Thymic stromal lymphopoietin-elicited basophil responses promote eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a food allergy-associated inflammatory disease characterized by esophageal eosinophilia. Current management strategies for EoE are nonspecific, and thus there is a need to identify specific immunological pathways that could be targeted to treat this disease. EoE is associated with polymorphisms in the gene that encodes thymic stromal lymphopoietin (TSLP), a cytokine that promotes allergic inflammation, but how TSLP might contribute to EoE disease pathogenesis has been unclear. Here, we describe a new mouse model of EoE-like disease that developed independently of IgE, but was dependent on TSLP and basophils, as targeting TSLP or basophils during the sensitization phase limited disease. Notably, therapeutic TSLP neutralization or basophil depletion also ameliorated established EoE-like disease. In human subjects with EoE, we observed elevated TSLP expression and exaggerated basophil responses in esophageal biopsies, and a gain-of-function TSLP polymorphism was associated with increased basophil responses in patients with EoE. Together, these data suggest that the TSLP-basophil axis contributes to the pathogenesis of EoE and could be therapeutically targeted to treat this disease.

Dilated intercellular spaces: a morphological feature of acid reflux--damaged human esophageal epithelium

BACKGROUND & AIMS

Dilated intercellular spaces are a sign of epithelial damage in acid-perfused rabbit esophagus, a change best identified by transmission electron microscopy. The aim of this study was to determine if this change is also a feature of acid damage to human esophageal epithelium.

METHODS

Endoscopic esophageal biopsy specimens from patients with (n = 11) and without (n = 13) recurrent heartburn were examined using transmission electron microscopy. Of 11 patients with heartburn, 6 had erosive esophagitis and 5 had normal-appearing mucosa on endoscopy; 13 controls had no symptoms or signs of esophageal disease. Using a computer, intercellular space diameter was measured from transmission electron microscopy photomicrographs of the specimen from each patient.

RESULTS

Intercellular space diameter was significantly greater in specimens from patients with heartburn than those from controls; this was true irrespective of whether the patient had erosive or nonerosive disease. Space diameters of > or = 2.4 microns were present in 8 of 11 patients with heartburn and in no controls.

CONCLUSIONS

Dilated intercellular spaces are a feature of reflux damage to human esophageal epithelium. As a morphological marker of increased paracellular permeability, its presence in patients without endoscopic abnormalities may help explain their development of heartburn.

Inflammatory myofibroblastic tumor (plasma cell granuloma). Clinicopathologic study of 20 cases with immunohistochemical and ultrastructural observations

Twenty cases of inflammatory myofibroblastic tumor (IMT) were studied; 19 involved the lung and 1 the esophagus only. The patients' ages ranged from 3 to 72 years. There were 9 males and 11 females. Involvement of a bronchus was seen in one case and of mediastinal structures in four. Chest pain and dyspnea were common symptoms; eight patients were asymptomatic. Seven patients underwent lobectomy, 12 local excision, and 1 biopsy alone. The lesions were nonencapsulated and ranged from 1.2 to 15 cm. Various proportions of plasma cells, histiocytes, and spindle cells were observed; the latter corresponded ultrastructurally to fibroblasts and myofibroblasts, were immunoreactive for vimentin and actin and focally for desmin, and were negative for epithelial markers. Plasma cells were polyclonal for light chains. One patient had two recurrences, and in one case a large pleural IMT was found eight years after the excision of a similar lesion in the lung. All patients with follow-up (ten) were well as long as ten years after the diagnosis (average, 3.7 years).

Evaluation of oesophageal mucosa integrity by the intraluminal impedance technique

BACKGROUND

Oesophageal intraluminal impedance is currently used for assessment of reflux in gastro-oesophageal reflux disease (GORD). Oesophageal mucosa integrity may have a key role in heartburn perception in non-erosive reflux disease (NERD). Severe erosive oesophagitis is associated with low impedance baseline. We hypothesised that impedance baseline measurements could be used to evaluate changes in oesophageal mucosa integrity in man.

