Versican degradation and vascular disease

Sesame oil downregulates the expression of ADAMTS-4 in high-fat diet-induced atherosclerosis

Atherosclerosis is a chronic inflammatory disease forming plaques in medium and large-sized arteries. ADAMTS-4 (a disintegrin and metalloproteinase with thrombospondin motifs-4) is an extracellular-matrix remodelling enzyme involved in the degradation of versican in the arterial wall. Recent reports indicated that increased expression of ADAMTS-4 is associated with plaque progression and vulnerability. Bioactive components of dietary oil, like sesame oil, are reported to have anti-inflammatory and antioxidant properties. Here, we studied the effect of sesame oil on regulating ADAMTS-4 in high-fat diet-induced atherosclerosis rat model. Our results indicated that sesame oil supplementation improved the anti-inflammatory and anti-oxidative status of the body. It also reduced atherosclerotic plaque formation in high-fat diet-fed rats. Our results showed that the sesame oil supplementation significantly down-regulated the expression of ADAMTS-4 in serum and aortic samples. The versican, the large proteoglycan substrate of ADAMTS-4 in the aorta, was downregulated to normal control level on sesame oil supplementation. This study, for the first time, reveals that sesame oil could down-regulate the expression of ADAMTS-4 in high-fat diet-induced atherosclerosis, imparting a new therapeutic potential for sesame oil in the management of atherosclerosis.

The Contribution of Vascular Proteoglycans to Atherothrombosis: Clinical Implications

The vascular extracellular matrix (ECM) produced by endothelial and smooth muscle cells is composed of collagens and glycoproteins and plays an integral role in regulating the structure and function of the vascular wall. Alteration in the expression of these proteins is associated with endothelial dysfunction and has been implicated in the development and progression of atherosclerosis. The ECM composition of atherosclerotic plaques varies depending on plaque phenotype and vulnerability, with distinct differences observed between ruptured and erodes plaques. Moreover, the thrombi on the exposed ECM are diverse in structure and composition, suggesting that the best antithrombotic approach may differ depending on plaque phenotype. This review provides a comprehensive overview of the role of proteoglycans in atherogenesis and thrombosis. It discusses the differential expression of the proteoglycans in different plaque phenotypes and the potential impact on platelet function and thrombosis. Finally, the review highlights the importance of this concept in developing a targeted approach to antithrombotic treatments to improve clinical outcomes in cardiovascular disease.

Targeting Chondroitin Sulphate Synthase 1 (Chsy1) Promotes Axon Growth Following Neurorrhaphy by Suppressing Versican Accumulation

Versican is a chondroitin sulfate proteoglycan (CSPG), which deposits in perineurium as a physical barrier and prevents the growth of axons out of the fascial boundary. Several studies have indicated that the chondroitin sulfate (CS) chains on versican have several possible functions beyond the physical barrier, including the ability to stabilize versican core protein in the extracellular matrix. As chondroitin sulfate synthase 1 (Chsy1) is a crucial enzyme for CS elongation, we hypothesized that in vivo knockdown of Chsy1 at peripheral nerve lesion site may decrease CS and versican accumulation, and result in accelerating neurite regeneration. In the present study, end-to-side neurorrhaphy (ESN) in Wistar rats was used as an in vivo model of peripheral nerve injury to evaluate nerve regeneration after surgical intervention. The distribution and expression of versican and Chsy1 in regenerating axons after ESN was studied using confocal microscopy and western blotting. Chsy1 was silenced at the nerve lesion (surgical) site using in vivo siRNA transfection. The results indicated that Chsy1 was successfully silenced in nerve tissue, and its downregulation was associated with functional recovery of compound muscle action potential. Silencing of Chsy1 also decreased the accumulation of versican core protein, suggesting that transient treating of Chsy1-siRNA may be an alternative and an effective strategy to promote injured peripheral nerve regeneration.

Regional and disease specific human lung extracellular matrix composition

Chronic lung diseases, such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF), are characterized by regional extracellular matrix (ECM) remodeling which contributes to disease progression. Previous proteomic studies on whole decellularized lungs have provided detailed characterization on the impact of COPD and IPF on total lung ECM composition. However, such studies are unable to determine the differences in ECM composition between individual anatomical regions of the lung. Here, we employ a post-decellularization dissection method to compare the ECM composition of whole decellularized lungs (wECM) and specific anatomical lung regions, including alveolar-enriched ECM (aECM), airway ECM (airECM), and vasculature ECM (vECM), between non-diseased (ND), COPD, and IPF human lungs. We demonstrate, using mass spectrometry, that individual regions possess a unique ECM signature characterized primarily by differences in collagen composition and basement-membrane associated proteins, including ECM glycoproteins. We further demonstrate that both COPD and IPF lead to alterations in lung ECM composition in a region-specific manner, including enrichment of type-III collagen and fibulin in IPF aECM. Taken together, this study provides methodology for future studies, including isolation of region-specific lung biomaterials, as well as a dataset that may be applied for the identification of novel ECM targets for therapeutics.

Differential Expression and Localization of ADAMTS Proteinases in Proliferative Diabetic Retinopathy

We analyzed the expression of ADAMTS proteinases ADAMTS-1, -2, -4, -5 and -13; their activating enzyme MMP-15; and the degradation products of proteoglycan substrates versican and biglycan in an ocular microenvironment of proliferative diabetic retinopathy (PDR) patients. Vitreous samples from PDR and nondiabetic patients, epiretinal fibrovascular membranes from PDR patients, rat retinas, retinal Müller glial cells and human retinal microvascular endothelial cells (HRMECs) were studied. The levels of ADAMTS proteinases and MMP-15 were increased in the vitreous from PDR patients. Both full-length and cleaved activation/degradation fragments of ADAMTS proteinases were identified. The amounts of versican and biglycan cleavage products were increased in vitreous from PDR patients. ADAMTS proteinases and MMP-15 were localized in endothelial cells, monocytes/macrophages and myofibroblasts in PDR membranes, and ADAMTS-4 was expressed in the highest number of stromal cells. The angiogenic activity of PDR membranes correlated significantly with levels of ADAMTS-1 and -4 cellular expression. ADAMTS proteinases and MMP-15 were expressed in rat retinas. ADAMTS-1 and -5 and MMP-15 levels were increased in diabetic rat retinas. HRMECs and Müller cells constitutively expressed ADAMTS proteinases but not MMP-15. The inhibition of NF-κB significantly attenuated the TNF-α-and-VEGF-induced upregulation of ADAMTS-1 and -4 in a culture medium of HRMECs and Müller cells. In conclusion, ADAMTS proteinases, MMP-15 and versican and biglycan cleavage products were increased in the ocular microenvironment of patients with PDR.

Proteolysis: a key post-translational modification regulating proteoglycans

Proteoglycans are composite molecules comprising a protein backbone, i.e., the core protein, with covalently attached glycosaminoglycan chains of distinct chemical types. Most proteoglycans are secreted or attached to the cell membrane. Their specialized structures, binding properties, and biophysical attributes underlie diverse biological roles, which include modulation of tissue mechanics, cell adhesion, and the sequestration and regulated release of morphogens, growth factors, and cytokines. As an irreversible post-translational modification, proteolysis has a profound impact on proteoglycan function, abundance, and localization. Proteolysis is required for molecular maturation of some proteoglycans, clearance of extracellular matrix proteoglycans during tissue remodeling, generation of bioactive fragments from proteoglycans, and ectodomain shedding of cell-surface proteoglycans. Genetic evidence shows that proteoglycan core protein proteolysis is essential for diverse morphogenetic events during embryonic development. In contrast, dysregulated proteoglycan proteolysis contributes to osteoarthritis, cardiovascular disorders, cancer, and inflammation. Proteolytic fragments of perlecan, versican, aggrecan, brevican, collagen XVIII, and other proteoglycans are associated with independent biological activities as so-called matrikines. Yet, proteoglycan proteolysis has been investigated to only a limited extent to date. Here, we review the actions of proteases on proteoglycans and illustrate their functional impact with several examples. We discuss the applications and limitations of strategies used to define cleavage sites in proteoglycans and explain how proteoglycanome-wide proteolytic mapping, which is desirable to fully understand the impact of proteolysis on proteoglycans, can be facilitated by integrating classical proteoglycan isolation methods with mass spectrometry-based proteomics.

