Hyaluronan fragments synergize with interferon-gamma to induce the C-X-C chemokines mig and interferon-inducible protein-10 in mouse macrophages

Bioactivated scaffolds promote angiogenesis and lymphangiogenesis for dermal regeneration in vivo

Chronic wounds represent an unresolved medical challenge with significant impact for patients' quality of life and global healthcare. Diverse in origin, ischemic-hypoxic and inflammatory conditions play central roles as pathological features that impede proper tissue regeneration. In this study, we propose an innovative approach to address this challenge. Our novel strategy utilizes photosynthetic biomaterials to restore the wound healing process firstly by promoting a normoxic, regeneration-supporting environment and secondly by mitigating inflammation through restoring lymphatic fluid transport and improving blood perfusion. We designed bioartificial scaffolds with photosynthetic cyanobacteria (Synechococcus sp. PCC 7002) and assessed their functional integration in a bilateral full-thickness skin defect on the backs of mice over a period of 7 days. Illuminated photosynthetic cyanobacteria facilitated local tissue oxygenation independent of blood perfusion. Additionally, genetic modification enabled the secretion of lymphangiogenic hyaluronic acid (HA) into the wound area. After 7 days, the scaffolds were explanted and histologically examined, assessing cell migration (HE staining) and protein expression (CD31, LYVE-1, VEGFR3, Ly6G, and F4/80). Results demonstrated successful colonization of bioartificial scaffolds with cyanobacteria. Following implantation into bilateral full-thickness skin defects, we observed an adherent vascularized basal layer beneath the bioactivated scaffolds after 7 days. Substantial increases in cell migration within bacteria-loaden scaffolds were noted, accompanied by a heightened expression of lymphatic (LYVE-1 and VEGFR3) and endothelial cell markers (CD31). Simultaneously, an augmented expression of acute (Ly6G) and late (F4/80) inflammatory proteins was observed. In summary, we developed a viable photosynthetic scaffold by integrating cyanobacteria into dermal regeneration materials (DRM), promoting the expression of lymphatic, endothelial, and inflammatory proteins under hypoxic conditions. The findings from this study represent a significant advancement in establishing autotrophic tissue engineering approaches, advocating for the use of photosynthetic cells in treating a broad spectrum of hypoxic conditions.

Self-assembled hyaluronic acid nanoparticles for the topical treatment of inflammatory skin diseases: Beyond drug carriers

Inflammatory skin diseases represent a significant health concern, affecting approximately 20-25% of the global population. These conditions not only reduce an individual's quality of life but also impose a huge burden on both humanity and society. However, addressing these challenges is hindered by their chronic nature, insufficient therapeutic effectiveness, and the propensity for recurrence and adverse side effects. Hyaluronic acid (HA) has emerged as a potential solution to these barriers, owing to its excellent attributes such as biocompatibility, non-toxicity, and targeted drug delivery. However, its practical application has been limited because endogenous hyaluronidase (HYAL) rapidly degrades HA in inflamed skin thus reducing its ability to penetrate deep into the skin. Interestingly, recent research has expanded the role of self-assembled HA-nanoparticles (HA-NPs) beyond drug carriers; they are resistant to HYAL, thereby enabling deep skin penetration, and possess inherent anti-inflammatory properties. Moreover, these abilities can be fine-tuned depending on the conditions during particle synthesis. Additionally, their role as a drug delivery system holds potential for use as a multi-target drug or hybrid drug. In conclusion, this review aims to specifically introduce and highlight the emerging potential of HA-NPs as a topical treatment for inflammatory skin conditions.

Endothelial cell activation and glycocalyx shedding - potential as biomarkers in patients with lupus nephritis

Lupus nephritis (LN) is a common and severe manifestation of systemic lupus erythematosus and an important cause of acute and chronic kidney injury. Early diagnosis of LN and preventing relapses are key to preserving renal reserve. However, due to the complexity and heterogeneity of the disease, clinical management remains challenging. Kidney biopsy remains the gold standard for confirming the diagnosis of LN and subsequent assessment of kidney histopathology, but it is invasive and cannot be repeated frequently. Current clinical indicators of kidney function such as proteinuria and serum creatinine level are non-specific and do not accurately reflect histopathological changes, while anti-dsDNA antibody and C3 levels reflect immunological status but not kidney injury. Identification of novel and specific biomarkers for LN is prerequisite to improve management. Renal function deterioration is associated with changes in the endothelial glycocalyx, a delicate gel-like layer located at the interface between the endothelium and bloodstream. Inflammation induces endothelial cell activation and shedding of glycocalyx constituents into the circulation. This review discusses the potential role of soluble glycocalyx components as biomarkers of active LN, especially in patients in whom conventional serological and biochemical markers do not appear helpful.

Hyaluronan regulates sperm-induced inflammatory response by enhancing sperm attachment to bovine endometrial epithelial cells via CD44: in-silico and in-vitro approaches

Recently, we reported that sperm induce cluster of differentiation 44 (CD44) expression and Toll-like receptor 2 (TLR2)-mediated inflammatory response in bovine uterus. In the present study, we hypothesized that the interaction between CD44 of bovine endometrial epithelial cells (BEECs) and hyaluronan (HA) affects sperm attachment and thereby enhancing TLR2-mediated inflammation. To test our hypothesis, at first, in-silico approaches were employed to define the binding affinity of HA for CD44 and TLR2. Further, an in-vitro experiment using the sperm-BEECs co-culture model was applied to investigate the effect of HA on sperm attachment and inflammatory response. Here, low molecular weight (LMW) HA at different concentrations (0, 0.1, 1, or 10 µg/mL) was incubated with BEECs for 2 h followed by the co-culture without- or with non-capacitated washed sperm (10⁶/ml) for additional 3 h was performed. The present in-silico model clarified that CD44 is a high-affinity receptor for HA. Moreover, TLR2 interactions with HA oligomer (4- and 8-mers) target a different subdomain (h-bonds) compared to TLR2-agonist (PAM3) which targets a central hydrophobic pocket. However, the interaction of LMW HA (32-mers) with TLR2 revealed no stability of HA at any pocket of TLR2. Notably, the immunofluorescence analysis revealed the HA localization in both endometrial stroma and epithelia of ex-vivo endometrial explant. Moreover, ELISA showed significant levels of HA in BEECs culture media. Importantly, BEECs pretreatment with HA prior to sperm exposure increased the number of attached sperm to BEECs, and upregulated the transcriptional levels of pro-inflammatory genes (TNFA, IL-1B, IL-8, and PGES) in BEECs in response to sperm. However, BEECs treated with HA only (no sperm exposure) did not show any significant effect on the transcript abundance of pro-inflammatory genes when compared to the non-treated BEECs. Altogether, our findings strongly suggest a possible cross-talk between sperm and endometrial epithelial cells via HA and HA binding receptors (CD44 and TLR2) to induce a pro-inflammatory response in bovine uterus.

The Study of the Extracellular Matrix in Chronic Inflammation: A Way to Prevent Cancer Initiation?

