Inherited Proteoglycan Biosynthesis Defects-Current Laboratory Tools and Bikunin as a Promising Blood Biomarker

Proteoglycans consist of proteins linked to sulfated glycosaminoglycan chains. They constitute a family of macromolecules mainly involved in the architecture of organs and tissues as major components of extracellular matrices. Some proteoglycans also act as signaling molecules involved in inflammatory response as well as cell proliferation, adhesion, and differentiation. Inborn errors of proteoglycan metabolism are a group of orphan diseases with severe and irreversible skeletal abnormalities associated with multiorgan impairments. Identifying the gene variants that cause these pathologies proves to be difficult because of unspecific clinical symptoms, hardly accessible functional laboratory tests, and a lack of convenient blood biomarkers. In this review, we summarize the molecular pathways of proteoglycan biosynthesis, the associated inherited syndromes, and the related biochemical screening techniques, and we focus especially on a circulating proteoglycan called bikunin and on its potential as a new biomarker of these diseases.

Exploration of human xylosyltransferase for chemoenzymatic synthesis of proteoglycan linkage region

Proteoglycans (PGs) play important roles in many biological processes including tumor progression, cell adhesion, and regulation of growth factor activities. With glycosaminoglycan chains attached to the core proteins in nature, PGs are highly challenging synthetic targets due to the difficulties in integrating the sulfated glycans with the peptide backbone. To expedite the synthesis, herein, the utility of human xylosyltransferase I (XT-I), the enzyme responsible for initiating PG synthesis, has been explored. XT-I was found to be capable of efficiently installing the xylose unit onto a variety of peptide structures on mg scales. Furthermore, an unnatural sugar, i.e., 6-azidoglucose can be transferred by XT-I introducing a reactive handle onto the glycopeptide for selective functionalization. XT-I can be coupled with β-4-galactosyl transferase-7 for one pot synthesis of glycopeptides bearing galactose-xylose disaccharide, paving the way toward efficient chemoenzymatic synthesis of PG glycopeptides and glycoproteins.

Endocan, a novel inflammatory marker, is upregulated in human chondrocytes stimulated with IL-1 beta

Endocan is a circulating proteoglycan, involved in immunity, inflammation, and endothelial function. It has been recently suggested as a biomarker of inflammation, increased angiogenesis, and cancer. In vitro studies have shown that endocan expression could be upregulated by inflammatory cytokines and proangiogenic molecules. High endocan levels were also shown in arthritic joint tissues and particularly in sites characterized by severe inflammation. This study was performed to evaluate endocan expression in chondrocytes stimulated with IL-ß. mRNA and related protein production were measured for endocan, TNF-α, and IL-6. NF-kB activity was also evaluated. IL-1ß treatment induced a significant upregulation of both endocan and the inflammatory parameters as well as NF-kB activity. The treatment of chondrocytes with the specific NF-kB inhibitor before IL-1ß stimulation was able to reduce endocan and the inflammatory markers over-expression. The results of our study indicated that endocan is also expressed in human chondrocytes; furthermore, consistent with previous results in other cell types and tissues, IL-1ß-induced inflammatory response involves the expression of endocan through NF-kB activation. In this context, endocan seems to be an important inflammatory marker associated with the activation of NF-kB pathway.

Activation of the Interleukin-33/ST2 Pathway Exerts Deleterious Effects in Myxomatous Mitral Valve Disease

Mitral valve disease (MVD) is a frequent cause of heart failure and death worldwide, but its etiopathogenesis is not fully understood. Interleukin (IL)-33 regulates inflammation and thrombosis in the vascular endothelium and may play a role in the atherosclerotic process, but its role in mitral valve has not been investigated. We aim to explore IL-33 as a possible inductor of myxomatous degeneration in human mitral valves. We enrolled 103 patients suffering from severe mitral regurgitation due to myxomatous degeneration undergoing mitral valve replacement. Immunohistochemistry of the resected leaflets showed IL-33 and ST2 expression in both valve interstitial cells (VICs) and valve endothelial cells (VECs). Positive correlations were found between the levels of IL-33 and molecules implicated in the development of myxomatous MVD, such as proteoglycans, extracellular matrix remodeling enzymes (matrix metalloproteinases and their tissue inhibitors), inflammatory and fibrotic markers. Stimulation of single cell cultures of VICs and VECs with recombinant human IL-33 induced the expression of activated VIC markers, endothelial–mesenchymal transition of VECs, proteoglycan synthesis, inflammatory molecules and extracellular matrix turnover. Our findings suggest that the IL-33/ST2 system may be involved in the development of myxomatous MVD by enhancing extracellular matrix remodeling.

Lysophosphatidic acid receptor 5 transactivation of TGFBR1 stimulates the mRNA expression of proteoglycan synthesizing genes XYLT1 and CHST3

Lysophosphatidic acid (LPA) via transactivation dependent signalling pathways contributes to a plethora of physiological and pathophysiological responses. In the vasculature, hyperelongation of glycosaminoglycan (GAG) chains on proteoglycans leads to lipid retention in the intima resulting in the early pathogenesis of atherosclerosis. Therefore, we investigated and defined the contribution of transactivation dependent signalling in LPA mediated GAG chain hyperelongation in human vascular smooth muscle cells (VSMCs). LPA acting via the LPA receptor 5 (LPAR5) transactivates the TGFBR1 to stimulate the mRNA expression of GAG initiation and elongation genes xylosyltransferase-1 (XYLT1) and chondroitin 6-sulfotransferase-1 (CHST3), respectively. We found that LPA stimulates ROS and Akt signalling in VSMCs, however they are not associated in LPAR5 transactivation of the TGFBR1. We observed that LPA via ROCK dependent pathways transactivates the TGFBR1 to stimulate genes associated with GAG chain elongation. We demonstrate that GPCR transactivation of the TGFBR1 occurs via a universal biochemical mechanism and the identified effectors represent potential therapeutic targets to inhibit pathophysiological effects of GPCR transactivation of the TGFBR1.

Selective Elimination of NG2-Expressing Hair Follicle Stem Cells Exacerbates the Sensitization Phase of Contact Dermatitis in a Transgenic Rat Model

The hair cycle consists of three different phases: anagen (growth), catagen (regression), and telogen (resting). During the anagen phase, hair follicle stem cells (HFSCs) in the bulge and the secondary hair germ proliferate and generate the outer and inner root sheath cells and the hair shafts. We previously identified NG2-immunoreactive (NG2+) cells as HFSCs in both regions of the hair follicles. Recently, the interaction between the hair cycle and the cutaneous immune system has been re-examined under physiological and pathological conditions. However, the roles of NG2+ HFSCs in the skin’s immune system remain completely elucidated. In the present study, we investigated whether the elimination of NG2+ HFSCs affects the induction of allergic contact dermatitis, using a herpes simplex virus thymidine kinase (HSVtk)/ganciclovir (GCV) suicide gene system. When the GCV solution was applied to the skin of NG2-HSVtk transgenic (Tg) rats during the depilation-induced anagen phase, NG2+ HFSCs in the Tg rat skin induced apoptotic cell death. Under exposure of a hapten, the selective ablation of NG2+ HFSCs during the anagen phase aggravated the sensitization phase of allergic contact dermatitis. These findings suggest that NG2+ HFSCs and their progeny have immunosuppressive abilities during the anagen phase.

Enhanced Coproduction of Cell-Bound Zeaxanthin and Secreted Exopolysaccharides by Sphingobium sp. via Metabolic Engineering and Optimized Fermentation

Zeaxanthin is a value-added carotenoid with wide applications. This study aims to manipulate a generally recognized as safe and carotenoid-producing bacterium, Sphingobium sp., for enhanced production of zeaxanthin and exopolysaccharides. First, whole-genome sequencing and analysis of pathway genes were applied to define the carotenoid pathway in Sphingobium sp. Second, a Sphingobium transformation system was established to engineer metabolite flux into zeaxanthin. By a combination of chemical mutagenesis and removal of bottlenecks of carotenoid biosynthesis via overexpression of three rate-limiting enzymes, the genetically modified Sphingobium DIZ strain produced 21.26 mg/g dry cell weight of zeaxanthin, which was about 4-fold higher than the wild type. Upon optimization of culture conditions, the DIZ strain produced 479.5 mg/L of zeaxanthin with the productivity of 4.99 mg/L/h and 21.9 g/L of exopolysaccharides using a fed-batch fermentation strategy. This study represents the first genetic manipulation of Sphingobium sp., a biotechnologically important bacterium, for high-yield production of value-added metabolites.

