Gamma-tocotrienol, a radiation countermeasure, reverses proteomic changes in serum following total-body gamma irradiation in mice

Elliot Rosen, Oluseyi O Fatanmi, Stephen Y Wise, V Ashutosh Rao, Vijay K Singh

Sci Rep . 2022 Mar 1;12(1):3387. doi: 10.1038/s41598-022-07266-5.

Abstract

Radiological incidents or terrorist attacks would likely expose civilians and military personnel to high doses of ionizing radiation, leading to the development of acute radiation syndrome. We examined the effectiveness of prophylactic administration of a developmental radiation countermeasure, γ-tocotrienol (GT3), in a total-body irradiation (TBI) mouse model. CD2F1 mice received GT3 24 h prior to 11 Gy cobalt-60 gamma-irradiation. This dose of radiation induces severe hematopoietic acute radiation syndrome and moderate gastrointestinal injury. GT3 provided 100% protection, while the vehicle control group had 100% mortality. Two-dimensional differential in-gel electrophoresis was followed by mass spectrometry and Ingenuity Pathway Analysis (IPA). Analysis revealed a change in expression of 18 proteins in response to TBI, and these changes were reversed with prophylactic treatment of GT3. IPA revealed a network of associated proteins involved in cellular movement, immune cell trafficking, and inflammatory response. Of particular interest, significant expression changes in beta-2-glycoprotein 1, alpha-1-acid glycoprotein 1, alpha-2-macroglobulin, complement C3, mannose-binding protein C, and major urinary protein 6 were noted after TBI and reversed with GT3 treatment. This study reports the untargeted approach, the network, and specific serum proteins which could be translated as biomarkers of both radiation injury and protection by countermeasures.

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α-Tocopherol phosphate as a photosensitizer in the reaction of nucleosides with UV light: formation of 5,6-dihydrothymidine

Toshinori Suzuki, Chiaki Ono

Genes Environ . 2022 Feb 15;44(1):6. doi: 10.1186/s41021-022-00237-2.

Abstract

Introduction: α-Tocopherol phosphate, a natural water-soluble α-tocopherol analog, exists in biological tissues and fluids. Synthesized α-tocopherol phosphate is used as an ingredient of cosmetics.

Findings: When a neutral mixed solution of 2′-deoxycytidine, 2′-deoxyguanosine, thymidine, and 2′-deoxyadenosine was irradiated with UV light at wavelengths longer than 300 nm in the presence of α-tocopherol phosphate, thymidine was markedly consumed in an α-tocopherol phosphate dose-dependent manner, whereas other nucleosides only slightly decreased. Two major product peaks were detected in an HPLC chromatogram. The products were identified as diastereomers of 5,6-dihydrothymidine. The addition of radical scavengers had almost no effects on the generation of 5,6-dihydrothymidine, whereas the reactions of nucleosides other than thymidine were suppressed. Trolox, another water-soluble α-tocopherol analog, did not generate 5,6-dihydrothymidine, although all nucleosides were slightly consumed. When UV irradiation of thymidine with α-tocopherol phosphate was conducted in D2O, two deuterium atoms were added to 5 and 6 positions of thymidine with both syn and anti configurations. The ratio of syn and anti configurations alternated depending on pD of the solution.

Conclusions: The results indicate that α-tocopherol phosphate is a photosensitizer of nucleosides, especially thymidine, and that it introduces two hydrogen atoms to thymidine from H2O, generating 5,6-dihydrothymidine.

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Corrigendum: Gamma Tocotrienol Protects Mice From Targeted Thoracic Radiation Injury

Vidya P Kumar, Sasha Stone, Shukla Biswas, Neel Sharma, Sanchita P Ghosh

Front Pharmacol . 2021 Nov 29;12:785165. doi: 10.3389/fphar.2021.785165. eCollection 2021.

In the original article, we neglected to include the funder “US Department of Defense Threat Reduction Agency grant H.10016_09_AR_R to SG, administered by The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc.”

In the original article, we missed mentioning that we also used GT3 from American River Nutrition (Hadley, MA, United States). A correction has been made to Materials and Methods, GT3 Formulation:

“Pure GT3 was obtained from Yasoo Health Inc. (Johnson City, TN, United States) (Ghosh et al., 2009) and American River Nutrition (Hadley, MA, United States). GT3 and Tween80® (final concentration 5%) were dissolved separately in small volume of ethanol (to enable uniform mixing) and mixed together and then spin-dried under vacuum. Required volume of saline was added to the tube to achieve a final concentration of either 100 or 200 mg GT3 in 0.1 ml.”

