Taurine and vitamin C modify monocyte and endothelial dysfunction in young smokers.
BACKGROUND
Endothelial dysfunction initiated by monocyte-endothelial interactions has previously been observed in many vasculopathies, including chronic cigarette smoking. Taurine, a semiessential amino acid, and vitamin C, a naturally occurring antioxidant, have previously been shown to have endothelial protective effects when exposed to proinflammatory insults. Therefore, we hypothesized that taurine and vitamin C would restore endothelial function in young smokers by modifying monocyte-endothelial interactions.


RESULTS
Endothelial-dependent vasodilatation was assessed in vivo using duplex ultrasonography, and monocyte-endothelial interactions were assessed in vitro using endothelial cell culture (human umbilical vein endothelial cells [HUVECs]) with monocyte-conditioned medium (MCM). Endothelial-dependent vasodilatation was significantly impaired in young smokers compared with nonsmokers. Pretreatment of young smokers for 5 days with 2 g/d vitamin C and, more significantly, with 1.5 g/d taurine attenuated this response. MCM taken from smokers impaired the release of nitric oxide and increased the levels of endothelin-1 release from HUVECs. When HUVECs were cultured with MCM from smokers who had been treated with taurine, the levels of nitric oxide and endothelin-1 returned toward control levels. This was attributed to an upregulation in endothelial nitric oxide synthase expression.


CONCLUSIONS
These observations suggest that taurine supplementation has a beneficial impact on macrovascular endothelial function, and an investigation of its effect on altered endothelial function in dyslipidemic states is warranted.
Fennessy
F M
FM
Department of Surgery, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin, Ireland.
Moneley
D S
DS
Wang
J H
JH
Kelly
C J
CJ
Bouchier-Hayes
D J
DJ
D000328:Adult; D001205:Ascorbic Acid / Q000494:pharmacology*; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016207:Cytokines / Q000032:analysis; D019332:Endothelin-1 / Q000096:biosynthesis; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D012907:Smoking; D013654:Taurine / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects
D017077:Culture Media, Conditioned; D016207:Cytokines; D019332:Endothelin-1; D013654:Taurine; D009569:Nitric Oxide; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D001205:Ascorbic Acid