We observed a gradient along this factor associated with neutrophilic inflammation, which is highly relevant for identifying subgroups within CF and COPD patients who might benefit from targeted anti-inflammatory interventions including emerging inhibitors of DPP-1/CatC to inhibit increased activity of all three neutrophil serine proteases (NE, PR-3 and CatG) in chronic neutrophilic inflammation63,64. Here, PRTN3 is linked to chronic obstructive pulmonary disease.