The Aftermath of Surviving Acute Radiation Hematopoietic Syndrome and its Mitigation.

Intensive research is underway to find new agents that can successfully mitigate the acute effects of radiation exposure. This is primarily in response to potential counterthreats of radiological terrorism and nuclear accidents but there is some hope that they might also be of value for cancer patients treated with radiation therapy. Research into mitigation countermeasures typically employs classic animal models of acute radiation syndromes (ARS) that develop after whole-body irradiation (WBI). While agents are available that successfully mitigate ARS when given after radiation exposure, their success raises questions as to whether they simply delay lethality or unmask potentially lethal radiation pathologies that may appear later in time. Life shortening is a well-known consequence of WBI in humans and experimental animals, but it is not often examined in a mitigation setting and its causes, other than cancer, are not well-defined. This is in large part because delayed effects of acute radiation exposure (DEARE) do not follow the strict time-dose phenomena associated with ARS and present as a diverse range of symptoms and pathologies with low mortality rates that can be evaluated only with the use of large cohorts of subjects, as in this study. Here, we describe chronically increased mortality rates up to 660 days in large numbers of mice given LD70/30 doses of WBI. Systemic myeloid cell activation after WBI persists in some mice and is associated with late immunophenotypic changes and hematopoietic imbalance. Histopathological changes are largely of a chronic inflammatory nature and variable incidence, as are the clinical symptoms, including late diarrhea that correlates temporally with changes in the content of the microbiome. We also describe the acute and long-term consequences of mitigating hematopoietic ARS (H-ARS) lethality after LD70/30 doses of WBI in multiple cohorts of mice treated uniformly with radiation mitigators that have a common 4-nitro-phenylsulfonamide (NPS) pharmacophore. Effective NPS mitigators dramatically decrease ARS mortality. There is slightly increased subacute mortality, but the rate of late mortalities is slowed, allowing some mice to live a normal life span, which is not the case for WBI controls. The study has broad relevance to radiation late effects and their potential mitigation and epitomizes the complex interaction between radiation-damaged tissues and immune homeostasis.

Neulasta Regimen for the Hematopoietic Acute Radiation Syndrome: Effects Beyond Neutrophil Recovery.

PURPOSE: Understanding the physiopathology underlying the acute radiation syndrome (ARS) and the mechanism of action of drugs known to ameliorate ARS is expected to help identify novel countermeasure candidates and improve the outcome for victims exposed to radiation. Granulocyte colony-stimulating factor (G-CSF) has been approved by the US Food and Drug Administration for treatment of hematopoietic ARS (H-ARS) because of its ability to alleviate myelosuppression. Besides its role in hematopoiesis, G-CSF is known to protect the cardiovascular and neurologic systems, to attenuate vascular injury and cardiac toxicity, to preserve gap junction function, and to modulate inflammation and oxidative stress. Here, we characterized the protective effects of G-CSF beyond neutrophil recovery in minipigs exposed to H-ARS doses. METHODS AND MATERIALS: Twenty male Göttingen minipigs were exposed to total body, acute ionizing radiation. Animals received either pegylated G-CSF (Neulasta) or dextrose at days 1 and 8 after irradiation. Survival was monitored over a 45-day period. RESULTS: Neulasta decreased mortality compared with the control, reduced nadir and duration of neutropenia, and lowered prevalence of organ hemorrhage and frank bleeding episodes. Neulasta also increased plasma concentration of IGF-1 hormone, activated the cardiovascular protective IGF-1R/PI3K/Akt/eNOS/NO pathway, and enhanced membrane expression of VE-cadherin in the heart, improving vascular tone and barrier function. Expression of the acute phase protein CRP, a mediator of cardiovascular diseases and a negative regulator of the IGF-1 pathway, was also induced but at much lower extent compared with IGF-1. Activity of catalase and superoxide dismutase (SOD-1) was only marginally affected, whereas activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase was downregulated. CONCLUSIONS: In addition to a neutrophilic effect, amelioration of endothelial homeostasis and barrier function and reduction in NADPH oxidase contribute to the beneficial effects of Neulasta for the treatment of H-ARS.

