Intramuscular interstitial cells of Cajal associated with mast cells survive nitrergic nerves in achalasia

Altered Esophageal Smooth Muscle Phenotype in Achalasia

Background/Aims

Achalasia is a disorder characterized by impairment in lower esophageal sphincter relaxation and esophageal aperistalsis, caused primarily by loss of inhibitory innervation. However, little is known about associated changes in esophageal smooth muscle. We examined the contractile phenotype and innervation of the circular smooth muscle, as well as inflammatory status, and correlated these with patient-specific parameters.

Methods

Circular smooth muscle biopsies were obtained in consecutive patients with achalasia undergoing peroral endoscopic myotomy. Axonal innervation and neurotransmitter subtypes were determined with immunocytochemistry, and this was used with quantitative Polymerase Chain Reaction (qPCR) to characterize smooth muscle proliferation and cellular phenotype, as well as collagen expression. These were compared to control tissue obtained at esophagectomy and correlated with patient demographic factors including age, onset of symptoms, and Eckhardt score.

Results

Biopsies of smooth muscle were obtained from 25 patients with achalasia. Overall, there was increased mast cell number and collagen deposition but increased smooth muscle cell proliferation vs control. There was a striking drop in axon density over controls, with no differences among subtypes of achalasia. Immunocytochemical analysis showed increased expression of the contractile marker α-smooth muscle actin, principally in Type 1 achalasia, that increased with disease duration, while qPCR identified increased mRNA for smoothelin with decreased myosin heavy chain and collagen 3a1, but not collagen 1a1.

Conclusions

The thickened circular smooth muscle layer in achalasia is largely denervated, with an altered contractile phenotype and fibrosis. Biopsies obtained during peroral endoscopic myotomy provide a means to further study the pathophysiology of achalasia.

Role of mechanoregulation in mast cell-mediated immune inflammation of the smooth muscle in the pathophysiology of esophageal motility disorders

Major esophageal disorders involve obstructive transport of bolus to the stomach, causing symptoms of dysphagia and impaired clearing of the refluxed gastric contents. These may occur due to mechanical constriction of the esophageal lumen or loss of relaxation associated with deglutitive inhibition, as in achalasia-like disorders. Recently, immune inflammation has been identified as an important cause of esophageal strictures and the loss of inhibitory neurotransmission. These disorders are also associated with smooth muscle hypertrophy and hypercontractility, whose cause is unknown. This review investigated immune inflammation in the causation of smooth muscle changes in obstructive esophageal bolus transport. Findings suggest that smooth muscle hypertrophy occurs above the obstruction and is due to mechanical stress on the smooth muscles. The mechanostressed smooth muscles release cytokines and other molecules that may recruit and microlocalize mast cells to smooth muscle bundles, so that their products may have a close bidirectional effect on each other. Acting in a paracrine fashion, the inflammatory cytokines induce genetic and epigenetic changes in the smooth muscles, leading to smooth muscle hypercontractility, hypertrophy, and impaired relaxation. These changes may worsen difficulty in the esophageal transport. Immune processes differ in the first phase of obstructive bolus transport, and the second phase of muscle hypertrophy and hypercontractility. Moreover, changes in the type of mechanical stress may change immune response and effect on smooth muscles. Understanding immune signaling in causes of obstructive bolus transport, type of mechanical stress, and associated smooth muscle changes may help pathophysiology-based prevention and targeted treatment of esophageal motility disorders.NEW & NOTEWORTHY Esophageal disorders such as esophageal stricture or achalasia, and diffuse esophageal spasm are associated with smooth muscle hypertrophy and hypercontractility, above the obstruction, yet the cause of such changes is unknown. This review suggests that smooth muscle obstructive disorders may cause mechanical stress on smooth muscle, which then secretes chemicals that recruit, microlocalize, and activate mast cells to initiate immune inflammation, producing functional and structural changes in smooth muscles. Understanding the immune signaling in these changes may help pathophysiology-based prevention and targeted treatment of esophageal motility disorders.

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.

Distributions of Platelet-Derived Growth Factor Receptor-α Positive Cells and Interstitial Cells of Cajal in the Colon of Rats with Diabetes Mellitus Type 2

Background and Objectives: Diabetic gastroenteropathy (DG) is a common complication of diabetes mellitus type 2. Interstitial cells are non-neural cells of mesenchymal origin inserted between nerve elements and smooth muscle cells, necessary for normal function and peristaltic contractions in the gastrointestinal (GI) tract. There are at least two types of interstitial cells within the GI muscle layer-interstitial cells of Cajal (ICC) and interstitial platelet-derived growth factor receptor α-positive cells (IPC). The mechanism of diabetic gastroenteropathy is unclear, and interstitial cells disorders caused by metabolic changes in diabetes mellitus (DM) could explain the symptoms of DG (slow intestinal transit, constipation, fecal incontinence). The aim of this study was to identify PDGFRα and c-kit immunoreactive cells in the colon of rats with streptozotocin-nicotinamide-induced diabetes mellitus type 2, as well as to determine their distribution in relation to smooth muscle cells and enteric nerve structures. Materials and Methods: Male Wistar rats were used, and diabetes type 2 was induced by an intraperitoneal injection of streptozotocin, immediately after intraperitoneal application of nicotinamide. The colon specimens were exposed to PDGFRα and anti-c-kit antibodies to investigate interstitial cells; enteric neurons and smooth muscle cells were immunohistochemically labeled with NF-M and desmin antibodies. Results: Significant loss of the intramuscular ICC, myenteric ICC, and loss of their connection in intramuscular linear arrays and around the ganglion of the myenteric plexus were observed with no changes in nerve fiber distribution in the colon of rats with diabetes mellitus type 2. IPC were rarely present within the colon muscle layer with densely distributed PDGFRα+ cells in the colon mucosa and submucosa of both experimental groups. In summary, a decrease in intramuscular ICC, discontinuities and breakdown of contacts between myenteric ICC without changes in IPC and nerve fibers distribution were observed in the colon of streptozotocin/nicotinamide-induced diabetes type 2 rats.

RNA-sequencing reveals molecular and regional differences in the esophageal mucosa of achalasia patients

Achalasia is an esophageal motility disorder characterized by the functional loss of myenteric plexus ganglion cells in the distal esophagus and lower esophageal sphincter. Histological changes have been reported in the esophageal mucosa of achalasia, suggesting its involvement in disease pathogenesis. Despite recent advances in diagnosis, our understanding of achalasia pathogenesis at the molecular level is very limited and gene expression profiling has not been performed. We performed bulk RNA-sequencing on esophageal mucosa from 14 achalasia and 8 healthy subjects. 65 differentially expressed genes (DEGs) were found in the distal esophageal mucosa of achalasia subjects and 120 DEGs were identified in proximal esophagus. Gene expression analysis identified genes common or exclusive to proximal and distal esophagus, highlighting regional differences in the disease. Enrichment of signaling pathways related to cytokine response and viral defense were observed. Increased infiltration of CD45+ intraepithelial leukocytes were seen in the mucosa of 38 achalasia patients compared to 12 controls. Novel insights into the molecular changes occurring in achalasia were generated in this transcriptomic study. Some gene changes observed in the mucosa of achalasia may be associated with esophagitis. Differences in DEGs between distal and proximal esophagus highlight the importance of better understanding regional differences in achalasia.

"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.

