Advances of Amifostine in Radiation Protection: Administration and Delivery.

Amifostine (AMF, also known as WR-2721) is the only approved broad-spectrum small-molecule radiation protection agent that can combat hematopoietic damage caused by ionizing radiation and is used as an antitumor adjuvant and cell protector in cancer chemotherapy and radiotherapy. Amifostine is usually injected intravenously before chemotherapy or radiotherapy and has been used in the treatment of head and neck cancer. However, the inconvenient intravenous administration and its toxic side effects such as hypotension have severely limited its further application in clinic. In order to reduce the toxic and side effects, scientists are trying to develop a variety of drug administration methods and are devoted to developing a wide application of amifostine in radiation protection. This paper reviews the research progress of amifostine for radiation protection in recent years, discusses its mechanism of action, clinical application, and other aspects, with focus on summarizing the most widely studied amifostine injection administration and drug delivery systems, and explored the correlation between various administrations and drug efficacies.

Modulatory effect of amifostine (WR-1065) against genotoxicity and oxidative stress induced by methotrexate in human umbilical vein endothelial cells (HUVECs).

Amifostine is used in chemotherapy and radiotherapy as a cytoprotective adjuvant alongside DNA-binding chemotherapeutic agents. It functions by reducing free radicals and detoxifying harmful metabolites. Methotrexate, as an antimetabolite drug has been considered for treating various cancers and autoimmune diseases. However, the cytotoxic effects of methotrexate extend beyond tumor cells to crucial organs, including the heart. This study applied the HUVEC cell line as a reference in vitro model for researching the characteristics of vascular endothelium and cardiotoxicity. The current study aimed to assess amifostine's potential cytoprotective properties against methotrexate-induced cellular damage. Cytotoxicity was measured using the MTT assay. Apoptotic rates were evaluated by Annexin V-FITC/PI staining via flow cytometry. The genoprotective effect of amifostine was determined using the comet assay. Cells were exposed to various amifostine doses (10-200 µg/mL) and methotrexate (2.5 µM) in pretreatment culture condition. Methotrexate at 2.5 µM revealed cytotoxicity, apoptosis, oxidative stress and genotoxicity while highlighting amifostine's cyto/geno protective properties on HUVECs. Amifostine significantly decreased the levels of ROS and LPO while preserving the status of GSH and SOD activity. Furthermore, it inhibited genotoxicity (tail length, %DNA in tail, and tail moment) in the comet assay. Amifostine markedly attenuated methotrexate-induced apoptotic cell death (early and late apoptotic rates). These findings convey that amifostine can operate as a cytoprotectant agent.

Radioprotective role of amifostine on osteointegration of titanium implants in the tibia of rats.

BACKGROUND: Titanium is the most widely used metal for bone integration, especially for cancer patients receiving ionizing radiation. This study aimed to investigate the amifostine administration that would reduce the effects of radiation on bone healing and osseointegration in rat models. OBJECTIVES: It is aimed that the application of amifostine in rats receiving radiotherapy treatment will reduce the negative effects of ionizing radiation on the bone. METHODS: Thirty-five adult male Wistar rats were randomly divided into one healthy and four experimental groups. In three consecutive days, two experimental groups of rats (AMF-RT-IMP and RT-IMP) were exposed to radiation (15 Gy/3 fractions of 5 Gy each). Then the titanium implants were inserted into the left tibia. Before the radiotherapy process, a 200 mg/kg dose of amifostine (AMF) was administered to the rats in the AMF-IMP and AMF-RT-IMP groups. Twenty-eight days after the screw implant, all rats were sacrificed, and their blood samples and tibia bones were collected for analysis. RESULTS: The results indicated an accelerated bone formation and a more rapid healing process in the screw implants in the AMF-IMP, AMF-RT-IMP, and AMF-RT groups than in the RT-IMP group. Also, bone-implant contact area measurement and inflammation decreased with amifostine treatment in the implants subjected to irradiation (p < 0.05). CONCLUSIONS: The results obtained in the present study suggested that amifostine prevents the losses of bone minerals, bone integrity, and implant position from ionizing-radiation when given before exposure.

