HDAC2 and chronic obstructive pulmonary disease: While, selective STING stimulant, 2’,3’-cGAMP, significantly reduced HDAC2 expression in healthy fibroblasts in comparison to CSE (Fig 4B), the combination of STING inhibitor and dexamethasone in COPD fibroblasts reversed the steroid hyporesponsiveness through upregulation of HDAC2 (Fig 4C).