Years Of Suppressive Antiretroviral Therapy Research Articles

HIV immunological non-responders are characterized by extensive immunosenescence and impaired lymphocyte cytokine production capacity.

Immunological non-responders (INR) are people living with HIV (PLHIV) who fail to fully restore CD4+ T-cell counts despite complete viral suppression with antiretroviral therapy (ART). INR are at higher risk for non-HIV related morbidity and mortality. Previous research suggest persistent qualitative defects. The 2000HIV study (clinical trials NTC03994835) enrolled 1895 PLHIV, divided in a discovery and validation cohort. PLHIV with CD4 T-cell count <350 cells/mm3 after ≥2 years of suppressive ART were defined as INR and were compared to immunological responders (IR) with CD4 T-cell count >500 cells/mm3. Logistic and rank based regression were used to analyze clinical data, extensive innate and adaptive immunophenotyping, and ex vivo monocyte and lymphocyte cytokine production after stimulation with various stimuli. The discovery cohort consisted of 62 INR and 1224 IR, the validation cohort of 26 INR and 243 IR. INR were older, had more advanced HIV disease before starting ART and had more frequently a history of non-AIDS related malignancy. INR had lower absolute CD4+ T-cell numbers in all subsets. Activated (HLA-DR+, CD38+) and exhausted (PD1+) subpopulations were proportionally increased in CD4 T-cells. Monocyte and granulocyte immunophenotypes were comparable. INR lymphocytes produced less IL-22, IFN-γ, IL-10 and IL-17 to stimuli. In contrast, monocyte cytokine production did not differ. The proportions of CD4+CD38+HLA-DR+ and CD4+PD1+ subpopulations showed an inversed correlation to lymphocyte cytokine production. INR compared to IR have hyperactivated and exhausted CD4+ T-cells in combination with lymphocyte functional impairment, while innate immune responses were comparable. Our data provide a rationale to consider the use of anti-PD1 therapy in INR.

Predictors of HIV rebound differ by timing of antiretroviral therapy initiation.

BACKGROUNDIdentifying factors that predict the timing of HIV rebound after treatment interruption will be crucial for designing and evaluating interventions for HIV remission.METHODSWe performed a broad evaluation of viral and immune factors that predict viral rebound (AIDS Clinical Trials Group A5345). Participants initiated antiretroviral therapy (ART) during chronic (N = 33) or early (N = 12) HIV infection with ≥ 2 years of suppressive ART and restarted ART if they had 2 viral loads ≥ 1,000 copies/mL after treatment interruption.RESULTSCompared with chronic-treated participants, early-treated individuals had smaller and fewer transcriptionally active HIV reservoirs. A higher percentage of HIV Gag-specific CD8+ T cell cytotoxic response was associated with lower intact proviral DNA. Predictors of HIV rebound timing differed between early- versus chronic-treated participants, as the strongest reservoir predictor of time to HIV rebound was level of residual viremia in early-treated participants and intact DNA level in chronic-treated individuals. We also identified distinct sets of pre-treatment interruption viral, immune, and inflammatory markers that differentiated participants who had rapid versus slow rebound.CONCLUSIONThe results provide an in-depth overview of the complex interplay of viral, immunologic, and inflammatory predictors of viral rebound and demonstrate that the timing of ART initiation modifies the features of rapid and slow viral rebound.TRIAL REGISTRATIONClinicalTrials.gov NCT03001128FUNDINGNIH National Institute of Allergy and Infectious Diseases, Merck.

Increased Levels of Caspase-1 and IL-1β Among Adults With Persistent Immune Activation After 12 Years of Suppressive Antiretroviral Therapy in the Infectious Diseases Institute HIV Treatment Cohort.

