Physiology of reflux disease: role of the lower esophageal sphincter

Genetic evidence for amlodipine's protective role in gastroesophageal reflux disease: A focus on CACNB2

OBJECTIVE

This study aims to elucidate the causal relationship between genetically predicted amlodipine use and the risk of gastroesophageal reflux disease (GERD) using a bidirectional Mendelian Randomization (MR) approach and to explore the underlying genetic and molecular mechanisms through functional enrichment analysis and the construction of a competing endogenous RNA (ceRNA) network.

METHODS

Publicly available GWAS datasets from the Neale Lab consortium were used, including data on amlodipine (13,693 cases, 323,466 controls) and GERD (14,316 cases, 322,843 controls). Genome-wide significant SNPs were selected as instrumental variables and clustered by linkage disequilibrium. MR analysis was conducted using R software with all five methods. Sensitivity analyses assessed pleiotropy and heterogeneity. Drug target genes were analyzed using GO and KEGG pathways. GeneMANIA was used for network visualization, and a ceRNA network was constructed with Cytoscape. Differential gene expression analysis on GERD-related datasets from GEO validated the findings.

RESULTS

The MR analysis indicated a significant negative association between genetically predicted amlodipine use and GERD risk (IVW OR = 0.872, 95% CI = 0.812-0.937, P = 0.0002). Sensitivity analyses confirmed the robustness of these findings, showing no evidence of pleiotropy or heterogeneity. The enrichment analysis identified key biological processes and pathways involving calcium ion transport and signaling. The ceRNA network highlighted core targets such as CACNB2, which were further validated by differential expression analysis intersecting drug target genes with GERD-related gene expression changes.

CONCLUSION

This study provides robust evidence of a protective effect of amlodipine against GERD, supported by genetic and molecular analyses. The findings suggest that calcium channel blockers like amlodipine could be repurposed for GERD treatment. The identification of CACNB2 and other core targets in the ceRNA network offers novel insights into the pathophysiology of GERD and potential therapeutic targets, paving the way for personalized medicine approaches to improve patient outcomes.

Chronic REM-sleep deprivation induced laryngopharyngeal reflux in rats: A preliminary study

OBJECTIVE

The aim of this study was to investigate the relationship of chronic REM-sleep deprivation with laryngopharyngeal reflux (LPR) and its mechanism.

METHODS

Forty healthy male SD rats (body weight 250-280 g) were randomly divided into four groups. The first three ones were test group, which underwent REM-sleep deprivation with different duration of time by modified multiplatform water surface method. The last group was the control one having normal sleep. All the animals were performed Dx-pH monitoring when finishing sleep deprivation, and sacrificed to study the gastric residual rate (GRR) and small intestine peristalsis (SPR) rate by charcoal meal method.

RESULTS

At prone position, the reflux incidence in the test groups fairly increased with the duration of sleep deprivation (p<0.05). The total number of reflux episodes at prone position in the test group rats with 3 months duration of sleep deprivation was significantly increased compared with that in the control ones (p<0.05). GRR in rats experiencing sleep deficiency for different duration all reduced significantly when compared to the control group (p<0.05). GRR and SPR presented continuous decline tendency with the duration of sleep deprivation (p>0.05).

CONCLUSIONS

It is suggested that chronic sleep deficiency could cause LPR in rats, which might result from the uncoordinated digestive tract motility caused by dysfunction of central nervous system after chronic REM-sleep deprivation. Our results implied that chronic REM-sleep deprivation might be one of the causes of LPR. Addressing sleep problems might help to decrease the prevalence of LPR and enhance its treatment efficacy.

The Effect of the Intra-gastric Balloon on Gastric Emptying and the DeMeester Score

BACKGROUND AND AIMS

The mechanism of weight loss with the intra-gastric balloon (IGB) is thought to be a decrease in gastric emptying (GE); however the evidence is conflicting. Nausea, abdominal pain, and gastroesophageal reflux disease (GERD) can cause intolerance resulting in early removal. This is demoralizing for the patient and costly for the healthcare system. The ability to predict which patients will have superior weight loss and tolerance is invaluable. We sought to investigate if the IGB induced weight loss by reducing GE and the effect of the IGB on the DeMeester score.

