The effect of vasoactive intestinal polypeptide on the lower esophageal sphincter in achalasia

A Synthetic Agonist to Vasoactive Intestinal Peptide Receptor-2 Induces Regulatory T Cell Neuroprotective Activities in Models of Parkinson's Disease

A paradigm shift has emerged in Parkinson’s disease (PD) highlighting the prominent role of CD4⁺ Tregs in pathogenesis and treatment. Bench to bedside research, conducted by others and our own laboratories, advanced a neuroprotective role for Tregs making pharmacologic transformation of immediate need. Herein, a vasoactive intestinal peptide receptor-2 (VIPR2) peptide agonist, LBT-3627, was developed as a neuroprotectant for PD-associated dopaminergic neurodegeneration. Employing both 6-hydroxydopamine (6-OHDA) and α-synuclein (α-Syn) overexpression models in rats, the sequential administration of LBT-3627 increased Treg activity without altering cell numbers both in naïve animals and during progressive nigrostriatal degeneration. LBT-3627 administration was linked to reductions of inflammatory microglia, increased survival of dopaminergic neurons, and improved striatal densities. While α-Syn overexpression resulted in reduced Treg activity, LBT-3627 rescued these functional deficits. This occurred in a dose-dependent manner closely mimicking neuroprotection. Taken together, these data provide the basis for the use of VIPR2 agonists as potent therapeutic immune modulating agents to restore Treg activity, attenuate neuroinflammation, and interdict dopaminergic neurodegeneration in PD. The data underscore an important role of immunity in PD pathogenesis.

Management of achalasia cardia: Expert consensus statements

Achalasia cardia (AC) is a frequently encountered motility disorder of the esophagus resulting from an irreversible degeneration of neurons. Treatment modalities are palliative in nature, and there is no curative treatment available for AC as of now. Significant advancements have been made in the management of AC over last decade. The introduction of high resolution manometry and per-oral endoscopic myotomy (POEM) has strengthened the diagnostic and therapeutic armamentarium of AC. High resolution manometry allows for the characterization of the type of achalasia, which in turn has important therapeutic implications. The endoscopic management of AC has been reinforced with the introduction of POEM that has been found to be highly effective and safe in palliating the symptoms in short-term to mid-term follow-up studies. POEM is less invasive than Heller's myotomy and provides the endoscopist with the opportunity of adjusting the length and orientation of esophageal myotomy according to the type of AC. The management of achalasia needs to be tailored for each patient, and the role of pneumatic balloon dilatation, POEM, or Heller's myotomy needs to be revisited. In this review, we discuss the important aspects of diagnosis as well as management of AC. The statements presented in the manuscript reflect the cumulative efforts of an expert consensus group.

The Pathogenesis and Management of Achalasia: Current Status and Future Directions

Achalasia is an esophageal motility disorder that is commonly misdiagnosed initially as gastroesophageal reflux disease. Patients with achalasia often complain of dysphagia with solids and liquids but may focus on regurgitation as the primary symptom, leading to initial misdiagnosis. Diagnostic tests for achalasia include esophageal motility testing, esophagogastroduodenoscopy and barium swallow. These tests play a complimentary role in establishing the diagnosis of suspected achalasia. High-resolution manometry has now identified three subtypes of achalasia, with therapeutic implications. Pneumatic dilation and surgical myotomy are the only definitive treatment options for patients with achalasia who can undergo surgery. Botulinum toxin injection into the lower esophageal sphincter should be reserved for those who cannot undergo definitive therapy. Close follow-up is paramount because many patients will have a recurrence of symptoms and require repeat treatment.

