Cigarette smoke represses the innate immune response to asbestos.

Both cigarette smoke (CS) and asbestos cause lung inflammation and lung cancer, and at high asbestos exposure levels, populations exposed to both of these carcinogens display a synergistic increase in the development of lung cancer. The mechanisms through which these two toxic agents interact to promote lung tumorigenesis are poorly understood. Here, we begin to dissect the inflammatory signals induced by asbestos in combination with CS using a rodent inhalation model and in vitro cell culture.

Chronic treatment in vivo with β-adrenoceptor agonists induces dysfunction of airway β(2) -adrenoceptors and exacerbates lung inflammation in mice.

Background And Purpose: Inhalation of a β-adrenoceptor agonist (β-agonist) is first-line asthma therapy, used for both prophylaxis against, and acute relief of, bronchoconstriction. However, repeated clinical use of β-agonists leads to impaired bronchoprotection and, in some cases, adverse patient outcomes. Mechanisms underlying this β(2) -adrenoceptor dysfunction are not well understood, due largely to the lack of a comprehensive animal model and the uncertainty as to whether or not bronchorelaxation in mice is mediated by β(2) -adrenoceptors.

Characterization of side population cells in human malignant mesothelioma cell lines.

Side population (SP) assay composed of Hoechst 33342 staining and subsequent flow cytometric analysis has been widely utilized for characterizing putative cancer stem cells (CSCs) in various human malignancies. The present study was designed to evaluate the SP assay as a research tool for mesothelial CSCs. A distinct fraction of SP cells was identified in various human malignant mesothelioma (HMM) cell lines, ranging from 0.

Mesenchymal stem cells modulate lung injury.

Mesenchymal stem cells (MSCs) have been shown to differentiate into a variety of mesenchymal cell types, including fibroblasts, myofibroblasts, osteoblasts, chondroblasts, adipocytes, and myoblasts, as well as epithelial cells. It has been shown that these cells can be recovered from bone marrow as well as umbilical cord blood, and they can be propagated, stored, and administered to animals and patients in clinical trials. It is clear that the cells engraft in the lung, and several laboratories have demonstrated an ameliorating effect in models of acute injury caused by LPS and in chronic lung injury induced by bleomycin and asbestos.

Mesenchymal stem cells require MARCKS protein for directed chemotaxis in vitro.

Mesenchymal stem cells (MSCs) reside within tissues such as bone marrow, cord blood, and dental pulp and can differentiate into other mesenchymal cell types. Differentiated MSCs, called circulating fibrocytes, have been demonstrated in human lungs and migrate to injured lung tissue in experimental models. It is likely that MSCs migrate from the bone marrow to sites of injury by following increasing chemokine concentrations.

TNF-alpha induces TGF-beta1 expression in lung fibroblasts at the transcriptional level via AP-1 activation.

Tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta(1) (TGF-beta(1)) are peptides with multiple biological activities that influence neoplastic, immunologic and fibroproliferative diseases. There are clear interrelationships and overlap between the actions of TNF-alpha and TGF-beta(1) in lung fibrosis; therefore, we postulated that TNF-alpha may play a significant role in regulating TGF-beta(1) expression in lungs. We recently reported that TNF-alpha activates the extracellular regulated kinase (ERK)-specific pathway in fibroblasts resulting in stabilization of TGF-beta(1) mRNA and increased expression of TGF-beta(1).

Inhaled carbon nanotubes reach the subpleural tissue in mice.

Carbon nanotubes are shaped like fibres and can stimulate inflammation at the surface of the peritoneum when injected into the abdominal cavity of mice, raising concerns that inhaled nanotubes may cause pleural fibrosis and/or mesothelioma. Here, we show that multiwalled carbon nanotubes reach the subpleura in mice after a single inhalation exposure of 30 mg m(-3) for 6 h. Nanotubes were embedded in the subpleural wall and within subpleural macrophages.

Mesenchymal stem cells produce Wnt isoforms and TGF-beta1 that mediate proliferation and procollagen expression by lung fibroblasts.

Studies have been carried out previously to determine whether mesenchymal stem cells (MSC) influence the progression of pulmonary fibrosis. Here, we asked whether MSC (derived from mouse bone marrow and human umbilical cord blood) produce factors that mediate lung fibroblast (LF) growth and matrix production. MSC-conditioned media (CM) were found by ELISA to contain significant amounts of PDGF-AA and transforming growth factor-beta1 (TGF-beta1).

Knowns and unknowns of the alveolus.

Our current alveolar paradigm includes three highly specialized cell populations. Alveolar type I cells are flat, elongated cells that presumably enable gas exchange. Alveolar type II cells are small, cuboidal cells with metabolic, secretory, progenitor, and immunologic functions.

Resident cellular components of the human lung: current knowledge and goals for research on cell phenotyping and function.

The purpose of the workshop was to identify still obscure or novel cellular components of the lung, to determine cell function in lung development and in health that impacts on disease, and to decide promising avenues for future research to extract and phenotype these cells. Since robust technologies are now available to identify, sort, purify, culture, and phenotype cells, progress is now within sight to unravel the origins and functional capabilities of lung cells in developmental stages and in disease. The Workshop's agenda was to first discuss the lung's embryologic development, including progenitor and stem cells, and then assess the functional and structural cells in three main compartments of the lung: (1) airway cells in bronchial and bronchiolar epithelium and bronchial glands (basal, secretory, ciliated, Clara, and neuroendocrine cells); (2) alveolar unit cells (Type 1 cells, Type 2 cells, and fibroblasts in the interstitium); and (3) pulmonary vascular cells (endothelial cells from different vascular structures, smooth muscle cells, and adventitial fibroblasts).

