Modulation of TGFbeta1-dependent myofibroblast differentiation by hyaluronan

Hyaluronidase inhibits TGF-β-mediated rat periodontal ligament fibroblast expression of collagen and myofibroblast markers: An in vitro exploration of periodontal tissue remodeling

OBJECTIVE

To determine the effect of hyaluronic acid (HA) degradation by hyaluronidase (HYAL) in inhibiting collagen fiber production by rat periodontal ligament cells (rPDLCs).

DESIGN

Primary rPDLCs were isolated from the euthanized rats and used for in vitro experiments. The appropriate HYAL concentration was determined through CCK-8 testing for cytotoxicity detection and Alizarin red staining for mineralization detection. RT-qPCR and western blot assays were conducted to assess the effect of HYAL, with or without TGF-β, on generation of collagen fiber constituents and expression of actin alpha 2, smooth muscle (ACTA2) of rPDLCs.

RESULTS

Neither cell proliferation nor mineralization were significantly affected by treatment with 4 U/mL HYAL. HYAL (4 U/mL) alone downregulated type I collagen fiber (Col1a1 and Col1a2) and Acta2 mRNA expression; however, ACTA2 and COL1 protein levels were only downregulated by HYAL treatment after TGF-β induction.

CONCLUSIONS

Treatment of rPDLCs with HYAL can inhibit TGF-β-induced collagen matrix formation and myofibroblast transformation.

Alginate/hyaluronic acid-based systems as a new generation of wound dressings: A review

Skin is the largest organ of the human body, which acts as a protective barrier against pathogens. Therefore, a lot of research has been carried out on wound care and healing. Creating an ideal environment for wound healing and optimizing the local and systemic conditions of the patient play critical roles in successful wound care. Many products have been developed for improving the wound environment and providing a protected and moist area for fast healing. However, there is still high demand for new systems with high efficiency. The first generation of wound dressings merely covered the wound, while the subsequent/last generations covered it and aided in healing it in different ways. In modern wound dressings, the kind of used materials and their complexity play a crucial role in the healing process. These new systems support wound healing by lowering inflammation, exudate, slough, and bacteria. This study addresses a review of alginate/hyaluronic acid-based wound dressings developed so far as well as binary and ternary systems and their role in wound healing. Our review corroborates that these systems can open up a new horizon for wounds that do not respond to usual treatments and have a long curing period.

Basic and clinical study of the effect of exogenous hyaluronic acid on the quality of acellular dermal matrix combined with thin intermediate split thickness skin graft

BACKGROUND

To promote wound recovery in the recipient region, we studied the impact of exogenous hyaluronic acid (HA) on acellular dermal matrix (ADM) paired with thin intermediate-thickness skin transplant.

METHODS

This study contains animal and clinical experiments. 50 Japanese big ear rabbits were separated into HA1, HA2, PADM, TS, and NS groups. Clinical part included 50 scar patients dividing into 5 groups (TS + HA + ADM 1, TS + ADM2, TS, TS + ADM and normal skin (NS)).

RESULTS

In the animal trial, after 56 days, the grafts contracted least in the HA2 group; HA2 had the highest microvascular density (MVD), HA concentration, and collagen I and III expression. In clinical work, ADM > HA + ADM2 > HA + ADM1 > TS > NS; Type I and III collagen: HA + ADM1 and HA + ADM2 were higher than ADM; HA content: TS > HA + ADM1 > HA + ADM 2 > ADM.

CONCLUSIONS

ADM, exogenous hyaluronic acid mixed with thin skin autograft has better biomechanical qualities and therapeutic impact than acellular dermal matrix alone, and the reconstructive result is near to self-thick skin autograft in all indexes.

Hyaluronan synthesis inhibition normalizes ethanol-enhanced hepatic stellate cell activation

BACKGROUND

Chronic ethanol overconsumption promotes alcohol-associated liver disease (ALD), characterized by hepatocyte injury, inflammation, hepatic stellate cell (HSC) activation, and fibrosis. Hyaluronan (HA) concentration is greater in livers and blood from advanced ALD patients than patients with advanced non-ALD. In the liver, HSCs are the major HA producers. The relationship between ethanol, HA, and HSC activation is incompletely understood. Thus, here, we tested the hypothesis that ethanol enhances HSC activation in a HA-dependent manner.

METHODS

Liver tissue microarrays (TMAs) containing steatotic livers from donors with or without a history of alcohol consumption were used to measure HA and collagen content. Mice were fed a moderate (2%, v/v) ethanol-containing diet or pair-fed control diet for 2 days, after which they were given a single carbon tetrachloride (CCl4 ) injection. To inhibit HA synthesis, we provided 4-methylumbelliferone (4MU) daily. We used LX2 cells, a human HSC cell line, to determine the impact ethanol had on LPS responses, with or without concurrent 4MU exposure.

RESULTS

CCl4 induced liver injury, but it did not differ between ethanol or control diet fed mice with or without 4MU treatment. Ethanol feeding enhanced CCl4 -induced hepatic HA content, which was paralleled by HA synthase (Has)2 transcript abundance; 4MU treatment normalized both. Consistently, HSC activation, assessed by measuring αSMA mRNA and protein, was induced by CCl4 exposure, enhanced by ethanol feeding, and normalized by 4MU. Hepatic transcripts, but not protein, for Ccl2 were enhanced by ethanol feeding and normalized by 4MU exposure. Finally, ethanol-exposed LX2 cells made more LPS-stimulated CCL2 mRNA and protein than cells not exposed to ethanol; 4MU prevented this.

CONCLUSION

These data show that ethanol augments HSC activation through HA synthesis and enhances hepatic profibrogenic features. Therefore, targeting HSC HA production could potentially attenuate liver disease in ALD patients.

A systematic review of natural products for skin applications: Targeting inflammation, wound healing, and photo-aging

BACKGROUND

Every day the skin is constantly exposed to several harmful factors that induce oxidative stress. When the cells are incapable to maintain the balance between antioxidant defenses and reactive oxygen species, the skin no longer can keep its integrity and homeostasis. Chronic inflammation, premature skin aging, tissue damage, and immunosuppression are possible consequences induced by sustained exposure to environmental and endogenous reactive oxygen species. Skin immune and non-immune cells together with the microbiome are essential to efficiently trigger skin immune responses to stress. For this reason, an ever-increasing demand for novel molecules capable of modulating immune functions in the skin has risen the level of their development, particularly in the field of natural product-derived molecules.

PURPOSE

In this review, we explore different classes of molecules that showed evidence in modulate skin immune responses, as well as their target receptors and signaling pathways. Moreover, we describe the role of polyphenols, polysaccharides, fatty acids, peptides, and probiotics as possible treatments for skin conditions, including wound healing, infection, inflammation, allergies, and premature skin aging.

METHODS

Literature was searched, analyzed, and collected using databases, including PubMed, Science Direct, and Google Scholar. The search terms used included "Skin", "wound healing", "natural products", "skin microbiome", "immunomodulation", "anti-inflammatory", "antioxidant", "infection", "UV radiation", "polyphenols", "polysaccharides", "fatty acids", "plant oils", "peptides", "antimicrobial peptides", "probiotics", "atopic dermatitis", "psoriasis", "auto-immunity", "dry skin", "aging", etc., and several combinations of these keywords.

RESULTS

Natural products offer different solutions as possible treatments for several skin conditions. Significant antioxidant and anti-inflammatory activities were reported, followed by the ability to modulate immune functions in the skin. Several membrane-bound immune receptors in the skin recognize diverse types of natural-derived molecules, promoting different immune responses that can improve skin conditions.

CONCLUSION

Despite the increasing progress in drug discovery, several limiting factors need future clarification. Understanding the safety, biological activities, and precise mechanisms of action is a priority as well as the characterization of the active compounds responsible for that. This review provides directions for future studies in the development of new molecules with important pharmaceutical and cosmeceutical value.

