Epidermal growth factor (EGF) antagonizes transforming growth factor (TGF)-beta1-induced collagen lattice contraction by human skin fibroblasts

Wound contraction plays an important role in healing, but in extreme conditions, it may lead to excessive scar formation and pathological wound contracture. To date, the key regulator of excessive contracture is known to be transforming growth factor-beta (TGF-beta1). In this study, we have evaluated epidermal growth factor (EGF) antagonism in fibroblast-populated collagen lattice (FPCL) gel contraction, which has been generally used as an in vitro model thought to mimic wound contraction in vivo. As expected, TGF-beta1 treatment enhanced normal fibroblast-induced collagen gel contraction in a dose-dependent manner. In contrast, EGF did not affect normal gel formation, but significantly antagonized TGF-beta1-induced gel formation (p<0.05 at 100 ng/ml), whereas the other growth factor, platelet-derived growth factor (PDGF), did not altered either normal or TGF-beta1-induced gel contractions. Similarly, EGF treatment, but not PDGF, also significantly suppressed TGF-beta1 release that was autologously elicited by TGF-beta1 treatment (p<0.01 at 100 ng/ml). Therefore, the results suggest that EGF may negatively regulate the role of TGF-beta1 through attenuating autologous release of TGF-beta1.

Sp1 decoy transfected to carcinoma cells suppresses the expression of vascular endothelial growth factor, transforming growth factor beta1, and tissue factor and also cell growth and invasion activities

Vasculature development is thought to be an important aspect in the growth and metastasis of solid tumors. Among the angiogenic factors produced by tumor cells, vascular endothelial growth factor is considered to be the most potent and pathologically important. The synthesis of this growth factor has been shown to be modulated through Sp1 function following stimulation by tumor necrosis factor alpha (TNF-alpha). Oligodeoxynucleotides (ODNs) were synthesized with either the consensus sequence for Sp1 binding (Sp1 decoy ODNs) or a mutated form of this sequence (mt-Sp1 decoy ODNs). Using the hemagglutinating virus of Japan (HVJ)-liposome method, we transferred these ODNs into cultured cancer cells (A549 and U251 cells). The TNF-alpha-mediated expression of both VEGF and transforming growth factor beta1 and tissue factor (TF) by the cancer cells could be simultaneously suppressed to less than 30% by transfection of Sp1 decoy ODNs but not by mt-Sp1 decoy ODNs. In addition, in vitro invasiveness, synthesis of mRNA for urokinase-type plasminogen activator, and cell proliferation of both cell lines were also inhibited to 40% by the transfection of only Sp1 decoy ODNs. These results suggested that the Sp1 decoy strategy would be effective for regulating tumor growth by simultaneously reducing cancer cell (a) angiogenic growth factor expression, (b) proliferation, and (c) invasiveness.

alpha-Melanocyte stimulating hormone acts as a selective inducer of secretory functions in human mast cells

In the present study, we have investigated the pro-opiomelanocortin (POMC)-derived neuropeptide alpha-MSH for its ability to modulate activation of human mast cells. The in vitro ability of purified human skin mast cells to secrete various types of mast cell mediators was monitored in response to alpha-MSH at the mRNA and at the protein level. Picomolar concentrations of alpha-MSH induced a dose-dependent release of histamine from isolated human skin mast cells and from skin punch biopsies. However, no effect of alpha-MSH was seen regarding the expression of IL-1, IL-6, IL-8, TGF-beta, and TNF-alpha. Melanocortin receptor MC-1 was identified at the transcriptional level by RT-PCR analysis but not at the protein level, whereas, in leukemic human mast cells (HMC-1), the mRNAs and the proteins for the MC-1 and MC-5 receptor were identified. These results suggest that alpha-MSH may selectively induce acute inflammatory effects via secretion of histamine.

A nodal signaling pathway regulates the laterality of neuroanatomical asymmetries in the zebrafish forebrain

Animals show behavioral asymmetries that are mediated by differences between the left and right sides of the brain. We report that the laterality of asymmetric development of the diencephalic habenular nuclei and the photoreceptive pineal complex is regulated by the Nodal signaling pathway and by midline tissue. Analysis of zebrafish embryos with compromised Nodal signaling reveals an early role for this pathway in the repression of asymmetrically expressed genes in the diencephalon. Later signaling mediated by the EGF-CFC protein One-eyed pinhead and the forkhead transcription factor Schmalspur is required to overcome this repression. When expression of Nodal pathway genes is either absent or symmetrical, neuroanatomical asymmetries are still established but are randomized. This indicates that Nodal signaling is not required for asymmetric development per se but is essential to determine the laterality of the asymmetry.

