Genistein nanoparticles protect mouse hematopoietic system and prevent proinflammatory factors after gamma irradiation

A Novel TGFβ Receptor Inhibitor, IPW-5371, Prevents Diet-induced Hepatic Steatosis and Insulin Resistance in Irradiated Mice

As the number of cancer survivors increases and the risk of accidental radiation exposure rises, there is a pressing need to characterize the delayed effects of radiation exposure and develop medical countermeasures. Radiation has been shown to damage adipose progenitor cells and increase liver fibrosis, such that it predisposes patients to developing metabolic-associated fatty liver disease (MAFLD) and insulin resistance. The risk of developing these conditions is compounded by the global rise of diets rich in carbohydrates and fats. Radiation persistently increases the signaling cascade of transforming growth factor β (TGFβ), leading to heightened fibrosis as characteristic of the delayed effects of radiation exposure. We investigate here a potential radiation medical countermeasure, IPW-5371, a small molecule inhibitor of TGFβRI kinase (ALK5). We found that mice exposed to sub-lethal whole-body irradiation and chronic Western diet consumption but treated with IPW-5371 had a similar body weight, food consumption, and fat mass compared to control mice exposed to radiation. The IPW-5371 treated mice maintained lower fibrosis and fat accumulation in the liver, were more responsive to insulin and had lower circulating triglycerides and better muscle endurance. Future studies are needed to verify the improvement by IPW-5371 on the structure and function of other metabolically active tissues such as adipose and skeletal muscle, but these data demonstrate that IPW-5371 protects liver and whole-body health in rodents exposed to radiation and a Western diet, and there may be promise in using IPW-5371 to prevent the development of MAFLD.

Inhibition of the thioredoxin system for radiosensitization therapy of cancer

Radiotherapy (RT) stands as a cornerstone in the clinical armamentarium against various cancers due to its proven efficacy. However, the intrinsic radiation resistance exhibited by cancer cells, coupled with the adverse effects of RT on normal tissues, often compromises its therapeutic potential and leads to unwanted side effects. This comprehensive review aims to consolidate our understanding of how radiosensitizers inhibit the thioredoxin (Trx) system in cellular contexts. Notable radiosensitizers, including gold nanoparticles (GNPs), gold triethylphosphine cyanide ([Au(SCN) (PEt3)]), auranofin, ceria nanoparticles (CONPs), curcumin and its derivatives, piperlongamide, indolequinone derivatives, micheliolide, motexafin gadolinium, and ethane selenide selenidazole derivatives (SeDs), are meticulously elucidated in terms of their applications in radiotherapy. In this review, the sensitization mechanisms and the current research progress of these radiosensitizers are discussed in detail, with the overall aim of providing valuable insights for the judicious application of Trx system inhibitors in the field of cancer radiosensitization therapy.

Multicenter Phase 1b/2a Clinical Trial of Radioprotectant BIO 300 Oral Suspension for Patients With Non-Small Cell Lung Cancer Receiving Concurrent Chemoradiotherapy

PURPOSE

Radiation therapy is part of the standard treatment regimen for non-small cell lung cancer (NSCLC). Although radiation therapy is an effective tool to manage NSCLC, it can be associated with significant dose-limiting toxicities. These toxicities can lead to treatment interruption or early termination and worsening clinical outcomes in addition to reductions in patient quality of life. Based on preclinical efficacy for radioprotection of normal tissues, we evaluated the clinical utility of BIO 300 Oral Suspension (BIO 300; synthetic genistein nanosuspension) in patients with NSCLC.

METHODS AND MATERIALS

In this multicenter, open-label, single-arm, ascending dose phase 1b/2a study, patients were enrolled with newly diagnosed stage II-IV NSCLC planned for 60 to 70/1.8-2.0 Gy radiation therapy and concurrent weekly paclitaxel/carboplatin. Oral BIO 300 (cohort 1, 500 mg/d; cohort 2, 1000 mg/d; cohort 3, 1500 mg/d) was self-administered once daily starting 2 to 7 days before initiating concurrent chemoradiotherapy and continued until the end of radiation therapy. The primary endpoint was acute dose-limiting toxicities attributable to BIO 300. Secondary outcomes included pharmacokinetics, pharmacodynamics, overall toxicity profile, quality of life, local response rate, and survival.

RESULTS

Twenty-one participants were enrolled. No dose-limiting toxicities were reported. BIO 300 dosing did not alter chemotherapy pharmacokinetics. Adverse events were not dose-dependent, and those attributable to BIO 300 (n = 11) were all mild to moderate in severity (grade 1, n = 9; grade 2, n = 2) and predominantly gastrointestinal (n = 7). A dose-dependent decrease in serum transforming growth factor β1 levels was observed across cohorts. Based on safety analysis, the maximum tolerated dose of BIO 300 was not met. Patient-reported quality of life and weight were largely stable throughout the study period. No patient had progression as their best overall response, and a 65% tumor response rate was achieved (20% complete response rate).

CONCLUSIONS

The low toxicity rates, along with the pharmacodynamic results and tumor response rates, support further investigation of BIO 300 as an effective radioprotector.

Polyphenols as Potential Protectors against Radiation-Induced Adverse Effects in Patients with Thoracic Cancer

Radiotherapy is one of the standard treatment approaches used against thoracic cancers, occasionally combined with chemotherapy, immunotherapy and molecular targeted therapy. However, these cancers are often not highly sensitive to standard of care treatments, making the use of high dose radiotherapy necessary, which is linked with high rates of radiation-induced adverse effects in healthy tissues of the thorax. These tissues remain therefore dose-limiting factors in radiation oncology despite recent technological advances in treatment planning and delivery of irradiation. Polyphenols are metabolites found in plants that have been suggested to improve the therapeutic window by sensitizing the tumor to radiotherapy, while simultaneously protecting normal cells from therapy-induced damage by preventing DNA damage, as well as having anti-oxidant, anti-inflammatory or immunomodulatory properties. This review focuses on the radioprotective effect of polyphenols and the molecular mechanisms underlying these effects in the normal tissue, especially in the lung, heart and esophagus.

The delayed effects of acute radiation exposure (DEARE): characteristics, mechanisms, animal models, and promising medical countermeasures

PURPOSE

Terrorist use of nuclear weapons and radiation accidents put the human population at risk for exposure to life-threatening levels of radiation. Victims of lethal radiation exposure face potentially lethal acute injury, while survivors of the acute phase are plagued with chronic debilitating multi-organ injuries for years after exposure. Developing effective medical countermeasures (MCM) for the treatment of radiation exposure is an urgent need that relies heavily on studies conducted in reliable and well-characterized animal models according to the FDA Animal Rule. Although relevant animal models have been developed in several species and four MCM for treatment of the acute radiation syndrome are now FDA-approved, animal models for the delayed effects of acute radiation exposure (DEARE) have only recently been developed, and there are no licensed MCM for DEARE. Herein, we provide a review of the DEARE including key characteristics of the DEARE gleaned from human data as well as animal, mechanisms common to multi-organ DEARE, small and large animal models used to study the DEARE, and promising new or repurposed MCM under development for alleviation of the DEARE.

CONCLUSIONS

Intensification of research efforts and support focused on better understanding of mechanisms and natural history of DEARE are urgently needed. Such knowledge provides the necessary first steps toward the design and development of MCM that effectively alleviate the life-debilitating consequences of the DEARE for the benefit of humankind worldwide.

