Molecular mechanisms in chronic obstructive pulmonary disease: potential targets for therapy

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease associated with progressive airflow obstruction. Tobacco smoking is the main risk factor worldwide. In contrast to asthma, antiinflammatory therapies are rather ineffective in improving chronic symptoms and reducing inflammation, lung function decline, and airway remodeling. Specific drugs that are directed against the remodeling and chronic inflammation, thereby preventing lung tissue damage and progressive lung function decline, must be developed. Experimental models and expression studies suggest that anti-vascular endothelial growth factor (VEGF) receptor strategies may be of use in patients with emphysema, whereas anti-HER1-directed strategies may be more useful in patients with pulmonary mucus hypersecretion, as seen in chronic bronchitis and asthma. Growth factors and cytokines including VEGF, fibroblast growth factors, transforming growth factor-beta, tumor necrosis factor-alpha, CXCL1, CXCL8, and CCL2, and signal transduction proteins such as mitogen-activated protein kinase p38 and nuclear factor-kappaB, seem to be important pathogenetic molecules in COPD. Specific antagonists for these proteins may be effective for different inflammatory diseases. However, their efficacy for COPD therapy has not yet been demonstrated. Finally, other drugs such as retinoic acids may provide restoration of lung tissue structure. Such approaches, however, must await the first results of growth factor or cytokine antagonist therapy in chronic lung diseases.     

Molecular mechanisms in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease associated with progressive airflow obstruction. Tobacco smoking is the main risk factor worldwide. In contrast to asthma, anti-inflammatory therapies are rather ineffective in improving chronic symptoms and reducing inflammation, lung function decline, and airway remodeling. Specific drugs that are directed against the remodeling and chronic inflammation, thereby preventing lung tissue damage and progressive lung function decline, must be developed. Experimental models and expression studies suggest that anti-vascular endothelial growth factor (VEGF) receptor strategies may be of use in patients with emphysema, whereas anti-HER1-directed strategies may be more useful in patients with pulmonary mucus hypersecretion, as seen in chronic bronchitis and asthma. Growth factors and cytokines including VEGF, fibroblast growth factors, transforming growth factor-β, tumor necrosis factor-α, CXCL1, CXCL8, and CCL2, and signal transduction proteins such as mitogen-activated protein kinase p38 and nuclear factor-⦊B, seem to be important pathogenetic molecules in COPD. Specific antagonists for these proteins may be effective for different inflammatory diseases. However, their efficacy for COPD therapy has not yet been demonstrated. Finally, other drugs such as retinoic acids may provide restoration of lung tissue structure. Such approaches, however, must await the first results of growth factor or cytokine antagonist therapy in chronic lung diseases.     

Fibrosing alveolitis

Fibrosing alveolitis is a disease of unknown cause mainly involving the gas-exchanging portions of the lungs. It may occur in isolation and be called cryptogenic or idiopathic, in which case the clinical manifestations are mainly respiratory, or it may be associated with other disorders, such as rheumatoid arthritis. The histopathologic abnormalities of the pulmonary tissue are identical in either instance. Other names used for the disease have included usual interstitial pneumonia, desquamative interstitial pneumonia and the Hamman-Rich syndrome; these terms may describe different stages of the same pathologic process. Many authors in North America and those in the United Kingdom favour the term fibrosing alveolitis when describing chronic interstitial pneumonias. There may be accompanying nonspecific Immunologic abnormalities, which may denote that fibrosing alveolitis is part of the wide spectrum of diseases known as connective tissue disorders. Recently immune complexes have been found in the lung parenchyma; they probably result in the granulocyte destruction and reticuloendothelial proliferation seen in the acute phase of the disease.There are no specific diagnostic tests for the disease apart from lung biopsy, which can be performed at the time of thoracotomy or transbronchially, with the use of a flexible fibreoptic bronchoscope. Lavaged cells from the alveoli have also been obtained via the bronchoscope; in persons with fibrosing alveolitis a high proportion of these cells are neutrophils, and after corticosteroid treatment the proportion decreases. The progress of the disease can be followed by examination of these washings as well as by lung scanning with gallium-67 citrate. Newer methods of treatment using combinations of corticosteroids and immunosuppressant drugs are being evaluated and are initially proving to be successful.     