Gene expression of transforming growth factor-beta 3 and tissue inhibitor of metalloproteinase type 1 during membranous bone healing in rats

A number of growth factors have been implicated in fracture repair. Transforming growth factor-beta 3 (TGF-beta 3) is believed to be involved in osteoblast proliferation, chemotaxis, and collagen synthesis. The collagens act as the scaffolding for new bone matrix formation, whereas tissue inhibitors of metalloproteinases (TIMPs) may help regulate matrix remodeling in bone repair. Despite their hypothesized integral role in fracture repair, the temporal expression of these molecules in membranous bone fracture healing remains unknown. The objective of this study was to assess the temporal pattern of TGF-beta 3 and TIMP type 1 (TIMP-1) expression in rat mandibular fracture healing. Twenty-eight adult male Sprague-Dawley rats underwent a mandibular osteotomy, and the healing regenerate was harvested on postoperative days 3, 5, 7, 9, 23, and 37. Total cellular ribonucleic acid was isolated, and Northern analysis was performed. TGF-beta 3 expression was downregulated dramatically 3 days after the osteotomy and remained less than 20% of control levels throughout repair. In marked contrast, TIMP-1 gene expression, low during early repair, increased more than twofold over control at later time points. Understanding the temporal pattern of gene expression during membranous fracture healing has important clinical implications because elucidating these mechanisms may lead to appropriate biomolecular approaches to augment membranous bone fracture healing.

Participation of pigment epithelium of iris and ciliary body in ocular immune privilege. 2. Generation of TGF-beta-producing regulatory T cells

PURPOSE

To determine whether T cells exposed to cultured iris and ciliary body pigment epithelial (I/CB PE) cells acquire the capacity to modify the activation, differentiation, and effector functions of bystander T cells, and if so, to identify the mechanism.

METHODS

T cells from naive BALB/c mice were cultured with I/CB PE cells, x-irradiated, and used as regulators (a) of T-cell activation in vitro and (b) of delayed hypersensitivity expression in vivo. Neutralizing anti-TGF-beta and -IL-10 antibodies were used to abolish regulatory function. T-cell activation was assessed for proliferation by [(3)H]thymidine incorporation and for IL-2, IFN-gamma, IL-4, and IL-10 production by semi-quantitative RT-PCR for mRNA and by supernatant analysis by ELISA. I/CB PE-exposed T cells were evaluated for mRNA content of IFN-gamma, IL-4, TNF-alpha, TGF-beta1, TGF-beta2, and IL-10, and their supernatants were analyzed for content of TGF-beta.

RESULTS

T cells exposed to I/CB PE cells inhibited anti-CD3-driven activation of bystander naive T cells in vitro and suppressed the expression of delayed hypersensitivity in vivo. Bystander T cells cocultured with I/CB PE-exposed T cells failed to proliferate and secreted high levels of IL-4 and IL-10 but low amounts of IL-2 and IFN-gamma. Regulation of bystander T-cell activation was mediated via enhanced secretion of TGF-beta by I/CB PE-exposed T cells.

CONCLUSIONS

T cells exposed to cultured I/CB PE cells were induced to secrete active and latent TGF-beta, which conferred on the T cells the capacity to inhibit the differentiation as well as the effector function of Th1-type cells.

Chlamydia pneumoniae induces interleukin-10 production that down-regulates major histocompatibility complex class I expression

Recently, it was demonstrated that CD8(+) T cells are important for the response against Chlamydia pneumoniae. By use of the human monocytic cell line U937 and human monocytes taken from peripheral blood, we investigated the effect of infection on various molecules critical for CD8(+) T cell function. A strong secretion of interleukin (IL)-10 by infected cells was observed, together with an inhibited expression of major histocompatibility complex (MHC) class I antigens, but without significant alteration of tumor growth factor-beta secretion or MHC class II expression. Recombinant IL-10 added to uninfected U937 cells decreased the expression of MHC class I, whereas blocking antibodies to IL-10 and its receptor abolished the C. pneumoniae-induced inhibition of MHC class I expression. Analysis of our data provides evidence that IL-10 secretion induced by C. pneumoniae infection of monocytic cells down-regulates the expression of MHC class I molecules and thereby might reduce the presentation of bacterial epitopes by MHC. This would decrease the ability of CD8(+) T cells to eliminate infected cells.

