Endothelial-to-Mesenchymal Transition in Human Adipose Tissue Vasculature Alters the Particulate Secretome and Induces Endothelial Dysfunction

Abstract

Objective: Endothelial cells (EC) in obese adipose tissue (AT) are exposed to a chronic proinflammatory environment that may induce a mesenchymal-like phenotype and altered function. The objective of this study was to establish whether endothelial-to-mesenchymal transition (EndoMT) is present in human AT in obesity and to investigate the effect of such transition on endothelial function and the endothelial particulate secretome represented by extracellular vesicles (EV). Approach and Results: We identified EndoMT in obese human AT depots by immunohistochemical co-localization of CD31 or vWF and α-SMA (alpha-smooth muscle actin). We showed that AT EC exposed in vitro to TGF-β (tumor growth factor-β), TNF-α (tumor necrosis factor-α), and IFN-γ (interferon-γ) undergo EndoMT with progressive loss of endothelial markers. The phenotypic change results in failure to maintain a tight barrier in culture, increased migration, and reduced angiogenesis. EndoMT also reduced mitochondrial oxidative phosphorylation and glycolytic capacity of EC. EVs produced by EC that underwent EndoMT dramatically reduced angiogenic capacity of the recipient naïve ECs without affecting their migration or proliferation. Proteomic analysis of EV produced by EC in the proinflammatory conditions showed presence of several pro-inflammatory and immune proteins along with an enrichment in angiogenic receptors. Conclusions: We demonstrated the presence of EndoMT in human AT in obesity. EndoMT in vitro resulted in production of EV that transferred some of the functional and metabolic features to recipient naïve EC. This result suggests that functional and molecular features of EC that underwent EndoMT in vivo can be disseminated in a paracrine or endocrine fashion and may induce endothelial dysfunction in distant vascular beds.

TGF-β-Induced Endothelial to Mesenchymal Transition in Disease and Tissue Engineering

“…Furthermore, via VE-cadherin lineage tracing in mice, EndMT was also shown to be involved in the transformation of ECs into white and brown fat cells (Tran et al, 2012). Recent manuscripts identified that microvascular ECs within adipose tissue in patients with obesity undergo EndMT, thereby modifying their secretome and enhancing systemic inflammation (Haynes et al, 2019). ECs isolated from tumor vessels can undergo EndMT to subsequently differentiate into adipocytes, pericytes, and SMCs (Huang et al, 2015), which suggests that artificially modified EndMT-derived cells may be useful to induce tissue repair in a paracrine manner.…”

Integration of Functional Imaging, Cytometry, and Unbiased Proteomics Reveals New Features of Endothelial-to-Mesenchymal Transition in Ischemic Mitral Valve Regurgitation in Human Patients

“…Some groups already provide hypotheses on extracellular vesicle (EV)-mediated EMT, predominantly in the context of cancer ( 38 , 39 ), but this regulation has never been established in valve EndMT. Nevertheless, human endothelial cells that underwent EndMT secreted three-times more EVs than control endothelial cells ( 40 ). Proteomic analysis of EV content showed enrichment in inflammatory and immune-related proteins ( 40 ).…”

“…Nevertheless, human endothelial cells that underwent EndMT secreted three-times more EVs than control endothelial cells ( 40 ). Proteomic analysis of EV content showed enrichment in inflammatory and immune-related proteins ( 40 ). These results could partially explain the similar profile of biological process enrichment we observed in leaflets with a high rate of EndMT.…”

Endothelial Extracellular Vesicles: From Keepers of Health to Messengers of Disease

“…Neointimal lesions exhibit shear stress-induced EndMT [ 27 ]. EndMT also contributes to maladaptive remodeling in the microvascular endothelium of obese adipose tissue (AT) in humans, leading to a loss of barrier function and angiogenic capacity [ 28 ]. In proliferative diabetic retinopathy, pathologic differentiation within the lymphatic endothelium may drive aberrant neovascularization and ischemia [ 29 ].…”

“…EVs obtained from adipose tissue of patients undergoing bariatric surgery were found to contain protein and miRNA cargo that reflect the proinflammatory signatures of their parent cells. These EVs have been shown to induce EndMT in adipose microvascular endothelial cells in vitro [ 28 ]. EVs derived from murine adipocyte cells exposed to the proinflammatory cytokine TNFα, induced an increase in markers consistent with EndMT in HUVECs along with increased leukocyte attachment [ 87 ].…”