Visualisierung neutrophiler Granulozyten und NETs (Neutrophil Extracellular Traps) mit Expansionsmikroskopie

Visualization of neutrophil granulocytes and NETs (neutrophil extracellular traps) with expansion microscopy

by Louisa Rusch
Doctoral thesis
Date of Examination:2025-03-17
Date of issue:2025-02-14
Advisor:Prof. Dr. Luise Erpenbeck
Referee:Prof. Dr. Luise Erpenbeck
Referee:Prof. Dr. Stefan Jakobs
Referee:Prof. Dr. Dieter Kube
Persistent Address: http://dx.doi.org/10.53846/goediss-11085

 

 

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Abstract

English

Neutrophil granulocytes are short-lived immune cells which play a significant role in the innate immune system. They are the most abundant immune cell type in the blood as well as part of the first line of defence of the body against pathogens. With the discovery of neutrophil extracellular traps (NETs) in 2004, neutrophil granulocytes became a focus in biomedical research, as NETs appear to be involved in a plethora of malignant, cardiovascular, autoimmune and chronic inflammatory diseases. Understanding neutrophil function and morphology could yield novel therapeutic approaches in the above-mentioned illnesses. Moreover, neutrophils possess unique properties that enable them to quickly migrate to the site of inflammation. In particular, nuclear morphology and biomechanics appear to be crucial to many immune defence functions. In spite of the obvious importance of neutrophil cellular morphology and nuclear composition, studying nuclear functions and morphology remains difficult as they require high-resolution imaging up to super-resolution, which is technically challenging and costly. This dissertation shows an efficient method to analyse single-cell organelles such as the nucleus by expansion microscopy, achieving an 4-5 higher resolution. Expansion microscopy is based on linking labelled epitopes to a polymer, which is then expanded in a swelling process. Combining this method with conventional fluorescence microscopy or confocal microscopy yields very specific information about cellular structures at higher resolution. This method was used in this dissertation to image typical neutrophil markers such as myeloperoxidase and to study the distribution of lamins within the nuclear envelope of neutrophils. Furthermore, we characterized neutrophil chromatin composition in unstimulated cells and in neutrophils undergoing NETosis and analysed heterogeneity of microdomains within the nucleus. In conclusion, expansion microscopy is an useful tool to image neutrophils but also other immune cells with ultra-high resolution to reveal novel aspects of their biology.
Keywords: expansion microscopy; neutrophil granulocyte
Schlagwörter: Expansionsmikroskopie; Neutrophile Granulozyten