Format

Send to

Choose Destination
PLoS One. 2014 Sep 19;9(9):e108254. doi: 10.1371/journal.pone.0108254. eCollection 2014.

Regulation of thrombomodulin expression and release in human aortic endothelial cells by cyclic strain.

Author information

1
School of Biotechnology, Dublin City University, Glasnevin, Dublin, Ireland.
2
School of Health & Human Performance, Dublin City University, Glasnevin, Dublin, Ireland; Centre for Preventive Medicine, Dublin City University, Glasnevin, Dublin, Ireland.
3
School of Biotechnology, Dublin City University, Glasnevin, Dublin, Ireland; Centre for Preventive Medicine, Dublin City University, Glasnevin, Dublin, Ireland.

Abstract

BACKGROUND AND OBJECTIVES:

Thrombomodulin (TM), an integral membrane glycoprotein expressed on the lumenal surface of vascular endothelial cells, promotes anti-coagulant and anti-inflammatory properties. Release of functional TM from the endothelium surface into plasma has also been reported. Much is still unknown however about how endothelial TM is regulated by physiologic hemodynamic forces (and particularly cyclic strain) intrinsic to endothelial-mediated vascular homeostasis.

METHODS:

This study employed human aortic endothelial cells (HAECs) to investigate the effects of equibiaxial cyclic strain (7.5%, 60 cycles/min, 24 hrs), and to a lesser extent, laminar shear stress (10 dynes/cm2, 24 hrs), on TM expression and release. Time-, dose- and frequency-dependency studies were performed.

RESULTS:

Our initial studies demonstrated that cyclic strain strongly downregulated TM expression in a p38- and receptor tyrosine kinase-dependent manner. This was in contrast to the upregulatory effect of shear stress. Moreover, both forces significantly upregulated TM release over a 48 hr period. With continuing focus on the cyclic strain-induced TM release, we noted both dose (0-7.5%) and frequency (0.5-2.0 Hz) dependency, with no attenuation of strain-induced TM release observed following inhibition of MAP kinases (p38, ERK-1/2), receptor tyrosine kinase, or eNOS. The concerted impact of cyclic strain and inflammatory mediators on TM release from HAECs was also investigated. In this respect, both TNFα (100 ng/ml) and ox-LDL (10-50 µg/ml) appeared to potentiate strain-induced TM release. Finally, inhibition of neither MMPs (GM6001) nor rhomboids (3,4-dichloroisocoumarin) had any effect on strain-induced TM release. However, significantly elevated levels (2.1 fold) of TM were observed in isolated microparticle fractions following 7.5% strain for 24 hrs.

CONCLUSIONS:

A preliminary in vitro investigation into the effects of cyclic strain on TM in HAECs is presented. Physiologic cyclic strain was observed to downregulate TM expression, whilst upregulating in a time-, dose- and frequency-dependent manner the release of TM.

PMID:
25238231
PMCID:
PMC4169621
DOI:
10.1371/journal.pone.0108254
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Public Library of Science Icon for PubMed Central
Loading ...
Support Center