Exhaustion of Activated CD8 T Cells Predicts Disease Progression in Primary HIV-1 Infection

Persistent metabolic changes in HIV-infected patients during the first year of combination antiretroviral therapy

The HIV-human metabolic relationship is a complex interaction convoluted even more by antiretroviral therapy (cART) and comorbidities. The ability of cART to undo the HIV induced metabolic dysregulation is unclear and under-investigated. Using targeted metabolomics and multiplex immune biomarker analysis, we characterized plasma samples obtained from 18 untreated HIV-1-infected adult patients and compared these to a non-HIV infected (n = 23) control population. The biogenic amine perturbations during an untreated HIV infection implicated altered tryptophan- nitrogen- and muscle metabolism. Furthermore, the lipid profiles of untreated patients were also significantly altered compared to controls. In untreated HIV infection, the sphingomyelins and phospholipids correlated negatively to markers of infection IP-10 and sIL-2R whereas a strong association was found between triglycerides and MCP-1. In a second cohort, we characterized plasma samples obtained from 28 HIV-1-infected adult patients before and 12 months after the start of cART, to investigate the immune-metabolic changes associated with cART. The identified altered immune-metabolic pathways of an untreated HIV infection showed minimal change after 12 months of cART. In conclusion, 12 months of cART impacts only mildly on the metabolic dysregulation underlying an untreated HIV infection and provide insights into the comorbidities present in virally suppressed HIV patients.

A Low Frequency of IL-17-Producing CD8+ T-Cells Is Associated With Persistent Immune Activation in People Living With HIV Despite HAART-Induced Viral Suppression

Immune activation is the hallmark of HIV infection, even in patients with highly active anti-retroviral therapy (HAART)-induced viral suppression. A major cause of immune activation during HIV infection is the intestinal microbial translocation as a consequence, among other factors, of the decrease and/or dysfunction of interleukin (IL)-17-producing T-cells, due to their role promoting the integrity of the intestinal barrier. A population of IL-17-producing CD8⁺ T-cells (Tc17 cells), characterized by the expression of CD161, has been described, but its relation with the persistent immune activation in non-viremic people living with HIV (PLWH) on HAART is unclear. By flow cytometry, we characterized the activation phenotype (evaluated by the expression of HLA-DR and CD38) of circulating CD161-expressing CD8⁺ T-cells; in addition, we explored the functionality of polyclonally-stimulated Tc17 cells in PLWH under HAART-induced viral suppression, and in healthy individuals. Finally, we determined the association of Tc17 cells with the expression of cellular and soluble activation markers. Circulating CD161-expressing CD8⁺ T-cells were decreased in PLWH compared with healthy individuals, despite their similar basal activation state. After polyclonal stimulation, IL-17 production was higher in CD8⁺ T-cells co-expressing HLA-DR and CD38 in healthy individuals. In contrast, although PLWH had a higher frequency of HLA-DR⁺ CD38⁺ CD8⁺ T-cells after stimulation, they had a lower production of IL-17. Interferon (IFN)-γ-producing CD8⁺ T-cells (Tc1 cells) were increased in PLWH. The low Tc17 cells response was associated with a high expression of CD38 and programmed death 1 protein, high levels of soluble CD14 and the treatment duration. Finally, to explore potential immunomodulatory strategies, the in vitro effect of the anti-inflammatory agent sulfasalazine was assessed on Tc17 cells. Interestingly, a decreased inflammatory environment, death of activated CD8⁺ T-cells, and an increased frequency of Tc17 cells were observed with sulfasalazine treatment. Thus, our findings suggest that activated CD8⁺ T-cells have a marked capacity to produce IL-17 in healthy individuals, but not in PLWH, despite HAART. This dysfunction of Tc17 cells is associated with the persistent immune activation observed in these patients, and can be partially restored by anti-inflammatory agents.

