Phenotypic and functional differences of HBV core-specific versus HBV polymerase-specific CD8+ T cells in chronically HBV-infected patients with low viral load

Schuch, Anita, Salimi Alizei, Elahe, Heim, Kathrin, Wieland, Dominik, Kiraithe, Michael Muthamia, Kemming, Janine, Llewellyn-Lacey, Sian, Sogukpinar, Özlem, Ni, Yi, Urban, Stephan, Zimmermann, Peter, Nassal, Michael, Emmerich, Florian, Price, David A. ORCID: https://orcid.org/0000-0001-9416-2737, Bengsch, Bertram, Luxenburger, Hendrik, Neumann-Haefelin, Christoph, Hofmann, Maike and Thimme, Robert 2019. Phenotypic and functional differences of HBV core-specific versus HBV polymerase-specific CD8+ T cells in chronically HBV-infected patients with low viral load. Gut 68 , pp. 905-915. 10.1136/gutjnl-2018-316641

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Abstract

Objective A hallmark of chronic HBV (cHBV) infection is the presence of impaired HBV-specific CD8+ T cell responses. Functional T cell exhaustion induced by persistent antigen stimulation is considered a major mechanism underlying this impairment. However, due to their low frequencies in chronic infection, it is currently unknown whether HBV-specific CD8+ T cells targeting different epitopes are similarly impaired and share molecular profiles indicative of T cell exhaustion. Design By applying peptide-loaded MHC I tetramer-based enrichment, we could detect HBV-specific CD8+ T cells targeting epitopes in the HBV core and the polymerase proteins in the majority of 85 tested cHBV patients with low viral loads. Lower detection rates were obtained for envelope-specific CD8+ T cells. Subsequently, we performed phenotypic and functional in-depth analyses. Results HBV-specific CD8+ T cells are not terminally exhausted but rather exhibit a memory-like phenotype in patients with low viral load possibly reflecting weak ongoing cognate antigen recognition. Moreover, HBV-specific CD8+ T cells targeting core versus polymerase epitopes significantly differed in frequency, phenotype and function. In particular, in comparison with core-specific CD8+ T cells, a higher frequency of polymerase-specific CD8+ T cells expressed CD38, KLRG1 and Eomes accompanied by low T-bet expression and downregulated CD127 indicative of a more severe T cell exhaustion. In addition, polymerase-specific CD8+ T cells exhibited a reduced expansion capacity that was linked to a dysbalanced TCF1/BCL2 expression. Conclusions Overall, the molecular mechanisms underlying impaired T cell responses differ with respect to the targeted HBV antigens. These results have potential implications for immunotherapeutic approaches in HBV cure.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine
Additional Information:	Re-use permitted under CC BY-NC. No commercial re-use.
Publisher:	BMJ Publishing Group Ltd
ISSN:	0017-5749
Date of First Compliant Deposit:	18 February 2019
Date of Acceptance:	31 October 2018
Last Modified:	06 May 2023 02:37
URI:	https://orca.cardiff.ac.uk/id/eprint/119660

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