Protective effect of total flavonoids of Engelhardia roxburghiana Wall. leaves against radiation-induced intestinal injury in mice and its mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Irradiation-induced intestinal injury (RIII) often occurs during radiotherapy in patients, which would result in abdominal pain, diarrhea, nausea, vomiting, and even death. Engelhardia roxburghiana Wall. leaves, a traditional Chinese herb, has unique anti-inflammatory, anti-tumor, antioxidant, and analgesic effects, is used to treat damp-heat diarrhea, hernia, and abdominal pain, and has the potential to protect against RIII.

AIM OF THE STUDY

To explore the protective effects of the total flavonoids of Engelhardia roxburghiana Wall. leaves (TFERL) on RIII and provide some reference for the application of Engelhardia roxburghiana Wall. leaves in the field of radiation protection.

MATERIALS AND METHODS

The effect of TFERL on the survival rate of mice was observed after a lethal radiation dose (7.2 Gy) by ionizing radiation (IR). To better observe the protective effects of the TFERL on RIII, a mice model of RIII induced by IR (13 Gy) was established. Small intestinal crypts, villi, intestinal stem cells (ISC) and the proliferation of ISC were observed by haematoxylin and eosin (H&E) and immunohistochemistry (IHC). Quantitative real-time PCR (qRT-PCR) was used to detect the expression of genes related to intestinal integrity. Superoxide dismutase (SOD), reduced glutathione (GSH), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in the serum of mice were assessed. In vitro, cell models of RIII induced by IR (2, 4, 6, 8 Gy) were established. Normal human intestinal epithelial cells HIEC-6 cells were treated with TFERL/Vehicle, and the radiation protective effect of TFERL on HIEC-6 cells was detected by clone formation assay. DNA damage was detected by comet assay and immunofluorescence assay. Reactive oxygen species (ROS), cell cycle and apoptosis rate were detected by flow cytometry. Oxidative stress, apoptosis and ferroptosis-related proteins were detected by western blot. Finally, the colony formation assay was used to detect the effect of TFERL on the radiosensitivity of colorectal cancer cells.

RESULTS

TFERL treatment can increase the survival rate and time of the mice after a lethal radiation dose. In the mice model of RIII induced by IR, TFERL alleviated RIII by reducing intestinal crypt/villi structural damage, increasing the number and proliferation of ISC, and maintaining the integrity of the intestinal epithelium after total abdominal irradiation. Moreover, TFERL promoted the proliferation of irradiated HIEC-6 cells, and reduced radiation-induced apoptosis and DNA damage. Mechanism studies have found that TFERL promotes the expression of NRF2 and its downstream antioxidant proteins, and silencing NRF2 resulted in the loss of radioprotection by TFERL, suggesting that TFERL exerts radiation protection by activating the NRF2 pathway. Surprisingly, TFERL reduced the number of clones of colon cancer cells after irradiation, suggesting that TFERL can increase the radiosensitivity of colon cancer cells.

CONCLUSION

Our data showed that TFERL inhibited oxidative stress, reduced DNA damage, reduced apoptosis and ferroptosis, and improved IR-induced RIII. This study may offer a fresh approach to using Chinese herbs for radioprotection.

IPW-5371 mitigates the delayed effects of acute radiation exposure in WAG/RijCmcr rats when started 15 days after PBI with bone marrow sparing

PURPOSE

To test IPW-5371 for the mitigation of the delayed effects of acute radiation exposure (DEARE). Survivors of acute radiation exposure are at risk for developing delayed multi-organ toxicities; however, there are no FDA-approved medical countermeasures (MCM) to mitigate DEARE.

METHODS

WAG/RijCmcr female rat model of partial-body irradiation (PBI), by shielding part of one hind leg, was used to test IPW-5371 (7 and 20 mg kg-1 d-1) for mitigation of lung and kidney DEARE when started 15 d after PBI. Rats were fed known amounts of IPW-5371 using a syringe, instead of delivery by daily oral gavage, sparing exacerbation of esophageal injury by radiation. The primary endpoint, all-cause morbidity was assessed over 215 d. Secondary endpoints: body weight, breathing rate and blood urea nitrogen were also assessed.

RESULTS

IPW-5371 enhanced survival (primary endpoint) as well as attenuated secondary endpoints of lung and kidney injuries by radiation.

CONCLUSION

To provide a window for dosimetry and triage, as well as avoid oral delivery during the acute radiation syndrome (ARS), the drug regimen was started at 15 d after 13.5 Gy PBI. The experimental design to test mitigation of DEARE was customized for translation in humans, using an animal model of radiation that was designed to simulate a radiologic attack or accident. The results support advanced development of IPW-5371 to mitigate lethal lung and kidney injuries after irradiation of multiple organs.

CRX-527 induced differentiation of HSCs protecting the intestinal epithelium from radiation damage

Recently, Toll-like receptors (TLRs) have been extensively studied in radiation damage, but the inherent defects of high toxicity and low efficacy of most TLR ligands limit their further clinical transformation. CRX-527, as a TLR4 ligand, has rarely been reported to protect against radiation. We demonstrated that CRX-527 was safer than LPS at the same dose in vivo and had almost no toxic effect in vitro. Administration of CRX-527 improved the survival rate of total body irradiation (TBI) to 100% in wild-type mice but not in TLR4-/- mice. After TBI, hematopoietic system damage was significantly alleviated, and the recovery period was accelerated in CRX-527-treated mice. Moreover, CRX-527 induced differentiation of HSCs and the stimulation of CRX-527 significantly increased the proportion and number of LSK cells and promoted their differentiation into macrophages, activating immune defense. Furthermore, we proposed an immune defense role for hematopoietic differentiation in the protection against intestinal radiation damage, and confirmed that macrophages invaded the intestines through peripheral blood to protect them from radiation damage. Meanwhile, CRX-527 maintained intestinal function and homeostasis, promoted the regeneration of intestinal stem cells, and protected intestinal injury from lethal dose irradiation. Furthermore, After the use of mice, we found that CRX-527 had no significant protective effect on the hematopoietic and intestinal systems of irradiated TLR4-/- mice. in conclusion, CRX-527 induced differentiation of HSCs protecting the intestinal epithelium from radiation damage.

Ferroptosis plays an important role in promoting ionizing radiation-induced intestinal injuries

The intestinal tract is an essential component of the body's immune system, and is extremely sensitive to exposure of ionizing radiation. While ionizing radiation can effectively induce multiple forms of cell death, whether it can also promote ferroptosis in intestinal cells and the possible interrelationship between ferroptosis and intestinal immune function has not been reported so far. Here, we found that radiation-induced major ultrastructural changes in mitochondria of small intestinal epithelial cells and the changes induced in iron content and MDA levels in the small intestine were consistent with that observed during cellular ferroptosis, thus suggesting occurrence of ferroptosis in radiation-induced intestinal damage. Moreover, radiation caused a substantial increase in the expression of ferroptosis-related factors such as LPCAT3 and ALOX15 mRNA, augmented the levels of immune-related factors INF-γ and TGF-β mRNA, and decreased the levels of IL-17 mRNA thereby indicating that ionizing radiation induced ferroptosis and impairment of intestinal immune function. Liproxstatin-1 is a ferroptosis inhibitor that was found to ameliorate radiation-induced ferroptosis and promote the recovery from immune imbalances. These findings supported the role of ferroptosis in radiation-induced intestinal immune injury and provide novel strategies for protection against radiation injury through regulation of the ferroptosis pathway.

Quercetin Prevents Radiation-Induced Oral Mucositis by Upregulating BMI-1

Radiation-induced oral mucositis is a major adverse event of radiotherapy. Severe oral mucositis may cause unwanted interruption in radiotherapy and reduce long-term survival in cancer patients receiving radiotherapy, but until now, there have been no effective options for preventing radiation-induced oral mucositis. Quercetin is a flavonoid that is widely found in food species and has anti-inflammatory, antioxidant, and anticancer activities. In this study, we investigated a new role of quercetin in preventing radiation-induced oral mucositis. Quercetin exerted preventive effects against radiation-induced oral mucositis induced by single-dose (25 Gy) ionizing radiation or fractionated ionizing radiation (8 Gy × 3) in C57BL/6 mice and maintained the proliferation ability of basal epithelial cells. Quercetin pretreatment alleviated reactive oxygen species generation, NF-κB pathway activation, and downstream proinflammatory cytokine production and reduced DNA double-strand breaks and cellular senescence induced by ionizing radiation. Quercetin also upregulated BMI-1 expression in oral epithelial cells and promoted ulcer repair. In addition, quercetin exerted similar radioprotective effects in irradiated primary cultured normal human keratinocytes, reduced reactive oxygen species generation and proinflammatory cytokine release, and promoted DNA double-strand break repair and wound healing by upregulating the expression of BMI-1, which is a polycomb group protein. Thus, quercetin can block multiple pathological processes of radiation-induced oral mucositis by targeting BMI-1 and may be a potential treatment option for preventing radiation-induced oral mucositis.