[Expression of TGF-beta 1 and proliferation of collagen in myocardium in viral myocarditis]

To investigate the tissue repair of acute viral myocarditis, and to explore the diagnostic method of slight viral myocarditis in forensic pathology. Slight viral myocarditis model was induced in Balb/c murine by CVB3. Collagen proliferation in myocardium of mice with myocarditis was observed by special staining. The hearts of mice and human(9 cases) with myocarditis were studied LSAB-immunohistochemically with anti-TGF-beta 1 antibody. In the study, the proliferation of collagen was seen in myocardium in acute viral myocarditis. Generous expression of TGF-beta 1 was found in the myocardium of mice and human with myocarditis. The quantity of collagen proliferation and expression of TGF-beta 1 was positive correlation. It is concluded that the tissue repair exists in acute viral myocarditis and that positive staining of myocardium for TGF-beta 1 is a sensitive index of myocardial damage and tissue repair.

Interaction of nitric oxide and transforming growth factor-beta1 induced by angiotensin II and mechanical stretch in rat renal tubular epithelial cells

PURPOSE

Changes in intrarenal pressure accompanying unilateral ureteral obstruction can result in tubular mechanical stretch and mediator release from renal tubules. Therefore, we examined the synthesis of nitric oxide and transforming growth factor-beta (TGF-beta), and their interaction in rat renal epithelial cells (NRK-52E) exposed to either angiotensin II or mechanical stretch.

MATERIALS AND METHODS

NRK-52E were exposed to either angiotensin II or mechanical stretch. Nitrite and TGF-beta in the supernatant were assessed by the Greiss reaction and bioassay, respectively. The level of cell hypertrophy and intracellular TGF-beta protein was determined by flow cytometry. TGF-beta messenger RNA and inducible nitric oxide synthase protein were detected by reverse transcriptase polymerase chain reaction and Western blot, respectively.

RESULTS

Angiotensin II stimulated TGF-beta1 and nitric oxide. The nitric oxide synthase inhibitor, N-nitro-L-arginine (L-NAME) or angiotensin II type I receptor blocker, losartan, inhibited nitric oxide and TGF-beta1 induced by angiotensin II. Flow cytometry showed that either L-NAME or losartan inhibited angiotensin II induced cell hypertrophy. TGF-beta1 inhibited iNOS protein and nitric oxide, whereas an anti-TGF-beta antibody enhanced iNOS. Mechanical stretch induced TGF-beta, inducible NOS protein and nitric oxide. However, TGF-beta expression was not affected by L-arginine or L-NAME when cells were exposed to mechanical stretch.

CONCLUSIONS

These results demonstrate that nitric oxide is an intermediate in angiotensin II stimulated TGF-beta1 expression but not in stretch induced TGF-beta expression, and that TGF-beta1 is a negative regulator of nitric oxide in rat renal epithelial cells. The complex interaction of these cytokines may be a target for intervention in the fibrotic and apoptotic processes in the obstructed kidney.

Effect of glucose on intercellular junctions of cultured human peritoneal mesothelial cells

During continuous ambulatory peritoneal dialysis, the peritoneum is directly and continuously exposed to unphysiologic peritoneal dialysis fluid; the resulting mesothelial damage has been suggested to cause loss of ultrafiltration and dialysis efficacy. The present study investigated the effect of a high glucose concentration on cultured human peritoneal mesothelial cells to clarify the cause of decreased dialysis efficacy during prolonged peritoneal dialysis. High glucose caused a concentration-dependent decrease in cell proliferation, damage to the intercellular junctions, and excess production of transforming growth factor-beta (TGF-beta). The levels of intercellular junctional proteins (ZO-1, E-cadherin, and beta-catenin) were decreased, and immuno-staining by anti-ZO-1 and anti- beta-catenin antibodies became weaker and often discontinuous along the cell contour. Mannitol had similar but weaker effects at the same osmolality, and an anti-TGF-beta neutralizing antibody reduced the effects of high glucose. Therefore, these effects were induced not only by glucose itself but also by hyperosmolality and by a glucose-induced increase of TGF-beta. These findings suggest that the peritoneal mesothelium is damaged by prolonged peritoneal dialysis using high glucose dialysate and that impairment of the intercellular junctions of peritoneal mesothelial cells by high glucose dialysate induces peritoneal hyperpermeability and a progressive reduction in dialysis efficacy.

