Distribution of hyaluronan during extracellular matrix remodeling in human restenotic arteries and balloon-injured rat carotid arteries

Mixture Containing 5% Polysaccharide Extract of Cerioporus squamosus (Huds.) Quélet, 5% Dexpanthenol, and 0.2% Hyaluronic Acid Shows In Vitro and In Vivo Wound Healing Properties

Background: This study explores wound healing and the antimicrobial potential of a natural formulation containing a polysaccharide extract from Cerioporus squamosus, hyaluronic acid, and dexpanthenol. Methods: Wound healing effects were assessed using HaCaT keratinocytes, while antimicrobial activity was evaluated against human skin pathogens using a microdilution assay. In vitro cytotoxicity tests ensured formulation safety, whereas in vivo wound healing was further investigated using an animal model. Gene expression analysis was performed to assess the molecular mechanisms involved. Results: The unique glucan composition of C. squamosus (15.38% α-glucans and 7.91% β-glucans) deviated from typical mushroom polysaccharide profiles, warranting further exploration of its bioactivity. In vitro mushroom polysaccharides promoted 25.35% wound closure after 24 hours, while the three-component formulation achieved 35.81% closure. Antibacterial activity showed a minimum inhibitory concentration (MIC) of 0.44-1.75 mg/mL and minimum bactericidal concentration (MBCs) of 0.88-3.50 mg/mL, while antifungal activity ranged from 0.22 to 0.44 mg/mL (MICs) and 0.44 to 0.88 mg/mL (minimum fungicidal concentration-MFC). In vivo data showed that 60% of treated wounds fully closed by day 11, despite no statistically significant difference from the control. However, gene expression analysis highlighted VEGF and collagen upregulation, indicating an enhancement of wound healing on a molecular level. Conclusions: The novel three-component formulation demonstrated consistent wound healing and antimicrobial properties, supporting its potential as a safe and effective treatment for chronic and acute wounds.

Wound Healing Complications After Sternotomy-Causes, Prevention, and Treatment-A New Look at an Old Problem

Median sternotomy is one of the most common procedures in cardiac surgery. This corresponds to the relatively high frequency of infections where surgical incisions are performed. In the prevention of healing disorders, the medical staff intervention is important, as is the patient. The management of wound infection after sternotomy requires a holistic approach. It requires the implementation of adequate antibiotic therapy, surgical treatment of the wound, and, if necessary, reconstruction of tissue defects using skin, muscle, and skin-muscle grafts or greater omentum. The prevention of surgical site infection should be based on asepsis and antisepsis at every stage of surgical treatment; the elimination of modifiable risk factors; and an appropriate, staged, and tension-free technique of chest closure. The described actions are aimed at avoiding the most serious complication associated with a high mortality rate in the form of mediastinitis. The therapeutic procedures are strictly dependent on the degree of tissue involvement and the presented clinical manifestation. During the preparation of this manuscript, scientific publications available on the Pubmed platform were analyzed. The scope of the search was limited to the years 2014-2024. The key words were "sternotomy wound infection". A total of 114 publications were analyzed, and 56 of them were included. A total of 23 papers were used to discuss the topic.

ECM Microenvironment in Vascular Homeostasis: New Targets for Atherosclerosis

Alterations in vascular extracellular matrix (ECM) components, interactions, and mechanical properties influence both the formation and stability of atherosclerotic plaques. This review discusses the contribution of the ECM microenvironment in vascular homeostasis and remodeling in atherosclerosis, highlighting Cartilage oligomeric matrix protein (COMP) and its degrading enzyme ADAMTS7 as examples, and proposes potential avenues for future research aimed at identifying novel therapeutic targets for atherosclerosis based on the ECM microenvironment.

Periadventitial biomaterials to improve arteriovenous fistula and graft outcomes

Periadventitial biomaterials have been employed for nearly three decades to promote adaptive venous remodeling following hemodialysis vascular access creation in preclinical models and clinical trials. These systems are predicated on the combination of scaffolds, hydrogels, and/or particles with therapeutics (small molecules, proteins, genes, and cells) to prevent venous stenosis and subsequent maturation failure. Periadventitial biomaterial therapies have evolved from simple drug delivery vehicles for traditional drugs to more thoughtful designs tailored to the pathophysiology of access failure. The emergence of tissue engineering strategies and gene therapies are another exciting new direction. Despite favorable results in experimental and preclinical studies, no periadventitial therapy has been clinically approved to improve vascular access outcomes. After conducting an exhaustive review of the literature, we identify the seminal studies and clinical trials that utilize periadventitial biomaterials and discuss the key features of each biomaterial format and their respective shortcomings as they pertain to access maturation. This review provides a foundation from which clinicians, surgeons, biologists, and engineers can refer to and will hopefully inspire thoughtful, translatable treatments to finally address access failure.

Matrix stiffness, endothelial dysfunction and atherosclerosis

Atherosclerosis (AS) is the leading cause of the human cardiovascular diseases (CVDs). Endothelial dysfunction promotes the monocytes infiltration and inflammation that participate fundamentally in atherogenesis. Endothelial cells (EC) have been recognized as mechanosensitive cells and have different responses to distinct mechanical stimuli. Emerging evidence shows matrix stiffness-mediated EC dysfunction plays a vital role in vascular disease, but the underlying mechanisms are not yet completely understood. This article aims to summarize the effect of matrix stiffness on the pro-atherosclerotic characteristics of EC including morphology, rigidity, biological behavior and function as well as the related mechanical signal. The review also discusses and compares the contribution of matrix stiffness-mediated phagocytosis of macrophages and EC to AS progression. These advances in our understanding of the relationship between matrix stiffness and EC dysfunction open the avenues to improve the prevention and treatment of now-ubiquitous atherosclerotic diseases.

Experimental Liver Cirrhosis Inhibits Restenosis after Balloon Angioplasty

The effect of liver cirrhosis on vascular remodeling in vivo remains unknown. Therefore, this study investigates the influence of cholestatic liver cirrhosis on carotid arterial remodeling. A total of 79 male Sprague Dawley rats underwent bile duct ligation (cirrhotic group) or sham surgery (control group) and 28 days later left carotid artery balloon dilatation; 3, 7, 14 and 28 days after balloon dilatation, the rats were euthanized and carotid arteries were harvested. Histological sections were planimetrized, cell counts determined, and systemic inflammatory parameters measured. Up to day 14 after balloon dilatation, both groups showed a comparable increase in neointima area and degree of stenosis. By day 28, however, both values were significantly lower in the cirrhotic group (% stenosis: 20 ± 8 vs. 42 ± 10, p = 0.010; neointimal area [mm²]: 0.064 ± 0.025 vs. 0.138 ± 0.025, p = 0.024). Simultaneously, cell density in the neointima (p = 0.034) and inflammatory parameters were significantly higher in cirrhotic rats. This study demonstrates that cholestatic liver cirrhosis in rats substantially increases neointimal cell consolidation between days 14 and 28. Thereby, consolidation proved important for the degree of stenosis. This may suggest that patients with cholestatic cirrhosis are at lower risk for restenosis after coronary intervention.

