The effect of interleukin-35 on the integrity, ICAM-1 expression and apoptosis of human aortic smooth muscle cells.

Background: Interleukin-35 (IL-35) is a novel immunomodulatory cytokine produced by CD4+ 25+ foxp3+ regulatory T-cells (T regs). Vascular smooth muscle cells (VSMCs) are involved in local immune homeostasis and certain chronic inflammatory pathologies. The effect of IL-35 on electrical impedance reflecting tissue integrity, the surface expression of ICAM-1 and mRNA expression of IL-32, as well as apoptosis in human primary aortic smooth muscle cells (Ao-SMCs) was investigated.

Methods: The influence of IL-35 on Ao-SMC integrity was assessed with the real-time cell electric impedance sensing system (RTCA-DP) based on normalized Cell Index (nCI). Additionally, Ao-SMCs were stimulated with IL-35 in order to assess ICAM-1 surface expression and apoptosis in flow cytometer. IL-32 mRNA expression was measured using real-time PCR.

Results: We found that the nCI of Ao-SMCs induced with IL-35 was lower after 12, 24 and 48h of incubation than the nCI of unstimulated cells. IL-35 slightly enhanced ICAM-1 surface expression and increased IL-32 mRNA expression in Ao-SMCs after 24h of induction. However, IL-35 did not affect Ao-SMC apoptosis, necrosis or viability.

Conclusion: Our data suggest that IL-35 may be an agent affecting the inflammatory properties of AoSMCs and thus it may regulate immune homeostasis of the vascular wall. Hence, IL-35 may be a novel player affecting Ao-SMC-controlled arterial wall immune homeostasis.