Roberto Corinaldesi

A role for inflammation in irritable bowel syndrome

Attention has been directed to the putative role of low grade mucosal inflammation in irritable bowel syndrome (IBS) on the basis of evidence showing that some patients with IBS have an increased number of inflammatory cells in the colonic and ileal mucosa. Previous episodes of infectious enteritis, genetic factors, undiagnosed food allergies, and changes in bacterial microflora may all play a role in promoting and perpetuating this low grade inflammatory process. Human and animal studies support the concept that inflammation may perturb gastrointestinal reflexes and activate the visceral sensory system even when the inflammatory response is minimal and confined to the mucosa. Thus abnormal neuroimmune interactions may contribute to the altered gastrointestinal physiology and hypersensitivity that underlies IBS. A brief review of the human and animal studies that have focused on the putative role of intestinal inflammation and infections in the pathogenesis of IBS is given.

Mucosal Immune Activation in Irritable Bowel Syndrome: Gender-Dependence and Association With Digestive Symptoms

OBJECTIVES:Immune activation may be involved in the pathogenesis of irritable bowel syndrome (IBS). However, the relative magnitude of this immune component and its correlation with gender and gastrointestinal complaints in IBS patients remains poorly elucidated.METHODS:We enrolled 48 IBS patients, with either diarrhea or constipation, 12 patients with microscopic colitis, 20 patients with ulcerative colitis, and 24 healthy controls. Colonic immunocytes were identified with quantitative immunohistochemistry on mucosal biopsies. Gastrointestinal symptoms were assessed using a validated questionnaire.RESULTS:IBS patients showed a significant 72% increase in mucosal immune cells compared to controls (P<0.001). Further analyses showed that increased immune cells were present in 50% of the IBS patients. The magnitude of the immune infiltrate in IBS was significantly lower than that of microscopic colitis or ulcerative colitis (42% and 124% increases vs. IBS, respectively; P<0.001). Compared with controls, IBS patients had increased numbers of CD3+, CD4+, and CD8+ T cells and mast cells (P<0.001). Compared to male IBS patients, female IBS patients had greater numbers of mast cells (P=0.066), but lower numbers of CD3+ and CD8+ T cells (P=0.002 and <0.001, respectively). Mucosal mast cell infiltration of IBS patients was significantly associated with abdominal bloating frequency (P=0.022) and with symptoms of dysmotility-like dyspepsia (P=0.001), but not ulcer-like dyspepsia.CONCLUSIONS:A large subset of IBS patients shows gender-dependent mucosal infiltration of immunocytes that correlates with abdominal bloating and dysmotility-like dyspepsia. These results provide the rationale for considering immune mechanisms as a pathophysiological component in a subset of IBS patients.

Fat-induced heal brake in humans: A dose-dependent phenomenon correlated to the plasma levels of peptide YY

BACKGROUND Upper gastrointestinal motility is regulated by the presence of nutrients in the distal gut. The present study evaluated whether lipid-induced ileal brake on gastric emptying (1) can be elicited by low fat concentrations; (2) is a dose-dependent phenomenon; and (3) is related to gastrointestinal peptide release. METHODS Seven patients were studied in the defunctionalized stage of total colectomy, on three separate occasions. On each study day, patients ate a meal labeled in the solid component; 30 minutes later, one of the following solutions was randomly infused into the ileal pouch: 0.9% saline, 2% oleic acid, and 20% oleic acid. Plasma concentrations of peptide YY (PYY), enteroglucagon, neurotensin, and motilin were measured. RESULTS Both oleic acid solutions slowed gastric emptying compared with saline (P < 0.001), the effect being dose dependent (P < 0.001). Ileal infusions did not modify neurotensin and enteroglucagon levels but induced a dose-dependent increase of PYY (P < 0.01) and a borderline decrease of motilin (P = 0.05) levels. Slower rates of gastric emptying were related to increased plasma concentrations of PYY (r = 0.615; P < 0.05). CONCLUSIONS This study shows that (1) the ileal brake on gastric emptying can be evoked by low doses of lipids in the distal ileum; (2) the delay of gastric emptying is related to the release of PYY; and (3) both phenomena are dose dependent.

