SVF mediates immunometabolic alterations in burn-induced hypermetabolic adipose tissue via mitochondrial transfer

Adipose tissue (AT) browning promotes systemic alterations in energy expenditure as a response to catecholamine-induced hypermetabolism in severe burn trauma. The AT is composed of the stromal vascular fraction (SVF) and adipocytes. SVF contains a vast population of immune cells that maintain AT homeostasis. Despite evidence that local immune cell accumulation contributes to hypermetabolism, the underlying mechanism of persistent browning response is not known. Thus, we hypothesized that a specific cellular communication between adipocytes and SVF can mediate the severe metabolic alterations associated with hypermetabolism. Therefore, we used a murine burn model to show that postburn hypermetabolism compromises mitochondria respiration and alters the immune cell profile of the AT-SVF. We found that adipocyte-derived signals promote metabolic reprogramming and inflammatory responses by SVF after burns in both mice and humans. Interestingly, adipocytes transfer mitochondria to cells in the SVF including different immune cell (macrophages, T cells, B cells) uptake mitochondria from adipocytes. Such data were replicated in human samples as well. These results indicate that adipocytes play a major role in immunometabolic reprogramming following severe burns through crosstalk with the adipose immune cell population. Therefore, targeting immune cell metabolism restoration is a potential strategy to mitigate the detrimental effects of postburn hypermetabolism on systemic energy balance.