Lectin histochemistry of the esophagus in several mammalian species

[Determination of hyperregeneratory esophagopathy in dogs with clinical signs attributable to esophageal disease]

OBJECTIVE

It was hypothesized that typical characteristics of hyperregeneratory esophagopathy (HRE) in humans such as basal cell hyperplasia and elongation of stromal papillae are also histologically detectable in canine esophageal epithelium, and that these changes are associated with clinical signs and endoscopic findings suggesting gastroesophageal reflux (GER).

MATERIAL AND METHODS

Sixty-five adult dogs with clinical signs attributable to esophageal disease underwent esophagoscopy and biopsy. Clinical signs suggesting GER (regurgitation, ptyalism, painful discomfort) were prospectively evaluated through a questionnaire. Endoscopic mucosal alterations suggesting GER such as minimal endoscopic changes and obvious mucosal defects were assessed via video endoscopy. Biopsy specimens obtained from the esophageal squamous epithelium were evaluated histologically. The squamous epithelium's substructures of esophageal biopsies were quantitatively assessed through microscopic morphometry.

RESULTS

Esophageal squamous epithelium was considered normal in 48 dogs, and HRE was detected histologically in 17 dogs; both pathognomonic changes (basal cell hyperplasia, elongation of stromal papillae) were consistently present. Morphometrically assessed stromal papillary length and basal cell layer thickness was significantly (each, p < 0.0001) higher in the 17 dogs with HRE than in the 48 dogs without HRE, respectively. Overall, clinical signs suggesting GER were significantly (p = 0.02) more frequently encountered and regurgitation was significantly (p = 0.009) more common in the 17 dogs with HRE than in the 48 dogs without HRE. Similarly, endoscopic changes were significantly (p = 0.002) more frequently observed and minimal endoscopic changes suggesting GER were significantly (p = 0.004) more common in 17 dogs with HRE than in the 48 dogs without HRE.

CONCLUSION AND CLINICAL RELEVANCE

Typical characteristics of hyperregeneratory esophagopathy in humans are also histologically detectable in canine esophageal epithelium. Histological changes are associated with clinical signs and endoscopic findings suggesting GER.

Histological and histochemical analysis of the gastrointestinal tract of the common pipistrelle bat (Pipistrellus pipistrellus)

Bats have a very high mass-specific energy demand due to small size and active flight. European bat species are mostly insectivorous and the morphology of the gastrointestinal tract should be adapted accordingly. This study investigated the general anatomy by histology and the function by analysing carbohydrate distribution in particular of the mucus of the GI tract of the insectivorous bat Pipistrellus pipistrellus. The GI tracts of three individuals were dissected, fixed in formaldehyde, and embedded in paraffin wax. The tissues and cells of the GI tract of P. pipistrellus were analysed by classical (Acid Alizarin Blue, Haematoxylin-Eosin, and Masson Goldner Trichrome), histochemical (periodic acid-Schiff, Alcian blue at pH 2.5) and lectin histochemical (lectins WGA and HPA) staining procedures. The GI tract of P. pipistrellus was organised into the typical mammalian layers. The short, narrow, and thin-walled esophagus was simple with a folded stratified squamous epithelium without glands but mucous surface cells secreting neutral mucus. The stomach was globular shaped without specialisation. Mucous surface cells produced neutral mucus whereas neck and parietal cells secreted a mixture of neutral and acid mucus. Chief cell surface was positive for N-acetylglucosamine and the cytoplasm for N-acetylgalactosamine residues. The intestine lacked a caecum and appendix. The small intestine was divided into duodenum, jejunum‑ileum and ileum‑colon. The epithelium consisted of columnar enterocytes and goblet cells. The large intestine was short, only represented by the descending colon-rectum. It lacked villi and the mucosa had only crypts of Lieberkühn. Towards the colon-rectum, goblet cells produced mucus with N-acetylglucosamine residues increasing in acidity except in colon-rectum where acidity was highest in the base of crypts. Along the tube the surface of enterocytes was positive for N-acetylglucosamine and N-acetylgalactosamine. All over the mucus filling the lumen of the GI tract was positive for N-acetylglucosamine and increased in acidity in all parts except of the stomach. In conclusion, the simple GI tract showed an anatomical reduction of tissue enabling for a short retention time and a reduction of the load carried during flight: short GI tract, lack of lymphoid tissue, missing of glands in certain regions, and a distinct pattern of mucus distribution, indicating different physiological functions of these areas. The GI tract of P. pipistrellus was typical for an insectivorous species probably representing the ancestral condition.

What is the role of endoscopy and oesophageal biopsies in the management of GERD?

