Reduction of interstitial cells of Cajal (ICC) associated with neuronal nitric oxide synthase (n-NOS) in patients with achalasia

Focus on Achalasia in the Omics Era

Achalasia is a rare and complex esophageal disease of unknown etiology characterized by difficulty in swallowing due to the lack of opening of the lower esophageal sphincter and the absence of esophageal peristalsis. Recent advancements in technology for analyzing DNA, RNA and biomolecules in high-throughput techniques are offering new opportunities to better understand the etiology and the pathogenetic mechanisms underlying achalasia. Through this narrative review of the scientific literature, we aim to provide a comprehensive assessment of the state-of-the-art knowledge on omics of achalasia, with particular attention to those considered relevant to the pathogenesis of the disease. The notion and importance of the multi-omics approach, its limitations and future directions are also introduced, and it is highlighted how the integration of single omics data will lead to new insights into the development of achalasia and offer clinical tools which will allow early diagnosis and better patient management.

Immunohistochemical characterization of interstitial cells and their relationship to motor neurons within the mouse esophagus

Interstitial cells of Cajal (ICC) and PDGFRα+ cells regulate smooth muscle motility in the gastrointestinal (GI) tract. However, their role(s) in esophageal motility are still unclear. The mouse esophagus has traditionally been described as almost entirely skeletal muscle in nature though ICC have been identified along its entire length. The current study evaluated the distribution of skeletal and smooth muscle within the esophagus using a mouse selectively expressing eGFP in smooth muscle cells (SMCs). The relationship of SMCs to ICC and PDGFRα+ cells was also examined. SMCs declined in density in the oral direction however SMCs represented ~ 25% of the area in the distal esophagus suggesting a likeness to the transition zone observed in humans. ANO1+ intramuscular ICC (ICC-IM) were distributed along the length of the esophagus though like SMCs, declined proximally. ICC-IM were closely associated with SMCs but were also found in regions devoid of SMCs. Intramuscular and submucosal PDGFRα+ cells were densely distributed throughout the esophagus though only intramuscular PDGFRα+ cells within the LES and distal esophagus highly expressed SK3. ICC-IM and PDGFRα+ cells were closely associated with nNOS+, VIP+, VAChT+ and TH+ neurons throughout the LES and distal esophagus. GFAP+ cells resembling intramuscular enteric glia were observed within the muscle and were closely associated with ICC-IM and PDGFRα+ cells, occupying a similar location to c. These data suggest that the mouse esophagus is more similar to the human than thought previously and thus set the foundation for future functional and molecular studies using transgenic mice.

Achalasia alters physiological networks depending on sex

Achalasia is a rare esophageal motility disorder for which the etiology is not fully understood. Evidence suggests that autoimmune inflammatory infiltrates, possibly triggered by a viral infection, may lead to a degeneration of neurons within the myenteric plexus. While the infection is eventually resolved, genetically susceptible individuals may still be at risk of developing achalasia. This study aimed to determine whether immunological and physiological networks differ between male and female patients with achalasia. This cross-sectional study included 189 preoperative achalasia patients and 500 healthy blood donor volunteers. Demographic, clinical, laboratory, immunological, and tissue biomarkers were collected. Male and female participants were evaluated separately to determine the role of sex. Correlation matrices were constructed using bivariate relationships to generate complex inferential networks. These matrices were filtered based on their statistical significance to identify the most relevant relationships between variables. Network topology and node centrality were calculated using tools available in the R programming language. Previous occurrences of chickenpox, measles, and mumps infections have been proposed as potential risk factors for achalasia, with a stronger association observed in females. Principal component analysis (PCA) identified IL-22, Th2, and regulatory B lymphocytes as key variables contributing to the disease. The physiological network topology has the potential to inform whether a localized injury or illness is likely to produce systemic consequences and the resulting clinical presentation. Here we show that immunological involvement in achalasia appears localized in men because of their highly modular physiological network. In contrast, in women the disease becomes systemic because of their robust network with a larger number of inter-cluster linkages.

Ca2+ dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract

The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.

The relationship between manometric subtype and symptom details in achalasia

BACKGROUND

Although dysphagia and chest pain are the two most common symptoms in patients with achalasia, the mechanism of evoking symptoms is still unknown. The aim of this study was to reveal the relationship between symptoms and the subtypes of achalasia defined by the Chicago classification.

METHODS

A total of 71consecutive patients with newly diagnosed achalasia were enrolled between March 2009 and December 2017. Esophageal motility was assessed by high-resolution manometry (HRM) with the Chicago classification v 3.0. and esophagograms. Their symptoms were evaluated with structured self-reported questionnaires focused on dysphagia and chest pain. Symptom profiles and radiographic findings according to the manometric subtypes were investigated.

RESULTS

Among the total 71 patients, 69 patients (97%) had dysphagia and 39 patients (54%) had chest pain. Regarding dysphagia, type II patients reported dysphagia in the throat the most, while types I and III patients mostly felt it in the epigastrium. Type II patients often felt dysphagia at the time of swallowing (41%), but this was reported in only 8.7% of Type I and 33% of Type III patients (p = 0.02). Concerning chest pain, Type I patients rarely had pain during meals (14%), but more often while sleeping (43%) and in early morning (43%), while type III patients often had pain during meals (67%). Type III patients reported that solid food caused pain more often than other types (I/II/III 0/10/33%, p = 0.09).

CONCLUSIONS

Detailed symptoms of achalasia, such as its site and timing, varied by subtypes. The status of the esophageal body might induce those differences in symptoms.

Esophageal epiphrenic diverticulum treated with laparoscopic surgery in a patient with systemic sclerosis: A rare case report

INTRODUCTION AND IMPORTANCE

Systemic sclerosis is a disease characterized by autoimmune inflammation, fibrosis of the skin and internal organs, and vasculopathy. Diverticula found in the intestines are a common feature in patients with systemic sclerosis, but esophageal epiphrenic diverticulum is extremely rare. We present a rare case of esophageal epiphrenic diverticulum treated with laparoscopic diverticulectomy and Heller myotomy in a patient with systemic sclerosis.

CASE PRESENTATION

A 73-year-old woman had been treated with prednisolone for diffuse systemic sclerosis with interstitial pneumonia. The patient had complained of chronic dysphagia and reflux symptoms. A small and asymptomatic diverticulum was first detected four years ago. Endoscopy repeated because of exacerbation of symptoms revealed an enlarged diverticulum. Therefore, the patient underwent laparoscopic diverticulectomy and Heller myotomy with partial fundoplication. Her postoperative course was uneventful, and her symptoms were relieved.

CLINICAL DISCUSSION

Although patients with systemic sclerosis commonly present with reflux esophagitis, they rarely develop achalasia-like change that leads to an esophageal diverticulum. There are several treatment options for esophageal diverticulum, including transhiatal surgery, thoracic surgery, or endoscopic treatment.

CONCLUSION

Clinicians must pay attention to patient symptoms because the worsening of dysphagia might suggest an underlying achalasia-like change or epiphrenic diverticulum in the esophagus. Surgeons should determine the treatment approach with considerations of the patient's background, the location and size of the diverticulum, and other factors.

"M1/M2" Muscularis Macrophages Are Associated with Reduction of Interstitial Cells of Cajal and Glial Cells in Achalasia

BACKGROUND AND AIMS

Several studies showed muscularis macrophages (MMφ) are associated with GI motility disorders. The purpose of this study was to preliminary explore the association between MMφ and achalasia.

METHODS

Tissue samples of the lower esophageal sphincter (LES) high-pressure zone were obtained from 27 achalasia patients and 10 controls. Immunohistochemistry for MMφ, interstitial cells of Cajal (ICC), neuronal nitric oxide synthase (nNOS), and glial cells were conducted. Histological characteristics were compared between groups, and correlation analysis was performed.

