GGA (geranylgeranylacetone) ameliorates bleomycin-induced lung inflammation and pulmonary fibrosis by inhibiting apoptosis and oxidative stress.

BACKGROUND: Fibrosis is a response to ongoing cellular injury, disruption, and tissue remodeling, the pathogenesis of which is unknown, and is characterized by extracellular matrix deposition. The antifibrotic effect of Geranylgeranylacetone (GGA), as an inducer of Heat shock protein 70 (HSP70), in liver, kidney and pulmonary fibrosis has been supported by multiple preclinical evidence. However, despite advances in our understanding, the precise roles of HSP70 in fibrosis require further investigation. The purpose of this study was to investigate whether GGA could participate in the progression of pulmonary fibrosis in mice through apoptosis, oxidative stress and inflammation. METHODS AND RESULTS: B-cell lymphoma-2(Bcl-2) and Bcl2-Associated X (Bax) are two proteins related to apoptosis. Anti-apoptotic factor Bcl-2 and pro-apoptotic factor Bax are often involved in the apoptotic process in the form of dimer. Immunofluorescence and Western blot results showed that bleomycin (BLM) and transforming growth factor-ß (TGF-ß) inhibited Bcl-2 expression and promoted Bax expression in vitro and in vivo, respectively. In contrast, GGA treatment reverses this change. Reactive oxygen species (ROS), Malondialdehyde (MDA) and superoxide dismutase (SOD) are markers of oxidative stress, which often reflect oxidative injury of cells. The detection of ROS, MDA and SOD expression showed that TGF-ß and BLM treatment could significantly promote oxidative stress, while GGA treatment could alleviate oxidative stress damage. In addition, BLM significantly elevated Tumor necrosis factor-α(TNF-α), Interleukin1ß (IL-1ß) and Interleukin 6 (IL-6), while scutellarin reversed the above alterations except for that of GGA. RESULTS: Taken together, GGA suppressed apoptotic, oxidative stress and inflammation in BLM-induced pulmonary fibrosis.

Tumor necrosis factor-α coordinates with transforming growth factor-ß1 to induce epithelial-mesenchymal transition and migration via the NF-κB/NOX4 pathway in bronchial epithelial cells.

BACKGROUND: Epithelial-to-mesenchymal transition (EMT) is the process by which epithelial cells transform into mesenchymal cells, which plays a significant role in lung fibrotic disease. Transforming growth factor-ß1(TGF-ß1) is considered to be the most effective EMT inducer. The purpose of this study was to investigate the effect of the proinflammatory cytokine tumor necrosis factor-α (TNF-α) on TGF-ß1-induced EMT and the underlying mechanisms in the human bronchial epithelial cell line BEAS-2B. METHODS: Human bronchial epithelial BEAS-2B cells were treated with TGF-ß1 and TNF-α separately or in combination for 24 h, and qRT-PCR, western blotting, immunofluorescence staining, and migration assays were used to investigate the EMT process. Moreover, to further explore the effect of the NF-κB pathway on the EMT process, inhibitor assays (BAY-117082, NF-κB inhibitor), wound healing assays, and western blotting were performed. RESULTS: The results showed that both cytokines enhanced the transformation of BEAS-2B cells from epithelial to mesenchymal cells. In addition, combined treatment with TNF-α and TGF-ß1 further reduced E-cadherin expression, which conversely elevated α-SMA and vimentin mRNA and protein levels. Correspondingly, the migration rate of BEAS-2B cells was also increased. Furthermore, inhibiting the NF-κB signaling pathway blocked the expression of EMT-related markers and NOX4 induced by TGF-ß1 and TNF-α, as well as cell migration. CONCLUSION: Taken together, TNF-α and TGF-ß1 cooperatively promoted EMT and cell migration in BEAS-2B cells through the NF-κB/NOX4 signaling pathway.

Geranylgeranylacetone, an inducer of heat shock protein 70, attenuates pulmonary fibrosis via inhibiting NF-κB/NOX4/ROS signalling pathway in vitro and in vivo.

Idiopathic pulmonary fibrosis (IPF) is a devastating and progressive pulmonary disease which is characterized by epithelial cell damage and extracellular collagen deposition. To date, the therapeutic options for IPF are still very limited, so the relevant mechanisms need to be explored. Heat shock protein 70 (HSP70), which has protective versus antitumor effects on cells under stress, is a member of the heat shock protein family. In the current study, qRT-PCR, western blotting, immunofluorescence staining, and migration assays were used to explore the Epithelial-mesenchymal transition (EMT) process in BEAS-2B cells. Moreover, the role of GGA in the process of pulmonary fibrosis was detected by HE, Masson staining, pulmonary function test and immunohistochemistry in C57BL/6 mice. Our results indicated that GGA, as an inducer of HSP70, enhanced the transformation of BEAS-2B cells from epithelial to mesenchymal cells through the NF-κB/NOX4/ROS (reactive oxygen species) signalling pathway and could significantly reduce apoptosis of BEAS-2B cells induced by TGF-ß1(Transforming growth factor ß1) in vitro. In vivo studies demonstrated that HSP70-inducing drugs, such as GGA, attenuated pulmonary fibrosis progression induced by bleomycin (BLM). Collectively, these results suggested that overexpression of HSP70 attenuated pulmonary fibrosis induced by BLM in C57BL/6 mice and EMT process induced by TGF-ß1 through NF-κB/NOX4/ROS pathway in vitro. Thus, HSP70 might be a potential therapeutic strategy for human lung fibrosis.