Expression of transforming growth factor-beta 1 and alpha-smooth muscle actin of myofibroblast in the pathogenesis of nasal polyps

The pathophysiology of nasal polyps remains unclear, but recent work suggests that many cytokines are produced in nasal polyps (NPs) and that they may play various important roles in the pathogenesis of NPs. Transforming growth factor-beta 1 (TGF-beta 1), secreted by many inflammatory cells, is a potent inducer of myofibroblasts. Myofibroblasts express alpha-smooth muscle actin (alpha-SMA) and a source of extracellular matrix (ECM). In this study, we investigated a potential link between inflammation and the growth process in human NPs. Sixteen patients who were affected by NPs and who had undergone functional endoscopic sinus surgery were included in this study. Nasal mucosa of inferior turbinate (NM) of 10 patients who had received rhinoplasty or turbinectomy for other disease was used as the control. alpha-SMA and TGF-beta 1 were detected using immunohistochemistry and the number of labeled cells were counted (alpha-SMA and TGF-beta 1 indices). The expression of alpha-SMA and TGF-beta 1 indices found in NPs and NM was compared using Student's t-test. In our study, alpha-SMA and TGF-beta 1 indices were found to be significantly higher in nasal polyps than in nasal mucosa. TGF-beta 1 produced by inflammatory cells can influence the development of myofibroblasts which in turn can induce extracellular matrix accumulation and, therefore, TGF-beta 1 plays a important role in the formation of nasal polyps.     

Effect of castration on extracellular matrix remodeling and angiogenesis of the prostate gland

This study was conducted to evaluate the long term effect of castration on the prostate gland proliferation, extracellular matrix remodeling and angiogenesis. Prostate gland proliferation was assessed by immunolocalization of proliferating cell nuclear antigen (PCNA). The expression level of vascular endothelial growth factor (VEGF), transforming growth factor-beta (TGF-beta) and metaloprotenase-13 (MMP-13) by the prostate gland were assessed by immunohistochemistry and quantitative real-time PCR. The expression of the above mentioned parameters by the prostate gland of mature intact dogs were compared to that of castrated dogs six months post-castration. The results showed that castration induced a remarkable atrophy of the prostate gland which was associated with a highly significant decrease in the PCNA proliferation index. Although TGF-beta protein was immunolocalized to the epithelial and stroma cells of the prostate gland from both intact and castrated dogs, castration induced a significant up-regulation of TGF-beta mRNA expression. VEGF mRNA expression and its encoded protein immunolocalization were decreased significantly by the prostate gland from castrated dogs as compared to that of intact dogs. Castration, on the other hand, resulted in no significant change in MMP-13 mRNA expression despite an effect on its cellular immunolocalization which appeared to be localized to the epithelial and stromal cells of the prostate gland from castrated dogs as compared to epithelial cells of the prostate gland from intact dogs. These results indicated that castration-induced prostate gland regression continued to exert a potent suppressive effect on prostate gland proliferation which might be mediated by the elevated level of TGF-beta. Moreover, the low expression level of VEGF might reflect a reduced blood flow demand by the regressed and growth-dormant prostate after castration.     

Transforming growth factor-beta stimulates vascular endothelial growth factor production by folliculostellate pituitary cells

TGF-beta isoforms are expressed in the anterior pituitary and modulate the growth and function of endocrine pituitary cells. Recently, TGF-beta has been shown to stimulate growth and basic fibroblast growth factor secretion in nonendocrine folliculostellate (FS) pituitary cells. We therefore studied whether the production of FS cell-derived vascular endothelial growth factor (VEGF), the most important regulator of vascular permeability and angiogenesis, is affected by TGF-beta. We observed by RT-PCR that TtT/GF cells, which are FS mouse pituitary tumor cells, synthesize TGF-beta1, -beta2, and -beta3. They also express TGF-beta receptors types 1 and 2, as well as Smad2, Smad3, and Smad4 proteins, which are essential for TGF-betabinding and signaling. Stimulation of TtT/GF cells with either TGF-beta1 or TGF-beta3 induced a rapid translocation of Smad2 into the cell nuclei. Both TGF-beta isoforms dose dependently stimulated VEGF production in TtT/GF cells, but not in lactosomatotroph GH3 cells. Time-course studies and suppression of TGF-beta-induced VEGF production by cycloheximide suggest that TGF-beta induces de novo synthesis of VEGF in folliculostellate cells, which is completely blocked by dexamethasone. In primary rat pituitary cell cultures, TGF-beta1 and -beta3 stimulated VEGF production. TGF-beta stimulation of VEGF production by folliculostellate cells could modulate intrapituitary vascular permeability and integrity as well as angiogenesis in an auto-/paracrine manner.     

