Tumor-Associated Macrophages Derived from Circulating Inflammatory Monocytes Degrade Collagen through Cellular Uptake

Daniel Hargbøl Madsen*, Henrik Jessen Jürgensen, Majken Storm Siersbæk, Dorota Ewa Kuczek, Loretta Grey Cloud, Shihui Liu, Niels Behrendt, Lars Grøntved, Roberto Weigert, Thomas Henrik Bugge

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Physiologic turnover of interstitial collagen is mediated by a sequential pathway in which collagen is fragmented by pericellular collagenases, endocytosed by collagen receptors, and routed to lysosomes for degradation by cathepsins. Here, we use intravital microscopy to investigate if malignant tumors, which are characterized by high rates of extracellular matrix turnover, utilize a similar collagen degradation pathway. Tumors of epithelial, mesenchymal, or neural crest origin all display vigorous endocytic collagen degradation. The cells engaged in this process are identified as tumor-associated macrophage (TAM)-like cells that degrade collagen in a mannose receptor-dependent manner. Accordingly, mannose-receptor-deficient mice display increased intratumoral collagen. Whole-transcriptome profiling uncovers a distinct extracellular matrix-catabolic signature of these collagen-degrading TAMs. Lineage-ablation studies reveal that collagen-degrading TAMs originate from circulating CCR2+ monocytes. This study identifies a function of TAMs in altering the tumor microenvironment through endocytic collagen turnover and establishes macrophages as centrally engaged in tumor-associated collagen degradation. Madsen et al. identify a population of tumor-associated macrophages with a distinct matrix catabolic signature as key effectors of collagen turnover during invasive tumor growth. These matrix-degrading macrophages are largely derived from CCR2+ monocytes reprogrammed by the tumor microenvironment and degrade collagen through mannose receptor-dependent cellular uptake.

Original languageEnglish
JournalCell Reports
Issue number13
Pages (from-to)3662-3671
Publication statusPublished - 26. Dec 2017


  • cancer invasion
  • cathepsins
  • CCR2-derived TAMs
  • collagen endocytosis
  • collagenases
  • endocytic matrix turnover
  • extracellular matrix remodeling
  • M2-polarized macrophages
  • tumor microenvironment
  • tumor-associated macrophages
  • Extracellular Matrix/metabolism
  • Cell Polarity
  • Macrophages/metabolism
  • Receptors, Cell Surface
  • Neoplasms/genetics
  • Endocytosis
  • Proteolysis
  • Inflammation/pathology
  • Collagen/metabolism
  • Mannose-Binding Lectins
  • Lectins, C-Type
  • Mice, Inbred C57BL
  • Rats
  • Monocytes/pathology
  • Transcriptome/genetics
  • Receptors, CCR2/metabolism
  • Animals
  • Cell Movement


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