Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of human CD4+ memory T cells reveals they are preferential targets for bystander activation and apoptosis

ABSTRACT: There is much evidence that T cells may be activated via mechanisms which act independently of direct TCR ligation. Despite this, the question of whether such forms of âbystanderâ T cell activation occur during immune responses is hotly debated. To address some outstanding questions, we set up an in vitro system within which to analyse bystander T cell activation in human T cells, in the absence of the possibility for TCR cross-reactivity. In addition, we have investigated the genetic, phenotypic, and functional characteristics of bystander activated T cells. Here, we show that bystander T cell activation is, indeed, observed during a specific immune response, and that it occurs preferentially amongst CD4+ memory T cells. Furthermore, bystander activated T cells display a distinct gene expression profile. The mechanism for bystander T cell activation involves soluble factors, and the outcome is an elevated level of apoptosis. This may provide an explanation for the attrition of T cell memory pools of heterologous specificity during immune responses to pathogens such as viruses. Experiment Overall Design: Three conditions tested with 4 biological repilicates in each: Experiment Overall Design: Resting cells - cells expressing a TCR which does not specifically recognize SEB (VÎ²13.1 T cells) and did not upregulate the activation marker CD25 in response to transwell SEB-stimulated co-culture over a 5 day period. Experiment Overall Design: Bystander activated cells - cells expressing a TCR which does not specifically recognize SEB (VÎ²13.1 T cells), but which did upregulate the activation marker CD25 in response to transwell SEB-stimulated co-culture over a 5 day period. Experiment Overall Design: Directly activated cells - cells expressing a TCR which is known to specifically recognize SEB (VÎ²17 T cells), and which did upregulate the activation marker CD25 in response to direct SEB stimulation over a 5 day period.

ORGANISM(S): Homo sapiens

SUBMITTER: Dilair Baban

PROVIDER: E-GEOD-13738 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Human CD4+ memory T cells are preferential targets for bystander activation and apoptosis.

Bangs Sarah C SC Baban Dilair D Cattan Helen J HJ Li Chris Ka-Fi CK McMichael Andrew J AJ Xu Xiao-Ning XN

Journal of immunology (Baltimore, Md. : 1950) 20090201 4

There is much evidence that T cells may be activated via mechanisms that act independently of direct TCR ligation. Despite this, the question of whether such forms of bystander T cell activation occur during immune responses is hotly debated. To address some outstanding questions, we set up an in vitro system within which to analyze bystander T cell activation in human T cells, in the absence of the possibility for TCR cross-reactivity. In addition, we have investigated the genetic, phenotypic, ...[more]

PMID: 19201849

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Project description:Staphylococcus Enterotoxin B (SEB) is an exotoxin produced by Staphylococcus aureus. It is a public health threat during nosocomial infections. It is also considered as a biological weapon. The Centers for Disease Control and Prevention (CDC) lists SEB as a category B agent of Biodefence. SEB is easily aerosolized and can enter the host through inhalation which could lead to Acute Lung Injury (ALI) and in severe cases, it may result in multiple organ failure, shock and death. It is considered to be a Super-antigen as it activates a large number (30%) of T cells and results in the production of cytokines SEB binds directly to the non polymorphic region of MHC Class II which is expressed on antigen presenting cells and this complex activates T cells expressing a specific variable region of the β chain (Vβ8) of the T cell receptor (TCR). Thus, inhalation of SEB leads to recruitment of immune cells into the lung and secretion of pro-inflammatory cytokines which results in severe damage to the lung by increasing the permeability, and induction of respiratory failure. MicroRNA (miRNAs) is considered one of the mechanisms by which the epigenetic regulation happens. MicroRNA are noncoding small RNAs that have recently been shown to play a role in gene expression. The action of miRNA is dependent on its binding to 3’ Untranslated Region (3’UTR) of mRNA resulting in transcriptional or translational repression. Specifically, the efficacy of gene silencing is determined by the interaction of miRNA seed sequence with the target mRNA. Endocannabinoids are lipid molecules produced endogenously by host cells and bind to cannabinoid receptors, CB1 and CB2. N-Arachidonoylethanolamide or anandamide (AEA) is an endocannabinoid that has been shown to have immunomodulatory effects by our lab and others, although the precise mechanism is not clear. So far through my research, I found that Endocannabinoid is involved in a very unique way in the anti-inflammatory response through upregulation of many anti-inflammatory genes such as FOXP3, ARG1, and IL-10 that targeted by miRNA23a-3p and miRNA 34a-5p as well as the anti-inflammatory phenotype population as it show in the RT-PCR and flow cytometry results.

