Salmonella enterica serovar Typhimurium is a food-borne pathogen and a major cause of gastroenteritis in humans. The intestinal microbiota provides colonization resistance to enteric pathogens such as S. Typhimurium. Akkermansia muciniphila is an anaerobic bacterium commonly found in the intestinal tract of humans and other mammals and specializes in the degradation of mucin. To study the role of A. muciniphila in affecting the outcome of S. Typhimurium colonization and pathology, we used gnotobiotic mice colonized with a defined simplified human (SIHUMI) or mouse (OMM11) intestinal microbiota and infected them with the attenuated S. Typhimurium ΔaroA strain. By comparing SIHUMI and OMM11 mice to mice additionally colonized with A. muciniphila, we demonstrate that the presence of A. muciniphila leads to a decrease in intestinal Salmonella colonization. In addition, Salmonella-induced colitis is significantly reduced in the presence of A. muciniphila including improved histopathological changes as well as decreased levels of inflammatory cytokines. Furthermore, we demonstrate that viable A. muciniphila inhibit adhesion of Salmonella to the intestinal epithelium in vivo as well as to differentiated, polarized HT29-MTX-E12 epithelial cells. These data indicate that A. muciniphila plays an important role in mediating protection from S. Typhimurium colitis by inhibiting adhesion of Salmonella to the intestinal epithelium.

Gastrointestinal dysbiosis is common among persons with type 1 diabetes (T1D), but its potential impact on diabetic nephropathy (DN) remains obscure. We examined whether faecal biomarkers, previously associated with low-grade gastrointestinal inflammation, differ between healthy controls and T1D subjects with and without DN. Faecal samples were analyzed for levels of calprotectin, intestinal alkaline phosphatase (IAP), short-chain fatty acids (SCFA) and immunoglobulins in subjects with T1D (n = 159) and healthy controls (NDC; n = 50). The subjects with T1D were stratified based on albuminuria: normoalbuminuria (< 30 mg/g; n = 49), microalbuminuria (30–299 mg/g; n = 50) and macroalbuminuria (≥ 300 mg/g; n = 60). aecal calprotectin, IAP and immunoglobulin levels did not differ between the T1D albuminuria groups. However, when subjects were stratified based on faecal calprotectin cut-off level (50 µg/g), macroalbuminuric T1D subjects exceeded the threshold more frequently than NDC ( p = 0.02). Concentrations of faecal propionate and butyrate were lower in T1D subjects compared with NDC ( p = 0.04 and p = 0.03, respectively). Among T1D subjects, levels of branched SCFA (BCFA) correlated positively with current albuminuria level (isobutyrate, p = 0.03; isovalerate, p = 0.005). In our study cohort, fatty acid metabolism seemed to be altered among T1D subjects and those with albuminuria compared to NDC. This may reflect gastrointestinal imbalances associated with T1D and renal complications.

The interplay between diet, intestinal microbiota and host is a major factor impacting health. A diet rich in unsaturated fatty acids has been reported to stimulate the growth of Bilophila wadsworthia by increasing the proportion of the sulfonated bile acid taurocholate (TC). The taurine-induced overgrowth of B. wadsworthia promoted the development of colitis in interleukin-10-deficient (IL-10-/-) mice. This study aimed to investigate whether intake of the sulfonates sulfoquinovosyl diacylglycerols (SQDG) with a dietary supplement or their degradation product sulfoquinovose (SQ), stimulate the growth of B. wadsworthia in a similar manner and, thereby, cause intestinal inflammation. Conventional IL-10-/- mice were fed a diet supplemented with the SQDG-rich cyanobacterium Arthrospira platensis (Spirulina). SQ or TC were orally applied to conventional IL-10-/- mice and gnotobiotic IL-10-/- mice harboring a simplified human intestinal microbiota with or without B. wadsworthia. Analyses of inflammatory parameters revealed that none of the sulfonates induced severe colitis, but both, Spirulina and TC, induced expression of pro-inflammatory cytokines in cecal mucosa. Cell numbers of B. wadsworthia decreased almost two orders of magnitude by Spirulina feeding but slightly increased in gnotobiotic SQ and conventional TC mice. Changes in microbiota composition were observed in feces as a result of Spirulina or TC feeding in conventional mice. In conclusion, the dietary sulfonates SQDG and their metabolite SQ did not elicit bacteria-induced intestinal inflammation in IL-10-/- mice and, thus, do not promote colitis.

