Strategies to target the central nervous system HIV reservoir

PURPOSE OF THE REVIEW

The central nervous system (CNS) is an hotspot for HIV persistence and may be a major obstacle to overcome for curative strategies. The peculiar anatomical, tissular and cellular characteristics of the HIV reservoir in the CNS may need to be specifically addressed to achieve a long-term HIV control without ART. In this review, we will discuss the critical challenges that currently explored curative strategies may face in crossing the blood-brain barrier (BBB), targeting latent HIV in brain-resident myeloid reservoirs, and eliminating the virus without eliciting dangerous neurological adverse events.

RECENT FINDINGS

Latency reversing agents (LRA), broadly neutralizing monoclonal antibodies (bNabs), chimeric antigen receptor (CAR) T-cells, and adeno-associated virus 9-vectored gene-therapies cross the BBB with varying efficiency. Although brain penetration is poor for bNAbs, viral vectors for in vivo gene-editing, certain LRAs, and CAR T-cells may reach the cerebral compartment more efficiently. All these approaches, however, may encounter difficulties in eliminating HIV-infected perivascular macrophages and microglia. Safety, including local neurological adverse effects, may also be a concern, especially if high doses are required to achieve optimal brain penetration and efficient brain cell targeting.

SUMMARY

Targeting the CNS remains a potential problem for the currently investigated HIV curing strategies. In vivo evidence on CNS effectiveness is limited for most of the investigated strategies, and additional studies should be focused on evaluating the interplay between the cerebral HIV reservoir and treatment aiming to achieve an ART-free cure.

A Randomised Clinical Trial of the Safety and Pharmacokinetics of VRC07-523LS Administered via Different Routes and Doses (HVTN 127/HPTN 087)

Background

Broadly neutralizing antibodies (bnAbs) are a promising approach for HIV-1 prevention. In the only bnAb HIV prevention efficacy studies to date, the Antibody Mediated Prevention (AMP) trials, a CD4-binding site targeting bnAb, VRC01, administered intravenously (IV), demonstrated 75% prevention efficacy against highly neutralization-sensitive viruses but was ineffective against less sensitive viruses. Greater efficacy is required before passively administered bnAbs become a viable option for HIV prevention; furthermore subcutaneous (SC) or intramuscular (IM) administration may be preferred. VRC07-523LS is a next-generation bnAb targeting the CD4-binding site and was engineered for increased neutralization breadth and half-life.

Methods

Participants were recruited between 02 February 2018 and 09 October 2018. 124 healthy participants without HIV were randomized to receive five VRC07-523LS administrations via IV (T1: 2.5 mg/kg, T2: 5 mg/kg, T3: 20 mg/kg), SC (T4: 2.5 mg/kg, T5: 5 mg/kg) or IM (T6: 2.5 mg/kg or P6: placebo) routes at four-month intervals. Safety data were collected for 144 weeks following the first administration. VRC07-523LS serum concentrations were measured by ELISA after the first dose through Day 112 in all participants and by binding antibody multiplex assay (BAMA) thereafter in 60 participants (10 per treatment group) through Day 784. Compartmental population pharmacokinetic (PK) analyses were conducted to evaluate the VRC07-523LS serum pharmacokinetics. Neutralization activity was measured in a TZM-bl assay and anti-drug antibodies (ADA) were assayed using a tiered bridging assay testing strategy.

Results

Injections were well-tolerated, with mild pain or tenderness reported commonly in the SC and IM groups, and mild to moderate erythema or induration reported commonly in the SC groups. Infusions were generally well-tolerated, with infusion reactions reported in 3 of 20 participants in the 20 mg/kg IV group. Peak geometric mean (GM) concentrations (95% confidence intervals) following the first administration were 29.0 μg/mL (25.2, 33.4), 58.5 μg/mL (49.4, 69.3), and 257.2 μg/mL (127.5, 518.9) in T1-T3 with IV dosing; 10.8 μg/mL (8.8, 13.3) and 22.8 μg/mL (20.1, 25.9) in T4-T5 with SC dosing; and 16.4 μg/mL (14.7, 18.2) in T6 with IM dosing. Trough GM concentrations immediately prior to the second administration were 3.4 μg/mL (2.5, 4.6), 6.5 μg/mL (5.6, 7.5), and 27.2 μg/mL (23.9, 31.0) with IV dosing; 0.97 μg/mL (0.65, 1.4) and 3.1 μg/mL (2.2, 4.3) with SC dosing, and 2.6 μg/mL (2.05, 3.31) with IM dosing. Peak VRC07-523LS serum concentrations increased linearly with the administered dose. At a given dose, peak and trough concentrations, as well as serum neutralization titres, were highest in the IV groups, reflecting the lower bioavailability following SC and IM administration. A single participant was found to have low titre ADA at a lone timepoint. VRC07-523LS has an estimated mean half-life of 42 days (95% CI: 40.5, 43.5), approximately twice as long as VRC01.

Conclusions

VRC07-523LS was safe and well-tolerated across a range of doses and routes and is a promising long-acting bnAb for inclusion in HIV-1 prevention regimens.

Adults on pre-exposure prophylaxis (tenofovir-emtricitabine) have faster clearance of anti-HIV monoclonal antibody VRC01

Broadly neutralizing monoclonal antibodies (mAbs) are being developed for HIV-1 prevention. Hence, these mAbs and licensed oral pre-exposure prophylaxis (PrEP) (tenofovir-emtricitabine) can be concomitantly administered in clinical trials. In 48 US participants (men and transgender persons who have sex with men) who received the HIV-1 mAb VRC01 and remained HIV-free in an antibody-mediated-prevention trial (ClinicalTrials.gov #NCT02716675), we conduct a post-hoc analysis and find that VRC01 clearance is 0.08 L/day faster (p = 0.005), and dose-normalized area-under-the-curve of VRC01 serum concentration over-time is 0.29 day/mL lower (p < 0.001) in PrEP users (n = 24) vs. non-PrEP users (n = 24). Consequently, PrEP users are predicted to have 14% lower VRC01 neutralization-mediated prevention efficacy against circulating HIV-1 strains. VRC01 clearance is positively associated (r = 0.33, p = 0.03) with levels of serum intestinal Fatty Acid Binding protein (I-FABP), a marker of epithelial intestinal permeability, which is elevated upon starting PrEP (p = 0.04) and after months of self-reported use (p = 0.001). These findings have implications for the evaluation of future HIV-1 mAbs and postulate a potential mechanism for mAb clearance in the context of PrEP.

Safety, tolerability, pharmacokinetics, and immunological activity of dual-combinations and triple-combinations of anti-HIV monoclonal antibodies PGT121, PGDM1400, 10-1074, and VRC07-523LS administered intravenously to HIV-uninfected adults: a phase 1 randomised trial

BACKGROUND

Preclinical and clinical studies suggest that combinations of broadly neutralising antibodies (bnAbs) targeting different HIV envelope epitopes might be required for sufficient prevention of infection. We aimed to evaluate the dual and triple anti-HIV bnAb combinations of PGDM1400 (V2 Apex), PGT121 (V3 glycan), 10-1074 (V3 glycan), and VRC07-523LS (CD4 binding site).

METHODS

In this phase 1 trial (HVTN 130/HPTN 089), adults without HIV were randomly assigned (1:1:1) to three dual-bnAb treatment groups simultaneously, or the triple-bnAb group, receiving 20 mg/kg of each antibody administered intravenously at four centres in the USA. Participants received a single dose of PGT121 + VRC07-523LS (treatment one; n=6), PGDM1400 + VRC07-523LS (treatment two; n=6), or 10-1074 + VRC07-523LS (treatment three; n=6), and two doses of PGDM1400 + PGT121 + VRC07-523LS (treatment four; n=9). Primary outcomes were safety, pharmacokinetics, and neutralising activity. Safety was determined by monitoring for 60 min after infusions and throughout the study by collecting laboratory assessments (ie, blood count, chemistry, urinalysis, and HIV), and solicited and unsolicited adverse events (via case report forms and participant diaries). Serum concentrations of each bnAb were measured by binding antibody assays on days 0, 3, 6, 14, 28, 56, 112, 168, 224, 280, and 336, and by serum neutralisation titres against Env-pseudotyped viruses on days 0, 3, 28, 56, and 112. Pharmacokinetic parameters were estimated by use of two-compartment population pharmacokinetic models; combination bnAb neutralisation titres were directly measured and assessed with different interaction models. This trial is registered with ClinicalTrials.gov, NCT03928821, and has been completed.

FINDINGS

27 participants were enrolled from July 31, to Dec 20, 2019. The median age was 26 years (range 19-50), 16 (58%) of 27 participants were assigned female sex at birth, and 24 (89%) participants were non-Hispanic White. Infusions were safe and well tolerated. There were no statistically significant differences in pharmacokinetic patterns between the dual and triple combinations of PGT121, PGDM1400, and VRC07-523LS. The median estimated elimination half-lives of PGT121, PGDM1400, 10-1074, and VRC07-523LS were 32·2, 25·4, 27·5, and 52·9 days, respectively. Neutralisation coverage against a panel of 12 viruses was greater in the triple-bnAb versus dual-bnAb groups: area under the magnitude-breadth curve at day 28 was 3·1, 2·9, 3·0, and 3·4 for treatments one to four, respectively. The Bliss-Hill multiplicative interaction model, which assumes complementary neutralisation with no antagonism or synergism among the bnAbs, best described combination bnAb titres in the dual-bnAb and triple-bnAb groups.

