CD44-related chondroitin sulfate proteoglycan, a cell surface receptor implicated with tumor cell invasion, mediates endothelial cell migration on fibrinogen and invasion into a fibrin matrix

Chondroitinase as a therapeutic enzyme: Prospects and challenges

The chondroitinases (Chase) are bacterial lyases that specifically digest chondroitin sulfate and/or dermatan sulfate glycosaminoglycans via a β-elimination reaction and generate unsaturated disaccharides. In recent decades, these enzymes have attracted the attention of many researchers due to their potential applications in various aspects of medicine from the treatment of spinal cord injury to use as an analytical tool. In spite of this diverse spectrum, the application of Chase is faced with several limitations and challenges such as thermal instability and lack of a suitable delivery system. In the current review, we address potential therapeutic applications of Chase with emphasis on the challenges ahead. Then, we summarize the latest achievements to overcome the problems by considering the studies carried out in the field of enzyme engineering, drug delivery, and combination-based therapy.

The Glycosaminoglycan Side Chains and Modular Core Proteins of Heparan Sulphate Proteoglycans and the Varied Ways They Provide Tissue Protection by Regulating Physiological Processes and Cellular Behaviour

This review examines the roles of HS-proteoglycans (HS-PGs) in general, and, in particular, perlecan and syndecan as representative examples and their interactive ligands, which regulate physiological processes and cellular behavior in health and disease. HS-PGs are essential for the functional properties of tissues both in development and in the extracellular matrix (ECM) remodeling that occurs in response to trauma or disease. HS-PGs interact with a biodiverse range of chemokines, chemokine receptors, protease inhibitors, and growth factors in immune regulation, inflammation, ECM stabilization, and tissue protection. Some cell regulatory proteoglycan receptors are dually modified hybrid HS/CS proteoglycans (betaglycan, CD47). Neurexins provide synaptic stabilization, plasticity, and specificity of interaction, promoting neurotransduction, neurogenesis, and differentiation. Ternary complexes of glypican-1 and Robbo-Slit neuroregulatory proteins direct axonogenesis and neural network formation. Specific neurexin-neuroligin complexes stabilize synaptic interactions and neural activity. Disruption in these interactions leads to neurological deficits in disorders of functional cognitive decline. Interactions with HS-PGs also promote or inhibit tumor development. Thus, HS-PGs have complex and diverse regulatory roles in the physiological processes that regulate cellular behavior and the functional properties of normal and pathological tissues. Specialized HS-PGs, such as the neurexins, pikachurin, and Eyes-shut, provide synaptic stabilization and specificity of neural transduction and also stabilize the axenome primary cilium of phototoreceptors and ribbon synapse interactions with bipolar neurons of retinal neural networks, which are essential in ocular vision. Pikachurin and Eyes-Shut interactions with an α-dystroglycan stabilize the photoreceptor synapse. Novel regulatory roles for HS-PGs controlling cell behavior and tissue function are expected to continue to be uncovered in this fascinating class of proteoglycan.

CD44 Glycosylation as a Therapeutic Target in Oncology

The interaction of non-kinase transmembrane glycoprotein CD44 with ligands including hyaluronic acid (HA) is closely related to the occurrence and development of tumors. Changes in CD44 glycosylation can regulate its binding to HA, Siglec-15, fibronectin, TM4SF5, PRG4, FGF2, collagen and podoplanin and activate or inhibit c-Src/STAT3/Twist1/Bmi1, PI3K/AKT/mTOR, ERK/NF-κB/NANOG and other signaling pathways, thereby having a profound impact on the tumor microenvironment and tumor cell fate. However, the glycosylation of CD44 is complex and largely unknown, and the current understanding of how CD44 glycosylation affects tumors is limited. These issues must be addressed before targeted CD44 glycosylation can be applied to treat human cancers.

Single-cell adhesivity distribution of glycocalyx digested cancer cells from high spatial resolution label-free biosensor measurements

The glycocalyx is a cell surface sugar layer of most cell types that greatly influences the interaction of cells with their environment. Its components are glycolipids, glycoproteins, and oligosaccharides. Interestingly, cancer cells have a thicker glycocalyx layer compared to healthy cells, but to date, there has been no consensus in the literature on the exact role of cell surface polysaccharides and their derivatives in cellular adhesion and signaling. In our previous work we discovered that specific glycocalyx components of cancer cells regulate the kinetics and strength of adhesion on RGD (arginine-glycine-aspartic acid) peptide-coated surfaces [1]. Depending on the employed enzyme concentration digesting specific components both adhesion strengthening and weakening could be observed by monitoring the averaged behavior of thousands of cells. The enzyme chondroitinase ABC (ChrABC) was used to digest the chondroitin-4-sulfate, chondroitin-6-sulfate, and dermatan sulfate components in the glycocalyx of cancer cells. In the present work, a high spatial resolution label-free optical biosensor was employed to monitor the adhesivity of cancer cells both at the single-cell and population level. Population-level distributions of single-cell adhesivity were first recorded and analyzed when ChrABC was added to the adhering cells. At relatively low and high ChrABC concentrations subpopulations with remarkably large and weak adhesivity were identified. The changes in the adhesivity distribution due to the enzyme treatment were analyzed and the subpopulations most affected by the enzyme treatment were highlighted. The presented results open up new directions in glycocalyx related cell adhesion research and in the development of more meaningful targeted cancer treatments affecting adhesion.

F12 as a reliable diagnostic and prognostic biomarker associated with immune infiltration in papillary thyroid cancer

Objective: To explore the function of coagulation factor XII (F12) in papillary thyroid cancer (PTC).

Materials and Methods: We assessed F12 expression and its relationship with overall survival (OS) in various cancers using TIMER and TISIDB databases. Further, we evaluated the mRNA and protein expression levels of F12 in PTC via different bioinformatics tools. The receiver operating characteristic (ROC) curve was applied to determine the diagnostic value of F12 in PTC. Then, the Kaplan-Meier plotter and Cox regression analyses were performed to examine the prognostic significance of F12. The possible mechanism of F12 in PTC was investigated through enrichment analyses. Finally, the correlation between F12 expression and immune cell infiltration was analyzed using TCGA data.

Results: This study revealed the clinical significance of F12 in various cancers. Higher mRNA (P <0.001) and protein expressions of F12 were observed in PTC compared with normal tissues. Besides, F12 expression exhibited high diagnostic performance in PTC and its overexpression served as an independent predictor for the poor OS (P <0.05). Enrichment analyses results showed that F12 was mainly involved in metabolism-associated pathways. Additionally, F12 expression was significantly linked to immune cell infiltration levels, especially macrophage infiltration.

Conclusions: F12 might be a reliable diagnostic and prognostic biomarker for PTC. Moreover, F12 expression might affect the OS of PTC patients via regulating metabolic pathways.

