Production of butyrate from lysine and the Amadori product fructoselysine by a human gut commensal

The Human Microbiome as a Therapeutic Target for Metabolic Diseases

The human microbiome functions as a separate organ in a symbiotic relationship with the host. Disruption of this host-microbe symbiosis can lead to serious health problems. Modifications to the composition and function of the microbiome have been linked to changes in host metabolic outcomes. Industrial lifestyles with high consumption of processed foods, alcoholic beverages and antibiotic use have significantly altered the gut microbiome in unfavorable ways. Therefore, understanding the causal relationship between the human microbiome and host metabolism will provide important insights into how we can better intervene in metabolic health. In this review, I will discuss the potential use of the human microbiome as a therapeutic target to improve host metabolism.

Glycation reactions of methylglyoxal during digestion in a dynamic, in vitro model of the upper gastrointestinal tract (TIM-1)

The 1,2-dicarbonyl compound methylglyoxal (MGO) can react with and thereby impair the function of proteins and DNA, leading to pathophysiological pathways in vivo. However, studies on the bioavailability of dietary MGO and its reactions during digestion have diverging results. Therefore, simulated digestion experiments of MGO, protein, and creatine were performed in the dynamic, in vitro model of the upper gastrointestinal tract (TIM-1). This multicompartment model continuously adjusts pH values and has realistic gastrointestinal transit times while also removing water and metabolites by dialysis. Samples were analyzed with HPLC-UV for MGO and HPLC-MS/MS for creatine and glycated amino compounds. MGO reacted with creatine during simulated digestion in TIM-1 to form the hydroimidazolone MG-HCr in similar amounts as in a human intervention study. 28%-69% of MGO from the meal were passively absorbed in TIM-1, depending on the addition of creatine and protein. Simultaneous digestion of MGO with ovalbumin led to the formation of the lysine adduct N ε -carboxyethyllysine (CEL) and the methylglyoxal-derived hydroimidazolone of arginine (MG-H1). The formation of both compounds decreased with added creatine. Hence, glycation compounds are formed during digestion and significantly contribute to other ingested dietary glycation compounds, whose physiological consequences are critically discussed.

Nutrient acquisition strategies by gut microbes

The composition and function of the gut microbiota are intimately tied to nutrient acquisition strategies and metabolism, with significant implications for host health. Both dietary and host-intrinsic factors influence community structure and the basic modes of bacterial energy metabolism. The intestinal tract is rich in carbon and nitrogen sources; however, limited access to oxygen restricts energy-generating reactions to fermentation. By contrast, increased availability of electron acceptors during episodes of intestinal inflammation results in phylum-level changes in gut microbiota composition, suggesting that bacterial energy metabolism is a key driver of gut microbiota function. In this review article, we will illustrate diverse examples of microbial nutrient acquisition strategies in the context of habitat filters and anatomical location and the central role of energy metabolism in shaping metabolic strategies to support bacterial growth in the mammalian gut.

Short-Chain Fatty Acids and Human Health: From Metabolic Pathways to Current Therapeutic Implications

The gastrointestinal tract is home to trillions of diverse microorganisms collectively known as the gut microbiota, which play a pivotal role in breaking down undigested foods, such as dietary fibers. Through the fermentation of these food components, short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate are produced, offering numerous health benefits to the host. The production and absorption of these SCFAs occur through various mechanisms within the human intestine, contingent upon the types of dietary fibers reaching the gut and the specific microorganisms engaged in fermentation. Medical literature extensively documents the supplementation of SCFAs, particularly butyrate, in the treatment of gastrointestinal, metabolic, cardiovascular, and gut-brain-related disorders. This review seeks to provide an overview of the dynamics involved in the production and absorption of acetate, propionate, and butyrate within the human gut. Additionally, it will focus on the pivotal roles these SCFAs play in promoting gastrointestinal and metabolic health, as well as their current therapeutic implications.

Dynamic effects of black soldier fly larvae meal on the cecal bacterial microbiota and prevalence of selected antimicrobial resistant determinants in broiler chickens

BACKGROUND

We had earlier described the growth-promoting and -depressive effects of replacing soybean meal (SBM) with low (12.5% and 25%) and high (50% and 100%) inclusion levels of black soldier fly larvae meal (BSFLM), respectively, in Ross x Ross 708 broiler chicken diets. Herein, using 16S rRNA gene amplicon sequencing, we investigated the effects of replacing SBM with increasing inclusion levels (0-100%) of BSFLM in broiler diets on the cecal bacterial community composition at each growth phase compared to broilers fed a basal corn-SBM diet with or without the in-feed antibiotic, bacitracin methylene disalicylate (BMD). We also evaluated the impact of low (12.5% and 25%) inclusion levels of BSFLM (LIL-BSFLM) on the prevalence of selected antimicrobial resistance genes (ARGs) in litter and cecal samples from 35-day-old birds.

RESULTS

Compared to a conventional SBM-based broiler chicken diet, high (50 to100%) inclusion levels of BSFLM (HIL-BSFLM) significantly altered the cecal bacterial composition and structure, whereas LIL-BSFLM had a minimal effect. Differential abundance analysis further revealed that the ceca of birds fed 100% BSFLM consistently harbored a ~ 3 log-fold higher abundance of Romboutsia and a ~ 2 log-fold lower abundance of Shuttleworthia relative to those fed a BMD-supplemented control diet at all growth phases. Transient changes in the abundance of several potentially significant bacterial genera, primarily belonging to the class Clostridia, were also observed for birds fed HIL-BSFLM. At the finisher phase, Enterococci bacteria were enriched in the ceca of chickens raised without antibiotic, regardless of the level of dietary BSFLM. Additionally, bacitracin (bcrR) and macrolide (ermB) resistance genes were found to be less abundant in the ceca of chickens fed antibiotic-free diets, including either a corn-SBM or LIL-BSFLM diet.

CONCLUSIONS

Chickens fed a HIL-BSFLM presented with an imbalanced gut bacterial microbiota profile, which may be linked to the previously reported growth-depressing effects of a BSFLM diet. In contrast, LIL-BSFLM had a minimal effect on the composition of the cecal bacterial microbiota and did not enrich for selected ARGs. Thus, substitution of SBM with low levels of BSFLM in broiler diets could be a promising alternative to the antibiotic growth promoter, BMD, with the added-value of not enriching for bacitracin- and macrolide-associated ARGs.

The Potential of Clostridium butyricum to Preserve Gut Health, and to Mitigate Non-AIDS Comorbidities in People Living with HIV

A dramatic reduction in mortality among people living with HIV (PLWH) has been achieved during the modern antiretroviral therapy (ART) era. However, ART does not restore gut barrier function even after long-term viral suppression, allowing microbial products to enter the systemic blood circulation and induce chronic immune activation. In PLWH, a chronic state of systemic inflammation exists and persists, which increases the risk of development of inflammation-associated non-AIDS comorbidities such as metabolic disorders, cardiovascular diseases, and cancer. Clostridium butyricum is a human butyrate-producing symbiont present in the gut microbiome. Convergent evidence has demonstrated favorable effects of C. butyricum for gastrointestinal health, including maintenance of the structural and functional integrity of the gut barrier, inhibition of pathogenic bacteria within the intestine, and reduction of microbial translocation. Moreover, C. butyricum supplementation has been observed to have a positive effect on various inflammation-related diseases such as diabetes, ulcerative colitis, and cancer, which are also recognized as non-AIDS comorbidities associated with epithelial gut damage. There is currently scant published research in the literature, focusing on the influence of C. butyricum in the gut of PLWH. In this hypothesis review, we speculate the use of C. butyricum as a probiotic oral supplementation may well emerge as a potential future synergistic adjunctive strategy in PLWH, in tandem with ART, to restore and consolidate intestinal barrier integrity, repair the leaky gut, prevent microbial translocation from the gut, and reduce both gut and systemic inflammation, with the ultimate objective of decreasing the risk for development of non-AIDS comorbidities in PLWH.

Metabolization of the Amadori Product N-ε-Fructosyllysine by Probiotic Bacteria

Glycation reactions in food lead to the formation of the Amadori rearrangement product (ARP) N-ε-fructosyllysine (fructoselysine, FL), which is taken up with the daily diet and comes into contact with the gut microbiota during digestion. In the present study, nine commercially available probiotic preparations as well as single pure strains thereof were investigated for their FL-degrading capability under anaerobic conditions. One of the commercial preparations as well as three single pure strains thereof was able to completely degrade 0.25 mM FL within 72 h. Three new deglycating lactic acid bacteria species, namely, Lactobacillus buchneri DSM 20057, Lactobacillus jensenii DSM 20557, and Pediococcus acidilactici DSM 25404, could be identified. Quantitative experiments showed that FL was completely deglycated to lysine. Using 13C6-labeled FL as the substrate, it could be proven that the sugar moiety of the Amadori product is degraded to lactic acid, showing for the first time that certain lactic acid bacteria can utilize the sugar moiety as a substrate for lactic acid fermentation.

