Expression of proteoglycans and hyaluronan during wound healing

Strategies to enhance transductional efficiency of adenoviral-based gene transfer to primary human fibroblasts and keratinocytes as a platform in dermal wounds

Genetically modified keratinocytes and fibroblasts are suitable for delivery of therapeutic genes capable of modifying the wound healing process. However, efficient gene delivery is a prerequisite for successful gene therapy of wounds. Whereas adenoviral vectors (Ads) exhibit superior levels of in vivo gene transfer, their transductional efficiency to cells resident within wounds may nonetheless be suboptimal, due to deficiency of the primary adenovirus receptor, coxsackie-adenovirus receptor (CAR). We explored CAR-independent transduction to fibroblasts and keratinocytes using a panel of CAR-independent fiber-modified Ads to determine enhancement of infectivity. These fiber-modified adenoviral vectors included Ad 3 knob (Ad5/3), canine Ad serotype 2 knob (Ad5CAV-2), RGD (Ad5.RGD), polylysine (Ad5.pK7), or both RGD and polylysine (Ad5.RGD.pK7). To evaluate whether transduction efficiencies of the fiber-modified adenoviral vectors correlated with the expression of their putative receptors on keratinocytes and fibroblasts, we analyzed the mRNA levels of CAR, alpha upsilon integrin, syndecan-1, and glypican-1 using quantitative polymerase chain reaction. Analysis of luciferase and green fluorescent protein transgene expression showed superior transduction efficiency of Ad5.pK7 in keratinocytes and Ad5.RGD.pK7 in fibroblasts. mRNA expression of alpha upsilon integrin, syndecan-1 and glypican-1 was significantly higher in primary fibroblasts than CAR. In keratinocytes, syndecan-1 expression was significantly higher than all the other receptors tested. Significant infectivity enhancement was achieved in keratinocytes and fibroblasts using fiber-modified adenoviral vectors. These strategies to enhance infectivity may help to achieve higher clinical efficacy of wound gene therapy.

Keratinocyte-secreted laminin 5 can function as a transient receptor for human papillomaviruses by binding virions and transferring them to adjacent cells

Human papillomaviruses (HPVs) replicate only in the terminally differentiating epithelium of the skin and mucosa. While infection of basal keratinocytes is considered a requirement for permissive infection, it remains unclear whether virions can specifically target basal cells for adsorption and uptake following epithelial wounding. We present evidence that HPV binds specifically to laminin 5 (LN5), a component of the extracellular matrix (ECM) secreted by migrating and basal keratinocytes. HPV type 11 capsids colocalized with LN5 in the ECM secreted by vaginal keratinocytes. Binding of both virions and virus-like particles to purified LN5 and to the LN5-rich ECM secreted by cultured keratinocytes was effectively blocked by pretreatment with anti-LN5 antibodies. HPV capsid binding to human cervical mucosa sections included the basement membrane which contains LN5. Cultured keratinocytes expressing alpha6 integrin, a transmembrane protein known to bind LN5, were readily infected by virions preadsorbed to LN5-containing substrates, whereas mutant keratinocytes lacking alpha6 integrin were relatively resistant to infection via this route. These findings suggest a model of natural HPV infection in which proliferating keratinocytes expressing alpha6 integrin at the site of epithelial wounding might be targeted by virions adsorbed transiently to LN5 secreted by migrating keratinocytes.

Hyaluronic acid inhibits the adherence and growth of monolayer keratinocytes but does not affect the growth of keratinocyte epithelium

Hyaluronic acid (HA) is involved in epidermal biology but evidence for its functional significance is sparse. In this study, low-calcium monolayer and high-calcium epithelium cultures of human keratinocytes were used to study the effect of up to four different HA preparations on keratinocyte growth and on the adherence of proliferating keratinocytes onto the plastic surface coated with different matrix proteins. In suboptimally growing monolayer culture, up to 1,000 microg/ml rooster comb HA and streptococcus equi HA inhibited keratinocyte growth. Instead, all HA preparations tested did not affect the growth and migration of keratinocyte epithelium using optimal or suboptimal growth conditions. In the cell adherence assays, up to 1,000 microg/ml rooster comb HA and streptococcus equi HA inhibited the keratinocyte adherence onto the fibronectin- and collagen-coated substratum. In contrast to other HA preparations, HA from human umbilical cord did not affect the growth of monolayer keratinocytes and it increased markedly the cell adherence onto the collagen-coated substratum. This increase, however, can be attributed to chonroitin sulphate proteoglycan contaminant present in this HA preparation. In conclusion, HA can inhibit the growth and adherence of proliferating monolayer keratinocytes, but it has no apparent effect on the growth and migration of keratinocyte epithelium.

A role for decorin in cutaneous wound healing and angiogenesis

Decorin is known to influence tissue tensile strength and cellular phenotype. Therefore, decorin is likely to have an impact on tissue repair, including cutaneous wound healing. In this study, cutaneous healing of both excisional and incisional full-thickness dermal wounds was studied in decorin-deficient (Dcn(-/-)) animals. A statistically significant delay in excisional wound healing in the Dcn(-/-) mice occurred at 4 and 10 days postwounding and, in incisional wounds at 4, 10, and 18 days when compared with wild-type (Dcn(-/-)) controls. Fibrovascular invasion into polyvinylalcohol sponges was significantly increased by day 18 in Dcn(-/-) mice relative to Dcn(+/+) mice. The 18-day sponge implants in the Dcn(-/-) mice showed a marked accumulation of biglycan when compared with the corresponding implants in Dcn(+/+) mice. Thus, regulated production of decorin may serve as an excellent therapeutic approach for modifying impaired wound healing and harmful foreign body reactions.

Increased mesangial cell hyaluronan expression in lupus nephritis is mediated by anti-DNA antibody-induced IL-1beta

The mechanism by which anti-DNA antibodies contribute to the pathogenesis of lupus nephritis (LN) remains to be fully elucidated. Hyaluronan (HA) is an important extracellular matrix constituent that accumulates during tissue injury, and participates in lymphocyte recruitment to sites of inflammation. The role of HA in the pathogenesis of LN has not been defined. We investigated the expression of HA in renal biopsies and circulating HA levels in patients with diffuse proliferative LN, and the effect of human anti-DNA antibodies on HA synthesis in cultured human mesangial cells (HMC). HA expression was increased in the mesangium, and in the periglomerular and tubular distribution in LN kidney biopsies. LN patients showed increased levels of circulating HA, especially during active disease, which correlated with anti-DNA antibody titers (r=0.35, P=0.0234). Anti-DNA antibodies isolated during active LN but not remission increased de novo synthesis of (3)H-labeled HA, which was accompanied by induction of HA synthase (HAS) II transcription, and enhanced IL-1beta, IL-6, and tumor necrosis factor-alpha secretion in HMC (P<0.001 for all). Only anti-DNA antibody induction of IL-1beta enhanced HA synthesis, which was abrogated by inhibitors of de novo mRNA or protein synthesis. Our findings demonstrate that HA expression is significantly increased within the mesangium in diffuse proliferative LN mediated through anti-DNA antibody-induced IL-1beta. Given that HA plays a pivotal role during inflammatory responses, influences cellular behavior and assists in the recruitment of lymphocytes to sites of injury, it is likely that HA contributes to the pathogenesis of LN.

