Effects of taurine on gut microbiota and metabolism in mice

Feeding Aspergillus protease preparation combined with adequate protein diet to rats increases levels of cecum gut-protective amino acids, partially linked to Bifidobacterium and Lactobacillus

Our recent study indicated that dietary Aspergillus oryzae-derived protease preparation (AP), through its enzymatic activity, exerted a bifidogenic effect in rats. We hypothesized that dietary AP links to protein degradation and subsequently elevates gut-protective amino acids (AAs) in rats fed adequate protein diet. In this study, dietary AP markedly increased the relative abundance of Bifidobacterium and Lactobacillus and the levels of free threonine, alanine, proline, taurine, ornithine, phenylalanine, cystine, and γ-aminobutyric acid in the cecum contents of rats fed with an adequate protein diet, but not in those fed with a low-protein diet. The elevated AAs, except ornithine and phenylalanine, potentially have gut-related health benefits. Some of the AP-modulated free AAs appeared to be associated with the relative abundance of Bifidobacterium and Lactobacillus. Thus, AP combined with adequate protein diet is likely to increase the levels of cecum beneficial free AAs, which is partially associated with the relative abundance of the probiotics.

Sucrose metabolism alters Lactobacillus plantarum survival and interactions with the microbiota in the digestive tract

We investigated whether sucrose metabolism by probiotic Lactobacillus plantarum influences the intestinal survival and microbial responses to this organism when administered to mice fed a sucrose-rich, Western diet. A L. plantarum mutant unable to metabolize sucrose was constructed by deleting scrB, coding for beta-fructofuranosidase, in a rifampicin-resistant strain of L. plantarum NCIMB8826. The ScrB deficient mutant survived in 8-fold higher numbers compared to the wild-type strain when measured 24 h after administration on two consecutive days. According to 16S rRNA marker gene sequencing, proportions of Faecalibacterium and Streptococcus were elevated in mice fed the L. plantarum ΔscrB mutant. Metagenome predictions also indicated those mice contained a higher abundance of lactate dehydrogenases. This was further supported by a trend in elevated fecal lactate concentrations among mice fed the ΔscrB mutant. L. plantarum also caused other changes to the fecal metabolomes including higher concentrations of glycerol in mice fed the ΔscrB mutant and increased uracil, acetate and propionate levels among mice fed the wild-type strain. Taken together, these results suggest that sucrose metabolism alters the properties of L. plantarum in the digestive tract and that probiotics can differentially influence intestinal metabolomes via their carbohydrate consumption capabilities.

Alterations in the gut microbiome and metabolism with coronary artery disease severity

BACKGROUND

Coronary artery disease (CAD) is associated with gut microbiota alterations in different populations. Gut microbe-derived metabolites have been proposed as markers of major adverse cardiac events. However, the relationship between the gut microbiome and the different stages of CAD pathophysiology remains to be established by a systematic study.

RESULTS

Based on multi-omic analyses (sequencing of the V3-V4 regions of the 16S rRNA gene and metabolomics) of 161 CAD patients and 40 healthy controls, we found that the composition of both the gut microbiota and metabolites changed significantly with CAD severity. We identified 29 metabolite modules that were separately classified as being positively or negatively correlated with CAD phenotypes, and the bacterial co-abundance group (CAG) with characteristic changes at different stages of CAD was represented by Roseburia, Klebsiella, Clostridium IV and Ruminococcaceae. The result revealed that certain bacteria might affect atherosclerosis by modulating the metabolic pathways of the host, such as taurine, sphingolipid and ceramide, and benzene metabolism. Moreover, a disease classifier based on differential levels of microbes and metabolites was constructed to discriminate cases from controls and was even able to distinguish stable coronary artery disease from acute coronary syndrome accurately.

CONCLUSION

Overall, the composition and functions of the gut microbial community differed from healthy controls to diverse coronary artery disease subtypes. Our study identified the relationships between the features of the gut microbiota and circulating metabolites, providing a new direction for future studies aiming to understand the host-gut microbiota interplay in atherosclerotic pathogenesis.

NMR metabolomics reveals effects of Cryptosporidium infections on host cell metabolome

Background

Cryptosporidium is an important gut microbe whose contributions towards infant and immunocompromise patient mortality rates are steadily increasing. Over the last decade, we have seen the development of various tools and methods for studying Cryptosporidium infection and its interactions with their hosts. One area that is sorely overlooked is the effect infection has on host metabolic processes.