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γ-Tocotrienol-Loaded Liposomes for Radioprotection from Hematopoietic Side Effects Caused by Radiotherapeutic Drugs

Sang-Gyu Lee, Teja Muralidhar Kalidindi, Hanzhi Lou, Kishore Gangangari, Blesida Punzalan, Ariana Bitton, Casey J Lee, Hebert A Vargas, Soobin Park, Lisa Bodei, Michael G Kharas, Vijay K Singh, Naga Vara Kishore Pillarsetty, Steven M Larson

J Nucl Med . 2021 Apr;62(4):584-590. doi: 10.2967/jnumed.120.244681. Epub 2020 Aug 21.

Abstract

With the successful development and increased use of targeted radionuclide therapy for treating cancer comes the increased risk of radiation injury to bone marrow-both direct suppression and stochastic effects, leading to neoplasia. Herein, we report a novel radioprotector drug, a liposomal formulation of γ-tocotrienol (GT3), or GT3-Nano for short, to mitigate bone marrow radiation damage during targeted radionuclide therapy. Methods: GT3 was loaded into liposomes using passive loading. 64Cu-GT3-Nano and 3H-GT3-Nano were synthesized to study the in vivo biodistribution profile of the liposome and GT3 individually. The radioprotection efficacy of GT3-Nano was assessed after acute 137Cs whole-body irradiation at a sublethal (4 Gy), a lethal (9 Gy), or a single high-dose administration of 153Sm-ethylenediamine-N,N,N’,N’-tetrakis(methylene phosphonic acid) (EDTMP). Flow cytometry and fluorescence microscopy were used to analyze hematopoietic cell population dynamics and the cellular site of GT3-Nano localization in the spleen and bone marrow, respectively. Results: Bone marrow uptake and retention (percentage injected dose per gram of tissue) at 24 h was 6.98 ± 2.34 for 64Cu-GT3-Nano and 7.44 ± 2.52 for 3H-GT3-Nano. GT3-Nano administered 24 h before or after 4 Gy of total-body irradiation (TBI) promoted rapid and complete hematopoietic recovery, whereas recovery of controls stalled at 60%. GT3-Nano demonstrated dose-dependent radioprotection, achieving 90% survival at 50 mg/kg against lethal 9-Gy TBI. Flow cytometry of the bone marrow indicated that progenitor bone marrow cells MPP2 and CMP were upregulated in GT3-Nano-treated mice. Immunohistochemistry showed that GT3-Nano accumulates in CD105-positive sinusoid epithelial cells. Conclusion: GT3-Nano is highly effective in mitigating the marrow-suppressive effects of sublethal and lethal TBI in mice. GT3-Nano can facilitate rapid recovery of hematopoietic components in mice treated with the endoradiotherapeutic agent 153Sm-EDTMP.

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Gamma Tocotrienol Protects Mice From Targeted Thoracic Radiation Injury

Vidya P Kumar, Sasha Stone, Shukla Biswas, Neel Sharma, Sanchita P Ghosh

Front Pharmacol . 2020 Nov 12;11:587970. doi: 10.3389/fphar.2020.587970. eCollection 2020.

Abstract

Radiation injury will result in multiorgan dysfuntion leading to multiorgan failure. In addition to many factors such as radiation dose, dose rate, the severity of the injury will also depend on organ systems which are exposed. Here, we report the protective property of gamma tocotrienol (GT3) in total as well as partial body irradiation (PBI) model in C3H/HeN male mice. We have carried out PBI by targeting thoracic region (lung-PBI) using Small Animal Radiation Research Platform, an X-ray irradiator with capabilities of an image guided irradiation with a variable collimator with minimized exposure to non-targeted tissues and organs. Precise and accurate irradiation of lungs was carried out at either 14 or 16 Gy at an approximate dose rate of 2.6 Gy/min. Though a low throughput model, it is amenable to change the field size on the spot. No damage to other non-targeted organs was observed in histopathological evaluation. There was no significant change in peripheral blood counts of irradiated mice in comparison to naïve mice. Femoral bone marrow cells had no damage in irradiated mice. As expected, damage to the targeted tissue was observed in the histopathological evaluation and non-targeted tissue was found normal. Regeneration and increase of cellularity and megakaryocytes on GT3 treatment was compared to significant loss of cellularity in saline group. Peak alveolitis was observed on day 14 post-PBI and protection from alveolitis by GT3 was noted. In irradiated lung tissue, thirty proteins were found to be differentially expressed but modulated by GT3 to reverse the effects of irradiation. We propose that possible mode of action of GT3 could be Angiopoietin 2-Tie2 pathway leading to AKT/ERK pathways resulting in disruption in cell survival/angiogenesis.

