Unknown,Transcriptomics,Genomics,Proteomics

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Ionic immune suppression within the tumour microenvironment limits T cell effector function

ABSTRACT: Tumours progress despite being infiltrated by effector T cells. Tumour necrosis is associated with poor survival in a variety of cancers. Here, we report that that necrosis causes release of an intracellular ion, potassium, into the extracellular fluid of human and mouse tumours. Surprisingly, elevated extracellular potassium ([K+]e) was sufficient to profoundly suppress mouse and human T cell anti-tumour function. Elevations in [K+]e acted to acutely impair T cell receptor (TCR) dependent Akt-mTOR phosphorylation and effector function. Potassium mediated suppression of Akt-mTOR signalling and T cell effector function required intact activity of PP2A, a serine/threonine phosphatase. The suppressive effect mediated by elevated [K+]e required a T cell-intrinsic increase in intracellular potassium ([K+]i) and was independent of changes in plasma membrane potential (Vm). Finally, ionic reprogramming of tumour-specific T cells via over-expression of the voltage-gated potassium channel Kv1.3 lowered [K+]i and improved effector functions in vitro and in vivo, with this gain of function being dependent on intact channel function. Consequently, Kv1.3 T cell expression enhanced tumour clearance and the survival of melanoma-bearing mice. These results uncover a previously undescribed ionic checkpoint against T cell function within tumours and identify new strategies for cancer immunotherapy. RNA expression was measured by RNA-Seq on day 5 of cultures, maintained in individual biologial triplicates which were stimulated with immobilized anti-CD3/28 antibodies or kept in complete media (no stim) - with equivalent conditions treated with isotonic media containing elevated potassium.

ORGANISM(S): Mus musculus

SUBMITTER: Suman Kumar Vodnala

PROVIDER: E-GEOD-84996 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Human FOXP3+CD25+CD4+ regulatory T cells (Tregs) play a dominant role in the maintenance of immune homeostasis. Several genes are known to be important for murine Tregs, but for human Tregs the genes and underlying molecular networks controlling the suppressor function still largely remain unclear. We here performed a high-time-resolution dynamic analysis of the transcriptome during the very early phase of human Treg/ CD4+ T-effector cell activation. After constructing a correlation network specific for Tregs based on these dynamic data, we described a strategy to identify key genes by directly analyzing the constructed undirected correlation network. Six out of the top 10 ranked key hubs are known to be important for Treg function or involved in autoimmune diseases. Surprisingly, PLAU (the plasminogen activator urokinase) was among the 4 new key hubs. We here show that PLAU was critical for expression regulation of FOXP3, EOS and several other important Treg genes and the suppressor function of human Tregs. Moreover, we found Plau inhibits murine Treg development and but promotes the suppressive function. Further analysis unveils that PLAU is particularly important for memory Tregs and that PLAU mediates Treg suppressor function via STAT5 and ERK signaling pathways. Our study shows the potential for identifying novel key genes for complex dynamic biological processes using a network strategy based on high-time-resolution data, and highlights a critical role of PLAU in both human and murine Tregs. The construction of a dynamic correlation network of human Tregs provides a useful resource for the understanding of Treg function and human autoimmune diseases. The high-time-resolution time-series transcriptomic data during the very early phase of human Treg/Teff activation could be generally used for further mechanistic analysis of human Treg function. These data could be further used for biological network analysis, dynamic analysis, modeling by experimental researchers, bioinformaticians, computational biologists and systems biologists. We have measured the genome-wide expression of 38,500 genes (probes) by performing a high-time-resolution time-series analysis during the activation process of human regulatory T cells /CD4+ T-effector cells at 19 time points for the first 6h with an equal interval of 20 min. We have also overexpressed the GARP gene in human effector T cells and measured the genome-scale expression for the GARP-overexpressed cells and ThGFP cells at time point 0, 100 and 360min following activation. The stimulation source used in this work is a combination of anti-CD3/-CD28 Dynal beads with IL2 100U/ml.

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Ionic immune suppression within the tumour microenvironment limits T cell effector function

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