Achalasia

Achalasia is a rare disorder of the oesophageal smooth muscle characterized by impaired relaxation of the lower oesophageal sphincter (LES) and absent or spastic contractions in the oesophageal body. The key pathophysiological mechanism is loss of inhibitory nerve function that probably results from an autoimmune attack targeting oesophageal myenteric nerves through cell-mediated and, possibly, antibody-mediated mechanisms. Achalasia incidence and prevalence increase with age, but the disorder can affect all ages and both sexes. Cardinal symptoms consist of dysphagia, regurgitation, chest pain and weight loss. Several years can pass between symptom onset and an achalasia diagnosis. Evaluation starts with endoscopy to rule out structural causes, followed by high-resolution manometry and/or barium radiography. Functional lumen imaging probe can provide complementary evidence. Achalasia subtypes have management and prognostic implications. Although symptom questionnaires are not useful for diagnosis, the Eckardt score is a simple symptom scoring scale that helps to quantify symptom response to therapy. Oral pharmacotherapy is not particularly effective. Botulinum toxin injection into the LES can temporize symptoms and function as a bridge to definitive therapy. Pneumatic dilation, per-oral endoscopic myotomy and laparoscopic Heller myotomy can provide durable symptom benefit. End-stage achalasia with a dilated, non-functioning oesophagus may require oesophagectomy or enteral feeding into the stomach. Long-term complications can, rarely, include oesophageal cancer, but surveillance recommendations have not been established.

Role of Macrophages and Mast Cells as Key Players in the Maintenance of Gastrointestinal Smooth Muscle Homeostasis and Disease

The gut contains the largest macrophage pool in the body, with populations of macrophages residing in the mucosa and muscularis propria of the gastrointestinal (GI) tract. Muscularis macrophages (MMs), which are located within the muscularis propria, interact with cells essential for GI function, such as interstitial cells of Cajal, enteric neurons, smooth muscle cells, enteric glia, and fibroblast-like cells, suggesting that these immune cells contribute to several aspects of GI function. This review focuses on the latest insights on the factors contributing to MM heterogeneity and the functional interaction of MMs with other cell types essential for GI function. This review integrates the latest findings on macrophages in other organs with increasing knowledge of MMs to better understand their role in a healthy and diseased gut. We describe the factors that contribute to (muscularis macrophage) MM heterogeneity, and the nature of MM interactions with cells regulating GI function. Finally, we also describe the increasing evidence suggesting a critical role of another immune cell type, the mast cell, in normal and diseased GI physiology.

Interstitial cells of Cajal and human colon motility in health and disease

Our understanding of human colonic motility, and autonomic reflexes that generate motor patterns, has increased markedly through high-resolution manometry. Details of the motor patterns are emerging related to frequency and propagation characteristics that allow linkage to interstitial cells of Cajal (ICC) networks. In studies on colonic motor dysfunction requiring surgery, ICC are almost always abnormal or significantly reduced. However, there are still gaps in our knowledge about the role of ICC in the control of colonic motility and there is little understanding of a mechanistic link between ICC abnormalities and colonic motor dysfunction. This review will outline the various ICC networks in the human colon and their proven and likely associations with the enteric and extrinsic autonomic nervous systems. Based on our extensive knowledge of the role of ICC in the control of gastrointestinal motility of animal models and the human stomach and small intestine, we propose how ICC networks are underlying the motor patterns of the human colon. The role of ICC will be reviewed in the autonomic neural reflexes that evoke essential motor patterns for transit and defecation. Mechanisms underlying ICC injury, maintenance, and repair will be discussed. Hypotheses are formulated as to how ICC dysfunction can lead to motor abnormalities in slow transit constipation, chronic idiopathic pseudo-obstruction, Hirschsprung's disease, fecal incontinence, diverticular disease, and inflammatory conditions. Recent studies on ICC repair after injury hold promise for future therapies.

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.

Diagnosis and Management of Achalasia: Updates of the Last Two Years

Achalasia is a rare neurodegenerative disorder causing dysphagia and is characterized by abnormal esophageal motor function as well as the loss of lower esophageal sphincter (LES) relaxation. The assessment and management of achalasia has significantly progressed in recent years due to the advances in high-resolution manometry (HRM) technology along with the improvements and innovations of therapeutic endoscopy procedures. The recent evolution of HRM technology with the inclusion of an adjunctive test, fluoroscopy, and EndoFLIP has enabled more precise diagnoses of achalasia to be made and the subgrouping into therapeutically meaningful subtypes. Current management possibilities include endoscopic treatments such as Botulinum toxin injected to the LES and pneumatic balloon dilation. Surgical treatment includes laparoscopic Heller myotomy and esophagectomy. Furthermore, in recent years, per oral endoscopic myotomy (POEM) has established itself as a principal endoscopic therapeutic alternative to the traditional laparoscopic Heller myotomy. The latest randomized trials report that POEM, pneumatic balloon dilatation, and laparoscopic Heller's myotomy have comparable effectiveness and complications rates. The aim of the current review is to provide a practical clinical approach to dysphagia and to shed light on the most recent improvements in diagnostics and treatment of achalasia over the last two years.

Lower esophageal sphincter muscle of patients with achalasia exhibits profound mast cell degranulation

BACKGROUND

Eosinophils and mast cells are key effectors of allergy. When they accumulate in the esophagus, their myoactive, pro-inflammatory, and cytotoxic products potentially could cause achalasia-like motility abnormalities and neuronal degeneration. We hypothesized that there is an allergy-mediated form of achalasia.

METHODS

LES muscle samples obtained during Heller myotomy from patients with achalasia or EGJ outflow obstruction (EGJOO) and from organ donor controls were immunostained for tryptase. Eosinophil and mast cell density, and mast cell degranulation were assessed. LES muscle was evaluated by qPCR for genes mediating smooth muscle Ca²⁺ handling and contraction.

KEY RESULTS

There were 13 patients (7 men, median age 59; 10 achalasia, 3 EGJOO) and 7 controls (4 men, median age 42). Eosinophils were infrequent in LES muscle, but mast cells were plentiful. Patients and controls did not differ significantly in LES mast cell density. However, 12 of 13 patients exhibited profound LES mast cell degranulation involving perimysium and myenteric plexus nerves, while only mild degranulation was seen in 2 of 7 controls. Hierarchical clustering analysis of qPCR data revealed two "mototype" LES gene expression patterns, with all type II patients in one mototype, and type I and III patients in the other.

CONCLUSIONS & INFERENCES

LES muscle of patients with achalasia or EGJOO exhibits striking mast cell degranulation, and patients with different achalasia manometric phenotypes exhibit different LES patterns of expression for genes mediating Ca²⁺ handling and muscle contraction. Although these findings are not definitive, they support our hypothesis that achalasia can be allergy-driven.

The etiology of achalasia: An immune-dominant disease

There is accumulating evidence suggesting that an autoimmune component is involved in esophageal achalasia. An increase in immune cells, cytokines, chemokines, and autoimmune antibodies in serum and infiltration of immune cells in tissues support the view that immune-mediated inflammation is a crucial pathogenesis of inhibitory neuron degeneration in the lower esophageal sphincter. Infection of viruses such as the herpes virus family has been suspected of provoking the autoimmune reaction. Meanwhile, previous reports on immunogenetics have proposed that specific risk alleles on the human leukocyte antigen complex define the susceptible population to achalasia. In this study we reviewed current knowledge regarding the immune-related factors of achalasia, including immunology, viral infection and immunogenetic variations.