Results

Using a ¹H nuclear magnetic resonance approach to metabolomics, we have explored the nature of the mouse gut metabolome as well as providing the first insight into the metabolome of an infected cell line. Statistical analysis and predictive modelling demonstrated new understandings of the effects of a Cryptosporidium infection, while verifying the presence of known metabolic changes. Of note is the potential contribution of host derived taurine to the diarrhoeal aspects of the disease previously attributed to a solely parasite-based alteration of the gut environment, in addition to other metabolites involved with host cell catabolism.

Conclusion

This approach will spearhead our understanding of the Cryptosporidium-host metabolic exchange and provide novel targets for tackling this deadly parasite.

Seafood intake and the development of obesity, insulin resistance and type 2 diabetes

We provide an overview of studies on seafood intake in relation to obesity, insulin resistance and type 2 diabetes. Overweight and obesity development is for most individuals the result of years of positive energy balance. Evidence from intervention trials and animal studies suggests that frequent intake of lean seafood, as compared with intake of terrestrial meats, reduces energy intake by 4–9 %, sufficient to prevent a positive energy balance and obesity. At equal energy intake, lean seafood reduces fasting and postprandial risk markers of insulin resistance, and improves insulin sensitivity in insulin-resistant adults. Energy restriction combined with intake of lean and fatty seafood seems to increase weight loss. Marine n-3 PUFA are probably of importance through n-3 PUFA-derived lipid mediators such as endocannabinoids and oxylipins, but other constituents of seafood such as the fish protein per se, trace elements or vitamins also seem to play a largely neglected role. A high intake of fatty seafood increases circulating levels of the insulin-sensitising hormone adiponectin. As compared with a high meat intake, high intake of seafood has been reported to reduce plasma levels of the hepatic acute-phase protein C-reactive protein level in some, but not all studies. More studies are needed to confirm the dietary effects on energy intake, obesity and insulin resistance. Future studies should be designed to elucidate the potential contribution of trace elements, vitamins and undesirables present in seafood, and we argue that stratification into responders and non-responders in randomised controlled trials may improve the understanding of health effects from intake of seafood.

Effect of Taurine on Thymus Differentiation of Dex-Induced Immunosuppressive Mice

Taurine (2-aminoethanesulfonic acid) has positive effects on the formation of immune systems. In this study, we evaluated the effects of taurine on the development of T lymphocyte subpopulations in thymus of immunosuppresive mice. The immunosuppressed mice model was established by intraperitoneal injection of dexamethasone (Dex) for 7 days. Mice (male, Kunming strain) were randomly divided into three groups, the normal control group (Cont.), the Dex-induced immunosuppressive model group (Dex + PBS), and the taurine intervention group (Dex + TAU). Taurine was administered at a dose of 200 mg/kg for 30 days or until euthanasia. Total cell numbers in the thymi of mice were evaluated by cell count, and the flow cytometry was used to determine the proportion of different cell subsets. Our results showed that the size and weight of thymi of Dex + PBS group were significantly smaller than those of Cont. group, and taurine administration efficiently increased the thymus index. Taurine also significantly increased the number of CD4- CD8- double negative (DN), CD4+ CD8+ double positive (DP), CD4+ single positive (CD4+) and CD8+ SP (CD8+) cells compared with the Dex + PBS group, but did not affect the CD4+/CD8+ cell ratio in thymus of Dex-induced immunoseppressive mice. Our results suggested that taurine has a positive effect on thymus differentiation in Dex-induced immunosuppressive mice.

Effects of dietary taurine on growth, non-specific immunity, anti-oxidative properties and gut immunity in the Chinese mitten crab Eriocheir sinensis

