Mapping the Endothelial Cell S-Sulfhydrome Highlights the Crucial Role of Integrin Sulfhydration in Vascular Function.

BACKGROUND: In vascular endothelial cells, cysteine metabolism by the cystathionine γ lyase (CSE), generates hydrogen sulfide-related sulfane sulfur compounds (H2Sn), that exert their biological actions via cysteine S-sulfhydration of target proteins. This study set out to map the "S-sulfhydrome" (ie, the spectrum of proteins targeted by H2Sn) in human endothelial cells. METHODS: Liquid chromatography with tandem mass spectrometry was used to identify S-sulfhydrated cysteines in endothelial cell proteins and ß3 integrin intraprotein disulfide bond rearrangement. Functional studies included endothelial cell adhesion, shear stress-induced cell alignment, blood pressure measurements, and flow-induced vasodilatation in endothelial cell-specific CSE knockout mice and in a small collective of patients with endothelial dysfunction. RESULTS: Three paired sample sets were compared: (1) native human endothelial cells isolated from plaque-free mesenteric arteries (CSE activity high) and plaque-containing carotid arteries (CSE activity low); (2) cultured human endothelial cells kept under static conditions or exposed to fluid shear stress to decrease CSE expression; and (3) cultured endothelial cells exposed to shear stress to decrease CSE expression and treated with solvent or the slow-releasing H2Sn donor, SG1002. The endothelial cell "S-sulfhydrome" consisted of 3446 individual cysteine residues in 1591 proteins. The most altered family of proteins were the integrins and focusing on ß3 integrin in detail we found that S-sulfhydration affected intraprotein disulfide bond formation and was required for the maintenance of an extended-open conformation of the ß leg. ß3 integrin S-sulfhydration was required for endothelial cell mechanotransduction in vitro as well as flow-induced dilatation in murine mesenteric arteries. In cultured cells, the loss of S-sulfhydration impaired interactions between ß3 integrin and Gα13 (guanine nucleotide-binding protein subunit α 13), resulting in the constitutive activation of RhoA (ras homolog family member A) and impaired flow-induced endothelial cell realignment. In humans with atherosclerosis, endothelial function correlated with low H2Sn generation, impaired flow-induced dilatation, and failure to detect ß3 integrin S-sulfhydration, all of which were rescued after the administration of an H2Sn supplement. CONCLUSIONS: Vascular disease is associated with marked changes in the S-sulfhydration of endothelial cell proteins involved in mediating responses to flow. Short-term H2Sn supplementation improved vascular reactivity in humans highlighting the potential of interfering with this pathway to treat vascular disease.

Rivaroxaban versus Clopidogrel for Peripheral Artery Disease: A Clinico-Economic Approach of the COMPASS Trial.

Peripheral artery disease (PAD) is the third most common manifestation of atherosclerosis after coronary artery (CAD) and cerebrovascular disease (CVD). People with PAD have plaque findings in other vascular territories as well and, thus, are at increased risk of major adverse cardiovascular or cerebrovascular events (MACCE), including myocardial infarction, and stroke. In that context, the COMPASS multicenter, randomized controlled trial showed that the risk of MACCE was significantly reduced by 24% in the rivaroxaban plus aspirin arm compared with aspirin alone (4.1% vs 5.4% respectively; HR: 0.76, 95% CI: 0.66 to 0.86). Interestingly, the rivaroxaban/aspirin arm also showed a reduction in cardiovascular death (HR: 0.78; 95% CI: 0.64-0.96]) and allcause mortality (HR: 0.82; 95% CI: 0.71-0.96) by 22% and 18%, respectively. Recently, the FDA approved the use of the dual pathway approach, rivaroxaban 2.5 mg twice daily plus aspirin 75-100mg once daily, to reduce the risk of major cardiovascular (CV) events, such as CV death, myocardial infarction and stroke, in people with CAD as well as PAD. In comparing rivaroxaban plus aspirin versus aspirin alone, a preliminary economic analysis showed that saving per patient was USD 462 for events and USD 220 for procedures with a total reduction of USD 682 per participant in the US with the combination group (rivaroxaban plus aspirin). The data from COMPASS trial suggest that low dose rivaroxaban plus aspirin may be a preferred treatment strategy in PAD patients in whom the bleeding risk is deemed to be favourable.

High-dose ascorbic acid decreases cholesterolemic factors of an atherogenic diet in guinea pigs.

BACKGROUND: The study evaluates the effect of a high supplemental dose of ascorbic acid (AA) on plasma concentrations of total cholesterol (TC), triglycerides (TG), total lipids (TL), and lipoprotein fractions high-density, very-low-density-, and low-density lipoprotein (HDL, VLDL, LDL) in guinea pigs fed with atherogenic diet. METHODS: Group I consisted of 5 normally fed guinea pigs plus a low dose of AA (1 mg/100 g/day), group II consisted of 7 guinea pigs fed with food enriched with 2% cholesterol plus a low dose of AA (1 mg/100 g/day), and group III consisted of 7 guinea pigs fed with food enriched with 2% cholesterol plus a high dose of AA (30 mg/100 g/day). Cholesterolemic factors concentrations were determined after nine weeks. RESULTS: Concentrations of TC, TG, TL, LDL, and VLDL were increased in group II compared to group I (p < 0.01 for all differences). Supplementation with a high dose of AA resulted in decreased concentrations of TC (p < 0.01), TG (p < 0.01), TL (p < 0.01), and LDL (p < 0.01) in group III compared to group II. Additionally, concentration of HDL was increased in group III compared to group II (p < 0.01). CONCLUSION: High-dose AA supplementation to an atherogenic diet decreases concentrations of TC, TG, TL, and LDL and increases concentration of HDL compared to low-dose AA.