Knockdown of Transthyretin ameliorates ferroptosis in myocardial ischemia-reperfusion injury.

BACKGROUND: Myocardial ischemia/reperfusion (I/R) injury is a major cause of cardiac dysfunction, with ferroptosis playing a critical role. Transthyretin (TTR), a protein with neuroprotective and antioxidant properties, has been implicated in cardiovascular diseases. However, its specific role in myocardial I/R injury is unknown. This study explores the relationship between TTR and ferroptosis in myocardial I/R injury. METHODS AND RESULTS: The mice myocardial I/R models were established, after which transcriptomic RNA sequencing was performed to identify key genes. H9c2 cardiomyocytes underwent hypoxia/reoxygenation (H/R) treatment accompanied by siRNA-mediated knockdown of TTR. Cells were divided into control (Con), H/R, si-NC + H/R, and si-TTR + H/R groups. Ferroptosis markers were analyzed, including Fe²⁺ (colorimetric assay), ROS (flow cytometry), GSH, and lipid peroxidation (LPO). The levels of TFR1, SLC7A11, GPX4, and ACSL4 was measured by qRT-PCR and Western blot. Mitochondrial morphology was assessed via transmission electron microscopy. The Con group maintained normal cell viability, redox balance, and mitochondrial morphology. The H/R group exhibited ferroptosis-associated damage, including increased ROS, Fe²⁺, LPO, and TFR1/ACSL4 expression, along with decreased GSH, SLC7A11, and GPX4. TTR knockdown (si-TTR + H/R) mitigated these effects, restoring cellular homeostasis and improving mitochondrial integrity. CONCLUSIONS: TTR enhances ferroptosis during myocardial I/R injury. Its silencing protects cardiomyocytes by modulating iron metabolism, oxidative stress, and lipid peroxidation, making it a potential therapeutic target.