子宫内膜息肉中VEGF和TGF-β1表达的特点

目的 探讨子宫内膜息肉(EP)的发生发展与血管内皮细胞生长因子(VEGF)和转化生长因子-β1(TGF-β1)表达的相关性.方法 选择EP患者56例,均行宫腔镜EP切除术(TCRP),切除息肉及周围内膜组织进行常规病理检查及免疫组化染色,测定组织中VEGF和TGF-β1因子的表达.结果 VEGF在息肉组织腺体及间质上的表达均高于周围内膜(P＜0.05).TGF-β1在息肉和周围内膜组织腺体上的表达无统计学差异,在息肉组织间质上的表达高于周围内膜组织(P＜0.05).结论 EP的发生发展可能与TGF-β1、VEGF在EP中的异常表达相关.     

Contrasting effects of triiodothyronine on heat shock protein 27 induction and vascular endothelial growth factor synthesis stimulated by TGF-beta in osteoblasts

In osteoblast-like MC3T3-E1 cells, we recently reported that transforming growth factor-beta (TGF-beta) stimulates the induction of heat shock protein 27 (HSP27). In the present study, we investigated the effects of triiodothyronine (T(3)) on the TGF-beta-stimulated induction of HSP27 and synthesis of vascular endothelial growth factor (VEGF) in these cells. T(3) by itself had little effect on the level of HSP27, however, it significantly reduced the TGF-beta-stimulated HSP27 accumulation in a dose-dependent manner in the range between 1 pM and 100 nM. The TGF-beta-stimulated increase in the level of mRNA for HSP27 was also attenuated by T(3). On the other hand, T(3), which alone stimulated the release of VEGF, more than additively stimulated the TGF-beta-induced VEGF release. T(3) enhanced the TGF-beta-induced increase in the levels of mRNA for VEGF. These results strongly suggest that T(3) has contrasting effects on HSP27 induction and VEGF synthesis induced by TGF-beta in osteoblasts.     

Renal interstitial cells, proteinuria and progression of lupus nephritis: new frontiers for old factors

Interstitial cells, inflammatory-immune cells, tubular cells and endothelial cells of the peritubular capillaries have arisen as possible major players of the nephron damage in lupus nephritis. Increased ICAM-1, Von Willebrand factor, soluble endothelial protein C receptors and decreased ADAMS-13 point to a diffuse vascular damage. Albuminuria elicits a rapid generation of hydrogen peroxide in proximal tubular cells along with nuclear factor-kB activation, endothelin-1 and transforming growth factor (TGF-beta1) upregulation. TGF-beta1 enhances epithelial-to-mesenchymal transdifferentiation. Albuminuria also enhances the expression of macrophage chemotactic protein-1 and macrophage inflammatory protein-1alpha, thus leading to increased interstitial inflammation. TGF-beta1 and thrombospondin-1, a putative activator of TGF-beta, induce apoptosis of peritubular capillaries, as well as of glomerular endothelial cells. All these events can be counteracted by hepatocyte growth factor (HGF), which is expressed by the epithelial tubular cells and stimulates the growth of epithelial cells (mitogen), enhances the motility of epithelial cells (motogen), induces renal epithelial tubule regeneration (morphogen) and enhances angiogenesis (angiogen). The balance between TGF-beta1 and HGF could be a key to define the prognostic value of kidney histopathology at baseline and during follow-up, in lupus nephritis. Therapeutic strategies aiming at altering the biological balance in the patients are at hand to test and prove the experimental evidences.     

