Production of prostaglandinE2 via bile acid is enhanced by trypsin and acid in normal human esophageal epithelial cells

Does Trypsin Oral Spray (Viruprotect®/ColdZyme®) Protect against COVID-19 and Common Colds or Induce Mutation? Caveats in Medical Device Regulations in the European Union

BACKGROUND

nasal or oral sprays are often marketed as medical devices (MDs) in the European Union to prevent common cold (CC), with ColdZyme^®/Viruprotect^® (trypsin/glycerol) mouth spray claiming to prevent colds and the COVID-19 virus from infecting host cells and to shorten/reduce CC symptoms as an example. We analyzed the published (pre)-clinical evidence.

METHODS

preclinical: comparison of in vitro tests with validated host cell models to determine viral infectivity. Clinical: efficacy, proportion of users protected against virus (compared with non-users) and safety associated with trypsin/glycerol.

RESULTS

preclinical data showed that exogenous trypsin enhances SARS-CoV-2 infectivity and syncytia formation in host models, while culture passages in trypsin presence induce spike protein mutants. The manufacturer claims >98% SARS-CoV-2 deactivation, although clinically irrelevant as based on a tryptic viral digest, inserting trypsin inactivation before host cells exposure. Efficacy and safety were not adequately addressed in clinical studies or leaflets (no COVID-19 data). Protection was obtained among 9-39% of users, comparable to or lower than placebo-treated or non-users. Several potential safety risks (tissue digestion, bronchoconstriction) were identified.

CONCLUSIONS

the current European MD regulations may result in insufficient exploration of (pre)clinical proof of action. Exogenous trypsin exposure even raises concerns (higher SARS-CoV-2 infectivity, mutations), whereas its clinical protective performance against respiratory viruses as published remains poor and substandard.

Effect of nonsteroidal anti-inflammatory drugs on Barrett's esophagus risk: a systematic review and meta-analysis

OBJECTIVE

Conflicting evidence exists regarding the effect of NSAIDs on the risk of Barrett's esophagus. The purpose of this study is to systematically assess this effect through a meta-analysis.

METHODS

Accordingly, clinical studies on NSAID use and Barrett's esophagus risk were searched on PubMed, Embase, and the Cochrane Library. Following this, meta-analyses were conducted using the RevMan 5.3 software. The pooled odds ratio (OR) and corresponding 95% confidence interval (CI) were used as the effect size.

RESULTS

Seven eligible studies (one cohort study and six case-control studies) were included for the present meta-analysis by adopting a fixed-effect model, which demonstrated that NSAIDs could reduce Barrett's esophagus risk (OR: 0.84, 95%CI:0.75-0.94, P＜0.05). Moreover, subgroup analyses done according to sex showed that NSAIDs could reduce Barrett's esophagus risk in females (OR 0.85; 95% CI 0.73-0.99; P = 0.04), without heterogeneity between studies (P = 1.00 and I² = 0%). However, this relationship was not evident in males (OR 0.85; 95% CI 0.68-1.07; P = 0.16).

CONCLUSIONS

Overall, this meta-analysis provided high quality evidence that use of NSAIDs is associated with a reduced risk of Barrett's esophagus. However, the presence of a sex-dependent difference remains to be clarified.

Duodenal Contents Reflux-Induced Laryngitis in Rats: Possible Mechanism of Enhancement of the Causative Factors in Laryngeal Carcinogenesis

Objectives:

The main factors considered responsible for the onset of laryngeal cancer are tobacco smoking and alcohol abuse. Recently, gastroesophageal reflux has also been implicated as a causative factor in several laryngeal disorders, including laryngeal cancer. However, the significance of gastroesophageal reflux in laryngeal cancer is controversial.

Methods:

We investigated the histologic features of the esophagus and larynx in a rat model of reflux of the duodenal contents. Cell proliferation was also evaluated in laryngeal samples by detection of Ki67 antigen.

Results:

In this reflux model, laryngitis with infiltration of inflammatory cells and proliferation of small mucous glands was evident from 10 weeks after operation, and basal cell hyperplasia around the epiglottis and hyperplastic changes in the larynx were detected at 30 weeks. No dysplastic or malignant lesions were detected in the laryngeal samples within the duration of the experiment, in spite of detection of malignancy in 31.3% of lesions in esophageal samples at 30 weeks. The Ki67 index at each week was significantly higher than that of the control animals.

