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Larval urodeles are provided with external gills involved, along with the skin, in gas exchange and osmoregulation. Gills and skin epithelia are different, each showing a peculiar set of specialized cells but both provided with Leydig cells (LCs). Information on LCs in the gills is lacking as the literature has focused primarily on the epidermis. Contradictory and fragmentary results highlight that LCs origin, fate, and functions remain not fully understood. Here, we investigated the morpho‐functional differences of LCs in the skin and gills of Lissotriton italicus larvae for the first time. LCs showed the same morphological and ultrastructural features in both tissues, even if LCs were significantly larger in the epidermis. Despite the uniform morphology within the LCs population, the proliferative ability was different. The putative diversity in the mucus composition was evaluated using a panel of 4 lectins as markers of specific carbohydrate moieties, revealing that sites of specific glycoconjugates were comparable in two tissues. To disclose the involvement of LCs in water storage and transport, immunofluorescence assay for aquaporin‐3 has also been performed, demonstrating the expression of this protein only in gills epithelium. By demonstrating that LCs can multiply by cell division in gills, our results will also contribute to the discussion about their proliferative ability. Finally, we found that the LCs cytoplasm is rich in glycoconjugates, which are involved in many diverse and essential functions in vertebrates. Research Highlights: In gills LCs can multiply by cell division and express aquaporin‐3 demonstrating a tissue‐specific role of LCs.LCs cytoplasm is rich in glycoconjugates.LCs population show a uniform morphology in both gills and skin. [ABSTRACT FROM AUTHOR]

Introduction: Although communal smoking of hookah by means of water pipes is perceived to be a safe alternative to cigarette smoking, the effects of hookah smoke in respiratory epithelia have not been well characterized. This study evaluated epigenomic and transcriptomic effects of hookah smoke relative to cigarette smoke in human respiratory epithelial cells. Methods: Primary normal human small airway epithelial cells from three donors and cdk4 and hTERT-immortalized small airway epithelial cells and human bronchial epithelial cells were cultured for 5 days in normal media with or without cigarette smoke condensates (CSCs) or water pipe condensates (WPCs). Cell count, immunoblot, RNA sequencing, quantitative real-time reverse-transcriptase polymerase chain reaction, methylation-specific polymerase chain reaction, and quantitative chromatin immunoprecipitation techniques were used to compare effects of hookah and cigarette smoke on cell proliferation, global histone marks, gene expression, and promoter-related chromatin structure. Results: CSC and WPC decreased global H4K16ac and H4K20me3 histone marks and mediated distinct and overlapping cancer-associated transcriptome signatures and pathway modulations that were cell line dependent and stratified across lung cancer cells in a histology-specific manner. Epiregulin encoding a master regulator of EGFR signaling that is overexpressed in lung cancers was up-regulated, whereas FILIP1L and ABI3BP encoding mediators of senescence that are repressed in lung cancers were down-regulated by CSC and WPC. Induction of epiregulin and repression of FILIP1L and ABI3BP by these condensates coincided with unique epigenetic alterations within the respective promoters. Conclusions: These findings support translational studies to ascertain if hookah-mediated epigenomic and transcriptomic alterations in cultured respiratory epithelia are detectable and clinically relevant in hookah smokers.

Interferons (IFNs) constitute the first line of defense against microbial infections particularly against viruses. They provide antiviral properties to cells by inducing the expression of hundreds of genes known as interferon-stimulated genes (ISGs). The two most important IFNs that can be produced by virtually all cells in the body during intrinsic innate immune response belong to two distinct families: the type I and type III IFNs. The type I IFN receptor is ubiquitously expressed whereas the type III IFN receptor's expression is limited to epithelial cells and a subset of immune cells. While originally considered to be redundant, type III IFNs have now been shown to play a unique role in protecting mucosal surfaces against pathogen challenges. The mucosal specific functions of type III IFN do not solely rely on the restricted epithelial expression of its receptor but also on the distinct means by which type III IFN mediates its anti-pathogen functions compared to the type I IFN. In this review we first provide a general overview on IFNs and present the similarities and differences in the signal transduction pathways leading to the expression of either type I or type III IFNs. By highlighting the current state-of-knowledge of the two archetypical mucosal surfaces (e.g. the respiratory and intestinal epitheliums), we present the differences in the signaling cascades used by type I and type III IFNs to uniquely induce the expression of ISGs. We then discuss in detail the role of each IFN in controlling pathogen infections in intestinal and respiratory epithelial cells. Finally, we provide our perspective on novel concepts in the field of IFN (stochasticity, response heterogeneity, cellular polarization/differentiation and tissue microenvironment) that we believe have implications in driving the differences between type I and III IFNs and could explain the preferences for type III IFNs at mucosal surfaces. [ABSTRACT FROM AUTHOR]

