Radioprotective effects of oral 17-dimethylaminoethylamino-17-demethoxygeldanamycin in mice: bone marrow and small intestine

AP2a-Mediated Upregulation of miR-125a-5p Ameliorates Radiation-Induced Oxidative Stress Injury via BRD4/Nrf2/HO-1 Signaling

Radiation therapy is widely used to restrain tumor progression, but it is always accompanied by damage to healthy tissues. We aimed to probe the impact and mechanism of activator protein 2a (AP2a) and miR-125a-5p in radiation-induced oxidative stress injury. Human umbilical vein endothelial cells (HUVECs) were treated with X rays to induce radiation injury in vitro. Cell viability was measured using MTT assays. Flow cytometry assay was employed to detect the apoptosis rate. Oxidative stress markers were evaluated by detection kits. Gene or protein levels were determined by RT-qPCR or Western blotting. Validation of the interaction of miR-125a-5p with BRD4 and AP2a was conducted by dual luciferase assay or ChIP. MiR-125a-5p and AP2a were decreased in irradiated HUVECs, whereas BRD4 was increased. MiR-125a-5p overexpression or BRD4 silencing alleviated the cell viability decline, apoptosis, and oxidative stress injury caused by radiation treatment. MiR-125a-5p repressed the BRD4 level. The protective effects of miR-125a-5p overexpression in the radiation-induced oxidative injury were impeded by BRD4 overexpression. Moreover, AP2a bound to the promoter of miR-125a-5p. MiR-125a-5p inhibition reversed the effects of AP2a overexpression on radiational oxidative injury by modulating Nrf2/HO-1 signaling. AP2a transcriptionally activated miR-125a-5p ameliorated oxidative stress injury of HUVECs caused by radiation through Nrf2/HO-1 signaling.

Histopathological Evaluation of Protective Effect of Telmisartan against Radiation-Induced Bone Marrow Injury

BACKGROUND

Radiation-induced hematopoietic suppression and myelotoxicity can occur due to the nuclear accidents, occupational irradiation and therapeutic interventions. Bone marrow dysfunction has always been one of the most important causes of morbidity and mortality after ionizing irradiation.

OBJECTIVE

This study aims to investigate the protective effect of telmisartan against radiation-induced bone marrow injuries in a Balb/c mouse model.

MATERIAL AND METHODS

In this experimental study, male Balb/c mice were divided into four groups as follow: group 1: mice received phosphate buffered saline (PBS) without irradiation, group 2: mice received a solution of telmisartan in PBS without irradiation, group 3: mice received PBS with irradiation, and group 4: mice received a solution of telmisartan in PBS with irradiation. A solution of telmisartan was prepared and administered orally at 12 mg/kg body weight for seven consecutive days prior to whole body exposing to a single sub-lethal dose of 5 Gy X-rays. Protection of bone marrow against radiation induced damage was investigated by Hematoxylin-Eosin (HE) staining assay at 3, 9, 15 and 30 days after irradiation.

RESULTS

Histopathological analysis indicated that administration of telmisartan reduced X-radiation-induced damage and improved bone marrow histology. The number of different cell types in bone marrow, including polymorphonuclear /mononuclear cells and megakaryocytes significantly increased in telmisartan treated group compared to the only irradiated group at all-time points.

CONCLUSION

The results of the present study demonstrated an efficient radioprotective effect of telmisartan in mouse bone marrow against sub-lethal X-irradiation.

Therapeutic implications of exosomes in the treatment of radiation injury

Radiotherapy is one of the main cancer treatments, but it may damage normal tissue and cause various side effects. At present, radioprotective agents used in clinics have side effects such as nausea, vomiting, diarrhea and hypotension, which limit their clinical application. It has been found that exosomes play an indispensable role in radiation injury. Exosomes are lipid bilayer vesicles that carry various bioactive substances, such as proteins, lipids and microRNA (miRNA), that play a key role in cell-to-cell communication and affect tissue injury and repair. In addition, studies have shown that radiation can increase the uptake of exosomes in cells and affect the composition and secretion of exosomes. Here, we review the existing studies and discuss the effects of radiation on exosomes and the role of exosomes in radiation injury, aiming to provide new insights for the treatment of radiation injury.

