Irritable bowel syndrome: Emerging paradigm in pathophysiology

Abstract

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders, characterized by abdominal pain, bloating, and changes in bowel habits. These symptoms cannot be explained by structural abnormalities and there is no specific laboratory test or biomarker for IBS. Therefore, IBS is classified as a functional disorder with diagnosis dependent on the history taking about manifested symptoms and careful physical examination. Although a great deal of research has been carried out in this area, the pathophysiology of IBS is complex and not completely understood. Multiple factors are thought to contribute to the symptoms in IBS patients; altered gastrointestinal motility, visceral hypersensitivity, and the brain-gut interaction are important classical concepts in IBS pathophysiology. New areas of research in this arena include inflammation, postinfectious low-grade inflammation, genetic and immunologic factors, an altered microbiota, dietary factors, and enteroendocrine cells. These emerging studies have not shown consistent results, provoking controversy in the IBS field. However, certain lines of evidence suggest that these mechanisms are important at least a subset of IBS patients, confirming that IBS symptoms cannot be explained by a single etiological mechanism. Therefore, it is important to keep in mind that IBS requires a more holistic approach to determining effective treatment and understanding the underlying mechanisms.

Antibiotic-induced dysbiosis alters host-bacterial interactions and leads to colonic sensory and motor changes in mice

“…1 Although still partially unknown, IBS has a multifactorial pathogenesis involving psychosocial factors (such as stress), an intestinal immune activation (with a persistent low grade inflammation) and altered brain-gut-brain communication and host-microbial interactions. [1][2][3][4] Within the intestine, microbial community is established shortly from birth and acts as an entire organ. 5,6 Recent works have identified gut commensal microbiota (GCM) as a dynamic ecosystem that maintains a bidirectional relationship with the host and that is essential for physiological and pathophysiological states.…”

Intravenous Corticotropin-releasing Hormone Administration Increases Esophageal Electrical Sensitivity in Healthy Individuals

“…6 Central and gastrointestinal responses to stress can be pronounced, particularly in patients with FGID such as IBS. 7,8,15,16 The association between stress and visceral perception has been reported in a number of colonic studies. Fukudo et al 17 showed…”

Parasitosis y síndrome de intestino irritable

“…Dentro de los mecanismos biológicos alterados se incluyen: la activación de células inmunes en la mucosa intestinal, tales como linfocitos T, linfocitos B y mastocitos; las alteraciones en la composición y aumento del número de la microbiota intestinal, que llevan al procesamiento anormal de moléculas presentes en la dieta; y la mayor liberación de sustancias bioactivas por células enterocromafines (EC) 11,14,16,17 . La respuesta inflamatoria intestinal es reforzada por una mayor actividad nerviosa entérica, relacionada al aumento de la sensibilidad visceral e incremento en la estimulación de terminales nerviosos aferentes y a la alteración del eje intestino-cerebro en estos pacientes 18 .…”

“…mucosa, muchos de ellos provenientes de la dieta y de la microbiota. La estimulación aumentada del sistema inmune local trae como consecuencia el aumento en la liberación de mediadores inflamatorios y el reclutamiento de mayores componentes celulares a la mucosa intestinal, perpetuando de esta manera el ciclo de inflamación cró-nica 11,23 . Se ha demostrado que la respuesta inmune local www.sochinf.cl…”