FDA-Approved Secukinumab Alleviates Glial Activation and Immune Cell Infiltration in MPTP-Induced Mouse Model of Parkinson's Disease.

Interleukin-17A (IL-17A) has been implicated in the progression of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). However, the effect of the FDA-approved Secukinumab (SEC), an IL-17A inhibitor, on PD remains unclear. This study aimed to investigate the neuroprotective effect of SEC and its potential mechanisms in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. Male C57BL/6 J mice were mainly assigned to three groups: Sham, MPTP, and MPTP + SEC. Motor coordination was assessed using the climbing rod and rotarod tests. Dopaminergic neurons (TH +) and glial cells (Iba-1 + , GFAP +) in the substantia nigra were evaluated using immunohistochemistry and immunofluorescence. Flow cytometry was used to analyze immune cell populations in the brain and spleen. Inflammatory cytokines and chemokines were quantified using RT-PCR. SEC treatment significantly alleviated the loss of dopaminergic neurons and improved motor coordination in MPTP mice. It also reduced the infiltration of peripheral immune cells, including CD4 + T cells, NK cells, and monocyte-macrophages into the brain. SEC attenuated glial activation (Iba-1 + , GFAP +) and decreased the expression of pro-inflammatory cytokines and chemokines (CCL2, CXCL9), which recruit immune cells into the brain. These results suggest that Secukinumab protects dopaminergic neurons and attenuates neuroinflammation in MPTP-induced model. SEC treatment in PD might be an effective therapeutic approach for clinical application in the future. HIGHLIGHTS: • Secukinumab reduces the loss of dopaminergic neurons and axons in MPTP mice. • Secukinumab inhibits the infiltration of peripheral immune cells into the brain in MPTP mice. • Secukinumab inhibits the activation of glial cells and reduces neuroinflammation in MPTP mice.