Interleukin 6 (IL-6) is a multifunctional cytokine that plays a central role in inflammation by controlling differentiation, proliferation, migration and apoptosis of targeted cells. In recent years it has been shown that IL-6 induces release of vascular endothelial growth factor, and thus might play an important role in angiogenesis.

Aim: The present study aimed at investigating the involvement of IL-6 in angiogenesis by studying migration and tube formation of vascular endothelial cells.

Methods: Migration and tube formation of human umbilical vein endothelial cells (HUVEC) were studied after treatment with IL-6, soluble IL-6 receptor or the combination of IL-6 and the soluble IL-6 receptor. Migration and tube formation was also studied in HUVEC after knock-down of IL-6 using siRNA. Knock down of IL-6 was confirmed using ELISA.

Results: Treatment with IL6 (50ng/ml), soluble IL-6 receptor (100 ng/ml) or the combination of IL6 and soluble IL6 receptor did not affect tube formation or migration. Knock down of IL-6, on the other hand, resulted in reduced tube formation (number of tubes and total tube length) as well as slightly reduced migration of HUVEC. This inhibition could be restored after addition of exogenous IL-6 (50ng/ml).

Conclusion: Our data suggests that IL-6 is involved in angiogenesis and that IL-6 produced by the endothelial cells themselves is enough in to maintain normal tube formation and migration. Targeting IL-6 may be a novel strategy to prevent undesired formation of new blood vessels.