Sublethal Doses Of Irradiation Research Articles

Targeting NKG2D ligands in glioblastoma with a bispecific T-cell engager is augmented with conventional therapy and enhances oncolytic virotherapy of glioma stem-like cells

BackgroundGlioblastoma (GBM) almost invariably becomes resistant towards conventional treatment of radiotherapy and temozolomide (TMZ) chemotherapy, partly due to subpopulations of intrinsically resistant glioma stem-like cells (GSC). The oncolytic herpes simplex...

Is there Chornobyl nuclear accident signature in Scots pine radial growth and its climate sensitivity?

The extensive radioactive fallout resulting from the 1986 Chornobyl accident caused tree death near the nuclear power plant and perturbed trees communities throughout the whole Chornobyl exclusion zone. Thirty years into the post-accident period, the radiation continues to exert its fatal effects on the surviving trees. However, to what extent the continuous multi-decadal radiation exposure has affected the radial tree growth and its sensitivity to climate variation remains unascertained. In this comparative study, we measure the Scots pine radial growth and quantify its response to climate at two sites along the western track of the nuclear fallout that received significantly different doses of radiation in 1986. The common features of the two sites allow us to disentangle and intercompare the effects of sub-lethal and moderate radiation doses on the pine's growth and climatic sensitivity. We extend the response function analysis by making the first use of the Full-Duration at Half-Maximum FDHM method in dendrochronology and apply the double-moving window approach to detect the main patterns of the growth-to-climate relationships and their temporal evolution. The stand exposed to sub-lethal radiation shows a significant radial growth reduction in 1986 with a deflection period of one year. The stand exposed to moderate radiation, in contrast, demonstrates no significant decrease in growth either in 1986 or in the following years. Beyond the radiation effects, the moving response function and FDHM enabled us to detect several mutual patterns in the growth-to-climate relationships, which are seemingly unrelated to the nuclear accident. To advance our predictive understanding of the response of forest ecosystems to a massive radioactive contamination, future studies should include quantitative wood anatomy techniques.

UVA as environmental signal for alginate production in Pseudomonas aeruginosa: role of this polysaccharide in the protection of planktonic cells and biofilms against lethal UVA doses.

Pseudomonas aeruginosa is an extremely versatile microorganism that survives in a wide variety of niches. It is capable to respond rapidly to changes in the environment by producing secondary metabolites and virulence factors, including alginate. Alginate is an extracellular polysaccharide that protects the bacteria from antibiotics and oxidative agents, and enhances cell adhesion to solid surfaces in the process of biofilm formation. In the present study, we analyzed the role of alginate in the response of P. aeruginosa to lethal doses of ultraviolet-A (UVA) radiation, the major fraction of solar UV radiation reaching the Earth's surface. We also studied the role of alginate in the context of the adaptive responses generated when P. aeruginosa is exposed to sublethal doses of UVA radiation. The survival studies demonstrated that alginate has a key role in the resistance of P. aeruginosa to the oxidative stress generated by lethal UVA doses, both in planktonic cells and in static biofilms. In addition, the presence of alginate proved to be essential in the occurrence of adaptive responses such as induction of biofilm formation and cross-protection against hydrogen peroxide and sodium hypochlorite, both generated by exposure to low UVA doses. Finally, we demonstrated that the increase of biofilm formation is accompanied by an increase in alginate concentration in the biofilm matrix, possibly through the ppGpp-dependent induction of genes related to alginate regulation (algR and algU) and biosynthesis (algD operon). Given the importance of alginate in biofilm formation and its protective roles, better understanding of the mechanisms associated to its functions and synthesis is relevant, given the normal exposure of P. aeruginosa to UVA radiation and other types of oxidative stresses.

