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Alexander TI, Tasma Z, Siow A, Rees TA, Brimble MA, Harris PWR, Hay DL, Walker CS. Novel Fluorescently Labeled PACAP and VIP Highlight Differences between Peptide Internalization and Receptor Pharmacology. ACS Pharmacol Transl Sci 2022; 6:52-64. [PMID: 36654758 PMCID: PMC9841777 DOI: 10.1021/acsptsci.2c00124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Indexed: 12/13/2022]
Abstract
The related peptides pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) have diverse biological functions in peripheral tissues and the central nervous system. Therefore, these peptides and their three receptors represent potential drug targets for several conditions, including neurological and pain-related disorders. However, very little is known about how these peptides regulate their receptors through processes such as internalization. Therefore, we developed tools to study receptor regulation through the synthesis of fluorescently labeled analogues of PACAP-38, PACAP-27, and VIP using copper-mediated 1,3-dipolar cycloaddition of the Cy5 fluorophore. The functionality of Cy5-labeled peptides at their receptors was confirmed in cAMP accumulation assays. Internalization of the Cy5-labeled peptides was then examined and quantified at two distinct PAC1 receptor splice variants, VPAC1 and VPAC2 receptors in transfected cells. All labeled peptides were functional, exhibiting comparable cAMP pharmacology to their unlabeled counterparts and underwent internalization in a time-dependent manner. Temporal differences in the internalization profiles were observed between Cy5-labeled peptides at the PAC1n, PAC1s, VPAC1, and VPAC2 receptors. Interestingly, the pattern of Cy5-labeled peptide activity differed for cAMP accumulation and internalization, indicating that these peptides differentially stimulate cAMP accumulation and internalization and therefore display biased agonism. This novel insight into PACAP-responsive receptor signaling and internalization may provide a unique avenue for future therapeutic development. The fluorescently labeled PACAP and VIP peptides described herein, which we validated as tools to study receptor internalization, will have utility across a broad range of applications and provide greater insight into this receptor family.
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Affiliation(s)
- Tyla I. Alexander
- Department
of Pharmacology and Toxicology, The University
of Otago, Dunedin 9054, New Zealand,Maurice
Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 1010, New Zealand
| | - Zoe Tasma
- Maurice
Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 1010, New Zealand,School
of Biological Sciences, The University of
Auckland, Auckland 1010, New Zealand
| | - Andrew Siow
- School
of Chemical Sciences, The University of
Auckland, Auckland 1010, New Zealand
| | - Tayla A. Rees
- Maurice
Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 1010, New Zealand,School
of Biological Sciences, The University of
Auckland, Auckland 1010, New Zealand
| | - Margaret A. Brimble
- Maurice
Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 1010, New Zealand,School
of Chemical Sciences, The University of
Auckland, Auckland 1010, New Zealand
| | - Paul W. R. Harris
- Maurice
Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 1010, New Zealand,School
of Chemical Sciences, The University of
Auckland, Auckland 1010, New Zealand
| | - Debbie L. Hay
- Department
of Pharmacology and Toxicology, The University
of Otago, Dunedin 9054, New Zealand,Maurice
Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 1010, New Zealand
| | - Christopher S. Walker
- Maurice
Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 1010, New Zealand,School
of Biological Sciences, The University of
Auckland, Auckland 1010, New Zealand,
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Sridharan R, Zuber J, Connelly SM, Mathew E, Dumont ME. Fluorescent approaches for understanding interactions of ligands with G protein coupled receptors. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1838:15-33. [PMID: 24055822 PMCID: PMC3926105 DOI: 10.1016/j.bbamem.2013.09.005] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 09/03/2013] [Accepted: 09/08/2013] [Indexed: 11/18/2022]
Abstract
G protein coupled receptors are responsible for a wide variety of signaling responses in diverse cell types. Despite major advances in the determination of structures of this class of receptors, the underlying mechanisms by which binding of different types of ligands specifically elicits particular signaling responses remain unclear. The use of fluorescence spectroscopy can provide important information about the process of ligand binding and ligand dependent conformational changes in receptors, especially kinetic aspects of these processes that can be difficult to extract from X-ray structures. We present an overview of the extensive array of fluorescent ligands that have been used in studies of G protein coupled receptors and describe spectroscopic approaches for assaying binding and probing the environment of receptor-bound ligands with particular attention to examples involving yeast pheromone receptors. In addition, we discuss the use of fluorescence spectroscopy for detecting and characterizing conformational changes in receptors induced by the binding of ligands. Such studies have provided strong evidence for diversity of receptor conformations elicited by different ligands, consistent with the idea that GPCRs are not simple on and off switches. This diversity of states constitutes an underlying mechanistic basis for biased agonism, the observation that different stimuli can produce different responses from a single receptor. It is likely that continued technical advances will allow fluorescence spectroscopy to play an important role in continued probing of structural transitions in G protein coupled receptors. This article is part of a Special Issue entitled: Structural and biophysical characterisation of membrane protein-ligand binding.