The spectrum of achalasia: lessons from studies of pathophysiology and high-resolution manometry

High-resolution manometry and recently described analysis algorithms, summarized in the Chicago Classification, have increased the recognition of achalasia. It has become apparent that the cardinal feature of achalasia, impaired lower esophageal sphincter relaxation, can occur in several disease phenotypes: without peristalsis, with premature (spastic) distal esophageal contractions, with panesophageal pressurization, or with peristalsis. Any of these phenotypes could indicate achalasia; however, without a disease-specific biomarker, no manometric pattern is absolutely specific. Laboratory studies indicate that achalasia is an autoimmune disease in which esophageal myenteric neurons are attacked in a cell-mediated and antibody-mediated immune response against an uncertain antigen. This autoimmune response could be related to infection of genetically predisposed subjects with herpes simplex virus 1, although there is substantial heterogeneity among patients. At one end of the spectrum is complete aganglionosis in patients with end-stage or fulminant disease. At the opposite extreme is type III (spastic) achalasia, which has no demonstrated neuronal loss but only impaired inhibitory postganglionic neuron function; it is often associated with accentuated contractility and could be mediated by cytokine-induced alterations in gene expression. Distinct from these extremes is progressive plexopathy, which likely arises from achalasia with preserved peristalsis and then develops into type II achalasia and then type I achalasia. Variations in its extent and rate of progression are likely related to the intensity of the cytotoxic T-cell assault on the myenteric plexus. Moving forward, we need to integrate the knowledge we have gained into treatment paradigms that are specific for individual phenotypes of achalasia and away from the one-size-fits-all approach.

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

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

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.

The nervous system and gastrointestinal function

The enteric nervous system is an integrative brain with collection of neurons in the gastrointestinal tract which is capable of functioning independently of the central nervous system (CNS). The enteric nervous system modulates motility, secretions, microcirculation, immune and inflammatory responses of the gastrointestinal tract. Dysphagia, feeding intolerance, gastroesophageal reflux, abdominal pain, and constipation are few of the medical problems frequently encountered in children with developmental disabilities. Alteration in bowel motility have been described in most of these disorders and can results from a primary defect in the enteric neurons or central modulation. The development and physiology of the enteric nervous system is discussed along with the basic mechanisms involved in controlling various functions of the gastrointestinal tract. The intestinal motility, neurogastric reflexes, and brain perception of visceral hyperalgesia are also discussed. This will help better understand the pathophysiology of these disorders in children with developmental disabilities.

Regulation of basal tone, relaxation and contraction of the lower oesophageal sphincter. Relevance to drug discovery for oesophageal disorders

The lower oesophageal sphincter (LOS) is a specialized region of the oesophageal circular smooth muscle that allows the passage of a swallowed bolus to the stomach and prevents the reflux of gastric contents into the oesophagus. The anatomical arrangement of the LOS includes semicircular clasp fibres adjacent to the lesser gastric curvature and sling fibres following the greater gastric curvature. Such anatomical arrangement together with an asymmetric intrinsic innervation and distinct proportion of neurotransmitters in both regions produces an asymmetric pressure profile. The LOS tone is myogenic in origin and depends on smooth muscle properties that lead to opening of L-type Ca(2+) channels; however it can be modulated by enteric motor neurons, the parasympathetic and sympathetic extrinsic nervous system and several neurohumoral substances. Nitric oxide synthesized by neuronal NOS is the main inhibitory neurotransmitter involved in LOS relaxation. Different putative neurotransmitters have been proposed to play a role together with NO. So far, only ATP or related purines have shown to be co-transmitters with NO. Acetylcholine and tachykinins are involved in the LOS contraction acting through acetylcholine M(3) and tachykinin NK(2) receptors. Nitric oxide can also be involved in the regulation of LOS contraction. The understanding of the mechanisms that originate and modulate LOS tone, relaxation and contraction and the characterization of neurotransmitters and receptors involved in LOS function are important to develop new pharmacological tools to treat primary oesophageal motor disorders and gastro-oesophageal reflux disease.

