Human Esophageal Mucosa Research Articles

Proteinase-Activated Receptor-2 in the Pathogenesis of Gastroesophageal Reflux Disease

The proteinase-activated receptor-2 (PAR-2) is activated by serine proteases and has been demonstrated to induce proinflammatory and neuroinflammatory effects. It is considered to alter transepithelial resistance and mediates visceral hypersensitivity. This study aimed to evaluate the expression of PAR-2 in human esophageal mucosa of patients with gastroesophageal reflux disease (GERD) in relation to mucosal alterations. The study included 123 patients with GERD stratified to erosive reflux disease (n=50), non-erosive reflux disease (n=46), and reflux-negative patients as controls (n=27). Endoscopic and histopathological characterization was performed according to the Los Angeles classification and modified Ismail-Beigi criteria, respectively. PAR-2 expression was analyzed by quantitative reverse transcription (RT)-PCR and immunohistochemistry. The gene expression levels of interleukin (IL)-8 were determined by quantitative RT-PCR and correlated to PAR-2 expression in each patient. Performing in vitro studies, esophageal squamous cell lines (KYSE 150, KYSE 450) were incubated, adjusted to different pH (7.0, 6.0, and 5.0), and exposed to bile acids and PAR-2-activation peptide (SLIGKV-NH(2)). PAR-2 gene expression was 7- to 10-fold upregulated (P<0.0001) in the mucosa of patients with GERD and correlated positively with IL-8 expression and with histomorphological alterations (dilated intercellular spaces, papillary elongation, basal cell hyperplasia (BCH); P<0.01). Immunohistochemistry showed an intense staining of PAR-2 throughout all epithelial layers in patients with GERD compared with controls (P=0.0005). In vitro studies revealed a 1.5- to 20-fold induction of PAR-2 gene expression in esophageal squamous cells by acidified medium (P<0.01), but not by additional bile acids. The activation of PAR-2 leads to expression and secretion of IL-8. This study provides evidence of the functional importance of PAR-2-mediated pathways in the pathogenesis of GERD and GERD-associated mucosal alterations and inflammatory changes.

Acid and weakly acidic solutions impair mucosal integrity of distal exposed and proximal non-exposed human oesophagus

BackgroundOesophageal mucosa dilated intercellular spaces (DIS) may be important for symptom perception in non-erosive reflux disease (NERD). Patients with NERD might have DIS even in the proximal oesophagus. We aimed...

Angiotensin II receptors are expressed and functional in human esophageal mucosa

Only few studies have been devoted to the actions of the renin-angiotensin system (RAS) in the human gastrointestinal tract. The present study was undertaken to elucidate the expression and action of RAS in the human esophageal mucosa. Mucosal specimens with normal histological appearance were obtained from healthy subjects undergoing endoscopy and from patients undergoing esophagectomy due to neoplasm. Gene and protein expressions of angiotensin II (Ang II) receptor type 1 (AT(1)) and type 2 (AT(2)) and angiotensin-converting enzyme (ACE) were analyzed. In vivo functionality in healthy volunteers was reflected by assessing transmucosal potential difference (PD). Ussing chamber technique was used to analyze the different effects of Ang II on its AT(1) and AT(2) receptors. Immunoreactivity to AT(1) and AT(2) was localized to stratum superficiale and spinosum in the epithelium. ACE, AT(1), and AT(2) were found in blood vessel walls. Transmucosal PD in vivo increased following administration of the AT(1) receptor antagonist candesartan. In Ussing preparations mean basal transmural PD was -6.4 mV, epithelial current (I(ep)) 34 muA/cm(2), and epithelial resistance (R(ep)) 321 Omega.cm(2). Serosal exposure to Ang II increased PD as a result of increased I(ep), whereas R(ep) was constant. Ang II given together with the selective AT(1)-receptor antagonist losartan, or AT(2) agonist C21 given alone, resulted in a similar effect. Ang II given in presence of the AT(2)-receptor antagonist PD123319 did not influence PD, but I(ep) decreased and R(ep) increased. In conclusion, Ang II receptors and ACE are expressed in the human esophageal epithelium. The results suggest that AT(2)-receptor stimulation increases epithelial ion transport, whereas the AT(1) receptor inhibits ion transport and increases R(ep).

Alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase activity in the sera of patients with esophageal cancer

Various alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) exist in the human esophageal mucosa. In our last experiments we have shown that ADH and ALDH are present also in the esophageal cancer cells. Moreover, the activities of total ADH and class IV isoenzymes were significantly higher in cancer tissue than in healthy mucosa, which suggests that these changes may be reflected by enzyme activity in the serum. Therefore, we measured the activity of total alcohol dehydrogenase, and classes I-IV of this enzyme and aldehyde dehydrogenase in the sera of patients with this cancer. Serum samples were taken for routine biochemical investigation from 67 patients with esophageal cancer before treatment. Total ADH activity was measured by photometric method with p-nitrosodimethylaniline (NDMA) as a substrate and ALDH activity by the fluorometric method with 6-methoxy-2-naphtaldehyde as a substrate. For the measurement of the activity of class I and II isoenzymes, we employed the fluorometric methods, with class-specific fluorogenic substrates. The activity of class III alcohol dehydrogenase was measured by the photometric method with formaldehyde and class IV with m-nitrobenzaldehyde as a substrate. A statistically significant increase of class IV alcohol dehydrogenase isoenzymes was found in the sera of cancer patients. The median activity of this class isoenzyme in the total cancer group increased by about 26.5% (7.42 mU/l) in comparison to the control level (5.46 mU/l). The total alcohol dehydrogenase activity was significantly higher (30%) among patients with cancer. The activities of other tested ADH isoenzymes and total ALDH were unchanged. The activity of the class I ADH isoenzyme was significantly higher in the sera of drinkers with esophageal cancer than non-drinking patients. The increased total activity of alcohol dehydrogenase and class IV isoenzyme in the sera of patients with esophageal cancer probably can be caused by release of this isoenzyme from cancer cells or might be stimulated by alcohol drinking.

Expression of protease-activated-receptor 2 (PAR-2) in human esophageal mucosa

Objective. The role of duodenal reflux in gastroesophageal reflux disease (GERD) containing bile salts and pancreatic enzymes (with special attention to trypsin) is still under discussion. Proteinase-activated receptors (PARs) are a novel family and PAR-2 is a unique member of this family because it is activated by trypsin. The aim of the present study was to examine the presence and the position of the PAR-2 receptor in human esophageal mucosa in different subgroups of GERD. Material and methods. Distal biopsies taken from healthy controls, patients with erosive reflux disease (ERD), patients with specialized intestinal metaplasia (SIM) and adenocarcinoma were analyzed for the PAR-2 receptor with reverse-transcription polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry. Results. Gene transcripts for the PAR-2 receptor were found in all groups, with increased levels in SIM patients compared to controls. However, this visual pattern was not seen for the protein expression of the PAR-2 receptor showing no apparent quantitative differences between the groups. Immunohistochemistry revealed distinct staining for the PAR-2 receptor in the luminal part of the esophageal epithelium. Conclusions. The localization of the PAR-2 receptor indicates that the receptor can be cleaved and activated by trypsin in duodenogastric esophageal refluxate. The data thus suggest that the trypsin-PAR-2 pathway may be involved in the pathogenesis of GERD.

