High potency of lipid conjugated TLR7 agonist requires nanoparticulate or liposomal formulation

Adam J.R. Gadd, Valeria Castelletto, Elena Kabova, Kenneth Shankland, Yvonne Perrie, Ian Hamley, Alexander J.A. Cobb, F. Greco, Alexander D. Edwards

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Conjugation of small molecule agonists of Toll-like receptor 7 (TLR7) to proteins, lipids, or polymers is known to modulate potency, and the physical form or formulation of these conjugates is likely to have a major effect on their immunostimulatory activity. Here, we studied the effect of formulation on potency of a 1,2‑di‑(9Z‑octadecenoyl)‑sn‑glycero‑3‑phosphoethanolamine (DOPE) conjugated TLR7 agonist (DOPE-TLR7a) alongside assessing physical form using Dynamic Light Scattering (DLS), Nanosight Particle Tracking (NTA) analysis and Small Angle X-ray Scattering (SAXS). A very high potency of DOPE-TLR7a conjugate (EC50 around 9 nM) was observed either when prepared by direct dilution from DMSO or when formulated into 400–700 nm large multilamella liposomes containing dimethyldioctadecylammonium bromide salt (DDA) and DOPE. When prepared by dissolution in DMSO followed by dilution in aqueous culture medium, 93 ± 5 nm nanoparticles were formed. Without dilution from solution in DMSO, no nanoparticles were observed and no immunostimulatory activity could be detected without this formulation step. SAXS analysis of the conjugate after DMSO dissolution/water dilution revealed a lamellar order with a layer spacing of 68.7 Å which correlates with arrangement in groups of 3 bilayers. The addition of another immunostimulatory glycolipid, trehalose‑6,6‑dibehenate (TDB), to DOPE:DDA liposomes gave no further increase in immunostimulatory activity beyond that provided by incorporating DOPE-TLR7a. Given the importance of nanoparticle or liposomal formulation for activity, we conclude that the major mechanism for increased potency when TLR7 agonists are conjugated to macromolecules is through alteration of physical form.

LanguageEnglish
Pages268-276
Number of pages9
JournalEuropean Journal of Pharmaceutical Sciences
Volume123
Early online date24 Jul 2018
DOIs
Publication statusPublished - 15 Oct 2018

Fingerprint

Toll-Like Receptor 7
Dimethyl Sulfoxide
Nanoparticles
Lipids
Liposomes
X-Rays
Trehalose
Glycolipids
Culture Media
Polymers
Salts
Water
Proteins

Keywords

  • conjugation
  • immunostimulatory
  • lipid conjugate
  • liposomes
  • TLR7 agonist

Cite this

Gadd, Adam J.R. ; Castelletto, Valeria ; Kabova, Elena ; Shankland, Kenneth ; Perrie, Yvonne ; Hamley, Ian ; Cobb, Alexander J.A. ; Greco, F. ; Edwards, Alexander D. / High potency of lipid conjugated TLR7 agonist requires nanoparticulate or liposomal formulation. In: European Journal of Pharmaceutical Sciences. 2018 ; Vol. 123. pp. 268-276.
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Gadd, AJR, Castelletto, V, Kabova, E, Shankland, K, Perrie, Y, Hamley, I, Cobb, AJA, Greco, F & Edwards, AD 2018, 'High potency of lipid conjugated TLR7 agonist requires nanoparticulate or liposomal formulation' European Journal of Pharmaceutical Sciences, vol. 123, pp. 268-276. https://doi.org/10.1016/j.ejps.2018.07.048

High potency of lipid conjugated TLR7 agonist requires nanoparticulate or liposomal formulation. / Gadd, Adam J.R.; Castelletto, Valeria; Kabova, Elena; Shankland, Kenneth; Perrie, Yvonne; Hamley, Ian; Cobb, Alexander J.A.; Greco, F.; Edwards, Alexander D.

In: European Journal of Pharmaceutical Sciences, Vol. 123, 15.10.2018, p. 268-276.

Research output: Contribution to journalArticle

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T1 - High potency of lipid conjugated TLR7 agonist requires nanoparticulate or liposomal formulation

AU - Gadd, Adam J.R.

AU - Castelletto, Valeria

AU - Kabova, Elena

AU - Shankland, Kenneth

AU - Perrie, Yvonne

AU - Hamley, Ian

AU - Cobb, Alexander J.A.

AU - Greco, F.

AU - Edwards, Alexander D.

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KW - conjugation

KW - immunostimulatory

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KW - TLR7 agonist

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