Water Extract of Gallnut Reduces the Injury of Alveolar Epithelial Cells Induced by Streptococcus pneumoniae by Up-Regulating miRNA-338-3p

Abstract

Streptococcus pneumoniae (S. pneumoniae) is the primary pathogen causing pneumonia, in addition to lobar pneumonia, meningitis, bronchitis, and other diseases. Inhibiting the apoptosis and inflammation of alveolar epithelial cells is essential for the treatment of pneumonia caused by S. pneumoniae. Traditional Chinese medicine has the characteristics of multiple components, multiple targets, and few adverse reactions. It is recognized by doctors and patients in the treatment of pneumonia and other diseases. We conducted this study to explore the effect of the water extract of gallnut on alveolar epithelial cells affected by S. pneumoniae. Studies have found that the water extract of gallnut can increase the optical density value, Bcl-2 protein expression, IL-10 content, and miRNA-338-3p levels of alveolar epithelial cells affected by S. pneumoniae. Additionally, it can reduce the rate of cell apoptosis, Bax protein expression, and IL-6 content. Further, its effect is dose-dependent: the higher the concentration of gallnut water extract, the more evident its effect on alveolar epithelial cells. Through nano PCR detection, it was found that overexpression of miRNA-338-3p can increase the activity of alveolar epithelial cells affected by S. pneumoniae and promote cell growth. Knockdown of miRNA-338-3p reduced the impact of the water extract of gallnut on the growth of alveolar epithelial cells and the expression of inflammatory factors affected by S. pneumoniae. Therefore, our findings suggest that the water extract of gallnut could inhibit the apoptosis of alveolar epithelial cells affected by S. pneumoniae by up-regulating the expression of miRNA-338-3p.