Ginkgo biloba extract attenuates cisplatin-induced renal interstitial fibrosis by inhibiting the activation of renal fibroblasts through down-regulating the HIF-1α/STAT3/IL-6 pathway in renal tubular epithelial cells.

BACKGROUND: Activation of renal fibroblasts into myofibroblasts plays an important role in promoting renal interstitial fibrosis (RIF). Ginkgo biloba extract (EGb) can alleviate RIF induced by cisplatin (CDDP). PURPOSE: To elucidate the effect of EGb treatment on cisplatin-induced RIF and reveal its potential mechanism. METHODS: The two main active components in EGb were determined by high-performance liquid chromatography (HPLC) analysis. Rats were induced by CDDP and then treated with EGb, 2ME2 (HIF-1α inhibitor) or amifostine. After HK-2 cells and HIF-1α siRNA HK-2 cells were treated with CDDP, EGb or amifostine, the conditioned medium from each group was cultured with NRK-49F cells. The renal function of rats was detected. The renal damage and fibrosis were evaluated by H&E and Masson trichrome staining. The IL-6 content in the cell medium was detected by ELISA. The expression levels of indicators related to renal fibrosis and signaling pathway were examined by western blotting and qRT-PCR. RESULTS: HPLC analysis showed that the contents of quercetin and kaempferol in EGb were 36.0 µg/ml and 45.7 µg/ml, respectively. In vivo, EGb and 2ME2 alleviated renal damage and fibrosis, as well as significantly decreased the levels of α-SMA, HIF-1α, STAT3 and IL-6 in rat tissues induced by CDDP. In vitro, the levels of HIF-1α, STAT3 and IL-6 were significantly increased in HK-2 cells and HIF-1α siRNA HK-2 cells induced by CDDP. Notably, HIF-1α siRNA significantly decreased the levels of HIF-1α, STAT3 and IL-6 in HK-2 cells, as well as the IL-6 level in medium from HK-2 cells. Additionally, the α-SMA level in NRK-49F cells was significantly increased after being cultured with conditioned medium from HK-2 cells or HIF-1α siRNA HK-2 cells exposed to CDDP. Furthermore, exogenous IL-6 increased the α-SMA level in NRK-49F cells. Importantly, the expression levels of the above-mentioned indicators were significantly decreased after the HK-2 cells and HIF-1α siRNA HK-2 cells were treated with EGb. CONCLUSION: This study revealed that EGb improves CDDP-induced RIF, and the mechanism may be related to its inhibition of the renal fibroblast activation by down-regulating the HIF-1α/STAT3/IL-6 pathway in renal tubular epithelial cells.

Effects of amifostine against blunt chest trauma-induced cardiac injury in rats.

BACKGROUND: This study aimed to examine whether two different doses of dexamethasone (DXM), which is a corticosteroid, and amifostine (AMI), which reduces cumulative tissue toxicity induced by cisplatin in advanced-stage cancer patients, have ameliorative effects on pathologic changes associated with cardiac contusion (CC) induced in rats. METHODS: Forty-two Wistar albino rats were equally divided into six groups (n=7): C, CC, CC+AMI 400, CC+AMI 200, CC+AMI+DXM, and CC+DXM. Tomography images and electrocardiographic analyzes were performed, mean arterial pressure was measured from the carotid artery, and blood and tissue samples were obtained for histopathological and biochemical analyses after trauma-induced CC. RESULTS: While the total oxidant status and disulfide parameters in the cardiac tissue and serum were significantly higher (p<0.05), the total antioxidant status, total thiol, and native thiol parameters were significantly lower (p<0.01) in rats with trauma-induced CC. The most frequently observed finding in the electrocardiography analyze was ST elevation. CONCLUSION: According to evaluation based on histological, biochemical, and electrocardiographic examinations, we believe that only 400 mg/kg dose of AMI or DXM can be effective in the treatment of myocardial contusion in rats. Evaluation based on histological findings.