We sought evidence of activated pyroptosis and the inflammasome pathways among human immunodeficiency virus (HIV)-infected adults after 12 years of suppressive antiretroviral therapy (ART) and persistent immune activation in the Infectious Diseases Institute HIV treatment cohort in Uganda. In a cross-sectional study, using peripheral blood mononuclear cells of HIV-infected individuals with high and low immune activation (CD4/CD8+CD38+HLA-DR+ cells) relative to HIV-negative reference group, caspase-1 expression was measured using flow cytometry and plasma interleukin 18 and interleukin 1β (IL-1β) levels using enzyme-linked immunosorbent assay. There was higher expression of caspase-1 by CD4 T cells of ART-treated individuals with high immune activation relative to those with lower immune activation (P = .04). Similarly, plasma levels of IL-1β were higher among ART-treated individuals with high immune activation levels relative to those with low immune activation levels (P = .009). We observed a low positive correlation between caspase-1 expression by CD4/CD8 T cells and immune activation levels (r= 0.497 and r= 0.329, respectively). Caspase-1 and IL-1β were high among individuals with high immune activation despite 12 years of suppressive ART. There is a need to further understand the role of persistent abortive infection and the latent HIV reservoir characteristics as drivers of persistent activation and inflammation and to subsequently intervene to prevent the complications of chronic immune activation during long-term ART.

No evidence that circulating HIV-specific immune responses contribute to persistent inflammation and immune activation in persons on long-term ART.

People with HIV (PWH) have persistently elevated levels of inflammation and immune activation despite suppressive antiretroviral therapy (ART), with specific biomarkers showing associations with non-AIDS-defining morbidities and mortality. We investigated the potential role of the HIV-specific adaptive immune response, which also persists under ART, in driving levels of these clinically relevant biomarkers. Cohort-based study. HIV-specific IFN-γ-producing T-cell responses and antibody concentrations were measured in blood at study entry in the ACTG A5321 cohort, following a median of 7 years of suppressive ART. HIV persistence measures including cell-associated (CA)-DNA, CA-RNA, and plasma HIV RNA (single-copy assay) were also assessed at study entry. Plasma inflammatory biomarkers and T-cell activation and cycling were measured at a pre-ART time point and at study entry. Neither the magnitudes of HIV-specific T-cell responses nor HIV antibody levels were correlated with levels of the inflammatory or immune activation biomarkers, including hs-CRP, IL-6, neopterin, sCD14, sCD163, TNF-α, %CD38 + HLA-DR + CD8 + and CD4 + cells, and %Ki67 + CD8 + and CD4 + cells - including after adjustment for pre-ART biomarker level. Plasma HIV RNA levels were modestly correlated with CD8 + T-cell activation ( r = 0.25, P = 0.027), but other HIV persistence parameters were not associated with these biomarkers. In mediation analysis, relationships between HIV persistence parameters and inflammatory biomarkers were not influenced by either HIV-specific T-cell responses or antibody levels. Adaptive HIV-specific immune responses do not appear to contribute to the elevated inflammatory and immune activation profile in persons on long-term ART.

Immunological Correlates of the HIV-1 Replication-Competent Reservoir Size.

Understanding what shapes the latent human immunodeficiency virus type 1 (HIV-1) reservoir is critical for developing strategies for cure. We measured frequency of persistent HIV-1 infection after 5 years of suppressive antiretroviral therapy initiated during chronic infection. Pretreatment CD8+ T-cell activation, nadir CD4 count, and CD4:CD8 ratio predicted reservoir size.

IFNL4 Genotype Does Not Associate with CD4 T-Cell Recovery in People Living with Human Immunodeficiency Virus.

Immune non-responders (INRs) are people with HIV infection who fail to restore their CD4 T-cell counts in spite of prolonged virologic suppression, a condition associated with higher rates of all-cause mortality. The mechanisms of immune non-response are not entirely clear. We used existing clinical and genetic data from AIDS Clinical Trials Group clinical trials to ask whether an IFNL4 single-nucleotide polymorphism, shown to be associated with outcomes for other infectious diseases, correlated with immune non-response for HIV. Analysis of data from 426 participants with clearly defined CD4 T-cell recovery phenotypes, including 88 INRs with CD4 < 200 cells/mm3 after 2 years of suppressive antiretroviral therapy, did not identify an association of IFNL4 genotype with immune non-response. Thus, the IFNL4 genotype is unlikely to influence immunologic recovery.

Measuring the Success of HIV-1 Cure Strategies.

