Normal murine respiratory tract has its mucus concentrated in clouds based on the Muc5b mucin.

The organization of the normal airway mucus system differs in small experimental animals from that in humans and large mammals. To address normal murine airway mucociliary clearance, Alcian blue-stained mucus transport was measured ex vivo on tracheal tissues of naïve C57BL/6, Muc5b-/-, Muc5ac-/-, and EGFP-tagged Muc5b reporter mice. Close to the larynx with a few submucosal glands, the mucus appeared as thick bundles. More distally in the trachea and in large bronchi, Alcian blue-stained mucus was organized in cloud-like formations based on the Muc5b mucin. On tilted tissue, the mucus clouds moved upward toward the larynx with an average velocity of 12 µm/s compared with 20 µm/s for beads not associated with clouds. In Muc5ac-/- mice, Muc5b formed mucus strands attached to the tissue surface, while in Muc5b-/- mice, Muc5ac had a more variable appearance. The normal mouse lung mucus thus appears as discontinuous clouds, clearly different from the stagnant mucus layer in diseased lungs.

Submucosal gland neoplasms of the esophagus: an update and review.

Submucosal glands (SMGs) present throughout human esophagus with clusters at either the upper third or lower third of the organ. SMGs tend to atrophy with age, and neoplasms arising in these glands are rare. In order to bring convenience to diagnosis, we summarize the histopathologic characteristics of all esophageal submucosal gland tumors (SGTs). Due to the morphological similarity, the nomenclature of salivary tumors is adopted for SGTs. However, there is great confusion about the definition and histogenesis of these tumors, especially the malignant subtypes. In the literature, esophageal mucoepidermoid carcinoma and adenoid cystic carcinoma usually adjoin the surface squamous epithelium and coexist with intraepithelial neoplasia or invasive squamous cell carcinoma (SCC). In addition, the typical gene alterations of salivary tumors have not been reported in these SGTs. Therefore, we propose to apply stringent diagnostic criteria to esophageal SGTs so as to exclude mimickers that are SCCs with various degree of SMG differentiation.

Mutation W222L at the Receptor Binding Site of Hemagglutinin Could Facilitate Viral Adaption from Equine Influenza A(H3N8) Virus to Dogs.

An outbreak of respiratory disease caused by the equine-origin influenza A(H3N8) virus was first detected in dogs in 2004 and since then has been enzootic among dogs. Currently, the molecular mechanisms underlying host adaption of this virus from horses to dogs is unknown. Here, we have applied quantitative binding, growth kinetics, and immunofluorescence analyses to elucidate these mechanisms. Our findings suggest that a substitution of W222L in the hemagglutinin of the equine-origin A(H3N8) virus facilitated its host adaption to dogs. This mutation increased binding avidity of the virus specifically to receptor glycans with N-glycolylneuraminic acid (Neu5Gc) and sialyl Lewis X (SLeX) motifs. We have demonstrated these motifs are abundantly located in the submucosal glands of dog trachea. Our findings also suggest that in addition to the type of glycosidic linkage (e.g., α2,3-linkage or α2,6-linkage), the type of sialic acid (Neu5Gc or 5-N-acetyl neuraminic acid) and the glycan substructure (e.g., SLeX) also play an important role in host tropism of influenza A viruses.IMPORTANCE Influenza A viruses (IAVs) cause a significant burden on human and animal health, and mechanisms for interspecies transmission of IAVs are far from being understood. Findings from this study suggest that an equine-origin A(H3N8) IAV with mutation W222L at its hemagglutinin increased binding to canine-specific receptors with sialyl Lewis X and Neu5Gc motifs and, thereby, may have facilitated viral adaption from horses to dogs. These findings suggest that in addition to the glycosidic linkage (e.g., α2,3-linked and α2,6-linked), the substructure in the receptor saccharides (e.g., sialyl Lewis X and Neu5Gc) could present an interspecies transmission barrier for IAVs and drive viral mutations to overcome such barriers.

Comparison of esophageal submucosal glands in experimental models for esophagus tissue engineering applications.

