Objective: Deficiency in vitamin B12/folate (methyl donor deficiency [MDD]) produces cardiovascular outcomes during aging and fetal programming effects in newborns of MDD mothers. Whether fetal programming provokes long-term effects on aorta remains largely unknown. Approach and Results: We investigated the impact of fetal programming on ascending aorta of aged rats born from mothers subjected to MDD during gestation/lactation. We performed morphological and molecular examinations of ascending aorta in 21 days- and 400 days-aged rats with initial MDD fetal programming (initial MDD) compared with control matched rats. Initial MDD induces remodeling of ascending aorta in aged rats, with collagen deposition ( P =0.0008), decreased thickness of elastin ( P <0.0001), and 8.7-fold increase of elastin breaks ( P =0.0002). Proteomic analyses, Western blotting, and immunohistochemical examination revealed decreased expression of α-smooth muscle actin, vinculin, SM22α (smooth muscle 22α), and N-cadherin and increased expression of TGF (transforming growth factor) β1. Elastin breaks were correlated to increased neutrophil elastase ( P =0.0002), cathepsin-K ( P =0.0002), cathepsin-S ( P <0.0001), and MMP (matrix metalloproteinase) 9, and MMP2 ( P <0.0001 and P =0.02). Proximity Duolink ligation assay showed homocysteinylation of actin-associated and extracellular matrix proteins, including SM22α ( P =0.01), N-cadherin ( P =0.0008), and vinculin ( P =0.001), which was associated with elastin breaks ( P =0.002) and increased expression of MARS (methionyl-tRNA synthetase; involved in irreversible protein homocysteinylation). Furthermore, we observed an inverse relationship between elastin breaks and blood pressure (systolic, P =0.004 and diastolic, P =0.0007). Conclusions: MDD fetal programming produced altered integrity and remodeling of ascending aorta during aging and irreversible MARS-associated homocysteinylation of key proteins of extracellular matrix and elastin homeostasis. This contributes to understanding why homocysteine-lowering vitamin B supplementation fails to relieve vascular complications in adulthood.

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.

Numerous recent studies have shown that in the continuum of cardiovascular diseases, the measurement of arterial stiffness has powerful predictive value in cardiovascular risk and mortality and that this value is independent of other conventional risk factors, such as age, cholesterol levels, diabetes, smoking, or average blood pressure. Vascular stiffening is often the main cause of arterial hypertension (AHT), which is common in the presence of obesity. However, the mechanisms leading to vascular stiffening, as well as preventive factors, remain unclear. The aim of the present study was to investigate the consequences of apelin deficiency on the vascular stiffening and wall remodeling of aorta in mice. This factor freed by visceral adipose tissue, is known for its homeostasic role in lipid and vascular metabolisms, or again in inflammation. We compared the level of metabolic markers, inflammation of white adipose tissue (WAT), and aortic wall remodeling from functional and structural approaches in apelin-deficient and wild-type (WT) mice. Apelin-deficient mice were generated by knockout of the apelin gene (APL-KO). From 8 mice by groups, aortic stiffness was analyzed by pulse wave velocity measurements and by characterizations of collagen and elastic fibers. Mann–Whitney statistical test determined the significant data (p < 5%) between groups. The APL-KO mice developed inflammation, which was associated with significant remodeling of visceral WAT, such as neutrophil elastase and cathepsin S expressions. In vitro, cathepsin S activity was detected in conditioned medium prepared from adipose tissue of the APL-KO mice, and cathepsin S activity induced high fragmentations of elastic fiber of wild-type aorta, suggesting that the WAT secretome could play a major role in vascular stiffening. In vivo, remodeling of the extracellular matrix (ECM), such as collagen accumulation and elastolysis, was observed in the aortic walls of the APL-KO mice, with the latter associated with high cathepsin S activity. In addition, pulse wave velocity (PWV) and AHT were increased in the APL-KO mice. The latter could explain aortic wall remodeling in the APL-KO mice. The absence of apelin expression, particularly in WAT, modified the adipocyte secretome and facilitated remodeling of the ECM of the aortic wall. Thus, elastolysis of elastic fibers and collagen accumulation contributed to vascular stiffening and AHT. Therefore, apelin expression could be a major element to preserve vascular homeostasis.

Diabetes is a major concern of our society as it affects one person out of 11 around the world. Elastic fiber alterations due to diabetes increase the stiffness of large arteries, but the structural effects of these alterations are poorly known. To address this issue, we used synchrotron X-ray microcomputed tomography with in-line phase contrast to image in three dimensions C57Bl6J (control) and db/db (diabetic) mice with a resolution of 650 nm/voxel and a field size of 1.3 mm3. Having previously shown in younger WT and db/db mouse cohorts that elastic lamellae contain an internal supporting lattice, here we show that in older db/db mice the elastic lamellae lose this scaffold. We coupled this label-free method with automated image analysis to demonstrate that the elastic lamellae from the arterial wall are structurally altered and become 11% smoother (286,665 measurements). This alteration suggests a link between the loss of the 3D lattice-like network and the waviness of the elastic lamellae. Therefore, waviness measurement appears to be a measurable elasticity indicator and the 3D lattice-like network appears to be at the origin of the existence of this waviness. Both could be suitable indicators of the overall elasticity of the aorta.

Vascular stiffness is often the main cause of arterial hypertension and its complications including atherosclerosis, observed during obesity. However, the mechanisms leading to this rigidity or the preventing factors are misknown. We hypothesized that apelin, known for its beneficial effects on lipid, inflammatory, and vascular metabolism, could be a protective factor against vascular stiffness. We used mice deficient for the apelin gene (KO-APL) and compared with wild-type mice (WT) at the level of metabolic markers and inflammations of white adipose tissue (WAT), as well as aortic functional and anatomical parameters. KO-APL mice developed an inflammation associated with significant remodeling of WAT, in particular with the protease expressions such as neutrophil elastase or cathepsin S. From a vascular point of view, these same elastases are involved in the fragmentation of elastic fibers, explaining the increase in vascular velocity of pulse wave and arterial hypertension. Interestingly, univariate correlation analysis showed that the inflammation markers and protease expression of WAT were associated with remodeling of the vascular wall. Our results suggest that the modifications induced by the absence of apelin particularly in WAT, could facilitate the expression of elastases and the rupture of elastic fibers, necessary to maintain elastance. This discovery is fundamental because the synthesis of elastic fibers stops as of adolescence and is not renewed during the entire life of human. The preservation of these fibers is therefore critical in maintaining vascular homeostasis. Thus, Apelin could be an interesting therapeutic route to protect the premature wear of elastic fibers.