Achalasia. A possible late cause of postpolio dysphagia

You Talking to Me? Says the Enteric Nervous System (ENS) to the Microbe. How Intestinal Microbes Interact with the ENS

Mammalian organisms form intimate interfaces with commensal and pathogenic gut microorganisms. Increasing evidence suggests a close interaction between gut microorganisms and the enteric nervous system (ENS), as the first interface to the central nervous system. Each microorganism can exert a different effect on the ENS, including phenotypical neuronal changes or the induction of chemical transmitters that interact with ENS neurons. Some pathogenic bacteria take advantage of the ENS to create a more suitable environment for their growth or to promote the effects of their toxins. In addition, some commensal bacteria can affect the central nervous system (CNS) by locally interacting with the ENS. From the current knowledge emerges an interesting field that may shape future concepts on the pathogen-host synergic interaction. The aim of this narrative review is to report the current findings regarding the inter-relationships between bacteria, viruses, and parasites and the ENS.

Is There Any Evidence for a Viral Cause in Achalasia?

BACKGROUND

Achalasia, as an incurable disease is defined by the lack of normal esophageal peristalsis and loss of lower esophageal sphincter relaxation due to impaired myenteric neural plexus. The exact cause of myenteric neural cells degeneration in achalasia is still unknown. One hypothesis is that certain neurotropic viruses and autoimmune factors cause the inflammatory response in myenteric network, which consequently destroy neural cells. This study was designed to find the evidence of viral causes of achalasia.

METHODS

In this case-control study, 52 patients with achalasia and 50 controls referred to Shariati Hospital, were evaluated for the genome of neurotropic viruses, HPV, and adenovirus by polymerase chain reaction (PCR) and reverse transcription (RT) PCR techniques.

RESULTS

Genome assessment of neurotropic DNA viruses turned out negative in the patients, however, the genome of HSV-1 (Herpes simplex virus) was found in tissues of six controls. No neurotropic RNA viruses were observed in the tissue samples and whole blood of both the patients and controls. Among non-neurotropic viruses, adenovirus genome was positive in tissues of two out of 52 patients and three out of 50 controls. In addition, one out of 52 patients and two out of 50 controls were positive for HPV infection in tissues.

CONCLUSION

We could not detect any significant relationship between achalasia and HPV, adenovirus, and neurotropic viruses in the cases. Nevertheless, it does not exclude the hypothesis of either an alternate viral species or resolved viral infection as the etiology of achalasia.

Enhanced reactivity of peripheral blood immune cells to HSV-1 in primary achalasia

OBJECTIVE

Achalasia is the best characterized oesophageal motor disorder but the etiology is unknown. The pathology is characterized by a decrease in nitric oxide-producing neurons and the presence of an activated T-cell inflammatory infiltrate in the myenteric plexus that are reactive to HSV-1 viral antigens. These findings are not present in normal controls. The current study compared the reactivity of peripheral blood mononuclear cells (PBMCs) between patients with primary achalasia and normal controls to determine if PBMCs of patients exhibit a similar heightened reactivity to the virus.

MATERIAL AND METHODS

Whole blood culture experiments were conducted with heparinized peripheral venous blood obtained from 151 patients with primary achalasia and 118 healthy controls. Whole blood was cultured in the presence of ultraviolet inactivated HSV-1 or conditioned cell culture media. Reactivity of mononuclear cells to viral antigens was quantified by measuring expression of the cytokine gene interferon-gamma using Taqman real-time polymerase chain reaction. Data are expressed as cytokine fold change corresponding to ratio of interferon-gamma messenger RNA copies produced in antigen stimulated versus unstimulated cells.

RESULTS

The interferon-gamma fold change was higher in cases 61.33 (20.54-217.00) than controls 49.67 (10.05-157.05). Mean fold change difference between cases and controls was 1.66 times (95% confidence interval 1.17-2.34, p = 0.004).

CONCLUSIONS

These results indicate that the PBMCs of patients with primary achalasia show an enhanced immune response to HSV-1 antigens. The data suggest that there is persistent stimulation of immune cells by herpes simplex virus type 1 (HSV-1) or HSV-1 like antigen moieties.

Herpes simplex virus type 1 infection of the rat enteric nervous system evokes small-bowel neuromuscular abnormalities

BACKGROUND & AIMS

Infectious agents, such as neurotropic viruses, are proposed to disrupt the enteric neuromuscular system, leading to dysmotility, although the mechanisms are unknown. Our purpose was to assess whether herpes simplex virus type-1 (HSV-1) establishes an enteric-neuronal infection and induces gut dysmotility.

