Interstitial cells of Cajal in chagasic megaesophagus

Profile of interstitial cells of Cajal in a murine model of chagasic megacolon

Disorders of gastrointestinal motility are the major physiologic problem in chagasic megacolon. The contraction mechanism is complex and controlled by different cell types such as enteric neurons, smooth muscle, telocytes, and an important pacemaker of the intestine, the interstitial cells of Cajal (ICCs). The role of ICCs in the progression of acute and chronic Chagas disease remains unclear. In the present work, we investigate the aspects of ICCs in a long-term model of Chagas disease that mimics the pathological aspects of human megacolon. Different subsets of ICCs isolated from Auerbach's myenteric plexuses and muscle layers of control and Trypanosoma cruzi infected animals were determined by analysis of CD117, CD44, and CD34 expression by flow cytometer. Compared with the respective controls, the results showed a reduced frequency of mature ICCs in the acute phase and three months after infection. These results demonstrate for the first time the phenotypic distribution of ICCs associated with functional dysfunction in a murine model of chagasic megacolon. This murine model proved valuable for studying the profile of ICCs as an integrative system in the gut and as a platform for understanding the mechanism of chagasic megacolon development.

INFLUENCE OF ESOPHAGEAL MOTILITY IMPAIRMENT ON UPPER AND LOWER ESOPHAGEAL SPHINCTER PRESSURE IN CHAGAS DISEASE

BACKGROUND

Chagas disease causes digestive anatomic and functional changes, including the loss of the myenteric plexus and abnormal esophageal radiologic and manometric findings.

OBJECTIVE

To evaluate the association of abnormal esophageal radiologic findings, cardiac changes, distal esophageal contractions, and complaints of dysphagia and constipation in upper (UES) and lower (LES) esophageal sphincter basal pressure in Chagas disease patients.

METHODS

The study evaluated 99 patients with Chagas disease and 40 asymptomatic normal volunteers. The patients had normal esophageal radiologic examination (n=61) or esophageal retention without an increase in esophageal diameter (n=38). UES and LES pressure was measured with the rapid pull-through method in a 4-channel water-perfused round catheter. Before manometry, the patients were asked about dysphagia and constipation and submitted to electrocardiography and chest radiography.

RESULTS

The amplitude of esophageal distal contraction decreased from controls to chagasic patients with esophageal retention. The proportion of failed and simultaneous contractions increased in patients with abnormal radiologic examination (P<0.01). There were no significant differences in UES and LES pressure between the groups. UES pressure was similar between Chagas disease patients with cardiomegaly (n=27, 126.5±62.7 mmHg) and those without it (n=72, 144.2±51.6 mmHg, P=0.26). Patients with constipation had lower LES pressure (n=23, 34.7±20.3 mmHg) than those without it (n=76, 42.9±20.5 mmHg, P<0.03).

CONCLUSION

Chagas disease patients with absent or mild esophageal radiologic involvement had no significant changes in UES and LES basal pressure. Constipation complaints are associated with decreased LES basal pressure.

Interstitial Cells of Cajal and Enteric Nervous System in Gastrointestinal and Neurological Pathology, Relation to Oxidative Stress

The enteric nervous system (ENS) is organized into two plexuses-submucosal and myenteric-which regulate smooth muscle contraction, secretion, and blood flow along the gastrointestinal tract under the influence of the rest of the autonomic nervous system (ANS). Interstitial cells of Cajal (ICCs) are mainly located in the submucosa between the two muscle layers and at the intramuscular level. They communicate with neurons of the enteric nerve plexuses and smooth muscle fibers and generate slow waves that contribute to the control of gastrointestinal motility. They are also involved in enteric neurotransmission and exhibit mechanoreceptor activity. A close relationship appears to exist between oxidative stress and gastrointestinal diseases, in which ICCs can play a prominent role. Thus, gastrointestinal motility disorders in patients with neurological diseases may have a common ENS and central nervous system (CNS) nexus. In fact, the deleterious effects of free radicals could affect the fine interactions between ICCs and the ENS, as well as between the ENS and the CNS. In this review, we discuss possible disturbances in enteric neurotransmission and ICC function that may cause anomalous motility in the gut.

