Downregulation of tenascin expression by glucocorticoids in bone marrow stromal cells and in fibroblasts

Biology of Tenascin C and its Role in Physiology and Pathology

Tenascin-C (TNC) is a multimodular extracellular matrix (ECM) protein hexameric with several molecular forms (180-250 kDa) produced by alternative splicing at the pre-mRNA level and protein modifications. The molecular phylogeny indicates that the amino acid sequence of TNC is a well-conserved protein among vertebrates. TNC has binding partners, including fibronectin, collagen, fibrillin-2, periostin, proteoglycans, and pathogens. Various transcription factors and intracellular regulators tightly regulate TNC expression. TNC plays an essential role in cell proliferation and migration. Unlike embryonic tissues, TNC protein is distributed over a few tissues in adults. However, higher TNC expression is observed in inflammation, wound healing, cancer, and other pathological conditions. It is widely expressed in a variety of human malignancies and is recognized as a pivotal factor in cancer progression and metastasis. Moreover, TNC increases both pro-and anti-inflammatory signaling pathways. It has been identified as an essential factor in tissue injuries such as damaged skeletal muscle, heart disease, and kidney fibrosis. This multimodular hexameric glycoprotein modulates both innate and adaptive immune responses regulating the expression of numerous cytokines. Moreover, TNC is an important regulatory molecule that affects the onset and progression of neuronal disorders through many signaling pathways. We provide a comprehensive overview of the structural and expression properties of TNC and its potential functions in physiological and pathological conditions.

The extracellular matrix of hematopoietic stem cell niches

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Comprehensive overview of different classes of ECM molecules in the HSC niche.

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Overview of current knowledge on role of biophysics of the HSC niche.

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Description of approaches to create artificial stem cell niches for several application.

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Importance of considering ECM in drug development and testing.

Hematopoietic stem cells (HSCs) are the life-long source of all types of blood cells. Their function is controlled by their direct microenvironment, the HSC niche in the bone marrow. Although the importance of the extracellular matrix (ECM) in the niche by orchestrating niche architecture and cellular function is widely acknowledged, it is still underexplored. In this review, we provide a comprehensive overview of the ECM in HSC niches. For this purpose, we first briefly outline HSC niche biology and then review the role of the different classes of ECM molecules in the niche one by one and how they are perceived by cells. Matrix remodeling and the emerging importance of biophysics in HSC niche function are discussed. Finally, the application of the current knowledge of ECM in the niche in form of artificial HSC niches for HSC expansion or targeted differentiation as well as drug testing is reviewed.

Tenascin-C Function in Glioma: Immunomodulation and Beyond

First identified in the 1980s, tenascin-C (TNC) is a multi-domain extracellular matrix glycoprotein abundantly expressed during the development of multicellular organisms. TNC level is undetectable in most adult tissues but rapidly and transiently induced by a handful of pro-inflammatory cytokines in a variety of pathological conditions including infection, inflammation, fibrosis, and wound healing. Persistent TNC expression is associated with chronic inflammation and many malignancies, including glioma. By interacting with its receptor integrin and a myriad of other binding partners, TNC elicits context- and cell type-dependent function to regulate cell adhesion, migration, proliferation, and angiogenesis. TNC operates as an endogenous activator of toll-like receptor 4 and promotes inflammatory response by inducing the expression of multiple pro-inflammatory factors in innate immune cells such as microglia and macrophages. In addition, TNC drives macrophage differentiation and polarization predominantly towards an M1-like phenotype. In contrast, TNC shows immunosuppressive function in T cells. In glioma, TNC is expressed by tumor cells and stromal cells; high expression of TNC is correlated with tumor progression and poor prognosis. Besides promoting glioma invasion and angiogenesis, TNC has been found to affect the morphology and function of tumor-associated microglia/macrophages in glioma. Clinically, TNC can serve as a biomarker for tumor progression; and TNC antibodies have been utilized as an adjuvant agent to deliver anti-tumor drugs to target glioma. A better mechanistic understanding of how TNC impacts innate and adaptive immunity during tumorigenesis and tumor progression will open new therapeutic avenues to treat brain tumors and other malignancies.

The Effect of Cyclosporine A on Dermal Fibroblast Cell - Transcriptomic Analysis of Inflammatory Response Pathway

BACKGROUND

The first immunosuppressive drug - cyclosporine A (CsA) has many unquestioned merits in maintaining organ transplants in patients, as well as, in the treatment of many inflammatory diseases, also associated with cutaneous manifestations. The main task of this drug is to suppress the inflammatory response at the sites of action, which is not well known.

OBJECTIVE

The objective of this study was to evaluate the influence of CsA in therapeutic concentration on the expression of genes associated with the inflammatory response pathway in normal human dermal fibroblasts (NHDF; CC-2511), and this study attempted to determine the mechanism of its action.

METHODS

The cytotoxicity MTT test was performed. The expression of the inflammatory response pathway genes was determined using HG-U133A_2.0 oligonucleotide microarrays. Statistical analysis was performed by GeneSpring 13.0 software using the PL-Grid platform.

RESULTS

Among the 5,300 mRNA, only 573 were changed significantly in response to CsA compared to the control fibroblasts (P≤0.05). CsA inhibited the expression of most genes associated with the inflammatory response in NHDFs. There were only 19 genes with a fold change (FC) lower than -2.0, among which EGR1, FOS, PBK, CDK1 and TOP2A had the lowest expression, as did CXCL2 which can directly impact inflammation. Furthermore, ZNF451 was strongly induced, and COL1A1, COL3A1, IL33, TNFRSFs were weakly up-regulated (FC lower than 2.0).

CONCLUSION

The CsA in therapeutic concentration influences the genes linked to the inflammatory response (in the transcriptional level) in human dermal fibroblasts. The findings suggest that the potential mechanism of CsA action in this concentration and on these genes can be associated with a profibrotic and proapoptotic, and genotoxic effects.

Loss of Tenascin-X expression during tumor progression: A new pan-cancer marker

Cancer is a systemic disease involving multiple components produced from both tumor cells themselves and surrounding stromal cells. The pro- or anti-tumoral role of the stroma is still under debate. Indeed, it has long been considered the main physical barrier to the diffusion of chemotherapy by its dense and fibrous nature and its poor vascularization. However, in murine models, the depletion of fibroblasts, the main ExtraCellular Matrix (ECM)-producing cells, led to more aggressive tumors even though they were more susceptible to anti-angiogenic and immuno-modulators. Tenascin-C (TNC) is a multifunctional matricellular glycoprotein (i.e. an ECM protein also able to induce signaling pathway) and is considered as a marker of tumor expansion and metastasis. However, the status of other tenascin (TN) family members and particularly Tenascin-X (TNX) has been far less studied during this pathological process and is still controversial. Herein, through (1) in silico analyses of the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases and (2) immunohistochemistry staining of Tissue MicroArrays (TMA), we performed a large and extensive study of TNX expression at both mRNA and protein levels (1) in the 6 cancers with the highest incidence and mortality in the world (i.e. lung, breast, colorectal, prostate, stomach and liver) and (2) in the cancers for which sparse data regarding TNX expression already exist in the literature. We thus demonstrated that, in most cancers, TNX expression is significantly downregulated during cancer progression and we also highlighted, when data were available, that high TNXB mRNA expression in cancer is correlated with a good survival prognosis.

Age-related differences in the bone marrow stem cell niche generate specialized microenvironments for the distinct regulation of normal hematopoietic and leukemia stem cells

The bone marrow (BM) microenvironment serves as a stem cell niche regulating the in vivo cell fate of normal hematopoietic stem cells (HSC) as well as leukemia stem cells (LSCs). Accumulating studies have indicated that the regeneration of normal HSCs and the process of leukemogenesis change with advancing age. However, the role of microenvironmental factors in these age-related effects are unclear. Here, we compared the stem cell niche in neonatal and adult BM to investigate potential differences in their microenvironmental regulation of both normal and leukemic stem cells. We found that the mesenchymal niche in neonatal BM, compared to adult BM, was characterized by a higher frequency of primitive subsets of mesenchymal stroma expressing both platelet-derived growth factor receptor and Sca-1, and higher expression levels of the niche cross-talk molecules, Jagged-1 and CXCL-12. Accordingly, normal HSCs transplanted into neonatal mice exhibited higher levels of regeneration in BM, with no difference in homing efficiency or splenic engraftment compared to adult BM. In contrast, in vivo self-renewal of LSCs was higher in adult BM than in neonatal BM, with increased frequencies of leukemia-initiating cells as well as higher lympho-myeloid differentiation potential towards biphenotypic leukemic cells. These differences in LSC self-renewal capacity between neonates and adults was abrogated by switching of recipients, confirming their microenvironmental origin. Our study provides insight into the differences in leukemic diseases observed in childhood and adults, and is important for interpretation of many transplantation studies involving neonatal animal models.