Mitigating effects of sublethal and lethal whole-body gamma irradiation in a mouse model with soluble melanin

The field of radiation countermeasures is growing, however, currently there are no effective and non-toxic compounds which could be administered orally to the individuals post exposure to high doses of ionising radiation. The pigment melanin is ubiquitous through all kingdoms of life and provides selective advantage under radiation stress through its role as a chemical and physical shield, and its capacity to respond and react to exposures. Soluble allomelanin was administered to mice following whole-body exposure to lethal or sublethal doses of gamma radiation to determine its capacity to mitigate the effects of acute radiation syndrome, and its utility as a radiation countermeasure. Allomelanin has shown a trend to improve survival post an 8 Gy sublethal radiation exposure when administered up to 48 h post-irradiation. Furthermore, it improved median and overall survival to a 10 Gy lethal radiation exposure, specifically when administered at 24 h post-irradiation. Histological analysis on the jejunum region of the small intestine of this treatment group indicated that alterations of the mucosal and submucosal architecture, and disruption of the lymphatic system associated with lethal radiation exposure were mitigated when allomelanin was administered at 24 h post-irradiation. Based on this work soluble allomelanin derived from a fungal source could serve as an easily sourced, cost-effective, and viable countermeasure to accidental radiation exposure and merits further investigation.

Amelioration of Radiation-Induced DNA Damage and Immunosuppression by Tanacetum parthenium leaf extract and synthetic parthenolide in Swiss Albino Mice

Radiotherapy potentially offers protection from recurrence of tumor that also causes normal tissue damage and creates major concern. Another important factor is long-term immune suppression in patients treated with radiotherapy. Therefore, crucial need for the survival of surrounding normal cells of tumor by radiation‑protecting agents is the prime focus of this study. Aqueous extract (AE) and ethanolic extract (EE), Tanacetum parthenium extracts100 mg/kg each and parthenolide (PAR) 4mg/kg body weight were orally administered prior to sub-lethal radiation dose exposure. Mice were used for the evaluation of radiation-mediated chromosomal aberrations in bone marrow cells and DNA break by comet assay in the blood lymphocytes of mice. The pro-inflammatory levels were determined by cytokine estimations namely interleukin‑2, interferongamma and tumor necrosis factor-alpha performed in the liver homogenate using ELISA kits. Thus the results demonstrated ameliorating, radio-mitigating and immune-stimulatory efficacy of AE, EE and PAR against radiation ‑induced DNA damage and immunosuppression by regulating cytokine.

The Effects of Ionising and Non-Ionising Electromagnetic Radiation on Extracellular Matrix Proteins.

Exposure to sub-lethal doses of ionising and non-ionising electromagnetic radiation can impact human health and well-being as a consequence of, for example, the side effects of radiotherapy (therapeutic X-ray exposure) and accelerated skin ageing (chronic exposure to ultraviolet radiation: UVR). Whilst attention has focused primarily on the interaction of electromagnetic radiation with cells and cellular components, radiation-induced damage to long-lived extracellular matrix (ECM) proteins has the potential to profoundly affect tissue structure, composition and function. This review focuses on the current understanding of the biological effects of ionising and non-ionising radiation on the ECM of breast stroma and skin dermis, respectively. Although there is some experimental evidence for radiation-induced damage to ECM proteins, compared with the well-characterised impact of radiation exposure on cell biology, the structural, functional, and ultimately clinical consequences of ECM irradiation remain poorly defined.

The use of gamma irradiation to stimulate bioactive compound synthesis in Inonotus obliquus submerged cultures

Abstract Inonotus obliquus is a parasite on the birch and other trees and is also a well-known medicinal mushroom. Its sterile conk is highly sought for its bioactive compounds such as phenols, polysaccharides, triterpenoids, and steroids. It was traditionally used to treat various gastrointestinal diseases, viral and parasitic infections, to counteract the progression of cancers, and to stimulate the immune system. We used acute gamma irradiation, followed by short-term submerged cultivation, as an oxidative stress inducer to enhance the synthesis of mycelial metabolites. The 300 Gy and 400 Gy doses showed the best results across the whole experimental design. Each assayed criterion had a different corresponding optimal stimulation dose. In one experiment, sublethal doses of irradiation triggered the dry weight of the cultured mycelium to increase by 19.764%. The free radical scavenging potential of the mycelium extracts increased by 79.83%. The total phenolic content of mycelium extracts and culture broth increased by 55.7% and 62.987%, respectively. The total flavonoid and sinapinic acid content of the broth increased by 934.678% and 590.395%, respectively. As such, gamma irradiation pre-treatment of the mycelial inoculum proved an interesting, economically and environmentally effective tool for stimulating secondary metabolite synthesis in submerged mycelium cultures.

