Identification of HLA-A2-Restricted Mycobacterial Lipoprotein Z Peptides Recognized by T CellsFrom Patients With ActiveTuberculosis Infection

Yuan-Yong Liu; Wei Sha; Shiqiang Xu; Xu-Wei Gui; Liliang Xia; Ping Ji; Shujun Wang; Guo-Ping Zhao; Xiao Zhang; Yingying Chen; Ying Wang

doi:10.3389/fmicb.2018.03131

Identification of HLA-A2-Restricted Mycobacterial Lipoprotein Z Peptides Recognized by T CellsFrom Patients With ActiveTuberculosis Infection

Front Microbiol. 2018 Dec 21:9:3131. doi: 10.3389/fmicb.2018.03131. eCollection 2018.

Authors

Yuan-Yong Liu^{1

2}, Wei Sha³, Shiqiang Xu², Xu-Wei Gui³, Liliang Xia², Ping Ji², Shujun Wang², Guo-Ping Zhao⁴, Xiao Zhang¹, Yingying Chen², Ying Wang^{2

4}

Affiliations

¹ School of Life Science and Technology, Changchun University of Science and Technology, Changchun, China.
² Department of Microbiology and Immunology, Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
³ Clinic and Research Center of Tuberculosis, Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China.
⁴ Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China.

Abstract

Identification of HLA-restricted peptides derived from mycobacterial antigens that are endowed with high affinity and strong antigenicity is not only of interest in tuberculosis (TB) diagnostics and treatment efficacy evaluation, but might also provide potential candidates for the development of therapeutic vaccines against drug-resistant TB. Our previous work demonstrated that lipoprotein Z (LppZ) displayed high immunogenicity and antigenicity in active TB patients. In the present study, ten HLA-A2-restricted LppZ peptides (LppZp1-10) were predicted by bioinformatics, among which LppZp7 and LppZp10 were verified to possess high affinity to HLA-A2 molecules using T2 cell-based affinity binding assay. Moreover, results from ELISpot assay showed that both LppZp7 and LppZp10 peptides were able to induce more IFN-γ producing cells upon ex vivo stimulation of PBMC from HLA-A2⁺ active TB (ATB) patients as compared to those from healthy controls (HCs). Also, the numbers of LppZp7 and LppZp10-specific IFN-γ producing cells exhibited positive correlations with those of ESAT-6 peptide (E6p) or CFP-10 peptide (C10p) in ATB. Interestingly, stimulation with LppZp7/p10 mixture was able to induce higher intracellular expression of IFN-γ and IL-2 cytokines in CD8⁺ and CD4⁺ T cells from ATB as compared to HC, associated with lower expression of TNF-α in both CD8⁺ and CD4⁺ T cells. Taken together, HLA-A2-restricted LppZp7 and LppZp10 peptides display high immunoreactivity in HLA-matched ATB patients demonstrated by high responsiveness in both CD8⁺ and CD4⁺ T cells. With the ability to induce strong antigen-specific cellular responses, LppZp7 and LppZp10 are of potential value for the future applications in the prevention and control of TB.

Keywords: CD8+ and CD4+ T cells responses; HLA-A2-restricted peptide; antigenicity; mycobacterial lipoprotein Z; tuberculosis.