Stem Cell Based Approaches to Modulate the Matrix Milieu in Vascular Disorders

The extracellular matrix (ECM) represents a complex and dynamic framework for cells, characterized by tissue-specific biophysical, mechanical, and biochemical properties. ECM components in vascular tissues provide structural support to vascular cells and modulate their function through interaction with specific cell-surface receptors. ECM–cell interactions, together with neurotransmitters, cytokines, hormones and mechanical forces imposed by blood flow, modulate the structural organization of the vascular wall. Changes in the ECM microenvironment, as in post-injury degradation or remodeling, lead to both altered tissue function and exacerbation of vascular pathologies. Regeneration and repair of the ECM are thus critical toward reinstating vascular homeostasis. The self-renewal and transdifferentiating potential of stem cells (SCs) into other cell lineages represents a potentially useful approach in regenerative medicine, and SC-based approaches hold great promise in the development of novel therapeutics toward ECM repair. Certain adult SCs, including mesenchymal stem cells (MSCs), possess a broader plasticity and differentiation potential, and thus represent a viable option for SC-based therapeutics. However, there are significant challenges to SC therapies including, but not limited to cell processing and scaleup, quality control, phenotypic integrity in a disease milieu in vivo, and inefficient delivery to the site of tissue injury. SC-derived or -inspired strategies as a putative surrogate for conventional cell therapy are thus gaining momentum. In this article, we review current knowledge on the patho-mechanistic roles of ECM components in common vascular disorders and the prospects of developing adult SC based/inspired therapies to modulate the vascular tissue environment and reinstate vessel homeostasis in these disorders.

Defining the Versican Interactome in Lung Health and Disease

The extracellular matrix (ECM) imparts critical mechanical and biochemical information to cells in the lungs. Proteoglycans are essential constituents of the ECM and play a crucial role in controlling numerous biological processes, including regulating cellular phenotype and function. Versican, a chondroitin sulfate proteoglycan required for embryonic development, is almost absent from mature, healthy lungs and is re-expressed and accumulates in acute and chronic lung disease. Studies using genetically engineered mice show that the versican-enriched matrix can be pro- or anti-inflammatory depending on the cellular source or disease process studied. The mechanisms whereby versican develops a contextual ECM remain largely unknown. The primary goal of this review is to provide an overview of the interaction of versican with its many binding partners, the "versican interactome," and how through these interactions, versican is an integrator of complex extracellular information. Hopefully, the information provided in this review will be used to develop future studies to determine how versican and its binding partners can develop contextual ECMs that control select biological processes. While this review focuses on versican and the lungs, what is described can be extended to other proteoglycans, tissues, and organs.

Biomechanical consequences of compromised elastic fiber integrity and matrix cross-linking on abdominal aortic aneurysmal enlargement

Abdominal aortic aneurysms (AAAs) are characterized histopathologically by compromised elastic fiber integrity, lost smooth muscle cells or their function, and remodeled collagen. We used a recently introduced mouse model of AAAs that combines enzymatic degradation of elastic fibers and blocking of lysyl oxidase, and thus matrix cross-linking, to study progressive dilatation of the infrarenal abdominal aorta, including development of intraluminal thrombus. We quantified changes in biomaterial properties and biomechanical functionality within the aneurysmal segment as a function of time of enlargement and degree of thrombosis. Towards this end, we combined multi-modality imaging with state-of-the art biomechanical testing and histology to quantify regional heterogeneities for the first time and we used a computational model of arterial growth and remodeling to test multiple hypotheses, suggested by the data, regarding the degree of lost elastin, accumulation of glycosaminoglycans, and rates of collagen turnover. We found that standard histopathological findings can be misleading, while combining advanced experimental and computational methods revealed that glycosaminoglycan accumulation is pathologic, not adaptive, and that heightened collagen deposition is ineffective if not cross-linked. In conclusion, loss of elastic fiber integrity can be a strong initiator of aortic aneurysms, but it is the rate and effectiveness of fibrillar collagen remodeling that dictates enlargement. STATEMENT OF SIGNIFICANCE: Precise mechanisms by which abdominal aortic aneurysms enlarge remain unclear, but a recent elastase plus β-aminopropionitrile mouse model provides new insight into disease progression. As in the human condition, the aortic degeneration and adverse remodeling are highly heterogeneous in this model. Our multi-modality experiments quantify and contrast the heterogeneities in geometry and biomaterial properties, and our computational modeling shows that standard histopathology can be misleading. Neither accumulating glycosaminoglycans nor frustrated collagen synthesis slow disease progression, thus highlighting the importance of stimulating adaptive collagen remodeling to limit lesion enlargement.

Isolation and Purification of Versican and Analysis of Versican Proteolysis

Versican is a widely distributed chondroitin sulfate proteoglycan that forms large complexes with the glycosaminoglycan hyaluronan (HA). As a consequence of HA binding to its receptor CD44 and interactions of the versican C-terminal globular (G3) domain with a variety of extracellular matrix proteins, versican is a key component of well-defined networks in pericellular matrix and extracellular matrix. Versican is crucial for several developmental processes in the embryo ranging from cardiac development to digit separation, and there is an increasing interest in its roles in cancer and inflammation. Versican proteolysis by ADAMTS proteases is highly regulated, occurs at specific peptide bonds, and is relevant to several physiological and disease mechanisms. In this chapter, methods are described for the isolation and detection of intact and cleaved versican in tissues using morphologic and biochemical techniques. These, together with the methodologies for purification and analysis of recombinant versican and an N-terminal versican fragment named versikine that are provided here, are likely to facilitate further progress on the biology of versican and its proteolysis.

Context-dependent bioactivity of versican fragments

Versican (VCAN) proteolysis and the accumulation of VCAN fragments occur in many developmental and disease processes, affecting extracellular matrix (ECM) structure and cell phenotype. Little is known about the significance of proteolysis and the roles of fragments, or how this ECM remodeling affects the microenvironment and phenotype of diseased cells. G1-DPEAAE fragments promote aspects of epithelial-mesenchymal transitioning in developing and diseased cells, resulting in cell migration. Enhanced proliferation and invasion of tumor and endothelial cells is directly associated with G1 domain deposition and G1-DPEAAE localization respectively. These tumorigenic and angiogenic roles could explain the disease exacerbating effect often associated with G1-containing fragments, however, the pathogenicity of G1 fragments depends entirely upon the context. Overall, VCAN fragments promote tumorigenesis and inflammation; however, the specific cleavage site, the extent of cleavage activity and the microenvironment in which cleavage occurs collectively determine how this pleiotropic molecule and its fragments influence cells.

Enzymatic Degradation of Glycosaminoglycans and Proteoglycan-Mimetic Materials in Solution and on Polyelectrolyte Multilayer Surfaces

Proteoglycans (PGs) play many important roles in biology, contributing to the mechanical properties of tissues, helping to organize extracellular matrix components, and participating in signaling mechanisms related to mechanotransduction, cell differentiation, immune responses, and wound healing. Our lab has designed two different types of PG mimics: polyelectrolyte complex nanoparticles (PCNs) and PG-mimetic graft copolymers (GCs), both of which are prepared using naturally occurring glycosaminoglycans. This work evaluates the enzymatic stability of these PG mimics using hyaluronidases (I-S, IV-S, and II), chondroitinase ABC, and lysozyme, for PG mimics suspended in solution and adsorbed onto surfaces. Hyaluronan (HA)- and chondroitin sulfate (CS)-containing PG mimics are degraded by the hyaluronidases. PCNs prepared with CS and GCs prepared with heparin are the only CS- and HA-containing PG mimics protected from chondroitinase ABC. None of the materials are measurably degraded by lysozyme. Adsorption to polyelectrolyte multilayer surfaces protects PG mimics from degradation, compared to when PG mimics are combined with enzymes in solution; all surfaces are still intact after 21 days of enzyme exposure. This work reveals how the stability of PG mimics is controlled by both the composition and macromolecular assembly of the PG mimic and also by the size and specificity of the enzyme. Understanding and tuning these degradation susceptibilities are essential for advancing their applications in cardiovascular materials, orthopedic materials, and growth factor delivery applications.

