Neuroprotective and anti-inflammatory effects of the RIPK3 inhibitor GSK872 in an MPTP-induced mouse model of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder triggered by the loss of dopaminergic neurons in the substantia nigra (SN). Recent studies have demonstrated that necroptosis is involved in dopaminergic neuronal cell death and the resulting neuroinflammation. During the process of necroptosis, a necrosome complex is formed consisting of the proteins receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like protein (MLKL). Although the neuroprotective effects of the RIPK1-specific inhibitor necrostatin-1, as well as RIPK3 and MLKL knockout in mice, have been described, the effects of RIPK3 pharmacological inhibitors have not yet been reported in animal models of PD. In the present study, we investigated the neuroprotective effects of GSK872, a specific RIPK3 inhibitor, in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. GSK872 rescued MPTP-induced motor impairment and inhibited tyrosine hydroxylase-positive dopaminergic cell death in the SN and striatum. Additionally, GSK872 inhibited the MPTP-induced increase in the expression of p-RIPK3 and p-MLKL in both the dopaminergic neurons and microglia, as assessed by biochemical and histological analyses. GSK872 further inhibited microglial activation and the expression of inflammatory mediators including NLRP3, interleukin (IL)-1β, IL-6, tumor necrosis factor-alpha, and inducible nitric oxide synthase in the SN region of MPTP mice. Using in vitro experiments, we validated the effects of GSK872 on necroptosis in SH-SY5Y neuronal and BV2 microglial cells. Overall, our results suggest that GSK872 exerts neuroprotective and anti-inflammatory effects, and may thus have therapeutic potential for PD.