Defining the role of NG2-expressing cells in experimental models of multiple sclerosis. A biofunctional analysis of the neurovascular unit in wild type and NG2 null mice

During experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis associated with blood-brain barrier (BBB) disruption, oligodendrocyte precursor cells (OPCs) overexpress proteoglycan nerve/glial antigen 2 (NG2), proliferate, and make contacts with the microvessel wall. To explore whether OPCs may actually be recruited within the neurovascular unit (NVU), de facto intervening in its cellular and molecular composition, we quantified by immunoconfocal morphometry the presence of OPCs in contact with brain microvessels, during postnatal cerebral cortex vascularization at postnatal day 6, in wild-type (WT) and NG2 knock-out (NG2KO) mice, and in the cortex of adult naïve and EAE-affected WT and NG2KO mice. As observed in WT mice during postnatal development, a higher number of juxtavascular and perivascular OPCs was revealed in adult WT mice during EAE compared to adult naïve WT mice. In EAE-affected mice, OPCs were mostly associated with microvessels that showed altered claudin-5 and occludin tight junction (TJ) staining patterns and barrier leakage. In contrast, EAE-affected NG2KO mice, which did not show any significant increase in vessel-associated OPCs, seemed to retain better preserved TJs and BBB integrity. As expected, absence of NG2, in both OPCs and pericytes, led to a reduced content of vessel basal lamina molecules, laminin, collagen VI, and collagen IV. In addition, analysis of the major ligand/receptor systems known to promote OPC proliferation and migration indicated that vascular endothelial growth factor A (VEGF-A), platelet-derived growth factor-AA (PDGF-AA), and the transforming growth factor-β (TGF-β) were the molecules most likely involved in proliferation and recruitment of vascular OPCs during EAE. These results were confirmed by real time-PCR that showed Fgf2, Pdgfa and Tgfb expression on isolated cerebral cortex microvessels and by dual RNAscope-immunohistochemistry/in situ hybridization (IHC/ISH), which detected Vegfa and Vegfr2 transcripts on cerebral cortex sections. Overall, this study suggests that vascular OPCs, in virtue of their developmental arrangement and response to neuroinflammation and growth factors, could be integrated among the classical NVU cell components. Moreover, the synchronized activation of vascular OPCs and pericytes during both BBB development and dysfunction, points to NG2 as a key regulator of vascular interactions.

Hydrodynamic Stimulation and Long Term Cultivation of Nucleus Pulposus Cells: A New Bioreactor System to Induce Extracellular Matrix Synthesis by Nucleus Pulposus Cells Dependent on Intermittent Hydrostatic Pressure

A novel bioreactor system was constructed to induce extracellular matrix (ECM) synthesis by intervertebral disc (ID) cells due to intermittent hydrostatic pressure. The developed system is completely sterilizable and reusable. It is viable for cultivation, immobilization, and stimulation of various other cell types and tissues especially for cartilage. The custom made lid allows long-run cultivation through semi-continuous operation. Manual interferences and therefore the risk of contamination are reduced. Sampling, medium changing and addition of supplements are easily performed from the connected conditioning vessel, which could be placed in an incubator.

For the present investigations nucleus pulposus cells from pigs were taken and immobilized in agarose to obtain three-dimensional cell matrix constructs which were subjected to intermittent hydrostatic pressure. Afterwards the construct was biochemically examined. The proven constituents of ECM were found to be released in dependence of the magnitude and profile of the applied pressure.

Pentosan polysulfate binds to STRO-1+ mesenchymal progenitor cells, is internalized, and modifies gene expression: a novel approach of pre-programing stem cells for therapeutic application requiring their chondrogenesis

BACKGROUND

The pharmaceutical agent pentosan polysulfate (PPS) is known to induce proliferation and chondrogenesis of mesenchymal progenitor cells (MPCs) in vitro and in vivo. However, the mechanism(s) of action of PPS in mediating these effects remains unresolved. In the present report we address this issue by investigating the binding and uptake of PPS by MPCs and monitoring gene expression and proteoglycan biosynthesis before and after the cells had been exposed to limited concentrations of PPS and then re-established in culture in the absence of the drug (MPC priming).

METHODS

Immuno-selected STRO-1+ mesenchymal progenitor stem cells (MPCs) were prepared from human bone marrow aspirates and established in culture. The kinetics of uptake, shedding, and internalization of PPS by MPCs was determined by monitoring the concentration-dependent loss of PPS media concentrations using an enzyme-linked immunosorbent assay (ELISA) and the uptake of fluorescein isothiocyanate (FITC)-labelled PPS by MPCs. The proliferation of MPCs, following pre-incubation and removal of PPS (priming), was assessed using the Wst-8 assay method, and proteoglycan synthesis was determined by the incorporation of 35SO4 into their sulphated glycosaminoglycans. The changes in expression of MPC-related cell surface antigens of non-primed and PPS-primed MPCs from three donors was determined using flow cytometry. RNA sequencing of RNA isolated from non-primed and PPS-primed MPCs from the same donors was undertaken to identify the genes altered by the PPS priming protocol.

RESULTS

The kinetic studies indicated that, in culture, PPS rapidly binds to MPC surface receptors, followed by internalisation and localization within the nucleus of the cells. Following PPS-priming of MPCs and a further 48 h of culture, both cell proliferation and proteoglycan synthesis were enhanced. Reduced expression of MPC-related cell surface antigen expression was promoted by the PPS priming, and RNA sequencing analysis revealed changes in the expression of 42 genes.

CONCLUSION

This study has shown that priming of MPCs with low concentrations of PPS enhanced chondrogenesis and MPC proliferation by modifying their characteristic basal gene and protein expression. These findings offer a novel approach to re-programming mesenchymal stem cells for clinical indications which require the repair or regeneration of cartilaginous tissues such as in osteoarthritis and degenerative disc disease.

The relationship between proteoglycan inhibition via xylosyltransferase II silencing and the implantation of salivary pleomorphic adenoma

OBJECTIVE

To study the relationship between proteoglycan inhibition and the implantation of salivary pleomorphic adenoma (SPA).

METHODS

SPA fresh tissue was primitively cultured and identified. The Ad-shRNA-XT-II adenovirus vector was constructed and transfected into SPA cells to silence the XT-II gene. The expression of the XT-II gene and protein was detected using real-time PCR and Western blotting, respectively. The proteoglycan content of the cells was determined 48 h after transfection. The invasion and migration of SPA cells were observed using Matrigel invasion and wound-healing assays. Fibroblasts from the tumour capsule of the same patient were obtained, cultured and seeded onto an acellular dermal matrix (ADM) scaffold. Tumour cells were seeded onto the scaffold with the fibroblasts and then transferred to BALB/C-nu nude mice and allowed to grow in vivo for 3 months.

RESULTS

The SPA cells cultures were positive for human calponin, S-100 protein, α-SMA and CK. XT-II gene and protein expression was decreased by 42.72% and 34%, respectively. The proteoglycan content was downregulated by 41.15%. XT-II gene silencing decreased the invasion and migration abilities of SPA cells. The assessment of SPA growth in nude mice indicated an absence of tumour growth in the SPA-XT-II group (in which the XT-II gene was silenced), whereas SPA growth was observed in the other two groups (in which the XT-II gene was not silenced), and the tumour tissue was positive for the human S-100 protein, α-SMA and CK8&18.

CONCLUSION

Proteoglycan inhibition induced via XT-II gene silencing inhibited the implantation of SPA.

Altered Liver Proteoglycan/Glycosaminoglycan Structure as a Manifestation of Extracellular Matrix Remodeling upon BCG-induced Granulomatosis in Mice

Experimental BCG-induced granulomatosis in mice was used to study changes in the dynamics of individual liver proteoglycan components reflecting phasic extracellular matrix remodeling, determined by the host-parasite interaction and associated with granuloma development. In the early BCG-granulomatosis period, the increase in individual proteoglycan components promotes granuloma formation, providing conditions for mycobacteria adhesion to host cells, migration of phagocytic cells from circulation, and cell-cell interaction leading to granuloma development and fibrosis. Later, reduced reserve capacity of the extracellular matrix, development of interstitial fibrosis and granuloma fibrosis can lead to trophic shortage for cells within the granulomas, migration of macrophages out of them, and development of spontaneous necrosis and apoptosis typical of tuberculosis.

A Role for Proteoglycans in Mineralized Tissue-Titanium Adhesion

Biomechanical properties of the bone-titanium interface have rarely been studied, due to the technical limitations involved; whether biological bonding mechanisms exist has not been determined. We hypothesized that a selected set of proteoglycan/glycosaminoglycan complexes plays a role in establishing the adhesion between bone and titanium, and utilized the rat bone-marrow-derived osteoblastic culture model to gain an insight into the hypothesis. Gene expression of selected proteoglycan core proteins was up-regulated in the osteoblasts cultured on titanium compared with those on polystyrene. Various sulfated glycosaminoglycans were immunochemically localized at mineralized tissue-titanium interfaces. The administration of various glycosaminoglycan-degrading enzymes into the cultures resulted in a 25–45% reduction of the tissue-titanium interfacial strength, measured by a nanoscratch test; while the hardness and elastic modulus of the mineralized tissue, evaluated by nano-indentation, were not altered. In conclusion, glycosaminoglycan degradation resulted in a decreased interfacial strength between cultured mineralized tissue and titanium, but did not alter the intrinsic strength of the mineralized tissue, suggesting a role for proteoglycan/glycosaminoglycan complexes in the establishment of tissue-titanium adhesion.