METHODS

We measured oesophageal impedance baseline before, during and after acid perfusion in rabbits and healthy subjects. Transepithelial resistance (TER) was determined and dilated intercellular spaces (DIS) were assessed in isolated rabbit oesophageal mucosa. Impedance baseline was measured retrospectively at different levels of the oesophagus in impedance-pH recordings from asymptomatic volunteers and patients with GORD.

RESULTS

In healthy subjects and rabbits, impedance baseline dropped dramatically during perfusion of control solution (pH 7.2) but after perfusion, impedance recovered. In rabbits, after perfusion with saline pH 1.5 and 1.0 impedance values remained a 39.1 ± 7.0% and 63.9 ± 6.5% (p < 0.05) lower respectively. There was a positive correlation between in vivo basal impedance and in vitro TER values (r = 0.72, p = 0.0021). Tissue showed no erosions but both acidic solutions induced DIS. In healthy subjects, after perfusion with saline pH 2.0 and 1.0 the impedance baseline remained lower a 21.9 ± 6.5% and 52.7 ± 5.0%, (p < 0.0001) respectively. Patients with GORD have a lower impedance baseline than healthy volunteers at the distal oesophagus.

CONCLUSIONS

Impedance baseline measurements might be used to evaluate the status of the oesophageal mucosa and to study the role of the impaired mucosal integrity in acid-induced heartburn in healthy volunteers and in patients with GORD.

Membrane alterations during cornification of mammalian squamous epithelia: a freeze-fracture, tracer, and thin-section study

Tight junctions (zonulae occludentes) create a pericellular barrier to the diffusion of large molecules in non-keratinizing mammalian epithelia. However, in cornifying epithelia such as the epidermis, the importance of tight-junctional elements versus secreted intercellular lipid for barrier function is uncertain. In an attempt to resolve this question, we compared membrane structure in the stratum granulosum and stratum corneum of epidermis, esophagus, and vagina of newborn and adult humans and mice under both normal and various experimental conditions. We incubated pieces of epidermis in organ culture and infused tissues with lanthanum or horseradish peroxidase in vivo and in vitro. All were processed for electron microscopy of freeze-fracture replicas or thin sections. Lanthanum seeped outward to the stratum granulosum in all tissues examined--further apical migration was halted by lamellar-body contents in skin. A similar pattern of intercellular lamellar lipid deposition and membrane structure occurred in all epithelia studied. Freeze-fracture replicas of these obstructive regions revealed occasional, incomplete junctional strands (particularly in moist epithelia) and abundant lamellar material, but complete zonulae occludentes were never encountered. A possible relationship between moisture and tight junction formation was further suggested by organ culture experiments during which brief incubations stimulated an increase in the number of junctional strands and diminished numbers of lamellar bodies. We conclude that, in the epithelia studied, the deposition of secreted lamellar body contents forms the barrier to water-soluble tracer loss: tight-junctional elements are either absent or too fragmentary to constitute an effective barrier.

Sensory vagal innervation of the rat esophagus and cardia: a light and electron microscopic anterograde tracing study

Wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) was injected into nodose ganglia of rats. In the esophagus and cardia, dense networks of anterogradely labeled fibers and beaded terminal-like arborisations were observed around myenteric ganglia after combined histochemistry for HRP and acetylcholinesterase. The muscularis externa and interna proper were free of label except for a few traversing fibers. Submucosal and mucosal labeling was rather sparse except for the most oral part of the esophagus, where a dense mucosal innervation was found. Control experiments including WGA-HRP injections into the cervical vagus nerve, nodose ganglion injections after supranodose vagotomy, and anterograde [3H]leucine tracing from the nodose ganglion indicated that all labeled fibers in the esophagus and cardia originated from sensory neurons in the nodose ganglion. Electron microscopy revealed that labeled vagal sensory terminals related to myenteric ganglia were mostly large, mitochondria-rich profiles located predominantly on the surface of the ganglia. Specialized membrane contacts connected sensory terminals with other unlabeled profiles possibly derived from intrinsic neurons. The polarity of these contacts suggested the vagal sensory terminals to be presynaptic to intrinsic neurons of the myenteric ganglia. A hypothesis is formulated postulating a mechanoreceptive role for 'myenteric' vagal sensory terminals, providing both the brainstem (via the vagus nerve) and, by synaptic action upon intrinsic neurons, the myenteric plexus with information on tension and motility of the esophagus and cardia.