Rapamycin-mediated mouse lifespan extension: Late-life dosage regimes with sex-specific effects

To see if variations in timing of rapamycin (Rapa), administered to middle aged mice starting at 20 months, would lead to different survival outcomes, we compared three dosing regimens. Initiation of Rapa at 42 ppm increased survival significantly in both male and female mice. Exposure to Rapa for a 3‐month period led to significant longevity benefit in males only. Protocols in which each month of Rapa treatment was followed by a month without Rapa exposure were also effective in both sexes, though this approach was less effective than continuous exposure in female mice. Interpretation of these results is made more complicated by unanticipated variation in patterns of weight gain, prior to the initiation of the Rapa treatment, presumably due to the use of drug‐free food from two different suppliers. The experimental design included tests of four other drugs, minocycline, β‐guanidinopropionic acid, MitoQ, and 17‐dimethylaminoethylamino‐17‐demethoxygeldanamycin (17‐DMAG), but none of these led to a change in survival in either sex.

Radiotherapy Induces Intestinal Barrier Dysfunction by Inhibiting Autophagy

Radiation enteritis is a common complication of abdominal irradiation (IR) therapy. However, the molecular mechanism of radiation enteritis accompanied by impaired intestinal barrier function is not clear. The aim of this study was to investigate the important role of autophagy in radiation-induced intestinal barrier function impairment. IR increased the abundance of autophagy-related genes in the colonic mucosa of mice. An autophagy activator (rapamycin) inhibited the oxidative stress (reactive oxygen species, reactive nitrogen species, malondialdehyde, and hydrogen peroxide) and inflammatory response (interleukin-1β, -6, -8, and tumor necrosis factor-α) in the colon samples. Antioxidant indices (superoxide dismutase, glutathione peroxidase, catalase, and total antioxidant capacity) in serum and colonic mucosa were significantly increased in the rapamycin group. Rapamycin can improve the activity of mitochondrial respiratory chain complexes I-V in colon mucosa. In addition, rapamycin reduced the gene expression and enzyme activity of caspase in the colonic mucosa. Levels of endotoxin, diamine peroxidase, d-lactic acid, and zonulin in serum and colonic mucosa were significantly reduced in the rapamycin group. Moreover, rapamycin significantly elevated the gene abundance of zonula occludens-1, occludin, claudin-1, and claudin-4. In contrast, completely opposite results were obtained for the autophagy inhibitor 3-methyladenine as compared to those of rapamycin. These results revealed that inhibition of autophagy is an important mechanism of intestinal barrier function damage caused by radiation. Collectively, these findings increase our understanding of the pathogenesis of radiation-induced intestinal barrier dysfunction.

Arabinoxylan rice bran (MGN-3/Biobran) alleviates radiation-induced intestinal barrier dysfunction of mice in a mitochondrion-dependent manner

MGN-3 is an arabinoxylan from rice bran that has been shown to be an excellent antioxidant and radioprotector. This study examined the protective effects of MGN-3 on radiation-induced intestinal injury. Mice were treated with MGN-3 prior to irradiation, then continued to receive MGN-3 for 4 weeks thereafter. MGN-3 increased the activity of mitochondrial respiratory chain complexes Ⅰ, Ⅲ, Ⅳ and Ⅴ, the intercellular ATP content, the mitochondria-encoded gene expression and mitochondrial copy numbers in the jejunal and colonic mucosa. MGN-3 reduced the oxidative stress levels and inflammatory response indicators in the serum and jejunal and colonic mucosa. Antioxidant indicators such as superoxide dismutase, glutathione peroxidase, catalase and total antioxidant capacity were significantly increased in the serum and jejunal and colonic mucosa in the MGN-3 group. Moreover, MGN-3 decreased the gene abundances and enzymatic activities of caspase-3, 8, 9 and 10 in the jejunal and colonic mucosa. The endotoxin, diamine peroxidase, d-lactate and zonulin levels were significantly reduced in the serum and jejunal and colonic mucosa in the MGN-3 group. MGN-3 also markedly upregulated the gene abundances of ZO-1, occludin, claudin-1 and mucin 2. MGN-3 effectively attenuated radiation-induced changes in the intestinal epithelial mitochondrial function, oxidative stress, inflammatory response, apoptosis, intestinal permeability and barrier function in mice. These findings add to our understanding of the potential mechanisms by which MGN-3 alleviates radioactive intestinal injury.

