Quantification of butyryl CoA:acetate CoA-transferase genes reveals different butyrate production capacity in individuals according to diet and age

Gut microbiome related to metabolic diseases after moderate-to-vigorous intensity exercise

Background objectives

The purpose of this study is to investigate changes in gut microbiota related to metabolic diseases after moderate and high-intensity exercise. A total of 24 participants were divided into three groups: Non-Exercise Group (NEG, n = 8, 28.6 ± 5.3 years, 176.0 ± 7.8 cm, 81.3 ± 14.6 kg), Moderate Intensity Exercise Group (MIEG, n = 8, 26.5 ± 3.3 years, 176.9 ± 5.0 cm, 75.4 ± 9.5 kg), and Vigorous Intensity Exercise Group (VIEG, n = 8, 30.6 ± 5.9 years, 174.2 ± 3.5 cm, 77.8 ± 12.2 kg).

Methods

The participants were selected by assessing physical activity, gut health status, presence of diseases, recent disease diagnoses, and dietary disorders. Those who reported any presence disease or recent disease diagnosis were excluded from the current study. Stool samples were collected after a 10-h fast for gut microbiome analysis. MIEG participants trained at 40-59 % heart rate reserve (HRR) for at least 150 min per week, while VIEG participants trained at ≥ 60 % HRR for at least 90 min per week. After 4 weeks, all participants provided stool samples for gut microbiome analysis.Data analysis was conducted using the Wilcoxon test, with statistical significance set at ≤ 0.05.

Results

The results indicated an increase in Prevotella in MIEG, while Veillonella, Dorea_formicigenerans, and Dorea_longicatena exhibited a decrease (p < 0.05). In VIEG, there was an increase in Bacteroides, Butyricimonas, Odoribacter, and Alistipes (p < 0.05).

Conclusion

These modified microbial groups were associated with factors related to metabolic diseases, including inflammatory bowel disease, obesity, colorectal cancer, diabetes, hypertension, metabolic liver diseases, and ischemic heart diseases. Additional research is essential to delve into the relationship between exercise and these alterations in the microbiome.

Effects of sanitary conditions with lipopolysaccharide injection and dietary valine supplementation on growth performance, immune response, bacterial profile, and microbial metabolites in weaned pigs

This study investigated the effects of dietary L-valine (Val) supplementation and sanitary conditions with lipopolysaccharide injection on growth performance, immune response, and intestinal bacterial profiles and metabolites in weaned pigs. Thirty-two weaned pigs (6.98 ± 0.47 kg) were randomly assigned to treatments in a 2 × 2 factorial arrangement based on dietary Val levels and sanitary conditions (low or high). The pigs were fed either a basal diet containing the standard levels of Val suggested by (NRC), (2012) or a basal diet supplemented with 0.1% L-Val. A room designated as a high sanitary room was washed weekly, whereas the designated low sanitary room was not washed throughout the experiment and 5 kg of manure from the nursery pig barn was spread on the pen floors on day 1. All data were analysed using a mixed procedure of SAS, with the individual pen as the experimental unit. The pigs raised in low sanitary conditions exhibited a lower (p < 0.05) average daily gain, average daily feed intake, and gain-to-feed ratio and a higher (p < 0.05) incidence of diarrhoea than those raised in high sanitary conditions during the 14-d experimental period. The pigs in the low sanitary group also had a lower (p < 0.05) concentration of butyrate in the jejunum and a higher (p < 0.05) concentration of NH3-N in the colon than those in the high sanitary group. Dietary Val supplementation was reduced (p < 0.05) plasma interleukin (IL)-1β and IL-1 receptor antagonist concentrations as well as isovalerate and NH3-N concentrations in the colon, regardless of sanitary conditions. Interactions between dietary Val supplementation and sanitary conditions were observed in the abundances of mRNA-encoding β-defensins 113, 125 and 129 (p < 0.05). In conclusion, dietary Val supplementation beneficially modulates inflammatory responses and microbial metabolites regardless of sanitary conditions while transcriptional levels of β-defensins are regulated by dietary Val supplementation in a manner dependent on housing hygiene conditions.

Microbiome and physical activity

Regular physical activity promotes health benefits and contributes to develop the individual biological potential. Chronical physical activity performed at moderate and high-intensity is the intensity more favorable to produce health development in athletes and improve the gut microbiota balance. The athletic microbiome is characterized by increased microbial diversity and abundance as well as greater phenotypic versatility. In addition, physical activity and microbiota composition have bidirectional effects, with regular physical activity improving microbial composition and microbial composition enhancing physical performance. The improvement of physical performance by a healthy microbiota is related to different phenotypes: i) efficient metabolic development, ii) improved regulation of intestinal permeability, iii) favourable modulation of local and systemic inflammatory and efficient immune responses, iv) efective regulation of systemic pH and, v) protection against acute stressful events such as environmental exposure to altitude or heat. The type of sport, both intensity or volume characteristics promote microbiota specialisation. Individual assessment of the state of the gut microbiota can be an effective biomarker for monitoring health in the medium to long term. The relationship between the microbiota and the rest of the body is bidirectional and symbiotic, with a full connection between the systemic functions of the nervous, musculoskeletal, endocrine, metabolic, acid-base and immune systems. In addition, circadian rhythms, including regular physical activity, directly influence the adaptive response of the microbiota. In conclusion, regular stimuli of moderate- and high-intensity physical activity promote greater diversity, abundance, resilience and versatility of the gut microbiota. This effect is highly beneficial for human health when healthy lifestyle habits including nutrition, hydration, rest, chronoregulation and physical activity.

Soy sauce-like seasoning enhances the growth of Agathobacter rectalis and the production of butyrate, propionate, and lactate

The short-chain fatty acids responsible for gut homeostasis are volatile fatty acids produced by commensal bacteria in the gut as fermentation products from undigested food components. Among the short-chain fatty acids, butyrate is important for maintaining intestinal tract anaerobic conditions, promoting epithelial barrier functions, and inducing regulatory T cells that suppress inflammatory bowel disease and allergic diarrhea. However, the type of food-derived molecular components and mechanisms by which they regulate the growth and butyrate production of butyrate-producing bacteria are not clearly understood. Agathobacter rectalis is a butyrate-producing bacterium highly colonized in the gut of the Japanese population. In this study, we investigated the effects on A. rectalis of a soy sauce-like seasoning made by brewing with a low salt concentration. The soy sauce-like seasoning promoted the growth of A. rectalis 2.6-fold. An ethanol precipitate prepared from the soy sauce-like seasoning was critical for promoting the growth of A. rectalis and the production of butyrate, propionate, and lactate. Fourier transform infrared spectroscopy (FT-IR) analysis suggested that polysaccharides were active ingredients in the ethanol precipitate of the soy sauce-like seasoning. Inulin, a representative prebiotic with effects against butyrate-producing bacteria, had a limited effect on the growth of A. rectalis compared with the soy sauce-like seasoning. Our results indicate that polysaccharides in a soy sauce-like seasoning contributed to the growth of A. rectalis and enhanced production of butyrate, propionate, and lactate.

Microbiota-derived short-chain fatty acids functions in the biology of B lymphocytes: From differentiation to antibody formation

Gut bacteria produce various metabolites from dietary fiber, the most abundant of which are short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate. Many biological functions, such as host metabolism and the immune system, are regulated by SCFAs because they act on a wide variety of cell types. A growing body of documents has shown that microbiota SCFAs directly regulate B-cell growth, proliferation, and immunoglobulin (Ig) production. As histone deacetylase (HDAC) inhibitors, SCFAs alter gene expression to enhance the expression of critical regulators of B cell growth. In particular, microbiota SCFAs increase the production of acetyl coenzyme A (acetyl-CoA), adenosine triphosphate (ATP), and fatty acids in B cells, which provide the energy and building blocks needed for the growth of plasma B cells. SCFAs play a significant role in promoting the involvement of B cells in host immunity during both homeostatic conditions and disease states. In this context, SCFAs stimulate B-cell activation and promote the differentiation of plasma B cells in response to B cell receptor (BCR)-activating antigens or co-stimulatory receptor ligands. The result may be increased production of IgA. Microbiota SCFAs were found to lower both overall and antigen-specific IgE levels, indicating their potential to mitigate IgE-related allergic reactions, much like their effect on class-switch recombination (CSR) towards IgG and IgA. Therefore, in the future, the therapeutic advantage should be to use specific and diffusible chemicals, such as SCFAs, which show a strong immunoregulatory function of B cells. This review focuses on the role of microbiota-produced SCFAs in regulating B cell development and antibody production, both in health and diseases.