Bidirectional communication between cells and their microenvironment has a key function in normal tissue homeostasis, and in disease initiation, progression and a patient's prognosis, at the very least. The extracellular matrix (ECM), as an element of all tissues and cellular microenvironment, is a frequently overlooked component implicated in the pathogenesis and progression of several diseases. In the inflammatory microenvironment (IME), different alterations resulting from remodeling processes can affect ECM, progressively inducing cancer initiation and the passage toward a tumor microenvironment (TME). Indeed, it has been demonstrated that altered ECM components interact with a variety of surface receptors triggering intracellular signaling that affect cellular pathways in turn. This review aims to support the notion that the ECM and its alterations actively participate in the promotion of chronic inflammation and cancer initiation. In conclusion, some data obtained in cancer research with the employment of decellularized ECM (dECM) models are described. The reported results encourage the application of dECM models to investigate the short circuits contributing to the creation of distinct IME, thus representing a potential tool to avoid the progression toward a malignant lesion.

Proteoglycans in Toll-like receptor responses and innate immunity

The extracellular matrix (ECM) is an active and dynamic feature of tissues that not only provides gross structure but also plays key roles in cellular responses. The ever-changing microenvironment responds dynamically to cellular and external signals, and in turn influences cell fate, tissue development, and response to environmental injury or microbial invasion. It is therefore paramount to understand how the ECM components interact with each other, the environment and cells, and how they mediate their effects. Among the ECM components that have recently garnered increased attention, proteoglycans (PGs) deserve special note. Recent evidence strongly suggests that they play a crucial role both in health maintenance and disease development. In particular, proteoglycans dictate whether homeostasis or cell death will result from a given injury, by triggering and modulating activation of the innate immune system, via a conserved array of receptors that recognize exogenous (infectious) or endogenous (tissue damage) molecular patterns. Innate immune activation by proteoglycans has important implications for the understanding of cell-matrix interactions in health and disease. In this review, we will summarize the current state of knowledge of innate immune signaling by proteoglycans, discuss the implications, and explore future directions to define progress in this area of extracellular matrix biology.

Methods for isolating and analyzing physiological hyaluronan: a review

The carbohydrate hyaluronan (or hyaluronic acid, HA) is found in all human tissues and biofluids where it has wide-ranging functions in health and disease that are dictated by both its abundance and size. Consequently, hyaluronan evaluation in physiological samples has significant translational potential. Although the analytical tools and techniques for probing other biomolecules such as proteins and nucleic acids have become standard approaches in biochemistry, those available for investigating hyaluronan are less well established. In this review, we survey methods related to the assessment of native hyaluronan in biological specimens, including protocols for separating it from biological matrices and technologies for determining its concentration and molecular weight.

Can Heart Valve Decellularization Be Standardized? A Review of the Parameters Used for the Quality Control of Decellularization Processes

When a tissue or an organ is considered, the attention inevitably falls on the complex and delicate mechanisms regulating the correct interaction of billions of cells that populate it. However, the most critical component for the functionality of specific tissue or organ is not the cell, but the cell-secreted three-dimensional structure known as the extracellular matrix (ECM). Without the presence of an adequate ECM, there would be no optimal support and stimuli for the cellular component to replicate, communicate and interact properly, thus compromising cell dynamics and behaviour and contributing to the loss of tissue-specific cellular phenotype and functions. The limitations of the current bioprosthetic implantable medical devices have led researchers to explore tissue engineering constructs, predominantly using animal tissues as a potentially unlimited source of materials. The high homology of the protein sequences that compose the mammalian ECM, can be exploited to convert a soft animal tissue into a human autologous functional and long-lasting prosthesis ensuring the viability of the cells and maintaining the proper biomechanical function. Decellularization has been shown to be a highly promising technique to generate tissue-specific ECM-derived products for multiple applications, although it might comprise very complex processes that involve the simultaneous use of chemical, biochemical, physical and enzymatic protocols. Several different approaches have been reported in the literature for the treatment of bone, cartilage, adipose, dermal, neural and cardiovascular tissues, as well as skeletal muscle, tendons and gastrointestinal tract matrices. However, most of these reports refer to experimental data. This paper reviews the most common and latest decellularization approaches that have been adopted in cardiovascular tissue engineering. The efficacy of cells removal was specifically reviewed and discussed, together with the parameters that could be used as quality control markers for the evaluation of the effectiveness of decellularization and tissue biocompatibility. The purpose was to provide a panel of parameters that can be shared and taken into consideration by the scientific community to achieve more efficient, comparable, and reliable experimental research results and a faster technology transfer to the market.

Synergistic and receptor-mediated targeting of arthritic joints via intra-articular injectable smart hydrogels containing leflunomide-loaded lipid nanocarriers

Intra-articular drug delivery represents a tempting strategy for local treatment of rheumatoid arthritis. Targeting drugs to inflamed joints bypasses systemic-related side effects. Albeit, rapid drug clearance and short joint residence limit intra-articular administration. Herein, injectable smart hydrogels comprising free/nanoencapsulated leflunomide (LEF) were developed. Nanostructured lipid carriers (NLCs), 200-300 nm, were coated with either chondroitin sulfate (CHS), hyaluronic acid (HA), or chitosan (CS) to provide joint targetability. Coated NLCs were incorporated in either hyaluronic/pluronic (HP) or chitosan/β-glycerophosphate (CS/βGP) hydrogels. Optimized systems ensured convenient gelation time (14-100 s), injectability (5-15 s), formulation-dependent mechanical strength, and extended LEF release up to 51 days. In vivo intra-articular injection in induced arthritis rat model revealed that rats treated with HA-coated NLCs showed the fastest recovery. Histopathological examination demonstrated perfect joint healing in case of HA-coated LEF-NLCs in CS/βGP thermogel manifested as minor erosion of subchondral bone, improved intensity of extracellular matrix, cartilage thickness, and chondrocyte number. Both HA- and CHS-coated NLCs reduced TNF-α level 4-5-fold relative to positive control. The feat would be achieved via active targeting to CD44 receptors overexpressed in the articular tissue, limiting chondrocyte apoptosis together with innate synergistic targetability by promoting chondrocyte proliferation and neovascularization, inhibiting the production of pro-inflammatory cytokines, thus enhancing cartilaginous tissue repair.

Modulation of hyaluronan signaling as a therapeutic target in human disease

The extracellular matrix is an active participant, modulator and mediator of the cell, tissue, organ and organismal response to injury. Recent research has highlighted the role of hyaluronan, an abundant glycosaminoglycan constituent of the extracellular matrix, in many fundamental biological processes underpinning homeostasis and disease development. From this basis, emerging studies have demonstrated the therapeutic potential of strategies which target hyaluronan synthesis, biology and signaling, with significant promise as therapeutics for a variety of inflammatory and immune diseases. This review summarizes the state of the art in this field and discusses challenges and opportunities in what could emerge as a new class of therapeutic agents, that we term "matrix biologics".

Dynamic role of LMW-hyaluronan fragments and Toll-like receptors 2,4 in progression of bleomycin induced lung parenchymal injury to fibrosis

Background

Pulmonary fibrosis (PF) is a progressive and lethal lung disease of elderly whose incidence has been increasing following the Covid-19 pandemic caused by severe acute respiratory syndrome corona virus 2 (SARS-CoV-2). PF immunopathogenesis involves progressive alveolar epithelial cell damage, release of damage-associated molecular patterns (DAMPs), and extracellular matrix (ECM) injury. We assessed the dynamic role of LMW-hyaluronan (LMW-HA) as DAMP in initiation of host immune TLR-2,4 responses and as determinant in progression of ECM injury to fibrosis. Male Wistar rats were divided into Group I (saline control, n = 24) and Group II (intratracheal bleomycin, 7 U/kg/animal, n = 24). Animals were euthanized on 0, 7, 14, and 28 days. The time course of release of LMW-HA, TLR-2,4 mRNA and protein levels, and NF-κB-p65 levels after bleomycin injury were correlated with the development of parenchymal inflammation, remodelling, and fibrosis.

