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Immunodeficient mice reconstituted with a human immune system represent a promising tool for translational research as they may allow modeling and therapy of human diseases in vivo. However, insufficient development and function of human natural killer (NK) cells and T cell subsets limit the applicability of humanized mice for studying cancer biology and therapy. Here, we describe a human interleukin 15 (IL15) and human signal regulatory protein alpha (SIRPA) knock-in mouse on a Rag2-/- Il2rg-/- background (SRG-15). Transplantation of human hematopoietic stem and progenitor cells into SRG-15 mice dramatically improved the development and functional maturation of circulating and tissue-resident human NK and CD8+ T cells and promoted the development of tissue-resident innate lymphoid cell (ILC) subsets. Profiling of human NK cell subsets by mass cytometry revealed a highly similar expression pattern of killer inhibitory receptors and other candidate molecules in NK cell subpopulations between SRG-15 mice and humans. In contrast to nonobese diabetic severe combined immunodeficient Il2rg-/- (NSG) mice, human NK cells in SRG-15 mice did not require preactivation but infiltrated a Burkitt's lymphoma xenograft and efficiently inhibited tumor growth following treatment with the therapeutic antibody rituximab. Our humanized mouse model may thus be useful for preclinical testing of novel human NK cell-targeted and combinatory cancer immunotherapies and for studying how they elicit human antitumor immune responses in vivo. [ABSTRACT FROM AUTHOR]

The ability of individual T cells to perform multiple effector functions is crucial for protective immunity against viruses and cancer. This polyfunctionality is frequently lost during chronic infections; however, the molecular mechanisms driving T cell polyfunctionality are poorly understood. We found that human T cells stimulated by a high concentration of antigen lacked polyfunctionality and expressed a transcription profile similar to that of exhausted T cells. One specific pathway implicated by the transcription profile in control of T cell polyfunctionality was the MAPK/ERK pathway. This pathway was altered in response to different antigen concentrations, and polyfunctionality correlated with upregulation of phosphorylated ERK. T cells that were stimulated with a high concentration of antigen upregulated sprouty-2 (SPRY2), a negative regulator of the MAPK/ERK pathway. The clinical relevance of SPRY2 was confirmed by examining SPRY2 expression in HIV-specific T cells, where high levels of SPRY2 were seen in HIV-specific T cells and inhibition of SPRY2 expression enhanced the HIV-specific polyfunctional response independently of the PD-1 pathway. Our findings indicate that increased SPRY2 expression during chronic viral infection reduces T cell polyfunctionality and identify SPRY2 as a potential target for immunotherapy. [ABSTRACT FROM AUTHOR]

Human immunodeficiency virus type 1 (HIV-1) establishes a latent reservoir in resting memory CD4+ T cells. This latent reservoir is a major barrier to the eradication of HIV-1 in infected individuals and is not affected by highly active antiretroviral therapy (HAART). Reactivation of latent HIV-1 is a possible strategy for elimination of this reservoir. The mechanisms with which latency is maintained are unclear. In the analysis of the regulation of HIV-1 gene expression, it is important to consider the nature of HIV-1 integration sites. In this study, we analyzed the integration and transcription of latent HIV-1 in a primary CD4+ T cell model of latency. The majority of integration sites in latently infected cells were in introns of transcription units. Serial analysis of gene expression (SAGE) demonstrated that more than 90% of those host genes harboring a latent integrated provirus were transcriptionally active, mostly at high levels. For latently infected cells, we observed a modest preference for integration in the same transcriptional orientation as the host gene (63.8% versus 36.2%). In contrast, this orientation preference was not observed in acutely infected or persistently infected cells. These results suggest that transcriptional interference may be one of the important factors in the establishment and maintenance of HIV-1 latency. Our findings suggest that disrupting the negative control of HIV-1 transcription by upstream host promoters could facilitate the reactivation of latent HIV-1 in some resting CD4+ T cells. [ABSTRACT FROM AUTHOR]

