The Early Antibody-Dependent Cell-Mediated Cytotoxicity Response Is Associated With Lower Viral Set Point in Individuals With Primary HIV Infection

Adaptive NK Cells Rapidly Expand during Acute HIV Infection and Persist Despite Early Initiation of Antiretroviral Therapy

HIV is associated with NK cell dysfunction and expansion of adaptive-like NK cells that persist despite antiretroviral therapy (ART). We investigated the timing of NK cell perturbations during acute HIV infection and the impact of early ART initiation. PBMCs and plasma were obtained from people with HIV (PWH; all men who have sex with men; median age, 26.0 y) diagnosed during Fiebig stages I, II, III, or IV/V. Participants initiated ART a median of 3 d after diagnosis, and immunophenotyping was performed at diagnosis and longitudinally after ART. Anti-CMV Abs were assessed by ELISA. Samples from matched HIV-uninfected males were also analyzed. Proportions of adaptive NK cells (A-NKs; defined as Fcε-Receptor-1γ-) were expanded at HIV diagnosis at all Fiebig stages (pooled median 66% versus 25% for controls; p < 0.001) and were not altered by early ART initiation. Abs to CMV immediate early protein were elevated in PWH diagnosed in Fiebig stages III and IV/V (p < 0.03 for both). Proportions of A-NKs defined as either Fcε-Receptor-1γ- or NKG2C+/CD57+ were significantly associated with HIV DNA levels at diagnosis (p = 0.046 and 0.029, respectively) and trended toward an association after 48 wk of ART. Proportions of activated HLA-DR+/CD38+ NK cells remained elevated in PWH despite early ART initiation. NK cell activation and A-NK expansion occur very early after HIV transmission, before T cell activation, and are not altered by ART initiation during acute infection. A-NKs may contribute to HIV control and thus be useful for HIV cure.

Bispecific antibodies promote natural killer cell-mediated elimination of HIV-1 reservoir cells

The persistence of CD4+ T cells carrying latent human immunodeficiency virus-1 (HIV-1) proviruses is the main barrier to a cure. New therapeutics to enhance HIV-1-specific immune responses and clear infected cells will probably be necessary to achieve reduction of the latent reservoir. In the present study, we report two single-chain diabodies (scDbs) that target the HIV-1 envelope protein (Env) and the human type III Fcγ receptor (CD16). We show that the scDbs promoted robust and HIV-1-specific natural killer (NK) cell activation and NK cell-mediated lysis of infected cells. Cocultures of CD4+ T cells from people with HIV-1 on antiretroviral therapy (ART) with autologous NK cells and the scDbs resulted in marked elimination of reservoir cells that was dependent on latency reversal. Treatment of human interleukin-15 transgenic NSG mice with one of the scDbs after ART initiation enhanced NK cell activity and reduced reservoir size. Thus, HIV-1-specific scDbs merit further evaluation as potential therapeutics for clearance of the latent reservoir.

Dietary Iron Intake and HIV-Related Outcomes Among Adults Initiating Antiretroviral Therapy in Tanzania

OBJECTIVE

Anemia is highly prevalent among people living with HIV (PLWHIV) and is often due to iron deficiency. This study evaluated the relationship of dietary iron intake levels and sources with mortality and clinical outcomes among adults initiating HAART.

DESIGN

We conducted a secondary analysis of a multivitamin supplementation trial among 2293 PLWHIV initiating HAART in Dar es Salaam, Tanzania.

METHODS

Dietary iron intake was assessed with a food frequency questionnaire at HAART initiation, and participants followed until death or censoring. Total, animal-, and plant-sourced iron were categorized into quartiles. Intake of food groups was categorized into 0-1, 2-3, and ≥4 servings/wk. Cox proportional hazards models estimated hazard ratios for mortality and incident clinical outcomes.

