Ileocolic Intussusception as the Presenting Symptom of Primary Enteric Varicella-Zoster Virus Infection in a 7-Month-Old Infant.

Ileocolic intussusception is the invagination of ileum into the colon. In a subset of patients, the disease is caused by mesenteric lymphadenopathy in response to (viral) infection. We present a case of an ileocolic intussusception necessitating surgery in a 7-month-old immunocompetent infant with concurrent primary wild-type varicella-zoster virus (VZV) infection, in whom chickenpox rash developed 2 days after surgery. Detailed in situ analyses of resected intestine for specific cell type markers and VZV RNA demonstrated VZV-infected lymphocytes and neurons in the gut wall and in ganglion cells of the myenteric plexus.

Herpes Simplex Virus Type 1 Infects Enteric Neurons and Triggers Gut Dysfunction via Macrophage Recruitment.

Herpes Simplex Virus type 1 (HSV-1), a neurotropic pathogen widespread in human population, infects the enteric nervous system (ENS) in humans and rodents and causes intestinal neuromuscular dysfunction in rats. Although infiltration of inflammatory cells in the myenteric plexus and neurodegeneration of enteric nerves are common features of patients suffering from functional intestinal disorders, the proof of a pathogenic link with HSV-1 is still unsettled mainly because the underlying mechanisms are largely unknown. In this study we demonstrated that following intragastrical administration HSV-1 infects neurons within the myenteric plexus resulting in functional and structural alterations of the ENS. By infecting mice with HSV-1 replication-defective strain we revealed that gastrointestinal neuromuscular anomalies were however independent of viral replication. Indeed, enteric neurons exposed to UV-inactivated HSV-1 produced monocyte chemoattractant protein-1 (MCP-1/CCL2) to recruit activated macrophages in the longitudinal muscle myenteric plexus. Infiltrating macrophages produced reactive oxygen and nitrogen species and directly harmed enteric neurons resulting in gastrointestinal dysmotility. In HSV-1 infected mice intestinal neuromuscular dysfunctions were ameliorated by in vivo administration of (i) liposomes containing dichloromethylene bisphosphonic acid (clodronate) to deplete tissue macrophages, (ii) CCR2 chemokine receptor antagonist RS504393 to block the CCL2/CCR2 pathway, (iii) Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) and AR-C 102222 to quench production of nitrogen reactive species produced via iNOS. Overall these data demonstrate that HSV-1 infection makes enteric neurons recruit macrophages via production of a specific chemoattractant factor. The resulting inflammatory reaction is mandatory for intestinal dysmotility. These findings provide insights into the neuro-immune communication that occurs in the ENS following HSV-1 infection and allow recognition of an original pathophysiologic mechanism underlying gastrointestinal diseases as well as identification of novel therapeutic targets.

Saccharomyces boulardii CNCM I-745 supplementation reduces gastrointestinal dysfunction in an animal model of IBS.

BACKGROUND: We evaluated the effect of Saccharomyces boulardii CNCM I-745 on intestinal neuromuscular anomalies in an IBS-type mouse model of gastrointestinal motor dysfunctions elicited by Herpes Simplex Virus type 1 (HSV-1) exposure. METHODS: Mice were inoculated intranasally with HSV-1 (102 PFU) or vehicle at time 0 and 4 weeks later by the intragastric (IG) route (108 PFU). Six weeks after IG inoculum, mice were randomly allocated to receive oral gavage with either S. boulardii (107 CFU/day) or vehicle. After 4 weeks the following were determined: a) intestinal motility using fluorescein-isothiocyanate dextran distribution in the gut, fecal pellet expulsion, stool water content, and distal colonic transit of glass beads; b) integrity of the enteric nervous system (ENS) by immunohistochemistry on ileal whole-mount preparations and western blot of protein lysates from ileal longitudinal muscle and myenteric plexus; c) isometric muscle tension with electric field and pharmacological (carbachol) stimulation of ileal segments; and d) intestinal inflammation by levels of tumor necrosis factor α, interleukin(IL)-1ß, IL-10 and IL-4. RESULTS: S. boulardii CNCM I-745 improved HSV-1 induced intestinal dysmotility and alteration of intestinal transit observed ten weeks after IG inoculum of the virus. Also, the probiotic yeast ameliorated the structural alterations of the ENS induced by HSV-1 (i.e., reduced peripherin immunoreactivity and expression, increased glial S100ß protein immunoreactivity and neuronal nitric oxide synthase level, reduced substance P-positive fibers). Moreover, S. boulardii CNCM I-745 diminished the production of HSV-1 associated pro-inflammatory cytokines in the myenteric plexus and increased levels of anti-inflammatory interleukins. CONCLUSIONS: S. boulardii CNCM I-745 ameliorated gastrointestinal neuromuscular anomalies in a mouse model of gut dysfunctions typically observed with irritable bowel syndrome.

