A CCR2 macrophage endocytic pathway mediates extravascular fibrin clearance in vivo

Research output: Contribution to journalJournal articleResearchpeer-review

Extravascular fibrin deposition accompanies many human diseases and causes chronic inflammation and organ damage, unless removed in a timely manner. Here, we used intravital microscopy to investigate how fibrin is removed from extravascular space. Fibrin placed into the dermis of mice underwent cellular endocytosis and lysosomal targeting, revealing a novel intracellular pathway for extravascular fibrin degradation. A C-C chemokine receptor type 2 (CCR2)-positive macrophage subpopulation constituted the majority of fibrin-uptaking cells. Consequently, cellular fibrin uptake was diminished by elimination of CCR2-expressing cells. The CCR2-positive macrophage subtype was different from collagen-internalizing M2-like macrophages. Cellular fibrin uptake was strictly dependent on plasminogen and plasminogen activator. Surprisingly, however, fibrin endocytosis was unimpeded by the absence of the fibrin(ogen) receptors, αMβ2 and ICAM-1, the myeloid cell integrin-binding site on fibrin or the endocytic collagen receptor, the mannose receptor. The study identifies a novel fibrin endocytic pathway engaged in extravascular fibrin clearance and shows that interstitial fibrin and collagen are cleared by different subsets of macrophages employing distinct molecular pathways.

Original languageEnglish
JournalBlood
Volume127
Issue number9
Pages (from-to)1085-1096
Number of pages12
ISSN0006-4971
DOIs
Publication statusPublished - 2016

    Research areas

  • Animals, Biological Assay, CX3C Chemokine Receptor 1, Cell Proliferation, Endocytosis, Fibrin/metabolism, Fibrinolysin/metabolism, Macrophages/metabolism, Mice, Myeloid Cells/metabolism, Plasminogen/metabolism, Plasminogen Activators/metabolism, Proteolysis, Receptors, CCR2/metabolism, Receptors, Chemokine/metabolism, Receptors, Peptide/metabolism

ID: 201162792