RESULTS

Fewer ICC was found in achalasia compared with controls (P = 0.018), and the level of M1 macrophages was higher than that in controls no matter in terms of the number or the proportion of M1(P = 0.026 for M1 and 0.037 for M1/MMφ). Statistical differences were found between two groups in terms of proportion of M2 and ratio of M1 to M2 (P = 0.048 for M2/ MMφ and < 0.001 for M1/M2). For the correlation analysis, significant correlations were detected between levels of nNOS, ICC, and glial cells in patients with achalasia (P = 0.026 for nNOS and ICC, 0.001 for nNOS and glial cells, 0.019 for ICC and glial cells). There were significant correlations between M2/MMφ and levels of ICC (P = 0.019), glial cells (P = 0.004), and nNOS (P = 0.135).

CONCLUSION

Patients with achalasia had a higher level of M1/M2 ratio in LES and significant correlations were found between M2/MMφ and numbers of ICC and glial cells, which suggested that MMφ were probably associated with occurrence and development of achalasia.

Automated computational analysis reveals structural changes in the enteric nervous system of nNOS deficient mice

Neuronal nitric oxide synthase (nNOS) neurons play a fundamental role in inhibitory neurotransmission, within the enteric nervous system (ENS), and in the establishment of gut motility patterns. Clinically, loss or disruption of nNOS neurons has been shown in a range of enteric neuropathies. However, the effects of nNOS loss on the composition and structure of the ENS remain poorly understood. The aim of this study was to assess the structural and transcriptional consequences of loss of nNOS neurons within the murine ENS. Expression analysis demonstrated compensatory transcriptional upregulation of pan neuronal and inhibitory neuronal subtype targets within the Nos1-/- colon, compared to control C57BL/6J mice. Conventional confocal imaging; combined with novel machine learning approaches, and automated computational analysis, revealed increased interconnectivity within the Nos1-/- ENS, compared to age-matched control mice, with increases in network density, neural projections and neuronal branching. These findings provide the first direct evidence of structural and molecular remodelling of the ENS, upon loss of nNOS signalling. Further, we demonstrate the utility of machine learning approaches, and automated computational image analysis, in revealing previously undetected; yet potentially clinically relevant, changes in ENS structure which could provide improved understanding of pathological mechanisms across a host of enteric neuropathies.

The Number of Interstitial Cells of Cajal Differs Among Different Subtypes of Achalasia and is Related to Patients' Prognosis

INTRODUCTION

Achalasia is a primary esophageal motility disorder with heterogeneous manometric subtypes and prognosis, characterized by degeneration of the esophageal myenteric plexus, and reduction in interstitial cells of Cajal (ICCs). This study aimed to explore the histopathologic characteristics of lower esophageal sphincter (LES) muscle from patients with achalasia with different subtypes and different prognosis.

METHODS

We examined specimens of LES muscle from 122 patients with achalasia who underwent peroral endoscopic myotomy and from 10 control patients who underwent esophagectomy for esophageal cancer. Hematoxylin-eosin staining was performed to assess inflammation infiltration, fibrosis, and atrophy. Specific immunohistochemical staining was performed to identify ICCs and neuronal nitric oxide synthase (nNOS).

RESULTS

The number of ICCs in patients with type I achalasia was significantly lower than that in patients with type II achalasia, followed by that in control patients (type I vs type II vs control group= 0.4 vs 1.2 vs 9.5; P < 0.001). The number of nNOS-positive cells was significantly lower in patients with achalasia than that in control patients (type I vs type II vs control group = 0.0 vs 0.0 vs 8.0; P < 0.001). Nonrecurrent group had significantly more ICCs than recurrent group (type I: nonrecurrent vs recurrent = 1.0 vs 0.1; P = 0.010; type II: nonrecurrent vs recurrent = 2.0 vs 0.4; P = 0.004).

DISCUSSION

ICCs and nNOS-positive cells reduced significantly in LES muscle of patients with achalasia. The number of ICCs differed among different achalasia subtypes and was related to patients' clinical prognosis.

Variations in the Density and Distribution of Cajal Like Cells Associated With the Pathogenesis of Ureteropelvic Junction Obstruction: A Systematic Review and Meta-Analysis

Introduction: Cajal like cells (CLCs) in the upper urinary tract have an ability to generate coordinated spontaneous action potentials and are hypothesized to help propel urine from renal pelvis into the ureter. The objective of this review was to describe the variations in the density and distribution of CLCs associated with ureteropelvic junction obstruction (UPJO). Materials and Methods: Studies comparing the density and distribution of CLCs in the human upper urinary tract in patients with UPJO and healthy controls were included in this systematic review. We searched online electronic databases; Ovid MEDLINE, Scopus, PubMed and Cochrane reviews for the studies published before October 31, 2020. A meta-analysis was conducted to compare the density of CLCs at the ureteropelvic junction (UPJ) in patients with UPJO and matched controls. Results: We included 20 and seven studies in the qualitative and quantitative synthesis, respectively. In majority (55%) CLCs were located between the muscle layers of the upper urinary tract. The CLC density in the UPJ gradually increased with aging in both healthy subjects and patients with UPJO. The pooled analysis revealed that the density of CLCs at the UPJ was significantly low in patients with UPJO compared to the controls (SMD = -3.00, 95% CI = -3.89 to -2.11, p < 0.01). Conclusions: The reduction in CLC density at the UPJ in patients with UPJO suggests a contribution from CLCs in the pathogenesis of UPJO. Since age positively correlates with CLC density, it is imperative to carefully match age when conducting case control studies comparing the CLC density and distribution. Protocol Registration Number: CRD42020219882.

Multiplex immunoassays reveal increased serum cytokines and chemokines associated with the subtypes of achalasia

BACKGROUND

Achalasia is an esophageal motility disorder with unknown etiology. Previous findings indicate that immune-mediated inflammatory process causes inhibitory neuronal degeneration. This study was designed to evaluate levels of serological cytokines and chemokines in patients with achalasia.

METHODS

We collected information from forty-seven patients with achalasia who underwent peroral endoscopic myotomy. Control samples were collected from forty-seven age- and sex-matched healthy people. The concentrations of serological cytokines and chemokines were analyzed by Luminex xMAP immunoassay. Serological and clinical data were compared between groups.

KEY RESULTS

Compared with healthy controls, achalasia patients had significantly increased concentrations of eleven cytokines and chemokines, namely, TGF-ß1 (P < .001), TGF-ß2 (P < .001), TGF-ß3 (P < .001), IL-1ra (P < .001), IL-17 (P = .005), IL-18 (P < .001), IFN-γ (P < .001), MIG (P < .001), PDGF-BB (P < .001), IP-10 (P = .003), and SCGF-B (P < .001). Gene ontology (GO) and network functional enrichment analysis revealed regulation of signaling receptor activity and receptor-ligand activity were the most related pathways of these cytokines and chemokines. Levels of twelve cytokines and chemokines were significantly increased in type III compared with I/II achalasia, namely, TGF-ß2, IL-1ra, IL-2Ra, IL-18, MIG, IFN-γ, SDF-1a, Eotaxin, PDGF-BB, IP-10, MCP-1, and TRAIL.

CONCLUSIONS AND INFERENCES

Patients with achalasia exhibited increased levels of serological cytokines and chemokines. Levels of cytokines and chemokines were significantly increased in type III than in type I/II achalasia. Cytokines and chemokines might contribute to the inflammatory development of achalasia.

