Biology subjects

Balgeman, A. J.

Publications and source records attributed to Balgeman, A. J..

11 recordsLinked to original sources

bioRxiv2024

Transiently boosting Vγ9+Vδ2+ γδ T cells early in Mtb coinfection of SIV-infected juvenile macaques does not improve Mtb host resistance.

Children living with HIV have a higher risk of developing tuberculosis (TB), a disease caused by the bacterium Mycobacterium tuberculosis (Mtb). Gamma delta ({gamma}{delta}) T cells in the context of HIV/Mtb coinfection have been understudied in children, despite in vitro evidence suggesting {gamma}{delta} T cells assist with Mtb control. We investigated whether boosting a specific subset of {gamma}{delta} T cells, phosphoantigen-reactive V{gamma}9+V{delta}2+ cells, could improve TB outcome using a nonhuman primate model of pediatric HIV/Mtb coinfection. Juvenile Mauritian cynomolgus macaques (MCM), equivalent to 4-8-year-old children, were infected intravenously (i.v.) with SIV. After 6 months, MCM were coinfected with a low dose of Mtb and then randomized to receive zoledronate (ZOL), a drug that increases phosphoantigen levels, (n=5; i.v.) at 3- and 17-days after Mtb accompanied by recombinant human IL-2 (s.c.) for 5 days following each ZOL injection. A similarly coinfected MCM group (n=5) was injected with saline as a control. V{gamma}9+V{delta}2+ {gamma}{delta} T cell frequencies spiked in the blood, but not airways, of ZOL+IL-2-treated MCM following the first dose, however, were refractory to the second dose. At necropsy eight weeks after Mtb, ZOL+IL-2 treatment did not reduce pathology or bacterial burden. {gamma}{delta} T cell subset frequencies in granulomas did not differ between treatment groups. These data show that transiently boosting peripheral {gamma}{delta} T cells with ZOL+IL-2 soon after Mtb coinfection of SIV-infected MCM did not improve Mtb host defense.

immunology↗

bioRxiv2023

CD8+ cells and small viral reservoirs facilitate post-ART control of SIV in Mauritian cynomolgus macaques

Sustainable HIV remission after antiretroviral therapy (ART) withdrawal, or post-treatment control (PTC), remains a top priority for HIV treatment. We observed surprising PTC in an MHC-haplomatched cohort of MHC-M3+ SIVmac239+ Mauritian cynomolgus macaques (MCMs) initiated on ART at two weeks post-infection (wpi). For six months after ART withdrawal, we observed undetectable or transient viremia in seven of eight MCMs. In vivo depletion of CD8+ cells induced rebound in all animals, indicating the PTC was mediated, at least in part, by CD8+ cells. We found that MCMs had smaller acute viral reservoirs than a cohort of identically infected rhesus macaques, a population that rarely develops PTC. The mechanisms by which unusually small viral reservoirs and CD8+ cell-mediated virus suppression enable PTC can be investigated using this MHC-haplomatched MCM model. Further, defining the immunologic mechanisms that engender PTC in this model may identify therapeutic targets for inducing durable HIV remission in humans.

immunology↗

bioRxiv2022

Host Immunity to Mycobacterium tuberculosis Infection is Similar in Simian Immunodeficiency Virus (SIV)-infected, Antiretroviral Therapy-treated and SIV-naïve Juvenile Macaques

Pre-existing HIV infection increases tuberculosis (TB) risk in children. Antiretroviral therapy (ART) reduces, but does not abolish, this risk in children with HIV. The immunologic mechanisms involved in TB progression in both HIV-naive and HIV-infected children have not been explored. Much of our current understanding is based on human studies in adults and adult animal models. In this study, we sought to model childhood HIV/Mycobacterium tuberculosis (Mtb) coinfection in the setting of ART and characterize T cells during TB progression. Macaques equivalent to 4-8 year-old children were intravenously infected with SIVmac239M, treated with ART three months later, and coinfected with Mtb three months after initiating ART. SIV-naive macaques were similarly infected with Mtb alone. TB pathology and total Mtb burden did not differ between SIV-infected, ART-treated and SIV-naive macaques, although lung Mtb burden was lower in SIV-infected, ART-treated macaques. No major differences in frequencies of CD4+ and CD8+ T cells and unconventional T cell subsets (V{gamma}9+ {gamma}{delta} T cells, MAIT cells, and NKT cells) in airways were observed between SIV-infected, ART-treated and SIV-naive macaques over the course of Mtb infection, with the exception of CCR5+ CD4+ and CD8+ T cells which were slightly lower. CD4+ and CD8+ T cell frequencies did not differ in the lung granulomas obtained at necropsy, nor did they differ in the frequency of immune checkpoint and proliferative markers. Thus, ART treatment of juvenile macaques, three months after SIV infection, resulted in similar progression of Mtb and T cell responses compared to Mtb in SIV-naive macaques.

