Related Experiment Videos
Stimulation of rat and murine alveolar macrophage proliferation by lung fibroblasts
B E Lehnert1, Y E Valdez, N M Lehnert
1Life Sciences Division, Los Alamos National Laboratory, New Mexico 87545.
Abstract:
Increases in alveolar macrophage (AM) number occur during chronic inflammation and pulmonary fibrosis. Although the underlying mechanism(s) for such increases remain poorly understood, the overall process is known to involve the local proliferation of the AM. In the present study, we report that AM lavaged from the lungs of rats and mice proliferate in vitro when grown atop lung fibroblasts (LF) or when they are cultured in the presence of LF-conditioned media. Using murine AM and LF, we additionally show that the LF-derived mitogenic cytokines for the AM are macrophage colony-stimulating factor (M-CSF) and granulocyte/macrophage colony-stimulating factor (GM-CSF). Our findings suggest that LF, via the production of M-CSF and GM-CSF, may play an important role in regulating the size of the AM population during chronic inflammatory/fibrogenic lung disorders, and that the complex cytokine network that results in pulmonary fibrogenesis may involve a "coupled reciprocity" between the lung's AM and LF.
Insights
Lung fibroblasts stimulate alveolar macrophage proliferation through M-CSF and GM-CSF, suggesting a key role in chronic lung inflammation and fibrosis. This interaction highlights a coupled reciprocity between these cells in fibrotic lung disorders.
Area of Science:
- Pulmonary immunology
- Cell biology
- Fibrosis research
Background:
- Alveolar macrophage (AM) populations expand during chronic lung inflammation and fibrosis.
- The mechanisms driving AM proliferation in these conditions are not fully understood.
Purpose of the Study:
- To investigate the role of lung fibroblasts (LF) in regulating alveolar macrophage proliferation.
- To identify specific factors produced by LF that stimulate AM growth.
Main Methods:
- In vitro culture of rodent AM and LF.
- Assessment of AM proliferation in co-culture and in response to LF-conditioned media.
- Identification of mitogenic cytokines using murine models.
Main Results:
- AM demonstrated increased proliferation when cultured on LF or in LF-conditioned media.
- Macrophage colony-stimulating factor (M-CSF) and granulocyte/macrophage colony-stimulating factor (GM-CSF) were identified as key LF-derived mitogens for AM.
- These findings indicate LF actively promote AM proliferation.
Conclusions:
- Lung fibroblasts, through M-CSF and GM-CSF, significantly influence AM population size.
- This suggests a reciprocal interaction between AM and LF in the pathogenesis of chronic inflammatory and fibrogenic lung diseases.
- Understanding this cellular crosstalk is crucial for developing therapies for pulmonary fibrosis.