Barriers to a cure for HIV: new ways to target and eradicate HIV-1 reservoirs

The Increase of the Magnitude of Spontaneous Viral Blips in Some Participants of Phase II Clinical Trial of Therapeutic Optimized HIV DNA Vaccine Candidate

We developed a candidate DNA vaccine called “DNA-4”consisting of 4 plasmid DNAs encoding Nef, Gag, Pol(rt), and gp140 HIV-1 proteins. The vaccine was found to be safe and immunogenic in a phase I clinical trial. Here we present the results of a phase II clinical trial of “DNA-4”. This was a multicenter, double-blind, placebo-controlled clinical trial of safety, and dose selection of “DNA-4” in HIV-1 infected people receiving antiretroviral therapy (ART). Fifty-four patients were randomized into 3 groups (17 patients—group DNA-4 0.25 mg, 17 patients—group DNA-4 0.5 mg, 20 patients—the placebo group). All patients were immunized 4 times on days 0, 7, 11, and 15 followed by a 24-week follow-up period. “DNA-4” was found to be safe and well-tolerated at doses of 0.25 mg and 0.5 mg. We found that the amplitudes of the spontaneous viral load increases in three patients immunized with the candidate DNA vaccine were much higher than that in placebo group—2800, 180,000 and 709 copies/mL, suggesting a possible influence of therapeutic DNA vaccination on viral reservoirs in some patients on ART. We hypothesize that this influence was associated with the reactivation of proviral genomes.

An Omics Approach to Extracellular Vesicles from HIV-1 Infected Cells

Human Immunodeficiency Virus-1 (HIV-1) is the causative agent of Acquired Immunodeficiency Syndrome (AIDS), infecting nearly 37 million people worldwide. Currently, there is no definitive cure, mainly due to HIV-1's ability to enact latency. Our previous work has shown that exosomes, a small extracellular vesicle, from uninfected cells can activate HIV-1 in latent cells, leading to increased mostly short and some long HIV-1 RNA transcripts. This is consistent with the notion that none of the FDA-approved antiretroviral drugs used today in the clinic are transcription inhibitors. Furthermore, these HIV-1 transcripts can be packaged into exosomes and released from the infected cell. Here, we examined the differences in protein and nucleic acid content between exosomes from uninfected and HIV-1-infected cells. We found increased cyclin-dependent kinases, among other kinases, in exosomes from infected T-cells while other kinases were present in exosomes from infected monocytes. Additionally, we found a series of short antisense HIV-1 RNA from the 3' LTR that appears heavily mutated in exosomes from HIV-1-infected cells along with the presence of cellular noncoding RNAs and cellular miRNAs. Both physical and functional validations were performed on some of the key findings. Collectively, our data indicate distinct differences in protein and RNA content between exosomes from uninfected and HIV-1-infected cells, which can lead to different functional outcomes in recipient cells.

In Silico Design and Immunologic Evaluation of HIV-1 p24-Nef Fusion Protein to Approach a Therapeutic Vaccine Candidate

Background:

Acquired immune deficiency syndrome (HIV/AIDS) has been a major glob-al health concern for over 38 years. No safe and effective preventive or therapeutic vaccine has been developed although many products have been investigated. Computational methods have facilitated vaccine developments in recent decades. Among HIV-1 proteins, p24 and Nef are two suitable targets to provoke the cellular immune response. However, the fusion form of these two proteins has not been analyzed in silico yet.

Objective:

This study aimed at the evaluation of possible fusion forms of p24 and Nef in order to achieve a potential therapeutic subunit vaccine against HIV-1.

Method:

In this study, various computational approaches have been applied to predict the most effec-tive fusion form of p24-Nef including CTL (Cytotoxic T lymphocytes) response, immunogenicity, conservation and population coverage. Moreover, binding to MHC (Major histocompatibility com-plex) molecules was assessed in both human and BALB/c.

Results:

After analyzing six possible fusion protein forms using AAY linker, we came up with the most practical form of p24 from 80 to 231 and Nef from 120 to 150 regions (according to their refer-ence sequence of HXB2 strain) using an AAY linker, based on their peptides affinity to MHC mole-cules which are located in a conserved region among different virus clades. The selected fusion protein contains seventeen MHC I antigenic epitopes, among them KRWIILGLN, YKRWIILGL, DIAG-TTSTL and FPDWQNYTP are fully conserved between the virus clades. Furthermore, analyzed class I CTL epitopes showed greater affinity binding to HLA-B 57*01, HLA-B*51:01 and HLA-B 27*02 molecules. The population coverage with the rate of >70% coverage in the Persian population supports this truncated form as an appropriate candidate against HIV-I virus.

Conclusion:

The predicted fusion protein, p24-AAY-Nef in a truncated form with a high rate of T cell epitopes and high conservancy rate among different clades, provides a helpful model for developing a therapeutic vaccine candidate against HIV-1.

Induction of Follicular-Like CXCR5+ CD8+ T Cells by TGF-β1/IL-23 Is Limited During HIV Infection

Follicular CD4⁺ T cells are the main HIV reservoirs due to, among other factors, the low frequency of CD8⁺ T cells in lymphoid follicles. Follicular CXCR5⁺ CD8⁺ T cells are associated with HIV control, but their differentiation conditions are yet undefined. In this study, we explored the in vitro effect of transforming growth factor (TGF)-β1, interleukin (IL)-12, and IL-23 on the induction of CXCR5, the follicle homing receptor, in human circulating CD8⁺ T cells from seronegative, and treated HIV-infected individuals. The combination of TGF-β1 plus IL-23 induced the highest expression of CXCR5 in purified CD8⁺ T cells. These CXCR5⁺ CD8⁺ T cells also expressed a transcriptional and phenotypic profile similar to that of follicular CD4⁺ T cells, such as the upregulation of BCL6, inducible costimulator and CD40L, and downregulation of PRDM1. These cells responded in vitro to CXCL13 and had low expression of CCR7. In addition, after polyclonal stimulation, they produced IL-21, interferon-γ, and de novo perforin. However, in comparison with seronegative individuals, CD8⁺ T cells from HIV-infected patients had a lower response to TGF-β1/IL-23, a defect that was restored with the blockade of the programmed cell death 1 inhibitory receptor. Thus, TGF-β1 plus IL-23 induce follicular-like CXCR5⁺ CD8⁺ T cells in seronegative individuals, but in HIV-infected patients there is a limited response which could impair the generation of this cell population.

In vitro Infection of Primary Human Monocytes with HIV-1

Monocyte infection by HIV-1 is an important component of chronic HIV pathogenesis. Following infection by HIV-1, monocytes are able to cross the blood brain barrier and set up a viral reservoir in the central nervous system. Additionally, in the setting of chronic HIV-1 infection, monocytes can become activated either directly through HIV-1 infection or indirectly via HIV-1-mediated systemic immune activation. Currently, there are few studies looking at HIV-1 infection of primary human monocytes in vitro. Furthermore, detection of successful HIV-1 infection of monocytes can be laborious requiring an ELISA for p24 or assessing levels of HIV-1 mRNA or DNA. This protocol utilizes an HIV-1 strain expressing GFP to allow for easy quantification of HIV-1 infection by fluorescence-assisted cell sorting (FACS). By determining HIV-1 infection by FACS one can take advantage of its multiparametric nature allowing for the use of less cells and the ability to assess the expression of other markers on HIV-1⁺ and HIV-1^- cells in the same experiment. Additionally, this protocol could be modified to study HIV-1 infection of other cells including CD4⁺ T cells.