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.     

Saturation of, and competition for entry into, the apical secretory pathway

To investigate mechanisms of apical sorting in the secretory pathway of epithelial cells, we expressed varying amounts of the 165 amino acid isoform of vascular endothelial growth factor (VEGF(165)) and transforming growth factor beta1 (TGF-beta1) via replication defective adenoviruses. Apical sorting of both proteins was efficient at low expression levels but saturated or was reversed at high expression levels. High expression levels of TGF-beta1 were effective at competing VEGF(165) out of the apical pathway; however, VEGF(165) did not compete out TGF-beta1. Tunicamycin inhibition experiments showed that the apical polarity of VEGF(165) was independent of N-glycosylation. We conclude that the apical sorting of these two molecules is a saturable, signal-mediated process, involving competition for apical sorting receptors. The sorting of the two proteins does not appear to involve N-glycans as sorting signals, or lectin sorters. The observations are particularly relevant to gene therapy because they demonstrate that overexpression of a transgene can result in undesirable missorting of the encoded protein.     

Transforming growth factor beta induces vascular endothelial growth factor elaboration from pleural mesothelial cells in vivo and in vitro.

Vascular endothelial growth factor (VEGF) increases vascular permeability and is important in pleural effusion formation. In studies using transforming growth factor beta (TGF-beta) to produce pleurodesis, we observed that although TGF-beta was more effective than talc or doxycycline, it induced transient production of large pleural effusions. We hypothesized that TGF-beta stimulates VEGF production in pleural tissues in vivo, and by mesothelial cells in vitro. New Zealand White rabbits (n = 33) were given TGF-beta(2) (1.7 or 5.0 microg), talc (400 mg/kg), doxycycline (10 mg/kg), or buffer intrapleurally. Pleural fluid was collected at 24 h. Intrapleural injection of TGF-beta(2) induced a dose-dependent increase in VEGF production. The pleural fluid VEGF level was 2-fold higher in rabbits given 5.0 microg of TGF-beta(2) than in those given 1.7 microg of TGF-beta(2) and 3-fold higher than in those given buffer. VEGF levels were higher after the injection of TGF-beta(2) than after administration of talc or doxycycline. The pleural fluid VEGF correlated significantly with the volume of pleural effusions (r = 0.79, p < 0.00001). In vitro, TGF-beta(2) stimulated a dose-dependent increase in VEGF production from murine pleural mesothelial cells. At 4 and 24 h, TGF-beta(2), but not talc or doxycycline, induced a significant increase in VEGF, when compared with controls. The mesothelial cell VEGF production was significantly reduced by anti-TGF-beta antibody in the TGF-beta(2), talc, and control (buffer and medium) groups. In conclusion, mesothelial cells are an important source of VEGF. TGF-beta increases the VEGF production by mesothelial cells in vivo and in vitro.     

TGF-beta1, -beta2 and -beta3 cooperate to facilitate tubulogenesis in the explanted quail heart

BACKGROUND: Transforming growth factor-beta (TGF-beta) isoforms have been implicated as both pro- and anti-angiogenic modulators. In this study we addressed the roles of TGF-beta isoforms on coronary tubulogenesis. METHODS: Embryonic (E6) quail ventricular specimens were explanted onto collagen gels allowing endothelial cells to migrate and form vascular tubes. Growth factors and/or neutralizing growth factor antibodies were added to the cultures. Endothelial cells were identified using a quail endothelial cell marker, QH1. Image analysis was used to quantify aggregate tube length. RESULTS: Addition of any isoform (TGF-beta(1), TGF-beta(2) or TGF-beta(3)) virtually prevented tubulogenesis (>95% inhibition), while stimulation of tubulogenesis occurred by adding neutralizing antibodies to TGF-beta(3), but not to TGF-beta(1) or -beta(2). When all three isoforms were added, tubulogenesis was enhanced, indicating the key role of TGF-beta(3). Documentation of the inhibitory effect of TGF-beta isoforms on tubulogenesis is further supported by our experiments in which the marked enhancement of tube formation by bFGF and VEGF was negated when exogenous TGF-beta(1), -beta(2), or -beta(3) were added to the cultures. CONCLUSIONS: (1) TGF-beta(1), -beta(2) and -beta(3) each inhibits angiogenesis; (2) cooperation between the three TGF-beta isoforms and other angiogenic factors is essential for the regulation of normal tubulogenesis and (3) the stimulatory effect of VEGF or bFGF on tubulogenesis is negated by exogenous TGB-betas.     

