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Singh D, Malhotra P, Agarwal P, Kumar R. N-acetyl-l-tryptophan (NAT) ameliorates radiation-induced cell death in murine macrophages J774A.1 via regulating redox homeostasis and mitochondrial dysfunction. J Biochem Mol Toxicol 2024; 38:e23529. [PMID: 37702290 DOI: 10.1002/jbt.23529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 08/02/2023] [Accepted: 08/25/2023] [Indexed: 09/14/2023]
Abstract
Ionizing radiation interacts with the immune system and induces molecular damage in the cellular milieu by generating reactive oxygen species (ROS) leading to cell death. The present study was performed to investigate the protective efficacy of N-acetyl-L-tryptophan (NAT) against gamma-radiation-induced cell death in murine macrophage J774A.1 cells. The radioprotective efficacy of NAT was evaluated in terms of cell survivability, effect on antioxidant enzyme activity, and free radicals inhibition. Radioprotective efficacy of NAT pretreatment to irradiated cells was assessed via cell cycle progression, mitochondrial membrane potential (MMP) perturbation, and apoptosis regulation using flow cytometry. Results of the study demonstrated significant radioprotective efficacy (>80%) of NAT in irradiated cells as estimated by sulforhodamine B (SRB), MTT, and clonogenic assay. Significant (p < 0.001) reduction in ROS, xanthine oxidase, and mitochondrial superoxide levels along with increment in catalase, glutathione-s-transferase, glutathione, and ATPase activities in NAT pretreated plus irradiated cells was observed as compared to the gamma-irradiated cells. Further, significant (p < 0.001) stabilization of MMP and reduction in apoptosis was also observed in NAT pretreated plus irradiated cells as compared to irradiated cells that not pretreated with NAT. The current study demonstrates that NAT pretreatment to irradiated cells protects against gamma radiation-induced cell death by reducing oxidative stress, stabilizing MMP, and inhibiting apoptosis. These observations conclusively highlight the potential of developing NAT as a prospective radioprotective agent upon further validation using in-depth preclinical assessment in cellular and animal models.
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Affiliation(s)
- Darshana Singh
- Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Poonam Malhotra
- Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Prerna Agarwal
- Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Raj Kumar
- Institute of Nuclear Medicine and Allied Sciences, Delhi, India
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Wang S, Zhang Y, Meng W, Dong Y, Zhang S, Teng L, Liu Y, Li L, Wang D. The Involvement of Macrophage Colony Stimulating Factor on Protein Hydrolysate Injection Mediated Hematopoietic Function Improvement. Cells 2021; 10:2776. [PMID: 34685756 PMCID: PMC8534652 DOI: 10.3390/cells10102776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 11/16/2022] Open
Abstract
Protein hydrolysate injection (PH) is a sterile solution of hydrolyzed protein and sorbitol that contains 17 amino acids and has a molecular mass of 185.0-622.0 g/mol. This study investigated the effect of PH on hematopoietic function in K562 cells and mice with cyclophosphamide (CTX)-induced hematopoietic dysfunction. In these myelosuppressed mice, PH increased the number of hematopoietic cells in the bone marrow (BM) and regulated the concentration of several factors related to hematopoietic function. PH restored peripheral blood cell concentrations and increased the numbers of hematopoietic stem cells and progenitor cells (HSPCs), B lymphocytes, macrophages, and granulocytes in the BM of CTX-treated mice. Moreover, PH regulated the concentrations of macrophage colony stimulating factor (M-CSF), interleukin (IL)-2, and other hematopoiesis-related cytokines in the serum, spleen, femoral condyle, and sternum. In K562 cells, the PH-induced upregulation of hematopoiesis-related proteins was inhibited by transfection with M-CSF siRNA. Therefore, PH might benefit the BM hematopoietic system via the regulation of M-CSF expression, suggesting a potential role for PH in the treatment of hematopoietic dysfunction caused by cancer therapy.
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Affiliation(s)
- Shimiao Wang
- School of Life Sciences, Jilin University, Changchun 130012, China; (S.W.); (W.M.); (L.T.)