Human papillomaviruses bind a basal extracellular matrix component secreted by keratinocytes which is distinct from a membrane-associated receptor

Human papillomaviruses (HPVs) have previously been shown to adsorb to cultured cells via membrane-associated heparan sulfate (HS) and alpha6 integrin. We demonstrate that cultured keratinocytes uniquely secrete a component into the basal extracellular matrix (ECM) which can function to adsorb HPV particles which can then be internalized by adherent cells. This uncharacterized basal ECM adsorption receptor was secreted by normal human epidermal keratinocytes (NHEK) and by each of the four keratinocyte-derived cell lines we examined, but not by non-keratinocyte cell lines. Multiple HPV types bound preferentially to this keratinocyte-specific receptor over the membrane-associated receptor, and binding to the basal ECM adsorption receptor was refractory to inhibition by heparin. Like the membrane-associated receptor, this basal ECM component was functional as an adsorption receptor in our in vitro infection model using HPV-11. Unlike particle adsorption, however, successful infection with HPV-11 virions remained sensitive to the pretreatment of virions with heparin. The secreted basal ECM receptor did not colocalize with antibodies against HS, perlecan, or alpha6 integrin, but colocalized with antibody against laminin-5, a marker of keratinocyte ECM and an abundant component of the basement membrane in mucosa and skin. These findings suggest a model for natural infections in which HPV virions, nonspecifically adsorbed to HS on suprabasal keratinocytes throughout an epithelial wound, might be transferred to mitotically active migrating keratinocytes via an intermediate association with the ECM secreted by these cells as they reestablish the basement membrane.

TGF-beta induced hyaluronan synthesis in orbital fibroblasts involves protein kinase C betaII activation in vitro

Graves' ophthalmopathy is accompanied by hyaluronan (HA) accumulation in the orbital space and infiltration of immunocompetent cells and cytokines, including IFN-gamma, IL-1beta, and TGF-beta. We examined the signal transduction pathways by which TGF-beta induces HA synthesis in normal orbital fibroblasts, orbital fibroblasts from patients with Graves' ophthalmopathy, and abdominal fibroblasts. Calphostin C inhibited the stimulation of HA synthesis by TGF-beta. Phorbol 12-myristate 13-acetate (PMA) activation of PKC stimulated HA production. The effects of TGF-beta and PMA were not synergistic. Stimulation by TGF-beta and PMA were dependent on protein synthesis and their effects were inhibited by cycloheximide. Since TGF-beta-induced HA synthesis was inhibited by BAPTA or by PKC inhibitors, a calcium-dependent PKC was most likely involved. The PKA inhibitor H-89 enhanced TGF-beta- and PMA-induced HA synthesis, thus showing that communication between the PKA and PKC pathways was evident. TGF-beta stimulated the translocation of PKCbetaII to the cell membrane. PKCbetaII, a key enzyme in the regulation of HA synthesis by TGF-beta, might be an appropriate target for therapeutic compounds to be used to treat Graves' ophthalmopathy accompanied by inflammation.

Syndecans: new kids on the signaling block

Cell-associated proteoglycans provide highly complex and sophisticated systems to control interactions of extracellular cell matrix components and soluble ligands with the cell surface. Syndecans, a conserved family of heparan- and chondroitin-sulfate carrying transmembrane proteins, are emerging as central players in these interactions. Recent studies have demonstrated the essential role of syndecans in modulating cellular signaling in embryonic development, tumorigenesis, and angiogenesis. In this review, we focus on new advances in our understanding of syndecan-mediated cell signaling.

Porphyromonas gingivalis lipopolysaccharide induces shedding of syndecan-1 expressed by gingival epithelial cells

Syndecans are constitutively shed from growing epithelial cells as the part of normal cell surface turnover. However, increased serum levels of the soluble syndecan ectodomain have been reported to occur during bacterial infections. The aim of this study was to evaluate the potential of lipopolysaccharide (LPS) from the periodontopathogen Porphyromonas gingivalis to induce the shedding of syndecan-1 expressed by human gingival epithelial cells. We showed that the syndecan-1 ectodomain is constitutively shed from the cell surface of human gingival epithelial cells. This constitutive shedding corresponding to the basal level of soluble syndecan-1 ectodomain was significantly increased when cells were stimulated with P. gingivalis LPS and reached a level comparable to that caused by phorbol myristic acid (PMA), an activator of protein kinase C (PKC) which is well known as a shedding agonist. The syndecan-1 shedding was paralleled by pro-inflammatory cytokine interleukin-1 beta (IL-1beta), IL-6, IL-8, and tumor necrosis factor alpha (TNF-alpha) release. Indeed, secretion of IL-1beta and TNF-alpha increased following stimulation by P. gingivalis LPS and PMA, respectively. When recombinant forms of these proteins were added to the cell culture, they induced a concentration-dependent increase in syndecan-1 ectodomain shedding. A treatment with IL-1beta converting enzyme (ICE) specific inhibitor prevented IL-1beta secretion by epithelial cells stimulated by P. gingivalis LPS and decreased the levels of shed syndecan-1 ectodomain. We also observed that PMA and TNF-alpha stimulated matrix metalloproteinase-9 secretion, whereas IL-1beta and P. gingivalis LPS did not. Our results demonstrated that P. gingivalis LPS stimulated syndecan-1 shedding, a phenomenon that may be mediated in part by IL-1beta, leading to an activation of intracellular signaling pathways different from those involved in PMA stimulation.

Syndecan-1 Expression During the Formation of Junctional Epithelium

BACKGROUND

Syndecans are cell surface heparan sulfate proteoglycans (PG) which can bind to and modulate the action of growth factors and extracellular matrix components (ECM). Syndecan- 1 has been shown to play important roles during early tooth development and wound healing and repair. Among diverse cells and tissues that comprise the periodontium, the junctional epithelium (JE) constitutes a region of significant anatomic and clinical importance, but the nature of inductive signals and molecules involved in its formation is still unclear. Therefore, this work examines if syndecan-1 is associated with formation of JE, and the distribution of other syndecan family members in the epithelium.

METHODS

In situ hybridization and immunohistochemical techniques were performed using oral tissues from 4-day-old to 10-week-old mice to investigate the expression of syndecan- 1, -2, -3 and -4 mRNAs and their corresponding proteins.

RESULTS

Based on in situ hybridization experiments, all syndecan mRNAs were detected in sulcular epithelium (SE), gingival epithelium (GE), and JE with varying intensity and distribution. Syndecan-1 immunostaining was localized on the cell surface while that of syndecan-2 did not show clear membrane localization. Our experiments in the developing tooth demonstrated that syndecan-1 protein followed characteristic patterns of expression during JE formation and that immunoreactivity for syndecan-1 protein decreased with age when JE cells underwent terminal differentiation.

CONCLUSION

Results of syndecan-1 mRNA and protein expression patterns suggested that this proteoglycan might be an important molecule during the formation of JE.

Localization of epidermal hyaluronan in the foot pads of the North American raccoon (Procyon lotor)

The localization of the epidermal hyaluronan in the digital foot pads of the North American raccoon (Procyon lotor) was examined by light and electron microscopic histochemical methods. The thick epidermis contained five epidermal layers composed of typical keratinocytes. In the stratum basale and stratum spinosum, hyaluronic acid was clearly detectable at cytoplasmic processes, in close vicinity to the surface coat of the plasma membrane, and/or in the intercellular space between the basal and spinous cells. The results suggest that epidermal hyaluronan that fills the intercellular space may particularly control water maintenance in the epidermis of the raccoon digital pads to guarantee the optimal mechanoreceptive function of the very specific and sensitive sensoric subepidermal equipment in this mammalian species.

Fibroblast growth factor-2 regulates the synthesis of hyaluronan by human periodontal ligament cells

Basic fibroblast growth factor (FGF-2) can enhance biological potentials of periodontal ligament cells and its topical application induces considerable periodontal tissue regeneration in vivo. In this study, we examined the effect of FGF-2 on the production of hyaluronan (HA), an extracellular matrix playing important roles in homeostasis and inflammatory/wound healing responses, by human periodontal ligament (HPDL) cells. An inhibition binding-protein assay revealed that FGF-2 significantly increased HA production by HPDL cells in a dose dependent manner. Analysis by HPLC revealed that in conditioned medium of FGF-2-treated HPDL cells HA had a higher molecular mass, compared to that of untreated HPDL cells. RT-PCR analysis revealed the enhancement of mRNA expression of hyaluronan synthase (HAS) 1 and HAS 2, both of which contribute to the production of HA with a high molecular mass, but not HAS 3 in the FGF-2-treated HPDL cells. In contrast, three isoforms of hyaluronidase (HYAL) transcript were unchanged in the FGF-2-treated HPDL cells. These results provide new evidence for the possible involvement of FGF-2 in the regulation of HA production and its appreciable roles in not only homeostasis but also regeneration of periodontal tissues.

