Regulatory T cell abundance and activation status before and after priming with HIVIS-DNA and boosting with MVA-HIV/rgp140/GLA-AF may impact the magnitude of the vaccine-induced immune responses

RM Chissumba, A Luciano, E Namalango, A Bauer, N Bhatt, B Wahren, C Nilsson, C Geldmacher, G Scarlatti, I Jani, L Kestens, the TaMoVac II group

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Little is known about regulatory CD4 T cells (Tregs) in the context of HIV vaccines. Tregs can be differentiated into resting (FoxP3+CD45RA+– rTregs), activated (FoxP3HighCD45RA−– aTregs) and memory (FoxP3LowCD45RA−– mTregs). Tregs, as CD4 T cells, are also frequent targets for HIV infection. We studied how the abundance and phenotypes of Tregs in terms of activation status and expression of HIV-1 binding molecules would have changed during vaccination in healthy volunteers participating in a phase IIa HIV vaccine clinical trial. Subjects were primed three times with HIVIS-DNA and boosted twice with MVA-CMDR-HIV alone (n = 12) or MVA-CMDR combined with protein CN54rgp140 (n = 13). The proportions of β7 integrin in all CD4 T cells and in the Tregs subset decreased moderately after the final vaccination (p = 0.001 and p = 0.033, respectively) and the rTregs proportion within the total Tregs were also decreased after the final vaccination (p = 0.038). All these proportions returned to normal values within the three months after the final vaccination. The magnitude of HIV-Envelope-specific IFNγ + T cells after vaccination (r = 0.66; p = 0.021) correlated directly with the proportion of Tregs, and correlated inversely correlated with ratios of Th17/Tregs (r = −0.75; p = 0.0057) and Th17/mTregs (r = −0.78; p = 0.0065). Higher titers of IgG gp140 antibodies were observed in subjects with higher mTregs proportions (r = 0.52; p = 0.022). Interestingly, pre-vaccination levels of mTregs correlated with vaccine-induced Env-binding antibodies (r = 0.57; p = 0.01) and presence of neutralizing antibodies (r = 0.61; p = 0.01), while the pre-vaccination Th17/mTregs ratio correlated inversely with the magnitude of cellular IFN-γ ELISpot responses (r = −0.9; p = 0.002). Taken together, these results suggest that pre- and post-vaccination Tregs, their activation status, the Th17/Tregs ratio and other host factors affecting Treg abundance, have an impact on the magnitude of HIV vaccine-induced immune responses. Moreover, the DNA-HIVIS/MVA-HIV regimen, alone or in combination with CN54rgp140 induced moderate and temporary alterations of the Tregs activation status. We also show a decrease in expression of the HIV-1 ligand β7 integrin on Tregs and all CD4 T cells. © 2018 Elsevier GmbH
Original languageEnglish
Pages (from-to)792-801
Number of pages10
JournalImmunobiology
Volume223
Issue number12
DOIs
Publication statusPublished - 2018

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