Natriuretic peptides cause relaxation of human esophageal mucosal muscle

Natriuretic peptides have been demonstrated to cause relaxation of the human gallbladder muscle through interaction with natriuretic peptide receptor-B (NPR-B/NPR2). Effects of natriuretic peptides in the human esophageal muscle were unknown. To investigate the effects of natriuretic peptides in the human esophagus, we measured relaxation of muscularis mucosae strips isolated from the human esophagus caused by C-type natriuretic peptide (CNP), brain natriuretic peptide (BNP), atrial natriuretic peptide (ANP) and des[Gln 18, Ser 19, Gly 20, Leu 21, Gly 22]ANP(4-23) amide (cANP(4-23)), a selective natriuretic peptide receptor-C (NPR-C) agonist. In endothelin-1 or carbachol-contracted mucosal muscle strips, CNP caused moderate, sustained and concentration-dependent relaxation. BNP caused a very mild relaxation whereas ANP and cANP(4-23) did not cause any relaxation. CNP was much more potent than BNP and ANP in causing relaxation. These suggest the existence of NPR-B mediating relaxation. The CNP-induced relaxation was not affected by tetrodotoxin or atropine in endothelin-1-contracted esophageal strips and not by tetrodotoxin in carbachol-contracted strips, indicating a direct effect of CNP on the human esophageal muscularis mucosae. Taken together, these results demonstrate that natriuretic peptides cause relaxation of the muscularis mucosae of the human esophagus and suggest that the relaxation is through interaction with NPR-B. Natriuretic peptides may play an important role in the control of human esophageal motility.

Bile acids induce overexpression of homeobox gene CDX-2 and vascular endothelial growth factor (VEGF) in human Barrett's esophageal mucosa and adenocarcinoma cell line

Objective. Barrett's esophagus (BE) is an acquired precancerous condition that develops from mucosal injury incurred after chronic gastroesophageal acid and bile reflux. The mechanism of progression of carcinogenesis in BE is still not fully understood. Recently, the role of bile acids and the homeobox gene transcription factor CDX-2 has been suggested in the pathogenesis of BE. The aims of the present study were 1) to compare the mRNA and protein expression of CDX-2 in biopsies obtained from patients with BE and normal squamous epithelium and 2) to study the effect of two different bile salts, ursodeoxycholic acid (UDCA) and deoxycholic acid (DCA), on the mRNA expression of CDX-2 and vascular endothelial growth factor (VEGF) in Barrett's the adenocarcinoma cell line (OE-33). Material and methods. CDX-2 expression was measured in Barrett's mucosa and normal esophageal mucosa obtained from 15 patients with BE histologically diagnosed by immunohistochemistry, Western blot, and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). In in vitro experiments, OE-33 cells were incubated with DCA (100 µM) and UDCA (100 µM) in neutral and shortly acidified media (pulse acidification). The expression of CDX-2 and VEGF was assessed by quantitative RT-PCR. Results. Both mRNA and protein expression of CDX-2 were significantly up-regulated in Barrett's mucosa as compared to normal esophageal mucosa. In neutral medium, OE-33 cells showed an increase in CDX-2 expression after incubation with DCA or UDCA. After short acidification of the medium, expression of CDX-2 in OE-33 cells was significantly higher than that in cells incubated in neutral pH. The addition of DCA and UDCA did not cause any further alteration in CDX-2 expression. In neutral and acidified medium, VEGF mRNA expression was only significantly up-regulated by DCA, but not by UDCA. Conclusions. Bile acids, especially in acidic medium, increase expression of CDX-2. DCA appears to be a stronger stimulant of the expression of VEGF than UDCA in the Barrett's carcinoma cell line, indicating a stronger carcinogenic potential of this bile salt.

Gastroesophageal Reflux Disease–Associated Esophagitis Induces Endogenous Cytokine Production Leading to Motor Abnormalities

