Intracerebroventricular Administration of a 2'-O-Methyl Phosphorothioate Antisense Oligonucleotide Results in Activation of the Innate Immune System in Mouse Brain

Nucleic Acid Ther. 2018 Apr;28(2):63-73. doi: 10.1089/nat.2017.0705. Epub 2018 Mar 22.


Antisense oligonucleotides (AONs) are versatile molecules that can be used to modulate gene expression by binding to RNA. The therapeutic potential of AONs appears particularly high in the central nervous system, due to excellent distribution and uptake in brain cells, as well as good tolerability in clinical trials thus far. Nonetheless, immune stimulation in response to AON treatment in the brain remains a concern. For this reason we performed RNA sequencing analysis of brain tissue from mice treated intracerebroventricularly with phosphorothioate, 2'-O-methyl modified AONs. A significant upregulation of immune system associated genes was observed in brains of AON treated mice, with the striatum showing largest transcriptional changes. Strongest upregulation was seen for the antiviral enzyme 2'-5'-oligoadenylate synthase-like protein 2 (Oasl2) and Bone marrow stromal antigen 2 (Bst2). Histological analysis confirmed activation of microglia and astrocytes in striatum. The upregulation of immune system associated genes was detectable for at least 2 months after the last AON administration, consistent with a continuous immune response to the AON.

Keywords: 2′-O-methyl; antisense oligonucleotide; immune stimulation; mouse brain.

MeSH terms

  • 2',5'-Oligoadenylate Synthetase / genetics
  • 2',5'-Oligoadenylate Synthetase / metabolism
  • Animals
  • Antigens, CD / genetics
  • Antigens, CD / metabolism
  • Astrocytes / drug effects
  • Brain / drug effects*
  • Brain / pathology
  • Immunity, Innate / drug effects*
  • Infusions, Intraventricular*
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Microglia / drug effects
  • Oligonucleotides, Antisense / administration & dosage*
  • Phosphorothioate Oligonucleotides / administration & dosage*
  • RNA / genetics
  • RNA / metabolism
  • Sequence Analysis, RNA


  • Antigens, CD
  • BST2 protein, mouse
  • Membrane Glycoproteins
  • Oligonucleotides, Antisense
  • Phosphorothioate Oligonucleotides
  • RNA
  • Oasl2 protein, mouse
  • 2',5'-Oligoadenylate Synthetase