Transforming growth factor-beta promotes fibroblast apoptosis induced by H2O2

Transforming growth factor-beta (TGF-beta) is believed to play a central role in fibroblastic wound repair and subsequent scar formation. Fibroblasts undergo apoptosis as granulation tissue evolves into a scar. To determine whether TGF-beta influences fibroblast apoptosis, human lung fibroblasts (IMR-90) were treated with TGF-beta (2 to 10 ng/mL) and then exposed to H(2)O(2) (50 to 150 microM), an inducer of fibroblast apoptosis. Apoptosis was evaluated by nuclear staining with Hoechst33342 and terminal deoxynucleotidyl transferase (TdT)-mediated nucleotide nick-end labeling. TGF-beta alone did not induce fibroblast apoptosis, but it dose-dependently augmented the apoptosis induced by exposure to H(2)O(2). TGF-beta also increased the intracellular level of peroxides measured with carboxydichlorodihydrofluorescein, but it did not affect the protein levels of Bcl-2, Bax, Bad, or p53 proteins. These results suggest that TGF-beta promotes lung fibroblast apoptosis induced by H(2)O(2), probably by increasing intracellular peroxides. Thus, TGF-beta may promote the elimination of fibroblasts from wounds, particularly under conditions of exposure to enhanced oxidative stress in the lung.     

转化生长因子β和肺纤维化

转化生长因子β(transforming growth factor-β,TGF-β)是启动和终止炎症和组织修复的调节因子,是参与调控肺纤维化发生的细胞因子.TGF-β亚单位功能与其种类以及与受体的亲和力有密切关系.TGF-β的信号通路在纤维化的发生发展中起重要作用.     

Transforming growth factor-beta3 stimulates lactotrope cell growth by increasing basic fibroblast growth factor from folliculo-stellate cells

Recently, we have shown that transforming growth factor-beta3 (TGFbeta3) mediates estradiol's mitogenic action in primary cultures of mixed anterior pituitary cells. In some cell types, TGFbeta isoforms stimulate cell proliferation via a paracrine mechanism by increasing growth stimulatory peptide growth factors. Whether such a mechanism exists in pituitary cell culture was examined in the studies presented here. The data demonstrate that unlike the response of lactotropes in mixed pituitary cultures, cultures of enriched lactotropes, obtained by Percoll gradient separation, did not proliferate in response to TGFbeta3 treatment. The lactotropic cells of the RC-4B/C cell line, a cell line that contains all of the hormone-secreting cell types of the anterior pituitary but is devoid of folliculo-stellate (FS) cells, did not proliferate in response to TGFbeta3 unless RC-4B/C cells were cocultured with FS cells. Enriched lactotropes cocultured with FS cells also demonstrated a proliferative response to TGFbeta3. Media collected from FS cells treated with TGFbeta3 stimulated the proliferation of lactotropes in enriched cultures. TGFbeta3 increased the release of basic fibroblast growth factor from FS cells. Immunoneutralization of basic fibroblast growth factor in FS cell-conditioned medium inhibited the growth stimulatory action on lactotropes. These data provide evidence for a novel mechanism of TGFbeta3 action involving cell-to-cell interaction in the anterior pituitary between lactotropes and FS cells during estrogen-induced mitogenesis.     

Transforming growth factor-beta3 increases gap-junctional communication among folliculostellate cells to release basic fibroblast growth factor

Folliculostellate (FS) cells are known to communicate with each other and with endocrine cells via gap junctions in the anterior pituitary. We investigated whether TGFbeta3 and estradiol, known to regulate FS cell production and secretion of basic fibroblast growth factor (bFGF), increases gap junctional communication to alter bFGF secretion from FS cells. FS cells in monolayer cultures were treated with TGFbeta3 or vehicle alone for 24 h and then microinjected with Lucifer Yellow and high-molecular-weight Texas Red dextran. Ten minutes later the transfer of dye among adjacent cells was recorded with a digital microscope. TGFbeta3 increased the transfer of dye. The TGFbeta3-neutralizing antibody and the gap junction inhibitor octanol reduced the effect of TGFbeta3 on the transfer of dye. The TGFbeta3-induced transfer of dye was unaltered by simultaneous treatment with estradiol. The steroid alone also had no effect. TGFbeta3 increased total and phosphorylated levels of connexin 43. Estradiol treatment did not produce any significant changes on basal or TGFbeta3-induced increases in connexin 43 levels. The gap-junction inhibitor octanol reduced TGFbeta3-increased levels of bFGF in FS cells. Taken together, these results suggest that TGFbeta3 may act on FS cells to increase gap-junctional communication to maximize its effect on bFGF secretion.     

