Long-term leptin treatment exerts a pro-apoptotic effect on renal tubular cells via prostaglandin E2 augmentation.
Adipokine leptin reportedly acts on the kidney in pathophysiological states. However, the influence of leptin on renal tubular epithelial cells is still unclear. Gentamicin, a widely used antibiotic for the treatment of bacterial infection, can cause nephrotoxicity. This study aims to investigate the influence of long-term leptin treatment on gentamicin-induced apoptosis in rat renal tubular cells (NRK-52E) and mice. We monitored apoptosis and molecular mechanisms using annexin V/ propidium iodide staining and small interfering RNA transfection. In NRK-52E cells, leptin reduced gentamicin-induced apoptosis at 24h, but significantly increased apoptosis at 48 h. Long-term treatment of leptin decreased Bcl-x(L) expression and increased caspase activity in gentamicin-treated NRK-52E cells. Leptin also increased the expression of cyclooxygenase-2 (COX-2) and its product, prostaglandin E(2) (PGE(2)), in a dose-dependent manner. The COX-2 inhibitor, NS398 (N-[2-(Cyclohexyloxy)-4- nitrophenyl]methanesulfonamide), blocked PGE(2) augmentation and the pro-apoptotic effects of leptin. The addition of PGE(2) recovered the pro-apoptotic effect of leptin in NS398-treated NRK-52E cells. In a mouse animal model, a 10 day leptin treatment significantly increased gentamicin-induced apoptotic cells in proximal tubules. NS398 treatment inhibited this in vivo pro-apoptotic effect of leptin. Results reveal that long-term elevation of leptin induces COX-2-mediated PGE(2) augmentation in renal tubular cells, and then increases these cells' susceptibility to gentamicin-induced apoptosis.
Division of Nephrology, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
Yung-Ho
YH
Hsu
Chung-Yi
CY
Cheng
Yen-Cheng
YC
Chen
Tso-Hsiao
TH
Chen
Yuh-Mou
YM
Sue
Wei-Lun
WL
Tsai
Cheng-Hsien
CH
Chen
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000502:physiology*; D002460:Cell Line; D015232:Dinoprostone / Q000096:biosynthesis / Q000378:metabolism*; D004357:Drug Synergism; D005839:Gentamicins / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000378:metabolism*; D020738:Leptin / Q000008:administration & dosage* / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D051381:Rats; D013997:Time Factors
D051017:Apoptosis Regulatory Proteins; D005839:Gentamicins; D020738:Leptin; D015232:Dinoprostone