CD44 and chronic obstructive pulmonary disease: Functionally, Macro_SPP1 cells in COPD exhibited higher anti-inflammatory scores but lower phagocytosis scores, with elevated expression of immunosuppressive genes (e.g., IL1RN, CCL18, CD274, IL4I1, and IDO1) but decreased expression of efferocytosis-related genes (e.g., LRP1, PECAM1, CD44, SIGLEC1, ICAM1, and FCGR3A) (Figures 6C, F).