CCR5 editing by Staphylococcus aureus Cas9 in human primary CD4+ T cells and hematopoietic stem/progenitor cells promotes HIV-1 resistance and CD4+ T cell enrichment in humanized mice

BACKGROUND

The chemokine receptor CCR5, which belongs to the superfamily of G protein-coupled receptors, is the major co-receptor for HIV-1 entry. Individuals with a homozygous CCR5Δ32 mutation have a long lasting and increased resistance to HIV-1 infection. Therefore, CCR5 represents an optimal target for HIV-1/AIDS gene therapy. The CRISPR/Cas9 system has been developed as one of the most efficacious gene editing tools in mammalian cells and the small-sized version from Staphylococcus aureus (SaCas9) has an advantage of easier delivery compared to the most commonly used version from Streptococcus pyogenes Cas9 (SpCas9).

RESULTS

Here, we demonstrated that CCR5 could be specifically and efficiently edited by CRISPR/SaCas9 together with two sgRNAs, which were identified through a screening of 13 sgRNAs. Disruption of CCR5 expression by lentiviral vector-mediated CRISPR/SaCas9 led to increased resistance against HIV-1 infection in human primary CD4+ T cells. Moreover, humanized mice engrafted with CCR5-disrupted CD4+ T cells showed selective survival and enrichment when challenged with CCR5 (R5)-tropic HIV-1 in comparison to mock-treated CD4+ T cells. We also observed CCR5 could be targeted by CRISPR/SaCas9 in human CD34+ hematopoietic stem/progenitor cells without obvious differentiation deficiencies.

CONCLUSIONS

This work provides an alternative approach to disrupt human CCR5 by CRISPR/SaCas9 for a potential gene therapy strategy against HIV-1/AIDS.

Specific Activation In Vivo of HIV-1 by a Bromodomain Inhibitor from Monocytic Cells in Humanized Mice under Antiretroviral Therapy

Combination antiretroviral therapy (cART) effectively suppresses HIV-1 replication and enables HIV‑infected individuals to live long, productive lives. However, the persistence of HIV-1 reservoirs of both T and myeloid cells with latent or low-replicating HIV-1 in patients under cART makes HIV-1 infection an incurable disease. Recent studies have focused on the development of strategies to activate and purge these reservoirs. Bromodomain and extraterminal domain proteins (BETs) are epigenetic readers involved in modulating gene expression. Several bromodomain inhibitors (BETi) are reported to activate viral transcription in vitro in HIV-1 latency cell lines in a P-TEFb (CDK9/cyclin T1)-dependent manner. Little is known about BETi efficacy in activating HIV-1 reservoir cells under cART in vivo Here we report that a BETi (I-BET151) efficiently activated HIV-1 reservoirs under effective cART in humanized mice in vivo Interestingly, I-BET151 during suppressive cART in vivo activated HIV-1 gene expression only in monocytic cells and not in CD4⁺ T cells. We further demonstrate that BETi preferentially enhanced HIV-1 gene expression in monocytic cells rather than in T cells and that whereas CDK9 was involved in activating HIV-1 by I-BET151 in both monocytic and T cells, CDK2 enhanced HIV-1 transcription in monocytic cells but inhibited it in T cells. Our findings reveal a role for CDK2 in differential modulation of HIV-1 gene expression in myeloid cells and in T cells and provide a novel strategy to reactivate monocytic reservoirs with BETi during cART.IMPORTANCE Bromodomain inhibitors have been reported to activate HIV-1 transcription in vitro, but their effect on activation of HIV-1 reservoirs during cART in vivo is unclear. We found that BETi (I-BET151) treatment reactivated HIV-1 gene expression in humanized mice during suppressive cART. Interestingly, I-BET151 preferentially reactivated HIV-1 gene expression in monocytic cells, but not in CD4 T cells, in cART-treated mice. Furthermore, I-BET151 significantly increased HIV-1 transcription in monocytic cells, but not in HIV-1-infected CD4 T cells, via CDK2-dependent mechanisms. Our findings suggest that BETi can preferentially activate monocytic HIV-1 reservoir cells and that a combination of reservoir activation agents targeting different cell types and pathways is needed to achieve reactivation of different HIV-1 reservoir cells during cART.

Development of CAR-T cells for long-term eradication and surveillance of HIV-1 reservoir

Human immunodeficiency virus type 1 (HIV-1) reservoir is a pool of latently infected cells harboring replication-competent proviral DNA that limits antiretroviral therapy. Suppression of HIV-1 by combination antiretroviral therapy (cART) delays progression of the disease but does not eliminate the viral reservoir, necessitating lifetime daily administration of antiretroviral drugs. To achieve durable suppression of viremia without daily therapy, various strategies have been developed, including long-acting antiretroviral drugs (LA-ARVs), broadly neutralizing antibodies (bNAbs), and chimeric antigen receptor T (CAR-T) cells. Here, we summarize and discuss recent breakthroughs in CAR-T cell therapies toward the eradication of HIV-1 reservoir. Although substantial challenges exist, CAR-T cell technology may serve as a promising strategy toward HIV-1 functional cure.

Nanotechnology approaches to eradicating HIV reservoirs

The advent of combination antiretroviral therapy (cART) has transformed HIV-1 infection into a controllable chronic disease, but these therapies are incapable of eradicating the virus to bring about an HIV cure. Multiple strategies have been proposed and investigated to eradicate latent viral reservoirs from various biological sanctuaries. However, due to the complexity of HIV infection and latency maintenance, a single drug is unlikely to eliminate all HIV reservoirs and novel strategies may be needed to achieve better efficacy while limiting systemic toxicity. In this review, we describe HIV latency in cellular and anatomical reservoirs, and present an overview of current strategies for HIV cure with a focus on their challenges for clinical translation. Then we provide a summary of nanotechnology solutions that have been used to address challenges in HIV cure by delivering physicochemically diverse agents for combination therapy or targeting HIV reservoir sites. We also review nanocarrier-based gene delivery and immunotherapy used in cancer treatment but may have potential applications in HIV cure.

Poly-ICLC, a TLR3 Agonist, Induces Transient Innate Immune Responses in Patients With Treated HIV-Infection: A Randomized Double-Blinded Placebo Controlled Trial

Objective: Toll-like receptor-3 agonist Poly-ICLC has been known to activate immune cells and induce HIV replication in pre-clinical experiments. In this study we investigated if Poly-ICLC could be used for disrupting HIV latency while simultaneously enhancing innate immune responses.

Design: This was a randomized, placebo-controlled, double-blinded trial in aviremic, cART-treated HIV-infected subjects. Participants (n = 15) were randomized 3:1 to receive two consecutive daily doses of Poly-ICLC (1.4 mg subcutaneously) vs. placebo. Subjects were observed for adverse events, immune activation, and viral replication.

Methods: Besides primary outcomes of safety and tolerability, several longitudinal immune parameters were evaluated including immune cell phenotype and function via flowcytometry, ELISA, and transcriptional profiling. PCR assays for plasma HIV-1 RNA, CD4⁺ T cell-associated HIV-1 RNA, and proviral DNA were performed to measure HIV reservoirs and latency.

Results: Poly-ICLC was overall safe and well-tolerated. Poly-ICLC-related adverse events were Grade 1/2, with the exception of one Grade 3 neutropenia which was short-lived. Mild Injection site reactions were observed in nearly all participants in the Poly-ICLC arm. Transcriptional analyses revealed upregulation of innate immune pathways in PBMCs following Poly-ICLC treatment, including strong interferon signaling accompanied by transient increases in circulating IP-10 (CXCL10) levels. These responses generally peaked by 24–48 h after the first injection and returned to baseline by day 8. CD4⁺ T cell number and phenotype were unchanged, plasma viral control was maintained and no significant effect on HIV reservoirs was observed.

Conclusions: These finding suggest that Poly-ICLC could be safely used for inducing transient innate immune responses in treated HIV⁺ subjects indicating promise as an adjuvant for HIV therapeutic vaccines.

Trial Registration:www.ClinicalTrials.gov, identifier: NCT02071095.

