Tu1874 A Low Mucosal Integrity in a Subgroup of Healthy Subjects Increases With Proton Pump...

1Compared to the Turkish Society (p<0,05) 2Compared to primary health care (p<0,05)

Tu1873

Esophageal Epithelial Barrier Function in GERD Patients and HealthyControls: An Ex-Vivo Study in the Basal State and in Response to AcidExposureNicolaas Fedde Rinsma, Montserrat Elizalde, Freddy Troost, Ad Masclee, José M.Conchillo

Background: Esophageal epithelial integrity is considered an important factor in the preven-tion of tissue damage by gastric refluxate. We hypothesized that in patients with gastroesopha-geal reflux disease (GERD) the esophageal epithelial barrier function is impaired and lessresistant in response to acid exposure. We therefore investigated esophageal epithelial integ-rity in GERD patients and in healthy controls both in the basal state and in response toacid exposure Methods: 14 patients with chronic GERD (8 with erosive esophagitis, 6 withnon-erosive reflux disease) and 10 healthy controls (HC) were enrolled. Before endoscopy,GERD patients discontinued PPI therapy for 7 days. Six esophageal biopsies from macroscopi-cally normal mucosa were obtained approximately 5 cm above the gastroesophageal junctionand directly transferred to a mini-Ussing chamber system. After an equilibration period,baseline TEER was assessed. Half of the biopsies were then exposed at their luminal sideto an acidic solution (pH1) for 30 minutes. During exposure and after removal of the acidicsolution, changes in TEER were analyzed relative to baseline TEER. Permeation to theparacellular permeation marker fluorescein (375 DA - 1 mg/ml) was assessed in all biopsies(previous acid-exposed and non-exposed) for 120 minutes. Only subjects with at least twoadequate biopsies (one for acid exposure, one as a control) were included. Results: Esophagealepithelium of GERD patients showed lower baseline TEER (127.7±13.3 Ω vs. 174.3±17.6Ω, p=0.04) and a trend toward higher transmucosal permeation of fluorescein in the non-exposed biopsies when compared to healthy controls (serosal concentration (pmol/ml) after120 min: 48.2 (7.6-66.7) vs. 6.8 (3.6-20.2), p=0.09 and AUC: 79.8 (12.9-135.6) vs. 9.0(5.5-31.3), p=0.07). Acid exposure provoked a fall in TEER that was equal for the biopsiesof GERD patients and healthy controls (-52.1±2.5% vs. -50.0±4.4% of baseline TEER). Afterremoval of the acidic solution, TEER recovered also to a similar extent in GERD patientsand healthy controls (89.6±3.8% vs. 93.8±3.0% of baseline TEER). However, maximumTEER was reached earlier in biopsies of GERD patients (54±9 min vs. 83±6 min (HC), p=0.02) and at the end of the experiment, TEER relative to baseline was lower in biopsies ofGERD patients (73.7±5.8% vs. 89.7±3.3% (HC) of baseline TEER, p<0.05). Conclusion:The esophageal epithelial barrier function of GERD patients is impaired, reflected by lowerbaseline transepithelial electrical resistance and a trend toward higher fluorescein permeation,and seems to be less resistant in response to acid exposure ex-vivo.

Tu1874

A Low Mucosal Integrity in a Subgroup of Healthy Subjects Increases WithProton Pump Inhibitor TreatmentAns Pauwels, Frank Zerbib, Sabine Roman, Jan F. Tack, Ricard Farré