A wound-friendly antibacterial hyaluronic acid dressing with on-demand removability for infected wound healing

BACKGROUND

Antibacterial activity and on-demand removability are key characteristics governing the effectiveness of clinic wound dressing. However, the excellent tissue adhesion of new dressings is often overemphasized without a detailed discussion of dressing replacement. Besides, the inherent antibacterial ability of dressings is beneficial for promoting the healing of infected wound. Therefore, we rationally design an injectable antibacterial wound dressing with on-demand removability to accelerate infected wound healing.

METHOD

We design this wound dressing with a simple and feasible method based on the electrostatic self-assembly of hyaluronic acid and ε-polylysine. We investigated the efficacy of this dressing in terms of its microtopography, rheology, self-healing performance, adhesive ability, antimicrobial, hemostatic, on-demand removal properties, and wound healing promotion through various tests.

RESULTS

The prepared dressing possesses injectability, self-healing ability and antibacterial activity, showing NaCl-triggered on-demand dissolution due to the disruption of electrostatic interactions. When used as dressings for healing full-thickness wounds, it could effectively accelerate wound healing by killing bacteria, downregulating inflammation, promoting collagen deposition, enhancing keratinocyte migration and angiogenesis due to its excellent adhesion ability, favorable hemostatic property, and potent antibacterial performance.

CONCLUSION

All results indicate that this is a simple and practical dressing for clinical application. This strategy provides a novel idea for developing on-demand removal dressings with antibacterial and injectable properties.

Extracellular-matrix-mimicked 3D nanofiber and hydrogel interpenetrated wound dressing with a dynamic autoimmune-derived healing regulation ability based on wound exudate

Dynamic regulation of wound physiological signals is the basis of wound healing. Conventional biomaterials delivering growth factors to drive wound healing leads to the passive repair of soft tissues because of the mismatch of wound healing stages. Meanwhile, the bioactivity of wound exudate is often restricted by oxidation and bacterial contamination. Herein, an extracellular matrix mimicked nanofiber/hydrogel interpenetrated network (NFHIN) was constructed with a 3D nanofibrous framework for cell immigration, and interfiled aerogel containing cross-linked hyaluronic acid and hyperbranched polyamidoamine to balance the wound microenvironment. The aerogel can collect wound exudate and transform into a polycationic hydrogel with contact-killing effects even against intracellular pathogens (bactericidal rate > 99.9% in 30 min) and real-time scavenging property of reactive oxygen species. After co-culturing with the NFHIN, the bioactivity of fibroblast in theex vivoblister fluid was improved by 389.69%. The NFHIN showed sustainable exudate management with moisture-vapor transferring rate (6000 g m^-2×24 h), equilibrium liquid content (75.3%), Young's modulus (115.1 ± 7 kPa), and anti-tearing behavior similar to human skin. The NFHIN can collect and activate wound exudate, turning it from a clinical problem to an autoimmune-derived wound regulation system, showing potential for wound care in critical skin diseases.

Transforming Growth Factor-β Receptor-Mediated, p38 Mitogen-Activated Protein Kinase-Dependent Signaling Drives Enhanced Myofibroblast Differentiation during Skin Wound Healing in Mice Lacking Hyaluronan Synthases 1 and 3

Normal myofibroblast differentiation is critical for proper skin wound healing. Neoexpression of α-smooth muscle actin (α-SMA), a marker for myofibroblast differentiation, is driven by transforming growth factor (TGF)-β receptor-mediated signaling. Hyaluronan and its three synthesizing enzymes, hyaluronan synthases (Has 1, 2, and 3), also participate in this process. Closure of skin wounds is significantly accelerated in Has1/3 double-knockout (Has1/3-null) mice. Herein, TGF-β activity and dermal collagen maturation were increased in Has1/3-null healing skin. Cultures of primary skin fibroblasts isolated from Has1/3-null mice had higher levels of TGF-β activity, α-SMA expression, and phosphorylation of p38 mitogen-activated protein kinase at Thr180/Tyr182, compared with wild-type fibroblasts. p38α mitogen-activated protein kinase was a necessary element in a noncanonical TGF-β receptor signaling pathway driving α-SMA expression in Has1/3-null fibroblasts. Myocardin-related transcription factor (MRTF), a cofactor that binds to the transcription factor serum response factor (SRF), was also critical. Nuclear localization of MRTF was increased, and MRTF binding to SRF was enhanced in Has1/3-null fibroblasts. Inhibition of MRTF or SRF expression by RNA interference suppresses α-SMA expression at baseline and diminished its overexpression in Has1/3-null fibroblasts. Interestingly, total matrix metalloproteinase activity was increased in healing skin and fibroblasts from Has1/3-null mice, possibly explaining the increased TGF-β activation.

Bridging a Century-Old Problem: The Pathophysiology and Molecular Mechanisms of HA Filler-Induced Vascular Occlusion (FIVO)—Implications for Therapeutic Interventions

Biocompatible hyaluronic acid (HA, hyaluronan) gel implants have altered the therapeutic landscape of surgery and medicine, fostering an array of innovative products that include viscosurgical aids, synovial supplements, and drug-eluting nanomaterials. However, it is perhaps the explosive growth in the cosmetic applications of injectable dermal fillers that has captured the brightest spotlight, emerging as the dominant modality in plastic surgery and aesthetic medicine. The popularity surge with which injectable HA fillers have risen to in vogue status has also brought a concomitant increase in the incidence of once-rare iatrogenic vaso-occlusive injuries ranging from disfiguring facial skin necrosis to disabling neuro-ophthalmological sequelae. As our understanding of the pathophysiology of these injuries has evolved, supplemented by more than a century of astute observations, the formulation of novel therapeutic and preventative strategies has permitted the amelioration of this burdensome complication. In this special issue article, we review the relevant mechanisms underlying HA filler-induced vascular occlusion (FIVO), with particular emphasis on the rheo-mechanical aspects of vascular blockade; the thromboembolic potential of HA mixtures; and the tissue-specific ischemic susceptibility of microvascular networks, which leads to underperfusion, hypoxia, and ultimate injury. In addition, recent therapeutic advances and novel considerations on the prevention and management of muco-cutaneous and neuro-ophthalmological complications are examined.

The Pro-fibrotic Response of Mesenchymal Leader Cells to Lens Wounding Involves Hyaluronic Acid, Its Receptor RHAMM, and Vimentin

Hyaluronic Acid/Hyaluronan (HA) is a major component of the provisional matrix deposited by cells post-wounding with roles both in regulating cell migration to repair a wound and in promoting a fibrotic outcome to wounding. Both are mediated through its receptors CD44 and RHAMM. We now showed that HA is present in the provisional matrix assembled on the substrate surface in a lens post-cataract surgery explant wound model in which mesenchymal leader cells populate the wound edges to direct migration of the lens epithelium across the adjacent culture substrate onto which this matrix is assembled. Inhibiting HA expression with 4-MU blocked assembly of FN-EDA and collagen I by the wound-responsive mesenchymal leader cells and their migration. These cells express both the HA receptors CD44 and RHAMM. CD44 co-localized with HA at their cell-cell interfaces. RHAMM was predominant in the lamellipodial protrusions extended by the mesenchymal cells at the leading edge, and along HA fibrils organized on the substrate surface. Within a few days post-lens wounding the leader cells are induced to transition to αSMA+ myofibroblasts. Since HA/RHAMM is implicated in both cell migration and inducing fibrosis we examined the impact of blocking HA synthesis on myofibroblast emergence and discovered that it was dependent on HA. While RHAMM has not been previously linked to the intermediate filament protein vimentin, our studies with these explant cultures have shown that vimentin in the cells’ lamellipodial protrusions regulate their transition to myofibroblast. PLA studies now revealed that RHAMM was complexed with both HA and vimentin in the lamellipodial protrusions of leader cells, implicating this HA/RHAMM/vimentin complex in the regulation of leader cell function post-wounding, both in promoting cell migration and in the transition of these cells to myofibroblasts. These results increase our understanding of how the post-wounding matrix environment interacts with receptor/cytoskeletal complexes to determine whether injury outcomes are regenerative or fibrotic.

