| 1. |
- Bergström, Ida
(författare)
-
Pro- and anti-inflammatory actions in coronary artery disease : with focus on CD56+ T cells and Annexin A1
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- ¨The atherosclerotic process is considered to be driven by an imbalance between proand anti-inflammatory actions. Still, the inflammatory state in patients with coronary artery disease (CAD) remains to be clarified. Annexin A1 (AnxA1) is a glucocorticoidinduced protein which may have a key role in the anti-inflammatory response as a mediator of glucocorticoid effects.The general aim of this thesis was to deepen the knowledge of pro- and antiinflammatory mechanisms in CAD via phenotypic assessments of immune cell subsets, in particular CD56+ T cells, and exploration of AnxA1. The long-term goal is to reveal basic mechanisms that will lead to the development of biomarkers, which may be used for individualized treatment and monitoring.The AnxA1 protein was constitutively expressed in both neutrophils and peripheral blood mononuclear cells (PBMCs). However, it varied considerably across PBMC subsets, being most abundantly expressed in monocytes. The AnxA1 expression was also higher in CD56+ T cells than in CD56- T cells.The expression of total AnxA1 protein in neutrophils was higher in patients with stable angina (SA) compared with controls. However, this was not accompanied by altered neutrophil activation status. Instead, the neutrophils from patients exhibited an enhanced anti-inflammatory response to exogenous AnxA1, emphasizing the potential of AnxA1 as an inhibitor of neutrophil activity. Only patients with acute coronary syndrome (ACS) showed an increase in cell surface-associated AnxA1.CAD patients, independent of clinical presentation, had increased proportions of CD56+ T cells compared with controls, a phenomenon likely to represent immunological aging. The CD56+ T cells were found to exhibit a distinct proinflammatory phenotype compared with CD56- T cells. In all T cell subsets, the expression of cell surface-associated AnxA1 was significantly increased in ACS patients, while it tended to be increased in post-ACS patients. In addition, dexamethasone clearly inhibited activation of CD56+ T cells in in vitro assays, whereas AnxA1 did not. The findings highlight the need to clarify whether the role of AnxA1 is different in T cells than in innate immune cells.In PBMCs, the mRNA levels of AnxA1 were increased in CAD patients, particularly in ACS patients. Correspondingly, the monocytes in ACS patients exhibited increased AnxA1 protein levels, both totally and on the cell surface. However, only cell surface-associated AnxA1 in monocytes correlated with the glucocorticoid sensitivity of PBMCs ex vivo. We propose the expression of cell surfaceassociated AnxA1 to be a promising candidate marker of glucocorticoid sensitivity, which needs further investigations in larger cohorts and intervention trials. Furthermore, the fact that PBMCs in post-ACS patients exhibited pro-inflammatory activity but no increase in cell surface-associated AnxA1 allow us to speculate that the glucocorticoid action and/or availability might be insufficient in these patients.
|
|
| 2. |
- Jönsson, Simon, 1983-
(författare)
-
Leukocyte-derived matrix metalloproteinase-9 in patients with coronary artery disease : Associations with psychological stress and glucocorticoid sensitivity
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Inflammation is closely associated with development of atherosclerosis. The proteolytic enzyme matrix metalloproteinase (MMP)-9 is considered to play a prominent role in this process. MMP-9 has also been introduced as a marker for plaque vulnerability. Still, the possible mechanisms behind altered levels of MMP-9 and its tissue inhibitors (TIMPs) in patients with atherosclerotic disease remain unclear. The general aim of this thesis was to compare leukocyte-derived MMP-9 and TIMPs in patients with coronary artery disease (CAD) and healthy controls and to further relate the findings to psychological stress and glucocorticoid sensitivity.Levels of leukocyte-derived MMP-9 and TIMP-1 showed a significant difference between CAD patients and controls. Neutrophils in CAD patients were more prone to release MMP-9 and furthermore, PBMCs in patients expressed higher levels of MMP-9 and TIMP-1 and -2 mRNA than PBMCs in controls while there were no differences in plasma or serum levels. The increase in leukocyte-derived levels of MMP-9 and TIMPs indicate the presence of preactivated leukocytes in CAD.Inflammation has been proposed as a mechanistic link between cardiovascular risk and depressive symptoms. We investigated whether the overexpression of leukocyte-derived MMP-9 and TIMPs in CAD patients was associated with psychological factors. Patients exhibited sustained elevations in depressive symptoms, however, these symptoms were not related to any MMP-9 or TIMP variables. The findings suggest that overexpression of leukocyte-derived MMP-9 and TIMPs and elevated depressive scores represent two parallel phenomena in CAD.Chronic inflammation may be associated with reduced glucocorticoid sensitivity. We found that PBMCs in CAD patient expressed significantly increased levels of glucocorticoid receptor (GR)-α mRNA, whereas GR-β mRNA levels did not differ between patients and controls. Moreover, in ex vivo assays, dexamethasone efficiently suppressed MMP-9 and TIMPs equally or even more in patients compared to controls. The findings provide evidence for enhanced glucocorticoid sensitivity in CAD patients and also suggest that a state of relative hypocortisolism may contribute to the overexpression of leukocyte-derived MMP-9 and TIMPs.Lastly, we explored the release of MMP-9, TIMPs and cortisol in response to acute mental stress in CAD patients. Patients who exhibited a significant stress-induced increase in serum MMP-9 also exhibited an altered cortisol response. Moreover, the susceptibility to stressinduced increase in serum MMP-9 was associated with shorter leukocyte telomere length and atherosclerotic plaque burden. The findings highlight the existence of a high-risk group which may be in need of improved diagnostic and therapeutic strategies.
