Kupffer cell release of platelet activating factor drives dose limiting toxicities of nucleic acid nanocarriers

Abstract

In vivo nanocarrier-associated toxicity is a significant and poorly understood hurdle to clinical translation of siRNA nanomedicines. In this work, we demonstrate that platelet activating factor (PAF), an inflammatory lipid mediator, plays a key role in nanocarrierassociated toxicities, and that prophylactic inhibition of the PAF receptor (PAFR) completely prevents these toxicities. High-dose intravenous injection of siRNA-polymer nano-complexes (si-NPs) elicited acute, shock-like symptoms (vasodilation and vascular leak) in mice and caused a three-fold increase in blood PAF levels. PAFR inhibition completely prevented these toxicities, indicating PAF activity is a primary driver of systemic si-NP toxicity. Pre-treatment with clodronate liposomes fully abrogated si-NP-associated increases in blood PAF and consequent toxicities, suggesting that nanoparticle uptake by Kupffer macrophages is the source of PAF.Assessment of varied si-NP chemistries further confirmed that toxicity level correlated to relative uptake of the carrier by liver Kupffer cells and that this toxicity mechanism is dependent on the endosome disruptive function of the carrier. Finally, the PAF toxicity mechanism was shown to be generalizable to commercial delivery reagent in vivo-jetPEI ® and an MC3 lipid nanoparticle formulated to match an FDA-approved siRNA nanomedicine. Greater sensitivity to the PAF mechanism occurs in 4T1 tumor-bearing mice, a mammary tumor model known to exhibit increased circulating leukocytes and potential to respond to inflammatory insult. These results establish Kupffer cell release of PAF as a key mediator of in vivo nucleic acid nanocarrier toxicity and identify PAFR inhibition as an effective prophylactic strategy to increase maximum tolerated dose and reduce nanocarrier-associated adverse events. SignificanceNon-viral nucleic acid nanocarriers can enable in vivo gene therapy, but their potential interaction with innate immune cells can cause dose-limiting toxicities. Nanoparticle toxicities .

Polymeric Delivery of Therapeutic Nucleic Acids

“…Zwitterionic polymers are not a catch-all replacement for PEGylation. Most recently, Giorgio and Duvall demonstrated a smaller therapeutic window for MPC than PEG containing polyplexes, requiring a deeper mechanistic understanding of differences between zwitterionic polymers and PEG …”

“…Most recently, Giorgio and Duvall demonstrated a smaller therapeutic window for MPC than PEG containing polyplexes, requiring a deeper mechanistic understanding of differences between zwitterionic polymers and PEG. 602 Erfani and coworkers highlight the effects of zwitterions and their interactions with biomolecules, noting key behavioral differences arising between zwitterions and PEG derivatives in aqueous media. 603 A key behavioral difference between PEG and zwitterionic polymers is their protective action: with wellhydrated and extended polymer chains, the zwitterionic polymer is able to inhibit both aggregation of complexes and degradation of its payload.…”

Structural Optimization of siRNA Conjugates for Albumin Binding Achieves Effective MCL1-Targeted Cancer Therapy

“…Initial clinical success of siRNA was achieved by the FDA-approved, first-in-class medicine patisiran, comprised of siRNA encapsulated in a lipid nanoparticle, preventing siRNA degradation and mediating hepatic delivery for treatment of hereditary transthyretin-mediated amyloidosis 1 . However, nanoparticle formulations are relatively complex to synthesize and are associated with injection reactions 2, 3 , necessitating premedication with corticosteroids and antihistamine, as in the case of patisiran 4 . The challenges of lipid nanoparticle carriers for siRNA delivery might be avoided with a carrier-free delivery system for chemically modified siRNAs.…”

PEGylated Polyester Nanoparticles Trigger Adverse Events in a Large Animal Model of Trauma and in Naı̈ve Animals: Understanding Cytokine and Cellular Correlations with These Events

“…Platelet activating factor (PAF) has been seen to trigger adverse physiologic effects following nanoparticle infusion including vasodilation and increased vascular permeability. 30 To investigate the role of PAF, we performed ELISAs on serum from the blood draws that were performed at 15 min intervals. None of the serum samples across animals or time points had detectable PAF.…”