Abstract Body

Our work shows that Parkinson’s disease (PD), related dementias and experimental in vivo models, can be caused by primary pathogenesis in lipid pathways (Isacson et al 2019 Front. Neurol.; Hallett et al 2019 J Neuroinflammation). By copying mechanisms seen in lysosomal storage disorders, such as Gaucher disease and related disorders, in a chronic, age- and dose-dependent manner, glycolipid cell metabolism can lead to PD, neurodegeneration and neuroinflammation. Deficiencies in several lysosomal hydrolases in animal models causes formation of high-molecular weight alpha-synuclein and ubiquitin. Lysosomal enzyme gene therapy in the substantia nigra reduces embedding of alpha-synuclein in lipid compartments and rescues dopaminergic neurons from degeneration (Rocha et al 2015 Neurobio. Dis.; Brekk et al, 2020 Acta. Neuropathol. Comm.).

Disturbed relationships in lipid homeostasis that causes neuropathology to develop over time and with age, includes altered mechanisms of glia-neuron exchange of lipids and inflammatory signals. Neurons are dependent on proper lipid transport to neighboring glia for lipid exchange and disposal of potentially lipotoxic metabolites, producing distinct lipid distribution profiles amongst various cell-types of the central nervous system. Our data shows that intracellular lipids are accumulated in neurons and microglia in the PD substantia nigra, and this is recapitulated by experimental in vivo inhibition of glucocerebrosidase.

These new results are consistent with a paradigm shift where lipid abnormalities are central to or preceding protein changes typically associated with PD and related disorders. Agents or therapies that restore lipid homeostasis between neurons, astrocytes, and microglia could potentially correct PD pathogenesis and disease progression.