The macrophage-activating lipopeptide-2 accelerates wound healing in diabetic mice

Wound healing in healthy individuals proceeds at an optimal rate. However, in patients, with -- e.g.-- locally impaired blood flow or diabetes, chronic wounds develop and often become infected. Chronic wounds mean a low quality of life for the afflicted patients, not to mention enormous costs. Rather than using recombinant growth factors to accelerate wound healing, we employed the toll-like receptor agonist macrophage-activating lipopeptide-2 (MALP-2) to improve the healing of full-thickness excision skin wounds in an animal model with obese, diabetic mice. A gene array experiment suggested that MALP-2 stimulates the release of various mediators involved in wound healing. Further data to be presented in this study will show (i) that MALP-2 is capable of stimulating the appearance of the monocyte chemoattractant protein-1 at the wound site, (ii) that this leads to increased leucocyte and, in particular, macrophage infiltration and (iii) that MALP-2-treated wounds closed 2 weeks earlier than vehicle-treated controls. MALP-2, thus, appears to stimulate the early inflammatory process needed to set in motion the ensuing consecutive natural steps of wound healing resulting in wound closure.

Hyaluronan participates in the epidermal response to disruption of the permeability barrier in vivo

Hyaluronan (hyaluronic acid, HA) is a glycosaminoglycan in the extracellular matrix of tissues that plays a role in cellular migration, proliferation and differentiation. Injury to the stratum corneum elicits an epidermal hyperproliferative response, a pathogenic feature in many cutaneous diseases including eczema and psoriasis. Because HA is abundant in the matrix between keratinocytes, we asked whether the presence of HA is required for epidermal hyperplasia to occur in response to barrier injury. Disruption of the stratum corneum, by acetone application on the skin of hairless mice, led to a marked accumulation of HA in the matrix between epidermal basal and spinous keratinocytes, and also within keratinocytes of the upper epidermis. To test whether HA may have a functional role in epidermal hyperplasia, we used Streptomyces hyaluronidase (StrepH), delivered topically, to degrade epidermal HA and blunt the accumulation of epidermal HA after acetone. StrepH signficantly reduced epidermal HA levels, and also significantly inhibited the development of epidermal hyperplasia. This reduction in epidermal thickness was not attributable to any decrease in keratinocyte proliferation, but rather to an apparent acceleration in terminal differentiation (ie, increased keratin 10 and filaggrin expression). Overall, the data show that HA is a significant participant in the epidermal response to barrier injury.

Clinical and microbiological effects of topical subgingival application of hyaluronic acid gel adjunctive to scaling and root planing in the treatment of chronic periodontitis

BACKGROUND

Hyaluronic acid (HA) has shown anti-inflammatory effects in gingivitis therapy. The potential benefits of local subgingival application of HA adjunctive to scaling and root planing (SRP) were evaluated in this study.

METHODS

Twenty patients with chronic periodontitis were included in this split-mouth study. Sulcus fluid flow rate (SFFR) and sulcus bleeding index were monitored at baseline and after 1, 2, 3, 4, 5, 6, and 12 weeks; probing depth and clinical attachment level were monitored at baseline and 6 and 12 weeks. Subgingival plaque samples were also taken at these same three appointments to determine the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Treponema denticola. All patients were treated with full-mouth scaling and root planing (SRP); in addition, an HA gel was administered subgingivally in the test sites every week for 6 weeks.

RESULTS

An improvement of all clinical variables was observed (P < 0.05) in both groups. Clinically, no difference between test and control sites could be found. No difference between test and control sites was seen in the tested microorganisms.

CONCLUSIONS

No clinical or microbiological improvement was achieved by the adjunctive use of HA gel compared to SRP alone. Only SFFR was affected by the use of HA in terms of a more rapid reduction of SFFR in the test sites.

Stimulation of porcine bone marrow stromal cells by hyaluronan, dexamethasone and rhBMP-2

In the interest of optimizing osteogenesis in in vitro, the present study sought to determine how porcine bone marrow stromal cell (BMSc) would respond to different concentrations of hyaluronan (HY) and its different combinations with dexamethasone (Dex) and recombinant human bone morphogenic protein-2 (rhBMP-2). Cellular proliferation was determined by 3H-thymidine incorporation into DNA at both Days 2 and 7 when BMSc was cultivated with HY at concentrations of 0, 0.5, 1.0, 2.0 and 4.0 mg/ml. HY accelerated cellular proliferation when compared with cultures in the absence of HY at both Days 2 and 7. BMSc proliferation under the high HY concentration of 4 mg/ml was significantly higher than under the other, lower HY concentrations of 0.5, 1.0 and 2.0 mg/ml. When BMSc were cultivated under HY at concentrations of 0, 1.0 and 4.0 mg/ml and its 12 combinations with rhBMP-2 at concentrations of 0 and 10 ng/ml and Dex (+, -) at both Days 2 and 7, cellular responses were examined by 3H-thymidine incorporation into DNA, cellular alkaline phosphatase (ALP) activity, and pro-collagen type I C-terminal propeptide production. HY accelerated cellular proliferation irrespective of the presence of Dex and rhBMP-2. HY increased expression of ALP activity at Day 7, whereas had inhibitory effect at Day 2. HY and Dex showed an interaction on expression of ALP acitivity irrespective of the HY dose by Day 7. Collagen synthesis was inhibited by HY irrespective of the presence of other factors at both Days 2 and 7. When BMSc were cultivated with HY of 4.0 mg/ml alone, its combinations with Dex (+) and 10 ng/ml rhBMP-2, and with DMEM/FBS alone, expression of bone-related marker genes was evaluated by real-time reverse transcription-polymerase chain reaction (Real-time RT-PCR) analysis. Osteocalcin was up-regulated under both rhBMP-2 and HY-Dex-rhBMP-2 at Day 2, as also under 4 mg/ml HY, Dex, HY-Dex, Dex-rhBMP-2, and HY-Dex-rhBMP-2 by Day 7. Type 1alpha1 collagen was induced by rhBMP-2 on Day 2, and by Dex-rhBMP-2 on Day 7. Osteonectin and type X collagen was only marginally induced by HY at Day 2. Type 1alpha1 collagen and type X collagen were down-regulated in the presence of 4 mg/ml HY by Day 7. These results suggest that HY stimulates BMSc proliferation, osteocalcin gene expression, and a secretion of enzymes such as that of ALP activity in vitro. More importantly, HY can interact with Dex and rhBMP-2 to generate direct and specific cellular effects, which could be of major importance in bone tissue engineering.

Extracellular Matrix Changes in Stented Human Coronary Arteries

Background— Restenosis after stenting occurs secondary to the accumulation of smooth muscle cells (SMCs) and extracellular matrix (ECM), with the ECM accounting for >50% of the neointimal volume. The composition of the in-stent ECM has not been well characterized in humans.

Methods and Results— Postmortem human coronary arteries (n=45) containing stents underwent histological assessment of neointimal proteoglycans, hyaluronan, collagen (types I and III), SMCs, and CD44 (a cell surface receptor for hyaluronan). The mean duration of stent implantation was 18.7 months; stents in place ≥3 to <9 months (n=17) were assigned to group 1, stents ≥9 to <18 months old (n=19) to group 2, and stents ≥18 months old (n=9) to group 3. In groups 1 and 2, neointimal versican and hyaluronan staining was strongly positive, colocalized with α-actin-positive SMCs, and was greater in intensity compared with group 3. Conversely, decorin staining was greatest in group 3. The neointima of both group 1 and 2 stents was rich in type III collagen, with reduced staining in group 3. Type I collagen staining was weakest in group 1 stents, with progressively stronger staining in groups 2 and 3. SMC density and stent stenosis were significantly reduced in group 3 stents compared with groups 1 and 2. CD44 staining colocalized with macrophages and was associated with increased neointimal thickness.

