An adipocyte-endothelial framework to identify molecular signatures of metabolic vulnerability in obesity

Obesity-related metabolic disease is linked to impaired adipose tissue function, but the underlying molecular programs are difficult to assign to specific adipose-resident cell types, to mechanistically connect to inflammation, and to distinguish from alterations that normalize with weight loss. We integrated here a layered design combining untargeted proteomics and lipidomics to define obesity-associated, cell-type-resolved molecular phenotypes across isolated adipocytes and adipose microvascular endothelial cells, explore whether an obesity-like inflammatory milieu reproduces adipose-resident cell dysfunction, and identify molecular features that show evidence of recovery after surgery-induced weight loss. As expected, adipocytes from people with obesity show suppression of mitochondrial energy metabolism together with impaired lipid plasticity, as reflected by triglyceride remodelling. By mimicking an obesity-like inflammatory milieu with macrophage-conditioned media, we reproduced most of these changes in adipocyte cultures. Endothelial cells exhibited yet another, opposite trajectory in obesity, with reduced cell-cycle signalling and increased mitochondrial activation, which were recapitulated in vitro when these cells were exposed, respectively, to the secretions of inflamed macrophages and adipocytes. Bulk adipose tissue proteomes and lipidomes showed evidence of metabolic improvement after weight loss, with broad restoration of mitochondrial and substrate-handling pathways and reciprocal triglyceride remodelling. Alongside the inflammation-responsive adipocyte mitochondrial and lipid-handling dysfunction, our cell-type-informed framework probes macrophage and adipocyte-to-endothelial activation in obesity and delineates cross-context cellular programs that recover with weight loss. Additionally, we identified the elements that exhibit the strongest association with dyslipidaemia, hypertriglyceridemia and hyperglycaemia in individuals with obesity, confirming molecular signatures relevant to metabolic obesity in two cross-sectional samples.