Lactobacillus reuteri has been shown to metabolize dietary tryptophan into AhR agonists, such as indole-3-aldehyde, which activate AhR signaling in tumor-infiltrating CD8+ T cells, thereby enhancing IFN-γ production, antitumor immunity, and responsiveness to immune checkpoint blockade (Bender et al., 2023). The gene discussed is CD8A; the disease is neoplasm.