Integrative single cell and spatial transcriptomic analysis reveal reciprocal microglia-plasma cell crosstalk in the mouse brain during chronicTrypanosoma bruceiinfection

Human African trypanosomiasis, or sleeping sickness, is caused by the protozoan parasiteTrypanosoma bruceiand induces profound reactivity of glial cells and neuroinflammation when the parasites colonise the central nervous system. However, the transcriptional and functional responses of the brain to chronicT. bruceiinfection remain poorly understood. By integrating single cell and spatial transcriptomics of the mouse brain, we identified that glial responses triggered by infection are readily detected in the proximity to the circumventricular organs, including the lateral and 3^rdventricle. This coincides with the spatial localisation of both slender and stumpy forms ofT. brucei. Furthermore,in silicopredictions and functional validations led us to identify a previously unknown crosstalk between homeostaticCx3cr1⁺microglia andCd138⁺plasma cells mediated by IL-10 and B cell activating factor (BAFF) signalling. This study provides important insights and resources to improve understanding of the molecular and cellular responses in the brain during infection with African trypanosomes.