Submitted on June 15, 2007
Accepted on January 3, 2008
The role of macrophage leptin receptor in aortic root lesion formation
Bonnie Kae Surmi1, Robin D Atkinson1, Marnie Lorn Gruen1, Kimberly Ray Coenen1, and Alyssa H Hasty1*
1 Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee, United States
* To whom correspondence should be addressed. E-mail: alyssa.hasty{at}vanderbilt.edu.
Plasma leptin is often elevated in obese individuals, and previous studies have suggested leptin as a factor that links obesity and atherosclerosis. Because macrophages play a key role in atherogenesis and are responsive to leptin, we hypothesized that leptin increases aortic root lesion formation, in part, through macrophage leptin receptor (LepR). Three different bone marrow transplantation studies were conducted in which bone marrow, with or without LepR, was transplanted into lethally irradiated: 1) LDL receptor deficient (LDLR-/-) mice with moderate hyperleptinemia due to Western diet (WD) feeding, 2) LDLR-/- mice with WD feeding plus pharmacologically induced hyperleptinemia (daily injection of 125 µg leptin), or 3) obese, hyperleptinemic, LepR deficient LDLR-/- (LepRdb/db;LDLR-/-) mice. Minor differences in plasma parameters such as cholesterol, triglycerides, and insulin were observed in some groups; however, a consistent trend for the role of LepR on these parameters was not detected. In each of the studies, macrophage LepR expression did not have an effect on aortic root atherosclerotic lesion formation. These results suggest that non-hematopoietic cells may have a more significant role than macrophages in leptin-mediated effects on aortic root lesion formation.
