Immune cell migration in severe pneumonia

The global migration atlas of immune cells during severe pneumonia is not fully understood. In this study, we conducted comprehensive single-cell analyses of matched lung tissue, bronchoalveolar lavage fluid, and peripheral blood from patients with severe pneumonia. Our observations revealed a migration pattern of activated immune cells from the lung interstitia to the airway (alveoli). Notably, CD8+ TRMs were highly expanded both in the interstitia and airway (alveolar) lumen. They were derived from circulating CX3CR1+ TEMRAs, which upregulated ITGAE and CXCR3 during lung infiltration. Similarly, plasma cells and plasmablasts expressing ITGAE and CXCR3 also demonstrated the capacity to migrate to mucosal regions and the alveolar lumen. The pro-inflammatory macrophages played a pivotal role in recruiting CD8+ TRMs and plasma cells into the airways and alveoli via the CXCL10-CXCR3 axis. Our findings provide a robust foundation for further exploration of the immune cell migrations and interactions during severe pneumonia. <fig><object-id>erj;64/suppl_68/PA5330/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>