Endothelial dysfunction in rat adjuvant-induced arthritis: vascular superoxide production by NAD(P)H oxidase and uncoupled endothelial nitric oxide synthase.
OBJECTIVE
To investigate endothelial function and levels of vascular oxidative stress in rat adjuvant-induced arthritis (AIA), in view of mounting evidence for an association between rheumatoid arthritis (RA) and accelerated vascular disease.


METHODS
Thoracic aortic rings were prepared from AIA and control rats. After preconstriction by norepinephrine, the vasodilatory response to acetylcholine was determined. The amounts of 4-hydroxy-2-nonenal (HNE) and nitrotyrosine in AIA rat aortas were measured by Western blotting. Homogenates of the aortas were incubated with various substrates for superoxide-producing enzymes, and superoxide production was assessed by fluorogenic oxidation of dihydroethidium to ethidium. Expression of endothelial nitric oxide synthase (eNOS) in aortas was examined by real-time reverse transcriptase-polymerase chain reaction and Western blotting. Serum levels of tetrahydrobiopterin (BH4), a critical eNOS cofactor, were determined by high-performance liquid chromatography.


RESULTS
Endothelium-dependent relaxation of the aortic ring was significantly depressed in AIA rats compared with control rats. The amounts of HNE and nitrotyrosine were increased in AIA rat aortas, indicating overproduction of reactive oxygen species. Incubation of AIA rat aorta homogenates with NADH or L-arginine, a substrate of eNOS, resulted in a significant increase in superoxide production. Endothelial NOS was highly expressed in AIA rat aortas. Serum levels of BH4 were significantly lower in AIA. Treatment of AIA with BH4 reversed the endothelial dysfunction, suggesting that its deficiency may contribute to the uncoupling of eNOS.


CONCLUSIONS
Vascular dysfunction in RA can be partially modeled in animals. NAD(P)H oxidase and uncoupled eNOS are responsible for the increase in vascular oxidative stress, which is likely to be involved in the endothelial dysfunction in AIA.
Haruna
Yoshisuke
Y
Kawasaki Medical School, Kurashiki, Japan.
Morita
Yoshitaka
Y
Komai
Norio
N
Yada
Toyotaka
T
Sakuta
Takeo
T
Tomita
Naruya
N
Fox
David A
DA
Kashihara
Naoki
N
D000109:Acetylcholine / Q000494:pharmacology; D000447:Aldehydes / Q000032:analysis; D000818:Animals; D001013:Aorta, Thoracic; D001169:Arthritis, Experimental / Q000378:metabolism / Q000503:physiopathology*; D001708:Biopterins / Q000031:analogs & derivatives / Q000097:blood; D004730:Endothelium, Vascular / Q000378:metabolism / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D019255:NADPH Oxidases / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D051381:Rats; D011917:Rats, Inbred Lew; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis; D014664:Vasodilation / Q000187:drug effects
D000447:Aldehydes; D017382:Reactive Oxygen Species; D013481:Superoxides; D001708:Biopterins; C002744:3-nitrotyrosine; D014443:Tyrosine; D052250:Nitric Oxide Synthase Type III; D019255:NADPH Oxidases; C003402:sapropterin; C027576:4-hydroxy-2-nonenal; D000109:Acetylcholine