Results

Acute lung injury caused by bleomycin significantly increases the pro-inflammatory LMW-HA levels and elevates TLR-2,4 levels on day 7. Subsequently, TLR-2 upregulation, TLR-4 downregulation, and NF-κB signalling follow on days 14 and 28. This results in progressive tissue inflammation, alveolar and interstitial macrophage accumulation, and fibrosis.

Conclusions

LMW-HA significantly increases in PF caused by non-infectious and infectious (Covid-19) etiologies. The accumulating HA fragments function as endogenous DAMPs and trigger inflammatory responses, through differential TLR2 and TLR4 signalling, thus promoting inflammation and macrophage influx. LMW-HA are reflective of the state of ongoing tissue inflammation and may be considered as a natural biosensor for fibrotic lung diseases and as potential therapeutic targets.

Immunomodulatory Role of the Extracellular Matrix Within the Liver Disease Microenvironment

Chronic liver disease when accompanied by underlying fibrosis, is characterized by an accumulation of extracellular matrix (ECM) proteins and chronic inflammation. Although traditionally considered as a passive and largely architectural structure, the ECM is now being recognized as a source of potent damage-associated molecular pattern (DAMP)s with immune-active peptides and domains. In parallel, the ECM anchors a range of cytokines, chemokines and growth factors, all of which are capable of modulating immune responses. A growing body of evidence shows that ECM proteins themselves are capable of modulating immunity either directly via ligation with immune cell receptors including integrins and TLRs, or indirectly through release of immunoactive molecules such as cytokines which are stored within the ECM structure. Notably, ECM deposition and remodeling during injury and fibrosis can result in release or formation of ECM-DAMPs within the tissue, which can promote local inflammatory immune response and chemotactic immune cell recruitment and inflammation. It is well described that the ECM and immune response are interlinked and mutually participate in driving fibrosis, although their precise interactions in the context of chronic liver disease are poorly understood. This review aims to describe the known pro-/anti-inflammatory and fibrogenic properties of ECM proteins and DAMPs, with particular reference to the immunomodulatory properties of the ECM in the context of chronic liver disease. Finally, we discuss the importance of developing novel biotechnological platforms based on decellularized ECM-scaffolds, which provide opportunities to directly explore liver ECM-immune cell interactions in greater detail.

Low Molecular Weight Hyaluronan Induces an Inflammatory Response in Ovarian Stromal Cells and Impairs Gamete Development In Vitro

The ovarian stroma, the microenvironment in which female gametes grow and mature, becomes inflamed and fibrotic with age. Hyaluronan is a major component of the ovarian extracellular matrix (ECM), and in other aging tissues, accumulation of low molecular weight (LMW) hyaluronan fragments can drive inflammation. Thus, we hypothesized that LMW hyaluronan fragments contribute to female reproductive aging by stimulating an inflammatory response in the ovarian stroma and impairing gamete quality. To test this hypothesis, isolated mouse ovarian stromal cells or secondary stage ovarian follicles were treated with physiologically relevant (10 or 100 μg/mL) concentrations of 200 kDa LMW hyaluronan. In ovarian stromal cells, acute LMW hyaluronan exposure, at both doses, resulted in the secretion of a predominantly type 2 (Th2) inflammatory cytokine profile as revealed by a cytokine antibody array of conditioned media. Additional qPCR analyses of ovarian stromal cells demonstrated a notable up-regulation of the eotaxin receptor Ccr3 and activation of genes involved in eosinophil recruitment through the IL5-CCR3 signaling pathway. These findings were consistent with an age-dependent increase in ovarian stromal expression of Ccl11, a major CCR3 ligand. When ovarian follicles were cultured in 10 or 100 μg/mL LMW hyaluronan for 12 days, gametes with compromised morphology and impaired meiotic competence were produced. In the 100 μg/mL condition, LMW hyaluronan induced premature meiotic resumption, ultimately leading to in vitro aging of the resulting eggs. Further, follicles cultured in this LMW hyaluronan concentration produced significantly less estradiol, suggesting compromised granulosa cell function. Taken together, these data demonstrate that bioactive LMW hyaluronan fragments may contribute to reproductive aging by driving an inflammatory stromal milieu, potentially through eosinophils, and by directly compromising gamete quality through impaired granulosa cell function.

Macrophages promote a profibrotic phenotype in orbital fibroblasts through increased hyaluronic acid production and cell contractility

Graves’ orbitopathy (GO) is an autoimmune inflammatory disease affecting the orbit. Orbital fibroblasts are a key component in GO pathogenesis, which includes inflammation, adipogenesis, hyaluronic acid (HA) secretion, and fibrosis. Macrophages are thought to participate in the immunological stage of GO, but whether they can directly affect the fibroblasts phenotype and modulate disease progression is unknown. We previously showed that GO adipogenic and fibrotic phenotypes could be modelled in a pseudo-physiological 3D environment in vitro. Here, we introduced macrophages in this 3D culture model to investigate role for macrophages in modulating adipogenesis, HA production, and contractility in orbital fibroblasts. Macrophages had a minimal effect on lipid droplet formation in fibroblasts, but significantly increased HA production and cell contractility, suggesting that they may promote the fibrotic phenotype. This effect was found to be mediated at least in part through phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) activation and linked to an increase in actin polymerization and protrusive activity in fibroblasts. Overall our work shows for the first time a direct role for macrophages in modulating the fibroblasts’ phenotype in GO, supporting a role for macrophages in the progression of the fibrotic phenotype through induction of HA production and stimulation of the contractile phenotype in orbital fibroblasts.

Hyaluronan in immune dysregulation and autoimmune diseases

The tissue microenvironment contributes to local immunity and to the pathogenesis of autoimmune diseases - a diverse set of conditions characterized by sterile inflammation, immunity against self-antigens, and destruction of tissues. However, the specific factors within the tissue microenvironment that contribute to local immune dysregulation in autoimmunity are poorly understood. One particular tissue component implicated in multiple autoimmune diseases is hyaluronan (HA), an extracellular matrix (ECM) polymer. HA is abundant in settings of chronic inflammation and contributes to lymphocyte activation, polarization, and migration. Here, we first describe what is known about the size, amount, and distribution of HA at sites of autoimmunity and in associated lymphoid structures in type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. Next, we examine the recent literature on HA and its impact on adaptive immunity, particularly in regards to the biology of lymphocytes and Foxp3+ regulatory T-cells (Treg), a T-cell subset that maintains immune tolerance in healthy individuals. We propose that HA accumulation at sites of chronic inflammation creates a permissive environment for autoimmunity, characterized by CD44-mediated inhibition of Treg expansion. Finally, we address potential tools and strategies for targeting HA and its receptor CD44 in chronic inflammation and autoimmunity.

