Smad2 – a novel regulator of vascular inflammation

Background Endothelial cells (ECs) are an indispensable part of the vascular inflammatory response that leads to the development of cardiovascular disease such as atherosclerosis. Exposed to inflammatory stimuli, ECs express... [ view full abstract ]

Background
Endothelial cells (ECs) are an indispensable part of the vascular inflammatory response that leads to the development of cardiovascular disease such as atherosclerosis. Exposed to inflammatory stimuli, ECs express chemokines and adhesion molecules, which attract immune cells. ECs as the “gatekeepers” of vascular inflammation are a prime target for cardiovascular disease inhibition.
Methods
Microarray (Primeview) analysis was performed on human aortic endothelial cells (HAECs) transfected with Smad2 or Control siRNA exposed to physiological flow (10 dynes/cm2) in a parallel flow reactor for 20h or cultured statically. Differentially expressed genes were determined using R Bioconductor and validated with qPCR. String10 was used for network and GO analysis. qPCR and monocyte (THP-1) adhesion were performed after TNFα stimulation (150 U/ml for 4 hours).
Results/Conclusion
Smad2 knock-down affected 185 genes under flow and 35 genes in static culture. Immune response was within the most enriched GO terms. Inflammatory genes were downregulated in flow exposed cells upon Smad2 knock-down and subsequent TNFα stimulation did not lead to their induction while cells in static culture were still activated (131-fold increase for VCAM-1 and 53-fold for E-selectin). Monocyte adhesion (see Figure) supported this finding with a very low adhesion on Smad2 siRNA treated cells under flow (11.9 ± 9.1) compared high counts in static culture (143.9 ± 68.7). These results show a fundamental importance of Smad2 in the inflammatory response of ECs. Future work is focused on unraveling the underlying mechanism, which opens the door for the discovery of novel drug treatments in cardiovascular diseases.