Carlos Poveda

Purpose: Iron deficiency anaemia (IDA) affects around 40% of < 5-year-olds globally. Unfortunately, IDA treatment by oral iron intervention often causes diarrhoea, thought to be linked to iron-induced changes in the gut microbiota. Piglets are valuable preclinical models for human infants since they share many physiological characteristics, have similar gut microbial populations and, if left untreated with iron, reliably develop IDA. We hypothesised that IDA and different forms of iron supplementation (oral and injection) would have differential effects on the gut microbiota that would consequently differentially impact immune and metabolic development during infancy. Methods: 24 one-day-old piglets were litter-matched into 4 treatment groups (n = 6): control (no iron); intramuscular iron (IM, 200mg Fe); oral iron (200mg FeSO ₄ /kg feed); IM+oral iron combined. Results: As expected, the iron-free treatment piglets developed IDA. This was combined with stunted growth and corresponding changes in plasma metabolites and immune parameters. However, although all 3 iron treatments prevented the development of IDA, piglets receiving oral iron were also stunted (compared to those which received IM iron; 14–19% weight-gain reduction over 27 days,  p Christensenella abundance provides novel evidence linking iron-induced stunting with Christensenella . Conclusion: The findings relayed here thus raise health concerns for infants receiving iron-fortified formula milk and/or those in LMICs enrolled in blanket oral iron supplementation programs.

Protein is an essential nutrient, but the detrimental effects of excess dietary protein on gut health are often overlooked. Protein fermentation by colonic microbiota may impair barrier function by increasing toxic metabolite production. We previously identified sex-by-protein interactions affecting the microbiota and its metabolites in vitro. Do sex-by-protein interactions in colonic protein fermentation lead to a sexually dimorphic response in gut barrier function in vivo? We hypothesised that high-protein diets would elicit sex-specific effects on microbiota and barrier function. Twenty sibling-matched male ( n = 10) and female ( n = 10) piglets were fed high-protein (28%) or standard-protein (SP; 18%) diets for four weeks. Bacterial populations were assessed using 16 S rRNA sequencing, urinary metabolites via SPME/GC-MS, and gut barrier proteins via quantitative fluorescence immunohistology. High-protein diets increased bacteria-derived p- cresol and reduced E-cadherin and CD45 + protein expression without altering microbiota composition. Females on high-protein diets had greater abundances of Staphylococcus and Chryseobacterium , elevated p- cresol, and reduced ZO-1 expression compared to males. High-protein diets appear to reduce barrier function and increase protein-associated toxic metabolite production in sexually dimorphic manners in pigs. If these results are replicated in humans, it indicates requirements for sex-specific nutritional strategies.

The composition and functionality of the gut microbiota (GM) changes throughout the life course. As we move into older age, it starts to shift towards a less healthy one, which may lead to an imbalance in the GM community. Strategies that can reverse age-related dysbiosis are an important part of healthy aging. Little is known about the GM composition of older adults with different physical activity (PA) levels and whether it might contribute to healthy ageing. The aim of this study was to compare the GM composition of older adults with different PA levels and assess if it is associated with healthy ageing. 101 participants aged between 65–85 years undertook anthropometric measures, a 6-min walking test, wore an accelerometer for 7 days and provided a faecal sample. Faecal GM composition was analysed using 16S rRNA sequencing. We found that those who fulfilled the WHO/UK PA recommendations had higher relative abundance of several health-related bacteria such as Lactobacillus, F. prausnitzii and Roseburia intestinalis and lower abundance of disease-associated bacteria such as D.piger or Enterobacterales when compared to those who did not reach PA recommendations. These findings suggest that PA might improve the GM composition and has the potential to, at least partially, revert age-associated dysbiosis and promote healthy ageing.