Programmatic change: lung disease research in the era of induced pluripotency

Human lung research has made remarkable progress over the last century largely through the use of animal models of disease. The challenge for the future is to translate these findings into human disease and bring about meaningful disease modification or even cure. The ability to generate transformative therapies in the future will require human tissue, currently scarce under the best of circumstances. Unfortunately, patient-derived somatic cells are often poorly characterized and have a limited life span in culture. Moreover, these cells are frequently obtained from patients with end-stage disease exposed to multiple drug therapies, leaving researchers with questions about whether their findings recapitulate disease-initiating processes or are simply the result of pharmacological intervention or subsequent host responses. The goal of studying early disease in multiple cell and tissue types has driven interest in the use of induced pluripotent stem cells (iPSCs) to model lung disease. These cells provide an alternative model for relevant lung research and hold promise in particular for studying the initiation of disease processes in genetic conditions such as heritable pulmonary arterial hypertension as well as other lung diseases. In this Perspective, we focus on potential iPSC use in pulmonary vascular disease research as a model for iPSC use in many types of advanced lung disease.     

Constitutive equations for the lung tissue

The mechanical behavior of the lung tissue (expressed by its constitutive equations) has considerable influence on the normal and pathological function of the lung. It determines the stress field in the tissue, thus affecting the impedence and energy consumption during breathing as well as the localization of certain lung diseases. The lung tissue has a complex mechanical response. It arises from the tissue's structure--a cluster of a very large number of closely packed airsacks (alveoli) and air ducts. Each of the alveoli has a shape of irregular polyhedron. It is bounded by the alveolar wall membrane. In the present study, a stochastic approach to the tissue's structure will be employed. The density distribution function of the membrane's orientation in space is considered as the predominant structural parameter. Based on this model the present theory relates the behavior of both the alveolar membrane and that of its liquid interface to the tissue's general constitutive properties. The resulting equations allow for anisotropic and visco-elastic effects. A protocol for material characterization along the present model is proposed as well. The methodology of the present theory is quite general and can be similarly used with other structural models of the lung tissue (e.g., models in which the effect of the alveolar ducts is included).     

Cellular Automata Modeling of Pulmonary Inflammation

Better understanding of the acute/chronic inflammation in airways is very important in order to avoid lung injuries for patients undergoing mechanical ventilation for treatment of respiratory problems. Local lung inflammation is triggered by many mechanisms within the lung, including pathogens. In this study, a cellular automata based model (CA) for pulmonary inflammation that incorporates biophysical processes during inflammatory responses was developed. The developed CA results in three possible outcomes related to homeostasis (healing), persistent infection, and resolved infection with high inflammation (inflamed state). The results from the model are validated qualitatively against other existing computational models. A sensitivity analysis was conducted on the model parameters and the outcomes were assessed. Overall, the model results showed possible outcomes that have been seen in clinical practice and animal models. The present model can be extended to include inflammation resulting from damage tissue and eventually to model inflammation resulting from acute lung injury and multiple organ dysfunction syndromes in critical illness and injury.     

Increased levels of a unique post-translationally modified betaIVb-tubulin isotype in liver cancer

Identifying changes at the molecular level during the development of hepatocellular carcinoma is important for the detection and treatment of the disease. The characteristic structural reorganization of preneoplastic cells may involve changes in the microtubule cytoskeleton. Microtubules are dynamic protein polymers that play an essential role in cell division, maintenance of cell shape, vesicle transport, and motility. They are comprised of multiple isotypes of alpha- and beta-tubulin. Changes in the levels of these isotypes may affect not only microtubule stability and sensitivity to drugs but also interactions with endogenous proteins. We employed a rat liver cancer model that progresses through stages similar to those of human liver cancer, including metastasis to the lung, to identify changes in the tubulin cytoskeleton during carcinogenesis. Tubulin isotypes in both liver and lung tissue were purified and subsequently separated by isoelectric focusing electrophoresis. The C-terminal isotype-defining region from each tubulin was obtained by cyanogen bromide cleavage and identified by mass spectrometry. A novel post-translational modification of betaIVb-tubulin in which two hydrophobic residues are proteolyzed from the C-terminus, thus exposing a charged glutamic acid residue, was identified. The unique form of betaIVb-tubulin was quantified in the liver tissue of all carcinoma stages and found to be approximately 3-fold more abundant in nodular and tumor tissue than in control tissue. The level of this form was also found to be increased in lung tissue with liver metastasis. This modification alters the C-terminal domain of one of the most abundant beta-tubulin isotypes in the liver and therefore may affect the interactions of microtubules with endogenous proteins.     

Measuring the lung function in the mouse: the challenge of size

Measurement of the effects of drugs, mediators and infectious agents on various models of lung disease, as well as assessment of lung function in the intact mouse has the potential for significantly advancing our knowledge of lung disease. However, the small size of the mouse presents significant challenges for the assessment of lung function. Because of compromises made between precision and noninvasiveness, data obtained may have an uncertain bearing on the mechanical response of the lung. Nevertheless, considerable recent progress has been made in developing valid and useful measures of mouse lung function. These advances, resulting in our current ability to measure sophisticated indices of lung function in laboratory animals, are likely to lead to important insights into the mechanisms of lung disease.     

