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Zhao H, Wu D, Gyamfi MA, Wang P, Luecht C, Pfefferkorn AM, Ashraf MI, Kamhieh-Milz J, Witowski J, Dragun D, Budde K, Schindler R, Zickler D, Moll G, Catar R. Expanded Hemodialysis ameliorates uremia-induced impairment of vasculoprotective KLF2 and concomitant proinflammatory priming of endothelial cells through an ERK/AP1/cFOS-dependent mechanism. Front Immunol 2023; 14:1209464. [PMID: 37795100 PMCID: PMC10546407 DOI: 10.3389/fimmu.2023.1209464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 08/31/2023] [Indexed: 10/06/2023] Open
Abstract
Aims Expanded hemodialysis (HDx) therapy with improved molecular cut-off dialyzers exerts beneficial effects on lowering uremia-associated chronic systemic microinflammation, a driver of endothelial dysfunction and cardiovascular disease (CVD) in hemodialysis (HD) patients with end-stage renal disease (ESRD). However, studies on the underlying molecular mechanisms are still at an early stage. Here, we identify the (endothelial) transcription factor Krüppel-like factor 2 (KLF2) and its associated molecular signalling pathways as key targets and regulators of uremia-induced endothelial micro-inflammation in the HD/ESRD setting, which is crucial for vascular homeostasis and controlling detrimental vascular inflammation. Methods and results First, we found that human microvascular endothelial cells (HMECs) and other typical endothelial and kidney model cell lines (e.g. HUVECs, HREC, and HEK) exposed to uremic serum from patients treated with two different hemodialysis regimens in the Permeability Enhancement to Reduce Chronic Inflammation II (PERCI-II) crossover clinical trial - comparing High-Flux (HF) and Medium Cut-Off (MCO) membranes - exhibited strongly reduced expression of vasculoprotective KLF2 with HF dialyzers, while dialysis with MCO dialyzers led to the maintenance and restoration of physiological KLF2 levels in HMECs. Mechanistic follow-up revealed that the strong downmodulation of KLF2 in HMECs exposed to uremic serum was mediated by a dominant engagement of detrimental ERK instead of beneficial AKT signalling, with subsequent AP1-/c-FOS binding in the KLF2 promoter region, followed by the detrimental triggering of pleiotropic inflammatory mediators, while the introduction of a KLF2 overexpression plasmid could restore physiological KLF2 levels and downmodulate the detrimental vascular inflammation in a mechanistic rescue approach. Conclusion Uremia downmodulates vasculoprotective KLF2 in endothelium, leading to detrimental vascular inflammation, while MCO dialysis with the novel improved HDx therapy approach can maintain physiological levels of vasculoprotective KLF2.
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Affiliation(s)
- Hongfan Zhao
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Dashan Wu
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Michael Adu Gyamfi
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Pinchao Wang
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Christian Luecht
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | | | | | - Julian Kamhieh-Milz
- Institute of Transfusion Medicine, at Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Janusz Witowski
- Department of Pathophysiology, Poznan University of Medical Sciences, Poznan, Poland
| | - Duska Dragun
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Klemens Budde
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Ralf Schindler
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Daniel Zickler
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Guido Moll
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
- BIH Center for Regenerative Therapies (BCRT) and Berlin-Brandenburg School for Regenerative Therapies (BSRT), at Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Rusan Catar
- Department of Nephrology and Internal Intensive Care Medicine, at Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
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Wang X, Huo R, Liang Z, Xu C, Chen T, Lin J, Li L, Lin W, Pan B, Fu X, Chen S, Collino M. Simvastatin Inhibits NLRP3 Inflammasome Activation and Ameliorates Lung Injury in Hyperoxia-Induced Bronchopulmonary Dysplasia via the KLF2-Mediated Mechanism. Oxidative Medicine and Cellular Longevity 2022; 2022:1-15. [PMID: 35509841 PMCID: PMC9060986 DOI: 10.1155/2022/8336070] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/04/2022] [Indexed: 12/17/2022]
Abstract
