piwik-script

Intern
Institut für Hygiene und Mikrobiologie

Cellular Microbiology (Schubert-Unkmeir lab)


Neisseria meningitidis (Nm, meningococcus) is an obligate commensal in humans, colonizing the nasopharyngeal mucosa usually without affecting the host. After the onset of colonization, Nm strains occasionally penetrate the mucosal membrane and enter the bloodstream to cause severe septicemia. Following bacteremia, Nm may bind and subsequently cross the meningeal blood-cerebrospinal fluid barrier (BCSFB) to enter the subarachnoid space and cause meningitis.

BCSFB penetration and development of novel multicellular in vitro models

The group’s major research focus lies on molecular interactions of Nm with microvascular brain endothelial cells (BECs) and mechanisms of BCSFB penetration. For this purpose, we use a variety of tissue culture techniques and cellular models, as well as a wide spectrum of innovative molecular, biochemical methods and imaging techniques. One current research topic covers the development of human, multicellular models of the BCSFB, which includes stem cell-derived BECs and leptomeningeal cells.

Sphingolipids and meningococcal meningitis

Sphingolipid-enriched membrane microdomains contribute to a variety of cellular processes, including signal transduction and vesicle trafficking, and can be exploited by pathogens such as Nm for host cell entry. Current work in this area is focused on the role of the downstream metabolite sphingosine 1-phosphate (S1P) and S1P-producing Sphingosine kinases 1 and 2 (Sphk1/2).

Nasopharyngeal colonization and transmigration

Meningococcal colonization of the nasopharynx is a dynamic process. Nm must mediate complex interactions with host epithelium, and persist in the presence of normal microflora and host mucosal defenses. We are currently developing an air-liquid Interface (ALI) human epithelial model to study the impact of Nm on the architecture and physiology of polarized epithelium and aim to characterize the process of meningococcal penetration of this barrier.

‘Click-AT-CLEM’ for imaging and tracking azido-functionalized sphingolipids in bacteria


In a collaboration project between researchers from IHM (AG Schubert-Unkmeir) together with the groups of Prof. J. Seibel, Prof. M. Sauer, Prof. C. Stigloher and Prof. B. Kleuser, introduce ‘click-AT-CLEM’, a labeling technique for correlated light and electron microscopy (CLEM) based on the super-resolution array tomography (srAT) approach and bio-orthogonal click chemistry for imaging of azido-tagged sphingolipids in Neisseria meningitidis at subcellular level. Click-AT-CLEM imaging and mass spectrometry clearly revealed efficient incorporation of azido-tagged sphingolipids into the outer membrane of the Gram-negative bacterium as an underlying cause of their antimicrobial activity.

 

Reference: Peters, S., Kaiser, L., Fink, J. Schumacher, F., Perschin, V., Schlegel, J. , Sauer, M., Stigloher, C., Kleuser, B., Seibel, J. and Schubert-Unkmeir, A. Click-correlative light and electron microscopy (click-AT-CLEM) for imaging and tracking azido-functionalized sphingolipids in bacteria. Sci Rep 11, 4300 (2021). https://doi.org/10.1038/s41598-021-83813-w

Funding FOR2123/DFG and GRK2581/DFG

February 18th, 2021 Congratulations Simon - great performance!

Simon Peters defends his PhD thesis on the „The impact of sphingolipids on Neisseria meningitidis and their role in meningococcal pathogenicity”

 

September 2020: Glückwünsche an Michael - Promotionspreis der Unterfränkischen Gedenkjahrstiftung für Wissenschaft

Auch in diesem Jahr haben die Unterfränkische Gedenkjahrstiftung für Wissenschaft und die Universität Würzburg zum Stiftungsfest Promotionspreise vergeben. Das obligatorische Gruppenfoto kam wegen Corona allerdings nicht zustande. (Bild: iStock.com/skodonnell)

Mit 500 Euro sind die gemeinsamen Promotionspreise der Unterfränkischen Gedenkjahrstiftung für Wissenschaft und der Universität Würzburg dotiert. Sie werden jedes Jahr für herausragende Dissertationen verliehen. Voraussetzung: Die Arbeiten müssen sich mit Unterfranken befassen und/oder von Personen geschrieben sein, die in der Region aufgewachsen sind oder seit längerer Zeit hier leben.

Eigentlich werden diese Preise traditionellerweise im Rahmen des Stiftungsfests der Universität Würzburg von Unterfrankens Regierungspräsident Eugen Ehmann, in seiner Funktion als Vorsitzender des Vorstands der Unterfränkischen Gedenkjahrstiftung für Wissenschaft, und dem Präsidenten der JMU, Alfred Forchel, verliehen. Aufgrund der Einschränkungen zum Infektionsschutz konnte eine persönliche Übergabe in diesem Jahr jedoch nicht erfolgen. Immerhin erhielten die Ausgezeichneten ihre Urkunde per Post.

Reference: Disease and Carrier Isolates of Neisseria meningitidis Cause G1 Cell Cycle Arrest in Human Epithelial Cells Michael von Papen, Wilhelm F. Oosthuysen, Jérôme Becam, Heike Claus, Alexandra Schubert-Unkmeir

July 2020: Congrats – Leo and Brandon’s JoVE paper is out


As Neisseria meningitidis is a human-specific pathogen, the lack of robust in vivo model systems makes study of the host-pathogen interactions between Nm and BECs challenging and establishes a need for a human based model that mimics native BECs. Recent advances in human stem-cell technologies have developed methods for deriving brain-like endothelial cells from induced pluripotent stem-cells (iPSCs) that better phenocopy BECs when compared to other in vitro human models. The use of iPSC-derived BECs (iPSC-BECs) to model Nm-BEC interaction has the benefit of using human cells that possess BEC barrier properties, and can be used to examine barrier destruction, innate immune activation, and bacterial interaction. Here we demonstrate how to derive iPSC-BECs from iPSCs in addition to bacterial preparation, infection, and sample collection for analysis.

