Leech extract alleviates idiopathic pulmonary fibrosis by TGF-ß1/Smad3 signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Leech, as a traditional Chinese medicine for the treatment of blood circulation and blood stasis, was also widely used to cure pulmonary fibrosis in China. In clinical practice, some traditional Chinese medicine preparation such as Shui Zhi Xuan Bi Hua Xian Tang and Shui Zhi Tong Luo Capsule composed of leech, could improve the clinical symptoms and pulmonary function in patients with idiopathic pulmonary fibrosis (IPF). However, the material basis of the leech in the treatment of IPF were not yet clear. AIM OF THE STUDY: Screen out the components of leech that have the anti-pulmonary fibrosis effects, and further explore the therapeutic mechanism of the active components. MATERIALS AND METHODS: In this study, the different molecular weight components of leech extract samples were prepared using the semi-permeable membranes with different pore sizes. The therapeutic effects of the leech extract groups with molecular weight greater than 10 KDa (>10 KDa group), between 3 KDa and 10 KDa (3-10 KDa group), and less than 3 KDa (<3 KDa group) on pulmonary fibrosis were firstly investigated by cell proliferation and cytotoxicity assay (MTT), cell wound healing assay, immunofluorescence staining (IF) and Western blot (WB) assay through the TGF-ß1-induced fibroblast cell model. Then bleomycin-induced pulmonary fibrosis (BML-induced PF) mouse model was constructed to investigate the pharmacological activities of the active component group of leech extract in vivo. Pathological changes of the mouse lung were observed by hematoxylin-eosin staining (H&E) and Masson's trichrome staining (Masson). The hydroxyproline (HYP) content of lung tissues was quantified by HYP detection kit. The levels of extracellular matrix-related fibronectin (FN) and collagen type Ⅰ (Collagen Ⅰ), pyruvate kinase M2 (PKM2) monomer and Smad7 protein were determined via WB method. PKM2 and Smad7 protein were further characterized by IF assays. RESULTS: Using TGF-ß1-induced HFL1 cell line as a PF cell model, the in vitro results demonstrated that the >10 KDa group could significantly inhibited the cell proliferation and migration, downregulated the expression level of cytoskeletal protein vimentin and α-smooth muscle actin (α-SMA), and reduced the deposition of FN and Collagen Ⅰ. In the BML-induced PF mouse model, the >10 KDa group significantly reduced the content of HYP, downregulated the expression levels of FN and Collagen Ⅰ in lung tissues, and delayed the pathological changes of lung tissue structure. The results of WB and IF assays further indicated that the >10 KDa group could up-regulate the expression level of PKM2 monomer and Smad7 protein in the cellular level, thereby delaying the progression of pulmonary fibrosis. CONCLUSIONS: Our study revealed that the >10 KDa group was the main material basis of the leech extract that inhibited pulmonary fibrosis through TGF-ß1/Smad3 signaling pathway.

Expression of Smad7 inhibits fibrogenic responses of keratocytes to transforming growth factor ß2.

BACKGROUND: Transforming growth factor ß (TGFß) is one of the most important growth factors in the development of fibrosis and scarring on cornea. Smad7, an inhibitory Smad, can inhibit TGFß signal transduction. In recent years, effects of lentiviral-mediated Smad7 on inhibition of fibrosis on some organs have been studied, while little is known about the effects on cornea. This study aimed to determine the effects of lentiviral-mediated Smad7 gene expression on keratocyte proliferation and fibrosis induced by TGF ß2 in vitro. METHODS: Keratocytes were cultured from corneal tissue isolated from Sprague-Dawley (SD) rats and transfected with Smad7 expressing lentiviral vector (Lv-Smad7) or non-functioning control vector (Lv-blank). Following the exposure to TGFß2, keratocytes were processed for immunoblotting to assess the phosphorylation of Smad2 as down-stream event of TGFß/Smad signaling. Expression of fibrotic markers α-smooth muscle actin (α-SMA), type III collagen (collagen III) were measured by Western blotting and quantitative real time polymerase chain reaction (PCR). Overall cell proliferation was determined by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the expression of cell cycle-related marker Ki67 at both mRNA and protein levels. RESULTS: The Smad7 gene transfer suppressed TGFß/Smad signaling in keratocytes by down-regulating phosphorylation of Smad2. Markers of cell proliferation and fibrosis including Ki67, α-SMA, collagen III were inhibited by introduction of Smad 7 into TGFß exposed keratocytes. Consequently, the rate of cell proliferation was attenuated. CONCLUSION: Smad7 gene transfer inhibited fibrogenic responses of keratocytes to TGFß2.

In vivo disruption of TGF-beta signaling by Smad7 in airway epithelium alleviates allergic asthma but aggravates lung carcinogenesis in mouse.

