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

ABSTRACT

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.