Mast cell effects on esophageal smooth muscle and their potential role in eosinophilic esophagitis and achalasia

Mast cells and eosinophils are the key effector cells of allergic disorders. Although most studies on eosinophilic esophagitis (EoE), an allergic disorder of the esophagus, have focused on the role of eosinophils, recent studies suggest a major role for mast cells in causing the clinical manifestations of this disease. Cellular and animal studies have demonstrated that mast cells can cause esophageal muscle cells to proliferate and differentiate into a more contractile phenotype, and that mediators released by degranulating mast cells such as tryptase and histamine can activate smooth muscle contraction pathways. Thus, activated mast cells in the esophageal muscularis propria might cause esophageal motility abnormalities, including the failure of lower esophageal sphincter relaxation typical of achalasia. In addition, mast cells have been implicated in the pathogenesis of a number of neurodegenerative disorders of the central nervous system such as Alzheimer's and Parkinson's diseases, because degranulating mast cells release proinflammatory and cytotoxic mediators capable of damaging neurons. Such mast cell degranulation in the myenteric plexus of the esophagus could cause the loss of enteric neurons that characterizes achalasia. In this report, we review the molecular mechanisms of esophageal smooth muscle contraction, and how mast cells products might affect that muscle and cause neurodegeneration in the esophagus. Based on these data, we present our novel, conceptual model for an allergy-induced form of achalasia mediated by mast cell activation in the esophageal muscularis propria.

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.

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.

Muscle layer histopathology and manometry pattern of primary esophageal motility disorders including achalasia

BACKGROUND

Histopathology of muscularis externa in primary esophageal motility disorders has been characterized previously. We aimed to correlate the results of high-resolution manometry with those of histopathology.

METHODS

During peroral endoscopic myotomy, peroral esophageal muscle biopsy was performed in patients with primary esophageal motility disorders. Immunohistochemical staining for c-kit was performed to assess the interstitial cells of Cajal (ICCs). Hematoxylin Eosin and Azan-Mallory staining were used to detect muscle atrophy, inflammation, and fibrosis, respectively.

KEY RESULTS

Slides from 30 patients with the following motility disorders were analyzed: achalasia (type I: 14, type II: 5, type III: 3), one diffuse esophageal spasm (DES), two outflow obstruction (OO), four jackhammer esophagus (JE), and one nutcracker esophagus (NE). ICCs were preserved in high numbers in type III achalasia (n=9.4±1.2 cells/high power field [HPF]), compared to types I (n=3.7±0.3 cells/HPF) and II (n=3.5±1.0 cells/HPF). Moreover, severe fibrosis was only observed in type I achalasia and not in other types of achalasia, OO, or DES. Four of five patients with JE and NE had severe inflammation with eosinophilic infiltration of the esophageal muscle layer (73.8±50.3 eosinophils/HPF) with no epithelial eosinophils. One patient with JE showed a visceral myopathy pattern.

CONCLUSIONS & INFERENCES

Compared to types I and II, type III achalasia showed preserved ICCs, with variable data regarding DES and OO. In disorders considered as primary esophageal motility disorders, a disease category exists, which shows eosinophilic infiltration in the esophageal muscle layer with no eosinophils in the epithelium.

Reactive oxygen species and antioxidant defense in human gastrointestinal diseases

Crohn's disease and ulcerative colitis, known together as inflammatory bowel diseases (IBDs), and celiac disease are the most common disorders affecting not only adults but also children. Both IBDs and celiac disease are associated with oxidative stress, which may play a significant role in their etiologies. Reactive oxygen species (ROS) such as superoxide radicals (O2•-), hydroxyl radicals (•OH), hydrogen peroxide (H2O2), and singlet oxygen (1O2) are responsible for cell death via oxidation of DNA, proteins, lipids, and almost any other cellular constituent. To protect biological systems from free radical toxicity, several cellular antioxidant defense mechanisms exist to regulate the production of ROS, including enzymatic and nonenzymatic pathways. Superoxide dismutase catalyzes the dismutation of O2•- to H2O2 and oxygen. The glutathione redox cycle involves two enzymes: glutathione peroxidase, which uses glutathione to reduce organic peroxides and H2O2; and glutathione reductase, which reduces the oxidized form of glutathione with concomitant oxidation of nicotinamide adenine dinucleotide phosphate. In addition to this cycle, GSH can react directly with free radicals. Studies into the effects of free radicals and antioxidant status in patients with IBDs and celiac disease are scarce, especially in pediatric patients. It is therefore very necessary to conduct additional research studies to confirm previous data about ROS status and antioxidant activities in patients with IBDs and celiac disease, especially in children.

Ineffective esophageal motility and the vagus: current challenges and future prospects

Ineffective esophageal motility (IEM) is characterized by low to very low amplitude propulsive contractions in the distal esophagus, hence primarily affecting the smooth muscle part of the esophagus. IEM is often found in patients with dysphagia or heartburn and is commonly associated with gastroesophageal reflux disease. IEM is assumed to be associated with ineffective bolus transport; however, this can be verified using impedance measurements or evaluation of a barium coated marshmallow swallow. Furthermore, water swallows may not assess accurately the motor capabilities of the esophagus, since contraction amplitude is strongly determined by the size and consistency of the bolus. The “peristaltic reserve” of the esophagus can be evaluated by multiple rapid swallows that, after a period of diglutative inhibition, normally give a powerful peristaltic contraction suggestive of the integrity of neural orchestration and smooth muscle action. The amplitude of contraction is determined by a balance between intrinsic excitatory cholinergic, inhibitory nitrergic, as well as postinhibition rebound excitatory output to the musculature. This is strongly influenced by vagal efferent motor neurons and this in turn is influenced by vagal afferent neurons that send bolus information to the solitary nucleus where programmed activation of the vagal motor neurons to the smooth muscle esophagus is initiated. Solitary nucleus activity is influenced by sensory activity from a large number of organs and various areas of the brain, including the hypothalamus and the cerebral cortex. This allows interaction between swallowing activities and respiratory and cardiac activities and allows the influence of acute and chronic emotional states on swallowing behavior. Interstitial cells of Cajal are part of the sensory units of vagal afferents, the intramuscular arrays, and they provide pacemaker activity to the musculature that can generate peristalsis in the absence of innervation. This indicates that a low-amplitude esophageal contraction, observed as IEM, can be caused by a multitude of factors, and therefore many pathways can be potentially explored to restore normal esophageal peristalsis.

Berardinelli-Seip syndrome and achalasia: a shared pathomechanism?

Berardinelli-Seip congenital lipodystrophy (BSCL) is an uncommon autosomal recessive disorder. Patients with BSCL present with a distinct phenotype since subcutaneous fat is largely lacking and musculature has become more prominent. During childhood, diabetes and acanthosis nigricans evolve and female patients may develop hirsutism. Different genes encoding this entity have been described. Achalasia is a rare esophageal motility disorder, characterized by its distinct motility pattern with absent or incomplete lower esophageal sphincter (LES) relaxations. The exact cause of achalasia is yet unknown. Here, we describe a patient with achalasia in the context of BSCL, which might be linked by a shared pathophysiologic background, as evaluated in this case report.

CONCLUSION

In a BSCL patient presenting with gastrointestinal symptoms, a motility disorder of the gastrointestinal tract should be considered.

WHAT IS KNOWN

• Berardinelli-Seip congenital lipodystrophy (BSCL) and achalasia are both disorders characterized by low prevalence. What is New: • Co-existence of both diseases is described in this report. Linkage by a potential common pathophysiologic background is discussed in this paper.

