Changes Of Esophageal Baseline Impedance In Patients With Gastroesophageal Reflux Disease And The Related Mechanism

Gastroesophageal reflux disease(GERD)is a series of symptoms and complications caused by reflux of stomach and duodenum contents into esophagus,and its global prevalence rate is about 9%-57.6%.There are three types of GERD,including erosive esophagitis(EE),non-erosive reflux disease(NERD),and Barrett's esophagus(BE).Proton pump inhibitors(PPIs)are the first-line drug for GERD.However,a lot of GERD patients still complain reflux although daily PPIs are given.The impairment of esophageal mucosal integrity plays an important role in the pathogenesis of both endoscopic positive and endoscopic negtive GERD patients,thus more and more attention has been paid to the study of esophageal mucosal integrity in GERD patients.In recent years,the emergence of new indicators such as mean nocturnal baseline impedance(MNBI)and post-reflux swallow-induced peristaltic wave(PSPW)index has increased the clinical value of MII-p H monitoring and has become a research hotspot at present.When no reflux or swallowing occur during MII-p H monitoring,the impedance value at this time reflects the inherent conductivity of the esophageal wall,that is,the baseline impedance(BI).MNBI represents the integrity of esophageal mucosa,PSPW index reflects the chemical clearance,and both are decreased in GERD patients.BI is obtained by measuring at 3 night time periods and the averaging yields MNBI.MNBI is usually measured on 6 impedance channels of esophagus,which reduces the damage representing the integrity of esophageal mucosa.Noncardiac chest pain(NCCP)refers to recurrent angina-like chest pain,but there is no evidence of coronary heart disease.The proportion of NCCP in patients with chest pain is 20-40%.The etiology of NCCP is complex,among which GERD is the most common reason.When the esophageal mucosal integrity is impaired in GERD patients,acid penetrates the dilated intercellular space easily and reaches the sensory nerve endings,causing the symptom of heartburn.Furthermore,visceral hypersensitivity and persistent esophageal contraction seem to be important mechanisms of heartburn symptoms in NERD patients,and mucosal integrity impairments may be the basis of them.Nonetheless,the role of esophageal mucosal impairments in the perception of chest pain in GERD patients is unclear.The integrity of esophageal mucosal barrier is regulated by tight junction(TJ)between epithelial cells.Esophageal TJ protein,represented by claudins,is responsible for the barrier and polarity of epithelial cells.The structural and functional impairment of esophageal mucosal barrier in RE patients have been widely confirmed,however,there were few studies on the relationship between esophageal TJ protein and mucosal conductivity MNBI.Heme Oxygenase-1(HO-1)has been proved to play a role in maintaining mucosal integrity in gastrointestinal tract.Previous studies on the protective mechanism of HO-1 in the esophagus and its relationship with TJ protein were limited.MNBI has been most widely studied for GERD-associated esophageal mucosal impairments.The main objectives of this study are to explore the characteristics and pathogenesis of mucosal integrity impairments represented by the changes of MNBI in different subtypes of refractory GERD,which comprise three parts.Objectives: This study aimed to compare the esophageal mucosal impairment reflected by MNBI in different subtypes of refractory GERD and investigate the mechanism of esophageal motility disorders involved in MNBI changes,in order to provide new ideas for treatments of refractory GERD.Methods: 412 patients who complained persistant reflux symptoms after 8weeks' double-dose PPI treatment received gastroendoscopy,high-resolution manometry(HREM),and multichannel intraluminal impedance-p H(MII-p H)monitoring from January 1 2019 to October 1 2020.177 patients diagnosed with GERD were included into the study group,including 94 EE patients,52 NERD patients,and 31 BE patients.According to Los Angeles grade criteria,EE patients were then classified as 54 patients with LA-A/B and 40 patients with LA-C/D.52 patients diagnosed with functional heartburn(FH)and normal manometric results were used as the control group.Distal baseline impedance was acquired at 5cm(Z5)and 3cm(Z6)above lower esophageal sphincter(LES)at three stable nocturnal10-minute time periods in a steady state,and the average values were MNBI and was compared between groups.Esophageal motility related factors,including esophageal peristaltic sequences,as well as morphological and functional parameters of esophagogastric junction(EGJ)and lower esophageal sphincter(LES),were recorded.Univariate and multivariate analysis were performed to determine the effect of these factors on MNBI values in different subtypes of refractory GERD.Results: 1.The median or mean value of MNBI at Z5 in LA-C/D?LA-A/B?NERD ? BE and FH patients were as follows: 1026.5(729.0-1685.0),1690.5(1124.3-2347.5),1155.5(972.3-2027.5),2321.0(1224.0-2985.0)?,2800.0(2419.5-3306.0)?,respectively.The median or mean value of MNBI at Z6 in LA-C/D?LA-A/B?NERD?BE