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The anabolic effects require brief exposures to higher than average PTH concentrations. The catabolic effects result from pathological conditions in which parathyroid glands secrete too much hormone continuously at a sustained level. The aim of the present study was observance of intermittent (I-PTH) and continuous (C-PTH) PTH 1-34 administration influence on bovine chondrogenic progenitor cells (CPC) differentiation. Alcian blue was used to determine proteoglycan accumulation in CPC monolayer cultures. Thus in plates containing CPCs in C-PTH media chondrogenic differentiation was indicated by intensive proteoglycan accumulation in extracellular matrix. CPCs monolayer cultured in osteogenic media were subjected to Alizarin Red staining for matrix mineralization detection. Intense staining was revealed in I-PTH cells in comparison with C-PTH plates. The data obtained by monolayer cultures histological staining were confirmed by PCR analysis.

Extracellular Matrix Deposition in Engineered Micromass Cartilage Pellet Cultures: Measurements and Modelling

This article explores possible mechanisms governing extracellular matrix deposition in engineered cartilaginous cell pellets. A theoretical investigation is carried out alongside an experimental study measuring proteoglycan and collagen volume fractions within murine chondrogenic (ATDC-5) cell pellets. The simple mathematical model, which adopts a nutrient-dependent proteoglycan production rate, successfully reproduces the periphery-dominated proteoglycan deposition, characteristic of the growth pattern observed experimentally within pellets after 21 days of culture. The results suggest that this inhomogeneous proteoglycan production is due to nutrient deficiencies at the pellet centre. Our model analysis further indicates that a spatially uniform distribution of proteoglycan matrix could be maintained by initiating the culture process with a smaller-sized pellet. Finally, possible extensions are put forward with an aim to improve the model predictions for the early behaviour, where different mechanisms appear to dominate the matrix production within the pellets.

Cartilage Derived from Bone Marrow Mesenchymal Stem Cells Expresses Lubricin In Vitro and In Vivo

OBJECTIVE

Lubricin expression in the superficial cartilage will be a crucial factor in the success of cartilage regeneration. Mesenchymal stem cells (MSCs) are an attractive cell source and the use of aggregates of MSCs has some advantages in terms of chondrogenic potential and efficiency of cell adhesion. Lubricin expression in transplanted MSCs has not been fully elucidated so far. Our goals were to determine (1) whether cartilage pellets of human MSCs expressed lubricin in vitro chondrogenesis, (2) whether aggregates of human MSCs promoted lubricin expression, and (3) whether aggregates of MSCs expressed lubricin in the superficial cartilage after transplantation into osteochondral defects in rats.

METHODS

For in vitro analysis, human bone marrow (BM) MSCs were differentiated into cartilage by pellet culture, and also aggregated using the hanging drop technique. For an animal study, aggregates of BM MSCs derived from GFP transgenic rats were transplanted to the osteochondral defect in the trochlear groove of wild type rat knee joints. Lubricin expression was mainly evaluated in differentiated and regenerated cartilages.

RESULTS

In in vitro analysis, lubricin was detected in the superficial zone of the pellets and conditioned medium. mRNA expression of Proteoglycan4 (Prg4), which encodes lubricin, in pellets was significantly higher than that of undifferentiated MSCs. Aggregates showed different morphological features between the superficial and deep zone, and the Prg4 mRNA expression increased after aggregate formation. Lubricin was also found in the aggregate. In a rat study, articular cartilage regeneration was significantly better in the MSC group than in the control group as shown by macroscopical and histological analysis. The transmission electron microscope showed that morphology of the superficial cartilage in the MSC group was closer to that of the intact cartilage than in the control group. GFP positive cells remained in the repaired tissue and expressed lubricin in the superficial cartilage.

CONCLUSION

Cartilage derived from MSCs expressed lubricin protein both in vitro and in vivo. Aggregation promoted lubricin expression of MSCs in vitro and transplantation of aggregates of MSCs regenerated cartilage including the superficial zone in a rat osteochondral defect model. Our results indicate that aggregated MSCs could be clinically relevant for therapeutic approaches to articular cartilage regeneration with an appropriate superficial zone in the future.

Retinoic Acid Ameliorates Pancreatic Fibrosis and Inhibits the Activation of Pancreatic Stellate Cells in Mice with Experimental Chronic Pancreatitis via Suppressing the Wnt/β-Catenin Signaling Pathway

Pancreatic fibrosis, a prominent feature of chronic pancreatitis (CP), induces persistent and permanent damage in the pancreas. Pancreatic stellate cells (PSCs) provide a major source of extracellular matrix (ECM) deposition during pancreatic injury, and persistent activation of PSCs plays a vital role in the progression of pancreatic fibrosis. Retinoic acid (RA), a retinoid, has a broad range of biological functions, including regulation of cell differentiation and proliferation, attenuating progressive fibrosis of multiple organs. In the present study, we investigated the effects of RA on fibrosis in experimental CP and cultured PSCs. CP was induced in mice by repetitive cerulein injection in vivo, and mouse PSCs were isolated and activated in vitro. Suppression of pancreatic fibrosis upon administration of RA was confirmed based on reduction of histological damage, α-smooth muscle actin (α-SMA) expression and mRNA levels of β-catenin, platelet-derived growth factor (PDGF)-Rβ transforming growth factor (TGF)-βRII and collagen 1α1 in vivo. Wnt 2 and β-catenin protein levels were markedly down-regulated, while Axin 2 expression level was up-regulated in the presence of RA, both in vivo and in vitro. Nuclear translation of β-catenin was significantly decreased following RA treatment, compared with cerulein-induced CP in mice and activated PSCs. Furthermore, RA induced significant PSC apoptosis, inhibited proliferation, suppressed TCF/LEF-dependent transcriptional activity and ECM production of PSC via down-regulation of TGFβRII, PDGFRβ and collagen 1α1 in vitro. These results indicate a critical role of the Wnt/β-catenin signaling pathway in RA-induced effects on CP and PSC regulation and support the potential of RA as a suppressor of pancreatic fibrosis in mice.

miR-599 Inhibits Vascular Smooth Muscle Cells Proliferation and Migration by Targeting TGFB2

Aberrant proliferation and migration of vascular smooth muscle cells (VSMCs) play a crucial role in the pathogenesis of cardiovascular diseases including coronary heart disease, restenosis and atherosclerosis. MicroRNAs are a class of small, non-coding and endogenous RNAs that play critical roles in VSMCs function. In this study, we showed that PDGF-bb, as a stimulant, promoted VSMCs proliferation and suppressed the expression of miR-599. Moreover, overexpression of miR-599 inhibited VSMCs proliferation and also suppressed the PCNA and ki-67 expression. In addition, we demonstrated that ectopic expression of miR-599 repressed the VSMCs migration. We also showed that miR-599 inhibited type I collagen, type V collagen and proteoglycan expression. Furthermore, we identified TGFb2 as a direct target gene of miR-599 in VSMCs. Overexpression of TGFb2 reversed miR-599-induced inhibition of VSMCs proliferation and type I collagen, type V collagen and proteoglycan expression. In conclusion, our findings suggest miR-599 plays a crucial role in controlling VSMCs proliferation and matrix gene expression by regulating TGFb2 expression.

Endocan of the maternal placenta tissue is increased in pre-eclampsia

PURPOSE

Pre-eclampsia (PE) is associated with intravascular inflammation and endothelial dysfunction. Interestingly, endocan plays a predominant role in the vascular inflammation and is considered as a biomarker of endothelial dysfunction. The aim of this study was to explore whether the endocan levels in serum and placenta were different between pregnant women with PE and the normal pregnancies.

METHODS

Total 22 patients, including 10 normal pregnant women and 12 patients with PE, were included in this study. Immunohistochemistry was used to evaluate the location of endocan. Then, the mRNA and protein levels of endocan in placenta were detected using qRT-PCR and western blotting. Serum endocan concentration was measured by ELISA.

RESULTS

Endocan protein was present in the human placenta, and the mRNA and protein levels of placenta tissues were elevated (P < 0.05) in the normal pregnancy with third trimester than those with first trimester. Furthermore, the expression of endocan mRNA and protein were increased in the placenta tissues of PE compared with in the normal pregnancy (P < 0.05); however, the endocan concentration of maternal serum did not have significant differences.

CONCLUSION

Endocan may play a role in the progression of pregnancy and has a potential to be a new marker for the detective of PE.

