The gut microflora and its variety of roles in health and disease

Prevention effect of total ginsenosides and ginseng extract from Panax ginseng on cyclophosphamide-induced immunosuppression in mice

Oral decoction is widely applied in traditional Chinese medicines. The polysaccharides of decoction promote the exposure of small molecules and increase their bioavailability. This study mainly compared the component and activities of total ginsenosides (TGS) and ginseng extract (GE) on immunosuppressed mice induced by cyclophosphamide. Thirty-two mice were randomly divided into control, model, TGS, and GE groups. The mice were orally administered for 28 days and then injected with cyclophosphamide on the last four days. The results of component analysis showed the total content of 12 ginsenosides in TGS (67.21%) was higher than GE (2.04%); the total content of 17 amino acids in TGS (1.41%) was lower than GE (5.36%); the total content of 10 monosaccharides was similar in TGS (74.12%) and GE (76.36%). The animal results showed that both TGS and GE protected the hematopoietic function of bone marrow by inhibiting cell apoptosis, and recovering the normal cell cycle of BM; maintained the dynamic balance between the Th1 and Th2 cells; also protected the spleen, thymus, and liver. Meanwhile, TGS and GE protected the intestinal bacteria of immunosuppressed mice by increasing the abundance of lactobacillus and decreasing the abundance of the odoribacter and clostridia_UCG-014. The prevention effect of GE was superior to TGS in some parameters. In conclusion, TGS and GE protected the immune function of immunosuppressed mice induced by cyclophosphamide. Meanwhile, GE showed higher bioavailability and bioactivity compared with TGS, because the synergistic effect of polysaccharides and ginsenosides plays an important role in protecting the immune function.

The nanocomposites of modified attapulgite with vitamin E and mannan oligosaccharide regulated the intestinal epithelial barrier and improved intestinal microbiota composition to prevent diarrhea in weaned piglets

BACKGROUND

Overuse of antibiotics contributes to bacterial resistance in animals. Therefore, it is necessary to find a new way to ensure animal health and promote animal growth. This experiment was conducted to investigate the effect of mannan oligosaccharide (MOS)/vitamin E (VE)/attapulgite (APT) nanocomposites (SLK1, SLK3, SLK5) on growth performance and intestinal health in weaned piglets. Each 1 kg of SLK1, SLK3 or SLK5 contains 50 g of vitamin E, and each had a different MOS concentration [SLK1 (50 g kg ^-1 MOS), SLK3 (100 g kg ^-1 MOS), SLK5 (150 g kg ^-1 MOS)]. In total, 135 piglets were randomly divided into five groups (normal control group, traditional antibiotic substitutes group, SLK1 group, SLK3 group and SLK5 group), and growth performance, diarrhea index, intestinal epithelial barrier function and intestinal microbial composition were measured.

RESULTS

SLK1 and SLK5 significantly decreased diarrhea frequency in weaned piglets (p < 0.05). Furthermore, SLK5 significantly increased survival rate of weaned piglets compared to the traditional antibiotic substitutes group (p < 0.05). SLK5 also increased villus height of ileum, and increased goblet number of the jejunum (p < 0.05). 16S rRNA sequencing showed that SLK5 significantly regulated intestinal colonic microbiota composition (p < 0.05). Specifically, SLK5 significantly increased the abundance of Phascolarctobacterium succinatutens in the cecum and increased the abundance of Lactobacillus and Bifidobacterium in the colon (p < 0.05). In addition, dietary supplementation with 1 kg T^-1 SLK5 also significantly increased the propionate content in the colon, which is significantly correlated with Phascolarctobacterium (p < 0.05).

CONCLUSION

Dietary supplementation with 1 kg T^-1 SLK5 improved intestinal epithelial barrier function, and regulated intestinal microbiota composition to prevent diarrhea in weaned piglets. © 2023 Society of Chemical Industry.

Defining the Role of the Gut Microbiome in the Pathogenesis and Treatment of Lymphoid Malignancies

The gut microbiome is increasingly being recognized as an important immunologic environment, with direct links to the host immune system. The scale of the gut microbiome's genomic repertoire extends the capacity of its host's genome by providing additional metabolic output, and the close communication between gut microbiota and mucosal immune cells provides a continued opportunity for immune education. The relationship between the gut microbiome and the host immune system has important implications for oncologic disease, including lymphoma, a malignancy derived from within the immune system itself. In this review, we explore past and recent discoveries describing the role that bacterial populations play in lymphomagenesis, diagnosis, and therapy. We highlight key relationships within the gut microbiome-immune-oncology axis that present exciting opportunities for directed interventions intended to shape the microbiome for therapeutic effect. We conclude with a limited summary of active clinical trials targeting the microbiome in hematologic malignancies, along with future directions on gut microbiome investigations within lymphoid malignancies.