OBJECTIVE: Esophagus tissue engineering holds promises to overcome the limitations of the presently employed esophageal replacement procedures. This study investigated 5 animal models for esophageal submucosal glands (ESMG) to identify models appropriate for regenerative medicine applications. Furthermore, this study aimed to measure geometric parameters of ESMG that could be utilized for fabrication of ESMG-specific scaffolds for esophagus tissue engineering applications. METHODS: Ovine, avian, bovine, murine, and porcine esophagus were investigated using Hematoxylin-Eosin (HE), Periodic Acid Schiff (PAS), and Alcian Blue (AB), with AB applied in 3 pH levels (0.2, 1.0, and 2.5) to detect sulphated mucous. Celleye® (version F) was employed to gain parametric data on ESMGs (size, perimeter, distance to lumen, and acini concentration) necessary for scaffold fabrication. RESULTS: Murine, bovine, and ovine esophagus were devoid of ESMG. Avian esophagus demonstrated sulphated acid mucous producing ESMGs with a holocrine secretion pattern, whereas sulphated acid and neutral mucous producing ESMGs with a merocrine secretion pattern were observed in porcine esophagus. Distance of ESMGs to lumen ranged from 127-340 µm (avian) to 916-983 µm (porcine). ESMGs comprised 35% (avian) to 45% (porcine) area of the submucosa. ESMG had an area of 125000 µm2 (avian) to 580000 µm2 (porcine). CONCLUSION: Avian and porcine esophagus possesses ESMGs. However, porcine esophagus correlates with data available on human ESMGs. Geometric and parametric data obtained from ESMG are valuable for the fabrication of ESMG-specific scaffolds for esophagus tissue engineering using the hybrid construct approach.

TLR7 agonist attenuates acetylcholine-induced, Ca2+ -dependent ionic currents in swine tracheal submucosal gland cells.

NEW FINDINGS: What is the central question of this study? Does Toll-like receptor 7 (TLR7) have any direct effects on Ca2+ -dependent physiological function of tracheal submucosal gland cells? What is the main finding and its importance? TLR7 is co-localized with SERCA2 in tracheal submucosal gland cells and causes a rapid attenuation of acetylcholine (ACh)-induced, Ca2+ -dependent ionic currents through the activation of SERCA2-dependent Ca2+ clearance. TLR7 is abundantly expressed in the airways of both swine and healthy human subjects, but is significantly downregulated in chronic obstructive pulmonary disease (COPD) airways. These findings suggest that a dysfunction of TLR7 in COPD removes the brake on ACh-induced serous secretion during viral infections, resulting in prolonged airway hypersecretion, and that it is one of the triggers of COPD exacerbations. ABSTRACT: Airway surface fluids are mainly secreted from submucosal glands (SMGs) and play important roles in the defence of airways via the activation of mucociliary transport. Toll-like receptor 7 (TLR7) recognizes and eliminates single stranded RNA (ssRNA) viruses through the induction of innate immunity. However, there is no obvious connection between TLR7 and mucus secretion, aside from TLR7 recognizing ssRNA viruses, which are often associated with airway hypersecretion in chronic obstructive pulmonary disease (COPD). Here, we investigated whether TLR7 has any direct effects on the Ca2+ -dependent physiological function of tracheal SMG cells. Patch-clamp analyses revealed that TLR7 ligand inhibited the acetylcholine (ACh)-induced ionic currents in isolated tracheal SMG cells. Intracellular calcium assays and pharmacological analyses revealed that TLR7 attenuated the transient rises in the intracellular calcium concentration evoked by ACh by activating sarco/endoplasmic reticulum Ca2+ -ATPase 2 (SERCA2). Immunofluorescence staining and immunohistochemical staining revealed that TLR7 was co-localized with SERCA2. These findings suggest that the activation of TLR7 during viral infections contributes to the rapid attenuation of ACh-induced ionic currents through an increase in SERCA2-dependent Ca2+ clearance in healthy airway SMG cells. Our study also revealed that TLR7 expression was significantly downregulated in COPD airways. Based on these findings, we speculate that a dysfunction of TLR7 may not only have an adverse effect on the elimination of these viruses but also remove the brake on ACh-induced serous secretion, resulting in prolonged hypersecretion and acting as one of the triggers of COPD exacerbations.

Multipotent Myoepithelial Progenitor Cells Are Born Early during Airway Submucosal Gland Development.