Bone marrow transplantation without myeloablative conditioning in a mouse model for Diamond-Blackfan anemia corrects the disease phenotype

Diamond-Blackfan anemia (DBA) is a congenital erythroid hypoplasia caused by a functional haploinsufficiency of genes coding for ribosomal proteins. Among these genes, the ribosomal protein S19 (RPS19) gene is the most frequently mutated. Previously, a mouse model deficient in RPS19 was developed by our laboratory, which recapitulates the hematopoietic disease phenotype by manifesting pathologic features and clinical symptoms of DBA. Characterization of this model revealed that chronic RPS19 deficiency leads to exhaustion of hematopoietic stem cells and subsequent bone marrow (BM) failure. In this study, we evaluated a nonmyeloablative conditioning protocol for BM transplants in RPS19-deficient mice by transplanting wild-type BM cells to RPS19-deficient recipients given no conditioning or sublethal doses of irradiation before transplant. We describe full correction of the hematopoietic phenotype in mice given sublethal doses of irradiation, as well as in animals completely devoid of any preceding irradiation. In comparison, wild-type animals receiving the same preconditioning regimen and number of transplanted cells exhibited significantly lower engraftment levels. Thus, robust engraftment and repopulation of transplanted cells can be achieved in reduced-intensity conditioned RPS19-deficient recipients. As gene therapy studies with autologous gene-corrected hematopoietic stem cells are emerging, we propose the results described here can guide determination of the level of conditioning for such a protocol in RPS19-deficient DBA. On the basis of our findings, a relatively mild conditioning strategy would plausibly be sufficient to achieve sufficient levels of engraftment and clinical success.

RRx-001 Radioprotection: Enhancement of Survival and Hematopoietic Recovery in Gamma-Irradiated Mice.

The present studies evaluate the in vivo prophylactic radioprotective effects of 1-bromoacetyl-3, 3-dinitroazetidine (RRx-001), a phase III anticancer agent that inhibits c-myc and downregulates CD-47, after total body irradiation (TBI), in lethally and sublethally irradiated CD2F1 male mice. A single dose of RRx-001 was administered by intraperitoneal (IP) injection 24 h prior to a lethal or sublethal radiation dose. When irradiated with 9.35 Gy, the dose lethal to 70% of untreated mice at 30 days (LD70/30), only 33% of mice receiving RRx-001 (10 mg/kg) 24 h prior to total body irradiation (TBI) died by day 30, compared to 67% in vehicle-treated mice. The same pretreatment dose of RRx-001 resulted in a significant dose reduction factor of 1.07. In sublethally TBI mice, bone marrow cellularity was increased at day 14 in the RRx-001-treated mice compared to irradiated vehicle-treated animals. In addition, significantly higher numbers of lymphocytes, platelets, percent hematocrit and percent reticulocytes were observed on days 7 and/or 14 in RRx-001-treated mice. These experiments provide proof of principle that systemic administration of RRx-001 prior to TBI significantly improves overall survival and bone marrow regeneration.

Evaluation of Lipid Peroxidation under Immobilization Stress in Irradiated Animals in Experiment