HIV-1 eradication strategies aim to achieve viral remission in the absence of antiretroviral therapy (ART). The development of an HIV-1 cure remains challenging due to the latent reservoir (LR): long-lived CD4 T cells that harbor transcriptionally silent HIV-1 provirus. The LR is stable despite years of suppressive ART and is the source of rebound viremia following therapy interruption. Cure strategies such as “shock and kill” aim to eliminate or reduce the LR by reversing latency, exposing the infected cells to clearance via the immune response or the viral cytopathic effect. Alternative strategies include therapeutic vaccination, which aims to prime the immune response to facilitate control of the virus in the absence of ART. Despite promising advances, these strategies have been unable to significantly reduce the LR or increase the time to viral rebound but have provided invaluable insight in the field of HIV-1 eradication. The development and assessment of an HIV-1 cure requires robust assays that can measure the LR with sufficient sensitivity to detect changes that may occur following treatment. The viral outgrowth assay (VOA) is considered the gold standard method for LR quantification due to its ability to distinguish intact and defective provirus. However, the VOA is time consuming and resource intensive, therefore several alternative assays have been developed to bridge the gap between practicality and accuracy. Whilst a cure for HIV-1 infection remains elusive, recent advances in our understanding of the LR and methods for its eradication have offered renewed hope regarding achieving ART free viral remission.

Clones of infected cells arise early in HIV-infected individuals.

In HIV-infected individuals on long-term antiretroviral therapy (ART), more than 40% of the infected cells are in clones. Although most HIV proviruses present in individuals on long-term ART are defective, including those in clonally expanded cells, there is increasing evidence that clones carrying replication-competent proviruses are common in patients on long-term ART and form part of the HIV reservoir that makes it impossible to cure HIV infection with current ART alone. Given the importance of clonal expansion in HIV persistence, we determined how soon after HIV acquisition infected clones can grow large enough to be detected (clones larger than ca. 1 × 105 cells). We studied 12 individuals sampled in early HIV infection (Fiebig stage III-V/VI) and 5 who were chronically infected. The recently infected individuals were started on ART at or near the time of diagnosis. We isolated more than 6,500 independent integration sites from peripheral blood mononuclear cells before ART was initiated and after 0.5-18 years of suppressive ART. Some infected clones could be detected approximately 4 weeks after HIV infection and some of these clones persisted for years. The results help to explain how the reservoir is established early and persists for years.

Human Immunodeficiency Virus Type 1 RNA Detected in the Central Nervous System (CNS) After Years of Suppressive Antiretroviral Therapy Can Originate from a Replicating CNS Reservoir or Clonally Expanded Cells.

Human immunodeficiency virus type 1 (HIV-1) populations are detected in cerebrospinal fluid (CSF) of some people on suppressive antiretroviral therapy (ART). Detailed analysis of these populations may reveal whether they are produced by central nervous system (CNS) reservoirs. We performed a study of 101 asymptomatic participants on stable ART. HIV-1 RNA concentrations were cross-sectionally measured in CSF and plasma. In participants with CSF HIV-1 RNA concentrations sufficient for analysis, viral populations were genetically and phenotypically characterized over multiple time points. For 6% of participants (6 of 101), the concentration of HIV-1 RNA in their CSF was ≥0.5 log copies/mL above that of plasma (ie, CSF escape). We generated viral envelope sequences from CSF of 3 participants. One had a persistent CSF escape population that was macrophage-tropic, partially drug resistant, genetically diverse, and closely related to a minor macrophage-tropic lineage present in the blood prior to viral suppression and enriched for after ART. Two participants (1 suppressed and 1 not) had transient CSF escape populations that were R5 T cell-tropic with little genetic diversity. Extensive analysis of viral populations in 1 participant revealed that CSF escape was from a persistently replicating population, likely in macrophages/microglia, present in the CNS over 3 years of ART. CSF escape in 2 other participants was likely produced by trafficking and transient expansion of infected T cells in the CNS. Our results show that CNS reservoirs can persist during ART and that CSF escape is not exclusively produced by replicating CNS reservoirs.