Conclusions— The ECM within human coronary stents resembles a wound that is not fully healed until 18 months after deployment, followed by neointimal retraction. ECM contraction may be a target for therapies aimed at stent restenosis prevention.

Cell-matrix interaction via CD44 is independently regulated by different metalloproteinases activated in response to extracellular Ca(2+) influx and PKC activation

CD44 is an adhesion molecule that interacts with hyaluronic acid (HA) and undergoes sequential proteolytic cleavages in its ectodomain and intramembranous domain. The ectodomain cleavage is triggered by extracellular Ca(2+) influx or the activation of protein kinase C. Here we show that CD44-mediated cell-matrix adhesion is terminated by two independent ADAM family metalloproteinases, ADAM10 and ADAM17, differentially regulated in response to those stimuli. Ca(2+) influx activates ADAM10 by regulating the association between calmodulin and ADAM10, leading to CD44 ectodomain cleavage. Depletion of ADAM10 strongly inhibits the Ca(2+) influx-induced cell detachment from matrix. On the other hand, phorbol ester stimulation activates ADAM17 through the activation of PKC and small GTPase Rac, inducing proteolysis of CD44. Furthermore, depletion of ADAM10 or ADAM17 markedly suppressed CD44-dependent cancer cell migration on HA, but not on fibronectin. The spatio-temporal regulation of two independent signaling pathways for CD44 cleavage plays a crucial role in cell-matrix interaction and cell migration.

The role of hyaluronic acid in wound healing’s proliferative phase

This review discusses the multifaceted role of hyaluronic acid, focusing on the proliferative phase of wound healing. It considers the importance of achieving the right levels of this molecule, and the potential for future therapies.

Different heparan sulfate proteoglycans serve as cellular receptors for human papillomaviruses

Papillomaviruses replicate in stratified epithelia of skin and mucosa. Infection with certain human papillomavirus (HPV) types is the main cause of anogenital neoplasia, in particular cervical cancer. Early events of papillomavirus infectivity are poorly understood. While heparan sulfate proteoglycans (HSPGs) mediate initial binding to the cell surface, the class of proteins carrying heparan sulfates has not been defined. Here we examined two processes of papillomavirus infection, attachment of virus-like particles (VLP) to cells and infection with authentic HPV type 11 (HPV11) virions. Of the HSPGs, syndecan-1 is the major epithelial form and is strongly upregulated in wound edge keratinocytes. We employed K562 cells, which lack HSPGs except minor amounts of endogenous betaglycan, and stable clones that express cDNAs of syndecan-1, syndecan-4, or glypican-1. Binding of VLP correlated with levels of heparan sulfate on the cell surface. Parental K562 bound HPV16 VLP weakly, whereas all three K562 transfectants demonstrated enhanced binding, with the highest binding capacity observed for syndecan-1-transfected cells, which also expressed the most HSPG. For HPV11 infectivity assays, a high virion inoculum was required to infect K562 cells, whereas ectopic expression of syndecan-1 increased permissiveness eightfold and expression of syndecan-4 or glypican-1 fourfold. Infection of keratinocytes was eliminated by treatment with heparitinase, but not phospholipase C, further implicating the syndecan family of integral membrane proteins as receptor proteins. Human keratinocytes with a homozygous deletion of alpha6 integrin are permissive for HPV11 infection. These results indicate that several HSPGs can serve as HPV receptors and support a putative role for syndecan-1, rather than alpha6 integrin, as a primary receptor protein in natural HPV infection of keratinocytes.

Normal human keratinocytes bind to the alpha3LG4/5 domain of unprocessed laminin-5 through the receptor syndecan-1

Basal keratinocytes of the epidermis adhere to their underlying basement membrane through a specific interaction with laminin-5, which is composed by the association of alpha3, beta3, and gamma2 chains. Laminin-5 has the ability to induce either stable cell adhesion or migration depending on specific processing of different parts of the molecule. One event results in the cleavage of the carboxyl-terminal globular domains 4 and 5 (LG4/5) of the alpha3 chain. In this study, we recombinantly expressed the human alpha3LG4/5 fragment in mammalian cells, and we show that this fragment induces adhesion of normal human keratinocytes and fibrosarcoma-derived HT1080 cells in a heparan- and chondroitin sulfate-dependent manner. Immunoprecipitation experiments with Na2 35SO4-labeled keratinocyte and HT1080 cell lysates as well as immunoblotting experiments revealed that the major proteoglycan receptor for the alpha3LG4/5 fragment is syndecan-1. Syndecan-4 from keratinocytes also bound to alpha3LG4/5. Furthermore we could show for the first time that unprocessed laminin-5 specifically binds syndecan-1, while processed laminin-5 does not. These results demonstrate that the LG4/5 modules within unprocessed laminin-5 permit its cell binding activity through heparan and chondroitin sulfate chains of syndecan-1 and reinforce previous data suggesting specific properties for the precursor molecule.

Fibronectin and adhesion molecules on canine scarred vocal folds

OBJECTIVE

To examine the expressions of fibronectin and other adhesion molecules on the scarred vocal folds in a short- and long-term animal model.

STUDY DESIGN

Animal model.

METHODS

Six beagles' vocal folds were stripped unilaterally and left untreated. After wounding the vocal folds were harvested from three dogs at 2 months and three dogs at 6 months. The untouched vocal fold was used as a control, and the stripped vocal fold as scarred. Subsequently, the expressions of fibronectin, cadherin, syndecan-1 and syndecan-4 on both vocal folds were examined by immunohistochemical and image analysis.

RESULTS

Compared with the control vocal folds, fibronectin significantly increased in the superficial layer of the lamina propria on the scarred vocal folds at both 2 and 6 months. Co-deposition of collagen was observed only at 6 months. Syndecan-4 was significantly overexpressed at the basal layer cells of the epithelium at both 2 and 6 months. No significant expression of either cadherin or syndecan-1 was detected.

CONCLUSIONS

Scar characteristics at 2 and 6 months are not identical, suggesting that a 2-month period may not be a sufficient to study vocal fold scarring. Adhesion molecules are important in reorganization of extracellular matrix during wound healing because of their binding and adhesion characteristics. The results indicate that fibronectin might be important in providing a scaffold for the deposition of other proteins such as collagen, and the binding characteristics might affect the stiffness of the scarred vocal fold. Prolonged expression of syndecan-4 may reflect the role of focal adhesion during the assembly of scar structure. Ultimately, better understanding of the histological features of the scarred vocal fold might lead to new approaches to treatment.

Connective tissue responses in acute community-acquired pneumonia

Circulating connective tissue components including the aminoterminal propeptides of type III collagen (PIIINP), type I collagen (PINP) and hyaluronan were determined in patients hospitalised for pneumonia of suspected bacterial origin. Ninety patients were included, 64 of these were followed prospectively for up to 21 days after initiation of therapy. Serum PIIINP was determined by RIA, s-PINP by ELISA, and s-hyaluronan by a radiometric assay. S-PIIINP rose significantly above the zero value within 24 h in both pneumococcal pneumonia (T0: 5.3 microg/l, 95% CI: 2.7-8.1 microg/l vs. T1: 6.7 microg/l, 95% CI: 3.8-9.1, P<0.01) and in pneumonia of unknown aetiology (T0: 4.0 microg/l, 95% CI: 3.6-4.8 vs. T1: 4.5 microg/l, 95% CI: 3.8-5.1, P<0.05) followed by a gradual decline. At T1, S-PIIINP was higher in pneumococcal pneumonia compared with pneumonia of unknown aetiology (P<0.05). By contrast, s-PINP tended to decline within 24 h in both pneumococcal pneumonia (T1: 30 microg/l, 95% CI: 23-40, ns) and in pneumonia of unknown aetiology (T1: 32 microg/l, 95% CI: 22-42, ns) followed by a steady increase. The PINP antigen size distribution remained constant throughout the follow-up period. S-hyaluronan in pneumococcal pneumonia paralleled s-PIIINP reaching a peak value on day 1 (121 microg/l, 95% CI: 65-191, P=0.38). There was a positive correlation between s-PIIINP and C-reactive protein (CRP). The study demonstrates, that community-acquired pneumonia elicits a differentiated mesenchymal response, which is turned down in response to successful antibiotic therapy.