- Engineering Research Center of Chinese Ministry of Education for Edible and Medicinal Fungi, College of Plant Protection, Jilin Agricultural University, Changchun 130118, China; (Y.Z.); (Y.D.); (S.Z.); (Y.L.)
| | - Yuchong Zhang
- Engineering Research Center of Chinese Ministry of Education for Edible and Medicinal Fungi, College of Plant Protection, Jilin Agricultural University, Changchun 130118, China; (Y.Z.); (Y.D.); (S.Z.); (Y.L.)
| | - Weiqi Meng
- School of Life Sciences, Jilin University, Changchun 130012, China; (S.W.); (W.M.); (L.T.)
| | - Yihao Dong
- Engineering Research Center of Chinese Ministry of Education for Edible and Medicinal Fungi, College of Plant Protection, Jilin Agricultural University, Changchun 130118, China; (Y.Z.); (Y.D.); (S.Z.); (Y.L.)
| | - Sujie Zhang
- Engineering Research Center of Chinese Ministry of Education for Edible and Medicinal Fungi, College of Plant Protection, Jilin Agricultural University, Changchun 130118, China; (Y.Z.); (Y.D.); (S.Z.); (Y.L.)
| | - Lesheng Teng
- School of Life Sciences, Jilin University, Changchun 130012, China; (S.W.); (W.M.); (L.T.)
| | - Yang Liu
- Engineering Research Center of Chinese Ministry of Education for Edible and Medicinal Fungi, College of Plant Protection, Jilin Agricultural University, Changchun 130118, China; (Y.Z.); (Y.D.); (S.Z.); (Y.L.)
| | - Lanzhou Li
- School of Life Sciences, Jilin University, Changchun 130012, China; (S.W.); (W.M.); (L.T.)
- Engineering Research Center of Chinese Ministry of Education for Edible and Medicinal Fungi, College of Plant Protection, Jilin Agricultural University, Changchun 130118, China; (Y.Z.); (Y.D.); (S.Z.); (Y.L.)
| | - Di Wang
- School of Life Sciences, Jilin University, Changchun 130012, China; (S.W.); (W.M.); (L.T.)
- Engineering Research Center of Chinese Ministry of Education for Edible and Medicinal Fungi, College of Plant Protection, Jilin Agricultural University, Changchun 130118, China; (Y.Z.); (Y.D.); (S.Z.); (Y.L.)
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Malhotra P, Gupta AK, Singh D, Mishra S, Singh SK, Kumar R. Protection to immune system of mice by N-acetyl tryptophan glucoside (NATG) against gamma radiation induced immune suppression. Mol Immunol 2019; 114:578-590. [PMID: 31526941 DOI: 10.1016/j.molimm.2019.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 08/07/2019] [Accepted: 09/04/2019] [Indexed: 10/26/2022]
Abstract
Immune system is a critical modulator of radiation-induced biological effects. In this study, we have assessed protective potential of N-acetyl tryptophan glucoside (NATG) pre-treatment in bone marrow of gamma radiation challenged mice. Isolated bone marrow cells were analysed for cell cycle progression by flow cytometry, while various pro-/anti-inflammatory cytokine profiles were performed by ELISA method. Overall radioprotective ability of NATG in ensuring protection against gamma radiation-induced damage was assessed by evaluating whole body survival analysis and haematological studies on 9 Gy irradiated mice with/without NATG pre-treatment. Results exhibited pre-treatment with 150 mg/kg b.wt oral administration of NATG as most effective against 9 Gy radiation exposure. Moreover, NATG showed non-interfering effect on cell cycle progression in pre-treated irradiated mice group when compared to radiation alone group. In addition, cytokine expression analysis indicated significant (p > 0.05) elevation in levels of IFN-γ, IL-2, IL-12, IL-13 and IL-17 in NATG pre-treated irradiated mice in comparison to radiation alone group. On the contrary, NATG pre-treatment was observed to alleviate levels of TNF-α and IL-10 significantly (p < 0.05) in radiated group as compared to only irradiated mice group. Furthermore, NATG pre-treatment to 9 Gy radiation exposed mice aided in restoring their haematological parameters in terms of haemoglobin counts, RBC counts, WBC counts, hematocrit levels, platelets and granulocyte levels in comparison to irradiated alone mice, thus enhancing their immune system and contributing towards a better survival against gamma radiation-induced deleterious effects. Conclusively, this study highlights the potential of NATG as a prospective radiation countermeasure agent against ionizing radiation-induced assaults to the immune system.
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Affiliation(s)
- Poonam Malhotra
- Department of Radiation Biotechnology, Division of Radioprotective Drug Development and Research, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Ashutosh K Gupta
- Department of Radiation Biotechnology, Division of Radioprotective Drug Development and Research, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Darshana Singh
- Department of Radiation Biotechnology, Division of Radioprotective Drug Development and Research, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Saurabh Mishra
- Department of Radiation Biotechnology, Division of Radioprotective Drug Development and Research, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Shravan K Singh
- Department of Radiation Biotechnology, Division of Radioprotective Drug Development and Research, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Raj Kumar
- Department of Radiation Biotechnology, Division of Radioprotective Drug Development and Research, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India.