Revisiting the 'sterilising cure' terminology: a call for more patient-centred perspectives on HIV cure-related research

The literature on HIV therapeutics research is rife with terminology associating 'sterilisation' with HIV cure. We find connotations of the word 'sterilising' problematic for the HIV cure research field. In this viewpoint, we review associations of sterilising with concepts of disinfection or cleansing, as well as coerced sterilisation. We discuss emerging findings from socio-behavioural research that show aversion from people living with HIV towards the 'sterilising cure' nomenclature. We call for more collaborations with people with HIV as partners to help define what would be a more acceptable terminology for describing an HIV cure.

HIV Subtype and Nef-Mediated Immune Evasion Function Correlate with Viral Reservoir Size in Early-Treated Individuals

The HIV accessory protein Nef modulates key immune evasion and pathogenic functions, and its encoding gene region exhibits high sequence diversity. Given the recent identification of early HIV-specific adaptive immune responses as novel correlates of HIV reservoir size, we hypothesized that viral factors that facilitate the evasion of such responses-namely, Nef genetic and functional diversity-might also influence reservoir establishment and/or persistence. We isolated baseline plasma HIV RNA-derived nef clones from 30 acute/early-infected individuals who participated in a clinical trial of early combination antiretroviral therapy (cART) (<6 months following infection) and assessed each Nef clone's ability to downregulate CD4 and human leukocyte antigen (HLA) class I in vitro We then explored the relationships between baseline clinical, immunological, and virological characteristics and the HIV reservoir size measured 48 weeks following initiation of suppressive cART (where the reservoir size was quantified in terms of the proviral DNA loads as well as the levels of replication-competent HIV in CD4⁺ T cells). Maximal within-host Nef-mediated downregulation of HLA, but not CD4, correlated positively with post-cART proviral DNA levels (Spearman's R = 0.61, P = 0.0004) and replication-competent reservoir sizes (Spearman's R = 0.36, P = 0.056) in univariable analyses. Furthermore, the Nef-mediated HLA downregulation function was retained in final multivariable models adjusting for established clinical and immunological correlates of reservoir size. Finally, HIV subtype B-infected persons (n = 25) harbored significantly larger viral reservoirs than non-subtype B-infected persons (2 infected with subtype CRF01_AE and 3 infected with subtype G). Our results highlight a potentially important role of viral factors-in particular, HIV subtype and accessory protein function-in modulating viral reservoir establishment and persistence.IMPORTANCE While combination antiretroviral therapies (cART) have transformed HIV infection into a chronic manageable condition, they do not act upon the latent HIV reservoir and are therefore not curative. As HIV cure or remission should be more readily achievable in individuals with smaller HIV reservoirs, achieving a deeper understanding of the clinical, immunological, and virological determinants of reservoir size is critical to eradication efforts. We performed a post hoc analysis of 30 participants of a clinical trial of early cART who had previously been assessed in detail for their clinical, immunological, and reservoir size characteristics. We observed that the HIV subtype and autologous Nef-mediated HLA downregulation function correlated with the viral reservoir size measured approximately 1 year post-cART initiation. Our findings highlight virological characteristics-both genetic and functional-as possible novel determinants of HIV reservoir establishment and persistence.

Population Pharmacokinetics and Pharmacodynamics of Disulfiram on Inducing Latent HIV-1 Transcription in a Phase IIb Trial

Disulfiram (DSF) was well tolerated and activated viral transcription (cell-associated unspliced (CA-US) and plasma human immunodeficiency virus (HIV) RNA) in a phase II dose-escalation trial in HIV+ antiretroviral therapy (ART)-suppressed participants. Here, we investigated whether exposure to DSF and its metabolites predicted these changes in HIV transcription. Participants were administered 500 (N = 10), 1,000 (N = 10), or 2,000 (N = 10) mg of DSF for 3 consecutive days. DSF and four metabolites were measured by ultraperformance liquid chromatography-tandem mass spectrometry. Changes in CA-US and plasma HIV RNA were quantified by polymerase chain reaction (PCR) and analyzed in NONMEM. A seven-compartment pharmacokinetic (PK) model demonstrated nonlinear elimination kinetics. The fitted median area under the curve values for 72 hours (AUC0-72 ) were 3,816, 8,386, and 22,331 mg*hour/L, respectively. Higher exposure predicted greater increases in CA-US (maximum effect (Emax ) = 78%, AUC50  = 1,600 μg*hour/L, P = 0.013) but not plasma HIV RNA. These results provide support for further development of DSF as an important drug for future HIV cure strategies.

Therapeutic HIV-1 vaccine: time for immunomodulation and combinatorial strategies

PURPOSE OF REVIEW

The purpose is to recall some of the key immunological elements that are at the crossroad and need to be combined for developing a potent therapeutic HIV-1 vaccine.

RECENT FINDINGS

Therapeutic vaccines and cytokines have been commonly used to enhance and/or recall preexisting HIV-1 specific cell-mediated immune responses aiming to suppress virus replication. While the vaccine is important to stimulate HIV-1 specific T-cell responses, the cytokine may support the expansion of the stimulated virus-specific T cells. Moreover, the current success of immune checkpoint blockers in cancer therapy render them very attractive to use in HIV-1 infected individuals, with the objective to preserve the function of HIV-specific T cells from exhaustion and target directly HIV-1 cell reservoir. More recently, the development of passive immunotherapy using broad neutralizing HIV antibodies (bNAbs) and their potential capacity to elicit innate or adaptive HIV-cellular responses, beyond their neutralizing activity, offers a new opportunity to improve the efficiency of therapeutic vaccine. These major advances provide the scientific basis for developing potent combinatorial interventions in HIV-1 infected patients.

SUMMARY

Major advances in our immunological understanding resulting from basic science and clinical trials studies have paved the way and established a solid platform to jump over the stumbling blocks that prevent the field from developing a therapeutic HIV-1 vaccine. It is time for immuno-modulation and combinatorial strategies towards HIV-1 eradication.

TRIM28 promotes HIV-1 latency by SUMOylating CDK9 and inhibiting P-TEFb

Comprehensively elucidating the molecular mechanisms of human immunodeficiency virus type 1 (HIV-1) latency is a priority to achieve a functional cure. As current 'shock' agents failed to efficiently reactivate the latent reservoir, it is important to discover new targets for developing more efficient latency-reversing agents (LRAs). Here, we found that TRIM28 potently suppresses HIV-1 expression by utilizing both SUMO E3 ligase activity and epigenetic adaptor function. Through global site-specific SUMO-MS study and serial SUMOylation assays, we identified that P-TEFb catalytic subunit CDK9 is significantly SUMOylated by TRIM28 with SUMO4. The Lys44, Lys56 and Lys68 residues on CDK9 are SUMOylated by TRIM28, which inhibits CDK9 kinase activity or prevents P-TEFb assembly by directly blocking the interaction between CDK9 and Cyclin T1, subsequently inhibits viral transcription and contributes to HIV-1 latency. The manipulation of TRIM28 and its consequent SUMOylation pathway could be the target for developing LRAs.

The human immunodeficiency virus-1, or HIV-1, infects certain human cells, including white blood cells. One reason the infection is incurable is because the virus can integrate its genetic information into its host, and essentially ‘sleep’ within the host cell, a process called latency. This helps to hide HIV-1 from the immune system and stops it getting destroyed.

Latency represents a critical challenge in treating and curing HIV-1. One proposed cure for HIV-1 involves ‘shocking’ the viruses out of latency so that they can be eliminated. Applying this so-called shock and kill approach means scientists need to understand more about how latency is maintained. Previous evidence shows that latency requires proteins known as histone deacetylases and histone methyltransferases. Certain gene-silencing proteins called transcription suppressors are also involved.

Ma et al. have now examined latent HIV-1 in several kinds of human cells grown in the laboratory. The cells were modified to make certain proteins at much lower levels than normal. The experiments showed that the loss of a protein called TRIM28 ‘wakes up’ latent HIV-1. TRIM28 attaches chemical marks called SUMOylations to gene regulators in the cell. These SUMOylations restrict the activity of HIV-1’s genes, which is important to maintain latency. Specifically, TRIM28 adds SUMOylations to a protein named CDK9 at three key positions.

