Mechanisms for HIV containment in CD4 T cells under homeostatic proliferation
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ABSTRACT: The main obstacle in curing an established HIV-1 infection is the long-lived reservoir of latently infected CD4+ T cells. This reservoir is maintained by T cell expansion that can be activated by several mechanisms including antigen-driven proliferation and homeostatic proliferation (HSP). Antigen-driven proliferation triggered by T cell receptor (TCR) signaling is a strong physiological inducer of CD4+ T cell expansion. This also reactivates latent HIV-1 and thus, can be the source of viral rebound. Unlike antigen-driven proliferation, HSP allows the expansion of HIV-1-infected CD4+ T cells without activating HIV-1 expression. While this condition strongly activates STAT5 signaling, the mechanisms for HIV-1 containment are unknown. Our previous work using HIV-infected primarily CD4+ T cells maintained under HSP conditions suggested a post-transcriptional block as a cause of the containment (Tsunetsugu-Yokota et al. 2016 Front Microbiol). To decipher the mechanisms that contribute to the HIV-1 refractory state in homeostatic proliferating CD4+ T cells, we analyzed differentially expressed genes in primary CD4 + cells that were cultured either under HSP conditions (culture with IL-7 and IL-15) or after TCR-stimulation (culture with IL-2 after anti-CD3/CD28 activation).
Project description:The size of lentiviral DNA reservoirs reflects effectiveness of immune responses against lentiviruses. So far, abundant information has been gathered on the control of HIV-1 replication. Understanding of innate mechanisms contributing to containment of HIV-DNA reservoir, however, are only partly clarified and are relevant to guide interventions for reservoir containment or eradication. We studied the contribution of Natural Killer (NK) cell functional features in HIV patients either controlling replication either spontaneously (HIC) or after progression and antiretroviral treatment (PP). An inverse correlation between HIV-DNA copy numbers (either total or integrated) in circulating CD4+ cells and NK cell function were observed. Induced IFN-gamma production and NKp46/NKp30 activating receptor-induced expression correlated inversely with reservoir size. The correlation was present not only when considering a homogeneous cohort of HIC patients, but also when PP patients were included in the analysis. Adaptive (NKG2C + CD57 + ) NK cell features were not associated with reservoir size. However a distinct set of 370 differentially expressed transcripts was found to underlie functional differences in NK cells controlling HIV-DNA reservoir size. In proof-of-principle in vitro experiments of CD4+ cell infection with HIV-1, purified NK cells with the above functional/transcriptional features displayed a 10- and 30-fold higher ability to control HIV replication and DNA burden in vitro, respectively, compared to other NK cells. Thus, NK cells with a specific functional and transcriptional signature contribute to control of HIV reservoir in CD4+ cells. Their selection, expansion and/or adoptive transfer may support strategies to eradicate HIV-1 infection or to safely deescalate antiretroviral treatment.
Project description:Despite antiretroviral therapy (ART), HIV-1 persists in latently-infected CD4+ T cells, preventing cure. Antigen (Ag) drives proliferation of infected cells, preventing latent reservoir decay. However, the relationship between antigen recognition and HIV-1 gene expression is poorly understood since most studies of latency reversal use agents that induce non-specific global T cell activation. Here, we isolated rare CD4+ T cells responding to cytomegalovirus (CMV) or HIV-1 Gag antigens from participants on long-term ART and assessed T cell activation and HIV-1 RNA expression upon co-culture with autologous dendritic cells (DCs) presenting cognate antigens. Physiological presentation of cognate antigens induced broad T cell activation (median 42-fold increase in CD154+CD69+ cells) and significantly increased HIV-1 transcription (median 4-fold), mostly through the induction of rare cells with higher viral expression. Thus, despite low proviral inducibility, physiologic antigen recognition can promote HIV-1 expression, potentially contributing to spontaneous reservoir activity on ART and viral rebound upon ART interruption. Additionally, we observed striking differences in the transcriptome profiles of Ag-responding CD4+ T cells after stimulations with Ag or global T cell activators. This analysis revealed quantitative differences between NFAT and NFkB target genes and may guide future approaches to Ag-mediated HIV-1 latency reversal.