The Radioprotectant, BIO 300, Protects the Lungs from Total-Body Irradiation Injury in C57L/J Mice

Acute exposure to high dose radiation can cause acute radiation syndrome (ARS), a potentially life-threatening illness. Individuals that survive ARS are at risk of developing the delayed effects of acute radiation exposure, with the lungs being particularly susceptible (DEARE-lung). For individuals at risk of radiation exposure, there are no Food and Drug Administration-approved medical countermeasures (MCMs) for prophylactic or post-exposure use that can prevent or mitigate DEARE-lung. BIO 300 is a novel formulation of synthetic genistein that has been extensively studied as a prophylactic MCM for the hematopoietic subsyndrome of ARS (H-ARS). Here, we used a C57L/J mouse model of total-body irradiation (TBI) to investigate whether prophylactic administration of BIO 300 is able to prevent animals from developing DEARE-lung. Oral and parenteral formulations of BIO 300 administered prior to TBI were compared against standard of care, PEGfilgrastim, administered shortly after radiation exposure, and the combination of oral BIO 300 administered prior to TBI and with PEGfilgrastim administered post-exposure. All animals were exposed to 7.75 Gy cobalt-60 gamma-radiation and the primary endpoint was lung histopathology at 180 days post-TBI. Animals treated with BIO 300 had a significant reduction in the incidence of interstitial lung inflammation compared to vehicle groups for both the oral (0% vs. 47%) and parenteral (13% vs. 44%) routes of administration. Similar results were obtained for the incidence and severity of pulmonary fibrosis in animals treated with oral BIO 300 (incidence, 47% vs. 100% and mean severity score, 0.53 vs. 1.3) and parenteral BIO 300 (incidence, 63% vs. 100% and mean severity score, 0.69 vs. 1.7). PEGfilgrastim alone had no significant effect in reducing the incidence of inflammation or fibrosis compared to vehicle. The combination of oral BIO 300 and PEGfilgrastim significantly reduced the incidence of interstitial inflammation (13% vs. 46%) and the severity of pulmonary fibrosis (mean severity score, 0.93 vs. 1.6). Results in the C57L/J mice were compared to those in CD2F1 mice, which are less prone to lung injury following total-body irradiation. Taken together, these studies indicate that BIO 300 is a promising MCM that is able to prophylactically protect against DEARE-lung.

Safety, Pharmacokinetics, and Biomarkers of an Amorphous Solid Dispersion of Genistein, a Radioprotectant, in Healthy Volunteers

A pharmaceutical formulation of genistein, produced as an amorphous solid dispersion by hot melt extrusion (genistein HME), has been developed that can be administered prophylactically to improve outcomes and survival following radiation exposure. Here, genistein HME was evaluated in a phase 1, open-label, single ascending dose (SAD) and multiple single dose (MSD) study enrolling 34 healthy volunteers. In the SAD study, participants were administered a single dose (500, 1000, 2000, or 3000 mg) and in the MSD study, participants were administered a single daily dose for six consecutive days (3000 mg/day). The overall adverse event profile and pharmacokinetics of genistein HME were determined. Additionally, biomarkers of genistein HME were evaluated by profiling whole blood for changes in gene expression by RNA sequencing. Genistein HME was found to be safe at doses up to 3000 mg. Most toxicities were mild to moderate gastrointestinal events, and no dose-limiting toxicities were reported. The maximum tolerated dose was not determined and the no observable adverse effect level was 500 mg. Genistein HME bioavailability greatly increased between the 2000 mg and 3000 mg doses. RNA sequencing analysis revealed that the majority of drug-related changes in gene expression occurred 8-12 hours after the sixth dose in the MSD study. Based on these results, the putative effective dose in humans is 3000 mg.

Design of Monovalent Cerium-Based Metal Organic Frameworks as Bioinspired Superoxide Dismutase Mimics for Ionizing Radiation Protection

Superoxide dismutase (SOD) is one of the major antioxidants in vivo and is expected to play critical roles on the defense against reactive oxygen species (ROS)-mediated damages, such as ionizing radiation damages. Herein, inspired by the function and structure of natural SODs and cerium oxide nanozymes, two monovalent cerium-based metal organic frameworks (Ce-MOFs), Ce^IIIBTC and Ce^IVBTC, were designed for superoxide radical (O₂^•-) elimination and ionizing radiation protection. These two Ce-MOFs selectively scavenge O₂^•- and are excellent SOD mimics. Like natural SODs and cerium oxide nanozymes, the SOD-like catalytic mechanism of Ce-MOFs involves a cycle between Ce(IV) and Ce(III). Furthermore, by constructing monovalent Ce-MOFs, we found that high-valent Ce^IVBTC are more effective SOD-like nanozymes compared to Ce^IIIBTC. With smaller size, better monodispersity, and more effective SOD-like activity, Ce^IVBTC nanozymes were further applied for ionizing radiation protection. Both in vitro and in vivo results demonstrated that Ce^IVBTC nanozymes could efficiently scavenge ROS, prevent cells from γ-ray radiation-induced cell viability decrease and DNA damages, and improve the survival rate of irradiated mice by recovering the bone marrow DNA damage and alleviating oxidative stress of tissues. The protective effect and good biocompatibility of Ce^IVBTC nanozymes will enable the development of Ce-MOFs-based radioprotectants and facilitate treatment of other ROS-related diseases.

Protection of the hematopoietic system against radiation-induced damage: drugs, mechanisms, and developments

Sometimes, people can be exposed to moderate or high doses of radiation accidentally or through the environment. Radiation can cause great harm to several systems within organisms, especially the hematopoietic system. Several types of drugs protect the hematopoietic system against radiation damage in different ways. They can be classified as "synthetic drugs" and "natural compounds." Their cellular mechanisms to protect organisms from radiation damage include free radical-scavenging, anti-oxidation, reducing genotoxicity and apoptosis, and alleviating suppression of the bone marrow. These topics have been reviewed to provide new ideas for the development and research of drugs alleviating radiation-induced damage to the hematopoietic system.

Pharmacokinetic and metabolomic studies with a BIO 300 Oral Powder formulation in nonhuman primates

BIO 300, a pharmaceutical formulation of genistein, is being developed as a radiation countermeasure to treat hematopoietic acute radiation syndrome (H-ARS) and the delayed effects of acute radiation exposure (DEARE). Several studies have affirmed its safety and efficacy in alleviating the damaging effects of ionizing radiation. However, dose optimization of any drug has always been an important area of research because unnecessarily high drug doses may result in serious complications. In this study, we assessed the pharmacokinetics (PK) and metabolic profiles of two different doses of a novel solid-dosage formulation of BIO 300 (BIO 300 Oral Powder; 100 mg/kg and 200 mg/kg), when administered orally to nonhuman primates (NHPs). While the T_max values of both doses remained the same, the area under the curve at 48 h (AUC_0-48) was tripled by doubling the dose. Additionally, we monitored serum samples for global metabolomic/lipidomic changes using high resolution mass spectrometry followed by functional pathway analysis prior to and at various time points up to 48 h post drug administration. Interestingly, the metabolomic profiles of sera from NHPs that received the lower dose demonstrated a transient perturbation in numerous metabolites between the 4 and 12 h time points. Eventually, the metabolite abundance reverted to near-normal by 48 h. These study results are consistent with our previous studies focused on the PK and metabolomic analysis for parenteral and oral aqueous nanosuspension formulations of BIO 300. This study affirms that administration of a single dose of up to 200 mg/kg of BIO 300 Oral Powder is safe in NHPs and conferred no metabolomic-mediated safety features.

Nuclear and Radiological Emergencies: Biological Effects, Countermeasures and Biodosimetry

Atomic and radiological crises can be caused by accidents, military activities, terrorist assaults involving atomic installations, the explosion of nuclear devices, or the utilization of concealed radiation exposure devices. Direct damage is caused when radiation interacts directly with cellular components. Indirect effects are mainly caused by the generation of reactive oxygen species due to radiolysis of water molecules. Acute and persistent oxidative stress associates to radiation-induced biological damages. Biological impacts of atomic radiation exposure can be deterministic (in a period range a posteriori of the event and because of destructive tissue/organ harm) or stochastic (irregular, for example cell mutation related pathologies and heritable infections). Potential countermeasures according to a specific scenario require considering basic issues, e.g., the type of radiation, people directly affected and first responders, range of doses received and whether the exposure or contamination has affected the total body or is partial. This review focuses on available medical countermeasures (radioprotectors, radiomitigators, radionuclide scavengers), biodosimetry (biological and biophysical techniques that can be quantitatively correlated with the magnitude of the radiation dose received), and strategies to implement the response to an accidental radiation exposure. In the case of large-scale atomic or radiological events, the most ideal choice for triage, dose assessment and victim classification, is the utilization of global biodosimetry networks, in combination with the automation of strategies based on modular platforms.