Rat Models of Partial-body Irradiation with Bone Marrow-sparing (Leg-out PBI) Designed for FDA Approval of Countermeasures for Mitigation of Acute and Delayed Injuries by Radiation

ABSTRACT

The goal of this study was to develop rat models of partial body irradiation with bone-marrow sparing (leg-out PBI) to test medical countermeasures (MCM) of both acute radiation syndrome (ARS) and delayed effects of acute radiation exposure (DEARE) under the FDA animal rule. The leg-out PBI models were developed in female and male WAG/RijCmcr rats at doses of 12.5-14.5 Gy. Rats received supportive care consisting of fluids and antibiotics. Gastrointestinal ARS (GI-ARS) was assessed by lethality to d 7 and diarrhea scoring to d 10. Differential blood counts were analyzed between d 1-42 for the natural history of hematopoietic ARS (H-ARS). Lethality and breathing intervals (BI) were measured between d 28-110 to assess delayed injury to the lung (L-DEARE). Kidney injury (K-DEARE) was evaluated by measuring elevation of blood urea nitrogen (BUN) between d 90-180. The LD50/30, including both lethality from GI-ARS and H-ARS, for female and male rats are 14.0 Gy and 13.5 Gy, respectively, while the LD50/7 for only GI-ARS are 14.3 Gy and 13.6 Gy, respectively. The all-cause mortalities, including ARS and L-DEARE, through 120 d (LD50/120) are 13.5 Gy and 12.9 Gy, respectively. Secondary end points confirmed occurrence of four distinct sequelae representing GI, hematopoietic, lung, and kidney toxicities after leg-out PBI. Adult rat models of leg-out PBI showed the acute and long-term sequelae of radiation damage that has been reported in human radiation exposure case studies. Sex-specific differences were observed in the DRR between females and males. These rat models are among the most useful for the development and approval of countermeasures for mitigation of radiation injuries under the FDA animal rule.

Assessment of cellular and molecular changes in the rat brain after gamma radiation and radioprotection by anisomycin

The objective of the study was to describe cellular and molecular markers of radioprotection by anisomycin, focusing on the changes in rat brain tissue. Two-month-old Wistar rats were exposed to a 60Co radiation source at a dose of 6 Gy, with or without radioprotection with anisomycin (150 mg/kg) administered subcutaneously 30 min before or 3 or 6 h after irradiation. Survivors were analyzed 30 days after treatment. Astroglial and microglial responses were investigated based on the expression of glial markers assessed with immunohistochemistry, and quantitative changes in brain biomolecules were investigated by Raman microspectroscopy. In addition, blood plasma levels of pro-inflammatory (interleukin 6 and tumor necrosis factor α) and anti-inflammatory (interleukin 10) cytokines were assessed. We found that application of anisomycin either before or after irradiation significantly decreased the expression of the microglial marker Iba-1. We also found an increased intensity of Raman spectral bands related to nucleic acids, as well as an increased level of cytokines when anisomycin was applied after irradiation. This suggests that the radioprotective effects of anisomycin are by decreasing Iba-1 expression and stabilizing genetic material by increasing the level of nucleic acids.

Metformin Protects against Radiation-Induced Acute Effects by Limiting Senescence of Bronchial-Epithelial Cells

Radiation-induced damage to normal lung parenchyma remains a dose-limiting factor in thorax-associated radiotherapy (RT). Severe early and late complications with lungs can increase the risk of morbidity in cancer patients after RT. Herein, senescence of lung epithelial cells following RT-induced cellular stress, or more precisely the respective altered secretory profile, the senescence-associated secretory phenotype (SASP), was suggested as a central process for the initiation and progression of pneumonitis and pulmonary fibrosis. We previously reported that abrogation of certain aspects of the secretome of senescent lung cells, in particular, signaling inhibition of the SASP-factor Ccl2/Mcp1 mediated radioprotection especially by limiting endothelial dysfunction. Here, we investigated the therapeutic potential of a combined metformin treatment to protect normal lung tissue from RT-induced senescence and associated lung injury using a preclinical mouse model of radiation-induced pneumopathy. Metformin treatment efficiently limited RT-induced senescence and SASP expression levels, thereby limiting vascular dysfunctions, namely increased vascular permeability associated with increased extravasation of circulating immune and tumor cells early after irradiation (acute effects). Complementary in vitro studies using normal lung epithelial cell lines confirmed the senescence-limiting effect of metformin following RT finally resulting in radioprotection, while fostering RT-induced cellular stress of cultured malignant epithelial cells accounting for radiosensitization. The radioprotective action of metformin for normal lung tissue without simultaneous protection or preferable radiosensitization of tumor tissue might increase tumor control probabilities and survival because higher radiation doses could be used.

Protective effects of Saraca indica L. leaves extract (family Fabaceae) against gamma irradiation induced injury in the kidney of female albino rats

This work was designed to estimate the protective effect of Saraca indica L. leaves ethanolic exract against γ-irradiation induced renal damage in rats. Phytochemical examinations of S. indica L. leaves extract resulted in the separation of three flavanone glycosides: Astilibin (1), Neoastilbin (2), and Eriodictyol-7-O-α-l-rhamnopyranoside (3); two flavonols: Quercetin (4) and Quercetin-3-O-α-l-arabinopyranosyl-(1'''-6'')-O-β-D-galactopyranoside (5) in addition of Gallic acid (6) and methyl gallate (7). Their structures elucidated by chemical evidences and spectroscopic analysis (1 and 2D-NMR, -ESI-MS, UV). Female rats were used and classified into: control, Ext (200 mg/kg body wt/day orally for 7 days), IRR (8Gy), Ext + IRR, and Sily+IRR groups (received silymarin 50 mg/kg b.wt orally as reference drug). Results showed that S. indica L. leaves extract ameliorated the kidney function tests, hs-CRP, IL-1β, ACE, TNF-α, GSH, and MDA as well as, decreased the histopathological changes of kidney. In conclusion, S. indica L. leaves extract had a renoprotective activity against irradiation induced renal injury due to its flavononid contents.

Protection of melatonin against long-term radon exposure-caused lung injury

Radon is one of the major pathogenic factors worldwide. Recently, epidemiological studies have suggested that radon exposure plays an important role in lung injury, which could further cause cancer. However, the toxic effects and underlying mechanism on lung injury are still not clear. Here, we identified the detailed toxic effects of long-term radon exposure. Specifically, the manifestations were inflammatory response and cell apoptosis in dose- and time-dependent manners. In detail, it caused the mitochondrial dysfunction and oxidative stress as determined by the abnormal levels of mitochondrial DNA copy number, adenosine triphosphate, mitochondrial membrane potential, superoxide dismutase, and cycloxygenase-2. Furthermore, we found that melatonin treatment ameliorated mitochondrial dysfunction and attenuated the levels of oxidative stress caused by long-term radon exposure, which could further inhibit the lung tissue apoptosis as determined by the decreased levels of cleaved caspase 3. Our study would provide potential therapeutic application of melatonin on lung tissue injury caused by long-term radon exposure.

Hypofractionated FLASH-RT as an Effective Treatment against Glioblastoma that Reduces Neurocognitive Side Effects in Mice

PURPOSE

Recent data have shown that single-fraction irradiation delivered to the whole brain in less than tenths of a second using FLASH radiotherapy (FLASH-RT), does not elicit neurocognitive deficits in mice. This observation has important clinical implications for the management of invasive and treatment-resistant brain tumors that involves relatively large irradiation volumes with high cytotoxic doses.

EXPERIMENTAL DESIGN

Therefore, we aimed at simultaneously investigating the antitumor efficacy and neuroprotective benefits of FLASH-RT 1-month after exposure, using a well-characterized murine orthotopic glioblastoma model. As fractionated regimens of radiotherapy are the standard of care for glioblastoma treatment, we incorporated dose fractionation to simultaneously validate the neuroprotective effects and optimized tumor treatments with FLASH-RT.

RESULTS

The capability of FLASH-RT to minimize the induction of radiation-induced brain toxicities has been attributed to the reduction of reactive oxygen species, casting some concern that this might translate to a possible loss of antitumor efficacy. Our study shows that FLASH and CONV-RT are isoefficient in delaying glioblastoma growth for all tested regimens. Furthermore, only FLASH-RT was found to significantly spare radiation-induced cognitive deficits in learning and memory in tumor-bearing animals after the delivery of large neurotoxic single dose or hypofractionated regimens.

CONCLUSIONS

The present results show that FLASH-RT delivered with hypofractionated regimens is able to spare the normal brain from radiation-induced toxicities without compromising tumor cure. This exciting capability provides an initial framework for future clinical applications of FLASH-RT.See related commentary by Huang and Mendonca, p. 662.

Resveratrol administration prevents radiation-related changes in metabolic profiles of hearts 20 weeks after irradiation of mice with a single 2 Gy dose

We aimed to evaluate whether resveratrol affects radiation-induced changes in metabolite profiles of the mouse heart. Hearts were irradiated in vivo with a single 2 Gy dose during the resveratrol administration and metabolite profiles of heart tissue were analyzed by the untargeted HR-MAS NMR approach twenty weeks after irradiation. The administration of resveratrol mitigated the radiation-induced decline in the content of choline-containing compounds and unsaturated lipids, which might reflect the stabilization of cell membrane structure against radiation-related damage. Results obtained with this mouse model suggest that the resveratrol supplementation may prevent metabolic changes related to radiation-induced damage in the heart.

