Eicosapentaenoic acid inhibits endothelial cell migration in vitro
Journal of Angiogenesis Research. 2010;
Received: 1 April 2010 | Accepted: 9 July 2010 | Published: 9 July 2010
Vascular Cell ISSN: 2045-824X
Abstract
Background
As
Methods
To this purpose, using functional and morphological
Results
We report here that incubation of endothelial cells with
Conclusions
Given the importance of endothelial cell migration in the repair of vascular injuries, these
Background
Dietary intake of
In this study, we focused on the effect of
Furthermore,
Here, we surmised that, in addition to these responses, PUFA might interfere with other biological processes that involve membrane proteins, such as cell migration.
Results
Addition of n-3 PUFA increases the membrane content of EPA and DHA
Incubation of confluent EC (for 24 hours at 37°C) with a mixture of
Figure 1
n-3 PUFA inhibit endothelial cell migration
We next examined the effect of
Figure 2
EPA is responsible for the n-3 PUFA effect on cell migration
The mixture of
Table 1
Medium | 852 ± 15 |
Vehicle (ethanol) | 905 ± 118 |
PUFA EE | 1166 ± 94 ** |
DHA EE | 896 ± 51 |
EPA EE | 1189 ± 60 ** |
DHA EE + EPA EE | 1156 ± 9 ** |
As above, at 24 hours, the wound width was reduced in control- and vehicle (ethanol)-treated cells, but not in cells treated with the mixture of
n-3 PUFA-dependent inhibition of migration is MAPK-independent
Mitogen-Activated Protein Kinases (MAPK) are key regulators of cell migration [12]. In particular, EC migration into a wound requires ERK-1/2 activation [13]. In agreement with these findings, we observed that migration was reduced in cells treated with the ERK-1/2 inhibitor PD098059, compared with control-treated cells (Fig. 3a). However, when analyzing cells that had been treated in either the presence or absence of the
Figure 3
In addition, we found that the p38/SAPK2 activator anisomycin induced dose-dependent (2-2,000 nM) inhibition of migration, with half-maximal inhibition at about 250 nM (Fig. 3c). However, non-inhibitory concentrations of
n-3 PUFA-dependent inhibition of migration is associated with cytoskeletal changes
Fluorescence microscopy revealed morphological differences in the migrating cells that were facing the wound (Fig. 4a). Specifically, in control-and vehicle-treated cells, vinculin-containing focal adhesions (FA) distributed evenly at the base of the leading lamella, while actin filaments aligned in parallel to the wound. In contrast, in
Figure 4
Similar cytoskeletal changes were detectable in the confluent cells that were not facing the wound (not shown) and in non-contacting cells (Fig. 4b). Specifically, in non-contacting cells incubated with medium or vehicle, FA evenly distributed throughout the cell, while actin filaments organized in cortical fibers. In contrast, upon treatment with
We also determined that the fraction of non-contacting cells with peripheral FA was negligible in control- and vehicle-treated cells (0.0 ± 0.0 and 0.7 ± 1.2%, respectively), but high (70.0 ± 10.6%) in cells treated with the mixture of
Discussion
The major findings of this study are that
The anti-migratory effect of EPA was not expression of a nonspecific anti-motility action. Actually, using the modified Boyden chamber assay, previous studies reported that EPA (but not DHA) increased EC migration [14] and rescued the anti-migratory action of cholesterol [15]. These studies are not at odds with the herein reported inhibitory action of EPA, as the Boyden assay analyzes the individual migration of single cells, while the wound assay evaluates the collective migration of cohesive cell sheets. In addition, our findings mirror the observation that EPA (but not DHA) inhibited the ability of EC to form tube-like structures in collagen gels, which requires coordinated motility and cytoskeletal rearrangements of cohesive EC [16].
Published evidence prompted us to evaluate the possible involvement of the MAPK. In particular, hydrogen peroxide-dependent distribution of the FA to the cell periphery [17] (similar to the one induced by
Most of our experiments relied on the use of a mixture of
However, we also used purified
Other studies have shown differences in the biological effects of EPA and DHA [25]. In addition to differences in metabolic and hemodynamic effects (
Clearly,
Finally, besides migration, one should take into account other effects of the
Conclusions
In conclusion, we have reported here that
Methods
Cell lines, antibodies and reagents
The endothelial cell line H5V, which was derived from the murine heart [37], was cultured in D-MEM (Gibco-BRL) supplemented with 10% fetal bovine serum (Sigma). Mouse anti-vinculin mAb hVIN-1, mouse anti-alpha-tubulin mAb B-5-1-2 and FITC-phalloidin were from Sigma. TRITC-labeled anti-IgG (H+L) anti-mouse antibody was from Jackson Immuno Research Laboratories Inc. The mixture of
Fatty acid analysis
Membrane isolation and analysis of their relative fatty acid composition were performed as described [38]. Briefly, lipids from approximately 2.5 × 105 EC were extracted according to the method of Folch [39]. Then, aliquots of the chloroform phases containing lipids were evaporated to dryness. Fatty acid methyl esters in total lipids were prepared and injected into an Autosystem XL gas chromatograph (Perkin Elmer) connected with a flame ionisation detector. Individual fatty acid methyl esters were identified by comparing their retention times with corresponding standards (run in parallel), and their composition was calculated using a Turbochrom system, version 6.1 (Perkin Elmer).
Wound assay
Cells were seeded (at a density of 1.5 × 105/cm2) onto glass cover slips (that had been coated with fibronectin; 7 μg/mL) and grown to confluence. Then, the culture medium was removed, and scratch wounds were produced using a plastic tip for 1,000 μL pipettes. After two washes with D-PBS, cells were incubated with D-MEM medium containing 10% serum, in the presence of either medium alone, or the vehicle (ethanol) or
Immunofluorescence microscopy
For the analysis of non-contacting cells, cells were seeded onto fibronectin-coated glass cover slips, allowed to adhere for 120 minutes and then incubated with the indicated compound for additional 60 minutes. Cells were then treated as above and stained with primary and TRITC-labeled secondary antibodies, as described [41]. Cover slips were mounted in 488-Mowiol and analyzed with a Zeiss Axiophot microscope (equipped with 100X Plan-Neofluar Ph3 objective lens). A similar protocol was used for analyzing migrating cells at the wound edge.
Acknowledgements
This work was partially supported by Società Prodotti Antibiotici, Milano.
Authors’ original submitted files for images
Below are the links to the authors’ original submitted files for images.
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