immunology↗

bioRxiv2022

Transient T cell expansion, activation, and proliferation in therapeutically vaccinated SIV+ macaques treated with N-803

Vaccine strategies aimed at eliciting HIV-specific CD8+ T cells are one major target of interest in HIV functional cure strategies. We hypothesized that CD8+ T cells elicited by therapeutic vaccination during antiretroviral therapy (ART) would be recalled and boosted by treatment with the IL-15 superagonist N-803 after ART discontinuation. We intravenously immunized four SIV+ Mauritian cynomolgus macaques (MCM) receiving ART with vesicular stomatitis virus (VSV), modified vaccinia virus Ankara strain (MVA), and recombinant adenovirus serotype 5 (rAd-5) vectors all expressing SIVmac239 Gag. Immediately after ART cessation, these animals received three doses of N-803. Four control animals received no vaccines or N-803. The vaccine regimen generated a high magnitude of Gag-specific CD8+ T cells that were proliferative and biased toward an effector memory phenotype. We then compared cells elicited by vaccination (Gag-specific) to cells elicited by SIV infection and unaffected by vaccination (Nef-specific). We found that N-803 treatment enhanced both the frequencies of bulk and proliferating antigen-specific CD8+ T cells elicited by vaccination and the antigen-specific CD8+ T cells elicited by SIV infection. In sum, we demonstrate that a therapeutic heterologous prime-boost-boost (HPBB) vaccine can elicit antigen-specific effector memory CD8+ T cells that are boosted by N-803.

immunology↗

bioRxiv2022

IL-15 superagonist N-803 enhances IFNγ production and alters the trafficking of MAIT cells in SIV+ macaques

Mucosal Associated Invariant T cells (MAIT cells) are innate T cells that recognize bacterial metabolites and secrete cytokines and cytolytic enzymes to destroy infected target cells. This makes MAIT cells promising targets for immunotherapy to combat bacterial infections. Here, we analyzed the effects of an immunotherapeutic agent, the IL-15 superagonist N-803, on MAIT cell activation, trafficking, and cytolytic function in macaques. We found that N-803 could activate MAIT cells in vitro and increase their ability to produce IFN{gamma} in response to bacterial stimulation. To expand upon this, we examined the phenotypes and function of MAIT cells present in samples collected from PBMC, airways (BAL), and lymph nodes (LN) from rhesus macaques that were treated in vivo with N-803. N-803 treatment led to a transient 6-7 fold decrease in the total number of MAIT cells in the peripheral blood relative to pre N-803 timepoints. Concurrent with the decrease in cells in the peripheral blood, we observed a rapid decline in the frequency of CXCR3+CCR6+ MAITs. This corresponded with an increase in the frequency of CCR6+ MAITs in BAL, and higher frequencies of ki-67+ and granzyme B+ MAITs in blood, LN, and BAL. Finally, N-803 improved the ability of MAIT cells collected from PBMC and airways to produce IFN{gamma} in response to bacterial stimulation. Overall, N-803 shows the potential to transiently alter the trafficking and enhance the antibacterial activity of MAIT cells which could be combined with other strategies to combat bacterial infections.

immunology↗

bioRxiv2022

Control of SIV infection in prophylactically vaccinated, ART-naïve macaques is required for the most efficacious CD8 T cell response during treatment with the IL-15 superagonist N-803