Decreased Zn(2+) Influx Underlies the Protective Role of Hypoxia in Rat Nucleus Pulposus Cells

Zn(2+) is an essential component of metalloproteinases, and is required for their activity in cartilage; however, the effect of Zn(2+) on nucleus pulposus (NP) cells has not been widely investigated. The aim of this paper was to investigate the effect of intracellular Zn(2+) concentration ([Zn(2+)]i) in hypoxia-induced regulation of metalloproteinases (MMPs) and extracellular matrix (ECM) production in NP cells. NP cells from Sprague-Dawley (SD) rats were cultured as monolayers or in alginate beads. [Zn(2+)]i was assayed by FluoZin-3 AM staining. Alcian Blue staining, immunochemistry, 1,9-dimethylmethylene blue (DMMB) assay, and real-time PCR were used to assay collagen II, proteoglycan, and COL2A1, MMP-13, and ADAMTS-5 mRNA expression. ZIP8, a main Zn(2+) transporter in chondrocytes, was assayed by immunochemistry and in Western blotting. Interleukin (IL)-1β- and ZnCl2-induced increases of [Zn(2+)]i were significantly inhibited by hypoxia. Hypoxia did not reverse a decline of ECM expression caused by IL-1β and ZnCl2 in monolayer cultures, but did significantly attenuate the decreases of proteoglycan, glycosaminoglycan (GAG), and COL2A1 mRNA expression following IL-1β and ZnCl2 treatment in alginate bead cultures. However, ZnCl2 inhibited the protective effect of hypoxia. Both an intracellular Zn(2+) chelator and hypoxia prevented the increase in MMP-13 mRNA expression. IL-1β and ZnCl2 treatment increased ZIP8 expression in NP cells, and hypoxia inhibited ZIP8 expression. In conclusion, decrease of Zn(2+) influx mediates the protective role of hypoxia on ECM and MMP-13 expression. Consequently, changes in intracellular Zn(2+) concentration maybe involved in intervertebral disc degeneration.

The mechanism of action for hyaluronic acid treatment in the osteoarthritic knee: a systematic review

BACKGROUND

Knee osteoarthritis (OA) is one of the leading causes of disability within the adult population. Current treatment options for OA of the knee include intra-articular (IA) hyaluronic acid (HA), a molecule found intrinsically within the knee joint that provides viscoelastic properties to the synovial fluid. A variety of mechanisms in which HA is thought to combat knee OA are reported in the current basic literature.

METHODS

We conducted a comprehensive literature search to identify currently available primary non-clinical basic science articles focussing on the mechanism of action of IA-HA treatment. Included articles were assessed and categorized based on the mechanism of action described within them. The key findings and conclusions from each included article were obtained and analyzed in aggregate with studies of the same categorical assignment.

RESULTS

Chondroprotection was the most frequent mechanism reported within the included articles, followed by proteoglycan and glycosaminoglycan synthesis, anti-inflammatory, mechanical, subchondral, and analgesic actions. HA-cluster of differentiation 44 (CD44) receptor binding was the most frequently reported biological cause of the mechanisms presented. High molecular weight HA was seen to be superior to lower molecular weight HA products. HA derived through a biological fermentation process is also described as having favorable safety outcomes over avian-derived HA products.

CONCLUSIONS

The non-clinical basic science literature provides evidence for numerous mechanisms in which HA acts on joint structures and function. These actions provide support for the purported clinical benefit of IA-HA in OA of the knee. Future research should not only focus on the pain relief provided by IA-HA treatment, but the disease modification properties that this treatment modality possesses as well.

Oligodendrocyte progenitor cells differentiation of nuclear transferred mouse embryonic stem cells

Central nervous system (CNS) injuries cause to variable disorders in people around the world without any decisive treatment. Use of embryonic stem cells (ESCs) would be helpful in repairing of neural system damages. Somatic cell nuclear transfer (SCNT) is a way for implanting ESCs with lowest possible rejection. In the present study, mouse nuclear transfers ESCs (ntESCs) ability in differentiation to oligodendrocyte progenitor cells (OPCs) was investigated by morphological study, RT&mdash;PCR and flow cytometry analysis. Bi&mdash;polar and tri&mdash;polar, OPCs were observed in stem cells cultured in differentiation medium after four weeks. Result of gene expression analysis demonstrated that differentiated stem cells were expressed most important OPCs related gene markers after differentiation period. Moreover, flow cytometry analysis carried out to confirm other results that showed differentiated stem cells significantly expressed NG2 and O4 as critical OPC surface markers. Taken together, it seems that mouse ntESCs showed highly potential for OPC differentiation and could be an appropriate candidate for stem cell therapies.

Xylosyltransferase II is the predominant isoenzyme which is responsible for the steady-state level of xylosyltransferase activity in human serum

In mammals, two active xylosyltransferase isoenzymes (EC 2.4.2.16) exist. Both xylosyltransferases I and II (XT-I and XT-II) catalyze the transfer of xylose from UDP-xylose to select serine residues in the proteoglycan core protein. Altered XT activity in human serum was found to correlate directly with various diseases such as osteoarthritis, systemic sclerosis, liver fibrosis, and pseudoxanthoma elasticum. To interpret the significance of the enzyme activity alteration observed in disease states it is important to know which isoenzyme is responsible for the XT activity in serum. Until now it was impossible for a specific measurement of XT-I or XT-II activity, respectively, because of the absence of a suitable enzyme substrate. This issue has now been solved and the following experimental study demonstrates for the first time, via the enzyme activity that XT-II is the predominant isoenzyme responsible for XT activity in human serum. The proof was performed using natural UDP-xylose as the xylose donor, as well as the artificial compound UDP-4-azido-4-deoxyxylose, which is a selective xylose donor for XT-I.

EPO promotes bone repair through enhanced cartilaginous callus formation and angiogenesis

Erythropoietin (EPO)/erythropoietin receptor (EPOR) signaling is involved in the development and regeneration of several non-hematopoietic tissues including the skeleton. EPO is identified as a downstream target of the hypoxia inducible factor-α (HIF-α) pathway. It is shown that EPO exerts a positive role in bone repair, however, the underlying cellular and molecular mechanisms remain unclear. In the present study we show that EPO and EPOR are expressed in the proliferating, pre-hypertrophic and hypertrophic zone of the developing mouse growth plates as well as in the cartilaginous callus of the healing bone. The proliferation rate of chondrocytes is increased under EPO treatment, while this effect is decreased following siRNA mediated knockdown of EPOR in chondrocytes. EPO treatment increases biosynthesis of proteoglycan, accompanied by up-regulation of chondrogenic marker genes including SOX9, SOX5, SOX6, collagen type 2, and aggrecan. The effects are inhibited by knockdown of EPOR. Blockage of the endogenous EPO in chondrocytes also impaired the chondrogenic differentiation. In addition, EPO promotes metatarsal endothelial sprouting in vitro. This coincides with the in vivo data that local delivery of EPO increases vascularity at the mid-stage of bone healing (day 14). In a mouse femoral fracture model, EPO promotes cartilaginous callus formation at days 7 and 14, and enhances bone healing at day 28 indexed by improved X-ray score and micro-CT analysis of microstructure of new bone regenerates, which results in improved biomechanical properties. Our results indicate that EPO enhances chondrogenic and angiogenic responses during bone repair. EPO's function on chondrocyte proliferation and differentiation is at least partially mediated by its receptor EPOR. EPO may serve as a therapeutic agent to facilitate skeletal regeneration.

Mesenchymal precursor cells maintain the differentiation and proliferation potentials of breast epithelial cells

INTRODUCTION

Stromal-epithelial interactions play a fundamental role in tissue homeostasis, controlling cell proliferation and differentiation. Not surprisingly, aberrant stromal-epithelial interactions contribute to malignancies. Studies of the cellular and molecular mechanisms underlying these interactions require ex vivo experimental model systems that recapitulate the complexity of human tissue without compromising the differentiation and proliferation potentials of human primary cells.

METHODS

We isolated and characterized human breast epithelial and mesenchymal precursors from reduction mammoplasty tissue and tagged them with lentiviral vectors. We assembled heterotypic co-cultures and compared mesenchymal and epithelial cells to cells in corresponding monocultures by analyzing growth, differentiation potentials, and gene expression profiles.

RESULTS

We show that heterotypic culture of non-immortalized human primary breast epithelial and mesenchymal precursors maintains their proliferation and differentiation potentials and constrains their growth. We further describe the gene expression profiles of stromal and epithelial cells in co-cultures and monocultures and show increased expression of the tumor growth factor beta (TGFβ) family member inhibin beta A (INHBA) in mesenchymal cells grown as co-cultures compared with monocultures. Notably, overexpression of INHBA in mesenchymal cells increases colony formation potential of epithelial cells, suggesting that it contributes to the dynamic reciprocity between breast mesenchymal and epithelial cells.

CONCLUSIONS

The described heterotypic co-culture system will prove useful for further characterization of the molecular mechanisms mediating interactions between human normal or neoplastic breast epithelial cells and the stroma, and will provide a framework to test the relevance of the ever-increasing number of oncogenomic alterations identified in human breast cancer.

[Involvement of Smad pathway in proteoglycan 4 expression induced by hydrostatic pressure in temporomandibular synovial fibroblasts]

OBJECTIVE

To examine the expression of proteoglycan 4 (PRG-4) induced by hydrostatic pressure in rat temporomandibular synovial fibroblasts and investigate the possible mechanism.