Dominant role of interstitial cells of Cajal in nitrergic relaxation of murine lower oesophageal sphincter

Oesophageal achalasia is a disease known to result from reduced relaxation of the lower oesophageal sphincter (LES). Nitric oxide (NO) is one of the main inhibitory transmitters. NO-sensitive guanylyl cyclase (NO-GC) acts as the key target of NO and, by the generation of cGMP, mediates nitrergic relaxation in the LES. To date, the exact mechanism of nitrergic LES relaxation is still insufficiently elucidated. To clarify the role of NO-GC in LES relaxation, we used cell-specific knockout (KO) mouse lines for NO-GC. These include mice lacking NO-GC in smooth muscle cells (SMC-GCKO), in interstitial cells of Cajal (ICC-GCKO) and in both SMC/ICC (SMC/ICC-GCKO). We applied oesophageal manometry to study the functionality of LES in vivo. Isometric force studies were performed to monitor LES responsiveness to exogenous NO and electric field stimulation of intrinsic nerves in vitro. Cell-specific expression/deletion of NO-GC was monitored by immunohistochemistry. Swallowing-induced LES relaxation is strongly reduced by deletion of NO-GC in ICC. Basal LES tone is affected by NO-GC deletion in either SMC or ICC. Lack of NO-GC in both cells leads to a complete interruption of NO-induced relaxation and, therefore, to an achalasia-like phenotype similar to that seen in global GCKO mice. Our data indicate that regulation of basal LES tone is based on a dual mechanism mediated by NO-GC in SMC and ICC whereas swallow-induced LES relaxation is mainly regulated by nitrergic mechanisms in 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.

Megaesophagus in a line of transgenic rats: a model of achalasia

Megaesophagus is defined as the abnormal enlargement or dilatation of the esophagus, characterized by a lack of normal contraction of the esophageal walls. This is called achalasia when associated with reduced or no relaxation of the lower esophageal sphincter (LES). To date, there are few naturally occurring models for this disease. A colony of transgenic (Pvrl3-Cre) rats presented with megaesophagus at 3 to 4 months of age; further breeding studies revealed a prevalence of 90% of transgene-positive animals having megaesophagus. Affected rats could be maintained on a total liquid diet long term and were shown to display the classic features of dilated esophagus, closed lower esophageal sphincter, and abnormal contractions on contrast radiography and fluoroscopy. Histologically, the findings of muscle degeneration, inflammation, and a reduced number of myenteric ganglia in the esophagus combined with ultrastructural lesions of muscle fiber disarray and mitochondrial changes in the striated muscle of these animals closely mimic that seen in the human condition. Muscle contractile studies looking at the response of the lower esophageal sphincter and fundus to electrical field stimulation, sodium nitroprusside, and L-nitro-L-arginine methyl ester also demonstrate the similarity between megaesophagus in the transgenic rats and patients with achalasia. No primary cause for megaesophagus was found, but the close parallel to the human form of the disease, as well as ease of care and manipulation of these rats, makes this a suitable model to better understand the etiology of achalasia as well as study new management and treatment options for this incurable condition.

On the origin of rhythmic contractile activity of the esophagus in early achalasia, a clinical case study

A patient with early achalasia presented spontaneous strong rhythmic non-propulsive contractions at ~7/min, independent of swallows. Our aim was to evaluate characteristics of the rhythmic contractions, provide data on the structure of pacemaker cells in the esophagus and discuss a potential role for interstitial cells of Cajal (ICC) in the origin of rhythmicity. We hypothesize that intramuscular ICC (ICC-IM) are the primary pacemaker cells. The frequency but not the amplitude of the rhythmic contractions was inhibited by the phosphodiesterase inhibitor drotaverine consistent with cAMP inhibiting pacemaker currents in ICC-IM. The frequency increased by wet swallows but not dry swallows, consistent with stretch causing increase in slow wave frequency in ICC-IM. New studies on archival material showed that ICC-IM were present throughout the human esophageal musculature and were not diminished in early achalasia. Although ICC-IM exhibited a low density, they were connected to PDGFRα-positive fibroblast-like cells with whom they formed a dense gap junction coupled network. Nitrergic innervation of ICC was strongly diminished in early achalasia because of the loss of nitrergic nerves. It therefore appears possibly that ICC-IM function as pacemaker cells in the esophagus and that the network of ICC and PDGFRα-positive cells allows for coupling and propagation of the pacemaker activity. Loss of nitrergic innervation to ICC in achalasia may render them more excitable such that its pacemaker activity is more easily expressed. Loss of propagation in achalasia may be due to loss of contraction-induced aboral nitrergic inhibition.

Esophageal telocytes and hybrid morphologies

TCs (telocytes) are actually defined as stromal cells with specific long and thin prolongations, called Tp (telopodes). They have been positively identified in various tissues and we now report their presence in the esophagus. These cells were identified by TEM (transmission electron microscopy) in esophageal samples of Wistar rats (n = 5) occurring beneath the basal epithelial layer, in submucosa, closely related to smooth and striated muscular fibres, as also in the adventitia. They are closely related to mast cells, macrophages and microvessels. Hybrid morphologies of stromal cells processes were found: cytoplasmic processes continued distally in a telopodial fashion. Telopodes alone may not be sufficient, however, for a safe diagnosis of TCs in TEM. A larger set of specific standards (such as the telopodial emergence, and the size of the cell body and telopodes) should be considered to differentiate TCs from various species of fibroblasts. The morphological and ultrastructural features should distinguish between TCs and interstitial cells of Cajal in the digestive tract.

Interstitial Cells of Cajal: Pathology, injury and repair

Interstitial cells of cajal (ICC) are specialised cells located within the musculature of the gastrointestinal tract (GIT). Although they form only 5% of the cells in the musculature of the GIT, they play a critical role in regulating smooth muscle function and GIT motility in coordination with the enteric nervous system. C-kit is a transmembrane glycoprotein that plays a critical role in ICC development and maturation. Physiological conditions such as ageing, as well as pathological conditions that have different disease processes, negatively affect ICC networks and function. Absent or disordered ICC networks can be associated with disorders in GIT motility. This review highlights the mechanism of ICC recovery from various types of injury which entails understanding the development of ICC and the factors affecting it. ICC transformation into malignant tumours (gastrointestinal stromal tumours) and their potential as contributors to therapeutic resistance is also discussed.

Efficacy of treatment for patients with achalasia depends on the distensibility of the esophagogastric junction

BACKGROUND & AIMS

Many patients with persistent dysphagia and regurgitation after therapy have low or no lower esophageal sphincter (LES) pressure. Distensibility of the esophagogastric junction (EGJ) largely determines esophageal emptying. We investigated whether assessment of the distensibility of the EGJ is a better and more integrated parameter than LES pressure for determining efficacy of treatment for patients with achalasia.

METHODS

We measured distensibility of the EGJ using an endoscopic functional luminal imaging probe (EndoFLIP) in 15 healthy volunteers (controls; 8 male; age, 40 ± 4.1 years) and 30 patients with achalasia (16 male; age, 51 ± 3.1 years). Patients were also assessed by esophageal manometry and a timed barium esophagogram. Symptom scores were assessed using the Eckardt score, with a score <4 indicating treatment success. The effect of initial and additional treatment on distensibility and symptoms was evaluated in 7 and 5 patients, respectively.

RESULTS

EGJ distensibility was significantly reduced in untreated patients with achalasia compared with controls (0.7 ± 0.9 vs 6.3 ± 0.7 mm(2)/mm Hg; P < .001). In patients with achalasia, EGJ distensibility correlated with esophageal emptying (r = -0.72; P < .01) and symptoms (r = 0.61; P < .01) and was significantly increased with treatment. EGJ distensibility was significantly higher in patients successfully treated (Eckardt score <3) compared with those with an Eckardt score >3 (1.6 ± 0.3 vs 4.4 ± 0.5 mm(2)/mm Hg; P = .001). Even when LES pressure was low, EGJ distensibility could be reduced, which was associated with impaired emptying and recurrent symptoms.

