Tumor cell-derived exosomes (TEX) suppress functions of immune cells. Here, changes in the gene profiles of primary human T lymphocytes exposed in vitro to exosomes were evaluated. CD4(+) Tconv, ...CD8(+) T or CD4(+) CD39(+) Treg were isolated from normal donors' peripheral blood and co-incubated with TEX or exosomes isolated from supernatants of cultured dendritic cells (DEX). Expression levels of 24-27 immune response-related genes in these T cells were quantified by qRT-PCR. In activated T cells, TEX and DEX up-regulated mRNA expression levels of multiple genes. Multifactorial data analysis of ΔCt values identified T cell activation and the immune cell type, but not exosome source, as factors regulating gene expression by exosomes. Treg were more sensitive to TEX-mediated effects than other T cell subsets. In Treg, TEX-mediated down-regulation of genes regulating the adenosine pathway translated into high expression of CD39 and increased adenosine production. TEX also induced up-regulation of inhibitory genes in CD4(+) Tconv, which translated into a loss of CD69 on their surface and a functional decline. Exosomes are not internalized by T cells, but signals they carry and deliver to cell surface receptors modulate gene expression and functions of human T lymphocytes.
The C-type lectin CD161 is expressed by a large proportion of human T lymphocytes of all lineages, including a population known as mucosal-associated invariant T (MAIT) cells. To understand whether ...different T cell subsets expressing CD161 have similar properties, we examined these populations in parallel using mass cytometry and mRNA microarray approaches. The analysis identified a conserved CD161++/MAIT cell transcriptional signature enriched in CD161+CD8+ T cells, which can be extended to CD161+ CD4+ and CD161+TCRγδ+ T cells. Furthermore, this led to the identification of a shared innate-like, TCR-independent response to interleukin (IL)-12 plus IL-18 by different CD161-expressing T cell populations. This response was independent of regulation by CD161, which acted as a costimulatory molecule in the context of T cell receptor stimulation. Expression of CD161 hence identifies a transcriptional and functional phenotype, shared across human T lymphocytes and independent of both T cell receptor (TCR) expression and cell lineage.
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•CD161 expression defines specific T cell subsets, including CD8+, CD4+, and TCRγδ+•CD161-expressing lymphocytes possess a conserved transcriptional signature•CD161-expressing lymphocytes display a shared innate response to IL-12+18•CD161 can act as a costimulatory receptor
T lymphocytes are conventionally divided into subsets based on expression of coreceptors, cytokines, and surface molecules. Using CyTOF and mRNA microarray analysis, Fergusson et al. identify T lymphocytes that express the C-type lectin CD161 to share a transcriptional profile and innate function across these previously defined subsets.
Regulatory T cells (Treg) and tumor-exosomes are thought to play a role in preventing the rejection of malignant cells in patients bearing nasopharyngeal carcinoma (NPC).
Treg recruitment by exosomes ...derived from NPC cell lines (C15/C17-Exo), exosomes isolated from NPC patients' plasma (Patient-Exo), and CCL20 were tested in vitro using Boyden chamber assays and in vivo using a xenograft SCID mouse model (n = 5), both in the presence and absence of anti-CCL20 monoclonal antibodies (mAb). Impact of these NPC exosomes (NPC-Exo) on Treg phenotype and function was determined using adapted assays (FACS, Q-PCR, ELISA, and MLR). Experiments were performed in comparison with exosomes derived from plasma of healthy donors (HD-Exo). The Student's t test was used for group comparisons. All statistical tests were two-sided.
CCL20 allowed the intratumoral recruitment of human Treg. NPC-Exo also facilitated Treg recruitment (3.30 ± 0.34 fold increase, P < .001), which was statistically significantly inhibited (P < .001) by an anti-CCL20 blocking mAb. NPC-Exo also recruited conventional CD4(+)CD25(-) T cells and mediated their conversion into inhibitory CD4(+)CD25(high) cells. Moreover, NPC-Exo enhanced (P = .0048) the expansion of human Treg, inducing the generation of Tim3(Low) Treg with increased expression of CD25 and FOXP3. Finally, NPC-Exo induced an overexpression of cell markers associated with Treg phenotype, properties and recruitment capacity. For example, GZMB mean fold change was 21.45 ± 1.75 (P < .001). These results were consistent with a stronger suppression of responder cells' proliferation and the secretion of immunosuppressive cytokines (IL10, TGFB1).
Interactions between NPC-Exo and Treg represent a newly defined mechanism that may be involved in regulating peripheral tolerance by tumors and in supporting immune evasion in human NPC.
Interleukin 7 (IL-7) is a common gamma chain receptor cytokine implicated in thymopoiesis and in peripheral expansion and survival of T lymphocytes. The safety and activity of recombinant human IL-7 ...(rhIL-7) administration were therefore examined in HIV-infected persons. In this prospective randomized placebo-controlled study, a single subcutaneous dose of rhIL-7 was well tolerated with biologic activity demonstrable at 3 μg/kg and a maximum tolerated dose of 30 μg/kg. Injection site reactions and transient elevations of liver function tests were the most notable side effects. Transient increases in plasma HIV-RNA levels were observed in 6 of 11 IL-7–treated patients. Recombinant hIL-7 induced CD4 and CD8 T cells to enter cell cycle; cell-cycle entry was also confirmed in antigen-specific CD8 T cells. Administration of rhIL-7 led to transient down-regulation of the IL-7 receptor alpha chain (CD127) in both CD4+ and CD8+ T cells. Single-dose rhIL-7 increased the numbers of circulating CD4+ and CD8+ T cells, predominantly of central memory phenotype. The frequency of CD4+ T cells with a regulatory T-cell phenotype (CD25high CD127low) did not change after rhIL-7 administration. Thus, rhIL-7 has a biologic and toxicity profile suggesting a potential for therapeutic trials in HIV infection and other settings of lymphopenia. This clinical trial has been registered at http://www.clinicaltrials.gov under NCT0099671.
