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Mothersill C, Seymour C, Cocchetto A, Williams D. Factors Influencing Effects of Low-dose Radiation Exposure. HEALTH PHYSICS 2024; 126:296-308. [PMID: 38526248 DOI: 10.1097/hp.0000000000001816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
ABSTRACT It is now well accepted that the mechanisms induced by low-dose exposures to ionizing radiation (LDR) are different from those occurring after high-dose exposures. However, the downstream effects of these mechanisms are unclear as are the quantitative relationships between exposure, effect, harm, and risk. In this paper, we will discuss the mechanisms known to be important with an overall emphasis on how so-called "non-targeted effects" (NTE) communicate and coordinate responses to LDR. Targeted deposition of ionizing radiation energy in cells causing DNA damage is still regarded as the dominant trigger leading to all downstream events whether targeted or non-targeted. We regard this as an over-simplification dating back to formal target theory. It ignores that last 100 y of biological research into stress responses and signaling mechanisms in organisms exposed to toxic substances, including ionizing radiation. We will provide evidence for situations where energy deposition in cellular targets alone cannot be plausible as a mechanism for LDR effects. An example is where the energy deposition takes place in an organism not receiving the radiation dose. We will also discuss how effects after LDR depend more on dose rate and radiation quality rather than actual dose, which appears rather irrelevant. Finally, we will use recent evidence from studies of cataract and melanoma induction to suggest that after LDR, post-translational effects, such as protein misfolding or defects in energy metabolism or mitochondrial function, may dominate the etiology and progression of the disease. A focus on such novel pathways may open the way to successful prophylaxis and development of new biomarkers for better risk assessment after low dose exposures.
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Affiliation(s)
- Carmel Mothersill
- Department of Biology, McMaster University, 1280 Main St., Hamilton, ON, Canada L8S 4L8
| | - Colin Seymour
- Department of Biology, McMaster University, 1280 Main St., Hamilton, ON, Canada L8S 4L8
| | - Alan Cocchetto
- The National CFIDS Foundation, 285 Beach Ave., Hull, MA 02045
| | - David Williams
- Cambridge University, The Old Schools, Trinity Lane, Cambridge CB2 1TN, United Kingdom
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Non-Targeted Effects of Synchrotron Radiation: Lessons from Experiments at the Australian and European Synchrotrons. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12042079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Studies have been conducted at synchrotron facilities in Europe and Australia to explore a variety of applications of synchrotron X-rays in medicine and biology. We discuss the major technical aspects of the synchrotron irradiation setups, paying specific attention to the Australian Synchrotron (AS) and the European Synchrotron Radiation Facility (ESRF) as those best configured for a wide range of biomedical research involving animals and future cancer patients. Due to ultra-high dose rates, treatment doses can be delivered within milliseconds, abiding by FLASH radiotherapy principles. In addition, a homogeneous radiation field can be spatially fractionated into a geometric pattern called microbeam radiotherapy (MRT); a coplanar array of thin beams of microscopic dimensions. Both are clinically promising radiotherapy modalities because they trigger a cascade of biological effects that improve tumor control, while increasing normal tissue tolerance compared to conventional radiation. Synchrotrons can deliver high doses to a very small volume with low beam divergence, thus facilitating the study of non-targeted effects of these novel radiation modalities in both in-vitro and in-vivo models. Non-targeted radiation effects studied at the AS and ESRF include monitoring cell–cell communication after partial irradiation of a cell population (radiation-induced bystander effect, RIBE), the response of tissues outside the irradiated field (radiation-induced abscopal effect, RIAE), and the influence of irradiated animals on non-irradiated ones in close proximity (inter-animal RIBE). Here we provide a summary of these experiments and perspectives on their implications for non-targeted effects in biomedical fields.
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Commonalities in the Features of Cancer and Chronic Fatigue Syndrome (CFS): Evidence for Stress-Induced Phenotype Instability? Int J Mol Sci 2022; 23:ijms23020691. [PMID: 35054876 PMCID: PMC8775947 DOI: 10.3390/ijms23020691] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/26/2021] [Accepted: 01/05/2022] [Indexed: 12/19/2022] Open
Abstract
Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) and Cancer-Related Fatigue (CRF) are syndromes with considerable overlap with respect to symptoms. There have been many studies that have compared the two conditions, and some of this research suggests that the etiologies of the conditions are linked in some cases. In this narrative review, CFS/ME and cancer are introduced, along with their known and putative mechanistic connections to multiple stressors including ionizing radiation. Next, we summarize findings from the literature that suggest the involvement of HPA-axis dysfunction, the serotonergic system, cytokines and inflammation, metabolic insufficiency and mitochondrial dysfunction, and genetic changes in CRF and CFS/ME. We further suspect that the manifestation of fatigue in both diseases and its causes could indicate that CRF and CFS/ME lie on a continuum of potential biological effects which occur in response to stress. The response to this stress likely varies depending on predisposing factors such as genetic background. Finally, future research ideas are suggested with a focus on determining if common biomarkers exist in CFS/ME patients and those afflicted with CRF. Both CFS/ME and CRF are relatively heterogenous syndromes, however, it is our hope that this review assists in future research attempting to elucidate the commonalities between CRF and CFS/ME.
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Apilan AG, Mothersill C. Targeted and Non-Targeted Mechanisms for Killing Hypoxic Tumour Cells-Are There New Avenues for Treatment? Int J Mol Sci 2021; 22:8651. [PMID: 34445354 PMCID: PMC8395506 DOI: 10.3390/ijms22168651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/07/2021] [Accepted: 08/09/2021] [Indexed: 11/25/2022] Open
Abstract
PURPOSE A major issue in radiotherapy is the relative resistance of hypoxic cells to radiation. Historic approaches to this problem include the use of oxygen mimetic compounds to sensitize tumour cells, which were unsuccessful. This review looks at modern approaches aimed at increasing the efficacy of targeting and radiosensitizing hypoxic tumour microenvironments relative to normal tissues and asks the question of whether non-targeted effects in radiobiology may provide a new "target". Novel techniques involve the integration of recent technological advancements such as nanotechnology, cell manipulation, and medical imaging. Particularly, the major areas of research discussed in this review include tumour hypoxia imaging through PET imaging to guide carbogen breathing, gold nanoparticles, macrophage-mediated drug delivery systems used for hypoxia-activate prodrugs, and autophagy inhibitors. Furthermore, this review outlines several features of these methods, including the mechanisms of action to induce radiosensitization, the increased accuracy in targeting hypoxic tumour microenvironments relative to normal tissue, preclinical/clinical trials, and future considerations. CONCLUSIONS This review suggests that the four novel tumour hypoxia therapeutics demonstrate compelling evidence that these techniques can serve as powerful tools to increase targeting efficacy and radiosensitizing hypoxic tumour microenvironments relative to normal tissue. Each technique uses a different way to manipulate the therapeutic ratio, which we have labelled "oxygenate, target, use, and digest". In addition, by focusing on emerging non-targeted and out-of-field effects, new umbrella targets are identified, which instead of sensitizing hypoxic cells, seek to reduce the radiosensitivity of normal tissues.
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Rusin A, Li M, Cocchetto A, Seymour C, Mothersill C. Radiation exposure and mitochondrial insufficiency in chronic fatigue and immune dysfunction syndrome. Med Hypotheses 2021; 154:110647. [PMID: 34358921 DOI: 10.1016/j.mehy.2021.110647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 04/19/2021] [Accepted: 07/25/2021] [Indexed: 12/13/2022]
Abstract
Chronic fatigue and Immune Dysfunction Syndrome (CFIDS) is a heterogeneous disease that may be promoted by various environmental stressors, including viral infection, toxin uptake, and ionizing radiation exposure. Previous studies have identified mitochondrial dysfunction in CFIDS patients, including modulation of mitochondrial respiratory chain activity, deletions in the mitochondrial genome, and upregulation of reactive oxygen species (ROS). This paper focuses on radiation effects and hypothesizes that CFIDS is primarily caused by stressor-induced mitochondrial metabolic insufficiency, which results in decreased energy production and anabolic metabolites required for normal cellular metabolism. Furthermore, tissues neighbouring or distant from directly perturbed tissues compensate for this dysfunction, which causes symptoms associated with CFIDS. This hypothesis is justified by reviewing the links between radiation exposure and CFIDS, cancer, immune dysfunction, and induction of oxidative stress. Moreover, the relevance of mitochondria in cellular responses to radiation and metabolism are discussed and putative mitochondrial biomarkers for CFIDS are introduced. Implications for diagnosis are then described, including a potential urine assay and PCR test for mitochondrial genome mutations. Finally, future research needs are offered with an emphasis on where rapid progress may be made to assist the afflicted.