Effects of phycocyanin on pulmonary and gut microbiota in a radiation-induced pulmonary fibrosis model

Objective

Radiation pneumonia and fibrosis are major clinical complications of radiotherapy for thoracic tumor patients, and may significantly reduce survival and quality of life. At present, no safe and effective radiation protection measures have been approved for clinical use. Phycocyanin, a protein responsible for photosynthesis from Spirulina, has been shown to have a variety of biological activities and to be beneficial for a variety of diseases, including pulmonary fibrosis. However, the preventive and protective effects of phycocyanin on radiation-induced pulmonary fibrosis have not been studied.

Design

X-ray single dose irradiation was used on the chest of mice to prepare a mouse model of pulmonary fibrosis, from which the effect of phycocyanin on pulmonary histopathologic change, pulmonary fibrosis, the microbiota in lung and gut, LPS, TNF-α, and IL-6 at different time after irradiation were evaluated.

Results

Phycocyanin alleviated the radiation-induced lung injury and reduced the level of inflammatory factors. Thorax irradiation led to the disorder in microbiota of the lung and gut. The variation trend of the diversity of the two tissues was opposite, but that of the microbiota composition was similar. The phycocyanin intervention regulated the composition of the lung and gut microbiota, transformed them into normal state, and reduced the level of LPS, which significantly reduced the abundance of inflammation-related bacteria, and increased the abundance of probiotics that produce short-chain fatty acids.

Conclusion

Phycocyanin could regulate the radiation-induced disorder in lung and gut microbiota of mice, and reduce the radiation-induced lung inflammation and fibrosis.

Sphingosine 1-phosphate protects against radiation-induced ovarian injury in female rats-impact on mitochondrial-related genes

The toxic effects of ionizing radiation on the gonads have been widely recognized. Sphingosine 1-phosphate (S1P) has a protective effect on ovarian injury, and although it is known that mitochondria are involved in this process, the specific mechanism is not fully understood. The present study analysed the changes in the serum AMH and ovarian histology in Sprague-Dawley female rats exposed to X-ray radiation only or co-administered with S1P. The mRNA expression profile of ovarian tissue was further analysed via next-generation sequencing and bioinformatics approaches to screen out candidate mitochondria-related genes. Finally, differentially expressed target genes were verified by real-time PCR. The results showed that ionizing radiation could reduce the serum AMH level, destroy ovarian structure and decrease the number of follicles in rats, while S1P administration significantly attenuated the impairment of ovarian function. Gene ontology (GO) and KEGG pathway analysis revealed that a variety of genes related to mitochondrial function were differentially expressed, and the protective effect of S1P on mitochondria was more obvious in the acute phase 24 h after radiation. The differentially expressed mitochondrial function-related genes associated with the protective effect of S1P were UQCRH, MICU2 and GPX4, which were subsequently verified by RT-PCR. Therefore, ionizing radiation has a significant effect on ovarian function, and S1P has a protective effect on radiation-induced ovarian injury, in which mitochondria may play an important role. This study sheds new light on the mechanism of radiation-induced ovarian injury and helps develop a novel potential strategy to control it.

Ionizing radiation induces BH4 deficiency by downregulating GTP-cyclohydrolase 1, a novel target for preventing and treating radiation enteritis

Radiation enteritis (RE) is a common side effect after radiotherapy for abdominal cancer. RE pathogenesis is complicated, with no drugs available for prevention or treatments. Intestinal ischemia is a key factor in the occurrence and development of enteritis. The effect of ionizing radiation (IR) on intestinal ischemia is unknown. Deficiency of tetrahydrobiopterin (BH4) produced by GTP-cyclohydrolase 1 (Gch1) is important in ischemic diseases. This study focused on the relationship of Gch1/BH4 between intestinal ischemia in radiation enteritis. BH4 levels were analyzed by high-performance liquid chromatography in humans and rats after radiotherapy. Intestinal blood perfusion was measured by laser doppler flow imaging. Vascular ring tests determined the diastolic functions of rat mesenteric arteries. Gene, protein, and immunohistochemical staining experiments and inhibitor interventions were used to investigate Gch1 and endothelial NOS (eNOS) in rat mesenteric arteries and endothelial cells. The results showed that IR decreased BH4 levels in patients and rats after radiotherapy and decreased intestinal blood perfusion in rats. The degree of change in intestinal ischemia was consistent with intestinal villus injury. Gch1 mRNA and protein levels and nitric oxide (NO) production significantly decreased, while eNOS uncoupling in arterial and vascular endothelial cells strongly increased. BH4 supplementation improved eNOS uncoupling and NO levels in vascular endothelia after IR. The results of this study showed that downregulation of Gch1 in intestinal blood vessels after IR is an important target in RE. BH4 supplementation may prevent intestinal ischemia and improve vascular endothelial function after IR. These findings have clinical significance for the prevention and treatment of RE.

A Comparison of Ramipril and Bevacizumab to Mitigate Radiation-Induced Brain Necrosis: An Experimental Study

BACKGROUND

Bevacizumab, an anti-vascular endothelial growth factor (VEGF) antibody, is a new treatment approach for radionecrosis. In our study, we compared the prophylactic and therapeutic usage of a promising agent, ramipril (an angiotensin-converting enzyme inhibitor), with that of bevacizumab for reducing radiation-induced brain injury after high-dose stereotactic radiosurgery (SRS).

METHODS

A total of 60 Wistar rats were used. The rats were irradiated with a single dose of 50 Gy using a Leksell Gamma Knife device. Bevacizumab and ramipril were administered in the prophylactic protocol (starting the first day of SRS) and in the therapeutic protocol (starting the fourth week of SRS). Their usage was continued until 12 weeks, and the right frontal lobes of the rats were examined histologically (hematoxylin and eosin stain) and immunohistochemically (hypoxia-inducible factor [HIF]-1α, VEGF, and CD31 antibody expression).

RESULTS

The expression of VEGF, HIF-1α, and CD31 had significantly increased at 12 weeks after SRS compared with the control group. The addition of bevacizumab or ramipril to SRS significantly mitigated the histological severity of radiation injury and the expression of VEGF, HIF-1α, and CD31. However, the prophylactic use of bevacizumab and ramipril seemed to be more effective than therapeutic administration. Our results also revealed that the greatest benefit was achieved with the use of prophylactic administration of bevacizumab compared with other treatment protocols.

CONCLUSIONS

Ramipril might be a promising agent for patients with radionecrosis. Clinical studies are required to investigate the effective and safe doses of ramipril, which is an inexpensive, well-tolerated drug that can cross the blood-brain barrier.

UPLC-MS-based serum metabolomics reveals protective effect of Ganoderma lucidum polysaccharide on ionizing radiation injury

ETHNOPHARMACOLOGICAL RELEVANCE

Ganoderma lucidum Polysaccharide (GLP),traditional Chinese medicine (TCM) active ingredient, has a long history and has good curative effects on radiation injury. However, the mechanism of GLP treating radiation injury has not been clearly elucidated.

THE AIM OF THE STUDY

This study was aimed to investigate the preventive effects of GLP on mice with radiation injury and to explore its mechanisms by serum metabolomics.

MATERIALS AND METHODS

Thirty mice were randomly divided into three groups,and namely 10 per group. The normal control group and the radiation model with normal saline and GLP group with GLP treatment (96 mg·kg-1) for 14 days. 2 h after 7th day after the intragastric administration, the model group and GLP group were subjected to whole body irradiation by X-rays except the normal control group. The peripheral blood WBC, RBC, HGB, PLT indicators.UPLC-Q-TOF-MS technique was used to analyze the serum of normal group, model group and GLP group, and to explore its potential key biomarkers and corresponding related metabolic pathways.

RESULTS

The number of peripheral blood leukocytes (WBC) in the radiation model group was lower than that in the GLP group and the number of platelets (PLT) in the GLP group was significantly higher than that in the model group.Combined with the methods of principal component analysis (PCA), projection to latent structure-discrimination analysis (PLS-DA), three group were clearly distinguished from each other and 18 metabolites were identified as the potential biomarkers in the GLP treated mice. The identified biomarkers indicated that there were perturbations of the taurine and hypotaurine metabolism and glycerophospholipid metabolism.

CONCLUSION

GLP can play a role in radiation protection by improving the expression of related potential biomarkers and related metabolic pathways in serum of radiation-induced mice.

