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A TLR4-dependent fibroblast-monocyte axis in tumor-draining lymph nodes contributes to metastasis in triple-negative breast cancer.

Immunity

Authors: Greta Mattavelli, Moutaz Helal, Ana Cetkovic, Maximilian J Krämer, Saskia-Laureen Herbert, Kilian Mielert, Tanja Schlaiß, Anna Frank, Emily Riemer, Mara John, Josefina Del Pilar, Martinez Vasquez, Laura Kindl, Jonathan J Swietlik, Benedikt O Gansen, Marion Krafft, Emilia Stanojkovska, Hanna Fischer, Ute-Susann Albert, Jonas Bauer, Murilo Delgobo, Arpa Aintablian, Haisam Alattar, Manfred B Lutz, Felix Meissner, Thordur Oskarsson, Leo Rasche, Gustavo Ramos, Andreas Rosenwald, Achim Wöckel, Angela Riedel

Tumor-draining lymph nodes (TDLNs) are sites of anti-tumor immune priming as well as metastases. Here, we examined how the cellular networks within TDLNs are reorganized in triple-negative breast cancer (TNBC). We found that the frequencies of programmed death ligand 1 high (PD-L1) monocytes increased in TDLNs of metastatic TNBC mouse tumors. Fibroblastic reticular cell (FRC) subtypes heightened the expression of the chemokines CCL2 and CCL7, supporting the homing of CCR2 monocytes. These monocytes suppressed T cells in vitro via PD-L1 and inducible nitric oxide synthase (iNOS). Spatial transcriptomics revealed immunosuppressive FRC-monocyte niches in vascularized and T cell areas. Tumor-associated Toll-like receptor (TLR) 4 ligands induced CCL2 and CCL7 expression by FRCs to promote monocyte recruitment. Localized TLR4 inhibition in combination with anti-programmed cell death protein 1 (αPD-1) therapy reduced monocyte homing and boosted T cell function, ultimately attenuating lung metastases. Monocytes accumulate in human TNBC TDLNs, with evidence of a FRC-monocyte axis, and a TLR4 ligand signature is predictive of poor survival outcomes in TNBC patients. Thus, metastatic TNBC can reprogram lymph nodes (LNs) to facilitate PD-L1-mediated immune evasion and metastasis.

Copyright © 2025 The Author(s). Published by Elsevier Inc. All rights reserved.

PMID: 40957419

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