Injectable multifunctional CMC/HA-DA hydrogel for repairing skin injury

Injectable Hydrogels with adhesive, antioxidant and hemostatic properties are highly desired for promoting skin injury repair. In this study, we prepared a multi-functional carboxymethyl chitosan/hyaluronic acid-dopamine (CMC/HA-DA) hydrogel, which can be crosslinked by horseradish peroxidase and hydrogen peroxide. The antioxidation, gelation time, degradability, rheology and antihemorrhagic properties of hydrogels can be finely tuned by varying composition ratio. The cytocompatibility test and hemolysis test confirmed that the designed hydrogel holds good biocompatibility. More importantly, the repair effect of the hydrogel on full-thickness skin injury model in mice was studied. The results of wound healing, collagen deposition, immunohistochemistry and immunofluorescence showed that CMC/HA-DA hydrogel could significantly promote angiogenesis and cell proliferation at the injured site. Notably, the inflammatory response can also be regulated to promote the repair of full-thickness skin defect in mice. Results indicate that this injectable CMC/HA-DA hydrogel holds high application prospect for promising wound healing.

New Therapeutic Approach for Intestinal Fibrosis Through Inhibition of pH-Sensing Receptor GPR4

BACKGROUND

Patients suffering from inflammatory bowel diseases (IBDs) express increased mucosal levels of pH-sensing receptors compared with non-IBD controls. Acidification leads to angiogenesis and extracellular matrix remodeling. We aimed to determine the expression of pH-sensing G protein-coupled receptor 4 (GPR4) in fibrotic lesions in Crohn's disease (CD) patients. We further evaluated the effect of deficiency in Gpr4 or its pharmacologic inhibition.

METHODS

Paired samples from fibrotic and nonfibrotic terminal ileum were obtained from CD patients undergoing ileocaecal resection. The effects of Gpr4 deficiency were assessed in the spontaneous Il-10-/- and the chronic dextran sodium sulfate (DSS) murine colitis model. The effects of Gpr4 deficiency and a GPR4 antagonist (39c) were assessed in the heterotopic intestinal transplantation model.

RESULTS

In human terminal ileum, increased expression of fibrosis markers was accompanied by an increase in GPR4 expression. A positive correlation between the expression of procollagens and GPR4 was observed. In murine disease models, Gpr4 deficiency was associated with a decrease in angiogenesis and fibrogenesis evidenced by decreased vessel length and expression of Edn, Vegfα, and procollagens. The heterotopic animal model for intestinal fibrosis, transplanted with terminal ileum from Gpr4-/- mice, revealed a decrease in mRNA expression of fibrosis markers and a decrease in collagen content and layer thickness compared with grafts from wild type mice. The GPR4 antagonist decreased collagen deposition. The GPR4 expression was also observed in human and murine intestinal fibroblasts. The GPR4 inhibition reduced markers of fibroblast activation stimulated by low pH, notably Acta2 and cTgf.

CONCLUSIONS

Expression of GPR4 positively correlates with the expression of profibrotic genes and collagen. Deficiency of Gpr4 is associated with a decrease in angiogenesis and fibrogenesis. The GPR4 antagonist decreases collagen deposition. Targeting GPR4 with specific inhibitors may constitute a new treatment option for IBD-associated fibrosis.

Mechanical Loading Disrupts Focal Adhesion Kinase Activation in Mandibular Fibrochondrocytes During Murine Temporomandibular Joint Osteoarthritis

PURPOSE

Mechanical overloading is a key initiating condition for temporomandibular joint (TMJ) osteoarthritis (OA). The integrin-focal adhesion kinase (FAK) signaling axis is implicated in the mechanobiological response of cells through phosphorylation at Tyr397 (pFAK) but poorly defined in TMJ health and disease. We hypothesize that mechanical overloading disrupts TMJ homeostasis through dysregulation of FAK signaling.

MATERIALS AND METHODS

To assess if FAK and pFAK are viable clinical targets for TMJ OA, peri-articular tissues were collected from patients with TMJ OA receiving a total TMJ replacement. To compare clinical samples with preclinical in vivo studies of TMJ OA, the joints of c57/bl6 mice were surgically destabilized and treated with and without inhibitor of pFAK (iFAK). FAK signaling and TMJ OA progression was evaluated and compared using RT-PCR, western blot, immunohistochemistry, and histomorphometry. To evaluate mechanical overloading in vitro, primary murine mandibular fibrochondrocytes were seeded in a 4% agarose-collagen scaffold and loaded in a compression bioreactor with and without iFAK.

RESULTS

FAK/pFAK was mostly absent from the articular cartilage layer in the clinical sample and suppressed on the central condyle and elevated on the lateral and medial condyle in murine TMJ OA. In vitro, compressive loading lowered FAK/pFAK levels and elevated the expression of TGFβ, NG2, and MMP-13. iFAK treatment suppressed MMP13 and Col6 and elevated TGFβ, NG2, and ACAN in a load independent manner. In vivo, iFAK treatment moderately attenuated OA progression and increased collagen maturation.

CONCLUSION

These data illustrate that FAK/pFAK is implicated in the signaled dysfunction of excessive mechanical loading during TMJ OA and that iFAK treatment can moderately attenuate the progression of cartilage degeneration in the mandibular condyle.

Myofibroblasts: Function, Formation, and Scope of Molecular Therapies for Skin Fibrosis

Myofibroblasts are contractile, α-smooth muscle actin-positive cells with multiple roles in pathophysiological processes. Myofibroblasts mediate wound contractions, but their persistent presence in tissues is central to driving fibrosis, making them attractive cell targets for the development of therapeutic treatments. However, due to shared cellular markers with several other phenotypes, the specific targeting of myofibroblasts has long presented a scientific and clinical challenge. In recent years, myofibroblasts have drawn much attention among scientific research communities from multiple disciplines and specialisations. As further research uncovers the characterisations of myofibroblast formation, function, and regulation, the realisation of novel interventional routes for myofibroblasts within pathologies has emerged. The research community is approaching the means to finally target these cells, to prevent fibrosis, accelerate scarless wound healing, and attenuate associated disease-processes in clinical settings. This comprehensive review article describes the myofibroblast cell phenotype, their origins, and their diverse physiological and pathological functionality. Special attention has been given to mechanisms and molecular pathways governing myofibroblast differentiation, and updates in molecular interventions.

Hyaluronan, Transforming Growth Factor β, and Extra Domain A-Fibronectin: A Fibrotic Triad

Significance: Inflammation is a critical aspect of injury repair. Nonresolving inflammation, however, is perpetuated by the local generation of extracellular matrix-derived damage-associated molecular pattern molecules (DAMPs), such as the extra domain A (EDA) isoform of fibronectin and hyaluronic acid (HA) that promote the eventual acquisition of a fibrotic response. DAMPs contribute to the inflammatory environment by engaging Toll-like, integrin, and CD44 receptors while stimulating transforming growth factor (TGF)-β signaling to activate a fibroinflammatory genomic program leading to the development of chronic disease. Recent Advances: Signaling through TLR4, CD44, and the TGF-β pathways impact the amplitude and duration of the innate immune response to endogenous DAMPs synthesized in the context of tissue injury. New evidence indicates that crosstalk among these three networks regulates phase transitions as well as the repertoire of expressed genes in the wound healing program determining, thereby, repair outcomes. Clarifying the molecular mechanisms underlying pathway integration is necessary for the development of novel therapeutics to address the spectrum of fibroproliferative diseases that result from maladaptive tissue repair. Critical Issues: There is an increasing appreciation for the role of DAMPs as causative factors in human fibroinflammatory disease regardless of organ site. Defining the involved intermediates essential for the development of targeted therapies is a daunting effort, however, since various classes of DAMPs activate different direct and indirect signaling pathways. Cooperation between two matrix-derived DAMPs, HA, and the EDA isoform of fibronectin, is discussed in this review as is their synergy with the TGF-β network. This information may identify nodes of signal intersection amenable to therapeutic intervention. Future Directions: Clarifying mechanisms underlying the DAMP/growth factor signaling nexus may provide opportunities to engineer the fibroinflammatory response to injury and, thereby, wound healing outcomes. The identification of shared and unique DAMP/growth factor-activated pathways is critical to the design of optimized tissue repair therapies while preserving the host response to bacterial pathogens.

