Alterations in the mucosa-associated bacterial composition in Crohn's disease: a pilot study

Liver cirrhosis and antibiotic therapy but not TIPS application leads to a shift of the intestinal bacterial communities: A controlled, prospective study

OBJECTIVES

The gut-liver axis is discussed to play an important role in hepatic cirrhosis. Decompensated liver cirrhosis is associated with portal hypertension, which can lead to a variety of complications. Transjugular intrahepatic portosystemic shunt (TIPS) is an established treatment option for the complications of portal hypertension. In this study we focused on the effect of TIPS on intestinal microbial composition in cirrhotic patients.

METHODS

Thirty patients with liver cirrhosis were compared to 18 healthy adults. Seventeen patients with cirrhosis and portal hypertension received a TIPS. Clinical characteristics, including age, sex, and liver function measured with a Child-Pugh score and model for end-stage liver disease score, were obtained. Intestinal microbial composition was assessed via 16S rRNA gene amplicon sequencing from stool probes before and after TIPS.

RESULTS

TIPS led to a reduction of hepatic venous pressure gradient. However, TIPS did not cause a shift in the intestinal bacterial communities. Independent from the application of TIPS, antibiotic therapy was associated with a significant difference in the intestinal bacterial microbiota and also a reduced α-diversity. In addition, a significant difference was observed in the intestinal bacterial composition between patients with liver cirrhosis and healthy controls.

CONCLUSION

The presence of liver cirrhosis and the use of antibiotic therapy, but not the application of TIPS, were associated with a significant shift of the intestinal bacterial communities, showing a high impact on the microbiota of patients with liver cirrhosis.

Ultrasound in Pediatric Inflammatory Bowel Disease-A Review of the State of the Art and Future Perspectives

Inflammatory bowel disease (IBD) comprises a group of relapsing, chronic diseases of the gastrointestinal tract that, in addition to adults, can affect children and adolescents. To detect relapses of inflammation, these patients require close observation, frequent follow-up, and therapeutic adjustments. While reference standard diagnostics include anamnestic factors, laboratory and stool sample assessment, performing specific imaging in children and adolescents is much more challenging than in adults. Endoscopic and classic cross-sectional imaging modalities may be invasive and often require sedation for younger patients. For this reason, intestinal ultrasound (IUS) is becoming increasingly important for the non-invasive assessment of the intestine and its inflammatory affection. In this review, we would like to shed light on the current state of the art and provide an outlook on developments in this field that could potentially spare these patients more invasive follow-up procedures.

Both Saccharomyces boulardii and Its Postbiotics Alleviate Dextran Sulfate Sodium-Induced Colitis in Mice, Association with Modulating Inflammation and Intestinal Microbiota

OBJECTIVE

To investigate the effect of Saccharomyces boulardii and its freeze-dried and spray-dried postbiotics on the intervention and potential mechanism of dextran sulfate sodium (DSS)-induced ulcerative colitis in mice. [Methods] After the acclimation period of C67BL/6J mice, a colitis model was constructed by applying 2% DSS for 7 d, followed by 7 d of intervention. Subsequently, the disease activity index (DAI), organ index, colon length, colon HE staining of pathological sections, ELISA for blood inflammatory factors (Interleukin (IL)-1β, IL-6, IL-10, Tumor necrosis factor (TNF)-α), Real time quantitative polymerase chain reaction (RT-qPCR) to determine the levels of colonic inflammatory factors (IL-1β, IL-6, IL-10, TNF-α), Occludin gene expression, and intestinal flora were assessed to evaluate the protective effects of S. boulardii and its postbiotics on colitis in mice.

RESULTS

Compared with the DSS group, S. boulardii and the postbiotics interventions effectively improved colonic shortening and tissue damage, increased the expression of intestinal tight junction protein, reduced the secretion of pro-inflammatory factors, increased the secretion of anti-inflammatory factors, and maintained the homeostasis of intestinal microorganisms. Postbiotics intervention is better than probiotics.

CONCLUSIONS

S. boulardii and its postbiotics can effectively alleviate DSS-induced colitis in mice through modulating host immunity and maintaining intestinal homeostasis. Postbiotics are promising next-generation biotherapeutics for ulcerative colitis treatment.