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Vitamin E reduces radiation injury of hippocampal neurons in mice by inhibiting ferroptosis

Chen Ren, Xuanzi Li, Shasha Du

Nan Fang Yi Ke Da Xue Xue Bao . 2020 Aug 30;40(8):1097-1102. doi: 10.12122/j.issn.1673-4254.2020.08.05.

Abstract

Objective: To explore the protective effect of vitamin E (VE) against radiation injury of hippocampal neurons in mice and explore the possible mechanism.

Methods: Cultured HT-22 and U251 cells with or without exposure to 8 Gy irradiation were treated with VE (200 μmol/L for 24 h), ferroptosis inhibitor (ferrostatin-1, 5 μmol/L for 24 h), apoptosis inhibitor (ZVAD-FMK, 2 μmol/L), or necroptosis inhibitor (100 μmol/L). MTT assay was used to evaluate the cell viability after the treatments, and reduced glutathione (GSH), malondialdehyde (MDA), lipid reactive oxygen species (lipid ROS), and intracellular iron ion levels were detected for assessment of ferroptosis. The mice exposed to 16 Gy irradiation with or without vitamin E (500 U/kg) treatment for 6 weeks were assessed for behavioral changes and cognitive functions using Morris water maze test.

Results: Treatment with VE significantly promoted the cell survival following irradiation in HT-22 cells (P < 0.05) but not in U251 cells (P > 0.05). Ferrostatin-1, but not ZVAD or the necroptosis inhibitor, promoted the survival of HT-22 cells following the irradiation. Exposure to irradiation significantly increased ferroptosis-related oxidative stress level in HT-22 cells, manifested by decreased GSH level and increased MDA, lipid ROS and intracellular iron ion levels (P < 0.05); treatment with VE and ferrostatin-1 both obviously reversed radiation-induced ferroptosis-related oxidative stress in the cells (P < 0.05). In Morris water maze test, the mice with radiation exposure showed obviously increased exploration time and distance (P < 0.05), which were significantly decreased after treatment with VE (P < 0.05).

Conclusions: Vitamin E reduces radiation injury by inhibiting ferroptosis in the hippocampal neurons in mice.

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Corneal UV Protective Effects of a Topical Antioxidant Formulation: A Pilot Study on In Vivo Rabbits

Marisa Palazzo, Francesco Vizzarri, Lubomir Ondruška, Michele Rinaldi, Luigi Pacente, Germano Guerra, Francesco Merolla, Ciro Caruso, Ciro Costagliola

Int J Mol Sci . 2020 Jul 30;21(15):E5426. doi: 10.3390/ijms21155426.

Abstract

This study aimed to evaluate the protective effect of a topical antioxidant and ultraviolet (UV) shielding action formulation containing riboflavin and D-α-tocopherol polyethylene glycol succinate (TPGS) vitamin E against corneal UV-induced damage in vivo rabbit eyes. In vivo experiments were performed using male albino rabbits, which were divided into four groups. The control group (CG) did not receive any UV irradiation; the first group (IG) was irradiated with a UV-B-UV-A lamp for 30 min; the second (G30) and third (G60) groups received UV irradiation for 30 and 60 min, respectively, and were topically treated with one drop of the antioxidant and shielding formulation every 15 min, starting one hour before irradiation, until the end of UV exposure. The cornea of the IG group showed irregular thickening, detachment of residual fragments of the Descemet membrane, stromal fluid swelling with consequent collagen fiber disorganization and disruption, and inflammation. The cornea of the G30 group showed edema, a mild thickening of the Descemet membrane without fibrillar collagen disruption and focal discoloration, or inflammation. In the G60 group, the cornea showed a more severe thickening, a more abundant fluid accumulation underneath the Descemet membrane with focal detachment, and no signs of severe tissue alterations, as were recorded in the IG group. Our results demonstrate that topical application of eye drops containing riboflavin and TPGS vitamin E counteracts UV corneal injury in exposed rabbits.

