Involvement of de novo ceramide synthesis in radiocontrast-induced renal tubular cell injury

Abstract

We reported previously that various radiocontrast media cause apoptosis in porcine proximal tubular (LLC-PK(1)) cells, in which reduction in B-cell lymphoma (Bcl)-2 expression and caspase-3 activation are implicated. In the present study, we investigated a role for ceramide in radiocontrast media-induced apoptosis in renal tubular cells. LLC-PK(1) cells were exposed to radiocontrast media for 30 min, followed by incubation for 24 h in normal medium. Cell viability was assessed by 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium monosodium salt assay, while apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling stain. Immunofluorescent stains were performed using antibodies against phosphorylated Akt (pAkt) and cAMP response element binding protein (CREB) (pCREB), and ceramide. The mRNA expression and protein content of Bcl-2 were determined by reverse transcriptase-polymerase chain reaction and enzyme immunoassay, respectively. In vivo model of contrast-induced renal injury was induced in mice with unilateral renal occlusion. The cell injury induced by the nonionic radiocontrast medium ioversol was reversed by inhibiting de novo ceramide synthesis with fumonisin B(1) (FB(1)) and L-cycloserine, but not by suppressing sphingomyelin breakdown with D609. FB(1) reversed ioversol-induced decrease in the immunoreactivities of pAkt and pCREB, reduction in Bcl-2 expression and caspase-3 activation. Like ioversol, C2 ceramide and the Akt inhibitor Src homology-6 induced apoptosis by reducing pAkt and pCREB-like immunoreactivities, lowering Bcl-2 expression and enhancing caspase-3 activity. Indeed, various radiocontrast media, excluding iodixanol which showed the least nephrotoxicity, enhanced ceramide-like immunoreactivity. The role for de novo ceramide synthesis was also shown in the in vivo model of radiocontrast nephropathy. We demonstrated here for the first time that the enhancement of de novo ceramide synthesis contributes to radiocontrast nephropathy.

Demographic and clinical variables affecting mid‐ to late‐life trajectories of plasma ceramide and dihydroceramide species

“…Previous cellular studies have determined that high ceramide levels cause renal damage, for example (Itoh et al ., 2006), but few have examined specific carbon chain lengths. One study reported higher absolute values of ceramides C16:0, C22:0, and C24:0 in the kidney extracted from CD‐1 mice 2 and 18 h after ischemia–reperfusion injury (Kalhorn & Zager, 1999).…”

The Effects of the Iodinated X-Ray Contrast Media Iodixanol, Iohexol, Iopromide, and Ioversol on the Rat Kidney Epithelial Cell Line NRK 52-E

“…34 Another study by Heinrich et al 35 showed no difference in toxicity on LLC-PK 1 cells between iodixanol and iomeprol over a broad range of concentrations and incubation times. In a study by Itoh et al 36 it was shown that iotrolan reduced the cell viability (determined by WST-8 assay), whereas iodixanol did not. The two contrast media have about the same osmolality, and hence other properties than osmolality must have been responsible for the decrease in cell viability induced by iotrolan.…”

Promising novel therapy with hydrogen gas for emergency and critical care medicine

“…This leads to renal medullary hypoxia and parenchymal injury due to accelerated production of free radicals by renal tubular epithelial cells 10. As contrast medium flows through the renal tubules, it gradually becomes highly concentrated, and toxicity of the agent itself can directly damage tubular epithelial cells 11, 12, 13. Emergency investigations and treatment often require use of a contrast medium, even in patients with a high risk of CIAKI.…”