ROLE OF HYALURONAN IN PATHOPHYSIOLOGY OF VASCULAR1 ENDOTHELIAL AND SMOOTH MUSCLE CELLS

One of the main components of the extracellular matrix (ECM) of the blood vessel is hyaluronic acid or hyaluronan (HA). It is a ubiquitous polysaccharide belonging to the family of glycosaminoglycans, but, differently from other proteoglycan-associated glycosaminoglycans, it is synthesized on the plasma membrane by a family of three HA synthases (HAS). HA can be released as a free polymer in the extracellular space or remain associated with the membrane in the pericellular space via HAS or via binding proteins. In fact, several cell surface proteins can interact with HA working as HA receptors like CD44, RHAMM, and LYVE-1. In physiological conditions, HA is localized in the glycocalyx and in the adventitia and is responsible for the loose and hydrated vascular structure favoring flexibility and allowing the stretching of vessels in response to mechanical forces. During atherogenesis, ECM undergoes dramatic alterations which have a crucial role in lipoprotein retention and in triggering multiple signaling cascades that wake up cells from their quiescent status. HA becomes highly present in the media and neointima favoring smooth muscle cells dedifferentiation, migration, and proliferation that strongly contribute to vessel wall thickening. Further, HA is able to modulate immune cell recruitment both within the vessel wall and on the endothelial cell layer. This review is focused on the effects of HA on vascular cell behavior.

Densification: Hyaluronan Aggregation in Different Human Organs

Hyaluronan (HA) has complex biological roles that have catalyzed clinical interest in several fields of medicine. In this narrative review, we provide an overview of HA aggregation, also called densification, in human organs. The literature suggests that HA aggregation can occur in the liver, eye, lung, kidney, blood vessel, muscle, fascia, skin, pancreatic cancer and malignant melanoma. In all these organs, aggregation of HA leads to an increase in extracellular matrix viscosity, causing stiffness and organ dysfunction. Fibrosis, in some of these organs, may also occur as a direct consequence of densification in the long term. Specific imaging evaluation, such dynamic ultrasonography, elasto-sonography, elasto-MRI and T1ρ MRI can permit early diagnosis to enable the clinician to organize the treatment plan and avoid further progression of the pathology and dysfunction.

Reduction of Stabilin-2 Contributes to a Protection Against Atherosclerosis

We have previously identified a novel atherosclerosis quantitative trait locus (QTL), Arch atherosclerosis 5 (Aath5), on mouse chromosome 10 by three-way QTL analyses between Apoe−/− mice on a DBA/2J, 129S6 and C57BL/6J background. The DBA/2J haplotype at the Aath5 locus was associated with smaller plaque size. One of the candidate genes underlying Aath5 was Stabilin-2 (Stab2), which encodes a clearance receptor for hyaluronan (HA) predominantly expressed in liver sinusoidal endothelial cells (LSECs). However, the role of Stab2 in atherosclerosis is unknown. A congenic line of Apoe−/− mice carrying Aath5 covering the Stab2DBA allele on a background of 129S6 confirmed the small reductions of atherosclerotic plaque development. To further determine whether Stab2 is an underlying gene for Aath5, we generated Stab2−/−Apoe−/− mice on a C57BL/6J background. When fed with a Western diet for 8 weeks, Stab2−/−Apoe−/− males developed approximately 30% smaller plaques than Stab2+/+Apoe−/− mice. HA was accumulated in circulation but not in major organs in the Stab2 deficient mice. STAB2-binding molecules that are involved in atherosclerosis, including acLDL, apoptotic cells, heparin and vWF were not likely the direct cause of the protection in the Stab2−/−Apoe−/− males. These data indicate that reduction of Stab2 is protective against atherosclerotic plaque development, and that Stab2 is a contributing gene underlying Aath5, although its effect is small. To test whether non-synonymous amino acid changes unique to DBA/2J affect the function of STAB2 protein, we made HEK293 cell lines expressing STAB2129 or STAB2DBA proteins, as well as STAB2129 proteins carrying each of five DBA-unique replacements that have been predicted to be deleterious. These mutant cells were capable of internalizing 125I -HA and DiI-acLDL similarly to the control cells. These results indicate that the amino acid changes unique to DBA/2J are not affecting the function of STAB2 protein, and support our previous observation that the reduced transcription of Stab2 in the liver sinusoid as a consequence of the insertion of a viral-derived sequence, intracisternal A particle, is the primary contributor to the athero-protection conferred by the DBA/2J allele.

Enhanced Liver Fibrosis Score as a Biomarker for Vascular Damage Assessment in Patients with Takayasu Arteritis-A Pilot Study

Takayasu Arteritis (TA) is characterized by granulomatous panarteritis, vessel wall fibrosis, and irreversible vascular impairment. The aim of this study is to explore the usefulness of the Enhanced Liver Fibrosis score (ELF), procollagen-III aminoterminal propeptide (PIIINP), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), and hyaluronic acid (HA) in assessing vascular damage in TA patients. ELF, PIIINP, TIMP-1, and HA were measured in 24 TA patients, and the results were correlated with the clinical damage indexes (VDI and TADS), an imaging damage score (CARDS), and disease activity scores (NIH and ITAS2010). A mean ELF score 8.42 (±1.12) and values higher than 7.7 (cut-off for liver fibrosis) in 21/24 (87.5%) of patients were detected. The VDI and TADS correlated significantly to ELF (p < 0.01). Additionally, a strong association across ELF and CARDS (p < 0.0001), PIIINP and CARDS (p < 0.001), and HA and CARDS (p < 0.001) was observed. No correlations of the tested biomarkers with inflammatory parameters, NIH, and ITAS2010 scores were found. To our knowledge, this is the first study that suggests the association of the serum biomarkers PIIINP, HA, and ELF score with damage but not with disease activity in TA patients. The ELF score and PIIINP may be useful biomarkers reflecting an ongoing fibrotic process and quantifying vascular damage.

SMC-Derived Hyaluronan Modulates Vascular SMC Phenotype in Murine Atherosclerosis

[Figure: see text].

Balloon Angioplasty of Infrapopliteal Arteries: A Systematic Review and Proposed Algorithm for Optimal Endovascular Therapy

Endovascular revascularization has been increasingly utilized to treat patients with chronic limb-threatening ischemia (CLTI), particularly atherosclerotic disease in the infrapopliteal arteries. Lesions of the infrapopliteal arteries are the result of 2 different etiologies: medial calcification and intimal atheromatous plaque. Although several devices are available for endovascular treatment of infrapopliteal lesions, balloon angioplasty still comprises the mainstay of therapy due to a lack of purpose-built devices. The mechanism of balloon angioplasty consists of adventitial stretching, medial necrosis, and dissection or plaque fracture. In many cases, the diffuse nature of infrapopliteal disease and plaque complexity may lead to dissection, recoil, and early restenosis. Optimal balloon angioplasty requires careful attention to assessment of vessel calcification, appropriate vessel sizing, and the use of long balloons with prolonged inflation times, as outlined in a treatment algorithm based on this systematic review. Further development of specific devices for this arterial segment are warranted, including devices for preventing recoil (eg, dedicated atherectomy devices), treating dissections (eg, tacks, stents), and preventing neointimal hyperplasia (eg, novel drug delivery techniques and drug-eluting stents). Further understanding of infrapopliteal disease, along with the development of new technologies, will help optimize the durability of endovascular interventions and ultimately improve the limb-related outcomes of patients with CLTI.

