Motor neuron loss and neuroinflammation in a model of α-synuclein-induced neurodegeneration

Abstract

Mechanisms underlying α-synuclein (αSyn) mediated neurodegeneration are poorly understood. Intramuscular (IM) injection of αSyn fibrils in human A53T transgenic M83 mice produce a rapid model of α-synucleinopathy with highly predictable onset of motor impairment. Using varying doses of αSyn seeds, we show that αSyn-induced phenotype is largely dose-independent. We utilized the synchrony of this IM model to explore the temporal sequence of αSyn pathology, neurodegeneration and neuroinflammation. Longitudinal tracking showed that while motor neuron death and αSyn pathology occur within 2 months post IM, astrogliosis appears at a later timepoint, implying neuroinflammation is a consequence, rather than a trigger, in this prionoid model of synucleinopathy. Initiating at 3 months post IM, immune activation dominates the pathologic landscape in terminal IM-seeded M83 mice, as revealed by unbiased transcriptomic analyses. Our findings provide insights into the role of neuroinflammation in αSyn mediated proteostasis and neurodegeneration, which will be key in designing potential therapies.

Unique α-synuclein pathology within the amygdala in Lewy body dementia: implications for disease initiation and progression

“…1a). Additionally, antibody 3H11 was further tested on transgenic mice containing pathologic aggregates comprised of A53T human αsyn (seeded line M83 [94]) or WT human αsyn (seeded line M20 [91]). As 3H11 does not detect mouse αsyn (that contains the A53T substitution) or A53T human αsyn, no pathology was revealed in the M83 mice using 3H11 whereas extensive LRP was labeled in the M20 mice (Fig.…”

“…8). Other studies have noticed unique relationships between the amygdala and αsyn; for example, injections of pre-formed αsyn fibrils into various mouse models at differing locations invariably lead to amygdala pathology [1, 7, 13, 65–67, 78, 91, 94], and the amygdala uniquely displays immense upregulation of αsyn in relation to alcohol and opiate abstinence following addiction [114]. The studies herein demonstrate that pathologic αsyn within the amygdala in LBD is unique both in its immunohistochemical properties and immunoblotting profile which may differentiate aggregated forms of αsyn in LBD from the more innocuous AD/ALB.…”

“…Hemizygous M83 transgenic mice overexpress human αsyn harboring the A53T mutation and when intra-muscularly seeded with pre-formed αsyn fibrils they accumulate pathologic inclusions that spread throughout most of the neuro-axis [94]. Hemizygous M20 mice overexpress wild type (WT) human αsyn and when intra-cerebrally injected with preformed αsyn fibrils develop extensive αsyn pathology [91].…”

Carboxy‐terminal truncations of mouse α‐synuclein alter aggregation and prion‐like seeding

“…Mice were euthanized with CO 2 , perfused with a heparin/PBS solution, fixed in 70% EtOH/150 m m NaCl, and sectioned as previously described . For immunohistochemical analysis, sections were stained utilizing established methods .…”

“…Mice were euthanized with CO 2 , perfused with a heparin/PBS solution, fixed in 70% EtOH/150 m m NaCl, and sectioned as previously described . For immunohistochemical analysis, sections were stained utilizing established methods . Antigen retrieval was performed utilizing target retrieval solution (Agilent) in a steam bath for 1 h. All antibodies were incubated with tissue overnight at 4°C overnight in block solution (2% FBS in 0.1 m Tris, pH 7.6).…”