Deriving respiratory cell types from stem cells

The reported pluripotential capabilities of many human stem cell types has made them an attractive area of research, given the belief they may hold considerable therapeutic potential for treating a wide range of human diseases and injuries. Although the bulk of stem cell based research has focused on developing procedures for the treatment of pancreatic, neural, cardiovascular and haematopoietic diseases, the potential for deriving respiratory cell types from stem cells for treatment of respiratory specific diseases has also been explored. It is suggested that stem cell derivatives may be used for lung replacement/regeneration therapeutics and high though-put pharmacological screening strategies for a variety of respiratory injuries and diseases including: cystic fibrosis, chronic obstructive pulmonary disease, respiratory distress syndrome, pulmonary fibrosis and pulmonary edema. This review will explore recent progress in characterizing adult respiratory and bone marrow derived stem cells with respiratory potential as well as the endogenous mechanisms directing the homing of these cells to the diseased and injured lung. In addition, the potential for embryonic stem cell based therapies in this domain as well as the histological, anatomical and molecular aspects of respiratory development will be summarized.     

Animal models for gastric Helicobacter immunology and vaccine studies

Over the last decade animal models have been used extensively to investigate disease processes and therapy for Helicobacter pylori infections. The H. pylori animal models which have been used in pathogenesis and vaccine studies include the gnotobiotic pig, non-human primates, cats, dogs, and several species of rodents including mice, rats, gerbils and guinea pigs. H. felis infection of mice and H. mustelae infection of ferrets have also been used. Recently, investigators have begun using transgenic mice and gene-targeted 'knock-out' mice to investigate Helicobacter infections. Each of these animal models has distinct advantages and disadvantages which are discussed in this minireview. The choice of an animal model is dictated by factors such as cost and an understanding of how each model will or will not allow fulfillment of experimental objectives.     

Executionary pathway for apoptosis：lessons from mutant mice

Apoptosis or programmed cell death(PCD) is an evolutionarily conserved cellular process that is essential for normal development and homeostasis of multicellular organisms.Defects in the apoptosis signaling result in many diseases including autoimmune diseases and cancer.The apoptosis signaling pathway was first described genetically in the nematode Caenorhabditis elegans which serves as a framework for the more complex apoptotic pathways that exist in mammals.In this review,we will discuss the apoptotic pathways that are emerging in mammals as elucidated by studies of gene-targeted mutant mice.     

TLR2 signaling is critical for Mycoplasma pneumoniae-induced airway mucin expression

Excessive airway mucin production contributes to airway obstruction in lung diseases such as asthma and chronic obstructive pulmonary disease. Respiratory infections, such as atypical bacterium Mycoplasma pneumoniae (Mp), have been proposed to worsen asthma and chronic obstructive pulmonary disease in part through increasing mucin. However, the molecular mechanisms involved in infection-induced airway mucin overexpression remain to be determined. TLRs have been recently shown to be a critical component in host innate immune response to infections. TLR2 signaling has been proposed to be involved in inflammatory cell activation by mycoplasma-derived lipoproteins. In this study, we show that TLR2 signaling is critical in Mp-induced airway mucin expression in mice and human lung epithelial cells. Respiratory Mp infection in BALB/c mice activated TLR2 signaling and increased airway mucin. A TLR2-neutralizing Ab significantly reduced mucin expression in Mp-infected BALB/c mice. Furthermore, Mp-induced airway mucin was abolished in TLR2 gene-deficient C57BL/6 mice. Additionally, Mp was shown to increase human lung A549 epithelial cell mucin expression, which was inhibited by the overexpression of a human TLR2 dominant-negative mutant. These results clearly demonstrate that respiratory Mp infection increases airway mucin expression, which is dependent on the activation of TLR2 signaling.     

Alveolus formation: what have we learned from genetic studies?

The respiratory system has two basic functions: air exchange and pathogen clearance. The conducting airway and alveolar parenchyma are the basic structures to fulfill these functions during respiratory cycles. In humans, there are approximately 40 cell types in the lung that coordinately work together through various structural and signaling molecules. These molecules are vital for maintaining normal lung functions in response to environmental changes. Aberrant expression of these molecules can jeopardize human health and cause various pulmonary diseases. In this article, we will review some recent progress made in the pulmonary field, using genetic animal model systems to elucidate molecular mechanisms that are important for alveolar formation and lung diseases.     

