Cytokine Profiling in Human iPSC-Derived Dopaminergic Neuronal and Microglial Cultures.

Aside from the degeneration of dopaminergic neurons, inflammation is a key component in the movement disorder Parkinson's disease (PD). Microglia activation as well as elevated cytokine levels were observed in the brains of PD patients, but the specific role of microglia in the disease process is unknown. Here, we generate human cellular models by differentiating iPSCs into dopaminergic neurons and microglia. We combine these cells in co-culture to perform cytokine profiling, representing the final functional outcome of various signaling pathways. For this, we used unstimulated conditions and treatment with inflammatory stressors. Importantly, only co-cultures but not the monocultures responded to IL-1β treatment suggesting co-culture-related crosstalk. Moreover, we identified the main types of released cytokines and chemokines in this model system and found a preference for the activation of the chemotaxis pathway in response to all treatments, which informs future studies on the cell-type-specific reaction to inflammatory stimulation. Finally, we detected protein level changes in PD risk factor GPNMB upon stress in microglia, further confirming the link between PD-associated genes and inflammation in human-derived cellular models.