Gut microbiota and its metabolites - molecular mechanisms and management strategies in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the major microvascular complications of diabetes mellitus and is also one of the serious risk factors in cardiovascular events, end-stage renal disease, and mortality. DKD is associated with the diversified, compositional, and functional alterations of gut microbiota. The interaction between gut microbiota and host is mainly achieved through metabolites, which are small molecules produced by microbial metabolism from exogenous dietary substrates and endogenous host compounds. The gut microbiota plays a critical role in the pathogenesis of DKD by producing multitudinous metabolites. Nevertheless, detailed mechanisms of gut microbiota and its metabolites involved in the occurrence and development of DKD have not been completely elucidated. This review summarizes the specific classes of gut microbiota-derived metabolites, aims to explore the molecular mechanisms of gut microbiota in DKD pathophysiology and progression, recognizes biomarkers for the screening, diagnosis, and prognosis of DKD, as well as provides novel therapeutic strategies for DKD.

The efficacy and safety of Yupingfeng Powder with variation in the treatment of allergic rhinitis: Study protocol for a randomized, double-blind, placebo-controlled trial

Background: Allergic rhinitis (AR) is an upper airways chronic inflammatory disease mediated by IgE, which affects 10%-20% of the population. The mainstay for allergic rhinitis nowadays include steroids and antihistamines, but their effects are less than ideal. Many patients therefore seek Chinese medicine for treatment and Yupingfeng Powder is one of the most common formulae prescribed. In this study, we aim to investigate the efficacy and safety of Yupingfeng Powder with variation for the treatment of allergic rhinitis. Study design: This is a double-blind, randomized, placebo-controlled trial. A 2-week screening period will be implemented, and then eligible subjects with allergic rhinitis will receive interventions of either "Yupingfeng Powder with variation" granules or placebo granules for 8 weeks, followed by post treatment visits at weeks 12 and 16. The change in the Total Nasal Symptom Score (TNSS) will be used as the primary outcome. Discussion: This trail will evaluate the efficacy and safety of Yupingfeng Powder in treating allergic rhinitis. The study may provide the solid evidence of Yupingfeng Powder with variation can produce better clinical efficacy than the placebo granules. Trial registration: ClinicalTrials.gov, identifier NCT04976023.

Probiotic Paenibacillus polymyxa 10 and Lactobacillus plantarum 16 enhance growth performance of broilers by improving the intestinal health

With the ever-growing strict prohibitions on antibiotic growth promoters (AGP) in animal production, in-feed probiotics are becoming attractive alternatives to antibiotics in the poultry industry. To investigate the effects of Paenibacillus polymyxa 10 and Lactobacillus plantarum 16 on the growth performance and intestinal health of broilers, 540 male Cobb 500 broilers of 1 d old were randomly divided into 3 groups with 6 replicates per group and 30 chicks per replicate. Broilers were fed with either a basal diet or basal diets supplemented with 1 × 108 colony-forming units (CFU)/kg P. polymyxa 10 (BSC10) or L. plantarum 16 (Lac16) for 42 d. Results showed that Lac16 treatment improved (P < 0.05) the growth performance (body weight and feed conversion) of broilers at the starter phase, while BSC10 treatment slightly improved (P > 0.05) the growth performance of the starter phase broilers. The increased villus height (P < 0.05) at d 14, 21 and 42 and villus height to crypt depth ratio (P < 0.05) at d 14 and 21 were observed in the ileum of the 2 probiotic groups. Besides, transmission electron microscopy results showed that the 2 probiotics enhanced the intestinal epithelial barrier. Both probiotic treatments up-regulated (P < 0.05) the mRNA expression of fatty acid binding protein 1 (FABP1) and sodium-dependent glucose transporters-1 (SGLT-1) in the ileal mucosa of broilers at d 21. In addition, BSC10 and Lac16 treatments significantly (P < 0.05) increased the relative abundance of short-chain fatty acids-producing bacteria, such as Butyricicoccus pullicaecorum, Faecalibacterium prausnitzii, Lachnospira and Coprococcu, and significantly (P < 0.05) decreased the relative abundance of enteric pathogens (Escherichia coli, Bacteroides fragilis and Shigella sonnei). Furthermore, the 2 probiotic treatments also increased the positive connection among the intestinal microbes and the carbohydrate metabolism-related pathways of the intestinal bacteria (P < 0.05), with decreasing (P < 0.05) nucleotides biosynthesis-related pathways of the intestinal bacteria. Overall, these results suggest that the 2 probiotics, especially Lac16, have a potential beneficial effect on the growth performance and intestinal health of starter phase broilers.