Gastroesophageal reflux disease is a condition frequently associated with esophagitis and motor abnormalities. Recent evidence suggests that proinflammatory cytokines, such as interleukin (IL)-1beta and IL-6, may be implicated because they reduce esophageal muscle contractility, but these results derive from in vitro or animal models of esophagitis. This study used human esophageal cells and tissues to identify the cellular source of cytokines in human esophagitis investigate whether cytokines can be induced by gastric refluxate, and examine whether esophageal tissue- or cell-derived mediators affect muscle contractility. Endoscopic mucosal biopsy specimens were obtained from patients with and without esophagitis, organ-cultured, and undernatants were assessed for cytokine content. The cytokine profile of esophageal epithelial, fibroblast, and muscle cells was analyzed, and esophageal mucosa and cell products were tested in an esophageal circular muscle contraction assay. The mucosa of esophagitis patients produced significantly greater amounts of IL-1beta and IL-6 compared with those of control patients. Cultured esophageal epithelial cells produced IL-6, as did fibroblasts and muscle cells. Epithelial cells exposed to buffered, but not denatured, gastric juice produced IL-6. Undernatants of mucosal biopsy cultures from esophagitis patients reduced esophageal muscle contraction, as did supernatants from esophageal epithelial cell cultures. The human esophagus produces cytokines capable of reducing contractility of esophageal muscle cells. Exposure to gastric juice is sufficient to stimulate esophageal epithelial cells to produce IL-6, a cytokine able to alter esophageal contractility. These results indicate that classic cytokines are important mediators of the motor disturbances associated with human esophageal inflammation.

Bile salts induce differentiation in cultured human normal esophageal mucosal epithelial cells

To investigate the effects of bile salts on the proliferation and differentiation of human normal esophageal mucosal epithelial cells on cultured. Normal human esophageal mucosa was obtained during operation. The esophageal epithelial cells were isolated, cultured, and treated with 6 different conjugated bile salts [glycocholate (GC), glycochenodeoxycholate (GCDC), glycodeoxycholate (GDC), taurochenodeoxycholate (TCDC), and taurodeoxycholate (TDC), all of the concentration of 50 micromol/L, and taurocholate (TC) of the concentration of 20 micromol/L], and their mixtures the concentration of 50 micromol/L respectively. One, three, and five days later MTT assay was applied to detect the cell proliferation. The cell cycle was assayed by flow cytometry with propidium iodide staining 1 and 3 d after treating with the bile salts. The cytokeratin 13 (CK13) in the differentiated cells and cytokeratin 14 (CK14) in the proliferating cells were detected by immunocytochemical assay. The concentration of intercellular calcium ([Ca(2+)]i) was analyzed by Laser Scanning Confocal Microscope (LSCM) in cells with TC, mixed bile salts and GC. The cultured esophageal epithelial cells treated by the bile salts, except those treated by GC for 1 - 3 days, became larger and shuttle-like, with the cell proliferation inhibited, the percentages of cells in G(0)-G(1) phase increased and percentages of cells in S phase decreased. The percentages of CK14 positive cells were increased, but the percentages of CK13 positive cells were decreased time-dependently in cells treated for 1 - 5 days. The most obvious effects were seen in those cells treated with TC. The percentage of CK13 positive cells reached 74% +/- 8% in those cells treated with TC for 5 days, higher significantly than the percentage in the control cell (22% +/- 7%), (P < 0.01). The [Ca(2+)]i increased significantly only several minutes after treatment of TC and mixed bile salts, however, GC failed to cause the increase of [Ca(2+)]i. GCDC, GDC, TC, TCDC, TDC and their mixture all induce differentiation of cultured human normal esophageal mucosal epithelial cells, but nor does GC. Increased [Ca(2+)]i is related to the TC-induced differentiation in those esophageal mucosal epithelial cells.

Acid-Induced Release of Platelet-Activating Factor by Human Esophageal Mucosa Induces Inflammatory Mediators in Circular Smooth Muscle

