β-Cyclodextrin-threaded biocleavable polyrotaxanes ameliorate impaired autophagic flux in Niemann-Pick type C disease

Area of Science:

• Biochemistry
• Cell Biology
• Pharmacology

Background:

• Niemann-Pick type C (NPC) disease involves cholesterol buildup and impaired autophagy, hindering autophagosome-lysosome fusion.
• Existing therapies like hydroxypropyl-β-cyclodextrin (HP-β-CD) show limitations in addressing autophagy dysfunction.
• Biocleavable polyrotaxanes (PRXs) threaded with β-cyclodextrin (β-CD) are a novel therapeutic approach for NPC.

Purpose of the Study:

• To investigate the therapeutic potential of biocleavable PRXs in correcting impaired autophagy in NPC disease.
• To compare the effects of biocleavable PRXs and HP-β-CD on autophagy flux in NPC patient-derived cells.

Main Methods:

• Utilized NPC patient-derived fibroblasts (NPC1 fibroblasts) to model the disease.
• Assessed autophagy flux by quantifying LC3-positive puncta and p62 levels.
• Employed mRFP-GFP-LC3 reporter gene expression to monitor autolysosome formation.

Main Results:

• HP-β-CD treatment exacerbated autophagy impairment in NPC1 fibroblasts, increasing LC3 puncta and p62 levels.
• Biocleavable PRX treatment significantly reduced LC3 puncta and p62 levels in NPC1 fibroblasts.
• PRX treatment facilitated autolysosome formation and promoted autophagic protein degradation via an mTOR-independent pathway.

Conclusions:

• Biocleavable PRXs demonstrate efficacy in restoring impaired autophagy in NPC disease models.
• PRXs offer a dual therapeutic benefit by addressing both cholesterol accumulation and autophagy dysfunction in NPC.
• β-CD-threaded biocleavable PRXs represent a promising therapeutic strategy for Niemann-Pick type C disease.