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Concept: Human lung


Background The prevalence of pulmonary embolism among patients hospitalized for syncope is not well documented, and current guidelines pay little attention to a diagnostic workup for pulmonary embolism in these patients. Methods We performed a systematic workup for pulmonary embolism in patients admitted to 11 hospitals in Italy for a first episode of syncope, regardless of whether there were alternative explanations for the syncope. The diagnosis of pulmonary embolism was ruled out in patients who had a low pretest clinical probability, which was defined according to the Wells score, in combination with a negative d-dimer assay. In all other patients, computed tomographic pulmonary angiography or ventilation-perfusion lung scanning was performed. Results A total of 560 patients (mean age, 76 years) were included in the study. A diagnosis of pulmonary embolism was ruled out in 330 of the 560 patients (58.9%) on the basis of the combination of a low pretest clinical probability of pulmonary embolism and negative d-dimer assay. Among the remaining 230 patients, pulmonary embolism was identified in 97 (42.2%). In the entire cohort, the prevalence of pulmonary embolism was 17.3% (95% confidence interval, 14.2 to 20.5). Evidence of an embolus in a main pulmonary or lobar artery or evidence of perfusion defects larger than 25% of the total area of both lungs was found in 61 patients. Pulmonary embolism was identified in 45 of the 355 patients (12.7%) who had an alternative explanation for syncope and in 52 of the 205 patients (25.4%) who did not. Conclusions Pulmonary embolism was identified in nearly one of every six patients hospitalized for a first episode of syncope. (Funded by the University of Padua; PESIT number, NCT01797289 .).

Concepts: Clinical trial, Lung, Hospital, Heart, Pulmonary embolism, Pulmonary artery, Human lung, Embolism


Didecyldimethylammonium chloride (DDAC) is a representative dialkyl-quaternary ammonium compound that is used as a disinfectant against several pathogens and is also used in commercial, industrial, and residential settings. We previously investigated toxicity on air way system following single instillation of DDAC to the lungs in mice, and found that DDAC causes pulmonary injury, which is associated with altered antioxidant antimicrobial responses; the inflammatory phase is accompanied or followed by fibrotic response. The present study was conducted to monitor transforming growth factor-β (TGF-β) signaling in pulmonary fibrosis induced by DDAC. Mice were intratracheally instilled with DDAC and sacrificed 1, 3, or 7 days after treatment to measure TGF-β signaling. In order to further evaluate TGF-β signaling, we treated isolated mouse lung fibroblasts with DDAC. Fibrotic foci were observed in the lungs on day 3, and were widely extended on day 7, with evidence of increased α-smooth muscle actin-positive mesenchymal cells and upregulation of Type I procollagen mRNA. Developing fibrotic foci were likely associated with increased expression of Tgf-β1 mRNA, in addition to decreased expression of Bone morphogenetic protein-7 mRNA. In fibrotic lung samples, the expression of phosphorylated SMAD2/3 was considerably higher than that of phosphorylated SMAD1/5. In isolated lung fibroblasts, the mRNA levels of Tgf-β1 were specifically increased by DDAC treatment, which prolonged phosphorylation of SMAD2/3. These effects were abolished by treatment with SD208 - a TGF-βRI kinase inhibitor. The results suggest that DDAC induces pulmonary fibrosis in association with TGF-β signaling.

Concepts: Lung, Pneumonia, Fibrosis, Heart, Pulmonary contusion, Idiopathic pulmonary fibrosis, Pneumothorax, Human lung


Tissue-specific differentiation programs become dysregulated during cancer evolution. The transcription factor Nkx2-1 is a master regulator of pulmonary differentiation that is downregulated in poorly differentiated lung adenocarcinoma. Here we use conditional murine genetics to determine how the identity of lung epithelial cells changes upon loss of their master cell-fate regulator. Nkx2-1 deletion in normal and neoplastic lungs causes not only loss of pulmonary identity but also conversion to a gastric lineage. Nkx2-1 is likely to maintain pulmonary identity by recruiting transcription factors Foxa1 and Foxa2 to lung-specific loci, thus preventing them from binding gastrointestinal targets. Nkx2-1-negative murine lung tumors mimic mucinous human lung adenocarcinomas, which express gastric markers. Loss of the gastrointestinal transcription factor Hnf4α leads to derepression of the embryonal proto-oncogene Hmga2 in Nkx2-1-negative tumors. These observations suggest that loss of both active and latent differentiation programs is required for tumors to reach a primitive, poorly differentiated state.

Concepts: DNA, Genetics, Gene expression, Lung, Lung cancer, Epithelium, Carcinoma, Human lung


The human lung tissue microbiota remains largely uncharacterized, although a number of studies based on airway samples suggest the existence of a viable human lung microbiota. Here we characterized the taxonomic and derived functional profiles of lung microbiota in 165 non-malignant lung tissue samples from cancer patients.

Concepts: Epidemiology, Cancer, Disease, Lung, Lung cancer, Human lung


Bioengineered lungs produced from patient-derived cells may one day provide an alternative to donor lungs for transplantation therapy. Here we report the regeneration of functional pulmonary vasculature by repopulating the vascular compartment of decellularized rat and human lung scaffolds with human cells, including endothelial and perivascular cells derived from induced pluripotent stem cells. We describe improved methods for delivering cells into the lung scaffold and for maturing newly formed endothelium through co-seeding of endothelial and perivascular cells and a two-phase culture protocol. Using these methods we achieved ∼75% endothelial coverage in the rat lung scaffold relative to that of native lung. The regenerated endothelium showed reduced vascular resistance and improved barrier function over the course of in vitro culture and remained patent for 3 days after orthotopic transplantation in rats. Finally, we scaled our approach to the human lung lobe and achieved efficient cell delivery, maintenance of cell viability and establishment of perfusable vascular lumens.