Amifostine-Loaded Nanocarrier Traverses the Blood-Brain Barrier and Prevents Radiation-Induced Brain Injury.

Radiation-induced brain injury (RIBI) is a severe, irreversible, or even life-threatening cerebral complication of radiotherapy in patients with head and neck tumors, and there is no satisfying prevention and effective treatment available for these patients. Amifostine (AMF) is a well-known free radical scavenger with demonstrated effectiveness in preventing radiation-induced toxicity. However, the limited permeability of AMF across the blood-brain barrier (BBB) when administered intravenously reduces the effectiveness of AMF in preventing RIBI. Herein, we construct a nanoparticle (NP) platform for BBB delivery of AMF. AMF is conjugated with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-n-[poly(ethylene glycol)]-hydroxy succinamide [DSPE-PEG-NHS, PEG M 2000], and the product is DSPE-PEG-AMF. Then, the nanoparticles (DAPP NPs) were formed by self-assembly of poly(lactic-co-glycolic acid) (PLGA), DSPE-PEG-AMF, and polysorbate 80 (PS 80). PEG shields the nanoparticles from blood clearance by the reticuloendothelial system and lengthens the drug circulation time. PS 80 is used to encapsulate nanoparticles for medication delivery to the brain. The results of our study showed that DAPP NPs were able to effectively penetrate the blood-brain barrier (BBB) in healthy C57BL/6 mice. Furthermore, in a well-established mouse model of X-knife-induced brain injury, treatment with DAPP NPs (corresponding to 250 mg/kg AMF) was found to significantly reduce the volume of brain necrosis compared to mice treated with AMF (250 mg/kg). Importantly, the use of DAPP NPs was also shown to significantly mitigate the effects of radiation-induced neuronal damage and glial activation. This work presents a convenient brain-targeted AMF delivery system to achieve effective radioprotection for the brain, providing a promising strategy with tremendous clinical translation potential.

Repurposing of Various Current Medicines as Radioprotective Agents.

BACKGROUND: The side effects of ionising radiation include skin changes, dry mouth, hair loss, low blood count, and the mutagenic effect on normal cells when utilized in radiotherapy for cancer treatment. These radiations can cause damage to the cell membrane, lipids, proteins, and DNA and generate free radicals. Evidence reports stated that radiotherapy accounts for 17-19% of secondary malignancies, labelling this treatment option a double-edged sword. OBJECTIVE: Radioprotective molecules are used for mitigating radiotherapy's side effects. These agents show free radical scavenging, antioxidant, collagen synthesis inhibition, protease inhibition, immune stimulation, increased cytokine production, electron transfer, and toxicity reduction properties. The most frequently used amifostine has an array of cancer applications, showing multitarget action as nephroprotective to cisplatin and reducing the chances of xerostomia. Many other agents, such as metformin, edaravone, mercaptopropionylglycine, in specific diseases, such as diabetes, cerebral infarction, cystinuria, have shown radioprotective action. This article will discuss potentially repurposed radioprotectors that can be used in the clinical setting, along with a brief discussion on specific synthetic agents like amifostine and PrC-210. METHODS: Rigorous literature search using various electronic databases, such as PubMed, ScienceDirect, Scopus, EMBASE, Bentham Science, Cochrane Library, etc., was made. Peer-review research and review papers were selected, studied, reviewed, and analysed. CONCLUSION: Safety and risk-free treatment can be guaranteed with the repurposed agents. Agents like metformin, captopril, nifedipine, simvastatin, and various others have shown potent radioprotective action in various studies. This review compiled repurposed synthetic radioprotective agents.

The protective effects of red ginseng and amifostine against renal damage caused by ionizing radiation.