Dendritic cells prime in vivo alloreactive CD4 T lymphocytes toward type 2 cytokine- and TGF-beta-producing cells in the absence of CD8 T cell activation

The mechanisms that influence the polarization of CD4 T cells specific for allogeneic MHC class II molecules in vivo are still poorly understood. We have examined the pathway of alloreactive CD4 T cell differentiation in a situation in which only CD4 T cells could be activated in vivo. In this report we show that priming of adult mice with allogeneic APC, in the absence of MHC class I-T cell interactions, induces a strong expansion of type 2 cytokine-producing allohelper T cells. These alloantigen-specific CD4 T cells directly recognize native allogeneic MHC class II molecules on APC and secrete, in addition to the prototypic Th2 cytokines IL-4, IL-5, and IL-10, large amounts of TGF-beta. The default Th2-phenotype acquisition is not genetically controlled and occurred both in BALB/c and C57BL/6 mice. CD8 T cells are the principal cell type that controls CD4 T cell differentiation in vivo. Furthermore, we demonstrate that strong Th2 priming can be induced not only with allogeneic splenocytes but also with a low number of bone marrow-derived dendritic cells. Finally, using a passive transfer system, we provide direct evidence that CD8 T cell expansion in situ promotes alloreactive Th1 cell development principally by preventing their default development to the Th2 pathway in a mechanism that is largely IFN-gamma independent. Therefore, this work demonstrates that type 2 cytokine production represents a dominant pathway of alloreactive CD4 T cell differentiation in adult mice, a phenomenon that was initially thought to occur only during the neonatal period.

Renal cytokine responses in acute Escherichia coli pyelonephritis in IL-6-deficient mice

The aim of this study was to investigate the influence of IL-6 on mortality, bacterial growth and cytokine expression in experimental acute pyelonephritis. Female IL-6-deficient mice and their wild-type counterparts, 8-10 weeks old, were infected with Escherichia coli CFT 073 or injected with NaCl 0.9% (w/v) via the urethra and thereafter obstructed for 6 h. Animals were killed at 48 h, 6 days or 8 weeks and cytokine and bacterial renal levels were assessed at each time point. We found that IL-6-deficient mice had increased mortality and extensive renal bacterial growth on day 6, compared with wild-type mice (P < 0.05) and the histopathological changes were generally more severe and widespread in the IL-6-deficient mice. Peak mRNA expression of IL-1beta, IL-4, IL-10, IL-12 and interferon-gamma (IFN-gamma) occurred 48 h after infection in both IL-6 knock out and wild-type mice. Transforming growth factor-beta (TGF-beta) levels also peaked at 48 h in E. coli-infected wild-type mice, while in the IL-6-deficient strain both TGF-beta mRNA and protein levels were significantly lower at 48 h than wild-type levels (P < 0.0008 and P < 0.03, respectively) and remained stationary throughout the study period. Animals injected with NaCl 0.9% (w/v) displayed a similar decrease in TGF-beta expression (P < 0.02). When splenocytes from the IL-6-deficient mice were incubated with murine recombinant IL-6, TGF-beta levels increased to those of wild-type mice. No increase was observed when splenocytes from wild-type mice were incubated with the same doses of rIL-6. We therefore conclude that IL-6 plays an important role in bacterial clearance and directly influences the TGF-beta levels in experimental acute pyelonephritis. We also demonstrate that urethral obstruction per se induces an increase in TGF-beta the magnitude of which is decreased in IL-6-deficient mice.

alpha(1)-Adrenergic stimulation perturbs the left-right asymmetric expression pattern of nodal during rat embryogenesis

BACKGROUND

Normal development of the left/right (L/R) body axis leads to the characteristic sidedness of asymmetric body structures, e.g., the left-sided heart. Several genes are now known to be expressed with L/R asymmetry during embryogenesis, including nodal, a member of the transforming growth factor-beta (TGF-beta) family. Mutations or experimental treatments that affect L/R development, such as those that cause situs inversus (reversal of the sidedness of asymmetric body structures), have been shown to alter or abolish nodal's asymmetric expression.