Airway submucosal glands (SMGs) are facultative stem cell niches for the surface epithelium, but the phenotype of the SMG-derived progenitor cells remains unclear. In other organs, glandular myoepithelial cells (MECs) have been proposed to be multipotent progenitors for luminal cells. We sought to determine the developmental phase during which mouse tracheal glandular MECs are born and whether these MECs are progenitors for other cell phenotypes during SMG morphogenesis. To approach this question, we localized two MEC protein markers (α-smooth muscle actin [αSMA/ACTA2] and smooth muscle myosin heavy chain 11 [SMMHC/MYH11]) during various stages of SMG development (placode, elongation, branching, and differentiation) and used ACTA2-CreERT2 and MYH11-CreERT2 transgenic mice to fate map MEC-derived lineages during SMG morphogenesis. Both αSMA- and SMMHC-expressing cells emerged early after placode formation and during the elongation phase of SMG development. Lineage tracing in newborn mice demonstrated that lineage-positive MECs are born at the tips of invading tubules during the elongation phase of gland development. Lineage-positive MECs born within the first 7 days after birth gave rise to the largest percentage of multipotent progenitors capable of contributing to myoepithelial, serous, mucous, and ductal cell lineages. Serial tamoxifen-induction of both Cre-driver lines demonstrated that lineage-positive multipotent MECs contribute to ∼ 60% of glandular cells by 21 days after birth. In contrast, lineage-traced MECs did not contribute to cell types in the surface airway epithelium. These findings demonstrate that MECs born early during SMG morphogenesis are multipotent progenitors with the capacity to differentiate into other glandular cell types.

Siglec-8 and Siglec-9 binding specificities and endogenous airway ligand distributions and properties.

Siglecs are transmembrane sialoglycan binding proteins, most of which are expressed on leukocyte subsets and have inhibitory motifs that translate cell surface ligation into immune suppression. In humans, Siglec-8 on eosinophils, mast cells and basophils and Siglec-9 on neutrophils, monocytes and some T-cells, mediate immune cell death, inhibition of immune mediator release and/or enhancement of anti-inflammatory mediator release. Endogenous sialoglycan ligands in tissues, mostly uncharacterized, engage siglecs on leukocytes to inhibit inflammation. Glycan array analyses demonstrated that Siglec-8, Siglec-9 and their mouse counterparts Siglec-F and Siglec-E (respectively) have distinct glycan binding specificities, with Siglec-8 more structurally restricted. Since siglecs are involved in lung inflammation, we studied Siglec-8 and Siglec-9 ligands in human lungs and airways. Siglec-8 ligands are in tracheal submucosal glands and cartilage but not airway epithelium or connective tissues, whereas Siglec-9 ligands are broadly distributed. Mouse airways do not have Siglec-8 ligands, whereas Siglec-9 ligands are on airways of both species. Extraction of human airways and lung followed by electrophoretic resolution and siglec blotting revealed Siglec-8 ligands in extracts of human trachea and cultured tracheal gland cells, but not parenchyma or cultured airway epithelial cells whereas Siglec-9 ligands were extracted from all airway and lung tissues and cells tested. Siglec-8 and Siglec-9 ligands in airways appear to be high molecular weight O-linked sialoglycoproteins. These data reveal differential glycan specificities of Siglec-8, Siglec-9 and their mouse counterparts Siglec-F and Siglec-E, and the tissue distributions and molecular characteristics of Siglec-8 and Siglec-9 sialoglycan ligands on human airways and lungs.

Glandular Proteome Identifies Antiprotease Cystatin C as a Critical Modulator of Airway Hydration and Clearance.

Defects in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel lead to viscous secretions from submucosal glands that cannot be properly hydrated and cleared by beating cilia in cystic fibrosis (CF) airways. The mechanisms by which CFTR, and the predominant epithelial sodium channel (ENaC), control the hydration and clearance of glandular secretions remain unclear. We used a proteomics approach to characterize the proteins contained in CF and non-CF submucosal gland fluid droplets and found that differentially regulated proteases (cathepsin S and H) and their antiprotease (cystatin C) influenced the equilibration of fluid on the airway surface and tracheal mucociliary clearance (MCC). Contrary to prevailing models of airway hydration and clearance, cystatin C, or raising the airway surface liquid (ASL) pH, inhibited cathepsin-dependent ENaC-mediated fluid absorption and raised the height of ASL, and yet decreased MCC velocity. Importantly, coupling of both CFTR and ENaC activities were required for effective MCC and for effective ASL height equilibration after volume challenge. Cystatin C-inhibitable cathepsins controlled initial phases of ENaC-mediated fluid absorption, whereas CFTR activity was required to prevent ASL dehydration. Interestingly, CF airway epithelia absorbed fluid more slowly owing to reduced cysteine protease activity in the ASL but became abnormally dehydrated with time. Our findings demonstrate that, after volume challenge, pH-dependent protease-mediated coupling of CFTR and ENaC activities are required for rapid fluid equilibration at the airway surface and for effective MCC. These findings provide new insights into how glandular fluid secretions may be equilibrated at the airway surface and how this process may be impaired in CF.