The IL-15 superagonist N-803 has been shown to enhance the function of CD8 T cells and NK cells. We previously found that in a subset of vaccinated, ART-naive, SIV+ rhesus macaques, N-803 treatment led to a rapid but transient decline in plasma viremia that positively correlated with an increase in the frequency of CD8 T cells. Here we tested the hypothesis that prophylactic vaccination was required for N-803 mediated suppression of SIV plasma viremia. We vaccinated rhesus macaques with a DNA prime/Ad5 boost regimen using vectors expressing SIVmac239 gag, with or without a plasmid expressing IL-12, or left them unvaccinated. Animals were then intravenously infected with SIVmac239M. Six months after infection, animals were treated with N-803. We found no differences in control of plasma viremia during N-803 treatment between vaccinated and unvaccinated macaques. Furthermore, the SIV-specific CD8 T cells displayed no differences in frequency or ability to traffic to the lymph nodes. Interestingly, when we divided the SIV+ animals based on plasma viral load set-point prior to N-803 treatment, N-803 increased the frequency of SIV-specific T cells expressing ki-67+ and granzyme B+ in animals with low plasma viremia (<104 copies/mL; SIV controllers) compared to animals with high plasma viremia (>104 copies/mL;SIV non-controllers). In addition, Gag-specific CD8 T cells from the SIV+ controllers had a greater increase in CD107a+CD8+ T cells when compared to SIV+ non-controllers. Overall, our results indicate that N-803 is most effective in SIV+ animals with a pre-existing immunological ability to control SIV replication.

immunology↗

bioRxiv2021

Spontaneous control of SIV replication does not prevent immune dysregulation and bacterial dissemination in animals co-infected with M. tuberculosis

Individuals infected with both HIV and Mycobacterium tuberculosis (Mtb) are more likely to develop severe Tuberculosis (TB) disease than HIV-naive individuals. To understand how a chronic pre-existing Simian immunodeficiency virus (SIV) infection impairs the early immune response to Mtb, we used the Mauritian cynomolgus macaque (MCM) model of SIV/Mtb co-infection. We examined the relationship between peripheral viral control and Mtb burden, Mtb dissemination, and immunological function between SIV+ spontaneous controllers, SIV+ non-controllers, and SIV-naive MCM who were challenged with a barcoded Mtb Erdman strain and necropsied six weeks post infection. Mycobacterial burden was highest in the SIV+ non-controllers in all assessed tissues. In lung granulomas, we found the frequency of CD4+ T cells producing TNF was reduced in all SIV+ MCM, but CD4+ T cells producing IFN{gamma} were only lower in the SIV+ non-controllers. Further, while all SIV+ MCM had more PD1+ and TIGIT+ T cells in the lung granulomas relative to SIV-naive MCM, SIV+ controllers exhibited the highest frequency of cells expressing these markers. To measure the effect of SIV infection on within-host bacterial dissemination, we sequenced the molecular barcodes of Mtb present in each tissue and characterized the complexity of the Mtb populations. While Mtb population complexity was not associated with infection group, lymph nodes had increased complexity when compared to lung granulomas across all groups. These results provide evidence SIV+ animals, independent of viral control, exhibit dysregulated immune responses and enhanced dissemination of Mtb, likely contributing to the poor TB disease course across all SIV/Mtb co-infected animals. ImportanceHIV and TB remain significant global health issues, despite the availability of treatments. Individuals with HIV, including those who are virally suppressed, are at an increased risk to develop and succumb to severe TB disease when compared to HIV-naive individuals. Our study aims to understand the relationship between SIV replication, mycobacterial growth, and immunological function in the tissues of co-infected Mauritian cynomolgus macaques during the early phase of Mtb infection. Here we demonstrate that increased viral replication is associated with increased bacterial burden in the tissues and impaired immunologic responses, and that the damage attributed to virus infection is not fully eliminated when animals spontaneously control virus replication.

microbiology↗

bioRxiv2020

Pre-existing SIV infection increases expression of T cell markers associated with activation during early Mycobacterium tuberculosis co-infection and impairs TNF responses in granulomas