Intermolecular G-Quadruplex Induces Hyaluronic Acid-DNA Superpolymers Causing Cancer Cell Swelling, Blebbing, and Death

Over the past decade, nanomedicine has gained considerable attraction through its relevance, for example, in "smart" delivery, thus creating platforms for novel treatments. Here, we report a natural polymer-DNA conjugate that undergoes self-assembly in a K⁺-dependent fashion to form a G-quadruplex (GQ) and generate superpolymeric structures. We derivatized a thiolated conjugate of the naturally occurring glycosaminoglycan polymer hyaluronic acid (HASH) with short G-rich DNA (HASH-DNA) that can form an intermolecular noncanonical GQ structure. Gel mobility shift assay and circular dichroism measurements confirmed HASH conjugation to DNA and K⁺-dependent GQ formation, respectively. Transmission electron microscopy and scanning electron microscopy results indicated that the addition of K⁺ to the HASH-DNA conjugate led to the formation of micron-range structures, whereas control samples remained unordered and as a nebulous globular form. Confocal microscopy of a fluorescently labeled form of the superpolymer verified increased cellular uptake. The HASH-DNA conjugates showed toxicity in HeLa cells, whereas a scrambled DNA (Mut) conjugate HASH-Mut showed no cytotoxicity, presumably because of nonformation of the superpolymeric structure. To understand the mechanism of cell death and if the superpolymeric structure is responsible for it, we monitored the cell size and observed an average of 23% increase in size compared to 4.5% in control cells at 4.5 h. We believe that cellular stress is generated presumably by the intracellular assembly of this large superpolymeric nanostructure causing cell blebbing with no exit option. This approach provides a new strategy of cellular delivery of a targeted naturally occurring polymer and a novel way to induce superpolymeric structure formation that acts as a therapeutic.

Fragmented hyaluronan has no alarmin function assessed in arthritis synovial fibroblast and chondrocyte cultures

Hyaluronan (HA) is a large polymer and an important component of the extracellular matrix. During homeostasis, high molecular mass HA is the predominant form, but upon inflammation, degradation products of HA accumulate. These HA fragments (HA-fs) have been reported to possess pro-inflammatory activities and thus act as alarmins, notifying immune cells of danger via TLR4 and CD44. HA is found in large quantities in synovial joint fluid. In order to reveal a potential role of HA-fs in arthritis pathogenesis, the in vitro effects of HA of various molecular masses (from 1680 kDa to oligosaccharide HA) on synovial fibroblasts and chondrocytes from rheumatoid arthritis patients, and on peripheral blood mononuclear cells from healthy donors, were investigated. TLR4 and CD44 surface expression was confirmed by immunocytochemistry, and cell activation was determined based on cytokine and chemokine production. While the cell types investigated expressed TLR4 and CD44, no increased release of IL-1ß, IL-6, IL-8, IL-10, IL-12 or TNF-α was detected after HA stimulation. Similarly, HA did not enhance activation after priming cells with low doses of LPS or by forming complexes with LPS. Hence, this study does not support the common view of HA-fs being pro-inflammatory mediators and it is not likely that HA-fs generated during arthritis contribute to disease pathogenesis.

Different approaches to heart valve decellularization: A comprehensive overview of the past 30 years

Xenogeneic decellularized heart valve scaffolds have the potential to overcome the limitations of existing bioprosthetic heart valves that have limited duration due to calcification and tissue degeneration phenomena. This article presents a review of 30 years of decellularization approaches adopted in cardiovascular tissue engineering, with a focus on the use, either individually or in combination, of different detergents. The safety and efficacy of cell-removal procedures are specifically reported and discussed, as well as the structure and biomechanics of the treated extracellular matrix (ECM). Detergent residues within the ECM, production of hyaluronan fragments, safe removal of cellular debris, and the persistence of the alpha-Gal epitope after the decellularization treatments are of particular interest as parameters for the identification of the best tissue for the manufacture of bioprostheses. Special attention has also been given to key factors that should be considered in the manufacture of the next generation of xenogeneic bioprostheses, where tissues must retain the ability to be remodeled and to grow in weight along with body reshaping.

Genetic basis for hyper production of hyaluronic acid in natural and engineered microorganisms

Hyaluronic acid, or HA, is a rigid and linear biopolymer belonging to the class of the glycosaminoglycans, and composed of repeating units of the monosaccharides glucuronic acid and N-acetylglucosamine. HA has multiple important functions in the human body, due to its properties such as bio-compatibility, lubricity and hydrophilicity, it is widely applied in the biomedical, food, health and cosmetic fields. The growing interest in this molecule has motivated the discovery of new ways of obtaining it. Traditionally, HA has been extracted from rooster comb-like animal tissues. However, due to legislation laws HA is now being produced by bacterial fermentation using Streptococcus zooepidemicus, a natural producer of HA, despite it being a pathogenic microorganism. With the expansion of new genetic engineering technologies, the use of organisms that are non-natural producers of HA has also made it possible to obtain such a polymer. Most of the published reviews have focused on HA formulation and its effects on different body tissues, whereas very few of them describe the microbial basis of HA production. Therefore, for the first time this review has compiled the molecular and genetic bases for natural HA production in microorganisms together with the main strategies employed for heterologous production of HA.

Catch bond interaction allows cells to attach to strongly hydrated interfaces

Hyaluronans are a class of glycosaminoglycans that are widespread in the mammalian body and serve a variety of functions. Their most striking characteristic is their pronounced hydrophilicity and their capability to inhibit unspecific adhesion when present at interfaces. Catch-bond interactions are used by the CD44 receptor to interact with this inert material and to roll on the surfaces coated with hyaluronans. In this minireview, the authors discuss the general properties of hyaluronans and the occurrence and relevance of the CD44 catch-bond interaction in the context of hematopoiesis, cancer development, and leukemia.

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.

Characterization of the Antiglioma Effect of the Oncolytic Adenovirus VCN-01

Despite the recent advances in the development of antitumor therapies, the prognosis for patients with malignant gliomas remains dismal. Therapy with tumor-selective viruses is emerging as a treatment option for this devastating disease. In this study we characterize the anti-glioma effect of VCN-01, an improved hyaluronidase-armed pRB-pathway-selective oncolytic adenovirus that has proven safe and effective in the treatment of several solid tumors. VCN-01 displayed a significant cytotoxic effect on glioma cells in vitro. In vivo, in two different orthotopic glioma models, a single intra-tumoral administration of VCN-01 increased overall survival significantly and led to long-term survivors free of disease.

The role of hyaluronan in the pathobiology and treatment of respiratory disease

Hyaluronan, a ubiquitous naturally occurring glycosaminoglycan, is a major component of the extracellular matrix, where it participates in biological processes that include water homeostasis, cell-matrix signaling, tissue healing, inflammation, angiogenesis, and cell proliferation and migration. There are emerging data that hyaluronan and its degradation products have an important role in the pathobiology of the respiratory tract. We review the role of hyaluronan in respiratory diseases and present evidence from published literature and from clinical practice supporting hyaluronan as a novel treatment for respiratory diseases. Preliminary data show that aerosolized exogenous hyaluronan has beneficial activity against airway inflammation, protects against bronchial hyperreactivity and remodeling, and disrupts the biofilm associated with chronic infection. This suggests a role in airway diseases with a predominant inflammatory component such as rhinosinusitis, asthma, chronic obstructive pulmonary disease, cystic fibrosis, and primary ciliary dyskinesia. The potential for hyaluronan to complement conventional therapy will become clearer when data are available from controlled trials in larger patient populations.

