Increased transforming growth factor beta 1 expression mediates ozone-induced airway fibrosis in mice

Ozone (O₃), a commonly encountered environmental pollutant, has been shown to induce pulmonary fibrosis in different animal models; the underlying mechanism, however, remains elusive. To investigate the molecular mechanism underlying O₃-induced pulmonary fibrosis, 6- to 8-week-old C57BL/6 male mice were exposed to a cyclic O₃ exposure protocol consisting of 2 days of filtered air and 5 days of O₃ exposure (0.5?ppm, 8?h/day) for 5 and 10 cycles with or without intraperitoneal injection of IN-1233, a specific inhibitor of the type 1 receptor of transforming growth factor beta (TGF-β), the most potent profibrogenic cytokine. The results showed that O₃ exposure for 5 or 10 cycles increased the TGF-β protein level in the epithelial lining fluid (ELF), associated with an increase in the expression of plasminogen activator inhibitor 1 (PAI-1), a TGF-β-responsive gene that plays a critical role in the development of fibrosis under various pathological conditions. Cyclic O₃ exposure also increased the deposition of collagens and alpha smooth muscle actin (α-SMA) in airway walls. However, these fibrotic changes were not overt until after 10 cycles of O₃ exposure. Importantly, blockage of the TGF-β signaling pathway with IN-1233 suppressed O₃-induced Smad2/3 phosphorylation, PAI-1 expression, as well as collagens and α-SMA deposition in the lung. Our data demonstrate for the first time that O₃ exposure increases TGF-β expression and activates TGF-β signaling pathways, which mediates O₃-induced lung fibrotic responses in vivo.     

The immunopharmacological properties of transforming growth factor beta

Transforming growth factor-beta (TGF-beta) family members are multifunctional molecules, which play pivotal roles in regulating cell proliferation, differentiation, migration, development, tissue remodeling and repair. These events are closely associated with host immune responses and inflammation. Despite some controversies on their function in controlling dendritic and T regulatory cell development and activity, the importance of TGF-betas in the progress of autoimmunity and inflammatory diseases has been well appreciated and new aspects of their contribution continue to be recognized. Since one of the major biological properties of TGF-betas is its capacity to potently suppress immune responses, they are considered as candidates for the development of therapeutic agents to fend off undesirable damage associated with immune and inflammatory conditions.     

幽门螺杆菌感染与胃黏膜上皮细胞转化生长因子β1表达的关系

目的为证实幽门螺杆菌(H.pylori)通过诱导胃黏膜上皮细胞表达转化生长因子β1(TGF-β1)抑制机体免疫功能,参与H.pylori免疫逃逸提供依据。方法选用1.0×109CFU/ml(低浓度),4.0×109CFU/ml(中浓度),8.0×109CFU/ml(高浓度)H.pylori国际标准毒力菌株NCTC11637菌悬液分别感染体外培养胃黏膜上皮细胞,建立不同共孵育时间(0、0.5、1、1.5、2、4、8、12h)H.pylori体外感染细胞模型,以不加H.pylori的胃黏膜上皮细胞为对照组,用酶联免疫吸附试验(ELISA)法测定感染细胞培养上清TGF-β1含量;以4.0×109CFU/ml灭活菌株菌悬液与胃黏膜上皮细胞共孵育,同法检测感染细胞2、12h培养上清TGF-β1含量。结果不同浓度时间组H.pylori诱导产生TGF-β1的量均较对照组显著增高(P<0.01);各浓度时间组TGF-β1分泌有相似的动态趋势,但尤以中浓度组表达量最高;H.pylori灭活菌株与活菌诱导TGF-β1的表达差异无统计学意义(P>0.05)。结论H.py-lori可能具有诱导胃黏膜上皮细胞分泌TGF-β1的菌体成分,当H.pylori感染人胃黏膜细胞后,其菌体成分通过诱导胃黏膜细胞TGF-β1的表达,抑制机体免疫功能,导致H.pylori免疫逃逸,参与其H.pylori致病过程。     

