Proinflammatory cytokines (interleukin-1 beta and tumor necrosis factor-alpha) down regulate synthesis and secretion of thrombospondin by human endothelial cells

Direct antitumoral effects of sulfated fucans isolated from echinoderms: a possible role of neuropilin-1/β1 integrin endocytosis and focal adhesion kinase degradation

Hypercoagulability, a major complication of metastatic cancers, has usually been treated with heparins from natural sources, or with their synthetic derivatives, which are under intense investigation in clinical oncology. However, the use of heparin has been challenging for patients with risk of severe bleeding. While the systemic administration of heparins, in preclinical models, has shown primarily attenuating effects on metastasis, their direct effect on established solid tumors has generated contradictory outcomes. We investigated the direct antitumoral properties of two sulfated fucans isolated from marine echinoderms, FucSulf1 and FucSulf2, which exhibit anticoagulant activity with mild hemorrhagic potential. Unlike heparin, sulfated fucans significantly inhibited tumor cell proliferation (by ~30-50%), and inhibited tumor migration and invasion in vitro. We found that FucSulf1 and FucSulf2 interacted with fibronectin as efficiently as heparin, leading to loss of prostate cancer and melanoma cell spreading. The sulfated fucans increased the endocytosis of β1 integrin and neuropilin-1 chains, two cell receptors implicated in fibronectin-dependent adhesion. The treatment of cancer cells with both sulfated fucans, but not with heparin, also triggered intracellular focal adhesion kinase (FAK) degradation, with a consequent overall decrease in activated focal adhesion kinase levels. Finally, only sulfated fucans inhibited the growth of B16-F10 melanoma cells implanted in the dermis of syngeneic C57/BL6 mice. FucSulf1 and FucSulf2 arise from this study as candidates for the design of possible alternatives to long-term treatments of cancer patients with heparins, with the advantage of also controlling local growth and invasion of malignant cells.

FGF7/FGFR2 signal promotes invasion and migration in human gastric cancer through upregulation of thrombospondin-1

Fibroblast growth factor 7 (FGF7) is a mesenchyme-specific heparin-binding growth factor that binds FGF receptor 2 (FGFR2) to regulate numerous cellular and physiological processes. FGF7/FGFR2 signal is associated with gastric cancer progression. In the present study, we investigated the molecular mechanism by which FGF7/FGFR2 promotes invasion and migration in human gastric cancer. We first demonstrated that increased FGFR2 expression in human gastric cancer tissues was significantly associated with tumor depth and clinical stage in human gastric cancer tissues. Thrombospondin 1 (THBS1) is an extracellular glycoprotein that plays multiple roles in cell-matrix and cell-cell interactions. Increased expression of THBS1 significantly correlated with tumor differentiation. FGFR2 and THBS1 expression were both increased in cancer tissues as compared with adjacent normal tissues and their expression was positively correlated. In vitro, FGF7 stimulation of cell invasion and migration was partially suppressed by the FGFR2 knockdown. In addition, FGF7/FGFR2 upregulated THBS1, and cell invasion and migration were decreased by knockdown of THBS1. Furthermore, the PI3K/Akt/mTOR signaling pathway was predominantly responsible for FGF7/FGFR2-induced THBS1 upregulation. Taken together, our data suggest that FGF7/FGFR2/THBS1 is associated with the regulation of invasion and migration in human gastric cancer.

Obesity modifies bone marrow microenvironment and directs bone marrow mesenchymal cells to adipogenesis

OBJECTIVE

To investigate the role of obesity on the bone marrow microenvironment and evaluate its possible impact on the adipogenic potential of mesenchymal stem cells (MSC).

METHODS

C57BL/6 male mice were fed with a high-fat diet (HFD) for 10 weeks. Femurs and tibiae were collected, and bone marrow mesenchymal stem cells (BM-MSC) were isolated and analyzed for proliferative potential, immunophenotype, and expression of adipogenesis markers. Their capacity to produce extracellular matrix proteins and proinflammatory cytokines in vitro was also evaluated.

RESULTS

HFD mice presented a significant increase in bone marrow cellularity and higher tumor necrosis factor-α production in vitro. BM-MSC from HFD mice had higher proliferative capacity, produced more extracellular matrix proteins associated with adipogenesis, collagen I, and collagen IV, and showed increased constitutive expression of adipogenic markers, peroxisome proliferator-activated receptor-γ, and CCAAT/enhanced binding protein family-α, without changes in preadipocyte factor-1 expression. Incubation with adipocyte-differentiation medium induced further increase in CCAAT/enhanced binding protein family-α and augmented adiponectin expression in obese BM-MSC. These alterations did not result in increased adipogenic differentiation within the bone marrow. Moreover, BM-HSC from HFD mice, co-cultivated with BM-MSCs from lean mice, exerted paracrine effects on these cells, inducing augment of peroxisome proliferator-activated receptor-γ.

CONCLUSIONS

The data suggest that obesity promotes an inflammatory microenvironment in bone marrow that commits BM-MSC to adipogenesis.

Hantavirus Infection Suppresses Thrombospondin-1 Expression in Cultured Endothelial Cells in a Strain-Specific Manner

Hantavirus infection is associated with two frequently fatal diseases in humans: Hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). The pathogenesis of hantavirus infection is complex and not fully understood; however, it is believed to involve virus-induced hyperinflammatory immune responses. Thrombospondin-1 (THBS1) is a large homotrimeric protein that plays a putative role in regulating blood homeostasis. Hyperresponsiveness to inflammatory stimuli has also been associated with defects in the THBS1 gene. Our data suggest that hantavirus infection of human umbilical cord vein endothelial cells (HUVEC) suppress the accumulation of THBS1 in the extracellular matrix. Additionally, this suppression is dependent on virus replication, implying a direct mechanism of action. Our data also imply that the pathogenic Andes and Hantaan strains inhibit THBS1 expression while the non-pathogenic Prospect Hill strain showed little inhibition. These observations suggest that a dysregulation of THBS1 may contribute to the pathogenesis of hantavirus infection.

