Short-term caloric restriction promotes resolution, while weight regain accelerates atherosclerosis in mice

While weight loss is highly recommended for obesity, promoting inflammation resolution, >80% of those who lose weight will regain it back, resulting in worsening of disease outcomes (including cardiovascular disease), relative to never having lost weight. However, how weight loss and regain directly influence atherosclerotic inflammation was unknown and investigated in this stud. Using short-term caloric restriction (stCR) in obese mice, we found that weight loss promotes atherosclerosis resolution, independently of plasma cholesterol. Mechanistically, we found that this is partly attributed to a unique subset of macrophage, distinguished by high expression of the antibody receptor Fcgr4, that accumulated in epididymal adipose tissue and plaques with stCR and help to clear necrotic cores. Interestingly, our data suggest that eWAT-derived Fcgr4 macrophages contribute to the clearance of plaque necrotic cores. On the other hand, weight regain achieved by ab libitum feeding following the stCR phase resulted in acceleration of atherosclerosis progression and disappearance of Fcgr4 macrophages from both adipose and plaques. Furthermore, weight regain caused inflammatory reprogramming of bone marrow immune progenitors, retaining hyper-inflammatory capabilities for long periods thereafter. Adipose tissue from calorie restricted mice was digested and cell suspensions from were sorted using BD FACS Aria II SORP. CD45+, CD3-, B220-, Ly6G-, SiglecF-, CD11b+ macrophages were then sorted into either Fcgr4 positive or negative populations using antibodies purchased from BioLegend.