BACKGROUND: For many years, the world community has been concerned with the problem of the consequences of radiation exposure on the human body. A wide range of possible variants of radiation effects on humans and biota determines the range of necessary pharmacological means of protecting the organism and populations. In the mechanisms of the formation of radioresistance, the leading role is assigned to the processes of lipid peroxidation (LPO) and the antioxidant (AO) system. The study of the effect of such factors as radiation and immobilization stress on the body separately and in combination is relevant since the modern conditions of human habitation are characterized by high urbanization, physical inactivity, and a complex radioecological situation in a number of regions. AIM: The aim of the study was to study the role of free radical oxidation in the tissues of the adrenal glands and immunocompetent organs and cells under the combined effect of a sublethal dose of gamma radiation and immobilization stress in the experiment. MATERIALS AND METHODS: The work was carried out on 40 male Wistar rats: I-control; II-subjected to immobilization stress after 1 h; III-exposed to gamma irradiation; and IV-tested combined effects (immobilization stress and gamma radiation). Before the exposure, there was topometric-dosimetric preparation of the experimental animals. To this end, the object was placed on an isocentric therapeutic desk of Terasix X-ray simulator (Czech Republic), which is similar to the therapeutic desk of the γ-irradiator by its construction and parameters. RESULTS: The results obtained make it possible to assess the role of free radical oxidation under the combined action of ionizing radiation at a sublethal dose and immobilization stress in the experiment. The combined effect was accompanied by the accumulation of diene conjugates and malondialdehyde products in homogenates and the development of double oxidative stress in the test objects. The dominant role of ionizing radiation was revealed under the combined effects of immobilization stress and radiation factor. CONCLUSIONS: In animals of the 4th group, the state of oxidative-metabolic processes was characterized by overproduction of LPO products and subsequently by depression of AO defense. The urgency of continuing research on the combined effects of radiation and stress factors on public health and taking measures to eliminate negative effects on the population seems to be undoubted.

Melatonin-Caffeine Combination Modulates Gamma Radiation-induced Sperm Malformations in C57BL/6 Male Mice at Sublethal Dose of Gamma Radiation.

Aims:The aim of this study was to assess the protective effect of the melatonin–caffeine combination against γ radiation-induced alterations in the morphological characteristics of sperms.Settings and Design:C57BL/6 male mice (n = 30) were randomly divided into five groups: control, radiation (2 Gy), melatonin (100 mg/kg body wt.) + radiation (2 Gy), caffeine (30 mg/kg body wt.) + radiation (2 Gy), melatonin–caffeine (100–30 mg/kg body wt.) + radiation (2 Gy).Materials and Methods:All the mice were sacrificed 24 h postirradiation, and cauda epididymis was collected. In this study, sperm concentration along with any abnormality in their morphology (amorphous heads, pinheads, hookless, coiled tails, midpiece defect, and tail-less) was observed in the control and treatment group of animals.Results:Radiation exposure (2 Gy) considerably decreases the sperm count when compared with the control group. However, pretreatment with melatonin and melatonin–caffeine combination before gamma irradiation increased the sperm count (P < 0.05), but with caffeine alone could not produce a significant difference. The higher rate of abnormal sperms was observed in the γ-irradiated mice when compared with the control group (P < 0.05). Besides, the numbers of sperm that are hookless and coiled tails were significantly increased after irradiation. Melatonin significantly reduced the number of sperm with amorphous heads and coiled tails. Melatonin–caffeine combination further reduced sperm malformations when compared with the melatonin + 2 Gy radiation and caffeine + 2 Gy radiation group.Conclusions:This study suggests that caffeine exerts a protective effect when given in combination with melatonin against gamma irradiation in sperms of C57BL/6 mice and could be a potent combination for the development of radioprotector.

Small subset of Wnt-activated cells is an initiator of regrowth in colorectal cancer organoids after irradiation.

Most colorectal cancers (CRCs) are differentiated adenocarcinomas, which maintain expression of both stemness and differentiation markers. This observation suggests that CRC cells could retain a regeneration system of normal cells upon injury. However, the role of stemness in cancer cell regeneration after irradiation is poorly understood. Here, we examined the effect of radiation on growth, stemness, and differentiation in organoids derived from differentiated adenocarcinomas. Following a sublethal dose of irradiation, proliferation and stemness markers, including Wnt target genes, were drastically reduced, but differentiation markers remained. After a static growth phase after high dose of radiation, regrowth foci appeared; these consisted of highly proliferating cells that expressed stem cell markers. Radiosensitivity and the ability to form foci differed among the cancer tissue‐originated spheroid (CTOS) lines examined and showed good correlation with in vivo radiation sensitivity. Pre‐treating organoids with histone deacetylase inhibitors increased radiation sensitivity; this increase was accompanied by the suppression of Wnt signal‐related gene expression. Accordingly, Wnt inhibitors increased organoid radiosensitivity. These results suggested that only a small subset of, but not all, cancer cells with high Wnt activity at the time of irradiation could give rise to foci formation. In conclusion, we established a radiation sensitivity assay using CRC organoids that could provide a novel platform for evaluating the effects of radiosensitizers on differentiated adenocarcinomas in CRC.