RESULTS

There were 175 deaths (8%). Red meat intake was associated with a lower risk of all-cause mortality (HR: 0.54; 95% CI: 0.35 to 0.83), AIDS-related mortality (HR: 0.49; 95% CI: 0.28 to 0.85), and severe anemia (HR: 0.57; 95% CI: 0.35 to 0.91), when intake ≥4 servings/wk, compared with 0-1 servings/wk. Legume intake was a lower risk of associated with all-cause mortality (HR: 0.49; 95% CI: 0.31 to 0.77) and AIDS-related mortality (HR: 0.37; 95% CI: 0.23 to 0.61), when intake ≥4 servings/wk, compared with 0-1 servings/wk. Although total dietary iron and overall plant-sourced iron intake were not associated with the risk of mortality or HIV-related outcomes, the highest quartile of animal-sourced iron intake was associated with a lower risk of all-cause mortality (HR: 0.56; 95% CI: 0.35 to 0.90) and a lower risk of AIDS-related mortality (HR: 0.50; 95% CI: 0.30 to 0.90), compared with the lowest quartile.

CONCLUSION

Intake of iron-rich food groups may be associated with a lower risk of mortality and critical HIV-related outcomes among adults initiating HAART.

TRIAL REGISTRATION

The parent trial was registered at Clinicaltrials.gov . Identifier: NCT00383669.

Reconstruction of a polyclonal ADCC antibody repertoire from an HIV-1 non-transmitting mother

Human natural history and vaccine studies support a protective role of antibody dependent cellular cytotoxicity (ADCC) activity against many infectious diseases. One setting where this has consistently been observed is in HIV-1 vertical transmission, where passively acquired ADCC activity in HIV-exposed infants has correlated with reduced acquisition risk and reduced pathogenesis in HIV+ infants. However, the characteristics of HIV-specific antibodies comprising a maternal plasma ADCC response are not well understood. Here, we reconstructed monoclonal antibodies (mAbs) from memory B cells from late pregnancy in mother MG540, who did not transmit HIV to her infant despite several high-risk factors. Twenty mAbs representing 14 clonal families were reconstructed, which mediated ADCC and recognized multiple HIV Envelope epitopes. In experiments using Fc-defective variants, only combinations of several mAbs accounted for the majority of plasma ADCC of MG540 and her infant. We present these mAbs as evidence of a polyclonal repertoire with potent HIV-directed ADCC activity.

Evolution of Antibody Responses in HIV-1 CRF01_AE Acute Infection: Founder Envelope V1V2 Impacts the Timing and Magnitude of Autologous Neutralizing Antibodies

Understanding the dynamics of early immune responses to HIV-1 infection, including the evolution of initial neutralizing and antibody-dependent cellular cytotoxicity (ADCC)-mediating antibodies, will inform HIV vaccine design. In this study, we assess the development of autologous neutralizing antibodies (ANAbs) against founder envelopes (Envs) from 18 participants with HIV-1 CRF01_AE acute infection. The timing of ANAb development directly associated with the magnitude of the longitudinal ANAb response. Participants that developed ANAbs within 6 months of infection had significantly higher ANAb responses at 1 year (50% inhibitory concentration [IC50] geometric mean titer [GMT] = 2,010 versus 184; P = 0.001) and 2 years (GMT = 3,479 versus 340; P = 0.015), compared to participants that developed ANAb responses after 6 months. Participants with later development of ANAb tended to develop an earlier, potent heterologous tier 1 (92TH023) neutralizing antibody (NAb) response (P = 0.049). CRF01_AE founder Env V1V2 loop lengths correlated indirectly with the timing (P = 0.002, r = -0.675) and directly with magnitude (P = 0.005, r = 0.635) of ANAb responses; Envs with longer V1V2 loop lengths elicited earlier and more potent ANAb responses. While ANAb responses did not associate with viral load, the viral load set point correlated directly with neutralization of the heterologous 92TH023 strain (P = 0.007, r = 0.638). In contrast, a striking inverse correlation was observed between viral load set point and peak ADCC against heterologous 92TH023 Env strain (P = 0.0005, r = -0.738). These data indicate that specific antibody functions can be differentially related to viral load set point and may affect HIV-1 pathogenesis. Exploiting Env properties, such as V1V2 length, could facilitate development of subtype-specific vaccines that elicit more effective immune responses and improved protection. IMPORTANCE Development of an effective HIV-1 vaccine will be facilitated by better understanding the dynamics between the founder virus and the early humoral responses. Variations between subtypes may influence the evolution of immune responses and should be considered as we strive to understand these dynamics. In this study, autologous founder envelope neutralization and heterologous functional humoral responses were evaluated after acute infection by HIV-1 CRF01_AE, a subtype that has not been thoroughly characterized. The evolution of these humoral responses was assessed in relation to envelope characteristics, magnitude of elicited immune responses, and viral load. Understanding immune parameters in natural infection will improve our understanding of protective responses and aid in the development of immunogens that elicit protective functional antibodies. Advancing our knowledge of correlates of positive clinical outcomes should lead to the design of more efficacious vaccines.

