Lack of Decay of HIV-1 in Gut-Associated Lymphoid Tissue Reservoirs in Maximally Suppressed Individuals

Viral Persistence in the Gut-Associated Lymphoid Tissue and Barriers to HIV Cure

More than 40 years after the first reported cases of what then became known as acquired immunodeficiency syndrome (AIDS), tremendous progress has been achieved in transforming the disease from almost universally fatal to a chronic manageable condition. Nonetheless, the efforts to find a preventative vaccine or a cure for the underlying infection with Human Immunodeficiency Virus (HIV) remain largely unsuccessful. Many challenges intrinsic to the virus characteristics and host response need to be overcome for either goal to be achieved. This article will review the obstacles to an effective HIV cure, specifically the steps involved in the generation of HIV latency, focusing on the role of the gut-associated lymphoid tissue, which has received less attention compared with the peripheral blood, despite being the largest repository of lymphoid tissue in the human body, and a large site for HIV persistence.

Enhancing HIV-1 Neutralization by Increasing the Local Concentration of Membrane-Proximal External Region-Directed Broadly Neutralizing Antibodies

Broadly neutralizing antibodies (bNAbs) against the membrane-proximal external region (MPER) of the gp41 component of the human immunodeficiency virus type 1 (HIV-1) envelope (Env) are characterized by long, hydrophobic, heavy chain complementarity-determining region 3s (HCDR3s) that interact with the MPER and some viral membrane lipids to achieve increased local concentrations. Here, we show that increasing the local concentration of MPER-directed bNAbs at the cell surface via binding to the high-affinity Fc receptor FcγRI potentiates their ability to prevent viral entry in a manner analogous to the previously reported observation wherein the lipid-binding activity of MPER bNAbs increases their concentration at the viral surface membrane. However, binding of MPER-directed bNAb 10E8 to FcγRI abolishes the neutralization synergy that is seen with the N-heptad repeat (NHR)-targeting antibody D5_AR and NHR-targeting small molecule enfuvirtide (T20), possibly due to decreased accessibility of the NHR in the FcγRI-10E8-MPER complex. Taken together, our results suggest that lipid-binding activity and FcγRI-mediated potentiation function in concert to improve the potency of MPER-directed bNAbs by increasing their local concentration near the site of viral fusion. Therefore, lipid binding may not be a strict requirement for potent neutralization by MPER-targeting bNAbs, as alternative methods can achieve similar increases in local concentrations while avoiding potential liabilities associated with immunologic host tolerance. IMPORTANCE The trimeric glycoprotein Env, the only viral protein expressed on the surface of HIV-1, is the target of broadly neutralizing antibodies and the focus of most vaccine development efforts. Broadly neutralizing antibodies targeting the membrane proximal external region (MPER) of Env show lipid-binding characteristics, and modulating this interaction affects neutralization. In this study, we tested the neutralization potencies of variants of the MPER-targeting antibody 10E8 with different viral-membrane-binding and host FcγRI-binding capabilities. Our results suggest that binding to both lipid and FcγRI improves the neutralization potency of MPER-directed antibodies by concentrating the antibodies at sites of viral fusion. As such, lipid binding may not be uniquely required for MPER-targeting broadly neutralizing antibodies, as alternative methods to increase local concentration can achieve similar improvements in potency.

Genotypic and Phenotypic Diversity of the Replication-Competent HIV Reservoir in Treated Patients

In HIV infection, viral rebound after treatment discontinuation is considered to originate predominantly from viral genomes integrated in resting CD4⁺ T lymphocytes. Replication-competent proviral genomes represent a minority of the total HIV DNA. While the quantification of the HIV reservoir has been extensively studied, the diversity of genomes that compose the reservoir was less explored. Here, we measured the genotypic and phenotypic diversity in eight patients with different treatment histories. Between 4 and 14 (mean, 8) individual viral isolates per patient were obtained using a virus outgrowth assay, and their near-full-length genomes were sequenced. The mean pairwise distance (MPD) observed in different patients correlated with the time before undetectable viremia was achieved (r = 0.864, P = 0.0194), suggesting that the complexity of the replication-competent reservoir mirrors that present at treatment initiation. No correlation was instead observed between MPD and the duration of successful treatment (mean, 8 years; range, 2 to 21 years). For 5 of the 8 patients, genotypically identical viral isolates were observed in independent wells, suggesting clonal expansion of infected cells. Identical viruses represented between 25 and 60% of the isolates (mean, 48%). The proportion of identical viral isolates correlated with the duration of treatment (r = 0.822, P = 0.0190), suggesting progressive clonal expansion of infected cells during ART. A broader range of infectivity was also observed among isolates from patients with delayed viremia control (r = 0.79, P = 0.025). This work unveiled differences in the genotypic and phenotypic features of the replication-competent reservoir from treated patients and suggests that delaying treatment results in increased diversity of the reservoir.

IMPORTANCE In HIV-infected and effectively treated individuals, integrated proviral genomes may persist for decades. The vast majority of the genomes, however, are defective, and only the replication-competent fraction represents a threat of viral reemergence. The quantification of the reservoir has been thoroughly explored, while the diversity of the genomes has been insufficiently studied. Its characterization, however, is relevant for the design of strategies aiming the reduction of the reservoir. Here, we explored the replication-competent near-full-length HIV genomes of eight patients who experienced differences in the delay before viremia control and in treatment duration. We found that delayed effective treatment was associated with increased genetic diversity of the reservoir. The duration of treatment did not impact the diversity but was associated with higher frequency of clonally expanded sequences. Thus, early treatment initiation has the double advantage of reducing both the size and the diversity of the reservoir.

First-in-human immunoPET imaging of HIV-1 infection using 89Zr-labeled VRC01 broadly neutralizing antibody

A major obstacle to achieving long-term antiretroviral (ART) free remission or functional cure of HIV infection is the presence of persistently infected cells that establish a long-lived viral reservoir. HIV largely resides in anatomical regions that are inaccessible to routine sampling, however, and non-invasive methods to understand the longitudinal tissue-wide burden of HIV persistence are urgently needed. Positron emission tomography (PET) imaging is a promising strategy to identify and characterize the tissue-wide burden of HIV. Here, we assess the efficacy of using immunoPET imaging to characterize HIV reservoirs and identify anatomical foci of persistent viral transcriptional activity using a radiolabeled HIV Env-specific broadly neutralizing antibody, ⁸⁹Zr-VRC01, in HIV-infected individuals with detectable viremia and on suppressive ART compared to uninfected controls (NCT03729752). We also assess the relationship between PET tracer uptake in tissues and timing of ART initiation and direct HIV protein expression in CD4 T cells obtained from lymph node biopsies. We observe significant increases in ⁸⁹Zr-VRC01 uptake in various tissues (including lymph nodes and gut) in HIV-infected individuals with detectable viremia (N = 5) and on suppressive ART (N = 5) compared to uninfected controls (N = 5). Importantly, PET tracer uptake in inguinal lymph nodes in viremic and ART-suppressed participants significantly and positively correlates with HIV protein expression measured directly in tissue. Our strategy may allow non-invasive longitudinal characterization of residual HIV infection and lays the framework for the development of immunoPET imaging in a variety of other infectious diseases.

Differential localization and limited cytotoxic potential of duodenal CD8+ T cells

The duodenum is a major site of HIV persistence during suppressive antiretroviral therapy despite harboring abundant tissue-resident memory (Trm) CD8⁺ T cells. The role of duodenal Trm CD8⁺ T cells in viral control is still not well defined. We examined the spatial localization, phenotype, and function of CD8⁺ T cells in the human duodenal tissue from people living with HIV (PLHIV) and healthy controls. We found that Trm (CD69⁺CD103^hi) cells were the predominant CD8⁺ T cell population in the duodenum. Immunofluorescence imaging of the duodenal tissue revealed that CD103⁺CD8⁺ T cells were localized in the intraepithelial region, while CD103^–CD8⁺ T cells and CD4⁺ T cells were mostly localized in the lamina propria (LP). Furthermore, HIV-specific CD8⁺ T cells were enriched in the CD69⁺CD103^–/lo population. However, the duodenal HIV-specific CD8⁺ Trm cells rarely expressed canonical molecules for potent cytolytic function (perforin and granzyme B) but were more polyfunctional than those from peripheral blood. Taken together, our results show that duodenal CD8⁺ Trm cells possess limited perforin-mediated cytolytic potential and are spatially separated from HIV-susceptible LP CD4⁺ T cells. This could contribute to HIV persistence in the duodenum and provides critical information for the design of cure therapies.

