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Collagen-producing mesothelial cells in adriamycin-induced pleuritis in rat. Microautoradiographic study utilizing
1Department of Pathology, Osaka Medical College, Japan.
Abstract:
By the microautoradiographic method using 3H-proline, collagen production by mesothelial cells was investigated in adriamycin-induced pleuritis in rats. In subpleural granulation tissue formed at 4 to 7 days after the intrapleural injection of adriamycin, proliferating fibroblasts and primitive mesenchymal cells were most intensely labeled, and abundant deposition of collagen and acid mucopolysaccharides were demonstrated about these cells. It is thus concluded that these subpleural mesenchymal cells are mainly responsible for the fibrosing process. Labeling was also observed in some reactive mesothelial cells and macrophages free-floating in the pleural exudate. Several ultrastructural differences between labeled mesothelial cells floating in the fluid and lining the pleural surface were confirmed, suggesting a change in ability to synthesize collagen during mesothelial desquamation. It seems likely that these labeled mononuclear cells in the effusion, attached to the pleural wound surface, support fibrosis performed by underlying collagen-synthesizing mesenchymal cells. Pleural fibrosis disappeared by 10 days, when mesothelial regeneration was almost complete. Probably this change may be due to fibrinolytic activity caused by regenerative mesothelial cells derived from subpleural mesenchymal cells.
Insights
Adriamycin-induced pleuritis in rats reveals subpleural mesenchymal cells drive fibrosis by producing collagen. Regenerative mesothelial cells may resolve fibrosis through fibrinolytic activity.
Area of Science:
- Cell Biology
- Histology
- Pathology
Background:
- Mesothelial cells line serous cavities and play roles in inflammation and repair.
- Adriamycin can induce pleural inflammation and fibrosis.
Purpose of the Study:
- To investigate collagen production by mesothelial cells in adriamycin-induced pleuritis.
- To identify the primary cells responsible for fibrosing processes in the pleura.
Main Methods:
- Microautoradiography using 3H-proline to label collagen production.
- Histological examination of pleural tissue and exudate in rats.
Main Results:
- Subpleural mesenchymal cells and fibroblasts showed intense collagen production in granulation tissue.
- Reactive mesothelial cells and macrophages in pleural exudate also exhibited collagen synthesis.
- Collagen deposition was associated with mesenchymal cell proliferation.
- Pleural fibrosis resolved as mesothelial regeneration occurred.
Conclusions:
- Subpleural mesenchymal cells are the main contributors to pleural fibrosis.
- Mesothelial cells, particularly those in the exudate, may influence fibrosis.
- Regenerative mesothelial cells might resolve fibrosis via fibrinolytic activity.