Immune Protection of SIV Challenge by PD-1 Blockade During Vaccination in Rhesus Monkeys

Though immune correlates for protection are still under investigation, potent cytotoxic T lymphocyte responses are desirable for an ideal HIV-1 vaccine. PD-1 blockade enhances SIV-specific CD8+ T cells. However, little information has been reported about how it affects the immunogenicity and protection of prophylactic SIV vaccines in nonhuman primates. Here, we show that PD-1 blockade during vaccination substantially improved protective efficacy in SIV challenged macaques. The PD-1 pathway was blocked using a monoclonal antibody specific to human PD-1. Administration of this antibody effectively augmented and sustained vaccine-induced SIV-specific T cell responses for more than 42 weeks after first immunization in rhesus monkeys, as compared with SIV vaccination only. Importantly, after intrarectally repeated low-dosage challenge with highly pathogenic SIVmac239, monkeys with PD-1 blockade during vaccination achieved full protection against incremental viral doses of up to 50,000 TICD₅₀. These findings highlight the importance of PD-1 blockade during vaccination for the development of HIV vaccines.

IL-17 and IL-22 production in HIV+ individuals with latent and active tuberculosis

BACKGROUND

IL-17 and IL-22 cytokines play an important role in protective immune responses against Mycobacterium tuberculosis (Mtb) infection. Information on the production of these cytokines and the factors that regulate their production in the context of human immunodeficiency virus (HIV) and latent tuberculosis infection (LTBI) or active tuberculosis disease (ATB) is limited. In the current study, we compared the production of these two cytokines by PBMC of HIV-LTBI+ and HIV + LTBI+ individuals in response to Mtb antigens CFP-10 (culture filtrate protein) and ESAT-6 (Early Secretory Antigenic Target). We also determined the mechanisms involved in their production.

METHODS

We cultured Peripheral Blood Mononuclear Cells (PBMCs) from HIV- individuals and HIV+ patients with latent tuberculosis and active disease with CFP-10 and ESAT-6. Production of IL-17, IL-22 and PD1 (Programmed Death 1), ICOS (Inducible T-cell Costimulator), IL-23R and FoxP3 (Forkhead box P3) expression on CD4+ T cells was measured.

RESULTS

In response to Mtb antigens CFP-10 and ESAT-6, freshly isolated PBMCs from HIV+ LTBI+ and HIV+ active TB patients produced less IL-17 and IL-22 and more IL-10, expressed less IL-23R, and more PD1 and expanded to more FoxP3+ cells. Active TB infection in HIV+ individuals further inhibited antigen specific IL-17 and IL-22 production compared to those with LTBI. Neutralization of PD1 restored IL-23R expression, IL-17 and IL-22 levels and lowered IL-10 production and reduced expansion of FoxP3 T cells.

CONCLUSIONS

In the current study we found that increased PD1 expression in HIV + LTBI+ and HIV+ active TB patients inhibits IL-17, IL-22 production and IL-23R expression in response to Mtb antigens CFP-10 and ESAT-6.

CD32-Expressing CD4 T Cells Are Phenotypically Diverse and Can Contain Proviral HIV DNA

Efforts to both characterize and eradicate the HIV reservoir have been limited by the rarity of latently infected cells and the absence of a specific denoting biomarker. CD32a (FcγRIIa) has been proposed to be a marker for an enriched CD4 T cell HIV reservoir, but this finding remains controversial. Here, we explore the expression of CD32 on CD3⁺CD4⁺ cells in participants from two primary HIV infection studies and identify at least three distinct phenotypes (CD32^low, CD32⁺CD14⁺, and CD32^high). Of note, CD4 negative enrichment kits remove the majority of CD4⁺CD32⁺ T cells, potentially skewing subsequent analyses if used. CD32^high CD4 T cells had higher levels of HLA-DR and HIV co-receptor expression than other subsets, compatible with their being more susceptible to infection. Surprisingly, they also expressed high levels of CD20, TCRαβ, IgD, and IgM (but not IgG), markers for both T cells and naïve B cells. Compared with other populations, CD32^low cells had a more differentiated memory phenotype and high levels of immune checkpoint receptors, programmed death receptor-1 (PD-1), Tim-3, and TIGIT. Within all three CD3⁺CD4⁺CD32⁺ phenotypes, cells could be identified in infected participants, which contained HIV DNA. CD32 expression on CD4 T cells did not correlate with HIV DNA or cell-associated HIV RNA (both surrogate measures of overall reservoir size) or predict time to rebound viremia following treatment interruption, suggesting that it is not a dominant biomarker for HIV persistence. Our data suggest that while CD32⁺ T cells can be infected with HIV, CD32 is not a specific marker of the reservoir although it might identify a population of HIV enriched cells in certain situations.