Possible new endoscopic finding in patients with achalasia: "Gingko leaf sign"

BACKGROUND

The diagnosis of achalasia can occasionally be difficult because of the low prevalence of apparent endoscopic abnormal findings, such as dilation and food residue, and lack of "esophageal rosette" in some patients. We have found a new endoscopic finding "Gingko leaf sign", which consists of not being able to see the full extent of the esophageal palisade vessels and a Gingko leaf-shaped morphology of a longitudinal section of the esophagogastric junction at the end of a deep inspiration, in some achalasia patients without "esophageal rosette". The aim of the study was to investigate the prevalence of "Gingko leaf sign" in these patients.

METHODS

We retrospectively compared the prevalence of "Gingko leaf sign" between 11 achalasia patients without "esophageal rosette" and 22 age-/gender-matched healthy subjects. The diagnoses of achalasia were based on the results of high-resolution manometry. We also investigated the characteristics of the patients with "Gingko leaf sign".

RESULTS

All the patients had "Gingko leaf sign", in contrast to none of the healthy subjects (p < 0.001). Four of 11 patients did not require any therapy. Six of seven patients did not relapse after balloon dilatation, but one patient required per-oral endoscopic myotomy 8 months after balloon dilatation.

CONCLUSION

All our achalasia patients without "esophageal rosette" had "Gingko leaf sign". It is possibly a useful endoscopic finding in achalasia patients without "esophageal rosette".

Neuronal Control of Esophageal Peristalsis and Its Role in Esophageal Disease

PURPOSE OF REVIEW

Esophageal peristalsis is a highly sophisticated function that involves the coordinated contraction and relaxation of striated and smooth muscles in a cephalocaudal fashion, under the control of central and peripheral neuronal mechanisms and a number of neurotransmitters. Esophageal peristalsis is determined by the balance of the intrinsic excitatory cholinergic, inhibitory nitrergic and post-inhibitory rebound excitatory output to the esophageal musculature.

RECENT FINDINGS

Dissociation of the longitudinal and circular muscle contractions characterizes different major esophageal disorders and leads to esophageal symptoms. Provocative testing during esophageal high-resolution manometry is commonly employed to assess esophageal body peristaltic reserve and underpin clinical diagnosis. Herein, we summarize the main factors that determine esophageal peristalsis and examine their role in major and minor esophageal motility disorders and eosinophilic esophagitis.

Mast cell infiltration associated with loss of interstitial cells of Cajal and neuronal degeneration in achalasia

BACKGROUND

Achalasia is a motility disorder of unknown etiology. Previous studies supported the hypothesis that autoimmune-mediated inflammatory responses produce inhibitory neuronal degeneration. This study was designed to explore the role of mast cells in achalasia.

METHODS

We collected information from 116 patients with achalasia who underwent peroral endoscopic myotomy between December 2016 and May 2017. Lower esophageal sphincter (LES) muscle biopsy was performed in all patients with achalasia, as well as 20 control subjects. The number of mast cells, interstitial cells of Cajal (ICCs), nNOS-positive cells, and S-100-positive cells in the LES were evaluated by immunohistochemistry. Pathological and clinical data were compared between groups.

KEY RESULTS

Compared with controls, the LES of patients with achalasia had significantly fewer ICCs, nNOS-positive cells, and S-100-positive cells and a higher number of mast cells (all P < 0.001). Furthermore, the increased mast cell infiltration was significantly associated with decreased ICCs, nNOS-positive cells, and S-100-positive cells in patients with achalasia (all P < 0.05). Clinically, the number of strongly positive mast cells was highest in patients with type I achalasia and lowest in those with type III achalasia (P < 0.001). In addition, patients with a history of autoimmune disease or viral infection had greater mast cell infiltration in the LES muscle (P = 0.040).

CONCLUSIONS & INFERENCES

In patients with achalasia, mast cell infiltration in the LES muscle is increased, in association with loss of ICCs and neuronal degeneration. Mast cells may thereby play a crucial role in the development of achalasia.

INPP4B overexpression and c-KIT downregulation in human achalasia

BACKGROUND

Achalasia is a rare motility disorder characterized by myenteric neuron and interstitial cells of Cajal (ICC) abnormalities leading to deranged/absent peristalsis and lack of relaxation of the lower esophageal sphincter. The mechanisms contributing to neuronal and ICC changes in achalasia are only partially understood. Our goal was to identify novel molecular features occurring in patients with primary achalasia.

METHODS

Esophageal full-thickness biopsies from 42 (22 females; age range: 16-82 years) clinically, radiologically, and manometrically characterized patients with primary achalasia were examined and compared to those obtained from 10 subjects (controls) undergoing surgery for uncomplicated esophageal cancer (or upper stomach disorders). Tissue RNA extracted from biopsies of cases and controls was used for library preparation and sequencing. Data analysis was performed with the "edgeR" option of R-Bioconductor. Data were validated by real-time RT-PCR, western blotting and immunohistochemistry.

KEY RESULTS

Quantitative transcriptome evaluation and cluster analysis revealed 111 differentially expressed genes, with a P ≤ 10^-3 . Nine genes with a P ≤ 10^-4 were further validated. CYR61, CTGF, c-KIT, DUSP5, EGR1 were downregulated, whereas AKAP6 and INPP4B were upregulated in patients vs controls. Compared to controls, immunohistochemical analysis revealed a clear increase in INPP4B, whereas c-KIT immunolabeling resulted downregulated. As INPP4B regulates Akt pathway, we used western blot to show that phospho-Akt was significantly reduced in achalasia patients vs controls.

CONCLUSIONS & INFERENCES

The identification of altered gene expression, including INPP4B, a regulator of the Akt pathway, highlights novel signaling pathways involved in the neuronal and ICC changes underlying primary achalasia.

Esophageal motility disorders: new perspectives from high-resolution manometry and histopathology

High-resolution manometry (HRM) and peroral endoscopic myotomy (POEM) have contributed significantly to the field of esophageal motility disorders in recent years. The development of HRM has categorized various esophageal motility disorders with a focus on a diverse range of manometric anomalies. Additionally, the Chicago classification criteria is widely used for manometric diagnosis. Moreover, POEM was introduced as a minimally invasive radical therapy for achalasia and shows promise for other spastic esophageal motility disorders as well. POEM has also enabled a transluminal endoscopic approach for determining the histology of the esophageal muscle layer, which is expected to assist in elucidating the etiology of disorders associated with esophageal motility. The purpose of this review is to update the diagnosis, pathology, and treatment of esophageal motility disorders, with a focus on the recent advances in this field.

Changes in the interstitial cells of Cajal and neuronal nitric oxide synthase positive neuronal cells with aging in the esophagus of F344 rats

The aging-associated cellular and molecular changes in esophagus have not been established, yet. Thus we evaluated histological structure, interstitial cells of Cajal (ICCs), neuronal nitric oxide synthase (nNOS)-positive cells, and contractility in the esophagus of Fischer 344 rat at different ages (6-, 31-, 74-weeks, and 2-years). The lamina propria thickness and endomysial area were calculated. The immunoreactivity of c-Kit, nNOS and protein gene product (PGP) 9.5 was counted after immunohistochemistry. Expression of c-Kit, stem cell factor (SCF), nNOS and PGP 9.5 mRNA was measured by real-time PCR, and expression of c-Kit and nNOS protein was detected by Western blot. Isovolumetric contractile force measurement and electrical field stimulation (EFS) were conducted. The lamina propria thickness increased (6 week vs 2 year, P = 0.005) and the endomysial area of longitudinal muscle decreased with aging (6 week vs 2 year, P<0.001), while endomysial area of circular muscle did not significantly decrease. The proportions of NOS-immunoreactive cells and c-Kit-immunoreactive areas declined with aging (6 week vs 2 year; P<0.001 and P = 0.004, respectively), but there was no significant change of PGP 9.5-immunopositiviy. The expressions of nNOS, c-Kit and SCF mRNA also reduced with aging (6 week vs 2 year; P = 0.006, P = 0.001 and P = 0.006, respectively), while the change of PGP 9.5 mRNA expression was not significant. Western blot showed the significant decreases of nNOS and c-Kit protein expression with aging (6 week vs 2 year; P = 0.008 and P = 0.012, respectively). The EFS-induced esophageal contractions significantly decreased in 2-yr-old rat compared with 6-wk-old rats, however, L-NG-Nitroarginine methylester did not significantly increase the spontaneous and EFS-induced contractions in the 6-wk- and 2-yr-old rat esophagus. In conclusion, an increase of lamina propria thickness, a decrease of endomysial area, c-Kit, SCF and NOS expression with preserved total enteric neurons, and contractility in aged rat esophagus may explain the aging-associated esophageal dysmotility.