The development of highly active antiretroviral therapy (HAART) to treat individuals infected with HIV-1 has dramatically improved patient outcomes, but HAART still fails to cure the infection. The latent viral reservoir in resting CD4+ T cells is a major barrier to virus eradication. Elimination of this reservoir requires reactivation of the latent virus. However, strategies for reactivating HIV-1 through nonspecific T cell activation have clinically unacceptable toxicities. We describe here the development of what we believe to be a novel in vitro model of HIV-1 latency that we used to search for compounds that can reverse latency. Human primary CD4+ T cells were transduced with the prosurvival molecule Bcl-2, and the resulting cells were shown to recapitulate the quiescent state of resting CD4+ T cells in vivo. Using this model system, we screened small-molecule libraries and identified a compound that reactivated latent HIV-1 without inducing global T cell activation, 5-hydroxynaphthalene-1,4-dione (5HN). Unlike previously described latency-reversing agents, 5HN activated latent HIV-1 through ROS and NF-kappaB without affecting nuclear factor of activated T cells (NFAT) and PKC, demonstrating that TCR pathways can be dissected and utilized to purge latent virus. Our study expands the number of classes of latency-reversing therapeutics and demonstrates the utility of this in vitro model for finding strategies to eradicate HIV-1 infection. [ABSTRACT FROM AUTHOR]

The latent reservoir of HIV-1 is a major barrier for viral eradication. Potent HIV-1 broadly neutralizing antibodies (bNabs) have been used to prevent and treat HIV-1 infections in animal models and clinical trials. Combination of bNabs and latency-reversing agents (LRAs) is considered a promising approach for HIV-1 eradication. PCR-based assays that can rapidly and specifically measure singly spliced HIV-1 vpu/env mRNA are needed to evaluate the induction of the viral envelope production at the transcription level and bNab-mediated reservoir clearance. Here, we reported a PCR-based method to accurately quantify the production of intracellular HIV-1 vpu/env mRNA. With the vpu/env assay, we determined the LRA combinations that could effectively induce vpu/env mRNA production in CD41 T cells from antiretroviral therapy (ART)-treated individuals. None of the tested LRAs were effective alone. A comparison between the quantitative viral outgrowth assay (Q-VOA) and the vpu/env assay showed that vpu/env mRNA production was closely associated with the reactivation of replication-competent HIV-1, suggesting that vpu/env mRNA was mainly produced by intact viruses. Finally, antibody-mediated killing in HIV-1-infected humanized mice demonstrated that the vpu/env assay could be used to measure the reduction of infected cells in tissues and was more accurate than the commonly used gag-based PCR assay, which measures unspliced viral genomic RNA. In conclusion, the vpu/env assay allows convenient and accurate assessment of HIV-1 latency reversal and bNab-mediated therapeutic strategies. [ABSTRACT FROM AUTHOR]

Identifying cellular reservoirs of human immunodeficiency virus type 1 (HIV-1) in patients on antiretroviral therapy (ART) is critical to finding a cure for HIV-1. In addition to resting CD4+ T cells, CD34+ hematopoietic progenitor cells have been proposed as another reservoir. We obtained bone marrow aspirates from 11 patients on ART who had undetectable plasma HIV-1 RNA. HIV-1 DNA was detected in CD4+ T cells from peripheral blood in all patients and from bone marrow cellular fractions containing T cells in most patients. We did not find HIV-1 DNA in highly purified CD34+ populations using either a sensitive real-time polymerase chain reaction assay or a coculture assay for replication-competent HIV-1. [ABSTRACT FROM AUTHOR]

Highly active antiretroviral therapy (HAART) can reduce plasma HIV-1 levels to below the detection limit. However, due to the latent reservoir in resting CD4+ cells, HAART is not curative. Elimination of this reservoir is critical to curing HIV-1 infection. Agents that reactivate latent HIV-1 through nonspecific T cell activation are toxic. Here we demonstrate in a primary CD4+ T cell model that the FDAapproved drug disulfiram reactivates latent HIV-1 without global T cell activation. The extent to which disulfiram reactivates latent HIV-1 in patient cells is unclear, but the drug alone or in combination may be useful in future eradication strategies. [ABSTRACT FROM AUTHOR]