The function and dysfunction of memory CD8+ T cells in tumor immunity

The generation and maintenance of CD8+ T cell memory is crucial to long-term host survival, yet the basic tenets of CD8+ T cell immunity are still being established. Recent work has led to the discovery of tissue-resident memory cells and refined our understanding of the transcriptional and epigenetic basis of CD8+ T cell differentiation and dysregulation. In parallel, the unprecedented clinical success of immunotherapy has galvanized an intense, global research effort to decipher and de-repress the anti-tumor response. However, the progress of immunotherapy is at a critical juncture, since the efficacy of immuno-oncology agents remains confined to a fraction of patients and often fails to provide durable benefit. Unlocking the potential of immunotherapy requires the design of strategies that both induce a potent effector response and reliably forge stable, functional memory T cell pools capable of protecting from recurrence or relapse. It is therefore essential that basic and emerging concepts of memory T cell biology are rapidly and faithfully transposed to advance therapeutic development in cancer immunotherapy. This review highlights seminal and recent reports in CD8+ T cell memory and tumor immunology, and evaluates recent data from solid cancer specimens in the context of the key paradigms from preclinical models. We elucidate the potential significance of circulating effector cells poised downstream of neoantigen recognition and upstream of T cell dysfunction and propose that cells in this immunological 'sweet spot' may be key anti-tumor effectors.

The Use of the Humanized Mouse Model in Gene Therapy and Immunotherapy for HIV and Cancer

HIV and cancer remain prevailing sources of morbidity and mortality worldwide. There are current efforts to discover novel therapeutic strategies for the treatment or cure of these diseases. Humanized mouse models provide the investigative tool to study the interaction between HIV or cancer and the human immune system in vivo. These humanized models consist of immunodeficient mice transplanted with human cells, tissues, or hematopoietic stem cells that result in reconstitution with a nearly full human immune system. In this review, we discuss preclinical studies evaluating therapeutic approaches in stem cell-based gene therapy and T cell-based immunotherapies for HIV and cancer using a humanized mouse model and some recent advances in using checkpoint inhibitors to improve antiviral or antitumor responses.

Blockage of Core Fucosylation Reduces Cell-Surface Expression of PD-1 and Promotes Anti-tumor Immune Responses of T Cells

Programmed cell death 1 (PD-1) is highly expressed on exhausted T cells and inhibits T cell activation. Antibodies that block the interaction between PD-1 and its ligand prevent this inhibitory signal and reverse T cell dysfunction, providing beneficial anti-tumor responses in a substantial number of patients. Mechanisms for the induction and maintenance of high PD-1 expression on exhausted T cells have not been fully understood. Utilizing a genome-wide loss-of-function screening method based on the CRISPR-Cas9 system, we identified genes involved in the core fucosylation pathway as positive regulators of cell-surface PD-1 expression. Inhibition of Fut8, a core fucosyltransferase, by genetic ablation or pharmacologic inhibition reduced cell-surface expression of PD-1 and enhanced T cell activation, leading to more efficient tumor eradication. Taken together, our findings suggest that blocking core fucosylation of PD-1 can be a promising strategy for improving anti-tumor immune responses.

Elevated Level of CD4+ T Cell Immune Activation in Acutely HIV-1-Infected Stage Associates With Increased IL-2 Production and Cycling Expression, and Subsequent CD4+ T Cell Preservation