Interspecies Comparison and Radiation Effect on Pharmacokinetics of BIO 300, a Nanosuspension of Genistein, after Different Routes of Administration in Mice and Non-Human Primates

BIO 300, a suspension of synthetic genistein nanoparticles, is being developed for mitigating the delayed effects of acute radiation exposure (DEARE). The purpose of the current study was to characterize the pharmacokinetic (PK) profile of BIO 300 administered as an oral or parenteral formulation 24 h after sham-irradiation, total-body irradiation (TBI) with 2.5-5.0% bone marrow sparing (TBI/BMx), or in nonirradiated sex-matched C57BL/6J mice and non-human primates (NHP). C57BL/6J mice were randomized to the following arms in two consecutive studies: sham-TBI [400 mg/kg, oral gavage (OG)], TBI/BM2.5 (400 mg/kg, OG), sham-TBI [200 mg/kg, subcutaneous (SC) injection], TBI/BM2.5 (200 mg/kg, SC), sham-TBI (100 mg/kg, SC), or nonirradiated [200 mg/kg, intramuscular (IM) injection]. The PK profile was also established in NHP exposed to TBI/BM5.0 (100 mg/kg, BID, OG). Genistein-aglycone serum concentrations were measured in all groups using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay. The PK profile demonstrates 11% and 19% reductions in Cmax and AUC0-inf, respectively, among mice administered 400 mg/kg, OG, after TBI/BM2.5 compared to the sham-TBI control arm. Administration of 200 mg/kg SC in mice exposed to TBI/BM2.5 showed a 53% increase in AUC0-inf but a 28% reduction in Cmax compared to the sham-TBI mice. The relative bioavailability of the OG route compared to the SC and IM routes in mice was 9% and 7%, respectively. After the OG route, the dose-normalized AUC0-inf was 13.37 (ng.h/mL)/(mg/kg) in TBI/BM2.5 mice compared to 6.95 (ng.h/mL)/(mg/kg) in TBI/BM5.0 NHPs. Linear regression of apparent clearances and weights of mice and NHPs yielded an allometric coefficient of 1.06. Based on these data, the effect of TBI/BMx on BIO 300 PK is considered minimal. Future studies should use SC and IM routes to maximize drug exposure when administered postirradiation. The allometric coefficient is useful in predicting therapeutic drug dose regimens across species for drug approval under the FDA animal rule.

Microbiome study in irradiated mice treated with BIO 300, a promising radiation countermeasure

Background

The mammalian gut harbors very complex and diverse microbiota that play an important role in intestinal homeostasis and host health. Exposure to radiation results in dysbiosis of the gut microbiota leading to detrimental pathophysiological changes to the host. To alleviate the effects of irradiation, several candidate countermeasures are under investigation. BIO 300, containing synthetic genistein formulated as an amorphous solid dispersion or as an aqueous suspension of nanoparticles, is a promising candidate under advanced development. The aim of this study was to investigate the effects of BIO 300 on the gut microbiome and metabolome of mice exposed to ⁶⁰Co gamma-radiation. The gut microbiota and metabolome of control and drug-treated mice exposed to radiation was characterized by bacterial 16S rRNA amplicon sequencing and untargeted metabolomics.

Results

We found that irradiation altered the Firmicutes/Bacteroidetes ratio and significantly decreased the relative abundance of Lactobacillus, both in BIO 300-treated and control mice; however, the ratio returned to near normal levels in BIO 300-treated mice by day 14 post-irradiation. Concomitantly, we also observed corrective shifts in metabolic pathways that were perturbed after irradiation.

Conclusions

Overall, the data presented show that radiation exposure led to a relative depletion of commensals like Lactobacillus leading to an inflammatory metabolic phenotype while the majority of the drug-treated mice showed alleviation of this condition primarily by restoration of normal gut microbiota. These results indicate that the radioprotective effects of BIO 300, at least in part, may involve correction of the host-microbiome metabolic axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-021-00132-1.

A novel oral formulation of BIO 300 confers prophylactic radioprotection from acute radiation syndrome in mice

PURPOSE

Exposure to high doses of ionizing radiation can result in hematopoietic acute radiation syndrome (H-ARS) and delayed effects of acute radiation exposure (DEARE). There is no radiation medical countermeasure (MCM) approved by the U.S. Food and Drug Administration which can be used prior to radiation exposure to protect exposed individuals. Different formulations containing synthetic genistein (BIO 300) are being developed to counter the harmful effects of radiation exposure.

MATERIALS AND METHODS

We investigated the efficacy of a BIO 300 oral powder (OP) formulation as a prophylactic radiation MCM against a lethal dose of cobalt-60 gamma-radiation in CD2F1 male mice while comparing to other formulations of BIO 300 and Neulasta (PEGylated filgrastim), a standard of care drug for H-ARS.

RESULTS

BIO 300 OP provided significant radioprotection against ionizing radiation in mice when administered twice per day for six days prior to total-body radiation exposure. Its radioprotective efficacy in the murine model was comparable to the efficacy of a single subcutaneous (sc) injection of Neulasta administered after total-body radiation exposure.

CONCLUSIONS

Our results demonstrate that BIO 300 OP, which can be administered orally, is a promising prophylactic radiation countermeasure for H-ARS.

A Trans-Agency Workshop on the Pathophysiology of Radiation-Induced Lung Injury

Research and development of medical countermeasures (MCMs) for radiation-induced lung injury relies on the availability of animal models with well-characterized pathophysiology, allowing effective bridging to humans. To develop useful animal models, it is important to understand the clinical condition, advantages and limitations of individual models, and how to properly apply these models to demonstrate MCM efficacy. On March 20, 2019, a meeting sponsored by the Radiation and Nuclear Countermeasures Program (RNCP) within the National Institute of Allergy and Infectious Diseases (NIAID) brought together medical, scientific and regulatory communities, including academic and industry subject matter experts, and government stakeholders from the Food and Drug Administration (FDA) and the Biomedical Advanced Research and Development Authority (BARDA), to identify critical research gaps, discuss current clinical practices for various forms of pulmonary damage, and consider available animal models for radiation-induced lung injury.

Genistein From Fructus sophorae Protects Mice From Radiation-Induced Intestinal Injury

The development of an effective pharmacological countermeasure is needed to reduce the morbidity and mortality in high-dose ionizing radiation-induced acute damage. Genistein has shown bioactivity in alleviating radiation damage and is currently synthesized by chemosynthetic methods. Due to concerns about chemical residues and high costs, the clinical application of genistein is still a major challenge. In this study, we aimed to establish an efficient method for the extraction of genistein from Fructus sophorae. The effects of extracted genistein (FSGen) on preventing intestinal injury from radiation were further investigated in this study. C57/BL mice were exposed to 7.5 Gy whole body irradiation with and without FSGen treatments. Histological analysis demonstrated significant structural and functional restitution of the intestine and bone marrow in FSGen-pretreated cohorts after irradiation. Through mRNA expression, protein expression, and small interfering RNA analyses, we demonstrated that FSGen protects IEC-6 cells against radiation damage by upregulating the Rassf1a and Ercc1 genes to effectively attenuate DNA irradiation damage. Together, our data established an effective method to extract genistein from the Fructus sophorae plant with high purity, and validated the beneficial roles of the FSGen in protecting the radiation damage. These results promise the future applications of Fructus sophorae extracted genistein in the protection of radiation related damages.

Rational Design of Nanomaterials for Various Radiation-Induced Diseases Prevention and Treatment

Radiation treatments often unfavorably damage neighboring healthy organs and cause a series of radiation sequelae, such as radiation-induced hematopoietic system diseases, radiation-induced gastrointestinal diseases, radiation-induced lung diseases, and radiation-induced skin diseases. Recently, emerging nanomaterials have exhibited good superiority for these radiation-induced disease treatments. Given this background, the rational design principle of nanomaterials, which helps to optimize the therapeutic efficiency, has been an increasing need. Consequently, it is of great significance to perform a systematic summarization of the advances in this field, which can trigger the development of new high-performance nanoradioprotectors with drug efficiency maximization. Herein, this review highlights the advances and perspectives in the rational design of nanomaterials for preventing and treating various common radiation-induced diseases. Furthermore, the sources, clinical symptoms, and pathogenesis/injury mechanisms of these radiation-induced diseases will also be introduced. Furthermore, current challenges and directions for future efforts in this field are also discussed.