Taurine has been widely researched as a growth-promoting additive or as an antioxidant in aquatic animals because of its multiple functions, however, few studies have explored its effects on crustacean in spite of the occurrence of serious diseases. We studied the effects of taurine supplementation on the growth, non-specific immunity, anti-oxidative properties and gut immunity of the Chinese mitten crab Eriocheir sinensis. Healthy crabs (8.0 ± 0.5 g) were fed diets supplemented with taurine at 0% (control), 0.2%, 0.4%, 0.8%, and 1.6% for 65 days. At the end of this 65 days feeding trial, the final weight, weight gain, specific growth rate, and feed conversion ratio were best in crabs fed the 0.4% taurine diet, followed by that in those fed the 0.8% taurine diet; the parameters were worst for the control group. Carapace length (CL) and carapace width (CW) were significantly increased in the crab fed the 0.4% and 0.8% taurine diet than that of the other three groups. Total haemocyte count (THC) and acid phosphatase (ACP) activity were significantly higher in the crab fed the 0.8% taurine diet than in those belonging to the other groups, the crabs fed the 0.4% taurine diet had the highest phenoloxidase (PO), lysozyme (LZM), and alkaline phosphatase (AKP) activities, however, there was no obvious change in their haemocyanin (Hc) content. According to superoxide dismutase (SOD), glutathione Peroxidase (GSH-PX), total anti-oxidant capacity (T-AOC) activities and malondialdehyde (MDA) content, the antioxidant capacity was significantly induced by taurine diet, while was higher in crabs fed 0.4 %-0.8% taurine diet than that of the other groups. Taurine supplementation significantly up-regulated the expression of gut immune genes (EsToll2, EsRelish) and antimicrobial peptides (EsALF1, EsALF2, EsCrus1, EsCrus2) in crabs gut fed the 0.2-0.8% taurine diet group compared to control. Thus, these study results indicate that dietary taurine is important for improving growth, regulating immunity, and enhancing the antioxidant capacity in crabs, with the recommended optimum dietary allowance being 0.4 %-0.8% taurine for E. sinensis.

Taurine Inhibits Kupffer Cells Activation Induced by Lipopolysaccharide in Alcoholic Liver Damaged Rats

Taurine, a β free amino-acid, takes various biological functions including maintain the normal hepatic structure and function. In this study, the regulation mechanism of taurine on lipopolysaccharide (LPS) induced activation of Kupffer cells (KC) in the liver of rats with alcoholic liver disease (ALD) were explored. Male wistar rats were intragastrically administered with alcohol and pyrazole, and ate high-fat diet in order to establish ALD model. Taurine were administered in drinking water simultaneous with and after ALD model establishment. The preventive trial was lasted for 12 weeks, while the curative trial was lasted for 4 weeks. Finally, blood and liver were collected in order to detect the concentrations of plasma LPS and hepatic tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). Hepatic total RNA were extracted, gene expressions of LPS binding protein (LBP), leukocyte differentiation antigen 14 (CD14), toll-like receptors (TLR4), nuclear transcription factor (NF-κB) and TNF-α were detected by semi-quantitative RT-PCR. The results showed significant elevated levels of plasma LPS, hepatic TNF-α, IL-1β and IL-6 in ALD rats (P < 0.05), and heightened gene expressions of LBP, CD14, TLR4, NF-κB and TNF-α (P < 0.05); Taurine no matter administered preventively or curatively can reduce the levels of plasma LPS, hepatic TNF-α, IL-1β, IL-6, and down-regulate the gene expressions of LBP, CD14, TLR4, NF-κB and TNF-α. The results demonstrated that taurine can prevent and cure ALD by reducing the production and transformation of LPS as well as inhibiting the opening and the transmission of LPS induced KC activation and the downstream signaling pathway.

The gut microbiome as a driver of individual variation in cognition and functional behaviour

Research into proximate and ultimate mechanisms of individual cognitive variation in animal populations is a rapidly growing field that incorporates physiological, behavioural and evolutionary investigations. Recent studies in humans and laboratory animals have shown that the enteric microbial community plays a central role in brain function and development. The 'gut-brain axis' represents a multi-directional signalling system that encompasses neurological, immunological and hormonal pathways. In particular it is tightly linked with the hypothalamic-pituitary-adrenal axis (HPA), a system that regulates stress hormone release and influences brain development and function. Experimental examination of the microbiome through manipulation of diet, infection, stress and exercise, suggests direct effects on cognition, including learning and memory. However, our understanding of these processes in natural populations is extremely limited. Here, we outline how recent advances in predominantly laboratory-based microbiome research can be applied to understanding individual differences in cognition. Experimental manipulation of the microbiome across natal and adult environments will help to unravel the interplay between cognitive variation and the gut microbial community. Focus on individual variation in the gut microbiome and cognition in natural populations will reveal new insight into the environmental and evolutionary constraints that drive individual cognitive variation.This article is part of the theme issue 'Causes and consequences of individual differences in cognitive abilities'.