HIV-1-Specific CAR-T Cells With Cell-Intrinsic PD-1 Checkpoint Blockade Enhance Anti-HIV Efficacy in vivo

Adoptive cellular immunotherapy therapy using broadly neutralizing antibody-based chimeric antigen receptor-T cells (bNAb-based CAR-T) has shown great potency and safety for the functional cure of HIV. The efficacy of bNAb-based CAR-T cells could be compromised by adaptive resistance during HIV chronic infection according to the phenomenon that cellular exhaustion was observed in endogenous cytotoxic T-lymphocytes (CTLs) along with upregulated expression of PD−1. Here, we created HIV-specific CAR-T cells using human peripheral blood mononuclear cells (PBMCs) and a 3BNC117-DNR CAR (3BD CAR) construct that enables the expression of PD-1 dominant negative receptor (DNR) and the single-chain variable fragment of the HIV-1-specific broadly neutralizing antibody 3BNC117 to target native HIV envelope glycoprotein (Env). Compared with HIV CAR expression alone, 3BD CAR-T cells displayed potent lytic and functional responses to Env-expressing cell lines and HIV-infected CD4⁺ T cells. Moreover, 3BD CAR-T cells can kill HIV-latently-infected cell lines, which are reactivated by the secretory cytokines of effector cells followed by contact with initial HIV-expressing fraction. Furthermore, bioluminescence imaging indicated that 3BD CAR-T cells displayed superior anti-HIV function in an HIV NCG mouse model of transplanting Env⁺/PD-L1⁺ cells (LEL6). These studies suggested that our proposed combinational strategy of HIV CAR-T therapy with PD-1 blockade therapy is feasible and potent, making it a promising therapeutic candidate for HIV functional cure.

CD9 and ITGA3 are regulated during HIV-1 infection in macrophages to support viral replication

Monocytes/macrophages are important target cells for HIV-1. Here, we investigated whether HIV-1 induces changes in the macrophage gene expression profile to support viral replication. We observed that the macrophage gene expression profiles dramatically changed upon HIV-1 infection. The majority of the HIV-1 regulated genes were also differentially expressed in M2a macrophages. The biological functions associated with the HIV-1 induced gene expression profile in macrophages were mainly related to inflammatory responses. CD9 and ITGA3 were among the top genes upregulated upon HIV-1 infection. We showed that these genes support viral replication and that downregulation of these genes decreased HIV-1 replication in macrophages. Here we showed that HIV-1 infection of macrophages induces a gene expression profile that may dampen inflammatory responses. CD9 and ITGA3 were among the top genes regulated by HIV-1 and were shown to support viral production most likely at the level of viral budding and release.

Differences in HIV burden in the inflamed and non-inflamed colon from a person living with HIV and ulcerative colitis

The greatest obstacle to an HIV cure is the persistence of latently infected cellular reservoirs in people living with HIV (PLWH) taking antiretroviral therapy (ART). However, no consensus exists on the direct link between local tissue inflammation and the HIV burden. Herein, we have compared the levels of local inflammation, epithelial integrity and HIV DNA between inflamed and non-inflamed colon tissue in a PLWH who underwent a colectomy due to ulcerative colitis. We have observed a 27-fold higher frequency of cells harboring HIV DNA in inflamed compared to non-inflamed colon tissue. Analysis of the expression of occludin-1 and claudin-3 confirmed our macroscopic characterization of inflamed and non-inflamed colon. Our results confirm that increased gut permeability and inflammation are associated with a higher frequency of infected cells and suggest that restoring gut barrier integrity may be used as a strategy to reduce inflammation and HIV persistence in the gut.

Stem cell-derived CAR T cells traffic to HIV reservoirs in macaques

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) with CCR5^– donor cells is the only treatment known to cure HIV-1 in patients with underlying malignancy. This is likely due to a donor cell–mediated graft-versus-host effect targeting HIV reservoirs. Allo-HSCT would not be an acceptable therapy for most people living with HIV due to the transplant-related side effects. Chimeric antigen receptor (CAR) immunotherapies specifically traffic to malignant lymphoid tissues (lymphomas) and, in some settings, are able to replace allo-HSCT. Here, we quantified the engraftment of HSC-derived, virus-directed CAR T cells within HIV reservoirs in a macaque model of HIV infection, using potentially novel IHC assays. HSC-derived CAR cells trafficked to and displayed multilineage engraftment within tissue-associated viral reservoirs, persisting for nearly 2 years in lymphoid germinal centers, the brain, and the gastrointestinal tract. Our findings demonstrate that HSC-derived CAR⁺ cells reside long-term and proliferate in numerous tissues relevant for HIV infection and cancer.

Shared Mechanisms Govern HIV Transcriptional Suppression in Circulating CD103+ and Gut CD4+ T Cells

Latent HIV infection is the main barrier to cure, and most HIV-infected cells reside in the gut, where distinct but unknown mechanisms may promote viral latency. Transforming growth factor β (TGF-β), which induces the expression of CD103 on tissue-resident memory T cells, has been implicated in HIV latency. Using CD103 as a surrogate marker to identify cells that have undergone TGF-β signaling, we compared the HIV RNA/DNA contents and cellular transcriptomes of CD103+ and CD103- CD4 T cells from the blood and rectum of HIV-negative (HIV-) and antiretroviral therapy (ART)-suppressed HIV-positive (HIV+) individuals. Like gut CD4+ T cells, circulating CD103+ cells harbored more HIV DNA than did CD103- cells but transcribed less HIV RNA per provirus. Circulating CD103+ cells also shared a gene expression profile that is closer to that of gut CD4 T cells than to that of circulating CD103- cells, with significantly lower expression levels of ribosomal proteins and transcriptional and translational pathways associated with HIV expression but higher expression levels of a subset of genes implicated in suppressing HIV transcription. These findings suggest that blood CD103+ CD4 T cells can serve as a model to study the molecular mechanisms of HIV latency in the gut and reveal new cellular factors that may contribute to HIV latency.IMPORTANCE The ability of HIV to establish a reversibly silent, "latent" infection is widely regarded as the main barrier to curing HIV. Most HIV-infected cells reside in tissues such as the gut, but it is unclear what mechanisms maintain HIV latency in the blood or gut. We found that circulating CD103+ CD4+ T cells are enriched for HIV-infected cells in a latent-like state. Using RNA sequencing (RNA-seq), we found that CD103+ T cells share a cellular transcriptome that more closely resembles that of CD4+ T cells from the gut, suggesting that they are homing to or from the gut. We also identified the cellular genes whose expression distinguishes gut CD4+ or circulating CD103+ T cells from circulating CD103- T cells, including some genes that have been implicated in HIV expression. These genes may contribute to latent HIV infection in the gut and may serve as new targets for therapies aimed at curing HIV.

Toll-like receptor distribution in colonic epithelium and lamina propria is disrupted in HIV viremic, immune success, and failure

DESIGN

Since intestinal immunity and the microbiome are disrupted in HIV disease, we studied the abundance of innate immune sensors, Toll-like receptors (TLRs), in the mucosa of participants with viremia, prior to antiretroviral therapy (ART), immune success (>500 CD4 T cells/μl after 2 years of ART; suppressed viremia), and immune failure (<350 CD4 T cells/μl after 2 years of ART; suppressed viremia). We hypothesized that disruption of intestinal TLR abundance and location provides a mechanism behind persistent inflammation.

METHODS

Immunofluorescence for TLR3, TLR4, and TLR9 on paraffin embedded biopsies from uninfected, viremic, immune success, and immune failure colons was imaged by deconvolution microscopy and quantified with MetaMorph software. Plasma levels of C-reactive protein, IL-6, and intestinal fatty-acid binding protein (I-FABP) were correlated with TLR expression.

RESULTS

Viremic participants have significantly higher levels of TLR3 and TLR9 on surface epithelium and in crypts when compared with uninfected controls. TLR3 is further elevated in immune failure and immune success. TLR9 abundance remains elevated in immune failure and is normalized in immune success. TLR9 expression in the crypt and lamina propria positively associates with C-reactive protein and IL-6 and negatively with I-FABP. TLR4 is significantly lower on surface epithelium and higher in crypts in viremic. Its expression in the lamina propria positively correlates with IL-6 and negatively correlates with I-FABP.

CONCLUSION

Mucosal TLR imbalance and deregulation, and the resulting mucosal TLR desensitization and hypervigilance, remain after suppressive ART, in the presence or absence of T-cell recovery, likely contributing to chronic systemic inflammation.

