Functional Avidity and IL-2/Perforin Production Is Linked to the Emergence of Mutations within HLA-B*5701–Restricted Epitopes and HIV-1 Disease Progression

Abstract

Viral escape from HIV-1-specific CD8+ T cells has been demonstrated in numerous studies previously. However, the qualitative features driving the emergence of mutations within epitopes are still unclear. In this study, we aimed to distinguish whether specific functional characteristics of HLA-B*5701-restricted CD8+ T cells influence the emergence of mutations in high-risk progressors (HRPs) versus low-risk progressors (LRPs). Single genome sequencing was performed to detect viral mutations (variants) within seven HLA-B*5701-restricted epitopes in Gag (n = 4) and Nef (n = 3) in six untreated HLA-B*5701 subjects followed from early infection up to seven years. Several well-characterized effector markers (IFN-γ, IL-2, MIP-1β, TNF, CD107a and perforin) were identified by flow cytometry following autologous (initial and emerging variant/s) epitope stimulations. This study demonstrates that specific functional attributes may facilitate the outgrowth of mutations within HLA-B*5701-restricted epitopes. A significantly lower fraction of IL-2 producing cells and a decrease in functional avidity and polyfunctional sensitivity were evident in emerging epitope variants compared to the initial autologous epitopes. Interestingly, the HRPs mainly drove these differences, while the LRPs maintained a directed and maintained functional response against emerging epitope variants. In addition, LRPs induced improved cell cycle progression and perforin up-regulation after autologous and emerging epitope variant stimulations in contrast to HRPs. The maintained quantitative and qualitative features of the CD8+ T cell responses in LRPs toward emerging epitope variants provide insights into why HLA-B*5701 subjects have different risks of HIV-1 disease progression.

CD4+ T cells with an activated and exhausted phenotype distinguish immunodeficiency during aviremic HIV-2 infection

“…Interestingly, strong links between elevated frequency of cells expressing PD-1, in combination with CD38 and HLA-DR, was noted with reduced levels of both %CD4 and CD4 count. However, when analyzing %PD-1 + cells separately, there was only an association with %CD4, in line with our earlier observations that CD4/CD8 ratio and %CD4 correlate better with pathological T-cell phenotypes than CD4 count [ 33 ]. The simultaneous assessment of all markers and specific CD4 + T-cell populations using FLOCK analysis also revealed that PD-1-expressing populations, primarily the activated late-differentiated, were associated with low CD4 + T-cell levels in aviremic HIV-2 infection.…”

“…Antibody capture beads (BD Biosciences) were used for compensation and FlowJo 8.8.7 (Tree Star, Ashland, Oregon, USA) for analyses. All manual gatings were based on fluorescence-minus-one gating strategies as described [ 33 , 34 ]. A typical gating strategy to distinguish CD4 + T cells is visualized in Fig.…”

Frequencies of Gag-restricted T-cell escape “footprints” differ across HIV-1 clades A1 and D chronically infected Ugandans irrespective of host HLA B alleles

“…Indisputably, T-cells exert strong selection pressure on HIV-1, generating HLA allele-restricted mutants that evade subsequent T-cell responses [48,49] . Emergence of HLA-B*5701-restricted variants has been linked to superior maintenance of IL-2 and Perforin, and persistence of polyfunctional CD8+ T-cell responses [50] . Superior virological control has been linked to greater functional avidity of the T-cell responses [31] .…”

Perturbed CD8+ T cell TIGIT/CD226/PVR axis despite early initiation of antiretroviral treatment in HIV infected individuals

“…Antibody capture beads (BD Bioscience) were used for single-stain compensation controls. Flow cytometry data were analyzed with FlowJo 8.8.7 (Treestar) and when applicable, fluorescence minus one (FMO) gating strategies were used to set the manual gates93738. A virus-specific response was considered positive when ≥0.05% of the cells produced IFN-γ after background reduction and if the response was larger than twice the negative background signal93738.…”