Serum Circulating MicroRNAs as Functional Biodosimeters in Patients Undergoing Total Body Irradiation

In a radiation exposure event, life-threatening doses of ionizing radiation may be delivered in a total-body irradiation (TBI) pattern. To triage victims and implement countermeasures, we need clinically feasible biodosimeters. Previously, we used mouse and non-human primate models to show that serum microRNAs may predict the biological impact of lethal and sublethal radiation doses. We hypothesized that these results can be replicated in humans subjected to TBI. We obtained sera from 25 patients who underwent allogeneic stem-cell transplantation conditioned with TBI (2 Gy/fx, total 12 Gy) in two radiation oncology centers. The sera were collected at the following timepoints: no irradiation, low dose (2 or 4 Gy; n = 25) and high dose (12 Gy, n = 9). We profiled microRNA expression in these samples using next-generation sequencing (miRNA-seq). Additionally, we isolated exosomes from paired serum samples of 6 patients at 0 Gy and 12 Gy and performed miRNA-seq on their contents. After quality control (filtering out samples with <350 miRNAs with non-zero expression), we deemed 68 of 71 samples suitable for downstream analysis. Differential expression results were largely consistent with previous non-human studies, with miR-150-5p significantly downregulated and miR-375 together with miR-200 and miR-30 families upregulated following exposure. Serum microRNA signatures showed near-perfect separation of irradiated and non-irradiated samples in the low dose setting (in cross-validation AUC 0.87, 95% confidence interval 0.76-0.98). Model built using 9 high dose vs 22 non-irradiated samples yielded in cross-validation AUC 0.86 (95% confidence interval 0.68-1.0). Paired analyses in low- and high dose settings allowed us to identify several microRNAs, including miR-150-5p, whose expression decreased in a linear manner with respect to radiation dose, identifying them as potential biodosimeters. Additionally, many of the differentially expressed miRNAs have been previously shown to directly target candidate biodosimeter proteins such as ATM (miR-181 family) or TP53 (miR-150-5p, miR-375, miR-30 families). MicroRNAs identified as differentially expressed in exosomes were largely consistent in terms of change with that observed in serum samples, however, due to low power, only miR-130a-3p was significantly up- and miR-193a-5p significantly downregulated (FDR<0.05). We confirm that serum microRNAs reflect radiation dose exposure of humans undergoing TBI and thus may be used as functional biodosimeters for precise identification of people exposed to clinically significant amounts of radiation. These findings have important implications in emergency medicine and in radiation oncology.

Asparagus racemosus Root Extract and Isoprinosine Exhibits Radio-mitigating Activity against Ionizing Radiation-induced Detrimental Effects in Swiss Albino Mice

Objectives: To evaluate the radio – mitigating property of Asparagus racemosus root ethanolic extract and Isoprinosine against ionizing radiationinduced harmful effects in Swiss albino mice. Methods: The experimental animals were exposed to sublethal dose (6 Gy) of whole-body electron beam radiation and administered orally with Asparagus racemosus root ethanolic extract (ARE – 200mg/kg bd. wt) and Isoprinosine (IPR – 400 mg/ kg bd. wt) for 15 consecutive days. After the experimental period, the animals were sacrificed. Blood and liver tissue were collected. Blood sample was used for assessment of hematological parameters, serum was used for biochemical analysis (lipid peroxidation, total antioxidant capacity) and the level of pro-inflammatory cytokines was determined in the liver homogenate. Results: The radiation control group showed a statistically significant reduction in the hematological parameters. IPR post-treatment group showed a substantial increase in the percentage of lymphocytes and monocytes. ARE and IPR post-treatment caused a statistically significant improvement in platelet count. Irradiation of mice resulted in a significant elevation in lipid peroxidation. Post-treatment of mice with ARE and IPR caused significant depletion in lipid peroxidation. The serum total antioxidant capacity (TAC) in the irradiated group decreased significantly. Administration of ARE to the animals after irradiation caused a significant elevation in TAC level. IPR post-treatment did not show any substantial change in the reduced level of TAC. The cytokines level in the liver homogenate of irradiated mice showed that Interleukin -2 (IL-2), Tumor Necrosis Factor alpha (TNF-α) and Interferon gamma (IFN-γ) significantly increased after radiation exposure. Administration of ARE and IPR after irradiation significantly reduced the levels of IL-2 and TNF-α in the posttreatment groups. An elevated level of IFN-γ was reduced considerably in the IPR post-treatment animals. Conclusion: Asparagus racemosus root ethanolic extract and Isoprinosine exhibit radio-mitigating effects against electron beam radiation - induced detrimental effects. This occurs through several mechanisms, such as free radical scavenging, anti-inflammation, facilitation of repair activity, regeneration of hematopoietic cells and affecting to molecular levels. Key words: Asparagus racemosus, Isoprinosine, Radio-mitigation, Ionizing radiation.