Melatonin protects against apoptosis of megakaryocytic cells via its receptors and the AKT/mitochondrial/caspase pathway

Clinical studies have shown that melatonin lowers the frequency of thrombocytopenia in patients with cancer undergoing radiotherapy or chemotherapy. Here, we investigated the mechanisms by which melatonin promotes platelet formation and survival. Our results show that melatonin exerted protective effects on serum-free induced apoptosis of CHRF megakaryocytes (MKs). Melatonin promoted the formation of MK colony forming units (CFUs) in a dose-dependent manner. Using doxorubicin-treated CHRF cells, we found that melatonin rescued G2/M cell cycle arrest and cell apoptosis induced by doxorubicin. The expression of p-AKT was increased by melatonin treatment, an effect that was abolished by melatonin receptor blocker. In addition, we demonstrated that melatonin enhanced the recovery of platelets in an irradiated mouse model. Megakaryopoiesis was largely preserved in melatonin-treated mice. We obtained the same results in vivo from bone marrow histology and CFU-MK formation assays. Melatonin may exert these protective effects by directly stimulating megakaryopoiesis and inhibiting megakaryocyte apoptosis through activation of its receptors and AKT signaling.

Alpha-lipoic acid effectively attenuates ionizing radiation-mediated testicular dysfunction in rats: Crosstalk of NF-ĸB, TGF-β, and PPAR-ϒ pathways

Radiotherapy is one of the principal approaches employed in the treatment of pelvic cancers. Nevertheless, testicular dysfunction and infertility are among the most common adverse effects in young adult cancer survivors. Clinically, alpha-lipoic acid (LA) has been applied to improve the quality of sperm with a satisfactory effect. Therefore, the present study investigated the underlying mechanisms of the radioprotective effects of LA against testicular damage. Male Sprague-Dawley rats were exposed to 10 Gy of whole-body ϒ-radiation and LA (50 mg/kg, P.O.) was administered one week before and three days post-irradiation. LA showed remarkable capacity in preserving testicular tissue against radiation damage by improving histological and ultrastructural changes of disorganized seminiferous tubules, besides enhancing its diameter, germinal epithelial thickness, and Johnsen's score. Radiation instigated a significant decrease in sperm quality and quantity associated with depletion of serum testosterone levels, while the LA administration maintained spermatogenesis. Strikingly, LA exhibited antioxidant properties by restoring reduced glutathione levels and antioxidant enzyme activities such as catalase and glutathione-s-transferase, besides diminishing malondialdehyde levels in the testis of irradiated group. Furthermore, LA alleviated testicular inflammation through downregulation of nuclear factor-ĸB (NF-ĸB) expression with a subsequent reduction in interleukin (IL)-6 and cyclooxygenase-2 expression, accompanied by the augmented expression of the anti-inflammatory cytokine IL-10. Additionally, testicular fibrosis markers including Masson's trichrome and transforming growth factor (TGF)-β expression were noticeably declined in LA-treated irradiated rats, together with the upregulation of peroxisome proliferator-activated receptor-ϒ expression. Collectively, LA ameliorates radiation-mediated spermatogenesis-defects and testicular-damage via suppression of oxidative stress/NF-ĸB/TGF-β signaling.

Mitigation of Radiation-Induced Gastrointestinal System Injury by Melatonin: A Histopathological Study

AIMS

The current study aimed to investigate the potential role of melatonin in the mitigation of radiation-induced gastrointestinal injury.

BACKGROUND

Organs of the gastrointestinal system such as the intestines, colon, duodenum, ileum etc. are sensitive to ionizing radiation. Mitigation of radiation-induced gastrointestinal injury is an interesting topic in radiobiology and a life-saving approach for exposed persons after a radiation event or improving the quality of life of radiotherapy patients.

OBJECTIVE

The study aimed to find the possible mitigation effect of melatonin on radiation-induced damage to the small and large intestines.

METHODS

40 male mice were randomly assigned into four groups namely G1: control, G2: melatonin treatment, G3: whole-body irradiation, and G4: melatonin treatment after whole-body irradiation. A cobalt-60 gamma-ray source was used to deliver 7 Gy to the whole body. 100 mg/kg melatonin was administered orally 24 h after irradiation and continued for 5 days. Thirty days after irradiation, histopathological evaluations were performed.

RESULTS

The whole-body irradiation led to remarkable inflammation, villi shortening, apoptosis and damage to goblet cells of the small intestine. Furthermore, moderate to severe inflammation, apoptosis, congestion, crypt injury and goblet cell damage were reported for the colon. Treatment with melatonin after whole-body irradiation led to significant mitigation of radiation toxicity in both small and large intestines.

CONCLUSION

Melatonin could mitigate intestinal injury following whole-body exposure to radiation. Treatment with melatonin after an accidental exposure to radiation may increase survival via mitigation of damages to radiosensitive organs, including the gastrointestinal system.

Impact of zinc oxide nanoparticles on thioredoxin-interacting protein and asymmetric dimethylarginine as biochemical indicators of cardiovascular disorders in gamma-irradiated rats

Nanoparticle is a microscopic particle that has been existed in a wide range of biotechnological purposes. Zinc oxide nanoparticles (ZnO-NPs) have fewer environmental hazards and have shown positive impacts in the medical field. This work aimed to observe the effects of low and high doses of ZnO-NPs on heart injury induced by ionizing radiation (IR). Animals were irradiated by 8 Gy of gamma rays and ZnO-NPs (10 and 300 mg/Kg/day) were orally delivered to rats 1 hour after irradiation. Animals were dissected on 15th day postirradiation. Data showed that the oxidative damage resulted from radiation exposure, appeared by marked increments in the malondialdehyde (MDA) content and the level and protein expression of thioredoxin-interacting protein (TXNIP) with a noticeable decline in the level and expression of thioredoxin 1 (Trx-1) and thioredoxin reductase (TrxR), as well as glutathione (GSH) level and the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Moreover, radiation-induced inflammation, manifested by a noticeable elevation in the level of tumor necrotic factor-alpha (TNF-α), interleukin-18 (IL-18), and C-reactive protein (CRP). Additionally, endothelial dysfunction marked with a high level of asymmetric dimethylarginine (ADMA), total nitrite/nitrate (NOx), intercellular adhesion molecule 1 (ICAM-1), homocysteine (Hcy), creatine kinase (CK-MB), cardiac troponin-I (cTn-I), and lactate dehydrogenase (LDH). In addition, a decrease of zinc (Zn) level in the cardiac tissue was recorded. ZnO-NPs treatment (10 mg/kg) mitigated the oxidative stress and inflammation effects on the cardiovascular tissue through the positive modulations in the studied parameters. In contrast, ZnO-NPs treatment (300 mg/kg) induced cardiovascular toxicity of normal rats and elevated the deleterious effects of radiation. In conclusion, ZnO-NPs at a low dose could mitigate the adverse effects on cardiovascular tissue induced by radiation during its applications, while the high dose showed morbidity and mortality in normal and irradiated rats.

Resveratrol attenuates intestinal injury in irradiated rats via PI3K/Akt/mTOR signaling pathway

Radiation-induced enteritis is one of the greatest challenges in radiotherapy. The current study was designed to evaluate the ameliorative effect of resveratrol, which exhibits anti-inflammatory property, against radiation-induced intestinal injury in rats and to explore the underlying mechanism. Rats were exposed to a single dose of 5 Gy. Resveratrol (20 mg/kg/day) was orally administered to irradiated rats over 3 weeks. Results showed that resveratrol ameliorated the intestinal oxidative stress parameters; malondialdehyde (MDA) content, glutathione (GSH) level, and catalase (CAT) activity compared to irradiated group. Furthermore, resveratrol reduced the contents of inflammatory cytokines; tumor necrosis factor α (TNF-α), nuclear factor-kappa (NF-κB), and interleukin 1β (IL-1β) in intestine. Western blotting analysis revealed that resveratrol down-regulated the proteins expression of phosphoinositide 3-kinases (PI3K), protein kinase B (Akt) as well as the mammalian target of rapamycin (mTOR) in intestinal tissues of irradiated rats and thus reduced the inflammatory mediator production. These results were confirmed by histopathological investigation. In conclusion, resveratrol attenuated intestinal inflammation following irradiation via modulating PI3K/Akt/mTOR pathway and thereby could be a promising adjuvant in radiotherapy.

Radioprotection of EGCG based on immunoregulatory effect and antioxidant activity against 60Coγ radiation-induced injury in mice

Excessive reactive oxygen radicals (ROS) produced by ionizing radiation (IR) can cause human body to serious oxidative damage, leading to oxidation-reduction (REDOX) system imbalance and immune system damage. Here, the radioprotection of EGCG was studied through a model of oxidative damage in ⁶⁰Coγ radiation mice. Firstly, the weights and the main organs indexes of mice, including the liver index, spleen index and pancreas index, indicated preliminarily the safety and protection of EGCG. Then, the radioprotection of EGCG based on immune-regulation on radiation mice was further investigated. Results suggested that EGCG could prevent significantly the immune system damage caused by ⁶⁰Coγ via increasing the immune organ index, inducing the transformation of spleen cells into T- and B-lymphocytes, and enhancing the macrophage phagocytosis, compared with model group. In addition, EGCG could also protect spleens of radiation mice from ⁶⁰Coγ-induced the imbalance of REDOX system by enhancing the activities of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), increasing the level of glutathione (GSH), suppressing lipid peroxidation (Malondialdehyde, MDA). The antioxidant enzymes activities of serum and livers were also increased markedly. Taken together, our results indicated that EGCG possessed the excellent potential to serve as a natural radioprotector against IR-induced damage.