Critical role of stress in increased oesophageal mucosa permeability and dilated intercellular spaces

BACKGROUND

In patients with non-erosive gastroesophageal reflux disease, heartburn can occur when acid reaches sensory nerve endings through oesophageal-mucosa-dilated intercellular spaces. Stressful life events may increase heartburn perception. In the rat, acute stress increases gastric and intestinal mucosa permeability. We investigated whether acute stress can also increase oesophageal mucosa permeability and contribute to the dilation of mucosa intercellular spaces.

METHODS

Male Sprague-Dawley rats were submitted to partial restraint stress. Oesophageal mucosa from stressed and control rats was mounted in diffusion chambers. The permeability to (51)Cr-EDTA (400 Da), fluorescein isothiocyanate (FITC)-dextran 4000 Da (FD4) and FITC-dextran 20 000 Da (FD20) was assessed after tissue incubation either with Krebs (control) or HCl pH 2.0+ pepsin 1 mg/ml. The diameter of intercellular spaces was assessed using transmission electron microscopy.

RESULTS

Acute stress increased faecal output, small-intestinal permeability and glycaemia. Exposure of oesophageal mucosa from control rats to acid-pepsin did not increase permeability to any of the tested molecules. Stress increased the number of submucosal mast cells and, by itself, increased the permeability to the smallest molecule (22.8+/-7.1 pmol/cm(2) vs 5.8+/-2.1 pmol/cm(2)) (p<0.001). Exposure of mucosa from stressed rats to acid-pepsin significantly increased permeability to all molecules tested. Electron microscopy showed dilated intercellular spaces only in mucosa from stressed rats (with and without exposure to acid-pepsin).

CONCLUSIONS

Acute stress can increase, by itself, oesophageal mucosa permeability. There is a potentiation between stress and exposure of the oesophageal mucosa to acid-pepsin, leading to increased permeability and dilated intercellular spaces.

Functional significance of the variations in the geometrical organization of tight junction networks

Using freeze-fracture techniques, we have examined the morpholog of tight junction networks found along the length of the alimentary tract of Xenopus laevis before and after metamorphosis. We have developed the hypothesis, based on these observations, that the geometrical organization of the network determined by the stress-induced shape changes normally experienced by the cells linked by the network. Consistent with this theory, tight junctions can be classified into two distinct types of network organization which differ in their response normal and experimentally induced stress conditions: (a) loosely interconnected networks which can stretch or compress extensively under tension, thereby adapting to stress changes in the tissue; and (b) evenly cross-linked networks which retain their basic morphology under normal stress conditions. The absorptive cells of the large intestine as well as the mucous cells of the gastrointestine or stomach are sealed by the first, flexible type of tight junction. The second type of junctional organization, the evenly cross-connected network, is found between absorptive cells of the small intestine and ciliated cells of the esophagus, and reflects in its constant morphology the relative stability of the apical region of both of these cell types. Networks intermediate between these two types arise when a cell which would normally form a lossely interconnected network borders a cell which tends to form a more evenly cross-linked network, as is found in the esophagus where ciliated and goblet cells adjoin. Despite the change in the animal's diet during metamorphosis from herbivorous to carnivorous, the basic gemetrical organization of the networks associated with each tissue of the alimentary tract remains the same.