Persistent central nervous system immune activation following more than 10 years of effective HIV antiretroviral treatment

Low-grade immune activation is common in people living with HIV (PLHIV), despite long-term viral suppression by antiretroviral therapy (ART). The clinical significance of this activation remains unclear. The aim of this study was to examine residual intrathecal immune activation in relation to signs of neuronal injury and neurocognitive impairment in PLHIV who had been virally suppressed on ART for more than 10 years. Twenty neuroasymptomatic PLHIV on suppressive ART for a median of 13.2 years were retrospectively identified from the longitudinal prospective Gothenburg HIV cerebrospinal fluid (CSF) study. HIV-RNA, neopterin, and neurofilament light protein (NFL) levels were measured in paired plasma and CSF samples. Pretreatment samples were available for 14 patients. Cognitive function was assessed by CogState at follow-up. CSF neopterin decreased from a median (IQR) of 17.8 (10.6-29.7) to 6.1 (4.6-8.0) nmol/l during treatment (P < 0.001). In 11 out of 20 participants (55%), CSF neopterin levels were above the upper normal reference limit (5.8 nmol/l) at follow-up. Age-adjusted CSF NFL decreased to within-normal levels from a median of (IQR) 1179 (557-2707) to 415 (292-610) ng/l (P < 0.001). No significant correlations were found between CSF neopterin and CSF NFL or neurocognitive performance. Although CSF neopterin decreased significantly, more than 50% of the patients had CSF concentrations above the upper normal reference value despite more than 10 years of suppressive ART. We found no correlation between CSF neopterin, CSF NFL or neurocognitive performance at follow-up, indicating that low-grade immune activation during suppressive ART may be clinically benign.

Anti-Human Immunodeficiency Virus Antibodies in the Cerebrospinal Fluid: Evidence of Early Treatment Impact on Central Nervous System Reservoir?

Despite effective antiretroviral therapy (ART), human immunodeficiency virus (HIV) likely persists in the central nervous system (CNS) in treated individuals. We examined anti-HIV antibodies in cerebrospinal fluid (CSF) and blood as markers of persistence. Human immunodeficiency virus antibodies were measured in paired CSF and serum before and after long-term treatment of chronic (n = 10) and early infection (n = 12), along with untreated early infection (n = 10). Treatment of chronic infection resulted in small reductions of anti-HIV antibodies in CSF and serum despite >10 years of suppressive ART. In untreated early infection, anti-HIV antibodies emerged in blood by day 30, whereas CSF antibodies reached similar levels 2 weeks later. Compared with long-term treatment of chronic infection, early ART initiation reduced CSF antibodies by 43-fold (P > .0001) and blood antibodies by 7-fold (P = .0003). Two individuals receiving pre-exposure prophylaxis and then ART early after infection failed to develop antibodies in CSF or blood, whereas CSF antibodies were markedly reduced in the Berlin patient. To the extent that differential CSF and blood antibodies indicate HIV persistence, these data suggest a relative delay in establishment of the CNS compared with the systemic HIV reservoir that provides an opportunity for early treatment to have a greater impact on the magnitude of long-term CNS infection.

Do T cells from HIV-infected individuals have normal metabolic function?

Abstract Untreated HIV infection is characterized by generalized immune activation, T cell dysfunction, and ultimately the exhaustion of HIV-specific CD8 T cell responses. Durable virus suppression resulting from anti-retroviral therapy (ART) is associated with greatly improved immune function, but some phenotypic and functional abnormalities persist even after years of suppressive ART. We have observed that, relative to HIV-seronegative individuals, CD8 T cells from HIV+ participants on ART are skewed toward a more effector-like (T-bethigh Eomeslow) phenotype and have significantly reduced proliferative capacity in response to antigenic stimulation. Metabolic pathways play a key role in shaping T cell maturation, phenotype, and function, and the ability to produce ATP via both glycolytic and oxidative phosphorylation (mitochondrial) pathways is critical to T cell function and longevity. However, whether underlying metabolic abnormalities contribute to residual CD8 T cell dysfunction in HIV+ individuals on ART has not been fully explored. Here we compare the metabolic phenotype of T cells from HIV+ participants on ART with those from HIV-seronegative participants. We are using MitoTracker® dyes to assess mitochondrial mass and polarization in T cell memory subsets, ex vivo and in response to antigen, and measuring expression of the glucose transporter GLUT1 and the mitochondrial biogenesis master regulator PGC-1α in different CD8 T cell effector subsets. Our findings will inform whether phenotypic and functional abnormalities in CD8 T cells from HIV+ individuals on ART reflect underlying metabolic dysfunction and if metabolic interventions could improve T cell function.

