Obesity Spurs Macrophage Infiltration of Adipose Tissue

Diet-induced obesity, but not hyperlipidemia, promotes accumulation in white adipose tissue

FRIDAY, March 16 (HealthDay News) -- Diet-induced obesity causes macrophages to infiltrate white adipose tissue, but hyperlipidemia does not, according to a study of mice published in the March issue of Diabetes.

Alyssa H. Hasty, Ph.D., of the Vanderbilt University Medical Center in Nashville, Tenn., and colleagues placed obesity-prone, low-density lipoprotein receptor-deficient agouti yellow mice on chow or Western diet with a fat source consisting of 69 percent saturated fat, 27 percent monounsaturated fat and 4 percent polyunsaturated fat. They also placed another group of low-density lipoprotein receptor-sufficient mice on a Western diet.

The researchers found that only the mice fed a Western diet had elevated levels of plasma lipids. Although they found that macrophage accumulation in white adipose tissue increased in tandem with the degree of adiposity, they determined that hyperlipidemia had no effect on macrophage recruitment.

"Collectively, our data suggest that hyperlipidemia does not contribute to obesity-driven adipose tissue resident macrophages accumulation and its downstream pathophysiological consequences such as inflammation and insulin resistance," the authors conclude. "These data may have important implications to the pathogenesis of diet-induced obesity, even when plasma lipid abnormalities are not present."

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