Modulation of the activity of transforming growth factor beta

The recent patent literature on the modulation of the activity of transforming growth factor beta (TGF-β) is reviewed and placed in context of the properties and biological activities of the TGF-β isoforms. The role of TGF-β in acceleration of wound healing and its role in the development of fibrotic disease makes it an attractive target for both agonists and antagonists. Intervention has been proposed both directly, by binding to the TGF-β molecule itself, and indirectly, by modulating both its synthesis and signalling pathways. Most proof-of-principle studies and patent applications on therapeutic intervention have used antibodies to TGF-β or naturally occurring TGF-β binding molecules. However, there have been several applications on the use of small molecules to intervene at other points in the TGF-β signalling pathway.     

Aerosolized adrenomedullin suppresses pulmonary transforming growth factor-beta1 and interleukin-1 beta gene expression in vivo

The effect of aerosolized adrenomedullin on interleukin-1 beta and transforming growth factor (TGF)-beta1 mRNA and protein expression was studied in surfactant depleted piglets, receiving aerosolized adrenomedullin (adrenomedullin, n=6), aerosolized adrenomedullin plus i.v. N(G)-nitro-L-arginine-methylester (adrenomedullin+L-NAME, n=5), or aerosolized saline solution (control, n=6). After 8 h of aerosol interval therapy, mRNA expression of interleukin-1 beta and TGF-beta1 in lung tissue was quantified normalized to beta-actin and hypoxanthine-guanine-phosphoribosyl-transferase by real-time polymerase chain reaction (PCR). Interleukin-1 beta and TGF-beta1 protein concentration in lung tissue was quantified by enzyme-linked immunosorbent assay (ELISA). In the adrenomedullin group, interleukin-1 beta and TGF-beta1 mRNA expression was lower than in controls. Reduction for interleukin-1 beta/beta-actin was 56% (p<0.001), for interleukin-1 beta/hypoxanthine-guanine-phosphoribosyl-transferase 60% (p<0.001), for TGF-beta1/beta-actin 65.5% (p<0.001), and for TGF-beta1/hypoxanthine-guanine-phosphoribosyl-transferase 56.2% (p<0.001). Mean interleukin-1 beta protein expression was different between the groups, p<0.05 (adrenomedullin 601+/-61, Control 836+/-88 pg/mg protein). L-NAME did not antagonize adrenomedullin effect on TGF-beta1 mRNA. In conclusion, aerosolized adrenomedullin reduced pulmonary inflammatory and pro-fibrotic response.     

Foxp3和转化生长因子-β在实验性关节炎大鼠中表达的研究

目的探讨CD4+CD25+调节性T细胞在实验性关节炎中的作用及其机制。方法①将大鼠随机分为模型组和对照组,根据文献建立模型,在建模成功后的不同时间点取脾脏关节滑膜。②采取反转录-聚合酶链反应(RT-PCR)的方法检测大鼠脾脏Foxp3 mRNA的表达,采取免疫组织化学半定量法检测脾脏和滑膜转化生长因子(TGF)-β1的表达。结果①Foxp3 mRNA在实验性关节炎大鼠脾脏中的动态表达过程在关节炎急性期表达最高,慢性期逐渐下降,均高于对照组(P<0.01)。②TGF-β1在实验性关节炎大鼠脾脏中的动态表达过程为逐渐增高,到关节炎急性期时,表达降低,慢性期升高,均高于对照组(P<0.01)。③实验性关节炎大鼠脾脏Foxp3 mRNA的表达与TGF-β1的表达呈线性负相关(r=0.8124)。④实验性关节炎大鼠关节滑膜TGF-β1的动态表达过程为逐渐增高,到慢性期下降,均高于对照组(P<0.01)。⑤TGF-β1在实验性关节炎大鼠滑膜中的表达与关节的严重程度有相关关系(与关节炎病理评分的r=0.9474)。结论①在实验性关节炎大鼠中,CD4+CD25+调节性T细胞的增减与炎症反应的强弱呈正相关,可能因其功能存在缺陷,不能有效抑制机体的自身免疫反应。②抑制性因子TGF-β1产生相对不足并且分泌延迟可能是造成实验性关节炎大鼠脾脏CD4+CD25+调节性T细胞功能缺陷的原因之一。③在实验性关节炎大鼠中Foxp3表达基因是否存在缺陷,有待进一步研究证实。     