Extracellular Matrix in Vascular Disease, Part 2/4: JACC Focus Seminar

Medium-sized and large arteries consist of 3 layers: the tunica intima, tunica media, and tunica adventitia. The tunica media accounts for the bulk of the vessel wall and is the chief determinant of mechanical compliance. It is primarily composed of circumferentially arranged layers of vascular smooth muscle cells that are separated by concentrically arranged elastic lamellae; a form of extracellular matrix (ECM). The tunica media is separated from the tunica intima and tunica adventitia, the innermost and outermost layers, respectively, by the internal and external elastic laminae. This second part of a 4-part JACC Focus Seminar discusses the contributions of the ECM to vascular homeostasis and pathology. Advances in genetics and proteomics approaches have fostered significant progress in our understanding of vascular ECM. This review highlights the important role of the ECM in vascular disease and the prospect of translating these discoveries into clinical disease biomarkers and potential future therapies.

TRAIL signals, extracellular matrix and vessel remodelling

The extracellular matrix (ECM) is an essential part of the vasculature, not only providing structural support to the blood vessel wall, but also in its ability to interact with cells to regulate cell phenotype and function including proliferation, migration, differentiation and death – processes important in vascular remodelling. Increasing evidence implicates TNF-related apoptosis-inducing ligand (TRAIL) signalling in the modulation of vascular cell function and remodelling under normal and pathological conditions such as in atherosclerosis. TRAIL can also stimulate synthesis of multiple ECM components within blood vessels. This review explores the relationship between TRAIL signals, the ECM, and its implications in vessel remodelling in cardiovascular disease.

Versican-A Critical Extracellular Matrix Regulator of Immunity and Inflammation

The extracellular matrix (ECM) proteoglycan, versican increases along with other ECM versican binding molecules such as hyaluronan, tumor necrosis factor stimulated gene-6 (TSG-6), and inter alpha trypsin inhibitor (IαI) during inflammation in a number of different diseases such as cardiovascular and lung disease, autoimmune diseases, and several different cancers. These interactions form stable scaffolds which can act as "landing strips" for inflammatory cells as they invade tissue from the circulation. The increase in versican is often coincident with the invasion of leukocytes early in the inflammatory process. Versican interacts with inflammatory cells either indirectly via hyaluronan or directly via receptors such as CD44, P-selectin glycoprotein ligand-1 (PSGL-1), and toll-like receptors (TLRs) present on the surface of immune and non-immune cells. These interactions activate signaling pathways that promote the synthesis and secretion of inflammatory cytokines such as TNFα, IL-6, and NFκB. Versican also influences inflammation by interacting with a variety of growth factors and cytokines involved in regulating inflammation thereby influencing their bioavailability and bioactivity. Versican is produced by multiple cell types involved in the inflammatory process. Conditional total knockout of versican in a mouse model of lung inflammation demonstrated significant reduction in leukocyte invasion into the lung and reduced inflammatory cytokine expression. While versican produced by stromal cells tends to be pro-inflammatory, versican expressed by myeloid cells can create anti-inflammatory and immunosuppressive microenvironments. Inflammation in the tumor microenvironment often contains elevated levels of versican. Perturbing the accumulation of versican in tumors can inhibit inflammation and tumor progression in some cancers. Thus versican, as a component of the ECM impacts immunity and inflammation through regulating immune cell trafficking and activation. Versican is emerging as a potential target in the control of inflammation in a number of different diseases.

Impaired exercise performance is independent of inflammation and cellular stress following genetic reduction or deletion of selenoprotein S

Selenoprotein S (Seps1) can be protective against oxidative, endoplasmic reticulum (ER), and inflammatory stress. Seps1 global knockout mice are less active, possess compromised fast muscle ex vivo strength, and, depending on context, heightened inflammation. Oxidative, ER, and inflammatory stress modulates contractile function; hence, our aim was to investigate the effects of Seps1 gene dose on exercise performance. Seps1^-/- knockout, Seps1^-/+ heterozygous, and wild-type mice were randomized to 3 days of incremental, high-intensity treadmill running or a sedentary control group. On day 4, the in situ contractile function of fast tibialis anterior (TA) muscles was determined. Seps1 reduction or deletion compromised exercise capacity, decreasing distance run. TA strength was also reduced. In sedentary Seps1^-/- knockout mice, TA fatigability was greater than wild-type mice, and this was ameliorated with exercise. Whereas, in Seps1^+/- heterozygous mice, exercise compromised TA endurance. These impairments in exercise capacity and TA contractile function were not associated with increased inflammation or a dysregulated redox state. Seps1 is highly expressed in muscle fibers and blood vessels. Interestingly, Nos1 and Vegfa mRNA transcripts were decreased in TA muscles from Seps1^-/- knockout and Seps1^-/+ heterozygous mice. Impaired exercise performance with Seps1 reduction or deletion cannot be attributed to heightened cellular stress, but it may potentially be mediated, in part, by the effects of Seps1 on the microvasculature.

New Insights into ADAMTS Metalloproteases in the Central Nervous System

Components of the extracellular matrix (ECM) are key players in regulating cellular functions throughout the whole organism. In fact, ECM components not only participate in tissue organization but also contribute to processes such as cellular maintenance, proliferation, and migration, as well as to support for various signaling pathways. In the central nervous system (CNS), proteoglycans of the lectican family, such as versican, aggrecan, brevican, and neurocan, are important constituents of the ECM. In recent years, members of this family have been found to be involved in the maintenance of CNS homeostasis and to participate directly in processes such as the organization of perineural nets, the regulation of brain plasticity, CNS development, brain injury repair, axonal guidance, and even the altering of synaptic responses. ADAMTSs are a family of “A disintegrin and metalloproteinase with thrombospondin motifs” proteins that have been found to be involved in a multitude of processes through the degradation of lecticans and other proteoglycans. Recently, alterations in ADAMTS expression and activity have been found to be involved in neuronal disorders such as stroke, neurodegeneration, schizophrenia, and even Alzheimer’s disease, which in turn may suggest their potential use as therapeutic targets. Herein, we summarize the different roles of ADAMTSs in regulating CNS events through interactions and the degradation of ECM components (more specifically, the lectican family of proteoglycans).

Accumulation of versican facilitates wound healing: Implication of its initial ADAMTS-cleavage site

Versican is a large chondroitin sulfate/dermatan sulfate proteoglycan in the extracellular matrix, and is expressed at high levels in tissues during development and remodeling in pathological conditions. Its core protein is cleaved at a region close to the N-terminal end of CSβ domain by several members of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) family, i.e., ADAMTS-1, 4, 5, 9, 15, and 20. Here, using a CRISPR/Cas9 system, we generated knock-in mice (V1R), which express an ADAMTS cleavage-resistant versican. Some V1R homozygote mice, termed R/R, exhibit syndactyly and organ hemorrhage. In wound healing experiments, R/R wound shows accumulation of versican and activated TGFβ-signaling in the early stage, leading to faster healing than wild type wound. Immunostaining for Ki67, CD31, smooth muscle α-actin, periostin demonstrates higher levels of overall cell proliferation and an increased number of endothelial cells and myofibroblasts. Immunostaining for CD11b and qRT-PCR for macrophage markers revealed increased levels of inflammatory cell infiltration, especially those of M1 macrophages. Cultured R/R dermal fibroblasts revealed increased deposition of versican, type I and III collagens, and hyaluronan, and upregulation of Smad2/3 signaling. Taken together, these results demonstrate that the cleavage site determines versican turnover and that versican plays a central role in the provisional matrix during the wound repair.