|
|
| 3. |
- Szymanowski, Aleksander, 1973-
(författare)
-
Detection of apoptosis in patients with coronary artery disease : Assessment of temporal patterns and potential sources
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The atherosclerotic process and its consequences are considered driven by an imbalance between pro- and ant-inflammatory actions. One contributing factor in this scenario is an altered regulation of apoptosis, which affects both immune, vascular and myocardial cells. The general aim of this thesis was to measure soluble markers of apoptosis in peripheral venous blood, in various clinical stages of coronary artery disease (CAD) and to further identify possible sources with specific focus on natural killer (NK) cell apoptosis and myocardial ischemia-reperfusion (IR)-injury.There was evidence of an increased apoptosis of NK cells, but not T cells, in the circulation of CAD patients. Spontaneous NK cell apoptosis and the cells´ sensitivity to oxidative stress in the form of oxidized lipids ex vivo, were increased. Findings were thus suggestive of an enhanced apoptosis contributing to the reduced NK cell activity seen in CAD. However, we could not verify that oxidative stress in the circulation was a driving force behind this loss.Soluble forms of the cell surface bound receptors of apoptosis include soluble (s) Fas and sFas ligand (L). They are detected in plasma and used as surrogate markers of apoptosis. Here we investigated the relationship between these markers and NK cell apoptosis and NK cell levels, in a 12 month longitudinal study on CAD patients. Plasma levels of sFasL correlated with increased susceptibility to NK cell apoptosis ex vivo but also with the levels of NK cells in the circulation after a coronary event. NK cells undergoing apoptosis ex vivo were also found to be a major source of sFasL themselves, indicating potential usefulness of sFasL in monitoring changes in NK cell levels.Apoptosis is suggested to be a key event in IR-injury, resulting in increased infarct size, left ventricular (LV) dysfunction, remodeling and heart failure. We investigated soluble markers of apoptosis in relation to these parameters in a ST-elevation myocardial infarction (STEMI) population. In addition to sFas and sFasL, we also measured tumor necrosis factor (TNF) receptor (R) I and II in this study. Acute phase levels of sTNFRI and sTNFRII, but not sFas or sFasL, correlated to cardiac MR (CMR) measures of infarct size and LV-dysfunction at 4 months after the ischemic event. Also, the soluble markers of apoptosis were correlated with matrix metalloproteinase (MMP)-2, a mechanistic trigger for cardiomyocyte apoptosis, further strengthening the role of apoptosis in IR-injury.Finally we explored the temporal patterns of soluble markers of apoptosis after an MI and, furthermore, investigated possible differences between patients presenting with a non(N)-STEMI versus STEMI. The sTNFRI/II and the sFas/sFasL pathways of apoptosis showed different temporal changes indicating diverse roles of these two systems. NSTEMI and STEMI patients however, shared these temporal patterns pointing to apoptosis as equally involved in either infarct type. Furthermore sTNFRs, but not sFas/sFasL correlated to levels of cytokine interleukin (IL)-6 illustrating the overlapping role TNF signaling in inflammation and apoptosis, while again suggesting differences between the TNF and the Fas/FasL systems during myocardial IR--‐injury.
|
|
