Lutein ameliorates Parkinson's disease by regulating miR-135b-5p/SIRT1 to inhibit microglial M1 polarization and inflammation

The development of Parkinson's disease (PD) is fundamentally linked to neuroinflammation and the overstimulation of microglia. Previous studies suggest that lutein exerts anti-inflammatory effects on the nervous system. This study aimed to investigate the function and mechanism of lutein in ameliorating PD. In this study, we experimentally explored an animal model of MPTP-induced PD and a model of lipopolysaccharide (LPS)-induced BV2 microglial inflammation. Behavioral tests, immunohistochemistry, and immunofluorescence were used to assess animal behavioral capacity and neuronal damage. Western blotting, RTqPCR and ELISA were used to measure the levels of related proteins, genes and inflammatory factors. Dual-luciferase reporter gene assays and RIP detection were conducted to determine the relationship between miR-135b-5p and SIRT1. The results showed that lutein ameliorated behavior disorders and increased the number of TH-positive neurons in MPTP-induced PD mice. Lutein inhibited M1 polarization and inflammation in BV2 cells by decreasing the expression of the M1 markers iNOS and CD86 and the proinflammatory factors TNF-α, IL-β and IL-6 and increasing the expression of the M2 markers Arg-1 and CD206 and the anti-inflammatory factors IL-4 and IL-10. Lutein inhibited LPS-induced M1 polarization in BV2 cells by decreasing miR-30b-5p or activating SIRT1 expression, whereas miR-135b-5p negatively regulated SIRT1, and the knockdown of miR-135b-5p inhibited LPS-induced M1 polarization in BV2 cells by upregulating SIRT1. In conclusion, lutein upregulates SIRT1 expression by inhibiting miR-135b-5p, which in turn inhibits microglial M1 polarization and inflammation, thereby ameliorating PD.