The Role of Macrophages in HIV-1 Persistence and Pathogenesis

Current antiretroviral therapy (ART) effectively suppresses Human Immunodeficiency Virus type 1 (HIV-1) in infected individuals. However, even long term ART does not eradicate HIV-1 infected cells and the virus persists in cellular reservoirs. Beside memory CD4⁺ T cells, cells of the myeloid lineage, especially macrophages, are believed to be an important sanctuary for HIV-1. Monocytes and macrophages are key players in the innate immune response to pathogens and are recruited to sites of infection and inflammation. Due to their long life span and ability to reside in virtually every tissue, macrophages have been proposed to play a critical role in the establishment and persistence of the HIV-1 reservoir. Current HIV-1 cure strategies mainly focus on the concept of “shock and kill” to purge the viral reservoir. This approach aims to reactivate viral protein production in latently infected cells, which subsequently are eliminated as a consequence of viral replication, or recognized and killed by the immune system. Macrophage susceptibility to HIV-1 infection is dependent on the local microenvironment, suggesting that molecular pathways directing differentiation and polarization are involved. Current latency reversing agents (LRA) are mainly designed to reactivate the HIV-1 provirus in CD4+ T cells, while their ability to abolish viral latency in macrophages is largely unknown. Moreover, the resistance of macrophages to HIV-1 mediated kill and the presence of infected macrophages in immune privileged regions including the central nervous system (CNS), may pose a barrier to elimination of infected cells by current “shock and kill” strategies. This review focusses on the role of monocytes/macrophages in HIV-1 persistence. We will discuss mechanisms of viral latency and persistence in monocytes/macrophages. Furthermore, the role of these cells in HIV-1 tissue distribution and pathogenesis will be discussed.

Between a shock and a hard place: challenges and developments in HIV latency reversal

Latently infected cells that persist in HIV-infected individuals on antiretroviral therapy (ART) are a major barrier to cure. One strategy to eliminate latency is by activating viral transcription, commonly called latency reversal. Several small non-randomised clinical trials of latency reversing agents (LRAs) in HIV-infected individuals on ART increased viral production, but disappointingly did not reduce the number of latently infected cells or delay time to viral rebound following cessation of ART. More recent approaches aimed at reversing latency include compounds that both activate virus and also modulate immunity to enhance clearance of infected cells. These immunomodulatory LRAs include toll-like receptor agonists, immune checkpoint inhibitors and some cytokines. Here, we provide a brief review of the rationale for transcription-activating and immunomodulatory LRAs, discuss recent clinical trials and some suggestions for combination approaches and research priorities for the future.

Reconstitution of HIV-1 reservoir following high-dose chemotherapy/autologous stem cell transplantation for lymphoma

OBJECTIVES

Autologous stem cell transplantation following high-dose chemotherapy (HDC/ASCT) is the prime model to study the impact of HDC in HIV-1-infected participants. We analyzed the impact of HDC/ASCT on the resurgent reservoir composition and origin.

DESIGN

We included retrospectively a homogenous group of HIV-1-infected patients treated for high-risk lymphoma in a reference center with similar chemotherapy regimens.

METHODS

Thirteen participants treated with HDC/ASCT from 2012 to 2015 were included. A median seven longitudinal blood samples per participant were available. Total HIV-1 DNA levels in peripheral blood mononuclear cells (PBMCs) were quantified by quantitative PCR. In six participants with sustained viral suppression, the highly variable C2V3 viral region was subjected to next-generation sequencing. Maximum-likelihood phylogeny trees were generated from the reconstructed viral haplotypes. Lymphocyte subsets were studied by flow cytometry.

RESULTS

PBMC-associated HIV-1 DNA levels were stable over time. Viral diversity decreased along lymphoma treatment, but increased promptly back to prechemotherapy numbers after HDC/ASCT. Blood viral populations from all time-points were intermingled in phylogeny trees: the resurgent reservoir was similar to pre-HDC circulating proviruses. Memory subsets were the main contributor to the early restoration of the CD4+ T-cell pool, with a delayed increase in naïve cell counts.

CONCLUSIONS

The characterization of HIV-1 reservoir in blood revealed a fast and consistent replenishment from memory CD4+ T cells after HDC/ASCT. As HDC/ASCT is increasingly involved in HIV cure trials with gene-modified hematopoietic stem cells, the management of infected T cells in HIV-positive autologous transplants will be critical.

The Role of Macrophages in HIV-1 Persistence and Pathogenesis

Current antiretroviral therapy (ART) effectively suppresses Human Immunodeficiency Virus type 1 (HIV-1) in infected individuals. However, even long term ART does not eradicate HIV-1 infected cells and the virus persists in cellular reservoirs. Beside memory CD4⁺ T cells, cells of the myeloid lineage, especially macrophages, are believed to be an important sanctuary for HIV-1. Monocytes and macrophages are key players in the innate immune response to pathogens and are recruited to sites of infection and inflammation. Due to their long life span and ability to reside in virtually every tissue, macrophages have been proposed to play a critical role in the establishment and persistence of the HIV-1 reservoir. Current HIV-1 cure strategies mainly focus on the concept of "shock and kill" to purge the viral reservoir. This approach aims to reactivate viral protein production in latently infected cells, which subsequently are eliminated as a consequence of viral replication, or recognized and killed by the immune system. Macrophage susceptibility to HIV-1 infection is dependent on the local microenvironment, suggesting that molecular pathways directing differentiation and polarization are involved. Current latency reversing agents (LRA) are mainly designed to reactivate the HIV-1 provirus in CD4+ T cells, while their ability to abolish viral latency in macrophages is largely unknown. Moreover, the resistance of macrophages to HIV-1 mediated kill and the presence of infected macrophages in immune privileged regions including the central nervous system (CNS), may pose a barrier to elimination of infected cells by current "shock and kill" strategies. This review focusses on the role of monocytes/macrophages in HIV-1 persistence. We will discuss mechanisms of viral latency and persistence in monocytes/macrophages. Furthermore, the role of these cells in HIV-1 tissue distribution and pathogenesis will be discussed.

Nonhuman Primate Models and Understanding the Pathogenesis of HIV Infection and AIDS

Research using nonhuman primates (NHPs) as models for human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) has resulted in tremendous achievements not only in the prevention and treatment of HIV, but also in biomedical research more broadly. Once considered a death sentence, HIV infection is now fairly well controlled with combination antiretroviral treatments, almost all of which were first tested for efficacy and safety in nonhuman primates or other laboratory animals. Research in NHP has led to "dogma changing" discoveries in immunology, infectious disease, and even our own genetics. We now know that many of our genes are retroviral remnants, or developed in response to archaic HIV-like retroviral infections. Early studies involving blood from HIV patients and in experiments in cultured tissues contributed to confusion regarding the cause of AIDS and impeded progress in the development of effective interventions. Research on the many retroviruses of different NHP species have broadened our understanding of human immunology and perhaps even our origins and evolution as a species. In combination with recent advances in molecular biology and computational analytics, research in NHPs has unique potential for discoveries that will directly lead to new cures for old human and animal diseases, including HIV/AIDS.

Sexual dimorphism in HIV-1 infection

Sex-specific differences affecting various aspects of HIV-1 infection have been reported, including differences in susceptibility to infection, course of HIV-1 disease, and establishment of viral reservoirs. Once infected, initial plasma levels of HIV-1 viremia in women are lower compared to men while the rates of progression to AIDS are similar. Factors contributing to these sex differences are poorly understood, and range from anatomical differences and differential expression of sex hormones to differences in immune responses, the microbiome and socio-economic discrepancies, all of which may impact HIV-1 acquisition and disease progression. Ongoing research efforts aiming at controlling HIV-1 disease or reducing viral reservoirs need to take these sex-based differences in HIV-1 pathogenesis into account. In this review, we discuss established knowledge and recent findings on immune pathways leading to sex differences in HIV-1 disease manifestations, with focus on HIV-1 latency and the effect of female sex hormones on HIV-1.

Butyrylcholinesterase Levels on Admission Predict Severity and 12-Month Mortality in Hospitalized AIDS Patients

Background

Butyrylcholinesterase (BChE) is synthesized mainly in the liver and an important marker in many infectious/inflammatory diseases, but its role in acquired immunodeficiency syndrome (AIDS) patients is not clear. We wished to ascertain if BChE level is associated with the progression/prognosis of AIDS patients.

Methods

BChE levels (in U/L) were measured in 505 patients; <4500 was defined as “low” and ≥4500 as “normal.” Associations between BChE level and CD4 count, WHO stage, body mass index (BMI), C-reactive protein (CRP) level, and duration of hospitalization were assessed. Kaplan–Meier curves and Cox proportional hazards model were used to assess associations between low BChE levels and mortality, after adjustment for age, CD4 count, WHO stage, and laboratory parameters.