Vascular endothelial growth factor in acute Kawasaki disease

Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is an important regulator of angiogenesis and blood vessel permeability. Kawasaki disease (KD) is characterized by systemic vasculitis with increased vascular permeability, implying a possible role of VEGF in KD. To elucidate the involvement of VEGF in the pathogenesis of KD, we investigated 30 patients with acute KD, comparing the time course of plasma VEGF levels (n = 123) with clinical symptoms and laboratory findings. Compared with control values, the peak levels of plasma VEGF were significantly elevated (38+/-26 vs 244+/-248 pg/ml, p <0.001). The VEGF levels at the appearance of skin rash and/or edema of hands and feet were also elevated to 176+/-163 pg/ml (p <0.001). In 7 patients (23%), the plasma VEGF levels remained increased after the resolution of the skin rash and peripheral edema. The VEGF levels were independent of gamma globulin therapy and levels of serum albumin and C-reactive protein. We also measured the plasma levels of transforming growth factor-beta1 (TGF-beta1) and tumor necrosis factor alpha, both of which can upregulate VEGF in vitro. The plasma levels of VEGF were highly correlated with those of TGF-beta1 (n = 63, r = 0.73, p <0.001) but not with those of tumor necrosis factor alpha. These findings suggest that the production of VEGF is increased and may be upregulated by TGF-beta1 in acute KD. VEGF may be involved in the hyperpermeability of local blood vessels in acute KD.     

Vascular endothelial growth factor is increased by human pulmonary cells stimulated with Dermatophagoides sp. extract.

Airway remodeling may lead to increased secretion of TGF-beta. TGF-beta is known to activate fibroblasts and to stimulate the secretion of vascular endothelial growth factor (VEGF). Soluble and cell-associated VEGF have been identified in subjects with chronic severe asthma. Dermatophagoides sp. has been shown to contribute to the pathogenesis of asthma. The aim of this study was to determine if the Dermatophagoides sp. extract can stimulate confluent A549 (cA549) to express soluble or cell-associated VEGF and to secrete other factors that stimulate normal human lung fibroblasts (NHLFs) to secrete VEGF. Immunocytochemistry for cell-associated VEGF (pg/mL) was performed on cA549 stimulated with 300, 600, and 1000 AU/mL of dialyzed Dermatophagoides sp. extract for 24 hours with serum-free media (SFM). The subsequent conditioned media (CM) was transferred to NHLF for 24 hours (CM-NHLF). VEGF in CM, CM-NHLF, and control media (CTLM; extract without cA549) were measured by ELISA and normalized to cell density as measured by absorbance of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenol tetrazolium bromide at A550 nm (VEGF pg/mL:A550). Parametric data were analyzed by t-test or ANOVA at alpha = 0.05. Dermatophagoides sp. extract increased normalized VEGF secretion by cA549. Immunochemical VEGF expression by cA549 was increased qualitatively by Dermatophagoides sp. extract. The 1000 CM-NHLF showed increased normalized VEGF relative to CTLM. Dermatophagoides sp. stimulates cA549 to increase soluble and immunochemical VEGF and to secrete mediators that stimulate NHLF to increase secretion of VEGF. This suggests that inhalation of dust-mite allergen may stimulate airway cells to increase VEGF secretion, potentially contributing to edema in airway remodeling.     