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Affiliation(s)
- Andrej Rusin
- Department of Biology, McMaster University, Hamilton, ON Canada.
| | - Megan Li
- Department of Physics and Astronomy, McMaster University, Department of Physics and Astronomy, McMaster University, Hamilton, ON Canada
| | - Alan Cocchetto
- National CFIDS Foundation Inc., 103 Aletha Road, Needham, MA USA
| | - Colin Seymour
- Department of Biology, McMaster University, Hamilton, ON Canada
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Curtis JJ, Vo NTK, Seymour CB, Mothersill CE. 5-HT 2A and 5-HT 3 receptors contribute to the exacerbation of targeted and non-targeted effects of ionizing radiation-induced cell death in human colon carcinoma cells. Int J Radiat Biol 2020; 96:482-490. [PMID: 31846381 DOI: 10.1080/09553002.2020.1704911] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Purpose: Serotonin (5-HT) is implicated in the underlying mechanisms which mediate cell death following ionizing radiation exposure, however, effects appear to be cell type-dependent. We sought to further characterize the role of 5-HT and 5-HT receptors (5-HTRs) in the exacerbation of cell death following ionizing radiation exposure in human colon carcinoma cells.Materials and methods: We examined the clonogenic survival of colon carcinoma HCT116 cells treated with 5-HT and the selective 5-HTR antagonists ketanserin (5-HT2A) and ondansetron (5-HT3), following exposure to direct ionizing radiation and irradiated cell-conditioned medium (ICCM). The relative expression of these target receptors was measured using western blotting.Results: Western blotting results revealed that relative protein levels of the 5-HT2A and 5-HT3 receptors were similar. 5-HT concentration-dependent increases in cell death that occurred following direct ionizing radiation exposure were abolished by both 5-HTR antagonists. Death of nonirradiated cells recipient of ICCM was increased in a concentration-dependent manner by 5-HT when present during donor cell irradiation. Both 5-HTR antagonists completely abolished the increases in bystander-induced cell death generated by 5-HT. Finally, we show that exposure of cells to 5-HT prior to receipt of ICCM can also dictate the degree of bystander-induced cell death.Conclusions: Our findings demonstrate a definitive role for 5-HT in the exacerbation of cell death following ionizing radiation exposure in colon carcinoma cells and highlight 5-HTRs as potential markers for predicting cellular radiosensitivity.
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Affiliation(s)
- Jacob J Curtis
- Department of Biology, McMaster University, Hamilton, Canada
| | - Nguyen T K Vo
- Department of Biology, McMaster University, Hamilton, Canada
| | - Colin B Seymour
- Department of Biology, McMaster University, Hamilton, Canada
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Curtis JJ, Vo NTK, Seymour CB, Mothersill CE. Serotonin and 5-HT 3 receptors sensitize human skin cells to direct irradiation cell death but not to soluble radiation-induced bystander signals. ENVIRONMENTAL RESEARCH 2020; 180:108807. [PMID: 31629087 DOI: 10.1016/j.envres.2019.108807] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 10/05/2019] [Accepted: 10/06/2019] [Indexed: 06/10/2023]
Abstract
Ionizing radiation (IR) is an environmental carcinogen and the biological damages it elicits are mechanistically distinct between high and low doses. Non-targeted effects occurring in nonirradiated cells such as the radiation-induced bystander effect predominate at low doses of IR. However, the role of non-targeted effects in environmental radiation protection is often overlooked because the governing mechanisms are complex and multifactorial. An improved understanding of the signaling molecules and their capacity to sensitize specific cell types are essential in establishing environmental IR risks. In particular, serotonin (5-HT) has been identified to exacerbate both direct irradiation and bystander-induced cell death (CD) in certain cell types, although not all cell types are responsive to 5-HT in this respect. In this study, we further characterize the role of 5-HT and 5-HT receptors (5-HTR) in the amplification of CD following IR exposure in human keratinocytes. We examined the survival of HaCaT cells treated with 5-HT and the 5-HTR antagonists ketanserin (5-HT2A) and ondansetron (5-HT3) following exposure to direct IR and irradiated cell condition medium (ICCM). Nonirradiated cell survival was consistent with the vehicle control among 5-HT concentrations ranging from 0.001 to 100 μM. Significant 5-HT concentration-dependent increases in CD occurred following direct IR exposure. Nonirradiated ICCM-recipient CD was not altered by 5-HT (0.001-100 μM) when present during donor cell irradiation among all IR doses. Increases in direct irradiation CD evoked by 5-HT were significantly attenuated by ondansetron, blocking the effect of 5-HT, whereas ketanserin did not alter CD. Western blotting of these target 5-HTRs revealed protein expression of the 5-HT3 receptor, while the 5-HT2A receptor was not detected. We have demonstrated a definitive role for 5-HT in the exacerbation of CD following direct IR exposure and identified the 5-HT3 receptor as a potential target for ameliorating radiation damage in keratinocytes.
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Affiliation(s)
- Jacob J Curtis
- Department of Biology, McMaster University, Hamilton, Ontario, Canada.
| | - Nguyen T K Vo
- Department of Biology, McMaster University, Hamilton, Ontario, Canada.
| | - Colin B Seymour
- Department of Biology, McMaster University, Hamilton, Ontario, Canada.
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Perry KJ, Hamilton PW, Sonam S, Singh R, Henry JJ. The role of sensory innervation in cornea-lens regeneration. Dev Dyn 2019; 248:530-544. [PMID: 30993812 DOI: 10.1002/dvdy.42] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 03/27/2019] [Accepted: 04/08/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Numerous sensory nerves in the cornea contribute to normal tissue homeostasis. Interestingly, cells within the basal corneal epithelium can regenerate new lenses in the frog, Xenopus. In this study, we investigated whether cornea sensory nerves or their neuropeptides are important for supporting cornea-lens regeneration. RESULTS Attempts to sever the trigeminal nerve trunk, which provides sensory nerve branches to the cornea, did not inhibit lens regeneration. However, using this approach we found that it was not possible to completely disrupt sensory innervation, as these nerves are able to quickly regenerate back to the cornea. On the other hand, attenuation of neuropeptide levels with capsaicin was found to significantly inhibit lens regeneration, as visualized by a reduction of Substance P. These treatments also led to a reduction of cornea sensory innervation. Interestingly, inhibition of the Substance P-preferred receptor NK-1 with Spantide II did not affect lens-regeneration rates. CONCLUSIONS This study provides evidence that cornea nerves support cornea-lens regeneration, which could occur through the release of various neurotrophic factors. Substance P, however, does not appear to be the critical component of this signaling pathway. Further studies are needed to investigate what role other known neurotrophic factors may play in this process.
