Single-Cell Level Response of HIV-Specific and Cytomegalovirus-Specific CD4 T Cells Correlate With Viral Control in Chronic HIV-1 Subtype A Infection

HIV-Specific CD8 T Cells Producing CCL-4 Are Associated With Worse Immune Reconstitution During Chronic Infection

BACKGROUND

Immunological nonresponse represents the Achilles heel in the combination antiretroviral therapy (cART) effectiveness, and increases risk of clinical events and death. CD8 T cells play a crucial role in controlling HIV replication, and polyfunctional HIV-specific CD8 T cells have been associated with nonprogressive HIV infection. However, the possible role of polyfunctional CD8 T cells in predicting posttreatment immune reconstitution has not yet been explored. The aim of this study was to identify functional markers predictive of immunological response to cART in chronic HIV-infected patients.

METHODS

A cohort of chronic HIV-infected individuals naive to cART were enrolled in the ALPHA study. CD4/CD8 T-cell subsets, their differentiation/activation, as well as susceptibility to apoptosis were analyzed before and after 12 months of cART. Moreover, CD8 T cells polyfunctional response after HIV antigenic stimulation was also assessed.

RESULTS

Results showed a significant correlation between worse CD4 T-cell restoration and low frequency of naive CD4 T cells, high frequency of effector memory CD4 T cells, and high susceptibility to apoptosis of CD4 T cells all before cART. Moreover, CD8 functional subsets expressing total C-C motif chemokine ligand 4 (CCL-4) or in combination with CD107a and interferon gamma (IFNγ) were negatively associated with immune reconstitution.

CONCLUSIONS

In conclusion, our study shows that a more differentiated phenotype of CD4 T cells and CCL-4-producing CD8 T cells could represent valuable predictors of worse immune reconstitution. These parameters may be used as tools for identifying patients at risk of immunological failure during cART and eventually represent the basis for innovative therapeutic strategies.

High MIP-1β Levels in Plasma Predict Long-Term Immunological Nonresponse to Suppressive Antiretroviral Therapy in HIV Infection

BACKGROUND

HIV-infected patients who fail to reconstitute their CD4 T-cell counts during suppressive antiretroviral therapy (ART) have increased risk of both AIDS-related and non-AIDS-related morbidity and mortality. Improved understanding of immunological nonresponse (INR) is necessary to enable earlier clinical intervention.

METHODS

In a cohort of 112 HIV-infected patients starting ART, we performed a serial analysis of 32 plasma-soluble markers, assessed by multiplex cytokine and enzyme immunoassay. Samples were drawn pre-ART and during the first 3 years of treatment, with a final observation time of 8.4 years (interquartile range, 7.0-10.7 years) on ART. Long-term INR (LT-INR) was defined as failure to reach a CD4 T-cell count >350 cells per microliter. Marker stability was evaluated by parallel analysis of samples from ART-naïve and HIV-seronegative controls.

RESULTS

Baseline CD4 T-cell counts predicted subsequent LT-INR (n = 15) [odds ratio, 1.10 (95% confidence interval: 1.01 to 1.19) pr. 10 cells/μL reduction in CD4 count, P = 0.030] in the cohort as a whole, but not in patients with baseline CD4 counts <200 cells per microliter (n = 78). LT-INR was best characterized by elevated plasma levels of the CC chemokine macrophage inflammatory protein 1β (MIP-1β), both at baseline (pre-ART) and during ART. In patients with baseline CD4 counts <200 cells per microliter, baseline MIP-1β predicted LT-INR [odds ratio 1.23 (95% confidence interval: 1.02 to 1.47) per 10 pg/mL increase in MIP-1β, P = 0.029].

CONCLUSIONS

Elevated pre-ART levels of MIP-1β identified LT-INR patients who started ART at CD4 counts <200. INR was characterized by persistently high MIP-1β during suppressive ART. Thus, MIP-1β may be of use for early identification of LT-INR.

Temporal dynamics of the primary human T cell response to yellow fever virus 17D as it matures from an effector- to a memory-type response

The live attenuated yellow fever virus (YFV) 17D vaccine provides a good model to study immune responses to an acute viral infection in humans. We studied the temporal dynamics, composition, and character of the primary human T cell response to YFV. The acute YFV-specific effector CD8 T cell response was broad and complex; it was composed of dominant responses that persisted into the memory population, as well as of transient subdominant responses that were not detected at the memory stage. Furthermore, HLA-A2- and HLA-B7-restricted YFV epitope-specific effector cells predominantly displayed a CD45RA(-)CCR7(-)PD-1(+)CD27(high) phenotype, which transitioned into a CD45RA(+)CCR7(-)PD-1(-)CD27(low) memory population phenotype. The functional profile of the YFV-specific CD8 T cell response changed in composition as it matured from an effector- to a memory-type response, and it tended to become less polyfunctional during the course of this transition. Interestingly, activation of CD4 T cells, as well as FOXP3(+) T regulatory cells, in response to YFV vaccination preceded the kinetics of the CD8 T cell response. The present results contribute to our understanding of how immunodominance patterns develop, as well as the phenotypic and functional characteristics of the primary human T cell response to a viral infection as it evolves and matures into memory.