Fibulin-1 Integrates Subendothelial Extracellular Matrices and Contributes to Anatomical Closure of the Ductus Arteriosus

OBJECTIVE

The ductus arteriosus (DA) is a fetal artery connecting the aorta and pulmonary arteries. Progressive matrix remodeling, that is, intimal thickening (IT), occurs in the subendothelial region of DA to bring anatomic DA closure. IT is comprised of multiple ECMs (extracellular matrices) and migrated smooth muscle cells (SMCs). Because glycoprotein fibulin-1 binds to multiple ECMs and regulates morphogenesis during development, we investigated the role of fibulin-1 in DA closure. Approach and Results: Fibulin-1-deficient (Fbln1^-/-) mice exhibited patent DA with hypoplastic IT. An unbiased transcriptome analysis revealed that EP4 (prostaglandin E receptor 4) stimulation markedly increased fibulin-1 in DA-SMCs via phospholipase C-NFκB (nuclear factor κB) signaling pathways. Fluorescence-activated cell sorting (FACS) analysis demonstrated that fibulin-1 binding protein versican was derived from DA-endothelial cells (ECs). We examined the effect of fibulin-1 on directional migration toward ECs in association with versican by using cocultured DA-SMCs and ECs. EP4 stimulation promoted directional DA-SMC migration toward ECs, which was attenuated by either silencing fibulin-1 or versican. Immunofluorescence demonstrated that fibulin-1 and versican V0/V1 were coexpressed at the IT of wild-type DA, whereas 30% of versican-deleted mice lacking a hyaluronan binding site displayed patent DA. Fibulin-1 expression was attenuated in the EP4-deficient mouse (Ptger4^-/-) DA, which exhibits patent DA with hypoplastic IT, and fibulin-1 protein administration restored IT formation. In human DA, fibulin-1 and versican were abundantly expressed in SMCs and ECs, respectively.

CONCLUSIONS

Fibulin-1 contributes to DA closure by forming an environment favoring directional SMC migration toward the subendothelial region, at least, in part, in combination with EC-derived versican and its binding partner hyaluronan.

Effects of a Matrix Metalloproteinase Inhibitor-Eluting Stent on In-Stent Restenosis

Background

The aim of this study was to compare changes in the extracellular matrix after implantation of a stent that elutes a matrix metalloproteinase (MMP) inhibitor (GM6001); and to determine the effects of the GM6001-eluting stent upon prevention of in-stent restenosis (ISR).

Material/Methods

We included 48 Guangxi Bama mini-pigs in this study. A GM6001-eluting stent was placed in one iliac artery and a stent that did not elute GM6001 was placed in the contralateral iliac artery. The iliac arteries were removed at 6 hours as well as 1, 7, 14, 56, 84, and 336 days after stent placement. Arteries were analyzed for morphometry, gelatinase content, different phenotypes of vascular smooth muscle cells (VSMCs), collagen content, apoptotic rate, and cell density.

Results

The vascular lumen areas of the GM6001 group were significantly increased and the neointimal areas were significantly reduced compared with the control group from the 7 days to the 336 days. In the 2 groups, expression of MMP-2 and MMP-9 peaked simultaneously, but GM6001-eluting stents inhibited expression of MMP-2 and MMP-9 in the vascular media and neointima (especially around the struts) significantly. In the GM6001 group, expression of tissue inhibitor of matrix metalloproteinase (TIMP)-1, TIMP-2, myosin heavy chain 10 (MYH-10, marker of the proliferative phenotype of VSMCs), collagen content, percentage of apoptotic cells, and cell density were also decreased significantly compared with those in the control group.

Conclusion

Use of GM6001-eluting stents resulted in persistent and potent inhibition of intimal hyperplasia, an increase in luminal area, and no obvious thrombosis in the arteries of the mini-pigs.

Aortic Valve Regurgitation: Pathophysiology and Implications for Surgical Intervention in the Era of TAVR

Aortic insufficiency (AI) or regurgitation is caused by the malcoaptation of the aortic valve (AV) cusps due to intrinsic abnormalities of the valve itself, a dilatation or geometric distortion of the aortic root, or by some combination thereof. In recent years, there has been an increase in the number of studies suggesting that AI is an active disease process caused by a combination of factors including but not limited to alteration of specific molecular pathways, genetic predisposition, and changes in the mechanotransductive properties of the AV apparatus. As the surgical management of AV disease continues to evolve, increasingly sophisticated surgical and percutaneous techniques for AV repair and replacement, including transcatheter aortic valve replacement (TAVR), have become more commonplace and will likely continue to expand as new devices are introduced. However, these techniques necessitate frequent reappraisal of the biological and mechanobiological mechanisms underlying AV regurgitation to better understand the risk factors for AI development and recurrence following surgical intervention as well as expand our limited knowledge on patient selection for such procedures. The aim of this review is to describe some of the putative mechanisms implicated in the development of AI, dissect some of the cross-talk among known and possible signaling pathways leading to valve remodeling, identify association between these pathways and pharmacological approaches, and discuss the implications for surgical and percutaneous approaches to AV repair in replacement in the TAVR era.

Homozygous receptors for insulin and not IGF-1 accelerate intimal hyperplasia in insulin resistance and diabetes

Insulin and IGF-1 actions in vascular smooth muscle cells (VSMC) are associated with accelerated arterial intima hyperplasia and restenosis after angioplasty, especially in diabetes. To distinguish their relative roles, we delete insulin receptor (SMIRKO) or IGF-1 receptor (SMIGF1RKO) in VSMC and in mice. Here we report that intima hyperplasia is attenuated in SMIRKO mice, but not in SMIGF1RKO mice. In VSMC, deleting IGF1R increases homodimers of IR, enhances insulin binding, stimulates p-Akt and proliferation, but deleting IR decreases responses to insulin and IGF-1. Studies using chimeras of IR(extracellular domain)/IGF1R(intracellular-domain) or IGF1R(extracellular domain)/IR(intracellular-domain) demonstrate homodimer IRα enhances insulin binding and signaling which is inhibited by IGF1Rα. RNA-seq identifies hyaluronan synthase2 as a target of homo-IR, with its expression increases by IR activation in SMIGF1RKO mice and decreases in SMIRKO mice. Enhanced intima hyperplasia in diabetes is mainly due to insulin signaling via homo-IR, associated with increased Has2 expression.

Non-coding RNAs in vascular remodeling and restenosis

Vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) are crucial in vascular remodeling. They exert pivotal roles in the development and progression of atherosclerosis, vascular response to injury, and restenosis after transcatheter angioplasty. As a witness of their importance in the cardiovascular system, a large body of evidence has accumulated about the role played by micro RNAs (miRNA) in modulating both VSMCs and ECs. More recently, a growing number of long noncoding RNA (lncRNAs) came beneath the spotlights in this research field. Several mechanisms have been revealed by which lncRNAs are able to exert a relevant biological impact on vascular remodeling. The aim of this review is to provide an integrated summary of ncRNAs that exert a relevant biological function in VSMCs and ECs of the vascular wall, with emphasis on the available clinical evidence of the potential usefulness of these molecules as circulating biomarkers of in-stent restenosis.

The CD44-HA axis and inflammation in atherosclerosis: A temporal perspective

Cardiovascular disease (CVD) due to atherosclerosis is a disease of chronic inflammation at both the systemic and the tissue level. CD44 has previously been implicated in atherosclerosis in both humans and mice. This multi-faceted receptor plays a critical part in the inflammatory response during the onset of CVD, though little is known of CD44's role during the latter stages of the disease. This review focuses on the role of CD44-dependent HA-dependent effects on inflammatory cells in several key processes, from disease initiation throughout the progression of atherosclerosis. Understanding how CD44 and HA regulate inflammation in atherogenesis is key in determining the utility of the CD44-HA axis as a therapeutic target to halt disease and potentially promote disease regression.