Anorexia nervosa (AN) is a psychiatric illness with harmful physical consequences. Studies have observed differences in the faecal microbiota of patients with AN compared to healthy controls. Diet has an impact on the gut microbiota, facilitating an altered community, such changes could impact the gut–brain axis. In this study, a three-stage gut model system that mimics the luminal microbiology of the large intestine was conducted to identify relationships between diet and gut microbiota. A microbial medium was developed to provide nutrients more appropriate to restricting subtype AN (R-AN). The model was inoculated with faeces and samples were taken to compare differences in the microbiota and end products following the fermentation of healthy control medium (HC) compared to R-AN medium. Then, 16S amplicon sequencing along with flow cytometry–fluorescence in situ hybridisation were used to ascertain changes in the microbiota. Gas chromatography (GC) was used to assess changes in microbial metabolites. There were reduced levels of SCFA following the fermentation of R-AN medium. The fermentation of R-AN media led to fewer total bacteria numbers, along with less bifidobacteria and Rumincoccus proximally, but more Clostridium and Enterobacteriaceae. Nutrient-deficient medium resulted in reduced neurotransmitter-producing bacteria, reduced butyrate-producing bacteria, and increased protein-utilising bacteria, all of which could be maintaining factors in AN. The model system provides a novel tool for exploring how extreme dietary changes impact the microbiota and could therefore could be useful for assessing appropriate gut–brain targeted treatments.

The relationship between the gut microbiota and cognitive health is complex and bidirectional, being significantly impacted by our diet. Evidence indicates that polyphenols and inulin can impact cognitive function via various mechanisms, one of which is the gut microbiota. In this study, effects of a wild blueberry treatment (WBB) and enriched chicory inulin powder were investigated both in vitro and in vivo. Gut microbiota composition and metabolites, including neurotransmitters, were assessed upon faecal microbial fermentation of WBB and inulin in a gut model system. Secondly, microbiota changes and cognitive function were assessed in children within a small pilot (n = 13) trial comparing WBB, inulin, and a maltodextrin placebo, via a series of tests measuring executive function and memory function, with faecal sampling at baseline, 4 weeks post-intervention and after a 4 week washout period. Both WBB and inulin led to microbial changes and increases in levels of short chain fatty acids in vitro. In vivo significant improvements in executive function and memory were observed following inulin and WBB consumption as compared to placebo. Cognitive benefits were accompanied by significant increases in Faecalibacterium prausnitzii in the inulin group, while in the WBB group, Bacteroidetes significantly increased and Firmicutes significantly decreased (p < 0.05). As such, WBB and inulin both impact the microbiota and may impact cognitive function via different gut-related or other mechanisms. This study highlights the important influence of diet on cognitive function that could, in part, be mediated by the gut microbiota.

Purpose: Impaired gut barrier function is associated with systemic inflammation and many chronic diseases. Undigested dietary proteins are fermented in the colon by the gut microbiota which produces nitrogenous metabolites shown to reduce barrier function in vitro. With growing evidence of sex-based differences in gut microbiotas, we determined whether there were sex by dietary protein interactions which could differentially impact barrier function via microbiota modification. Methods: Fermentation systems were inoculated with faeces from healthy males (n = 5) and females (n = 5) and supplemented with 0.9 g of non-hydrolysed proteins sourced from whey, fish, milk, soya, egg, pea, or mycoprotein. Microbial populations were quantified using fluorescence in situ hybridisation with flow cytometry. Metabolite concentrations were analysed using gas chromatography, solid phase microextraction coupled with gas chromatography-mass spectrometry and ELISA. Results: Increased protein availability resulted in increased proteolytic Bacteroides spp (p < 0.01) and Clostridium coccoides (p < 0.01), along with increased phenol (p < 0.01), p-cresol (p < 0.01), indole (p = 0.018) and ammonia (p < 0.01), varying by protein type. Counts of Clostridium cluster IX (p = 0.03) and concentration of p-cresol (p = 0.025) increased in males, while females produced more ammonia (p = 0.02), irrespective of protein type. Further, we observed significant sex-protein interactions affecting bacterial populations and metabolites (p < 0.005). Conclusions: Our findings suggest that protein fermentation by the gut microbiota in vitro is influenced by both protein source and the donor’s sex. Should these results be confirmed through human studies, they could have major implications for developing dietary recommendations tailored by sex to prevent chronic illnesses.

