Prebiotic Supplementation Following Ileocecal Resection in a Murine Model is Associated With a Loss of Microbial Diversity and Increased Inflammation

Changes in HLA-B27 Transgenic Rat Fecal Microbiota Following Tofacitinib Treatment and Ileocecal Resection Surgery: Implications for Crohn's Disease Management

The therapeutic management of Crohn's disease (CD), a chronic relapsing-remitting inflammatory bowel disease (IBD), is highly challenging. Surgical resection is sometimes a necessary procedure even though it is often associated with postoperative recurrences (PORs). Tofacitinib, an orally active small molecule Janus kinase inhibitor, is an anti-inflammatory drug meant to limit PORs in CD. Whereas bidirectional interactions between the gut microbiota and the relevant IBD drug are crucial, little is known about the impact of tofacitinib on the gut microbiota. The HLA-B27 transgenic rat is a good preclinical model used in IBD research, including for PORs after ileocecal resection (ICR). In the present study, we used shotgun metagenomics to first delineate the baseline composition and determinants of the fecal microbiome of HLA-B27 rats and then to evaluate the distinct impact of either tofacitinib treatment, ileocecal resection or the cumulative effect of both interventions on the gut microbiota in these HLA-B27 rats. The results confirmed that the microbiome of the HLA-B27 rats was fairly different from their wild-type littermates. We demonstrated here that oral treatment with tofacitinib does not affect the gut microbial composition of HLA-B27 rats. Of note, we showed that ICR induced an intense loss of bacterial diversity together with dramatic changes in taxa relative abundances. However, the oral treatment with tofacitinib neither modified the alpha-diversity nor exacerbated significant modifications in bacterial taxa induced by ICR. Collectively, these preclinical data are rather favorable for the use of tofacitinib in combination with ICR to address Crohn's disease management when considering microbiota.

Influence of the bile acid/microbiota axis in ileal surgery: a systematic review

AIM

The gastrointestinal bile acid (BA)/microbiota axis has emerged as a potential mediator of health and disease, particularly in relation to pathologies such as inflammatory bowel disease (IBD) and colorectal cancer. Whilst it presents an exciting new avenue for therapies, it has not yet been characterized in surgical resection of the ileum, where BA reabsorption occurs. The identification of BA/microbiota signatures may provide future therapies with perioperative personalized medicine. In this work we conduct a systematic review with the aim of investigating the microbiome and BA changes that are associated with resection of the ileum.

METHOD

The databases included were MEDLINE, EMBASE, Web of Science and Cochrane libraries. The outcomes of interest were faecal microbiome and BA signatures after ileal resection.

RESULTS

Of the initial 3106 articles, three studies met the inclusion/exclusion criteria for data extraction. A total of 257 patients (46% surgery, 54% nonsurgery controls) were included in the three studies. Two studies included patients with short bowel syndrome and the other included patients with IBD. Large-scale microbiota changes were reported. In general, alpha diversity had decreased amongst patients with ileal surgery. Phylum-level changes included decreased Bacteroidetes and increased Proteobacteria and Fusobacteria in patients with an intestinal resection. Surgery was associated with increased total faecal BAs, cholic acid and chenodeoxycholic acid. There were decreases in deoxycholic acid and glycine and taurine conjugated bile salts. Integrated BA and microbiota data identified correlations with several bacterial families and BA.

CONCLUSION

The BA/microbiota axis is still a novel area with minimal observational data in surgery. Further mechanistic research is necessary to further explore this and identify its role in improving perioperative outcomes.

Recipient microbiome-related features predicting metabolic improvement following fecal microbiota transplantation in adults with severe obesity and metabolic syndrome: a secondary analysis of a phase 2 clinical trial

