Bowel microbiota moderate host physiological responses to dietary konjac in weanling rats

Plant Extracts in Obesity: A Role of Gut Microbiota

Obesity has become one of the most serious chronic diseases threatening human health. Its occurrence and development are closely associated with gut microbiota since the disorders of gut microbiota can promote endotoxin production and induce inflammatory response. Recently, numerous plant extracts have been proven to mitigate lipid dysmetabolism and obesity syndrome by regulating the abundance and composition of gut microbiota. In this review, we summarize the potential roles of different plant extracts including mulberry leaf extract, policosanol, cortex moutan, green tea, honokiol, and capsaicin in regulating obesity via gut microbiota. Based on the current findings, plant extracts may be promising agents for the prevention and treatment of obesity and its related metabolic diseases, and the mechanisms might be associated with gut microbiota.

Bacitracin Methylene Disalicylate Improves Intestinal Health by Modulating Its Development and Microbiota in Weaned Rabbits

Intestinal infections are a major cause of morbidity and mortality in humans and agricultural animals, especially newborns and weaned animals. Preventive treatments that help weaned animals maintain homeostasis and balance the hindgut microbial populations are desirable. The present study aimed to explore the impact of bacitracin methylene disalicylate (BMD) on the intestinal health by analyzing the intestinal environment, morphology, expression of peptidoglycan recognition proteins (PGRPs), and flora of weaned rabbits. A total of 300 New Zealand weaned rabbits were randomly divided into the following five treatment groups for a 35-day feed trial: control group (basal diet), bacitracin zinc (BZ) group (50 mg/kg BZ), BMDa group (100 mg/kg BMD), BMDb group (50 mg/kg BMD), and BMDc group (rabbits fed a basal diet supplemented with 25 mg/kg BMD). In each treatment group, 28 rabbits were slaughtered for experimental analysis. The results showed that the supplementation of BMD increased the environmental acidity of the cecum of the weaned rabbits and reduced the ammonia-nitrogen concentration, which was beneficial to the survival of useful bacteria in the intestine. The morphology analysis of the duodenum using hematoxylin and eosin staining revealed that the villus length, villus/crypt ratio, and intestinal wall thickness increased in the BMD group, thereby improving the structure of the duodenum and the absorption capacity of the small intestine. Moreover, real-time polymerase chain reaction test showed that PGRPs (especially PGLYRP-1 and PGLYRP-2) in the intestinal had an antagonistic effect with BMD in the process of inhibiting pathogenic bacteria, resulting in their decreased expression (P < 0.05). Furthermore, through 16S rRNA sequencing in the cecal content, the abundance of the predominant phyla in the BMDa and BZ groups was found to be the closest. The abundance of the genera Lachnospira, Erysipelotrichaceae (p-75-a5), Paraprevotellaceae (YRC22), Mogibacterium, Peptococcaceae (rc4-4), Anaerovibrio, Succinivibrio, and Sphaerochaeta increased in the BMDa and BZ groups (P < 0.05). The relative abundance of Alistipes, Sedimentibacter, and Dorea significantly increased only in the BMDa group (P < 0.05). Conclusively, BMD, as well as microbes, improved the intestinal environment and structure to maintain the intestinal health of weaned rabbits.

Spatial heterogeneity of bacterial colonization across different gut segments following inter-species microbiota transplantation

BACKGROUND

The microbiota presents a compartmentalized distribution across different gut segments. Hence, the exogenous microbiota from a particular gut segment might only invade its homologous gut location during microbiota transplantation. Feces as the excreted residue contain most of the large-intestinal microbes but lack small-intestinal microbes. We speculated that whole-intestinal microbiota transplantation (WIMT), comprising jejunal, ileal, cecal, and colonic microbiota, would be more effective for reshaping the entire intestinal microbiota than conventional fecal microbiota transplantation fecal microbiota transplantation (FMT).

