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Gastrointestinal (GI) symptoms can originate from severe dysmotility due to enteric neuropathies. Current methods used to demonstrate enteric neuropathies are based mainly on classic qualitative histopathological/immunohistochemical evaluation. This study was designed to identify an objective morphometric method for paraffin-embedded tissue samples to quantify the interganglionic distance between neighboring myenteric ganglia immunoreactive for neuron-specific enolase, as well as the number of myenteric and submucosal neuronal cell bodies/ganglion in jejunal specimens of patients with severe GI dysmotility. Jejunal full-thickness biopsies were collected from 32 patients (22 females; 16-77 yr) with well-characterized severe dysmotility and 8 controls (4 females; 47-73 yr). A symptom questionnaire was filled before surgery. Mann-Whitney U test, Kruskal-Wallis coupled with Dunn's posttest and nonparametric linear regression tests were used for analyzing morphometric data and clinical correlations, respectively. Compared with controls, patients with severe dysmotility exhibited a significant increase in myenteric interganglionic distance ( P = 0.0005) along with a decrease in the number of myenteric ( P < 0.00001) and submucosal ( P < 0.0004) neurons. A 50% reduction in the number of submucosal and myenteric neurons correlated with an increased interganglionic distance and severity of dysmotility. Our study proposes a relatively simple tool that can be applied for quantitative evaluation of paraffin sections from patients with severe dysmotility. The finding of an increased interganglionic distance may aid diagnosis and limit the direct quantitative analysis of neurons per ganglion in patients with an interganglionic distance within the control range. NEW & NOTEWORTHY Enteric neuropathies are challenging conditions characterized by a severe impairment of gut physiology, including motility. An accurate, unambiguous assessment of enteric neurons provided by quantitative analysis of routine paraffin sections may help to define neuropathy-related gut dysmotility. We showed that patients with severe gut dysmotility exhibited an increased interganglionic distance associated with a decreased number of myenteric and submucosal neurons, which correlated with symptoms and clinical manifestations of deranged intestinal motility.

Background: Chronic intestinal pseudo-obstruction (CIPO) and enteric dysmotility (ED) are severe intestinal motility disorders usually associated with underlying neuromuscular abnormalities., Objective: To evaluate the in vitro neuromuscular function of patients with severe intestinal motility disorders., Methods: Full-thickness intestinal biopsies (16 jejunum and 3 ileum) obtained from patients with CIPO (n = 10) and ED (n = 9) were studied using muscle bath and microelectrode techniques. Control samples (n = 6 ileum and n = 6 jejunum) were used to establish the range of normality., Key Results: Fourteen parameters were defined to assess muscle contractility and nerve-muscle interaction: five to evaluate smooth muscle and interstitial cells of Cajal (ICC) and nine to evaluate inhibitory neuromuscular transmission. For each sample, a parameter was scored 0 if the value was inside the normal range or a value of 1 if it was outside. Patients' samples (CIPO/ED) had more abnormal parameters than controls (P < 0.001 for both jejunum and ileum). Functional abnormalities were found to be heterogeneous. The most prevalent abnormality was a decreased purinergic neuromuscular transmission, which was detected in 43.8% of jejunal samples., Conclusions and Inferences: Abnormalities of neuromuscular intestinal function are detected in vitro in severe intestinal dysmotility. However, consistent with the heterogeneity of the disease pathophysiology, functional impairment cannot be attributed to a single mechanism. Specifically, defects of purinergic neuromuscular transmission may have an important role in motility disorders of the gastrointestinal tract., (© 2018 John Wiley & Sons Ltd.)

Background & Aims: Chronic intestinal pseudo-obstruction (CIPO) is characterized by severe intestinal dysmotility that mimics a mechanical subocclusion with no evidence of gut obstruction. We searched for genetic variants associated with CIPO to increase our understanding of its pathogenesis and to identify potential biomarkers., Methods: We performed whole-exome sequencing of genomic DNA from patients with familial CIPO syndrome. Blood and lymphoblastoid cells were collected from patients and controls (individuals without CIPO); levels of messenger RNA (mRNA) and proteins were analyzed by quantitative reverse-transcription polymerase chain reaction, immunoblot, and mobility shift assays. Complementary DNAs were transfected into HEK293 cells. Expression of rad21 was suppressed in zebrafish embryos using a splice-blocking morpholino (rad21a). Gut tissues were collected and analyzed., Results: We identified a homozygous mutation (p.622, encodes Ala>Thr) in RAD21 in patients from a consanguineous family with CIPO. Expression of RUNX1, a target of RAD21, was reduced in cells from patients with CIPO compared with controls. In zebrafish, suppression of rad21a reduced expression of runx1; this phenotype was corrected by injection of human RAD21 mRNA, but not with the mRNA from the mutated p.622 allele. rad21a Morpholino zebrafish had delayed intestinal transit and greatly reduced numbers of enteric neurons, similar to patients with CIPO. This defect was greater in zebrafish with suppressed expression of ret and rad21, indicating their interaction in the regulation of gut neurogenesis. The promoter region of APOB bound RAD21 but not RAD21 p.622 Ala>Thr; expression of wild-type RAD21 in HEK293 cells repressed expression of APOB, compared with control vector. The gut-specific isoform of APOB (APOB48) is overexpressed in sera from patients with CIPO who carry the RAD21 mutation. APOB48 also is overexpressed in sporadic CIPO in sera and gut biopsy specimens., Conclusions: Some patients with CIPO carry mutations in RAD21 that disrupt the ability of its product to regulate genes such as RUNX1 and APOB. Reduced expression of rad21 in zebrafish, and dysregulation of these target genes, disrupts intestinal transit and the development of enteric neurons., (Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.)

The pathogenetic mechanisms underlying gastrointestinal dysmotility in diabetic patients remain poorly understood, although enteric neuropathy, damage to interstitial cells of Cajal (ICC) and smooth muscle cell injury are believed to play a role. The aim of this study was to investigate the morphological and functional changes underlying intestinal dysmotility in RIP-I/hIFNβ transgenic mice treated with multiple very low doses of streptozotocin (20 mg/kg, i.p., 5 days). Compared with vehicle-treated mice, streptozotocin-treated animals developed type 1 diabetes mellitus, with sustained hyperglycaemia for 3.5 months, polyphagia, polydipsia and increased faecal output without changes in faecal water content (metabolic cages). Diabetic mice had a longer intestine, longer ileal villi and wider colonic crypts (conventional microscopy) and displayed faster gastric emptying and intestinal transit. Contractility studies showed selective impaired neurotransmission in the ileum and mid-colon of diabetic mice. Compared with controls, the ileal and colonic myenteric plexus of diabetic mice revealed ultrastructural features of neuronal degeneration and HuD immunohistochemistry on whole-mount preparations showed 15% reduction in neuronal numbers. However, no immunohistochemical changes in apoptosis-related markers were noted. Lower absolute numbers of neuronal nitric oxide synthase- and choline acetyltransferase-immunopositive neurons and enhanced vasoactive intestinal polypeptide and substance P immunopositivity were observed. Ultrastructural and immunohistochemical analyses did not reveal changes in the enteric glial or ICC networks. In conclusion, this model of diabetic enteropathy shows enhanced intestinal transit associated with intestinal remodelling, including neuroplastic changes, and overt myenteric neuropathy. Such abnormalities are likely to reflect neuroadaptive and neuropathological changes occurring in this diabetic model., (© 2011 The Authors. International Journal of Experimental Pathology © 2011 International Journal of Experimental Pathology.)