Long-term impact of oral vancomycin, ciprofloxacin and metronidazole on the gut microbiota in healthy humans

OBJECTIVES

The impact of combination antibiotic therapy on the composition of the intestinal microbiota remains ill-defined. We aimed to assess the effect of a 1 week antibiotic regimen on the intestinal microbiota of healthy humans for a period of up to 31 months.

PATIENTS AND METHODS

Thirteen healthy adult men received either no treatment or oral broad-spectrum antibiotics (ciprofloxacin, vancomycin and metronidazole) for 7 days. At four timepoints (prior to treatment, on day 9, day 49 and 8-31 months later) faecal samples were collected and analysed using 16S RNA gene sequencing.

RESULTS

The short-term impact of broad-spectrum antibiotics on the gut microbiota was profound, with a loss of diversity and drastic shifts in community composition. In addition, antibiotics significantly reduced the abundance of bacterial taxa with important metabolic functions, such as the production of butyrate. The microbiota showed a remarkable return towards baseline after 8-31 months, but community composition often remained altered from its initial state.

CONCLUSIONS

These findings suggest that combined treatment with vancomycin, ciprofloxacin and metronidazole has a profound and long-lasting effect on microbiota composition, the consequences of which remain largely unknown.

Akkermansia and Microbial Degradation of Mucus in Cats and Dogs: Implications to the Growing Worldwide Epidemic of Pet Obesity

Akkermansia muciniphila is a mucin-degrading bacterium that has shown the potential to provide anti-inflammatory and anti-obesity effects in mouse and man. We here focus on companion animals, specifically cats and dogs, and evaluate the microbial degradation of mucus and its health impact in the context of the worldwide epidemic of pet obesity. A literature survey revealed that the two presently known Akkermansia spp., A. muciniphila and A. glycaniphila, as well as other members of the phylum of Verrucomicrobia seem to be neither very prevalent nor abundant in the digestive tract of cats and dog. While this may be due to methodological aspects, it suggests that bacteria related to Akkermansia are not the major mucus degraders in these pets and hence other mucus-utilizing taxa may deserve attention. Hence, we will discuss the potential of these endogenous mucus utilizers and dietary interventions to boost these as well as the use of Akkermansia spp. related bacteria or their components as strategies to target feline and canine obesity.

Pasteurized Akkermansia muciniphila protects from fat mass gain but not from bone loss

Probiotic bacteria can protect from ovariectomy (ovx)-induced bone loss in mice. Akkermansia muciniphila is considered to have probiotic potential due to its beneficial effect on obesity and insulin resistance. The purpose of the present study was to determine if treatment with pasteurized Akkermansia muciniphila (pAkk) could prevent ovx-induced bone loss. Mice were treated with vehicle or pAkk for 4 wk, starting 3 days before ovx or sham surgery. Treatment with pAkk reduced fat mass accumulation confirming earlier findings. However, treatment with pAkk decreased trabecular and cortical bone mass in femur and vertebra of gonadal intact mice and did not protect from ovx-induced bone loss. Treatment with pAkk increased serum parathyroid hormone (PTH) levels and increased expression of the calcium transporter Trpv5 in kidney suggesting increased reabsorption of calcium in the kidneys. Serum amyloid A 3 (SAA3) can suppress bone formation and mediate the effects of PTH on bone resorption and bone loss in mice and treatment with pAkk increased serum levels of SAA3 and gene expression of Saa3 in colon. Moreover, regulatory T cells can be protective of bone and pAkk-treated mice had decreased number of regulatory T cells in mesenteric lymph nodes and bone marrow. In conclusion, treatment with pAkk protected from ovx-induced fat mass gain but not from bone loss and reduced bone mass in gonadal intact mice. Our findings with pAkk differ from some probiotics that have been shown to protect bone mass, demonstrating that not all prebiotic and probiotic factors have the same effect on bone.

Treatment with Anaerobutyricum soehngenii: a pilot study of safety and dose-response effects on glucose metabolism in human subjects with metabolic syndrome

Dysbiosis of the intestinal microbiota has been implicated in insulin resistance, although evidence regarding causality in humans is scarce. We performed a phase I/II dose-finding and safety study on the effect of oral intake of the anaerobic butyrogenic strain Anaerobutyricum soehngenii on glucose metabolism in 24 subjects with metabolic syndrome. We found that treatment with A. soehngenii was safe and observed a significant correlation between the measured fecal abundance of administered A. soehngenii and improvement in peripheral insulin sensitivity after 4 weeks of treatment. This was accompanied by an altered microbiota composition and a change in bile acid metabolism. Finally, we show that metabolic response upon administration of A. soehngenii (defined as improved insulin sensitivity 4 weeks after A. soehngenii intake) is dependent on microbiota composition at baseline. These data in humans are promising, but additional studies are needed to reproduce our findings and to investigate long-term effects, as well as other modes of delivery.