单基因和双基因联合治疗对小鼠B16-F10黑色素瘤生长抑制作用研究

目的研究阳离子脂质体介导mGM-csf和mFlt-kdr3基因治疗以及2个基因联合治疗对小鼠B16-F10黑色素瘤肺转移以及实体瘤的生长抑制作用。方法通过尾静脉注射法和皮下注射法分别将10⁵个以及10⁶个对数生长期黑色素瘤细胞注入BALB/c小鼠体内,构建小鼠肺转移模型和腋下实体瘤模型。将2组模型小鼠分别分成5组:mFlt-kdr3治疗组、mGM-csf治疗组、联合治疗组(1次mFlt-kdr3,2次mGM-csf)、H1299脂质体质粒对照组和生理盐水对照组。肺转移模型小鼠建模3周后,尾静脉给药治疗,每次给药80μL,每次间隔1 d,共3次。完成后3 d,解剖取出小鼠肺组织并对肿瘤灶进行计数、苏木精-伊红染色。实体瘤模型小鼠在建模1周后开始瘤体穿刺给药,每次给药25μL,每次间隔1 d,共9次,每次给药前用游标卡尺测量瘤体的长、短径。结果肺转移治疗实验中,治疗组平均肿瘤个数显著少于对照组(P<0.05),且联合治疗组肿瘤个数最少,并且肺部结构完整,基本未见明显的肿瘤灶,可以看到明显的肺泡结构。实体瘤模型实验中,治疗组瘤体平均体积显著小...     

Lung tissue engineering: An update

Pulmonary disease is a worldwide public health problem that reduces the life quality and increases the need for hospital admissions as well as the risk of premature death. A common problem is the significant shortage of lungs for transplantation as well as patients must also take immunosuppressive drugs for the rest of their lives to keep the immune system from attacking transplanted organs. Recently, a new strategy has been proposed in the cellular engineering of lung tissue as decellularization approaches. The main components for the lung tissue engineering are: (1) A suitable biological or synthetic three-dimensional (3D) scaffold, (2) source of stem cells or cells, (3) growth factors required to drive cell differentiation and proliferation, and (4) bioreactor, a system that supports a 3D composite biologically active. Although a number of synthetic as well biological 3D scaffold suggested for lung tissue engineering, the current favorite scaffold is decellularized extracellular matrix scaffold. There are a large number of commercial and academic made bioreactors, the favor has been, the one easy to sterilize, physiologically stimuli and support active cell growth as well as clinically translational. The challenges would be to develop a functional lung will depend on the endothelialized microvascular network and alveolar–capillary surface area to exchange gas. A critical review of the each components of lung tissue engineering is presented, following an appraisal of the literature in the last 5 years. This is a multibillion dollar industry and consider unmet clinical need.     

A mathematical model of tumor growth. III. comparison with experiment

In this paper a model of nonuniform inhibitor production is used to discuss some experimental results obtained by Folkman and Hochberg for multicellular spheroids (of V-79 Chinese hamster lung tissue). Built into the mathematical model is a parameter b which is a measure of the degree of nonuniformity of the inhibitor production rate. The “inverse problem” is solved by finding the value of b necessary to account for results with which the uniform model is incompatible [6]. The resulting value of b enables a good estimate to be made for the observed width of peripheral mitotic zones in the V-79 spheroids, and the resulting stability parameters lie in appropriate ranges for the model to be a significant improvement over uniform models. Further improvements are discussed, including a heuristic model for estimating the destabilizing effect of vascularization on tissue growth.     

Pulmonary arterial hypertension: an update

Pulmonary arterial hypertension (PAH), defined as group 1 of the World Heart Organisation (WHO) classification of pulmonary hypertension, is an uncommon disorder of the pulmonary vascular system. It is characterised by an increased pulmonary artery pressure, increased pulmonary vascular resistance and specific histological changes. It is a progressive disease finally resulting in right heart failure and premature death. Typical symptoms are dyspnoea at exercise, chest pain and syncope; furthermore clinical signs of right heart failure develop with disease progression. Echocardiography is the key investigation when pulmonary hypertension is suspected, but a reliable diagnosis of PAH and associated conditions requires an intense work-up including invasive measurement by right heart catheterisation. Treatment includes general measures and drugs targeting the pulmonary artery tone and vascular remodelling. This advanced medical therapy has significantly improved morbidity and mortality in patients with PAH in the last decade. Combinations of these drugs are indicated when treatment goals of disease stabilisation are not met. In patients refractory to medical therapy lung transplantation should be considered an option.     