Persistent immune activation is a striking consequence of HIV-1 infection and a driving force of CD4⁺ T cell depletion and AIDS events during chronic infection. High level of T cell immune activation associates with antiretroviral therapy (ART)-treated clinical outcomes in chronically HIV-1-infected patients. However, the role of T cell activation during acute infection stage in subsequent CD4⁺ T cell decline in the absence of ART treatment is unknown. In this study, we enrolled 26 acutely HIV-1-infected patients in the absence of ART treatment from a prospective acute HIV-1 infection cohort in Beijing (PRIMO). A comprehensive analysis of CD4⁺ and CD8⁺ T cell immune activation during acute infection stage and the clinical outcomes was studied. We found that patients with higher level of CD4⁺ T cell activation (%CD38⁺HLA-DR⁺CD4⁺ T cells) exhibited more effective function (%IL-2 production and %ki67 expression) in CD4⁺ T cells compared to those from patients without increased T cell activation at the acute phase. Direct correlations were observed between CD4⁺ T cell activation and the percentages of IL-2-producing or ki67-expressing CD4⁺ T cells in patients at the acute phase of infection. Importantly, the increased levels of CD4⁺ T cell immune activation, IL-2 production, and cycling expression during acute infection were associated with less decline of CD4⁺ T cell after 2 years of infection. However, immune exhaustion molecules in acute infection, including CD160, T cell immunoglobulin and ITIM domain, programmed cell death protein 1, and T cell immunoglobulin and mucin 3, were not associated with the CD4⁺ T cell depletion. These significant associations of CD4⁺ T cell activation were not demonstrable for CD8⁺ T cell activation at the acute phase. Taken together, our observations provide new insight into the possible role of T cell activation in preventing CD4⁺ T cell depletion during acute HIV-1 infection.

Expression of PD-1 and Tim-3 markers of T-cell exhaustion is associated with CD4 dynamics during the course of untreated and treated HIV infection

Introduction

T-cell exhaustion has been involved in the pathogenesis of HIV infection. We have longitudinally analyzed PD1 and Tim3 surrogate markers of T-cells exhaustion, in parallel with other markers of HIV progression, and its potential association with CD4 changes in treated and untreated infection.

Patients and methods

96 HIV patients, 49 of them followed in the absence of cART (cART-naïve group) and 47 after initiation of cART (cART group) were included and followed for a median of 43 [IQR: 31–60] months. PD1 and Tim3 expression, CD8 T-cells activation, recent thymic emigrants, activation/apoptosis and turnover of CD4 cells were assessed at baseline and during follow up. Univariate and multivariate associations with CD4 evolution were explored.

Results

Parameters significantly associated with CD4 depletion in cART-naïve group were: baseline level (p = 0.02) and variation (p = 0.002) of PD1 and Tim3 co-expression on CD8, and variation of CD95 expression on CD4 (p = 0.007). Parameters significantly associated with CD4 restoration in cART group were: baseline level of CD38+HLADR- subset of CD8 (p = 0.01), variation of PD1 expression on CD8 (p = 0.036), variation of Tim3 expression on CD4 (p = 0.039) and variation of CD95 expression on CD4 (p = 0.035).

Conclusions

Our results suggest that PD1 and Tim3 markers of exhaustion have a pivotal role in CD4 dynamics in HIV patients and its down-regulation would be a desirable effect of immunotherapies aimed to restore CD4 T-cell pool during progression of HIV infection.

Immune checkpoint blockade in infectious diseases

The upregulation of immune checkpoint molecules, such as programmed cell death protein 1 (PD1) and cytotoxic T lymphocyte antigen 4 (CTLA4), on immune cells occurs during acute infections, such as malaria, as well as during chronic persistent viral infections, including HIV and hepatitis B virus. These pathways are important for preventing immune-driven pathology but can also limit immune-mediated clearance of the infection. The recent success of immune checkpoint blockade in cancer therapy suggests that targeting these pathways would also be effective for preventing and treating a range of infectious diseases. Here, we review our current understanding of immune checkpoint pathways in the pathogenesis of infectious diseases and discuss the potential for therapeutically targeting these pathways in this setting.

Dynamics of CD4 and CD8 T-Cell Subsets and Inflammatory Biomarkers during Early and Chronic HIV Infection in Mozambican Adults

During primary HIV infection (PHI), there is a striking cascade response of inflammatory cytokines and many cells of the immune system show altered frequencies and signs of extensive activation. These changes have been shown to have a relevant role in predicting disease progression; however, the challenges of identifying PHI have resulted in a lack of critical information about the dynamics of early pathogenic events. We studied soluble inflammatory biomarkers and changes in T-cell subsets in individuals at PHI (n = 40), chronic HIV infection (CHI, n = 56), and HIV-uninfected (n = 58) recruited at the Manhiça District Hospital in Mozambique. Plasma levels of 49 biomarkers were determined by Luminex and ELISA. T-cell immunophenotyping was performed by multicolor flow cytometry. Plasma HIV viremia, CD4, and CD8 T cell counts underwent rapid stabilization after PHI. However, several immunological parameters, including Th1-Th17 CD4 T cells and activation or exhaustion of CD8 T cells continued decreasing until more than 9 months postinfection. Importantly, no sign of immunosenescence was observed over the first year of HIV infection. Levels of IP-10, MCP-1, BAFF, sCD14, tumor necrosis factor receptor-2, and TRAIL were significantly overexpressed at the first month of infection and underwent a prompt decrease in the subsequent months while, MIG and CD27 levels began to increase 1 month after infection and remained overexpressed for almost 1 year postinfection. Early levels of soluble biomarkers were significantly associated with subsequently exhausted CD4 T-cells or with CD8 T-cell activation. Despite rapid immune control of virus replication, the stabilization of the T-cell subsets occurs months after viremia and CD4 count plateau, suggesting persistent immune dysfunction and highlighting the potential benefit of early treatment initiation that could limit immunological damage.