Physiological concentrations of transforming growth factor beta1 selectively inhibit human dendritic cell function

In this study the effects of different in vitro conditioning with transforming growth factor (TGF) beta1 on human monocyte-derived DC maturation (hMo-DC) were investigated. hMo-DC differentiated in the presence of physiologically relevant concentrations of TGFbeta1 (2 ng/ml) failed to undergo complete maturation despite adequate stimulation with LPS or LPS+IFNgamma.These hMo-DC did not produce IL-12p70 or PGE2, and showed decreased IL-10 and IL-18 production and HLA-DR expression. However, the expression of these molecules, except for IL-12p70, was not significantly affected in hMo-DC differentiated in the presence of lower concentrations of TGFbeta1 (0.2 and 0.02 ng/ml). Exposure of hMo-DC to TGFbeta1 (2 ng/ml) after they had completed differentiation had minimal effects. Thus, the functional response of hMo-DC to LPS or LPS+IFNgamma depended on the stage of hMo-DC differentiation at which cells were first exposed to TGFbeta1 and on the concentration of TGFbeta1. These results suggest that in the in vivo micro-environment, the concentrations and the timing of monocyte exposure to TGFbeta1 may be crucial in the differentiation of DC toward more or less mature phenotypes, and this may have important implications for DC functions. The decrease in T-cell proliferation and a small increase in IL-5 production by T cells co-cultured with hMo-DC that had been treated with TGFbeta1, suggest the possibility that in vivo such DC may provide chronic, but incomplete signals to T cells, and this could be a potential mechanism underlying polarisation of T cells towards anergy.     

Feitai, a Chinese herbal medicine, reduces transforming growth factor-beta1 and monocyte chemoattractant protein-1 expression in bleomycin-induced lung fibrosis in mice

Feitai, a Chinese medicine formulation, has been shown to protect against lung fibrosis induced by bleomycin (BLM). In the present study, we investigated the effect of Feitai on transforming growth factor (TGF)-beta1 and monocyte chemoattractant protein-1 (MCP-1), which play important roles in the pathogenesis of BLM-induced lung fibrosis. The results demonstrated that Feitai could significantly attenuate BLM-induced acute lung inflammation and subsequent lung fibrosis. Meanwhile, the expression of MCP-1 and TGF-beta1 mRNA in the lungs increased in the BLM-treated group compared with the saline-instilled control group and Feitai treatment significantly decreased cytokine expression in BLM-treated mice. In addition, Feitai diminished the accumulation of MCP-1- and TGF-beta1-positive cells in lung tissues at the time of peak mRNA levels. In summary, the results of the present study indicate that treatment with Feitai ameliorates BLM-induced lung fibrosis, at least in part via the inhibition of MCP-1 and TGF-beta1 expression.     

Modulation of urokinase-type plasminogen activator by transforming growth factor beta1 in acetaldehyde-activated hepatic stellate cells