Stimulator of interferon genes (STING): A “new chapter” in virus-associated cancer research. Lessons from wild-derived mouse models of innate immunity

Thanks to the numerous studies that have been carried out recently in the field of cytosolic DNA sensing, STING (Stimulator of Interferon Genes) is now recognized as a key mediator of innate immune signaling. A substantial body of evidence derived from in vivo mouse models demonstrates that STING-regulated pathways underlie the pathogenesis of many diseases including infectious diseases and cancers. It has also become evident from these studies that STING is a promising therapeutic target for the treatment of cancer. However, mouse strains commonly used for modelling innate immune response against infections or tumors do not allow investigators to accurately reproduce certain specific characteristics of immune response observed in human cells. In this review, we will discuss recent data demonstrating that the use of wild-derived genetically distinct inbred mice as a model for investigation into the innate immunity signaling networks may provide valuable insight into the STING-regulated pathways specific for human cells. The maximum complexity of STING-mediated mechanisms can probably be seen in case of DNA virus-induced carcinogenesis in which STING may perform unexpected biological activities. Therefore, in another part of this review we will summarize emerging data on the role of STING in human DNA virus-related oncopathologies, with particular attention to HPV-associated cervical cancer, aiming to demonstrate that STING indeed “starts a new chapter” in research on this issue and that wild-derived mouse models of STING-mediated response to infections will probably be helpful in finding out molecular basis for clinical observations.     

Noninvasive Intratracheal Intubation to Study the Pathology and Physiology of Mouse Lung

The use of a model that mimics the condition of lung diseases in humans is critical for studying the pathophysiology and/or etiology of a particular disease and for developing therapeutic intervention. With the increasing availability of knockout and transgenic derivatives, together with a vast amount of genetic information, mice provide one of the best models to study the molecular mechanisms underlying the pathology and physiology of lung diseases. Inhalation, intranasal instillation, intratracheal instillation, and intratracheal intubation are the most widely used techniques by a number of investigators to administer materials of interest to mouse lungs. There are pros and cons for each technique depending on the goals of a study. Here a noninvasive intratracheal intubation method that can directly deliver exogenous materials to mouse lungs is presented. This technique was applied to administer bleomycin to mouse lungs as a model to study pulmonary fibrosis.     

Pressure Controlled Ventilation to Induce Acute Lung Injury in Mice

Murine models are extensively used to investigate acute injuries of different organs systems (1-34). Acute lung injury (ALI), which occurs with prolonged mechanical ventilation, contributes to morbidity and mortality of critical illness, and studies on novel genetic or pharmacological targets are areas of intense investigation (1-3, 5, 8, 26, 30, 33-36). ALI is defined by the acute onset of the disease, which leads to non-cardiac pulmonary edema and subsequent impairment of pulmonary gas exchange (36). We have developed a murine model of ALI by using a pressure-controlled ventilation to induce ventilator-induced lung injury (2). For this purpose, C57BL/6 mice are anesthetized and a tracheotomy is performed followed by induction of ALI via mechanical ventilation. Mice are ventilated in a pressure-controlled setting with an inspiratory peak pressure of 45 mbar over 1 - 3 hours. As outcome parameters, pulmonary edema (wet-to-dry ratio), bronchoalveolar fluid albumin content, bronchoalveolar fluid and pulmonary tissue myeloperoxidase content and pulmonary gas exchange are assessed (2). Using this technique we could show that it sufficiently induces acute lung inflammation and can distinguish between different treatment groups or genotypes (1-3, 5). Therefore this technique may be helpful for researchers who pursue molecular mechanisms involved in ALI using a genetic approach in mice with gene-targeted deletion.     

Paving the road for lung stem cell biology: bronchioalveolar stem cells and other putative distal lung stem cells

New discoveries in stem cell biology are making the biology of solid tissues increasingly complex. Important seminal studies demonstrating the presence of damage-resistant cell populations together with new isolation and characterization techniques suggest that stem cells exist in the adult lung. More detailed in vivo molecular and cellular characterization of bronchioalveolar stem cells (BASCs), other putative lung stem and progenitor cells, and differentiated cells is needed to determine the lineage relationships in adult lung. Lung diseases such as cystic fibrosis or chronic obstructive pulmonary disease, as well as the most common form of lung cancer in the United States, all involve apparent bronchiolar and alveolar cell defects. It is likely that the delicate balance of stem, progenitor, and differentiated cell functions in the lung is critically affected in patients with these devastating diseases. Thus the discovery of BASCs and other putative lung stem cells will lay the foundation for new inroads to understanding lung biology related to lung disease.     