Conclusions:

Previous studies have shown smoking and alcohol abuse to have refluxogenic effects. Reflux of duodenal contents causes laryngitis. Reflux does not appear to be an independent risk factor for laryngeal carcinogenesis, but it may enhance the acknowledged etiologic risk factors, namely, smoking and alcohol abuse, by promoting cell proliferation.

Ion/Water Channels for Embryo Implantation Barrier

Successful implantation involves three distinct processes, namely the embryo apposition, attachment, and penetration through the luminal epithelium of the endometrium to establish a vascular link to the mother. After penetration, stromal cells underlying the epithelium differentiate and surround the embryo to form the embryo implantation barrier, which blocks the passage of harmful substances to the embryo. Many ion/water channel proteins were found to be involved in the process of embryo implantation. First, ion/water channel proteins play their classical role in establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane. Second, most of ion/water channel proteins are regulated by steroid hormone (estrogen or progesterone), which may have important implications to the embryo implantation. Last but not least, these proteins do not limit themselves as pure channels but also function as an initiator of a series of consequences once activated by their ligand/stimulator. Herein, we discuss these new insights in recent years about the contribution of ion/water channels to the embryo implantation barrier construction during early pregnancy.

Adenocarcinoma in long-segment Barrett's esophagus 44 years after total gastrectomy

Although Barrett's esophagus may occur without gastric acid, Barrett's adenocarcinoma after total gastrectomy is rare. Here, we present Barrett's adenocarcinoma in long-segment Barrett's esophagus after total gastrectomy. The patient was a 74-year-old male who underwent total gastrectomy 44 years ago. An endoscopic examination revealed long-segment Barrett's esophagus starting 17 cm from the incisors and continuing 20 cm to esophagojejunostomy, with irregular mucosa 27-31 cm from the incisors. Pathological diagnosis of a biopsied specimen was adenocarcinoma. We performed subtotal esophagectomy with lymph node dissection in the prone position and reconstructed the esophagus with ileocolic interposition. Postoperative pathological diagnosis from a Barrett's epithelial section was well differentiated adenocarcinoma. This case had the longest interval from total gastrectomy and smallest oral margin of Barrett's epithelium. Our case suggested that careful surveillance is needed for patients exhibiting recurrent bile reflux following total gastrectomy.

Analysing the role of COX-2 in acute oesophagitis and in melatonin-exerted protection against experimental reflux oesophagitis in rats†

Objectives

Cyclooxygenase(COX)-2 is implicated in variety of pathophysiological processes, although its role in acute reflux oesophagitis is debatable. This study was designed to evaluate the role of COX-2 during oesophagitis and in melatonin-elicited protection in rats.

Methods

Reflux oesophagitis was induced in rats by ligating the pyloric end and the limiting ridge of the stomach for 5 h. Celecoxib (COX-2 blocker; 10 mg/kg), 16,16-dimethyl prostaglandinE2 (dmPGE2; a synthetic analogue of PGE2; 10 µg/kg), melatonin (20 and 40 mg/kg) and omeprazole (10 mg/kg) were given intra-peritoneally 45 min before induction of oesophagitis in rats. Alterations in COX-1 and 2 gene expression and protein levels level were analysed via RT-PCR and Western blotting, respectively. Mucosal PGE2 level and myeloperoxidase (MPO) activity were measured using an enzyme immunoassay (EIA) kit and spectrophotometrically, respectively.

Key findings

COX-2 over-expression during reflux oesophagitis promotes inflammation of the oesophagus as celecoxib pretreatment significantly reduced tissue damage and MPO activity in rats with reflux oesophagitis (RE-rats). By contrast, dmPGE2 pretreatment significantly exacerbated tissue injury and simultaneously increased COX-2 expression, PGE2 levels and MPO activity in RE-rats. Further, melatonin pretreatment significantly reduced the tissue injury, COX-2 over-expression, PGE2 level and MPO activity in RE-rats. Melatonin offered more potent suppression of COX-2, PGE2 and MPO activity than the proton-pump inhibitor omeprazole; however, both reduced the lesion injury to a similar extent. Melatonin at a dose of 20 mg/kg failed to inhibit significantly the dmPGE2-induced tissue damage, COX-2 expression, PGE2 level and MPO activity in RE-rats while at a higher dose of 40 mg/kg it significantly attenuated these changes.

