Optimisation of LRRK2 inhibitors and assessment of functional efficacy in cell-based models of neuroinflammation

LRRK2IN1 is a highly potent inhibitor of leucine-rich repeat kinase 2 (LRRK2, IC₅₀ = 7.9 nM), an established target for treatment of Parkinson's disease. Two LRRK2IN1 analogues 1 and 2 were synthesised which retained LRRK2 inhibitory activity (1: IC₅₀ = 72 nM; 2: IC₅₀ = 51 nM), were predicted to have improved bioavailability and were efficacious in cell-based models of neuroinflammation. Analogue 1 inhibited IL-6 secretion from LPS-stimulated primary human microglia with EC₅₀ = 4.26 μM. In order to further optimize the molecular properties of LRRK2IN1, a library of truncated analogues was designed based on docking studies. Despite lacking LRRK2 inhibitory activity, these compounds show antineuroinflammatory efficacy at micromolar concentration. The compounds developed were valuable tools in establishing a cell-based assay for assessing anti-neuroinflammatory efficacy of LRRK2 inhibitors. Herein, we present data that IL-1β stimulated U87 glioma cell line is a reliable model for neuroinflammation, as data obtained in this model were consistent with results obtained using primary human microglia and astrocytes.