Adamts5-/- Mice Exhibit Altered Aggrecan Proteolytic Profiles That Correlate With Ascending Aortic Anomalies

OBJECTIVE

Investigate the requirement of Aggrecan (Acan) cleavage during aortic wall development in a murine model with ADAMTS (a disintegrin-like and metalloprotease domain with thrombospondin-type motifs) 5 deficiency and bicuspid aortic valves.

APPROACH

Mice with altered extracellular matrix remodeling of proteoglycans will be examined for anomalies in ascending aortic wall development. Neo-epitope antibodies that recognize ADAMTS cleaved Acan fragments will be used to investigate the mechanistic requirement of Acan turnover, in aortic wall development.

RESULTS

Adamts5-/-;Smad2+/- mice exhibited a high penetrance of aortic anomalies (n=17/17); Adamts5-/-;Smad2+/- mice with bicuspid aortic valves (7/17) showed a higher number of anomalies than Adamts5-/-;Smad2+/- mice with tricuspid aortic valves. Single mutant Adamts5-/- mice also displayed a high penetrance of aortic anomalies (n=19/19) compared with wild type (n=1/11). Aortic anomalies correlated with Acan accumulation that was apparent at the onset of elastogenesis in Adamts5-/- mice. Neo-epitope antibodies that recognize the initial amino acids in the Acan cleaved fragments neo-FREEE, neo-GLGS, and neo-SSELE were increased in the Adamts5-/- aortas compared with WT. Conversely, neo-TEGE, which recognizes highly digested Acan core fragments, was reduced in Adamts5-/- mice. However, mice containing a mutation in the TEGE373↓374ALGSV site, rendering it noncleavable, had low penetrance of aortic anomalies (n=2/4). Acan neo-DIPEN and neo-FFGVG fragments were observed in the aortic adventitia; Acan neo-FFGVG was increased abnormally in the medial layer and overlapped with smooth muscle cell loss in Adamts5-/- aortas.

CONCLUSIONS

Disruption of ADAMTS5 Acan cleavage during development correlates with ascending aortic anomalies. These data indicate that the mechanism of ADAMTS5 Acan cleavage may be critical for normal aortic wall development.

Elucidating the role of graft compliance mismatch on intimal hyperplasia using an ex vivo organ culture model

There is a growing clinical need to address high failure rates of small diameter (<6 mm) synthetic vascular grafts. Although there is a strong empirical correlation between low patency rates and low compliance of synthetic grafts, the mechanism by which compliance mismatch leads to intimal hyperplasia is poorly understood. To elucidate this relationship, synthetic vascular grafts were fabricated that varied compliance independent of other graft variables. A computational model was then used to estimate changes in fluid flow and wall shear stress as a function of graft compliance. The effect of compliance on arterial remodeling in an ex vivo organ culture model was then examined to identify early markers of intimal hyperplasia. The computational model prediction of low wall shear stress of low compliance grafts and clinical control correlated well with alterations in arterial smooth muscle cell marker, extracellular matrix, and inflammatory marker staining patterns at the distal anastomoses. Conversely, high compliance grafts displayed minimal changes in fluid flow and arterial remodeling, similar to the sham control. Overall, this work supports the intrinsic link between compliance mismatch and intimal hyperplasia and highlights the utility of this ex vivo organ culture model for rapid screening of small diameter vascular grafts. STATEMENT OF SIGNIFICANCE: We present an ex vivo organ culture model as a means to screen vascular grafts for early markers of intimal hyperplasia, a leading cause of small diameter vascular graft failure. Furthermore, a computational model was used to predict the effect of graft compliance on wall shear stress and then correlate these values to changes in arterial remodeling in the organ culture model. Combined, the ex vivo bioreactor system and computational model provide insight into the mechanistic relationship between graft-arterial compliance mismatch and the onset of intimal hyperplasia.

A role for proteoglycans in vascular disease

The content of proteoglycans (PGs) is low in the extracellular matrix (ECM) of vascular tissue, but increases dramatically in all phases of vascular disease. Early studies demonstrated that glycosaminoglycans (GAGs) including chondroitin sulfate (CS), dermatan sulfate (DS), keratan sulfate (KS) and heparan sulfate (HS) accumulate in vascular lesions in both humans and in animal models in areas of the vasculature that are susceptible to disease initiation (such as at branch points) and are frequently coincident with lipid deposits. Later studies showed the GAGs were covalently attached to specific types of core proteins that accumulate in vascular lesions. These molecules include versican (CSPG), biglycan and decorin (DS/CSPGs), lumican and fibromodulin (KSPGs) and perlecan (HSPG), although other types of PGs are present, but in lesser quantities. While the overall molecular design of these macromolecules is similar, there is tremendous structural diversity among the different PG families creating multiple forms that have selective roles in critical events that form the basis of vascular disease. PGs interact with a variety of different molecules involved in disease pathogenesis. For example, PGs bind and trap serum components that accumulate in vascular lesions such as lipoproteins, amyloid, calcium, and clotting factors. PGs interact with other ECM components and regulate, in part, ECM assembly and turnover. PGs interact with cells within the lesion and alter the phenotypes of both resident cells and cells that invade the lesion from the circulation. A number of therapeutic strategies have been developed to target specific PGs involved in key pathways that promote vascular disease. This review will provide a historical perspective of this field of research and then highlight some of the evidence that defines the involvement of PGs and their roles in the pathogenesis of vascular disease.

Versican is differentially regulated in the adventitial and medial layers of human vein grafts

Changes in extracellular matrix proteins may contribute significantly to the adaptation of vein grafts to the arterial circulation. We examined the production and distribution of versican and hyaluronan in intact human vein rings cultured ex vivo, veins perfused ex vivo, and cultured venous adventitial and smooth muscle cells. Immunohistochemistry revealed higher levels of versican in the intima/media compared to the adventitia, and no differences in hyaluronan. In the vasa vasorum, versican and hyaluronan associated with CD34⁺ progenitor cells. Culturing the vein rings for 14 days revealed increased versican immunostaining of 30–40% in all layers, with no changes in hyaluronan. Changes in versican accumulation appear to result from increased synthesis in the intima/media and decreased degradation in the adventitia as versican transcripts were increased in the intima/media, but unchanged in the adventitia, and versikine (the ADAMTS-mediated cleavage product of versican) was increased in the intima/media, but decreased in the adventitia. In perfused human veins, versican was specifically increased in the intima/media in the presence of venous pressure, but not with arterial pressure. Unexpectedly, cultured adventitial cells express and accumulate more versican and hyaluronan than smooth muscle cells. These data demonstrate a differential regulation of versican and hyaluronan in human venous adventitia vs. intima/media and suggest distinct functions for these extracellular matrix macromolecules in these venous wall compartments during the adaptive response of vein grafts to the arterial circulation.

Association of ADAMTS4 and ADAMTS9 levels with cardiovascular risk in patients with primary hyperparathyroidism

PURPOSE

Primary hyperparathyroidism (PHPT) has been associated with increased incidence of morbidity and mortality of the cardiovascular system. The pathogenetic mechanisms underlying this association are still not completely clear. A disintegrin and metalloproteinase with thrombospondin-like motifs (ADAMTS) play a critical role in atherosclerosis. This study aimed to investigate the levels of ADAMTS4 and ADAMTS9 and relationship between these proteoglycanases and cardiometabolic abnormalities in PHPT.

