Airway hillocks are injury-resistant reservoirs of unique plastic stem cells.

Airway hillocks are stratified epithelial structures of unknown function1. Hillocks persist for months and have a unique population of basal stem cells that express genes associated with barrier function and cell adhesion. Hillock basal stem cells continually replenish overlying squamous barrier cells. They exhibit dramatically higher turnover than the abundant, largely quiescent classic pseudostratified airway epithelium. Hillocks resist a remarkably broad spectrum of injuries, including toxins, infection, acid and physical injury because hillock squamous cells shield underlying hillock basal stem cells from injury. Hillock basal stem cells are capable of massive clonal expansion that is sufficient to resurface denuded airway, and eventually regenerate normal airway epithelium with each of its six component cell types. Hillock basal stem cells preferentially stratify and keratinize in the setting of retinoic acid signalling inhibition, a known cause of squamous metaplasia2,3. Here we show that mouse hillock expansion is the cause of vitamin A deficiency-induced squamous metaplasia. Finally, we identify human hillocks whose basal stem cells generate functional squamous barrier structures in culture. The existence of hillocks reframes our understanding of airway epithelial regeneration. Furthermore, we show that hillocks are one origin of 'squamous metaplasia', which is long thought to be a precursor of lung cancer.

Nasal symptoms, epithelial injury and neurogenic inflammation in elite swimmers.

BACKGROUND: A high burden of lower airway symptoms is found in elite swimmers. To what extent elite swimmers suffer from upper airway symptoms and how these associate with nasal inflammation is less clear. We here aimed to evaluate upper airway symptoms and nasal inflammation in elite athletes. METHODOLOGY: Elite swimmers, indoor athletes and age-matched controls were recruited. Upper airway symptoms were assessed by sino-nasal outcome test (SNOT)-22 questionnaire. Visual Analogue score (VAS) for nasal symptoms as well as neurogenic and inflammatory mediators in nasal fluid were assessed at baseline, immediately and 24-hours after sport-specific training. The effect of hypochlorite on nasal epithelial cells was evaluated in vitro. RESULTS: Baseline SNOT-22 and VAS for nasal itch and impaired smell were significantly higher in swimmers compared to controls. Nasal substance P and uric acid levels were increased in elite swimmers 24-hours after swimming compared to baseline. In elite swimmers, uric acid levels 24-hours post-exercise correlated with baseline SNOT-22. As increased symptoms and inflammation were found in swimmers but not in indoor athletes, we hypothesized that hypochlorite exposure might be the underlying mechanism. In vitro, the highest dose of hypochlorite decreased nasal epithelial cell integrity and induced release of uric acid. CONCLUSION: Upper airway symptoms are frequently reported in elite swimmers. Intensive swimming resulted in a delayed increase of epithelial injury and neurogenic inflammation.

Toll-Like Receptor Agonists Modulate Wound Regeneration in Airway Epithelial Cells.

BACKGROUND: Impaired regeneration of airway epithelium may lead to persistence of inflammation and remodelling. Regeneration of injured epithelium is a complex phenomenon and the role of toll-like receptors (TLRs) in the stimulation of respiratory virus products in this process has not been established. OBJECTIVE: This study was undertaken to test the hypothesis that the wound repair process in airway epithelium is modulated by microbial products via toll-like receptors. METHODS: Injured and not-injured bronchial epithelial cells (ECs) (BEAS-2B line) were incubated with the TLR agonists poly(I:C), lipopolisacharide (LPS), allergen Der p1, and supernatants from virus-infected epithelial cells, either alone or in combination with TLR inhibitors. Regeneration and immune response in injured and not-injured cells were studied. RESULTS: Addition of either poly(I:C) or LPS to ECs induced a marked inhibition of wound repair. Supernatants from RV1b-infected cells also decreased regeneration. Preincubation of injured and not-injured ECs with TLR inhibitors decreased LPS and poly(I:C)-induced repair inhibition. TGF-ß and RANTES mRNA expression was higher in injured ECs and IFN-α, IFN-ß, IL-8, and VEGF mRNA expression was lower in damaged epithelium as compared to not-injured. Stimulation with poly(I:C) increased IFN-α and IFN-ß mRNA expression in injured cells, and LPS stimulation decreased interferons mRNA expression both in not-injured and injured ECs. CONCLUSION: Regeneration of the airway epithelium is modulated by microbial products via toll-like receptors.