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Affiliation(s)
- Rajashri Sridharan
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Jeffrey Zuber
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Sara M. Connelly
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Elizabeth Mathew
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Mark E. Dumont
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
- Department of Pediatrics, P.O. Box 777, University of Rochester Medical Center, Rochester, NY 14642
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Kosaka N, Ogawa M, Choyke PL, Kobayashi H. Clinical implications of near-infrared fluorescence imaging in cancer. Future Oncol 2009; 5:1501-11. [PMID: 19903075 PMCID: PMC3413951 DOI: 10.2217/fon.09.109] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Near-infrared (NIR) fluorescence cancer imaging is a growing field for both preclinical and clinical application to the clinical management for cancer patients due to its advantageous features, including a high spatial resolution, portability, real-time display and detailed molecular profiling with the multiplexed use of fluorescent probes. In this review, we present a basic concept of NIR fluorescence imaging and overview its potential clinical applications for in vivo cancer imaging, including cancer detection/characterization, lymphatic imaging (sentinel lymph node detection) and surgical/endoscopic guidance. NIR fluorescence imaging can compensate some limitations of conventional imaging modalities, and thus it could play an important role for cancer imaging combined with other modalities in clinical practice.
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Affiliation(s)
- Nobuyuki Kosaka
- Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, MD, USA
| | - Mikako Ogawa
- Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, MD, USA
| | - Peter L Choyke
- Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, MD, USA
| | - Hisataka Kobayashi
- Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Building 10, Room 1B40, MSC1088, Bethesda, MD 20892-1088, USA, Tel.: +1 301 451 4220, Fax: +1 301 402 3191
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Chiou YL, Lin CY. Der p2 activates airway smooth muscle cells in a TLR2/MyD88-dependent manner to induce an inflammatory response. J Cell Physiol 2009; 220:311-8. [PMID: 19326394 DOI: 10.1002/jcp.21764] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Der p2 is a major allergen from Dermatophagoides pteronyssinus, the main species of house dust mite and a major inducer of asthma, inducing harmful respiratory inflammatory responses by activating cells in the respiratory tract, leading to an unstable status. We hypothesize that Der p2 may induce local inflammatory responses by directly affecting airway smooth muscle (ASM) cells. In this study, we demonstrated that Der p2 raised nuclear factor-kappa B (NF-kappaB) and extracellular signal-regulated kinase (ERK) 1/2 activation and induced a high level of proinflammatory cytokines expression in primary cultured ASM cells. Der p2 activated the MyD88 signaling pathway through toll-like receptor (TLR) 2, not through TLR4. Notably, Der p2 stimulated ASM cells to increase phosphorylation of ERK1/2 and expression of c-Fos, which were also important in the T helper type 2 (Th2) immune response. These results suggest that Der p2 induces asthma through the MyD88 signaling pathway in respiratory tissue.