Results

A total of 129 patients (25.5%) had a lower BChE level. BChE was closely associated with CD4 count, WHO stage, CRP level, and BMI (all P < 0.001). Eighty-four patients (16.6%) died in the first year of follow-up. One-year survival was 64.5 ± 4.5% for patients with low BChE and 87.6 ± 1.8% for those with normal BChE (log-rank, P < 0.001). After adjustment for sex, age, BMI, WHO stage, and CD4 count, as well as serum levels of hemoglobin, sodium, and albumin, the hazard ratio was 1.8 (95% confidence interval, 1.0–3.2) for patients with a low BChE compared with those with a normal BChE (P = 0.035).

Conclusion

BChE level is associated with HIV/AIDS severity and is an independent risk factor for increased mortality in AIDS patients.

The Female Genital Tract Microbiome Is Associated With Vaginal Antiretroviral Drug Concentrations in Human Immunodeficiency Virus-Infected Women on Antiretroviral Therapy

Background

The female genital tract (FGT) microbiome may affect vaginal pH and other factors that influence drug movement into the vagina. We examined the relationship between the microbiome and antiretroviral concentrations in the FGT.

Methods

Over one menstrual cycle, 20 human immunodeficiency virus (HIV)-infected women virologically suppressed on tenofovir (TFV) disoproxil fumarate/emtricitabine and ritonavir-boosted atazanavir (ATV) underwent serial paired cervicovaginal and plasma sampling for antiretroviral concentrations using high-performance liquid chromatography-tandem mass spectrometry. Analysis of 16S ribosomal RNA gene sequencing of cervicovaginal lavage clustered each participant visit into a unique microbiome community type (mCT).

Results

Participants were predominantly African American (95%), with a median age of 38 years. Cervicovaginal lavage sequencing (n = 109) resulted in a low-diversity mCT dominated by Lactobacillus (n = 40), and intermediate-diversity (n = 28) and high-diversity (n = 41) mCTs with abundance of anaerobic taxa. In multivariable models, geometric mean FGT:plasma ratios varied significantly by mCT for all 3 drugs. For both ATV and TFV, FGT:plasma was significantly lower in participant visits with high- and low-diversity mCT groups (all P < .02). For emtricitabine, FGT:plasma was significantly lower in participant visits with low- vs intermediate-diversity mCT groups (P = .002).

Conclusions

Certain FGT mCTs are associated with decreased FGT antiretroviral concentrations. These findings are relevant for optimizing antiretrovirals used for biomedical HIV prevention in women.

Differentiating Immune Cell Targets in Gut-Associated Lymphoid Tissue for HIV Cure

The single greatest challenge to an HIV cure is the persistence of latently infected cells containing inducible, replication-competent proviral genomes, which constitute only a small fraction of total or infected cells in the body. Although resting CD4⁺ T cells in the blood are a well-known source of viral rebound, more than 90% of the body's lymphocytes reside elsewhere. Many are in gut tissue, where HIV DNA levels per million CD4⁺ T cells are considerably higher than in the blood. Despite the significant contribution of gut tissue to viral replication and persistence, little is known about the cell types that support persistence of HIV in the gut; importantly, T cells in the gut have phenotypic, functional, and survival properties that are distinct from T cells in other tissues. The mechanisms by which latency is established and maintained will likely depend on the location and cytokine milieu surrounding the latently infected cells in each compartment. Therefore, successful HIV cure strategies require identification and characterization of the exact cell types that support viral persistence, particularly in the gut. In this review, we describe the seeding of the latent HIV reservoir in the gut mucosa; highlight the evidence for compartmentalization and depletion of T cells; summarize the immunologic consequences of HIV infection within the gut milieu; propose how the damaged gut environment may promote the latent HIV reservoir; and explore several immune cell targets in the gut and their place on the path toward HIV cure.

Unique microRNA expression in the colonic mucosa during chronic HIV-1 infection

OBJECTIVE

Chronic HIV-1 infection leads to widespread inflammation and immune dysregulation. The gastrointestinal mucosa, a primary site for HIV-1 replication, is thought to play a significant role in this response. MicroRNAs (miRs) are small noncoding RNAs that regulate gene expression, including immune activation and inflammation. Here we investigate miR expression and function in the colonic mucosa during HIV-1 infection.

DESIGN AND METHODS

Using miR profiling, we examined miR expression in the colonic mucosa of HIV-infected patients. These miRs were further parsed to identify those that most likely function in HIV-related inflammation. Using bioinformatics tools, we identified potential target genes which were confirmed using in-vitro functional testing.

RESULTS

We identified 12 miRs that were differentially expressed in the colonic mucosa of HIV-infected patients with high versus undetectable plasma viral concentrations. Of these, both miR-26a and miR-29a were downregulated in untreated HIV-1 infection, yet not in the colonic mucosa from inflammatory bowel disease. This downregulation occurs within the first hours after infection. These miRs were further shown to directly target IL-6 and STAT3, respectively, with similar changes confirmed in an ex-vivo explant infection model.

CONCLUSION

miR-26a and miR-29a levels are decreased in the colonic mucosa during chronic HIV-1 infection, and this change may be initiated during acute infection. Both miRs de-repress the IL-6/STAT3 signaling pathway, which could contribute to increased inflammation during infection. These miRs may represent novel therapeutic targets for HIV-1-associated inflammation in the colonic mucosa.

Tissue reservoirs of HIV

PURPOSE OF REVIEW

Tissue reservoirs of HIV may promote the persistent immunopathology responsible for non-AIDS morbidity and data support multifocal reactivation from tissues as the source of viral rebound during antiretroviral therapy (ART) interruption. The heterogeneity of tissue reservoirs and incomplete knowledge about their composition are obstacles to an HIV cure.

RECENT FINDINGS

In addition to the higher concentration of infected CD4 T cells found in both central lymphoid tissues and gut, specific subsets of CD4 T cells appear to play a disproportionate role in HIV persistence. Recently, a subset of central memory T cells enriched in lymph node germinal centers called T-follicular helper cells has been identified that expresses more viral RNA and occupies an anatomic niche inaccessible to cytotoxic T lymphocyte killing. Additional observations suggest that antiretroviral drug (ARV) concentrations may be lower in some tissues, raising the possibility for localized, low-level viral replication. Finally, some recent data implicate the persistence of infected, non-CD4 T-cell types in tissues during ART.

SUMMARY

The retention of infected cells in a wide variety of tissues, often with distinct viral and cellular characteristics, underscores the importance of studying tissue reservoirs in the development and assessment of cure strategies. Both inhibitory ARVs and latency-reversing drugs must reach these sites, and novel strategies may be needed to attack virus in cells as variable as T-follicular helper cells and macrophages.

Shocking HIV out of hiding: where are we with clinical trials of latency reversing agents?

PURPOSE OF REVIEW

To provide an overview of the initial experiences with the use of latency-reversing agents (LRAs) in clinical trials in HIV and to discuss and contrast results arising from these studies.

RECENT FINDINGS

Although the clinical administration of histone deacetylase inhibitors (HDACis) and disulfiram to HIV-infected individuals on antiretroviral therapy significantly increased cell-associated HIV RNA in CD4 T cells and in some cases plasma HIV RNA, this did not reduce the frequency of latently infected cells in blood. Potential reasons for this include insufficient potency in latency reversal, lack of virus or immune-mediated cytolysis of virus-expressing cells and/or a high frequency of immune escape mutations in the recently activated virus. Analyses of HIV-specific T-cell responses in vivo did not demonstrate that HDACis impair immune cell effector functions.

SUMMARY

More effective latency-reversing interventions and additional strategies to eliminate virus-expressing cells are needed. Key challenges include testing combinations of LRAs and/or LRAs with immune modulation to optimize potency in the absence of adverse events. A better understanding of the mechanisms of action of LRAs as well as strategies to enhance potency and penetration in tissue are key challenges for future studies.

Sensitive quantification of the HIV-1 reservoir in gut-associated lymphoid tissue

Background

The implementation of successful strategies to achieve an HIV cure has become a priority in HIV research. However, the current location and size of HIV reservoirs is still unknown since there are limited tools to evaluate HIV latency in viral sanctuaries such as gut-associated lymphoid tissue (GALT). As reported in the so called “Boston Patients”, despite undetectable levels of proviral HIV-1 DNA in blood and GALT, viral rebound happens in just few months after ART interruption. This fact might imply that current methods are not sensitive enough to detect residual reservoirs. Showing that, it is imperative to improve the detection and quantification of HIV-1 reservoir in tissue samples. Herein, we propose a novel non-enzymatic protocol for purification of Lamina Propria Leukocytes (LPL) from gut biopsies combined to viral HIV DNA (vDNA) quantification by droplet digital PCR (ddPCR) to improve the sensitivity and accuracy of viral reservoir measurements (LPL-vDNA assay).