BIO 300: a promising radiation countermeasure under advanced development for acute radiation syndrome and the delayed effects of acute radiation exposure

INTRODUCTION

There are no radioprotectors currently approved by the United States Food and Drug Administration (US FDA) for either the hematopoietic acute radiation syndrome (H-ARS) or for the acute radiation gastrointestinal syndrome (GI-ARS). There are currently, however, three US FDA-approved medicinals that serve to mitigate acute irradiation-associated hematopoietic injury.

AREA COVERED

We present the current status of a promising radiation countermeasure, BIO 300 (a genistein-based agent), that has been extensively investigated in murine models of H-ARS and models of the delayed effects of acute radiation exposure (DEARE) and is currently being evaluated in large animal models. It is also being developed for the prevention of radiation-induced toxicities associated with solid tumor radiotherapy and is the subject of two active Investigational New Drug (IND) applications. We have included a listing and brief review of significant investigations of this promising medical countermeasure.

EXPERT OPINION

BIO 300 is a leading radioprotector under advanced development for H-ARS and DEARE, as well as for select oncologic indication(s). Efficacy following oral administration (po), lack of clinical side effects, storage at ambient temperature, and intended dual use makes BIO 300 an ideal candidate for military and civilian use as well as for storage in the Strategic National Stockpile.

Pre-clinical evaluation of an innovative oral nano-formulation of baicalein for modulation of radiation responses

There is an unmet medical need for non-toxic and effective radiation countermeasures for prevention of radiation toxicity during planned exposures. We have earlier shown that intraperitoneal administration of baicalein (BCL) offers significant survival benefit in animal model. Safety, tolerability, pharmacokinetics (PK) and pharmacodynamics of baicalein has been reported in pre-clinical model systems and also in healthy human volunteers. However, clinical translation of baicalein is hindered owing to poor bioavailability due to lipophilicity. In view of this, we fabricated and characterized in-situ solid lipid nanoparticles of baicalein (SLNB) with effective drug entrapment and release kinetics. SLNB offered significant protection to murine splenic lymphocytes against 4 Gy ionizing radiation (IR) induced apoptosis. Oral administration of SLNB exhibited ~70% protection to mice against whole body irradiation (WBI 7.5 Gy) induced mortality. Oral relative bioavailability of BCL was enhanced by over ~300% after entrapment in the SLNB as compared to BCL. Oral dosing of SLNB resulted in transient increase in neutrophil abundance in peripheral blood. Interestingly, we observed that treatment of human lung cancer cells (A549) with radioprotective dose of SLNB exhibited radio-sensitization as evinced by decrease in survival and clonogenic potential. Contrary to antioxidant nature of baicalein in normal cells, SLNB treatment induced significant increase in cellular ROS levels in A549 cells probably due to higher uptake and inhibition of TrxR. Thus, a pharmaceutically acceptable SLNB exhibited improved bioavailability, better radioprotection to normal cells and sensitized cancer cells to radiation induced killing as compared to BCL suggesting its possible utility as an adjuvant during cancer radiotherapy.

Comparative proteomic analysis of serum from nonhuman primates administered BIO 300: a promising radiation countermeasure

Hematopoietic acute radiation syndrome (H-ARS) and delayed effects of acute radiation exposure (DEARE) are detrimental health effects that occur after exposure to high doses of ionizing radiation. BIO 300, a synthetic genistein nanosuspension, was previously proven safe and effective against H-ARS when administered (via the oral (po) or intramuscular (im) route) prior to exposure to lethal doses of total-body radiation. In this study, we evaluated the proteomic changes in serum of nonhuman primates (NHP) after administering BIO 300 by different routes (po and im). We utilized nanoflow-ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (NanoUPLC-MS/MS) methods for comprehensive global profiling and quantification of serum proteins. The results corroborate previous findings that suggest a very similar metabolic profile following both routes of drug administration. Furthermore, we observed minor alterations in protein levels, 2 hours after drug administration, which relates to the C_max of BIO 300 for both routes of administration. Taken together, this assessment may provide an insight into the mechanism of radioprotection of BIO 300 and a reasonable illustration of the pharmacodynamics of this radiation countermeasure.

Pharmacological management of ionizing radiation injuries: current and prospective agents and targeted organ systems

Introduction: There is a limited array of currently available medicinals that are useful for either the prevention, mitigation or treatment of bodily injuries arising from ionizing radiation exposure.Area covered: In this brief article, the authors review those pharmacologic agents that either are currently being used to counter the injurious effects of radiation exposure, or those that show promise and are currently under development.Expert opinion: Although significant, but limited progress has been made in the development and fielding of safe and effective pharmacotherapeutics for select types of acute radiation-associated injuries, additional effort is needed to broaden the scope of drug development so that overall health risks associated with both short- and long-term injuries in various organ systems can be reduced and effectively managed. There are several promising radiation countermeasures that may gain regulatory approval from the government in the near future for use in clinical settings and in the aftermath of nuclear/radiological exposure contingencies.

Mechanism and therapeutic window of a genistein nanosuspension to protect against hematopoietic-acute radiation syndrome

There are no FDA-approved drugs that can be administered prior to ionizing radiation exposure to prevent hematopoietic-acute radiation syndrome (H-ARS). A suspension of synthetic genistein nanoparticles was previously shown to be an effective radioprotectant against H-ARS when administered prior to exposure to a lethal dose of total body radiation. Here we aimed to determine the time to protection and the duration of protection when the genistein nanosuspension was administered by intramuscular injection, and we also investigated the drug's mechanism of action. A single intramuscular injection of the genistein nanosuspension was an effective radioprotectant when given prophylactically 48 h to 12 h before irradiation, with maximum effectiveness occurring when administered 24 h before. No survival advantage was observed in animals administered only a single dose of drug after irradiation. The dose reduction factor of the genistein nanosuspension was determined by comparing the survival of treated and untreated animals following different doses of total body irradiation. As genistein is a selective estrogen receptor beta agonist, we also explored whether this was a central component of its radioprotective mechanism of action. Mice that received an intramuscular injection of an estrogen receptor antagonist (ICI 182,780) prior to administration of the genistein nanosuspension had significantly lower survival following total body irradiation compared with animals only receiving the nanosuspension (P < 0.01). These data define the time to and duration of radioprotection following a single intramuscular injection of the genistein nanosuspension and identify its likely mechanism of action.

Pharmacokinetic and Metabolomic Studies with BIO 300, a Nanosuspension of Genistein, in a Nonhuman Primate Model

Genistein is a naturally occurring phytoestrogen isoflavone and is the active drug ingredient in BIO 300, a radiation countermeasure under advanced development for acute radiation syndrome (H-ARS) and for the delayed effects of acute radiation exposure (DEARE). Here we have assessed the pharmacokinetics (PK) and safety of BIO 300 in the nonhuman primate (NHP). In addition, we analyzed serum samples from animals receiving a single dose of BIO 300 for global metabolomic changes using ultra-performance liquid chromatography (UPLC) quadrupole time-of-flight mass spectrometry (QTOF-MS). We present a comparison of how either intramuscularly (im) or orally (po) administered BIO 300 changed the metabolomic profile. We observed transient alterations in phenylalanine, tyrosine, glycerophosphocholine, and glycerophosphoserine which reverted back to near-normal levels 7 days after drug administration. We found a significant overlap in the metabolite profile changes induced by each route of administration; with the po route showing fewer metabolic alterations. Taken together, our results suggest that the administration of BIO 300 results in metabolic shifts that could provide an overall advantage to combat radiation injury. This initial assessment also highlights the utility of metabolomics and lipidomics to determine the underlying physiological mechanisms involved in the radioprotective efficacy of BIO 300.

