Collaborative interactions between neutrophil elastase and metalloproteinases in extracellular matrix degradation in three-dimensional collagen gels

BACKGROUND: Extended culture of monocytes and fibroblasts in three-dimensional collagen gels leads to degradation of the gels (see linked study in this issue, "Fibroblasts and monocytes contract and degrade three-dimensional collagen gels in extended co-culture"). The current study, therefore, was designed to evaluate production of matrix-degrading metalloproteinases by these cells in co-culture and to determine if neutrophil elastase could collaborate in the activation of these enzymes. Since co-cultures produce prostaglandin E(2) (PGE(2)), the role of PGE(2) in this process was also evaluated. METHODS: Blood monocytes from healthy donors and human fetal lung fibroblasts were cast into type I collagen gels and maintained in floating cultures for three weeks. Matrix metalloproteinases (MMPs) were assessed by gelatin zymography (MMPs 2 and 9) and immunoblotting (MMPs 1 and 3). The role of PGE(2) was explored by direct quantification, and by the addition of exogenous indomethacin and/or PGE(2). RESULTS: Gelatin zymography and immunoblots revealed that MMPs 1, 2, 3 and 9 were induced by co-cultures of fibroblasts and monocytes. Neutrophil elastase added to the medium resulted in marked conversion of latent MMPs to lower molecular weight forms consistent with active MMPs, and was associated with augmentation of both contraction and degradation (P < 0.01). PGE(2) appeared to decrease both MMP production and activation. CONCLUSION: The current study demonstrates that interactions between monocytes and fibroblasts can mediate tissue remodeling

Fibroblasts and monocyte macrophages contract and degrade three-dimensional collagen gels in extended co-culture

BACKGROUND: Inflammatory cells are believed to play a prominent role during tissue repair and remodeling. Since repair processes develop and mature over extended time frames, the present study was designed to evaluate the effect of monocytes and fibroblasts in prolonged culture in three-dimensional collagen gels. METHODS: Blood monocytes from healthy donors and human fetal lung fibroblasts were cast into type I collagen gels and maintained in floating cultures for three weeks. RESULTS: Fibroblast-mediated gel contraction was initially inhibited by the presence of monocytes (P < 0.01). However, with extended co-culture, contraction of the collagen gels was greatly augmented (P < 0.01). In addition, with extended co-culture, degradation of collagen in the gels occurred. The addition of neutrophil elastase to the medium augmented both contraction and degradation (P < 0.01). Prostaglandin E(2) production was significantly increased by co-culture and its presence attenuated collagen degradation. CONCLUSION: The current study, therefore, demonstrates that interaction between monocytes and fibroblasts can contract and degrade extracellular matrix in extended culture

Banking system reform, earnings quality and credit allocation

This paper investigates credit allocation before and after the 2003 banking system reform in China. We find that relationships between earnings quality and new short-term loans, long-term loans and total loans in listed companies changed significantly after the banking system reform, especially in state-owned listed companies. Further investigation shows that due to the influence of rent-seeking, banks have eased the earnings requirements of non-state-owned listed companies. These findings enhance our understanding of the economic consequences of the banking system reform and of credit discrimination under the new regime

Endocarditis induced by M. morganii in an immunocompetent patient without underlying valvular abnormalities