Natural killer cells during acute HIV-1 infection: clues for HIV-1 prevention and therapy

Despite progress in preexposure prophylaxis, the number of newly diagnosed cases with HIV-1 remains high, highlighting the urgent need for preventive and therapeutic strategies to reduce HIV-1 acquisition and limit disease progression. Early immunological events, occurring during acute infection, are key determinants of the outcome and course of disease. Understanding early immune responses occurring before viral set-point is established, is critical to identify potential targets for prophylactic and therapeutic approaches. Natural killer (NK) cells represent a key cellular component of innate immunity and contribute to the early host defence against HIV-1 infection, modulating the pathogenesis of acute HIV-1 infection (AHI). Emerging studies have identified tools for harnessing NK cell responses and expanding specialized NK subpopulations with adaptive/memory features, paving the way for development of novel HIV-1 therapeutics. This review highlights the knowns and unknowns regarding the role of NK cell subsets in the containment of acute HIV-1 infection, and summarizes recent advances in selectively augmenting NK cell functions through prophylactic and therapeutic interventions.

Antibody-Dependent Enhancement: ″Evil″ Antibodies Favorable for Viral Infections

The pandemics caused by emerging viruses such as severe acute respiratory syndrome coronavirus 2 result in severe disruptions to public health. Vaccines and antibody drugs play essential roles in the control and prevention of emerging infectious diseases. However, in contrast with the neutralizing antibodies (NAbs), sub- or non-NAbs may facilitate the virus to enter the cells and enhance viral infection, which is termed antibody-dependent enhancement (ADE). The ADE of most virus infections is mediated by the Fc receptors (FcRs) expressed on the myeloid cells, while others are developed by other mechanisms, such as complement receptor-mediated ADE. In this review, we comprehensively analyzed the characteristics of the viruses inducing FcRs-mediated ADE and the new molecular mechanisms of ADE involved in the virus entry, immune response, and transcription modulation, which will provide insights into viral pathogenicity and the development of safer vaccines and effective antibody drugs against the emerging viruses inducing ADE.

Impact of adjuvants on the biophysical and functional characteristics of HIV vaccine-elicited antibodies in humans

Adjuvants can alter the magnitude, characteristics, and persistence of the humoral response to protein vaccination. HIV vaccination might benefit from tailored adjuvant choice as raising a durable and protective response to vaccination has been exceptionally challenging. Analysis of trials of partially effective HIV vaccines have identified features of the immune response that correlate with decreased risk, including high titers of V1V2-binding IgG and IgG3 responses with low titers of V1V2-binding IgA responses and enhanced Fc effector functions, notably antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). However, there has been limited opportunity to compare the effect of different adjuvants on these activities in humans. Here, samples from the AVEG015 study, a phase 1 trial in which participants (n = 112) were immunized with gp120SF-2 and one of six different adjuvants or combinations thereof were assessed for antibody titer, biophysical features, and diverse effector functions. Three adjuvants, MF59 + MTP-PE, SAF/2, and SAF/2 + MDP, increased the peak magnitude and durability of antigen-specific IgG3, IgA, FcγR-binding responses and ADCP activity, as compared to alum. While multiple adjuvants increased the titer of IgG, IgG3, and IgA responses, none consistently altered the balance of IgG to IgA or IgG3 to IgA. Linear regression analysis identified biophysical features including gp120-specific IgG and FcγR-binding responses that could predict functional activity, and network analysis identified coordinated aspects of the humoral response. These analyses reveal the ability of adjuvants to drive the character and function of the humoral response despite limitations of small sample size and immune variability in this human clinical trial.

