Binding of elastin peptides to S-Gal protects the heart against ischemia/reperfusion injury by triggering the RISK pathway

Design and Synthesis of Novel Ultralong-Acting Peptides as EDP-EBP Interaction Inhibitors for Pulmonary Fibrosis Treatment

The increased remodeling of the extracellular matrix (ECM) in pulmonary fibrosis (PF) generates bioactive ECM fragments called matricryptins, which include elastin-derived peptides (EDPs). The interaction between EDPs and their receptors, including elastin-binding protein (EBP), plays a crucial role in exacerbating fibrosis. Here, we present LXJ-02 for the first time, a novel ultralong-acting inhibitor that disrupts the EDPs/EBP peptide-protein interaction, promoting macrophages to secrete matrix metalloproteinase-12 (MMP-12), and showing great promise as a stable peptide. MMP-12 has traditionally been implicated in promoting inflammation and fibrosis in various acute and chronic diseases. However, we reveal a novel role of LXJ-02 that activates the macrophage-MMP-12 axis to increase MMP-12 expression and degrade ECM components like elastin. This leads to the preventing of PF while also improving EDP-EBP interaction. LXJ-02 effectively reverses PF in mouse models with minimal side effects, holding great promise as an excellent therapeutic agent for lung fibrosis.

Synergistic activation of AMPK by AdipoR1/2 agonist and inhibitor of EDPs-EBP interaction recover NAFLD through enhancing mitochondrial function in mice

Nonalcoholic fatty liver disease (NAFLD), especially nonalcoholic steatohepatitis (NASH), is a common hepatic manifestation of metabolic syndrome. However, there are no effective therapy to treat this devastating disease. Accumulating evidence suggests that the generation of elastin-derived peptides (EDPs) and the inhibition of adiponectin receptors (AdipoR)1/2 plays essential roles in hepatic lipid metabolism and liver fibrosis. We recently reported that the AdipoR1/2 dual agonist JT003 significantly degraded the extracellular matrix (ECM) and ameliorated liver fibrosis. However, the degradation of the ECM lead to the generation of EDPs, which could further alter liver homeostasis negatively. Thus, in this study, we successfully combined AdipoR1/2 agonist JT003 with V14, which acted as an inhibitor of EDPs-EBP interaction to overcome the defect of ECM degradation. We found that combination of JT003 and V14 possessed excellent synergistic benefits on ameliorating NASH and liver fibrosis than either alone since they compensate the shortage of each other. These effects are induced by the enhancement of the mitochondrial antioxidant capacity, mitophagy, and mitochondrial biogenesis via AMPK pathway. Furthermore, specific suppression of AMPK could block the effects of the combination of JT003 and V14 on reduced oxidative stress, increased mitophagy and mitochondrial biogenesis. These positive results suggested that this administration of combination of AdipoR1/2 dual agonist and inhibitor of EDPs-EBP interaction can be recommended alternatively for an effective and promising therapeutic strategy for the treatment of NAFLD and NASH related fibrosis.

Physiological Impact of a Synthetic Elastic Protein in Arterial Diseases Related to Alterations of Elastic Fibers: Effect on the Aorta of Elastin-Haploinsufficient Male and Female Mice

Elastic fibers, made of elastin (90%) and fibrillin-rich microfibrils (10%), are the key extracellular components, which endow the arteries with elasticity. The alteration of elastic fibers leads to cardiovascular dysfunctions, as observed in elastin haploinsufficiency in mice (Eln+/-) or humans (supravalvular aortic stenosis or Williams–Beuren syndrome). In Eln+/+ and Eln+/- mice, we evaluated (arteriography, histology, qPCR, Western blots and cell cultures) the beneficial impact of treatment with a synthetic elastic protein (SEP), mimicking several domains of tropoelastin, the precursor of elastin, including hydrophobic elasticity-related domains and binding sites for elastin receptors. In the aorta or cultured aortic smooth muscle cells from these animals, SEP treatment induced a synthesis of elastin and fibrillin-1, a thickening of the aortic elastic lamellae, a decrease in wall stiffness and/or a strong trend toward a reduction in the elastic lamella disruptions in Eln+/- mice. SEP also modified collagen conformation and transcript expressions, enhanced the aorta constrictive response to phenylephrine in several animal groups, and, in female Eln+/- mice, it restored the normal vasodilatory response to acetylcholine. SEP should now be considered as a biomimetic molecule with an interesting potential for future treatments of elastin-deficient patients with altered arterial structure/function.

