Metformin attenuates silica-induced pulmonary fibrosis via AMPK signaling. Cheng Demin,Xu Qi,Wang Yue,Li Guanru,Sun Wenqing,Ma Dongyu,Zhou Siyun,Liu Yi,Han Lei,Ni Chunhui Journal of translational medicine BACKGROUND:Silicosis is one of the most common occupational pulmonary fibrosis caused by respirable silica-based particle exposure, with no ideal drugs at present. Metformin, a commonly used biguanide antidiabetic agent, could activate AMP-activated protein kinase (AMPK) to exert its pharmacological action. Therefore, we sought to investigate the role of metformin in silica-induced lung fibrosis. METHODS:The anti-fibrotic role of metformin was assessed in 50 mg/kg silica-induced lung fibrosis model. Silicon dioxide (SiO)-stimulated lung epithelial cells/macrophages and transforming growth factor-beta 1 (TGF-β1)-induced differentiated lung fibroblasts were used for in vitro models. RESULTS:At the concentration of 300 mg/kg in the mouse model, metformin significantly reduced lung inflammation and fibrosis in SiO-instilled mice at the early and late fibrotic stages. Besides, metformin (range 2-10 mM) reversed SiO-induced cell toxicity, oxidative stress, and epithelial-mesenchymal transition process in epithelial cells (A549 and HBE), inhibited inflammation response in macrophages (THP-1), and alleviated TGF-β1-stimulated fibroblast activation in lung fibroblasts (MRC-5) via an AMPK-dependent pathway. CONCLUSIONS:In this study, we identified that metformin might be a potential drug for silicosis treatment. 10.1186/s12967-021-03036-5

Microcystin-LR ameliorates pulmonary fibrosis via modulating CD206 M2-like macrophage polarization. Wang Jie,Xu Lizhi,Xiang Zou,Ren Yan,Zheng Xiufen,Zhao Qingya,Zhou Qunzhi,Zhou Yuefen,Xu Lin,Wang Yaping Cell death & disease Idiopathic pulmonary fibrosis (IPF) is a group of chronic interstitial pulmonary diseases characterized by myofibroblast proliferation and extracellular matrix deposition with limited treatment options. Based on our previous observation, we hypothesized microcystin-leucine arginine (LR), an environmental cyanobacterial toxin, could potentially suppress pulmonary fibrosis. In this study, we first demonstrated that chronic exposure of microcystin-LR by oral for weeks indeed attenuated the pulmonary fibrosis both on bleomycin-induced rat and fluorescein isothiocyanate-induced mouse models. Our data further indicated that treatment with microcystin-LR substantially reduced TGF-β1/Smad signaling in rat pulmonary tissues. The experiments in vitro found that microcystin-LR was capable of blocking epithelial-mesenchymal transition (EMT) and fibroblast-myofibroblast transition (FMT) through suppressing the differentiation of CD206 macrophages. Mechanically, microcystin-LR was found to bind to glucose-regulated protein 78 kDa (GRP78) and suppress endoplasmic reticulum unfolded protein response (UPR) signaling pathways. These events led to the modulation of M2 polarization of macrophages, which eventually contributed to the alleviation of pulmonary fibrosis. Our results revealed a novel mechanism that may account for therapeutic effect of microcystin-LR on IPF. 10.1038/s41419-020-2329-z

Paeoniflorin suppresses TGF-β mediated epithelial-mesenchymal transition in pulmonary fibrosis through a Smad-dependent pathway. Ji Yu,Dou Yan-Nong,Zhao Qian-Wen,Zhang Ji-Zhou,Yang Yan,Wang Ting,Xia Yu-Feng,Dai Yue,Wei Zhi-Feng Acta pharmacologica Sinica AIM:Paeoniflorin has shown to attenuate bleomycin-induced pulmonary fibrosis (PF) in mice. Because the epithelial-mesenchymal transition (EMT) in type 2 lung endothelial cells contributes to excessive fibroblasts and myofibroblasts during multiple fibrosis of tissues, we investigated the effects of paeoniflorin on TGF-β mediated pulmonary EMT in bleomycin-induced PF mice. METHODS:PF was induced in mice by intratracheal instillation of bleomycin (5 mg/kg). The mice were orally treated with paeoniflorin or prednisone for 21 d. After the mice were sacrificed, lung tissues were collected for analysis. An in vitro EMT model was established in alveolar epithelial cells (A549 cells) incubated with TGF-β1 (2 ng/mL). EMT identification and the expression of related proteins were performed using immunohistochemistry, transwell assay, ELISA, Western blot and RT-qPCR. RESULTS:In PF mice, paeoniflorin (50, 100 mg·kg(-1)·d(-1)) or prednisone (6 mg·kg(-1)·d(-1)) significantly decreased the expression of FSP-1 and α-SMA, and increased the expression of E-cadherin in lung tissues. In A549 cells, TGF-β1 stimulation induced EMT, as shown by the changes in cell morphology, the increased cell migration, and the increased vimentin and α-SMA expression as well as type I and type III collagen levels, and by the decreased E-cadherin expression. In contrast, effects of paeoniflorin on EMT disappeared when the A549 cells were pretreated with TGF-β1 for 24 h. TGF-β1 stimulation markedly increased the expression of Snail and activated Smad2/3, Akt, ERK, JNK and p38 MAPK in A549 cells. Co-incubation with paeoniflorin (1-30 μmol/L) dose-dependently attenuated TGF-β1-induced expression of Snail and activation of Smad2/3, but slightly affected TGF-β1-induced activation of Akt, ERK, JNK and p38 MAPK. Moreover, paeoniflorin markedly increased Smad7 level, and decreased ALK5 level in A549 cells. CONCLUSION:Paeoniflorin suppresses the early stages of TGF-β mediated EMT in alveolar epithelial cells, likely by decreasing the expression of the transcription factors Snail via a Smad-dependent pathway involving the up-regulation of Smad7. 10.1038/aps.2016.36