Mechanism underlying the role of Miaoyao Fanggan sachet in up-regulating respiratory tract immunity through TLR-MyD88-NFκB signaling pathway

Abstract

Background To elucidate the mechanism underlying the role of Miaoyao Fanggan sachet (MFS) in improving respiratory immunity through the TLR-MyD88-NFκB signaling pathway in MyD88 knockout mouse models and human normal lung epithelial cell line (BEAS-2B).Methods Sixteen male C57BL/6J mice (SPF grade) were randomly divided into the control (n = 8) and MFS groups (n = 8) and 16 male MyD88 knockout mice were randomly assigned into the MyD88 knockout (MyD88-KO group, n = 8) and MyD88 KO + MFS groups (n = 8). Mice in the MFS intervention group were continuously treated with MFS inhalation from 8:00 am to 8:00 pm for 30 d and the sachets were replaced every 6 d. Hematoxylin-eosin (H.E.) staining was used to observe the pathological changes of lung tissues. The expression levels of TAK1, NFκB p65, IκB and IL6 in mouse lung tissues were detected by immunohistochemical staining, immunofluorescent staining, Western blot and qRT-PCR, respectively.Results Mikawa’s lung injury score did not significantly differ between the control and MFS groups (both P > 0.05). The parameters related to liver and kidney function did not significantly differ among four groups (all P > 0.05). The TAK1, NFκB p65, IκB and IL6 mRNA and protein in the MFS group were significantly up-regulated than those in the other groups (all P < 0.05). Compared with the MyD88-KO group, they were significantly up-regulated in the MyD88-KO + MFS group (P < 0.05).Conclusion HFS can improve the respiratory immunity probably by up-regulating the expression level of MyD88, activating the TLR-MyD88-NFκB signaling pathway and stimulating the release of cytokines in the downstream pathway.