Reducing the levels of TRIM28 made it easier to shock many HIV-1 in infected cells out of latency. With further investigation, targeting TRIM28 may one day be used to treat HIV-1 infection through a shock and kill method.

Acute HIV Infection in Youth: Protocol for the Adolescent Trials Network 147 (ATN147) Comprehensive Adolescent Research and Engagement Studies (CARES) Study

Background

Early treatment studies have shown that prompt treatment of HIV with combination antiretroviral therapy (cART) can limit the size of latent viral reservoirs, thereby providing clinical and public health benefits. Studies have demonstrated that adolescents have a greater capacity for immune reconstitution than adults. Nevertheless, adolescents who acquired HIV through sexual transmission have not been included in early treatment studies because of challenges in identification and adherence to cART.

Objective

This study aimed to identify and promptly treat with cART youth aged 12 to 24 years in Los Angeles and New Orleans who have acute, recent, or established HIV infection, as determined by Fiebig stages 1 to 6 determined by viral RNA polymerase chain reaction, p24 antigen presence, and HIV-1 antigen Western blot. The protocol recommends treatment on the day of diagnosis when feasible. Surveillance and dedicated behavioral strategies are used to retain them in care and optimize adherence. Through serial follow-up, HIV biomarkers and response to antiretroviral therapy (ART) are assessed. The study aims to assess viral dynamics, decay and persistence of viral reservoirs over time, and correlate these data with the duration of viral suppression.

Methods

A total of 72 youth (36 acutely infected and 36 treatment naïve controls) are enrolled across clinical sites using a current community-based strategy and direct referrals. Youth are prescribed ART according to the standard of care HIV-1 management guidelines and followed for a period of 2 years. Assessments are conducted at specific time points throughout these 2 years of follow-up for monitoring of adherence to ART, viral load, magnitude of HIV reservoirs, and presence of coinfections.

Results

The study began enrolling youth in July 2017 across study sites in Los Angeles and New Orleans. As of September 30, 2018, a total of 37 youth were enrolled, 12 with recently acquired, 16 with established HIV infection as determined by Fiebig staging, and 9 pending determination of Fiebig status. Recruitment and enrollment are ongoing.

Conclusions

We hypothesize that the size of the HIV reservoir and immune activation markers will be different across groups treated with cART, that is, those with acute or recent HIV infection and those with established infection. Adolescents treated early who are virally suppressed will have diminished HIV reservoirs than those with established infection. These youth may be potential candidates for a possible HIV vaccine and additional HIV remission intervention trials. Our study will inform future studies of viral remission strategies.

International Registered Report Identifier (IRRID)

DERR1-10.2196/10807

Epidemiological characteristics and clinical analysis of 97 AIDS patients

This study is to analyze clinical features of 97 AIDS patients received and treated in our hospital. Clinical data of 97 HIV-infected patients who were admitted between September 2004 and September 2018 were analyzed retrospectively. We found that all patients were in AIDS stage, CD4+ T lymphocytes counts were (210.56 ± 79.31)/µL. After the highly active antiretroviral therapy (HAART) regimens, CD4+ cell number is 315.21 ± 187.90, most patients before clinical symptoms are significantly improved. HIV infections were mainly through intravenous drug injection (51 cases, 52.58%) and sex contact (29 cases, 29.90%). In conclusion, the clinical manifestations of AIDS patients are various, and the main infection route is intravenous drug injection. Multiple measures should be taken to prevent and control HIV transmission, patients should undergo effective antiviral treatment, monitor and follow-up, so as to control opportunistic infection and virus replication.

Stability of plasma indices of inflammation/coagulation and homeostasis after fatty and non-fatty meals in treated people with HIV

OBJECTIVES

The relationship between lipid levels in plasma and inflammatory indices is complex and fatty meals alter plasma inflammatory markers in people with diabetes. There is interest in monitoring the effects of interventions on plasma inflammatory and coagulation elements in people with HIV, as they have been linked to risk for morbid outcomes and HIV persistence. Understanding the effects of feeding and time of specimen acquisition is important for the correct scheduling of clinical sampling.

METHODS

We examined the effects of feeding on plasma inflammatory, coagulation and homeostatic indices among 24 non-diabetic people with HIV, with controlled viraemia and on antiretroviral therapy after fasting and then 1, 3 and 6 hours after ingesting a fatty meal, and also approximately 1 week later after fasting and after an isocaloric non-fatty meal. Plasma levels of IL-6, IL-7, IP-10, sCD14, sCD163, sTNFrII and D-dimer were monitored by immunoassay.

RESULTS

Fasting levels of all markers obtained approximately 1 week apart were significantly correlated (P<0.001). Mild alterations in plasma concentrations of inflammatory markers were observed after feeding but geometric means varied more than 10% from baseline for only IL-6 and IL-7. Meal type was differentially associated with changes in plasma levels for IL-7 only. Antiretroviral treatment regimen, body mass index and changes in plasma triglyceride levels were not linked to post-feeding changes in these biomarkers.

CONCLUSIONS

These plasma inflammatory, coagulation and homeostatic indices are relatively stable at fasting and are only minimally affected by feeding or time of day. These findings will aid in the monitoring of inflammatory and homeostatic indices that may contribute to control of HIV expression and its persistence.

SLAMF7 Is a Critical Negative Regulator of IFN-α-Mediated CXCL10 Production in Chronic HIV Infection

Current advances in combined antiretroviral therapy have rendered HIV infection a chronic, manageable disease; however, the problem of persistent immune activation still remains despite treatment. The immune cell receptor SLAMF7 has been shown to be upregulated in diseases characterized by chronic immune activation. In this study, we studied the function of the SLAMF7 receptor in immune cells of HIV patients and the impacts of SLAMF7 signaling on peripheral immune activation. We observed increased frequencies of SLAMF7⁺ PBMCs in HIV⁺ individuals in a clinical phenotype-dependent manner, with discordant and long-term nonprogressor patients showing elevated SLAMF7 levels, and elite controllers showing levels comparable to healthy controls. We also noted that SLAMF7 was sensitive to IFN-⍺ stimulation, a factor elevated during HIV infection. Further studies revealed SLAMF7 to be a potent inhibitor of the monocyte-derived proinflammatory chemokine CXCL10 (IP-10) and other CXCR3 ligands, except in a subset of HIV⁺ patients termed SLAMF7 silent (SF7S). Studies utilizing small molecule inhibitors revealed that the mechanism of CXCL10 inhibition is independent of known SLAMF7 binding partners. Furthermore, we determined that SLAMF7 activation on monocytes is able to decrease their susceptibility to HIV-1 infection in vitro via downregulation of CCR5 and upregulation of the CCL3L1 chemokine. Finally, we discovered that neutrophils do not express SLAMF7, are CXCL10⁺ at baseline, are able to secrete CXCL10 in response to IFN-⍺ and LPS, and are nonresponsive to SLAMF7 signaling. These findings implicate the SLAMF7 receptor as an important regulator of IFN-⍺-driven innate immune responses during HIV infection.

HIV, HCV and HBV: A Review of Parallels and Differences

Elimination of the three blood-borne viruses-human immunodeficiency virus (HIV), hepatitis B (HBV) and hepatitis C (HCV)-as public health issues may be plausible in the near future. Spectacular advances have been made with the introduction of highly effective antiviral agents into clinical practice, and prevention strategies are available for all three infections. Effective disease control, laid out by WHO global strategies, is currently feasible for all three viruses. However, for worldwide elimination of these viruses, effective vaccines are required that are currently only available for HBV. In this review differences and parallels among HIV, HCV and HBV will be discussed with a focus on virologic and therapeutic issues, and prospects for the future of HBV will be presented.