INTERPRETATION

No pharmacokinetic interactions among the bnAbs and no loss of complementary neutralisation were observed in the dual and triple combinations. This study lays the foundation for designing future combination bnAb HIV prevention efficacy trials.

FUNDING

US National Institute of Allergy and Infectious Diseases, US National Institute on Drug Abuse, US National Institute of Mental Health, and the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Extended safety and tolerability of subcutaneous CAP256V2LS and VRC07-523LS in HIV-negative women: study protocol for the randomised, placebo-controlled double-blinded, phase 2 CAPRISA 012C trial

INTRODUCTION

Women-controlled HIV prevention technologies that overcome adherence challenges of available daily oral pre-exposure prophylaxis and give women a choice of options are urgently needed. Broadly neutralising monoclonal antibodies (bnAbs) administered passively may offer a valuable non-antiretroviral biological intervention for HIV prevention. Animal and human studies have demonstrated that bnAbs which neutralise HIV can prevent infection. The optimal plasma antibody concentrations to confer protection against HIV infection in humans is under intense study. The Centre for the AIDS Programme of Research in South Africa (CAPRISA) 012C trial will evaluate extended safety and pharmacokinetics of CAP256V2LS and VRC07-523LS among young HIV-negative South African and Zambian women. The study design also allows for an evaluation of a signal of HIV prevention efficacy.

METHODS AND ANALYSIS

CAPRISA 012 is a series of trials with three distinct protocols. The completed CAPRISA 012A and 012B phase 1 trials provided critical data for the CAPRISA 012C trial, which is divided into parts A and B. In part A, 90 participants were randomised to receive both CAP256V2LS and VRC07-523LS at 20 mg/kg or placebo, subcutaneously every 16 or 24 weeks. Part B will enrol 900 participants in South Africa and Zambia who will be randomised in a 1:1 ratio and receive an initial loading dose of 1.2 g of CAP256V2LS and VRC07-523LS or placebo followed by 600 mg of CAP256V2LS and 1.2 g of VRC07-523LS or placebo subcutaneously every 6 months. Safety will be assessed by frequency and severity of reactogenicity and other related adverse events. Pharmacokinetics of both antibodies will be measured in systemic and mucosal compartments over time, while participants will be monitored for breakthrough HIV infections.

ETHICS AND DISSEMINATION OF STUDY FINDINGS

The University of KwaZulu-Natal Biomedical Research Ethics Committee and South African Health Products Regulatory Authority have approved the trial (BREC/00002492/2021, SAHPRA20210317). Results will be disseminated through conference presentations, peer-reviewed publications and the clinical trial registry.

TRIAL REGISTRATION NUMBER

PACTR202112683307570.

Broadly neutralizing antibody treatment maintained HIV suppression in children with favorable reservoir characteristics in Botswana

Broadly neutralizing antibodies (bNAbs) may provide an alternative to standard antiretroviral treatment (ART) for controlling HIV-1 replication and may have immunotherapeutic effects against HIV-1 reservoirs. We conducted a prospective clinical trial with two HIV-1 bNAbs (VRC01LS and 10-1074) in children (n = 25) who had previously initiated small-molecule ART treatment before 7 days of age and who continued treatment for at least 96 weeks. Both bNAbs were dosed intravenously every 4 weeks, overlapping with ART for at least 8 weeks and then continued for up to 24 weeks or until detectable viremia of HIV-1 RNA rose above 400 copies per milliliter in the absence of ART. Eleven (44%) children maintained HIV-1 RNA below 400 copies per milliliter through 24 weeks of bNAb-only treatment; 14 (56%) had detectable viremia above 400 copies per milliliter at a median of 4 weeks. Archived HIV-1 provirus susceptible to 10-1074, lower birth HIV-1 DNA reservoir in peripheral blood mononuclear cells, sustained viral suppression throughout early life, and combined negative qualitative HIV-1 DNA polymerase chain reaction and negative HIV-1 serology at entry were associated with maintaining suppression on bNAbs alone. This proof-of-concept study suggests that bNAbs may represent a promising treatment modality for infants and children living with HIV-1. Future studies using newer bNAb combinations with greater breadth and potency are warranted.

Monocyte-derived macrophages contain persistent latent HIV reservoirs

The development of persistent cellular reservoirs of latent human immunodeficiency virus (HIV) is a critical obstacle to viral eradication since viral rebound takes place once anti-retroviral therapy (ART) is interrupted. Previous studies show that HIV persists in myeloid cells (monocytes and macrophages) in blood and tissues in virologically suppressed people with HIV (vsPWH). However, how myeloid cells contribute to the size of the HIV reservoir and what impact they have on rebound after treatment interruption remain unclear. Here we report the development of a human monocyte-derived macrophage quantitative viral outgrowth assay (MDM-QVOA) and highly sensitive T cell detection assays to confirm purity. We assess the frequency of latent HIV in monocytes using this assay in a longitudinal cohort of vsPWH (n = 10, 100% male, ART duration 5-14 yr) and find half of the participants showed latent HIV in monocytes. In some participants, these reservoirs could be detected over several years. Additionally, we assessed HIV genomes in monocytes from 30 vsPWH (27% male, ART duration 5-22 yr) utilizing a myeloid-adapted intact proviral DNA assay (IPDA) and demonstrate that intact genomes were present in 40% of the participants and higher total HIV DNA correlated with reactivatable latent reservoirs. The virus produced in the MDM-QVOA was capable of infecting bystander cells resulting in viral spread. These findings provide further evidence that myeloid cells meet the definition of a clinically relevant HIV reservoir and emphasize that myeloid reservoirs should be included in efforts towards an HIV cure.

Rhesus macaque Bcl-6/Bcl-xL B cell immortalization: Discovery of HIV-1 neutralizing antibodies from lymph node

Many HIV-1 vaccines are designed to elicit neutralizing antibodies, and pre-clinical testing is often carried out in rhesus macaques (RMs). We have therefore adapted a method of B cell immortalization for use with RM B cells. In this system, RM B cells are activated with CD40 ligand and RM IL-21 before transduction with a retroviral vector encoding Bcl-6, Bcl-xL, and green fluorescent protein. Importantly, RM B cells from lymph nodes are more effectively immortalized by this method than B cells from PBMC, a difference not seen in humans. We suggest the discrepancy between these two tissues is due to increased expression of CD40 on RM lymph node B cells. Immortalized RM B cells expand long-term, undergo minimal somatic hypermutation, express surface B cell receptor, and secrete antibodies into culture. This allows for the identification of cells based on antigen specificity and/or functional assays. Here, we show the characterization of this system and its application for the isolation of HIV-1 neutralizing antibodies from a SHIV.CH505-infected animal, both with and without antigen probe. Taken together, we show that Bcl-6/xL immortalization is a valuable and flexible tool for antibody discovery in RMs, but with important distinctions from application of the system in human cells.

Application of B cell immortalization for the isolation of antibodies and B cell clones from vaccine and infection settings

The isolation and characterization of neutralizing antibodies from infection and vaccine settings informs future vaccine design, and methodologies that streamline the isolation of antibodies and the generation of B cell clones are of great interest. Retroviral transduction to express Bcl-6 and Bcl-xL and transform primary B cells has been shown to promote long-term B cell survival and antibody secretion in vitro, and can be used to isolate antibodies from memory B cells. However, application of this methodology to B cell subsets from different tissues and B cells from chronically infected individuals has not been well characterized. Here, we characterize Bcl-6/Bcl-xL B cell immortalization across multiple tissue types and B cell subsets in healthy and HIV-1 infected individuals, as well as individuals recovering from malaria. In healthy individuals, naïve and memory B cell subsets from PBMCs and tonsil tissue transformed with similar efficiencies, and displayed similar characteristics with respect to their longevity and immunoglobulin secretion. In HIV-1-viremic individuals or in individuals with recent malaria infections, the exhausted CD27^-CD21^- memory B cells transformed with lower efficiency, but the transformed B cells expanded and secreted IgG with similar efficiency. Importantly, we show that this methodology can be used to isolate broadly neutralizing antibodies from HIV-infected individuals. Overall, we demonstrate that Bcl-6/Bcl-xL B cell immortalization can be used to isolate antibodies and generate B cell clones from different B cell populations, albeit with varying efficiencies.