Understanding the development of the respiratory glands.

BACKGROUND: The submucosal glands (SMGs) of the respiratory system are specialized structures essential for maintaining airway homeostasis. The significance of SMGs is highlighted by their involvement in respiratory diseases such as cystic fibrosis, asthma and chronic bronchitis, where their phenotype and function are severely altered. Uncovering the normal development of the airway SMGs is essential to elucidate their role in these disorders, however, very little is known about the cellular mechanisms and intracellular signals involved in their morphogenesis. RESULTS: This review describes in detail the embryonic developmental journey of the nasal SMGs and the postnatal development of the tracheal SMGs in the mouse. Current knowledge of the genes and signalling molecules involved in SMG organogenesis is also explored. CONCLUSION: Here we review the temporal localisation and development of the murine respiratory glands in the hope of stimulating further research into the mechanisms required for successful SMG patterning and function.

A spatial model of fluid recycling in the airways of the lung.

The genetic disease cystic fibrosis (CF) is a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, and results in viscous mucus and impaired mucociliary clearance leading to chronic recurring pulmonary infections. Although extensive experimental research has been conducted over the last few decades, CF lung pathophysiology remains controversial. There are two competing explanations for the observed depletion of periciliary liquid (PCL) in CF lungs. The low volume hypothesis assumes fluid hyperabsorption through surface epithelia due to an over-active epithelial Na(+) channel (ENaC), and the low secretion hypothesis assumes inspissated mucins secreted from glands due to lack of serous fluid secreted from gland acini. We present a spatial mathematical model that reflects in vivo fluid recycling via submucosal gland (SMG) secretion, and absorption through surface epithelia. We then test the model in CF conditions by increasing ENaC open probability and decreasing SMG flux while simultaneously reducing CFTR open probability. Increasing ENaC activity only results in increased fluid absorption across surface epithelia, as seen in in vitro experiments. However, combining potential CF mechanisms results in markedly less fluid absorbed while providing the largest reduction in PCL volume, suggesting that a compromise in gland fluid secretion dominates over increased ENaC activity to decrease the amount of fluid transported transcellularly in CF lungs in vivo. Model results also indicate that a spatial model is necessary for an accurate calculation of total fluid transport, as the effects of spatial gradients can be severe, particularly in close proximity to the SMGs.

Progenitor cells in proximal airway epithelial development and regeneration.

Multiple distinct epithelial domains are found throughout the airway that are distinguishable by location, structure, function, and cell-type composition. Several progenitor cell populations in the proximal airway have been identified to reside in confined microenvironmental niches including the submucosal glands (SMGs), which are embedded in the tracheal connective tissue between the surface epithelium and cartilage, and basal cells that reside within the surface airway epithelium (SAE). Current research suggests that regulatory pathways that coordinate development of the proximal airway and establishment of progenitor cell niches may overlap with pathways that control progenitor cell responses during airway regeneration following injury. SMGs have been shown to harbor epithelial progenitor cells, and this niche is dysregulated in diseases such as cystic fibrosis. However, mechanisms that regulate progenitor cell proliferation and maintenance within this glandular niche are not completely understood. Here we discuss glandular progenitor cells during development and regeneration of the proximal airway and compare properties of glandular progenitors to those of basal cell progenitors in the SAE. Further investigation into glandular progenitor cell control will provide a direction for interrogating therapeutic interventions to correct aberrant conditions affecting the SMGs in diseases such as cystic fibrosis, chronic bronchitis, and asthma.

Sox2 modulates Lef-1 expression during airway submucosal gland development.