Emerging therapeutic role of chondroitinase (ChABC) in neurological disorders and cancer

Abstract:

Proteoglycans are essential biomacromolecules that participate in matrix structure and organization, cell proliferation and migration, and cell surface signal transduction. However, their roles in physiology, particularly in CNS remain incompletely deciphered. Numerous studies highlight the elevated levels of chondroitin sulphate proteoglycans (CSPGs) in various diseases like cancers and neurological disorders like spinal cord injury (SCI), traumatic brain damage, neurodegenerative diseases, and are mainly implicated to hinder tissue repair. In such a context, chondroitinase ABC (ChABC), a therapeutic enzyme has shown immense hope to treat these diseases in several preclinical studies, primarily attributed to the digestion of the side chains of the proteoglycan chondroitin sulphate (CS) molecule. Despite extensive research, the progress in evolving the concept of therapeutic targeting of proteoglycans is still in its infancy. This review thus provides fresh insights into the emerging therapeutic applications of ChABC in various diseases apart from SCI and the underlying mechanisms.

Chondroitin sulfate-hybridized zein nanoparticles for tumor-targeted delivery of docetaxel

Chondroitin sulfate-hybridized zein nanoparticles (zein/CS NPs) were developed for targeted delivery of docetaxel, which exhibited mean diameters of 157.8 ± 3.6 nm and docetaxel encapsulation efficiency of 64.2 ± 1.9 %. Docetaxel was released from the NPs in a sustained manner (∼72 h), following first-order kinetics. The zein/CS NPs showed improved colloidal stability, maintaining the initial size in serum for 12 h. The pre-treatment of CS reduced the uptake efficiency of the NPs by 23 % in PC-3 cells, suggesting the involvement of CD44-mediated uptake mechanism. The NPs showed 2.79-fold lower IC₅₀ values than free docetaxel. Enhanced tumor accumulation of the NPs was confirmed in PC-3 xenograft mice by near-infrared fluorescence imaging (35.3-fold, versus free Cy5.5). The NPs exhibited improved pharmacokinetic properties (9.5-fold longer terminal half-life, versus free docetaxel) and anti-tumor efficacy comparable to Taxotere with negligible systemic toxicity, suggesting zein/CS NPs could be a promising nanoplatform for targeted cancer therapy.

Interpenetrating polymer networks of collagen, hyaluronic acid, and chondroitin sulfate as scaffolds for brain tissue engineering

Stem cells can provide neuro-protection and potentially neuro-replacement to patients suffering from traumatic brain injuries (TBI), with a practical option being delivery via engineered scaffolds. Collagen (Coll) and glycosaminoglycan (GAG) have been used as scaffolds for brain tissue engineering yet they often do not support cell differentiation and survival. In this study, we developed interpenetrating polymer network scaffolds comprising Coll, and incorporating two commonly found GAGs in the brain, chondroitin sulfate (CS) and/or hyaluronic acid (HA). We seeded these scaffolds with mouse neural stem cells from the subventricular zone (SVZ) niche. Compared to Coll-alone, all other substrates decreased the percent of nestin+ stem cells. Coll-CS-HA was more efficient at suppressing nestin expression than the other scaffolds; all SVZ cells lost nestin expression within 7 days of culture. In contrast to nestin, the percentage of microtubule associated protein 2 (MAP2+) neurons was greater in scaffolds containing, CS, HA or CS-HA, compared to Coll alone. Finally, Coll-CS increased the percentage of glial fibrillary acidic protein (GFAP+) astrocytes compared to Coll scaffolds. Overall, this work shows that Coll-HA and Coll-CS-HA scaffolds selectively enhance neurogenesis and may be advantageous in tissue engineering therapy for TBI. STATEMENT OF SIGNIFICANCE: Brain injury is devastating yet with few options for repair. Stem cells that reside in the subventricular zone (SVZ) only repair damage inefficiently due to poor control of their cellular progeny and unsuitable extracellular matrix substrates. To solve these problems, we have systematically generated collagen (Coll) scaffolds with interpenetrating polymer networks (IPN) of hyaluronic acid (HA) or chondroitin sulfate proteoglycans (CS) or both. The scaffolds had defined pore sizes, similar mechanical properties and all three stimulated neurogenesis, whereas only CS stimulated astrocyte genesis. Overall, this work suggests that Coll-HA and Coll-CS-HA scaffolds selectively enhance neurogenesis and may be advantageous in tissue engineering therapy for brain repair.

A Novel Splice Variant of HYAL-4 Drives Malignant Transformation and Predicts Outcome in Patients with Bladder Cancer

PURPOSE

Poor prognosis of patients with muscle-invasive bladder cancer that often metastasizes drives the need for discovery of molecular determinants of bladder cancer progression. Chondroitin sulfate proteoglycans, including CD44, regulate cancer progression; however, the identity of a chondroitinase (Chase) that cleaves chondroitin sulfate from proteoglycans is unknown. HYAL-4 is an understudied gene suspected to encode a Chase, with no known biological function. We evaluated HYAL-4 expression and its role in bladder cancer.

EXPERIMENTAL DESIGN

In clinical specimens, HYAL-4 wild-type (Wt) and V1 expression was evaluated by RT-qPCR, IHC, and/or immunoblotting; a novel assay measured Chase activity. Wt and V1 were stably expressed or silenced in normal urothelial and three bladder cancer cell lines. Transfectants were analyzed for stem cell phenotype, invasive signature and tumorigenesis, and metastasis in four xenograft models, including orthotopic bladder.

RESULTS

HYAL-4 expression, specifically a novel splice variant (V1), was elevated in bladder tumors; Wt expression was barely detectable. V1 encoded a truncated 349 amino acid protein that was secreted. In bladder cancer tissues, V1 levels associated with metastasis and cancer-specific survival with high efficacy and encoded Chase activity. V1 cleaved chondroitin-6-sulfate from CD44, increasing CD44 secretion. V1 induced stem cell phenotype, motility/invasion, and an invasive signature. CD44 knockdown abrogated these phenotypes. V1-expressing urothelial cells developed angiogenic, muscle-invasive tumors. V1-expressing bladder cancer cells formed tumors at low density and formed metastatic bladder tumors when implanted orthotopically.

CONCLUSIONS

Our study discovered the first naturally-occurring eukaryotic/human Chase and connected it to disease pathology, specifically cancer. V1-Chase is a driver of malignant bladder cancer and potential predictor of outcome in patients with bladder cancer.

Self-assembled formation of chondroitin sulfate-based micellar nanogel for curcumin delivery to breast cancer cells

Nanogel based drug delivery systems have been broadly used for cancer treatment. In this research, octadecylamine was grafted to chondroitin sulfate using three different mole ratios (10, 20, and 30) and named CS-ODA1, 2, and 3, respectively. The amide bond formation between chondroitin sulfate and octadecylamine was confirmed by 1H-nuclear magnetic resonance (HNMR) in the CS-ODA3 sample; therefore, further analysis was performed on this sample. Curcumin was loaded at defined Cur/CS-ODA ratios (5, 10 and 15%) and CS-ODA3 with 10% curcumin was selected for further experiments due to more entrapment efficiency (79.56% ± 5.56). In vitro release profile of the curcumin loaded nanogels showed >80% release after 70 h. In addition, the results of MTT analysis on the MCF-7 cell line showed almost no toxicity toward blank nanogels, while curcumin-loaded nanogels induced significant death after 24 h. In the end, analysis of the cell cycle using MCF-7 cells also confirmed the cytotoxicity of curcumin loaded nanogels. This study also showed that the presence of curcumin loaded chondroitin sulfate nanogels could successfully increase cellular uptake in comparison with free curcumin. The synthesized nanogels containing curcumin are expected to be effective for further studies in cancer treatment.