Matrikines as mediators of tissue remodelling

Extracellular matrix (ECM) proteins confer biomechanical properties, maintain cell phenotype and mediate tissue repair (via release of sequestered cytokines and proteases). In contrast to intracellular proteomes, where proteins are monitored and replaced over short time periods, many ECM proteins function for years (decades in humans) without replacement. The longevity of abundant ECM proteins, such as collagen I and elastin, leaves them vulnerable to damage accumulation and their host organs prone to chronic, age-related diseases. However, ECM protein fragmentation can potentially produce peptide cytokines (matrikines) which may exacerbate and/or ameliorate age- and disease-related ECM remodelling. In this review, we discuss ECM composition, function and degradation and highlight examples of endogenous matrikines. We then critically and comprehensively analyse published studies of matrix-derived peptides used as topical skin treatments, before considering the potential for improvements in the discovery and delivery of novel matrix-derived peptides to skin and internal organs. From this, we conclude that while the translational impact of matrix-derived peptide therapeutics is evident, the mechanisms of action of these peptides are poorly defined. Further, well-designed, multimodal studies are required.

The Elastin Receptor Complex: An Emerging Therapeutic Target Against Age-Related Vascular Diseases

The incidence of cardiovascular diseases is increasing worldwide with the growing aging of the population. Biological aging has major influence on the vascular tree and is associated with critical changes in the morphology and function of the arterial wall together with an extensive remodeling of the vascular extracellular matrix. Elastic fibers fragmentation and release of elastin degradation products, also known as elastin-derived peptides (EDPs), are typical hallmarks of aged conduit arteries. Along with the direct consequences of elastin fragmentation on the mechanical properties of arteries, the release of EDPs has been shown to modulate the development and/or progression of diverse vascular and metabolic diseases including atherosclerosis, thrombosis, type 2 diabetes and nonalcoholic steatohepatitis. Most of the biological effects mediated by these bioactive peptides are due to a peculiar membrane receptor called elastin receptor complex (ERC). This heterotrimeric receptor contains a peripheral protein called elastin-binding protein, the protective protein/cathepsin A, and a transmembrane sialidase, the neuraminidase-1 (NEU1). In this review, after an introductive part on the consequences of aging on the vasculature and the release of EDPs, we describe the composition of the ERC, the signaling pathways triggered by this receptor, and the current pharmacological strategies targeting ERC activation. Finally, we present and discuss new regulatory functions that have emerged over the last few years for the ERC through desialylation of membrane glycoproteins by NEU1, and its potential implication in receptor transactivation.

Elastin Structure, Synthesis, Regulatory Mechanism and Relationship With Cardiovascular Diseases

As the primary component of elastic fibers, elastin plays an important role in maintaining the elasticity and tensile ability of cardiovascular, pulmonary and many other tissues and organs. Studies have shown that elastin expression is regulated by a variety of molecules that have positive and negative regulatory effects. However, the specific mechanism is unclear. Moreover, elastin is reportedly involved in the development and progression of many cardiovascular diseases through changes in its expression and structural modifications once deposited in the extracellular matrix. This review article summarizes the role of elastin in myocardial ischemia-reperfusion, atherosclerosis, and atrial fibrillation, with emphasis on the potential molecular regulatory mechanisms.

Characterization of novel interactions with membrane NEU1 highlights new regulatory functions for the Elastin Receptor Complex in monocyte interaction with endothelial cells

BACKGROUND

Vascular aging is associated with remodeling of elastin, one of the main extracellular matrix component of the arterial wall, and production of elastin-derived peptides (EDP). These extracellular matrix degradation products have been shown to trigger biological activities through the elastin receptor complex (ERC) and data from the last decade have brought significant insights on the critical role played by its NEU1 subunit in the biological effects mediated by EDP and the ERC in vascular and metabolic diseases.

RESULTS

Using a proteomic approach, we previously identified new potential interaction partners of membrane NEU1. Here, we validated the interaction between NEU1 and the β₂ integrin in human monocytes and show that binding of EDP to the ERC leads to desialylation of β₂ integrin through NEU1. A similar action mechanism was identified in human umbilical vein endothelial cells (HUVEC) for intercellular cell adhesion molecule-1 (ICAM-1). Importantly, these effects were associated with a significant increase in monocyte adhesion to endothelial cells and monocyte transendothelial migration.

CONCLUSIONS

These results demonstrate that membrane NEU1 sialidase interacts and modulates the sialylation levels of the β₂ integrin and ICAM-1 through the ERC in monocytes and endothelial cells, respectively, and suggest that EDP and the ERC, through this newly identified common mode of action governed by NEU1, may be important regulators of circulating monocyte recruitment to inflamed vascular sites. Moreover, by its ability to interact with and to modulate the sialylation of key membrane glycoproteins through NEU1, new biological functions are anticipated for EDP and the ERC in elastin remodeling-associated disorders.