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Malhotra P, Singh D, Kumar R. In vitro stimulatory effect of N-acetyl tryptophan-glucopyranoside against gamma radiation induced immunosuppression. ENVIRONMENTAL TOXICOLOGY 2018; 33:305-314. [PMID: 29205752 DOI: 10.1002/tox.22517] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 11/13/2017] [Accepted: 11/17/2017] [Indexed: 06/07/2023]
Abstract
Radiation-induced manifestations like free radical burst, oxidative damage and apoptosis leading to cell death. In present study, N-acetyl tryptophan glucopyranoside (NATG) was assessed for its immune-radioprotective activities using J774A.1 cells. Clonogenic cell survival, cell cycle progression and cytokines i.e. IFN-γ, TNF-α, IL-2, IL-10, IL-12, IL-13 and IL-17A expression were evaluated in irradiated and NATG pretreated cells using clonogenic formation ability, flow cytometry and ELISA assay. Results indicated that 0.25μg/ml NATG exhibited maximum radioprotection against gamma-radiation (2Gy) without intervening in cell cycle progression. NATG pretreated (-2 h) plus irradiated cells showed significant elevation in IFN-γ (∼38.2%), IL-17A (∼53.7%) and IL-12 (∼58.8%) expression as compared to only irradiated cells. Conversely, significant decrease in TNF-α (∼21.6%), IL-10 (∼31.2%), IL-2 (∼23.7%) and IL-13 expression (∼17.8%) were observed in NATG pretreated plus irradiated cells as compared to irradiated cells. Conclusively, NATG pretreatment to irradiated J774A.1 cells, stimulate Th1 while diminish Th2 cytokines that contributes to radioprotection.
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Affiliation(s)
- Poonam Malhotra
- Division of Radioprotective Drug Development and Research, Radiation Biotechnology Group, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Darshana Singh
- Division of Radioprotective Drug Development and Research, Radiation Biotechnology Group, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Raj Kumar
- Division of Radioprotective Drug Development and Research, Radiation Biotechnology Group, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
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Malhotra P, Gupta AK, Singh D, Mishra S, Singh SK, Kumar R. N-Acetyl-tryptophan glucoside (NATG) protects J774A.1 murine macrophages against gamma radiation-induced cell death by modulating oxidative stress. Mol Cell Biochem 2018; 447:9-19. [PMID: 29372532 DOI: 10.1007/s11010-018-3289-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 01/18/2018] [Indexed: 12/18/2022]
Abstract
Immune system is amongst the most radiosensitive system to radiation-induced cellular and molecular damage. Present study was focused on the evaluation of radioprotective efficacy of a novel secondary metabolite, N-acetyl tryptophan glucoside (NATG), isolated from a radioresistant bacterium Bacillus sp. INM-1 using murine macrophage J774A.1 cells experimental model. Radioprotective efficacy of NATG against radiation-induced DNA damage and apoptosis was estimated using phosphatidyl-serine-externalization Annexin V-PI and Comet assay analysis. Radiation-induced cell death is the outcome of oxidative stress caused by free radicals. Therefore, perturbations in antioxidant enzymes i.e., superoxide dismutase (SOD), catalase, glutathione-s-transferase (GST) and GSH activities in irradiated and NATG pre-treated irradiated J774A.1 cells were studied. Results of the present study demonstrated that NATG pre-treated (0.25 µg/ml) irradiated (20 Gy) cells showed significant (p < 0.05) reduction in apoptotic cells index at 4-48 h as compared to radiation alone cells. Comet assay exhibited significant protection to radiation-induced DNA damage in J774A.1 cells. Significantly shortened DNA tail length, increased % Head DNA contents and lower olive tail moment was observed in NATG pre-treated irradiated cells as compared to radiation alone cells. Further, significant increase in catalase (~ 3.9 fold), SOD (67.52%), GST (~ 1.9 fold), and GSH (~ 2.5 fold) levels was observed in irradiated cells pre-treated with NATG as compared to radiation-alone cells. In conclusion, current study suggested that NATG pre-treatment to irradiated cells enhanced antioxidant enzymes in cellular milieu that may contribute to reduce oxidative stress and decrease DNA damage which resulted to significant reduction in the cell death of irradiated macrophages.
