UreB immunodominant epitope-specific CD8+ T-cell responses were beneficial in reducing gastric symptoms in Helicobacter pylori-infected individuals.

Abstract

Although Helicobacter pylori is recognized as an extracellular infection bacterium, it can lead to an increase in the number of CD8+ T cells after infection. At present, the characteristics of H.pylori antigen-specific CD8+ T cells and the epitope response have not been elucidated. This study was focused on putative protective antigen UreB to detect specific CD8+ T-cell responses in vitro and screen for predominant response epitopes. The PBMCs collected from H.pylori-infected individuals were stimulated by UreB peptide pools in vitro to identify the immunodominant CD8+ T-cell epitopes. Furthermore, their HLA restriction characteristics were detected accordingly by NGS. Finally, the relationship between immunodominant responses and appearance of gastric symptoms after H.pylori infection was conducted. UreB-specific CD8+ T-cell responses were detected in H.pylori-infected individuals. Three of UreB dominant epitopes (A-2 (UreB443-451 : GVKPNMIIK), B-4 (UreB420-428 : SEYVGSVEV), and C-1 (UreB5-13 : SRKEYVSMY)) were firstly identified and mainly presented by HLA-A*1101, HLA-B*4001 and HLA-C*0702 alleles, respectively. C-1 responses were mostly occurred in H.pylori-infected subjects without gastric symptoms and may alleviate the degree of gastric inflammation. The UreB dominant epitope-specific CD8+ T-cell response was closely related to the gastric symptoms after H.pylori infection, and the C-1 (UreB5-13 ) dominant peptides may be protective epitopes.