Bridging Bacteria and the Gut: Functional Aspects of Type IV Pili

Cell-surface-located proteinaceous appendages, such as flagella and fimbriae or pili, are ubiquitous in bacterial communities. Here, we focus on conserved type IV pili (T4P) produced by bacteria in the intestinal tract, one of the most densely populated human ecosystems. Computational analysis revealed that approximately 30% of known intestinal bacteria are predicted to produce T4P. To rationalize how T4P allow intestinal bacteria to interact with their environment, other microbiota members, and host cells, we review their established role in gut commensals and pathogens with respect to adherence, motility, and biofilm formation, as well as protein secretion and DNA uptake. This work indicates that T4P are widely spread among the known members of the intestinal microbiota and that their contribution to human health might be underestimated.

Akkermansia muciniphila reduces Porphyromonas gingivalis-induced inflammation and periodontal bone destruction

AIM

Akkermansia muciniphila is a beneficial gut commensal, whose anti-inflammatory properties have recently been demonstrated. This study aimed to evaluate the effect of A. muciniphila on Porphyromonas gingivalis elicited inflammation.

MATERIAL AND METHODS

In lean and obese mice, A. muciniphila was administered in P. gingivalis-induced calvarial abscess and in experimental periodontitis model (EIP). Bone destruction and inflammation were evaluated by histomorphometric analysis. In vitro, A. muciniphila was co-cultured with P. gingivalis, growth and virulence factor expression was evaluated. Bone marrow macrophages (BMMϕ) and gingival epithelial cells (TIGK) were exposed to both bacterial strains, and the expression of inflammatory mediators, as well as tight junction markers, was analysed.

RESULTS

In a model of calvarial infection, A. muciniphila decreased inflammatory cell infiltration and bone destruction. In EIP, treatment with A. muciniphila resulted in a decreased alveolar bone loss. In vitro, the addition of A. muciniphila to P. gingivalis-infected BMMϕ increased anti-inflammatory IL-10 and decreased IL-12. Additionally, A. muciniphila exposure increases the expression of junctional integrity markers such as integrin-β1, E-cadherin and ZO-1 in TIGK cells. A. muciniphila co-culture with P. gingivalis reduced gingipains mRNA expression.

DISCUSSION

This study demonstrated the protective effects of A. muciniphila administration and may open consideration to its use as an adjunctive therapeutic agent to periodontal treatment.

Development of omics-based protocols for the microbiological characterization of multi-strain formulations marketed as probiotics: the case of VSL#3

The growing commercial interest in multi-strain formulations marketed as probiotics has not been accompanied by an equal increase in the evaluation of quality levels of these biotechnological products. The multi-strain product VSL#3 was used as a model to setup a microbiological characterization that could be extended to other formulations with high complexity. Shotgun metagenomics by deep Illumina sequencing was applied to DNA isolated from the commercial VSL#3 product to confirm strains identity safety and composition. Single-cell analysis was used to evaluate the cell viability, and β-galactosidase and urease activity have been used as marker to monitor the reproducibility of the production process. Similarly, these lots were characterized in detail by a metaproteomics approach for which a robust protein extraction protocol was combined with advanced mass spectrometry. The results identified over 1600 protein groups belonging to all strains present in the VSL#3 formulation. Of interest, only 3.2 % proteins showed significant differences mainly related to small variations in strain abundance. The protocols developed in this study addressed several quality criteria that are relevant for marketed multi-strain products and these represent the first efforts to define the quality of complex probiotic formulations such as VSL#3.