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Affiliation(s)
- Kimberly J Perry
- University of Illinois, Department of Cell and Developmental Biology, Urbana, Illinois
| | - Paul W Hamilton
- Illinois College, Department of Biology, Jacksonville, Illinois
| | - Surabhi Sonam
- University of Illinois, Department of Cell and Developmental Biology, Urbana, Illinois
| | - Ratnakar Singh
- University of Illinois, Department of Comparative Biosciences, Urbana, Illinois
| | - Jonathan J Henry
- University of Illinois, Department of Cell and Developmental Biology, Urbana, Illinois
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Karthik K, Rajan V, Pandey BN, Sivasubramanian K, Paul SF, Venkatachalam P. Direct and bystander effects in human blood lymphocytes exposed to 241Am alpha particles and the relative biological effectiveness using chromosomal aberration and micronucleus assay. Int J Radiat Biol 2019; 95:725-736. [DOI: 10.1080/09553002.2019.1589018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- K. Karthik
- Department of Human Genetics, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Vasumathy Rajan
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Badri N. Pandey
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, India
| | - K. Sivasubramanian
- Radiological Safety Division, Indira Gandhi Center for Atomic Research, Kalpakkam, India
| | - Solomon F.D. Paul
- Department of Human Genetics, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - P. Venkatachalam
- Department of Human Genetics, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
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Curtis JJ, Seymour CB, Mothersill CE. Cell Line-Specific Direct Irradiation and Bystander Responses are Influenced by Fetal Bovine Serum Serotonin Concentrations. Radiat Res 2018; 190:262-270. [PMID: 29963973 DOI: 10.1667/rr15072.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The radiation-induced bystander effect is mechanistically complex, involving many different signaling components. Serotonin, present in fetal bovine serum (FBS), has been implicated in the modulation of cellular responses to radiation. However, the role of this ubiquitous signaling molecule has yet to be elucidated with regard to cell line-specific radiation responses. In this study, cell survival was measured in HCT116 p53 wild-type (HCT116+/+) and HaCaT cell cultures treated with media containing serotonin-depleted FBS and compared to our standard FBS-supplemented media, using clonogenic assays. We utilized an enzyme-linked immunosorbent assay to quantify the difference (4.3 ± 1.3 ng/ml) in serotonin concentrations among the media. Serotonin-depleted media significantly reduced survival in both nonirradiated cell lines. Furthermore, we sought to determine the effects to cells in this media exposed to direct irradiation as well as bystander media from irradiated cells. Cell survival was significantly increased when HCT116+/+ cells were directly irradiated in serotonin-depleted media, while HaCaT cells showed no significant difference in survival between the media. Bystander investigations demonstrated that HCT116+/+ cells were only able to generate a bystander effect when cultured in standard media conditions containing greater serotonin levels. Conversely, HaCaT cells were unaffected by the different media in terms of producing a bystander response, generating bystander effects irrespective of the media. Previous research linking serotonin receptors to the bystander effect, together with our results, indicate that receptor heterogeneity among cell types may underlie serotonin sensitivity in direct irradiation and bystander responses through serotonin receptor-mediated cell signaling cascades.
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Affiliation(s)
- Jacob J Curtis
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Colin B Seymour
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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Szabo A, Gogolak P, Koncz G, Foldvari Z, Pazmandi K, Miltner N, Poliska S, Bacsi A, Djurovic S, Rajnavolgyi E. Immunomodulatory capacity of the serotonin receptor 5-HT2B in a subset of human dendritic cells. Sci Rep 2018; 8:1765. [PMID: 29379077 PMCID: PMC5788853 DOI: 10.1038/s41598-018-20173-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 01/15/2018] [Indexed: 12/14/2022] Open
Abstract
Serotonin is a monoamine neurotransmitter that signals through a wide array of receptors (5-HT1–7) many of which are also involved in immune processes. Dendritic cells (DCs) are crucial players in immune defense by bridging innate and adaptive immune responses via their vast repertoire of pattern recognition receptors and antigen-presenting capability. Although serotonin is known to influence immunity at many levels, cell type-specific expression and function of its receptors remains poorly understood. Here we aimed to study 5-HT1–7 expression and function in CD1a− and CD1a+ human monocyte-derived DCs (moDCs). We found that the 5-HT2B receptor-subtype is solely expressed by the inflammatory CD1a+ moDC subset. Specific 5-HT2B activation potently inhibited TLR2, TLR3, and TLR7/8-induced proinflammatory cytokine and chemokine (TNF-α, IL-6, IL-8, IP-10, IL-12) but not type I interferon-β responses. 5-HT2B agonism also interfered with the polarization of CD1a+ moDC-primed CD4+ T cells towards inflammatory Th1 and Th17 effector lymphocytes. Here we report the subset-specific expression and immunomodulatory function of 5-HT2B in human moDCs. Our results expand the biological role of 5-HT2B which may act not only as a neurotransmitter receptor, but also as an important modulator of both innate and adaptive immune responses.
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Affiliation(s)
- Attila Szabo
- NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Oslo, Norway. .,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway. .,Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
| | - Peter Gogolak
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gabor Koncz
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zsofia Foldvari
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Kitti Pazmandi
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Noemi Miltner
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Szilard Poliska
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Bacsi
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Srdjan Djurovic
- NORMENT, KG Jebsen Centre for Psychosis Research, Department of Clinical Science, University of Bergen, Bergen, Norway.,Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Eva Rajnavolgyi
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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Mothersill C, Rusin A, Fernandez-Palomo C, Seymour C. History of bystander effects research 1905-present; what is in a name? Int J Radiat Biol 2017; 94:696-707. [DOI: 10.1080/09553002.2017.1398436] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | - Andrej Rusin
- Department of Biology, McMaster University, Hamilton, Canada
| | | | - Colin Seymour
- Department of Biology, McMaster University, Hamilton, Canada
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13
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Vo NTK, Sokeechand BSH, Seymour CB, Mothersill CE. Characterizing responses to gamma radiation by a highly clonogenic fish brain endothelial cell line. ENVIRONMENTAL RESEARCH 2017; 156:297-305. [PMID: 28376375 DOI: 10.1016/j.envres.2017.03.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/25/2017] [Accepted: 03/27/2017] [Indexed: 06/07/2023]
Abstract
PURPOSE The clonogenic property and radiobiological responses of a fish brain endothelial cell line, eelB, derived from the American eel were studied. METHODS Clonogenic assays were performed to determine the plating efficiency of the eelB cells and to evaluate the clonogenic survival fractions after direct irradiation to low-dose low-LET gamma radiation or receiving irradiated cell conditioned medium in the bystander effect experiments. RESULT eelB had the second highest plating efficiency ever reported to date for fish cell lines. Large eelB macroscopic colonies could be formed in a short period of time and were easy to identify and count. Unlike with other fish clonogenic cell lines, which had a relatively slow proliferation profile, clonogenic assays with the eelB cells could be completed as early as 12 days in culture. After direct irradiation with gamma rays at low doses ranging from 0.1Gy to 5Gy, the dose-clonogenic survival curve of the eelB cell line showed a linear trend and did not develop a shoulder region. A classical radio-adaptive response was not induced with the clonogenic survival endpoint when the priming dose (0.1 or 0.5Gy) was delivered 6h before the challenge dose (3 or 5Gy). However, a radio-adaptive response was observed in progeny cells that survived 5Gy and developed lethal mutations. eelB appeared to lack the ability to produce damaging radiation-induced bystander signals on both eelB and HaCaT recipient cells. CONCLUSION eelB cell line could be a very useful cell model in the study of radiation impacts on the aquatic health.