METHODS

We retrospectively reviewed prospectively collected data for patients undergoing IGB placement at a single hospital. Manometry and pH studies were performed before and with the IGB in place. Weight was measured at baseline, at removal, and 6 months later. Adverse events leading to early removal were recorded.

RESULTS

Twenty-four patients were evaluated. There was a statistically significant decrease in GE for solids with the IGB (117.92 ± 150.23 vs 281.48 ± 206.49 min; p = 0.0048), but not for liquids (54.44 ± 17.97 vs 56.08 ± 43.96 min; p = 0.7228). The lower esophageal sphincter (LES) pressure did not change significantly with placement of the IGB (17.76 ± 7.39 vs 14.74 ± 7.24 mmHg; p = 0.09). On multivariate analysis, increase in DeMeester score was associated with total body weight loss (p = 0.0125) and change in GE (p = 0.038) independently.

CONCLUSION

The IGB delays GE for solids, but not for liquids, and increases the DeMeester score by a mechanism other than a loss of LES pressure.

Development of scores assessing the refluxogenic potential of diet of patients with laryngopharyngeal reflux

OBJECTIVE

To develop clinical tools assessing the refluxogenic potential of foods and beverages (F&B) consumed by patients with laryngopharyngeal reflux (LPR).

METHODS

European experts of the LPR Study group of the Young-Otolaryngologists of the International Federation of Oto-rhino-laryngological societies were invited to identify the components of Western European F&B that would be associated with the development of LPR. Based on the list generated by experts, four authors conducted a systematic review to identify the F&B involved in the development of esophageal sphincter and motility dysfunctions, both mechanisms involved in the development of gastroesophageal reflux disease and LPR. Regarding the F&B components and the characteristics identified as important in the development of reflux, experts developed three rational scores for the assessment of the refluxogenic potential of F&B, a dish, or the overall diet of the patient.

RESULTS

Twenty-six European experts participated to the study and identified the following components of F&B as important in the development of LPR: pH; lipid, carbohydrate, protein composition; fiber composition of vegetables; alcohol degree; caffeine/theine composition; and high osmolality of beverage. A total of 72 relevant studies have contributed to identifying the Western European F&B that are highly susceptible to be involved in the development of reflux. The F&B characteristics were considered for developing a Refluxogenic Diet Score (REDS), allowing a categorization of F&B into five categories ranging from 1 (low refluxogenic F&B) to 5 (high refluxogenic F&B). From REDS, experts developed the Refluxogenic Score of a Dish (RESDI) and the Global Refluxogenic Diet Score (GRES), which allow the assessment of the refluxogenic potential of dish and the overall diet of the LPR patient, respectively.

CONCLUSION

REDS, RESDI and GRES are proposed as objective scores for assessing the refluxogenic potential of F&B composing a dish or the overall diet of LPR patients. Future studies are needed to study the correlation between these scores and the development of LPR according to impedance-pH study.

Rates of reflux before and after laparoscopic sleeve gastrectomy for severe obesity

BACKGROUND

A current management dilemma in laparoscopic sleeve gastrectomy (LSG) patients is the development of significant gastroesophageal reflux symptoms after surgery. Treatment is typically directed towards reducing acid reflux despite the surgical removal of parietal cell mass. In contrast, laparoscopic Roux-en-Y gastric bypass (LRYGB) has been known to reduce or resolve preoperative reflux symptoms. The objective of this study was to determine the incidence of preoperative and postoperative reflux of LSG and LRYGB patients, and review reflux treatment type and response.

METHODS

A retrospective chart review was performed for patients undergoing either LSG or LRYGB between January 2010 and December 2012 as part of the Weight Wise program, Royal Alexandra Hospital, Edmonton, Canada.

RESULTS

A total of 387 cases were included in our review. We observed a significant reduction in BMI postoperatively for both LSG and LRYGB groups (p < 0.001). Between surgical groups, preoperative proton-pump inhibitor (PPI) use was not significantly different; however, at 1 month (p < 0.05) to 1-2 years (p < 0.001), there was significantly increased PPI use in patients after LSG in comparison to LRYGB. Of the LSG patients that continued their PPI treatment after surgery, 58% increased, 42% continued the same, and 0% decreased their dose 1 year after surgery.