MATERIALS AND METHODS

A case-control study was performed in a training and research hospital. Fifty-six patients with PHPT and 61 healthy volunteers were recruited. The Framingham score was used to calculate cardiovascular risk (CVR). Serum ADAMTS levels were determined by a human enzyme-linked immunoassay in all subjects.

RESULTS

The ADAMTS9 concentration was significantly higher in patients with PHPT than in the control group (p < 0.05); however, there were no significant differences in ADAMTS4 levels between the groups (p > 0.05). In ROC curve analysis, PHPT can be predicted by the use of ADAMTS9 at a cut-off value of 30.7 pg/mL (69% sensitivity, 65% specificity). CVR score was significantly increased in the PHPT than controls (p < 0.05). ADAMTS4 and ADAMTS9 levels had positive correlations with CVR score (r = 0.322, p = 0.017; r = 0.275, p = 0.044 respectively).

CONCLUSIONS

Based on the results of the present study, cardiovascular risk is increased in PHPT and associated with ADAMTS4 and ADAMTS9. Further efforts are needed to establish the function of ADAMTS proteases in both PHPT and atherosclerosis.

Stromal Versican Regulates Tumor Growth by Promoting Angiogenesis

The proteoglycan versican is implicated in growth and metastases of several cancers. Here we investigated a potential contribution of stromal versican to tumor growth and angiogenesis. We initially determined versican expression by several cancer cell lines. Among these, MDA-MB231 and B16F10 had none to minimal expression in contrast to Lewis lung carcinoma (LLC). Notably, tumors arising from these cell lines had higher versican levels than the cell lines themselves suggesting a contribution from the host-derived tumor stroma. In LLC-derived tumors, both the tumor and stroma expressed versican at high levels. Thus, tumor stroma can make a significant contribution to tumor versican content. Versican localized preferentially to the vicinity of tumor vasculature and macrophages in the tumor. However, an ADAMTS protease-generated versican fragment uniquely localized to vascular endothelium. To specifically determine the impact of host/stroma-derived versican we therefore compared growth of tumors from B16F10 cells, which produced littleversican, in Vcan ^hdf/+ mice and wild-type littermates. Tumors in Vcan ^hdf/+ mice had reduced growth with a lower capillary density and accumulation of capillaries at the tumor periphery. These findings illustrate the variability of tumor cell line expression of versican, and demonstrate that versican is consistently contributed by the stromal tissue, where it contributes to tumor angiogenesis.

A Functional Variant of SMAD4 Enhances Thoracic Aortic Aneurysm and Dissection Risk through Promoting Smooth Muscle Cell Apoptosis and Proteoglycan Degradation

Recent studies indicate important roles for SMAD4 in SMCs proliferation, extracellular matrix maintenance, and blood vessel remodeling. However, the genetic effects of SMAD4 in the pathogenesis of thoracic aortic aneurysm and dissection (TAAD) are still largely unknown. Here we identified a functional variant of SMAD4 which might be involved in the pathological progression of TAAD. Five tagging SNPs of SMAD4 were genotyped in 202 TAAD cases and 400 controls using MALDI-TOF. rs12455792 CT or TT variant genotypes was associated with an significantly elevated TAAD risk (adjusted OR = 1.58, 95%CI = 1.09–2.30) under a dominant genetic model. It was located in the 5’UTR and predicted to influence transcription activity and RNA folding of SMAD4. In luciferase reporter assay, rs12455792 T allele markedly decreased luciferase activities. Accordingly, SMAD4 expression in tissues was lower in patients with CT or TT genotypes, compared with CC. Movat's pentachrome showed that rs12455792 T allele enhanced SMCs loss and fibers accumulation. With angiotensin II induction, rate of Apoptotic SMCs was significantly higher while SMAD4 silenced. Moreover, rs12455792 T allele also increased Versican degradation via ADAMTS-4. In conclusion, this variant might promote SMCs apoptosis and proteoglycans degradation, and further facilitate the progress of TAAD. Our findings identified rs12455792 as a predictor for progression of vascular media pathological changes related thoracic aortic disorders.

•

The variant on 5'UTR of SMAD4 gene significantly increased thoracic aortic aneurysm and dissection risk.

•

The variant rs12455792 reduced SMAD4 expression and influenced its effects on proteoglycans degradation, SMCs apoptosis and fiber accumulation.

•

rs1rs12455792 might be a potential therapeutic marker in vascular media pathological changes related thoracic aortic disorders.

Understanding the genetic features of thoracic aortic aneurysm and dissection can lead to precision surgery strategy. In this study, we demonstrated that SMAD4 rs12455792 is located in the transcription factor binding site and the allele change influences transcription activity and SMAD4 expression. Decrease of SMAD4 expression promotes proteoglycans degradation, vascular SMCs apoptosis and fiber accumulation, which are involved in pathological progression of TAAD. rs12455792 might be a potential therapeutic marker in vascular media pathological changes related thoracic aortic disorders.

Crosstalk Between T Lymphocytes and Lung Fibroblasts: Generation of a Hyaluronan-Enriched Extracellular Matrix Adhesive for Monocytes

In immunity and inflammation, T cells are often associated with stromal mesenchymal cells such as fibroblasts. Hyaluronan and proteins that associate with hyaluronan such as versican and tumor necrosis factor-inducible gene-6 (TSG-6) are extracellular matrix (ECM) components that promote leukocyte adhesion, accumulation, and activation. However, the factors responsible for producing this specialized ECM and its impact on inflammatory events are not well understood. In this study, we explored the role of T cells in stimulating lung fibroblasts to produce an ECM that impacts monocyte adhesion. We found that CD3/CD28-activated human CD4+ T cells when co-cultured with human lung fibroblasts stimulated the expression of mRNA for hyaluronan synthase 2 (HAS2) and decreased the expression of hyaluronidase 2 (HYAL2). This led to an increase in the deposition of hyaluronan that formed cable-like structures within the ECM. Co-culturing activated T cells with fibroblasts also led to increased expression and accumulation of TSG-6. Surprisingly, addition of activated CD4+ T cells to the fibroblasts reduced the expression of mRNA for versican, and increased the expression of enzymes that degrade versican, such as ADAMTS4 and ADAMTS9 (a disintegrin and metalloproteinase with a thrombospondin type-1 motif) leading to a decrease in versican in the ECM of the co-cultures. Furthermore, addition of human monocytes to these co-cultures resulted in elevated monocyte adhesion to the cable-like structures in the ECM when compared to controls. These results illustrate the importance of crosstalk between T cells and fibroblasts in promoting the generation of a matrix that is adhesive for monocytes. J. Cell. Biochem. 118: 2118-2130, 2017. © 2016 Wiley Periodicals, Inc.

Interplay of extracellular matrix and leukocytes in lung inflammation

During inflammation, leukocytes influx into lung compartments and interact with extracellular matrix (ECM). Two ECM components, versican and hyaluronan, increase in a range of lung diseases. The interaction of leukocytes with these ECM components controls leukocyte retention and accumulation, proliferation, migration, differentiation, and activation as part of the inflammatory phase of lung disease. In addition, bronchial epithelial cells from asthmatic children co-cultured with human lung fibroblasts generate an ECM that is adherent for monocytes/macrophages. Macrophages are present in both early and late lung inflammation. Matrix metalloproteinase 10 (MMP10) is induced in alveolar macrophages with injury and infection and modulates macrophage phenotype and their ability to degrade collagenous ECM components. Collectively, studies outlined in this review highlight the importance of specific ECM components in the regulation of inflammatory events in lung disease. The widespread involvement of these ECM components in the pathogenesis of lung inflammation make them attractive candidates for therapeutic intervention.

