Reduced cholesterol accumulation by leptin deficient (ob/ob) mouse macrophages

Objective: Although presenting many aspects of the metabolic syndrome, leptin deficient (ob/ob) mice do not spontaneously develop atherosclerosis. To examine the role of leptin in foam cell formation we analyzed ob/ob leukocyte inflammation markers and macrophage cholesterol accumulation. Methods: Resident and thioglycollate (TG) elicited peritoneal cells of ob/ob and wildtype mice were studied. Activation markers, scavenger receptors (SR) and cholesterol accumulation were analyzed using flow cytometry and Taqman analysis. Cytokines, haptoglobin, adiponectin and amyloid A levels were analyzed with ELISA. Results: Macrophages of ob/ob mice had reduced expression of MHC class II, CD11b, CD40, SR-A and CD36 and reduced cholesterol accumulation in vitro. Plasma haptoglobin was increased and T-cell IFN gamma was reduced in ob/ob mice. Peritoneal TG instillation induced an unexpectedly weak inflammatory response in ob/ob mice. Conclusions: The ob/ob mice had a reduced inflammatory response and reduced macrophage cholesterol accumulation in vitro. The data suggest decreased foam cell formation and atherosclerosis development in ob/ob mice.