Hyaluronidase expression in human skin fibroblasts

The Degradation of Hyaluronan in the Skin

Hyaluronan (HA) comprises a fundamental component of the extracellular matrix and participates in a variety of biological processes. Half of the total amount of HA in the human body is present in the skin. HA exhibits a dynamic turnover; its half-life in the skin is less than one day. Nevertheless, the specific participants in the catabolism of HA in the skin have not yet been described in detail, despite the essential role of HA in cutaneous biology. A deeper knowledge of the processes involved will act to support the development of HA-based topical and implantable materials and enhance the understanding of the various related pathological cutaneous conditions. This study aimed to characterize the distribution and activity of hyaluronidases and the other proteins involved in the degradation of HA in healthy human full-thickness skin, the epidermis and the dermis. Hyaluronidase activity was detected for the first time in healthy human skin. The degradation of HA occurred in lysates at an acidic pH. HA gel zymography revealed a single band corresponding to approximately 50 kDa. This study provided the first comprehensive view of the distribution of canonic HA-degrading proteins (HYAL1 and HYAL2) in human skin employing IHF and IHC. Furthermore, contrary to previous assumptions TMEM2, a novel hyaluronidase, as well as CEMIP, a protein involved in HA degradation, were localized in the human epidermis, as well as in the dermis.

Hyaluronic acid-fibrin hydrogels show improved mechanical stability in dermo-epidermal skin substitutes

Human plasma-derived bilayered skin substitutes have been successfully used by our group in different skin tissue engineering applications. However, several issues associated with their poor mechanical properties were observed, and they often resulted in rapid contraction and degradation. In this sense, hydrogels composed of plasma-derived fibrin and thiolated-hyaluronic acid (HA-SH, 0.05-0.2% w/v) crosslinked with poly(ethylene glycol) diacrylate (PEGDA, 2:1, 6:1, 10:1 and 14:1 mol of thiol to moles of acrylate) were developed to reduce the shrinking rates and enhance the mechanical properties of the plasma-derived matrices. Plasma/HA-SH-PEGDA hydrogels showed a decrease in the contraction behaviour ranging from 5% to 25% and an increase in Young's modulus. Furthermore, the results showed that a minimal amount of the added HA-SH was able to escape the plasma/HA-SH-PEGDA hydrogels after incubation in PBS. The results showed that the increase in rigidity of the matrices as well as the absence of adhesion cellular moieties in the second network of HA-SH/PEGDA, resulted in a decrease in contraction in the presence of the encapsulated primary human fibroblasts (hFBs), which may have been related to an overall decrease in proliferation of hFBs found for all hydrogels after 7 days with respect to the plasma control. The metabolic activity of hFB returned to the control levels at 14 days except for the 2:1 PEGDA crosslinking ratio. The metabolic activity of primary human keratinocytes (hKCs) seeded on the hydrogels showed a decrease when high amounts of HA-SH and PEGDA crosslinker were incorporated. Organotypic skins formed in vitro after 21 days with plasma/HA-SH-PEGDA hydrogels with an HA content of 0.05% w/v and a 2:1 crosslinking ratio were up to three times thicker than the plasma controls, evidencing a reduction in contraction, while they also showed better and more homogeneous keratin 10 (K10) expression in the supra-basal layer of the epidermis. Furthermore, filaggrin expression showed the formation of an enhanced stratum corneum for the constructs containing HA. These promising results indicate the potential of using these biomimetic hydrogels as in vitro skin models for pharmaceutical products and cosmetics and future work will elucidate their potential functionality for clinical treatment.

Tumor Cell Associated Hyaluronan-CD44 Signaling Promotes Pro-Tumor Inflammation in Breast Cancer

Cancer has been conceptualized as a chronic wound with a predominance of tumor promoting inflammation. Given the accumulating evidence that the microenvironment supports tumor growth, we investigated hyaluronan (HA)-CD44 interactions within breast cancer cells, to determine whether this axis directly impacts the formation of an inflammatory microenvironment. Our results demonstrate that breast cancer cells synthesize and fragment HA and express CD44 on the cell surface. Using RNA sequencing approaches, we found that loss of CD44 in breast cancer cells altered the expression of cytokine-related genes. Specifically, we found that production of the chemokine CCL2 by breast cancer cells was significantly decreased after depletion of either CD44 or HA. In vivo, we found that CD44 deletion in breast cancer cells resulted in a delay in tumor formation and localized progression. This finding was accompanied by a decrease in infiltrating CD206+ macrophages, which are typically associated with tumor promoting functions. Importantly, our laboratory results were supported by human breast cancer patient data, where increased HAS2 expression was significantly associated with a tumor promoting inflammatory gene signature. Because high levels of HA deposition within many tumor types yields a poorer prognosis, our results emphasize that HA-CD44 interactions potentially have broad implications across multiple cancers.

