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Updated: Jan 18, 2026
Multicellular Human Alveolar Model Composed of Epithelial Cells and Primary Immune Cells for Hazard Assessment
Published on: May 6, 2020
Intercellular communication between alveolar epithelial cells and macrophages
Anja Beckmann1, Alexander Grissmer1, Carola Meier1
1Department of Anatomy and Cell Biology, Saarland University, Homburg, Saar, Germany.
Background:
The alveolus in the lung tissue is an extremely vulnerable site. Alveolar macrophages control this micro-environment both in states of health and illnesssuch as acute lung injury and infection. It has been reported in mice in vivo that intercellular communication between alveolar macrophages and alveolar epithelial cells is mediated by gap junctions. However, little is known about thismicro-environment in human cells.
Methods:
Since this gap junctional intercellular communication is hard to investigate in human tissues, a co-culture model of two human cell lines, one of epithelial and one of macrophage origin, was used. Immunoblot analysis, freeze fracture replica immunolabeling and electron microscopy were performed.
Results:
Connexin (Cx) 43 protein expression as well as ultrastructurally defined Cx43 gap junctions were detected in co-cultures, yielding evidence of intercellular gap junctions between human alveolar cells of two distinct entities.
Conclusion:
Alveolar macrophages possibly have direct access to the alveolar epithelium via gap junctions in humans, enabling the orchestration of the microenvironment in physiology and disease states.
Insights
Human alveolar macrophages communicate with alveolar epithelial cells via gap junctions. This intercellular communication is crucial for regulating the lung micro-environment in health and disease.
Area of Science:
- Cell biology
- Pulmonology
- Immunology
Background:
- The alveolus is a vulnerable lung site.
- Alveolar macrophages regulate the lung micro-environment in health and disease.
- Intercellular communication via gap junctions between alveolar macrophages and epithelial cells is known in mice but poorly understood in humans.
Purpose of the Study:
- To investigate gap junctional intercellular communication between human alveolar macrophages and epithelial cells.
Main Methods:
- Co-culture model of human epithelial and macrophage cell lines.
- Immunoblot analysis.
- Freeze fracture replica immunolabeling and electron microscopy.
Main Results:
- Connexin (Cx) 43 protein expression was detected.
- Ultrastructurally defined Cx43 gap junctions were identified between human alveolar cells.
- Evidence of intercellular gap junctions between distinct human alveolar cell types was found.
Conclusions:
- Human alveolar macrophages may directly communicate with the alveolar epithelium through gap junctions.
- This communication pathway could orchestrate the lung micro-environment in both physiological and pathological conditions.
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