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Affiliation(s)
- Poonam Malhotra
- Division of Radioprotective Drug Development and Research, Department of Radiation Biotechnology, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Ashutosh K Gupta
- Division of Radioprotective Drug Development and Research, Department of Radiation Biotechnology, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Darshana Singh
- Division of Radioprotective Drug Development and Research, Department of Radiation Biotechnology, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Saurabh Mishra
- Division of Radioprotective Drug Development and Research, Department of Radiation Biotechnology, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Shravan K Singh
- Division of Radioprotective Drug Development and Research, Department of Radiation Biotechnology, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India
| | - Raj Kumar
- Division of Radioprotective Drug Development and Research, Department of Radiation Biotechnology, Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, India. .,Radiation Biotechnology Group, Radiation Biosciences Division, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi, 110054, India.
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Zhang H, Yan H, Ying J, Du L, Zhang C, Yang Y, Wang H, Wang H. Resveratrol ameliorates ionizing irradiation-induced long-term immunosuppression in mice. Int J Radiat Biol 2017; 94:28-36. [DOI: 10.1080/09553002.2018.1408976] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Heng Zhang
- Department of Oncology, Institute of Integrative Oncology, Tianjin Union Medical Center, Tianjin, China
| | - Hao Yan
- Department of Oncology, Institute of Integrative Oncology, Tianjin Union Medical Center, Tianjin, China
| | - Jianzi Ying
- Department of Oncology, Institute of Integrative Oncology, Tianjin Union Medical Center, Tianjin, China
| | - Liqing Du
- Institute of Radiation Medicine, Peking Union Medical College & Chinese Academy of Medical Sciences, Tianjin, China
| | - Chunze Zhang
- Department of Colorectal Surgery, Tianjin Union Medical Center, Tianjin, China
| | - Yiling Yang
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Huaqing Wang
- Department of Oncology, Institute of Integrative Oncology, Tianjin Union Medical Center, Tianjin, China
| | - Hui Wang
- Department of Oncology, Institute of Integrative Oncology, Tianjin Union Medical Center, Tianjin, China
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Malhotra P, Adhikari M, Mishra S, Singh S, Kumar P, Singh SK, Kumar R. N-acetyl tryptophan glucopyranoside (NATG) as a countermeasure against gamma radiation-induced immunosuppression in murine macrophage J774A.1 cells. Free Radic Res 2016; 50:1265-1278. [DOI: 10.1080/10715762.2016.1235788] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Poonam Malhotra
- Radiation Biotechnology Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Manish Adhikari
- Radiation Biotechnology Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Saurabh Mishra
- Radiation Biotechnology Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Sumit Singh
- Radiation Biotechnology Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Piyush Kumar
- School of Biotechnology, Gautam Buddha University, Greater Noida, Gautam Buddh Nagar, Uttar Pradesh, India
| | - Shravan Kumar Singh
- Radiation Biotechnology Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Raj Kumar
- Radiation Biotechnology Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
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Wang J, Zhang Y, Zhu Q, Liu Y, Cheng H, Zhang Y, Li T. Emodin protects mice against radiation-induced mortality and intestinal injury via inhibition of apoptosis and modulation of p53. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2016; 46:311-318. [PMID: 27525562 DOI: 10.1016/j.etap.2016.08.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 08/01/2016] [Accepted: 08/03/2016] [Indexed: 06/06/2023]
Abstract
The aim of this study was to explore the protective effect of emodin, a plant-derived anthraquinone, against gamma radiation-induced mortality and intestinal injury in mice, and to investigate the radioprotective molecular mechanism. C57BL/6 male mice were pre-treated with emodin for 7days via oral gavage before gamma radiation. We found that pretreatment with emodin prolonged mice survival time after 9Gy total body irradiation (TBI). Mice were sacrificed at 1 week after 7Gy TBI, we found that emodin attenuated intestinal morphological changes and increased villus height, crypt numbers, and reduced villus and crypt apoptosis as well as inhibited the expression of p53. MTT assay, flow cytometry, Hoechst 33258 staining, real-time PCR, and Western blotting indicated that emodin pretreatment can effectively increase human umbilical venous endothelial cells (HUVECs) viability and attenuate cell apoptosis; it also inhibited the expression of p53, Bax, and Caspase3 in HUVECs after irradiation. In summary, these results suggest the potential of emodin as an effective radioprotectant against radiation-induced intestinal injury.
