ABSTRACT
This study investigated whether toxin B of Clostridium difficile can activate human submucosal neurons and the involved pathways. Isolated segments of human colon were placed in organ culture for 3 h in the presence of toxin B or IL-1beta. Whole mounts of internal submucosal plexus were stained with antibodies against c-Fos, neuron-specific enolase (NSE), vasoactive intestinal polypeptide (VIP), and substance P (SP). The membrane potential (Vm) response of submucosal neurons to local application of toxin B and IL-1beta was determined by a multisite optical recording technique. Toxin B (0.1 to 10 ng/ml) increased the proportion of c-Fos-positive neurons dose dependently compared with the control. In the presence of toxin B (10 ng/ml), most c-Fos-positive neurons were immunoreactive for VIP (79.8 +/- 22.5%) but only 19.4 +/- 14.0% for SP. Toxin B induced a rapid rise in IL-1beta mRNA level and a sixfold increase in IL-1beta protein in supernatant after 3 h of incubation. c-Fos expression induced by toxin B was reduced dose dependently by IL-1 receptor antagonist (0.1-10 ng/ml). IL-1beta significantly increased c-Fos expression in submucosal neurons compared with the control (34.2 +/- 10.1 vs. 5.1 +/- 1.3% of NSE neurons). Microejection of toxin B had no effect on the Vm of enteric neurons. Evidence of a direct excitatory effect of IL-1beta on Vm was detected in a minority of enteric neurons. Therefore, toxin B of C. difficile activates VIP-positive submucosal neurons, at least in part, via an indirect IL-1beta-dependent pathway.
Subject(s)
Bacterial Proteins , Bacterial Toxins/pharmacology , Colon/innervation , Interleukin-1/physiology , Neurons/physiology , Submucous Plexus/physiology , Vasoactive Intestinal Peptide/metabolism , Aged , Humans , Immunohistochemistry , In Vitro Techniques , Interleukin-1/pharmacology , Membrane Potentials/drug effects , Neurons/drug effects , Neurons/metabolism , Proto-Oncogene Proteins c-fos/metabolism , Submucous Plexus/cytology , Submucous Plexus/drug effects , Submucous Plexus/metabolismABSTRACT
BACKGROUND: Morphological and functional changes in the enteric nervous system (ENS) have been reported in inflammatory bowel diseases but it is still uncertain whether neurochemical coding of myenteric neurones is altered in ulcerative colitis (UC). AIMS: In this study we investigated transmitter co-localisation in myenteric neurones of normal colon and the colon of patients with UC. METHODS: Choline acetyltransferase (ChAT), neurone specific enolase (NSE), vasoactive intestinal peptide (VIP), and substance P (SP) were detected by immunohistochemical methods in whole mounts of colonic myenteric plexus of UC patients (n=10) and controls (n=8). RESULTS: The proportion of ChAT positive and VIP positive neurones relative to the NSE population did not differ in inflamed (33.3% and 9.3%, respectively) and non-inflamed segments (33.6% and 9.7%) of UC colon compared with controls (35.0% and 6.9%). The proportion of SP positive neurones was significantly larger in both inflamed (15.5%) and non-inflamed (20.3%) segments than in controls (5.9%). Analysis of changes in subpopulations showed that 26.9% of neurones were only ChAT positive in controls but that the proportion was significantly smaller in inflamed (18.8%) and non-inflamed (15.8%) areas of UC. The proportions of neurones containing ChAT and SP were significantly higher in inflamed (11.8%) and non-inflamed (13.9%) areas than in controls (5.0%). CONCLUSION: Remodelling of myenteric neurones in UC involves a shift from mainly cholinergic to more SP positive innervation. This effect may constitute part of the neuronal basis for the motility disturbances observed in UC.
Subject(s)
Colitis, Ulcerative/metabolism , Colon/innervation , Muscle, Smooth/innervation , Myenteric Plexus/metabolism , Neurons/chemistry , Neurotransmitter Agents/analysis , Adult , Aged , Aged, 80 and over , Analysis of Variance , Case-Control Studies , Choline O-Acetyltransferase/analysis , Choline O-Acetyltransferase/metabolism , Colitis, Ulcerative/physiopathology , Female , Gastrointestinal Motility , Humans , Immunohistochemistry/methods , Male , Middle Aged , Neurons/metabolism , Phosphopyruvate Hydratase/analysis , Phosphopyruvate Hydratase/metabolism , Substance P/analysis , Substance P/metabolism , Vasoactive Intestinal Peptide/analysis , Vasoactive Intestinal Peptide/metabolismABSTRACT
OBJECTIVE: To better characterize the presentation of gangrenous and non-gangrenous ischemic colitis in subjects older than 60 years, and to identify risk factors of gangrenous outcome. METHODS: Retrospective analysis of 80 cases of ischemic colitis (22 male, 58 female; mean age 76.9 +/- 8.7 years) with 64 and 16 non gangrenous and gangrenous forms, respectively. RESULTS: Hematochezia and diarrhea were significantly less prevalent in gangrenous colitis compared to the non-gangrenous group (31.2% vs 81.2%, P < 0.0001 and 6.2% vs 53.1%, P < 0.0001, respectively), whereas nausea and vomiting, and hyperleukcocytosis were significantly more frequent in the former group (50.0% vs 18.7%, P < 0.01 and 93.7% vs 62.5%, P < 0.02 respectively). Hypertension (P < 0.03), angina (P < 0.05), history of cancer (P < 0.03) and age older than 90 (P < 0.002) were risk factors for gangrenous outcome. After multivariate analysis, only two independent factors were identified, i.e.: hypertension and history of cancer. These factors predicted gangrenous course in 85% of cases. CONCLUSION: Patients older than 60 years suffering from ischemic colitis are at high risk of gangrenous course if they have hypertension or history of cancer.