The latent form of TGFbeta(1) is induced by TNFalpha through an ERK specific pathway and is activated by asbestos-derived reactive oxygen species in vitro and in vivo.

Tumor necrosis factor-alpha (TNFalpha) and transforming growth factor-beta(1) (TGFbeta(1)) are potent peptide growth factors that are likely to play important roles in the development of interstitial pulmonary fibrosis (IPF). Previously we showed that TNFalpha and TGFbeta(1) are up-regulated in macrophages, epithelial and mesenchymal cells early after exposure to chrysotile asbestos, particularly at sites of fiber deposition in vivo. We also showed that TNFalpha receptor knockout mice are resistant to asbestos-induced fibrosis.

Laser capture microdissection reveals dose-response of gene expression in situ consequent to asbestos exposure.

The genes that mediate fibroproliferative lung disease remain to be defined. Prior studies from our laboratory showed by in situ hybridization and immunohistochemistry that the genes coding for tumour necrosis factor alpha, transforming growth factor beta, the platelet-derived growth factor A and B isoforms, and alpha-1 pro-collagen are expressed in fibroproliferative lesions that develop quickly after asbestos inhalation. These five genes, along with matrix metalloproteinase 9, a collagenase found to be increased in several lung diseases, are known to control matrix production and cell proliferation in humans and animals.

Engraftment of bone marrow progenitor cells in a rat model of asbestos-induced pulmonary fibrosis.

Rationale: Bone marrow-derived cells have been shown to engraft during lung fibrosis. However, it is not known if similar cells engraft consequent to inhalation of asbestos fibers that cause pulmonary fibrosis, or if the cells proliferate and differentiate at sites of injury.

Objectives: We examined whether bone marrow-derived cells participate in the pulmonary fibrosis that is produced by exposure to chrysotile asbestos fibers.

Tumor necrosis factor-alpha induces transforming growth factor-beta1 expression in lung fibroblasts through the extracellular signal-regulated kinase pathway.

Increased expression of transforming growth factor (TGF)-beta(1) and tumor necrosis factor (TNF)-alpha are thought to play important roles in the development of pulmonary fibrosis. We recently reported that TNF-alpha upregulates TGF-beta(1) expression in primary mouse lung fibroblasts (MLFs), a key cell population in fibrogenesis. In the present study, we have investigated signal transduction pathways involved in TNF-alpha upregulation of TGF-beta(1) in both primary MLFs and the Swiss 3T3 fibroblast cell line.

Pathogenesis of pleural fibrosis.

Pleural fibrosis resembles fibrosis in other tissues and can be defined as an excessive deposition of matrix components that results in the destruction of normal pleural tissue architecture and compromised function. Pleural fibrosis may be the consequence of an organised haemorrhagic effusion, tuberculous effusion, empyema or asbestos-related pleurisy and can manifest itself as discrete localised lesions (pleural plaques) or diffuse pleural thickening and fibrosis. Although the pathogenesis is unknown, it is likely that the complex interactions between resident and inflammatory cells, profibrotic mediators and coagulation, and fibrinolytic pathways are integral to pleural remodelling and fibrosis.

Phospho-Akt overexpression in non-small cell lung cancer confers significant stage-independent survival disadvantage.

Purpose: Akt is a signal transduction protein that plays a central role in inhibiting apoptosis in a variety of cell types including human cancer cells. In cell lines derived from human non-small cell lung cancers (NSCLCs), Akt has been shown to confer chemoresistance by inhibition of apoptosis in response to different chemotherapeutic agents including platinum-based agents, which are often the first-line therapy for NSCLCs. Only 20% to 30% of patients with NSCLC treated with chemotherapy have clinical evidence of response.

Asbestos-derived reactive oxygen species activate TGF-beta1.

Transforming growth factor-beta1 (TGF-beta1) is a potent peptide that inhibits epithelial and mesenchymal cell proliferation and stimulates the synthesis of extracellular matrix components. This cytokine is produced in a biologically latent complex bound to a latent-associated peptide (LAP), and it is the disassociation of this complex that regulates TGF-beta activity. A number of mechanisms have been shown to activate TGF-beta1.

Titration of non-replicating adenovirus as a vector for transducing active TGF-beta1 gene expression causing inflammation and fibrogenesis in the lungs of C57BL/6 mice.

Investigators have shown that interstitial pulmonary fibrosis (IPF) can be induced in rats by overexpressing transforming growth factor beta1 (TGF-beta1) through a replication-deficient recombinant adenovirus vector instilled into the lungs (Sime et al. 1997). We have shown that this vector induces IPF in fibrogenic-resistant tumour necrosis factor alpha-receptor knockout (TNF-alphaRKO) mice (Liu et al.

Susceptibility to asbestos-induced and transforming growth factor-beta1-induced fibroproliferative lung disease in two strains of mice.

Pulmonary fibrosis (PF) is caused by a number of inhaled agents, as well as by some drugs and toxic particles. The elaboration of certain peptide growth factors is thought to be key to the development of this disease process. In addition, genetic susceptibility plays a role in the development of PF.