20. MELANOMA CELL INTRINSIC GABAA RECEPTOR ENHANCEMENT POTENTIATES RADIATION AND IMMUNE CHECKPOINT INHIBITOR RESPONSE BY PROMOTING DIRECT AND T CELL-MEDIATED ANTI-TUMOR ACTIVITY

Most metastatic melanoma patients exhibit poor and variable response to radiotherapy and targeted therapies, including immune checkpoint inhibitors. There is a need for therapeutics that can potentiate existing treatments to positively impact clinical outcomes of metastatic melanoma patients. We reanalyzed melanoma TCGA transcriptomes and identified, as linked to previously defined molecular subgroups, enhanced expression of genes coding for subunits of the Type A GABA receptor (GABAAR), a chloride ion channel and major inhibitory neurotransmitter receptor. Using whole-cell patch clamp electrophysiology, we find that melanoma cells possess GABAARs that control membrane permeability to anions. Select benzodiazepines, by enhancing GABAAR mediated anion transport, depolarize melanoma cell mitochondrial membrane potential and impair cell viability in vitro. Using a syngeneic melanoma mouse model, we find that a benzodiazepine promotes reduction in tumor volume when administered alone and potentiated radiation or immune checkpoint inhibitor α-PD-L1. When a benzodiazepine is combined with concurrent α-PD-L1 and a sub-lethal radiation dose, there is near complete loss of tumor, beyond what is observed for benzodiazepine with radiation or α-PD-L1. Mechanistically, benzodiazepine with radiation or α-PD-L1 results in ipsilateral and an abscopal tumor volume reduction commensurate with enhanced infiltration into the tumor milieu of polyfunctional CD8 T-cells. There is also an increased expression of genes with roles in the cytokine-cytokine receptor and p53 signaling pathways. This study provides evidence for melanoma cell GABAARs as a therapeutic vulnerability with benzodiazepines promoting both direct and immune-mediated anti-tumor activity.

Single-Dose Administration of Recombinant Human Thrombopoietin Mitigates Total Body Irradiation-Induced Hematopoietic System Injury in Mice and Nonhuman Primates

Recombinant human thrombopoietin (rhTPO) has been evaluated as a therapeutic intervention for radiation-induced myelosuppression. However, the immunogenicity induced by a repeated-dosing strategy raises concerns about the therapeutic use of rhTPO. In this study, single-dose administration of rhTPO was evaluated for efficacy in the hematopoietic response and survival effect on mice and nonhuman primates exposed to total body irradiation (TBI). Survival of lethally (9.0 Gy) irradiated C57BL/6J male mice was observed for 30 days after irradiation. Hematologic evaluations were performed on C57BL/6J male mice given a sublethal dose of radiation (6.5 Gy). Furthermore, in sublethally irradiated mice, we performed bone marrow (BM) histologic evaluation and evaluated BM-derived clonogenic activity. Next, the proportion and number of hematopoietic stem cells (HSCs) were analyzed. Competitive repopulation experiments were conducted to assess the multilineage engraftment of irradiated HSCs after BM transplantation. Flow cytometry was used to evaluate DNA damage, cell apoptosis, and cell cycle stage in HSCs after irradiation. Finally, we evaluated the efficacy of a single dose of rhTPO administered after 7 Gy TBI in male and female rhesus monkeys. A single administration of rhTPO 2 hours after irradiation significantly mitigated TBI-induced death in mice. rhTPO promoted multilineage hematopoietic recovery, increasing peripheral blood cell counts, BM cellularity, and BM colony-forming ability. rhTPO administration led to an accelerated recovery of BM HSC frequency and multilineage engraftment after transplantation. rhTPO treatment reduced radiation-induced DNA damage and apoptosis and promoted HSC proliferation after TBI. Notably, a single administration of rhTPO significantly promoted multilineage hematopoietic recovery and improved survival in nonhuman primates after TBI. These findings indicate that early intervention with a single administration of rhTPO may represent a promising and effective radiomitigative strategy for victims of radiation disasters.