METHODS

Rats were inoculated with HSV-1 intranasally and after 4 weeks intragastrically. After 1-10 weeks, infection was determined by molecular analysis whereas neuromuscular function was evaluated by pharmacologic/electrical stimulation of longitudinal ileal segments and by gastrointestinal transit and by [(3)H]acetylcholine release measurements. Inflammation in the neuromuscular layer was assessed by myeloperoxidase and cytokine levels and by anti-CD3(+) immunohistochemistry.

RESULTS

After 1-10 weeks of intragastric inoculation, HSV-1 latency-associated messenger RNA transcripts were detected in the brain and in ileal neurons with no signs of illness or histologic gut abnormalities. By using a recombinant HSV-1 carrying the lacZ gene, HSV-1 virions were localized in myenteric ganglia by in situ X-gal staining. Interleukin-2 and IFN-gamma levels were increased significantly 1 and 6 weeks after inoculation. CD3(+) cells were found around the myenteric ganglia 6 weeks after inoculation. Smooth muscle responses to carbachol, CaCl(2), and gut transit were increased significantly after 1 and 6 weeks, whereas KCl- and electrical field stimulation-mediated contractions were modified significantly only 1-2 weeks after HSV-1 administration. The release of [(3)H]acetylcholine was reduced significantly in ileum segments after 1 and 6 weeks.

CONCLUSIONS

After intragastric inoculation, HSV-1 establishes a latent infection in the rat myenteric ganglia, which leads to gut dysmotility.

T cells in the myenteric plexus of achalasia patients show a skewed TCR repertoire and react to HSV-1 antigens

OBJECTIVE

The loss of myenteric neurons in the lower esophageal sphincter (LES) characterizes achalasia, an esophageal motor disorder. Because the presence of lymphocytic infiltrates suggests an immuno-mediated mechanism ongoing at the sites of disease, we investigated the T-cell receptor (TCR) repertoire and the ability to recognize human herpes virus type 1 (HSV-1) antigens of LES-infiltrating T lymphocytes in achalasia patients.

METHODS

Fifty-nine patients with idiopathic achalasia and 38 heart-beating cadaveric multiorgan donors (controls) were studied. By flow cytometry evaluation and CDR3 length spectratyping analysis, the lymphocytes of 18 patients and 15 controls were analyzed, whereas 41 patients and 23 controls were employed for functional assays.

RESULTS

Achalasia patients were characterized by a significantly higher esophagus lymphocytic infiltrate than controls (24.71%+/- 3.11 and 9.54%+/- 1.34, respectively; P < 0.05), mainly represented by CD3+CD8+ T cells. The characterization of TCR beta chain repertoire of CD3+ cells showed the expression of a limited number of TCR beta variable (BV) gene families (from two to five out of 26), with highly restricted spectratypes, suggesting a disease-associated oligoclonal selection of T cells. Furthermore, lymphocytes from achalasia LES specifically responded to exposure to HSV-1 antigens in vitro as showed by increased proliferation and Th-1 type cytokines release.

CONCLUSIONS

These data suggest that the oligoclonal lymphocytic infiltrate within the LES of achalasia patients may represent the trace of an immune-inflammatory reaction triggered by HSV-1 antigens and that the Th1-type cytokines released by the activated lymphocytes may contribute to establish the neuronal damage accounting for the clinical features of idiopathic achalasia.

Achalasia and thyroid disease

AIM: To investigate some possible etiologies of achalasia by screening patients with achalasia for some autoimmune diseases such as thyroid disease.

METHODS: We examined 30 known cases of achalasia (20 females, 10 males). Their age ranged 15-70 years. All of them were referred to our institute for treatment. Their sera were evaluated to detect some possible associations with rheumatoid disease, thyroid disease, inflammatory process, anemia, etc.

RESULTS: Seven out of 30 patients (23%) had thyroid disease including four patients with hypothyroidism (13.3%), two patients with hyperthyroidism (6.6%), and one had only thyroid nodule but was in euthyroid state (3.3%). Two of these hypothyroid patients had no related clinical symptoms (subclinical) and two had clinical manifestations of hypothyroidism. There were no correlations between the intensity of thyroid diseases and the severity of achalasia symptoms.

CONCLUSION: The etiology of achalasia is unknown although autoimmunity has been implicated and is supported by several studies. Thyroid disease presents concomitantly with achalasia in about one fourth of our patients who may have a common etiology.

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.

Laryngeal manifestations of postpoliomyelitis syndrome

Postpoliomyelitis syndrome (PPS) is a disease that may occur in survivors of acute poliomyelitis several decades after their initial infection. It can present as dysphonia, with vocal weakness and fatigue. Swallowing, respiratory, and other laryngopharyngeal symptoms may be manifestations of the disease or they may represent worsening of previously stable and compensated deficits. Three cases of laryngeal changes in PPS with videostroboscopic and laryngeal electromyography findings highlight the features of this disorder. We review possible etiologies of laryngeal PPS, diagnostic criteria, and treatment, as well as the current literature.