Most of the immunoglobulin A (IgA) in the gut is generated by B cells in the germinal centers of Peyer's patches through a process that requires the presence of CD4⁺ follicular B helper T(TFH) cells. ...The nature of these TFH cells in Peyer's patches has been elusive. Here, we demonstrate that suppressive Foxp3⁺CD4⁺ T cells can differentiate into TFH cells in mouse Peyer's patches. The conversion of Foxp3⁺ T cells into TFH cells requires the loss of Foxp3 expression and subsequent interaction with B cells. Thus, environmental cues present in gut Peyer's patches promote the selective differentiation of distinct helper T cell subsets, such as TFH cells.
T-cell receptor (TCR) diversity, a prerequisite for immune system recognition of the universe of foreign antigens, is generated in the first two decades of life in the thymus and then persists to an ...unknown extent through life via homeostatic proliferation of naïve T cells. We have used next-generation sequencing and nonparametric statistical analysis to estimate a lower bound for the total number of different TCR beta (TCRB) sequences in human repertoires. We arrived at surprisingly high minimal estimates of 100 million unique TCRB sequences in naïve CD4 and CD8 T-cell repertoires of young adults. Naïve repertoire richness modestly declined two-to fivefold in healthy elderly. Repertoire richness contraction with age was even less pronounced for memory CD4 and CD8 T cells. In contrast, age had a major impact on the inequality of donai sizes, as estimated by a modified Gini-Simpson index clonality score. In particular, large naïve T-cell clones that were distinct from memory clones were found in the repertoires of elderly individuals, indicating uneven homeostatic proliferation without development of a memory cell phenotype. Our results suggest that a highly diverse repertoire is maintained despite thymic involution; however, peripheral fitness selection of T cells leads to repertoire perturbations that can influence the immune response in the elderly.
The immune system of patients infected by SARS-CoV-2 is severely impaired. Detailed investigation of T cells and cytokine production in patients affected by COVID-19 pneumonia are urgently required. ...Here we show that, compared with healthy controls, COVID-19 patients' T cell compartment displays several alterations involving naïve, central memory, effector memory and terminally differentiated cells, as well as regulatory T cells and PD1
CD57
exhausted T cells. Significant alterations exist also in several lineage-specifying transcription factors and chemokine receptors. Terminally differentiated T cells from patients proliferate less than those from healthy controls, whereas their mitochondria functionality is similar in CD4
T cells from both groups. Patients display significant increases of proinflammatory or anti-inflammatory cytokines, including T helper type-1 and type-2 cytokines, chemokines and galectins; their lymphocytes produce more tumor necrosis factor (TNF), interferon-γ, interleukin (IL)-2 and IL-17, with the last observation implying that blocking IL-17 could provide a novel therapeutic strategy for COVID-19.
Experimental autoimmune encephalomyelitis is a model for multiple sclerosis. Here we show that induction generates successive waves of clonally expanded CD4
, CD8
and γδ
T cells in the blood and ...central nervous system, similar to gluten-challenge studies of patients with coeliac disease. We also find major expansions of CD8
T cells in patients with multiple sclerosis. In autoimmune encephalomyelitis, we find that most expanded CD4
T cells are specific for the inducing myelin peptide MOG
. By contrast, surrogate peptides derived from a yeast peptide major histocompatibility complex library of some of the clonally expanded CD8
T cells inhibit disease by suppressing the proliferation of MOG-specific CD4
T cells. These results suggest that the induction of autoreactive CD4
T cells triggers an opposing mobilization of regulatory CD8
T cells.
Abstract Cytotoxic T Lymphocyte Antigen 4 (CTLA4) blockade has shown antitumor activity against common cancers. However, the exact mechanism of immune mediation by anti-CTLA4 remains to be ...elucidated. Further understanding of how CTLA4 blockade with tremelimumab mediates immune responses may allow a more effective selection of responsive patients. Our results show that tremelimumab enhanced the proliferative response of T effector cells (Teff) upon TCR stimulation, and abrogated Treg suppressive ability. In the presence of tremelimumab, frequencies of IL-2-secreting CD4+ T cells and IFN-γ-secreting CD4+ and CD8+ T cells were increased in response to polyclonal activation and tumor antigens. Importantly, Treg frequency was not reduced in the presence of tremelimumab, and expanded Tregs in cancer patients treated with tremelimumab expressed FoxP3 with no IL-2 release, confirming them as bona fide Tregs. Taken together, this data indicates that tremelimumab induces immune responses mainly by direct activation of Teff rather than by affecting Tregs.
The programmed death-1 (PD-1) molecule is mainly expressed on functionally “exhausted” CD8
+
T cells, dampening the host antitumor immune response. We evaluated the ratio between effective and ...regulatory T cells (Tregs) and PD-1 expression as a prognostic factor for operable breast cancer patients. A series of 218 newly diagnosed invasive breast cancer patients who had undergone primary surgery at Ruijin Hospital were identified. The influence of CD8
+
cytotoxic T lymphocytes, FOXP3
+
(Treg cell marker), and PD-1
+
immune cell counts on prognosis was analyzed utilizing immunohistochemistry. Both PD-1
+
immune cells and FOXP3
+
Tregs counts were significantly associated with unfavorable prognostic factors. In bivariate, but not multivariate analysis, high tumor infiltrating PD-1
+
cell counts correlated with significantly shorter patient survival. Our results suggest a prognostic value of the PD-1
+
immune cell population in such breast cancer patients. Targeting the PD-1 pathway may be a feasible approach to treating patients with breast cancer.
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