Hypoxia-inducible factor-1α mediates reflux-induced epithelial-mesenchymal plasticity in Barrett's oesophagus patients.

INTRODUCTION: Epithelial-mesenchymal plasticity (EMP), the process through which epithelial cells acquire mesenchymal features, is needed for wound repair but also might contribute to cancer initiation. Earlier, in vitro studies showed that Barrett's cells exposed to acidic bile salt solutions (ABS) develop EMP. Now, we have (1) induced reflux oesophagitis in Barrett's oesophagus (BO) patients by stopping proton pump inhibitors (PPIs), (2) assessed their biopsies for EMP and (3) explored molecular pathways underlying reflux-induced EMP in BO cells and spheroids. METHODS: 15 BO patients had endoscopy with biopsies of Barrett's metaplasia while on PPIs, and 1 and 2 weeks after stopping PPIs; RNA-seq data were assessed for enrichments in hypoxia-inducible factors (HIFs), angiogenesis and EMP pathways. In BO biopsies, cell lines and spheroids, EMP features (motility) and markers (vascular endothelial growth factor (VEGF), ZEB1, miR-200a&b) were evaluated by morphology, migration assays, immunostaining and qPCR; HIF-1α was knocked down with siRNA or shRNA. RESULTS: At 1 and/or 2 weeks off PPIs, BO biopsies exhibited EMP features and markers, with significant enrichment for HIF-1α, angiogenesis and EMP pathways. In BO cells, ABS induced HIF-1α activation, which decreased miR-200a&b while increasing VEGF, ZEB1 and motility; HIF-1α knockdown blocked these effects. After ABS treatment, BO spheroids exhibited migratory protrusions showing nuclear HIF-1α, increased VEGF and decreased miR-200a&b. CONCLUSIONS: In BO patients, reflux oesophagitis induces EMP changes associated with increased HIF-1α signalling in Barrett's metaplasia. In Barrett's cells, ABS trigger EMP via HIF-1α signalling. Thus, HIF-1α appears to play a key role in mediating reflux-induced EMP that might contribute to cancer in BO. TRIAL REGISTRATION NUMBER: NCT02579460.

In females, salivary secretion was significantly lower in patients with severe reflux esophagitis than in healthy controls.

BACKGROUND: The salivary secretion in patients with mild reflux esophagitis (RE) and non-erosive reflux disease is significantly lower in females, but not in males. However, sex differences in salivary secretion in patients with severe RE remain unknown. Therefore, the present study investigated sex differences in saliva secretion in patients with severe RE. METHODS: Subjects consisted of 23 male patients with severe RE, 24 male healthy controls (HCs), 26 female patients with severe RE, and 25 female HCs. Saliva secretion was assessed as follows: each patient chewed sugarless gum for 3 min prior to endoscopy, and the amount and pH of saliva secreted before and after acid loading as an index of the acid-buffering capacity were measured. RESULTS: In males, no significant differences were observed in the amount of saliva secretion, salivary pH, or the acid-buffering capacity between severe RE patients and HCs. In females, the amount of saliva secretion (severe RE: 2.4 [1.8-4.1], HCs: 5.3 [3.4-7.5], p = 0.0017), salivary pH (severe RE: 7.0 [6.7-7.3], HCs: 7.2 [7.1-7.3], p = 0.0455), and the acid-buffering capacity (severe RE: 5.9 [5.3-6.2], HCs: 6.2 [6.1-6.5], p = 0.0024) were significantly lower in severe RE patients than in HCs. CONCLUSION: Among females, the salivary secretion was significantly lower in severe RE patients than in HCs. This reduction in salivary secretion may contribute to the pathophysiology of severe RE in females.

Obesity and its effects on the esophageal mucosal barrier.

Obesity is associated with gastroesophageal reflux disease (GERD) and its complications including reflux esophagitis, Barrett's esophagus, and esophageal adenocarcinoma. Traditionally, these associations have been attributed to the mechanical effect of abdominal fat in increasing intra-abdominal pressure, thereby promoting gastroesophageal reflux and causing disruption of antireflux mechanisms at the esophagogastric junction. However, recent studies suggest that visceral adipose tissue (VAT) produces numerous cytokines that can cause esophageal inflammation and impair esophageal mucosal barrier integrity through reflux-independent mechanisms that render the esophageal mucosa especially susceptible to GERD-induced injury. In this report, we review mechanisms of esophageal mucosal defense, the genesis and remodeling of visceral adipose tissue during obesity, and the potential role of substances produced by VAT, especially the VAT that encircles the esophagogastric junction, in the impairment of esophageal mucosal barrier integrity that leads to the development of GERD complications.