In vitro investigation of hyaluronan-based polymeric micelles for drug delivery into the skin: The internalization pathway

In our previous research, we concluded that polymeric micelles based on hyaluronic acid are able to penetrate into the deeper layers of skin tissue. The aim of this work was to characterize the mechanisms involved in the uptake by skin cells, which is important for understanding the influence of the carrier composition on the drug penetration. To reach this goal, we used micelles encapsulating curcumin made of oleyl-hyaluronan (HAC18:1) and hexyl-hyaluronan (HAC6) covalently linked with fluorescent Nile Blue. This labeling enabled us to track the micelle-forming derivative and also micelle payload into the keratinocytes and fibroblasts by fluorescent microscopy and flow cytometry. The regulation of both the passive and active cellular uptake was used to determine the mechanism of micelle internalization. Furthermore, the changes of membrane fluidity were measured for these derivatives by FRAP. Using these methods we concluded that carriers entered the cells using both active and passive transport. Passive transport was facilitated by the affinity of the carrier to the cell membrane, especially in the case of HAC18:1 carrier, which changed significantly the membrane fluidity. The active transport was dependent on cell type, but mainly driven by the clathrin-mediated endocytosis and macropinocytosis. Surprisingly, the main HA receptor, CD44, was not involved in the uptake. We can conclude that these carrier systems could be used for the local transport of active substances or hydrophobic drugs into the skin cells using the advantage of passive transport of oleyl-HA derivative.

Use of chromatographic and electrophoretic tools for assaying elastase, collagenase, hyaluronidase, and tyrosinase activity

Elastase, collagenase, hyaluronidase and tyrosinase, are very interesting enzymes due to their direct implication in skin aging and as therapeutic hits. Different techniques can be used to study these enzymes and to evaluate the influence of effectors on their kinetics. Nowadays, analytical techniques have become frequently used tools for miniaturizing enzyme assays. The main intention of this article is to review chromatographic and electrophoretic tools that study the four enzymes above mentioned. More specifically, the use of high-performance liquid chromatography and capillary electrophoresis and their derivative techniques for monitoring these enzymes will be investigated. The advantages and limitations of these assays will also be discussed. The original use of microscale thermophoresis and thin layer chromatography in this domain will also be covered.

Hyaluronan/RHAMM interactions in mesenchymal tumor pathogenesis: role of growth factors

Fibrosarcoma belongs to the sarcoma cancer group, which are spindle cell malignancies of mesenchymal origin, and owe their name to the predominant cell line that is present within the tumor. The extracellular matrix (ECM) is a complicated structure that surrounds and supports cells within tissues. Its main components are proteoglycans, collagens, glycoproteins, hyaluronan (HA), and several matrix-degrading enzymes. During cancer progression, significant changes can be observed in the structural and mechanical properties of ECM components. The ECM provides a physical scaffold to which tumor cells attach and migrate. Thus, it is required for key cellular events such as cell motility, adhesion, proliferation, invasion, and metastasis. Importantly, fibrosarcomas were shown to have a high content and turnover of ECM components including HA, proteoglycans, collagens, fibronectin, and laminin. In this review, we will focus on the HA component of fibrosarcoma ECM and critically discuss its role and involved mechanisms during fibrosarcoma pathogenesis.

More than just a filler - the role of hyaluronan for skin homeostasis

In recent years, hyaluronan (HA) has become an increasingly attractive substance as a non-immunogenic filler and scaffolding material in cosmetic dermatology. Despite its wide use for skin augmentation and rejuvenation, relatively little is known about the molecular structures and interacting proteins of HA in normal and diseased skin. However, a comprehensive understanding of cutaneous HA homeostasis is required for future the development of HA-based applications for skin regeneration. This review provides an update on HA-based structures, expression, metabolism and its regulation, function and pharmacological targeting of HA in skin.

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.

Luteolin prevents solar radiation-induced matrix metalloproteinase-1 activation in human fibroblasts: a role for p38 mitogen-activated protein kinase and interleukin-20 released from keratinocytes

Human skin is continuously exposed to solar radiation, which can result in photoaging, a process involving both dermal and, to a lesser extent, epidermal structures. Previously, we have shown that the flavonoid luteolin protects the epidermis from ultraviolet (UV)-induced damage by a combination of UV-absorbing, antioxidant, and antiinflammatory properties. The aim of the present study was to determine direct and indirect effects of luteolin on dermal fibroblasts as major targets of photoaging. Stimulation of fibroblasts with UVA light or the proinflammatory cytokine interleukin-20 (IL-20) is associated with wrinkled skin, increased IL-6 secretion, matrix metalloproteinase (MMP-1) expression, and hyaluronidase activity. All of these targets were inhibited by luteolin via interference with the p38 mitogen-activated protein kinase (MAPK) pathway. Next, we assessed the role of conditioned supernatants from keratinocytes irradiated with solar-simulated radiation (SSR) on nonirradiated dermal fibroblasts. In keratinocytes, luteolin inhibited SSR-induced production of IL-20, also via interference with the p38 MAPK pathway. Similarly, keratinocyte supernatant-induced IL-6 and MMP-1 expression in fibroblasts was reduced by pretreatment of keratinocytes with luteolin. Finally, these results were confirmed ex vivo on skin explants treated with luteolin before UV irradiation. Our results suggest that SSR-mediated production of soluble factors in keratinocytes is modulated by luteolin and may attenuate photoaging in dermal fibroblasts.