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Affiliation(s)
- Ya-Ling Chiou
- Institute of Immunology & Microbiology, National Yang-Ming University, Taipei, Taiwan, ROC
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Targeting gelatinases with a near-infrared fluorescent cyclic His-Try-Gly-Phe peptide. Mol Imaging Biol 2009; 11:424-33. [PMID: 19424760 DOI: 10.1007/s11307-009-0219-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 12/18/2008] [Accepted: 01/16/2009] [Indexed: 10/20/2022]
Abstract
PURPOSE The purpose of the study is to synthesize and characterize near-infrared (NIR) fluorescence imaging probes targeted to gelatinases. PROCEDURES A phage display-selected cyclic peptide containing the His-Try-Gly-Phe (HWGF) motif was used as the lead compound. Structure-activity relationship analysis was used to identify stable and potent gelatinase inhibitors suitable for NIR imaging applications. RESULTS Replacing the S-S bond in cyclic peptide c(CTTHWGFTLC)NH(2) (C1) with an amide bond between the epsilon-amino group of Lys and the side chain of Asp resulted in a significant increase in stability and a fourfold increase in gelatinase inhibition of the resulting peptide, c(KAHWGFTLD)NH(2) (C6). Conjugation of Cy5.5 to C6 led to Cy5.5-C6, which was selectively taken up by MMP-2 expressing human glioma U87 cells. In vivo, selective accumulation of Cy5.5-C6, but not Cy5.5-C1 or a Cy5.5-scrambled peptide conjugate, was visualized in intratibial prostate PC-3 tumors 48 h after their intravenous injection. Moreover, Cy5.5-C6 was readily visualized in orthotopically inoculated U87 brain tumors. CONCLUSIONS Cy5.5-C6 may be a useful agent for molecular imaging of gelatinases. The approach of producing stable cyclic peptides through side chain amide linkage should be applicable to other peptide-based imaging agents.
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Sutton EJ, Henning TD, Pichler BJ, Bremer C, Daldrup-Link HE. Cell tracking with optical imaging. Eur Radiol 2008; 18:2021-32. [PMID: 18506449 DOI: 10.1007/s00330-008-0984-z] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2006] [Revised: 12/18/2007] [Accepted: 01/17/2008] [Indexed: 12/22/2022]
Abstract
Adaptability, sensitivity, resolution and non-invasiveness are the attributes that have contributed to the longstanding use of light as an investigational tool and form the basis of optical imaging (OI). OI, which encompasses numerous techniques and methods, is rapid (<5 min), inexpensive, noninvasive, nontoxic (no radiation) and has molecular (single-cell) sensitivity, which is equal to that of conventional nuclear imaging and several orders of magnitude greater than MRI. This article provides a comprehensive overview of emerging applications of OI-based techniques for in vivo monitoring of new stem cell-based therapies. Different fluorochromes for cell labeling, labeling methods and OI-based cell-tracking techniques will be reviewed with respect to their technical principles, current applications and aims for clinical translation. Advantages and limitations of these new OI-based cell-tracking techniques will be discussed. Non-invasive mapping of cells labeled with fluorochromes or OI marker genes has the potential to evolve further within the clinical realm.
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Affiliation(s)
- Elizabeth J Sutton
- Department of Radiology, University of California, San Francisco, CA 94143-0628, USA
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Yang Z, Zheng S, Harrison WJ, Harder J, Wen X, Gelovani JG, Qiao A, Li C. Long-circulating near-infrared fluorescence core-cross-linked polymeric micelles: synthesis, characterization, and dual nuclear/optical imaging. Biomacromolecules 2007; 8:3422-8. [PMID: 17958440 DOI: 10.1021/bm7005399] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the synthesis of PEG-coated, core-cross-linked polymeric micelles (CCPMs) derived from an amine-terminated amphiphilic block copolymer, poly(PEG-methacrylate)-b-poly(triethoxysilyl propylmethacrylate). The block copolymer self-assembled to form micellar nanoparticles, and a Cy-7-like near-infrared fluorescence (NIRF) dye was entrapped in the core bearing reactive ethoxysilane functional groups through a subsequent sol-gel process. The fluorescent signal of CCPMs on the molar basis was 16-fold brighter than that of Cy7. With an average diameter of 24 +/- 8.9 nm, CCPMs exhibited a prolonged blood half-life (t1/2,alpha = 1.25 h; t1/2,beta = 46.18 h) and moderate uptake by the mononuclear phagocytic system. Significant accumulation of CCPMs in human breast tumor xenografts allowed noninvasive monitoring of the uptake kinetics with both NIRF optical and gamma imaging techniques. Our data suggest that Cy7-entrapped CCPM nanoparticles are suitable for NIRF imaging of solid tumors and have potential applications in the imaging of tumor-associated molecular markers.
