Trimethylamine N-oxide promotes PERK-mediated endothelial-mesenchymal transition and apoptosis thereby aggravates atherosclerosis

TMAO affects cardiovascular function by promoting ROS production, inducing endoplasmic reticulum stress through the PERK-eIF2α pathway, and activating ATF3/ATF4 and CHOP-mediated apoptosis. It also activates TGF-β signaling, leading to SMAD3/SMAD4 phosphorylation and apoptosis in mesenchymal cells. These processes impact cardiac function, lipid levels, and tissue pathology, as evaluated by cardiac tests, lipid measurements, and histological staining. The eukaryotic translation initiation factor 2-alpha kinase 3 also known as protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK). • TMAO promotes the endothelial-mesenchymal transition. • Inhibiting PERK expression and activation can slow the progression of EndMT. • PERK mediates TMAO signalling to TGF-β1/2 via ATF3. The endothelial-mesenchymal transition (EndMT) is involved in the development of atherosclerosis (AS) and is a key process in vascular endothelial injury. Oxidative stress, inflammation, and apoptosis are common causes of EndMT, and EndMT progression can further accelerate the development of AS. The metabolite trimethylamine N-oxide (TMAO) is produced by the gut microbiome and is implicated in the development of several diseases, including diabetes and chronic kidney disease. However, the impact of TMAO on transforming growth factor β1(TGF-β1)-induced EndMT remains unclear. We hypothesize that TMAO exacerbates plaque formation and cardiac function impairment by promoting EndMT. Herein, we showed that high serum TMAO levels caused plaque formation, cardiac function damage and haemodynamic changes in ApoE −/− mice. In vitro, TMAO upregulated mesenchymal markers and downregulated endothelial markers in HAECs. Furthermore, TMAO increased the migratory capacity of EndMT cells. Mechanistically, we found that PERK downregulation could alleviate TMAO-induced oxidative stress, EndMT, plaque formation and cardiac function damage. Further study showed that activated transcription factor 3 (ATF3), the downstream molecule of protein kinase RNA-like endoplasmic reticulum kinase (PERK), could bind with TGF-β1/2 and affect EndMT. Overall, TMAO promotes EndMT, possibly through the PERK-eIF2α-ATF4-CHOP or the PERk-eIF2α-ATF3-TGF-β signalling pathways.