Tuberculosis (TB) is the leading infectious cause of death among people living with HIV (PLHIV). PLHIV are more susceptible to contracting Mycobacterium tuberculosis (Mtb) infection and often have worsened TB disease. Understanding the immunologic defects caused by HIV and the consequences it has on Mtb co-infection is critical in combating this global health epidemic. We previously established a model of simian immunodeficiency virus (SIV) and Mtb co-infection in Mauritian cynomolgus macaques (MCM), and showed that SIV/Mtb co-infected MCM had rapidly progressive TB. We hypothesized that pre-existing SIV infection impairs early T cell responses to Mtb infection. To test our hypothesis, we infected MCM with SIVmac239 intrarectally followed by co-infection with a low dose of Mtb Erdman 6 months later. SIV-naive MCM were infected with Mtb alone as controls. Six weeks after Mtb infection, animals were necropsied and immune responses were measured by multiparameter flow cytometry. While the two groups exhibited similar TB progression at time of necropsy (Nx), longitudinal sampling of the blood (PBMC) and airways (BAL) revealed a significant reduction in circulating CD4+ T cells and an influx of CD8+ T cells in airways following Mtb co-infection of SIV+ animals. Differences in the activation markers CD69, PD-1, and TIGIT were observed. At sites of Mtb infection (i.e. granulomas), SIV/Mtb co-infected animals had a higher proportion of CD4+ and CD8+ T cells expressing PD-1 and TIGIT. In addition, there were fewer TNF-producing CD4+ and CD8+ T cells in granulomas and airways of SIV/Mtb co-infected animals. Taken together, we show that concurrent SIV infection alters T cell phenotypes in granulomas during the early stages of TB disease. As it is critical to establish control of Mtb replication soon after infection, these phenotypic changes may distinguish the immune dysfunction that arises from pre-existing SIV infection which promotes TB progression. Author SummaryPeople living with HIV are incredibly susceptible to TB and, when co-infected with Mtb, often develop serious TB disease. We do not yet understand precisely how HIV infection impairs the early stages of the adaptive immune response against Mtb bacilli. We employed a non-human primate model of HIV, using SIV as a surrogate for HIV, followed by Mtb co-infection to investigate the immunologic defects associated with pre-existing SIV infection over the first six weeks of Mtb co-infection. Our study focused on CD4+ and CD8+ T cells as these cells are known to play an important role in Mtb control. We found more CD8+ T cells in granulomas, the sites of Mtb infection, from SIV/Mtb co-infected animals, with little difference in CD4+ T cells. SIV/Mtb co-infected animals and animals infected with SIV alone had a higher proportion of both CD4+ and CD8+ T cells expressing activation markers compared to SIV-naive animals, consistent with SIV-dependent immune activation. Notably, we observed a lower proportion of TNF-producing T cells, a cytokine critical for Mtb control, in granulomas and airways of SIV/Mtb co-infected animals. Taken together, these data show that pre-existing SIV alters T cell phenotypes and reduces TNF responses early in Mtb infection.

immunology↗

bioRxiv2020

MAIT cells are minimally responsive to Mycobacterium tuberculosis within granulomas, but are functionally impaired by SIV in a macaque model of SIV and Mtb co-infection

Mucosal associated invariant T (MAIT) cells recognize and can directly destroy bacterially infected cells. While a role for MAIT cells has been suggested in several in vitro and in vivo models of M.tuberculosis (Mtb) infection, these studies have often focused on MAIT cells within the peripheral blood or are cross-sectional studies rather than longitudinal studies. The role of MAIT cells within granulomas and other sites of Mtb infection is relatively unknown. Furthermore, how HIV/SIV infection might impair MAIT cells at the sites of Mtb infection has not been determined. Using a Mauritian cynomolgus macaque (MCM) model system, we phenotyped MAIT cells in the peripheral blood and BAL prior to and during infection with SIVmac239. To characterize the role of MAIT cells within granulomas, SIV+ and -naive MCM were infected with a low dose of Mtb for 6 weeks. MAIT cell frequency and function was examined within the peripheral blood, distal airways, as well as within Mtb-affected lymph nodes (LN) and tissues. Surprisingly, we found no evidence of MAIT cell responsiveness to Mtb within granulomas. Additionally, MAIT cells only minimally responded to mycobacterial stimulus in ex vivo functional assays. In contrast, most MAIT cell activation seemed to occur in samples with highly active SIV replication, including blood and SIV-infected LN. Finally, the ability of MAIT cells to secrete TNF (TNF) was impaired during SIV and Mtb co-infection, indicating that the two pathogens together could have a synergistically deleterious effect on MAIT cell function. The effect of this functional impairment on overall TB disease burden was unclear, but might be deleterious if MAIT cells are needed to fully activate antimycobacterial immune cells within the granulomas.

immunology↗

bioRxiv2019

Extensive CD8β depletion does not prevent control of viral replication or protection from challenge in macaques chronically infected with a live attenuated simian immunodeficiency virus

