Traditional Chinese medicine for pulmonary fibrosis therapy: Progress and future prospects

Pulmonary fibrosis (PF) is a chronic, debilitating and often lethal lung disorder. Despite the molecular mechanisms of PF are gradually clear with numerous researchers' efforts, few effective drugs have been developed to reverse human PF or even halt the chronic progression to respiratory failure. Traditional Chinese medicine (TCM), the main component of the medical practice used for more than 5000 years especially in China, often exerts wider action spectrum than previously attempted options in treating human diseases. Recent data have shown the anti-fibrotic benefits of the active ingredients from TCM in this field, which may represent an attractive source of the drug discovery against PF. This review summarizes the pre-clinical and clinical evidence on the benefits of TCM and their active ingredients, and provides a comprehensive information and reliable basis for the exploration of new treatment strategies of botanical drugs in the therapy of PF. The literature information was obtained from the scientific databases on ethnobotany and ethno medicines (up to Aug 2016), mainly from the Pubmed, Web of Science and CNKI databases, and was to identify the experimental studies on the anti-fibrotic role of the active agents from TCM and the involved mechanisms. The search keywords for such work included: "lung fibrosis" or "pulmonary fibrosis", and "traditional Chinese medicine", "extract" or "herb". A number of studies have shown that the active agents of single herbs and TCM formulas, particularly the flavonoids, glycosides and alkaloids, exhibit potential benefits against PF, the mechanisms of which appear to involve the regulation of inflammation, oxidant stress, and pro-fibrotic signaling pathways, etc. Besides, the processing methods for discovering TCM in treating PF were prospectively discussed. These research work have shown the therapeutic benefits of TCM in the treatment of PF. However, more continued researches should be undertaken to clarify the unconfirmed chemical composition and regulatory mechanisms, conduct standard clinical trials, and evaluate the possible side effects. The insights provided in present review will be needed for further exploration of botanical drugs in the development of PF therapy.