Radioprotective Effect of Walnut Oligopeptides Against Gamma Radiation-Induced Splenocyte Apoptosis and Intestinal Injury in Mice

Walnut oligopeptides (WOPs) intake is associated with the augment of the antioxidant defense system and immune system. The chief object of this study is to evaluate the radioprotective effect of walnut oligopeptides extracted from walnut seed protein against ⁶⁰Coγ-irradiation induced damage in mice. Female BALB/c mice were administered WOPs through drinking water for 14 days until a single dose of whole-body ⁶⁰Coγ-irradiation. The 30-day survival test was carried out in the first group (8 Gy), and the other two groups (3.5 Gy) were sacrificed at 3 days and 14 days post-irradiation. Blood and organ samples of mice in the three groups were collected, the histopathological analysis and immunohistochemistry were conducted. The number of peripheral blood leukocytes, bone marrow DNA content, inflammatory cytokines, antioxidant capacity, and intestinal permeability were measured. We found that the administration of WOPs augmented antioxidant defense system, accelerated hematopoietic recovery and showed the significant trend toward higher survival rate and less weight loss compared with non-administrated control mice. In addition, WOPs administration appeared to be important to limit IR-induced splenocyte apoptosis and inflammatory cascade as well as reduce intestine epithelial barrier dysfunction and promote epithelial integrity. These results suggest that pre and post-treatment of WOPs may help to ameliorate acute damage, which is induced by ionizing radiation in mice and accelerate its recovery.

Characterization and Etiology of Swollen Muzzles in Irradiated Mice

Several investigators performing bone marrow transplantation studies have previously reported sporadic increases in mortality that were associated with pronounced swelling in the face, head and neck of mice. Over the past few years, we and others have noted an increasing number of experiments in which mice that have received total-body irradiation (TBI) or partial-body irradiation (PBI) develop swollen muzzles, drastic thickening of the upper lip and redness, bruising and/or swelling around the nose and muzzle and sometimes over the top of the head. We refer to this rapid and extreme swelling after irradiation as swollen muzzle syndrome (SMS). The development of SMS postirradiation is associated with morbidity that occurs earlier than would be expected from the traditional hematopoietic acute radiation syndrome (H-ARS), and has impeded studies in several laboratories attempting to evaluate medical countermeasures (MCM) against radiation. However, little has been done to characterize this somewhat unpredictable radiation effect. To investigate the cause and etiology of SMS, data from three different laboratories collected over a seven-year period from 100 MCM 30-day survival studies using mice from different vendors were retrospectively analyzed to determine the time of onset, progression and incidence of SMS in male and female mice exposed to various doses of ionizing radiation. An additional study compared incidence and etiology of SMS in mice from two different vendors (identified as vendors A and B) after exposure to the LD_50/30 (X rays). Mice presenting with SMS, as well as non-SMS (irradiated) control mice, were necropsied to determine microbial status of the blood, heart, spleen, liver, kidney and muzzle tissue. Only mice from vendor A (20%) developed SMS. While the number of bacterial species isolated from various tissues of SMS and non-SMS mice was not different, the number of tissues positive for bacteria was significantly greater in SMS mice. At least one tissue in 83% of SMS mice from vendor A tested positive for Streptococcus agalactiae [group B beta Streptococcus (GBS)], compared to 25% of non-SMS mice from vendor A, and 0% of non-SMS mice from vendor B. In addition, all mice from vendor A with SMS had at least one tissue with >10⁴ CFU/g, with GBS as the predominant bacterium, compared to only 25% of non-SMS mice from vendor A, and 0% of non-SMS mice from vendor B. The incidence and magnitude of GBS growth in cultures correlated with the onset of SMS; the earliest and heaviest infections occurred in mice presenting with SMS on days 5-6 postirradiation. The majority of SMS mice (5 out of 6) had positive blood cultures, with the same bacterial strain isolated from other tissues, suggesting systemic translocation via the bloodstream. We propose that testing of mice and the identification of the microorganisms frequently associated with SMS may provide guidance for selection of antimicrobials for use by other investigators in studies evaluating potential MCM, and for the ordering, handling and care of immunodeficient mice or mice that are to be rendered immunodeficient after acute irradiation.