Engineering of HIV-1 neutralizing antibody CAP256V2LS for manufacturability and improved half life

The broadly neutralizing antibody (bNAb) CAP256-VRC26.25 has exceptional potency against HIV-1 and has been considered for clinical use. During the characterization and production of this bNAb, we observed several unusual features. First, the antibody appeared to adhere to pipette tips, requiring tips to be changed during serial dilution to accurately measure potency. Second, during production scale-up, proteolytic cleavage was discovered to target an extended heavy chain loop, which was attributed to a protease in spent medium from 2-week culture. To enable large scale production, we altered the site of cleavage via a single amino acid change, K100mA. The resultant antibody retained potency and breadth while avoiding protease cleavage. We also added the half-life extending mutation LS, which improved the in vivo persistence in animal models, but did not impact neutralization activity; we observed the same preservation of neutralization for bNAbs VRC01, N6, and PGDM1400 with LS on a 208-virus panel. The final engineered antibody, CAP256V2LS, retained the extraordinary neutralization potency of the parental antibody, had a favorable pharmacokinetic profile in animal models, and was negative in in vitro assessment of autoreactivity. CAP256V2LS has the requisite potency, developability and suitability for scale-up, allowing its advancement as a clinical candidate.

Safety and Pharmacokinetics of Intravenous 10-1074 and VRC01LS in Young Children

BACKGROUND

Broadly neutralizing monoclonal antibodies (bNAbs) suppress HIV-1 RNA and may deplete residual viral reservoirs. We evaluated the safety and pharmacokinetics (PK) of dual intravenous VRC01LS and 10-1074 in very early-treated children with HIV-1 on suppressive antiretroviral treatment (ART).

SETTING

Botswana.

METHODS

Children with HIV-1 (median age 3.1 years) on ART from <7 days old were enrolled. In phase A, 6 children received 10-1074 (30 mg/kg at day 0, 28, and 56) and 6 children received VRC01LS (30 mg/kg at day 0, 10 mg/kg at days 28 and 56) by intravenous infusion. In phase B, 6 children received the 2 bNAbs combined (with higher VRC01LS maintenance dose, 15 mg/kg) every 4 weeks for 32 weeks with PK evaluations over 8 weeks. Population PK models were developed to predict steady-state concentrations.

RESULTS

BNAb infusions were well tolerated. There were no infusion reactions nor any bNAb-related grade 3 or 4 events. The median (range) first dose Cmax and trough (day 28) combined from both phases were 1405 (876-1999) μg/mL and 133 (84-319) μg/mL for 10-1074 and 776 (559-846) μg/mL and 230 (158-294) μg/mL for VRC01LS. No large differences in bNAb clearances were observed when given in combination. The estimated VRC01LS half-life was shorter than in adults. Predicted steady-state troughs [median (90% prediction interval)] were 261 (95-565) and 266 (191-366) μg/mL for 10-1074 and VRC01LS, respectively, when given in combination.

CONCLUSIONS

10-1074 and VRC01LS were safe and well-tolerated among children receiving ART. Troughs exceeded minimal targets with every 4-week administration of 10-1074 at 30 mg/kg and VRC01LS at 15 mg/kg.

Effect of Single Housing on Innate Immune Activation in Immunodeficiency Virus-Infected Pigtail Macaques ( Macaca nemestrina ) as a Model of Psychosocial Stress in Acute HIV Infection

OBJECTIVE

Simian immunodeficiency virus (SIV) infection of macaques recapitulates many aspects of HIV pathogenesis and is similarly affected by both genetic and environmental factors. Psychosocial stress is associated with immune system dysregulation and worse clinical outcomes in people with HIV. This study assessed the impact of single housing, as a model of psychosocial stress, on innate immune responses of pigtailed macaques ( Macaca nemestrina ) during acute SIV infection.

METHODS

A retrospective analysis of acute SIV infection of 2- to si6-year-old male pigtailed macaques was performed to compare the innate immune responses of socially ( n = 41) and singly ( n = 35) housed animals. Measures included absolute monocyte count and subsets, and in a subset ( n ≤ 18) platelet counts and activation data.

RESULTS

SIV infection resulted in the expected innate immune parameter changes with a modulating effect from housing condition. Monocyte number increased after infection for both groups, driven by classical monocytes (CD14 + CD16 - ), with a greater increase in socially housed animals (227%, p < .001, by day 14 compared with preinoculation time points). Platelet numbers recovered more quickly in the socially housed animals. Platelet activation (P-selectin) increased by 65% ( p = .004) and major histocompatibility complex class I surface expression by 40% ( p = .009) from preinoculation only in socially housed animals, whereas no change in these measures occurred in singly housed animals.

CONCLUSIONS

Chronic psychosocial stress produced by single housing may play an immunomodulatory role in the innate immune response to acute retroviral infection. Dysregulated innate immunity could be one of the pathways by which psychosocial stress contributes to immune suppression and increased disease severity in people with HIV.

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.

Stable Latent HIV Infection and Low-level Viremia Despite Treatment With the Broadly Neutralizing Antibody VRC07-523LS and the Latency Reversal Agent Vorinostat

We tested the combination of a broadly neutralizing HIV antibody with the latency reversal agent vorinostat (VOR). Eight participants received 2 month-long cycles of VRC07-523LS with VOR. Low-level viremia, resting CD4+ T-cell-associated HIV RNA (rca-RNA) was measured, and intact proviral DNA assay (IPDA) and quantitative viral outgrowth assay (QVOA) were performed at baseline and posttreatment. In 3 participants, IPDA and QVOA declines were accompanied by significant declines of rca-RNA. However, no IPDA or QVOA declines clearly exceeded assay variance or natural decay. Increased resistance to VRC07-523LS was not observed. This combination therapy did not reduce viremia or the HIV reservoir. Clinical Trials Registration. NCT03803605.

Quantitative Viral Outgrowth Assay to Measure the Functional SIV Reservoir in Myeloid Cells

The role of CD4+ T cells in HIV infection and the latent reservoir, that is, latently infected cells that harbor replication competent virus, has been rigorously assessed. We have previously reported a quantitative viral outgrowth assay (QVOA) for SIV that demonstrated the frequency of latently infected CD4+ T cells is approximately 1 in a million cells, similar to that of HIV infected individuals on ART. However, the frequency of productively infected monocytes in blood and macrophages in tissues has not been similarly studied. Myeloid cells are infected during acute HIV and SIV infection; however, unlike lymphocytes, they are resistant to the cytopathic effects of the virus. Moreover, tissue-resident macrophages have the ability to self-renew and persist in the body for months to years. Thus, tissue macrophages, once infected, have the characteristics of a stable viral reservoir. A better understanding of the number of productively infected macrophages is critical to understanding the role of infected myeloid cells as a viral reservoir. In order to assess the functional latent reservoir. we have developed specific QVOAs for monocytes in blood, and macrophages in spleen, BAL and brain, which are described in detail in this chapter.

Predictors of patient and system delay for primary percutaneous coronary intervention

Background

The delay times of the patient and the system for primary percutaneous coronary intervention (p-PCI) have a determining impact on the prognosis of patients with acute myocardial infarction with ST segment elevation (STEMI).

Purpose

To identify the predictors of patient and system delay for p-PCI in the period of 2020 at a reference hospital for p-PCI.

Methods

Patients submitted to p-PCI in the period from March to September 2020 were included and compared with the same period in 2019. We analyzed the differences between the two groups regarding the patient's delay times, time from the onset of symptoms to the first medical contact (FCM) and the system (time from the first contact with the health system to p-ICP). Data collection of the patient's previous history, coronary intervention performed and post-PCI follow-up was performed using the electronic patient record. Univariate analysis and logistic regression models from multivariate analysis were used to determine the predictors of “patient delay” and “system delay” and adjusted for confounding factors. The analysis was performed with a significance level of 5%.

Results

We included in the study 255 patients who underwent p-PCI, of which 122 in the period from 2020 and 133 in the period from 2019. Regarding the characteristics of the population, there were no significant differences between the two periods. Regarding the patient's delay time, there were no statistically significant differences. The variable first medical contact with a non p-PCI center was the only variable associated with system delay&gt;90 minutes in the multivariate analysis, OR (6.18: 95% CI, 1.91–20), p=0.002. There was a statistically significant association between the period of 2020 (pandemic period) and total ischemia time, but with a negative effect, dependent variable adjusted for confounding factors [adjusted OR: −0.10; 95% CI: −107.61 to −5.57; p=0.03].

Conclusion

In this study, the patient's admission to a non p-PCI centers was identified as the only predictor of longer delay until p-PCI (system delay). However, these results should serve as a contribution to decision making in order to mitigate risks, regardless of any associated catastrophe and eventually alert the population not to neglect the symptoms suspected of acute myocardial infarction.

Funding Acknowledgement

Type of funding sources: None.

Concordance of immunological events between intrarectal and intravenous SHIVAD8-EO infection when assessed by Fiebig-equivalent staging

Primary HIV-1 infection can be classified into six Fiebig stages based on virological and serological laboratory testing, whereas simian-HIV (SHIV) infection in nonhuman primates (NHPs) is defined in time post-infection, making it difficult to extrapolate NHP experiments to the clinics. We identified and extensively characterized the Fiebig-equivalent stages in NHPs challenged intrarectally or intravenously with SHIVAD8-EO. During the first month post-challenge, intrarectally challenged monkeys were up to 1 week delayed in progression through stages. However, regardless of the challenge route, stages I-II predominated before, and stages V-VI predominated after, peak viremia. Decrease in lymph node (LN) CD4+ T cell frequency and rise in CD8+ T cells occurred at stage V. LN virus-specific CD8+ T cell responses, dominated by degranulation and TNF, were first detected at stage V and increased at stage VI. A similar late elevation in follicular CXCR5+ CD8+ T cells occurred, consistent with higher plasma CXCL13 levels at these stages. LN SHIVAD8-EO RNA+ cells were present at stage II, but appeared to decline at stage VI when virions accumulated in follicles. Fiebig-equivalent staging of SHIVAD8-EO infection revealed concordance of immunological events between intrarectal and intravenous infection despite different infection progressions, and can inform comparisons of NHP studies with clinical data.