METHODS

The cultured rat temporomandibular synovial fibroblasts were subjected to 100 kPa magnitude intermittent hydrostatic pressure (IHP) at frequency of 4 h/day, and the static group served as control. The expressions of Smad pathway proteins and p38MAPK pathway proteins were analyzed by Western blot and immunofluorescence staining. Then the cells were incubated with SB431542, the inhibitor of transforming growth factor (TGF)-β receptor. Western blot and reverse transcription PCR were used to detect the PRG-4 expression after 72 h.

RESULTS

The expression of phosphorylated Smad-2 and phosphorylated Smad-3 were increased after 1 h of IHP, reaching a maximum after 2 h and 4 h of IHP, respectively.However, the protein content of phosphorylated p38 did not vary significantly. In addition, IHP induced nuclear translocation of Smad-2/-3, and the immunofluorescence staining signal intensity markedly increased (24.11 ± 4.70)(P < 0.05). The levels of PRG-4 mRNA were significantly increased by IHP (1.48 ± 0.08)(P < 0.05). Treatment of cells with SB431542 could decrease the expression of PRG-4 mRNA significantly after IHP (0.47 ± 0.05)(P < 0.05). In addition, SB431542 inhibited the expression of PRG-4 protein induced by IHP.

CONCLUSIONS

Smad signal acts as an essential signal pathway to regulate PRG-4 expression induced by IHP.

[Chondrocyte microenvironment and application of microfluidic chips in constructing chondrocyte microenvironment]

OBJECTIVE

To review the chondrocyte survival microenvironment and the research progress of the application of microfluidic chips in constructing the chondrocyte microenvironment.

METHODS

Recent literature about the role of microenvironment in the regulation of chondrocytes and the application of microfluidic chips in constructing the chondrocyte microenvironment was reviewed and analyzed.

RESULTS

Regulating the microenvironment of chondrocyte mainly involves extracellular matrix microenvironment, mechanical microenvironment, electric microenvironment, and hypoxic microenvironment. Currently, the related research of chondrocyte microenvironment based on microfluidic system mainly involves biochemical stimuli, mechanical stimuli, production of biomimetic scaffold materials, and so on.

CONCLUSION

It will be helpful for constructing cartilage tissue being closer to the physiological function in the future to deeply understand chondrocyte survival environment and to mimic the microenvironment in vivo required by chondrocyte development as possible by using microfluidic chips.

Upregulation of endocan by Epstein-Barr virus latent membrane protein 1 and its clinical significance in nasopharyngeal carcinoma

Endocan (or called Esm-1) has been shown to have tumorigenic activities and its expression is associated with poor prognosis in various cancers. Latent membrane protein 1 (LMP1) is an Epstein-Barr virus (EBV)-encoded oncoprotein and has been shown to play an important role in the pathogenesis of EBV-associated nasopharyngeal carcinoma (NPC). To further understand the role of LMP1 in the pathogenesis of NPC, microarray analysis of LMP1-regulated genes in epithelial cells was performed. We found that endocan was one of the major cellular genes upregulated by LMP1. This induction of endocan by LMP1 was confirmed in several epithelial cell lines including an NPC cell line. Upregulation of endocan by LMP1 was found to be mediated through the CTAR1 and CTAR2 domains of LMP1 and through the LMP1-activated NF-κB, MEK-ERK and JNK signaling pathways. To study whether endocan was expressed in NPC and whether endocan expression was associated with LMP1 expression in NPC, the expression of endocan and LMP1 in tumor tissues from 42 NPC patients was evaluated by immunohistochemistry. Expression of endocan was found in 52% of NPC specimens. Significant correlation between LMP1 and endocan expression was observed (p<0.0001). Moreover, NPC patients with endocan expression were found to have a shorter survival than NPC patients without endocan expression (p=0.0104, log-rank test). Univariate and Multivariate analyses revealed that endocan was a potential prognostic factor for NPC. Finally, we demonstrated that endocan could stimulate the migration and invasion ability of endothelial cells and this activity of endocan was dependent on the glycan moiety and the phenylalanine-rich region of endocan. Together, these studies not only identify a new molecular marker that may predict the survival of NPC patients but also provide a new insight to the pathogenesis of NPC.

Hereditary multiple exostosis

Hereditary multiple exostosis is an intriguing genetic condition with a clinical impact in the field of orthopaedics, paediatrics and oncology. In this review we highlight the current knowledge about this condition from a clinical and scientific point of view. This gives us more insight into the molecular mechanisms and current models on which therapeutic agents are based. It allows for a multidisciplinary approach to the management of this complex condition. There is currently no exact pathological model that can accurately describe all the findings in the research on Hereditary Multiple Exostosis. Promising treatments with blocking agents are currently under investigation.

Transient hypoxia improves matrix properties in tissue engineered cartilage

Adult articular cartilage is a hypoxic tissue, with oxygen tension ranging from <10% at the cartilage surface to <1% in the deepest layers. In addition to spatial gradients, cartilage development is also associated with temporal changes in oxygen tension. However, a vast majority of cartilage tissue engineering protocols involves cultivation of chondrocytes or their progenitors under ambient oxygen concentration (21% O(2)), that is, significantly above physiological levels in either developing or adult cartilage. Our study was designed to test the hypothesis that transient hypoxia followed by normoxic conditions results in improved quality of engineered cartilaginous ECM. To this end, we systematically compared the effects of normoxia (21% O(2) for 28 days), hypoxia (5% O(2) for 28 days) and transient hypoxia--reoxygenation (5% O(2) for 7 days and 21% O(2) for 21 days) on the matrix composition and expression of the chondrogenic genes in cartilage constructs engineered in vitro. We demonstrated that reoxygenation had the most effect on the expression of cartilaginous genes including COL2A1, ACAN, and SOX9 and increased tissue concentrations of amounts of glycosaminoglycans and type II collagen. The equilibrium Young's moduli of tissues grown under transient hypoxia (510.01 ± 28.15 kPa) and under normoxic conditions (417.60 ± 68.46 kPa) were significantly higher than those measured under hypoxic conditions (279.61 ± 20.52 kPa). These data suggest that the cultivation protocols utilizing transient hypoxia with reoxygenation have high potential for efficient cartilage tissue engineering, but need further optimization in order to achieve higher mechanical functionality of engineered constructs.

The paratenon contributes to scleraxis-expressing cells during patellar tendon healing

The origin of cells that contribute to tendon healing, specifically extrinsic epitenon/paratenon cells vs. internal tendon fibroblasts, is still debated. The purpose of this study is to determine the location and phenotype of cells that contribute to healing of a central patellar tendon defect injury in the mouse. Normal adult patellar tendon consists of scleraxis-expressing (Scx) tendon fibroblasts situated among aligned collagen fibrils. The tendon body is surrounded by paratenon, which consists of a thin layer of cells that do not express Scx and collagen fibers oriented circumferentially around the tendon. At 3 days following injury, the paratenon thickens as cells within the paratenon proliferate and begin producing tenascin-C and fibromodulin. These cells migrate toward the defect site and express scleraxis and smooth muscle actin alpha by day 7. The thickened paratenon tissue eventually bridges the tendon defect by day 14. Similarly, cells within the periphery of the adjacent tendon struts express these markers and become disorganized. Cells within the defect region show increased expression of fibrillar collagens (Col1a1 and Col3a1) but decreased expression of tenogenic transcription factors (scleraxis and mohawk homeobox) and collagen assembly genes (fibromodulin and decorin). By contrast, early growth response 1 and 2 are upregulated in these tissues along with tenascin-C. These results suggest that paratenon cells, which normally do not express Scx, respond to injury by turning on Scx and assembling matrix to bridge the defect. Future studies are needed to determine the signaling pathways that drive these cells and whether they are capable of producing a functional tendon matrix. Understanding this process may guide tissue engineering strategies in the future by stimulating these cells to improve tendon repair.

Tenocytes of chronic rotator cuff tendon tears can be stimulated by platelet-released growth factors

BACKGROUND

Bone-to-tendon healing after rotator cuff repairs is mainly impaired by poor tissue quality. The tenocytes of chronic rotator cuff tendon tears are not able to synthesize normal fibrocartilaginous extracellular matrix (ECM). We hypothesized that in the presence of platelet-released growth factors (PRGF), tenocytes from chronically retracted rotator cuff tendons proliferate and synthesize the appropriate ECM proteins.

MATERIALS AND METHODS

Tenocytes from 8 patients with chronic rotator cuff tears were cultured for 4 weeks in 2 different media: standard medium (Iscove's Modified Dulbecco's Media + 10% fetal calf serum + 1% nonessential amino acids + 0.5 μg/mL ascorbic acid) and media with an additional 10% PRGF. Cell proliferation was assessed at 7, 14, 21, and 28 days. Messenger (m)RNA levels of collagens I, II, and X, decorin, biglycan, and aggrecan were analyzed using real time reverse-transcription polymerase chain reaction. Immunocytochemistry was also performed.