Tissue factor inflammatory response regulated by promoter genotype and p38 MAPK in neonatal vs. adult microvascular endothelial cells

OBJECTIVE AND DESIGN

Variable tissue factor (TF) expression by human microvascular endothelial cells (HMVEC) may be regulated by two promoter haplotypes, distinguished by an 18-basepair deletion (D) or insertion (I) at -1,208. We sought to determine the relationship between these haplotypes and interleukin-1α (IL-1α)-induced TF expression in neonatal versus adult HMVEC.

RESULTS

IL-1-stimulated TF mRNA, protein, and activity were significantly higher in neonatal compared to adult D/D donors. IL-1-stimulated HMVEC from neonatal D/D donors expressed threefold higher levels of TF mRNA, twofold higher TF protein, and fourfold increased TF activity compared to HMVEC from adult D/D donors. These results indicate that homozygosity for the D haplotype is characterized by increased response to IL-1 in neonates, but not adults. IL-1 induced increased phosphorylation of p38 mitogen-activated protein kinase (MAPK), which was significantly greater in neonatal compared to adult HMVEC. Moreover, inhibition of the p38 MAPK pathway reduced IL-1-stimulated TF mRNA expression in D/D neonatal but not adult HMVEC.

CONCLUSIONS

Upregulation of D/D neonatal HMVEC TF expression by IL-1 is mediated through the p38 MAPK pathway. This heightened response of D/D neonatal HMVEC to inflammatory stimuli may contribute to increased microvascular coagulopathies in susceptible newborn infants.

Thrombospondin 1 mediates renal dysfunction in a mouse model of high-fat diet-induced obesity

Obesity is prevalent worldwide and is a major risk factor for many diseases including renal complications. Thrombospondin 1 (TSP1), a multifunctional extracellular matrix protein, plays an important role in diabetic kidney diseases. However, whether TSP1 plays a role in obesity-related kidney disease is unknown. In the present studies, the role of TSP1 in obesity-induced renal dysfunction was determined by using a diet-induced obese mouse model. The results demonstrated that TSP1 was significantly upregulated in the kidney from obese mice. The increased TSP1 was localized in the glomerular mesangium as well as in the tubular system from obese wild-type mice. Obese wild-type mice developed renal hypertrophy and albuminuria, which was associated with increased kidney macrophage infiltration, augmented kidney inflammation, and activated transforming growth factor (TGF)-β signaling and renal fibrosis. In contrast, obese TSP1-deficient mice did not develop these kidney damages. Furthermore, in vitro studies demonstrated that leptin treatment stimulated the expression of TSP1, TGF-β1, fibronectin, and collagen type IV in mesangial cells isolated from wild-type mice. These leptin-stimulated effects were abolished in TSP1-deficient mesangial cells. Taken together, these data suggest that TSP1 is an important mediator for obesity- or hyperleptinemia-induced kidney dysfunction.

Matricellular proteins in cardiac adaptation and disease

The term matricellular proteins describes a family of structurally unrelated extracellular macromolecules that, unlike structural matrix proteins, do not play a primary role in tissue architecture, but are induced following injury and modulate cell-cell and cell-matrix interactions. When released to the matrix, matricellular proteins associate with growth factors, cytokines, and other bioactive effectors and bind to cell surface receptors transducing signaling cascades. Matricellular proteins are upregulated in the injured and remodeling heart and play an important role in regulation of inflammatory, reparative, fibrotic and angiogenic pathways. Thrombospondin (TSP)-1, -2, and -4 as well as tenascin-C and -X secreted protein acidic and rich in cysteine (SPARC), osteopontin, periostin, and members of the CCN family (including CCN1 and CCN2/connective tissue growth factor) are involved in a variety of cardiac pathophysiological conditions, including myocardial infarction, cardiac hypertrophy and fibrosis, aging-associated myocardial remodeling, myocarditis, diabetic cardiomyopathy, and valvular disease. This review discusses the properties and characteristics of the matricellular proteins and presents our current knowledge on their role in cardiac adaptation and disease. Understanding the role of matricellular proteins in myocardial pathophysiology and identification of the functional domains responsible for their actions may lead to design of peptides with therapeutic potential for patients with heart disease.

Characterization of synovial angiogenesis in osteoarthritis patients and its modulation by chondroitin sulfate

Introduction

This work aimed at comparing the production of inflammatory and pro- and anti-angiogenic factors by normal/reactive (N/R) or inflammatory (I) areas of the osteoarthritic synovial membrane. The effects of interleukin (IL)-1β and chondroitin sulfate (CS) on the expression of pro- and anti-angiogenic factors by synovial fibroblasts cells (SFC) were also studied.

Methods

Biopsies from N/R or from I areas of osteoarthritic synovial membrane were collected at the time of surgery. The inflammatory status of the synovial membrane was characterized by the surgeon according to macroscopic criteria, including the synovial vascularization, the villi formation and the hypertrophic aspect of the tissue. We assessed the expression of CD45, von Willebrand factor and vascular endothelial growth factor (VEGF) antigen by immunohistochemistry in both N/R and I biopsies. The production of IL-6, -8, VEGF and thrombospondin (TSP)-1 by N/R or I synovial cells was quantified by ELISA. SFC were cultured in the absence or in the presence of IL-1β (1 ng/ml) and with or without CS (10, 50, 200 μg/ml). Gene expression of pro-angiogenic factors (VEGF, basic fibroblast growth factor (bFGF), nerve growth factor (NGF), matrix metalloproteinase (MMP)-2 and angiopoietin (ang)-1) and anti-angiogenic factors (vascular endothelial growth inhibitor (VEGI), TSP-1 and -2) were determined by real time RT-PCR. Production of VEGI and TSP-1 was also estimated by ELISA.

