ABSTRACT
Adipose tissue macrophages (ATMs) infiltrate adipose tissue during obesity and contribute to insulin resistance. We hypothesized that macrophages migrating to adipose tissue upon high-fat feeding may differ from those that reside there under normal diet conditions. To this end, we found a novel F4/80(+)CD11c(+) population of ATMs in adipose tissue of obese mice that was not seen in lean mice. ATMs from lean mice expressed many genes characteristic of M2 or "alternatively activated" macrophages, including Ym1, arginase 1, and Il10. Diet-induced obesity decreased expression of these genes in ATMs while increasing expression of genes such as those encoding TNF-alpha and iNOS that are characteristic of M1 or "classically activated" macrophages. Interestingly, ATMs from obese C-C motif chemokine receptor 2-KO (Ccr2-KO) mice express M2 markers at levels similar to those from lean mice. The antiinflammatory cytokine IL-10, which was overexpressed in ATMs from lean mice, protected adipocytes from TNF-alpha-induced insulin resistance. Thus, diet-induced obesity leads to a shift in the activation state of ATMs from an M2-polarized state in lean animals that may protect adipocytes from inflammation to an M1 proinflammatory state that contributes to insulin resistance.
Subject(s)
Adipose Tissue/pathology , Adipose Tissue/physiopathology , Macrophages/physiology , Obesity/physiopathology , 3T3 Cells , Animals , Base Sequence , Biological Transport , DNA Primers , Deoxyglucose/metabolism , Dietary Fats , Disease Models, Animal , Energy Intake , Male , Mice , Mice, Inbred C57BL , Mice, Obese , Obesity/genetics , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
Although recent studies show that adipose tissue macrophages (ATMs) participate in the inflammatory changes in obesity and contribute to insulin resistance, the properties of these cells are not well understood. We hypothesized that ATMs recruited to adipose tissue during a high-fat diet have unique inflammatory properties compared with resident tissue ATMs. Using a dye (PKH26) to pulse label ATMs in vivo, we purified macrophages recruited to white adipose tissue during a high-fat diet. Comparison of gene expression in recruited and resident ATMs using real-time RT-PCR and cDNA microarrays showed that recruited ATMs overexpress genes important in macrophage migration and phagocytosis, including interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), and C-C chemokine receptor 2 (CCR2). Many of these genes were not induced in ATMs from high-fat diet-fed CCR2 knockout mice, supporting the importance of CCR2 in regulating recruitment of inflammatory ATMs during obesity. Additionally, expression of Apoe was decreased, whereas genes important in lipid metabolism, such as Pparg, Adfp, Srepf1, and Apob48r, were increased in the recruited macrophages. In agreement with this, ATMs from obese mice had increased lipid content compared with those from lean mice. These studies demonstrate that recruited ATMs in obese animals represent a subclass of macrophages with unique properties.
Subject(s)
Adipose Tissue/physiopathology , Diet , Dietary Fats , Inflammation/physiopathology , Macrophages/physiology , Obesity/physiopathology , Adipose Tissue/pathology , Animals , Fluorescent Dyes , Inflammation/pathology , Macrophages/pathology , Male , Mice , Mice, Inbred C57BL , Organic ChemicalsABSTRACT
In 2001, the Centers for Disease Control and Prevention funded three Centers for Genomics and Public Health to develop training tools for increasing genomic awareness. Over the past three years, the centers, working together with the Centers for Disease Control and Prevention's Office of Genomics and Disease Prevention, have developed tools to increase awareness of the impact genomics will have on public health practice, to provide a foundation for understanding basic genomic advances, and to translate the relevance of that information to public health practitioners' own work. These training tools serve to communicate genomic advances and their potential for integration into public heath practice. This paper highlights two of these training tools: 1) Genomics for Public Health Practitioners: The Practical Application of Genomics in Public Health Practice, a Web-based introduction to genomics, and 2) Six Weeks to Genomic Awareness, an in-depth training module on public health genomics. This paper focuses on the processes and collaborative efforts by which these live presentations were developed and delivered as Web-based training sessions.