CONCLUSIONS

EGJ distensibility is impaired in patients with achalasia and, in contrast to LES pressure, is associated with esophageal emptying and clinical response. Assessment of EGJ distensibility by EndoFLIP is a better parameter than LES pressure for evaluating efficacy of treatment for achalasia.

Immunohistochemical analysis of myenteric ganglia and interstitial cells of Cajal in ulcerative colitis

Ulcerative colitis (UC) is an inflammatory bowel disease with alterations of colonic motility, which influence clinical symptoms. Although morpho-functional abnormalities in the enteric nervous system have been suggested, in UC patients scarce attention has been paid to possible changes in the cells that control colonic motility, including myenteric neurons, glial cells and interstitial cells of Cajal (ICC). This study evaluated the neural-glial components of myenteric ganglia and ICC in the colonic neuromuscular compartment of UC patients by quantitative immunohistochemical analysis. Full-thickness archival samples of the left colon were collected from 10 patients with UC (5 males, 5 females; age range 45–62 years) who underwent elective bowel resection. The colonic neuromuscular compartment was evaluated immunohistochemically in paraffin cross-sections. The distribution and number of neurons, glial cells and ICC were assessed by anti-HuC/D, -S100β and -c-Kit antibodies, respectively. Data were compared with findings on archival samples of normal left colon from 10 sex- and age-matched control patients, who underwent surgery for uncomplicated colon cancer. Compared to controls, patients with UC showed: (i) reduced density of myenteric HuC/D⁺ neurons and S100β⁺ glial cells, with a loss over 61% and 38%, respectively, and increased glial cell/neuron ratio; (ii) ICC decrease in the whole neuromuscular compartment. The quantitative variations of myenteric neuro-glial cells and ICC indicate considerable alterations of the colonic neuromuscular compartment in the setting of mucosal inflammation associated with UC, and provide a morphological basis for better understanding the motor abnormalities often observed in UC patients.

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.

S-nitrosothiol signals in the enteric nervous system: lessons learnt from big brother

Nitric oxide (NO) is a functionally important neurotransmitter signaling molecule generated by mammalian and bacterial nitric oxide synthases (NOS), and by chemical conversion of dietary nitrite in the gastrointestinal (GI) tract. Neuronal NOS (nNOS) is the most abundant isoenzyme in the enteric nervous system, and targeted deletion in transgenic mice has clearly demonstrated its importance in normal gut function. Enteric neuropathy is also often associated with abnormal NO production, for example in achalasia and diabetic gastroparesis. Not surprisingly therefore, aberrant nNOS activity is widely implicated in enteric disease, and represents a potential molecular target for therapeutic intervention. One physiological signaling mechanism of NO bioactivity is through chemical reaction with the heme center of guanylyl cyclase, resulting in the conversion of cGMP from GTP. This second messenger nucleotide signal activates cGMP-dependent protein kinases, phosphodiesterases, and ion channels, and is implicated in the neuronal control of GI function. However, few studies in the GI tract have fully related NO bioactivity with specific molecular targets of NO-derived signals. In the central nervous system (CNS), it is now increasingly appreciated that NO bioactivity is often actively transduced via S-nitrosothiol (SNO) signals rather than via activation of guanylyl cyclase. Moreover, aberrant S-nitrosylation of specific molecular targets is implicated in CNS pathology. S-nitrosylation refers to the post-translational modification of a protein cysteine thiol by NO, forming an endogenous SNO. Because cysteine residues are often key regulators of protein function, S-nitrosylation represents a physiologically important signaling mechanism analogous to other post-translational modifications, such as O-phosphorylation. This article provides an overview of how neurotransmitter NO is produced by nNOS as this represents the most prominent and well defined source of SNO production in the enteric nervous system. Further, it provides a perspective of how S-nitrosylation signals derived from multiple diverse sources may potentially transduce NO bioactivity in the GI tract. Possible lessons that might be learnt from the CNS, such as SNO mediated auto-inhibition of nNOS activity and modulation of neuronal cell death, are also explored as these may have pathophysiological relevance in enteric neuropathy. Thus, S-nitrosylation may mediate previously underappreciated NO-derived signals in the enteric nervous system that regulate homeostatic gut functions and disease susceptibility.

Management of achalasia

Several theories on the etiology and pathophysiology of achalasia have been reported but, to date, it is widely accepted that loss of peristalsis and absence of swallow-induced relaxation of the lower esophageal sphincter are the main functional abnormalities. Treatment of achalasia often aims to alleviate the symptoms of achalasia and not to correct the underlying disorder. Medical therapy has poor efficacy, so patients who are good surgical candidates should be offered either laparoscopic myotomy or pneumatic balloon dilatation. Their own preference should be included in the decision-making process, and treatment should meet the local expertise with these procedures. Laparoscopic surgical esophagomyotomy is a safe and effective modality. It can be considered as initial management or as secondary treatment if the patient does not respond to less invasive modalities. Pneumatic dilatation has proven to be a safe, effective, and durable modality of treatment when performed by experienced individuals, and appears to be the most cost-effective alternative. For patients with multiple comorbidities and for elderly patients, who are not good surgical candidates, endoscopic injection of botulinum toxin should be considered a safe and effective procedure. However, its positive effect diminishes over time, and the need for multiple repeated sessions must be taken into consideration. In the management of patients with achalasia, nutritional aspects play an important role. When lifestyle changes are insufficient, it is necessary to proceed to percutaneous gastrostomy under radiological guidance. In the future, intraluminal myotomy or endoscopic mucosectomy will possibly be an option. Further studies are needed to investigate the role of immunosuppressive therapies in those cases in which an autoimmune etiology is suspected.

An immunohistochemical study of the myenteric plexus in idiopathic achalasia

BACKGROUND

Achalasia is a primary esophageal motor disorder characterized by degenerative changes of the myenteric plexus. The pathophysiologic abnormalities may be the final result of several intermeshing mechanisms, and more than one single factor may cause the motor abnormalities.

AIMS

To report our experience in investigating the myenteric plexus of achalasia patients undergoing esophagomyotomy.

PATIENTS AND METHODS

Tissue samples from 12 patients undergoing Heller myotomy for achalasia were evaluated and compared with esophageal tissue specimens from 7 controls. Enteric neurons and interstitial cells of Cajal (ICC) were assessed by immunohistochemical methods, and the presence of vasoactive intestinal polypeptide ergic fibers and of CD3 lymphocytes. The possible presence of herpesvirus was also assessed by immunohistochemistry, whereas that of papillomavirus was assessed by in-situ hybridization.

RESULTS

Compared with controls, achalasia patients displayed a significant decrease of both enteric neurons and ICC. Immunoreactivity for vasoactive intestinal polypeptide was completely absent in each patient. CD3 staining disclosed myenteric plexitis in 5 (42%) patients; no control patient had plexitis. All patients were completely negative for the presence of both herpes simplex virus and human papillomavirus.

CONCLUSIONS

The enteric nervous system of the lower esophageal sphincter area is impaired in patients with "idiopathic achalasia," and the abnormalities involve ICC and neurons in many patients. The triggering factors for these abnormalities are, however, still unknown.