Probiotic supplements are increasingly being used to target the gut microbiome with a view to improving cognitive and psychological function via the gut-brain axis. One possible mechanism behind the effect of probiotics is through alterations to microbially-derived metabolites including short-chain fatty acids (SCFA) and neurotransmitters. However, research to date has largely been conducted in animal models or under conditions irrelevant to the human gastrointestinal tract (GIT). The aim of the current work was therefore to use anaerobic, pH controlled in vitro batch cultures to (a) assess the production of neuroactive metabolites in human faecal microbiota under conditions relevant to the human GIT, and (b) to explore how several pre-selected probiotic strains may affect bacterial composition and metabolite production. Enumeration of bacteria was assessed using fluorescence in situ hybridisation with flow cytometry, and concentrations of SCFAs and neurotransmitters were measured using gas chromatography and liquid chromatography mass spectroscopy, respectively. GABA, serotonin, tryptophan, and dopamine were successfully detected, suggesting some level of microbial derivation. The addition of Lactococcus lactis W58 and Lactobacillus rhamnosus W198 resulted in a significant increase in lactate after 8 h of fermentation, while no significant effect of probiotics on bacterial composition or neurotransmitter production was found.

Numerous health benefits have been reported from the consumption of cranberry-derived products, and recent studies have identified bioactive polysaccharides and oligosaccharides from cranberry pomace. This study aimed to further characterize xyloglucan and pectic oligosaccharide structures from pectinase-treated cranberry pomace and measure the growth and short-chain fatty acid production of 86 Lactobacillus strains using a cranberry oligosaccharide fraction as the carbon source. In addition to arabino-xyloglucan structures, cranberry oligosaccharides included pectic rhamnogalacturonan I which was methyl-esterified, acetylated and contained arabino-galacto-oligosaccharide side chains and a 4,5-unsaturated function at the non-reducing end. When grown on cranberry oligosaccharides, ten Lactobacillus strains reached a final culture density (ΔOD) ≥ 0.50 after 24 h incubation at 32 °C, which was comparable to L. plantarum ATCC BAA 793. All strains produced lactic, acetic, and propionic acids, and all but three strains produced butyric acid. This study demonstrated that the ability to metabolize cranberry oligosaccharides is Lactobacillus strain specific, with some strains having the potential to be probiotics, and for the first time showed these ten strains were capable of growth on this carbon source. The novel cranberry pectic and arabino-xyloglucan oligosaccharide structures reported here combined with the Lactobacillus strains that can metabolize cranberry oligosaccharides and produce short-chain fatty acids, have excellent potential as health-promoting synbiotics.

Swine respiratory disease is associated with productive losses. We evaluated the prevalence of lung lesions with an emphasis on Mycoplasma hyopneumoniae (Mh), porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV), as well as the impact on productive parameters in 108 finishing pigs at slaughter. Pathologic, immunohistochemical (IHC) and serologic analyses were performed. Pneumonic processes were observed in 73.1% of the animals. They mainly consisted of cranioventral bronchopneumonia (CBP) (46.3%) and pleuritis (17.6%). Microscopically, bronchointerstitial pneumonia (67.4%) was common and was occasionally combined (27.9%) with interstitial pneumonia (IP). Mh and PCV2-antigens were detected in bronchointerstitial pneumonia (70.7%) and IP cases (33.3%). There were low titers against Mh (18%) and high titers against PRRSV (100%) and PCV2 (65%). Animals with CBP remained at the farm longer; those with >10% of lung parenchyma involvement were sent later (208.8 days old) and had a lower average carcass weight (74.1 kg) and a lower daily weight gain (500.8 gr/day) compared with animals without lesions (567.2 gr/day, 77.7 kg, 200.8 days old). We suggest that animals that do not reach the weight at slaughter should be sent to slaughter regardless to avoid further negative impacts of respiratory disease in productive parameters.

Individuals with anorexia nervosa (AN) often suffer psychological and gastrointestinal problems consistent with a dysregulated gut microbial community. Psychobiotics have been postulated to modify microbiota and improve mental well-being and gut symptoms, but there is currently a lack of evidence for such approaches in AN. The aim of this study was to use an in vitro colonic model to evaluate the impact of dietary restrictions associated with AN on the intestinal ecosystem and to assess the impact of pre and probiotic intervention. Bacteriology was quantified using flow cytometry combined with fluorescence in situ hybridisation and metabolic end products (including neurotransmitters) by gas chromatography and liquid chromatography mass spectrometry Consistent with previous research, the nutritional changes significantly reduced total microbiota and metabolites compared with healthy conditions. Pre and probiotic supplementation on restricted conditions enhanced the microbial community and modulated metabolic activity to resemble that of a healthy diet. The model system indicates that nutritional changes associated with AN can impact the microbial community, and that these changes can, at least in part, be restored through the use of pre and probiotic interventions.