Proviruses with identical sequences comprise a large fraction of the replication-competent HIV reservoir.

The major obstacle to curing HIV infection is the persistence of cells with intact proviruses that can produce replication-competent virus. This HIV reservoir is believed to exist primarily in CD4+ T-cells and is stable despite years of suppressive antiretroviral therapy. A potential mechanism for HIV persistence is clonal expansion of infected cells, but how often such clones carry replication-competent proviruses has been controversial. Here, we used single-genome sequencing to probe for identical HIV sequence matches among viruses recovered in different viral outgrowth cultures and between the sequences of outgrowth viruses and proviral or intracellular HIV RNA sequences in uncultured blood mononuclear cells from eight donors on suppressive ART with diverse proviral populations. All eight donors had viral outgrowth virus that was fully susceptible to their current ART drug regimen. Six of eight donors studied had identical near full-length HIV RNA sequences recovered from different viral outgrowth cultures, and one of the two remaining donors had identical partial viral sequence matches between outgrowth virus and intracellular HIV RNA. These findings provide evidence that clonal expansion of HIV-infected cells is an important mechanism of reservoir persistence that should be targeted to cure HIV infection.

Establishment and stability of the latent HIV-1 DNA reservoir.

HIV-1 infection cannot be cured because the virus persists as integrated proviral DNA in long-lived cells despite years of suppressive antiretroviral therapy (ART). In a previous paper (Zanini et al, 2015) we documented HIV-1 evolution in 10 untreated patients. Here we characterize establishment, turnover, and evolution of viral DNA reservoirs in the same patients after 3-18 years of suppressive ART. A median of 14% (range 0-42%) of the DNA sequences were defective due to G-to-A hypermutation. Remaining DNA sequences showed no evidence of evolution over years of suppressive ART. Most sequences from the DNA reservoirs were very similar to viruses actively replicating in plasma (RNA sequences) shortly before start of ART. The results do not support persistent HIV-1 replication as a mechanism to maintain the HIV-1 reservoir during suppressive therapy. Rather, the data indicate that DNA variants are turning over as long as patients are untreated and that suppressive ART halts this turnover.

PD-1(+) and follicular helper T cells are responsible for persistent HIV-1 transcription in treated aviremic individuals.

The mechanisms responsible for the persistence of HIV-1 after many years of suppressive antiretroviral therapy (ART) have been only partially elucidated. Most of the studies investigating HIV-1 persistence have been performed with blood, although it is well known that germinal centers (GCs) within lymph nodes (LNs) serve as primary sites for HIV-1 replication. We sought to identify the memory CD4 T cell populations in blood and LNs that are responsible for the production of replication-competent and infectious HIV-1, as well as for active and persistent virus transcription in ART-treated (for 1.5-14.0 years), aviremic (<50 HIV RNA copies/ml) HIV-infected individuals. We demonstrate that LN CD4 T cells that express programmed cell death 1 (PDCD1; also known as PD-1), which are composed of about 65% T follicular helper cells as defined by the expression of the cell surface receptors CXCR5 and PD-1, are the major source of replication-competent HIV-1 and of infectious virus, as compared to any other (CXCR5(-)PD-1(-) and CXCR5(+)PD-1(-)) blood or LN memory CD4 T cell populations. LN PD-1(+) cells accounted for 46% and 96% of the total pools of memory CD4 T cells containing inducible replication-competent or infectious virus, respectively. Notably, higher levels of cell-associated HIV-1 RNA were present in LN PD-1(+) cells after long-term (up to 12 years) ART than in other memory CD4 T cell subpopulations. These results indicate that LN PD-1(+) cells are the major CD4 T cell compartment in the blood and LNs for the production of replication-competent and infectious HIV-1, and for active and persistent virus transcription in long-term-ART-treated aviremic individuals. Thus, these cells may represent a major obstacle to finding a functional cure for HIV-1 infection.

