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Chronic intestinal pseudo-obstruction in a horse: A case of myenteric ganglionitis

Adenocarcinoma of the rectum annually affects more than 40 000 patients in the United States. HVEM acts as both a receptor for the canonical TNF-related ligands, LIGHT [lymphotoxin-like, exhibits inducible expression, and competes with herpes simplex virus glycoprotein D for HVEM, a receptor expressed on T lymphocytes] and lymphotoxin-α, and as a ligand for the immunoglobulin superfamily proteins BTLA (B and T lymphocyte attenuator) and CD160, a feature distinguishing HVEM from other immune regulatory molecules. In the present work, we studied the potential oncolytic activity of herpes simplex virus type 1 (HSV-1), using an organ culture system derived from colon carcinoma and healthy colon tissues of mouse and human origin. Because GSDMB is expressed in many types of cancer, including GC, it is likely that the gene contains a regulatory region that is utilized for therapy of occult PD through cancer cell-specific expression of cytotoxic genes. Pseudo-obstruction intestinale chronique chez une jument : un cas ganglionite myentérique. Une jument Quarter Horse âgée de 11 ans a été présentée pour coliques récurrentes. Furthermore, CEA-positive but not -negative tumor cells were rendered highly susceptible to ganciclovir when transfected with the EBV-based vector that carries the CEA promoter-EBNA1 and SRalpha-HSV-1 Tk genes (pTES.Tk).

Immunohistochemical staining of the tumors revealed a decreased number of blood vessels in the HSV-Endo-treated group versus the control group. L’examen histopathologique des tissus a révélé une ganglionite des plexus myentériques de l’intestin grêle et du colon ascendant. Chronic intestinal pseudo-obstruction (CIP) is a rare syndrome characterized by impaired intestinal peristalsis leading to clinical signs of obstruction (abdominal distension and bowel dilation, dysphagia, vomiting, constipation) in the absence of mechanical occlusion of the intestinal lumen (1,2). Histological examination revealed that the mucous layer became thinner in the proximal colon and increased number of lymphoid follicles in distal colon in infected animals. Four main etiopathogeneses underlie this syndrome: neuropathies, myopathies, secondary neuromuscular disorders and disorders of Cajal cells (2). Neural disorders appear to be far more common than other causes in human cases of CIP, some of which are characterized by a ganglionitis (2). In veterinary medicine, CIP is mostly associated with muscular disorders of the intestine (3–11).

Chronic intestinal pseudo-obstruction due to an intestinal ganglionitis is rare and has only been reported in a dog, a horse, and a cow (12–14). The previous reported equine case involved only the small colon and a mesenteric ganglion (13). We describe a case of CIP in a horse with myenteric ganglionitis of the small intestine and ascending colon. Duodenal biopsies showing typical KS features: spindle cell lesions with extravasated red blood cells that expand lamina propria (A: low power view; B: high power view (HE stain: A, ×40; B, ×400). Apart from gastric ulcers that were treated with cimetidine, there were no significant findings on physical examination, laboratory examinations, urinalysis, and abdominal palpation at its first presentation to our hospital. The laboratory investigations revealed hemoglobin-10.9 g/dl, total leucocytic count -4,200/μl, differential leucocytic count was lymphocytic predominant (54%), and a platelet count of 1.5 lakh/μl. Two years later, a second evaluation at our hospital revealed a severe and firm impaction of the large colon.

Additional diagnostic tests included a complete blood (cell) count (CBC), fecal flotation, serum biochemical analysis, fecal culture for Salmonella, abdominal ultrasonography, and abdominocentesis which revealed no abnormalities. The patient gave informed written consent to proceed with capsule endoscopy, with knowledge that PillCam retention was likely. Considering the history of recurrent colic and the poor response to medical treatment, surgical exploration was offered to the owners. Therefore, HVEM can be considered a molecular switch for various activating or inhibitory functions [18, 19]. After initial feeding, the impaction recurred; therefore, a complete pelleted diet was instituted. The mare was discharged with routine post-operative instructions and was fed a complete pelleted diet several times a day. One year later, the mare was readmitted to the Equine Hospital for recurrent episodes of colic, sometimes associated with large colonic impaction.

The initiating event might be an environmental insult, such as a viral infection, resulting in inflammation of the oesophageal myenteric plexus. A physical examination was performed but rectal palpation and other diagnostic procedures gave unremarkable results at the time of presentation. The mare underwent a second exploratory celiotomy which revealed no significant findings. In order to prevent the recurrent impactions noted clinically, a total resection of the left colon and a partial resection of the right colon were performed and right colonic anastomosis was carried out. Surgical biopsies of the ascending colon were submitted for histopathological examination. On sections of the diaphragmatic and pelvic flexures and left ventral colon, the myenteric plexuses were infiltrated by a small to moderate population of lymphocytes and rare macrophages, especially in the diaphragmatic flexure. Clinically, graft-versus-host disease ranged from exclusively lower gastrointestinal tract involvement to involvement of extracolonic sites, such as the skin, liver, and upper gastrointestinal tract.

