Excessive fibrin deposition in nasal polyps caused by fibrinolytic impairment through reduction of tissue plasminogen activator expression

Am J Respir Crit Care Med. 2013 Jan 1;187(1):49-57. doi: 10.1164/rccm.201207-1292OC. Epub 2012 Nov 15.


Rationale: Nasal polyps (NPs) are characterized by intense edema or formation of pseudocysts filled with plasma proteins, mainly albumin. However, the mechanisms underlying NP retention of plasma proteins in their submucosa remain unclear.

Objectives: We hypothesized that formation of a fibrin mesh retains plasma proteins in NPs. We assessed the fibrin deposition and expression of the components of the fibrinolytic system in patients with chronic rhinosinusitis (CRS).

Methods: We assessed fibrin deposition in nasal tissue from patients with CRS and control subjects by means of immunofluorescence. Fibrinolytic components, d-dimer, and plasminogen activators were measured using ELISA, real-time PCR, and immunohistochemistry. We also performed gene expression and protein quantification analysis in cultured airway epithelial cells.

Measurements and main results: Immunofluorescence data showed profound fibrin deposition in NP compared with uncinate tissue (UT) from patients with CRS and control subjects. Levels of the cross-linked fibrin cleavage product protein, d-dimer, were significantly decreased in NP compared with UT from patients with CRS and control subjects, suggesting reduced fibrinolysis (P < 0.05). Expression levels of tissue plasminogen activator (t-PA) mRNA and protein were significantly decreased in NP compared with UT from patients with CRS and control subjects (P < 0.01). Immunohistochemistry demonstrated clear reduction of t-PA in NP, primarily in the epithelium and glands. Th2 cytokine-stimulated cultured airway epithelial cells showed down-regulation of t-PA, suggesting a potential Th2 mechanism in NP.

Conclusions: A Th2-mediated reduction of t-PA might lead to excessive fibrin deposition in the submucosa of NP, which might contribute to the tissue remodeling and pathogenesis of CRS with nasal polyps.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Blood Proteins / metabolism
  • Down-Regulation / physiology
  • Edema / metabolism
  • Epithelium / metabolism
  • Female
  • Fibrin / metabolism*
  • Fibrinolysis / physiology*
  • Fluorescent Antibody Technique
  • Humans
  • Male
  • Middle Aged
  • Nasal Mucosa / metabolism
  • Nasal Polyps / metabolism*
  • Th2 Cells / metabolism
  • Tissue Plasminogen Activator / metabolism*
  • Young Adult


  • Blood Proteins
  • Fibrin
  • Tissue Plasminogen Activator