Project description:Large biological heterogeneity hallmarks acute myeloid leukemia (AML) and substantially hampers development of novel comprehensive therapies. While all-trans retinoic acid (ATRA) revolutionized therapy of acute promyelocytic leukemia, its impact on other AML subtypes remained largely disappointing. Here we show for the first time that ATRA mediated phosphorylation of the histone demethylase PHF8 induces apoptosis of AML cells of different subtypes via regulation of viral mimicry and subsequent initiation of interferon (IFN) type-I response. Phospho-PHF8 conferred H3K9me2 demethylation at promoter sites of key initiators of cell-intrinsic immune response. Multiomics based analyses revealed activation of cytosolic RNA sensors as key step towards NF-κB driven IFN type-I mediated apoptosis. Epigenetic changes directed by PHF8 also induced a specific proteosome pathway controlling NF-κB activity after its initial activation. Hence, PHF8 orchestrates viral mimicry, triggering IFN type-I response-differentiation-apoptotic network in a broad spectrum of AML when activated by ATRA. Forced phosphorylation of PHF8 via combination treatment with ATRA and simultaneous pharmacological inhibition of PHF8 dephosphorylation significantly impaired growth of human AML. Our findings finally open the gate for successful application of ATRA-based combination therapies in AML.
Project description:TruCulture human whole blood ex vivo stimulation was performed on 17 healthy individuals and 17 post-onset type 1 diabetics, then gene expression was analyzed using Nanostring to characterize stimulated innate immune responses. Ex vivo whole blood stimulation revealed higher induced IFN-1 responses in type 1 diabetes as compared to healthy controls.
Project description:Although mast cells elicit proinflammatory and type I IFN responses upon VSV infection, in response to L.monocytogenes (L.m) or S. Typhimurium (S.t), such cells elicit a transcriptional program devoid of type I IFN response. Balanced induction of proinflamatory and type I interferon (IFN) responses upon activation of Toll like receptors (TLRs) determines the outcome of microbial infections and the pathogenesis of autoimmune and other inflammatory diseases. Mast cells, key components of the innate immune system, are known for their debilitating role in allergy and autoimmune syndromes. However, their potential role in anti-microbial host defenses is increasingly being acknowledged. How mast cells interact with microbes and the nature of responses triggered thereof is not well characterized. Here we show that in response to TLR activation by Gram-positive and negative bacteria or their components like LPS, unlike macrophages, mast cells elicit pro-inflammatory but not type I IFN responses. We demonstrate that in mast cells, the bound bacteria and TLR ligands remain trapped at the cell surface and do not undergo internalization - a prerequisite for type I IFN induction. Such cells could, however, elicit type I IFNs in response to vesicular stomatitis virus (VSV), which accesses the cytosolic RIG-I receptor. Although important for anti-viral immunity, a strong type I IFN response is known to contribute to pathogenesis during bacterial infection. Thus, while endowed with the capacity to elicit type I IFNs in response to viral infection, the fact that mast cells only elicit pro-inflammatory responses upon bacterial infection illustrates that mast cells, key effector cells of the innate immune system, are well adjusted for optimal anti-bacterial and anti-viral responses.
Project description:Host defense requires the specification of CD4+ helper T (Th) cells into distinct fates including Th1 cells that preferentially produce interferon γ(IFN-γ ).IFN-γ , a member of a large family of anti-pathogenic and anti-tumor IFNs, induces T-bet, a lineage defining transcription factor for Th1 cells, which in turn supports IFN-γ production in a feed-forward manner. Herein, we show a cell intrinsic role of T- bet to influence how T cells perceive their secreted product in the environment. In the absence of T-bet, IFN-γ aberrantly induces a type I IFN transcriptomic program. T-bet preferentially represses genes and pathways ordinarily activated by type I IFNs to ensure that its transcriptional response does not evoke an aberrant amplification of type I IFN signaling circuitry otherwise triggered by its own product.