Presumably, the HVEM receptor is responsible for LIGHT-mediated T cell activation, although that has not been formally proven. The effects of combination EGT were additive for the two genes. High magnification stains of CD68 or S-100 indicating positive histiocytes with emperipolesis of neutrophils. Myenteric plexus in the colon. To follow tumor development in the mouse and to quantitate the response to viral therapy, we stably transfected CT26 cells with the luciferase (luc) gene. However, LTα also forms a heteortrimer with the related cytokine, LTβ, which has a transmembrane domain, thus retaining LTα on the cell surface (21). I — inner muscular layer.

O — outer muscular layer. Hematoxylin-phloxin-eosin-saffron (HPES). Bar = 50 μm. … The post-operative period was normal until day 15, when the mare was presented with mild signs of abdominal pain. Rectal palpation revealed a moderate gas distension of the large colon. Laboratory findings were within the reference ranges and abdominal ultrasonography revealed no abnormalities.

Fasting for 48 h did not resolve the gas distension. A prokinetic treatment, cisapride (Prepulsid; Janssen Cilag, Belgium), 0.5 mg/kg body weight (BW) PO, q6h, and a corticoid, dexamethasone (Azium; Schering-Plough, Canada), 0.04 mg/kg BW, PO, q24h were instituted for 1 wk without improvement in the signs of abdominal pain. After discussion with the owners, they elected to have the horse euthanized and a complete necropsy was performed. No significant lesions were seen on gross examination of the animal. Tissues collected during postmortem were fixed in 10% neutral buffered formalin, routinely processed and stained with hematoxylin, phloxin, eosin, and saffron (HPES). A Masson’s Trichrome stain (MT) was also performed on gastrointestinal tissues. Sections of large colon examined displayed the same histomorphological changes as seen before on biopsy material.

LMP2A expression may lead to development of Hodgkin lymphoma (18). They were, however, more severe in the proximal jejunum and ileum. The mode of transmission for the various microsporidia remains obscure. Compared to an age- and sex-matched horse, there was a mild hyperplasia of both internal and external muscularis in some segments, as well as a mild, multifocal degeneration of the external muscular layer, characterized by vacuolation, atrophy, and nuclear pyknosis of individual myocytes (). There was no relation between the presence of ganglionitis and muscular degeneration. The MT stain enhanced visualization of this smooth muscle degeneration and did not reveal significant fibrosis of myenteric plexuses. In the stomach, rare myenteric plexuses located in the fundus were also infiltrated by several lymphocytes.


In the muscular layer of the esophagus, rare myocytes in the proximal half (striated muscle) were degenerate and necrotic, with phagocytosis of debris by macrophages and mild evidence of regeneration. There were no muscular lesions in the distal half of the esophagus (smooth muscle) and no involvement of myenteric plexuses in this organ. No significant changes were noted in extradigestive organs. Muscular layer in the small intestine. The binding of antibodies to Hu proteins on enteric neurons may promote the neurodegenerative processes underlying gut dysmotility. Note the normal myenteric plexus (arrow) close to the lesion. S — serosa, O — outer muscular layer, I — …

Polymerase chain reaction (PCR) testing was done on pooled formalin-fixed, paraffin-embedded sections of the colon and small intestine. Genomic DNA was extracted from the tissues and tested by nested-PCR for the amplification of 215 to 315 bp fragments of the herpesvirus DNA polymerase gene, which are common to many herpesviruses, including equine herpesvirus 1, 2 and 4. The PCR was negative. Thus, it would be unlikely that effects related to myeloablation would account for the constellation of clinical and pathological features. For verification of the inactivation of the HVEM gene, a Northern blot analysis of spleen RNA was performed using the cDNA encompassing the extracellular domain of the murine HVEM. To test the establishment of systemic anti-tumor immunity by our combination EGT, we rechallenged mice that were cured of CT26 tumors by combination EGT in experiment 6 by inoculating 1 105 CT26 cells into the contralateral flank. The etiology of this equine myenteric ganglionitis remains unknown.

In humans, myenteric ganglionitis is generally secondary to other pathologies (15). At day 13, animals were injected i.p. Furthermore, expression of CD160 was also detected in NKT cells (69). There was no evidence of a neoplastic process in this case. The development of autoantibodies against neurons has also been associated with Campylobacter sp. infection, as in the Guillain-Barré syndrome (2). In our case, a specific culture for Campylobacter was not performed.

