Takeshita Hikaru, Watanabe Eri, Norose Yoshihiko, Ito Yasuhiko, Takahashi Hidemi
Department of Microbiology and Immunology, Nippon Medical School.
Department of Pediatrics, Nippon Medical School.
Biomed Res. 2019;40(2):87-95. doi: 10.2220/biomedres.40.87.
Helicobacter pylori (H. pylori) urease is a key protein for persistent infection of the bacteria in the stomach. Although H. pylori generally induce anti-H. pylori-specific antibodies (Abs), these Abs do not usually work for eradication or prevention of the H. pylori infection. In our previous study, we identified a linear epitope composed of 19-mer peptides termed UB-33, CHHLDKSIKEDVQFADSRI, within the large subunit of H. pylori urease. Anti-UB-33-specific Abs neutralized the enzymatic activity of H. pylori urease in vitro. In the present study, we evaluated the effect of immunization of BALB/c mice with H. pylori UB-33 peptide. After confirming the production of anti-UB-33-specific Abs, mice were challenged orally with H. pylori Sydney Strain-1 (SS-1). Mice producing anti-UB-33-specific Abs were not infected with SS-1, and the amount of SS-1 isolate in their stomach was significantly reduced. Also, the urease-negative mutant of H. pylori, HPP1801, did not colonize in the stomach, indicating that H. pylori urease was a critical element for infection of H. pylori in the gastric mucosa. Moreover, mice producing UB-33-specific Abs apparently suppressed H. pylori infection in the stomach where anti-UB-33 Abs were secreted in the gastric juice, indicating that H. pylori colonization was inhibited in the presence of anti-UB-33 Abs. In addition, the neutralization activity of sera from mice immunized with purified urease was less potent than that in the sera from mice immunized with UB-33. Furthermore, the recognition of epitope UB-33 was mediated through Toll-like receptor 2 (TLR2) on the B-1 cells using TLR2-knockout BALB/c mice in vivo. These results indicate that liner peptide UB-33 should be used for immunization to induce neutralizing Abs instead of purified H. pylori urease to prevent H. pylori infection and their colonization in the stomach.
幽门螺杆菌(H. pylori)脲酶是该细菌在胃中持续感染的关键蛋白。尽管幽门螺杆菌通常会诱导产生抗幽门螺杆菌特异性抗体(Abs),但这些抗体通常无法用于根除或预防幽门螺杆菌感染。在我们之前的研究中,我们在幽门螺杆菌脲酶的大亚基中鉴定出一个由19肽组成的线性表位,称为UB-33,序列为CHHLDKSIKEDVQFADSRI。抗UB-33特异性抗体在体外中和了幽门螺杆菌脲酶的酶活性。在本研究中,我们评估了用幽门螺杆菌UB-33肽免疫BALB/c小鼠的效果。在确认产生抗UB-33特异性抗体后,小鼠经口感染幽门螺杆菌悉尼菌株1(SS-1)。产生抗UB-33特异性抗体的小鼠未被SS-1感染,其胃中SS-1分离株的数量显著减少。此外,幽门螺杆菌的脲酶阴性突变体HPP1801未在胃中定植,这表明幽门螺杆菌脲酶是幽门螺杆菌在胃黏膜中感染的关键因素。此外,产生UB-33特异性抗体的小鼠明显抑制了胃中幽门螺杆菌的感染,胃中胃液分泌抗UB-33抗体,这表明在抗UB-33抗体存在的情况下,幽门螺杆菌的定植受到抑制。此外,用纯化脲酶免疫的小鼠血清的中和活性比用UB-33免疫的小鼠血清的中和活性弱。此外,在体内使用TLR2基因敲除的BALB/c小鼠表明,表位UB-33的识别是通过B-1细胞上的Toll样受体2(TLR2)介导的。这些结果表明,应该使用线性肽UB-33进行免疫以诱导中和抗体,而不是使用纯化的幽门螺杆菌脲酶来预防幽门螺杆菌感染及其在胃中的定植。