Cordycepin prevents radiation ulcer by inhibiting cell senescence via NRF2 and AMPK in rodents

The pathological mechanisms of radiation ulcer remain unsolved and there is currently no effective medicine. Here, we demonstrate that persistent DNA damage foci and cell senescence are involved in radiation ulcer development. Further more, we identify cordycepin, a natural nucleoside analogue, as a potent drug to block radiation ulcer (skin, intestine, tongue) in rats/mice by preventing cell senescence through the increase of NRF2 nuclear expression (the assay used is mainly on skin). Finally, cordycepin is also revealed to activate AMPK by binding with the α1 and γ1 subunit near the autoinhibitory domain of AMPK, then promotes p62-dependent autophagic degradation of Keap1, to induce NRF2 dissociate from Keap1 and translocate to the nucleus. Taken together, our findings identify cordycepin prevents radiation ulcer by inhibiting cell senescence via NRF2 and AMPK in rodents, and activation of AMPK or NRF2 may thus represent therapeutic targets for preventing cell senescence and radiation ulcer.

Design and synthesis a mitochondria-targeted dihydronicotinamide as radioprotector

Radiation-induced damage to the mitochondrial macromolecules and electron transfer chain (ETC), causing the generation of primary and secondary reactive oxygen (ROS) species. The continuous ROS production after radiation will trigger cell oxidative stress and ROS-mediated nucleus apoptosis and autophagy signaling pathways. Scavenging radiation-induced ROS effectively can help mitochondria to maintain their physiological function and relief cells from oxidative stress. Nicotinamide is a critical endogenous antioxidant helping to neutralize ROS in vivo. In this study, we designed and synthetized a novel mitochondrial-targeted dihydronicotinamide (Mito-N) with the help of mitochondrial membrane potential to enter the mitochondria and scavenge ROS. According to experiment results, Mito-N significantly increased cell viability by 30.75% by neutralizing the accumulated ROS and resisting DNA strands breaks after irradiation. Furthermore, the mice survival rate also improved with the treatment of Mito-N, by effectively ameliorating the hematopoietic system infliction under lethal dose irradiation.

Suplatast tosilate reduces radiation-induced lung injury in mice through suppression of oxidative stress

PURPOSE

Although radiotherapy is important in the treatment of malignant thoracic tumors, it has harmful effects on healthy tissues. We previously showed that suplatast tosilate, an anti-allergic agent, scavenged reactive oxygen species (ROS), including hydroxyl radicals. Because ROS-mediated oxidative stress is involved in radiation-induced lung injury, we hypothesized that suplatast tosilate could reduce radiation-induced lung injury via suppression of oxidative stress.

METHODS AND MATERIALS

Murine alveolar epithelial cells were irradiated with or without a medium containing suplatast tosilate in vitro to determine whether the agent had cytoprotective effects against radiation-induced injury. On the other hand, the thoracic region of C57BL/6 mice was exposed to a single irradiation dose of 15 Gy and the effects of suplatast tosilate were determined by a histological evaluation and assessment of the following parameters: cell number and inflammatory cytokine levels in bronchoalveolar lavage fluid, and oxidative stress markers and hydroxyproline content in pulmonary tissues.

RESULTS

Suplatast tosilate protected murine alveolar epithelial cells in vitro from irradiation-induced inhibition of cell proliferation, which was accompanied by the suppression of intracellular ROS and DNA double-strand breaks induced by irradiation. Oxidative stress markers and the levels of inflammatory and fibrogenic cytokines were upregulated in irradiated murine lungs in vivo. Suplatast tosilate suppressed both oxidative stress markers and the levels of cytokines, which resulted in reduced pulmonary fibrosis and clearly improved the survival rate after irradiation.

CONCLUSIONS

These findings demonstrate that suplatast tosilate could be a useful lung-protective agent that acts via suppression of oxidative stress associated with thoracic radiotherapy.

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.

Effects of Diet on Late Radiation Injuries in Rats

It has been speculated that the addition of antioxidants to diet could act as either radioprotectors or as mitigators of radiation injury. In preparation for studies of the mitigation efficacy of antioxidants, rats were placed on a modified version of AIN-76A, the diet typically used in such studies. This AIN-76A diet is refined and has no synthetic antioxidants or isoflavones. Compared to the natural-ingredient Teklad 8904 diet used in previous studies, use of the AIN-76A diet from 1-18 wk after irradiation significantly reduced injury in a radiation nephropathy model. A confirmation study included an additional arm in which the AIN-76A diet was started 2 wk prior to irradiation; again, the switch to AIN-76A postirradiation mitigated radiation nephropathy (p < 0.001), but switching to the AIN-76A diet preirradiation had no effect (p > 0.2). The two diets do not differ in salt content, but the AIN-76A diet is somewhat lower in protein (18% vs. 24%). The protein source (primarily soy in Teklad 8904 vs. casein in AIN-76A) might explain the effects. However, replacing the casein in AIN-76A with soy did not change the mitigation efficacy of the diet (p > 0.2 for comparison of the different AIN-76A diets). A similar study in a rat radiation pneumonitis model also suggested mitigation by postirradiation use of AIN-76A, although the effect was not statistically significant (p = 0.07). In conclusion, base diet alone can have biologically significant effects on organ radiosensitivity, but the mechanistic basis for the effect and its dependence of timing relative to irradiation are unclear.

Cardiac Remodeling and Reversible Pulmonary Hypertension During Pneumonitis in Rats after 13-Gy Partial-Body Irradiation with Minimal Bone Marrow Sparing: Effect of Lisinopril

Total-body irradiation causes acute and delayed toxicity to hematopoietic, pulmonary, cardiac, gastrointestinal, renal, and other organ systems. Angiotensin-converting enzyme inhibitors mitigate many of the delayed injuries to these systems. The purpose of this study was to define echocardiographic features in rats at two times after irradiation, the first before lethal radiation pneumonitis (50 d) and the second after recovery from pneumonitis but before lethal radiation nephropathy (100 d), and to determine the actions of the angiotensin-converting enzyme inhibitor lisinopril. Four groups of female WAG/RijCmcr rats at 11-12 wk of age were studied: nonirradiated, nonirradiated plus lisinopril, 13-Gy partial-body irradiation sparing one hind leg (leg-out partial-body irradiation), and 13-Gy leg-out partial-body irradiation plus lisinopril. Lisinopril was started 7 d after radiation. Echocardiograms were obtained at 50 and 100 d, and cardiac histology was assessed after 100 d. Irradiation without lisinopril demonstrated echocardiographic transient pulmonary hypertension by 50 d which was largely resolved by 100 d in survivors. Irradiated rats given lisinopril showed no increase in pulmonary artery pressures at 50 d but exhibited left ventricular remodeling. By 100 d these rats showed some signs of pulmonary hypertension. Lisinopril alone had no impact on echocardiographic end points at either time point in nonirradiated rats. Mild increases in mast cells and fibrosis in the heart were observed after 100 d following 13-Gy leg-out partial-body irradiation. These data demonstrate irradiation-induced pulmonary hypertension which was reversed in survivors of pneumonitis. Lisinopril modified cardiovascular remodeling to enhance survival in this model from 41% to 86% (p = 0.0013).

Delayed Effects of Acute Radiation Exposure (Deare) in Juvenile and Old Rats: Mitigation by Lisinopril

Our goal is to develop lisinopril as a mitigator of delayed effects of acute radiation exposure in the National Institute of Allergy and Infectious Diseases program for radiation countermeasures. Published studies demonstrated mitigation of delayed effects of acute radiation exposure by lisinopril in adult rats. However, juvenile or old rats beyond their reproductive lifespans have never been tested. Since no preclinical models of delayed effects of acute radiation exposure were available in these special populations, appropriate rat models were developed to test lisinopril after irradiation. Juvenile (42-d-old, prepubertal) female and male WAG/RijCmcr (Wistar) rats were given 13-Gy partial-body irradiation with only part of one hind limb shielded. Lethality from lung injury between 39-58 d and radiation nephropathy between 106-114 d were recorded. All irradiated-only juvenile rats were morbid from delayed effects of acute radiation exposure by 114 d, while lisinopril (24 mg m d) started 7 d after irradiation and continued improved survival to 88% (p = 0.0015, n ≥ 8/group). Old rats (>483-d-old, reproductively senescent) were irradiated with 13-Gy partial-body irradiation keeping part of one leg shielded and additionally shielding the head in some animals. Irradiated old females developed lethal nephropathy, and all became morbid by 170 d after irradiation, though no rats displayed lethal radiation pneumonitis. Similar results were observed for irradiated geriatric males, though 33% of rats remained alive at 180 d after irradiation. Lisinopril mitigated radiation nephropathy in old rats of both sexes. Finally, comparison of delayed effects of acute radiation exposure between irradiated juvenile, adult, and old rats showed younger rats were more sensitive to delayed effects of acute radiation exposure with earlier manifestation of injuries to some organs.