Background: Roux-en-Y gastric bypass (RYGB) surgery is an effective treatment for obesity, which improves cardiovascular health and reduces the risk of premature mortality. However, some reports have suggested that RYGB may predispose patients to adverse health outcomes, such as inflammatory bowel disease (IBD) and colorectal cancer. Objectives: The present prospective study aimed to evaluate the impact of RYGB surgery on cardiovascular risk factors and gastrointestinal inflammation in individuals with and without type 2 diabetes (T2D). Setting: University hospital setting in Finland. Methods: Blood and fecal samples were collected at baseline and 6 months after surgery from 30 individuals, of which 16 had T2D and 14 were nondiabetics. There were also single study visits for 6 healthy reference patients. Changes in cardiovascular risk factors, serum cholesterol, and triglycerides were investigated before and after surgery. Fecal samples were analyzed for calprotectin, anti-Saccharomyces cerevisiae immunoglobulin A antibodies (ASCA), active lipopolysaccharide (LPS) concentration, short-chain fatty acids (SCFAs), intestinal alkaline phosphatase activity, and methylglyoxal-hydro-imidazolone (MG-H1) protein adducts formation. Results: After RYGB, weight decreased on average 221.6% (-27.2 +/- 7.8 kg), excess weight loss averaged 51%, and there were improvements in cardiovascular risk factors. Fecal calprotectin levels (P < .001), active LPS concentration (P < .002), ASCA (P < .02), and MG-H1 (P < .02) values increased significantly, whereas fecal SCFAs, especially acetate (P < .002) and butyrate (P < .03) levels, were significantly lowered. Conclusion: The intestinal homeostasis is altered after RYGB, with several fecal markers suggesting increased inflammation; however, clinical significance of the detected changes is currently uncertain. As chronic inflammation may predispose patients to adverse health effects, our findings may have relevance for the suggested association between RYGB and increased risks of incident IBD and colorectal cancer. (C) 2020 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.

Introduction: Many retrospective studies have linked asthma, the leading chronic disease in children worldwide, with antibiotic use during pregnancy or in early life. However, neither the causal relationship nor the possible mechanisms have been clearly defined. Additionally, existing mouse models treat both mothers and offspring with antibiotic, making it difficult to investigate the maternal/prenatal contribution to offspring asthma susceptibility. To deal with these issues, we designed a model where treatment of mothers with antibiotic only during pregnancy results in increased offspring asthma severity.

It is assumed that diet influences the composition of gut microbiota, which in turn may affect human health status. This systematic review aimed to summarize associations of a vegan or vegetarian diet with the composition of microbiota. A literature search was conducted in PubMed and Embase for eligible human studies with vegan or vegetarian diets as an exposure and microbiota composition as an outcome in healthy adults. Furthermore, data from our cross-sectional study with vegan participants were included. Out of sixteen included studies, six investigated the association between gut microbiota composition in both vegans and in vegetarians, six in vegans and four studies in vegetarians compared to omnivores, respectively. Among 5 different phyla, 28 families, 96 genera and 177 species, Bacteroides, Bifidobacterium and Prevotella were the most reported genera, followed by the species Prevotella copri, Faecalibacterium prausnitzii and Escherichia coli in all diets. No consistent association between a vegan diet or vegetarian diet and microbiota composition compared to omnivores could be identified. Moreover, some studies revealed contradictory results. This result could be due to high microbial individuality, and/or differences in the applied approaches. Standardized methods with high taxonomical and functional resolutions are needed to clarify this issue.

