Supervisors info:
Σανούδου Δέσποινα Επίκ. Καθηγ. Ιατρικής Σχολής Αθηνών (Επιβλέπουσα), Λιανίδου Εύη Καθηγ. ΕΚΠΑ, Γεωργόπουλος Σπύρος Ερευνητής Γ΄ΙΙΒΕΑΑ
Summary:
Αtherosclerosis, an inflammatory disease of the large arteries, is the primary
cause of heart disease and stroke. In westernized societies, atherosclerosis is
the underlying cause of about 50% of all deaths. However, no effective
treatment for atherosclerosis is available. Damage of endothelial monolayer
integrity is an important initiating event in the pathogenesis of
atherosclerosis which can be promoted by endothelial cell (EC) apoptosis. On
the contrary, it can be reduced by re-endothelialization. Αpolipoprotein E
(ApoE) protects from atherosclerosis through the clearance of triglyceride-rich
lipoproteins and formation of apoE-containing HDL particles (HDL-apoE), in
vivo. Ηowever, the physiological functions of HDL-apoE that affect endothelium
and may be relevant to atheroprotection have not yet been studied. The aim of
our study was the molecular analysis of the potential atheroprotective role of
discoidal reconstituted HDL particles containing human wild type apoE3 and
phospholipids (rHDL-apoE3). Using whole genome Affymetrix oligonucleotide
microarrays (GeneChip Human Gene 1.0 ST Array, 28.869 genes), the molecular
effect of the rHDL-apoE3 treatment on HAECs (Normal Human Aortic Endothelial
Cells) was studied. Multilevel bioinformatical analysis using 2-fold and 0.05
false discovery rate thresholds identified 198 significantly changed genes (89
upregulated, 109 downregulated) involved in a broad range of different
molecular pathways. Particularly, rHDL-apoE3 induced significant changes in the
expression of 27 EC migration-related genes that can be classified in the
following pathways: 1) The ERK1/2 pathway that when activated could promote EC
migration through cytoskeletal reorganization and extracellular matrix
degradation, 2) the P38 MAPK/PAK/ROCK pathways downstream of RHO GTPases whose
activation potentially lead to actin polymerization and cytoskeletal
rearrangement, 3) the PI3K/AKT/eNOS (endothelial Nitric Oxide Synthase) pathway
whose activation is expected to affect the release of nitric oxide (NO), which,
in turn, induces cell migration via different molecular mechanisms, and
finally, 4) the signaling pathway of integrins at focal adhesions that could
lead to activation of FAK, PI3K, ΕRK1/2, PAK and ROCK. These findings suggest
that rHDL-apoE3 could induce EC migration via cytoskeletal reorganization and
NO production. Paralleling the above findings, significant changes were
observed in 64 apoptosis-related genes in response to rHDL-apoE3 treatment that
can be classified in the following pro- or apoptotic or survival pathways: 1)
The PI3K/AKT survival pathway, 2) the NFκΒ anti-apoptotic pathway, 3) the
cytochrome C (cyto-C)-mediated mitochondrial apoptotic pathway, 4) the death
receptor-triggered apoptotic pathway, 5) the P53-dependent apoptotic pathway,
and finally, 6) the P38 and/or JNK-mediated apoptotic pathway. The overall
observations point to a potential activation of survival pathways (the PI3K/AKT
pathway and the NFκΒ anti-apoptotic pathway) and inactivation of pro-apoptotic
pathways (the cytoC- and P53-mediated pathway and the death receptor-triggered
apoptotic pathway) in response to rHDL-apoE3 treatment. Overall, the evidence
emerging from this study suggests, for the first time, that rHDL-apoE3
treatment induces alterations at the transcriptional level in molecular
mechanisms related to EC migration and apoptosis, two key functions of
controlling endothelium integrity. Through these changes rHDL-E3 could protect
from atherosclerosis contributing to the maintenance of intimal layer
integrity. A deeper understanding of the effect of rHDL-apoE3 on the
endothelium at the cellular/molecular level promises to facilitate the
development of new therapies to prevent from or treat atherosclerosis.
Keywords:
Atherosclerosis , HDL containing apolipoprotein E3, Microarrays , Migration, Apoptosis