[Effect of conditioned medium from mesenchymal stem cells on regeneration of endothelium at HCl-induced damage trachea in rats].

The purpose. Respiratory epithelium regeneration is studied in rats with tracheal damage induced by inhaling hydrochloric acid vapor. Method. Regeneration process after the chemical burn was activated by intratracheal administration of preparations obtained from the same-species mesenchymal stem cells (MSC). Results. Tracheal epithelium is shown to recover almost completely on day 3-7 after applying MSC compositions (MSCs). Closed structures containing ciliated cells similar to ciliated cells of the respiratory epithelium lining the trachea are formed in the submucosal epithelium during regeneration. These structures migrate towards epithelium and get incorporated into the damaged epithelium. This phenomenon is apparently indicative of the special mechanism of respiratory epithelium regeneration after HCl-induced injury. Conclusion. It is demonstrated in this study that cell-free MSCs instilled intratracheally promote the recovery of normal submucosal epithelium by either preventing or reducing necrosis and inflammation. Such topical MSCs administration significantly accelerates migration of ciliated cell towards the surface and de novo formation of the ciliary epithelium.

Inhibition of endotoxin-induced airway epithelial cell injury by a novel family of pyrrol derivates.

Inflammation and apoptosis are crucial mechanisms for the development of the acute respiratory distress syndrome (ARDS). Currently, there is no specific pharmacological therapy for ARDS. We have evaluated the ability of a new family of 1,2,3,5-tetrasubstituted pyrrol compounds for attenuating lipopolysaccharide (LPS)-induced inflammation and apoptosis in an in vitro LPS-induced airway epithelial cell injury model based on the first steps of the development of sepsis-induced ARDS. Human alveolar A549 and human bronchial BEAS-2B cells were exposed to LPS, either alone or in combination with the pyrrol derivatives. Rhein and emodin, two representative compounds with proven activity against the effects of LPS, were used as reference compounds. The pyrrol compound that was termed DTA0118 had the strongest inhibitory activity and was selected as the lead compound to further explore its properties. Exposure to LPS caused an intense inflammatory response and apoptosis in both A549 and BEAS-2B cells. DTA0118 treatment downregulated Toll-like receptor-4 expression and upregulated nuclear factor-κB inhibitor-α expression in cells exposed to LPS. These anti-inflammatory effects were accompanied by a significantly lower secretion of interleukin-6 (IL-6), IL-8, and IL-1ß. The observed antiapoptotic effect of DTA0118 was associated with the upregulation of antiapoptotic Bcl-2 and downregulation of proapoptotic Bax and active caspase-3 protein levels. Our findings demonstrate the potent anti-inflammatory and antiapoptotic properties of the pyrrol DTA0118 compound and suggest that it could be considered as a potential drug therapy for the acute phase of sepsis and septic ARDS. Further investigations are needed to examine and validate these mechanisms and effects in a clinically relevant animal model of sepsis and sepsis-induced ARDS.

Impact of Pulmonary Vein Cryoballoon Ablation on Bronchial Injury.

INTRODUCTION: There is a paucity of data on the mechanisms of cough and hemoptysis that sometimes ensue from cryoballoon ablation of pulmonary veins (Cryo-PV). This study specifically examined the impact of ultra-cold (≤-60 °C, 3 minutes), prolonged (>-55 °C, 6 minutes), and conventional (>-55 °C, 3 minutes) Cryo-PV on lung/bronchial injury. METHODS AND RESULTS: Four healthy adult swine underwent Cryo-PV. Each animal received Cryo-PV to the inferior common trunk and the right superior PV. In 2 animals, 1 PV was treated with 2 ultra-cold (Cryo-AUltra-cold ) and the other with 2 conventional (Cryo-AConventional ) cryoapplications. In the other 2 animals, 1 PV was ablated using 2 prolonged (Cryo-BProlonged ) and the other with 2 conventional (Cryo-BConventional ) applications. The nadir cryoballoon temperatures were lower in Cryo-AUltra-cold versus Cryo-AConventional (-66 ± 6 °C vs. -45 ± 5 °C; P = 0.001), but did not differ between Cryo-BProlonged and Cryo-BConventional (-46 ± 3 °C vs. -49 ± 3 °C; P = 0.123). Post-ablation bronchoscopy revealed immediate mucosal edema and erythema with/without bleeding in the adjacent bronchi in 100% of Cryo-AUltra-cold and 50% of Cryo-AConventional /Cryo-BConventional and Cryo-BProlonged . At 4 hours post-ablation, there were marked increases in bronchoalveolar macrophages (P <0.001), lymphocytes (P = 0.035) and neutrophils (P = 0.001). Furthermore, Cryo-AUltra-cold yielded the largest increase in the macrophage (P = 0.005) and neutrophil (P = 0.034) cell counts. While similar trends were seen in Cryo-BProlonged , these did not reach statistical significance. CONCLUSION: Cryo-PV can elicit acute bronchial inflammation, bleeding, and mucosal injury. While this was further augmented by ultra-cold cryoapplications, it was also evident to a lesser degree with prolonged and even conventional cryoapplications. The mechanism for this appears to be direct collateral injury.

