Highlights d Live, but not killed, Mtb induces type I IFN-mediated metabolic changes in macrophages d IFNb restrains glycolysis and drives mitochondrial stress in activated macrophages d Type I IFN signaling in vivo limits pulmonary macrophage metabolic responses to Mtb d STING signaling is upstream of mitochondrial damage during mycobacterial infection

As innate sentinels in the lung, alveolar macrophages (AMs) play a critical role during Mycobacterium tuberculosis (Mtb) infection as the first cells to encounter bacteria. We previously showed that AMs initially respond to Mtb infection in vivo by mounting a cell-protective, rather than pro-inflammatory response, yet whether the AM response could be modified by environmental factors was unknown. Here, we characterize how previous exposure to mycobacteria, either through subcutaneous vaccination with Mycobacterium bovis (scBCG) or through a contained Mtb infection (coMtb), impacts the initial response by AMs and early innate response in the lung. We find that both scBCG and coMtb accelerate early innate cell activation and recruitment and generate a stronger pro-inflammatory AM response to Mtb in vivo. AMs from scBCG vaccinated mice mount a robust interferon response, while AMs from coMtb mice produce a broader and more diverse inflammatory response. Using single-cell RNA-sequencing, we identify exposure-induced changes to airway-resident cells, with scBCG and coMtb enriching for different AM subpopulations. Ex vivo stimulation assays reveal that AMs from scBCG and coMtb mice switch on an interferon-dependent response, which is absent in AMs from unexposed mice. Overall, our studies reveal significant, durable, and cell-intrinsic modifications to AMs following exposure to mycobacterium, and comparison of scBCG and coMtb models reveals that AMs can be reprogrammed into more than one state. These findings highlight the plasticity of innate responses in the airway and underscore the unexplored potential of targeting AMs through vaccination or host-directed therapy to augment host responses.