Helicobacter pylori infection and gastric function in patients with chronic idiopathic dyspepsia

Helicobacter pylori infection, histological features of the gastric mucosa, and gastric motor and secretory functions were evaluated in 45 consecutive patients with chronic idiopathic dyspepsia. H. pylori infection was found in 60% of dyspeptic patients, compared with 33% of 15 healthy controls (P = 0.1). No difference was detected in basal or stimulated gastric acid secretion between dyspeptic patients and healthy controls. Gastric emptying was significantly (P less than 0.01) delayed in dyspeptic patients compared with healthy controls when standardized for age and sex. Delayed gastric emptying was associated with a low frequency of H. pylori infection, female gender, and young age. Epigastric pain or burning and postprandial fullness were, respectively, more severe in patients with H. pylori infection (P less than 0.02) and in those with delayed gastric emptying (P less than 0.01). These findings support the existence of separate subsets of patients with chronic idiopathic dyspepsia. Despite the presence of overlaps, there appear to be partially different functional derangements and clinical features in different subgroups of dyspeptic patients.

New pathophysiological mechanisms in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional, multifactorial disease characterized by abdominal pain and erratic bowel habit. Changes in gastrointestinal motor function, enhanced perception of stimuli arising from the gut wall and psychosocial factors are thought to be major contributors for symptom generation. In recent years, several additional factors have been identified and postulated to interact with these classical mechanisms. Reduced ability to expel intestinal gas with consequent gas trapping and bowel distension may contribute to abdominal discomfort/pain and bloating. Abnormal activation of certain brain regions following painful stimulation of the rectum suggests altered processing of afferent signals. An acute gastrointestinal infection is now a recognized aetiological factor for symptom development in a subset of IBS patients (i.e. post‐infectious IBS), who are probably unable to down‐regulate the initial inflammatory stimulus efficiently. Furthermore, low‐grade inflammatory infiltration and activation of mast cells in proximity to nerves in the colonic mucosa may also participate in the frequency and severity of perceived abdominal pain in post‐infectious and non‐specific IBS. Initial evidence suggests the existence of changes in gut microflora, serotonin metabolism and a genetic contribution in IBS pathophysiology. These novel mechanisms may aid a better understanding of the complex pathophysiology of IBS and to develop new therapies.

Interactions between commensal bacteria and gut sensorimotor function in health and disease.

Commensal bacteria inhabiting the human intestine (i.e., intestinal microflora) participate in the development and maintenance of gut sensory and motor functions, including the promotion of intestinal propulsive activity. On the other hand, intestinal motility represents one of the major control systems of gut microflora, through the sweeping of excessive bacteria from the lumen. There is emerging evidence indicating that changes in this bidirectional interplay contribute to the pathogenesis of gut diseases, such as small intestinal bacterial overgrowth and intestinal pseudo-obstruction. Recent interest has also been directed to the potential role of intestinal microflora in the pathogenesis of the irritable bowel syndrome. Although the status of intestinal microflora in the irritable bowel syndrome remains unsettled, small intestinal bacterial overgrowth (as detected with breath testing) and increased fermentation of foods with gas production, provide indirect evidence that microflora may contribute to symptom generation in irritable bowel syndrome. The potential benefit of antibiotic and probiotic therapy is currently under investigation and opens new perspectives in irritable bowel syndrome treatment.

Advances in our understanding of the pathology of chronic intestinal pseudo-obstruction

Chronic intestinal pseudo-obstruction (CIP) represents a particularly difficult clinical challenge. It is a rare and highly morbid syndrome characterised by impaired gastrointestinal propulsion together with symptoms and signs of bowel obstruction in the absence of any lesions occluding the gut lumen. CIP can be classified as either “secondary” to a wide array of recognised pathological conditions or “idiopathic” (CIIP). This review will focus on CIIP, and specifically on the underlying pathological abnormalities. Combined clinical and histopathological studies are needed to highlight new perspectives in the understanding and management of chronic intestinal pseudo-obstruction.

Chromogranin A: Is It a Useful Marker of Neuroendocrine Tumors?