Transforming growth factor-beta signaling and ubiquitinators in cancer

Transforming growth factor-beta (TGF-beta) represents a large family of growth and differentiation factors that mobilize complex signaling networks to regulate cellular differentiation, proliferation, motility, adhesion, and apoptosis. TGF-beta signaling is tightly regulated by multiple complex mechanisms, and its deregulation plays a key role in the progression of many forms of cancer. Upon ligand binding, TGF-beta signals are transduced by Smad proteins, which in turn are tightly dependent on modulation by adaptor proteins such as embryonic liver fodrin, Smad anchor for receptor activation, filamin, and crkl. A further layer of regulation is imposed by ubiquitin-mediated targeting and proteasomal degradation of specific components of the TGF-beta signaling pathway. This review focuses on the ubiquitinators that regulate TGF-beta signaling and the association of these ubiquitin ligases with various forms of cancer. Delineating the role of ubiquitinators in the TGF-beta signaling pathway could yield powerful novel therapeutic targets for designing new cancer treatments.     

Transforming growth factor-beta and its role in asthma

Transforming growth factor-beta (TGF-beta) is an important fibrogenic and immunomodulatory factor that may play a role in the structural changes observed in the asthmatic airways. In vitro as well as in vivo studies have evidenced a dual role for TGF-beta: it can either function as a pro- or anti-inflammatory cytokine on inflammatory cells, participating into the initiation and resultion of inflammatory and immune responses in the airways. TGF-beta is also involved in the remodelling of the airway wall, and has in particular been related to the subepithelial fibrosis. TGF-beta is produced in the airways by inflammatory cells infiltrated in the bronchial mucosa, as well as by structural cells of the airway wall including fibroblasts, epithelial, endothelial and smooth muscle cells. By releasing TGF-beta, these different cell types may then participate into the increased levels of TGF-beta observed in bronchoalveolar lavage fluid from asthmatic patients. Taken together, these results suggest that TGF-beta may play a role in inflammation in asthma. However, as its role is dual in the modulation of inflammation, further studies are needed to elucidate the precise role of TGF-beta in the airways.     

转化生长因子-β与高氧肺损伤

高氧肺损伤以早期肺泡炎和后期肺纤维化为特征。转化生长因子-β是一种多功能的细胞因子,控制着细胞功能的多个方面,包括细胞的增殖、分化,组织修复和细胞外基质蓄积的调控,免疫和炎症反应的调节。     

Transforming growth factor-beta 1 in diabetic nephropathy

In diabetic nephropathy the extent of matrix accumulation in both glomeruli and the interstitium correlates strongly with the degree of renal insufficiency and proteinuria. Factors responsible for the deposition and accumulation of extra cellular matrix material within the kidney are therefore of considerable interest. Such factors include the potent fibrotic cytokine TGF-beta. We measured serum TGF-beta1 in patients with various stages of diabetic nephropathy, and correlated its level with different biochemical parameters. The study was conducted on: Group I: 30 patients with diabetic nephropathy (Subgroup IA: 20 patients with microalbuminuria; Subgroup IB: 10 patients with overt nephropathy), Group II: 19 diabetic patients without nephropathy (positive control), Group III: 20 healthy volunteers (negative control). Serum creatinine, Fasting and postprandial blood glucose, Fasting serum cholesterol, Glycated haemoglobin (HbA1c), Microalbumin estimation in urine, Serum TGF-beta1 estimation were done for all the studied groups. Our results showed a statistically significantly higher serum TGF-beta1 level in patients with diabetic nephropathy versus diabetic patients without nephropathy (mean +/- SD, 47.66 +/- 21.92 and 27.07 +/- 15.46 respectively) (P<0.001). Also in patients with diabetic nephropathy versus healthy controls (mean +/- SD, 47.66 +/- 21.29 and 27.05 +/- 8.95 respectively) (P<0.001). While serum TGF-beta1 concentrations were almost similar in diabetic patients without nephropathy and in healthy controls. Serum TGF-beta1 was statistically significantly higher in patients with overt nephropathy versus patients with microalbuminuria (mean+/-SD, 73.5 +/- 2.41 and 34.9 +/- 12.41) (P<0.001). Serum TGF-beta1 was significantly positively correlated with albumin excretion rate, fasting and postprandial blood glucose levels, serum cholesterol and HbA1c, these correlations were only found in diabetic patients with nephropathy but not in those without nephropathy or the control group. (r=0.86, P<0.001, r=0.444, P<0.05, r=0.375, P<0.05, r=0.532, P <0.01, r=0.696, P<0.001 respectively. HbA1c was found to be predictor of 68% of changes of serum TGF-beta1 (P<0.001) and serum cholesterol was predictor of 73% of changes of serum TGF-beta1 concentration (P<0.01). In conclusion, our results suggest that TGF-beta1 may play a key role in the development and progression of diabetic nephropathy. Accordingly, it may be also directly implicated in the functional deterioration of the kidney functions seen in patients with diabetic nephropathy, therefore beside proper glycemic control, strategies aiming at antagonizing TGF- beta1 for example by the use of specific antibodies or a specific inhibitor of TGF-beta1 may help to prevent the development or attenuate the progression of nephropathy in diabetic patients.     