Host and pathogen hyaluronan signal through human siglec-9 to suppress neutrophil activation

Inhibitory CD33-related Siglec receptors regulate immune cell activation upon engaging ubiquitous sialic acids (Sias) on host cell surface glycans. Through molecular mimicry, Sia-expressing pathogen group B Streptococcus binds inhibitory human Siglec-9 (hSiglec-9) to blunt neutrophil activation and promote bacterial survival. We unexpectedly discovered that hSiglec-9 also specifically binds high molecular weight hyaluronan (HMW-HA), another ubiquitous host glycan, through a region of its terminal Ig-like V-set domain distinct from the Sia-binding site. HMW-HA recognition by hSiglec-9 limited neutrophil extracellular trap (NET) formation, oxidative burst, and apoptosis, defining HMW-HA as a regulator of neutrophil activation. However, the pathogen group A Streptococcus (GAS) expresses a HMW-HA capsule that engages hSiglec-9, blocking NET formation and oxidative burst, thereby promoting bacterial survival. Thus, a single inhibitory lectin receptor detects two distinct glycan "self-associated molecular patterns" to maintain neutrophil homeostasis, and two leading human bacterial pathogens have independently evolved molecular mimicry to exploit this immunoregulatory mechanism.

KEY MESSAGE

HMW-HA is the first example of a non-sialic acid containing glycan to be recognized by CD33-related Siglecs. HMW-HA engagement of hSiglec-9 attenuates neutrophil activation. Group A Streptococcus exploits hSiglec-9 recognition via its polysaccharide HMW-HA capsule to subvert neutrophil killing.

High Sensitivity Method to Estimate Distribution of Hyaluronan Molecular Sizes in Small Biological Samples Using Gas-Phase Electrophoretic Mobility Molecular Analysis

Hyaluronan is a negatively charged polydisperse polysaccharide where both its size and tissue concentration play an important role in many physiological and pathological processes. The various functions of hyaluronan depend on its molecular size. Up to now, it has been difficult to study the role of hyaluronan in diseases with pathological changes in the extracellular matrix where availability is low or tissue samples are small. Difficulty to obtain large enough biopsies from human diseased tissue or tissue from animal models has also restricted the study of hyaluronan. In this paper, we demonstrate that gas-phase electrophoretic molecular mobility analyzer (GEMMA) can be used to estimate the distribution of hyaluronan molecular sizes in biological samples with a limited amount of hyaluronan. The low detection level of the GEMMA method allows for estimation of hyaluronan molecular sizes from different parts of small organs. Hence, the GEMMA method opens opportunity to attain a profile over the distribution of hyaluronan molecular sizes and estimate changes caused by disease or experimental conditions that has not been possible to obtain before.

Size Matters: Molecular Weight Specificity of Hyaluronan Effects in Cell Biology

Hyaluronan signaling properties are unique among other biologically active molecules, that they are apparently not influenced by postsynthetic molecular modification, but by hyaluronan fragment size. This review summarizes the current knowledge about the generation of hyaluronan fragments of different size and size-dependent differences in hyaluronan signaling as well as their downstream biological effects.

Mycosis fungoides with epidermal mucinosis: a variant of mycosis fungoides with a spongiosis-like pattern

BACKGROUND

The histopathologic diagnosis of mycosis fungoides (MF) has classically relied on the presence of atypical epidermotropic T-lymphocytes predominating over spongiosis. However, in some cases of MF, prominent epidermal mucinosis in a spongiosis-like pattern mimics a spongiotic dermatitis. To our knowledge, only one series in the literature has thus far recognized the presence of epidermal mucinosis in MF.

METHODS

We evaluated 30 skin biopsies from 18 patients with the clinical diagnosis of MF, which fulfilled all histopathologic criteria for patch- or plaque-stage MF, but also showed epidermal mucinosis in a spongiosis-like pattern. A total of 15 specimens were studied by immunohistochemistry, and seven were tested for T-cell receptor (TCR) gene rearrangements. Twenty biopsies of spongiotic dermatitides were included as controls.

RESULTS

We confirmed the presence of epidermal mucinosis in all 30 cases of MF with a spongiosis-like pattern based on histopathologic criteria and the colloidal iron stain for mucin. Immunohistochemistry in 15 specimens showed significant loss of pan-T-cell antigens CD5 (10/15) and CD7 (14/15); and TCR clonality was detected in 7 specimens from 6 patients, supporting the diagnosis of MF.

CONCLUSIONS

We report helpful histopathologic criteria for distinguishing MF with epidermal mucinosis in a spongiosis-like pattern from spongiotic dermatitis.

Interactions between Hyaluronan and Its Receptors (CD44, RHAMM) Regulate the Activities of Inflammation and Cancer

The glycosaminoglycan hyaluronan (HA), a major component of extracellular matrices, and cell surface receptors of HA have been proposed to have pivotal roles in cell proliferation, migration, and invasion, which are necessary for inflammation and cancer progression. CD44 and receptor for HA-mediated motility (RHAMM) are the two main HA-receptors whose biological functions in human and murine inflammations and tumor cells have been investigated comprehensively. HA was initially considered to be only an inert component of connective tissues, but is now known as a “dynamic” molecule with a constant turnover in many tissues through rapid metabolism that involves HA molecules of various sizes: high molecular weight HA (HMW HA), low molecular weight HA, and oligosaccharides. The intracellular signaling pathways initiated by HA interactions with CD44 and RHAMM that lead to inflammatory and tumorigenic responses are complex. Interestingly, these molecules have dual functions in inflammations and tumorigenesis. For example, the presence of CD44 is involved in initiation of arthritis, while the absence of CD44 by genetic deletion in an arthritis mouse model increases rather than decreases disease severity. Similar dual functions of CD44 exist in initiation and progression of cancer. RHAMM overexpression is most commonly linked to cancer progression, whereas loss of RHAMM is associated with malignant peripheral nerve sheath tumor growth. HA may similarly perform dual functions. An abundance of HMW HA can promote malignant cell proliferation and development of cancer, whereas antagonists to HA-CD44 signaling inhibit tumor cell growth in vitro and in vivo by interfering with HMW HA-CD44 interaction. This review describes the roles of HA interactions with CD44 and RHAMM in inflammatory responses and tumor development/progression, and how therapeutic strategies that block these key inflammatory/tumorigenic processes may be developed in rodent and human diseases.

The Hyaluronic Acid-HDAC3-miRNA Network in Allergic Inflammation

We previously reported the anti-allergic effect of high molecular weight form of hyaluronic acid (HMW-HA). In doing so, HA targets CD44 and inhibits FcεRI signaling and cross-talk between epidermal growth factor receptor (EGFR) and FcεRI. We previously reported the role of histone deacetylases (HDACs) in allergic inflammation and allergic inflammation-promoted enhanced tumorigenic potential. We reported regulatory role of HA in the expression of HDAC3. In this review, we will discuss molecular mechanisms associated with anti-allergic effect of HA in relation with HDACs. The role of microRNAs (miRNAs) in allergic inflammation has been reported. We will also discuss the role of miRNAs in allergic inflammation in relation with HA-mediated anti-allergic effects.

Inter-α inhibitor protein and its associated glycosaminoglycans protect against histone-induced injury

Extracellular histones are mediators of tissue injury and organ dysfunction; therefore they constitute potential therapeutic targets in sepsis, inflammation, and thrombosis. Histone cytotoxicity in vitro decreases in the presence of plasma. Here, we demonstrate that plasma inter-α inhibitor protein (IAIP) neutralizes the cytotoxic effects of histones and decreases histone-induced platelet aggregation. These effects are mediated through the negatively charged glycosaminoglycans (GAGs) chondroitin sulfate and high-molecular-weight hyaluronan (HMW-HA) associated with IAIP. Cell surface anionic glycosaminoglycans heparan sulfate and HA protect the cells against histone-mediated damage in vitro. Surface plasmon resonance showed that both IAIP and HMW-HA directly bind to recombinant histone H4. In vivo neutralization of histones with IAIP and HMW-HA prevented histone-induced thrombocytopenia, bleeding, and lung microvascular thrombosis, decreased neutrophil activation, and averted histone-induced production of inflammatory cytokines and chemokines. IAIP and HMW-HA colocalized with histones in necrotic tissues and areas that displayed neutrophil extracellular traps. Increasing amounts of IAIP-histone complexes detected in the plasma of septic baboons correlated with increase in histones and/or nucleosomes and consumption of plasma IAIP. Our data suggest that IAIP, chondroitin sulfate, and HMW-HA are potential therapeutic agents to protect against histone-induced cytotoxicity, coagulopathy, systemic inflammation, and organ damage during inflammatory conditions such as sepsis and trauma.