MMP Inhibitor Ilomastat Improves Survival of Mice Exposed to γ-Irradiation.

There is still a need for better protection against or mitigation of the effects of ionizing radiation following conventional radiotherapy or accidental exposure. The objective of our current study was to investigate the possible roles of matrix metalloproteinase inhibitor, ilomastat, in the protection of mice from total body radiation (TBI), and the underlying protective mechanisms. Ilomastat treatment increased the survival of mice after TBI. Ilomastat pretreatment promoted recovery of hematological and immunological cells in mice after 6 Gy γ-ray TBI. Our findings suggest the potential of ilomastat to protect against or mitigate the effects of radiation.

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.

Notch-Expanded Murine Hematopoietic Stem and Progenitor Cells Mitigate Death from Lethal Radiation and Convey Immune Tolerance in Mismatched Recipients.

The hematopoietic syndrome of acute radiation syndrome (h-ARS) is characterized by severe bone marrow aplasia, resulting in a significant risk for bleeding, infections, and death. To date, clinical management of h-ARS is limited to supportive care dictated by the level of radiation exposure, with a high incidence of mortality in those exposed to high radiation doses. The ideal therapeutic agent would be an immediately available, easily distributable single-agent therapy capable of rapid in vivo hematopoietic reconstitution until recovery of autologous hematopoiesis occurs. Using a murine model of h-ARS, we herein demonstrate that infusion of ex vivo expanded murine hematopoietic stem and progenitor cells (HSPCs) into major histocompatibility complex mismatched recipient mice exposed to a lethal dose of ionizing radiation (IR) led to rapid myeloid recovery and improved survival. Survival benefit was significant in a dose-dependent manner even when infusion of the expanded cell therapy was delayed 3 days after lethal IR exposure. Most surviving mice (80%) demonstrated long-term in vivo persistence of donor T cells at low levels, and none had evidence of graft versus host disease. Furthermore, survival of donor-derived skin grafts was significantly prolonged in recipients rescued from h-ARS by infusion of the mismatched expanded cell product. These findings provide evidence that ex vivo expanded mismatched HSPCs can provide rapid, high-level hematopoietic reconstitution, mitigate IR-induced mortality, and convey donor-specific immune tolerance in a murine h-ARS model. Stem Cells Translational Medicine 2017;6:566-575.

Comparing the Hematopoetic Syndrome Time Course in the NHP Animal Model to Radiation Accident Cases From the Database Search.

Since controlled clinical studies on drug administration for the acute radiation syndrome are lacking, clinical data of human radiation accident victims as well as experimental animal models are the main sources of information. This leads to the question of how to compare and link clinical observations collected after human radiation accidents with experimental observations in non-human primate (NHP) models. Using the example of granulocyte counts in the peripheral blood following radiation exposure, approaches for adaptation between NHP and patient databases on data comparison and transformation are introduced. As a substitute for studying the effects of administration of granulocyte-colony stimulating factor (G-CSF) in human clinical trials, the method of mathematical modeling is suggested using the example of G-CSF administration to NHP after total body irradiation.

Role of radiosensitivity and radioresistance genetic markers in hematological and cardiovascular disease in persons exposed after the Chornobyl accident.

UNLABELLED: The objective was to study the immunogenetic component contribution to the formation of post-radiation effects in the long-term period after radiation exposure at the level of the human immune response as a prognostic criterion for risk assessment of radiation-associated somatic diseases. Study object was the convalescents of acute radiation syndrome (ARS) of the first grade of severity, 88 patients with a similar radiation history but with unconfirmed ARS, 73 patients being the liquidators of the Chornobyl accident consequences (LCAC) with chronic ischemic heart disease (HIHD), 65 patients LCAC without HIHD, 120 non-exposed patients with HIHD, 256 patients with oncohematological diseases and 500 healthy people - a population control. RESULTS: Markers of risk of realization of genetic predisposition to oncohematological and cardiovascular disease in these groups were identified on the basis of study of immunological, hematological and molecular genetic disorders in relation to immunogenetic factors. CONCLUSION: These data indicate that realization of HLA-genetic predisposition to the disease is one of the radiation associated multifactorial pathology pathways, and presence of radiosensitivity markers in pheno/genotype enhances the realization risk of pathological process under irradiation.

