Nanoparticle-mediated enzyme replacement therapy and autophagy modulation in Krabbe disease

Krabbe disease (KD) is a rare, rapidly progressing childhood leukodystrophy triggered by deficit of the lysosomal enzyme galactosyl-ceramidase (GALC) and characterized by the accumulation of the cytotoxic sphingolipid psychosine in the nervous system. No resolutive cure is currently available for this lysosomal storage disorder (LSD), and treatment is symptomatic and supportive only. Enzyme replacement therapy (ERT) would be a very promising choice to treat KD, but the presence of the blood-brain barrier forbids GALC translocation into the central nervous system (CNS). To overcome this issue, we encapsulated GALC in poly-lactic-co-glycolide nanoparticles (NPs) functionalized with CNS targeting ligands. We demonstrated that our NPs are uptaken in lysosomes and can restore the enzymatic activity in KD cells. Then, we successfully tested our formulations in the Twitcher (TWI) mouse, the spontaneous KD murine model. We reported enzymatic activity measurements in the nervous system and in accumulation districts upon single intraperitoneal injections, demonstrating activity recovery in the brain up to the unaffected mice level. Nevertheless, the recent literature indicates that GALC-deficiency correction might not be sufficient to completely rescue the KD phenotype, suggesting that pathways not yet taken into account could be implicated in KD pathogenesis. Autophagy, for instance, is a vital lysosomal pathway found altered in different LSDs, neurodegenerative conditions and cancer. Here, for the first time, we studied autophagy in two KD cellular models and in the TWI mouse. We demonstrated the presence of a dysregulation at the level of fundamental autophagic markers, suggesting that autophagy might concur in the pathogenesis of KD. We also demonstrated that autophagy stimulation has positive effects on cell viability and on protein aggregates accumulation in vitro, laying the basis for testing autophagy activators in vivo. All data, in the end, open the perspective for the possible usage of autophagy modulation in combination with a main GALC-deficiency correcting therapy to improve the KD phenotypic rescue.

Fabio Taddei (9038) - fabio.taddei@nano.cnr.it
Stefan Heun (9472) - stefan.heun@nano.cnr.it