Characterization of Immune Failure by Monocyte Activation Phenotypes in HIV-Infected Patients Receiving Antiretroviral Therapy

Increased early activation of CD56dimCD16dim/- natural killer cells in immunological non-responders correlates with CD4+ T-cell recovery

BACKGROUND

Natural killer (NK) cells play a critical role in suppressing human immunodeficiency virus-1 (HIV-1) infection, but knowledge on whether and how NK cells affect immune reconstitution in HIV-1-infected individuals who receive antiretroviral therapy (ART) is limited.

METHODS

We performed a case-control study with 35 healthy individuals and 66 HIV-1-infected patients including 32 immunological non-responders (INRs) with poor CD4+ T-cell recovery (<500 cells/μL after 4 years of ART) and 34 immunological responders (IRs) with improved CD4+ T-cell recovery (>500 cells/μL after 4 years of ART). NK cell phenotype, receptor repertoire, and early activation in INRs and IRs were investigated by flow cytometry.

RESULTS

A significantly higher proportion of CD56dimCD16dim/- NK cells was observed in INRs than IRs before ART and after 4 years of ART. The number of CD56dimCD16dim/- NK cells was inversely correlated with CD4+ T-cell counts in INRs before ART (r = -0.344, P = 0.050). The more CD69-expressing NK cells there were, the lower the CD4+ T-cell counts and ΔCD4, and these correlations were observed in INRs after ART (r = -0.416, P = 0.019; r = -0.509, P = 0.003, respectively). Additionally, CD69-expressing CD56dimCD16dim/- NK cells were more abundant in INRs than those in IRs (P  = 0.018) after ART, both of which had an inverse association trend towards significance with CD4+ T-cell counts. The expression of the activating receptors NKG2C, NKG2D, and NKp46 on CD56dimCD16dim/- NK cell subsets were higher in IRs than that in INRs after 4 years of ART (all P < 0.01). Strong inverse correlations were observed between CD69 expression and NKG2C, NKG2A-NKG2C+, NKG2D, and NKp46 expression on CD56dimCD16dim/- NK cells in INRs after ART (NKG2C: r = -0.491, P = 0.004; NKG2A-NKG2C+: r = -0.434, P = 0.013; NKG2D: r = -0.405, P = 0.021; NKp46: r = -0.457, P = 0.008, respectively).

CONCLUSIONS

INRs had a larger number of CD56dimCD16dim/- NK cells characterized by higher activation levels than did IRs after ART. The increase in the CD56dimCD16dim/- NK cell subset may play an adverse role in immune reconstitution. Further functional studies of CD56dimCD16dim/- NK cells in INRs are urgently needed to inform targeted interventions to optimize immune recovery.

Increased Frequencies of Myeloid-Derived Suppressor Cells Precede Immunodiscordance in HIV-Infected Subjects

Background

We have previously observed increased levels of inflammatory biomarkers and Th17 as well as Treg cells, but not other T-cell specific alterations, preceding immunodiscordance of successfully-treated HIV-infected subjects. Our hypothesis is that this could be related with potential alterations in myeloid-derived suppressor cells (MDSCs) and/or monocyte subsets.

Methods

We determined the frequencies of MDSCs and monocyte subsets and the expression of several functional markers (CCR2, β7-integrin, IDO, PDL1, CD11b) in HIV-infected subjects before treatment. We additionally analyzed follow-up samples after 24 months of suppressive cART in a subgroup of subjects. Bivariate regressions were performed, and correlations with soluble proinflammatory and bacterial translocation biomarkers, as well as with Th17/Treg ratio and anti-CMV titers were explored.

Results

Increased frequencies of MDSCs, but normal distribution of monocyte subsets, preceded immunodiscordance. The expression of several functional markers, such as CCR2, CD16, CD11b and PDL1, on MDSCs and monocyte subsets was altered in this scenario. MDSC and monocyte-related functional markers were associated with soluble biomarkers and T-cell parameters. Several of these cellular alterations were not restored after 24 months of suppressive cART.

Conclusion

An early immunosuppressive environment, characterized by the expansion of MDSCs and Tregs, precedes immunodiscordance and is related with a highly inflammatory status.

Activated dendritic cells and monocytes in HIV immunological nonresponders: HIV-induced interferon-inducible protein-10 correlates with low future CD4+ recovery

Supplemental Digital Content is available in the text

Objective:

To explore monocyte and dendritic cell immune responses, and their association with future CD4⁺ gain in treated HIV patients with suboptimal CD4⁺ recovery.

Design:

A cross-sectional study of HIV-infected, virally suppressed individuals on antiretroviral therapy for at least 24 months; 41 immunological nonresponders (INRs) (CD4⁺ cell count <400 cells/μl) and 26 immunological responders (CD4⁺ cell count >600 cells/μl). Ten HIV-infected antiretroviral therapy-naive and 10 HIV-negative healthy persons served as controls. CD4⁺ cell counts were registered after median 2.4 and 4.7 years.

