Redistribution of pulmonary EC-SOD after exposure to asbestos

2004 ◽  
Vol 97 (5) ◽  
pp. 2006-2013 ◽  
Author(s):  
Roderick J. Tan ◽  
Cheryl L. Fattman ◽  
Simon C. Watkins ◽  
Tim D. Oury
Keyword(s):  
Extracellular Matrix ◽  
Lung Injury ◽  
Asbestos Exposure ◽  
Intratracheal Instillation ◽  
Inflammatory Cells ◽  
Lung Parenchyma ◽  
Lavage Fluid ◽  
Binding Domain ◽  
Heparin Binding ◽  
Heparin Binding Domain

Inhalation of asbestos fibers leads to interstitial lung disease (asbestosis) characterized by inflammation and fibrosis. The pathogenesis of asbestosis is not fully understood, but reactive oxygen species are thought to play a central role. Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme that protects the lung in a bleomycin-induced pulmonary fibrosis model, but its role has not been studied in asbestos-mediated disease. EC-SOD is found in high levels in the extracellular matrix of lung alveoli because of its positively charged heparin-binding domain. Proteolytic removal of this domain results in clearance of EC-SOD from the matrix of tissues. We treated wild-type C57BL/6 mice with 0.1 mg of crocidolite asbestos by intratracheal instillation and euthanized them 24 h later. Compared with saline- or titanium dioxide-treated control mice, bronchoalveolar lavage fluid (BALF) from asbestos-treated mice contained significantly higher total protein levels and increased numbers of inflammatory cells, predominantly neutrophils, indicating acute lung injury in response to asbestos. Decreased EC-SOD protein and activity were found in the lungs of asbestos-treated mice, whereas more EC-SOD was found in the BALF of these mice. The EC-SOD in the BALF was predominantly in the proteolyzed form, which lacks the heparin-binding domain. This redistribution of EC-SOD correlated with development of fibrosis 14 days after asbestos exposure. These data suggest that asbestos injury leads to enhanced proteolysis and clearance of EC-SOD from lung parenchyma into the air spaces. The depletion of EC-SOD from the extracellular matrix may increase susceptibility of the lung to oxidative stress during asbestos-mediated lung injury.

scholarly journals Anti-Inflammatory Effects of Monoammonium Glycyrrhizinate on Lipopolysaccharide-Induced Acute Lung Injury in Mice through Regulating Nuclear Factor-Kappa B Signaling Pathway

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaoying Huang ◽  
Jiangfeng Tang ◽  
Hui Cai ◽  
Yi Pan ◽  
Yicheng He ◽  
...  
Keyword(s):  
Acute Lung Injury ◽  
Lung Injury ◽  
Signaling Pathway ◽  
Interleukin 1 ◽  
Intratracheal Instillation ◽  
Weight Ratio ◽  
Dry Weight ◽  
Inflammatory Cells ◽  
Lavage Fluid ◽  
Therapeutic Mechanism

The present study aimed to investigate the therapeutic effect of monoammonium glycyrrhizinate (MAG) on lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in mice and possible mechanism. Acute lung injury was induced in BALB/c mice by intratracheal instillation of LPS, and MAG was injected intraperitoneally 1 h prior to LPS administration. After ALI, the histopathology of lungs, lung wet/dry weight ratio, protein concentration, and inflammatory cells in the bronchoalveolar lavage fluid (BALF) were determined. The levels of tumor necrosis factor-α(TNF-α) and interleukin-1β(IL-1β) in the BALF were measured by ELISA. The activation of NF-κB p65 and IκB-αof lung homogenate was detected by Western blot. Pretreatment with MAG attenuated lung histopathological damage induced by LPS and decreased lung wet/dry weight ratio and the concentrations of protein in BALF. At the same time, MAG reduced the number of inflammatory cells in lung and inhibited the production of TNF-αand IL-1βin BALF. Furthermore, we demonstrated that MAG suppressed activation of NF-κB signaling pathway induced by LPS in lung. The results suggested that the therapeutic mechanism of MAG on ALI may be attributed to the inhibition of NF-κB signaling pathway. Monoammonium glycyrrhizinate may be a potential therapeutic reagent for ALI.

scholarly journals Molecular Mapping and Functional Characterization of the VEGF164 Heparin-binding Domain

