Abstract:

AIM: To study the effect of ambroxol hydrochloride on pulmonary fibrosis in rats and its effect on TGF-β/Smad/ERK signal transduction pathway and the imbalance of Th17/Treg cells. METHODS: Thirty male SPF-level Wistar male rats were selected from the Experimental Animal Center of our hospital and were randomly divided into five groups: normal group (10), model group (10), ambroxol low-dose group (10), ambroxol middle-dose(10) and ambroxol high-dose (10) goups. Pulmonary fibrosis model was prepared with 0.2 mL intratracheal perfusion of bleomycin (5 mg/kg). Rats in the low, medium and high dose groups were intraperitoneally injected with 10, 20, 40 mg/kg ambroxol hydrochloride from the first day after operation. Rats in the normal group and the model group were intraperitoneally injected with 3.33 mL/kg normal saline for 14 days. HE staining and Masson staining were performed to observe pathological changes. ELISA was applied to detect TGF-β1. The expression of TFG-β1 in fibroblasts was detected by real-time fluorescent quantitative PCR. The expressions of ERK1/2, p-ERK, Smad3, Smad4 and Smad7 in fibroblasts were detected by Western blot. The expressions of Treg and Th17 cells in the lung tissue of each group were detected by flow cytometry. RESULTS: Compared with normal group, content of TGF-β1 in the fibroblasts, expression of TGF-β1 gene in fibroblasts, expression of ERK1/2, p-ERK, Smad3 and Smad4 protein, and Th17 and Th17/Treg in the lung tissue of the model group were higher than those in the normal group (P<0.05), and those of the middle and high doses of ambroxol were lower than the model group (P<0.05). While the expression of Smad7 protein and Treg cell in the lung tissue in the model group was significantly higher than that in the normal group (P<0.05), and those of the middle and high doses of ambroxol were higher than the model group (P<0.05). CONCLUSION: Ambroxol hydrochloride has anti-pulmonary fibrosis effect by maintaining the balance of Th17/Treg in lung tissue of rats with pulmonary fibrosis and inhibiting the signal transduction of the major cytokines in the TGF-β/Smad/ERK signal transduction pathway in rats.

Key words: pulmonary fibrosis, TGF-β/Smad/ERK signal transduction pathway, Th17/Treg cells, ambroxol hydrochloride