Different mechanisms of syndecan-1 activation through a fibroblast-growth-factor-inducible response element (FiRE) in mucosal and cutaneous wounds

Syndecan-1 expression is enhanced in cutaneous and mucosal wounds. We have previously demonstrated that wounding-induced syndecan-1 expression in the skin occurs transcriptionally, through a fibroblast-growth-factor-inducible element (FiRE). Here, we show that FiRE is also activated in mucosal wounds. However, both the expression patterns and the activation mechanisms of FiRE are different from those in the skin. In the mucosa in vivo, the activation starts and ends earlier than in cutaneous wounds. FiRE is first detected at around 12 hours in keratinocytes, and the activation declines by the third day after wounding occurs. The activation is seen on the migrating sheet of epithelial mucosa, as in the case of cutaneous wounding. In contrast to the situation in vivo, organ-cultured mucosal wounds exhibit no FiRE activity, while organ-cultured cutaneous wounds show robust activity. Activation in mucosal wounds is enhanced, however, by the application of epidermal growth factor. This suggests that exogenous growth factor activity is required for activation of syndecan-1 in mucosal wounds but not in cutaneous wounds.

Pathophysiology of intra-abdominal adhesion and abscess formation, and the effect of hyaluronan

BACKGROUND

Intra-abdominal adhesions and abscesses cause significant morbidity and mortality. The formation of fibrin in the abdominal cavity is a common pathophysiological pathway for both. The aim of this review was to investigate the pathophysiology of intra-abdominal adhesions and abscesses, and to explore the possible sites of action of hyaluronan.

METHODS

Data were reviewed from the literature using the Medline database.

RESULTS

Both surgery and peritonitis disturb the equilibrium between coagulation and fibrinolysis in the abdominal cavity in favour of the coagulation system. Hyaluronan-based agents reduce adhesion formation after surgery. Moreover, hyaluronan solution reduces abscess formation in experimental peritonitis. Possible mechanisms of action include mechanical separation of wound surfaces, improvement of peritoneal healing, modulation of the inflammatory response and enhanced fibrinolysis.

CONCLUSION

Diminished fibrin degradation is a common pathway for the formation of adhesions and abscesses. The potential of hyaluronan-based agents to reduce intra-abdominal adhesions and abscesses in abdominal surgery and sepsis is a promising new concept. Elucidating the mechanisms involved and the clinical application of hyaluronan in peritonitis are challenges for future research.

Comparison of the antioxidant properties of wound dressing materials--carboxymethylcellulose, hyaluronan benzyl ester and hyaluronan, towards polymorphonuclear leukocyte-derived reactive oxygen species

In chronic wounds, factors are released which perpetuate inflammatory processes, including polymorphonuclear leukocyte (PMN)-derived reactive oxygen species (ROS), such as superoxide radical (O(2)*-) and hydroxyl radical (*OH) species. The glycosaminoglycan, hyaluronan, has established antioxidant properties towards ROS, although the antioxidant potential of wound dressing biomaterials, such as 75% benzyl esterified hyaluronan (BEHA) and carboxymethylcellulose (CMCH), are less characterised. This study compared the antioxidant properties of high and low molecular weight hyaluronan (HMWT HA and LMWT HA), BEHA and CMCH towards ROS, generated by stimulated PMN in vitro. The antioxidant capacities of each biomaterial were assessed by their inhibition of O(2)*- -induced cytochrome C reduction, generated via PMN stimulation by phorbol myristyl acetate (PMA); and their inhibition of *OH-induced 2-deoxy-D-ribose degradation, generated by PMA stimulated PMN in the presence of a ferric chloride-EDTA chelate. All biomaterials, except LMWT HA, possessed dose-dependent antioxidant properties against O(2)*-, BEHA having greatest antioxidant potential, followed by HMWT HA and CMCH. HMWT HA exhibited the highest dose-dependent antioxidant properties towards *OH, followed by BEHA and CMCH. LMWT HA demonstrated no antioxidant properties towards *OH. These antioxidant activities, particularly towards O(2)*-, may be beneficial in removing the initial source of ROS necessary for the secondary formation of *OH, implicated as a causal factor for the extensive metabolic alterations observed in chronic wounds.

Keratinocyte motility induced by TGF-beta1 is accompanied by dramatic changes in cellular interactions with laminin 5

Transforming growth factor-beta1 (TGF-beta1) has the ability to induce epithelial cell migration while stopping proliferation. In this study, we show that, concomitant to promoting migration of normal human keratinocytes in vitro, TGF-beta1 induced a marked decrease in their adhesion capacity to processed alpha3-containing laminin 5-coated surfaces. Indeed, the expression levels of alpha3 and alpha6 integrin subunit mRNA and protein, as well as the cell surface alpha3beta1 and alpha6beta4 integrins, were down-regulated. Recent studies showed that keratinocytes over express and deposit laminin 5 during migration and we have shown that laminin 5 found in the matrix of TGF-beta1 induced migrating keratinocytes is present in its unprocessed form [Décline and Rousselle, 2001: J. Cell Sci. 114:811-823]. We show here that TGF-beta1 treatment of the cells promoted a significant increase in their adhesion to the alpha3 chain carboxy-terminal LG4/5 subdomain and that this interaction is likely to be mediated by a heparan sulfate proteoglycan type of receptor. Our results indicate that alpha6beta4 and alpha3beta1 integrin interactions with laminin 5 are diminished during migration while a specific interaction occurs between an additional cellular receptor and the alpha3 LG4/5 module present on unprocessed laminin 5.

Dermatan sulfate binds and potentiates activity of keratinocyte growth factor (FGF-7)

FGF-7 is induced after injury and induces the proliferation of keratinocytes. Like most members of the FGF family, the activity of FGF-7 is strongly influenced by binding to heparin, but this glycosaminoglycan is absent on keratinocyte cell surfaces and minimally present in the wound environment. In this investigation we compared the relative activity of heparan sulfate and chondroitin sulfate B (dermatan sulfate), glycosaminoglycans that are present in wounds. A lymphoid cell line (BaF/KGFR) containing the FGF-7 receptor (FGFR2 IIIb) was treated with FGF-7 and with various glycosaminoglycans. FGF-7 did not support cell proliferation in the absence of glycosaminoglycan or with addition of heparan sulfate or chondroitin sulfate A/C but did stimulate BaF/KGFR division in the presence of dermatan sulfate or highly sulfated low molecular weight fractions of dermatan. Dermatan sulfate also enabled FGF-7-dependent phosphorylation of mitogen-activated protein kinase and promoted binding of radiolabeled FGF-7 to FGFR2 IIIb. In addition, dermatan sulfate and FGF-7 stimulated growth of normal keratinocytes in culture. Thus, dermatan sulfate, the predominant glycosaminoglycan in skin, is the principle cofactor for FGF-7.