Gut microbiota dysbiosis alters chronic pain behaviors in a humanized transgenic mouse model of sickle cell disease

ABSTRACT

Pain is the most common symptom experienced by patients with sickle cell disease (SCD) throughout their lives and is the main cause of hospitalization. Despite the progress that has been made towards understanding the disease pathophysiology, major gaps remain in the knowledge of SCD pain, the transition to chronic pain, and effective pain management. Recent evidence has demonstrated a vital role of gut microbiota in pathophysiological features of SCD. However, the role of gut microbiota in SCD pain is yet to be explored. We sought to evaluate the compositional differences in the gut microbiota of transgenic mice with SCD and nonsickle control mice and investigate the role of gut microbiota in SCD pain by using antibiotic-mediated gut microbiota depletion and fecal material transplantation (FMT). The antibiotic-mediated gut microbiota depletion did not affect evoked pain but significantly attenuated ongoing spontaneous pain in mice with SCD. Fecal material transplantation from mice with SCD to wild-type mice resulted in tactile allodynia (0.95 ± 0.17 g vs 0.08 ± 0.02 g, von Frey test, P < 0.001), heat hyperalgesia (15.10 ± 0.79 seconds vs 8.68 ± 1.17 seconds, radiant heat, P < 0.01), cold allodynia (2.75 ± 0.26 seconds vs 1.68 ± 0.08 seconds, dry ice test, P < 0.01), and anxiety-like behaviors (Elevated Plus Maze Test, Open Field Test). On the contrary, reshaping gut microbiota of mice with SCD with FMT from WT mice resulted in reduced tactile allodynia (0.05 ± 0.01 g vs 0.25 ± 0.03 g, P < 0.001), heat hyperalgesia (5.89 ± 0.67 seconds vs 12.25 ± 0.76 seconds, P < 0.001), and anxiety-like behaviors. These findings provide insights into the relationship between gut microbiota dysbiosis and pain in SCD, highlighting the importance of gut microbial communities that may serve as potential targets for novel pain interventions.

Association of Long-Term Habitual Dietary Fiber Intake since Infancy with Gut Microbiota Composition in Young Adulthood

BACKGROUND

Dietary fiber is an important health-promoting component of the diet, which is fermented by the gut microbes that produce metabolites beneficial for the host's health.

OBJECTIVES

We studied the associations of habitual long-term fiber intake from infancy with gut microbiota composition in young adulthood by leveraging data from the Special Turku Coronary Risk Factor Intervention Project, an infancy-onset 20-y dietary counseling study.

METHODS

Fiber intake was assessed annually using food diaries from infancy ≤ age 20 y. At age 26 y, the first postintervention follow-up study was conducted including food diaries and fecal sample collection (N = 357). Cumulative dietary fiber intake was assessed as the area under the curve for energy-adjusted fiber intake throughout the study (age 0-26 y). Gut microbiota was profiled using 16S ribosomal ribonucleic acid amplicon sequencing. The primary outcomes were 1) α diversity expressed as the observed richness and Shannon index, 2) β diversity using Bray-Curtis dissimilarity scores, and 3) differential abundance of each microbial taxa with respect to the cumulative energy-adjusted dietary fiber intake.

RESULTS

Higher cumulative dietary fiber intake was associated with decreased Shannon index (β = -0.019 per unit change in cumulative fiber intake, P = 0.008). Overall microbial community composition was related to the amount of fiber consumed (permutational analysis of variation R2 = 0.005, P = 0.024). The only genus that was increased with higher cumulative fiber intake was butyrate-producing Butyrivibrio (log2 fold-change per unit change in cumulative fiber intake 0.40, adjusted P = 0.023), whereas some other known butyrate producers such as Faecalibacterium and Subdoligranulum were decreased with higher cumulative fiber intake.

CONCLUSIONS

As early-life nutritional exposures may affect the lifetime microbiota composition and disease risk, this study adds novel information on the associations of long-term dietary fiber intake with the gut microbiota. This trial was registered at clinicaltrials.gov as NCT00223600.

Effect of an Alliaceae Encapsulated Extract on Growth Performance, Gut Health, and Intestinal Microbiota in Broiler Chickens Challenged with Eimeria spp

This study analyzed the effects of an Alliaceae encapsulated extract (AE-e) on daily gain (ADG), feed intake (ADFI), feed conversion ratio (FCR), oocysts per gram of feces (OPG), intestinal lesion (LS), and microbiota composition in broilers challenged with Eimeria spp. A total of 4800 one day Cobb-500 were allotted into 10 treatment groups with 12 replicates of 40 birds in a 2 × 4 + 2 factorial arrangement. The first factor was non-challenged (NC) or challenged (C), the second was four levels of AE-e added in the basal diet, 0 (AE0), 250 (AE250), 500 (AE500), and 750 mg·kg-1 (AE750), plus two ionophore controls, non-challenged (NC-Ion) and challenged (C-Ion). No interactions were observed between factors (NC0, NC250, NC500, NC750, C0, C250, C500, and C750), while C-Ion improved FCR at 21 d. The challenge affected negatively ADG and FCR and promoted enteropathogens in cecum. AE750 improved FCR in the finisher and cumulative phases, while C-Ion had fewer total OPG than C0 and C250. Likewise, at 21d, C250, C500, and C-Ion had fewer LS than C0, while at 28 d, C750 showed lower than C-Ion. In the cecum microbiota, C500 had more Ruminococcus, Firmicutes b, and Intestinimonas than C-Ion. In summary, AE-e showed beneficial results in broilers infected with Eimeria spp.

Non-canonical food sources: bacterial metabolism of Maillard reaction products and its regulation

Proteins are an important part of our regular diet. During food processing, their amino acid composition can be chemically altered by the reaction of free amino groups with sugars - a process termed glycation. The resulting Maillard reaction products (MRPs) have low bioavailability and thus predominantly end up in the colon where they encounter our gut microbiota. In the following review, we summarize bacterial strategies to efficiently metabolize these non-canonical amino acids. A particular focus will be on the complex regulatory mechanisms that allow a tightly controlled expression of metabolic genes to successfully occupy the ecological niches that result from the chemical diversity of MRPs.

A dietary intervention for postmenopausal hot flashes: A potential role of gut microbiome. An exploratory analysis

OBJECTIVE

This study examined the role of gut microbiome changes in mediating the effects of a dietary intervention on the frequency and severity of postmenopausal vasomotor symptoms METHODS: Postmenopausal women (n = 84) reporting ≥2 moderate-to-severe hot flashes daily were randomly assigned, in 2 successive cohorts, to an intervention including a low-fat, vegan diet and cooked soybeans (½ cup [86 g] daily) or to stay on their usual diet. Over a 12-week period, frequency and severity of hot flashes were recorded with a mobile application. In a subset of 11 women, gut microbiome was analyzed at baseline and after 12 weeks of the dietary intervention (low-fat vegan diet with soybeans), using deep shotgun metagenomic sequencing. Differences in the microbiome between baseline and 12 weeks were assessed by comparing alpha diversity with Wilcoxon signed rank tests, beta diversity with permanovaFL, and taxon abundance with Wilcoxon signed rank tests. Pearson correlations were used to assess the association between changes in hot flashes and gut bacteria.

RESULTS

In the subset for which microbiome testing was done, total hot flashes decreased by 95 % during the dietary intervention (p = 0.007); severe hot flashes disappeared (from 0.6 to 0.0/day; p = 0.06); and moderate-to-severe hot flashes decreased by 96 % (p = 0.01). Daytime and nighttime hot flashes were reduced by 96 % (p = 0.01) and 94 % (p = 0.004), respectively. Alpha and beta diversity did not significantly differ in the intervention group between baseline and 12 weeks. Two families (Enterobacteriaceae and Veillonellaceae), 5 genera (Erysipelatoclostridium, Fusicatenibacter, Holdemanella, Intestinimonas, and Porphyromonas), and 6 species (Clostridium asparagiforme, Clostridium innocuum, Bacteroides thetaiotaomicron, Fusicatenibacter saccharivorans, Intestinimonas butyriciproducens, Prevotella corporis, and Streptococcus sp.) were differentially abundant, but after correction for multiple comparisons, these differences were no longer significant. Changes in the relative abundance of Porphyromonas and Prevotella corporis were associated with the reduction in severe day hot flashes both unadjusted (r = 0.61; p = 0.047; and r = 0.69; p = 0.02), respectively), and after adjustment for changes in body mass index (r = 0.63; p = 0.049; and r = 0.73; p = 0.02), respectively). Changes in relative abundance of Clostridium asparagiforme were associated with the reduction in total severe hot flashes (r = 0.69; p = 0.019) and severe night hot flashes (r = 0.82; p = 0.002) and the latter association remained significant after adjustment for changes in body mass index (r = 0.75; p = 0.01).

CONCLUSIONS

This exploratory analysis revealed potential associations between changes in vasomotor symptoms in response to a diet change and changes in the gut microbiome. Larger randomized clinical trials are needed to investigate these findings.