Results

Immunohistochemistry showed the increase of lymphocyte infiltration, vascular density and VEGF expression in I compared to N/R synovial biopsies. Synovial cells from I areas produced more IL-6, IL-8 and VEGF but less TSP-1 than cells isolated from N/R synovial biopsies. The expression of pro-angiogenic factors by SFC was stimulated by IL-1β. A time dependent regulation of the expression of anti-angiogenic factor genes was observed. IL-1β stimulated the expression of anti-angiogenic factor genes but inhibited it after 24 h. CS reversed the inhibitory effect of IL-1β on anti-angiogenic factors, VEGI and TSP-1.

Conclusions

We demonstrated that synovial biopsies from I areas expressed a pro-angiogenic phenotype. IL-1β induced an imbalance between pro- and anti-angiogenic factors in SFC and CS tended to normalize this IL-1β-induced imbalance, providing a new possible mechanism of action of this drug.

Therapies using anti-angiogenic peptide mimetics of thrombospondin-1

INTRODUCTION

The role of hrombospondin-1 (TSP1) as a major endogenous angiogenesis inhibitor has been confirmed by numerous studies and subsequent mechanistic discoveries. It has yielded a new class of potential drugs against cancer and other angiogenesis-driven diseases.

AREAS COVERED

An overview of TSP1 functions and molecular mechanisms, including regulation and signaling. Functions in endothelial and non-endothelial cells, with emphasis on the role of TSP1 in the regulation of angiogenesis and inflammation. The utility of duplicating these activities for drug discovery. Past and current literature on endogenous TSP1 and its role in the progression of cancer and non-cancerous pathological conditions is summarized, as well as the research undertaken to identify and optimize short bioactive peptides derived from the two TSP1 anti-angiogenic domains, which bind CD47 and CD36 cell surface receptors. Lastly, there is an overview of the efficacy of some of these peptides in pre-clinical and clinical models of angiogenesis-dependent disease.

EXPERT OPINION

It is concluded that TSP1-derived peptides and peptide mimetics hold great promise as future agents for the treatment of cancer and other diseases driven by excessive angiogenesis. They may fulfill unmet medical needs including neovascular ocular disease and the diseases of the female reproductive tract including ovarian cancer.

Role of JNK/ATF-2 pathway in inhibition of thrombospondin-1 (TSP-1) expression and apoptosis mediated by doxorubicin and camptothecin in FTC-133 cells

Our previous studies have shown that camptothecin and doxorubicin triggered ceramide accumulation via de novo synthesis pathway. De novo ceramide generation was responsible for the drug-induced apoptosis through a caspase-3-dependent pathway and a decrease of thrombospondin-1 expression in human thyroid carcinoma FTC-133 cells. Here, we demonstrate that Jun N-terminal kinases play a critical role in camptothecin- and doxorubicin-induced down-regulation of thrombospondin-1 expression: i) de novo ceramide synthesis pathway activates Jun N-terminal kinase 1/2 resulting in activating transcription factor 2 phosphorylation; ii) cell treatment by SP600125, a Jun N-terminal kinase specific inhibitor, strongly reduced activating transcription factor 2 phosphorylation and completely abolished camptothecin and doxorubicin effects; and iii) activating transcription factor 2 expression silencing greatly attenuated camptothecin- and doxorubicin-induced down-regulation of thrombospondin-1 expression and apoptosis. The set of our data established that camptothecin- and doxorubicin-induced activation of Jun N-terminal kinase/activating transcription factor 2 pathway via de novo ceramide synthesis down-regulates thrombospondin-1 expression and apoptosis in human thyroid carcinoma FTC-133 cells. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.

Differential modulation of adhesion molecule expression by hydroxycarbamide in human endothelial cells from the micro- and macrocirculation: potential implications in sickle cell disease vasoocclusive events

BACKGROUND

All the cellular partners of the vascular system and especially endothelial cells are involved in the pathophysiology of the vasoocclusive crises associated with sickle cell disease. In sickle cell disease, circulating cells adhere abnormally to endothelial cells in a chronic pro-inflammatory context. Hydroxycarbamide is the only drug with demonstrated efficacy to reduce the frequency of vasoocclusive crises. Here, we investigated the effects of hydroxycarbamide and/or cytokines on the expression of genes related to adhesion events in endothelial cells from three different vascular sites.

DESIGN AND METHODS

Endothelial cells representative of the macro- (HUVEC) or microcirculation (TrHBMEC and HPMEC) were grown in the presence or absence of hydroxycarbamide and/or cytokines (TNFα and IFNγ). Expression of genes encoding adhesion proteins was analyzed by RQ-PCR, ELISA, flow cytometry, in situ ELISA for extracellular matrix proteins, and Western blot.

RESULTS

In cells from the microcirculation, expression of TSP-1, vWF, and PECAM-1 genes was decreased by hydroxycarbamide and/or cytokine treatment at the mRNA level. In the macro-circulation their expression was unaffected or increased. Hydroxycarbamide significantly decreased vWF incorporated in the TrHBMEC extracellular matrix. CD36 mRNA was strongly down-regulated by cytokines in HPMEC, the only cell type in which it is expressed. Hydroxycarbamide decreased soluble PECAM-1 in HUVEC supernatants.

CONCLUSIONS

Our results highlight the heterogeneity of vascular endothelial cell responses to hydroxycarbamide and/or cytokines depending upon their origin. They also suggest that hydroxycarbamide has an anti-adhesogenic effect on endothelial cells, but by mechanisms which could vary according to their macro- or microcirculation and organ origin.