Gastric neuromuscular pathology in gastroparesis: analysis of full-thickness antral biopsies

BACKGROUND

Pathologic assessment of gastric tissue in patients with gastroparesis is limited. Aims To evaluate gastric histopathology in patients with gastroparesis.

METHODS

Full-thickness antral biopsies were obtained in 28 patients with gastroparesis. Control specimens were obtained from patients undergoing gastric resection. H&E and immunohistochemical stained slides were reviewed for the presence of inflammation, ganglion cells, and interstitial cells of Cajal (ICCs).

RESULTS

A mild lymphocytic infiltrate in the myenteric plexus was present in 6 out of 14 patients with diabetic gastroparesis (DG), one of 14 idiopathic gastroparesis (IG) and 0 of eight controls. Significant reductions in total nerve cell bodies were seen in gastroparesis patients (2.2 +/- 0.3 per hpf; p = 0.0002) compared to controls (3.2 +/- 0.12). This was seen in both DG (2.4 +/- 0.32) and IG (2.0 +/- 0.2). Sixteen patients (ten IG and six DG) had a reduction of ganglion cells (<2.3 cells/hpf). C-kit staining showed a reduction of ICCs in six patients (five IG and one DG). Four patients (three IG and one DG) had abnormal ICC morphology on C-kit staining with more rounded morphology and less dendritic processes.

CONCLUSIONS

This study shows several pathologic abnormalities in the gastric tissue in some patients with refractory gastroparesis. An inflammatory infiltrate was present in nearly half of the patients with diabetic gastroparesis. There was a reduction in nerve cell bodies in both idiopathic and diabetic gastroparesis. A reduced number of ICCs were found in the myenteric plexus. Thus, histologic abnormalities in gastroparesis are heterogeneous and include myenteric inflammation, decreased innervation, and reduction of ICCs.

Interstitial cells of Cajal, macrophages and mast cells in the gut musculature: morphology, distribution, spatial and possible functional interactions

Interstitial cells of Cajal (ICC) are recognized as pacemaker cells for gastrointestinal movement and are suggested to be mediators of neuromuscular transmission. Intestinal motility disturbances are often associated with a reduced number of ICC and/or ultrastructural damage, sometimes associated with immune cells. Macrophages and mast cells in the intestinal muscularis externa of rodents can be found in close spatial contact with ICC. Macrophages are a constant and regularly distributed cell population in the serosa and at the level of Auerbach's plexus (AP). In human colon, ICC are in close contact with macrophages at the level of AP, suggesting functional interaction. It has therefore been proposed that ICC and macrophages interact. Macrophages and mast cells are considered to play important roles in the innate immune defence by producing pro-inflammatory mediators during classical activation, which may in itself result in damage to the tissue. They also take part in alternative activation which is associated with anti-inflammatory mediators, tissue remodelling and homeostasis, cancer, helminth infections and immunophenotype switch. ICC become damaged under various circumstances - surgical resection, possibly post-operative ileus in rodents - where innate activation takes place, and in helminth infections - where alternative activation takes place. During alternative activation the muscularis macrophage can switch phenotype resulting in up-regulation of F4/80 and the mannose receptor. In more chronic conditions such as Crohn's disease and achalasia, ICC and mast cells develop close spatial contacts and piecemeal degranulation is possibly triggered.

Altered expression of c-kit-positive cells in the ureterovesical junction after surgically created vesicoureteral reflux

PURPOSE

Peristaltic contractions propel urine unidirectionally from the renal pelvis trough the ureter and into the bladder. A morphologically and functionally competent ureterovesical junction prevents vesicoureteral reflux (VUR). According to current knowledge, pyeloureteral peristalsis is driven by atypical muscle cells within the upper urinary tract. Another likely relevant cell population, which is c-kit-positive, has been shown to be present within the whole urinary tract. Morphological changes of c-kit-positive cells have been described in VUR and pyeloureteral junction (PUJ) obstruction. Nevertheless, the functional importance of c-kit-positive interstitial cells has not yet been elucidated fully. Therefore, we investigated the influence of experimentally created VUR on the expression of c-kit-positive cells.

MATERIALS AND METHODS

We created left-sided unilateral VUR in eight Vietnamese pigs using an open surgical technique. The VUR was shown to be grade II-III by voiding cystourethrogram (VCUG), 1 and 6 months after the procedure. The animals were killed after 6 months. The vesicoureteral junction and the distal ureters were excised and fixed in 4% PFA. Paraffin sections were stained using c-kit immunohistochemistry. A quantitative evaluation was performed by two independent investigators. The unaffected, contralateral, nonrefluxing ureters served as controls.

RESULTS

We identified two types of c-kit-immunoreactive cells within the ureterovesical junction and distal ureter. The first group was comprised of round-shaped cells with substantial intracellular granulas, which resembled mast cells. Mast cells were found in the subepithelial region as well as between the muscle bundles. The number of mast cells was slightly increased in the VUR group. The second group consisted of spindle-shaped, bipolar ICC-like cells, which were seen mainly in the submucosal and muscular layers. The number of spindle-shaped c-kit-immunoreactive cells was markedly decreased in the refluxing ureter compared to the controls.

CONCLUSIONS

Surgically created VUR leads to altered expression of c-kit-positive cells. The altered distribution of c-kit-positive ICC-like cells might further contribute to the impairment of coordinated pyeloureteral peristalsis.

Loss of enteric neurons accompanied by decreased expression of GDNF and PI3K/Akt pathway in diabetic rats

To investigate the enteric neuropathy in diabetic rats and the role of glia cell line-derived neurotrophic factor (GDNF) and its signalling pathway PI3K/Akt in regulating enteric neurons survival. Male Sprague-Dawley (SD) rats were randomly divided into normal control group, diabetic groups (rats with diabetes for 4, 8 and 12 weeks respectively). Proximal and distal colon specimens were obtained from each rat. Phosphoinositol-3-kinase signalling pathway was analysed by Akt phosphorylation. Protein gene product 9.5 (PGP9.5) used as a pan-neuronal marker. The expressions of GDNF, phospho-Akt (p-Akt), neuronal nitric oxide synthase (nNOS) neurons, cholinergic [choline acetyltransferase (CHAT) stained] neurons and total neurons were measured by immunohistochemical streptavidin-biotin complex (SABC) methods, Western blot and real-time polymerase chain reaction methods for each specimen. (i) Expression of GDNF was significantly decreased in diabetes 8 and 12 weeks group compared with the control group in both proximal (P < 0.01) and distal (P < 0.01) colon. The change of GDNF expression was greater in the 12 weeks group than that in the 8 weeks group (P < 0.05). There were no significant differences between the 4 weeks group and the control group in expression of GDNF (P > 0.05). (ii) The change trend of Akt phosphorylation was the same with GDNF. (iii) The numbers of nNOS, CHAT neurons and total neurons in proximal and distal colon were decreased significantly during the course of diabetes (P < 0.05). Diabetes can significantly induce enteric neuropathy. This change may be mediated, in partly, via a reduction of GDNF and its main downstream signalling pathway PI3K/Akt, which is a survival signal for enteric neurons.

Physiology, injury, and recovery of interstitial cells of Cajal: basic and clinical science

In the last 15 years, our understanding of the cellular basis of gastrointestinal function has been altered irreversibly by the discovery that normal gastrointestinal motility requires interstitial cells of Cajal (ICC). Research in this relatively short time period has modified our original concept that the core unit that controls motility is made up of nerves and smooth muscle, to one that now includes ICC. This concept has now expanded to beyond the gastrointestinal tract, suggesting that it may be a fundamental property of the regulation of smooth muscle function that requires rhythmic contraction. ICC are distributed throughout the gastrointestinal tract, have important functions in the control of gastrointestinal motility and are often abnormal in diseased states. Recently, significant steps forward have been made in our understanding of the physiology of ICC as well as mechanisms of injury and recovery. These advances will be the focus of this review.

