Abstract | UNLABELLED: METHODS: rECP was radioiodinated with (125)I or (123)I using the Chloramine-T method. The 50% inhibitory concentration value for (125)I-labeled rECP was determined in a competitive cell-binding assay using Beas-2B cells. The binding of radiolabeled rECP to HS side chains was evaluated both in vitro and in vivo. The biodistribution of radiolabeled rECP was assessed in asthma mice or in control mice using SPECT imaging, ex vivo biodistribution measurements, and microautoradiography. RESULTS: The 50% inhibitory concentration value for (125)I-rECP was 7.4 ± 0.1 nM. The loss of HS side chains substantially inhibited the cellular and tissue uptake of (125)I- or (123)I-rECP, indicating that HS side chains of HSPGs are required for (125)I- or (123)I-eosinophil cationic protein binding and uptake both in vitro and in vivo. SPECT imaging demonstrated an appreciably higher accumulation of radioactivity in the lungs of asthma mice than in those of control mice. Ex vivo biodistribution studies also confirmed that there was at least a 4-fold increase in the lung-to-muscle ratio of asthma mice, compared with control mice. The accumulation of radiolabeled rECP was linearly correlated with leukocyte infiltration. CONCLUSION: This study illustrates the feasibility of using radiolabeled rECP for the visualization of HS side chains of HSPGs and the evaluation of allergic lung inflammation in living subjects. Our data indicate that radiolabeled rECP is a novel imaging agent for HS side chains of HSPGs in predicting allergic lung inflammation in living mice.
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Authors | Hui-Chen Chen, Hao-Teng Chang, Po-Han Huang, Margaret Dah-Tsyr Chang, Ren-Shyan Liu, Yu-Jung Lin, Chia-Hung Hsieh |
Journal | Journal of nuclear medicine : official publication, Society of Nuclear Medicine
(J Nucl Med)
Vol. 54
Issue 5
Pg. 793-800
(May 2013)
ISSN: 1535-5667 [Electronic] United States |
PMID | 23520217
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Allergens
- Iodine Radioisotopes
- Recombinant Proteins
- Heparitin Sulfate
- Eosinophil Cationic Protein
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Topics |
- Allergens
(immunology)
- Animals
- Asthma
(complications, diagnostic imaging, immunology)
- Biological Transport
- Cell Line, Tumor
- Disease Models, Animal
- Drug Stability
- Eosinophil Cationic Protein
(metabolism, pharmacokinetics)
- Female
- Gene Expression Regulation
- Heparitin Sulfate
(metabolism)
- Humans
- Hypersensitivity
(complications)
- Inflammation
(diagnostic imaging, immunology)
- Iodine Radioisotopes
- Isotope Labeling
- Leukocytes
(immunology)
- Mice
- Molecular Imaging
(methods)
- Multimodal Imaging
- Positron-Emission Tomography
- Radiochemistry
- Recombinant Proteins
(metabolism, pharmacokinetics)
- Tomography, X-Ray Computed
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