Blood sphingolipidomics in healthy humans: impact of sample collection methodology.
We used a HPLC-MS/MS methodology for determination of a basic metabolomic profile (18:1,18:0 sphingoid backbone, C(14)-C(26) N-acyl part) of "normal" sphingolipid levels in human serum and plasma. Blood was collected from healthy males and nonpregnant females under fasting and nonfasting conditions with and without anticoagulants. Sphingolipids analyzed included sphingoid bases, sphingosine and dihydrosphingosine, their 1-phosphates (S1P and dhS1P), molecular species (C(n)-) of ceramide (Cer), sphingomyelin (SM), hexosylceramide (HexCer), lactosylceramide (LacCer), and Cer 1-phosphate (Cer1P). SM, LacCer, HexCer, Cer, and Cer1P constituted 87.7, 5.8, 3.4, 2.8, and 0.15% of total sphingolipids, respectively. The abundant circulating SM was C(16)-SM (64.0 µM), and it increased with fasting (100 µM). The abundant LacCer was C(16)-LacCer (10.0 µM) and the abundant HexCer was C(24)-HexCer (2.5 µM). The abundant Cer, C(24)-Cer (4.0 µM), was not influenced by fasting; however, levels of C(16)-C(20) Cers were decreased in response to fasting. S1P levels were higher in serum than plasma (0.68 µM vs. 0.32 µM). We also determined levels of sphingoid bases and SM species in isolated lipoprotein classes. HDL(3) was the major carrier of S1P, dhS1P, and Sph, and LDL was the major carrier of Cer and dhSph. Per particle, VLDL contained the highest levels of SM, Cer, and S1P. HPLC-MS/MS should provide a tool for clinical testing of circulating bioactive sphingolipids in human blood.
Hammad
Samar M
SM
Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, USA. hammadsm@musc.edu
Pierce
Jason S
JS
Soodavar
Farzan
F
Smith
Kent J
KJ
Al Gadban
Mohammed M
MM
Rembiesa
Barbara
B
Klein
Richard L
RL
Hannun
Yusuf A
YA
Bielawski
Jacek
J
Bielawska
Alicja
A
D000328:Adult; D002518:Ceramides / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005260:Female; D006493:Heparin / Q000097:blood; D006801:Humans; D008297:Male; D040901:Proteomics / Q000379:methods; D013107:Sphingolipids / Q000097:blood*; D013109:Sphingomyelins / Q000097:blood; D013110:Sphingosine / Q000097:blood; D053719:Tandem Mass Spectrometry / Q000379:methods*
D002518:Ceramides; D013107:Sphingolipids; D013109:Sphingomyelins; D006493:Heparin; D013110:Sphingosine