Tolerogenic dendritic cells (tol-DCs) offer a promising therapeutic potential for autoimmune diseases. Tol-DCs have been reported to inhibit immunogenic responses, yet little is known about the mechanisms controlling their tolerogenic status, as well as associated specific markers. Here we show that the anti-inflammatory TAM receptor tyrosine kinase MERTK, is highly expressed on clinical grade dexamethasone-induced human tol-DCs and mediates their tolerogenic effect. Neutralization of MERTK in allogenic mixed lymphocyte reactions as well as autologous DC-T cell cultures leads to increased T cell proliferation and IFN-g production. Additionally, we identify a previously unrecognized non-cell autonomous regulatory function of MERTK expressed on DCs. Recombinant Mer-Fc protein, used to mimic MERTK on DCs, suppresses nave and antigen-specific memory T cell activation. This mechanism is mediated by the neutralization of the MERTK agonist Protein S (PROS1) expressed by T cells. We find that MERTK and PROS1 are expressed in human T cells upon TCR activation and drive an autocrine pro-proliferative mechanism. Collectively, these results suggest that MERTK on tol-DCs directly inhibits T cell activation through the competition for PROS1 interaction with MERTK in the T cells. Targeting MERTK may provide an interesting approach to effectively increase or suppress tolerance for the purpose of immunotherapy.
MERTK as negative regulator of human T cell activation.
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View SamplesMYCN-high and MYCN-low neuroblastoma cells differ in their responses to Doxorubicin treatment. To explain this difference we compared the global trancriptomes of MYCN-high and MYCN-low cells before, during and after treatment. Overall design: MYCN-high cells without doxycyline and MYCN-low cells with doxycycline were treated with 0.1µg/ml Doxorubicin. Transcriptome was measured for the following time points: in untreated cells, in cells which were treated with Doxorubicin for 72 hours, and in cells collected three, eight and fourteen days after Doxorubin washout. Experiment was performed in biological duplicate.
Cell-Cycle Position of Single MYC-Driven Cancer Cells Dictates Their Susceptibility to a Chemotherapeutic Drug.
Treatment, Subject, Time
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