Kaempferol protects against gamma radiation-induced mortality and damage via inhibiting oxidative stress and modulating apoptotic molecules in vivo and vitro

To investigate the potential protective effect of kaempferol, a representative flavonoid, against radiation induced mortality and injury in vivo and vitro.C57BL/6 male mice and human umbilical venous endothelial cells (HUVECs) were pretreated with kaempferol before radiation. We found that kaempferol can effectively increase 30-day survival rate after 8.5 Gy lethal total body irradiation (TBI). Mice were sacrificed at 7th day after 7 Gy TBI, we found kaempferol against radiation-induced tissues damage, by inhibiting the oxidative stress, and attenuating morphological changes and cell apoptosis. In vitro, kaempferol increased HUVECs cell viability and decrease apoptosis. It also mitigated oxidative stress and restored the abnormal expression of prx-5, Cyt-c, Caspase9 and Caspase3 in mRNA and protein level in HUVECs after radiation. Taken together, it suggests kaempferol can protect against gamma-radiation induced tissue damage and mortality. The present study is the first report of the radioprotective role of kaempferol in vivo and vitro.

Hemorrhage enhances cytokine, complement component 3, and caspase-3, and regulates microRNAs associated with intestinal damage after whole-body gamma-irradiation in combined injury

Hemorrhage following whole-body γ-irradiation in a combined injury (CI) model increases mortality compared to whole-body γ-irradiation alone (RI). The decreased survival in CI is accompanied by increased bone marrow injury, decreased hematocrit, and alterations of miRNA in the kidney. In this study, our aim was to examine cytokine homeostasis, susceptibility to systemic bacterial infection, and intestinal injury. More specifically, we evaluated the interleukin-6 (IL-6)-induced stress proteins including C-reactive protein (CRP), complement 3 (C3), Flt-3 ligand, and corticosterone. CD2F1 male mice received 8.75 Gy 60Co gamma photons (0.6 Gy/min, bilateral) which was followed by a hemorrhage of 20% of the blood volume. In serum, RI caused an increase of IL-1, IL-2, IL-3, IL-5, IL-6, IL-12, IL-13, IL-15, IL-17A, IL-18, G-CSF, CM-CSF, eotaxin, IFN-γ, MCP-1, MIP, RANTES, and TNF-α, which were all increased by hemorrhage alone, except IL-9, IL-17A, and MCP-1. Nevertheless, CI further elevated RI-induced increases of these cytokines except for G-CSF, IFN- γ and RANTES in serum. In the ileum, hemorrhage in the CI model significantly enhanced RI-induced IL-1β, IL-3, IL-6, IL-10, IL-12p70, IL-13, IL-18, and TNF-α concentrations. In addition, Proteus mirabilis Gram(-) was found in only 1 of 6 surviving RI mice on Day 15, whereas Streptococcus sanguinis Gram(+) and Sphingomonas paucimobilis Gram(-) were detected in 2 of 3 surviving CI mice (with 3 CI mice diseased due to inflammation and infection before day 15) at the same time point. Hemorrhage in the CI model enhanced the RI-induced increases in C3 and decreases in CRP concentrations. However, hemorrhage alone did not alter the basal levels, but hemorrhage in the CI model displayed similar increases in Flt-3 ligand levels as RI did. Hemorrhage alone altered the basal levels of corticosterone early after injury, which then returned to the baseline, but in RI mice and CI mice the increased corticosterone concentration remained elevated throughout the 15 day study. CI increased 8 miRNAs and decreased 10 miRNAs in serum, and increased 16 miRNA and decreased 6 miRNAs in ileum tissue. Among the altered miRNAs, CI increased miR-34 in the serum and ileum which targeted an increased phosphorylation of ERK, p38, and increased NF-κB, thereby leading to increased iNOS expression and activation of caspase-3 in the ileum. Further, let-7g/miR-98 targeted the increased phosphorylation of STAT3 in the ileum, which is known to bind to the iNOS gene. These changes may correlate with cell death in the ileum of CI mice. The histopathology displayed blunted villi and villus edema in RI and CI mice. Based on the in silico analysis, miR-15, miR-99, and miR-100 were predicted to regulate IL-6 and TNF. These results suggest that CI-induced alterations of cytokines/chemokines, CRP, and C3 cause a homeostatic imbalance and may contribute to the pathophysiology of the gastrointestinal injury. Inhibitory intervention in these responses may prove therapeutic for CI and improve recovery of the ileal morphologic damage.