Colonization of the porcine gastrointestinal tract by lactobacilli

Eight strains of lactobacillus isolated from the porcine gastrointestinal tract were tested for their ability to adhere in vitro to cells collected from stratified squamous epithelium in the digestive tracts of newborn piglets. Piglets were inoculated with individual strains, and their digestive tracts were sampled at intervals to determine the colonizing ability of the lactobacilli. The results of the in vitro test did not predict whether a lactobacillus strain would associate with stratified squamous epithelium in the piglet digestive tract, but epithelial association in vivo appeared to be an important factor in the maintenance of lactobacillus populations in the tract. None of the lactobacillus strains used as inocula was numerically dominant in the tract 7 days after inoculation of the piglets with a single dose of the bacteria.

The experimental replacement of a cervical esophageal segment with an artificial prosthesis with the use of collagen matrix and a silicone stent

OBJECTIVE

Attempts have been made to replace esophageal defects with a variety of artificial materials. However, because of the artificial nature of the materials, problems such as infection, leakage, stricture, or dislocation could not be avoided. Therefore we have designed a new type of artificial esophagus that is gradually replaced by host tissue.

METHODS

Our artificial esophagus was a two-layered tube consisting of a collagen sponge matrix and an inner silicone stent. We used it to replace 5 cm esophageal segmental defects in 43 dogs, and the inner silicone stent was removed endoscopically at weekly intervals from 2 to 4 weeks.

RESULTS

In the 27 dogs from which the silicone stent was removed at 2 or 3 weeks, constriction of the regenerated esophagus progressed and the dogs became unable to swallow within 6 months. In the 16 dogs from which the silicone stent was removed at 4 weeks, highly regenerated esophageal tissue successfully replaced the defect, leaving no foreign body in the host. Moreover, the regenerated esophagi had stratified flattened epithelia, striated muscle tissue composed of an inner circular and an outer longitudinal muscle layer, and esophageal glands.

CONCLUSIONS

Even in mature adult higher mammals, esophageal high-order structures can be regenerated provided that an adequate three-dimensional extracellular structure is put in place for a sufficient period.

A proposed function for microridges on epithelial cells

Microridges (MR), also called microvillar ridges, microplicae and cytoplasmic folds, have been noted on many epithelial surfaces. Several functions have been proposed for these structures. In the present study we examine the mechanical role that microridges may play in holding mucus to the lumenal surface to the esophagus in the trout Salmo gairdneri. Our findings support the hypothesis that the microridges help hold a protective coat of mucus to the epithelium. In addition, the complex curved or whorled arrangement of microridges appears to facilitate the spread of mucus away from goblet cells.

Expression of specific keratin markers by rabbit corneal, conjunctival, and esophageal epithelia during vitamin A deficiency

Using an in vivo rabbit model system, we have studied the morphological and biochemical changes in corneal, conjunctival, and esophageal epithelia during vitamin A deficiency. Light and electron microscopy showed that the three epithelia undergo different degrees of morphological keratinization. Corneal and conjunctival epithelia became heavily keratinized, forming multiple layers of superficial, anucleated cornified cells. In contrast, esophageal epithelium underwent only minor morphological changes. To correlate morphological alterations with the expression of specific keratin molecules, we have analyzed the keratins from these epithelia by the immunoblot technique using the subfamily-specific AE1 and AE3 monoclonal antikeratin antibodies. The results indicate that during vitamin A deficiency, all three epithelia express an AE1-reactive, acidic 56.5-kd keratin and an AE3-reactive, basic 65-67-kd keratin. Furthermore, the expression of these two keratins correlated roughly with the degree of morphological keratinization. AE2 antibody (specific for the 56.5- and 65-67-kd keratins) stained keratinized corneal epithelial sections suprabasally, as in the epidermis, suggesting that these two keratins are expressed mainly during advanced stages of keratinization. These two keratins have previously been suggested to represent markers for epidermal keratinization. Our present data indicate that they can also be expressed by other stratified epithelia during vitamin A deficiency-induced keratinization, and suggest the possibility that they may play a role in the formation of the densely packed tonofilament bundles in cornified cells of keratinized tissues.

