Rapid dietary changes, such as switching from high-forage to high-grain diets, can modify the rumen microbiome and initiate gastrointestinal distress, such as bloating. In such cases, feed additives, including prebiotics and live microbials, can be used to mitigate these negative consequences. Bio-Mos® is a carbohydrate-based prebiotic derived from yeast cells that is reported to increase livestock performance. Here, the responses of rumen bacterial cells to Bio-Mos® were quantified, sorted by flow cytometry using fluorescently-labeled yeast mannan, and taxonomically characterized using fluorescence in situ hybridization and 16S rRNA sequencing. Further, to evaluate the effects of bovine-adapted Bacteroides thetaiotaomicron administration as a live microbial with and without Bio-Mos® supplementation, we analyzed microbial fermentation products, changes to carbohydrate profiles, and shifts in microbial composition of an in vitro rumen community. Bio-Mos® was shown to be an effective prebiotic that significantly altered microbial diversity, composition, and fermentation; while addition of B. thetaiotaomicron had no effect on community composition and resulted in fewer significant changes to microbial fermentation. When combined with Bio-Mos®, there were notable, although not significant, changes to major bacterial taxa, along with increased significant changes in fermentation end products. These data suggest a synergistic effect is elicited by combining Bio-Mos® and B. thetaiotaomicron . This protocol provides a new in vitro methodology that could be extended to evaluate prebiotics and probiotics in more complex artificial rumen systems and live animals.
<div>Abstract<p>Several approaches to manipulate the gut microbiome for improving the activity of cancer immune-checkpoint inhibitors (ICI) are currently under evaluation. Here, we show that oral supplementation with the polyphenol-rich berry camu-camu (CC; <i>Myrciaria dubia</i>) in mice shifted gut microbial composition, which translated into antitumor activity and a stronger anti–PD-1 response. We identified castalagin, an ellagitannin, as the active compound in CC. Oral administration of castalagin enriched for bacteria associated with efficient immunotherapeutic responses (<i>Ruminococcaceae</i> and <i>Alistipes</i>) and improved the CD8<sup>+</sup>/FOXP3<sup>+</sup>CD4<sup>+</sup> ratio within the tumor microenvironment. Moreover, castalagin induced metabolic changes, resulting in an increase in taurine-conjugated bile acids. Oral supplementation of castalagin following fecal microbiota transplantation from ICI-refractory patients into mice supported anti–PD-1 activity. Finally, we found that castalagin binds to <i>Ruminococcus bromii</i> and promoted an anticancer response. Altogether, our results identify castalagin as a polyphenol that acts as a prebiotic to circumvent anti–PD-1 resistance.</p>Significance:<p>The polyphenol castalagin isolated from a berry has an antitumor effect through direct interactions with commensal bacteria, thus reprogramming the tumor microenvironment. In addition, in preclinical ICI-resistant models, castalagin reestablishes the efficacy of anti–PD-1. Together, these results provide a strong biological rationale to test castalagin as part of a clinical trial.</p><p><i>This article is highlighted in the In This Issue feature, p. 873</i></p></div>
Splenic metastasis of colon cancer is uncommon especially when isolated. In fact, they are usually associated to multi visceral location. Malignant melanoma, cancer of breast and lung and ovarian carcinoma are the most common cancer which metastases in spleen. Splenic metastasis of colon cancer is rare and exceptionally isolated. Ten cases of isolated splenic metastasis in colon cancer are reported in literature. We report a new case of intra splenic kystic metastasis revealing an asymptomatic sigmoid cancer in a 63 years old patient.
ABSTRACT Dietary fibers influence the composition of the human gut microbiota and directly contribute to its downstream effects on host health. As more research supports the use of glycans as prebiotics for therapeutic applications, the need to identify the gut bacteria that metabolize glycans of interest increases. Fructo-oligosaccharide (FOS) is a common diet-derived glycan that is fermented by the gut microbiota and has been used as a prebiotic. Despite being well studied, we do not yet have a complete picture of all FOS-consuming gut bacterial taxa. To identify new bacterial consumers, we used a short exposure of microbial communities in a stool sample to FOS or galactomannan as the sole carbon source to induce glycan metabolism genes. We then performed metatranscriptomics, paired with whole metagenomic sequencing, and 16S amplicon sequencing. The short incubation was sufficient to cause induction of genes involved in carbohydrate metabolism, like carbohydrate-active enzymes (CAZymes), including glycoside hydrolase family 32 genes, which hydrolyze fructan polysaccharides like FOS and inulin. Interestingly, FOS metabolism transcripts were notably overexpressed in Blautia species not previously reported to be fructan consumers. We therefore validated the ability of different Blautia species to ferment fructans by monitoring their growth and fermentation in defined media. This pulse metatranscriptomics approach is a useful method to find novel consumers of prebiotics and increase our understanding of prebiotic metabolism by CAZymes in the gut microbiota. IMPORTANCE Complex carbohydrates are key contributors to the composition of the human gut microbiota and play an essential role in the microbiota’s effects on host health. Understanding which bacteria consume complex carbohydrates, or glycans, provides a mechanistic link between dietary prebiotics and their beneficial health effects, an essential step for their therapeutic application. Here, we used a pulse metatranscriptomics pipeline to identify bacterial consumers based on glycan metabolism induction in a human stool sample. We identified novel consumers of fructo-oligosaccharide among Blautia species, expanding our understanding of this well-known glycan. Our approach can be applied to identify consumers of understudied glycans and expand our prebiotic repertoire. It can also be used to study prebiotic glycans directly in stool samples in distinct patient populations to help delineate the prebiotic mechanism.