A Role for HAPLN1 During Phenotypic Modulation of Human Lung Fibroblasts In Vitro

Hyaluronan and proteoglycan link protein 1 (HAPLN1) stabilizes interactions between two important extracellular matrix (ECM) macromolecules, versican and hyaluronan, which facilitate proliferation of fibroblasts and their conversion to myofibroblasts. However, the role of HAPLN1 in these events has not been studied. Using immunocytochemistry, cellular and ECM locations of HAPLN1 were evaluated in cultured human lung fibroblasts during proliferation and conversion to myofibroblasts. HAPLN1 localized to pericellular matrices, associating with both versican and hyaluronan in the ECM and on the cell surface. Nuclear and total HAPLN1 immunostaining increased after myofibroblast induction. Confocal microscopy showed HAPLN1 predominant in the ECM under cells while versican predominated above cells. Versican and HAPLN1 were also juxtaposed in columnar inclusions in the cytoplasm and nucleus. Nuclear HAPLN1 staining in interphase cells redistributed to the cytosol during mitosis. In the absence of TGF-β1, addition of exogenous bovine HAPLN1 (together with aggrecan G1) facilitated myofibroblast formation, as seen by significant upregulation of α-smooth muscle actin (SMA) staining, while adding full-length bovine versican had no effect. Increased compaction of hyaluronan-rich ECM suggests that HAPLN1 plus G1 addition affects hyaluronan networks and myofibroblast formation. These observations demonstrate changes in both extracellular and intracellular localization of HAPLN1 during fibroblast proliferation and myofibroblast conversion suggesting a possible role in fibrotic remodeling.

Multifunctional Natural Polymer Nanoparticles as Antifibrotic Gene Carriers for CKD Therapy

BACKGROUND

Progressive fibrosis is the underlying pathophysiological process of CKD, and targeted prevention or reversal of the profibrotic cell phenotype is an important goal in developing therapeutics for CKD. Nanoparticles offer new ways to deliver antifibrotic therapies to damaged tissues and resident cells to limit manifestation of the profibrotic phenotype.

METHODS

We focused on delivering plasmid DNA expressing bone morphogenetic protein 7 (BMP7) or hepatocyte growth factor (HGF)-NK1 (HGF/NK1) by encapsulation within chitosan nanoparticles coated with hyaluronan, to safely administer multifunctional nanoparticles containing the plasmid DNA to the kidneys for localized and sustained expression of antifibrotic factors. We characterized and evaluated nanoparticles in vitro for biocompatibility and antifibrotic function. To assess antifibrotic activity in vivo, we used noninvasive delivery to unilateral ureteral obstruction mouse models of CKD.

RESULTS

Synthesis of hyaluronan-coated chitosan nanoparticles containing plasmid DNA expressing either BMP7 or NGF/NKI resulted in consistently sized nanoparticles, which-following endocytosis driven by CD44⁺ cells-promoted cellular growth and inhibited fibrotic gene expression in vitro. Intravenous tail injection of these nanoparticles resulted in approximately 40%-45% of gene uptake in kidneys in vivo. The nanoparticles attenuated the development of fibrosis and rescued renal function in unilateral ureteral obstruction mouse models of CKD. Gene delivery of BMP7 reversed the progression of fibrosis and regenerated tubules, whereas delivery of HGF/NK1 halted CKD progression by eliminating collagen fiber deposition.

CONCLUSIONS

Nanoparticle delivery of HGF/NK1 conveyed potent antifibrotic and proregenerative effects. Overall, this research provided the proof of concept on which to base future investigations for enhanced targeting and transfection of therapeutic genes to kidney tissues, and an avenue toward treatment of CKD.

Myofibroblasts and Fibrosis: Mitochondrial and Metabolic Control of Cellular Differentiation

Cardiac fibrosis is mediated by the activation of resident cardiac fibroblasts, which differentiate into myofibroblasts in response to injury or stress. Although myofibroblast formation is a physiological response to acute injury, such as myocardial infarction, myofibroblast persistence, as occurs in heart failure, contributes to maladaptive remodeling and progressive functional decline. Although traditional pathways of activation, such as TGFβ (transforming growth factor β) and AngII (angiotensin II), have been well characterized, less understood are the alterations in mitochondrial function and cellular metabolism that are necessary to initiate and sustain myofibroblast formation and function. In this review, we highlight recent reports detailing the mitochondrial and metabolic mechanisms that contribute to myofibroblast differentiation, persistence, and function with the hope of identifying novel therapeutic targets to treat, and potentially reverse, tissue organ fibrosis.

Hyaluronic acid-Based wound dressings: A review

Hyaluronic acid (HA), a non-sulfated glycosaminoglycan (GAG), is a major component of skin extracellular matrix (ECM) and it is involved in the inflammatory response, angiogenesis, and tissue regeneration process. Due to the intrinsic properties of HA (such as biocompatibility, biodegradability and hydrophilic character), it has been used to produce different wound dressings, namely sponges, films, hydrogels, and electrospun membranes. Herein, an overview of the different HA-based wound dressings that have been produced so far is provided as well as the future directions regarding the strategies aimed to improve the mechanical stability of HA-based wound dressings, along with the incorporation of biomolecules intended to ameliorate their biological performance during the healing process.

Hyaluronidase-2 Regulates RhoA Signaling, Myofibroblast Contractility, and Other Key Profibrotic Myofibroblast Functions

Hyaluronidase (HYAL)-2 is a weak, acid-active, hyaluronan-degrading enzyme broadly expressed in somatic tissues. Aberrant HYAL2 expression is implicated in diverse pathology. However, a significant proportion of HYAL2 is enzymatically inactive; thus the mechanisms through which HYAL2 dysregulation influences pathobiology are unclear. Recently, nonenzymatic HYAL2 functions have been described, and nuclear HYAL2 has been shown to influence mRNA splicing to prevent myofibroblast differentiation. Myofibroblasts drive fibrosis, thereby promoting progressive tissue damage and leading to multimorbidity. This study identifies a novel HYAL2 cytoplasmic function in myofibroblasts that is unrelated to its enzymatic activity. In fibroblasts and myofibroblasts, HYAL2 interacts with the GTPase-signaling small molecule ras homolog family member A (RhoA). Transforming growth factor beta 1–driven fibroblast-to-myofibroblast differentiation promotes HYAL2 cytoplasmic relocalization to bind to the actin cytoskeleton. Cytoskeletal-bound HYAL2 functions as a key regulator of downstream RhoA signaling and influences profibrotic myofibroblast functions, including myosin light-chain kinase–mediated myofibroblast contractility, myofibroblast migration, myofibroblast collagen/fibronectin deposition, as well as connective tissue growth factor and matrix metalloproteinase-2 expression. These data demonstrate that, in certain biological contexts, the nonenzymatic effects of HYAL2 are crucial in orchestrating RhoA signaling and downstream pathways that are important for full profibrotic myofibroblast functionality. In conjunction with previous data demonstrating the influence of HYAL2 on RNA splicing, these findings begin to explain the broad biological effects of HYAL2.