Mutual Metabolic Interactions in Co-cultures of the Intestinal Anaerostipes rhamnosivorans With an Acetogen, Methanogen, or Pectin-Degrader Affecting Butyrate Production

The human intestinal tract harbors diverse and complex microbial communities that have a vast metabolic capacity including the breakdown of complex carbohydrates into short chain fatty acids, acetate, propionate, and butyrate. As butyrate is beneficial for gut health there is much attention on butyrogenic bacteria and their role in the colonic anaerobic food chain. However, our understanding how production of butyrate by gut microorganisms is controlled by interactions between different species and environmental nutrient availability is very limited. To address this, we set up experimental in vitro co-culture systems to study the metabolic interactions of Anaerostipes rhamnosivorans, a butyrate producer with each of its partners; Blautia hydrogenotrophica, an acetogen; Methanobrevibacter smithii, a methanogen and Bacteroides thetaiotaomicron, a versatile degrader of plant cell wall pectins; through corresponding specific cross-feeding. In all co-cultures, A. rhamnosivorans was able to benefit from its partner for enhanced butyrate formation compared to monocultures. Interspecies transfer of hydrogen or formate from A. rhamnosivorans to the acetogen B. hydrogenotrophica and in turn of acetate from the acetogen to the butyrogen were essential for butyrate formation. A. rhamnosivorans grown on glucose supported growth of M. smithii via interspecies formate/hydrogen transfer enhancing butyrate formation. In the co-culture with pectin, lactate was released by B. thetaiotaomicron which was concomitantly used by A. rhamnosivorans for the production of butyrate. Our findings indicate enhanced butyrate formation through microbe-microbe interactions between A. rhamnosivorans and an acetogen, a methanogen or a pectin-degrader. Such microbial interactions enhancing butyrate formation may be beneficial for colonic health.

2843. Maternal Fecal Transplantation to Infants Born by Cesarean Section: Safety and Feasibility

Background

A complication of cesarean section delivery is its interference with the normal intestinal colonization of the infant, affecting the development of immune system in early life—a process that has been associated with long-term morbidity, such as allergy and diabetes. We evaluated, in CS-delivered infants, whether the normal intestinal microbiome and its early life development could be restored by immediate postnatal transfer of maternal fecal microbiota to the newborn.

Methods

Seventeen healthy mothers with planned elective CS were recruited and screened thoroughly for infections, after which 7 mothers were included in the study. A fecal sample was processed according to a transplantation protocol and an aliquot (3–7 mg) was orally administered in breast-milk to the newborn during the first feeding. The infants were followed and fecal samples were gathered during the first 12 weeks of age and subsequently at the age of 8–18 months.

Results

The bacterial communities in the fecal samples of the mothers and their offspring were analyzed by sequencing of 16S rRNA amplicons from isolated fecal DNA and compared with that of 11 nontreated CS-delivered infants and 34 vaginally delivered infants. The fecal microbiota at 3 and 12 weeks was similar between treated CS and vaginally delivered infants, in contrast to that of the untreated CS-delivered infants both in overall composition (P = 0.001, Figure) and development of early-life signature bacteria, i.e., bacteroides and bifidobacteria and clostridia (P < 0.0001).

Conclusion

The seeding of maternal fecal microbes to the newborn intestine can be safely and successfully mimicked in elective CS by transferring a small amount of maternal fecal microbiome orally to the newborn infant. In these infants, this process results in a microbial development that is highly similar to that of the vaginally born infants, and provides support for the hypothesis that microbial colonization in early life results from a maternal fecal transfer.

Disclosures

All Authors: No reported Disclosures.

Molecular ecology of the yet uncultured bacterial Ct85-cluster in the mammalian gut

In our previous studies on irritable bowel syndrome (IBS) -associated microbiota by molecular methods, we demonstrated that a particular 16S rRNA gene amplicon was more abundant in the feces of healthy subjects or mixed type IBS (IBS-M) -sufferers than in the feces of individuals with diarrhea-type IBS (IBS-D). In the current study, we demonstrated that this, so called Ct85-amplicon, consists of a cluster of very heterogeneous 16S rRNA gene sequences, and defined six 16S rRNA gene types, a to f, within this cluster, each representing a novel species-, genus- or family level taxon. We then designed specific PCR primers for these sequence types, mapped the distribution of the Ct85-cluster sequences and that of the newly defined sequence types in several animal species and compared the sequence types present in the feces of healthy individuals and IBS sufferers using two IBS study cohorts, Finnish and Dutch. Various Ct85-cluster sequence types were detected in the fecal samples of several companion and production animal species with remarkably differing prevalences and abundances. The Ct85 sequence type composition of swine closely resembled that of humans. One of the five types (d) shared between humans and swine was not present in any other animals tested, while one sequence type (b) was found only in human samples. In both IBS study cohorts, one type (e) was more prevalent in healthy individuals than in the IBS-M group. By revealing various sequence types in the widespread Ct85-cluster and their distribution, the results improve our understanding of these uncultured bacteria, which is essential for future efforts to cultivate representatives of the Ct85-cluster and reveal their roles in IBS.

