Lung resident memory CD8+ T cells derived from central memory T cells enhance tumor lung metastasis protection 2605

Abstract Description Memory T cells play a key role in immune protection against cancer. Vaccine-induced tissue-resident memory T (TRM) cells in the lung have been shown to protect against lung metastasis. Identifying the source of lung TRM cells can help to improve strategies, preventing tumor metastasis. Here, we found that a prime-boost vaccination approach using intramuscular DNA vaccine priming, followed by intranasal live-attenuated influenza vectored vaccine (LAIV) boosting induced higher frequencies of lung CD8+ TRM cells compared with other vaccination regimens. Vaccine-induced lung CD8+ TRM cells, but not circulating memory T cells, conferred significant protection against metastatic melanoma and mesothelioma. Central memory T (TCM) cells induced by the DNA vaccination were major precursors of lung TRM cells established after the intranasal LAIV boost. Single-cell RNA sequencing analysis indicated that transcri! ptional reprogramming of TCM cells for differentiation into TRM cells in the lungs started as early as day 2 post the LAIV boost. Intranasal LAIV altered the mucosal microenvironment to recruit TCM cells via CXCR3- dependent chemotaxis and induced CD8+ TRM-associated transcriptional programs. These results identified TCM cells as the source of vaccine-induced CD8+ TRM cells that protect against lung metastasis. Funding Sources Supported by RGC TRS (T11-706/18-N, T12-703/23-N, and T11-702/24-N to Z. Chen) and Collaborative Research Fund (C7156-20G), RGC GRF (17117422), Health@InnoHK (Center for Virology, Vaccinology and Therapeutics) Topic Categories Mucosal and Regional Immunology (MUC)