Why Bufo gargarizans tadpoles grow bigger in Pb-contaminated environments? The gut microbiota matter

The impacts of lead/Pb2+ on ecosystems have received widespread attention. Growth suppression is a major toxic effect of Pb compounds on aquatic animals, however, some studies have also reported their growth-promoting effects. These complex outcomes may be explained by anions that accompany Pb2+ or by the multiple toxic mechanisms/pathways of Pb2+. To examine these hypotheses, we tested how Bufo gargarizans tadpoles responded to Pb(NO3)2 (100 and 200 μg/L Pb2+) using transcriptomics and microbiomics, with NaNO3 and blank groups as controls. Tadpoles exposed to Pb(NO3)2 showed delayed development while increased somatic growth in a dose-dependent manner, which can be attributed to the effects of NO3- and Pb2+, respectively. Tadpole transcriptomics revealed that exposure to NO3- downregulated the MAPK pathway at transcriptional level, explaining the development-suppressing effect of NO3-; while Pb2+ upregulated the transcription of detoxification pathways (e.g., xenobiotics metabolism by cytochrome P450 and glutathione metabolism), indicating cellular stress and thus contradicting the growth advantage of Pb2+-exposed tadpoles. Pb2+ exposure changed the tadpole gut microbiota drastically, characterized by increased polysaccharides and carbohydrate utilization while decreased fatty acid and amino acid consumption according to microbial functional analysis. Similar gut microbial variations were observed in field-collected tadpoles from different Pb2+ environments. This metabolic shift in gut microbiota likely improved the overall food utilization efficiency and increased the allocation of fatty acids and amino acids to the host, explaining the growth advantage of Pb2+-exposed tadpoles. In summary, our results suggest multiple toxic pathways of Pb2+, and the gut microbiota may affect the pollution outcomes on animals.

Yak milk protects against alcohol-induced liver injury in rats

The protective effects of yak milk (YM) against chronic alcoholic liver injury in rats were investigated in this study. Histologic and biochemical analyses demonstrated that YM consumption ameliorates alcohol-induced liver injury by increasing the liver antioxidant enzyme activity and reducing inflammation. Furthermore, microbiome and metabolomic analyses exploring YM's impact on gut microbiota and metabolism found that YM administration regulates gut microbiota composition. Specifically, there was a decrease in the relative abundance of Helicobacter, Streptococcus, Peptococcus and Tyzzerella, along with an increase in Turisibacter and Intestinimonas. Moreover, Pearson analysis indicated positive correlations between Peptococcus and Tyzzerella with ALT and AST levels, while showing a negative correlation with ADH levels. Furthermore, differential metabolite analysis of fecal samples from the YM group identified significant increases in the taurine (2-Aminoethanesulfonic acid), hypotaurine (2-Aminoethanesulfonic Acid) and isethionic acid levels. Finally, KEGG topology analysis highlighted taurine and hypotaurine metabolism as the primary pathways influenced by YM intervention. Therefore, these findings collectively suggest that YM may protect alcohol-exposed rats against liver injury by modulating oxidative stress, inflammatory response, gut microbiota disorder, and metabolic regulation.

Synergistic Responses of Tibetan Sheep Rumen Microbiota, Metabolites, and the Host to the Plateau Environment

Plateau adaptation in animals involves genetic mechanisms as well as coevolutionary mechanisms of the microbiota and metabolome of the animal. Therefore, the characteristics of the rumen microbiome and metabolome, transcriptome, and serum metabolome of Tibetan sheep at different altitudes (4500 m, 3500 m, and 2500 m) were analyzed. The results showed that the rumen differential metabolites at 3500 m and 4500 m were mainly enriched in amino acid metabolism, lipid metabolism, and carbohydrate metabolism, and there was a significant correlation with microbiota. The differentially expressed genes and metabolites at middle and high altitudes were coenriched in asthma, arachidonic acid metabolism, and butanoate and propanoate metabolism. In addition, the serum differential metabolites at 3500 m and 4500 m were mainly enriched in amino acid metabolism, lipid metabolism, and metabolism of xenobiotics by cytochrome P450, and they were also related to microbiota. Further analysis revealed that rumen metabolites accounted for 7.65% of serum metabolites. These common metabolites were mainly enriched in metabolic pathways and were significantly correlated with host genes (p < 0.05). This study found that microbiota, metabolites, and epithelial genes were coenriched in pathways related to lipid metabolism, energy metabolism, and immune metabolism, which may be involved in the regulation of Tibetan sheep adaptation to plateau environmental changes.

Contribution of the microbiome for better phenotyping of people living with obesity

Obesity has reached epidemic proportion worldwide and in all ages. Available evidence points to a multifactorial pathogenesis involving gene predisposition and environmental factors. Gut microbiota plays a critical role as a major interface between external factors, i.e., diet, lifestyle, toxic chemicals, and internal mechanisms regulating energy and metabolic homeostasis, fat production and storage. A shift in microbiota composition is linked with overweight and obesity, with pathogenic mechanisms involving bacterial products and metabolites (mainly endocannabinoid-related mediators, short-chain fatty acids, bile acids, catabolites of tryptophan, lipopolysaccharides) and subsequent alterations in gut barrier, altered metabolic homeostasis, insulin resistance and chronic, low-grade inflammation. Although animal studies point to the links between an "obesogenic" microbiota and the development of different obesity phenotypes, the translational value of these results in humans is still limited by the heterogeneity among studies, the high variation of gut microbiota over time and the lack of robust longitudinal studies adequately considering inter-individual confounders. Nevertheless, available evidence underscores the existence of several genera predisposing to obesity or, conversely, to lean and metabolically health phenotype (e.g., Akkermansia muciniphila, species from genera Faecalibacterium, Alistipes, Roseburia). Further longitudinal studies using metagenomics, transcriptomics, proteomics, and metabolomics with exact characterization of confounders are needed in this field. Results must confirm that distinct genera and specific microbial-derived metabolites represent effective and precision interventions against overweight and obesity in the long-term.

Dietary Macleaya cordata extract supplementation improves the growth performance and gut health of broiler chickens with necrotic enteritis

BACKGROUND

The poultry industry needs effective antibiotic alternatives to control outbreaks of necrotic enteritis (NE) caused by Clostridium perfringens.

METHODS

The aim of this study was to investigate the effects of dietary supplementation with Macleaya cordata extract (MCE) on the immune function and gut microbiota of broilers with NE. A total of 288 1-day-old broiler chicks were randomly assigned to a 2 × 2 factorial arrangement with two concentrations of dietary MCE supplementation (0 or 350 mg/kg of diet) and two disease challenge statuses (control or NE).

RESULTS

The results revealed that NE significantly increased the feed conversion rate (FCR), mortality, intestinal lesion score, the levels of IL-1β, IL-17 and IFN-γ/IL-4 in serum and IL-17/IL-10 in the jejunal mucosa, mRNA levels of TLR2, IFN-γ and pIgR in the jejunum, and Clostridium perfringens concentrations in the cecum. NE significantly decreased the body weight (BW), body weight gain (BWG), jejunal villus height, V/C, mRNA level of AMPK-α1 in jejunum, IL-4 level in the jejunal mucosa and lactic acid bacteria abundance in the cecum. MCE significantly increased BW, BWG, jejunal villus height, V/C, mRNA levels of occludin, ZO-1 and AMPK-α1 in the jejunum, the levels of IgA and IgG in serum and IL-10 in the jejunal mucosa and mRNA levels of NF-κB, IL-10 and MHC-II in the jejunum. Additionally, MCE significantly decreased the FCR, mortality, intestinal lesion score, jejunal crypt depth, the levels of IFN-γ and IL-17 in serum and IL-17/IL-10 in the jejunal mucosa, Clostridium perfringens concentrations in the cecum, and mRNA levels of IL-17/IL-10 in the jejunum. Moreover, NE significantly increased the abundance of bacteria that are associated with inflammation, obesity and depression (Alistipes, Barnesiella, Intestinimonas, RF39 and UCG-005) and significantly decreased the abundance of short-chain fatty acid (SCFA)-producing bacteria (Anaerotruncus, Butyricicoccus and Bacteroides) in the cecum. MCE significantly increased the abundance of SCFA-producing bacteria (Streptococcus, Ruminococcus_torques_group and Lachnospiraceae_NK4A136_group) and significantly reduced the abundance of bacteria that are associated with inflammation and obesity (Alistipes, Barnesiella and UCG-010) in the cecum. In the cecum of broilers with NE, the relative abundance of Barnesiella and Alistipes was higher and that of Lachnoclostridium and Shuttleworthia was lower. Interestingly, these trends were reversed by the addition of MCE to the diet. Spearman correlation analysis showed that Barnesiella and Alistipes were associated with enhanced intestinal inflammation and inhibited growth performance, whereas Lachnoclostridium and Shuttleworthia were associated with anti-inflammatory effects.

CONCLUSIONS

MCE ameliorated the loss of growth performance in broiler chickens with NE, probably by regulating the intestinal barrier, immune function, and gut microbiota.