Enhanced nutrient supply and intestinal microbiota development in very low birth weight infants

BACKGROUND

Promoting a healthy intestinal microbiota may have positive effects on short- and long-term outcomes in very low birth weight (VLBW; BW < 1500 g) infants. Nutrient supply influences the intestinal microbiota.

METHODS

Fifty VLBW infants were randomized to an intervention group receiving enhanced nutrient supply or a control group. Fecal samples from 45 infants collected between birth and discharge were analyzed using 16S ribosomal RNA (rRNA) amplicon sequencing.

RESULTS

There was considerable individual variation in microbiota development. Microbial richness decreased towards discharge in the controls compared to the intervention group. In the intervention group, there was a greater increase in diversity among moderately/very preterm (MVP, gestational age ≥ 28 weeks) infants and a steeper decrease in relative Staphylococcus abundance in extremely preterm (EP, gestational age < 28 weeks) infants as compared to controls. Relative Bifidobacterium abundance tended to increase more in MVP controls compared to the intervention group. Abundance of pathogens was not increased in the intervention group. Higher relative Bifidobacterium abundance was associated with improved weight gain.

CONCLUSION

Nutrition may affect richness, diversity, and microbiota composition. There was no increase in relative abundance of pathogens among infants receiving enhanced nutrient supply. Favorable microbiota development was associated with improved weight gain.

The Gut Microbiota in the First Decade of Life

Appreciation of the importance of the gut microbiome is growing, and it is becoming increasingly relevant to identify preventive or therapeutic solutions targeting it. The composition and function of the gut microbiota are relatively well described for infants (less than 3 years) and adults, but have been largely overlooked in pre-school (3-6 years) and primary school-age (6-12 years) children, as well as teenagers (12-18 years). Early reports suggested that the infant microbiota would attain an adult-like structure at the age of 3 years, but recent studies have suggested that microbiota development may take longer. This development time is of key importance because there is evidence to suggest that deviations in this development may have consequences in later life. In this review, we provide an overview of current knowledge concerning the gut microbiota, its evolution, variation, and response to dietary challenges during the first decade of life with a focus on healthy pre-school and primary school-age children (up to 12 years) from various populations around the globe. This knowledge should facilitate the identification of diet-based approaches targeting individuals of this age group, to promote the development of a healthy microbiota in later life.

Bicistronic Design-Based Continuous and High-Level Membrane Protein Production in Escherichia coli

Escherichia coli has been widely used as a platform microorganism for both membrane protein production and cell factory engineering. The current methods to produce membrane proteins in this organism require the induction of target gene expression and often result in unstable, low yields. Here, we present a method combining a constitutive promoter with a library of bicistronic design (BCD) elements, which enables inducer-free, tuned translation initiation for optimal protein production. Our system mediates stable, constitutive production of bacterial membrane proteins at yields that outperform those obtained with E. coli Lemo21(DE3), the current gold standard for bacterial membrane protein production. We envisage that the continuous, fine-tunable, and high-level production of membrane proteins by our method will greatly facilitate their study and their utilization in engineering cell factories.

Universal membrane-labeling combined with expression of Katushka far-red fluorescent protein enables non-invasive dynamic and longitudinal quantitative 3D dual-color fluorescent imaging of multiple bacterial strains in mouse intestine

BACKGROUND

The human gastrointestinal (GI) tract microbiota has been a subject of intense research throughout the 3rd Millennium. Now that a general picture about microbiota composition in health and disease is emerging, questions about factors determining development of microbiotas with specific community structures will be addressed. To this end, usage of murine models for colonization studies remains crucial. Optical in vivo imaging of either bioluminescent or fluorescent bacteria is the basis for non-invasive detection of intestinal colonization of bacteria. Although recent advances in in vivo fluorescence imaging have overcome many limitations encountered in bioluminescent imaging of intestinal bacteria, such as requirement for live cells, high signal attenuation and 2D imaging, the method is still restricted to bacteria for which molecular cloning tools are available.

