Human C-peptide antagonises high glucose-induced endothelial dysfunction through the nuclear factor-κB pathway

P. Luppi, V. Cifarelli, H. Tse, J. Piganelli, M. Trucco

Research output: Contribution to journalArticlepeer-review

68 Scopus citations

Abstract

Aims/hypothesis: Endothelial dysfunction in diabetes is predominantly caused by hyperglycaemia leading to vascular complications through overproduction of oxidative stress and activation of the transcription factor nuclear factor-κB (NF-κB). Many studies have suggested that decreased circulating levels of C-peptide may play a role in diabetic vascular dysfunction. To date, the possible effects of C-peptide on endothelial cells and intracellular signalling pathways are largely unknown. We therefore investigated the effect of C-peptide on several biochemical markers of endothelial dysfunction in vitro. To gain insights into potential intracellular signalling pathways affected by C-peptide, we tested NF-κB activation, since it is known that inflammation, secondary to oxidative stress, is a key component of vascular complications and NF-κB is a redox-dependent transcription factor. Methods: Human aortic endothelial cells (HAEC) were exposed to 25 mmol/l glucose in the presence of C-peptide (0.5 nmol/l) for 24 h and tested for expression of the gene encoding vascular cell adhesion molecule-1 (VCAM-1) by RT-PCR and flow cytometry. Secretion of IL-8 and monocyte chemoattractant protein-1 (MCP-1) was measured by ELISA. NF-κB activation was analysed by immunoblotting and ELISA. Results: Physiological concentrations of C-peptide affect high glucose-induced endothelial dysfunction by: (1) decreasing VCAM-1 expression and U-937 cell adherence to HAEC; (2) reducing secretion of IL-8 and MCP-1; and (3) suppressing NF-κB activation. Conclusions/interpretation: During hyperglycaemia, C-peptide directly affects VCAM-1 expression and both MCP-1 and IL-8 HAEC secretion by reducing NF-κB activation. These effects suggest a physiological anti-inflammatory (and potentially anti-atherogenic) activity of C-peptide on endothelial cells.

Original languageEnglish
Pages (from-to)1534-1543
Number of pages10
JournalDiabetologia
Volume51
Issue number8
DOIs
StatePublished - Aug 2008

Keywords

  • Atherosclerosis
  • C-peptide
  • Cytokines
  • Endothelial cells
  • Inflammation
  • Monocytes
  • NF-κB
  • Nuclear factor κB
  • Vascular smooth muscle cells

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