RNA silencing machinery in extracellular vesicle-mediated immunometabolic regulation - Project Summary Obesity has solid inflammatory underpinnings, which are risk factors for various chronic inflammatory and metabolic diseases such as type 2 diabetes (T2D). However, how obesity provokes aberrant inflammation remains to be defined. Recent studies indicate that small extracellular vesicles (sEVs, a.k.a., exosomes) carrying RNA, including microRNA (miRNA), play a critical role in inducing inflammation in obesity. In this study, we aim to demonstrate that RNA silencing machinery plays a critical role in modulating RNA cargo profiles in sEV-secreting cells and also in responding to exposure of RNA cargos of sEVs in sEV-receiving cells. Our overarching goal is to reveal how RNA silencing machinery-mediated, sEV-induced events are critical for controlling obesity-associated inflammation, impacting the development of chronic inflammatory and metabolic diseases. Small EVs are released from many cell types into the extracellular space and are distributed in body fluids. These sEVs, taken up by neighboring and distant cells, subsequently modulate the functions of recipient cells. Hence sEVs have emerged as important transducers of intercellular communication, with their cargos, including miRNAs, playing critical roles in modulating sEV-recipient cellular activities. Our Preliminary data show that circulating EVs from obese adolescents are enriched with specific RNA cargo and exhibit higher pro-inflammatory traits, than those from lean subjects. Further, our newly established mouse model, which enables us to monitor specific cell type-derived sEVs in vivo, indicates that in obesity, sEVs become pro- inflammatory and when engulfed by macrophages, these pro-inflammatory sEVs induce inflammatory responses in macrophages. These intriguing Preliminary data suggest novel mechanisms for EV-induced inflammation in obesity. Studies in this proposal will: (1) assess the role of RNA silencing machinery in sEV-secreting cells in generating pro-inflammatory sEVs, and (2) evaluate the role of RNA silencing machinery in sEV-receiving cells in mediating sEV-induced inflammation. By utilizing our novel mouse models coupled with access to human samples and models, our systematic approaches will reveal novel mechanisms of how the pathogenicity of sEVs is critical in the development of inflammation in obesity-associated pathophysiology.