Identification of specific chondroitin sulfate species in cutaneous autoimmune disease

Cutaneous lupus erythematosus and dermatomyositis (DM) are chronic inflammatory diseases of the skin with accumulated dermal mucin. Earlier work has shown chondroitin sulfate (CS) accumulation within the dermis of discoid lupus erythematosus (DLE), subacute cutaneous lupus erythematosus (SCLE), and DM lesions compared with control skin. Immunohistochemistry for C4S revealed a greater density in DLE and DM lesions, whereas SCLE lesions did not differ from controls. Scleredema and scleromyxedema are attributed to increased hyaluronic acid, and lesional samples from these diseases also demonstrated accumulated dermal C4S. Interferon-γ and interleukin-1α, but not interferon-α, treatment of cultured dermal fibroblasts induced mRNA expression of CHST-11, which attaches sulfates to the 4-position of unsulfated chondroitin. These studies on possible CS core proteins revealed that serglycin, known to have C6S side chains in endothelial cells, had greater density within DM dermal endothelia but not in DLE or SCLE, following the pattern of C6S overexpression reported previously. CD44 variants expand the CS binding repertoire of the glycoprotein; CD44v7 co-localized to the distribution of C4S in DLE lesions, a finding not observed in DM, SCLE lesions, or controls. Because C4S and C6S have immunologic effects, their dysregulation in cutaneous mucinoses may contribute to the pathogenesis of these disorders.

Systemic administration of high-molecular weight hyaluronan stimulates wound healing in genetically diabetic mice

Hyaluronic acid (HA), an essential component of the extracellular matrix, is an efficient space filler that maintains hydration, serves as a substrate for assembly of proteoglycans and is involved in wound healing. Although numerous pieces of evidence demonstrate beneficial effects in promoting wound healing in diabetes, a systemic approach has never been tested. We used an incisional wound healing model in genetically diabetic mice to test the effects of systemic injection of HA. Diabetic (n=56) and normoglycemic (n=56) mice were subjected to incision and randomized (8 groups of 7 animals each) to receive HA at different doses, 7.5, 15 and 30mg/kg/i.p., or vehicle (0.9% NaCl solution) for 12days. At the end of the experiment animals were sacrificed and skin wounds were excised for histological, biochemical and molecular analysis. Histology revealed that the most effective dose to improve wound repair and angiogenesis in diabetic mice was 30mg/kg. Furthermore HA injection (30mg/kg) improved the altered healing pattern in diabetic animals, increased skin remodeling proteins TGF-β and transglutaminase-II and restored the altered expression of cyclin B1/Cdc2 complex. Evaluation of skin from diabetic animals injected with HA revealed also an increase in HA content, suggesting that systemic injection may be able to restore the reduced intracellular HA pool of diabetic mice. Finally HA markedly improved skin mechanical properties. These promising results, if confirmed in a clinical setting, may improve the care and management of diabetic patients.

Modulation of hyaluronan catabolism in chondrocytes by mechanical stimuli

Hyaluronan (HA) is a component of the extracellular matrices of cartilage contributing to the structural and functional integrity. HA metabolism is regulated by both anabolic and catabolic processes; however, a great deal more of the detail has been unknown yet. The purpose of this study was to clarify the effect of excessive mechanical load on the expression and activity of hyaluronidase (HYAL) in chondrocytes with a special reference to the expressions of IL-1beta and tumor necrosis factor (TNF)-alpha. A cyclic tensile load of 22.8% cell elongation, regarded as an excessive mechanical stimulus, was applied to cultured rabbit knee articular chondrocytes. HYAL1, HYAL2, IL-1beta, and TNF-alpha mRNA levels were examined by quantitative real-time PCR analysis. The HYAL activity in culture medium was examined by HA zymography. Both HYAL1 and HYAL2 mRNA levels were upregulated significantly by the loading in cultured chondrocytes. HYAL activity was also enhanced as compared with unloaded controls. The IL-1beta mRNA level was upregulated significantly by the loading, and TNF-alpha mRNA level was slightly upregulated. HYAL1 and HYAL2 mRNA levels were upregulated significantly by IL-1beta treatment, resulting in a slight increase in HYAL activity. These results show that the expression of HYAL1 and HYAL2 in articular chondrocytes is enhanced by excessive mechanical stimuli and affected in part by induction of IL-1beta, leading to HA catabolism in articular cartilage.

Thyrotropin receptor activation increases hyaluronan production in preadipocyte fibroblasts: contributory role in hyaluronan accumulation in thyroid dysfunction

The thyrotropin receptor (TSHR) is expressed during lineage-specific differentiation (e.g. adipogenesis) and is activated by TSH, thyroid-stimulating antibodies, and gain-of-function mutations (TSHR*). Comparison of gene expression profiles of nonmodified human preadipocytes (n = 4) with the parallel TSHR* population revealed significant up-regulation of 27 genes including hyaluronan (HA) synthases (HAS) 1 and 2. The array data were confirmed by quantitative PCR of HAS1 and HAS2 and enzyme-linked immunosorbent assay measurement of HA; all values were significantly increased (p < 0.03) in TSHR*-expressing preadipocytes (n = 10). Preadipocytes (n = 8) treated with dibutyryl (db)-cAMP display significantly increased HAS1 and HAS2 transcripts, HAS2 protein, and HA production (p < 0.02). HAS1 or HAS2 small interfering RNA treatment of db-cAMP-stimulated preadipocytes (n = 4) produced 80% knockdown in HAS1 or 61% knockdown in HAS2 transcripts (compared with scrambled), respectively; the corresponding HA production was reduced by 49 or 38%. Reporter assays using A293 cells transfected with HAS1 promoter-driven plasmids containing or not containing the proximal CRE and treated with db-cAMP revealed that it is functional. Chromatin immunoprecipitation, using a cAMP-responsive element-binding protein antibody, of db-cAMP-treated preadipocytes (n = 4) yielded products for HAS1 and HAS2 with relative fold increases of 3.3 +/- 0.8 and 2.6 +/- 0.9, respectively. HA accumulates in adipose/connective tissues of patients with thyroid dysfunction. We investigated the contributions of TSH and thyroid-stimulating antibodies and obtained small (9-24%) but significant (p < 0.02) increases in preadipocyte HA production with both ligands. Similar results were obtained with a TSHR monoclonal antibody lacking biological activity (p < 0.05). We conclude that TSHR activation is implicated in HA production in preadipocytes, which, along with thyroid hormone level variation, explains the HA overproduction in thyroid dysfunction.