Intracellular cAMP Sensor EPAC: Physiology, Pathophysiology, and Therapeutics Development

This review focuses on one family of the known cAMP receptors, the exchange proteins directly activated by cAMP (EPACs), also known as the cAMP-regulated guanine nucleotide exchange factors (cAMP-GEFs). Although EPAC proteins are fairly new additions to the growing list of cAMP effectors, and relatively "young" in the cAMP discovery timeline, the significance of an EPAC presence in different cell systems is extraordinary. The study of EPACs has considerably expanded the diversity and adaptive nature of cAMP signaling associated with numerous physiological and pathophysiological responses. This review comprehensively covers EPAC protein functions at the molecular, cellular, physiological, and pathophysiological levels; and in turn, the applications of employing EPAC-based biosensors as detection tools for dissecting cAMP signaling and the implications for targeting EPAC proteins for therapeutic development are also discussed.

Understanding the role of non-coding RNA (ncRNA) in stent restenosis

Coronary heart disease (CHD) is one of the leading disorders with the highest mortality rate. Percutaneous angioplasty and stent implantation are the currently available standard methods for the treatment of obstructive coronary artery disease. However, the stent being an exogenous substance causes several complications by promoting the proliferation of vascular smooth muscle cells, immune responses and neointima formation after implantation, leading to post-stent restenosis (ISR) and late thrombosis. The prevention of these adverse vascular events is important to achieve long-term proper functioning of the heart after stent implantation. Non-coding ribonucleic acids (ncRNAs) are RNA molecules not translated into proteins, theyhave a great potential in regulating endothelial cell and vascular smooth muscle function as well as inflammatory reactions. In this review, we outline the regulatory functions of different classes of ncRNA in cardiovascular disease and propose ncRNAs as new targets for stent restonosis treatment.

Role of hyaluronan in atherosclerosis: Current knowledge and open questions

Hyaluronan (HA), HA synthases (HAS) and HA receptors are expressed during the progression of atherosclerotic plaques. HA is thought to promote the activated phenotype of local vascular smooth muscle cells characterized by increased migration, proliferation and matrix synthesis. Furthermore, HA may modulate the immune response by increasing macrophage retention and by promoting the polarization of Th1 cells that enhance macrophage driven inflammation as well. The pro-atherosclerotic functions of HA are opposed by the presence of HA in the glycocalyx where it critically contributes to anti-thrombotic and anti-inflammatory function of the glycocalyx. Patients with atherosclerosis often are affected by comorbidities among them diabetes mellitus type 2 and inflammatory comorbidities. Diabetes mellitus type 2 likely has close interrelations to HA synthesis in atherosclerosis because the activity and transcription of HA synthases are sensitive to the intracellular glucose metabolism, which determines the substrate availability and the posttranslational modifications of HA synthases. The pro-inflammatory comorbidities aggravate the course of atherosclerosis and will affect the expression of the genes related to HA biosynthesis, -degradation, HA-matrix assembly or signaling. One example being the induction of HAS3 by interleukin-1β and other cytokines. Furthermore complications of atherosclerosis such as the healing after myocardial infarction also involve HA responses.

Microsomal Prostaglandin E Synthase-1 Expression by Aortic Smooth Muscle Cells Attenuates the Differentiated Phenotype

The development of numerous types of cardiovascular disease is associated with alteration of the vascular smooth muscle cell (SMC) phenotype. We have previously shown that abdominal aortic aneurysm progression in a mouse model of the disease is associated with reduced differentiation of SMCs within the lesion and that cyclooxygenase-2 (COX-2) is critical to initiation and progression of the aneurysms. The current studies used human aortic SMC (hASMC) cultures to better characterize mechanisms responsible for COX-2-dependent modulation of the SMC phenotype. Depending on the culture conditions, hASMCs expressed multiple characteristics of a differentiated and contractile phenotype, or a dedifferentiated and secretory phenotype. The pharmacological inhibition of COX-2 promoted the differentiated phenotype, whereas treatment with the COX-2-derived metabolite prostaglandin E2 (PGE2) increased characteristics of the dedifferentiated phenotype. Furthermore, pharmacological inhibition or siRNA-mediated knockdown of microsomal prostaglandin E synthase-1 (mPGES-1), the enzyme that functions downstream of COX-2 during the synthesis of PGE2, significantly increased expression of characteristics of the differentiated SMC phenotype. Therefore, our findings suggest that COX-2 and mPGES-1-dependent synthesis of PGE2 contributes to a dedifferentiated hASMC phenotype and that mPGES-1 may provide a novel pharmacological target for treatment of cardiovascular diseases where altered SMC differentiation has a causative role.

Hyaluronan synthase 3 promotes plaque inflammation and atheroprogression

OBJECTIVE

Hyaluronan (HA) is a prominent component of the provisional extracellular matrix (ECM) present in the neointima of atherosclerotic plaques. Here the role of HA synthase 3 (HAS3) in atheroprogression was studied.

APPROACH AND RESULTS

It is demonstrated here that HAS isoenzymes 1, -2 and -3 are expressed in human atherosclerotic plaques of the carotid artery. In Apolipoprotein E (Apoe)-deficient mice Has3 expression is increased early during lesion formation when macrophages enter atherosclerotic plaques. Importantly, HAS3 expression in vascular smooth muscle cells (VSMC) was found to be regulated by interleukin 1 β (IL-1β) in an NFkB dependent manner and blocking antibodies to IL-1β abrogate Has3 expression in VSMC by activated macrophages. Has3/Apoe double deficient mice developed less atherosclerosis characterized by decreased Th1-cell responses, decreased IL-12 release, and decreased macrophage-driven inflammation.

CONCLUSIONS

Inhibition of HAS3-dependent synthesis of HA dampens systemic Th1 cell polarization and reduces plaque inflammation. These data suggest that HAS3 might be a promising therapeutic target in atherosclerosis. Moreover, because HAS3 is regulated by IL-1β, our results suggest that therapeutic anti-IL-1β antibodies, recently tested in human clinical trials (CANTOS), may exert their beneficial effects on inflammation in post-myocardial infarction patients in part via effects on HAS3. TOC categorybasic study TOC subcategoryarteriosclerosis.

CD44 Promotes Inflammation and Extracellular Matrix Production During Arteriovenous Fistula Maturation

OBJECTIVE

Arteriovenous fistulae (AVF) remain the optimal conduit for hemodialysis access but continue to demonstrate poor patency and poor rates of maturation. We hypothesized that CD44, a widely expressed cellular adhesion molecule that serves as a major receptor for extracellular matrix components, promotes wall thickening and extracellular matrix deposition during AVF maturation.

APPROACH AND RESULTS

AVF were created via needle puncture in wild-type C57BL/6J and CD44 knockout mice. CD44 mRNA and protein expression was increased in wild-type AVF. CD44 knockout mice showed no increase in AVF wall thickness (8.9 versus 26.8 μm; P=0.0114), collagen density, and hyaluronic acid density, but similar elastin density when compared with control AVF. CD44 knockout mice also showed no increase in vascular cell adhesion molecule-1 expression, intercellular adhesion molecule-1 expression, and monocyte chemoattractant protein-1 expression in the AVF compared with controls; there were also no increased M2 macrophage markers (transglutaminase-2: 81.5-fold, P=0.0015; interleukin-10: 7.6-fold, P=0.0450) in CD44 knockout mice. Delivery of monocyte chemoattractant protein-1 to CD44 knockout mice rescued the phenotype with thicker AVF walls (27.2 versus 14.7 μm; P=0.0306), increased collagen density (2.4-fold; P=0.0432), and increased number of M2 macrophages (2.1-fold; P=0.0335).

