title: Mechanistically probing lipid-siRNA nanoparticle-associated toxicities identifies Jak inhibitors effective in mitigating multifaceted toxic responses.
abstract: A major hurdle for harnessing small interfering RNA (siRNA) for therapeutic application is an effective and safe delivery of siRNA to target tissues and cells via systemic administration. While lipid nanoparticles (LNPs) composed of a cationic lipid, poly-(ethylene glycol) lipid and cholesterol, are effective in delivering siRNA to hepatocytes via systemic administration, they may induce multi-faceted toxicities in a dose-dependent manner, independently of target silencing. To understand the underlying mechanism of toxicities, pharmacological probes including anti-inflammation drugs and specific inhibitors blocking different pathways of innate immunity were evaluated for their abilities to mitigate LNP-siRNA-induced toxicities in rodents. Three categories of rescue effects were observed: (i) pretreatment with a Janus kinase (Jak) inhibitor or dexamethasone abrogated LNP-siRNA-mediated lethality and toxicities including cytokine induction, organ impairments, thrombocytopenia and coagulopathy without affecting siRNA-mediated gene silencing; (ii) inhibitors of PI3K, mammalian target of rapamycin (mTOR), p38 and IκB kinase (IKK)1/2 exhibited a partial alleviative effect; (iii) FK506 and etoricoxib displayed no protection. Furthermore, knockout of Jak3, tumor necrosis factor receptors (Tnfr)p55/p75, interleukin 6 (IL-6) or interferon (IFN)-γ alone was insufficient to alleviate LNP-siRNA-associated toxicities in mice. These indicate that activation of innate immune response is a primary trigger of systemic toxicities and that multiple innate immune pathways and cytokines can mediate toxic responses. Jak inhibitors are effective in mitigating LNP-siRNA-induced toxicities.
authors.affiliation: Department of RNA Therapeutics, Merck Research Laboratories, West Point, Pennsylvania 19486, USA. weikang_tao@merck.com
authors.forename: Weikang
authors.initials: W
authors.lastname: Tao
authors.forename: Xianzhi
authors.initials: X
authors.lastname: Mao
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Davide
authors.forename: Bruce
authors.initials: B
authors.lastname: Ng
authors.forename: Mingmei
authors.initials: M
authors.lastname: Cai
authors.forename: Paul A
authors.initials: PA
authors.lastname: Burke
authors.forename: Alan B
authors.initials: AB
authors.lastname: Sachs
authors.forename: Laura
authors.initials: L
authors.lastname: Sepp-Lorenzino
mesh_terms: D000818:Animals; D016207:Cytokines / Q000097:blood; D003907:Dexamethasone / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism*; D000077613:Etoricoxib; D005260:Female; D055786:Gene Knockout Techniques; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors; D007371:Interferon-gamma / Q000235:genetics; D015850:Interleukin-6 / Q000235:genetics; D053612:Janus Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics; D008055:Lipids / Q000737:chemistry / Q000633:toxicity; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053758:Nanoparticles; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines / Q000378:metabolism; D034741:RNA, Small Interfering / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000235:genetics; D013450:Sulfones / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D016559:Tacrolimus / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors
chemical_list: D016207:Cytokines; D004791:Enzyme Inhibitors; D015850:Interleukin-6; D008055:Lipids; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines; D034741:RNA, Small Interfering; D047889:Receptors, Tumor Necrosis Factor, Type II; D013450:Sulfones; D003907:Dexamethasone; D007371:Interferon-gamma; D053612:Janus Kinases; D058570:TOR Serine-Threonine Kinases; D051550:I-kappa B Kinase; D048051:p38 Mitogen-Activated Protein Kinases; D016559:Tacrolimus; D000077613:Etoricoxib