Gut microbiota short-chain fatty acids and their impact on the host thyroid function and diseases

Thyroid disorders are clinically characterized by alterations of L-3,5,3',5'-tetraiodothyronine (T4), L-3,5,3'-triiodothyronine (T3), and/or thyroid-stimulating hormone (TSH) levels in the blood. The most frequent thyroid disorders are hypothyroidism, hyperthyroidism, and hypothyroxinemia. These conditions affect cell differentiation, function, and metabolism. It has been reported that 40% of the world's population suffers from some type of thyroid disorder and that several factors increase susceptibility to these diseases. Among them are iodine intake, environmental contamination, smoking, certain drugs, and genetic factors. Recently, the intestinal microbiota, composed of more than trillions of microbes, has emerged as a critical player in human health, and dysbiosis has been linked to thyroid diseases. The intestinal microbiota can affect host physiology by producing metabolites derived from dietary fiber, such as short-chain fatty acids (SCFAs). SCFAs have local actions in the intestine and can affect the central nervous system and immune system. Modulation of SCFAs-producing bacteria has also been connected to metabolic diseases, such as obesity and diabetes. In this review, we discuss how alterations in the production of SCFAs due to dysbiosis in patients could be related to thyroid disorders. The studies reviewed here may be of significant interest to endocrinology researchers and medical practitioners.

Lactobacillus rhamnosus GG and butyrate supplementation in rats with bone cancer reduces mechanical allodynia and increases expression of μ-opioid receptor in the spinal cord

Introduction

Chronic cancer pain is one of the most unbearable symptoms for the patients with advanced cancer. The treatment of cancer pain continues to possess a major challenge. Here, we report that adjusting gut microbiota via probiotics can reduce bone cancer pain (BCP) in rats.

Methods

The model of BCP was produced by tumor cell implantation (TCI) to the tibia in rats. Continuous feeding of Lactobacillus rhamnosus GG (LGG) was used to modulate the gut microbiota. Mechanical allodynia, bone destruction, fecal microbiota, and neurochemical changes in the primary dorsal root ganglion (DRG) and the spinal dorsal horn (DH) were assessed.

Results

LGG supplementation (10⁹ CFU/rat/day) delayed the production of BCP for 3-4 days and significantly alleviated mechanical allodynia within the first 2 weeks after TCI. TCI-induced proinflammatory cytokines TNF-α and IL-β in the DH, and TCI-induced bone destruction in the tibia were both significantly reduced following LGG supplementation examined on day 8 after TCI. Meanwhile, we found that LGG supplementation, in addition to inhibiting TCI-induced pain, resulted in a significantly increased expression of the μ-opioid receptor (MOR) in the DH, but not in the DRG. LGG supplementation significantly potentiated the analgesic effect of morphine. Furthermore, LGG supplementation led to an increase in butyrate levels in the feces and serum and a decrease in histone deacetylase 2 (HDAC2) expression in the DH. Feeding TCI-rats with sodium butyrate solution alone, at a dose of 100 mg/kg, resulted in decreased pain, as well as decreased HDAC2 expression and increased MOR expression in the DH. The increased expression of MOR and decreased HDAC2 were also observed in neuro-2a cells when we treated the cells with serum from TCI rats with supplementation of LGG or sodium butyrate.

Discussion

This study provides evidence that reshaping the gut microbiota with probiotics LGG can delay the onset of cancer pain. The butyrate-HDAC2-MOR pathway may be the underlying mechanism for the analgesic effect of LGG. These findings shed light on an effective, safe, and non-invasive approach for cancer pain control and support the clinical implication of probiotics supplementation for patients with BCP.

Meat Consumption and Gut Microbiota: a Scoping Review of Literature and Systematic Review of Randomized Controlled Trials in Adults

Emerging research indicates the importance of gut microbiota in mediating the relationship between meat intake and human health outcomes. We aimed to assess the state of available scientific literature on meat intake and gut microbiota in humans (PROSPERO, International Prospective Register of Systematic Reviews, CRD42020135649). We first conducted a scoping review to identify observational and interventional studies on this topic. Searches were performed for English language articles using PubMed, Cochrane Library, Scopus, and CINAHL (Cumulated Index to Nursing and Allied Health Literature) databases from inception to August 2021 and using keywords related to meat (inclusive of mammalian, avian, and aquatic subtypes) and gut microbiota. Of 14,680 records, 85 eligible articles were included in the scoping review, comprising 57 observational and 28 interventional studies. One prospective observational study and 13 randomized controlled trials (RCTs) were identified in adults without diagnosed disease. We included the 13 RCTs, comprising 18 comparisons, in the systematic review to assess the effects of higher and lower intakes of total meat and meat subtypes on the gut microbiota composition. The bacterial composition was differentially affected by consuming diets with and without meat or with varied meat subtypes. For example, higher meat intake tended to decrease population sizes of genera Anerostipes and Faecalibacterium, but it increased the population size of Roseburia across studies. However, the magnitude and directionality of most microbial responses varied, with inconsistent patterns of responses across studies. The data were insufficient for comparison within or between meat subtypes. The paucity of research, especially among meat subtypes, and heterogeneity of findings underscore the need for more well-designed prospective studies and full-feeding RCTs to address the relationships between and effects of consuming total meat and meat subtypes on gut microbiota, respectively.

Physical activity induced alterations of gut microbiota in humans: a systematic review

Background

Gut microbiota is considered to have a great impact on human health and disease. While it is widely recognized that the gut microbiota of healthy individuals differs from those with obesity, inflammatory bowel disease, metabolic syndrome, and other chronic diseases, the alterations of gut microbiota with physical activity are not fully understood. Accordingly, we performed this systematic review to address the question regarding the effects of mild and intense exercise on the gut microbiota in humans.

Methods

The comparative analyses of gut microbiota were conducted following the PRISMA protocol to determine the differences in the active vs. non-active individuals (phenotypes) (n = 11), including the influence of physical activity intervention on the human gut microbiota (n = 13); the differences in the gut microbiota of athletes vs. non-athletes (n = 8); and the microbiota status at different stages of athletic performance or intervention (n = 7), with various of physical activities, sport disciplines, and activity duration. Literature searches were completed using four databases: PubMed, Web of Science, Scopus, and EBSCO, and 2090 articles were retrieved by using appropriate keywords. The low heterogeneity of the studies hasn’t allowed us to prepare a meta-analysis. After excluding 2052 articles, we ultimately selected 38 articles that met the eligibility criteria for this review.

Results

The data analyses revealed that in non-athletes rising physical activity markedly influenced the relative abundance of short-chain fatty acid (SCFA). Aerobic training that lasted 60 min, and physical activity that characterized 60% HRmax or more also influenced beta diversity indexes. The results showed that athletes harbor a more diverse type of intestinal microflora than non-athletes, but with a relatively reduced abundance of SCFA- and lactic acid-producing bacteria, thereby suggesting an adverse effect of intense exercise on the population of gut microbiota.

Conclusion

It is concluded that the level of physical activity modulates the gastrointestinal microbiota in humans. For a long period, increasing the intensity and volume of exercise may lead to gut dysbiosis. Perhaps, proper supplementation should be considered to keep gut microbiota in large biodiversity and richness, especially under unfavorable gut conditions associated with intense exercise.

Trial registration

Prospero CRD42021264064.

Age-Related Hearing Loss: The Link between Inflammaging, Immunosenescence, and Gut Dysbiosis

This article provides a theoretical overview of the association between age-related hearing loss (ARHL), immune system ageing (immunosenescence), and chronic inflammation. ARHL, or presbyacusis, is the most common sensory disability that significantly reduces the quality of life and has a high economic impact. This disorder is linked to genetic risk factors but is also influenced by a lifelong cumulative effect of environmental stressors, such as noise, otological diseases, or ototoxic drugs. Age-related hearing loss and other age-related disorders share common mechanisms which often converge on low-grade chronic inflammation known as "inflammaging". Various stimuli can sustain inflammaging, including pathogens, cell debris, nutrients, and gut microbiota. As a result of ageing, the immune system can become defective, leading to the accumulation of unresolved inflammatory processes in the body. Gut microbiota plays a central role in inflammaging because it can release inflammatory mediators and crosstalk with other organ systems. A proinflammatory gut environment associated with ageing could result in a leaky gut and the translocation of bacterial metabolites and inflammatory mediators to distant organs via the systemic circulation. Here, we postulate that inflammaging, as a result of immunosenescence and gut dysbiosis, accelerates age-related cochlear degeneration, contributing to the development of ARHL. Age-dependent gut dysbiosis was included as a hypothetical link that should receive more attention in future studies.