Nivolumab Enhances In Vitro Effector Functions of PD-1+ T-Lymphocytes and Leishmania-Infected Human Myeloid Cells in a Host Cell-Dependent Manner

Functional impairment of T-cells and a concomitant augmented expression of programmed death-1 (PD-1) have been observed in visceral leishmaniasis patients, as well as in experimental models for visceral and cutaneous leishmaniasis. The PD-1/PD-1-ligand (PD-1/PD-L) interaction negatively regulates T-cell effector functions, which are required for parasite control during leishmaniasis. The aim of this study was to elucidate the impact of the PD-1/PD-L axis in a human primary in vitro infection model of Leishmania major (Lm). Blocking the PD-1/PD-L interaction with nivolumab increased T-cell proliferation and release of the proinflammatory cytokines TNFα and IFNγ during the cocultivation of Lm-infected human monocyte-derived macrophages (hMDMs) or dendritic cells (hMDDC) with autologous PD-1⁺-lymphocytes. As a consequence Lm infection decreased, being the most pronounced in hMDDC, compared to proinflammatory hMDM1 and anti-inflammatory hMDM2. Focusing on hMDDC, we could partially reverse effects mediated by PD-1 blockade by neutralizing TNFα but not by neutralizing IFNγ. Furthermore, PD-1 blockade increased intracellular expression of perforin, granulysin, and granzymes in proliferating CD4⁺-T-cells, which might be implicated in reduction of Lm-infected cells. In all, our data describe an important role for the PD-1/PD-L axis upon Lm infection using a human primary cell system. These data contribute to a better understanding of the PD-1-induced T-cell impairment during disease and its influence on immune effector mechanisms to combat Lm infection.

Immune Checkpoint Inhibitors in Melanoma and HIV Infection

Introduction:

Immunotherapy with immune checkpoint inhibitors increases the overall survival of patients with metastatic melanoma regardless of their oncogene addicted mutations. However, no data is available from clinical trials of effective therapies in subgroups of melanoma patients that carry chronic infective diseases such as HIV. Evidences suggest a key role of the immune checkpoint molecules as a mechanism of immune escape not only from melanoma but also from HIV host immune response.

Conclusion:

In this article, firstly, we will describe the role of the immune checkpoint molecules in HIV chronic infection. Secondly, we will summarize the most relevant clinical evidences utilizing immune checkpoint inhibitors for the treatment of melanoma patients. Lastly, we will discuss the potential implications as well as the potential applications of immune checkpoint molecule-based immunotherapy in patients with melanoma and HIV infection.

PD-1 Blockade Promotes Epitope Spreading in Anticancer CD8+ T Cell Responses by Preventing Fratricidal Death of Subdominant Clones To Relieve Immunodomination