High serum levels of tenascin-C are associated with suicide attempts in depressed patients

The proteomic study reported that Tenascin-C might be a diagnostic biomarker for major depressive disorder, but clinical studies of this potential relationship are lacking. Here we examined the association between tenascin-C levels in serum and suicide attempts. Serum tenascin-C concentrations were compared among depressive patients who had not attempted suicide (n = 86), patients who had attempted it (n = 43), and healthy controls (n = 109). All participants were aged between 18 and 68 years. The association between concentration and suicide attempts was assessed by multivariate analysis after adjusting for sociodemographics, lifestyle and health indicators. Tenascin-C concentrations were higher in patients than in controls, and higher in patients who had attempted suicide than in patients who had not. Higher concentrations were associated with greater risk of attempting suicide. Among patients who had attempted suicide, tenascin-C concentrations were associated with severity of depression. Our results suggest that high tenascin-C levels in depressive patients correlate with suicide attempts and severity of depression. Tenascin-C may contribute to risk of suicide attempts in depressed patients.

Cyclosporin A inhibits adipogenic differentiation and regulates immunomodulatory functions of murine mesenchymal stem cells

Aplastic anemia (AA) is generally considered as an immune-mediated bone marrow failure syndrome. Several studies show that bone marrow mesenchymal stem cells (BM-MSCs), as key cellular components of the bone marrow microenvironment, are also involved in the pathogenic mechanism of AA. Cyclosporin A (CsA) is a classic immunosuppressive drug for AA, and it specifically inhibits mammalian T cells by preventing activation of transcription factors involved in cytokine gene expression. However, little is known about the effect of CsA on the BM-MSCs. In this study, murine BM-MSCs were stimulated in the presence of CsA. Further, we found that CsA could inhibit murine BM-MSC proliferation and promote BM-MSC apoptosis, what's more CsA could inhibit adipogenic differentiation. Our study also showed that CsA could inhibit interleukin-6 expression in BM-MSCs, while promoting programmed death-ligand 2 expression. In conclusion, our results proposed that CsA may exert an effect on regulating the bone marrow environment by influencing BM-MSCs, which have a beneficial effect on treating AA.

Increased Serum Levels of Fetal Tenascin-C Variants in Patients with Pulmonary Hypertension: Novel Biomarkers Reflecting Vascular Remodeling and Right Ventricular Dysfunction?

Pulmonary vascular remodeling is a pathophysiological feature that common to all classes of pulmonary hypertension (PH) and right ventricular dysfunction, which is the major prognosis-limiting factor. Vascular, as well as cardiac tissue remodeling are associated with a re-expression of fetal variants of cellular adhesion proteins, including tenascin-C (Tn-C). We analyzed circulating levels of the fetal Tn-C splicing variants B⁺ and C⁺ Tn-C in serum of PH patients to evaluate their potential as novel biomarkers reflecting vascular remodeling and right ventricular dysfunction. Serum concentrations of B⁺ and C⁺ Tn-C were determined in 80 PH patients and were compared to 40 healthy controls by enzyme-linked immunosorbent assay. Clinical, laboratory, echocardiographic, and functional data were correlated with Tn-C levels. Serum concentrations of both Tn-C variants were significantly elevated in patients with PH (p < 0.05). Significant correlations could be observed between Tn-C and echocardiographic parameters, including systolic pulmonary artery pressure (B⁺ Tn-C: r = 0.31, p < 0.001, C⁺ Tn-C: r = 0.26, p = 0.006) and right atrial area (B⁺ Tn-C: r = 0.46, p < 0.001, C⁺ Tn-C: r = 0.49, p < 0.001), and laboratory values like BNP (B⁺ Tn-C: r = 0.45, p < 0.001, C⁺ Tn-C: r = 0.42, p < 0.001). An inverse correlation was observed between Tn-C variants and 6-minute walk distance as a functional parameter (B⁺ Tn-C: r = -0.54, p < 0.001, C⁺ Tn-C: r = -0.43, p < 0.001). In a multivariate analysis, B⁺ Tn-C, but not C⁺ Tn-C, was found to be an independent predictor of pulmonary hypertension. Both fetal Tn-C variants may represent novel biomarkers that are capable of estimating both pulmonary vascular remodeling and right ventricular load. The potential beneficial impact of Tn-C variants for risk stratification in patients with PH needs further investigation.

Tenascin-C at a glance

Tenascin-C (TNC) is a hexameric, multimodular extracellular matrix protein with several molecular forms that are created through alternative splicing and protein modifications. It is highly conserved amongst vertebrates, and molecular phylogeny indicates that it evolved before fibronectin. Tenascin-C has many extracellular binding partners, including matrix components, soluble factors and pathogens; it also influences cell phenotype directly through interactions with cell surface receptors. Tenascin-C protein synthesis is tightly regulated, with widespread protein distribution in embryonic tissues, but restricted distribution of tenascin-C in adult tissues. Tenascin-C is also expressed de novo during wound healing or in pathological conditions, including chronic inflammation and cancer. First described as a modulator of cell adhesion, tenascin-C also directs a plethora of cell signaling and gene expression programs by shaping mechanical and biochemical cues within the cellular microenvironment. Exploitment of the pathological expression and function of tenascin-C is emerging as a promising strategy to develop new diagnostic, therapeutic and bioengineering tools. In this Cell Science at a Glance article and the accompanying poster we provide a succinct and comprehensive overview of the structural and functional features of tenascin-C and its potential roles in developing embryos and under pathological conditions.

Transcriptional regulation of tenascin genes

Extracellular matrix proteins of the tenascin family resemble each other in their domain structure, and also share functions in modulating cell adhesion and cellular responses to growth factors. Despite these common features, the 4 vertebrate tenascins exhibit vastly different expression patterns. Tenascin-R is specific to the central nervous system. Tenascin-C is an “oncofetal” protein controlled by many stimuli (growth factors, cytokines, mechanical stress), but with restricted occurrence in space and time. In contrast, tenascin-X is a constituitive component of connective tissues, and its level is barely affected by external factors. Finally, the expression of tenascin-W is similar to that of tenascin-C but even more limited. In accordance with their highly regulated expression, the promoters of the tenascin-C and -W genes contain TATA boxes, whereas those of the other 2 tenascins do not. This article summarizes what is currently known about the complex transcriptional regulation of the 4 tenascin genes in development and disease.

Carbon Monoxide Inhibits Tenascin-C Mediated Inflammation via IL-10 Expression in a Septic Mouse Model

Tenascin-C (TN-C), an extracellular matrix (ECM) glycoprotein, is specifically induced upon tissue injury and infection and during septic conditions. Carbon monoxide (CO) gas is known to exert various anti-inflammatory effects in various inflammatory diseases. However, the mechanisms underlying the effect of CO on TN-C-mediated inflammation are unknown. In the present study, we found that treatment with LPS significantly enhanced TN-C expression in macrophages. CO gas, or treatment with the CO-donor compound, CORM-2, dramatically reduced LPS-induced expression of TN-C and proinflammatory cytokines while significantly increased the expression of IL-10. Treatment with TN-C siRNA significantly suppressed the effects of LPS on proinflammatory cytokines production. TN-C siRNA did not affect the CORM-2-dependent increase of IL-10 expression. In cells transfected with IL-10 siRNA, CORM-2 had no effect on the LPS-induced expression of TN-C and its downstream cytokines. These data suggest that IL-10 mediates the inhibitory effect of CO on TN-C and the downstream production of proinflammatory cytokines. Additionally, administration of CORM-2 dramatically reduced LPS-induced TN-C and proinflammatory cytokines production while expression of IL-10 was significantly increased. In conclusion, CO regulated IL-10 expression and thus inhibited TN-C-mediated inflammation in vitro and in vivo.