Tracheobronchial submucosal glands (SMGs) are derived from one or more multipotent glandular stem cells that coalesce to form a placode in surface airway epithelium (SAE). Wnt/ß-catenin-dependent induction of lymphoid enhancer factor (Lef-1) gene expression during placode formation is an early event required for SMG morphogenesis. We discovered that Sox2 expression is repressed as Lef-1 is induced within airway SMG placodes. Deletion of Lef-1 did not activate Sox2 expression in SMG placodes, demonstrating that Lef-1 activation does not directly inhibit Sox2 expression. Repression of Sox2 protein in SMG placodes occurred posttranscriptionally, since the activity of its endogenous promoter remained unchanged in SMG placodes. Thus we hypothesized that Sox2 transcriptionally represses Lef-1 expression in the SAE and that suppression of Sox2 in SMG placodes activates Wnt/ß-catenin-dependent induction of Lef-1 during SMG morphogenesis. Consistent with this hypothesis, transcriptional reporter assays, ChIP analyses, and DNA-protein binding studies revealed a functional Sox2 DNA binding site in the Lef-1 promoter that is required for suppressing ß-catenin-dependent transcription. In polarized primary airway epithelium, Wnt induction enhanced Lef-1 expression while also inhibiting Sox2 expression. Conditional deletion of Sox2 also enhanced Lef-1 expression in polarized primary airway epithelium, but this induction was significantly augmented by Wnt stimulation. Our findings provide the first evidence that Sox2 acts as a repressor to directly modulate Wnt-responsive transcription of the Lef-1 gene promoter. These studies support a model whereby Wnt signals and Sox2 dynamically regulate the expression of Lef-1 in airway epithelia and potentially also during SMG development.

18F-DCFPyL PSMA PET/CT Tracheobronchial Uptake in Patients with Prostate Cancer: Incidence and Etiology.

We evaluated the incidence and potential etiology of tracheobronchial uptake in patients being evaluated by 18F-DCFPyL PET/CT for prostate cancer (PCa). Methods: The study included a consecutive 100 PCa patients referred for 18F-DCFPyL PET/CT. The PET/CT scans were retrospectively reviewed. The presence or absence of physiologic tracheobronchial uptake on PET/CT was recorded. To further evaluate tracheal prostate-specific membrane antigen (PSMA) expression, immunohistochemistry was performed on tracheal samples taken from 2 men who had surgical resection of lung cancer. Results: Tracheal uptake was present in 31 of 100 patients (31%). When tracheal uptake was present, the SUVmax was significantly higher in the left main bronchus (mean, 2.7) than in the right (mean, 2.3) (P < 0.001). Histopathologic testing of tracheobronchial samples showed PSMA expression in bronchial submucosal glands. Conclusion: In PCa patients undergoing 18F-DCFPyL PET/CT, tracheobronchial uptake occurred in 31% of patients. This is attributed to normal physiologic PSMA expression in bronchial submucosal glands.

Airway Serous Cells: A Comparative Study of Spatial Distribution and Abundance among Species.

The conducting airways of the respiratory system play a crucial role in filtering, humidifying, and directing air into the lungs. Among the specialized cell types within these airways, airway serous cells are notable for their secretion of watery, protein-rich fluids and enzymes, which contribute to maintaining airway surface liquid homeostasis and defending against pathogens. However, the distribution and abundance of serous cells across different species in the conducting airways remain poorly understood. In this study, we addressed this gap by investigating the spatial distribution of the airway serous cell-specific marker BPI fold containing family A member 1 (BPIFA1) in humans, pigs, and mice. Our findings demonstrate significant variations in the distribution and abundance of serous cells among these species, potentially reflecting their different respiratory anatomy and evolutionary adaptations to diverse environmental challenges and respiratory demands. In humans and pigs, airway serous cells are predominantly found in the submucosal glands of the trachea and segmental bronchi, frequently overlapping with lysozyme-positive secretory cells. In contrast, rodents like mice exhibit a distinct pattern where serous cells are scarce in submucosal glands. Instead, rodent serous cells are primarily located at the epithelial surface from the trachea to the main bronchi, where many co-express the Club cell-specific protein SCGB1A1. The abundance of serous cells diminishes progressively in the intrapulmonary airways. Given that rodent models are widely utilized in respiratory research, understanding anatomical and cellular differences in airway serous cells is critical for interpreting experimental outcomes and translating findings to human respiratory diseases and therapeutic strategies. This comparative analysis enhances our understanding of airway biology across species and informs the selection and interpretation of animal models in respiratory studies.

[Morphology of the esophagus of ferrets and expression profile of molecular markers].

