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 + Na?ve T cells were isolated from mouse spleen tissues by magnetic beads. A co-culture system of BMDCs and Na?ve 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.
ABSTRACT
Objective To investigate the biological properties of Schistosoma japonicum SjGrpE protein, and to express and purify the recombinant SjGrpE protein and test its immunogenicity. Methods The amino acid composition, molecular weight, hydrophilicity and hydrophobicity, transmembrane region, signal peptide, localization, phosphorylation site, ubiquitination site, glycosylation site, secondary and tertiary structures and B cell epitopes of the SjGrpE protein were predicted using bioinformatics analyses. The SjGrpE gene was amplified using PCR assay using S. japonicum cDNA as a template, double enzyme-digested and linked to the pET28a vector to yield the recombinant plasmid pET28a-SjGrpE. The recombinant plasmid pET28a-SjGrpE was transformed into Escherichia coli BL21, and then IPTG was employed to induce the expression of the target protein, which was purified by nickel ion affinity chromatography. After mice were immunized with the recombinant SjGrpE protein, mouse sera were collected, and the polyclonal antibody against the SjGrpE protein was characterized. Results SjGrpE protein, which was identified as a hydrophilic protein, was predicted to have a molecular weight of approximately 24.3 kDa without transmembrane regions or signal peptides, and locate in the mitochondrion. SjGrpE protein contained 18 phosphorylation sites and 2 ubiquitination sites, but had no glycosylation sites. In addition, SjGrpE protein contained 5 B-cell epitopes. The full length of SjGrpE gene was approximately 660 bp. The recombinant pET28a-SjGrpE plasmid was successfully generated, and the recombinant SjGrpE protein was obtained following the affinity chromatography, which stimulated mice to secrete high-titer antibodies. Conclusions The recombinant SjGrpE protein has been successfully prepared and this recombinant protein has a high immunogenicity, which provides a basis for evaluating its value as a vaccine candidate for S. japonicum infections.