Elastic fibers: formation, function, and fate during aging and disease

Elastic fibers are extracellular components of higher vertebrates and confer elasticity and resilience to numerous tissues and organs such as large blood vessels, lungs, and skin. Their formation and maturation take place in a complex multistage process called elastogenesis. It requires interactions between very different proteins but also other molecules and leads to the deposition and crosslinking of elastin's precursor on a scaffold of fibrillin-rich microfibrils. Mature fibers are exceptionally resistant to most influences and, under healthy conditions, retain their biomechanical function over the life of the organism. However, due to their longevity, they accumulate damages during aging. These are caused by proteolytic degradation, formation of advanced glycation end products, calcification, oxidative damage, aspartic acid racemization, lipid accumulation, carbamylation, and mechanical fatigue. The resulting changes can lead to diminution or complete loss of elastic fiber function and ultimately affect morbidity and mortality. Particularly, the production of elastokines has been clearly shown to influence several life-threatening diseases. Moreover, the structure, distribution, and abundance of elastic fibers are directly or indirectly influenced by a variety of inherited pathological conditions, which mainly affect organs and tissues such as skin, lungs, or the cardiovascular system. A distinction can be made between microfibril-related inherited diseases that are the result of mutations in diverse microfibril genes and indirectly affect elastogenesis, and elastinopathies that are linked to changes in the elastin gene. This review gives an overview on the formation, structure, and function of elastic fibers and their fate over the human lifespan in health and disease.

Role of elastin peptides and elastin receptor complex in metabolic and cardiovascular diseases

The Cardiovascular Continuum describes a sequence of events from cardiovascular risk factors to end-stage heart disease. It includes conventional pathologies affecting cardiovascular functions such as hypertension, atherosclerosis or thrombosis and was traditionally considered from the metabolic point of view. This Cardiovascular Continuum, originally described by Dzau and Braunwald, was extended by O'Rourke to consider also the crucial role played by degradation of elastic fibers, occurring during aging, in the appearance of vascular stiffness, another deleterious risk factor of the continuum. However, the involvement of the elastin degradation products, named elastin-derived peptides, to the Cardiovascular Continuum progression has not been considered before. Data from our laboratory and others clearly showed that these bioactive peptides are central regulators of this continuum, thereby amplifying appearance and evolution of cardiovascular risk factors such as diabetes or hypertension, of vascular alterations such as atherothrombosis and calcification, but also nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. The Elastin Receptor Complex has been shown to be a crucial actor in these processes. We propose here the participation of these elastin-derived peptides and of the Elastin Receptor Complex in these events, and introduce a revisited Cardiovascular Continuum based on their involvement, for which elastin-based pharmacological strategies could have a strong impact in the future.

The VGVAPG Peptide Regulates the Production of Nitric Oxide Synthases and Reactive Oxygen Species in Mouse Astrocyte Cells In Vitro

The products of elastin degradation, namely elastin-derived peptides (EDPs), are detectable in the cerebrospinal fluid of healthy individuals and in patients after ischemic stroke, and their number increases with age. Depending on their concentrations, both nitric oxide (NO) and reactive oxygen species (ROS) take part either in myocardial ischemia reperfusion injury or in neurovascular protection after ischemic stroke. The aim of our study was to determine the impact of VGVAPG peptide on ROS and NO production and expression of endothelial nitric oxide synthase (eNos), inducible nitric oxide synthase (iNos) and neuronal nitric oxide synthase (nNos) in mouse cortical astrocytes in vitro. Primary astrocytes were maintained in DMEM/F12 without phenol red supplemented with 10% fetal bovine serum. The cells were exposed to rising VGVAPG peptide concentrations, and ROS and NO production was measured. After 6 h (for mRNA) and 24 (for the protein) of exposure to 10 nM and 1 µM of the peptide, expression of nNos, iNos and eNos was measured. Moreover, the Glb1 siRNA gene knockdown method and Pioglitazone, a peroxisome proliferator-activated receptor gamma (Pparγ) agonist, were applied. Our study shows that the VGVAPG peptide decreased eNos, iNos and nNos mRNA and protein expression in mouse astrocytes in vitro. The VGVAPG peptide also decreased NO production while increasing ROS production in the cells. Furthermore, silencing of the Glb1 gene reversed all effects caused by the VGVAPG peptide. However, due to the lack of sufficient data explaining the molecular mechanism of action of the VGVAPG peptide in the nervous system, more studies in this area are necessary.

Identification of CD36 as a new interaction partner of membrane NEU1: potential implication in the pro-atherogenic effects of the elastin receptor complex

In addition to its critical role in lysosomes for catabolism of sialoglycoconjugates, NEU1 is expressed at the plasma membrane and regulates a myriad of receptors by desialylation, playing a key role in many pathophysiological processes. Here, we developed a proteomic approach dedicated to the purification and identification by LC-MS/MS of plasma membrane NEU1 interaction partners in human macrophages. Already known interaction partners were identified as well as several new candidates such as the class B scavenger receptor CD36. Interaction between NEU1 and CD36 was confirmed by complementary approaches. We showed that elastin-derived peptides (EDP) desialylate CD36 and that this effect was blocked by the V14 peptide, which blocks the interaction between bioactive EDP and the elastin receptor complex (ERC). Importantly, EDP also increased the uptake of oxidized LDL by macrophages that is blocked by both the V14 peptide and the sialidase inhibitor 2-deoxy-2,3-didehydro-N-acetylneuraminic acid (DANA). These results demonstrate, for the first time, that binding of EDP to the ERC indirectly modulates CD36 sialylation level and regulates oxidized LDL uptake through this sialidase. These effects could contribute to the previously reported proatherogenic role of EDP and add a new dimension in the regulation of biological processes through NEU1.