Cancer immunotherapy of patients with HIV infection

Cancer immunotherapy with antibodies against immune checkpoints has made impressive advances in the last several years. The most relevant drugs target programmed cell death 1 (PD-1) expressed on T cells or its ligand, the programmed cell death ligand 1 (PD-L1), expressed on cancer cells, and cytotoxic T lymphocyte-associated protein 4 (CTLA-4). Unfortunately, cancer patients with HIV infection are usually excluded from cancer clinical trials, because there are concerns about the safety and the anti-tumoral activity of these novel therapies in patients with HIV infection. Several retrospective studies and some case reports now support the notion that antibodies against immune checkpoints are safe and active in cancer patients with HIV infection, but prospective data in these patients are lacking. In addition, signs of antiviral activity with increase in CD4 T cell counts, plasma viremia reduction or decrease in the viral reservoir have been reported in some of the patients treated, although no patient achieved a complete clearance of the viral reservoir. Here we briefly summarize all clinical cases reported in the literature, as well as ongoing clinical trials testing novel immunotherapy drugs in cancer patients with HIV infection.

Benzolactam-related compounds promote apoptosis of HIV-infected human cells via protein kinase C-induced HIV latency reversal

Latency-reversing agents (LRAs) are considered a potential strategy for curing cells of HIV-1 infection. Certain protein kinase C (PKC) activators have been previously reported to be LRAs because they can reverse HIV latency. In the present study, we examined the activities of a panel of benzolactam derivatives against cells latently infected with HIV. Using determination of p24 antigen in cell supernatants or altered intracellular GFP expression to measure HIV reactivation from latently infected cells along with a cytotoxicity assay, we found that some of the compounds exhibited latency-reversing activity, which was followed by enhanced release of HIV particles from the cells. One derivative, BL-V8-310, displayed activity in ACH-2 and J-Lat cells latently infected with HIV at a concentration of 10 nm or higher, which was superior to the activity of another highly active PKC activator, prostratin. These results were confirmed with peripheral blood cells from HIV-infected patients. We also found that these drugs up-regulate the expression of caspase 3 and enhance apoptosis specifically in latently HIV-infected cells. Moreover, combining BL-V8-310 with a bromodomain-containing 4 (BRD4) inhibitor, JQ1, not only enhanced HIV latency-reversing activity, but also reduced the effect on cytotoxic cytokine secretion from CD4⁺ T-cells induced by BL-V8-310 alone. Our results suggest that BL-V8-310 and its related benzolactam derivatives are potential LRA lead compounds that are effective in reversing HIV latency and reducing viral reservoirs in HIV-positive individuals with few adverse effects.

Phenotype, Polyfunctionality, and Antiviral Activity of in vitro Stimulated CD8+ T-Cells From HIV+ Subjects Who Initiated cART at Different Time-Points After Acute Infection

Since anti-HIV treatment cannot cure the infection, many strategies have been proposed to eradicate the viral reservoir, which still remains as a major challenge. The success of some of these strategies will rely on the ability of HIV-specific CD8+ T-cells (CD8TC) to clear reactivated infected cells. Here, we aimed to investigate the phenotype and function of in vitro expanded CD8TC obtained from HIV+ subjects on combination antiretroviral therapy (cART), either initiated earlier (median = 3 months postinfection, ET: Early treatment) or later (median = 20 months postinfection, DT: Delayed treatment) after infection. Peripheral blood mononuclear cells from 12 DT and 13 ET subjects were obtained and stimulated with Nef and Gag peptide pools plus IL-2 for 14 days. ELISPOT was performed pre- and post-expansion. CD8TC memory/effector phenotype, PD-1 expression, polyfunctionality (CD107a/b, IFN-γ, IL-2, CCL4 (MIP-1β), and/or TNF-α production) and antiviral activity were evaluated post-expansion. Magnitude of ELISPOT responses increased after expansion by 103 times, in both groups. Expanded cells were highly polyfunctional, regardless of time of cART initiation. The memory/effector phenotype distribution was sharply skewed toward an effector phenotype after expansion in both groups although ET subjects showed significantly higher proportions of stem-cell and central memory CD8TCs. PD-1 expression was clustered in HIV-specific effector memory CD8TCs, subset that also showed the highest proportion of cytokine-producing cells. Moreover, PD-1 expression directly correlated with CD8TC functionality. Expanded CD8TCs from DT and ET subjects were highly capable of mediating antiviral activity, measured by two different assays. Antiviral function directly correlated with the proportion of fully differentiated effector cells (viral inhibition assay) as well as with CD8TC polyfunctionality and PD-1 expression (VITAL assay). In sum, we show that, despite being dampened in subjects on cART, the HIV-specific CD8TC response could be selectively stimulated and expanded in vitro, presenting a high proportion of cells able to carry-out multiple effector functions. Timing of cART initiation had an impact on the memory/effector differentiation phenotype, most likely reflecting how different periods of antigen persistence affected immune function. Overall, these results have important implications for the design and evaluation of strategies aimed at modulating CD8TCs to achieve the HIV functional cure.

Mesenchymal stem cells are attracted to latent HIV-1-infected cells and enable virus reactivation via a non-canonical PI3K-NFκB signaling pathway

Persistence of latent HIV-1 in macrophages (MACs) and T-helper lymphocytes (THLs) remain a major therapeutic challenge. Currently available latency reversing agents (LRAs) are not very effective in vivo. Therefore, understanding of physiologic mechanisms that dictate HIV-1 latency/reactivation in reservoirs is clearly needed. Mesenchymal stromal/stem cells (MSCs) regulate the function of immune cells; however, their role in regulating virus production from latently-infected MACs & THLs is not known. We documented that exposure to MSCs or their conditioned media (MSC-CM) rapidly increased HIV-1 p24 production from the latently-infected U1 (MAC) & ACH2 (THL) cell lines. Exposure to MSCs also increased HIV-1 long terminal repeat (LTR) directed gene expression in the MAC and THL reporter lines, U937-VRX and J-Lat (9.2), respectively. MSCs exposed to CM from U1 cells (U1-CM) showed enhanced migratory ability towards latently-infected cells and retained their latency-reactivation potential. Molecular studies showed that MSC-mediated latency-reactivation was dependent upon both the phosphatidyl inositol-3-kinase (PI3K) and nuclear factor-κB (NFκB) signaling pathways. The pre-clinically tested inhibitors of PI3K (PX-866) and NFκB (CDDO-Me) suppressed MSC-mediated HIV-1 reactivation. Furthermore, coexposure to MSC-CM enhanced the latency-reactivation efficacy of the approved LRAs, vorinostat and panobinostat. Our findings on MSC-mediated latency-reactivation may provide novel strategies against persistent HIV-1 reservoirs.

Phylogenetic approach to recover integration dates of latent HIV sequences within-host

Given that HIV evolution and latent reservoir establishment occur continually within-host, and that latently infected cells can persist long-term, the HIV reservoir should comprise a genetically heterogeneous archive recapitulating within-host HIV evolution. However, this has yet to be conclusively demonstrated, in part due to the challenges of reconstructing within-host reservoir establishment dynamics over long timescales. We developed a phylogenetic framework to reconstruct the integration dates of individual latent HIV lineages. The framework first involves inference and rooting of a maximum-likelihood phylogeny relating plasma HIV RNA sequences serially sampled before the initiation of suppressive antiretroviral therapy, along with putative latent sequences sampled thereafter. A linear model relating root-to-tip distances of plasma HIV RNA sequences to their sampling dates is used to convert root-to-tip distances of putative latent lineages to their establishment (integration) dates. Reconstruction of the ages of putative latent sequences sampled from chronically HIV-infected individuals up to 10 y following initiation of suppressive therapy revealed a genetically heterogeneous reservoir that recapitulated HIV's within-host evolutionary history. Reservoir sequences were interspersed throughout multiple within-host lineages, with the oldest dating to >20 y before sampling; historic genetic bottleneck events were also recorded therein. Notably, plasma HIV RNA sequences isolated from a viremia blip in an individual receiving otherwise suppressive therapy were highly genetically diverse and spanned a 20-y age range, suggestive of spontaneous in vivo HIV reactivation from a large latently infected cell pool. Our framework for reservoir dating provides a potentially powerful addition to the HIV persistence research toolkit.