OBJECTIVE: To examine the morphological characteristics and the expression profile of molecular markers of ferret esophagus and assess the feasibility of using ferrets as animal models for studying human esophageal diseases. METHODS: Frozen sections and paraffin- embedded specimens of the esophageal tissues were obtained from adult ferrets (aged 6 to 8 months) and ferrets aged 1 day, 3 days, 5 days, 1 week and 2 weeks. HE staining and periodic acid-Schiff (PAS) staining were used for morphological analysis of the esophageal submucosal glands (SMGs) of adult ferrets, and the expressions of MUC5B and MUC5AC were tested using Mucin staining; The expressions of cytokeratins (CK4, CK5, CK7, CK8, CK14, CK17, CK18, CK19, and CK20) in adult ferret esophagus were examined using HE staining and immunofluorescence assay. The expressions of LEF1 in the esophageal epithelium and SMGs were detected with immunofluorescence assay. RESULTS: In adult ferrets, the esophageal SMGs were connective tissues below the muscularis mucosa of the esophagus with secretory functions. Cytokeratins were expressed differentially in different esophageal cells: CK4, CK8 and CK20 were expressed mainly in the mucous cells, ductal cells and epithelial cells, respectively, while the mucous cells expressed the largest variety of cytokeratins. Mucin staining showed positive MUC5B and MUC5AC expression in the cytoplasm and lumen of adult ferret esophageal glands. Lectin from DBA, ECL, GSLI, GSL Ⅱ, SBA, Tacalin bioylated, ULEX, WGA, GSL Ⅰ and GSL Ⅱ were expressed on ductal cell membrane, and ECL, PNA and WGA were detected on epithelial cell membrane. Lectin with ConA, PHA-E and PHA-L were expressed on serous cell membrane. Immunofluorescence assay showed that LEF1 in the developing glands were visible from 3 days to 1 week of age and then disappeared as the glands matured. The intensity of LEF1 expression in the esophageal glands differed significantly between ferrets aged 1 to 7 days and those aged two weeks. CONCLUSION: Ferrets and human share similar esophageal tissue structures and some common molecular markers, suggesting the possibility of using ferrets as animal models of human esophageal diseases.

Age-Related Increase of Collagen/Fibrin Deposition and High PAI-1 Production in Human Nasal Polyps.

Objective: Our previous studies showed an age-related increased prevalence of nasal polyps (NP) and reduced production of S100A8/9 in elderly patients with chronic rhinosinusitis with NP (CRSwNP). In this study, we investigated an unbiased age-related gene expression profile in CRSwNP subjects and healthy controls, and further identified the differences in their tissue remodeling. Methods: Microarrays using NP and uncinate tissues from health controls (elderly, age ≥65 vs. non-elderly, age 18-49) were performed, and differentially regulated genes were analyzed. Quantitative real-time PCR (qPCR), Immunostaining, Periodic acid-Schiff (PAS), trichrome staining, Western blot, and ELISA were performed for further investigation. Results: Microarrays identified differentially expressed genes according to disease and age; 278 in NP vs. controls, 75 in non-elderly NP vs. non-elderly controls, and 32 in elderly NP vs. elderly controls. qPCR confirmed that the PLAT gene was downregulated and the SERPINB2 gene upregulated in NP vs. controls. The serous glandular cell-derived antimicrobial protein/peptide-related genes such as BPIFB3, BPIFB2, LPO, and MUC7 were remarkably reduced in NP, regardless of age. SERPINE1 gene (plasminogen activator inhibitor-1, PAI-1) expression was significantly increased in elderly NP versus elderly controls. IHC and western blot confirmed significantly decreased production of MUC7 and LPO in NP versus controls. There was a trend of age-related reduction of submucosal gland cells in normal controls. Trichrome and immunofluorescence staining demonstrated an age-related increase of collagen and fibrin deposition in NP, consistent with increased PAI-1 production. Conclusion: This study demonstrated age-related differential glandular remodeling patterns and fibrosis in NP and normal controls. PAI-1 expression was significantly increased in elderly NP versus elderly controls, suggesting PAI-1 as a potential treatment target in elderly NP.

Role of submucosal glands in the development and progression of carcinoma in Barrett's oesophagus.