Glycosaminoglycan-targeted fixation for improved bioprosthetic heart valve stabilization

Numerous crosslinking chemistries and methodologies have been investigated as alternative fixatives to glutaraldehyde (GLUT) for the stabilization of bioprosthetic heart valves (BHVs). Particular attention has been paid to valve leaflet collagen and elastin stability following fixation. However, the stability of glycosaminoglycans (GAGs), the primary component of the spongiosa layer of the BHV, has been largely overlooked despite recent evidence provided by our group illustrating their structural and functional importance. In the present study we investigate the ability of two different crosslinking chemistries: sodium metaperiodate (NaIO(4)) followed by GLUT (PG) and 1-Ethyl-3-(3 dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) followed by GLUT (ENG) to stabilize GAGs within BHV leaflets and compare resulting leaflet characteristics with that of GLUT-treated tissue. Incubation of fixed leaflets in GAG-degrading enzymes illustrated in vitro resistance of GAGs towards degradation in PG and ENG treated tissue while GLUT fixation alone was not effective in preventing GAG loss from BHV leaflets. Following subdermal implantation, significant amounts of GAGs were retained in leaflets in the ENG group in comparison to GLUT-treated tissue, although GAG loss was evident in all groups. Utilizing GAG-targeted fixation did not alter calcification potential of the leaflets while collagen stability was maintained at levels similar to that observed in conventional GLUT-treated tissue.

Chondrocytes, synoviocytes and dermal fibroblasts all express PH-20, a hyaluronidase active at neutral pH

Hyaluronan (HA), an important component of connective tissues, is highly metabolically active, but the mechanisms involved in its catabolism are still largely unknown. We hypothesized that a protein similar to sperm PH-20, the only mammalian hyaluronidase known to be active at neutral pH, could be expressed in connective tissue cells. An mRNA transcript similar to that of PH-20 was found in chondrocytes, synoviocytes, and dermal fibroblasts, and its levels were enhanced upon stimulation with IL-1. In cell layers extracted with Triton X-100 – but not with octylglucoside – and in culture media, a polyclonal antipeptide anti-PH-20 antibody identified protein bands with a molecular weight similar to that of sperm PH-20 (60 to 65 kDa) and exhibiting a hyaluronidase activity at neutral pH. Further, upon stimulation with IL-1, the amounts of the neutral-active hyaluronidase increased in both cell layers and culture media. These findings contribute potential important new insights into the biology of connective tissues. It is likely that PH-20 facilitates cell-receptor-mediated uptake of HA, while overexpression or uncontrolled expression of the enzyme can cause great havoc to connective tissues: not only does HA fragmentation compromise the structural integrity of tissues, but also the HA fragments generated are highly angiogenic and are potent inducers of proinflammatory cytokines. On the other hand, the enzyme activity may account for the progressive depletion of HA seen in osteoarthritis cartilage, a depletion that is believed to play an important role in the apparent irreversibility of this disease process.

Hyaluronidase expression in cultured growth plate chondrocytes during differentiation

Hyaluronan (HA) is a major component of the extracellular matrix of cartilage, contributes to its structural and functional integrity, and has various important roles in the differentiation of chondrocytes. HA metabolism is regulated by both anabolic and catabolic processes; however, the details have not yet been clarified. The purpose of this study was to clarify the expression patterns of hyaluronidase (HAase) mRNAs (from the relevant HAase genes: the HYALs) and HAase activity during chondrocyte differentiation. Cartilage tissue and growth plate chondrocytes were isolated from the ribs of 4-week-old male Japanese rabbits. The expression of HYAL mRNAs in cartilage was analyzed by in situ hybridization. The expression levels of HYAL mRNAs in the culture were analyzed for each of the chondrocyte differentiation stages by means of quantitative real-time polymerase chain reaction analysis. Enzymatic activity in the conditioned medium from the cultures was examined by using HA zymography and an enzyme-linked immunosorbent-like assay. The expression levels of HYAL1 and HYAL2 mRNAs were enhanced about 2.8-fold and 3.2-fold at the maximum during the early matrix forming stage, respectively, and by about 3.2-fold and 2.0-fold at the maximum in the hypertrophic stage, respectively. HYAL3 mRNA was not detected throughout the experimental period. HAase activity was enhanced at the early matrix forming and hypertrophic stages. These results suggest that selective expression of HYALs is essential for extracellular HA metabolism during chondrocyte differentiation.