This study aimed to elucidate the effects of amifostine (ethyol) (AM), a synthetic radioprotector, and red ginseng (RG), a natural radioprotective agent, against the toxic effect of ionizing radiation (IR) on kidney tissues through changes in biochemical and histopathological parameters in addition to contributions to the use of amifostine and RG in clinical studies. Five groups were established: Group I (control, receiving only saline by gavage), Group II (IR only), and Group III (IR+AM, 200 mg/kg intraperitoneally (i.p.). Group IV (IR + RG, 200 mg/kg orally once a day for 4 weeks), and Group V (IR+RG+AM, 200 mg/kg orally once/day for 4 weeks before IR and 200 mg/kg AM administered (i.p.) 30 min before IR). All groups, except for the control group, were subject to 6-Gy whole-body IR in a single fraction. 24 h after irradiation, all animals were sacrificed under anesthesia. IR enhanced MDA, 8-OHdG, and caspase-3 expression while decreasing renal tissue GSH levels (p < .05). Significant numbers of necrotic tubules together with diffuse vacuolization in proximal and distal tubule epithelial cells were also observed. The examination also revealed substantial brush boundary loss in proximal tubules as well as relatively unusual glomerular structures. While GSH levels significantly increased in the AM, RG, and AM+RG groups, a decrease in KHDS, MDA, 8-OHdG, and caspase-3 expression was observed, compared to the group subject to IR only (p < .05). Therefore, reactive oxygen species-scavenging antioxidants may represent a promising treatment for avoiding kidney damage in patients receiving radiation.

Prevention of salivary gland dysfunction in patients treated with radioiodine for differentiated thyroid cancer: A systematic review of randomized controlled trials.

Introduction: Salivary gland dysfunction (e.g., sialadenitis and xerostomia) is the most common complication of radioactive iodine (RAI) therapy for differentiated thyroid cancer (DTC). Several methods have been used to reduce/prevent this adverse effect. We aimed to systematically review the effectiveness of non-pharmacological and pharmacological interventions in preventing RAI-induced salivary gland dysfunction in patients with DTC. Methods: A systematic review was conducted, according to PRISMA guidelines. The protocol was registered (PROSPERO: CRD42022295229). PubMed, Embase, Scopus, and the Cochrane Library electronic databases were searched from inception to November 2021. Inclusion criteria were randomized controlled trials of DTC patients who were older than 18 years and underwent RAI after thyroidectomy in which at least one studied group received an intervention to prevent salivary gland dysfunction. Results: Twelve studies (a total of 667 participants) were included. Among DTC patients who were treated with RAI, nonpharmacological treatment such as parotid gland massage and aromatherapy ameliorated salivary gland dysfunction. Antioxidants such as vitamin E and selenium demonstrated radioprotective effects on the salivary gland, while other antioxidants did not show radioprotective benefits. Vitamin C showed no significant effects on preventing salivary gland dysfunction. Amifostine had inconsistent outcomes among studies. Among cholinergic agonists, pilocarpine did not demonstrate the radioprotective effect on parotid glands, while bethanechol lowered salivary gland dysfunction. However, the negative results from pilocarpine may be explained by the strong sialorrheic effect of the Cincinnati regimen in both study arms. Conclusion: Among non-pharmacological and pharmacological methods, parotid gland massage, aromatherapy, vitamin E, selenium, amifostine, and bethanechol may have benefits in minimizing RAI-induced salivary gland dysfunction in patients with DTC. The results are limited by a small number of patients and should be confirmed in future larger randomized controlled trials. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=295229, PROSPERO, identifier CRD42022295229.

Could Amifostine Prevent Experimental Radiotherapy-Induced Acute Pericarditis?

BACKGROUND: Amifostine is a powerful antioxidant that is one of the documented three chemo-radio prototectants recommended for clinical use. There is no data exploring amifostine in prevention of acute pericardial damage. We aimed to investigate whether amifostine has protective effect against acute pericardial injury due to radiotherapy in an experimental rat model. METHODS: Twenty-four rats were divided into four groups: control group, radiotherapy-only group, amifostine-only group, radiotherapy+amifostine group. In groups receiving radiotherapy, hearts were irradiated with a Co 60 teletherapy device at a distance of 80 cm and 20 Gy at a depth of 2 cm. Thirty minutes before interventions, 200 mg/kg amifostine or same volume 0.9% NaCl were administered intraperitoneally. Subjects were sacrificed 24 hours after the procedure. Pericardial histopathological changes were investigated by light microscopy. RESULTS: There was focal inflammation of >= 50% in all rats exposed-to-radiotherapy. All groups receiving radiotherapy revealed a significant increase in pericardial inflammation compared to the groups that did not receive irradiation (p<0.05). There was no difference between the radiotherapy-only group and amifostine+radiotherapy group for pericardial inflammatory response (p>0.05). CONCLUSION: Acute pericarditis was detected in all rats receiving radiotherapy. There was no positive effect of amifostine administration before radiotherapy on acute pericardial inflammation.