The inflammasomes, immune guardians at defence barriers

As a result of its strategic location, the epithelium is constantly exposed to a wide variety of pathogen and danger signals. Traditionally, the epithelium has been perceived as a defensive but passive barrier; however, it has now become evident that the epithelium senses and actively responds to these signals in order to maintain barrier homeostasis and contributes to the inflammatory response. One way it does this is by producing pro-inflammatory cytokines including interleukin-1β (IL-1β) and IL-18. These two cytokines are synthesized as inactive precursors, the maturation of which is mediated by pro-inflammatory caspases after the activation and assembly of macromolecular complexes called inflammasomes. Epithelial cells express a large panel of inflammasome components, and although the molecular mechanisms underlying the activation of these complexes in haematopoietic cells are well understood, how epithelial cells react to danger signals to activate the inflammasome remains unclear. We review and discuss how different inflammasomes contribute to barrier homeostasis and inflammation at several barrier sites, their mechanisms and how their aberrant regulation contributes to disease at the different epithelia.

Links between Dietary Protein Sources, the Gut Microbiota, and Obesity

The association between the gut microbiota and obesity is well documented in both humans and in animal models. It is also demonstrated that dietary factors can change the gut microbiota composition and obesity development. However, knowledge of how diet, metabolism and gut microbiota mutually interact and modulate energy metabolism and obesity development is still limited. Epidemiological studies indicate an association between intake of certain dietary protein sources and obesity. Animal studies confirm that different protein sources vary in their ability to either prevent or induce obesity. Different sources of protein such as beans, vegetables, dairy, seafood, and meat differ in amino acid composition. Further, the type and level of other factors, such as fatty acids and persistent organic pollutants (POPs) vary between dietary protein sources. All these factors can modulate the composition of the gut microbiota and may thereby influence their obesogenic properties. This review summarizes evidence of how different protein sources affect energy efficiency, obesity development, and the gut microbiota, linking protein-dependent changes in the gut microbiota with obesity.

Balancing Herbal Medicine and Functional Food for Prevention and Treatment of Cardiometabolic Diseases through Modulating Gut Microbiota

It has become apparent that gut microbiota is closely associated with cardiometabolic diseases (CMDs), and alteration in microbiome compositions is also linked to the host environment. Next generation sequencing (NGS) has facilitated in-depth studies on the effects of herbal medicine and functional food on gut microbiota. Both herbal medicine and functional food contain fiber, polyphenols and polysaccharides, exerting prebiotics-like activities in the prevention and treatment of CMDs. The administrations of herbal medicine and functional food lead to increased the abundance of phylum Bacteroidetes, and genus Akkermansia, Bifidobacteria, Lactobacillus, Bacteroides and Prevotella, while reducing phylum Firmicutes and Firmicutes/Bacteroidetes ratio in gut. Both herbal medicine and functional food interact with gut microbiome and alter the microbial metabolites including short-chain fatty acids (SCFAs), bile acids (BAs) and lipopolysaccharides (LPS), which are now correlated with metabolic diseases such as type 2 diabetes (T2D), obesity and non-alcoholic fatty liver disease (NAFLD). In addition, trimethylamine (TMA)-N-oxide (TMAO) is recently linked to atherosclerosis (AS) and cardiovascular disease (CVD) risks. Moreover, gut-organs axes may serve as the potential strategy for treating CMDs with the intervention of herbal medicine and functional food. In summary, a balance between herbal medicine and functional food rich in fiber, polyphenols and polysaccharides plays a vital role in modulating gut microbiota (phylum Bacteroidetes, Firmicutes and Firmicutes/Bacteroidetes ratio, and genus Akkermansia, Bifidobacteria, Lactobacillus, Bacteroides and Prevotella) through SCFAs, BAs, LPS and TMAO signaling regarding CMDs. Targeting gut-organs axes may serve as a new therapeutic strategy for CMDs by herbal medicine and functional food in the future. This review aims to summarize the balance between herbal medicine and functional food utilized for the prevention and treatment of CMDs through modulating gut microbiota.