Myofibroblastic differentiation leads to hyaluronan accumulation through reduced hyaluronan turnover

During the initiation and progression of fibrosis there is extensive differentiation of cells to a myofibroblastic phenotype. Because the synthesis of hyaluronan (HA) was recently linked to oncogenic epithelial-mesenchymal transformation, the present study investigated whether increased HA synthesis was also associated with myofibroblastic differentiation. HA synthesis and size were measured by incorporation of [(3)H]glucosamine, ion exchange, and size exclusion chromatography. Hyaluronan synthase (HAS) or hyaluronidase (HYAL) mRNA levels were assessed by reverse transcription-PCR. HYAL was detected by immunoblotting and the degradation of [(3)H]HA. Between 2- and 3-fold more HA appeared in the conditioned medium and became associated with the cells upon myofibroblastic differentiation. Inhibition of HAS and examination of HAS mRNA expression demonstrated that this was not the result of increased synthesis of HA or the induction of HAS 2. After differentiation, however, myofibroblasts metabolized exogenously supplied [(3)H]HA at a slower rate than fibroblasts and expressed lower levels of both HYAL 1 and HYAL 2 mRNA. Immunoblotting revealed more HYAL 1 and 2 in the myofibroblast conditioned medium. After acidification, however, there was no difference in HA degradation. This suggests that much of the released HYAL is inactive and that the observed differences in HA degradation are caused by cell-associated rather than secreted activity. This was confirmed by immunohistochemical staining for HYAL 1 and HYAL 2. This finding indicates the potential importance of the HYAL enzymes in controlling fibrotic progression and contrasts HA synthesis as a mediator of oncogenic transformation with that of HA degradation controlling fibrogenic differentiation.

Aberrant serum hyaluronan and hyaluronidase levels in scleroderma

BACKGROUND

Scleroderma, or systemic sclerosis, is characterized by aberrations of extracellular matrix deposition. These changes parallel early stages of wound healing when increased deposition of hyaluronan (HA) and collagen occur. Both processes result ultimately in the formation of fibrotic scar tissue. Activities of HA synthase and hyaluronidase, the enzymes that synthesize and degrade HA, are critical in HA turnover. Both become elevated whenever increased matrix deposition occurs. HA deposition occurs early in wound healing, and increases are documented in the circulation of scleroderma patients. We postulated that elevated HA and hyaluronidase may both be indicators of early-stage disease in scleroderma, in parallel with early changes observed in wound healing. In an attempt to reduce HA accumulation and the associated fibrosis in scleroderma tissues, topical and intravenous hyaluronidase administrations have been used in the past as treatment modalities, with occasional success. This also suggested that hyaluronidase enzyme activity is involved in the disease process. It is now recognized that the hyaluronidases constitute an enzyme family. The somatic hyaluronidase Hyal-1 is the only activity present in human serum.

OBJECTIVES

To determine levels of HA and Hyal-1 in the sera of scleroderma patients at various stages of their disease.

METHODS

Levels of HA and Hyal-1 activity were determined in 25 scleroderma patients. Subjects were separated into two groups, those in the early stage with duration of disease of 2 years or less, and late-stage patients with disease duration of more than 2 years.

RESULTS

In early-stage scleroderma, levels of HA were elevated significantly, as predicted, in comparison with late-stage patients and controls. Late-stage levels of HA were comparable with those found in control sera. By contrast, levels of Hyal-1 activity were normal in early-stage patients, similar to those in controls, but were decreased in late-stage patients, falling even below those of controls.

CONCLUSIONS

We have confirmed that circulating levels of HA are elevated in scleroderma, but show for the first time that such elevations occur predominantly in early-stage disease. Patients with late-stage disease have decreased serum Hyal-1 activity, perhaps reflecting decreased levels of HA turnover. This study also represents the first time that hyaluronidase activity levels have been determined in scleroderma patients.

Expression and activity of hyaluronidase in human periodontal ligament fibroblasts

BACKGROUND

Hyaluronan is a major component of the extracellular matrix of periodontal ligament (PDL) contributing to the structural and functional integrity. Hyaluronans contribute to the buffering effect of the PDL during chewing, and they are also important in inflammation and wound healing. Hyaluronan is known to be synthesized and turned over by the resident PDL cells, although the mechanisms of hyaluronan metabolism still remain unclear. Hyaluronidase (HAase), an endoglycosidase, degrades hyaluronan into small fragments. Currently, 3 human HAases, HYAL1, HYAL2, and PH-20, have been identified and well characterized.

METHODS

This study was conducted to investigate the expression and activity of these HAases in cultured human PDL fibroblasts and to elucidate the mechanisms involved in hyaluronan metabolism under normal and inflammatory conditions. Human PDL fibroblasts derived from the periodontium of 3 premolars were cultured with or without interleukin (IL)-1beta (0.1 to 10 ng/ml) and tumor necrosis factor (TNF)-alpha (1 to 100 ng/ml) for 0 to 48 hours. The expression of HAase mRNA was assessed by reverse transcription-polymerase chain reaction (RT-PCR) and quantitative real-time PCR, and the enzymatic activity was examined using hyaluronan zymography.

