Jonna Jalanka

Intestinal Microbiota And Diet in IBS: Causes, Consequences, or Epiphenomena?

Irritable bowel syndrome (IBS) is a heterogeneous functional disorder with a multifactorial etiology that involves the interplay of both host and environmental factors. Among environmental factors relevant for IBS etiology, the diet stands out given that the majority of IBS patients report their symptoms to be triggered by meals or specific foods. The diet provides substrates for microbial fermentation, and, as the composition of the intestinal microbiota is disturbed in IBS patients, the link between diet, microbiota composition, and microbial fermentation products might have an essential role in IBS etiology. In this review, we summarize current evidence regarding the impact of diet and the intestinal microbiota on IBS symptoms, as well as the reported interactions between diet and the microbiota composition. On the basis of the existing data, we suggest pathways (mechanisms) by which diet components, via the microbial fermentation, could trigger IBS symptoms. Finally, this review provides recommendations for future studies that would enable elucidation of the role of diet and microbiota and how these factors may be (inter)related in the pathophysiology of IBS.

Effects of bowel cleansing on the intestinal microbiota

Objective An adequate bowel cleansing is essential for a successful colonoscopy. Although purgative consumption is safe for the patient, there is little consensus on how the intestinal microbiota is affected by the procedure, especially regarding the potential long-term consequences. Design 23 healthy subjects were randomised into two study groups consuming a bowel preparation (Moviprep), either in two separate doses of 1 L or as a single 2-L dose. Participants donated faecal samples at the baseline, after bowel cleansing, 14 and 28 days after the treatment. The intestinal microbiota composition was determined with phylogenetic microarray as well as quantitative PCR analysis and correlated with the previously quantified faecal serine proteases. Results The lavage introduced an instant and substantial change to the intestinal microbiota. The total microbial load was decreased by 31-fold and 22% of the participants lost the subject-specificity of their microbiota. While the bacterial levels and community composition were essentially restored within 14 days, the rate of recovery was dose dependent: consumption of the purgative in a single dose had a more severe effect on the microbiota composition than that of a double dose, and notably increased the levels of Proteobacteria, Fusobacteria and bacteria related to Dorea formicigenerans. The abundance of the latter also correlated with the amount of faecal serine proteases that were increased after purging. Conclusions Our results suggest that the bowel cleansing using two separate dosages introduces fewer alterations to the intestinal microbiota than a single dose and hence may be preferred in clinical practice.

Long-term effects on luminal and mucosal microbiota and commonly acquired taxa in faecal microbiota transplantation for recurrent Clostridium difficile infection

BackgroundFaecal microbiota transplantation (FMT) is an effective treatment for recurrent Clostridium difficile infection (rCDI). It restores the disrupted intestinal microbiota and subsequently suppresses C. difficile. The long-term stability of the intestinal microbiota and the recovery of mucosal microbiota, both of which have not been previously studied, are assessed herein. Further, the specific bacteria behind the treatment efficacy are also investigated.MethodsWe performed a high-throughput microbiota profiling using a phylogenetic microarray analysis of 131 faecal and mucosal samples from 14 rCDI patients pre- and post-FMT during a 1-year follow-up and 23 samples from the three universal donors over the same period.ResultsThe FMT treatment was successful in all patients. FMT reverted the patients’ bacterial community to become dominated by Clostridium clusters IV and XIVa, the major anaerobic bacterial groups of the healthy gut. In the mucosa, the amount of facultative anaerobes decreased, whereas Bacteroidetes increased. Post-FMT, the patients’ microbiota profiles were more similar to their own donors than what is generally observed for unrelated subjects and this striking similarity was retained throughout the 1-year follow-up. Furthermore, the universal donor approach allowed us to identify bacteria commonly established in all CDI patients and revealed a commonly acquired core microbiota consisting of 24 bacterial taxa.ConclusionsFMT induces profound microbiota changes, therefore explaining the high clinical efficacy for rCDI. The identification of commonly acquired bacteria could lead to effective bacteriotherapeutic formulations. FMT can affect microbiota in the long-term and offers a means to modify it relatively permanently for the treatment of microbiota-associated diseases.

Microbial signatures in post-infectious irritable bowel syndrome – toward patient stratification for improved diagnostics and treatment

Irritable bowel syndrome (IBS) is a multifactorial and heterogeneous disorder estimated to affect over 10% of the Western population. A subset of the patients reports the start of the disease after an episode of gastroenteritis. The alterations in the intestinal microbiota of the post-infectious IBS (PI-IBS) patients were recently investigated in a British cohort and shown to differentiate from the healthy controls and resemble that of diarrhea-predominant IBS (IBS-D) patients. The altered 27 genus-like groups created a microbial signature, which could be used to objectively stratify patients and healthy controls. In this addendum, we combine the microbiota data derived from the British cohort with that of a recently reported Swedish PI-IBS cohort. Remarkably, robust and reproducible microbiota signatures were observed in these PI-IBS patients. We discuss these results with attention on the emerging role of microbiota in the classification, development and treatment of PI-IBS.