Elastic, Persistently Moisture-Retentive, and Wearable Biomimetic Film Inspired by Fetal Scarless Repair for Promoting Skin Wound Healing

An efficient and available material for promoting skin regeneration is of great importance for public health, but it remains an elusive goal. Inspired by fetal scarless wound healing, we develop a wearable biomimetic film (WBMF) composed of hyaluronan (HA), vitamin E (VE), dopamine (DA), and β-cyclodextrin (β-CD) that mimics the fetal context (FC) and fetal extracellular matrix (ECM) around the wound bed for dermal regeneration. First, the WBMF creates the FC of sterility, hypoxia, persistent moisture, and no secondary insults for wounds as the result of its seamless adhesion to the skin, optimum stress-stretch and high-cycle fatigue resistance matching the anisotropic tension of the skin, and water-triggered self-healing behavior. Thus, the WBMF modulates the early wound situation to minimize inflammatory response. In the meantime, the WBMF mimics the critical biological function of fetal ECM, inducing fibroblast migration, suppressing the overexpression of transforming growth factor β1, and mediating collagen synthesis, distribution, and reestablishment. As a result, the WBMF accelerates wound healing and gains a normal dermal collagen architecture, thereby restoring scarless appearance. Overall, the WBMF provides a new paradigm for promoting skin wound healing and may find broad utility for the field of regenerative medicine.

Hypoxia and transforming growth factor β1 regulation of long non-coding RNA transcriptomes in human pulmonary fibroblasts

One of the key characteristics of idiopathic pulmonary fibrosis (IPF) is accumulation of excess fibrous tissue in the lung, which leads to hypoxic conditions. Transforming growth factor (TGF) β is a major mediator that promotes the differentiation of fibroblasts to myofibroblasts. However, how hypoxia and TGFβ together contribute the pathogenesis of IPF is poorly understood. Long non-coding RNAs (lncRNAs) have regulatory effects on certain genes and are involved in many diseases. In this study, we determined the effects of hypoxia and/or TGFβ on mRNA and lncRNA transcriptomes in pulmonary fibroblasts. Hypoxia and TGFβ1 synergistically increased myofibroblast marker expression. RNA sequencing revealed that hypoxia and TGFβ1 treatment resulted in significant changes in 669 lncRNAs and 2,676 mRNAs compared to 150 lncRNAs and 858 mRNAs in TGFβ1 alone group and 222 lncRNAs and 785 mRNAs in hypoxia alone group. TGFβ1 induced the protein expression of HIF-1α, but not HIF-2α. On the other hand, hypoxia enhanced the TGFβ1-induced phosphorylation of Smad3, suggesting a cross-talk between these two signaling pathways. In all, 10 selected lncRNAs (five-up and five-down) in RNA sequencing data were validated using real-time PCR. Two lncRNAs were primarily located in cytoplasm, three in nuclei and five in both nuclei and cytoplasm. The silencing of HIF-1α and Smad3, but not Smad2 and HIF-2α rescued the downregulation of FENDRR by hypoxia and TGFβ1. In conclusion, hypoxia and TGFβ1 synergistically regulate mRNAs and lncRNAs involved in several cellular processes, which may contribute to the pathogenesis of IPF.

CD44 inhibits α-SMA gene expression via a novel G-actin/MRTF-mediated pathway that intersects with TGFβR/p38MAPK signaling in murine skin fibroblasts

Well-regulated differentiation of fibroblasts into myofibroblasts (MF) is critical for skin wound healing. Neoexpression of α-smooth muscle actin (α-SMA), an established marker for MF differentiation, is driven by TGFβ receptor (TGFβR)-mediated signaling. Hyaluronan (HA) and its receptor CD44 may also participate in this process. To further understand this process, primary mouse skin fibroblasts were isolated and treated in vitro with recombinant TGF-β1 (rTGF-β1) to induce α-SMA expression. CD44 expression was also increased. Paradoxically, CD44 knockdown by RNA interference (RNAi) led to increased α-SMA expression and α-SMA-containing stress fibers. Removal of extracellular HA or inhibition of HA synthesis had no effect on α-SMA levels, suggesting a dispensable role for HA. Exploration of mechanisms linking CD44 knockdown to α-SMA induction, using RNAi and chemical inhibitors, revealed a requirement for noncanonical TGFβR signaling through p38MAPK. Decreased monomeric G-actin but increased filamentous F-actin following CD44 RNAi suggested a possible role for myocardin-related transcription factor (MRTF), a known regulator of α-SMA transcription and itself regulated by G-actin binding. CD44 RNAi promoted nuclear accumulation of MRTF and the binding to its transcriptional cofactor SRF. MRTF knockdown abrogated the increased α-SMA expression caused by CD44 RNAi, suggesting that MRTF is required for CD44-mediated regulation of α-SMA. Finally, chemical inhibition of p38MAPK reversed nuclear MRTF accumulation after rTGF-β1 addition or CD44 RNAi, revealing a central involvement of p38MAPK in both cases. We concluded that CD44 regulates α-SMA gene expression through cooperation between two intersecting signaling pathways, one mediated by G-actin/MRTF and the other via TGFβR/p38MAPK.

Tumor-secreted extracellular vesicles promote the activation of cancer-associated fibroblasts via the transfer of microRNA-125b

Tumour cells release large quantities of extracellular vesicles (EVs) to mediate their interactions with other cells in the tumour microenvironment. To identify host cells that naturally take up EVs from tumour cells, we created breast cancer cell lines secreting fluorescent EVs. These fluorescent EVs are taken up most robustly by fibroblasts within the tumour microenvironment. RNA sequencing indicated that miR-125b is one of the most abundant microRNAs secreted by mouse triple-negative breast cancer 4T1 and 4TO7 cells. Treatment with 4T1 EVs leads to an increase in fibroblast activation in isogenic 4TO7 tumours, which is reversed by blocking miR-125b in 4T1 EVs; hence, miR-125b delivery by EVs is responsible for fibroblast activation in mouse tumour models. miR-125b is also secreted by human breast cancer cells and the uptake of EVs from these cells significantly increases cellular levels of miR-125b and expression of multiple cancer-associated fibroblast markers in resident fibroblasts. Overexpression of miR-125b in both mouse and human fibroblasts leads to an activated phenotype similar to the knockdown of established miR-125b target mRNAs. These data indicate that miR-125b is transferred through EVs from breast cancer cells to normal fibroblasts within the tumour microenvironment and contributes to their development into cancer-associated fibroblasts.

The extracellular matrix as a multitasking player in disease

Extracellular matrices (ECMs) are highly specialized and dynamic three-dimensional (3D) scaffolds into which cells reside in tissues. ECM is composed of a variety of fibrillar components, such as collagens, fibronectin, and elastin, and non-fibrillar molecules as proteoglycans, hyaluronan, and glycoproteins including matricellular proteins. These macromolecular components are interconnected forming complex networks that actively communicate with cells through binding to cell surface receptors and/or matrix effectors. ECMs exert diverse roles, either providing tissues with structural integrity and mechanical properties essential for tissue functions or regulating cell phenotype and functions to maintain tissue homeostasis. ECM molecular composition and structure vary among tissues, and is markedly modified during normal tissue repair as well as during the progression of various diseases. Actually, abnormal ECM remodeling occurring in pathologic circumstances drives disease progression by regulating cell-matrix interactions. The importance of matrix molecules to normal tissue functions is also highlighted by mutations in matrix genes that give rise to genetic disorders with diverse clinical phenotypes. In this review, we present critical and emerging issues related to matrix assembly in tissues and the multitasking roles for ECM in diseases such as osteoarthritis, fibrosis, cancer, and genetic diseases. The mechanisms underlying the various matrix-based diseases are also discussed. Research focused on the highly dynamic 3D ECM networks will help to discover matrix-related causative abnormalities of diseases as well as novel diagnostic tools and therapeutic targets.

HIV-1 Protein gp120 Induces Mouse Lung Fibroblast-to-Myofibroblast Transdifferentiation via CXCR4 Activation

BACKGROUND

Individuals with HIV have ∼2-fold increased risk of developing pulmonary fibrosis. The mechanism(s) by which this occurs has yet to be determined. HIV-1 protein gp120 activates CXCR4 in the lymphocyte, promoting a variety of intracellular signaling pathways including those common to TGFβ1 associated with lung fibroblast-to-myofibroblast transdifferentiation. We hypothesized that gp120 promotes pulmonary fibrotic changes via activation of CXCR4 in the lung fibroblast.