Bronchopulmonary dysplasia (BPD) is a chronic lung disease commonly found in premature infants. Excessive inflammation and oxidative stress contribute to BPD occurrence and development. Simvastatin, as an inhibitor of HMG-CoA reductase, has been reported to have antioxidative and anti-inflammatory effects. However, its effect and possible mechanisms in hyperoxia-induced lung injury are rarely reported. In this study, in vivo and in vitro experiments were conducted to investigate whether simvastatin could ameliorate hyperoxia-induced lung injury and explore its potential mechanism. For the in vivo study, simvastatin could improve alveolar development after hyperoxic lung injury and reduce hyperoxic stress and inflammation. The in vitro study revealed that simvastatin can reduce inflammation in A549 cells after high-oxygen exposure. Simvastatin suppressed NLRP3 inflammasome activation and played anti-inflammatory and antioxidant roles by increasing KLF2 (Krüppel-like factor 2) expression. In vitro experiments also revealed that these effects of simvastatin were partially reversed by KLF2 shRNA, indicating that KLF2 was involved in simvastatin effects. In summary, our findings indicate that simvastatin could downregulate NLRP3 inflammasome activation and attenuate lung injury in hyperoxia-induced bronchopulmonary dysplasia via KLF2-mediated mechanism.
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Wittner J, Schuh W. Krüppel-like Factor 2 (KLF2) in Immune Cell Migration. Vaccines (Basel) 2021; 9:1171. [PMID: 34696279 DOI: 10.3390/vaccines9101171] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 09/27/2021] [Accepted: 10/06/2021] [Indexed: 01/30/2023] Open
Abstract
Krüppel-like factor 2 (KLF2), a transcription factor of the krüppel-like family, is a key regulator of activation, differentiation, and migration processes in various cell types. In this review, we focus on the functional relevance of KLF2 in immune cell migration and homing. We summarize the key functions of KLF2 in the regulation of chemokine receptors and adhesion molecules and discuss the relevance of the KLF2-mediated control of immune cell migration in the context of immune responses, infections, and diseases.
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Abstract
Macroautophagy/autophagy is involved in myeloid cellular repair, destruction, and osteoclast differentiation; conversely, KLF2 (kruppel-like factor 2 [lung]) regulates myeloid cell activation and differentiation. To investigate the specific role of KLF2 in autophagy, osteoclastic differentiation was induced in monocytes in presence or absence of the autophagy inhibitor 3-methyladenine (3-MA), KLF2 inducer geranylgeranyl transferase inhibitor (GGTI298), and adenoviral overexpression of KLF2. We found that the number of autophagic cells and multinucleated osteoclasts were significantly decreased in presence of 3-MA, GGTI298, and KLF2 overexpressed cells indicating involvement of KLF2 in these processes. In addition, autophagy-related protein molecules were significantly decreased after induction of KLF2 during the course of osteoclastic differentiation. Furthermore, induction of arthritis in mice reduced the level of Klf2 in monocytes, and enhanced autophagy during osteoclastic differentiation. Mechanistically, knocking down of KLF2 increased the level of Beclin1 (BECN1) expression, and conversely, KLF2 over-expression reduced the level of BECN1 in monocytes. Moreover, 3-MA and GGTI298 both reduced myeloid cell proliferation concomitantly upregulating senescence-related molecules (CDKN1A/p21 and CDKN1B/p27kip1). We further confirmed epigenetic regulation of Becn1 by modulating Klf2; knocking down of Klf2 increased the levels of histone activation marks H3K9 and H4K8 acetylation in the promoter region of Becn1; and overexpression of Klf2 decreased the levels of H4K8 and H3K9 acetylation. In addition, osteoclastic differentiation also increased levels of H3K9 and H4K8 acetylation in the promoter region of Becn1. Together these findings for the first time revealed that Klf2 critically regulates Becn1-mediated autophagy process during osteoclastogenesis.Abbreviations: ACP5/TRAP: acid phosphatase 5, tartrate resistant; Ad-KLF2: adenoviral construct of KLF2; ATG3: autophagy related 3; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG12: autophagy related 12; BECN1: beclin 1, autophagy related; C57BL/6: inbred mouse strain C57 black 6; ChIP: chromatin immunoprecipitation; CSF1/MCSF: colony stimulating factor 1 (macrophage); CTSK: cathepsin K; EV: empty vector; GGTI298: geranylgeranyl transferase inhibitor; H3K9Ac: histone H3 lysine 9 acetylation; H4K8Ac: histone H4 lysine 8 acetylation; K/BxN mice: T cell receptor (TCR) transgene KRN and