RESULTS

PDL fibroblasts expressed HYAL1 and HYAL2 mRNAs, but not PH-20 mRNA. The expression of HYAL1 mRNA was enhanced by about 3.5- and 3.7-fold at maximum after 1-hour stimulation with 1 ng/ml IL-1beta and after 3-hour stimulation with 10 ng/ml TNF-alpha, respectively. The expression of HYAL2 and PH-20 mRNAs was not affected by stimulation with cytokines. HAase activity was detected in conditioned medium from PDL fibroblast cultures, and the activity was enhanced by treatment with 10 ng/ml TNF-alpha.

CONCLUSION

These results suggest that PDL fibroblasts express HAases and generate HAase activity essential for extracellular hyaluronan metabolism under physiological and inflammatory conditions.

Mystixin peptides reduce hyaluronan deposition and edema formation

Hyaluronan and its associated water of hydration are the basis of the swelling and edema of acute inflammation. Mystixins are small, synthetic peptides that suppress the acute inflammatory response. Mystixin-7, a prototype of these peptides, has the structure p-anisoyl-Arg-Lys-Leu-Leu-D-Thi-Ile-D-Leu-NH(2). As shown previously by this laboratory, the mystixin-7 peptide inhibits edema formation in vivo following intravenous administration at doses of less than 1.0 mg/kg. Mechanisms by which this peptide might suppress edema were examined here in vitro using cultured cells. Normal human dermal fibroblasts normally secrete large quantities of hyaluronan in response to inflammatory stimuli. Mystixin-7 reduced hyaluronan deposition by up to 80% in such cultures. Stimulation of hyaluronidase activity was observed. Mystixins represent a novel class of anti-inflammatory peptides that suppress the edema associated with inflammation. We propose that stimulation of hyaluronidase activity, with a decrease in net hyaluronan deposition and its associated water of hydration, is among the mechanisms of the anti-inflammatory effect of mystixin peptides.

Potential mechanism of action of intra-articular hyaluronan therapy in osteoarthritis: are the effects molecular weight dependent?

BACKGROUND

Hyaluronan, or hyaluronic acid (HA), is the major hydrodynamic nonprotein component of joint synovial fluid (SF). Its unique viscoelastic properties confer remarkable shock absorbing and lubricating abilities to SF, while its enormous macromolecular size and hydrophilicity serve to retain fluid in the joint cavity during articulation. HA restricts the entry of large plasma proteins and cells into SF but facilitates solute exchange between the synovial capillaries and cartilage and other joint tissues. In addition, HA can form a pericellular coat around cells, interact with proinflammatory mediators, and bind to cell receptors, such as cluster determinant (CD)44 and receptor for hyaluronate-mediated motility (RHAMM), where it modulates cell proliferation, migration, and gene expression. All these physicochemical and biologic properties of HA have been shown to be molecular weight (MW) dependent.

OBJECTIVE

Intra-articular (IA) HA therapy has been used for the treatment of knee osteoarthritis (OA) for more than 30 years. However, the mechanisms responsible for the reported beneficial clinical effects of this form of treatment remain contentious. Furthermore, there are a variety of pharmaceutic HA preparations of different MW available for the treatment of OA, but the significance of their MWs with respect to their pharmacologic activities have not been reviewed previously. The objective of the present review is to redress this deficiency.

METHODS

We reviewed in vitro and in vivo reports to identify those pharmacologic activities of HA that were considered relevant to the ability of this agent to relieve symptoms and protect joint tissues in OA. Where possible, reports were selected for inclusion when the pharmacologic effects of HA had been studied in relation to its MW. In many studies, only a single HA preparation had been investigated. In these instances, the experimental outcomes reported were compared with similar studies undertaken with HAs of different MWs.

RESULTS

Although in vitro studies have generally indicated that high MW-HA preparations were more biologically active than HAs of lower MW, this finding was not confirmed using animal models of OA. The discrepancy may be partly explained by the enhanced penetration of the lower MW HA preparation through the extracellular matrix of the synovium, thereby maximizing its concentration and facilitating its interaction with target synovial cells. However, there is accumulating experimental evidence to show that the binding of HAs to their cellular receptors is dependent on their molecular size; the smaller HA molecular species often elicits an opposite cellular response to that produced by the higher MW preparations. Studies using large animal models of OA have shown that HAs with MWs within the range of 0.5 x 10(6)-1.0 x 10(6) Da were generally more effective in reducing indices of synovial inflammation and restoring the rheological properties of SF (visco-induction) than HAs with MW > 2.3 x 10(6) Da. These experimental findings were consistent with light and electron microscopic studies of synovial membrane and cartilage biopsy specimens obtained from OA patients administered 5 weekly IA injections of HA of MW = 0.5 x 10(6)-0.73 x 10(6) Da in which evidence of partial restoration of normal joint tissue metabolism was obtained.

CONCLUSIONS

By mitigating the activities of proinflammatory mediators and pain producing neuropeptides released by activated synovial cells, HA may improve the symptoms of OA. In addition, HAs within the MW range of 0.5 x 10(6)-1.0 x 10(6) Da partially restore SF rheological properties and synovial fibroblast metabolism in animal models. These pharmacologic activities of HA could account for the reported long-term clinical benefits of this OA therapy. However, clinical evidence has yet to be described to support the animal studies that indicated that HAs with MW > 2.3 x 10(6) Da may be less effective in restoring SF rheology than HAs of half this size.

