title: The effect of nephropathy on plasma sphingosine 1-phosphate concentrations in patients with type 2 diabetes.
abstract: OBJECTIVE
  Sphingosine 1-phosphate (S1P) is carried in plasma by the HDL particles and albumin. It mediates several protective functions of HDL. Because of its barrier-enhancing effect, it has attracted attention in diseases associated with endothelial dysfunction. We examined the impact of circulating levels of S1P in diabetic nephropathy together with apoprotein M, a S1P-binding protein in HDL. Plasma levels of dimethylarginines were evaluated in this context.
  
  
  METHODS
  Patients with type 2 diabetes mellitus were divided into three groups according to daily albumin excretion: normoalbuminuria, microalbuminuria and macroalbuminuria (n=30 in each). In addition to routine analysis, S1P and apo M in plasma were measured using the enzyme-linked immunosorbent assays. Asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA) and l-arginine were determined by HPLC. Tukey's or Mann-Whitney U-test was used for the statistics.
  
  
  RESULTS
  Plasma S1P levels showed a significant decline in parallel to kidney dysfunction. The highest significance was detected in the macroalbuminuric group. Although a significant increase in plasma SDMA in albuminuric groups was observed, apo M, l-arginine and ADMA levels were similar between the groups.
  
  
  CONCLUSIONS
  Low plasma levels of S1P seemed to be associated with diabetic nephropathy. The main reason for the decreased S1P levels in our patients seems to be severe urinary albumin loss due to nephropathy. Low levels of S1P in patients with nephropathy may adversely affect the endothelial integrity and barrier function, thus causing a vicious circle.
authors.affiliation: Department of Biochemistry, Istanbul Faculty of Medicine, Istanbul University, Capa, 34093 Istanbul, Turkey. Electronic address: seldabekpinar@hotmail.com.
authors.forename: S
authors.initials: S
authors.lastname: Bekpinar
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Capa, 34093 Istanbul, Turkey.
authors.forename: G
authors.initials: G
authors.lastname: Yenidunya
authors.affiliation: Department of Biochemistry, Istanbul Faculty of Medicine, Istanbul University, Capa, 34093 Istanbul, Turkey.
authors.forename: F
authors.initials: F
authors.lastname: Gurdol
authors.affiliation: Department of Biochemistry, Istanbul Faculty of Medicine, Istanbul University, Capa, 34093 Istanbul, Turkey.
authors.forename: Y
authors.initials: Y
authors.lastname: Unlucerci
authors.affiliation: Department of Biochemistry, Istanbul Faculty of Medicine, Istanbul University, Capa, 34093 Istanbul, Turkey.
authors.forename: E
authors.initials: E
authors.lastname: Aycan-Ustyol
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Capa, 34093 Istanbul, Turkey.
authors.forename: N
authors.initials: N
authors.lastname: Dinccag
mesh_terms: D000419:Albuminuria / Q000097:blood* / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D001053:Apolipoproteins / Q000097:blood; D000075243:Apolipoproteins M; D001120:Arginine / Q000031:analogs & derivatives / Q000097:blood; D001692:Biological Transport; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D003928:Diabetic Nephropathies / Q000097:blood* / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D006801:Humans; D054834:Lipocalins / Q000097:blood; D008246:Lysophospholipids / Q000097:blood*; D008297:Male; D008875:Middle Aged; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000097:blood; D014280:Triglycerides / Q000097:blood
chemical_list: C400523:APOM protein, human; D001053:Apolipoproteins; D000075243:Apolipoproteins M; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D054834:Lipocalins; D008246:Lysophospholipids; D014280:Triglycerides; C060506:sphingosine 1-phosphate; C024917:symmetric dimethylarginine; C018524:N,N-dimethylarginine; D001120:Arginine; D013110:Sphingosine
keywords: Albuminuria; Apoprotein M; Asymmetric dimethylarginine; Diabetic nephropathy; Sphingosine 1-phosphate; Symmetric dimethylarginine