Athanassopoulos, P.

Blood dendritic cell levels and phenotypic characteristics in relation to etiology of end-stage heart failure: Implications for dilated cardiomyopathy (Article)

2009-01-09T00:00:00Z

Background: Dysregulation of dendritic cell (DC) mediated immune responses towards auto-antigens, is considered an important feature in the maintenance of experimentally induced heart failure (HF). In order to evaluate the role of blood DCs in cardiomyopathies of different origins, we examined myeloid (mDC) and plasmacytoid (pDC) subset levels and maturation characteristics, according to HF severity and etiology in humans. Methods: Absolute numbers of mDCs and pDCs in 12 New York Heart Association (NYHA) class-II, 28 NYHA class III-IV HF patients and 18 healthy controls, were studied by 4-colour whole blood flow cytometry. Results: End-stage (NYHA III-IV) HF patients had comparable circulating DC subset levels to NYHA-II patients and controls. However, within the NYHA III-IV group total DC levels in patients with non-ischemic dilated cardiomyopathy (DCM) were higher (P < 0.001) than in patients with coronary artery disease (CAD), hypertrophic cardiomyopathy (HCM) or other HF etiology. This was due to a significant increase of primarily mDCs (P < 0.0001) and to a lesser extent of pDCs (P < 0.05) in idiopathic DCM patients, independent of systolic or diastolic cardiac dysfunction. Maturation marker CD83 and lymphoid homing chemokine receptor CCR7 surface expression was enhanced only on mDCs, but not pDCs from DCM patients (P < 0.05), compared to patients with CAD, HCM or other underlying cardiac pathophysiology. Conclusions: Total blood DC levels in end-stage HF are elevated in patients with DCM. Whole blood DC characterisation may lead to new insights into the pathophysiology of idiopathic DCM in humans.

Peripheral blood manipulation significantly affects the result of dendritic cell monitoring (Article)

2007-04-01T00:00:00Z

It has been postulated that the plasmacytoid/myeloid dendritic cell ratio (pDC/mDC) reflects immune reactivity, and can therefore be used to monitor transplant recipients. We investigated the influence of Ficoll-Paque separation and PBMC cryopreservation on the pDC/mDC ratio and the expression of maturation markers, e.g. chemokine receptors (CKRs) CCR7, CXCR4, and CCR5, in comparison to fresh blood cells. Fractions of pDCs and mDCs, and CKR expression were measured by flow cytometry in fresh blood, in Ficoll-isolated PBMCs and in cryopreserved PBMCs from healthy individuals and kidney transplant recipients. Ficoll-isolation of PBMCs resulted in higher pDC/mDC ratios in both groups compared to fresh blood cells resulting from a relatively large increase in pDCs compared to mDCs. The pDC/mDC ratio increased further after cryopreservation of PBMCs from kidney transplant recipients. Ficoll-isolation and cryopreservation of PBMCs affected the proportion of mDCs and pDCs positive for CKRs, and their expression levels resulting in a more mature phenotype. In conclusion, the pDC/mDC ratio and pDC or mDC maturation status based on CKR expression, is dependent on manipulation of PBMCs. Therefore, fresh blood is preferable for monitoring purposes in transplant patients, as only these cells reflect the in vivo immune-status of patients accurately.

Chemokine-receptor Mediated Dendritic Cell and T-cell Recirculation in Heart Failure and Transplantation (Doctoral Thesis)

2006-06-28T00:00:00Z

Heart failure (HF) is a complex clinical syndrome characterized by immune activation in its chronic stages. By different forms of cardiac dysfunction, infiltration of failing human myocardium with effector leukocytes through low-grade inflammation, leads to deterioration of clinical condition to endstage HF. The only available permanent therapeutic option for patients with end-stage cardiac disease is heart transplantation (HTx). Allo-antigen dependent immune cell activation and recirculation determine graft outcome, with heart allograft rejection remaining a severe complication after HTx. For years the international transplantation community attempts to improve patient survival and prevent graft loss. In this context, identifying patients at high risk for rejection or even predicting acute cardiac rejection (AR) would be important, as appropriate adjustments in immunosuppressive regimens may avoid over-immunosuppression related complications after clinical HTx. In this thesis, we attempted to clarify the role of chemokines and chemokine receptors in leukocyte recirculation during end-stage HF and rejection after HTx. Trafficking of dendritic cell (DC) and T-cell subsets received our particular attention, because their interaction critically determines the type of immune reactivity elicited in chronic disease and transplantation. Chapter 1, provides a general introduction on the migratory routes followed by DCs and T-cells, based on chemokines and their receptors. Known chemotactic pathways of leukocyte activation and infiltration as well as their role in the pathogenesis of HF and heart allograft rejection are presented. A description of the objectives of our studies is also included.