Norepinephrine exacerbates LPS-induced cardiomyopathy via SIRT3/HO-1 axis-mediated ferroptosis

Norepinephrine (NE) is a first-line vasopressor for patients with septic shock, and its overuse can lead to "catecholamine adverse effects", including cardiovascular diseases. Lipopolysaccharide (LPS)-induced cardiomyopathy is one of the leading causes of mortality in septic patients. Previous studies have revealed that catecholamine can accentuate LPS-induced cardiomyopathy, but the underlying mechanisms remain elusive.

Adult mice and H9c2 cells were exposed to LPS and NE. Structural changes, cardiac function and LDH assays were measured to verify the synergistic effects of LPS and NE in vivo and in vitro. Inhibitors of ferroptosis, heme oxygenase-1 (HO-1) and an activator of SIRT3 were used to reverse the synergistic effects. 4-hydroxynonenal (4-HNE)/MDA assays, immunofluorescence, transmission electron microscopy (TEM) and western blotting were used to measure ferroptosis in this study.

In our study, conventional dosage of NE exacerbated LPS-induced cardiomyopathy in long term, followed by ferroptotic alternations of ferrous iron, reactive oxygen species (ROS), mitochondria shrinkage, lipid peroxidation and HO-1 expression. In addition, inhibition of ferroptosis suppressed cardiomyocyte death and cardiomyopathy induced by LPS and NE, indicating the critical contribution of ferroptosis to cardiac injury via the synergistic effects of NE and LPS. Our recent study identified SIRT3 as a therapeutic target for cardiac ferroptosis. In line with this, overexpression of SIRT3 alleviated the death of cardiomyocytes treated with NE + LPS, accompanied by attenuated ferroptosis and HO-1 level. Moreover, the suppression of HO-1 by zinc protoporphyrin (ZnPP) also attenuated ferroptosis in cardiomyocytes treated with NE and LPS.

These data strongly indicate that long-term use of NE can further develop LPS-induced cardiomyopathy via SIRT3/HO-1 axis-mediated ferroptosis.