The Pathogenicity of Fusobacterium nucleatum Modulated by Dietary Fibers-A Possible Missing Link between the Dietary Composition and the Risk of Colorectal Cancer

The dietary composition has been approved to be strongly associated with the risk of colorectal cancer (CRC), one of the most serious malignancies worldwide, through regulating the gut microbiota structure, thereby influencing the homeostasis of colonic epithelial cells by producing carcinogens, i.e., ammonia or antitumor metabolites, like butyrate. Though butyrate-producing Fusobacterium nucleatum has been considered a potential tumor driver associated with chemotherapy resistance and poor prognosis in CRC, it was more frequently identified in the gut microbiota of healthy individuals rather than CRC tumor tissues. First, within the concentration range tested, the fermentation broth of F. nucleatum exhibited no significant effects on Caco-2 and NCM460 cells viability except for a notable up-regulation of the expression of TLR4 (30.70%, p < 0.0001) and Myc (47.67%, p = 0.021) and genes encoding proinflammatory cytokines including IL1B (197.57%, p < 0.0001), IL6 (1704.51%, p < 0.0001), and IL8 (897.05%, p < 0.0001) in Caco-2 cells exclusively. Although no marked effects of polydextrose or fibersol-2 on the growth of F. nucleatum, Caco-2 and NCM460 cells were observed, once culture media supplemented with polydextrose or fibersol-2, the corresponding fermentation broths of F. nucleatum significantly inhibited the growth of Caco-2 cells up to 48.90% (p = 0.0003, 72 h, 10%) and 52.96% (p = 0.0002, 72 h, 10%), respectively in a dose-dependent manner. These two kinds of fibers considerably promoted butyrate production of F. nucleatum up to 205.67% (p < 0.0001, 6% polydextrose at 24 h) and 153.46% (p = 0.0002, 6% fibersol-2 at 12 h), which explained why and how the fermentation broths of F. nucleatum cultured with fibers suppressing the growth of Caco-2 cells. Above findings indicated that dietary fiber determined F. nucleatum to be a carcinogenic or antitumor bacterium, and F. nucleatum played an important role in the association between the dietary composition, primarily the content of dietary fibers, and the risk of CRC.

Investigating causal associations among gut microbiota, metabolites, and liver diseases: a Mendelian randomization study

Objective

There is some evidence for an association between gut microbiota and nonalcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), and viral hepatitis, but no studies have explored their causal relationship.

Methods

Instrumental variables of the gut microbiota (N = 13266) and gut microbiota-derived metabolites (N = 7824) were acquired, and a Mendelian randomization study was performed to explore their influence on NAFLD (1483 European cases and 17,781 European controls), ALD (2513 European cases and 332,951 European controls), and viral hepatitis risk (1971 European cases and 340,528 European controls). The main method for examining causality is inverse variance weighting (IVW).

Results

IVW results confirmed that Anaerotruncus (p = 0.0249), Intestinimonas (p = 0.0237), Lachnoclostridium (p = 0.0245), Lachnospiraceae NC2004 group (p = 0.0083), Olsenella (p = 0.0163), and Peptococcus (p = 0.0472) were protective factors for NAFLD, and Ruminococcus 1 (p = 0.0120) was detrimental for NAFLD. The higher abundance of three genera, Lachnospira (p = 0.0388), Desulfovibrio (p = 0.0252), and Ruminococcus torques group (p = 0.0364), was correlated with a lower risk of ALD, while Ruminococcaceae UCG 002 level was associated with a higher risk of ALD (p = 0.0371). The Alistipes (p = 0.0069) and Ruminococcaceae NK4A214 group (p = 0.0195) were related to a higher risk of viral hepatitis. Besides, alanine (p = 0.0076) and phenyllactate (p = 0.0100) were found to be negatively correlated with NAFLD, while stachydrine (Op = 0.0244) was found to be positively associated with NAFLD. The phenylacetate (p = 0.0353) and ursodeoxycholate (p = 0.0144) had a protective effect on ALD, while the threonate (p = 0.0370) exerted a detrimental influence on ALD. The IVW estimates of alanine (p = 0.0408) and cholate (p = 0.0293) showed their suggestive harmful effects against viral hepatitis, while threonate (p = 0.0401) displayed its suggestive protective effect against viral hepatitis.

Conclusion

In conclusion, our research supported causal links between the gut microbiome and its metabolites and NAFLD, ALD, and viral hepatitis.

Mechanisms of action of coffee bioactive compounds - a key to unveil the coffee paradox

The knowledge of the relationship between the chemical structure of food components with their mechanisms of action is crucial for the understanding of diet health benefits. This review relates the chemical variability present in coffee beverages with the mechanisms involved in key physiological events, supporting coffee as a polyvalent functional food. Coffee intake has been related with several health-promoting properties such as neuroprotective (caffeine, chlorogenic acids and melanoidins), anti-inflammatory (caffeine, chlorogenic acids, melanoidins, diterpenes), microbiota modulation (polysaccharides, melanoidins, chlorogenic acids), immunostimulatory (polysaccharides), antidiabetic (trigonelline, chlorogenic acids), antihypertensive (chlorogenic acids) and hypocholesterolemic (polysaccharides, chlorogenic acids, lipids). Nevertheless, caffeine and diterpenes are coffee components with ambivalent effects on health. Additionally, a large range of potentially harmful compounds, including acrylamide, hydroxymethylfurfural, furan, and advanced glycation end products, are formed during the roasting of coffee and are present in the beverages. However, coffee beverages are part of the daily human dietary healthy habits, configuring a coffee paradox.

Advanced Glycation End Products (AGEs) in Diet and Skin in Relation to Stool Microbiota: The Rotterdam Study

BACKGROUND

Advanced glycation end products (AGEs) are involved in age-related diseases, but the interaction of gut microbiota with dietary AGEs (dAGEs) and tissue AGEs in the population is unknown.

OBJECTIVE

Our objective was to investigate the association of dietary and tissue AGEs with gut microbiota in the population-based Rotterdam Study, using skin AGEs as a marker for tissue accumulation and stool microbiota as a surrogate for gut microbiota.

DESIGN

Dietary intake of three AGEs (dAGEs), namely carboxymethyl-lysine (CML), N-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MGH1), and carboxyethyl-lysine (CEL), was quantified at baseline from food frequency questionnaires. Following up after a median of 5.7 years, skin AGEs were measured using skin autofluorescence (SAF), and stool microbiota samples were sequenced (16S rRNA) to measure microbial composition (including alpha-diversity, beta-dissimilarity, and taxonomic abundances) as well as predict microbial metabolic pathways. Associations of both dAGEs and SAF with microbial measures were investigated using multiple linear regression models in 1052 and 718 participants, respectively.

RESULTS

dAGEs and SAF were not associated with either the alpha-diversity or beta-dissimilarity of the stool microbiota. After multiple-testing correction, dAGEs were not associated with any of the 188 genera tested, but were nominally inversely associated with the abundance of Barnesiella, Colidextribacter, Oscillospiraceae UCG-005, and Terrisporobacter, in addition to being positively associated with Coprococcus, Dorea, and Blautia. A higher abundance of Lactobacillus was associated with a higher SAF, along with several nominally significantly associated genera. dAGEs and SAF were nominally associated with several microbial pathways, but none were statistically significant after multiple-testing correction.

CONCLUSIONS

Our findings did not solidify a link between habitual dAGEs, skin AGEs, and overall stool microbiota composition. Nominally significant associations with several genera and functional pathways suggested a potential interaction between gut microbiota and AGE metabolism, but validation is required. Future studies are warranted, to investigate whether gut microbiota modifies the potential impact of dAGEs on health.

Gut Microbial Metabolite Butyrate and Its Therapeutic Role in Inflammatory Bowel Disease: A Literature Review

Background and objective: Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic inflammatory disorder characterized by aberrant immune responses and compromised barrier function in the gastrointestinal tract. IBD is associated with altered gut microbiota and their metabolites in the colon. Butyrate, a gut microbial metabolite, plays a crucial role in regulating immune function, epithelial barrier function, and intestinal homeostasis. In this review, we aim to present an overview of butyrate synthesis and metabolism and the mechanism of action of butyrate in maintaining intestinal homeostasis and to discuss the therapeutic implications of butyrate in IBD. Methods: We searched the literature up to March 2023 through PubMed, Web of Science, and other sources using search terms such as butyrate, inflammation, IBD, Crohn's disease, and ulcerative colitis. Clinical studies in patients and preclinical studies in rodent models of IBD were included in the summary of the therapeutic implications of butyrate. Results: Research in the last two decades has shown the beneficial effects of butyrate on gut immune function and epithelial barrier function. Most of the preclinical and clinical studies have shown the positive effect of butyrate oral supplements in reducing inflammation and maintaining remission in colitis animal models and IBD patients. However, butyrate enema showed mixed effects. Butyrogenic diets, including germinated barley foodstuff and oat bran, are found to increase fecal butyrate concentrations and reduce the disease activity index in both animal models and IBD patients. Conclusions: The current literature suggests that butyrate is a potential add-on therapy to reduce inflammation and maintain IBD remission. Further clinical studies are needed to determine if butyrate administration alone is an effective therapeutic treatment for IBD.

Gut-liver axis: barriers and functional circuits

The gut and the liver are characterized by mutual interactions between both organs, the microbiome, diet and other environmental factors. The sum of these interactions is conceptualized as the gut-liver axis. In this Review we discuss the gut-liver axis, concentrating on the barriers formed by the enterohepatic tissues to restrict gut-derived microorganisms, microbial stimuli and dietary constituents. In addition, we discuss the establishment of barriers in the gut and liver during development and their cooperative function in the adult host. We detail the interplay between microbial and dietary metabolites, the intestinal epithelium, vascular endothelium, the immune system and the various host soluble factors, and how this interplay establishes a homeostatic balance in the healthy gut and liver. Finally, we highlight how this balance is disrupted in diseases of the gut and liver, outline the existing therapeutics and describe the cutting-edge discoveries that could lead to the development of novel treatment approaches.