Analysis of minocycline as a countermeasure against acute radiation syndrome.

BACKGROUND/AIM: To evaluate the impact of an antibiotic, minocycline, on several immune parameters in response to radiation in a mouse model. MATERIALS AND METHODS: C57BL/6 mice were treated with minocycline (i.p.) for 5 days, beginning immediately before radiation with 1-3 Gy (60)Co γ-rays. Spleen and blood were collected on day 4 post-irradiation. Cell populations were determined in the blood and spleen. Splenocytes were activated with anti-CD3 antibody for 48 h and cytokines were quantified. RESULTS: Minocycline increased the counts and/or percentages of splenic macrophages, granulocytes, natural killer, T- and CD8(+) T-cells (p<0.05 versus radiation alone). Minocycline significantly increased the expression of interleukin-1α and ß, which are radioprotective, as well as the ones of granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor, which accelerate neutrophil recovery (p<0.05 versus radiation alone), while suppressing cytokines that could prevent hematopoiesis, e.g. macrophage inflammatory protein-1α, tumor necrosis factor-α and interferon-γ. CONCLUSION: These data indicate that minocycline should be further tested for use in restoration of the hematopoietic system after radiation exposure.

[Clinical and experimental parallels between immunological observations of irradiated animals and patients injured during Chernobyl accident].

Immunological parameters in different periods of acute radiation syndrome (ARS) of experimental animals and Chernobyl reactor accident-injured patients have been studied. 148 patients and experimental animals (123 dogs and 198 monkeys) were observed after radiation exposure of different levels (from a sub-lethal dose to the minimal absolute lethal dose). We have found the increase in the C-reactive protein, fluctuation of normal antibody titers and the complement in blood serum, as well as the growing number of skin microbes after exposures to lethal doses. Experimental results match clinical data in terms of ARS progress phases but differ from the latter in terms of the time of clinical manifestations. The highest rate of clinical manifestations is observed on the 7-14 days for experimental animals (rats, dogs and monkeys) and on the 20-30 days for patients after radiation exposure. Regenerative processes in animals run faster than those in humans.

Persistent infections and their relationship with selected oncologic and non-tumor pathologies.

Our earlier studies of hepatitis C virus (HCV) infection rates among blood donors at the Kyiv Municipal Blood Center revealed a 3.45% HCV+ prevalence in these "healthy" hosts. In the study here, we analyzed HCV (as well as cytomegalovirus [CMV]) prevalence among Chernobyl nuclear power plant (NPP) accident sufferers--cleanup workers, local residents, NPP workers, and convalescent patients--who suffered acute radiation syndrome (ARS) as a result of the 1986 accident, and individuals who had not been exposed to ionizing radiation (IR). Serological analyses of antibodies against each pathogen (via enzyme-linked immunosorbent assay [ELISA]) revealed the highest HCV (i.e., 27.2%) and CMV (85.6%) prevalence in the convalescent hosts. Though the HCV prevalence (reflecting a current/past infection) among the cleanup workers (and other groups) was lower (i.e., 11-25%), viral presence was "associated" with a higher incidence of selected somatic diseases, for example, thyroiditis, goiter, hypertension, Type 1 diabetes, chronic hepatitis/gastritis, in the cleanup workers. A similar scenario with respect to CMV was also seen, i.e., lower prevalence rates [relative to in ARS patients] and "association" between CMV status and incidence of chronic gastritis, arthritis, and bronchitis, in the cleanup workers and IR-non-exposed controls. Further, irrespective of CMV status, there was a clear delineation between incidence rate(s) of each of the pathologies and whether or not the person was/was not exposed in 1986. We also investigated, due to a high incidence of chronic lymphocytic leukemia (CLL) among Chernobyl sufferers, if there was homology between immunoglobulins (Igs) generated by these transformed cells and known antiviral and antimicrobial Igs. Polymerase chain reaction (PCR) analyses of Ig heavy-chain variable (IgHV) genes in cells from CLL patients who were/were not exposed in 1986 revealed a significant homology of some IgHV genes with Igs directed against infectious agents. However, no differences were found between the sequences from IR-exposed and IR-non-exposed CLL patients. Based on the findings here, we conclude that a past/ongoing presence of certain viral infections (i.e., CMV and/or HCV) in a host can modify (aggravate) the clinical course of certain somatic (i.e., non-tumor) diseases and promote malignancies (i.e., CLL), and that each of these outcomes could be modulated as a result of that host's past exposure to IR.