A review of radiation countermeasures focusing on injury-specific medicinals and regulatory approval status: part III. Countermeasures under early stages of development along with 'standard of care' medicinal and procedures not requiring regulatory approval for use

PURPOSE

Terrorist attacks, with their intent to maximize psychological and economic damage as well as inflicting sickness and death on given targeted populations, are an ever-growing worldwide concern in government and public sectors as they become more frequent, violent, and sensational. If given the chance, it is likely that terrorists will use radiological or nuclear weapons. To thwart these sinister efforts, both physical and medical countermeasures against these weapons are currently being researched and developed so that they can be utilized by the first responders, military, and medical providers alike. This is the third article of a three-part series in which we have reviewed additional radiation countermeasures that are currently under early preclinical phases of development using largely animal models and have listed and discussed clinical support measures, including agents used for radiation-induced emesis, as well as countermeasures not requiring Food and Drug Administration approval.

CONCLUSIONS

Despite the significant progress that has been made in this area during the last several years, additional effort is needed in order to push promising new agents, currently under development, through the regulatory pipeline. This pipeline for new promising drugs appears to be unreasonably slow and cumbersome; possible reasons for this inefficiency are briefly discussed. Significant and continued effort needs to be afforded to this research and development area, as to date, there is no approved radioprotector that can be administered prior to high dose radiation exposure. This represents a very significant, unmet medical need and a significant security issue. A large number of agents with potential to interact with different biological targets are under development. In the next few years, several additional radiation countermeasures will likely receive Food and Drug Administration approval, increasing treatment options for victims exposed to unwanted ionizing irradiation.

Data on the radioprotective effect of emodin in vivo and vitro via inhibition of apoptosis and modulation of p53

This paper contains the experiment data on the emodin, mice and cell survival rate, mice intestinal tissue H&E and TUNEL staining, the expression of p53 protein in mice small intestine, cell apoptosis, the expression of protein and RNA in vitro included. Data was worked out through MTT assay, Flow cytometry, Western blot, Real-time PCR and Staining.

A Combination of Podophyllotoxin and Rutin Attenuates Radiation Induced Gastrointestinal Injury by Negatively Regulating NF-κB/p53 Signaling in Lethally Irradiated Mice