Microbial-based therapeutics in clinical practice are of considerable interest, and a recent study demonstrated fecal microbial transplantation (FMT) followed by dietary fiber supplements improved glucose homeostasis. Previous evidence suggests that donor and recipient compatibility and FMT protocol are key determinants, but little is known about the involvement of specific recipient factors. Using data from our recent randomized placebo-control phase 2 clinical trial in adults with obesity and metabolic syndrome, we grouped participants that received FMT from one of 4 donors with either fiber supplement into HOMA-IR responders (n = 21) and HOMA-IR non-responders (n = 8). We further assessed plasma bile acids using targeted metabolomics and performed subgroup analyzes to evaluate the effects of recipient parameters and gastrointestinal factors on microbiota engraftment and homeostatic model assessment of insulin resistance (HOMA2-IR) response. The baseline fecal microbiota composition at genus level of recipients could predict the improvements in HOMA2-IR at week 6 (ROC-AUC = 0.70). Prevotella was identified as an important predictor, with responders having significantly lower relative abundance than non-responders (p = .02). In addition, recipients displayed a highly individualized degree of microbial engraftment from donors. Compared to the non-responders, the responders had significantly increased bacterial richness (Chao1) after FMT and a more consistent engraftment of donor-specific bacteria ASVs (amplicon sequence variants) such as Faecalibacillus intestinalis (ASV44), Roseburia spp. (ASV103), and Christensenellaceae spp. (ASV140) (p < .05). Microbiota engraftment was strongly associated with recipients' factors at baseline including initial gut microbial diversity, fiber and nutrient intakes, inflammatory markers, and bile acid derivative levels. This study identified that responders to FMT therapy had a higher engraftment rate in the transplantation of specific donor-specific microbes, which were strongly correlated with insulin sensitivity improvements. Further, the recipient baseline gut microbiota and related factors were identified as the determinants for responsiveness to FMT and fiber supplementation. The findings provide a basis for the development of precision microbial therapeutics for the treatment of metabolic syndrome.

What Do We Know about the Microbiome in Cystic Fibrosis? Is There a Role for Probiotics and Prebiotics?

Cystic fibrosis (CF) is a life-shortening genetic disorder that affects the cystic fibrosis transmembrane conductance regulator (CFTR) protein. In the gastrointestinal (GI) tract, CFTR dysfunction results in low intestinal pH, thick and inspissated mucus, a lack of endogenous pancreatic enzymes, and reduced motility. These mechanisms, combined with antibiotic therapies, drive GI inflammation and significant alteration of the GI microbiota (dysbiosis). Dysbiosis and inflammation are key factors in systemic inflammation and GI complications including malignancy. The following review examines the potential for probiotic and prebiotic therapies to provide clinical benefits through modulation of the microbiome. Evidence from randomised control trials suggest probiotics are likely to improve GI inflammation and reduce the incidence of CF pulmonary exacerbations. However, the highly variable, low-quality data is a barrier to the implementation of probiotics into routine CF care. Epidemiological studies and clinical trials support the potential of dietary fibre and prebiotic supplements to beneficially modulate the microbiome in gastrointestinal conditions. To date, limited evidence is available on their safety and efficacy in CF. Variable responses to probiotics and prebiotics highlight the need for personalised approaches that consider an individual’s underlying microbiota, diet, and existing medications against the backdrop of the complex nutritional needs in CF.

Fructooligosaccharide supplementation alleviated the pathological immune response and prevented the impairment of intestinal barrier in DSS-induced acute colitis mice

The dysbiosis of gut microbiota is closely related to the occurrence and development of inflammatory bowel disease (IBD). The manipulation of intestinal flora through prebiotics or probiotics is expected to induce and maintain the remission of IBD symptoms. 6-week-old C57BL/J mice were daily gavaged with fructooligosaccharides (FOS) or the synbiotic two weeks before the administration of dextran sulfate sodium (DSS). The supplementation of FOS or synbiotic could significantly ameliorate the body weight loss and colon histological damage in DSS-induced acute colitis mice. The altered composition of gut microbiota in acute colitis mice was reversed by FOS or Synbiotic supplementation, with a characteristic of decreased abundance of Mucispirillum. Both FOS and synbiotic mitigated DSS-induced loss of mucus protein (MUC2) and epithelium tight junction proteins (ZO-1, Occluding, Claudin1) in colon mucosa. The expression of pro-inflammatory cytokines (IL-6 and TNF-α) was decreased by FOS or synbiotic treatment, while the expression of Tbx21 and IL-10 was increased. The results suggested that the modulation of gut microbiota by FOS or synbiotic supplementation could decrease the inflammation potential of colonized commensals, which prevented the impairment of the intestinal barrier and induced a regulation of immune response in DSS-induced acute colitis mice.