Fibroblast growth factor 2 is required for epithelial recovery, but not for pulmonary fibrosis, in response to bleomycin.

The pathogenesis of pulmonary fibrosis involves lung epithelial injury and aberrant proliferation of fibroblasts, and results in progressive pulmonary scarring and declining lung function. In vitro, fibroblast growth factor (FGF) 2 promotes myofibroblast differentiation and proliferation in cooperation with the profibrotic growth factor, transforming growth factor-ß1, but the in vivo requirement for FGF2 in the development of pulmonary fibrosis is not known. The bleomycin model of lung injury and pulmonary fibrosis was applied to Fgf2 knockout (Fgf2(-/-)) and littermate control mice. Weight loss, mortality, pulmonary fibrosis, and histology were analyzed after a single intranasal dose of bleomycin. Inflammation was evaluated in bronchoalveolar lavage (BAL) fluid, and epithelial barrier integrity was assessed by measuring BAL protein and Evans Blue dye permeability. Fgf2 is expressed in mouse and human lung epithelial and inflammatory cells, and, in response to bleomycin, Fgf2(-/-) mice have significantly increased mortality and weight loss. Analysis of BAL fluid and histology show that pulmonary fibrosis is unaltered, but Fgf2(-/-) mice fail to efficiently resolve inflammation, have increased BAL cellularity, and, importantly, deficient recovery of epithelial integrity. Fgf2(-/-) mice similarly have deficient recovery of club cell secretory protein(+) bronchial epithelium in response to naphthalene. We conclude that FGF2 is not required for bleomycin-induced pulmonary fibrosis, but rather is essential for epithelial repair and maintaining epithelial integrity after bleomycin-induced lung injury in mice. These data identify that FGF2 acts as a protective growth factor after lung epithelial injury, and call into question the role of FGF2 as a profibrotic growth factor in vivo.

Tolerability and performance of BIP endotracheal tubes with noble metal alloy coating--a randomized clinical evaluation study.

BACKGROUND: Hospital acquired infections worsen the outcome of patients treated in intensive care units and are costly. Coatings with silver or metal alloys may reduce or alter the formation of biofilm on invasive medical devices. An endotracheal tube (ETT) is used to connect the patient to a ventilator and coated tubes have been tested in relation to bacterial colonization and respiratory infection. In the present study, we aimed to evaluate and compare a coated and uncoated ETT for patient symptoms and local tracheal tolerability during short term clinical use. Degree of bacterial colonization was also described. METHODS: A silver-palladium-gold alloy coating ('Bactiguard®'Infection Protection, BIP) has been extensively used on urinary tract catheters and lately also on central venous catheters. We performed a randomised, single-blinded, controlled, first in man, post Conformité Européenne (EC) certification and CE marking study, focused on Bactiguard® coated ETTs (BIP ETT). Thirty patients at a tertiary university hospital scheduled for upper abdominal elective surgery with an expected duration of anaesthesia of at least 3 h were randomised; BIP ETT (n = 20) or standard ETT (n = 10). The tolerability was assessed with a modified version of Quality of Life Head and Neck Module, QLQ-H&N35 and by inspection of the tracheal mucosa with a fibre-optic bronchoscope before intubation and at extubation. Adverse Events (AE) and bacterial adherence were also studied. Statistical evaluations were carried out with the Fisher's Exact Test, the Clopper-Pearson method, as well as a Proportional Odds Model. RESULTS: Differences between groups were identified in 2 of 8 patient related symptoms with regard to tolerability by QLQ-H&N35 (cough, p = 0.022 and dry mouth, p = 0.014 in the treatment group.). No mucosal damage was identified with bronchoscopy. A low level of bacterial colonization with normal flora, equal between groups, was seen after short-term of intubation (median 5 h). No serious Adverse Events related to the use of an ETT were observed. The results should be treated with caution due to statistical confounders, a small study size and large inter-individual variability in bacterial adhesion. CONCLUSIONS: The new device BIP ETT is well tolerated and has good clinical performance during short-term intubation. Studies with larger sample sizes and longer intubation periods (>24 h) in the ICU-setting are needed and can now be planned in order to identify possible differences in clinical outcomes. TRIAL REGISTRATION: Registered in ClinicalTrials.gov, REGISTRATION NUMBER: NCT01682486 , Date of Registration: August, 30, 2012.