How Much HIV is Alive? The Challenge of Measuring Replication Competent HIV for HIV Cure Research

How Much HIV is Alive? The Challenge of Measuring Replication Competent HIV for HIV Cure Research

During Stably Suppressive Antiretroviral Therapy Integrated HIV-1 DNA Load in Peripheral Blood is Associated with the Frequency of CD8 Cells Expressing HLA-DR/DP/DQ

BackgroundCharacterising the correlates of HIV persistence improves understanding of disease pathogenesis and guides the design of curative strategies. This study investigated factors associated with integrated HIV-1 DNA load during consistently suppressive first-line antiretroviral therapy (ART). MethodTotal, integrated, and 2-long terminal repeats (LTR) circular HIV-1 DNA, residual plasma HIV-1 RNA, T-cell activation markers, and soluble CD14 (sCD14) were measured in peripheral blood of 50 patients that had received 1–14years of efavirenz-based or nevirapine-based therapy. ResultsIntegrated HIV-1 DNA load (per 106 peripheral blood mononuclear cells) was median 1.9 log10 copies (interquartile range 1.7–2.2) and showed a mean difference of 0.2 log10 copies per 10years of suppressive ART (95% confidence interval −0.2, 0.6; p=0.28). It was positively correlated with total HIV-1 DNA load and frequency of CD8+HLA-DR/DP/DQ+ cells, and was also higher in subjects with higher sCD14 levels, but showed no correlation with levels of 2-LTR circular HIV-1 DNA and residual plasma HIV-1 RNA, or the frequency of CD4+CD38+ and CD8+CD38+ cells. Adjusting for pre-ART viral load, duration of suppressive ART, CD4 cell counts, residual plasma HIV-1 RNA levels, and sCD14 levels, integrated HIV-1 DNA load was mean 0.5 log10 copies higher for each 50% higher frequency of CD8+HLA-DR/DP/DQ+ cells (95% confidence interval 0.2, 0.9; p=0.01). ConclusionsThe observed positive association between integrated HIV-1 DNA load and frequency of CD8+DR/DP/DQ+ cells indicates that a close correlation between HIV persistence and immune activation continues during consistently suppressive therapy. The inducers of the distinct activation profile warrant further investigation.

Low antigen-specific CD4 T-cell immune responses despite normal absolute CD4 counts after long-term antiretroviral therapy an African cohort

BackgroundCD4 counts guide antiretroviral therapy (ART) initiation and prophylaxis for opportunistic infections. It is unclear whether normal CD4 counts translate to normalized immune responses among ART-treated adults. We compared antigen-specific CD4 T-cell immune responses among ART-treated adults with CD4≥500cells/μl, optimal immune responders (O-IR), and their age-matched healthy HIV-negative counterparts. MethodsIn a sample-based case–control study, cryopreserved peripheral blood mononuclear cells from 15 O-IR after 7 years of ART and 15 healthy controls, were analyzed for CD4+ T-cell proliferation using CFSE dye and cytokine production. ResultsCD4 T-cell proliferation, upon stimulation with PPD and pneumococcal polysaccharide antigen, was lower among O-IR relative to HIV-negative controls; p=0.016 and p=0.016 respectively. CD4 T-cell production of IL-2 was lower among O-IR relative to HIV-negative control p=0.002. CD4 T-cell proliferation upon stimulation with SEB and CMV antigens was similar among O-IR and HIV-negative controls p=0.971 and p=0.480, respectively, and so was IL-4 and IFN γ production; p=0.528 and p=0.892, respectively. ConclusionSeven years of suppressive ART caused partial CD4 T-cell function recovery in an African HIV treatment cohort, despite restoration of CD4 T-cell counts to levels≥500cells/μl. The role innate immunity in the recovery of immune function during long-term ART should be investigated to guide decisions on continued prophylaxis against opportunistic infections.

