Abstract Body: Weight loss in obesity reduces the risk of cardiovascular events, with mechanisms largely unknown. A deeper understanding of these processes could pave the way for innovative therapies targeting obesity complications. We were the first to directly show that resolution of atherosclerosis occurs in obese mice upon weight loss. Specifically, caloric restriction (CR) after atherosclerosis establishment in Ldlr-/- mice, through limiting Western Diet intake by 30% for only 2 weeks, resulted in reduction of plaque inflammation and necrotic core content. Using single-cell RNA-sequencing we found that CR-induced atherosclerosis resolution was correlated with an accumulation of a unique macrophage (Mø) subtype in visceral adipose tissue, termed CR-Møs, which can be distinguished by high expression of the gene Fcgr4.
Building on these findings, here we hypothesized that CR-Møs could serve as a therapy for atherosclerosis. Given the scarcity of CR-Møs in vivo, we developed an in vitro system to induce CR-Mø differentiation from primary Møs using media conditioned by CR adipose. This approach resulted in a significant increase in Fcgr4 expression in naive Møs. Moreover, the in vitro-generated CR-Møs exhibited significantly enhanced efferocytosis, the process of clearing apoptotic cells, which is typically impaired in atherosclerosis and contributes to necrotic core formation and expansion. Interestingly, overexpression of Fcgr4 rendered naive Møs high efferocytotic ability, indicating the Fcgr4 is responsible for the increased efferocytosis of CR-Møs. These observations suggest that CR-Mø treatment could mitigate plaque necrotic cores. To assess the therapeutic potential of CR-Møs, Ldlr-/- mice with established atherosclerosis were randomized into groups (n=8) and received intravenous injections of either control-Møs or CR-Møs every four days for four weeks. Subsequent tissue analysis revealed that treatment with CR-Møs led to reduced plaque complexity and necrotic core size, suggesting CR-Møs are an effective treatment for atherosclerosis.
In conclusion, we are the first to demonstrate that weight loss promotes atherosclerosis resolution via specialized pro-resolving Mø accumulation. CR-Møs, with their superior efferocytotic function enabled by elevated Fcgr4 expression, have shown the potential to ameliorate atherosclerosis in a pre-clinical model. These findings highlight the exciting potential of CR-Møs as novel therapeutics for atherosclerosis treatment.