Clozapine impairs angiogenic function and cellular bioenergetics in primary human endothelial progenitor cells and zebrafish: involvement of aryl hydrocarbon receptor signaling.

Clozapine is indispensable for treatment-resistant schizophrenia, but its effects on endothelial repair and their potential relevance to coronary artery disease remain insufficiently characterized. We combined a propensity score-matched nationwide cohort of 28,802 patients with experiments in primary human endothelial progenitor cells and Tg(fli1:EGFP) zebrafish embryos. Clozapine use was associated with a higher incidence of coronary artery disease during up to 12 years of follow-up (adjusted hazard ratio 1.24, 95% confidence interval 1.13-1.36). In primary human endothelial progenitor cells, clozapine was tested at 1-30 μM for 24-48 h. It concentration-dependently reduced cell growth, migration, tube formation, oxygen consumption, and extracellular acidification. In silico docking predicted a potential interaction with the aryl hydrocarbon receptor (AHR) ligand-binding pocket. Clozapine increased CYP1A1 mRNA expression and reduced AHR protein level. The AHR antagonist CH-223191 (10 μM) partially restored cell growth and shifted extracellular acidification toward control levels, supporting involvement of AHR signaling. Clozapine also increased autophagosome accumulation and LC3-II abundance, while 3-methyladenine intensified growth inhibition, consistent with a potentially compensatory autophagy-associated response. Tg(fli1:EGFP) zebrafish embryos exposed to clozapine (15 or 30 μM) during 12-30 or 30-72 h post-fertilization developed concentration-dependent vascular abnormalities and increased mortality. These findings identify AHR-associated metabolic and angiogenic dysfunction as a plausible vascular effect of clozapine, while further studies are required to determine its contribution to the clinical association and its relevance to chronic therapeutic exposure.