An In Vivo Approach to Structure Activity Relationship Analysis of Peptide Ligands
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The goals in this study were several-fold. First, to optimize the in vivo phage display methodology by incorporating phage pharmacokinetic properties, to isolate peptides that target the brain microvasculature, and then to build focused libraries to obtain structure activity relationship information in vivo to identify the optimal targeting motif.
Materials and Methods
The blood pharmacokinetics of filamentous and T7 phage were evaluated to choose the optimal platform. A randomized peptide library with a motif CX10C was constructed in T7 phage and used for in vivo panning. Focused peptide libraries around each structural element of the brain-specific peptide were constructed to perform kinetic structure activity relationship (kSAR) analysis in vivo. To determine potential function, sepsis was induced in mice by LPS administration and four hours later the effect of GST-peptide on adhesion of rhodamine-labelled lymphocytes or CFDA-labelled platelets to pial microvasculature was observed by intravital microscopy.
The blood phamacokinetics of T7 was rapid (half-life of 12 min) which aids the clearance of non-specific phage. In vivo panning in brain enriched for isolates expressing the motif CAGALCY. Kinetic analysis of focused libraries built around each structural element of the peptide provided for rapid pharmacophore mapping. The computer modeling data suggested the peptide showed similarities to peptide mimetics of adhesion molecule ligands. GST-CAGALCY but not GST control protein was able to inhibit the rolling and adhesion of labeled platelets to inflamed pial vasculature. GST-CAGALCY had no effect on lymphocyte adhesion.
Incorporating normal blood phamacokinetics of T7 phage into in vivo phage display improves the ability to recover targeting peptide motifs and allows effective lead optimization by kSAR. This approach led to the isolation of a brain-specific peptide, CAGALCY, which appears to function as an effective antagonist of platelet adhesion to activated pial microvasculature.
Key wordsbrain targeting in vivo phage display kinetic structure activity relationship pharmacokinetics platelets
carboxyfluorescein diacetate succinimidyl ester
kinetic structure activity relationship
The authors thank Jie Li and Clara Polizzi for their technical assistance with the intravital microscopy studies and Zhe Li, Shaan Tolani, and Zaid Yusufi for technical assistance with the phage display work. The intravital microscopy studies were supported in part by NIH grant A140667-06 to HvdH.
- 13.J. N. George, J. E. Sadler, and B. Lammle. Platelets: thrombotic thrombocytopenic purpura. Hematology (Am. Soc. Hematol. Educ. Program) 1:315–334 (2002).Google Scholar
- 19.T. M. Allen. Interactions of liposomes and other drug carriers with the mononuclear phagocyte system. In G. Gregoriadis (ed.), Liposomes as Drug Carriers, Recent Trends and Progress, Wiley, Chichester, 1988, pp. 37–50.Google Scholar
- 24.B. K. Blackburn, A. Lee, M. Baier, B. Kohl, A. G. Olivero, R. Matamoros, K. D. Robarge, and R. S. McDowell. From peptide to non-peptide. 3. Atropisomeric GPIIbIIIa antagonists containing the 3,4-dihydro-1H-1,4-benzodiazepine-2,5-dione nucleus. J. Med. Chem. 40:717–729 (1997).PubMedCrossRefGoogle Scholar
- 25.N. J. Dubree, D. R. Artis, G. Castanedo, J. Marsters, D. Sutherlin, L. Caris, K. Clark, S. M. Keating, M. H. Beresini, H. Chiu, S. Fong, H. B. Lowman, N. J. Skelton, and D. Y. Jackson. Selective alpha4beta7 integrin antagonists and their potential as anti-inflammatory agents. J. Med. Chem. 45:3451–3457 (2002).PubMedCrossRefGoogle Scholar
- 26.M. S. Egbertson, C. T. Chang, M. E. Duggan, R. J. Gould, W. Halczenko. G. D. Hartman, W. I. Laswell, J. J. Lynch, R. J. Lynch, and P. D. Manno. Non-peptide fibrinogen receptor antagonists. 2. Optimization of a tyrosine template as a mimic for Arg-Gly-Asp. J. Med. Chem. 37:2537–2551 (1994).PubMedCrossRefGoogle Scholar
- 27.T. R. Gadek, D. J. Burdick, R. S. McDowell, M. S. Stanley, J. C. Marsters Jr., K. L. Paris, D. A. Oare, M. E. Reynolds, C. Ladner, K. A. Zioncheck, W. P. Lee, P. Gribling, W. Dennis, L. G. Presta, and S. C. Bodary. Generation of an LFA-1antagonist by the transfer of the ICAM-1 immunoregulatory epitope to a small molecule. Science 295:1086–1089 (2002).PubMedCrossRefGoogle Scholar
- 30.D. Y. Jackson, C. Quan, R. R. Artis, T. Rawson, B. Blackburn, M. Struble, G. Fitzgerald, K. Chan, S. Mullins, J. P. Burnier, W. J. Fairbrother, K. Clark, M. Berisini, H. Chui, M. Renz, S. Jones, and S. Fong. Protein alpha 4 beta 1 peptide antagonists as potential anti-inflammatory agents. J. Med. Chem. 40:3359–3368 (1997).PubMedCrossRefGoogle Scholar
- 33.I. Sircar, K. S. Gudmundsson, R. Martin, J. Liang, S. Nomura, H. Jayakumar, B. R. Teegarden, D. M. Nowlin, P. M. Cardarelli, J. R. Mah, S. Connell, R. C. Griffith, and E. Lazarides. Synthesis and SAR of N-benzoyl-L-bipheylalanine derivatives: discovery of TR-14035, a dual alpha(4)beta(7)/alpha(4)beta(1) integrin antagonist. Bioorg. Med. Chem. 10:2051–2066 (2002).PubMedCrossRefGoogle Scholar
- 37.Y. C. Martin. Theoretical basis of medicinal chemistry: structure activity relationships and three dimensional structures of small and macromolecules. In Y. C. Martin, V. Austel, and E. Kutter (eds.), Modern Drug Research. Paths to Better and Safer Drugs, Marcel Dekker, New York, 1989, pp 161–216.Google Scholar
- 38.Alchemy 2000. Tripos Inc., St Louis, Missouri, http://www.tripos.com.
- 39.ArgusLab 4.0.1 Mark A. Thompson, Planaria Software LLC, Seattle, WA http://www.arguslab.com.