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Affiliation(s)
- Nguyen T K Vo
- Radiation Sciences Program, School of Graduate and Postdoctoral Studies, McMaster University, Hamilton, ON, Canada.
| | - Bibi S H Sokeechand
- Radiation Sciences Program, School of Graduate and Postdoctoral Studies, McMaster University, Hamilton, ON, Canada
| | - Colin B Seymour
- Department of Biology, McMaster University, Hamilton, ON, Canada
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Weeks JC, Roberts WM, Robinson KJ, Keaney M, Vermeire JJ, Urban JF, Lockery SR, Hawdon JM. Microfluidic platform for electrophysiological recordings from host-stage hookworm and Ascaris suum larvae: A new tool for anthelmintic research. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2016; 6:314-328. [PMID: 27751868 PMCID: PMC5196495 DOI: 10.1016/j.ijpddr.2016.08.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/17/2016] [Accepted: 08/17/2016] [Indexed: 12/27/2022]
Abstract
The screening of candidate compounds and natural products for anthelmintic activity is important for discovering new drugs against human and animal parasites. We previously validated in Caenorhabditis elegans a microfluidic device (‘chip’) that records non-invasively the tiny electrophysiological signals generated by rhythmic contraction (pumping) of the worm's pharynx. These electropharyngeograms (EPGs) are recorded simultaneously from multiple worms per chip, providing a medium-throughput readout of muscular and neural activity that is especially useful for compounds targeting neurotransmitter receptors and ion channels. Microfluidic technologies have transformed C. elegans research and the goal of the current study was to validate hookworm and Ascaris suum host-stage larvae in the microfluidic EPG platform. Ancylostoma ceylanicum and A. caninum infective L3s (iL3s) that had been activated in vitro generally produced erratic EPG activity under the conditions tested. In contrast, A. ceylanicum L4s recovered from hamsters exhibited robust, sustained EPG activity, consisting of three waveforms: (1) conventional pumps as seen in other nematodes; (2) rapid voltage deflections, associated with irregular contractions of the esophagus and openings of the esophogeal-intestinal valve (termed a ‘flutter’); and (3) hybrid waveforms, which we classified as pumps. For data analysis, pumps and flutters were combined and termed EPG ‘events.’ EPG waveform identification and analysis were performed semi-automatically using custom-designed software. The neuromodulator serotonin (5-hydroxytryptamine; 5HT) increased EPG event frequency in A. ceylanicum L4s at an optimal concentration of 0.5 mM. The anthelmintic drug ivermectin (IVM) inhibited EPG activity in a concentration-dependent manner. EPGs from A. suum L3s recovered from pig lungs exhibited robust pharyngeal pumping in 1 mM 5HT, which was inhibited by IVM. These experiments validate the use of A. ceylanicum L4s and A. suum L3s with the microfluidic EPG platform, providing a new tool for screening anthelmintic candidates or investigating parasitic nematode feeding behavior. Pharyngeal pumping in nematodes generates an electropharyngeogram (EPG). The EPG provides a readout of the electrical activity of neurons and muscles. A microfluidic platform for recording EPGs was validated in parasitic nematodes. EPG activity and drug responses were characterized in host-stage larvae. Microfluidic EPG recordings provide a powerful new tool for anthelmintic research.
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Affiliation(s)
- Janis C Weeks
- Institute of Neuroscience and African Studies Program, University of Oregon, 1254 University of Oregon, Eugene, OR 97403-1254, USA.
| | - William M Roberts
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR 97403-1254, USA.
| | - Kristin J Robinson
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR 97403-1254, USA.
| | - Melissa Keaney
- Department of Microbiology, Immunology, and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA.
| | - Jon J Vermeire
- Center for Discovery and Innovation in Parasitic Diseases, Dept. of Pathology and Laboratory Medicine, UC, San Francisco, USA.
| | - Joseph F Urban
- US Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet, Genomic and Immunology Laboratory, Beltsville, MD, USA.
| | - Shawn R Lockery
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR 97403-1254, USA.
| | - John M Hawdon
- Department of Microbiology, Immunology, and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA.
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15
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Morton RA, Baptista-Hon DT, Hales TG, Lovinger DM. Agonist- and antagonist-induced up-regulation of surface 5-HT3 A receptors. Br J Pharmacol 2015; 172:4066-77. [PMID: 25989383 DOI: 10.1111/bph.13197] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 03/25/2015] [Accepted: 05/06/2015] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE The 5-HT3 receptor is a member of the pentameric ligand-gated ion channel family and is pharmacologically targeted to treat irritable bowel syndrome and nausea/emesis. Furthermore, many antidepressants elevate extracellular concentrations of 5-HT. This study investigates the functional consequences of exposure of recombinant 5-HT3 A receptors to agonists and antagonists. EXPERIMENTAL APPROACH We used HEK cells stably expressing recombinant 5-HT3 A receptors and the ND7/23 (mouse neuroblastoma/dorsal root ganglion hybrid) cell line, which expresses endogenous 5-HT3 receptors. Surface expression of recombinant 5-HT3 A receptors, modified to contain the bungarotoxin (BTX) binding sequence, was quantified using fluorescence microscopy to image BTX-conjugated fluorophores. Whole cell voltage-clamp electrophysiology was used to measure the density of current mediated by 5-HT3 A receptors. KEY RESULTS 5-HT3 A receptors were up-regulated by the prolonged presence of agonists (5-HT and m-chlorophenylbiguanide) and antagonists (MDL-72222 and morphine). The up-regulation of 5-HT3 A receptors by 5-HT and MDL-72222 was time- and concentration-dependent but was independent of newly translated receptors. The phenomenon was observed for recombinant rodent and human 5-HT3 A receptors and for endogenous 5-HT3 receptors in neuronal ND7/23 cells. CONCLUSIONS AND IMPLICATIONS Up-regulation of 5-HT3 A receptors, following exposure to either agonists or antagonists suggests that this phenomenon may occur in response to different therapeutic agents. Medications that elevate 5-HT levels, such as the antidepressant inhibitors of 5-HT reuptake and antiemetic inhibitors of 5-HT3 receptor function, may both raise receptor expression. However, this will require further investigation in vivo.
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Affiliation(s)
- Russell A Morton
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, USA.,Department of Pharmacology and Physiology, George Washington University, Washington, DC, USA
| | - Daniel T Baptista-Hon
- Institute of Academic Anaesthesia, Division of Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Tim G Hales
- Department of Pharmacology and Physiology, George Washington University, Washington, DC, USA.,Institute of Academic Anaesthesia, Division of Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, USA.,Department of Pharmacology and Physiology, George Washington University, Washington, DC, USA
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16
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Furlong H, Smith R, Wang J, Seymour C, Mothersill C, Howe O. Identification of Key Proteins in Human Epithelial Cells Responding to Bystander Signals From Irradiated Trout Skin. Dose Response 2015; 13:1559325815597669. [PMID: 26673684 PMCID: PMC4674182 DOI: 10.1177/1559325815597669] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Radiation-induced bystander signaling has been found to occur in live rainbow trout fish (Oncorhynchus mykiss). This article reports identification of key proteomic changes in a bystander reporter cell line (HaCaT) grown in low-dose irradiated tissue-conditioned media (ITCM) from rainbow trout fish. In vitro explant cultures were generated from the skin of fish previously exposed to low doses (0.1 and 0.5 Gy) of X-ray radiation in vivo. The ITCM was harvested from all donor explant cultures and placed on recipient HaCaT cells to observe any change in protein expression caused by the bystander signals. Proteomic methods using 2-dimensional (2D) gel electrophoresis and mass spectroscopy were employed to screen for novel proteins expressed. The proteomic changes measured in HaCaT cells receiving the ITCM revealed that exposure to 0.5 Gy induced an upregulation of annexin A2 and cingulin and a downregulation of Rho-GDI2, F-actin-capping protein subunit beta, microtubule-associated protein RP/EB family member, and 14-3-3 proteins. The 0.1 Gy dose also induced a downregulation of Rho-GDI2, hMMS19, F-actin-capping protein subunit beta, and microtubule-associated protein RP/EB family member proteins. The proteins reported may influence apoptotic signaling, as the results were suggestive of an induction of cell communication, repair mechanisms, and dysregulation of growth signals.