Engaging innate immunity in HIV-1 cure strategies

Combination antiretroviral therapy (ART) can block multiple stages of the HIV-1 life cycle to prevent progression to AIDS in people living with HIV-1. However, owing to the persistence of a reservoir of latently infected CD4⁺ T cells, life-long ART is necessary to prevent viral rebound. One strategy currently under consideration for curing HIV-1 infection is known as 'shock and kill'. This strategy uses latency-reversing agents to induce expression of HIV-1 genes, allowing for infected cells to be cleared by cytolytic immune cells. The role of innate immunity in HIV-1 pathogenesis is best understood in the context of acute infection. Here, we suggest that innate immunity can also be used to improve the efficacy of HIV-1 cure strategies, with a particular focus on dendritic cells (DCs) and natural killer cells. We discuss novel latency-reversing agents targeting DCs as well as DC-based strategies to enhance the clearance of infected cells by CD8⁺ T cells and strategies to improve the killing activity of natural killer cells.

T-Follicular-Like CD8+ T Cell Responses in Chronic HIV Infection Are Associated With Virus Control and Antibody Isotype Switching to IgG

T cell responses are considered critical for the in vivo control of HIV, but the contribution of different T cell subsets to this control remains unclear. Using a boosted flow cytometric approach that is able to differentiate CD4+ and CD8+ T cell Th1/Tc1, Th2/Tc2, Th17/Tc17, Treg and Tfh/Tfc-like HIV-specific T cell populations, we identified CD8+ Tfc responses that were related to HIV plasma viral loads and associated with rate of antibody isotype class switching to IgG. This favorable balance towards IgG responses positively correlated with increased virus neutralization, higher avidity of neutralizing antibodies and more potent antibody-dependent cell cytotoxicity (ADCC) in PBMCs from HIV controllers compared to non-controllers. Our results identified the CD8+ Tfc-like T-cell response as a component of effective virus control which could possibly be exploited therapeutically.

Natural Killer Cells in Antibody Independent and Antibody Dependent HIV Control

Infection with the human immunodeficiency virus (HIV), when left untreated, typically leads to disease progression towards acquired immunodeficiency syndrome. Some people living with HIV (PLWH) control their virus to levels below the limit of detection of standard viral load assays, without treatment. As such, they represent examples of a functional HIV cure. These individuals, called Elite Controllers (ECs), are rare, making up <1% of PLWH. Genome wide association studies mapped genes in the major histocompatibility complex (MHC) class I region as important in HIV control. ECs have potent virus specific CD8⁺ T cell responses often restricted by protective MHC class I antigens. Natural Killer (NK) cells are innate immune cells whose activation state depends on the integration of activating and inhibitory signals arising from cell surface receptors interacting with their ligands on neighboring cells. Inhibitory NK cell receptors also use a subset of MHC class I antigens as ligands. This interaction educates NK cells, priming them to respond to HIV infected cell with reduced MHC class I antigen expression levels. NK cells can also be activated through the crosslinking of the activating NK cell receptor, CD16, which binds the fragment crystallizable portion of immunoglobulin G. This mode of activation confers NK cells with specificity to HIV infected cells when the antigen binding portion of CD16 bound immunoglobulin G recognizes HIV Envelope on infected cells. Here, we review the role of NK cells in antibody independent and antibody dependent HIV control.