Concepts: Lung, Stem cell, Stem cells, Cell biology, Heart, Epithelium, Induced pluripotent stem cell, Human lung


Excessive host inflammatory responses negatively impact disease outcomes in respiratory infection. Host-pathogen interactions during the infective phase of influenza are well studied, but little is known about the host’s response during the repair stage. Here, we show that influenza infection stimulated the expression of angiopoietin-like 4 (ANGPTL4) via a direct IL6-STAT3-mediated mechanism. ANGPTL4 enhanced pulmonary tissue leakiness and exacerbated inflammation-induced lung damage. Treatment of infected mice with neutralizing anti-ANGPTL4 antibodies significantly accelerated lung recovery and improved lung tissue integrity. ANGPTL4-deficient mice also showed reduced lung damage and recovered faster from influenza infection when compared to their wild-type counterparts. Retrospective examination of human lung biopsy specimens from infection-induced pneumonia with tissue damage showed elevated expression of ANGPTL4 when compared to normal lung samples. These observations underscore the important role that ANGPTL4 plays in lung infection and damage and may facilitate future therapeutic strategies for the treatment of influenza pneumonia.

Concepts: Inflammation, Cancer, Pulmonology, Lung, Pneumonia, Transmission and infection of H5N1, Mucus, Human lung


Lung ageing, a significant risk factor for chronic human lung diseases such as COPD and emphysema, is characterised by airspace enlargement and decreasing lung function. Likewise, in prematurely ageing telomerase null (terc-/-) mice, p53 stabilisation within diminishing numbers of alveolar epithelial type 2 cells (AEC2) accompanies reduced lung function. Resveratrol (RSL) is a plant phytoalexin that has previously showed efficacy in enhancing invertebrate longevity and supporting mammalian muscle metabolism when delivered orally. Here, we tested whether inhaled RSL could protect young, terc-/- mice from accelerated ageing of the lung.

Concepts: Epidemiology, Enzyme, Pulmonology, Asthma, Lung, Chronic obstructive pulmonary disease, Emphysema, Human lung


The cellular and molecular mechanisms that underpin regeneration of the human lung are unknown and study of lung repair has been impeded by the necessity for reductionist models that may exclude key components. We hypothesized that multicellular epithelial and mesenchymal cell clusters or lung organoid units (LuOU) could be transplanted to recapitulate proximal and distal cellular structures of the native lung and airways. Transplantation of LuOU resulted in the growth of tissue-engineered lung (TELu) that contained the necessary cell types consistent with native adult lung tissue and demonstrated proliferative cells at 2 and 4 weeks. This technique recapitulated important elements of both mouse and human lungs featuring key components of both the proximal and distal lung regions. When LuOU were generated from whole lung, TELu contained key epithelial and mesenchymal cell types, and the origin of the cells was traced from both ActinGFP and SPCGFP donors to indicate that the cells in TELu derived from the transplanted LuOU. Alveolar epithelial type 2 cells (AEC2s), club cells, ciliated cells marked by beta-tubulin IV, alveolar epithelial type I cells, Sox-2 positive proximal airway progenitors, p63-positive basal cells, and CGRP-positive pulmonary neuroendocrine were identified in the TELu. The mesenchymal components of peribronchial smooth muscle and nerve were identified with a CD31-positive donor endothelial cell contribution to TELu vasculature. TELu successfully grew from postnatal tissues from whole murine and human lung, distal murine lung, as well as murine and human trachea. These data support a model of post-natal lung regeneration containing the diverse cell types present in the entirety of the respiratory tract.

Concepts: Cell, Lung, Organelle, Heart, Epithelium, Cellular differentiation, Vertebrate trachea, Human lung


The potent immunomodulatory cytokine interleukin (IL)-6 is consistently upregulated in human lungs with emphysema, and in mouse emphysema models; however, the mechanism(s) by which IL-6 promotes emphysema remains obscure. IL-6 signals using two distinct modes, classical signalling via its membrane-bound IL-6 receptor (mIL-6R), and trans-signalling via a naturally-occurring soluble IL-6R (sIL-6R).

Concepts: Lung, Signal, Emphysema, Human lung


IFN-γ-producing CD4 T cells are required for protection against Mycobacterium tuberculosis (Mtb) infection, but the extent to which IFN-γ contributes to overall CD4 T cell-mediated protection remains unclear. Furthermore, it is not known if increasing IFN-γ production by CD4 T cells is desirable in Mtb infection. Here we show that IFN-γ accounts for only ~30% of CD4 T cell-dependent cumulative bacterial control in the lungs over the first six weeks of infection, but >80% of control in the spleen. Moreover, increasing the IFN-γ-producing capacity of CD4 T cells by ~2 fold exacerbates lung infection and leads to the early death of the host, despite enhancing control in the spleen. In addition, we show that the inhibitory receptor PD-1 facilitates host resistance to Mtb by preventing the detrimental over-production of IFN-γ by CD4 T cells. Specifically, PD-1 suppressed the parenchymal accumulation of and pathogenic IFN-γ production by the CXCR3+KLRG1-CX3CR1- subset of lung-homing CD4 T cells that otherwise mediates control of Mtb infection. Therefore, the primary role for T cell-derived IFN-γ in Mtb infection is at extra-pulmonary sites, and the host-protective subset of CD4 T cells requires negative regulation of IFN-γ production by PD-1 to prevent lethal immune-mediated pathology.

Concepts: Immune system, Bacteria, Lung, Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Pneumothorax, Human lung