Transforming growth factor-β1 involved in urotensin Ⅱ-induced phenotypic differentiation of adventitial fibroblasts from rat aorta

Background Urotensin Ⅱ （UⅡ） is a new vasoconstrictive peptide that may activate the adventitial fibroblasts.Transforming growth factor-β1 （TGF-β1） is an important factor that could induce the phenotypical transdifferentiation of adventitial fibroblasts. This study aimed to explore whether TGF-β1 is involved in UⅡ-induced phenotypic differentiation of adventitial fibroblasts from rat aorta.Methods Adventitial fibroblasts were prepared by the explant culture method. TGF-β1 protein secretion from the cells was determined by enzyme-linked immunosorbent assay （ELISA）. The mRNA and protein expression of α-smooth nuscle actin （α-SM-actin）, the marker of phenotypic differentiation from fibroblasts to myofibroblasts, were determined using real-time quantitative RT-PCR （real-time RT-PCR） and Western blotting, respectively.Results UⅡ stimulated the secretion of TGF-β1 in cultured adventitial fibroblasts in a time-dependent manner. The secretion reached a peak at 24 hours, was higher by 69.8% （P ＜0.01）, than the control group. This effect was also concentration dependent. Maximal stimulation was reached at 10-8 mol/L of UⅡ （P ＜0.01）, which was increased by 59.9%,compared with in the control group （P ＜0.01）. The secretion of TGF-β1 induced by UⅡ was significantly blocked by SB-710411 （10-7 mol/L）, a specific antagonist of UⅡ receptor. In addition, both UⅡ （10-8 mol/L） and TGF-β1 significantly stimulated α-SM-actin mRNA and protein expression. Moreover, the α-SM-actin induced by UⅡ was inhibited by the specific neutralizing antibody （20 μg/ml） of TGF-β1, while the α-SM-actin expression stimulated by TGF-β1 （20 ng/ml）was inhibited by SB-710411 （10-7 mol/L）, the UⅡ receptor antagonist.Conclusion This study suggests that UⅡ could induce TGF-β1 secretion in adventitial fibroblasts via UT activation, and TGF-β1 might be involved in phenotypic differentiation from adventitial fibroblasts into myofibroblasts induced by UⅡ, and TGF-β1 signaling might be one of the important pathways by which UⅡ is involved in vascular fibrosis.

EMT、TGF-β_1、Ang Ⅱ与器官纤维化发生机制的研究进展

纤维化是大多数慢性炎症性疾病的病理转归,几乎能发生在身体的每个组织器官。纤维化以过多的细胞外基质沉积为特征,进一步发展可导致器官功能衰竭乃至死亡。关于器官纤维化的研究很多,但其确切机制目前尚不明确。近年来,上皮间质转化(EMT)、转化生长因子β1(TGF-β1)、血管紧张素Ⅱ(AngⅡ)在组织器官纤维化形成机制研究中备受关注。该文就EMT、TGF-β1、AngⅡ与各器官纤维化的相互关系及作用机制予以综述,以更全面地认识纤维化的发生机制。

Intestinal hormones and growth factors:Effects on the small intestine

There are various hormones and growth factors which may modify the intestinal absorption of nutrients, and which might thereby be useful in a therapeutic setting, such as in persons with short bowel syndrome. In part I, we focus first on insulin-like growth factors, epidermal and transferring growth factors, thyroid hormones and glucocorticosteroids. Part Ⅱ will detail the effects of glucagon-like peptide （GLP）-2 on intestinal absorption and adaptation, and the potential for an additive effect of GLP2 plus steroids.

Influence of baicalin on the expression of receptor activator of nuclear factor-κB ligand and osteoprotegerin in human periodontal ligament cells