Proof-of-concept: neonatal intravenous injection of adeno-associated virus vectors results in successful transduction of myenteric and submucosal neurons in the mouse small and large intestine.

BACKGROUND: Despite the success of viral vector technology in the transduction of the central nervous system in both preclinical research and gene therapy, its potential in neurogastroenterological research remains largely unexploited. This study asked whether and to what extent myenteric and submucosal neurons in the ileum and distal colon of the mouse were transduced after neonatal systemic delivery of recombinant adeno-associated viral vectors (AAVs). METHODS: Mice were intravenously injected at postnatal day one with AAV pseudotypes AAV8 or AAV9 carrying a cassette encoding enhanced green fluorescent protein (eGFP) as a reporter under the control of a cytomegalovirus promoter. At postnatal day 35, transduction of the myenteric and submucosal plexuses of the ileum and distal colon was evaluated in whole-mount preparations, using immunohistochemistry to neurochemically identify transduced enteric neurons. KEY RESULTS: The pseudotypes AAV8 and AAV9 showed equal potential in transducing the enteric nervous system (ENS), with 25-30% of the neurons expressing eGFP. However, the percentage of eGFP-expressing colonic submucosal neurons was significantly lower. Neurochemical analysis showed that all enteric neuron subtypes, but not glia, expressed the reporter protein. Intrinsic sensory neurons were most efficiently transduced as nearly 80% of calcitonin gene-related peptide-positive neurons expressed the transgene. CONCLUSIONS & INFERENCES: The pseudotypes AAV8 and AAV9 can be employed for gene delivery to both the myenteric and the submucosal plexus, although the transduction efficiency in the latter is region-dependent. These findings open perspectives for novel preclinical applications aimed at manipulating and imaging the ENS in the short term, and in gene therapy in the longer term.

Achalasia--An Autoimmune Inflammatory Disease: A Cross-Sectional Study.

Idiopathic achalasia is a disease of unknown etiology. The loss of myenteric plexus associated with inflammatory infiltrates and autoantibodies support the hypothesis of an autoimmune mechanism. Thirty-two patients diagnosed by high-resolution manometry with achalasia were included. Twenty-six specimens from lower esophageal sphincter muscle were compared with 5 esophagectomy biopsies (control). Immunohistochemical (biopsies) and flow cytometry (peripheral blood) analyses were performed. Circulating anti-myenteric autoantibodies were evaluated by indirect immunofluorescence. Herpes simplex virus-1 (HSV-1) infection was determined by in situ hybridization, RT-PCR, and immunohistochemistry. Histopathological analysis showed capillaritis (51%), plexitis (23%), nerve hypertrophy (16%), venulitis (7%), and fibrosis (3%). Achalasia tissue exhibited an increase in the expression of proteins involved in extracellular matrix turnover, apoptosis, proinflammatory and profibrogenic cytokines, and Tregs and Bregs versus controls (P < 0.001). Circulating Th22/Th17/Th2/Th1 percentage showed a significant increase versus healthy donors (P < 0.01). Type III achalasia patients exhibited the highest inflammatory response versus types I and II. Prevalence of both anti-myenteric antibodies and HSV-1 infection in achalasia patients was 100% versus 0% in controls. Our results suggest that achalasia is a disease with an important local and systemic inflammatory autoimmune component, associated with the presence of specific anti-myenteric autoantibodies, as well as HSV-1 infection.

Adenosine-mediated enteric neuromuscular function is affected during herpes simplex virus type 1 infection of rat enteric nervous system.