Graphdiyne Nanoparticles with High Free Radical Scavenging Activity for Radiation Protection

Numerous carbon networks materials comprised of benzene moieties, such as graphene and fullerene, have held great fascination for radioprotection because of their acknowledged good biocompatibility and strong free radical scavenging activity derived from their delocalized π-conjugated structure. Recently, graphdiyne, a new emerging carbon network material consisting of a unique chemical structure of benzene and acetylenic moieties, has gradually attracted attention in many research fields. Encouraged by its unique structure with strong conjugated π-system and highly reactive diacetylenic linkages, graphdiyne might have free radical activity and can thus be used as a radioprotector, which has not been investigated so far. Herein, for the first time, we synthesized bovine serum albumin (BSA)-modified graphdiyne nanoparticles (graphdiyne-BSA NPs) to evaluate their free radical scavenging ability and investigate their application for radioprotection both in cell and animal models. In vitro studies indicated that the graphdiyne-BSA NPs could effectively eliminate the free-radicals, decrease radiation-induced DNA damage in cells, and improve the viability of cells under ionizing radiation. In vivo experiments showed that the graphdiyne-BSA NPs could protect the bone marrow DNA of mice from radiation-induced damage and make the superoxide dismutase (SOD) and malondialdehyde (MDA) (two kinds of vital indicators of radiation-induced injury) recover back to normal levels. Furthermore, the good biocompatibility and negligible systemically toxicity responses of the graphdiyne-BSA NPs to mice were verified. All these results manifest the good biosafety and radioprotection activity of graphdiyne-BSA NPs to normal tissues. Therefore, our studies not only provide a new radiation protection platform based on graphdiyne for protecting normal tissues from radiation-caused injury but also provide a promising direction for the application of graphdiyne in the biomedicine field.

Comparison of liver gene expression by RNAseq and PCR analysis after 8 weeks of feeding soy protein isolate- or casein-based diets in an obese liver steatosis rat model

Differential expression of genes provides insight into fundamental mechanisms associated with the ability of soy protein isolate to attenuate liver steatosis in genetically obese rats.

Pharmacology of natural radioprotectors

Radiotherapy is one of the most efficient ways to treat cancer. However, deleterious effects, such as acute and chronic toxicities that reduce the quality of life, may result. Naturally occurring compounds have been shown to be non-toxic over wide dose ranges and are inexpensive and effective. Additionally, pharmacological strategies have been developed that use radioprotectors to inhibit radiation-induced toxicities. Currently available radioprotectors have several limitations, including toxicity. In this review, we present the mechanisms of proven radioprotectors, ranging from free radical scavenging (the best-known mechanism of radioprotection) to molecular-based radioprotection (e.g., upregulating expression of heat shock proteins). Finally, we discuss naturally occurring compounds with radioprotective properties in the context of these mechanisms.

Effects of Low-to-Moderate Doses of Gamma Radiation on Mouse Hematopoietic System

In this study, we investigated the effects of low-to-moderate doses of radiation in mice, given our limited understanding of the health risks associated with these exposures. Here, we demonstrate the different responses of the CD2F1 mouse hematopoietic system to low-to-moderate (0.5, 1, 3 or 5 Gy) doses of gamma radiation. After 3 and 5 Gy of ⁶⁰Co total-body irradiation (TBI), mouse blood cell counts were decreased and maintained below baseline up to 28-42 days. In contrast, after 0.5 Gy TBI, lymphocyte and monocyte counts increased, and peaked from day 3 to day 14. Radiation doses at 0.5 and 1 Gy did not cause cell death or T-cell subpopulation changes in spleen and thymus, whereas the clonogenicity of mouse bone marrow (BM) progenitor cells was significantly suppressed on the first day after 0.5-5 Gy TBI, and these low levels were maintained up to 42 days. Although a transient recovery in total colony forming units (CFUs) was shown in mouse BM at days 14 and 21 after 0.5 Gy TBI, the early-stage multipotential progenitor colonies (CFU-GEMM) remained at a significantly low level compared to those of the sham-irradiated (0 Gy) controls. Consistently, the level of stem cell factor (SCF) in BM cells was decreased after low-to-moderate TBI. Serum from individual mice was collected after irradiation and 23 cytokines/chemokines were measured; massive releases of cytokines and chemokines were observed at day 3 postirradiation in a dose-dependent manner. When human hematopoietic CD34⁺ cells were cultured with the serum collected from mice irradiated at different doses, a significant decrease of CFU-GEMM colonies in the CD34⁺ cells was observed. Our data suggest that low-to-moderate doses of radiation induced cellular responses that are cell type-dependent. The early stage multipotential progenitor cells in mouse BM were the most sensitive cells even to low-dose irradiation compared to spleen and thymic cells, and 0.5 Gy TBI induced hematopoietic cell injury from day 1 to the end of our experiment, day 42 postirradiation. Radiation-induced decrease of SCF in mouse BM and increase in circulating pro-inflammatory factors may be responsible for the enhanced sensitivity of hematopoietic progenitor cells to radiation.

Application of Multifunctional Nanomaterials in Radioprotection of Healthy Tissues

Radiotherapy has been extensively used in clinic for malignant tumors treatment. However, a severe challenge of it is that the ionizing radiation needed to kill tumors inevitably causes damage to surrounding normal tissues. Although some of the molecular radioprotective drugs, such as amifostine, have been used as clinical adjuvants to radio-protect healthy tissues, their shortcomings such as short systemic circulation time and fast biological clearing from the body largely hinder the sustained bioactivity. Recently, with the rapid development of nanotechnology in the biological field, the multifunctional nanomaterials not only establish powerful drug delivery systems to improve the molecular radioprotective drugs' biological availability, but also open a new route to develop neozoic radioprotective agents because some nanoparticles possess intrinsic radioprotective abilities. Therefore, considering these overwhelming superiorities, this review systematically summarizes the advances in healthy tissue radioprotection applications of multifunctional nanomaterials. Furthermore, this review also points out a perspective of nanomaterial designs for radioprotection applications and discusses the challenges and future outlooks of the nanomaterial-mediated radioprotection.

17α-Ethinyl-androst-5-ene-3β, 17β-diol, a Novel Potent Oral Radioprotective Agent, Confers Radioprotection of Hematopoietic Stem and Progenitor Cells in a Granulocyte Colony-Stimulating Factor-Independent Manner

PURPOSE

The risk of radiation exposure is considered to have increased in recent years. For convenience and simple administration, development of an effective orally administered radioprotective agent is highly desirable. The steroid 5-androstene-3β, 17β-diol (5-AED) has been evaluated as both a radioprotector and a radiomitigator in mice and nonhuman primates; however, poor oral bioavailability has limited its development. A variant compound-17α-ethinyl-androst-5-ene-3β, 17β-diol (EAD)-exhibits significant oral bioavailability. We investigated the radioprotective effects of EAD via oral administration in mice.

METHODS AND MATERIALS

Survival assays were performed in lethally (9.0-10.0 Gy) irradiated mice. Peripheral blood cell counts were monitored in lethally (9.5 Gy) or sublethally (6.5 Gy) irradiated mice. We performed histologic analysis of bone marrow (BM) and frequency and functional analysis of hematopoietic stem and progenitor cells in mice irradiated with 6.5 Gy. To investigate multilineage engraftment of irradiated hematopoietic stem cells after BM transplantation, competitive repopulation assays were conducted. Plasma granulocyte colony-stimulating factor was measured by enzyme-linked immunosorbent assay.

RESULTS

Oral administration of EAD on 3 consecutive days before irradiation conferred 100% survival in mice, against otherwise 100% death, at a 9.5-Gy lethal dose of total body irradiation. EAD ameliorated radiation-induced pancytopenia at the same dose. EAD augmented BM cellular recovery and colony-forming ability, promoted hematopoietic stem and progenitor cell recovery, and expanded the pool of functionally superior hematopoietic stem cells in the BM of sublethally irradiated mice. Unlike 5-AED, EAD did not increase granulocyte colony-stimulating factor levels in mice and exhibited no therapeutic effects on hematologic recovery after irradiation; nevertheless, its radioprotective efficacy was superior to that of 5-AED.

CONCLUSIONS

Our findings demonstrate the radioprotective efficacy of EAD and reveal that the 17α-ethinyl group is essential for its oral activity. Given its oral efficacy and low toxicity, EAD has potential as an optimal radioprotector for use by first responders, as well as at-risk civilian populations.