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Affiliation(s)
- Hayley Furlong
- DIT Centre for Radiation and Environmental Science, Focas Research Institute, Dublin Institute of Technology, Dublin, Ireland
- School of Biological Sciences, College of Sciences and Health, Dublin Institute of Technology, Dublin, Ireland
| | - Richard Smith
- Medical Physics and Applied Radiation Sciences, Nuclear Research Building, Hamilton, Canada
| | - Jiaxi Wang
- Queen’s Mass Spectrometry and Proteomics Unit, Department of Chemistry, Queen’s University, Bader Lane, Kingston, Canada
| | - Colin Seymour
- Medical Physics and Applied Radiation Sciences, Nuclear Research Building, Hamilton, Canada
| | - Carmel Mothersill
- Medical Physics and Applied Radiation Sciences, Nuclear Research Building, Hamilton, Canada
| | - Orla Howe
- DIT Centre for Radiation and Environmental Science, Focas Research Institute, Dublin Institute of Technology, Dublin, Ireland
- School of Biological Sciences, College of Sciences and Health, Dublin Institute of Technology, Dublin, Ireland
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17
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Fernandez-Palomo C, Bräuer-Krisch E, Laissue J, Vukmirovic D, Blattmann H, Seymour C, Schültke E, Mothersill C. Use of synchrotron medical microbeam irradiation to investigate radiation-induced bystander and abscopal effects in vivo. Phys Med 2015; 31:584-95. [PMID: 25817634 DOI: 10.1016/j.ejmp.2015.03.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Revised: 03/06/2015] [Accepted: 03/09/2015] [Indexed: 01/01/2023] Open
Abstract
The question of whether bystander and abscopal effects are the same is unclear. Our experimental system enables us to address this question by allowing irradiated organisms to partner with unexposed individuals. Organs from both animals and appropriate sham and scatter dose controls are tested for expression of several endpoints such as calcium flux, role of 5HT, reporter assay cell death and proteomic profile. The results show that membrane related functions of calcium and 5HT are critical for true bystander effect expression. Our original inter-animal experiments used fish species whole body irradiated with low doses of X-rays, which prevented us from addressing the abscopal effect question. Data which are much more relevant in radiotherapy are now available for rats which received high dose local irradiation to the implanted right brain glioma. The data were generated using quasi-parallel microbeams at the biomedical beamline at the European Synchrotron Radiation Facility in Grenoble France. This means we can directly compare abscopal and "true" bystander effects in a rodent tumour model. Analysis of right brain hemisphere, left brain and urinary bladder in the directly irradiated animals and their unirradiated partners strongly suggests that bystander effects (in partner animals) are not the same as abscopal effects (in the irradiated animal). Furthermore, the presence of a tumour in the right brain alters the magnitude of both abscopal and bystander effects in the tissues from the directly irradiated animal and in the unirradiated partners which did not contain tumours, meaning the type of signal was different.
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Affiliation(s)
- Cristian Fernandez-Palomo
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
| | - Elke Bräuer-Krisch
- European Synchrotron Radiation Facility, BP 220 6, rue Jules Horowitz, 38043 Grenoble, France
| | - Jean Laissue
- University of Bern, Hochschulstrasse 4, CH-3012 Bern, Switzerland
| | - Dusan Vukmirovic
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada
| | | | - Colin Seymour
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada
| | - Elisabeth Schültke
- Department of Radiotherapy, Rostock University Medical Center, Südring 75, 18059 Rostock, Germany
| | - Carmel Mothersill
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada
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Szabo A, Kovacs A, Frecska E, Rajnavolgyi E. Psychedelic N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine modulate innate and adaptive inflammatory responses through the sigma-1 receptor of human monocyte-derived dendritic cells. PLoS One 2014; 9:e106533. [PMID: 25171370 PMCID: PMC4149582 DOI: 10.1371/journal.pone.0106533] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 08/08/2014] [Indexed: 12/24/2022] Open
Abstract
The orphan receptor sigma-1 (sigmar-1) is a transmembrane chaperone protein expressed in both the central nervous system and in immune cells. It has been shown to regulate neuronal differentiation and cell survival, and mediates anti-inflammatory responses and immunosuppression in murine in vivo models. Since the details of these findings have not been elucidated so far, we studied the effects of the endogenous sigmar-1 ligands N,N-dimethyltryptamine (NN-DMT), its derivative 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and the synthetic high affinity sigmar-1 agonist PRE-084 hydrochloride on human primary monocyte-derived dendritic cell (moDCs) activation provoked by LPS, polyI:C or pathogen-derived stimuli to induce inflammatory responses. Co-treatment of moDC with these activators and sigma-1 receptor ligands inhibited the production of pro-inflammatory cytokines IL-1β, IL-6, TNFα and the chemokine IL-8, while increased the secretion of the anti-inflammatory cytokine IL-10. The T-cell activating capacity of moDCs was also inhibited, and dimethyltryptamines used in combination with E. coli or influenza virus as stimulators decreased the differentiation of moDC-induced Th1 and Th17 inflammatory effector T-cells in a sigmar-1 specific manner as confirmed by gene silencing. Here we demonstrate for the first time the immunomodulatory potential of NN-DMT and 5-MeO-DMT on human moDC functions via sigmar-1 that could be harnessed for the pharmacological treatment of autoimmune diseases and chronic inflammatory conditions of the CNS or peripheral tissues. Our findings also point out a new biological role for dimethyltryptamines, which may act as systemic endogenous regulators of inflammation and immune homeostasis through the sigma-1 receptor.
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Affiliation(s)
- Attila Szabo
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Research Centre for Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Kovacs
- Department of Psychiatry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Ede Frecska
- Department of Psychiatry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Eva Rajnavolgyi
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Research Centre for Molecular Medicine, University of Debrecen, Debrecen, Hungary
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Seth I, Schwartz JL, Stewart RD, Emery R, Joiner MC, Tucker JD. Neutron exposures in human cells: bystander effect and relative biological effectiveness. PLoS One 2014; 9:e98947. [PMID: 24896095 PMCID: PMC4045982 DOI: 10.1371/journal.pone.0098947] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 05/09/2014] [Indexed: 11/19/2022] Open
Abstract
Bystander effects have been observed repeatedly in mammalian cells following photon and alpha particle irradiation. However, few studies have been performed to investigate bystander effects arising from neutron irradiation. Here we asked whether neutrons also induce a bystander effect in two normal human lymphoblastoid cell lines. These cells were exposed to fast neutrons produced by targeting a near-monoenergetic 50.5 MeV proton beam at a Be target (17 MeV average neutron energy), and irradiated-cell conditioned media (ICCM) was transferred to unirradiated cells. The cytokinesis-block micronucleus assay was used to quantify genetic damage in radiation-naïve cells exposed to ICCM from cultures that received 0 (control), 0.5, 1, 1.5, 2, 3 or 4 Gy neutrons. Cells grown in ICCM from irradiated cells showed no significant increase in the frequencies of micronuclei or nucleoplasmic bridges compared to cells grown in ICCM from sham irradiated cells for either cell line. However, the neutron beam has a photon dose-contamination of 5%, which may modulate a neutron-induced bystander effect. To determine whether these low doses of contaminating photons can induce a bystander effect, cells were irradiated with cobalt-60 at doses equivalent to the percent contamination for each neutron dose. No significant increase in the frequencies of micronuclei or bridges was observed at these doses of photons for either cell line when cultured in ICCM. As expected, high doses of photons induced a clear bystander effect in both cell lines for micronuclei and bridges (p<0.0001). These data indicate that neutrons do not induce a bystander effect in these cells. Finally, neutrons had a relative biological effectiveness of 2.0 ± 0.13 for micronuclei and 5.8 ± 2.9 for bridges compared to cobalt-60. These results may be relevant to radiation therapy with fast neutrons and for regulatory agencies setting standards for neutron radiation protection and safety.
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Affiliation(s)
- Isheeta Seth
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Jeffrey L. Schwartz
- Department of Radiation Oncology, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Robert D. Stewart
- Department of Radiation Oncology, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Robert Emery
- Department of Radiation Oncology, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Michael C. Joiner
- Department of Radiation Oncology, Wayne State University, Detroit, Michigan, United States of America
| | - James D. Tucker
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
- * E-mail:
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Mukherjee D, Coates PJ, Lorimore SA, Wright EG. Responses to ionizing radiation mediated by inflammatory mechanisms. J Pathol 2014; 232:289-99. [PMID: 24254983 DOI: 10.1002/path.4299] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 10/30/2013] [Accepted: 11/05/2013] [Indexed: 01/20/2023]
Abstract
Since the early years of the twentieth century, the biological consequences of exposure to ionizing radiation have been attributed solely to mutational DNA damage or cell death induced in irradiated cells at the time of exposure. However, numerous observations have been at variance with this dogma. In the 1950s, attention was drawn to abscopal effects in areas of the body not directly irradiated. In the 1960s reports began appearing that plasma factors induced by irradiation could affect unirradiated cells, and since 1990 a growing literature has documented an increased rate of DNA damage in the progeny of irradiated cells many cell generations after the initial exposure (radiation-induced genomic instability) and responses in non-irradiated cells neighbouring irradiated cells (radiation-induced bystander effects). All these studies have in common the induction of effects not in directly irradiated cells but in unirradiated cells as a consequence of intercellular signalling. Recently, it has become clear that all the various effects demonstrated in vivo may reflect an ongoing inflammatory response to the initial radiation-induced injury that, in a genotype-dependent manner, has the potential to contribute primary and/or ongoing damage displaced in time and/or space from the initial insult. Importantly, there is direct evidence that non-steroidal anti-inflammatory drug treatment reduces such damage in vivo. These new findings highlight the importance of tissue responses and indicate additional mechanisms of radiation action, including the likelihood that radiation effects are not restricted to the initiation stage of neoplastic diseases, but may also contribute to tumour promotion and progression. The various developments in understanding the responses to radiation exposures have implications not only for radiation pathology but also for therapeutic interventions.