Negative Regulation and Protective Function of Natural Killer Cells in HIV Infection: Two Sides of a Coin

Natural killer (NK) cells play an important immunologic role, targeting tumors and virus-infected cells; however, NK cells do not impede the progression of human immunodeficiency virus (HIV) infection. In HIV infection, NK cells exhibit impaired functions and negatively regulate other immune cell responses, although NK cells can kill HIV-infected cells and thereby suppress HIV replication. Considerable recent research has emerged regarding NK cells in the areas of immune checkpoints, negative regulation, antibody-dependent cell-mediated cytotoxicity and HIV reservoirs during HIV infection; however, no overall summary of these factors is available. This review focuses on several important aspects of NK cells in relation to HIV infection, including changes in NK cell count, subpopulations, and immune checkpoints, as well as abnormalities in NK cell functions and NK cell negative regulation. The protective function of NK cells in inhibiting HIV replication to reduce the viral reservoir and approaches for enhancing NK cell functions are also summarized.

Recent insights into Fc-mediated effector responses to HIV-1

PURPOSE OF REVIEW

Recent work defining Fc-mediated effector functions for both viral control and protection against infection is summarized and considered along with new strategies to drive robust Fc-mediated responses.

RECENT FINDINGS

In new human and nonhuman primate (NHP) vaccine trials as well as studies of natural infection, Fc-mediated effector responses have sometimes been observed to correlate with decreased risk of infection or with better clinical outcomes, suggesting a potential role for these responses in HIV-1 prevention and therapy. Recent highlights include use of antibody-dependent cellular cytotoxicity-sensitizing CD4-induced mimetic compounds, novel V1V2 immunogens, passive transfer studies, and vaccine regimens that successfully elicited Fc-mediated responses and were reported to decrease risk of infection in challenge studies in NHPs. Lastly, detailed studies of IgG3 forms of HIV-specific antibodies have reported that both neutralizing and Fc-mediated responses can be increased relative to the more prevalent IgG1 subclass.

SUMMARY

Successful harmonization of neutralizing and Fc-mediated responses may make key contributions to the goal of reducing HIV-1 infection via active and passive vaccination. New studies continue to highlight the importance of Fc-mediated antibody responses as correlates of decreased risk of infection and suggest enhanced phagocytosis is a potential mechanism of reduced risk of infection associated with human IgG3 responses. Results from recent studies may help guide the rational design of therapies and vaccines that aim to specifically leverage antibody effector function.

Humoral immune responses to AAV gene therapy in the ocular compartment

Viral vectors can be utilised to deliver therapeutic genes to diseased cells. Adeno-associated virus (AAV) is a commonly used viral vector that is favoured for its ability to infect a wide range of tissues whilst displaying limited toxicity and immunogenicity. Most humans harbour anti-AAV neutralising antibodies (NAbs) due to subclinical infections by wild-type virus during infancy and these pre-existing NAbs can limit the efficiency of gene transfer depending on the target cell type, route of administration and choice of serotype. Vector administration can also result in de novo NAb synthesis that could limit the opportunity for repeated gene transfer to diseased sites. A number of strategies have been described in preclinical models that could circumvent NAb responses in humans, however, the successful translation of these innovations into the clinical arena has been limited. Here, we provide a comprehensive review of the humoral immune response to AAV gene therapy in the ocular compartment. We cover basic AAV biology and clinical application, the role of pre-existing and induced NAbs, and possible approaches to overcoming antibody responses. We conclude with a framework for a comprehensive strategy for circumventing humoral immune responses to AAV in the future.

