Endothelial cell dysfunction as a novel therapeutic target in atherosclerosis

Estrogen receptor β-dependent Notch1 activation protects vascular endothelium against tumor necrosis factor α (TNFα)-induced apoptosis

Unlike age-matched men, premenopausal women benefit from cardiovascular protection. Estrogens protect against apoptosis of endothelial cells (ECs), one of the hallmarks of endothelial dysfunction leading to cardiovascular disorders, but the underlying molecular mechanisms remain poorly understood. The inflammatory cytokine TNFα causes EC apoptosis while dysregulating the Notch pathway, a major contributor to EC survival. We have previously reported that 17β-estradiol (E2) treatment activates Notch signaling in ECs. Here, we sought to assess whether in TNFα-induced inflammation Notch is involved in E2-mediated protection of the endothelium. We treated human umbilical vein endothelial cells (HUVECs) with E2, TNFα, or both and found that E2 counteracts TNFα-induced apoptosis. When Notch1 was inhibited, this E2-mediated protection was not observed, whereas ectopic overexpression of Notch1 diminished TNFα-induced apoptosis. Moreover, TNFα reduced the levels of active Notch1 protein, which were partially restored by E2 treatment. Moreover, siRNA-mediated knockdown of estrogen receptor β (ERβ), but not ERα, abolished the effect of E2 on apoptosis. Additionally, the E2-mediated regulation of the levels of active Notch1 was abrogated after silencing ERβ. In summary, our results indicate that E2 requires active Notch1 through a mechanism involving ERβ to protect the endothelium in TNFα-induced inflammation. These findings could be relevant for assessing the efficacy and applicability of menopausal hormone treatment, because they may indicate that in women with impaired Notch signaling, hormone therapy might not effectively protect the endothelium.

Relaxin-2 in Cardiometabolic Diseases: Mechanisms of Action and Future Perspectives

Despite the great effort of the medical community during the last decades, cardiovascular diseases remain the leading cause of death worldwide, increasing their prevalence every year mainly due to our new way of life. In the last years, the study of new hormones implicated in the regulation of energy metabolism and inflammation has raised a great interest among the scientific community regarding their implications in the development of cardiometabolic diseases. In this review, we will summarize the main actions of relaxin, a pleiotropic hormone that was previously suggested to improve acute heart failure and that participates in both metabolism and inflammation regulation at cardiovascular level, and will discuss its potential as future therapeutic target to prevent/reduce cardiovascular diseases.

Gestational Diabetes Alters Functions in Offspring's Umbilical Cord Cells With Implications for Cardiovascular Health

Because noncommunicable diseases such as type 2 diabetes mellitus have their roots in prenatal development and conditions such as maternal gestational diabetes mellitus (GDM), we aimed to test this hypothesis in primary cells derived from the offspring of mothers with GDM compared with control subjects. We have assessed primary umbilical cord-derived cells such as human umbilical vein endothelial cells (HUVECs) and Wharton's jelly-derived mesenchymal stem cells from the offspring of mothers with and without GDM. We have compared the primary isolates in cell-based assays measuring proliferation, mitochondrial oxygen consumption, and the ability to support blood vessel growth. We conducted gene expression microarray studies with subsequent pathway analysis and candidate gene validation. We observed striking differences between the two groups, such as lower metabolic rates and impairment of endothelial tube formation in cells with GDM background. HUVECs from subjects with maternal GDM have lower expression of the antiapoptotic protein BCL-xL, suggesting compromised angiogenic capabilities. Comparative gene expression analysis revealed blood vessel formation as a major pathway enriched in the GDM-derived HUVECs with the surface marker CD44 as a gene underexpressed in the GDM group. Functional validation of CD44 revealed that it regulates tube formation in HUVECs, thereby providing insights into a pathway imprinted in primary umbilical cord-derived cells from GDM offspring. Our data demonstrate that primary cells isolated from the umbilical cord of offspring born to mothers with GDM maintain metabolic and molecular imprints of maternal hyperglycemia, reflecting an increased risk for cardiovascular disease later in life.

