Advertisement

Critical Care

, 17:P78 | Cite as

Endotoxin induces conversion of endothelial cells into activated fibroblasts

  • César Echeverría
  • Ignacio Montorfano
  • Daniela Sarmiento
  • Alvaro Becerra
  • Claudio Cabello-Verrugio
  • Felipe Simon
Poster presentation
  • 776 Downloads

Keywords

Activin Platelet Endothelial Cell Adhesion Tumor Growth Factor Vascular Endothelial Cadherin Maladaptive Process 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Background

Endothelial dysfunction is a key step in endotoxemia-derived sepsis syndrome pathogenesis. It is well accepted that the bacterial endotoxin lipopolysaccharide (LPS) induces endothelial cell (EC) dysfunction through immune system overactivation [1, 2, 3]. However, LPS can also affect ECs in the absence of participation by immune cells [4, 5, 6]. Although interactions between LPS and ECs evoke endothelial death, a significant portion of ECs are resistant to LPS challenge [6, 7, 8]. However, the mechanism that confers endothelial resistance to LPS is not known. Considering that LPS-resistant ECs exhibit a fibroblast-like morphology, suggesting that these ECs enter in a fibrotic program in response to LPS, our aim was to investigate whether LPS induces endothelial fibrosis and explore the underlying mechanism.

Materials and methods

We used two different models: primary ECs, and intact blood vessels (IBV). Both preparations were freshly obtained from umbilical cord veins from normal pregnancies, after patients' informed consent. The investigation conforms with the principles outlined in the Declaration of Helsinki. The Commission of Bioethics and Biosafety of Universidad Andres Bello approved all experimental protocols. Once the preparation was established they were cultured with or without LPS as a model of endotoxemia. ECs were exposed to 20 mg/ml LPS for 72 hours, while IBV was challenged to 20 mg/ml LPS on the inside for 48 hours.

Results

ECs exposed to LPS showed a fibroblast-like morphologic change. In addition, LPS-treated ECs showed an upregulation of both fibroblast-specific protein expression such as fibroblast specific protein-1 and α-smooth muscle actin, and extracellular matrix proteins secretion including fibronectin and collagen type III. In concordance, ECs exposed to endotoxin showed a severe downregulation of endothelial markers such as vascular endothelial cadherin and the platelet endothelial cell adhesion molecule-1 (CD31). Similar results were obtained in the endothelial monolayer from IBV perfused with LPS in which abundant fibrosis was observed. Furthermore, we demonstrate that LPS-induced EC fibrosis is dependent on the endotoxin receptor toll-like receptor-4. In addition, the participation of NAD(P)H oxidase activity and ROS generation was demonstrated using specific blockers. Finally, we demonstrated by means of small interfering technology and a pharmacological inhibitor that LPS-induced EC fibrosis is dependent on the activin like kinase-5 kinase activity, suggesting that tumor growth factor beta is involved in this fibrotic process.

Conclusions

We conclude that LPS is able and sufficient to promote endothelial fibrosis. It is noteworthy that LPS-induced endothelial fibrosis perpetuates endothelial dysfunction as a maladaptive process rather than a survival mechanism for protection against LPS. These findings are useful in improving current treatment against endotoxemia-derived sepsis syndrome and other inflammatory diseases.

Notes

Acknowledgements

Fondecyt 1121078 (FS), 1120380 (CCV), MECESUP UAB0802 (CE), UNAB DI-67-12/I (CE), and Millennium Institute on Immunology and Immunotherapy P09-016-F (FS).

References

  1. 1.
    Bone RC, Grodzin CJ, Balk RA: Sepsis: a new hypothesis for pathogenesis of the disease process. Chest 1997, 112: 235-243. 10.1378/chest.112.1.235CrossRefPubMedGoogle Scholar
  2. 2.
    Cohen J: The immunopathogenesis of sepsis. Nature 2002, 420: 885-891. 10.1038/nature01326CrossRefPubMedGoogle Scholar
  3. 3.
    Hotchkiss RS, Karl IE: The pathophysiology and treatment of sepsis. N Engl J Med 2003, 348: 138-150. 10.1056/NEJMra021333CrossRefPubMedGoogle Scholar
  4. 4.
    Dimmeler S, Brinkmann S, Neugebauer E: Endotoxin-induced changes of endothelial cell viability and permeability: protective effect of a 21-aminosteroid. Eur J Pharmacol 1995, 287: 257-261. 10.1016/0014-2999(95)00499-8CrossRefPubMedGoogle Scholar
  5. 5.
    Haendeler J, Zeiher AM, Dimmeler S: Vitamin C and E prevent lipopolysaccharide-induced apoptosis in human endothelial cells by modulation of Bcl-2 and Bax. Eur J Pharmacol 1996, 317: 407-411. 10.1016/S0014-2999(96)00759-5CrossRefPubMedGoogle Scholar
  6. 6.
    Simon F, Fernandez R: Early lipopolysaccharide-induced reactive oxygen species production evokes necrotic cell death in human umbilical vein endothelial cells. J Hypertens 2009, 27: 1202-1216. 10.1097/HJH.0b013e328329e31cCrossRefPubMedGoogle Scholar
  7. 7.
    Echeverria C, Montorfano I, Sarmiento D, Becerra A, Nunez-Villena F, Figueroa XF, Cabello-Verrugio C, Elorza AA, Riedel C, Simon F: Lipopolysaccharide induces a fibrotic-like phenotype in endothelial cells. J Cell Mol Med 2013, 17: 800-814. 10.1111/jcmm.12066PubMedCentralCrossRefPubMedGoogle Scholar
  8. 8.
    Becerra A, Echeverria C, Varela D, Sarmiento D, Armisen R, Montecino M, Simon F: Transient receptor potential melastatin 4 inhibition prevents lipopolysaccharide-induced endothelial cell death. Cardiovasc Res 2011, 91: 677-684. 10.1093/cvr/cvr135CrossRefPubMedGoogle Scholar

Copyright information

© Echeverría et al.; licensee BioMed Central Ltd. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors and Affiliations

  • César Echeverría
    • 1
  • Ignacio Montorfano
    • 1
  • Daniela Sarmiento
    • 1
  • Alvaro Becerra
    • 1
  • Claudio Cabello-Verrugio
    • 1
  • Felipe Simon
    • 1
    • 2
  1. 1.Facultad de Ciencias BiológicasUniversidad Andres BelloSantiagoChile
  2. 2.Millennium Institute on Immunology and ImmunotherapySantiagoChile

Personalised recommendations