Different solubilizing ability of cyclodextrin derivatives for cholesterol in Niemann-Pick disease type C treatment

Intracerebroventricular 2-hydroxypropyl-γ-cyclodextrin alleviates hepatic manifestations without distributing to the liver in a murine model of Niemann-pick disease type C

Niemann-Pick disease type C (NPC) is a lysosomal lipid storage disorder characterized by progressive neurodegeneration and hepatic dysfunction. A cyclic heptasaccharide, 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), is currently under clinical investigation for NPC, but its adverse events remain problematic. We previously identified that a cyclic octasaccharide, 2-hydroxypropyl-γ-cyclodextrin (HP-γ-CD), also ameliorated NPC manifestations with higher biocompatibility than HP-β-CD. However, preclinical studies describing the associations between the biodistribution and pharmacodynamics of these compounds, which are essential for clinical application, are still lacking. Here, we investigated these properties of HP-γ-CD by measuring its organ biodistribution and therapeutic effect after systemic and central administration. The effect of HP-γ-CD on disturbed cholesterol homeostasis appeared within several hours after exposure and persisted for several days in NPC model cells and mice. Tissue distribution indicated that only a small fraction of subcutaneously administered HP-γ-CD rapidly distributed to peripheral organs and contributed to disease amelioration. We found that a subcutaneous dose of HP-γ-CD negligibly ameliorated neurological characteristics because it has limited penetration of the blood-brain barrier; however, an intracerebroventricular microdose unexpectedly attenuated hepatic dysfunction without the detection of HP-γ-CD in the liver. These results demonstrate that central administration of HP-γ-CD can indirectly attenuate peripheral manifestations of NPC.

Long-term efficacy of intrathecal cyclodextrin in patients with Niemann-Pick disease type C

BACKGROUND AND OBJECTIVES

Niemann-Pick type C (NPC) is a rare lysosomal storage disease characterized by hepatosplenomegaly and progressive neurological deterioration due to abnormal intracellular cholesterol transport. Cyclic oligosaccharide 2-hydroxypropyl-β-cyclodextrin (HPBCD) is an effective treatment for NPC; however, few reports have shown its long-term efficacy and safety. To demonstrate long-term efficacy and safety of intrathecal HPBCD (IT-HPBCD) treatment for NPC, we herein reports five patients with NPC treated using IT-HPBCD for 4-11 years.

CASES AND RESULTS

Patients' ages at the onset ranged from 1.5 to 20 years. Notably, all patients showed rapid disease progression despite treatment with miglustat before IT-HPBCD treatment. Similarly, some patients showed transient improvement; however, all patients' conditions stabilized after long-term IT-HPBCD therapy. Mild-to-moderate hearing loss was observed in three patients. Furthermore, long-term treatment with IT-HPBCD may suppress neurological deterioration in patients with NPC; however, patients still experience some disease progression.

CONCLUSIONS

Long-term treatment with IT-HPBCD may suppress neurological deterioration in patients with NPC; however, the treatment outcome is dependent on the neurological status at the time of diagnosis, and disease progression is not completely inhibited. Awareness of the disease and newborn screening is needed for earlier disease detection. In addition, further optimization of the treatment protocol and additional treatments are needed to improve patient outcomes.

Impact of cholesterol homeostasis within cochlear cells on auditory development and hearing loss