Impact of bile acids on the severity of laryngo-pharyngeal reflux.

OBJECTIVES: The primary end point of this study was to evaluate the impact of bile acids on severity of laryngo-pharyngeal reflux (LPR) and the possible correlation with esophagitis and upper airway malignancies. The second end point was to evaluate if salivary bile acids and molecules other than pepsin might serve as diagnostic biomarkers of LPR. DESIGN: Observational prospective comparative study. SETTING: Otorhinolaryngology unit of a tertiary hospital. PARTICIPANTS: Sixty-two consecutive adult outpatients suspected of LPR. MAIN OUTCOME MEASURES: Bile acids, bilirubin and pepsinogen I-II were measured in saliva. Patients underwent pH metry and based on the results of bile acids were subdivided as acid, mixed and alkaline LPR. RESULTS: Significantly higher Reflux Findings Score (RFS) and Reflux Symptoms Index (RSI) were seen in patients with alkaline and mixed LPR compared to acid LPR. Salivary bile acids >1 µmol/L seem to be a reliable indicator of the severity of LPR. Compared to those without, patients with esophagitis or a history of upper airway malignancy have high concentrations of bile acids in saliva. Among the molecules studied, bile acids were the most suitable for diagnosis of LPR, with a sensitivity of 86% and a positive predictive value of 80.7%. CONCLUSIONS: Our data suggest that high concentrations of bile acids are associated with higher values of RSI and RFS in LPR as well as a higher risk of esophagitis and history of upper airway malignancies. We finally observed that bile acids provided the best biometric parameters for diagnosis of LPR among the molecules tested.

Leptin Aggravates Reflux Esophagitis by Increasing Tissue Levels of Macrophage Migration Inhibitory Factor in Rats.

Leptin, produced primarily by the adipose tissue, acts as a pro-inflammatory modulator, thereby contributing to the development of obesity-related disease. Although high levels of leptin in the obese are closely related to gastroesophageal reflux disease, the mechanism by which leptin influences esophageal inflammation remains unknown. Macrophage migration inhibitory factor (MIF) is produced by immune cells, such as T lymphocytes and macrophages, and MIF is known to induce the production of tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß) and interleukin 6 (IL-6). We therefore investigated the mechanism whereby leptin aggravates reflux esophagitis, by focusing on esophageal tissue levels of MIF and CD3+ T lymphocytes, both of which are crucial for the reflux-induced epithelial damage. Esophageal inflammation was surgically induced in male Wistar rats by ligating the forestomach and narrowing the duodenum to facilitate gastroesophageal reflux, followed by administration of leptin or vehicle with an osmotic pump system for 1 week. We demonstrated that the administration of leptin exacerbated the reflux esophagitis with the apparent infiltration of CD3+ T lymphocytes and caused the significant increase in the esophageal tissue levels of MIF. Moreover, the leptin caused increases in the esophageal tissue levels of TNF-α, IL-1ß and IL-6, downstream targets of MIF. Importantly, the increases in these pro-inflammatory cytokines were accompanied by increased protein levels of phospho-STAT3 and phospho-AKT, pivotal molecules of leptin signaling pathways. In conclusion, through enhancing the MIF-induced inflammatory signaling, leptin could contribute to the development of gastroesophageal reflux disease.

Hypoxia-inducible factor-2α plays a role in mediating oesophagitis in GORD.