In vitro study of novel gadolinium-loaded liposomes guided by GBI-10 aptamer for promising tumor targeting and tumor diagnosis by magnetic resonance imaging

Novel gadolinium-loaded liposomes guided by GBI-10 aptamer were developed and evaluated in vitro to enhance magnetic resonance imaging (MRI) diagnosis of tumor. Nontargeted gadolinium-loaded liposomes were achieved by incorporating amphipathic material, Gd (III) [N,N-bis-stearylamidomethyl-N'-amidomethyl] diethylenetriamine tetraacetic acid, into the liposome membrane using lipid film hydration method. GBI-10, as the targeting ligand, was then conjugated onto the liposome surface to get GBI-10-targeted gadolinium-loaded liposomes (GTLs). Both nontargeted gadolinium-loaded liposomes and GTLs displayed good dispersion stability, optimal size, and zeta potential for tumor targeting, as well as favorable imaging properties with enhanced relaxivity compared with a commercial MRI contrast agent (CA), gadopentetate dimeglumine. The use of GBI-10 aptamer in this liposomal system was intended to result in increased accumulation of gadolinium at the periphery of C6 glioma cells, where the targeting extracellular matrix protein tenascin-C is overexpressed. Increased cellular binding of GTLs to C6 cells was confirmed by confocal microscopy, flow cytometry, and MRI, demonstrating the promise of this novel delivery system as a carrier of MRI contrast agent for the diagnosis of tumor. These studies provide a new strategy furthering the development of nanomedicine for both diagnosis and therapy of tumor.

Matrix metalloproteinases in stem cell mobilization

Hematopoietic stem cells (HSCs) have the capability to migrate back and forth between their preferred microenvironment in bone marrow niches and the peripheral blood, but under steady-state conditions only a marginal number of stem cells can be found in the circulation. Different mobilizing agents, however, which create a highly proteolytic milieu in the bone marrow, can drastically increase the number of circulating HSCs. Among other proteases secreted and membrane-bound matrix metalloproteinases (MMPs) are known to be involved in the induced mobilization process and can digest niche-specific extracellular matrix components and cytokines responsible for stem cell retention to the niches. Iatrogenic stem cell mobilization and stem cell homing to their niches are clinically employed on a routine basis, although the exact mechanisms of both processes are still not fully understood. In this review we provide an overview on the various roles of MMPs in the induced release of HSCs from the bone marrow.

Biophysical regulation of hematopoietic stem cells

Blood is renewed throughout the entire life. The stem cells of the blood, called hematopoietic stem cells (HSCs), are responsible for maintaining a supply of all types of fresh blood cells. In contrast to other stem cells, the clinical application of these cells is well established and HSC transplantation is an established life-saving therapy for patients suffering from haematological disorders. Despite their efficient functionality throughout life in vivo, controlling HSC behaviour in vitro (including their proliferation and differentiation) is still a major task that has not been resolved with standard cell culture systems. Targeted HSC multiplication in vitro could be beneficial for many patients, because HSC supply is limited. The biology of these cells and their natural microenvironment - their niche - remain a matter of ongoing research. In recent years, evidence has come to light that HSCs are susceptible to physical stimuli. This makes the regulation of HSCs by engineering physical parameters a promising approach for the targeted manipulation of these cells for clinical applications. Nevertheless, the biophysical regulation of these cells is still poorly understood. This review sheds light on the role of biophysical parameters in HSC biology and outlines which knowledge on biophysical regulation identified in other cell types could be applied to HSCs.

The role of Tenascin C in the lymphoid progenitor cell niche

Hemopoietic stem cells (HSCs) are extrinsically controlled by the bone marrow (BM) microenvironment. Mice devoid of the extracellular matrix molecule Tenascin-C (TNC) were reported to develop normally. The current study explores the relationship between TNC and hemopoiesis, from HSCs within their niche to maturing progenitors in alternate niches. Although the absence of TNC did not alter the size of the BM stem cell pool, we report decreased thymic T cell progenitors with redistribution to other lymphoid organs, suggesting an anchoring role for TNC. TNC did not play an essential role in stem and progenitor cell homing to BM, but significantly altered lymphoid primed progenitor cell homing. These cells express the TNC receptor, integrin α9β1, with the same reduced homing evident in the absence of this integrin. The absence of TNC also resulted in an increased proportion and number of mature circulating T cells. In addition, the absence of TNC significantly impaired hemopoietic reconstitution after transplant and increased stem and progenitor cell mobilization. In summary, our analysis revealed unidentified roles for TNC in hemopoiesis: in lineage commitment of thymic T cell progenitors, peripheral T cell migration, and hemopoietic reconstitution.

Endogenous control of immunity against infection: tenascin-C regulates TLR4-mediated inflammation via microRNA-155

Endogenous molecules generated upon pathogen invasion or tissue damage serve as danger signals that activate host defense; however, their precise immunological role remains unclear. Tenascin-C is an extracellular matrix glycoprotein that is specifically induced upon injury and infection. Here, we show that its expression is required to generate an effective immune response to bacterial lipopolysaccharide (LPS) during experimental sepsis in vivo. Tenascin-C enables macrophage translation of proinflammatory cytokines upon LPS activation of toll-like receptor 4 (TLR4) and suppresses the synthesis of anti-inflammatory cytokines. It mediates posttranscriptional control of a specific subset of inflammatory mediators via induction of the microRNA miR-155. Thus, tenascin-C plays a key role in regulating the inflammatory axis during pathogenic activation of TLR signaling.

Matrikines and the lungs

The extracellular matrix is a complex network of fibrous and nonfibrous molecules that not only provide structure to the lung but also interact with and regulate the behaviour of the cells which it surrounds. Recently it has been recognised that components of the extracellular matrix proteins are released, often through the action of endogenous proteases, and these fragments are termed matrikines. Matrikines have biological activities, independent of their role within the extracellular matrix structure, which may play important roles in the lung in health and disease pathology. Integrins are the primary cell surface receptors, characterised to date, which are used by the matrikines to exert their effects on cells. However, evidence is emerging for the need for co-factors and other receptors for the matrikines to exert their effects on cells. The potential for matrikines, and peptides derived from these extracellular matrix protein fragments, as therapeutic agents has recently been recognised. The natural role of these matrikines (including inhibitors of angiogenesis and possibly inflammation) make them ideal targets to mimic as therapies. A number of these peptides have been taken forward into clinical trials. The focus of this review will be to summarise our current understanding of the role, and potential for highly relevant actions, of matrikines in lung health and disease.

Extracellular matrix molecules: potential targets in pharmacotherapy

The extracellular matrix (ECM) consists of numerous macromolecules classified traditionally into collagens, elastin, and microfibrillar proteins, proteoglycans including hyaluronan, and noncollagenous glycoproteins. In addition to being necessary structural components, ECM molecules exhibit important functional roles in the control of key cellular events such as adhesion, migration, proliferation, differentiation, and survival. Any structural inherited or acquired defect and/or metabolic disturbance in the ECM may cause cellular and tissue alterations that can lead to the development or progression of disease. Consequently, ECM molecules are important targets for pharmacotherapy. Specific agents that prevent the excess accumulation of ECM molecules in the vascular system, liver, kidney, skin, and lung; alternatively, agents that inhibit the degradation of the ECM in degenerative diseases such as osteoarthritis would be clinically beneficial. Unfortunately, until recently, the ECM in drug discovery has been largely ignored. However, several of today's drugs that act on various primary targets affect the ECM as a byproduct of the drugs' actions, and this activity may in part be beneficial to the drugs' disease-modifying properties. In the future, agents and compounds targeting directly the ECM will significantly advance the treatment of various human diseases, even those for which efficient therapies are not yet available.

