Masterclass Sander van Kasteren

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T-cell activation is one of the key events in the adaptive immune response. In this process, naïve T-cells turn from boring, featureless, cells into the most potent and selective executioners and orchestrators of the immune response. Their correct activation is therefore essential to fight all kinds of pathogens and cancer types. Their mis-activation on the other hand can be very dangerous and lead to immune system deactivation, or worse: auto-immune disease.

Our molecular understanding of the processes that govern T-cell activation (and their deactivation, and reactivation in cancer) are still somewhat limited. The van Kasteren-group has long focussed on the development of chemical techniques to shed light on this pathway in new ways. This includes the combination of click chemistry and correlative light-electron microscopy to study the biology of antigen presenting cells[1, 2], to the use of photo-cleavage and unclick chemistry to study timing and location of immune reactions[3-5].

In this masterclass, I will focus on two recent new methods from the van Kasteren-lab. The first is a new method to measure the kinetics of binding of ligands to immune receptors on the surface of the living cell at single molecule resolution. We have shown that binding of carbohydrates to their receptors are very heterogeneously distributed over the surface of immune cells. And that the immune activation biology of the receptor correlates with very specific binding parameters [6].

The second project I will talk about is a new set of tools to study the uptake of nutrient by immune cells. T-cells eat enormous amounts of fuel during their activation process, but unbiased quantification of this eating, and the functional effect at the single cell level of eating a lot or a little, was not possible. We developed a method using different types of click chemistry that allows us to quantify the uptake of glutamine, fatty acid, LDL-particles and glucose at the single cell level [7, 8], and can integrate these data into full spectrum flow cytometry, single cell sequencing, proteomics and OCR/ECAR real time metabolism experiments. In addition, for certain nutrients we can the uptake processes in real time[9]. I will also touch upon the application of this technology to the recent discovery that nutrients are shuttled between macrophages and glioblastoma cells.[10]

Biography
Sander van Kasteren is a Professor of Molecular Immunology within the Institute of Chemical Immunology and the Leiden Institute of Chemistry at Leiden University. He obtained his DPhil in organic chemistry from the University of Oxford with Prof. Benjamin G. Davis. After which he worked as both a Henry Wellcome Fellow and a Veni Fellow in the laboratories of Prof. Colin Watts (University of Dundee) and Prof. Huib Ovaa (Netherlands Cancer Institute).Upon starting his own group at Leiden in 2012, he combined his backgrounds in synthetic chemistry and immunology to develop new approaches to study the immune system, for this he has been awarded with an ERC Starting, Consolidator, and PoC-grant, and an Early Career Research Award of the British Biochemical Society. He is the current secretary of the Institute of Chemical Immunology and serves as editorial board member of RSC Chemical Biology.

References:
1. Bakkum, T., et al., Bioorthogonal Correlative Light-Electron Microscopy of Mycobacterium tuberculosis in Macrophages Reveals the Effect of Antituberculosis Drugs on Subcellular Bacterial Distribution. ACS Central Science, 2020. 6(11): p. 1997-2007.
2. van Leeuwen, T., et al., Bioorthogonal protein labelling enables the study of antigen processing of citrullinated and carbamylated auto-antigens. RSC Chemical Biology, 2021. 2(3): p. 855-862.
3. van der Leun, A.M., et al., Single-cell analysis of regions of interest (SCARI) using a photosensitive tag. Nature Chemical Biology, 2021. 17(11): p. 1139-1147.
4. van de Graaff, M.J., et al., Conditionally Controlling Human TLR2 Activity via Trans-Cyclooctene Caged Ligands. Bioconjugate Chemistry, 2020. 31(6): p. 1685-1692.
5. Maurits, E., et al., Immunoproteasome inhibitor–doxorubicin conjugates target multiple myeloma cells and release doxorubicin upon low-dose photon irradiation. Journal of the American Chemical Society, 2020. 142(16): p. 7250-7253.
6. Riera, R., et al., Single-molecule imaging of glycan-lectin interactions on cells with Glyco-PAINT. Nature Chemical Biology, 2021. 17(12): p. 1281-1288.
7. Pelgrom, L.R., et al., QUAS-R: An SLC1A5-mediated glutamine uptake assay with single-cell resolution reveals metabolic heterogeneity with immune populations. Cell Reports, 2023. 42(8).
8. Bertheussen, K., et al., Live-Cell Imaging of Sterculic Acid—a Naturally Occurring 1,2-Cyclopropene Fatty Acid—by Bioorthogonal Reaction with Turn-On Tetrazine-Fluorophore Conjugates. Angewandte Chemie International Edition, 2022. 61(38): p. e202207640.
9. Wang Y., Torres-Garcia, D., et al. A Bioorthogonal Dual Fluorogenic Probe for the Live-Cell Monitoring of Nutrient Uptake by Mammalian Cells. Angewandte Chemie International Edition 2024, 63 (32), p. e202401733.
10. Kloosterman, D. J. et al. Macrophage-mediated myelin recycling fuels brain cancer malignancy. Cell 2024, 187, p5336-5356