Changed lamellipodial extension, adhesion plaques and migration in epidermal keratinocytes containing constitutively expressed sense and antisense hyaluronan synthase 2 (Has2) genes

Hyaluronan is a major component of the epidermal extracellular matrix, is actively synthesized by keratinocytes and shows fast matrix turnover in the stratified epithelium. We probed the importance of hyaluronan synthesis in keratinocytes by establishing cell lines carrying the exogenous hyaluronan synthase 2 (Has2) gene in sense and antisense orientations to increase and decrease their hyaluronan synthesis, respectively. Compared with cell lines transfected with the vector only, most clones containing the Has2 sense gene migrated faster in an in vitro wounding assay, whereas Has2 antisense cells migrated more slowly. Has2 antisense clones showed delayed entry into the S phase of cell cycle following plating, smaller lamellipodia and less spreading on the substratum. The decrease of hyaluronan on the undersurface of Has2 antisense cells was associated with an increased area of adhesion plaques containing vinculin. Exogenous hyaluronan added to the keratinocyte cultures had a minor stimulatory effect on migration after wounding but did not restore the reduced migratory ability of Has2 antisense cells. Hyaluronan decasaccharides that displace receptor bound hyaluronan in keratinocytes, and Streptomyces hyaluronidase sufficient to remove most cell surface hyaluronan had little effect on cell migration. The results suggest that the dynamic synthesis of hyaluronan directed by Has2, rather than the abundance of pericellular hyaluronan, controls keratinocyte migration, a cell function vital for the repair of squamous epithelia following wounding.

Differential expression and distribution of syndecan-1 and -2 in periodontal wound healing of the rat

Cell-surface proteoglycans participate in several biological functions including interactions with adhesion molecules, growth factors and a variety of other effector molecules. Accordingly, these molecules play a central role in various aspects of cell-cell and cell-matrix interactions. To investigate the expression and distribution of the cell surface proteoglycans, syndecan-1 and -2, during periodontal wound healing, immunohistochemical analyses were carried out using monoclonal antibodies against syndecan-1, or -2 core proteins. Both syndecan-1 and -2 were expressed and distributed differentially at various stages of early inflammatory cell infiltration, granulation tissue formation, and tissue remodeling in periodontal wound healing. Expression of syndecan-1 was noted in inflammatory cells within and around the fibrin clots during the earliest stages of inflammatory cells infiltration. During granulation tissue formation it was noted in fibroblast-like cells and newly formed blood vessels. Syndecan-1 was not seen in newly formed bone or cementum matrix at any of the time periods studied. Syndecan-1 expression was generally less during the late stages of wound healing but was markedly expressed in cells that were close to the repairing junctional epithelium. In contrast, syndecan-2 expression and distribution was not evident at the early stages of inflammatory cell infiltration. During the formation of granulation tissue and subsequent tissue remodeling, syndecan-2 was expressed extracellularly in the newly formed fibrils which were oriented toward the root surface. Syndecan-2 was found to be significantly expressed on cells that were close to the root surface and within the matrix of repaired cementum covering root dentin as well as at the alveolar bone edge. These findings indicate that syndecan-1 and -2 may have distinctive functions during wound healing of the periodontium. The appearance of syndecan-1 may involve both cell-cell and cell-matrix interactions, while syndecan-2 showed a predilection to associate with cell-matrix interactions during hard tissue formation.

The cellular proliferative phase of the wound repair process

The proliferative--or new-tissue formation--phase of wound healing is complex. This article examines the changes that occur to cells during this stage and the effect on the extracellular matrix environment.

Comparison of the antioxidant properties of HYAFF-11p75, AQUACEL and hyaluronan towards reactive oxygen species in vitro

In chronic wounds, a number of host factors are released which perpetuate the inflammatory process, including polymorphonuclear leukocyte (PMN)-derived reactive oxygen species (ROS), such as superoxide radical (O2*-) and hydroxyl radical (*OH) species. The glycosaminoglycan. hyaluronan, has been shown to act as an antioxidant towards ROS, although the potential for biomaterials, such as HYAFF -11p75 (the 75% benzyl ester of hyaluronan) and AQUACEL (carboxymethylcellulose), to act in this manner has yet to be elucidated. This study compared the antioxidant properties of high and low molecular weight hyaluronan (HMWT HA and LMWT HA), HYAFF -11p75, AQUACEL and an AQUACEL /hyaluronan composite (AQUACEL /HA) against O2*- and *OH. The antioxidant capacities of each material were assessed by their ability to inhibit cytochrome C reduction by O2*- fluxes, generated via the oxidation of hypoxanthine by xanthine oxidase, and their inhibition of 2-deoxy-D-ribose degradation by *OH fluxes, generated by the reaction of hydrogen peroxide (H2O2) and iron (Fe2+). All materials studied possessed dose dependent antioxidant properties towards O2*-, with HYAFF 11p75 having the greatest antioxidant potential towards these species, followed by AQUACEL, HMWT HA, AQUACEL /HA and LMWT HA. Only HMWT HA exhibited dose dependent antioxidant properties towards *OH at the fluxes examined. Gas chromatography/mass spectrometry analysis implied that ester bonds between the hyaluronan backbone and benzyl groups of HYAFF -11p75 are highly susceptible to O2*- hydrolysis, with the de-esterified benzyl alcohol being rapidly degraded in the presence of *OH. This data supports the hypothesis that HYAFF -11p75 has greater antioxidant capacity towards O2*-, due to the esterified benzyl groups providing alternative sites for O2*- attack other than the hyaluronan backbone of HYAFF -11p75 itself and explains the inability of HYAFF -11p75 to scavenge *OH, due to benzyl alcohol degradation by *OH. The antioxidant activities of these biomaterials, particularly HYAFF -11p75 and AQUACEL, towards O2*- could be beneficial, as the scavenging of PMN-derived O2*- may remove initial sources of O2*- and further prevent the secondary formation of *OH. These ROS are thought to be a primary causal factor for the extensive degradation and metabolic alterations observed in chronic wounds.

Mechanical properties of single hyaluronan molecules

Hyaluronan (HA) is a major component of the extracellular matrix. It plays an important role in the mechanical functions of the extracellular matrix and stabilization of cells. Currently, its mechanical properties have been investigated only at the gross level. In this study, the mechanical properties of single HA molecules were directly measured with an optical tweezer technique, yielding a persistence length of 4.5 +/- 1.2 nm. This information may help us to understand the mechanical roles in the extracellular matrix infrastructure, cell attachment, and to design tissue engineering and drug delivery systems where the mechanical functions of HA are essential.

Anti-inflammatory and cicatrizing activity of Echinacea pallida Nutt. root extract

Among the different species belonging to the Echinacea family, largely used in traditional medicine, Echinacea pallida, Echinacea purpurea and Echinacea angustifolia were investigated. These different species, due to their difficult identification, were commonly confused in the past and probably used indifferently for the same therapeutic purposes. In fact, the three species have in common, some pharmacological activities, based on the presence of active compounds that act additively and synergistically. Nevertheless, the composition of each species has slight variation in the amount of each active component. In particular, echinacoside, a caffeoyl derivative, is present in E. pallida and only in traces in E. angustifolia. It seems to have protective effects on skin connective tissue and to enhance wound healing. The anti-inflammatory and wound healing activities of echinacoside, compared with the ones of the total root extract of E. pallida and E. angustifolia, were examined in rats, after topical application. The tissues of the treated animals were evaluated after 24, 48 and 72 h treatment and excised for histological observation at the end of the experiment. Results confirm the good anti-inflammatory and wound healing properties of E. pallida and of its constituent echinacoside, with respect to E. purpurea and control. This activity probably resides in the antihyaluronidase activity of echinacoside.

Expression in Escherichia coli, purification and kinetic characterization of human heparan sulfate 3-O-sulfotransferase-1

Heparan sulfate (HS) glycosaminoglycans are a structurally diverse class of complex biomolecules that modulate many important events at the cell surface and within the extracellular matrix and whose structural heterogeneity derives largely from the sequence-specific N- and O-sulfations catalyzed by an extensive repertoire of sulfating enzymes. We have expressed the human heparan sulfate 3-OST-1 isoform in Escherichia coli and subsequently purified a soluble, active enzyme. To assess its functionality, we determined the kinetic parameters for the recombinant 3-O-sulfotransferase-1 using a radiochemical assay that directly measures the 3-O-sulfation of unlabeled bovine kidney heparan sulfate in vitro using [(35)S]PAPS as the sulfate donor. The apparent K(m) values measured were in the low micromolar range (K(HS)(m) = 4.3 microM; K(PAPS)(m) = 38.6 microM); V(max) values of 18 and 21 pmol sulfate/min/pmol of enzyme for HS and PAPS, respectively. These values were compared with kinetic parameters likewise measured for recombinant 3-OST-1 purified from baculovirus-infected sf9 cells. The two enzymes appear to modify heparan sulfate in vitro to roughly the same extent and with comparable specificities. The expression of 3-OST-1 in E. coli represents an important step in subsequent structure-function studies.

