Yifei Jianpi recipe improves cigarette smoke-induced inflammatory injury and mucus hypersecretion in human bronchial epithelial cells by inhibiting the TLR4/NF-κB signaling pathway

Abstract

To explore the mechanism of Yifei Jianpi recipe for improving cigarette smoke- induced inflammatory injury and mucus hypersecretion in cultured human bronchial epithelial cells. Serum samples were collected from 40 SD rats treated with Yifei Jianpi recipe (n=20) or normal saline (n=20) by gavage. Cultured human bronchial epithelial 16HBE cells were stimulated with an aqueous cigarette smoke extract (CSE), followed by treatment with the collected serum at different dilutions. The optimal concentration and treatment time of CSE and the medicated serum for cell treatment were determined with CCK-8 assay. The expressions of TLR4, NF-κB, MUC5AC, MUC7, and muc8 at both the mRNA and protein levels in the treated cells were examined with RT- qPCR and Western blotting, and the effects of TLR4 gene silencing and overexpression on their expressions were assessed. The expressions of TNF-α, IL-1 β, IL-6 and IL-8 in the cells were detected using ELISA. At the optimal concentration of 20%, treatment with the medicated serum for 24 h significantly lowered the mRNA and protein expressions of TLR4, NF- κB, MUC5AC, MUC7, and MUC8 in CSE- exposed 16HBE cells, and these effects were further enhanced by TLR4 silencing in the cells. In 16HBE cells with TLR4 overexpression, the expressions of TLR4, NF-κB, MUC5AC, MUC7, and MUC8 were significantly increased after CSE exposure and were lowered following treatment with the medicated serum (P < 0.05). The medicated serum also significantly lowered the levels of TNF-α, IL-1β, IL-6 and IL-8 in CSE-exposed 16HBE cells (P < 0.05). In the 16HBE cell model of chronic obstructive pulmonary disease (COPD), treatment with Yifei Jianpi recipe-medicated serum improves inflammation and mucus hypersecretion possibly by reducing MUC secretion and inhibiting the TLR4/NF-κB signaling pathway.