The Potential for Gut Organoid Derived Interstitial Cells of Cajal in Replacement Therapy

Effective digestion requires propagation of food along the entire length of the gastrointestinal tract. This process involves coordinated waves of peristalsis produced by enteric neural cell types, including different categories of interstitial cells of Cajal (ICC). Impaired food transport along the gastrointestinal tract, either too fast or too slow, causes a range of gut motility disorders that affect millions of people worldwide. Notably, loss of ICC has been shown to affect gut motility. Patients that suffer from gut motility disorders regularly experience diarrhoea and/or constipation, insomnia, anxiety, attention lapses, irritability, dizziness, and headaches that greatly affect both physical and mental health. Limited treatment options are available for these patients, due to the scarcity of human gut tissue for research and transplantation. Recent advances in stem cell technology suggest that large amounts of rudimentary, yet functional, human gut tissue can be generated in vitro for research applications. Intriguingly, these stem cell-derived gut organoids appear to contain functional ICC, although their frequency and functional properties are yet to be fully characterised. By reviewing methods of gut organoid generation, together with what is known of the molecular and functional characteristics of ICC, this article highlights short- and long-term goals that need to be overcome in order to develop ICC-based therapies for gut motility disorders.

Hydrogen sulfide synthesis enzymes reduced in lower esophageal sphincter of patients with achalasia

The etiology of achalasia remains largely unknown. Considerable evidence reveals that the lower esophageal sphincter dysfunction is due to the lack of inhibitory neurotransmitter, secondary to esophageal neuronal inflammation or loss. Recent studies suggest hydrogen sulfide may act as an inhibitory transmitter in gastrointestinal tract, but study about hydrogen sulfide in human esophagus still lack. The aim of the study was to investigate if hydrogen sulfide synthesis enzymes could be detected in human esophagus and if the synthesis of the endogenous hydrogen sulfide could be affected in achalasia patients. Tissue samples in cardia, lower esophageal sphincter, 2 cm and 4 cm above lower esophageal sphincter were obtained from achalasia patients undergoing peroral endoscopic myotomy. Control tissues in lower esophageal sphincter were obtained from esophageal carcinoma patients. Expression of cystathionine-β-synthase and cystathionine-γ-lyase in lower esophageal sphincter of achalasia patients and control were detected by immunohistochemical staining. In addition, expression of cystathionine-β-synthase and cystathionine-γ-lyase were compared among different parts of esophagus in achalasia patients. Compared with control, the expression of cystathionine-β-synthase and cystathionine-γ-lyase in lower esophageal sphincter of achalasia patients was significantly reduced (χ² = 11.429, P = 0.010). The expression of cystathionine-β-synthase and cystathionine-γ-lyase were lower in lower esophageal sphincter than that in 2 cm and 4 cm above lower esophageal sphincter, respectively (all P < 0.05). In conclusion, the expression of hydrogen sulfide synthesis enzymes, cystathionine-β-synthase and cystathionine-γ-lyase, can be detected in human esophagus and is reduced in patients with achalasia, which implicates the involvement of the two hydrogen sulfide synthesis enzymes in the pathophysiology of achalasia.

Genetics of enteric neuropathies

Abnormal development or disturbed functioning of the enteric nervous system (ENS), the intrinsic innervation of the gastrointestinal tract, is associated with the development of neuropathic gastrointestinal motility disorders. Here, we review the underlying molecular basis of these disorders and hypothesize that many of them have a common defective biological mechanism. Genetic burden and environmental components affecting this common mechanism are ultimately responsible for disease severity and symptom heterogeneity. We believe that they act together as the fulcrum in a seesaw balanced with harmful and protective factors, and are responsible for a continuum of symptoms ranging from neuronal hyperplasia to absence of neurons.

Clinical management of achalasia: current state of the art

Achalasia is a primary disorder of esophageal motility. It classically presents with dysphagia to both solids and liquids but may be accompanied by regurgitation and chest pain. The gold standard for the diagnosis of achalasia is esophageal motility testing with manometry, which often reveals aperistalsis of the esophageal body and incomplete lower esophageal sphincter relaxation. The diagnosis is aided by complimentary tests, such as esophagogastroduodenoscopy and contrast radiography. Esophagogastroduodenoscopy is indicated to rule out mimickers of the disease known as “pseudoachalasia” (eg, malignancy). Endoscopic appearance of a dilated esophagus with retained food or saliva and a puckered lower esophageal sphincter should raise suspicion for achalasia. Additionally, barium esophagography may reveal a dilated esophagus with a distal tapering giving it a “bird’s beak” appearance. Multiple therapeutic modalities aid in the management of achalasia, the decision of which depends on operative risk factors. Conventional treatments include medical therapy, botulinum toxin injection, pneumatic dilation, and Heller myotomy. The last two are defined as the most definitive treatment options. New emerging therapies include peroral endoscopic myotomy, placement of self-expanding metallic stents, and endoscopic sclerotherapy.

Reduction of hydrogen sulfide synthesis enzymes in the esophagus of patients with achalasia: effect of hydrogen sulfide in achalasia

BACKGROUND

The aim of the present study was to investigate whether the synthesis of endogenous hydrogen sulfide (H2 S) was altered in achalasia patients and to determine the effects of H2 S on esophageal motility.

METHODS

(1) Tissue samples in lower esophageal sphincter (LES) were obtained from 22 achalasia patients during peroral endoscopic myotomy. LES muscle from eight esophageal carcinoma patients was obtained as control. The expression of cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE) was detected by immunohistochemical staining. (2) Rabbit esophageal smooth muscle strips were used to measure isometric contractions. The effects of sodium hydrosulfide (NaHS) and L-cysteine on contractile activity and bethanechol-stimulated contractile activity were evaluated. The contraction of esophageal muscle strips was also measured after the inhibition of CBS and CSE by aminooxyacetic acid (AOA) and propargylglycine (PAG).

KEY RESULTS

Both CBS and CSE could be detected in biopsies from achalasia patients and controls. Compared with controls, the expression of CBS and CSE in the LES of achalasia patients was significantly reduced (p < 0.001). Both NaHS and L-cysteine concentration-dependently inhibited esophageal contractile activity (both p < 0.05). After inhibition of CBS and CSE by PAG and AOA, esophageal contractile activity increased significantly, and this effect could be restored by NaHS but not L-cysteine (p < 0.05).

CONCLUSIONS & INFERENCES

H2 S synthesis enzymes are significantly reduced in patients with achalasia compared with the controls. H2 S inhibits esophageal contractile activity concentration-dependently, and the inhibition of H2 S synthesis enzymes increases esophageal contractile activity. H2 S might be involved in the development of achalasia.

