Apolipoprotein-mimetic nanodiscs reduce lipid accumulation and improve liver function in acid sphingomyelinase deficiency.

Acid sphingomyelinase deficiency (ASMD) is a severe lipid storage disorder caused by the diminished activity of the acid sphingomyelinase enzyme. ASMD is characterized by the accumulation of sphingomyelin in late endosomes and lysosomes leading to progressive neurological dysfunction and hepatosplenomegaly. Our objective was to investigate the utility of synthetic apolipoprotein A-I (ApoA-I) mimetics designed to act as lipid scavengers for the treatment of ASMD. We determined the lead peptide, 22A, could reduce sphingomyelin accumulation in ASMD patient skin fibroblasts in a dose dependent manner. Intraperitoneal administration of 22A formulated as a synthetic high-density lipoprotein (sHDL) nanodisc mobilized sphingomyelin from peripheral tissues into circulation and improved liver function in a mouse model of ASMD. Together, our data demonstrates that apolipoprotein mimetics could serve as a novel therapeutic strategy for modulating the pathology observed in ASMD.

Synaptic resilience is associated with maintained cognition during ageing.

INTRODUCTION: It remains unclear why age increases risk of Alzheimer's disease and why some people experience age-related cognitive decline in the absence of dementia. Here we test the hypothesis that resilience to molecular changes in synapses contribute to healthy cognitive ageing. METHODS: We examined post-mortem brain tissue from people in mid-life (n = 15), healthy ageing with either maintained cognition (n = 9) or lifetime cognitive decline (n = 8), and Alzheimer's disease (n = 13). Synapses were examined with high resolution imaging, proteomics, and RNA sequencing. Stem cell-derived neurons were challenged with Alzheimer's brain homogenate. RESULTS: Synaptic pathology increased, and expression of genes involved in synaptic signaling decreased between mid-life, healthy ageing and Alzheimer's. In contrast, brain tissue and neurons from people with maintained cognition during ageing exhibited decreases in synaptic signaling genes compared to people with cognitive decline. DISCUSSION: Efficient synaptic networks without pathological protein accumulation may contribute to maintained cognition during ageing.