Fecal microbial transplantation and fiber supplementation in patients with severe obesity and metabolic syndrome: a randomized double-blind, placebo-controlled phase 2 trial

Fecal microbial transplantation (FMT) from lean donors to patients with obesity has been associated with metabolic benefits, yet results so far have been inconsistent. In this study, we tested the application of daily fiber supplementation as an adjunct to FMT therapy to modulate cardiometabolic outcomes. We performed a double-blind randomized trial in patients with severe obesity and metabolic syndrome receiving oral FMT, to test high-fermentable (HF) and low-fermentable (LF) fiber supplements (NCT03477916). Seventy participants were randomized to the FMT-HF (n = 17), FMT-LF (n = 17), HF (n = 17) and LF (n = 19) groups. The primary outcome was the assessment of change in insulin sensitivity from baseline to 6 weeks using the homeostatic model assessment (HOMA2-IR/IS). After 6 weeks, only patients in the FMT-LF group had significant improvements in HOMA2-IR (3.16 ± 3.01 at 6 weeks versus 3.77 ± 3.57 at baseline; P = 0.02). No difference in HOMA2-IR was observed over this period for those in the FMT-HF group (3.25 ± 1.70 at 6 weeks versus 3.17 ± 1.72 at baseline; P = 0.8), the HF group (3.49 ± 1.43 at 6 weeks versus 3.26 ± 1.33 at baseline; P = 0.8) or the LF group (3.76 ± 2.01 at 6 weeks versus 3.56 ± 1.81 at baseline; P = 0.8). Interventions were safe and well-tolerated with no treatment-attributed serious adverse events. We provide proof of concept for the use of a single-dose oral FMT combined with daily low-fermentable fiber supplementation to improve insulin sensitivity in patients with severe obesity and metabolic syndrome.

Timing of Tributyrin Supplementation Differentially Modulates Gastrointestinal Inflammation and Gut Microbial Recolonization Following Murine Ileocecal Resection

BACKGROUND

Gastrointestinal surgery imparts dramatic and lasting imbalances, or dysbiosis, to the composition of finely tuned microbial ecosystems. The aim of the present study was to use a mouse ileocecal resection (ICR) model to determine if tributyrin (TBT) supplementation could prevent the onset of microbial dysbiosis or alternatively enhance the recovery of the gut microbiota and reduce gastrointestinal inflammation.

METHODS

Male wild-type (129 s1/SvlmJ) mice aged 8-15 weeks were separated into single cages and randomized 1:1:1:1 to each of the four experimental groups: control (CTR), preoperative TBT supplementation (PRE), postoperative TBT supplementation (POS), and combined pre- and postoperative supplementation (TOT). ICR was performed one week from baseline assessment with mice assessed at 1, 2, 3, and 4 weeks postoperatively. Primary outcomes included evaluating changes to gut microbial communities occurring from ICR to 4 weeks.

RESULTS

A total of 34 mice that underwent ICR (CTR n = 9; PRE n = 10; POS n = 9; TOT n = 6) and reached the primary endpoint were included in the analysis. Postoperative TBT supplementation was associated with an increased recolonization and abundance of anaerobic taxa including Bacteroides thetaiotomicorn, Bacteroides caecimuris, Parabacteroides distasonis, and Clostridia. The microbial recolonization of PRE mice was characterized by a bloom of aerotolerant organisms including Staphylococcus, Lactobacillus, Enteroccaceae, and Peptostreptococcacea. PRE mice had a trend towards decreased ileal inflammation as evidenced by decreased levels of IL-1β (p = 0.09), IL-6 (p = 0.03), and TNF-α (p < 0.05) compared with mice receiving TBT postoperatively. In contrast, POS mice had trends towards reduced colonic inflammation demonstrated by decreased levels of IL-6 (p = 0.07) and TNF-α (p = 0.07). These changes occurred in the absence of changes to fecal short-chain fatty acid concentrations or histologic injury scoring.

CONCLUSIONS

Taken together, the results of our work demonstrate that the timing of tributyrin supplementation differentially modulates gastrointestinal inflammation and gut microbial recolonization following murine ICR.