The nature of unbalanced cell growth caused by cytotoxic agents

The volume of cells grown in tissue culture following exposure to a wide variety of cytotoxic drugs or x-rays increases at a rate of 1 to 10% of cell mass per hour. The same phenomenon is seen in animal neoplasias and human leukemias. This increase in cell volume is the result of unbalanced cell growth with a resulting disproportionate synthesis of proteins and possibly other macromolecules in the cytoplasm and nucleus. The dose response curve for a decrease in cell survival as measured by cloning efficiency in tissue culture is quantitatively correlated with the dose response curve for inducing an increase in cell volume. This quantitative relationship makes feasible the use of the phenomenon of unbalanced cell growth as a measure of cell death in screening for cytotoxic drugs or in monitoring response to therapy. An hypothesis to explain this increase in cell volume following chemotherapy is that cells are by the action of these drugs induced into an abortive or unbalanced pseudo-cycle which is characterized by synthesis of substantial amounts of protein without other preparative steps for cell division.     

Axitinib Improves Radiotherapy in Murine Xenograft Lung Tumors

A third of patients with non-small cell lung cancer (NSCLC) present with un-resectable stage III locally advanced disease and are currently treated by chemo-radiotherapy but the median survival is only about 21 months. Using an orthotopic xenograft model of lung carcinoma, we have investigated the combination of radiotherapy with the anti-angiogenic drug axitinib (AG-013736, Pfizer), which is a small molecule receptor tyrosine kinase inhibitor that selectively targets the signal transduction induced by VEGF binding to VEGFR receptors. We have tested the combination of axitinib with radiotherapy in nude mice bearing human NSCLC A549 lung tumors. The therapy effect was quantitatively evaluated in lung tumor nodules. The modulation of radiation-induced pneumonitis, vascular damage and fibrosis by axitinib was assessed in lung tissue. Lung irradiation combined with long-term axitinib treatment was safe resulting in minimal weight loss and no vascular injury in heart, liver and kidney tissues. A significant decrease in the size of lung tumor nodules was observed with either axitinib or radiation, associated with a decrease in Ki-67 staining and a heavy infiltration of inflammatory cells in tumor nodules. The lungs of mice treated with radiation and axitinib showed a complete response with no detectable residual tumor nodules. A decrease in pneumonitis, vascular damage and fibrosis were observed in lung tissues from mice treated with radiation and axitinib. Our studies suggest that axitinib is a potent and safe drug to use in conjunction with radiotherapy for lung cancer that could also act as a radioprotector for lung tissue by reducing pneumonitis and fibrosis.     

Wild Type Mesenchymal Cells Contribute to the Lung Pathology of Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare disease leading to lungs cysts and progressive respiratory failure. Cells of unknown origin accumulate in the lungs forming nodules and eventually resulting in lung cysts. These LAM cells are described as clonal with bi-allelic mutations in TSC-2 resulting in constitutive mTOR activation. However LAM nodules are heterogeneous structures containing cells of different phenotypes; we investigated whether recruited wild type cells were also present alongside mutation bearing cells. Cells were isolated from LAM lung tissue, cultured and characterised using microscopy, immunocytochemistry and western blotting. Fibroblast-like cells were identified in lung tissue using immunohistochemical markers. Fibroblast chemotaxis toward LAM cells was examined using migration assays and 3D cell culture. Fibroblast-like cells were obtained from LAM lungs: these cells had fibroblast-like morphology, actin stress fibres, full length tuberin protein and suppressible ribosomal protein S6 activity suggesting functional TSC-1/2 protein. Fibroblast Activation Protein, Fibroblast Specific Protein/S100A4 and Fibroblast Surface Protein all stained subsets of cells within LAM nodules from multiple donors. In a mouse model of LAM, tuberin positive host derived cells were also present within lung nodules of xenografted TSC-2 null cells. In vitro, LAM 621-101 cells and fibroblasts formed spontaneous aggregates over three days in 3D co-cultures. Fibroblast chemotaxis was enhanced two fold by LAM 621-101 conditioned medium (p=0.05), which was partially dependent upon LAM cell derived CXCL12. Further, LAM cell conditioned medium also halved fibroblast apoptosis under serum free conditions (p=0.03). Our findings suggest that LAM nodules contain a significant population of fibroblast-like cells. Analogous to cancer associated fibroblasts, these cells may provide a permissive environment for LAM cell growth and contribute to the lung pathology of LAM lung disease.     