Eurotium cristatum, a Probiotic Fungus from Fuzhuan Brick Tea, and Its Polysaccharides Ameliorated DSS-Induced Ulcerative Colitis in Mice by Modulating the Gut Microbiota

Eurotium cristatum is a potential probiotic fungus that is used to enhance Fuzhuan tea quality through fermentation and could reduce obesity by modulating gut dysbiosis. This study aimed to investigate the effects and possible mechanisms of killed E. cristatum (KEC) and its polysaccharides (ECP) in ulcerative colitis (UC) relief. KEC and ECP were administered to mice with dextran sulfate sodium-induced UC. The results showed that UC severity, intestinal inflammation, and tight junction protein levels were greatly improved. Furthermore, 16S rRNA sequencing results showed that Escherichia coli, Enterococcus faecium, Clostridium perfringens, Bacteroides caccae, Rothia aeria, and Prevotella melaninogenica were depleted, while Alistipes finegoldii and Bacteroides stercorirosoris were enriched. A fecal microbial transplantation trial confirmed that KEC and ECP ameliorated UC by regulating gut dysbiosis. Thus, this research suggests that KEC and ECP are novel, potent, food-based anti-inflammatory agents that relieve UC by modulating gut dysbiosis.

Higher Prevalence of Bacteroides fragilis in Crohn's Disease Exacerbations and Strain-Dependent Increase of Epithelial Resistance

Bacteroides fragilis has previously been linked to Crohn's disease (CD) exacerbations, but results are inconsistent and underlying mechanisms unknown. This study investigates the epidemiology of B. fragilis and its virulence factors bft (enterotoxin) and ubiquitin among 181 CD patients and the impact on the intestinal epithelial barrier in vitro. The prevalence of B. fragilis was significantly higher in active (n = 69/88, 78.4%) as compared to remissive (n = 58/93, 62.4%, p = 0.018) CD patients. Moreover, B. fragilis was associated with intestinal strictures. Interestingly, the intestinal barrier function, as examined by transepithelial electrical resistance (TEER) measurements of Caco-2 monolayers, increased when exposed to secretomes of bft-positive (bft-1 and bft-2 isotype; increased TEER ∼160%, p < 0.001) but not when exposed to bft-negative strains. Whole metagenome sequencing and metabolomics, respectively, identified nine coding sequences and two metabolites that discriminated TEER-increasing from non-TEER-increasing strains. This study revealed a higher B. fragilis prevalence during exacerbation. Surprisingly, bft-positive secretomes increased epithelial resistance, but we excluded Bft as the likely causative factor.

Faecalibacterium prausnitzii: A Next-Generation Probiotic in Gut Disease Improvement

The researchers are paying more attention to the role of gut commensal bacteria in health development beyond the classical pathogens. It has been widely demonstrated that dysbiosis, which means the alternations of the gut microbial structure, is closely associated with development of intestinal chronic inflammation-related diseases such as inflammatory bowel disease (IBD), and even infectious diseases including bacterial and viral infection. Thus, for reshaping ecological balance, a growing body of the literatures have proposed numerous strategies to modulate the structure of the gut microbiota, which provide more revelation for amelioration of these inflammation or infection-related diseases. While the ameliorative effects of traditional probiotics seem negligeable, emerging next generation probiotics (NGPs) start to receive great attention as new preventive and therapeutic tools. Encouragingly, within the last decade, the intestinal symbiotic bacterium Faecalibacterium prausnitzii has emerged as the “sentinel of the gut,” with multifunction of anti-inflammation, gut barrier enhancement, and butyrate production. A lower abundance of F. prausnitzii has been shown in IBD, Clostridium difficile infection (CDI), and virus infection such as COVID-19. It is reported that intervention with higher richness of F. prausnitzii through dietary modulation, fecal microbiota transplantation, or culture strategy can protect the mice or the subjects from inflammatory diseases. Therefore, F. prausnitzii may have potential ability to reduce microbial translocation and inflammation, preventing occurrences of gastrointestinal comorbidities especially in COVID-19 patients.