LRIG1 Regulates Ontogeny of Smooth Muscle-Derived Subsets of Interstitial Cells of Cajal in Mice

BACKGROUND & AIMS

Interstitial cells of Cajal (ICC) control intestinal smooth muscle contraction to regulate gut motility. ICC within the plane of the myenteric plexus (ICC-MY) arise from KIT-positive progenitor cells during mouse embryogenesis. However, little is known about the ontogeny of ICC associated with the deep muscular plexus (ICC-DMP) in the small intestine and ICC associated with the submucosal plexus (ICC-SMP) in the colon. Leucine-rich repeats and immunoglobulin-like domains protein 1 (LRIG1) marks intestinal epithelial stem cells, but the role of LRIG1 in nonepithelial intestinal cells has not been identified. We sought to determine the ontogeny of ICC-DMP and ICC-SMP, and whether LRIG1 has a role in their development.

METHODS

Lrig1-null mice (homozygous Lrig1-CreERT2) and wild-type mice were analyzed by immunofluorescence and transit assays. Transit was evaluated by passage of orally administered rhodamine B-conjugated dextran. Lrig1-CreERT2 mice or mice with CreERT2 under control of an inducible smooth muscle promoter (Myh11-CreERT2) were crossed with Rosa26-LSL-YFP mice for lineage tracing analysis.

RESULTS

In immunofluorescence assays, ICC-DMP and ICC-SMP were found to express LRIG1. Based on lineage tracing, ICC-DMP and ICC-SMP each arose from LRIG1-positive smooth muscle progenitors. In Lrig1-null mice, there was loss of staining for KIT in DMP and SMP regions, as well as for 2 additional ICC markers (anoctamin-1 and neurokinin 1 receptor). Lrig1-null mice had significant delays in small intestinal transit compared with control mice.

CONCLUSIONS

LRIG1 regulates the postnatal development of ICC-DMP and ICC-SMP from smooth muscle progenitors in mice. Slowed small intestinal transit observed in Lrig1-null mice may be due, at least in part, to loss of the ICC-DMP population.

Peroral endoscopic myotomy: an evolving treatment for achalasia

Peroral endoscopic myotomy (POEM) was first performed in Japan in 2008 for uncomplicated achalasia. With excellent results, it was adopted by highly skilled endoscopists around the world and the indications for POEM were expanded to include advanced sigmoid achalasia, failed surgical myotomy, patients with previous endoscopic treatments and even other spastic oesophageal motility disorders. With increased uptake and performance of POEM, variations in technique and improved management of adverse events have been developed. Now, 6 years since the first case and with >3,000 procedures performed worldwide, long-term data has shown the efficacy of POEM to be long-lasting. A growing body of literature also exists pertaining to the learning curve, application of novel technologies, extended indications and physiologic changes with POEM. Ultimately, this once experimental procedure is evolving towards becoming the preferred treatment for achalasia and other spastic oesophageal motility disorders.

Use of Clostridium botulinum toxin in gastrointestinal motility disorders in children

More than a century has elapsed since the identification of Clostridia neurotoxins as the cause of paralytic diseases. Clostridium botulinum is a heterogeneous group of Gram-positive, rod-shaped, spore-forming, obligate anaerobic bacteria that produce a potent neurotoxin. Eight different Clostridium botulinum neurotoxins have been described (A-H) and 5 of those cause disease in humans. These toxins cause paralysis by blocking the presynaptic release of acetylcholine at the neuromuscular junction. Advantage can be taken of this blockade to alleviate muscle spams due to excessive neural activity of central origin or to weaken a muscle for treatment purposes. In therapeutic applications, minute quantities of botulinum neurotoxin type A are injected directly into selected muscles. The Food and Drug Administration first approved botulinum toxin (BT) type A in 1989 for the treatment of strabismus and blepharospasm associated with dystonia in patients 12 years of age or older. Ever since, therapeutic applications of BT have expanded to other systems, including the gastrointestinal tract. Although only a single fatality has been reported to our knowledge with use of BT for gastroenterological conditions, there are significant complications ranging from minor pain, rash and allergic reactions to pneumothorax, bowel perforation and significant paralysis of tissues surrounding the injection (including vocal cord paralysis and dysphagia). This editorial describes the clinical experience and evidence for the use BT in gastrointestinal motility disorders in children.

Recent advancement of therapeutic endoscopy in the esophageal benign diseases

Over the past 30 years, the field of endoscopy has witnessed several advances. With the advent of endoscopic mucosal resection, removal of large mucosal lesions have become possible. Thereafter, endoscopic submucosal resection was refined, permitting en bloc removal of large superficial neoplasms. Such techniques have facilitated the development of antireflux mucosectomy, a promising novel treatment for gastroesophageal reflux. The introduction and use of over the scope clips has allowed for endoscopic closure of defects in the gastrointestinal tract, which were traditionally treated with surgical intervention. With the development of per-oral endoscopic myotomy (POEM), the treatment of achalasia and spastic disorders of the esophagus have been revolutionized. From the submucosal tunnelling technique developed for POEM, Per oral endoscopic tumor resection of subepithelial tumors was made possible. Simultaneously, advances in biotechnology have expanded esophageal stenting capabilities with the introduction of fully covered metal and plastic stents, as well as biodegradable stents. Once deemed a primarily diagnostic tool, endoscopy has quickly transcended to a minimally invasive intervention and therapeutic tool. These techniques are reviewed with regards to their application to benign disease of the esophagus.

Mice that express farnesylated versions of prelamin A in neurons develop achalasia

Neurons in the brain produce lamin C but almost no lamin A, a consequence of the removal of prelamin A transcripts by miR-9, a brain-specific microRNA. We have proposed that miR-9-mediated regulation of prelamin A in the brain could explain the absence of primary neurological disease in Hutchinson-Gilford progeria syndrome, a genetic disease caused by the synthesis of an internally truncated form of farnesyl-prelamin A (progerin). This explanation makes sense, but it is not entirely satisfying because it is unclear whether progerin-even if were expressed in neurons-would be capable of eliciting neuropathology. To address that issue, we created a new Lmna knock-in allele, Lmna(HG-C), which produces progerin transcripts lacking an miR-9 binding site. Mice harboring the Lmna(HG-C) allele produced progerin in neurons, but they had no pathology in the central nervous system. However, these mice invariably developed esophageal achalasia, and the enteric neurons and nerve fibers in gastrointestinal tract were markedly abnormal. The same disorder, achalasia, was observed in genetically modified mice that express full-length farnesyl-prelamin A in neurons (Zmpste24-deficient mice carrying two copies of a Lmna knock-in allele yielding full-length prelamin A transcripts lacking a miR-9 binding site). Our findings indicate that progerin and full-length farnesyl-prelamin A are toxic to neurons of the enteric nervous system.

Murine genetic deficiency of neuronal nitric oxide synthase (nNOS(-/-) ) and interstitial cells of Cajal (W/W(v) ): Implications for achalasia?

BACKGROUND AND AIM

Nitric oxide (NO) is an important inhibitory mediator of esophageal function, and its lack leads to typical features of achalasia. In contrast, the role of intramuscular interstitial cells of Cajal (ICC-IM) and vasoactive intestinal peptide (VIP) in lower esophageal sphincter (LES) function is still controversial. Therefore, we examined the function and morphology of the LES in vivo in NO-deficient (nNOS(-/-) ), ICC-IM-deficient (W/W(v) )-, and wild-type (WT) mice.

METHODS

Esophageal manometry was performed with a micro-sized transducer catheter to quantify LES pressure, swallow evoked LES relaxation, and esophageal body motility. The LES morphology was examined by semiquantitative analysis of the immunoreactivity (reduction grade I-IV) of neuronal NOS (nNOS), ICC-IM, and VIP and their correlation with esophageal function.