Background: The gram-positive cocci is the most common pathogens of infective endocarditis (IE), and it is rarely induced by gram negative bacteria. Only one prior case has been described, in which a patient reported with IE caused by M. morganii, who suffered from multiple myeloma and received high dosages of corticosteroids, chemotherapy and immunomodulatory agents. IE is seldom diagnosed in patients without underlying valvular abnormalities. The most important risk factors of IE are intravenous drug abuse, implanted foreign material and central venous catheterization. Case summary: We describe a case of 34-year-old patient presented to the hospital with recurrent fever and pneumonia since 5 months. He was diagnosed with infective endocarditis with tricuspid vegetation by transthoracic echocardiography (TTE). Two blood culture tests demonstrated the growth of M. morganii, which was further confirmed by a NGS test, as well as a culture of vegetation from the tricuspid. All the evidence confirmed that M. morganii was the causative pathogen of the endocarditis in this case. The IE in an immunocompetent patient without underlying valvular abnormalities had been cured with broad antibiotic therapy and surgical intervention. Conclusion: This was a unique case of IE induced by an extremely rare agent in an immunocompetent patient without underlying valvular abnormalities. Broad-antibiotics with β-lactam enzyme inhibition should be used on time for M. morganii induced IE with bacteraemia. The operation to curette the vegetation and repair the tricuspid was also an important way to cure the endocarditis in the patient without underlying valvular abnormalities and with repeated episodes of blood stream and lung infections

Gold-Catalyzed Simultaneous Formation of C–C, CO, and C–F bonds in the Presence of Selectfluor: A Synthesis of Fluoroindenes from Allene Esters

An approach for the synthesis of fluorinated indene derivatives has been developed via a gold-catalyzed three-component tandem reaction between allene esters, Selectfluor, and water

Modification of type I collagenous gels by alveolar epithelial cells

Contraction of type I collagen gels is an in vitro model of tissue remodeling. In addition to fibroblasts, some epithelial cells can mediate this process. We therefore hypothesized that alveolar epithelial cells might contract extracellular matrices and have the potential to directly participate in the remodeling of the lung after alveolar injury. A549 cells were plated on top of collagen gels, and the gels were floated in culture medium. A549 cells contracted the gels in a time- and cell density–dependent manner. A549 cells, as well as human bronchial epithelial cells (HBEC) and rat alveolar epithelial cells (RalvEC) contracted collagen gels more when they were plated on top of the gel than when they were embedded inside, in contrast to human fetal lung fibroblast (HFL1), which contracted more when cast inside. The amount of hydroxyproline in the collagen gels remained unchanged throughout the contraction. Anti– β1 integrin antibody inhibited A549 cell–mediated contraction. Transforming growth factor β a..

Cigarette smoke inhibits human bronchial epithelial cell repair processes.

By interfering with the ability of airway epithelial cells to support repair processes, cigarette smoke could contribute to alterations of airway structures and functions that characterize chronic obstructive pulmonary disease (COPD). The current study assessed the ability of cigarette smoke extract (CSE) to alter human airway epithelial cell chemotaxis, proliferation, and contraction of three-dimensional collagen gels, a model of extracellular matrix remodeling. The volatile components contained in cigarette smoke, acetaldehyde and acrolein, were able to inhibit all three processes. Nonvolatile components contained within lyophilized CSE also inhibited chemotaxis but displayed no activity in the other two bioassays. CSE also inhibited the ability of airway epithelial cells to release transforming growth factor (TGF)- β and fibronectin. Exogenous fibronectin was unable to restore epithelial cell contraction of collagen gels. Exogenous TGF- β partially restored the ability of airway epithelial cells to con..

Human neutrophil elastase augments fibroblast-mediated contraction of released collagen gels.

In the present study, we tested the hypothesis that neutrophil elastase (NE) might mediate remodeling of extracellular matrix by affecting fibroblast-mediated contraction of three-dimensional collagen gels. Human lung fibroblasts were cast into type I collagen gels containing NE. After gelation, the gels were released into medium and the area was measured by image analyzer. NE augmented gel contraction (p < 0.001). This was not due to cell proliferation or to degradation to soluble collagen fragments because the amounts of DNA and hydroxyproline were not altered. α1-Protease inhibitor and the synthetic inhibitor of NE, L-680,833, when added in sufficient amount to inhibit free elastase activity, blocked the contraction induced by NE. Furthermore, neutrophil granulocytes (PMN) in coculture, as well as conditioned media from PMN, resulted in an increased contractility (p < 0.001 for both). Bronchoalveolar lavage fluid (BALF) from patients with increased PMN in their lower respiratory tract and free elastase..