Direct interaction between Urease B of Helicobacter pylori and TLR2 negatively regulates immune fucntions of macrophages / 中华微生物学和免疫学杂志

Objective:To evaluate the regulatory role and potential mechanism of Urease B(UreB) on macrophages.Methods:Bone marrow-derived macrophages (M0) were stimulated by recombinant UreB protein and then flowcytometry and ELISA were used to detect the apoptosis, polarization and antigen presentation-related biomarkers expression. CD4 + T cell co-culture assay, CFSE stain and flowcytometry were used to evaluate the impacts of UreB on antigen presentation capacity of macrophages. Truncated UreB protein, NanoBiT assay and co-immunoprecipitation were used to identify the binding sites of UreB to TLR2. Results:UreB promoted apoptosis and skewed macrophages from M1 to M2 in the presence of M1-inducer LPS. Moreover, UreB inhibited the expression of antigen presentation biomarkers, MHCⅡ and CD86 on macrophages, and further inhibited the proliferation and IFN-γ expression of CD4 + T cells. Molecular analyses revealed that the binding between seven carboxy-terminal amino acid residues of UreB and TLR2 were required for the UreB-mediated inhibitory effects. Conclusions:The findings in this study demonstrate that UreB mainly depends on the binding between seven carboxy-terminal amino acid residues and TLR2 to perform immune-suppressive activities, and which may provide valuable information for the design and optimization of UreB-based vaccines against Helicobacter pylori infection.

Synthesis of multiple antigenic peptide vaccine based on predominant epitopes of Helicobacter pylori UreB protein and immunoprotection of the vaccine / 中华微生物学和免疫学杂志

ObjectiveTo generate a prokaryotic expression system of series predominant epitopes (UreB322 and UreB527) of Helicobacter pylori UreB protein,and to synthesize a multiple antigenic peptide (MAP) vaccine by linking both the two epitopes with a peptide carrier (Poly-Asp-Lys),and to determine the immunogenicity and immunoprotection of the MAP vaccine.MethodsLinking primer PCR was performed to generate an enterokinase(EK) site-containing series UreB322 and UreB527 epitope encoding gene for construction of its prokaryotic expression system.The expressed target recombinant fusion protein 8 ×[rEK-UreB322-EK-UreB527-EK] was hydrolyzed with EK and then rUreB322-EK and rUreB527-EK epitope peptides were extracted using a Sephadex G-25 column.rUreB322-EK,rUreB527-EK and Poly-Asp-Lys were linked using carbodiimide method to produce a MAP vaccine (MAP-rUreB322/B527).The antigenicity and immunoreactivity of each of the two epitope peptides and MAP-rUreB322/527 were determined by ELISA and Western blot assay.An animal H.pylori strain SS1-infected model in BALB/c mice was used to detect the immunoprotection of MAP-rUreB322/527.ResultsAn octuple-repeated series UreB322-UreB527 encoding gene and its prokaryotic expression system were obtained.The yield of target fusion protein 8×[rEKUreB322-EK-rUreB527-EK] was as high as 48％ of the total bacterial proteins.EK hydrolyzed the target fusion protein completely into rUreB322-EK and rUreB527-EK peptides.The linking ratio of rUreB322-EK,rUreB527-EK and Poly-Asp-Lys was as high as 92.5％.The antibody against whole cell of H.pylori and rUreB-IgG could recognize and combine with the rUreB322-EK,rUreB527-EK or MAP-rUreB322/527.The specific serum antibody level in MAP-rUreB322/527-immunized mice was significantly higher than that in rUreB-immunized mice (P＜0.05).The immunoprotective rates(83.3％ and 91.7％ ) by immunization with50 or 100 μg MAP-rUreB322/527 in the H.pyloristrain SSI-infected mice were significantly higher that those(d1.7％ and 50.0％ ) by immunization with equal rUreB(P＜0.05).ConclusionAn gene composed for encoding a repeated series predominant epitopes of H.pylori UreB protein and its prokaryotic expression system are successfully generated in this study.MAP-rUreB322/527,the multiple antigenic peptide vaccine based on the two predominant epitopes of UreB,can noticeably increase the immunoprotection in H.py/or/infected mice.

Immune response to pT-ureB and pT-hpaA DNA vaccine in mice / 第三军医大学学报

Objective To investigate and compare the humoral immune response induced by eukaryotic expression plasmid pTCAEureB (pTureB)and pTCAEhpaA (pThpaA) injected intramuscularly in mice. Methods The ureB gene fragment was inserted into a eukaryotic expression vector pTCAE, and pTCAEureB was constructed. A total of 60 BALB/c mice were randomly assigned to be immunized by intramuscular injection of blank plasmid pTCAE, plasmid pTureB and pThpaA (n=20 in each group). Titers of specific IgG antibody in serum of each group were detected through ELISA respectively on week 2, 4, 6 after immunization. Results Specific IgG were observed in pTureB and pThpaA immunized groups and titers of antibody increased as time prolonged. IgG level was significantly higher in pT-ureB immunized group than in pT-hpaA group on week 6 after immunization. Conclusion Plasmid pT-ureB possesses good immunogenicity and induces a higher immune response than pT-hpaA.

High efficient expression of GST-hureb1 and generation of anti hureb1 antibody / 中国免疫学杂志

Objective:To construct high level prokaryotic cell expression vector carrying human upstream regulatory element binding protein1 (hureb1) gene for producing GST hureb1 fusion protein and generating anti hureb1 antibody Methods: After the Xho I/Not I fragment from hureb1 open reading frame was recombined into the prokaryotic expression vector pGEX 4T 2, the vector was transformed into E coli BL21(DE3) strain and induced with IPTG to express the fusion protein, GST hureb1 The crudely isolated fusion protein was applied to immunize rabbit and mouse for generating anti hureb1 polyclonal antibody and monoclonal antibody respectively Results:The prokaryotic expression vector expressing GST hureb1 fusion protein was constructed and induced to produce high level GST hureb1 that was detected up to 33 45% of the total bacterial protein expressed The GST hureb1 fusion protein immunizing animals generated high titer and specific anti hureb1 antibodies Conclusion:Recombinant hureb1 protein and anti hureb1 antibodies can be used to analyze the biological functions of hureb1