Research activities

1. Bioactive lipids and inflammation in the vascular wall

Inflammatory reactions in endothelial cells are regulated primarily through activation of inflammatory genes encoding adhesion molecules, inflammatory cytokines and chemokines. An excessive activation of inflammatory genes promotes enhanced adhesion of monocytes to the vascular endothelium, which is one of the first events in the development of atherosclerosis. The rate of inflammatory gene expression might be modulated by a variety of biologically active substances including lipid molecules derived by the action of the serum lipases on lipoproteins. A likely candidate capable of modulating inflammatory gene expression is endothelial lipase (EL). EL by hydrolyzing its preferential substrate HDL-phosphatidylcholine (HDL-PC) generates bioactive molecules, free fatty acids (FFAs) and saturated and unsaturated lysophosphatidylcholine (lyso-PC) species. Preliminary results have shown that the complex mixture of bioactive lipids generated by the action of EL on HDL led to upregulation of inflammatory genes including VCAM-1, IL-6, E-selektin, RANTES, COX-2, and cPLA2 in primary cultures of human endothelial cells (HAEC, HPAEC). 

The topics of the current project are:

1. Inflammatory activity of unsaturated lyso-PC species.
2. Signaling pathways and transcriptional factors triggered by unsaturated lyso-PCs.
3. The impact of unsaturated lyso-PCs on monocyte recruitment by vascular endothelium.
4. The impact of unsaturated lyso-PCs on vascular reactivity.  

2. Expression of endothelial lipase and other inflammatory molecules in human atherosclerotic plaques

The goal of this study is to assess expression levels of EL (and other inflammatory molecules: CRP, VCAM-1, E-selektin, ICAM-1, MCP-1, HO-1, CXCL16, COX-2 ) in human carotid atherosclerotic plaques and to examine the correlation between expression levels of EL (and other inflammatory molecules) and: i) plasma concentrations of inflammatory markers ii) lipid and lipoprotein plasma concentrations iii) lipid lowering, anti-inflammatory and blood-pressure medication.   

Experiments will comprise qRT-PCR analysis of EL (and additional inflammatory molecules) mRNA expression in carotid endarterectomy (ECA) specimens, as well as immunohistochemistry to determine semiquantitatively expression levels and distribution of   EL-protein (and additional inflammatory molecules)  in plaque associated cells.

3. Regulation of vascular tone, vascular reactivity and platelet aggregation by endothelial lipase (EL)-generated lipids

EL cleavage of HDL yields a complex mixture of bioactive lipids, which besides being capable of modulating expression of inflammatory molecules very efficiently modulate expression of prostaglandins (PG) in vascular endothelial cells. Because activity of COX enzymes and arachidonic acid supply are limiting factors for PG synthesis and because PGs modulate vascular reactivity and platelet homeostasis this project aims at elucidating the impact of EL-generated lipids on:

1. COX-1 and COX-2 expression and activity
2. Phospholipase A2 activity
3. Cellular phospholipids composition and cellular arachidonic acid balance
4. Signaling mechanisms responsible for the increased PG synthesis
5. Vascular reactivity
6. Platelet aggregation

4. Impact of omega-3 fatty acids on proliferation of vascular smooth muscle cells and vascular remodeling under normoxic and hypoxic conditions

Increased proliferation of vascular smooth muscle cells in pulmonary arteries leading to pathologic thickening of the vessel wall, lumen narrowing, increased resistance and blood pressure and eventually, if not treated right heart failure and death is a hallmark of pulmonary artery hypertension (PAH). Based on established numerous positive effects of omega-3 fatty acids on the vasculature, we have initiated studies in collaboration with the Olschewski laboratory (ZMF) to examine:

1. The capacity of omega-3 fatty acids to attenuate proliferation of primary pulmonary artery smooth muscle cells under hypoxia and normoxia.
2. Molecular and cellular mechanisms of omega-3 action on smooth muscle cells.
3. The impact of fish oil, which is enriched in omega-3 fatty acids, on hypoxia induced vascular remodeling and right heart enlargement in mice and rats.

Methods and know-how

• Generation and application of  recombinant adenovirus
• Basic molecular biology: Cloning, RT-PCR, qRT-PCR, Trasfections
• Cell culture: Cell lines, Stably transfected cells, Primary cell culture
• Experiments in mice: i.v. injection, perfusion, genotyping, blood collection
• ELISA assays
• Proliferation assays
• Vascular reactivity