CONCLUSIONS

Reflux symptoms are significantly increased after LSG in comparison to LRYGB patients. In addition, LSG patients more frequently require initiation of reflux treatment after surgery than that of LRYGB patients. Patients reported postoperative reflux symptom relief with acid-suppressant therapies.

High-resolution manometry for the evaluation of gastric motility

This review focus on the utility of HRM for the evaluation of gastric motility. The evaluation of gastric motility has clinical implications for the study of a myriad of diseases. Disordered motility represents a spectrum of dysfunction ranging from delayed gastric emptying to abnormally rapid gastric transit. Gastric motility may be measured by a variety of methods with different efficacy and different variables that may be obtained. High-resolution manometry was created and added to the diagnostic armamentarium. The methods and outcomes for the study of proximal motility that may be useful to assess the thoracoabdominal pressure gradient, gastric filling and accommodation are described. Also, studies on antroduodenal manometry are reviewed. High-resolution manometry allows gastric manometry without technical limitations found on conventional manometry; however, studies are still on the phase of understanding the normal findings.

Esophageal malignancy: A growing concern

Esophageal cancer is mainly found in Asia and east Africa and is one of the deadliest cancers in the world. However, it has not garnered much attention in the Western world due to its low incidence rate. An increasing amount of data indicate that esophageal cancer, particularly esophageal adenocarcinoma, has been rising by 6-fold annually and is now becoming the fastest growing cancer in the United States. This rise has been associated with the increase of the obese population, as abdominal fat puts extra pressure on the stomach and causes gastroesophageal reflux disease (GERD). Long standing GERD can induce esophagitis and metaplasia and, ultimately, leads to adenocarcinoma. Acid suppression has been the main strategy to treat GERD; however, it has not been proven to control esophageal malignancy effectively. In fact, its side effects have triggered multiple warnings from regulatory agencies. The high mortality and fast growth of esophageal cancer demand more vigorous efforts to look into its deeper mechanisms and come up with better therapeutic options.

Is there an association between hiatal hernia and ineffective esophageal motility in patients with gastroesophageal reflux disease?

INTRODUCTION

The pathophysiology of gastroesophageal reflux disease is multifactorial, where esophageal motility is one of the factors implicated in its genesis. However, there is still no consensus on the existence of an association between esophageal dysmotility and hiatal hernia in patients with gastroesophageal reflux disease. The objective of this study was to establish the prevalence of esophageal dysmotility in patients with hiatal hernia and to determine if herniation is a factor related to esophageal dysmotility in patients with gastroesophageal reflux disease.

METHODS

The study included 356 patients with a clinical diagnosis of gastroesophageal reflux disease submitted to upper digestive endoscopy and esophageal functional diagnostics. Hiatal hernia was defined endoscopically by a distance equal to or greater than 2 cm between the diaphragmatic constriction and the squamocolumnar junction and esophageal dysmotility when the esophageal manometry identified the amplitude of the peristaltic waves in the distal esophagus as <30 mmHg and/or less than 80% of effective contractions. For univariate statistical analysis, the patients were divided into two groups: with and without hiatal hernia. Poisson regression models were used to estimate crude and adjusted prevalence ratios (PR) of esophageal dysmotility according to hiatal hernia.

RESULTS

Gastroesophageal reflux disease patients with hiatal hernia had a prevalence of esophageal dysmotility equal to 14.8% and those without hiatal hernia, a prevalence of 7.7% (p = 0.041). Patients with hiatal hernia also showed a higher frequency of erosive esophagitis (47.5% versus 24.2%, p < 0.001), lower low esophageal sphincter pressure (10.4 versus 13.10; p < 0.001), and higher frequency of individuals with abnormal pH-metry values (p < 0.001). The crude PR for esophageal dysmotility, according to the presence of hiatal hernia, was 1.92 (confidence interval (CI), 1.04-3.53; p = 0.037), but this association did not persist when controlled for age, esophagitis, altered pH-metry, and altered low esophageal sphincter (adjusted PR, 1.69; CI, 0.68-4.15; p = 0.257).