CONCLUSIONS

CD44 promotes accumulation of M2 macrophages, extracellular matrix deposition, and wall thickening during AVF maturation. These data show the association of M2 macrophages with wall thickening during AVF maturation and suggest that enhancing CD44 activity may be a strategy to increase AVF maturation.

Flow Perturbation Mediates Neutrophil Recruitment and Potentiates Endothelial Injury via TLR2 in Mice: Implications for Superficial Erosion

RATIONALE

Superficial erosion currently causes up to a third of acute coronary syndromes; yet, we lack understanding of its mechanisms. Thrombi because of superficial intimal erosion characteristically complicate matrix-rich atheromata in regions of flow perturbation.

OBJECTIVE

This study tested in vivo the involvement of disturbed flow and of neutrophils, hyaluronan, and Toll-like receptor 2 ligation in superficial intimal injury, a process implicated in superficial erosion.

METHODS AND RESULTS

In mouse carotid arteries with established intimal lesions tailored to resemble the substrate of human eroded plaques, acute flow perturbation promoted downstream endothelial cell activation, neutrophil accumulation, endothelial cell death and desquamation, and mural thrombosis. Neutrophil loss-of-function limited these findings. Toll-like receptor 2 agonism activated luminal endothelial cells, and deficiency of this innate immune receptor decreased intimal neutrophil adherence in regions of local flow disturbance, reducing endothelial cell injury and local thrombosis (P<0.05).

CONCLUSIONS

These results implicate flow disturbance, neutrophils, and Toll-like receptor 2 signaling as mechanisms that contribute to superficial erosion, a cause of acute coronary syndrome of likely growing importance in the statin era.

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.

Smooth Muscle Enriched Long Noncoding RNA (SMILR) Regulates Cell Proliferation

BACKGROUND

Phenotypic switching of vascular smooth muscle cells from a contractile to a synthetic state is implicated in diverse vascular pathologies, including atherogenesis, plaque stabilization, and neointimal hyperplasia. However, very little is known about the role of long noncoding RNA (lncRNA) during this process. Here, we investigated a role for lncRNAs in vascular smooth muscle cell biology and pathology.

METHODS AND RESULTS

Using RNA sequencing, we identified >300 lncRNAs whose expression was altered in human saphenous vein vascular smooth muscle cells following stimulation with interleukin-1α and platelet-derived growth factor. We focused on a novel lncRNA (Ensembl: RP11-94A24.1), which we termed smooth muscle-induced lncRNA enhances replication (SMILR). Following stimulation, SMILR expression was increased in both the nucleus and cytoplasm, and was detected in conditioned media. Furthermore, knockdown of SMILR markedly reduced cell proliferation. Mechanistically, we noted that expression of genes proximal to SMILR was also altered by interleukin-1α/platelet-derived growth factor treatment, and HAS2 expression was reduced by SMILR knockdown. In human samples, we observed increased expression of SMILR in unstable atherosclerotic plaques and detected increased levels in plasma from patients with high plasma C-reactive protein.

CONCLUSIONS

These results identify SMILR as a driver of vascular smooth muscle cell proliferation and suggest that modulation of SMILR may be a novel therapeutic strategy to reduce vascular pathologies.

Long-term effect of PROLI/NO on cellular proliferation and phenotype after arterial injury

Vascular interventions are associated with high failure rates from restenosis secondary to negative remodeling and neointimal hyperplasia. Periadventitial delivery of nitric oxide (NO) inhibits neointimal hyperplasia, preserving lumen patency. With the development of new localized delivery vehicles, NO-based therapies remain a promising therapeutic avenue for the prevention of restenosis. While the time course of events during neointimal development has been well established, a full characterization of the impact of NO donors on the cells that comprise the arterial wall has not been performed. Thus, the aim of our study was to perform a detailed assessment of proliferation, cellularity, inflammation, and phenotypic cellular modulation in injured arteries treated with the short-lived NO donor, PROLI/NO. PROLI/NO provided durable inhibition of neointimal hyperplasia for 6 months after arterial injury. PROLI/NO inhibited proliferation and cellularity in the media and intima at all of the time points studied. However, PROLI/NO caused an increase in adventitial proliferation at 2 weeks, resulting in increased cellularity at 2 and 8 weeks compared to injury alone. PROLI/NO promoted local protein S-nitrosation and increased local tyrosine nitration, without measurable systemic effects. PROLI/NO predominantly inhibited contractile smooth muscle cells in the intima and media, and had little to no effect on vascular smooth muscle cells or myofibroblasts in the adventitia. Finally, PROLI/NO caused a delayed and decreased leukocyte infiltration response after injury. Our results show that a short-lived NO donor exerts durable effects on proliferation, phenotype modulation, and inflammation that result in long-term inhibition of neointimal hyperplasia.

Deletion of Hyaluronan Synthase 3 Inhibits Neointimal Hyperplasia in Mice

OBJECTIVE

Hyaluronan (HA) is a polymeric glucosaminoglycan that forms a provisional extracellular matrix in diseased vessels. HA is synthesized by 3 different HA synthases (HAS1, HAS2, and HAS3). Aim of this study was to unravel the role of the HAS3 isoenzyme during experimental neointimal hyperplasia.

APPROACH AND RESULTS

Neointimal hyperplasia was induced in Has3-deficient mice by ligation of the carotid artery. HA in the media of Has3-deficient mice was decreased 28 days after ligation, and neointimal hyperplasia was strongly inhibited. However, medial and luminal areas were unaffected. Cell density, proliferation, and apoptosis were not altered, suggesting a proportional decrease of both, the number of cells and extracellular matrix. In addition, endothelial function as determined by acetylcholine-induced relaxation of aortic rings, immunoblotting of endothelial nitric oxide synthase, and arterial blood pressure were not affected. Furthermore, the oxidative stress response was not affected as determined in total protein extracts from aortae. Transcriptome analysis comparing control versus ligated carotid arteries hinted toward a mitigated differential regulation of various signaling pathways in Has3-deficient mice in response to ligation that were related to vascular smooth muscle cell (VSMC) migration, including focal adhesions, integrins, mitogen-activated protein kinase, and phosphatidylinositol signaling system. Lentiviral overexpression of HAS3 in VSMC supported the migratory phenotype of VSMC in response to platelet-derived growth factor BB in vitro. Accordingly, knockdown of HAS3 reduced the migratory response to platelet-derived growth factor BB and in addition decreased the expression of PDGF-B mRNA.

CONCLUSIONS

HAS3-mediated HA synthesis after vessel injury supports seminal signaling pathways in activation of VSMC, increases platelet-derived growth factor BB-mediated migration, and in turn enhances neointimal hyperplasia in vivo.

Regulation of hyaluronan synthesis in vascular diseases and diabetes

Cell microenvironment has a critical role determining cell fate and modulating cell responses to injuries. Hyaluronan (HA) is a ubiquitous extracellular matrix glycosaminoglycan that can be considered a signaling molecule. In fact, interacting with several cell surface receptors can deeply shape cell behavior. In vascular biology, HA triggers smooth muscle cells (SMCs) dedifferentiation which contributes to vessel wall thickening. Furthermore, HA is able to modulate inflammation by altering the adhesive properties of endothelial cells. In hyperglycemic conditions, HA accumulates in vessels and can contribute to the diabetic complications at micro- and macrovasculature. Due to the pivotal role in favoring atherogenesis and neointima formation after injuries, HA could be a new target for cardiovascular pathologies. This review will focus on the recent findings regarding the regulation of HA synthesis in human vascular SMCs. In particular, the effects of the intracellular HA substrates availability, adenosine monophosphate-activated protein kinase (AMPK), and protein O-GlcNAcylation on the main HA synthetic enzyme (i.e., HAS2) will be discussed.

