METABOLIC SYNDROME-ASSOCIATED MURINE AORTIC WALL STIFFENING IS ASSOCIATED WITH PREMATURE ELASTIC FIBERS AGING.

Type 2 diabetes (T2D) constitutes a major public health problem, and despite prevention efforts, this pandemic disease is 'one of the deadliest diseases in the world. In 2022, 6.7 million T2D patients died prematurely from vascular complications. Indeed, diabetes increases the risk of myocardial infarction or stroke eightfold. The identification of the molecular actors involved in the occurrence of cardiovascular complications and their prevention are therefore major axes. Our hypothesis is that factors brought into play during physiological aging appear prematurely with diabetes progression. Our study focused on the aging of the extracellular matrix (ECM), a major element in the maintenance of vascular homeostasis. We characterized the morphological and functional aspects of aorta, with a focus on the collagen and elastic fibers of diabetic mice aged from 6 months to non-diabetic mice aged 6 months and 20 months. The comparison with the two non-diabetic models (young and old) highlighted an exacerbated activity of proteases, which could explain a disturbance in the collagen accumulation and an excessive degradation of elastic fibers. Moreover, the generation of circulating elastin-derived peptides reflects premature aging of the ECM. These extracellular elements contribute to the appearance of vascular rigidity, often the origin of pathologies such as hypertension and atherosclerosis. In conclusion, we show that diabetic mice aged 6 months present the same characteristics of ECM wear as those observed in mice aged 20 months. This accelerated aortic wall remodeling could then explain the early onset of cardiovascular diseases and, therefore, the premature death of DT2 patients.

Intermittent hypoxia-related alterations in vascular structure and function: a systematic review and meta-analysis of rodent data.

BACKGROUND: Obstructive sleep apnoea and the related intermittent hypoxia (IH) are widely recognised as risk factors for incident cardiovascular diseases. Numerous studies support the deleterious vascular impact of IH in rodents but an overall interpretation is challenging owing to heterogeneity in rodent species investigated and the severity and duration of IH exposure. To clarify this major issue, we conducted a systematic review and meta-analysis to quantify the impact of IH on systemic artery structure and function depending on the different IH exposure designs. METHODS: We searched PubMed, Embase and Web of Science, and included 125 articles in a meta-analysis, among them 112 using wild-type rodents and 13 using apolipoprotein E knockout (ApoE-/-) mice. We used the standardised mean difference (SMD) to compare results between studies. RESULTS: IH significantly increased mean arterial pressure (+13.90 (95% CI 11.88-15.92) mmHg), and systolic and diastolic blood pressure. Meta-regressions showed that mean arterial pressure change was associated with strain and year of publication. IH altered vasodilation in males but not in females and increased endothelin-1-induced but not phenylephrine-induced vasoconstriction. Intima-media thickness significantly increased upon IH exposure (SMD 1.10 (95% CI 0.58-1.62); absolute values +5.23 (2.81-7.84) µm). This increase was observed in mice but not in rats and was negatively associated with age. Finally, IH increased atherosclerotic plaque size in ApoE-/- mice (SMD 1.08 (95% CI 0.80-1.37)). CONCLUSIONS: Our meta-analysis established that IH, independently of other confounders, has a strong effect on vascular structure and physiology. Our findings support the interest of identifying and treating sleep apnoea in routine cardiology practice.

Inhibition of Vascular Endothelial Cadherin Cleavage Prevents Elastic Fiber Alterations and Atherosclerosis Induced by Intermittent Hypoxia in the Mouse Aorta.

Intermittent hypoxia (IH), the major feature of obstructive sleep apnea syndrome (OSAS), induces atherosclerosis and elastic fiber alterations. VE-cadherin cleavage is increased in OSAS patients and in an IH-cellular model. It is mediated by HIF-1 and Src-tyr-kinases pathways and results in endothelial hyperpermeability. Our aim was to determine whether blocking VE-cadherin cleavage in vivo could be an efficient strategy to inhibit deleterious IH-induced vascular remodeling, elastic fiber defects and atherogenesis. VE-cadherin regulation, aortic remodeling and atherosclerosis were studied in IH-exposed C57Bl/6J or ApoE-/-mice treated or not with Src-tyr-kinases inhibitors (Saracatinib/Pazopanib) or a HIF-1 inhibitor (Acriflavine). Human aortic endothelial cells were exposed to IH and treated with the same inhibitors. LDL and the monocytes transendothelium passage were measured. In vitro, IH increased transendothelium LDL and monocytes passage, and the tested inhibitors prevented these effects. In mice, IH decreased VE-cadherin expression and increased plasmatic sVE level, intima-media thickness, elastic fiber alterations and atherosclerosis, while the inhibitors prevented these in vivo effects. In vivo inhibition of HIF-1 and Src tyr kinase pathways were associated with the prevention of IH-induced elastic fiber/lamella degradation and atherogenesis, which suggests that VE-cadherin could be an important target to limit atherogenesis and progression of arterial stiffness in OSAS.