Fecal Transplantation Treatment of Antibiotic-Induced, Noninfectious Colitis and Long-Term Microbiota Follow-Up

Fecal microbiota transplantation (FMT) is an effective treatment for recurrent Clostridium difficile infection (CDI) and is considered as a treatment for other gastrointestinal (GI) diseases. We followed up the relief of symptoms and long-term, over-a-year microbiota stabilization in a 46-year-old man, who underwent FMT for antibiotic-induced, non-CDI colitis nine months after being treated for CDI by FMT. Fecal and mucosal microbiota was analyzed before the second FMT and during 14 months after FMT by using a high-throughput phylogenetic microarray. FMT resolved the symptoms and restored normal GI-function. Microbiota analysis revealed increased bacterial diversity in the rectal mucosa and a stable fecal microbiota up to three months after FMT. A number of mucosa-associated bacteria increased after FMT and some of these bacteria remained increased in feces up to 14 months. Notably, the increased bacteria included Bifidobacterium spp. and various representatives of Clostridium clusters IV and XIVa, such as Clostridium leptum, Oscillospira guillermondii, Sporobacter termitidis, Anaerotruncus colihominis, Ruminococcus callidus, R. bromii, Lachnospira pectinoschiza, and C. colinum, which are presumed to be anti-inflammatory. The presented case suggests a possible role of microbiota in restoring and maintaining normal GI-functionality and improves our knowledge on the etiology of antibiotic-induced, noninfectious colitis.

The long-term effects of faecal microbiota transplantation for gastrointestinal symptoms and general health in patients with recurrent Clostridium difficile infection

Faecal microbiota transplantation (FMT) is an effective treatment for recurrent Clostridium difficile infection. In short‐term the treatment has been shown to be safe, however, there are no large, long‐term follow‐up studies looking into the potential adverse effects.

The Potential of Gut Commensals in Reinforcing Intestinal Barrier Function and Alleviating Inflammation

The intestinal microbiota, composed of pro- and anti-inflammatory microbes, has an essential role in maintaining gut homeostasis and functionality. An overly hygienic lifestyle, consumption of processed and fiber-poor foods, or antibiotics are major factors modulating the microbiota and possibly leading to longstanding dysbiosis. Dysbiotic microbiota is characterized to have altered composition, reduced diversity and stability, as well as increased levels of lipopolysaccharide-containing, proinflammatory bacteria. Specific commensal species as novel probiotics, so-called next-generation probiotics, could restore the intestinal health by means of attenuating inflammation and strengthening the epithelial barrier. In this review we summarize the latest findings considering the beneficial effects of the promising commensals across all major intestinal phyla. These include the already well-known bifidobacteria, which use extracellular structures or secreted substances to promote intestinal health. Faecalibacterium prausnitzii, Roseburia intestinalis, and Eubacterium hallii metabolize dietary fibers as major short-chain fatty acid producers providing energy sources for enterocytes and achieving anti-inflammatory effects in the gut. Akkermansia muciniphila exerts beneficial action in metabolic diseases and fortifies the barrier function. The health-promoting effects of Bacteroides species are relatively recently discovered with the findings of excreted immunomodulatory molecules. These promising, unconventional probiotics could be a part of biotherapeutic strategies in the future.

Role of microbiota in the pathogenesis of functional disorders of the lower GI tract: Work in progress

Functional bowel disorders affect a significant proportion of people word wide. Patients suffer from longstanding symptoms of abdominal pain or discomfort in combination with abnormal bowel habits. The evidence for role of microbiota is currently contradictory and descriptive. This review aims to summarize the reasons which include methodological differences in DNA extraction and sample handling along with other factors such as diet, prior antibiotic use and transit, all important major determinants of microbiota which are difficult to control. Randomized studies of specific intervention in which such factors are varied may improve reproducibility and consistency of findings in future research.

The composition of the perinatal intestinal microbiota in cattle

Recent research suggests that the microbial colonization of the mammalian intestine may begin before birth, but the observations are controversial due to challenges in the reliable sampling and analysis of low-abundance microbiota. We studied the perinatal microbiota of calves by sampling them immediately at birth and during the first postnatal week. The large size of the bovine newborns allows sampling directly from rectum using contamination-shielded swabs. Our 16S rDNA data, purged of potential contaminant sequences shared with negative controls, indicates the existence of a diverse low-abundance microbiota in the newborn rectal meconium and mucosa. The newborn rectal microbiota was composed of Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. The microbial profile resembled dam oral rather than fecal or vaginal vestibular microbiota, but included typical intestinal taxa. During the first postnatal day, the rectum was invaded by Escherichia/Shigella and Clostridia, and the diversity collapsed. By 7 days, diversity was again increasing. In terms of relative abundance, Proteobacteria were replaced by Firmicutes, Bacteroidetes and Actinobacteria, including Faecalibacterium, Bacteroides, Lactobacillus, Butyricicoccus and Bifidobacterium. Our observations suggest that mammals are seeded before birth with a diverse microbiota, but the microbiota changes rapidly in the early postnatal life.

Publisher Correction: The composition of the perinatal intestinal microbiota in cattle

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