TGF-beta1 induces transendothelial migration of the pathogenic fungus Sporothrix schenckii by a paracellular route involving extracellular matrix proteins

Sporotrichosis, a mycosis caused by Sporothrix schenckii, is characterized by lymphocutaneous lesions. In immunocompromised hosts, this fungus may invade the bloodstream and disseminate to other tissues, such as lung and bone. Our group previously showed that S. schenckii yeasts adhere to endothelial monolayers and that this interaction is modulated by cytokines. Using 3.0 mum-pore culture inserts, the present work shows that transforming growth factor (TGF)-beta1 led to a 80+/-26 % increase in fungal migration across endothelial monolayers and inhibited fungus internalization by 55+/-23.5 %, when compared to untreated cells. The major surface endothelial molecules recognized by S. schenckii were not modulated by TGF-beta1. These data suggested that a paracellular route is preferentially used by S. schenckii during the transmigration of cultured endothelial cells. It was further observed that TGF-beta1 increased the subendothelial matrix exposure and that anti-fibronectin (anti-FN) and anti-laminin (anti-LM) antibodies abolished the increase in S. schenckii association with endothelial monolayers induced by TGF-beta1. These antibodies also inhibited (38.2+/-4.29 % and 50.8+/-17.3 %, respectively) the adhesion of S. schenckii to freshly prepared native endothelial matrices. Furthermore, transendothelial migration of S. schenckii was blocked by anti-FN and anti-LM antibodies. These data indicate that TGF-beta1-induced S. schenckii adhesion to endothelial monolayers results from the increased exposure of the subendothelial extracellular matrix and that this event may contribute to the enhancement of transendothelial migration.

Activating Transcription Factor-1-mediated Hepatocyte Growth Factor-induced Down-regulation of Thrombospondin-1 Expression Leads to Thyroid Cancer Cell Invasion

Hepatocyte growth factor (HGF) plays a major role in the pathogenesis of a variety of human epithelial tumors including papillary carcinoma of the thyroid. Previous reports demonstrated that HGF, acting through the Met receptor, repressed thrombospondin-1 (TSP-1) expression. To study the mechanisms by which HGF down-regulated TSP-1 expression, we transiently transfected a panel of deleted human TSP-1 promoter reporter plasmids into papillary thyroid carcinoma cells. We identified a region between -1210 and -1123 bp relative to the transcription start site that is responsive to HGF treatment and harbors a cAMP-responsive element (CRE) at position -1199 (TGACGTCC). Overexpression of various members of the CRE-binding protein family identified activating transcription factor-1 (ATF-1) as the transcription factor responsible for HGF-induced repression of TSP-1 promoter activity. This inhibition was associated with a concomitant increase in the abundance of nuclear ATF-1 protein. Gel shift and antibody supershift studies indicated that ATF-1 was involved in DNA binding to the TSP-1-CRE site. Finally, we utilized small hairpin RNA to target ATF-1 and showed that these small interfering RNA constructs significantly inhibited ATF-1 expression at both the RNA and the protein level. ATF-1 knockdown prevented HGF-induced down-regulation of TSP-1 promoter activity and protein expression and also reduced HGF-dependent tumor cell invasion. Taken together, our results indicate that HGF-induced down-regulation of TSP-1 expression is mediated by the interaction of ATF-1 with the CRE binding site in the TSP-1 promoter and that this transcription factor plays a crucial role for tumor invasiveness in papillary carcinoma of the thyroid triggered by HGF.

Thrombospondin-1 up-regulates expression of cell adhesion molecules and promotes monocyte binding to endothelium

Expression of cell adhesion molecules (CAM) responsible for leukocyte-endothelium interactions plays a crucial role in inflammation and atherogenesis. Up-regulation of vascular CAM-1 (VCAM-1), intracellular CAM-1 (ICAM-1), and E-selectin expression promotes monocyte recruitment to sites of injury and is considered to be a critical step in atherosclerotic plaque development. Factors that trigger this initial response are not well understood. As platelet activation not only promotes thrombosis but also early stages of atherogenesis, we considered the role of thrombospondin-1 (TSP-1), a matricellular protein released in abundance from activated platelets and accumulated in sites of vascular injury, as a regulator of CAM expression. TSP-1 induced expression of VCAM-1 and ICAM-1 on endothelium of various origins, which in turn, resulted in a significant increase of monocyte attachment. This effect could be mimicked by a peptide derived from the C-terminal domain of TSP-1 and known to interact with CD47 on the cell surface. The essential role of CD47 in the cellular responses to TSP-1 was demonstrated further using inhibitory antibodies and knockdown of CD47 with small interfering RNA. Furthermore, we demonstrated that secretion of endogenous TSP-1 and its interaction with CD47 on the cell surface mediates endothelial response to the major proinflammatory agent, tumor necrosis factor alpha (TNF-alpha). Taken together, this study identifies a novel mechanism regulating CAM expression and subsequent monocyte binding to endothelium, which might influence the development of anti-atherosclerosis therapeutic strategies.

Critical Role of Endogenous Thrombospondin-1 in Preventing Expansion of Healing Myocardial Infarcts

Background— Matricellular proteins are extracellular matrix proteins that do not contribute directly to tissue integrity but are capable of modulating cell function. We hypothesized that the matricellular protein thrombospondin (TSP)-1, a potent inhibitor of angiogenesis and activator of transforming growth factor (TGF-β), is induced in healing myocardial infarcts and plays a role in suppressing the postinfarction inflammatory response, inhibiting local angiogenesis, and limiting expansion of granulation tissue into the noninfarcted area.

Methods and Results— We used a canine and a murine model of reperfused infarction. TSP-1 mRNA was induced in canine infarcts after 1 hour of ischemia and 3 to 7 days of reperfusion. TSP-1 protein showed a strikingly selective localization in the extracellular matrix, microvascular endothelium, and a subset of mononuclear cells of the infarct border zone after 5 to 28 days of reperfusion. Isolated canine venous endothelial cells showed low-level constitutive expression of TSP-1 mRNA, which was markedly induced by TGF-β, and basic fibroblast growth factor. Murine infarcts also had marked TSP-1 deposition in the border zone. Infarcted TSP-1 −/− mice exhibited sustained upregulation of the chemokines monocyte chemoattractant protein-1, macrophage inflammatory protein-1α, and interferon-γ–inducible protein-10/CXCL10 and the cytokines interleukin-1β, interleukin-6, and TGF-β, suggesting an enhanced and prolonged postinfarction inflammatory response. In addition, TSP-1 −/− mice had markedly increased macrophage and myofibroblast density in infarcts and in remodeling noninfarcted myocardial areas neighboring the myocardial scar, suggesting expansion of granulation tissue formation into the noninfarcted territory. TSP-1 −/− animals had more extensive postinfarction remodeling than wild-type mice, although infarct size was similar in both groups.

