Effect of Renal Ceramidase on AKI

Background: This study was designed to explore the changes of renal metabolic enzymes related to sphingolipids in AKI and to clarify the important role of ceramidase, the metabolic enzymes of sphingolipids in AKI. Methods: renal tissue of C57BL/6 mouse was taken on bilateral renal ischemia reperfusion injury (Bi-IRI) 2nd day and 28day for quantitative proteomic. Renal tissue ceramide and expression of renal tissue acid ceramidase and neutral ceramidase were performed at 6 hours, 12 hours, 18 hours, 24 hours, and 48 hours. Acid ceramidase inhibitor ARN14974, neutral ceramidase inhibitor C6-urea-ceramide, and ceramidase broad-spectrum agonist adiporon were administrated to IRI mice. Results: Among the enzymes related to ceramide synthesis, serine palmitoyltransferase 1, serine palmitoyltransferase 2, and glucose ceramidase were elevated at both IRI 2d group and IRI 28d group, and ceramide synthase 2 was mildly elevated at IRI 2d group but the change was not statistically different at IRI 28d group. β-Hexosaminidase α-subunit was mildly elevated at IRI 2d group and markedly elevated. Among the ceramide-degrading enzymes, acid ceramidase was slightly elevated at IRI 2d group and significantly elevated at IRI 28d group, and neutral ceramidase was decreased at both IRI 2d group and at IRI 28d group. In the renal tissues of ischemia-reperfusion AKI mice, both total Cer(d18:1) and Cer(d18:1/16:0) levels were significantly elevated at 6 hours after IRI, but the levels gradually began to decline thereafter, and basically decreased to the level of the sham-operated group at 48 hours after IRI. The expression of renal acid ceramidase increased at IRI 48h group compared to the sham group, while the expression of neutral ceramidase decreased at IRI 48h group. Intervention with acid ceramidase inhibitor ARN14974 and neutral ceramidase inhibitor C6-urea-ceramide did not alleviate nor aggravate AKI. Ceramidase activator adiporon could significantly alleviate renal tubular injury, and improve renal function. Conclusion: Renal ceramidase plays a protective role in AKI, activating ceramidase could promote renal function in AKI. Funding: Government Support – Non-U.S.