Functionality of CD8+ T-cells in subjects under cART: implications on cure strategies
Date
2018-08
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Abstract
Background: Reaching HIV cure will largely depend on the capacity of HIV-specific memory CD8+ T-cells (CD8TC) to eliminate the viral reservoir. However, CD8TC response is limited in subjects on cART. Here, we aimed to investigate the phenotype and function of in vitro expanded CD8TCs in HIV+ subjects and the impact of ART initiation timing on these parameters.
Methods & Materials: PBMCs from 28 HIV+ subjects on cART for 1 year were obtained. Twelve initiated treatment during chronic infection (Delayed Treatment, DT) and 16 within four months post-infection (Early Treatment, ET). PBMCs were stimulated with peptides spanning Nef and Gag plus IL-2 during 14 days. ELISPOT (pre and post-expansion) and Flow Cytometry (FC, post-expansion) were performed to assess expanded CD8TC function (CD107a/b, IFN-g, IL-2, MIP-1b and TNF-a) and phenotype (CD45RO, CCR7, CD95 and PD1). Data was analyzed using non-parametric statistics.
Results: Magnitude of ELISPOT responses increased after expansion by 103 times (p < 0.002), in both groups, being this effect more pronounced in CD8TCs, compared to CD4TCs (p < 0.0001), as confirmed by FC. Cells showed higher avidity after stimulation (evidenced by greater spot sizes, p < 0.002). DT subjects displayed a broader response to HIV than ET, after expansion. ET group had a significantly higher proportion of monofunctional degranulating CD8TCs (CD107a/b+), when challenged against Gag peptides (p = 0.037) compared to DT. Contrary, DT group showed higher polyfunctionality (p = 0.009). In both groups, CD4TC responses were of lesser magnitude compared to CD8TCs and predominantly monofunctional. Bulk and HIV-specific CD8TC phenotype varied significantly between groups: ET subjects showed a preservation of stem and central memory cells while DT showed a fully-differentiated profile (p < 0.005). When analyzing memory distribution within PD1+CD8+ cells, terminal effector were the most frequent subpopulation in DT and effector memory cells in ET individuals; evidencing a differential cell exhaustion profile in both groups.
Conclusion: We demonstrated that HIV-specific CD8TCs could be selectively stimulated and expanded in subjects under ART. We also showed that ART initiation timing has an impact on phenotype and function of CD8TCs, reflecting consequences of longer antigen persistence on immune function. Overall, results presented in this work have important implications for the development of cure strategies aim at boosting CD8TC responses.
Description
Fil: Figueroa MI. Fundación Huésped, Buenos Aires; Argentina
Keywords
CD8-Positive T-Lymphocytes, Immunotherapy, Adoptive