CSF2 and pulmonary emphysema: A closer examination of the immune heterogeneity in end-stage COPD via machine-learning assisted analysis, identified an “emphysema inflammatory subgroup (EIS)” characterized by higher levels of antigen-presenting cells, mast cells, and pro-inflammatory mediators (IL-1β, IFN-β, GM-CSF), along with lower pO2 and DLCO%predicted—both independent prognostic markers in COPD.23