Abstract
Therapeutics based on small interfering RNA (siRNA) have promising potential as antiviral and anti-inflammatory agents. To deliver siRNA across cell membranes to reach the RNAi pathway in the cytosol of target cells, non-viral nanoparticulate delivery approaches are explored. Recently, we showed that encapsulation of siRNA in lipid-polymer hybrid nanoparticles (LPNs), based on poly(DL-lactic-co-glycolic acid) (PLGA) and cationic lipid-like materials (lipidoids), remarkably enhances intracellular delivery of siRNA as compared to siRNA delivery with LPNs modified with dioleoyltrimethylammoniumpropane (DOTAP) as the lipid component. However, the potential immune modulation by these cationic lipids remains unexplored. By testing lipidoids and DOTAP for innate immune-receptor-activating properties in vitro, we found that neither lipidoids nor DOTAP activate human Toll-like receptor (TLR) 2, 3, 7, and 9. However, in contrast to DOTAP, lipidoids are strong agonists for TLR4 and activate murine antigen-presenting cells in vitro. This agonistic effect was further confirmed in silico using a prediction model based on crystal structures. Also, lipidoids formulated as lipoplexes or as stable nucleic acid lipid particles, which was the reference formulation for siRNA delivery, proved to activate TLR4. However, by combining lipidoids with PLGA into LPNs, TLR4 activation was abrogated. Thus, lipidoid-mediated TLR4 activation during siRNA delivery may be modulated via optimization of the formulation design.
Highlights
Small interfering RNA holds a highly promising therapeutic potential for the treatment of a variety of diseases via gene silencing.[1,2,3] the physicochemical properties of siRNA often limit its therapeutic efficacy, rendering it unfavorable for efficient intracellular delivery to the RNAi pathway mediating gene silencing in the cytosol of the target cells
To date very few studies have addressed the potential undesired immune activation mediated by siRNA delivery systems
The results clearly demonstrate that bulk lipidoids are able to activate TLR4, inducing a pro-inflammatory environment, in contrast to the commonly used cationic lipid DOTAP
Summary
Small interfering RNA (siRNA) holds a highly promising therapeutic potential for the treatment of a variety of diseases via gene silencing.[1,2,3] the physicochemical properties of siRNA often limit its therapeutic efficacy, rendering it unfavorable for efficient intracellular delivery to the RNAi pathway mediating gene silencing in the cytosol of the target cells. These properties include a relatively large molecular weight and high hydrophilicity as a result of the polyanionic phosphate backbone, leading to negligible cellular membrane permeation. Major drawbacks of commonly applied cationic lipids for siRNA delivery, e.g., 1,2-dioleoyl-3-trimethylammoniumpropane (DOTAP), 1,2-di-O-octadecenyl-3-trimethylammonium propane (DOTMA), and dimethyldioctadecyl-ammonium bromide (DDAB), include (1) limited electrostatic interaction with siRNA as a result of the single quaternary ammonium head group (as opposed to structures containing multiple amine functionalities; see below), (2) activation of the innate immune system leading to undesired side effects, and (3) unfavorable biodistribution because of nonspecific tissue distribution and protein binding, eventually resulting in a relatively narrow therapeutic window.[8,9]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