Conclusion

Our results suggest that COX-2 plays an important pro-inflammatory role during acute reflux oesophagitis in rats and its inhibition contributes significantly to melatonin-exerted protection against reflux oesophagitis.

Systematic review: the role of bile acids in the pathogenesis of gastro-oesophageal reflux disease and related neoplasia

BACKGROUND

Factors other than acid may play a role in gastro-oesophageal reflux disease (GERD) and its complications.

AIM

To assessed the role of bile acids in the pathogenesis of GERD, Barrett's oesophagus and Barrett's-related neoplasia.

METHODS

We conducted a systematic review of computerised bibliographic databases for original articles involving humans or human oesophageal tissue or cells that assessed exposure to or manipulation of bile acids. Outcomes assessed included GERD symptoms; gross oesophageal injury; Barrett's oesophagus and related neoplasia; and intermediate markers of inflammation, proliferation or neoplasia.

RESULTS

Eighty-three original articles were included. In in vivo studies, bile acids concentrations were higher in the oesophageal aspirates of patients with GERD than controls, and bile acids infusions triggered GERD symptoms, especially in high concentrations or in combination with acid. In ex vivo/in vitro studies, bile acids stimulated squamous oesophageal cells and Barrett's epithelial cells to produce inflammatory mediators (e.g., IL-8 and COX-2) and caused oxidative stress, DNA damage and apoptosis. They also induced squamous cells to change their gene expression pattern to resemble intestinal-type cells and caused Barrett's cells to increase expression of intestinal-type genes.

CONCLUSIONS

In aggregate, these studies suggest that bile acids may contribute to the pathogenesis of symptoms, oesophagitis and Barrett's metaplasia with related carcinogenesis in patients with GERD. However, all study results are not uniform and substantial differences in study parameters may explain at least some of this variation.

Induction of prostaglandin E synthase by gastroesophageal reflux contents in normal esophageal epithelial cells and esophageal cancer cells

The synthesis of prostaglandin E2 (PGE2) requires cyclooxygenase (COX) and prostaglandin E synthase (PGES). There are two forms of PGES: cytosolic PGES (cPGES) and microsomal PGES (mPGES)-1. In this study, we investigated the effects of gastroesophageal reflux (GER) contents on PGES and COX-2 in esophageal cells. We incubated a human normal esophageal cell line, two esophageal squamous cell carcinoma (SCC) cell lines, and two esophageal adenocarcinoma (ADC) cell lines with GER contents. The production of PGE2 by these cells was assayed with an enzyme immunoassay kit. The protein expression of COX-2, cPGES, and mPGES-1 was confirmed by immunoblot analysis. The following results were obtained: GER contents induced the expression of COX-2 in all five cell lines. In normal esophageal cells, cPGES, but not mPGES-1, was detected in the cytosolic fraction. GER contents induced the expression of cPGES in the microsomal fraction. In SCC cells, cPGES was expressed in the cytosolic fraction, and mPGES-1 was expressed in the microsomal fraction. GER contents induced the expression of mPGES-1 in the microsomal fraction. In ADC cells, cPGES was expressed in both the cytosolic and microsomal fractions. GER contents induced the expression of both cPGES and mPGES-1 in the microsomal fraction. In conclusion, our results suggest that GER contents induce PGE2 production in esophageal cells. However, there are different isoforms of PGES in normal cells, SCC cells, and ADC cells.

Molecular mechanisms involved in interleukin‐8 production by normal human oesophageal epithelial cells

Summary

Background

Increase in interleukin‐8 in the oesophageal mucosa has been associated with the pathogenesis of reflux oesophagitis.

Aim

To assess the effect of bile acids on the interleukin‐8 expression in normal human oesophageal epithelial cells and to determine its molecular mechanisms.