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Affiliation(s)
- Debayan Mukherjee
- Centre for Oncology and Molecular Medicine, University of Dundee Medical School, Dundee, DD1 9SY, UK
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21
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Abstract
The aim of this work was to investigate the impact of intercellular contact during radiation exposure on cell survival in regions of reduced dose. Methods. The PC3 human prostate adenocarcinoma cell line was irradiated using a 6 MV x-ray beam to assess clonogenic cell deaths with the specific aim to investigate cell survival in a dose cold spot. Radiation-induced cell survival in a 20% lower dose region, compared to that of cells receiving 100% of the prescribed dose (2 Gy), was assessed for experimental set-ups when under-irradiated cells were either in direct contact with cells receiving 2 Gy or irradiated separately. In addition, the results were compared against non-irradiated controls. Results. A significant (p < 0.001) decrease in cell survival was found when cells, collocated in the same flask, received either 100% or 80% of the prescribed dose (the dose distribution contained a cold spot of 20% lower dose) compared to non-irradiated cells. However, in the experiment in which the entire flask was exposed to only 80% of the prescribed dose, the mean difference in cell survival compared to non-irradiated control was not significant (p > 0.05). This was contrary to a significant decrease (p < 0.001) in survival of cells receiving 100% of the prescribed dose versus the control. Additionally, significant reduction (p < 0.05) in cell survival was observed for cells which were under-irradiated by 20% but collocated in the same flask with cells receiving 100% dose compared to cells where the entire flask was irradiated with 80% of the prescribed dose. Conclusion. For the given cell line, under existing growing and treatment conditions, the cell survival in the dose cold spot region was significantly lower when under-irradiated cells were in contact with the cells receiving 100% of the prescribed dose compared to survival of cells under-irradiated by the same amount of radiation but treated separately to cells receiving 100% dose.
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Affiliation(s)
- Svetlana Sjostedt
- Medical Physics Department, Radiation Oncology, Royal Adelaide Hospital, South Australian Department of Health , South Australia , Australia
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Cookson EA, Conte IL, Dempster J, Hannah MJ, Carter T. Characterisation of Weibel-Palade body fusion by amperometry in endothelial cells reveals fusion pore dynamics and the effect of cholesterol on exocytosis. J Cell Sci 2013; 126:5490-9. [PMID: 24127569 PMCID: PMC3843139 DOI: 10.1242/jcs.138438] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Regulated secretion from endothelial cells is mediated by Weibel-Palade body (WPB) exocytosis. Plasma membrane cholesterol is implicated in regulating secretory granule exocytosis and fusion pore dynamics; however, its role in modulating WPB exocytosis is not clear. To address this we combined high-resolution electrochemical analysis of WPB fusion pore dynamics, by amperometry, with high-speed optical imaging of WPB exocytosis following cholesterol depletion or supplementation in human umbilical vein endothelial cells. We identified serotonin (5-HT) immunoreactivity in WPBs, and VMAT1 expression allowing detection of secreted 5-HT as discrete current spikes during exocytosis. A high proportion of spikes (∼75%) had pre-spike foot signals, indicating that WPB fusion proceeds via an initial narrow pore. Cholesterol depletion significantly reduced pre-spike foot signal duration and increased the rate of fusion pore expansion, whereas cholesterol supplementation had broadly the reverse effect. Cholesterol depletion slowed the onset of hormone-evoked WPB exocytosis, whereas its supplementation increased the rate of WPB exocytosis and hormone-evoked proregion secretion. Our results provide the first analysis of WPB fusion pore dynamics and highlight an important role for cholesterol in the regulation of WPB exocytosis.
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Affiliation(s)
- Emma A Cookson
- MRC National Institute for Medical Research, Mill Hill, London, NW7 1AA, UK
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Mothersill C, Smith R, Henry M, Seymour C, Wong R. Alternative medicine techniques have non-linear effects on radiation response and can alter the expression of radiation induced bystander effects. Dose Response 2013; 11:82-98. [PMID: 23550268 DOI: 10.2203/dose-response.11-048.mothersill] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Many so-called "alternative medicine" techniques such as Reiki and acupuncture produce very good outcomes for intractable pain and other chronic illnesses but the efficacy is often dismissed as being psychosomatic. However a plausible mechanism does exist i.e. that the treatments alter the electromagnetic fields in living organisms and thereby prevent or reduce activity of neurons which lead to the pain. Low doses of ionising radiation have similar effects on electromagnetic fields and are known to induce signaling cascades in tissues due to ion gradients. To test this hypothesis cell cultures were exposed to Reiki - like and to acupuncture - like treatments, both performed by qualified practitioners. The cells were exposed either before or after the treatment to x-rays and were monitored for production of direct damage or bystander signals. The data suggest that the alternative techniques altered the response of cells to direct irradiation and altered bystander signal mechanisms. We conclude that alternative medicine techniques involving electromagnetic perturbations may modify the response of cells to ionizing radiation. In addition to the obvious implications for mechanistic studies of low dose effects, this could provide a novel target to exploit in radiation protection and in optimizing therapeutic gain during radiotherapy.
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Affiliation(s)
- Carmel Mothersill
- McMaster Institute of Applied Radiation Sciences, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
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Mothersill C, Antonelli F, Dahle J, Dini V, Hegyesi H, Iliakis G, Kämäräinen K, Launonen V, Lumniczky K, Lyng F, Safrany G, Salomaa S, Schilling-Tóth B, Tabocchini A, Kadhim MA. A laboratory inter-comparison of the importance of serum serotonin levels in the measurement of a range of radiation-induced bystander effects: overview of study and results presentation. Int J Radiat Biol 2012; 88:763-9. [PMID: 22891994 DOI: 10.3109/09553002.2012.715795] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Recent research has suggested that serotonin may play an important role in the expression of radiation-induced bystander effects. Serotonin levels in serum were reported to range from 6-22 μM and to correlate inversely with the magnitude of cellular colony-forming ability in medium transfer bystander assays. That is, high serotonin concentration correlated with a low cloning efficiency in cultures receiving medium derived from irradiated cells. METHODS Because of the potential importance of this observation, the European Union's Non-targeted Effects Integrated Project (NOTE) performed an inter-comparison exercise where serum samples with high and low serotonin levels were distributed to seven laboratories which then performed their own assay to determine the magnitude of the bystander effect. RESULTS The results provided some support for a role for serotonin in four of the laboratories. Two saw no difference between the samples and one gave inconclusive results. In this summary paper, full data sets are presented from laboratories whose data was inconclusive or insufficient for a full paper. Other data are published in full in the special issue. CONCLUSION The data suggest that there may be multiple bystander effects and that the underlying mechanisms may be modulated by both the culture conditions and the intrinsic properties of the cells used in the assay.
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Affiliation(s)
- Carmel Mothersill
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada.