Conclusions— The infarct border zone may be capable of modulating the healing process through its unique extracellular matrix content. The selective endogenous expression of TSP-1 in the infarct border zone may serve as a “barrier,” limiting expansion of granulation tissue and protecting the noninfarcted myocardium from fibrotic remodeling.

Human guanylate binding protein-1 (hGBP-1) characterizes and establishes a non-angiogenic endothelial cell activation phenotype in inflammatory diseases

Blood vessel activation in inflammatory diseases is triggered by a myriad of different factors that partially reveal opposite activities on endothelial cells (EC). For example, inflammatory cytokines (IC) inhibit EC proliferation and induce cell adhesiveness for leukocytes. In contrast, angiogenic growth factors (AGF) activate EC proliferation and inhibit cell adhesiveness for leukocytes. In consequence, IC and AGF may induce two different activation phenotypes in EC that appear in a temporally and/or spatially coordinated manner in inflammatory tissues. Human guanylate binding protein-1 (hGBP-1) is a member of the large GTPase protein family. New results demonstrate that hGBP-1 is a specific marker of IC-activated EC that allows to differentiate the IC- and AGF-activated phenotype of EC at the single cell level, both in vitro and in vivo. In addition, hGBP-1 is the key mediator of the inhibitory effects of IC on EC proliferation and invasiveness. Both the expression pattern of hGBP-1 and its activity in EC supported the hypothesis that IC- and AGF-activation induce distinct adversely related phenotypes in EC. In future, hGBP-1 may be used as a marker to monitor the IC-induced phenotype of EC in inflammation and may also be exploited as a target to modulate EC activity in inflammatory diseases and tumor angiogenesis.

Gestational diabetes induces placental genes for chronic stress and inflammatory pathways

A physiological state of insulin resistance is required to preferentially direct maternal nutrients toward the feto-placental unit, allowing adequate growth of the fetus. When women develop gestational diabetes mellitus (GDM), insulin resistance is more severe and disrupts the intrauterine milieu, resulting in accelerated fetal development with increased risk of macrosomia. As a natural interface between mother and fetus, the placenta is the obligatory target of such environmental changes. However, the molecular basis for the imbalance that leads to fetal, neonatal, and adult metabolic compromises is not well understood. We report that GDM elicits major changes in the expression profile of placental genes with a prominent increase in markers and mediators of inflammation. Within the 435 transcripts reproducibly modified, genes for stress-activated and inflammatory responses represented the largest functional cluster (18.5% of regulated genes). Upregulation of interleukins, leptin, and tumor necrosis factor-alpha receptors and their downstream molecular adaptors indicated an activation of pathways recruiting stress-activated protein/c-Jun NH(2)-terminal kinases. Transcriptional activation of extracellular matrix components and angiogenic activators pointed to a major structural reorganization of the placenta. Thus, placental transcriptome emerges as a primary target of the altered environment of diabetic pregnancy. The genes identified provide the basis to elucidate links between inflammatory pathways and GDM-associated insulin resistance.

Ex vivo manipulation of umbilical cord blood-derived hematopoietic stem/progenitor cells with recombinant human stem cell factor can up-regulate levels of homing-essential molecules to increase their transmigratory potential

OBJECTIVE

The cause of delayed hematopoietic reconstitution after umbilical cord blood transplantation (UCBT) remains controversial. We hypothesized that hematopoietic stem/progenitor cells (HS/PCs) from UCB have some defects of the homing-related molecules responsible for their slow engraftment.

MATERIALS AND METHODS

A homing-related molecule repertoire expressed on HS/PCs from fresh and cryopreserved UCB, mobilized peripheral blood (mPB), and bone marrow (BM) were compared using sensitive, four-color fluorescence-activated cell sorting analysis. Purified CD34+ cells were subjected to ex vivo transmigration through double-coated transwell filter inserts, and an in vivo homing assay was performed in xenotransplanted NOD/SCID mice.

RESULTS

UCB-derived CD34(bright) cells expressed significantly lower levels of CD49e, CD49f, and CXCR-4 than their mPB and BM counterparts. CD34+ cells from UCB (and BM) exhibited significantly lower ex vivo transmigration than those from mPB, which were largely blocked by neutralizing antibodies to CD49e or CD49f. Recombinant human tumor necrosis factor-alpha treatment enhanced ex vivo transmigration of CD34+ cells from UCB and BM by inducing expression of the matrix metalloproteinases MMP-2/MMP-9. Short-term treatment of UCB-derived CD34+ cells with rHu-stem cell factor (rHuSCF) up-regulated levels of the homing-related molecules with their increased ex vivo transmigratory and in vivo homing potential.

CONCLUSION

Our results indicate that disadvantageous transmigratory behavior of HS/PCs from UCB, which might partly explain the delayed reconstitution after UCBT, can be reversed by ex vivo manipulation with rHuSCF.