RESULTS

nNOS(-/-) in comparison to WT mice showed a significantly higher LES mean resting pressure with an impaired swallow induced relaxation, whereas W/W(v) mice had a hypotensive LES with decreased relaxation. W/W(v) and nNOS(-/-) mice demonstrated differing degrees of tubular esophageal dysfunction. The reduced immunoreactivity of nNOS correlated with an increased LES pressure and decreased LES relaxation, respectively. Cajal-cell reduction correlated with impaired LES relaxation, whereas VIP reduction revealed no correlation with esophageal function.

CONCLUSIONS

The reduction of ICC-IM and nNOS can cause dysfunction of the LES and esophageal peristalsis, whereas VIP reduction seems to have no effect. ICC-IM and nNOS deficiency might be independent relevant causes of esophageal dysfunction similar to that seen in human achalasia.

Bone Marrow Derived Kit-positive Cells Colonize the Gut but Fail to Restore Pacemaker Function in Intestines Lacking Interstitial Cells of Cajal

Background/Aims

Several motility disorders are associated with disruption of interstitial cells of Cajal (ICC), which provide important functions, such as pacemaker activity, mediation of neural inputs and responses to stretch in the gastrointestinal (GI) tract. Restoration of ICC networks may be therapeutic for GI motor disorders. Recent reports have suggested that Kit⁺ cells can be restored to the GI tract via bone marrow (BM) transplantation. We tested whether BM derived cells can lead to generation of functional activity in intestines naturally lacking ICC.

Methods

BM cells from Kit^+/copGFP mice, in which ICC are labeled with a green fluorescent protein, were transplanted into W/W^V intestines, lacking ICC. After 12 weeks the presence of ICC was analyzed by immunohistochemistry and functional analysis of electrical behavior and contractile properties.

Results

After 12 weeks copGFP⁺ BM derived cells were found within the myenteric region of intestines from W/W^V mice, typically populated by ICC. Kit⁺ cells failed to develop interconnections typical of ICC in the myenteric plexus. The presence of Kit⁺ cells was verified with Western analysis. BM cells failed to populate the region of the deep muscular plexus where normal ICC density, associated with the deep muscular plexus, is found in W/W^V mice. Engraftment of Kit⁺-BM cells resulted in the development of unitary potentials in transplanted muscles, but slow wave activity failed to develop. Motility analysis showed that intestinal movements in transplanted animals were abnormal and similar to untransplanted W/W^V intestines.

Conclusions

BM derived Kit⁺ cells colonized the gut after BM transplantation, however these cells failed to develop the morphology and function of mature ICC.

The muscular expression of RAS in patients with achalasia

INTRODUCTION

Angiotensin II (AngII) elicits smooth muscle contractions via activation of AngII type 1 receptor (AT1R) in the intestinal wall and in sphincter regions in several species. Achalasia is a rare swallowing disorder and is characterized by a loss of the wave-like contraction that forces food through the oesophagus and a failure of the lower oesophageal sphincter to relax during swallowing.

AIMS AND METHODS

The present study was undertaken to elucidate expression and distribution of a local renin-angiotensin system (RAS) in the muscular layer of distal normal human oesophagus as well as in patients with achalasia using western blot analysis, immunohistochemistry and polymerase chain reaction (PCR).

RESULTS

AT1R, together with enzyme renin and cathepsin D expression were decreased in patients with achalasia. In contrast, the mast cells chymase, cathepsin G, neprilysin and the receptor for angiotensin 1-7 peptides, the MAS receptor, were increased in patients with achalasia.

CONCLUSION

The results showed the existence of a local RAS in human oesophageal muscular layer. The enzymes responsible for AngII production are different and there has been a shift in receptor physiology from AT1R to MAS receptor in patients with achalasia. These changes in the RAS might play a significant role in the physiological motor control for patients with achalasia.

Peroral endoscopic myotomy for esophageal achalasia: clinical impact of 28 cases

BACKGROUND

The aim of the present study was to clarify the efficacy of peroral endoscopic myotomy (POEM) for esophageal achalasia.

PATIENTS AND METHODS

Twenty-eight esophageal achalasia patients who underwent POEM in our institution between August 2010 and October 2012 were enrolled. Under general anesthesia with tracheal intubation, initial incision was made on the anterior wall of the esophagus after submucosal injection. Submucosal tunnel was created and extended below the lower esophageal sphincter (LES) onto the gastric cardia. Subsequently, myotomy was done using triangle tip knife. After confirmation of smooth passage of scope through the esophagogastric junction, the entry was closed. Esophagogram and manometry study was done before and after the procedure. Also, subjective symptom score and Eckardt score were assessed before and 3 months after POEM.

RESULTS

POEM was successfully done in all cases without any severe complications such as perforation and mediastinitis.Mean procedure time was 99.1 min (range 61-160) and mean myotomy length was 14.4 cm (range 10-18). Significant improvement was achieved in both esophagogram and endoscopic findings. Mean LES pressure was 71.2 mmHg (35.8-119.0) and 21.0 mmHg (6.7-41.0) before and after the procedure (P < 0.05), respectively. Mean Eckardt score was 6.7 (3-12, median 7) and 0.7 (0-3, median 1) before and 3 months after POEM, respectively (P < 0.05). Symptomatic gastroesophageal reflux disease that was easily controlled by the usual dose of proton pump inhibitor was seen in six cases (21.4%) after the procedure.

CONCLUSION

POEM could be a curative standard treatment of choice for esophageal achalasia.

Alterations of the interstitial cells of Cajal and the microstructure of the gastrointestinal tract in KIT distal kinase mutant mice

The development and maintenance of interstitial cells of Cajal (ICC) are closely associated with SCF/KIT signal activity. In this study, we evaluate the distribution of ICC in KIT distal kinase domain mutant mice (Wads) and determine whether the loss-of-function mutations in KIT easily lead to gastrointestinal (GI) disorders. ICC were examined by anti-KIT immunohistochemistry and western blotting. The GI microstructure of wild-type (WT) and Wads mice in normal intestines and incomplete intestinal obstruction was evaluated by hematoxylin and eosin staining. The results in Wads(m/m) mice were as follows. Myenteric ICC were obviously decreased in the stomach and colon and were totally absent in the small intestine. Intramuscular ICC were nearly absent in the stomach and irregularly distributed in the colon. Moreover, the smooth muscle thickness of the small intestine was increased 1.3-fold in Wads(m/m), compared to WT and Wads(m/+) mice and the diameter of the intestinal lumen was also enlarged in Wads(m/m) mice. When constructing an incomplete intestinal obstruction model, the extent of distention involved was greater in Wads mice (1.6-fold in Wads(m/+) mice and 1.8-fold in Wads(m/m) mice vs. WT mice). Meanwhile, the intestinal lumen expansion and decrease in ICC were more pronounced in Wads mice than in WT mice. Our results suggest that the KIT distal kinase domain mutation leads to an ICC loss in a subtype and location-specific pattern in Wads(m/m) mice. The injury of the KIT signaling in mutant mice results in more serious pathological manifestations after being exposed to pathogenic factors.

Establishment of pacemaker activity in tissues allotransplanted with interstitial cells of Cajal

BACKGROUND

Loss or disruption of Kit(+) -interstitial cells of Cajal (ICC) capable of generating pacemaker activity has been implicated in the development of numerous gastrointestinal motility disorders. We sought to develop a model where ICC could be allotransplanted into intestines naturally devoid of these cells.

