CCR5-mediated dynamic maintenance of resident memory T cells in the respiratory tract
摘要
Tissue-resident memory T cells (TRM) play a key role in defense against pathogen invading barrier sites and other non-lymphoid tissues. How TRM cells are maintained in various tissues, and how they relate to antigen-experienced memory T cells in lymphoid organs are not fully understood. By barcode-based lineage tracing and single-cell transcriptome analysis, we found a distinct population of CD69+CD103+ virus-specific CD8+ T cells in draining lymph nodes (dLNs) following intranasal influenza infection. Intriguingly, these dLN TRM cells and lung TRM cells shared similar function-neutral barcode contents and transcriptomic features, implicating local circulation between the lung and dLNs in the maintenance of resident memory. Ablation of CXCR3 from CD8+ T cells, which impairs lung TRM generation, severely reduced the abundance of dLN TRM cells, suggesting that dLN TRM cells are connected to lung TRM cells by retrograde migration. Our screen for chemokines and chemokine receptors implicated the CCR5-CCL5 axis in promoting lung-to-dLN migration. Temporary CCR5 blockade by intratracheal administration of Maraviroc, a CCR5 inhibitor, reduced the abundance of dLN TRM cells without affecting lung TRM cells. By intratracheal cell transfer, CCR5-deficient CD8+ T cells were found impaired in lung-to-dLN migration. Finally, dLN TRM cells actively participated in the secondary response and could reconstitute lung TRM cells following influenza infection. Our results support a model in which lung-to-dLN TRM retrograde migration helps maintain the CD8+ memory resident in the respiratory tract and optimizes the local T-cell response to reinfection.