The Implication of Short-Chain Fatty Acids in Obesity and Diabetes

Evidence indicates that short-chain fatty acids (SCFAs) generated from the gut microbiota play crucial roles in host metabolism. They contribute to metabolic regulation and energy acquisition of the host by influencing the development of metabolic disorders. This review aims to synthesize recent advances from the literature to investigate the implication of SCFAs in the modulation of obesity and diabetes pathologies. For a better understanding of the relationships between SCFAs and host metabolism, we need to answer some questions: What is the biochemistry of SCFAs, and how they are generated by gut microbiota? What are the bacteria producing of SCFAs and from which routes? How SCFAs are absorbed and transported in the gut by different mechanisms and receptors? How SCFAs involved in obesity and diabetes pathologies?

The Interaction between Gut Microbiota and Host Amino Acids Metabolism in Multiple Myeloma

Although novel therapies have dramatically improved outcomes for multiple myeloma (MM) patients, relapse is inevitable and overall outcomes are heterogeneous. The gut microbiota is becoming increasingly recognized for its influence on host metabolism. To date, evidence has suggested that the gut microbiota contributes to MM, not only via the progressive activities of specific bacteria but also through the influence of the microbiota on host metabolism. Importantly, the abnormal amino acid metabolism, as well as the altered microbiome in MM, is becoming increasingly apparent, as is the influence on MM progression and the therapeutic response. Moreover, the gut-microbiota-host-amino-acid metabolism interaction in the progression of MM has been highlighted. Modulation of the gut microbiota (such as fecal microbiota transplantation, FMT) can be modified, representing a new angle in MM treatment that can improve outcomes. In this review, the relationship between gut microbiota, metabolism, and MM, together with strategies to modulate the microbiota, will be discussed, and some unanswered questions for ongoing and future research will be presented.

Inflammatory Responses Induced by the Monophasic Variant of Salmonella Typhimurium in Pigs Play a Role in the High Shedder Phenotype and Fecal Microbiota Composition

Pigs infected with Salmonella may excrete large amounts of Salmonella, increasing the risk of spread of this pathogen in the food chain. Identifying Salmonella high shedder pigs is therefore required to mitigate this risk. We analyzed immune-associated markers and composition of the gut microbiota in specific-pathogen-free pigs presenting different shedding levels after an oral infection with Salmonella. Immune response was studied through total blood cell counts, production of anti-Salmonella antibodies and cytokines, and gene expression quantification. Total Salmonella shedding for each pig was estimated and hierarchical clustering was used to cluster pigs into high, intermediate, and low shedders. Gut microbiota compositions were assessed using 16S rRNA microbial community profiling. Comparisons were made between control and inoculated pigs, then between high and low shedders pigs. Prior to infection, high shedders had similar immunological profiles compared to low shedders. As soon as 1 day postinoculation (dpi), significant differences on the cytokine production level and on the expression level of several host genes related to a proinflammatory response were observed between high and low shedders. Infection with Salmonella induced an early and profound remodeling of the immune response in all pigs, but the intensity of the response was stronger in high shedders. In contrast, low shedders seroconverted earlier than high shedders. Just after induction of the proinflammatory response (at 2 dpi), some taxa of the fecal microbiota were specific to the shedding phenotypes. This was related to the enrichment of several functional pathways related to anaerobic respiration in high shedders. In conclusion, our data show that the immune response to Salmonella modifies the fecal microbiota and subsequently could be responsible for shedding phenotypes. Influencing the gut microbiota and reducing intestinal inflammation could be a strategy for preventing Salmonella high shedding in livestock. IMPORTANCE Salmonellosis remains the most frequent human foodborne zoonosis after campylobacteriosis and pork meat is considered one of the major sources of human foodborne infections. At the farm, host heterogeneity in pig infection is problematic. High Salmonella shedders contribute more significantly to the spread of this foodborne pathogen in the food chain. The identification of predictive biomarkers for high shedders could help to control Salmonella in pigs. The purpose of the present study was to investigate why some pigs become super shedders and others low shedders. We thus investigated the differences in the fecal microbial composition and the immune response in orally infected pigs presenting different Salmonella shedding patterns. Our data show that the proinflammatory response induced by S. Typhimurium at 1 dpi could be responsible for the modification of the fecal microbiota composition and functions observed mainly at 2 and 3 dpi and to the low and super shedder phenotypes.

The Maillard reaction end product Nε-carboxymethyllysine is metabolized in humans and the urinary levels of the microbial metabolites are associated with individual diet

During food processing most of the thermally-driven chemical reactions start off on the side chain amino group of lysine generating structurally modified compounds with specific metabolic routes. Upon human digestion, dietary N^ε-carboxymethyllysine (CML) may enter the colon and undergo gut microbial metabolism. However, little is known about the in vivo metabolic fate of dietary CML and its relationship with the habitual diet. We explored by hydrophilic interaction liquid chromatography tandem mass spectrometry the metabolites of CML in urine samples collected from 46 healthy subjects and studied the associations with diet. Mean concentration of N-carboxymethylcadaverine (CM-CAD), N-carboxymethylaminopentanoic acid (CM-APA), N-carboxymethylaminopentanol (CM-APO), and the N-carboxymethyl-Δ1-piperideinium ion were 0.49 nmol mg^-1 creatinine, 1.45 nmol mg^-1 creatinine, 4.43 nmol mg^-1 creatinine and 4.79 nmol mg^-1 creatinine, respectively. The urinary concentration of CML, its metabolites and lysine were positively correlated. Dietary intake of meat products negatively correlated with urinary excretion of CML and CM-APA; conversely dietary plant-to-animal proteins ratio positively correlated with urinary CML and its metabolites. The identification and quantification of CML metabolites in urine and the associations with diet corroborate the hypothesis that CML, an advanced glycation end-product, can undergo further biochemical transformations in vivo. The gut microbiome may have a major role in human metabolism of dietary CML.

Consistent Stool Metagenomic Biomarkers Associated with the Response To Melanoma Immunotherapy

The human gut microbiome plays an important role in both health and disease. Recent studies have demonstrated a strong influence of the gut microbiome composition on the efficacy of cancer immunotherapy. However, available studies have not yet succeeded in finding reliable and consistent metagenomic markers that are associated with the response to immunotherapy. Therefore, the reanalysis of the published data may improve our understanding of the association between the composition of the gut microbiome and the treatment response. In this study, we focused on melanoma-related metagenomic data, which are more abundant than are data from other tumor types. We analyzed the metagenomes of 680 stool samples from 7 studies that were published earlier. The taxonomic and functional biomarkers were selected after comparing the metagenomes of patients showing different treatment responses. The list of selected biomarkers was also validated on additional metagenomic data sets that were dedicated to the influence of fecal microbiota transplantation on the response to melanoma immunotherapy. According to our analysis, the resulting cross-study taxonomic biomarkers included three bacterial species: Faecalibacterium prausnitzii, Bifidobacterium adolescentis, and Eubacterium rectale. 101 groups of genes were identified to be functional biomarkers, including those potentially involved in the production of immune-stimulating molecules and metabolites. Moreover, we ranked the microbial species by the number of genes encoding functionally relevant biomarkers that they contained. Thus, we put together a list of potentially the most beneficial bacteria for immunotherapy success. F. prausnitzii, E. rectale, and three species of bifidobacteria stood out as the most beneficial species, even though some useful functions were also present in other bacterial species. IMPORTANCE In this study, we put together a list of potentially the most beneficial bacteria that were associated with a responsiveness to melanoma immunotherapy. Another important result of this study is the list of functional biomarkers of responsiveness to immunotherapy, which are dispersed among different bacterial species. This result possibly explains the existing irregularities between studies regarding the bacterial species that are beneficial to melanoma immunotherapy. Overall, these findings can be utilized to issue recommendations for gut microbiome correction in cancer immunotherapy, and the resulting list of biomarkers might serve as a good stepping stone for the development of a diagnostic test that is aimed at predicting patients' responses to melanoma immunotherapy.

Butyrate's role in human health and the current progress towards its clinical application to treat gastrointestinal disease

Butyrate is a key energy source for colonocytes and is produced by the gut microbiota through fermentation of dietary fiber. Butyrate is a histone deacetylase inhibitor and also signals through three G-protein coupled receptors. It is clear that butyrate has an important role in gastrointestinal health and that butyrate levels can impact both host and microbial functions that are intimately coupled with each other. Maintaining optimal butyrate levels improves gastrointestinal health in animal models by supporting colonocyte function, decreasing inflammation, maintaining the gut barrier, and promoting a healthy microbiome. Butyrate has also shown protective actions in the context of intestinal diseases such as inflammatory bowel disease, graft-versus-host disease of the gastrointestinal tract, and colon cancer, whereas lower levels of butyrate and/or the microbes which are responsible for producing this metabolite are associated with disease and poorer health outcomes. However, clinical efforts to increase butyrate levels in humans and reverse these negative outcomes have generated mixed results. This article discusses our current understanding of the molecular mechanisms of butyrate action with a focus on the gastrointestinal system, the links between host and microbial factors, and the efforts that are currently underway to apply the knowledge gained from the bench to bedside.

