The perichondrium plays an important role in mediating the effects of TGF-beta1 on endochondral bone formation.

Endochondral bone formation is complex and requires the coordination of signals from several factors and multiple cell types. Thus, chondrocyte differentiation is regulated by factors synthesized by both chondrocytes and cells in the perichondrium. Previously, we showed that expression of a dominant-negative form of the transforming growth factor beta (TGF-beta) type II receptor in perichondrium/periosteum resulted in increased hypertrophic differentiation in growth plate chondrocytes, suggesting a role for TGF-beta signaling to the perichondrium in limiting terminal differentiation in vivo. Using an organ culture model, we later demonstrated that TGF-beta1 inhibits chondrocyte proliferation and hypertrophic differentiation by two separate mechanisms. Inhibition of hypertrophic differentiation was shown to be dependent on Parathyroid hormone-related peptide (PTHrP) and expression of PTHrP mRNA was stimulated in the perichondrium after treatment with TGF-beta1. In this report, the hypothesis that the perichondrium is required for the effects of TGF-beta1 on growth and/or hypertrophic differentiation in mouse metatarsal organ cultures is tested. Treatment with TGF-beta1 inhibited expression of type X collagen mRNA in metatarsal cultures with the perichondrium intact. In contrast, hypertrophic differentiation as measured by expression of Type X collagen was not inhibited by TGF-beta1 in perichondrium-free cultures. TGF-beta1 added to intact cultures inhibited BrdU incorporation in chondrocytes and increased incorporation in the perichondrium; however, TGF-beta1 treatment stimulated chondrocyte proliferation in metatarsals from which the perichondrium had been enzymatically removed. These results suggest that the TGF-beta1-mediated regulation of both chondrocyte proliferation and hypertrophic differentiation is dependent upon the perichondrium. Thus, one or several factors from the perichondrium might mediate the way chondrocytes respond to TGF-beta1.     

Enhanced expression of transforming growth factor-beta type I and type II receptors in wound granulation tissue and hypertrophic scar.

In the present study we have analyzed and compared, by immunohistochemistry and in situ hybridization, the expression pattern of the R4/ALK5 transforming growth factor (TGF)-beta type I receptor (RI) and the TGF-beta type II receptor (RII) in normal human skin, in wounded skin at various stages during the transition of wound granulation tissue to scar, and in long-persisting post-burn hypertrophic scars. In normal human skin, expression of RI and RII was clearly visible in the epidermis, in epidermal appendages, and in vascular cells, although only a small number of dermal fibroblasts revealed detectable levels of TGF-beta receptor expression. In contrast, granulation tissue fibroblasts showed strong expression of both TGF-beta receptor types, although in normal-healing excisional wounds their density decreased during granulation tissue remodeling. However, in post-burn hypertrophic scars, RI- and RII-overexpressing fibroblasts were found in high densities up to 20 months after injury. From these findings we suggest that the repair process of deep wounds involves the transformation of a subset of fibroblastic cells toward an increased TGF-beta responsiveness and a transient accumulation of these cells at the wound site. In addition, our study provides evidence that excessive scarring is associated with a failure to eliminate TGF-beta receptor-overexpressing fibroblasts during granulation tissue remodeling, which leads to a persistent autocrine, positive feedback loop that results in over-production of matrix proteins and subsequent fibrosis.     

Inhibition of p38 mitogen-activated protein kinase and transforming growth factor-beta1/Smad signaling pathways modulates the development of fibrosis in adriamycin-induced nephropathy