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Affiliation(s)
- Jing Wang
- College of Pharmacology, Anhui University of Chinese Medicine, Hefei, Anhui 230012, China; Department of Pharmacology, Punan Hospital, Shanghai 200125, China
| | - Yue Zhang
- College of Pharmacology, Anhui University of Chinese Medicine, Hefei, Anhui 230012, China
| | - Qiuzhen Zhu
- Department of Pharmacology, College of Pharmacy, Second Military Medical University, Shanghai 200433, China
| | - Yulan Liu
- Department of Pharmacology, College of Pharmacy, Second Military Medical University, Shanghai 200433, China
| | - Hao Cheng
- College of Pharmacology, Anhui University of Chinese Medicine, Hefei, Anhui 230012, China
| | - Yuefan Zhang
- Department of Pharmacology, College of Pharmacy, Second Military Medical University, Shanghai 200433, China.
| | - Tiejun Li
- Department of Pharmacology, College of Pharmacy, Second Military Medical University, Shanghai 200433, China; College of Pharmacology, Anhui University of Chinese Medicine, Hefei, Anhui 230012, China; Department of Pharmacology, Punan Hospital, Shanghai 200125, China.
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Malhotra P, Adhikari M, Singh SK, Kumar R. N-acetyl tryptophan glucopyranoside (NATG) provides radioprotection to murine macrophage J774A.1 cells. Free Radic Res 2015; 49:1488-98. [DOI: 10.3109/10715762.2015.1095295] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Poonam Malhotra
- Radiation Biotechnology Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Manish Adhikari
- Radiation Biotechnology Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Shravan K. Singh
- Radiation Biotechnology Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Raj Kumar
- Radiation Biotechnology Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
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Wang H, Sethi G, Loke WK, Sim MK. Des-Aspartate-Angiotensin I Attenuates Mortality of Mice Exposed to Gamma Radiation via a Novel Mechanism of Action. PLoS One 2015; 10:e0138009. [PMID: 26378927 PMCID: PMC4574738 DOI: 10.1371/journal.pone.0138009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 08/24/2015] [Indexed: 01/09/2023] Open
Abstract
ACE inhibitors and ARBs (angiotensin receptor blockers) have been shown to attenuate radiation injuries in animal models of lethal gamma irradiation. These two classes of drug act by curtailing the actions of angiotensin II-linked inflammatory pathways that are up-regulated during gamma radiation in organ systems such as the brain, lung, kidney, and bone marrow. ACE inhibitors inhibit ACE and attenuate the formation of angiotensin II from angiotensin I; ARBs block the angiotensin AT1 receptor and attenuate the actions of angiotensin II that are elicited through the receptor. DAA-I (des-aspartate-angiotensin I), an orally active angiotensin peptide, also attenuates the deleterious actions of angiotensin II. It acts as an agonist on the angiotensin AT1 receptor and elicits responses that oppose those of angiotensn II. Thus, DAA-I was investigated for its anticipated radioprotection in gamma irradiated mice. DAA-I administered orally at 800 nmole/kg/day for 30 days post exposure (6.4 Gy) attenuated the death of mice during the 30-day period. The attenuation was blocked by losartan (50 nmole/kg/day, i.p.) that was administered sequential to DAA-I administration. This shows that the radioprotection was mediated via the angiotensin AT1 receptor. Furthermore, the radioprotection correlated to an increase in circulating PGE2 of surviving animals, and this suggests that PGE2 is involved in the radioprotection in DAA-I-treated mice. At the hematopoietic level, DAA-I significantly improved two syndromes of myelosuppression (leucopenia and lymphocytopenia), and mice pre-treated with DAA-I prior to gamma irradiation showed significant improvement in the four myelodysplastic syndromes that were investigated, namely leucopenia, lymphocytopenia, monocytopenia and thrombocytopenia. Based on the known ability of PGE2 to attenuate the loss of functional hematopoietic stem and progenitor cells in radiation injury, we hypothesize that PGE2 mediated the action of DAA-I. DAA-I completely attenuated the increase in circulating level of two inflammatory cytokines, TNFα and IL-6, in irradiated mice; and this shows that DAA-I exerted additional anti-inflammatory actions, which could also have contributed to its radioprotection. These findings show that DAA-I acts via a novel mechanism of action on the angiotensin AT1 receptor to specifically release PGE2, which mediates radioprotection in the gamma irradiated mice.
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Affiliation(s)
- Hong Wang
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Block MD11, 10 Medical Drive, Singapore, Singapore
| | - Gautam Sethi
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Block MD11, 10 Medical Drive, Singapore, Singapore
| | - Weng-Keong Loke
- Agent Diagnostic and Therapeutics Laboratory, Defence & Environmental Research Institute, DSO National Laboratories, 11 Stockport Road, Singapore, Singapore
| | - Meng-Kwoon Sim
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Block MD11, 10 Medical Drive, Singapore, Singapore
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