Psychosocial Stress Alters the Immune Response and Results in Higher Viral Load During Acute SIV Infection in a Pigtailed Macaque Model of HIV

BACKGROUND

While social distancing is a key public health response during viral pandemics, psychosocial stressors, such as social isolation, have been implicated in adverse health outcomes in general (1) and in the context of infectious disease, such as HIV (2,3). A comprehensive understanding of the direct pathophysiologic effects of psychosocial stress on viral pathogenesis is needed to provide strategic and comprehensive care to patients with viral infection.

METHODS

To determine the effect of psychosocial stress on HIV pathogenesis during acute viral infection without sociobehavioral confounders inherent in human cohorts, we compared commonly measured parameters of HIV progression between singly (n=35) and socially (n=41) housed SIV-infected pigtailed macaques (Macaca nemestrina).

RESULTS

Singly housed macaques had a higher viral load in the plasma and cerebrospinal fluid and demonstrated greater CD4 T cell declines and more CD4 and CD8 T cell activation compared to socially housed macaques throughout acute SIV infection.

CONCLUSIONS

These data demonstrate that psychosocial stress directly impacts the pathogenesis of acute SIV infection and imply that it may act as an integral variable in the progression of HIV infection and potentially of other viral infections.

HIV replication and latency in monocytes and macrophages

The relevance of monocyte and macrophage reservoirs in virally suppressed people with HIV (vsPWH) has previously been debatable. Macrophages were assumed to have a moderate life span and lack self-renewing potential. However, recent studies have challenged this dogma and now suggest an important role of these cell as long-lived HIV reservoirs. Lentiviruses have a long-documented association with macrophages and abundant evidence exists that macrophages are important target cells for HIV in vivo. A critical understanding of HIV infection, replication, and latency in macrophages is needed in order to determine the appropriate method of measuring and eliminating this cellular reservoir. This review provides a brief discussion of the biology and acute and chronic infection of monocytes and macrophages, with a more substantial focus on replication, latency and measurement of the reservoir in cells of myeloid origin.

Model Informed Development of VRC01 in Newborn Infants Using a Population Pharmacokinetics Approach

VRC01 is a first-in-class, potent, broadly neutralizing antibody that targets the CD4 binding site of gp120 on HIV-1 viruses, and is under development as a novel HIV therapeutic. This study utilized population pharmacokinetic (PK) modeling to characterize VRC01 PK to guide dosing selection for ongoing phase II clinical trials in pediatric patients. Combining VRC01 PK data from 3 adult and 1 infant clinical trials, a total of 1,475 VRC01 serum concentrations from 100 participants were used in the analysis (40 infants and 60 adults). VRC01 was administered either i.v. or s.c. (1-40 mg/kg). All infants received s.c. doses as compared with 13% s.c. and 87% i.v. in adults. The data were well-described by a two-compartment model. Clearance was 37% higher in adults with HIV infection and 83% lower in infants than adults. Subcutaneous bioavailability was 55% in adults. Rapid absorption was seen in infants indicating therapeutic levels could be achieved quickly. Monte Carlo simulations were used to determine optimal dosing and demonstrated 40 mg/kg s.c. at weeks 0, 2, 6, and 10 would maintain VRC01 levels at the suppressive target concentration of 50 μg/mL for the first 14 weeks of life in infants. The current analysis provides new insight into differences in monoclonal antibody PK between infants and adults and demonstrates the utility of a population PK approach in informing drug development for infant populations.

Adoptive Cell Transfer of Regulatory T Cells Exacerbates Hepatic Steatosis in High-Fat High-Fructose Diet-Fed Mice

Background and Aims: Non-alcoholic steatohepatitis (NASH) is a multisystem condition, involving the liver, adipose tissue, and immune system. Regulatory T (Treg) cells are a subset of T cells that exert an immune-controlling effect. Previously, a reduction of Treg cells in the visceral adipose tissue (VAT) was shown to be associated with a more severe degree of liver disease. We aimed to correct this immune disruption through adoptive cell transfer (ACT) of Treg cells. Methods: Male 8-week-old C57BL/6J mice were fed a high-fat high-fructose diet (HFHFD) for 20 weeks. Treg cells were isolated from the spleens of healthy 8 to 10-week-old C57BL/6J mice and were adoptively transferred to HFHFD-fed mice. PBS-injected mice served as controls. Plasma ALT and lipid levels were determined. Liver and adipose tissue were assessed histologically. Cytotoxic T (Tc), Treg, T helper (Th) 1 and Th17 cells were characterized in VAT, liver, subcutaneous adipose tissue (SAT), blood, and spleen via flow cytometry. Gene expression analysis was performed in SAT and VAT of mice fed either the HFHFD or a control diet for 10-32 weeks. Results: ACT increased Treg cells in SAT, but not in any of the other tissues. Moreover, the ACT induced a decrease in Th1 cells in SAT, liver, blood, and spleen. Higher plasma ALT levels and a higher degree of steatosis were observed in ACT mice, whereas the other HFHFD-induced metabolic and histologic disruptions were unaffected. Expression analysis of genes related to Treg-cell proliferation revealed a HFHFD-induced decrease in all investigated genes in the SAT, while in the VAT the expression of these genes was largely unaffected, except for a decrease in Pparg. Conclusion: ACT of Treg cells in HFHFD-fed mice exacerbated hepatic steatosis, which was possibly related to the increase of Treg cells in the SAT and/or the general decrease in Th1 cells. Moreover, the HFHFD-induced decrease in Pparg expression appeared critical in the decrease of Treg cells at the level of the VAT and the inability to replenish the amount of Treg cells by the ACT, while the mechanism of Treg cell accumulation at the level of the SAT remained unclear.

Diet Reversal and Immune Modulation Show Key Role for Liver and Adipose Tissue T Cells in Murine Nonalcoholic Steatohepatitis

BACKGROUND & AIMS

Nonalcoholic steatohepatitis (NASH) is a multisystem condition, implicating liver and adipose tissue. Although the general involvement of the innate and adaptive immune system has been established, we aimed to define the exact role of the functionally diverse T-cell subsets in NASH pathogenesis through diet reversal and immunologic modulation.

METHODS

Multiple experimental set-ups were used in 8-week-old C57BL/6J mice, including prolonged high-fat high-fructose diet (HFHFD) feeding, diet reversal from HFHFD to control diet, and administration of anti-CD8a and anti-interleukin 17A antibodies. Plasma alanine aminotransferase, glucose, and lipid levels were determined. Liver and adipose tissue were assessed histologically. Cytotoxic T (Tc), regulatory T, T helper (Th) 1, and Th17 cells were characterized in liver and visceral adipose tissue (VAT) via flow cytometry and RNA analysis.

RESULTS

HFHFD feeding induced the metabolic syndrome and NASH, which coincided with an increase in hepatic Th17, VAT Tc, and VAT Th17 cells, and a decrease in VAT regulatory T cells. Although diet reversal induced a phenotypical metabolic and hepatic normalization, the observed T-cell disruptions persisted. Treatment with anti-CD8a antibodies decreased Tc cell numbers in all investigated tissues and induced a biochemical and histologic attenuation of the HFHFD-induced NASH. Conversely, anti-interleukin 17A antibodies decreased hepatic inflammation without affecting other features of NASH or the metabolic syndrome.

CONCLUSIONS

HFHFD feeding induces important immune disruptions in multiple hepatic and VAT T-cell subsets, refractory to diet reversal. In particular, VAT Tc cells are critically involved in NASH pathogenesis, linking adipose tissue inflammation to liver disease.

Compromised steady-state germinal center activity with age in nonhuman primates

Age-related reductions in vaccine-induced B cells in aging indicate that germinal centers (GCs), the anatomical site where the development of humoral responses takes place, may lose efficacy with age. We have investigated the baseline follicular and GC composition in nonhuman primates (NHPs) with respect to their age. There was a marked reduction in follicular area in old animals. We found significantly lower normalized numbers of follicular PD1hi CD4 T (Tfh) and proliferating (Ki67hi ) GC B cells with aging, a profile associated with significantly higher numbers of potential follicular suppressor FoxP3hi Lag3hi CD4 T cells. Furthermore, a positive correlation was found between Tfh and follicular CD8 T cells (fCD8) only in young animals. Despite the increased levels of circulating preinflammatory factors in aging, young animals had higher numbers of monocytes and granulocytes in the follicles, a profile negatively associated with numbers of Tfh cells. Multiple regression analysis showed an altered association between GC B cells and other GC immune cell populations in old animals suggesting a differential mechanistic regulation of GC activity in aging. Our data demonstrate defective baseline GC composition in old NHPs and provide an immunological base for further understanding the adaptive humoral responses with respect to aging.