The aim of this study was to determine whether transforming growth factor-beta1 (TGF-beta1) induces the synthesis, release and gene expression of urokinase-type plasminogen activator (uPA) in hepatic stellate cells. In addition to stimulating collagen production, TGF-beta1 induced the morphological and phenotypical changes characteristic of hepatic stellate cell activation. However, these changes accentuated in cells previously activated with acetaldehyde. TGF-beta1 increased to 2-fold uPA activity in lysates from quiescent cells, and to 3.5-fold in activated cells, and induced uPA gene expression to the same extent in both activated and non-activated cells. TGF-beta1 had a modest stimulatory action on the release of uPA into the conditioned medium, but reduced acetaldehyde-induced release, as demonstrated by Western blot analysis. In accord, whereas TGF-beta1 produces no effect on uPA activity in the conditioned media from quiescent cells, it significantly reduces the stimulatory action of acetaldehyde. These results show that the activity and gene expression of uPA are regulated by both acetaldehyde and TGF-beta1 and that the proteolytic activity in the extracellular space is reduced by the influence of TGF-beta1. Further studies on the molecular mechanisms responsible for the regulation of the plasminogen system by TGF-beta1 and other molecules in the presence of acetaldehyde will contribute to a better understanding of the processes involved in fibrogenesis.     

Inhibition of transforming growth factor beta signaling reduces pancreatic adenocarcinoma growth and invasiveness

Transforming growth factor beta (TGFbeta) is a pleiotropic factor that regulates cell proliferation, angiogenesis, metastasis, and immune suppression. Dysregulation of the TGFbeta pathway in tumor cells often leads to resistance to the antiproliferative effects of TGFbeta while supporting other cellular processes that promote tumor invasiveness and growth. In the present study, SD-208, a 2,4-disubstituted pteridine, ATP-competitive inhibitor of the TGFbeta receptor I kinase (TGFbetaRI), was used to inhibit cellular activities and tumor progression of PANC-1, a human pancreatic tumor line. SD-208 blocked TGFbeta-dependent Smad2 phosphorylation and expression of TGFbeta-inducible proteins in cell culture. cDNA microarray analysis and functional gene clustering identified groups of TGFbeta-regulated genes involved in metastasis, angiogenesis, cell proliferation, survival, and apoptosis. These gene responses were inhibited by SD-208. Using a Boyden chamber motility assay, we demonstrated that SD-208 inhibited TGFbeta-stimulated invasion in vitro. An orthotopic xenograft mouse model revealed that SD-208 reduced primary tumor growth and decreased the incidence of metastasis in vivo. Our findings suggest mechanisms through which TGFbeta signaling may promote tumor progression in pancreatic adenocarcinoma. Moreover, they suggest that inhibition of TGFbetaRI with a small-molecule inhibitor may be effective as a therapeutic approach to treat human pancreatic cancer.     

转化生长因子β1在肾间质纤维化大鼠模型中的表达及意义

目的了解转化生长因子-β1(transforming growth factor-β1,TGF-β1)在肾小管间质纤维化中的表达及其意义;探讨及比较科素亚及霉酚酸酯的肾脏保护作用及可能的作用机制。方法采用单侧输尿管结扎术(unilateral ureteral obstruction,UUO)建立肾小管间质纤维化大鼠模型。将大鼠随机分为4组:假手术组、模型组、科素亚治疗组[30mg/(kg.d)]、霉酚酸酯治疗组[20mg/(kg.d)]。手术后第9天处死各组大鼠,分别经免疫组化方法观察各组大鼠肾组织的TGF-β1的表达部位、表达水平及α-平滑肌肌动蛋白(α-smooth muscle actin,α-SMA)的表达情况;HE及Masson染色评定各组肾小管间质损害程度。结果模型组TGF-β1、α-SMA的表达及肾小管间质损伤指数明显高于假手术组(P<0.05);而科素亚治疗组、霉酚酸酯治疗组均明显低于模型组(P<0.05);科素亚治疗组与霉酚酸酯治疗组相比,各项指标差异均无统计学意义(P>0.05);TGF-β1与肾小管间质损伤指数(r=0.788,P<0.01)及α-SMA(r=0.940,P<0.01)呈正相关。结论TGF-β1在肾小管间质纤维化的病程进展中起重要的促进作用。而科素亚、霉酚酸酯则可能通过下调TGF-β1的表达而达到防治肾小管间质纤维化的作用。     