Glucuronides Hydrolysis by Intestinal Microbial β-Glucuronidases (GUS) Is Affected by Sampling, Enzyme Preparation, Buffer pH, and Species

Glucuronides hydrolysis by intestinal microbial β-Glucuronidases (GUS) is an important procedure for many endogenous and exogenous compounds. The purpose of this study is to determine the impact of experimental conditions on glucuronide hydrolysis by intestinal microbial GUS. Standard probe 4-Nitrophenyl β-D-glucopyranoside (pNPG) and a natural glucuronide wogonoside were used as the model compounds. Feces collection time, buffer conditions, interindividual, and species variations were evaluated by incubating the substrates with enzymes. The relative reaction activity of pNPG, reaction rates, and reaction kinetics for wogonoside were calculated. Fresh feces showed the highest hydrolysis activities. Sonication increased total protein yield during enzyme preparation. The pH of the reaction system increased the activity in 0.69–1.32-fold, 2.9–12.9-fold, and 0.28–1.56-fold for mouse, rat, and human at three different concentrations of wogonoside, respectively. The Vmax for wogonoside hydrolysis was 2.37 ± 0.06, 4.48 ± 0.11, and 5.17 ± 0.16 μmol/min/mg and Km was 6.51 ± 0.71, 3.04 ± 0.34, and 0.34 ± 0.047 μM for mouse, rat, and human, respectively. The inter-individual difference was significant (4–6-fold) using inbred rats as the model animal. Fresh feces should be used to avoid activity loss and sonication should be utilized in enzyme preparation to increase hydrolysis activity. The buffer pH should be appropriate according to the species. Inter-individual and species variations were significant.

Unhealthy Lifestyle and Gut Dysbiosis: A Better Understanding of the Effects of Poor Diet and Nicotine on the Intestinal Microbiome

The study of the intestinal or gut microbiome is a newer field that is rapidly gaining attention. Bidirectional communication between gut microbes and the host can impact numerous biological systems regulating immunity and metabolism to either promote or negatively impact the host's health. Habitual routines, dietary choices, socioeconomic status, education, host genetics, medical care and environmental factors can all contribute to the composition of an individual's microbiome. A key environmental factor that may cause negative outcomes is the consumption of nicotine products. The effects of nicotine on the host can be exacerbated by poor dietary choices and together can impact the composition of the gut microbiota to promote the development of metabolic disease including non-alcoholic fatty liver disease. This review explores the contribution of nicotine, poor dietary choices and other unhealthy lifestyle factors to gut dysbiosis.

Human microbiota modulation via QseC sensor kinase mediated in the Escherichia coli O104:H4 outbreak strain infection in microbiome model

Background

The intestinal microbiota plays a crucial role in human health, adjusting its composition and the microbial metabolites protects the gut against invading microorganisms. Enteroaggregative E. coli (EAEC) is an important diarrheagenic pathogen, which may cause acute or persistent diarrhea (≥14 days). The outbreak strain has the potent Shiga toxin, forms a dense biofilm and communicate via QseBC two-component system regulating the expression of many important virulence factors.

Results

Herein, we investigated the QseC histidine sensor kinase role in the microbiota shift during O104:H4 C227–11 infection in the colonic model SHIME® (Simulator of the Human Intestinal Microbial Ecosystem) and in vivo mice model. The microbiota imbalance caused by C227–11 infection affected ỿ-Proteobacteria and Lactobacillus spp. predominance, with direct alteration in intestinal metabolites driven by microbiota change, such as Short-chain fatty acids (SCFA). However, in the absence of QseC sensor kinase, the microbiota recovery was delayed on day 3 p.i., with change in the intestinal production of SCFA, like an increase in acetate production. The higher predominance of Lactobacillus spp. in the microbiota and significant augmented qseC gene expression levels were also observed during C227–11 mice infection upon intestinal depletion. Novel insights during pathogenic bacteria infection with the intestinal microbiota were observed. The QseC kinase sensor seems to have a role in the microbiota shift during the infectious process by Shiga toxin-producing EAEC C227–11.

Conclusions

The QseC role in C227–11 infection helps to unravel the intestine microbiota modulation and its metabolites during SHIME® and in vivo models, besides they contribute to elucidate bacterial intestinal pathogenesis and the microbiota relationships.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02220-3.

