Modeling neuro-immune interaction in Parkinson’s disease using an iPSC-based autologous in vitro system

Abstract

[eng] Parkinson’s disease (PD) is a chronic, incurable, progressive neurodegenerative disorder pathologically characterized by intracellular aggregates of α-synuclein (α-syn) forming Lewy bodies (LBs) and the loss of dopaminergic (DA) neurons in the substantia nigra (SN). In addition to neurodegeneration, PD is associated with inflammation, both in the periphery and in the brain, suggesting that the adaptive and the innate immune systems may participate in the pathogenesis of the disease. However, the dynamic and context-dependent interaction between brain- resident microglia and CNS-recruited T lymphocytes and their impact on PD onset and/or progression is not yet fully understood. To examine these interactions, in the present study we generated functional dopaminergic neurons and microglia-like cells from induced pluripotent stem cells (iPSC) from patients with PD associated to LRRK2 mutations, the most common cause of genetic PD, along with their gene-corrected isogenic controls. We then isolated T cells from the same LRRK2 PD patient and proved their functionality. Upon co-culture, LRRK2-PD T-lymphocytes induce neurodegeneration in LRRK2-PD dopaminergic neurons, whereas LRRK2-PD microglia-like cells do not. However, dopaminergic cell death began earlier and was exacerbated when DAn were cultured with LRRK2- PD microglia-like cells and patients T cells. Using DAn differentiated from the reporter LRRK2-PD SNCA-FLAG iPSC we demonstrated that the tagged α-syn is captured and phagocytosed by both LRRK2-PD and Iso microglia-like cells. Immunofluorescence analysis revealed that unstimulated LRRK2-PD microglial-like cells exhibit increased HLA class I and II complexes compared to the isogenic counterpart. Upon α-syn stimulation, LRRK2-PD microglia like-cells displayed increased HLA class

II complex within endosomal compartment. Moreover, increased formation of HLA-DR/ α-syn complexes was observed. Overall, these data demonstrate that our human neuro-immune axis PD model is a valuable tool for studying the crosstalk between innate and adaptive immune cells in Parkinson’s disease pathogenesis, with potential implications for developing future interventions.