Peptides that mimic glycosaminoglycans: high-affinity ligands for a hyaluronan binding domain

BACKGROUND

Hyaluronan (HA) is a non-sulfated glycosaminoglycan (GAG) that promotes motility, adhesion, and proliferation in mammalian cells, as mediated by cell-surface HA receptors. We sought to identify non-carbohydrate ligands that would bind to and activate cell-surface HA receptors. Such analogs could have important therapeutic uses in the treatment of cancer, wound healing, and arthritis, since such ligands would be resistant to degradation by hyaluronidase (HAse).

RESULTS

Peptide ligands that bind specifically to the recombinant HA binding domain (BD) of the receptor for hyaluronan-mediated motility (RHAMM) were obtained by screening two peptide libraries: (i) random 8-mers and (ii) biased 8-mers with alternating acidic side chains, i.e. XZXZXZXZ (X=all-L-amino acids except Cys, Lys, or Arg; Z=D-Asp, L-Asp, D-Glu, or L-Glu). Selectivity of the peptide ligands for the HABD was established by (i) detection of binding of biotin- or fluorescein-labeled peptides to immobilized proteins and (ii) fluorescence polarization of FITC-labeled peptides with the HABD in solution. HA competitively displaced binding of peptides to the HABD, while other GAGs were less effective competitors. The stereochemistry of four biased octapeptides was established by synthesis of the 16 stereoisomers of each peptide. Binding assays demonstrated a strong preference for alternating D and L configurations for the acidic residues, consistent with the calculated orientation of glucuronic acid moieties of HA.

CONCLUSIONS

Two classes of HAse-resistant peptide mimetics of HA were identified with high affinity, HA-compatible binding to the RHAMM HABD. This demonstrated that non-HA ligands specific to a given HA binding protein could be engineered, permitting receptor-specific targeting.

Up-regulation of putative hyaluronan synthase mRNA by basic fibroblast growth factor and insulin-like growth factor-1 in human skin fibroblasts

Recently, cDNAs for the three putative human hyaluronan synthase (HAS) genes, HAS1, HAS2 and HAS3, have been cloned. In this study we investigated the effects of basic fibroblast growth factor (bFGF) and insulin-like growth factor-1 (IGF-1) on the expression of HAS genes in cultured skin fibroblasts. Northern blot analyses showed that treatment of fibroblasts with bFGF enhanced the mRNA levels of all three genes. HAS2 gene expression showed the strongest up-regulation with a more than 10-fold increase at 50 ng/ml of bFGF. bFGF also increased hyaluronan production. Incubation of fibroblasts with IGF-1 increased HAS1, HAS2, and HAS3 mRNA levels, as well as hyaluronan production. Our results suggest that up-regulation of the HAS genes by bFGF and IGF-1 is closely associated with the stimulation of hyaluronan synthesis, and that effects of growth factors on HAS gene expression may have important implications for tissue remodeling, such as in development and wound healing.

Epidermal growth factor activates hyaluronan synthase 2 in epidermal keratinocytes and increases pericellular and intracellular hyaluronan

Hyaluronan is an abundant and rapidly turned over matrix molecule between the vital cell layers of the epidermis. In this study, epidermal growth factor (EGF) induced a coat of hyaluronan and a 3-5-fold increase in its rate of synthesis in a rat epidermal keratinocyte cell line that has retained its ability for differentiation. EGF also increased hyaluronan in perinuclear vesicles, suggesting concurrent enhancement in its endocytosis. Cell-associated hyaluronan was most abundant in elongated cells that were stimulated to migrate by EGF, as determined in vitro in a wound healing assay. Large fluctuations in the pool size of UDP-N-acetylglucosamine, the metabolic precursor of hyaluronan, correlated with medium glucose concentrations but not with EGF. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed no increase in hyaluronan synthases 1 and 3 (Has1 and Has3), whereas Has2 mRNA increased 2-3-fold in less than 2 h following the introduction of EGF, as estimated by quantitative RT-PCR with a truncated Has2 mRNA internal standard. The average level of Has2 mRNA increased from approximately 6 copies/cell in cultures before change of fresh medium, up to approximately 54 copies/cell after 6 h in EGF-containing medium. A control medium with 10% serum caused a maximum level of approximately 21 copies/cell at 6 h. The change in the Has2 mRNA levels and the stimulation of hyaluronan synthesis followed a similar temporal pattern, reaching a maximum level at 6 h and declining toward 24 h, a finding in line with a predominantly Has2-dependent hyaluronan synthesis and its transcriptional regulation.

Expression of CD44 and its isoforms in the fetal neuroblasts

CD44 is a polymorphic transmembrane glycoprotein that exists as multiple isoforms resulting from alternative splicing and posttranslational modifications. Enhanced expression of CD44 has been correlated to the tumorigenicity and metastatic behavior in different malignant tumors. In contrast, human neuroblastomas exhibit an inverse correlation between CD44 expression and tumor malignancy. To determine whether there is a CD44 silencing in sympatho-adrenal precursors as a possible explanation for the down-regulation of CD44 in neuroblastomas, the expression of standard CD44H and v6, v7, v7v8, or v10 isoforms was analyzed by immunohistochemistry in human adrenal glands of 14- to 20-week-old gestational age fetuses. All of the fetal neuroblasts localized in the adrenal gland parenchyma and migrating from the sympathetic nerve chain into the fetal adrenal cortex strongly expressed CD44H but none of the CD44 isoforms could be detected in these cells. In contrast, a strong expression of CD44v7 and v6 was detected in the fetal adrenal cells. These results indicate that, as for many other cell types, the CD44H expressed by fetal neuroblasts may contribute to controlling their migration into the adrenal medulla and that the down-regulation of CD44H in neuroblastoma cells should be explained by mechanisms other than the fetal suppression of CD44H expression in their normal counterparts.

Hyaluronic acid in incision wound fluid: a clinical study with the Cellstick device in children

When inserted into a human incision wound, the Cellstick device harvests inflammatory cells and collects wound fluid, reflecting time-related changes in cell populations and in wound fluid composition. Hyaluronic acid has been postulated to be an important factor in scar reduction in wound healing and in scarless fetal wound healing. The aim of this work was to determine the concentration and variation of hyaluronic acid and proportions of wound cells in closed surgical wounds in children at two time points. The Cellstick device was inserted subcutaneously into the wound at the end of an elective inguinal hernia operation on 37 healthy boys, and the devices were removed 3+/-1 or 24+/-3 hours after surgery. Haluronic acid concentration was measured from the wound fluid and a differential count of the wound cells was performed. There was a significant decrease in hyaluronic acid concentration from 3+/-1 to 24+/-3 hours after surgery (p<0.001, Kruskal-Wallis anova). The variance of hyaluronic acid concentration in wound fluid differed between the wounds at the two time points (p<0.01, Levene test for homogeneity of variance). A positive correlation between hyaluronic acid concentration and patient age (r=0.91, p<0.05, Spearman) at 3+/-1 hours post surgery and between HA and wound lymphocytes (r=0.38, p<0.05, Spearman) was also found. We conclude that the hyaluronic acid concentration in wound fluid peaks early in children and decreases significantly by 3 to 24 hours after surgery, and the concentrations in the wound fluid of healthy boys are more variable 3 hours than at 24 hours after surgery.