Adenosine plays an important role in regulating intestinal motility and inflammatory processes. Previous studies in rodent models have demonstrated that adenosine metabolism and signalling are altered during chronic intestinal inflammatory diseases. However, the involvement of the adenosinergic system in the pathophysiology of gut dysmotility associated to a primary neurodysfunction is still unclear. Recently, we showed that the neurotropic Herpes simplex virus type-1 (HSV-1), orally inoculated to rodents, infects the rat enteric nervous system (ENS) and affects gut motor function without signs of systemic infection. In this study we examined whether changes in purinergic metabolism and signaling occur during permanent HSV-1 infection of rat ENS. Using isolated organ bath assays, we found that contraction mediated by adenosine engagement of A1 or A2A receptors was impaired at 1 and 6 weeks post-viral administration. Immunofluorescence studies revealed that viral infection of ENS led to a marked redistribution of adenosine receptors: A1 and A2B receptors were confined to the muscle layers whereas A2A and A3 receptors were expressed mainly in the myenteric plexus. Viral-induced ENS neurodysfunction influenced adenosine metabolism by increasing adenosine deaminase and CD73 levels in longitudinal muscle-myenteric plexus with no sign of frank inflammation. This study provides the first evidence for involvement of the adenosinergic system during HSV-1 infection of the ENS. As such, this may represent a valid therapeutic target for modulating gut contractility associated to a primary neurodysfunction.

Extensive myenteric ganglionitis in a case of equine chronic intestinal pseudo-obstruction associated with EHV-1 infection.

A 7-year-old male trotter horse with a history of recurrent colic displayed clinical findings consistent with chronic intestinal pseudo-obstruction (CIP). At laparotomy, an impaction of the descending colon associated with marked atrophy of the right dorsal colon was found. The horse was humanely destroyed and tissues collected at necropsy examination revealed diffuse enteric ganglionitis comprising an infiltrate of CD3(+) T lymphocytes and plasma cells. At all levels of the intestinal tract the number of myenteric ganglia and of normal ganglion cells was decreased significantly. There were chromatolytic or necrotic neurons and the amount of connective tissue surrounding ganglia was increased. Immunohistochemical studies demonstrated slightly reduced expression of neuron-specific enolase and a moderate increase in expression of S100 and glial fibrillary acidic protein in a sample of right dorsal colon taken during the necropsy examination compared with a biopsy sample taken from the same location. Immunolabelling and semi-nested polymerase chain reaction for equine herpesvirus (EHV)-1 performed on the gut were positive, supporting an aetiological relationship between EHV-1 infection and the enteric ganglionitis.

JC virus infects the enteric glia of patients with chronic idiopathic intestinal pseudo-obstruction.

BACKGROUND AND AIMS: Chronic idiopathic intestinal pseudo-obstruction (CIIP) is characterised by severe impairment of intestinal propulsive motility that mimics bowel obstruction. JC virus (JCV) is a polyomavirus that can infect brain glial cells causing a fatal disease, but may also be found throughout the normal gastrointestinal tract. The hypothesis that JCV infects the myenteric plexuses of patients with CIIP was tested. METHODS: 10 patients with CIIP and 61 normal specimens (30 ascending colon and 31 ileum) from patients with uncomplicated colon cancer were studied. DNA was extracted from the myenteric plexuses, and JCV T antigen (TAg) DNA and the viral regulatory region were detected by PCR and sequencing. Immunohistochemistry was performed to detect JCV viral protein expression, neuronal and glial markers. Fluorescence in situ hybridisation was performed for cellular localisation of the JCV infection. RESULTS: Clinical studies demonstrated neurogenic impairment, and pathological analyses showed neuropathy in each patient with CIIP. JCV TAg DNA was found in the myenteric plexuses of 8/10 (80%) of the patients with CIIP and 3/31 (9.7%) of the control patients (p<0.001). All samples were JCV Mad-1 strains. Seven of the 10 CIIP specimens expressed both JCV TAg and the JCV viral protein VP1, while none of the controls expressed either. JCV infection co-localised with glial fibrillary acidic protein expression, a marker of enteric glial cells. CONCLUSION: JCV infection occurs in the myenteric plexuses of patients with CIIP. The JCV localisation in enteroglial cells suggests a possible pathological role for this virus in enteric neuropathy.

Infection of the enteric nervous system by Borna disease virus (BDV) upregulates expression of Calbindin D-28k.

