Abstract 226: Myeloid Deletion Of Rage Induces Insulin Resistance By Impairing Macrophage And Adipocyte Crosstalk In Obese Adipose Tissues

Abstract

Introduction: Obesity, a major global health problem, is often associated with insulin resistance (IR). We previously showed that global or adipose tissue-specific Ager deletion protected from high fat diet (HFD) induced obesity and IR. We reported that upon HFD feeding, myeloid-specific deletion of Ager deleted (MDR) significantly impairs insulin sensitivity without differences in body mass vs. myeloid- Ager expressing controls. These adverse effects of myeloid- Ager deletion (body mass, IR) were rescued by simultaneous deletion of adipocyte Ager. The expression of inflammatory genes was significantly higher in the epididymal adipose tissue (eWAT) of MDR vs. controls. Here, we probed for the crosstalk mechanisms between macrophages and adipocytes in obese eWAT using Single nuclei RNA-sequencing technology. Methods: We generated mice with myeloid-specific (MDR) LyzMCre(+/+).Ager flox/flox and adipocyte and myeloid-specific (Double Knockouts (KO)) AdipoQCre(-/+)LyzMCre(+/+).Ager flox/flox deletion of Ager ; LysMCre mice (Cre control) were controls. Mice were fed HFD (60% kcal/fat) for 3 months and assessed for body mass and glucose and insulin tolerance. After 12 weeks, eWAT were isolated and nuclei sequenced using 10x Genomics’ Single Nuclei RNA-sequencing technology and subjected to analyses. Results: Analysis of the snRNA-sequencing data showed a potential crosstalk between macrophages and adipocytes, which was impaired in the eWAT of HFD fed MDR mice. The significantly differentially regulated pathways between the groups identified in adipocytes and macrophages include: Autophagy, Lipid metabolism, Oxidative phosphorylation and Glycolysis. In vivo, the eWAT of MDR mice on HFD exhibited: larger adipocyte size with impaired autophagy of lipid filled adipocytes and fewer crown like structures vs. controls. In vitro, oxidative phosphorylation and lipid metabolism were impaired in the MDR macrophages vs control upon palmitate/oleate treatment, a mimic of HFD. Conclusion: These experiments reveal for the first time protective roles for RAGE in macrophages in HFD feeding; unveiling a novel role for RAGE in adipocyte/macrophage intrinsic and cross-talk communications in obesity and IR.