Enhancement of port site metastasis by hyaluronic acid under CO2 pneumoperitoneum in a murine model

BACKGROUND

The mechanism underlying the development and progression of port site metastasis after laparoscopic surgery for cancer is still not understood. Hyaluronic acid secreted from mesothelial cells is thought to be a key factor that causes adhesion between cancer cells and mesothelial cells. Using a murine model of carbon dioxide (CO2) pneumoperitoneum, we evaluated the effect of exogenous hyaluronic acid on port site metastasis.

METHODS

BALB/c mice were injected with 5 A- 106 human gastric carcinoma (MKN45) cells and divided into four groups treated with or without hyaluronic acid and with or without pneumoperitoneum. Three weeks later, the frequency and weight of port site metastases were determined. The effects of hyaluronic acid on tumorigenicity and tumor growth were examined in mice subcutaneously injected with MKN45 cells.

RESULTS

Port site metastasis occurred significantly less frequently in the pneumoperitoneum-only group than in the pneumoperitoneum-with-hyaluronic-acid group (75% vs 100%, p < 0.05). The port site metastatic tumor weighed significantly less in the control group (anesthesia only) than in the hyaluronic acid group (89 +/- 17 vs 288 +/- 35 mg, p < 0.05); it also weighed less in the pneumoperitoneum-only group than in the pneumoperitoneum-with-hyaluronic-acid group(87 +/- 24 vs 298 +/- 51 mg, p < 0.05). The frequency and weight of tumors in the subcutaneous tissue were not significantly different between groups with or without hyaluronic acid injection (95% vs 90%, 331 +/- 128 vs 322 +/- 115 mg).

CONCLUSIONS

Under CO2 pneumoperitoneum, exogenous hyaluronic acid increased the frequency and weight of port site metastasis in a murine model. Hyaluronic acid secreted from mesothelial cells may be associated with the formation of port site metastasis after laparoscopic surgery for cancer under pneumoperitoneum.

Immunohistochemical studies on proteoglycan expression in normal skin and chronic ulcers

BACKGROUND

Proteoglycans (PGs) represent a large family of complex molecules. They are found either as integral membrane components or constituents of the extracellular matrix. Their protein backbones are linked to different glycosaminoglycans, such as dermatan-, chondroitin-, keratan- or heparan sulphate. The molecules have specific functions during developmental processes as well as in diseases, such as cancer and inflammation.

OBJECTIVES

The expression patterns of various cell-associated heparan and chondroitin/dermatan-sulphate PGs in human skin and chronic venous ulcers were investigated.

METHODS

Tissue sections from 11 patients with chronic venous ulcers were used in this study. Monoclonal antibodies were used for detection of the proteoglycans syndecan-1, -2 and -4, glypican, CD44 and perlecan.

RESULTS

The different PGs exhibited individual staining patterns. Syndecan-1 and -4 and glypican expression in chronic ulcers differed from the staining in normal skin. Whereas the expression of syndecan-4 and glypican in intact skin was mostly in the pericellular regions of keratinocytes, the epidermal cells from the wound edge contained mostly intracellular PGs. In the wound edge, syndecan-4 was predominantly expressed by epidermal basal layer cells. Syndecan-1 was less expressed at the epidermal wound margins. PGs bind growth factors, regulate proteolytic activity and act as matrix receptors.

CONCLUSIONS

The altered expression patterns of glypican and syndecan-1 and -4 in chronic ulcers reflect their possible roles during inflammation and cell proliferation. Hence, analysis of PG expression should be of interest in future studies on normal as well as defective wound healing.

Hyaluronan enhances contraction of collagen by smooth muscle cells and adventitial fibroblasts: Role of CD44 and implications for constrictive remodeling

Remodeling contributes to restenosis when cells shrink the artery wall at sites of injury. This may be analogous to wound healing, where tissue remodeling achieves wound contraction. Hyaluronan (HA) is prominent in wound matrix and inhibits fetal scarring. HA is also produced in the artery wall after angioplasty, where it may inhibit constrictive remodeling. This hypothesis was tested in vitro using a model of matrix contraction. Primate aortic smooth muscle cells and adventitial fibroblasts were seeded into collagen I gels containing increasing amounts of HA (0% to 50%, wt/wt). Both cell types reduced the diameter of collagen alone approximately 65% at 18 hours. HA significantly increased gel contraction (diameter in mm: 0% HA, 7. 7+/-0.9; 2%, 7.1+/-0.7; 10%, 6.7+/-0.5; 50%, 5.6+/-0.9; P<0.05 for >/=10%), cell spreading and telopodia, and pericellular accumulation of collagen fibrils. These effects were mediated in part by cellular HA binding, because an antibody against CD44 receptors blocked pericellular collagen accumulation and enhanced gel contraction without altering cell shape. The role of CD44 was specific, because inhibiting receptor for hyaluronic acid-mediated motility (RHAMM) had no effect. Blocking ss(1)-integrins completely inhibited contraction of collagen, but gels containing HA required CD44 and ss(1)-integrin blockade for complete inhibition. Enhanced collagen reorganization and contraction were not attributable to increased collagenase activity, because the metalloproteinase inhibitor batimastat had no effect. In summary, HA enhanced collagen reorganization by the cell types most likely to mediate constrictive remodeling after angioplasty. These effects were CD44-dependent, thus providing a potential target for therapies to prevent constrictive remodeling and restenosis.

Hyaluronic acid secretion during carbon dioxide pneumoperitoneum and its association with port-site metastasis in a murine model

BACKGROUND

The mechanism of port-site metastasis after laparoscopic cancer surgery is unclear. This study aimed to determine whether carbon dioxide (CO2) pneumoperitoneum caused an increase in hyaluronic acid, which is secreted from mesothelial cells of the peritoneal cavity, and to assess the risk for port-site metastasis using a murine pneumoperitoneal model.

METHODS

Sandwich-binding protein assay was used to measure the concentration of hyaluronic acid in the peritoneal cavity at 6, 12, 18, 24, 48, and 72 h after CO2 pneumoperitoneum or laparotomy for 30 min. The concentrations of hyaluronic acid during pneumoperitoneum were compared among different gases (CO2, helium, air), intervals (5, 30, 60 min), and pressures (0-2, 4-6, 8-10 mmHg). To investigate the effects of exogenous hyaluronic acid, the development of port-site metastasis was examined using mouse adenocarcinoma cell-line colon 26 cells.

RESULTS

The intraperitoneal concentration of hyaluronic acid after CO2 pneumoperitoneum had increased already at 6 h, had reached the maximum level at 24 h, and had begun to decrease at 72 h. The concentration of hyaluronic acid at 24 h and 48 h in the CO2 pneumoperitoneum group was higher than that in the laparotomy group. This increase in hyaluronic acid also was found during helium and air pneumoperitoneum, and the concentration of hyaluronic acid in the peritoneal cavity was at its maximum when CO2 pneumoperitoneum lasted 30 min at 4 to 6 mmHg. The frequency of port-site metastasis was the highest when hyaluronic acid was injected during CO2 pneumoperitoneum (100%).

CONCLUSIONS

In a murine model, the intraperitoneal concentration of hyaluronic acid was significantly increased after CO2 pneumoperitoneum, and the increase was more evident than that after laparotomy. Increased hyaluronic acid during pneumoperitoneum may be associated with port-site metastasis after laparoscopic cancer surgery.

Proteoglycans and cutaneous vascular defense and repair

Proteoglycans are hybrid molecules composed of a core protein and covalently attached glycosaminoglycan chain(s). The structure, location, and processing of these molecules enables them to encode specific information that is used in multiple physiologic processes. Endothelial cells in the skin are influenced by proteoglycans through binding interactions between glycosaminoglycans and extracellular matrix, growth factors, cytokines, adhesion receptors, enzymes, and enzyme inhibitors. In wound repair, proteoglycans such as the syndecans are induced by antimicrobial peptides and can control growth factor responsiveness. The glycosaminoglycans further signal endothelial cells to increase expression of ICAM-1 and other molecules important for leukocyte adhesion. Thus, proteoglycans represent a powerful central regulatory element in skin that influences a wide variety of events and participates in host defense and tissue repair.