Palmitoleic acid is elevated in fatty liver disease and reflects hepatic lipogenesis

卷:101

Lee, Joseph J. ; Lambert, Jennifer E. ; Hovhannisyan, Yelena ; Ramos-Roman, Maria A. ; Trombold, Justin R. ; Wagner, David A. ; Parks, Elizabeth J.

Univ Missouri

关键词: palmitoleic fatty acid;    VLDL triacylglycerol;    biomarker;    lipogenesis;    stearoyl-CoA desaturase;   

DOI  :  10.3945/ajcn.114.092262

学科分类：食品科学和技术

【 摘 要 】

Background: Biochemical evidence has linked the coordinate control of fatty acid (FA) synthesis with the activity of stearoyl-CoA desaturase-1 (SCD1). The ratio of 16:1n-7 to 16:0 [SCD1((16))] in plasma triacylglycerol FA has been used as an index to reflect liver SCD1((16)) activity and has been proposed as a biomarker of FA synthesis, although this use has not been validated by comparison with isotopically measured de novo lipogenesis (DNLMeas). Objective: We investigated plasma lipid 16:1n-7 and FA indexes of elongation and desaturation in relation to lipogenesis. Design: In this cross-sectional investigation of metabolism, 24 overweight adults, who were likely to have elevated DNL, consumed D2O for 10 d and had liver fat (LF) measured by magnetic resonance spectroscopy. Very-low-density lipoprotein (VLDL)-triacylglycerols and plasma free FA [nonesterified fatty acids (NEFAs)] were analyzed by using gas chromatography for the FA composition (molar percentage) and gas chromatography-mass spectrometry and gas chromatography-combustion isotope ratio mass spectrometry for deuterium enrichment. Results: In all subjects, VLDL-triacylglycerol 16:1n-7 was significantly (P < 0.01) related to DNLMeas (r = 0.56), liver fat (r = 0.53), and adipose insulin resistance (r = 0.56); similar positive relations were shown with the SCD1((16)) index, and the pattern in NEFAs echoed that of VLDL-triacylglycerols. Compared with subjects with low LF (3.1 +/- 2.7%; n=11), subjects with high LF (18.4 +/- 3.6%; n=13) exhibited a 45% higher VLDL-triacylglycerol 16:1n-7 molar percentage (P < 0.01), 16% of subjects had lower 18:2n-6 (P = 0.01), and 27% of subjects had higher DNL as assessed by using a published DNL index (ratio of 16:0 to 18:2n-6; P = 0.03), which was isotopically confirmed by DNLMeas (increased 2.5-fold; P < 0.01). Compared with 16:0 in the diet, the low amount of dietary 16:1n-7 in VLDL-triacylglycerols corresponded to a stronger signal of elevated DNL. Conclusion: The current data provide support for the use of the VLDL-triacylglycerol 16:1n-7 molar percentage as a biomarker for elevated liver fat when isotope use is not feasible; however, larger-scale confirmatory studies are needed.