OBJECTIVE: In an earlier study wherein we induced acute reflux by interrupting proton pump inhibitor (PPI) therapy in patients with reflux oesophagitis (RO) healed by PPIs, we refuted the traditional concept that RO develops as an acid burn. The present study explored our alternative hypothesis that RO results from reflux-stimulated production of pro-inflammatory molecules mediated by hypoxia-inducible factors (HIFs). DESIGN: Using oesophageal biopsies taken from patients in our earlier study at baseline and at 1 and 2 weeks off PPIs, we immunostained for HIF-1α, HIF-2α and phospho-p65, and measured pro-inflammatory molecule mRNAs. We exposed human oesophageal squamous cell lines to acidic bile salts, and evaluated effects on HIF activation, p65 function, pro-inflammatory molecule production and immune cell migration. RESULTS: In patient biopsies, increased immunostaining for HIF-2α and phospho-p65, and increased pro-inflammatory molecule mRNA levels were seen when RO redeveloped 1 or 2 weeks after stopping PPIs. In oesophageal cells, exposure to acidic bile salts increased intracellular reactive oxygen species, which decreased prolyl hydroxylase function and stabilised HIF-2α, causing a p65-dependent increase in pro-inflammatory molecules; conditioned media from these cells increased T cell migration rates. HIF-2α inhibition by small hairpin RNA or selective small molecule antagonist blocked the increases in pro-inflammatory molecule expression and T cell migration induced by acidic bile salts. CONCLUSIONS: In patients developing RO, increases in oesophageal HIF-2α correlate with increased pro-inflammatory molecule expression. In oesophageal epithelial cells, acidic bile salts stabilise HIF-2α, which mediates expression of pro-inflammatory molecules. HIF-2α appears to have a role in RO pathogenesis. TRIAL REGISTRATION NUMBER: NCT01733810; Results.

A novel murine model of esophageal nonerosive reflux disease: from inflammation to impairment in mucosal integrity.

Nonerosive reflux disease (NERD) is a highly prevalent phenotype of the gastroesophageal reflux disease. In this study, we developed a novel murine model of NERD in mice with microscopic inflammation and impairment in the epithelial esophageal barrier. Female Swiss mice were subjected to the following surgical procedure: the transitional region between the forestomach and the glandular portion of the stomach was ligated, and a nontoxic ring was placed around the duodenum near the pylorus. The control group underwent sham surgery. The animals were euthanized at 1, 3, 7, and 14 days after surgery. Survival and body weight were monitored daily. Esophageal wet weight, macroscopic lesion, histopathological alterations, myeloperoxidase (MPO) activity, cytokine levels, transepithelial electrical resistance (TEER), and mucosal permeability were evaluated. The survival rate was 78% at 14 days, with mild loss in body weight. Surgery did not induce erosive esophagitis but instead induced microscopic inflammation and increased esophageal wet weight, IL-6, keratinocyte-derived cytokine (KC) levels, and MPO activity with maximal peak between 3 and 7 days and resolution at 14 days postsurgery. Epithelial esophageal barrier was evaluated in operated mice at 7 and 14 days postsurgery; a decrease in TEER and increase in the esophageal epithelial permeability were observed compared with the sham-operated group. In addition, the inhibition of acid secretion with omeprazole significantly prevented the esophageal inflammation and impairment of barrier function at 7 days postsurgery. Thus we established a novel experimental model of NERD in mice, which can contribute to understanding the pathophysiological events associated with NERD.NEW & NOTEWORTHY In this study, we standardized an experimental model of nonerosive reflux disease (NERD) in mice. This model involves an acute inflammatory response followed by impaired esophageal mucosal integrity, even in the absence of inflammation. Thus this model can serve for evaluation of pathophysiological aspects of NERD and open new perspectives for therapeutic strategies for patients with this disorder.

Effects of Different Ratio of n-6/n-3 Polyunsaturated Fatty Acids on the PI3K/Akt Pathway in Rats with Reflux Esophagitis.

BACKGROUND We designed this study to investigate the influence of different ratios of n-6/n-3 polyunsaturated fatty acid in the diet of reflux esophagitis (RE) rats' and the effect on the PI3K/Akt pathway. MATERIAL AND METHODS RE rats were randomly divided into a sham group and modeling groups of different concentrations of n-6/n-3 polyunsaturated fatty acid (PUFA): 12:1 group, 10:1 group, 5:1 group, and 1:1 group. RT-PCR and Western-blot were used to detect the expression of PI3K, Akt, p-Akt, NF-κBp50, and NF-κBp65 proteins in esophageal tissue. RESULTS In the n-6/n-3 PUFAs groups the expression of PI3K, Akt, p-Akt, nf-κbp50, and NF-κBp65 mRNA decreased with the decrease in n-6/n-3 ratios in the diet. The lowest expression of each indicator occurred in the 1:1 n-6/n-3 group compared with other n-6/n-3 groups, the difference was statistically significant (p<0.05). CONCLUSIONS The inhibition of n-3 PUFAs in the development of esophageal inflammation in rats with RE was attributed to the function of PI3K/Akt-NF-κB signaling pathway.

Oesophageal intrasquamous IgG4 deposits: an adjunctive marker to distinguish eosinophilic oesophagitis from reflux oesophagitis.