Angiopoietins,growth factors,and vascular morphology in early arthritis

OBJECTIVE: To examine angiogenic growth factors in patients with early, untreated inflammatory arthritides and controls. METHODS: Synovial membrane (SM) infiltrate and Ang1, Ang2, and vascular endothelial growth factor (VEGF) mRNA and protein expression were examined using immunohistochemistry and in situ hybridization. Synovial fluid (SF) VEGF, transforming growth factor-beta (TGF-beta 1), and tumor necrosis factor-alpha (TNF-alpha) protein were measured by ELISA. Vascular morphology was assessed at arthroscopy. RESULTS: Ang2 mRNA and protein expression was observed in early psoriatic arthritis (PsA) and rheumatoid arthritis (RA) SM. Expression of Ang2 and VEGF was significantly greater in early PsA SM and correlated strongly. SF VEGF and TGF-beta 1 concentrations were also significantly higher in early PsA compared to RA. Distinct vascular morphology, with tortuous vessels in PsA, correlated with microscopic vascular scores (r = 0.54, p = 0.005) and VEGF levels (r = 0.51, p = 0.01). Ang1 mRNA and protein expression was observed, but concentrations were markedly lower than for Ang2 and VEGF. Clinical disease activity, SM infiltration, and SF TNF-alpha concentrations were similar in both groups. CONCLUSION: This is the first report of angiopoietin expression in early inflammatory arthritis. There is a close relationship between angiopoietins, VEGF, TGF-beta, and vascular morphology. There is differential angiogenesis at an early stage of inflammation, with major pathogenic and therapeutic implications.     

Transforming growth factor beta1 induction of vascular endothelial growth factor receptor 1: mechanism of pericyte-induced vascular survival in vivo

Degeneration of vessels precedes and precipitates the devastating ischemia of many diseases, including retinopathy of prematurity and diabetic retinopathy. Ischemia then leads to proliferative retinopathy and blindness. Understanding the mechanisms of blood vessel degeneration is critical to prevention of these diseases. Vessel loss is associated with oxygen-induced suppression of vascular endothelial growth factor (VEGF) and with pericyte (vascular smooth muscle cell) dropout. The molecular mechanism of pericyte protection of the vasculature is unknown. We show that transforming growth factor beta1 (TGF-beta1)-expressing pericytes are specifically found on vessels resistant to oxygen-induced loss. TGF-beta1 potently induces VEGF receptor 1 (VEGFR-1) expression in endothelial cells and thereby prevents oxygen-induced vessel loss in vivo. Vessel survival is further stimulated with a VEGFR-1-specific ligand, placental growth factor 1. TGF-beta1 induction of VEGFR-1 in endothelial cells explains pericyte protection of vessels and the selective vulnerability of neonatal vessels to oxygen. These results implicate induction and activation of VEGFR-1 as critical targets to prevent vessel loss.     

Diaphragmatic angiogenic growth factor mRNA responses to increased ventilation caused by hypoxia and hypercapnia.

This study investigates the effect of increased ventilation on the expression of messenger ribonucleic acid (mRNA) levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and transforming growth factor-beta1 (TGF-beta1) in the diaphragm of intact, awake, spontaneously breathing rats, compared with responses in paralysed, mechanically-ventilated animals at similar blood gas and ventilatory levels. Four groups of intact, rats were studied in a body box, each group breathing one of four gases: room air, 12% oxygen (O2), 5% carbon dioxide (CO2), or 12% O2+5% CO2 for 1 h. Another 4 groups of paralysed, mechanically-ventilated animals were matched for arterial blood gas and ventilatory level. The results showed that VEGF mRNA abundance was increased three-fold and that of bFGF 1.5-fold when 12% O2+5% CO2 were breathed, but TGF-beta1 did not change. A significant linear relationship of VEGF and bFGF mRNA to minute ventilation was observed in awake animals (r=0.98, p<0.02 and r=0.87, p<0.03, respectively). The paralysed, mechanically-ventilated animals showed no mRNA increases for any probe. Systemic hypoxia had no additional effect on VEGF or bFGF levels in the diaphragm. It was concluded that messenger ribonucleic acid for vascular endothelial growth factor and basic fibroblast growth factor in the diaphragm rises significantly as a result of active ventilation and not due to blood gas/pH changes or to passive muscle shortening per se.