TLR3 agonist and CD40-targeting vaccination induces immune responses and reduces HIV-1 reservoirs

Activation of HIV-1 reservoirs and induction of anti-HIV-1 T cells are critical to control HIV-1 rebound after combined antiretroviral therapy (cART). Here we evaluated in humanized mice (hu-mice) with persistent HIV-1 infection the therapeutic effect of TLR3 agonist and a CD40-targeting HIV-1 vaccine, which consists of a string of 5 highly conserved CD4+ and CD8+ T cell epitope-rich regions of HIV-1 Gag, Nef, and Pol fused to the C-terminus of a recombinant anti-human CD40 antibody (αCD40.HIV5pep). We show that αCD40.HIV5pep vaccination coadministered with poly(I:C) adjuvant induced HIV-1-specific human CD8+ and CD4+ T cell responses in hu-mice. Interestingly, poly(I:C) treatment also reactivated HIV-1 reservoirs. When administrated in therapeutic settings in HIV-1-infected hu-mice under effective cART, αCD40.HIV5pep with poly(I:C) vaccination induced HIV-1-specific CD8+ T cells and reduced the level of cell-associated HIV-1 DNA (or HIV-1 reservoirs) in lymphoid tissues. Most strikingly, the vaccination significantly delayed HIV-1 rebound after cART cessation. In summary, the αCD40.HIV5pep with poly(I:C) vaccination approach both activates replication of HIV-1 reservoirs and enhances the anti-HIV-1 T cell response, leading to a reduced level of cell-associated HIV-1 DNA or reservoirs. Our proof-of-concept study has significant implication for the development of CD40-targeting HIV-1 vaccine to enhance anti-HIV-1 immunity and reduce HIV-1 reservoirs in patients with suppressive cART.

HIV

The benefits of combination antiretroviral therapy (cART) for HIV replication and transmission control have led to its universal recommendation. Many people living with HIV are, however, still undiagnosed or diagnosed late, especially in sub-Saharan Africa, where the HIV disease burden is highest. Further expansion in HIV treatment options, incorporating women-centred approaches, is essential to make individualised care a reality. With a longer life expectancy than before, people living with HIV are at an increased risk of developing non-AIDS comorbidities, such as cardiovascular diseases and cancers. Antiretroviral strategies are evolving towards a decrease in drug burden, and some two-drug combinations have proven efficacy for maintenance therapy. Investigational immune checkpoint inhibitors and broadly neutralising antibodies with effector functions have energised the HIV cure research field as the search for an effective vaccine continues. In this Seminar, we review advances and challenges relating to the goal of an AIDS-free world.

Developmental progress of CRISPR/Cas9 and its therapeutic applications for HIV-1 infection

The CRISPR/Cas9 system has been developed as a powerful tool for targeted gene editing. As a result of technical enhancements in recent years, this technology has become the method of choice for efficiently modifying targeted HIV-1 genome efficiently as part of HIV therapy. CRISPR can be modified to target specific sequences that Cas9 then cuts. In this article, we outline the development of the CRISPR/Cas9 system. We also show how this technology can be used for the prevention and treatment of HIV-1 infection. Optimistically, this technology promises to make a significant impact on the fight against HIV-1 in the future.

Sex Differences in HIV Infection: Mystique Versus Machismo

Biological sex is a determinant of both susceptibility to and pathogenesis of multiple infections, including HIV. These differences have effects on the spectrum of HIV disease from acquisition to eradication, with diverse mechanisms including distinct chromosomal complements, variation in microbiota composition, hormonal effects on transcriptional profiles, and expression of different immunoregulatory elements. With a comparative biology approach, these sex differences can be used to highlight protective and detrimental immune activation pathways, to identify strategies for effective prevention, treatment, and curative interventions.

Spontaneous reactivation of latent HIV-1 promoters is linked to the cell cycle as revealed by a genetic-insulators-containing dual-fluorescence HIV-1-based vector

Long-lived latently HIV-1-infected cells represent a barrier to cure. We developed a dual-fluorescence HIV-1-based vector containing a pair of genetic insulators flanking a constitutive fluorescent reporter gene to study HIV-1 latency. The protective effects of these genetic insulators are demonstrated through long-term (up to 394 days) stable fluorescence profiles in transduced SUP-T1 cells. Analysis of 1,941 vector integration sites confirmed reproduction of HIV-1 integration patterns. We sorted monoclonal cells representing latent HIV-1 infections and found that both vector integration sites and integrity of the vector genomes influence the reactivation potentials of latent HIV-1 promoters. Interestingly, some latent monoclonal cells exhibited a small cell subpopulation with a spontaneously reactivated HIV-1 promoter. Higher expression levels of genes involved in cell cycle progression are observed in these cell subpopulations compared to their counterparts with HIV-1 promoters that remained latent. Consistently, larger fractions of spontaneously reactivated cells are in the S and G2 phases of the cell cycle. Furthermore, genistein and nocodazole treatments of these cell clones, which halted cells in the G2 phase, resulted in a 1.4–2.9-fold increase in spontaneous reactivation. Taken together, our HIV-1 latency model reveals that the spontaneous reactivation of latent HIV-1 promoters is linked to the cell cycle.

Systemic DPP4 activity is reduced during primary HIV-1 infection and is associated with intestinal RORC+ CD4+ cell levels: a surrogate marker candidate of HIV-induced intestinal damage

INTRODUCTION

Combined anti-retroviral therapy (cART) transformed HIV-1 from a deadly disease into a chronic infection, but does not cure HIV infection. It also does not fully restore HIV-induced gut damage unless administered extremely early after infection. Additional biomarkers are needed to evaluate the capacity of therapies aimed at HIV remission/cure to restore HIV-induced intestinal immune damage and limit chronic inflammation. Herein, we aimed to identify a systemic surrogate marker whose levels would reflect gut immune damage such as intestinal Th17 cell loss starting from primary HIV-1 infection.

METHODS

Biomarker discovery approaches were performed in four independent cohorts, covering HIV-1 primary and chronic infection in 496 naïve or cART-treated patients (Amsterdam cohort (ACS), ANRS PRIMO, COPANA and CODEX cohorts). The concentration and activity of soluble Dipeptidylpeptidase 4 (sDPP4) were quantified in the blood from these patients, including pre- and post-infection samples in the ACS cohort. For quantification of DPP4 in the gut, we utilized two non-human primate models, representing pathogenic (macaque) and non-pathogenic (African green monkey) SIV infection. Four gut compartments were analysed in each animal model (ileum, jejunum, colon and rectum) for quantification of DPP4, RORC and TBX21 gene expression in sorted CD4+ cells. To analyse if sDPP4 levels increase when Th17 cells were restored, we quantified sDPP4 in plasma from SIV-infected macaques treated with IL-21.

RESULTS

We showed that sDPP4 levels were strongly decreased in primary HIV-1 infection. Strikingly, sDPP4 levels in primary HIV-1 infection predicted time to AIDS. They were not increased by cART in chronic HIV-1 infection (median 36 months on cART). In the gut of SIV-infected non-human primates, DPP4 mRNA was higher in CD4+ than CD4- leucocytes. DPP4 specifically correlated with RORC expression, a Th17 marker, in CD4+ cells from the intestine. We further demonstrated that sDPP4 activity levels were increased in animals treated with IL-21 and that this increase was associated with restoration of the Th17 compartment and reduced inflammation. Furthermore, DPP4 mRNA levels in small intestine CD4+ cells positively correlated with circulating DPP4 activity.

CONCLUSION

These data provide evidence that blood sDPP4 levels could be useful as a correlate for HIV-induced intestinal damage.