Matrix metalloproteinase-12 as an endogenous resolution promoting factor following myocardial infarction

Following myocardial infarction (MI), timely resolution of inflammation promotes wound healing and scar formation while limiting excessive tissue damage. Resolution promoting factors (RPFs) are agents that blunt leukocyte trafficking and inflammation, promote necrotic and apoptotic cell clearance, and stimulate scar formation. Previously identified RPFs include mediators derived from lipids (resolvins, lipoxins, protectins, and maresins), proteins (glucocorticoids, annexin A1, galectin 1, and melanocortins), or gases (CO, H₂S, and NO). Matrix metalloproteinase-12 (MMP-12; macrophage elastase) has shown promising RPF qualities in a variety of disease states. We review here the evidence that MMP-12 may serve as a novel RPF with potential therapeutic efficacy in the setting of MI.

Matrikines for therapeutic and biomedical applications

Matrikines, peptides originating from the fragmentation of extracellular matrix proteins are identified to play important role in both health and disease. They possess biological activities, much different from their parent protein. Identification of such bioactive cryptic regions in the extracellular matrix proteins has attracted the researchers all over the world in the recent decade. These bioactive peptides could find use in preparation of biomaterials and tissue engineering applications. Matrikines identified in major extracellular matrix (ECM) proteins like collagen, elastin, fibronectin, and laminin are being extensively studied for use in tissue engineering and regenerative medicine. They are identified to modulate cellular activity like cell growth, proliferation, migration and may induce apoptosis. RGD, a well-known peptide identified in fibronectin with cell adhesive property is being investigated in designing biomaterials. Collagen hexapeptide GFOGER was found to promote cell adhesion and differentiation. Laminin also possesses regions with strong cell adhesion property. Recently, cell-penetrating peptides from elastin are used as a targeted delivery system for therapeutic drugs. The continued search for cryptic sequences in the extracellular matrix proteins along with advanced peptide coupling chemistries would lead to biomaterials with improved surface properties. This review article outlines the peptides derived from extracellular matrix and some of the possible applications of these peptides in therapeutics and tissue engineering applications.

Resveratrol pretreatment protects rat hearts from ischemia/reperfusion injury partly via a NALP3 inflammasome pathway

Inflammatory responses are key players in myocardial ischemia/reperfusion (I/R) injury. Our previous studies showed that resveratrol alleviated I/R injury in myocardial I/R animal models, but whether the NALP3 inflammasome pathway contributes to the mechanisms remains to be elucidated. In this study, we explored the modulation effect of resveratrol on myocardial I/R-induced inflammatory responses in rats. Myocardial I/R rat animal models were induced by occlusion of the left anterior descending coronary arteries (LADs) for 30 min, followed by 2 h of reperfusion. Resveratrol was administered in different doses (2.5, 5, and 10 mg/kg) at the same time as the onset of reperfusion. The serum concentrations of the trinitrotoluene (TnT) and MB isoenzyme creatine kinase (CK-MB) were detected using an automatic biochemical analyzer. Myocardial ultrastructure and morphology were observed with an electron microscope and a light microscope. Myocardial ischemia and infarct sizes were evaluated using Evans blue and tetrazolium chloride (TTC) staining. The NALP3, Caspase1, interleukin 1β (IL-1β) and interleukin 18 (IL-18) mRNA levels were evaluated using RT-PCR. The NALP3 and Caspase1 protein expression levels were detected by western blotting. The IL-1β and IL-18 content in peripheral blood was measured by enzyme-linked immunosorbent assay (ELISA). The myocardial structure in myocardial ischemia reperfusion injury (MI/RI) rats was extensively damaged. After preconditioning with different concentrations of resveratrol (2.5, 5 and 10 mg/kg), the pathology and morphology were significantly improved in a dose-dependent manner. Our results showed that resveratrol treatment significantly reduced the infarct volume and myocardial fibrosis, resulting in myocardial cells that lined up in a more orderly fashion and dose-dependent decreases in TnT and CK-MB levels in the serum of the I/R rats. Resveratrol also significantly modulated mRNA and protein levels by down-regulating NALP3 and Caspase1 expression and IL-1β and IL-18 activation. These results suggest that the NALP3 inflammasome is activated during the myocardial I/R injury process and that the secretion of the inflammatory cytokines IL-1β and IL-18 mediates the cascade inflammatory response. Resveratrol may play an important role in protecting the myocardium against I/R injury in rats by inhibiting the expression and activation of the NALP3 inflammatory body. Therefore, the attenuation of the inflammatory response may be involved in the cardioprotective mechanisms of resveratrol in response to myocardial I/R injury.

