title: Possible involvement of sphingomyelin in the regulation of the plasma sphingosine 1-phosphate level in human subjects.
abstract: OBJECTIVE
  Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid mediator. Although the plasma S1P concentration is reportedly determined by cellular components, including erythrocytes, platelets, and vascular endothelial cells, the possible involvement of other factors, such as serum sphingomyelin (SM) and autotaxin (ATX), remains to be elucidated.
  
  
  METHODS
  We measured S1P using high-performance liquid chromatography (HPLC), SM and lysophosphatidic acid (LPA) using enzymatic assays, ATX antigen using a two-site enzyme immunoassay, and ATX activity using a lysophospholipase D activity assay. To fractionate the lipoproteins, plasma samples were separated using fast protein liquid chromatography (FPLC) utilizing a Superose 6 column.
  
  
  RESULTS
  The plasma S1P level was positively correlated with the levels of SM and lysophosphatidylcholine, but not with the level of phosphatidylcholine. Although SM was present in the very low-density lipoprotein (VLDL) fraction, neither the plasma S1P level nor the SM level was affected by feeding. The plasma S1P level was negatively correlated with the ATX activity. Although the incubation of 100 μmol/L of sphingosylphosphorylcholine (SPC) with the serum resulted in a significant increase in the S1P level because of the presence of ATX, the physiological concentration of SPC did not mimic this effect.
  
  
  CONCLUSIONS
  The plasma S1P level was affected by the serum SM level, while the possibility of ATX involvement in the increase in the plasma S1P level was considered to be remote at least in healthy human subjects.
authors: Analytical Laboratory Chemistry, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan.
authors: Ryunosuke
authors: R
authors: Ohkawa
authors: Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors: Makoto
authors: M
authors: Kurano
authors: Department of Transfusion Medicine, The University of Tokyo Hospital, Tokyo, Japan.
authors: Yuko
authors: Y
authors: Mishima
authors: Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan.
authors: Takahiro
authors: T
authors: Nojiri
authors: Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan; Laboratory of Pathology, Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Kagawa, Japan.
authors: Yasunori
authors: Y
authors: Tokuhara
authors: Diagnostics R&D Division, Alfresa Pharma Corporation, Osaka, Japan.
authors: Tatsuya
authors: T
authors: Kishimoto
authors: Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan.
authors: Kazuhiro
authors: K
authors: Nakamura
authors: Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan.
authors: Shigeo
authors: S
authors: Okubo
authors: Department of Medical Technology, School of Health Sciences, Tokyo University of Technology, Tokyo, Japan.
authors: Shigemi
authors: S
authors: Hosogaya
authors: Department of Clinical and Laboratory Medicine, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.
authors: Yukio
authors: Y
authors: Ozaki
authors: Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan; Clinical Laboratory Program Education Development Center Faculty of Science, Toho University, Chiba, Japan.
authors: Hiromitsu
authors: H
authors: Yokota
authors: Bioscience Division, Reagent Development Department, AIA Research Group, TOSOH Corporation, Kanagawa, Japan.
authors: Koji
authors: K
authors: Igarashi
authors: Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan; Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors: Hitoshi
authors: H
authors: Ikeda
authors: Analytical Laboratory Chemistry, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Minoru
authors: M
authors: Tozuka
authors: Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan; Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan. Electronic address: yatoyuta-tky@umin.ac.jp.
authors: Yutaka
authors: Y
authors: Yatomi
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D008246:Lysophospholipids / Q000097:blood*; D008297:Male; D010727:Phosphoric Diester Hydrolases / Q000097:blood*; D013109:Sphingomyelins / Q000097:blood*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000097:blood; D000099189:Lysophospholipase D
chemical_list: D015415:Biomarkers; D008246:Lysophospholipids; D010727:Phosphoric Diester Hydrolases; D013109:Sphingomyelins; D013110:Sphingosine; D000099189:Lysophospholipase D; C060506:sphingosine 1-phosphate
keywords: Autotaxin; Sphingomyelin; Sphingosine 1-phosphate