Abstract
Endothelial dysfunction contributes to sepsis outcome. Metabolic phenotypes associated with endothelial dysfunction are not well characterised in part due to difficulties in assessing endothelial metabolism in situ. Here, we describe the construction of iEC2812, a genome scale metabolic reconstruction of endothelial cells and its application to describe metabolic changes that occur following endothelial dysfunction. Metabolic gene expression analysis of three endothelial subtypes using iEC2812 suggested their similar metabolism in culture. To mimic endothelial dysfunction, an in vitro sepsis endothelial cell culture model was established and the metabotypes associated with increased endothelial permeability and glycocalyx loss after inflammatory stimuli were quantitatively defined through metabolomics. These data and transcriptomic data were then used to parametrize iEC2812 and investigate the metabotypes of endothelial dysfunction. Glycan production and increased fatty acid metabolism accompany increased glycocalyx shedding and endothelial permeability after inflammatory stimulation. iEC2812 was then used to analyse sepsis patient plasma metabolome profiles and predict changes to endothelial derived biomarkers. These analyses revealed increased changes in glycan metabolism in sepsis non-survivors corresponding to metabolism of endothelial dysfunction in culture. The results show concordance between endothelial health and sepsis survival in particular between endothelial cell metabolism and the plasma metabolome in patients with sepsis.
Highlights
Sepsis is a life-threatening systemic inflammatory condition caused by the body’s response to infection, leading to fever, increased heart and breathing rates and septic shock is the subset of these patients with hypotension and altered serum lactate[1,2,3]
Endothelial permeability is dependent on fatty acid oxidation[22] and arachidonic acid, ceramide, tryptophan, and arginine metabolism have all been shown to be important in sepsis progression[23,24,25,26,27,28]
We focused our study on metabolic changes in cultured human umbilical vein endothelial cells (HUVECs) stimulated with combinations of LPS and Interferon γ (IFNγ) to parametrize the model to endothelial dysfunction
Summary
Sepsis is a life-threatening systemic inflammatory condition caused by the body’s response to infection, leading to fever, increased heart and breathing rates and septic shock is the subset of these patients with hypotension and altered serum lactate[1,2,3]. The full functional relevance of endothelial metabolic changes in sepsis are not fully understood This knowledge gap is partly due to the difficulty of sampling directly from the endothelium in vivo and of separating endothelial metabolism from that of other cell types[29]. A proteomics based GEM has recently been built for the endothelium and identified a role for carnitine palmitoyl transferase in endothelial permeability[22]. These developments present an intriguing possibility for the treatment of sepsis, given the variable patient response to treatment[11,29]. We demonstrate that iEC2812 bridges a gap between in vitro and clinical research and represents a platform for the future systems analysis of endothelial metabolism
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