Methods

Endoscopic ileum biopsies were sampled from 12 HIV-1-infected cART-suppressed subjects. We performed a DTT/EDTA-based treatment for epithelial layer removal followed by non-enzymatic disruption of the tissue to obtain lamina propria cell suspension (LP). CD45⁺ cells were subsequently purified by flow sorting and vDNA was determined by ddPCR.

Results

vDNA quantification levels were significantly higher in purified LPLs (CD45⁺) than in bulk LPs (p<0.01). The levels of vDNA were higher in ileum samples than in concurrent PBMC from the same individuals (p = 0.002). As a result of the increased sensitivity of this purification method, the Poisson 95% confidence intervals of the vDNA quantification data from LPLs were narrower than that from bulk LPs. Of note, vDNA was unambiguously quantified above the detection limit in 100% of LPL samples, while only in 58% of bulk LPs.

Conclusion

We propose an innovative combined protocol for a more sensitive detection of the HIV reservoir in gut-associated viral sanctuaries, which might be used to evaluate any proposed eradication strategy.

Initiation of antiretroviral therapy before detection of colonic infiltration by HIV reduces viral reservoirs, inflammation and immune activation

Introduction

Colonic infiltration by HIV occurs soon after infection, establishing a persistent viral reservoir and a barrier to cure. We investigated virologic and immunologic correlates of detectable colonic HIV RNA during acute HIV infection (AHI) and their response to antiretroviral treatment (ART).

Methods

From 49,458 samples screened for HIV, 74 participants were enrolled during AHI and 41 consented to optional sigmoidoscopy, HIV RNA was categorized as detectable (≥50 copies/mg) or undetectable in homogenized colon biopsy specimens. Biomarkers and HIV burden in blood, colon and cerebrospinal fluid were compared between groups and after 24 weeks of ART.

Results

Colonic HIV RNA was detectable in 31 participants (76%) and was associated with longer duration since HIV exposure (median 16 vs. 11 days, p=0.02), higher median plasma levels of cytokines and inflammatory markers (CXCL10 476 vs. 148 pg/mL, p=0.02; TNF-RII 1036 vs. 649 pg/mL, p<0.01; neopterin 2405 vs. 1368 pg/mL, p=0.01) and higher levels of CD8+ T cell activation in the blood (human leukocyte antigen - antigen D related (HLA-DR)/CD38 expression 14.4% vs. 7.6%, p <0.01) and colon (8.9% vs. 4.5%, p=0.01). After 24 weeks of ART, participants with baseline detectable colonic HIV RNA demonstrated persistent elevations in total HIV DNA in colonic mucosal mononuclear cells (CMMCs) (median 61 vs. 0 copies/10⁶ CMMCs, p=0.03) and a trend towards higher total HIV DNA in peripheral blood mononuclear cells (PBMC) (41 vs. 1.5 copies/10⁶ PBMCs, p=0.06). There were no persistent differences in immune activation and inflammation.

Conclusions

The presence of detectable colonic HIV RNA at the time of ART initiation during AHI is associated with higher levels of proviral DNA after 24 weeks of treatment. Seeding of HIV in the gut may have long-lasting effects on the size of persistent viral reservoirs and may represent an important therapeutic target in eradication strategies.

Markov process models of the dynamics of HIV reservoirs

While latently infected CD4+ T cells are extremely sparse, they are a reality that prevents HIV from being cured, and their dynamics are largely unknown. We begin with a two-state Markov process that models the outcomes of regular but infrequent blood tests for latently infected cells in an HIV positive patient under drug therapy. We then model the hidden dynamics of a latently infected CD4+ T cell in an HIV positive patient and show there is a limiting distribution, which indicates in which compartments the HIV typically can be found. Our model shows that the limiting distribution of latently infected cells reveals the presence of latency in every compartment with positive probability, supported by clinical data. We also show that the hidden Markov model determines the outcome of blood tests and analyze its connection to the blood test model.

Barriers to a cure for HIV in women

Introduction

Distinct biological factors exist that affect the natural history of HIV and the host immune response between women and men. These differences must be addressed to permit the optimal design of effective HIV eradication strategies for much of the HIV-positive population.

Methods and results

Here, we review the literature on sex-based differences in HIV pathogenesis and natural history in tissues and anatomic compartments, HIV latency and transcriptional activity, and host immunity including the role of sex hormones. We then outline the potential effects of these differences on HIV persistence, and on the safety and efficacy of HIV eradication and curative interventions. Finally, we discuss the next steps necessary to elucidate these factors to achieve a cure for HIV, taking in account the complex ethical issues and the regulatory landscape in the hopes of stimulating further research and awareness in these areas.

Conclusions

Targeted enrolment of women in clinical trials and careful sex-based analysis will be crucial to gain further insights into sex-based differences in HIV persistence and to design sex-specific approaches to HIV eradication, if required.

[Key role played by the gut associated lymphoid tissue during human immunodeficiency virus infection]

The gut associated lymphoid tissue (GALT) is the site of numerous immunological disturbances during HIV-1 infection. It constitutes the largest reservoir for HIV, not or very poorly susceptible to antiretroviral therapy (ART), making it a major obstacle to HIV cure. Moreover, the GALT is involved in systemic immune activation in HIV-infected individuals: intestinal damage due to viral replication and severe CD4(+) T cell depletion in the GALT leads to microbial translocation, a key driver of immune activation, and in turn, disease progression. In this review, we describe the role of the GALT in HIV infection and we discuss therapeutic options to decrease the intestinal viral reservoir and to preserve immune function in the gut of HIV-infected people. Achieving these goals is necessary for a long-term infection control after the interruption of ART.

Epigenetic control of HIV-1 post integration latency: implications for therapy

With the development of effective combined anti-retroviral therapy (cART), there is significant reduction in deaths associated with human immunodeficiency virus type 1 (HIV-1) infection. However, the complete cure of HIV-1 infection is difficult to achieve without the elimination of latent reservoirs which exist in the infected individuals even under cART regimen. These latent reservoirs established during early infection have long life span, include resting CD4⁺ T cells, macrophages, central nervous system (CNS) resident macrophage/microglia, and gut-associated lymphoid tissue/macrophages, and can actively produce virus upon interruption of the cART. Several epigenetic and non-epigenetic mechanisms have been implicated in the regulation of viral latency. Epigenetic mechanisms such as histone post translational modifications (e.g., acetylation and methylation) and DNA methylation of the proviral DNA and microRNAs are involved in the establishment of HIV-1 latency. The better understanding of epigenetic mechanisms modulating HIV-1 latency could give clues for the complete eradication of these latent reservoirs. Several latency-reversing agents (LRA) have been found effective in reactivating HIV-1 reservoirs in vitro, ex vivo, and in vivo. Some of these agents target epigenetic modifications to elicit viral expression in order to kill latently infected cells through viral cytopathic effect or host immune response. These therapeutic approaches aimed at achieving a sterilizing cure (elimination of HIV-1 from the human body). In the present review, we will discuss our current understanding of HIV-1 epigenomics and how this information can be moved from the laboratory bench to the patient’s bedside.

Changes in HIV reservoirs during long-term antiretroviral therapy

PURPOSE OF REVIEW

To review current knowledge about the impact of long-term combination antiretroviral therapy (cART) on HIV reservoirs.

RECENT FINDINGS

The number of HIV-infected cells that persist during long-term antiretroviral therapy is associated with the stage of HIV infection at the time of treatment initiation. Initiation of cART reduces the number of infected cells over the first 4 years of therapy, but thereafter there is no further decline despite long-term effective cART. The remarkable stability of infected cell numbers is likely due to a balance among homeostatic or antigen-driven proliferation of infected memory T-cells subsets, clonal expansion of a subset of infected cells as a consequence of specific retroviral integration sites, and death of other infected cells. At present, there is no effective means of accelerating the decay of infected cells in individuals initiated on cART during chronic HIV infection.

SUMMARY

Given the stability and difficulty in eliminating HIV-infected cells, early initiation of cART in treatment-naïve HIV-infected patients is currently the most effective way to limit the size and diversity of HIV reservoirs.

