ABSTRACT
Tissue-resident lymphocytes provide organ-adapted protection against invading pathogens. Whereas their biology has been examined in great detail in various infection models, their generation and functionality in response to vaccination has not been comprehensively analyzed in humans. We therefore studied SARS-CoV2 mRNA-vaccine-specific T cells in surgery specimens of kidney, liver, lung, bone marrow and spleen in comparison to paired blood samples from largely virus-naive individuals. As opposed to lymphoid tissues, non-lymphoid organs harbored significantly elevated frequencies of Spike-specific CD4+ T cells compared to paired peripheral blood showing hallmarks of tissue residency and an expanded memory pool. Organ-derived, vaccine-specific T helper (Th) cells were characterized by increased portions of multifunctional cells over those detected in blood. Single-cell RNA sequencing revealed functional rather than organ-specific clusters of Spike-reactive Th cells, indicating similar diversification programs across tissues. T cell receptor (TCR) repertoire analysis indicated that the TCR sequence is a major determinant of transcriptomic state in tissue-resident, vaccine-specific CD4+ T cells. In summary, our data demonstrate that SARS-CoV2 vaccination entails acquisition of tissue memory and residency features in organs distant from the inoculation site, thereby contributing to our understanding of how local tissue protection might be accomplished.
Subject(s)
Bone Marrow DiseasesABSTRACT
SARS-CoV-2 utilizes the ACE2 transmembrane peptidase as essential cellular entry receptor. Several studies have suggested abundant ACE2 expression in the human lung, inferring strong permissiveness to SARS-CoV-2 infection with resultant alveolar damage and lung injury. Against this expectation, we provide evidence that ACE2 expression must be considered scarce, thereby limiting SARS-CoV-2 propagation in the human alveolus. Instead, spectral imaging of ex vivo infected human lungs and COVID-19 autopsy samples depicted that alveolar macrophages were frequently positive for SARS-CoV-2, indicating viral phagocytosis. Single-cell transcriptomics of SARS-CoV-2 infected human lung tissue further revealed strong inflammatory and anti-viral activation responses in macrophages and monocytes, comparable to those induced by MERS-CoV, but with virus-specific gene expression profiles. Collectively, our findings indicate that severe lung injury in COVID-19 likely results from an overwhelming immune activation rather than direct viral damage of the alveolar compartment.Funding: ACH, LES, SH were supported by Berlin University Alliance GC2 Global Health (Corona Virus Pre-Exploration Project). ACH, SH, TW and CD were supported by BMBF (RAPID) and ACH, SH by BMBF (alvBarriereCOVID-19). KH, LB, SL, SH, CD, TW, ACH were funded by BMBF (NFN-COVID 19, Organo-Strat). KH, NS, LES, MW, SH, ADG, CD, TW and ACH were supported by DFG (SFB-TR 84). ACH was supported by BIH, Charite 3R, and Charité-Zeiss MultiDim. KH was supported by BMBF (Camo-COVID-19). MW, NS and SH was supported by BMBF (PROVID). MW and NS was supported by BIH and BMBF (SYMPATH, CAPSyS, NAPKON). BO and DB were funded through the BIH Clinical Single Cell Bioinformatics Pipeline. LB was supported by the BMBF (CoIMMUNE), the DFG (KFO 342) and the IZKF of the Medical Faculty of the WWU. Conflict of Interest: The authors declare no competing interests.Ethical Approval: The study was approved by the ethics committee at the Charité clinic (projects EA2/079/13) and Ärztekammer Westfalen-Lippe and of the Westfälischen Wilhelms-Universität (AZ: 2016-265-f-S). Written informed consent was obtained from all patients.