Low extracellular Ca2+: a mediator of endothelial inflammation

Nephrol Dial Transplant. 2009 Nov;24(11):3306-12. doi: 10.1093/ndt/gfp354. Epub 2009 Jul 18.

Abstract

Background: Recent studies have suggested that vitamin D and an imbalance in calcium homeostasis may have an impact on the cardiovascular system. The aim of this study was to assess the impact of different concentrations of extracellular Ca(2+) on human umbilical vein cord endothelial cells (HUVEC) by measuring its effect on parameters involved in the pathogenesis of vascular inflammatory responses.

Methods: HUVEC were grown in the 3.5, 4.5 or 5.8 mg/dL concentration of extracellular Ca(2+) for 2-3 weeks. Expression of adhesion molecules was analysed by flow cytometry. Endothelial nitric oxide synthase (eNOS), receptor of advanced glycation end-product (RAGE) and interleukin-6 (IL-6) mRNA expressions were determined by real-time PCR. eNOS, inhibitor kappa Balpha (IkappaBalpha) and phosphorylated IkappaBalpha protein levels by Western blot, eNOS activity by conversion of [(14)C]-arginine to [(14)C]-citrulline, IL-6 and osteoprotegerin (OPG) secretion by ELISA and DNA-binding activity of nuclear factor kappa B (NFkappaB)-p65 were assayed colorimetrically in nuclear extracts.

Results: In the presence of low Ca(2+) (3.5 mg/dL), protein expressions and activity of eNOS were diminished, while the protein expressions of intercellular adhesion molecule-1 (ICAM-1), as well as the mRNA expressions of RAGE and IL-6, were elevated. The protein secretions of IL-6 and OPG were also stimulated in low Ca(2+) concentration. At this concentration, the DNA-binding activity of NFkappaB was enhanced, probably due to the decreased level of IkappaBalpha.

Conclusions: These results suggest that lower extracellular ionized Ca(2+) may play a relevant role in modifying endothelial cells functions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calcium / metabolism*
  • Cells, Cultured
  • Endothelial Cells / physiology*
  • Humans
  • Inflammation / etiology*
  • Intercellular Adhesion Molecule-1 / analysis
  • Interleukin-6 / genetics
  • NF-kappa B / physiology
  • Nitric Oxide Synthase Type III / metabolism
  • Osteoprotegerin / biosynthesis
  • RNA, Messenger / analysis
  • Receptor for Advanced Glycation End Products
  • Receptors, Immunologic / genetics

Substances

  • Interleukin-6
  • NF-kappa B
  • Osteoprotegerin
  • RNA, Messenger
  • Receptor for Advanced Glycation End Products
  • Receptors, Immunologic
  • Intercellular Adhesion Molecule-1
  • NOS3 protein, human
  • Nitric Oxide Synthase Type III
  • Calcium