Hyaluronic acid and chondroitin sulphate A rapidly promote differentiation of immature DC with upregulation of costimulatory and antigen-presenting molecules, and enhancement of NF-kappaB and protein kinase activity

Chondroitin sulfate proteoglycan 4: An attractive target for antibody-based immunotherapy

Multifunctional molecules involved in tumor progression and metastasis have been identified as valuable targets for immunotherapy. Among these, chondroitin sulfate proteoglycan 4 (CSPG4), a significant tumor cell membrane-bound proteoglycan, has emerged as a promising target, especially in light of advances in chimeric antigen receptor (CAR) T-cell therapy. The profound bioactivity of CSPG4 and its role in pivotal processes such as tumor proliferation, migration, and neoangiogenesis underline its therapeutic potential. We reviewed the molecular intricacies of CSPG4, its functional attributes within tumor cells, and the latest clinical-translational advances targeting it. Strategies such as blocking monoclonal antibodies, conjugate therapies, bispecific antibodies, small-molecule inhibitors, CAR T-cell therapies, trispecific killer engagers, and ribonucleic acid vaccines against CSPG4 were assessed. CSPG4 overexpression in diverse tumors and its correlation with adverse prognostic outcomes emphasize its significance in cancer biology. These findings suggest that targeting CSPG4 offers a promising avenue for future cancer therapy, with potential synergistic effects when combined with existing treatments.

Matrix proteoglycans in tumor inflammation and immunity

Cancer immunoediting progresses through elimination, equilibrium, and escape. Each of these phases is characterized by breaching, remodeling, and rebuilding tissue planes and structural barriers that engage extracellular matrix (ECM) components, in particular matrix proteoglycans. Some of the signals emanating from matrix proteoglycan remodeling are readily co-opted by the growing tumor to sustain an environment of tumor-promoting and immune-suppressive inflammation. Yet other matrix-derived cues can be viewed as part of a homeostatic response by the host, aiming to eliminate the tumor and restore tissue integrity. These latter signals may be harnessed for therapeutic purposes to tip the polarity of the tumor immune milieu toward anticancer immunity. In this review, we attempt to showcase the importance and complexity of matrix proteoglycan signaling in both cancer-restraining and cancer-promoting inflammation. We propose that the era of matrix diagnostics and therapeutics for cancer is fast approaching the clinic.

Biomaterial Integration in the Joint: Pathological Considerations, Immunomodulation, and the Extracellular Matrix

Defects of articular joints are becoming an increasing societal burden due to a persistent increase in obesity and aging. For some patients suffering from cartilage erosion, joint replacement is the final option to regain proper motion and limit pain. Extensive research has been undertaken to identify novel strategies enabling earlier intervention to promote regeneration and cartilage healing. With the introduction of decellularized extracellular matrix (dECM), researchers have tapped into the potential for increased tissue regeneration by designing biomaterials with inherent biochemical and immunomodulatory signals. Compared to conventional and synthetic materials, dECM-based materials invoke a reduced foreign body response. It is therefore highly beneficial to understand the interplay of how these native tissue-based materials initiate a favorable remodeling process by the immune system. Yet, such an understanding also demands increasing considerations of the pathological environment and remodeling processes, especially for materials designed for early disease intervention. This knowledge would avoid rejection and help predict complications in conditions with inflammatory components such as arthritides. This review outlines general issues facing biomaterial integration and emphasizes the importance of tissue-derived macromolecular components in regulating essential homeostatic, immunological, and pathological processes to increase biomaterial integration for patients suffering from joint degenerative diseases. This article is protected by copyright. All rights reserved.

Modification of Extracellular Matrix Enhances Oncolytic Adenovirus Immunotherapy in Glioblastoma

PURPOSE

Extracellular matrix (ECM) component hyaluronan (HA) facilitates malignant phenotypes of glioblastoma (GBM), however, whether HA impacts response to GBM immunotherapies is not known. Herein, we investigated whether degradation of HA enhances oncolytic virus immunotherapy for GBM.

EXPERIMENTAL DESIGN

Presence of HA was examined in patient and murine GBM. Hyaluronidase-expressing oncolytic adenovirus, ICOVIR17, and its parental virus, ICOVIR15, without transgene, were tested to determine if they increased animal survival and modulated the immune tumor microenvironment (TME) in orthotopic GBM. HA regulation of NF-κB signaling was examined in virus-infected murine macrophages. We combined ICOVIR17 with PD-1 checkpoint blockade and assessed efficacy and determined mechanistic contributions of tumor-infiltrating myeloid and T cells.