BACKGROUND: TGF-beta has been postulated to play an important role in the maintenance of epithelial homeostasis and the development of epithelium-derived cancers. However, most of previous studies are mainly focused on the function of TGF-beta in immune cells to the development of allergic asthma and how TGF-beta signaling in airway epithelium itself in allergic inflammation is largely unknown. Furthermore, the in vivo TGF-beta function specifically in the airway epithelium during lung cancer development has been largely elusive. METHODOLOGY/PRINCIPAL FINDINGS: To evaluate the in vivo contribution of TGF-beta signaling in lung epithelium to the development of allergic disease and lung cancer, we generated a transgenic mouse model with Smad7, an intracellular inhibitor of TGF-beta signaling, constitutively expressed in mouse airway Clara cells using a mouse CC10 promoter. The mice were subjected to the development of OVA-induced allergic asthma and urethane-induced lung cancer. The Smad7 transgenic animals significantly protected from OVA-induced asthma, with reduced airway inflammation, airway mucus production, extracellular matrix deposition, and production of OVA-specific IgE. Further analysis of cytokine profiles in lung homogenates revealed that the Th2 cytokines including IL-4, IL-5 and IL-13, as well as other cytokines including IL-17, IL-1, IL-6, IP10, G-CSF, and GM-CSF were significantly reduced in the transgenic mice upon OVA induction. In contrast, the Smad7 transgenic animals had an increased incidence of lung carcinogenesis when subjected to urethane treatment. CONCLUSION/SIGNIFICANCE: These studies, therefore, demonstrate for the first time the in vivo function of TGF-beta signaling specifically in airway epithelium during the development of allergic asthma and lung cancer.

[Smad7 instead of Smad6 blocks epithelial-mesenchymal transition induced by TGF-beta in human renal proximal tubule epithelial cells].

AIM: To investigate whether Smad6 and Smad7 can regulate TGF-beta-induced epithelial-mesenchymal transition in human renal proximal tubule epithelial cells. METHODS: Two recombinant adeno-associated viruses (AAV) expressing Smad6 and Smad7 genes were produced without helper virus and then they were delivered into human renal proximal tubule epithelial cells (HKCs). The cells were randomly divided into normal controls, TGF-beta1-treated group, Smad7-infected control, LacZ-infected control, TGF-beta1+Smad7 group or TGF-beta1+Smad6 group, and TGF-beta1 + LacZ group. 10 microg/L of TGF-beta1 was added into the cell culture at the time of 15 min, 30 min, 60 min, and 120 min and the third day. The levels of phospho-Smad2, alpha-smooth muscle actin (alpha-SMA) and E-cadherin proteins were measured by Western blot. The concentration of hydroxyproline excreted into the culture supernatant was determinated by ELISA. The morphological changes of the cells detected by inverted microscope. RESULTS: Compared with the cells in absence of TGF-beta1, the expression level of P-Smad2 in HKCs increased at 15 min, 30 min, 60 min, and 120 min with the TGF-beta1 stimulation. It reached peak at 30 min. TGF-beta1 treatment for 72 hours resulted in significant up-regulation of alpha-SMA protein expression and hydroxyproline secretion, but a marked decrease in E-cadherin expression in the culture of HKCs. 10 microg/L of TGF-beta1 treatment for 72 hours also resulted in marked alteration in cell morphology. The cells lost their regular cuboidal appearance, and become elongated and spindle shaped. In the Smad7-infected cells, the overexpression of Smad7 resulted in a marked decrease of alpha-SMA protein and hydroxyproline synthesis, but a increase of E-cadherin protein, as well as the retainment of epithelial phenotypic appearance. These effects were associated with the inhibition of TGF-induced Smad2 activation, whereas the overexpression of Smad6 had no effect on the TGF-beta-induced changes in HKCs. CONCLUSION: The overexpression of Smad7 instead of Smad6 can efficiently inhibit TGF-beta-induced epithelial-mesenchymal transition by blocking Smad2 activation in human renal proximal tubule epithelial cells.

Activin A as a critical mediator of capillary formation: interaction with the fibroblast growth factor action.

The present study was conducted to elucidate the role of activin A in capillary formation. When bovine aortic endothelial cells (BAEC) were cultured in a collagen gel, basic fibroblast growth factor (FGF-2) induced tube formation. Activin A also induced tube formation and the addition of two factors together was more effective. BAEC produced both FGF-2 and activin A as autocrine factors. Exogenous FGF-2 did not affect the production of activin A but instead upregulated the type II activin receptor. On the other hand, activin A increased the expression of FGF-2 as well as the FGF receptor. Most importantly, when the action of endogenous activin A was blocked by adding follistatin, the tubulogenic action of FGF-2 was nearly completely inhibited. Activin-induced tubulogenesis was markedly inhibited by overexpression of Smad7, an inhibitory Smad. Similarly, an inhibitor of p44/42 mitogen-activated protein (MAP) kinase attenuated the activin-mediated tubulogenesis, whereas an inhibitor of p38 MAP kinase had no effect. These results indicate that FGF-2 and activin A enhance their signals each other in BAEC, and endogenous activin A is critical for FGF-2-induced capillary formation.