Butyrate producers, "The Sentinel of Gut": Their intestinal significance with and beyond butyrate, and prospective use as microbial therapeutics

Gut-microbial butyrate is a short-chain fatty acid (SCFA) of significant physiological importance than the other major SCFAs (acetate and propionate). Most butyrate producers belong to the Clostridium cluster of the phylum Firmicutes, such as Faecalibacterium, Roseburia, Eubacterium, Anaerostipes, Coprococcus, Subdoligranulum, and Anaerobutyricum. They metabolize carbohydrates via the butyryl-CoA: acetate CoA-transferase pathway and butyrate kinase terminal enzymes to produce most of butyrate. Although, in minor fractions, amino acids can also be utilized to generate butyrate via glutamate and lysine pathways. Butyrogenic microbes play a vital role in various gut-associated metabolisms. Butyrate is used by colonocytes to generate energy, stabilizes hypoxia-inducible factor to maintain the anaerobic environment in the gut, maintains gut barrier integrity by regulating Claudin-1 and synaptopodin expression, limits pro-inflammatory cytokines (IL-6, IL-12), and inhibits oncogenic pathways (Akt/ERK, Wnt, and TGF-β signaling). Colonic butyrate producers shape the gut microbial community by secreting various anti-microbial substances, such as cathelicidins, reuterin, and β-defensin-1, and maintain gut homeostasis by releasing anti-inflammatory molecules, such as IgA, vitamin B, and microbial anti-inflammatory molecules. Additionally, butyrate producers, such as Roseburia, produce anti-carcinogenic metabolites, such as shikimic acid and a precursor of conjugated linoleic acid. In this review, we summarized the significance of butyrate, critically examined the role and relevance of butyrate producers, and contextualized their importance as microbial therapeutics.

Supplemental N-acyl homoserine lactonase alleviates intestinal disruption and improves gut microbiota in broilers challenged by Salmonella Typhimurium

BACKGROUND

Salmonella Typhimurium challenge causes a huge detriment to chicken production. N-acyl homoserine lactonase (AHLase), a quorum quenching enzyme, potentially inhibits the growth and virulence of Gram-negative bacteria. However, it is unknown whether AHLase can protect chickens against S. Typhimurium challenge. This study aimed to evaluate the effects of AHLase on growth performance and intestinal health in broilers challenged by S. Typhimurium. A total of 240 one-day-old female crossbred broilers (817C) were randomly divided into 5 groups (6 replicates/group): negative control (NC), positive control (PC), and PC group supplemented with 5, 10 or 20 U/g AHLase. All birds except those in NC were challenged with S. Typhimurium from 7 to 9 days of age. All parameters related to growth and intestinal health were determined on d 10 and 14.

RESULTS

The reductions (P < 0.05) in body weight (BW) and average daily gain (ADG) in challenged birds were alleviated by AHLase addition especially at 10 U/g. Thus, samples from NC, PC and PC plus 10 U/g AHLase group were selected for further analysis. S. Typhimurium challenge impaired (P < 0.05) intestinal morphology, elevated (P < 0.05) ileal inflammatory cytokines (IL-1β and IL-8) expression, and increased (P < 0.05) serum diamine oxidase (DAO) activity on d 10. However, AHLase addition normalized these changes. Gut microbiota analysis on d 10 showed that AHLase reversed the reductions (P < 0.05) in several beneficial bacteria (e.g. Bacilli, Bacillales and Lactobacillales), along with increases (P < 0.05) in certain harmful bacteria (e.g. Proteobacteria, Gammaproteobacteria, Enterobacteriaceae and Escherichia/Shigella) in PC group. Furthermore, AHLase-induced increased beneficial bacteria and decreased harmful bacteria were basically negatively correlated (P < 0.05) with the reductions of ileal IL-1β and IL-8 expression and serum DAO activity, but positively correlated (P < 0.05) with the increased BW and ADG. Functional prediction revealed that AHLase abolished S. Typhimurium-induced upregulations (P < 0.05) of certain pathogenicity-related pathways such as lipopolysaccharide biosynthesis, shigellosis, bacterial invasion of epithelial cells and pathogenic Escherichia coli infection of gut microbiota.

CONCLUSIONS

Supplemental AHLase attenuated S. Typhimurium-induced growth retardation and intestinal disruption in broilers, which could be associated with the observed recovery of gut microbiota dysbiosis.

Implication of gut microbes and its metabolites in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer with a significant impact on loss of life. In 2020, nearly 1.9 million new cases and over 9,35,000 deaths were reported. Numerous microbes that are abundant in the human gut benefit host physiology in many ways. Although the underlying mechanism is still unknown, their association appears to be crucial in the beginning and progression of CRC. Diet has a significant impact on the microbial composition and may increase the chance of getting CRC. Increasing evidence points to the gut microbiota as the primary initiator of colonic inflammation, which is connected to the development of colonic tumors. However, it is unclear how the microbiota contributes to the development of CRCs. Patients with CRC have been found to have dysbiosis of the gut microbiota, which can be identified by a decline in commensal bacterial species, such as those that produce butyrate, and a concurrent increase in harmful bacterial populations, such as opportunistic pathogens that produce pro-inflammatory cytokines. We believe that using probiotics or altering the gut microbiota will likely be effective tools in the fight against CRC treatment.

PURPOSE

In this review, we revisited the association between gut microbiota and colorectal cancer whether cause or effect. The various factors which influence gut microbiome in patients with CRC and possible mechanism in relation with development of CRC.

CONCLUSION

The clinical significance of the intestinal microbiota may aid in the prevention and management of CRC.

Microbiome and Metabolomics in Liver Cancer: Scientific Technology

Primary liver cancer is a heterogeneous disease. Liver cancer metabolism includes both the reprogramming of intracellular metabolism to enable cancer cells to proliferate inappropriately and adapt to the tumor microenvironment and fluctuations in regular tissue metabolism. Currently, metabolomics and metabolite profiling in liver cirrhosis, liver cancer, and hepatocellular carcinoma (HCC) have been in the spotlight in terms of cancer diagnosis, monitoring, and therapy. Metabolomics is the global analysis of small molecules, chemicals, and metabolites. Metabolomics technologies can provide critical information about the liver cancer state. Here, we review how liver cirrhosis, liver cancer, and HCC therapies interact with metabolism at the cellular and systemic levels. An overview of liver metabolomics is provided, with a focus on currently available technologies and how they have been used in clinical and translational research. We also list scalable methods, including chemometrics, followed by pathway processing in liver cancer. We conclude that important drivers of metabolomics science and scientific technologies are novel therapeutic tools and liver cancer biomarker analysis.

Dietary supplementation of ferrous glycinate improves intestinal barrier function by modulating microbiota composition in Cherry Valley ducks

Ferrous glycinate (Fe-Gly) has been increasingly used as iron fortification in the diets of weaned piglets and broilers, but the effect of Fe-Gly on intestinal barrier function in meat ducks has not been well defined. This study therefore investigated the effect of Fe-Gly on apparent nutrient utilization, hematological indices, intestinal morphological parameters, intestinal barrier function and microbial composition in meat ducks. A total of 672 one-day-old Cherry Valley ducks were randomly divided into 6 treatments (8 replicates for each treatment and 14 ducks for each replicate) and fed diets with 0 (control), 30, 60, 90 and 120 mg/kg Fe-Gly or 120 mg/kg FeSO₄ for 35 d. The results showed that diets supplemented with Fe-Gly significantly increased average daily gain (ADG), average daily feed intake (ADFI), hematocrit (HCT), mean cell volume (MCV), the apparent utilization of dry matter (DM) and metabolizable energy (ME), villus height (VH) and villus height-to-crypt depth ratio (V:C) (P < 0.05). Fe-Gly also significantly up-regulated barrier-related genes including zonula occludens-1 (ZO-1), zonula occludens-2 (ZO-2), mucin 2 (MUC2) and lysozyme (LYZ) (P < 0.05), and down-regulated the mRNA expression of claudin-2 (CLDN2) and occludin (OCLN) in the jejunum (P < 0.05). The 16S rRNA sequence analysis indicated that the diet with Fe-Gly had a higher relative abundance of Intestinimonas and Romboutsia (P < 0.05), which have an ability to produce short chain fatty acids (SCFAs), especially butyric acid. It also decreased the relative abundance of pathobiont, including Megamonas, Eubacterium_coprostanoligenes_group and Plebeius (P < 0.05). Additionally, diets supplemented with 120 mg/kg Fe-Gly significantly increased the apparent utilization of DM and ME (P < 0.05) and decreased the relative abundance of Megamonas_unclassified and Bacteroides_unclassified compared with those fed 120 mg/kg FeSO₄ (P < 0.05). These results revealed that diets supplemented with Fe-Gly exerted a potent beneficial effect on physical, chemical, immune and microbial barriers, thereby improving the integrity of the intestinal structure, promoting the digestion and absorption of nutrients to a certain extent, and ultimately elevating the growth performance of ducks.