Reference: Endres, L. M., Schubert-Unkmeir, A., Kim, B. J. Neisseria meningitidis Infection of Induced Pluripotent Stem-Cell Derived Brain Endothelial Cells. J. Vis. Exp. (161), e61400, doi:10.3791/61400 (2020).

Leo Endres

PhD student

Tel.: +49 931 31-46944
Mail:

Ingo Fohmann

PhD student

Tel.: +49 931 31-46944
Mail:

Hannah Franke

Technical assistant

Tel.: +49 931 31-46909
Mail:

Dr. rer. nat. Simon Peters

Postdoc

Tel.: +49 931 31-46944
Mail:

Prof. Dr. med. Alexandra Schubert-Unkmeir

Group leader

Tel.: +49 931 31-46721
Mail:

Peters S, Fohmann I, Rudel T and Schubert-Unkmeir A, A comprehensive review on the interplay between Neisseria spp. and host sphingolipid metabolites, cells. Cells. 2021 Nov 17;10(11):3201. doi: 10.3390/cells10113201.

Krone M, Gütling J, Wagener J, Lâm TT, Schoen C, Vogel U, Stich A, Wedekink F, Wischhusen J, Kerkau T, Beyersdorf N, Klingler S, Backes S, Dölken L, Gasteiger G, Kurzai O, Schubert-Unkmeir A (2021) Performance of Three SARS-CoV-2 Immunoassays, Three Rapid Lateral Flow Tests, and a Novel Bead-Based Affinity Surrogate Test for the Detection of SARS-CoV-2 Antibodies in Human Serum. J Clin Microbiol 59(8):e0031921.

Peters S, Kaiser L, Fink J, Schumacher F, Perschin V, Schlegel J, Sauer M, Stigloher C, Kleuser B, Seibel J, Schubert-Unkmeir A. (2021) Click-correlative light and electron microscopy (click-AT-CLEM) for imaging and tracking azido-functionalized sphingolipids in bacteria.  Sci Rep. 2021 Feb 22;11(1):4300. doi: 10.1038/s41598-021-83813-w. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7900124/

Schlegel J, Peters S, Doose S, Schubert-Unkmeir A, Sauer M (2019) Super-resolution microscopy reveals local accumulation of plasma membrane gangliosides at Neisseria meningitidis invasion sites. Front Cell Dev Biol. 2019 Sept 7, 194. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6753371/

Martins Gomes SF, Westermann AJ, Sauerwein T, Hertlein T, Förstner KU, Ohlsen K, Metzger M, Shusta EV, Kim BJ, Appelt-Menzel A, Schubert-Unkmeir A. Induced Pluripotent Stem Cell-Derived Brain Endothelial Cells as a Cellular Model to Study Neisseria meningitidis Infection. Front Microbiol. 2019 May 29;10:1181 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6548865/

Peters S, Schlegel J, Becam J, Avota E, Sauer M, Schubert-Unkmeir A. Neisseria meningitidis type IV pili trigger Ca2+-dependent lysosomal trafficking of the acid sphingomyelinase to enhance surface ceramide levels. Infect Immun. 2019 Jun 3. pii: IAI.00410-19. doi: 10.1128/IAI.00410-19.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6652772/

Herrmann JB, Muenstermann M, Strobel L, Schubert-Unkmeir A, Woodruff TM, Gray-Owen SD, Klos A, Johswich KO. Complement C5a Receptor 1 Exacerbates the Pathophysiology of N. meningitidis Sepsis and Is a Potential Target for Disease Treatment. MBio. 2018 Jan 23;9(1). pii: e01755-17. doi: 10.1128/mBio.01755-17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5784250/

Becam J, Walter T, Burgert A, Schlegel J, Sauer M, Seibel J, Schubert-Unkmeir A. Antibacterial activity of ceramide and ceramide analogs against pathogenic Neisseria. Sci Rep. 2017 Dec 15;7(1):17627. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5732201/

Burgert A, Schlegel J, Bécam J, Doose S, Bieberich E, Schubert-Unkmeir A, Sauer M. Characterization of Plasma Membrane Ceramides by Super-Resolution Microscopy. Angew Chem Int Ed Engl. 2017 Apr 5. doi: 10.1002/anie.201700570. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5549273/

von Papen M, Oosthuysen WF, Becam J, Claus H, Schubert-Unkmeir A. Disease and Carrier Isolates of Neisseria meningitidis Cause G1 Cell Cycle Arrest in Human Epithelial Cells. Infect Immun. 2016 Sep 19;84(10):2758-70. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5038092/

Oosthuysen WF, Mueller T, Dittrich MT, Schubert-Unkmeir A. Neisseria meningitidis causes cell cycle arrest of human brain microvascular endothelial cells at S phase via p21 and cyclin G2. Cell Microbiol. 2016 Jan;18(1):46-65. https://pubmed.ncbi.nlm.nih.gov/26149128/

Simonis, A., Hebling, S., Gulbins, E., Schneider-Schaulies, S. and Schubert-Unkmeir, A. Differential activation of acid sphingomyelinase and ceramide release determines invasiveness of Neisseria meningitidis into brain endothelial cells. PLoS Pathog. 2014 Jun 12;10(6):e1004160.https://pubmed.ncbi.nlm.nih.gov/24945304/

Further publications of the research group on Pubmed