TGFB1 and congenital rubella syndrome: In vitro experiments, cigarette smoke, an important pathogenic factor for CRS, can cause a significant increase in mRNA expression of inflammatory factor TGF-β1 and MMP-9 activity and decrease of CFTR and BK channel activities in primary human airway epithelial cells, thus reducing ASL volumes and increasing mucus concentrations (Sailland et al., 2017; Kim et al., 2021).