RESULTS

Treatment of murine orthotopic GBM with ICOVIR17 increased tumor-infiltrating CD8+ T cells and macrophages, and upregulated PD-L1 on GBM cells and macrophages, leading to prolonged animal survival, compared with control virus ICOVIR15. High molecular weight HA inhibits adenovirus-induced NF-κB signaling in macrophages in vitro, linking HA degradation to macrophage activation. Combining ICOVIR17 with anti-PD-1 antibody further extended the survival of GBM-bearing mice, achieving long-term remission in some animals. Mechanistically, CD4+ T cells, CD8+ T cells, and macrophages all contributed to the combination therapy that induced tumor-associated proinflammatory macrophages and tumor-specific T-cell cytotoxicity locally and systemically.

CONCLUSIONS

Our studies are the first to show that immune modulatory ICOVIR17 has a dual role of mediating degradation of HA within GBM ECM and subsequently modifying the immune landscape of the TME, and offers a mechanistic combination immunotherapy with PD-L1/PD-1 blockade that remodels innate and adaptive immune cells.

Pro-inflammatory roles of chondroitin sulfate proteoglycans in disorders of the central nervous system

The extracellular matrix of the central nervous system is an interconnected network of proteins and sugars. It is crucial for homeostasis, but its remodeling in neurological diseases impacts both injury and repair. Here we introduce an extracellular matrix family member that participates in immune-matrix interactions, the chondroitin sulfate proteoglycans. Chondroitin sulfate proteoglycans integrate signals from the microenvironment to activate immune cells, and they boost inflammatory responses by binding immunological receptors including toll-like receptors, selectins, CD44, and β1 integrin. Chondroitin sulfate proteoglycans also bind signaling molecules for immune cells such as cytokines and chemokines, and they activate matrix-degrading enzymes. Chondroitin sulfate proteoglycans accumulate in the damaged CNS, including during traumatic brain/spinal cord injury and multiple sclerosis, and they help drive pathogenesis. This Review aims to give new insights into the remodeling of chondroitin sulfate proteoglycans during inflammation, and how these matrix glycoproteins are able to drive neuroinflammation.

Chondroitin Sulfate Proteoglycan 4 and Its Potential As an Antibody Immunotherapy Target across Different Tumor Types

Overexpression of the chondroitin sulfate proteoglycan 4 (CSPG4) has been associated with the pathology of multiple types of such as melanoma, breast cancer, squamous cell carcinoma, mesothelioma, neuroblastoma, adult and pediatric sarcomas, and some hematological cancers. CSPG4 has been reported to exhibit a role in the growth and survival as well as in the spreading and metastasis of tumor cells. CSPG4 is overexpressed in several malignant diseases, while it is thought to have restricted and low expression in normal tissues. Thus, CSPG4 has become the target of numerous anticancer treatment approaches, including monoclonal antibody-based therapies. This study reviews key potential anti-CSPG4 antibody and immune-based therapies and examines their direct antiproliferative/metastatic and immune activating mechanisms of action.

Advances and advantages of nanomedicine in the pharmacological targeting of hyaluronan-CD44 interactions and signaling in cancer

Extensive experimental evidence in cell and animal tumor models show that hyaluronan-CD44 interactions are crucial in both malignancy and resistance to cancer therapy. Because of the intimate relationship between the hyaluronan-CD44 system and tumor cell survival and growth, it is an increasingly investigated area for applications to anticancer chemotherapeutics. Interference with the hyaluronan-CD44 interaction by targeting drugs to CD44, targeting drugs to the hyaluronan matrix, or interfering with hyaluronan matrix/tumor cell-associated CD44 interactions is a viable strategy for cancer treatment. Many of these methods can decrease tumor burden in animal models but have yet to show significant clinical utility. Recent advances in nanomedicine have offered new valuable tools for cancer detection, prevention, and treatment. The enhanced permeability and retention effect has served as key rationale for using nanoparticles to treat solid tumors. However, the targeted and uniform delivery of these particles to all regions of tumors in sufficient quantities requires optimization. An ideal nanocarrier should be equipped with selective ligands that are highly or exclusively expressed on target cells and thus endow the carriers with specific targeting capabilities. In this review, we describe how the hyaluronan-CD44 system may provide such an alternative in tumors expressing specific CD44 variants.