METHODS

Enzymatically dispersed cells from the intestinal tunica muscularis of Kit(+/copGFP) and Kit(V558Δ) /+ gain-of-function mice were allotransplanted into myenteric plexus regions of W/W(V) mutant intestines that lack ICC at the level of the myenteric plexus (ICC-MY) and pacemaker activity. Immunohistochemical analysis fate mapped the development of ICC-MY networks and intracellular microelectrode recordings provided evidence for the development of functional pacemaker activity.

KEY RESULTS

Kit(+) -ICC developed into distinct networks at the level of the myenteric plexus in organotypic cultures over 28 days and displayed robust rhythmic pacemaker activity.

CONCLUSIONS & INFERENCES

This study demonstrates the feasibility of allotransplantation of ICC into the myenteric region of the small intestine and the establishment of functional pacemaker activity into tissues normally devoid of ICC-MY and slow waves, thus providing a possible basis for the therapeutic treatment of patients where ICC networks have been disrupted due to a variety of pathophysiological conditions.

Partial recovery of peristalsis after myotomy for achalasia: more the rule than the exception

IMPORTANCE

Although successful treatment of achalasia depends on alleviating the obstruction at the esophagogastric junction, the postintervention contractile and pressurization pattern may also play a role in outcome.

OBJECTIVE

To determine whether myotomy that alleviates the esophagogastric junction outflow obstruction in achalasia might improve peristalsis.

DESIGN

Retrospective study from August 1, 2004, through January 30, 2012.

SETTING

Two tertiary care hospitals in Chicago and Lyon.

PATIENTS

We included 30 patients (18 male; mean age [range], 43 [17-78] years), of whom 8 had type 1 (26.6%), 17 had type 2 (56.7%), and 5 (16.7%) had type 3 achalasia according to the Chicago classification.

INTERVENTIONS

Esophageal high-resolution manometry before and after laparoscopic or endoscopic myotomy.

MAIN OUTCOMES MEASURE

The integrity of peristalsis, characterized as intact, weak contractions; frequent failed peristalsis; or premature contractions.

RESULTS

Although peristaltic fragments were evident only in patients with type 3 achalasia before treatment, intact, weak, or frequent failed peristalsis was encountered in 5 patients with type 1 (63%), 8 with type 2 (47%), and 4 with type 3 (80%) achalasia after myotomy. One patient with type 3 achalasia had distal esophageal spasm after treatment. In patients with a postmyotomy integrated relaxation pressure of less than 15 mm Hg, only 10 (40%) had persistent absent peristalsis. Panesophageal pressurization disappeared after myotomy in 16 of 19 patients. In the 5 patients with postmyotomy integrated relaxation pressure of more than 15 mm Hg, 4 had weak peristalsis and 1 had absent peristalsis.

CONCLUSIONS AND RELEVANCE

Reduction or normalization of the esophagogastric junction relaxation pressure achieved by myotomy in achalasia is associated with partial recovery of peristalsis in some patients, suggesting that the disease process progresses from the esophagogastric junction to the esophageal body. Whether the return of peristalsis is predictive of an improved therapeutic outcome requires further study.

New perspectives in the diagnosis and management of enteric neuropathies

Chronic disturbances of gastrointestinal function encompass a wide spectrum of clinical disorders that range from common conditions with mild-to-moderate symptoms to rare diseases characterized by a severe impairment of digestive function, including chronic pain, vomiting, bloating and severe constipation. Patients at the clinically severe end of the spectrum can have profound changes in gut transit and motility. In a subset of these patients, histopathological analyses have revealed abnormalities of the gut innervation, including the enteric nervous system, termed enteric neuropathies. This Review discusses advances in the diagnosis and management of the main clinical entities--achalasia, gastroparesis, intestinal pseudo-obstruction and chronic constipation--that result from enteric neuropathies, including both primary and secondary forms. We focus on the various evident neuropathologies (degenerative and inflammatory) of these disorders and, where possible, present the specific implications of histological diagnosis to contemporary treatment. This knowledge could enable the future development of novel targeted therapeutic approaches.

Neural plasticity in the gastrointestinal tract: chronic inflammation, neurotrophic signals, and hypersensitivity

Neural plasticity is not only the adaptive response of the central nervous system to learning, structural damage or sensory deprivation, but also an increasingly recognized common feature of the gastrointestinal (GI) nervous system during pathological states. Indeed, nearly all chronic GI disorders exhibit a disease-stage-dependent, structural and functional neuroplasticity. At structural level, GI neuroplasticity usually comprises local tissue hyperinnervation (neural sprouting, neural, and ganglionic hypertrophy) next to hypoinnervated areas, a switch in the neurochemical (neurotransmitter/neuropeptide) code toward preferential expression of neuropeptides which are frequently present in nociceptive neurons (e.g., substance P/SP, calcitonin-gene-related-peptide/CGRP) and of ion channels (TRPV1, TRPA1, PAR2), and concomitant activation of peripheral neural glia. The functional counterpart of these structural alterations is altered neuronal electric activity, leading to organ dysfunction (e.g., impaired motility and secretion), together with reduced sensory thresholds, resulting in hypersensitivity and pain. The present review underlines that neural plasticity in all GI organs, starting from esophagus, stomach, small and large intestine to liver, gallbladder, and pancreas, actually exhibits common phenotypes and mechanisms. Careful appraisal of these GI neuroplastic alterations reveals that--no matter which etiology, i.e., inflammatory, infectious, neoplastic/malignant, or degenerative--neural plasticity in the GI tract primarily occurs in the presence of chronic tissue- and neuro-inflammation. It seems that studying the abundant trophic and activating signals which are generated during this neuro-immune-crosstalk represents the key to understand the remarkable neuroplasticity of the GI tract.

Immunohistochemical study of the muscularis externa of the esophagus in achalasia patients

The etiology of achalasia is believed to be the neuropathy associated with chronic inflammation of the nerve plexus, but the cause of plexus inflammation is unknown. The purpose of this study was to evaluate the pathophysiology of achalasia by examining the muscularis externa of the esophagus. We used the muscularis externa of the esophagus of 62 patients with achalasia (median 44 years, male : female 32:30) who underwent surgical treatment (achalasia group) and of 10 patients (median 65.5 years, male : female 9:1) who underwent esophagectomy for thoracic esophageal cancer (control group) to perform immunohistochemical staining with S-100, CD43, c-kit (CD117), n-NOS, vasoactive intestinal polypeptide (VIP), and ubiquitin. The cell counts that were positive for S-100, n-NOS, VIP, and ubiquitin were significantly lower in the achalasia group compared with the control group (P < 0.001, P= 0.001, P < 0.001, and P= 0.001, respectively). There were no statistically significant differences with respect to CD43 and c-kit staining (P= 0.586 and P= 0.209, respectively). In conclusion, the pathophysiology of achalasia is therefore considered to be an impaired production of NO and VIP, which both affect interstitial cell of Cajal and smooth muscles, and this impairment is therefore considered to play a role in the pathophysiology of achalasia.

Etiopathological aspects of achalasia: lessons learned with Hirschsprung's disease

The etiology of primary esophageal achalasia is largely unknown. There is increasing evidence that genetic alterations might play an important but underestimated role. Current knowledge of the genetic base of Hirschsprung's disease in contrast is far more detailed. The two enteric neuropathies have several clinical features in common. This association may also exist on a cellular and molecular level. The aim of this review is to enlighten those etiopathogenetic concepts of Hirschsprung's disease that seem to be useful in uncovering the pathological processes causing achalasia. Three aspects are looked at: (i) the genetic base of Hirschsprung's disease, particularly its major susceptibility gene rearranged during transfection and its potential reference to achalasia; (ii) the altered motor functions in both conditions with loss of inhibitory innervation and interstitial cell pathology; and (iii) the involvement of these motility disorders in genetic syndromes.