and FH patients were as follows: 955.0(707.8-1628.8),1410.0(884.5-2140.0),1003.0(746.3-1726.3),2091.0(981.0-2836.0)?,2662.0(2356.0-3049.5)?.2.MNBI at Z5 and Z6 in different types of refractory GERD patients was significantly lower than that of FH patients(all P <0.05).There is no significant difference in MNBI either between NERD and LA-A/B patients or between NERD and LA-C/D patients(P >0.05).The MNBI in LA-C/D and NERD patients was significantly lower than that in BE patients(P <0.05).There was no significant difference in MNBI between LA-A/B and BE patients(P >0.05).In addition,MNBI at Z5 in LA-C/D patients was significantly lower than that in LA-A/B patients(P<0.05).3.In LA-A/B patients,univariate regression analysis suggested that ineffective esophageal motility(IEM)was a suspicious risk factor for decreased MNBI,while multivariate regression analysis suggested that IEM was an independent risk factor for decreased MNBI.4.In LA-C/D patients,univariate regression analysis suggested that IEM,absent contractility,and low EGJ contraction integral(EGJ-CI)were suspicious risk factors for decreased MNBI,while multivariate regression analysis suggested that absent contractility was an independent risk factor for decreased MNBI.5.In NERD patients,univariate regression analysis showed that type III EGJ was a suspicious risk factor for decreased MNBI,while multivariate regression analysis showed that type III EGJ was an independent risk factor for decreased MNBI.6.In BE patients,univariate regression analysis suggested that decreased LES length and residual pressure were suspicious risk factor for decreased MNBI,while multivariate regression analysis suggested that decreased LES length was an independent risk factor for decreased MNBI.Conclusions: 1.Although endoscopic manifestation differs significantly,the impaired mucosal integrity of NERD patients was as severe as that of EE patients and Type III EGJ morphology(hiatus hernias)was a risk factor.The mucosal protection and the exploration of hiatus hernias should be emphasized in PPI-refractory NERD.2.Abnormal esophageal body peristalsis and decreased LES length were risk factors for the impaired mucosal integrity of PPI-refractory EE and BE patients respectively,and thus therapy on peristaltic disorders and LES function is recommended for them.Objectives : We guessed that compared with GERD patients with n NCCP(non-NCCP),the impairment of esophageal mucosal integrity in GERD patients with NCCP might be more severe.Whether the mucosal impairment is related to esophageal motility disorder and reflux clearance,and the pathophysiological mechanism will be investigated.Methods: From January 1,2019 to October 1,2020,patients with chest pain or other reflux symptoms(?twice/week,?2 months)and no previous cardiopulmonary diseases,received upper gastrointestinal endoscopy,HREM,and MII-p H monitoring.According to the results,121 patients diagnosed with GERD and a positive correlation between symptoms and reflux were included in the study group,including 47 patients with chest pain symptoms and 74 patients with other reflux symptoms.50 patients diagnosed with FH at the same time and without chest pain were included in the control group.MNBI values measured at 15?9?7?5?3cm above LES(Z1?Z2?Z3?Z4?Z5?Z6,respectively).We compared the MNBI of 6 impedance channels in 3 groups and observe whether there is any difference in MNBI between NCCP and n NCCP groups.Linear regression models were used for the relationship between esophageal dynamic parameters and abnormal MNBI in NCCP group,including abnormal morphology and function of esophagogastric junction,the resting pressure of upper and lower esophageal sphincter,and esophageal body peristalsis.Linear regression models were also used for the effect of reflux and reflux clearance on abnormal MNBI in NCCP group,including acid exposure time,acid exposure episodes,acid clearance time,liquid reflux episodes,mixed reflux episodes,acid reflux episodes,weak acid reflux episodes,non-acid reflux episodes,bolus exposure time(BET)percentage,bolus clearance time,MNBI,and PSPW index.T test,non-parametric test and ANOVA test were used for the relationship between life exposure factors,endoscopic GERD types and abnormal MNBI in NCCP group.Results:1.Compared with FH group,all 6 MNBI values in NCCP and nNCCP groups were significantly lower(all P<0.05).Compared with n NCCP group,MNBI values at Z4 and Z5 in NCCP group were significantly lower(all P<0.05).Pearson correlation analysis suggested that there were negative correlations between Z4/Z5 and symptom scores of chest pain(Z4:r=-0.300,P=0.041;Z5:r=-0.298,P=0.042).2.Reflux related regression analysis of Z4 and Z5 in NCCP group suggested that acid exposure episodes,BET percentage and PSPW index were independent risk factors of decreased Z4(all P <0.05).MNBI decreased as acid exposure episodes(?