Introduction: Gastro-esophageal reflux disease (GERD) is prevalent in the Western worldand a majority of GERD patients respond well to proton pump inhibitor (PPI) therapy.However, a large proportion of patients (up to 50%), mostly non-erosive reflux disease(NERD) patients remain symptomatic while using a standard dose of PPIs. NERD patients,but also 20-40% of healthy volunteers (HV) show dilated intercellular spaces. Moreover,based on recent own data (not published), we observed reduced mucosal integrity in someasymptomatic HV. This may indicate the existence of 2 sub-populations of HV, one with alow and one with a high mucosal integrity. Acid can be one of the luminal agents responsiblefor such differences. Although PPI treatment highly reduces acid exposure, the effect of PPItreatment on the mucosal integrity in HV is unknown. We aimed to study the effect of PPIson esophageal mucosal integrity in HV evaluated with impedance baseline (IB) measurements.Methods: 24h impedance-pH tracings from HV before and after treatment with esomeprazole40 mg b.i.d for 2 weeks were retrospectively analyzed. Acid exposure, the nr of acid refluxevents and IB at 3, 5 and 15 cm above the lower esophageal sphincter (LES) every 15 minduring daytime were calculated. We discarded the first hour and every 30 min after a mealperiod. Results: We studied 25 HV (median age 54y (40-60); 14 male). PPI treatmentsuppressed the nr of acid reflux events (26(13-35) vs. 0(0-2), p<0.0001) and % of totalacid exposure time (2.1(0.85-3.7) vs. 0(0-0.05), p<0.0001). Overall, IB values were signifi-cantly higher after PPI therapy, both at 3 and 5 cm above the LES, but not at 15 cm (3 cmoff 2294(1620-2860) vs. on 2546(2136-3004), p=0.04; 5 cm off 2252(1687-2923) vs. on2437(2137-3113), p=0.03). We found a highly significant correlation between IB values at3 cm and at 5 cm above the LES (p<0.0001, r=0.91). We then split our HV into "high"(n=13) and "low" IB (n=12), based on the median value at 3 and 5 cm. Both at 3 and 5cm above the LES, we found that IB values did not differ between off and on PPI therapyin the high IB group. Nevertheless, there was a significant increase in IB values in the low

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IB group after PPI use for 2 weeks (3 cm low IB off 1620(1347-1898) vs. on 2136(1784-2503), p=0.01; 5 cm low IB off 1687(1481-1892) vs. on 2204(1641-2403), p=0.02). IBvalues did not correlate with reflux parameters and neither acid exposure nor nr of acidreflux episodes was significantly different between subjects with low and those with highIB values. Conclusion: There is a sub-group of healthy subjects with a lower mucosalintegrity in the distal esophagus that consistently increases after 2 weeks of PPI therapy.Whether these subjects have a higher chance to develop GERD over time is unknown. Therole of mucosal integrity in symptom perception needs to be further explored.

Figure: Change in impedance baseline (IB) values in healthy volunteers with high and lowIB values, before and after esomeprazole 40 mg b.i.d therapy for 2 weeks, at 3 and 5 cmabove the LES.

Tu1875

Cross-Talk Between HIF-2α and NF-κB Mediates Pro-Inflammatory CytokineExpression by Esophageal Squamous Cells Exposed to Acid and Bile Salts.Xiaofang Huo, Qiuyang Zhang, Xi Zhang, Chunhua Yu, Edaire Cheng, David H. Wang,Stuart J. Spechler, Rhonda F. Souza