Hyaluronan digestion controls DC migration from the skin

The breakdown and release of hyaluronan (HA) from the extracellular matrix has been hypothesized to act as an endogenous signal of injury. To test this hypothesis, we generated mice that conditionally overexpressed human hyaluronidase 1 (HYAL1). Mice expressing HYAL1 in skin either during early development or by inducible transient expression exhibited extensive HA degradation, yet displayed no evidence of spontaneous inflammation. Further, HYAL1 expression activated migration and promoted loss of DCs from the skin. We subsequently determined that induction of HYAL1 expression prior to topical antigen application resulted in a lack of an antigenic response due to the depletion of DCs from the skin. In contrast, induction of HYAL1 expression concurrent with antigen exposure accelerated allergic sensitization. Administration of HA tetrasaccharides, before or simultaneously with antigen application, recapitulated phenotypes observed in HYAL1-expressing animals, suggesting that the generation of small HA fragments, rather than the loss of large HA molecules, promotes DC migration and subsequent modification of allergic responses. Furthermore, mice lacking TLR4 did not exhibit HA-associated phenotypes, indicating that TLR4 mediates these responses. This study provides direct evidence that HA breakdown controls the capacity of the skin to present antigen. These events may influence DC function in injury or disease and have potential to be exploited therapeutically for modification of allergic responses.

The dark side of dendritic cells: development and exploitation of tolerogenic activity that favor tumor outgrowth and immune escape

Dendritic cells (DC) play a central role in the regulation of the immune responses by providing the information needed to decide between tolerance, ignorance, or active responses. For this reason different therapies aim at manipulating DC to obtain the desired response, such as enhanced cell-mediated toxicity against tumor and infected cells or the induction of tolerance in autoimmunity and transplantation. In the last decade studies performed in these settings have started to identify (some) molecules/factors involved in the acquisition of a tolerogenic DC phenotype as well as the underlying mechanisms of their regulatory function on different immune cell populations.

Proteoglycans regulate the chemotaxis of dendritic cells derived from human peripheral blood monocytes

Dendritic cells (DCs) are a type of antigen-presenting cell which play an essential role in the immune system. The transition from immature DC (iDCs) to mature DCs (mDCs) requires appropriate maturation stimuli, such as pro-inflammatory cytokines or pathogen-derived components. Proteoglycans (PGs), which are composed of core proteins and the glycosaminoglycans that bind to them, are one of the main components of the extracellular matrix around pathogens such as bacteria. This study investigated the effects of PG extracted from the nasal septum cartilage of whale (W-PG) on the maturation of DCs derived from human peripheral blood monocytes. iDCs were prepared from human monocytes using granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). The iDCs were stimulated by W-PG alone. In another type of experiment, the iDCs were stimulated by MIX (tumor necrosis factor-alpha (TNF-alpha), IL-1beta, IL-6 and prostaglandin E(2) (PGE(2))) or a combination of MIX plus W-PG. The stimulation of W-PG alone did not induce the phenotypic maturation from iDCs. However, W-PG promoted the up-regulation of chemokine receptor CCR7-surface expression and the chemotactic responsiveness to CCR7 ligand macrophage inflammatory protein-3beta on MIX-stimulated mDCs although W-PG did not influence matrix metalloproteinase-9 activity which is an important factor in DC migration through the extracellular matrix. The findings that W-PG can selectively regulate the chemotactic activity of DCs in vitro under inflammatory conditions therefore indicate that the interaction of PGs with immune cells including DCs plays an important role in the immune response under the milieu of innate immunity.

Bioengineered hyaluronic acid elicited a nonantigenic T cell activation: implications from cosmetic medicine and surgery to nanomedicine

Hyaluronan is known to act as a filling material of extracellular matrices and as an adhesive substrate for cellular migration. Consequently, it is widely used in aesthetic medicine and surgery, and it would be expected to be used in nanomedicine. Previous clinical case reports associated hyaluronic acid implants to delayed immune-mediated adverse effects. A series of experiments to evaluate immune cell activation supported by this dermal filler and nanomedical biomaterial were performed. The study comprised a total of 12 individuals. Four healthy individuals, none with cosmetically injected dermal filler, were considered as control. Five individuals carried injections of hyaluronic acid dermal filler. Three individuals carried injections of hyaluronic acid dermal filler and presented delayed adverse effects related to the dermal filler. Hyaluronic acid-stimulated peripheral blood mononuclear cells (PBMC) produced low levels of pro-inflammatory cytokines. Phytohemagglutinine (PHA)-stimulated PBMC from patients with hyaluronic implants presenting adverse effects showed a slight increase in the production of interferon (IFN)-gamma and higher expression of CD25, CD69, or CD71. In conclusion, hyaluronic acid administration elicited a laboratory evidence of immune cell activation. Production of low levels of proinflammatory cytokines in vitro could be an observation for low-grade inflammation in vivo resulting in T cell activation.

