Chemotherapy-driven intestinal dysbiosis and indole-3-propionic acid rewire myelopoiesis to promote a metastasis-refractory state.

Bersier, Ludivine; Lorenzo-Martin, L Francisco; Chiang, Yi-Hsuan; Durot, Stephan; Czauderna, Aleksander; Yarahmadov, Tural; Wyss Lozano, Tania; Roci, Irena et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

The contribution of chemotherapy-induced tissue injury to individual susceptibility to metastasis remains largely unexplored. We report that chemotherapy indirectly prevents colorectal cancer (CRC) liver metastases by inducing a lasting systemic "chemomemory". Chemotherapy-induced intestinal mucositis alters nutrient availability, promoting the expansion of tryptophan-metabolizing bacteria and production of the microbial metabolite indole-3-propionic acid (IPA). IPA reprograms bone marrow myelopoiesis by redirecting common myeloid progenitor fate toward the macrophage lineage, limiting generation of immunosuppressive Ly6C<sup>high</sup>CCR2<sup>+</sup> monocytes. This shift enhances CD4<sup>+</sup> T cell antitumor function by promoting Th1 differentiation and spatially reorganizing CD8<sup>+</sup> and CD4<sup>+</sup> T cell interactions within the metastatic microenvironment. In a subset of CRC patients, circulating IPA levels increase after chemotherapy and inversely correlate with monocyte abundance, while high monocyte levels were associated with reduced survival. Our findings reveal that chemotherapy-induced intestinal injury normalizes pathological myelopoiesis through a microbiota-derived metabolite and identify IPA as a potential adjuvant to counteract monocyte-driven immunosuppression and metastasis.

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