Altered intercellular glycoconjugates and dilated intercellular spaces of esophageal epithelium in reflux disease

BACKGROUND AND AIMS

The usefulness of histological diagnosis of gastroesophageal reflux disease (GERD) is limited by poor specificity or sensitivity of available diagnostic tools. Recently, ultrastructural morphometry showed interstitial space dilation (ISD) to be a reliable sign of reflux disease. Aims of this study were to (a) search for a light microscopy equivalent of ISD, (b) test its diagnostic value, and (c) look for a possible role of intercellular glycoconjugates in its genesis.

METHODS

Esophageal grasp biopsies were taken during endoscopy, 2-3 cm and 6-7 cm above the squamocolumnar junction, from patients under investigation for GERD symptoms. The biopsies were fixed in aldehyde solutions and embedded in resin for electron microscopy or in paraffin for routine histology, and the glycoconjugates underwent immunohistochemistry using 3-fucosyl-N-acetylactosamine antibodies.

RESULTS

Irregular intercellular space dilation was detected in the basal and prickle layers using both light and electron microscopy. Hematoxylin-eosin preparations showed ISD in 20 of 22 (90%) erosive esophagitis cases, 30 of 44 (68%) endoscopy negative GERD cases, and 1 of 12 (8%) controls, with good interobserver (K = 0.75) and bioptic site reproducibility. ISD correlated with loss or rearrangement of intercellular glycoconjugates of the overlying layers and with granulocyte (eosinophil and/or neutrophil) infiltration.

CONCLUSIONS

Light microscopy ISD is a suitable index of GERD. Alterations of intercellular glycoconjugates are likely to have a role in the genesis of ISD and GERD.

Development of an esophagus acellular matrix tissue scaffold

A cell-extraction protocol yielding an esophagus acellular matrix (EAM) scaffold for use in tissue engineering of an esophagus, including hypotonic lysis, multiple detergent cell extraction steps, and nucleic acid digestion, was developed in a rat model. Histological techniques, burst pressure studies, in vitro esophageal epithelial cell seeding, and in vivo implantation were used to assess cell extraction, extracellular matrix (ECM) preservation, and biocompatibility. Microscopy demonstrated that cell extraction protocols using sodium dodecyl sulfate (SDS) (0.5%, wt/vol) as a detergent resulted in cell-free EAM with retained ECM protein collagen, elastin, laminin, and fibronectin. Burst pressure studies indicated a loss of tensile strength in EAMs, but at intraluminal pressures that were unlikely to affect in vivo application. In vitro cell seeding studies exhibited epithelial cell proliferation with stratification similar to native esophagi after 11 days, and subcutaneously implanted EAMs displayed neovascularization and a minimal inflammatory response after 30 days of implantation. This study presents an esophagus acellular matrix tissue scaffold with preserved ECM proteins, biomechanical properties, and the ability to support esophageal cell proliferation to serve as the foundation for a tissue-engineered esophagus.

Four-hour processing of clinical/diagnostic specimens for electron microscopy using microwave technique

A protocol for routine 4-hour microwave tissue processing of clinical or other samples for electron microscopy was developed. Specimens are processed by using a temperature-restrictive probe that can be set to automatically cycle the magnetron to maintain any designated temperature restriction (temperature maximum). In addition, specimen processing during fixation is performed in 1.7-ml microcentrifuge tubes followed by subsequent processing in flow-through baskets. Quality control is made possible during each step through the addition of an RS232 port to the microwave, allowing direct connection of the microwave oven to any personal computer. The software provided with the temperature probe enables the user to monitor time and temperature on a real-time basis. Tissue specimens, goat placenta, mouse liver, mouse kidney, and deer esophagus were processed by conventional and microwave techniques in this study. In all instances, the results for the microwave-processed samples were equal to or better than those achieved by routine processing techniques.

