Bacterial immunotherapy leveraging IL-10R hysteresis for both phagocytosis evasion and tumor immunity revitalization [ATACseq]

Bacterial immunotherapy holds promising cancer-fighting potential. However, unlocking its power requires a mechanistic understanding of how bacteria both evade antimicrobial immune defenses and stimulate antitumor immune responses within the tumor microenvironment (TME). Here, by harnessing an engineered Salmonella enterica strain with this dual proficiency, we unveiled a singular mechanism underlying. Specifically, the hysteretic nonlinearity of interleukin-10 receptor (IL-10R) expression drives tumor-infiltrated immune cells into a tumor-specific IL-10Rhi state. Bacteria leverage this to enhance tumor-associated macrophages producing IL-10, evade phagocytosis by tumor-associated neutrophils, and coincidently expand and stimulate the preexisting exhausted tumor-resident CD8+ T cells. This effective combination eliminated tumors, prevented recurrence, and inhibited metastasis across multiple tumor types. Analysis of human samples suggested that IL-10Rhi state might be a ubiquitous trait across human tumor types. Our study unveils the unsolved mechanism behind bacterial immunotherapy's dual challenge in solid tumors and provides a framework for intratumor immunomodulation. Overall design: Workflow for isolating and treating primary CD8 T cells from mouse spleens. Briefly, isolated CD8+ T cells were stimulated with anti-mouse CD3e and CD28 antibodies for 12 h, followed by antibody removal and washing. Cells were divided into four groups: Pre-exposure (direct sample collection), Initial exposure (stimulated with 10 ng/ml IL-10 for 6 h), Rest (stimulated with 10 ng/ml IL-10 for 6 h, washed, and cultured for 48 h in 0.5 ng/ml IL-10 with medium changes every 12 h), and Subsequent exposure (same as Rest, with an additional 6-h stimulation with 10 ng/ml IL-10)