Asthma, the most common chronic respiratory tract disease in children, is characterized by allergy, recurring airway obstruction and bronchospasm. The aim of the present study was to screen critical differentially expressed genes (DEGs) involved in asthma in children. Gene expression in different tissues was compared between asthmatic children and healthy control subjects in order to identify DEGs associated with asthma. Protein‑protein interaction (PPI) networks were constructed for the DEGs and weighted gene co‑expression network analysis methods were used to further determine the functional modules associated with DEGs in different tissue samples. In addition, the gene co‑expression network was constructed. Gene Ontology function analysis and pathway analysis were conducted to identify critical DEGs. The results identified numerous DEGs from the different tissue samples, including 1,662 DEGs from nasal‑epithelium tissue samples, 572 DEGs from peripheral blood (PB) samples and 146 DEGs from PB mononuclear cells samples. In the PPI network, F‑box only protein 6 (FBXO6), histone deacetylase 1 (HDAC1) and amyloid β precursor protein (APP) were hub genes and served an important role in the process of asthma. In addition, proliferating cell nuclear antigen (PCNA), integrin α‑4 (ITGA4), catenin α‑1 (CTNNA1), nuclear factor‑κB1 (NF‑κB1) and mechanistic target of rapamycin (MTOR) may be critical DEGs involved in the progression of asthma in children. These results suggested that FBXO6, HDAC1 and APP may interact with PCNA, ITGA4, CTNNA1, NF‑κB1 and mTOR in the progression of asthma in children. [ABSTRACT FROM AUTHOR]

Epithelium is considered the first barrier defense of the organism due to its contact with the environment. The respiratory epithelium is important in the innate immune response. Respiratory viruses are the leading cause of acute respiratory infections being the respiratory epithelia (RE) their primary target. These epithelial cells have the capacity to limit viral replication and to activate the immune response. RE recognize viruses through pattern recognition receptors expressed in the cell membrane or in the cytoplasm. After recognition, RE produces a variety of molecules such as defensins, nitric oxide, cytokines, chemokines, and interferons in response to viral infection. The early antiviral state by RE is crucial to control viral replication. This review analyzes the role of the RE cells as innate immunity mediator and discusses the potential use of this knowledge in the development of future mucosal therapies and vaccination. [ABSTRACT FROM AUTHOR]

Background Given the strong environmental influence on both epigenetic marks and allergic asthma in children, the epigenetic alterations in respiratory epithelia might provide insight into allergic asthma. Objective We sought to identify DNA methylation and gene expression changes associated with childhood allergic persistent asthma. Methods We compared genomic DNA methylation patterns and gene expression in African American children with persistent atopic asthma (n = 36) versus healthy control subjects (n = 36). Results were validated in an independent population of asthmatic children (n = 30) by using a shared healthy control population (n = 36) and in an independent population of white adult atopic asthmatic patients (n = 12) and control subjects (n = 12). Results We identified 186 genes with significant methylation changes, differentially methylated regions or differentially methylated probes, after adjustment for age, sex, race/ethnicity, batch effects, inflation, and multiple comparisons. Genes differentially methylated included those with established roles in asthma and atopy and genes related to extracellular matrix, immunity, cell adhesion, epigenetic regulation, and airflow obstruction. The methylation changes were substantial (median, 9.5%; range, 2.6% to 29.5%). Hypomethylated and hypermethylated genes were associated with increased and decreased gene expression, respectively ( P < 2.8 × 10 −6 for differentially methylated regions and P < 7.8 × 10 −10 for differentially methylated probes). Quantitative analysis in 53 differentially expressed genes demonstrated that 32 (60%) have significant methylation-expression relationships within 5 kb of the gene. Ten loci selected based on the relevance to asthma, magnitude of methylation change, and methylation-expression relationships were validated in an independent cohort of children with atopic asthma. Sixty-seven of 186 genes also have significant asthma-associated methylation changes in nasal epithelia of adult white asthmatic patients. Conclusions Epigenetic marks in respiratory epithelia are associated with allergic asthma and gene expression changes in inner-city children. [ABSTRACT FROM AUTHOR]