Significant Depletion of CD4(+) T Cells Occurs in the Oral Mucosa during Simian Immunodeficiency Virus Infection with the Infected CD4(+) T Cell Reservoir Continuing to Persist in the Oral Mucosa during Antiretroviral Therapy

Human and simian immunodeficiency virus (HIV and SIV) infections are characterized by manifestation of numerous opportunistic infections and inflammatory conditions in the oral mucosa. The loss of CD4⁺ T cells that play a critical role in maintaining mucosal immunity likely contributes to this process. Here we show that CD4⁺ T cells constitute a minor population of T cells in the oral mucosa and display a predominantly central memory phenotype mirroring other mucosal sites such as the rectal mucosa. Chronic SIV infection was associated with a near total depletion of CD4⁺ T cells in the oral mucosa that appear to repopulate during antiretroviral therapy (ART). Repopulating CD4⁺ T cells harbored a large fraction of Th17 cells suggesting that ART potentially reconstitutes oral mucosal immunity. However, a minor fraction of repopulating CD4⁺ T cells harbored SIV DNA suggesting that the viral reservoir continues to persist in the oral mucosa during ART. Therapeutic approaches aimed at obtaining sustainable CD4⁺ T cell repopulation in combination with strategies that can eradicate the latent viral reservoir in the oral mucosa are essential for better oral health and long-term outcome in HIV infected patients.

Persistent production of an integrase-deleted HIV-1 variant with no resistance mutation and wild-type proviral DNA in a treated patient

An HIV-infected patient presenting an unexpected viral escape under combined antiretroviral treatment is described. The virus isolated from plasma contained a large deletion in the HIV-1 integrase gene but no known resistance mutation. Nested polymerase chain reactions (PCRs) with patient virus integrase-specific primers and probes were developed and used to detect the mutant from plasma, blood, rectal biopsies, and sperm. The variant progressively emerged during a period of therapy-induced virosuppression, and persisted at a low but detectable level for at least 5 years. Surprisingly, proviral DNA from lymphocytes, rectal cells, and sperm cells was, and remained, mainly wild type. Cellular HIV RNA with the deletion was detected only once from the rectum. The origin and mechanisms underlying this so far not described production at a detectable level are largely hypothetical. This observation raised concern about the ability of defective viruses to spread.

Synthetic consensus HIV-1 DNA induces potent cellular immune responses and synthesis of granzyme B, perforin in HIV infected individuals

This study evaluated the safety and immunogenicity of PENNVAX-B in 12 HIV infected individuals. PENNVAX-B is a combination of three optimized synthetic plasmids encoding for multiclade HIV Gag and Pol and a consensus CladeB Env delivered by electroporation. HIV infected individuals whose virus was effectively suppressed using highly active antiretroviral therapy (HAART) received PENNVAX-B DNA followed by electroporation with CELLECTRA-5P at study weeks 0, 4, 8, and 16. Local administration site and systemic reactions to PENNVAX-B were recorded after each treatment along with any adverse events. Pain of the treatment procedure was assessed using a Visual Analog Scale. Whole PBMCs were isolated for use in IFN ELISpot and Flow Cytometric assays. PENNVAX-B was generally safe and well tolerated. Overall, the four dose regimen was not associated with any serious adverse events or severe local or systemic reactions. A rise in antigen-specific SFU was detected in the INFγ ELISpot assay in all 12 participants. T cells from 8/12 participants loaded with both granzyme B and perforin in response to HIV antigen, an immune finding characteristic of long-term nonprogressors (LTNPs) and elite controllers (ECs). Thus administration of PENNVAX-B may prove useful adjunctive therapy to ART for treatment and control of HIV infection.

Design aspects of a case-control clinical investigation of the effect of HIV on oral and gastrointestinal soluble innate factors and microbes

INTRODUCTION

The impaired host defense system in HIV infection impacts the oral and gastrointestinal microbiota and associated opportunistic infections. Antiretroviral treatment is predicted to partially restore host defenses and decrease the oral manifestation of HIV/AIDS. Well-designed longitudinal studies are needed to better understand the interactions of soluble host defense proteins with bacteria and virus in HIV/AIDS. "Crosstalk" was designed as a longitudinal study of host responses along the gastrointestinal (GI) tract and interactions between defense molecules and bacteria in HIV infection and subsequent therapy.

PURPOSE

The clinical core formed the infrastructure for the study of the interactions between the proteome, microbiome and innate immune system. The core recruited and retained study subjects, scheduled visits, obtained demographic and medical data, assessed oral health status, collected samples, and guided analysis of the hypotheses. This manuscript presents a well-designed clinical core that may serve as a model for studies that combine clinical and laboratory data.

METHODS

Crosstalk was a case-control longitudinal clinical study an initial planned enrollment of 170 subjects. HIV+ antiretroviral naïve subjects were followed for 9 visits over 96 weeks and HIV uninfected subjects for 3 visits over 24 weeks. Clinical prevalence of oral mucosal lesions, dental caries and periodontal disease were assessed.

RESULTS

During the study, 116 subjects (47 HIV+, 69 HIV-) were enrolled. Cohorts of HIV+ and HIV- were demographically similar except for a larger proportion of women in the HIV- group. The most prevalent oral mucosal lesions were oral candidiasis and hairy leukoplakia in the HIV+ group.

DISCUSSION

The clinical core was essential to enable the links between clinical and laboratory data. The study aims to determine specific differences between oral and GI tissues that account for unique patterns of opportunistic infections and to delineate the differences in their susceptibility to infection by HIV and their responses post-HAART.

Phosphodiesterase 8a supports HIV-1 replication in macrophages at the level of reverse transcription

BACKGROUND

HIV-1 infected macrophages play a key role in HIV-1 infection. Even during anti-retroviral treatment, macrophages keep producing virus due to suboptimal tissue penetration and reduced efficacy of antiretrovirals. It is therefore of major importance to understand which host factors are involved in HIV-1 replication in macrophages. Previously, we have shown that genetic polymorphisms in phosphodiesterase 8a (PDE8A) are strongly associated with HIV-1 replication in these cells. Here we analyzed the mechanism and regulation of PDE8A in HIV-1 replication in macrophages.

RESULTS

PDE8A mRNA expression strongly increases upon differentiation of monocytes into macrophages, which corresponds to the increased susceptibility of mature macrophages to HIV-1. In parallel, expression of microRNA miR-145-5p, predicted to target PDE8A mRNA, strongly decreased. The interaction of miR-145-5p with the 3' UTR of PDE8A mRNA could be experimentally validated, suggesting that indeed miR-145-5p can regulate PDE8A expression levels. Knockdown of PDE8A in macrophages resulted in a decrease in total HIV-1 replication and proviral DNA levels. These observations confirm that PDE8A regulates HIV-1 replication in macrophages and that this effect is mediated through early steps in the viral replication cycle.

CONCLUSIONS

PDE8A is highly expressed in macrophages, and its expression is regulated by miR-145-5p. Our findings strongly suggest that PDE8A supports HIV-1 replication in macrophages and that this effect is mediated at the level of reverse transcription.

Immunomodulation of antiretroviral drug-suppressed chronic HIV-1 infection in an oral probiotic double-blind placebo-controlled trial

A putative source of inappropriate immune activation that drives human immunodeficiency virus (HIV)-1 immunopathogenesis is the gastrointestinal tract. Even with effective antiretroviral treatment, residual activation persists. We hypothesized that an oral probiotic could improve the residual immune activation in chronic treated HIV-1 infection, and tested a Bacillus coagulans GBI-30, 6086 capsule probiotic in HIV-1-infected persons with suppressed viremia on stable antiretroviral therapy in a 3-month double-blind placebo-controlled trial (10 probiotic, 7 placebo). The Gastrointestinal Symptom Rating Scale (GSRS) was administered monthly. Blood was tested at the start and end of placebo/probiotic administration for viremia, CD4(+) T cell percentage/concentration, soluble (s)CD14, soluble intestinal fatty acid binding protein, sCD163, D-dimer, C-reactive protein (CRP), interleukin-8, and tumor necrosis factor-α. All participants maintained viremia <40 RNA copies/ml. The probiotic was safe and well tolerated, and appeared to improve chronic gastrointestinal symptoms. Its administration was associated with a significant increase in the percentage of blood CD4(+) T cells compared to placebo (+2.8% versus -1.8%, p=0.018) although CD4(+) T cell concentrations were generally unchanged in both groups. None of the biomarkers showed significant changes on probiotic treatment or between-group differences in change (although significance was borderline for a greater sCD163 drop in the probiotic versus placebo group, p=0.05). Some biomarkers showed significant correlations to each other, particularly D-dimer with CRP and sCD14 with tumor necrosis factor (TNF)-α. These data demonstrate the safety and possible benefit of this probiotic for residual inflammation in treated HIV-1 infection, although further study will be required to determine the immune pathways involved.