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.

VE-cadherin cleavage in sleep apnoea: new insights into intermittent hypoxia-related endothelial permeability.

BACKGROUND: Obstructive sleep apnoea (OSA) causes intermittent hypoxia that in turn induces endothelial dysfunction and atherosclerosis progression. We hypothesised that VE-cadherin cleavage, detected by its released extracellular fragment solubilised in the blood (sVE), may be an early indicator of emergent abnormal endothelial permeability. Our aim was to assess VE-cadherin cleavage in OSA patients and in in vivo and in vitro intermittent hypoxia models to decipher the cellular mechanisms and consequences. METHODS: Sera from seven healthy volunteers exposed to 14 nights of intermittent hypoxia, 43 OSA patients and 31 healthy control subjects were analysed for their sVE content. Human aortic endothelial cells (HAECs) were exposed to 6 h of intermittent hypoxia in vitro, with or without an antioxidant or inhibitors of hypoxia-inducible factor (HIF)-1, tyrosine kinases or vascular endothelial growth factor (VEGF) pathways. VE-cadherin cleavage and phosphorylation were evaluated, and endothelial permeability was assessed by measuring transendothelial electrical resistance (TEER) and fluorescein isothiocyanate (FITC)-dextran flux. RESULTS: sVE was significantly elevated in sera from healthy volunteers submitted to intermittent hypoxia and OSA patients before treatment, but conversely decreased in OSA patients after 6 months of continuous positive airway pressure treatment. OSA was the main factor accounting for sVE variations in a multivariate analysis. In in vitro experiments, cleavage and expression of VE-cadherin increased upon HAEC exposure to intermittent hypoxia. TEER decreased and FITC-dextran flux increased. These effects were reversed by all of the pharmacological inhibitors tested. CONCLUSIONS: We suggest that in OSA, intermittent hypoxia increases endothelial permeability in OSA by inducing VE-cadherin cleavage through reactive oxygen species production, and activation of HIF-1, VEGF and tyrosine kinase pathways.

Design and synthesis of new potassium channel activators derived from the ring opening of diazoxide: study of their vasodilatory effect, stimulation of elastin synthesis and inhibitory effect on insulin release.

Benzenesulfonylureas and benzenesulfonylthioureas, as well as benzenecarbonylureas and benzenecarbonylthioureas, were prepared and evaluated as myorelaxants on 30mMKCl-precontracted rat aortic rings. The most active compounds were further examined as stimulators of elastin synthesis by vascular smooth muscle cells and as inhibitors of insulin release from pancreaticß-cells. The drugs were also characterized for their effects on glycaemia in rats. Benzenesulfonylureas and benzenesulfonylthioureas did not display any myorelaxant activity on precontracted rat aortic rings. Such an effect could be attributed to their ionization at physiological pH. By contrast, almost all benzenecarbonylureas and benzenecarbonylthioureas displayed a myorelaxant activity, in particular the benzenecarbonylureas with an oxybenzyl group linked to the ortho position of the phenyl ring. The vasodilatory activity of the most active compounds was reduced when measured in the presence of 80mMKCl or in the presence of 30mM KCl and 10µM glibenclamide. Such results suggested the involvement, at least in part, of KATP channels. Preservation of a vasodilatory activity in rat aortic rings without endothelium indicated that the site of action of such molecules was located on the vascular smooth muscle cells and not on the endothelial cells. Some of the most active compounds also stimulated elastin synthesis by vascular smooth muscle cells. Lastly, most of the active vasorelaxant drugs, except 15k and 15t at high concentrations, did not exhibit marked inhibitory effects on the insulin releasing process and on glycaemia, suggesting a relative tissue selectivity of some of these compounds for the vascular smooth muscle.

