Effect of HIV Antibody VRC01 on Viral Rebound after Treatment Interruption.

BACKGROUND: The discovery of potent and broadly neutralizing antibodies (bNAbs) against human immunodeficiency virus (HIV) has made passive immunization a potential strategy for the prevention and treatment of HIV infection. We sought to determine whether passive administration of VRC01, a bNAb targeting the HIV CD4-binding site, can safely prevent or delay plasma viral rebound after the discontinuation of antiretroviral therapy (ART). METHODS: We conducted two open-label trials (AIDS Clinical Trials Group [ACTG] A5340 and National Institutes of Health [NIH] 15-I-0140) of the safety, side-effect profile, pharmacokinetic properties, and antiviral activity of VRC01 in persons with HIV infection who were undergoing interruption of ART. RESULTS: A total of 24 participants were enrolled, and one serious alcohol-related adverse event occurred. Viral rebound occurred despite plasma VRC01 concentrations greater than 50 µg per milliliter. The median time to rebound was 4 weeks in the A5340 trial and 5.6 weeks in the NIH trial. Study participants were more likely than historical controls to have viral suppression at week 4 (38% vs. 13%, P=0.04 by a two-sided Fisher's exact test in the A5340 trial; and 80% vs. 13%, P<0.001 by a two-sided Fisher's exact test in the NIH trial) but the difference was not significant at week 8. Analyses of virus populations before ART as well as before and after ART interruption showed that VRC01 exerted pressure on rebounding virus, resulting in restriction of recrudescent viruses and selection for preexisting and emerging antibody neutralization-resistant virus. CONCLUSIONS: VRC01 slightly delayed plasma viral rebound in the trial participants, as compared with historical controls, but it did not maintain viral suppression by week 8. In the small number of participants enrolled in these trials, no safety concerns were identified with passive immunization with a single bNAb (VRC01). (Funded by the National Institute of Allergy and Infectious Diseases and others; ACTG A5340 and NIH 15-I-0140 ClinicalTrials.gov numbers, NCT02463227 and NCT02471326 .).

The glucocorticoid antagonist RU-486 suppresses HIV infectivity and replication.

The effects of RU-486, a glucocorticoid antagonist, on HIV infection and replication in depressed and nondepressed women were studied using ex vivo models of HIV infection. RU-486 treatment of cells decreased HIV reverse transcriptase activity of monocyte-derived macrophages in a model of acute infectivity. RU-486 also decreased HIV viral replication in the chronically-infected T-cell line ACH-2, but not in the promonocyte cell line U1. No differences were associated with depression status. Thus, glucocorticoid antagonism may suppress HIV infectivity and replication ex vivo. Studies to determine the role of glucocorticoid antagonists in the host defense against HIV should be performed.

Selective serotonin reuptake inhibitor suppression of HIV infectivity and replication.

OBJECTIVE: To test the hypothesis that the selective serotonin reuptake inhibitor (SSRI) citalopram would down-regulate human immunodeficiency virus (HIV) infectivity and that the greatest effects would be seen in people with depression. Depression is a risk factor for morbidity and mortality in HIV/acquired immune deficiency syndrome. Serotonin (5-HT) neurotransmission has been implicated in the pathobiology of depression, and pharmacologic therapies for depression target this system. The 5-HT transporter and 5-HT receptors are widely distributed throughout the central nervous and immune systems. Depression has been associated with suppression of natural killer cells and CD8(+) lymphocytes, key regulators of HIV infection. METHODS: Ex vivo models for acute and chronic HIV infection were used to study the effects of citalopram on HIV viral infection and replication in 48 depressed and nondepressed women. For both the acute and chronic infection models, HIV reverse transcriptase activity was measured in the citalopram treatment condition and the control condition. RESULTS: The SSRI significantly down-regulated the reverse transcriptase response in both the acute and chronic infection models. Specifically, citalopram significantly decreased the acute HIV infectivity of macrophages. Citalopram also significantly decreased HIV viral replication in the latently infected T-cell line and in the latently infected macrophage cell line. There was no difference in down-regulation by depression status. CONCLUSIONS: These studies suggest that an SSRI enhances natural killer/CD8 noncytolytic HIV suppression in HIV/acquired immune deficiency syndrome and decreases HIV viral infectivity of macrophages, ex vivo, suggesting the need for in vivo studies to determine a potential role for agents targeting serotonin in the host defense against HIV.