Inhibitory effects of the ethyl acetate extract from bulbs of Scilla scilloides on lipoxygenase and hyaluronidase activities

CONTEXT

Scilla scilloides Druce (Liliaceae) is a folk medicine to treat dermal inflammation; however, the medicinal properties of this plant have not been completely established.

OBJECTIVE

The current study investigates the potent anti-inflammatory effects of S. scilloides bulbs for its traditional usage using lipoxygenase and hyaluronidase as the inflammation model. To gain insight into the active constituents, nine homoisoflavones (1-9) were subsequently tested.

MATERIALS AND METHODS

Lipoxygenase and hyaluronidase inhibition of ethyl acetate extract from the bulbs of this plant within 2000 µg/mL or homoisoflavones within 1000 µM were determined by colorimetric methods. RAW264.7 cells were incubated with 10 or 50 µM homoisoflavones plus lipopolysaccharide (LPS) for 24 h. The culture media were collected and analyzed for determination of the nitric oxide (NO) level by the colorimetric Griess method to measure the extent of inflammation.

RESULTS

The extract exhibited inhibitory effects on lipoxygenase and hyaluronidase activities with IC50 values 31.5 and 169 µg/mL, respectively. Among the nine homoisoflavones tested, four (1 and 3-5) resulted in 79.3-97.9% higher lipoxygenase inhibition than 6.7-32.7% of the others at 500 µM. Calculated IC50 values indicated 5 as the compound responsible for strong lipoxygenase inhibition with 15.8 µM as the IC50 value. In the hyaluronidase assay, all homoisoflavones tested at 1000 µM demonstrated 16.2-58.0% inhibition. Incubating the cells in the presence of all nine homoisoflavones tested at 50 µM significantly suppressed the NO production, downward to 1.5-66.0%, in the LPS-activated macrophage cells as a model.

DISCUSSION AND CONCLUSION

These results may indicate a potential role of S. scilloides for anti-inflammatory purposes.

Divergent Temporal Expression of Hyaluronan Metabolizing Enzymes and Receptors with Craniotomy vs. Controlled-Cortical Impact Injury in Rat Brain: A Pilot Study

Traumatic brain injury (TBI) triggers many secondary changes in tissue biology, which ultimately determine the extent of injury and clinical outcome. Hyaluronan [hyaluronic acid (HA)] is a protective cementing gel present in the intercellular spaces whose degradation has been reported as a causative factor in tissue damage. Yet little is known about the expression and activities of genes involved in HA catabolism after TBI. Young adult male Sprague-Dawley rats were assigned to three groups: naïve control, craniotomy, and controlled-cortical impact-induced TBI (CCI-TBI). Four animals per group were sacrificed at 4 h, 1, 3, and 7 days post-CCI. The mRNA expression of hyaluronan synthases (HAS1-3), hyaluronidases (enzymes for HA degradation, HYAL 1–4, and PH20), and CD44 and RHAMM (membrane receptors for HA signaling and removal) were determined using real-time PCR. Compared to the naïve controls, expression of HAS1 and HAS2 mRNA, but not HAS3 mRNA increased significantly following craniotomy alone and following CCI with differential kinetics. Expression of HAS2 mRNA increased significantly in the ipsilateral brain at 1 and 3 days post-CCI. HYAL1 mRNA expression also increased significantly in the craniotomy group and in the contralateral CCI at 1 and 3 days post-CCI. CD44 mRNA expression increased significantly in the ipsilateral CCI at 4 h, 1, 3, and 7 days post-CCI (up to 25-fold increase). These data suggest a dynamic regulation and role for HA metabolism in secondary responses to TBI.

Synergistic up-regulation of CXCL10 by virus and IFN γ in human airway epithelial cells

Airway epithelial cells are the first line of defense against viral infections and are instrumental in coordinating the inflammatory response. In this study, we demonstrate the synergistic stimulation of CXCL10 mRNA and protein, a key chemokine responsible for the early immune response to viral infection, following treatment of airway epithelial cells with IFN γ and influenza virus. The synergism also occurred when the cells were treated with IFN γ and a viral replication mimicker (dsRNA) both in vitro and in vivo. Despite the requirement of type I interferon (IFNAR) signaling in dsRNA-induced CXCL10, the synergism was independent of the IFNAR pathway since it wasn't affected by the addition of a neutralizing IFNAR antibody or the complete lack of IFNAR expression. Furthermore, the same synergistic effect was also observed when a CXCL10 promoter reporter was examined. Although the responsive promoter region contains both ISRE and NFκB sites, western blot analysis indicated that the combined treatment of IFN γ and dsRNA significantly augmented NFκB but not STAT1 activation as compared to the single treatment. Therefore, we conclude that IFN γ and dsRNA act in concert to potentiate CXCL10 expression in airway epithelial cells via an NFκB-dependent but IFNAR-STAT independent pathway and it is at least partly regulated at the transcriptional level.

Recombinant human hyaluronidase PH20 does not stimulate an acute inflammatory response and inhibits lipopolysaccharide-induced neutrophil recruitment in the air pouch model of inflammation

Hyaluronidase (Hyal) and low m.w. hyaluronan (LMW HA) fragments have been widely reported to stimulate the innate immune response. However, most hyaluronidases used were purified from animal tissues (e.g., bovine testis Hyal [BTH]), and contain endotoxin and other unrelated proteins. We tested a highly purified recombinant human Hyal (rHuPH20) and endotoxin-free HA fragments from M(r) 5,000 to 1,500,000 in the rodent air pouch model of inflammation to determine their potential for stimulation of the innate immune response. Exogenous LMW HA fragments (average M(r) 200,000) failed to induce either cytokine/chemokine production or neutrophil infiltration into the air pouch. Challenging the air pouch with LPS or BTH stimulated production of cytokines and chemokines but rHuPH20 did not, suggesting that neither PH20 nor generation of LMW HA fragments in situ stimulates cytokine and chemokine production. LPS and BTH also induced neutrophil infiltration into the air pouch, which was not observed with rHuPH20 treatment. Endotoxin-depleted BTH had much reduced proinflammatory activity, suggesting that the difference in inflammatory responses between rHuPH20 and BTH is likely due to endotoxin contaminants in BTH. When rHuPH20 was dosed with LPS, the induction of cytokines and chemokines was the same as LPS alone, but neutrophil infiltration was inhibited, likely by interrupting HA-CD44 interaction. Our results indicate that neither rHuPH20 nor its directly generated HA catabolites have inflammatory properties in the air pouch model, and rHuPH20 can instead inhibit some aspects of inflammation, such as neutrophil infiltration into the air pouch.

