Improvement of Idiopathic Pulmonary Fibrosis Through a Combination of Radix and Radix Via Mammalian Target of Rapamycin Signaling Pathway-induced Autophagy in Rat

Background: There is a major need for effective, well-tolerated treatments for idiopathic pulmonary fibrosis (IPF) in clinic. radix (AR; Huangqi) and radix (AS; Danggui) have been frequently used in the treatment of IPF. This study aimed to reveal the pharmacological effects and the mechanisms of the action of an AR-AS combination in treating IPF.

Methods: Sprague-Dawley rats were randomly divided into six groups (n=5): control, bleomycin (BLM) model, AR, AS, AR + AS, and prednisone (PDN) groups. A transforming growth factor-β1 (TGF-β1)-induced MRC-5 cell model were also used. Pulmonary fibrosis, inflammation, oxidative stress, and autophagy were evaluated by performing hematoxylin and eosin (H&E) staining, Masson staining, immunohistochemical staining, quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, enzyme-linked immunosorbent assay (ELISA), immunofluorescence, and hydroxyproline assay following the treatment of AR, AS, and the AR-AS herb pair.

Results: Rats administered the AR-AS herb pair had lower α-smooth muscle actin (α-SMA), collagen I, fibronectin, and vimentin levels in lung tissues, and lower inflammatory cytokine levels in rat serum. In addition, the AR-AS herb pair induced mammalian target of rapamycin (mTOR)-mediated autophagy and reduced oxidative stress in BLM-induced rats. The effects of the AR and AS combination were confirmed in MRC-5 cells treated with TGF-β1. Specifically, the combination of AR and AS attenuated MRC-5 cell fibrosis, inflammation, and oxidative stress while inducing autophagy.

Conclusions: The combination of AR and AS protects against IPF by inducing autophagy via inhibiting the mTOR signaling pathway. The synergistic action of AR and AS is superior to that of either AR or AS alone.