AIMS: To explore the utility of an IgG4 immunohistochemical stain to help distinguish eosinophilic oesophagitis from gastroesophageal reflux disease. METHODS AND RESULTS: We examined 21 cases of eosinophilic oesophagitis and 25 cases of gastroesophageal reflux disease. The diagnosis of eosinophilic oesophagitis was based on the presence of oesophageal dysfunction, >15 eosinophils per high-power field, and a lack of response to proton pump inhibitors. Gastroesophageal reflux disease showed intraepithelial eosinophils, but a clinical and/or histological response to proton pump inhibitor therapy. We also evaluated an additional cohort of 22 cases with intraepithelial eosinophils. Immunohistochemical staining for IgG4 was performed. Sixteen of 21 (76%) eosinophilic oesophagitis cases showed intrasquamous extracellular IgG4 deposits, whereas all 25 gastroesophageal reflux disease cases were negative. Mucosal IgG4-positive plasma cells were identified in eosinophilic oesophagitis and gastroesophageal reflux disease cases in 58% and 40% of cases, respectively. Eosinophilic oesophagitis patients receiving treatment were less likely to be positive for intraepithelial IgG4 deposits (88% versus 53%). In the validation cohort, the sensitivity and specificity for eosinophilic oesophagitis were 88% and 100%, respectively. CONCLUSIONS: The presence of intrasquamous IgG4 deposits is a useful adjunctive marker in the distinction between eosinophilic oesophagitis and gastroesophageal reflux disease.

Estrogen Enhances Esophageal Barrier Function by Potentiating Occludin Expression.

BACKGROUND: We recently demonstrated that a female sex hormone, estrogen, suppressed esophageal epithelial injury in a reflux esophagitis model of rat, suggesting that estrogen may play an important role in controlling the progress of the gastro-esophageal reflux disease spectrum. However, the precise mechanism of the action is unclear. AIM: To investigate the potential role of estrogen in the esophageal barrier function. METHODS: Male rabbits were pretreated with either continuous release 17ß-estradiol or placebo, and the excised esophageal mucosa was subjected to Ussing chamber experiments after the 2-week pre-treatment. The mucosal side of the chamber was perfused with luminal irritants (HCl or acidified sodium nitrite), while the basal side was perfused by modified Krebs buffer. The epithelial barrier function was evaluated by the transmembrane resistance and the epithelial permeability. The intercellular space of the epithelium was investigated with transmission electron microscopy and the expression of tight junction protein, occludin, claudin-1, and claudin-4, with immunoblotting. RESULTS: Estrogen pre-treatment significantly attenuated the decrease in the transmembrane resistance and the increase in the epithelial permeability induced by luminal irritants. Furthermore, the dilation of the intercellular space induced by luminal HCl was significantly alleviated by 17ß-estradiol administration. The baseline occludin expression was significantly potentiated by 17ß-estradiol administration. CONCLUSIONS: This is the first study showing an enhancement of the esophageal barrier function by 17ß-estradiol administration. The lack of the protective effect of estrogen could be responsible for the male predominance of erosive reflux esophagitis.

The effect of n-3/n-6 polyunsaturated fatty acids on acute reflux esophagitis in rats.

BACKGROUND: Polyunsaturated fatty acids (PUFAs) play various roles in inflammation. However, the effect of PUFAs in the development of reflux esophagitis (RE) is unclear. This study is to investigate the potential effect of n-3/n-6 PUFAs on acute RE in rats along with the underlying protective mechanisms. METHODS: Forty Sprague Dawley rats were randomly divided into four groups (n = 10 in each group). RE model was established by pyloric clip and section ligation. Fish oil- and soybean oil-based fatty emulsion (n-3 and n-6 groups), or normal saline (control and sham operation groups) was injected intraperitoneally 2 h prior to surgery and 24 h postoperatively (2 mL/kg, respectively). The expressions of interleukin (IL)-1ß, IL-8, IL-6 and myeloid differentiation primary response gene 88 (MyD88) in esophageal tissues were evaluated by Western blot and immunohistochemistry after 72 h. The malondialdehyde (MDA) and superoxide dismutase (SOD) expression in the esophageal tissues were determined to assess the oxidative stress. RESULTS: The mildest macroscopic/microscopic esophagitis was found in the n-3 group (P < 0.05). The expression of IL-1ß, IL-8, IL-6 and MyD88 were increased in all RE groups, while the lowest and highest expression were found in n-3 and n-6 group, respectively (P < 0.05). The MDA levels were increased in all groups (P < 0.05), in an ascending trend from n-3, n-6 groups to control group. The lowest and highest SOD levels were found in the control and n-3 group, respectively (P < 0.05). CONCLUSION: n-3 PUFAs may reduce acute RE in rats, which may be due to inhibition of the MyD88-NF-kB pathway and limit oxidative damage.