Methods

Human oesophageal epithelial cells were stimulated with unconjugated bile acids, conjugated bile acids and inflammatory cytokines. Protein and mRNA of interleukin‐8 were measured by enzyme‐linked immunosorbent assay and quantitative real‐time polymerase chain reaction, respectively. In addition, we examined protein kinases and transcription factors involved in interleukin‐8 synthetic pathways using protein kinase inhibitors and luciferase expression vectors, respectively.

Results

Unconjugated bile acids induced interleukin‐8 production from human oesophageal epithelial cells stronger than conjugated bile acids. However, conjugated bile acids in acidic media resulted in remarkable increase of interleukin‐8 production compared with those in neutral‐pH media. Mutation of the binding site of NF‐kB, AP‐1 and NF‐IL6 abrogated the induction of luciferase activities by 100%, 70% and 30%, respectively. Inhibitor of protein kinase A, protein kinase C or p38 mitogen‐activated protein kinase attenuated the production of interleukin‐8 by cholic acid.

Conclusions

These results indicate that bile acids induce interleukin‐8 expression from oesophageal epithelial cells mainly via the activation of NF‐kB as well as AP‐1.

Nicotine induces the fragile histidine triad methylation in human esophageal squamous epithelial cells

The fragile histidine triad (FHIT) gene has been proposed to have an important role in very early carcinogenesis. Methylation of the FHIT gene is associated with transcriptional inactivation in esophageal squamous cell carcinoma, and FHIT inactivation has been linked to smoking-related carcinogenesis. In this study, we confirmed methylation of the FHIT gene in human esophageal squamous epithelial cells (HEECs) and examined whether nicotine induced alteration of FHIT. Methylation status in the promoter region of the FHIT gene and p16(INK4A) gene was determined by methylation-specific PCR in HEECs exposed to nicotine under various conditions. Methylation status of the FHIT gene was confirmed by DNA-sequencing analysis. Protein expression of Fhit and the DNA methyltransferases (DNMTs) DNMT1 and DNMT3a were assessed by immunoblot analysis. In the absence of nicotine, methylation of the FHIT gene and attenuation of Fhit protein were not detected in HEECs. Nicotine induced the methylation of FHIT gene and attenuated Fhit protein in association with increased expression of DNMT3a. Reexpression of Fhit protein in HEECs was found after cessation of moderate- to long-term exposure to nicotine. Our results show that nicotine induces methylation of the FHIT gene followed by loss of Fhit protein expression in HEECs. Continuous smoking may thus increase the risk of esophageal cancer.

Chenodeoxycholic acid stimulates the progression of human esophageal cancer cells: A possible mechanism of angiogenesis in patients with esophageal cancer

Bile acids are known to promote the growth of gastrointestinal cancer. However, the underlying mechanism remains unclear. We examined whether bile acids induce tumor growth via the cyclooxygenase (COX)-2 angiogenic pathway. In vitro, esophageal squamous cell carcinoma (ESCC) cells and esophageal adenocarcinoma cells were studied. Production of prostaglandin E2 (PGE2) and vascular endothelial growth factor (VEGF) in response to treatment with chenodeoxycholic acid (CDCA) was assessed by enzyme-linked immunosorbent assay (ELISA). COX-2 protein and VEGF protein were measured by immunoblot analysis, and COX-2 activity was measured by ELISA. In vivo, CDCA was administered to ESCC cell-bearing mice. Tumor tissues were analyzed immunohistochemically, and microvessel density was evaluated. Clinically, 134 patients with ESCC who underwent esophagectomy were studied. In vitro, CDCA induced the production of PGE2 and VEGF in dose- and time-dependent manners, and these effects were attenuated by a selective COX-2 inhibitor, mitogen-activated protein kinases inhibitor, or epidermal growth factor receptor inhibitor. CDCA-induced COX-2 in the cell lysate increased the secretion of VEGF into the culture medium. In vivo, CDCA markedly enhanced tumor growth and increased vascularization. Clinically, patients whose tumors expressed both COX-2 and VEGF had poor outcomes. Our results suggest that bile acids, important constituents of duodenal fluid, stimulate the development of human esophageal cancer by promoting angiogenesis via the COX-2 pathway.