Oesophageal submucosal glands secrete mucins and other chemicals that are believed to serve as protectants of the mucosal surface from luminal noxious agents, either ingested or refluxed. Changes in the type, distribution or number of submucosal glands may contribute to, or be associated with, the development of Barrett's oesophagus and progression to cancer. The aim of this study was to investigate the anatomical, morphological and immunohistochemical characteristics of submucosal glands in Barrett's oesophagus-associated neoplasia in 64 oesophageal resections for Barrett's oesophagus-associated adenocarcinoma and 32 squamous cell carcinomas (as a control group). Gland density was not significantly different between the oesophageal adenocarcinoma (0.91/cm) and squamous cell carcinoma (0.81/cm) groups (p=0.7). In the oesophageal adenocarcinoma group, glands underlying Barrett's oesophagus-associated neoplastic epithelium showed a significant decrease in the percentage of mucinous acini and a significant increase in the percentage of atrophic acini compared to glands underlying epithelium without dysplasia or carcinoma (74% vs 83%, p=0.03; and 24% vs 14%, p=0.01). There was also an increase in the percentage of glands with moderate to severe inflammation underlying neoplastic epithelium compared to glands underlying epithelium without dysplasia or carcinoma (53% vs 33%, p=0.001). None of these differences was seen in the squamous cell carcinoma group. The immunohistochemical characteristics of the different histological subtypes were also distinct. Atrophic and oncocytic acini were diffusely and strongly positive for CK7, SOX2, SOX9 and CK5/6 (a progenitor cell phenotype) while mucinous acini showed weak or moderate staining for those markers. Our results suggest that submucosal glands play a role in the progression of neoplasia, possibly by offering less protection to the mucosal surface of the oesophageal epithelium from chemical injury.

A Brief History of Bronchitis in England and Wales.

Chronic bronchitis is associated with hypertrophy of airway submucosal glands and with mucus and squamous metaplasia of the surface epithelium. A historical review of research on these and other pathological changes is provided. Next, from annual reports of the Registrar-General's Office (and later the Office of National Statistics), death rates per unit population from acute and chronic bronchitis (a term that here includes chronic obstructive pulmonary disease [COPD]) are calculated for England and Wales from 1838 to the present. It is argued that a large increase in the death rate between 1838 and 1879, from all forms of bronchitis combined, was due primarily to increased levels of atmospheric coal smoke, whereas a decrease from 1879 to 1935 was due to progressively cleaner air. Between 1935 and the mid-1960s, mortality from chronic bronchitis among men increased dramatically, after which it has fallen, a pattern that parallels changes in cigarette smoking. Finally, a brief historical review of the treatments for chronic bronchitis is presented.

Progress in understanding mucus abnormalities in cystic fibrosis airways.

Normal airways below the carina maintain an essentially sterile environment via a multi-pronged innate defence system that includes mucus clearance via mucociliary clearance and cough, multiple antimicrobials and cellular components including macrophages and neutrophils. In cystic fibrosis (CF), loss of CFTR function compromises these defences, and with present standard of care virtually all people with CF eventually develop mucus accumulation, plugging and chronic infections. This review focuses on how mucus is affected by CFTR loss.

Secretory IgA from submucosal glands does not compensate for its airway surface deficiency in chronic obstructive pulmonary disease.

Secretory immunoglobulin A (SIgA) reaches the airway lumen by local transcytosis across airway epithelial cells or with tracheobronchial submucosal gland secretions. In chronic obstructive pulmonary disease (COPD), deficiency of SIgA on the airway surface has been reported. However, reduction of SIgA levels in sputum and bronchoalveolar lavage (BAL) fluid has not been consistently observed. To explain this discrepancy, we analyzed BAL fluid and lung tissue from patients with COPD and control subjects. Immunohistochemical analysis of large and small airways of COPD patients showed that MUC5AC is the predominant mucin expressed by airway epithelial cells, whereas MUC5B is expressed in submucosal glands of large airways. Dual immunostaining with anti-IgA and anti-MUC5B antibodies showed reduction of IgA on the airway surface as well as accumulation of IgA within MUC5B-positive luminal mucus plugs, suggesting that luminal SIgA originates from submucosal glands in COPD patients. We found that the concentration of SIgA in BAL is inversely correlated with forced expiratory volume in 1 s (FEV1) in COPD, but that the ratio of SIgA/MUC5B is a better predictor of FEV1, particularly in patients with moderate COPD. Together, these findings suggest that SIgA production by submucosal glands, which are expanded in COPD, is insufficient to compensate for reduced SIgA transcytosis by airway epithelial cells. Localized SIgA deficiency on the surface of small airways is associated with COPD progression and represents a potential new therapeutic target in COPD.