METHODS

In the present study, we examined the effects on nodal expression of alpha(1)-adrenergic stimulation, known to cause a 50% incidence of situs inversus in rat embryos grown in culture, using reverse transcription-polymerase chain reaction assay and whole-mount in situ hybridization assay.

RESULTS

In embryos cultured with phenylephrine, an alpha(1)-adrenergic agonist, nodal's normal asymmetric expression only in the left lateral plate mesoderm was altered. In some treated embryos, nodal expression was detected in either the left or right lateral plate mesoderm. However, most treated embryos lacked lateral plate mesoderm expression. In addition, the embryos that did show expression were at a later stage than when nodal expression is normally found.

CONCLUSIONS

Our results demonstrate that alpha(1)-adrenergic stimulation delays the onset and perturbs the normal asymmetric pattern of nodal expression. Either of these effects might contribute to situs inversus.

F(2)-isoprostanes mediate high glucose-induced TGF-beta synthesis and glomerular proteinuria in experimental type I diabetes

BACKGROUND

The recently discovered arachidonic acid derivatives, isoprostanes, are increased in pathological conditions associated with oxidative stress, such as diabetes. No role has yet been described for isoprostanes during the development of diabetic nephropathy. Cell culture in high ambient glucose has been used as a model in elucidating cellular mechanisms underlying diabetic nephropathy. Among the growth factors involved in the effect of high glucose, transforming growth factor-beta (TGF-beta) has been described as playing a key role in the development of nephropathy.

METHODS

Streptozotocin-induced diabetic rats were supplemented in their diet with the antioxidant vitamin E (1000 U/kg diet). Blood and urine samples were taken to determine renal function and isoprostane concentration, as determined by gas chromatography/mass spectrometry. Glomerular mesangial and endothelial cells were cultured in high ambient glucose to determine the synthesis of isoprostanes and the role of isoprostanes in high glucose-induced synthesis of TGF-beta.

RESULTS

Streptozotocin-induced diabetic rats had marked increases in plasma levels and urinary excretion rates of F(2)-isoprostanes. Dietary supplementation with vitamin E normalized (plasma) and reduced (urine) isoprostane levels and, surprisingly, improved proteinuria and blood urea nitrogen (BUN) levels. High ambient glucose increased F(2)-isoprostane synthesis in glomerular endothelial and mesangial cells in culture. Incubation of glomerular cells with F(2)-isoprostanes stimulated the production of TGF-beta.

CONCLUSIONS

Increased F(2)-isoprostane synthesis during diabetes appears to be responsible in part for the increase in renal TGF-beta, a well-known mediator of diabetic nephropathy.

[Correlation study of TGF beta expression in diethylnitrosamine-induced rat liver cancer and mast cells in its vicinity]

OBJECTIVE

To study the correlation between tumor cell expression of TGF beta and the amount of surrounding mast cells in hepatocarcinogenesis.

METHODS

Hepatocarcinoma was induced by diethylnitrosamine (DENA) in rats. The expression of TGF beta was examined immunohistochemically, and mast cells were identified by Alcian blue staining. The results were undergone cell imaging analysis.

RESULTS

Positive expression of TGF beta was observed in the cytoplasm of the hepatocarcinoma cells. The intensity of expression differd in various groups of experiment. There was a positive correlation between the intensity of the TGF beta expression in hepatocarcinoma cells and the amount of mast cells surrounding the tumor nodules (P < 0.01).

CONCLUSION

Mast cell infiltration in DENA-induced rat hepatoma may be due to the chemotactic effect of TGF beta expressed in tumor cells.

[The potential role of growth factor in the airway wall remodeling of a chronic obstructive pulmonary disease rat model and the effects of drugs on them]

OBJECTIVE

To evaluate the expression and distribution of transforming growth factor-beta1 (TGF-beta1), epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) in the lung tissue of chronic obstructive pulmonary (COPD) rat models and the relationship between these growth factors and the airway wall remodeling. The effects of drugs on them were also investigated.

METHODS

The COPD rat model (model group) was established by intratracheal instillation of lipopolysaccharide twice and daily exposure to cigarette smoking. Drug intervention groups received daily inhalation of heparin since the second week and TGF-beta1 monoclonal antibody (TB21) 0.5 mg twice through the tail veins. At the end of four weeks, the thickness of the smooth muscle and collagen in bronchi and pulmonary arterioles were measured by computer image analyzer, also the protein and gene relative content of these growth factors as well as the effects of drugs on them were observed.