Background: The use of antibiotics during pregnancy is associated with increased allergic asthma risk in the offspring, and given that approximately 25% of pregnant women are prescribed antibiotics, it is important to understand the mechanisms contributing to this phenomenon. Currently, there are no studies that directly test this association experimentally. Our objective was to develop a mouse model in which antibiotic treatment during pregnancy results in increased offspring asthma susceptibility. Methods: Pregnant mice were treated daily from gestation day 8-17 with an oral solution of the antibiotic vancomycin, and three concentrations were tested. At weaning, offspring were subjected to an adjuvant-free experimental asthma protocol using ovalbumin as an allergen. The composition of the gut microbiome was determined in mothers and offspring with samples collected from five different time points; shortchain fatty acids were also analyzed in allergic offspring. Results: We found that maternal antibiotic treatment during pregnancy was associated with increased offspring asthma severity in a dose-dependent manner. Furthermore, maternal vancomycin treatment during pregnancy caused marked changes in the gut microbiome composition in both mothers and pups at several different time points. The increased asthma severity and intestinal microbiome changes in pups were also associated with significantly decreased cecal short-chain fatty acid concentrations. Conclusion: Consistent with the "Developmental Origins Hypothesis," our results confirm that exposure to antibiotics during pregnancy shapes the neonatal intestinal environment and increases offspring allergic lung inflammation.

(1) Introduction: Sulfonates, which can be diet- or host-derived, are a class of compounds detected in the gut, are involved in host–microbiome interactions and have several health effects. Our aim was to develop a method to quantify five of the sulfonates in the intestine and apply it in a simplified human microbiome model. These were taurine, its metabolic precursor cysteate and one of its degradation products isethionate, as well as sulfoquinovose and one of its most relevant degradation products 2,3-dihydroxy-1-propanesulfonate. (2) Methods: An extraction and sample preparation method was developed, without the need for derivatization. To detect and quantify the extracted sulfonates, a multiplexed LC-MS/MS-MRM method was established. (3) Results: The accuracy and precision of the method were within GLP-accepted parameters. To apply this method in a pilot study, we spiked either taurine or sulfoquinovose into an in vitro simplified human microbiota model with and without Bilophila wadsworthia, a known sulfonate utilizer. The results revealed that only the culture with B. wadsworthia was able to degrade taurine, with isethionate as an intermediate. After spiking the communities with sulfoquinovose, the results revealed that the simplified human microbiome model was able to degrade sulfoquinovose to 2,3-dihydroxypropane-1-sulfonate, which was probably catalyzed by Escherichia coli. In the community with B. wadsworthia, the 2,3-dihydroxypropane-1-sulfonate produced was further degraded by B. wadsworthia to sulfide. (4) Conclusions: We successfully developed a method for sulfonate quantification and applied it in a first pilot study.

The rising prevalence of type 1 diabetes (T1D) over the past decades has been linked to lifestyle changes, but the underlying mechanisms are largely unknown. Recent findings point to gut-associated mechanisms in the control of T1D pathogenesis. In nonobese diabetic (NOD) mice, a model of T1D, diabetes development accelerates after deletion of the Toll-like receptor 4 (TLR4). We hypothesized that altered intestinal functions contribute to metabolic alterations, which favor accelerated diabetes development in TLR4-deficient (TLR4 −/− ) NOD mice. In 70–90-day-old normoglycemic (prediabetic) female NOD TLR4 +/+ and NOD TLR4 −/− mice, gut morphology and microbiome composition were analyzed. Parameters of lipid metabolism, glucose homeostasis, and mitochondrial respiratory activity were measured in vivo and ex vivo . Compared with NOD TLR4 +/+ mice, NOD TLR4 −/− animals showed lower muscle mass of the small intestine, higher abundance of Bacteroidetes, and lower Firmicutes in the large intestine, along with lower levels of circulating short-chain fatty acids (SCFA). These changes are associated with higher body weight, hyperlipidemia, and severe insulin and glucose intolerance, all occurring before the onset of diabetes. These mice also exhibited insulin resistance–related abnormalities of energy metabolism, such as lower total respiratory exchange rates and higher hepatic oxidative capacity. Distinct alterations of gut morphology and microbiota composition associated with reduction of circulating SCFA may contribute to metabolic disorders promoting the progression of insulin-deficient diabetes/T1D development.