In a human in vitro model of esophagitis, we investigated the genesis of esophagitis-associated dysmotility by examining HCl-induced production of inflammatory mediators in the mucosa and investigating their effect on esophageal circular muscle. Muscularis propria was removed from organ donors' esophagi, leaving the mucosal tube intact. The tube was tied at both ends, forming a sac, and filled with HCl at pH 4. After 3 h of incubation, the supernatant surrounding the sac was analyzed or applied to circular muscle strips. HCl alone did not affect circular muscle contraction in response to electrical field stimulation (EFS), but supernatant of HCl-treated mucosa abolished contraction. The inhibition was reversed by the platelet-activating factor (PAF) antagonist CV3988 [(+/-)-3-(N-octadecylcarbamoyl)-2-methoxy) propyl-(2-thiazolioethyl) phosphate], whereas the PAF analog 2-O-methyl platelet-activating factor C-16 (PAF-16) inhibited EFS-induced contraction and acetylcholine (ACh) release in circular muscle strips. The hydrogen peroxide scavenger catalase reversed the inhibition in contraction, to the same extent as CV3988. We therefore measured PAF and hydrogen peroxide (H(2)O(2)) in mucosa, mucosa supernatant, and circular muscle. HCl increased PAF and interleukin (IL)-1beta (but not IL-6, prostaglandin E(2), or H(2)O(2)) in mucosa, and only PAF was released into the supernatant, presumably to affect circular muscle. In circular muscle, exogenous PAF induced sequential formation of IL-6, H(2)O(2), IL-1beta, and PAF. Release of PAF by the mucosa inhibits ACh release from circular muscle layer neurons and initiates sequential formation of inflammatory mediators in muscle, resulting in production of PAF by the muscle itself, possibly initiating in a self-sustaining cycle.

Expression of RUNX3 Protein in Human Esophageal Mucosa and Squamous Cell Carcinoma

Runt-related transcriptional factor gene 3 (RUNX3) belongs to the runt domain family of transcriptional factors that plays an important role during normal tissue development and in tumorigenesis in several organs. This study examined the expression of RUNX3 protein in human esophageal mucosa and squamous cell carcinoma in comparison with clinicopathological profiles. Western blot analysis and RT-PCR revealed that both RUNX3/P44 and P27, but not P46, were expressed in all three human esophageal squamous cell carcinoma (SCC) cell lines, as well as in three pairs of esophageal SCC cell lines and the corresponding nontumoral mucosa specimens. RUNX3 expression was shown in prickle and functional cell layer cells in normal esophageal mucosa. On the other hand, immunoreactivity was seen only in carcinoma cells around the cancer pearls. RUNX3 expression was significantly higher in the 19 well-differentiated SCCs than in the 56 moderately or 69 poorly differentiated SCCs (p < 0.01). The 3-year survival rate was significantly lower in the 29 patients with lower RUNX3 expression than in the 37 patients with higher expression (p = 0.0003). These results indicated that RUNX3 protein might play an important role in cellular differentiation in both esophageal mucosa and SCC. The expression correlated with the patients’ prolonged survival, implying a tumor suppressive effect in esophageal SCCs.

Acid Challenge to the Human Esophageal Mucosa: Effects on Epithelial Architecture in Health and Disease

The histological changes that occur in the squamous epithelium in response to acute acid challenge was examined in healthy controls and proton pump inhibitor-treated gastroesophageal reflux disease (GERD) patients and related to the state of untreated erosive GERD in a saline-controlled, randomized perfusion study. In the basal state a stepwise significant increase in the thickness of the basal cell layer, papillary length, and dilatation of intercellular spaces (DIS) was seen when the three groups were compared. Acid perfusion induced a slight increase in the height of the basal cell layer mainly in healthy volunteers; this layer appears to be reactive to acute acid challenge as well as to acid suppressive therapy. DIS increases promptly in response to acute acid exposure in the healthy epithelium but no changes were seen in the lengths of the papillae or regarding DIS in the GERD patients. A protective effect of luminal nitric oxide on DIS development is suggested.