Project description:The clonal expansion of HIV-1-infected CD4+ T cells is a major barrier to cure. Using single-cell ECCITE-seq, we examined the transcriptional landscape, upstream immune regulators, HIV-1 RNA expression, and T cell clonal expansion dynamics of 215,458 CD4+ T cells (267 HIV-1 RNA+ cells and 68 expanded HIV-1 RNA+ T cell clones) from six HIV-1-infected individuals (during viremia and after suppressive antiretroviral therapy) and two uninfected individuals, in unstimulated conditions and after CMV and HIV-1 antigen stimulation. We found that despite antiretroviral therapy, antigen and TNF responses persisted and shaped T cell clonal expansion. HIV-1 resided in Th1 polarized, antigen-responding T cells expressing Bcl-2 family anti-apoptotic genes. HIV-1 RNA+ T cell clones were larger in clone size, established during viremia, persistent after viral suppression, and enriched in GZMB+ cytotoxic effector memory Th1 cells. Targeting HIV-1-infected cytotoxic CD4+ T cells and drivers of clonal expansion provides a new direction for HIV-1 eradication.
Project description:Hematopoietic stem cell transplantation from a donor whose T cells did not express CCR5—a co-receptor for HIV—resulted in an apparent cure of an HIV-infected adult1. Herein, we have exploited this strategy by adoptive transfer of autologous CCR5 gene disrupted CD4+ T cells (SB-728-T) in 9 HIV+ participants. A single infusion of SB-728-T, a minimally invasive intervention, led to sustained increases in CD4+ T cell counts through 3.5 years (33-44 months) compared to baseline (median increase of +193 cells/µl, P = 0.02). The degree of long-term immune reconstitution was associated with expansion of a polyclonal stem cell-like CCR5-depleted CD4+ T cell population. SB-728-T therapy was also associated with expansion of polyfunctional HIV-specific CD8+ T cells (P = 0.03) and decline in size of the HIV reservoir (-0.23 to -3.6 log decrease). Collectively, these data suggest that generation and protection of CD4 memory cells will improve T cell homeostasis, enhance HIV-specific immunity, and accelerate the decline of the host HIV reservoir.
Project description:Suppressive HAART does not eradicate HIV-1 and viral DNA persists as a stably integrated form in the absence of viral particle production. As a consequence, latent reservoirs are refractory to antiretroviral drugs and invisible to immune surveillance. The largest latent reservoir consists of resting memory CD4+ T cells. These cells can resume viral infection when activated through antigen recognition, causing bursts of viremia (blips). Current therapies targeting latent HIV-1 have focused primarily on the M-bM-^@M-^\shock and killM-bM-^@M-^] approach, which employs M-bM-^@M-^\anti-latencyM-bM-^@M-^] drugs M-bM-^@M-^S most notably histone deacetylase (HDAC) inhibitors M-bM-^@M-^S to reactivate and flush latent provirus from its cellular reservoirs in the absence of global T cell activation. This approach is predicated on the notions that viral reactivation will lead to the demise of the infected cell, and that HAART will prevent spreading of the infection. On the contrary, recent evidence indicates that latently infected CD4+ T cells of HIV-1 patients on HAART survive in vitro viral reactivation with the HDAC inhibitor, SAHA, even when co-cultured with autologous CD8+ cytotoxic T lymphocytes (CTL). Moreover, it remains to be addressed the impact of anti-latency drugs on viral reservoirs undergoing low-level ongoing replication, inherently more resistant to the cytopathic effects of HIV-1 and residing in anatomical sites hard to reach for some antiretroviral drugs (e.g. macrophages). As a consequence, there is a need to develop alternative therapeutic approaches aimed at eliminating or decreasing the latent reservoir. Progress in that direction has been hindered by the lack of biomarkers uniquely or differentially expressed on latently infected compared to their uninfected counterparts. To gain insight into the cellular mechanisms that take place in the context of latency, and with the goal of identifying distinctive markers that distinguish latently infected CD4+ T cells, we have used an in vitro model developed in our laboratory to study the expression profile of latently infected CD4+ T cells by microarray analysis. We have used a culture system, previously established in our laboratory, to generate and isolate quiescent latently infected CD4+ T cells in vitro. In this in vitro HIV-1 latency model, CD4+ T cells are activated, infected with full length, replication competent HIV-1, and then returned to quiescence in the presence of IL-7, yielding a culture of quiescent latently infected and uninfected cells. We showed that HIV-1 p24gag expressed during viral replication persists in the cytoplasm of latently infected cells for several days before being degraded. Therefore, we exploited the presence of cytoplasmic p24gag to sort latently infected from uninfected cells by FACS from the same initial cell culture. Total RNA was isolated from sorted latently infected and uninfected cells generated from CD4+ T cells of four different donors. Paired RNA samples from infected and uninfected cells were labeled with Cy3 and Cy5 to allow dual-color competitive hybridization. Moreover, to control for the dye bias in our experiments, we implemented a dye swap protocol (reciprocal labeling) for paired RNA samples from 2 donors. Samples were analyzed by dual-color competitive hybridization on the Agilent whole human genome microarrays (41,000 unique probes). This is the first comparative genomic profiling of primary latently infected resting memory CD4+ T cells versus their uninfected counterparts sorted from the same culture. Microarray analyses performed in this study revealed profound differences between latently infected and uninfected cells. Of relevance are genes involved, not only in previously described pathways related with transcriptional and post-transcriptional regulation, but affecting proliferation, survival, cell cycle progression and cell metabolism. This could explain why latently infected cells have been resistant to reactivation with current anti-latency approaches. Thus, targeting of more downstream steps, such as the ones identified in this study, may be able to enhance viral flushing from refractory latent reservoirs. In addition, we identified a panel of surface makers differentially expressed in latently infected cells, which seem worth investigating for their potential use as biomarkers. Indeed, they might allow the enrichment of this latent reservoir for molecular in depth studies, for monitoring the size of the latent reservoir in the clinical setting, as well as for the development of new therapeutic strategies aimed at eradicating this reservoir.
Project description:T follicular helper cells (TFH) are critical for the development and maintenance of germinal centers (GC) and humoral immune responses. During chronic HIV/SIV infection TFH accumulate, possibly as a result of antigen persistence. The HIV/SIV-associated TFH expansion may also reflect lack of regulation by suppressive follicular regulatory CD4+ T-cells (TFR). TFR are natural regulatory T-cells (TREG) that migrate into the follicle and, similarly to TFH, up-regulate CXCR5, Bcl-6, and PD1. Here we identified TFR as CD4+CD25+FoxP3+CXCR5+PD1hiBcl-6+ within lymph nodes of rhesus macaques (RM) and confirmed their localization within the GC by immunohistochemistry. RNA sequencing showed that TFR exhibit a distinct transcriptional profile with shared features of both TFH and TREG, including intermediate expression of FoxP3, Bcl-6, PRDM1, IL-10, and IL-21. In healthy, SIV-uninfected RM, we observed a negative correlation between frequencies of TFR and both TFH and GC B-cells as well as levels of CD4+ T-cell proliferation. Following SIV infection, the TFR/TFH ratio was reduced with no change in the frequency of TREG or TFR within the total CD4+ T-cell pool. Finally, we examined whether higher levels of direct virus infection of TFR were responsible for their relative depletion post-SIV infection. We found that TFH, TFR and TREG sorted from SIV- infected RM harbor comparable levels of cell-associated viral DNA. Our data suggests that TFR may contribute to the regulation and proliferation of TFH and GC B-cells in vivo and that a decreased TFR/TFH ratio in chronic SIV infection may lead to unchecked expansion of both TFH and GC B-cells. TFR, TFH, TREG and bulk CD4 cells were sorted from spleens of 5 uninfected and 5 infected RM.