Cloning, Expression, and Characterization of a New Glycosaminoglycan Lyase from Microbacterium sp. H14

Glycosaminoglycan (GAG) lyase is an effective tool for the structural and functional studies of glycosaminoglycans and preparation of functional oligosaccharides. A new GAG lyase from Microbacterium sp. H14 was cloned, expressed, purified, and characterized, with a molecular weight of approximately 85.9 kDa. The deduced lyase HCLaseM belonged to the polysaccharide lyase (PL) family 8. Based on the phylogenetic tree, HCLaseM could not be classified into the existing three subfamilies of this family. HCLaseM showed almost the same enzyme activity towards hyaluronan (HA), chondroitin sulfate A (CS-A), CS-B, CS-C, and CS-D, which was different from reported GAG lyases. HCLaseM exhibited the highest activities to both HA and CS-A at its optimal temperature (35 °C) and pH (pH 7.0). HCLaseM was stable in the range of pH 5.0–8.0 and temperature below 30 °C. The enzyme activity was independent of divalent metal ions and was not obviously affected by most metal ions. HCLaseM is an endo-type enzyme yielding unsaturated disaccharides as the end products. The facilitated diffusion effect of HCLaseM is dose-dependent in animal experiments. These properties make it a candidate for further basic research and application.

The chondroitin sulfate moiety mediates thrombomodulin-enhanced adhesion and migration of vascular smooth muscle cells

BACKGROUND

Thrombomodulin (TM), a transmembrane glycoprotein highly expressed in endothelial cells (ECs), is a potent anticoagulant maintaining circulation homeostasis. Under inflammatory states, TM expression is drastically reduced in ECs while vascular smooth muscle cells (VSMCs) show a robust expression of TM. The functional role of TM in VSMCs remains elusive.

METHODS

We examined the role of TM in VSMCs activities in human aortic VSMCs stimulated with platelet-derived growth factor-BB (PDGF-BB). Using rat embryonic aorta-derived A7r5 VSMCs which do not express TM, the role of the chondroitin sulfate (CS) moiety of TM in VSMCs was delineated with cells expressing wild-type TM and the CS-devoid TM mutant.

RESULTS

Expression of TM enhanced cell migration and adhesion/spreading onto type I collagen, but had no effect on cell proliferation. Knocking down TM with short hairpin RNA reduced PDGF-stimulated adhesion and migration of human aortic VSMCs. In A7r5 cells, TM-mediated cell adhesion was eradicated by pretreatment with chondroitinase ABC which degrades CS moiety. Furthermore, the TM mutant (TM^{S490, 492A}) devoid of CS moiety failed to increase cell adhesion, spreading or migration. Wild-type TM, but not TM^{S490, 492A}, increased focal adhesion kinase (FAK) activation during cell adhesion, and TM-enhanced cell migration was abolished by a function-blocking anti-integrin β₁ antibody.

CONCLUSION

Chondroitin sulfate modification is required for TM-mediated activation of β₁-integrin and FAK, thereby enhancing adhesion and migration activity of VSMCs.

Anti-tumor Study of Chondroitin Sulfate-Methotrexate Nanogels

Self-assembly nanogels (NGs) were formed by bioconjugating methotrexate (MTX) with chondroitin sulfate (CS). MTX-CS NGs can greatly enhance the solubility and improve the delivery efficacy of MTX due to the CD44 binding property of CS. Vivo experiments revealed that MTX-CS NGs showed less toxicity than MTX. MTX-CS NGs can improve the anti-tumor effect while reducing the side effects of MTX. Due to their CD44 binding property, chondroitin sulfate-drug conjugates could be a promising and efficient platform for improving the solubility of sparingly soluble drug molecules as well as targeted delivery to cancer cells and tumor tissues.

Expression of CD44 standard form and variant isoforms in human bone marrow stromal cells

Human Bone Marrow Stromal Cells (hBMSCs) can migrate from bone marrow to injured tissues, where they may differentiate into different types of new cells for replacement of dysfunctional cells. CD44 plays an important role in stem cell movement. The expression distribution of CD44 standard form (CD44S) and CD44 variants (CD44V) is closely related to cell movement and tissue migration. The aim of this study was to evaluate the expressions of CD44S and CD44V in hBMSCs. The hBMSCs from four human subjects were cultured in vitro. Phenotypic properties were analyzed by flow cytometry, and adipocyte and osteoblast differentiations were evaluated at passage 4. The expressions of CD44S and CD44V were examined using quantitative real-time polymerase chain reaction (q-PCR). Results showed that hBMSCs were successfully cultured, with positive expressions of markers of mesenchymal cells (CD90, CD73, CD105), and negative expressions of markers of hematopoietic cells (CD34, CD45). The cultured hBMSCs can be induced to differentiate into adipocytes and osteoblasts. Q-PCR results showed that the expression of CD44S was significantly higher than the expressions of different CD44V isoforms in different samples. These results revealed significant differences in the distributions of CD44S and CD44V gene expressions, demonstrating a dominant CD44S expression in hBMCSs.

Carbohydrate-based amphiphilic nano delivery systems for cancer therapy

Nanoparticles (NPs) are novel drug delivery systems that have been attracting more and more attention in recent years, and have been used for the treatment of cancer, infection, inflammation and other diseases. Among the numerous classes of materials employed for constructing NPs, organic polymers are outstanding due to the flexibility of design and synthesis and the ease of modification and functionalization. In particular, NP based amphiphilic polymers make a great contribution to the delivery of poorly-water soluble drugs. For example, natural, biocompatible and biodegradable products like polysaccharides are widely used as building blocks for the preparation of such drug delivery vehicles. This review will detail carbohydrate based amphiphilic polymeric systems for cancer therapy. Specifically, it focuses on the nature of the polymer employed for the preparation of targeted nanocarriers, the synthetic methods, as well as strategies for the application and evaluation of biological activity. Applications of the amphiphilic polymer systems include drug delivery, gene delivery, photosensitizer delivery, diagnostic imaging and specific ligand-assisted cellular uptake. As a result, a thorough understanding of the relationship between chemical structure and biological properties facilitate the optimal design and rational clinical application of the resulting carbohydrate based nano delivery systems for cancer therapy.

Bioactive extracellular matrix fragments in lung health and disease

The extracellular matrix (ECM) is the noncellular component critical in the maintenance of organ structure and the regulation of tissue development, organ structure, and cellular signaling. The ECM is a dynamic entity that undergoes continuous degradation and resynthesis. In addition to compromising structure, degradation of the ECM can liberate bioactive fragments that cause cellular activation and chemotaxis of a variety of cells. These fragments are termed matrikines, and their cellular activities are sentinel in the development and progression of tissue injury seen in chronic lung disease. Here, we discuss the matrikines that are known to be active in lung biology and their roles in lung disease. We also consider the use of matrikines as disease markers and potential therapeutic targets in lung disease.

