INHIBITORS OF ALPHA-SYNUCLEIN AGGREGATION AND ER STRESS SUPPRESS NEURODEGENERATION IN PARKINSON’S DISEASE ORGANOID MODEL

Accumulation of misfolded alpha-synuclein in the midbrain dopaminergic neurons is the major molecular event underlying Parkinson’s disease (PD). As alpha-synuclein accumulates in the endoplasmic reticulum (ER), ER stress is triggered. Chronic ER stress activation leads to PERK-dependent neuronal cell apoptosis and neurodegeneration. We hypothesize that double inhibition of alpha-synuclein aggregation and ER stress may enhance neuroprotection in PD. Here, we assessed the potential neuroprotective effect of the small-molecule inhibitors of alpha-synuclein aggregation and PERK signaling (anle138b and AMG44, respectively) in a new preclinical model of PD (iPSC-derived midbrain organoids treated with a combination of alpha-synuclein pre-formed fibrils and 6-hydroxydopamine). To determine the effect of the selected compounds on the viability of PD organoids, we performed a CellTiter-Glo 3D assay. We then assessed the effect of the inhibitors on alpha-synuclein aggregation and S129 phosphorylation in PD organoids by immunofluorescence. We found that treatment of PD organoids with anle138b and AMG44 resulted in a significant increase in cell metabolic activity and a significant decrease in aggregated and pS129 alpha-synuclein levels. When combined, the two inhibitory compounds exerted the greatest neuroprotective effect. Our results suggest that combination therapy with the selected small-molecule inhibitors of alpha-synuclein aggregation and ER stress provides neuroprotection in the 3D in vitro model of PD, and may thus represent a new potential disease-modifying strategy for PD. Supported by National Science Centre, Poland (grant no. 2021/43/O/NZ5/02068) and by the Medical University of Lodz, Poland (grant no. 503/1-156-07/503-11-001).