RESULTS

The proliferation rate of tenocytes was significantly higher at all time points when cultured with PRGF. At 21 days, the mRNA levels for collagens I, II, and X, decorin, aggrecan, and biglycan were significantly higher in the PRGF group. The mRNA data were confirmed at protein level by immunocytochemistry.

CONCLUSIONS

PRGFs enhance tenocyte proliferation in vitro and promote synthesis of ECM to levels similar to those found with insertion of the normal human rotator cuffs.

CLINICAL RELEVANCE

Biologic augmentation of repaired rotator cuffs with PRGF may enhance the properties of the repair tissue. However, further studies are needed to determine if application of PRGF remains safe and effective in long-term clinical studies.

LEVEL OF EVIDENCE

Basic Science Study, Cell Biology.

Regulation of xylosyltransferase I gene expression by interleukin 1β in human primary chondrocyte cells: mechanism and impact on proteoglycan synthesis

Xylosyltransferase I (XT-I) is an essential enzyme of proteoglycan (PG) biosynthesis pathway catalyzing the initial and rate-limiting step in glycosaminoglycan chain assembly. It plays a critical role in the regulation of PG synthesis in cartilage; however, little is known about underlying mechanism. Here, we provide evidence that, in human primary chondrocytes, IL-1β regulates XT-I gene expression into an early phase of induction and a late phase of down-regulation. Based on promoter deletions, the region up to -850 bp was defined as a major element of XT-I gene displaying both constitutive and IL-1β-regulated promoter activity. Point mutation and signaling analyses revealed that IL-1β-induced promoter activity is achieved through AP-1 response elements and mediated by SAP/JNK and p38 signaling pathways. Transactivation and chromatin immunoprecipitation assays indicated that AP-1 is a potent transactivator of XT-I promoter and that IL-1β-induced activity is mediated through increased recruitment of AP-1 to the promoter. Finally, we show that Sp3 is a repressor of XT-I promoter and bring evidence that the repressive effect of IL-1β during the late phase is mediated through Sp3 recruitment to the promoter. This suggests that modulation of Sp3 in cartilage could prevent IL-1β inhibition of PG synthesis and limit tissue degradation.

Characterizing the effects of VPA, VC and RCCS on rabbit keratocytes onto decellularized bovine cornea

To investigate the morphological and growth characteristics of rabbit keratocytes when cultured on decellularized cornea under simulate microgravity (SMG) rotary cell culture system (RCCS) and static culture or in plastic culture supplemented with small molecules of valproic acid (VPA) and vitamin C (VC). Bovine corneas were firstly decellularized with Triton X-100 and NH(4)OH and through short-term freezing process. Then cell count kit-8 (CCK-8) and flow cytometry were used to test the effects of VPA and VC on the proliferation, cell cycle and apoptosis of rabbit keratocytes. Hematoxylin-eosin (H&E) staining and scanning electron microscopy (SEM) imaging showed that cells were eliminated in the decellularized bovine corneas. The proliferation of cultured keratocytes was promoted by VPA and VC in the cell proliferation assay. VPA and VC moderately decreased the number of apoptotic cells and obviously promoted cell-cycle entrance of keratocytes. Rabbit keratocytes in plastic displayed spindle shape and rare interconnected with or without VPA and VC. Cells revealed dendritic morphology and reticular cellular connections when cultured on the carriers of decellularized corneas supplemented with VPA and VC even in the presence of 10% fetal bovine serum (FBS). When cultured in RCCS supplemented with VPA, VC and 10% FBS, keratocytes displayed round shape with many prominences and were more prone to grow into the pores of carriers with aggregation. Reverse transcription-polymerase chain reaction (RT-PCR) analysis proved that the keratocytes cultured on decellularized bovine cornea under SMG with VPA and VC expressed keratocan and lumican. Keratocytes cultured on plastic expressed lumican but not keratocan. Immunofluorescence identification revealed that cells in all groups were positively immunostained for vimentin. Keratocytes on decellularized bovine cornea under SMG or in static culture were positively immunostained for keratocan and lumican. Thus, we reasonably made a conclusion that the combination of VPA, VC, RCCS and decellularized corneal carriers provide a good condition for keratocytes to well grow. Keratocytes can be manipulated to be aggregates or physiological morphological growth in vitro, which are important for the research of corneal stem cells and corneal tissue engineering.

Effect of fucoidan extracted from mozuku on experimental cartilaginous tissue injury

We investigated the effect of fucoidan, a sulfated polysaccharide, on acceleration of healing of experimental cartilage injury in a rabbit model. An injured cartilage model was surgically created by introduction of three holes, one in the articular cartilage of the medial trochlea and two in the trochlear sulcus of the distal femur. Rabbits in three experimental groups (F groups) were orally administered fucoidan of seven different molecular weights (8, 50, 146, 239, 330, 400, or 1000 kD) for 3 weeks by screening. Control (C group) rabbits were provided water ad libitum. After the experimental period, macroscopic examination showed that the degree of filling in the fucoidan group was higher than that in the C group. Histologically, the holes were filled by collagen fiber and fibroblasts in the C group, and by chondroblasts and fibroblasts in the F groups. Image analysis of Alcian blue- and safranin O-stained F-group specimens showed increased production of glycosaminoglycans (GAGs) and proteoglycans (PGs), respectively. Some injured holes were well repaired both macroscopically and microscopically and were filled with cartilage tissues; cartilage matrices such as PGs and GAGs were produced in groups F 50, F 146, and F 239. Thus, fucoidan administration enhanced morphologically healing of cartilage injury.

Bismuth protects against arsenite-induced inhibition of proteoglycan synthesis in cultured vascular endothelial cells

Chronic ingestion of arsenic is associated with an increased risk of vascular disease such as atherosclerosis. Previously, we showed that arsenite inhibits the synthesis of general proteoglycans (PGs), which are key molecules in the progression of atherosclerosis, in vascular endothelial cells. In the present study, we investigated the effect of several metals on arsenite-induced inhibitory effect in endothelial cells. The results indicate that, after 24-hr incubation, the inhibition of PG synthesis caused by sodium arsenite was protected by bismuth nitrate but not zinc sulfate, manganese chloride, nickel chloride or cobalt chloride. The accumulation of arsenic in the cell layer was significantly decreased by bismuth after 12-hr incubation and that of bismuth was also decreased by arsenite. It was therefore suggested that the protective effect of bismuth against the inhibitory effect of arsenite on PG synthesis in vascular endothelial cells may be due, at least in part, to the decrease in cellular arsenic accumulation.

IL-4 alone and in combination with IL-10 protects against blood-induced cartilage damage

OBJECTIVE

It has been reported that interleukin (IL)-10 limits blood-induced cartilage damage. Our aim was to study the effect of IL-4 alone and in combination with IL-10 on blood-induced cartilage damage.

DESIGN

Healthy human full thickness cartilage explants were cultured for 4 days in the presence of 50% v/v blood. IL-4, IL-10, or a combination of both cytokines was added during blood exposure. Cartilage matrix turnover was determined after a recovery period; additionally cytokine production, chondrocyte apoptosis, and expression of the IL-4 and IL-10 receptors were analyzed directly after exposure.

RESULTS

Blood-induced damage to the cartilage matrix was limited by IL-4 in a dose-dependent way (P<0.05). Also IL-10 limited this damage, although to a lesser extent (P<0.03). The effect of IL-4 plus IL-10 was more pronounced and protective than IL-10 alone (P<0.05). Production of IL-1β and tumor necrosis factor (TNF)-α was limited by both IL-4 and IL-10 (P<0.05), but more strongly by IL-4. Blood-induced apoptosis of chondrocytes was limited by IL-4 and the combination, and not by IL-10 alone. No direct beneficial effect of IL-4 or IL-10 on cartilage was found, however, the chondrocyte receptor expression of both cytokine receptors was upregulated by exposure to blood.

CONCLUSIONS

This study demonstrates that IL-4 alone and in combination with IL-10 prevents blood-induced cartilage damage. Expectedly, anti-inflammatory effects on monocytes in the blood fraction and protective effects on chondrocytes are both involved. IL-4 in combination with IL-10 might be used to prevent blood-induced joint damage as a result of trauma or surgery.

Microarray profiling of diaphyseal bone of rats suffering from hypervitaminosis A

Vitamin A is the only known compound that produces spontaneous fractures in rats. In an effort to resolve the molecular mechanism behind this effect, we fed young male rats high doses of vitamin A and performed microarray analysis of diaphyseal bone with and without marrow after 1 week, i.e., just before the first fractures appeared. Of the differentially expressed genes in cortical bone, including marrow, 98% were upregulated. In contrast, hypervitaminotic cortical bone without marrow showed reduced expression of 37% of differentially expressed genes. Gene ontology (GO) analysis revealed that only samples containing bone marrow were associated with a GO term, which principally represented extracellular matrix. This is consistent with the histological findings of increased endosteal/marrow osteoblast number. Fourteen genes, including Cyp26b1, which is known to be upregulated by vitamin A, were selected and verified by real-time PCR. In addition, immunohistochemical staining of bone sections confirmed that the bone-specific molecule osteoadherin was upregulated. Further analysis of the major gene-expression changes revealed apparent augmented Wnt signaling in the sample containing bone marrow but reduced Wnt signaling in cortical bone. Moreover, induced expression of hypoxia-associated genes was found only in samples containing bone marrow. Together, these results highlight the importance of compartment-specific analysis of bone and corroborate previous observations of compartment-specific effects of vitamin A, with reduced activity in cortical bone but increased activity in the endosteal/marrow compartment. We specifically identify potential key osteoblast-, Wnt signaling-, and hypoxia-associated genes in the processes leading to spontaneous fractures.