A preliminary study on the diversity of butyrate-producing bacteria in response to the treatment of depression with Xiaoyaosan

Butyrate-producing bacteria generate butyrate, which has antidepressant effects. Xiaoyaosan (XYS), a traditional Chinese medicine (TCM) used to treat depression, may improve depression-like behaviour by modulating the gut microbiota. However, the functional groups and mechanisms of action in the XYS treatment of depression remain unknown. This study aimed to analyse with clone sequencing the changes in intestinal butyrate-producing bacteria in XYS-treated chronic unpredictable mild stress (CUMS) rats. We successfully established the XYS-treated CUMS rat model of depression. Rat faecal samples were collected before, during, and after the experiment, and butyryl-CoA:acetate CoA-transferase gene primers were selected for PCR amplification to determine the diversity of butyrate-producing bacteria. The results showed that XYS increased intestinal butyrate-producing bacterial diversity in CUMS rats regarding phylum and genus numbers; the number of phyla increased to two, distributed in Firmicutes and Bacteroides, and four genera were distributed in Eubacterium sp., Roseburia sp., Clostridium sp. and Bacteroides sp. Only one phylum and two genera were present in the model group without XYS treatment. Our findings indicate that XYS can improve depression-like behaviour by regulating intestinal butyrate-producing bacteria diversity, particularly Roseburia sp. and Eubacterium sp., thus providing new insights into the targeted regulation of the intestinal flora to treat depression.

Intestinal Microbiota-Derived Short Chain Fatty Acids in Host Health and Disease

Intestinal microbiota has its role as an important component of human physiology. It produces metabolites that module key functions to establish a symbiotic crosstalk with their host. Among them, short chain fatty acids (SCFAs), produced by intestinal bacteria during the fermentation of partially and non-digestible polysaccharides, play key roles in regulating colon physiology and changing intestinal environment. Recent research has found that SCFAs not only influence the signal transduction pathway in the gut, but they also reach tissues and organs outside of the gut, through their circulation in the blood. Growing evidence highlights the importance of SCFAs level in influencing health maintenance and disease development. SCFAs are probably involved in the management of host health in a complicated (positive or negative) way. Here, we review the current understanding of SCFAs effects on host physiology and discuss the potential prevention and therapeutics of SCFAs in a variety of disorders. It provides a systematic theoretical basis for the study of mechanisms and precise intake level of SCFAs to promote human health.

Dietary Fiber as a Counterbalance to Age-Related Microglial Cell Dysfunction

With increasing age, microglia shift toward a pro-inflammatory phenotype that may predispose individuals to neurodegenerative disease. Because fiber fermentation in the colon produces bioactive short-chain fatty acids (SCFAs; e.g., acetate, butyrate, and propionate) that signal through the gut-brain axis, increasing dietary fiber may prevent or reverse age-related dysregulation of microglia. Adult (3–4 months old) and aged (23–24 months old) male and female mice were given ad libitum access to a modified AIN-93M diet with 1% cellulose or the same diet with 2.5 or 5.0% inulin for 8 weeks. Several adult and aged male mice fed 0 or 5% inulin were randomly selected for whole brain single-cell RNA sequencing (scRNA-seq) and differential gene expression analysis to classify brain microglia according to gene expression profile; and identify additional genetic markers of aging as possible targets for dietary interventions. Microglia were isolated from remaining mice and expression of selected aging-, inflammatory-, and sensome-related genes was assessed by Fluidigm as was the ex vivo secretion of tumor necrosis factor-alpha (TNF-α). SCFAs were measured in samples collected from the cecum. Microglia from adult and aged mice segregated into distinct phenotypes according to their gene expression profile. In aged mice, a considerably greater proportion of the population of microglia was identified being “activated” and a considerably smaller proportion was identified being “quiescent.” These findings using whole brain scRNA-seq were largely corroborated using highly purified microglia and Fluidigm analysis to assess a selected panel of genes. Aged mice compared to adults had lower levels of SCFA’s in cecum. Dietary inulin increased SCFAs in cecum and mostly restored microglial cell gene expression and TNF-α secretion to that seen in adults. Sex differences were observed with females having lower levels of SCFAs in cecum and increased neuroinflammation. Overall, these data support the use of fiber supplementation as a strategy to counterbalance the age-related microglial dysregulation.

Biochemical and Metabolical Pathways Associated with Microbiota-Derived Butyrate in Colorectal Cancer and Omega-3 Fatty Acids Implications: A Narrative Review

Knowledge regarding the influence of the microbial community in cancer promotion or protection has expanded even more through the study of bacterial metabolic products and how they can modulate cancer risk, which represents an extremely challenging approach for the relationship between intestinal microbiota and colorectal cancer (CRC). This review discusses research progress on the effect of bacterial dysbiosis from a metabolic point of view, particularly on the biochemical mechanisms of butyrate, one of the main short chain fatty acids (SCFAs) with anti-inflammatory and anti-tumor properties in CRC. Increased daily intake of omega-3 polyunsaturated fatty acids (PUFAs) significantly increases the density of bacteria that are known to produce butyrate. Omega-3 PUFAs have been proposed as a treatment to prevent gut microbiota dysregulation and lower the risk or progression of CRC.

Rebalancing the unbalanced aged immune system - A special focus on zinc

Nowadays, aging is understood as a dynamic and multifaceted dysregulation process that spares almost no human organ or cell. The immune system being among the most affected, it has been shown predominantly that its integrity determines the tightrope walk between the difference of escaping or suffering from age-related diseases. Next to drug-based anti-aging strategies, micronutrient intervention may represent an emerging but less radical way to slow immune aging. While a sufficient supply of a variety of micronutrients is undeniably important, adequate intake of the trace element zinc appears to tower over others in terms of reaching old age. Inconveniently, zinc deficiency prevalence among the elderly is high, which in turn contributes to increased susceptibility to infection, decreased anti-tumor immunity as well as attenuated response to vaccination. Driven by this research, this review aims to provide a comprehensive and up-to-date overview of the various rebalancing capabilities of zinc in the unbalanced immune system of the elderly. This includes an in-depth and cell type-centered discussion on the role of zinc in immunosenescence and inflammaging. We further address upcoming translational aspects e.g. how zinc deficiency promotes the flourishing of certain pathogenic taxa of the gut microbiome and how zinc supply counteracts such alterations in a manner that may contribute to longevity. In the light of the ongoing COVID-19 pandemic, we also briefly review current knowledge on the interdependency between age, zinc status, and respiratory infections. Based on two concrete examples and considering the latest findings in the field we conclude our remarks by outlining tremendous parallels between suboptimal zinc status and accelerated aging on the one hand and an optimized zinc status and successful aging on the other hand.

Impact of healthy aging on active bacterial assemblages throughout the gastrointestinal tract

The adaption of gut microbiota (GM) throughout human life is a key factor in maintaining health. Interventions to restore a healthy GM composition may have the potential to improve health and disease outcomes in the elderly. We performed a comprehensive characterization of changes in the luminal and mucosa-associated microbiota composition in elderly compared with younger healthy individuals. Samples from saliva and feces, and biopsies from the upper and lower gastrointestinal tract (UGIT, LGIT), were collected from 59 asymptomatic individuals grouped by age: 40-55, 56-70, and 71-85 years). All underwent anthropometric, geriatric, and nutritional assessment. RNA was extracted and reverse-transcribed into complementary DNA; the V1-V2 regions of 16S ribosomal RNA genes were amplified and sequenced. Abundances of the taxa in all taxonomic ranks in each sample type were used to construct sample-similarity matrices by the Bray-Curtis algorithm. Significant differences between defined groups were assessed by analysis of similarity. The bacterial community showed strong interindividual variations and a clear distinction between samples from UGIT, LGIT, and feces. While in saliva some taxa were affected by aging, this number was considerably greater in UGIT and was subsequently higher in LGIT. Unexpectedly, aging scarcely influenced the bacterial community of feces over the age range of 40-85 years. The development of interventions to preserve and restore human health with increased age by establishing a healthy gut microbiome should not rely solely on data from fecal analysis, as the intestinal mucosa is affected by more significant changes, which differ from those observed in fecal analyses.

