Fatty-acid-based antimiR-23b delivery in the DMSXL model: A potential therapeutic strategy for brain dysfunction in myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is a severe neuromuscular disorder caused by CTG repeat expansions in the DMPK gene, leading to the formation of toxic RNA foci that sequester essential splicing regulators MBNL1/2. Beyond muscle impairment, DM1 affects also the brain, leading to significant cognitive deficits, behavioral abnormalities, and intellectual disabilities. This study evaluates the therapeutic potential of the lipid-conjugated antimiR-23b, X82108, designed to promote MBNL1/2 upregulation through inhibition of miR-23b. Systemic administration of X82108 in mice and non-human primates efficiently crosses the blood-brain barrier, increasing MBNL1 in the brain. In DMSXL transgenic mice, treatment increases Mbnl1/2, reduces toxic DMPK, and restores normal splicing patterns across all brain regions. These molecular improvements correlate with improved behavioral outcomes, including reduced impulsivity and normalized exploratory activity. Collectively, the findings highlight X82108 as a promising systemic therapy for DM1, targeting not only muscular features as we have previously shown but also DM1-related CNS alterations.