<div>Abstract<p>Several approaches to manipulate the gut microbiome for improving the activity of cancer immune-checkpoint inhibitors (ICI) are currently under evaluation. Here, we show that oral supplementation with the polyphenol-rich berry camu-camu (CC; <i>Myrciaria dubia</i>) in mice shifted gut microbial composition, which translated into antitumor activity and a stronger anti–PD-1 response. We identified castalagin, an ellagitannin, as the active compound in CC. Oral administration of castalagin enriched for bacteria associated with efficient immunotherapeutic responses (<i>Ruminococcaceae</i> and <i>Alistipes</i>) and improved the CD8<sup>+</sup>/FOXP3<sup>+</sup>CD4<sup>+</sup> ratio within the tumor microenvironment. Moreover, castalagin induced metabolic changes, resulting in an increase in taurine-conjugated bile acids. Oral supplementation of castalagin following fecal microbiota transplantation from ICI-refractory patients into mice supported anti–PD-1 activity. Finally, we found that castalagin binds to <i>Ruminococcus bromii</i> and promoted an anticancer response. Altogether, our results identify castalagin as a polyphenol that acts as a prebiotic to circumvent anti–PD-1 resistance.</p>Significance:<p>The polyphenol castalagin isolated from a berry has an antitumor effect through direct interactions with commensal bacteria, thus reprogramming the tumor microenvironment. In addition, in preclinical ICI-resistant models, castalagin reestablishes the efficacy of anti–PD-1. Together, these results provide a strong biological rationale to test castalagin as part of a clinical trial.</p><p><i>This article is highlighted in the In This Issue feature, p. 873</i></p></div>
Urolithin A (uroA) is a polyphenol derived from the multi-step metabolism of dietary ellagitannins by the human gut microbiota. Once absorbed, uroA can trigger mitophagy and aryl hydrocarbon receptor signaling pathways, altering host immune function, mitochondrial health, and intestinal barrier integrity. Most individuals harbor a microbiota capable of uroA production; however, the mechanisms underlying the dehydroxylation of its catechol-containing precursor (uroC) are unknown. Here, we use a combination of untargeted bacterial transcriptomics, proteomics, and comparative genomics to uncover an inducible uroC dehydroxylase (ucd) operon in Enterocloster species. We show that the ucd operon encodes a predicted molybdopterin-dependent enzyme complex that dehydroxylates urolithins at a specific position (9-OH). By interrogating publicly available metagenomics datasets, we observed that uroC-metabolizing Enterocloster species and ucd operon genes are prevalent in human feces. In ex vivo experiments with human fecal samples, only samples actively transcribing ucd could produce uroA, possibly explaining differences in urolithin metabolism between individuals. Collectively, this work identifies Enterocloster species and the ucd operon as important contributors to uroA production and establishes a multi-omics framework to further our mechanistic understanding of polyphenol metabolism by the human gut microbiota. Here, using a multi-omics framework, the authors show that Urolithin A, a mitophagy-promoting compound derived from the metabolism of dietary ellagitannins by the gut microbiota, is produced by prevalent urolithin C dehydroxylase-expressing Enterocloster species.
Abstract Several approaches to manipulate the gut microbiome for improving the activity of cancer immune-checkpoint inhibitors (ICI) are currently under evaluation. Here, we show that oral supplementation with the polyphenol-rich berry camu-camu (CC; Myrciaria dubia) in mice shifted gut microbial composition, which translated into antitumor activity and a stronger anti–PD-1 response. We identified castalagin, an ellagitannin, as the active compound in CC. Oral administration of castalagin enriched for bacteria associated with efficient immunotherapeutic responses (Ruminococcaceae and Alistipes) and improved the CD8+/FOXP3+CD4+ ratio within the tumor microenvironment. Moreover, castalagin induced metabolic changes, resulting in an increase in taurine-conjugated bile acids. Oral supplementation of castalagin following fecal microbiota transplantation from ICI-refractory patients into mice supported anti–PD-1 activity. Finally, we found that castalagin binds to Ruminococcus bromii and promoted an anticancer response. Altogether, our results identify castalagin as a polyphenol that acts as a prebiotic to circumvent anti–PD-1 resistance. Significance: The polyphenol castalagin isolated from a berry has an antitumor effect through direct interactions with commensal bacteria, thus reprogramming the tumor microenvironment. In addition, in preclinical ICI-resistant models, castalagin reestablishes the efficacy of anti–PD-1. Together, these results provide a strong biological rationale to test castalagin as part of a clinical trial. This article is highlighted in the In This Issue feature, p. 873