[Patient safety and the prevention of skin and mucosal lesions associated with airway invasive devices]. / Segurança do paciente e a prevenção de lesões cutâneo-mucosas associadas aos dispositivos invasivos nas vias aéreas.

OBJECTIVE: To analyze the care implemented by the nursing team to promote the safety of adult patients and prevention of skin and mucosal lesions associated with the presence of lower airways invasive devices. METHOD: Study with qualitative and quantitative approach, descriptive and exploratory type, whose investigative scenarios were adult inpatient units of a hospital in the West Frontier of Rio Grande do Sul. The study subjects consisted of nurses, nursing technicians and nursing assistants. RESULTS: A total of 118 professionals were interviewed. We highlight the observed specific care with endotracheal tube and tracheostomy, management and assessment of the cuff and the criteria used to secretion aspiration. CONCLUSION: There is a superficial nursing work in the patient direct care and a differentiation in relation to the perception of nurse technicians, especially those working in the intensive care unit, who presented major property and view of the patient's clinical status.

Matrix metalloproteinase-7 coordinates airway epithelial injury response and differentiation of ciliated cells.

Matrix metalloproteinase-7 (MMP7) expression is quickly up-regulated after injury, and functions to regulate wound repair and various mucosal immune processes. We evaluated the global transcriptional response of airway epithelial cells from wild-type and Mmp7-null mice cultured at an air-liquid interface. The analysis of differentially expressed genes between genotypes after injury revealed an enrichment of functional categories associated with inflammation, cilia, and differentiation. Because these analyses suggested that MMP7 regulated ciliated cell formation, we evaluated the recovery of the airway epithelium in wild-type and Mmp7-null mice in vivo after naphthalene injury, which revealed augmented ciliated cell formation in the absence of MMP7. Moreover, in vitro studies evaluating cell differentiation in air-liquid interface cultures also showed faster ciliated cell production under Mmp7-null conditions compared with wild-type conditions. These studies identified a new role for MMP7 in attenuating ciliated cell differentiation during wound repair.

Adenosine A(1) and prostaglandin E receptor 3 receptors mediate global airway contraction after local epithelial injury.

Epithelial injury and airway hyperresponsiveness are prominent features of asthma. We have previously demonstrated that laser ablation of single epithelial cells immediately induces global airway constriction through Ca(2+)-dependent smooth muscle shortening. The response is mediated by soluble mediators released from wounded single epithelial cells; however, the soluble mediators and signaling mechanisms have not been identified. In this study, we investigated the nature of the epithelial-derived soluble mediators and the associated signaling pathways that lead to the L-type voltage-dependent Ca(2+) channel (VGCC)-mediated Ca(2+) influx. We found that inhibition of adenosine A1 receptors (or removal of adenosine with adenosine deaminase), cyclooxygenase (COX)-2 or prostaglandin E receptor 3 (EP3) receptors, epidermal growth factor receptor (EGFR), or platelet-derived growth factor receptor (PDGFR) all significantly blocked Ca(2+) oscillations in smooth muscle cells and airway contraction induced by local epithelial injury. Using selective agonists to activate the receptors in the presence and absence of selective receptor antagonists, we found that adenosine activated the signaling pathway A1R→EGFR/PDGFR→COX-2→EP3→VGCCs→calcium-induced calcium release, leading to intracellular Ca(2+) oscillations in airway smooth muscle cells and airway constriction.

NOTCH1 is required for regeneration of Clara cells during repair of airway injury.