Hyaluronan as a therapeutic target in human diseases

Accumulation and turnover of extracellular matrix is a hallmark of tissue injury, repair and remodeling in human diseases. Hyaluronan is a major component of the extracellular matrix and plays an important role in regulating tissue injury and repair, and controlling disease outcomes. The function of hyaluronan depends on its size, location, and interactions with binding partners. While fragmented hyaluronan stimulates the expression of an array of genes by a variety of cell types regulating inflammatory responses and tissue repair, cell surface hyaluronan provides protection against tissue damage from the environment and promotes regeneration and repair. The interactions of hyaluronan and its binding proteins participate in the pathogenesis of many human diseases. Thus, targeting hyaluronan and its interactions with cells and proteins may provide new approaches to developing therapeutics for inflammatory and fibrosing diseases. This review focuses on the role of hyaluronan in biological and pathological processes, and as a potential therapeutic target in human diseases.

Spinal cord regeneration

Three theories of regeneration dominate neuroscience today, all purporting to explain why the adult central nervous system (CNS) cannot regenerate. One theory proposes that Nogo, a molecule expressed by myelin, prevents axonal growth. The second theory emphasizes the role of glial scars. The third theory proposes that chondroitin sulfate proteoglycans (CSPGs) prevent axon growth. Blockade of Nogo, CSPG, and their receptors indeed can stop axon growth in vitro and improve functional recovery in animal spinal cord injury (SCI) models. These therapies also increase sprouting of surviving axons and plasticity. However, many investigators have reported regenerating spinal tracts without eliminating Nogo, glial scar, or CSPG. For example, many motor and sensory axons grow spontaneously in contused spinal cords, crossing gliotic tissue and white matter surrounding the injury site. Sensory axons grow long distances in injured dorsal columns after peripheral nerve lesions. Cell transplants and treatments that increase cAMP and neurotrophins stimulate motor and sensory axons to cross glial scars and to grow long distances in white matter. Genetic studies deleting all members of the Nogo family and even the Nogo receptor do not always improve regeneration in mice. A recent study reported that suppressing the phosphatase and tensin homolog (PTEN) gene promotes prolific corticospinal tract regeneration. These findings cannot be explained by the current theories proposing that Nogo and glial scars prevent regeneration. Spinal axons clearly can and will grow through glial scars and Nogo-expressing tissue under some circumstances. The observation that deleting PTEN allows corticospinal tract regeneration indicates that the PTEN/AKT/mTOR pathway regulates axonal growth. Finally, many other factors stimulate spinal axonal growth, including conditioning lesions, cAMP, glycogen synthetase kinase inhibition, and neurotrophins. To explain these disparate regenerative phenomena, I propose that the spinal cord has evolved regenerative mechanisms that are normally suppressed by multiple extrinsic and intrinsic factors but can be activated by injury, mediated by the PTEN/AKT/mTOR, cAMP, and GSK3b pathways, to stimulate neural growth and proliferation.

Chondroitinase: A promising therapeutic enzyme

Even after 20 years of granting orphan status for chondroitinase by US FDA, there is no visible outcome in terms of clinical use. The reasons are many. One of them could be lack of awareness regarding the biological application of the enzyme. The biological activity of chondroitinase is due to its ability to act on chondroitin sulfate proteoglycans (CSPGs). CSPGs are needed for normal functioning of the body. An increase or decrease in the level of CSPGs results in various pathological conditions. Chondroitinase is useful in conditions where there is an increase in the level of CSPGs, namely spinal cord injury, vitreous attachment and cancer. Over the last decade, various animal studies showed that chondroitinase could be a good drug candidate. Research focusing on developing a suitable carrier system for delivering chondroitinase needs to be carried out so that pharmacological activity observed in vitro and preclinical studies could be translated to clinical use. Further studies on distribution of chondroitinase as well need to be focused so that chondroitinase with desired attributes could be discovered. The present review article discusses about various biological applications of chondroitinase, drug delivery systems to deliver the enzyme and distribution of chondroitinase among microbes.

Far from resolved: stromal cell-based iTRAQ research of muscle-invasive bladder cancer regarding heterogeneity

The aim of the present study was to globally characterize the cancer stroma expression profile of muscle-invasive bladder cancer in different metastatic risk groups and to discuss the decisive role of biological pathway change in cancer heterogeneity. Laser capture microdissection was employed to harvest purified muscle-invasive bladder cancer stromal cells derived from 30 clinical samples deriving from 3 different metastatic risk groups. Isobaric tags for relative and absolute quantitation (iTRAQ) and two-dimensional liquid chromatography tandem mass spectrometry (2D LC-MS/MS) were used to identify the differentially expressed proteins. Subsequently, the differentially expressed proteins were further analyzed by bioinformatics tools. After completing the above tasks, the proteins of interest were further compared with the published litterature. We identified 1,049 differentially expressed proteins by paired comparison (high risk vs. median, low risk and normal groups; median risk vs. low risk and normal groups, low risk vs. normal group; a total of 6 comparisons). A total of 510,549,548 proteins as significantly altered (ratio fold-change≥1.5 or ≤0.667 between the metastatic potential risk group and the normal group) were presented in the low/median/high metastatic risk group, respectively. Pathway analysis revealed that the differentially expressed proteins were mainly located in the Kyoto Encyclopedia of Genes and Genomes pathways, including focal adhesion pathway, systemic lupus erythematosus pathway and ECM-receptor interaction pathway. In addition, several proteins such as EXOC4, MYH10 and MMP-9 may serve as candidate biomarkers of muscle-invasive bladder cancer. Our study confirmed that stromal cells, an important part of the cancer tissue, are pivotal for regulating the heterogeneity of cancer. Common changes in biological pathways determined the malignant phenotype of muscle-invasive bladder cancer, and biomarker discovery should take into account both neoplastic cells and their corresponding stromata.

Sulfated glycosaminoglycan-based block copolymer: preparation of biocompatible chondroitin sulfate-b-poly(lactic acid) micelles

Despite a growing interest in amphiphilic polysaccharide-based diblock copolymers as functional polymeric drug delivery nanosystems, biologically relevant sulfated glycosaminoglycan systems were not yet investigated. Here, we report the synthesis and the self-assembly properties in water of chondroitin sulfate-b-poly(lactic acid) (CS-b-PLA(n)). The CS-b-PLA(n) were synthesized using click-grafting onto method implying reducing-end alkynation of low-molecular weight depolymerized CS (M(w) = 5000 g·mol(-1)) and azide-terminated functionalization of PLAn (M(w) = 6500 g·mol(-1) (n = 46) and M(w) = 1700 g·mol(-1) (n = 20)). The diblock copolymer self-assembled in water giving rise to spherical micelles that were characterized in solution using dynamic/static light scattering and at dry state by TEM technique. In vitro assays on healthy cells showed that at high concentrations, up to 10 μg·mL(-1), CS-b-PLA(n) were noncytotoxic. Those preliminary studies are promising in the perspective to use them as biocompatible nanovehicles for anticancer drug delivery.