Differential effects of early-life and post-weaning galactooligosaccharides intervention on colonic bacterial composition and function in weaning piglets

Recently, we have proved that the early-life galactooligosaccharides (GOS) intervention could improve the colonic function by altering the bacterial composition in the suckling piglets. However, whether the early-life GOS (ELG) intervention could have a long influence of the colonic microbiota, and the ELG and post-weaning GOS (PWG) combined intervention would have an interaction effect on maintaining colonic health in weaning piglets remain to be explored. Thus in this study, we illustrated the differential effect of ELG and PWG intervention on colonic microbiota and colonic function of weaning piglets. Our results showed that both the ELG and PWG intervention decreased the diarrhea frequency of weaning piglets, while the PWG intervention increased colonic indexes. After 16S rRNA MiSeq sequencing of gut bacteria belonged to colonic niches (mucosa and digesta), the PWG increased the α-diversity of colonic mucosal bacteria was revealed. In addition, we found both the ELG and PWG intervention enriched the abundance of short chain fatty acids (SCFAs) producer in different colonic niches and increased total SCFAs concentrations in colonic digesta. These changes selectively modulated the mRNA expression of pattern recognition receptors and barrier proteins in the colonic mucosa. Of note, the combined effect of ELG and PWG effectively enhanced colonic SCFAs producer enrichment and up-regulated the butyrate concentration. Meanwhile, the gene expression of MyD88-NFκB signaling and the pro-inflammatory cytokines contents were markedly reduced under the combined effect of ELG and PWG. Importance Reducing the disorders of gut ecosystem is an effective way to relieve weaning stresses of piglets and save economic losses in the modern swine industry. To this end, prebiotics were often added in diet during the weaning transition. In present study, we demonstrated that the ELG and PWG intervention had shown different effects on the bacterial composition of different colonic niches and colonic function in the weaning piglets. Especially under the combined effect of ELG and PWG intervention, the gene expression of MyD88-NFκB signaling and the contents of pro-inflammation cytokines decreased with the increasing concentration of butyrate, which is one of the important microbial metabolites in the colon of weaning piglets. These findings further provided new insights into nutritional interventions to alleviate intestinal ecosystem dysbiosis and gut dysfunction in the piglets during the weaning transition.

Short-chain fatty acids as modulators of redox signaling in health and disease

Short-chain fatty acids (SCFAs), produced by colonic bacteria and obtained from the diet, have been linked to beneficial effects on human health associated with their metabolic and signaling properties. Their physiological functions are related to their aliphatic tail length and dependent on the activation of specific membrane receptors. In this review, we focus on the mechanisms underlying SCFAs mediated protection against oxidative and mitochondrial stress and their role in regulating metabolic pathways in specific tissues. We critically evaluate the evidence for their cytoprotective roles in suppressing inflammation and carcinogenesis and the consequences of aging. The ability of these natural compounds to induce signaling pathways, involving nuclear erythroid 2-related factor 2 (Nrf2), contributes to the maintenance of redox homeostasis under physiological conditions. SCFAs may thus serve as nutritional and therapeutic agents in healthy aging and in vascular and other diseases such as diabetes, neuropathologies and cancer.

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SCFAs are a link between the microbiota, redox signaling and host metabolism.

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SCFAs modulate Nrf2 redox signaling through specific free fatty acid receptors.

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Butyrate induces epigenetic regulation and/or Nrf2 nuclear translocation.

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Butyrate and propionate protect the blood-brain barrier by facilitating docosahexaenoic acid transport.

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Regulation of redox homeostasis by SCFAs supports their potential as therapeutic nutrients in health and disease.

Aging, Frailty, and the Microbiome-How Dysbiosis Influences Human Aging and Disease

The human gut microbiome is a collection of bacteria, protozoa, fungi, and viruses that coexist in our bodies and are essential in protective, metabolic, and physiologic functions of human health. Gut dysbiosis has traditionally been linked to increased risk of infection, but imbalances within the intestinal microbial community structure that correlate with untoward inflammatory responses are increasingly recognized as being involved in disease processes that affect many organ systems in the body. Furthermore, it is becoming more apparent that the connection between gut dysbiosis and age-related diseases may lie in how the gut microbiome communicates with both the intestinal mucosa and the systemic immune system, given that these networks have a common interconnection to frailty. We therefore discuss recent advances in our understanding of the important role the microbiome plays in aging and how this knowledge opens the door for potential novel therapeutics aimed at shaping a less dysbiotic microbiome to prevent or treat age-related diseases.

A polyphenol-rich dietary pattern improves intestinal permeability, evaluated as serum zonulin levels, in older subjects: The MaPLE randomised controlled trial

BACKGROUND & AIM

Increased intestinal permeability (IP) can occur in older people and contribute to the activation of the immune system and inflammation. Dietary interventions may represent a potential strategy to reduce IP. In this regard, specific food bioactives such as polyphenols have been proposed as potential IP modulator due to their ability to affect several critical targets and pathways that control IP. The trial aimed to test the hypothesis that a polyphenol-rich dietary pattern can decrease serum zonulin levels, an IP surrogate marker involved in tight junction modulation, and can beneficially alter the intestinal microbiota, and IP-associated biochemical and clinical markers in older subjects.

METHODS

A randomised, controlled, cross-over intervention trial was performed. Sixty-six subjects (aged ≥ 60 y) with increased IP based on serum zonulin levels, were randomly allocated to one of the two arms of the intervention consisting of a control diet (C-diet) vs. a polyphenol-rich diet (PR-diet). Each intervention was 8-week long and separated by an 8-week wash out period. At the beginning and at the end of each intervention period, serum samples were collected for the quantification of zonulin and other biological markers. Faecal samples were also collected to investigate the intestinal microbial ecosystem. In addition, anthropometrical/physical/biochemical parameters and food intake were evaluated.

RESULTS

Fifty-one subjects successfully completed the intervention and a high compliance to the dietary protocols was demonstrated. Overall, polyphenol intake significantly increased from a mean of 812 mg/day in the C diet to 1391 mg/day in the PR-diet. Two-way analysis of variance showed a significant effect of treatment (p = 0.008) and treatment × time interaction (p = 0.025) on serum zonulin levels, which decreased after the 8-week PR-diet. In addition, a treatment × time interaction was observed showing a reduction of diastolic blood pressure (p = 0.028) following the PR-diet, which was strongest in those not using antihypertensive drugs. A decrease in both diastolic (p = 0.043) and systolic blood pressure (p = 0.042) was observed in women. Interestingly, a significant increase in fibre-fermenting and butyrate-producing bacteria such as the family Ruminococcaceae and members of the genus Faecalibacterium was observed following the PR intervention. The efficacy of this dietary intervention was greater in subjects with higher serum zonulin at baseline, who showed more pronounced alterations in the markers under study. Furthermore, zonulin reduction was also stronger among subjects with higher body mass index and with insulin resistance at baseline, thus demonstrating the close interplay between IP and metabolic features.

CONCLUSIONS

These data show, for the first time, that a PR-diet can reduce serum zonulin levels, an indirect marker of IP. In addition, PR-diet reduced blood pressure and increased fibre-fermenting and butyrate-producing bacteria. These findings may represent an initial breakthrough for further intervention studies evaluating possible dietary treatments for the management of IP, inflammation and gut function in different target populations. THIS STUDY WAS REGISTERED AT WWW.ISRCTN.

ORG AS

ISRCTN10214981.

