Fibronectin-bound TNF-alpha stimulates monocyte matrix metalloproteinase-9 expression and regulates chemotaxis

J Leukoc Biol. 2000 Nov;68(5):737-47.


Tumor necrosis factor alpha (TNF-alpha) is a proinflammatory cytokine implicated in the stimulation of matrix metalloproteinase (MMP) production by several cell types. Our previous studies demonstrated that TNF-alpha avidly binds fibronectin (FN) and laminin, major adhesive glycoproteins of extracellular matrix (ECM) and basement membranes. These findings suggested that TNF-alpha complexing to insoluble ECM components may serve to concentrate its activities to distinct inflamed sites. Herein, we explored the bioactivity and possible function of ECM-bound TNF-alpha by examining its effects on MMP-9 secretion by monocytes. Immunofluorescent staining indicated that LPS-activated monocytes deposited newly synthesized TNF-alpha into ECM-FN. FN-bound TNF-alpha (FN/TNF-alpha) significantly up-regulated MMP-9 expression and secretion by the human monocytic cell line MonoMac-6 and peripheral blood monocytes. Such secretion could be inhibited by antibodies that block TNF-alpha activity and binding to its receptors TNF RI (p55) and TNF RII (p75). Cheniotaxis through ECM gels in the presence of soluble or bound TNF-alpha was inhibited by a hydroxamic acid inhibitor of MMPs (GM6001). It is interesting that, although the adhesion of MonoMac-6 cells to FN/TNF-alpha required functional activated beta1 integrins, FN/TNF-alpha-induced MMP-9 secretion was independent of binding to beta1 integrins, since MMP-9 secretion was unaffected by: (1) neutralizing nAb to alpha4, alpha5, and beta1 subunits, which blocked cell adhesion; (2) a mAb that stimulated beta1 integrin-mediated adhesion; and (3) binding TNF-alpha to the 30-kDa amino-terminal fragment of FN, which lacks the major cell adhesive binding sites. Thus, in addition to their cell-adhesive roles, ECM glycoproteins, such as FN, may play a pivotal role in presenting proinflammatory cytokines to leukocytes within the actual inflamed tissue, thereby affecting their capacities to secrete ECM-degrading enzymes. These TNF-alpha-ECM interactions may serve to limit the cytokine's availability and bioactivity to target areas of inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • Cell Adhesion / drug effects
  • Cell Adhesion / physiology
  • Chemotaxis, Leukocyte / drug effects*
  • Chemotaxis, Leukocyte / physiology
  • Extracellular Matrix / metabolism
  • Extracellular Matrix / physiology
  • Fibronectins / metabolism
  • Fibronectins / pharmacology*
  • Humans
  • Integrins / physiology
  • Matrix Metalloproteinase 9 / biosynthesis*
  • Matrix Metalloproteinase 9 / metabolism
  • Monocytes / cytology
  • Monocytes / drug effects
  • Monocytes / enzymology*
  • Receptors, Tumor Necrosis Factor / physiology
  • Tumor Necrosis Factor-alpha / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology*


  • Fibronectins
  • Integrins
  • Receptors, Tumor Necrosis Factor
  • Tumor Necrosis Factor-alpha
  • Matrix Metalloproteinase 9