Chronic acid exposure leads to activation of the cdx2 intestinal homeobox gene in a long-term culture of mouse esophageal keratinocytes

To explore mechanisms whereby Malpighian keratinocytes can transdifferentiate into an intestinal-like epithelium, as observed in the early steps of Barrett's esophagus (BE) development, long-standing cultures of esophageal keratinocytes derived from normal mouse esophageal explants were developed. These cells were able to form multilayers and to differentiate on filter support by the formation of differentiated layers of basal cells (cytokeratine 14 positive) on which secondary suprabasal cell layers (cytokeratine 4 positive) spontaneously developed. Thus, these cultured cells, referred to as P3E6, reproduced, at least in part, the proliferation and stratification pattern existing in the normal esophagus. Because chronic exposure to acid pH is known to be a critical factor for BE development, culture medium at pH 3.5 was added into the apical chamber of cell cultures. This led to a decrease in the overall number of cells but it did not affect cell proliferation. Furthermore, external acid environment triggered expression of the GFP reporter gene fused downstream of the cdx2 intestinal homeogene regulatory sequences in P3E6 transfected cells. Expression of the endogenous CDX2 protein, detected by western blot and immunocytochemical analysis, correlated with promoter activation. These findings demonstrate that chronic exposure of esophageal keratinocytes to acid pH induces transcription of cdx2, an intestinal specific homeobox gene known to play a critical role in the differentiation and maintenance of intestinal epithelial functions. The results suggest that chronic acid exposure can modify the fate of P3E6 esophageal keratinocytes towards an intestinal program. This can be a key step in the development of intestinal metaplasia often observed in esophagus-cardia junction.

Microplicae: characteristic ridge-like folds of the plasmalemma

Scanning electron microscopy reveals that the free surfaces of stratified squamous epithelial cells lining the alimentary tract, cornea, and conjunctiva exhibit characteristic ridge-like folds of plasmalemma. These microplicae are approximately 0.1-0.2 micronm in width, of variable height (0.2-0.8 micronm) and length, may followstraight or winding paths, often branch, and exhibit a wide variety of patterns over the surfaces of cells. Transmission electron microscopy reveals that microplicae often have a fine (100-150 A) electron-dense zone subjacent to their plasmalemma and an intracellular matrix characterized by a disorderly arrary of fine filaments (40-60 A in diameter). Microplicae appear to arise from plasmalemmal fold which once provided for intercellular interdigitation and desmosome abhesion between adjacent cells. Ruthenium red staining demonstrates that microplicae and interplical grooves are covered with a polyanionic glycocalyx. Although free surface microplicae may merely represent the renmants of intercellular interdigitations or a modified expression of microvillous-like extensions, it is also possible that they serve another specific function. In this regard it is speculated that microplical and interplical grooves may function to hold a layer of lubricating and cushioning mucin designed to protect the underlying plasmalemma from abrasive abuse.

Detection by scanning electron microscopy of a distinctive esophageal surface cell at the junction of squamous and Barrett's epithelium

Metaplastic columnar epithelium replaces the normal squamous epithelium in Barrett's esophagus. We characterized the surface epithelial cells of the junction between squamous and Barrett's epithelium using scanning electron microscopy and light microscopy. In four biopsy specimens from the squamous-Barrett's junction in three patients, we found a distinctive cell type having features intermediate between those of squamous and columnar epithelium. Its distinguishing characteristic is the presence on its surface of two disparate structures not normally present on the same cell in the gastrointestinal tract: microvilli (a scanning electron microscopy feature of glandular epithelium) and intercellular ridges (a scanning electron microscopy feature of squamous mucosa). The surface characteristics of this newly recognized cell were strikingly similar to those of cells found in the transformation zone of the uterine cervix, an area in which squamous epithelium physiologically replaces columnar epithelium. We also examined 28 biopsies of the gastroesophageal junction area from 14 patients with and without a history of heartburn but with no evidence of Barrett's esophagus. None of these biopsies showed the distinctive cell. We hypothesize that this distinctive cell represents an intermediate step in either the development or the healing of Barrett's epithelium, during which surface characteristics of two different cell types, columnar and squamous, coexist on the same cell.