A non-canonical role of ELN protects from cellular senescence by limiting iron-dependent regulation of gene expression.

The ELN gene encodes tropoelastin which is used to generate elastic fibers that insure proper tissue elasticity. Decreased amounts of elastic fibers and/or accumulation of bioactive products of their cleavage, named elastokines, are thought to contribute to aging. Cellular senescence, characterized by a stable proliferation arrest and by the senescence-associated secretory phenotype (SASP), increases with aging, fostering the onset and progression of age-related diseases and overall aging, and has so far never been linked with elastin. Here, we identified that decrease in ELN either by siRNA in normal human fibroblasts or by knockout in mouse embryonic fibroblasts results in premature senescence. Surprisingly this effect is independent of elastic fiber degradation or elastokines production, but it relies on the rapid increase in HMOX1 after ELN downregulation. Moreover, the induction of HMOX1 depends on p53 and NRF2 transcription factors, and leads to an increase in iron, further mediating ELN downregulation-induced senescence. Screening of iron-dependent DNA and histones demethylases revealed a role for histone PHF8 demethylase in mediating ELN downregulation-induced senescence. Collectively, these results unveil a role for ELN in protecting cells from cellular senescence through a non-canonical mechanism involving a ROS/HMOX1/iron accumulation/PHF8 histone demethylase pathway reprogramming gene expression towards a senescence program.

Fibrillin-1 genetic deficiency leads to pathological ageing of arteries in mice.

Fibrillin-1, the major component of extracellular microfibrils that associate with insoluble elastin in elastic fibres, is mainly synthesized during development and postnatal growth and is believed to guide elastogenesis. Mutations in the fibrillin-1 gene cause Marfan syndrome, a multisystem disorder characterized by aortic aneurysms and dissections. The recent finding that early deficiency of elastin modifies vascular ageing has raised the possibility that fibrillin-1 deficiency could also contribute to late-onset pathology of vascular remodelling. To address this question, we examined cardiovascular function in 3-week-old, 6-month-old, and 24-month-old mice that are heterozygous for a hypomorphic structural mutation of fibrillin-1 (Fbn1{+/mgΔ} mice). Our results indicate that Fbn1{+/mgΔ} mice, particularly those that are 24 months old, are slightly more hypotensive than wild-type littermates. Additionally, aneurysm and aortic insufficiency were more frequently observed in ageing Fbn1{+/mgΔ}$ mice than in the wild-type counterparts. We also noted substantial fragmentation and decreased number of elastic lamellae in the aortic wall of Fbn1{+/mgΔ} mice, which were correlated with an increase in aortic stiffness, a decrease in vasoreactivity, altered expression of elastic fibre-related genes, including fibrillin-1 and elastin, and a decrease in the relative ratio between tissue elastin and collagen. Collectively, our findings suggest that the heterozygous mgΔ mutation accelerates some aspects of vascular ageing and eventually leads to aortic manifestations resembling those of Marfan syndrome. Importantly, our data also indicate that vascular abnormalities in Fbn1{+/mgΔ} mice are opposite to those induced by elastin haploinsufficiency during ageing that affect blood pressure, vascular dimensions, and number of elastic lamellae.

Cardiac consequences of intermittent hypoxia: a matter of dose? A systematic review and meta-analysis in rodents.