Effects of proteoglycan extracted from nasal cartilage of salmon heads on maturation of dendritic cells derived from human peripheral blood monocytes

Dendritic cells (DCs) play an essential role in the immune system. The transition from immature DC (iDCs) to mature DCs (mDCs) requires appropriate stimuli such as pro-inflammatory cytokines. Proteoglycans (PGs) are one of the main components of extracellular matrix, and some types of PGs are known to induce maturation of murine DCs. Recent studies have investigated the potential benefits of PG from nasal cartilage of salmon head (S-PG). This study investigated the effects of S-PG on maturation of human monocyte-derived DCs. iDCs were prepared from human monocytes using the appropriate cytokines and then stimulated by S-PG alone. In another experiment, iDCs were stimulated by a combination of pro-inflammatory cytokines (MIX) plus S-PG. Although the stimulation of S-PG alone did not induce phenotypic maturation from iDCs, CD40 expression on DCs stimulated by S-PG alone was lower than that of iDCs. In contrast, the phenotypic and functional characteristics of DCs stimulated by MIX+S-PG were similar to those of DCs stimulated by MIX alone. As a result, S-PG did not demonstrate a significant effect with regard to maturation of human monocyte-derived DCs.

From secretome analysis to immunology: chitosan induces major alterations in the activation of dendritic cells via a TLR4-dependent mechanism

Dendritic cells are known to be activated by a wide range of microbial products, leading to cytokine production and increased levels of membrane markers such as major histocompatibility complex class II molecules. Such activated dendritic cells possess the capacity to activate naïve T cells. In the present study we demonstrated that immature dendritic cells secrete both the YM1 lectin and lipocalin-2. By testing the ligands of these two proteins, chitosan and siderophores, respectively, we also demonstrated that chitosan, a degradation product of various fungal and protozoal cell walls, induces an activation of dendritic cells at the membrane level, as shown by the up-regulation of membrane proteins such as class II molecules, CD80 and CD86 via a TLR4-dependent mechanism, but is not able to induce cytokine production. This led to the production of activated dendritic cells unable to stimulate T cells. However, costimulation with other microbial products overcame this partial activation and restored the capacity of these activated dendritic cells to stimulate T cells. In addition, successive stimulation with chitosan and then by lipopolysaccharide induced a dose-dependent change in the cytokinic IL-12/IL-10 balance produced by the dendritic cells.

Chondroitin sulphate: a complex molecule with potential impacts on a wide range of biological systems

Chondroitin sulphate (CS) is widely consumed orally by humans, and non-humans as it is believed to be beneficial for those with joint-related pathologies. Data concerning the functions of chondroitin sulphate in this, and other, biological systems are being actively extended. However, it is important to appreciate that chondroitin sulphate molecules represent a heterogeneous population the structure of which varies with source. As commercially available chondroitin sulphate is derived from a range of sources, and the molecular functions of chondroitin sulphate depend upon the structure, there are a range of structures available with differing potential for therapeutic impacts on a range of pathologies. While the safety of CS is not presently in doubt, poor quality finished products have the potential to compromise clinical and lab-based studies and will fail to give consumers all of the benefits available. Major parameters including bioavailability and uptake have been studied but it is clear that significant challenges remain in the identification of composition, sequence and size impacts on function, understanding how the consumed material is altered during uptake and travels to a site of action and how it exerts an influence on biological processes. If we understand these factors it may be possible to predict impacts upon biological processes and identify specific chondroitin sulphate structures which may target specific pathologies.