Amifostine ameliorates recognition memory defect in acute radiation syndrome caused by relatively low-dose of gamma radiation.

This study examined whether amifostine (WR-2721) could attenuate memory impairment and suppress hippocampal neurogenesis in adult mice with the relatively low-dose exposure of acute radiation syndrome (ARS). These were assessed using object recognition memory test, the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay, and immunohistochemical markers of neurogenesis [Ki-67 and doublecortin (DCX)]. Amifostine treatment (214 mg/kg, i.p.) prior to irradiation significantly attenuated the recognition memory defect in ARS, and markedly blocked the apoptotic death and decrease of Ki-67- and DCX-positive cells in ARS. Therefore, amifostine may attenuate recognition memory defect in a relatively low-dose exposure of ARS in adult mice, possibly by inhibiting a detrimental effect of irradiation on hippocampal neurogenesis.

[Study of frequency of TCR-mutant T-helper lymphocytes and level of immunocompetent cells with mFasL apoptosis marker under conditions of ionizing radiation].

Were investigated the parameters of apoptosis of immune cells, the cell subpopulation composition and frequency of TCR-mutant lymphocytes in the peripheral blood of persons exposed to radiation. Increased number of peripheral mFasL-positive mononuclear cells and the accumulation of TCR-mutant T lymphocytes in a wide range of doses were found in the patients. It is doubtless that the effect of ionizing radiation is accompanied by a simulation of Fas-ligand expression on the surface of peripheral mononuclear cells and modification of the activating signal to apoptosis through the molecule CD4, CD8, CD3. The results can be caused by proapoptotic effect of radiation.

[Recombinant human interleukine-1beta (betaleukine) usage for acute radiation sickness of severe degree treatment at canines].

Recombinant human interleukine-1beta (betaleukune) of Institute of especially pure biopreparation production had been examined as a treatment means at acute radiation disease of severe degree at dogs. Dogs were irradiated totally in doses above the LD95/45. Betaleukine had been administered s/c twice in day in 15 min - 2 h after irradiation. All the dogs, including control ones, received in acute period 8-24/26 days after irradiation antibiotics ampicillin and gentamycin i/m. Betaleukine increased 45 day-survival by 37% at 4 Gy and by 25% at 4.4 Gy. The effect correlated with more high level of nadir and more early beginning the leucocyte number restoration. We observed the regularity at all the dogs that received betaleukine as survived as died, but in the latter case in a lesser degree certainly. Besides the noticed character of leucocytes kinetics had been repeated at all the blood cell types but in the different degree. It had been concluded on the base of these observations that betaleukine acts on hemopoietic stem cells preferentially. The effect is in preventing death of a stem cells part, or in stimulating survived stem cells proliferation, or in both together. Betaleukin can be regarded as a suitable means of urgent pathogenic therapy at radiation accidents.

[The characteristic of radioprotective properties of a radioprotectant B-190 at its administration after radiation].

In experiences on mice F1 (CBAxC57B 1/6) at a gamma-irradiation in a lethal dose LD(35-70/30) the radioprotectant B-190 at administration after an exposure would rise an animal survival--on 35-55%, caused the increase of the amount of endogenic colony in a spleen and of leucocytes in blood on 11th and 30th day of an acute radiation desease accordingly. The drug has the effect in the interval of doses from 75 up to 150 mg/kg b.w. with the rise of radioprotective action on dose reduction factor from 1.1 up to 1.22. alpha(1)-adrenoblockers terasosin in a dose of 15 mg/kg b.w. partially would reduce radioprotective properties of B-190 as radioprotectant or and drug of early therapy of acute radiation desease.