Opposite effect of fluticasone and salmeterol on fibronectin and tenascin-C expression in primary human lung fibroblasts

BACKGROUND

Airway remodelling is a key feature of asthma and chronic obstructive pulmonary disease (COPD). The remodelling process involves the deposition of extracellular matrix (ECM) proteins within the airways. Current therapies for asthma and COPD consist of inhaled corticosteroids and long-acting beta(2)-agonists (LABA). However, their effect on airway remodelling is not well understood so far.

OBJECTIVE

In this study we investigated the effect of fluticasone and salmeterol, either alone or in combination, on fibronectin and tenascin-C protein, isoform, and mRNA levels in primary human lung fibroblasts.

METHODS

In our model, fibroblasts cultured in serum-free medium represented a non-inflammatory condition and stimulation with 5% fetal calf serum and/or TGF-beta(1) mimicked a pro-fibrotic environment with activation of tissue repair. Using these two different conditions, the effects of fluticasone and salmeterol on fibronectin and tenascin-C protein and mRNA levels were analysed by immunoblotting and semi-quantitative RT-PCR.

RESULTS

In both conditions, fluticasone increased fibronectin transcript and protein levels, whereas it decreased those of tenascin-C. Salmeterol neither affected fibronectin and tenascin-C synthesis significantly nor did it influence the effect of fluticasone when applied in combination. Furthermore, we found that treatment with fluticasone had an opposite effect on extra domain A and B containing fibronectin isoforms generated by alternative splicing compared with total fibronectin transcript levels, whereas tenascin-C isoforms were not differently modulated by fluticasone.

CONCLUSIONS

Our results indicate that standard therapies for inflammatory lung disorders influence ECM protein composition and relative expression levels. In contrast to corticosteroids, LABA did not significantly alter the expression of tenascin-C and fibronectin in cultures of primary human lung fibroblasts.

The regulation of tenascin expression by tissue microenvironments

Tenascins are a family of four extracellular matrix proteins: tenascin-C, X, R and W. The four members of the family have strikingly diverse patterns of expression during development and in the adult organism indicating independent mechanisms of regulation. In this review we illustrate that there are two types of tenascins, those that are significantly regulated by the tissue microenvironment (tenascin-C and tenascin-W), and those that have stabile, restricted expression patterns (tenascin-R and tenascin-X). We summarize what is known about the regulation of tenascin expression by transforming growth factor betas, fibroblast growth factors, platelet derived growth factors, as well as pro- and anti-inflammatory cytokines or hormones that either induce or inhibit expression of tenascins.

Novel genomic effects of glucocorticoids in epidermal keratinocytes: inhibition of apoptosis, interferon-gamma pathway, and wound healing along with promotion of terminal differentiation

Glucocorticoids (GCs) have a long history of use as therapeutic agents for numerous skin diseases. Surprisingly, their specific molecular effects are largely unknown. To characterize GC action in epidermis, we compared the transcriptional profiles of primary human keratinocytes untreated and treated with dexamethasone (DEX) for 1, 4, 24, 48, and 72 h using large scale microarray analyses. The majority of genes were found to be regulated only after 24 h and remained regulated throughout treatment. In addition to regulation of the expected pro-inflammatory genes, we found that GCs regulate cell fate, tissue remodeling, cell motility, differentiation, and metabolism. GCs suppress the expression of essentially all IFNgamma-regulated genes, including IFNgamma receptor and STAT-1, an effect that was previously unknown. GCs also block STAT-1 activation and nuclear translocation. Unexpectedly, GCs induce the expression of anti-apoptotic genes and repress pro-apoptotic ones, preventing UV-induced keratinocyte apoptosis. Consequently, treatment with GCs blocked UV-induced apoptosis of keratinocytes. GCs have profound effect on wound healing by inhibiting cell motility and the expression of the proangiogenic factor, vascular endothelial growth factor. They play an important role in tissue remodeling and scar formation by suppressing the expression of TGFbeta1 and -2 and MMP1, -2, -9, and -10 and inducing TIMP-2. Finally, GCs promote terminal epidermal differentiation while simultaneously inhibiting early stage differentiation. These results provide new insights into the beneficial and adverse effects of GCs in the epidermis, defining the participating genes and mechanisms that coordinate the cellular responses important for GC-based therapies.

Glucocorticoid therapy-induced skin atrophy

Glucocorticoids (GCs) are highly effective for the topical treatment of inflammatory skin diseases. Their long-term use, however, is often accompanied by severe and partially irreversible adverse effects, with atrophy being the most prominent limitation. Progress in the understanding of GC-mediated molecular action as well as some advances in technologies to determine the atrophogenic potential of compounds has been made recently. It is likely that the detailed mechanisms of GC-induced skin atrophy will be discovered and in vitro models for the reliable prediction of atrophy will be established in the foreseeable future. This knowledge will not only facilitate safety profiling of established drugs but will also foster further drug discovery by improving compound characterization processes. New insights into GC modes of action will guide optimization strategies aiming at novel GC receptor ligands with improved effect/side effect profile.

Identification of tenascin-C as a key molecule determining stromal cell-dependent erythropoiesis

OBJECTIVE

We previously established 33 bone marrow stromal cell lines from SV40 T-antigen transgenic mice. Of these, 27 clones supported erythroid colony formation, while 6 did not. The objective of this study is to identify the molecules that determine these erythroid colony-forming activities.

MATERIALS AND METHODS

We compared gene expression profiling by DNA microarray between cell lines that support erythropoiesis (E(+); TBR9, 184, 31-2) and cell lines that do not (E(-); TBR17, 33, 511). Among the differentially expressed genes, we selected candidate genes with results of quantitative reverse transcriptase polymerase chain reaction, and examined the effect of small interfering RNA (siRNA) and the addition of exogenous proteins on the erythroid colony formation.

RESULTS

Out of 7226 genes examined, 138 and 282 genes were upregulated and downregulated in E(+) by threefold or more, respectively. We have selected one of the upregulated genes, tenascin-C (TN-C), as a candidate. Expressions of TN-C in E(+) were all higher than the three E-cell lines, with a mean of 3.6-fold. The number of erythroid colonies in the presence of TN-C siRNA was significantly lower than that of control siRNA in TBR9 (20.7 +/- 6.3 vs 4.7 +/- 4.8 colonies; p = 0.01) and in TBR184 (13.3 +/- 5.3 vs 0.3 +/- 0.5; p = 0.02). Moreover, addition of exogenous TN-C enhanced the number of erythroid colonies in TBR184 (13.3 +/- 3.5 vs 20.0 +/- 2.0; p = 0.04) and in TBR31-2 (7.5 +/- 3.1 vs 13.5 +/- 2.6; p = 0.03).

CONCLUSION

These results suggest that TN-C is responsible for determining the stromal cell-dependent erythropoiesis.

Interleukin-4 and dexamethasone counterregulate extracellular matrix remodelling and phagocytosis in type-2 macrophages

Alternatively activated macrophages (Mphi2) are induced by Th2 cytokines and by glucocorticoids (GC), and can be distinguished from classically activated effector macrophages (Mphi1) on the basis of their anti-inflammatory properties. In addition, Mphi2 are involved in Th2/Th1 skewing, enhance antigen uptake and processing and support tissue remodelling and healing. In order to elucidate the heterogeneity of Mphi2 population systematically, we analysed a number of genes involved in extracellular matrix (ECM) remodelling, inflammation and phagocytosis in Mphi2 populations generated with interleukin-4 (IL-4) or GC. Using real-time polymerase chain reaction, we demonstrated that the ECM component, tenascin-C, is stimulated by IL-4, whereas it is suppressed by dexamethasone. The ECM remodelling enzymes--MMP-1 and MMP-12--and tissue transglutaminase (TG) showed a similar regulation pattern. FXIIIa, another putative Mphi2-associated TG, was synergistically regulated by IL-4 and GC. Enzyme-linked immunosorbent assay analysis revealed that the production of Mphi2-associated chemokines, AMAC-1, MCP-4 or TARC, was induced by IL-4 and was modulated by GC. Phagocytosis of opsonized and non-opsonized particles was stimulated by GC, whereas IL-4 had only a modulatory effect, what may be partially explained by the expression pattern of hMARCO, a scavenger receptor for non-opsonized particles, that was strongly and selectively induced by GC. In conclusion, stimulation of Mphi with IL-4 and GC regulate antagonistically the expression of ECM remodelling-related molecules and phagocytosis of opsonized and non-opsonized particles.