AIM: Intermittent hypoxia (IH) is considered to be a major contributor to obstructive sleep apnoea-related cardiovascular consequences. The present meta-analysis aimed to assess the effects of IH on cardiac remodelling, function and infarct size after myocardial ischaemia across different rodent species and IH severities. METHODS AND RESULTS: Relevant articles from PubMed, Embase and Web of Science were screened. We performed a random effect meta-analysis to assess the effect of IH on myocardium in rodents by using standardised mean difference (SMD). Studies using rodents exposed to IH and outcomes related to cardiac remodelling, contractile function and response to myocardial ischaemia-reperfusion were included. 5217 articles were screened and 92 were included, demonstrating that IH exposure induced cardiac remodelling, characterised by cardiomyocyte hypertrophy (cross-sectional area: SMD=2.90, CI (0.82-4.98), I2=94.2%), left ventricular (LV) dilation (LV diameter: SMD=0.64, CI (0.18-1.10), I2=88.04%), interstitial fibrosis (SMD=5.37, CI (3.22-7.53), I2=94.8) and apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labelling: SMD=6.70, CI (2.96-10.44), I2=95.9). These structural changes were accompanied by a decrease in LV ejection fraction (SMD=-1.82, CI (-2.52--1.12), I2=94.22%). Importantly, most of the utilised IH protocols mimicked extremely severe hypoxic disease. Concerning infarct size, meta-regression analyses highlighted an ambivalent role of IH, depending on its severity. Indeed, IH exposure with inspiratory oxygen fraction (F IO2 ) <7% was associated with an increase in infarct size, whereas a reduced infarct size was reported for F IO2 levels above 10%. Heterogeneity between studies, small study effect and poor reporting of methods in included articles limited the robustness of the meta-analysis findings. CONCLUSION: This meta-analysis demonstrated that severe IH systematically induces cardiac remodelling and contractile dysfunction in rodents, which might trigger or aggravate chronic heart failure. Interestingly, this meta-analysis showed that, depending on stimulus severity, IH exhibits both protective and aggravating effects on infarct size after experimental ischaemia-reperfusion procedures.

Microfibrils and fibrillin-1 induce integrin-mediated signaling, proliferation and migration in human endothelial cells.

Microfibrils are macromolecular complexes associated with elastin to form elastic fibers that endow extensible tissues, such as arteries, lungs, and skin, with elasticity property. Fibrillin-1, the main component of microfibrils, is a 350-kDa glycoprotein for which genetic haploinsufficiency in humans can lead to Marfan syndrome, a severe polyfeatured pathology including aortic aneurysms and dissections. Microfibrils and fibrillin-1 fragments mediate adhesion of several cell types, including endothelial cells, while fibrillin-1 additionally triggers lung and mesangial cell migration. However, fibrillin-1-induced intracellular signaling is unknown. We have studied the signaling events induced in human umbilical venous endothelial cells (HUVECs) by aortic microfibrils as well as recombinant fibrillin-1 Arg-Gly-Asp (RGD)-containing fragments PF9 and PF14. Aortic microfibrils and PF14, not PF9, substantially and dose dependently increased HUVEC cytoplasmic and nuclear calcium levels measured using the fluorescent dye Fluo-3. This effect of PF14 was confirmed in bovine aortic endothelial cells. PF14 action in HUVECs was mediated by αvß3 and α5ß1 integrins, phospholipase-C, inosital 1,4,5-trisphosphate, and mobilization of intracellular calcium stores, whereas membrane calcium channels were not or only slightly implicated, as shown in patch-clamp experiments. Finally, PF14 enhanced endothelial cell proliferation and migration. Hence, fibrillin-1 sequences may physiologically activate endothelial cells. Genetic fibrillin-1 deficiency could alter normal endothelial signaling and, since endothelium dysfunction is an important contributor to Marfan syndrome, participate in the arterial anomalies associated with this developmental disease.

Discrete contributions of elastic fiber components to arterial development and mechanical compliance.

OBJECTIVE: Even though elastin and fibrillin-1 are the major structural components of elastic fibers, mutations in elastin and fibrillin-1 lead to narrowing of large arteries in supravalvular aortic stenosis and dilation of the ascending aorta in Marfan syndrome, respectively. A genetic approach was therefore used here to distinguish the differential contributions of elastin and fibrillin-1 to arterial development and compliance. METHODS AND RESULTS: Key parameters of cardiovascular function were compared among adult mice haploinsufficient for elastin (Eln(+/-)), fibrillin-1 (Fbn1(+/-)), or both proteins (dHet). Physiological and morphological comparisons correlate elastin haploinsufficiency with increased blood pressure and vessel length and tortuosity in dHet mice, and fibrillin-1 haploinsufficiency with increased aortic diameter in the same mutant animals. Mechanical tests confirm that elastin and fibrillin-1 impart elastic recoil and tensile strength to the aortic wall, respectively. Additional ex vivo analyses demonstrate additive and overlapping contributions of elastin and fibrillin-1 to the material properties of vascular tissues. Lastly, light and electron microscopy evidence implicates fibrillin-1 in the hypertension-promoted remodeling of the elastin-deficient aorta. CONCLUSIONS: These results demonstrate that elastin and fibrillin-1 have both differential and complementary roles in arterial wall formation and function, and advance our knowledge of the structural determinants of vascular physiology and disease.