Brain macrophages harbor latent, infectious simian immunodeficiency virus

: The current review examines the role of brain macrophages, that is perivascular macrophages and microglia, as a potential viral reservoir in antiretroviral therapy (ART) treated, simian immunodeficiency virus (SIV)-infected macaques. The role, if any, of latent viral reservoirs of HIV and SIV in the central nervous system during ART suppression is an unresolved issue. HIV and SIV infect both CD4 lymphocytes and myeloid cells in blood and tissues during acute and chronic infection. HIV spread to the brain occurs during acute infection by the infiltration of activated CD4 lymphocytes and monocytes from blood and is established in both embryonically derived resident microglia and monocyte-derived perivascular macrophages. ART controls viral replication in peripheral blood and cerebrospinal fluid in HIV-infected individuals but does not directly eliminate infected cells in blood, tissues or brain. Latently infected resting CD4 lymphocytes in blood and lymphoid tissues are a well recognized viral reservoir that can rebound once ART is withdrawn. In contrast, central nervous system resident microglia and perivascular macrophages in brain have not been examined as potential reservoirs for HIV during suppressive ART. Macrophages in tissues are long-lived cells that are HIV and SIV infected in tissues such as gut, lung, spleen, lymph node and brain and contribute to ongoing inflammation in tissues. However, their potential role in viral persistence and latency or their potential to rebound in the absence ART has not been examined. It has been shown that measurement of HIV latency by HIV DNA PCR in CD4 lymphocytes overestimates the size of the latent reservoirs of HIV that contribute to rebound that is cells containing the genomes of replicative viruses. Thus, the quantitative viral outgrowth assay has been used as a reliable measure of the number of latent cells that harbor infectious viral DNA and, may constitute a functional latent reservoir. Using quantitative viral outgrowth assays specifically designed to quantitate latently infected CD4 lymphocytes and myeloid cells in an SIV macaque model, we demonstrated that macrophages in brain harbor SIV genomes that reactivate and produce infectious virus in this assay, demonstrating that these cells have the potential to be a reservoir.

Myeloid and CD4 T Cells Comprise the Latent Reservoir in Antiretroviral Therapy-Suppressed SIVmac251-Infected Macaques

Human immunodeficiency virus (HIV) eradication or long-term suppression in the absence of antiretroviral therapy (ART) requires an understanding of all viral reservoirs that could contribute to viral rebound after ART interruption. CD4 T cells (CD4s) are recognized as the predominant reservoir in HIV type 1 (HIV-1)-infected individuals. However, macrophages are also infected by HIV-1 and simian immunodeficiency virus (SIV) during acute infection and may persist throughout ART, contributing to the size of the latent reservoir. We sought to determine whether tissue macrophages contribute to the SIVmac251 reservoir in suppressed macaques. Using cell-specific quantitative viral outgrowth assays (CD4-QVOA and MΦ-QVOA), we measured functional latent reservoirs in CD4s and macrophages in ART-suppressed SIVmac251-infected macaques. Spleen, lung, and brain in all suppressed animals contained latently infected macrophages, undetectable or low-level SIV RNA, and detectable SIV DNA. Silent viral genomes with potential for reactivation and viral spread were also identified in blood monocytes, although these cells might not be considered reservoirs due to their short life span. Additionally, virus produced in the MΦ-QVOA was capable of infecting healthy activated CD4s. Our results strongly suggest that functional latent reservoirs in CD4s and macrophages can contribute to viral rebound and reestablishment of productive infection after ART interruption. These findings should be considered in the design and implementation of future HIV cure strategies.IMPORTANCE This study provides further evidence that the latent reservoir is comprised of both CD4+ T cells and myeloid cells. The data presented here suggest that CD4+ T cells and macrophages found throughout tissues in the body can contain replication-competent SIV and contribute to rebound of the virus after treatment interruption. Additionally, we have shown that monocytes in blood contain latent virus and, though not considered a reservoir themselves due to their short life span, could contribute to the size of the latent reservoir upon entering the tissue and differentiating into long-lived macrophages. These new insights into the size and location of the SIV reservoir using a model that is heavily studied in the HIV field could have great implications for HIV-infected individuals and should be taken into consideration with the development of future HIV cure strategies.

In vitro and in silico Models to Study Mosquito-Borne Flavivirus Neuropathogenesis, Prevention, and Treatment

Mosquito-borne flaviviruses can cause disease in the nervous system, resulting in a significant burden of morbidity and mortality. Disease models are necessary to understand neuropathogenesis and identify potential therapeutics and vaccines. Non-human primates have been used extensively but present major challenges. Advances have also been made toward the development of humanized mouse models, but these models still do not fully represent human pathophysiology. Recent developments in stem cell technology and cell culture techniques have allowed the development of more physiologically relevant human cell-based models. In silico modeling has also allowed researchers to identify and predict transmission patterns and discover potential vaccine and therapeutic candidates. This review summarizes the research on in vitro and in silico models used to study three mosquito-borne flaviviruses that cause neurological disease in humans: West Nile, Dengue, and Zika. We also propose a roadmap for 21st century research on mosquito-borne flavivirus neuropathogenesis, prevention, and treatment.

Passive infusion of Fc-modified neutralizing antibodies does not affect the dynamics of plasma virus decay in SHIV-infected macaques

Passive neutralizing antibody (NAb) infusion leads to a reduction of HIV plasma viremia in infected people as well as in SHIV-infected rhesus macaques. Potential mechanisms of viral reduction include neutralization of free virus as well as Fc-dependent effector functions that can clear infected cells. We generated several Fc variants of the human IgG1 NAb VRC07-523LS and characterized them for neutralization, complement binding, ADCC, phagocytosis, and binding to rhesus FcgR. Based on these assays, we down selected two variants, LALA and DEL, that showed knock-out or increase in ADCC and phagocytosis respectively, with complement binding knocked out in both. The parental, LALA and DEL variants of VRC07-523LS were administered at a single dose of 20 mg/kg i.v. to rhesus macaques chronically infected with SHIV-SF162P3 for 6–14 weeks (n=6 to 10 per group). Animals were followed for rate of plasma virus decay and antibody PK. All groups showed similar characteristics: 1) plasma virus decay was delayed for 24h after NAb infusion 2) the rate of plasma virus decay was the same between day 1 and day 5, and 3) plasma virus decay was independent of FcgRIII genotype. Pharmacokinetic analysis showed that serum NAb concentrations in the VRC07-523LS, LALA and DEL groups were maintained at greater than ten-fold excess of the in vitro IC80 against SHIV SF162P3 throughout the period of investigation. Further, unlike VRC07-523LS-LALA, VRC07-523LS-DEL was able to engage natural killer cells and monocytes and mediate both HIV envelope-dependent ADCC and phagocytosis. These results show that the initial impact on plasma viremia by passive NAb therapy is predominantly mediated by virus neutralization rather than ADCC or phagocytosis.

A Quantitative Approach to SIV Functional Latency in Brain Macrophages

Lentiviruses are retroviruses that primarily infect myeloid cells, leading to acute inflammatory infections in many tissues particularly, lung, joints and the central nervous system (CNS). Acute infection by lentiviruses is followed by persistent/latent infections that are not cleared by the host immune system. HIV and SIV are lentiviruses that also infect CD4+ lymphocytes as well as myeloid cells in blood and multiple tissues. HIV infection of myeloid cells in brain, lung and heart cause tissue specific diseases as well as infect cells in gut, lymph nodes and spleen. AIDS dementia and other tissue specific disease are observed when infected individuals are immunosuppressed and the number of circulating CD4+ T cells declines to low levels. Antiretroviral therapy (ART) controls viral spread and dramatically changes the course of immunodeficiency and AIDS dementia. However, ART does not eliminate virus-infected cells. Brain macrophages contain HIV DNA and may represent a latent reservoir that persists. HIV latency in CD4+ lymphocytes is the main focus of current research and concern in efforts to eradicate HIV. However, a number of studies have demonstrated that myeloid cells in blood and tissues of ART suppressed individuals harbor HIV DNA. The resident macrophages in tissues such as brain (microglia), spleen (red pulp macrophages) and alveolar macrophages in lung are derived from the yolk sac and can self renew. The question of the latent myeloid reservoir in HIV has not been rigorously examined and its potential as a barrier to eradication been considered. Using a well characterized SIV ART suppressed, non-human primate (NHP) model, our laboratory developed the first quantitative viral outgrowth assay (QVOA) designed to evaluate latently infected CD4+ lymphocytes and more recently developed a similar protocol for the assessment of latently infected myeloid cells in blood and brain. Using an SIV ART model, it was demonstrated that myeloid cells in blood and brain harbor latent SIV that can be reactivated and produce infectious virus in vitro. These studies demonstrate for the first time that myeloid cells have the potential to be a latent reservoir of HIV that produces infectious virus that can be reactivated in the absence of ART and during HIV eradication strategies. Graphical Abstract.