RESULTS

There was a significant increase in the smooth muscle and collagen thickness in the bronchi and pulmonary arterioles of the model group in comparison with that of the control group (P < 0.01), the relative contents for TGF-beta1, EGF and bFGF in the epithelial cells of the bronchi, endothelial cells of the pulmonary arterioles and alveolar macrophages of the model group were significantly higher than those of control group (P < 0.001 approximately 0.05). The relative content for TGF-beta1 in TB21 group was significantly lower than that of model group (P < 0.01). These were statistical positive relationships between the smooth muscle e thickness of bronchi and the relative contents for TGF-beta1, EGF and bFGF in the epithelial cells, between the collagen thickness of the bronchi and the relative content for TGF-beta1, between the smooth muscle thickness of the pulmonary arterioles and the relative content for TGF-beta1 and EGF in the endothelial cells (P < 0.05 approximately 0.01).

CONCLUSION

TGF-beta1, EGF and bFGF may play an important role in the airway wall and pulmonary arteriole structure remodeling in COPD, the intervention against TGF-beta1 and long term inhalation of heparin mat be helpful for the inhibition of airway wall remodeling in human COPD and worth of further observation.

Mutations in the gene encoding the latency-associated peptide of TGF-beta 1 cause Camurati-Engelmann disease

Camurati-Engelmann disease (CED; MIM 131300), or progressive diaphyseal dysplasia, is a rare, sclerosing bone dysplasia inherited in an autosomal dominant manner. Recently, the gene causing CED has been assigned to the chromosomal region 19q13 (refs 1-3). Because this region contains the gene encoding transforming growth factor-beta 1 (TGFB1), an important mediator of bone remodelling, we evaluated TGFB1 as a candidate gene for causing CED.

[Clinico-morphological and molecular-biological characteristics of idiopathic fibrous alveolitis and lung sarcoidosis]

Lung biopsies of 16 patients with classic idiopathic fibrosing alveolitis (IFA) and 6 patients with sarcoidosis were studied immunohistochemically. It was found that adenomatous hyperplasia (AH) and fibrosing in IFA are potentiated by high expression of thrombocytic growth factor (TGF) and insulin-like growth factor type 1 (IGF-1). Tumor necrosis factor alpha (TNFa) in IFA is actively produced at early stages of the disease. TNFa is drastically reduced in IFA with atypical AH. High level of TNFa produced by alveolar macrophage, pneumocytes type 2 and by other cells is observed in the lungs in sarcoidosis. The level of transforming growth factor (B1-TGF) is rather low in sarcoidosis this being combined with weak interstitial fibrosis (3.75 against 5.06 in IFA). Sarcoidosis granuloma contains proliferating epithelioid cells (as judged by Ki-67), produces a high amount of FTN (4.66), moderate amount of cell fibronectin (2.7), fibroblast growth factor, beta-TGF and IGF-system (1.7; 1.1; 0.8, respectively). Thus, IFA and sarcoidosis are distinguished not only morphologically but by the cytokine profile as well. This implies different approaches to their diagnosis and treatment.

Activation of latent transforming growth factor-beta1 is induced by mannose 6-phosphate/insulin-like growth factor-II receptor