Heparan sulfate in lung morphogenesis: The elephant in the room

Heparan sulfate (HS) is a structurally complex polysaccharide located on the cell surface and in the extracellular matrix, where it participates in numerous biological processes through interactions with a vast number of regulatory proteins such as growth factors and morphogens. HS is crucial for lung development; disruption of HS synthesis in flies and mice results in a major aberration of airway branching, and in mice, it results in neonatal death as a consequence of malformed lungs and respiratory distress. Epithelial–mesenchymal interactions governing lung morphogenesis are directed by various diffusible proteins, many of which bind to, and are regulated by HS, including fibroblast growth factors, sonic hedgehog, and bone morphogenetic proteins. The majority of research into the molecular mechanisms underlying defective lung morphogenesis and pulmonary pathologies, such as bronchopulmonary dysplasia and pulmonary hypoplasia associated with congenital diaphragmatic hernia (CDH), has focused on abnormal protein expression. The potential contribution of HS to abnormalities of lung development has yet to be explored to any significant extent, which is somewhat surprising given the abnormal lung phenotype exhibited by mutant mice synthesizing abnormal HS. This review summarizes our current understanding of the role of HS and HS‐binding proteins in lung morphogenesis and will present in vitro and in vivo evidence for the fundamental importance of HS in airway development. Finally, we will discuss the future possibility of HS‐based therapeutics for ameliorating insufficient lung growth associated with lung diseases such as CDH. Birth Defects Research (Part C) 90:32–44, 2010. © 2010 Wiley‐Liss, Inc.     

Mechanisms involved in lung cancer development in COPD

Lung cancer and chronic obstructive pulmonary disease (COPD) are leading causes of morbidity and mortality worldwide. They share a common environmental risk factor in cigarette smoke exposure and a genetic predisposition represented by the incidence of these diseases in only a fraction of smokers. COPD is also a major independent risk factor for lung carcinoma, among long-term smokers. Smokers with COPD also have a higher risk of developing a specific histological subtype of non-small cell lung cancer termed squamous cell carcinoma. For these reasons the focus of this review is on the potential pathogenic molecular links between tobacco smoking-related COPD and squamous cell carcinoma. We believe that we need to promote more studies on the molecular and cellular pathobiology of smokers with premalignant bronchial lesions of the squamous cell lung carcinoma compared with a control group of smokers with and without COPD to unravel the complex molecular interactions between COPD and early squamous cell lung carcinoma. These studies should also look at younger healthy smokers in combination with risk models of lung cancer and COPD. Overall these studies may allow the discovery of new molecular targets of the early carcinogenesis process that in the foreseeable future may render the early diagnosis and treatment, and may be even the prevention, of invasive squamous cell lung carcinoma a reality.     

抗肺纤维化药物治疗研究进展

特发性肺纤维化是严重危害生命的间质性肺疾病,诊断后半数生存率仅为3年,超过大部分恶性肿瘤.目前所有的抗肺纤维化治疗措施疗效甚微.随着对肺纤维化发病分子细胞机制研究的不断深入,已经发现并确认多种抗肺纤维化的新药靶.本文首先概述抗肺纤维化疾病的临床治疗现状、正在临床实验的新药物,然后重点介绍作用于肺泡上皮细胞、成肌纤维细胞或具有抑制血管新生、调节Th1/Th2细胞因子平衡、阻断氧化应激等作用药物治疗肺纤维化疾病的前景.     

Cre-loxP mediated control of PrP to study transmissible spongiform encephalopathy diseases

Expression of the PrP glycoprotein is essential for the development of the transmissible spongiform encephalopathy (TSE) or prion diseases. Although PrP is widely expressed in the mouse, the precise relevance of different PrP-expressing cell types to disease remains unclear. To address this, we generated two lines of floxed PrP gene-targeted transgenic mice using the Cre recombinase-loxP system. These floxed mice allow a functional PrP allele to be either switched "on" or "off." We demonstrate control of PrP expression for both alleles following Cre-mediated recombination, as determined by PrP mRNA and protein expression in the brain. Moreover, we show that Cre-mediated alteration of PrP expression in these mice has a major influence on the development of TSE disease. These floxed PrP mice will allow the involvement of PrP expression in specific cell types following TSE infection to be defined, which may identify potential sites for therapeutic intervention.     