Other Helicobacters, gastric and gut microbiota

The current article is a review of the most important and relevant literature published in 2016 and early 2017 on non-Helicobacter pylori Helicobacter infections in humans and animals, as well as interactions between H. pylori and the microbiota of the stomach and other organs. Some putative new Helicobacter species were identified in sea otters, wild boars, dogs, and mice. Many cases of Helicobacter fennelliae and Helicobacter cinaedi infection have been reported in humans, mostly in immunocompromised patients. Mouse models have been used frequently as a model to investigate human Helicobacter infection, although some studies have investigated the pathogenesis of Helicobacters in their natural host, as was the case for Helicobacter suis infection in pigs. Our understanding of both the gastric and gut microbiome has made progress and, in addition, interactions between H. pylori and the microbiome were demonstrated to go beyond the stomach. Some new approaches of preventing Helicobacter infection or its related pathologies were investigated and, in this respect, the probiotic properties of Saccharomyces, Lactobacillus and Bifidobacterium spp. were confirmed.

Taurine does not affect the composition, diversity, or metabolism of human colonic microbiota simulated in a single-batch fermentation system

Accumulating evidence suggests that dietary taurine (2-aminoethanesulfonic acid) exerts beneficial anti-inflammatory effects in the large intestine. In this study, we investigated the possible impact of taurine on human colonic microbiota using our single-batch fermentation system (Kobe University Human Intestinal Microbiota Model; KUHIMM). Fecal samples from eight humans were individually cultivated with and without taurine in the KUHIMM. The results showed that taurine remained largely undegraded after 30 h of culturing in the absence of oxygen, although some 83% of the taurine was degraded after 30 h of culturing under aerobic conditions. Diversity in bacterial species in the cultures was analyzed by 16S rRNA gene sequencing, revealing that taurine caused no significant change in the diversity of the microbiota; both operational taxonomic unit and Shannon-Wiener index of the cultures were comparable to those of the respective source fecal samples. In addition, principal coordinate analysis indicated that taurine did not alter the composition of bacterial species, since the 16S rRNA gene profile of bacterial species in the original fecal sample was maintained in each of the cultures with and without taurine. Furthermore, metabolomic analysis revealed that taurine did not affect the composition of short-chain fatty acids produced in the cultures. These results, under these controlled but artificial conditions, suggested that the beneficial anti-inflammatory effects of dietary taurine in the large intestine are independent of the intestinal microbiota. We infer that dietary taurine may act directly in the large intestine to exert anti-inflammatory effects.

Tissue-Associated Bacterial Alterations in Rectal Carcinoma Patients Revealed by 16S rRNA Community Profiling

Sporadic and inflammatory forms of colorectal cancer (CRC) account for more than 80% of cases. Recent publications have shown mechanistic evidence for the involvement of gut bacteria in the development of both CRC-forms. Whereas, colon and rectal cancer have been routinely studied together as CRC, increasing evidence show these to be distinct diseases. Also, the common use of fecal samples to study microbial communities may reflect disease state but possibly not the tumor microenvironment. We performed this study to evaluate differences in bacterial communities found in tissue samples of 18 rectal-cancer subjects when compared to 18 non-cancer controls. Samples were collected during exploratory colonoscopy (non-cancer group) or during surgery for tumor excision (rectal-cancer group). High throughput 16S rRNA amplicon sequencing of the V4-V5 region was conducted on the Ion PGM platform, reads were filtered using Qiime and clustered using UPARSE. We observed significant increases in species richness and diversity in rectal cancer samples, evidenced by the total number of OTUs and the Shannon and Simpson indexes. Enterotyping analysis divided our cohort into two groups, with the majority of rectal cancer samples clustering into one enterotype, characterized by a greater abundance of Bacteroides and Dorea. At the phylum level, rectal-cancer samples had increased abundance of candidate phylum OD1 (also known as Parcubacteria) whilst non-cancer samples had increased abundance of Planctomycetes. At the genera level, rectal-cancer samples had higher abundances of Bacteroides, Phascolarctobacterium, Parabacteroides, Desulfovibrio, and Odoribacter whereas non-cancer samples had higher abundances of Pseudomonas, Escherichia, Acinetobacter, Lactobacillus, and Bacillus. Two Bacteroides fragilis OTUs were more abundant among rectal-cancer patients seen through 16S rRNA amplicon sequencing, whose presence was confirmed by immunohistochemistry and enrichment verified by digital droplet PCR. Our findings point to increased bacterial richness and diversity in rectal cancer, along with several differences in microbial community composition. Our work is the first to present evidence for a possible role of bacteria such as B. fragilis and the phylum Parcubacteria in rectal cancer, emphasizing the need to study tissue-associated bacteria and specific regions of the gastrointestinal tract in order to better understand the possible links between the microbiota and rectal cancer.