This study was conducted to further explore the mechanism of transforming growth factor beta1 (TGF-beta1) activation, which plays a critical role in many physiological and pathological conditions. We have previously shown that the large (270 kDa), but not small (40 kDa), mannose 6-phosphate receptors facilitate the cellular response to latent TGF-beta1 released from genetically modified cells. In this study, we explored the role of cell membrane associated transglutaminase and plasmin in mannose 6-phosphate receptor induced latent TGF-beta activation using MS and MS-9 cells bearing either no receptors or the 270 kDa mannose 6-phosphate/insulin-like growth factor II receptors, respectively. As a source of latent TGF-beta1, PA317 cells were transfected with either pLin-TGF-beta1 vector or pLin retroviral vector with no TGF-beta1 insert using calcium phosphate precipitation. The latency and bioactivity of TGF-beta1 in conditioned medium derived from transfected PA317 cells were evaluated by enzyme-linked immunosorbent assay and mink lung epithelial cell growth inhibition assay, respectively. The level of latent TGF-beta1 was 13-fold higher (20.1 +/- 0.4 vs. 1.5 +/- 0.03 ng/ml) in conditioned medium from pLin-TGF-beta1 transfected cells than that of control. The latency and bioactivity of TGF-beta1 released from pLin-TGF-beta1 transfected cells were confirmed by evaluation of 3H-thymidine incorporation in Mv1Lu epithelial cells treated with non- and heat-activated 10% conditioned medium. The results showed a significantly lower 3H-thymidine incorporation in Mv1Lu epithelial cells treated with heat-activated PA317 conditioned medium (4% of control) relative to those treated with either control or nonheated conditioned medium. This inhibition was abrogated by addition of 40 microg/ml of TGF-beta1 neutralizing antibody. The level of 3H-thymidine incorporation was then evaluated in MS-9 cells receiving Dulbecco's modified Eagle medium containing either 0% 10%, 30% or 50% volumes of nonactivated PA317 conditioned medium for 24 hours. The results showed a markedly lower proliferation in response to 30% and 50% conditioned medium used in MS-9 cells. Under similar experimental conditions, addition of only mannose 6-phosphate, but not fructose 6-phosphate or mannose 1-phosphate, at 1 mM concentration restored the MS-9 cell proliferative response to latent TGF-beta1. The inhibitory effects of latent TGF-beta1 on MS-9 cell proliferation were restored by addition of either TGF-beta1 neutralizing antibody or cystamine, a transglutaminase inhibitor. In contrast, addition of aprotinin, a plasmin inhibitor, had a marginal influence on inhibitory effects of latent TGF-beta1 on MS-9 cell proliferation. Interestingly, a mixture of latent TGF-beta1 + MS-9 cell membranes, but not MS cell membranes, also inhibited the mink lung epithelial cell proliferation (34% of control). These findings indicate that mannose 6-phosphate/insulin-like growth factor II receptors are involved in latent TGF-beta activation and that is at least partly dependent on cell membrane associated transglutaminase, but not on plasmin.

mRNA expression of type I and type II receptors for activin, transforming growth factor-beta, and bone morphogenetic protein in the murine erythroleukemic cell line, F5-5.fl

OBJECTIVE

Intracellular signaling of activin and transforming growth factor-beta (TGF-beta) is thought to be mediated by the same molecules (Smad2/3 and Smad4). Although differentiation of murine erythroleukemia F5-5.fl cells is induced by activin, it is not induced by TGF-beta, suggesting that at some point TGF-beta signaling is defective. The aim of this study was to investigate the unresponsiveness of F5-5.fl cells to TGF-beta.

DESIGN

mRNA expression of ligands, receptors, and signal mediators for the TGF-beta family was examined in F5-5.fl cells using RT-PCR.

RESULTS

Activin induced erythrodifferentiation of F5-5.fl cells in a dose-dependent manner. Neither TGF-beta1 nor bone morphogenetic protein (BMP)-4 affected the differentiation of F5-5.fl cells in the presence or absence of activin. Although mRNAs of TGF-betas (TGF-beta1, TGF-beta2 and TGF-beta3) were detected, those of inhibin/activin (alpha-, betaA- and betaB-subunits) and BMPs (BMP-2, BMP-4 and BMP-7) could not be detected in the cells, suggesting that neither activins nor BMPs are produced in F5-5.fl cells. The expression of both type I (ALK-4/ActRIB) and type II (ActRII) receptors for activin was detected in F5-5.fl cells. In contrast, while the expression of type I receptor for TGF-beta (ALK-5/TbetaRI) was detected, that of type II receptor (TbetaRII) was not. The mRNA of all Smads examined was detected in F5-5.fl cells.

CONCLUSIONS

A defect in the type II receptor might cause unresponsiveness to TGF-beta in F5-5.fl cells. An erythrodifferentiation assay using F5-5.fl cells would be useful for measuring net activin activity because it would not be necessary to consider endogenous activins and BMPs.

Role of monocyte chemoattractant protein-1 in cardiovascular remodeling induced by chronic blockade of nitric oxide synthesis

BACKGROUND

Chronic inhibition of endothelial nitric oxide (NO) synthesis by the administration of N:(omega)-nitro-L-arginine methyl ester (L-NAME) to rats induces early vascular inflammatory changes (monocyte infiltration into coronary vessels and monocyte chemoattractant protein-1 [MCP-1] expression) as well as subsequent arteriosclerosis (medial thickening and perivascular fibrosis) and cardiac fibrosis. However, the role of MCP-1 in this process is not known.