First complete-genome documentation of HIV-1 intersubtype superinfection with transmissions of diverse recombinants over time to five recipients

Human immunodeficiency virus type 1 (HIV-1) recombinants in the world are believed to be generated through recombination between distinct HIV-1 strains among coinfection or superinfection cases. However, direct evidence to support transmission of HIV-1 recombinants from a coinfected/superinfected donor to putative recipient is lacking. Here, we report on the origin and evolutionary relationship between a set of recombinants from a CRF01_AE/CRF07_BC superinfected putative donor and diverse CRF01_AE/CRF07_BC recombinants from five putative recipients. Interviews on sociodemographic characteristics and sexual behaviors for these six HIV-1-infected men who have sex with men showed that they had similar ways of partner seeking: online dating sites and social circles. Phylogenetic and recombination analyses demonstrated that the near-full-length genome sequences from six patients formed a monophyletic cluster different from known HIV-1 genotypes in maximum likelihood phylogenetic trees, were all composed of CRF01_AE and CRF07_BC fragments with two common breakpoints on env, and shared 4-7 breakpoints with each other. Moreover, 3' half-genomes of recombinant strains from five recipients had identical/similar recombinant structures with strains at longitudinal samples from the superinfected donor. Recombinants from the donor were paraphyletic, whereas five recipients were monophyletic or polyphyletic in the maximum clade credibility tree. Bayesian analyses confirmed that the estimated time to the most recent common ancestor (tMRCA) of CRF01_AE and CRF07_BC strains of the donor was 2009.2 and 2010.7, respectively, and all were earlier than the emergence of recombinants from five recipients. Our results demonstrated that the closely related unique recombinant forms of HIV-1 might be the descendent of a series of recombinants generated gradually in a superinfected patient. This finding highlights the importance of early initiation of antiretroviral therapy as well as tracing and testing of partners in patients with multiple HIV-1 infection.

Development and optimization of a Zika virus antibody-dependent cell-mediated cytotoxicity (ADCC) assay

Zika virus (ZIKV) has become a global public health issue due to its teratogenicity and ability to cause Guillain-Barré syndrome in adults. Although anti-ZIKV envelope protein neutralizing antibodies correlate with protection, the non-neutralizing function of ZIKV antibodies including antibody-dependent cell-mediated cytotoxicity (ADCC) is incompletely understood. To study the role of ADCC antibodies during ZIKV infections, we generated a stably transfected, dual-reporter target cell line with inducible expression of a chimeric ZIKV prM-E protein on the cell surface as the target cell for the assay. By using this assay, nine of ten serum samples from ZIKV-infected patients had >20% ADCC killing of target cells, whereas none of the 12 healthy control sera had >10% ADCC killing. We also observed a time-dependent ADCC response in 2 patients with Zika. This demonstrates that this assay can detect ZIKV ADCC with high sensitivity and specificity, which could be useful for measurement of ADCC responses to ZIKV infection or vaccination.

Natural killer cell counts in primary HIV infection predicts disease progression and immune restoration after treatment

The relationship between NK cell counts during primary infection and disease progression or immune restoration after antiretroviral treatment (ART) was explored. We followed 462 individuals with HIV infection and measured their NK, CD4⁺ T, CD8⁺ T cell counts and viral loads. Our data showed that individuals with high NK cell counts had much lower viral loads and higher CD4⁺ T cell counts. NK cell counts during primary infection were negatively correlated with viral set-point and viral loads at one-year-infection point, and positively correlated with CD4⁺ T cell counts at one-year-infection and one-year-ART point. Moreover, the NK cell counts during primary infection can predict HIV disease progression and immune restoration after ART. In conclusion, NK cell counts during primary infection represents a potential predictive biomarker to predict HIV disease prognosis in the clinic.

A role for antibodies in natural HIV control

PURPOSE OF REVIEW

Rare patients naturally control HIV replication without antiretroviral therapy. Understanding the mechanisms implicated in natural HIV control will inform the development of immunotherapies against HIV. Elite controllers are known for developing efficient antiviral T-cell responses, but recent findings suggest that antibody responses also play a significant role in HIV control. We review the key studies that uncovered a potent memory B-cell response and highly functional anti-HIV antibodies in elite controllers, and explore the mechanisms that may account for the distinct properties of their humoral response.