RESULTS

We modeled the compartmentalized colonization of the gut microbiota via transplanting the microbiota from jejunum, ileum, cecum, and colon, respectively, into the germ-free mice. Transplanting jejunal or ileal microbiota induced more exogenous microbes' colonization in the small intestine (SI) of germ-free mice rather than the large intestine (LI), primarily containing Proteobacteria, Lactobacillaceae, and Cyanobacteria. Conversely, more saccharolytic anaerobes from exogenous cecal or colonic microbiota, such as Bacteroidetes, Prevotellaceae, Lachnospiraceae, and Ruminococcaceae, established in the LI of germ-free mice that received corresponding intestinal segmented microbiota transplantation. Consistent compartmentalized colonization patterns of microbial functions in the intestine of germ-free mice were also observed. Genes related to nucleotide metabolism, genetic information processing, and replication and repair were primarily enriched in small-intestinal communities, whereas genes associated with the metabolism of essential nutrients such as carbohydrates, amino acids, cofactors, and vitamins were mainly enriched in large-intestinal communities of germ-free mice. Subsequently, we compared the difference in reshaping the community structure of germ-free mice between FMT and WIMT. FMT mainly transferred LI-derived microorganisms and gene functions into the recipient intestine with sparse SI-derived microbes successfully transplanted. However, WIMT introduced more SI-derived microbes and associated microbial functions to the recipient intestine than FMT. Besides, WIMT also improved intestinal morphological development as well as reduced systematic inflammation responses of recipients compared with FMT.

CONCLUSIONS

Segmented exogenous microbiota transplantation proved the spatial heterogeneity of bacterial colonization along the gastrointestinal tract, i.e., the microbiota from one specific location selectively colonizes its homologous gut region. Given the lack of exogenous small-intestinal microbes during FMT, WIMT may be a promising alternative for conventional FMT to reconstitute the microbiota across the entire intestinal tract. Video Abstract.

Konjaku flour reduces obesity in mice by modulating the composition of the gut microbiota

BACKGROUND

Changes in the intestinal flora composition is referred to as dysbiosis, which is related to obesity development, thus supporting the potential roles of nutrients acting on intestinal flora to exert salutary effects on energetic metabolism of host. Dietary fiber has been known to affect the composition of intestinal flora. The aim of the present study was to investigate the functional effects of konjac flour (KF) on obesity control in respect to improving inflammation, metabolism, and intestinal barrier function, and the possible association of the effects with intestinal flora composition changes.

METHODS

Mice (n = 30) were randomly divided into control group (n = 10), high-fat-diet (HFD) group (n = 10), and KF intervention group (n = 10), followed by feeding for 12 weeks and with adding a KF daily supplementation for the treatment group. Body weight, fat accumulation, inflammation, and energetic metabolism markers in multiple tissues and the gut microbiota of the mice were examined at the end of the experiment.

RESULTS

The KF supplementation significantly reduced the gains in weight, fat mass, as well as adipocyte size of HFD mice and lowered the serum TC, leptin (LEP), thiobarbituric acid-reacting substance (TBARS), IL-6, and lipopolysaccharide (LPS) levels in HFD mice. KF also upregulated the expression of intestinal mucosa protein gene Intection and tight junction ZO-1 in HFD mice, as well as upregulate the expression of energy metabolism genes PPARα and CPT-1 as well as the fat metabolism gene HLS in livers and fat tissues, and downregulate that of fat synthesis gene PPARγ (p < 0.05). The KF treatment increases the α-diversity and change the β-diversity of the intestinal microflora in HFD mice and boosted the abundances of some obesity-related beneficial microorganisms (such as Megasphaera elsdenii) in the intestinal microflora of HFD mice, while reduced those of harmful microorganisms (such as Alistipes, Alloprevotella, Bacteroides acidifaciens, and Parabacteroides goldsteinii). The abundance of Alistipes was positively correlated with weight, fat mass, serum TC, TG, LEP, IL-6, and LPS contents as well as PPARγ gene expression; while notably and negatively related to the expression of CPT-1 and HLS genes (p < 0.01). KF remarkably increased the abundance of Aerococcaceae, while reduced that of Alistipes finegoldii (p < 0.01).

CONCLUSIONS

Supplementation with KF achieves favorable effects on treating obesity, improving inflammatory response, metabolism, and intestinal barrier function, by regulating intestinal microfloral structure in HFD-fed mice.