Abstract: This review presents the different pathways that nanomedicines can follow after deposition in the lung. These include their interactions with the air–liquid interface, their diffusion in and clearance with mucus, their uptake by lung-surface macrophages, their transport across respiratory epithelia and protein metabolism. These processes mostly occur simultaneously in the lung and their respective rates determine the dominant pathways followed by the particular nanomedicine. Accordingly, the fate of nanomedicines in the lung is highly dependent on the physico-chemical as well as biological properties of the compound considered. IgG are endocytosed by alveolar macrophages and transported across respiratory epithelia by receptor-mediated endocytosis while insulin is not taken up by alveolar macrophages and rapidly crosses the epithelium towards the systemic circulation via paracellular diffusion. Inhaled proteins are usually cleared from the lung within 24h. Nanoparticles largely escape uptake by lung-surface macrophages and can remain in the lung for weeks, without significant translocation across respiratory epithelia. Major recent advances: The fate of therapeutic proteins within the lungs has been partly revealed over the past 15years. Yet, many recent studies have investigated the pulmonary fate of nanoparticles and have highlighted their persistence within the lung, their low uptake by lung-surface macrophages and their limited translocation across respiratory epithelia towards the systemic circulation. [Copyright &y& Elsevier]

Adenosine is formed from extracellular purines by ecto-5′-nucleotidase (CD73) and is an essential player in allergic airway inflammation. The contribution of adenosine and other purines to electrolyte transport and mucociliary clearance was studied in airways of allergen challenged mice. No signs for allergen-induced inflammation were found in CD73−/− mice, and adenosine monophosphate (AMP) was unable to elicit airway Cl− secretion in these animals. Tracheas of ovalbumin (OVA)-treated BALB/c and CD73+/+ mice were hyperresponsive towards methacholine when assessed by Penh and direct optical measurement of contraction. In addition Cl− secretion activated by ATP and ADP was enhanced. These changes were not observed in CD73−/− mice. Expression of CFTR or CLCA was unchanged upon OVA treatment of CD73 mice, suggesting enhanced Cl− secretion due to upregulated purinergic pathways. Mucociliary clearance was determined by measuring particle transport in excised mouse tracheas and was strongly enhanced in OVA-challenged CD73+/+ mice, but remained unchanged in CD73−/− mice. While mucociliary clearance is activated by allergen exposure independent of functional ecto-5′-nucleotidase, airway inflammation is largely dependent on CD73. Thus, ecto-5′-nucleotidase may provide a novel target for therapeutic intervention, probably by local application of ecto-5′-nucleotidase inhibitors through inhalation. [ABSTRACT FROM AUTHOR]

Since there have been few investigations on the free grafting of respiratory epithelia, the aim of our present experiments was to establish whether it was possible to carry out such grafting in an animal model. Purebred strains of Lewis blood group rats were used to avoid host-versus-graft rejections of mucous membrane transferred from a donor to a recipient animal. Respiratory epithelia from the nasal septum were transplanted to the rectus abdominis muscle. Muscle and epithelial layers were then removed 4 months later. Using light and electron microscopy the function of the grafted ciliated epithelia - i.e. of the ciliated and goblet cells -could be demonstrated. These findings showed that respiratory epithelia heal when grafted onto a recipient site which has an adequate blood supply but do not lose their initial differentiation or functions. The results obtained in this experiment are important clinically for reconstruction of the respiratory tracts. [ABSTRACT FROM AUTHOR]

The effects of luminal glucose on transepithelial Na and fluid transports were investigated in rat lungs. Two preparations were used: isolated, perfused lungs and lungs in situ perfused with blood (cross-circulations), a situation more comparable to that existing in vivo. Unidirectional (efflux from air spaces, J) and net ( J) Na fluxes and fluid absorption from air spaces were estimated in lungs filled with bicarbonate-buffered solutions containing 10 mmol/l of either mannitol, glucose or α-methyl-D-glucopyranoside, or 0.1 mmol/l phlorizin in the presence of glucose. In the presence of mannitol J was estimated to be 7.8±1.02 pmol cm s in isolated lungs and 9.2±0.97 pmol cm s in lungs in situ, and J 1.0±0.33 and 2.5±0.35 pmol cm s, respectively. When glucose replaced mannitol J (+30%+40%), J (+200%+300%) and fluid absorption (+100%+400%) were enhanced in both preparations. Substituting methyl glucoside for mannitol increased Na and fluid absorption rates to the same extent as glucose. Phlorizin, in the presence of glucose, reduced Na and fluid transports to values similar to those observed in the presence of mannitol. These changes did not result from modifications of the paracellular permeabilities (assessed with [H]mannitol). It was concluded, in both isolated lungs and lungs in situ, that (a) the presence of glucose within air spaces accelerates both transepithelial Na and fluid transports, (b) increased Na transport is responsible for this larger fluid absorption, which exceeded threefold that the absorption of glucose alone would have produced, (c) most of this increase of transport rates is not the consequence of an increased glucose consumption providing a larger energy supply for ion transport, since the non-metabolizable analog methyl glucoside similarly enhanced transepithelial Na and fluid transports, and (d) the depressing effect of phlorizin on transepithelial Na transport indicates that the enhancement of Na transport by glucose is the consequence of increased Na entry across the apical membrane of respiratory epithelial cells through cotransport with glucose. It is proposed that glucose may play a role in the modulation of the epithelial lining fluid depth. [ABSTRACT FROM AUTHOR]

