PhD Scientific Days 2023

Translational Medicine I.

The detrimental synergistic effect of hypoxia and complement MASP-1 in the atherosclerosis-related diseases, on endothelial cell model

Text of the abstract

Introduction:
Hypoxia and hypoxia/reoxygenation are direct pathogenic components in stroke and acute myocardial infarction (AMI) developing as a consequence of atherosclerosis. The complement lectin pathway (CLP) is known to play a crucial role both in atherosclerosis and in atherosclerosis-related diseases. We previously demonstrated that Mannan-binding lectin-associated serine protease-1 (MASP-1), the most abundant enzyme of the CLP induces an inflammatory phenotype of endothelial cells by cleaving Protease Activated Receptors (PARs).
Aims:
There is no data whether hypoxia and MASP-1 can potentiate each other’s effects, therefore, we aimed to investigate the possible synergism between them.
Methods:
As a hypoxic endothel model we used CoCl2 treated HUVECs or a 1% O2 hypoxic incubator. Adhesion molecules and cytokines were detected with cellular or sandwich ELISA. Signalization pathways were studied with immuno-fluorescence microscopy; Ca2+ mobilization with fluorescence microscopy using Fluo4-AM Ca-sensitive dye, PAR gene expression with qPCR and permeability changes with the XPerT method. Statistical analysis was performed by GraphPad Prism 7.0.
Results:
E-selectin was synergistically upregulated by hypoxia and MASP-1, whereas MASP-1 induced VCAM-1 expression could be inhibited by hypoxia. Hypoxia increased ICAM-1, while decreased ICAM-2 expression. Hypoxia and MASP-1 elevated GRO and IL-8 production, and increased endothelial permeability without potentiating each other’s effects. Hypoxia and MASP-1 synergistically activated the Ca2+, CREB and NFκB signalization pathways. CoCl2 time-dependently upregulated PAR2 gene expression. C1 inhibitor, a natural inhibitor of MASP-1 inhibited the hypoxia enhancing effect of MASP-1.
Conclusion:
Hypoxia potentiates the effect of MASP-1 on endothelial cells, at least partially, by increasing PAR2 expression. This results in the strong synergism between the two agents observed at the level of signalization pathways, adhesion molecules and cytokines, which may contribute to the development of the strong neutrophil infiltration well-known in the acute phase of stroke and AMI. This raises the role of MASP-1 as a drug target in the acute phase of atherosclerosis-related diseases.
Funding:
The study was supported by OTKA K115623, ELKH-TKI Immunothrombosis, and the Richter Gedeon Centenary Foundation Research Student Scholarship.