Nonsteroidal anti-inflammatory drugs and the esophageal inflammation-metaplasia-adenocarcinoma sequence

Observational studies suggest that nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of esophageal adenocarcinoma, but it is not known at what stage they may act in the esophageal inflammation-metaplasia-adenocarcinoma sequence. In an all-Ireland case-control study, we investigated the relationship between the use of NSAIDs and risk of reflux esophagitis, Barrett's esophagus, and esophageal adenocarcinoma. Patients with esophageal adenocarcinoma, long-segment Barrett's esophagus and population controls were recruited from throughout Ireland. Esophagitis patients were recruited from Northern Ireland only. Data were collected on known and potential risk factors for esophageal adenocarcinoma and on the use of NSAIDs, including aspirin, at least 1 year before interview. Associations between use of NSAIDs and the stages of the esophageal inflammation-metaplasia-adenocarcinoma sequence were estimated by multiple logistic regression. In total, 230 reflux esophagitis, 224 Barrett's esophagus, and 227 esophageal adenocarcinoma and 260 population controls were recruited. Use of aspirin and NSAIDs was associated with a reduced risk of Barrett's esophagus [odds ratio [OR; 95% confidence interval (95% CI)], 0.53 (0.31-0.90) and 0.40 (0.19-0.81), respectively] and esophageal adenocarcinoma [OR (95% CI), 0.57 (0.36-0.93) and 0.58 (0.31-1.08), respectively]. Barrett's esophagus and esophageal adenocarcinoma patients were less likely than controls to have used NSAIDs. Selection or recall bias may explain these results and the results of previous observational studies indicating a protective effect of NSAIDs against esophageal adenocarcinoma. If NSAIDs have a true protective effect on the esophageal inflammation-metaplasia-adenocarcinoma sequence, they may act early in the sequence.

Molecular mechanisms involved in interleukin‐8 production by normal human oesophageal epithelial cells

Summary

Background

Increase in interleukin‐8 in the oesophageal mucosa has been associated with the pathogenesis of reflux oesophagitis.

Aim

To assess the effect of bile acids on the interleukin‐8 expression in normal human oesophageal epithelial cells and to determine its molecular mechanisms.

Methods

Human oesophageal epithelial cells were stimulated with unconjugated bile acids, conjugated bile acids and inflammatory cytokines. Protein and mRNA of interleukin‐8 were measured by enzyme‐linked immunosorbent assay and quantitative real‐time polymerase chain reaction, respectively. In addition, we examined protein kinases and transcription factors involved in interleukin‐8 synthetic pathways using protein kinase inhibitors and luciferase expression vectors, respectively.

Results

Unconjugated bile acids induced interleukin‐8 production from human oesophageal epithelial cells stronger than conjugated bile acids. However, conjugated bile acids in acidic media resulted in remarkable increase of interleukin‐8 production compared with those in neutral‐pH media. Mutation of the binding site of NF‐kB, AP‐1 and NF‐IL6 abrogated the induction of luciferase activities by 100%, 70% and 30%, respectively. Inhibitor of protein kinase A, protein kinase C or p38 mitogen‐activated protein kinase attenuated the production of interleukin‐8 by cholic acid.

Conclusions

These results indicate that bile acids induce interleukin‐8 expression from oesophageal epithelial cells mainly via the activation of NF‐kB as well as AP‐1.

Influence of acid and bile acid on ERK activity, PPARγ expression and cell proliferation in normal human esophageal epithelial cells

AIM: To observe the effects of acid and bile acid exposure on cell proliferation and the expression of extracellular signal-regulated protein kinase (ERK) and peroxisome proliferator-activated receptor γ (PPARγ) in normal human esophageal epithelial cells in vitro.

METHODS: In vitro cultured normal human esophageal epithelial cells were exposed to acidic media (pH 4.0 - 6.5), media containing different bile acid (250 μmol/L), media containing acid and bile acid, respectively. Cell proliferation was assessed using MTT and flow cytometry. The expressions of phosphorylated ERK_1/2 and PPARγ protein were determined by the immunoblotting technique.