Probiotic infant cereal improves children's gut microbiota: Insights using the Simulator of Human Intestinal Microbial Ecosystem (SHIME®)

Infant́s gut microbiota can be modulated by many factors, including mode of delivery, feeding regime, maternal diet/weight and probiotic and prebiotic consumption. The gut microbiota in dysbiosis has been associated with innumerous diseases. In this sense, early childhood intestinal microbiome modulation can be a strategy for disease prevention. This study had the purpose to evaluate the effect of an infant cereal with probiotic (Bifidobacterium animalis ssp. lactis BB-12®) on infant́s intestinal microbiota using SHIME®, which simulates human gastrointestinal conditions. The ascending colon was inoculated with fecal microbiota from three children (2-3 years old). NH₄⁺, short chain fatty acids (SCFASs) and microbiota composition were determined by selective ion electrode, GC/MS and 16S sequencing, respectively. After treatment, butyric acid production increased (p < 0.05) 52% and a decrease in NH₄⁺ production was observed (p < 0.01). The treatment stimulated an increase (p < 0.01) of Lactobacillaceae families, more precisely L. gasseri and L. kefiri. L. gasseri has been associated with the prevention of allergic rhinitis in children and L. kefiri in the prevention of obesity. Thus, infant cereal with BB-12® is able to stimulate the growth of L. gasseri and L. kefiri in a beneficial way, reducing NH₄⁺ and increasing the production of SCFAs, especially butyric acid, in SHIME®.

Tannins extract from Galla Chinensis can protect mice from infection by Enterotoxigenic Escherichia coli O101

Background

Enterotoxigenic Escherichia coli (ETEC) is classically associated with acute secretory diarrhea, which induces 2 million people death in developing countries over a year, predominantly children in the first years of life. Previously, tannins (47.75%) were extracted from Galla Chinensis and prepared as Galla Chinensis oral solution (GOS) which showed significant antidiarrheal activity in a castor oil-induced diarrhea in mice. Whether the tannins extract were also effective in treatment of ETEC-induced diarrhea was determined in this study.

Methods

Mice were randomly divided into 6 groups (n = 22). The mice in the normal and untreated groups were given normal saline. Three GOS-treated groups were received different concentrations of GOS (5, 10 and 15%, respectively) at a dose of 10 mL/kg. Mice in the positive control group were fed with loperamide (10 mg/kg). The treatment with GOS started 3 days before infection with ETEC and continued for 4 consecutive days after infection. On day 3, mice were all infected with one dose of LD₅₀ of ETEC, except those in the normal group. Survival of mice was observed daily and recorded throughout the study. On days 4 and 7, samples were collected from 6 mice in each group.

Results

GOS could increase the survival rate up to 75%, while in the untreated group it is 43.75%. The body weights of mice treated with 15% GOS were significantly increased on day 7 in comparison with the untreated group and the normal group. GOS-treatment recovered the small intestine coefficient enhanced by ETEC-infection. The diarrhea index of mice treated with GOS was significantly decreased. GOS increased the levels of IgG and sIgA in the terminal ileum and decreased the levels of pro-inflammatory cytokines (IFN-γ, TNF-α, IL-1β, IL-6 and IL-8) in serum. GOS could increase the amount of intestinal probiotics, Lactobacilli and Bifidobacteria. GOS could alleviate colon lesions induced by ETEC-infection. GOS showed higher potency than loperamide.

Conclusions

GOS could be a promising drug candidate for treating ETEC infections.

Effects of Chronic Stress on the Fecal Microbiome of Malayan Pangolins (Manis javanica) Rescued from the Illegal Wildlife Trade

Pangolins (scaly anteaters, Pholidota) are among those mammals that are most affected by the international, illegal wildlife trade. Recently, wildlife rescue centers in China became dedicated to rehabilitate confiscated pangolins and prepare them for reintroduction to the wild. Chronic stress is thought to be the main reason for a disturbed microbiota community and a higher mortality rate of pangolin in captivity. In this study, we compared the cortisol levels and the fecal microbiome of Malayan pangolin (Manis javanica) born and reared in captivity (PCB; n = 7) with those rescued from the wildlife trade (PCT; n = 16). Results show that the level of cortisol in PCT was significantly lower than that observed in PCB. There were also significant differences in the composition of the fecal microflora between the two groups, and the diversity of intestinal microbiota was higher in PCB than in PCT. At the phylum level, the bacteria with significant difference between the two groups included Firmicutes and Bacteroides. At the genus level, bacteria such as Bacteroides, Parabacterides, and Clostridium showed significant differences between the two groups. This study proves that chronic stress has a considerable effect on the diversity and composition of fecal microbiota in Malayan pangolin.