Interleukin-33 regulates hematopoietic stem cell regeneration after radiation injury

BackgroundIL-33 is a pleiotropic cytokine of the IL-1 family, which has been reported to implicate in both innate and adaptive immune responses. Recent studies suggest IL-33 is crucial for regulation of myelopoiesis and myeloid cell activity. Here, we explore the potential effect of IL-33 against hematopoietic injury after total body irradiation (TBI).MethodsC57BL/6 mice were irradiated with a sublethal dose of radiation (600 cGy) and treated with IL-33 at a dose of 3 μg/dose i.p. once a day for seven consecutive days. H&E staining was used to determine the bone marrow cellularity. A flow cytometer was used to quantify the hematopoietic stem cell (HSC) population, cell proliferation, and apoptosis. The colony-forming assay was used to evaluate the clonogenic function of HSCs. RT-qPCR was used to determine the expression of apoptosis-associated genes.ResultsBone marrow HSCs from wild-type mice expressed functional IL-33 receptor (ST2), and treatment with IL-33 promoted the recovery of the HSC pool in vivo and improved the survival of mice after TBI. Conversely, mice with ST2 deficiency showed decreased HSC regeneration and mouse survival after TBI. Of note, IL-33 reduced radiation-induced apoptosis of HSCs and mediated this effect through repression of the p53-PUMA pathway.ConclusionsIL-33 regulates HSC regeneration after myelosuppressive injury through protecting HSCs from apoptosis and enhancing proliferation of the surviving HSCs.

Icariin protects against radiation-induced mortality and damage in vitro and in vivo

Purpose: The present study aimed to investigate the potential protective effects of icariin both in vivo and in vitro, an active flavonoid glucoside derived from medicinal herb Epimedium, and its possible mechanisms against radiation-induced injury.Methods: Male C57BL/6 mice were exposed to lethal dose (7 Gy) or sub-lethal dose (4 Gy) of whole body radiation by X-ray at a dose rate of ∼0.55 Gy/min, and icariin was given three times at 24 h and 30 min before and 24 h after the irradiation. After irradiation, hematological, biochemical, and histological evaluations were performed. We further determined the effect of icariin on radiation-induced cytotoxicity and changes in apoptosis-related protein expression.Results: Icariin enhanced the 30-day survival rates (20 and 40 mg/kg) in a dose-dependent manner, and protected the radiosensitive organs such as intestine and testis from the radiation damages. Moreover, hematopoietic damage by radiation was significantly decreased in icariin-treated mice as demonstrated by the increases in number of peripheral blood cells, bone marrow cells (1.7-fold), and spleen colony forming units (1.7-fold). In addition, icariin decreased the radiation-induced oxidative stress by modulating endogenous antioxidant levels. Subsequent in vitro studies showed that icariin effectively increased cell viability (1.4-fold) and suppressed the expression of apoptosis-related proteins after irradiation.Conclusion: These results suggest that icariin has significant protective effects against radiation-induced damages partly through its anti-oxidative and anti-apoptotic properties.