A recombinant NH(2)-terminal heparin-binding domain of the adhesive glycoprotein, thrombospondin-1, promotes endothelial tube formation and cell survival: a possible role for syndecan-4 proteoglycan

Thrombospondin-1 (TSP-1) is a multifunctional protein known to modulate angiogenesis, endothelial cell adhesion and apoptosis. In this study, we have demonstrated that TSP18, a recombinant 18 kDa protein encompassing the N-terminal residues 1-174 of human TSP-1, accelerated the process of tube-like structures formation by human umbilical vein endothelial cells (HUVECs) when included in fibrin matrices at 0.55-2.2 microM concentrations, for times ranging from 24 to 72 h. This effect was specifically inhibited by V58A4, a Mab raised against TSP18. Whole TSP-1 showed a dual effect, weakly enhancing tube formation at 22 nM (10 microg/ml), but causing inhibition at 45 and 90 nM (20 and 40 microg/ml, respectively). In order to investigate the possible effects of TSP18 on cell adhesion and viability, we performed adhesion assays on different protein supports. HUVECs adhered more weakly on TSP-1-coated surfaces, remaining round-shaped, as compared to the well-spread phenotype displayed on fibronectin and gelatin. Cells adhering on TSP18-coated surfaces displayed a well spread phenotype, with this adhesion strongly inhibited by heparin. The binding of TSP18 to endothelial membrane extracts was blocked by a monoclonal IgG directed against the cell surface proteoglycan syndecan-4. The DNA fragmentation patterns and the nuclear morphology were comparable for HUVECs adhering on all proteins, including TSP18, showing minimal cell apoptosis. Our results indicate that the N-terminal region of TSP-1 constitutes a suitable adhesive support for HUVECs, protecting them from apoptosis, possibly mediated by syndecan-4 proteoglycan.

Up-regulation of thrombospondin-1 gene by epidermal growth factor and transforming growth factor beta in human cancer cells--transcriptional activation and messenger RNA stabilization

Thrombospondin-1 (TSP-1), a multifunctional matrix protein, affects tumor growth through modulation of angiogenesis and other stromal biological functions. In several of nine human cancer cell lines derived from liver, brain, pancreas, and bone, expression of TSP-1 was up-regulated in response to the two most representative growth factors, epidermal growth factor (EGF) and transforming growth factor beta1 (TGFbeta1). Expression of TSP-1 was markedly enhanced in hepatic HuH-7 cells by EGF but not by TGFbeta1. In contrast, expression of TSP-1 was markedly enhanced by TGFbeta1, but not by EGF, in osteosarcoma MG63 cells. EGF induced activation of TSP-1 promoter-driven luciferase activity in HuH-7 cells, and the elements between -267 and -71 on the 5' region of TSP-1 gene containing two GC boxes to which Sp1 bound, were found to be responsible for the promoter activation by EGF. However, EGF did not alter TSP-1 mRNA stability in hepatic cells. On the other hand, no such enhancement of the TSP-1 promoter activity by TGFbeta1 appeared in MG63 cells. Enhanced expression of TSP-1 by TGFbeta1 in MG63 cells was partially blocked by exogenous addition of SB203580, an inhibitor of p38 mitogen-activated protein kinase. TGFbeta was found to induce marked elongation of TSP-1 mRNA longevity in osteosarcoma cells when mRNA degradation was assayed in the presence of alpha-amanitin. The up-regulation of TSP-1 by EGF and TGFbeta might play a critical role in modulation of angiogenesis and formation of matrices in tumor stroma.

Association of thrombospondin-1 and cardiac allograft vasculopathy in human cardiac allografts

BACKGROUND

Despite the expression of angiogenic growth factors in transplanted hearts, neovessel formation appears scant. We therefore hypothesized that cardiac allografts contain endogenous inhibitors of angiogenesis. In particular, we tested the involvement in cardiac allografts of thrombospondin-1 (TSP-1), a matrix glycoprotein that inhibits angiogenesis and facilitates smooth muscle cell (SMC) proliferation.

METHODS AND RESULTS

Levels of TSP-1 mRNA in endomyocardial biopsy samples of human cardiac allografts substantially exceeded those in normal hearts. The ratio of TSP to GAPDH mRNA determined with quantitative RT-PCR was 6.54+/-1.6 in cardiac allografts versus 0.26+/-0.02 (P:=0.001) in normal hearts. Analysis in sequential biopsies revealed a strong association between persistent elevation of TSP-1 in allografts and the development of cardiac allograft vasculopathy (CAV). The CAV score was 2.4+/-0.8 in patients with persistent TSP-1 elevation compared with 0.2+/-0.2 in patients without elevation (P:=0.001). Immunohistochemistry demonstrated intense expression of TSP-1 in cardiac allografts, predominantly in cardiac myocytes and neointimal SMCs. In vitro experiments demonstrated that T cells expressed TSP-1, acidic fibroblast growth factor, and vascular endothelial cell growth factor on allogeneic stimulation. Cytokines known to be elevated in cardiac allografts (interleukin-1beta, interferon-gamma, and tumor necrosis factor-alpha) induced TSP-1 in SMCs but inhibited TSP-1 in endothelial cells.

CONCLUSIONS

Persistent elevation of TSP-1 in cardiac allografts correlates with the development of CAV. Allogeneic stimulation induces angiogenic growth factors and TSP-1 in T cells. Cytokines differentially regulate TSP-1 expression in SMCs versus endothelial cells. Increased levels of TSP-1 in human cardiac allografts may alter vascular responses to angiogenic growth factors by inhibiting angiogenesis and promoting SMC proliferation characteristic of CAV.

Thrombospondin-1 inhibits Kaposi's sarcoma (KS) cell and HIV-1 Tat-induced angiogenesis and is poorly expressed in KS lesions

Kaposi's sarcoma (KS), a neoplasm often associated with iatrogenic and acquired immunosuppression, is characterized by prominent angiogenesis. Angiogenic factors released by both KS and host cells, as well as HHV-8 and HIV viral products, have been implicated in the pathogenesis of this lesion. Angiogenesis is the result of imbalance among angiogenesis promoters and inhibitors, which disrupts homeostasis. The aim of this study was to investigate the expression and mechanism of KS control of thrombospondin-1 (TSP), a physiological inhibitor of angiogenesis. Immunohistochemical analysis of four KS lesions showed only spotty reactivity for TSP in the stroma and in less than 10 per cent of lesional blood vessels. In addition, the typical KS spindle cells were not stained. In agreement with these findings, decreased levels of TSP were measured with an ELISA assay in the supernatants of cultured KS cells, compared with endothelial cells. In vitro, TSP inhibited the endothelial cell proliferation and motility induced by KS cell supernatants. TSP also prevented endothelial cell motility induced by Tat, a product of HIV-1 endowed with angiogenic potential and implicated in the pathogenesis of AIDS-KS. In vivo, TSP inhibited the angiogenic activity exerted by Tat in the Matrigel sponge model. These results suggest that TSP down-regulation might be permissive for the development of KS-associated angiogenesis.

