TY - JOUR
T1 - Palmitoleic acid is elevated in fatty liver disease and reflects hepatic lipogenesis
AU - Lee, Joseph J.
AU - Lambert, Jennifer E.
AU - Hovhannisyan, Yelena
AU - Ramos-Roman, Maria A.
AU - Trombold, Justin R.
AU - Wagner, David A.
AU - Parks, Elizabeth J.
N1 - Publisher Copyright:
© 2015 American Society for Nutrition
PY - 2015/1/1
Y1 - 2015/1/1
N2 - 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% oxf 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 VLDLtriacylglycerols corresponded to a stronger signal of elevated DNL. Conclusion: The current data provide support for the use of the VLDLtriacylglycerol 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. This trial was registered at clinicaltrials.gov as NCT01371396.
AB - 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% oxf 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 VLDLtriacylglycerols corresponded to a stronger signal of elevated DNL. Conclusion: The current data provide support for the use of the VLDLtriacylglycerol 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. This trial was registered at clinicaltrials.gov as NCT01371396.
KW - Biomarker
KW - Lipogenesis
KW - Palmitoleic fatty acid
KW - Stearoyl-CoA desaturase
KW - VLDL triacylglycerol
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U2 - 10.3945/ajcn.114.092262
DO - 10.3945/ajcn.114.092262
M3 - Article
C2 - 25527748
AN - SCOPUS:84919626918
SN - 0002-9165
VL - 101
SP - 34
EP - 43
JO - American Journal of Clinical Nutrition
JF - American Journal of Clinical Nutrition
IS - 1
ER -