Development of an effective radio protector to minimise radiation-inflicted damages have largely failed owing to inherent toxicity of most of the agents examined so far. This study is centred towards delivering protection to lethally irradiated mice by pre-administration of a safe formulation G-003M (combination of podophyllotoxin and rutin) majorly through regulation of inflammatory and cell death pathways in mice. Single intramuscular dose of G-003M injected 60 min prior to 9 Gy exposure rescued 89% of whole body lethally irradiated C57BL/6J mice. Studies have revealed reduction in radiation induced reactive oxygen species (ROS), nitric oxide (NO) generation, prostaglandin E2 (PGE2) levels and intestinal apoptosis in G-003M pre-treated mice intestine. Restricted nuclear translocation of redox-sensitive Nuclear factor-κB (NF-κB) and subsequent downregulation of cyclo-oxygenase 2 (COX-2), inducible nitric oxide synthase (iNOS; EC 1.14.13.39) and tumor necrosis factor (TNF-α) levels demonstrated the anti-inflammatory effect that G-003M exerts. Support to early hematopoietic recovery was exhibited through G-003M mediated induction of granulocyte colony stimulating factor (G-CSF) and interleukin (IL-6) levels in lethally irradiated mice. Considerable attenuation in radiation induced morphological damage to the intestinal villi, crypts and mucosal layers was observed in G-003M pre-treated mice. Additionally, our formulation did not reduce the sensitivity of tumor tissue to radiation. Altogether, these results suggest that G-003M ameliorates the deleterious effects of radiation exposure by minimising ROS and NO generation and effectively regulating inflammatory and cell death pathways. Mechanism of protection elucidated in the current study demonstrates that G-003M can be used as a safe and effective radio protective agent in radiotherapy for human application.

MDP: A Deinococcus Mn2+-Decapeptide Complex Protects Mice from Ionizing Radiation

The radioprotective capacity of a rationally-designed Mn²⁺-decapeptide complex (MDP), based on Mn antioxidants in the bacterium Deinococcus radiodurans, was investigated in a mouse model of radiation injury. MDP was previously reported to be extraordinarily radioprotective of proteins in the setting of vaccine development. The peptide-component (DEHGTAVMLK) of MDP applied here was selected from a group of synthetic peptides screened in vitro for their ability to protect cultured human cells and purified enzymes from extreme damage caused by ionizing radiation (IR). We show that the peptides accumulated in Jurkat T-cells and protected them from 100 Gy. MDP preserved the activity of T4 DNA ligase exposed to 60,000 Gy. In vivo, MDP was nontoxic and protected B6D2F1/J (female) mice from acute radiation syndrome. All irradiated mice treated with MDP survived exposure to 9.5 Gy (LD_70/30) in comparison to the untreated mice, which displayed 63% lethality after 30 days. Our results show that MDP provides early protection of white blood cells, and attenuates IR-induced damage to bone marrow and hematopoietic stem cells via G-CSF and GM-CSF modulation. Moreover, MDP mediated the immunomodulation of several cytokine concentrations in serum including G-CSF, GM-CSF, IL-3 and IL-10 during early recovery. Our results present the necessary prelude for future efforts towards clinical application of MDP as a promising IR countermeasure. Further investigation of MDP as a pre-exposure prophylactic and post-exposure therapeutic in radiotherapy and radiation emergencies is warranted.

Radioprotective Agents: Strategies and Translational Advances

Radioprotectors are agents required to protect biological system exposed to radiation, either naturally or through radiation leakage, and they protect normal cells from radiation injury in cancer patients undergoing radiotherapy. It is imperative to study radioprotectors and their mechanism of action comprehensively, looking at their potential therapeutic applications. This review intimately chronicles the rich intellectual, pharmacological story of natural and synthetic radioprotectors. A continuous effort is going on by researchers to develop clinically promising radioprotective agents. In this article, for the first time we have discussed the impact of radioprotectors on different signaling pathways in cells, which will create a basis for scientific community working in this area to develop novel molecules with better therapeutic efficacy. The bright future of exceptionally noncytotoxic derivatives of bisbenzimidazoles is also described as radiomodulators. Amifostine, an effective radioprotectant, has been approved by the FDA for limited clinical use. However, due to its adverse side effects, it is not routinely used clinically. Recently, CBLB502 and several analog of a peptide are under clinical trial and showed high success against radiotherapy in cancer. This article reviews the different types of radioprotective agents with emphasis on the strategies for the development of novel radioprotectors for drug development. In addition, direction for future strategies relevant to the development of radioprotectors is also addressed.

