While most novel tuberculosis (TB) vaccines are designed for delivery via the muscle or skin for enhanced protection in the lung, it has remained poorly understood whether systemic vaccine-induced memory T cells can readily home to the lung mucosa prior to and shortly after pathogen exposure. We have investigated this issue by using a model of parenteral TB immunization and intravascular immunostaining. We find that systemically induced memory T cells are restricted to the blood vessels in the lung, unable to populate either the lung parenchymal tissue or the airway under homeostatic conditions. We further find that after pulmonary TB infection, it still takes many days before such T cells can enter the lung parenchymal tissue and airway. We have identified the acquisition of CXCR3 expression by circulating T cells to be critical for their entry to these lung mucosal compartments. Our findings offer new insights into mucosal T cell biology and have important implications in vaccine strategies against pulmonary TB and other intracellular infections in the lung.
CXCR3 Signaling Is Required for Restricted Homing of Parenteral Tuberculosis Vaccine-Induced T Cells to Both the Lung Parenchyma and Airway.
Sex, Specimen part, Time
View SamplesInnate immune memory is a new important area of research. However, innate immune memory at the major mucosal sites remains poorly understood. Here we show that respiratory viral infection induces long-lasting memory alveolar macrophages (AM). Memory AM are programed to express high MHC II, carry a defense-ready gene signature, and produce, upon re-stimulation, neutrophil chemokines. Using a multitude of approaches, we reveal that the priming, but not maintenance, of memory AM requires the help from effector CD8 T cells. T cells jump-start this process in AM via IFN- production. We further find that formation/maintenance of memory AM are independent of monocytes or bone marrow progenitors. Finally, we demonstrate that memory AM are poised for robust trained immunity against bacterial infection in the lung via rapid induction of chemokines and neutrophilia. Our study thus establishes a new paradigm of immunological memory formation whereby adaptive T-lymphocytes render innate memory of mucosal-associated macrophages.
Induction of Autonomous Memory Alveolar Macrophages Requires T Cell Help and Is Critical to Trained Immunity.
Sex
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