Application of polysaccharides for surface modification of nanomedicines

Polysaccharides have been used in various biomedical applications due to availability and biocompatibility. In particular, polysaccharides have gained increasing interest in the development of functional nanomedicines as a component to provide a stealth function, improve interactions with target tissues or enable environment-responsive drug release. This review discusses recent advances in nanomedicine engineering based on polysaccharides with a specific emphasis on the rationale, applications and the remaining challenges.

The biology of CD44 and HCELL in hematopoiesis: the 'step 2-bypass pathway' and other emerging perspectives

PURPOSE OF REVIEW

The homing and egress of hematopoietic stem and progenitor cells (HSPCs) to and from marrow, respectively, and the proliferation and differentiation of HSPCs within marrow are complex processes critically regulated by the ordered expression and function of adhesion molecules that direct key cell-cell and cell-matrix interactions. The integral membrane molecule CD44, known primarily for its role in binding hyaluronic acid, is characteristically expressed on HSPCs. Conspicuously, human HSPCs uniquely display a specialized glycoform of CD44 known as hematopoietic cell E-/L-selectin ligand (HCELL), which is the most potent ligand for both E-selectin and L-selectin expressed on human cells. This review focuses on recent advances in our understanding of the biology of CD44 and HCELL in hematopoiesis.

RECENT FINDINGS

New data indicate that CD44-mediated events in hematopoiesis are more complex than previously imagined. Ex-vivo glycan engineering has established that HCELL serves as a 'bone marrow homing receptor'. Moreover, biochemical studies now show that CD44 forms bimolecular complexes with a variety of membrane proteins, one of which is VLA-4. Engagement of CD44 or of HCELL directly induces VLA-4 activation via G-protein-dependent signaling, triggering a 'step 2-bypass pathway' of cell migration, and extravascular lodgment, in absence of chemokine receptor engagement.

SUMMARY

Recent studies have further clarified the roles of CD44 and its glycoform HCELL in hematopoietic processes, providing key insights on how targeting these molecules may be beneficial in promoting hematopoiesis and in treating hematologic malignancies.

Effect of introduction of chondroitin sulfate into polymer-peptide conjugate responding to intracellular signals

We recently developed a novel tumor-targeted gene delivery system responding to hyperactivated intracellular signals. Polymeric carrier for gene delivery consists of hydrophilic neutral polymer as main chains and cationic peptide substrate for target enzyme as side chains, and was named polymer-peptide conjugate (PPC). Introduction of chondroitin sulfate (CS), which induces receptor-medicated endocytosis, into polymers mainly with a high cationic charge density such as polyethylenimine can increase tumor-targeted gene delivery. In the present study, we examined whether introduction of CS into PPC containing five cationic amino acids can increase gene expression in tumor cells. Size and zeta potential of plasmid DNA (pDNA)/PPC/CS complex were <200 nm and between -10 and -15 mV, respectively. In tumor cell experiments, pDNA/PPC/CS complex showed lower stability and gene regulation, compared with that of pDNA/PPC. Moreover, no difference in gene expression was identified between positive and negative polymer. These results were caused by fast disintegration of pDNA/PPC/CS complexes in the presence of serum. Thus, we suggest that introduction of negatively charged CS into polymers with a low charge density may lead to low stability and gene regulation of complexes.

The controlled photoactivity of nanoparticles derived from ionic interactions between a water soluble polymeric photosensitizer and polysaccharide quencher

In order to design a water soluble polymeric photosensitizer (WPS) with controllable photoactivity, a nano-photosensitizer (NPS) was prepared from a polyelectrolyte complex between polyethylene glycol-polyethylenimine-chlorine e6 conjugate (PEG-PEI-Ce6) and Black Hole Quencher-3 chondroitin sulfate conjugate (BHQ-3-CS). NPSs have a unimodal size distribution below 100 nm. Photoquenching of the NPS was dependent on the weight ratio of BHQ-3-CS/WPS. This phenomenon was maintained in a salt condition up to 300 mm, indicating that the photoactivity of the NPS disappears in the normal blood stream of the body. The quenched photoactivity was restored by the enzyme degradation of BHQ-3-CS after esterase treatment. In a HCT-116 (human colon cancer) cell test, the rapid cellular internalization of the NPS without any other ligands was observed by confocal imaging. Upon light irradiation after internalization, phototoxicity was detected via MTT colorimetric assay. Also, when the NPS was subcutaneously injected in both tumoral and normal regions of HCT-116 tumor-bearing mice, the fluorescence signal in the tumors rapidly increased compared to the normal region due to the enzymatic-triggered dissociation of the NPS in vivo. These results suggest that the NPS can provide both tumor diagnosis and therapy simultaneously, and has great potential for biological studies and clinical treatments of various tumors.

Differential use of chondroitin sulfate to regulate hyaluronan binding by receptor CD44 in Inflammatory and Interleukin 4-activated Macrophages

CD44 is a cell surface receptor for the extracellular matrix glycosaminoglycan hyaluronan and is involved in processes ranging from leukocyte recruitment to wound healing. In the immune system, the binding of hyaluronan to CD44 is tightly regulated, and exposure of human peripheral blood monocytes to inflammatory stimuli increases CD44 expression and induces hyaluronan binding. Here we sought to understand how mouse macrophages regulate hyaluronan binding upon inflammatory and anti-inflammatory stimuli. Mouse bone marrow-derived macrophages stimulated with tumor necrosis factor α or lipopolysaccharide and interferon-γ (LPS/IFNγ) induced hyaluronan binding by up-regulating CD44 and down-regulating chondroitin sulfation on CD44. Hyaluronan binding was induced to a lesser extent in interleukin-4 (IL-4)-activated macrophages despite increased CD44 expression, and this was attributable to increased chondroitin sulfation on CD44, as treatment with β-d-xyloside to prevent chondroitin sulfate addition significantly enhanced hyaluronan binding. These changes in the chondroitin sulfation of CD44 were associated with changes in mRNA expression of two chondroitin sulfotransferases, CHST3 and CHST7, which were decreased in LPS/IFNγ-stimulated macrophages and increased in IL-4-stimulated macrophages. Thus, inflammatory and anti-inflammatory stimuli differentially regulate the chondroitin sulfation of CD44, which is a dynamic physiological regulator of hyaluronan binding by CD44 in mouse macrophages.

Hyaluronan as an immune regulator in human diseases

Accumulation and turnover of extracellular matrix components are the hallmarks of tissue injury. Fragmented hyaluronan stimulates the expression of inflammatory genes by a variety of immune cells at the injury site. Hyaluronan binds to a number of cell surface proteins on various cell types. Hyaluronan fragments signal through both Toll-like receptor (TLR) 4 and TLR2 as well as CD44 to stimulate inflammatory genes in inflammatory cells. Hyaluronan is also present on the cell surface of epithelial cells and provides protection against tissue damage from the environment by interacting with TLR2 and TLR4. Hyaluronan and hyaluronan-binding proteins regulate inflammation, tissue injury, and repair through regulating inflammatory cell recruitment, release of inflammatory cytokines, and cell migration. This review focuses on the role of hyaluronan as an immune regulator in human diseases.