Peripheral serotonin (5-hydroxytryptamine: 5-HT) synthesized in the intestine by enterochromaffin cells (ECs), plays an important role in the regulation of peristaltic of the gut, epithelial secretion and promotes the development and maintenance of the enteric neurons. Recent studies showed that the indigenous gut microbiota modulates 5-HT signalling and that ECs use sensory receptors to detect dietary and microbiota-derived signals from the lumen to subsequently transduce the information to the nervous system. We hypothesized that Clostridium ramosum by increasing gut 5-HT availability consequently contributes to high-fat diet-induced obesity. Using germ-free mice and mice monoassociated with C . ramosum , intestinal cell lines and mouse organoids, we demonstrated that bacterial cell components stimulate host 5-HT secretion and program the differentiation of colonic intestinal stem progenitors toward the secretory 5-HT-producing lineage. An elevated 5-HT level regulates the expression of major proteins involved in intestinal fatty acid absorption in vitro , suggesting that the presence of C . ramosum in the gut promotes 5-HT secretion and thereby could facilitates intestinal lipid absorption and the development of obesity.

BACKGROUND AND AIMS Contact with distinct microbiota early in life has been shown to educate the mucosal immune system, hence providing protection against immune-mediated diseases. However, the impact of early versus late colonization with regard to the development of the intestinal macrophage compartment has not been studied so far. METHODS Germ-free mice were colonized with specific-pathogen-free [SPF] microbiota at the age of 5 weeks. The ileal and colonic macrophage compartment were analysed by immunohistochemistry, flow cytometry, and RNA sequencing 1 and 5 weeks after colonization and in age-matched SPF mice, which had had contact with microbiota since birth. To evaluate the functional differences, dextran sulfate sodium [DSS]-induced colitis was induced, and barrier function analyses were undertaken. RESULTS Germ-free mice were characterized by an atrophied intestinal wall and a profoundly reduced number of ileal macrophages. Strikingly, morphological restoration of the intestine occurred within the first week after colonization. In contrast, ileal macrophages required 5 weeks for complete restoration, whereas colonic macrophages were numerically unaffected. However, following DSS exposure, the presence of microbiota was a prerequisite for colonic macrophage infiltration. One week after colonization, mild colonic inflammation was observed, paralleled by a reduced inflammatory response after DSS treatment, in comparison with SPF mice. This attenuated inflammation was paralleled by a lack of TNFα production of LPS-stimulated colonic macrophages from SPF and colonized mice, suggesting desensitization of colonized mice by the colonization itself. CONCLUSIONS This study provides the first data indicating that after colonization of adult mice, the numeric, phenotypic, and functional restoration of the macrophage compartment requires the presence of intestinal microbiota and is time dependent.

