Traditional Chinese Medicine Clerodendrum japonicum (C. japonicum) Ameliorates the Pulmonary Fibrosis through Inhibiting the TGF-β/Smad3 Signaling Pathway

Clerodendrum japonicum (C. japonicum) is a classical Traditional Chinese Medicine (TCM) and has been used to treat the dozens of diseases in China. However, scientific evidence for the pulmonary fibrosis (PF) treatment of C. japonicum used in traditional medicine is lacking. This study evaluated whether C. japonicum ameliorates the PF and the potential molecular mechanism of C. japonicum treatment in vivo and in vitro. We used the PF rat model in vivo. The lung coefficient, HE and Masson staining were used to evaluate the lung tissues injury. Transmission electron microscope (TEM) was used to evaluate the organelle structural changes. The inflammatory cytokines IL-1β, IL-6, MCP-1 and TNF-α were detected using ELISA assay. ROS, MDA and GSH were measured to explore the oxidative stress. Western blotting, immunofluorescence (IF) and RT-qPCR were performed to observe the expressions of PF and TGF-β/Smad3 signaling pathway related genes and proteins. Firstly, C. japonicum could effectively alleviate the PF injury in rat model. C. japonicum could effectively inhibit the levels of inflammatory factors in PF animal model, at the same time, C. japonicum could reasonably regulate oxidative stress factors in PF animal model. Furthermore, TGF-β/Smad3 signaling pathway was involved in the PF animal model and C. japonicum could inhibit the TGF-β/Smad3 signaling pathway in PF treatment effectively. C. japonicum might attenuate the PF in the PF rat model in vivo through inhibiting the TGF-β/Smad3 signaling pathway. These findings suggested that C. japonicum might act as a promising TCM to treat the PF.