Changes in the Intestinal Microbiota of Patients with Inflammatory Bowel Disease with Clinical Remission during an 8-Week Infliximab Infusion Cycle

This study investigated changes in the intestinal microbiota during 8-week infliximab maintenance therapy in inflammatory bowel disease (IBD) patients in clinical remission. Microbial compositional differences were analyzed according to the trough level of infliximab (TLI) and mucosal healing (MH) status. 16S rRNA gene-based microbiome profiling was performed on 10 and 74 fecal samples from 10 healthy volunteers and 40 adult IBD patients, respectively. Fecal sampling occurred at 1–2 weeks (1W) and 7–8 weeks (7W) after infliximab infusion. TLI was measured by ELISA at 8 weeks, immediately before the subsequent infusion; MH was evaluated by endoscopy within 3 months. There were no significant changes in microbial composition, species richness, or diversity indices between 1W and 7W. However, 7W samples from the patients with TLI ≥ 5 μg/mL showed an increased species richness compared with patients with TLI < 5 μg/mL, and patients with MH showed increased diversity compared with non-MH patients. Beta-diversity analysis showed clustering between samples in the MH and non-MH groups. LEfSe analysis identified differential composition of Faecalibacterium prausnitzii group according to TLI and MH. In conclusion, these results suggest the potential of fecal microbiota as a response indicator.

Probiotics and dietary intervention modulate the colonic mucosa-associated microbiota in high-fat diet populations

BACKGROUND/AIMS

Alterations in the gut microbiota due to a high-fat diet and diet-induced illness have been found in both mouse models and humans. Observational studies suggest that probiotic administration and diet shifts may treat diet-related diseases. However, the effect of these interventions on the colonic mucosa has not yet been elucidated. This study investigated the efficacy of probiotic supplementation and dietary intervention as prophylactic tools under high-fat diet conditions.

MATERIALS AND METHODS

A total of 36 volunteers that normally consumed a high-fat diet were enrolled and treated with either a control diet, a low-fat dietary intervention, Bifidobacterium triple viable capsule therapy, or a combination of a low-fat diet and Bifidobacterium triple viable capsule therapy. Pyrosequencing of the V3 and V4 regions of the 16S rRNA genes was conducted to determine the extent to which probiotics and dietary intervention altered the mucosal microbiota.

RESULTS

This study demonstrated that interventional treatment with probiotics and a low-fat diet increased the diversity of the mucosal microbes, dietary intervention alone produced the most significant effect, whereas the combined intervention exhibited no synergetic improvement. Pyrosequencing demonstrated that probiotics and dietary intervention significantly elevated the abundance of some bacterial taxa assigned to the phylum Firmicutes and the beneficial genera Prevotella, Gemmiger, Coprococcus, and Faecalibacterium and reduced some harmful bacterial taxa assigned to the phylum Proteobacteria and genus Streptophyta.

CONCLUSION

The results of this study suggested that the addition of probiotics and dietary intervention could improve the composition of the colonic mucosal microbiota in high-fat diet populations.

The Prophylactic Use of Bovine Colostrum in a Murine Model of TNBS-Induced Colitis

Simple Summary

Colostrum is the first milk secreted by the mammary glands, and it is very rich in bioactive components. Recently, the importance of bovine colostrum (BC) as a nutraceutical product has been emerging with regards to gastrointestinal diseases. One of the most widespread gastrointestinal disorders is the inflammatory bowel disease (IBD), a multifactorial chronic condition that has a powerful impact on the social life of millions of people. Because current therapy protocols neither ensure complete recovery from IBD nor are free of secondary side effects, the present study assessed the impact of a short-term prophylactic oral administration of BC in a murine model of TNBS-induced colitis. BC administration was both well tolerated and did not induce any pathological symptoms. It considerably modulated the response to inflammation through modifications of the TLR4 and cytokines gene expression profiles as well as that of the intestinal microbiota. Although further studies are needed to develop a precise therapeutic protocol of BC administration, it seems to have the potential to be used as a natural supplement in the treatment of IBD.

Abstract

This study investigated the effects of a short-term administration of bovine colostrum (BC) in a TNBS model of induced colitis. Colitis was induced by TNBS treatment after seven days of BC (BC group, n = 12) or saline (control group, n = 12) administration in mice. Clinical signs, histopathological characteristics, expression levels of Toll-like receptor 4 (TLR4), pro- and anti-inflammatory cytokines, and microbial composition were assessed. BC was well tolerated and did not induce any histological damage or clinical symptoms. After TNBS treatment, the BC group showed a reduction in body weight (BW) loss compared to Control (p < 0.05). Moreover, expression levels of TLR4 (p < 0.01), Interleukin-1β (IL-1β; p < 0.001), Interleukin-8 (IL-8; p < 0.001), and Interleukin-10 (IL-10; p < 0.001) were lower in mice administered with BC. Finally, Escherichia coli were higher (p < 0.05), while Enterococci (p < 0.001), Lactobacillus spp. (p < 0.001), and Bifidobacterium spp. (p < 0.05) were lower in Control than BC group. This study confirms that pre-treatment with BC modulates the expression of genes and the count of microbes involved in the etiopathogenesis of colitis.

