TREM2 and chronic obstructive pulmonary disease: In recent years, TREM2 has garnered widespread attention owing to its role in the pathogenesis of various pulmonary diseases, including chronic obstructive pulmonary disease (COPD) (24), idiopathic pulmonary fibrosis (IPF) (114), acute lung injury (ALI) (115, 116), acute respiratory distress syndrome (ARDS) (115, 116), and tuberculosis (TB) (117).