【 Abstract 】 Objective To investigate the effects of Ureaplasma urealyticum GrpE (Uu-GrpE) on the maturation of dendritic cells and the polarization of T cells. Methods Uu-GrpE was expressed and purified, and then identified by Western blot. The cytotoxicity of Uu-GrpE to mouse bone marrow-derived dendritic cells (BMDCs) was analyzed by LDH kit. After stimulating BMDCs with Uu-GrpE, the expression of costimulatory molecules, CD80, CD86 and major histocompatibility complex Ⅱ (MHCⅡ), on the surface of BMDCs was detected by flow cytometry, and ELISA was used to detect the cytokines such as IL-12p70, TNF-α, IL-1β and IL-6. CD4+Naïve T cells were isolated from mouse spleen tissues by magnetic beads. A co-culture system of BMDCs and Naïve T cells was constructed to analyze the effects of GrpE-stimulated mature BMDCs (GrpE-BMDCs) on T cell proliferation and polarization towards Th1/Th2. Mice were immunized with GrpE-BMDCs through the tail vein, and the induced humoral and cellular immune responses were detected by ELISA and flow cytometry. Results Uu-GrpE was successfully express and high purity BMDCs were isolated. Uu-GrpE could stimulate BMDCs to secrete cytokines such as IL-12p70, TNF-α, IL-1β and IL-6 without having cytotoxicity. Uu-GrpE significantly increased the expression of CD80 [mean flourscence indensity (MFI):(324.00±22.11) vs (91.03±10.95),P<0.01], CD86 [MFI:(1 176.00±51.39) vs (217.00±14.93),P<0.01] and MHCⅡ [MFI:(708.70±56.32) vs (185.70±16.77),P<0.01] on BMDCs. Compared to the GrpE-BMDCs only group and GrpE (boiled)-BMDCs+T cell group, the GrpE-BMDCs+T cell group showed significantly increased T cell proliferation [stimulation index:(7.25±0.21) vs (6.55±0.23) and (6.09±0.35),both P<0.05], and dramatically promoted T cell secretion of IL-2 and IFN-γ [IL-2:(145.60±14.67) pg/ml vs(55.92±3.12) pg/ml and (26.05±2.40) pg/ml,P<0.05 and P<0.01;IFN-γ:(267.20±37.80) pg/ml vs(146.70±20.65) pg/ml and(27.84±6.69) pg/ml,both P<0.05]. However, no significant change was observed in the expression of Th2-type cytokines. Moreover, the adoptive transfer of GrpE-BMDCs induced a Th1-type immune response. Conclusions Uu-GrpE could stimulate the maturation and polarization of BMDCs. Moreover, it could induce Th1 immune response as a candidate protein vaccine for Ureaplasma urealyticum. 【 Key words 】 Ureaplasma urealyticum; GrpE; Dendritic cell; Immune response Fund program: Hunan Provincial Innovation Foundation For Postgraduate (CX20200982); Scientific Research Project of Hunan Provincial Health Commission (B2019003); Hunan Science and Technology Innovation Project (2018SK50302); Hunan Provincial Department of Education Project (19B496); Natural Science Foundation of Hunan Province (2020JJ4521) DOI: 10. 3760 / cma. j. cn112309-20210525-00175