Inflammation and fibrogenesis are the two determinants of the progression of renal fibrosis, the common pathway leading to end-stage renal disease. The p38 mitogen-activated protein kinase (MAPK) and transforming growth factor (TGF)-beta1/Smad signaling pathways play critical roles in inflammation and fibrogenesis, respectively. The present study examined the beneficial renoprotective effect of combination therapy using the p38 MAPK pathway inhibitor (SB203580) and a TGF-beta receptor I (ALK5) inhibitor (ALK5I) in a mouse model of adriamycin (ADR) nephrosis. The p38 MAPK and TGF-beta1/Smad2 signaling pathways were activated in ADR-induced nephropathy in a sequential time course manner. Two weeks after ADR injection, the combined administration of SB203580 (1 mg/kg/24 hours) and ALK5I (1 mg/kg/24 hours) markedly reduced p38 MAPK and Smad2 activities. Moreover, the co-administration of SB203580 and ALK5I to ADR-injected mice resulted in a down-regulation of total and active TGF-beta1 production, reduced myofibroblast accumulation, and decreased expression of collagen type IV and fibronectin. In these mice, retardation in the development of glomerulosclerosis and interstitial fibrosis was observed. In conclusion, although p38 MAPK and TGF-beta1/Smad signaling pathways are distinct they coordinate the progression of renal fibrosis in ADR nephrosis. The co-administration of a p38 MAPK inhibitor and an ALK5 inhibitor may have potential applications in the treatment of renal fibrosis.     

Signaling hierarchy downstream of retinoic acid that independently regulates vascular remodeling and endothelial cell proliferation

We previously demonstrated that during vascular morphogenesis, retinoic acid (RA) is required for the control of endothelial cell proliferation and capillary plexus remodeling. Herein, we investigate the mechanisms by which RA regulates these processes in the yolk sac. We found that although the enzyme required for RA production during early embryogenesis, retinaldehyde dehydrogenase-2 (Raldh2), was expressed in the visceral endoderm, RA receptors alpha1 and alpha2 were expressed in endothelial cells in the mesoderm, indicating that they are direct targets of RA. In Raldh2(-/-) embryos, there was down-regulation of TGF-beta1, fibronectin (Fn) and integrin alpha5, which was associated with decreased visceral endoderm survival and production of VEGF-A, Indian hedgehog (IHH), and bFGF. Exogenous provision of RA or Fn to Raldh2(-/-) explants in whole mouse embryo culture restored vascular remodeling, visceral endoderm survival, as well as integrin alpha5 expression and its downstream signaling that controls endothelial growth. Exogenous provision of visceral endoderm-derived factors (VEGF-A, IHH, and bFGF) failed to rescue endothelial cell proliferative control but collectively promoted vascular remodeling, suggesting that these processes are independently regulated via a signaling hierarchy downstream of RA.     

Cellular localization of transforming growth factor-beta expression in bleomycin-induced pulmonary fibrosis.

Bleomycin-induced pulmonary fibrosis is associated with increased lung transforming growth factor-beta (TGF-beta) gene expression, but cellular localization of the source of this expression has not been unequivocally established. In this study, lung fibrosis was induced in rats by endotracheal bleomycin injection on day 0 and, on selected days afterwards, lungs were harvested for in situ hybridization, immunohistochemical and histochemical analyses for TGF-beta 1 mRNA and protein expression, and cell identification. The results show that control lungs express essentially no detectable TGF-beta 1 mRNA or protein in the parenchyma. Before day 3 after bleomycin treatment, scattered bronchiolar epithelial cells, mononuclear cells, and eosinophils expressed elevated levels of TGF-beta 1. Between days 3 and 14, there was a major increase in the number of eosinophils, myofibroblasts, and fibroblasts strongly expressing TGF-beta 1 mRNA and protein. TGF-beta 1-producing cells were predominantly localized within areas of injury and active fibrosis. After day 14, the intensity and number of TGF-beta 1-expressing cells significantly declined and were predominantly found in fibroblasts in fibrotic areas. The expression of TGF-beta 1 protein was generally coincident with that for mRNA with the exception of bronchiolar epithelial cells in which strong protein expression was unaccompanied by a commensurate increase in mRNA. The study demonstrates that myofibroblasts, fibroblasts, and eosinophils represent the major sources of increased lung TGF-beta 1 expression in this model of pulmonary fibrosis.     

B-cell chronic lymphocytic leukemia: correlation of clinical stages with angiogenic cytokine expression.