白花丹醌对瘦素刺激人肝星状细胞转化生长因子-β_1表达的影响

目的研究白花丹醌对瘦素刺激体外培养人HSC-LX2TGF-β1 mRNA和蛋白表达的影响。方法体外培养HSC-LX2,瘦素(leptin)刺激24h,各药物与细胞共孵育24h后,采用荧光PCR检测各组TGF-β1 mRNA的表达和免疫组织化学方法检测TGF-β1蛋白表达情况。结果与leptin组比较,白花丹醌各剂量组作用24h后,HSC-LX2细胞中TGF-β1 mRNA的水平明显降低,尤以中、高剂量组明显(P<0.01);免疫组化结果显示白花丹醌各剂量组对HSC-LX2细胞TGF-β1蛋白表达有一定的抑制作用,且作用呈剂量依赖性。结论白花丹醌抗肝纤维化作用机制之一是从mRNA和蛋白水平抑制TGF-β1表达,从而抑制HSCECM的合成,发挥抗肝纤维化作用。     

Growth factors and bone formation in osteoporosis: roles for fibroblast growth factor and transforming growth factor beta

Osteoporosis is characterised by excess bone fragility resulting from bone loss and altered bone microarchitecture. Bone loss occurring during aging and after menopause in women is known to result from an imbalance between bone formation and resorption. Bone formation is dependent on the commitment of osteoprogenitor cells, the proliferation of pre-osteoblasts, their differentiation into mature osteoblasts synthesising bone matrix and the life-span of mature osteoblasts. Transforming Growth Factor beta (TGFbeta) and Fibroblast Growth Factors (FGFs) are important factors that promote osteoprogenitor cell proliferation and osteogenesis. Reduced expression of TGFbeta in bone was found in several animal models of osteopenia. In addition, both FGF and TGFbeta were found to exert anabolic effects on bone formation in intact animals and to reduce bone loss in experimental models of osteoporosis. Both genetic manipulation of FGF and TGFbeta or their receptors in mice and bone phenotype associated with FGF receptors and TGFbeta mutations or polymorphism suggest that TGFbeta and FGF signalling may contribute to the control of osteogenesis and bone mass in vivo. The determination of molecular mechanisms involved in the anabolic actions of FGF and TGFbeta in cells of the osteoblastic lineage may lead in the future to the development of new therapeutic strategies aimed at improving bone formation in osteoporotic patients.     

缬沙坦对糖尿病肾病患者血清转化生长因子TGF-β1水平的影响临床观察

目的 探讨缬沙坦对糖尿病肾病患者血清转化生长因子β1（TGF-β1）水平的临床观察。方法 选郑州大学第一附属医院收治216例糖尿病肾病患者作为观察对象,分为110例对照组和106例实验组,用酶联免疫吸附法测定血清TGF-β1水平,并进行组间比较。结果 对照组治疗前后的TGF-β1含量虽有所下降,但无统计学意义,P〉0.05,而实验组在治疗前后的TGF-β1含量有统计学意义,P〈0.05,治疗后的对照组和实验组的TGF-β1含量也有统计学差异,P〈0.05。结论 缬沙坦能抑制TGF-β1的含量,能有效的减缓或控制慢性肾损害,使其在糖尿病肾病中减缓肾小球硬化及肾间质纤维化发挥重要意义。     

Involvement of haemoxygenase-1 in ozone-induced airway inflammation and hyperresponsiveness

Haemoxygenase catalyses the degradation of haem to bilirubin, and the inducible form of haemoxygenase, haemoxygenase-1, is highly induced in response to oxidative stress in vitro. The effect of haemoxygenase-1 in oxidant stress in vivo is not known. We determined the effect of exposure to ozone on haemoxygenase-1 expression, and the modulation of haemoxygenase-1 expression on ozone-induced lung neutrophilia and bronchial hyperresponsiveness in rats. Ozone caused a significant induction of lung haemoxygenase-1. Pretreatment of rats with haemoglobin, a potent inducer of haemoxygenase-1, resulted in a large induction of haemoxygenase-1 expression, and inhibited ozone-induced neutrophilia and bronchial hyperresponsiveness. Tin protoporphyrin, a competitive inhibitor of haemoxygenase, reduced the expression of haemoxygenase-1 induced by haemoglobin. It enhanced ozone-induced neutrophilia, but not the bronchial hyperresponsiveness, and reduced the protective effect of haemoglobin. Overall, there was an association between bronchial hyperresponsiveness and the neutrophilic response. These data indicate that haemoxygenase-1 plays an important role in modulating the effects of an oxidant, such as ozone in the lungs.     