Amifostine analog, DRDE-30, alleviates radiation induced lung damage by attenuating inflammation and fibrosis.

BACKGROUND: Radiotherapy of thoracic neoplasms and accidental radiation exposure often results in pneumonitis and fibrosis of lungs. Here, we investigated the potential of amifostine analogs: DRDE-07, DRDE-30, and DRDE-35, in alleviating radiation-induced lung damage. METHODS: C57BL/6 mice were exposed to 13.5 Gy thoracic irradiation, 30 min after intraperitoneal administration of the analogs, and assessed for modulation of the pathological response at 12 and 24 weeks. KEY FINDINGS: DRDE-07, DRDE-30 and DRDE-35 increased the survival of irradiated mice from 20% to 30%, 80% and 70% respectively. Reduced parenchymal opacity (X-ray CT) in the lungs of DRDE-30 pre-treated mice corroborated well with the significant decrease in Ashcroft score (p < 0.01). Two-fold increase in SOD and catalase activities (p < 0.05), coupled with a 50% increase in GSH content and a 60% decrease in MDA content (p < 0.05) suggested restoration of the antioxidant defence system. A 20% to 40% decrease in radiation-induced apoptotic and mitotic death in the lung tissue (micronuclei: p < 0.01), resulted in attenuated lung and vascular permeability (FITC-Dextran leakage) by 50% (p < 0.01), and a commensurate reduction (~50%) in leukocyte infiltration in the injured tissue (p < 0.05). DRDE-30 abrogated the activation of pro-inflammatory NF-κB and p38/MAPK signaling cascades, suppressing the release of pro-inflammatory cytokines (IL-1ß: p < 0.05; TNF-α: p < 0.05; IL-6: p < 0.05) and up-regulation of CAMs on the endothelial cell surface. Reduction in hydroxyproline content (p < 0.01) and collagen suggested inhibition of lung fibrosis which was associated with attenuation of TGF-ß/Smad pathway-mediated-EMT. CONCLUSION: DRDE-30 could be a potential prophylactic agent against radiation-induced lung injury.

Comparison of effects of dexmedetomidine and amifostine against X-ray radiation-induced parotid damage.

Radiotherapy can be employed as a therapeutic modality alone in the early stages of cancer and is used together with other treatments such as surgery and chemotherapy in more advanced stages. However, exposure to ionizing radiation in association with radiotherapy affects several organs in the head and neck and can give rise to early and late side effects. Exposure to ionizing radiation used in radiotherapy is known to cause cell damage by leading to oxygen stress through the production of free oxygen radicals (such as superoxide radicals, hydroxyl radical, hydrogen peroxide, and singlet oxygen), depending on the total radiation dosage, the fractionation rate, radiosensitivity, and linear energy transfer. The purpose of the present study was to determine the potential protective role of a powerful and highly selective α2-adrenoreceptor agonist with a broad pharmacological spectrum against salivary gland damage induced by ionizing radiation exposure. Forty Sprague-Dawley rats were divided into five groups-control, ionizing radiation, ionizing radiation + dexmedetomidine (100 µg/kg), ionizing radiation + dexmedetomidine (200 µg/kg), and ionizing radiation + amifostine (200 mg/kg). Following exposure to ionizing radiation, we observed necrosis, fibrosis, and vascular congestions in parotid gland epithelial cells. We also observed increases in malondialdehyde (MDA) and cleaved Caspase-3 levels and a decrease in glutathione (GSH). In groups receiving dexmedetomidine, we observed necrotic epithelial cells, fibrosis and vascular congestion in parotid gland tissue, a decrease in MDA levels, and an increase in GSH. Dexmedetomidine may be a promising antioxidant agent for the prevention of oxidative damage following radiation exposure.