Microbe-Driven Genotoxicity in Gastrointestinal Carcinogenesis

The intestinal epithelium serves as a barrier to discriminate the outside from the inside and is in constant exchange with the luminal contents, including nutrients and the microbiota. Pathogens have evolved mechanisms to overcome the multiple ways of defense in the mucosa, while several members of the microbiota can exhibit pathogenic features once the healthy barrier integrity of the epithelium is disrupted. This not only leads to symptoms accompanying the acute infection but may also contribute to long-term injuries such as genomic instability, which is linked to mutations and cancer. While for Helicobacter pylori a link between infection and cancer is well established, many other bacteria and their virulence factors have only recently been linked to gastrointestinal malignancies through epidemiological as well as mechanistic studies. This review will focus on those pathogens and members of the microbiota that have been linked to genotoxicity in the context of gastric or colorectal cancer. We will address the mechanisms by which such bacteria establish contact with the gastrointestinal epithelium-either via an existing breach in the barrier or via their own virulence factors as well as the mechanisms by which they interfere with host genomic integrity.

Coix seed improves growth performance and productivity in post-weaning pigs by reducing gut pH and modulating gut microbiota

Coix seed has traditionally been used in traditional Chinese medicine to fortify the spleen and inhibit dampness, and has shown anticancer effects in humans. However, it is not known whether coix seed improves post-weaning growth performance and productivity, and the mechanism of interaction between coix seed and gut microbiota remains unknown. In this study, we established four groups: (i) control, (ii) antibiotic-fed, (iii) coix seed powder-fed, and (iv) coix seed extract-fed. The feeding experiment was conducted for 4 weeks. Coix seed extract significantly increased average weight gain and reduced the feed/meat ratio in weaned pigs, in addition to reducing the pH of their gastric juice. Further assays demonstrated that coix seed promotes an increase in the density and length of the gastrointestinal villi. Next, 16s sequencing of gut microbiota showed that coix seed significantly increased the abundance of phylum Bacteroidetes and genus Lactobacillus (p < 0.05) and reduced the abundance of phylum Prevotella (p < 0.05) in the gut microbiota. In contrast, the abundance of phylum Bacteroidetes and genus Lactobacillus decreased in the control group and antibiotic group, whereas the abundance of phylum Prevotella increased. Our findings indicate that coix seed improves growth performance and productivity in post-weaning pigs by reducing the pH value of gastric juice, increasing the density and length of gastrointestinal villi, and modulating gut microbiota. Thus, coix seed has good potential for use as a feed supplement in swine production.

Possibilities of early life programming in broiler chickens via intestinal microbiota modulation

The strong selection in search for a higher growth rate in broilers has resulted in adverse effects such as metabolic disorders, low responsiveness of the immune system, and decreased resistance to pathogens. On the other hand, newly hatched chicks rely mostly on innate immune responses until their gut gets colonized with microbiota. In consequence, early access to active substances or bacteria (pre- and post-hatch) is particularly relevant here because in broilers much of the immune system development occurs early in life. Therefore, early stimulation of beneficial microflora is critical, as it affects, to a great extent, the entire life-span of an individual, and also because the nutritional manipulations of the gastrointestinal tract (GIT) microbiome to enhance productivity and health are rather limited by the resilience of the ecosystem once established in the chicken´s gut. Early life or developmental programming is based on the assumption that the development of diseases later in life can be modulated by perturbations or environmental exposures during critical pre- or early post-natal life. Substances such as plant derivatives, Na butyrate, pre- and probiotics, and β-glucans have been shown to induce beneficial microbiological and immunological changes within the GIT, and therefore are potential candidates to be used as tools to manipulate GIT functionality in the young chicken. Accordingly, substances as these might represent promising candidates to study intestinal microbiota/immune system modulation in broilers´ early stages of breeding. In ovo-delivered prebiotics and synbiotics have been shown to have no adverse effect on the development of the immune system in exposed chickens, while being able to affect lymphoid-organs' morphology in chickens. In ovo procedures have also been proposed as means of promoting a healthy microflora in embryonic guts and stimulating maturation of the cellular and humoral immune responses in central and peripheral immune organs, including those in the GIT. The purpose of this presentation is to discuss the potential usefulness of the instruments currently available to induce early life programming in broilers.

Chinese herbal medicine bi min fang for allergic rhinitis: protocol for a double-blind, double-dummy, randomized controlled trial

BACKGROUND

People with allergic rhinitis (AR) often seek help from Chinese medicine due to dissatisfaction with conventional treatments. Lung-spleen qi deficiency syndrome (LSQDS) is the most common type of AR, and the Chinese herbal medicine formula bi min fang (BMF) is commonly prescribed for AR patients with LSQDS. However, direct evidence supporting its efficacy and safety is not available, and its potential mechanism of action remains unclear.