Persistent Herpes Simplex Virus Type 1 Infection of Enteric Neurons Triggers CD8+ T Cell Response and Gastrointestinal Neuromuscular Dysfunction

Behind the central nervous system, neurotropic viruses can reach and persist even in the enteric nervous system (ENS), the neuronal network embedded in the gut wall. We recently reported that immediately following orogastric (OG) administration, Herpes simplex virus (HSV)-1 infects murine enteric neurons and recruits mononuclear cells in the myenteric plexus. In the current work, we took those findings a step forward by investigating the persistence of HSV-1 in the ENS and the local adaptive immune responses against HSV-1 that might contribute to neuronal damage in an animal model. Our study demonstrated specific viral RNA transcripts and proteins in the longitudinal muscle layer containing the myenteric plexus (LMMP) up to 10 weeks post HSV-1 infection. CD3⁺CD8⁺INFγ⁺ lymphocytes skewed towards HSV-1 antigens infiltrated the myenteric ganglia starting from the 6^th week of infection and persist up to 10 weeks post-OG HSV-1 inoculation. CD3⁺CD8⁺ cells isolated from the LMMP of the infected mice recognized HSV-1 antigens expressed by infected enteric neurons. In vivo, infiltrating activated lymphocytes were involved in controlling viral replication and intestinal neuromuscular dysfunction. Indeed, by depleting the CD8⁺ cells by administering specific monoclonal antibody we observed a partial amelioration of intestinal dysmotility in HSV-1 infected mice but increased expression of viral genes. Our findings demonstrate that HSV-1 persistently infects enteric neurons that in turn express viral antigens, leading them to recruit activated CD3⁺CD8⁺ lymphocytes. The T-cell responses toward HSV-1 antigens persistently expressed in enteric neurons can alter the integrity of the ENS predisposing to neuromuscular dysfunction.

Evaluation of the immunoreactivity of nerve growth factor and tropomyosin receptor kinase A in the esophagus of noninfected and infected individuals with Trypanosoma cruzi

Megaesophagus is one of the major manifestations of the chronic phase of Chagas disease. Its primary symptom is generally dysphagia due to disturbance in the lower esophageal sphincter. Microscopically, the affected organ presents denervation, which has been considered as consequence of an inflammatory process that begins at the acute phase and persists in the chronic phase. Inflammatory infiltrates are composed of lymphocytes, macrophages, natural killer cells, mast cells, and eosinophils. In this study, we evaluated the immunoreactivity of nerve growth factor (NGF), and of its receptor tropomyosin receptor kinase A (TrkA), molecules that are well known for having a relevant role in neuroimmune communication in the gastrointestinal tract. Esophageal samples obtained via autopsy or surgery procedures from six noninfected individuals, six infected individuals without megaesophagus, and six infected individuals with megaesophagus were analyzed. Infected individuals without megaesophagus presented increased numbers of NGF immunoreactive (IR) mast cells and increased areas of TrkA-IR epithelial cells and inner muscle cells. Infected individuals with megaesophagus showed increased numbers of NGF-IR eosinophils and mast cells, TrkA-IR eosinophils and mast cells, increased area of NGF-IR epithelial cells, and increased areas of TrkA-IR epithelials cells and inner muscle cells. The data presented here point to the participation of NGF and its TrkA receptor in the pathology of chagasic megaesophagus.

Trypanosoma cruzi Detection in Colombian Patients with a Diagnosis of Esophageal Achalasia

Achalasia is a motility disorder of the esophagus that might be secondary to a chronic Trypanosoma cruzi infection. Several studies have investigated esophageal achalasia in patients with Chagas disease (CD) in Latin America, but no related studies have been performed in Colombia. The goals of the present study were to determine the presence of anti-T. cruzi antibodies in patients with esophageal achalasia who visited a referral hospital in Bogotá, Colombia, and to detect the presence of the parasite and its discrete typing units (DTUs). This cross-sectional study was conducted in adult patients (18-65 years old) who were previously diagnosed with esophageal achalasia and from whom blood was drawn to assess antibodies against T. cruzi using four different serological tests. Trypanosoma cruzi DNA was detected by conventional polymerase chain reaction (cPCR) and quantitative polymerase chain reaction (qPCR). In total, 38 patients, with an average age of 46.6 years (standard deviation of ±16.2) and comprising 16 men and 22 women, were enrolled. Five (13.15%) patients were found to be positive for anti-T. cruzi antibodies by indirect immunofluorescence assay (IFA), and two patients who were negative according to IFA were reactive by both enzyme-linked immunosorbent assay and immunoblot (5.3%). Parasite DNA was detected in two of these seven patients by cPCR and in one of these by qPCR. The parasite DTU obtained was TcI. In summary, this study identified T. cruzi in Colombian patients with esophageal achalasia, indicating that digestive compromise could also be present in patients with chronic CD.