The interactions between programmed death-1 (PD-1) and its ligands hamper tumor-specific CD8⁺ T cell (T_CD8) responses, and PD-1-based "checkpoint inhibitors" have shown promise in certain cancers, thus revitalizing interest in immunotherapy. PD-1-targeted therapies reverse T_CD8 exhaustion/anergy. However, whether they alter the epitope breadth of T_CD8 responses remains unclear. This is an important question because subdominant T_CD8 are more likely than immunodominant clones to escape tolerance mechanisms and may contribute to protective anticancer immunity. We have addressed this question in an in vivo model of T_CD8 responses to well-defined epitopes of a clinically relevant oncoprotein, large T Ag. We found that unlike other coinhibitory molecules (CTLA-4, LAG-3, TIM-3), PD-1 was highly expressed by subdominant T_CD8, which correlated with their propensity to favorably respond to PD-1/PD-1 ligand-1 (PD-L1)-blocking Abs. PD-1 blockade increased the size of subdominant T_CD8 clones at the peak of their primary response, and it also sustained their presence, thus giving rise to an enlarged memory pool. The expanded population was fully functional as judged by IFN-γ production and MHC class I-restricted cytotoxicity. The selective increase in subdominant T_CD8 clonal size was due to their enhanced survival, not proliferation. Further mechanistic studies utilizing peptide-pulsed dendritic cells, recombinant vaccinia viruses encoding full-length T Ag or epitope mingenes, and tumor cells expressing T Ag variants revealed that anti-PD-1 invigorates subdominant T_CD8 responses by relieving their lysis-dependent suppression by immunodominant T_CD8 To our knowledge, our work constitutes the first report that interfering with PD-1 signaling potentiates epitope spreading in tumor-specific responses, a finding with clear implications for cancer immunotherapy and vaccination.

Clinical Trial of the Anti-PD-L1 Antibody BMS-936559 in HIV-1 Infected Participants on Suppressive Antiretroviral Therapy

Background

Reversing immune exhaustion with an anti-PD-L1 antibody may improve human immunodeficiency virus type 1 (HIV-1)-specific immunity and increase clearance of HIV-1-expressing cells.

Methods

We conducted a phase I, randomized, double-blind, placebo-controlled, dose-escalating study of BMS-936559, including HIV-1-infected adults aged >18 to <70 years on suppressive antiretroviral therapy with CD4+ counts >350 cells/μL and detectable plasma HIV-1 RNA by single-copy assay. Data on single infusions of BMS-936559 (0.3 mg/kg) versus placebo are described. The primary outcomes were safety defined as any grade 3 or greater or immune-related adverse event (AE) and the change in HIV-1 Gag-specific CD8+ T cell responses from baseline to day 28 after infusion.

Results

Eight men enrolled: 6 received 0.3 mg/kg of BMS-936559, and 2 received placebo infusions. There were no BMS-936559-related grade 3 or greater AEs. In 1 participant, asymptomatic hypophysitis (a protocol-defined immune-related AE) was identified 266 days after BMS-936559 infusion; it resolved over time. The mean percentage of HIV-1 Gag-specific CD8+ T cells expressing interferon γ increased from baseline (0.09%) through day 28 (0.20%; P = .14), driven by substantial increases in 2 participants who received BMS-936559.

Conclusions

In this first evaluation of an immunologic checkpoint inhibitor in healthy HIV-1-infected persons, single low-dose BMS-936559 infusions appeared to enhance HIV-1-specific immunity in a subset of participants.

Clinical Trials Registration

NCT02028403.

New approaches for the enhancement of chimeric antigen receptors for the treatment of HIV

HIV infection continues to be a life-long chronic disease in spite of the success of antiretroviral therapy (ART) in controlling viral replication and preventing disease progression. However, because of the high cost of treatment, severe side effects, and inefficiency in curing the disease with ART, there is a call for alternative therapies that will provide a functional cure for HIV. Cytotoxic T lymphocytes (CTLs) are vital in the control and clearance of viral infections and therefore immune-based therapies have attempted to engineer HIV-specific CTLs that would be able to clear the infection from the body. The development of chimeric antigen receptors (CARs) provides an opportunity to engineer superior HIV-specific CTLs that will be independent of the major histocompatibility complex for target recognition. A CD4-based CAR has been previously tested in clinical trials to test the antiviral efficacy of peripheral T cells armed with this CD4-based CAR. The results from these clinical trials showed the safety and feasibility of CAR T cell therapy for HIV infection; however, minimal antiviral efficacy was seen. In this review, we will discuss the various strategies being developed to enhance the therapeutic potency of anti-HIV CARs with the goal of generating superior antiviral responses that will lead to life-long HIV immunity and clearance of the virus from the body.

