Alpha-synuclein spreading in M83 mice brain revealed by detection of pathological [alpha]-synuclein by enhanced ELISA

Background The accumulation of misfolded proteins appears as a fundamental pathogenic process in human neurodegenerative diseases. In the case of synucleinopathies such as Parkinson's disease (PD) or dementia with Lewy bodies (DLB), the intraneuronal deposition of aggregated alpha-synuclein ([alpha]S) is a major characteristic of the disease, but the molecular basis distinguishing the disease-associated protein ([alpha]S.sup.D) from its normal counterpart remains poorly understood. However, recent research suggests that a prion-like mechanism could be involved in the inter-cellular and inter-molecular propagation of aggregation of the protein within the nervous system. Results Our data confirm our previous observations of disease acceleration in a transgenic mouse line (M83) overexpressing a mutated (A53T) form of human [alpha]S, following inoculation of either brain extracts from sick M83 mice or fibrillar recombinant [alpha]S. A similar phenomenon is observed following a "second passage" in the M83 mouse model, including after stereotactic inoculations into the hippocampus or cerebellum. For further molecular analyses of [alpha]S.sup.D, we designed an ELISA test that identifies [alpha]S.sup.D specifically in sick mice and in the brain regions targeted by the pathological process in this mouse model. [alpha]S.sup.D distribution, mainly in the caudal brain regions and spinal cord, overall appears remarkably uniform, whatever the conditions of experimental challenge. In addition to specific detection of [alpha]S.sup.D immunoreactivity using an antibody against Ser129 phosphorylated [alpha]S, similar results were observed in ELISA with several other antibodies against the C-terminal part of [alpha]S, including an antibody against non phosphorylated [alpha]S. This also indicated consistent immunoreactivity of the murine [alpha]S protein specifically in the affected brain regions of sick mice. Conclusions Prion-like behaviour in propagation of the disease-associated [alpha]S was confirmed with the M83 transgenic mouse model, that could be followed by an ELISA test. The ELISA data question their possible relationship with the conformational differences between the disease-associated [alpha]S and its normal counterpart. Keywords: Parkinson's, Dementia, Alpha-synuclein, Prion, ELISA