Functional Long Non-coding RNAs in Vascular Smooth Muscle Cells

Increasing evidence shows that long non-coding RNAs (lncRNAs) are not "transcriptional noise" but function in a myriad of biological processes. As such, this rapidly growing class of RNAs is important in both development and disease. Vascular smooth muscle cells are integral cells of the blood vessel wall. They are responsible for relaxation and contraction of the blood vessel and respond to hemodynamic as well as environmental signals to regulate blood pressure. Pathophysiological changes to these cells such as hyperproliferation, hypertrophy, migration, and inflammation contribute to cardiovascular diseases (CVDs) such as restenosis, hypertension, and atherosclerosis. Understanding the molecular mechanisms involved in these pathophysiological changes to VSMCs is paramount to developing therapeutic treatments for various cardiovascular disorders. Recent studies have shown that lncRNAs are key players in the regulation of VSMC functions and phenotype and, perhaps also, in the development of VSMC-related diseases. This chapter describes our current understanding of the functions of lncRNAs in VSMCs. It highlights the emerging role of lncRNAs in VSMC proliferation and apoptosis, their role in contractile and migratory phenotype of VSMCs, and their potential role in VSMC disease states.

Bacterial cellulose–hyaluronan nanocomposite biomaterials as wound dressings for severe skin injury repair

BC–HA composite dressings have better performance in wound healing.

Natural antisense transcript for hyaluronan synthase 2 (HAS2-AS1) induces transcription of HAS2 via protein O-GlcNAcylation

Changes in the microenvironment organization within vascular walls are critical events in the pathogenesis of vascular pathologies, including atherosclerosis and restenosis. Hyaluronan (HA) accumulation into artery walls supports vessel thickening and is involved in many cardiocirculatory diseases. Excessive cytosolic glucose can enter the hexosamine biosynthetic pathway, increase UDP-N-acetylglucosamine (UDP-GlcNAc) availability, and lead to modification of cytosolic proteins via O-linked attachment of the monosaccharide β-N-GlcNAc (O-GlcNAcylation) from UDP-GlcNAc by the enzyme O-GlcNAc transferase. As many cytoplasmic and nuclear proteins can be glycosylated by O-GlcNAc, we studied whether the expression of the HA synthases that synthesize HA could be controlled by O-GlcNAcylation in human aortic smooth muscle cells. Among the three HAS isoenzymes, only HAS2 mRNA increased after O-GlcNAcylation induced by glucosamine treatments or by inhibiting O-GlcNAc transferase with PUGNAC (O-(2-acetamido-2-deoxy-d-glucopyranosylidene)amino-N-phenylcarbamate). We found that the natural antisense transcript of HAS2 (HAS2-AS1) was absolutely necessary to induce the transcription of the HAS2 gene. Moreover, we found that O-GlcNAcylation modulated HAS2-AS1 promoter activation by recruiting the NF-κB subunit p65, but not the HAS2 promoter, whereas HAS2-AS1 natural antisense transcript, working in cis, regulated HAS2 transcription by altering the chromatin structure around the HAS2 proximal promoter via O-GlcNAcylation and acetylation. These results indicate that HAS2 transcription can be finely regulated not only by recruiting transcription factors to the promoter as previously described but also by modulating chromatin accessibility by epigenetic modifications.

The relationship between aortic stiffness and serum hyaluronidase levels in patients with diabetes mellitus and hypertension

The aim of this study was to investigate the association of serum hyaluronidase and nitric oxide (NO) levels with arterial stiffness in patients with hypertension (HT) and diabetes mellitus (DM). A total of 101 patients with diagnosis of DM and HT were enrolled in this study. The patients were divided into three groups as follows: only hypertensive (I), only diabetic (II) and both diabetic and hypertensive (III). Serum hyaluronidase levels were negatively correlated with aortic strain (AS) and aortic distensibility (AOD) in all groups, whereas a significant positive correlation was noted between serum hyaluronidase levels and aortic strain index (ASI) (all p-values < 0.05). There was a significant negative correlation between serum hyaluronidase and NO levels in all patients (p < 0.001). When the correlation between serum hyaluronidase and serum NO levels was investigated in the individual patient groups, a negative correlation was found in groups I, II and III (p = 0.017, p < 0.001 and p < 0.001, respectively). A significant relationship between plasma hyaluronidase level and parameters of aortic stiffness was found in patients with HT and/or DM. We suggest that the pathophysiological mechanisms responsible for the development of arterial stiffness in subjects with impaired endothelial function may involve pathological changes in the HA metabolism.

Close relationship between serum hyaluronan levels and vascular function in patients with type 2 diabetes

OBJECTIVE

To clarify the relationship between serum hyaluronan levels and vascular function in type 2 diabetic patients.

METHODS

A cross-sectional cohort study.

RESULTS

In multivariate regression analysis, endothelium-dependent flow-mediated dilation was associated with age and duration of diabetes, but not with serum hyaluronan level, while endothelium-independent nitroglycerine-mediated dilation (NMD) was only associated with serum hyaluronan level (standardized estimate = -0.401, p = 0.003). NMD in the lowest tertile of hyaluronan level was significantly higher than the other tertiles (15.9% versus 12.5% and 10.4%, p = 0.047 and p = 0.002, respectively).

CONCLUSIONS

Serum hyaluronan level may be useful as a surrogate marker for early changes in the vascular function, which often occurs in patients with diabetes mellitus.

The role of the extracellular matrix components in cutaneous wound healing

Wound healing is the physiologic response to tissue trauma proceeding as a complex pathway of biochemical reactions and cellular events, secreted growth factors, and cytokines. Extracellular matrix constituents are essential components of the wound repair phenomenon. Firstly, they create a provisional matrix, providing a structural integrity of matrix during each stage of healing process. Secondly, matrix molecules regulate cellular functions, mediate the cell-cell and cell-matrix interactions, and serve as a reservoir and modulator of cytokines and growth factors' action. Currently known mechanisms, by which extracellular matrix components modulate each stage of the process of soft tissue remodeling after injury, have been discussed.

Internal mammary artery atherosclerosis: an ultrastructural study of two cases

Atherosclerosis of the internal mammary artery (IMA) is generally regarded as a rare (but existent) pathological entity with only a few cases reported in the most recent literature. The only study which to our knowledge has investigated the ultrastructural features of IMA atherosclerosis, demonstrate the presence of endothelial cells loss, defects of internal elastic lamina with no evidence of lipid accumulation. In the present study, we describe two cases of IMA atherosclerosis in which ultrastructural analysis revealed the presence of a typical atherosclerotic plaque morphology with infiltration of inflammatory cells, formation of intraplaque lipid pools, and accumulation of lipid-laden foam cells throughout the thickened intima, never described in this rare lesion before. Microscopically, the lesions were also characterized by intimal thickening, invagination of endothelial cells, migration of smooth muscle cells with splitting, fenestration and/or fragmentation of the elastic sheets. Our observations add new data to the scarce and contradictory literature and to this largely understudied vascular disorder.