The nephroprotective effect of amifostine in a cecal ligation-induced sepsis model in terms of oxidative stress and inflammation.

OBJECTIVE: Sepsis is responsible for more than 5 million deaths worldwide every year. The purpose of this study was to use amifostine to reduce acute kidney injury developing as a result of sepsis. MATERIALS AND METHODS: Thirty Sprague Dawley rats were divided into three equal groups - a healthy control group (Group 1), cecal ligation and puncture group (CLP, Group 2), and a CLP + amifostine (AMF) group receiving a total of 200 mg/kg AMF intraperitoneally (i.p.) 15 min before sepsis induction (Group 3). RESULTS: Total thiol levels decreased while malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), nuclear factor kappa B (NF-κB/p65), and interleukin (IL)-1ß, and IL-6 levels increased in the CLP group. We also observed degeneration in renal corpuscles, necrotic tubules, polymorphonuclear leukocyte inflammation, and vascular congestion. In the amifostine group, total thiol levels in tissue increased, while MDA, TNF-α, NF-кB/p65, IL-1ß, and IL-6 levels, necrotic renal tubules, and inflammation decreased. CONCLUSIONS: Amifostine prevented sepsis-related acute kidney injury by reducing inflammation and oxidative stress.

Radio-protective efficacy of Gymnema sylvestre on Pangasius sutchi against gamma (60Co) irradiation.

PURPOSE: Freshwater fish Pangasius sutchi was used in this study as a vertebrate model. We evaluated the induction of certain antioxidant enzymes in various vital organs. The radioprotective efficacy of Gymnema sylvestre leaves extract (GS) [25 mg/kg Body Weight (B.W)] and its bioactive compound Gymnemagenin (GG) [0.3 mg/kg B.W] was compared with Amifostine (Ami), the only radioprotector clinically approved by the US-FDA [Ami- 83.3 mg/kg B.W] against different doses of gamma radiation - 60Co (Lethal Dose: LD30-9.2 Gy, LD50-10.2 Gy and LD70-11.4 Gy). MATERIALS AND METHODS: This study was done via stress marker enzymes, cell cycle analysis (CCA) and DNA damage assay prediction with molecular docking, which are reported here for the first time. The results indicate an elevated LPO level and decreased level of CAT, SOD and GSH due to oxidative stress initiation by 60Co Ionizing Radiation (IR) on 4th day and slightly reduced on 32nd day while the reverse observed when the fishes were pretreated with Ami, GS and GG. Similarly, CCA and dead/live cells counts were conducted with pretreatment of Ami, GS and GG against 60Co IR dose (LD50-10.2 Gy). RESULTS: In CCA, G0/G1 phase was observed to be the highest in Ami and lowest in GG, against 60Co IR doses 10.2 Gy which was 51.76 ± 7.55. The dead cells range observed in pretreated group of Ami, GS and GG was lowest in Ami and highest in GG and live cells (highest in Ami and lowest in GG) as compared to 60Co IR group (86.43 ± 3.42 and 8.77 ± 5.95). Thus, antioxidant profile improvement by oxidative stress reduction and gradual progression of different phases of cell cycle except the apoptotic phase along with the live cells counts indicates that the radio-protective efficacy of GS is similar to Ami. CONCLUSION: Predictive assessment was carried out by docking of Ami, various components of GS with p53, NF-κß cells and Rad51 proteins structures responsible for CCA, apoptosis and repair mechanism. These structural proteins were docked with other structural proteins like USP7, TNF-α and partner and localizer of BRCA2 associated (PALB2/BRCA2) complex which made us perform these systemic efforts to find the functional activity of these known radio-protectants.

The role of amifostine in preventing radiotherapy induced testicular tissue damage in rats.