[DAILY INTRAESOPHAGEAL pH-MONITORING IN THE DIAGNOSIS OF THE SEVERITY OF ESOPHAGITIS WITH GASTROESOPHAGEAL REFLUX DISEASE].

OBJECTIVE: To identify criteria of pH-grams to diagnose the severity of esophagitis and preneoplastic complications of GERD. MATERIALS AND METHODS: 63 patients aged from 18 to 70 with A, B, C degree of GERD, according to the Los Angeles classification and 15 patients with intestinal metaplasia of columnar epithelium and leukoplakia of the stratified squamous epithelium of the esophagogastric transition were examined. For daily intraesophageal pH-monitoring "Gastroscan-24", pH probes manufactured by ZAO NPP "Istok- system", Fryazino (Russia) were used. pH-grams were estimated according for indicators DeMeester. Endoscopy was performed by videoesofagogastroscopes of Evis Exera- system--160 and by the tools company "Olympus" (Japan). RESULTS: 5 options of pH-grams were selected, each of them may correspond to some degree of esophagitis, preneoplastic changes of the esophageal mucosa, esophageal and extraesophageal manifestations of GERD. CONCLUSION: Daily pH-monitoring of the esophagus can serve as a screening for the severity of esophagitis, preneoplastic changes of esophagogastric transition, for addressing the need of morphological studies and differential diagnosis of extraesophageal manifestations of GERD.

Dickkopf-1, the Wnt antagonist, is induced by acidic pH and mediates epithelial cellular senescence in human reflux esophagitis.

Squamous esophageal epithelium adapts to acid reflux-mediated injury by proliferation and differentiation via signal transduction pathways. Induction of the Wnt antagonist Dickkopf-1 (Dkk1) is involved in tissue repair during inflammation and cellular injury. In this study, we aimed to identify the biological role of Dkk1 in human reflux esophagitis with respect to cell growth and regulation of Wnt signaling. Esophageal biopsies from reflux-esophagitis patients (n = 15) and healthy individuals (n = 10) were characterized in terms of Dkk1 expression. The role of Dkk1 in response to acid-mediated epithelial injury was analyzed by cellular assays in vitro utilizing squamous esophageal epithelial cell lines (EPC1-hTERT, EPC2-hTERT, and HEEC). Dkk1 was significantly overexpressed in human reflux-esophagitis tissue compared with healthy esophageal mucosa at transcriptional and translational levels. After acute and chronic acid (pH 4) exposure, esophageal squamous epithelial cell lines expressed and secreted high levels of Dkk1 in response to stress-associated DNA injury. High extracellular levels of human recombinant Dkk1 inhibited epithelial cell growth and induced cellular senescence in vitro, as demonstrated by reduced cell proliferation, G0/G1 cell cycle arrest, elevated senescence-associated ß-galactosidase activity, and upregulation of p16. Acid pulsing induced Dkk1-mediated senescence, which was directly linked to the ability of Dkk1 to antagonize the canonical Wnt/ß-catenin signaling. In healthy esophageal mucosa, Dkk1 expression was associated with low expression of transcriptionally active ß-catenin, while in reflux-esophagitis tissue, Dkk1 overexpression correlated with increased senescence-associated ß-galactosidase activity and p16 upregulation. The data indicate that, in human reflux esophagitis, Dkk1 functions as a secreted growth inhibitor by suppressing Wnt/ß-catenin signaling and promoting cellular senescence. These findings suggest a significant role for Dkk1 and cellular senescence in esophageal tissue homeostasis during reflux esophagitis.

[The role of psycho-autonomic status and the serotonergic system in patients with gastroesophageal reflux disease].

