PB0845 - Dissecting the impact of reactive oxygen species during macrophage differentiation in atherosclerosis

Monday, June 24, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

Laura Boccuni, PhD

Postdoctoral researcher
Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria
Vienna, Wien, Austria

Co-Author(s)

MS

Manuel Salzmann

Postdoctoral research
Medical University of Vienna
Vienna, Wien, Austria
FM

Frieda Marka

PhD student
Medical University of Vienna
Vienna, Wien, Austria
SS

Stefan Stojkovic

Physician
Department of Internal Medicine II/ Cardiology, Medical University of Vienna
Vienna, Wien, Austria
T�

Tiit Örd

Senior Researcher
University of Eastern Finland, A.I.Virtanen Institute for Molecular Sciences, Kuopio, Finland
Kuopio, Pohjois-Savo, Finland
MK

Minna Kaikkonen

Professor
University of Eastern Finland, A.I.Virtanen Institute for Molecular Sciences, Kuopio, Finland
Kuopio, Pohjois-Savo, Finland
JW

Johann Wojta

Professor
Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria
Vienna, Wien, Austria
PH

Philipp Hohensinner

Principal Investigator
Medical University Vienna, Center for Biomedical Research and Translational Surgery
Vienna, Wien, Austria

Background: Atherosclerosis is a condition caused predominantly by the accumulation of lipids in the artery walls. Excessive generation of reactive oxygen species (ROS) has been implicated as key process of atherosclerosis, leading to oxidation and aggregation of low-density lipoprotein (LDL). Ox-LDL are then phagocytosed by macrophages that become “foam cells” and accumulate contributing to formation of plaques and eventually rupture causing severe complications.

Aims: In this project we aim to investigate the effect of ROS on macrophages in vitro by identifying the pathways involved and understand their role during atherosclerosis in vivo.

Methods: To mimic the oxidative environment of the plaques, human monocyte-derived macrophages (MDM) were differentiated and polarized in vitro and challenged with either H2O2, for general ROS or DMNQ, for mitochondrial-specific ROS. The resulting phenotype was analysed by ELISA, flow cytometry, immunofluorescence and ATAC-seq. In vivo, ApoE-/- mice fed with high fat diet (HFD) and human atherosclerotic plaque samples were used.

Results: Our data revealed that MDM responded differently to ROS on a chromatin level, with H2O2 negatively regulating the chromatin landscape of inflammatory genes and DMNQ increasing chromatin accessibility at STAT5 target genes. Despite the potential anti-inflammatory effect of H2O2, we observed a strong activation of NLRP3 inflammasome, required for atherogenesis. Re-analysis of scATAC-seq and scRNA-seq data from human atherosclerotic lesions revealed up-regulation of STAT5 target genes mainly in lipid-associated macrophages. STAT5 phosphorylation was increased by DMNQ in proinflammatory-polarized MDM and its inhibition decreased oxLDL-induced foam cell formation. OxLDL-induced phagocytosis and lipid uptake were also decreased in STAT5-/- macrophages. In vivo, STAT5 activation was gradually increased during atherosclerosis progression and highly correlated with foam cells formation and ROS-induced mitochondrial oxidative damage.

Conclusion(s): Within the atherosclerotic lesion we could especially observe a phenotype mimicked by DMNQ treatment in vitro suggesting that the predominant source of ROS stress during progression of atherosclerosis are mitochondria.