Innate immunity, macrophage activation, and atherosclerosis

Inflammation underpins the development of atherosclerosis. Initiation and progression of vascular inflammation involves a complex cellular network, with macrophages as major contributors. Activated macrophages produce proinflammatory mediators, bridge innate and adaptive immunity, regulate lipid retention, and participate directly in vascular repair and remodeling. Recent efforts to elucidate molecular mechanisms involved in the regulation of vascular inflammation in atherosclerosis have implicated several families of innate immune recognition receptors in inflammatory activation during the course of this disease. This article reviews our current understanding of innate immune recognition receptors, signaling pathways, and putative ligands implicated in activation of macrophages in the disease. In its final section, we propose a model for the role of macrophages in bridging inflammation and atherosclerosis from the perspective of innate immune recognition and activation.

Differential effects of agarose and poly(lactic-co-glycolic acid) on dendritic cell maturation

Application of biomaterials in combination products in which the biomaterial is presented to the host with a biological component prompts the need for understanding the biomaterial-associated adjuvant effect in the immune response against antigens associated with such a product. We have previously demonstrated that a polymer commonly used in tissue engineering and vaccine delivery, poly(lactic-co-glycolic acid) (PLGA), exerts an adjuvant effect in vivo, which was supported by PLGA-induced dendritic cell (DC) maturation in vitro. In this study, the effects of agarose and PLGA on DC maturation were compared in vitro to establish differential biomaterial effects. Human monocyte-derived DCs were treated with agarose or PLGA microparticles or films, and their maturation effect was measured as expression of costimulatory and MHC class II molecules, allostimulatory capacity, and proinflammatory cytokine secretion. Direct comparison of DC maturation phenotype indicated that PLGA was a stronger stimulus of DC maturation than agarose, and this maturation was not affected by microparticle phagocytosis. However, agarose-treated DCs showed higher activation of nuclear factor kappaB (NFkappaB) 24 h after the initial stimulation of DCs. Taken together, these results demonstrate differential biomaterial effects on DC maturation, substantiating the maturation effect of PLGA, and provide screening methods for biomaterial adjuvant effect for applications in combination products.

Hyaluronan fragments act as an endogenous danger signal by engaging TLR2

Upon tissue injury, high m.w. hyaluronan (HA), a ubiquitously distributed extracellular matrix component, is broken down into lower m.w. (LMW) fragments, which in turn activate an innate immune response. In doing so, LMW HA acts as an endogenous danger signal alerting the immune system of a breach in tissue integrity. In this report, we demonstrate that LMW HA activates the innate immune response via TLR-2 in a MyD88-, IL-1R-associated kinase-, TNFR-associated factor-6-, protein kinase Czeta-, and NF-kappaB-dependent pathway. Furthermore, we show that intact high m.w. HA can inhibit TLR-2 signaling. Finally, we demonstrate that LMW HA can act as an adjuvant promoting Ag-specific T cell responses in vivo in wild-type but not TLR-2(null) mice.

Monocyte chemoattractant protein-1 (MCP-1) inhibits the intestinal-like differentiation of monocytes

Monocytes (MO) migrating into normal, non-inflamed intestinal mucosa undergo a specific differentiation resulting in a non-reactive, tolerogenic intestinal macrophage (IMAC). Recently we demonstrated the differentiation of MO into an intestinal-like macrophage (MAC) phenotype in vitro in a three-dimensional cell culture model (multi-cellular spheroid or MCS model). In the mucosa of patients with inflammatory bowel disease (IBD) in addition to normal IMAC, a reactive MAC population as well as increased levels of monocyte chemoattractant protein 1 (MCP-1) is found. The aim of this study was to investigate the influence of MCP-1 on the differentiation of MO into IMAC. MCS were generated from adenovirally transfected HT-29 cells overexpressing MCP-1, macrophage inflammatory protein 3 alpha (MIP-3alpha) or non-transfected controls and co-cultured with freshly elutriated blood MO. After 7 days of co-culture MCS were harvested, and expression of the surface antigens CD33 and CD14 as well as the intracellular MAC marker CD68 was determined by flow-cytometry or immunohistochemistry. MCP-1 and MIP-3alpha expression by HT-29 cells in the MCS was increased by transfection at the time of MCS formation. In contrast to MIP-3alpha, MCP-1 overexpression induced a massive migration of MO into the three-dimensional aggregates. Differentiation of IMAC was disturbed in MCP-1-transfected MCS compared to experiments with non-transfected control aggregates, or the MIP-3alpha-transfected MCS, as indicated by high CD14 expression of MO/IMAC cultured inside the MCP-1-transfected MCS, as shown by immunohistochemistry and FACS analysis. Neutralization of MCP-1 was followed by an almost complete absence of monocyte migration into the MCS. MCP-1 induced migration of MO into three-dimensional spheroids generated from HT-29 cells and inhibited intestinal-like differentiation of blood MO into IMAC. It may be speculated that MCP-1 could play a role in the disturbed IMAC differentiation in IBD mucosa.