The human intestinal anaerobe Eubacterium ramulus is known for its ability to degrade various dietary flavonoids. In the present study, we demonstrate the cleavage of the heterocyclic C-ring of flavanones and flavanonols by an oxygen-sensitive NADH-dependent reductase, previously described as enoate reductase, from E. ramulus This flavanone- and flavanonol-cleaving reductase (Fcr) was purified following its heterologous expression in Escherichia coli and further characterized. Fcr cleaved the flavanones naringenin, eriodictyol, liquiritigenin, and homoeriodictyol. Moreover, the flavanonols taxifolin and dihydrokaempferol served as substrates. The catalyzed reactions were stereospecific for the (2R)-enantiomers of the flavanone substrates and for the (2S,3S)-configured flavanonols. The enantioenrichment of the nonconverted stereoisomers allowed for the determination of hitherto unknown flavanone racemization rates. Fcr formed the corresponding dihydrochalcones and hydroxydihydrochalcones in the course of an unusual reductive cleavage of cyclic ether bonds. Fcr did not convert members of other flavonoid subclasses, including flavones, flavonols, and chalcones, the latter indicating that the reaction does not involve a chalcone intermediate. This view is strongly supported by the observed enantiospecificity of Fcr. Cinnamic acids, which are typical substrates of bacterial enoate reductases, were also not reduced by Fcr. Based on the presence of binding motifs for dinucleotide cofactors and a 4Fe-4S cluster in the amino acid sequence of Fcr, a cofactor-mediated hydride transfer from NADH onto C-2 of the respective substrate is proposed.IMPORTANCE Gut bacteria play a crucial role in the metabolism of dietary flavonoids, thereby contributing to their activation or inactivation after ingestion by the human host. Thus, bacterial activities in the intestine may influence the beneficial health effects of these polyphenolic plant compounds. While an increasing number of flavonoid-converting gut bacterial species have been identified, knowledge of the responsible enzymes is still limited. Here, we characterized Fcr as a key enzyme involved in the conversion of flavonoids of several subclasses by Eubacterium ramulus, a prevalent human gut bacterium. Sequence similarity of this enzyme to hypothetical proteins from other flavonoid-degrading intestinal bacteria in databases suggests a more widespread occurrence of this enzyme. Functional characterization of gene products of human intestinal microbiota enables the assignment of metagenomic sequences to specific bacteria and, more importantly, to certain activities, which is a prerequisite for targeted modulation of gut microbial functionality.

An anaerobic Gram-stain-positive, non-spore-forming and non-motile bacterium isolated from the human gut, designated CG19-1T, capable of cleaving aromatic C-glucosides was characterized using a polyphasic taxonomic approach. Major fermentation products of this asaccharolytic organism were acetate and butyrate when grown on a complex medium. Growth of strain CG19-1T was stimulated by glucose or pyruvate. Growth inhibition was observed in the presence of several phenolic acids including ferulic acid, which nevertheless was reduced to dihydroferulic acid. Strain CG19-1T contained peptidoglycan type A4β l-Orn-d-Asp. The major cellular fatty acids were C16 : 0 and C18 : 1ω9c. The genomic DNA G+C content was 47.1 mol%. Based on its 16S rRNA gene sequence, strain CG19-1T is a member of the Lachnospiraceae. However, sequence identity to other Lachnospiraceae species with validly published names is approximately 93.0 % with Frisingicoccus caecimuris being the most closely related species according to phylogenetic analysis. Based on these findings, it is proposed to create a novel genus, Catenibacillus, and a novel species, Catenibacillus scindens, with the type strain CG19-1T (=DSM 106146T=CCUG 71490T).

Akkermansia muciniphila is a common member of the intestinal microbiota of healthy human individuals. Its abundance is negatively associated with inflammatory bowel disease and metabolic disorders and the oral administration of A. muciniphila improves the symptoms of metabolic disease in mice. Therefore, A. muciniphila is a promising candidate for the treatment of type-2 diabetes and obesity. However, some studies using animal models of intestinal inflammation reported that A. muciniphila may exacerbate gut inflammation. Because of these contradictory reports the present study aimed to clarify the role of A. muciniphila in the development of intestinal inflammation and the conditions promoting it. For this purpose, the short-term colitogenic potential of A. muciniphila strain ATCC BAA-835 was investigated in colitis-prone, gnotobiotic IL-10-deficient (Il10-/-) mice. Il10-/- mice mono-associated with A. muciniphila showed no signs of intestinal inflammation based on body-weight change, histopathological scoring and inflammatory markers. Additional association of the mice with the colitogenic Escherichia coli strain NC101 led to cecal but not colonic inflammation. However, the severity of the inflammation did not exceed that observed in mice mono-associated with E. coli NC101. Il10-/- mice colonized with a simplified human intestinal microbiota showed increased histopathology, but no increase in inflammatory markers. Furthermore, co-colonization with A. muciniphila did not modify histopathology. The turnover of intestinal mucus was similar in all groups despite the mucus-degrading property of A. muciniphila. Overall, the data do not support a short-term pro-inflammatory effect of A. muciniphila strain ATCC BAA-835 in the Il10-/- mouse model for inflammatory bowel disease.