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Sjostedt S, Bezak E. Experimental investigation of the cytotoxicity of medium-borne signals in human prostate cancer cell line. Acta Oncol 2012; 51:1086-94. [PMID: 22524215 DOI: 10.3109/0284186x.2012.670264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
INTRODUCTION Evidence exists that exposure of non-irradiated cells to Irradiated Cell Conditioned Medium (ICCM) can cause effects similar to those resulting from direct radiation damage. This study attempts to validate the stochastic model, relating absorbed dose to the emission and processing of cell death signals by non-irradiated cells, in vitro in PC3 human prostate cancer cell line. METHODS The recipient cell survival was measured after exposure of cells to ICMM derived from donor cells: a) exposed to radiation doses from 2 Gy to 8 Gy and b) of concentrations varying from 2 × 10(2) to 6 × 10(6) irradiated with 2 Gy. RESULTS Exposure to ICCM, irradiated with doses between 2-8 Gy, resulted in a significant (p < 0.001) decrease in clonogenic survival of non-irradiated recipient cells compared to the control group. However, dose dependency above 2 Gy was not observed, indicating that any dose threshold was below 2 Gy. A significant (p < 0.001) decrease in survival was found in recipient cells exposed to the ICCM, derived from different concentrations of donor cells exposed to 2 Gy, compared to the control group. The recipient cell survival following exposure to ICCM derived from 2 × 10(2) cells was significantly higher (p < 0.5) compared to the rest of donor cell concentrations, indicating that the toxicity of ICCM depends on the cellular concentration of donor cells. Non-linear regression data fitting provided reasonable agreement with the microdosimetric model for the induction of cell killing through medium-borne signals. CONCLUSION For the given cell line and given experimental conditions, significant decreases in cell survival were observed in non-irradiated cells exposed to ICCM derived from donor cells of various concentrations and irradiated with different doses.
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Affiliation(s)
- Svetlana Sjostedt
- Medical Physics Department, Radiation Oncology, Royal Adelaide Hospital, South Australian Department of Health, South Australia, Australia.
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Fazzari J, Mersov A, Smith R, Seymour C, Mothersill C. Effect of 5-hydroxytryptamine (serotonin) receptor inhibitors on the radiation-induced bystander effect. Int J Radiat Biol 2012; 88:786-90. [DOI: 10.3109/09553002.2012.714519] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Kalanxhi E, Dahle J. The role of serotonin and p53 status in the radiation-induced bystander effect. Int J Radiat Biol 2012; 88:773-6. [DOI: 10.3109/09553002.2012.711919] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Pinho C, Wong R, Sur RK, Hayward JE, Farrell TJ, Seymour C, Mothersill C. The involvement of serum serotonin levels producing radiation-induced bystander effects for an in vivo assay with fractionated high dose-rate (HDR) brachytherapy. Int J Radiat Biol 2012; 88:791-7. [DOI: 10.3109/09553002.2012.715794] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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30
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Chapman KL, Al-Mayah AHJ, Bowler DA, Irons SL, Kadhim MA. No influence of serotonin levels in foetal bovine sera on radiation-induced bystander effects and genomic instability. Int J Radiat Biol 2012; 88:781-5. [DOI: 10.3109/09553002.2012.710926] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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31
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Klammer H, Iliakis G. The impact of serotonin on the development of bystander damage assessed by γ-H2AX foci analysis. Int J Radiat Biol 2012; 88:777-80. [DOI: 10.3109/09553002.2012.703364] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Mothersill C, Smith RW, Fazzari J, McNeill F, Prestwich W, Seymour CB. Evidence for a physical component to the radiation-induced bystander effect? Int J Radiat Biol 2012; 88:583-91. [DOI: 10.3109/09553002.2012.698366] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Kundrát P, Friedland W. Non-linear response of cells to signals leads to revised characteristics of bystander effects inferred from their modelling. Int J Radiat Biol 2012; 88:743-50. [DOI: 10.3109/09553002.2012.698029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Blickwedehl J, Olejniczak S, Cummings R, Sarvaiya N, Mantilla A, Chanan-Khan A, Pandita TK, Schmidt M, Thompson CB, Bangia N. The proteasome activator PA200 regulates tumor cell responsiveness to glutamine and resistance to ionizing radiation. Mol Cancer Res 2012; 10:937-44. [PMID: 22550082 DOI: 10.1158/1541-7786.mcr-11-0493-t] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The cellular response to ionizing radiation (IR) involves a variety of mechanisms to repair damage and maintain cell survival. We previously reported that the proteasome activator PA200 promotes long-term cell survival after IR exposure. The molecular function of PA200 is to enhance proteasome-mediated cleavage after glutamate; however, it is not known how this molecular function promotes survival after IR exposure. Here, we report that upon IR exposure, cellular demand for exogenous glutamine is increased. Cells containing PA200 are capable of surviving this IR-induced glutamine demand, whereas PA200-deficient cells show impaired long-term survival. Additional glutamine supplementation reverses the radiosensitivity of PA200-knockdown cells suggesting impaired glutamine homeostasis in these cells. Indeed, PA200-knockdown cells are unable to maintain intracellular glutamine levels. Furthermore, when extracellular glutamine is limiting, cells that contain PA200 respond by slowing growth, but PA200-knockdown cells and cells in which post-glutamyl proteasome activity is inhibited are nonresponsive and continue rapid growth. This cellular unresponsiveness to nutrient depletion is also reflected at the level of the mTOR substrate ribosomal S6 kinase (S6K). Thus, inability to restrict growth causes PA200-deficient cells to continue growing and eventually die due to lack of available glutamine. Together, these data indicate an important role for PA200 and post-glutamyl proteasome activity in maintaining glutamine homeostasis, which appears to be especially important for long-term survival of tumor cells after radiation exposure.
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LI XUFANG, ZHU GUOYING, WANG JIANPING, WANG YU. Inhibitory effects of autologous γ-irradiated cell conditioned medium on osteoblasts in vitro. Mol Med Rep 2012; 12:273-80. [DOI: 10.3892/mmr.2015.3354] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 01/15/2015] [Indexed: 11/05/2022] Open
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MotherSill C, Seymour C. Changing paradigms in radiobiology. Mutat Res 2012; 750:85-95. [PMID: 22273762 DOI: 10.1016/j.mrrev.2011.12.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 12/20/2011] [Indexed: 12/21/2022]
Abstract
The last 25 years have seen a major shift in emphasis in the field of radiobiology from a DNA-centric view of how radiation damage occurs to a much more biological view that appreciates the importance of macro-and micro-environments, hierarchical organization, underlying genetics, evolution, adaptation and signaling at all levels from atoms to ecosystems. The new view incorporates concepts of hormesis, nonlinear systems, bioenergy field theory, uncertainty and homeodynamics. While the mechanisms underlying these effects and responses are still far from clear, it is very apparent that their implications are much wider than the field of radiobiology. This reflection discusses the changing views and considers how they are influencing thought in environmental and medical science and systems biology.
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Affiliation(s)
- Carmel MotherSill
- McMaster Institute of Applied Radiation Sciences, McMaster University, Hamilton, Ontario, L8S 4K1, Canada.
| | - Colin Seymour
- McMaster Institute of Applied Radiation Sciences, McMaster University, Hamilton, Ontario, L8S 4K1, Canada.