Bifidobacterium pseudolongum in the Ceca of Rats Fed Hi-Maize Starch Has Characteristics of a Keystone Species in Bifidobacterial Blooms

Starches resistant to mammalian digestion are present in foods and pass to the large bowel, where they may be degraded and fermented by the microbiota. Increases in relative abundances of bifidobacteria (blooms) have been reported in rats whose diet was supplemented with Hi-Maize resistant starch. We determined that the bifidobacterial species present in the rat cecum under these circumstances mostly belonged to Bifidobacterium animalis However, cultures of B. animalis isolated from the rats failed to degrade Hi-Maize starch to any extent. In contrast, Bifidobacterium pseudolongum also detected in the rat microbiota had high starch-degrading ability. Transcriptional comparisons showed increased expression of a type 1 pullulanase, alpha-amylase, and glycogen debranching enzyme by B. pseudolongum when cultured in medium containing Hi-Maize starch. Maltose was released into the culture medium, and B. animalis cultures had shorter doubling times in maltose medium than did B. pseudolongum Thus, B. pseudolongum, which was present at a consistently low abundance in the microbiota, but which has extensive enzymatic capacity to degrade resistant starch, showed the attributes of a keystone species associated with the bifidobacterial bloom.IMPORTANCE This study addresses the microbiology and function of a natural ecosystem (the rat gut) using DNA-based observations and in vitro experimentation. The microbial community of the large bowel of animals, including humans, has been studied extensively through the use of high-throughput DNA sequencing methods and advanced bioinformatics analysis. These studies reveal the compositions and genetic capacities of microbiotas but not the intricacies of how microbial communities function. Our work, combining DNA sequence analysis and laboratory experiments with cultured strains of bacteria, revealed that the increased abundance of bifidobacteria in the rat gut, induced by feeding indigestible starch, involved a species that cannot itself degrade the starch (Bifidobacterium animalis) but cohabits with a species that can (Bifidobacterium pseudolongum). B. pseudolongum has the characteristics of a keystone species in the community because it had low abundance but high ability to perform a critical function, the hydrolysis of resistant starch.

Arabinoxylo-Oligosaccharides and Inulin Impact Inter-Individual Variation on Microbial Metabolism and Composition, Which Immunomodulates Human Cells

Fecal batch fermentations coupled to cocultures of epithelial cells and macrophages were used to compare how arabinoxylo-oligosaccharides (AXOS) and inulin modulate gut microbial activity and composition of three different human donors and subsequently the epithelial permeability and immune response. Both inulin and AXOS decreased the pH during incubation (-1.5 pH units), leading to increased productions of acetate, propionate, and butyrate. Differences in terms of metabolites production could be linked to specific microbial alterations at genus level upon inulin/AXOS supplementation (i.e., Bifidobacterium, Bacteroides, Prevotella and unclassified Erysipelotrichaceae), as shown by 16S-targeted Illumina sequencing. Both products stimulated gut barrier and immune function with increases in TEER, NF-KB, IL-10, and IL-6. Ingredients with different structures selectively modulate the microbiota of a specific donor leading to differential changes at metabolic level. The extent of this effect is donor specific and is linked to a final specific modulation of the host's immune system.

Gastroparesis and lipid metabolism-associated dysbiosis in Wistar-Kyoto rats

Altered gastric accommodation and intestinal morphology suggest impaired gastrointestinal (GI) transit may occur in the Wistar-Kyoto (WKY) rat strain, as common in stress-associated functional GI disorders. Because changes in GI transit can alter microbiota composition, we investigated whether these are altered in WKY rats compared with the resilient Sprague-Dawley (SD) rats under basal conditions and characterized plasma lipid and metabolite differences. Bead transit was tracked by X-ray imaging to monitor gastric emptying (4 h), small intestine (SI) transit (9 h), and large intestine transit (12 h). Plasma extracts were analyzed by lipid and hydrophilic interaction liquid chromatography (HILIC) and liquid chromatography-mass spectrometry (LC-MS). Cecal microbial composition was determined by Illumina MiSeq 16S rRNA amplicon sequencing and analysis using the QIIME pipeline. Stomach retention of beads was 77% for WKY compared with 35% for SD rats. GI transit was decreased by 34% (9 h) and 21% (12 h) in WKY compared with SD rats. Excluding stomach retention, transiting beads moved 29% further along the SI over 4-9 h for WKY compared with SD rats. Cecal Ruminococcus, Roseburia, and unclassified Lachnospiraceae genera were less abundant in WKY rats, whereas the minor taxa Dorea, Turicibacter, and Lactobacillus were higher. Diglycerides, triglycerides, phosphatidyl-ethanolamines, and phosphatidylserine were lower in WKY rats, whereas cholesterol esters and taurocholic acids were higher. The unexpected WKY rat phenotype of delayed gastric emptying, yet rapid SI transit, was associated with altered lipid and metabolite profiles. The delayed gastric emptying of the WKY phenotype suggests this rat strain may be useful as a model for gastroparesis.NEW & NOTEWORTHY This study reveals that the stress-prone Wistar-Kyoto rat strain has a baseline physiology of gastroparesis and rapid small intestine transit, together with metabolic changes consistent with lipid metabolism-associated dysbiosis, compared with nonstress-prone rats. This suggests that the Wistar-Kyoto rat strain may be an appropriate animal model for gastroparesis.