Synopsis of investigations into proposed theories on the etiology of achalasia

The current state of research into the etiology of achalasia only allows for speculation. To date, several studies have been performed investigating genetic, immune, and infectious disease mechanisms; however, none of these have been conclusive. Further research into this topic is warranted given the severity of the disease, and it may be possible that all of these mechanisms are involved in the pathophysiology of the disease.

Peroral endoscopic myotomy for the treatment of achalasia: a prospective single center study

OBJECTIVES

Endoscopic balloon dilatation and laparoscopic myotomy are established treatments for achalasia. Recently, a new endoscopic technique for complete myotomy was described. Herein, we report the results of the first prospective trial of peroral endoscopic myotomy (POEM) in Europe.

METHODS

POEM was performed under general anesthesia in 16 patients (male:female (12:4), mean age 45 years, range 26-76). The primary outcome was symptom relief at 3 months, defined as an Eckhard score ≤3. Secondary outcomes were procedure-related adverse events, lower esophageal sphincter (LES) pressure on manometry, reflux symptoms, and medication use before and after POEM.

RESULTS

A 3-month follow-up was completed for all patients. Treatment success (Eckhard score ≤3) was achieved in 94% of cases (mean score pre- vs. post-treatment (8.8 vs. 1.4); P<0.001). Mean LES pressure was 27.2 mm Hg pre-treatment and 11.8 mm Hg post-treatment (P<0.001). No patient developed symptoms of gastro-esophageal reflux after treatment, but one patient was found to have an erosive lesion (LA grade A) on follow-up esophagogastroduodenoscopy. No patient required medication with proton pump inhibitors or antacids after POEM.

CONCLUSIONS

POEM is a promising new treatment for achalasia resulting in short-term symptom relief in >90% of cases. Studies evaluating long-term efficacy and comparing POEM with established treatments have been initiated.

Preliminary evidence of an association between the functional c-kit rs6554199 polymorphism and achalasia in a Turkish population

BACKGROUND

C-kit-positive interstitial cells of Cajal (ICC) of the lower esophageal sphincter are reduced in achalasia. Two functional gene polymorphisms (rs2237025 and rs6554199) within the c-kit gene may affect its transcriptional activity. In this pilot study, we hypothesized that these polymorphisms would be associated with achalasia.

METHODS

Genomic DNA was extracted and real-time PCR reactions were used to determine the rs2237025 and rs6554199 c-kit polymorphisms in 88 Turkish patients with achalasia and 101 healthy controls.

KEY RESULTS

The frequency of the T allele of rs6554199 was significantly higher in patients with achalasia [odds ratio (OR): 1.55; 95% confidence interval (CI), 1.03-2.34; P = 0.038] compared with the G allele. Under a dominant model of inheritance, the carriage of at least one T allele was significantly more frequent in patients with achalasia (80.7%) than in controls (65.3%; OR: 2.21; 95% CI, 1.13-4.33; P = 0.022). No association of the c-kit rs2237025 polymorphism with achalasia was detected.

CONCLUSIONS & INFERENCES

Despite the small sample size and the possibility of a false positive finding, our preliminary data support the hypothesis that the T allele of the c-kit rs6554199 polymorphism may be associated with achalasia in the Turkish population. These findings need to be replicated in other racial-ethnically diverse populations.

Enteric neuromuscular pathology update

The recent development of consensus guidelines for the preparation and staining of tissues, the publication of the London Classification, and reviews of what is normal in the enteric neuromusculature have been significant steps forward in this field. Increased accessibility to full-thickness biopsies of the bowel wall facilitated by advances in laparoscopic surgery have also played a part in making the decision to ask for a tissue diagnosis easier. Better antibodies for immunohistochemistry and a better understanding of disease processes at work, such as those seen in filamin mutations, all help inform the range of information that can be gleaned from what is usually a very limited sample. Clinical phenotyping remains difficult in many patients, but the availability of specialist pathologic review and the standardization of staining between laboratories are leading to better defined histologic phenotypes, that inform, in turn, possible biological processes at work in these patients. In many instances, a diagnosis may come to light only after some time, and the retention of pathologic samples in paraffin wax, as is standard practice in most laboratories, is of great value in reassessing samples, often after many years, in the light of new advances. The highest quality information, and the best answer for the patient, is, as ever, achieved by close working relationships and excellent communication between clinicians and pathologists.

Distal contraction latency: a measure of propagation velocity optimized for esophageal pressure topography studies

OBJECTIVES

A defining feature of peristalsis is propagation velocity, which determines the timing of the distal contraction relative to the swallow. This study aimed to exploit a coordinate-based strategy to quantify the normal latency of the distal esophageal contraction as a measure of propagation velocity optimized for high-resolution esophageal pressure topography (EPT) studies.

METHODS

EPT studies for 75 healthy volunteers were merged in a computer simulation. Swallows were synchronized and analyzed as a 100 × 200 pixel grid that normalized esophageal length from the pharynx to the stomach for a 20-s period to first calculate a composite for each individual and then to establish normative values for the morphology and latency of the distal contraction among individuals.

RESULTS

Stereotyped landmarks in composite EPT studies were pressure troughs in the proximal and distal esophagus isolating the distal segment and the contractile deceleration point (CDP) localizing the termination of peristalsis in the distal segment. Distal contractile latency was timed to the CDP (median 6.0 s, 95% confidence interval 4.8-7.6 s) and to lower esophageal sphincter (LES) contraction (median 9.2 s, 95% confidence interval 6.5-11.5 s). Illustrative examples are shown of rapidly conducted contractions with normal or short latency, suggesting short latency to be the preferable EPT metric of rapid propagation.

CONCLUSIONS

The proposed scheme, utilizing the topographic coordinates of contraction relative to the swallow as an alternative to conventional measures of peristaltic velocity, lays the foundation for a physiologically grounded classification of peristaltic abnormalities in EPT. Future studies will test the clinical utility of this scheme.

Pyloric resection and delayed gastric liquid emptying in rats

BACKGROUND

Surgical resection of the distal stomach impairs gastric emptying. Generally, pylorus and the antrum are removed in the distal gastrectomy, however, the pylorus is removed individually under specific circumstances. We focus on the relation between the pyloric resection and the gastric liquid emptying.

AIMS

The present investigation aimed to explore the pylorectomy how to influence gastric liquid emptying in rats.

METHODS

Pylorectomy and end-to-end gastroduodenal anastomosis were conducted in rats. Electrodes were implanted in the gastrointestinal serosal surface near the stoma. Total stomach, proximal stomach, distal stomach and duodenal liquid emptying, myoelectricities in the gastrointestinal tract near the stoma, and structures were examined with scintigraphy, electrode recording in vivo, and electron microscopy, respectively.

RESULTS

Delayed total stomach and distal stomach emptying were found in pylorectomy rats (p<0.001). However, there was no difference in the proximal stomach and the duodenal liquid emptying compared to the controls (p>0.05). The myoelectricity of 3-5 cpm (cycles/min) in antrum and 10-12 cpm in duodenum were found in the controls and no retrograde or antegrade myoelectricities were recorded in the duodenum and antrum. High-frequency myoelectricities (tachygastria) were recorded in the antrum near the stoma (p<0.01), the retrograde and antegrade myoelectricities propagating through the stoma were recorded, and the regenerated interstitial cells of Cajal were found in stoma under electron microscope observation in pylorectomy rat.

CONCLUSIONS

The gastroduodenal incoordination and abnormal myoelectricity related to impaired contraction in the antrum caused the delayed liquid gastric emptying in pylorectomy rats.