2007 ◽  
Vol 282 (38) ◽  
pp. 28045-28056 ◽  
Author(s):  
Dominik Krilleke ◽  
Andrea DeErkenez ◽  
William Schubert ◽  
Indrajit Giri ◽  
Gregory S. Robinson ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Molecular Mapping ◽  
Functional Characterization ◽  
Binding Activity ◽  
Binding Domain ◽  
Site Directed Mutagenesis ◽  
Heparin Binding ◽  
Splice Isoforms ◽  
Tissue Samples ◽  
Heparin Binding Domain

The longer splice isoforms of vascular endothelial growth factor-A (VEGF-A), including mouse VEGF164, contain a highly basic heparin-binding domain (HBD), which imparts the ability of these isoforms to be deposited in the heparan sulfate-rich extracellular matrix and to interact with the prototype sulfated glycosaminoglycan, heparin. The shortest isoform, VEGF120, lacks this highly basic domain and is freely diffusible upon secretion. Although the HBD has been attributed significant relevance to VEGF-A biology, the molecular determinants of the heparin-binding site are unknown. We used site-directed mutagenesis to identify amino acid residues that are critical for heparin binding activity of the VEGF164 HBD. We focused on basic residues and found Arg-13, Arg-14, and Arg-49 to be critical for heparin binding and interaction with extracellular matrix in tissue samples. We also examined the cellular and biochemical consequences of abolishing heparin-binding function, measuring the ability of the mutants to interact with VEGF receptors, induce endothelial cell gene expression, and trigger microvessel outgrowth. Induction of tissue factor expression, vessel outgrowth, and binding to VEGFR2 were unaffected by the HBD mutations. In contrast, the HBD mutants showed slightly decreased binding to the NRP1 (neuropilin-1) receptor, and analyses suggested the heparin and NRP1 binding sites to be distinct but overlapping. Finally, mutations that affect the heparin binding activity also led to an unexpected reduction in the affinity of VEGF164 binding specifically to VEGFR1. This finding provides a potential basis for previous observations suggesting enhanced potency of VEGF164 versus VEGF120 in VEGFR1-mediated signaling in inflammatory cells.

Depletion of pulmonary EC-SOD after exposure to hyperoxia

2002 ◽  
Vol 283 (4) ◽  
pp. L777-L784 ◽  
Author(s):  
Tim D. Oury ◽  
Lisa M. Schaefer ◽  
Cheryl L. Fattman ◽  
Augustine Choi ◽  
Karen E. Weck ◽  
...  
Keyword(s):  
Bronchoalveolar Lavage Fluid ◽  
Lavage Fluid ◽  
Binding Domain ◽  
Extracellular Superoxide Dismutase ◽  
Pulmonary Injury ◽  
Heparin Binding ◽  
Cell Surfaces ◽  
Heparin Binding Domain ◽  
High Concentrations ◽  
Alveolar Parenchyma

Extracellular superoxide dismutase (EC-SOD) is highly expressed in lung tissue. EC-SOD contains a heparin-binding domain that is sensitive to proteolysis. This heparin-binding domain is important in allowing EC-SOD to exist in relatively high concentrations in specific regions of the extracellular matrix and on cell surfaces. EC-SOD has been shown to protect the lung against hyperoxia in transgenic and knockout studies. This study tests the hypothesis that proteolytic clearance of EC-SOD from the lung during hyperoxia contributes to the oxidant-antioxidant imbalance that is associated with this injury. Exposure to 100% oxygen for 72 h resulted in a significant decrease in EC-SOD levels in the lungs and bronchoalveolar lavage fluid of mice. This correlated with a significant depletion of EC-SOD from the alveolar parenchyma as determined by immunofluorescence and immunohistochemistry. EC-SOD mRNA was unaffected by hyperoxia; however, there was an increase in the ratio of proteolyzed to uncut EC-SOD after hyperoxia, which suggests that hyperoxia depletes EC-SOD from the alveolar parenchyma by cutting the heparin-binding domain. This may enhance hyperoxic pulmonary injury by altering the oxidant-antioxidant balance in alveolar spaces.

scholarly journals The heparin binding domain of von Willebrand factor binds to growth factors and promotes angiogenesis in wound healing