Exploring the role of mast cells in eosinophilic esophagitis

The mast cell plays a critical role in allergic responses in the gastrointestinal tract and other sites. Emerging evidence indicates that mast cells also participate in the pathogenesis of eosinophilic esophagitis, although their precise role has not been defined. This article reviews the biology of mast cells and examines the potential involvement of the cell as an effector of the inflammatory response and tissue remodeling, and as a cell that has the potential to function as an immunomodulator and limit inflammation.

Loss of intramuscular and submuscular interstitial cells of Cajal and associated enteric nerves is related to decreased gastric emptying in streptozotocin-induced diabetes

Interstitial cells of Cajal (ICC) are associated with afferent innervation and peristalsis of the stomach suggestive of a key role in the pathophysiology of gastroparesis. We studied changes in the density and ultrastructure of ICC and enteric nerves in the streptozotocin-induced diabetes mellitus (STZ-DM) in Wistar rats using immunohistochemistry and electron microscopy. Gastric emptying was studied in vivo by single-photon emission computed tomography. In the STZ-DM antrum, a marked reduction was observed in the density of the intramuscular ICC (ICC-IM) and ICC located at the submucosal border of the circular muscle layer of the antrum (ICC-SM). The surviving ICC showed lamellar bodies and partial vacuolation of the cytoplasm content, loss of connections between ICC-IM and nerves; it appeared that injured ICC-IM developed into fibroblast-like ICC. ICC associated with Auerbach's plexus (ICC-AP) in the antrum and ICC in the fundus were not affected significantly except for a loss of connections with nerve structures. Marked reduction in nerve tissue (Protein Gene Product-9.5 positivity) was also restricted to the muscle layers including nitrergic nerves (neuronal nitric oxide synthase positivity). In vivo assessed gastric emptying was markedly reduced in STZ-DM rats. Our data demonstrate in the STZ-DM rat stomach a decreased density of ICC limited to the antrum and to ICC-IM and ICC-SM, and structural degeneration in ICC-IM and associated nerves with a special emphasis on loss of synaptic connections, accompanied by a decrease in gastric emptying. Hence, in this model of gastroparetic diabetes, regional injury to subsets of ICC and nerves are associated with gastric motor dysfunction.

Gastrointestinal neuromuscular pathology: guidelines for histological techniques and reporting on behalf of the Gastro 2009 International Working Group

The term gastrointestinal neuromuscular disease describes a clinically heterogeneous group of disorders of children and adults in which symptoms are presumed or proven to arise as a result of neuromuscular, including interstitial cell of Cajal, dysfunction. Such disorders commonly have impaired motor activity, i.e. slowed or obstructed transit with radiological evidence of transient or persistent visceral dilatation. Whilst sensorimotor abnormalities have been demonstrated by a variety of methods in these conditions, standards for histopathological reporting remain relatively neglected. Significant differences in methodologies and expertise continue to confound the reliable delineation of normality and specificity of particular pathological changes for disease. Such issues require urgent clarification to standardize acquisition and handling of tissue specimens, interpretation of findings and make informed decisions on risk-benefit of full-thickness tissue biopsy of bowel or other diagnostic procedures. Such information will also allow increased certainty of diagnosis, facilitating factual discussion between patients and caregivers, as well as giving prognostic and therapeutic information. The following report, produced by an international working group, using established consensus methodology, presents proposed guidelines on histological techniques and reporting for adult and paediatric gastrointestinal neuromuscular pathology. The report addresses the main areas of histopathological practice as confronted by the pathologist, including suction rectal biopsy and full-thickness tissue obtained with diagnostic or therapeutic intent. For each, indications, safe acquisition of tissue, histological techniques, reporting and referral recommendations are presented.

In situ recording from gut pacemaker cells

Interstitial cells of Cajal (ICC) associated with the myenteric plexus of the small intestine are crucial players in gut physiology performing pacemaker functions and directing peristalsis and segmentation. ICC have been studied after chemical isolation and under culture conditions, but concerns that these methods affect the intrinsic properties have hindered progress in our understanding of ICC. To overcome this problem, we have developed a method to obtain electrophysiological recordings from ICC in situ. The critical feature is the ability to make high resistance seals onto cells that are embedded within tissue to obtain patch clamp recordings. Our first results show a prominent presence of a chloride channel, one of the proposed ICC pacemaker channels. The developed method can be applied to auxiliary cells of the enteric nervous system such as glial cells or fibroblasts and will be ideal for the study of cell-cell communication in tissue.

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

BACKGROUND

The etiology of achalasia is still unknown. The current theories of chronic inflammation leading to autoimmune response with destruction and loss of the inhibitory myenteric ganglion cells enlighten its pathogenesis in a limited way only. Interstitial cells of Cajal (ICC) have been shown to be involved in nitrergic neurotransmission of the lower esophageal sphincter (LES).

AIM

To investigate the significance of ICC and neuronal nitric oxide synthase (n-NOS) in esophageal wall tissue of patients undergoing surgery for achalasia.

METHODS

In 53 patients with a median age of 45 (6-78) yr undergoing surgery for achalasia, the immunoreactivity of ICC (CD117/c-kit) and n-NOS was assessed. In 42 patients, biopsies were taken from the LES high-pressure zone during Heller myotomy, whereas in 11 patients with end-stage achalasia and a decompensated megaesophagus, the complete esophagus was resected. A semiquantitative analysis was carried out and ICC and n-NOS impairments were classified into four grades. Staining intensity was correlated with preoperative clinical, radiologic, and manometric findings and with long-term postoperative Eckardt score.

RESULTS

Grade III/IV ICC reduction (severe reduction to complete loss) was seen in 59.5% of all biopsy specimens of the LES high-pressure zone. Patients with grade III/IV ICC reduction had a significantly longer duration of achalasia symptoms (3 [0-43] yr) than patients with minor to marked (grade I/II) impairment (1 [0-16] yr, P= 0.028). A majority (72.5%) of tissue samples revealed severe reduction to complete loss of n-NOS immunoreactivity. The preoperative Eckardt score was statistically significantly different between patients with grade I/II and those with grade III/IV n-NOS reductions (P= 0.031). CD117 (c-kit) positivity was statistically significantly correlated with n-NOS staining intensity (correlation coefficient r= 0.781, P < 0.0001).

CONCLUSION

The present results suggest that in the pathogenesis of achalasia, especially in the development of the LES high-pressure zone, depletion of ICC networks and potential changes in the electrical activity of smooth muscle cells may play a crucial role. The reduction in CD117-positive ICC in a few patients also seemed to be of relevance, even if the cells of Auerbach's plexus were unscathed. The associated reduced NOS release might underlie the profound ICC impairment and could possibly be responsible for the lack of LES relaxation, because of missing inhibitory neurotransmission. It is unclear, however, whether the ICC loss is primarily caused by the accelerated attrition of mature cells or their impaired regeneration.