PURPOSE We evaluated the pattern of chromogranin A (CgA) plasma levels in a large number of patients with neuroendocrine tumors (NETs), in a series of patients with chronic atrophic gastritis (CAG) with and without enterochromaffin-like (ECL) cell hyperplasia, and in healthy participants (HPs). PATIENTS AND METHODS Two hundred thirty-eight patients with NETs, 42 patients with CAG with or without ECL cell hyperplasia, and 48 HPs were studied. All patients underwent a baseline visit, biochemical routine check-up, imaging techniques, endoscopy, and histologic determination. RESULTS CgA plasma levels were higher in patients with NETs compared with CAG patients or HPs (P < .001). In the NET group, we observed higher CgA levels in patients with diffuse disease compared with patients with local or hepatic disease (P < .001). CgA plasma levels were significantly higher in patients with Zollinger-Ellison syndrome compared with other types of endocrine tumors (P < .001). We found the best cutoff range between HPs and NET patients to be 18 to 19 U/L (sensitivity, 85.3%; specificity, 95.8%). Comparing all participants without neoplasia (HPs, CAG patients, and disease-free patients) and patients with endocrine tumors, the best cutoff range was 31 to 32 U/L (sensitivity, 75.3%; specificity, 84.2%). Setting the specificity at 95%, the cutoff range was 84 to 87 U/L (sensitivity, 55%). CONCLUSION Our study confirms the high specificity and sensitivity of CgA in diagnosing an endocrine tumor. It is necessary to use a cutoff range of 84 to 87 U/L to obtain a high specificity in diagnosing NETs, with the aim of excluding patients in whom the CgA was elevated as a result of other non-neoplastic diseases.

Effect of chronic administration of cisapride on gastric emptying of a solid meal and on dyspeptic symptoms in patients with idiopathic gastroparesis.

In a double blind crossover comparison with placebo, the effects of cisapride (10 mg tid for two weeks), a non-antidopaminergic gastrointestinal prokinetic drug, on gastric emptying times and on symptoms were evaluated in 12 patients with chronic idiopathic dyspepsia and gastroparesis. Gastric emptying was studied by a radioisotopic gamma camera technique. The test meal was labelled in the solid component (99mTc-sulphur colloid infiltrated chicken liver). Nine symptoms (nausea, belching, regurgitations, vomiting, postprandial drowsiness, early satiety, epigastric pain or burning, heartburn) were graded weekly on a questionnaire. Cisapride was significantly more effective than placebo in shortening the t1/2 of gastric emptying (p2 = 0.04), but no significant difference was observed between the two treatments with regard to the improvement of total symptom score (p2 = 0.09). No side effects were reported during the study.

Enteric neuroplasticity evoked by inflammation

Neuroplastic changes in the enteric nervous system (ENS) may be observed in physiological states, such as development and aging, or occur as a consequence of different pathological conditions, ranging from enteric neuropathies (e.g., Hirschsprungs disease) to intestinal (e.g., inflammatory bowel disease) or extra-intestinal diseases (e.g., Parkinsons disease). Studying ENS plasticity may help to elucidate the pathophysiology of several diseases and have a bearing on the development of new pharmacological interventions. In the present review, we would like to focus on neuronal plasticity evoked by gastrointestinal inflammation occurring in inflammatory bowel disease and in a subset of patients with severe derangement of gut motility due to an enteric neuropathy characterized by an inflammatory infiltrate of the enteric plexuses. Major features of neuroplasticity within the enteric microenvironment encompass structural abnormalities ranging from nerve re-arrangement (e.g., hypertrophy and hyperplasia) to degeneration and loss of enteric ganglion cells; altered synthesis, content and release of neurotransmitters as well as up- or down-regulation of receptor systems; gastrointestinal dysfunction characterized by sensory-motor and secretory impairment of the gut. Interestingly, neuronal changes may also occur in segments of the gastrointestinal tract remote from the site of the original inflammation, e.g. the ileum may show neuroplastic changes during colitis. Sometimes, the inflamed site may even be outside the gut. Among potential mechanisms underlying ENS plasticity, neurotrophins and enteric glia deserve special attention. A better comprehension of ENS plasticity during inflammation could be instrumental to develop new therapeutic options for patients with IBD and inflammatory enteric neuropathies.