N-acetylcysteine amide protects renal proximal tubular epithelial cells against iohexol-induced apoptosis by blocking p38 MAPK and iNOS signaling.
BACKGROUND
The pathogenesis of contrast-induced nephropathy (CIN) is still poorly understood and apoptosis via oxidative stress has been proposed as one possible mechanism. We therefore studied the apoptotic signaling mechanism in CIN and also tested whether the new antioxidant N-acetylcysteine amide (NACA) could prevent CIN.


METHODS
LLC-PK1 cells were exposed to a widely used contrast agent, iohexol (IH). Cytotoxicity was assessed with morphology and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell death was analyzed by the DNA content analysis and PARP cleavage. Protein expression was assessed with Western blotting.


RESULTS
We observed cell death with apoptotic features in a dose- and time-dependent manner. Initiation of IH-induced apoptosis was mediated by upregulation of Bax and downregulation of Bcl-2 and Mcl-1, which was preceded by p38 MAPK activation and iNOS induction. Inhibitors of p38 MAPK and iNOS partially abolished IH-induced apoptosis. Furthermore, we found pretreatment with NACA partially protected cells from IH-induced death by reverting the expression of Bcl-2, Mc1-1 and Bax expression through inhibition of p38 MAPK and iNOS pathway.


CONCLUSIONS
This study demonstrates that apoptosis occurs during CIN. Apoptosis is associated with activations of p38 MAPK and iNOS. Pretreatment with the antioxidant NACA could prevent IH-induced cell death by blocking the p38 MAPK/iNOS signaling pathway.
Gong
Xuezhong
X
Division of Pediatric Nephrology, Department of Nephrology, Shanghai Hospital of Traditional Chinese Medicine, 274 Zhijiang Middle Road, Shanghai, China. shnanshan@hotmail.com
Celsi
Gianni
G
Carlsson
Katarina
K
Norgren
Svante
S
Chen
Ming
M
D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis; D002469:Cell Separation; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D006801:Humans; D007472:Iohexol / Q000494:pharmacology*; D007668:Kidney / Q000187:drug effects* / Q000473:pathology; D007684:Kidney Tubules / Q000187:drug effects* / Q000473:pathology; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D013552:Swine; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D000975:Antioxidants; D007472:Iohexol; C487056:N-Acetylcysteinamide; D052247:Nitric Oxide Synthase Type II; D048051:p38 Mitogen-Activated Protein Kinases; D000111:Acetylcysteine