Related Experiment Video
Updated: Aug 14, 2026
Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages
Published on: June 23, 2013
Leptin down-regulates peroxisome proliferator-activated receptor gamma (PPAR-gamma) mRNA levels in primary human
Agatha Cabrero1, Marta Cubero, Gemma Llaverías
1Unitat de Farmacologia, Departament de Farmacologia i Química Terapèutica, Facultat de Farmàcia, University of Barcelona, Spain.
Abstract:
Increased leptin levels are associated with cardiovascular disease in obesity although the mechanism is unknown. Peroxisome proliferator-activated receptor gamma (PPARgamma) is a key regulator of macrophage lipid metabolism and its activation by thiazolidinediones protects against atherosclerosis. The aim of this study was to assess the effects of human recombinant leptin on PPARgamma mRNA levels in primary human macrophages and macrophage-derived foam cells. Leptin treatment (100 ng/ml) for 24 h caused a 41% reduction (p < 0.01) in PPARgamma transcript levels in human-derived macrophages. This fall was accompanied by a reduction in the mRNA expression of carnitine palmitoyltransferase (CPT-I) (36%, p < 0.05) and ABCA1 (62%, p < 0.05), whereas CD36 mRNA reduction (34%) was not significant. In macrophage-derived foam cells, leptin at 20 ng/ml reduced PPARgamma mRNA levels by 33% (p < 0.01) and CPT-I by 27% (p < 0.05). At this concentration, leptin did not modify the expression of either ABCA1 or CD36. In agreement with these results, intracellular cholesterol ester accumulation was not altered in macrophage-derived foam cells by leptin at 20 ng/ml. We propose that the reduction in PPARgamma expression in both macrophages and foam cells may be one of the factors linking high leptin levels and cardiovascular disease.
Insights
High leptin levels may contribute to cardiovascular disease by reducing peroxisome proliferator-activated receptor gamma (PPARgamma) mRNA in macrophages. This reduction impacts lipid metabolism, potentially explaining the link between obesity and heart disease.
Area of Science:
- Biochemistry
- Cell Biology
- Cardiovascular Research
Background:
- Elevated leptin levels in obesity are linked to cardiovascular disease, but the underlying mechanisms remain unclear.
- Peroxisome proliferator-activated receptor gamma (PPARgamma) is crucial for macrophage lipid metabolism and its activation confers protection against atherosclerosis.
Purpose of the Study:
- To investigate the impact of human recombinant leptin on PPARgamma messenger RNA (mRNA) levels in primary human macrophages and macrophage-derived foam cells.
Main Methods:
- Primary human macrophages and macrophage-derived foam cells were treated with varying concentrations of leptin.
- Quantitative real-time PCR was used to measure mRNA expression levels of PPARgamma, carnitine palmitoyltransferase (CPT-I), ABCA1, and CD36.
- Intracellular cholesterol ester accumulation was assessed in foam cells.
Main Results:
- Leptin treatment significantly reduced PPARgamma mRNA levels in both primary macrophages (41%) and foam cells (33%).
- Leptin also decreased CPT-I mRNA in primary macrophages (36%) and foam cells (27%).
- While ABCA1 mRNA was reduced in primary macrophages, leptin did not significantly alter CD36 mRNA or intracellular cholesterol ester accumulation in foam cells.
Conclusions:
- The reduction of PPARgamma expression by leptin in macrophages and foam cells may represent a key mechanism linking elevated leptin levels in obesity to cardiovascular disease.
- Leptin's effect on PPARgamma and associated lipid metabolism genes could contribute to the development of atherosclerosis.