RESULTS: Acid-exposed (3 min) esophageal cells exhibited a significant increase in proliferation ratio, S phase of the cell cycle (P < 0.05) and the level of phosphorylated ERK_1/2 protein. When the acid-exposure period exceeded 6 min, we observed a decrease in proliferation ratio and S phase of the cell cycle, with an increased apoptosis ratio (P < 0.05). Bile acid exposure (3-12 min) also produced an increase in proliferation ratio, S phase of the cell cycle (P < 0.05) and phosphorylated ERK_1/2 expression. On the contrary, deoxycholic acid (DCA) exposure (> 20 min) decreased proliferation ratio. Compared with bile acid exposure (pH 7.4), bile acid exposure (pH 6.5, 4) significantly decreased proliferation ratio (P < 0.05). There was no expression of PPARγ in normal human esophageal epithelial cells.

CONCLUSION: The rapid stimuli of acid or bile acid increase proliferation in normal human esophageal epithelial cells by activating the ERK pathway.

Treatment of oesophageal bile reflux in children: the results of a prospective study with omeprazole

OBJECTIVES

Reflux of duodenal juice into the oesophagus has a role in the pathogenesis of both oesophageal and laryngopharyngeal inflammatory and neoplastic lesions. As little is known about effective therapy, we studied the effect of proton pump inhibitor therapy on oesophageal bile reflux in children.

METHODS

Twenty-nine children with moderate to severe erosive oesophagitis and abnormal oesophageal bile reflux were studied before and after treatment with omeprazole 1 mg/kg per day. Outcomes included a clinical symptom score, oesophageal acid and bile reflux (simultaneous 24-hour pH and Bilitec 2000 monitoring), and mucosal healing.

RESULTS

After 8 weeks of therapy, 17 (59%) of the patients were symptom-free, and 5 (17%) had minimal symptoms. Mucosal healing or reduction to low-grade oesophagitis was achieved in 25 children (86%; P < 0.0005). Mean percentages of total, upright, and supine time with oesophageal pH less than 4 were reduced from 17.0%, 16.8%, and 19.2% before treatment, to 2.83%, 3.17%, and 2.07%, respectively, after treatment (all P < 0.00001). Similarly, mean percentages of total, upright, and supine time with bile reflux were reduced from 16.96%, 12.67%, and 22.0%, to 2.27%, 1.91%, and 2.23%, respectively (P < 0.000001, P < 0.0001, and P < 0.000001, respectively).

CONCLUSIONS

Omeprazole 1 mg/kg per day is an effective therapy for the majority of children with severe erosive oesophagitis due to abnormal isolated bile reflux or combined acid and bile reflux. It remains unclear how patients with treatment-resistant bile reflux should be managed.

Roles of epidermal growth factor and Na+/H+ exchanger-1 in esophageal epithelial defense against acid-induced injury

Epidermal growth factor (EGF) is predominantly secreted by salivary glands and activates Na(+)/H(+) exchanger-1 (NHE-1), which regulates intracellular pH (pH(i)). We investigated the roles of EGF and NHE-1 in esophageal epithelial defense against acid using human esophageal epithelial cell lines and a rat chronic esophagitis model. Esophageal epithelial cells were incubated with acidified medium in the absence or presence of EGF. Cell viability and changes in pH(i) were measured. Chronic acid reflux esophagitis was induced in rats with and without sialoadenectomy. Esophageal lesion index, epithelial proliferation, and expression of EGF receptors and NHE-1 were examined. EGF protected esophageal epithelial cells against acid in a dose-dependent manner, and the cytoprotective effect of EGF was completely blocked by treatment with NHE-1 inhibitors. Tyrosine kinase, calmodulin, and PKC inhibitors significantly inhibited cytoprotection by EGF, whereas MEK, phosphatidylinositol 3-kinase, and PKA inhibitors had no effect. EGF significantly increased pH(i) recovery after NH(4)Cl pulse acidification, and this increase in pH(i) recovery was significantly blocked by inhibitors of calmodulin and PKC. Sialoadenectomy led to an increase in the severity of chronic esophagitis but affected neither epithelial proliferation nor expression of EGF receptors. Expression of NHE-1 mRNA was increased in esophagitis and upregulated in rats with sialoadenectomy. The increasing severity of esophagitis in rats with sialoadenectomy was prevented by exogenous administration of EGF. In conclusion, EGF protects esophageal epithelial cells against acid through NHE activation via Ca(2+)/calmodulin and the PKC pathway. Deficiency in endogenous EGF is associated with increased severity of esophagitis. EGF and NHE-1 play crucial roles in esophageal epithelial defense against acid.