Key bacterial families (Clostridiaceae, Erysipelotrichaceae and Bacteroidaceae) are related to the digestion of protein and energy in dogs

BACKGROUND

Much of the recent research in companion animal nutrition has focussed on understanding the role of diet on faecal microbiota composition. To date, diet-induced changes in faecal microbiota observed in humans and rodents have been extrapolated to pets in spite of their very different dietary and metabolic requirements. This lack of direct evidence means that the mechanisms by which microbiota influences health in dogs are poorly understood. We hypothesised that changes in faecal microbiota correlate with physiological parameters including apparent macronutrient digestibility.

METHODS

Fifteen adult dogs were assigned to two diet groups, exclusively fed either a premium kibbled diet (kibble; K; n = 8) or a raw red meat diet (meat; M; n = 7) for nine weeks. Apparent digestibility of macronutrients (protein, fat, gross energy and dry matter), faecal weight, faecal health scores, faecal VFA concentrations and faecal microbial composition were determined. Datasets were integrated using mixOmics in R.

RESULTS

Faecal weight and VFA levels were lower and the apparent digestibility of protein and energy were higher in dogs on the meat diet. Diet significantly affected 27 microbial families and 53 genera in the faeces. In particular, the abundances of Bacteriodes, Prevotella, Peptostreptococcus and Faecalibacterium were lower in dogs fed the meat diet, whereas Fusobacterium, Lactobacillus and Clostridium were all more abundant.

DISCUSSION

Our results show clear associations of specific microbial taxa with diet composition. For example, Clostridiaceae, Erysipelotrichaceae and Bacteroidaceae were highly correlated to parameters such as protein and fat digestibility in the dog. By understanding the relationship between faecal microbiota and physiological parameters we will gain better insights into the effects of diet on the nutrition of our pets.

Inclusion of Konjac Flour in the Gestation Diet Changes the Gut Microbiota, Alleviates Oxidative Stress, and Improves Insulin Sensitivity in Sows

Although dietary fibers contribute to health and physiology primarily via the fermentative actions of the gut microbiota of the hosts, few studies have focused on how these interactions influence the metabolic status of sows. Here, the effects of inclusion of konjac flour (KF) in a gestation diet on oxidative stress status, insulin sensitivity, and gut microbiota were investigated to elucidate the correlation between the microbiota and metabolic changes in sows. Sows were assigned to either control or 2.2% KF dietary treatment during gestation. The gut microbiota population in sows during gestation and lactation was assessed by 16S rRNA gene sequencing. The oxidative stress parameters, homeostasis model assessment (HOMA) values, and fatty acids in the blood of sows were also assessed. Compared to the control diet group, KF significantly reduced the serum levels of reactive oxygen species (ROS) and 8-hydroxy-deoxyguanosine (8-OHdG) but increased the serum concentrations of glutathione peroxidase (GSH-Px) in sows on day 1 in lactation. Additionally, sows in the KF group had a lower HOMA insulin resistance value but a higher HOMA insulin sensitivity (HOMA-IS) value. KF induced changes in the gut microbial composition at the phylum and genus levels. The increased relative abundances of Akkermansia and Roseburia in the KF group were positively correlated with the HOMA-IS. Overall, dietary KF alleviated oxidative stress and improved insulin sensitivity of sows, and the changes in the gut microbiota in response to KF may have been correlated with the host metabolism response.

