Pulmonary Capillary Confinement Shapes Bacteria-engaging Neutrophil Fate Transition

Neutrophils must deform to traverse pulmonary capillaries, yet whether this mechanical confinement shapes their inflammatory state is unclear. Quantitative lung intravital imaging shows that capillary transit is associated with GsMTx4-sensitive Ca²⁺ signals, PAD-linked nuclear remodeling and the emergence of motile anuclear neutrophil-derived cytoplasts. These cytoplasts preferentially associate with Pseudomonas aeruginosa in vivo, suggesting that the pulmonary capillary bed functions as a mechanical checkpoint for early host-microbe interactions.