Transforming growth factor-beta and hepatocyte transdifferentiation in liver fibrogenesis

Currently, hepatic stellate cells (HSC) are thought to be the major fibrotic precursor cells that transdifferentiate to fibrogenic, extracellular matrix producing myofibroblasts in inflammatory liver tissue upon transforming growth factor-beta (TGF-beta) signaling, whereas hepatocytes are thought to respond with apoptosis to this cytokine. Starting out from in vitro experiments with primary hepatocyte cultures and immortalized AML-12 cells, TGF-beta signaling in this cell type was assessed and apoptosis was found to be only a minor effect. Instead, hepatocytes undergo epithelial mesenchymal transition (EMT), a physiological process in embryogenesis and of relevance for cancerous cell transformation. In injured liver, however, this process contributes to the promotion of fibrosis. Already after a few days of culture, hepatocytes lose their epithelial honeycomb-like shape towards a fibroblast-like phenotype. We could demonstrate by microarray analysis that stimulation of hepatocytes with TGF-beta regulates the expression of genes involved in EMT and fibrosis. Among these were, for example, Snail, a known mediator of EMT, and connective tissue growth factor (CTGF), a strong inducer of fibrosis. In a mouse model, hepatocyte-specific overexpression of Smad7 was able to blunt a fibrogenic response after CCl(4) intoxication. These results emphasize the dynamic nature of liver fibrosis, challenge the paradigm of HSC as a crucial source of liver myofibroblasts and hint towards a prominent role for hepatocytes in liver fibrogenesis.     

Transforming growth factor-beta1 to the bone

TGF-beta1 is a ubiquitous growth factor that is implicated in the control of proliferation, migration, differentiation, and survival of many different cell types. It influences such diverse processes as embryogenesis, angiogenesis, inflammation, and wound healing. In skeletal tissue, TGF-beta1 plays a major role in development and maintenance, affecting both cartilage and bone metabolism, the latter being the subject of this review. Because it affects both cells of the osteoblast and osteoclast lineage, TGF-beta1 is one of the most important factors in the bone environment, helping to retain the balance between the dynamic processes of bone resorption and bone formation. Many seemingly contradictory reports have been published on the exact functioning of TGF-beta1 in the bone milieu. This review provides an overall picture of the bone-specific actions of TGF-beta1 and reconciles experimental discrepancies that have been reported for this multifunctional cytokine.     

转化生长因子β：参与结核病致病的免疫分子

转化生长因子 β(ＴＧＦ β)不仅在结核病发展过程中产生过量而且在结核分支杆菌感染的活动性病灶部位表达。ＴＧＦ β能够抑制Ｔ细胞的激活及其功能 ,其中包括一些重要的细胞因子如白细胞介素 2 (ＩＬ 2 )、γ干扰素 (ＩＦＮ γ)等的产生。ＴＧＦ β和其他细胞因子如肿瘤坏死因子α(ＴＮＦ α)具有协同作用 ,可以形成具有结核病特征的组织破坏。ＴＧＦ β过量产生引起结核病的免疫病理改变提示 ,ＴＧＦ β的抑制剂可以作为活动性结核病感染过程抗结核化疗的辅助治疗。一、ＴＧＦ β的免疫功能1.ＴＧＦ β抑制Ｔ细胞的免疫应答 :ＴＧＦ β抑…     