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Etiology and pathogenesis of achalasia: the current understanding

Idiopathic achalasia is an inflammatory disease of unknown etiology characterized by esophageal aperistalsis and failure of LES relaxation due to loss of inhibitory nitrinergic neurons in the esophageal myenteric plexus. Proposed causes of achalasia include gastroesophageal junction obstruction, neuronal degeneration, viral infection, genetic inheritance, and autoimmune disease. Current evidence suggests that the initial insult to the esophagus, perhaps a viral infection or some other environmental factor, results in myenteric plexus inflammation. The inflammation then leads to an autoimmune response in a susceptible population who may be genetically predisposed. Subsequently, chronic inflammation leads to destruction of the inhibitory myenteric ganglion cells resulting in the clinical syndrome of idiopathic achalasia. Further studies are needed to better understand the etiology and pathogenesis of achalasia-such an understanding will be important in developing safe, effective, and possibly curative therapy for achalasia.

Review article: therapeutic roles of acupuncture in functional gastrointestinal disorders

Acupuncture has been practiced empirically in China for several millennia, and is being increasingly accepted by practitioners and patients worldwide. Functional gastrointestinal disorders are common in clinical gastroenterology. The prevalence of one or more functional gastrointestinal disorders is estimated to be as high as 70% in general population using Rome diagnostic criteria. Since functional gastrointestinal disorders are diagnosed based on symptoms and the exact aetiologies for most of functional gastrointestinal disorders are not completely known, it is not unusual that the treatment for these disorders is unsatisfactory and alternative therapies are attractive to both patients and practitioners. During the latest decades, a considerable number of studies have been performed on acupuncture for the treatment of functional gastrointestinal disorders and underlying mechanisms. In this article, we reviewed available data in the literature on the applications and mechanisms of acupuncture for the treatment of functional gastrointestinal disorders, including functional oesophageal disorders, nausea and vomiting, functional dyspepsia, irritable bowel syndrome, constipation, etc. A summary is provided based on the quality and quantity of published studies regarding the efficacy of acupuncture in treating these various disorders. In addition, the methodology of acupuncture is also introduced.

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Anorectal motility in patients with achalasia of the esophagus: recognition of an esophago-rectal syndrome

BACKGROUND

During my study of constipation, I encountered patients who had achalasia of the esophagus (AE) as well. The possibility of an existing relationship between the 2 conditions was studied.

METHOD

Investigations to study the anorectal motility in 9 AE patients included: the intestinal transit time, anorectal manometry, rectoanal inhibitory reflex, defecography and electromyography (EMG) of external anal sphincter and levator ani muscle. Anorectal biopsy was done. The study comprised 8 healthy volunteers as controls.

RESULTS

6/9 AE patients had constipation presenting as strainodynia (excessive prolonged straining at stool). Rectocele was present in 4 of them. The 6 constipated patients showed significantly high rectal neck pressure (p < 0.05), absent rectoanal inhibitory reflex and aganglionosis in the anorectal biopsy. The EMG revealed diminished activity in 4 of the 6 constipated patients. The remaining 3 patients with AE had normal anorectal function. Heller's myotomy with Nissen's fundoplication improved the dysphagia, but not the constipation which was, however, relieved after performance of anorectal myectomy.

CONCLUSION

The high incidence of constipation with AE postulates a relationship between the 2 conditions. Both have the same pathologic lesion which is aganglionosis. This study is preliminary and requires further studies on a larger number of patients.

Review article: pharmacological options in achalasia

Achalasia is a common primary oesophageal motor disorder. Treatment has been based traditionally on a surgical approach; however, there is new evidence that some medical strategies may be of benefit. The purpose of the present article was to review the current medical management of achalasia. A Medline search identified original articles and reviews published in the English-language literature between 1966 and 1998. This search has revealed that the pharmacological treatment of achalasia is limited to some subgroups of patients (for example, early stages of the disease and elderly patients), and that nitrates, nifedipine, and botulinum toxin are the best studied and most effective compounds.

