Instability of the faecal microbiota in diarrhoea-predominant irritable bowel syndrome

Abstract

The irritable bowel syndrome (IBS) is a functional gastrointestinal disorder with a largely unknown aetiology and a wide range of symptoms. Most cross-sectional studies carried out so far suggest subtle alterations in the structure of the intestinal microbiota that are barely reproduced, partly because of the high inter-subject variation in the community composition and disorder-specific features. We performed a longitudinal study to explore the within-subject variation in the faecal microbiota in two patients with IBS classified into the diarrhoea subtype and the healthy spouse of one of them. Faecal communities were monitored over 6-8 weeks and analysed through metagenomic and metatranscriptomic approaches. We found a higher temporal instability in the fraction of active microbiota related to the IBS condition and fluctuating symptoms. Strong and quick shifts in the distribution of the active microbiota and changes in the global pattern of gene expression were detected in association with acute diarrhoea, whereas microbial composition and encoded functions were more stable. The specific alterations in the microbiota were barely reproduced within and between patients. Further research is needed to assess whether these changes are a consequence of the abnormal gut function in acute diarrhoeic episodes and the potential usefulness of tackling them.

Health and disease imprinted in the time variability of the human microbiome

“…Second, the scaling index was always smaller than 1, which means that the more abundant taxa were less volatile than the less abundant ones. In addition, Taylor's parameters for the microbiome of healthy subjects in different studies (12,(48)(49)(50)(51)(52)(53) were compatible with estimated errors. This enabled us to define an area in the Taylor parameter space that we called the healthy zone.…”

“…To jointly visualize and compare the results of subjects from the above-mentioned studies (12,(48)(49)(50)(51)(52)(53), their Taylor parameters were standardized, with standardization meaning that the mean value was subtracted from each parameter and the result was divided by the standard deviation of the group of healthy subjects for every study independently. Because of the different systematics in each study, we defined a healthy region for each of them, standardized to a mean of 0 and a variance of 1, then we computed the mean and variance of the "unhealthy" with this standardization (for details of the procedure, see the standardization subsection in Materials and Methods).…”

“…Research has revealed that the human microbiome is intimately linked to our physiology through the metabolism of bile acids (4), choline (5), and key metabolites such as short-chain fatty acids (6,7), which are also involved in immune system maturation (8,9). The human microbiota is plausibly related to diseases such as type 2 diabetes (10), cardiovascular disease (11), irritable bowel syndrome (IBS) (12), and Crohn's disease (13) and some afflictions like obesity (14,15) and malnutrition (16), as well as many other diseases (17). Current studies have revealed that gut microbes also influence brain function and behavior and are related to neurological disorders like Alzheimer's disease through the gut-brain axis (18,19).…”

New and emerging therapies for the treatment of irritable bowel syndrome: an update for gastroenterologists

“…The gut microbiota of patients with IBS differs qualitatively and quantitatively compared with that of healthy individuals [Carroll et al 2011;Codling et al 2010;Durbán et al 2012Durbán et al , 2013. Symptoms of IBS have been associated with specific gut microbiota profiles [Jeffery et al 2012].…”

Modulation of the gut microbiota: a focus on treatments for irritable bowel syndrome

“…small intestinal bacterial overgrowth [SIBO]) [21,23]. The gut microbiota appears to play an important role in IBS (Figure 1), as quantitative and qualitative differences have been observed in patients with IBS compared with healthy individuals [24][25][26][27][28][29]. For instance, a greater magnitude of gut microbiota instability has been associated with greater intensity of symptoms in some patients with IBS [24].…”