Tumor targeting profiling of hyaluronan-coated lipid based-nanoparticles

Hyaluronan (HA), a naturally occurring high Mw (HMw) glycosaminoglycan, has been shown to play crucial roles in cell growth, embryonic development, healing processes, inflammation, and tumor development and progression. Low Mw (LMw, <10 kDa) HA has been reported to provoke inflammatory responses, such as induction of cytokines, chemokines, reactive nitrogen species and growth factors. Herein, we prepared and characterized two types of HA coated (LMw and HMw) lipid-based targeted and stabilized nanoparticles (tsNPs) and tested their binding to tumor cells expressing the HA receptor (CD44), systemic immunotoxicity, and biodistribution in tumor bearing mice. In vitro, the Mw of the surface anchored HA had a significant influence on the affinity towards CD44 on B16F10 murine melanoma cells. LMw HA-tsNPs exhibited weak binding, while binding of tsNPs coated with HMw HA was characterized by high binding. Both types of tsNPs had no measured effect on cytokine induction in vivo following intravenous administration to healthy C57BL/6 mice suggesting no immune activation. HMw HA-tsNPs showed enhanced circulation time and tumor targeting specificity, mainly by accumulating in the tumor and its vicinity compared with LMw HA-tsNPs. Finally, we show that methotrexate (MTX), a drug commonly used in cancer chemotherapy, entrapped in HMw HA-tsNPs slowly diffused from the particles with a half-life of 13.75 days, and improved the therapeutic outcome in a murine B16F10 melanoma model compared with NPs suggesting an active cellular targeting beyond the Enhanced Permeability and Retention (EPR) effect. Taken together, these findings have major implications for the use of high molecular weight HA in nanomedicine as a selective and safe active cellular targeting moiety.

Hyaluronan, a crucial regulator of inflammation

Hyaluronan (HA), a major component of the extracellular matrix (ECM), plays a key role in regulating inflammation. Inflammation is associated with accumulation and turnover of HA polymers by multiple cell types. Increasingly through the years, HA has become recognized as an active participant in inflammatory, angiogenic, fibrotic, and cancer promoting processes. HA and its binding proteins regulate the expression of inflammatory genes, the recruitment of inflammatory cells, the release of inflammatory cytokines, and can attenuate the course of inflammation, providing protection against tissue damage. A growing body of evidence suggests the cell responses are HA molecular weight dependent. HA fragments generated by multiple mechanisms throughout the course of inflammatory pathologies, elicit cellular responses distinct from intact HA. This review focuses on the role of HA in the promotion and resolution of inflammation.

Low molecular weight hyaluronan activates cytosolic phospholipase A2α and eicosanoid production in monocytes and macrophages

Hyaluronan (HA) is the major glycosaminoglycan in the extracellular matrix. During inflammation, there is an increased breakdown of HA, resulting in the accumulation of low molecular weight (LMW) HA and activation of monocytes and macrophages. Eicosanoids, derived from the cytosolic phospholipase A2 group IVA (cPLA2α) activation, are potent lipid mediators also attributed to acute and chronic inflammation. The aim of this study was to determine the effect of LMW HA on cPLA2α activation, arachidonic acid (AA) release, and subsequent eicosanoid production and to examine the receptors and downstream mechanisms involved in these processes in monocytes and differently polarized macrophages. LMW HA was a potent stimulant of AA release in a time- and dose-dependent manner, induced cPLA2α, ERK1/2, p38, and JNK phosphorylation, as well as activated COX2 expression and prostaglandin (PG) E2 production in primary human monocytes, murine RAW 264.7, and wild-type bone marrow-derived macrophages. Specific cPLA2α inhibitor blocked HA-induced AA release and PGE2 production in all of these cells. Using CD44, TLR4, TLR2, MYD88, RHAMM or STAB2 siRNA-transfected macrophages and monocytes, we found that AA release, cPLA2α, ERK1/2, p38, and JNK phosphorylation, COX2 expression, and PGE2 production were activated by LMW HA through a TLR4/MYD88 pathway. Likewise, PGE2 production and COX2 expression were blocked in Tlr4(-/-) and Myd88(-/-) mice, but not in Cd44(-/-) mice, after LMW HA stimulation. Moreover, we demonstrated that LMW HA activated the M1 macrophage phenotype with the unique cPLA2α/COX2(high) and COX1/ALOX15/ALOX5/LTA4H(low) gene and PGE2/PGD2/15-HETE(high) and LXA4(low) eicosanoid profile. These findings reveal a novel link between HA-mediated inflammation and lipid metabolism.

The roles of hyaluronan/RHAMM/CD44 and their respective interactions along the insidious pathways of fibrosarcoma progression

Fibrosarcomas are rare malignant mesenchymal tumors originating from fibroblasts. Importantly, fibrosarcoma cells were shown to have a high content and turnover of extracellular matrix (ECM) components including hyaluronan (HA), proteoglycans, collagens, fibronectin, and laminin. ECMs are complicated structures that surround and support cells within tissues. During cancer progression, significant changes can be observed in the structural and mechanical properties of the ECM components. Importantly, hyaluronan deposition is usually higher in malignant tumors as compared to benign tissues, predicting tumor progression in some tumor types. Furthermore, activated stromal cells are able to produce tissue structure rich in hyaluronan in order to promote tumor growth. Key biological roles of HA result from its interactions with its specific CD44 and RHAMM (receptor for HA-mediated motility) cell-surface receptors. HA-receptor downstream signaling pathways regulate in turn cellular processes implicated in tumorigenesis. Growth factors, including PDGF-BB, TGFβ2, and FGF-2, enhanced hyaluronan deposition to ECM and modulated HA-receptor expression in fibrosarcoma cells. Indeed, FGF-2 through upregulation of specific HAS isoforms and hyaluronan synthesis regulated secretion and net hyaluronan deposition to the fibrosarcoma pericellular matrix modulating these cells' migration capability. In this paper we discuss the involvement of hyaluronan/RHAMM/CD44 mediated signaling in the insidious pathways of fibrosarcoma progression.

Anti-inflammatory and antioxidative effects of a methanol extract from bulbs of Scilla scilloides

The extract from bulbs of Scilla scilloides exhibited inhibitory effects in lipoxygenase and hyaluronidase assays and various oxidation models in vitro. Incubating the cells in the presence of this extract ameliorated t-butyl hydroperoxide-induced cytotoxicity from 27% to 57% in a macrophage model. The results may indicate the potential role of S. scilloides for its anti-inflammatory and antioxidative effects.

The Role of Hyaluronan and CD44 in the Pathogenesis of Lupus Nephritis

Systemic lupus erythematosus (SLE) is a prototype autoimmune disease that affects multiorgan systems. Lupus nephritis is one of the most severe manifestations of SLE whereby immune-mediated inflammation can lead to permanent damage within the glomerular, tubulo-interstitial, and vascular compartments of the kidney, resulting in acute or chronic renal failure. The mechanisms that regulate host inflammatory responses and tissue injury are incompletely understood. Accumulating evidence suggests that hyaluronan and its interaction with its cell surface receptor CD44 plays an important role in mediating pathogenic mechanisms in SLE. This paper discusses the putative mechanisms through which hyaluronan and CD44 contribute to the pathogenesis of SLE, with particular emphasis on lupus nephritis.

