Heterogeneity of tissue macrophages in adult Drosophila melanogaster- Characterization and identification of macrophage subsets in health and disease
Cell Biology
Final Report Abstract
Tissue resident macrophages (TRM) are innate immune cells found throughout all organs and serving essential functions in immune defence as well as maintenance of tissue functions. Each TRM population is therefore highly adjusted to the specific needs of its host organ. TRM equivalents are conserved across species and can be even found in invertebrates, such as the fruit fly (Drosophila melanogaster) Here, hemocytes, the Drosophila blood-like cells can be divided in three major cell types, with plasmatocytes representing the macrophage-like cells of the fly. Interestingly, plasmatocytes exhibit many conserved functions compared to their vertebrate counterparts and share a stratified hematopoietic origin. Even though, plasmatocytes are widely studied in Drosophila, less is known about their tissue specification and the contribution of their ontogeny to their functions in development, health and disease. Within this project, we aimed to explore plasmatocyte heterogeneity in Drosophila in terms of ontogeny, transcription profiles and function in health and disease. While undertaking this project, we first spend a lot of time in the establishment of a reliable pipeline to perform single cell transcriptomic profiling in adult Drosophila to analyse heterogeneity of plasmatocytes but also to explore the interaction of plasmatocytes and effects in other tissues during disease settings. Data obtained in this project suggested that loss of hemocytes in adult Drosophila renders these flies more susceptible to oxidative stress modelled by oral Paraquat treatment. Therefore, we decided to focus during the funding period on deciphering the heterogeneity and function of plasmatocytes during oxidative stress. Our data revealed an essential role of hemocytes to control susceptibility to oxidative stress, where hemocytes orchestrate systemic oxidative stress response by defined cellular states identified by single nuclei RNA-sequencing (snRNA-seq). Plasmatocytes segregate in oxidative stress responder subclusters, characterized by immune activation and cellular stress response, and potential bystander subsets associated with metabolic gene regulations. Mechanistically, we found that a DNA damage controlled signalling cascade regulated proinflammatory cytokine release, such as unpaired-3, and therefore controls the susceptibility of the fly to oxidative stress. Hence, our data point to a key role of plasmatocytes in balancing systemic cytokine levels and stress response upon oxidative stress. Collectively we provide new insights on the heterogeneity of plasmatocytes in oxidative stress and steady state and subsequently into the role of macrophages in orchestrating systemic stress responses across tissues to balance tissue wasting and energy mobilization, which can have further implications in chronic diseases such as cancer or neurodegenerative diseases.
Publications
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Detection of G-Quadruplex DNA Structures in Macrophages. Methods in Molecular Biology, 453-462. Springer US.
Kastl, Melanie; Hersperger, Fabian; Kierdorf, Katrin & Paeschke, Katrin
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Hemocyte Nuclei Isolation from Adult Drosophila melanogaster for snRNA-seq. Methods in Molecular Biology, 71-79. Springer US.
Hersperger, Fabian; Kastl, Melanie; Paeschke, Katrin & Kierdorf, Katrin
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DNA damage signaling in Drosophila macrophages modulates systemic cytokine levels in response to oxidative stress. eLife, 12.
Hersperger, Fabian; Meyring, Tim; Weber, Pia; Chhatbar, Chintan; Monaco, Gianni; Dionne, Marc S.; Paeschke, Katrin; Prinz, Marco; Groß, Olaf; Classen, Anne-Kathrin & Kierdorf, Katrin