IMPORTANCE

To date, the effect of dietary fiber on metabolism responses and gut microbiota in sows has not been investigated. Here, KF supplementation of a gestation diet in sows was found to alleviate oxidative stress and to improve insulin sensitivity. Pyrosequencing analysis revealed that KF treatment induces changes in the gut microbiota composition at the phylum and genus levels. Moreover, the changes of gut microbiota in response to KF may be correlated with the host metabolism response.

Human Breast Milk and Infant Formulas Differentially Modify the Intestinal Microbiota in Human Infants and Host Physiology in Rats

BACKGROUND

In the absence of human breast milk, infant and follow-on formulas can still promote efficient growth and development. However, infant formulas can differ in their nutritional value.

OBJECTIVE

The objective of this study was to compare the effects of human milk (HM) and infant formulas in human infants and a weanling rat model.

METHODS

In a 3 wk clinical randomized controlled trial, babies (7- to 90-d-old, male-to-female ratio 1:1) were exclusively breastfed (BF), exclusively fed Synlait Pure Canterbury Stage 1 infant formula (SPCF), or fed assorted standard formulas (SFs) purchased by their parents. We also compared feeding HM or SPCF in weanling male Sprague-Dawley rats for 28 d. We examined the effects of HM and infant formulas on fecal short chain fatty acids (SCFAs) and bacterial composition in human infants, and intestinal SCFAs, the microbiota, and host physiology in weanling rats.

RESULTS

Fecal Bifidobacterium concentrations (mean log copy number ± SEM) were higher (P = 0.003) in BF (8.17 ± 0.3) and SPCF-fed infants (8.29 ± 0.3) compared with those fed the SFs (6.94 ± 0.3). Fecal acetic acid (mean ± SEM) was also higher (P = 0.007) in the BF (5.5 ± 0.2 mg/g) and SPCF (5.3 ± 2.4 mg/g) groups compared with SF-fed babies (4.3 ± 0.2 mg/g). Colonic SCFAs did not differ between HM- and SPCF-fed rats. However, cecal acetic acid concentrations were higher (P = 0.001) in rats fed HM (42.6 ± 2.6 mg/g) than in those fed SPCF (30.6 ± 0.8 mg/g). Cecal transcriptome, proteome, and plasma metabolite analyses indicated that the growth and maturation of intestinal tissue was more highly promoted by HM than SPCF.

CONCLUSIONS

Fecal bacterial composition and SCFA concentrations were similar in babies fed SPCF or HM. However, results from the rat study showed substantial differences in host physiology between rats fed HM and SPCF. This trial was registered at Shanghai Jiào tong University School of Medicine as XHEC-C-2012-024.

Effects of a Mediterranean Diet Intervention on Anti- and Pro-Inflammatory Eicosanoids, Epithelial Proliferation, and Nuclear Morphology in Biopsies of Normal Colon Tissue

This randomized trial evaluated the effects of intervention with either a Healthy Eating or a Mediterranean diet on colon biomarkers in 120 healthy individuals at increased colon cancer risk. The hypothesis was that eicosanoids and markers of proliferation would be favorably affected by the Mediterranean diet. Colon epithelial biopsy tissues and blood samples were obtained at baseline and after 6 mo of intervention. Colonic eicosanoid concentrations were evaluated by HPLC-MS-MS, and measures of epithelial proliferation and nuclear morphology were evaluated by image analysis of biopsy sections. There was little change in proinflammatory eicosanoids and in plasma cytokine concentrations with either dietary intervention. There was, however, a 50% increase in colonic prostaglandin E3 (PGE3), which is formed from eicosapentanoic acid, in the Mediterranean arm. Unlike PGE2, PGE3, was not significantly affected by regular use of non-steroidal anti-inflammatory drugs at baseline, and normal weight subjects had significantly higher colon PGE3 than overweight or obese subjects. Increased proliferation in the colon at baseline, by Ki67 labeling, was associated with morphological features that defined smaller nuclei in the epithelial cells, lower colon leukotriene concentrations and higher plasma cytokine concentrations. Dietary intervention had little effect on measures of epithelial proliferation or of nuclear morphology. The increase in PGE3 with a Mediterranean diet indicates that in normal colon, diet might affect protective pathways to a greater extent than proinflammatory and proliferative pathways. Hence, biomarkers from cancer models might not be relevant in a true prevention setting.