Dexamethasone modulate TWIST mediated EndMT changes in venous EC under acute shear stress. Implications for vein grafts disease.

BackgroundThe use of vein grafts in coronary artery surgery is complicated by a high late restenosis rate resulting from the development of intimal hyperplasia, and accelerated atherosclerosis. TGF{beta} has been implicated in the process of intimal hyperplasia but the role of TGF{beta} driven Endothelial to mesenchymal is not fully understood. Here, we have investigated the hypothesis that arterial shear stress (flow) can trigger Endothelial to mesenchymal changes in venous ECs mediated by TGF{beta} / SMAD pathway in-vitro and ex-vivo and that a brief pretreatment of vein with Dexamethasone can suppress such changes. Methods and ResultsComparative reverse-transcriptase polymerase chain reaction, immunostaining and Western blotting revealed that arterial shear stress induced TGF{beta} / SMAD dependent in HUVEC which was regulated by TWIST 1&2 as the selective inhibition of TWIST 1 or 2 using specific siRNA suppressed EndMT in response to shear stress. We also noted that brief pretreatment of HUVECs with Dexamethasone can modulate EndMT changes in response to shear stress. Using spatial cell sequencing in human long saphenous vein segments exposed to acute arterial flow identified a cluster of cells that had both EC and SMC phenotypes where TWIST2 was significantly upregulated. We validated the untargeted spatial findings in segments of veins under acute arterial flow ex-vivo using comparative reverse-transcriptase polymerase chain reaction, immunostaining and RNAscope and observed that Dexamethasone can suppress EndMT changes in vein segments by suppressing TGF{beta} / SMAD/ TWIST1 &2. ConclusionDexamethasone brief pretreatment can suppress EndMT changes triggered by acute exposure of long saphenous vein segments to arterial haemodynamics by modulating TGF{beta} / SMAD / TWIST1 &2 pathway.