Objective To study the effect of baicalin on the expression of receptor activator of nuclear factor-κB ligand(RANKL)and osteoprotegerin(OPG)in cultured human periodontal ligament(HPDL)cells.Methods Small interfering RNA(siRNA)eukaryotic expression vector targeted transforming growth factor βⅡ receptor(TGF-β RⅡ)was constructed and transfected into T cells.HPDL cells with T cells transfected with siRNA or not were placed in the culture medium that had been added with lipopolysaccharide(LPS)and baicalin.The obtained solution was divided into six groups according to the components(group Ⅰ:HPDL cells+LPS+T cells transfected with siRNA1+baicalin;group Ⅱ:HPDL cells+LPS+T cells transfected with siRNA1;group Ⅲ:HPDL cells+LPS+T cells+baicalin;group Ⅳ:HPDL cells+LPS+T cells;group Ⅴ:HPDL cells+baicalin;group Ⅵ:HPDL cells)and was cultured for 48 hours.RT-PCR was used to observe the effect of baicalin on the expression of OPG-RANKL in HPDL cells.Results The ratio of RANKL/OPG in group Ⅰ was lower than that in group Ⅱ(P<0.01)and higher than that in group Ⅲ(P<0.01);The ratio of RANKL/OPG in group Ⅲ was lower than that in group Ⅳ(P<0.01);the ratio of RANKL/OPG in group Ⅳ was higher than that in group Ⅵ(P<0.01);the ratio of RANKL/OPG in group Ⅴ was lower than that in group Ⅵ(P<0.05).Conclusion ① Baicalin could decrease the ratio of RANKL/OPG in HPDL cells.② The TGF-β signaling transduction plays an important role in the effect of baicalin on the RANKL/OPG ratio in HPDL cells.③ Baicalin acts not only through TGF-β to regulate RANKL/OPG in HPDL cells,but also through other pathways.

Differential Mechanisms of the Effect of Peroxisome Proliferator-Activated Receptor Gamma Agonists on Bleomycin-Induced Lung Fibrosis

Background and Objectives: Peroxisome proliferator-activated receptor-g (PPAR-g) is a nuclear receptor whose activation regulates inflammation and fibrosis in various organs. We aimed to investigate the effect of two PPAR-g ligands, telmisartan and rosiglitazone, on lung injury and fibrosis induced by intratracheal bleomycin (BLM). Methods: Lung injury and fibrosis was induced in female C57Bl/6 mice by intratracheal instillation of 1.0 mg/kg of BLM. Some of the animals received rosiglitazone intraperitoneally or telmisartan in drinking water. Bronchoalveolar lavage (BAL) was performed 2, 7, 14 or 21 days after BLM instillation for cell counting and measurement of mediators in the lung. In a separate series, the lungs were sampled for collagen assay and histopathological evaluation. Results: Treatment with rosiglitazone or telmisartan significantly attenuated the BLM-induced increases in lung collagen content, pathological score, and inflammatory cells in BAL fluid. Rosiglitazone significantly suppressed BLM-induced elevation of TGF-b1, MCP-1, and IL-6 levels in the lung. In contrast, telmisartan made no changes in these cytokines, whereas it mitigated the BLM-induced increase in prostaglandin F2a in the lung. Higher concentrations of rosiglitazone and telmisartan attenuated proliferation of lung fibroblasts in vitro. Conclusions: Two PPAR-g ligands, rosiglitazone and telmisartan, exert protective effects on BLM-induced lung fibrosis through the suppression of different profibrotic mediators.

TGF-β stimulation of EMT programs elicits non-genomic ER-α activity and anti-estrogen resistance in breast cancer cells

Aim:Estrogen receptor-α(ER-α)activation drives the progression of luminal breast cancers.Signaling by transforming growth factor-β(TGF-β)typically opposes the actions of ER-α;it also induces epithelial-mesenchymal transition(EMT)programs that promote breast cancer dissemination,stemness and chemoresistance.The impact of EMT programs on nongenomic ER-αsignaling remains unknown and was studied herein.Methods:MCF-7 and BT474 cells were stimulated with TGF-βto induce EMT programs,at which point ER-αexpression,localization,and nongenomic interactions with receptor tyrosine kinases and MAP kinases(MAPKs)were determined.Cell sensitivity to anti-estrogens both before and after traversing the EMT program was also investigated.Results:TGF-β-stimulated MCF-7 and BT474 cells to acquire EMT phenotypes,which enhanced cytoplasmic accumulation of ER-αwithout altering its expression.Post-EMT cells exhibited:(1)elevated expression of EGFR and IGF1R,which together with Src formed cytoplasmic complexes with ER-α;(2)enhanced coupling of EGF,IGF-1 and estrogen to the activation of MAPKs;and(3)reduced sensitivity to tamoxifen,an event reversed by administration of small molecule inhibitors against the receptors for TGF-β,EGF,and IGF-1,as well as those against MAPKs.Conclusion:EMT stimulated by TGF-βpromotes anti-estrogen resistance by activating EGFR-,IGF1R-,and MAPK-dependent nongenomic ER-αsignaling.