ERα promotes murine hematopoietic regeneration through the Ire1α-mediated unfolded protein response

Activation of the unfolded protein response (UPR) sustains protein homeostasis (proteostasis) and plays a fundamental role in tissue maintenance and longevity of organisms. Long-range control of UPR activation has been demonstrated in invertebrates, but such mechanisms in mammals remain elusive. Here, we show that the female sex hormone estrogen regulates the UPR in hematopoietic stem cells (HSCs). Estrogen treatment increases the capacity of HSCs to regenerate the hematopoietic system upon transplantation and accelerates regeneration after irradiation. We found that estrogen signals through estrogen receptor α (ERα) expressed in hematopoietic cells to activate the protective Ire1α-Xbp1 branch of the UPR. Further, ERα-mediated activation of the Ire1α-Xbp1 pathway confers HSCs with resistance against proteotoxic stress and promotes regeneration. Our findings reveal a systemic mechanism through which HSC function is augmented for hematopoietic regeneration.

Qualitative and quantitative analysis of catechin and quercetin in flavonoids extracted from Rosa roxburghii Tratt

Purpose

To perform a qualitative and quantitative analysis of catechin and quercetin in flavonoids extracted from Rosa roxburghii Tratt.

Methods

Total flavonoids were determined using ultraviolet spectrophotometry (UV) at 500 nm. The optimal gradient program started with 15 % methanol and was kept within a period of 0 – 20 min, while 25 % methanol was kept within 20 – 33 min. Subsequently, the concentration of methanol was reduced to 15 % and was held for 10 min until the next injection. Mass spectrometry spray voltage was 4,000 V, ionization temperature 350 °C, atomizer pressure 35 psi, nitrogen flow rate 8 L/min, and mass scan range 200 – 800 m/z. The detection wavelength used for catechin and quercetin was 270 and 368 nm, respectively.

Results

Based on the UV results, Rosa roxburghii Tratt content was 73.85 %, which is in agreement with the national standard. Liquid chromatography-mass spectrometry (LC-MS) results indicate that Rosa roxburghii Tratt flavonoids contained quercetin, 34.26 %, with relative standard deviation (RSD) of 2.88 % and catechin content of 2.97 % with RSD of 1.49 %.

Conclusion

The proposed measurement method for determining the content of flavonoids in Rosa roxburghii Tratt has the advantage of simplicity, feasibility, good repeatability, and rapid and accurate analysis.

Cholinergic and cytoprotective signaling cascades mediate the mitigative effect of erythropoietin on acute radiation syndrome

The present investigation aimed to evaluate the radiomitigative efficacy of the recombinant human erythropoietin (EPO) against acute radiation syndrome (ARS) in a rat model. Rats were irradiated with a single sublethal dose of γ-radiation (7 Gy; total body irradiation; TBI) on the 1st day of experimental course, then received EPO (5000 IU/kg; i.p.) 24 h after irradiation, and rats were observed for 30 days of survival analysis. Administration of EPO improved 30-day survival, alleviated TBI-induced myelosuppression and pancytopenia, by augmenting lymphocytes and other white blood cells in the peripheral blood of rats, while bone marrow and spleen cellularity were restored. EPO post-exposure treatment alleviated hepatotoxicity biomarkers and restored splenic function. EPO abrogated radiation-induced oxidative stress through the upregulation of the cholinergic anti-inflammatory nicotinic acetylcholine receptor (α-7-nAChR) and the pro-survival Janus kinase-2 and signal transducers and activators of transcription JAK-2/STAT-3 signaling mediated via enhancing nuclear factor erythroid-2 related factor-2 (Nrf-2) cytoprotective machinery in liver and spleen of irradiated rats. Moreover, EPO treatment prevented hepatic and splenic apoptosis. The present study establishes the implication of α-7-nAChR-JAK-2/STAT-3-Nrf-2 signaling cascade in the radiomitigative potential of EPO against ARS.

Role of drugs in the prevention and amelioration of radiation induced toxic effects

As the use of radiation technology for nuclear warfare or for the benefits of mankind (e.g. in radiotherapy or radio-diagnosis) is increasing tremendously, the risk of associated side effects is becoming a cause of concern. These effects, ranging from nausea/vomiting to death, may result from accidental or deliberate exposure and begin in seconds. Through this review paper, efforts have been done to critically review different compounds which have been investigated as radioprotectors and radiation mitigators. Radioprotectors are compounds which are administered just before or at the time of irradiation so as to minimize the radiation induced damage to normal tissues. And radiation mitigators are the compounds which can even minimize or ameliorate post irradiaion-toxicity provided they are administered before the onset of toxic symptoms. A variety of agents have been investigated for their preventive and ameliorative potential against radiation induced toxic effects. This review article has focused on various aspects of the promising representative agents belonging to different classes of radioprotectors and mitigators. Many compounds have shown promising results, but till date only amifostine and palifermin are clinically approved by FDA. To fill this void in pharmacological armamentarium, focus should be shifted towards novel approaches.

BIO 300, a nanosuspension of genistein, mitigates pneumonitis/fibrosis following high-dose radiation exposure in the C57L/J murine model

BACKGROUND AND PURPOSE

BIO 300 nanosuspension (Humanetics Corporation) is being developed as a medical countermeasure (MCM) for the mitigation of the delayed effects of acute radiation exposure, specifically pneumonitis and fibrosis of the lung. The objective of this study was to determine the best dose and treatment duration of BIO 300 to mitigate lung injury and improve the likelihood for survival in C57L/J mice exposed to whole thorax lung irradiation (WTLI).

EXPERIMENTAL APPROACH

Age- and sex-matched C57L/J mice received a single dose of 11.0 or 12.5 Gy WTLI. BIO 300 (200 or 400 mg·kg^-1 , oral gavage) was administered daily starting 24 h post-exposure for a duration of 2, 4, 6 or, in some cases, 10 weeks. Non-treated controls were included for comparison in both sexes. Animals were observed daily for signs of major morbidity. Respiratory function was assessed biweekly. Lungs were collected, weighed and paraffin embedded for histological evaluation post mortem.

KEY RESULTS

BIO 300 administered at an oral dose of 400 mg·kg^-1 for 4 to 6 weeks starting 24 h post-WTLI reduced morbidity associated with WTLI. The improvement in survival correlated with reduced respiratory frequency and enhanced pause. The irradiated lungs of mice treated with BIO 300 (400 mg·kg^-1 ) for 4 to 6 weeks displayed less morphological damage and airway loss due to oedema, congestion and fibrotic scarring than the untreated, irradiated controls.

CONCLUSIONS AND IMPLICATIONS

BIO 300 is a promising MCM candidate to mitigate pneumonitis/fibrosis when administered daily for 4-6 weeks starting 24 h post-exposure.

Targeted Metabolomics Identifies Pharmacodynamic Biomarkers for BIO 300 Mitigation of Radiation-Induced Lung Injury

PURPOSE

Biomarkers serve a number of purposes during drug development including defining the natural history of injury/disease, serving as a secondary endpoint or trigger for intervention, and/or aiding in the selection of an effective dose in humans. BIO 300 is a patent-protected pharmaceutical formulation of nanoparticles of synthetic genistein being developed by Humanetics Corporation. The primary goal of this metabolomic discovery experiment was to identify biomarkers that correlate with radiation-induced lung injury and BIO 300 efficacy for mitigating tissue damage based upon the primary endpoint of survival.

METHODS

High-throughput targeted metabolomics of lung tissue from male C57L/J mice exposed to 12.5 Gy whole thorax lung irradiation, treated daily with 400 mg/kg BIO 300 for either 2 weeks or 6 weeks starting 24 h post radiation exposure, were assayed at 180 d post-radiation to identify potential biomarkers.

RESULTS

A panel of lung metabolites that are responsive to radiation and able to distinguish an efficacious treatment schedule of BIO 300 from a non-efficacious treatment schedule in terms of 180 d survival were identified.

CONCLUSIONS

These metabolites represent potential biomarkers that could be further validated for use in drug development of BIO 300 and in the translation of dose from animal to human.