B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of non-cycling B cells in lymphatic and extralymphatic tissues. Earlier studies had validated that angiogenesis was increased in B-CLL. Increased serum concentrations of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) connote a poor prognosis in early-stage B-CLL. Early progression is also related to transforming growth factor-beta (TGF-beta), which inhibits B-cell proliferation and immunoglobulin production. The authors investigated the expression of CD34, VEGF, bFGF, and TGF-beta and their receptors in different stages of B-CLL by analyzing bone marrow samples from 23 patients (11 with Rai stages 0-II; 12 with stages III or IV). TGF-beta2 was expressed more strongly in stages 0 to II than in stages III or IV (P=0.03). There was no significant difference in the intensity of CD34, TGF-beta1, VEGF, and bFGF and their receptors between stages 0 to II and stages III or IV. Staining showed bFGF expression to be stronger than VEGF expression (P=0.001). Results did not confirm an association between the intensity of angiogenesis and B-CLL stage. The expression of TGF-beta2 was stronger in early-stage disease and may help slow disease progression.     

Immunohistochemical study on inducible type of nitric oxide (iNOS), basic fibroblast growth factor (bFGF) and tumor growth factor-beta1 (TGF-beta1) in arteritis induced in rats by fenoldopam and theophylline, vasodilators.

Arteritis induced in rats by vasodilators, fenoldopam and theophylline, was examined immunohistochemically for expressions of inducible type of nitric oxide synthase (iNOS), basic fibroblast growth factor (bFGF) and tumor growth factor-beta1 (TGF-beta1). Rats were administered fenoldopam for 24 hours by intravenous infusion with or without following repeated daily oral administrations of theophylline. Irrespective of theophylline administration, iNOS antigens were remarkably abundant in ED-1-positive cells on day 5 and 8 post-fenoldopam-infusion (DPI); bFGF antigens were remarkably abundant in ED-1-positive cells on 1 and 3 DPI; TGF-beta1 antigens were observed in ED-1-positive cells on and after 5 DPI. These results suggest that the peak expression of iNOS antigen was followed by that of bFGF antigen, and bFGF may have a suppressive effect on iNOS expression in these rat arteritis models. On the other hand, TGF-beta1 was not considered to have a suppressive effect on iNOS expression in these models.     

单侧输尿管梗阻大鼠肾脏岩藻糖基转移酶8的表达变化

目的: 探讨岩藻糖基转移酶8(FUT8)在单侧输尿管梗阻(UUO)大鼠模型肾脏中表达及意义。方法: 90只雄性Wistar 大鼠随机分为正常对照组(control组)、假手术组(sham组)和UUO组,分别在术后1 d、3 d、7 d、14 d和21 d处死,检测各组大鼠肾功能情况;PAS与Masson染色观察大鼠肾间质病理形态学改变;RT-PCR和Western blotting检测各组大鼠肾组织不同时点FUT8 mRNA及蛋白的表达;免疫荧光检测大鼠肾组织不同时点FUT8和活化素受体样激酶5(ALK5)的分布以及表达;免疫组化检测大鼠肾脏纤维连接蛋白(FN)、Ⅰ型胶原(Col I)和α-平滑肌肌动蛋白(α-SMA)表达。结果: 与control组相比,UUO组大鼠血肌酐及尿素氮于术后3 d开始升高(P<0.05),第21 d升至最高(P<0.01);UUO3 d开始肾间质可见明显炎症细胞浸润,14 d出现明显肾小管萎缩,21 d可见明显肾间质纤维化。FUT8的mRNA表达与蛋白水平表达于术后3 d出现上升并随梗阻时间延长逐渐增加(P<0.05),分别于14 d及21 d达到最高峰(P<0.01); ALK5在肾小管的表达与FUT8一致,呈正相关(r=0.87,P<0.05),且两者分布一致,共表达区域随着肾纤维化进展逐渐增加。FN、Col I和α-SMA表达于术后第3 d出现上升并随梗阻时间延长逐渐增加(P<0.05),且与FUT8呈正相关(r=0.80,r=0.76,r=0.89,P<0.05)。结论: 在肾间质纤维化的进展中,FUT8与ALK5表达呈时空一致性升高,可能与肾间质纤维化程度密切相关。     

Expression of p27 and TGF-beta in rat kidney with unilateral ureteral obstruction and the relationship between TGF-beta and p27