Validation of rapid HIV antibody tests in 5 African countries.

The sensitivity and specificity of 3 rapid HIV antibody tests were assessed at 5 clinical trial sites in Africa and 1 site in the United States using a minimum of 100 HIV antibody positive samples and 100 HIV antibody negative samples at each site. The overall sensitivity and specificity for the OraSure OraQuick, Abbott Determine, and Trinity Unigold tests were 99.3%, 99.8%, and 98.5%, respectively, and 99.3%, 99.4%, and 99.5%, respectively. There were no instances at any site in which false-negative or false-positive results were obtained for the same sample on more than 1 rapid test kit. The results of this study provide assurance that for these diverse sites in Africa, the accuracy of these kits is quite good. Given the excellent accuracy, relatively fast turnaround time, and minimal infrastructure required, these rapid tests for HIV antibody provide a very attractive and accurate testing format.

Decreased PD-1 Expression on CD8 Lymphocyte Subsets and Increase in CD8 Tscm Cells in Children with HIV Receiving Raltegravir.

We investigated the effect of combination antiretroviral therapy (cART) on immune recovery, particularly on the percentages of PD-1-positive cells within the major leukocyte subsets. Cryopreserved peripheral blood mononuclear cells and plasma samples collected longitudinally from a subset of 13 children and adolescents (between 9.7 and 18.2 years old) who were enrolled in the International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) P1066 were used for this study. Immunophenotyping by flow cytometry was performed to determine the effect of raltegravir-containing cART regimen on the distribution of leukocyte populations, on the expression of PD-1 on T cell subpopulations, and on the expression of well-established markers of T cell activation (CD38 and HLA-DR) on CD8 T cells. C reactive protein (CRP), lipopolysaccharide (LPS), IL-6, and soluble CD163 were assayed in plasma samples by an enzyme-linked immunosorbent assay. Plasma viral loads were decreased in all subjects (by an average of 2.9 log units). The cART regimen, including raltegravir, induced changes in CD8 T cell subsets, consistent with an effective antiretroviral outcome and improved immunologic status, including increased percentages of CD8 stem cell memory T cells (Tscm). The percentages of CD8 PD-1-positive cells decreased significantly as compared with baseline levels. Among the proinflammatory markers measured in plasma, sCD163 showed a decline that was associated with cART. cART therapy, including raltegravir, over 48 weeks in children is associated with immune restoration, consistent with effective antiretroviral therapy, namely decreased percentages of PD-1+ CD8+ T cells, an increase in CD8 Tscm cells, and decreased levels of sCD163.

Programmed death 1 receptor changes ex vivo in HIV-infected adults following initiation of highly active antiretroviral therapy.

This study investigates the short-term effects of highly active antiretroviral therapy (HAART) on programmed death 1 receptor (PD-1) expression and lymphocyte function. We compared lymphocytes from human immunodeficiency virus (HIV)-infected adults prior to the initiation of HAART with lymphocytes from the same subjects following 2 months of treatment. Short-term HAART resulted in a moderate increase in the expression of PD-1 on both CD4(+) and CD8(+) T cells; yet, there was still a significant reduction in viral load and recovery of CD4(+) T cells. After 2 months of HAART, lymphocytes from the subjects had a reduction in lymphoproliferative responses to phytohemagglutinin (PHA) and an increased response to the Candida recall antigen and the HIV antigen p24 compared to pretreatment lymphocytes. PHA-stimulated peripheral blood mononuclear cells (PBMCs) from samples obtained 2 months after HAART produced higher levels of Th-1 cytokines (gamma interferon [IFN-γ] and tumor necrosis factor alpha[TNF-α]) than the levels observed for samples taken before treatment was initiated. There were no significant changes in the proinflammatory cytokine interleukin-2 (IL-2) or Th-2 cytokines (IL-4, IL-5, and IL-10) in the corresponding samples. Ex vivo PD-1 blockade significantly augmented PHA-induced lymphoproliferation as well as the levels of Th-1 cytokines and to a lesser extent the levels of Th-2 cytokines in PBMC cultures. The ability to downregulate PD-1 expression may be important in enhancing immune recovery in HIV infection.