Nanoparticle drug- and gene-eluting stents for the prevention and treatment of coronary restenosis

Percutaneous coronary intervention (PCI) has become the most common revascularization procedure for coronary artery disease. The use of stents has reduced the rate of restenosis by preventing elastic recoil and negative remodeling. However, in-stent restenosis remains one of the major drawbacks of this procedure. Drug-eluting stents (DESs) have proven to be effective in reducing the risk of late restenosis, but the use of currently marketed DESs presents safety concerns, including the non-specificity of therapeutics, incomplete endothelialization leading to late thrombosis, the need for long-term anti-platelet agents, and local hypersensitivity to polymer delivery matrices. In addition, the current DESs lack the capacity for adjustment of the drug dose and release kinetics appropriate to the disease status of the treated vessel. The development of efficacious therapeutic strategies to prevent and inhibit restenosis after PCI is critical for the treatment of coronary artery disease. The administration of drugs using biodegradable polymer nanoparticles as carriers has generated immense interest due to their excellent biocompatibility and ability to facilitate prolonged drug release. Despite the potential benefits of nanoparticles as smart drug delivery and diagnostic systems, much research is still required to evaluate potential toxicity issues related to the chemical properties of nanoparticle materials, as well as to their size and shape. This review describes the molecular mechanism of coronary restenosis, the use of DESs, and progress in nanoparticle drug- or gene-eluting stents for the prevention and treatment of coronary restenosis.

Oxidized low density lipoprotein (LDL) affects hyaluronan synthesis in human aortic smooth muscle cells

Thickening of the vessel in response to high low density lipoprotein(s) (LDL) levels is a hallmark of atherosclerosis, characterized by increased hyaluronan (HA) deposition in the neointima. Human native LDL trapped within the arterial wall undergoes modifications such as oxidation (oxLDL). The aim of our study is to elucidate the link between internalization of oxLDL and HA production in vitro, using human aortic smooth muscle cells. LDL were used at an effective protein concentration of 20-50 μg/ml, which allowed 80% cell viability. HA content in the medium of untreated cells was 28.9 ± 3.7 nmol HA-disaccharide/cell and increased after oxLDL treatment to 53.9 ± 5.6. OxLDL treatments doubled the transcripts of HA synthase HAS2 and HAS3. Accumulated HA stimulated migration of aortic smooth muscle cells and monocyte adhesiveness to extracellular matrix. The effects induced by oxLDL were inhibited by blocking LOX-1 scavenger receptor with a specific antibody (10 μg/ml). The cholesterol moiety of LDL has an important role in HA accumulation because cholesterol-free oxLDL failed to induce HA synthesis. Nevertheless, cholesterol-free oxLDL and unmodified cholesterol (20 μg/ml) induce only HAS3 transcription, whereas 22,oxysterol affects both HAS2 and HAS3. Moreover, HA deposition was associated with higher expression of endoplasmic reticulum stress markers (CHOP and GRP78). Our data suggest that HA synthesis can be induced in response to specific oxidized sterol-related species delivered through oxLDL.

Loss of the hyaluronan receptor RHAMM prevents constrictive artery wall remodeling

OBJECTIVE

Constrictive extracellular matrix (ECM) remodeling contributes significantly to restenosis after arterial reconstruction, but its molecular regulation is poorly defined. Hyaluronan (HA) accumulates within ECM at sites of injury where it is thought to facilitate smooth muscle cell (SMC) trafficking and collagen remodeling analogous to its role in cutaneous wound healing. SMC receptors for HA include receptor for hyaluronan-mediated motility (RHAMM), which mediates HA-induced migration. We hypothesized RHAMM would also mediate SMC-matrix interactions to alter the extent of constrictive remodeling.

METHODS

We studied the role of RHAMM in SMC attachment to collagen, migration, and contraction of collagen gels using blocking antibodies and SMC from RHAMM -/- knockout mice. We then determined the role of RHAMM in constrictive artery wall remodeling by comparing changes in wall geometry in RHAMM -/- vs wild-type (WT) RHAMM +/+ controls 1 month after carotid ligation.

RESULTS

HA increased SMC attachment to collagen-coated plates, but blocking RHAMM reduced adhesion (P = .025). RHAMM -/- SMC also demonstrated reduced adhesion (% adherent: 36.1 ± 2.2 vs 76.3 ± 1.9; P < .05). SMC contraction of collagen gels was enhanced by HA and further increased by RHAMM blockade (P < .01) or knockout (gel diameter, mm: RHAMM -/-, 6.7 ± 0.1 vs WT 9.8 ± 0.1; P < .01). RHAMM promoted constrictive remodeling in vivo as carotid artery size was significantly larger in knockout mice 1 month after ligation. Neointimal thickening, however, was not affected in RHAMM -/- (P = NS vs WT), but lumen size was significantly larger (lumen area, μm(2): 52.4 ± 1.4 × 10(3) vs 10.4 ± 1.8 × 10(3); P = .01) because artery size constricted less (external elastic lamina area, μm(2): RHAMM -/-, 92.4 ± 4.7 × 10(3) vs WT, 51.3 ± 5.9 × 10(3); P = .015). Adventitial thickening and collagen deposition were also more extensive in ligated RHAMM -/- carotids (adventitial thickness, μm: 218 ± 12.2 vs 109 ± 7.9; P = .01).

CONCLUSIONS

HA activation of RHAMM significantly impacts SMC-ECM adhesive interactions and contributes to constrictive artery wall remodeling in mice. Strategies to block RHAMM at sites of vessel injury may prove useful in the prevention of clinical restenosis.

Effectiveness of cyclooxygenase-2 inhibition in limiting abdominal aortic aneurysm progression in mice correlates with a differentiated smooth muscle cell phenotype

Abdominal aortic aneurysms (AAAs) are a chronic condition that often progress over years to produce a weakened aorta with increased susceptibility for rupture, and currently, there are no pharmacological treatments available to slow disease progression. AAA development has been characterized by increased expression of cyclooxygenase-2 (COX-2), and inactivation of COX-2 before disease initiation reduces AAA incidence in a mouse model of the disease. The current study determined the effectiveness of COX-2 inhibition on AAA progression when treatment was begun after initiation of the disease. COX-2 inhibitor treatment with celecoxib was initiated after angiotensin II-induced AAA formation in a strain of nonhyperlipidemic mice that we have previously identified as highly susceptible to AAA development. When analyzed at different time points during progression of the disease, celecoxib treatment significantly reduced the incidence and severity of AAAs. The celecoxib treatment also protected the mice from aortic rupture and death. The aneurysmal lesion displayed an altered smooth muscle cell (SMC) phenotype, whereas celecoxib treatment was associated with increased expression of differentiated SMC markers and reduced dedifferentiation marker expression during AAA progression. Maintenance of a differentiated SMC phenotype is associated with the effectiveness of COX-2 inhibition for limiting AAA progression in nonhyperlipidemic mice.

Increased hyaluronan expression at distinct time points in acute lymphedema

Lymphatic dysfunction in lymphedema results in chronic accumulation of interstitial fluid and life-long tissue swelling. In the absence of restored lymphatic drainage via adequate lymphangiogenesis, the interstitial environment can remodel in ways that decrease the elevated interstitial stress. Presently, relatively little is known about the glycosaminoglycans (GAGs) that become upregulated in the interstitium during lymphedema. We employed a mouse tail model of acute lymphedema that reproduces important features of the chronic human condition to establish a relationship between hyaluronan (HA) and sulfated GAG concentration with tissue swelling. We found that HA was upregulated by tissue injury at day 5 and became upregulated again by skin swelling (HA content increasing by 27% relative to controls at days 15 and 20). Surprisingly, the second phase of HA expression was associated with the declining phase of the tail skin swelling (tail diameter significantly decreasing by 17% from day 10 peak to day 20), demonstrating that HA is upregulated by tissue swelling and may help to counteract the edema in the mouse tail. This finding was confirmed by intradermal injection of an HA degrading enzyme (hyaluronidase) to the swollen tail, which was found to worsen the tail swelling. Sulfated GAGs, including chondroitin sulfate (CS), were not regulated by tissue swelling. The results demonstrate that HA, but not sulfated GAGs, is upregulated in the interstitium by acute tissue swelling. We speculate that HA expression during lymphedema may be part of a natural adaptive mechanism of the interstitial environment to reduce capillary filtration and increase interstitial fluid outflow following lymphatic obstruction and fluid accumulation.