CD44 and TGFbeta1 synergise to induce expression of a functional NADPH oxidase in promyelocytic cells

Bone marrow stromal cells produce large amounts of extracellular matrix and cytokines. Amongst them, hyaluronan, a glycosaminoglycan and ligand for the cell surface molecule CD44, and TGFbeta1, a cytokine particularly important in monocyte differentiation. We have studied in vitro the role of hyaluronan and TGFbeta1 in the differentiation process of U937 monocytic progenitor cells. We provide evidence that, in the presence of whole blood-derived serum, the addition of hyaluronan is sufficient to induce the expression of NADPH-oxidase components but not of other monocytic markers (CD14, CD11b, and VLA-4). In the presence of plasma-derived serum, besides hyaluronan, the additional presence of TGFbeta1 was required for the expression of all of the components of the NADPH oxidase. We further show that hyaluronan mediates its effect through CD44. We conclude that cell matrix factors act cooperatively with cytokines to induce the expression of the components of the NADPH-oxidase in monocytic progenitor cells.

Differential levels of dendritic cell maturation on different biomaterials used in combination products

Immature dendritic cells (iDCs) were derived from human peripheral blood monocytes, and treated with films of biomaterials commonly used in combination products (e.g., tissue engineered constructs or vaccines) to assess the resultant dendritic cell (DC) maturation compared to positive control of lipopolysaccharide (LPS) treatment for DC maturation or negative control of untreated iDCs. The following biomaterials were tested: alginate, agarose, chitosan, hyaluronic acid, 75:25 poly(lactic-co-glycolic acid) (PLGA). The effect of DC culture on these films was undertaken to identify biomaterials which support DC maturation and those biomaterials that did not. Dendritic cells treated with chitosan or PLGA (agarose to a lesser extent) films increased expression levels of CD86, CD40, and HLA-DQ, compared to control iDCs, similar to LPS-matured DCs, whereas DCs treated with alginate or hyaluronic acid films decreased their expression levels of these same molecules. In summary, a differential effect of the biomaterial on which iDCs were cultured was observed as far as the extent of induced DC maturation. The effect of biomaterials on DC maturation, and the associated adjuvant effect, is a novel biocompatibility selection and design criteria for biomaterials to be used in combination products in which immune consequences are potential complications or outcomes.

Differential activation profiles of multiple transcription factors during dendritic cell maturation

Immature dendritic cells (DC) at the environmental interfaces, such as the skin, constantly survey the tissue for the emergence of microbial products and pro-inflammatory mediators. Upon recognition of such "danger" signals, they undergo dynamic reprogramming of gene expression and functions, the process known as DC maturation, which plays critical roles in both innate and adaptive immune responses. Although DC have been shown to discriminate different maturation stimuli by expressing stimulus-specific signature genes and unique phenotypic and functional properties, underlying mechanisms for this extraordinary plasticity remain relatively unclear. We hypothesized that DC might activate unique sets of transcription factors (TF) upon sensing different stimuli. To test this hypothesis, we transduced a mouse epidermal-derived DC line XS106 to express the luciferase reporter gene under the control of each of 15 different cis-enhancer elements. The resulting DC panels were then exposed to 14 different microbial, endogenous, environmental, and pharmacological agents that produced unique maturational changes. This approach allowed systematic determination of TF activation profiles in DC. Our results revealed striking diversity, with different classes of stimuli triggering preferential activation of distinct sets of TF. We propose that differential TF usage represents a previously unrecognized mechanism regulating the direction of DC maturation.