Role of betaine in liver injury induced by the exposure to ionizing radiation

Oxidative stress, apoptosis, and fibrosis may play a major role in the development of radiation-induced liver damage. Betaine, a native compound widely present in beetroot, was reported to possess hepato-protective properties. The objective of this study was to investigate the influence of betaine on radiation-induced liver damage. Animals were exposed to 9 Gy applied in 3 doses of 3 Gy/wk. Betaine (400 mg/kg/d), was orally supplemented to rats after the first radiation dose, and daily during the irradiation period. Animals were sacrificed 1 day after the last dose of radiation. The results showed that irradiation has induced oxidative stress in the liver denoted by a significant elevation in malondialdehyde, protein carbonyl, and 8-hydroxy-2-deoxyguanosine with a significant reduction in catalase activity and glutathione (GSH) content. The activity of the detoxification enzyme cytochrome P450 (CYP450) increased while GSH transferase (GSH-T) decreased. The activity of the apoptotic marker caspase-3 increased concomitant with increased hyaluronic acid, hydroxyproline, laminin (LN), and collagen IV. These alterations were associated with a significant increase of gamma-glutamyl transferase, alkaline phosphatase and alanine and aspartate aminotransferase markers of liver dysfunction. Betaine treatment has significantly attenuated oxidative stress, decreased the activity of CYP450, enhanced GSH-T, reduced the activity of caspase-3, and the level of fibrotic markers concomitant with a significant improvement of liver function. In conclusion, betaine through its antioxidant activity and by enhancing liver detoxification and reducing apoptosis may alleviate the progression of liver fibrosis and exert a beneficial impact on radiation-induced liver damage.

Heparin treatment mitigates radiation-induced oral mucositis in mice by interplaying with repopulation processes

PURPOSE

To investigate the mechanistic background of the muco-protective effect of systemic heparin treatment on the development of radiation-induced oral mucositis in mice.

MATERIALS AND METHODS

Fractionated irradiation was given to the snouts of male C3H/Neu mice over 2 weeks (10 × 3 Gy), either alone or in combination with daily subcutaneous application of unfractionated or low molecular weight heparin (40 or 200 I.U./mouse, respectively). Over this course of 14 days, groups of mice (n = 3) were sacrificed every second day, their tongues excised and processed for histological analysis. The epithelial radiation response with and without heparin treatment was evaluated in terms of tissue morphology, proliferation and expression of cell contact molecules.

RESULTS

Systemic treatment with heparins significantly reduced the cellular effects of irradiation to the oral epithelium. Heparin treated animals showed significantly higher total epithelial cell numbers and thickness throughout the study course. Bromodeoxyuridine (BrdU) incorporation analyses revealed that markedly more epithelial cells retained their proliferative capacity in the beginning of the first treatment week, but the proliferation of the mucosa was not stimulated during the rest of the study course. The expression of the adherens junction protein β‑catenin was slightly elevated in heparin treated animals, on day 2 the increase was statistically significant. The expression of e‑cadherin and occludin was mostly unaffected by the concomitant heparin treatment.

CONCLUSION

The findings of this study indicate an interplay of additional heparin treatment with the repopulation processes, leading to an earlier onset of this adaptive radiation response in oral mucosa. Importantly, we could demonstrate that the protective potential of heparin did not rely on stimulation of normal tissue proliferation. Since both heparin preparations are already approved for clinical use, they are considered as promising candidates for future clinical studies.

Biochemical and Histopathological Evaluation of the Radioprotective Effects of Melatonin Against Gamma Ray-Induced Skin Damage

BACKGROUND

Radiotherapy is one of the treatment methods for cancers using ionizing radiations. About 70% of cancer patients undergo radiotherapy. Radiation effect on the skin is one of the main complications of radiotherapy and dose limiting factor. To ameliorate this complication, we used melatonin as a radioprotective agent due to its antioxidant and anti-inflammatory effects, free radical scavenging, improving overall survival after irradiation as well as minimizing the degree of DNA damage and frequency of chromosomal abrasions.

METHODS

Sixty male Wistar rats were randomly assigned to 4 groups: control (C), melatonin (M), radiation (R) and melatonin + radiation (MR). A single dose of 30 Gy gamma radiation was exposed to the right hind legs of the rats while 40 mg/ml of melatonin was administered 30 minutes before irradiation and 2 mg/ml once daily in the afternoon for one month till the date of rat's sacrifice. Five rats from each group were sacrificed 4, 12 and 20 weeks after irradiation. Afterwards, their exposed skin tissues were examined histologically and biochemically.

RESULTS

In biochemical analysis, we found that malondialdehyde (MDA) levels significantly increased in R group and decreased significantly in M and MR groups after 4, 12, and 20 weeks, whereas catalase (CAT) and superoxide dismutase (SOD) activities decreased in the R group and increased in M and MR groups during the same time periods compared with the C group (p<0.05). Histopathological examination found there were statistically significant differences between R group compared with the C and M groups for the three different time periods (p<0.005, p<0.004 and p<0.004) respectively, while R group differed significantly with MR group (p<0.013). No significant differences were observed between C and M compared with MR group (p>0.05) at 4 and 20 weeks except for inflammation and hair follicle atrophy, while there were significant effects at 12 weeks (p<0.05).

CONCLUSION

Melatonin can be successfully used for the prevention and treatment of radiation-induced skin injury. We recommend the use of melatonin in optimal and safe doses. These doses should be administered over a long period of time for effective radioprotection and amelioration of skin damages as well as improving the therapeutic ratio of radiotherapy.

Thalidomide (THD) alleviates radiation induced lung fibrosis (RILF) via down-regulation of TGF-β/Smad3 signaling pathway in an Nrf2-dependent manner

Radiation-induced lung fibrosis (RILF) is a complication of radiotherapy in thoracic cancer patients. Thalidomide (THD) has a therapeutic effect on fibrotic and inflammatory disorders. The purpose of the current study was to investigate the therapeutic effect of THD on RILF in mice and better understand the underlying regulatory mechanisms of the therapeutic effect. We found that THD mitigated the fibrosis caused by irradiation in mice. The action of THD on RILF was related to the elevation of low levels reactive oxygen species (ROS), which inhibited the transforming growth factor‑β (TGF‑β)/Smad3 signaling pathway through activation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2). Analysis of the therapeutic effect of THD using Nrf2-/- mouse model confirmed the role of Nrf2 in vivo. In addition, no radioprotective effect of THD on thoracic cancer cell lines was observed. In conclusion, these data showed that THD attenuated RILF in mice, which was mediated by Nrf2-dependent down-regulation of the TGF-β/Smad3 pathway, suggesting THD as a potential novel agent for RILF prevention.

[RADIOPROTECTIVE ACTIVITY OF POLYMETOXY-LATED FLAVONOIDS OF CITRUS EXTRACT]

The aim of the study was to establish the radioprotective activity of citrus polymetoxylated flavonoids extract (CPMFE) on the X-irradiated rats. The experiments were carried out on white Wistar rats. Animals were irradiated with X rays in doses of 5 Gy and 7 Gy. The control group consisted the sham-irradiated rats. Part of animals of each group were treated with intramusculary injections of CPMFE (dose 30 mg/kg) during 7 days; blood was taken from the tail vein (0.5 ml) for detection of lipoperoxides (LOO.) content. On the 3rd day after irradiation 3 animals from each group were sacrificed (under ether anesthesia) and blood samples were taken for the study of antioxidant status. The activity of antioxidant enzymes (catalase (CAT) and superoxidedismutase (SOD)) was determined by the spectrophotometric method; the content of LOO.in the blood was determined by electron paramagnetic resonance (EPR) mrthod. In group of irradiated rats a sharp dose-dependent inactivation of blood antioxidant enzymes (SOD, CAT) and intensification of the lipid peroxidation were detected. The direct and feedback mechanism in the regulation of CAT and SOD activity, ensuring the implementation of antioxidant protection in the body was revealed. Under irradiation with 7Gy rapid death of animals (on 3-d day after irradiation the mortality of animals was 70%, and on the 5th day all died) were detected. During irradiation with dose 5 Gy the survival of animals increased (on the 8-th day after irradiation - 50% survival rate). CPMFE in dose-dependent manner supported the reduce the intensity of lipid peroxidation processes - at relatively low doses of radiation (5Gy) during the first 3 days the content of LOO.in the blood decreased insignificantly compared with indices in untreated animals, whereas with an increase in the dose of irradiation (7Gy) a statistically significant antiradical effect of CPMFE (a statistically significant decrease in the LOO. content) was detected. Under the effect of CPMFE in the blood of rats irradiated with a dose of 5 Gy and 7 Gy, the activity of CAT and SOD, not statistically significant tends to increase (more significant with a dose of 7 Gy). CPMFE did not affect the cumulative survival of animals irradiated with a dose of 5 Gy, but reduced the mortality of rats by 20% (on the 3rd day of irradiation), and contributed to an increase in the life expectancy of animals by 2 times (up to 7 days) in the case of dose 7 Gr. Based on the analysis of the research results, it can be assumed that under conditions of radiation damage, exogenous antioxidants synergistically with a dose-dependently activated endogenous non-enzymatic antioxidant system of the body (especially at 7Gy) contribute to the effective suppression of chain reactions of peroxidation, reduction of mortality and increase in life expectancy of animals.