The airways of the mammalian lung are lined with highly specialized epithelial cell types that are the targets of airborne toxicants and injury. Notch signaling plays an important role in the ontogeny of airway epithelial cells, but its contributions to recruitment, expansion or differentiation of resident progenitor/stem cells, and repair and re-establishment of the normal composition of airway epithelium following injury have not been addressed. In this study, the role of a specific Notch receptor, Notch1, was investigated by targeted inactivation in the embryonic lung epithelium using the epithelial-specific Gata5-Cre driver line. Notch1-deficient mice are viable without discernible defects in pulmonary epithelial cell-fate determination and differentiation. However, in an experimental model of airway injury, activity of Notch1 is found to be required for normal repair of the airway epithelium. Absence of Notch1 reduced the ability of a population of cells distinguished by expression of PGP9.5, otherwise a marker of pulmonary neuroendocrine cells, which appears to serve as a reservoir for regeneration of Clara cells. Hairy/enhancer of split-5 (Hes5) and paired-box-containing gene 6 (Pax6) were found to be downstream targets of Notch1. Both Hes5 and Pax6 expressions were significantly increased in association with Clara cell regeneration in wild-type lungs. Ablation of Notch1 reduced Hes5 and Pax6 and inhibited airway epithelial repair. Thus, although dispensable in developmental ontogeny of airway epithelial cells, normal activity of Notch1 is required for repair of the airway epithelium. The signaling pathway by which Notch1 regulates the repair process includes stimulation of Hes5 and Pax6 gene expression.

Diesel exhaust particles induce aberrant alveolar epithelial directed cell movement by disruption of polarity mechanisms.

Disruption of the respiratory epithelium contributes to the progression of a variety of respiratory diseases that are aggravated by exposure to air pollutants, specifically traffic-based pollutants such as diesel exhaust particles (DEP). Recognizing that lung repair following injury requires efficient and directed alveolar epithelial cell migration, this study's goal was to understand the mechanisms underlying alveolar epithelial cells response to DEP, particularly when exposure is accompanied with comorbid lung injury. Separate mechanistic steps of directed migration were investigated in confluent murine LA-4 cells exposed to noncytotoxic concentrations (0-100 µg/cm(2)) of either automobile-emitted diesel exhaust particles (DEP(A)) or carbon black (CB) particles. A scratch wound model ascertained how DEP(A) exposure affected directional cell migration and BCECF ratio fluorimetry-monitored intracellular pH (pHi). Cells were immunostained with giantin to assess cell polarity, and with paxillin to assess focal cell adhesions. Cells were immunoblotted for ezrin/radixin/moesin (ERM) to assess cytoskeletal anchoring. Data demonstrate herein that exposure of LA-4 cells to DEP(A) (but not CB) resulted in delayed directional cell migration, impaired de-adhesion of the trailing edge cell processes, disrupted regulation of pHi, and altered Golgi polarity of leading edge cells, along with modified focal adhesions and reduced ERM levels, indicative of decreased cytoskeletal anchoring. The ability of DEP(A) to disrupt directed cell migration at multiple levels suggests that signaling pathways such as ERM/Rho are critical for transduction of ion transport signals into cytoskeletal arrangement responses. These results provide insights into the mechanisms by which chronic exposure to traffic-based emissions may result in decrements in lung capacity.

Myd88 deficiency influences murine tracheal epithelial metaplasia and submucosal gland abundance.

Tracheal epithelial remodelling, excess mucus production, and submucosal gland hyperplasia are features of numerous lung diseases, yet their origins remain poorly understood. Previous studies have suggested that NF-κB signalling may regulate airway epithelial homeostasis. The purpose of this study was to determine whether deletion of the NF-κB signalling pathway protein myeloid differentiation factor 88 (Myd88) influenced tracheal epithelial cell phenotype. We compared wild-type and Myd88-deficient or pharmacologically inhibited adult mouse tracheas and determined that in vivo Myd88 deletion resulted in increased submucosal gland number, secretory cell metaplasia, and excess mucus cell abundance. We also found that Myd88 was required for normal resolution after acute tracheal epithelial injury. Microarray analysis revealed that uninjured Myd88-deficient tracheas contained 103 transcripts that were differentially expressed relative to wild-type and all injured whole tracheal samples. These clustered into several ontologies and networks that are known to functionally influence epithelial cell phenotype. Comparing these transcripts to those expressed in airway progenitor cells revealed only five common genes, suggesting that Myd88 influences tracheal epithelial homeostasis through an extrinsic mechanism. Overall, this study represents the first identification of Myd88 as a regulator of adult tracheal epithelial cell phenotype.

Prevention of intubation-induced mucosal damage using a tube coated with 2-methacryloyloxyethyl phosphorylcholine polymer.