METHODS

Mouse primary lung fibroblasts (PLFs) were cultured ± gp120, then analyzed for α-SMA expression and stress fiber formation. In parallel, PLFs were cultured ± gp120 ± AMD3100 (a CXCR4 antagonist), and α-SMA, pan and phospho-Akt, and total and phospho-MAPK (or ERK1/2) protein expression was quantified. Finally, lungs and PLFs from wild-type and HIV-1 transgenic mice were analyzed for hydroxyproline and α-SMA content.

RESULTS

gp120 treatment increased α-SMA expression and myofibroblast differentiation in PLFs. gp120 treatment activated phosphorylation of ERK1/2, but not PI3K-Akt. Pretreatment with AMD3100 inhibited gp120-induced ERK1/2 phosphorylation and gp120-induced α-SMA expression. In parallel, there was a significant increase in hydroxyproline content in lungs from older HIV-1 transgenic mice and a >3-fold increase in α-SMA expression in PLFs isolated from HIV-1 transgenic mice.

CONCLUSIONS

gp120 induces α-SMA expression and fibroblast-to-myofibroblast transdifferentiation by activating the CXCR4-ERK1/2 signaling pathway in mouse PLFs. Lungs of older HIV-1 transgenic mice contain higher hydroxyproline content and their PLFs have a striking increase in α-SMA expression. These results suggest a mechanism by which individuals with HIV are at increased risk of developing pulmonary fibrotic changes as they age.

Two-photon fluorescence and second harmonic generation characterization of extracellular matrix remodeling in post-injury murine temporomandibular joint osteoarthritis

End stage temporomandibular joint osteoarthritis (TMJ-OA) is characterized by fibrillations, fissures, clefts, and erosion of the mandibular condylar cartilage. The goal of this study was to define changes in pericellular and interterritorial delineations of the extracellular matrix (ECM) that occur preceding and concurrent with the development of this end stage degeneration in a murine surgical instability model. Two-photon fluorescence (TPF) and second harmonic generation (SHG) microscopy was used to evaluate TMJ-OA mediated changes in the ECM. We illustrate that TPF/SHG microscopy reconstructs the three-dimensional network of key fibrillar and micro-fibrillar collagens altered during the progression of TMJ-OA. This method not only generates spatially distinct pericellular and interterritorial delineations of the ECM but distinguishes early and end stage TMJ-OA by signal organization, orientation, and composition. Early stage TMJ-OA at 4- and 8-weeks post-injury is characterized by two structurally distinct regions containing dense, large fiber collagens and superficial, small fiber collagens rich in types I, III, and VI collagen oriented along the mesiodistal axis of the condyle. At 8-weeks post-injury, type VI collagen is locally diminished on the central and medial condyle, but the type I/III rich superficial layer is still present. Twelve- and 16-weeks post-injury mandibular cartilage is characteristic of end-stage disease, with hypocellularity and fibrillations, fissures, and clefts in the articular layer that propagate along the mediolateral axis of the MCC. We hypothesize that the localized depletion of interterritorial and pericellular type VI collagen may signify an early marker for the transition from early to end stage TMJ-OA, influence the injury response of the tissue, and underlie patterns of degeneration that follow attritional modes of failure.

Hyaluronan and Its Interactions With Immune Cells in the Healthy and Inflamed Lung

Hyaluronan is a hygroscopic glycosaminoglycan that contributes to both extracellular and pericellular matrices. While the production of hyaluronan is essential for mammalian development, less is known about its interaction and function with immune cells. Here we review what is known about hyaluronan in the lung and how it impacts immune cells, both at homeostasis and during lung inflammation and fibrosis. In the healthy lung, alveolar macrophages provide the first line of defense and play important roles in immunosurveillance and lipid surfactant homeostasis. Alveolar macrophages are surrounded by a coat of hyaluronan that is bound by CD44, a major hyaluronan receptor on immune cells, and this interaction contributes to their survival and the maintenance of normal alveolar macrophage numbers. Alveolar macrophages are conditioned by the alveolar environment to be immunosuppressive, and can phagocytose particulates without alerting an immune response. However, during acute lung infection or injury, an inflammatory immune response is triggered. Hyaluronan levels in the lung are rapidly increased and peak with maximum leukocyte infiltration, suggesting a role for hyaluronan in facilitating leukocyte access to the injury site. Hyaluronan can also be bound by hyaladherins (hyaluronan binding proteins), which create a provisional matrix to facilitate tissue repair. During the subsequent remodeling process hyaluronan concentrations decline and levels return to baseline as homeostasis is restored. In chronic lung diseases, the inflammatory and/or repair phases persist, leading to sustained high levels of hyaluronan, accumulation of associated immune cells and an inability to resolve the inflammatory response.

Signaling Mechanisms of Myofibroblastic Activation: Outside-in and Inside-Out

Myofibroblasts are central mediators of fibrosis. Typically derived from resident fibroblasts, myofibroblasts represent a heterogeneous population of cells that are principally defined by acquired contractile function and high synthetic ability to produce extracellular matrix (ECM). Current literature sheds new light on the critical role of ECM signaling coupled with mechanotransduction in driving myofibroblastic activation. In particular, transforming growth factor β1 (TGF-β1) and extra domain A containing fibronectin (EDA-FN) are thought to be the primary ECM signaling mediators that form and also induce positive feedback loops. The outside-in and inside-out signaling circuits are transmitted and integrated by TGF-β receptors and integrins at the cell membrane, ultimately perpetuating the abundance and activities of TGF-β1 and EDA-FN in the ECM. In this review, we highlight these conceptual advances in understanding myofibroblastic activation, in hope of revealing its therapeutic anti-fibrotic implications.

Insights into the key roles of epigenetics in matrix macromolecules-associated wound healing

Extracellular matrix (ECM) is a dynamic network of macromolecules, playing a regulatory role in cell functions, tissue regeneration and remodeling. Wound healing is a tissue repair process necessary for the maintenance of the functionality of tissues and organs. This highly orchestrated process is divided into four temporally overlapping phases, including hemostasis, inflammation, proliferation and tissue remodeling. The dynamic interplay between ECM and resident cells exerts its critical role in many aspects of wound healing, including cell proliferation, migration, differentiation, survival, matrix degradation and biosynthesis. Several epigenetic regulatory factors, such as the endogenous non-coding microRNAs (miRNAs), are the drivers of the wound healing response. microRNAs have pivotal roles in regulating ECM composition during wound healing and dermal regeneration. Their expression is associated with the distinct phases of wound healing and they serve as target biomarkers and targets for systematic regulation of wound repair. In this article we critically present the importance of epigenetics with particular emphasis on miRNAs regulating ECM components (i.e. glycoproteins, proteoglycans and matrix proteases) that are key players in wound healing. The clinical relevance of miRNA targeting as well as the delivery strategies designed for clinical applications are also presented and discussed.

Versican A-subdomain is required for its adequate function in dermal development

Versican, a large chondroitin sulfate (CS) proteoglycan, serves as a structural macromolecule of the extracellular matrix (ECM) and regulates cell behavior. We determined the function of versican in dermal development using Vcan^Δ3/Δ3 mutant mice expressing versican with deleted A-subdomain of the N-terminal G1 domain. The mutant versican showed a decreased hyaluronan (HA)-binding ability and failed to accumulate in the ECM. In the early developmental stage, Vcan^Δ3/Δ3 dermis showed a decrease in versican expression as compared with WT. As development proceeded, versican expression further decreased to a barely detectable level, and Vcan^Δ3/Δ3 mice died at the neonatal period (P0). At P0, Vcan^Δ3/Δ3 dermis exhibited an impaired ECM structure and decreased cell density. While the level of collagen deposition was similar in both genotypes, collagen biosynthesis significantly decreased in Vcan^Δ3/Δ3 fibroblasts as compared with that in wild type (WT). Transforming growth factor β (TGFβ) signaling mediated through the Smad2/3-dependent pathway was down-regulated in Vcan^Δ3/Δ3 fibroblasts and a reduced TGFβ storage in the ECM was observed. Microarray analysis revealed a decrease in the expression levels of transcription factors, early growth response (Egr) 2 and 4, which act downstream of TGFβ signaling. Thus, our results suggest that A-subdomain is necessary for adequate versican expression in dermis and that versican is involved in the formation of the ECM and regulation of TGFβ signaling.