Induction of hepatic hematopoiesis with tenascin-C expression during the second trimester of development

OBJECTIVE

To determine the role of tenascin-C in fetal hepatic hematopoietic proliferation and differentiation in different stages of development.

STUDY DESIGN

We examined and compared the immunohistochemical expression of tenascin-C in the hepatic stromal portal fields in the first, second, and third trimester of gestation respectively, in relation to the appearance of CD34 progenitor hematopoietic, stromal progenitor and vascular endothelial positive cells.

RESULTS

Our results demonstrated a quantitative difference in the second trimester of gestation concerning the expression of tenascin-C in the connective tissue stroma of the hepatic portal fields over the equivalent expression of the protein in the first (P<0.0001, t-test) and third trimester (P<0.0001, t-test). Similar changes in the above period were found concerning the expression of CD34 over the first (P<0.0001, t-test) and third trimesters (P<0.0001, t-test), suggesting a direct involvement of tenascin-C in the sustaining of hematopoietic activity.

CONCLUSIONS

Our data provide evidence that an ECM glycoprotein component, tenascin-C, plays a relevant role in hematopoiesis through interaction between stromal cells and hematopoietic progenitor cells.

Binding of mouse nidogen-2 to basement membrane components and cells and its expression in embryonic and adult tissues suggest complementary functions of the two nidogens

Nidogen-1 binds several basement membrane components by well-defined, domain-specific interactions. Organ culture and gene targeting approaches suggest that a high-affinity nidogen-binding site of the laminin gamma1 chain (gamma1III4) is important for kidney development and for nerve guidance. Other proteins may also bind gamma1III4, although human nidogen-2 binds poorly to the mouse laminin gamma1 chain. We therefore characterized recombinant mouse nidogen-2 and its binding to basement membrane proteins and cells. Mouse nidogen-1 and -2 interacted at comparable levels with collagen IV, perlecan, and fibulin-2 and, most notably, also with laminin-1 fragments P1 and gamma1III3-5, which both contain the gamma1III4 module. In embryos, nidogen-2 mRNA was produced by mesenchyme at sites of epithelial-mesenchymal interactions, but the protein was deposited on epithelial basement membranes, as previously shown for nidogen-1. Hence, binding of both nidogens to the epithelial laminin gamma1 chain is dependent on epithelial-mesenchymal interactions. Epidermal growth factor stimulated expression of both nidogens in embryonic submandibular glands. Both nidogens were found in all studied embryonic and adult basement membranes. Nidogen-2 was more adhesive than nidogen-1 for some cell lines and was mainly mediated by alpha3beta1 and alpha6beta1 integrins as shown by antibody inhibition. These findings revealed extensive coregulation of nidogen-1 and -2 expression and much more complementary functions of the two nidogens than previously recognized.

Laminin gamma2 chain as a stromal cell marker of the human bone marrow microenvironment

Laminins are large heterotrimeric molecules consisting of alpha, beta and gamma chains. At present, five alpha chains, three beta chains and three gamma chains have been characterized. Laminin-5 (alpha3beta3gamma2) is the only isoform known to date which contains a gamma2 chain. In human bone marrow, non-haematopoietic stromal cells expressed the laminin gamma2 chain, whereas bone marrow mononuclear cells did not. Co-localization of the gamma2 chain was detected with the laminin alpha4 and alpha5 chains, and co-immunoprecipitation studies revealed a new isoform consisting of alpha5, beta2 and gamma2 chains. The laminin gamma2 chain was also co-localized with alpha-sm-actin in bone marrow, but it was not expressed in endothelial cells or megakaryocytes, indicating that the gamma2 chain is exclusively expressed in vivo in bone marrow stromal cells. The laminin gamma2 chain containing isoform LN-5 was shown to be an adhesive substrate for a small subpopulation of bone marrow mononuclear cells and also for peripheral blood platelets. Taken together, these results indicate that (I) laminin isoforms containing the gamma2 chain can act as adhesive substrates for human haematopoietic cells, and (II) the laminin gamma2 chain can be used as a specific marker molecule for human bone-marrow-derived stromal cells.

Glucocorticoids down-regulate the extracellular matrix proteins fibronectin, fibulin-1 and fibulin-2 in bone marrow stroma

Glucocorticoids regulate hematopoietic cell interactions with the bone marrow microenvironment, but the molecules involved in the regulation are still largely unknown. We have studied the effect of glucocorticoids on mRNA expression and protein synthesis of the major extracellular matrix adhesion protein fibronectin and three other extracellular proteins, fibulin-1, fibulin-2 and nidogen-1, in mouse bone marrow cultures and in a hematopoiesis supporting the stromal MC3T3-G2/PA6 cell line. Glucocorticoids suppressed mRNA expression and protein synthesis of fibronectin, fibulin-1 and fibulin-2, but not nidogen-1, in adherent cells of bone marrow cultures, as shown by Northern blot analysis and immunoprecipitation. mRNA levels of all four proteins were down-regulated by dexamethasone in MC3T3-G2/PA6 cells, indicating a direct glucocorticoid effect on cells synthesizing extracellular matrix proteins. Dexamethasone down-regulated fibronectin mRNA rapidly, within 2 h of treatment, in the stromal cells. This effect did not require mRNA or protein synthesis, as shown by Northern blot analysis after treatment by actinomycin D and cycloheximide. Interferon-alpha, which also has been reported to modulate haematopoietic cell-matrix interactions, did not affect mRNA expression of the proteins in MC3T3-G2/PA6 cells. Our results indicate that glucocorticoids down-regulate expression of several mesenchymal-type extracellular matrix molecules in bone marrow, but with a variable effect on different proteins. Thus one mechanism by which glucocorticoids regulate haematopoiesis may be by altering the relative proportions of extracellular matrix proteins.

Rapid and reciprocal regulation of tenascin-C and tenascin-Y expression by loading of skeletal muscle

Tenascin-C and tenascin-Y are two structurally related extracellular matrix glycoproteins that in many tissues show a complementary expression pattern. Tenascin-C and the fibril-associated minor collagen XII are expressed in tissues bearing high tensile stress and are located in normal skeletal muscle, predominantly at the myotendinous junction that links muscle fibers to tendon. In contrast, tenascin-Y is strongly expressed in the endomysium surrounding single myofibers, and in the perimysial sheath around fiber bundles. We previously showed that tenascin-C and collagen XII expression in primary fibroblasts is regulated by changes in tensile stress. Here we have tested the hypothesis that the expression of tenascin-C, tenascin-Y and collagen XII in skeletal muscle connective tissue is differentially modulated by mechanical stress in vivo. Chicken anterior latissimus dorsi muscle (ALD) was mechanically stressed by applying a load to the left wing. Within 36 hours of loading, expression of tenascin-C protein was ectopically induced in the endomysium along the surface of single muscle fibers throughout the ALD, whereas tenascin-Y protein expression was barely affected. Expression of tenascin-C protein stayed elevated after 7 days of loading whereas tenascin-Y protein was reduced. Northern blot analysis revealed that tenascin-C mRNA was induced in ALD within 4 hours of loading while tenascin-Y mRNA was reduced within the same period. In situ hybridization indicated that tenascin-C mRNA induction after 4 hours of loading was uniform throughout the ALD muscle in endomysial fibroblasts. In contrast, the level of tenascin-Y mRNA expression in endomysium appeared reduced within 4 hours of loading. Tenascin-C mRNA and protein induction after 4–10 hours of loading did not correlate with signs of macrophage infiltration. Tenascin-C protein decreased again with removal of the load and nearly disappeared after 5 days. Furthermore, loading was also found to induce expression of collagen XII mRNA and protein, but to a markedly lower level, with slower kinetics and only partial reversibility. The results suggest that mechanical loading directly and reciprocally controls the expression of extracellular matrix proteins of the tenascin family in skeletal muscle.