The genetic and molecular mechanisms of motor neuron disease

Significant progress has been made in the identification of genes and chromosomal loci associated with several types of motor neuron disease. Of particular interest is recent work on the pathogenic mechanisms underlying these diseases, especially studies in in vitro model systems and in transgenic and gene-targeted mice.     

The role of osteopontin in lung disease

Osteopontin (Opn) is a multifunctional protein independently discovered by investigators from diverse scientific backgrounds and implicated in a broad array of pathological processes. Opn exists both intra- and extracellularly and in numerous pre- and post-translational isoforms. Structurally Opn resembles a matrix protein yet it has well-characterized cytokine like properties including the regulation of cellular migration and cell-mediated immunity. It has thus been classified as both a matricellular protein and a cytokine. Opn is among the most abundantly expressed proteins in a range of lung diseases and has been shown to regulate aspects of pulmonary granuloma formation, fibrosis, and malignancy. Future studies will explore the diagnostic and therapeutic potential of modulating the function of Opn in vivo.     

自噬及其在肺部疾病中作用研究进展

自噬作为一种新的细胞程序化死亡方式,在维持细胞内环境稳态中起着重要作用。它由溶酶体介导,对细胞内衰老细胞器或受损蛋白质进行再次利用,以补充细胞在"饥饿"状态下的物质供给。自噬曾被认为是细胞对氧化应激的随机自我保护性反应,然而最近研究发现自噬体的形成具有选择性和高度保守性的特点。目前研究发现自噬在COPD、肺气肿、肺纤维化、肺动脉高压、急性肺损伤、肺肿瘤等肺部疾病中起重要作用。本文通过分析总结自噬信号传导机制及其在肺部疾病中的相关作用,以阐明肺部疾病的可能发生机制,从而指导相关疾病的临床治疗。     

Airway imaging in disease: Gimmick or useful tool?

Airway remodeling is an important pathophysiological mechanism in a variety of chronic airway diseases. Historically investigators have had to use invasive techniques such as histological examination of excised tissue to study airway wall structure. The last several years has seen a proliferation of relatively noninvasive techniques to assess the airway branching pattern, wall thickness, and more recently, airway wall tissue components. These methods include computed tomography, magnetic resonance imaging, and optical coherence tomography. These new imaging technologies have become popular because to understand the physiology of lung disease it is important we understand the underlying anatomy. However, these new approaches are not standardized or available in all centers so a review of their validity and clinical utility is appropriate. This review documents how investigators are working hard to correct for inconsistencies between techniques so that they become more accepted and utilized in clinical settings. These new imaging techniques are very likely to play a frontline role in the study of lung disease and will, hopefully, allow clinicians and investigators to better understand disease pathogenesis and to design and assess new therapeutic interventions.     

Stem cell therapy for COVID-19 and other respiratory diseases: Global trends of clinical trials

Respiratory diseases, including coronavirus disease 2019 and chronic obstructive pulmonary disease (COPD), are leading causes of global fatality. There are no effective and curative treatments, but supportive care only. Cell therapy is a promising therapeutic strategy for refractory and unmanageable pulmonary illnesses, as proved by accumulating preclinical studies. Stem cells consist of totipotent, pluripotent, multipotent, and unipotent cells with the potential to differentiate into cell types requested for repair. Mesenchymal stromal cells, endothelial progenitor cells, peripheral blood stem cells, and lung progenitor cells have been applied to clinical trials. To date, the safety and feasibility of stem cell and extracellular vesicles administration have been confirmed by numerous phase I/II trials in patients with COPD, acute respiratory distress syndrome, bronchial dysplasia, idiopathic pulmonary fibrosis, pulmonary artery hypertension, and silicosis. Five routes and a series of doses have been tested for tolerance and advantages of different regimes. In this review, we systematically summarize the global trends for the cell therapy of common airway and lung diseases registered for clinical trials. The future directions for both new clinical trials and preclinical studies are discussed.     

自噬与肺部疾病研究进展

自噬(autophagy)是广泛存在于真核细胞中的基本生命现象,是细胞适应环境变化、防御病原微生物侵袭、维持内环境稳定的重要机制．多种肺部疾病中存在自噬活性的变化,自噬与肺部疾病的发生、发展密切相关．自噬在慢性阻塞性肺病、肺气肿、肺癌、肺结核等许多肺部疾病中发生,且发挥重要作用．现从自噬与多种肺部疾病的关系角度进行综述,有助于了解自噬在肺部疾病中发挥的作用,以便进一步研究自噬的调节,为肺部疾病的治疗提供新思路．