Novel glycosaminoglycan biosynthetic inhibitors affect tumor-associated angiogenesis

Heparan sulfate proteoglycans (HSPGs) are essential players in several steps of tumor-associated angiogenesis. As co-receptors for several pro-angiogenic factors such as VEGF and FGF, HSPGs regulate receptor-ligand interactions and play a vital role in signal transduction. Previously, we have employed an enzymatic strategy to show the importance of cell surface HSPGs in endothelial tube formation in vitro. We have recently found several fluoro-xylosides that can selectively inhibit proteoglycan synthesis in endothelial cells. The current study demonstrates that these fluoro-xylosides are effective inhibitors of endothelial tube formation in vitro using a matrigel based assay to simulate tumor-associated angiogenesis. These first generation scaffolds offer a promising stepping-stone to the discovery of more potent fluoro-xylosides that can effectively neutralize tumor growth.

Electrospun hyaluronate-collagen nanofibrous matrix and the effects of varying the concentration of hyaluronate on the characteristics of foreskin fibroblast cells

In this study we propose a novel electrospinning fabrication process for the production of a nanofibrous matrix composed of collagen and hyaluronate. This procedure utilized 1,1,1,3,3,3-hexafluoro-2-propanol and formic acid as a mixed solvent. Fluorescence microscopy photographs revealed that the resulting electrospun nanofibers contained both collagen and hyaluronate. The mean diameter of the composite nanofibrous matrix (as observed using scanning electron micrographs) was approximately 200nm; this dimension is similar to that of native fibrous protein within the extracellular matrix. The expression of proteinases (e.g. matrix metalloproteinases, MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have been implicated in epidermal repair during wound healing. Moreover, the characteristics of scarless wounds are known to be related to a decreased ratio of TIMP to MMP expression. In the present study the ratio of expression of TIMP1 to MMP1 was lower in foreskin fibroblast cells that were cultured on a hyaluronate-collagen composite nanofibrous matrix than in those cultured on an exclusively collagen nanofibrous matrix. This indicates that the hyaluronate-collagen composite nanofibrous matrix could potentially be used as a wound dressing for the regeneration of scarless skin.

Heparan sulfate proteoglycans: structure, protein interactions and cell signaling

Heparan sulfate proteoglycans are ubiquitously found at the cell surface and extracellular matrix in all the animal species. This review will focus on the structural characteristics of the heparan sulfate proteoglycans related to protein interactions leading to cell signaling. The heparan sulfate chains due to their vast structural diversity are able to bind and interact with a wide variety of proteins, such as growth factors, chemokines, morphogens, extracellular matrix components, enzymes, among others. There is a specificity directing the interactions of heparan sulfates and target proteins, regarding both the fine structure of the polysaccharide chain as well precise protein motifs. Heparan sulfates play a role in cellular signaling either as receptor or co-receptor for different ligands, and the activation of downstream pathways is related to phosphorylation of different cytosolic proteins either directly or involving cytoskeleton interactions leading to gene regulation. The role of the heparan sulfate proteoglycans in cellular signaling and endocytic uptake pathways is also discussed.

Clearance of dying cells and autoimmunity

Phagocytic clearance of apoptotic cells is an important physiologic homeostatic mechanism that is associated with non-inflammatory or anti-inflammatory sequalae. Disruption of the process of apoptotic cell clearance may contribute to development of a number of inflammatory and autoimmune diseases. In this review, we summarize the molecular pathways that have been suggested to account for phagocytic clearance of apoptotic cells. We discuss potential mechanisms for regulation of phagocytosis and the implications for development of autoimmunity.

Gene expression, biodistribution, and pharmacoscintigraphic evaluation of chondroitin sulfate-PEI nanoconstructs mediated tumor gene therapy

Tumor-specific gene delivery constitutes a primary challenge in nonviral mediated gene therapy. In this investigation, branched polyethylenimine (bPEI, 25 kDa) was modified by forming nanoconstructs with a natural polysaccharide, chondroitin sulfate (CS), to impart site-specific property. A library of CS-PEI (CP) nanoconstructs was fabricated by altering the content of CS and evaluated in terms of size, surface charge, morphology, pDNA loading efficiency, pDNA release assay, pDNA protection study, cytotoxicity, and transfection efficiency. In vitro transfection efficiency of CP nanoconstructs was examined in HEK293, HEK293T, HepG2, and HeLa cell lines, while their cytotoxicity was investigated in HepG2 and HeLa cells. DNase I protection assay showed that the plasmid was protected from degradation over a period of time. The CP nanoconstructs possess significantly lower toxicity and enhanced transfection efficiency compared to PEI (25 kDa) and commercial transfection reagents (i.e., superfect, fugene, and GenePORTER 2). Further, the CP nanoconstructs were also found to transfect cells in serum-containing medium. In vivo studies were carried out with pDNA loaded CP-3 nanoconstruct after intravenous (iv) injection in Ehrlich ascites tumor (EAT)-bearing mice. The outcome revealed higher concentration of CP-3 nanoconstruct in tumor mass. These findings demonstrate that CP nanoconstructs could be exploited as carriers for nanomedicine for efficient management of solid tumor.

The 'sweet' and 'bitter' involvement of glycosaminoglycans in lung diseases: pharmacotherapeutic relevance

The extracellular matrix (ECM) plays a significant role in the structure and function of the lung. The ECM is a three-dimensional fibre mesh, comprised of various interconnected and intercalated macromolecules, among which are the glycosaminoglycans (GAG). GAG are long, linear and highly charged, heterogeneous polysaccharides that are composed of a variable number of repeating disaccharide units (macromolecular sugars) and most of them, as their name implies, have a sweet taste. In the lung, GAG support the structure of the interstitium, the subepithelial tissue and the bronchial walls, and are secreted in the airway secretions. Besides maintaining lung tissue structure, GAG also play an important role in lung function as they regulate hydration and water homeostasis, modulate the inflammatory response and influence lung tissue repair and remodelling. However, depending on their size and/or degree of sulphation, and their immobilization or solubilization in the ECM, specific GAG in the lung either live up to their sweet taste/name, supporting normal lung physiology, or they are associated to 'bitter' effects, related to lung pathology. The present review discusses the biological role of GAG in the lung as well as the involvement of these molecules in various respiratory diseases. Given the great structural diversity of GAG, understanding the changes in GAG expression that occur in lung diseases may lead to novel targets for pharmacological intervention in order to prevent and/or to treat a range of lung diseases.

The use of fibrin based matrices and fibrin microbeads (FMB) for cell based tissue regeneration

BACKGROUND

Due to its good cell attachment capabilities and promotion of cell migration, fibrin serves as an interim cell-binding matrix in wounded tissues. Due to their fast degradation, unprocessed fibrin matrices have limited use in tissue engineering.