Gastrointestinal Parasites and the Neural Control of Gut Functions

Gastrointestinal motility and transport of water and electrolytes play key roles in the pathophysiology of diarrhea upon exposure to enteric parasites. These processes are actively modulated by the enteric nervous system (ENS), which includes efferent, and afferent neurons, as well as interneurons. ENS integrity is essential to the maintenance of homeostatic gut responses. A number of gastrointestinal parasites are known to cause disease by altering the ENS. The mechanisms remain incompletely understood. Cryptosporidium parvum, Giardia duodenalis (syn. Giardia intestinalis, Giardia lamblia), Trypanosoma cruzi, Schistosoma species and others alter gastrointestinal motility, absorption, or secretion at least in part via effects on the ENS. Recent findings also implicate enteric parasites such as C. parvum and G. duodenalis in the development of post-infectious complications such as irritable bowel syndrome, which further underscores their effects on the gut-brain axis. This article critically reviews recent advances and the current state of knowledge on the impact of enteric parasitism on the neural control of gut functions, and provides insights into mechanisms underlying these abnormalities.

Neurodegeneration and neuroregeneration in Chagas disease

Autonomic dysfunction plays a significant role in the development of chronic Chagas disease (CD). Destruction of cardiac parasympathetic ganglia can underlie arrhythmia and heart failure, while lesions of enteric neurons in the intestinal plexuses are a direct cause of aperistalsis and megasyndromes. Neuropathology is generated by acute infection when the parasite, though not directly damaging to neuronal cells, elicits immune reactions that can become cytotoxic, inducing oxidative stress and neurodegeneration. Anti-neuronal autoimmunity may further contribute to neuropathology. Much less clear is the mechanism of subsequent neuronal regeneration in patients that survive acute infection. Morphological and functional recovery of the peripheral neurons in these patients correlates with the absence of CD clinical symptoms, while persistent neuronal deficiency is observed for the symptomatic group. The discovery that Trypanosoma cruzi trans-sialidase can moonlight as a parasite-derived neurotrophic factor (PDNF) suggests that the parasite might influence the balance between neuronal degeneration and regeneration. PDNF functionally mimics mammalian neurotrophic factors in that it binds and activates neurotrophin Trk tyrosine kinase receptors, a mechanism which prevents neurodegeneration. PDNF binding to Trk receptors triggers PI3K/Akt/GSK-3β and MAPK/Erk/CREB signalling cascades which in neurons translates into resistance to oxidative and nutritional stress, and inhibition of apoptosis, whereas in the cytoplasm of infected cells, PDNF represents a substrate-activator of the host Akt kinase, enhancing host-cell survival until completion of the intracellular cycle of the parasite. Such dual activity of PDNF provides sustained activation of survival mechanisms which, while prolonging parasite persistence in host tissues, can underlie distinct outcomes of CD.

Esophageal Eosinophilia

The presence of esophageal eosinophilia encompasses a broad differential diagnosis, and at times a specific histologic diagnosis is not possible. This content provides a systematic approach to esophageal squamous eosinophilia with emphasis on specific, distinguishing features within this expansive differential.

What is new in esophageal injury (infection, drug-induced, caustic, stricture, perforation)?

PURPOSE OF REVIEW: We will focus separately on infectious, drug-induced and caustic injury of the esophagus and their possible complications such as stricture and perforation. RECENT FINDINGS: There has been a decrease in opportunistic esophageal infection in HIV-positive patients, in particular candidiasis, which remains an important cause of inpatient charges, length of stay and total hospital costs, and new antifungal therapy are currently explored. As far as drug-induced esophageal injury is concerned, more than 1000 cases of all cases due to nearly 100 different medications have been described during the last 10 years. However, the estimated case frequency is probably much higher and the related literature is of low quality, as cases are reported selectively and stimulated by clustering of cases, newly implicated pills or unusual complications. Finally, in the field of caustic ingestion-related injury, there has been greater understanding of geographical differences in prevalence and more frequently involved substances, choice of optimal timing for endoscopy, relationship between symptoms and severity of lesions and appropriate role of steroids and other therapies, such as the topical application of mytomicin C. SUMMARY: This update covers the most relevant papers published on the three areas of interest during the last year.

The chronic gastrointestinal manifestations of Chagas disease

Chagas disease is an infectious disease caused by the protozoan Trypanosoma cruzi. The disease mainly affects the nervous system, digestive system and heart. The objective of this review is to revise the literature and summarize the main chronic gastrointestinal manifestations of Chagas disease. The chronic gastrointestinal manifestations of Chagas disease are mainly a result of enteric nervous system impairment caused by T. cruzi infection. The anatomical locations most commonly described to be affected by Chagas disease are salivary glands, esophagus, lower esophageal sphincter, stomach, small intestine, colon, gallbladder and biliary tree. Chagas disease has also been studied in association with Helicobacter pylori infection, interstitial cells of Cajal and the incidence of gastrointestinal cancer.