Abstract
Purpose :
We previously showed that Orai1, the pore forming subunit of the CRAC calcium channel present in mast cells, is upregulated in pollen-induced allergic conjunctivitis in mice. Here we assessed whether an siRNA-based compound targeting orai1 could be a potential therapeutic option for people suffering seasonal allergies
Methods :
In the present set of studies, we have selected the optimal sequence for effective down-regulation of Orai1 in vitro and we have assessed the effect that this sequence may have on cell toxicity, immunogenicity and off-target effect. We have also evaluated the stability of this sequence in different biological fluids (serum and aqueous humor). Finally, the ocular biodistribution of the compound administered in eye drops and its efficacy in a mouse model of allergic conjunctivitis was determined.
Results :
SYL116011 was selected as the most efficient sequence in down-regulating Orai1, causing a decrease that varied between 50-80% depending on the time-point. The reduction of the target gene was observed in absence of alteration of cell viability. In addition, the down regulation of Orai1 was specific as there was no reduction in any other receptor of the Orai family or any potential off-target gene. The stability of the compound in biological fluids showed that the compound was able to maintain its integrity for at least 24h and that there was no activation of the immune system. Following topical ocular administration of a single dose of increasing concentrations of SYL116011, it was found in conjunctiva and cornea five minutes after administration. The concentration of the compound in both eye structures was dose dependent. Finally, SYL116011 treatment of a mouse model of pollen-induced ocular allergy caused a reduction of allergy related clinical signs (chemosis and tearing) and a reduction in the infiltration of mast cells and eosinophils in the conjunctiva; these observations were equivalent to those observed in response to patanol and to some extent better than those observed in response to levocabastine. The reduction in clinical signs and cell infiltration correlated with a reduction in the expression levels of allergy biomarkers in the mouse eye (TLSP and CD137).
Conclusions :
SYL116011 is a potential new treatment for seasonal ocular allergies that should be validated in human trials.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.