Lipoic acid supplementation prevents angiotensin II-induced renal injury.
BACKGROUND
Angiotensin II (Ang II)-induced renal injury is associated with perivascular inflammation, cell proliferation, and increased superoxide production in the vascular wall. We tested whether lipoic acid, an endogenous antioxidant, protects against the Ang II-induced inflammatory response and end-organ damage.


METHODS
Light microscopy, immunohistochemistry, electrophoretic mobility shift assay, Northern blots, and high-pressure liquid chromatography (HPLC) were used in kidneys from double transgenic rats (dTGR) harboring human renin and angiotensinogen genes and normotensive Sprague Dawley (SD) rats. The effects of lipoic acid supplementation for three weeks were examined in dTGR and SD rats.


RESULTS
Lipoic acid effectively prevented Ang II-induced glomerular and vascular damage in the kidneys and completely prevented the development of albuminuria. Ang II-induced leukocyte infiltration and cell proliferation in the kidney were attenuated. The redox-sensitive transcription factors nuclear factor (kappa) B (NF-kappa B) and activator protein-1 (AP-1) in the kidneys were increased in dTGR compared with SD, and were effectively reduced. Renal glutathione levels were much higher in dTGR than in SD, while the opposite was true for cysteine levels. These results suggested increased renal glutathione oxidation in dTGR, leading to cysteine shortage. Lipoic acid partly prevented renal cysteine depletion and increased hepatic cysteine and glutathione concentrations. This effect was accompanied by increased hepatic gamma-glutamylcysteine synthetase mRNA expression.


CONCLUSIONS
Our in vivo results suggest that lipoic acid protects against Ang II-induced renal injury through anti-inflammatory/antioxidative mechanisms. The effects are associated with decreased NF-kappa B and AP-1 activation, as well as improved thiol homeostasis.
Mervaala
Eero
E
Institute of Biomedicine, Pharmacology, Biomedicum Helsinki, University of Helsinki, Finland. eero.mervaala@helsinki.fi
Finckenberg
Piet
P
Lapatto
Risto
R
Müller
Dominik N
DN
Park
Joon-Keun
JK
Dechend
Ralf
R
Ganten
Detlev
D
Vapaatalo
Heikki
H
Luft
Friedrich C
FC
D000419:Albuminuria / Q000139:chemically induced / Q000188:drug therapy / Q000276:immunology; D000804:Angiotensin II; D000818:Animals; D030801:Animals, Genetically Modified; D000975:Antioxidants / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D006332:Cardiomegaly / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects; D007668:Kidney / Q000473:pathology; D007962:Leukocytes / Q000473:pathology; D008297:Male; D009206:Myocardium / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism; D009393:Nephritis / Q000139:chemically induced / Q000276:immunology* / Q000517:prevention & control*; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D008063:Thioctic Acid / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014662:Vasoconstrictor Agents
D000975:Antioxidants; D016328:NF-kappa B; D018808:Transcription Factor AP-1; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D008063:Thioctic Acid; D005978:Glutathione