Fig. 1

Mn²⁺ activated STING pathway and promoted dendritic cell (DC) maturation. a–c Western blotting assays and ELISAs exploring the effect of Mn²⁺ treatment on STING pathway in human monocyte-derived DCs (MoDCs) and murine bone marrow-derived DCs (BMDCs). After 1 mM Mn²⁺ or other divalent cations including Ca²⁺ and Mg²⁺ treatment for 24 h, the levels of p-STING, STING, p-TBK1, TBK1, p-IRF3, and IFN-β were measured. d–e The dose-dependent effect and toxicity of Mn²⁺ in vitro. Human MoDCs and murine BMDCs were treated with different concentrations of Mn²⁺ for 24 h. The IFN-β concentration in the supernatant was measured by ELISA, and the viability of MoDCs and BMDCs was determined by AO/PI double staining (n = 2 technical replicates). f–i Flow cytometry assays showed that Mn²⁺ promoted DC maturation. After 1 mM Mn²⁺ or 20 ng/ml LPS (positive control) treatment for 24 h, the mean fluorescence intensities (MFIs) of CD80, CD86, and HLA-DR on human MoDCs were measured. After 0.5 mM Mn²⁺ or 20 ng/ml LPS treatment for 24 h, the MFIs of CD80, CD86, and I-A/I-E on murine BMDCs were measured (n = 3 technical replicates). *p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001 denote the significant difference relative to the last group when not marked with lines. MoDC: monocyte-derived dendritic cell; BMDC: bone marrow-derived dendritic cell; MFI: mean fluorescence intensity