Airway remodeling is a central feature of asthma; however, the mechanisms underlying its development have not been fully elucidated. We have demonstrated that osteopontin, an inflammatory cytokine and an extracellular matrix glycoprotein with profibrotic properties, is up-regulated in a murine model of allergen-induced airway remodeling. In the present study, we determined whether osteopontin plays a functional role in airway remodeling. Osteopontin (OPN)-deficient (OPN(-/-)) and wild-type mice were sensitized and exposed to inhaled ovalbumin (OVA) or saline for 5 weeks. Collagen production, peribronchial smooth muscle area, mucus-producing cell number, and bronchoalveolar cell counts were assessed. The functional behavior and phenotype of lung fibroblasts from OVA-treated OPN(-/-) and from wild-type mice were studied using ex vivo cultures. OVA-treated OPN(-/-) mice exhibited reduced lung collagen content, smooth muscle area, mucus-producing cells, and inflammatory cell accumulation as compared with wild-type mice. Reduced matrix metalloproteinase-2 activity and expression of transforming growth factor-beta1 and vascular endothelial growth factor were observed in OVA-treated OPN(-/-) mice. Lung fibroblasts from OVA-treated OPN(-/-) mice showed reduced proliferation, migration, collagen deposition, and alpha-smooth muscle actin expression in comparison with OVA-treated wild-type lung fibroblasts. Thus, OPN is key for the development of allergen-induced airway remodeling in mice. In response to allergen, OPN induces the switching of lung fibroblasts to a pro-fibrogenic myofibroblast phenotype.
"In addition, for the first time, we investigated the impact of AT on the expression of OPN, a cytokine directly involved in the AR by inducing increase in the ASM, and epithelium thickness, and airway fibrosis (Kohan et al., 2009; Simoes et al., 2009). Our results show that AT reversed the OVA-induced expression of OPN at the later time point (15 days). "
"OPN is a phosphorylated acidic arginine-glycine-aspartate (RGD)-containing glycoprotein that exists both as an immobilized ECM component and as a soluble multifunctional proinflammatory cytokine, which play important roles in promoting inflammation [29,30], tissue remodeling, fibrosis [29,31-34], and angiogenesis [35-38]. Many of these effects are mediated by the binding of OPN to CD44 receptors and the surface integrin receptor αvβ3 [35,36,39]. "
[Show abstract][Hide abstract] ABSTRACT: Purpose: The calcium-binding protein S100A4 is implicated in cancer cell invasion and metastasis, the stimulation of angiogenesis, the progression of fibrosis, and inflammatory disorders. We investigated the expression of S100A4 and correlated it with clinical disease activity as well as with the levels of osteopontin (OPN), soluble syndecan-1, and vascular endothelial growth factor (VEGF) in proliferative diabetic retinopathy (PDR). To reinforce the findings at the functional level, we examined the expressions of S100A4 and OPN in the retinas of diabetic rats and in human retinal microvascular endothelial cells (HRMECs) following exposure to VEGF and the proinfammatory cytokine tumor necrosis factor-α (TNF-α).
"The color segmentation protocols were utilized in the IPP6.0 system to obtain the data. The area of α-SMA and type I collagen immunostaining in the small airway wall was quantitatively analyzed . The expression of MMP9, MMP2 and TIMP1 in the small airway wall was quantified by measuring the integrated optical density (IOD) of the positive staining area. "
[Show abstract][Hide abstract] ABSTRACT: Peribronchiolar fibrosis is an important feature of small airway remodeling (SAR) in cigarette smoke-induced COPD. The aim of this study was to investigate the role of gelatinases (MMP9, MMP2) and epithelial-mesenchymal transition (EMT) in SAR related to wood smoke (WS) exposure in a rat model.
Forty-eight female Sprague-Dawley rats were randomly divided into the WS group, the cigarette smoke (CS) group and the clean air control group. After 4 to 7 months of smoke exposure, lung tissues were examined with morphometric measurements, immunohistochemistry and Western blotting. Serum MMP9 and TIMP1 concentrations were detected by ELISA. In vitro, primary rat tracheal epithelial cells were stimulated with wood smoke condensate for 7 days.
The COPD-like pathological alterations in rats exposed chronically to WS were similar to those exposed to CS; the area of collagen deposition was significantly increased in the small airway walls of those exposed to WS or CS for 7 months. The expression of gelatinases in rats induced by WS or CS exposure was markedly increased in whole lung tissue, and immunohistochemistry showed that MMP9, MMP2 and TIMP1 were primarily expressed in the airway epithelium. The serum levels of MMP9 and TIMP1 were significantly higher in rats secondary to WS or CS exposure. Few cells that double immunostained for E-cadherin and vimentin were observed in the airway subepithelium of rats exposed to WS for 7 months (only 3 of these 8 rats). In vitro, the expression of MMP9 and MMP2 proteins was upregulated in primary rat tracheal epithelial cells following exposure to wood smoke condensate for 7 days by Western blotting; positive immunofluorescent staining for vimentin and type I collagen was also observed.
These findings suggest that the upregulation of gelatinases and EMT might play a role in SAR in COPD associated with chronic exposure to wood smoke.
PLoS ONE 05/2014; 9(5):e96708. DOI:10.1371/journal.pone.0096708 · 3.23 Impact Factor
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