The impact of parathyroidectomy on serum ADAMTS1, ADAMTS4 levels, insulin resistance, and subclinical cardiovascular disease in primary hyperparathyroidism

PURPOSE

Primary hyperparathyroidism has been associated with increased incidence of morbidity and mortality of the cardiovascular system. The etiopathogenetic mechanisms underlying this association are still not completely clear. Accumulating evidence suggested that a disintegrin and metalloproteinase with thrombospondin-like motifs (ADAMTS) has a role in the development of inflammation and atherosclerosis. In this study, we aimed to determine whether there is a change in serum levels of ADAMTS1, ADAMTS4, carotid intima-media thickness, and cardiovascular risk score after the surgery and also whether there is a relationship between ADAMTS levels and cardiovascular risk score in hypercalcemic primary hyperparathyroidism patients.

METHODS

The study included the 48 consecutive newly diagnosed patients with primary hyperparathyroidism. The patients were evaluated before and six months after parathyroidectomy. The Framingham score is used to calculate cardiovascular risk. Serum ADAMTS levels were determined by a human enzyme-linked immunoassay in all subjects.

RESULTS

The fasting glucose, fasting insulin levels and HOMA values were decreased significantly in all patients after surgery compared to the pretreatment values (p < 0.05). ADAMTS1, ADAMTS4, and carotid intima-media thickness levels were significantly lower after surgical correction of primary hyperparathyroidism compared to the preoperative values (p < 0.05). cardiovascular risk score was decreased after parathyroidectomy however, the difference were not statistical significant (p > 0.05). There were statistically significant relationship between cardiovascular risk score and waist/hip ratio, calcium, LDL-cholesterol, carotid intima-media thickness, ADAMTS4 values.

CONCLUSION

Based on the results of the present study, fasting glucose, fasting insulin levels, ADAMTS1, ADAMTS4, and carotid intima-media thickness might be an additional parameters during the management of patients with primary hyperparathyroidism, since these factors might improve after surgery.

Improving endothelialization by the combined application of polyethylene glycol coated cerium oxide nanoparticles and VEGF in electrospun polyurethane scaffolds

CNPs-PEG/VEGF loaded electrospun PU scaffolds inhibit oxidative stress-induced EPC apoptosis as well as promote endothelializationin vitro.

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.

Matrix factorization reveals aging-specific co-expression gene modules in the fat and muscle tissues in nonhuman primates

Accurate identification of coherent transcriptional modules (subnetworks) in adipose and muscle tissues is important for revealing the related mechanisms and co-regulated pathways involved in the development of aging-related diseases. Here, we proposed a systematically computational approach, called ICEGM, to Identify the Co-Expression Gene Modules through a novel mathematical framework of Higher-Order Generalized Singular Value Decomposition (HO-GSVD). ICEGM was applied on the adipose, and heart and skeletal muscle tissues in old and young female African green vervet monkeys. The genes associated with the development of inflammation, cardiovascular and skeletal disorder diseases, and cancer were revealed by the ICEGM. Meanwhile, genes in the ICEGM modules were also enriched in the adipocytes, smooth muscle cells, cardiac myocytes, and immune cells. Comprehensive disease annotation and canonical pathway analysis indicated that immune cells, adipocytes, cardiomyocytes, and smooth muscle cells played a synergistic role in cardiac and physical functions in the aged monkeys by regulation of the biological processes associated with metabolism, inflammation, and atherosclerosis. In conclusion, the ICEGM provides an efficiently systematic framework for decoding the co-expression gene modules in multiple tissues. Analysis of genes in the ICEGM module yielded important insights on the cooperative role of multiple tissues in the development of diseases.

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.

Preparation of Proteoglycan Mimetic Graft Copolymers

Proteoglycans are proteins with pendant glycosaminoglycan polysaccharide side chains. The method described here enables the preparation of graft copolymers with glycosaminoglycan side chains, which mimic the structure and composition of proteoglycans. By controlling the stoichiometry, graft copolymers can be obtained with a wide range of glycosaminoglycan side-chain densities. The method presented here uses a three-step reaction mechanism to first functionalize a hyaluronic acid backbone, followed by reductive amination to couple the glycosaminoglycan side chain to the backbone, by the reducing end. Proteoglycan mimics like the ones proposed here could be used to study the structure-property relationships of proteoglycans and to introduce the biochemical and biomechanical properties of proteoglycans into biomaterials and therapeutic formulations.

Correlation of Versican Expression, Accumulation, and Degradation during Embryonic Development by Quantitative Immunohistochemistry

Versican, a chondroitin sulfate proteoglycan, is important in embryonic development, and disruption of the versican gene is embryonically lethal in the mouse. Although several studies show that versican is increased in various organs during development, a focused quantitative study on versican expression and distribution during lung and central nervous system development in the mouse has not previously been performed. We tracked changes in versican (Vcan) gene expression and in the accumulation and degradation of versican. Vcan expression and quantitative immunohistochemistry performed from embryonic day (E) 11.5 to E15.5 showed peak Vcan expression at E13.5 in the lungs and brain. Quantitative mRNA analysis and versican immunohistochemistry showed differences in the expression of the versican isoforms in the embryonic lung and head. The expression of Vcan mRNA and accumulation of versican in tissues was complementary. Immunohistochemistry demonstrated co-localization of versican accumulation and degradation, suggesting distinct roles of versican deposition and degradation in embryogenesis. Very little versican mRNA or protein was found in the lungs of 12- to 16-week-old mice but versican accumulation was significantly increased in mice with Pseudomonas aeruginosa lung infection. These data suggest that versican plays an important role in fundamental, overlapping cellular processes in lung development and infection.

Accelerated extracellular matrix turnover during exacerbations of COPD

Background

Exacerbations of chronic obstructive pulmonary disease (COPD) contribute significantly to disease progression. However, the effect on tissue structure and turnover is not well described. There is an urgent clinical need for biomarkers of disease activity associated with disease progression. Extracellular matrix (ECM) turnover reflects activity in tissues and consequently assessment of ECM turnover may serve as biomarkers of disease activity. We hypothesized that the turnover of lung ECM proteins were altered during exacerbations of COPD.

Methods

69 patients with COPD hospitalised for an exacerbation were recruited at admission and returned for a 4 weeks follow-up. Competitive ELISAs measuring circulating protein fragments in serum or plasma assessed the formation and degradation of collagen types III (Pro-C3 and C3M, respectively), IV (P4NP 7S and C4M, respectively), and VI (Pro-C6 and C6M, respectively), and degradation of elastin (ELM7 and EL-NE) and versican (VCANM).

Results

Circulating levels of C3M, C4M, C6M, ELM7, and EL-NE were elevated during an exacerbation of COPD as compared to follow-up (all P <0.0001), while VCANM levels were decreased (P <0.0001). Pro-C6 levels were decreased and P4NP 7S levels were elevated during exacerbation (P <0.0001). Pro-C3 levels were unchanged. At time of exacerbation, degradation/formation ratios were increased for collagen types III and VI and decreased for collagen type IV.

Conclusions

Exacerbations of COPD resulted in elevated levels of circulating fragments of structural proteins, which may serve as markers of disease activity. This suggests that patients with COPD have accelerated ECM turnover during exacerbations which may be related to disease progression.

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.

Isolation and purification of versican and analysis of versican proteolysis

Versican is a widely distributed chondroitin sulfate proteoglycan that forms large complexes with the glycosaminoglycan hyaluronan (HA). As a consequence of HA binding to its receptor CD44 and interactions of the versican C-terminal globular (G3) domain with a variety of extracellular matrix proteins, versican is a key component of well-defined networks in pericellular matrix and extracellular matrix. It is crucial for several developmental processes in the embryo and there is increasing interest in its roles in cancer and inflammation. Versican proteolysis by ADAMTS proteases is highly regulated, occurs at specific peptide bonds, and is relevant to several physiological and disease mechanisms. In this chapter, methods are described for the isolation and detection of intact and cleaved versican in tissues using morphologic and biochemical techniques. These, together with the methodologies for purification and analysis of recombinant versican and a versican fragment provided here, are likely to facilitate further progress on the biology of versican and its proteolysis.

