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Molecular mechanisms of granulocyte activation

Applicant Yousefi Shida
Number 127628
Funding scheme Project funding
Research institution Institut für Pharmakologie Medizinische Fakultät Universität Bern
Institution of higher education University of Berne - BE
Main discipline Immunology, Immunopathology
Start/End 01.11.2009 - 31.03.2013
Approved amount 375'000.00
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Keywords (13)

bacteria; basophils; cytokines; eosinophils; epithelial cells; extracellular traps; granulocytes; inflammation; innate immunity; mitochondria; neutrophils; signal transduction; toll-like receptors

Lay Summary (English)

Lead
Lay summary
Eosinophils and neutrophils are specialized white blood cells categorized as granulocytic cell type due to their high content of granules. They build the first line of body defense against invading microorganism as part of innate immunity. Granulocytes are professional phagocytic cells and the standard way for these cells to kill microbes is by eating them. We have shown another alternative mechanism for killing pathogens by these cells. Granulocytes upon stimulation with cytokines or bacterial endotoxins, release fibrous structures composed of mitochondrial DNA and granules to the surrounding tissue in a catapult manner. This extracellular structure is called "extracellular traps". We have shown that these structures physically entrap bacteria and kill them in the extracellular space. Mitochondria are cellular organelles that are constantly under repair and division. The organization, shape and size of these organelles are regulated by frequent fission and fusion events. To understand the mechanism of DNA release by mitochondria, we will explore the fusion and /or fission processes of mitochondria and their effects on mitochondrial DNA release.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Publications

Publication
Extracellular DNA traps in allergic, infectious, and autoimmune diseases.
Simon D, Simon H-U, Yousefi S (2013), Extracellular DNA traps in allergic, infectious, and autoimmune diseases., in Allergy, 68(4), 409-16.
Autophagy is required for self-renewal and differentiation of adult human stem cells.
Salemi Souzan, Yousefi Shida, Constantinescu Mihai A, Fey Martin F, Simon Hans-Uwe (2012), Autophagy is required for self-renewal and differentiation of adult human stem cells., in Cell research, 22(2), 432-5.
Eosinophil extracellular DNA traps: molecular mechanisms and potential roles in disease.
Yousefi Shida, Simon Dagmar, Simon Hans-Uwe (2012), Eosinophil extracellular DNA traps: molecular mechanisms and potential roles in disease., in Current opinion in immunology, 24(6), 736-9.
Extensive accumulation of eosinophil extracellular traps in bullous delayed-pressure urticaria: a pathophysiological link?
Kerstan A, Simon H-U, Yousefi S, Leverkus M (2012), Extensive accumulation of eosinophil extracellular traps in bullous delayed-pressure urticaria: a pathophysiological link?, in The British journal of dermatology, 166(5), 1151-2.
Thymic stromal lymphopoietin stimulates the formation of eosinophil extracellular traps.
Morshed M, Yousefi S, Stöckle C, Simon H-U, Simon D (2012), Thymic stromal lymphopoietin stimulates the formation of eosinophil extracellular traps., in Allergy, 67(9), 1127-37.
Eosinophil and neutrophil extracellular DNA traps in human allergic asthmatic airways.
Dworski Ryszard, Simon Hans-Uwe, Hoskins Aimee, Yousefi Shida (2011), Eosinophil and neutrophil extracellular DNA traps in human allergic asthmatic airways., in The Journal of allergy and clinical immunology, 127(5), 1260-6.
Eosinophil extracellular DNA traps in skin diseases.
Simon Dagmar, Hoesli Susanne, Roth Nina, Staedler Simon, Yousefi Shida, Simon Hans-Uwe (2011), Eosinophil extracellular DNA traps in skin diseases., in The Journal of allergy and clinical immunology, 127(1), 194-9.
Inflammation-associated autophagy-related programmed necrotic death of human neutrophils characterized by organelle fusion events.
Mihalache Cristina C, Yousefi Shida, Conus Sébastien, Villiger Peter M, Schneider E Marion, Simon Hans-Uwe (2011), Inflammation-associated autophagy-related programmed necrotic death of human neutrophils characterized by organelle fusion events., in Journal of immunology (Baltimore, Md. : 1950), 186(11), 6532-42.
Restoration of Akt activity by the bisperoxovanadium compound bpV(pic) attenuates hippocampal apoptosis in experimental neonatal pneumococcal meningitis.
Sury Matthias D, Vorlet-Fawer Lorianne, Agarinis Claudia, Yousefi Shida, Grandgirard Denis, Leib Stephen L, Christen Stephan (2011), Restoration of Akt activity by the bisperoxovanadium compound bpV(pic) attenuates hippocampal apoptosis in experimental neonatal pneumococcal meningitis., in Neurobiology of disease, 41(1), 201-8.
Anti-inflammatory and immunosuppressive effects of the enaminone E121.
El-Hashim Ahmed, Yousefi Shida, Edafiogho Ivan, Raghupathy Raj, Yousif Mariam, Simon Hans-Uwe (2010), Anti-inflammatory and immunosuppressive effects of the enaminone E121., in European journal of pharmacology, 632(1-3), 73-8.
Lysosomal degradation of RhoH protein upon antigen receptor activation in T but not B cells.
Schmidt-Mende Jan, Geering Barbara, Yousefi Shida, Simon Hans-Uwe (2010), Lysosomal degradation of RhoH protein upon antigen receptor activation in T but not B cells., in European journal of immunology, 40(2), 525-9.
RhoH/TTF negatively regulates leukotriene production in neutrophils
Daryadel Arezoo (2009), RhoH/TTF negatively regulates leukotriene production in neutrophils, in Journal of Immunology, 6527.
Viable neutrophils release mitochondrial DNA to form neutrophil extracellular traps
Yousefi Shida (2009), Viable neutrophils release mitochondrial DNA to form neutrophil extracellular traps, in Cell Death and Differentiation, 1438.