Borna disease virus (BDV) is a neurotropic agent infecting distinct neuronal subpopulations in the central nervous system of various mammalian species possibly including humans. Horses, a major natural host for BDV, show gastrointestinal dysfunctions besides characteristic neurological symptoms. Therefore, we hypothesized that enteric neurons may be targets of BDV replication. The presence of BDV-specific antigen in subpopulations of the ENS was investigated. Four-week-old Lewis rats were infected intracerebrally and sacrificed 4-14 weeks post infection (p.i.). BDV-immunoreactive neurons were found in submucous and myenteric neurons of the proximal colon. Fourteen weeks p.i., the proportion of BDV-positive neurons was 44+/-17 and 24+/-7% in the submucous and myenteric plexus, respectively. The majority of BDV-positive myenteric neurons showed immunoreactivity for choline acetyltransferase. Expression of Calbindin D-28k (CALB) was found in 96% of submucous and 67% of myenteric BDV-immunoreactive neurons. Additionally, the number of CALB-immunoreactive neurons was significantly higher in the myenteric plexus of infected rats compared to controls. These data indicate that BDV infects specific subpopulations of enteric neurons. Therefore, the ENS might serve as a site for BDV replication and as an immunoprivileged reservoir for BDV. In addition, upregulation of CALB in neurons of the myenteric plexus is probably induced during BDV-infection.

Pathologic changes in closed porcine intestinal loops inoculated with Aujeszky's disease virus.

Development of enteric lesions in closed jejunal and ileal loops inoculated with Aujeszky's disease virus (ADV) was examined in four 6-week-old SPF pigs. A large number of ADV antigens were detected first in necrotic foci in the subepithelial areas, and subsequently in the epithelial cells, lymphoid follicles in Peyer's patches and neuronal cells of Meissner's and Auerbach's plexuses.

Oral inoculation with herpes simplex virus type 1 infects enteric neuron and mucosal nerve fibers within the gastrointestinal tract in mice.

Herpes simplex virus type 1 (HSV-1) is commonly encountered first during childhood as an oral infection. After this initial infection resolves, the virus remains in a latent form within innervating sensory ganglia for the life of the host. We have previously shown, using a murine model, that HSV-1 placed within the lumen of the esophagus gains access to nerves within the gut wall and establishes a latent infection in sensory ganglia (nodose ganglia) of the tenth cranial nerve (R. M. Gesser, T. Valyi-Nagy, S. M. Altschuler, and N. W. Fraser, J. Gen. Virol. 75:2379-2386, 1994). Peripheral processes of neurons in these ganglia travel through the vagus nerve and function as primary sensory receptors in most of the gastrointestinal tract, relaying information from the gut wall and mucosal surface to secondary neurons within the brain stem. In the work described here, we further examined the spread of HSV-1 through the enteric nervous system after oral inoculation. By immunohistochemistry, HSV-1 was found to infect myenteric ganglia in Auerbach's plexus between the inner and outer muscle layers of the gut wall, submucosal ganglia (Meisner's plexus), and periglandular ganglion plexuses surrounding submucosal glands. Virus-infected nerve fibers were also seen projecting through the mucosal layer to interact directly with surface epithelial cells. These intramucosal nerve fibers may be a conduit by which intraluminal virus is able to gain access to the enteric nervous system from the gastrointestinal lumen.

Gastrointestinal and skin lesions in piglets naturally infected with pseudorabies virus.

Pseudorabies virus (PRV) infection was diagnosed in 4 piglets from a litter by immunohistopathologic examination and virus isolation. Three piglets had moderate to severe neuronal degeneration, and PRV antigen was detected in Auerbach's myenteric plexus and Meissner's submucosal plexus of the gastrointestinal tract. One piglet had 2 types of skin lesions. One lesion appeared on the hip and ear and was characterized by ballooning degeneration, necrosis of epithelial cells, and intranuclear inclusion bodies. The other was found on the ear and hematoma-like lesion was composed of fibrinoid exudation and degenerative connective tissue. PRV antigen was clearly demonstrated in both skin lesions. These results suggested that degeneration of myenteric plexuses might be another characteristic of lesions in PRV-infected pigs and that the virus spreads by interaction between the skin and myenteric plexuses to the central nervous system.