Effects of goat milk enriched with oligosaccharides on microbiota structures, and correlation between microbiota and short-chain fatty acids in the large intestine of the mouse

In this study, we explored the effects of combining goat milk and oligosaccharides on the large intestine environment of mice. A combination of goat milk with each of 3 oligosaccharides-stachyose, fructo-oligosaccharide (FOS), and a prebiotics mix-were independently fed to mice. We investigated composition changes in the microbiota of the large intestine using 16S rRNA gene sequencing; measured short-chain fatty acid content using gas chromatography-mass spectrometry; and performed a Spearman correlation analysis between microorganisms and short-chain fatty acids. Our results showed that microbial diversity in the large intestine decreased significantly in the FOS group. In terms of α diversity, microbial richness significantly declined in all 3 treatment groups; in terms of β diversity, the intestinal microbial structures clearly changed in the FOS group. The abundance of Bifidobacterium and Lactobacillus increased markedly in the FOS group compared with the other groups. Functional predictions showed that FOS reduced intestinal bacterial infections and improved the endocrine and immune systems. Spearman correlation analysis showed that propionic, isobutyric, and valeric acids were all positively correlated with certain microbiota. Our findings suggest that FOS-enriched goat milk is beneficial for improving the large intestine environment in the host.

Heat shock protein 70 protects the quail cecum against oxidant stress, inflammatory injury, and microbiota imbalance induced by cold stress

The intent of this study was to investigate the effects of cold stress on oxidative indexes, inflammatory factors, and microbiota in the quail cecum. A total of 192 male quails (15-day-old) were randomly divided into 12 groups (16 in each group) and were exposed to acute (up to 12 h) and chronic (up to 20 D) cold stress at 12 ± 1°C. After cold stress treatment, we examined morphological damage, oxidative stress indexes, inflammatory factors, and intestinal microbiota. Results of morphological examination showed that both acute and chronic cold stress can lead to cecal tissue injury. In addition, both acute and chronic cold stress, especially chronic cold stress can influence the activity of oxidative stress mediators. Glutathione (GSH) and glutathione peroxidase (GSH-Px) activities decreased significantly (p < 0.05), while the nitric oxide (NO) content and inducible nitric oxide synthase (iNOS) activity increased significantly (p < 0.05). Moreover, mRNA levels of inflammatory factors cyclooxygenase-2 (COX-2), prostaglandin E synthase (PTGES), and heat shock protein 70 (Hsp70) were higher in both acute and chronic cold stress groups when compared with the control group (p < 0.05). Furthermore, the intestinal microbiota was changed in both the acute and chronic cold stress groups. These results suggested that cold stress caused oxidative stress and inflammatory injury in cecal tissues, influenced cecal microbiota, and increased expression of Hsp70, which may contribute in protecting the cecum against cold stress in quails.

Amylose resistant starch (HAM-RS2) supplementation increases the proportion of Faecalibacterium bacteria in end-stage renal disease patients: Microbial analysis from a randomized placebo-controlled trial

INTRODUCTION

Many of the deleterious effects associated with chronic kidney disease (CKD) are secondary to the resultant systemic inflammation. The gut microbial changes caused by CKD are thought to perpetuate systemic inflammation. Therefore, strategies aimed at modulating the gut microbiota may be helpful in reducing complications associated with CKD. We hypothesized that supplementation with high-amylose maize resistant starch type 2 (HAM-RS2) would beneficially alter the gut microbiome and lead to lower levels of systemic inflammation.

METHODS

A double-blind, parallel, randomized, placebo-controlled trial was performed comparing dietary supplementation of HAM-RS2 with placebo in patients with end-stage CKD. Fecal microbial data were obtained from a subset of patients after DNA extraction and 16s sequencing.

FINDINGS

Supplementation of HAM-RS2 led to a decrease in serum urea, IL-6, TNFα, and malondialdehyde (P < 0.05). The Faecalibacterium genus was significantly increased in relative abundance following HAM-RS2 supplementation (HAM-RS2-Day 0: 0.40 ± 0.50 vs. HAM-RS2-Day 56: 3.21 ± 4.97 P = 0.03) and was unchanged by placebo (Control-Day 0: 0.72 ± 0.72 vs. Control-Day 56: 0.83 ± 1.57 P = 0.5).

DISCUSSION

Supplementation of amylose resistant starch, HAM-RS2, in patients with CKD led to an elevation in Faecalibacterium and decrease in systemic inflammation. Microbial manipulation in CKD patients by using the prebiotic fiber may exert an anti-inflammatory effect through an elevation in the bacterial genera Faecalibacterium.