Picomolar concentrations of oligomeric alpha-synuclein sensitizes TLR4 to play an initiating role in Parkinson's disease pathogenesis Craig D Hughes Minee L Choi Mina Ryten Lee Hopkins Anna Drews Juan A Botía Maria Iljina Margarida Rodrigues Sarah A Gagliano Sonia Gandhi Clare Bryant David Klenerman 10779/crick.11371371.v1 https://crick.figshare.com/articles/journal_contribution/Picomolar_concentrations_of_oligomeric_alpha-synuclein_sensitizes_TLR4_to_play_an_initiating_role_in_Parkinson_s_disease_pathogenesis/11371371 Despite the wealth of genomic and transcriptomic data in Parkinson's disease (PD), the initial molecular events are unknown. Using LD score regression analysis, we show significant enrichment in PD heritability within regulatory sites for LPS-activated monocytes and that TLR4 expression is highest within human substantia nigra, the most affected brain region, suggesting a role for TLR4 inflammatory responses. We then performed extended incubation of cells with physiological concentrations of small alpha-synuclein oligomers observing the development of a TLR4-dependent sensitized inflammatory response with time, including TNF-α production. ROS and cell death in primary neuronal cultures were significantly reduced by TLR4 antagonists revealing that an indirect inflammatory mechanism involving cytokines produced by glial cells makes a major contribution to neuronal death. Prolonged exposure to low levels of alpha-synuclein oligomers sensitizes TLR4 responsiveness in astrocytes and microglial, explaining how they become pro-inflammatory, and may be an early causative event in PD. 2019-12-16 17:43:39 Aggregation Alpha-synuclein Innate immunity Parkinson’s disease TLR4 Gandhi - sec 1103 Clinical Sciences 1109 Neurosciences Neurology & Neurosurgery