Methods:

Monocyte, dendritic-cell and T-cell activation and regulatory T cells (Tregs) were analyzed by flow cytometry. In INR and immunological responder subgroups matched on age and nadir CD4⁺ cell count, upregulation of interferon-inducible protein-10 (IP-10) and indoleamine 2,3-dioxygenase in monocytes and dendritic cells and cytokines in cell supernatants were measured in vitro in peripheral blood mononuclear cells stimulated with aldrithiol-2-inactivated HIV-1.

Results:

The INR group displayed higher spontaneous activation of both monocytes (HLA-DR⁺) and myeloid and plasmacytoid dendritic cells (HLA-DR⁺, CD83⁺ and CD86⁺) compared with immunological responders, and this was associated with increased T-cell activation (CD38⁺HLA-DR⁺), an effector memory T-cell phenotype and activated Tregs. The IP-10 response in monocytes after in-vitro HIV stimulation was negatively associated with prospective CD4⁺ gain. IP-10, indoleamine 2,3-dioxygenase and cytokines levels were comparable between the groups, but inversely correlated with activated Tregs in INRs.

Conclusion:

HIV-infected individuals with suboptimal immune recovery demonstrated more activated monocytes and in particular dendritic cells, compared with patients with acceptable CD4⁺ gain. A high level of HIV-specific IP-10 expression in monocytes may be predictive of future CD4⁺ recovery.

Brief Report: Peripheral Monocyte/Macrophage Phenotypes Associated With the Evolution of Cognitive Performance in HIV-Infected Patients

BACKGROUND

The contribution of monocyte activation in the development of HIV-associated neurocognitive disorders is not completely understood. This study aimed to explore the predictive value of peripheral monocyte/macrophage (M/M) phenotypes on the evolution of cognitive performance in a population of virologically suppressed HIV-infected patients.

SETTING

Prospective, observational, longitudinal study.

METHODS

HIV-1-infected patients with HIV-RNA <50copies/mL for >12 months underwent neuropsychological examination at baseline and after 1 year. Cognitive performance was evaluated using Z-transformed scores, and neurocognitive impairment (NCI) was defined according to Frascati criteria. Peripheral M/M phenotypes (classic CD14CD16, intermediate CD14CD16, and nonclassic CD14CD16) and specific surface activation markers (eg, CD163, CD11b, and CD38) were evaluated using flow cytometry at baseline. Predictive value of peripheral M/M phenotypes on the evolution of cognitive performance over 1-year follow-up was also evaluated.

RESULTS

Overall, 54 patients [85.2% men, median age 50 years (range 27-60 years), 27.8% hepatitis C virus coinfected, 48.1% with past AIDS-defining events, median nadir CD4 83 cells/μL (range 1-334), median baseline CD4 547 cells/μL (range 136-1652)] were enrolled. Proportion of patients with NCI was low, accounting for 13% at baseline and 16.5% after 1 year (P = 0.687). Memory was the only single domain in which decreased performance after 1 year was observed (-0.25 Z-score, P = 0.025). In patients with significant decrease (≥0.5 SD) in memory performance (n = 20), significantly lower CD14CD16CD163 (% CD14CD16) (P = 0.038) and higher CD14CD38 (% CD14) (P = 0.030) levels were observed.

CONCLUSIONS

In virologically suppressed HIV-infected patients, the evolution of memory performance could be linked to the expression of certain peripheral activated M/M phenotypes. Such associations should be verified in larger populations over the long term.

Increased Natural Killer Cell Activation in HIV-Infected Immunologic Non-Responders Correlates with CD4+ T Cell Recovery after Antiretroviral Therapy and Viral Suppression

The role of natural killer (NK) cell function in HIV disease especially in the setting of long-term antiretroviral therapy (ART) and viral suppression is not fully understood. In the current study, we have investigated NK cell activation in healthy controls and aviremic ART-treated HIV+ subjects with different degrees of immune restoration. We performed a cross sectional study in 12 healthy controls and 24 aviremic ART-treated HIV-infected subjects including 13 HIV+ subjects with CD4+ T cells above 500 cells/μL defined as "immunologic responders" and 11 HIV+ subjects with CD4+ T cells below 350 cells/μL defined as "immunologic non-responders". We analyzed NK cell number, subset, and activation by expression of CD107a and NKG2D and co-expression of CD38 and HLA-DR. NK cell-mediated cytotoxicity against uninfected CD4+ T cells was tested in vitro. We found that NK cell absolute number, percentage of NK cells, and percentage of NK cell subsets were similar in the three study groups. The increased NK cell activation was found predominantly in CD56dimCD16+ subset of immunologic non-responders but not immunologic responders compared to healthy controls. The activation of NK cells was inversely correlated with the peripheral CD4+ T cell count in HIV+ subjects, even after controlling for chronic T cell activation, sex, and age, potential contributors for CD4+ T cell counts in HIV disease. Interestingly, NK cells from immunologic non-responders mediated cytotoxicity against uninfected CD4+ T cells ex vivo. NK cells may play a role in blunted CD4+ T cell recovery in ART-treated HIV disease.