Barriers to paracellular permeability in rabbit esophageal epithelium

Morphological and electrophysiological techniques were used to define the location and nature of the barriers to diffusion across the intercellular space (paracellular pathway) of rabbit esophageal epithelium. Transmission electron microscopy and light microscopy coupled with histochemistry identified a series of tight junctions and an intercellular material staining positively for neutral and acidic glycoconjugates as likely barrier candidates. Additional studies with lanthanum and horseradish peroxidase showed that the barrier to diffusion of tracers was present throughout the stratum corneum and extended to the upper three to seven layers of stratum spinosum and that these findings were most compatible with the presence of the intercellular glycoconjugate material but not the tight junctions. Further positive staining for carbohydrate moieties at the electron microscopic level with periodic acid-thiocarbohydrazide-silver proteinate suggested that the glycoconjugate material was synthesized in the cells of the barrier layers and packaged in intracellular membrane-bound vesicles before secretion into the intercellular space. Although tight junctions were present in series within stratum corneum and, less commonly, extended to two to three cell layers of upper stratum spinosum, analysis of tracer studies, freeze-fracture replicas, electrophysiological data, and mannitol fluxes, while not conclusive, provided little to support a major role for these junctions in barrier function in this tissue.

Role of calcium and calmodulin in ciliary stimulation induced by acetylcholine

The goal of this work was to elucidate the molecular events underlying stimulation of ciliary beat frequency (CBF) induced by acetylcholine (ACh) in frog esophagus epithelium. ACh induces a profound increase in CBF and in intracellular Ca(2+) concentration ([Ca(2+)](i)) through M(1) and M(3) muscarinic receptors. The [Ca(2+)](i) slowly decays to the basal level, while CBF stabilizes at an elevated level. These results suggest that ACh triggers Ca(2+)-correlated and -uncorrelated modes of ciliary stimulation. ACh response is abolished by the phospholipase C (PLC) inhibitor U-73122 and by depletion of intracellular Ca(2+) stores but is unaffected by reduction of extracellular Ca(2+) concentration and by blockers of Ca(2+) influx. Therefore, ACh activates PLC and mobilizes Ca(2+) solely from intracellular stores. The calmodulin inhibitors W-7 and calmidazolium attenuate the ACh-induced increase in [Ca(2+)](i) but completely abolish the elevation in CBF. Therefore, elevation of [Ca(2+)](i) is necessary for CBF enhancement but does not lead directly to it. The combined effect of Ca(2+) elevation and of additional factors, presumably mobilized by Ca(2+)-calmodulin, results in a robust CBF enhancement.

Effects of bile acids and hydrogen ion on the fine structure of oesophageal epithelium

Oesophageal mucosal biopsies were incubated in 20, 0, and 0.2mM solutions of cholic, chenodeoxycholic, ursodeoxycholic, and deoxycholic bile acids. Both conjugated and unconjugated bile acids were studied at pH 1 and 7 singly and in combination. Observations were also made using 0.1 N hydrochloric acid and human gastric juice at pH 1-3 and 7-8. After incubation for up to 15 minutes the mucosa was examined under transmission electron microscopy. We concluded that high and moderate concentration of all the common bile acids damaged the oesophagus irrespective of the pH, that low concentrations of bile acids were damaging only at high acid levels, and that damage to the epithelium did not occur when the pH of the gastric juice had been raised.

Epidermolysis bullosa acquisita and inflammatory bowel disease

Immunologic studies on lesional and nonlesional "normal" -appearing skin of a 32-year-old man with epidermolysis bullosa acquisita (EBA) revealed the following: (1) Noninflammatory subepidermal bullae formation in the periodic acid-Schiff (PAS)-positive basement membrane; (2) linear deposits of polyclonal IgG, Clq, C4, C3, properdin, and factor B at the dermoepidermal junction; IgA and IgM were not found; (3) broad subbasal lamina electron-dense amorphous material (EDAM) lacking amyloid features by electron microscopy; EDAM was not associated with anchoring fibers; (4) cleavage plane below the EDAM. Gastrointestinal endoscopy showed inflammatory erosions in the duodenum. Microscopy of the involved duodenum showed a mixed inflammatory infiltrate, subepithelial edema, microvesiculation, and granular deposits of IgG and C3, but no EDAM. However, EDAM and immune reactants were found in the esophagus. EBA is a distinct entity characterized by the presence and location of EDAM ultrastructurally, and it may represent a gastrointestinal-cutaneous syndrome with an immune pathogenesis.