Hepatic metabolism gene expression and gut microbes in offspring, subjected to in-utero PFOS exposure and postnatal diet challenges

We examined the changes in hepatic metabolic gene expression and gut microbiota of offspring exposed to PFOS in-utero. At GD17.5, our data showed that PFOS exposure decreased fetal bodyweights and hepatic metabolic gene expressions but increased relative liver mass and lipid accumulation. At PND21, in-utero high-dose PFOS-exposed offspring exhibited significantly greater bodyweight (catch-up-growth), associated with significant induction of hepatic metabolic gene expression. In addition, 16SrRNA-sequencing of the cecal samples revealed an increase in carbohydrate catabolism but a reduction in microbial polysaccharide synthesis and short-chain fatty acid (SCFA) metabolism. From PND21-80, a postnatal diet-challenge for the offspring was conducted. At PND80 under a normal diet, in-utero high-dose PFOS-exposed offspring maintained the growth "catch-up" effect. In contrast, in a high-fat-diet, the bodyweight of in-utero high-dose PFOS-exposed adult offspring were significantly lesser than the corresponding low-dose and control groups. Even though in the high-fat-diet, the in-utero PFOS-exposed adult offspring showed significant upregulation of hepatic metabolic genes, the lower bodyweight suggests that they had difficulty utilizing high-fat nutrients. Noteworthy, the metagenomic data showed a significant reduction in the biosynthesis of microbial polysaccharides, vitamin B, and SCFAs in the PFOS-exposed adult offspring. Furthermore, the observed effects were significantly reduced in the PFOS-exposed adult offspring with the high-fat diet but supplemented with sucrose. Our study demonstrated that in-utero PFOS exposure caused inefficient fat metabolism and increased the risk of hepatic steatosis in offspring.

Differences in gut microbial fructoselysine degradation activity between breast-fed and formula-fed infants

The Amadori product fructoselysine is formed upon heating of food products and is abundantly present in infant formula while being almost absent in breast milk. The human gut microbiota can degrade fructoselysine for which interindividual differences have been described for adults. The aim of this study is to compare functional differences in microbial fructoselysine degradation between breast-fed and formula-fed infants, in view of their different diets and resulting different fructoselysine exposures. First, a publicly available metagenomic dataset with metagenome-assembled genomes (MAGs) from infant fecal samples was analyzed and showed that query genes involved in fructoselysine degradation (frlD/yhfQ) were abundantly present in multiple bacterial taxa in the fecal samples, with a higher prevalence in the formula-fed infants. Next, fecal samples collected from exclusively breast-fed and formula-fed infants were anaerobically incubated with fructoselysine. Both groups degraded fructoselysine, however the fructoselysine degradation activity was significantly higher by fecal samples from formula-fed infants. Overall, this study provides evidence that infant formula feeding, leading to increased dietary fructoselysine exposure, seems to result in an increased fructoselysine degradation activity in the gut microbiota of infants. This indicates that the infant gut microbiota adapts towards dietary fructoselysine exposure.

Religious fasting and its impacts on individual, public, and planetary health: Fasting as a "religious health asset" for a healthier, more equitable, and sustainable society

Religious fasting is practiced by people of all faiths, including Christianity, Islam, Buddhism, Jainism, as well as Hinduism, Judaism, and Taoism. Individual/clinical, public, global, and planetary health has traditionally been studied as separate entities. Nevertheless, religious fasting, in conjunction with other religious health assets, can provide several opportunities, ranging from the individual to the population, environmental, and planetary levels, by facilitating and supporting societal transformations and changes, such as the adoption of healthier, more equitable, and sustainable lifestyles, therein preserving the Earth's systems and addressing major interconnected, cascading, and compound challenges. In this review, we will summarize the most recent evidence on the effects of religious fasting, particularly Orthodox and Ramadan Islamic fasting, on human and public health. Further, we will explore the potential effects of religious fasting on tackling current environmental issues, with a special focus on nutrition/food restriction and planetary health. Finally, specific recommendations, particularly around dietary intake during the fasting rituals, will be provided to ensure a sustainable healthy planet.

Butyrate-producing colonic clostridia: picky glycan utilization specialists

Butyrate-producing human gut microbiota members are recognized for their strong association with a healthy immune-homeostasis and protection from inflammatory disorders and colorectal cancer. These effects are attributed to butyrate, the terminal electron sink of glycan fermentation by prevalent and abundant colonic Firmicutes from the Lachnospiraceae and Oscillospiraceae families. Remarkably, our insight into the glycan utilization mechanisms and preferences of butyrogenic Firmicutes remains very limited as compared with other gut symbionts, especially from the Bacteroides, Bifidobacterium, and Lactobacillus genera. Here, we summarize recent findings on the strategies that colonic butyrate producers have evolved to harvest energy from major dietary fibres, especially plant structural and storage glycans, such as resistant starch, xylans, and mannans. Besides dietary fibre, we also present the unexpected discovery of a conserved protein apparatus that confers the growth of butyrate producers on human milk oligosaccharides (HMOs), which are unique to mother’s milk. The dual dietary fibre/HMO utilization machinery attests the adaptation of this group to both the infant and adult guts. These finding are discussed in relation to the early colonization of butyrogenic bacteria and the maturation of the microbiota during the transition from mother’s milk to solid food. To date, the described butyrogenic Firmicutes are glycan utilization specialists that target only a few glycans in a highly competitive manner relying on co-regulated glycan utilization loci. We describe the common pillars of this machinery, highlighting butyrate producers as a source for discovery of biochemically and structurally novel carbohydrate active enzymes.

Effect of feeding raw potato starch on the composition dynamics of the piglet intestinal microbiome

OBJECTIVE

Raw potato starch (RPS) is resistant to digestion, escapes absorption, and is metabolized by intestinal microflora in the large intestine and acts as their energy source. In this study, we compared the effect of different concentrations of RPS on the intestinal bacterial community of weaned piglets.

METHODS

Male weaned piglets (25-days-old, 7.03±0.49 kg) were either fed a corn/soybean-based control diet (CON, n = 6) or two treatment diets supplemented with 5% RPS (RPS5, n = 4) or 10% RPS (RPS10, n = 4) for 20 days and their fecal samples were collected. The day 0 and 20 samples were analyzed using a 16S rRNA gene sequencing technology, followed by total genomic DNA extraction, library construction, and high-throughput sequencing. After statistical analysis, five phyla and 45 genera accounting for over 0.5% of the reads in any of the three groups were further analyzed. Furthermore, short-chain fatty acids (SCFAs) in the day 20 fecal samples were analyzed using gas chromatography.

RESULTS

Significant changes were not observed in the bacterial composition at the phylum level even after 20 d post feeding (dpf); however, the abundance of Intestinimonas and Barnesiella decreased in both RPS treatment groups compared to the CON group. Consumption of 5% RPS increased the abundance of Roseburia (p<0.05) and decreased the abundance of Clostridium (p<0.01) and Mediterraneibacter (p< 0.05). In contrast, consumption of 10% RPS increased the abundance of Olsenella (p<0.05) and decreased the abundance of Campylobacter (p<0.05), Kineothrix (p<0.05), Paraprevotella (p<0.05), and Vallitalea (p<0.05). Additionally, acetate (p<0.01), butyrate (p<0.05), valerate (p = 0.01), and total SCFAs (p = 0.01) were upregulated in the RPS5 treatment group.

CONCLUSION

Feeding 5% RPS altered bacterial community composition and promoted gut health in weaned piglets. Thus, resistant starch as a feed additive may prevent diarrhea in piglets during weaning.

Nutrient and Maillard reaction product concentrations of commercially available pet foods and treats

Thermal processing is used to produce most commercial pet foods and treats to improve safety, shelf life, nutritional characteristics, texture, and nutrient digestibility. However, heat treatments can degrade protein quality by damaging essential amino acids, as well as contribute to the Maillard reaction. The Maillard reaction forms melanoidins that favorably improve food qualities (e.g., color, flavor, aroma), but also form Maillard reaction products (MRP) and advanced glycation end-products that may negatively affect health. Because commercial pet diets are frequently fed to domestic cats and dogs throughout their lifetimes, it is critical to quantify MRP concentrations and understand the variables that influence their formation so future diets may be formulated with that in mind. Because few research studies on MRP in pet diets have been conducted, the goals of this study were to measure the MRP in commercial pet foods and treats, estimate pet MRP intake, and correlate MRP with dietary macronutrient concentrations. Fifty-three dry and wet dog foods, dog treats, and cat foods were analyzed for dry matter, organic matter, crude protein, acid-hydrolyzed fat, total dietary fiber, and gross energy using standard techniques. MRP were analyzed using high-performance liquid chromatography and gas chromatography-mass spectrometry. Data were analyzed using the Mixed Models procedure of SAS 9.4. Dry foods had lower reactive lysine concentrations and reactive lysine: total lysine ratios (indicator of damage) than wet foods. Wet foods had more fructoselysine (FRUC) than dry foods; however, dry dog treats contained more FRUC than wet dog treats. The greatest 5-hydroxymethyl-2-furfural (HMF) concentrations were measured in dry and wet dog foods, whereas the lowest HMF concentrations were measured in dry and wet cat foods. Based on dietary concentrations and estimated food intakes, dogs and cats fed wet foods are more likely to consume higher carboxymethyllysine and FRUC concentrations than those fed dry foods. However, dogs fed wet foods are more likely to consume higher HMF concentrations than those fed dry foods. In cats, those fed dry foods would consume higher HMF concentrations than those fed wet foods. We demonstrated that pet foods and treats contain highly variable MRP concentrations and depend on diet/treat type. In general, higher MRP concentrations were measured in wet pet foods and dry treats. While these findings are valuable, in vivo testing is needed to determine if and how MRP consumption affect pet health.