OBJECTIVE

To describe stable fibrin-based matrices for isolation, growth and delivery of stem cells for implantation to enhance tissue regeneration.

METHODS

Fibrin microbeads (FMB) were produced by moderate-heat condensation of fibrin particles in oil without compromising the cell binding capability of the fibrin.

RESULTS

Mesenchymal stem cells (MSC) were separated from different sources at much higher yields with FMB. They were further expanded on them in suspension without trypsinization and passages. Cells on FMB could be induced to differentiate into different phenotypes, such as bone and cartilage. This enabled implantation of the cells on FMB for cell-based tissue regeneration.

CONCLUSIONS

FMB technology provides a simple and effective method for cell separation, expansion in suspension and delivery for tissue regeneration.

Long-term effects for acute phase myocardial infarct VEGF165 gene transfer cardiac extracellular matrix remodeling

BACKGROUND

Cardiac remodeling is ultimately regulated by components of the extracellular matrix (ECM). We investigated the important role that growth factors play in the regulation of ECM remodeling that occurs as a consequence of myocardium damage.

METHODS AND RESULTS

Rats were submitted to the ligation of the left anterior coronary artery and pcDNA3-vascular endothelial growth factor (VEGF)(165) was immediately injected intramyocardially in the treated group. The animals were divided into large size myocardium infarction (LMI) and small size myocardium infarction, with or without gene transfer. The plasmid-containing DNA encoding VEGF(165) was injected into the cardiac muscle and its effect was observed on the ECM components. Glycosaminoglycans were identified and quantified by agarose gel based electrophoresis and ELISA as well as immunocytochemistry to examine specific cathepsin B, heparanase, and syndecan-4 changes. The amounts of hyaluronic acid (HA; p < 0.005), DS, chondroitin sulfate, and heparan sulfate (p < 0.001) were significantly increased in the LMI treated group in comparison to the other groups, which correlates with the decrease in the expression of heparanase. A decrease in the molecular mass of HA was found in the scar tissue of treated group.

CONCLUSIONS

The data obtained strongly support the idea that changes in the ECM and its components are important determinants of cardiac remodeling after myocardium infarct and may be essential for inflammatory response and attempt to stabilize the damage and provide a compensatory mechanisms to maintain cardiac output since the ECM components analyzed are involved with angiogenesis, cell proliferation and differentiation.

Involvement of highly sulfated chondroitin sulfate in the metastasis of the Lewis lung carcinoma cells

The altered expression of cell surface chondroitin sulfate (CS) and dermatan sulfate (DS) in cancer cells has been demonstrated to play a key role in malignant transformation and tumor metastasis. However, the functional highly sulfated structures in CS/DS chains and their involvement in the process have not been well documented. In the present study, a structural analysis of CS/DS from two mouse Lewis lung carcinoma (3LL)-derived cell lines with different metastatic potentials revealed a higher proportion of Delta(4,5)HexUA-GalNAc(4,6-O-disulfate) generated from E-units (GlcUA-GalNAc(4, 6-O-disulfate)) in highly metastatic LM66-H11 cells than in low metastatic P29 cells, although much less CS/DS is expressed by LM66-H11 than P29 cells. This key finding prompted us to study the role of CS-E-like structures in experimental lung metastasis. The metastasis of LM66-H11 cells to lungs was effectively inhibited by enzymatic removal of tumor cell surface CS or by preadministration of CS-E rich in E-units in a dose-dependent manner. In addition, immunocytochemical analysis showed that LM66-H11 rather than P29 cells expressed more strongly the CS-E epitope, which was specifically recognized by the phage display antibody GD3G7. More importantly, this antibody and a CS-E decasaccharide fraction, the minimal structure recognized by GD3G7, strongly inhibited the metastasis of LM66-H11 cells probably by modifying the proliferative and invading behavior of the metastatic tumor cells. These results suggest that the E-unit-containing epitopes are involved in the metastatic process and a potential target for the diagnosis and treatment of malignant tumors.

Biomolecular characterization of CD44-fibrin(ogen) binding: distinct molecular requirements mediate binding of standard and variant isoforms of CD44 to immobilized fibrin(ogen)

CD44 and fibrin(ogen) play critical roles in the hematogenous dissemination of tumor cells, including colon carcinomas. We recently reported that CD44 is the primary fibrin, but not fibrinogen, receptor on LS174T colon carcinomas. However, the biochemical nature of this interaction and the roles of CD44 standard (CD44s) versus CD44 variant (CD44v) isoforms in fibrin(ogen) recognition have yet to be delineated. Microspheres, coated with CD44 immunopurified from LS174T or T84 colon carcinoma cells, which express primarily CD44v, effectively bind to immobilized fibrin, but not fibrinogen, in shear flow. In contrast, CD44s from HL-60 cells binds to both immobilized fibrin and fibrinogen under flow. Use of highly specific enzymes and metabolic inhibitors reveals that LS174T CD44 binding to fibrin is dependent on O-glycosylation of CD44, whereas CD44s-fibrin(ogen) interaction has an absolute requirement for N-, but not O-, linked glycans. The presence of chondroitin and dermatan sulfate on CD44 standard and variant isoforms facilitates fibrin recognition. Use of the anti-CD44 function-blocking monoclonal antibody Hermes-1 nearly abolishes binding of LS174T CD44 to fibrin, although it has no effect on CD44s-fibrin(ogen) interaction. The CD44-binding site is localized within the N-terminal portion of the fibrin beta chains, including amino acid residues (beta15-66). Surface plasmon resonance experiments revealed high affinity binding of immobilized CD44 with solubilized fibrin but not fibrinogen. Collectively, these data suggest that immobilization of fibrinogen exposes a cryptic site that mediates binding to CD44s but not CD44v. Our findings may provide a rational basis for designing novel therapeutic strategies to combat metastasis.

Genetic modulation of CD44 expression by intragraft fibroblasts

This study investigated the genetic composition and the functional implication of CD44 species expressed by intragraft fibroblasts. An LEW-to-F344 heart transplant model of chronic rejection was used. Intragraft fibroblasts recovered from the chronically rejecting allografts displayed a 4.5-fold increase in expression of CD44 mRNA when compared with that of the fibroblasts isolated from non-rejecting heart allografts (P < 0.01). The intragraft fibroblasts preferentially expressed CD44 variant isoforms containing v1 exon transcript. Automated nucleotide sequence analysis revealed that the majority (90.12%) of the CD44 v1 isoforms expressed by the rejecting graft fibroblasts were encoded by a mutated CD44 mRNA, which contained two point mutations and a codon deletion in the v1 coding region. Histochemistry demonstrated a massive deposition of extracellular HA in the rejecting heart allografts. Hyaluronic acid (HA) was able to promote in vitro fibroblast adhesion, migration in a CD44-dependent manner, and survival in a serum-free culture condition. The study concludes that up-regulation of CD44 v1 isoforms expressed by the intragraft fibroblasts is associated with an increase in the deposition of extracellular HA, the principal ligand for CD44, in the allografts, suggesting that CD44-HA interaction plays an important role in regulating fibroblast recruitment and growth in allografts developing chronic rejection.