Radio-Protective Effects of Octopus ocellatus Meat Consisted of a Plentiful Taurine Against Damages Caused by Gamma Ray Irradiation

Gamma ray irradiation causes immune suppressive responses by inducing oxidative stress such as reduction of cell viability and damages in immune cells. In this present study, we investigated whether Octopus ocellatus meet (OM) consisted of a plentiful taurine has protective effects against damages caused by oxidative stress in murine splenocytes. First of all, we prepared the aqueous extract from OM (OMA) and identified it contained a plentiful taurine content. The result also showed that OMA exhibited the antioxidant activity by scavenging DPPH and ABTS+ radicals and hydrogen peroxide. In addition, OMA improved the cell viability without cytotoxicity in gamma ray-irradiated murine splenocytes. Moreover, OMA significantly reduced the production of reactive oxygen species (ROS) in gamma ray-irradiated splenocytes. In further study, we identified that OMA protected zebrafish embryo via improving the reduced survival rate and decreasing the formation of deformity caused by the exposure of gamma ray irradiation. Also, OMA decreased the production of NO and ROS in gamma ray-irradiated zebrafish embryos as well as the induction of cell death. In these results, this study suggests that the consumption of taurine-rich foods, such as O. ocellatus, may be useful for the useful material for the protection against oxidative stress.

Localized Delivery of Amifostine Enhances Salivary Gland Radioprotection

Radiotherapy for head and neck cancers commonly causes damage to salivary gland tissue, resulting in xerostomia (dry mouth) and numerous adverse medical and quality-of-life issues. Amifostine is the only Food and Drug Administration-approved radioprotective drug used clinically to prevent xerostomia. However, systemic administration of amifostine is limited by severe side effects, including rapid decrease in blood pressure (hypotension), nausea, and a narrow therapeutic window. In this study, we demonstrate that retroductal delivery of amifostine and its active metabolite, WR-1065, to murine submandibular glands prior to a single radiation dose of 15 Gy maintained gland function and significantly increased acinar cell survival. Furthermore, in vivo stimulated saliva secretion was maintained in retrograde-treated groups at levels significantly higher than irradiated-only and systemically treated groups. In contrast to intravenous injections, retroductal delivery of WR-1065 or amifostine significantly attenuated hypotension. We conclude that localized delivery to salivary glands markedly improves radioprotection at the cellular level, as well as mitigates the adverse side effects associated with systemic administration. These results support the further development of a localized delivery system that would be compatible with the fractionated dose regimen used clinically.

Preclinical MRI: Studies of the irradiated brain

Radiation therapy (RT) plays a central role in the treatment of primary brain tumors. However, despite recent advances in RT treatment, local recurrences following therapy remain common. Radiation necrosis (RN) is a severe, late complication of radiation therapy in the brain. RN is a serious clinical problem often associated with devastating neurologic complications. Therapeutic strategies, including neuroprotectants, have been described, but have not been widely translated in routine clinical use. We have developed a mouse model that recapitulates all of the major pathologic features of late-onset RN for the purposes of characterizing the basic pathogenesis of RN, identifying non-invasive (imaging) biomarkers of RN that might allow for the radiologic discernment of tumor and RN, systematic testing of tumor and RN therapeutics, and exploring the complex interplay between RN pathogenesis and tumor recurrence. Herein, we describe the fundamental clinical challenges associated with RN and the progress made towards addressing these challenges by combining our novel mouse model of late-onset RN and magnetic resonance imaging (MRI). MRI techniques discussed include conventional T1- and T2-weighted imaging, diffusion-weighted imaging, magnetization transfer, and measures of tissue oxygenation. Studies of RN mitigation and neuroprotection are described, including the use of anti-VEGF antibodies, and inhibitors of GSK-3β, HIF-1α, and CXCR4. We conclude with some future perspectives on the irradiated brain and the study and treatment of recurrent tumor growing in an irradiated tumor microenvironment.

Hyaluronan as a mediator for the hepatoprotective effect of Diosmin/Hesperidin complex

Daflon is a phlebotonic drug widely used in chronic venous or lymphatic insufficiency. This study designed to investigate the relation of daflon with hyaluronan as a mediator for the hepatoprotective effect against Carbon tetrachloride (CCl4) and/or γ-radiation induced liver damage. Animals of this study were administered CCl4 (1 ml/kg b.wt.), exposed to γ-radiation (1Gy) and treated with daflon (100 mg/kg/day). Our results showed the ameliorative effect of daflon on cytochrome P450 (CYT P450), lipid peroxidation (MDA), liver enzymes (aspartate amino transferase; AST, alanine aminotransferase; ALT and gamma glutamyl transferase; γ-GT), antioxidant capacity (reduced glutathione; GSH and glutathione per oxidase; GPx), inflammatory markers (C-reactive protein; CRP and interlukin- 6; IL-6), alpha-fetoprotein (AFP) and extra cellular matrix proteins (hyaluronan; HA and hyaluronidase; HAase) which was supported by histopathological examination of liver sections compared to the damage induced in CCL4 and/or rats exposed to radiation. It could be concluded that the hepatoprotective effect of daflon is mediated via antioxidant and anti-inflammatory activity in addition to preserving native tissue hyaluronan by preventing its degradation.

A Metabolomic Serum Signature from Nonhuman Primates Treated with a Radiation Countermeasure, Gamma-tocotrienol, and Exposed to Ionizing Radiation

The search for and development of radiation countermeasures to treat acute lethal radiation injury has been underway for the past six decades, resulting in the identification of multiple classes of radiation countermeasures. However, to date only granulocyte colony-stimulating factor (Neupogen) and PEGylated granulocyte colony-stimulating factor (Neulasta) have been approved by the U.S. Food and Drug Administration for the treatment of hematopoietic acute radiation syndrome. Gamma-tocotrienol has demonstrated radioprotective efficacy in murine and nonhuman primate models. Currently, this agent is under advanced development as a radioprotector, and the authors are trying to identify its efficacy biomarkers. In this study, global metabolomic changes were analyzed using ultraperformance liquid chromatography quadrupole time-of-flight mass spectrometry. The pilot study using 16 nonhuman primates (8 nonhuman primates each in gamma-tocotrienol- and vehicle-treated groups), with samples obtained from gamma-tocotrienol-treated and irradiated nonhuman primates, demonstrates several metabolites that are altered after irradiation, including compounds involved in fatty acid beta-oxidation, purine catabolism, and amino acid metabolism. The machine-learning algorithm, Random Forest, separated control, irradiated gamma-tocotrienol-treated, and irradiated vehicle-treated nonhuman primates at 12 h and 24 h as evident in a multidimensional scaling plot. Primary metabolites validated included carnitine/acylcarnitines, amino acids, creatine, and xanthine. Overall, gamma-tocotrienol administration reduced high fluctuations in serum metabolite levels, suggesting an overall beneficial effect on animals exposed to radiation. This initial assessment also highlights the utility of metabolomics in determining underlying physiological mechanisms responsible for the radioprotective efficacy of gamma-tocotrienol.

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.

Ferulic acid protects against radiation-induced testicular damage in male rats: impact on SIRT1 and PARP1

Ionizing radiation is a major contributor to male infertility by destroying spermatogenesis. Therefore, the need for an effective radio-protective agent is evident. The objective of the present study was to investigate the potential radio-protective effect of ferulic acid (FA) on radiation-induced testicular damage. Mature male Sprague-Dawley rats were either exposed to a single-dose gamma radiation (5 Gy) and/or treated with FA (50 mg/kg), daily for 7 days before irradiation. Sirtuin1 (SIRT1), poly (ADP-ribose) polymerase 1 (PARP1), cytosolic calcium content, and the male reproductive functions (sperm head abnormality) as well as oxidative stress markers were assessed 7 days after irradiation. FA significantly maintained active spermatogenesis. Moreover, it reversed the oxidative stress effects of irradiation. The irradiated group showed marked elevation in both PARP1 expression and activity as well as in cytosolic calcium concentration, whereas SIRT1 activity and expression markedly decreased; in contrast, FA treatment prevented these alterations. Results of histopathological examination of testicular tissues indicated coincidence with those recorded by biochemical analyses. Our data show for the first time that FA had radio-protective effect against radiation-induced testicular damage. It improved spermatogenesis through increasing testicular SIRT1 and testosterone levels and decreasing oxidative stress, PARP1, and cytosolic calcium.

Progesterone Administration Fails to Protect Albino Male Rats against Photostress-Induced Retinal Degeneration

PURPOSE

Female patients show better recovery after brain injury and lower incidence of vascular diseases before menopause. The aim of this study was to test the protective effect of female sexual hormones against photostress-induced photoreceptor apoptosis.