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Affiliation(s)
- Zhi Yang
- Department of Experimental Diagnostic Imaging, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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Gunn AJ, Brechbiel MW, Choyke PL. The emerging role of molecular imaging and targeted therapeutics in peritoneal carcinomatosis. Expert Opin Drug Deliv 2007; 4:389-402. [PMID: 17683252 DOI: 10.1517/17425247.4.4.389] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Peritoneal carcinomatosis is a common and often fatal late-stage complication of many gastrointestinal and gynecologic malignancies. This review discusses the ongoing evolution of diagnostic and treatment strategies for peritoneal carcinomatosis and the role that molecular imaging and radioimmunotherapy may play in improving patient survival. An overview of recent developments in targeted imaging and therapeutics for peritoneal carcinomatosis, as well as the authors' opinions as to future developments in this field is also provided.
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Affiliation(s)
- Andrew J Gunn
- Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815-6789, USA
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Berger C, Gremlich HU, Schmidt P, Cannet C, Kneuer R, Hiestand P, Rausch M, Rudin M. In vivo monitoring the fate of Cy5.5-Tat labeled T lymphocytes by quantitative near-infrared fluorescence imaging during acute brain inflammation in a rat model of experimental autoimmune encephalomyelitis. J Immunol Methods 2007; 323:65-77. [PMID: 17433359 DOI: 10.1016/j.jim.2007.02.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 02/09/2007] [Accepted: 02/21/2007] [Indexed: 11/28/2022]
Abstract
T cells and macrophages directed against myelin proteins orchestrate the inflammation process in multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). So far, assessment of macrophages infiltration or structural alterations has been achieved by in vivo imaging. In this work, we show the infiltration of Cy5.5-labeled T lymphocytes into the brains of EAE rats by reflectance near-infrared fluorescence imaging. T lymphocytes were labeled with Cy5.5-Tat and administered intravenously to naïve or EAE animals. The highest fluorescence signal was observed for EAE animals, which received myelin-activated T cells during the acute phase of the disease. The temporal profile of fluorescence in this group paralleled the pattern of neurological impairment during the acute phase, the remittance and first relapses of EAE. No disease specific fluorescence pattern was observed for EAE animals, which received naïve T cells. However, uptake of Cy5.5-Tat by scavenger cells (e.g. macrophages) following death of labeled T cells in vivo prevents prolonged longitudinal studies. Our work demonstrates that Cy5.5-Tat labeling of T cells is suitable for in vivo fluorescence imaging of inflammation initiation in the EAE model. This approach may particularly be useful for evaluation of novel anti-inflammatory therapies.
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Affiliation(s)
- Cedric Berger
- Novartis Institutes for Biomedical Research, Basel, Switzerland
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Abstract
Recently, many novel peptide-based near-infrared (NIR) fluorescent molecular probes have been developed for in vivo biomedical imaging. To report specific information of biological targets, the probes were individually designed according to the unique property or functions of their targets. These peptide-based probes can be classified into targeting, crosslinking, and enzyme-activatable probes. Several of them have been tested in various in vitro and in vivo models, and the obtained imaging information has been applied to disease detection, medical diagnosis, and drug evaluations.
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Affiliation(s)
- Ching-Hsuan Tung
- Center for Molecular Imaging Research, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA.
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Abstract
With an increasing understanding of the molecular basis of disease, various new imaging targets have recently been defined that potentially allow for an early, sensitive, and specific diagnosis of disease or monitoring of treatment response. Different approaches to depict these molecular structures in vivo are currently being explored by the molecular imaging community. We briefly review methodologies for molecular imaging by magnetic resonance imaging and optical methods. Special emphasis is put on different contrast agent designs (e.g., targeted and smart probes). New technical developments in optical imaging are briefly discussed. In addition, current research results are put into a clinical perspective to elucidate the potential merits one might expect from this new research field.