The germinal epithelium of the adult testis is susceptible to radiation induced damage. Amifostine is a drug used to prevent the side effects of radiotherapy (RT) and chemotherapy. We investigated the protective role of amifostine against RT induced damage to rat testis using the TUNEL assay. We used adult male rats divided equally into four groups: untreated control group; amifostine group, 200 mg/kg amifostine/day for 3 days; RT-saline group, 2 Gy/day local irradiation of testes for 3 days; RT-amifostine group, 2 Gy/day local irradiation of testes for 3 days plus 200 mg/kg amifostine 30 min before each irradiation. Four weeks after treatment, rats were sacrificed for histological examination and apoptosis was assessed using the TUNEL method. The TUNEL staining density was obtained by evaluating separate seminiferous tubules selected randomly from each section using the stereological fractionator method. Apoptosis in the seminiferous tubules in the control group and amifostine groups were evaluated as spontaneous. Frequent apoptosis was observed in the RT-saline group; a statistically significant difference was observed between the RT treated and untreated groups. Administration of amifostine 30 min before RT protected the testicular germ cells against apoptosis.

Radiation exposure induces cross-species temporal metabolic changes that are mitigated in mice by amifostine.

Exposure to acute, damaging radiation may occur through a variety of events from cancer therapy and industrial accidents to terrorist attacks and military actions. Our understanding of how to protect individuals and mitigate the effects of radiation injury or Acute Radiation Syndrome (ARS) is still limited. There are only a few Food and Drug Administration-approved therapies for ARS; whereas, amifostine is limited to treating low dose (0.7-6 Gy) radiation poisoning arising from cancer radiotherapy. An early intervention is critical to treat ARS, which necessitates identifying diagnostic biomarkers to quickly characterize radiation exposure. Towards this end, a multiplatform metabolomics study was performed to comprehensively characterize the temporal changes in metabolite levels from mice and non-human primate serum samples following γ-irradiation. The metabolomic signature of amifostine was also evaluated in mice as a model for radioprotection. The NMR and mass spectrometry metabolomics analysis identified 23 dysregulated pathways resulting from the radiation exposure. These metabolomic alterations exhibited distinct trajectories within glucose metabolism, phospholipid biosynthesis, and nucleotide metabolism. A return to baseline levels with amifostine treatment occurred for these pathways within a week of radiation exposure. Together, our data suggests a unique physiological change that is independent of radiation dose or species. Furthermore, a metabolic signature of radioprotection was observed through the use of amifostine prophylaxis of ARS.

Cyclophosphamide-Induced Inflammation of Taste Buds and Cytoprotection by Amifostine.

Taste buds in the oral cavity have a complex immune system regulating normal functions and inflammatory reactions. Cyclophosphamide (CYP), a chemotherapy drug, has wide-ranging disruptive effects on the taste system including loss of taste function, taste sensory cells, and capacity for taste cell renewal. In bladder epithelium, CYP also induces inflammation. To determine if CYP induces inflammation in taste buds, we used immunohistochemistry to examine tumor necrosis factor alpha (TNF-α) (a proinflammatory cytokine) expression over a 72-hour period. Expression of TNF-α increased in a subset of PLCß2 labeled (Type II) cells, but not SNAP-25 labeled (Type III) cells, between 8 and 24 h postinjection and declined slowly thereafter. This inflammatory response may play an important role in the disruptive effects of CYP on the taste system. Further, pretreatment with amifostine, a sulfhydryl drug known to protect normal tissues during chemo- or radiation therapy, reduced the amount of CYP-induced TNF-α expression in taste buds, suggesting this drug is capable of protecting normal cells of the taste system from adverse effects of CYP. Amifostine, used as a pretreatment to CYP and possibly other chemotherapy drugs, may offer clinical support for preventing negative side effects of chemotherapy on the taste system.

Radioprotective Effects of Kelulut Honey in Zebrafish Model.

