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  1. Article ; Online: Activation of the peroxisome proliferator-activated receptor γ counteracts sepsis-induced T cell cytotoxicity toward alloantigenic target cells.

    von Knethen, Andreas / Sha, Lisa Katharina / Knape, Tilo / Kuchler, Laura / Giegerich, Annika Klara / Schulz, Martin / Hauser, Ingeborg A / Brüne, Bernhard

    Journal of molecular medicine (Berlin, Germany)

    2015  Volume 93, Issue 6, Page(s) 633–644

    Abstract: Unlabelled: Sepsis still emerges as a major cause of patient death in intensive care units. Therefore, new therapeutic approaches are mandatory. Because during sepsis progression cytotoxic T lymphocytes (CTLs) can be activated in an autoimmune fashion ... ...

    Abstract Unlabelled: Sepsis still emerges as a major cause of patient death in intensive care units. Therefore, new therapeutic approaches are mandatory. Because during sepsis progression cytotoxic T lymphocytes (CTLs) can be activated in an autoimmune fashion contributing to multiorgan damage, it remains unclear whether CTLs are activated toward alloantigenic cells. This is important for patients receiving an immunosuppressive therapy to permit organ transplantation and, thus, known to be at high risk for developing sepsis. Therefore, we analyzed whether sepsis activates CTL toward alloantigenic target cells and whether this can be inhibited by PPARγ activation, known to block T helper cell responses. To mimic septic conditions, CTLs were isolated from cecal ligation and puncture-operated mice. CTL cytotoxicity was analyzed following a direct alloantigenic activation regime or following classical ex vivo splenocyte-driven activation in a cytotoxicity assay. With this readout, we found that CTL derived from septic mice enhanced cytotoxicity toward alloantigenic target cells, which was lowered by in vivo and ex vivo PPARγ activation. With CTL derived from T cell-specific PPARγ knockout mice, PPARγ activation was ineffective, pointing to a PPARγ-dependent mechanism. In vivo and ex vivo PPARγ activation reduced Fas and granzyme B expression in activated CTL.
    Key message: In the sepsis CLP mouse model, CTLs are activated toward alloantigenic target cells. Sepsis-mediated alloantigenic CTL activation is blocked in vivo by PPARγ activation. PPARγ deletion or antagonization restored rosiglitazone-dependent inhibition of CTL cytotoxicity. PPARγ inhibits the expression of Fas and granzyme B in CTLs.
    MeSH term(s) Animals ; Cytotoxicity, Immunologic ; Gene Expression Regulation ; Granzymes/genetics ; Humans ; Isoantigens/immunology ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; PPAR gamma/genetics ; PPAR gamma/immunology ; Sepsis/genetics ; Sepsis/immunology ; Sepsis/pathology ; T-Lymphocytes, Cytotoxic/immunology ; T-Lymphocytes, Cytotoxic/metabolism ; T-Lymphocytes, Cytotoxic/pathology ; fas Receptor/genetics
    Chemical Substances Isoantigens ; PPAR gamma ; fas Receptor ; Granzymes (EC 3.4.21.-)
    Language English
    Publishing date 2015-06
    Publishing country Germany
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1223802-8
    ISSN 1432-1440 ; 0946-2716
    ISSN (online) 1432-1440
    ISSN 0946-2716
    DOI 10.1007/s00109-014-1249-8
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Autophagy-dependent PELI3 degradation inhibits proinflammatory IL1B expression.

    Giegerich, Annika Klara / Kuchler, Laura / Sha, Lisa Katharina / Knape, Tilo / Heide, Heinrich / Wittig, Ilka / Behrends, Christian / Brüne, Bernhard / von Knethen, Andreas

    Autophagy

    2014  Volume 10, Issue 11, Page(s) 1937–1952

    Abstract: Lipopolysaccharide (LPS)-induced activation of TLR4 (toll-like receptor 4) is followed by a subsequent overwhelming inflammatory response, a hallmark of the first phase of sepsis. Therefore, counteracting excessive innate immunity by autophagy is ... ...