Involvement of CD44, a molecule with a thousand faces, in cancer dissemination

Tumor progression is substantially dependent on network of multiple factors, including adhesion and homing molecules, which support the malignant metastatic spread. CD44, one of the adhesion/homing molecules, has attracted much attention not only because it is expressed on many types of tumors, but also owing to its numerous functions, such as supporting cell migration and transmitting survival signals, thereby being pro-oncogenic by nature. We have used the mouse malignant LB lymphoma cell line as a model for comprehensive in vitro and in vivo analyses of the interaction between CD44 and hyaluronic acid (HA), and its relevance to tumor dissemination. The in vitro studies revealed that LB cells could not bind HA, either under static or dynamic (i.e., shear flow) conditions, unless their CD44 is activated by phorbol ester, deglycosylated (to increase the CD44 positive net charge) or transfected with CD44 variants. In parallel, in vivo experiments showed that LB cell dissemination could be controlled by injection of anti-CD44 monoclonal antibodies or hyaluronidase. Furthermore, LB cells transfected with CD44v4-v10 variant, rather than standard CD44, displayed enhanced invasion of the peripheral lymph nodes. This effect was completely lost if the HA binding site of CD44 were mutated. LB cell accumulation in the lymph nodes is caused by enhanced migration via the afferent lymphatics rather than by accelerated proliferation within the lymph node. This information can be exploited to tailor a "therapeutic suit" that should be maximally effective in inducing tumor resistance, while minimizing destructive side effects.

Hyaluronan in tissue injury and repair

A hallmark of tissue injury and repair is the turnover of extracellular matrix components. This review focuses on the role of the glycosaminoglycan hyaluronan in tissue injury and repair. Both the synthesis and degradation of extracellular matrix are critical contributors to tissue repair and remodeling. Fragmented hyaluronan accumulates during tissue injury and functions in ways distinct from the native polymer. There is accumulating evidence that hyaluronan degradation products can stimulate the expression of inflammatory genes by a variety of immune cells at the injury site. CD44 is the major cell-surface hyaluronan receptor and is required to clear hyaluronan degradation products produced during lung injury; impaired clearance of hyaluronan results in persistent inflammation. However, hyaluronan fragment stimulation of inflammatory gene expression is not dependent on CD44 in inflammatory macrophages. Instead, hyaluronan fragments utilize both Toll-like receptor (TLR) 4 and TLR2 to stimulate inflammatory genes in macrophages. Hyaluronan also is present on the cell surface of lung alveolar epithelial cells and provides protection against tissue damage by interacting with TLR2 and TLR4 on these parenchymal cells. The simple repeating structure of hyaluronan appears to be involved in a number of important aspects of noninfectious tissue injury and repair that are dependent on the size and location of the polymer as well as the interacting cells. Thus, the interactions between the endogenous matrix component hyaluronan and its signaling receptors initiate inflammatory responses, maintain structural cell integrity, and promote recovery from tissue injury.

The Involvement of CD44 and Its Novel Ligand Galectin-8 in Apoptotic Regulation of Autoimmune Inflammation

The synovial fluid (SF) cells of rheumatoid arthritis (RA) patients express a specific CD44 variant designated CD44vRA. Using a cellular model of this autoimmune disease, we show in this study that the mammalian lectin, galectin-8 (gal-8), is a novel high-affinity ligand of CD44vRA. By affinity chromatography, flow cytometry, and surface plasmon resonance, we demonstrate that gal-8 interacts with a high affinity (K(d), 6 x 10(-9) M) with CD44vRA. We further demonstrate that SF cells from RA patients express and secrete gal-8, to a concentration of 25-65 nM, well within the concentration of gal-8 required to induce apoptosis of SF cells. We further show that not all gal-8 remains freely soluble in the SF and at least part forms triple complexes with CD44 and fibrinogen that can be detected, after fibrinogen immunoprecipitation, with Abs against fibrinogen, gal-8 and CD44. These triple complexes may therefore increase the inflammatory reaction by sequestering the soluble gal-8, thereby reducing its ability to induce apoptosis in the inflammatory cells. Our findings not only shed light on the receptor-ligand relationships between CD44 and gal-8, but also underline the biological significance of these interactions, which may affect the extent of the autoimmune inflammatory response in the SF of RA patients.

Bench-to-bedside review: the role of glycosaminoglycans in respiratory disease

The extracellular matrix (ECM) plays a significant role in the mechanical behaviour of the lung parenchyma. The ECM is composed of a three-dimensional fibre mesh that is filled with various macromolecules, among which are the glycosaminoglycans (GAGs). GAGs are long, linear and highly charged heterogeneous polysaccharides that are composed of a variable number of repeating disaccharide units. There are two main types of GAGs: nonsulphated GAG (hyaluronic acid) and sulphated GAGs (heparan sulphate and heparin, chondroitin sulphate, dermatan sulphate, and keratan sulphate). With the exception of hyaluronic acid, GAGs are usually covalently attached to a protein core, forming an overall structure that is referred to as proteoglycan. In the lungs, GAGs are distributed in the interstitium, in the sub-epithelial tissue and bronchial walls, and in airway secretions. GAGs have important functions in lung ECM: they regulate hydration and water homeostasis; they maintain structure and function; they modulate the inflammatory response; and they influence tissue repair and remodelling. Given the great diversity of GAG structures and the evidence that GAGs may have a protective effect against injury in various respiratory diseases, an understanding of changes in GAG expression that occur in disease may lead to opportunities to develop innovative and selective therapies in the future.

Upregulation of chondroitin 6-sulphotransferase-1 facilitates Schwann cell migration during axonal growth

Cell migration is central to development and post-traumatic regeneration. The differential increase in 6-sulphated chondroitins during axonal growth in both crushed sciatic nerves and brain development suggests that chondroitin 6-sulphotransferase-1 (C6ST-1) is a key enzyme that mediates cell migration in the process. We have cloned the cDNA of the C6ST-1 gene (C6st1) (GenBank accession number AF178689) from crushed sciatic nerves of adult rats and produced ribonucleotide probes accordingly to track signs of 6-sulphated chondroitins at the site of injury. We found C6st1 mRNA expression in Schwann cells emigrating from explants of both sciatic nerve segments and embryonic dorsal root ganglia. Immunocytochemistry indicated pericellular 6-sulphated chondroitin products around C6ST-1-expressing frontier cells. Motility analysis of frontier cells in cultures subjected to staged treatment with chondroitinase ABC indicated that freshly produced 6-sulphated chondroitin moieties facilitated Schwann cell motility, unlike restrictions resulting from proteoglycan interaction with matrix components. Sciatic nerve crush provided further evidence of in vivo upregulation of the C6ST-1 gene in mobile Schwann cells that guided axonal regrowth 1-14 days post crush; downregulation then accompanied declining mobility of Schwann cells as they engaged in the myelination of re-growing axons. These findings are the first to identify upregulated C6st1 gene expression correlating with the motility of Schwann cells that guide growing axons through both developmental and injured environments.