C-peptide inhibits leukocyte-endothelium interaction in the microcirculation during acute endothelial dysfunction

Area of Science:

• Biochemistry
• Physiology
• Immunology

Background:

• C-peptide, a byproduct of insulin production, is known to induce nitric oxide (NO)-mediated vasodilation.
• Nitric oxide plays a crucial role in regulating leukocyte-endothelium interactions.

Purpose of the Study:

• To investigate the hypothesis that C-peptide inhibits leukocyte-endothelium interactions through enhanced endothelial NO release.
• To explore the specific mechanisms by which C-peptide affects these interactions.

Main Methods:

• Intravital microscopy was used to observe leukocyte-endothelium interactions in rat mesentery.
• Leukocyte interactions were measured after administration of C-peptide, thrombin, or L-NAME.
• Expression of cell adhesion molecules (P-selectin, ICAM-1) and endothelial nitric oxide synthase (eNOS) mRNA levels were analyzed.

Main Results:

• Thrombin or L-NAME significantly increased leukocyte rolling, adhesion, and transmigration.
• C-peptide administration attenuated these increases, significantly inhibiting leukocyte-endothelium interactions.
• A scrambled C-peptide sequence did not show inhibitory effects, indicating specificity.
• C-peptide decreased P-selectin and ICAM-1 expression and increased eNOS mRNA levels.
• Basal NO release from the aorta was markedly increased in C-peptide-treated rats.

Conclusions:

• C-peptide is a potent inhibitor of leukocyte-endothelium interactions.
• This inhibitory effect is mediated by the maintenance of NO release from the vascular endothelium.
• C-peptide specifically downregulates endothelial cell adhesion molecules, suggesting therapeutic potential.