Pulmonary Capillary Confinement Shapes Bacteria-engaging Neutrophil Fate Transition

<title>Abstract</title> <p>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.</p>