The present study examines the properties of Clchannels in cultured respiratory cells of cystic fibrosis (CF) patients and normal (N) individuals. In excised membrane patches the conductances for CF and N Cl channels were larger at positive as compared to negative clamp voltages ( V): 74±2.6 ( V > 0) and 47±2.0 pS ( V < 0) for CF ( n= 57) and 69±3.6 ( V > 0) and 45±2.3 pS ( V < 0) for N ( n=35). The open probability ( P) of the channel increased markedly with depolarization. Both the voltage dependence of the conductance and of P contribute to the outward rectification of the channel. The time histogram analysis reveals two open and two closed time constants. The selectivity of the channel was Cl=Br =I > NO≫ gluconate. The channel was inhibited reversibly by 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) at 10 mol/l to 10 mol/l. While Cl channels were present in cell attached patches of N cells, they were absent in those of CF cells. The mean conductance for cell attached (N) Cl channels was 76±3.2 pS for positive clamp voltages ( V) and 46±3.9 pS for negative V ( n=8). When the membrane patches were excised from CF cells Cl currents appeared spontaneously ( n=19). The immediate appearance (within 1 s) of Cl channels after excision was observed at positive ( n=6) as well as at negative clamp voltage ( n=13). 'Excision activation' of CF Cl channels was observed at low (< 10 mol/l) or high (10 mol/l) calcium activities on the cytosolic side of the excised patch. Variation of the Ca activity (< 10-10 mol/l) or pH (6.5-8.5) on the cytosolic side exerted no effects on these Cl channels. These results suggest that Cl channels are present in the apical membrane of CF and N respiratory cells but they seem to be inhibited in intact CF cells. Excision of the patch and hence removal of the cytosolic 'inhibitor' leads to an activation of Cl channels. The Cl channels in excised patches of N and CF cells have identical properties. [ABSTRACT FROM AUTHOR]

The ultrastructure of the secondary lamellae has been examined in four species of free-swimming elasmobranchs, two species of Raia and five species of bony flatfishes. Microvilli which are present on the outer epithelial surface vary in form and size. It is suggested that a possible function of the microvilli is to anchor a surface mucus covering whose possible functions are discussed. Vesicles are found immediately beneath the microvilli in elasmobranchs but not in teleosts. Chloride and mucous cells are present on the secondary lamellae of all species and often have microvilli of greater length than on the other cells of the epithelium. Micropinocytotic vesicles are found on both sides of the basement membrane. The number of columns enclosed in the pillar cells varied from 5-11. The water-blood pathway showed variations in thickness not only between different species but also in different parts of individual secondary lamellae. A general trend in the mean total thickness was found, being greater in the swimming elasmobranchs (10.22 μ) than in the rays (5.47 μ) and bony flatfish (3.59 μ). This trend is also seen in the greater length of microvilli and thickness of basement membrane in the elasmobranchs than in the teleosts. [ABSTRACT FROM AUTHOR]

The use of adult Drosophila melanogaster as a model for hematopoiesis or organismal immunity has been debated. Addressing this question, we identify an extensive reservoir of blood cells (hemocytes) at the respiratory epithelia (tracheal air sacs) of the thorax and head. Lineage tracing and functional analyses demonstrate that the majority of adult hemocytes are phagocytic macrophages (plasmatocytes) from the embryonic lineage that parallels vertebrate tissue macrophages. Surprisingly, we find no sign of adult hemocyte expansion. Instead, hemocytes play a role in relaying an innate immune response to the blood cell reservoir: through Imd signaling and the Jak/Stat pathway ligand Upd3, hemocytes act as sentinels of bacterial infection, inducing expression of the antimicrobial peptide Drosocin in respiratory epithelia and colocalizing fat body domains. Drosocin expression in turn promotes animal survival after infection. Our work identifies a multi-signal relay of organismal humoral immunity, establishing adult Drosophila as model for inter-organ immunity. • Adult Drosophila have an extensive blood cell reservoir at the respiratory epithelia • No sign of hematopoiesis in adult Drosophila , even after bacterial infection • Blood cells act as sentinels of infection via PGRP-LC/Imd/Upd3 signaling • In tissues of the reservoir, this induces Drosocin expression to promote survival Sanchez Bosch et al. study hemocytes (blood cells) in adult Drosophila. They do not find hematopoiesis in the adult system, but they do identify a major hemocyte reservoir at the respiratory epithelia and colocalizing fat body. Following bacterial infection, hemocytes relay signals to the tissues of the reservoir to mediate a protective humoral immune response. [ABSTRACT FROM AUTHOR]