The Gut Microbiome, Aging, and Longevity: A Systematic Review

Aging is determined by complex interactions among genetic and environmental factors. Increasing evidence suggests that the gut microbiome lies at the core of many age-associated changes, including immune system dysregulation and susceptibility to diseases. The gut microbiota undergoes extensive changes across the lifespan, and age-related processes may influence the gut microbiota and its related metabolic alterations. The aim of this systematic review was to summarize the current literature on aging-associated alterations in diversity, composition, and functional features of the gut microbiota. We identified 27 empirical human studies of normal and successful aging suitable for inclusion. Alpha diversity of microbial taxa, functional pathways, and metabolites was higher in older adults, particularly among the oldest-old adults, compared to younger individuals. Beta diversity distances significantly differed across various developmental stages and were different even between oldest-old and younger-old adults. Differences in taxonomic composition and functional potential varied across studies, but Akkermansia was most consistently reported to be relatively more abundant with aging, whereas Faecalibacterium, Bacteroidaceae, and Lachnospiraceae were relatively reduced. Older adults have reduced pathways related to carbohydrate metabolism and amino acid synthesis; however, oldest-old adults exhibited functional differences that distinguished their microbiota from that of young-old adults, such as greater potential for short-chain fatty acid production and increased butyrate derivatives. Although a definitive interpretation is limited by the cross-sectional design of published reports, we integrated findings of microbial composition and downstream functional pathways and metabolites, offering possible explanations regarding age-related processes.

Microbiomes other than the gut: inflammaging and age-related diseases

During the course of evolution, bacteria have developed an intimate relationship with humans colonizing specific body sites at the interface with the body exterior and invaginations such as nose, mouth, lung, gut, vagina, genito-urinary tract, and skin and thus constituting an integrated meta-organism. The final result has been a mutual adaptation and functional integration which confers significant advantages to humans and bacteria. The immune system of the host co-evolved with the microbiota to develop complex mechanisms to recognize and destroy invading microbes, while preserving its own bacteria. Composition and diversity of the microbiota change according to development and aging and contribute to humans' health and fitness by modulating the immune system response and inflammaging and vice versa. In the last decades, we experienced an explosion of studies on the role of gut microbiota in aging, age-related diseases, and longevity; however, less reports are present on the role of the microbiota at different body sites. In this review, we describe the key steps of the co-evolution between Homo sapiens and microbiome and how this adaptation can impact on immunosenescence and inflammaging. We briefly summarized the role of gut microbiota in aging and longevity while bringing out the involvement of the other microbiota.

The Production of Listeriolysin O and Subsequent Intracellular Infections by Listeria monocytogenes Are Regulated by Exogenous Short Chain Fatty Acid Mixtures

Listeria monocytogenes is a foodborne pathogen capable of secreting listeriolysin O (LLO), a pore-forming toxin encoded by the hly gene. While the functions of LLO have been studied extensively, how the production of LLO is modulated by the intestinal environment, devoid of oxygen and enriched in short chain fatty acids (SCFAs), is not completely understood. Using L. monocytogenes strain 10403s, we found that hly transcription was moderately decreased by aerobic SCFA exposures but significantly increased by anaerobic SCFA exposures. Moreover, aerobic, but not anaerobic, exposure to low levels of SCFAs resulted in a significantly higher LLO activity. These results demonstrated that transcriptional and post-transcriptional regulations of LLO production were separately modulated by SCFAs and were responsive to oxygen levels. Examining isogenic mutants revealed that PrfA and SigB play a role in regulating LLO production in response to SCFAs. Effects of SCFAs were also present in the cardiotropic strain 07PF0776 but distinctly different from those in strain 10403s. For both strains, prior exposures to SCFAs altered intracellular infections in Caco-2 and RAW264.7 cells and the plaque sizes in L fibroblasts, a result confirming the ability of L. monocytogenes to adapt to SCFAs in ways that impact its subsequent infection outcomes.

Gut Microbial Protein Expression in Response to Dietary Patterns in a Controlled Feeding Study: A Metaproteomic Approach

Although the gut microbiome has been associated with dietary patterns linked to health, microbial metabolism is not well characterized. This ancillary study was a proof of principle analysis for a novel application of metaproteomics to study microbial protein expression in a controlled dietary intervention. We measured the response of the microbiome to diet in a randomized crossover dietary intervention of a whole-grain, low glycemic load diet (WG) and a refined-grain, high glycemic load diet (RG). Total proteins in stools from 9 participants at the end of each diet period (n = 18) were analyzed by LC MS/MS and proteins were identified using the Human Microbiome Project (HMP) human gut microbiome database and UniProt human protein databases. T-tests, controlling for false discovery rate (FDR) <10%, were used to compare the Gene Ontology (GO) biological processes and bacterial enzymes between the two interventions. Using shotgun proteomics, more than 53,000 unique peptides were identified including microbial (89%) and human peptides (11%). Forty-eight bacterial enzymes were statistically different between the diets, including those implicated in SCFA production and degradation of fatty acids. Enzymes associated with degradation of human mucin were significantly enriched in the RG diet. These results illustrate that the metaproteomic approach is a valuable tool to study the microbial metabolism of diets that may influence host health.

What is the collective effect of aging and HIV on the gut microbiome?

PURPOSE OF REVIEW

Aging and HIV share features of intestinal damage and alterations in the communities of enteric bacteria, termed dysbiosis. The purpose of this review is to highlight the various features of the gut microbiome in aging and in people with HIV (PWH) and to discuss how aging and HIV converge to impact the gut microbiome. The term microbiome reflects the combined genetic material of micro-organisms present including bacteria, viruses, bacteriophages, and fungi. To date, the majority of studies investigating the impact of aging and HIV on the gut microbiome have focused on bacteria, and therefore, for the purposes of this review, the term 'microbiome' is used to reflect enteric bacterial communities.

RECENT FINDINGS

Aging is associated with alterations in the gut bacterial microbiome. Although changes vary by the age of the population, lifestyle (diet, physical activity) and geographic location, the age-associated dysbiosis is typically characterized by an increase in facultative anaerobes with inflammatory properties and a decrease in obligate anaerobes that play critical roles in maintaining intestinal homeostasis and in regulating host immunity. PWH also have dysbiotic gut microbiomes, many features of which reflect those observed in elderly persons. In one study, the age effect on the gut microbiome differed based on HIV serostatus in older adults.

SUMMARY

HIV and age may interact to shape the gut microbiome. Future studies should investigate relationships between the gut microbiome and age-associated comorbidities in older PWH populations. Identifying these links will provide new avenues for treatments and interventions to improve the healthspan and lifespan of older PWH.

Diet and Gut Microbes Act Coordinately to Enhance Programmed Cell Death and Reduce Colorectal Cancer Risk

Diet is an important risk factor for colorectal cancer (CRC), and several dietary constituents implicated in CRC are modified by gut microbial metabolism. Microbial fermentation of dietary fiber produces short-chain fatty acids, e.g., acetate, propionate, and butyrate. Dietary fiber has been shown to reduce colon tumors in animal models, and, in vitro, butyrate influences cellular pathways important to cancer risk. Furthermore, work from our group suggests that the combined effects of butyrate and omega-3 polyunsaturated fatty acids (n-3 PUFA) may enhance the chemopreventive potential of these dietary constituents. We postulate that the relatively low intakes of n-3 PUFA and fiber in Western populations and the failure to address interactions between these dietary components may explain why chemoprotective effects of n-3 PUFA and fermentable fibers have not been detected consistently in prospective cohort studies. In this review, we summarize the evidence outlining the effects of n-3 long-chain PUFA and highly fermentable fiber with respect to alterations in critical pathways important to CRC prevention, particularly intrinsic mitochondrial-mediated programmed cell death resulting from the accumulation of lipid reactive oxygen species (ferroptosis), and epigenetic programming related to lipid catabolism and beta-oxidation-associated genes.

Untapped "-omics": the microbial metagenome, estrobolome, and their influence on the development of breast cancer and response to treatment

With the advent of next generation sequencing technologies, there is an increasingly complex understanding of the role of gastrointestinal and local breast microbial dysbiosis in breast cancer. In this review, we summarize the current understanding of the microbiome's role in breast carcinogenesis, discussing modifiable risk factors that may affect breast cancer risk by inducing dysbiosis as well as recent sequencing data illustrating breast cancer subtype-specific differences in local breast tissue microbiota. We outline how the 'estrobolome,' the aggregate of estrogen-metabolizing enteric bacterial genes, may affect the risk of developing postmenopausal estrogen receptor-positive breast cancer. We also discuss the microbiome's potent capacity for anticancer therapy activation and deactivation, an important attribute of the gastrointestinal microbiome that has yet to be harnessed clinically.