Core-shell nanoparticles for targeted and combination antiretroviral activity in gut-homing T cells

A major sanctuary site for HIV infection is the gut-associated lymphoid tissue (GALT). The α4β7 integrin gut homing receptor is a promising therapeutic target for the virus reservoir because it leads to migration of infected cells to the GALT and facilitates HIV infection. Here, we developed a core-shell nanoparticle incorporating the α4β7 monoclonal antibody (mAb) as a dual-functional ligand for selectively targeting a protease inhibitor (PI) to gut-homing T cells in the GALT while simultaneously blocking HIV infection. Our nanoparticles significantly reduced cytotoxicity of the PI and enhanced its in vitro antiviral activity in combination with α4β7 mAb. We demonstrate targeting function of our nanocarriers in a human T cell line and primary cells isolated from macaque ileum, and observed higher in vivo biodistribution to the murine small intestines where they accumulate in α4β7+ cells. Our LCNP shows the potential to co-deliver ARVs and mAbs for eradicating HIV reservoirs.

Inducing CCR5Δ32/Δ32 Homozygotes in the Human Jurkat CD4+ Cell Line and Primary CD4+ Cells by CRISPR-Cas9 Genome-Editing Technology

C-C chemokine receptor type 5 (CCR5) is the main co-receptor for HIV entry into the target CD4+ cells, and homozygous CCR5Δ32/Δ32 cells are resistant to CCR5-tropic HIV infection. However, the CCR5Δ32/Δ32 homozygous donors in populations are rare. Here we developed a simple approach to induce CCR5Δ32/Δ32 homozygotes through CRISPR-Cas9 genome-editing technology. Designing a pair of single-guide RNA targeting the flank region of the CCR5Δ32 mutation locus, we applied the CRISPR-Cas9 and lentiviral packaging system to successfully convert wild-type CCR5 into CCR5Δ32/Δ32 homozygotes in the human Jurkat CD4+ cell line and primary CD4+ cells, exactly the same as the naturally occurring CCR5Δ32/Δ32 mutation. The successful rate is up to 20% in Jurkat cells but less in primary CD4+ cells. The modified CCR5Δ32/Δ32 CD4+ cells are resistant to CCR5-tropic HIV infection. Whole-genome sequencing revealed no apparent off-target sites. This approach has the promise to promote HIV/AIDS therapy from the only cured unique Berlin patient to a routine autologous cell-based therapy.

Humanized Mice Engrafted With Human HSC Only or HSC and Thymus Support Comparable HIV-1 Replication, Immunopathology, and Responses to ART and Immune Therapy

Immunodeficient mice reconstituted with human immune tissues and cells (humanized mice) are relevant and robust models for the study of HIV-1 infection, immunopathogenesis, and therapy. In this study, we performed a comprehensive comparison of human immune reconstitution and HIV-1 infection, immunopathogenesis and therapy between immunodeficient NOD/Rag2-/-/γc-/- (NRG) mice transplanted with human HSCs (NRG-hu HSC) and mice transplanted with HSCs and thymus fragments (NRG-hu Thy/HSC) from the same donors. We found that similar human lymphoid and myeloid lineages were reconstituted in NRG-hu HSC and NRG-hu Thy/HSC mice, with human T cells more predominantly reconstituted in NRG-hu Thy/HSC mice, while NRG-hu HSC mice supported more human B cells and myeloid cells reconstitution. HIV-1 replicated similarly and induced similar T cell depletion, immune activation, and dysfunction in NRG-hu HSC and NRG-hu Thy/HSC mice. Moreover, combined antiretroviral therapy (cART) inhibited HIV-1 replication efficiently with similar persistent HIV-1 reservoirs in both models. Finally, we found that blocking type-I interferon signaling under cART treatment transiently activated HIV-1 reservoirs, enhanced T cell recovery and reduced HIV-1 reservoirs in both HIV-1 infected NRG-hu HSC and NRG-hu Thy/HSC mice. In summary, we report that NRG-hu Thy/HSC and NRG-hu HSC mice support similar HIV-1 infection and similar HIV-1 immunopathology; and HIV-1 replication responds similarly to cART and IFNAR blockade therapies. The NRG-hu HSC mouse model reconstituted with human HSC only is sufficient for the study of HIV-1 infection, pathogenesis, and therapy.

Frontline Science: Plasma and immunoglobulin G galactosylation associate with HIV persistence during antiretroviral therapy

Global antibody glycosylation is dynamic and plays critical roles in shaping different immunological outcomes and direct antibody functionality during HIV infection. However, the relevance of global antibody or plasma glycosylation patterns to HIV persistence after antiretroviral therapy (ART) has not been characterized. First, we compared glycomes of total plasma and isolated immunoglobulin G (IgG) from HIV+ ART-suppressed, HIV+ viremic, and HIV-negative individuals. Second, in ART-suppressed individuals, we examined the associations between glycomes and (1) levels of cell-associated HIV DNA and RNA in PBMCs and isolated CD4+ T cells, (2) CD4 count and CD4%, and (3) expression of CD4+ T-cell activation markers. HIV infection is associated with persistent alterations in the IgG glycome including decreased levels of disialylated glycans, which is associated with a lower anti-inflammatory activity, and increased levels of fucosylated glycans, which is associated with lower antibody-dependent cell-mediated cytotoxicity (ADCC). We also show that levels of certain mono- and digalactosylated nonfucosylated glycomic traits (A2G1, A2G2, and A2BG2), which have been reported to be associated with higher ADCC and higher anti-inflammatory activities, exhibit significant negative correlations with levels of cell-associated total HIV DNA and HIV RNA in ART-suppressed individuals. Finally, levels of certain circulating anti-inflammatory glycans are associated with higher levels of CD4 T cells and lower levels of T-cell activation. Our findings represent the first proof-of-concept evidence that glycomic alterations, known to be associated with differential states of inflammation and ADCC activities, are also associated with levels of HIV persistence in the setting of ART suppression.

Exosomal Tat protein activates latent HIV-1 in primary, resting CD4+ T lymphocytes

Replication competent HIV-1 persists in a subpopulation of CD4+ T lymphocytes despite prolonged antiretroviral treatment. This residual reservoir of infected cells harbors transcriptionally silent provirus capable of reigniting productive infection upon discontinuation of antiretroviral therapy. Certain classes of drugs can activate latent virus but not at levels that lead to reductions in HIV-1 reservoir size in vivo. Here, we show the utility of CD4+ receptor targeting exosomes as an HIV-1 latency reversal agent (LRA). We engineered human cellular exosomes to express HIV-1 Tat, a protein that is a potent transactivator of viral transcription. Preparations of exosomal Tat-activated HIV-1 in primary, resting CD4+ T lymphocytes isolated from antiretroviral-treated individuals with prolonged periods of viral suppression and led to the production of replication competent HIV-1. Furthermore, exosomal Tat increased the potency of selected LRA by over 30-fold in terms of HIV-1 mRNA expression, thereby establishing it as a potentially new class of biologic product with possible combinatorial utility in targeting latent HIV-1.

Strategies for the cure of HIV infection

The disadvantages of the long-term administration of antiretroviral therapy as well as the huge number of affected persons have placed the cure of HIV as a primary goal of Public Health. HIV may persist in the organism by at least four mechanisms: a latently infected cellular reservoir, the persistent replication of HIV in spite of ART, anatomic sanctuaries, and the immune dysfunction. Several strategies directed against these mechanisms have been developed. With all this, a complete eradication of HIV has been achieved in a patient using the transplantation of haemopoietic stem cells that were resistant to HIV-infection, and there are examples of functional cure either spontaneously (elite controllers) or after antiretroviral therapy (post-treatment controllers). However, no strategies have been successful in reducing the reservoir size, nor in achieving constant, uniform remissions. The failure of isolated strategies makes it likely that the combination of several of them may be the future solution.