Crucial role of hyaluronan in neointimal formation after vascular injury

Background

Hyaluronan (HA) is a primary component of the extracellular matrix of cells, and it is involved in the pathogenesis of atherosclerosis. The purpose of this study was to investigate the role of HA in neointimal formation after vascular injury and determine its tissue-specific role in vascular smooth muscle cells (VSMCs) by using a cre-lox conditional transgenic (cTg) strategy.

Methods and Results

HA was found to be expressed in neointimal lesions in humans with atherosclerosis and after wire-mediated vascular injury in mice. Inhibition of HA synthesis using 4-methylumbelliferone markedly inhibited neointimal formation after injury. In vitro experiments revealed that low-molecular-weight HA (LMW-HA) induced VSMC activation, including migration, proliferation, and production of inflammatory cytokines, and reactive oxygen species (ROS). The migration and proliferation of VSMCs were mediated by the CD44/RhoA and CD44/ERK1/2 pathways, respectively. Because HA synthase 2 (HAS2) is predominantly expressed in injured arteries, we generated cTg mice that overexpress the murine HAS2 gene specifically in VSMCs (cHAS2/CreSM22α mice) and showed that HA overexpression markedly enhanced neointimal formation after cuff-mediated vascular injury. Further, HA-overexpressing VSMCs isolated from cHAS2/CreSM22α mice showed augmented migration, proliferation, and production of inflammatory cytokines and ROS.

Conclusion

VSMC-derived HA promotes neointimal formation after vascular injury, and HA may be a potential therapeutic target for cardiovascular disease.

Novel effects of adenosine receptors on pericellular hyaluronan matrix: implications for human smooth muscle cell phenotype and interactions with monocytes during atherosclerosis

Hyaluronan (HA) is responsive to pro-atherosclerotic growth factors and cytokines and is thought to contribute to neointimal hyperplasia and atherosclerosis. However, the specific function of the pericellular HA matrix is likely depend on the respective stimuli. Adenosine plays an important role in the phenotypic regulation of vascular smooth muscle cells (VSMC) and is thought to inhibit inflammatory responses during atherosclerosis. The aim of this study was to examine the regulation and function of HA matrix in response to adenosine in human coronary artery SMC (HCASMC). The adenosine receptor agonist NECA (10 μM) caused a strong induction of HA synthase (HAS)1 at 6 h and a weaker induction again after 24 h. Use of selective adenosine receptor antagonists revealed that adenosine A2(B) receptors (A2(B)R) mediate the early HAS1 induction, whereas late HAS1 induction was mediated via A2(A)R and A3R. The strong response after 6 h was mediated in part via phosphoinositide-3 kinase- and mitogen-activated protein kinase pathways and was inhibited by Epac. Functionally, NECA increased cell migration, which was abolished by shRNA-mediated knock down of HAS1. In addition to HA secretion, NECA also stimulated the formation of pronounced pericellular HA matrix in HCASMC and increased the adhesion of monocytes. The adenosine-induced monocyte adhesion was sensitive to hyaluronidase. In conclusion, the current data suggest that adenosine via adenosine A2(B)R and A2(A)R/A3R induces HAS1. In turn a HA-rich matrix is formed by HCASMC which likely supports the migratory HCASMC phenotype and traps monocytes/macrophages in the interstitial matrix.

Role of UDP-N-acetylglucosamine (GlcNAc) and O-GlcNAcylation of hyaluronan synthase 2 in the control of chondroitin sulfate and hyaluronan synthesis

Hyaluronan (HA) is a glycosaminoglycan present in most tissue microenvironments that can modulate many cell behaviors, including proliferation, migration, and adhesive proprieties. In contrast with other glycosaminoglycans, which are synthesized in the Golgi, HA is synthesized at the plasma membrane by one or more of the three HA synthases (HAS1-3), which use cytoplasmic UDP-glucuronic acid and UDP-N-acetylglucosamine as substrates. Previous studies revealed the importance of UDP-sugars for regulating HA synthesis. Therefore, we analyzed the effect of UDP-GlcNAc availability and protein glycosylation with O-linked N-acetylglucosamine (O-GlcNAcylation) on HA and chondroitin sulfate synthesis in primary human aortic smooth muscle cells. Glucosamine treatment, which increases UDP-GlcNAc availability and protein O-GlcNAcylation, increased synthesis of both HA and chondroitin sulfate. However, increasing O-GlcNAcylation by stimulation with O-(2-acetamido-2-deoxy-d-glucopyranosylidene)amino-N-phenylcarbamate without a concomitant increase of UDP-GlcNAc increased only HA synthesis. We found that HAS2, the main synthase in aortic smooth muscle cells, can be O-GlcNAcylated on serine 221, which strongly increased its activity and its stability (t(&frac12;) >5 h versus ∼17 min without O-GlcNAcylation). S221A mutation prevented HAS2 O-GlcNAcylation, which maintained the rapid turnover rate even in the presence of GlcN and increased UDP-GlcNAc. These findings could explain the elevated matrix HA observed in diabetic vessels that, in turn, could mediate cell dedifferentiation processes critical in vascular pathologies.

Monocyte-to-macrophage differentiation: synthesis and secretion of a complex extracellular matrix

Although monocyte- and macrophage-derived molecules are known to promote extracellular matrix (ECM) disruption and destabilization, it is less appreciated that they also synthesize molecules contributing to ECM formation, stabilization, and function. We have identified and characterized the synthesis of proteoglycans and related proteins, some not previously known to be associated with macrophages. Proteoglycan extracts of [³⁵S]sulfate- and ³⁵S-trans amino acid-radiolabeled culture media from THP-1 monocytes induced to differentiate by treatment with phorbol myristate acetate revealed three major proteins of ∼25, 90, and 100 kDa following chondroitin ABC lyase digestion. The 25-kDa protein was predominant for monocytes, whereas the 90- and 100-kDa proteins were predominant for macrophages. Tandem mass spectrometry identified (i) the 25-kDa core protein as serglycin, (ii) the 90-kDa core protein as inter-α-inhibitor heavy chain 2 (IαIHC2), and (iii) the 100-kDa core as amyloid precursor-like protein 2 (APLP2). Differentiation was also associated with (i) a >500-fold increase in mRNA for TNF-stimulated gene-6, an essential cofactor for heavy chain-mediated matrix stabilization; (ii) a >800-fold increase in mRNA for HAS2, which is responsible for hyaluronan synthesis; and (iii) a 3-fold increase in mRNA for versican, which interacts with hyaluronan. Biochemical evidence is also presented for an IαIHC2-APLP2 complex, and immunohistochemical staining of human atherosclerotic lesions demonstrates similar staining patterns for APLP2 and IαIHC2 with macrophages, whereas serglycin localizes to the underlying glycosaminoglycan-rich region. These findings indicate that macrophages synthesize many of the molecules participating in ECM formation and function, suggesting a novel role for these molecules in the differentiation of macrophages in the development of atherosclerosis.