Age-related changes of anti-elastin antibodies in senescence-accelerated mice.

BACKGROUND: Antibodies recognizing the elastin precursor tropoelastin (ATEAb) or degradation products alpha-elastin (AEAb) are found in the serum of healthy human subjects, as a part of a homeostatic mechanism which assembles new or clears altered elastin structures. Serum ATEAb (reflecting elastin synthesis) and AEAb (reflecting elastin destruction) appear to correlate with the production and breakdown of the elastic tissue, respectively. OBJECTIVE: The aim of this study was to investigate plasma levels of AEAb and ATEAb in senescence-accelerated prone (SAMP8) and senescence-accelerated resistant (SAMR1) mice, compared with imprinting control region (ICR) mice in order to evaluate their age-related changes. METHODS: The levels of AEAb and ATEAb were measured by home-made ELISA in plasma of SAMP8, SAMR1, and ICR mice, grouped according to their age (3 and 9 months) and sex. The specificity of AEAb and ATEAb activity in mouse plasma, and elastin-derived peptides (EDP) in sera of ICR mice at 3 and 9 months of age were tested by competitive ELISA. RESULTS: The specificity of AEAb and ATEAb in mouse plasma was confirmed by the competitive investigations. The levels of AEAb in the plasma of SAMR1 and SAMP8 were increased compared to the levels measured in ICR on the matched ages (p < 0.001). Age-related increase of the levels of AEAb and ATEAb was established in the 3 strains (p < 0.001). Significantly higher levels of AEAb were established in female 9-month-old mice compared to males in all strains. The ATEAb:AEAb ratio was significantly lower in the SAM compared to the ICR strain. Positive correlation was established between the levels of serum AEAb and EDP in mouse sera of ICR mice. CONCLUSION: Variations with age in the plasma levels of AEAb and ATEAb were established in SAM compared with ICR, and in SAMP8 compared with SAMR1. Our findings suggest that increased anti-elastin IgG autoantibodies could be used as a marker of aging in SAM and possibly contribute to the processes of aging. The absence of a difference between SAMP8 and SAMR1 regarding the ATEAb:AEAb ratio raises the question if SAMR1 are an appropriate control of SAMP8 in terms of the senescence of the elastic tissues.

Contribution of TRPC Channels to Intracellular Ca2 + Dyshomeostasis in Smooth Muscle From mdx Mice.

Duchenne muscular dystrophy (DMD) is an irreversible muscle disease characterized by a progressive loss of muscle function, decreased ambulation, and ultimately death as a result of cardiac or respiratory failure. DMD is caused by the lack of dystrophin, a protein that is important for membrane stability and signaling in excitable cells. Although vascular smooth muscle cells (VSMCs) dysfunction occurs in many pathological conditions, little is known about vascular smooth muscle function in DMD. We have previously shown that striated muscle cells, as well as neurons isolated from dystrophic (mdx) mice have higher intracellular Ca2+ ([Ca2+]i) and Na+ ([Na+]i) concentrations and decreased cell viability in comparison with wild type (Wt). Experiments were carried out in isolated VSMCs from mdx (a murine model of DMD) and congenic C57BL/10SnJ Wt mice. We found elevated [Ca2+]i and [Na+]i in VSMCs from mdx mice compared to Wt. Exposure to 1-oleoyl-2-acetyl-sn-glycerol (OAG), a TRPC3 and TRPC6 channel activator, induced a greater elevation of [Ca2+]i and [Na+]i in mdx than Wt VSMCs. The OAG induced increases in [Ca2+]i could be abolished by either removal of extracellular Ca2+ or by SAR7334, a blocker of TRPC3 and TRPC 6 channels in both genotypes. Mdx and Wt VSMCs were susceptible to muscle cell stretch-induced elevations of [Ca2+]i and [Na+]i which was completely inhibited by GsMTx-4, a mechanosensitive ion channel inhibitor. Western blots showed a significant upregulation of TRPC1 -3, -6 proteins in mdx VSMCs compare to age-matched Wt. The lack of dystrophin in mdx VSMCs produced a profound alteration of [Ca2+]i and [Na+]i homeostasis that appears to be mediated by TRPC channels. Moreover, we have been able to demonstrate pharmacologically that the enhanced stretch-induced elevation of intracellular [Ca2+] and concomitant cell damage in mdx VSMCs also appears to be mediated through TRPC1, -3 and -6 channel activation.

