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Karachaliou CE, Triantis C, Liolios C, Palamaris L, Zikos C, Tsitsilonis OE, Kalbacher H, Voelter W, Loudos G, Papadopoulos M, Pirmettis I, Livaniou E. In vivo biodistribution and imaging studies with a 99mTc-radiolabeled derivative of the C-terminus of prothymosin alpha in mice bearing experimentally-induced inflammation. Eur J Pharm Biopharm 2017; 113:188-197. [PMID: 28087377 DOI: 10.1016/j.ejpb.2016.12.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/15/2016] [Accepted: 12/14/2016] [Indexed: 10/20/2022]
Abstract
Prothymosin alpha (ProTα) is a highly conserved mammalian polypeptide (109 amino acids in man) exerting in vitro and in vivo immunoenhancing activities. Recently, our team has developed a 99mTc-radiolabeled derivative of the C-terminal bioactive decapeptide of ProTα ([99mTc]C1) and employed it in in vitro studies, the results of which support the existence of binding sites on human neutrophils that recognize [99mTc]C1, intact ProTα as well as the C-terminal decapeptide of ProTα and presumably involve Toll-like receptor 4. In the present work, [99mTc]C1 was administered to Swiss albino mice with experimentally-induced inflammation for in vivo biodistribution and imaging studies, in parallel with a suitable negative control, which differs from [99mTc]C1 only in bearing a scrambled version of the ProTα decapeptide. The biodistribution data obtained with [99mTc]C1 demonstrated fast clearance of radioactivity from blood, heart, lungs, normal muscle, and predominantly urinary excretion. Most importantly, slow clearance of radioactivity from the inflammation focus was observed, resulting in a high ratio of inflamed/normal muscle tissue (9.15 at 30min post injection, which remained practically stable up to 2h). The inflammation-targeting capacity of [99mTc]C1 was confirmed by imaging studies and might be attributed to neutrophils, which are recruited at the inflamed areas and bear binding sites for [99mTc]C1. In this respect, apart from being a valuable tool for further studies on ProTα in in vitro and in vivo systems, [99mTc]C1 merits further evaluation as a radiopharmaceutical for specific imaging of inflammation foci.
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Affiliation(s)
- Chrysoula-Evangelia Karachaliou
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Charalampos Triantis
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Christos Liolios
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Lazaros Palamaris
- Department of Medical Instruments Technology, Technological Educational Institute, Athens 12243, Greece
| | - Christos Zikos
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Ourania E Tsitsilonis
- Division of Animal and Human Physiology, Department of Biology, University of Athens, Athens 15784, Greece
| | - Hubert Kalbacher
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen 72076, Germany
| | - Wolfgang Voelter
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen 72076, Germany
| | - George Loudos
- Department of Medical Instruments Technology, Technological Educational Institute, Athens 12243, Greece
| | - Minas Papadopoulos
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Ioannis Pirmettis
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Evangelia Livaniou
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece.
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Karachaliou CE, Liolios C, Triantis C, Zikos C, Samara P, Tsitsilonis OE, Kalbacher H, Voelter W, Papadopoulos M, Pirmettis I, Livaniou E. Specific in vitro binding of a new (99m)Tc-radiolabeled derivative of the C-terminal decapeptide of prothymosin alpha on human neutrophils. Int J Pharm 2015; 486:1-12. [PMID: 25796124 DOI: 10.1016/j.ijpharm.2015.03.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/13/2015] [Accepted: 03/16/2015] [Indexed: 11/28/2022]
Abstract
Prothymosin alpha (ProTα) is a conserved mammalian polypeptide with intracellular functions associated with cell proliferation and apoptosis and an extracellular role associated with immunopotentiation. The N-terminal fragment [1-28], which is identical with the immunostimulating peptide thymosin α1 (Tα1), was earlier considered as the immunoactive region of the polypeptide; however, recent data suggest that ProTα may exert a discrete immunomodulating action through its central or C-terminal region, via targeting Toll-like receptor- 4 (TLR4). In this work, a derivative of the C-terminal fragment ProTα[100-109] (ProTα-D1) that can be radiolabeled with (99m)Tc was developed. The biological activity of the non-radioactive (185/187)rhenium-complex of this derivative ([(185/187)Re]ProTα-D1, structurally similar with [(99m)Tc]ProTα-D1) was verified through suitable in vitro bioassays on human neutrophils. Subsequent cell-binding studies revealed specific, time-dependent and saturable binding of [(99m)Tc]ProTα-D1 on neutrophils, which was inhibited by intact ProTα and ProTα[100-109], as well as by a "prototype" TLR4-ligand (lipopolysaccharide from Escherichia coli). Overall, our results support the existence of ProTα-binding sites on human neutrophils, recognizing [(99m)Tc]ProTα-D1, which might involve TLR4. [(99m)Tc]ProTα-D1 may be a useful tool for conducting further in vitro and in vivo studies, aiming to elucidate the extracellular mode of action of ProTα and, eventually, develop ProTα-based immunotherapeutics.
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Affiliation(s)
- Chrysoula-Evangelia Karachaliou
- Institute of Nuclear and Radiological Sciences & Technology, Energy and Safety (INRaSTES), National Center for Scientific Research "Demokritos", Athens 15310, Greece
| | - Christos Liolios
- Institute of Nuclear and Radiological Sciences & Technology, Energy and Safety (INRaSTES), National Center for Scientific Research "Demokritos", Athens 15310, Greece
| | - Charalampos Triantis
- Institute of Nuclear and Radiological Sciences & Technology, Energy and Safety (INRaSTES), National Center for Scientific Research "Demokritos", Athens 15310, Greece
| | - Christos Zikos
- Institute of Nuclear and Radiological Sciences & Technology, Energy and Safety (INRaSTES), National Center for Scientific Research "Demokritos", Athens 15310, Greece
| | - Pinelopi Samara
- Faculty of Biology, University of Athens, Athens 15784, Greece
| | | | - Hubert Kalbacher
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen 72076, Germany
| | - Wolfgang Voelter
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen 72076, Germany
| | - Minas Papadopoulos
- Institute of Nuclear and Radiological Sciences & Technology, Energy and Safety (INRaSTES), National Center for Scientific Research "Demokritos", Athens 15310, Greece
| | - Ioannis Pirmettis
- Institute of Nuclear and Radiological Sciences & Technology, Energy and Safety (INRaSTES), National Center for Scientific Research "Demokritos", Athens 15310, Greece
| | - Evangelia Livaniou
- Institute of Nuclear and Radiological Sciences & Technology, Energy and Safety (INRaSTES), National Center for Scientific Research "Demokritos", Athens 15310, Greece.
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New labeled derivatives of the neuroprotective peptide colivelin: Synthesis, characterization, and first in vitro and in vivo applications. Arch Biochem Biophys 2015; 567:83-93. [DOI: 10.1016/j.abb.2014.12.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/15/2014] [Accepted: 12/29/2014] [Indexed: 12/25/2022]
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