on January 31, 2008
Published online before print January 31, 2008, doi: 10.1161/ATVBAHA.107.157685
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Submitted on October 10, 2007
Accepted on January 22, 2008
Dietary Cholesterol Worsens Adipose Tissue Macrophage Accumulation and Atherosclerosis in Obese LDL Receptor–Deficient Mice
Savitha Subramanian ;
From the Departments of Medicine (S.S., C.Y.H., T.C., T.S.M., S.A.W., A.H., K.D.O., A.C.), and Pathobiology (E.A.K.), University of Washington, Seattle.
* To whom correspondence should be addressed. E-mail: achait{at}u.washington.edu.
Objective—Chronic systemic inflammation accompanies obesity and predicts development of cardiovascular disease. Dietary cholesterol has been shown to increase inflammation and atherosclerosis in LDL receptor–deficient (LDLR-/-) mice. This study was undertaken to determine whether dietary cholesterol and obesity have additive effects on inflammation and atherosclerosis.
Methods and Results—LDLR-/- mice were fed chow, high-fat, high-carbohydrate (diabetogenic) diet without (DD) or with added cholesterol (DDC) for 24 weeks. Effects on adipose tissue, inflammatory markers, and atherosclerosis were studied. Despite similar weight gain between DD and DDC groups, addition of dietary cholesterol increased insulin resistance relative to DD. Adipocyte hypertrophy, macrophage accumulation, and local inflammation were observed in intraabdominal adipose tissue in DD and DDC, but were significantly higher in the DDC group. Circulating levels of the inflammatory protein serum amyloid A (SAA) were 4.4-fold higher in DD animals and 15-fold higher in DDC animals than controls, suggesting chronic systemic inflammation. Hepatic SAA mRNA levels were similarly elevated. Atherosclerosis was increased in the DD-fed animals and further increased in the DDC group.
Conclusions—Obesity-induced macrophage accumulation in adipose tissue is exacerbated by dietary cholesterol. These local inflammatory changes in adipose tissue are associated with insulin resistance, systemic inflammation, and increased atherosclerosis in this mouse model.
Key words: atherosclerosis • inflammation • obesity • lipoproteins • diet