=-5.4)and BET percentage(? =-238.1)increased and as PSPW index decreased(? =58.1).Acid exposure episodes and BET percentage were independent risk factors of decreased Z5(all P<0.05).MNBI decreased as acid reflux episodes(? =-5.9)and BET percentage(? =-232.9)increased.3.Motility related regression analysis of Z4 and Z5 in NCCP group suggested that IEM was the independent risk factor of decreased Z4(P <0.05),and MNBI decreased with the the occurrence of IEM(? =-565.7).IEM and decreased LES resting pressure were independent risk factors of Z5(all P<0.05),and MNBI decreased with the the occurrence of IEM(? =-394.6)and decreased LES resting pressure(?=-381.5).4.NCCP patients with IEM had increased BET percentage(P=0.040),decreased PSPW index(P=0.038)and similar acid exposure episodes(P=0.893)compared with those without IEM.NCCP patients with decreased LES resting pressure had more acid exposure episodes(P=0.049)than those without decreased LES resting pressure.5.Z4 and Z5 in NCCP patients with body mass index ? 28,frequent drinking and overeating was decreased(all P<0.05).Conclusions: 1.The mucosal integrity represented by MNBI of all 6 chanels in NCCP and n NCCP patients were all impaired,and the mucosal impairments in NCCP at 7 and 5cm above LES were more severe than n NCCP.The degree of esophageal impairment was directly related to the severity score of chest pain,suggesting that mucosal impairments may be the reason for chest pain.2.The increased number of acid exposure episodes,the increased BET percentage,and the decreased PSPW index,as well as IEM and decreased LES resting pressure are the independent risk factors for the impaired mucosal integrity in GERD patients with NCCP.3.IEM may weaken esophageal peristalsis and saliva buffer by impairing volume clearance and chemical clearance,increase reflux burden and then impair the mucosal integrity.Decreased LES pressure may increase acid reflux directly and then impair the mucosal integrity.thus inducing chest pain symptoms.This may be the pathophysiological mechanism of mucosal injury and chest pain in GERD patients with NCCP.4.Obesity,frequent drinking and overeating were related to esophageal mucosal impairments in GERD patients with NCCP.Objectives:This part aimed to verify whether the degree of mucosal integrity impairments represented by decreased MNBI in RE patients was consistent with the expression of TJ protein and the histological score of esophageal epithelium,and confirmed that MNBI had a good evaluation effect on mucosal impairments.It has also been verified in vitro that acidic bile salts destroied TJ protein of esophageal epithelial cells by activating NF-?B and downstream IL-1? and IL-8,and HO-1 could repair and protect TJ protein by inhibiting the expression of NF-?B.Methods: 1.patients with gurgitation and heartburn underwent upper gastrointestinal endoscopy from October 2018 to June 2019.18 patients who met the re diagnosis under endoscopy were included in the study,and 2 pieces of esophageal erosive mucosa and 1 piece of normal mucosa were clamped from each patient.Then,each patient received HREM and 24 h MII-p H monitoring,and distal MNBI(Z5 and Z6)were recorded.One piece of the two erosive mucosa was embedded in paraffin,stained with HE,and was observed under optical microscope.The other piece of erosive mucosa and one piece of normal mucosa were used for Western Blot.2.Observe the histological changes of esophageal mucosa in RE patients under microscope,including basal cell hyperplasia,papillary elongation,DIS and eosinophil infiltration in epithelium.Global score(GS)was used for the evaluation,and the relationship between MNBI and GSwas evaluated.3.TJ protein claudin-1 and occludin in RE patients was measured by Western Blot,and the relationship between MNBI and TJ protein was evaluated.4.Esophageal epithelial cells were treated with acid bile salts for 4 consecutive days,3 times a day,10 minutes each time,to establish RE cell model.5.Western Blot and ELISA were used to detect the inflammatory changes in RE cells.6.RE cells were pretreated with JSH-23 and TJ protein was measured.7.RE cells were pretreated with were treated with Copp,then NF-?B and TJ protein were measured,in order to verify the role of HO-1 and NF-?B in TJ protein expression.Results: 1.There is a negative correlation between esophageal GS and MNBI in Z5(r=-0.558,P =0.016)and Z6(r=-0.626,P =0.005).2.Western Blot showed that MNBI in Z6 of RE patients was positively correlated with claudin-1 expression(r=0.516,P = 0.028).3.IL-1? and IL-8 were significantly increased,claudin-1 and occludin were significantly decreased,while HO-1 and phosphorylated NF-?B p65 protein were significantly increased in RE cells with acie bile salts(all p<0.05).4.Claudin-1 and occludin protein increased in RE cells pretreated with NF-?B inhibitor JSH-23.5.IL-1?,IL-8 and NF-?B p-p65 were decreased,HO-1 protein were increased,and the impairment of TJ proteins was alleviated in RE cells pretreated with HO-1agonist Co PP(all p<0.05).Conclusions: 1.The distal MNBI in RE patients was significantly correlated with histological damage severity and the expression of claudin-1,therefore MNBI could represent the esophageal mucosal integrity efficiently.2.The impairment of TJ protein in esophageal epithelial cells caused by acid bile salts was likely related to the activation of inflammatory factors NF-?B,IL-1? and IL-8.HO-1 could repair TJ protein by inhibiting NF-?B pathway.