Sugar Beet Pectin Supplementation Did Not Alter Profiles of Fecal Microbiota and Exhaled Breath in Healthy Young Adults and Healthy Elderly

Aging is accompanied with increased frailty and comorbidities, which is potentially associated with microbiome perturbations. Dietary fibers could contribute to healthy aging by beneficially impacting gut microbiota and metabolite profiles. We aimed to compare young adults with elderly and investigate the effect of pectin supplementation on fecal microbiota composition, short chain fatty acids (SCFAs), and exhaled volatile organic compounds (VOCs) while using a randomized, double-blind, placebo-controlled parallel design. Fifty-two young adults and 48 elderly consumed 15 g/day sugar beet pectin or maltodextrin for four weeks. Fecal and exhaled breath samples were collected before and after the intervention period. Fecal samples were used for microbiota profiling by 16S rRNA gene amplicon sequencing, and for analysis of SCFAs by gas chromatography (GC). Breath was used for VOC analysis by GC-tof-MS. Young adults and elderly showed similar fecal SCFA and exhaled VOC profiles. Additionally, fecal microbiota profiles were similar, with five genera significantly different in relative abundance. Pectin supplementation did not significantly alter fecal microbiota, SCFA or exhaled VOC profiles in elderly or young adults. In conclusion, aside from some minor differences in microbial composition, healthy elderly and young adults showed comparable fecal microbiota composition and activity, which were not altered by pectin supplementation.

Integrative analysis of gut microbiota composition, host colonic gene expression and intraluminal metabolites in aging C57BL/6J mice

The aging process is associated with diminished colonic health. In this study, we applied an integrative approach to reveal potential interactions between determinants of colonic health in aging C57BL/6J mice. Analysis of gut microbiota composition revealed an enrichment of various potential pathobionts, including Desulfovibrio spp., and a decline of the health-promoting Akkermansia spp. and Lactobacillus spp. during aging. Intraluminal concentrations of various metabolites varied between ages and we found evidence for an increased gut permeability at higher age. Colonic gene expression analysis suggested that during the early phase of aging (between 6 and 12 months), expression of genes involved in epithelial-to-mesenchymal transition and (re)organization of the extracellular matrix were increased. Differential expression of these genes was strongly correlated with Bifidobacterium spp. During the later phase of aging (between 12 and 28 months), gene expression profiles pointed towards a diminished antimicrobial defense and were correlated with an uncultured Gastranaerophilales spp. This study demonstrates that aging is associated with pronounced changes in gut microbiota composition and colonic gene expression. Furthermore, the strong correlations between specific bacterial genera and host gene expression may imply that orchestrated interactions take place in the vicinity of the colonic wall and potentially mediate colonic health during aging.

Glycan utilisation system in Bacteroides and Bifidobacteria and their roles in gut stability and health

Gut residential hundred trillion microbial cells are indispensable for maintaining gut homeostasis and impact on host physiology, development and immune systems. Many of them have displayed excellence in utilising dietary- and host-derived complex glycans and are producing useful postbiotics including short-chain fatty acids to primarily fuel different organs of the host. Therefore, employing individual microbiota is nowadays becoming a propitious target in biomedical for improving gut dysbiosis conditions of the host. Among other gut microbial communities, Bacteroides and Bifidobacteria are coevolved to utilise diverse ranges of diet- and host-derived glycans through harmonising distinct glycan utilisation systems. These gut symbionts frequently share digested oligosaccharides, carbohydrate-active enzymes and fermentable intermediate molecules for sustaining gut microbial symbiosis and improving fitness of own or other communities. Genomics approaches have provided unprecedented insights into these functions, but their precise mechanisms of action have poorly known. Sympathetic glycan-utilising strategy of each gut commensal will provide overview of mechanistic dynamic nature of the gut environment and will then assist in applying aptly personalised nutritional therapy. Thus, the review critically summarises cutting edge understanding of major plant- and host-derived glycan-utilising systems of Bacteroides and Bifidobacteria. Their evolutionary adaptation to gut environment and roles of postbiotics in human health are also highlighted.

Age-Associated Changes in the Immune System and Blood⁻Brain Barrier Functions

Age is associated with altered immune functions that may affect the brain. Brain barriers, including the blood-brain barrier (BBB) and blood-CSF barrier (BCSFB), are important interfaces for neuroimmune communication, and are affected by aging. In this review, we explore novel mechanisms by which the aging immune system alters central nervous system functions and neuroimmune responses, with a focus on brain barriers. Specific emphasis will be on recent works that have identified novel mechanisms by which BBB/BCSFB functions change with age, interactions of the BBB with age-associated immune factors, and contributions of the BBB to age-associated neurological disorders. Understanding how age alters BBB functions and responses to pathological insults could provide important insight on the role of the BBB in the progression of cognitive decline and neurodegenerative disease.

Effects of dietary supplementation of the lignocelluloses FibreCell and OptiCell on performance, expression of inflammation-related genes and the gut microbiome of broilers

This study investigated the hypothesis that dietary supplementation of lignocellulose in broilers influences the gut bacterial population and bacterial fermentation, has anti-inflammatory effects, and increases mucin synthesis in the intestine, and, through these changes, influences broiler performance positively. Day-old male Cobb 500 broilers (n = 96) were allotted to 3 experimental groups and fed 3 different maize-wheat-soybean meal-based basal diets during days 1 to 10, 11 to 21, and 22 to 35. The basal diets were fed to the control group, and were supplemented with 0.8% of a standard lignocellulose (LCS) or a fermentable lignocellulose (LCF). Body weight and feed consumption were determined, and at slaughter (day 35), carcass and gizzard weights and gizzard content pH were recorded, and samples of jejunum, cecum, and colon mucosa and of cecum digesta were collected from 15 birds/group. Growth performance and feed intake were not influenced, but dressing percentage was higher in group LCF compared to the other groups. In group LCS and the control group, performance, gizzard weight and gizzard content pH, intestinal gene expression of pro-inflammatory cytokines and of the mucins 2, 5ac and 13, the cecal short-chain fatty acid (SCFA) profile, and bacterial diversity were similar, and relative abundance of bacterial groups (16S DNA sequencing) differed. Supplementation of LCF decreased the expression of the pro-inflammatory genes encoding interleukins 1ß and 17 (P < 0.05) and those of 2 and 8 (P < 0.10) in the jejunum only. The bacterial population differed, and the SCFA profile shifted toward acetate at the expense of butyrate in group LCF compared to the control group. For example, the abundance of Firmicutes and of Ruminococcaceae and Lactobacillaceae decreased, whereas those of Peptostreptococcaceae, Erysipelotrichaceae, and Enterobacteriaceae and that of members of the phylum Proteobacteria increased in group LCF compared to the control group. These data indicate that the susceptibility of lignocellulose to fermentation is crucial for mediating its effects on intestinal gene expression and the bacterial population in the cecum, which may also affect dressing percentage.

Among older adults, age-related changes in the stool microbiome differ by HIV-1 serostatus

Background

HIV-1 infection and physiological aging are independently linked to elevated systemic inflammation and changes in enteric microbial communities (dysbiosis). However, knowledge of the direct effect of HIV infection on the aging microbiome and potential links to systemic inflammation is lacking.

Methods

In a cross-sectional study of older people living with HIV (PLWH) (median age 61.5 years, N = 14) and uninfected controls (median 58 years, n = 22) we compared stool microbiota, levels of microbial metabolites (short-chain fatty acid levels, SCFA) and systemic inflammatory biomarkers by HIV serostatus and age.

Findings

HIV and age were independently associated with distinct changes in the stool microbiome. For example, abundances of Enterobacter and Paraprevotella were higher and Eggerthella and Roseburia lower among PLWH compared to uninfected controls. Age-related microbiome changes also differed by HIV serostatus. Some bacteria with inflammatory potential (e.g. Escherichia) increased with age among PLWH, but not controls. Stool SCFA levels were similar between the two groups yet patterns of associations between individual microbial taxa and SCFA levels differed. Abundance of various genera including Escherichia and Bifidobacterium positively associated with inflammatory biomarkers (e.g. soluble Tumor Necrosis Factor Receptors) among PLWH, but not among controls.

Interpretation

The age effect on the gut microbiome and associations between microbiota and microbial metabolites or systemic inflammation differed based on HIV serostatus, raising important implications for the impact of therapeutic interventions, dependent on HIV serostatus or age.