Novel regenerative peptide TP508 mitigates radiation-induced gastrointestinal damage by activating stem cells and preserving crypt integrity

In recent years, increasing threats of radiation exposure and nuclear disasters have become a significant concern for the United States and countries worldwide. Exposure to high doses of radiation triggers a number of potentially lethal effects. Among the most severe is the gastrointestinal (GI) toxicity syndrome caused by the destruction of the intestinal barrier, resulting in bacterial translocation, systemic bacteremia, sepsis, and death. The lack of effective radioprotective agents capable of mitigating radiation-induced damage has prompted a search for novel countermeasures that can mitigate the effects of radiation post exposure, accelerate tissue repair in radiation-exposed individuals, and prevent mortality. We report that a single injection of regenerative peptide TP508 (rusalatide acetate, Chrysalin) 24 h after lethal radiation exposure (9 Gy, LD100/15) appears to significantly increase survival and delay mortality by mitigating radiation-induced intestinal and colonic toxicity. TP508 treatment post exposure prevents the disintegration of GI crypts, stimulates the expression of adherens junction protein E-cadherin, activates crypt cell proliferation, and decreases apoptosis. TP508 post-exposure treatment also upregulates the expression of DCLK1 and LGR5 markers of stem cells that have been shown to be responsible for maintaining and regenerating intestinal crypts. Thus, TP508 appears to mitigate the effects of GI toxicity by activating radioresistant stem cells and increasing the stemness potential of crypts to maintain and restore intestinal integrity. These results suggest that TP508 may be an effective emergency nuclear countermeasure that could be delivered within 24 h post exposure to increase survival and delay mortality, giving victims time to reach clinical sites for advanced medical treatment.

Hemorrhage Exacerbates Radiation Effects on Survival, Leukocytopenia, Thrombopenia, Erythropenia, Bone Marrow Cell Depletion and Hematopoiesis, and Inflammation-Associated microRNAs Expression in Kidney

Exposure to high-dose radiation results in detrimental effects on survival. The effects of combined trauma, such as radiation in combination with hemorrhage, the typical injury of victims exposed to a radiation blast, on survival and hematopoietic effects have yet to be understood. The purpose of this study was to evaluate the effects of radiation injury (RI) combined with hemorrhage (i.e., combined injury, CI) on survival and hematopoietic effects, and to investigate whether hemorrhage (Hemo) enhanced RI-induced mortality and hematopoietic syndrome. Male CD2F1 mice (10 weeks old) were given one single exposure of γ- radiation (60Co) at various doses (0.6 Gy/min). Within 2 hr after RI, animals under anesthesia were bled 0% (Sham) or 20% (Hemo) of total blood volume via the submandibular vein. In these mice, Hemo reduced the LD50/30 for 30-day survival from 9.1 Gy (RI) to 8.75 Gy (CI) with a DMF of 1.046. RI resulted in leukocytopenia, thrombopenia, erythropenia, and bone marrow cell depletion, but decreased the caspase-3 activation response. RI increased IL-1β, IL-6, IL-17A, and TNF-α concentrations in serum, bone marrow, ileum, spleen, and kidney. Some of these adverse alterations were magnified by CI. Erythropoietin production was increased in kidney and blood more after CI than RI. Furthermore, CI altered the global miRNAs expression in kidney and the ingenuity pathway analysis showed that miRNAs viz., let-7e, miR-30e and miR-29b that were associated with hematopoiesis and inflammation. This study provides preliminary evidence that non-lethal Hemo exacerbates RI-induced mortality and cell losses associated with high-dose γ-radiation. We identified some of the initial changes occurring due to CI which may have facilitated in worsening the injury and hampering the recovery of animals ultimately resulting in higher mortality.

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.

Inhibition of heat shock protein 90 alleviates steatosis and macrophage activation in murine alcoholic liver injury

BACKGROUND & AIMS

Heat shock protein 90 (hsp90) is an emerging therapeutic target in chronic liver diseases. Hsp90 plays an important role in liver immune cell activation; however its role in alcoholic liver disease (ALD) remains elusive. Here we hypothesize that hsp90 is crucial in alcohol induced steatosis and pro-inflammatory cytokine production. To test this hypothesis, we employed a pharmacological inhibitor of hsp90, 17-DMAG (17-Dimethylamino-ethylamino-17-demethoxygeldanamycin) in an in vivo mouse model of acute and chronic alcoholic liver injury.