A multisystem investigation of raltegravir association with intestinal tissue: implications for pre-exposure prophylaxis and eradication

OBJECTIVES

Recent clinical data have suggested high raltegravir concentrations in gut tissue after oral administration, with implications for treatment and prevention. We have used in silico, in vitro, ex vivo and in vivo models to further investigate the accumulation of raltegravir in gut tissue.

METHODS

Affinity of raltegravir for gut tissue was assessed in silico (Poulin-Theil method), in vitro (Caco-2 accumulation) and ex vivo (rat intestine) and compared with the lipophilic drug lopinavir. Finally, raltegravir concentrations in plasma, gut contents, small intestine and large intestine were determined after oral dosing to Wistar rats 1 and 4 h post-dose. Samples were analysed using LC-MS/MS and scintillation counting.

RESULTS

Gut tissue accumulation of raltegravir was less than for lopinavir in silico, in vitro and ex vivo (P < 0.05). After oral administration to rats, raltegravir concentrations 4 h post-dose were lower in plasma (0.05 μM) compared with small intestine (0.47 μM, P = 0.06) and large intestine (1.36 μM, P < 0.05). However, raltegravir concentrations in the contents of both small intestine (4.0 μM) and large intestine (40.6 μM) were also high.

CONCLUSIONS

In silico, in vitro and ex vivo data suggest low raltegravir accumulation in intestinal tissue. In contrast, in vivo animal data suggest raltegravir concentrates in intestinal tissue even when plasma concentrations are minimal. However, high raltegravir concentrations in gut contents are the likely driving factor behind this observation, rather than blood-to-tissue drug distribution. The methods described can be combined with clinical investigations to provide a complete strategy for selection of drugs with high gut accumulation.

Effects of treatment with suppressive combination antiretroviral drug therapy and the histone deacetylase inhibitor suberoylanilide hydroxamic acid; (SAHA) on SIV-infected Chinese rhesus macaques

OBJECTIVES

Viral reservoirs-persistent residual virus despite combination antiretroviral therapy (cART)-remain an obstacle to cure of HIV-1 infection. Difficulty studying reservoirs in patients underscores the need for animal models that mimics HIV infected humans on cART. We studied SIV-infected Chinese-origin rhesus macaques (Ch-RM) treated with intensive combination antiretroviral therapy (cART) and 3 weeks of treatment with the histone deacetyalse inhibitor, suberoylanilide hydroxamic acid (SAHA).

METHODS

SIVmac251 infected Ch-RM received reverse transcriptase inhibitors PMPA and FTC and integrase inhibitor L-870812 beginning 7 weeks post infection. Integrase inhibitor L-900564 and boosted protease inhibitor treatment with Darunavir and Ritonavir were added later. cART was continued for 45 weeks, with daily SAHA administered for the last 3 weeks, followed by euthanasia/necropsy. Plasma viral RNA and cell/tissue-associated SIV gag RNA and DNA were quantified by qRT-PCR/qPCR, with flow cytometry monitoring changes in immune cell populations.

RESULTS

Upon cART initiation, plasma viremia declined, remaining <30 SIV RNA copy Eq/ml during cART, with occasional blips. Decreased viral replication was associated with decreased immune activation and partial restoration of intestinal CD4+ T cells. SAHA was well tolerated but did not result in demonstrable treatment-associated changes in plasma or cell associated viral parameters.

CONCLUSIONS

The ability to achieve and sustain virological suppression makes cART-suppressed, SIV-infected Ch-RM a potentially useful model to evaluate interventions targeting residual virus. However, despite intensive cART over one year, persistent viral DNA and RNA remained in tissues of all three animals. While well tolerated, three weeks of SAHA treatment did not demonstrably impact viral RNA levels in plasma or tissues; perhaps reflecting dosing, sampling and assay limitations.

Immune activation is associated with increased gut microbial translocation in treatment-naive, HIV-infected children in a resource-limited setting

BACKGROUND

Gut damage resulting in microbial translocation (MT) is considered a major cause of immune activation (IA) in HIV infection, but data in children are limited, particularly in the absence of antiretroviral therapy.

METHODS

Sixty perinatally HIV-infected, antiretroviral therapy-naive children, aged 2-12 years, were evaluated for plasma levels of lipopolysaccharide, DNA sequences encoding bacterial 16 second ribosomal DNA (16S rDNA) and soluble CD14 concurrently with markers of CD4 and CD8 T-cell IA and immune exhaustion (IE), CD4 counts, and plasma viral load. At study entry, participants were classified into immune categories (ICs): IC1 (CD4% > 25), IC2 (CD4% 15-25), and IC3 (CD4% < 15). Age-matched HIV-uninfected children served as controls. Data were evaluated at study entry and at 12 months.

RESULTS

Levels of MT, IA, and IE were increased in patients as compared with controls, were highest in patients in IC3 group, and did not change over 12 months. MT products lipopolysaccharide and 16S rDNA correlated with each other and each correlated with plasma viral load, soluble CD14, and T-cell IA and IE. There was a correlation of IA with IE. CD4 counts and percentage were inversely correlated with MT products and underlying CD4 activation.

CONCLUSIONS

In a natural history cohort of HIV-infected children not on therapy, MT was more pronounced in the most severely immunocompromised patients and was associated with IA. Strategies to reduce MT may help to reduce IA and prevent CD4 depletion.

The complexity of HIV persistence and pathogenesis in the lung under antiretroviral therapy: challenges beyond AIDS

Antiretroviral therapy (ART) represents a significant milestone in the battle against AIDS. However, we continue learning about HIV and confronting challenges 30 years after its discovery. HIV has cleverly tricked both the host immune system and ART. First, the many HIV subtypes and recombinant forms have different susceptibilities to antiretroviral drugs, which may represent an issue in countries where ART is just being introduced. Second, even under the suppressive pressures of ART, HIV still increases inflammatory mediators, deregulates apoptosis and proliferation, and induces oxidative stress in the host. Third, the preference of HIV for CXCR4 as a co-receptor may also have noxious outcomes, including potential malignancies. Furthermore, HIV still replicates cryptically in anatomical reservoirs, including the lung. HIV impairs bronchoalveolar T-lymphocyte and macrophage immune responses, rendering the lung susceptible to comorbidities. In addition, HIV-infected individuals are significantly more susceptible to long-term HIV-associated complications. This review focuses on chronic obstructive pulmonary disease (COPD), pulmonary arterial hypertension, and lung cancer. Almost two decades after the advent of highly active ART, we now know that HIV-infected individuals on ART live as long as the uninfected population. Fortunately, its availability is rapidly increasing in low- and middle-income countries. Nevertheless, ART is not risk-free: the developed world is facing issues with antiretroviral drug toxicity, resistance, and drug-drug interactions, while developing countries are confronting issues with immune reconstitution inflammatory syndrome. Several aspects of the complexity of HIV persistence and challenges with ART are discussed, as well as suggestions for new avenues of research.

Virological characteristics of occult hepatitis B virus in a North American cohort of human immunodeficiency virus type 1-positive patients on dual active anti-HBV/HIV therapy

BACKGROUND

Occult hepatitis B virus infection (OBI) is defined as low-level HBV DNA presence in serum, liver and/or peripheral blood mononuclear cells (PBMC) in individuals that lack serum hepatitis B virus surface antigen (HBsAg). HIV+ patients with OBI may be at risk for HBV reactivation, and often receive dual active anti-HBV/HIV therapy, such as lamivudine (LMV).

OBJECTIVES

To determine the presence of OBI in a North American cohort of HIV-1-positive patients.

STUDY DESIGN/METHODS

45 HIV-1-positive, serum HBsAg-negative patients, reactive for antibodies to HBV core antigen (anti-HBc), were tested for HBV DNA in plasma and for HBV DNA and covalently closed circular DNA (cccDNA) in PBMC. Ten patients were re-tested after ∼5-10 years, including genotyping and clonal sequence analysis of the HBV polymerase (P) gene and overlapping HBV surface (S) gene from 8 PBMC samples.

RESULTS

Overall, 42% (19/45) tested HBV DNA positive, especially in PBMC (18/45), including 3/18 that were reactive for HBV cccDNA, compared to 17% (8/45) that were HBV DNA reactive in plasma. In 8 patients on LMV, sequence analysis in PBMC showed that all were HBV genotype C or D. Several carried HBV P region variants at residues associated with anti-HBV drug resistance and overlapping S gene region within the major HBsAg "a determinant".

