# Activator protein-1 (AP-1) inhibition prevents endothelial to mesenchymal transition in diabetes-associated atherosclerosis: a translational study

## TL;DR

This study shows that inhibiting AP-1 with T-5224 prevents EndMT and reduces atherosclerosis in diabetes, using both human and mouse models.

## Contribution

The study demonstrates the translational potential of AP-1 inhibition in diabetes-related atherosclerosis through human serum and preclinical models.

## Key findings

- T-5224 inhibited EndMT in human aortic endothelial cells exposed to diabetic serum.
- AP-1 inhibition reduced atherosclerosis in a mouse model of diabetes.
- T-5224 restored 77 out of 242 differentially expressed genes linked to EndMT under high glucose.

## Abstract

Endothelial to mesenchymal transition (EndMT), the transformation of endothelial cells into a mesenchymal-like state, is regulated by various factors, including transcription factors such as activator protein 1 (AP-1). While recent studies have confirmed the role of EndMT in atherosclerosis, the involvement of AP-1 in EndMT, particularly in the context of human diabetes, remains unclear.

This study aimed to elucidate the role of the AP-1 transcription factor complex in EndMT associated with atherosclerosis in diabetes, utilising both an in vivo preclinical model and an ex vivo model using patient-derived serum for translational relevance. Additionally, it sought to profile gene expression changes following AP-1 inhibition in an EndMT model under high glucose conditions.

Serum from patients with and without type 2 diabetes mellitus (T2DM) was used to assess EndMT in primary human aortic endothelial cells (HAECs) in the presence and absence of the AP-1 inhibitor T-5224. EndMT was evaluated through immunofluorescent staining of these cells and of aortic sections from a murine model of diabetes-associated atherosclerosis in a preclinical early intervention study. Furthermore, HAECs were used to explore the effects of AP-1 inhibition on the transcriptional signature of EndMT.

Patient-derived serum induced EndMT in HAECs, which T-5224 effectively prevented, as confirmed by immunofluorescent staining. Immunofluorescent analysis of the aortic sinus also revealed that T-5224 treatment inhibited EndMT, leading to reduced atherosclerosis in Apoe−/− mice. In parallel, in the HAECs-based in vitro EndMT model, T-5224 mitigated TNF-α and high glucose-induced EndMT. RNA sequencing identified 242 differentially expressed genes (DEGs) associated with EndMT under high glucose conditions, with T-5224 treatment restoring the expression of 77 DEGs.

This study identifies AP-1 inhibition with T-5224 as a potential therapeutic approach for EndMT resulting in reduced atherosclerosis in diabetes. The use of human serum underscores the translational relevance of these findings.

The online version contains supplementary material available at 10.1186/s12933-025-03060-5.