The Elastin Receptor Complex: A Unique Matricellular Receptor with High Anti-tumoral Potential

Elastin, one of the longest-lived proteins, confers elasticity to tissues with high mechanical constraints. During aging or pathophysiological conditions such as cancer progression, this insoluble polymer of tropoelastin undergoes an important degradation leading to the release of bioactive elastin-derived peptides (EDPs), named elastokines. EDP exhibit several biological functions able to drive tumor development by regulating cell proliferation, invasion, survival, angiogenesis, and matrix metalloproteinase expression in various tumor and stromal cells. Although, several receptors have been suggested to bind elastokines (α_vβ₃ and α_vβ₅ integrins, galectin-3), their main receptor remains the elastin receptor complex (ERC). This heterotrimer comprises a peripheral subunit, named elastin binding protein (EBP), associated to the protective protein/cathepsin A (PPCA). The latter is bound to a membrane-associated protein called Neuraminidase-1 (Neu-1). The pro-tumoral effects of elastokines have been linked to their binding onto EBP. Additionally, Neu-1 sialidase activity is essential for their signal transduction. Consistently, EDP-EBP interaction and Neu-1 activity emerge as original anti-tumoral targets. Interestingly, besides its direct involvement in cancer progression, the ERC also regulates diabetes outcome and thrombosis, an important risk factor for cancer development and a vascular process highly increased in patients suffering from cancer. In this review, we will describe ERC and elastokines involvement in cancer development suggesting that this unique receptor would be a promising therapeutic target. We will also discuss the pharmacological concepts aiming at blocking its pro-tumoral activities. Finally, its emerging role in cancer-associated complications and pathologies such as diabetes and thrombotic events will be also considered.

Uncoupling of Elastin Complex Receptor during In Vitro Aging Is Related to Modifications in Its Intrinsic Sialidase Activity and the Subsequent Lactosylceramide Production

Degradation of elastin leads to the production of elastin-derived peptides (EDP), which exhibit several biological effects, such as cell proliferation or protease secretion. Binding of EDP on the elastin receptor complex (ERC) triggers lactosylceramide (LacCer) production and ERK1/2 activation following ERC Neu-1 subunit activation. The ability for ERC to transduce signals is lost during aging, but the mechanism involved is still unknown. In this study, we characterized an in vitro model of aging by subculturing human dermal fibroblasts. This model was used to understand the loss of EDP biological activities during aging. Our results show that ERC uncoupling does not rely on Neu-1 or PPCA mRNA or protein level changes. Furthermore, we observe that the membrane targeting of these subunits is not affected with aging. However, we evidence that Neu-1 activity and LacCer production are altered. Basal Neu-1 catalytic activity is strongly increased in aged cells. Consequently, EDP fail to promote Neu-1 catalytic activity and LacCer production in these cells. In conclusion, we propose, for the first time, an explanation for ERC uncoupling based on the age-related alterations of Neu-1 activity and LacCer production that may explain the loss of EDP-mediated effects occurring during aging.

Soluble elastin peptides in cardiovascular homeostasis: Foe or ally

Elastin peptides, also known as elastin-derived peptides or elastokines, are soluble polypeptides in blood and tissue. The blood levels of elastin peptides are usually low but can increase during cardiovascular diseases, such as atherosclerosis, aortic aneurysm and diabetes with vascular complications. Generally, elastin peptides are derived from the degradation of insoluble elastic polymers. The biological activities of elastin peptides are bidirectional, e.g., a pro-inflammatory effect on monocyte migration induction vs. a protective effect on vasodilation promotion. However, recent in vivo studies have demonstrated that elastin peptides promote the formation of atherosclerotic plaques in hypercholesterolemic mice and induce hyperglycemia and elevations in plasma lipid levels in fasted mice. More important, the detrimental effects induced by elastin peptides can be largely inhibited by genetic or pharmacological blockade of the elastin receptor complex or by neutralization of an antibody against elastin peptides. These studies indicate new therapeutic strategies for the treatment of cardiovascular diseases by targeting elastin peptide metabolism. Therefore, the goal of this review is to summarize current knowledge about elastin peptides relevant to cardiovascular pathologies to further delineate their potential application in cardiovascular disease.

Elastin-derived peptides are new regulators of thrombosis

OBJECTIVE

Elastin is the major structural extracellular matrix component of the arterial wall that provides the elastic recoil properties and resilience essential for proper vascular function. Elastin-derived peptides (EDP) originating from elastin fragmentation during vascular remodeling have been shown to play an important role in cell physiology and development of cardiovascular diseases. However, their involvement in thrombosis has been unexplored to date. In this study, we investigated the effects of EDP on (1) platelet aggregation and related signaling and (2) thrombus formation. We also characterized the mechanism by which EDP regulate thrombosis.

