Time of day-dependent alterations of ferroptosis in LPS-induced myocardial injury via Bmal-1/AKT/ Nrf2 in rat and H9c2 cell.

BACKGROUND

One of the most prevalent causes of death in sepsis is sepsis-induced cardiomyopathy (SICM). Circadian disruption is involved in the progress of sepsis. However, the molecular mechanism remains unclear.

METHODS

Here, we built LPS-induced SICM and models. LPS was administrated at the particular Zeitgeber times (ZT), ZT4-ZT10-ZT16-ZT22 and ZT10-ZT22 in and experiments, respectively.

RESULTS

In experiment, injection of LPS at ZT10 induced higher infiltration of inflammatory cells and content of intracellular Fe, and lower level of Glutathione peroxidase 4 (GPX4) and cardiac function than other ZTs (P < 0.05), which indicated that myocardial ferroptosis in septic rat presented a time of day-dependent manner. Bmal-1 protein and mRNA levels of injection of LPS at ZT10 were lower than those at other three ZTs (P < 0.05). The ratios of pAKT/AKT at ZT4 and ZT10 LPS injection were lower than those at ZT16 and ZT22 (P < 0.05). Nrf2 protein levels at ZT10 LPS injection were lower than those at other three ZTs (P < 0.05). These results indicated that the circadian of Bmal-1 and its downstream AKT/Nrf2 pathway in rat heart were inhibited under SICM condition. Consistent with experiment, we found LPS could significantly reduce the expressions of Bmal-1 protein and mRNA in H9c2 cell. Up-regulation of Bmal-1 could reduce the cell death, oxidative stress, ferroptosis and activation of AKT/Nrf2 pathway at both ZT10 and ZT22 LPS administration. Conversely, its down-regulation presented opposite effects. AKT siRNA could weaken the effect of Bmal-1 pcDNA.

CONCLUSION

Ferroptosis presented the time of day-dependent manners via Bmal-1/AKT/Nrf2 in and models of SICM.