Research.
Source: mdpi.com/2076-2607/11/10/2369
Abstract
"Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder characterized by chronic abdominal pain and altered bowel habits. It can be subclassified in different subtypes according to the main clinical manifestation: constipation, diarrhea, mixed, and unclassified. Over the past decade, the role of gut microbiota in IBS has garnered significant attention in the scientific community. Emerging research spotlights the intricate involvement of microbiota dysbiosis in IBS pathogenesis. Studies have demonstrated reduced microbial diversity and stability and specific microbial alterations for each disease subgroup. Microbiota-targeted treatments, such as antibiotics, probiotics, prebiotics, synbiotics, fecal microbiota transplantation, and even diet, offer exciting prospects for managing IBS. However, definitive conclusions are hindered by the heterogeneity of these studies. Further research should focus on elucidating the mechanisms, developing microbiome-based diagnostics, and enabling personalized therapies tailored to an individual’s microbiome profile. This review takes a deep dive into the microscopic world inhabiting our guts, and its implications for IBS. Our aim is to elucidate the complex interplay between gut microbiota and each IBS subtype, exploring novel microbiota-targeted treatments and providing a comprehensive overview of the current state of knowledge."
Keywords:
irritable bowel syndrome; IBS; microbiota; microflora; gut; subtype IBS-D; subtype IBS-C
"1. Introduction
Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder characterized by abdominal pain and altered bowel habits, either in stool form or frequency, persisting for at least 6 months in the absence of an identifiable organic pathology [1].
According to the Rome IV criteria, IBS can be subclassified into four types, diarrhea-predominant IBS (IBS-D), constipation-predominant IBS (IBS-C), mixed IBS (IBS-M), and unclassified IBS (IBS-U), based on the main clinical presentation [2].
It is challenging to ascertain precisely the global prevalence of IBS due to the lack of diagnostic biomarkers detectable in blood or stools, but current estimates suggest it affects approximately 5–10% of the population, in most countries [3]. The prevalence of IBS is higher in women compared to men [4]. It impacts individuals across all age groups, with symptom onset prior to 35 years for 50% of patients and a decreasing prevalence in patients over the age of 50 years [2]. Risk factors include a younger age, prior gastrointestinal infections, and stressful events, among others [5,6,7] (Figure 1).
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Figure 1. Main risk factors in irritable bowel syndrome (IBS).
The pathophysiologic mechanisms underlying IBS remain unclear. Numerous pathogenic factors have been proposed, including alterations in gastrointestinal motility, visceral hypersensitivity, gut–brain axis dysfunction, low-grade intestinal inflammation and impaired epithelial barrier integrity [8,9,10]. IBS is often observed with other gastrointestinal and extraintestinal pathologies, as this syndrome has been connected especially to functional dyspepsia and gastroesophageal reflux disease, but also to fibromyalgia, chronic fatigue syndrome, chronic pain, and psychiatric conditions [11,12,13,14,15,16,17,18,19,20].
Emerging data suggest that gut microbiota dysbiosis may also contribute to disease development, even if plenty of evidence exhibited significant divergence due to heterogeneity, failing to delineate any uniform characteristic of the IBS-related microbiome, despite significant technological improvement over the past few years [11,21,22].
The commensal gut microbiota represents the largest symbiotic ecosystem in humans, exerting profound effects on health and disease, modulating biological processes [23]. It is also known to play a significant role in the pathogenesis of various gastroenterological diseases [24,25,26,27]. Growing evidence indicates a significant role for gut dysbiosis in IBS development, although specific microbial compositional changes and mechanisms remain to be fully elucidated [26]. Bidirectional relationships likely exist between dysbiosis and pathophysiological disturbances in IBS, and microbiome alterations may arise from and/or contribute to abnormalities in its pathogenesis [28].
This narrative review aims to provide a concise overview of the most recent evidence and developments regarding the role of the microbiota and its composition for the different IBS subtypes, comparing them to each other. We also explored the implications that these differences can bring to clinical practice by addressing microbiota-targeted treatment options for each disease subgroup."
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