RECENT FINDINGS

Elite controllers maintain a large HIV-specific memory B-cell pool that is sustained by efficient T follicular helper function. Neutralizing antibody rarely show high titers in controllers, but seem capable, at least in certain cases, of neutralizing contemporaneous viral strains. In addition, elite controllers display a unique HIV-specific antibody profile in terms of isotype, antigen specificity, and glycosylation pattern, resulting in polyfunctional antibody effector functions that may promote infected cell lysis and prime effectors of the antiviral immune response.

SUMMARY

Lessons from elite controller studies argue for the importance of integrating the many parameters defining a polyfunctional antibody response when evaluating candidate vaccines and immunotherapeutic approaches directed at HIV.

Elevated CD54 Expression Renders CD4+ T Cells Susceptible to Natural Killer Cell-Mediated Killing

BACKGROUND

Natural killer (NK) cells are an important type of effector cell in the innate immune response, and also have a role in regulation of the adaptive immune response. Several studies have indicated that NK cells may influence CD4+ T cells during HIV infection.

METHODS

In total, 51 HIV-infected individuals and 15 healthy controls participated in this study. We performed the flow cytometry assays and real-time PCR for the phenotypic analysis and the functional assays of NK cell-mediated deletion of CD4+ T cells, phosphorylation of nuclear factor-κB (NF-κB/p65) and the intervention of metformin.

RESULTS

Here we detected high CD54 expression on CD4+ T cells in HIV-infected individuals, and demonstrate that upregulated CD54 is associated with disease progression in individuals infected with HIV. We also show that CD54 expression leads to the deletion of CD4+ T cells by NK cells in vitro, and that this is modulated by NF-κB/p65 signaling. Further, we demonstrate that metformin can suppress CD54 expression on CD4+ T cells by inhibiting NF-κB/p65 phosphorylation.

CONCLUSIONS

Our data suggest that further studies to evaluate the potential role of metformin as adjunctive therapy to reconstitute immune function in HIV-infected individuals are warranted.

Higher Baseline ADCC Responses in Chronic Nonprogressive HIV Infection Are Associated with Reduced HIV Burden in Later Course of Disease

The importance of anti-HIV antibodies mediating antibody-dependent cell-mediated cytotoxicity (ADCC) in protective immunity against HIV is recognized recently. The purpose of this study was to measure the functional ADCC response at different stages of HIV infection in a well-defined HIV+ cohort, including 20 recently infected individuals, 30 with long-term slow-progressive, 24 with short-term slow-progressive and 32 with progressive HIV infection using a rapid fluorometric ADCC assay. The antibodies mediating ADCC were found in all disease stages. These antibodies were detectable at as early as 25 days after the estimated date of infection, however, did not influence the viral load set point probably indicating no major influence on the early course of the disease. However, the frequency and magnitude of functional ADCC responses were associated with higher CD4⁺T cell count and lower viral load and were significantly lower in progressors compared with other groups. The usefulness of the ADCC responses in longer viral control was assessed in a subset of participants with slowly progressing HIV infection. In these individuals, the ADCC responses observed at the visit 1 were found to be increased over time and were associated with lower plasma viral load estimated 4 to 15 years later in the disease course. Overall, the study findings confirm the role of ADCC antibodies in reducing the viral burden and also indicate the probable role of sustained functional ADCC responses in reducing the viral burden during the later period of HIV infection.

The combination of CXCL9, CXCL10 and CXCL11 levels during primary HIV infection predicts HIV disease progression

Background

Chemokines are small chemotactic cytokines involved in inflammation, cell migration, and immune regulation in both physiological and pathological contexts. Here, we investigated the profile of chemokines during primary HIV infection (PHI).

Methods

Fifty-four participants with blood samples before and during HIV infection and clinical information available were selected from an HIV-negative man who have sex with men (MSM) prospective cohort. Thirty chemokines and 10 cytokines were measured pre- and post-HIV infection in the same individuals using a Bio-Plex Pro™ Human Chemokine Panel.