Discordance Between Peripheral and Colonic Markers of Inflammation During Suppressive ART

Persistent systemic inflammation is associated with the inability of some HIV-infected patients to normalize circulating CD4 T-cell levels after years of suppressive antiretroviral therapy. In this study, we sought to understand whether such systemic inflammation is also associated with detectable signs of inflammation in biopsies from the rectosigmoid colon. Immunologic and virological parameters were studied in the peripheral blood and in rectosigmoid colon biopsies from individuals with viral suppression for at least 2 years and with peripheral CD4 T-cell levels of <350 cells per cubic millimeter (immunologic nonresponders, n = 18) or >500 cells per cubic millimeter (immunologic responders, n = 16). Peripheral blood and rectosigmoid colon biopsies were analyzed by flow cytometry, enzyme-linked immunosorbent assay, and quantitative polymerase chain reaction. Nonresponders had elevated T-cell activation and inflammatory cytokines in the circulation, but inflammatory gene expression in colon biopsies was not different as compared with responders, and there was little relationship between blood and colon markers of inflammation. Blood inflammatory markers were positively associated with soluble CD14 levels indicative of monocyte activation. These findings demonstrate that, in the context of treated HIV disease, it is easier to detect parameters of inflammation (including blood monocyte activation) in the peripheral blood than in isolated rectosigmoid colon biopsies. Accordingly, interventions to block such inflammation in this population might be most conveniently and accurately assessed in blood.

High CD56++CD16- natural killer (NK) cells among suboptimal immune responders after four years of suppressive antiretroviral therapy in an African adult HIV treatment cohort

BackgroundUp to 40% of HIV-infected individuals receiving Highly Active Antiretroviral Therapy (HAART) have poor CD4+ T-cell recovery. The role of natural killer (NK) cells in immune recovery during HAART is not well understood. We described the profiles of NK cell subsets and their expression of activating receptor, NKG2D and cytotoxicity receptor NKp46 among suboptimal immune responders to despite four years of suppressive HAART.MethodsA case control study utilized frozen peripheral blood mononuclear cells (PBMC) from a cohort of HIV-infected adults that initiated HAART in 2004/5, at CD4 < 200 cells/μl. Cases were ‘suboptimal’ responders; patients within the lowest quartile of CD4+ T-cell reconstitution, with a median CD4 count increase of 129 (-43-199) cells/μl (difference between CD4 count at baseline and after 4 years of HAART) and controls were ‘super-optimal’ responders; patients within the highest quartile of CD4 T-cell reconstitution with a median CD4 count increase of 528 (416-878) cells/μl). Expression of NK cell lineage markers (CD56+/-CD16+/-) and receptors NKG2D and NKp46, was measured among PBMC from 29 cases of ‘suboptimal’ responders’ and 23 controls of ‘super-optimal responders’, and compared among ‘suboptimal’ and ‘super-optimal’ responders. NK cell populations were compared using the Holm Sidak multiple comparison test and p values < 0.05 were considered statistically significant. Data was analyzed using FLOWJO and GraphPad Prism 6.Results‘Suboptimal responders’ had a higher proportion of cytokine producing CD56++CD16+/- (CD56bri) NK cells than the ‘super-optimal responders’ p = 0.017, and CD56neg NK cells were lower among suboptimal than super-optimal responders (p = 0.007). The largest NK cell subset, CD56dim, was comparable among suboptimal responders and ‘super-optimal immune responders’. Expression of NKG2D and NKp46 receptors on NK cell subsets (CD56bri, CD56neg and CD56dim), was comparable among ‘suboptimal’ and ‘super-optimal’ immune responders.ConclusionsThe pro-inflammatory CD56++CD16-- NK cells were higher among ‘suboptimal’ responders relative to ‘super-optimal’ responders, despite four years of suppressive HAART. Alteration of NK cell populations could inhibit host immune responses to infections among suboptimal responders. We recommend further analysis of NK cell function among suboptimal immune responders in order to inform targeted interventions to optimize immune recovery among HAART-treated adults.