Dill Extract Induces Elastic Fiber Neosynthesis and Functional Improvement in the Ascending Aorta of Aged Mice with Reversal of Age-Dependent Cardiac Hypertrophy and Involvement of Lysyl Oxidase-Like-1.

Elastic fibers (90% elastin, 10% fibrillin-rich microfibrils) are synthesized only in early life and adolescence mainly by the vascular smooth muscle cells through the cross-linking of its soluble precursor, tropoelastin. Elastic fibers endow the large elastic arteries with resilience and elasticity. Normal vascular aging is associated with arterial remodeling and stiffening, especially due to the end of production and degradation of elastic fibers, leading to altered cardiovascular function. Several pharmacological treatments stimulate the production of elastin and elastic fibers. In particular, dill extract (DE) has been demonstrated to stimulate elastin production in vitro in dermal equivalent models and in skin fibroblasts to increase lysyl oxidase-like-1 (LOXL-1) gene expression, an enzyme contributing to tropoelastin crosslinking and elastin formation. Here, we have investigated the effects of a chronic treatment (three months) of aged male mice with DE (5% or 10% v/v, in drinking water) on the structure and function of the ascending aorta. DE treatment, especially at 10%, of aged mice protected pre-existing elastic lamellae, reactivated tropoelastin and LOXL-1 expressions, induced elastic fiber neo-synthesis, and decreased the stiffness of the aging aortic wall, probably explaining the reversal of the age-related cardiac hypertrophy also observed following the treatment. DE could thus be considered as an anti-aging product for the cardiovascular system.

The alpha-L-Rhamnose recognizing lectin site of human dermal fibroblasts functions as a signal transducer: modulation of Ca2+ fluxes and gene expression.

An alpha-l-Rhamnose specific lectin site was described on human skin keratinocytes and fibrobasts. The addition of Rhamnose-rich oligo- and polysaccharides (RROPs) to fibroblasts has been shown to stimulate cell proliferation and increase extracellular matrix biosynthesis, suggesting that this lectin site functions as a "true" receptor transmitting messages to the cell interior. It was confirmed here that addition of the Rhamnose-rich polysaccharide, RROP-1, to normal human dermal fibroblasts (NHDFs) and human endothelial cells produced a dose-dependent stimulation of the calcium-signaling pathway, inducing fast and transient increases in Ca2+ influx and intracellular free Ca2+ level. The Rhamnose-rich oligosaccharide RROP-3 as well as l-Rhamnose alone were also able to trigger similar intracellular free Ca2+ concentration increases in NHDFs. Moreover, the recording of the RROP-1-induced modification of the gene-expression profile in fibroblasts showed that this polysaccharide triggered a down-regulation of the expression of several growth factors, adhesion molecules and extracellular matrix proteins involved in pro-tumoral activity and/or fibrotic processes. These results further support the hypothesis of a receptor function for the Rhamnose-recognizing lectin site in fibroblasts. Anti-fibrotic and anti-tumoral potential of RROP-1 remains to be further explored.

Nicorandil protects ATP-sensitive potassium channels against oxidation-induced dysfunction in cardiomyocytes of aging rats.

ATP-sensitive potassium channels (K(ATP) channels) regulate vascular tone and cardiac contraction through their action on the membrane potential of smooth muscle cells and cardiomyocytes. Because aging and diseases alter K(ATP) channel activity, many pharmacological treatments aimed at improving their function, therefore cardiovascular function, have been evaluated. Nicorandil, a K(ATP) channel opener, nitric oxide donor and antioxidant, is used as a treatment of angina pectoris and induces vasodilation, blood pressure decrease and cardioprotection in aging as well as after ischemia-reperfusion. Here, using the patch-clamp technique, we have studied the effect a chronic low dose of nicorandil (0.1 mg/kg per day for 2 months), on the activity of cardiomyocyte K(ATP) channels as a function of age, in newborn, 4-, 12- and 24-month old rats. Nicorandil exerted an anti-oxidant and protective action on cardiomyocyte K(ATP) channels, especially in aged animals, leading to restoration of a normal channel activity. These findings could justify further therapeutical applications.

Effects of chronic treatment with a low dose of nicorandil on the function of the rat aorta during ageing.