BACKGROUND AND OBJECTIVE: Tracheal intubation is associated with various complications that include epithelial injury. Abrasion of the fragile tracheal epithelium can occur at the points of contact between the tube and mucosa subject to respiratory movement. In this original experiment, we examined the mucosal protective effect of coating endotracheal tubes with poly[2-methacryloyloxyethl phosphorylcholine (MPC)-co-n-butyl methacrylate] (PMB). METHODS: We prepared four types of tubes: tube A (control, no coating), tube B (two coats, 0.5% PMB), tube C (10 coats, 0.5% PMB) or tube D (one coat, 5% PMB). Twenty-nine beagle dogs were divided into four groups and orally intubated with tube A, B, C or D for 4±0.5 h. The cuffs of extubated tubes were stained with haematoxylin. Paraffin sections from tracheal walls in contact with the inflated cuff were stained with haematoxylin/eosin and periodic acid-Schiff. RESULTS: Cuffs of tubes A and B were strongly stained with haematoxylin because of attached epithelial cells. Stained areas in those of tubes C and D were significantly reduced. Histological analysis showed that a single coat of 5% PMB prevented epithelial abrasion and proliferation of goblet cells. Excess tracheal mucus was observed in the tube A group, but not in the tube D group. CONCLUSION: Tracheal epithelial damage caused by intubation was greatly reduced or eliminated by PMB coating on the surface of the tracheal tube.

Understanding cellular mechanisms underlying airway epithelial repair: selecting the most appropriate animal models.

Understanding the mechanisms underlying the process of regeneration and repair of airway epithelial structures demands close characterization of the associated cellular and molecular events. The choice of an animal model system to study these processes and the role of lung stem cells is debatable since ideally the chosen animal model should offer a valid comparison with the human lung. Species differences may include the complex three-dimensional lung structures, cellular composition of the lung airway as well as transcriptional control of the molecular events in response to airway epithelium regeneration, and repair following injury. In this paper, we discuss issues related to the study of the lung repair and regeneration including the role of putative stem cells in small- and large-animal models. At the end of this paper, the author discuss the potential for using sheep as a model which can help bridge the gap between small-animal model systems and humans.

Children will eat the strangest things: a 10-year retrospective analysis of foreign body and caustic ingestions from a single academic center.

BACKGROUND: Foreign body (FB) ingestions are common in children presenting to the emergency department. Health care providers are quickly challenged to determine which children need urgent endoscopy for diagnostic or therapeutic reasons. We performed a retrospective study to determine if esophageal injury caused by FB ingestion correlated to presenting signs or symptoms, location of impaction, duration of impaction, or denomination of coin (as this was the most commonly ingested FB). METHODS: A retrospective chart review of children between birth and 17 years of age who presented for esophagogastroduodenoscopy for removal of upper gastrointestinal FB was performed. Demographic data collected from all children included age, sex, and race. For children with FB ingestion, the type of FB, location of the FB, underlying gastrointestinal pathology, duration of impaction, and endoscopic findings were recorded. Descriptive analysis of the data was performed using means, medians, SD, and percentages; χ test was used to test the association between categorical variables. RESULTS: Over a 10-year period of review, a total of 3279 esophagogastroduodenoscopies were performed; 248 (7.8%) were done for FB removal. The mean age for children having endoscopy for FB removal was 3.9 (SD, 3.2) years (median, 3.1 years); there was a slight male predominance (male/female ratio = 1.6:1). The vast majority (81%) of retained FBs was coins. Most of the FBs were located in the upper esophagus (68%). Success rate for retrieval was greater for esophageal FBs (99%) than for more distally located FBs (70%; P < 0.001). Mucosal ulceration, seen in 59 children (30%), was related to a complaint of substernal pain but not vomiting, respiratory distress, or drooling. The finding of esophageal ulceration was not related to location of coin impaction or denomination of ingested coin but was related to duration of impaction and the unexpected finding of FB during chest radiograph. Underlying pathology was found more commonly in children with meat bolus impaction (100%) than in children with other FB ingestions (3.6%; P < 0.001). CONCLUSIONS: Ingestion of FBs by children remains a significant problem faced by emergency department personnel. In our study, a complaint of substernal chest pain in children with an esophageal FB predicted esophageal ulceration. Also, esophageal FBs unexpectedly found on chest radiograph or known to be present greater than 72 hours were more likely to have esophageal ulceration. These clinical and historic clues can help direct appropriate prompt referral for endoscopic removal.