Identification of new candidate drugs for lung cancer using chemical–chemical interactions,chemical–protein interactions and a K-means clustering algorithm

Lung cancer, characterized by uncontrolled cell growth in the lung tissue, is the leading cause of global cancer deaths. Until now, effective treatment of this disease is limited. Many synthetic compounds have emerged with the advancement of combinatorial chemistry. Identification of effective lung cancer candidate drug compounds among them is a great challenge. Thus, it is necessary to build effective computational methods that can assist us in selecting for potential lung cancer drug compounds. In this study, a computational method was proposed to tackle this problem. The chemical–chemical interactions and chemical–protein interactions were utilized to select candidate drug compounds that have close associations with approved lung cancer drugs and lung cancer-related genes. A permutation test and K-means clustering algorithm were employed to exclude candidate drugs with low possibilities to treat lung cancer. The final analysis suggests that the remaining drug compounds have potential anti-lung cancer activities and most of them have structural dissimilarity with approved drugs for lung cancer.     

Pharmacokinetic and toxicity profile of a phosphorothioate oligonucleotide following inhalation delivery to lung in mice

Antisense oligonucleotides are currently being investigated for the treatment of a variety of diseases. Antisense drugs are being administered primarily by parenteral injection. To explore more convenient patient delivery methods, we have characterized the tissue kinetics and tolerability of an inhaled aerosol formulation of a phosphorothioate oligonucleotide in mice. Concentrations of oligonucleotide in bronchioalveolar lavage fluid, plasma, and tissue and immunohistochemical localization were used to assess deposition and pharmacokinetic parameters. Significant concentrations of oligonucleotide in lung, as well as systemic tissues, were measured following a pulmonary dose of 12 mg/kg. Doses as low as 1-3 mg/kg also produced significant concentrations of oligonucleotide (>50 microg oligonucleotide per gram of tissue), and these were maintained in the lung with a halflife of 20 hours or greater. Oligonucleotide was localized to bronchiolar epithelium and alveolar epithelium and endothelium. Toxicity was mild at the 12 mg/kg level and minimal to absent at doses of 3 mg/kg or below. Based on a favorable pharmacokinetic profile and a relative lack of toxicity, inhalation delivery appears to be a therapeutic option for antisense oligonucleotides.     

A mathematical model of pulmonary gas exchange under inflammatory stress

During a severe local or systemic inflammatory response, immune mediators target lung tissue. This process may lead to acute lung injury and impaired diffusion of gas molecules. Although several mathematical models of gas exchange have been described, none simulate acute lung injury following inflammatory stress. In view of recent laboratory and clinical progress in the understanding of the pathophysiology of acute lung injury, such a mathematical model would be useful. We first derived a partial differential equations model of gas exchange on a small physiological unit of the lung (≈25 alveoli), which we refer to as a respiratory unit (RU). We next developed a simple model of the acute inflammatory response and implemented its effects within a RU, creating a single RU model. Linking multiple RUs with various ventilation/perfusion ratios and taking into account pulmonary venous blood remixing yielded our lung-scale model. Using the lung-scale model, we explored the predicted effects of inflammation on ventilation/perfusion distribution and the resulting pulmonary venous partial pressure oxygen level during systemic inflammatory stresses. This model represents a first step towards the development of anatomically faithful models of gas exchange and ventilation under a broad range of local and systemic inflammatory stimuli resulting in acute lung injury, such as infection and mechanical strain of lung tissue.     

Novel mass spectrometry imaging software assisting labeled normalization and quantitation of drugs and neuropeptides directly in tissue sections

MALDI MS imaging has been extensively used to produce qualitative distribution maps of proteins, peptides, lipids, small molecule pharmaceuticals and their metabolites directly in biological tissue sections. There is growing demand to quantify the amount of target compounds in the tissue sections of different organs. We present a novel MS imaging software including protocol for the quantitation of drugs, and for the first time, an endogenous neuropeptide directly in tissue sections. After selecting regions of interest on the tissue section, data is read and processed by the software using several available methods for baseline corrections, subtractions, denoising, smoothing, recalibration and normalization. The concentrations of in vivo administered drugs or endogenous compounds are then determined semi-automatically using either external standard curves, or by using labeled compounds, i.e., isotope labeled analogs as standards. As model systems, we have quantified the distribution of imipramine and tiotropium in the brain and lung of dosed rats. Substance P was quantified in different mouse brain structures, which correlated well with previously reported peptide levels. Our approach facilitates quantitative data processing and labeled standards provide better reproducibility and may be considered as an efficient tool to quantify drugs and endogenous compounds in tissue regions of interest.