Paeoniflorin suppresses TGF-β mediated epithelial-mesenchymal transition in pulmonary fibrosis through a Smad-dependent pathway

Abstract

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.

M2 macrophages induce EMT through the TGF‐β/Smad2 signaling pathway

“…TGF‐β is regarded as the causative cytokine for induction of both in vitro and in vivo EMT, and TGF‐β can be secreted by macrophages, lung epithelial cells, and fibroblasts during the development of pulmonary fibrosis (Halwani et al, ). The TGF‐β/Smad2 signaling pathway has been reported to induce EMT and fibrosis through Smad‐ or non‐Smad signaling pathways (Ji et al, ; Zhang et al, ). It has been demonstrated that TGF‐β induces EMT in alveolar epithelial cells both in vivo and in vitro via Smad2 activation (Chen et al, ).…”

Mitigation of TGF-β/Smad signaling pathway-associated liver fibrosis by paeoniflorin

“…It does appear, based on the findings in this study that PF might be the major phytochemical entity in Paeonia lactiflora and Astragalus membranaceus extracts responsible for the anti-fibrotic bioactivity. This views is supported by the fact that it had similar effects on both pulmonary [5,6] and renal interstitial fibrosis [7].…”

“…Paeoniflorin (PF), isolated from Corte moutan, is a major bioactive compound with antiinflammatory and immune-regulatory effects [3,4]. The anti-fibrotic effect of PF has been studied on both pulmonary [5,6] and renal interstitial fibrosis [7]. Studies of the effect of PF'on Schistosomiasis japonica-induced liver fibrosis have also been carried out [8,9].…”

Preventive Effects of the Intestine Function Recovery Decoction, a Traditional Chinese Medicine, on Postoperative Intra-Abdominal Adhesion Formation in a Rat Model

“…Thus, it may be effective in preventing adhesion by inhibiting the inflammatory reaction and cytokines induction caused by injury. In the IFRD, some constituents including Codonopsis Radix (Dangshen) [28], Atractylodes Rhizoma (Baizhu) [29], and Paeoniae Rubra Radix (Chishao) [30] were reported to have anti-inflammatory and antioxidative effects. Jia and He [31] indicated that paeoniflorin, a chemical constituent of Paeoniae Rubra Radix, ameliorated disease in rat models of rheumatoid arthritis by suppressing oxidative stress and inflammation and reducing COX-2 protein expression.…”

“…Fibroblast cells are crucial for ECM deposition; once activated, they differentiate into myofibroblasts that express α -SMA [30]. A hallmark of myofibroblast activation, α -SMA, is typically used to assess the level of fibrosis [36], and positive staining of α -SMA reveals the development of fibrosis.…”