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Affiliation(s)
- T Persigehl
- Department of Clinical Radiology, University Hospital Muenster, Albert-Schweitzer-Str. 33, D-48129 Münster, Germany
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Wang W, Ke S, Wu Q, Charnsangavej C, Gurfinkel M, Gelovani JG, Abbruzzese JL, Sevick-Muraca EM, Li C. Near-Infrared Optical Imaging of Integrin αvβ3in Human Tumor Xenografts. Mol Imaging 2004; 3:343-51. [PMID: 15802051 DOI: 10.1162/15353500200404148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
In vivo optical imaging is potentially useful for evaluating the presence of tumor markers that are targets of molecular medicine. Here we report the synthesis and characterization of integrin alphavbeta3-targeted peptide cyclo(Lys-Arg-Gly-Asp-Phe) [c(KRGDf )] labeled with fluorescence dyes with wavelength spanning from the visible/near infrared (Cy5.5) to the true near infrared (IRDye800) for optical imaging. In vitro, the peptide-dye conjugates bound specifically to tumor cells expressing alphavbeta3. When administered intravenously into mice at a dose of 6 nmol /mouse, the conjugates accumulated in tumors expressing alphavbeta3. The tumor-to-background ratios for human KS1767 Kaposi's sarcoma in mice injected with Cy5.5-c(KRGDf ) and Cy5.5 were 5.5 and 1.5, respectively. Preinjection of c(KRGDf ) blocked the uptake of Cy5.5-c(KRGDf ) in tumors by 89%. In alphavbeta3-positive M21 and alphavbeta3-negative M21-L human melanoma, fluorescence intensity in the tumor of mice injected with IRDye800 - c(KRGDf ) was 2.3 and 1.3 times that in normal tissue, respectively. Dynamic imaging revealed that Cy5.5- c(KRGDf ) was rapidly taken up by KS1767 tumor immediately after bolus injection. The rate of its uptake in the tumor was reduced by preinjection of c(KRGDf ) in an interval time-dependent manner. Our data suggest that near-infrared fluorescence imaging may be applied to the detection of tumors expressing integrin alphavbeta3 and to the assessment of the optimal biological dose and schedule of targeted therapies.
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Affiliation(s)
- Wei Wang
- Department of Experimental Diagnostic Imaging, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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Hansch A, Frey O, Hilger I, Sauner D, Haas M, Schmidt D, Kurrat C, Gajda M, Malich A, Bräuer R, Kaiser WA. Diagnosis of Arthritis Using Near-Infrared Fluorochrome Cy5.5. Invest Radiol 2004; 39:626-32. [PMID: 15377942 DOI: 10.1097/01.rli.0000139008.04288.fd] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
PURPOSE Near-infrared range fluorescence (NIRF) imaging is a potential tool to diagnose biologic processes in vivo. This applicability study sought to define whether imaging with fluorochrome Cy5.5 can identify arthritis in murine antigen-induced arthritis (AIA). MATERIALS AND METHODS On day 7 of AIA (n = 9 mice), fluorescence intensities in inflamed and contralateral knee joints (the latter as internal control) were measured before and after intravenous injection of Cy5.5 (until 72 hours). Cy5.5 joint deposition was verified by confocal laser-scanning microscopy. Dye phagocytosis was evaluated in cultured macrophages (cell line PMJ2-R) by FACS analysis. Cy5.5 binding to serum protein was tested by NIRF scanning and gel electrophoresis. RESULTS Between 2 and 72 hours, the arthritic knee joints showed significantly higher fluorescence intensities compared with contralateral joints. Microscopy confirmed Cy5.5 deposition in the synovial membrane. Cultured macrophages actively phagocytosed Cy5.5. Cy5.5 bound mainly to albumin as the main serum protein. CONCLUSION NIRF imaging with Cy5.5 can identify arthritic joints in vivo, likely due to nonspecific deposition.