A novel association between TGFb1 and ADAMTS4 in coronary artery disease: A new potential mechanism in the progression of atherosclerosis and diabetes

Objective:

Coronary artery disease is characterized by atherosclerosis in the vessel wall. Recently, it has been thought that increasing LDL-binding capacity of subendothelial proteoglycan fragments that are formed by protease activity can be responsible for the initiation of atherosclerosis. ADAMTS4 is a member of the versican-degrading proteinases. In vitro studies demonstrated that TGFβ inhibits the expression of ADAMTS4 in macrophages. In this study, we aimed to investigate the role and association between TGFβ1 and ADAMTS4 in coronary artery disease.

Methods:

A total of 84 cases with atheroma plaque and 72 controls without plaque were analyzed. The severity of disease was determined by Gensini score. TGFβ1 gene polymorphisms were genotyped by the PCR-RFLP method. TGFβ1 and ADAMTS4 serum levels were measured by ELISA method. Statistical analyses of genotypes and their relationship with serum levels were performed by chi-square, student t test and ANOVA.

Results:

ADAMTS4 levels were higher in cases compared with controls (p<0.05). In the patient group, ADAMTS4 levels were higher than in controls and correlated with TGFβ1 serum levels (r=0.29; p<0.05) and severity of disease (r=0.20; p<0.05). The TGFβ1 gene CCA haplotype was associated with 3.3-fold increase in coronary artery disease (OR=3.26 95% CI 1.22-8.68; p<0.05). Unexpectedly, ADAMTS4 serum levels were also higher in diabetic cases (p=0.05).

Conclusion:

This study has demonstrated that ADAMTS4 may be responsible for the pathogenesis of atherosclerosis. This is the first report about the association between ADAMTS4 and TGFβ1 serum levels in the progression of atherosclerosis in CAD. Furthermore, it is seen that TGFβ1 haplotype can cause a genetic susceptibility to CAD in the Turkish population. To our knowledge, this is also the first report suggesting higher serum ADAMTS4 levels in diabetic patients.

Imbalanced expression of Vcan mRNA splice form proteins alters heart morphology and cellular protein profiles

The fundamental importance of the proteoglycan versican to early heart formation was clearly demonstrated by the Vcan null mouse called heart defect (hdf). Total absence of the Vcan gene halts heart development at a stage prior to the heart’s pulmonary/aortic outlet segment growth. This creates a problem for determining the significance of versican’s expression in the forming valve precursors and vascular wall of the pulmonary and aortic roots. This study presents data from a mouse model, Vcan^(tm1Zim), of heart defects that results from deletion of exon 7 in the Vcan gene. Loss of exon 7 prevents expression of two of the four alternative splice forms of the Vcan gene. Mice homozygous for the exon 7 deletion survive into adulthood, however, the inability to express the V2 or V0 forms of versican results in ventricular septal defects, smaller cushions/valve leaflets with diminished myocardialization and altered pulmonary and aortic outflow tracts. We correlate these phenotypic findings with a large-scale differential protein expression profiling to identify compensatory alterations in cardiac protein expression at E13.5 post coitus that result from the absence of Vcan exon 7. The Vcan^(tm1Zim) hearts show significant changes in the relative abundance of several cytoskeletal and muscle contraction proteins including some previously associated with heart disease. These alterations define a protein fingerprint that provides insight to the observed deficiencies in pre-valvular/septal cushion mesenchyme and the stability of the myocardial phenotype required for alignment of the outflow tract with the heart ventricles.

Versican and the control of inflammation

Versican is an extracellular matrix (ECM) proteoglycan that interacts with cells by binding to non-integrin and integrin receptors and to other ECM components that associate with the cell surface. Recent studies have shown also that versican interacts with myeloid and lymphoid cells promoting their adhesion and production of inflammatory cytokines. Versican is produced by stromal cells, as well as leukocytes, and is markedly increased in inflammation. Inflammatory agonists, such as double-stranded RNA mimetics (e.g., poly I:C), stimulate stromal cells, smooth muscle cells and fibroblasts, to produce fibrillar ECMs enriched in versican and hyaluronan (HA) that interact with leukocytes promoting their adhesion. Interference with the incorporation of versican into this ECM blocks monocyte adhesion and dampens the inflammatory response. Tumor cells also express elevated levels of versican which interact with myeloid cells to promote an inflammatory response, through stimulating cytokine release, and metastasis. In addition, myeloid cells, such as macrophages in tumors, synthesize versican which affects tumor cell phenotypes, inflammation, and subsequent metastasis. Versican, by binding to hyaluronan, influences T lymphocyte phenotypes and in part controls the ability of these cells to synthesize and secrete cytokines that influence the immune response. Collectively, these studies indicate that versican as an ECM molecule plays a central role in inflammation and as a result it is emerging as a potential target promising wide therapeutic benefits.

Versican and the regulation of cell phenotype in disease

BACKGROUND

Versican is an extracellular matrix (ECM) proteoglycan that is present in the pericellular environment of most tissues and increases in many different diseases. Versican interacts with cells to influence the ability of cells to proliferate, migrate, adhere and assemble an ECM.

SCOPE OF REVIEW

The structure of the versican molecule is briefly reviewed and studies highlighting those factors that promote versican synthesis and degradation and their impact on cell phenotype in disease are discussed. Particular attention is given to vascular disease, but other diseases where versican is important are covered as well, most notably different forms of cancers. Attention is given to mechanisms(s) by which versican influences cell behaviors through either direct or indirect processes. Versican produced by either stromal cells or myeloid cells can have a major impact influencing immunity and inflammation. Finally, studies controlling versican accumulation that either delay or inhibit the progression of disease will be highlighted.

MAJOR CONCLUSIONS

Versican is one component of the ECM that can influence the ability of cells to proliferate, migrate, adhere, and remodel the ECM. Targeting versican as a way to control cell phenotype offers a novel approach in the treatment of disease.

SIGNIFICANCE

ECM molecules such as versican contribute to the structural integrity of tissues and interact with cells through direct and indirect means to regulate, in part, cellular events that form the basis of disease. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

ADAMTS-1 and ADAMTS-4 levels are elevated in thoracic aortic aneurysms and dissections

BACKGROUND

ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) is a recently identified family of extracellular metalloproteinases that has been shown to participate in tissue destruction. We hypothesized that ADAMTS-1 and ADAMTS-4 expression is increased in aortic tissues from patients with thoracic aortic aneurysms and dissections.

METHODS

We examined ADAMTS-1 and ADAMTS-4 expression in human descending thoracic aortic aneurysms (n = 14), chronic descending thoracic aortic dissections (n = 16), and descending thoracic aortas from age-matched control organ donors (n = 12). In these tissues, we also evaluated the degradation of versican, a proteoglycan substrate of ADAMTS-1 and ADAMTS-4. In cultured macrophages, we examined whether ADAMTS-4 functions in macrophage infiltration by using a transwell assay.

RESULTS

ADAMTS-1 and ADAMTS-4 protein and mRNA expression was significantly higher in thoracic aortic aneurysm and dissection tissues than in control aortic tissues. Double immunofluorescence staining showed the expression of ADAMTS-1 and ADAMTS-4 in smooth muscle cells and macrophages. Consistent with the upregulation of ADAMTS-1 and ADAMTS-4 in thoracic aortic aneurysm and dissection tissues, versican was degraded significantly more in these tissues than in control aortic tissues. In cultured macrophages, transforming growth factor-β increased ADAMTS-4 protein levels and induced macrophage invasion, and the knockdown of ADAMTS-4 reduced cell invasion.

CONCLUSIONS

Increased expression of ADAMTS proteins may promote thoracic aortic aneurysm progression by degrading versican and facilitating macrophage invasion.