CONCLUSION

Despite the prevalence of esophageal dysmotility in the hiatal hernia group being higher than that in the group without hiatal hernia, the association between these variables in individuals with gastroesophageal reflux disease disappeared when controlling for age, esophagitis, altered pH-metry, and altered low esophageal sphincter, leading us to believe that in these patients, hiatal hernia is not an independent risk factor for dysmotility.

The impact of previous fundoplication on laparoscopic gastric bypass outcomes: a case-control evaluation

BACKGROUND

Gastroesophageal reflux disease (GERD) is a common comorbid condition in morbidly obese gastric bypass candidates. Unfortunately, some patients who ultimately present for bariatric surgery have previously undergone Nissen fundoplication for GERD. Many surgeons consider previous fundoplication to be a relative contraindication to subsequent laparoscopic Roux-en-Y gastric bypass (LRYGB) due to increased technical complexity and risk. We sought to compare the perioperative and long-term outcomes of a cohort of patients who had first undergone fundoplication and ultimately chose to later pursue LRYGB for morbid obesity (revision) to matched control patients.

METHODS

Data were obtained from our prospectively maintained bariatric surgery database. Patients who underwent laparoscopic takedown of a previous fundoplication and conversion to LRYGB were compared to control patients who underwent primary LRYGB. For every revision patient, two control subjects were randomly selected from the database after matching for preoperative body mass index and year of surgery.

RESULTS

From July 2002 to April 2011, 14 patients underwent laparoscopic takedown of a previous Nissen fundoplication and then underwent LRYGB. During the same interval, 673 patients underwent LRYGB as a primary procedure for obesity from which 28 were selected as controls. There were no conversions to open laparotomy in any patient. Subjects were similar demographically. Operating time and duration of hospital stay were significantly longer in revision patients. Complications were more frequent in revisions (36% revisions vs. 7% controls, P = 0.03). Excess weight loss 1-year after surgery was excellent in both groups and did not differ (69% revision vs. 69.6% controls, P = 0.93).

CONCLUSIONS

Although associated with longer operating times, longer duration of hospital stay, and complications, LRYGB after fundoplication is feasible and safe. Long-term weight loss outcomes are similar to those seen following primary LRYGB. Previous fundoplication is not a contraindication to LRYGB.

Correlation between pathological distal esophageal acid exposure and ineffective esophageal motility

AIM

To assess the correlation between esophageal dysmotility, characterized as inefficient esophageal motility (IEM), and the presence of pathological acid reflux due to a structurally defective lower esophageal sphincter (LES), hiatus hernia. (HH), or esophagitis in patients with suspected gastroesophageal reflux disease (GERD).

METHODS

311 patients referred for GERD diagnostic procedures in a gastroesopahgeal motility laboratory were included in the study. Patients underwent an interview regarding their clinical symptoms, upper endoscopy (UE), stationary esophageal manometry, and 24-h esophageal pH-metry. The following risk factors of patients in the negative pH-metry group were compared to those in the positive pH-metry group: IEM, defective LES, HH, and esophagitis. The association between IEM and positive pH-metry results was first assessed by means of univariate analysis and later determined with multivariate logistic regression analysis.

RESULTS

Out of the total of 311 studied patients, 208 met the inclusion criteria; 88 had normal and 120 had positive pH-metry results. Univariate analysis revealed that the occurrence of IEM, defective LES, and HH was significantly greater in the positive pH-metry group. Following logistic regression analysis, the occurrence of IEM remained significantly greater in the positive pH-metry group.

CONCLUSIONS

IEM is associated with the presence of abnormal acid reflux, as assessed by 24-h esophageal pH-metry, regardless of the presence of defective LES, HH, or esophagitis.

Endoscopic injection of skeletal muscle-derived cells augments gut smooth muscle sphincter function: implications for a novel therapeutic approach

INTRODUCTION

Sphincter function is a common problem in gastroenterology and leads to disorders such as GERD and fecal incontinence.

OBJECTIVE

We hypothesized that transplantation of skeletal muscle-derived cells (MDCs) into GI sphincters may improve their function, leading to a more physiological approach to treating these disorders.

DESIGN

We performed experiments to test the potential of MDCs to survive and differentiate within the GI smooth muscle in order to gain further knowledge on the biology of skeletal muscle transplantation in GI smooth muscle sphincters as well as to test the safety and feasibility of endoscopic injection of MDCs in a large animal model.