APPROACH AND RESULTS

We show that EDP, derived from organo-alkaline hydrolysate of bovine insoluble elastin (kappa-elastin), decrease human platelet aggregation in whole blood induced by weak and strong agonists, such as ADP, epinephrine, arachidonic acid, collagen, TRAP, and U46619. In a mouse whole blood perfusion assay over a collagen matrix, kappa-elastin and VGVAPG, the canonical peptide recognizing the elastin receptor complex, significantly decrease thrombus formation under arterial shear conditions. We confirmed these results in vivo by demonstrating that both kappa-elastin and VGVAPG significantly prolonged the time for complete arteriole occlusion in a mouse model of thrombosis and increased tail bleeding times. Finally, we demonstrate that the regulatory role of EDP on thrombosis relies on platelets that express a functional elastin receptor complex and on the ability of EDP to disrupt plasma von Willebrand factor interaction with collagen.

CONCLUSIONS

These results highlight the complex nature of the mechanisms governing thrombus formation and reveal an unsuspected regulatory role for circulating EDP in thrombosis.

Elastin-derived peptides stimulate trophoblast migration and invasion: a positive feedback loop to enhance spiral artery remodelling

Elastin breakdown in the walls of uterine spiral arteries during early pregnancy facilitates their transformation into dilated, high-flow, low-resistance channels. Elastin-derived peptides (EDP) can influence cell migration, invasion and protease activity, and so we hypothesized that EDP released during elastolysis promote extravillous trophoblast (EVT) invasion and further elastin breakdown. Treatment of the trophoblast cell line SGHPL4 with the elastin-derived matrikine VGVAPG (1 μg/ml) significantly increased total elastase activity, promoted migration in a wound healing assay and increased invasion through Matrigel-coated transwells compared with vehicle control (0.1% DMSO) or the scrambled sequence VVGPGA. Furthermore, treatment of first-trimester placental villous explants with this EDP significantly increased both the area of trophoblast outgrowth and distance of migration away from the villous tips. Primary first-trimester cytotrophoblast exposed to VGVAPG (1 μg/ml) for 30 min showed increased phosphorylation of endothelial nitric oxide synthase and activation of the mitogen activated protein kinase pathway, events also associated with tumour cell migration and invasion. These in vitro observations suggest liberation of bioactive EDP during induction of elastolysis in the uterine spiral arteries may orchestrate a positive feedback loop that promotes EVT invasion and further elastin breakdown, contributing to the process of vascular remodelling.

Electrospun elastin-like polypeptide enriched polyurethanes and their interactions with vascular smooth muscle cells

In vascular tissue, elastin is an essential extracellular matrix protein that plays an important biomechanical and biological signalling role. Native elastin is insoluble and is difficult to extract from tissues, which results in its relatively rare use for the fabrication of vascular tissue engineering scaffolds. Recombinant elastin-like polypeptide-4 (ELP4), which mimics the structure and function of native tropoelastin, represents a practical alternative to the native elastic fibre for vascular applications. In this study, electrospinning was utilized to fabricate fibrous scaffolds which were subsequently surface modified with ELP4 and used as substrates for smooth muscle cell culture. ELP4 surface modified materials demonstrated enhanced smooth muscle cell (SMC) adhesion and maintenance of cell numbers over a 1-week period relative to controls. SMCs seeded on the ELP4 surface modified materials were also shown to exhibit the cell morphology and biological markers of a contractile phenotype including a spindle-like morphology, actin filament organization and smooth muscle myosin heavy chain expression. Competitive inhibition experiments demonstrated that the elastin-laminin cell surface receptor and its affinity for the VGVAPG peptide sequence on ELP4 molecules are likely involved in the initial SMC contact with the ELP4 modified materials. Elastin-like polypeptides show promise as surface modifiers for candidate scaffolds for engineering contractile vascular tissues.

Inflammation in myocardial diseases

Inflammatory processes underlie a broad spectrum of conditions that injure the heart muscle and cause both structural and functional deficits. In this article, we address current knowledge regarding 4 common forms of myocardial inflammation: myocardial ischemia and reperfusion, sepsis, viral myocarditis, and immune rejection. Each of these pathological states has its own unique features in pathogenesis and disease evolution, but all reflect inflammatory mechanisms that are partially shared. From the point of injury to the mobilization of innate and adaptive immune responses and inflammatory amplification, the cellular and soluble mediators and mechanisms examined in this review will be discussed with a view that both beneficial and adverse consequences arise in these human conditions.