Different polypeptides form the intermediate filaments in bovine hoof and esophageal epithelium and in aortic endothelium

Polypeptides that form 10-nm filaments in vitro were isolated from three different bovine tissues: the viable portion of the hoof epithelium, the epithelium of the esophagus, and cultured endothelial cells derived from aorta. The seven polypeptides from hoof, the two from esophagus, and the one from endothelial cells were different with respect to mobility in SDS polyacrylamide gels and/or limited proteolytic digestion. Peptide maps of the different filament-forming polypeptides (FFP's) showed that none of the smaller FFP's was a fragment of any of the larger FFP's. Several isomobile fragments were found in the peptide maps of different FFP's, suggesting that they might contain regions of amino acid sequence homology. We present a hypothesis that suggests how the different 10-nm filament-forming proteins may be related.

Ectopic Cdx2 expression in murine esophagus models an intermediate stage in the emergence of Barrett's esophagus

Barrett's esophagus (BE) is an intestinal metaplasia that occurs in the setting of chronic acid and bile reflux and is associated with a risk for adenocarcinoma. Expression of intestine-specific transcription factors in the esophagus likely contributes to metaplasia development. Our objective was to explore the effects of an intestine-specific transcription factor when expressed in the mouse esophageal epithelium. Transgenic mice were derived in which the transcription factor Cdx2 is expressed in squamous epithelium using the murine Keratin-14 gene promoter. Effects of the transgene upon cell proliferation and differentiation, gene expression, and barrier integrity were explored. K14-Cdx2 mice express the Cdx2 transgene in esophageal squamous tissues. Cdx2 expression was associated with reduced basal epithelial cell proliferation and altered cell morphology. Ultrastructurally two changes were noted. Cdx2 expression was associated with dilated space between the basal cells and diminished cell-cell adhesion caused by reduced Desmocollin-3 mRNA and protein expression. This compromised epithelial barrier function, as the measured trans-epithelial electrical resistance (TEER) of the K14-Cdx2 epithelium was significantly reduced compared to controls (1189 Ohm*cm(2) ±343.5 to 508 Ohm*cm(2)±92.48, p = 0.0532). Secondly, basal cells with features of a transitional cell type, intermediate between keratinocytes and columnar Barrett's epithelial cells, were observed. These cells had reduced keratin bundles and increased endoplasmic reticulum levels, suggesting the adoption of secretory-cell features. Moreover, at the ultrastructural level they resembled "Distinctive" cells associated with multilayered epithelium. Treatment of the K14-Cdx2 mice with 5'-Azacytidine elicited expression of BE-associated genes including Cdx1, Krt18, and Slc26a3/Dra, suggesting the phenotype could be advanced under certain conditions. We conclude that ectopic Cdx2 expression in keratinocytes alters cell proliferation, barrier function, and differentiation. These altered cells represent a transitional cell type between normal squamous and columnar BE cells. The K14-Cdx2 mice represent a useful model to study progression from squamous epithelium to BE.

Electron microscopic changes in human oesophageal epithelium in oesophagitis

At the ultrastructural level the inflamed oesophageal epithelium shows a variety of lesions. These include mitochondrial damage, intracellular oedema, membrane whorls and dilation of the endoplasmic reticulum and the appearance of keratohyaline and parakeratosis granules. The basement membrane shows changes ranging from thickening to areas of loss of continuity. There is an increase in the anchoring fibrils. The spaces between the cells are enlarged and contain varying amounts of debris rich in neutral mucosubstances. There are less membrane-coated granules in the inflamed epithelium than in the normal. The intra-epithelial intrusive cells demonstrated were lymphocytes and neutrophil polymorphs.