Gastroesophageal reflux disease (GERD) is a diagnosis applicable to "all individuals who are exposed to the risk of physical complications from gastroesophageal reflux, or who experience clinically significant impairment of health related well being (quality of life) due to reflux related symptoms, after adequate reassurance of the benign nature of their symptoms". It remains, predominantly, a symptom-based diagnosis, confirmed clinically by a response to acid suppression therapy although it is accompanied by demonstrable increases in acid exposure on esophageal pH-metry and by endoscopic and histological changes. Standard white light endoscopy permits diagnosis of erosive reflux disease (ERD) which, if present, should be graded for severity using the Los Angeles classification system. However, the role of endoscopy in clinical practice is, primarily, to evaluate patients with persistent symptoms, despite medical therapy, or to investigate alarm features and exclude complications such as Barrett' oesophagus which should be assessed using the Prague C & M criteria. Newer endoscopic techniques allow detection of 'minimal change' GERD lesions and Barrett's oesophagus-associated dysplastic or neoplastic lesions; however, none of the newer techniques has been validated for routine clinical practice. There is an increasing recognition that histology in GERD may provide useful diagnostic information, in part to exclude other lesions, such as eosinophilic oesophagitis, intestinal metaplasia and dysplasia or malignancy and, in part, to identify changes, such as basal cell hyperplasia, papillary elongation and, most recently, dilated intercellular spaces, that are consistent with GERD. However, more widespread incorporation of histology into the clinical management of GERD will require a standardized biopsy protocol and efforts to minimise interobserver differences in the identification of GERD-related histological changes.

Early diagnostic biomarkers for esophageal adenocarcinoma--the current state of play

Esophageal adenocarcinoma (EAC) is one of the two most common types of esophageal cancer with alarming increase in incidence and very poor prognosis. Aiming to detect EAC early, currently high-risk patients are monitored using an endoscopic-biopsy approach. However, this approach is prone to sampling error and interobserver variability. Diagnostic tissue biomarkers related to genomic and cell-cycle abnormalities have shown promising results, although with current technology these tests are difficult to implement in the screening of high-risk patients for early neoplastic changes. Differential miRNA profiles and aberrant protein glycosylation in tissue samples have been reported to improve performance of existing tissue-based diagnostic biomarkers. In contrast to tissue biomarkers, circulating biomarkers are more amenable to population-screening strategies, due to the ease and low cost of testing. Studies have already shown altered circulating glycans and DNA methylation in BE/EAC, whereas disease-associated changes in circulating miRNA remain to be determined. Future research should focus on identification and validation of these circulating biomarkers in large-scale trials to develop in vitro diagnostic tools to screen population at risk for EAC development.

Histochemical features of the Muscovy duck small intestine during development

We demonstrated for the first time the distribution and morphology of argyrophil and of goblet cells in the mucosa of the small intestine of the Muscovy duck during development using the Grimelius silver staining and alcian blue/periodic acid-Schiff (AB/PAS) staining technique. The argyrophil cells distribution was variable over the length of the small intestine from embryonic day 24 (24E) to post-hatching day 13 (13d). In the villi most argyrophil cells belonged to the open-type, while in the crypts they belonged to the closed-type. In the duodenum the density of argyrophil cells was highest at hatching, while in the jejunum and in the ileum the highest density value was at hatching and 13d. AB/PAS-positive goblet cells appeared on the villi and crypts of the duodenum and jejunum at 30E, and in the ileum at hatching. The density of AB/PAS-positive cells was the highest in the three segments at hatching. The AB-positive cells, compared with the PAS-positive cells, predominated in villi and crypts of the three segments, moreover the rate of AB-positive cells to PAS-positive cells significantly decreased from 30E to 9d. An increase in argyrophil and goblet cells number during the later incubation and at hatching, could indicate the small intestine in that period is being prepared to face a new diet.

Contribution of histology to the diagnosis of reflux disease

Histology in reflux disease is still regarded as having low sensitivity and specificity. During the last three decades several histological parameters have been developed, including thickness of basal cell layer, length of epithelial papillae, intraepithelial inflammatory cells and dilation of intercellular spaces. Unfortunately classification of these parameters was often not related to the clinical symptoms of the reflux affected individuals, proper control subjects were often missing and often no interobserver variation was given. Another reason for the proposed low value of biopsies is the fact that biopsies were often taken in a non-standardised way. Recent studies point towards an area of predominantly epithelial damage close to the lesser curvature or around the right oesophageal wall. In parallel, some large, careful studies carried out recently showed a good correlation with the clinical picture of reflux disease due to a standardised biopsy protocol and proper controls. But biopsies are not recommended in all routine classical cases of reflux disease since it is believed that little further information in addition to endoscopy can be obtained. However, histology can deliver much more information than the diagnosis of reflux induced lesions (e.g. the exclusion of malignancy or other oesophageal diseases).