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Balachandran K, Hussain S, Yap CH, Padala M, Chester AH, Yoganathan AP. Elevated cyclic stretch and serotonin result in altered aortic valve remodeling via a mechanosensitive 5-HT(2A) receptor-dependent pathway. Cardiovasc Pathol 2011; 21:206-13. [PMID: 21865058 DOI: 10.1016/j.carpath.2011.07.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 05/29/2011] [Accepted: 07/06/2011] [Indexed: 11/26/2022] Open
Abstract
INTRODUCTION Serotonin/5-hydroxytryptamine (5-HT) has been implicated in valve disease and in the modulation of valve mechanical properties. Several 5-HT receptor subtypes are also known to be mechanosensitive in other cell types, but this has not been studied in the context of the valve. In this study, we sought to understand the effects of elevated 5-HT levels and stretch overload on aortic valve remodeling and the dominant 5-HT receptor subtype that regulates these processes. METHODS AND RESULTS Collagen biosynthesis and tissue mechanical properties of porcine aortic valve cusps were evaluated after 10% (physiologic) and 15% (pathologic) dynamic stretch. These studies were performed in normal medium or medium supplemented with 5-HT (1, 10, 100 μM) in the absence and presence of 5-HT(2A) or 5-HT(2B) receptor antagonists. Fresh valves served as controls. Valve collagen content was maximal at the 10-μM 5-HT concentration for both 10% and 15% stretch. The 5-HT(2A) receptor antagonist reduced collagen synthesis, cell proliferation, and hsp47 expression under elevated and normal stretch, whereas the 5-HT(2B) receptor antagonist was effective only at normal stretch. The pretransition stiffness of the valve cusps was also increased in response to 5-HT via a stretch-sensitive 5-HT(2A) mechanism, with the post-transition stiffness unaltered. CONCLUSIONS Combined elevated stretch and 5-HT resulted in increased valve collagen biosynthesis, cell proliferation, and tissue stiffness. These responses were inhibited by a 5-HT(2A) antagonist. This strongly suggests that the 5-HT(2A) receptor subtype is sensitive to elevated stretch.
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Affiliation(s)
- Kartik Balachandran
- The Wallace H. Coulter School of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0535, USA
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Mothersill C, Bristow RG, Harding SM, Smith RW, Mersov A, Seymour CB. A role for p53 in the response of bystander cells to receipt of medium borne signals from irradiated cells. Int J Radiat Biol 2011; 87:1120-5. [DOI: 10.3109/09553002.2011.610866] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Blyth BJ, Sykes PJ. Radiation-induced bystander effects: what are they, and how relevant are they to human radiation exposures? Radiat Res 2011; 176:139-57. [PMID: 21631286 DOI: 10.1667/rr2548.1] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The term radiation-induced bystander effect is used to describe radiation-induced biological changes that manifest in unirradiated cells remaining within an irradiated cell population. Despite their failure to fit into the framework of classical radiobiology, radiation-induced bystander effects have entered the mainstream and have become established in the radiobiology vocabulary as a bona fide radiation response. However, there is still no consensus on a precise definition of radiation-induced bystander effects, which currently encompasses a number of distinct signal-mediated effects. These effects are classified here into three classes: bystander effects, abscopal effects and cohort effects. In this review, the data have been evaluated to define, where possible, various features specific to radiation-induced bystander effects, including their timing, range, potency and dependence on dose, dose rate, radiation quality and cell type. The weight of evidence supporting these defining features is discussed in the context of bystander experimental systems that closely replicate realistic human exposure scenarios. Whether the manifestation of bystander effects in vivo is intrinsically limited to particular radiation exposure scenarios is considered. The conditions under which radiation-induced bystander effects are induced in vivo will ultimately determine their impact on radiation-induced carcinogenic risk.
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Affiliation(s)
- Benjamin J Blyth
- Haematology and Genetic Pathology, Flinders University, Bedford Park, South Australia 5042, Australia
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Purschke M, Anderson RR, Zurakowski D, Manstein D. Cell-cycle-dependent active thermal bystander effect (ATBE). Lasers Surg Med 2011; 43:230-5. [PMID: 21308697 DOI: 10.1002/lsm.21021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2010] [Indexed: 11/07/2022]
Abstract
OBJECTIVE To determine whether the active thermal bystander effect (ATBE) is cell-cycle dependent. MATERIALS AND METHODS Dividing cells were directly heated for 10 minutes and co-cultured for 24 hours with different bystander cells. We compared the ATBE for dividing and non-dividing human fibroblasts, as well as for dividing human white preadipocytes (HWP) and non-dividing, mature differentiated human white adipocytes. ATBE was assessed as loss of cell viability of the bystander cells by using the MTT assay. Cell-cycle analysis was performed by using flow cytometry. RESULTS Dividing fibroblasts and preadipocytes showed a significant ATBE (P < 0.008 and P < 0.05) with loss of cell viability of about 10% in the temperature range of 40-48°C. There was no significant difference between the extent of the bystander effect for these two cell populations (P = 0.30). In contrast, non-dividing fibroblasts and mature adipocytes did not generate any ATBE within this temperature range. There was a statistically significant difference in ATBE between dividing and non-dividing cell subpopulations for both fibroblasts (P = 0.003) and preadipocytes (P < 0.001) compared to their non-dividing counterparts. CONCLUSION These results suggest that the ATBE is a cell-cycle-dependent process which requires actively dividing cells as receiving bystander cells. The cell-cycle dependency of the ATBE could have useful clinical applications in selectively targeting fast growing cells such as tumor cells. Whether the yield of the ATBE can be amplified by synchronizing the exposure to the ATBE with specific phases of the cell cycle remains subject to further investigation.
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Affiliation(s)
- Martin Purschke
- Massachusetts General Hospital/Harvard Medical School, Wellman Center for Photomedicine, Boston, Massachusetts 02114, USA.
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Sowa MB, Goetz W, Baulch JE, Lewis AJ, Morgan WF. No evidence for a low linear energy transfer adaptive response in irradiated RKO cells. RADIATION PROTECTION DOSIMETRY 2011; 143:311-314. [PMID: 21216730 DOI: 10.1093/rpd/ncq487] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
It has become increasingly evident from reports in the literature that there are many confounding factors capable of modulating radiation-induced non-targeted responses, such as the bystander effect and the adaptive response. In this paper, we examine recent data which suggest that the observation of non-targeted responses may not be universally observable for differing radiation qualities. We have conducted a study of the adaptive response following low-linear energy transfer exposures for human colon carcinoma cells and failed to observe adaption for the endpoints of clonogenic survival or micronucleus formation.
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Affiliation(s)
- M B Sowa
- Cell Biology and Biochemistry, Pacific Northwest National Laboratory, PO BOX 999, MS J4-02, Richland, WA 99354, USA.
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Sokolov MV, Neumann RD. Radiation-induced bystander effects in cultured human stem cells. PLoS One 2010; 5:e14195. [PMID: 21152027 PMCID: PMC2996280 DOI: 10.1371/journal.pone.0014195] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 11/09/2010] [Indexed: 01/06/2023] Open
Abstract
Background The radiation-induced “bystander effect” (RIBE) was shown to occur in a number of experimental systems both in vitro and in vivo as a result of exposure to ionizing radiation (IR). RIBE manifests itself by intercellular communication from irradiated cells to non-irradiated cells which may cause DNA damage and eventual death in these bystander cells. It is known that human stem cells (hSC) are ultimately involved in numerous crucial biological processes such as embryologic development; maintenance of normal homeostasis; aging; and aging-related pathologies such as cancerogenesis and other diseases. However, very little is known about radiation-induced bystander effect in hSC. To mechanistically interrogate RIBE responses and to gain novel insights into RIBE specifically in hSC compartment, both medium transfer and cell co-culture bystander protocols were employed. Methodology/Principal Findings Human bone-marrow mesenchymal stem cells (hMSC) and embryonic stem cells (hESC) were irradiated with doses 0.2 Gy, 2 Gy and 10 Gy of X-rays, allowed to recover either for 1 hr or 24 hr. Then conditioned medium was collected and transferred to non-irradiated hSC for time course studies. In addition, irradiated hMSC were labeled with a vital CMRA dye and co-cultured with non-irradiated bystander hMSC. The medium transfer data showed no evidence for RIBE either in hMSC and hESC by the criteria of induction of DNA damage and for apoptotic cell death compared to non-irradiated cells (p>0.05). A lack of robust RIBE was also demonstrated in hMSC co-cultured with irradiated cells (p>0.05). Conclusions/Significance These data indicate that hSC might not be susceptible to damaging effects of RIBE signaling compared to differentiated adult human somatic cells as shown previously. This finding could have profound implications in a field of radiation biology/oncology, in evaluating radiation risk of IR exposures, and for the safety and efficacy of hSC regenerative-based therapies.
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Affiliation(s)
- Mykyta V Sokolov
- Nuclear Medicine Division, Department of Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, Maryland, United States of America.
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