Regulation of five-antibiotic mixture on Microcystis aeruginosa exposed to sublethal doses of ultraviolet radiation

Previous reports suggested that coexisting antibiotics could enhance cyanobacterial growth and cyanotoxin production, but the influence of antibiotics on cyanobacterial removal has not been reported. This study investigated regulation effects and mechanisms of mixed antibiotics (ciprofloxacin, amoxicillin, sulfamethoxazole, tetracycline and spiramycin) in Microcystis aeruginosa exposed to UV-B and UV-C radiation at their current contamination level of 200 ng L−1. Mixed antibiotics alleviated growth inhibition effects of 240–480 mJ cm−2 of UV-B and 48–144 mJ cm−2 of UV-C, while enhanced the growth inhibition effects of 240 mJ cm−2 of UV-C. Responses of chlorophyll-a suggested that mixed antibiotics may regulate the toxicity of UV radiation via photosynthesis. Mixed antibiotics increased the production of microcystins in UV-treated M. aeruginosa, which may cause further hazard to the aquatic environment. Superoxide dismutase activity, growth rate and cell density varied in a similar pattern under exposure to UV radiation and mixed antibiotics, suggesting the correlation between cyanobacterial growth and reactive oxygen species during the UV treatment regulated by antibiotics. Responses of malondialdehyde suggested a higher toxicity of UV-C than UV-B to M. aeruginosa under the regulation of mixed antibiotics. With the coexistence of antibiotic contaminants, the radiation dose should be increased during the removal of M. aeruginosa by UV treatment.

Endothelial Cell-Derived Extracellular Vesicles Mitigate Radiation-Induced Hematopoietic Injury

Hematopoietic stem cells (HSCs) reside in specialized microenvironments and adjacent to endothelial cells (ECs), from which they receive regulatory cues. Following injury from radiation or chemotherapy, transplanted ECs can facilitate hematopoietic regeneration. Since these ECs do not engraft in the marrow, we hypothesize that ECs facilitate hematopoietic regeneration through secretion of extracellular vesicles (EVs). EVs are becoming recognized as a mode of cell-to-cell communication through transfer of their cargo of nucleic acids and proteins. Using ultracentrifugation, we visualized these EVs by transmission electron microscopy and measured their size to be a mean size of 160 nm (range 121-217 nm, n=18). Using flow cytometric analysis with Syto13, we demonstrate that these EVs contain nucleic acids in 30% of the particles. Quantitative real-time PCR show that these EVs express CD31 and VECadherin, and not Fibroblast Specific Marker 1 (FSP1), indicating EVs bear EC markers. At day 7 following 300 cGy, C57BL/6 cKit+Sca-1+Lineage- (KSL) cells cultured with EVs demonstrated total cell expansion and colony-forming unit cells (CFCs) compared to cultures with cytokines alone (*p< 0.0001 and 0.01, respectively, n= 3-6/group). Following myelosuppressive, sub-lethal radiation dose of 500 cGy, C57BL/6 mice treated with EVs on days 1-4 display increased marrow cellularity (*p= 0.003, n= 2-3/group), preserved vascular endothelial cells by mouse endothelial cell antigen immunohistochemistry (*p=0.03, n=2-4/group), CD150+CD48-KSL cells (*p= 0.03, n= 5/group), and increased CFCs (*p= 0.03, n= 6/group) compared to saline-treated mice. No differences were detected in these parameters when EV-treated mice were compared to mice treated with primary, cultured C57BL/6 marrow ECs. Following lethal-dose irradiation of 800 cGy, mice that received EVs on day 1-4 display prolonged survival compared to saline-treated mice (*p= 0.008 by Log-rank Analysis, n= 10/group). At day 30 following irradiation, 5 of 10 mice were alive in the EV-treated group compared to 0 of 10 in the saline-treated group. No differences in survival were observed between EV-treated and EC-treated mice (p= 0.4). Treatment of irradiated C57BL/6 hematopoietic stem/progenitor cells (HSPCs) with EVs generated from a genetically distinct strain (BALB/c mice) showed similar levels of cell expansion and CFCs compared to treatment of HSPCs from syngeneic EVs. Our findings show that syngeneic or allogenic EVs could be cell-derived therapy to deliver physiologic doses of nucleic acids and growth factors to hematopoietic cells to accelerate hematopoietic regeneration. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.