Distribution and processing of a disintegrin and metalloproteinase with thrombospondin motifs-4, aggrecan, versican, and hyaluronan in equine digital laminae

OBJECTIVE

To determine the expression and distribution of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), its substrates aggrecan and versican, and their binding partner hyaluronan in laminae of healthy horses.

SAMPLE

Laminae from the forelimb hooves of 8 healthy horses.

PROCEDURES

Real-time quantitative PCR assay was used for gene expression analysis. Hyaluronidase, chondroitinase, and keratanase digestion of lamina extracts combined with SDS-PAGE and western blotting were used for protein and proteoglycan analysis. Immunofluorescent and immunohistochemical staining of tissue sections were used for protein and hyaluronan localization.

RESULTS

Genes encoding ADAMTS-4, aggrecan, versican, and hyaluronan synthase II were expressed in laminae. The ADAMTS-4 was predominantly evident as a 51-kDa protein bearing a catalytic site neoepitope indicative of active enzyme and in situ activity, which was confirmed by the presence of aggrecan and versican fragments bearing ADAMTS-4 cleavage neoepitopes in laminar protein extracts. Aggrecan, versican, and hyaluronan were localized to basal epithelial cells within the secondary epidermal laminae. The ADAMTS-4 localized to these cells but was also present in some cells in the dermal laminae.

CONCLUSIONS AND CLINICAL RELEVANCE

Within digital laminae, versican exclusively and aggrecan primarily localized within basal epithelial cells and both were constitutively cleaved by ADAMTS-4, which therefore contributed to their turnover. On the basis of known properties of these proteoglycans, it is possible that they can protect the basal epithelial cells of horses from biomechanical and concussive stress.

Effects of cleavage by a disintegrin and metalloproteinase with thrombospondin motifs-4 on gene expression and protein content of versican and aggrecan in the digital laminae of horses with starch gruel-induced laminitis

OBJECTIVE

To determine whether increased gene expression of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4) in laminae of horses with starch gruel-induced laminitis was accompanied by increased enzyme activity and substrate degradation.

SAMPLE

Laminae from the forelimb hooves of 8 healthy horses and 17 horses with starch gruel-induced laminitis (6 at onset of fever, 6 at onset of Obel grade 1 lameness, and 5 at onset of Obel grade 3 lameness).

PROCEDURES

Gene expression was determined by use of cDNA and real-time quantitative PCR assay. Protein expression and processing were determined via SDS-PAGE and quantitative western blotting. Protein distribution and abundance were determined via quantitative immunofluorescent staining.

RESULTS

ADAMTS-4 gene expression was increased and that of versican decreased in laminitic laminae, compared with expression in healthy laminae. Catalytically active ADAMTS-4 also was increased in the tissue, as were ADAMTS-4-cleavage fragments of versican. Immunofluorescent analyses indicated that versican was depleted from the basal epithelia of laminae of horses at onset of Obel grade 3 lameness, compared with results for healthy laminae, and this was accompanied by regional separation of basal epithelial cells from the basement membrane. Aggrecan gene and protein expression were not significantly affected.

CONCLUSIONS AND CLINICAL RELEVANCE

Changes in gene and protein expression of ADAMTS-4 and versican in the basal epithelium of laminitic laminae indicated a fundamental change in the physiology of basal epithelial cells. This was accompanied by and may have caused detachment of these cells from the basement membrane.

[Elastin and microfibrils in vascular development and ageing: complementary or opposite roles?]

Large arteries allow the vascular system to be more than a simple route in which the blood circulates within the organism. The elastic fibers present in the wall endow these vessels with elasticity and are responsible for the smoothing of the blood pressure and flow, which are delivered discontinuously by the heart. This function is very important to ensure appropriate hemodynamics. Elastic fibers are composed of elastin (90%) and fibrillin-rich microfibrils (10%) which provide the vessels with elasticity and are also signals able to bind to relatively specific cell membrane receptors. Stimulation of the high affinity elastin receptor by elastin peptides or tropoelastin--the elastin precursor--triggers an increase in intracellular free calcium in vascular cells, especially endothelial cells, associated with attachment, migration or proliferation. Similar effects of the stimulation of endothelial cells by microfibrils or fibrillin-1 fragments, which bind to integrins, have been demonstrated. This dual function--mechanical and in signaling--makes the elastic fibers an important actor of the development and ageing processes taking place in blood vessels. An alteration of the elastin (Eln) or fibrillin (Fbn) gene products leads to severe genetic pathologies of the cardiovascular system, such as supravalvular aortic stenosis, or Williams Beuren syndrome--in which elastin deficiency induces aortic stenoses--or Marfan syndrome, in which on the contrary fibrillin-1 deficiency promotes the appearance of aortic aneurysms. Genetically-engineered mouse models of these pathologies (such as Eln+/- mice and Fbn-1+/mgΔ mice, Eln+/-Fbn-1+/- mice) have permitted a better understanding of the pathogenesis of these syndromes. In particular, it has been shown that elastin and fibrillin-1 roles can be complementary in some aspects, while they can be opposed in some other situations. For instance, the double heterozygosity in elastin and fibrillin-1 leads to increased arterial wall stress--compared to the level induced by one of these two deficiencies alone--while the decrease in diameter induced by Eln deficiency is partly compensated by an additional deficiency in Fbn-1. Also, it is now clear that early modifications of elastin or fibrillin-1 availability can alter the normal signaling action of these proteins and lead to long term modifications of the vascular physiology and ageing processes.

Proteoglycan degradation by the ADAMTS family of proteinases

Proteoglycans are key components of extracellular matrices, providing structural support as well as influencing cellular behaviour in physiological and pathological processes. The diversity of proteoglycan function reported in the literature is equally matched by diversity in proteoglycan structure. Members of the ADAMTS (A Disintegrin And Metalloproteinase with ThromboSpondin motifs) family of enzymes degrade proteoglycans and thereby have the potential to alter tissue architecture and regulate cellular function. In this review, we focus on ADAMTS enzymes that degrade the lectican and small leucine-rich repeat families of proteoglycans. We discuss the known ADAMTS cleavage sites and the consequences of cleavage at these sites. We illustrate our discussion with examples from the literature in which ADAMTS proteolysis of proteoglycans makes profound changes to tissue function.

Altered versican cleavage in ADAMTS5 deficient mice; a novel etiology of myxomatous valve disease

In fetal valve maturation the mechanisms by which the relatively homogeneous proteoglycan-rich extracellular matrix (ECM) of endocardial cushions is replaced by a specialized and stratified ECM found in mature valves are not understood. Therefore, we reasoned that uncovering proteases critical for 'remodeling' the proteoglycan rich (extracellular matrix) ECM may elucidate novel mechanisms of valve development. We have determined that mice deficient in ADAMTS5, (A Disintegrin-like And Metalloprotease domain with ThromboSpondin-type 1 motifs) which we demonstrated is expressed predominantly by valvular endocardium during cardiac valve maturation, exhibited enlarged valves. ADAMTS5 deficient valves displayed a reduction in cleavage of its substrate versican, a critical cardiac proteoglycan. In vivo reduction of versican, in Adamts5(-/-) mice, achieved through Vcan heterozygosity, substantially rescued the valve anomalies. An increase in BMP2 immunolocalization, Sox9 expression and mesenchymal cell proliferation were observed in Adamts5(-/-) valve mesenchyme and correlated with expansion of the spongiosa (proteoglycan-rich) region in Adamts5(-/-) valve cusps. Furthermore, these data suggest that ECM remodeling via ADAMTS5 is required for endocardial to mesenchymal signaling in late fetal valve development. Although adult Adamts5(-/-) mice are viable they do not recover from developmental valve anomalies and have myxomatous cardiac valves with 100% penetrance. Since the accumulation of proteoglycans is a hallmark of myxomatous valve disease, based on these data we hypothesize that a lack of versican cleavage during fetal valve development may be a potential etiology of adult myxomatous valve disease.