METHODS/DESIGN

This paper presents a double-blind, double-dummy, randomized controlled trial. After a 2-week run-in period, 80 AR patients with LSQDS will be recruited and randomly allocated to the BMF group or the control group in a 1:1 ratio. The patients in the BMF group will receive BMF and the placebo for levocetirizine hydrochloride orally, while the control group participants will receive levocetirizine hydrochloride and the placebo for BMF orally. All participants will receive 4 weeks of treatment and 12 weeks of follow-up. The primary outcome is a change in the Total Nasal Symptom Score (TNSS). Secondary outcomes include changes in scores for the standard version of the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ(S)), and visual analog scale (VAS); changes in serum levels of the cytokines interleukin-4, interferon-γ, transforming growth factor β-1, and interleukin-17; and changes in the gut microbiota composition in the stool. The TNSS, RQLQ(S), and VAS will be recorded at the beginning of, middle of and after the treatment period and at the end of each month in the 3-month follow-up period. Blood and stool samples will be collected at baseline and the end of the treatment. The aforementioned four cytokines will be detected in the serum using enzyme-linked immunosorbent assays, and the stool gut microbiota will be detected using 16S ribosomal ribonucleic acid sequencing. Any side effects of the treatment will be recorded.

DISCUSSION

The results of this trial will provide consolidated evidence of the effect of BMF on AR and the potential mechanism by which BMF acts. This study will be the first to explore the mechanism of action of Chinese herbal medicine on the gut microbiota in AR.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR-IPR-17010970 . Registered on 23 March 2017.

The role of the gut microbiome in systemic inflammatory disease

The role of the gut microbiome in models of inflammatory and autoimmune disease is now well characterized. Renewed interest in the human microbiome and its metabolites, as well as notable advances in host mucosal immunology, has opened multiple avenues of research to potentially modulate inflammatory responses. The complexity and interdependence of these diet-microbe-metabolite-host interactions are rapidly being unraveled. Importantly, most of the progress in the field comes from new knowledge about the functional properties of these microorganisms in physiology and their effect in mucosal immunity and distal inflammation. This review summarizes the preclinical and clinical evidence on how dietary, probiotic, prebiotic, and microbiome based therapeutics affect our understanding of wellness and disease, particularly in autoimmunity.

Interactions between Intestinal Microbiota and Host Immune Response in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract. Although the etiology and pathogenesis of IBD remain unclear, both genetic susceptibility and environmental factors are implicated in the initiation and progression of IBD. Recent studies with experimental animal models and clinical patients indicated that the intestinal microbiota is one of the critical environmental factors that influence nutrient metabolism, immune responses, and the health of the host in various intestinal diseases, including ulcerative colitis and Crohn’s disease. The objective of this review is to highlight the crosstalk between gut microbiota and host immune response and the contribution of this interaction to the pathogenesis of IBD. In addition, potential therapeutic strategies targeting the intestinal micro-ecosystem in IBD are discussed.

Outer membrane vesicles blebbing contributes to B. vulgatus mpk-mediated immune response silencing

The Gram negative intestinal symbiont Bacteroides vulgatus mpk is able to prevent from induction of colonic inflammation in Rag1^-/- mice and promotes immune balance in Il2^-/- mice. These inflammation-silencing effects are associated with B. vulgatus mpk-mediated induction of semi-mature dendritic cells, especially in the colonic lamina propria (cLP). However the beneficial interaction of bacteria with host immune cells is limited due to the existence of a large mucus layer covering the intestinal epithelium. How can intestinal bacteria overcome this physical barrier and contact the host immune system? One mechanism is the production of outer membrane vesicles (OMVs) via ubiquitous blebbing of the outer membrane. These proteoliposomes have the ability to traverse the mucus layer. Hence, OMVs play an important role in immunomodulation and the maintenance of a balanced gut microbiota. Here we demonstrate that the stimulation of bone marrow derived dendritic cells (BMDCs) with isolated OMVs originated from B. vulgatus mpk leads to the induction of a tolerant semi-mature phenotype. Thereby, microbe- associated molecular patterns (MAMPs) delivered by OMVs are crucial for the interaction and the resulting maturation of immune cells. Additional to the binding to host TLR4, a yet unknown ligand to TLR2 is indispensable for the conversion of immature BMDCs into a semi-mature state. Thus, crossing the epithelial mucus layer and directly contact host cells, OMV mediate cross-tolerance via the transport of various Toll-like receptor antigens. These features make OMVs to a key attribute of B. vulgatus mpk for a vigorous acellular prevention and treatment of systemic diseases.