AIM: To explore the expression of p27 and the changes of TGF-beta in the renal tubule on the process of renal interstitial fibrosis caused by unilateral ureteral obstruction (UUO) in rats and to investigate the relationship between TGF-beta and p27 in renal interstitial fibrosis rats. METHODS: Sixty rats were randomly divided into sham-operated group (SOR) and UUO group. Ten rats from each group were sacrificed on days 7, 14 and 21 after operation respectively. The renal pathological changes were dynamically observed by HE . The expression and dynamic changes of p27 were detected by immunohistochemistry. The levels of p27 mRNA and TGF-beta mRNA were detected by RT-PCR. RESULTS: The expression of p27 in renal tubular epithelial cells and p27mRNA was strongly positive in SOR group. With the aggravation of interstitial fibrosis, the expression of p27 gradually decreased in UUO group while the expression of TGF-beta increased. There was a negative correlation between TGF-beta and p27. CONCLUSION: P27 is involved in the fibrosis of renal mesenchyme in rats with UUO. The mechanism of TGF-beta accelerating fibrosis may relate to the reduction of p27 expression in UUO rats.     

Keratinocyte-derived growth factors play a role in the formation of hypertrophic scars

In predisposed individuals, wound healing can lead to hypertrophic scar or keloid formation, characterized by an overabundant extracellular matrix. It has recently been shown that hypertrophic scars are accompanied by abnormal keratinocyte differentiation and proliferation, and significantly increased acanthosis, compared with normal scars. This study addressed the question of whether the development of normal and hypertrophic scars is regulated by differences in the growth factor profiles of both the epidermis and the dermis. The presence of interleukin-1alpha (IL-1alpha), IL-1beta, tumour necrosis factor-alpha (TNF-alpha), platelet-derived growth factor (PDGF), transforming growth factor-beta1 (TGF-beta1), and basic fibroblast growth factor (bFGF) was investigated in biopsies taken from breast reduction scars at 3 and 12 months following surgery. The samples were analysed by immunohistological methods and categorized as scars that remained hypertrophic (HH), became normal (HN) or remained normal after 12 months (NN). The epidermal expression of IL-1alpha was significantly increased in NN scars compared with HN and HH scars 3 and 12 months following operation, whereas the dermal expression showed no difference. PDGF was significantly increased in the dermis of normal scars after 3 months and in both the epidermis and the dermis of hypertrophic scars after 12 months. IL-1beta, TNF-alpha, TGF-beta and bFGF showed no differences. It is hypothesized that impaired production of keratinocyte-derived growth factors, such as IL-1alpha, leads to a decrease in the catabolism of the dermal matrix, whereas augmented epidermal PDGF production leads to increased formation of the dermal matrix in hypertrophic scars. These observations support the possibility that the epidermis is involved in preventing the formation of hypertrophic scars.     

Peripheral chondrosarcoma progression is accompanied by decreased Indian Hedgehog signalling

Hedgehog (HH) signalling is important for specific developmental processes, and aberrant, increased activity has been described in various tumours. Disturbed HH signalling has also been implicated in the hereditary syndrome, Multiple Osteochondromas. Indian Hedgehog (IHH), together with parathyroid hormone-like hormone (PTHLH), participates in the organization of growth plates in long bones. PTHLH signalling is absent in osteochondromas, benign tumours arising adjacent to the growth plate, but is reactivated when these tumours undergo malignant transformation towards secondary peripheral chondrosarcoma. We describe a gradual decrease in the expression of Patched (PTCH) and glioma-associated oncogene homologue 1 (GLI1) (both transcribed upon IHH activity), and GLI2 with increasing malignancy, suggesting that IHH signalling is inactive and PTHLH signalling is IHH independent in secondary peripheral chondrosarcomas. cDNA expression profiling and immunohistochemical studies suggest that transforming growth factor-beta (TGF-beta)-mediated proliferative signalling is active in high-grade chondrosarcomas since TGF-beta downstream targets were upregulated in these tumours. This is accompanied by downregulation of energy metabolism-related genes and upregulation of the proto-oncogene jun B. Thus, the tight regulation of growth plate organization by IHH signalling is still seen in osteochondroma, but gradually lost during malignant transformation to secondary peripheral chondrosarcoma and subsequent progression. TGF-beta signalling is stimulated during secondary peripheral chondrosarcoma progression and could potentially regulate the retained activity of PTHLH.     