Synthesis of neoproteoglycans using the transglycosylation reaction as a reverse reaction of endo-glycosidases

A method for the synthesis of carbohydrate chains (glycosaminoglycans) and their coupling to peptides was investigated using proteoglycans. Glycosidases generally catalyze a hydrolytic reaction, but can also mediate the reverse reaction, which in this case is a transglycosylation. In the transglycosylation reaction of bovine testicular hyaluronidase, which is an endoglycosidase, glycosaminoglycans (hyaluronan and chondroitin sulfates) release disaccharide (uronic acid-N-acetylhexosamine) moieties from non-reducing terminal sites, and then the liberated disaccharides are transferred immediately to the non-reducing termini of other glycosaminoglycan chains. Using such continuous reactions, it is possible to synthesize glycosaminoglycan chains according to a specific design. It then becomes possible to transfer glycosaminoglycan chains synthesized on a peptide to other peptides using the transglycosylation reaction of endo-β-xylosidase acting on the linkage region between a peptide and glycosaminoglycan chains of proteoglycans. We believe this approach will open a new field for the synthesis of homogeneous proteoglycans or their corresponding analogues.

Proteoglycans and cartilage repair

Repair of damaged articular cartilage in osteoarthritis (OA) is a clinical challenge. Because cartilage is an avascular and aneural tissue, normal mechanisms of tissue repair through recruitment of cells to the site of tissue destruction are not feasible. Proteoglycan (PG) depletion induced by the proinflammatory cytokine interleukin-1β, a principal mediator in OA, is a major factor in the onset and progression of joint destruction. Current symptomatic treatments of OA by anti-inflammatory drugs do not alter the progression of the disease. Various therapeutic strategies have been developed to antagonize the effect of proinflammatory cytokines. However, relatively few studies were conducted to stimulate anabolic activity, in an attempt to enhance cartilage repair. To this aim, a nonviral gene transfer strategy of glycosyltransferases responsible for PG synthesis has been developed and tested for its capacity to promote cartilage PG synthesis and deposition. Transfection of chondrocytes or cartilage explants by the expression vector for the glycosyltransferase β-1,3-glucuronosyltransferase-I (GlcAT-I) enhanced PG synthesis and deposition in the ECM by promoting the synthesis of chondroitin sulfate GAG chains of the cartilage matrix. This indicates that therapy mediated through GT gene delivery may constitute a new strategy for the treatment of OA.

Expression of the progenitor marker NG2/CSPG4 predicts poor survival and resistance to ionising radiation in glioblastoma

Glioblastoma (GBM) is a highly aggressive brain tumour, where patients respond poorly to radiotherapy and exhibit dismal survival outcomes. The mechanisms of radioresistance are not completely understood. However, cancer cells with an immature stem-like phenotype are hypothesised to play a role in radioresistance. Since the progenitor marker neuron-glial-2 (NG2) has been shown to regulate several aspects of GBM progression in experimental systems, we hypothesised that its expression would influence the survival of GBM patients. Quantification of NG2 expression in 74 GBM biopsies from newly diagnosed and untreated patients revealed that 50% express high NG2 levels on tumour cells and associated vessels, being associated with significantly shorter survival. This effect was independent of age at diagnosis, treatment received and hypermethylation of the O(6)-methylguanine methyltransferase (MGMT) DNA repair gene promoter. NG2 was frequently co-expressed with nestin and vimentin but rarely with CD133 and the NG2 positive tumour cells harboured genetic aberrations typical for GBM. 2D proteomics of 11 randomly selected biopsies revealed upregulation of an antioxidant, peroxiredoxin-1 (PRDX-1), in the shortest surviving patients. Expression of PRDX-1 was associated with significantly reduced products of oxidative stress. Furthermore, NG2 expressing GBM cells showed resistance to ionising radiation (IR), rapidly recognised DNA damage and effectuated cell cycle checkpoint signalling. PRDX-1 knockdown transiently slowed tumour growth rates and sensitised them to IR in vivo. Our data establish NG2 as an important prognostic factor for GBM patient survival, by mediating resistance to radiotherapy through induction of ROS scavenging enzymes and preferential DNA damage signalling.

The effect of proteoglycans inhibited on the neurotropic growth of salivary adenoid cystic carcinoma

OBJECTIVE

To evaluate the relationship between inhibition of proteoglycans which secreted by salivary adenoid cystic carcinoma cell line (SACC-83) and the neurotropic ability of the tumor cells.

METHODS

The expression vector of short hairpin RNA (shRNA-WJ4) targeting xylosyltransferase-I gene was constructed and transfected into SACC-83 cells (group SACC83-WJ4), shRNA-HK used as negative control was transfected into SACC-83 cells (group SACC-83-HK), SACC-83 cells without transfection was used as black control (group SACC-83). The xylosyltransferase-I gene expression was measured by real-time PCR. The content of proteoglycans was detected by Blyscan Assay Kit. The effect of down-regulated proteoglycans on the perineural invasion of nude mice was observed. All data were analyzed by the software spss 13.0.

RESULTS

The results showed that the transfected efficiency of shRNA was 43.3%. The expression of xylosyltransferase-I was inhibited by 43.0% 48 h after transfection of shRNA-WJ4. The content of proteoglycans was down-regulated by 30.25% 48 h after transfection. In the neurotropic experiment in vivo of nude mice, the rate of perineural invasion of group SACC-83-WJ4 was 33.33%, significantly lower than that of the negative control (100%) and the black control (100%) (P < 0.05).

CONCLUSION

Xylosyltransferase-I gene of SACC cells was silenced by RNA interference technology, proteoglycans secretion was reduced and neurotropic invasion behavior of SACC was inhibited obviously.

Changes in expression of proteoglycan core proteins and heparan sulfate enzymes in the developing and adult murine aorta

Proteoglycan core proteins are linked to four different classes of linear sugar chains referred to as glycosaminoglycans. Heparan sulfate constitutes one of these classes of glycosaminoglycans, and has been shown to be important in developmental processes as well as disease. We designed a low-density gene expression array to identify expression levels of heparan sulfate biosynthetic enzymes and proteoglycan core proteins in the aorta of late stage embryos (E18.5) and adult mice (12 weeks). Significant changes were found in mRNA expression of proteoglycan core proteins syndecan, glypican, decorin, perlecan, and versican from development to adulthood (n = 8, p < 0.05). Immunohistochemistry revealed a striking localization of both decorin and perlecan staining to the subendothelium in adult vessels, which differed from consistent staining of the endothelium, smooth muscle, and adventitia in development. Significant differences were also identified in the expression of the heparan sulfate modifying enzymes, glururonyl C5 epimerase, 2-O and 6-O sulfotransferases, and N-deacetylase/N sulfotransferases 1-3 (n = 8, p < 0.05). In conclusion, proteoglycan core proteins and heparan sulfate biosynthetic enzymes in the aorta undergo significant changes in their expression from development to adulthood. These findings may have important biological significance in the specific cell-defined roles of proteoglycan and heparan sulfate related targets in vascular development, maintenance, and response to various perturbations.

Transcriptional regulation of proteoglycans and glycosaminoglycan chain-synthesizing glycosyltransferases by UV irradiation in cultured human dermal fibroblasts

Various kinds of glycosaminoglycans (GAGs) and proteoglycans (PGs) have been known to be involved in structural and space-filling functions, as well as many physiological regulations in skin. To investigate ultraviolet (UV) radiation-mediated regulation of GAGs and PGs in cultured human dermal fibroblasts, transcriptional changes of many types of PGs and GAG chain-synthesizing enzymes at 18 hr after 75 mJ/cm(2) of UV irradiation were examined using quantitative real-time polymerase chain reaction methods. Hyaluronic acid synthase (HAS)-1, -2, and -3 and hyaluronidase-2 mRNA expressions were significantly increased by UV irradiation. Expressions of lumican, fibromodulin, osteoglycin, syndecan-2, perlecan, agrin, versican, decorin, and biglycan were significantly decreased by UV irradiation, while syndecan-1 was increased. Expressions of GAG chain-synthesizing glycosyltransferases, xylosyltransferase-1, β1,3-glucuronyltransferase-1, β1,4-galactosyltransferase-2, -4, exostosin-1, chondroitin polymerizing factor, and chondroitin sulfate synthase-3 were significantly reduced, whereas those of β1,3-galactosyltransferase-6, β1,4-galactosyltransferase-3, -7, β-1,3-N-acetylglucosaminyltran sferase-2, and -7 were increased by UV irradiation. Heparanase-1 mRNA expression was increased, but that of heparanase-2 was reduced by UV irradiation. Time-course investigation of representative genes showed consistent results. In conclusion, UV irradiation may increase hyaluronic acid production through HAS induction, and decrease other GAG productions through downregulation of PG core proteins and GAG chain-synthesizing glycosyltransferases in cultured human dermal fibroblasts.

