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Hao Guo, Mihir Shah, Sarah F Hamm-Alvarez, J. Andrew MacKay; An Elastin-like Polypeptide-based carrier for Cyclosporine A. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3275.
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© ARVO (1962-2015); The Authors (2016-present)
The macrolide immunosuppressant known as Cyclosporine A (CsA) is the active ingredient in an USFDA approved formulation for dry eye disease. The goal of this study is to enhance the therapeutic index of CsA so that it can treat dry eye symptomatic of Sjögren’s Syndrome (SS).
Cyclophilin A (CypA), the cognate target protein of CsA, was fused to an elastin-like polypeptide (ELP) to build a biodegradable carrier for parenteral administration. ELPs exhibit a lower critical solution temperature-like phase separation above a temperature that is a function of variables including concentration, molecular weight, and hydrophobicity. CypA was fused to an ELP with the amino acid sequence (VPGAG)192 to generate CA192. Its phase behavior, structure, loading, stability, and release were explored using optical density, SEC-MALS, reverse phase-HPLC, and Isothermal Titration Calorimetry. In vitro uptake and efficacy were explored in Hela cells by confocal microscopy and in Jurkat cells by inhibition of IL-2 secretion.
The purity and identity of CA192 was confirmed by SDS-PAGE. As intended, CA192 was soluble at physiological temperatures. SEC-MALS revealed that CA192 assembled both nano-aggregates and dimers. The dimer bound CsA to CA192 with a loading ratio of 48.6 ± 4.0% (n=3, mean ± SD). The binding affinity for CsA was 343 ± 175 nM (n=3, mean ± SD) at 25 °C. The CsA release profile fits a one-phase decay with half-life of 954 hr. CA192 was internalized into Hela cell lysosomes, which suggests proteolytic degradation as a possible mechanism for the release and activity. Loaded CsA/CA192 inhibited IL-2 secretion from Jurkat cells with an IC50 of 1.2 ± 4 nM (n=3, mean ± SD), which was comparable to free CsA.
CsA bound to CA192 exhibits equipotent inhibition of IL-2 secretion relative to free CsA. Under sink dialysis, the drug release half-life exceeds one month, which suggests that it may be capable of carrying the drug for extended periods upon parenteral administration. In vitro efficacy and sustained release suggest that a therapeutic dose may reach targets after parenteral administration, including the lacrimal gland.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
CsA/CA192 reduces IL-2 gene secretion from stimulated Jurkat cells comparabe to free CsA. The IC50 of CsA/CA192 was1.2 ± 0.4 nM versus an IC50 of 0.5 ± 0.2 nM for free CsA (n=3, mean ± SD).
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