METHODS

Five week old male albino Sprague-Dawley rats were injected intraperitoneally with progesterone (60 mg/kg body weight) for 4 days. The control group was injected with the vehicle only (benzyl alcohol). Both groups were halved and one was stressed with light (2700 lux for 24 hours) and the other remained under the original dim cyclic light condition. For functional evaluation, baseline electroretinograms (ERGs) were recorded 7 days before light stress, with follow-up ERGs 5 days after the cessation of light exposure. Animals were sacrificed and their eyes enucleated for histology.

RESULTS

Light exposure caused pronounced decrease in the ERG a- and b-wave amplitudes compared to controls. However, in the light-stressed group, the difference in retinal function between progesterone-treated and nontreated animals was not statistically significant. The thickness of the outer nuclear layer and the length of rod outer and inner segments were significantly reduced in the light-stressed group, indicating loss of rod photoreceptor cells. Progesterone had no neuroprotective effect on rod cell structure.

CONCLUSIONS

The administration of progesterone did not prove to be protective against excessive light-caused retinal degeneration on male albino rats. The role of other sexual steroids and their interaction need to be clarified.

A standardized Hippophae extract (SBL-1) counters neuronal tissue injuries and changes in neurotransmitters: implications in radiation protection

CONTEXT

Effects of a radioprotective, standardized leaf extract (code SBL-1) from traditional medicinal plant, sea buckthorn [Hippophae rhamnoides L. (Elaeagnaceae)], on neurotransmitters and brain injuries in rats showing radiation-induced conditioned taste aversion (CTA), are not known. Understanding CTA in rats is important because its process is considered parallel to nausea and vomiting in humans.

OBJECTIVE

This study investigated the levels of neurotransmitters, antioxidant defences and histological changes in rats showing radiation CTA, and their modification by SBL-1.

MATERIALS AND METHODS

The inbred male Sprague-Dawley rats (age 65 days, weighing 190 ± 10 g) were used. Saccharin-preferring rats were selected using standard procedure and divided into groups. Group I (untreated control) was administered sterile water, group II was 60Co-γ-irradiated (2 Gy), and group III was administered SBL-1 before irradiation. Observations were recorded up to day 5.

RESULTS

Irradiation (2 Gy) caused (i) non-recoverable CTA (≥ 64.7 ± 5.0%); (ii) degenerative changes in cerebral cortex, amygdala and hippocampus; (iii) increases in brain dopamine (DA, 63.4%), norepinephrine (NE, 157%), epinephrine (E, 233%), plasma NE (103%) and E (160%); and (iv) decreases in brain superoxide dismutase (67%), catalase (60%) and glutathione (51%). SBL-1 treatment (12 mg/kg body weight) 30 min before irradiation (i) countered brain injuries, (ii) reduced CTA (38.7 ± 3.0%, day 1) and (iii) normalized brain DA, NE, E, superoxide dismutase, catalase and CTA from day 3 onwards.

DISCUSSION AND CONCLUSION

Radiation CTA was coupled with brain injuries, disturbances in neurotransmitters and antioxidant defences. SBL-1 pretreatment countered these disturbances, indicating neuroprotective action.

Theaflavin ameliorates ionizing radiation-induced hematopoietic injury via the NRF2 pathway

It has been well established that reactive oxygen species (ROS) play a critical role in ionizing radiation (IR)-induced hematopoietic injury. Theaflavin (TF), a polyphenolic compound from black tea, has been implicated in the regulation of endogenous cellular antioxidant systems. However, it remains unclear whether TF could ameliorate IR-induced hematopoietic injury, particularly the hematopoietic stem cell (HSC) injury. In this study, we explored the potential role of TF in IR-induced HSC injury and the underlying mechanism in a total body irradiation (TBI) mouse model. Our results showed that TF improved survival of irradiated wild-type mice and ameliorated TBI-induced hematopoietic injury by attenuating myelosuppression and myeloid skewing, increasing HSC frequency, and promoting reconstitution of irradiated HSCs. Furthermore, TF inhibited TBI-induced HSC senescence. These effects of TF were associated with a decline in ROS levels and DNA damage in irradiated HSCs. TF reduced oxidative stress mainly by up-regulating nuclear factor erythroid 2-related factor 2 (NRF2) and its downstream targets in irradiated Lineage^-c-kit⁺ positive cells. However, TF failed to improve the survival, to increase HSC frequency and to reduce ROS levels of HSCs in irradiated Nrf2^-/- mice. These findings suggest that TF ameliorates IR-induced HSC injury via the NRF2 pathway. Therefore, TF has the potential to be used as a radioprotective agent to ameliorate IR-induced hematopoietic injury.

Progesterone improves neurocognitive outcomes following therapeutic cranial irradiation in mice

Despite improved therapeutic methods, CNS toxicity resulting from cancer treatment remains a major cause of post-treatment morbidity. More than half of adult patients with cranial irradiation for brain cancer develop neurobehavioral/cognitive deficits that severely impact quality of life. We examined the neuroprotective effects of the neurosteroid progesterone (PROG) against ionizing radiation (IR)-induced neurobehavioral/cognitive deficits in mice. Male C57/BL mice were exposed to one of two fractionated dose regimens of IR (3Gy×3 or 3Gy×5). PROG (16mg/kg; 0.16mg/g) was given as a pre-, concurrent or post-IR treatment for 14days. Mice were tested for short- and long-term effects of IR and PROG on neurobehavioral/cognitive function on days 10 and 30 after IR treatment. We evaluated both hippocampus-dependent and -independent memory functions. Locomotor activity, elevated plus maze, novel object recognition and Morris water maze tests revealed behavioral deficits following IR. PROG treatment produced improvement in behavioral performance at both time points in the mice given IR. Western blot analysis of hippocampal and cortical tissue showed that IR at both doses induced astrocytic activation (glial fibrillary acidic protein), reactive macrophages/microglia (CD68) and apoptosis (cleaved caspase-3) and PROG treatment inhibited these markers of brain injury. There was no significant difference in the degree of deficit in any test between the two dose regimens of IR at either time point. These findings could be important in the context of patients with brain tumors who may undergo radiotherapy and eventually develop cognitive deficits.

Rescue effects of ginger extract on dose dependent radiation-induced histological and biochemical changes in the kidneys of male Wistar rats

Radiation is an essential modality in the management of cancer therapy, but its acute and chronic side effects on the normal organs limit the helpfulness of radiotherapy. The deleterious effects of radiation begin with oxidative stress and inflammatory reaction to radiolytic hydrolysis and formation of free radicals. The aim of the current study was to investigate the effect of dose dependent whole body radiation exposure on histological and biochemical alterations in rat kidney. It was also planned to find out whether ginger extract mitigated the deleterious effects of different doses of radiation in rat kidney. Male Wistar rats were exposed to three doses (2, 4, and 8Gy) of γ- ray with or without a 10day pretreatment with ginger extract. After 10days of whole body γ- ray exposure, the results revealed proliferation of glomerular and tubular cells, fibrosis in glomerular and peritubular and a significant increase in 8-OHdG, CRP, cystatin C (in 8Gy), plasma urea and creatinine levels, as well as a significant decrease in total antioxidant capacity of radiation groups compared to those of the control group. Ginger extract administration once daily for 10 consecutive days before exposure to 2-4-8Gy radiotherapy, which ameliorated histological and biochemical alterations in kidneys of the rats entirely or partially compared to those in the ethanol group rats. These findings indicate that whole body exposure to radiation induces kidney damage through oxidative DNA damage and inflammatory reactions, and that these effects can be alleviated using ginger pretreatment as an antioxidant and anti-inflammatory agent.

GUCY2C Signaling Opposes the Acute Radiation-Induced GI Syndrome

High doses of ionizing radiation induce acute damage to epithelial cells of the gastrointestinal (GI) tract, mediating toxicities restricting the therapeutic efficacy of radiation in cancer and morbidity and mortality in nuclear disasters. No approved prophylaxis or therapy exists for these toxicities, in part reflecting an incomplete understanding of mechanisms contributing to the acute radiation-induced GI syndrome (RIGS). Guanylate cyclase C (GUCY2C) and its hormones guanylin and uroguanylin have recently emerged as one paracrine axis defending intestinal mucosal integrity against mutational, chemical, and inflammatory injury. Here, we reveal a role for the GUCY2C paracrine axis in compensatory mechanisms opposing RIGS. Eliminating GUCY2C signaling exacerbated RIGS, amplifying radiation-induced mortality, weight loss, mucosal bleeding, debilitation, and intestinal dysfunction. Durable expression of GUCY2C, guanylin, and uroguanylin mRNA and protein by intestinal epithelial cells was preserved following lethal irradiation inducing RIGS. Oral delivery of the heat-stable enterotoxin (ST), an exogenous GUCY2C ligand, opposed RIGS, a process requiring p53 activation mediated by dissociation from MDM2. In turn, p53 activation prevented cell death by selectively limiting mitotic catastrophe, but not apoptosis. These studies reveal a role for the GUCY2C paracrine hormone axis as a novel compensatory mechanism opposing RIGS, and they highlight the potential of oral GUCY2C agonists (Linzess; Trulance) to prevent and treat RIGS in cancer therapy and nuclear disasters. Cancer Res; 77(18); 5095-106. ©2017 AACR.