Soluble endoglin modulates the pro-inflammatory mediators NF-kappa B and IL-6 in cultured human endothelial cells

34 p.-7 fig.Aims: Endoglin is a transmembrane glycoprotein, that plays an important role in regulating endothelium. Proteolytic cleavage of membrane endoglin releases soluble endoglin (sEng), whose increased plasma levels have been detected in diseases related to the cardiovascular system. It was proposed that sEng might damage vascular endothelium, but detailed information about the potential mechanisms involved is not available. Thus, we hypothesized that sEng contributes to endothelial dysfunction, leading to a pro-inflammatory phenotype by a possible modulation of the TGF-β and/or inflammatory pathways.Main methods: Human umbilical vein endothelial cells (HUVECs) and Human embryonic kidney cell line (HEK293T) were treated with different sEng concentration and time in order to reveal possible effect on biomarkers of inflammation and TGF-β signaling. IL6 and NFκB reporter luciferase assays, quantitative real-time PCR analysis, Western blot analysis and immunofluorescence flow cytometry were used.Key findings: sEng treatment results in activation of NF-κB/IL-6 expression, increased expression of membrane endoglin and reduced expression of Id-1. On the other hand, no significant effects on other markers of endothelial dysfunction and inflammation, including eNOS, peNOSS1177, VCAM-1, COX-1, COX-2 and ICAM-1 were detected.Significance: As a conclusion, sEng treatment resulted in an activation of NF-κB, IL-6, suggesting activation of pro-inflammatory phenotype in endothelial cells. The precise mechanism of this activation and its consequence remains to be elucidated. A combined treatment of sEng with other cardiovascular risk factors will be necessary in order to reveal whether sEng is not only a biomarker of cardiovascular diseases, but also a protagonist of endothelial dysfunction.This work was supported by grants from Czech Science Foundation (GACR 15-24015S,GAUK 1158413C, SVV/2016/260293 and SVV/2017/260414 to Petr Nachtigal), Ministerio de Economía y Competitividad of Spain (SAF2013-43421-R to Carmelo Bernabéu), Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER; ISCIIICB06/07/0038 and ER16PIAC707 to CB). CIBERER is an initiative of the Instituto de Salud Carlos III (ISCIII) of Spain supported by FEDER funds.Peer reviewe

Short title: endoglin, cholesterol and endothelial dysfunction

41 p.-7 fig.Objective: To investigate the effect of cholesterol (hypercholesterolemia/7- ketocholesterol) on endoglin expression and regulation with respect to endothelial/vascular dysfunction in vivo and in vitro.Approach and results: In vivo experiments were performed in two-month-old ApoE-/-/LDLR-/- female mice and their wild type C57BL/6J littermates. In in vitro experiments, Human Aortic Endothelial Cells (HAECs) were treated with 7-ketocholesterol (7K). ApoE-/-/LDLR-/- mice developed hypercholesterolemia accompanied by increased circulating levels of P-selectin and endoglin and a disruption of NO metabolism. Functional analysis of aorta demonstrated impaired vascular reactivity and Western blot analysis revealed downregulation of membrane Eng/Smad2/3/eNOS signaling in ApoE-/-/LDLR-/- mice. 7K increased endoglin expression via KLF6, LXR and NF-κB in HAECs. 7K-induced endoglin expression was prevented by the treatment with 2-hydroxypropyl-β-cyclodextrin, PHA-408 or by KLF6 silencing. 7K induced increased adhesion and transmigration of monocytic THP-1 cells, was prevented by endoglin silencing.Conclusions: Hypercholesterolemia altered endoglin expression and signaling, followed by endothelial/vascular dysfunction before formation of atherosclerotic lesions in ApoE-/-/LDLR- /- mice. By contrast, 7-ketocholesterol increased endoglin expression, and induced inflammation in HAECs, which was followed by an increased adhesion and transmigration of monocytes via endothelium, which was prevented by endoglin inhibition. Thus, we propose a relevant role for endoglin in endothelial/vascular dysfunction/inflammation when exposed to cholesterolThis work was supported by project EFSA-CDN (No. CZ.02.1.01/0.0/0.0/16_019/0000841) cofunded by ERDF, grants of Charles University Grant Agency, GAUK 1158413C, 1216217,Specific University Research SVV/2017/260414 and Czech Health Research Council (AZV CR17-31754A). CB was supported by grants from Consejo Superior de Investigaciones Cientificas(201420E039) and Centro de Investigacion Biomedica en Red de Enfermedades Raras(CIBERER; ISCIII-CB06/07/0038). CIBERER is an initiative of the Instituto de Salud Carlos III(ISCIII) of Spain supported by FEDER funds.Peer reviewe