15-Lipoxygenase-dependent radiomitigation by NO●-Donors suppresses ferroptosis in intestinal Epithelium: Multiomics MS imaging and LC-MS evidence.

Threats of irradiation (IR) exposure increase the need for radiomitigators. An important contributor to radiation injury is ferroptosis, triggered by the disbalanced redox metabolism. We showed that 15-lipoxygenase (15-LOX) catalyzed peroxidation of arachidonoyl-phosphatidyl-ethanolamine is an essential ferroptotic response of ileum to total body IR (TBI). Given that nitric oxide (NO● ) can suppress ferroptosis by inhibiting 15-LOX and by directly scavenging lipid radicals, we tested NO●-donors with optimized half decay times as radiomitigators. Here, we report that diethylenetriamine-NONOate (DETA-NONOate) (with a half decay-time of 20 hr) acted as an effective radiomitigator when administered 24 hr after exposure to TBI (9.25Gy) and markedly prolonged survival of C57BlJ6 mice by - i) decreasing the levels of pro-ferroptotic HOO-PUFA-PE signals, and ii) decreasing the expression of 15-LOX2 - in the ileum on day 4 after TBI. Redox lipidomics LC-MS and two mass spectrometric imaging (MSI) protocols: i) single-cell multi-omics Dual C60/gas cluster ion beam (GCIB) secondary ion mass spectrometry (SIMS), and ii) matrix-assisted laser desorption ionization (MALDI)-MSI, visualized DETA-NONOate's effectiveness in suppressing TBI-induced HOO-PUFA-PE production and preserving intestinal epithelium structural integrity. In vitro, NO● donors were effective in suppressing PUFA-PE peroxidation and ferroptotic death in human intestinal epithelial cells (FHs 74 Int) exposed to radiation (8Gy) plus enzymatic (15-LOX2) pro-ferroptotic stimulation.