Siqing et al. showed that Erchen decoction may upregulate the expression of the HDAC2 gene in peripheral blood mononuclear cells (PBMCs) and inhibit the transcription and translation of the TGF-β1 gene, thereby antagonizing airway inflammation in COPD rats and protecting the lung tissue [40]. Here, HDAC2 is linked to chronic obstructive pulmonary disease.