Microglia Increase Inflammatory Responses in iPSC-Derived Human BrainSpheres

Human induced pluripotent stem cells (iPSCs), together with 21st century cell culture methods, have the potential to better model human physiology with applications in toxicology, disease modeling, and the study of host-pathogen interactions. Several models of the human brain have been developed recently, demonstrating cell-cell interactions of multiple cell types with physiologically relevant 3D structures. Most current models, however, lack the ability to represent the inflammatory response in the brain because they do not include a microglial cell population. Microglia, the resident immunocompetent phagocytes in the central nervous system (CNS), are not only important in the inflammatory response and pathogenesis; they also function in normal brain development, strengthen neuronal connections through synaptic pruning, and are involved in oligodendrocyte and neuronal survival. Here, we have successfully introduced a population of human microglia into 3D human iPSC-derived brain spheres (BrainSpheres, BS) through co-culturing cells of the Immortalized Human Microglia – SV40 cell line with the BS model (μBS). We detected an inflammatory response to lipopolysaccharides (LPS) and flavivirus infection, which was only elicited in the model when microglial cells were present. A concentration of 20 ng/mL of LPS increased gene expression of the inflammatory cytokines interleukin-6 (IL-6), IL-10, and IL-1β, with maximum expression at 6–12 h post-exposure. Increased expression of the IL-6, IL-1β, tumor necrosis factor alpha (TNF-α), and chemokine (C-C motif) ligand 2 (CCL2) genes was observed in μBS following infection with Zika and Dengue Virus, suggesting a stronger inflammatory response in the model when microglia were present than when only astrocyte, oligodendrocyte, and neuronal populations were represented. Microglia innately develop within cerebral organoids (Nature communications)¹, our findings suggest that the μBS model is more physiologically relevant and has potential applications in infectious disease and host-pathogen interactions research.

Comprehensive Antiretroviral Restriction Factor Profiling Reveals the Evolutionary Imprint of the ex Vivo and in Vivo IFN-β Response in HTLV-1-Associated Neuroinflammation

HTLV-1-Associated Myelopathy (HAM/TSP) is a progressive neuroinflammatory disorder for which no disease-modifying treatment exists. Modest clinical benefit from type I interferons (IFN-α/β) in HAM/TSP contrasts with its recently identified IFN-inducible gene signature. In addition, IFN-α treatment in vivo decreases proviral load and immune activation in HAM/TSP, whereas IFN-β therapy decreases tax mRNA and lymphoproliferation. We hypothesize this "IFN paradox" in HAM/TSP might be explained by both cell type- and gene-specific effects of type I IFN in HTLV-1-associated pathogenesis. Therefore, we analyzed ex vivo transcriptomes of CD4⁺ T cells, PBMCs and whole blood in healthy controls, HTLV-1-infected individuals, and HAM/TSP patients. First, we used a targeted approach, simultaneously quantifying HTLV-1 mRNA (HBZ, Tax), proviral load and 42 host genes with known antiretroviral (anti-HIV) activity in purified CD4⁺ T cells. This revealed two major clusters ("antiviral/protective" vs. "proviral/deleterious"), as evidenced by significant negative (TRIM5/TRIM22/BST2) vs. positive correlation (ISG15/PAF1/CDKN1A) with HTLV-1 viral markers and clinical status. Surprisingly, we found a significant inversion of antiretroviral activity of host restriction factors, as evidenced by opposite correlation to in vivo HIV-1 vs. HTLV-1 RNA levels. The anti-HTLV-1 effect of antiviral cluster genes was significantly correlated to their adaptive chimp/human evolution score, for both Tax mRNA and PVL. Six genes of the proposed antiviral cluster underwent lentivirus-driven purifying selection during primate evolution (TRIM5/TRIM22/BST2/APOBEC3F-G-H), underscoring the cross-retroviral evolutionary imprint. Secondly, we examined the genome-wide type I IFN response in HAM/TSP patients, following short-term ex vivo culture of PBMCs with either IFN-α or IFN-β. Microarray analysis evidenced 12 antiretroviral genes (including TRIM5α/TRIM22/BST2) were significantly up-regulated by IFN-β, but not IFN-α, in HAM/TSP. This was paralleled by a significant decrease in lymphoproliferation by IFN-β, but not IFN-α treatment. Finally, using published ex vivo whole blood transcriptomic data of independent cohorts, we validated the significant positive correlation between TRIM5, TRIM22, and BST2 in HTLV-1-infected individuals and HAM/TSP patients, which was independent of the HAM/TSP disease signature. In conclusion, our results provide ex vivo mechanistic evidence for the observed immunovirological effect of in vivo IFN-β treatment in HAM/TSP, reconcile an apparent IFN paradox in HTLV-1 research and identify biomarkers/targets for a precision medicine approach.

SIV Latency in Macrophages in the CNS

Lentiviruses infect myeloid cells, leading to acute infection followed by persistent/latent infections not cleared by the host immune system. HIV and SIV are lentiviruses that infect CD4+ lymphocytes in addition to myeloid cells in blood and tissues. HIV infection of myeloid cells in brain, lung, and heart causes tissue-specific diseases that are mostly observed during severe immunosuppression, when the number of circulating CD4+ T cells declines to exceeding low levels. Antiretroviral therapy (ART) controls viral replication but does not successfully eliminate latent virus, which leads to viral rebound once ART is interrupted. HIV latency in CD4+ lymphocytes is the main focus of research and concern when HIV eradication efforts are considered. However, myeloid cells in tissues are long-lived and have not been routinely examined as a potential reservoir. Based on a quantitative viral outgrowth assay (QVOA) designed to evaluate latently infected CD4+ lymphocytes, a similar protocol was developed for the assessment of latently infected myeloid cells in blood and tissues. Using an SIV ART model, it was demonstrated that myeloid cells in blood and brain harbor latent SIV that can be reactivated and produce infectious virus in vitro, demonstrating that myeloid cells have the potential to be an additional latent reservoir of HIV that should be considered during HIV eradication strategies.

Lymphocyte-Dominant Encephalitis and Meningitis in Simian Immunodeficiency Virus-Infected Macaques Receiving Antiretroviral Therapy

A retrospective neuropathologic review of 30 SIV-infected pigtailed macaques receiving combination antiretroviral therapy (cART) was conducted. Seventeen animals with lymphocyte-dominant inflammation in the brain and/or meninges that clearly was morphologically distinct from prototypic SIV encephalitis and human immunodeficiency virus encephalitis were identified. Central nervous system (CNS) infiltrates in cART-treated macaques primarily comprised CD20⁺ B cells and CD3⁺ T cells with fewer CD68⁺ macrophages. Inflammation was associated with low levels of SIV RNA in the brain as shown by in situ hybridization, and generally was observed in animals with episodes of cerebrospinal fluid (CSF) viral rebound or sustained plasma and CSF viremia during treatment. Although the lymphocytic CNS inflammation in these macaques shared morphologic characteristics with uncommon immune-mediated neurologic disorders reported in treated HIV patients, including CNS immune reconstitution inflammatory syndrome and neurosymptomatic CSF escape, the high prevalence of CNS lesions in macaques suggests that persistent adaptive immune responses in the CNS also may develop in neuroasymptomatic or mildly impaired HIV patients yet remain unrecognized given the lack of access to CNS tissue for histopathologic evaluation. Continued investigation into the mechanisms and outcomes of CNS inflammation in cART-treated, SIV-infected macaques will advance our understanding of the consequences of residual CNS HIV replication in patients on cART, including the possible contribution of adaptive immune responses to HIV-associated neurocognitive disorders.

New-Generation High-Potency and Designer Antibodies: Role in HIV-1 Treatment

Broadly neutralizing antibodies (bNAbs) have been evaluated as promising agents in the fight against infectious diseases. HIV-1-specific bNAbs, in particular, have been tested in both preventive and therapeutic modalities. Multiple bNAbs have been isolated, characterized, and assessed in vitro and in vivo, but no single antibody appears to possess the breadth and potency that may be needed if it is to be used in the treatment of HIV-1 infection. With the technological advances of the past decades, novel and more effective bNAbs have been identified or engineered for higher neutralizing potency, greater breadth, and increased serum half-life. In this review, we discuss the development of a new generation of anti-HIV-1 bNAbs and their potential to be used clinically for treatment and prevention of HIV-1 infection.

An SIV/macaque model targeted to study HIV-associated neurocognitive disorders

Simian immunodeficiency virus (SIV) infection of pigtailed macaques is a highly representative and well-characterized animal model for HIV neuropathogenesis studies that provides an excellent opportunity to study and develop prognostic markers of HIV-associated neurocognitive disorders (HAND) for HIV-infected individuals. SIV studies can be performed in a controlled setting that enhances reproducibility and offers high-translational value. Similar to observations in HIV-infected patients receiving antiretroviral therapy (ART), ongoing neurodegeneration and inflammation are present in SIV-infected pigtailed macaques treated with suppressive ART. By developing quantitative viral outgrowth assays that measure both CD4+ T cells and macrophages harboring replication competent SIV as well as a highly sensitive mouse-based viral outgrowth assay, we have positioned the SIV/pigtailed macaque model to advance our understanding of latent cellular reservoirs, including potential CNS reservoirs, to promote HIV cure. In addition to contributing to our understanding of the pathogenesis of HAND, the SIV/pigtailed macaque model also provides an excellent opportunity to test innovative approaches to eliminate the latent HIV reservoir in the brain.