Adiponectin, a new member of the family of soluble defense collagens, negatively regulates the growth of myelomonocytic progenitors and the functions of macrophages

We investigated the functions of adiponectin, an adipocyte-specific secretory protein and a new member of the family of soluble defense collagens, in hematopoiesis and immune responses. Adiponectin suppressed colony formation from colony-forming units (CFU)—granulocyte-macrophage, CFU-macrophage, and CFU-granulocyte, whereas it had no effect on that of burst-forming units—erythroid or mixed erythroid-myeloid CFU. In addition, adiponectin inhibited proliferation of 4 of 9 myeloid cell lines but did not suppress proliferation of erythroid or lymphoid cell lines except for one cell line. These results suggest that adiponectin predominantly inhibits proliferation of myelomonocytic lineage cells. At least one mechanism of the growth inhibition is induction of apoptosis because treatment of acute myelomonocytic leukemia lines with adiponectin induced the appearance of subdiploid peaks and oligonucleosomal DNA fragmentation. Aside from inhibiting growth of myelomonocytic progenitors, adiponectin suppressed mature macrophage functions. Treatment of cultured macrophages with adiponectin significantly inhibited their phagocytic activity and their lipopolysaccharide-induced production of tumor necrosis factor α. Suppression of phagocytosis by adiponectin is mediated by one of the complement C1q receptors, C1qRp, because this function was completely abrogated by the addition of an anti-C1qRp monoclonal antibody. These observations suggest that adiponectin is an important negative regulator in hematopoiesis and immune systems and raise the possibility that it may be involved in ending inflammatory responses through its inhibitory functions.

Adiponectin, a new member of the family of soluble defense collagens, negatively regulates the growth of myelomonocytic progenitors and the functions of macrophages

We investigated the functions of adiponectin, an adipocyte-specific secretory protein and a new member of the family of soluble defense collagens, in hematopoiesis and immune responses. Adiponectin suppressed colony formation from colony-forming units (CFU)—granulocyte-macrophage, CFU-macrophage, and CFU-granulocyte, whereas it had no effect on that of burst-forming units—erythroid or mixed erythroid-myeloid CFU. In addition, adiponectin inhibited proliferation of 4 of 9 myeloid cell lines but did not suppress proliferation of erythroid or lymphoid cell lines except for one cell line. These results suggest that adiponectin predominantly inhibits proliferation of myelomonocytic lineage cells. At least one mechanism of the growth inhibition is induction of apoptosis because treatment of acute myelomonocytic leukemia lines with adiponectin induced the appearance of subdiploid peaks and oligonucleosomal DNA fragmentation. Aside from inhibiting growth of myelomonocytic progenitors, adiponectin suppressed mature macrophage functions. Treatment of cultured macrophages with adiponectin significantly inhibited their phagocytic activity and their lipopolysaccharide-induced production of tumor necrosis factor α. Suppression of phagocytosis by adiponectin is mediated by one of the complement C1q receptors, C1qRp, because this function was completely abrogated by the addition of an anti-C1qRp monoclonal antibody. These observations suggest that adiponectin is an important negative regulator in hematopoiesis and immune systems and raise the possibility that it may be involved in ending inflammatory responses through its inhibitory functions.

Deflazacort increases laminin expression and myogenic repair, and induces early persistent functional gain in mdx mouse muscular dystrophy

Deflazacort slows the progress of Duchenne muscular dystrophy (DMD) with fewer side effects than prednisone. In mdx mice, deflazacort treatment augments repair and growth of new muscle fibers. We tested the hypothesis that deflazacort improves muscle function and promotes repair by increasing myogenic cell proliferation and fiber differentiation. mdx mice (3.5 weeks old) were treated with deflazacort (1.2 mg/kg) or vehicle for 4 weeks. Forelimb grip strength was measured. After 4 weeks, the right tibialis anterior muscle (TA) was crush injured to induce synchronous regeneration. DNA was labeled using different markers 24 and 2 h before collecting tissues 4 days after injury. The expression of creatine kinase (CK) isoforms, laminin-2 (merosin) mRNA and protein, and proliferation by myogenic cells were measured and satellite cells were identified by immunolocalization of c-met receptor. Peak grip strength increased 15% within 10 days of treatment, and was maintained up to 6 weeks after the end of treatment in a second experiment. Expression of CK MM in the regenerating TA rose from 46% to 55% of total CK activity after deflazacort treatment. Satellite cells were more numerous and appeared earlier on new fibers, in concert with a threefold increase in proliferation by myogenin+ (but not MyoD+) myoblasts. alpha2-Laminin mRNA expression and protein increased 1.3-5.5-fold relative to MM CK in regenerating and dystrophic TA, respectively. These studies support the hypothesis that deflazacort promotes functional gains, myogenic differentiation, myoblast fusion, and laminin expression in regenerating dystrophic muscle. The potential to augment precursor specification, strength, and possible membrane stability may be useful in directing long-term benefits for DMD patients and short-term amplification of precursors prior to myoblast transfer.

The tenascin family of ECM glycoproteins: structure, function, and regulation during embryonic development and tissue remodeling

The determination of animal form depends on the coordination of events that lead to the morphological patterning of cells. This epigenetic view of development suggests that embryonic structures arise as a consequence of environmental influences acting on the properties of cells, rather than an unfolding of a completely genetically specified and preexisting invisible pattern. Specialized cells of developing multicellular organisms are surrounded by a complex extracellular matrix (ECM), comprised largely of different collagens, proteoglycans, and glycoproteins. This ECM is a substrate for tissue morphogenesis, lends support and flexibility to mature tissues, and acts as an epigenetic informational entity in the sense that it transduces and integrates intracellular signals via distinct cell surface receptors. Consequently, ECM-receptor interactions have a profound influence on major cellular programs including growth, differentiation, migration, and survival. In contrast to many other ECM proteins, the tenascin (TN) family of glycoproteins (TN-C, TN-R, TN-W, TN-X, and TN-Y) display highly restricted and dynamic patterns of expression in the embryo, particularly during neural development, skeletogenesis, and vasculogenesis. These molecules are reexpressed in the adult during normal processes such as wound healing, nerve regeneration, and tissue involution, and in pathological states including vascular disease, tumorigenesis, and metastasis. In concert with a multitude of associated ECM proteins and cell surface receptors that include members of the integrin family, TN proteins impart contrary cellular functions, depending on their mode of presentation (i.e., soluble or substrate-bound) and the cell types and differentiation states of the target tissues. Expression of tenascins is regulated by a variety of growth factors, cytokines, vasoactive peptides, ECM proteins, and biomechanical factors. The signals generated by these factors converge on particular combinations of cis-regulatory elements within the recently identified TN gene promoters via specific transcriptional activators or repressors. Additional complexity in regulating TN gene expression is achieved through alternative splicing, resulting in variants of TN polypeptides that exhibit different combinations of functional protein domains. In this review, we discuss some of the recent advances in TN biology that provide insights into the complex way in which the ECM is regulated and how it functions to regulate tissue morphogenesis and gene expression.

Association of extracellular matrix proteins fibulin-1 and fibulin-2 with fibronectin in bone marrow stroma

Extracellular matrix (ECM) molecules, together with growth factors and stromal cells, regulate haematopoietic cell development in bone marrow (BM). We report here expression of ECM proteins fibulin-1 and fibulin-2 in mouse BM. In other tissues, fibulin-1 and fibulin-2 associate with fibronectin and other ECM proteins. Fibulin-2 has also been found to adhere to cells via beta3 integrins. We studied the association of fibulins with fibronectin in BM stroma. By confocal microscopy, fibulin-1 and fibulin-2 immunostainings were co-localized with fibronectin in the adherent layer of long-term BM cultures. In cell adhesion assays using recombinant proteins, mouse fibulin-2 adhered to human erythroid-megakaryocytic leukaemia cell line HEL. This adhesion was mediated by beta3 integrins. However, HEL cells did not adhere to human fibulin-2. We therefore studied a possible species-specific cell-adhesive activity of mouse fibulin-2 by using mouse megakaryocytes, obtained by culture of BM cells in the presence of thrombopoietin. These megakaryocytes did not adhere to mouse fibulin-2. Our findings suggested that the functional role of fibulin-1 and fibulin-2 in BM stroma is related to binding to the major cell adhesion protein fibronectin, whereas adhesion of mouse fibulin-2 to human cells containing the integrin beta3 chain is not related to an apparent physiological function of the protein.