Molecular responses of choroidal endothelial cells to elastin derived peptides through the elastin-binding protein (GLB1)

PURPOSE

Neovascular AMD involves the activation of choroidal endothelial cells to increase their inflammatory and angiogenic behaviors. Elastin derived peptides (EDPs) can elicit some of these phenotypic changes in endothelial cells. This investigation was performed to follow up on those findings by determining a receptor for these peptides in the human eye as well as evaluating the effects of elevated EDPs on choroidal cells in vitro and in vivo.

METHODS

The expression of elastin receptor genes including GLB1 was analyzed using reverse transcription PCR. Migration of choroidal endothelial cells was quantified in the presence of inhibitors to different EDP binding proteins. C57BL6 mice were injected with EDPs and studied by electroretinography, transmission electron microscopy, and microarray analysis.

RESULTS

An alternatively spliced form of beta-galactosidase (GLB1) is present on human choroidal endothelial cells and acts as a receptor for EDPs. Elevated levels of circulating EDPs do not affect retinal function in the mouse, but do increase the expression and deposition of collagen IV in the RPE/choroid complex.

CONCLUSIONS

EDPs may play a role in neovascular AMD by binding to and inducing neovascular phenotypes in choroidal endothelial cells through their receptor, GLB1. These peptides also cause an increased mRNA expression and deposition of collagen IV in the RPE/choroid, which may alter diffusion properties between the retina and choriocapillaris.

Ginseng protects rodent hearts from acute myocardial ischemia-reperfusion injury through GR/ER-activated RISK pathway in an endothelial NOS-dependent mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Ginseng (Panax ginseng C.A. Meyer) is widely used in Asian communities for treating cardiovascular diseases. However, the mechanism by which it protects the myocardium in ischemia-reperfusion (I/R) injury remains unclear. In this study, we aim to investigate whether a standardized ginseng extract (RSE) protects rodent hearts against I/R injury and if glucocorticoid and/or estrogen receptor-mediated activation of Akt and Erk1/2 (the reperfusion injury salvage kinase pathway, RISK) and subsequent nitric oxide (NO) synthesis signaling are involved in this effect.

MATERIALS AND METHODS

Rats or gene-deleted mice were subjected to 30 min ischemia by occluding the left anterior descending coronary artery and 90 min reperfusion. Infarct size, serum level of creatine kinase (CK), lactate dehydrogenase (LDH), and NO, expression and phosphorylation of glucocorticoid receptor (GR), estrogen receptor (ER), phosphatidylinositol-3 kinase (PI3K), Akt, NO synthase (NOS), extracellular signal-regulated kinase (Erk) 1/2, p38, and c-Jun NH2 terminal kinases (JNK) were examined in rat or mice treated with or without RSE in the absence or presence of pharmacological inhibitors.

RESULTS

RSE significantly reduced infarct size in a dose-dependent manner and reduced the incidence of arrhythmia, increased serum NO production, reduced serum activities of creatine kinase and lactate dehydrogenase. The infarct size reduction effect of RSE was abolished by RU468 (an inhibitor of GR), tamoxifen (an inhibitor of ER), LY294002 (an inhibitor of PI3K), Akt inhibitor IV (an inhibitor of Akt protein kinase), U0126 (an inhibitor of Erk1/2) and NG-nitro-l-arginine methyl ester hydrochloride (an inhibitor of NOS), but not actinomycin D (an inhibitor of transcription process). RSE also significantly increased the activation of GR/ER, PI3K-Akt-eNOS cascades and Erk1/2 signaling in rat heart. However, RSE did not markedly reduce infarct size in endothelium NOS(-/-) mice. This differs from its effect in inducible NOS(-/-) and wild type mice, suggesting that endothelium NOS is required for the beneficial effect of RSE on the heart.

CONCLUSION

Our findings showed for the first time that RSE protects hearts subjected to acute I/R injury and the infarct size reduction effect of RSE is associated with GR and/or ER-mediated Akt and Erk1/2 activation in an endothelium NOS-dependent manner.

Extracellular signals in young and aging breast epithelial cells and possible connections to age-associated breast cancer development

Aging of human breast tissue is accompanied by certain structural and functional variations and several studies suggest a possible contribution of these changes to an aging-related breast cancer development. At the cellular level, aging of human mammary epithelial cells is associated with significant morphological and functional alterations such as an increased cell size and a reduced proliferation. Cellular senescence of HMEC cannot be explained by a single mechanism but represents an interaction of numerous extra- and intracellular events and the complexity of such orchestrating pathways is still hardly understood. Besides the contribution of reactive oxygen species and telomere dysfunction to aging, it is the aim of this mini-review, to compare distinct changes to extracellular signals by certain matrix metalloproteinases including MMP-7 and associated growth factor pathways mediated by HB-EGF activation in young and aging HMEC. Such changes can alter hormone receptor levels within aged HMEC, induce tissue fibrosis and promote epithelial-to-mesenchymal transition as a potential prerequisite for breast cancer development. Moreover, an accumulation of aging cells during the normal life span of the breast tissue may also substantially effect and interact with adjacent neighboring populations in the local microenvironment to provide optimized growth conditions which would also support neoplastic cells.