Large doses of ionizing radiation can damage human tissues. Therefore, there is a need to investigate the radiation effects as well as identify effective and non-toxic radioprotectors. This study evaluated the radioprotective effects of Kelulut honey (KH) from stingless bee (Trigona sp.) on zebrafish (Danio rerio) embryos. Viable zebrafish embryos at 24 hpf were dechorionated and divided into four groups, namely untreated and non-irradiated, untreated and irradiated, KH pre-treatment and amifostine pre-treatment. The embryos were first treated with KH (8 mg/mL) or amifostine (4 mM) before irradiation at doses of 11 Gy to 20 Gy using gamma ray source, caesium-137 (137Cs). Lethality and abnormality analysis were performed on all of the embryos in the study. Immunohistochemistry assay was also performed using selected proteins, namely γ-H2AX and caspase-3, to investigate DNA damages and incidences of apoptosis. KH was found to reduce coagulation effects at up to 20 Gy in the lethality analysis. The embryos developed combinations of abnormality, namely microphthalmia (M), body curvature and microphthalmia (BM), body curvature with microphthalmia and microcephaly (BMC), microphthalmia and pericardial oedema (MO), pericardial oedema (O), microphthalmia with microcephaly and pericardial oedema (MCO) and all of the abnormalities (AA). There were more abnormalities developed from 24 to 72 h (h) post-irradiation in all groups. At 96 h post-irradiation, KH was identified to reduce body curvature effect in the irradiated embryos (up to 16 Gy). γ-H2AX and caspase-3 intensities in the embryos pre-treated with KH were also found to be lower than the untreated group at gamma irradiation doses of 11 Gy to 20 Gy and 11 Gy to 19 Gy, respectively. KH was proven to increase the survival rate of zebrafish embryos and exhibited protection against organ-specific abnormality. KH was also found to possess cellular protective mechanism by reducing DNA damage and apoptosis proteins expression.

Polycysteine as a new type of radio-protector ameliorated tissue injury through inhibiting ferroptosis in mice.

Amifostine has been the only small molecule radio-protector approved by FDA for decades; however, the serious adverse effects limit its clinical use. To address the toxicity issues and maintain the good potency, a series of modified small polycysteine peptides had been prepared. Among them, compound 5 exhibited the highest radio-protective efficacy, the same as amifostine, but much better safety profile. To confirm the correlation between the radiation-protective efficacy and the DNA binding capability, each of the enantiomers of the polycysteine peptides had been prepared. As a result, the L-configuration compounds had obviously higher efficacy than the corresponding D-configuration enantiomers; among them, compound 5 showed the highest DNA binding capability and radiation-protective efficacy. To our knowledge, this is the first study that has proved their correlations using direct comparison. Further exploration of the mechanism revealed that the ionizing radiation (IR) triggered ferroptosis inhibition by compound 5 could be one of the pathways for the protection effect, which was different from amifostine. In summary, the preliminary result showed that compound 5, a polycysteine as a new type of radio-protector, had been developed with good efficacy and safety profile. Further study of the compound for potential use is ongoing.

Effects of Amifostine Pre-treatment on MIRNA, LNCRNA, and MRNA Profiles in the Hypothalamus of Mice Exposed to 60Co Gamma Radiation.

There is increasing evidence that the expression of non-coding RNA and mRNA (messenger RNA) is significantly altered following high-dose ionizing radiation (IR), and their expression may play a critical role in cellular responses to IR. However, the role of non-coding RNA and mRNA in radiation protection, especially in the nervous system, remains unknown. In this study, microarray profiles were used to determine microRNA (miRNA), long non-coding RNA (lncRNA), and mRNA expression in the hypothalamus of mice that were pretreated with amifostine and subsequently exposed to high-dose IR. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed. We found that fewer miRNAs, lncRNAs, and mRNAs were induced by amifostine pre-treatment in exposed mice, which exhibited antagonistic effects compared to IR, indicating that amifostine attenuated the IR-induced effects on RNA profiles. GO and KEGG pathway analyses showed changes in a variety of signaling pathways involved in inflammatory responses during radioprotection following amifostine pre-treatment in exposed mice. Taken together, our study revealed that amifostine treatment altered or attenuated miRNA, lncRNA, and mRNA expression in the hypothalamus of exposed mice. These data provide a resource to further elucidate the mechanisms underlying amifostine-mediated radioprotection in the hypothalamus.