Microbiome, Metabolome and Inflammatory Bowel Disease

Inflammatory Bowel Disease (IBD) is a multifactorial disorder that conceptually occurs as a result of altered immune responses to commensal and/or pathogenic gut microbes in individuals most susceptible to the disease. During Crohn’s Disease (CD) or Ulcerative Colitis (UC), two components of the human IBD, distinct stages define the disease onset, severity, progression and remission. Epigenetic, environmental (microbiome, metabolome) and nutritional factors are important in IBD pathogenesis. While the dysbiotic microbiota has been proposed to play a role in disease pathogenesis, the data on IBD and diet are still less convincing. Nonetheless, studies are ongoing to examine the effect of pre/probiotics and/or FODMAP reduced diets on both the gut microbiome and its metabolome in an effort to define the healthy diet in patients with IBD. Knowledge of a unique metabolomic fingerprint in IBD could be useful for diagnosis, treatment and detection of disease pathogenesis.

Killing of VRE Enterococcus faecalis by commensal strains: Evidence for evolution and accumulation of mobile elements in the absence of competition

Enterococci are members of the gastrointestinal tract of humans and most animals that, over the past 3 decades, have emerged as leading causes of multidrug resistant hospital acquired infection (HAI). In addition to their general hardiness, many traits have entered enterococcal lineages through horizontal gene transfer, which has led to the evolution of pathogenic hospital-associated lineages uniquely adapted for survival and proliferation in the antibiotic perturbed ecology of the gastrointestinal tract. We recently observed that the accretion of mobile genetic elements in the prototype vancomycin resistant E. faecalis, clinical isolate V583, renders it unable to co-exist with native enterococci in healthy human fecal flora. In this addendum, we discuss how these findings inform our understanding of how multidrug resistant enterococci evolve, and the implications for the development of treatments that limit colonization and spread of highly antibiotic refractory microbes of this type.

Equine faecal microbiota transplant: Current knowledge, proposed guidelines and future directions

While certainly not a novel concept, faecal microbiota transplant (FMT) has recently garnered renewed interest in veterinary medicine due to its remarkable success in treating recurrent Clostridium difficile infection (CDI) in man. There is a dearth of information on indications and efficacy of FMT for the treatment of gastrointestinal disorders in the horse; however, based on evidence in man and other veterinary species, and anecdotal reports in horses, FMT may be a useful treatment for selected cases of acute and chronic diarrhoea and inflammatory bowel disease (IBD) in the horse. In the absence of evidence, expert opinion is offered on case selection and FMT procedure. More research is needed to explore the efficacy, indications and optimal preparation, storage and delivery of FMT to horses.

Using bugs as drugs: Microbial ecosystem therapeutics

The human gut harbours a dense and highly diverse microbial ecosystem-the microbiota-that plays an important role in the maintenance of health. Modern lifestyle practices, including widespread antibiotic use, have degraded microbiota diversity, compromising the integrity of this vital ecosystem and creating susceptibility to diseases such as Clostridium difficile infection. Treatment of patients to restore the diversity of the gut microbiota offers a logical solution to disease. Although fecal microbial therapy (FMT) has started to gain traction as an effective method to effect this restoration, it is not without risks and there are significant barriers to its implementation in the clinic. Some of the risks and challenges with FMT are addressed by microbial ecosystem therapeutics (MET), an alternative approach to FMT that uses selected, defined microbial ecosystems to redress microbiota balance and functionality. The time has come for the use of bugs as drugs.

Plasma metabolomic profiles and immune responses of piglets after weaning and challenge with E. coli

Background

The processes of weaning and exposure to pathogenic bacteria induce stress responses, which may alter the metabolism. In this study, we investigated the changes in plasma metabolites and immune responses in piglets in response to the stress induced by weaning and Escherichia coli challenge.

Results

Fecal dry matter decreased (P = 0.003) and nearly half (44.4%) the piglets developed diarrhea on day 2 and 3 postweaning. The concentration of plasma immunoglobulin A was higher (P < 0.001) on day 11 postweaning than on day 0 or 4 postweaning. The levels of white blood cells increased continuously (P < 0.001) from day 0 to day 11 postweaning. Differences in the percentages of neutrophils (P = 0.029) and lymphocytes (P = 0.022) were seen, but the neutrophil/lymphocyte ratio did not differ in the period after weaning. A clear separation of the metabolomic profile data for day 0 and day 4 postweaning was observed with a principal components analysis (PCA) scores plot, and the data for day 11 were located between those for day 0 and day 4 postweaning. The plasma levels of proline, taurine, and carnitine were higher, whereas those of betaine, creatine, L-arginine and acetylcarnitine were lower on day 4 postweaning than on day 0. Levels of lysophosphatidylcholine and phosphatidylcholine were either higher or lower after weaning, depending on the chain lengths or characters of these metabolites.

