Transcriptomic responses of lung mesenchymal cells during pneumonia

Area of Science:

• Immunology
• Cell Biology
• Respiratory Medicine

Background:

• The function of mesenchymal cells in lung infections is poorly understood.
• Specific mesenchymal cell types and their responses during respiratory infections require clarification.

Purpose of the Study:

• To investigate the diverse roles and responses of lung mesenchymal cells during pneumococcal pneumonia.
• To characterize the transcriptomic changes in different mesenchymal cell subsets during infection and resolution.

Main Methods:

• Single-cell RNA sequencing was performed on lung mesenchymal cells from mice in naive, pneumonic, and resolved infection states.
• Mesenchymal cells were classified into distinct subtypes including fibroblasts, myofibroblasts, pericytes, smooth muscle cells, and mesothelial cells.
• Transcriptomic profiles were analyzed to identify cell-type-specific and conserved responses to infection.

Main Results:

• Mesenchymal cells returned to baseline transcriptomes after infection resolution.
• All mesenchymal cell types exhibited altered transcriptomes during pneumonia, indicating both conserved and distinct responses.
• Fibroblasts, particularly alveolar fibroblasts, showed significant and specific gene expression changes, highlighting their immune roles.

Conclusions:

• Lung mesenchymal cells display specialized immune activities during respiratory infections.
• Alveolar and adventitial fibroblasts exhibit differential responses, with alveolar fibroblasts being more responsive.
• These findings reveal the complex and varied contributions of mesenchymal cells to lung immunity during infection.