1. It is known that ATP-sensitive potassium (K(ATP)) channels regulate the membrane potential of smooth muscle cells and vascular tone. Because their activity is altered during ageing, many pharmacological treatments aimed at improving K(ATP) channel and cardiovascular functions have been evaluated. Nicorandil, a K(ATP) channel opener, nitric oxide (NO) donor and anti-oxidant, induces vasodilation, decreases blood pressure and exhibits cardioprotection in ageing, as well as after ischaemia-reperfusion. 2. In the present study, using tension myography and biochemical and histological techniques, we investigated the effects of chronic (2 months) low-dose nicorandil (0.1 mg/kg per day) treatment on the function of rat aorta during ageing (in 4-, 12- and 24-month old rats). 3. The results showed that chronic nicorandil treatment significantly improves mechanical relaxation and noradrenaline-induced vasoconstriction in aged rats. At all ages, the nicorandil-induced vasodilation was primarily mediated by its NO donor group. Nicorandil treatment resulted in an additional 0.5-1 elastic lamella in the aorta and decreased total protein, collagen and elastin content in the aortic wall at all ages. However, in 4-month-old rats, nicorandil significantly increased the elastin : total protein ratio by 19%. 4. In contrast with results of previous studies that used high doses of nicorandil (i.e. 60 mg/kg per day), low-dose nicorandil treatment in the present study did not lead to a progressive desensitization to nicorandil and may be beneficial in improving arterial function in ageing or cardiovascular diseases.

Rise and fall of elastic fibers from development to aging. Consequences on arterial structure-function and therapeutical perspectives.

In the arteries of vertebrates, evolution has given rise to resilient macromolecular structures, elastin and elastic fibers, capable of sustaining an elevated blood pressure and smoothening the discontinuous blood flow and pressure generated by the heart. Elastic fibers are produced only during development and childhood, before being progressively degraded by mechanical stress and enzymatic activities during adulthood and aging. During this period, arterial elastic fiber calcification and loading of lipids also occur, all of these events conducting to arteriosclerosis. This leads to a progressive dysfunction of the large elastic arteries inducing elevated blood pressure as well as altered hemodynamics and organ perfusion, which induce more global malfunctions of the body during normal aging. Additionally, some arterial conditions occur more frequently with advancing age, such as atherosclerosis or aneurysms, which are called age-related diseases or pathological aging. The physiological or pathological degradation of elastic fibers and function of elastic arteries seemed to be rather inevitable over time. However, during the recent years, different molecules - including several ATP-dependent potassium channel openers, such as minoxidil - have been shown to re-induce elastin production and elastic fiber assembly, leading to improvements in the arterial structure and function or in organ perfusion. This review summarizes the changes in the arterial elastic fibers and structure from development until aging, and presents some of the potential pharmacotherapies leading to elastic fiber neosynthesis and arterial function improvement.

Elastin haploinsufficiency induces alternative aging processes in the aorta.

Elastin, the main component of elastic fibers, is synthesized only in early life and provides the blood vessels with their elastic properties. With aging, elastin is progressively degraded, leading to arterial enlargement, stiffening, and dysfunction. Also, elastin is a key regulator of vascular smooth muscle cell proliferation and migration during development since heterozygous mutations in its gene (Eln) are responsible for a severe obstructive vascular disease, supravalvular aortic stenosis, isolated or associated to Williams syndrome. Here, we have studied whether early elastin synthesis could also influence the aging processes, by comparing the structure and function of ascending aorta from 6- and 24-month-old Eln+/- and Eln+/+ mice. Eln+/- animals have high blood pressure and arteries with smaller diameters and more rigid walls containing additional although thinner elastic lamellas. Nevertheless, longevity of these animals is unaffected. In young adult Eln+/- mice, some features resemble vascular aging of wild-type animals: cardiac hypertrophy, loss of elasticity of the arterial wall through enhanced fragmentation of the elastic fibers, and extracellular matrix accumulation in the aortic wall, in particular in the intima. In Eln+/- animals, we also observed an age-dependent alteration of endothelial vasorelaxant function. On the contrary, Eln+/- mice were protected from several classical consequences of aging visible in aged Eln+/+ mice, such as arterial wall thickening and alteration of alpha(1)-adrenoceptor-mediated vasoconstriction. Our results suggest that early elastin expression and organization modify arterial aging through their impact on both vascular cell physiology and structure and mechanics of blood vessels.