Transforming growth factor-beta receptors in self-limited vs. chronic progressive nephritis in rats

Increases in transforming growth factor-beta (TGF-beta) expression and extracellular matrix accumulation are transient in acute self-limited mesangial proliferative glomerulonephritis induced by a single injection of anti-thymocyte serum (ATS), while these increases persist following repeated injections that produce chronic progressive sclerosing glomerulonephritis with tubulointerstitial lesions. However, little is known about the expression of TGF-beta receptors (TbetaRs) in cells involved in the proliferative and sclerosing renal lesions. A study of protein and mRNA expression for type I (TbetaRI), type II (TbetaRII), and type III (TbetaRIII) TbetaR in both forms of nephritis was therefore carried out by immunohistochemistry and in situ hybridization. Inhibition of cell proliferation and stimulation of matrix production by TGF-beta1 were assessed in isolated glomeruli using [(3)H]thymidine incorporation and [(3)H]proline metabolic labelling, respectively. In acute self-limited nephritis, expression of TbetaRI, TbetaRII, and TbetaRIII increased in the glomerular and Bowman's capsular epithelial cells comprising the glomerular tuft adhesions to Bowman's capsules. However, TbetaRII expression was not prominent in proliferating mesangial cells. Glomeruli isolated from rats with acute self-limited nephritis at day 7, when mesangial cell proliferation was maximal, were partially resistant to the mitoinhibitory effects of TGF-beta1. In contrast, expression of all three TbetaRs was elevated in glomerular and tubulointerstitial lesions in chronic progressive nephritis, and glomeruli isolated from rats with chronic progressive nephritis 7 days after the second ATS injection were sensitive to TGF-beta1. These data suggest that distinct cellular responses to TGF-beta1 resulting from differential expression of TbetaR underlie the difference between acute self-limited mesangial proliferative and chronic progressive sclerosing ATS nephritis in the development of proliferative and sclerotic renal lesions.     

Endothelial growth factors VEGF and bFGF differentially enhance monocyte and neutrophil recruitment to inflammation

Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are produced at sites of inflammation. Previously, we demonstrated that bFGF enhances leukocyte recruitment and endothelial cell adhesion molecule (CAM) expression during inflammation. Here, we investigated the influence of VEGF during acute inflammation and whether VEGF and bFGF cooperate to modulate leukocyte recruitment. Inflammation was induced in skin of rats by intradermal injection of inflammatory stimuli +/- VEGF +/- bFGF. Migration of 51Cr-monocytes and 111In-polymorphonuclear leukocytes (PMN) to the dermal lesions and 125I-anti-CAM monoclonal antibody binding to the dermal vasculature were quantitated after 2 h. VEGF significantly enhanced tumor necrosis factor alpha (TNF-alpha)-induced monocyte recruitment by 39 +/- 16% and increased P-selectin, E-selectin, and intercellular CAM-1 expression by two- to threefold over TNF-alpha alone. However, recruitment of monocytes to TNF-alpha + interferon-gamma (IFN-gamma) and of PMN to all stimuli tested was not affected by VEGF. In contrast, bFGF enhanced recruitment of both leukocyte types to all stimuli tested. With the potent TNF-alpha + IFN-gamma stimulus, in contrast to bFGF, VEGF did not enhance E-selectin or ICAM-1 expression. bFGF, but not VEGF, increased the chemotactic activity for PMN in TNF-alpha + IFN-gamma-inflamed sites by 54%. The limited effect of VEGF on these mechanisms likely contributed to the differential effect of VEGF and bFGF on leukocyte recruitment. However, VEGF + bFGF increased PMN recruitment more than did either factor alone. Thus, bFGF and VEGF differentially but synergistically enhance leukocyte recruitment to inflammatory stimuli and individually as well as jointly function as positive regulators of inflammatory cell recruitment.     