[Influence of TGF-β cytokine and a number of other biochemical factors on regenerative process]

Scarring is one of the main causes of surgical failure in a number of eye diseases, dacryologic conditions in particular. The process of wound healing, including postoperative wound healing, goes through several stages mediated by various biochemical factors, such as growth factors and pro- and anti-inflammatory cytokines. The balance between the latter directly influences the wound healing. However, current data on the effect of these factors on postoperative outcomes are few and contradictory. Thus, in dacryology as well as in other areas of ophthalmology, the role of cytokines and growth factors in healing of surgical wounds is being intensively researched.

Provisional matrix: A role for versican and hyaluronan

Hyaluronan and versican are extracellular matrix (ECM) components that are enriched in the provisional matrices that form during the early stages of development and disease. These two molecules interact to create pericellular "coats" and "open space" that facilitate cell sorting, proliferation, migration, and survival. Such complexes also impact the recruitment of leukocytes during development and in the early stages of disease. Once thought to be inert components of the ECM that help hold cells together, it is now quite clear that they play important roles in controlling cell phenotype, shaping tissue response to injury and maintaining tissue homeostasis. Conversion of hyaluronan-/versican-enriched provisional matrix to collagen-rich matrix is a "hallmark" of tissue fibrosis. Targeting the hyaluronan and versican content of provisional matrices in a variety of diseases including, cardiovascular disease and cancer, is becoming an attractive strategy for intervention.

The relationship between plasma hyaluronan levels and anthracycline-related cardiotoxicity in breast cancer patients

AIM

Anthracycline-derived antineoplastic agents are used as the main form of treatment in many malignant diseases, including breast cancer and childhood cancers. Cardiotoxicity is one of the most feared life-threatening complications of cancer therapy. In the present study, we aimed to investigate the relationship between plasma hyaluronan (HA) levels and anthracycline-induced cardiotoxicity.

MATERIALS AND METHODS

Fifty eight of 73 female patients who were diagnosed with breast cancer and treated with a chemotherapy regimen including anthracycline were enrolled in this study. Anamneses were taken from each patient before and after chemotherapy. Further, physical examinations, electrocardiography, and transthoracic echocardiography were performed, and plasma hyaluronan levels were determined by using ELISA assay for each patient before and after treatment.

RESULTS

Following anthracycline-based chemotherapy, the average left ventricular ejection fraction decreased (62.6±3.7% vs. 58.6±4.4%, p<0.001), and diastolic functions significantly deteriorated (p<0.001). However, troponin and hyaluronan levels significantly increased following chemotherapy [Troponin (ng/ml, mean±SD): before 0.01±0.002, after 0.037±0.02, p<0.001], [Plasma HA (ng/ml, mean±SD): before 41.3±5.4, after 70±8.5, p<0.001]. The increase in troponin values correlated with systolic dysfunction (p=0.002), but did not correlate with diastolic dysfunction (p=0.661). Significant correlations were found between systolic/diastolic dysfunction and plasma HA levels (r=0.417, p=0.001; r=0.339, p=0.009, respectively).

CONCLUSIONS

Both systolic and diastolic functions were significantly deteriorated after chemotherapy. In addition, plasma levels of HA and troponin increased after treatment. Further, both systolic and diastolic dysfunctions were found to correlate with serum HA levels. All these data suggest that HA might have a function on anthracycline-induced cardiotoxicity.

4-Methylumbelliferone Diminishes Catabolically Activated Articular Chondrocytes and Cartilage Explants via a Mechanism Independent of Hyaluronan Inhibition

Depletion of the cartilage proteoglycan aggrecan is one of the earliest events that occurs in association with osteoarthritis. This loss is often accompanied by a coordinate loss in another glycosaminoglycan, hyaluronan. Chondrocytes experimentally depleted of cell-associated hyaluronan respond by switching to a pro-catabolic metabolism that includes enhanced production of endogenous inflammatory mediators and increased synthesis of matrix metalloproteinases. Hyaluronan turnover is also increased. Together, such a response provides for possible establishment of a self-perpetuating spiral of events that maintains or prolongs the pro-catabolic state. Chondrocytes or cartilage can also be activated by treatment with pro-inflammatory cytokines and mediators such as IL-1β, TNFα, LPS, fibronectin fragments, and hyaluronan oligosaccharides. To determine the mechanism of chondrocyte activation due to hyaluronan loss, a depletion method was required that did not include degrading the hyaluronan. In recent years, several laboratories have used the coumarin derivative, 4-methylumbelliferone, as a potent inhibitor of hyaluronan biosynthesis, due in part to its ability to sequester intracellular UDP-glucuronic acid and inhibition of hyaluronan synthase transcription. However, contrary to our expectation, although 4-methylumbelliferone was indeed an inhibitor of hyaluronan biosynthesis, this depletion did not give rise to an activation of chondrocytes or cartilage. Rather, 4-methylumbelliferone directly and selectively blocked gene products associated with the pro-catabolic metabolic state of chondrocytes and did so through a mechanism preceding and independent of hyaluronan inhibition. These data suggest that 4-methylumbelliferone has additional useful applications to block pro-inflammatory cell activation events but complicates how it is used for defining functions related to hyaluronan.

Hyaluronan: More than just a wrinkle filler

Dermatology is a field that strives not only to alleviate skin disease (therapeutics) but also to improve the perception of wellness (cosmetics). Thus, in this special issue of Glycobiology, it seems appropriate to discuss the biology of a glycosaminoglycan, called hyaluronic acid (hyaluronan, or HA), that has become the most popular agent today for intradermal injections to improve wrinkles and other cosmetic defects. HA is a simple linear polymer in which a simple disaccharide is repeated thousands of time, thereby creating a huge hydrophilic molecule that confers a large volume of hydration and contributes to the turgor and flexibility of healthy skin. Beyond cosmetic considerations, however, HA also has important biological and physiological functions that were largely under-appreciated until recently. New research has confirmed that HA is dynamically produced by most skin cells, not only fibroblasts (the cells that make most of the skin's extracellular matrix) but also by keratinocytes in the outer protective layer (epidermis). For both fibroblasts and keratinocytes, HA plays a regulatory role in controlling cell physiology through interaction of extracellular HA with a major cell-surface receptor, CD44. This interaction mediates intracellular signaling both directly and indirectly, through CD44 interactions with the cytoskeleton and with EGF and TGFβ receptors. Furthermore, degradation of HA by specific hyaluronidase enzymes produces HA fragments that can help to regulate inflammatory processes. In this review, current knowledge about the role of HA in skin inflammation and wound healing are reviewed and possible future applications of such knowledge discussed.

Extracellular Matrix and Dermal Fibroblast Function in the Healing Wound

Significance: Fibroblasts play a critical role in normal wound healing. Various extracellular matrix (ECM) components, including collagens, fibrin, fibronectin, proteoglycans, glycosaminoglycans, and matricellular proteins, can be considered potent protagonists of fibroblast survival, migration, and metabolism. Recent Advances: Advances in tissue culture, tissue engineering, and ex vivo models have made the examination and precise measurements of ECM components in wound healing possible. Likewise, the development of specific transgenic animal models has created the opportunity to characterize the role of various ECM molecules in healing wounds. In addition, the recent characterization of new ECM molecules, including matricellular proteins, dermatopontin, and FACIT collagens (Fibril-Associated Collagens with Interrupted Triple helices), further demonstrates our cursory knowledge of the ECM in coordinated wound healing. Critical Issues: The manipulation and augmentation of ECM components in the healing wound is emerging in patient care, as demonstrated by the use of acellular dermal matrices, tissue scaffolds, and wound dressings or topical products bearing ECM proteins such as collagen, hyaluronan (HA), or elastin. Once thought of as neutral structural proteins, these molecules are now known to directly influence many aspects of cellular wound healing. Future Directions: The role that ECM molecules, such as CCN2, osteopontin, and secreted protein, acidic and rich in cysteine, play in signaling homing of fibroblast progenitor cells to sites of injury invites future research as we continue investigating the heterotopic origin of certain populations of fibroblasts in a healing wound. Likewise, research into differently sized fragments of the same polymeric ECM molecule is warranted as we learn that fragments of molecules such as HA and tenascin-C can have opposing effects on dermal fibroblasts.