Foxp1/2/4-NuRD interactions regulate gene expression and epithelial injury response in the lung via regulation of interleukin-6.

To determine the underlying mechanism of Foxp1/2/4-mediated transcriptional repression, a yeast two-hybrid screen was performed that identified p66beta, a transcriptional repressor and component of the NuRD chromatin-remodeling complex. We show that direct interactions between Foxp1/4 and p66beta are mediated by the CR2 domain within p66beta and the zinc finger/leucine zipper repression domain found in Foxp1/2/4. These direct interactions are functionally relevant as overexpression of p66beta in combination with Foxp factors cooperatively represses Foxp target gene expression, whereas loss of p66 and Foxp factors results in de-repression of endogenous Foxp target genes in lung epithelial cells. Moreover, the NuRD components HDAC1/2 associate in a macromolecular complex with Foxp proteins, and loss of expression or inhibition of HDAC1/2 activity leads to de-repression of Foxp target gene expression. Importantly, we show in vivo that Foxp1 and HDAC2 act cooperatively to regulate expression of the cytoprotective cytokine interleukin-6, which results in increased resistance to hyperoxic lung injury in Foxp1/HDAC2 compound mutant animals. These data reveal an important interaction between the Foxp transcription factors and the NuRD chromatin-remodeling complex that modulates transcriptional repression critical for the lung epithelial injury response.

Wound-induced TGF-ß1 and TGF-ß2 enhance airway epithelial repair via HB-EGF and TGF-α.

The abundance of transforming growth factor-beta (TGF-ß) in normal airway epithelium suggests its participation in physiological processes to maintain airway homeostasis. The current study was designed to address the hypothesis that TGF-ß1 and TGF-ß2 might contribute to normal reparative response of airway epithelial cells (AECs). Treatments with exogenous TGF-ß1 or TGF-ß2 significantly enhanced wound repair of confluent AEC monolayers. Mechanical injury of AEC monolayers induced production of both TGF-ß1 and TGF-ß2. Wound repair of AECs was significantly reduced by a specific inhibitor of TGF-ß type I receptor kinase activity. We investigated whether the TGF-ß-enhanced repair required epidermal growth factor receptor (EGFR) transactivation and secretion of EGFR ligands. Both TGF-ß1 and TGF-ß2 enhanced EGFR phosphorylation and induced production of heparin-binding EGF-like growth factor (HB-EGF) and transforming growth factor-alpha (TGF-α) in AECs. Moreover, treatment with a broad-spectrum metalloproteinase inhibitor or anti-HB-EGF and anti-TGF-α antibodies inhibited the wound repair and the EGFR phosphorylation by TGF-ß1 and TGF-ß2, indicating that the TGF-ß1 and TGF-ß2 effects on wound repair required the release of HB-EGF and TGF-α. Our data, for the first time, have shown that both TGF-ß1 and TGF-ß2 play a stimulatory role in airway epithelial repair through EGFR phosphorylation following autocrine production of HB-EGF and TGF-α. These findings highlight an important collaborative mechanism between TGF-ß and EGFR in maintaining airway epithelial homeostasis.

Analysis of airway epithelial regeneration and repair following endobronchial brush biopsy in sheep.

Understanding the fundamental processes involved in repairing the airway wall following injury is fundamental to understanding the way in which these processes are perturbed during disease pathology. Indeed complex diseases such as asthma and chronic obstructive pulmonary disease (COPD) have at their core evidence of airway wall remodeling processes that play a crucial functional role in these diseases. The authors sought to understand the dynamic cellular events that occur during bronchial airway epithelial repair in sheep. The injury was induced by endobronchial brush biopsy (BBr), a process that causes epithelial débridement and induces a consequential repair process. In addition, the current experimental protocol allowed for the time-dependent changes in airway wall morphology to be studied both within and between animals. The initial débridement was followed by evidence of dedifferentiation in the intact epithelium at the wound margins, followed by proliferation of cells both within the epithelium and in the deeper wall structures, notably in association with the submucosal glands and smooth muscle bundles. Seven days after injury, although the airway wall was thickened at the site of damage, the epithelial layer was intact, with evidence of redifferentiation. These studies, in demonstrating broad agreement with previous studies in small animals, indicate the wider relevance of this system as a comparative model and should provide a solid basis upon which to further characterize the critical cellular and molecular interactions that underlie both effective restitution and pathological repair.