Acupuncture for gastrointestinal and hepatobiliary disorders

Acupuncture has been used for various gastrointestinal (GI) conditions. Voluminous data support the effect of acupuncture on the physiology of the GI tract, including acid secretion, motility, neurohormonal changes, and changes in sensory thresholds. Much of the neuroanatomic pathway of these effects has been identified in animal models. A large body of clinical evidence supports the effectiveness of acupuncture for suppressing nausea associated with chemotherapy, postoperative state, and pregnancy. Prospective randomized controlled trials have also shown the efficacy of acupuncture for analgesia for endoscopic procedures, including colonoscopy and upper endoscopy. Acupuncture has also been used for a variety of other conditions including postoperative ileus, achalasia, peptic ulcer disease, functional bowel diseases (including irritable bowel syndrome and nonulcer dyspepsia), diarrhea, constipation, inflammatory bowel disease, expulsion of gallstones and biliary ascariasis, and pain associated with pancreatitis. Although there are few prospective randomized clinical studies, the well-documented physiological basis of acupuncture effects on the GI tract, and the extensive history of successful clinical use of acupuncture, makes this a promising modality that warrants further investigation.

Distribution of peptide-containing nerve fibres in achalasia of the oesophagus

In this study the innervation of the normal human oesophagus was compared with samples taken from 12 patients undergoing Heller's cardiomyotomy for achalasia. The distribution of all nerve fibres in the oesophageal wall was revealed by immunoreactivity to neuron specific enolase and subpopulations of nerve fibres were revealed by immunoreactivity to vasoactive intestinal peptide, neuropeptide Y, enkephalin and substance P. In healthy oesophagus, many nerve fibres immunoreactive for vasoactive intestinal peptide and neuropeptide Y were present in the circular and longitudinal muscle layers of the oesophageal wall and in the cardia of the stomach, whereas fibres immunoreactive for enkephalin and substance P were uncommon. Neuropeptide Y-reactive fibres were commonly seen around blood vessels. In the myenteric plexus cell bodies reactive for vasoactive intestinal peptide and neuropeptide Y were prevalent, as were varicose and non-varicose fibres. In contrast, samples from patients with achalasia revealed few nerve fibres immunoreactive for vasoactive intestinal peptide or neuropeptide Y in either circular or longitudinal muscle, suggesting damage to the inhibitory motor neurons to the muscle layers. Very few fibres were found that were reactive for neuron-specific enolase, indicating that other fibre population (e.g. excitatory cholinergic motor neurons) are also damaged in achalasia. These abnormalities were observed in biopsies from both the constricted and dilated portions of the oesophagus, but the pattern of innervation in the gastric cardia was normal. Myenteric ganglion cells were seen in the oesophagus in only two patients and varicose nerve fibres in the myenteric plexus were uncommon. Neuropeptide Y-reactive perivascular nerve fibres were still found in achalasia as well as non-varicose nerve fibres in the myenteric plexus. These findings indicate damage to all intrinsic neurons in the oesophageal wall in achalasia; however, extrinsic nerve fibres appear to be intact.

Different neurotransmitter systems are involved in the development of esophageal achalasia

Clinical and pharmacological evidence suggests that several neurotransmitters are involved in the control of the esophageal motility; in fact, besides the well known cholinergic and sympathetic innervation, Vasoactive Intestinal Polypeptide (VIP)-containing fibers as well as dopamine (DA)-containing nerve endings have been identified within the esophageal wall. Lower Esophageal Sphincter (LES) achalasia is a neuromuscular disorder characterized by the absence of peristalsis in the body of the esophagus and by the failure of the LES to relax in response to swallowing. Stimulation of both VIP receptors and D-2 DA receptors induce a decrease in LES pressure, while D-1 receptors mediates LES contractions. In the present study we show that both VIP and DA system is disregulated in LES achalasia. In particular, this disease is associated not only with the lack of VIP nerves in the LES, but also with a failure in the responsiveness of postsynaptic receptors to VIP stimulation. Furthermore, we demonstrate a selective functional loss of the D-2 DA receptor component, without changes in the D-1 DA receptor mediated responses.