Human neutrophil elastase is an important regulator of the immune response and plays a role in host defense mechanisms and further physiological processes. The uncontrolled activity of this serine protease may cause severe tissue alterations and impair inflammatory states. The design of an activity-based probe for human neutrophil elastase reported herein relies on a sulfonyloxyphthalimide moiety as a new type of warhead that is linker-connected to a coumarin fluorophore. The inhibitory potency of the activity-based probe was assessed against several serine and cysteine proteases, and the selectivity for human neutrophil elastase (Ki = 6.85 nM) was determined. The adequate fluorescent tag of the probe allowed for the in-gel fluorescence detection of human neutrophil elastase in the low nanomolar range. The coumarin moiety and the anthranilic acid function of the probe, produced in the course of a Lossen rearrangement, were part of two different Förster resonance energy transfers.

In a recent article in Cell Reports, Dalby and colleagues convincingly demonstrate that choosing an inadequate control diet in animal experiments that investigate the interaction of nutrition, gut microbiota, and obesity development may lead to the wrong conclusions. The authors systematically compared the effects of refined high- and low-fat diets (rHFD and rLFD) with those of a standard chow diet on mouse physiology, microbiota composition, cecal fermentation, and intestinal morphology. The results obtained in this study question the conclusions drawn from animal studies that compared the effects of HFDs with those of chow diets.

This study aimed to explore the dominant fecal microbiota and fecal short chain fatty acid metabolites in Egyptian adults. The impact of a three week dietary intervention with fermented sour sobya (SS) providing daily 1.56 ± 0.22 and 1.79 ± 0.14 billion colonies forming units of Lactobacilli and yeasts, respectively on the fecal microbiota and metabolites in healthy adults were also investigated. The abundances of 12 bacterial taxa were characterized before and after three-week daily intake of SS by quantitative real time PCR. Fecal short chain fatty acids were analyzed in parallel with gas chromatography. The intervention with SS led to more than 46-fold average increase in genome numbers of Lactobacillus rhamnosus, potential probiotic present in SS. Fecal Enterobacteriaceae and its genus Escherichia, which are often associated with pathogenic traits and inflammation, were reduced significantly following the three week intake of SS. The intake of SS was also associated with significant increase in fecal short chain fatty acids including butyrate. These data provide evidence of unique beneficial effects for the use of microbiome-based therapies such as fermented sour sobya in clinical and molecular nutrition and medicine.

Human leukocyte elastase plays a crucial role in a variety of inflammatory disorders and represents an important subject of biomedical studies. The chemotype of peptidic phosphonates was employed for the design of a new activity-based probe for human leukocyte elastase. Its structure combines the phosphonate warhead with an adequate peptide portion and a BODIPY fluorophore with a clickable ethinylphenyl moiety at meso position. The probe 6 was assembled by copper-catalyzed alkyne-azide 1,3-dipolar cycloaddition. It was characterized as an active site-directed elastase inhibitor exhibiting a second-order rate constant of inactivation of 88400 M-1s-1. The suitability of 6 as a fluorescent probe for human leukocyte elastase was demonstrated by in-gel fluorescence analysis. Labeling experiments and inhibition data toward a panel of related proteases underlined the selectivity of the probe for the targeted leukocyte elastase.