Regulation Effect of a Chinese Herbal Formula on Flora and Mucosal Immune Secretory Immunoglobulin A in Rats

Flora and mucosal immunity are considered to be the barrier, which is associated with multiple respiratory diseases, including recurrent respiratory tract infection (RRTI). Fei-Xi-Tiao-Zhi-Fang (FTF) is a traditional Chinese herbal formula used in the treatment of RRTI. However, the mechanism is little known. This study aims to identify the function of FTF in flora and mucosal immune secretory immunoglobulin A (sIgA) in the model of RRTI rats. The samples of intestine and lung were collected to detect sIgA, short chain fatty acids (SCFAS), and flora with enzyme-linked immunosorbent assay (ELISA), gas chromatography, and 16S rDNA sequencing. The body weight and viscera index were increased dynamically in RRTI rats after the administration of FTF. Furthermore, the types and proportions of aboriginal flora were significantly changed in the model group, whereas the altered flora was rescued in the FTF administration group. Desulfovibrio increased in the intestinal microflora and Ralstonia and Blautia decreased in the pulmonary microflora at the genus level, similar to that in the normal group. In addition, the expressions of sIgA in pulmonary and intestinal tissues were significantly upregulated and the level of SCFAS was increased in FTF group compared to the RRTI model group. Our study suggests that FTF can alleviate the symptoms of RRTI by increasing sIgA and SCFAS, recovering flora, and improving the immunity.