Hyaluronic acid: A key molecule in skin aging

SKIN AGING IS A MULTIFACTORIAL PROCESS CONSISTING OF TWO DISTINCT AND INDEPENDENT MECHANISMS: intrinsic and extrinsic aging. Youthful skin retains its turgor, resilience and pliability, among others, due to its high content of water. Daily external injury, in addition to the normal process of aging, causes loss of moisture. The key molecule involved in skin moisture is hyaluronic acid (HA) that has unique capacity in retaining water. There are multiple sites for the control of HA synthesis, deposition, cell and protein association and degradation, reflecting the complexity of HA metabolism. The enzymes that synthesize or catabolize HA and HA receptors responsible for many of the functions of HA are all multigene families with distinct patterns of tissue expression. Understanding the metabolism of HA in the different layers of the skin and the interactions of HA with other skin components will facilitate the ability to modulate skin moisture in a rational manner.

Mechanistic overview of reactive species-induced degradation of the endothelial glycocalyx during hepatic ischemia/reperfusion injury

Endothelial cells are covered by a delicate meshwork of glycoproteins known as the glycocalyx. Under normophysiological conditions the glycocalyx plays an active role in maintaining vascular homeostasis by deterring primary and secondary hemostasis and leukocyte adhesion and by regulating vascular permeability and tone. During (micro)vascular oxidative and nitrosative stress, which prevails in numerous metabolic (diabetes), vascular (atherosclerosis, hypertension), and surgical (ischemia/reperfusion injury, trauma) disease states, the glycocalyx is oxidatively and nitrosatively modified and degraded, which culminates in an exacerbation of the underlying pathology. Consequently, glycocalyx degradation due to oxidative/nitrosative stress has far-reaching clinical implications. In this review the molecular mechanisms of reactive oxygen and nitrogen species-induced destruction of the endothelial glycocalyx are addressed in the context of hepatic ischemia/reperfusion injury as a model disease state. Specifically, the review focuses on (i) the mechanisms of glycocalyx degradation during hepatic ischemia/reperfusion, (ii) the molecular and cellular players involved in the degradation process, and (iii) its implications for hepatic pathophysiology. These topics are projected against a background of liver anatomy, glycocalyx function and structure, and the biology/biochemistry and the sources/targets of reactive oxygen and nitrogen species. The majority of the glycocalyx-related mechanisms elucidated for hepatic ischemia/reperfusion are extrapolatable to the other aforementioned disease states.

Hyaluronan tetrasaccharide in the cerebrospinal fluid is associated with self-repair of rats after chronic spinal cord compression

The objective of this study was to explore changes in hyaluronan levels in the cerebrospinal fluid (CSF) in a spinal cord compression model, to investigate whether hyaluronan tetrasaccharide was involved in this process, and to test the effects of hyaluronan tetrasaccharide on neuron and oligodendrocyte repair. We developed a chronic spinal cord compression model with various sizes of polymer sheets (1.5×0.7×0.3 mm(3); 5×1.5×0.7 mm(3)) that were implanted microsurgically underneath the C(5-6) laminae. The rats were divided into three groups: a sham group, a mildly compressed (MC) group, and a widely compressed (WC) group. Locomotor functional evaluations revealed that the behavioral function of the MC and WC groups dropped to their lowest level from the fourth to fifth week and gradually recovered thereafter. The hyaluronan levels in the CSF gradually increased after spinal cord compression. Furthermore, hyaluronan tetrasaccharide was involved in the hyaluronan change. In addition, we found that nuclear factor kappa B (NF-κB) and cellular inhibitor-of-apoptosis protein 2 (c-IAP(2)) were co-expressed in neurons and oligodendrocytes, and caspase-3 expression gradually decreased in the compression model. The brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) expression was upregulated in astrocytes at the fourth week post-compression. Hyaluronan tetrasaccharide (HA(4)) induced NF-κB and c-IAP(2) to suppress the H(2)O(2)-induced apoptosis in primary neuronal cultures and increased BDNF and VEGF expression in astrocytic cultures in vitro. These findings suggest that HA(4) in the CSF may associate with behavioral recovery by increasing the levels of NF-κB, c-IAP(2), and neurotrophic factors after chronic spinal cord compression.

Hyaluronic acid as a rescue therapy for trinitrobenzene sulfonic acid-induced colitis through Cox-2 and PGE2 in a Toll-like receptor 4-dependent way

We hypothesized whether systemic administration of high-molecular-weight hyaluronic acid (HMW HA) could rescue trinitrobenzene sulfonic acid (TNBS)-induced colitis through Toll-like receptor 4 (TLR4) signal. C3H/HeN mice and C3H/HeJ mice were used. Mice were divided into four groups: control, 50% ethanol treatment group, TNBS treatment group, and TNBS plus HA treatment group. The weight changes, clinical scores, macroscopic scores, and histological scores were recorded. Cyclooxygenase 2 (Cox-2) and prostaglandin E(2) (PGE(2)) expressions were measured both in colons and peritoneal macrophages from these mice. HA was a rescue therapy for the colitis induced by TNBS only in C3H/HeN mice. The clinical score, macroscopic score, and histological score were much lower in C3H/HeN mice receiving TNBS plus HA treatment. Cox-2 and PGE(2) expressions only increased in C3H/HeN mice. These Cox-2 expressing cells were macrophages. HA can also promote the production of Cox-2 and PGE(2) in peritoneal macrophages from C3H/HeN mice. Our data demonstrated that HMW HA can rescue TNBS-induced colitis through inducing Cox-2 and PGE(2) expressions in a TLR4-dependent way. Macrophages may be the effector cells of HMW HA.

Acute Lung Injury Regulation by Hyaluronan

Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS), have high mortality rates with few treatment options. An important regulatory factor in the pathology observed in ALI/ARDS is a disruption of the pulmonary endothelial barrier which, in combination with epithelial barrier disruption, causes leakage of fluid, protein and cells into lung airspaces. Degradation of the glycosaminoglycan, hyaluronan (HA), is involved in reduction of the endothelial glycocalyx, disruption of endothelial cell-cell contacts and activation of HA binding proteins upregulated in ALI/ARDS which promote a loss of pulmonary vascular integrity. In contrast, exogenous administration of high molecular weight HA has been shown to be protective in several models of ALI. This review focuses on the dichotomous role of HA to both promote and inhibit ALI based on its size and the HA binding proteins present. Further, potential therapeutic applications of high molecular weight HA in treating ALI/ARDS are discussed.

Ultraviolet-B irradiation induces differential regulations of hyaluronidase expression and activity in normal human keratinocytes

Skin aging is a complex process determined by genetic factors (intrinsic aging) and environmental factors (extrinsic aging). One of the most influential environmental factor is UV-B irradiation. Hyaluronic acid (HA) is an abundant component of skin extracellular matrix where it plays many roles such as hydration and architectural support. Downregulation of HA during photoaging was reported previously. Changes in expression and function of its degrading enzymes, the hyaluronidases (Hyals) might be involved in this decrease. In the present study, normal human keratinocytes were submitted to increasing doses of UV-B. The mRNA expression of HYAL1, HYAL2 and HYAL3 and the hyaluronidase enzymatic activity were quantified using real-time PCR and a microtiter-based assay, respectively. After UV-B irradiation, HYAL1 mRNA expression was upregulated whereas HYAL2 and HYAL3 mRNAs were downregulated and hyaluronidase enzymatic activity was increased in both cell layer and culture medium. In parallel, immunohistochemical studies performed on UV-B irradiated reconstructed epidermis confirmed that Hyal-1, Hyal-2 and Hyal-3 protein expression were differently regulated by UV-B. Taken together, our results demonstrate that UV-B irradiation induces differential regulations of hyaluronidase expression and enzymatic activity in human keratinocytes. These differential modulations of hyaluronidase expression and activity by UV-B could contribute to cutaneous photoaging.