Abstract
The human genes for interleukin 13 (IL-13) and its receptor alpha 1 (IL-13Rα1) are in chromosomal regions associated with Parkinson's disease (PD). The interaction of IL-13 with its receptor increases the susceptibility of mouse dopaminergic neurons to oxidative stress. We identified two rare single SNPs in IL13 and IL13RA1 and measured their cytotoxic effects. rs148077750 is a missense leucine to proline substitution in IL13. It was found in individuals with early onset PD and no other known monogenic forms of the disease and is significantly linked with PD (Fisher's exact test: p-value = 0.01, odds ratio = 14.2). rs145868092 is a leucine to phenylalanine substitution in IL13RA1 affecting a residue critical for IL-13 binding. Both mutations increased the cytotoxic activity of IL-13 on human SH-SY5Y neurons exposed to sublethal doses of hydrogen peroxide, t-butyl hydroperoxide or RLS3, an inducer of ferroptosis. Our data show that both rs148077750 and rs145868092 conferred a gain-of-function that may increase the risk of developing PD.