Expression of L-type amino acid transporter 1 (LAT1) in esophageal carcinoma

It has been reported that amino acid transport systems play an important role in cell proliferation. Their activity is increased in malignant cells compared to benign cells. In this study, we investigated whether L-type amino acid transporter 1 (LAT1) is expressed in human non-cancerous esophageal mucosa and esophageal squamous cell carcinoma. We also examined whether LAT1 expression is correlated with histopathological features. From January 1999 to December 2001, sections of formalin-fixed, paraffin-embedded tissue from 11 cases of early esophageal carcinoma (T1) and 19 cases of advanced esophageal carcinoma (T2, T3) were entered in the study. Histopathologically, all 30 cases were squamous cell carcinoma. Immunohistochemical staining was performed using rabbit anti-LAT1 IgG, with the standard avidin-streptavidin immuno-peroxidase method. Measurement was performed by means of computer-assisted image analysis. The ratio of cells with LAT1 expression in esophageal squamous cell carcinoma and non-cancerous esophageal mucosa was used for analysis in this study. Non-cancerous esophageal mucosa expressed LAT1 only in the basal layer of the esophageal wall. Esophageal squamous cell carcinoma expressed LAT1 throughout the tumor. LAT1 expression in esophageal squamous cell carcinoma was significantly higher than that in non-cancerous esophageal mucosa. LAT1 expression in esophageal squamous cell carcinoma increased as the depth of invasion progressed (T1 < T2 (P = 0.0477), T2 < T3 (P = 0.0415), T1 < T3 (P = 0.0044)), and as the tumor size increased. Also, high LAT1 expression was significantly associated with well-differentiated carcinoma. These results suggest that LAT1 plays a significant role in cell proliferation, differentiation, and invasion in esophageal squamous cell carcinoma.

Increased capsaicin receptor TRPV1 nerve fibres in the inflamed human oesophagus.

Gastro-oesophageal reflux disease (GORD) patients commonly describe symptoms of heartburn and chest pain. The capsaicin receptor vanilloid receptor 1 (TRPV1) (VR1) is a cation channel expressed by sensory neurones and activated by heat, acid pH and ethanol, which may trigger burning pain. To study the distribution of TRPV1-expressing nerve fibres in oesophageal mucosal biopsies from patients with symptomatic oesophagitis and in control subjects. Biopsies were taken at gastroscopy from the distal oesophagus of seven symptomatic oesophagitis patients and seven asymptomatic patients undergoing investigation for iron-deficiency anaemia. These biopsies were studied by immunohistochemistry using affinity-purified antibodies to TRPV1 and to the neuronal marker peripherin. The density of oesophageal epithelial TRPV1 innervation was assessed by calculating the proportion of papillae in each oesophageal epithelium biopsy specimen containing TRPV1-immunoreactive fibres. TRPV1-immunoreactive nerves were distributed within the lamina propria in healthy subjects and in oesophagitis patients. The percentage of papillae positive for TRPV1 was elevated in oesophagitis patients compared with controls. Peripherin fibre density was not significantly different between the groups. TRPV1-immunoreactive sensory nerve fibres are expressed in human oesophageal mucosa both in health and in disease. Increased TRPV1 expression in the inflamed oesophagus may mediate the heartburn in oesophagitis, and TRPV1 blockers may provide novel treatment.

Expression of Cyclooxygenase-1 and Cyclooxygenase-2 in Human Esophageal Mucosa, Dysplasia and Carcinoma

Objective: COX (cyclooxygenase), a prostaglandin H synthase, catalyzes the rate-limiting step in prostaglandin biosynthesis. Two isoforms of COX have been identified: COX-1 and COX-2. We examined the expression of COX-1 and COX-2 in esophageal normal mucosa, dysplasia and squamous cell carcinoma (SCC). Methods: The expression of COX-1 and COX-2 in 80 surgically removed esophagi due to SCC, as well as in 5 human esophageal SCC cell lines was analyzed, using immunohistochemistry and Western blot analyses. Results: COX-1 and COX-2 were variably expressed in the SCC cell lines. Higher COX-1 expression was noted in 31 (41.9%) of the 74 specimens of normal mucosa, in none of the 40 specimens of dysplastic mucosa and in 15 (18.8%) of the 80 specimens of SCC, the frequency being significantly higher in normal mucosa than in dysplasia or SCC (p < 0.0001, p = 0.0018, respectively). COX-1 expression was significantly higher in well-differentiated SCC than in moderately or poorly differentiated SCC (p < 0.01). Higher COX-2 expression was noted in none (0.0%) of the specimens of normal mucosa, in 12 (30%) of the specimens of dysplastic mucosa, and in 41 (51.3%) of the speciments of SCC, the frequency being significantly higher in SCC than in normal mucosa or dysplasia (p < 0.0001, p = 0.0278, respectively). Conclusions: COX-1 is expressed in normal esophageal mucosa and is occasionally induced in well-differentiated SCC, whereas COX-2 expression is more characteristic of dysplasia and carcinoma than of normal mucosa, implying a possible association with cell differentiation in the former, and esophageal tumorigenesis in the latter.