Glucocorticoid-regulated gene expression during cutaneous wound repair

Glucocorticoids exert a deleterious effect on the wound healing process, which has been suggested to result from the anti-inflammatory action of these steroids. In addition, recent studies have demonstrated that glucocorticoids regulate the expression of various genes at the wound site which are likely to encode key players in the wound repair process. Using a murine full-thickness excisional wound healing model, we analyzed the effect of dexamethasone on the expression of various cytokines, growth factors, enzymes, and extracellular matrix molecules in normal and wounded skin. We demonstrate that the proinflammatory cytokines interleukin-1 alpha and -beta, tumor necrosis factor alpha, keratinocyte growth factor, transforming growth factors beta 1, beta 2, and beta 3 and their receptors, platelet-derived growth factors and their receptors, tenascin-C, stromelysin-2, macrophage metalloelastase, and enzymes involved in the generation of nitric oxide are targets of glucocorticoid action in wounded skin. These results indicate that anti-inflammatory steroids inhibit wound repair at least in part by influencing the expression of these key regulatory molecules.

Intracerebral transplantation of bone marrow with BDNF after MCAo in rat

We tested the hypothesis that a composite graft of fresh bone marrow (BM) along with brain-derived neurotrophic factor (BDNF), transplanted into the ischemic boundary zone (IBZ) of rat brain, facilitates BM cells to survive and differentiate, and improves functional recovery after middle cerebral artery occlusion (MCAo). The fresh BM was harvested from adult rats injected with bromodeoxyuridine (BrdU) as a tracer. Rats (n=37) were subjected to 2h of MCAo, received grafts at 24h and were sacrificed at 7days after MCAo. Test groups consisted of: (1) control - MCAo alone (n=9); (2) injection of phosphate buffered saline (n=4); (3) transplantation of BM (n=8); (4) injection of BDNF (n=7); and (5) transplantation of BM with BDNF (n=9) into the IBZ. Immunohistochemistry was used to identify cells derived from the BM stem cells. Behavioral tests (rotarod motor test; adhesive-removal somatosensory test) were performed before and 7days after MCAo. The data indicate that intracerebral grafting of a combination of BM with BDNF enhances differentiation of BM cells and significantly improves motor recovery of rotarod (P<0.05) and adhesive-removal (P<0.05) tests. We anticipate that BM along with neurotrophic factors may provide a powerful autoplastic therapy for human neurological injury and degenerative disorders.

Tenascin is expressed in the mesenchyme of the embryonic lung and down-regulated by dexamethasone in early organogenesis

Tenascin (TN) is a hexameric extracellular matrix glycoprotein that is temporally and spatially restricted during lung development. This study examines the expression and regulation of TN in early lung organogenesis. Two TN isoforms were detected in total RNA isolated from embryonic day 14 rat lung tissues by reverse transcriptase polymerase chain reaction. The localization of TN in embryonic day 14 rat lung tissues was investigated by using in situ hybridization performed with an antisense RNA probe. TN mRNA was expressed exclusively by the mesenchyme but not by the epithelium of embryonic rat lungs. The intense expression of TN was observed in the mesenchyme that immediately surrounds the growing epithelial cells of the developing bronchi. The effect of the synthetic glucocorticoid hormone dexamethasone on the regulation of TN expression was examined by in vitro lung explant culture. Two TN polypeptides, the larger (M(r) 230 kDa, TN230) polypeptide and the smaller (M(r) 180 kDa, TN180) isoform, were detected in embryonic day 21 rat lungs by immunoblot analysis with anti-TN antibody. Dexamethasone inhibited both TN230 and TN180 biosynthesis. The study demonstrates the expression of TN at the early stage of lung organogenesis and presents evidence of hormonal regulation of TN in lung development, suggesting a potential role of TN in the communication between the epithelial and mesenchymal cells during lung branching morphogenesis.

Tenascin-C modulates tumor stroma and monocyte/macrophage recruitment but not tumor growth or metastasis in a mouse strain with spontaneous mammary cancer

The local growth of tumors and their ability to metastasize are crucially dependent on their interactions with the surrounding extracellular matrix. Tenascin-C (TNC) is an extracellular matrix protein which is highly expressed during development, tissue repair and cancer. Despite the high levels of TNC in the stroma of primary and metastatic tumors, the function of TNC is not known. In the present study we have crossed TNC-null mice with a mouse strain where both female and male mice spontaneously develop mammary tumors followed by metastatic disease in the lungs. We report that the absence of TNC had no effect on the temporal occurrence of mammary tumors and their metastatic dissemination in lungs. Furthermore, the number and size of tumors, the number and size of metastatic foci in the lungs, the proliferation rate and apoptosis of tumor cells and tumor angiogenesis were not altered in the absence of TNC. Histological examination revealed that the tumor organisation, however, was modulated by TNC. In the presence of TNC both primary as well as metastatic tumors were organised in large tumor cell nests surrounded by thick layers of extracellular matrix proteins. In the absence of TNC these tumor cell nests were smaller but still separated from each other by extracellular matrix proteins. In addition, the TNC-null stromal compartment contained significantly more monocytes/macrophages than tumor stroma from TNC wild-type mice. Using in vitro coculture experiments we show that TNC-null tumor cells were still able to activate the TNC gene in fibroblasts which express low basal levels of TNC. Altogether these data indicate that TNC has a very limited role during the spontaneous development and growth of mamary tumors and their metastasis to the lungs.

Characterization of Bone Marrow Laminins and Identification of 5-Containing Laminins as Adhesive Proteins for Multipotent Hematopoietic FDCP-Mix Cells

Laminins are extracellular matrix glycoproteins that influence the phenotype and functions of many types of cells. Laminins are heterotrimers composed of , β, and γ polypeptides. So far five , three β, and two γ polypeptide chains, and 11 variants of laminins have been proposed. Laminins interact in vitro with mature blood cells and malignant hematopoietic cells. Most studies have been performed with laminin-1 (1β1γ1), and its expression in bone marrow is unclear. Employing an antiserum reacting with most laminin isoforms, we found laminins widely expressed in mouse bone marrow. However, no laminin 1 chain but rather laminin 2, 4, and 5 polypeptides were found in bone marrow. Our data suggest presence of laminin-2 (2β1γ1), laminin-8 (4β1γ1), and laminin-10 (5β1γ1) in bone marrow. Northern blot analysis showed expression of laminin 1, 2, 4, and 5 chains in long-term bone marrow cultures, indicating upregulation of laminin 1 chain expression in vitro. Laminins containing 5 chain, in contrast to laminin-1, were strongly adhesive for multipotent hematopoietic FDCP-mix cells. Integrin 6 and β1 chains mediated this adhesion, as shown by antibody perturbation experiments. Our findings indicate that laminins other than laminin-1 are functional in adhesive interactions in bone marrow.

Characterization of Bone Marrow Laminins and Identification of 5-Containing Laminins as Adhesive Proteins for Multipotent Hematopoietic FDCP-Mix Cells

Laminins are extracellular matrix glycoproteins that influence the phenotype and functions of many types of cells. Laminins are heterotrimers composed of , β, and γ polypeptides. So far five , three β, and two γ polypeptide chains, and 11 variants of laminins have been proposed. Laminins interact in vitro with mature blood cells and malignant hematopoietic cells. Most studies have been performed with laminin-1 (1β1γ1), and its expression in bone marrow is unclear. Employing an antiserum reacting with most laminin isoforms, we found laminins widely expressed in mouse bone marrow. However, no laminin 1 chain but rather laminin 2, 4, and 5 polypeptides were found in bone marrow. Our data suggest presence of laminin-2 (2β1γ1), laminin-8 (4β1γ1), and laminin-10 (5β1γ1) in bone marrow. Northern blot analysis showed expression of laminin 1, 2, 4, and 5 chains in long-term bone marrow cultures, indicating upregulation of laminin 1 chain expression in vitro. Laminins containing 5 chain, in contrast to laminin-1, were strongly adhesive for multipotent hematopoietic FDCP-mix cells. Integrin 6 and β1 chains mediated this adhesion, as shown by antibody perturbation experiments. Our findings indicate that laminins other than laminin-1 are functional in adhesive interactions in bone marrow.