Full Length Interleukin 33 Aggravates Radiation-Induced Skin Reaction

The interleukin (IL)-1 family member IL-33 has been described as intracellular alarmin with broad roles in wound healing, skin inflammation but also autoimmunity. Its dichotomy between full length (fl) IL-33 and the mature (m) form of IL-33 and its release by necrosis is still not fully understood. Here, we compare functional consequences of both forms in the skin in vivo, and therefore generated two lines of transgenic mice which selectively overexpress mmIL-33 and flmIL-33 in basal keratinocytes. Transgene mRNA was expressed at high level in skin of both lines but not in organs due to the specific K14 promoter. We could demonstrate that transgenic overexpression of mmIL-33 in murine keratinocytes leads to a spontaneous skin inflammation as opposed to flmIL-33. K14-mmIL-33 mice synthesize and secrete high amounts of mmIL-33 along with massive cutaneous manifestations, like increased epidermis and dermis thickness, infiltration of mast cells in the epidermis and dermis layers and marked hyperkeratosis. Using skin inflammation models such as IL-23 administration, imiquimod treatment, or mechanical irritation did not lead to exacerbated inflammation in the K14-flmIL-33 strain. As radiation induces a strong dermatitis due to apoptosis and necrosis, we determined the effect of fractionated radiation (12 Gy, 4 times). In comparison to wild-type mice, an increase in ear thickness in flmIL-33 transgenic mice was observed 25 days after irradiation. Macroscopic examination showed more severe skin symptoms in irradiated ears compared to controls. In summary, secreted mmIL-33 itself has a potent capacity in skin inflammation whereas fl IL-33 is limited due to its intracellular retention. During tissue damage, fl IL-33 exacerbated radiation-induced skin reaction.

Pharmacological Modulation of Radiation Damage. Does It Exist a Chance for Other Substances than Hematopoietic Growth Factors and Cytokines?

In recent times, cytokines and hematopoietic growth factors have been at the center of attention for many researchers trying to establish pharmacological therapeutic procedures for the treatment of radiation accident victims. Two granulocyte colony-stimulating factor-based radiation countermeasures have been approved for the treatment of the hematopoietic acute radiation syndrome. However, at the same time, many different substances with varying effects have been tested in animal studies as potential radioprotectors and mitigators of radiation damage. A wide spectrum of these substances has been studied, comprising various immunomodulators, prostaglandins, inhibitors of prostaglandin synthesis, agonists of adenosine cell receptors, herbal extracts, flavonoids, vitamins, and others. These agents are often effective, relatively non-toxic, and cheap. This review summarizes the results of animal experiments, which show the potential for some of these untraditional or new radiation countermeasures to become a part of therapeutic procedures applicable in patients with the acute radiation syndrome. The authors consider β-glucan, 5-AED (5-androstenediol), meloxicam, γ-tocotrienol, genistein, IB-MECA (N⁶-(3-iodobezyl)adenosine-5'-N-methyluronamide), Ex-RAD (4-carboxystyryl-4-chlorobenzylsulfone), and entolimod the most promising agents, with regards to their contingent use in clinical practice.

The Role of Proinflammatory Cytokine Interleukin-18 in Radiation Injury

Massive radiation-induced inflammatory factors released from injured cells may cause innate and acquired immune reactions that can further result in stress response signal activity-induced local and systemic damage. IL-1 family members IL-1β, IL-18, and IL-33 play key roles in inflammatory and immune responses and have been recognized to have significant influences on the pathogenesis of diseases. IL-1β, IL-18, and IL-33 share similarities of cytokine biology, but differences exist in signaling pathways. A key component of the inflammatory reaction is the inflammasome, which is a caspase-1-containing multiprotein oligomer. Pathological stimuli such as radiation can induce inflammasome and caspase-1 activation, and subsequently cause maturation (activation) of pro-forms of IL-1 and IL-18 upon caspase-1 cleavage. This caspase-1 dependent and IL-1 and IL-18 associated cell damage is defined as pyroptosis. Activated IL-1 and IL-18 as proinflammatory cytokines drive pathology at different immune and inflammatory disorders through Toll-like receptor (TLR) signaling. While the mechanisms of IL-1β-induced pathophysiology of diseases have been well studied, IL-18 has received less attention. The author recently reported that gamma radiation highly increased IL-1β, IL-18 and IL-33 expression in mouse thymus, spleen and/or bone marrow cells; also circulating IL-18 can be used as a radiation biomarker to track radiation injury in mice, minipigs, and nonhuman primates. This mini-review focuses on the role of IL-18 in response to gamma radiation-induced injury.

Circulating IL-18 Binding Protein (IL-18BP) and IL-18 as Dual Biomarkers of Total-Body Irradiation in Mice

We have previously reported that circulating interleukin-18 (IL-18) can be used as a radiation biomarker in mice, minipigs and nonhuman primates. In this study, we further determined the serum levels of IL-18 binding protein (IL-18BP), a natural endogenous antagonist of IL-18, in CD2F1 mice 1-13 days after total-body gamma irradiation (TBI) with different doses (5-10 Gy). We compared the changes in blood lymphocyte, neutrophil and platelet counts as well as the activation of the proapoptotic executioner caspase-3 and caspase-7, and the expression of the inflammatory factor cyclooxygenase 2 (COX-2) in spleen cells, with the changes of IL-18BP and IL-18 in mouse serum. We also evaluated the significance, sensitivity and specificity of alterations in radiation-induced IL-18BP. IL-18 increased from day 1-13 after TBI in a dose-dependent manner that was paralleled with an increase in IL-18 receptor alpha (IL-18Rα) in irradiated mouse spleen cells. IL-18BP rapidly increased (25-63 fold) in mouse serum on day 1 after different doses of TBI. However, it returned to baseline within 3 days after 5-7 Gy doses and within 7 days after 8 Gy dose, and was unaltered thereafter. In contrast, high doses of radiation (9 and 10 Gy) significantly sustained a higher level of IL-18BP in mouse serum and later induced a second phase of increase in IL-18BP on day 9-13 after irradiation, which coincided with the onset of animal mortality. Consistent with this observation, highly activated caspase-3 and -7 in 8-10 Gy irradiated mouse spleen cells exhibited reduced or no activity 24 h after 5 Gy, although radiation induced an inflammatory response, as shown by COX-2 expression in all irradiated cells. Our data suggest that the radiation-induced differential elevation of IL-18 and IL-18BP in animal serum is a dynamic and discriminative indicator of the severity of injury after exposure to ionizing radiation. These findings support the inclusion of the dual biomarkers IL-18BP and IL-18 in the development of a multifactorial strategy for radiation dose and injury assessment.

Medical Countermeasures for Radiation Exposure and Related Injuries: Characterization of Medicines, FDA-Approval Status and Inclusion into the Strategic National Stockpile

World events over the past decade have highlighted the threat of nuclear terrorism as well as an urgent need to develop radiation countermeasures for acute radiation exposures and subsequent bodily injuries. An increased probability of radiological or nuclear incidents due to detonation of nuclear weapons by terrorists, sabotage of nuclear facilities, dispersal and exposure to radioactive materials, and accidents provides the basis for such enhanced radiation exposure risks for civilian populations. Although the search for suitable radiation countermeasures for radiation-associated injuries was initiated more than half a century ago, no safe and effective radiation countermeasure for the most severe of these injuries, namely acute radiation syndrome (ARS), has been approved by the United States Food and Drug Administration (FDA). The dearth of FDA-approved radiation countermeasures has prompted intensified research for a new generation of radiation countermeasures. In this communication, the authors have listed and reviewed the status of radiation countermeasures that are currently available for use, or those that might be used for exceptional nuclear/radiological contingencies, plus a limited few medicines that show early promise but still remain experimental in nature and unauthorized for human use by the FDA.