Endothelin causes contraction of human esophageal muscularis mucosae through interaction with both ET A and ET B receptors

Endothelin (ET) causes contraction of the muscularis mucosae in the guinea pig esophagus, but its role in the human esophagus remains unknown. To investigate effects of ET in the human esophagus, we measured contraction of isolated human esophageal muscularis mucosae strips caused by ET related peptides and binding of 125I-ET-1 to cell membranes prepared from the human esophageal muscularis mucosae. Autoradiography demonstrated specific binding of 125I-ET-1 to the muscularis mucosae and muscularis propria (muscularis externa) of the human esophagus. ET-1 caused tetrodotoxin and atropine-insensitive contraction of muscularis mucosae strips. In terms of the maximal tension of contraction, ET-1 and ET-2 were equal in efficacy. The relative potencies for ET related peptides to cause contraction were ET-1=ET-2>ET-3>sarafotoxin S6c (SX6c), an ET B receptor agonist. ET-1 caused contraction was mildly inhibited by BQ-123, an ET A receptor antagonist, and not by BQ-788, an ET B receptor antagonist. It was moderately inhibited by the combination of both antagonists, indicating synergistic inhibition. Furthermore, desensitization to SX6c with SX6c pretreatment failed to abolish the contractile response to ET-1, which was completely inhibited by BQ-123. These indicate the involvement of both ET A and ET B receptors in the contraction. Binding of 125I-ET-1 to cell membranes of the muscularis mucosae was saturable and specific. Analysis of dose–inhibition curves demonstrated the presence of ET A and ET B receptors. This study demonstrates that, the muscularis mucosae of the human esophagus, similar to that of the guinea pig esophagus, possesses both ET A and ET B receptors mediating muscle contraction.

Endothelin causes contraction of human esophageal muscularis mucosae through interaction with both ETA and ETB receptors

Endothelin (ET) causes contraction of the muscularis mucosae in the guinea pig esophagus, but its role in the human esophagus remains unknown. To investigate effects of ET in the human esophagus, we measured contraction of isolated human esophageal muscularis mucosae strips caused by ET related peptides and binding of 125I-ET-1 to cell membranes prepared from the human esophageal muscularis mucosae. Autoradiography demonstrated specific binding of 125I-ET-1 to the muscularis mucosae and muscularis propria (muscularis externa) of the human esophagus. ET-1 caused tetrodotoxin and atropine-insensitive contraction of muscularis mucosae strips. In terms of the maximal tension of contraction, ET-1 and ET-2 were equal in efficacy. The relative potencies for ET related peptides to cause contraction were ET-1=ET-2>ET-3>sarafotoxin S6c (SX6c), an ETB receptor agonist. ET-1 caused contraction was mildly inhibited by BQ-123, an ETA receptor antagonist, and not by BQ-788, an ETB receptor antagonist. It was moderately inhibited by the combination of both antagonists, indicating synergistic inhibition. Furthermore, desensitization to SX6c with SX6c pretreatment failed to abolish the contractile response to ET-1, which was completely inhibited by BQ-123. These indicate the involvement of both ETA and ETB receptors in the contraction. Binding of 125I-ET-1 to cell membranes of the muscularis mucosae was saturable and specific. Analysis of dose-inhibition curves demonstrated the presence of ETA and ETB receptors. This study demonstrates that, the muscularis mucosae of the human esophagus, similar to that of the guinea pig esophagus, possesses both ETA and ETB receptors mediating muscle contraction.