Modulation of small leucine-rich proteoglycans (SLRPs) expression in the mouse uterus by estradiol and progesterone

BACKGROUND

We have previously demonstrated that four members of the family of small leucine-rich-proteoglycans (SLRPs) of the extracellular matrix (ECM), named decorin, biglycan, lumican and fibromodulin, are deeply remodeled in mouse uterine tissues along the estrous cycle and early pregnancy. It is known that the combined action of estrogen (E2) and progesterone (P4) orchestrates the estrous cycle and prepares the endometrium for pregnancy, modulating synthesis, deposition and degradation of various molecules. Indeed, we showed that versican, another proteoglycan of the ECM, is under hormonal control in the uterine tissues.

METHODS

E2 and/or medroxiprogesterone acetate (MPA) were used to demonstrate, by real time PCR and immunoperoxidase staining, respectively, their effects on mRNA expression and protein deposition of these SLRPs, in the uterine tissues.

RESULTS

Decorin and lumican were constitutively expressed and deposited in the ECM in the absence of the ovarian hormones, whereas deposition of biglycan and fibromodulin were abolished from the uterine ECM in the non-treated group. Interestingly, ovariectomy promoted an increase in decorin, lumican and fibromodulin mRNA levels, while biglycan mRNA conspicuously decreased. Hormone replacement with E2 and/or MPA differentially modulates their expression and deposition.

CONCLUSIONS

The patterns of expression of these SLRPs in the uterine tissues were found to be hormone-dependent and uterine compartment-related. These results reinforce the existence of subpopulations of endometrial fibroblasts, localized into distinct functional uterine compartments, resembling the organization into basal and functional layers of the human endometrium.

Serglycin is a theranostic target in nasopharyngeal carcinoma that promotes metastasis

Nasopharyngeal carcinoma (NPC) is known for its high-metastatic potential. Here we report the identification of the proteoglycan serglycin as a functionally significant regulator of metastasis in this setting. Comparative genomic expression profiling of NPC cell line clones with high- and low-metastatic potential revealed the serglycin gene (SRGN) as one of the most upregulated genes in highly metastatic cells. RNAi-mediated inhibition of serglycin expression blocked serglycin secretion and the invasive motility of highly metastatic cells, reducing metastatic capacity in vivo. Conversely, serglycin overexpression in poorly metastatic cells increased their motile behavior and metastatic capacity in vivo. Growth rate was not influenced by serglycin in either highly or poorly metastatic cells. Secreted but not bacterial recombinant serglycin promoted motile behavior, suggesting a critical role for glycosylation in serglycin activity. Serglycin inhibition was associated with reduced expression of vimentin but not other epithelial-mesenchymal transition proteins. In clinical specimens, serglycin expression was elevated significantly in liver metastases from NPC relative to primary NPC tumors. We evaluated the prognostic value of serglycin by immunohistochemical staining of tissue microarrays from 263 NPC patients followed by multivariate analyses. High serglycin expression in primary NPC was found to be an unfavorable independent indicator of distant metastasis-free and disease-free survival. Our findings establish that glycosylated serglycin regulates NPC metastasis via autocrine and paracrine routes, and that it serves as an independent prognostic indicator of metastasis-free survival and disease-free survival in NPC patients.

Gene expression profiling of connective tissue growth factor (CTGF) stimulated primary human tenon fibroblasts reveals an inflammatory and wound healing response in vitro

PURPOSE

The biologic relevance of human connective tissue growth factor (hCTGF) for primary human tenon fibroblasts (HTFs) was investigated by RNA expression profiling using affymetrix(TM) oligonucleotide array technology to identify genes that are regulated by hCTGF.

METHODS

Recombinant hCTGF was expressed in HEK293T cells and purified by affinity and gel chromatography. Specificity and biologic activity of hCTGF was confirmed by biosensor interaction analysis and proliferation assays. For RNA expression profiling HTFs were stimulated with hCTGF for 48h and analyzed using affymetrix(TM) oligonucleotide array technology. Results were validated by real time RT-PCR.

RESULTS

hCTGF induces various groups of genes responsible for a wound healing and inflammatory response in HTFs. A new subset of CTGF inducible inflammatory genes was discovered (e.g., chemokine [C-X-C motif] ligand 1 [CXCL1], chemokine [C-X-C motif] ligand 6 [CXCL6], interleukin 6 [IL6], and interleukin 8 [IL8]). We also identified genes that can transmit the known biologic functions initiated by CTGF such as proliferation and extracellular matrix remodelling. Of special interest is a group of genes, e.g., osteoglycin (OGN) and osteomodulin (OMD), which are known to play a key role in osteoblast biology.

CONCLUSIONS

This study specifies the important role of hCTGF for primary tenon fibroblast function. The RNA expression profile yields new insights into the relevance of hCTGF in influencing biologic processes like wound healing, inflammation, proliferation, and extracellular matrix remodelling in vitro via transcriptional regulation of specific genes. The results suggest that CTGF potentially acts as a modulating factor in inflammatory and wound healing response in fibroblasts of the human eye.

Transforming growth factor-β regulation of proteoglycan synthesis in vascular smooth muscle: contribution to lipid binding and accelerated atherosclerosis in diabetes

Atherosclerosis is accelerated in the setting of diabetes, but the factors driving this phenomenon remain elusive. Hyperglycemia leads to elevated levels of transforming growth factor (TGF)-β and TGF-β has been implicated as a factor in atherosclerosis. Given the established association between hyperglycemia and elevated TGF-β, it is plausible that elevated TGF-β levels in diabetes play a pathogenic role in the development of accelerated atherosclerosis. TGF-β is a potent regulator of extracellular matrix synthesis, including many actions on proteoglycan synthesis that lead to increased binding to low-density lipoprotein and therefore potentially increased lipid retention in the vessel wall and accelerated atherosclerosis. TGF-β signals through the canonical TGF-β receptor I-mediated phosphorylation of Smad transcription factors and TGF-β signaling is also known to involve, positively and negatively, interactions with the mitogen-activated protein kinase pathways. The focus of the present review is on the effects of TGF-β on proteoglycan synthesis in vascular smooth muscle and particularly the signaling pathways through which TGF-β exerts its effects, because those pathways may be therapeutic targets for the prevention of pathological modifications in the proteoglycan component of the vessel wall in the vascular diseases of diabetes.

Thymosin beta4 improves functional neurological outcome in a rat model of embolic stroke

Thymosin beta4 (Tbeta4) is a developmentally expressed 43-amino acid peptide that inhibits organization of the actin-cytoskeleton by sequestration of G-actin monomers. Tbeta4 improves cardiac function after myocardial infarction in adult mice and promotes healing properties in both dermal and corneal wounds. We tested the hypothesis that Tbeta4 improves functional neurological outcome in a rat model of embolic stroke.

EXPERIMENTAL PROCEDURES

Male Wistar rats (n=18) were subjected to embolic middle cerebral artery occlusion (MCAo). Tbeta4 (6 mg/kg, IP) was administered 24 h after MCAo and then every 3 days for four additional doses (n=9). Rats treated with saline were used as a control (n=9). The adhesive-removal test (ART) and modified Neurological Severity Score (mNSS) were performed to measure functional outcome. Rats were sacrificed 56 days after MCAo. Immunostaining was performed with antibodies against NG-2 (chondroitin sulfate proteoglycan), CNPase (2", 3"-cyclic nucleotide 3'-phosphodiesterase) to detect immature and mature oligodendrocytes. Neurofilament-H (NF-H) antibodies were used to detect axons while myelinated axons were identified with Bielschowsky/Luxol (B/L) Blue staining. EBA (endothelial barrier antigen) was used for detection of mature vessels.

RESULTS

Ischemic rats treated with Tbeta4 demonstrated a significant overall improvement (P<0.01) in the ART and the mNSS when compared to controls. Significant improvement was observed beginning at 14 and 35 days, respectively. Lesion volumes showed no significant differences between the two groups. Treatment with Tbeta4 increased myelinated axons and increased vessel density in the ischemic boundary (P<0.05) and augmented remyelination which was associated with an increase of oligodendrocyte progenitor cells (OPCs) and myelinating oligodendrocytes (P<0.05).

CONCLUSIONS

The present study suggests that Tbeta4 improves neurological functional outcome after embolic stroke in rats. Axonal remodeling from mobilization of OPCs is proposed as contributing to Tbeta4 induced functional improvement.