Hyaluronan as a therapeutic target in human diseases

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

Master regulators in primary skin fibroblast fate reprogramming in a human ex vivo model of chronic wounds

Fibroblasts are important players in regulating tissue homeostasis. In the dermis, they are involved in wound healing where they differentiate into contractile myofibroblasts leading to wound closure. In nonhealing chronic wounds, fibroblasts fail to undertake differentiation. We established and used a human ex vivo model of chronic wounds where fibroblasts can undergo normal myofibroblast differentiation, or take on a nondifferentiable pathological state. At the whole genome scale, we identified the genes that are differentially regulated in these two cell fates. By coupling the search of evolutionary conserved regulatory elements with global gene network expression changes, we identified transcription factors (TF) potentially involved in myofibroblast differentiation, and constructed a network of relationship between these key factors. Among these, we found that TCF4, SOX9, EGR2, and FOXS1 are major regulators of fibroblast to myofibroblast differentiation. Conversely, down-regulation of MEOX2, SIX2, and MAF causes reprogramming of fibroblasts to myofibroblasts even in absence of TGF-β, the natural inducer of myofibroblast differentiation. These results provide insight into the fibroblast differentiation program and reveal a TF network essential for cellular reprogramming. They could lead to the development of new therapeutics to treat fibroblast-related human pathologies.

Esophageal Squamous Cell Carcinoma Cells Modulate Chemokine Expression and Hyaluronan Synthesis in Fibroblasts

The aim of this study was to characterize the interaction of KYSE-410, an esophageal squamous cell carcinoma cell line, and fibroblasts with respect to the extracellular matrix component hyaluronan (HA) and chemokine expression. KYSE-410 cells induced the mRNA expression of HA synthase 2 (Has2) in normal skin fibroblasts (SF) only in direct co-cultures. Parallel to Has2 mRNA, Has2 antisense RNA (Has2os2) was up-regulated in co-cultures. Knockdown of LEF1, a downstream target of Wnt signaling, abrogated Has2 and Has2os2 induction. After knockdown of Has2 in SF, significantly less α-smooth muscle actin expression was detected in co-cultures. Moreover, it was investigated whether the phenotype of KYSE-410 was affected in co-culture with SF and whether Has2 knockdown in SF had an impact on KYSE-410 cells in co-culture. However, no effects on epithelial-mesenchymal transition markers, proliferation, and migration were detected. In addition to Has2 mRNA, the chemokine CCL5 was up-regulated and CCL11 was down-regulated in SF in co-culture. Furthermore, co-cultures of KYSE-410 cells and cancer-associated fibroblasts (CAF) were investigated. Similar to SF, Has2 and Ccl5 were up-regulated and Ccl11 was down-regulated in CAF in co-culture. Importantly and in contrast to SF, inhibiting HA synthesis by 4-methylumbelliferone abrogated the effect of co-culture on Ccl5 in CAF. Moreover, HA was found to promote adhesion of CD4(+) but not CD8(+) cells to xenogaft tumor tissues. In conclusion, direct co-culture of esophageal squamous cell carcinoma and fibroblasts induced stromal HA synthesis via Wnt/LEF1 and altered the chemokine profile of stromal fibroblasts, which in turn may affect the tumor immune response.

Hyperglycemia-Induced Changes in Hyaluronan Contribute to Impaired Skin Wound Healing in Diabetes: Review and Perspective

Ulcers and chronic wounds are a particularly common problem in diabetics and are associated with hyperglycemia. In this targeted review, we summarize evidence suggesting that defective wound healing in diabetics is causally linked, at least in part, to hyperglycemia-induced changes in the status of hyaluronan (HA) that resides in the pericellular coat (glycocalyx) of endothelial cells of small cutaneous blood vessels. Potential mechanisms through which exposure to high glucose levels causes a loss of the glycocalyx on the endothelium and accelerates the recruitment of leukocytes, creating a proinflammatory environment, are discussed in detail. Hyperglycemia also affects other cells in the immediate perivascular area, including pericytes and smooth muscle cells, through exposure to increased cytokine levels and through glucose elevations in the interstitial fluid. Possible roles of newly recognized, cross-linked forms of HA, and interactions of a major HA receptor (CD44) with cytokine/growth factor receptors during hyperglycemia, are also discussed.

Myofibroblasts

Myofibroblasts are activated in response to tissue injury with the primary task to repair lost or damaged extracellular matrix. Enhanced collagen secretion and subsequent contraction - scarring - are part of the normal wound healing response and crucial to restore tissue integrity. Due to myofibroblasts ability to repair but not regenerate, accumulation of scar tissue is always associated with reduced organ performance. This is a fair price to pay by the body for not falling apart. Whereas myofibroblasts typically vanish after successful repair, dysregulation of the normal repair process can lead to persistent myofibroblast activation, for instance by chronic inflammation or mechanical stress in the tissue. Excessive repair leads to the accumulation of stiff collagenous ECM contractures - fibrosis - with dramatic consequences for organ function. The clinical need to terminate detrimental myofibroblast activities has stimulated researchers to answer a number of essential questions: where do myofibroblasts come from, what are the factors leading to their activation, how do we discriminate myofibroblasts from other cells, what is the molecular basis for their contractile activity, and how can we stop or at least control them? This article reviews the current state of the myofibroblast literature by emphasizing their role in ocular repair and fibrosis. It appears that although the eye is quite an extraordinary organ, ocular myofibroblasts behave or misbehave just like their siblings in other organs.

Unravelling osteoarthritis-related synovial fibrosis: a step closer to solving joint stiffness

Synovial fibrosis is often found in OA, contributing heavily to joint pain and joint stiffness, the main symptoms of OA. At this moment the underlying mechanism of OA-related synovial fibrosis is not known and there is no cure available. In this review we discuss factors that have been reported to be involved in synovial fibrosis. The aim of the study was to gain insight into how these factors contribute to the fibrotic process and to determine the best targets for therapy in synovial fibrosis. In this regard, the following factors are discussed: TGF-β, connective tissue growth factor, procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2, tissue inhibitor of metalloproteinase 1, A disintegrin and metalloproteinase domain 12, urotensin-II, prostaglandin F2α and hyaluronan.

Hyaluronan in wound healing: rediscovering a major player

Wound healing involves a series of carefully modulated steps, from initial injury and blood clot to the final reconstituted tissue or scar. A dynamic reciprocity exists throughout between the wound, blood elements, extracellular matrix, and cells that participate in healing. Multiple cytokines and signal transduction pathways regulate these reactions. A major component throughout most of the process is hyaluronan, a straight-chain carbohydrate extracellular matrix polymer. Hyaluronan occurs in multiple forms, chain length being the only distinguishing characteristic between them. Levels of hyaluronan in its high-molecular-weight form are prominent in the earliest stages of wound repair. Progressively more fragmented forms occur in a manner not previously appreciated. We outline here steps in the wound healing cascade in which hyaluronan participates, as well as providing a review of its metabolism. Although described by necessity in a series of quantum steps, the healing process is constituted by a smooth continuum of overlapping reactions. The prevalence of hyaluronan in the wound (initially termed "hexosamine-containing mucopolysaccharide"), particularly in its early stages, was pointed out over half a century ago by the Harvard surgeon J. Engelbert Dunphy. It appears we are now returning to where we started.