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Epigallocatechin Gallate (EGCG) Modulates Senescent Endothelial Cell-Monocyte Communication in Age-Related Vascular Inflammation

ABSTRACT: Aging significantly affects intercellular communication between vascular endothelial cells (ECs) and hematopoietic cells, leading to vascular inflammation and age-associated diseases. This study determined how senescent ECs communicate with monocytes, whether extracellular vesicles (EVs) released from senescent ECs affect monocyte functions, and investigated the potential for epigallocatechin-3-gallate (EGCG), a flavonoid in green tea, to reverse these effects. Human umbilical vein endothelial cells (HUVECs) were treated with Etoposide (10 µM, 24h) to induce senescence, followed by EGCG (100 µM, 24h) treatment to evaluate its potential as a senotherapeutic agent. The interaction between ECs and monocytes was analyzed using a co-culture system and direct treatment of monocytes with EC-derived EVs. EGCG reduced senescence-associated phenotypes in ECs, as evidenced by decreased senescence-associated (SA)-β-Gal activity and reversal of Etoposide-induced senescence markers. Monocytes co-cultured with EGCG-treated senescent ECs showed decreased pro-inflammatory responses compared to those co-cultured with untreated senescent ECs. Additionally, senescent ECs produced more EVs than non-senescent ECs. EVs from senescent ECs enhanced lipopolysaccharide (LPS)-induced pro-inflammatory activation of monocytes, whereas EVs from EGCG-treated senescent ECs mitigated this activation, maintaining monocyte activation at normal levels. Our findings reveal that EGCG confers anti-senescent effects via modulation of the senescent EC secretome (including EVs) with the capacity to modify monocyte activation. These findings suggest that EGCG could act as a senotherapeutic agent to reduce vascular inflammation related to aging.

ORGANISM(S): Homo sapiens

PROVIDER: GSE286438 | GEO | 2025/01/18

REPOSITORIES: GEO

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Project description:ABSTRACT Rationale Premature senescence is conducive to aging and cardiovascular diseases. Nrf2 transcription factor, the master orchestrator of adoptive response to cellular stress, has been implicated in regulation of premature senescence in fibroblasts, neural and mesenchymal stem cells by transactivation of antioxidant gene expression. However, as we show here, human primary endothelial cells (ECs) devoid of Nrf2 and murine Nrf2 transcriptional knockout (tKO) aortas are senescent but do not encounter oxidative stress and damage, what contradicts this mechanism. Moreover, a molecular switch between normal, senescent and apoptotic fate remains unknown. Objective To elucidate the mechanism of Nrf2-related premature senescence of vascular system, to understand why Nrf2 deregulation does not cause oxidative stress exclusionary in ECs and to indicate a molecular switch determining ECs fate. Methods and Results Herein we evidence that ECs deficient in Nrf2 protein, or with limited Nrf2 activity in shear stress conditions, exhibit excessive S-nitrosylation of proteins. It is also a characteristic of Nrf2 tKO murine aortas, as determined by biotin switch assay in situ. Mass spectrometry analysis reveals that NOX4 is S-nitrosylated exclusively in ECs devoid of Nrf2. A functional role of S-nitrosylation is protection of ECs from death by inhibition of NOX4-mediated oxidative damage. As a result Nrf2-deficient ECs preserve oxidative balance but are redirected to premature senescence. The same phenotype is seen in Nrf2 tKO aortas. These effects are mediated by Keap1, a direct binding partner of Nrf2 and repressor of its transcriptional activity, remaining in cytoplasm unrestrained by Nrf2. S-nitrosylation, followed by senescence, can also be triggered in smooth muscle cells (SMCs) by EC-derived paracrine induction of iNOS. Conclusions Collectively, Keap1-dependent S-nitrosylation of NOX4 hampers oxidative detriment in ECs with disturbed Nrf2 signaling and may provide defence in the adjacent aortic cells. Overabundance of unrestrained Keap1 in the cytoplasm determines fate of ECs.