Overexpression of hyaluronan synthase-2 reduces the tumorigenic potential of glioma cells lacking hyaluronidase activity

OBJECTIVE

The interactions of CD44 with hyaluronan are thought to be crucial for tumor cell attachment to the extracellular matrix, migration, and invasion. For migration to occur, however, the interactions between hyaluronan and cell surface receptors need to be transient. Hyaluronidases may facilitate the degradation of hyaluronan bound to the cell surface and thus reduce the interactions of the cells with the matrix, whereas the overproduction of hyaluronan in the absence of hyaluronidase activity may prevent cells from proliferating or invading normal surrounding tissue.

METHODS

We analyzed the effects in vitro and in vivo of hyaluronan synthase-2 (HAS2) overexpression on a murine glioma cell line that is deficient in hyaluronidase activity. In addition, we evaluated the expression levels of HAS and hyaluronidase genes in human glioma cell lines and in glioma specimens.

RESULTS

Increased hyaluronan synthesis had no effect on the in vitro proliferation of the cells but diminished their in vivo growth rate. Several human glioma cell lines were found to overexpress hyaluronan synthases, but they did so in conjunction with hyaluronidase Hyal2 and MGEA5 expression. Similarly, all glioblastomas multiforme expressed hyaluronidases MGEA5 and Hyal2.

CONCLUSION

The data suggest that an increased synthesis of hyaluronan by astrocytoma cells is only promoting tumor cell growth in vivo if the cells express hyaluronidases as well.

Hyaluronidases and CD44 undergo differential modulation during chondrogenesis

Hyaluronan, a high-molecular-weight glycosaminoglycan of cartilage, is deposited directly into the extracellular space by hyaluronan synthases, while hyaluronan catabolism is mediated by the hyaluronidases. An in vitro cell culture system has been established in which human dermal fibroblasts are induced to undergo chondrogenesis. Here, we describe the differential modulation of the hyaluronidases and the up-regulation of the hyaluronan receptor, CD44, during such chondrogenesis. Dermal fibroblasts, plated in micromass cultures in the presence of lactic acid and staurosporine for 24 h, were then placed in serum-free, chemically defined medium. At 3 days, RNA was extracted and RT-PCR performed using primers for the hyaluronidase genes. Marked increase in HYAL1 expression was observed, with only moderate increases occurring in HYAL2 and HYAL3. No expression of HYAL4 and PH-20, the sperm-associated hyaluronidase, was detected. RNA levels correlated well with changes in hyaluronidase enzyme activity. Finally, greater expression and staining for the hyaluronan receptor, CD44s, the standard form, were detected. Differential expression of the somatic hyaluronidases and CD44-mediated hyaluronan turnover play a critical role in cartilage development from mesenchymal precursors.

Testicular hyaluronidase induces tubular structures of endothelial cells grown in three-dimensional collagen gel through a CD44-mediated mechanism

Cultured brain capillary endothelial cells grown in a 3-dimensional collagen gel can form tubular structures after stimulation by angiogenic factors. We found that treatment of such cultures with testicular hyaluronidase led to formation of tubular structures and cell survival. Anion-exchange chromatography of the enzyme preparation on a MonoQ column revealed the presence of the angiogenic factor basic fibroblast growth factor (bFGF) in the flow-through fraction, as determined by immunoblotting; part of the effect on endothelial cell morphogenesis could thus be ascribed to bFGF. However, adsorbed fractions eluted with increasing concentrations of NaCl, which exhibited hyaluronan-degrading activity at neutral pH, did not contain bFGF but were still able to induce tube-like structures of the endothelial cells. Streptomyces hyaluronidase failed to evoke the same effect. Interestingly, blocking of hyaluronan binding to CD44 receptors by the monoclonal antibody KM114 inhibited the effect of hyaluronidase, but not of bFGF, on endothelial cell tube formation. Our data suggest a CD44-mediated specific role for certain populations of testicular hyaluronidase in the induction of angiogenesis.

The six hyaluronidase-like genes in the human and mouse genomes

The human genome contains six hyaluronidase-like genes. Three genes (HYAL1, HYAL2 and HYAL3) are clustered on chromosome 3p21.3, and another two genes (HYAL4 and PH-20/SPAM1) and one expressed pseudogene (HYALP1) are similarly clustered on chromosome 7q31.3. The extensive homology between the different hyaluronidase genes suggests ancient gene duplication, followed by en masse block duplication, events that occurred before the emergence of modern mammals. Very recently we have found that the mouse genome also has six hyaluronidase-like genes that are also grouped into two clusters of three, in regions syntenic with the human genome. Surprisingly, the mouse ortholog of HYALP1 does not contain any mutations, and unlike its human counterpart may actually encode an active enzyme. Hyal-1 is the only hyaluronidase in mammalian plasma and urine, and is also found at high levels in major organs such as liver, kidney, spleen, and heart. A model is proposed suggesting that Hyal-2 and Hyal-1 are the major mammalian hyaluronidases in somatic tissues, and that they act in concert to degrade high molecular weight hyaluronan to the tetrasaccharide. Twenty-kDa hyaluronan fragments are generated at the cell surface in unique endocytic vesicles resulting from digestion by the glycosylphosphatidyl-inositol-anchored Hyal-2, transported intracellularly by an unknown process, and then further digested by Hyal-1. The two beta-exoglycosidases, beta-glucuronidase and beta-N-acetyl glucosaminidase, remove sugars from reducing termini of hyaluronan oligomers, and supplement the hyaluronidases in the catabolism of hyaluronan.

