Endothelial damage in major depression patients is modulated by SSRI treatment, as demonstrated by circulating biomarkers and an in vitro cell model

Abstract

There is a link between depression, cardiovascular events and inflammation. We have explored this connection through endothelial dysfunction, using in vivo and in vitro approaches. We evaluated circulating biomarkers of endothelial dysfunction in patients with major depression at their diagnosis (MD-0) and during antidepressant treatment with the selective serotonin reuptake inhibitor escitalopram, for 8 and 24 weeks (MD-8 and MD-24). Results were always compared with matched healthy controls (CON). We measured in vivo circulating endothelial cells (CECs) and endothelial progenitor cells (EPCs) in blood samples, and assessed plasma levels of soluble von Willebrand factor (VWF) and vascular cell adhesion molecule-1 (VCAM-1). CEC counts, soluble VWF and VCAM-1 were statistically elevated in MD-0 (P<0.01 versus CON) and gradually decreased during treatment. Conversely, EPC levels were lower in MD-0, tending to increase throughout treatment. In vitro studies were performed in human endothelial cells cultured in the presence of sera from each study group. Elevated expression of the inflammation marker intercellular adhesion molecule-1 and oxidative stress, with lower presence of endothelial nitric oxide synthase and higher reactive oxygen species production, were found in cells exposed to MD-0 sera (P<0.05 versus CON). These results were normalized in cells exposed to MD-24 sera. Thrombogenicity of extracellular matrices generated by these cells, measured as expression of VWF, tissue factor and platelet reactivity, showed non-significant differences. We provide a model of cultured endothelial cells reproducing endothelial dysfunction in naive patients with major depression, demonstrating endothelial damage and inflammation at diagnosis, and recovering with selective serotonin reuptake inhibitor treatment for 24 weeks.

Figure 1

Markers of endothelial damage in blood samples. Bar diagrams showing in vivo levels of markers of endothelial damage: circulating endothelial cells (CEC) and endothelial progenitor cells (EPC) in whole blood samples (a, b), and von Willebrand factor (VWF) and soluble vascular cell adhesion molecule-1 (sVCAM-1) in plasma samples (c, d). Graphs show levels of these markers in healthy controls (CON) and in major depression patients at the moment of diagnosis (MD-0), and after 8 and 24 weeks of antidepressant treatment (MD-8 and MD-24) with the selective serotonin reuptake inhibitor escitalopram. Results are expressed as mean±s.e.m. (n=12). *P<0.01 versus CON; ^#P<0.05 versus MD-0; ^§P<0.05 versus MD-8.

Figure 2

Production of reactive oxygen species (ROS) in cultured endothelial cells. (a) Representative fluorescence micrographs showing in vitro ROS production in cells grown with cell-culture media supplemented with sera from: healthy controls (CON) and major depression patients at the moment of diagnosis (MD-0), and after 8 and 24 weeks of antidepressant treatment (MD-8 and MD-24) with the selective serotonin reuptake inhibitor escitalopram (scale bar, 50 μm). (b) Bar diagrams summarizing quantification of fluorescence intensities, as fold-increase in the mean fluorescence intensity in each condition over the mean fluorescence measured in CON. Results are expressed as mean±s.e.m. (n=4 sera pools). *P<0.05 versus CON, ^#P<0.05 versus MD-0.

Figure 3

Expression of the oxidative stress marker eNOS within cultured endothelial cells. (a) Representative fluorescence micrographs showing in vitro intracellular eNOS in cells grown with cell-culture media supplemented with sera from: healthy controls (CON) and major depression patients at the moment of diagnosis (MD-0), and after 8 and 24 weeks of antidepressant treatment (MD-8 and MD-24) with the selective serotonin reuptake inhibitor escitalopram (scale bar, 50 μm). (b) Bar diagrams summarizing quantification of fluorescence intensities, as fold-increase in the mean fluorescence intensity in each condition over the mean fluorescence measured in CON. Results are expressed as mean±s.e.m. (n=4 sera pools). *P<0.05 versus CON, ^#P<0.05 versus MD-0. eNOS, endothelial nitric oxide synthase.

Figure 4

Expression of the inflammation marker intercellular adhesion molecule-1 (ICAM-1) on the surface of cultured endothelial cells and thrombogenicity of extracellular matrices generated by these cultured endothelial cells. (a) Representative fluorescence micrographs showing in vitro expression of ICAM-1 in the surface of endothelial cells grown with cell-culture media supplemented with sera from: healthy controls (CON) and major depression patients at the moment of diagnosis (MD-0), and after 8 and 24 weeks of antidepressant treatment (MD-8 and MD-24) with the selective serotonin reuptake inhibitor escitalopram (scale bar, 50 μm). (b) From left to right, bar diagrams summarizing quantification of fluorescence intensities from immunofluorescence studies showing ICAM-1 on the cell surface, and presence of VWF and tissue factor (TF) in extracellular matrices, expressed as fold-increase in the mean fluorescence intensity in each condition over the mean fluorescence measured in CON. Results are expressed as mean±s.e.m. (n=4 sera pools). *P<0.05 versus CON, ^#P<0.05 versus MD-0, ^§P<0.05 versus MD-8. VWF, von Willebrand factor.