The Microbial Metabolite Butyrate Stimulates Bone Formation via T Regulatory Cell-Mediated Regulation of WNT10B Expression

Nutritional supplementation with probiotics can prevent pathologic bone loss. Here we examined the impact of supplementation with Lactobacillus rhamnosus GG (LGG) on bone homeostasis in eugonadic young mice. Micro-computed tomography revealed that LGG increased trabecular bone volume in mice, which was due to increased bone formation. Butyrate produced in the gut following LGG ingestion, or butyrate fed directly to germ-free mice, induced the expansion of intestinal and bone marrow (BM) regulatory T (Treg) cells. Interaction of BM CD8+ T cells with Treg cells resulted in increased secretion of Wnt10b, a bone anabolic Wnt ligand. Mechanistically, Treg cells promoted the assembly of a NFAT1-SMAD3 transcription complex in CD8+ cells, which drove expression of Wnt10b. Reducing Treg cell numbers, or reconstitution of TCRβ-/- mice with CD8+ T cells from Wnt10b-/- mice, prevented butyrate-induced bone formation and bone mass acquisition. Thus, butyrate concentrations regulate bone anabolism via Treg cell-mediated regulation of CD8+ T cell Wnt10b production.

Sulforaphane Normalizes Intestinal Flora and Enhances Gut Barrier in Mice with BBN-Induced Bladder Cancer

SCOPE

Gut microbiota imbalance, inflammation, and gut barrier deficiency play an important role in carcinogenesis. Sulforaphane (SFN), an isothiocyanate found in cruciferous vegetables, has been proven to be highly effective in inhibiting cancer. The objective of this study is to investigate the potential roles of the gut microbiota in the inhibition of BBN-induced bladder cancer by SFN.

METHODS AND RESULTS

N-butyl-N-(4-hydroxybutyl)-nitrosamine is used to induce bladder cancer in male C57BL/6 mice, with or without SFN for 23 weeks. SFN ameliorates the histological changes characteristic of bladder cancer, resulting in fewer submucosal capillaries. SFN normalizes gut microbiota dysbiosis in mice with BBN-induced bladder cancer with a significant increase in Bacteroides fragilis and Clostridium cluster I. SFN also increases butyric acid levels in the mouse colon, and repairs the injury to the mucosal epithelium of the colon and cecum through the upregulation of the expression of tight junction proteins and GLP2. SFN greatly decreases the release of cytokines (IL-6) and secretory immunoglobulin A in the mice with bladder cancer.

CONCLUSION

These results suggest that SFN protects against chemical-induced bladder cancer through normalizing the composition of gut microbiota and repairing the physiological destruction of the gut barrier, as well as decreasing inflammation and the immune response.

Butyrate and Dietary Soluble Fiber Improve Neuroinflammation Associated With Aging in Mice

Aging results in chronic systemic inflammation that can alter neuroinflammation of the brain. Specifically, microglia shift to a pro-inflammatory phenotype predisposing them to hyperactivation upon stimulation by peripheral immune signals. It is proposed that certain nutrients can delay brain aging by preventing or reversing microglial hyperactivation. Butyrate, a short-chain fatty acid (SCFA) produced primarily by bacterial fermentation of fiber in the colon, has been extensively studied pharmacologically as a histone deacetylase inhibitor and serves as an attractive therapeutic candidate, as butyrate has also been shown to be anti-inflammatory and improve memory in animal models. In this study, we demonstrate that butyrate can attenuate pro-inflammatory cytokine expression in microglia in aged mice. It is still not fully understood, however, if an increase in butyrate-producing bacteria in the gut as a consequence of a diet high in soluble fiber could affect microglial activation during aging. Adult and aged mice were fed either a 1% cellulose (low fiber) or 5% inulin (high fiber) diet for 4 weeks. Findings indicate that mice fed inulin had an altered gut microbiome and increased butyrate, acetate, and total SCFA production. In addition, histological scoring of the distal colon demonstrated that aged animals on the low fiber diet had increased inflammatory infiltrate that was significantly reduced in animals consuming the high fiber diet. Furthermore, gene expression of inflammatory markers, epigenetic regulators, and the microglial sensory apparatus (i.e., the sensome) were altered by both diet and age, with aged animals exhibiting a more anti-inflammatory microglial profile on the high fiber diet. Taken together, high fiber supplementation in aging is a non-invasive strategy to increase butyrate levels, and these data suggest that an increase in butyrate through added soluble fiber such as inulin could counterbalance the age-related microbiota dysbiosis, potentially leading to neurological benefits.

Origination, change, and modulation of geriatric disease-related gut microbiota during life

The age-related changes in the diversity and composition of the gut microbiota are well described in recent studies. These changes have been suggested to be influenced by age-associated weakening of the immune system and low-grade chronic inflammation, resulting in numerous age-associated pathological conditions. Gut microbiota homeostasis is important throughout the life of the host by providing vital functions to regulate various immunological functions and homeostasis. Based on published results, we summarize the relationship between the gut microbiota and aging-related diseases, especially Parkinson's disease, immunosenescence, rheumatoid arthritis, bone loss, and metabolic syndrome. The change in composition of the gut microbiota and gut ecosystem during life and its influence on the host immunologic and metabolic phenotype are also analyzed to determine factors that affect aging-related diseases. Approaches to maintain host health and prevent or cure geriatric diseases are also discussed.

HIV and aging: role of the microbiome

PURPOSE OF REVIEW

The purpose of this article is to review age-associated alterations in microbiota composition, diversity and functional features in context of immune senescence, chronic inflammation and comorbidities associated with HIV infection. The overall goal is to assess whether modulating the microbiome will likely improve resilience of the immune system and augment return to health.

RECENT FINDINGS

Alteration in the gut microbiota composition diversity and function occur in HIV and aging. Importantly, butyrate producing bacteria are reduced in both HIV and aging individuals. There is increasing relevance of studying metabolomics in the context of HIV-associated non-AIDS comorbidities and aging. Interventional prospects of probiotics, prebiotics and fecal microbiota transplantation in HIV and aging will provide novel therapeutic approaches.

SUMMARY

Increasing evidence suggests a significant link in changes in the composition, diversity and functional aspects of intestinal microbiome with normal aging and HIV infection. Data on association of metabolites produced by the microbiome with HIV-associated non-AIDS comorbidities is mounting. The impact of the microbiome alterations on inflammation, immune and organ senescence and mechanisms by which bio-behavioral pathways will exacerbate these outcomes needs to be further evaluated.

Bacteria in the ageing gut: did the taming of fire promote a long human lifespan?

Unique among animals as they evolved towards Homo sapiens, hominins progressively cooked their food on a routine basis. Cooked products are characterized by singular chemical compounds, derived from the pervasive Maillard reaction. This same reaction is omnipresent in normal metabolism involving carbonyls and amines, and its products accumulate with age. The gut microbiota acts as a first line of defence against the toxicity of cooked Maillard compounds, that also selectively shape the microbial flora, letting specific metabolites to reach the blood stream. Positive selection of metabolic functions allowed the body of hominins who tamed fire to use and dispose of these age-related compounds. I propose here that, as a hopeful accidental consequence, this resulted in extending human lifespan far beyond that of our great ape cousins. The limited data exploring the role of taming fire on the human genetic setup and on its microbiota is discussed in relation with ageing.

Exercise Alters Gut Microbiota Composition and Function in Lean and Obese Humans

PURPOSE

Exercise is associated with altered gut microbial composition, but studies have not investigated whether the gut microbiota and associated metabolites are modulated by exercise training in humans. We explored the impact of 6 wk of endurance exercise on the composition, functional capacity, and metabolic output of the gut microbiota in lean and obese adults with multiple-day dietary controls before outcome variable collection.

METHODS

Thirty-two lean (n = 18 [9 female]) and obese (n = 14 [11 female]), previously sedentary subjects participated in 6 wk of supervised, endurance-based exercise training (3 d·wk) that progressed from 30 to 60 min·d and from moderate (60% of HR reserve) to vigorous intensity (75% HR reserve). Subsequently, participants returned to a sedentary lifestyle activity for a 6-wk washout period. Fecal samples were collected before and after 6 wk of exercise, as well as after the sedentary washout period, with 3-d dietary controls in place before each collection.

RESULTS

β-diversity analysis revealed that exercise-induced alterations of the gut microbiota were dependent on obesity status. Exercise increased fecal concentrations of short-chain fatty acids in lean, but not obese, participants. Exercise-induced shifts in metabolic output of the microbiota paralleled changes in bacterial genes and taxa capable of short-chain fatty acid production. Lastly, exercise-induced changes in the microbiota were largely reversed once exercise training ceased.