OBJECTIVE: Identify the differences of the autonomic nervous system (ANS), serotonin levels, cognitive, behavioral and emotsinalnoy areas in groups of patients with reflux esophagitis (RE) and non-erosive reflux disease (NERD) and assess the impact on the disease. MATERIALS AND METHODS: The study included 71 patients rith gastroesophageal reflux disease (GERD), including 29 patients with ER, 42--NERD. Diagnosis was based on anamnesis, clinical research, fibrogastrocopy, pH-metry. Tested with a scale situational and personal anxiety Spielberg Hanina, diagnostic techniques and forms of aggression indicators A. Bass and A. Dark, the Toronto aleksitimicheskoy scale method for investigating the level of subjective control, clinical questionnaire for the identification and evaluation of neurotic states, personality questionnaire Bekhterevsky Institute, cardiointervalography, orthoklinostatik and cold test, determined the level of serotonin in the blood. RESULTS: Compared with the group of patients suffering from ER patients with NERD determined by the displacement in the direction of internality measure locus of control personality, and patients with ER, in contrast, had lower locus of control personality, a high level of situational anxiety, irritability, anxiety type of attitude to the situation of the disease associated with impaired autonomic software ANS activity. CONCLUSION: Patients with ER are more pronounced changes in cognitive-emotional sphere may have an impact on the course of disease and requiring psychological, medical correction.

Gender differences in oesophageal mucosal injury in a reflux oesophagitis model of rats.

OBJECTIVE: There is a strong male predominance of oesophageal adenocarcinoma, which might be related to the higher prevalence of precursor lesions such as erosive reflux oesophagitis in men compared with women. This experiment investigated the gender difference in a reflux oesophagitis model of rats and explored the potential role of oestrogen in controlling oesophageal tissue damage. DESIGN: An acid-reflux oesophagitis model was surgically produced in male and female rats, and ascorbic acid in the diet and sodium nitrite in the drinking water were administered to half of either group to provoke luminal exogenous nitric oxide (NO) as an exacerbating agent. Seven days after the surgery, the oesophagus was excised, and the injury area, myeloperoxidase activity and pro-inflammatory cytokine levels were measured. Furthermore, 17ß-oestradiol was administered to ovariectomised female rats or male rats, which then underwent reflux oesophagitis surgery. RESULTS: While there was no gender difference in oesophageal damage in the baseline model, oesophageal damage was more intensively observed in males than in females in the presence of exogenous NO administration. While oesophageal damage was increased in ovariectomised rats compared with sham ovariectomised, exacerbated oesophageal damage was attenuated by the replacement of 17ß-oestradiol. In addition, exacerbated oesophageal damage in male rats was suppressed by 17ß-oestradiol. CONCLUSION: This is the first study showing the prominent gender difference in the severity of oesophageal tissue damage in a gastro-oesophageal reflux disease-related animal model, highlighting the critical involvement of oestrogen in controlling gastro-oesophageal reflux disease-related oesophageal epithelial injury.

Xuanfu Daizhe Tang alleviates reflux esophagitis in rats by inhibiting the STAT1/TREM-1 pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Reflux esophagitis (RE) is a common chronic inflammatory disease of the esophageal mucosa with a high prevalence and recurrence rate, for which a satisfactory therapeutic strategy is still lacking. Chinese medicine has its characteristics and advantages in treating RE, and the clinical application of Xuanfu Daizhe Tang (XDT) in treating RE has achieved sound therapeutic effects. However, there needs to be more research on its mechanism of action. AIM OF THE STUDY: The present work aimed to investigate the mechanism of XDT action in RE through the Signal Transducer and Activator of Transcription 1 (STAT1)/Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) pathway. MATERIALS AND METHODS: The main active components of XDT were analyzed by ultra-performance liquid chromatography-mass spectrometer (UPLC-MS). The effect of XDT on RE was evaluated in a rat model of RE induced by "Cardioplasty + pyloric ligation + Roux-en-Y esophagojejunostomy". Each administration group was treated by gavage. The degree of damage to the esophageal mucosa was evaluated by visual observation, and the Potential of Hydrogen (PH) method and Hematoxylin-eosin staining (HE) staining were performed. Serum levels of Interleukin-1ß (IL-1ß), Interleukin-6 (IL-6), Tumor Necrosis Factor alpha (TNF-α), and Inducible Nitric Oxide Synthase (iNOS) were measured by ELISA. Quantitative Real-time PCR (qPCR), Western Blot (WB), and Immunofluorescence (IF) methods were used to detect Claudin-4, Claudin-5, TREM-1, and p-STAT1 in esophageal tissues for studying the mechanism of action and signaling pathway of XDT. Immunohistochemistry (IHC) analysis was used to detect the expression of TREM-1 and CD68 in esophageal tissues. Flow Cytometry (FC) was used to detect the polarization of macrophages in the blood. After conducting preliminary experiments to verify our hypothesis, we performed molecular docking between the active component of XDT and STAT1 derived from rats and parallel experiments with STAT1 inhibitor. The selective increaser of STAT1 transcription (2-NP) group was used to validate the mechanism by which XDT acts. RESULTS: XDT alleviated esophageal injury and attenuated histopathological changes in RE rats. XDT also inhibited the inflammatory response and decreased serum IL-1ß, IL-6, TNF-α, and iNOS levels in RE rats. qPCR and WB results revealed that XDT inhibited the expression of Claudin-4, Claudin-5, TREM-1, and STAT1 in the esophageal mucosa of RE rats. IHC and FC results showed that XDT reduced TREM-1 levels in esophageal tissues and polarized macrophages toward M2. The molecular docking results showed that rat-derived STAT1 can strongly bind to Isochronogenic acid A in XDT. The parallel experimental results of STAT1 inhibitor showed that XDT has anti-inflammatory effects similar to STAT1 inhibitors. The 2-NP group confirmed that XDT exerts its therapeutic effect on reflux esophagitis through the STAT1/TREM-1 pathway, with STAT1 as the upstream protein. CONCLUSIONS: This study suggests that XDT may treat reflux esophagitis by modulating the STAT1/TREM-1 pathway.

