Adoptive transfer of mitochondrial antigen-specific CD8+ T-cells in mice causes parkinsonism and compromises the dopamine system
The progressive degeneration of dopamine (DA) neurons drives motor symptoms in Parkinsons disease (PD). Whether this neuronal degeneration is due to cell-autonomous dysfunctions in DA neurons or to death signals generated by other cell types is a key problem to address. Recent evidence suggests that loss of function of the protein PINK1, linked to early-onset forms of PD, enhances the presentation of self-derived mitochondrial antigens, which induces the response of autoreactive CD8+ T cells. Whether mitochondrial antigen-specific CD8+ T cells alone are sufficient to induce nigrostriatal dysfunction has not been directly tested. Here we performed adoptive transfer of mitochondrial antigen-specific CD8+ T cells into wild-type or PINK1-deficient mice. We provide evidence for the entry and persistence of such cells in the brain and show that this leads to levodopa-reversible motor dysfunctions and partial degeneration of the nigrostriatal DA system in both genotypes. These findings establish that brain entry of autoreactive CD8+ T cells is sufficient to drive nigrostriatal degeneration and parkinsonian motor deficits, providing the most direct support to date for the hypothesis that an adaptive immune attack plays a key role in PD-like neurodegeneration.