Cholesterol is the most abundant sterol molecule in mammalian cells, which not only constitutes the cell membrane but also plays essential roles in the synthesis of important hormones, synapse formation, and cell signal transduction. The effect of hypercholesterolemia on hearing has been studied extensively, and multiple studies have demonstrated that hypercholesterolemia is a risk factor for hearing loss. However, the impact of cholesterol homeostasis within auditory cells on peripheral auditory development and maintenance has not been evaluated in detail. Mutations in certain cholesterol metabolism-related genes, such as NPC1, SERAC1, DHCR7, and OSBPL2, as well as derivatives of cholesterol metabolism-related ototoxic drugs, such as β-cyclodextrin, can lead to disruptions of cholesterol homeostasis within auditory cells, resulting in hearing loss. This article aims to review the impact of cholesterol homeostasis within auditory cells on the peripheral auditory function from the following two perspectives: (1) changes in cholesterol homeostasis regulatory genes in various hearing loss models; (2) mechanisms underlying the effects of some drugs that have a therapeutic effect on hearing loss via regulating cholesterol homeostasis. This article aims to summarize and analyze the impact of disruption of cellular cholesterol homeostasis within auditory cells on hearing, in order to provide evidence regarding the underlying mechanisms.

Optimization of Antibacterial Activity and Biosafety through Ultrashort Peptide/Cyclodextrin Inclusion Complexes

Engineered ultrashort peptides, serving as an alternative to natural antimicrobial peptides, offer benefits of simple and modifiable structures, as well as ease of assembly. Achieving excellent antibacterial performance and favorable biocompatibility through structural optimization remains essential for further applications. In this study, we assembled lipoic acid (LA)-modified tripeptide RWR (LA-RWR) with β-cyclodextrin (β-CD) to form nano-inclusion complexes. The free cationic tripeptide region in the nano-inclusion complex provided high antibacterial activity, while β-CD enhanced its biocompatibility. Compared with peptides (LA-RWR, LA-RWR-phenethylamine) alone, inclusion complexes exhibited lower minimum inhibitory concentrations/minimum bactericidal concentrations (MICs/MBCs) against typical Gram-negative/Gram-positive bacteria and fungi, along with improved planktonic killing kinetics and antibiofilm efficiency. The antibacterial mechanism of the nano-inclusion complexes was confirmed through depolarization experiments, outer membrane permeability experiments, and confocal laser scanning microscopy observations. Furthermore, biological evaluations indicated that the hemolysis rate of the inclusion complexes decreased to half or even lower at high concentrations, and cell viability was superior to that of the non-included peptides. Preliminary in vivo studies suggested that the inclusion complexes, optimized for antibacterial activity and biosafety, could be used as promising antibacterial agents for potential applications.

Different solubilizing ability of cyclodextrin derivatives for cholesterol in Niemann-Pick disease type C treatment

BACKGROUND

Niemann-Pick disease type C (NPC) is a fatal neurodegenerative disorder caused by abnormal intracellular cholesterol trafficking. Cyclodextrins (CDs), the most promising therapeutic candidates for NPC, but with concerns about ototoxicity, are cyclic oligosaccharides with dual functions of unesterified cholesterol (UC) shuttle and sink that catalytically enhance the bidirectional flux and net efflux of UC, respectively, between the cell membrane and the extracellular acceptors. However, the properties of CDs that regulate these functions and how they could be used to improve treatments for NPC are unclear.

METHODS

We estimated CD-UC complexation for nine CD derivatives derived from native α-, β-, and γ-CD with different cavity sizes, using solubility and molecular docking analyses. The stoichiometry and complexation ability of the resulting complexes were investigated in relation to the therapeutic effectiveness and toxicity of each CD derivative in NPC experimental models.

FINDINGS

We found that shuttle and sink activities of CDs are dependent on cavity size-dependent stoichiometry and substituent-associated stability of CD-UC complexation. The ability of CD derivatives to form 1:1 and 2:1 complexes with UC were correlated with their ability to normalize intracellular cholesterol trafficking serving as shuttle and with their cytotoxicity associated with cellular UC efflux acting as sink, respectively, in NPC model cells. Notably, the ability of CD derivatives to form an inclusion complex with UC was responsible for not only efficacy but ototoxicity, while a representative derivative without this ability negligibly affected auditory function, underscoring its preventability.

CONCLUSIONS

Our findings highlight the importance of strategies for optimizing the molecular structure of CDs to overcome this functional dilemma in the treatment of NPC.