Fractalkine over expression suppresses α-synuclein-mediated neurodegeneration.

In Parkinson's disease， α-synuclein is known to activate microglia and this activation has been proposed as one of the mechanisms of neurodegeneration. There are several signals produced by neurons that have an anti-inflammatory action on microglia， including CX3CL1 (fractalkine). We have shown that a soluble form of CX3CL1 is required to reduce neuron loss in 1-methyl-4-phenyl-1，2，3，6-tetrahydropyridine (MPTP)-treated mice and that fractalkine agonism can reduce neuron loss in a 6-hydroxydopamine lesion model. Here， we show that fractalkine can reduce α-synuclein-mediated neurodegeneration in rats. Rats that received fractalkine showed abrogated loss of tyrosine hydroxylase and Neu-N staining. This was replicated in animals where we expressed fractalkine from astrocytes with the glial fibrillary acid protein (GFAP) promoter. Interestingly， we did not observe a reduction in MHCII expression suggesting that soluble fractalkine is likely altering the microglial state to a more neuroprotective one rather than reducing antigen presentation.