Delta-tocotrienol suppresses radiation-induced microRNA-30 and protects mice and human CD34+ cells from radiation injury

We reported that microRNA-30c (miR-30c) plays a key role in radiation-induced human cell damage through an apoptotic pathway. Herein we further evaluated radiation-induced miR-30 expression and mechanisms of delta-tocotrienol (DT3), a radiation countermeasure candidate, for regulating miR-30 in a mouse model and human hematopoietic CD34+ cells. CD2F1 mice were exposed to 0 (control) or 7–12.5 Gy total-body gamma-radiation, and CD34+ cells were irradiated with 0, 2 or 4 Gy of radiation. Single doses of DT3 (75 mg/kg, subcutaneous injection for mice or 2 μM for CD34+ cell culture) were administrated 24 h before irradiation and animal survival was monitored for 30 days. Mouse bone marrow (BM), jejunum, kidney, liver and serum as well as CD34+ cells were collected at 1, 4, 8, 24, 48 or 72 h after irradiation to determine apoptotic markers, pro-inflammatory cytokines interleukin (IL)-1β and IL-6, miR-30, and stress response protein expression. Our results showed that radiation-induced IL-1β release and cell damage are pathological states that lead to an early expression and secretion of miR-30b and miR-30c in mouse tissues and serum and in human CD34+ cells. DT3 suppressed IL-1β and miR-30 expression, protected against radiation-induced apoptosis in mouse and human cells, and increased survival of irradiated mice. Furthermore, an anti-IL-1β antibody downregulated radiation-induced NFκBp65 phosphorylation, inhibited miR-30 expression and protected CD34+ cells from radiation exposure. Knockdown of NFκBp65 by small interfering RNA (siRNA) significantly suppressed radiation-induced miR-30 expression in CD34+ cells. Our data suggest that DT3 protects human and mouse cells from radiation damage may through suppression of IL-1β-induced NFκB/miR-30 signaling.

New approaches to radiation protection

Radioprotectors are compounds that protect against radiation injury when given prior to radiation exposure. Mitigators can protect against radiation injury when given after exposure but before symptoms appear. Radioprotectors and mitigators can potentially improve the outcomes of radiotherapy for cancer treatment by allowing higher doses of radiation and/or reduced damage to normal tissues. Such compounds can also potentially counteract the effects of accidental exposure to radiation or deliberate exposure (e.g., nuclear reactor meltdown, dirty bomb, or nuclear bomb explosion); hence they are called radiation countermeasures. Here, we will review the general principles of radiation injury and protection and describe selected examples of radioprotectors/mitigators ranging from small-molecules to proteins to cell-based treatments. We will emphasize agents that are in more advanced stages of development.

Radiation countermeasure agents: an update (2011-2014)

INTRODUCTION

Despite significant scientific advances over the past 60 years towards the development of a safe, nontoxic and effective radiation countermeasure for the acute radiation syndrome (ARS), no drug has been approved by the US FDA. A radiation countermeasure to protect the population at large from the effects of lethal radiation exposure remains a significant unmet medical need of the US citizenry and, thus, has been recognized as a high priority area by the government.

AREA COVERED

This article reviews relevant publications and patents for recent developments and progress for potential ARS treatments in the area of radiation countermeasures. Emphasis is placed on the advanced development of existing agents since 2011 and new agents identified as radiation countermeasure for ARS during this period.

EXPERT OPINION

A number of promising radiation countermeasures are currently under development, seven of which have received US FDA investigational new drug status for clinical investigation. Four of these agents, CBLB502, Ex-RAD, HemaMax and OrbeShield, are progressing with large animal studies and clinical trials. G-CSF has high potential and well-documented therapeutic effects in countering myelosuppression and may receive full licensing approval by the US FDA in the future.

Circulating interleukin-18 as a biomarker of total-body radiation exposure in mice, minipigs, and nonhuman primates (NHP)

We aim to develop a rapid, easy-to-use, inexpensive and accurate radiation dose-assessment assay that tests easily obtained samples (e.g., blood) to triage and track radiological casualties, and to evaluate the radioprotective and therapeutic effects of radiation countermeasures. In the present study, we evaluated the interleukin (IL)-1 family of cytokines, IL-1β, IL-18 and IL-33, as well as their secondary cytokines’ expression and secretion in CD2F1 mouse bone marrow (BM), spleen, thymus and serum in response to γ-radiation from sublethal to lethal doses (5, 7, 8, 9, 10, or 12 Gy) at different time points using the enzyme-linked immune sorbent assay (ELISA), immunoblotting, and cytokine antibody array. Our data identified increases of IL-1β, IL-18, and/or IL-33 in mouse thymus, spleen and BM cells after total-body irradiation (TBI). However, levels of these cytokines varied in different tissues. Interestingly, IL-18 but not IL-1β or IL-33 increased significantly (2.5–24 fold) and stably in mouse serum from day 1 after TBI up to 13 days in a radiation dose-dependent manner. We further confirmed our finding in total-body γ-irradiated nonhuman primates (NHPs) and minipigs, and demonstrated that radiation significantly enhanced IL-18 in serum from NHPs 2–4 days post-irradiation and in minipig plasma 1–3 days post-irradiation. Finally, we compared circulating IL-18 with the well known hematological radiation biomarkers lymphocyte and neutrophil counts in blood of mouse, minipigs and NHPs and demonstrated close correlations between these biomarkers in response to radiation. Our results suggest that the elevated levels of circulating IL-18 after radiation proportionally reflect radiation dose and severity of radiation injury and may be used both as a potential biomarker for triage and also to track casualties after radiological accidents as well as for therapeutic radiation exposure.

Comments on the mechanisms of action of radiation protective agents: basis components and their polyvalence

Purpose

These comments suggest a division of radiation protective agents on the grounds of their mechanism of action that increase the radio resistance of an organism.

Conclusion

Given below is the division of radiation protective agents on the basis of their mechanism of action into 3 groups: 1) Radiation protective agents, with the implementation of radiation protective action taking place at the cellular level in the course of rapidly proceeding radiation-chemical reactions. At the same time, when the ionizing radiation energy is absorbed, these agents partially neutralize the “oxygen effect” as a radiobiological phenomenon, especially in the radiolysis of DNA; 2) Radiation protective agents that exert their effect at the system level by accelerating the post-radiation recovery of radiosensitive tissues through activation of a number of pro-inflammatory signaling pathways and an increase in the secretion of hematopoietic growth factors, including their use as mitigators in the early period after irradiation prior to the clinical development of acute radiation syndrome (ARS). 3) Radiomodulators including drugs and nutritional supplements that can elevate the resistance of the organism to adverse environmental factors, including exposure to ionization by means of modulating the gene expression through a hormetic effect of small doses of stressors and a “substrate” maintenance of adaptive changes, resulting in an increased antioxidant protection of the organism. Radiation protective agents having polyvalence in implementation of their action may simultaneously induce radioprotective effect by various routes with a prevalence of basis mechanisms of the action.

Single administration of p2TA (AB103), a CD28 antagonist peptide, prevents inflammatory and thrombotic reactions and protects against gastrointestinal injury in total-body irradiated mice

The goal of this study was to elucidate the action of the CD28 mimetic peptide p2TA (AB103) that attenuates an excessive inflammatory response in mitigating radiation-induced inflammatory injuries. BALB/c and A/J mice were divided into four groups: Control (C), Peptide (P; 5 mg/kg of p2TA peptide), Radiation (R; total body irradiation with 8 Gy γ-rays), and Radiation + Peptide (RP; irradiation followed by p2TA peptide 24 h later). Gastrointestinal tissue damage was evaluated by analysis of jejunum histopathology and immunohistochemistry for cell proliferation (Cyclin D1) and inflammation (COX-2) markers, as well as the presence of macrophages (F4/80). Pro-inflammatory cytokines IL-6 and KC as well as fibrinogen were quantified in plasma samples obtained from the same mice. Our results demonstrated that administration of p2TA peptide significantly reduced the irradiation-induced increase of IL-6 and fibrinogen in plasma 7 days after exposure. Seven days after total body irradiation with 8 Gy of gamma rays numbers of intestinal crypt cells were reduced and villi were shorter in irradiated animals compared to the controls. The p2TA peptide delivery 24 h after irradiation led to improved morphology of villi and crypts, increased Cyclin D1 expression, decreased COX-2 staining and decreased numbers of macrophages in small intestine of irradiated mice. Our study suggests that attenuation of CD28 signaling is a promising therapeutic approach for mitigation of radiation-induced tissue injury.