Fibronectin and its alpha 5 beta 1-integrin receptor are involved in the wound-repair process of airway epithelium

Abstract

The cell migration that occurs during wound repair is dependent on modifications of the cell-matrix interaction in which extracellular matrix proteins and their receptors, the integrins, are involved. To study the interactions between airway epithelial cells and the extracellular matrix during the process of wound repair, we developed an in vitro wound model of human epithelial cells. Surface epithelial cells were dissociated from human nasal polyps and cultured on a type I collagen matrix. At confluency, a wound was made by the addition of 2 microliters of NaOH (1 N) to the cell culture. After the cell culture was washed, the wound area was recorded every 12 h for 96 h by a videomicroscopic technique. We calculated the wound-repair index that represents the decrease in the wound area per hour. Using immunofluorescence techniques, we first examined the localization, during wound repair, of fibronectin and of the beta 1-, alpha v-, alpha 2-, alpha 3-, and alpha 5-integrin subunits. Secondly, we carried out a series of wound-repair blocking experiments with the use of anti-integrin or anti-fibronectin antibodies diluted in the culture medium. We observed that fibronectin and the alpha 5- integrin subunit were exclusively expressed by the migratory cells in the wounded area. No difference in the localization of the alpha v-, alpha 2-, and alpha 3-integrin subunits was observed between the nonrepairing and repairing cells. The blocking experiments showed a significant decrease in the wound-repair index in the presence of either the anti-beta 1, -alpha 3, alpha 5, or the anti-fibronectin antibodies. Furthermore, the addition of fibronectin to the culture medium induced a significant increase in the wound repair index. These results suggest that fibronectin and the corresponding alpha 5 beta 1-integrin play an important role in the process of airway epithelium wound repair.

Fibronectin matrix polymerization regulates small airway epithelial cell migration

“…One of the early responses to airway injury is the migration of the remaining epithelial cells over a fibronectin-containing provisional matrix (5). Previous in vitro studies have demonstrated that fibronectin promotes the migration of airway epithelial cells (13). In the present study, we have extended these observations by demonstrating that airway epithelial cell migration requires the formation of fibronectin matrix fibrils.…”

“…Migrating airway epithelial cells continuously secrete and polymerize fibronectin into insoluble ECM fibrils (13). In an initial step of fibronectin matrix formation, cells bind the NH 2 -terminal region of fibronectin in a specific and saturable manner (22).…”

Overexpressed proprotein convertase 1/3 induces an epithelial-mesenchymal transition in airway epithelium

“…During the repair process after airway epithelial injury, cells actively synthesise a5-integrin at the leading edge of cells [19,20] and require a functional cooperation of integrins with MMP-14 for cell migration [17]. These proteins are PC substrates and activated MMP-14 can facilitate the maturation of pro-MMP-2 [17].…”

“…Since the upregulation of MMPs, a5-integrin and the ECM proteins collagen and fibronectin are common features of EMT [17][18][19][20], we assessed the expression levels of these genes in mock and PC1/3 cells using realtime PCR. Figure 5a shows that PC1/3 overexpression resulted in markedly enhanced expression of MMP-2, MMP-3, and a5-integrin in NCI-H292 cells, while the expression levels of MMP-1, -7, -9 and -10 were not changed; increased MMP-2 expression was confirmed by Western blotting and zymography ( fig.…”

A multi-domain protein for β1 integrin-targeted DNA delivery

“…Apical expression of ␤ 1 integrins has been observed on epithelial cells during inflammation, wound healing and ischaemia. [15][16][17] Endothelial cells also express apical ␤ 1 integrins, which are involved in interactions with leukocytes when activated during the process of inflammation. 18 In conclusion, ␤ 1 integrins are available to external ligands, especially during clinically relevant conditions.…”