Immunohistochemical expression of angiogenic cytokines and their receptors in reactive benign lymph nodes and non-Hodgkin lymphoma

Angiogenic cytokines regulate B-cell lymphopoiesis and are related to prognosis in B-cell lymphoproliferative disorders. Transforming growth factor-beta (TGF-beta) inhibits mature B-cell proliferation and immunoglobulin production. Increased levels of serum vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are associated with poor prognosis in non-Hodgkin lymphoma (NHL). To understand the expression of angiogenic cytokines at different stages of B-cell differentiation in lymph nodes, we examined the immunohistochemical expression of TGF-beta, VEGF, bFGF, and their receptors in five patients with reactive benign lymphadenopathy and 12 patients with B-cell NHL (mantle cell lymphoma, 4; small cleaved cell follicular lymphoma, 5; lymphoplasmacytic lymphoma, 3). In benign lymph nodes, TGF-beta1, TGF-beta2, and TGFbetaRII were positive in prefollicular mantle cells, follicular center cells, and postfollicular plasma cells. Basic FGF, FGF-R1, and FGF-R4 were positive in large follicular center cells and postfollicular plasma cells. Vascular endothelial growth factor was positive in large follicular center cells and postfollicular plasma cells. In NHL, TGF-beta and its receptors were weakly positive in small cleaved cell follicular lymphoma; VEGF was strongly positive in lymphoplasmacytic lymphoma and weakly positive in mantle cell lymphoma. Basic FGF and its receptors were negative in NHL; however, FGF-R4 was positive in some cases of small cleaved cell follicular lymphoma. Our findings suggest that TGF-beta, bFGF, and their receptors have opposite roles in B-cell differentiation and maturation in benign lymph nodes. Transforming growth factor-beta and its receptors have an important role in germinal center development; loss of their activity could be associated with abnormal clonal proliferation of NHL.     

Inhibition of activin receptor-like kinase 5 attenuates bleomycin-induced pulmonary fibrosis

Activin receptor-like kinase 5 (ALK5) is a type I receptor of transforming growth factor (TGF)-beta. ALK5 inhibition has been reported to attenuate the tissue fibrosis including pulmonary fibrosis, renal fibrosis and liver fibrosis. To elucidate the inhibitory mechanism of ALK5 inhibitor on pulmonary fibrosis in vivo, we performed the histopathological assessment, gene expression analysis of extracellular matrix (ECM) genes and immunohistochemistry including receptor-activated Smads (R-Smads; Smad2/3), CTGF, myofibroblast marker (alpha-smooth muscle actin; aSMA) and type I collagen deposition in the lung using Bleomycin (BLM)-induced pulmonary fibrosis model. ALK5 inhibitor, SB-525334 (10 mg/kg or 30 mg/kg) was orally administered at twice a day. Lungs were isolated 5, 7, 9 and 14 days after BLM treatment. BLM treatment led to significant pulmonary fibrotic changes accompanied by significant upregulation of ECM mRNA expressions, Smad2/3 nuclear translocation, CTGF expression, myofibroblast proliferation and type I collagen deposition. SB-525334 treatment attenuated the histopathological alterations in the lung, and significantly decreased the type I and III procollagen and fibronectin mRNA expression. Immunohistochemistry revealed that SB-525334 treatment showed significant attenuation in Smad2/3 nuclear translocation, decrease in CTGF-expressing cells, myofibroblast proliferation and type I collagen deposition. These results suggest that ALK5 inhibition attenuates R-Smads activation thereby attenuates pulmonary fibrosis.     

In vitro studies on clonal growth of chondrocytes in thanatophoric dysplasia

Thanatophoric dysplasia (TD) is characterized by a disorganized growth plate with markedly reduced proliferative and hypertrophic cartilage zones. Therefore, we studied in vitro the proliferation rates of articular chondrocytes from five TD patients and age-matched controls in response to bFGF, IGF-I, IGF-II, and TGF-β1. In human fetal controls bFGF was the most potent growth factor. Clonal growth of articular chondrocytes in response to bFGF was reduced in two of five TD patients and slightly below the range of controls in a third case. Stimulation of chondrocyte proliferation by IGF I and II was reduced in the patient whose response to bFGF was most markedly impaired. The effect of TGF-β1 ranged from normal to slightly elevated values in TD fetuses. These results indicate heterogeneity of the underlying defects in TD. Low proliferative responses of chondrocytes to bFGF and IGF-I/II are likely to play a key role in the pathogenesis of some cases. In two of five patients studied, the mechanisms of bFGF and IGF-signal transduction are candidates for the primary molecular defect. © 1996 Wiley-Liss, Inc.