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Affiliation(s)
- Andreas Hansch
- Institute of Diagnostic and Interventional Radiology, Friedrich Schiller University Jena, Jena, Germany.
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Grötzinger C, Wiedenmann B. Somatostatin receptor targeting for tumor imaging and therapy. Ann N Y Acad Sci 2004; 1014:258-64. [PMID: 15153442 DOI: 10.1196/annals.1294.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Somatostatin receptors and their ligands constitute the prototype targeting system for contrast-enhanced detection and radiotherapy of cancer. Radiolabeled synthetic analogs of somatostatin have been successfully used in routine molecular imaging of primary gastroenteropancreatic neuroendocrine tumors and their metastases for more than 15 years. Likewise, analog conjugates for radiation therapy have been developed and have been under clinical trial for several years. The vast amount of knowledge accumulated by both basic and clinical science has made the somatostatin/somatostatin receptor system a popular model for new targeting strategies in imaging and therapy. Among those, the use of near-infrared fluorescent dye-peptide conjugates for the detection of tumors by endoscopy, mammography, or intraoperative imaging is one of the most promising. This article reviews recent developments in the field and discusses concepts for receptor-targeted molecular imaging and therapy.
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Affiliation(s)
- Carsten Grötzinger
- Charité Medical School, Campus Virchow Hospital, Department of Internal Medicine, Division of Hepatology and Gastroenterology, 13353 Berlin, Germany
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Wunderbaldinger P, Turetschek K, Bremer C. Near-infrared fluorescence imaging of lymph nodes using a new enzyme sensing activatable macromolecular optical probe. Eur Radiol 2003; 13:2206-11. [PMID: 12802615 DOI: 10.1007/s00330-003-1932-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2003] [Revised: 03/17/2003] [Accepted: 04/01/2003] [Indexed: 11/29/2022]
Abstract
The aim of this study was to validate the use of near infrared fluorescence imaging (NIRF) using enzyme-sensitive optical probes for lymph node detection. An optical contrast probe that is activated by cystein proteases, such as cathepsin B, was used to visualize lymph nodes by NIRF reflectance imaging. In order to quantitate the uptake of the optical probe in lymphatic tissue, the biodistribution was assessed using the Indium-111 labeled optical probe. Sixteen Balb-c mice were injected either intravenously (i.v.) or subcutaneously (s.c.) with the NIRF-probe (2 micromol cyanine (Cy)/animal; i.v., n=10; s.c., n=6) and imaged 24 h after injection. Signal intensities and target-to-background ratios of various lymph nodes were measured by manual regions of interest (ROIs). Additional signal intensity measurements were performed of excised lymph nodes (n=21) from i.v. injected mice (24 h after injection) and compared with excised lymph nodes (n=8) of non-injected mice. The probe employed in this study was lymphotropic with approximately 3-4% accumulation in lymph nodes (3.4+/-0.8% ID/g). Measurements of the excised lymph nodes (after i.v. injection) confirmed a significant increase in lymph node fluorescence signal from baseline 26+/-7.6 arbitary units (AU) to 146+/-10.9 AU (p<0.0001). A significant increase in lymph node fluorescence signal was also seen in vivo throughout the body after i.v. injection (96+/-7.8 AU) and/or regionally after s.c. injection (141+/-11.5 AU) in comparison with baseline autofluorescence (26+/-7.6 AU). Target-to-background ratio was significantly higher after s.c. injection (6.6%+/-0.81) compared with i.v. injection (4.8+/-0.67%). Detection and visualization of lymph nodes is feasible by NIRF imaging using a cystein-protease sensitive optical probe.
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Affiliation(s)
- Patrick Wunderbaldinger
- Department of Radiology, University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria.
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The Biological Significance of PACAP and PACAP Receptors in Human Tumors: From Cell Lines to Cancers. PITUITARY ADENYLATE CYCLASE-ACTIVATING POLYPEPTIDE 2003. [DOI: 10.1007/978-1-4615-0243-2_17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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