Universität zu Köln

Muders, David Paul ORCID: 0009-0009-5271-2660 (2024). MPO-mediated monocyte and macrophage activation upon myocardial infarction. PhD thesis, Universität zu Köln.

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Abstract

Acute myocardial infarction is one of the major health burdens in western hemisphere and has a high mortality1–4. Plasma levels of the polymorphonuclear neutrophil (PMN)-derived enzyme myeloperoxidase (MPO) have been shown to correlate with the prognosis and severity of myocardial infarction5–7. Apart from its capacity to catalyse the generation of highly reactive oxygen species (ROS) MPO has been shown to attract and activate PMN8. However, its effect on circulating monocytes and infiltrating macrophages, which are typically attracted by PMN and which are major effector cells of myocardial structural remodelling after infarction has never been tested. Herein we evaluate the role of MPO on monocyte and macrophage activation in vitro and in vivo and finally transfer our observations to a murine model of myocardial infarction. Peritoneal macrophages were harvested after thioglycolate stimulation in wild-type (WT) and MPO-deficient (Mpo-/-) mice. mRNA analysis by quantitative Realtime PCR revealed enhanced macrophage activation as assessed by increased expression of TNF-α in cells from WT - compared to Mpo-/- animals. Similarly, bone marrow derived macrophages (BMDM) harvested from WT mice showed increased mRNA expression of the proinflammatory cytokines iNOS, TNF-α, interleukin 6 and interleukin 23 upon 24 h of MPO treatment. In vivo, intraperitoneal injection of MPO in Mpo-/- mice resulted in a marked increase in peritoneal leukocyte recruitment compared to injection of saline. Flow cytometric differentiation of cells revealed an increased percentage of macrophages after MPO-injection. To confirm our results in a disease model, hearts from WT-and Mpo-/- mice were harvested 3 days after permanent LAD ligation and macrophage infiltration was assessed by immunohistochemical F4/80 stainings. Mpo-/- mice showed reduced macrophage infiltration in the infarct- and peri-infarct area as compared to WT animals. To figure out whether increased macrophage-infiltration in WT-mice is a result of increased infiltration or a result of eased mobilization of monocytes from the spleen, animals were ligated and spleens and blood were harvested 1d after LAD. Blood monocytes were analysed via flow cytometry and splenic monocytes were quantified via immunohistochemical CD11b stainings. Blood monocytes showed no significant difference in distribution of Ly6Chi- and Ly6Clo-monocytes between the groups, but splenic mobilisation was significantly decreased in Mpo-/- mice.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Muders, David Paul davidmuders@gmx.de orcid.org/0009-0009-5271-2660 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-720794
Date:	2024
Language:	English
Faculty:	Faculty of Medicine
Divisions:	Faculty of Medicine > Innere Medizin > Klinik III für Innere Medizin - Kardiologie, Pneumologie, Angiologie und internistische Intensivmedizin
Subjects:	Medical sciences Medicine
Uncontrolled Keywords:	Keywords Language Myeloperoxidase English Myocardial infarction English Monocyte English Macrophage English
Date of oral exam:	24 November 2023
Referee:	Name Academic Title Adam, Matti Privatdozent Dr. med. Niessen, Carien Universitätsprofessorin PhD
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/72079