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

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.

[Esophageal Motility Disorders - What's New?]

Esophageal motor disorders are an important cause of dysphagia but can also be associated with retrosternal pain and heartburn as well as regurgitation. In extreme cases, patients are not able to eat appropriately and lose weight. Repetitive aspiration can occur and may cause pulmonological complications. Achalasia represents the most important and best-defined esophageal motor disorder and is characterized by insufficient relaxation of the lower esophageal sphincter in combination with typical disturbances of esophageal peristalsis. Additional defined motor disorders are distal esophageal spasm, hypercontractile esophagus, absent contractility and ineffective peristalsis. Patients with appropriate symptoms should primarily undergo esophagogastroduodenoscopy for exclusion of e.g., tumors and esophagitis. Esophageal high-resolution manometry is the reference method for diagnosis and characterization of motor disorders in non-obstructive dysphagia. An esophagogram with barium swallow may deliver complementary information or may be used if manometry is not available. Balloon dilatation and Heller myotomy are long established and more or less equally effective therapeutic options for patients with achalasia. Peroral endoscopic myotomy (POEM) enhances the therapeutic armamentarium for achalasia and hypertensive/spastic motor disorders since 2010. For hypotensive motor disorders, which may occur as a complication of e.g., rheumatological diseases or idiopathically, therapeutic options are still limited.

The molecular pathogenesis of achalasia: a paired lower esophageal sphincter muscle and serum 4D label-free proteomic study

Background

Achalasia is a primary esophageal motility disorder with potential molecular pathogenesis remaining uncertain. This study aimed to identify the differentially expressed proteins and potential pathways among achalasia subtypes and controls to further reveal the molecular pathogenesis of achalasia.

Methods

Paired lower esophageal sphincter (LES) muscle and serum samples from 24 achalasia patients were collected. We also collected 10 normal serum samples from healthy controls and 10 normal LES muscle samples from esophageal cancer patients. The 4D label-free proteomic analysis was performed to identify the potential proteins and pathways involved in achalasia.

Results

Analysis of Similarities showed distinct proteomic patterns of serum and muscle samples between achalasia patients and controls (both P < 0.05). Functional enrichment analysis suggested that these differentially expressed proteins were immunity-, infection-, inflammation-, and neurodegeneration-associated. The mfuzz analysis in LES specimens showed that proteins involved in the extracellular matrix-receptor interaction increased sequentially between the control group, type III, type II, and type I achalasia. Only 26 proteins altered in the same directions in serum and muscle samples.

Conclusions

This first 4D label-free proteomic study of achalasia indicated that there were specific protein alterations in both the serum and muscle of achalasia, involving immunity, inflammation, infection, and neurodegeneration pathways. Distinct protein clusters between types I, II, and III revealed the potential molecular pathways associated with different disease stages. Analysis of proteins changed in both muscle and serum samples highlighted the importance of further studies on LES muscle and revealed potential autoantibodies.

Glyphosate affects the neurochemical phenotype of the intramural neurons in the duodenum in the pig

BACKGROUND

Glyphosate-based herbicides have been one of the most intensively used pollutants worldwide and food products containing glyphosate are an essential component of human and animal diet. The aim of present study was to determine the effect of glyphosate intoxication on the neurochemical properties of the enteric nervous system (ENS) neurons located in the wall of the porcine duodenum.

METHODS

Fifteen sexually immature gilts divided into 3 groups were used: control-animals receiving empty gelatin capsules; G1-animals receiving a low dose of glyphosate-corresponding to the theoretical maximum daily intake (TMDI) - 0.05 mg/kg bw/day; G2-animals receiving a higher dose of glyphosate-corresponding to the acceptable daily intake (ADI)-0.5 mg/kg/day in gelatin capsules orally for 28 days. After this time, the animals were euthanized and small intestine samples were collected. Frozen sections were then subjected to the procedure of double immunofluorescent staining.

KEY RESULTS

Glyphosate supplementation led to alterations in the neurochemical code of the ENS neurons in the porcine duodenum. Generally, increased population of neurons immunoreactive to PACAP, CGRP, CART, nNOS, and a decreased number of VAChT-like immunoreactive neurons were noted.

CONCLUSIONS AND INFERENCES

It may be a first preclinical symptom of digestive tract dysfunction in the course of glyphosate intoxication and further studies are needed to assess the toxicity and risks of glyphosate to humans.

Submucosal endoscopy: the present and future

Submucosal endoscopy or third-space endoscopy utilizes the potential space between the mucosal and muscularis layers of the gastrointestinal tract to execute therapeutic interventions for various diseases. Over the last decade, endoscopic access to the submucosal space has revolutionized the field of therapeutic endoscopy. Submucosal endoscopy was originally used to perform endoscopic myotomy in patients with achalasia cardia, and its use has grown exponentially since. Currently, submucosal endoscopy is widely used to resect subepithelial tumors and to manage refractory gastroparesis and Zenker's diverticulum. While the utility of submucosal endoscopy has stood the test of time in esophageal motility disorders and subepithelial tumors, its durability remains to be established in conditions such as Zenker's diverticulum and refractory gastroparesis. Other emerging indications for submucosal endoscopy include esophageal epiphrenic diverticulum, Hirschsprung's disease, and esophageal strictures not amenable to conventional endoscopic treatment. The potential of submucosal endoscopy to provide easy and safe access to the mediastinum and peritoneal spaces may open doors to novel indications and rejuvenate the interest of endoscopists in natural orifice transluminal endoscopic surgery in the future. This review focuses on the current spectrum, recent updates, and future direction of submucosal endoscopy in the gastrointestinal tract.

"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.