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Background: In vascular endothelial cells, cysteine metabolism by the cystathionine γ lyase (CSE), generates hydrogen sulfide–related sulfane sulfur compounds (H 2 S n ), 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 H 2 S n ) in human endothelial cells. Methods: Liquid chromatography with tandem mass spectrometry was used to identify S -sulfhydrated cysteines in endothelial cell proteins and β3 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 H 2 S n 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 β3 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 β leg. β3 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 β3 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 H 2 S n generation, impaired flow-induced dilatation, and failure to detect β3 integrin S -sulfhydration, all of which were rescued after the administration of an H 2 S n 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 H 2 S n supplementation improved vascular reactivity in humans highlighting the potential of interfering with this pathway to treat vascular disease.

In vascular endothelial cells, cysteine metabolism by the cystathionine γ lyase (CSE), generates hydrogen sulfide-related sulfane sulfur compounds (HLiquid chromatography with tandem mass spectrometry was used to identifyThree 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 HVascular disease is associated with marked changes in the

Background— Vitamin D deficiency in humans is frequent and has been associated with inflammation. The role of the active hormone 1,25-dihydroxycholecalciferol (1,25-dihydroxy-vitamin D 3 ; 1,25-VitD3) in the cardiovascular system is controversial. High doses induce vascular calcification; vitamin D 3 deficiency, however, has been linked to cardiovascular disease because the hormone has anti-inflammatory properties. We therefore hypothesized that 1,25-VitD3 promotes regeneration after vascular injury. Methods and Results— In healthy volunteers, supplementation of vitamin D 3 (4000 IU cholecalciferol per day) increased the number of circulating CD45-CD117+Sca1+Flk1+ angiogenic myeloid cells, which are thought to promote vascular regeneration. Similarly, in mice, 1,25-VitD3 (100 ng/kg per day) increased the number of angiogenic myeloid cells and promoted reendothelialization in the carotid artery injury model. In streptozotocin-induced diabetic mice, 1,25-VitD3 also promoted reendothelialization and restored the impaired angiogenesis in the femoral artery ligation model. Angiogenic myeloid cells home through the stromal cell–derived factor 1 (SDF1) receptor CXCR4. Inhibition of CXCR4 blocked 1,25-VitD3–stimulated healing, pointing to a role of SDF1. The combination of injury and 1,25-VitD3 increased SDF1 in vessels. Conditioned medium from injured, 1,25-VitD3–treated arteries elicited a chemotactic effect on angiogenic myeloid cells, which was blocked by SDF1-neutralizing antibodies. Conditional knockout of the vitamin D receptor in myeloid cells but not the endothelium or smooth muscle cells blocked the effects of 1,25-VitD3 on healing and prevented SDF1 formation. Mechanistically, 1,25-VitD3 increased hypoxia-inducible factor 1-α through binding to its promoter. Increased hypoxia-inducible factor signaling subsequently promoted SDF1 expression, as revealed by reporter assays and knockout and inhibitory strategies of hypoxia-inducible factor 1-α. Conclusions— By inducing SDF1, vitamin D 3 is a novel approach to promote vascular repair.

We thank Dr Kain for her interest in our work.1 Her letter puts our study into a larger population-based perspective and raises the general issue of whether vitamin D3 deficiency should be prevented by dietary supplementation or sunlight exposure. We agree with her statement that moderate sunlight exposure is probably not harmful. That avoiding sunlight is associated with increased mortality, however, is only a coincidental finding of unclear causality. Obviously, mood, mobility, physical activity, and other factors affect this association. We agree with Dr Kain’s statement that outdoor physical activity particularly exerts protective effects on the cardiovascular system at large, which extend far beyond the increased production of vitamin D. Nevertheless, we feel that advising patients to undertake lifestyle changes may not be sufficient …