METHODS

C57BL/6 mice were given either a single dose of ethanol via oral gavage (acute) or chronically fed alcohol for 2 weeks followed by oral gavage (chronic-binge). 17-DMAG was administered during or at the end of feeding. Liver injury parameters, inflammatory cytokines and lipid metabolism genes were analysed.

RESULTS

Our results reveal increased expression of hsp90 in human and mouse alcoholic livers. In vivo inhibition of hsp90, using 17-DMAG, not only prevented but also alleviated alcoholic liver injury, determined by lower serum ALT, AST and reduced hepatic triglycerides. Mechanistic analysis showed that 17-DMAG decreased alcohol mediated oxidative stress, reduced serum endotoxin, decreased inflammatory cells, and diminished sensitization of liver macrophages to LPS, resulting in downregulation of CD14, NFκB inhibition, and decreased pro-inflammatory cytokine production. Hsp90 inhibition decreased fatty acid synthesis genes via reduced nuclear SREBP-1 and favoured fatty acid oxidation genes via PPARα.

CONCLUSIONS

Inhibition of hsp90 decreased alcohol induced steatosis and pro-inflammatory cytokines and inhibited alcoholic liver injury. Hsp90 is therefore relevant in human alcoholic cirrhosis and a promising therapeutic target in ALD.

Dissecting the molecular mechanism of ionizing radiation-induced tissue damage in the feather follicle

Ionizing radiation (IR) is a common therapeutic agent in cancer therapy. It damages normal tissue and causes side effects including dermatitis and mucositis. Here we use the feather follicle as a model to investigate the mechanism of IR-induced tissue damage, because any perturbation of feather growth will be clearly recorded in its regular yet complex morphology. We find that IR induces defects in feather formation in a dose-dependent manner. No abnormality was observed at 5 Gy. A transient, reversible perturbation of feather growth was induced at 10 Gy, leading to defects in the feather structure. This perturbation became irreversible at 20 Gy. Molecular and cellular analysis revealed P53 activation, DNA damage and repair, cell cycle arrest and apoptosis in the pathobiology. IR also induces patterning defects in feather formation, with disrupted branching morphogenesis. This perturbation is mediated by cytokine production and Stat1 activation, as manipulation of cytokine levels or ectopic Stat1 over-expression also led to irregular feather branching. Furthermore, AG-490, a chemical inhibitor of Stat1 signaling, can partially rescue IR-induced tissue damage. Our results suggest that the feather follicle could serve as a useful model to address the in vivo impact of the many mechanisms of IR-induced tissue damage.

Bone Marrow Mesenchymal Stem Cells Increase Survival after Ionizing Irradiation Combined with Wound Trauma: Characterization and Therapy

The aim of this study was to investigate whether treatment with mesenchymal stem cells (MSCs) could improve survival after radiation combined injury. Bone marrow MSCs (BMSCs) were isolated from femurs of B6D2F1/J female mice and were expanded and cultivated in hypoxic conditions (5% O₂, 10% CO₂, 85% N₂) over 30 days. BMSCs were transfused to mice 24 hr after combined injury due to ⁶⁰Co-γ-photon irradiation (9.25 and 9.75 Gy, 0.4 Gy/min, bilateral) followed by skin wounding (CI). Water consumption, body weight, wound healing, and survival tallies were monitored during observation period. Mice subjected to CI experienced a dramatic moribundity over a 30-day observation period. Thus, CI (9.25 Gy)-animal group was characterized by 40% mortality rate while CI (9.75 Gy)-animal group had 100% mortality rate. CI-induced sickness was accompanied by body weight loss, increased water intake, and delayed wound healing. At the 30th day post-injury, bone marrow cell depletion still remained in surviving CI mice. Treatment of CI (9.25 Gy)-animal group with BMSCs led to an increase in 30-day survival rate by 30%, attenuated body weight loss, accelerated wound healing rate, and ameliorated bone-marrow cell depletion. Our novel results are the first to suggest that BMSC therapy is efficacious to sustain animal survival after CI.