the MHC class II molecule A(g7) generates K/BxN mice; KLF2: kruppel-like factor 2 (lung); 3MA: 3-methyladenine; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MDC: monodansylcadaverine; NFATc1: nuclear factor of activated T cells 1; NFKB: nuclear factor of kappa light polypeptide gene enhancer in B cells; p21/CDKN1A: cyclin dependent kinase inhibitor 1A; p27kip1/CDKN1B: cyclin-dependent kinase inhibitor 1B; PCR: polymerase chain reaction; PtdIns3K: phosphoinositide 3-kinase; RA: rheumatoid arthritis; siKlf2: small interfering KLF2 ribonucleic acid; NS: non-specific; RAW 264.7: abelson murine leukemia virus transformed macrophage cell line; TNFSF11/RANKL: tumor necrosis factor (ligand) superfamily, member 11; TSS: transcriptional start site; UCSC: University of California, Santa Cruz.
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Affiliation(s)
- Dipranjan Laha
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - Moonmoon Deb
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - Hiranmoy Das
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
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Conti P, Carinci F, Caraffa A, Ronconi G, Lessiani G, Theoharides TC. Link between mast cells and bacteria: Antimicrobial defense, function and regulation by cytokines. Med Hypotheses 2017; 106:10-14. [DOI: 10.1016/j.mehy.2017.06.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 05/04/2017] [Accepted: 06/25/2017] [Indexed: 01/12/2023]
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Nunes de Miranda SM, Wilhelm T, Huber M, Zorn CN. Differential Lyn-dependence of the SHIP1-deficient mast cell phenotype. Cell Commun Signal 2016; 14:12. [PMID: 27206658 PMCID: PMC4874025 DOI: 10.1186/s12964-016-0135-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 05/13/2016] [Indexed: 01/02/2023] Open
Abstract
Background Antigen (Ag)/IgE-mediated mast cell (MC) responses play detrimental roles in allergic diseases. MC activation via the high-affinity receptor for IgE (FcεRI) is controlled by the Src family kinase Lyn. Lyn-deficient (-/-) bone marrow-derived MCs (BMMCs) have been shown by various laboratories to exert stronger activation of the PI3K pathway, degranulation, and production of pro-inflammatory cytokines compared to wild-type (wt) cells. This mimics the phenotype of BMMCs deficient for the SH2-containing inositol-5’-phosphatase 1 (SHIP1). In this line, Lyn has been demonstrated to tyrosine-phosphorylate and activate SHIP1, thereby constituting a negative feedback control of PI3K-mediated signals. However, several groups have also reported on Lyn-/- BMMCs degranulating weaker than wt BMMCs. Results Lyn-/- BMMCs, which show a suppressed degranulation response, were found to exhibit abrogated tyrosine phosphorylation of SHIP1 as well. This indicated that even in the presence of reduced SHIP1 function MC degranulation is dependent on Lyn function. In contrast to the reduced immediate secretory response, pro-inflammatory cytokine production was augmented in Lyn-/- BMMCs. For closer analysis, Lyn/SHIP1-double-deficient (dko) BMMCs were generated. In support of the dominance of Lyn deficiency, dko BMMCs degranulated significantly weaker than SHIP1-/- BMMCs. This coincided with reduced LAT1 and PLC-γ1 phosphorylation as well as Ca2+ mobilization in those cells. Interestingly, activation of the NFκB pathway followed the same pattern as measured by IκBα phosphorylation/degradation as well as induction of NFκB target genes. This suggested that Ag-triggered NFκB activation involves a Ca2+-dependent step. Indeed, IκBα phosphorylation/degradation and NFκB target gene induction were controlled by the Ca2+-dependent phosphatase calcineurin. Conclusions Lyn deficiency is dominant over SHIP1 deficiency in MCs with respect to Ag-triggered degranulation and preceding signaling events. Moreover, the NFκB pathway and respective targets are activated in a Lyn- and Ca2+-dependent manner, reinforcing the importance of Lyn for MC activation. Electronic supplementary material The online version of this article (doi:10.1186/s12964-016-0135-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Susana M Nunes de Miranda
- Institute of Biochemistry and Molecular Immunology, University Clinic, RWTH Aachen University, Pauwelsstraße 30, Aachen, 52074, Germany
| | - Thomas Wilhelm
- Institute of Biochemistry and Molecular Immunology, University Clinic, RWTH Aachen University, Pauwelsstraße 30, Aachen, 52074, Germany
| | - Michael Huber
- Institute of Biochemistry and Molecular Immunology, University Clinic, RWTH Aachen University, Pauwelsstraße 30, Aachen, 52074, Germany.