Transforming growth factor—β1in invasion and metastasis in colorectal cancer

AIM：To investigate the role of TGFβ1 in invasion and metastasis in colorectal cancer by analysing TGFβ1 correlated wity depth of tumor invasion,stage and metastasis.METHODS:Serum TGFβ1levels were determined in50patients with colorectal cancer and 30healthy volunteers using a TGFβ1 enzyme-linked immunosorbent assay.TGFβ1 expression in primary and lymph node metastatic lesions were detected in 98cases of colorectal cancer by immunohistochemical staining and in situ hybridization.RESULTS:Serum levels of TGFβ1 in patients with colorectal cancer(40&#177;18μg&#183;L^-1)were significantly higher than those in the healthy control group(19&#177;8μg&#183;L^-1),P&lt;0.05.Elevated levels of serum TGFβ1were found in 60%of patients with colorectal cancer when the mean+2s was used as the upper limit of the normal range(35.1μg&#183;L^-1).Increases in serum TGFβ1 levels were significantly asociated with Dukei‘s stage(P&lt;0.05),but there was no significant difference between,Duki‘s stage Bpatients and Dukei‘s stage Cpatients.In the cytoplasm of cancer cells,TGFβ1 was immunostained in37.8%(37/98)of colorectal cancer,and this expression was confirmed by in situ hybridization,Among35cases of colorectal cancer with lymph node metastatic lesions,TGFβ1 positive staining was found in18(51.4%)cases of primary tumor,and 25(71.4%)cases with lymph node metastatic lesions,respectively,Of17cases with no staining in the primary lesion.7(41.2%)casesshowed TGFβ1 staining in the metastatic lesion.Serum TGFβ1 levels and TGFβ1 expression in colorectal cancer tissues were correlated significantly with depth of tumor invasion,stage and metastasis,Patients in stage C-D,T3-T4and with metastasis had significantly higher TGFβ1 levels than patients in stage A-B,T1-T2and without metastasis(P&lt;0.05).CONCLUSION:These results suggest that transforming growth factor-β1 is closely related to the invasion and metastasis of colorectal cancer.It increased the invasive and metastatic potential of tumor by altering a tumor microenvironment.TGFβ1 may be used as a possible biomarke.     

Transforming growth factor-beta gene polymorphism in sarcoidosis and tuberculosis patients.

SETTING: Transforming growth factor-beta (TGF-beta) plays an important role in many diseases, influencing as it does such processes as immune responses, fibrosing processes, and angiogenesis. Recently, polymorphisms have been described for TGF-beta that are associated with the risk of several diseases. In this study, we investigated whether TGF-beta 1 polymorphism has an effect on sarcoidosis and tuberculosis. OBJECTIVE: TGF-beta 1 Codon 10 T869C polymorphism was investigated in 110 healthy control subjects, 104 sarcoidosis patients, and 101 tuberculosis patients. DESIGN: The TGF-beta genotype was determined using polymerase chain reaction restriction fragment length polymorphism. RESULTS: We found no significant differences in TGF-beta genotypes between sarcoidosis patients and healthy controls or tuberculosis patients and controls. The long axis of the tuberculin skin test was larger in the CC type compared with the CT type. However, there was no association between the TGF-beta genotype and the roentgenographic stage, the disappearance of shadows, or organ involvement in sarcoidosis, nor any association between genotype, the extent or type of roentgenographic shadow, or detected volume of tubercle bacilli in tuberculosis. CONCLUSION: From the results, we believe that TGF-beta polymorphisms on the whole do not have a strong influence on disease onset or clinical progression in sarcoidosis and tuberculosis, although this polymorphism might have an effect on the immune response in a tuberculosis host.     

Transforming growth factor-beta differentially regulates oval cell and hepatocyte proliferation

Oval cells are hepatocytic precursors that proliferate in late-stage cirrhosis and that give rise to a subset of human hepatocellular carcinomas. Although liver regeneration typically occurs through replication of existing hepatocytes, oval cells proliferate only when hepatocyte proliferation is inhibited. Transforming growth factor-beta (TGF-beta) is a key inhibitory cytokine for hepatocytes, both in vitro and in vivo. Because TGF-beta levels are elevated in chronic liver injury when oval cells arise, we hypothesized that oval cells may be less responsive to the growth inhibitory effects of this cytokine. To examine TGF-beta signaling in vivo in oval cells, we analyzed livers of rats fed a choline-deficient, ethionine-supplemented (CDE) diet for phospho-Smad2. Phospho-Smad2 was detected in more than 80% of hepatocytes, but staining was substantially reduced in oval cells. Ki67 staining, in contrast, was significantly more common in oval cells than hepatocytes. To understand the inverse relationship between TGF-beta signaling and proliferation in oval cells and hepatocytes, we examined TGF-beta signaling in vitro. TGF-beta caused marked growth inhibition in primary hepatocytes and the AML12 hepatocyte cell line. Two oval cell lines, LE/2 and LE/6, were less responsive. The greater sensitivity of the hepatocytes to TGF-beta-induced growth inhibition may result from the absence of Smad6 in these cells. CONCLUSION: Our results indicate that oval cells, both in vivo and in vitro, are less sensitive to TGF-beta-induced growth inhibition than hepatocytes. These findings further suggest an underlying mechanism for the proliferation of oval cells in an environment inhibitory to hepatocytic proliferation.