Article

Suppression of HIV-specific T cell activity by lymph node CD25(+) regulatory T cells from HIV-infected individuals

Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 03/2007; 104(9):3390-5. DOI: 10.1073/pnas.0611423104
Source: PubMed

ABSTRACT

CD25(+) CD4(+) FoxP3(+) regulatory T (Treg) cells isolated from the peripheral blood of asymptomatic HIV-infected individuals have been demonstrated to significantly suppress HIV-specific immune responses in vitro. CD25(+) Treg cell suppressor activity in the peripheral blood seems to diminish with progression of HIV disease, and it has been suggested that loss of Treg cells contributes to aberrant immune activation and disease progression. However, phenotypic studies suggest that Treg cells may migrate to, and be maintained or even expanded in, tissue sites of HIV replication. Currently, it is not known whether tissue-associated Treg cells maintain suppressive activity in the context of HIV infection, particularly in individuals with advanced disease. The present study demonstrates that CD25(+) Treg cells isolated from lymph nodes and peripheral blood of HIV(+) subjects, even those with high viral loads and/or low CD4(+) T cell counts, maintain potent suppressive activity against HIV-specific cytolytic T cell function. This activity was better in lymph node as compared with peripheral blood, particularly in patients with high levels of plasma viremia. In addition, the expression of certain CD25(+) Treg-associated markers on CD4(+) T cells isolated from lymph nodes differed significantly from those on CD4(+) T cell subsets isolated from the peripheral blood. These data suggest that CD25(+) Treg cell-mediated suppression of HIV-specific responses continues throughout the course of HIV disease and, because of their particularly potent suppression of HIV-specific CTL activity in lymphoid tissue, may considerably impact the ability to control HIV replication in vivo.

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    • "Thus, hyperactivation of the immune system is considered a reliable predictor of AIDS progression [5]. The role of Treg cells in HIV-1 infection is critical because of their potential capacity to suppress HIV-1-specific immune responses [6] , but also for their implication preventing hyperactivation of immune system and suppressing chronic inflammation [7,8]. We demonstrated that HIV-1 not only directly infects Treg cells, but also deregulates the function and phenotype that define these cells [9,10]. "
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    ABSTRACT: Background: HIV-1 has proved to infect regulatory T cells (Treg) modifying their phenotype and impairing their suppressive capacity. As Treg cells are a crucial component in the preservation of the immune homeostasis, we researched that the antiviral capacity of carboxilan dendrimers prevents the HIV-1 infection of Treg and their effects. The phenotype and suppressive capacity of Treg treated or non-treated with carbosilane dendrimers were studied by flow cytometry. Treated and non-treated Treg from healthy donors were infected with HIV-1NL4.3. The infection of Treg cells by HIV-1, and protective effect of two dendrimers were determined by measuring antigen p24gag in the supernatant of the culture and intracellular. Results: The Treg cells were treated with cationic and anionic carbosilane dendrimers. The results showed that both dendrimers did not modify the phenotype and functionality of Treg cells compared with non- treated Treg cells. Anionic dendrimers showed high biocompatibility with normal activity of the Treg cells and in antiviral assays. These dendrimers were highly active against HIV-1 preventing the infection of Treg, and were able to protect the Treg from the Foxp3 downregulation induced by the HIV-1 infection. Conclusions: This is the first work showing that the in vitro use of anionic dendrimers prevent the HIV-1 replication and the infection of expanded Treg cells in culture, which raises the possibility to use Treg cells therapeutically in HIV-1-infected subjects.
    Full-text · Article · Jan 2016 · PLoS ONE
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    • "In this context, Treg activity could have a beneficial effect through suppression of generalized chronic immune activation, but also through inhibition of activated CD4+ T cells and subsequent control of viral replication, as demonstrated by Moreno-Fernandez et al. [8]. In contrast, Tregs may play a detrimental role through inhibition of anti-HIV-1 immune responses [9], [10], [11], [12], thus promoting HIV-1 persistence at the host's expense. HIV-1 infection appears to directly and indirectly modulate Tregs in vivo, as suggested by data demonstrating that individuals with chronic HIV-1 infection have higher Treg frequencies than individuals who control HIV-1 infection and healthy control subjects [13], [14]. "
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    ABSTRACT: While modulation of regulatory T cell (Treg) function and adoptive Treg transfer are being explored as therapeutic modalities in the context of autoimmune diseases, transplantation and cancer, their role in HIV-1 pathogenesis remains less well defined. Controversy persists regarding their beneficial or detrimental effects in HIV-1 disease, which warrants further detailed exploration. Our objectives were to investigate if functional CD4(+) Tregs can be isolated and expanded from HIV-1-infected individuals for experimental or potential future therapeutic use and to determine phenotype and suppressive capacity of expanded Tregs from HIV-1 positive blood and tissue. Tregs and conventional T cell controls were isolated from blood and gut-associated lymphoid tissue of individuals with HIV-1 infection and healthy donors using flow-based cell-sorting. The phenotype of expanded Tregs was assessed by flow-cytometry and quantitative PCR. T-cell receptor ß-chain (TCR-β) repertoire diversity was investigated by deep sequencing. Flow-based T-cell proliferation and chromium release cytotoxicity assays were used to determine Treg suppressive function. Tregs from HIV-1 positive individuals, including infants, were successfully expanded from PBMC and GALT. Expanded Tregs expressed high levels of FOXP3, CTLA4, CD39 and HELIOS and exhibited a highly demethylated TSDR (Treg-specific demethylated region), characteristic of Treg lineage. The TCRß repertoire was maintained following Treg expansion and expanded Tregs remained highly suppressive in vitro. Our data demonstrate that Tregs can be expanded from blood and tissue compartments of HIV-1+ donors with preservation of Treg phenotype, function and TCR repertoire. These results are highly relevant for the investigation of potential future therapeutic use, as currently investigated for other disease states and hold great promise for detailed studies on the role of Tregs in HIV-1 infection.
    Full-text · Article · Feb 2014 · PLoS ONE
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    • "The role of this cell population during HIV infection is controversial. It has been proposed that excessive immune suppression by Treg cells might be responsible for the faster progression on HIV pathogenesis (Kinter et al., 2007). On the other hand, Treg cells might protect individuals from the deleterious effects of chronic immune activation that is typically observed in HIV infection (Belkaid and Rouse, 2005; Fazekas de St Groth and Landay, 2008). "
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    ABSTRACT: The natural course of human immunodeficiency virus (HIV) infection is characterized by high viral load, depletion of immune cells, and immunodeficiency, ultimately leading to acquired immunodeficiency syndrome phase and the occurrence of opportunistic infections and diseases. Since the discovery of HIV in the early 1980s a naturally selected population of infected individuals has been emerged in the last years, characterized by being infected for many years, with viremia constantly below detectable level and poor depletion of immune cells. These individuals are classified as "elite controllers (EC) or suppressors" and do not develop disease in the absence of anti-retroviral therapy. Unveiling host factors and immune responses responsible for the elite status will likely provide clues for the design of therapeutic vaccines and functional cures. Scope of this review was to examine and discuss differences of the cell-mediated immune responses between HIV+ individuals with disease progression and EC.
    Full-text · Article · Apr 2013 · Frontiers in Immunology
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