Depression and fatigue in active IBD from a microbiome perspective-a Bayesian approach to faecal metagenomics

BACKGROUND

Extraintestinal symptoms are common in inflammatory bowel diseases (IBD) and include depression and fatigue. These are highly prevalent especially in active disease, potentially due to inflammation-mediated changes in the microbiota-gut-brain axis. The aim of this study was to investigate the associations between structural and functional microbiota characteristics and severity of fatigue and depressive symptoms in patients with active IBD.

METHODS

We included clinical data of 62 prospectively enrolled patients with IBD in an active disease state. Patients supplied stool samples and completed the questionnaires regarding depression and fatigue symptoms. Based on taxonomic and functional metagenomic profiles of faecal gut microbiota, we used Bayesian statistics to investigate the associative networks and triangle motifs between bacterial genera, functional modules and symptom severity of self-reported fatigue and depression.

RESULTS

Associations with moderate to strong evidence were found for 3 genera (Odoribacter, Anaerotruncus and Alistipes) and 3 functional modules (pectin, glycosaminoglycan and central carbohydrate metabolism) with regard to depression and for 4 genera (Intestinimonas, Anaerotruncus, Eubacterium and Clostridiales g.i.s) and 2 functional modules implicating amino acid and central carbohydrate metabolism with regard to fatigue.

CONCLUSIONS

This study provides the first evidence of association triplets between microbiota composition, function and extraintestinal symptoms in active IBD. Depression and fatigue were associated with lower abundances of short-chain fatty acid producers and distinct pathways implicating glycan, carbohydrate and amino acid metabolism. Our results suggest that microbiota-directed therapeutic approaches may reduce fatigue and depression in IBD and should be investigated in future research.

The effects of Clostridium butyricum on Ira rabbit growth performance, cecal microbiota and plasma metabolome

Clostridium butyricum (C. butyricum) can provide many benefits for animals’ growth performance and gut health. In this study, we investigated the effects of C. butyricum on the growth performance, cecal microbiota, and plasma metabolome in Ira rabbits. A total of 216 Ira rabbits at 32 days of age were randomly assigned to four treatments supplemented with basal diets containing 0 (CG), 200 (LC), 400 (MC), and 600 mg/kg (HC) C. butyricum for 35 days, respectively. In comparison with the CG group, C. butyricum supplementation significantly improved the average daily gain (ADG) and feed conversion rate (FCR) at 53 and 67 days of age (P < 0.05) and digestibilities of crude protein (CP) and crude fiber (CF) at 67 days of age (P < 0.05). The cellulase activity in the HC group was higher respectively by 50.14 and 90.13% at 53 and 67 days of age, than those in the CG groups (P < 0.05). Moreover, at 67 days of age, the diet supplemented with C. butyricum significantly increased the relative abundance of Verrucomicrobia at the phylum level (P < 0.05). Meanwhile, the concentrations of different metabolites, such as amino acids and purine, were significantly altered by C. butyricum (P < 0.05). In addition, 10 different genera were highly correlated with 52 different metabolites at 53-day-old and 6 different genera were highly correlated with 18 different metabolites at 67-day-old Ira rabbits. These findings indicated that the C. butyricum supplementation could significantly improve the growth performance by modifying the cecal microbiota structure and plasma metabolome of weaned Ira rabbits.

Inter- and Intraindividual Differences in the Capacity of the Human Intestinal Microbiome in Fecal Slurries to Metabolize Fructoselysine and Carboxymethyllysine

The advanced glycation endproduct carboxymethyllysine and its precursor fructoselysine are present in heated, processed food products and are considered potentially hazardous for human health. Upon dietary exposure, they can be degraded by human colonic gut microbiota, reducing internal exposure. Pronounced interindividual and intraindividual differences in these metabolic degradations were found in anaerobic incubations with human fecal slurries in vitro. The average capacity to degrade fructoselysine was 27.7-fold higher than that for carboxymethyllysine, and degradation capacities for these two compounds were not correlated (R² = 0.08). Analysis of the bacterial composition revealed that interindividual differences outweighed intraindividual differences, and multiple genera were correlated with the individuals' carboxymethyllysine and fructoselysine degradation capacities (e.g., Akkermansia, Alistipes).

Comprehensive analysis of microbiome, metabolome and transcriptome revealed the mechanisms of Moringa oleifera polysaccharide on preventing ulcerative colitis

This study aimed to investigate the protective effect of Moringa oleifera polysaccharide (MOP) on ulcerative colitis (UC) and explore its mechanism through the combined analysis of microbiome, metabolome and transcriptome. A UC model in mice was established using dextran sulphate sodium. After a 21-day experiment, results showed that MOP could inhibit the weight loss and disease activity index in UC mice. The intervention of MOP decreased the expression of inflammatory cytokines and promoted the secretion of tight junctions. MOP could promote the growth of probiotics such as Lachnospiraceae_NK4A136, Intestinimonas and Bifidobacterium in UC mice. The results of metabolomic and transcriptomic analysis indicated that MOP could regulated the metabolism of polyunsaturated fatty acid and PPAR, TLR and TNF signalling pathways might play important roles in the process. Altogether, MOP could be used as a functional food to prevent UC.

Fecal microbiota in patients with a stoma decreases anaerobic bacteria and alters taxonomic and functional diversities

Colorectal cancer (CRC) is one of the most common malignant diseases. Generally, stoma construction is performed following surgery for the resection of the primary tumor in patients with CRC. The association of CRC with the gut microbiota has been widely reported, and the gut microbiota is known to play an important role in the carcinogenesis, progression, and treatment of CRC. In this study, we compared the microbiota of patients with CRC between with and without a stoma using fecal metagenomic sequencing data from SCRUM-Japan MONSTAR-SCREEN, a joint industry-academia cancer research project in Japan. We found that the composition of anaerobes was reduced in patients with a stoma. In particular, the abundance of Alistipes, Akkermansia, Intestinimonas, and methane-producing archaea decreased. We also compared gene function (e.g., KEGG Orthology and KEGG pathway) and found that gene function for methane and short-chain fatty acids (SCFAs) production was underrepresented in patients with a stoma. Furthermore, a stoma decreased Shannon diversity based on taxonomic composition but increased that of the KEGG pathway. These results suggest that the feces of patients with a stoma have a reduced abundance of favorable microbes for cancer immunotherapy. In conclusion, we showed that a stoma alters the taxonomic and functional profiles in feces and may be a confounding factor in fecal microbiota analysis.

Supplementing the early diet of broilers with soy protein concentrate can improve intestinal development and enhance short-chain fatty acid-producing microbes and short-chain fatty acids, especially butyric acid

Background

Research on nutrition in early-life commonly focuses on the maturation of the intestine because the intestinal system is crucial for ensuring continued growth. To explore the importance of early nutrition regulation in animals, soy protein concentrate (SPC) was added to the early diet of broilers to investigate its effects on amino acid digestibility, intestinal development, especially intestinal microorganisms, and broiler metabolites. A total of 192 one-day-old Arbor Acres (AA) male broilers were randomly assigned to two experimental treatments with 8 replicates of 12 birds. The control group was fed a basal diet (control), and the treatment group was fed a basal diet supplemented with 12% SPC (SPC12) during the first 10 d (starter phase). From d 11 to 21 (grower phase) and d 22 to 42 (finisher phase), a basal diet was fed to both treatment groups.

Results

SPC reduced the pH value and acid-binding capacity of the starter diet (P < 0.05, d 10); SPC in the early diet enhanced the gizzard weight (P < 0.05, d 10 and d 42) and the ileum weight (P < 0.05, d 10) and decreased the weight and length of the jejunum (P < 0.05, d 10) and the relative length of the duodenum and jejunum (P < 0.05, d 10). At the same time, SPC enhanced villus height (P < 0.05, d 10) and muscle thickness in the jejunum and ileum (P < 0.05, d 10) and increased the number of goblet cells in the duodenum (P < 0.05, d 10). Meanwhile, SPC increased the Chao1 index and the ACE index (P < 0.05, d 10) and altered the composition of caecal microflora at d 10. SPC also increased the relative abundance of Alistipes, Anaerotruncus, Erysipelatoclostridium, Intestinimonas and Flavonifractor bacteria (P < 0.05, d 10). At the same time, the concentrations of caecal butyric acid and total short-chain fatty acids (SCFAs) were also increased in the SPC12 group (P < 0.05, d 10).

Conclusions

In summary, the results showed that supplementing the starter diet of broilers with SPC has a significant effect on the early development of the intestine and the microflora.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00749-5.

Microbial Tryptophan Metabolism Tunes Host Immunity, Metabolism, and Extraintestinal Disorders

The trillions of commensal microorganisms comprising the gut microbiota have received growing attention owing to their impact on host physiology. Recent advances in our understandings of the host–microbiota crosstalk support a pivotal role of microbiota-derived metabolites in various physiological processes, as they serve as messengers in the complex dialogue between commensals and host immune and endocrine cells. In this review, we highlight the importance of tryptophan-derived metabolites in host physiology, and summarize the recent findings on the role of tryptophan catabolites in preserving intestinal homeostasis and fine-tuning immune and metabolic responses. Furthermore, we discuss the latest evidence on the effects of microbial tryptophan catabolites, describe their mechanisms of action, and discuss how perturbations of microbial tryptophan metabolism may affect the course of intestinal and extraintestinal disorders, including inflammatory bowel diseases, metabolic disorders, chronic kidney diseases, and cardiovascular diseases.