Inhibition of tenascin-C expression in mammary epithelial cells by thyroid hormone

Multiple data suggest a relationship between thyroid hormone (triiodothyronine (T3)) and carcinogenesis. Studies on breast cancer have been inconclusive, suggesting contradictory effects of thyroid status and diseases. Recently, we reported that expression of the extracellular matrix glycoprotein tenascin-C is modulated by T3 during rat brain development. Because tenascin-C has been reported to have growth-, motility-, and angiogenic-promoting activities and to become upregulated during tumorigenesis in breast carcinoma and stromal cells, we analyzed the effects of T3 on tenascin-C expression in mammary epithelial cells. In this study, we showed that tenascin-C RNA expression was inhibited by T3 in normal un-transformed EpH4 mouse mammary epithelial cells expressing appropriate receptors. T3's action appeared to be due to a decreased half-life of the tenascin-C mRNA, with a maximum effect (85% at 100 nM) 48 h after addition. T3 also downregulated tenascin-C in the human mammary tumor cell line SKBR-3, which expresses endogenous thyroid receptors. Immunoprecipitation experiments confirmed that tenascin-C protein content was also decreased by T3 in EpH4 cells (70% reduction at 100 nM). Dexamethasone had a similar inhibitory effect (70% at 100 nM), whereas estradiol, the antiestrogen ICI 164,384, progesterone, and all-trans retinoic acid did not alter tenascin-C expression. Our data demonstrate an inhibitory action of T3 on tenascin-C expression in mammary epithelial cells that may play a role in the physiological regulation of this gene and in neoplastic processes.

Surface topography and serum concentration affect the appearance of tenascin in human gingival fibroblasts in vitro

Tenascin is an extracellular matrix glycoprotein which affects cell behavior such as cell migration. This study was undertaken to investigate the time of appearance of tenascin (TN) in human gingival fibroblasts (HGF) and how it was affected by the surface topography of the titanium substratum or by serum concentration in the medium. HGF were cultured for 4 to 24 h and then processed for confocal immunofluorescence microscopy. Very few cells stained positive for TN 4 h after plating, but the number of TN-positive HGF gradually increased between 8 and 18 h after plating. The increase in the rate of the proportion of TN-positive cells on the grooved surface lagged behind that of HGF cultured on the smooth surface. The number of TN-positive cells in medium + 15% serum was significantly greater than that of cells in 5% serum or serum-free medium. The number of TN-positive cells was greater on the smooth titanium surface than on the grooved titanium surface in both 15% serum and 5% serum-containing medium. These findings suggest that TN production by fibroblasts in vitro can be modulated by factors in serum and by the surface topography of the substratum.

Mitogenic and adhesive effects of tenascin-C on human hematopoietic cells are mediated by various functional domains

In the adult organism, the extracellular matrix molecule tenascin-C is prominently expressed in the bone marrow. Bone marrow mononuclear cells can adhere to plastic-immobilized tenascin-C, and in the present study we have used bacterial expression proteins to map the domains of tenascin-C responsible for binding of hematopoietic cells. A strong binding site was found to be located within the fibrinogen-like domain, and this binding could be inhibited by heparin, suggesting interactions with membrane-bound heparan sulfate proteoglycans. A second strong binding site was identified within the fibronectin type III-like repeats 6-8, and was also inhibitable by heparin. Adhesion to both attachment sites could not be blocked by various anti-integrin antibodies. A third hematopoietic cell binding site is located in the fibronectin type III-like repeats 1-5, which harbor an RGD sequence in the third fibronectin type III-like repeat. Binding to this domain, however, seems to be RGD-independent, since RGD-containing peptides could not inhibit cell binding; the addition of heparin also did not block adhesion to this domain. Since contradictory results had been reported on a proliferative effect of soluble tenascin-C, we also analyzed its activity on hematopoietic cells. The heterogeneous bone marrow mononuclear cells show a striking proliferative response in the presence of tenascin-C which is concentration-dependent. This result indicates a strong mitogenic activity of tenascin-C on primary hematopoietic cells. Using recombinant fragments of human tenascin-C, we identified several mitogenic domains within the tenascin-C molecule. These adhesive and mitogenic effects of tenascin-C suggest a direct functional association with proliferation and differentiation of hematopoietic cells within the bone marrow microenvironment.

Tenascin is increased in airway basement membrane of asthmatics and decreased by an inhaled steroid

Tenascin and fibronectin are extracellular matrix glycoproteins expressed during morphogenesis and tissue repair. In the present study bronchial biopsies were studied by the morphometric method of immunocytochemistry to reveal the distribution of different tenascin and fibronectin isoforms as well as the presence of inflammatory cells in the airway mucosa of patients with chronic asthma (n = 32) and those with seasonal birch-pollen-sensitive asthma out of season (n = 17), both in comparison with healthy control subjects (n = 12). The results showed an increase in tenascin immunoreactivity in the bronchial subepithelial reticular basement membrane layer in patients with chronic asthma (p < 0.0001) and in those with seasonal asthma (p < 0.01) compared with control subjects. The tenascin immunoreactivity, appearing as an intense wide subepithelial band in asthma, was seen only occasionally in the basement membrane of control specimens. Instead, a diffuse immunoreaction against both total fibronectin and locally produced extradomain A fibronectin was similarly visible in the airway mucosa of both patients and control subjects. Despite the significant increase in the airway mucosa of eosinophils and lymphocytes in patients with chronic asthma (p < 0.0001 and p < 0.0001, respectively) and of eosinophils in patients with seasonal asthma (p < 0.001), there was no correlation between the number of these cell types and level of tenascin expression. In patients with birch-pollen-sensitive asthma during the birch-pollen season, inhaled corticosteroid treatment, budesonide 400 micrograms twice daily, decreased tenascin immunoreactivity, in comparison with effects of placebo (p = 0.01). Our results suggest that the higher amount of tenascin reflects disease activity in asthma and may be an indicator of a remodeling process rather than of injury itself.

Neuronal differentiation in SH-SY5Y human neuroblastoma cells induces synthesis and secretion of tenascin and upregulation of alpha(v) integrin receptors

Human SH-SY5Y neuroblastoma cells were induced to neuronal differentiation by using 12-0-tetradecanoylphorbol-13-acetate (TPA) and retinoic acid (RA). Both treatments rapidly induced long neurites and increased the content of neurofilaments as shown by immunocytochemistry and immunoblotting. Immunoprecipitation and immunoblotting of the culture medium with monoclonal antibodies demonstrated a rapid onset of synthesis and secretion of Mr 280,000 tenascin (Tn) polypeptide with TPA and both Mr 280,000 and 190,000 Tn polypeptides with RA and an increased secretion of extradomain A cellular fibronectin (EDA-Fn) upon both treatments. Upon RA treatment both Tn polypeptides were also found in extracellular matrix preparations of the differentiated cells. A diffuse extracellular Tn immunoreactivity and a distinct cytoplasmic reaction were seen in differentiated cells especially after exposure to monensin to inhibit cellular secretion. Instead, immunoprecipitation experiments suggested that laminin was synthesized by the cells but was not upregulated upon differentiation. Experiments with purified Tn, used to coat the culture substratum, demonstrated that the undifferentiated cells were unable to adhere or spread on Tn but rapidly acquired the spreading capacity upon differentiation with the inducing agents. In immunofluorescence and immunoblotting the undifferentiated cells presented only a faint heterogenous reaction for beta1 integrin (Int) subunit, whereas cells exposed to RA presented a strong reaction for the Int alpha1 and beta1 subunits, hence suggestive of Int alpha1beta1, and for Int alpha(v) subunit. Cells exposed to TPA showed an enhanced immunoreaction for Int alpha2 and beta1 subunits, suggestive of Int alpha2beta1, and for Int alpha(v) subunit. Immunoreactivity for Int alpha(v) located to distinct punctate plaques in the differentiated cells after both inducing agents. The results suggest that Tn is produced by cultured neuronally differentiating cells, and it is accompanied by the acquitance of an adhesion receptor for Tn.