Histology of symptomatic gastroesophageal reflux disease: is it predictive of response to proton pump inhibitors?

BACKGROUND AND AIM: To examine the differences in esophageal histopathology between non-erosive reflux disease (NERD) and reflux esophagitis (RE), and to investigate whether baseline esophageal histopathology can predict the therapeutic response to proton pump inhibitors (PPIs). METHOD: The subjects comprised 94 patients with NERD (n = 71) or mild RE (n = 23). Tissue was biopsied from 5 cm above the squamo-columnar junction (SCJ), and the degree or presence of nine histopathological markers was assessed. The patients were treated with rabeprazole (RPZ) 10 mg once daily for 4 weeks. If complete heartburn relief was not achieved, RPZ was increased to 10 mg twice daily for another 2 weeks, and then to 20 mg twice daily for another 2 weeks if heartburn remained. RESULTS: Features of esophageal histopathology 5 cm above the SCJ differed between NERD and RE patients. The esophageal histopathology in patients unresponsive to RPZ was characterized by Protein Gene Product (PGP) 9.5 negativity in those with NERD, and intraepithelial bleeding in those with RE. In addition, the combination of dilated intercellular spaces (DIS) (+)/PGP 9.5 (-) was indicative of strong resistance to PPI therapy in NERD patients. CONCLUSION: The therapeutic efficacy of PPI can be predicted from the features of biopsied esophageal tissue. Factors predictive of resistance to treatment with PPI are negativity for PGP 9.5 in NERD patients and intraepithelial bleeding in RE patients.

Increased expression of endothelin-1 and endothelin receptor A in reflux esophagitis and Barrett's esophagus.

Barrett's esophagus (BE) is considered a complication of the inflammation provoked by acid and bile reflux. Endothelin-1 (ET-1) expresses in various cells during inflammatory process. However, the role of ET-1 in human inflamed and uninflamed esophageal tissue is unknown. The present study aimed to examine the expression of ET-1 and its receptors in human reflux esophagitis (RE) and BE. Endoscopic biopsies of normal squamous epithelium (NSE) (n = 20), RE (n = 22), and long segment BE (n = 14) were obtained. The segmental degree of endoscopic and histopathological inflammation was graded, and immunohistochemistry and real-time quantitative polymerase chain reaction were used to determine the expression of ET-1 and endothelin receptor A (ET(A)R) and endothelin receptor B (ET(B)R). ET-1 and ET(A)R messenger RNA (mRNA) levels were higher in RE than in NSE (3.25 ± 1.78 vs. 1.10 ± 0.71, P = 0.000; 2.13 ± 1.06 vs. 1.12 ± 0.64, P = 0.001, respectively). In BE, relative ET-1 mRNA levels in the proximal segment were higher than in the distal segment (3.03 ± 1.83 vs. 1.16 ± 0.70, P = 0.004) and in normal esophageal epithelium (P = 0.002). There was no significantly difference of ET(A)R mRNA levels between the proximal segment and the distal segment (1.99 ± 1.28 vs. 1.14 ± 0.67, P = 0.072). ET(B)R mRNA expression was unaltered between the groups. Furthermore, immunohistochemistry demonstrated that ET-1 expression increased significantly in RE (51.18 ± 30.14) compared with those in NSE (21.10 ± 18.17, P = 0.000) and in distal BE segment (28.02 ± 24.92, P = 0.022). There were more ET-1 positive cells in proximal BE segment (50.07 ± 25.88) than in distal BE segment (P = 0.030) and in NSE (P = 0.001). ET-1 expression increased in a stepwise manner with the growing degree of inflammation, and there were significant differences between mild, moderate, and marked degree esophagitis (36.08 ± 27.84, 65.86 ± 11.82, 98.00 ± 8.49, P = 0.003, respectively). However, expression of receptors remained unchanged. This study demonstrates that over-expression of ET-1 and ET(A)R in esophagitis may be related to the inflammatory process. ET-1 may play a significant role in the progression of Barrett's metaplasia.