Hyaluronic acid or TNF-alpha plus fibronectin triggers granulocyte macrophage-colony-stimulating factor mRNA stabilization in eosinophils yet engages differential intracellular pathways and mRNA binding proteins

Eosinophils (Eos) accumulate in airways and lung parenchyma of active asthmatics. GM-CSF is a potent inhibitor of Eos apoptosis both in vitro and in vivo and is produced by activated fibroblasts, mast cells, T lymphocytes as well as Eos. Cytokine release by Eos is preceded by GM-CSF mRNA stabilization induced by TNF-alpha plus fibronectin. Hyaluronic acid (HA) is a major extracellular matrix proteoglycan, which also accumulates in the lung during asthma exacerbations. In this study we have analyzed the effects of HA on Eos survival and GM-CSF expression. We demonstrate that like TNF-alpha plus fibronectin, HA stabilizes GM-CSF mRNA, increases GM-CSF secretion, and prolongs in vitro Eos survival. GM-CSF mRNA stabilization accounts for most of the observed GM-CSF mRNA accumulation and protein production. Unlike TNF-alpha plus fibronectin, GM-CSF mRNA stabilization induction by HA requires continuous extracellular signal-regulated kinase phosphorylation. Finally, to identify potential protein regulators responsible for GM-CSF mRNA stabilization, immunoprecipitation-RT-PCR studies revealed increased GM-CSF mRNA associated with YB-1, HuR, and heterogeneous nuclear ribonucleoprotein (hnRNP) C after TNF-alpha plus fibronectin but only hnRNP C after HA. Thus, our data suggest that both TNF-alpha plus fibronectin and HA, which are relevant physiological effectors in asthma, contributes to long-term Eos survival in vivo by enhancing GM-CSF production through two different posttranscriptional regulatory pathways involving extracellular signal-regulated kinase phosphorylation and RNA binding proteins YB-1, HuR, and hnRNP C.

Pathophysiological mechanisms in osteoarthritis lead to novel therapeutic strategies

Osteoarthritis (OA) is a debilitating, progressive disease of diarthrodial joints associated with aging. At the molecular level, OA is characterized by an imbalance between anabolic (i.e. extracellular matrix biosynthesis) and catabolic (i.e. extracellular matrix degradation) pathways in which articular cartilage is the principal site of tissue injury responses. The pathophysiology of OA also involves the synovium in that 'nonclassical' inflammatory synovial processes contribute to OA progression. Chondrocytes are critical to the OA process in that the progression of OA can be judged by the vitality of chondrocytes and their ability to resist apoptosis. Growth factors exemplified by insulin-like growth factor-1, its binding proteins and transforming growth factor-beta contribute to anabolic pathways including compensatory biosynthesis of extracellular matrix proteins. Catabolic pathways are altered by cytokine genes such as interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) which are upregulated in OA. In addition, IL-1 and TNF-alpha downregulate extracellular matrix protein biosynthesis while concomitantly upregulating matrix metalloproteinase (MMP) gene expression. When MMPs are activated, cartilage extracellular matrix degradation ensues apparently because levels of endogenous cartilage MMP inhibitors cannot regulate MMP activity. Therapeutic strategies designed to modulate the imbalance between anabolic and catabolic pathways in OA may include neutralizing cytokine activity or MMP gene expression or inhibiting signaling pathways which result in apoptosis dependent on mature caspase activity or mitogen-activated protein kinase (MAPK) activity. MAPK activity appears critical for regulating chondrocyte and synoviocyte apoptosis and MMP genes.

Endoplasmic reticulum stress induces hyaluronan deposition and leukocyte adhesion

There is mounting evidence that perturbations in endoplasmic reticulum (ER) function play a key role in the pathogenesis of a broad range of diseases. We have examined the ability of ER stress to modulate leukocyte binding to colonic and aortic smooth muscle cells. In vitro, control smooth muscle cells bind few leukocytes, but treatment with compounds that induce ER stress, including tunicamycin, A23187, and thapsigargin, promotes leukocyte binding. Likewise, dextran sulfate, another agent capable of inducing ER stress and promoting inflammation in vivo, strongly induces leukocyte adhesion. The bound leukocytes are released by hyaluronidase treatment, indicating a critical role for hyaluronan-containing structures in mediating leukocyte binding. Affinity histochemistry demonstrated that hyaluronan accumulates and is present in cable-like structures in the treated, but not the untreated, cultures and that these structures serve as attachment sites for leukocytes. Hyaluronan-rich regions of both murine and human inflamed colon contain numerous cells that stain intensely for ER-resident chaperones containing the KDEL sequence, demonstrating a relationship between ER stress and hyaluronan deposition in vivo. These results indicate that ER stress may contribute to chronic inflammation by forming a hyaluronan-rich extracellular matrix that is conducive to leukocyte binding.