Hyaluronan digestion and synthesis in an experimental model of metastatic tumour

To approach the question of hyaluronan catabolism in tumours, we have selected the cancer cell line H460M, a highly metastatic cell line in the nude mouse. H460M cells release hyaluronidase in culture media at a high rate of 57 pU/cell/h, without producing hyaluronan. Hyaluronidase was measured in the H460M cell culture medium at the optimum pH 3.8, and was not found above pH 4.5, with the enzyme-linked sorbent assay technique and zymography. Tritiated hyaluronan was digested at pH 3.8 by cells or cell membranes as shown by gel permeation chromatography, but no activity was recorded at pH 7 with this technique. Hyaluronan was digested in culture medium by tumour slices, prepared from tumours developed in nude mice grafted with H460M cells, showing that hyaluronan could be digested in complex tissue at physiological pH. Culture of tumour slices with tritiated acetate resulted in the accumulation within 2 days of radioactive macromolecules in the culture medium. The radioactive macromolecular material was mostly digested by Streptomyces hyaluronidase, showing that hyaluronan was its main component and that hyaluronan synthesis occurred together with its digestion. These results demonstrate that the membrane-associated hyaluronidase of H460M cells can act in vivo, and that hyaluronan, which is synthesised by the tumour stroma, can be made soluble and reduced to a smaller size by tumour cells before being internalised and further digested.

Hyaluronidase activation of c-Jun N-terminal kinase is necessary for protection of L929 fibrosarcoma cells from staurosporine-mediated cell death

Hyaluronidase counteracts the growth inhibitory function of transforming growth factor beta (TGF-beta), whereas secretion of autocrine TGF-beta and hyaluronidase is necessary for progression and metastasis of various cancers. Whether hyaluronidase and TGF-beta1 induce resistance to staurosporine in L929 fibrosarcoma cells was investigated. When pretreated with TGF-beta1 for 1-2 h, L929 cells resisted staurosporine apoptosis. In contrast, without pretreatment, hyaluronidase protected L929 cells fromstaurosporine apoptosis. Hyaluronidase rapidly activated p42/44 MAPK (or ERK) in L929 cells and TGF-beta1 retarded the activation. Nonetheless, TGF-beta1 synergistically increased hyaluronidase-mediated inhibition of staurosporine apoptosis. Hyaluronidase rapidly activated c-Jun N-terminal kinase (JNK1 and JNK2) in L929 cells in 20 min. Dominant negative JNK1, JNK2, and JNK3 abolished the hyaluronidase inhibition of staurosporine apoptosis, but not the TGF-beta1 protective effect. Unlike the resistance to staurosporine, pretreatment of L929 cells with hyaluronidase is necessary to generate resistance to other anticancer drugs, including doxorubicin, daunorubicin, actinomycin D, and camptothecin, and the induced resistance was also blocked by dominant-negative JNKs. Together, hyaluronidase-mediated JNK activation is necessary to generate resistance to various anticancer drugs in L929 cells.

Stromal and epithelial expression of tumor markers hyaluronic acid and HYAL1 hyaluronidase in prostate cancer

Hyaluronic acid (HA), a glycosaminoglycan, regulates cell adhesion and migration. Hyaluronidase (HAase), an endoglycosidase, degrades HA into small angiogenic fragments. Using an enzyme-linked immunosorbent assay-like assay, we found increased HA levels (3-8-fold) in prostate cancer (CaP) tissues when compared with normal (NAP) and benign (BPH) tissues. The majority ( approximately 75-80%) of HA in prostate tissues was found to exist in the free form. Primary CaP fibroblast and epithelial cells secreted 3-8-fold more HA than respective NAP and BPH cultures. Only CaP epithelial cells and established CaP lines secreted HAase and the secretion increased with tumor grade and metastasis. The pH activity profile and optimum (4.2; range 4.0-4.3) of CaP HAase was identical to the HYAL1-type HAase present in human serum and urine. Full-length HYAL1 transcript and splice variants were detected in CaP cells by reverse transcriptase-polymerase chain reaction, cloning, and sequencing. Immunoblotting confirmed secretion of a approximately 60-kDa HYAL1-related protein by CaP cells. Immunohistochemistry showed minimal HA and HYAL1 staining in NAP and BPH tissues. However, a stromal and epithelial pattern of HA and HYAL1 expression was observed in CaP tissues. While high HA staining was observed in tumor-associated stroma, HYAL1 staining in tumor cells increased with tumor grade and metastasis. The gel-filtration column profiles of HA species in NAP, BPH, and CaP tissues were different. While the higher molecular mass and intermediate size HA was found in all tissues, the HA fragments were found only in CaP tissues. In particular, the high-grade CaP tissues, which showed both elevated HA and HYAL1 levels, contained angiogenic HA fragments. The stromal-epithelial HA and HYAL1 expression may promote angiogenesis in CaP and may serve as prognostic markers for CaP.