CONCLUSION

These findings suggest that exercise training induces compositional and functional changes in the human gut microbiota that are dependent on obesity status, independent of diet and contingent on the sustainment of exercise.

Effect of Vegan Fecal Microbiota Transplantation on Carnitine- and Choline-Derived Trimethylamine-N-Oxide Production and Vascular Inflammation in Patients With Metabolic Syndrome

BACKGROUND

Intestinal microbiota have been found to be linked to cardiovascular disease via conversion of the dietary compounds choline and carnitine to the atherogenic metabolite TMAO (trimethylamine-N-oxide). Specifically, a vegan diet was associated with decreased plasma TMAO levels and nearly absent TMAO production on carnitine challenge.

METHODS AND RESULTS

We performed a double-blind randomized controlled pilot study in which 20 male metabolic syndrome patients were randomized to single lean vegan-donor or autologous fecal microbiota transplantation. At baseline and 2 weeks thereafter, we determined the ability to produce TMAO from d6-choline and d3-carnitine (eg, labeled and unlabeled TMAO in plasma and 24-hour urine after oral ingestion of 250 mg of both isotope-labeled precursor nutrients), and fecal samples were collected for analysis of microbiota composition. 18F-fluorodeoxyglucose positron emission tomography/computed tomography scans of the abdominal aorta, as well as ex vivo peripheral blood mononuclear cell cytokine production assays, were performed. At baseline, fecal microbiota composition differed significantly between vegans and metabolic syndrome patients. With vegan-donor fecal microbiota transplantation, intestinal microbiota composition in metabolic syndrome patients, as monitored by global fecal microbial community structure, changed toward a vegan profile in some of the patients; however, no functional effects from vegan-donor fecal microbiota transplantation were seen on TMAO production, abdominal aortic 18F-fluorodeoxyglucose uptake, or ex vivo cytokine production from peripheral blood mononuclear cells.

CONCLUSIONS

Single lean vegan-donor fecal microbiota transplantation in metabolic syndrome patients resulted in detectable changes in intestinal microbiota composition but failed to elicit changes in TMAO production capacity or parameters related to vascular inflammation.

CLINICAL TRIAL REGISTRATION

URL: http://www.trialregister.nl. Unique identifier: NTR 4338.

Simulated Digestion and Fermentation in Vitro by Human Gut Microbiota of Polysaccharides from Bee Collected Pollen of Chinese Wolfberry

Digestion and fermentation in vitro of polysaccharides from bee collected pollen of Chinese wolfberry (WBPPS) were investigated in the present study. It was found that WBPPS mainly consisted of mannose, ribose, rhamnose, galacturonic acid, glucose, galactose, xylose, and arabinose in a molar ratio of 0.38:0.09:0.17:0.64:0.22:0.67:0.08:1.03, respectively. WBPPS was not affected by human saliva. The fraction A (molecular weight 1340 kDa) of WBPPS was not broken down in simulated gastric and small intestinal juices, while the small fraction B (molecular weight 523 kDa) of WBPPS was degraded. Moreover, fermentation in vitro revealed that WBPPS could significantly enhance the production of short-chain fatty acids and modulate gut microbiota composition via increasing the relative abundances of genera Prevotella, Dialister, Megamonas, Faecalibacterium, and Alloprevotella and decreasing the numbers of genera Bacteroides, Clostridium XlVa, Parabacteroides, Escherichia/Shigella, Phascolarctobacterium, Parasutterella, Clostridium sensu stricto, and Fusobacterium.

Diet, Microbiota, and Metabolic Health: Trade-Off Between Saccharolytic and Proteolytic Fermentation

The intestinal microbiota have emerged as a central regulator of host metabolism and immune function, mediating the effects of diet on host health. However, the large diversity and individuality of the gut microbiota have made it difficult to draw conclusions about microbiota responses to dietary interventions. In the light of recent research, certain general patterns are emerging, revealing how the ecology of the gut microbiota profoundly depends on the quality and quantity of dietary carbohydrates and proteins. In this review, I provide an overview of the dependence of microbial ecology in the human colon on diet and how the effects of diet on host health depend partially on the microbiota. Understanding how the individual-specific microbiota respond to short- and long-term dietary changes and how they influence host energy homeostasis will enable targeted interventions to achieve specific outcomes, such as weight loss in obesity or weight gain in malnutrition.

Bacterial Diversity in Traditional Doogh in Comparison to Industrial Doogh

Forty-four samples of traditional Doogh and yoghurt were collected from 13 regions of 4 provinces in west of Iran (13 area) and analyzed using molecular methods including PCR, denaturing gradient gel electrophoresis (DGGE) of 16S rDNA, and sequencing. Moreover, collected samples as well as samples from industrially Doogh were analyzed with quantitative real-time PCR (RT-PCR). Analyzed 16S rRNA gene sequences of Doogh samples could be allocated to the presence of Lactobacillus spp. The typical yoghurt starter culture bacteria included four different Lactobacillus species with possible probiotic properties, L. acidophilus, L. helveticus, L. kefiranofaciens, and L. amylovorus. DGGE of traditional Doogh and yoghurt and RT-PCR of traditional Doogh and yoghurt and also industrial Doogh samples demonstrated that traditional Doogh and yoghurt show a higher abundance of total bacteria and lactobacilli and a higher bacterial diversity, respectively. Considering diversity and higher probiotic bacteria content in traditional Doogh, consumers’ healthiness in tribes and villages could be promoted with these indigenous products.

EGCG Prevents High Fat Diet-Induced Changes in Gut Microbiota, Decreases of DNA Strand Breaks, and Changes in Expression and DNA Methylation of Dnmt1 and MLH1 in C57BL/6J Male Mice

Obesity as a multifactorial disorder involves low-grade inflammation, increased reactive oxygen species incidence, gut microbiota aberrations, and epigenetic consequences. Thus, prevention and therapies with epigenetic active antioxidants, (-)-Epigallocatechin-3-gallate (EGCG), are of increasing interest. DNA damage, DNA methylation and gene expression of DNA methyltransferase 1, interleukin 6, and MutL homologue 1 were analyzed in C57BL/6J male mice fed a high-fat diet (HFD) or a control diet (CD) with and without EGCG supplementation. Gut microbiota was analyzed with quantitative real-time polymerase chain reaction. An induction of DNA damage was observed, as a consequence of HFD-feeding, whereas EGCG supplementation decreased DNA damage. HFD-feeding induced a higher inflammatory status. Supplementation reversed these effects, resulting in tissue specific gene expression and methylation patterns of DNA methyltransferase 1 and MutL homologue 1. HFD feeding caused a significant lower bacterial abundance. The Firmicutes/Bacteroidetes ratio is significantly lower in HFD + EGCG but higher in CD + EGCG compared to control groups. The results demonstrate the impact of EGCG on the one hand on gut microbiota which together with dietary components affects host health. On the other hand effects may derive from antioxidative activities as well as epigenetic modifications observed on CpG methylation but also likely to include other epigenetic elements.

Altered intestinal microbiota-host mitochondria crosstalk in new onset Crohn's disease

Intestinal microbial dysbiosis is associated with Crohn's disease (CD). However, the mechanisms leading to the chronic mucosal inflammation that characterizes this disease remain unclear. In this report, we use systems-level approaches to study the interactions between the gut microbiota and host in new-onset paediatric patients to evaluate causality and mechanisms of disease. We report an altered host proteome in CD patients indicative of impaired mitochondrial functions. In particular, mitochondrial proteins implicated in H₂S detoxification are downregulated, while the relative abundance of H₂S microbial producers is increased. Network correlation analysis reveals that Atopobium parvulum controls the central hub of H₂S producers. A. parvulum induces pancolitis in colitis-susceptible interleukin-10-deficient mice and this phenotype requires the presence of the intestinal microbiota. Administrating the H₂S scavenger bismuth mitigates A. parvulum-induced colitis in vivo. This study reveals that host–microbiota interactions are disturbed in CD and thus provides mechanistic insights into CD pathogenesis.

Crohn's disease is associated with altered intestinal microbiota. Here, the authors show that the microbe Atopobium parvulum is associated with Crohn's disease patients, triggers colitis in a mouse model, and that scavenging microbe-induced hydrogen sulfide improved symptoms in mice.