Insulin resistance in African-American and Caucasian women: differences in lipotoxicity, adipokines, and gene expression in adipose tissue and muscle.
OBJECTIVE
We tested whether African-American (AA) women are different from Caucasian women in regard to lipotoxicity, adipokines, and gene expression in adipose tissue and muscle.


METHODS
Insulin sensitivity (S(I)), plasma adipocytokine levels, intramyocellular lipid (IMCL), and the expression of candidate genes in adipose tissue and muscle were measured in AA and Caucasian women.


METHODS
This study was performed in an ambulatory general clinical research center.


METHODS
Subjects were healthy, nondiabetic AA and Caucasian women.


METHODS
There were no interventions.


METHODS
Comparison of S(I), IMCL, plasma adiponectin, and the expression of candidate genes regulating adipogenesis, lipogenesis, and inflammation in adipose tissue and muscle.


RESULTS
AA had lower plasma adiponectin and IMCL when compared with Caucasian women with similar S(I). In sc adipose tissue (SAT), the expression of genes involved in adipogenesis including peroxisomal proliferator-activated receptor-gamma (PPARgamma) and lipin-1beta were also reduced in SAT of AA subjects (19%, P = 0.06, and 25%, P = 0.05, respectively). Similarly, 1-acylglycerol-3-phosphate acyltransferase 2 (AGPAT 2), stearoyl-coenzyme A desaturase-1 (SCD1), and CD36 mRNA expression was significantly reduced in SAT by 19, 54, and 28% respectively (P < 0.01 for all) in AA compared with Caucasian women. Yet the expression of CD68 in SAT was similar in both ethnic groups. Gene expression studies in muscle revealed a 31% reduction in expression of AGPAT 2 and a 72% reduction in SCD1 genes in AA.


CONCLUSIONS
AA women demonstrated lower expression of several PPARgamma-responsive genes in adipose tissue, lower plasma adiponectin, and decreased IMCL levels as compared with Caucasians, which suggests that African-Americans may be protected from lipotoxicity. Together these data suggest significant ethnic differences in the pathophysiology of insulin resistance.
Smith
Latasha M
LM
Central Baptist College, Conway, Arkansas 72034, USA.
Yao-Borengasser
Aiwei
A
Starks
Tasha
T
Tripputi
Mark
M
Kern
Philip A
PA
Rasouli
Neda
N
D050156:Adipogenesis / Q000235:genetics / Q000502:physiology; D054392:Adipokines / Q000097:blood* / Q000378:metabolism; D000273:Adipose Tissue / Q000378:metabolism*; D050154:Adiposity / Q000235:genetics / Q000502:physiology; D000328:Adult; D001741:Black or African American / Q000235:genetics / Q000706:statistics & numerical data; D015331:Cohort Studies; D005260:Female; D015870:Gene Expression; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D007333:Insulin Resistance / Q000208:ethnology* / Q000502:physiology; D050155:Lipogenesis / Q000235:genetics / Q000502:physiology; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D044465:White People / Q000235:genetics / Q000706:statistics & numerical data
D054392:Adipokines