Trophoblast- and vascular smooth muscle cell-derived MMP-12 mediates elastolysis during uterine spiral artery remodeling

During the first trimester of pregnancy, the uterine spiral arteries are remodeled, creating heavily dilated conduits that lack maternal vasomotor control but allow the placenta to meet an increasing requirement for nutrients and oxygen. To effect permanent vasodilatation, the internal elastic lamina and medial elastin fibers must be degraded. In this study, we sought to identify the elastolytic proteases involved in this process. Primary first-trimester cytotrophoblasts (CTBs) derived from the placenta exhibited intracellular and membrane-associated elastase activity; membrane-associated activity was primarily attributable to matrix metalloproteinases (MMP). Indeed, Affymetrix microarray analysis and immunocytochemistry implicated MMP-12 (macrophage metalloelastase) as a key mediator of elastolysis. Cultured human aortic smooth muscle cells (HASMCs) exhibited constitutive membrane-associated elastase activity and inducible intracellular elastase activity; these cells also expressed MMP-12 protein. Moreover, a specific inhibitor of MMP-12 significantly reduced CTB- and HASMC-mediated elastolysis in vitro, to 31.7 ± 10.9% and 23.3 ± 8.7% of control levels, respectively. MMP-12 is expressed by both interstitial and endovascular trophoblasts in the first-trimester placental bed and by vascular SMCs (VSMCs) in remodeling spiral arteries. Perfusion of isolated spiral artery segments with CTB-conditioned medium stimulated MMP-12 expression in medial VSMCs. Our data support a model in which trophoblasts and VSMCs use MMP-12 cooperatively to degrade elastin during vascular remodeling in pregnancy, with the localized release of elastin peptides and CTB-derived factors amplifying elastin catabolism.

The extracellular matrix: at the center of it all

The extracellular matrix is not only a scaffold that provides support for cells, but it is also involved in cell-cell interactions, proliferation and migration. The intricate relationships among the cellular and acellular components of the heart drive proper heart development, homeostasis and recovery following pathological injury. Cardiac myocytes, fibroblasts and endothelial cells differentially express and respond to particular extracellular matrix factors that contribute to cell communication and overall cardiac function. In addition, turnover and synthesis of ECM components play an important role in cardiac function. Therefore, a better understanding of these factors and their regulation would lend insight into cardiac development and pathology, and would open doors to novel targeted pharmacologic therapies. This review highlights the importance of contributions of particular cardiac cell populations and extracellular matrix factors that are critical to the development and regulation of heart function.

Elastin peptides antagonize ceramide-induced apoptosis

Elastin peptides regulate proliferation, chemotaxis and protease expression. The aim of this work was to assess their influence on apoptosis. Human skin fibroblast cell death was induced using C(2)-ceramide in the presence or absence of elastin peptides. We show that ceramide-induced apoptosis could be blocked by elastin peptides. Using pharmacological inhibitors, we show that elastin peptide treatment leads to activation of the anti-apoptotic protein Akt that phosphorylates the pro-apoptotic protein Bad, the Foxo3a transcription factor and caspase-9. Importantly, the anti-apoptotic effects of elastin peptides were persistent in time. Our results suggest that elastin peptides could be potent cell survival factors.

Elastin-elastases and inflamm-aging

Degradation of elastin, the main amorphous component of elastic fibers, by elastases belonging to the serine, metallo, or cysteine families leads to the generation of elastin fragments, designated as elastokines in keeping with their cytokine-like properties. Generation of elastokines from one of the longest lived protein in human might represent a strong tissue repair signal. Indeed, they (1) exhibit potent chemotactic activity for leukocytes, (2) stimulate fibroblast and smooth muscle cell proliferation, and (3) display proangiogenic activity as potent as VEGF. However, continuous exposure of cells to these matrikines, through increased elastase(s) expression with age, can contribute to the formation of a chronic inflammatory state, that is, inflamm-aging. Importantly, binding of elastokines to S-Gal, their cognate receptor, proved to stimulate matrix metalloproteinase expression in normal and cancer cells. Besides, these elastin fragments can polarize lymphocytes toward a Th-1 response or induce an osteogenic response in smooth muscle cells, and arterial wall calcification. In this chapter, emphasis will be made on the contribution of elastokines on the genesis of age-related arterial wall diseases, particularly abdominal aortic aneurysms (AAAs). An elastokine theory of AAAs progression will be proposed. Age is one main risk factor of cancer incidence and development. The myriad of biological effects exerted by elastokines on stromal and inflammatory cells led us to hypothesize that they might be main actors in elaborating a favorable cancerization field in melanoma; for instance these peptides could catalyze the vertical growth phase transition in melanoma through increased expression of gelatinase A and membrane-type 1 matrix metalloproteinase.