Role of pancreatic trypsin in chronic esophagitis induced by gastroduodenal reflux in rats

BACKGROUND

Reflux of the duodenal contents with gastric acid has been reported to contribute to the development of esophageal mucosal damage and inflammation. Recent studies show that pancreatic trypsin can stimulate the production of inflammatory mediators, including chemokines and prostaglandins from human esophageal epithelial cells in vitro. The aim of the present study was to investigate the role of pancreatic trypsin in the pathogenesis of chronic esophageal inflammation induced by gastroduodenal reflux in rats.

METHODS

Esophagogastroduodenal anastomosis was carried out in male Wistar rats by anastomosing the jejunum to the gastroesophageal junction under diethyl ether inhalation anesthesia. The animals undergoing surgery were treated with the control diet, rabeprazole sodium, nizatidine, ecabet sodium, camostat mesilate (CMM), ONO-1714, a specific inducible nitric oxide synthase (iNOS) inhibitor, or meloxicam, a selective cyclooxygenase-2 (COX-2) inhibitor. Esophageal injury was evaluated by macroscopic and microscopic findings, and mRNA expression for CINC-1, COX-2, and iNOS was determined by real-time polymerase chain reaction (PCR). Trypsin activity within the esophageal lumen was measured 2 weeks after surgery, and the expression of protease-activated receptor (PAR)-1 and -2 was confirmed by reverse transcription (RT)-PCR.

RESULTS

At 8 weeks after surgery, gastroduodenal reflux induced esophageal erosions and ulcer formation as well as marked thickening of the esophageal wall. Histological study showed an increase of thickness of the esophageal mucosa, hyperplasia of the epidermis and basal cells, ulcer formation, and marked infiltration of inflammatory cells. The macroscopic ulcer score and histological ulcer length were significantly reduced by treatment with rabeprazole or CMM but not by nizatidine or ecabet sodium, compared with each control. Rabeprazole, nizatidine, or ecabet sodium did not affect the severity of mucosal hyperplastic scores or histological parameters in esophagitis. In contrast, the CMM group showed a significant decrease in the mucosal hyperplastic and inflammatory scores. The enhanced expression of CINC-1, COX-2, and iNOS mRNA in the control group was also markedly inhibited in the CMM-treated group. ONO-1714 or meloxicam treatment significantly reduced the macroscopic scores of ulcer and hyperplasia. The trypsin activity in the esophageal lumen was significantly increased in the control diet group, and this increase was significantly inhibited in the CMM-treated group. The expression of PAR-1 and -2 mRNA was confirmed in rat esophageal epithelium.

CONCLUSIONS

With this model, we have demonstrated that CMM significantly reduces inflammation and hyperplasia in the esophageal mucosa. These results indicate that trypsin, which is primarily inhibited by CMM, plays an important role in the mucosal damage induced by gastroduodenal reflux and that it can be a therapeutic target in patients with gastroduodenal reflux esophagitis.

Expression of proteinase-activated receptor 2 on human primary gastrointestinal myofibroblasts and stimulation of prostaglandin synthesis

It is known that subepithelial myofibroblast-derived prostaglandin (PG)E2 can regulate intestinal epithelial cell functions, and that proteinase-activated receptor-2 (PAR2) is abundantly expressed in the gastrointestinal tract. Since PAR2 activation has previously been associated with stimulation of PGE2 synthesis, we hypothesized that PAR2 expressed on primary human gastrointestinal myofibroblasts regulates PGE2 synthesis via cyclooxygenase (COX)-1 and (or) COX-2, and associated PGE synthases. Primary human myofibroblasts were isolated from the resection tissue of the esophagus, small intestine, and colon. Expression of functional PAR2 was determined by RT-PCR and by calcium mobilization in Fura-2/AM-loaded cells. Trypsin and the selective PAR2-activating peptide (PAR2-AP) SLIGRL-NH2 stimulated PGE2 synthesis in a concentration-dependent manner, as measured by enzyme immunoassay. Selective COX inhibition showed PAR2-induced PGE2 synthesis to be COX-1 dependent in esophageal myofibroblasts and both COX-1 and COX-2 dependent in colonic cells, consistent with the distribution of COX-1 and COX-2 expression. Although both cytosolic and microsomal PGE synthases were expressed in cells from all tissues, microsomal PGE synthases were expressed at highest levels in the colonic myofibroblasts. Activation of PAR2 on gastrointestinal myofibroblasts stimulates PGE2 synthesis via different pathways in the colon than in the esophagus and small intestine.

