Abstract 12466: Suppression of Inflammatory Activity in Vascular Endothelial Cells Reduces EndMT in Response to Oscillatory Shear Stress

Abstract

Background: The incidence of pro-atherogenic lesions is greater in the branching regions of artery compared to non-branching regions. Disturbed blood flow in the atheroprone regions exerts oscillatory shear stress (OSS) to the vascular wall, particularly endothelial cells (ECs), and OSS is a risk factor for the development of pro-atherogenic lesions. This study aims to assess the impact of OSS on phenotypic transition in artery ECs. Methods and Results: Immunofluorescence staining and image quantification revealed that inflammatory activity and endothelial-to-mesenchymal transition (EndMT) are greater in mouse aortic arch than in the descending thoracic aorta. Inflammatory biomarker ICAM-1 is colocalized with the EndMT biomarker, vimentin and α-smooth muscle actin, in ECs of the aorta arch. As cells in aortic arch sustain OSS, we tested the hypothesis that OSS induces EndMT in artery ECs by a pro-inflammatory mechanism, using a three-dimensional microengineered human artery-on-a-chip system. Human coronary artery ECs were cultured on the surface of a collagen I-coated membrane and subjected to OSS. Single-cell RNA sequencing analysis revealed that inflammatory and EndMT-related genes were enriched in ECs after being exposed to OSS for 24 h. OSS-induced inflammatory response and EndMT were confirmed by immunoblotting and immunofluorescence staining. These changes were abolished by inhibiting the p38 MAPK-NF-κB signaling pathway. Moreover, anti-inflammatory cytokine, IL-37, suppressed the inflammatory response and prevented EndMT in ECs exposed to OSS. Importantly, expression of IL-37 in mice markedly reduced the level of inflammatory biomarker and the density of cells displaying EndMT biomarkers in the endothelium of aortic arch. Conclusion: OSS induces EndMT in artery ECs through a pro-inflammatory mechanism involving the p38 MAPK-NF-κB signaling pathway and contributes to the pro-atherogenic microenvironment in regions sustaining disturbed blood flow. Anti-inflammatory cytokine IL-37 may have the therapeutic potential for suppressing endothelial phenotypic transition caused by disturbed blood flow.