RESULTS

Here, we present usage of a lipophilic fluorescent dye together with Katushka far-red fluorescent protein to establish a dual-color in vivo imaging system to monitor GI transit of different bacterial strains, suitable also for strains resistant to genetic labeling. Using this system, we were able to distinguish two different E. coli strains simultaneously and show their unique transit patterns. Combined with fluorescence molecular tomography, these distinct strains could be spatially and temporally resolved and quantified in 3D.

CONCLUSIONS

Developed novel method for labeling microbes and identify their passage both temporally and spatially in vivo makes now possible to monitor all culturable bacterial strains, also those that are resistant to conventional genetic labeling.

Supplementation with Akkermansia muciniphila in overweight and obese human volunteers: a proof-of-concept exploratory study

Metabolic syndrome is characterized by a constellation of comorbidities that predispose individuals to an increased risk of developing cardiovascular pathologies as well as type 2 diabetes mellitus (T2DM)¹. The gut microbiota is considered as a new key contributor involved in the onset of obesity-related disorders². In humans, studies have provided evidence for a negative correlation between Akkermansia muciniphila abundance and overweight, obesity, untreated T2DM, or hypertension^3–8. As the administration of A.muciniphila has never been investigated in humans, we conducted a randomized double-blind placebo-controlled pilot study in overweight/obese insulin resistant volunteers, 40 were enroled and 32 completed the trial. The primary endpoints were on safety, tolerability and metabolic parameters (i.e., insulin resistance, circulating lipids, visceral adiposity, body mass). The secondary outcomes were the gut barrier function (i.e., plasma lipopolysacharrides (LPS) and gut microbiota composition. In this single-center study, we demonstrated that daily oral supplementation of 10¹⁰ bacteria either alive or pasteurized A.muciniphila for 3 months was safe and well tolerated. Compared to the Placebo, pasteurized A.muciniphila improved insulin sensitivity (+28.62±7.02%, P=0.002), reduced insulinemia (-34.08±7.12%, P=0.006) and plasma total cholesterol (-8.68±2.38%, P=0.02). Pasteurized A.muciniphila supplementation slightly decreased body weight (-2.27±0.92kg, P=0.091) as compared to the Placebo group, and fat mass (-1.37±0.82kg, P=0.092) and hip circumference (-2.63±1.14cm, P = 0.091) as compared to baseline. After 3 months of supplementation, A.muciniphila reduced the levels of relevant blood markers of liver dysfunction and inflammation while the overall gut microbiome structure was unaffected. In conclusion, this proof-of-concept study (NCT02637115) shows that the intervention was safe and well-tolerated and that the supplementation with A.muciniphila improves several metabolic paramaters.

Cohort profile: Finnish Health and Early Life Microbiota (HELMi) longitudinal birth cohort

PURPOSE

HELMi (Health and Early Life Microbiota) is a longitudinal, prospective general population birth cohort, set up to identify environmental, lifestyle and genetic factors that modify the intestinal microbiota development in the first years of life and their relation to child health and well-being.

PARTICIPANTS

The HELMi cohort consists of 1055 healthy term infants born in 2016-2018 mainly at the capital region of Finland and their parents. The intestinal microbiota development of the infants is characterised based on nine, strategically selected, faecal samples and connected to extensive online questionnaire-collected metadata at weekly to monthly intervals focusing on the diet, other exposures and family's lifestyle as well as the health and growth of the child. Motor and cognitive developmental screening takes place at 18 months. Infant's DNA sample, mother's breast milk sample and both parent's spot faecal samples have been collected.

FINDINGS TO DATE

The mean age of the mothers was 32.8 (SD 4.1) and fathers/coparents 34.8 (5.3) years at the time of enrolment. Seventeen percentage (n=180) of the infants were born by caesarean section. Just under half (49%) were firstborns; 50.7% were males. At 3 months of age, 86% of the babies were exclusively breastfed and 2% exclusively formula-fed.

FUTURE PLANS

The current follow-up from pregnancy to first 24 months will be completed in March 2020, totalling to over 10 000 biological samples and over 50 000 questionnaire entries. The results are expected to identify environmental and host factors that affect early gut microbiota development and health, and hence give indications of how to prevent or reverse microbiota perturbations in infancy. This prospective cohort will be followed up further to identify how the early microbiota relates to later health outcomes, especially weight gain, infections and allergic and other chronic diseases.