Low doses of 2,3,7,8-tetrachlorodibenzo- p-dioxin increase transforming growth factor beta and cause myocardial fibrosis in marmosets ( Callithrix jacchus)

Epidemiological studies have suggested an association between exposure to dioxins and cardiovascular morbidity and mortality. However, cardiotoxic effects of low doses of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) in animals have not been reported so far. We studied the hearts of male marmosets ( Callithrix jacchus)after treatment with single subcutaneous doses of 1, 10 or 100 ng TCDD/kg body weight or vehicle (toluene/DMSO 1+2 v/v, 100 microl/kg body weight). The animals were killed 2 or 4 weeks after treatment. Tissue samples of left ventricular myocardium were stained with picrosirius red and examined histologically along with quantitative image analysis. Extracellular matrix proteins were additionally analysed by western blotting. Monkeys showed no overt signs of toxicity nor did their relative heart weights differ significantly depending on treatment. Histology revealed an increase of picrosirius red-positive area above control values in 2 of 4 (1 ng TCDD/kg body weight), 6 of 12 (10 ng/kg) and 6 of 10 (100 ng/kg) marmosets. Western blotting confirmed these histological findings showing an increase of collagen, fibronectin and laminin in the hearts of TCDD-treated animals. Western blotting additionally showed an increased concentration of transforming growth factor beta1 (TGF-beta1) as well as TGF-beta receptor type I which could be a functional link to the effects on extracellular matrix. Our findings might explain the association of TCDD exposure with increased cardiovascular mortality observed in epidemiological studies and should stimulate further research on the role of changes in the extracellular matrix in the toxic effects of dioxins and related substances on other organs.     

Decreased airway expression of vascular endothelial growth factor in cigarette smoke-induced emphysema in mice and COPD patients

Vascular endothelial growth factor (VEGF) signaling is crucial for lung structure maintenance. Although VEGF deficiency plays a role in the pathogenesis of emphysema in animals, little is known about VEGF expression levels and functions, as well as VEGF receptors, in airway epithelial cells, which are in direct contact with the environment. In this study, C57BL/6J mice were exposed to cigarette smoke (CS) for short (approximately 10 days) and long (4-24 wk) time periods, and bronchiolar expressions of VEGF and its receptors VEGFR-1 and VEGFR-2 were examined. The relationships between the expressions of VEGF, VEGFR-1, and VEGFR-2 and smoking histories and/or chronic obstructive pulmonary disease (COPD) were examined in humans. The mRNA levels were quantified in bronchiolar epithelium harvested by laser capture microdissection in both mouse and human lung tissues or in human bronchial epithelium harvested by bronchoscopic brushing. The VEGF protein level was assessed by immunohistochemistry or enzyme-linked immunosorbent assay. Repeated CS exposure downregulated bronchiolar expressions of VEGF and both VEGF receptors at various time points prior to the development of emphysema. In humans, bronchiolar VEGF was significantly decreased in smokers with COPD compared to lifelong nonsmokers, as well as to smokers without COPD; however, there was no difference in bronchiolar VEGF levels between lifelong nonsmokers and smokers without COPD. On the other hand, bronchiolar VEGFR-2 was downregulated in smokers with and without COPD compared to lifelong nonsmokers. These findings suggest the association of downregulation of bronchiolar VEGF and its receptors with cigarette smoking and COPD.