Improved Total-Body Irradiation Survival by Delivery of Two Radiation Mitigators that Target Distinct Cell Death Pathways

Abstract

The acute lethality of total-body irradiation (TBI) involves damage to multiple organs, including bone marrow and intestine. Ionizing radiation mitigators that are effective when delivered 24 h or later after TBI include the anti-apoptotic drug, JP4-039 and the anti-necroptotic drug, necrostatin-1. In contrast to effective delivery of JP4-039 at 24 h after TBI, necrostatin-1 is most effective when delivery is delayed until 48 h, a time that correlates with the elevation of necroptosis-inducing inflammatory cytokines and necroptosis-induced serine phosphorylation of receptor-interacting serine/threonine-protein kinase-3 (RIP3) in tissues. The goal of this work was to determine whether administration of JP4-039 influenced the optimal delivery time for necrostatin-1. We measured daily levels of 33 proteins in plasma compared to intestine and bone marrow of C57BL/6NTac female mice over a 7-day time period after 9.25 Gy TBI (LD). Protein responses to TBI in plasma were different from those measured in intestine or bone marrow. In mice that were given JP4-039 at 24 h after TBI, we delayed necrostatin-1 delivery for 72 h after TBI based on measured delay in RIP-3 kinase elevation in marrow and intestine. Sequential delivery of these two radiation mitigator drugs significantly increased survival compared to single drug administration.

Mechanisms of Action of Autophagy Modulators Dissected by Quantitative Systems Pharmacology Analysis

“…In recent work, we have demonstrated the pivot roles of these targets in regulating distinct cell death pathways [103,[111][112][113]. We also found that due to complex crosstalks among pathways, targeting autophagy, necroptosis, and ferroptosis using polypharmacological strategies can lead to better therapeutic effects in terms of cell survival [114,115]. The present study shows that the key regulators of cell death are targeted by autophagy modulators, in accord with the crosstalk between autophagy and these cell death pathways.…”

Fanconi Anemia Mouse Genotype-specific Mitigation of Total Body Irradiation by GS-Nitroxide JP4-039

“…The dose of TBI delivered was 8.5 Gy. This dose was shown to be the LD 50/30 dose for FA mice and is consistent with the known differences in radiosensitivity of FA mice (1-3).The conditions for irradiation at 310 cGy/min, with filters removed from the cesium irradiator, and dosimetry carried out to ensure uniform dose distribution in mouse phantoms are described elsewhere (18). Conditions for irradiation using a pie-plate animal separator, and specific slots for irradiation, ensuring uniform dose distribution between animals are described therein.…”

“…There are multiple cell death pathways initiated by exposure of cell lines, tissues, and organs to TBI (1,20). Radiation mitigator drugs delivered 24 h after irradiation, which target each of three cell death pathways (apoptosis, necroptosis, and ferroptosis), have been demonstrated to be more effective in increasing survival after TBI than the delivery of one mitigator or administration of two mitigators (18). Those studies also indicated that in TBI, the time of delivery of mitigators targeted to each cell death pathway would be optimized by identification of the biochemical targets for each drug (18).…”

“…The mitochondrial targeted radiation mitigator GS-nitroxide, JP4-039, has been demonstrated to significantly ameliorate the effects of total body irradiation (TBI) of several mouse strains when delivered systemically up to 72 h after (5)(6)(7)(8)(9)(10)(11). Furthermore, in organ-specific radiation protection and mitigation experiments including the oral cavity, mice of three different genotypes on two different mouse background strains with DNA repair-deficient FA revealed therapeutic effects of JP4-039 (1)(2)(3)(12)(13)(14)(15)(16)(17)(18)(19). Radiation dose-response curves showed significant reduction in colony formation in vitro and a radiation-protective effect of JP4-039 in bone marrow stromal and hematopoietic progenitor cell lines as well as fresh bone marrow colony-forming progenitor cells consistent with FA genotype mouse genotype (1-3, 12, 15).…”

Amelioration of Amyotrophic Lateral Sclerosis in SOD1G93AMice by M2Microglia from Transplanted Marrow

“…TBI combined with bone marrow transplantation is a potentially valuable therapeutic option for treating ALS. The subset of donor bone marrow cells (hematopoietic stem cells, committed granulocyte/macrophage progenitors, or mesenchymal stem cells) required to provide the therapeutic effect must also be determined (59,60,63,64,(79)(80)(81)(82).…”