"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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Shurtleff, V.W., Layton, M.E., Parish, C.A., Perkins, J.J., Schreier, J.D., Wang, Y., Adam, G.C., Alvarez, N., Bahmanjah, S., Bahnck-Teets, C.M. and Boyce, C.W. Journal of Medicinal Chemistry 67, no. 5 (2024): 3935-3958.
- Center for Discovery and Innovation, Hackensack Meridian Health. 111 Ideation Way. Nutley, New Jersey 07110, United States.
- Merck & Co., Inc., Rahway, New Jersey 07065, United States.
The enzymatic activity of recombinantly expressed 3CLPro enzymes from different coronaviruses was measured using the following synthetic quenched FRET peptide: CP488-ESATLQSGLRKAK- (CPQ2)-NH2 (CPC Scientific, San Jose, CA.
Goh, Joleen Pei Zhen. Nanyang Technological University (2023)
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- Merck & Co., Inc., Kenilworth, NJ 07033, USA.
- Merck & Co., Inc., Boston, MA 02115, USA
- Merck & Co., Inc., West Point, PA 19486, USA
- Genentech, South San Francisco, CA 94080, USA
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All peptides and oligonucleotides were synthesized and HPLC purified by CPC Scientific and Integrated DNA Technologies (IDT), respectively. Peptide–oligonucleotide conjugates were generated by copper-free click chemistry.
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- Research, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
- Pharmaceutical Sciences, Takeda Pharmaceutical Company Ltd., 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
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Senotherapeutic peptide treatment reduces biological age and senescence burden in human skin models.
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The top hit peptides selected (Pep 14, 144, 156, 195, and 393) from the screening and the fluorescence labeled peptide (5FAM-PEG2-Pep 14) were purchased from CPC Scientific Inc. (USA), which synthesized the peptide by solid phase (Fmoc) on a Rink amide resin, with >95% purity, in the form of acetate salt.
Synthetic oligonucleotides constitute an important class of therapeutics developed to treat a variety of indications. Two main synthetic approaches exist for the conjugation of a peptide to an oligonucleotide: parallel and linear. The primary benefit of the linear approach is the one-pot solid-phase assembly and compatibility with machine automation. However, in cases where poor compatibility of peptide and oligo chemistries exist or long peptide and oligo fragments are required, preparing both components separately and linking both compounds together may offer the simplest solution.
Solid-phase peptide synthesis (SPPS) approaches require that the side chains of certain amino acids be protected from undesired reactivity during synthesis. The installation and removal of these protection groups results in a lower atom economy in the production process. Removal of the protection groups often requires large volumes of trifluoroacetic acid (TFA) or other strong acids which can result in lower yields and pose a significant risk to the environment.
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- Discovery Sciences, Pfizer Worldwide Research and Development, Groton, CT, USA
After 3 h the resin was washed with binding buffer until no protein was detected, followed by elution with 0.2 mg ml−1 FLAG peptide DYKDDDDK (CPC Scientific Peptide company)