Conclusions

Our results show a clear separation in the plasma metabolomic profiles of piglets that corresponded to the fecal responses to stress on the piglets induced by weaning or exposure to a pathogen (E. coli). These plasma metabolite profiles suggest that the challenges induced proinflammatory responses in the piglets, resulting in postweaning diarrhea, which was associated with higher concentrations of IgA in the plasma.

Recent progress on the role of gut microbiota in the pathogenesis of inflammatory bowel disease

In recent years investigations of inflammatory bowel disease (IBD) have advanced rapidly with regard to the relationship between the host immune response and gut microbiota. Patients with IBD have been shown to have an abnormal composition of gut microbiota and host immune dysregulation. Abnormal components of gut microbiota, to which the host mounts aberrant immune responses in genetically vulnerable individuals, appear to play a critical role in the pathogenesis of IBD. Therefore, inappropriate innate and adaptive host immune responses to abnormal components of gut microbiota and their products form the basis of IBD pathogenesis. Modern molecular genetic methods should be utilized to help to illuminate the pathogenetic mechanism of IBD and to develop personalized therapeutic strategies for this disease.

Plasmacytoid dendritic cells are crucial in Bifidobacterium adolescentis-mediated inhibition of Yersinia enterocolitica infection

In industrialized countries bacterial intestinal infections are commonly caused by enteropathogenic Enterobacteriaceae. The interaction of the microbiota with the host immune system determines the adequacy of an appropriate response against pathogens. In this study we addressed whether the probiotic Bifidobacterium adolescentis is protective during intestinal Yersinia enterocolitica infection. Female C57BL/6 mice were fed with B. adolescentis, infected with Yersinia enterocolitica, or B. adolescentis fed and subsequently infected with Yersinia enterocolitica. B. adolescentis fed and Yersinia infected mice were protected from Yersinia infection as indicated by a significantly reduced weight loss and splenic Yersinia load when compared to Yersinia infected mice. Moreover, protection from infection was associated with increased intestinal plasmacytoid dendritic cell and regulatory T-cell frequencies. Plasmacytoid dendritic cell function was investigated using depletion experiments by injecting B. adolescentis fed, Yersinia infected C57BL/6 mice with anti-mouse PDCA-1 antibody, to deplete plasmacytoid dendritic cells, or respective isotype control. The B. adolescentis-mediated protection from Yersinia dissemination to the spleen was abrogated after plasmacytoid dendritic cell depletion indicating a crucial function for pDC in control of intestinal Yersinia infection. We suggest that feeding of B. adolescentis modulates the intestinal immune system in terms of increased plasmacytoid dendritic cell and regulatory T-cell frequencies, which might account for the B. adolescentis-mediated protection from Yersinia enterocolitica infection.

Impact of chronic exposure to low doses of chlorpyrifos on the intestinal microbiota in the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) and in the rat

The impact of the insecticide chlorpyrifos (CPF) on the mammalian digestive system has been poorly described. The present study aimed at evaluating the effect of chronic, low-dose exposure to CPF on the composition of the gut microbiota in a Simulator of the Human Intestinal Microbial Ecosystem: the SHIME and in rats. The SHIME comprises six reactor vessels (stomach to colon). The colonic segments were inoculated with feces from healthy humans. Then, the simulator was exposed to a daily dose of 1 mg of CPF for 30 days. The changes over time in the populations of bacteria were examined at different time points: prior to pesticide exposure (as a control) and after exposure. In parallel, pregnant rats were gavaged daily with 1 mg/kg of CPF (or vehicle) until the pups were weaned. Next, the rats were gavaged with same dose of CPF until 60 days of age (adulthood). Then, samples of different parts of the digestive tract were collected under sterile conditions for microbiological assessment. Chronic, low-dose exposure to CPF in the SHIME and in the rat was found to induce dysbiosis in the microbial community with, in particular, proliferation of subpopulations of some strains and a decrease in the numbers of others bacteria. In compliance with European guidelines, the use of the SHIME in vitro tool would help to (1) elucidate the final health effect of toxic agents and (2) minimize (though not fully replace) animal testing. Indeed, certain parameters would still have to be studied further in vivo.