PB1263 - Evidence for mitochondrial dysfunction in blood-derived endothelial colony forming cells isolated from patients with antiphospholipid syndrome

Tuesday, July 12, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

LK

Lida Kabir, MRes

Research Postgraduate
National Heart and Lung Institute, Imperial College London
London, England, United Kingdom

Co-Author(s)

RM

Robert T. Maughan

Research Associate
National Heart and Lung Institute, Imperial College London
London, England, United Kingdom
Koralia Paschalaki, MD, PhD

Respiratory physician - Clinical Research Fellow
National Heart and Lung Institute, Imperial College London
London, England, United Kingdom
Anna M. Randi, MD,PhD

Professor of Cardiovascular Medicine
Imperial College London
London, England, United Kingdom
DC

David Carling

Professor of Biochemistry
MRC London Institute of Medical Sciences, Imperial College London
London, England, United Kingdom
DA

Deepa J. Arachchillage, MD

consultant haematologist
Imperial College London
London, England, United Kingdom
JM

Justin C. Mason

Professor of Vascular Rheumatology
National Heart and Lung Institute, Imperial College London
London, England, United Kingdom
CP

Charis Pericleous

Research Fellow
National Heart and Lung Institute, Imperial College London
London, England, United Kingdom

Background: Endothelial dysfunction is a critical event in antiphospholipid syndrome (APS), a systemic autoimmune disease characterised by the persistent presence of pathogenic antiphospholipid antibodies (aPL), thrombotic and obstetric complications. aPL activate endothelial and immune cells, tipping the haemostatic balance to an inflammatory and pro-coagulant state. Altered metabolism and mitochondrial function in patient-derived immune cells may contribute to APS pathogenesis but these mechanisms have yet to be explored in the endothelium.

Aims: To examine how aPL impact endothelial metabolism and mitochondrial function using ex vivo blood-derived endothelial colony forming cells (ECFCs) from patients with APS.

Methods: ECFCs were isolated from peripheral blood mononuclear cells (PBMCs) obtained from patients with APS (n=11; 5 with arterial thrombosis, 3 venous, 3 with both) and healthy controls (HC, n=11). Experiments were performed at passage 4-5. Protein expression was assessed by immunoblot, respiratory and glycolytic measurements using the Seahorse XFe96 Flux Analyzer, and mitochondrial network analysis by cytochrome c immunofluorescence. Non-parametric Mann-Whitney and Spearman’s data analysis was performed.

Results: Colony number per 10^7 PBMC seeded, time in culture to colony appearance and time to passage were similar between patient and control ECFC. Diminished basal mitochondrial respiration and OXPHOS-linked ATP production (oxygen consumption rate, p< 0.05) in APS ECFCs provides evidence for mitochondrial dysfunction; a tendency towards a glycolytic phenotype was also evident. OXPHOS immunoblot analysis correlated with basal respiration measurements (r=0.7, p=0.04). Concomitantly, we observed suppressed mitochondrial MnSOD expression along with reduced mitochondrial footprint and increased fragmentation of the endothelial mitochondrial network in APS versus HC ECFCs, indicating mitochondrial stress.

Conclusion(s): Perturbed mitochondrial energy homeostasis and increased glycolysis are pronounced in APS patient-derived ECFCs, signifying pathological metabolic reprogramming. Given the importance of mitochondria in endothelial homeostasis, dysfunctional mitochondria may contribute to the pro-coagulant and inflammatory features of endothelial dysfunction in APS.