Regulation of cartilage oligomeric matrix protein synthesis in human synovial cells and articular chondrocytes

OBJECTIVE

Cartilage oligomeric matrix protein (COMP) is a component of the extracellular matrix of articular cartilage. Its increased presence in synovial fluid and serum has been associated with accelerated joint damage in patients with rheumatoid arthritis (RA) and osteoarthritis. To fully understand the reasons for fluctuations of COMP levels, we studied the biosynthesis of this molecule in cells derived from joint tissues.

METHODS

Synovial cells were derived from synovial tissues of patients with RA, and human articular chondrocytes were prepared from normal articular cartilage. Analysis by Northern blotting was used to evaluate steady-state levels of COMP messenger RNA (mRNA), while secretion of the protein into culture media was analyzed by Western blotting. Expression of COMP in synovial tissues was studied by reverse transcriptase-polymerase chain reaction analysis and by in situ hybridization.

RESULTS

COMP was synthesized and secreted by synovial cells as well as by articular chondrocytes in culture. The basal rate of synthesis was very low; however, COMP biosynthesis in both cell populations was induced very strongly by transforming growth factor beta1 (TGFbeta1). Interleukin-1beta counteracted COMP induction by TGF-beta1. COMP was not detected in culture media of skin or fetal lung fibroblasts, either in the absence or the presence of TGFbeta1. COMP mRNA was also present in fresh synovial tissue specimens obtained from patients with RA.

CONCLUSION

COMP is synthesized and secreted not only by articular chondrocytes, but also by synovial fibroblasts. The demonstration of COMP expression in surgical specimens of synovial tissues suggests that the inflamed synovium may provide an additional source for the elevated levels of COMP observed in arthritis. Thus, increased COMP levels in body fluids may be indicative of active synovitis as well as of accelerated joint erosion.

Cytokines and thyroid epithelial integrity: interleukin-1alpha induces dissociation of the junctional complex and paracellular leakage in filter-cultured human thyrocytes

Locally produced proinflammatory cytokines are likely to play a pathophysiological role in autoimmune thyroid disease. An important feature of the thyroid, not previously considered in cytokine actions, is the barrier created by the follicular epithelium, which secludes two lumenal autoantigens [thyroglobulin (Tg) and thyroperoxidase] from the extrafollicular space. We examined the influence of recombinant cytokines on the barrier function of human thyrocytes cultured as a tight and polarized monolayer in bicameral chambers. Whereas interleukin (IL)-6 (100 U/mL), interferon-gamma (100 U/mL), tumor necrosis factor-alpha (10 ng/mL), and transforming growth factor-beta1 (10 ng/mL) had no effects, exposure to IL-1alpha for 24-48 h reduced the transepithelial resistance from >1000 to <50 omega x cm2 and increased the paracellular flux of [3H]inulin and exogenous 125I-Tg. This response to IL-1alpha, which was dose dependent (1-1000 U/mL) and reversible, was accompanied by dramatic morphological changes of the epithelial junction complex, including aberrant localization of the tight junction protein zonula occludens-1. At the same time, IL-1alpha decreased the apical secretion of endogenous Tg and stimulated the basolateral release of a novel high-molecular-mass protein. We conclude that IL-1alpha reduces the thyroid epithelial barrier without signs of general cytotoxicity. The observation suggests a mechanism by which IL-1alpha may promote the exposure of hidden autoantigens to the immune system in thyroid autoimmunity.

Expression of interleukin-1beta in human breast carcinoma

BACKGROUND

Interleukin 1beta (IL-1beta) is a multifunctional cytokine that up-regulates the inflammatory response. It is not known whether IL-1beta plays a major role in human malignancy. To determine whether IL-1beta might be involved in breast carcinoma progression, the authors measured the IL-1beta content in tissue extracts from >200 invasive breast carcinomas and smaller numbers of ductal carcinoma in situ (DCIS) and benign lesions.

METHODS

IL-1beta content was measured by an enzyme-linked immunoadsorbent assay and analyzed to determine whether these values were correlated with the contents of scatter factor (SF) (an invasogenic and angiogenic cytokine), von Willebrand's factor (VWF) (a marker of endothelium), thrombospondin-1 (TSP1) (an antiadhesive and antiangiogenic glycoprotein), and tumor necrosis factor-alpha (TNF alpha) (another proinflammatory cytokine). Studies were also performed to determine whether IL-1beta content was correlated with other pathologic and immunochemical variables that have been utilized or proposed as prognostic indicators for breast carcinoma.

RESULTS

The most important findings of these studies were: 1) immunoreactive IL-1beta was detected in approximately 90% of invasive breast carcinomas; 2) IL-1beta levels were significantly higher in invasive carcinomas than in a group of DCIS and benign lesions; 3) high IL-1beta content in invasive carcinomas was significantly associated with higher contents of SF, VWF, and TSP1, but not TNF alpha; and 4) there was a trend toward higher IL-1beta content in invasive carcinomas with a group of other parameters that suggest a biologically more aggressive tumor (estrogen receptor negativity, high tumor grade, p53 positivity, and bcl-2 negativity); and the proportion of invasive tumors with these characteristics was significantly increased in a subgroup of tumors having very high IL-1beta content. The authors also found a correlation between high IL-1beta content and CD68 positivity, suggesting that macrophages may account for some of the IL-1beta present in human breast carcinoma tissue.

CONCLUSIONS

These findings suggest that significant titers of IL-1beta are present within the microenvironment of most breast carcinomas and that a high IL-1beta content is often associated with tumor invasiveness and with other pathologic features suggestive of an aggressive tumor biology.