Landscape review of current HIV 'kick and kill' cure research - some kicking, not enough killing

BACKGROUND

Current antiretroviral therapy (ART) used to treat human immunodeficiency virus (HIV) patients is life-long because it only suppresses de novo infections. Recent efforts to eliminate HIV have tested the ability of a number of agents to reactivate ('Kick') the well-known latent reservoir. This approach is rooted in the assumption that once these cells are reactivated the host's immune system itself will eliminate ('Kill') the virus. While many agents have been shown to reactivate large quantities of the latent reservoir, the impact on the size of the latent reservoir has been negligible. This suggests that the immune system is not sufficient to eliminate reactivated reservoirs. Thus, there is a need for more emphasis on 'kill' strategies in HIV cure research, and how these might work in combination with current or future kick strategies.

METHODS

We conducted a landscape review of HIV 'cure' clinical trials using 'kick and kill' approaches. We identified and reviewed current available clinical trial results in human participants as well as ongoing and planned clinical trials. We dichotomized trials by whether they did not include or include a 'kill' agent. We extracted potential reasons why the 'kill' is missing from current 'kick and kill' strategies. We subsequently summarized and reviewed current 'kill' strategies have entered the phase of clinical trial testing in human participants and highlighted those with the greatest promise.

RESULTS

The identified 'kick' trials only showed promise on surrogate measures activating latent T-cells, but did not show any positive effects on clinical 'cure' measures. Of the 'kill' agents currently being tested in clinical trials, early results have shown small but meaningful proportions of participants remaining off ART for several months with broadly neutralizing antibodies, as well as agents for regulating immune cell responses. A similar result was also recently observed in a trial combining a conventional 'kick' with a vaccine immune booster ('kill').

CONCLUSION

While an understanding of the efficacy of each individual component is crucial, no single 'kick' or 'kill' agent is likely to be a fully effective cure. Rather, the solution is likely found in a combination of multiple 'kick and kill' interventions.

Predict disease progression from T-cell phenotypes in northern pig-tailed macaques (Macaca leonina) during SIVmac239 infection

Macaca leonina (northern pig-tailed macaques, NPMs) have variable disease progression during SIVmac239 infection. In the present study, we analysed, for the first time, the correlations between T-cell phenotypes and disease progression in NPMs during SIVmac239 infection. In comparison to normal progressors (NPs), slow progressors (SPs) had lower chronic T-cell activation and exhaustion levels. In addition, SPs showed higher peripheral CD4⁺ T-cell count and CD4 : CD8 ratio, and lower plasma viral load than NPs. CD4⁺ T-cell count and CD4 : CD8 ratio decreased more sharply in NPs than in SPs. Furthermore, T cells in NPs were more highly differentiated, at least in acute infection, than in SPs. These results indicated that T-cell phenotypes were correlated with disease progression in SIVmac239-infected NPMs and these correlations may provide valuable guidance for the improvement of therapeutic strategies tested in NPMs.

An Immune Atlas of Clear Cell Renal Cell Carcinoma

Immune cells in the tumor microenvironment modulate cancer progression and are attractive therapeutic targets. Macrophages and T cells are key components of the microenvironment, yet their phenotypes and relationships in this ecosystem and to clinical outcomes are ill defined. We used mass cytometry with extensive antibody panels to perform in-depth immune profiling of samples from 73 clear cell renal cell carcinoma (ccRCC) patients and five healthy controls. In 3.5 million measured cells, we identified 17 tumor-associated macrophage phenotypes, 22 T cell phenotypes, and a distinct immune composition correlated with progression-free survival, thereby presenting an in-depth human atlas of the immune tumor microenvironment in this disease. This study revealed potential biomarkers and targets for immunotherapy development and validated tools that can be used for immune profiling of other tumor types.

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Mass cytometry reveals the immune cell diversity of the ccRCC tumor ecosystem

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PD-1⁺ cells display heterogeneous combinations of inhibitory receptors

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CD38⁺CD204⁺CD206⁻ tumor-associated macrophages correlate with immunosuppression

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A specific immune signature is linked to shorter progression-free survival

Intracellular HIV-1 RNA and CD4+ T-cell activation in patients starting antiretrovirals

OBJECTIVE

To assess if the reduction in HIV-1 RNA in CD4 T cells is correlated with the persistence of immune activation following early antiretroviral therapy (ART).

DESIGN

Clinical trial (NCT01285050).

