Subcutaneous adipose tissue fatty acid desaturation in adults with and without rare adipose disorders.
BACKGROUND
Elevated stearoyl-CoA desaturase activity has been described in obese states, with an increased desaturation index (DI) suggesting enhanced lipogenesis. Differences in the DI among various phenotypes of abnormal adiposity have not been studied. Abnormal accumulation of subcutaneous adipose tissue occurs in rare adipose disorders (RADs) including Dercum's disease (DD), multiple symmetric lipomatosis (MSL), and familial multiple lipomatosis (FML). Examining the DI in subcutaneous fat of people with DD, MSL and FML may provide information on adipose tissue fatty acid metabolism in these disorders. The aims of this pilot study were: 1) to determine if differences in adipose tissue DIs are present among RADs, and 2) to determine if the DIs correlate to clinical or biochemical parameters.


METHODS
Subcutaneous adipose tissue was obtained from human participants with DD (n = 6), MSL (n = 5), FML (n = 8) and obese Controls (n = 6). Fatty acid composition was determined by gas chromatography/mass spectrometry. The DIs (palmitoleic/palmitic, oleic/stearic, vaccenic/stearic ratios) were calculated from the gas chromatogram peak intensities. SCD1 gene expression was determined. Spearman's correlations between the DIs and available clinical or biochemical data were performed.


RESULTS
In DD subjects, the vaccenic/stearic index was lower (p < 0.05) in comparison to Controls. Percent of total of the saturated fatty acid myristic acid was higher in DD compared with Controls and FML. Percent of monounsaturated vaccenic acid in DD trended lower when compared with Controls, and was decreased in comparison to FML. In MSL, total percent of the polyunsaturated fatty acids was significantly lower than in the Control group (p < 0.05). In the total cohort of subjects, the palmitoleic/palmitic and oleic/stearic DIs positively correlated with age, BMI, and percent body fat.


CONCLUSIONS
The positive associations between the DIs and measures of adiposity (BMI and percent body fat) support increased desaturase activity in obesity. The lower vaccenic/stearic DI in DD SAT compared with Controls suggests presence of other factors involved in fat accumulation in addition to lifestyle. Other mechanisms driving fat accumulation in DD such as inflammation or lymphatic dysfunction should be investigated.
Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Department of Pediatrics, Division of Endocrinology, 1000 West Carson Street, Harbor Box 446, Torrance, CA 90509, USA. jyee@labiomed.org
Jennifer K
JK
Yee
Susan A
SA
Phillips
Kambiz
K
Allamehzadeh
Karen L
KL
Herbst
D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D005227:Fatty Acids / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006801:Humans; D050155:Lipogenesis; D008068:Lipomatosis / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism; D013230:Stearoyl-CoA Desaturase / Q000235:genetics / Q000378:metabolism; D050151:Subcutaneous Fat / Q000378:metabolism*
D005227:Fatty Acids; C523776:SCD1 protein, human; D013230:Stearoyl-CoA Desaturase