Project description:The species Staphylococcus (S.) aureus harbors 19 superantigen gene loci, six of which are located in the enterotoxin gene cluster (egc). While these egc superantigens are far more prevalent in clinical S. aureus isolates than non-egc superantigens, they are not a prominent cause of toxic shock. Moreover, neutralizing antibodies against egc superantigens are very rare, even among carriers of egc-positive S. aureus strains. In search of an explanation we have tested two non-exclusive hypotheses: 1) egc and non-egc superantigens have unique intrinsic properties and drive the immune system into different directions; 2) egc and non-egc-superantigens are released by S. aureus under different conditions, which shape the immune response. A comparison of three egc (SEI, SElM and SElO) and three non-egc superantigens (SEB, SElQ, TSST-1) revealed that both induced proliferation of human PBMC with comparable potency and elicited similar Th1/Th2-cytokine signatures. This was supported by gene expression analysis of PBMC stimulated with one representative superantigen from each group (SEI and SEB). They induced very similar transcriptional changes, especially of inflammation-associated gene networks, corresponding to a very strong Th1- and Th17-dominated immune response. In contrast, the regulation of superantigen release differed markedly between both superantigen groups. Egc-encoded proteins were secreted by S. aureus during exponential growth, while non-egc superantigens were released in the stationary phase. We conclude that the distinct biological behavior of egc and non-egc superantigens is not due to their intrinsic properties, which are very similar, but caused by their differential release by S. aureus. Experiment Overall Design: PBMCs from 3 healthy blood donors were purified and treated with Medium (control) and recombinant staphylococcal superantigens SEB and SEI. After 6 hours of treatment, total RNA was extracted and hybridized to Affymetrix GeneChip Arrays.

Project description:Developmental checkpoints in stem/progenitor cells are critical to the determination, commitment and differentiation into distinct lineages. Cancer cells often retain expression of lineage-specific checkpoint proteins, but their potential impact in cancer remains elusive. T lymphocytes mature in the thymus following a highly orchestrated developmental process that entails the successive rearrangements and expression of T-cell receptor (TCR) genes. Low affinity recognition of self-peptide/MHC complexes (self-pMHC) presented by thymic epithelial cells by the TCR of CD4+CD8+ (DP) cortical thymocytes transduces positive selection signals that ultimately shape the developing T cell repertoire. DP thymocytes not receiving these signals die by lack of stimulation whereas those that recognize self-pMHC with high affinity undergo TCR-mediated apoptosis and negative selection. In T-cell acute lymphoblastic leukaemia (T-ALL), leukaemic transformation of maturating thymocytes results from the acquisition of multiple genetic and epigenetic alterations in oncogenes and tumour suppressor genes, that disrupt the normal regulatory circuits and drive clonal expansion of differentiation-arrested lymphoblasts. We show here that TCR triggering by negatively-selecting self-pMHC prevented T-ALL development and leukaemia maintenance in mice. Induction of TCR signalling by high affinity self-pMHC or treatment with monoclonal antibodies to the CD3 signalling chain (anti-CD3) caused massive leukaemic cell death and a gene expression program resembling that of thymocyte negative selection. Importantly, anti-CD3 treatment hampered leukaemogenesis in mice transplanted with either mouse or patient-derived T-ALLs. These data provide a rationale for targeted therapy based on anti-CD3 treatment of T-ALL patients and demonstrate that endogenous developmental checkpoint proteins are amenable to therapeutic intervention in cancer cells. Gene expression data from four culture conditions was performed for the following cells: ALL-SIL-TCRÎ±/Î²-GFP co-cultured on OP9-DL1 for 48 h, ALL-SIL-TCRÎ±/Î²-GFP without co-culture, ALL-SIL cells transduced with TLX shRNA (sh-TLX), and ALL-SIL transduced with sh-control vectors. All conditions are performed in two replicates.

Dataset Information

Transcription profiling of human CD4+ memory T cells reveals they are preferential targets for bystander activation and apoptosis

Publications

Human CD4+ memory T cells are preferential targets for bystander activation and apoptosis.

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