Unique intrahepatic transcriptomics profiles discriminate the clinical phases of a chronic HBV infection

Chronic hepatitis B is a highly heterogeneous liver disease characterized by phases with fluctuations in viral replication and progressive liver damage in some, but not all infected individuals. Despite four decades of research, insight into host determinants underlying these distinct clinical phases-immunotolerant, immune active, inactive carrier, and HBeAg-negative hepatitis-remains elusive. We performed an in-depth transcriptome analysis of archived FFPE liver biopsies of each clinical phase to address host determinants associated with the natural history. Therefore, we determined, for the first time, intrahepatic global expression profiles of well-characterized chronic HBV patients at different clinical phases. Our data, obtained by microarray, demonstrate that B cells and NK/cytotoxic-related genes in the liver, including CD19, TNFRSF13C, GZMH, and KIR2DS3, were differentially expressed across the clinical HBV phases, which was confirmed by modular analysis and also Nanostring arrays in an independent cohort. Compared to the immunotolerant phase, 92 genes were differentially expressed in the liver during the immune active phase, 46 in the inactive carrier phase, and 71 in the HBeAg-negative phase. Furthermore, our study also revealed distinctive transcription of genes associated with cell cycle activity, NF-κB signaling, cytotoxic function and mitochondrial respiration between clinical phases. Our data define for the first time using microarray unique transcriptomes in the HBV-infected liver during consecutive clinical phases. We demonstrate that fluctuations of viral loads and liver damage coincide with fluctuations in the liver transcriptome and point to functional- immune and non-immune- components contributing to the clinical phenotype in patients.

The effect of Ingenol-B on the suppressive capacity of elite suppressor HIV-specific CD8+ T cells

Background

Some latency-reversing agents (LRAs) inhibit HIV-specific CD8+ T cell responses. In a prior study of protein kinase C (PKC) agonists, we found that bryostatin-1 inhibited elite controller/suppressor (ES) CD8+ T cell suppressive activity whereas prostratin had no effect. Ingenol-B is another PKC agonist with potent LRA activity both by itself and in combination with the bromodomain inhibitor JQ1; however its effect on CD8+ T cell mediated control of HIV-1 replication is unknown.

Methods

CD8+ T cells were isolated from ES and treated with bryostatin-1, prostratin, ingenol-B, and JQ1 as well as a combination of each PKC-agonist with JQ1. The cells were then tested in the viral suppression assay. To assess possible mechanisms of inhibition, CD8+ T cells were treated with the LRAs and analyzed for the expression of various immune cell markers.

Results

Ingenol-B had no effect on the ability of ES CD8+ T cells to suppress viral replication, however, the combination of ingenol-B and JQ1 caused a modest, but significant decrease in this suppressive capacity. The mechanism of the inhibitory effect of the JQ1 and ingenol-B combination relative to ingenol-B alone was unclear but the effect appeared to be dose dependent.

Conclusions

Ingenol-B does not inhibit HIV-specific CD8+ T cell responses in vitro. These responses are however modestly inhibited when 100 nMingenol-B is combined with JQ1. Since HIV-specific CD8+ T cell activity may be essential for the eradication of reactivated latently infected cells, the potency of latency-reversal activity of drug combinations must be balanced against the effects of the combinations on HIV-specific CD8+ T cell responses.

Effects of the PKC agonist Ingenol-B on HIV suppression by CD8+ T cells

Shock and kill strategies have been proposed as a possible mechanism for HIV-1 eradication. These strategies involve the use of latency-reversing agents (LRAs) such as PKC-agonists, to “shock” latently infected CD4+ T cells and myeloid cells into producing viral proteins that could then be recognized by effector cells leading to the “kill” component of the strategy. In its wake, recent studies have shown that some LRAs inhibit HIV-specific CD8+ T cell responses, suggesting that LRAs should be screened for immunosuppressive properties before use in clinical trials. In a prior study to determine whether PKC agonists could inhibit the potent HIV-specific CD8+ T cell responses seen in patients who control HIV replication naturally (elite suppressors, ES), we found that Bryostatin-1, but not Prostratin, inhibited ES CD8+ T cell responses. Ingenol-B is another PKC agonist with potent LRA activity both by itself and in combination with the bromodomain inhibitor JQ1. In this study, we determined the effect of this drug on CD8+ T cells from 6 ES.

We show here that while Ingenol-B had no effect on the ability of CD8+ T cells to suppress viral replication (65.3% suppression versus 59.3% with DMSO, p &gt; 0.05), its combination with JQ1 caused a modest, but significant, decrease in this suppressive capacity (39.9%, p= 0.033). The mechanism of this inhibitory effect could not be readily explained by differences in PD-1, TIM-3 or CD3 expression on CD8+ T cells. We conclude that since robust CD8+ T cell activity is essential for the eradication of reactivated latently infected cells, the potency of LRA combinations must be balanced against their effect on HIV-specific CD8+ T cell responses.

Toll-like receptor 2bright cells identify circulating monocytes in human and non-human primates

Polychromatic flow cytometry is a useful tool for monitoring circulating whole blood monocytes, although gating strategies often vary depending on the study. Increased analyses of the myeloid system have revealed monocytes to be more plastic than previously understood and uncovered changes among surface markers previously considered to be stable. The myeloid system has also been found to have disparate surface markers between mouse, human, and non‐human primate studies, which further complicates examination between species. This study has found bright Toll‐like receptor 2 (TLR2) expression to be a consistent surface marker of circulating whole blood monocytes in humans and two species of macaques. Furthermore, within our pigtailed macaque model of HIV‐associated CNS disease, where monocyte surface markers have previously been shown to reorganize during acute infection, TLR2 remains stably expressed on the surface of classical, intermediate, and non‐classical monocytes. Our findings demonstrate that TLR2 is a useful surface marker for including all monocytes during other phenotypic changes that may alter the expression of common surface receptors. These results provide a practical tool for studying all types of monocytes during inflammation and infection within humans and macaques. © 2017 The Authors. Cytometry Part A Published by Wiley Periodicals, Inc. on behalf of ISAC.

Liver Monocytes and Kupffer Cells Remain Transcriptionally Distinct during Chronic Viral Infection

Due to the scarcity of immunocompetent animal models for chronic viral hepatitis, little is known about the role of the innate intrahepatic immune system during viral replication in the liver. These insights are however fundamental for the understanding of the inappropriate adaptive immune responses during the chronic phase of the infection. We apply the Lymphocytic Choriomenigitis Virus (LCMV) clone 13 mouse model to examine chronic virus-host interactions of Kupffer cells (KC) and infiltrating monocytes (IM) in an infected liver. LCMV infection induced overt clinical hepatitis, with rise in ALT and serum cytokines, and increased intrahepatic F4/80 expression. Despite ongoing viral replication, whole liver transcriptome showed baseline expression levels of inflammatory cytokines, interferons, and interferon induced genes during the chronic infection phase. Transcriptome analyses of sorted KC and IMs using NanoString technology revealed two unique phenotypes with only minimal overlap. At the chronic viral infection phase, KC showed no increased transcription of activation markers Cd80 and Cd86, but an increased expression of genes related to antigen presentation, whereas monocytes were more activated and expressed higher levels of Tnf transcripts. Although both KCs and intrahepatic IM share the surface markers F4/80 and CD11b, their transcriptomes point towards distinctive roles during virus-induced chronic hepatitis.

HIV Suppression Restores the Lung Mucosal CD4+ T-Cell Viral Immune Response and Resolves CD8+ T-Cell Alveolitis in Patients at Risk for HIV-Associated Chronic Obstructive Pulmonary Disease

BACKGROUND

Lung CD4⁺ T-cell depletion and dysfunction, CD8⁺ T-cell alveolitis, smoking, and poor control of human immunodeficiency virus (HIV) are features of HIV-associated chronic obstructive pulmonary disease (COPD), but these changes have not been evaluated in smokers at risk for COPD. We evaluated the impact of viral suppression following initiation of antiretroviral therapy (ART) on HIV-specific immunity and the balance of the CD4⁺ T-cell to CD8⁺ T-cell ratio in the lung.

METHODS

Using flow cytometry, we assessed the T-cell immune response in lung and blood specimens obtained from 12 actively smoking HIV-positive patients before ART initiation and after ART-associated viral suppression.

RESULTS

HIV suppression resulted in enhanced lung and systemic HIV-specific CD4⁺ T-cell immune responses without significant changes in CD8⁺ T-cell responses. We observed an increase in lung ratios of CD4⁺ T cells to CD8⁺ T cells and CD4⁺ T-cell frequencies, decreased CD8⁺ T-cell numbers, and resolution of CD8⁺ T-cell alveolitis after ART in 9 of 12 individuals. Viral suppression reduced Fas receptor and programmed death 1 expression in lung CD4⁺ T cells, correlating with enhanced effector function and reduced susceptibility to apoptosis. HIV suppression rescued peripheral but not lung HIV-specific CD4⁺ T-cell proliferation, resulting in augmented effector multifunction.