| | - Carolin N Zorn
- Institute of Biochemistry and Molecular Immunology, University Clinic, RWTH Aachen University, Pauwelsstraße 30, Aachen, 52074, Germany
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Zotz JS, Wölbing F, Lassnig C, Kauffmann M, Schulte U, Kolb A, Whitelaw B, Müller M, Biedermann T, Huber M. CD13/aminopeptidase N is a negative regulator of mast cell activation. FASEB J 2016; 30:2225-35. [PMID: 26936360 DOI: 10.1096/fj.201600278] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 02/11/2016] [Indexed: 12/20/2022]
Abstract
Antigen-induced mast cell (MC) activation via cross-linking of IgE-bound high-affinity receptors for IgE (FcεRI) underlies type I allergy and anaphylactic shock. Comprehensive knowledge of FcεRI regulation is thus required. We have identified a functional interaction between FcεRI and CD13 in murine MCs. Antigen-triggered activation of IgE-loaded FcεRI results in cocapping and cointernalization of CD13 and equivalent internalization rates of up to 40%. Cointernalization is not unspecific, because ligand-driven KIT internalization is not accompanied by CD13 internalization. Moreover, antibody-mediated cross-linking of CD13 causes IL-6 production in an FcεRI-dependent manner. These data are indicative of a functional interaction between FcεRI and CD13 on MCs. To determine the role of this interaction, CD13-deficient bone marrow-derived MCs (BMMCs) were analyzed. Intriguingly, antigen stimulation of CD13-deficient BMMCs results in significantly increased degranulation and proinflammatory cytokine production compared to wild-type cells. Furthermore, in a low-dose model of passive systemic anaphylaxis, antigen-dependent decrease in body temperature, reflecting the anaphylactic reaction, is substantially enhanced by the CD13 inhibitor bestatin (-5.9 ± 0.6°C) and by CD13 deficiency (-8.8 ± 0.6°C) in contrast to controls (-1.2 ± 1.97°C). Importantly, bestatin does not aggravate anaphylaxis in CD13-deficient mice. Thus, we have identified CD13 as a novel negative regulator of MC activation in vitro and in vivo-Zotz, J. S., Wölbing, F., Lassnig, C., Kauffmann, M., Schulte, U., Kolb, A., Whitelaw, B., Müller, M., Biedermann, T., Huber, M. CD13/aminopeptidase N is a negative regulator of mast cell activation.
