Hydrogen sulfide mitigates iron-induced mitochondrial dysfunction in vascular smooth muscle cells

Mitochondrial dysfunction is a key contributor to cellular stress, impaired metabolism, and disease progression. Oxidative stress and iron overload further exacerbate mitochondrial impairment. While wild-type (WT) vascular smooth muscle cells (VSMCs) maintain redox balance under iron exposure, cystathionine γ-lyase knockout (CSE-KO) cells have impaired iron-regulating mechanisms, making them more susceptible to iron overload and oxidative stress. This study investigates how iron exposure affects mitochondrial respiration and whether hydrogen sulfide (H₂S) can mitigate these effects. Seahorse XF96 analysis revealed that iron-treated CSE-KO cells exhibited impaired mitochondrial respiration, reduced maximal respiratory capacity, and diminished spare respiratory capacity. In contrast, WT cells maintained a higher spare respiratory capacity, suggesting a protective role of endogenous H₂S. JC-1 staining confirmed that CSE-KO cells undergo mitochondrial dysfunction upon iron exposure with disrupted membrane potential. However, H₂S treatment of CSE-KO cells restored mitochondrial function and prevented membrane depolarization. These findings enhance our understanding of the iron-H₂S interaction in mitochondrial regulation, which can be leveraged for therapeutic strategies to enhance mitochondrial resilience and mitigate iron-induced cellular damage.