A specific role for eNOS-derived reactive oxygen species in atherosclerosis progression.
OBJECTIVE
When the availability of tetrahydrobiopterin (BH4) is deficient, endothelial nitric oxide synthase (eNOS) produces superoxide rather than NO (uncoupled eNOS). We have shown that the atherosclerotic lesion size was augmented in apolipoprotein E-deficient (ApoE-KO) mice overexpressing eNOS because of the enhanced superoxide production. In this study, we addressed the specific importance of uncoupled eNOS in atherosclerosis, and the potential mechanistic role for specific versus nonspecific antioxidant strategies in restoring eNOS coupling.


RESULTS
We crossed mice overexpressing eNOS in the endothelium (eNOS-Tg) with mice overexpressing GTP-cyclohydrolase I (GCH), the rate-limiting enzyme in BH4 synthesis, to generate ApoE-KO/eNOS-Tg/GCH-Tg mice. As a comparison, ApoE-KO/eNOS-Tg mice were treated with vitamin C. Atherosclerotic lesion formation was increased in ApoE-KO/eNOS-Tg mice compared with ApoE-KO mice. GCH overexpression in ApoE-KO/eNOS-Tg/GCH-Tg mice increased vascular BH4 levels and reduced plaque area. This reduction was associated with decreased superoxide production from uncoupled eNOS. Vitamin C treatment failed to reduce atherosclerotic lesion size in ApoE-KO/eNOS-Tg mice, despite reducing overall vascular superoxide production.


CONCLUSIONS
In contrast to vitamin C treatment, augmenting BH4 levels in the endothelium by GCH overexpression reduced the accelerated atherosclerotic lesion formation in ApoE-KO/eNOS-Tg mice, associated with a reduction of superoxide production from uncoupled eNOS.
Takaya
Tomofumi
T
Division of Cardiovascular and Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan.
Hirata
Ken-ichi
K
Yamashita
Tomoya
T
Shinohara
Masakazu
M
Sasaki
Naoto
N
Inoue
Nobutaka
N
Yada
Toyotaka
T
Goto
Masami
M
Fukatsu
Akiko
A
Hayashi
Toshio
T
Alp
Nicholas J
NJ
Channon
Keith M
KM
Yokoyama
Mitsuhiro
M
Kawashima
Seinosuke
S
D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001057:Apolipoproteins E / Q000172:deficiency; D001205:Ascorbic Acid / Q000494:pharmacology; D050197:Atherosclerosis / Q000378:metabolism / Q000503:physiopathology*; D001708:Biopterins / Q000031:analogs & derivatives* / Q000378:metabolism; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects / Q000473:pathology; D005260:Female; D006136:GTP Cyclohydrolase / Q000032:analysis / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D052250:Nitric Oxide Synthase Type III / Q000187:drug effects* / Q000378:metabolism*; D011336:Probability; D017382:Reactive Oxygen Species / Q000378:metabolism; D012680:Sensitivity and Specificity; D013481:Superoxides / Q000378:metabolism
D000975:Antioxidants; D001057:Apolipoproteins E; D017382:Reactive Oxygen Species; D013481:Superoxides; D001708:Biopterins; D052250:Nitric Oxide Synthase Type III; D006136:GTP Cyclohydrolase; C003402:sapropterin; D001205:Ascorbic Acid