Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA, 30332, USA.
Adv Mater. 2020 Jan;32(1):e1904905. doi: 10.1002/adma.201904905. Epub 2019 Nov 19.
Clinical mRNA delivery remains challenging, in large part because how physiology alters delivery in vivo remains underexplored. For example, mRNA delivered by lipid nanoparticles (LNPs) is being considered to treat inflammation, but whether inflammation itself changes delivery remains understudied. Relationships between immunity, endocytosis, and mRNA translation lead to hypothesize that toll-like receptor 4 (TLR4) activation reduced LNP-mediated mRNA delivery. Therefore, LNP uptake, endosomal escape, and mRNA translation with and without TLR4 activation are quantified. In vivo DNA barcoding is used to discover a novel LNP that delivers mRNA to Kupffer cells at clinical doses; unlike most LNPs, this LNP does not preferentially target hepatocytes. TLR4 activation blocks mRNA translation in all tested cell types, without reducing LNP uptake; inhibiting TLR4 or its downstream effector protein kinase R improved delivery. The discrepant effects of TLR4 on i) LNP uptake and ii) translation suggests TLR4 activation can "override" LNP targeting, even after mRNA is delivered into target cells. Given near-future clinical trials using mRNA to modulate inflammation, this highlights the need to understand inflammatory signaling in on- and off-target cells. More generally, this suggests an LNP which delivers mRNA to one inflammatory disease may not deliver mRNA to another.
临床 mRNA 递送仍然具有挑战性，很大程度上是因为生理机能如何改变体内递送过程还未得到充分探索。例如，正在考虑使用脂质纳米颗粒 (LNP) 来治疗炎症，但炎症本身是否会改变递送过程仍研究不足。免疫、内吞作用和 mRNA 翻译之间的关系导致人们假设 Toll 样受体 4 (TLR4) 的激活会降低 LNP 介导的 mRNA 递送。因此，定量研究了 TLR4 激活前后 LNP 的摄取、内涵体逃逸和 mRNA 翻译。体内 DNA 条形码用于发现一种新型 LNP，该 LNP 以临床剂量将 mRNA 递送至库普弗细胞；与大多数 LNP 不同，这种 LNP 并不优先靶向肝细胞。TLR4 激活会阻断所有测试细胞类型中的 mRNA 翻译，而不会减少 LNP 的摄取；抑制 TLR4 或其下游效应蛋白激酶 R 可改善递送。TLR4 对 i）LNP 摄取和 ii）翻译的不同影响表明，TLR4 的激活可以“覆盖”LNP 的靶向性，即使在 mRNA 被递送到靶细胞之后也是如此。鉴于未来即将进行使用 mRNA 调节炎症的临床试验，这凸显了在靶细胞和非靶细胞中理解炎症信号的必要性。更广泛地说，这表明一种将 mRNA 递送至一种炎症性疾病的 LNP 可能无法将 mRNA 递送至另一种疾病。