Elevated Pro-inflammatory Cytokine Levels in Acute Reflux Esophagitis Are Reduced by 1,25 Dihydroxy Vitamin D3.

BACKGROUND/AIM: Gastric acid reflux into the esophagus can cause irritation and inflammation of the esophagus and progress to reflux esophagitis (RE). Vitamin D3 (VitD3) has anti-inflammatory effects and plays an important regulatory role in adaptive and innate immunity. We hypothesized that VitD3 may play a protective role in RE. MATERIALS AND METHODS: Seventy male Sprague-Dawley rats were used, and acute RE (n=35) or chronic RE (n=35) were surgically induced. The effects of different doses of VitD3 on morphological changes and alteration of pro-inflammatory cytokine levels were examined in the rat models. Western blot analysis was performed to determine protein expression levels of IL-1ß, IL-6, and IL-8 in esophageal tissues. Serum levels of VitD3 and calcium were determined using enzyme-linked immunosorbent assays. RESULTS: The protein expression of pro-inflammatory cytokines IL-1ß, IL-6, and IL-8 was found significantly increased in RE. VitD3 treatment significantly reduced the levels of these pro-inflammatory cytokines in both the low-dose and high-dose VitD3 groups compared to control groups in acute RE, but not chronic RE. Macrographic and histopathological examination revealed various degrees of esophageal impairment in rats following surgical induction of acute or chronic RE in rats. These impairments were not improved by VitD3. Morphological grading of esophageal mucosa showed no significant differences between acute and chronic RE. Elevated serum levels of calcium were observed after VitD3 treatment. CONCLUSION: IL-1ß, IL-6, and IL-8 levels were significantly elevated in RE. The abnormal increase in these important pro-inflammatory cytokines was suppressed by VitD3 in the rat models of acute RE. These novel findings suggest a potential protective role of VitD3 in early-stage RE.

Inducible nitric oxide synthase (iNOS) and nitric oxide (NO) are important mediators of reflux-induced cell signalling in esophageal cells.

Nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) has been implicated in both DNA damage induction and aberrant cell signalling in various tissue and cell backgrounds. We investigated here the role of iNOS and NO in DNA damage induction and nuclear factor-kappa B (NF-κB) signalling in esophageal cells in vitro. As esophageal adenocarcinoma develops in a background of Barrett's esophagus secondary to reflux disease, it is possible that inflammatory mediators like NO may be important in esophageal cancer development. We show that reflux components like stomach acid and bile acids [deoxycholic acid (DCA)] can induce iNOS gene and protein expression and produce NO generation in esophageal cells, using real-time PCR, western blotting and NO sensitive fluorescent probes, respectively. This up-regulation of iNOS expression was not dependent on NF-κB activity. DCA-induced DNA damage was independent of NF-κB and only partially dependent on iNOS and NO, as measured by the micronucleus assay. These same reflux constituents also activated the oncogenic transcription factor NF-κB, as measured by transcription factor enzyme-linked immunosorbent assay and gene expression studies with NF-κB linked genes (e.g. interleukin-8). Importantly, we show here for the first time that basal levels of NF-κB activity (and possibly acid and DCA-induced NF-κB) are dependent on iNOS/NO and this may lead to a positive feedback loop whereby induced iNOS is upstream of NF-κB, hence prolonging and potentially amplifying this signalling, presumably through NO activation of NF-κB. Furthermore, we confirm increased protein levels of iNOS in esophageal adenocarcinoma and, therefore, in neoplastic development in the esophagus.