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Affiliation(s)
- Julia S Zotz
- Institute of Biochemistry and Molecular Immunology, University Hospital, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
| | - Florian Wölbing
- Department of Dermatology, Technical University of Munich, Munich, Germany
| | - Caroline Lassnig
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Marlies Kauffmann
- Institute of Biochemistry and Molecular Immunology, University Hospital, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
| | - Uwe Schulte
- Institute of Physiology II, University of Freiburg, Freiburg, Germany; Centre for Biological Signalling Studies (Bioss), Freiburg, Germany; Logopharm GmbH, March-Buchheim, Germany
| | - Andreas Kolb
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom; and
| | - Bruce Whitelaw
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Mathias Müller
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Tilo Biedermann
- Department of Dermatology, Technical University of Munich, Munich, Germany
| | - Michael Huber
- Institute of Biochemistry and Molecular Immunology, University Hospital, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Aachen, Germany;
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Huber M, Gibbs BF. SHIP1 and the negative control of mast cell/basophil activation by supra-optimal antigen concentrations. Mol Immunol 2015; 63:32-7. [DOI: 10.1016/j.molimm.2014.02.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/19/2014] [Accepted: 02/25/2014] [Indexed: 10/25/2022]
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Abstract
Mast cells (MCs) are tissue-resident sentinels of hematopoietic origin that play a prominent role in allergic diseases. They express the high-affinity receptor for IgE (FcεRI), which when cross-linked by multivalent antigens triggers the release of preformed mediators, generation of arachidonic acid metabolites, and the synthesis of cytokines and chemokines. Stimulation of the FcεRI with increasing antigen concentrations follows a characteristic bell-shaped dose-responses curve. At high antigen concentrations, the so-called supra-optimal conditions, repression of FcεRI-induced responses is facilitated by activation and incorporation of negative signaling regulators. In this context, the SH2-containing inositol-5'-phosphatase, SHIP1, has been demonstrated to be of particular importance. SHIP1 with its catalytic and multiple protein interaction sites provides several layers of control for FcεRI signaling. Regulation of SHIP1 function occurs on various levels, e.g., protein expression, receptor and membrane recruitment, competition for protein-protein interaction sites, and activating modifications enhancing the phosphatase function. Apart from FcεRI-mediated signaling, SHIP1 can be activated by diverse unrelated receptor systems indicating its involvement in the regulation of antigen-dependent cellular responses by autocrine feedback mechanisms or tissue-specific and/or (patho-) physiologically determined factors. Thus, pharmacologic engagement of SHIP1 may represent a beneficial strategy for patients suffering from acute or chronic inflammation or allergies.
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Micheva-Viteva SN, Shou Y, Nowak-Lovato KL, Rector KD, Hong-Geller E. c-KIT signaling is targeted by pathogenic Yersinia to suppress the host immune response. BMC Microbiol 2013; 13:249. [PMID: 24206648 PMCID: PMC3827001 DOI: 10.1186/1471-2180-13-249] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 10/31/2013] [Indexed: 12/27/2022] Open
Abstract
Background The pathogenic Yersinia species exhibit a primarily extracellular lifestyle through manipulation of host signaling pathways that regulate pro-inflammatory gene expression and cytokine release. To identify host genes that are targeted by Yersinia during the infection process, we performed an RNA interference (RNAi) screen based on recovery of host NF-κB-mediated gene activation in response to TNF-α stimulation upon Y. enterocolitica infection. Results We screened shRNAs against 782 genes in the human kinome and 26 heat shock genes, and identified 19 genes that exhibited ≥40% relative increase in NF-κB reporter gene activity. The identified genes function in multiple cellular processes including MAP and ERK signaling pathways, ion channel activity, and regulation of cell growth. Pre-treatment with small molecule inhibitors specific for the screen hits c-KIT and CKII recovered NF-κB gene activation and/or pro-inflammatory TNF-α cytokine release in multiple cell types, in response to either Y. enterocolitica or Y. pestis infection. Conclusions We demonstrate that pathogenic Yersinia exploits c-KIT signaling in a T3SS-dependent manner to downregulate expression of transcription factors EGR1 and RelA/p65, and pro-inflammatory cytokines. This study is the first major functional genomics RNAi screen to elucidate virulence mechanisms of a pathogen that is primarily dependent on extracellular-directed immunomodulation of host signaling pathways for suppression of host immunity.