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The effect of aging and antioxidants on photoreactivity and phototoxicity of human melanosomes: An in vitro study

Magdalena M Olchawa, Grzegorz M Szewczyk, Andrzej C Zadlo, Olga I Krzysztynska-Kuleta, Tadeusz J Sarna

Pigment Cell Melanoma Res . 2020 Jul 23. doi: 10.1111/pcmr.12914. Online ahead of print.

Abstract

Aging may significantly modify antioxidant and photoprotective properties of melanin in retinal pigment epithelium (RPE). Here, photoreactivity of melanosomes (MS), isolated from younger and older human donors with and without added zeaxanthin and α-tocopherol, was analyzed by electron paramagnetic resonance oximetry, time-resolved singlet oxygen phosphorescence, and protein oxidation assay. The phototoxic potential of ingested melanosomes was examined in ARPE-19 cells exposed to blue light. Phagocytosis of FITC-labeled photoreceptor outer segments (POS) isolated from bovine retinas was determined by flow cytometry. Irradiation of cells fed MS induced significant inhibition of the specific phagocytosis with the effect being stronger for melanosomes from older than from younger human cohorts, and enrichment of the melanosomes with antioxidants reduced the inhibitory effect. Cellular protein photooxidation was more pronounced in samples containing older melanosomes, and it was diminished by antioxidants. This study suggests that blue light irradiated RPE melanosomes could induce substantial inhibition of the key function of the cells-their specific phagocytosis. The data indicate that while photoreactivity of MS and their phototoxic potential increase with age, they could be reduced by selected natural antioxidants.

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Tocol Prophylaxis for Total-body Irradiation: A Proteomic Analysis in Murine Model

Elliot Rosen, Oluseyi O Fatanmi, Stephen Y Wise, V Ashutosh Rao, Vijay K Singh

Health Phys . 2020 Jul;119(1):12-20. doi: 10.1097/HP.0000000000001221.

Abstract

The aim of this study was to analyze the changes in mouse jejunum protein expression in response to prophylactic administration of two promising tocols, γ-tocotrienol (GT3) and α-tocopherol succinate (TS), as radiation countermeasures before irradiation to elucidate the molecular mechanism(s) of their radioprotective efficacy. Mice were administered GT3 or TS (200 mg kg) subcutaneously 24 h prior to exposure to 11 Gy Co γ-radiation, a supralethal dose for mice. Jejunum was harvested 24 h post-irradiation. Results of the two-dimensional differential in-gel electrophoresis (2D-DIGE), coupled with mass spectrometry, and advanced bioinformatics tools suggest that the tocols have a corresponding impact on expression of 13 proteins as identified by mass spectrometry. Ingenuity Pathway Analysis (IPA) reveals a network of associated proteins involved in inflammatory response, organismal injury and abnormalities, and cellular development. Relevant signaling pathways including actin cytoskeleton signaling, RhoA signaling, and Rho family GTPase were identified. This study reveals the major proteins, pathways, and networks involved in preventing the radiation-induced injury in gut that may be contributing to enhanced survival.

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Deuteration of the Farnesyl Terminal Methyl Groups of δ-Tocotrienol and Its Effects on the Metabolic Stability and Ability of Inducing G-CSF Production

Xingui Liu, Zhengya Gao, Qiang Fu, Lin Song, Peiyi Zhang, Xuan Zhang, Howard Hendrickson, Peter A Crooks, Daohong Zhou, Guangrong Zheng

Bioorg Med Chem . 2020 Jun 1;28(11):115498. doi: 10.1016/j.bmc.2020.115498. Epub 2020 Apr 8.

Abstract

δ-tocotrienol (DT3), a member of vitamin E family, has been shown to have a potent radio-protective effect. However, its application as a radioprotectant is limited, at least in part, by its short plasma elimination half-life and low bioavailability. In an effort to increase the metabolic stability of DT3, a deuterium substituted DT3 derivative, d6-DT3, was designed and synthesized. d6-DT3 showed improved in vitro and in vivo metabolic stability compared to DT3. The unexpected lower potency of d6-DT3 in inducing granulocyte-colony stimulating factor (G-CSF) production in mouse revealed that the metabolite(s) of DT3 might play a major role in inducing G-CSF induction.

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