We evaluated the contribution of CD8{beta}+ T cells on control of live-attenuated simian immunodeficiency virus (LASIV) replication during chronic infection and subsequent protection from pathogenic SIV challenge. Unlike previous reports with a CD8-specific depleting monoclonal antibody (mAb), the CD8{beta}-specific mAb CD8{beta}255R1 selectively depleted CD8{beta}+ T cells without also depleting non-CD8+ T cell populations that express CD8, such as natural killer (NK) cells and {gamma}{delta} T cells. Following infusion with CD8{beta}255R1, plasma viremia transiently increased coincident with declining peripheral CD8{beta}+ T cells. Interestingly, plasma viremia returned to pre-depletion levels even when peripheral CD8{beta}+ T cells did not. Although depletion of CD8{beta}+ T cells in the lymph node (LN) was incomplete, frequencies of these cells were three-fold lower (p=0.006) in animals that received CD8{beta}255R1 compared to control IgG. It is possible that these residual SIV-specific CD8{beta}+ T cells may have contributed to suppression of viremia during chronic infection. We also determined whether infusion of CD8{beta}255R1 in the LASIV-vaccinated animals increased their susceptibility to infection following intravenous challenge with pathogenic SIVmac239. We found that 7/8 animals infused with CD8{beta}255R1, and 3/4 animals infused with the control IgG, were resistant to SIVmac239 infection. These results suggest that infusion with CD8{beta}255R1 did not eliminate the protection afforded to LASIV vaccination. This provides a comprehensive description of the impact of CD8{beta}255R1 infusion on the immunological composition of the host, when compared to an isotype matched control IgG, while showing that the control of LASIV viremia and protection from challenge can occur even after CD8{beta}255R1 administration.\n\nImportanceStudies of SIV-infected macaques that deplete CD8+ T cells in vivo with monoclonal antibodies have provided compelling evidence for their direct antiviral role. These studies utilized CD8-specific mAbs that target both the major (CD8{beta}+) and minor (CD8+) populations of CD8+ T cells, but additionally deplete non-CD8+ T cell populations that express CD8, such as NK cells and {gamma}{delta} T cells. In the current study, we administered the CD8{beta}-specific depleting mAb CD8{beta}255R1 to cynomolgus macaques chronically infected with a LASIV to selectively deplete CD8{beta}+ T cells without removing CD8+ lymphocytes. We evaluated the impact on control of virus replication and protection from pathogenic SIVmac239 challenge. These results underscore the utility of CD8{beta}255R1 for studying the direct contribution of CD8{beta}+ T cells in various disease states.

immunology↗

bioRxiv2018

Acute-phase CD4+ T cell responses targeting invariant viral regions are associated with control of live-attenuated simian immunodeficiency virus

We manipulated SIVmac239{Delta}nef, a model of MHC-independent viral control, to evaluate characteristics of effective cellular responses mounted by Mauritian cynomolgus macaques (MCMs) who express the M3 MHC haplotype that has been associated with poor control of pathogenic SIV. We created SIV{Delta}nef-8x to test the hypothesis that effective SIV-specific T cell responses targeting invariant viral regions can emerge in the absence of immunodominant CD8+ T cell responses targeting variable epitopes, and that control is achievable in individuals lacking known protective MHC alleles. Full proteome IFN{gamma} ELISPOT assays identified six newly targeted immunogenic regions following SIV{Delta}nef-8x infection of M3/M3 MCMs. We deep sequenced circulating virus and found that four of the six newly targeted regions rarely accumulated mutations. Six animals infected with SIV{Delta}nef-8x targeted at least one of the four invariant regions and had a lower set point viral load compared to two animals that did not target any invariant regions. We found that MHC class II molecules restricted all four of the invariant peptide regions, while the two variable regions were restricted by MHC class I molecules. Therefore, in the absence of immunodominant CD8+ T cell responses that target variable regions during SIVmac239{Delta}nef infection, individuals without protective MHC alleles developed predominantly CD4+ T cell responses specific for invariant regions that may improve control of virus replication. Our results provide some evidence that antiviral CD4+ T cells during acute SIV infection can contribute to effective viral control and should be considered in strategies to combat HIV infection.\n\nImportanceStudies defining effective cellular immune responses to human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) have largely focused on a rare population that express specific MHC class I alleles and control virus replication in the absence of antiretroviral treatment. This leaves in question whether similar effective immune responses can be achieved in the larger population. The majority of HIV-infected individuals mount CD8+ T cell responses that target variable viral regions that accumulate high-frequency escape mutations. Limiting T cell responses to these variable regions and targeting invariant viral regions, similar to observations in rare elite controllers, may provide an ideal strategy for the development of effective T cell responses in individuals with diverse MHC genetics. Therefore, it is paramount to determine whether T cell responses can be redirected towards invariant viral regions in individuals without protective MHC alleles and if these responses improve control of virus replication.

immunology↗