TFF2 and infection: In agreement with the level of PMN transmigration, when we measured barrier disruption by cross‐epithelial leakage of the protein marker horseradish peroxidase (HRP) and Sp translocation, only WT‐primed Alox15−/− ALI monolayers sustained significant HRP flux and Sp translocation after migration of PMN to HXA3‐containing infection supernatant (Figure 2e,f, “WT + Sp‐inf.