Upregulation of TH/IL-17 Pathway-Related Genes in Human Coronary Endothelial Cells Stimulated with Serum of Patients with Acute Coronary Syndromes

BACKGROUND

Inflammation plays an essential role in the development and complications of atherosclerosis plaques, including acute coronary syndromes (ACS). Indeed, previous reports have shown that within the coronary circulation of ACS patients, several soluble mediators are released. Moreover, it has been demonstrated that endothelial dysfunction might play an important role in atherosclerosis as well as ACS pathophysiology. However, the mechanisms by which these soluble mediators might affect endothelial functions are still largely unknown. We have evaluated whether soluble mediators contained in serum from coronary circulation of ACS patients might promote changes of gene profile in human coronary endothelial cells (HCAECs).

METHODS

HCAECs were stimulated in vitro for 12 h with serum obtained from the coronary sinus (CS) and the aorta (Ao) of ACS patients; stable angina (SA) patients served as controls. Gene expression profiles of stimulated cells were evaluated by microarray and real-time PCR.

RESULTS

HCAECs stimulated with serum from CS of ACS patients showed a significant change (upregulation and downregulation) in gene expression profile as compared with cells stimulated with serum from CS of SA patients. Moreover, ad hoc sub analysis indicated the upregulation of Th-17/IL-17 pathway-related genes.

CONCLUSION

This study demonstrates that, in ACS patients, the chemical mediators released in the coronary circulation might be able to perturb coronary endothelial cells (ECs) modifying their gene profile. These modified ECs, through downregulation of protective gene and, mainly, through upregulation of gene able to modulate the Th-17/IL-17 pathway, might play a key role in progression of coronary atherosclerosis and in developing future acute events.

Reduced Activity of the Aortic Gamma-Glutamyltransferase Does Not Decrease S-Nitrosoglutathione Induced Vasorelaxation of Rat Aortic Rings

Aims: Gamma-glutamyl transferase (GGT), an enzyme present on the endothelium, is involved in the release of nitric oxide (NO) from S-nitrosoglutathione (GSNO) and in the GSNO-induced vasodilation. Endogenous GSNO is a physiological storage form of NO in tissues while exogenous GSNO is an interesting candidate for compensating for the decreased NO bioavailability occurring during cardiovascular diseases. We investigated in a rat model of human hypertension, the spontaneous hypertensive rat (SHR), submitted or not to high salt diet, whether a decreased vascular GGT activity modifies the vasorelaxant effect of GSNO.

Methods: Thoracic aortic rings isolated from male SHR and Wistar Kyoto rats (WKY) aged 20–22 weeks—submitted or not for 8 weeks to a high salt diet (1% w/v NaCl in drinking water) were pre-constricted with phenylephrine then submitted to concentration-vasorelaxant response curves (maximal response: E_max; pD₂) to carbachol or sodium nitroprusside to evaluate endothelial dependent or independent NO-induced vasodilation, or GSNO (exogenous NO vasodilation depending from the endothelial GGT activity). GGT activity was measured using a chromogenic substrate in aortic homogenates. Its role in GSNO-induced relaxation was assessed following inhibition of the enzyme activity (serine-borate complex). That of protein disulfide isomerase (PDI), another redox sensitive enzyme involved in GSNO metabolism, was assessed following inhibition with bacitracin.

Results: Aortic GGT activity (18–23 μmol/min/mg of tissue in adult WKY) decreased by 33% in SHR and 45% in SHR with high salt diet. E_max and pD₂ for sodium nitroprusside were similar in all groups. E_max for carbachol decreased by −14%, reflecting slight endothelial NO-dependent dysfunction. The GSNO curve was slightly shifted to the left in SHR and in SHR with high salt diet, showing a small enhanced sensitivity to GSNO. Involvements of GGT, as that of PDI, in the GSNO effects were similar in all groups (pD₂ for GSNO −0.5 to −1.5 following enzymatic inhibition).

Conclusion: Hypertension is associated with a decreased aortic GGT activity without decreasing the vasorelaxant effects of GSNO, whose bioactivity may be supplemented through the alternative enzymatic activity of PDI.