"Synthesis, Labeling, and Stability of ECL1i. The ECL1i peptide (LGTFLKC) was synthesized from d-form amino acids by CPC Scientific (Sunnyvale, Calif)."
Abstract
A chemokine receptor type 2–binding peptide adapted as a PET probe can help detect lung inflammation in a mouse model and human tissues.
Purpose
To characterize a chemokine receptor type 2 (CCR2)–binding peptide adapted for use as a positron emission tomography (PET) radiotracer for noninvasive detection of lung inflammation in a mouse model of lung injury and in human tissues from subjects with lung disease.
Materials and Methods
The study was approved by institutional animal and human studies committees. Informed consent was obtained from patients. A 7-amino acid CCR2 binding peptide (extracellular loop 1 inverso [ECL1i]) was conjugated to tetraazacyclododecane tetraacetic acid (DOTA) and labeled with copper 64 (64Cu) or fluorescent dye. Lung inflammation was induced with intratracheal administration of lipopolysaccharide (LPS) in wild-type (n = 19) and CCR2-deficient (n = 4) mice, and these mice were compared with wild-type mice given control saline (n = 5) by using PET performed after intravenous injection of 64Cu-DOTA-ECL1i. Lung immune cells and those binding fluorescently labeled ECL1i in vivo were detected with flow cytometry. Lung inflammation in tissue from subjects with nondiseased lungs donated for lung transplantation (n = 11) and those with chronic obstructive pulmonary disease (COPD) who were undergoing lung transplantation (n = 16) was evaluated for CCR2 with immunostaining and autoradiography (n = 6, COPD) with 64Cu-DOTA-ECL1i. Groups were compared with analysis of variance, the Mann-Whitney U test, or the t test.
Results
Signal on PET images obtained in mouse lungs after injury with LPS was significantly greater than that in the saline control group (mean = 4.43% of injected dose [ID] per gram of tissue vs 0.99% of injected dose per gram of tissue; P < .001). PET signal was significantly diminished with blocking studies using nonradiolabeled ECL1i in excess (mean = 0.63% ID per gram of tissue; P < .001) and in CCR2-deficient mice (mean = 0.39% ID per gram of tissue; P < .001). The ECL1i signal was associated with an elevated level of mouse lung monocytes. COPD lung tissue displayed significantly elevated CCR2 levels compared with nondiseased tissue (median = 12.8% vs 1.2% cells per sample; P = .002), which was detected with 64Cu-DOTA-ECL1i by using autoradiography.
Conclusion
64Cu-DOTA-ECL1i is a promising tool for PET-based detection of CCR2-directed inflammation in an animal model and in human tissues as a step toward clinical translation.
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CPC Scientific Inc., a leading global peptide CRDMO (Contract Research, Development, and Manufacturing Organization) has invested in a new peptide API (Active Pharmaceutical Ingredient) manufacturing site, bringing many new jobs to Rocklin, California. The 41,000 sq ft facility located at 3880 Atherton Rd, Rocklin, CA 95765 will be utilized to manufacture clinical to commercial grade peptide products for increased manufacturing capacity and will diversify CPC Scientific’s supply chain.
CPC Scientific is entering an exciting period of growth and innovation for peptide and oligonucleotide therapeutic development and manufacturing, and we will continue to provide therapeutic APIs to pharmaceutical and biotech companies around the world. We are very pleased to partner with the City of Rocklin, California to bring manufacturing and Life-Science jobs to local American workers,” said Shawn Lee, PhD, CEO.
Ikeda, Z., Kakegawa, K., Kikuchi, F., Itono, S., Oki, H., Yashiro, H., Hiyoshi, H., Tsuchimori, K., Hamagami, K., Watanabe, M. and Sasaki, M. Journal of Medicinal Chemistry 65, no. 12 (2022): 8456-8477.
- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraokahigashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
Subsequently, 5FAM–Abu–Gly–Asp–Asp–Asp–Lys–Ile–Val–Gly–Gly–Lys(CPQ2)–Lys–Lys–NH2 (purity: 97.2%, CPC Scientific, Inc.) was diluted with an assay buffer to prepare a 2.1 μM substrate solution.
The transferred energy from a fluorescent donor is converted into molecular vibrations if the acceptor is a non-fluorescent dye (quencher). When the FRET is terminated (by separating donor and acceptor), an increase of donor fluorescence can be detected. The design and synthesis work at CPC for FRET and TR-FRET peptide substrates include modification of sequences, selection of donor/quencher pairs, improvement of FRET substrate solubility and quenching efficiency.
Genomics research shows that more than a million proteins are encoded by approximately 30,000 human genes. Proteomics, the study of proteins encoded by the genome, includes identifying post-translational modifications, structural analyses, protein localization studies, and protein quantitation. Mass spectroscopybased techniques have evolved as a powerful tool in proteomics. Stable isotope-labeled peptides (SIL peptides) are chemically and physically indistinguishable from their endogenous counterparts concerning retention time, ionization efficiency, and fragmentation pathways.
Peptides play a vital role in the pharmaceutical industry and drug therapeutic development; however, their in vivo applications are sometimes limited due to fast degradation by proteases, poor solubility, antigenic responses, and glomerular filtration in the kidney. The covalent attachment of polyethylene glycol (PEG) chains to peptides is one approach that can reduce immunogenicity, improve solubility, and reduce renal clearance.
Hydrocarbon-stapled peptides are locked into their bioactive alpha-helical conformation through the site-specific introduction of a chemical brace, an all-hydrocarbon staple. The idea of peptide stapling was introduced to overcome the limitations of two broad classes of therapeutic agents (small molecules and protein biologics) in targeting intracellular protein-protein interactions. Small molecules only work on proteins with a specific surface feature, and most protein biologics do not penetrate cells. Because stapled peptides are locked into a stabilized α-helical structure (the most common element of protein secondary structures), they can easily penetrate cells.
![Locmi-AKH-I, cycloAKH (cyclo[LNFTPNWG]](https://test.cpcscientific.com/wp-content/uploads/2022/05/cyclo-LNFTPNWG-v2-1500sm.png)
Mogford, Jon E., George E. Davis, Steven H. Platts, and Gerald A. Meininger. Circulation research 79, no. 4 (1996): 821-826.
Locmi-AKH-I, cycloAKH (cyclo[LNFTPNWG]
CPC Scientific is pleased to announce and welcome David A. Godkin as VP of Business Operations! David will be responsible for the growth and development of our HR department and facilities management division. He brings 20+ years of experience in human resources and facility operations from the peptide industry. We are confident David will have […]
Bekdemir, Ahmet, Eden EL Tanner, Jesse Kirkpatrick, Ava P. Soleimany, Samir Mitragotri, and Sangeeta N. Bhatia Advanced Healthcare Materials (2022): 2102685.
Peptides [TDN-qFAM, C-(PEG)2-K(CPQ2)-GGGSRPfGG-5FAM] were obtained from Tufts University Peptide Core Facility or CPC Scientific, Inc (USA)
