Background: Apoptosis and inflammation are important features of endothelial dysfunction in diabetes. NF-κB plays a key role in inflammation and apoptosis through its ability to induce transcription of pro-inflammatory genes. In this study, we investigated the effect of β-adrenergic receptor stimulation on NF-κB and IκBα mediated apoptosis, inflammatory cytokines and adhesion molecules in hyperglycaemic HUVECs.
Methods: Human umbilical vein endothelial cells (HUVECs) were cultured in high (25 mM) and low (5 mM) concentrations of glucose. Cells were treated with 5, 10 and 20 µM isoproterenol and propranolol for 6, 12 and 24 hours. The experimental procedures consisted of Flow Cytometry, Western Blotting, ELISA, LDH release, DCFH-DA and TUNEL assays.
Results: Beta-adrenergic receptors stimulation by isoproterenol significantly reduced the levels of TNF-α, IL-1b, IL-6 and IL-8. TNF-α induced expression of ICAM-1, VCAM-1 and E-selectin were significantly reduced when treated with beta-ARs agonist. Significant dephosphorylation was observed at Ser-536 of NF-κB and Ser-32 and Ser-36 of IκBα in beta-ARs agonists treated HUVECs. Isoproterenol also significantly reduced apoptosis and ROS generation. No effect was observed on cell cycle arrest and Tyr-42 phosphorylation of IκBα upon isoproterenol treatment. The effect of isoproterenol was reversed by the antagonist propranolol.
Conclusion: Our data demonstrate that beta adrenergic receptors stimulation has protective effect on HUVECs. Stimulation of β-adrenergic receptor induces these changes via NF-κβ and IκBα.