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Abstract Chronic pancreatitis is characterized by pancreatic fibrosis, associated with excessive activation of pancreatic stellate cells (PSCs) and increased expression of transforming growth factor-β1 (TGF-β1). Recently, our studies have shown that autophagy inhibitor could inhibit PSCs activation and reduce collagen secretion. Saikosaponin d (SSd), the major active component of bupleurum falcatum (a medicinal plant), has anti-fibrosis effects in liver. However, it is unclear whether SSd has a role in pancreatic fibrosis. This study aimed to investigate the effect of SSd on the autophagy and activation of PSCs in vivo and in vitro. In vivo, a rat chronic pancreatitis model was induced by intravenous injection of dibutyltin dichloride. SSd was administered at a dose of 2.0 mg/kg body weight per day by gavage. After 4 weeks, the pancreas was collected for histological and molecular analysis. In vitro, PSCs were isolated and cultured for treatment with different dosages of SSd. The results showed that SSd inhibited PSCs autophagy and activation while also reducing extracellular matrix (ECM) formation and pancreatic damage. SSd inhibited autophagy through activating the PI3K/Akt/mTOR pathway. SSd also promoted degradation of ECM with an increasing ratio of MMPs/TIMPs and suppressed the TGF-β1/Smads pathway. From these results, we concluded that SSd prevents pancreatic fibrosis by reducing autophagy of PSCs through PI3K/Akt/mTOR pathway, which has crosstalk with the TGF-β1/Smads pathway. Highlights • Saikosaponin d improved pancreatic damage induced by DBTC in rat model. • Saikosaponin d inhibited PSCs activation and ECM formation in pancreas. • Saikosaponin d inhibited PSCs activation through reducing autophagy of PSCs. • Saikosaponin d repressed autophagy through activating the PI3K/Akt/mTOR signalling pathway in PSCs. [ABSTRACT FROM AUTHOR]

Aims Autophagy is an intracellular metabolic process that degrades and recycles own constituents to maintain homeostasis and supply substrates. Disruption of collagen degradation is one of the pathogenesis of pancreatic fibrosis. In this study, we investigated the effects of inhibiting autophagy on the collagen degradation of PSCs. Main methods Rats were injected dibutyltin dichloride (DBTC) to induce chronic pancreatitis (CP) model. The expression of LC3B was measured by western blotting. Rat PSCs were isolated from pancreas tissues, and the experiments used the primary PSCs. Autophagosome was confirmed by transmission electron microscope. Immunofluorescence for LC3B and α-SMA were applied to assess autophagy and activated PSCs. The effects of autophagy inhibition of 3-MA on the expressions of LC3B, Atg5, and Beclin-1 were investigated by real-time PCR and Western blotting, as well as the α-SMA, TGF-β1, ColI, Col III, FN, MMP-2, MMP-13, TIMP-1 and TIMP-2. Meanwhile, the secretion of ColI, Col III and FN were investigated by ELISA. Key findings The LC3-II/I ratio was increased in rat CP model. Autophagosomes and an increased autophagic level were observed during PSCs activation. Inhibiting autophagy could down-regulate the expressions of α-SMA, TGF-β1, FN, ColI, Col III, TIMP-1 and TIMP-2, while the expressions of MMP-2 and MMP-13 were increased. Significance This study confirmed that autophagic level is increased during PSCs activation in vivo and in vitro. Inhibiting autophagy prevents the activation of PSCs, and suppresses fibrosis through promoting extracellular matrix (ECM) degradation by decreasing the expression of TGF-β1 and increasing MMPs/TIMPs ratio. [ABSTRACT FROM AUTHOR]

Background: Autophagy is of importance in the regulation of cell differentiation and senescence in podocytes. It is possible that derangement of autophagy under different pathological conditions activates or enhances Epithelial-to-Mesenchymal Transition (EMT) in podocytes, resulting in glomerular sclerosis. To test this hypothesis, the present study produced lysosome dysfunction by inhibition of the vacuolar H+-ATPase (V-ATPase) to test whether deficiency of autophagic flux leads to enhancement of EMT in podocytes. Methods and Results: By Western blot and confocal analysis, lysosome inhibition using a V-ATPase inhibitor or its siRNA was found to markedly decreases the epithelial markers (P-cadherin and ZO-1) and increases the mesenchymal markers (FSP-1 and α-SMA). This enhancement was accompanied by deficient autophagic flux, as demonstrated by marked increases in LC3B-II and p62/Sequestosome 1. However, inhibition of autophagosome formation using spaudin-1 significantly attenuated both enhancement of EMT and deficiency of autophagic flux. To explore the mechanisms by which deficient autophagic flux enhances EMT, we tested the role of accumulated p62 as a signal hub in this process. Neither the nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear kappa-light-chain-enhancer pathways of p62 contributed to enhanced EMT. However, inhibition of cyclin-dependent kinase 1 (CDK1) activity reduced the phosphorylation of p62 and enhanced EMT in podocytes similar to lysosome dysfunction. Conclusion: The lack of phosphorylated p62 leads to a faster exit from cell mitosis, enhanced EMT associated with lysosome dysfunction may be attributed to accumulation of p62 and associated reduction of p62 phosphorylation. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]