Blood ◽  
2019 ◽  
Vol 133 (24) ◽  
pp. 2559-2569 ◽  
Author(s):  
Jun Ishihara ◽  
Ako Ishihara ◽  
Richard D. Starke ◽  
Claire R. Peghaire ◽  
Koval E. Smith ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Wound Healing ◽  
Growth Factors ◽  
Growth Factor ◽  
Von Willebrand Factor ◽  
Binding Domain ◽  
Heparin Binding ◽  
Heparin Binding Domain ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract During wound healing, the distribution, availability, and signaling of growth factors (GFs) are orchestrated by their binding to extracellular matrix components in the wound microenvironment. Extracellular matrix proteins have been shown to modulate angiogenesis and promote wound healing through GF binding. The hemostatic protein von Willebrand factor (VWF) released by endothelial cells (ECs) in plasma and in the subendothelial matrix has been shown to regulate angiogenesis; this function is relevant to patients in whom VWF deficiency or dysfunction is associated with vascular malformations. Here, we show that VWF deficiency in mice causes delayed wound healing accompanied by decreased angiogenesis and decreased amounts of angiogenic GFs in the wound. We show that in vitro VWF binds to several GFs, including vascular endothelial growth factor-A (VEGF-A) isoforms and platelet-derived growth factor-BB (PDGF-BB), mainly through the heparin-binding domain (HBD) within the VWF A1 domain. VWF also binds to VEGF-A and fibroblast growth factor-2 (FGF-2) in human plasma and colocalizes with VEGF-A in ECs. Incorporation of the VWF A1 HBD into fibrin matrices enables sequestration and slow release of incorporated GFs. In vivo, VWF A1 HBD-functionalized fibrin matrices increased angiogenesis and GF retention in VWF-deficient mice. Treatment of chronic skin wounds in diabetic mice with VEGF-A165 and PDGF-BB incorporated within VWF A1 HBD-functionalized fibrin matrices accelerated wound healing, with increased angiogenesis and smooth muscle cell proliferation. Therefore, the VWF A1 HBD can function as a GF reservoir, leading to effective angiogenesis and tissue regeneration.

scholarly journals Expression and analysis of COOH-terminal deletions of the human thrombospondin molecule.

1989 ◽  
Vol 109 (2) ◽  
pp. 843-852 ◽  
Author(s):  
E V Prochownik ◽  
K O'Rourke ◽  
V M Dixit
Keyword(s):  
Extracellular Matrix ◽  
Amino Acid ◽  
Solid Phase ◽  
Binding Domain ◽  
Heparin Binding ◽  
Disulphide Bridge ◽  
Cell Growth And Migration ◽  
African Green Monkey Kidney ◽  
Amino Terminal ◽  
Heparin Binding Domain

Thrombospondin (TSP) is a homotrimeric extracellular glycoprotein with a subunit molecular mass of 140 kD. The subunits have a modular or domain-like structure and are held together by interchain disulphide bonds. A number of domains have been identified including those for the binding of collagen, fibrinogen, and heparin. Due to the trimeric form of the TSP molecule, the various domains are trivalent in nature and this contributes to the ability of TSP to mediate cell-substrate interactions. Indeed, TSP has recently been shown not only to promote cell adhesion but also to be intimately involved in cell growth and migration. The adhesive function of TSP is attributable to the "solid-phase" or matrix-bound form of the molecule. There is some evidence that the heparin-binding domain mediates incorporation of soluble TSP into the insoluble matrix form. The heparin-binding domain of TSP is a compact globular amino-terminal moiety that contains two clusters of basic amino acids and a single intrachain disulphide bond. To delineate the role of the heparin-binding domain in matrix assembly and to define further the precise region of interchain disulphide bonding that results in trimer formation, we have expressed deleted forms of the cDNA encoding TSP in SV-40-transformed. African green monkey kidney cells. The proteins synthesized from the various deleted TSP cDNAs were examined for (a) secretion into the culture medium and incorporation into the extracellular matrix; (b) binding to heparin-Sepharose; (c) immunoprecipitability by a conformation-specific monoclonal antibody; and (d) ability to form trimers. This analysis allowed us to draw the following conclusions. (a) A 218 amino acid NH2-terminal protein that preserves the intrachain disulphide bridge of the heparin-binding domain is capable of binding to heparin-Sepharose and incorporating into the extracellular matrix. (b) A shorter 164 amino acid NH2-terminal peptide that does not contain the intrachain disulphide bridge of the heparin-binding domain is neither able to bind to heparin-Sepharose nor able to incorporate into the extracellular matrix. (c) The region of interchain disulphide bridging necessary for trimer assembly resides within a cluster of seven cysteine residues immediately adjacent to the heparin-binding domain.

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