Variation in Langerhans cell number and morphology between the upper and lower regions of the human esophageal epithelium.

Langerhans cells (LCs) are dendritic components of stratified epithelia, presenting antigens to other cells of the immune system that play a crucial role in local defense. The paucity of information about their significance in the esophageal mucosa was addressed by studying their distribution and morphology in this particular location. LCs were identified by immunohistochemical detection of CD1a, a cell-specific marker, using a monoclonal antibody, as well as by electron microscopic identification of characteristic Birbeck granules, among other typical morphological features. Cell counts carried out at 25 and 35 cm distal to the dental arch demonstrated significant differences in number and size between the two locations. The upper region contained 10.4 +/- 0.8 cells (mean +/- SEM) vs. 18.4 +/- 1.4 cells in the lower region. Also, cells in the lower region were larger and appeared to have longer dendritic processes. To our knowledge this is the first report of regional differences in number and morphology of LCs in human esophageal mucosa.

CYP2A6/2A7 and CYP2E1 expression in human oesophageal mucosa: regional and inter-individual variation in expression and relevance to nitrosamine metabolism.

Oesophageal cancer is one of the most common and lethal malignancies in the world. Despite many efforts, treatment is still ineffective for most cases; thus, the development of preventive strategies is crucial for decreasing the burden presented by this disease. Environmental factors, particularly nitrosamines, are thought to be involved in the genesis of oesophageal tumours, and knowledge about the expression of enzymes capable of activating pre-carcinogens in human oesophagus is very important for the development of preventive measures. We analysed the expression of CYP1A1, CYP1A2, CYP2A6/2A7, CYP2E1 and CYP3A4 mRNA in oesophageal mucosa of 50 patients by semi-quantitative RT-PCR. In five patients, who suffered from squamous cell carcinoma, we measured Nnitrosodimethylamine and N-nitrosodiethylamine metabolism in normal and tumorous tissue. CYP2A6/2A7 mRNA was expressed in 61% and CYP2E1 mRNA in 96% of the patients, but in the latter a lower degree of inter-individual variation was observed. These enzymes were expressed either in the distal or middle portions of the oesophagus of 90% of the patients. CYP1A1, CYP1A2 and CYP3A4 mRNA expression was not detected in any portion of the oesophagus. Oesophageal microsomes activated N-nitrosodimethylamine with a low degree of inter-individual variation and microsomes prepared from the tumour of a patient who strongly expressed CYP2A6/2A7 mRNA activated N-nitrosodiethylamine. We conclude that the human oesophagus expresses CYP2A6/2A7 and CYP2E1 and can activate nitrosamines. Notably, the expression of these enzymes is preferentially localized to the most common sites where tumours arise.

Spatial distribution and cell kinetics of the glands in the human esophageal mucosa.

The glands in the human esophageal mucosa have been considered rudimentary, and have been poorly studied. Only recently, their role in the defense of the esophageal mucosa in gastroesophageal reflux disease has been put in evidence. In the present study, the presence of the different esophageal gland types was observed in 82 necropsy specimens. A precise topographical study was possible in 15 specimens. Cell proliferation parameters, namely DNA synthesis and mitotic index values in the squamous epithelium and in the esophageal glands were measured in 8 patients undergoing a surgical palliative esophagectomy, after in vivo labelling with bromodeoxyuridine. Upper mucosal, lower mucosal, and submucosal glands were observed in respectively 3.7%, 87% and 99% of the 82 esophageal specimens. Our topographical analysis showed that the upper mucosal glands, lower mucosal glands, and submucosal glands are occupying respectively 0.02%, 2.61%, and 3.96% of the esophageal surface. DNA synthesis and mitotic index values in the progenitor zone of the squamous epithelium were respectively 7.91% and 0.81%, whereas the proliferative activity in the glands was extremely low. The labelling index In the excretory ducts of the glands was only 0.07%, while no labelled cells nor mitotic figures were observed in any of the glandular acini.