TRIAL REGISTRATION NUMBER

NCT03996304; Pre-results.

Anaerobic Degradation of N-ε-Carboxymethyllysine, a Major Glycation End-Product, by Human Intestinal Bacteria

Modifications of lysine contribute to the amount of dietary advanced glycation end-products reaching the colon. However, little is known about the ability of intestinal bacteria to metabolize dietary N-ε-carboxymethyllysine (CML). Successive transfers of fecal microbiota in growth media containing CML were used to identify and isolate species able to metabolize CML under anaerobic conditions. From our study, only donors exposed to processed foods degraded CML, and anaerobic bacteria enrichments from two of them used 77 and 100% of CML. Oscillibacter and Cloacibacillus evryensis increased in the two donors after the second transfer, highlighting that the bacteria from these taxa could be candidates for anaerobic CML degradation. A tentative identification of CML metabolites produced by a pure culture of Cloacibacillus evryensis was performed by mass spectrometry: carboxymethylated biogenic amines and carboxylic acids were identified as CML degradation products. The study confirmed the ability of intestinal bacteria to metabolize CML under anoxic conditions.

Gender-Specific Associations Between Saliva Microbiota and Body Size

OBJECTIVE

The human intestinal microbiota likely play an important role in the development of overweight and obesity. However, the associations between saliva microbiota and body mass index (BMI) have been sparsely studied. The aim of this study was to identify the associations between saliva microbiota and body size in Finnish children.

METHODS

The saliva microbiota of 900 Finnish children, aged 11-14 years with measured height and weight, was characterized using 16S rRNA (V3-V4) sequencing.

RESULTS

The core saliva microbiota consisted of 14 genera that were present in more than 95% of the Finnish children. The saliva microbiota profiles were gender-specific with higher alpha-diversity in boys than girls and significant differences between the genders in community composition and abundances. Alpha-diversity differed between normal weight and overweight girls and between normal weight and obese boys. The composition was dissimilar between normal weight and obese girls, but not in boys. The relative abundance profiles differed according to body size. Decrease in commensal saliva bacteria were observed in all the body sizes when compared to normal weight children. Notably, the relative abundance of bacteria related to, Veillonella, Prevotella, Selenomonas, and Streptococcus was reduced in obese children.

CONCLUSION

Saliva microbiota diversity and composition were significantly associated with body size and gender in Finnish children. Body size-specific saliva microbiota profiles open new avenues for studying the potential roles of microbiota in weight development and management.

The Effect of Allogenic Versus Autologous Fecal Microbiota Transfer on Symptoms, Visceral Perception and Fecal and Mucosal Microbiota in Irritable Bowel Syndrome: A Randomized Controlled Study

OBJECTIVES

Fecal microbiota transfer (FMT) is suggested as a potential treatment for patients with irritable bowel syndrome (IBS). We aimed to study the effect of allogenic and autologous FMT on IBS symptoms, visceral sensitivity, and compositional changes in fecal and mucosa-adherent microbiota.

METHODS

Seventeen patients with IBS were randomized either to receive fecal material from a healthy donor (allogenic) or to receive their own fecal material (autologous). The fecal material was administered into the cecum by whole colonoscopy after bowel cleansing.

RESULTS

No significant differences were found between the allogenic and the autologous FMT regarding symptom scores. However, symptom scores of patients receiving allogenic fecal material significantly decreased after FMT compared with baseline (P = 0.02), which was not the case in the autologous group (P = 0.16). Visceral sensitivity was not affected except for a small beneficial effect on urge scores in the autologous group (P < 0.05). While both fecal and mucosa-adherent microbiota of some patients shifted to their respective donor's fecal microbiota, some patients showed no relevant microbial changes after allogenic FMT. Large compositional shifts in fecal and mucosa-adherent microbiota also occurred in the autologous group.

CONCLUSIONS

This study showed that a single FMT by colonoscopy may have beneficial effects in IBS; however, the allogenic fecal material was not superior to the autologous fecal material. This suggests that bowel cleansing prior to the colonoscopy and/or processing of the fecal material as part of the FMT routine contribute to symptoms and gut microbiota composition changes in IBS.