Collaboration

Group / person Country
Types of collaboration
Vanterbilt University, Nashville United States of America (North America)
- Publication
Dept. of Dermatology, Inselspital Switzerland (Europe)
- Publication
Dept. of Anatomy, Univ. Bern Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
- Exchange of personnel

Associated projects

Number Title Start Funding scheme
112078 Molecular mechanisms of granulocyte activation 01.04.2006 Project funding
146215 Molecular mechanisms of extracellular DNA trap formation by granulocytes 01.04.2013 Project funding
145003 A new Zeiss LSM 710 laser scanning microscope for the DCR LCI Core Facility 01.12.2012 R'EQUIP
112078 Molecular mechanisms of granulocyte activation 01.04.2006 Project funding

Abstract

Background: The precise features of bacterial, fungal, viral, helminth, and allergic inflammatory responses have not yet been defined. For instance, little information is available regarding the molecular mechanisms that stimulate and control the release of inflammatory mediators from granulocytes as well as how released intracellular components contribute to extracellular killing of pathogens. We recently obtained evidence that activated eosinophils generate extracellular structures containing mitochondrial DNA and granule proteins that bind and kill bacteria.Hypothesis: We hypothesize that other Toll-like receptor (TLR) expressing cells are also able to release mitochondrial DNA and that mitochondrial fusion and fission processes are involved in this process. We further hypothesize that the loss of mitochondrial DNA does not limit the life span of granulocytes, but may modulate some cellular functions. Moreover, the possibility that the released DNA activates TLRs will be tested.Specific aims: We aim investigating neutrophils, basophils, and epithelial cells regarding their capacity to release mitochondrial DNA and to kill bacteria in comparison with eosinophils. We further aim characterizing the molecular mechanism involved in mitochondrial DNA release and want to investigate the consequences for the cell, which released mitochondrial DNA.Methods: Cells are isolated and stimulated with TLR ligands and other inflammatory mediators. We use immunofluorescence and confocal microscopic techniques to characterize the molecular components of the extracellular DNA-containing structures. DNA is analyzed using cell permeable and non-permeable dyes as well as by Southern blotting, PCR, and sequencing techniques. Cell death and apoptosis is analyzed by commonly used and recognized methods. Killing of bacteria is measured by bacterial colony-forming assay. The importance of fission and fusion of mitochondria is analyzed by genetically modified granulocytic cells. Isolated DNA is used to stimulate monocytes and dendritic cells, and pro-inflammatory cytokines are measured by immunoassays.Expected value: A better understanding of the mechanisms of granulocyte activation will lead to new insights into the roles of granulocytes under physiologic and pathologic conditions. Our studies may provide new diagnostic tools in inflammatory diseases as well as molecular target(s) for new anti-inflammatory drugs.
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