    Abstract Lipopolysaccharide (LPS)-induced activation of TLR4 (toll-like receptor 4) is followed by a subsequent overwhelming inflammatory response, a hallmark of the first phase of sepsis. Therefore, counteracting excessive innate immunity by autophagy is important to contribute to the termination of inflammation. However, the exact molecular details of this interplay are only poorly understood. Here, we show that PELI3/Pellino3 (pellino E3 ubiquitin protein ligase family member 3), which is an E3 ubiquitin ligase and scaffold protein in TLR4-signaling, is impacted by autophagy in macrophages (MΦ) after LPS stimulation. We noticed an attenuated mRNA expression of proinflammatory Il1b (interleukin 1, β) in Peli3 knockdown murine MΦ in response to LPS treatment. The autophagy adaptor protein SQSTM1/p62 (sequestosome 1) emerged as a potential PELI3 binding partner in TLR4-signaling. siRNA targeting Sqstm1 and Atg7 (autophagy related 7), pharmacological inhibition of autophagy by wortmannin as well as blocking the lysosomal vacuolar-type H(+)-ATPase by bafilomycin A1 augmented PELI3 protein levels, while inhibition of the proteasome had no effect. Consistently, treatment to induce autophagy by MTOR (mechanistic target of rapamycin (serine/threonine kinase)) inhibition or starvation enhanced PELI3 degradation and reduced proinflammatory Il1b expression. PELI3 was found to be ubiquitinated upon LPS stimulation and point mutation of PELI3-lysine residue 316 (Lys316Arg) attenuated Torin2-dependent degradation of PELI3. Immunofluorescence analysis revealed that PELI3 colocalized with the typical autophagy markers MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β) and LAMP2 (lysosomal-associated membrane protein 2). Our observations suggest that autophagy causes PELI3 degradation during TLR4-signaling, thereby impairing the hyperinflammatory phase during sepsis.
    MeSH term(s) Adenosine Triphosphatases/metabolism ; Animals ; Autophagy ; Cell Line ; Cytokines/metabolism ; Immunity, Innate ; Inflammation ; Interleukin-1beta/metabolism ; Lipopolysaccharides/metabolism ; Macrophages/metabolism ; Mice ; Naphthyridines/metabolism ; Point Mutation ; RNA, Messenger/metabolism ; RNA, Small Interfering/metabolism ; Sepsis/metabolism ; Signal Transduction ; Toll-Like Receptor 4/metabolism ; Ubiquitin/metabolism ; Ubiquitin-Protein Ligases/metabolism
    Chemical Substances 9-(6-aminopyridin-3-yl)-1-(3-(trifluoromethyl)phenyl)benzo(h)(1,6)naphthyridin-2(1H)-one ; Cytokines ; IL1B protein, mouse ; Interleukin-1beta ; Lipopolysaccharides ; Naphthyridines ; RNA, Messenger ; RNA, Small Interfering ; Tlr4 protein, mouse ; Toll-Like Receptor 4 ; Ubiquitin ; PELI3 protein, mouse (EC 2.3.2.27) ; Ubiquitin-Protein Ligases (EC 2.3.2.27) ; Adenosine Triphosphatases (EC 3.6.1.-)
    Language English
    Publishing date 2014
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2454135-7
    ISSN 1554-8635 ; 1554-8627
    ISSN (online) 1554-8635
    ISSN 1554-8627
    DOI 10.4161/auto.32178
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: SYNCRIP-dependent Nox2 mRNA destabilization impairs ROS formation in M2-polarized macrophages.

    Kuchler, Laura / Giegerich, Annika Klara / Sha, Lisa Katharina / Knape, Tilo / Wong, Michael Sze Ka / Schröder, Katrin / Brandes, Ralf P / Heide, Heinrich / Wittig, Ilka / Brüne, Bernhard / von Knethen, Andreas

    Antioxidants & redox signaling

    2014  Volume 21, Issue 18, Page(s) 2483–2497

    Abstract: Aims: During sepsis, macrophages are alternatively activated toward an M2-like phenotype on contact with apoptotic cells (ACs) or their secretion products. Simultaneously, NADPH oxidase-dependent reactive oxygen species (ROS) formation is attenuated, ... ...

    Abstract Aims: During sepsis, macrophages are alternatively activated toward an M2-like phenotype on contact with apoptotic cells (ACs) or their secretion products. Simultaneously, NADPH oxidase-dependent reactive oxygen species (ROS) formation is attenuated, thus contributing to immune paralysis. However, the exact mechanism remains elusive. Here, we provide mechanistic insights into diminished mRNA stability of the NADPH oxidase Nox2 on macrophage M2 polarization and therefore reduced ROS formation in sepsis.
    Results: Murine J774A.1 macrophages were stimulated with conditioned medium (CM) of apoptotic T cells, which reduced Nox2 mRNA and protein expression, consequently decreasing ROS production. An mRNA pulldown approach coupled to mass spectrometry analysis identified the RNA-binding protein SYNCRIP attached to the Nox2 mRNA 3' untranslated region (3'UTR). The binding of SYNCRIP to the 3'UTR of Nox2 mRNA is attenuated after treatment with CM of apoptotic T cells, followed by Nox2 mRNA destabilization. In in vivo models of polymicrobial sepsis such as cecal ligation and puncture, SYNCRIP was strongly downregulated, which was associated with a decreased Nox2 expression in peritoneal macrophages.
    Innovation: Downregulation of SYNCRIP in macrophages after contact to material of ACs destabilized Nox2 mRNA and impaired ROS formation, thereby contributing to an M2 phenotype shift of macrophages in sepsis.
    Conclusion: M2 polarization of macrophages in sepsis results in an attenuated SYNCRIP binding to the 3'UTR of Nox2 mRNA, destabilizing Nox2 mRNA abundance and expression. Consequently, ROS formation needed to fight against recurrent infections is impaired. In conclusion, SYNCRIP-regulated Nox2 mRNA degradation mediates the hypoinflammatory phase of sepsis.
    MeSH term(s) Animals ; Apoptosis/genetics ; Gene Expression Regulation ; Heterogeneous-Nuclear Ribonucleoproteins/genetics ; Heterogeneous-Nuclear Ribonucleoproteins/metabolism ; Humans ; Macrophages/metabolism ; Macrophages/pathology ; Membrane Glycoproteins/genetics ; Membrane Glycoproteins/metabolism ; Mice ; NADPH Oxidase 2 ; NADPH Oxidases/genetics ; NADPH Oxidases/metabolism ; RNA Stability ; RNA, Messenger/genetics ; Reactive Oxygen Species/metabolism ; Sepsis/genetics ; Sepsis/metabolism ; Sepsis/pathology ; Signal Transduction
    Chemical Substances Heterogeneous-Nuclear Ribonucleoproteins ; Membrane Glycoproteins ; RNA, Messenger ; Reactive Oxygen Species ; Syncrip protein, mouse ; Cybb protein, mouse (EC 1.6.3.-) ; NADPH Oxidase 2 (EC 1.6.3.-) ; NADPH Oxidases (EC 1.6.3.-)
    Language English
    Publishing date 2014-12-20
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1483836-9
    ISSN 1557-7716 ; 1523-0864
    ISSN (online) 1557-7716
    ISSN 1523-0864
    DOI 10.1089/ars.2013.5760
    Database MEDical Literature Analysis and Retrieval System OnLINE

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