Biotechnology of health-promoting bacteria

Over the last decade, there has been an increasing scientific and public interest in bacteria that may positively contribute to human gut health and well-being. This interest is reflected by the ever-increasing number of developed functional food products containing health-promoting bacteria and reaching the market place as well as by the growing revenue and profits of notably bacterial supplements worldwide. Traditionally, the origin of probiotic-marketed bacteria was limited to a rather small number of bacterial species that mostly belong to lactic acid bacteria and bifidobacteria. Intensifying research efforts on the human gut microbiome offered novel insights into the role of human gut microbiota in health and disease, while also providing a deep and increasingly comprehensive understanding of the bacterial communities present in this complex ecosystem and their interactions with the gut-liver-brain axis. This resulted in rational and systematic approaches to select novel health-promoting bacteria or to engineer existing bacteria with enhanced probiotic properties. In parallel, the field of gut microbiomics developed into a fertile framework for the identification, isolation and characterization of a phylogenetically diverse array of health-promoting bacterial species, also called next-generation therapeutic bacteria. The present review will address these developments with specific attention for the selection and improvement of a selected number of health-promoting bacterial species and strains that are extensively studied or hold promise for future food or pharma product development.

Akkermansia muciniphila ameliorates the age-related decline in colonic mucus thickness and attenuates immune activation in accelerated aging Ercc1 -/Δ7 mice

BACKGROUND

The use of Akkermansia muciniphila as potential therapeutic intervention is receiving increasing attention. Health benefits attributed to this bacterium include an improvement of metabolic disorders and exerting anti-inflammatory effects. The abundance of A. muciniphila is associated with a healthy gut in early mid- and later life. However, the effects of A. muciniphila on a decline in intestinal health during the aging process are not investigated yet. We supplemented accelerated aging Ercc1 -/Δ7 mice with A. muciniphila for 10 weeks and investigated histological, transcriptional and immunological aspects of intestinal health.

RESULTS

The thickness of the colonic mucus layer increased about 3-fold after long-term A. muciniphila supplementation and was even significantly thicker compared to mice supplemented with Lactobacillus plantarum WCFS1. Colonic gene expression profiles pointed towards a decreased expression of genes and pathways related to inflammation and immune function, and suggested a decreased presence of B cells in colon. Total B cell frequencies in spleen and mesenteric lymph nodes were not altered after A. muciniphila supplementation. Mature and immature B cell frequencies in bone marrow were increased, whereas B cell precursors were unaffected. These findings implicate that B cell migration rather than production was affected by A. muciniphila supplementation. Gene expression profiles in ileum pointed toward a decrease in metabolic- and immune-related processes and antimicrobial peptide production after A. muciniphila supplementation. Besides, A. muciniphila decreased the frequency of activated CD80+CD273- B cells in Peyer's patches. Additionally, the increased numbers of peritoneal resident macrophages and a decrease in Ly6Cint monocyte frequencies in spleen and mesenteric lymph nodes add evidence for the potentially anti-inflammatory properties of A. muciniphila.

CONCLUSIONS

Altogether, we show that supplementation with A. muciniphila prevented the age-related decline in thickness of the colonic mucus layer and attenuated inflammation and immune-related processes at old age. This study implies that A. muciniphila supplementation can contribute to a promotion of healthy aging.

The Effect of Psyllium Husk on Intestinal Microbiota in Constipated Patients and Healthy Controls

Psyllium is a widely used treatment for constipation. It traps water in the intestine increasing stool water, easing defaecation and altering the colonic environment. We aimed to assess the impact of psyllium on faecal microbiota, whose key role in gut physiology is being increasingly recognised. We performed two randomised, placebo-controlled, double-blinded trials comparing 7 days of psyllium with a placebo (maltodextrin) in 8 healthy volunteers and 16 constipated patients respectively. We measured the patients’ gastrointestnal (GI) transit, faecal water content, short-chain fatty acid (SCFA) and the stool microbiota composition. While psyllium supplement had a small but significant effect on the microbial composition of healthy adults (increasing Veillonella and decreasing Subdoligranulum), in constipated subjects there were greater effects on the microbial composition (increased Lachnospira, Faecalibacterium, Phascolarctobacterium, Veillonella and Sutterella and decreased uncultured Coriobacteria and Christensenella) and alterations in the levels of acetate and propionate. We found several taxa to be associated with altered GI transit, SCFAs and faecal water content in these patients. Significant increases in three genera known to produce butyrate, Lachnospira, Roseburia and Faecalibacterium, correlated with increased faecal water. In summary, psyllium supplementation increased stool water and this was associated with significant changes in microbiota, most marked in constipated patients.