Introduction: Hypoxia inducible factors (HIFs) and nuclear factor-κB (NF-κB) are transcrip-tion factors that mediate cellular responses to the hypoxic stress of inflammation. ActivatedHIFs and NF-κB also can promote inflammation, and interactions (cross-talk) between thesetranscription factors have been described in a number of cell types. In earlier studies, wefound that esophageal squamous cells exposed to acidic bile salts showed increased activityof HIF-2α and NF-κB, and increased mRNA expression of theirtarget, pro-inflammatorycytokine genes. In this study, we looked for cross-talk between HIF-2α and NF-κB activatedby acidic bile salts, and explored how cross-talk might influence expression of pro-inflamma-tory cytokines involved in reflux esophagitis. Methods: Telomerase-immortalized esophagealsquamous cells from GERD patients (NES-B10T cells) were stably infected with shRNAs toknockdown HIF-2α or p65 (a subunit of NF-κB); empty vector-containing cells served ascontrols. Cells were exposed to acidic medium (pH5.5) containing conjugated bile acids(400μm) for 30 or 60 minutes, then collected over 24 hours for analyses. We assessed: 1)mRNA levels forHIF-2α, total p65 and pro-inflammatory cytokines (IL-8, COX-2, IL-1β,ICAM-1,TNF-α) by RT-PCR, 2) cytoplasmic levels of HIF-2α and NF-κB pathway proteins(phospho- and total IKK, IκB, p65), and nuclear levels of phospho- and total p65 proteinsby Western blot, and 3) NF-κB reporter activity. Results: In control cells, acidic bile saltsincreased mRNA expression of all pro-inflammatory cytokines. In p65 knockdown cells,acidic bile salts did not increase mRNA expression of any pro-inflammatory cytokine,indicating that NF-κB is required for this induction. In HIF-2α knockdown cells, acidicbile salts increased mRNA expression of all the cytokines except for COX-2 and IL-8. Inp65 knockdown cells, there were no reductions in HIF-2α mRNA and protein levels,indicating that NF-κB does not affect HIF-2α expression. In HIF-2α knockdown cells,nuclear levels of phospho- and total p65 protein were reduced and, in contrast to controlcells, acidic bile salts did not increase NF-κB reporter activity or affect levels of phosphorylatedIKK, IκB, and p65 proteins, indicating that HIF-2α contributes to NF-κB activation. Conclu-sions: Esophageal squamous cells demonstrate considerable cross-talk between HIF-2α andNF-κB. NF-κB is required for acidic bile salts to induce IL-8, COX-2, IL-1β, ICAM-1 andTNF-α, while HIF-2α is required for induction of IL-8 and COX-2. HIF-2α also contributesto NF-κB activation. These findings elucidate molecular mechanisms whereby refluxed acidand bile can cause esophageal squamous cells to activate both NF-κB and HIF-2α, andwhereby activated HIF-2α can amplify the production of pro-inflammatory cytokines thatmediate reflux esophagitis through further activation of NF-κB.

Tu1876

Factors Associated With Non Response to Proton Pump Inhibitors in PatientsReferred for Esophageal pH-Impedance MonitoringAurélien Garros, Sabine Roman, Sophie Marjoux, Francois Mion

Introduction Non-response to proton pump inhibitors (PPI) concerns 20 to 40 % of patientstreated for gastroesophageal reflux disease (GERD). The mechanisms of non-response aremultiple (noncompliance, non-acid reflux, visceral hypersensitivity, absence of GERD). Iden-tifying predictive factors of PPI non-response might help to optimize patients' treatment.The absence of endoscopic esophagitis is a known predictive factor of PPI non-response.The aim of this study was to determine clinical factors of PPI non-response in a tertiarycenter. Patients and methods One hundred and sixty eight consecutive patients (62 men,mean age 52 years, range 18-83) referred for 24-h pH-impedance monitoring were includedbetween October 2011 and May 2013. PH-impedance monitoring was indicated to demon-strate pathological GERD in patients with typical (n = 76), atypical alone (n=55) or atypicaldominant symptoms (n=37). Patients completed a questionnaire including Rome III criteriafor functional dyspepsia (epigastric pain syndrome (EPS) and post-prandial distress syndrome(PDS)) and irritable bowel syndrome (IBS). PPI non-response was clinically defined aspersistent GERD symptoms on treatment. Using pH-impedance monitoring, pathologicalGERD was defined according to normal values on and off PPI (1, 2). Comparisons betweenPPI-responders and non-responders were performed using chi-square or Mann-Whitneytests. Results Clinical PPI response could not be determined in 16 patients (10%), 126patients (75%) were considered as PPI non-responders and 26 (15%) as responders. No

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