But even if horses could harbor Campylobacter species in their intestinal flora, the presence of this bacterium has never been associated with inflammation or diarrhea in the equine species (1,16). Neurotrophic viruses, such as Herpesviridae (Herpes zoster, Epstein-Barr virus, and human cytomegalovirus), can directly damage myenteric plexuses in humans (2). An experimental infection of piglets with pseudorabies virus induced neuronal necrosis in submucosal and myenteric plexuses (17). In birds, proventricular dilatation disease (PDD) is a perfect example of myenteric ganglionitis for which a recently identified virus, Avian bornavirus, is thought to be a promising etiologic candidate (18). In our case, a panherpes PCR that normally detects not only equine herpesviruses 1, 2, and 4 but herpesviruses from many other mammals (including human herpesviruses) was performed. This PCR was negative. We can not exclude the possibility that this animal was infected by another herpes-virus not detected by this method, by a virus from a different family or even by an intact equine herpesvirus, for which DNA was under the threshold detection level of the test.

There was no fresh specimen available for PCR testing in this case and formalin-fixed, paraffin-embedded specimens are not the ideal samples for molecular testing (19). Long-term use of certain drugs, such as laxatives or opiates, has also been associated with ganglionitis in humans. It is unknown if they induce the inflammation or if they only mask an underlying problem inherent to myenteric plexuses (2). There was no recent history of such medication in our case and the association between a drug and gastrointestinal tract ganglionitis has never been reported in the veterinary literature. The histological features of GI KS are similar to cutaneous KS, which show spindle cells forming slit-like spaces containing red blood cells and pack the intestinal lamina propria. In humans, this disease generally affects young women and the pathogenesis is unclear but considered to be an immune-mediated reaction directed against neurons (2). No secondary cause has been identified in any animal case of myenteric ganglionitis published to date and all should therefore be classified as idiopathic (12–14,20).

In this case, the hyperplasia of the muscular layer in the small intestine is similar to the findings in the previously reported case of myenteric ganglionitis in a horse. In human idiopathic ganglionitis, the muscular layer could either become hyperplastic or atrophic; this change could be secondary to the neural damage (2,13). However, we have not been able to find any association between a myenteric ganglionitis and smooth muscle degeneration of the muscular layer in previous reports in either veterinary or human medical literature. It is not clear in our case if this myodegeneration was a significant contributing factor to the recurrent colic problem of this mare. This lesion could be secondary to the intestinal ganglionitis or be the result of a separate process. The latter hypothesis seems more likely as we observed myodegeneration in segments with no or only mild ganglionitis and, conversely, a normal muscular layer in segments with obvious inflammation of plexuses. In reports of pseudo-obstruction in small animals caused by intestinal myopathies or leiomyositis, there was no observed lesion in myenteric plexuses except in 2 cases.

In 1 case, a small number of neurons had chromatolysis and a few were shrunken, but the inflammation was not focused on ganglia (10). thrombosis and sepsis).137 In most cases, small bowel bacterial overgrowth is an important cause of diarrhoea and malnutrition, and it should be treated with antibiotic therapy. However, there was no inflammation in myenteric plexuses as in the present case. We considered the possibility of horse dysautonomia (equine grass sickness) unlikely even if autonomic ganglia were not observed, as dysautonomia is essentially a degenerative and not an inflammatory disease in horses (21). The treatment of intestinal pseudo-obstruction in humans includes dietary changes, prokinetic drugs such as cisapride, intestinal surgery (decompression, resection), and intestinal transplantation (2). In the veterinary literature, all but intestinal transplantation have been tried, generally combined with antibiotic therapy and supportive treatment such as metoclopramide and/or ranitidine. Except for intestinal resection in one case, all proved to be unsuccessful (3,5–8,11,22).

The predominance of autologous graft-versus-host disease in myeloma patients certainly deserves some attention, however. Samples were collected 4 or 5 wk after MLN transfer and subjected to H&E staining. When antigens are released from the tumor that has been destroyed by the HSV-tk gene therapy, simultaneous local expression of appropriate cytokines appears to enhance the anti-tumor immune response50,51. In one case, a cat with visceral myopathy recovered well following resection of a hypomotile section of the jejunum. The authors concluded that the favorable outcome could be attributed to rapid surgical intervention following the beginning of clinical signs (3). Treatment of tumors with HSV-G47Δ, without GCV, yielded efficient regression of the tumor and all treated animals survived past 21 days, whereas the control animals succumbed to the tumor by day 21 (Figures 5a and b). In naive human T cells, we estimated that HVEM and BTLA are expressed at approximately 1:1 ratio with >85% in cis-complex.

Veterinarians should include this entity in their differential diagnosis of recurrent colic of unknown origin in horses. The prognosis is generally poor. Use of this article is limited to a single copy for personal study. Anyone interested in obtaining reprints should contact the CVMA office (gro.vmca-amvc@nothguorbh) for additional copies or permission to use this material elsewhere. 1. Brown CC, Baker DC, Barker IK. Alimentary system.

In: Maxie GM, editor. Jubb, Kennedy & Palmer’s Pathology of Domestic Animals. 5th ed. Vol. 2. Toronto, Ontario: Elsevier; 2007. pp.

86–90.