DISCUSSION

Together, our results demonstrate that HIV suppression restores lung mucosal HIV-specific CD4⁺ T-cell multifunctional immunity and balance in the ratio of CD4⁺ T cells to CD8⁺ T cells, often resolving CD8⁺ T-cell alveolitis in active smokers. Peripheral expansion and redistribution of CD4⁺ T cells and increased resistance to apoptosis are 2 mechanisms contributing to immunologic improvement following viral suppression in patients at risk for HIV-associated COPD.

Splenic Damage during SIV Infection: Role of T-Cell Depletion and Macrophage Polarization and Infection

The effects of HIV infection on spleen and its cellular subsets have not been fully characterized, particularly for macrophages in which diverse populations exist. We used an accelerated SIV-infected macaque model to examine longitudinal effects on T-cell and macrophage populations and their susceptibilities to infection. Substantial lymphoid depletion occurred, characterized by follicular burn out and a loss of CD3 T lymphocytes, which was associated with cellular activation and transient dysregulations in CD4/CD8 ratios and memory effector populations. In contrast, the loss of CD68 and CD163(+)CD68(+) macrophages and increase in CD163 cells was irreversible, which began during acute infection and persisted until terminal disease. Mac387 macrophages and monocytes were transiently recruited into spleen, but were not sufficient to mitigate the changes in macrophage subsets. Type I interferon, M2 polarizing genes, and chemokine-chemokine receptor signaling were up-regulated in spleen and drove macrophage alterations. SIV-infected T cells were numerous within the white pulp during acute infection, but were rarely observed thereafter. CD68, CD163, and Mac387 macrophages were highly infected, which primarily occurred in the red pulp independent of T cells. Few macrophages underwent apoptosis, indicating that they are a long-lasting target for HIV/SIV. Our results identify macrophages as an important contributor to HIV/SIV infection in spleen and in promoting morphologic changes through the loss of specific macrophage subsets that mediate splenic organization.

Abstract 563: Activated Circulating Intermediate Monocytes are Associated with Subclinical Coronary Plaque in Apparently Healthy Middle-Aged Men

Background: The intermediate subset accounts for the smallest percentage of circulating monocytes yet has been associated with chronic inflammatory diseases, including CAD outcomes. It is unknown if activated intermediate monocytes (IM) are associated with coronary plaque at an earlier stage in atherosclerosis, prior to clinical manifestations.

Methods: We screened 11 healthy nondiabetic, non statin using, age-matched males for the presence and extent of coronary plaque using advanced dual-source CT angiography. Total coronary plaque (TCP) volumes (mm3) were quantified using a validated automated method and transformed to log(TCP+1). To examine monocyte subsets, whole blood was labeled to exclude non-monocytic cells. Surface CD14, CD16, TLR2, CX3CR1, and CD11b were used to confirm monocyte subsets by flow cytometry with HLA-DRhi as a marker of activation.

Results: Mean age was 54±2 (range 49 to 57); 36% were African American, 27% were smokers, and 45% had hypertension. Mean LDL-C was 121±38. The absolute number of circulating activated IM per cu mm was higher in the 6 individuals with coronary plaque compared to the 5 with no plaque (42.6±24.8 vs. 15.6±11.9, p=0.05). In bivariate analysis the number of activated IM was significantly associated with TCP (Figure, r=0.71, p=0.01). These associations were not found with classical and nonclassical monocytes.

Conclusion: In a small population of age-matched, nondiabetic apparently healthy middle-aged men not on statin therapy, the number of circulating activated IM was associated with the presence and volume of subclinical coronary plaque. Further investigation of monocyte activation prior to plaque development is ongoing.

A Murine Viral Outgrowth Assay to Detect Residual HIV Type 1 in Patients With Undetectable Viral Loads

BACKGROUND

Sensitive assays are needed for detection of residual human immunodeficiency virus (HIV) in patients with undetectable plasma viral loads to determine whether eradication strategies are effective. The gold standard quantitative viral outgrowth assay (QVOA) underestimates the magnitude of the viral reservoir. We sought to determine whether xenograft of leukocytes from HIV type 1 (HIV)-infected patients with undetectable plasma viral loads into immunocompromised mice would result in viral amplification.

METHODS

Peripheral blood mononuclear cells or purified CD4(+) T cells from HIV or simian immunodeficiency virus (SIV)-infected subjects with undetectable plasma viral loads were adoptively transferred into NOD.Cg-Prkdc(scid)Il2rg(tm1Wjl)/SzJ (NSG) mice. The mice were monitored for viremia following depletion of human CD8(+) T cells to minimize antiviral activity. In some cases, humanized mice were also treated with activating anti-CD3 antibody.

RESULTS

With this murine viral outgrowth assay (MVOA), we successfully amplified replication-competent HIV or SIV from all subjects tested, including 5 HIV-positive patients receiving suppressive antiretroviral therapy (ART) and 6 elite controllers or suppressors who were maintaining undetectable viral loads without ART, including an elite suppressor from whom we were unable to recover virus by QVOA.

CONCLUSIONS

Our results suggest that the MVOA has the potential to serve as a powerful tool to identify residual HIV in patients with undetectable viral loads.

Paving the path to HIV neurotherapy: Predicting SIV CNS disease

HIV-induced damage to the CNS remains a major challenge for over 30 million people in the world despite the successes of combined antiretroviral therapy in limiting viral replication. Predicting development and progression of HIV-associated CNS disease is crucial because prevention and early intervention could be more effective than attempts to promote repair. The SIV/macaque model is the premier platform to study HIV neuropathogenesis, including discovery of predictive factors such as neuroprotective host genes and both blood and CSF biomarkers that precede and predict development of SIV CNS disease. This report details the role of macaque MHC class I genes, longitudinal alterations in biomarkers in the circulation, and expression of inflammatory and neuronal damage markers in CSF using samples from SIV-inoculated pigtailed macaques collected during acute, asymptomatic, and terminal stages of infection.

Activation-induced cell death drives profound lung CD4(+) T-cell depletion in HIV-associated chronic obstructive pulmonary disease

RATIONALE

As overall survival improves, individuals with HIV infection become susceptible to other chronic diseases, including accelerated chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To determine whether individuals with HIV-associated COPD exhibit dysregulated lung mucosal T-cell immunity compared with control subjects.

METHODS

Using flow cytometry, we evaluated peripheral blood and lung mucosal T-cell immunity in 14 HIV(+)COPD(+), 13 HIV(+)COPD(-), and 7 HIV(-)COPD(+) individuals.

MEASUREMENTS AND MAIN RESULTS

HIV(+)COPD(+) individuals demonstrated profound CD4(+) T-cell depletion with reduced CD4/CD8 T-cell ratios in bronchoalveolar lavage-derived lung mononuclear cells, not observed in peripheral blood mononuclear cells, and diminished CD4(+) T cell absolute numbers, compared with control subjects. Furthermore, HIV(+)COPD(+) individuals demonstrated decreased pulmonary HIV-specific and staphylococcal enterotoxin B-reactive CD4(+) memory responses, including loss of multifunctionality, compared with HIV(+)COPD(-) control subjects. In contrast, lung mucosal HIV-specific CD8(+) T-cell responses were preserved. Lung CD4(+) T cells from HIV(+)COPD(+) individuals expressed increased surface Fas death receptor (CD95) and programmed death-1, but similar bronchoalveolar lavage viral loads as control subjects. However, programmed death-1 expression inversely correlated with HIV-specific lung CD4(+)IFN-γ(+) T-cell responses, suggesting functional exhaustion. Moreover, lung CD4(+) T cells from HIV(+)COPD(+) patients demonstrated increased basal and HIV antigen-induced expression of the early apoptosis marker annexin V compared with control subjects, which was significantly attenuated with anti-Fas blockade. Lastly, lung mucosal, but not blood, CD4(+)/CD8(+) ratios from HIV(+) patients significantly correlated with the FEV1, but not in HIV(-)COPD(+) patients.

CONCLUSIONS

Together, our results provide evidence for profound lung mucosal CD4(+) T-cell depletion via a Fas-dependent activation-induced cell death mechanism, along with impaired HIV-specific CD4(+) immunity as immunologic features of HIV-associated COPD.

Elevated brain monoamine oxidase activity in SIV- and HIV-associated neurological disease

We recently demonstrated direct evidence of increased monoamine oxidase (MAO) activity in the brain of a simian immunodeficiency virus (SIV) model of human immunodeficiency virus (HIV)-associated central nervous system (CNS) disease, consistent with previously reported dopamine deficits in both SIV and HIV infection. In this study, we explored potential mechanisms behind this elevated activity. MAO B messenger RNA was highest in macaques with the most severe SIV-associated CNS lesions and was positively correlated with levels of CD68 and GFAP transcripts in the striatum. MAO B messenger RNA also correlated with viral loads in the CNS of SIV-infected macaques and with oxidative stress. Furthermore, in humans, striatal MAO activity was elevated in individuals with HIV encephalitis, compared with activity in HIV-seronegative controls. These data suggest that the neuroinflammation and oxidative stress caused by SIV infection in the CNS may provide the impetus for increased transcription of MAO B and that MAO, and more broadly, oxidative stress, have significant potential as therapeutic targets in CNS disease due to HIV.