Low Dose of β-Carotene Regulates Inflammation, Reduces Caspase Signaling, and Correlates with Autophagy Activation in Cardiomyoblast Cell Lines.

BACKGROUND Excessive reactive oxygen species (ROS) stimulate mitochondrial damage that causes degenerative diseases such as cardiovascular disease (CVD). ß-carotene (BC), a natural antioxidant able to counteract free radicals, acts as a cytoprotective agent. However, knowledge of the role of BC on cardiomyoblasts is limited. In this study, we explored its role on COX4, Tom20, Nfr1, Nrf2, Nf-kappaB, LC3, p62, caspase 3, and caspase 9 and its association with cardiomyoblast viability and survival. MATERIAL AND METHODS H9C2 cell lines were seeded, cultivated until 90% to 100% confluency, and treated with various doses of BC: 10 µM, 1 µM, 0.1 µM, and 0.01 µM. After 24 h, the cells were harvested, lyzed, and tested for specific related protein expressions from each dose. RESULTS Low-dose BC induced autophagy most effectively at 1 µM, 0.1 µM, and 0.01 µM, as indicated by a decrease of LC3II and p62 levels. We observed that Nf-kB protein levels were suppressed; Nrf2 was stimulated, but Nrf1 was not altered significantly. Further, low-dose BC might stimulate cell viability by reducing apoptotic signals of caspase 3 and 9. Notably, low-dose BC also showed potential to increase Tom20 protein levels. CONCLUSIONS Low-dose BC supplementation shows beneficial effects, especially at 0.01 µM, by reducing inflammation through the suppression of Nf-kappaB and increase of Nrf2 level. Autophagy as a cellular maintenance mechanism was also stimulated, and the amount of the mitochondria marker Tom20 increased. Taken together, results showed that specific low-dose BC is effective and might improve cell viability by stimulating autophagy, inhibiting proinflammatory factors, and suppressing apoptosis.