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Hochdörfer T, Tiedje C, Stumpo DJ, Blackshear PJ, Gaestel M, Huber M. LPS-induced production of TNF-α and IL-6 in mast cells is dependent on p38 but independent of TTP. Cell Signal 2013; 25:1339-47. [PMID: 23499908 DOI: 10.1016/j.cellsig.2013.02.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 02/26/2013] [Indexed: 02/08/2023]
Abstract
The production of the proinflammatory cytokines TNF-α and IL-6 is regulated by various mRNA-binding proteins, influencing stability and translation of the respective transcripts. Research in macrophages has shown the importance of the p38-MK2-tristetraprolin (TTP) axis for regulation of TNF-α mRNA stability and translation. In the current study we examined a possible involvement of p38 and TTP in LPS-induced cytokine production in bone marrow-derived mast cells (BMMCs). Using pharmacological inhibitors we initially found a strong dependence of LPS-induced TNF-α and IL-6 production on p38 activation, whereas activation of the Erk pathway appeared dispensable. LPS treatment also induced p38-dependent expression of the TTP gene. This prompted us to analyze the proinflammatory cytokine response in BMMCs generated from TTP-deficient mice. Unexpectedly, there were no significant differences in cytokine production between TTP-deficient and WT BMMCs in response to LPS. Gene expression and cytokine production of TNF-α and IL-6 as well as stability of the TNF-α transcript were comparable between TTP-deficient and WT BMMCs. In contrast to TTP mRNA expression, TTP protein expression could not be detected in BMMCs. While we successfully precipitated and detected TTP from lysates of LPS-stimulated RAW 264.7 macrophages, this was not accomplished from BMMC lysates. In contrast, we found mRNA and protein expressions of the other TIS11 family members connected to regulation of mRNA stability, BRF1 and BRF2, and detected their interaction with 14-3-3 proteins. These data suggest that control of cytokine mRNA stability and translation in MCs is exerted by proteins different from TTP.
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Affiliation(s)
- Thomas Hochdörfer
- RWTH Aachen University, Medical Faculty, Institute of Biochemistry and Molecular Immunology, Aachen, Germany
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Abstract
Mast cells (MCs) are tissue resident cells of hemopoietic origin and are critically involved in allergic diseases. MCs bind IgE by means of their high-affinity receptor for IgE (FcεRI). The FcεRI belongs to a family of multi-chain immune recognition receptors and is activated by cross-linking in response to multivalent antigens (Ags)/allergens. Activation of the FcεRI results in immediate release of preformed granular substances (e.g. histamine, heparin, and proteases), generation of arachidonic acid metabolites, and production of pro-inflammatory cytokines. The FcεRI shows a remarkable, bell-shaped dose-response behavior with weak induction of effector responses at both low and high (so-called supra-optimal) Ag concentrations. This is significantly different from many other receptors, which reach a plateau phase in response to high ligand concentrations. To explain this unusual dose-response behavior of the FcεRI, scientists in the past have drawn parallels to so-called precipitin curves resulting from titration of Ag against a fixed concentration of antibody (Ab) in solution (a.k.a. Heidelberger curves). Thus, for high, supra-optimal Ag concentrations one could assume that every IgE-bound FcεRI formed a monovalent complex with “its own Ag”, thus resulting in marginal induction of effector functions due to absence of receptor cross-linking. However, this was never proven to be the case. More recently, careful studies of FcεRI activation and signaling events in MCs in response to supra-optimal Ag concentrations have suggested a molecular explanation for the descending part of this bell-shaped curve. It is obvious now that extensive FcεRI/IgE/Ag clusters are formed and inhibitory molecules and signalosomes are engaged in response to supra-optimal cross-linking (amongst them the Src family kinase Lyn and the inositol-5′-phosphatase SHIP1) and they actively down-regulate MC effector responses. Thus, the analysis of MC signaling triggered by supra-optimal crosslinking holds great potential for identifying novel targets for pharmacologic therapeutic intervention to benefit patients with acute and chronic allergic diseases.
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Affiliation(s)
- Michael Huber
- Institute of Biochemistry and Molecular Immunology, University Clinic, RWTH Aachen University, Pauwelsstr, 30, 52074, Aachen, Germany.
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