C-kit receptor in the human vas deferens: distinction of mast cells, interstitial cells and interepithelial cells

The molecular mechanisms underlying the regulation of vas deferens (VD) motility and semen emission are still poorly understood. Interstitial cells of Cajal (ICC), which harbour the c-kit receptor (CD117), provide the basis of coordinated gut motility. We investigated whether c-kit receptor-positive cells also exist in the normal human VD. Enzyme and fluorescence immunohistochemical techniques were applied on serial sections of human proximal, middle, and distal VD segments (n=49) employing 13 different monoclonal and polyclonal antibodies recognizing the c-kit receptor. The c-kit receptor was detected in either round- or spindle-shaped cells. On account of their antigenic profile, the round- and oval-shaped c-kit receptor-positive cells were identified as mast cells (MC) occurring in all layers of the VD except the epithelium. In contrast, two distinct populations of exclusively c-kit receptor-positive spindle-shaped cells were found within the lamina propria and, rarely, in the inner and outer smooth muscle layers, as well as within the epithelium. Different shaped c-kit receptor-positive MC and IC were present in all layers of the human VD. Our findings demonstrate the presence of different c-kit receptor-positive cells also in the human VD. Their rather ubiquitous distribution within the lamina propria and muscle layers suggests that IC and MC may modulate the neuromuscular transmission and the propagation of electrical signals in multiple systems involved in the draining of fluids. The importance of the c-kit receptor-positive interepithelial cells remains unclear.

Nitric oxide decreases the excitability of interstitial cells of Cajal through activation of the BK channel

Nitrergic nerves are structurally and functionally associated with ICC. To further understand mechanisms of communication, the hypothesis was investigated that NO might affect large conductance K channels. To that end, we searched for IbTX-sensitive currents in ICC obtained through explant cultures from the mouse small intestine and studied effects of the NOS inhibitor omega N-nitro-L-arginine (LNNA) and the NO donor sodium nitroprusside (SNP). IbTX-sensitive currents acquired in the whole-cell configuration through nystatin perforated patches exhibited high noise levels but relatively low amplitude, whereas currents obtained in the conventional whole-cell configuration exhibited less noise and higher amplitudes; depolarization from -80 to + 40 mV evoked 357 +/- 159 pA current in the nystatin perforated patch configuration and 1075 +/- 597 pA using the conventional whole-cell configuration. Immunohistochemistry showed that ICC associated with ganglia and Auerbach's plexus nerve fibers were immunoreactive to BK antibodies. The IbTX-sensitive currents were increased by SNP and inhibited by LNNA. BK blockers suppressed spontaneous transit outward currents in ICC. After block of BK currents, or before these currents became prominent, calcium currents were activated by depolarization in the same cells. Their peak amplitude occurred at -25 mV and the currents were increased with increasing extracellular calcium and inhibited by cobalt. The hypothesis is warranted that nitrergic innervation inhibits ICC excitability in part through activation of BK channels. In addition, NO is an intracellular regulator of ICC excitability.

C-Kit receptor (CD117) in the porcine urinary tract

C-Kit positive interstitial cells of Cajal (ICC) play an important role in the regulation of the smooth muscle motility, acting as internal pacemakers to provide the slow wave activity within various luminal organs. Recently c-Kit-(CD117)-positive interstitial cells (IC) have been shown in the genitourinary tract, but systematic studies on the distribution and density of IC within the urinary tract are still lacking. Therefore the aim of the present study was to analyze systematically the localization and distribution of the c-Kit receptor in the urinary tract of the pig using immunohistochemical and molecular methods. Tissue samples were harvested from the porcine urinary tract including renal calices and pelvis, ureteropelvic junction, proximal, middle and distal ureter, ureteral orifice, fundus, and corpus of the bladder and the internal urethral orifice. Small and large intestine specimen served as controls. Immunohistochemistry (APAAP, IF) was applied on serial frozen sections using four monoclonal and polyclonal antibodies recognizing CD117. Whole mounts of the porcine upper urinary tract were prepared and investigated using conventional and confocal fluorescence microscopy followed by three-dimensional reconstruction. UV-laser microdissection and RT-PCR were applied to confirm the immunohistochemical results. CD117-immunoreactivity labeled bipolar IC and round-shaped mast cells (MC) throughout the adventitia, tunica muscularis and submucosa within the whole porcine urinary tract. While MC were found continuously in all investigated segments, a gradient of bipolar IC was evident. The whole mount preparations gave a detailed cytomorphology of IC within the various layers of the porcine urinary tract. Whole mount preparations revealed closed apposition of bi- and tripolar c-Kit positive IC parallel to the smooth muscle bundles and to veins of the tunica muscularis and adventitia. In the urothelium single CD117-positive interepithelial cells were found. The highest density of CD117-positive cells was found at the ureteropelvic junction, however the differences in between the segments were minimal. Microdissection and RT-PCR confirmed the results uncovered by immunohistochemistry. The ubiquitous distribution of IC and their close relationship to smooth muscle provides strong evidence that IC could contribute to the intrinsic pacemaker activity within the porcine (upper and lower) urinary tract. The role of the interepithelial CD117-positive cells as mechanosensors or as a precursor cell in the regeneration of the urothelium, is conceivable.

Increase in stretch-induced rhythmic motor activity in the diabetic rat colon is associated with loss of ICC of the submuscular plexus

Diabetes affects many aspects of gastrointestinal motility, in part due to changes in interstitial cells of Cajal (ICC). The effect of diabetes on the colon, however, is not well characterized, and the aim of the present study was to investigate possible relationships between altered colonic motility as a consequence of streptozotocin-induced diabetes and injury to ICC. Physiological, immunohistochemical, and ultrastructural techniques were employed. The motor pattern of the rat colon was dominated by rhythmic high-amplitude, low-frequency contractions that were primarily myogenic in origin. These rhythmic contractions were induced by stretch associated with increased tension; the amplitude of the superimposed rhythmic contractions increased with increasing applied tension. In diabetic rats, the stretch-induced rhythmic contractile activity remained robust and of similar frequency but was significantly higher in amplitude compared with that in control rats. At 700 mg of applied tension, the force of contraction in circular colonic muscle strips of the diabetic rats was 370% of control values. This robust presence of low-frequency contractions is consistent with the unaffected pacemaker, the ICC associated with Auerbach's plexus, and the increased amplitude correlates with loss of and injury to ICC of the submuscular plexus and intramuscular ICC. Loss of inhibitory nitrergic nerves does not appear to be a factor based on unaltered nNOS immunoreactivity.

5-HT receptors on interstitial cells of Cajal, smooth muscle and enteric nerves

The majority of the body's serotonin (5-HT) is produced by the gastrointestinal tract. 5-HT has several functions in the gastrointestinal tract. 5-HT is a paracrine signalling molecule released from enterochromaffin cells, a survival and proliferating factor and a neurotransmitter. The actions of 5-HT are transduced by a large family of 5-HT receptors, several of which are expressed on different gastrointestinal cell types including enteric nerves, smooth muscle and interstitial cells of Cajal (ICC). This review will summarize recent advances in understanding the role of 5-HT in regulating function of ICC, and the expression and function of 5-HT receptors on muscle and enteric nerves in human tissue. Rodent ICC express several 5-HT receptors including 5-HT(2B) receptors which regulate ICC survival and proliferation. Human smooth muscle and enteric neurons also express several 5-HT receptor subtypes. Expression and function of these receptors is significantly different from small laboratory animals. 5-HT(7) receptor activation causes relaxation of muscle, whereas 5-HT(2B) receptors increase muscle activity. The 5-HT(4) receptor appears to mediate both inhibition and activation of smooth muscle involving myogenic as well as neural actions. Despite the abundant expression of 5-HT(3) receptors in the human enteric nervous system no functional correlate has been as yet demonstrated.