SETTING

Animal laboratory.

INTERVENTIONS

Adult male Sprague-Dawley rats and adult male beagle dogs were used. Rat-derived and dog-derived MDCs were prepared in vitro and labeled with DiI. DiI-labeled, rat-derived MDCs (200,000/4 muL phosphate buffered saline solution) were injected bilaterally in the pyloric wall of rats, and survival, differentiation, and in vitro contractility were assessed 1 month after transplantation. Dog-derived MDCs (4.0 x 10(6) cells) were also injected into the lower esophageal sphincter of 3 beagle dogs by using a standard variceal sclerotherapy needle after baseline esophageal manometry and pH monitoring. The dogs were treated with daily cyclosporine, and 2 weeks later esophageal manometry was repeated and the esophagus was examined histologically. Differentiation of grafted cells was assessed by immunofluorescence, using specific antibodies to markers of the smooth muscle phenotype (smooth muscle actin) and of the skeletal muscle phenotype (skeletal muscle myosin).

RESULTS

In rats, grafted MDCs were visualized based on DiI fluorescence and were found to be localized within the muscle wall and in the muscularis mucosa. In vitro organ bath studies showed a significant increase in the contractile response of the pyloric sphincter to exogenous acetylcholine. In dogs, MDC injection resulted in a significant increase in baseline lower esophageal sphincter pressure. Further, in 1 dog with significant baseline acid reflux, MDC injection resulted in a reduction of acid reflux, with the fraction of time with pH <4 decreasing from 26.5% to 1.5%. Transplanted MDCs were seen adding bulk to the lower esophageal area and were well-integrated into the surrounding tissue. Immunofluorescence analysis revealed weak expression of skeletal muscle myosin in grafted MDCs and no expression of smooth muscle actin in either rats or dogs.

LIMITATIONS

Animal study.

CONCLUSION

MDCs can survive and integrate into GI smooth muscle and augment their contractile response. Thus, they may have potential for the treatment of a variety of conditions.

The association between gastroesophageal reflux disease and obesity

Nearly all epidemiologic studies have found an association between increasing body mass index (BMI) and symptoms of gastroesophageal reflux disease (GERD). Changes in gastroesophageal anatomy and physiology caused by obesity may explain the association. These include an increased prevalence of esophageal motor disorders, diminished lower esophageal sphincter (LES) pressure, the development of a hiatal hernia, and increased intragastric pressure. Central adiposity may be the most important risk for the development of reflux and related complications such as Barrett's esophagus and esophageal adenocarcinoma. Weight loss, through caloric restriction and behavioral modification, has been studied infrequently as a means of improving reflux. Bariatric surgery and its effects on a number of obesity-related disorders have been studied more extensively. Roux-en-Y gastric bypass (RYGB) has been consistently associated with improvement in the symptoms and findings of GERD. The mechanism of action through which this surgery is successful at improving GERD may be independent of weight loss and needs further examination. Current evidence suggests that laparoscopic adjusted gastric banding should be avoided in these patients as the impact on gastroesophageal reflux disease appears unfavorable.

Recent developments in esophageal motor disorders

PURPOSE OF REVIEW

Every year more insight into the pathogenesis and treatment of esophageal motor disorders is obtained. This review highlights some interesting literature published in this area during the last year.

RECENT FINDINGS

Longitudinal and circular muscle contractions act in a well coordinated fashion to allow normal peristalsis. Techniques such as intraluminal impedance, high-resolution manometry and intraluminal ultrasound provide useful additional information on esophageal function both in the normal and abnormal situation. The dynamics of the gastroesophageal junction can be studied with a newly developed probe, and the mechanism behind transient lower esophageal sphincter relaxations is still being unravelled. New manometric criteria for nutcracker esophagus have been proposed, whereas further evidence is reported supporting an association between diabetes mellitus and cardiovascular disease and esophageal dysmotility and spasm, respectively. Finally, several long-term follow-up results of surgical myotomy and pneumodilatation have been reported.

SUMMARY

Due to the perfection of esophageal measuring techniques, our knowledge of esophageal function continues to increase. The studies reviewed here provide interesting information on the pathogenesis and treatment of several esophageal motor disorders.