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[The morphological and functional changes of pulmonary intravascular macrophages induced by LPS]
1Institute of Respiratory Diseases, Xingqiao Hospital, Third Military Medical University, Chongqing 400037.
Objective:
To study the roles of pulmonary intravascular macrophages (PIMs) on infective acute lung injury (ALI).
Method:
Porcine pulmonary blood vessels were flushed by modified Morton's method, PIMs were isolated by adhesion method and identified with the features at both light and electron microscopic level. The activity of IL-1 beta, and content of IL-6, IL-8 and TNF alpha in the culture supernatants were measured by thymocyte proliferation or ELISA, respectively.
Result:
Enlarged and increased pseudopods, and increased amount of lysosomes and phagosomes were found in the PIM stimulated with lipopolysaccharide (LPS, 10 micrograms/ml); the releases of TNF alpha, IL-1 beta, IL-6 and IL-8 were increased significantly as compared with the level of pre-stimulation of LPS (P < 0.01), and reaching their peaks at 1 h, 2 h, 4 h and 6 h after LPS stimulation, respectively.
Conclusion:
The isolation of porcine PIMs can be completed with modified Morton's method; the phagocytosis and secretion of PIMs are more active after LPS stimulation. In the pathogenesis of ALI, TNF alpha and IL-1 beta may play an important role at its early stage; however, the IL-6 and IL-8 may be associated with the pathophysiological changes at the later stage of ALI.
Insights
Pulmonary intravascular macrophages (PIMs) show increased activity after lipopolysaccharide (LPS) stimulation, releasing key cytokines. These findings shed light on the role of PIMs in acute lung injury (ALI) pathogenesis.
Area of Science:
- Immunology
- Pulmonary Medicine
- Cell Biology
Background:
- Acute lung injury (ALI) is a critical condition with significant morbidity and mortality.
- Pulmonary intravascular macrophages (PIMs) are key immune cells residing in lung vasculature.
- Understanding PIMs' role in ALI is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the function of PIMs in the context of infective acute lung injury (ALI).
- To characterize PIMs' response to lipopolysaccharide (LPS) stimulation.
- To elucidate the temporal roles of specific cytokines released by PIMs during ALI.
Main Methods:
- Isolation of porcine PIMs using a modified Morton's method and adhesion techniques.
- Morphological identification of PIMs via light and electron microscopy.
- Quantification of cytokine release (TNF-alpha, IL-1 beta, IL-6, IL-8) using ELISA and thymocyte proliferation assays.
Main Results:
- LPS stimulation induced morphological changes in PIMs, including increased pseudopods, lysosomes, and phagosomes.
- Significant increases in TNF-alpha, IL-1 beta, IL-6, and IL-8 release were observed post-LPS stimulation (P < 0.01).
- Cytokine release peaked at different time points: TNF-alpha (1h), IL-1 beta (2h), IL-6 (4h), and IL-8 (6h).
Conclusions:
- The modified Morton's method is effective for isolating porcine PIMs.
- LPS enhances PIM phagocytosis and cytokine secretion.
- TNF-alpha and IL-1 beta are implicated in early ALI stages, while IL-6 and IL-8 are associated with later pathophysiological changes.