Project description:Atherosclerosis represents an age-related disease, which remains one of the leading cause of deaths in developed countries. It begins with a local deposition of lipid in the innermost part of the artery – intima. Thereafter a number of immune cells are attracted and infiltrate into the artery wall, where, together with endothelia and smooth muscle cells, form an atherosclerotic plaque (Libby, 2008). Thus, atherosclerosis is considered as an inflammatory disease, characterized by intense immunological activity (Libby P, 2012). One of the main risk factor for atherosclerosis is aging. It was demonstrated that there is an accumulation of senescent cells within atherosclerotic plaque (..). Accordingly, vascular smooth muscle cells (VSMCs) derived from the lesion demonstrate a phenotype characteristic for senescent cells: diminished proliferative potential, shorter telomeres, increased number of DNA damage and upregulation of SA-β-gal activity (Gorenne, 2006; Matthes, 2006, Mahomoudi, 2008). Accumulation of senescent VSMCs within the area of plaque development promotes its instability due to lack of proliferation and impaired production of extracellular matrix, both leading to weakening of fibrous cap (Gorenne, 2006). This has been further confirmed by the observation, that elimination of senescent cells in the atherosclerosis-prone low-density lipoprotein receptor-deficient (Ldlr-/-) mice slowed down the disease progression (27789842). One of the most important feature of senescent cells, that has the biggest impact on tissue microenvironment, is their ability to secrete a number of cytokines, chemokines, matrix metalloproteinases and growth factors collectively known as the Senescence Associated Secretory Phenotype (SASP) (20078217, 28165648). Apart from soluble factors, senescent cells secret also an increased number of extracellular vesicles (EVs), research of which has only recently begun (32461143). EVs are small membranous vesicles that can be categorized based on their size and origin, into: exosomes, microvesicles and apoptotic bodies. EVs play crucial role as carriers of proteins, different types of RNA and DNA, lipids and metabolites that, take part in intercellular communication (23420871). They were shown to participate in many physiological but also pathological conditions. Studies performed over the last decade proved that EVs affect atherosclerosis progression at different stages by several distinct mechanisms (as reviewed by Knokhot, 2020, 33261815). The increased concentrations of EVs have been found in plasma of patients suffering from cardiovascular diseases as well as in atherosclerotic plaque itself (Yin, 2015, 26142082; Rautou, 2011, 21852557). However, the role of EVs derived from senescent cells in atherosclerosis, particularly in the context of the plaque development, remains unknown. The functioning of immune cells within atherosclerotic plaque is modulated by local milieu. Thus, senescent cells present in the lesion can influence plaque development by non-cell autonomous mechanism. Indeed, recently it was demonstrated that SASP factors secreted by senescent VSMCs promote recruitment of monocytes, induce expression of adhesion receptors on endothelial cells and activate adjacent normal VSMCs, promoting inflammation in the plaque (Gardner, 2015). However, the role of EVs in this context has not been studied. Thus, we have undertaken research aimed at investigating the role of senescent cell derived EVs on immune cells activity. To this end, we isolated and characterized the EVs secreted by human VSMCs undergoing senescence. We performed unbiased quantitative proteomic analysis of both soluble and insoluble SASP components. Moreover, we analyzed the influence of EVs derived from senescent and non-senescent cells on T lymphocytes and monocytes. Altogether our studies revealed that EVs produced by senescent VSMCs strengthen inflammatory response of the immune cells, what would have a tremendous significance in atherosclerotic plaque development.

Project description:Vascular calcification and increased extracellular matrix (ECM) stiffness are hallmarks of vascular ageing. Sox9 (SRY-Box Transcription Factor 9) is a master regulator of chondrogenesis, also expressed in the vasculature, that has been implicated in vascular smooth muscle cell (VSMC) osteo-chondrogenic conversion. Here, we investigated the relationship between vascular ageing, calcification and Sox9-driven ECM regulation in VSMCs. Immunohistochemistry in human aortic samples showed that Sox9 was not spatially associated with vascular calcification but correlated with the senescence marker p16. Analysis of Sox9 expression in vitro showed it was mechanosensitive with increased expression and nuclear translocation in senescent cells and on stiff matrices. Manipulation of Sox9 via overexpression and depletion, combined with atomic force microscopy (AFM) and proteomics, revealed that Sox9 regulates ECM stiffness and organisation by orchestrating changes in collagen expression and reducing VSMC contractility, leading to the formation of an ECM that mirrored that of senescent cells. These ECM changes promoted phenotypic modulation of VSMCs whereby senescent cells plated onto ECM synthesized from cells depleted of Sox9 returned to a proliferative state, while proliferating cells on a matrix produced by Sox9 expressing cells showed reduced proliferation and increased DNA damage, reiterating features of senescent cells. Procollagen-lysine, 2-oxoglutarate 5-dioxygenase 3 (LH3) was identified as a Sox9 target, and key regulator of ECM stiffness. LH3 is packaged into extracellular vesicles (EVs) and Sox9 promoted EV secretion, leading to increased LH3 deposition within the ECM. These findings identify cellular senescence and Sox9 as a key regulators of ECM stiffness during VSMC ageing and highlight a crucial role for ECM structure and composition in regulating VSMC phenotype. We identify a positive feedback cycle whereby cellular senescence and increased ECM stiffening promote Sox9 expression which drives further ECM modifications that act to accelerate vascular stiffening and cellular senescence.

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Epigallocatechin Gallate (EGCG) Modulates Senescent Endothelial Cell-Monocyte Communication in Age-Related Vascular Inflammation

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