Evaluation of basement membrane degradation during TNF-α-induced increase in epithelial permeability

Jean Claude Lacherade, Andry Van De Louw, Emmanuelle Planus, Estelle Escudier, Marie Pia D'Ortho, Chantal Lafuma, Alain Harf, Christophe Delclaux

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


We evaluated whether tumor necrosis factor (TNF)-α induces an increase in permeability of an alveolar epithelial monolayer via gelatinase secretion and basement membrane degradation. Gelatinase secretion and epithelial permeability to radiolabeled albumin under unstimulated and TNF-α-stimulated conditions of an A549 human epithelial cell line were evaluated in vitro. TNF-α induced both upregulation of a 92-kDa gelatinolytic activity (pro form in cell supernatant and activated form in extracellular matrix) and an increase in the epithelial permeability coefficient compared with the unstimulated condition (control: 1.34 ± 0.04 × 10-6 cm/s; 1 μg/ml TNF-α: 1.47 ± 0.05 × 10-6 cm/s, P < 0.05). The permeability increase in the TNF-α-stimulated condition involved both paracellular permeability, with gap formation visualized by actin cytoskeleton staining, and basement membrane permeability, with an increase in the basement membrane permeability coefficient (determined after cell removal; control: 2.58 ± 0.07 × 10-6 cm/s; 1 μg/ml TNF-α: 2.82 ± 0.02.10-6 × cm/s, P < 0.05). Because addition of gelatinase inhibitors [tissue inhibitor of metalloproteinase (TIMP)-1 or BB-3103] to cell supernatants failed to inhibit the permeability increase, the gelatinase-inhibitor balance in the cellular microenvironment was further evaluated by cell culture on a radiolabeled collagen matrix. In the unstimulated condition, spontaneous collagenolytic activity inhibited by addition to the matrix of 1 μg/ml TIMP-1 or 10-6 M BB-3103 was found. TNF-α failed to increase this collagenolytic activity because it was associated with dose-dependent upregulation of TIMP-1 secretion by alveolar epithelial cells. In conclusion, induction by TNF-α of upregulation of both the 92-kDa gelatinase and its inhibitor TIMP-1 results in maintenance of the gelatinase-inhibitor balance, indicating that basement membrane degradation does not mediate the TNFα-induced increase in alveolar epithelial monolayer permeability.

Original languageEnglish (US)
Pages (from-to)L134-L143
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Issue number1 25-1
StatePublished - 2001

All Science Journal Classification (ASJC) codes

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology


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