METHODS AND RESULTS

We investigated the effect of a specific monoclonal anti-MCP-1 neutralizing antibody in rats treated with L-NAME to determine the role of monocytes in the regulation of cardiovascular remodeling. We found increased expression of MCP-1 mRNA in vascular endothelial cells and monocytes in inflammatory lesions. Cotreatment with an anti-MCP-1 antibody, but not with control IgG, prevented the L-NAME-induced early inflammation and reduced late coronary vascular medial thickening. In contrast, the anti-MCP-1 antibody did not decrease the development of perivascular fibrosis, the expression of transforming growth factor (TGF)-beta(1) mRNA, or systolic pressure overload induced by L-NAME administration.

CONCLUSIONS

These results suggest that MCP-1 is necessary for the development of medial thickening as well as monocyte recruitment. In contrast, the pathogenesis of fibrosis may involve other factors, such as TGF-beta(1).

Kinetics of expression of connective tissue growth factor gene during liver regeneration after partial hepatectomy and D-galactosamine-induced liver injury in rats

Connective tissue growth factor (CTGF) is up-regulated by TGF-beta1 during wound healing. The present study examined the expression of CTGF during regeneration after 70% partial hepatectomy (PH) or d-galactosamine (GalN)-injured liver in rats. CTGF, TGF-beta1, and type I collagen mRNAs were semiquantified by a ribonuclease protection assay. After PH, TGF-beta1 and type I collagen were increased at 2-6 h and at 12-48 h. CTGF increased at 6 h and returned to the control level thereafter. The ribonuclease protection assay of cultured hepatic stellate cells (HSC) and in situ hybridization suggest that the cells express CTGF along sinusoid might be HSCs. After GalN administration, CTGF increased at 2-96 h with a shoulder peak at 6-12 h followed by a main peak at 24 h. TGF-beta1 and type I collagen were up-regulated with kinetics similar to those of CTGF. The different kinetics between PH and GalN regenerations indicate that regulation of CTGF in the two processes is different. Higher TGF-beta1 expression after inflammatory/necrotic process in the GalN regeneration may caused the prolonged CTGF expression.

Endothelin stimulates transforming growth factor-beta1 and collagen synthesis in stellate cells from control but not cirrhotic rat liver

Interactions between hepatic stellate cells and endothelin-1 are implicated in liver fibrosis. We determined endothelin-1, its receptors and its effects on the synthesis of a fibrogenic agent transforming growth factor (TGF)-beta1 and collagen in stellate cells from control and CCl(4)-induced cirrhotic rats. The basal synthesis of endothelin-1, TGF-beta1 and collagen was much higher in cirrhotic stellate cells than in control cells. Endothelin-1 stimulated TGF-beta1 and collagen synthesis via endothelin ET(A) and endothelin ET(B) receptors, respectively, in control stellate cells, but did not elicit these effects in the cirrhotic cells despite increased density of the respective receptor subtypes in them. These results indicate that the actions of endothelin-1 on stellate cells may be an important physiological mechanism in maintenance of hepatic architecture. However, inability of endothelin-1 to stimulate TGF-beta1 and collagen synthesis in cirrhotic stellate cells suggests that it does not influence fibrogenic activity by direct action on them probably because the processes are already maximally activated.

Rapamycin induces transforming growth factor-beta production by lymphocytes

BACKGROUND

Under certain conditions rapamycin and transforming growth factor- (TGF) beta have similar immunoregulatory effects, suggesting a potential functional link between rapamycin and TGF-beta.

METHODS

Splenic leukocytes were stimulated in vitro with anti-CD3 or with allogeneic cells in vivo in the presence or absence of rapamycin. TGF-beta production by activated lymphocytes was quantitated using ELISA.

RESULTS

Splenic leukocytes from BALB/c mice that were primed with allogeneic cells and conditioned with rapamycin in vivo as well as splenic leukocytes that were treated with rapamycin in vitro produced significantly higher levels of TGF-beta upon anti-CD3 stimulation as compared with untreated controls.

CONCLUSION

Our data suggest that rapamycin can program activated lymphocytes to produce TGF-beta. Thus, the immunosuppressive effects of rapamycin may be partially mediated by TGF-beta.