METHODS

Next-generation sequencing was used to study total RNA from activated CD4 T cells (CD38 and human leukocyte antigen - antigen D related (HLA-DR) expressing) collected from 19 treatment-naïve HIV-1/hepatitis C virus-infected patients before and early after ART initiation (≥12 weeks after plasma HIV-1 RNA <50 copies/ml). To validate comparisons, pre and post-ART measures were adjusted for input RNA and overall read number.

RESULTS

As expected, ART use was associated with a median [interquartile range (IQR)] 4.3% (2.2-8.3) reduction in the proportion of activated CD4 T cells (P = 0.0008). Whereas in those activated CD4 T cells no consistent differences in overall gene expression were detected, interferon-stimulated gene expression declined (P < 2 × 10). Pre-ART, sorted activated CD4 T cells contained a median (IQR) of 959 (252-1614) HIV-1 reads/10 reads compared with 72 (55-152) HIV-1 reads/10 reads after at least 12 weeks of suppressive ART (P = 8 × 10). The decrease in HIV-1 reads in activated CD4 T cells was associated with the change in plasma HIV-1 RNA levels (r = 0.77, P = 2 × 10) and the change in the proportion of activated CD4 T cells (r = 0.70, P = 0.0016).

CONCLUSION

Months of ART led to a marked decrease in cell-associated HIV-1 RNA and interferon-stimulated genes expression in activated CD4 T cells that were strongly associated with the reduction in the proportion of activated CD4 T cells.

Immunosenescence and hurdles in the clinical management of older HIV-patients

People living with HIV (PLWH) who are treated with effective highly active antiretroviral therapy (HAART) have a similar life expectancy to the general population. Moreover, an increasing proportion of new HIV diagnoses are made in people older than 50 y. The number of older HIV-infected patients is thus constantly growing and it is expected that by 2030 around 70% of PLWH will be more than 50 y old. On the other hand, HIV infection itself is responsible for accelerated immunosenescence, a progressive decline of immune system function in both the adaptive and the innate arm, which impairs the ability of an individual to respond to infections and to give rise to long-term immunity; furthermore, older patients tend to have a worse immunological response to HAART. In this review we focus on the pathogenesis of HIV-induced immunosenescence and on the clinical management of older HIV-infected patients.

Immune Interventions to Eliminate the HIV Reservoir

Inducing HIV remission is a monumental challenge. A potential strategy is the "kick and kill" approach where latently infected cells are first activated to express viral proteins and then eliminated through cytopathic effects of HIV or immune-mediated killing. However, pre-existing immune responses to HIV cannot eradicate HIV infection due to the presence of escape variants, inadequate magnitude, and breadth of responses as well as immune exhaustion. The two major approaches to boost immune-mediated elimination of infected cells include enhancing cytotoxic T lymphocyte mediated killing and harnessing antibodies to eliminate HIV. Specific strategies include increasing the magnitude and breadth of T cell responses through therapeutic vaccinations, reversing the effects of T cell exhaustion using immune checkpoint inhibition, employing bispecific T cell targeting immunomodulatory proteins or dual-affinity re-targeting molecules to direct cytotoxic T lymphocytes to virus-expressing cells and broadly neutralizing antibody infusions. Methods to steer immune responses to tissue sites where latently infected cells are located need to be further explored. Ultimately, strategies to induce HIV remission must be tolerable, safe, and scalable in order to make a global impact.

Strategies to limit immune-activation in HIV patients

INTRODUCTION

Antiretroviral treatment of HIV infection reduces, but does not eliminate, viral replication and down modulates immune activation. The persistence of low level HIV replication in the host, nevertheless, drives a smouldering degree of immune activation that is observed throughout the natural history of disease and is the main driving force sustaining morbidity and mortality. Areas covered: Early start of antiretroviral therapy (ART) and intensive management of behavioural risk factors are possible but, at best, marginally successful ways to manage immune activation. We review alternative, possible strategies to reduce immune activation in HIV infection including timing of ART initiation and ART intensification to reduce HIV residual viremia; switch of ART to newer molecules with reduced toxicity; use of anti inflammatory/immunomodulatory agents and, finally, interventions aimed at modifying the composition of the microbiota. Expert commentary: Current therapeutic strategies to limit immune activation are only marginally successful. Because HIV eradication is currently impossible, intensive studies are needed to determine if and how immune activation can be silenced in HIV infection.