Optimization of storage and shipment of cryopreserved peripheral blood mononuclear cells from HIV-infected and uninfected individuals for ELISPOT assays.

Functional immunologic assays using cryopreserved peripheral blood mononuclear cells (PBMC) are influenced by blood processing, storage and shipment. The objective of this study was to compare the viability, recovery and ELISPOT results of PBMC stored and shipped in liquid nitrogen (LN/LN) or stored in LN and shipped on dry ice (LN/DI) or stored at -70°C for 3 to 12 weeks and shipped on DI (70/DI 3 to 12); and to assess the effect of donor HIV infection status on the interaction between storage/shipment and the outcome measures. PBMC from 12 HIV-infected and 12 uninfected donors showed that LN/LN conferred higher viability and recovery than LN/DI or 70/DI 3, 6, 9 or 12. LN/DI PBMC had higher viability than any 70/DI PBMC. The PBMC viability and recovery linearly decreased with the duration of storage at -70°C from 3 to 12 weeks. This effect was more pronounced in samples from HIV-infected than uninfected donors. Results of ELISPOT assays using CMV pp65, CEF and Candida albicans antigens were qualitatively and quantitatively similar across LN/LN, LN/DI and 70/DI 3. However, ELISPOT values significantly decreased with the duration of storage at -70°C both in HIV-infected and uninfected donors. ELISPOT results also decreased with PBMC viability <70%.

Novel method for determination of substance P levels in unextracted human plasma by using acidification.

Substance P (SP) is a member of the tachykinin family and has an important role in immune responses. SP is detectable in plasma in a free and bound state. Simple modification of a commercially available SP enzyme-linked immunosorbent assay allows the dissociation and capture of plasma SP without solid-phase extraction.

Selective serotonin reuptake inhibitor and substance P antagonist enhancement of natural killer cell innate immunity in human immunodeficiency virus/acquired immunodeficiency syndrome.

BACKGROUND: Natural killer (NK) cells play an important role in innate immunity and are involved in the host defense against human immunodeficiency virus (HIV) infection. This study examines the potential role of three underlying regulatory systems that have been under investigation in central nervous system research as well as immune and viral research: serotonin, neurokinin, and glucocorticoid systems. METHODS: Fifty-one HIV-seropositive subjects were recruited to achieve a representative sample of depressed and nondepressed women. The effects of a selective serotonin reuptake inhibitor (SSRI), a substance P (SP) antagonist, and a glucocorticoid antagonist on NK cell function were assessed in a series of ex vivo experiments of peripheral blood mononuclear cells from each HIV-seropositive subject. RESULTS: Natural killer cell cytolytic activity was significantly increased by the SSRI citalopram and by the substance P antagonist CP-96345 relative to control conditions; the glucocorticoid antagonist, RU486, showed no effect on NK cytotoxicity. Our results suggest that the effects of the three agents did not differ as a function of depression. CONCLUSIONS: Our findings provide evidence that NK cell function in HIV infection may be enhanced by serotonin reuptake inhibition and by substance P antagonism. It remains to be determined if HIV-related impairment in not only NK cytolytic activity but also NK noncytolytic activity can be improved by an SSRI or an SP antagonist. Clinical studies are warranted to address these questions and the potential roles of serotonergic agents and SP antagonists in improving NK cell immunity, delaying HIV disease progression, and extending survival with HIV infection.

Measurement of plasma-derived substance P: biological, methodological, and statistical considerations.

The undecapeptide substance P (SP) is a member of the tachykinin family of neurotransmitters, which has a pivotal role in the regulation of inflammatory and immune responses. One of the major barriers to the study of the in vivo role of SP in a number of immune disorders is the accurate measurement of SP in fluids. This is reflected in the variability of reported SP levels in serum and plasma of humans in both healthy and diseased states. This study was initiated in order to identify sources of variability by the comparative evaluation of the influences of sample preparation and analytical detection methods on the measurement of SP in plasma. The results indicate that sample preparation (peptide extraction versus no extraction) and the choice of analytical method for SP quantitation may yield significantly different values and may contribute to the variability in SP values reported in the literature. These results further emphasize the need for careful consideration in the selection of methods for SP quantitation, as well as caution in the interpretation and comparison of data reported in the literature.