positive macrophages correlated with the TGF-beta1 as well as the IL-8 concentrations. The amount of HLA-DR-positive macrophages correlated negatively to the concentration of TGF-beta1 and IL-8. These findings document a significant activation of alveolar macrophages during pneumonia. TGF-beta1 led to a modulation of HLA-DR and MRP8/MRP14-antigen expression in vitro. In conclusion, it was shown that in pneumonia but not in ILD or COPD alveolar macrophages were characterised by an increased MRP8/MRP14 and CD11b expression and a diminished HLA-DR expression. The characterisation of subpopulations within the alveolar macrophages may be a useful tool for the monitoring of disease progression.
Insights
Pneumonia activates alveolar macrophages, increasing MRP8/MRP14 and CD11b expression while decreasing HLA-DR. These changes correlate with TGF-beta1 and IL-8 levels, aiding disease monitoring.
Area of Science:
- Immunology
- Pulmonology
- Cell Biology
Background:
- Alveolar macrophage surface marker expression changes in pathological conditions.
- MRP8/MRP14, CD11b, and HLA-DR are key markers involved in macrophage function.
- Cytokines like TGF-beta1 and IL-8 may influence macrophage phenotype in lung diseases.
Purpose of the Study:
- To investigate alveolar macrophage phenotype in pneumonia.
- To correlate macrophage surface marker expression with TGF-beta1 and IL-8 levels.
- To assess the in vitro effects of TGF-beta1 and IL-8 on macrophage markers.
Main Methods:
- Cytofluorimetry analysis of alveolar macrophage surface markers (MRP8/MRP14, CD11b, HLA-DR).
- Analysis of bronchoalveolar lavage fluid (BALF) for TGF-beta1 and IL-8 concentrations.
- In vitro studies on cultured monocytes and MonoMac cells exposed to TGF-beta1 and IL-8.
Main Results:
- Pneumonia patients showed significantly increased MRP8/MRP14 and CD11b positive macrophages, and decreased HLA-DR positive macrophages compared to controls, ILD, and COPD.
- CD11b expression correlated positively with TGF-beta1 and IL-8 concentrations.
- HLA-DR expression correlated negatively with TGF-beta1 and IL-8 concentrations; TGF-beta1 modulated HLA-DR and MRP8/MRP14 expression in vitro.
Conclusions:
- Alveolar macrophages in pneumonia exhibit a distinct phenotype characterized by increased MRP8/MRP14 and CD11b, and decreased HLA-DR expression.
- These phenotypic changes are associated with elevated TGF-beta1 and IL-8 levels.
- Characterizing alveolar macrophage subpopulations may serve as a valuable tool for monitoring pneumonia progression.