PARKIN modifies peripheral immune response and increases neuroinflammation in active experimental autoimmune encephalomyelitis (EAE)

Neuroinflammation plays an important role in the pathogenesis of several neurodegenerative disorders. To elucidate the effects of the mitophagy-related gene Parkin on neuroinflammation, we used a mouse model of experimental autoimmune encephalomyelitis (EAE). Female Parkin−/− and female wild type control mice were immunized with myelin oligodendrocyte glycoprotein to develop active EAE. Compared to the wild type controls, the Parkin−/− mice showed an earlier onset and greater severity of EAE with a greatly increased number of CD8αβ+TCRαβ+ T cells in the spleen and brain as well as a stronger T-cell proliferative response and an altered cytokine secretion in splenocytes. Furthermore, the Parkin−/− mice showed massive recruitment of monocytes/macrophages and activated microglia in the spinal cord during the acute phase of the disease. They also showed accumulation of microglia co-expressing M1 and M2 markers in the brain and a strong over-expression of A1 reactive astrocytes in the spinal cord. Furthermore, the Parkin−/− mice that developed persistent disease exhibited reduced glial cell numbers and abnormalities in mitochondrial morphology. Our study sheds light on the role of PARKIN protein in modulating peripheral immune cells-mediated immunity during EAE, highlighting its importance in neuroinflammation, and thus elucidating its potential in the development of novel neuroprotective therapies.