eNOS gene therapy exacerbates hepatic ischemia-reperfusion injury in diabetes: a role for eNOS uncoupling.
Previous studies indicate that endothelial nitric oxide synthase (eNOS) function is impaired in diabetes as a result of increased vascular generation of reactive oxygen species. We hypothesized that eNOS gene therapy would augment NO. bioavailability and protect against hepatic ischemia-reperfusion (I-R) injury in type 2 diabetes mellitus. We developed a transgenic (Tg) diabetic mouse in which eNOS is systemically overexpressed. We also examined the effects of hepatic eNOS adenovirus therapy in diabetic mice. Diabetic (db/db) and nondiabetic mice were subjected to hepatic I-R injury. In nondiabetic mice, genetic overexpression of eNOS (both eNOS-Tg and eNOS adenovirus) resulted in hepatoprotection. In contrast, hepatic I-R injury was significantly increased in the db/db eNOS-Tg mouse, as serum alanine aminotransaminase (ALT) levels were increased by 3.3-fold compared with diabetic controls. Similarly, eNOS adenovirus treatment resulted in a 3.2-fold increase in serum ALT levels as compared with diabetic controls. We determined that hepatic eNOS was dysfunctional in the db/db mouse and increased genetic expression of eNOS resulted in greater production of peroxynitrite. Treatment with the eNOS cofactor tetrahydrobiopterin (BH4) or the BH4 precursor sepiapterin resulted in a significant decrease in serum ALT levels following I-R injury. We present clear examples of the protective and injurious nature of NO. therapy in I-R. Our data indicate that eNOS exists in an "uncoupled" state in the setting of diabetes and that "recoupling" of the eNOS enzyme with cofactor therapy is beneficial.
Elrod
John W
JW
Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Duranski
Mark R
MR
Langston
Will
W
Greer
James J M
JJ
Tao
Ling
L
Dugas
Tammy R
TR
Kevil
Christopher G
CG
Champion
Hunter C
HC
Lefer
David J
DJ
D000818:Animals; D001682:Biological Availability; D001708:Biopterins / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000235:genetics / Q000628:therapy*; D004357:Drug Synergism; D015316:Genetic Therapy / Q000009:adverse effects*; D008099:Liver / Q000098:blood supply* / Q000378:metabolism; D008665:Metalloporphyrins / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D020030:Nitric Oxide Donors / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D009573:Nitrites / Q000494:pharmacology; D010641:Phenotype; D010766:Phosphorylation; D011622:Pterins / Q000494:pharmacology; D015427:Reperfusion Injury / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology* / Q000517:prevention & control; D012720:Severity of Illness Index; D014443:Tyrosine / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000378:metabolism
D008665:Metalloporphyrins; C502230:Mn(III) 5,10,15,20-tetrakis(N-methylpyridinium-2-yl)porphyrin; D020030:Nitric Oxide Donors; D009573:Nitrites; D011622:Pterins; D001708:Biopterins; C002744:3-nitrotyrosine; D014443:Tyrosine; C016727:sepiapterin; D052250:Nitric Oxide Synthase Type III; C003402:sapropterin