Bile salts inhibit growth and induce apoptosis of culture human normal esophageal mucosal epithelial cells

AIM: To investigate the effect of six bile salts: glycocholate (GC), glycochenodeoxycholate (GCDC), glycodeoxycholate (GDC), taurocholate (TC), taurochenodeoxycholate (TCDC), taurodeoxycholate (TDC), and their mixture on cultured human normal esophageal mucosal epithelial cells.

METHODS: Human normal esophageal mucosal epithelial cells were cultured with serum-free keratinocyte medium. 3-[4,5-Dimethylthiaolyl]-2,5-diphenyl-tetrazolium bromide assay was applied to the detection of cell proliferation. Apoptotic morphology was observed by phase-contrast video microscopy and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Sub-G1 DNA fragmentations and early apoptotic cells were assayed by flow cytometry (FCM) with propidium iodide (PI) staining and annexin V-FITC conjugated with PI staining. Apoptotic DNA ladders on agarose gel electrophoresis were observed.

RESULTS: Except for GC, GCDC, GDC, TC, TCDC, TDC and their mixture could initiate growth inhibition of esophageal mucosal epithelial cells in a dose- and time-dependent manner. TUNEL and FCM assays demonstrated that the bile salts at 500 μmol/L and their mixture at 1 500 μmol/L induced apoptosis except for GC. The percentage of sub-G1 detected by FCM with PI staining was 83.5% in cells treated with 500 μmol/L TC for 2 h, and 19.8%, 20.4%, 25.6%, 13.5%, and 75.8% in cells treated with 500 μmol/L GCDC, TCDC, GDC, TDC, and 1 500 μmol/L mixture for 24 h, respectively, which were higher than that of the control (1.5%). The percentage was 1.4% in cells with 500 μmol/L GC for 24 h. DNA ladders on agarose gel electrophoresis were seen in cells treated with 500 μmol/L TC for 2 h and 1 500 μmol/L mixture for 24 h.

CONCLUSION: All GCDC, GDC, TC, TCDC, TDC and their mixture can inhibit growth and induce apoptosis of cultured human normal esophageal mucosal epithelial cells, but GC is well tolerated by the cells.

Low pH induces co-ordinate regulation of gene expression in oesophageal cells

The development of gastro-oesophageal reflux disease (GORD) is known to be a causative risk factor in the evolution of adenocarcinoma of the oesophagus. The major component of this reflux is gastric acid. However, the impact of low pH on gene expression has not been extensively studied in oesophageal cells. This study utilizes a transcriptomic and bioinformatic approach to assess regulation of gene expression in response to low pH. In more detail, oesophageal adenocarcinoma cell lines were exposed to a range of pH environments. Affymetrix microarrays were used for gene-expression analysis and results were validated using cycle limitation and real-time RT-PCR analysis, as well as northern and western blotting. Comparative promoter transcription factor binding site (TFBS) analysis (MatInspector) of hierarchically clustered gene-expression data was employed to identify the elements which may co-ordinately regulate individual gene clusters. Initial experiments demonstrated maximal induction of EGR1 gene expression at pH 6.5. Subsequent array experimentation revealed significant induction of gene expression from such functional categories as DNA damage response (EGR1-4, ATF3) and cell-cycle control (GADD34, GADD45, p57). Changes in expression of EGR1, EGR3, ATF3, MKP-1, FOSB, CTGF and CYR61 were verified in separate experiments and in a variety of oesophageal cell lines. TFBS analysis of promoters identified transcription factors that may co-ordinately regulate gene-expression clusters, Cluster 1: Oct-1, AP4R; Cluster 2: NF-kB, EGRF; Cluster 3: IKRS, AP-1F. Low pH has the ability to induce genes and pathways which can provide an environment suitable for the progression of malignancy. Further functional analysis of the genes and clusters identified in this low pH study is likely to lead to new insights into the pathogenesis and therapeutics of GORD and oesophageal cancer.