Interleukin-1-alpha and de novo mammalian angiogenesis

In the literature, the role of interleukin-1 (IL-1) as an angiogen is controversial. The ability of IL-1-alpha to induce de novo angiogenesis in adult rats was studied using the mesenteric window angiogenesis assay (MWAA). Murine recombinant IL-1-alpha was injected intraperitoneally twice daily on Days 0 to 4 at 11.8 pM, 118 pM, and 1.18 nM and groups of animals were sacrificed on Days 7, 14, 21 and 28; controls received the vehicle. Angiogenesis was quantified in terms of microvascular spatial extension and density using technically independent microscopic techniques and image analysis. Compared with the vehicle control, the treatment with IL-1-alpha at doses of 118 pM and 1.18 nM induced statistically significant angiogenesis throughout the study period, whereas IL-1-alpha at 11.8 pM did not induce significant angiogenesis in statistical terms until Days 21 and 28. Compared with the previously reported angiogenic response to VEGF165, bFGF, IL-8, and TNF-alpha using the rat MWAA and the same standardized experimental protocol, the IL-1-alpha treatment displayed a higher degree of efficacy and potency than that of bFGF, IL-8, and TNF-alpha. Moreover, the duration of the significant response to IL-1-alpha exceeded that of bFGF, IL-8, and TNF-alpha. The present data indicate that IL-1-alpha at near-physiologic doses is a very effective angiogenic factor in the system used here. The response may well be multifactorially mediated, as is discussed, and the molecular mechanisms which are involved remain to be clarified.

Angiogenesis: new aspects relating to its initiation and control

Angiogenesis, the formation of new microvessels from parent microvessels, involves remodeling the basement membrane and interstitial extracellular matrix (ECM) using degrading proteases produced by the endothelial cells (ECs) and other adjacent cells, and the synthesis of ECM molecules by these cells. Degraded ECM releases previously bound heparin-binding cytokines (and growth factors) which are able to act as ligands to high-affinity receptors on various target cells, including ECs. The EC carries receptors for a number of cytokines which are produced by neighboring cells or released from the ECM and which can either induce or suppress the angiogenic phenotype of the EC. ECs are able to synthesize and secrete cytokines with auto- and paracrine effects. Angiogenesis, which virtually never occurs physiologically in adult tissues (except in the ovary, the endometrium and the placenta), is essential in wound healing and inflammation. Angiogenesis is, in fact, strictly controlled by a redundancy of pro- and anti-angiogenic paracrine peptide molecules, some of which have recently been described. The expression and synthesis of two distinct anti-angiogenic factors is, for example, controlled by the p53 tumor suppressor gene. In certain hypoxic conditions, chronic inflammatory diseases and syndromes, angiogenesis is of pathogenic and prognostic significance. Angiogenesis is, moreover, essential for the growth and metastatic spread of solid tumors. This indicates the potential for developing new therapeutic strategies not only for tumors but also in diseases such as rheumatoid arthritis, psoriasis, liver cirrhosis and diabetic retinopathy. Moreover, the therapeutic induction of angiogenesis in ischemic tissues using recombinant cytokines is also promising for clinical application. In fact, the first successful human gene therapy for stimulating angiogenesis has recently been reported.

TGF-beta and the endothelium during immune injury

During immune injury, activation of endothelial cells by inflammatory cytokines stimulates leukocyte adhesion to the endothelium, turns the endothelium from an anticoagulant surface to one that is frankly procoagulant, and results in the release of vasoactive mediators and growth factors. Cytokine activation of endothelial cells also results in increased endothelial cell TGF-beta 1 synthesis and enhanced activation of latent TGF-beta, the latter involving a shift of plasmin production from the apical to subendothelial surface. In cytokine-stimulated endothelial cells, TGF-beta hinders leukocyte adhesion and transmigration via inhibition of IL-8 and E-selectin expression. TGF-beta also profoundly diminishes cytokine-stimulated inducible nitric oxide synthase production and instead augments endothelial nitric oxide synthase expression. Thus, some of the TGF-beta actions on endothelium during immune activation can viewed as immunosuppressive. TGF-beta also influences mechanisms of vascular remodeling during the healing phase of immune injury. It stimulates PDGF-B synthesis by endothelial cells, causes bFGF release from subendothelial matrix, and promotes VEGF synthesis by non-endothelial cells. Together these mediators control angiogenesis, a critical component of the vascular repair phenomenon. Further, endothelial cell derived PDGF-B and bFGF influence the proliferation and migration of neighboring cells. Thus, endothelial cells and TGF-beta actions on the endothelium play important roles both during the initial phase of immune injury and during the later remodeling phase.

Immunohistochemical detection of thrombospondin in microglia in the developing rat brain

The development of microglia involves the expression of a phenotype displaying phagocytic behaviour termed brain macrophage or amoeboid microglial cell. We have previously shown that rat brain macrophages purified in vitro secrete thrombospondin, an extracellular matrix protein, which acts on cultured neuronal cells by promoting neurite growth. In the present study, the expression of thrombospondin was investigated in tissue sections of the developing rat forebrain in relation to the distribution of microglia. These cells were identified using anti-macrophage antibodies and the isolectin B4 from Bandeiraea simplicifolia. Immunocytochemical detection of thrombospondin clearly outlined a cell population displaying the morphologies and distribution of brain macrophages, from the 17th day of embryonic life up to the end of the second postnatal week. These cells were most numerous in cortical and subcortical regions of developing fibre tracts such as the corpus callosum or the internal capsule. The localization of thrombospondin in brain macrophages was confirmed by double immunostaining using ED1 monoclonal anti-macrophage antibodies. Ramified microglial cells were also labelled transiently by anti-thrombospondin antibodies during early postnatal life. These results provide in situ evidence supporting the notion that microglial cells could favour axonal growth by producing thrombospondin during development.