Tohoku J. Exp. Med., 2012, 227(1)

Attenuation of Kidney Injuries Maintains Serum Sulfatide Levels Dependent on Hepatic Synthetic Ability: A Possible Involvement of Oxidative Stress

XIAONA SHENG,^1,2 TAKERO NAKAJIMA,¹ LIXUAN WANG,^1,3 XIAOWEI ZHANG,^1,4 YUJI KAMIJO,^1,5 KYOKO TAKAHASHI,^1,5 NAOKI TANAKA,¹ EIKO SUGIYAMA,^1,6 MAMORU KYOGASHIMA,⁷ TOSHIFUMI AOYAMA¹ and ATSUSHI HARA¹

¹Department of Metabolic Regulation, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, Matsumoto, Japan
²Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, P.R. China
³Department of Histology and Embryology, Hebei Medical University, Shijiazhuang, P.R. China
⁴Department of Neurosurgery, The Second Hospital of Hebei Medical University, Shijiazhuang, P.R. China
⁵Department of Nephrology, Shinshu University School of Medicine, Matsumoto, Japan
⁶Department of Nutritional Science, Nagano Prefectural College, Nagano, Japan
⁷Division of Microbiology and Molecular Cell Biology, Nihon Pharmaceutical University, Saitama, Japan

Serum sulfatides are the major glycosphingolipids in lipoproteins. Although serum sulfatides are mainly synthesized and secreted by the liver, they are significantly decreased when the kidneys are impaired. Our recent experimental study using a murine protein-overload nephropathy model suggested a hypothetical mechanism whereby serum sulfatides were reduced due to kidney dysfunction. This was the result of decreased hepatic expression of a sulfatide synthetic enzyme, cerebroside sulfotransferase (CST), which is associated with systemic enhancement of oxidative stress. However, there is a possibility that the experimental process, protein-overload itself, directly affected the sulfatide metabolism and oxidative stress in the liver. To determine whether kidney dysfunction actually reduces the hepatic synthesis of sulfatides via oxidative stress, we examined sulfatide levels, the hepatic content of metabolic sulfatide enzymes, and the degree of oxidative stress in protein-overload mice subjected to renoprotective therapy using clofibrate, a representative hypolipidemic medicine. Protein-overload mice exhibited marked kidney injuries, enhancement of hepatic oxidative stress, decreased levels of serum and hepatic sulfatides, and decreased expression of hepatic CST. The clofibrate treatment attenuated kidney damage and hepatic oxidative stress while maintaining serum/hepatic sulfatide levels and hepatic CST content in the mice. Because clofibrate monotherapy without protein-overload treatment only minimally affected these hepatic parameters, the hepatic synthesis of sulfatides appeared to be strongly influenced by kidney dysfunction and subsequent oxidative stress. This study suggests that the crosstalk between kidney dysfunction and hepatic sulfatide metabolism is mediated by oxidative stress. These results should help to understand the phenomenon in patients with end-stage kidney disease.

keywords —— cerebroside sulfotransferase; clofibrate; kidney injury; oxidative stress; sulfatides

© 2012 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2012, 227, 1-12

Correspondence: Takero Nakajima, Ph.D. and Yuji Kamijo, M.D., Ph.D., Department of Metabolic Regulation, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.

e-mail: nakat@shinshu-u.ac.jp; yujibeat@shinshu-u.ac.jp