Galectin7 attenuates abdominal aortic aneurysm progression by resisting disturbed flow induced endothelial-to-mesenchymal transition

<b>Background:</b> The switch to endothelial-to-mesenchymal transition (EndMT) in endothelial cells (ECs) induced by disturbed flow (d-flow) has been identified as the critical driver of the pathogenesis of inflammatory vascular disorders. We aimed to investigate the role of EndMT in abdominal aortic aneurysms (AAA) and the underlying mechanism. <b>Methods:</b> Immunoblotting, immunofluorescence and transmission electron microscope were used to assess d-flow-induced EndMT in human and mouse AAA models (Ang II/PPE). An Ibidi pump system was used to produce d-flow on human aortic endothelial cells (HAECs), and the expression of galectin-7 was enhanced and weakened using an adeno-associated virus. Furthermore, single-cell RNA sequencing was performed to explore the underlying mechanism of galectin-7-mediated EndMT. <b>Results:</b> EndMT induced by d-flow, which suppressed galectin-7 expression, was positively correlated with AAA. Enhanced galectin-7 expression inhibited d-flow-induced EndMT and AAA progression, whereas reduced galectin-7 expression resulted in the opposite effect. Mechanistically, we found a EndMT-related cluster in HAECs by single-cell RNA sequencing, and the SRGN gene in this cluster was considered the core gene. Galectin-7 bound competitively to the transcription factor CREB, resulting in the inhibition of SRGN transcription, which in turn prevented TGFβ/smad pathway activation, thereby restoring EndMT progression. <b>Conclusions:</b> EndMT transformation in ECs exposed to d-flow was the critical driver of AAA development. Furthermore, endothelium-enriched galectin-7 suppressed the EndMT process induced by d-flow and prevent AAA progression by transcriptionally inhibiting SRGN via competitive binding with CREB to restrict TGFβ/smad pathway.