Results

Levels of 18 chemokines/cytokines changed significantly during PHI relative to pre-HIV infection levels; 14 were up-regulated and 4 down-regulated. Among them, CXCL9, CXCL10, and CXCL11 were the most prominently raised. Levels of CXCL9 and CXCL10 were much higher in the high-set point group (log viral load (lgVL) ≥ 4.5) than those in the low-set point group (lgVL < 4.5) and levels of CXCL9, CXCL10, and CXCL11 were higher in the low-CD4⁺ T-cell count group (CD4⁺ T-cell count ≥ 500). A formula to predict HIV disease progression using a combination panel comprising CXCL9, CXCL10, and CXCL11 was developed, where risk score = 0.007 × CXCL9 + 0.004 × CXCL10 − 0.033 × CXCL11 − 1.724, with risk score values higher than the cutoff threshold (0.5211) indicating more rapid HIV disease progression.

Conclusions

A panel of plasma CXCL9, CXCL10, and CXCL11 measured during primary HIV-1 infection could predict long-term HIV disease prognosis in an MSM group and has potential as a novel biomarker in the clinic.

Deficient IL-2 Produced by Activated CD56+ T Cells Contributes to Impaired NK Cell-Mediated ADCC Function in Chronic HIV-1 Infection

Background: Antibody-dependent cellular cytotoxicity (ADCC), which mainly mediated by natural killer (NK) cells, may play a critical role in human immunodeficiency virus type-1 (HIV-1) disease progression. However, the potential mechanisms that affecting NK-mediated ADCC response are still not well-elucidated. Methods: Antigen-antibody complex model of Ab-opsonized P815 cells was adopted to induce a typical non-specific ADCC response. The capacities of HIV-1 specific NK-ADCC were measured by using the combination model of gp120 protein and plasma of HIV-1 elite controllers. The levels of plasma cytokine were measured by ELISA. Anti-IL-2 blocking antibody was used to analyze the impact of activated CD56⁺ T cells on NK-ADCC response. Results: IL-2, IL-15, IFN-α, and IFN-β could effectively enhance the non-specific and HIV-1-specific NK-ADCC responses. Compared with healthy controls, HIV-1-infected patients showed decreased plasma IL-2 levels, while no differences of plasma IFN-α, IL-15, and IFN-β were presented. IL-2 production was detected from CD56⁺ T cells activated through antibody-dependent manner. The capability of NK-ADCC could be weakened by blocking IL-2 secretion from activated CD56⁺ T cells. Although no difference of frequencies of CD56⁺ T cells was found between HIV-1-infected patients and healthy controls, deficient IL-2 secretion from activated CD56⁺ T were found in chronic HIV-1 infection. Conclusions: The impaired ability of activated CD56⁺ T cells to secreting IL-2 might contribute to the attenuated NK cell-mediated ADCC function in HIV-1 infection.

The Antibodiome-Mapping the Humoral Immune Response to HIV

PURPOSE OF REVIEW

The design of an HIV vaccine remains an elusive but top priority. Data from the non-human primate model and the first moderately protective HIV vaccine trial (RV144) point to a role for qualitative changes in humoral immune functions in protection from infection. Here, we review the current understanding of the antibody response throughout HIV infection, the known correlates of protection, and current strategies to manipulate antibodies to put an end to the epidemic.

RECENT FINDINGS

Recent studies point to innate immune-recruiting antibody function in preventing infection as well as controlling viremia following infection. These data have begun to inform next-generation design of HIV vaccines and antibody therapies by uncovering new viral targets and antibody architectures to improve potency and breadth. Emerging data illustrate a role for innate immune recruiting-antibodies in conferring protection against HIV infection as well as promoting viral control and clearance, offering an unprecedented opportunity to modulate and improve antibody function to fight HIV more effectively.