CONCLUSION

OBI is common in HIV-positive, anti-HBc reactive patients on anti-HBV/HIV therapy, particularly in PBMC. HBV sequence analysis revealed that all had HBV genotype C or D and often had P/overlapping S gene variants possibly associated with dual-active anti-HIV/HBV therapy.

Antigen-presenting cell candidates for HIV-1 transmission in human distal colonic mucosa defined by CD207 dendritic cells and CD209 macrophages

A common route for HIV-1 infection is sexual transmission across colorectal mucosa, which is thought to be 10-2,000 times more vulnerable to infection than that of the female genital tract. Mucosal surfaces are the first line of defense against many pathogens but the antigen-presenting cells (APCs), key regulators of innate immunity and determinants of adaptive immunity, are not well defined in these target tissues. Using immunohistochemistry, dendritic cells expressing Langerin (CD207(+)), a lectin known to bind and internalize HIV-1, were detected in the periphery of colonic glands and sparsely scattered in the submucosa similarly in colorectal mucosa. This cell type, well known in skin, has generally not been reported in colonic/rectal mucosa. Unexpectedly, the largest APC population observed was a macrophage-like population expressing the well-characterized tissue macrophage markers CD68 and CD163. Confocal microscopy of these cells revealed colocalization of CD209 (DC-SIGN), a presumed dendritic cell marker believed to facilitate HIV-1 transmission, but not other dendritic cell markers. These results show evidence of the unconfirmed presence of Langerhans cells in colorectal mucosa and a predominance of macrophage-like APCs that express CD209 (DC-SIGN). These findings define potential target cells in the pathogenesis of HIV-1 transmission, which may have key implications for the study of early transmission events in normal colorectal mucosa, as well as other infectious diseases and primary immune diseases involving the gut.

Analysis of multiply spliced transcripts in lymphoid tissue reservoirs of rhesus macaques infected with RT-SHIV during HAART

Highly active antiretroviral therapy (HAART) can reduce levels of human immunodeficiency virus type 1 (HIV-1) to undetectable levels in infected individuals, but the virus is not eradicated. The mechanisms of viral persistence during HAART are poorly defined, but some reservoirs have been identified, such as latently infected resting memory CD4⁺ T cells. During latency, in addition to blocks at the initiation and elongation steps of viral transcription, there is a block in the export of viral RNA (vRNA), leading to the accumulation of multiply-spliced transcripts in the nucleus. Two of the genes encoded by the multiply-spliced transcripts are Tat and Rev, which are essential early in the viral replication cycle and might indicate the state of infection in a given population of cells. Here, the levels of multiply-spliced transcripts were compared to the levels of gag-containing RNA in tissue samples from RT-SHIV-infected rhesus macaques treated with HAART. Splice site sequence variation was identified during development of a TaqMan PCR assay. Multiply-spliced transcripts were detected in gastrointestinal and lymphatic tissues, but not the thymus. Levels of multiply-spliced transcripts were lower than levels of gag RNA, and both correlated with plasma virus loads. The ratio of multiply-spliced to gag RNA was greatest in the gastrointestinal samples from macaques with plasma virus loads <50 vRNA copies per mL at necropsy. Levels of gag RNA and multiply-spliced mRNA in tissues from RT-SHIV-infected macaques correlate with plasma virus load.

A comparison of methods for measuring rectal HIV levels suggests that HIV DNA resides in cells other than CD4+ T cells, including myeloid cells

We compared different techniques for measuring gut HIV reservoirs and assessed for HIV in non-CD4 T cells. HIV DNA levels were similar when measured from rectal biopsies and isolated rectal cells, while HIV RNA tended to be higher in rectal cells. HIV DNA levels in total rectal cells were greater than those predicted from levels in sorted CD4 T cells, suggesting a reservoir in non-CD4 T cells, and HIV DNA was detected in sorted myeloid cells (7/7 subjects).

Mucosal immunology of HIV infection

Recent advances in the immunology, pathogenesis, and prevention of human immunodeficiency virus (HIV) infection continue to reveal clues to the mechanisms involved in the progressive immunodeficiency attributed to infection, but more importantly have shed light on the correlates of immunity to infection and disease progression. HIV selectively infects, eliminates, and/or dysregulates several key cells of the human immune system, thwarting multiple arms of the host immune response, and inflicting severe damage to mucosal barriers, resulting in tissue infiltration of 'symbiotic' intestinal bacteria and viruses that essentially become opportunistic infections promoting systemic immune activation. This leads to activation and recruitment or more target cells for perpetuating HIV infection, resulting in persistent, high-level viral replication in lymphoid tissues, rapid evolution of resistant strains, and continued evasion of immune responses. However, vaccine studies and studies of spontaneous controllers are finally providing correlates of immunity from protection and disease progression, including virus-specific CD4(+) T-cell responses, binding anti-bodies, innate immune responses, and generation of antibodies with potent antibody-dependent cell-mediated cytotoxicity activity. Emerging correlates of immunity indicate that prevention of HIV infection may be possible through effective vaccine strategies that protect and stimulate key regulatory cells and immune responses in susceptible hosts. Furthermore, immune therapies specifically directed toward boosting specific aspects of the immune system may eventually lead to a cure for HIV-infected patients.

The HIV-1 reservoir in eight patients on long-term suppressive antiretroviral therapy is stable with few genetic changes over time

The source and dynamics of persistent HIV-1 during long-term combinational antiretroviral therapy (cART) are critical to understanding the barriers to curing HIV-1 infection. To address this issue, we isolated and genetically characterized HIV-1 DNA from naïve and memory T cells from peripheral blood and gut-associated lymphoid tissue (GALT) from eight patients after 4-12 y of suppressive cART. Our detailed analysis of these eight patients indicates that persistent HIV-1 in peripheral blood and GALT is found primarily in memory CD4(+) T cells [CD45RO(+)/CD27((+/-))]. The HIV-1 infection frequency of CD4(+) T cells from peripheral blood and GALT was higher in patients who initiated treatment during chronic compared with acute/early infection, indicating that early initiation of therapy results in lower HIV-1 reservoir size in blood and gut. Phylogenetic analysis revealed an HIV-1 genetic change between RNA sequences isolated before initiation of cART and intracellular HIV-1 sequences from the T-cell subsets after 4-12 y of suppressive cART in four of the eight patients. However, evolutionary rate analyses estimated no greater than three nucleotide substitutions per gene region analyzed during all of the 4-12 y of suppressive therapy. We also identified a clearly replication-incompetent viral sequence in multiple memory T cells in one patient, strongly supporting asynchronous cell replication of a cell containing integrated HIV-1 DNA as the source. This study indicates that persistence of a remarkably stable population of infected memory cells will be the primary barrier to a cure, and, with little evidence of viral replication, this population could be maintained by homeostatic cell proliferation or other processes.

Dolutegravir pharmacokinetics in the genital tract and colorectum of HIV-negative men after single and multiple dosing

OBJECTIVES

To describe first-dose and steady state pharmacokinetics (PKs) of dolutegravir (DTG) in blood plasma (BP), seminal fluid (SF), colorectal tissue (RT), and rectal mucosal fluid (RF) of healthy HIV-negative men.

DESIGN

A phase 1, open-label, PK study that enrolled 12 healthy men taking 50 mg DTG daily for 8 days.

METHODS

Eleven paired BP samples and 3 SF and RF samples were collected over 24 hours after first (PK1) and multiple (PK2) dosing. RT biopsies were collected at 1 of 6 time points at PK1 and PK2 to generate composite PK profiles. DTG concentrations were analyzed by validated liquid chromatography-tandem mass spectrometry (LC-MS/MS). Noncompartmental PK analysis was conducted with Phoenix WinNonlin v6.3, and Spearman rank correlations were determined using SAS v9.3.

RESULTS

BP area under the concentration-time curves (AUCs) were similar to previous reports, and concentrations at 24 hours (C24 h) were 6- to 34-fold greater than the protein-adjusted concentration required for 90% viral inhibition (PA-IC90) of 64 ng/mL. SF exposures were <7% of BP and below the PA-IC90. RT exposures were 17% of BP and ∼2-fold greater than the PA-IC90. RF AUCs were ∼2%-5% of RT and did not correlate with RT (rho = 0.43, P = 0.17). Accumulation of DTG with multiple dosing was observed in BP, SF, and RT.

CONCLUSIONS

DTG BP PKs were consistent with previously published values. SF concentrations were <7% BP, with SF C24 h below the PA-IC90. However, SF protein binding was not measured. Although the AUC of DTG in RT was <20% BP, RT C24 h remained ∼2-fold higher than the PA-IC90. RF was not a strong surrogate for RT concentrations.