Gastroesophageal reflux disease leads to major alterations in lectin-binding in the columnar epithelium of the gastroesophageal junction

OBJECTIVE

Chronic gastritis and esophagitis are associated with changes in glycosylation patterns. Lectins are carbohydrate-binding proteins that are used as sensitive tools in the analysis of glycosylation patterns. The aim was to investigate the binding patterns of lectins UEA-I, DBA, HPA and PNA at the squamocolumnar junction in relation to the existence of gastroesophageal reflux disease (GERD) and Helicobacter pylori (H. pylori) infection.

MATERIAL AND METHODS

Eighty-eight patients with either dyspeptic or gastroesophageal reflux-related symptoms were included in the study and stratified into four subgroups based on the presence of GERD and H. pylori infection. The binding patterns of lectins were examined immunohistochemically at the squamocolumnar junction, in squamous (SE) and columnar-lined epithelium (CLE). Staining patterns of lectins were semiquantitatively evaluated using an immunohistochemical score; data were analyzed using the non-parametric Mann-Whitney U-test.

RESULTS

The presence of GERD led to significant changes in lectin-binding patterns. Lectin-binding was significantly reduced for UEA-I (p<0.0001), DBA (p<0.0001), PNA (p<0.01) and DBA (p<0.05) in CLE and SE of patients with GERD, respectively. H. pylori infection was associated with reduced PNA and DBA binding to the deep glandular mucosa of CLE (p<0.05) and surface SE (p<0.05), respectively.

CONCLUSIONS

Distinct and complex changes in lectin-staining patterns are most prominent in CLE of patients with GERD. The functional relevance of changes in the glycosylation patterns needs further investigation.

Evaluation of pig esophageal mucosa as a permeability barrier model for buccal tissue

Porcine buccal mucosa is frequently used for in vitro drug absorption studies as its structure and permeability characteristics are close to those of human tissue. However, this tissue model suffers from practical disadvantages, including a limited surface area, damage caused by mastication, and a fastidious and time-consuming excision procedure. It has been hypothesized that such limitations may be overcome by replacing the buccal tissue with the pig esophageal mucosa. The latter has a very similar structure and is easier to separate from the underlying tissue; furthermore, its surface area is greater and is generally intact. The aims of this work, therefore, were (i) to perform histological studies on the two membranes; (ii) to compare the transport of fentanyl citrate across buccal and esophageal mucosae; and (iii) to evaluate the effects of freezing on the tissue permeability. The results show that their histology is comparable, that the permeability of fentanyl citrate across the two epithelial barriers is similar, and that freezing the tissues did not alter their permeability.

Analysis of the distribution of binding sites for the plant lectin Bandeiraea simplicifolia I-isolectin B4 on primary sensory neurones in seven mammalian species

The purpose of the present study was to investigate the binding patterns of the plant lectin Bandeiraea simplicifolia I-isolectin B(4) (BSI-B(4)) to sensory neurones in seven mammalian species. The dorsal root ganglia and spinal cords of three rats, mice, guinea pigs, rabbits, flying foxes, cats, and marmoset monkeys were screened for BSI-B(4) using lectin histochemistry. BSI-B(4) binding was associated with the soma of predominantly small-diameter primary sensory neurones in the dorsal root ganglia and their axon terminals within laminae I and II of the superficial dorsal horn in all seven species. The similarities of lectin binding patterns in each of these species suggest that the glycoconjugate to which BSI-B(4) binds has a ubiquitous distribution in mammals, and supports the proposal that this lectin may preferentially bind to a subpopulation of sensory neurones with a similar functional role in each of these species.

Distribution of binding sites for the plant lectin Ulex europaeus agglutinin I on primary sensory neurones in seven different mammalian species

There is an increasing body of evidence to suggest that different functional classes of neurones express characteristic cell-surface carbohydrates. Previous studies have shown that the plant lectin Ulex europaeus agglutinin-I (UEA) binds to a population of small to medium diameter primary sensory neurones in rabbits and humans. This suggests that a fucose-containing glycoconjugate may be expressed by nociceptive primary sensory neurones. In order to determine the extent to which this glycoconjugate is expressed by other species, in the current study, we have examined the distribution of UEA-binding sites on primary sensory neurones in seven different mammals. Binding sites for UEA were associated with the plasma membrane and cytoplasmic granules of small to medium dorsal root ganglion cells and their axon terminals in laminae I-III of the grey matter of the spinal cord, in the rabbit, cat and marmoset monkey. However, no binding was observed in either the dorsal root ganglia or spinal cord in the mouse, rat, guinea pig or flying fox. These results indicate an inter-species variation in the expression of cell-surface glycoconjugates on mammalian primary sensory neurones.