Efficient generation of antigen-specific CTLs by the BAFF-activated human B Lymphocytes as APCs: a novel approach for immunotherapy

Efficient antigen presentation is indispensable for cytotoxic T lymphocyte (CTL)-mediated immunotherapy. B-lymphocytes propagated with CD40L have been developed as antigen-presenting cells (APCs), but this capacity needs further optimization. Here, we aimed to expand human B-lymphocytes on a large scale while maintaining their antigen-presenting ability by using both CD40L and B-cell activating factor (BAFF). The addition of BAFF enhanced the expansion efficiency and prolonged the culture time without causing apoptosis of the expanded B-cells. This method thus provided an almost unlimited source of cellular adjuvant to achieve sufficient expansion of CTLs in cases where several rounds of stimulation are required. We also showed that the addition of BAFF significantly enhanced the expression of major costimulatory molecules, CD80 and CD86. Subsequently, the antigen-presenting ability of the B-lymphocytes also increased. Consequently, these B-lymphocytes showed robust CTL responses to inhibit tumor growth after tumor-specific peptide pulses. A similar method induced potent antigen-specific CTL responses, which effectively eradicated human immunodeficiency virus type 1 (HIV-1) latency in CD4 T-lymphocytes isolated from patients receiving suppressive anti-retroviral therapy (ART). Together, our findings indicate that potent antigen-specific CTLs can be generated using BAFF-activated B-lymphocytes as APCs ex vivo. This approach can be applied for CTL-mediated immunotherapy in patients with cancers or chronic viral infections.

Perspectives for immunotherapy: which applications might achieve an HIV functional cure?

The major advances achieved in devising successful combined antiretroviral therapy (cART) have enabled the sustained control of HIV replication. However, this is associated with costly lifelong treatment, partial immune restoration, chronic inflammation and persistent viral reservoirs. In this context, new therapeutic strategies deserve investigation as adjuncts to cART so as to potentiate immune responses that are capable of completely containing HIV pathogenicity, particularly if cART is discontinued. This may seem a dauntingly high hurdle given the results to date. This review outlines the key research efforts that have recently resurrected immunotherapeutic options, and some of the approaches tested to date. These areas include promising cytokines or vaccine strategies, using different viral or non-viral vectors based on polyvalent “mosaic” antigens and highly conserved HIV envelope peptides, broadly neutralizing antibodies or new properties of antibodies to improve the control of immune system homeostasis. These novel immunotherapeutic strategies appear promising per se, or in combination with TLR-agonists in order to bypass the complexity of the interplay between immune activation, massive CD4⁺ T-cell loss and viral persistence.

"cART intensification by the HIV-1 Tat B clade vaccine: progress to phase III efficacy studies"

INTRODUCTION

In spite of its success at suppressing HIV replication, combination antiretroviral therapy (cART) only partially reduces immune dysregulation and loss of immune functions. These cART-unmet needs appear to be due to persistent virus replication and cell-to-cell transmission in reservoirs, and are causes of increased patients' morbidity and mortality. Up to now, therapeutic interventions aimed at cART-intensification by attacking the virus reservoir have failed.

AREAS COVERED

We briefly review the rationale and clinical development of Tat therapeutic vaccine in cART-treated subjects in Italy and South Africa (SA). Vaccination with clade-B Tat induced cross-clade neutralizing antibodies, immune restoration, including CD4⁺ T cell increase particularly in low immunological responders, and reduction of proviral DNA. Phase III efficacy trials in SA are planned both in adult and pediatric populations.

EXPERT COMMENTARY

We propose the Tat therapeutic vaccine as a pathogenesis-driven intervention that effectively intensifies cART and may lead to a functional cure and provide new perspectives for prevention and virus eradication strategies.

Novel mechanisms to inhibit HIV reservoir seeding using Jak inhibitors

Despite advances in the treatment of HIV infection with ART, elucidating strategies to overcome HIV persistence, including blockade of viral reservoir establishment, maintenance, and expansion, remains a challenge. T cell homeostasis is a major driver of HIV persistence. Cytokines involved in regulating homeostasis of memory T cells, the major hub of the HIV reservoir, trigger the Jak-STAT pathway. We evaluated the ability of tofacitinib and ruxolitinib, two FDA-approved Jak inhibitors, to block seeding and maintenance of the HIV reservoir in vitro. We provide direct demonstration for involvement of the Jak-STAT pathway in HIV persistence in vivo, ex vivo, and in vitro; pSTAT5 strongly correlates with increased levels of integrated viral DNA in vivo, and in vitro Jak inhibitors reduce the frequency of CD4+ T cells harboring integrated HIV DNA. We show that Jak inhibitors block viral production from infected cells, inhibit γ-C receptor cytokine (IL-15)-induced viral reactivation from latent stores thereby preventing transmission of infectious particles to bystander activated T cells. These results show that dysregulation of the Jak-STAT pathway is associated with viral persistence in vivo, and that Jak inhibitors target key events downstream of γ-C cytokine (IL-2, IL-7 and IL-15) ligation to their receptors, impacting the magnitude of the HIV reservoir in all memory CD4 T cell subsets in vitro and ex vivo. Jak inhibitors represent a therapeutic modality to prevent key events of T cell activation that regulate HIV persistence and together, specific, potent blockade of these events may be integrated to future curative strategies.

Regulatory T Cells Contribute to HIV-1 Reservoir Persistence in CD4+ T Cells Through Cyclic Adenosine Monophosphate-Dependent Mechanisms in Humanized Mice In Vivo

Background

Regulatory T cells (Tregs) suppress T-cell immune activation and human immunodeficiency virus type 1 (HIV-1) replication, but the role of Tregs in HIV-1 reservoir persistence is poorly defined.

Methods

Tregs were depleted by denileukin diftitox in humanized mice with chronic HIV-1 infection. Viral replication in lineage cells was determined by p24 expression. Levels of HIV-1 RNA and DNA in human cells, as well as replication-competent-virus-producing cells, were measured to quantified viral replication and reservoirs.

Results

Treg depletion resulted in a blip of HIV-1 replication in T cells but not in myeloid cells. The major activated reservoir cells were memory CD4+ T cells in vivo. Interestingly, the transient activation of viral replication led to HIV-1 reservoir reduction after viremia resuppression, as indicated by the quantity of HIV-1 DNA and replication-competent-virus-producing cells. Furthermore, we demonstrated that Tregs use cyclic adenosine monophosphate (cAMP)-dependent protein kinase A pathway to inhibit HIV-1 activation and replication in resting conventional T cells in vitro.

Conclusion

Tregs suppress HIV-1 replication in T cells and contribute to HIV-1 reservoir persistence. cAMP produced in Tregs is involved in their suppression of viral gene activation and expression. Treg depletion combined with combination antiretroviral therapy provides a novel strategy for HIV-1 cure.

HIV-1 infection of microglial cells in a reconstituted humanized mouse model and identification of compounds that selectively reverse HIV latency

Most studies of HIV latency focus on the peripheral population of resting memory T cells, but the brain also contains a distinct reservoir of HIV-infected cells in microglia, perivascular macrophages, and astrocytes. Studying HIV in the brain has been challenging, since live cells are difficult to recover from autopsy samples and primate models of SIV infection utilize viruses that are more myeloid-tropic than HIV due to the expression of Vpx. Development of a realistic small animal model would greatly advance studies of this important reservoir and permit definitive studies of HIV latency. When radiation or busulfan-conditioned, immune-deficient NSG mice are transplanted with human hematopoietic stem cells, human cells from the bone marrow enter the brain and differentiate to express microglia-specific markers. After infection with replication competent HIV, virus was detected in these bone marrow-derived human microglia. Studies of HIV latency in this model would be greatly enhanced by the development of compounds that can selectively reverse HIV latency in microglial cells. Our studies have identified members of the CoREST repression complex as key regulators of HIV latency in microglia in both rat and human microglial cell lines. The monoamine oxidase (MAO) and potential CoREST inhibitor, phenelzine, which is brain penetrant, was able to stimulate HIV production in human microglial cell lines and human glial cells recovered from the brains of HIV-infected humanized mice. The humanized mice we have developed therefore show great promise as a model system for the development of strategies aimed at defining and reducing the CNS reservoir.