SERPINA1 activation by RUNX1 drives microglial M2 polarization and reduces neuronal injury in a Parkinson's disease mouse model.

Microglial polarization plays a crucial role in Parkinson's disease (PD). This study explores how serpin family A member 1 (SERPINA1) suppresses neuroinflammation and alleviates neuronal damage in PD. Adeno-associated viruses were injected into mice to manipulate the expression of SERPINA1 or runt-related transcription factor 1 (RUNX1) in the substantia nigra, followed by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) modeling. Behavioral tests, histopathology (HE and Nissl staining), immunohistochemistry (IHC), immunofluorescence, and enzyme-linked immunosorbent assay were conducted to evaluate neuroinflammation and neuronal damage in mice. BV2 microglial cells were infected with lentiviruses overexpressing SERPINA1 and treated with 100 µM 1-methyl-4-phenyl-pyridinium (MPP)(+). MPP(+) increased pro-inflammatory cytokines and iNOS while decreasing anti-inflammatory cytokines and arginase-1 expression in BV2 cells. SERPINA1 and RUNX1 were upregulated in the SN of MPTP-induced mice. RUNX1 bound to the promoter region of SERPINA1 to induce its transcription. SERPINA1 or RUNX1 overexpression alleviated PD-related neuronal damage and neuroinflammation in mice and MPP(+)-induced inflammation in BV2 cells. SERPINA1 knockdown inhibited M2 polarization in the presence of RUNX1 overexpression. Taken together, RUNX1 transcriptionally activates SERPINA1, promoting microglial M2 polarization, suppressing neuroinflammation, and alleviating neuronal damage in PD. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10616-025-00878-5.