Potential prebiotic effect of a long-chain dextran produced by Weissella cibaria: an in vitro evaluation

Dextrans are homopolysaccharides of D-glucose units produced by lactic acid bacteria. They have several technological applications and potential utilisation in positively modulating gut microbiota is attracting increasing attention. Whereas the prebiotic activity of low polymerisation degree (DP) dextrans has been established, high DP dextrans still deserve deeper investigation. In the present study, a long linear chain dextran produced by Weissella cibaria was compared to inulin with regards to the growth of specific health-related taxa and to the production of organic acids in pH-controlled batch cultures of intestinal microbiota. qPCR quantification of Lactobacillus, Bifidobacterium, Prevotella, Bacteroides fragilis, and Faecalibacterium prausnitzii revealed differences in their relative abundance, depending on the carbon source, that reflected the pattern of fermentation products determined by HPLC. Dextran mainly enhanced the relative amount of Prevotella and Bacteroides, consistently with a favourable acetate-propionate ratio suggesting a promising utilisation as functional ingredient in the food industry.

Exploring Bacteroidetes: Metabolic key points and immunological tricks of our gut commensals

Bacteroidetes are the largest phylum of Gram-negative bacteria inhabiting our gastrointestinal tract and are considered the leading players of the healthy state and sophisticated homeostasis safeguarded by gut microbiota. Furthermore, specific roles have been attributed to some Bacteroidetes genera in the development of immune dysregulation, systemic disease such as metabolic syndrome and also neurological disorders. Glycoproteins secretion, short fatty acids imbalance, toxins production and molecular mimicry are only a part of the functions exerted by these commensals interacting with the host. The aim of this review is to summarize the current knowledge on the recognized role of Bacteroidetes in physiological functions and pathological networks in order to define the needs for future research and clarify the potential role for targeted microbial therapies.

Action and function of Faecalibacterium prausnitzii in health and disease

Faecalibacterium prausnitzii, anaerobic bacteria, is one of the main components of gut microbiota and the most important butyrate-producing bacteria in the human colon. So far, this commensal bacterium has been considered as a bioindicator of human health, once when its population is altered (decreased), inflammatory processes are favored. Several reports in the literature highlighted that the amount of Faecalibacterium prausnitzii negatively correlates to the activity of inflammatory bowel disease and colorectal cancer. Therefore, counterbalancing dysbiosis using Faecalibacterium prausnitzii as a potential active component of probiotic formulations appears to be a promising therapeutic strategy for inflammatory bowel diseases and colorectal cancer. However, once this microbial is very sensitive to oxygen, the formulation development is a great challenge. In this review, we will focus our attention on Faecalibacterium prausnitzii biology, anti-inflammatory metabolites, modulators of this bacterium population and its impact on human health.

Elucidating the gut microbiome of ulcerative colitis: bifidobacteria as novel microbial biomarkers

Ulcerative colitis (UC) is associated with a substantial alteration of specific gut commensals, some of which may be involved in microbiota-mediated protection. In this study, microbiota cataloging of UC patients by 16S rRNA microbial profiling revealed a marked reduction of bifidobacteria, in particular the Bifidobacterium bifidum species, thus suggesting that this taxon plays a biological role in the aetiology of UC. We investigated this further through an in vivo trial by testing the effects of oral treatment with B. bifidum PRL2010 in a wild-type murine colitis model. TNBS-treated mice receiving 10(9) cells of B. bifidum PRL2010 showed a marked reduction of all colitis-associated histological indices as well as maintenance of mucosal integrity as it was shown by the increase in the expression of many tight junction-encoding genes. The protective role of B. bifidum PRL2010, as well as its sortase-dependent pili, appears to be established through the induction of an innate immune response of the host. These results highlight the importance of B. bifidum as a microbial biomarker for UC, revealing its role in protection against experimentally induced colitis.