Project description:Understanding the complexity of the long-lived HIV reservoir during antiretroviral therapy (ART) remains a major impediment for HIV cure research. To address this, we developed single-cell viral ASAPseq to precisely define the unperturbed peripheral blood HIV-infected memory CD4+ T cell reservoir from antiretroviral treated people living with HIV (ART-PLWH) via the presence of integrated accessible proviral DNA in concert with epigenetic and cell surface protein profiling. We identified profound reservoir heterogeneity within and between ART-PLWH, characterized by novel and known surface markers within total and individual memory CD4+ T cell subsets. We further uncovered novel epigenetic profiles and transcription factor motifs enriched in HIV-infected cells that suggest infected cells with accessible provirus, irrespective of reservoir distribution, are poised for reactivation during ART treatment. Together, our findings reveal the extensive inter- and intrapersonal cellular heterogeneity of the HIV reservoir, and establish an initial multiomic atlas to develop targeted reservoir elimination strategies.
Project description:HIV-1 usually utilize CCR5 as the co-receptor and rarely switches to CXCR4-tropic until late stage of infection. CCR5+CD4+ T cells are the major virus-producing cells in patients as well as SIV-infected non-human primates. The differentiation of CCR5+CD4+ T cells is associated with the availability of IL-15, which increases during acute HIV-1 infection. Here, we report that CCR5 is expressed by CD4+ T cells exhibiting effector or effector memory phenotype with high expression levels of the IL-2/IL-15 receptor common beta and gamma chains. IL-15 but not IL-7 improves the survival of CCR5+CD4+ T cells, drives their expansion, and facilitates HIV-1 infection in vitro and in humanized mice. Our study suggests that IL-15 plays confounding roles in HIV-1 infection, and future studies on the IL-15-based boosting of anti-HIV-1 immunity should carefully exam the potential effects on the expansion of HIV-1 reservoirs in CCR5+CD4+ T cells.
Project description:Elite Long-Term Nonprogressors are asymptomatic HIV-infected individuals who display long-term virtually undetectable viremia, stable CD4 T cell counts and extremeley low levels of HIV reservoir, in the absence of antiretroviral therapy. We conducted a whole-genome transcriptional profiling study of sorted resting CD4 T cell subsets (naive, central memory, transitional memory and effector memory) in 7 Elite Long-Term Nonprogressors, 7 HIV-infected viremic and 7 uninfected individuals. HIV-1 cellular DNA levels were quantified in each sorted CD4 T cell subset
Project description:Wodarz2007 - HIV/CD4 T-cell interaction
A deterministic model illustrating how
CD4 T-cells can influence HIV infection.
This model is described in the article:
Infection dynamics in
HIV-specific CD4 T cells: does a CD4 T cell boost benefit the
host or the virus?
Wodarz D, Hamer DH.
Math Biosci 2007 Sep; 209(1):
14-29
Abstract:
Recent experimental data have shown that HIV-specific CD4 T
cells provide a very important target for HIV replication. We
use mathematical models to explore the effect of specific CD4 T
cell infection on the dynamics of virus spread and immune
responses. Infected CD4 T cells can provide antigen for their
own stimulation. We show that such autocatalytic cell division
can significantly enhance virus spread, and can also provide an
additional reservoir for virus persistence during anti-viral
drug therapy. In addition, the initial number of HIV-specific
CD4 T cells is an important determinant of acute infection
dynamics. A high initial number of HIV-specific CD4 T cells can
lead to a sudden and fast drop of the population of
HIV-specific CD4 T cells which results quickly in their
extinction. On the other hand, a low initial number of
HIV-specific CD4 T cells can lead to a prolonged persistence of
HIV-specific CD4 T cell help at higher levels. The model
suggests that boosting the population of HIV-specific CD4 T
cells can increase the amount of virus-induced immune
impairment, lead to less efficient anti-viral effector
responses, and thus speed up disease progression, especially if
effector responses such as CTL have not been sufficiently
boosted at the same time.
This model is hosted on
BioModels Database
and identified by:
BIOMD0000000663.
To cite BioModels Database, please use:
Chelliah V et al. BioModels: ten-year
anniversary. Nucl. Acids Res. 2015, 43(Database
issue):D542-8.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.