Background: Inflammatory bowel disease (IBD) arises from complex interactions among diet, host and gut microbiome. Although diet influences intestinal inflammation, the microbial and metabolic pathways involved, and their differences between Crohn’s disease (CD) and ulcerative colitis (UC), the two main subtypes of IBD remain unclear. Objective: To investigate how the gut microbiome mediates the effects of habitual diet on inflammatory activity in IBD. Design: This longitudinal study included 198 adults (100 healthy controls, 49 CD, 49 UC), participants completed a validated food frequency questionnaire. Dietary quality was evaluated using established indices (Alternative Mediterranean Diet, Healthy Eating Index-2015, Índice de Alimentación Saludable, Mean Adequacy Ratio, Plant-Based Dietary Indexes, Healthy Food Diversity). Participants also provided two stool samples (baseline and 6 months). Shotgun metagenomics (n=366) enabled taxonomic and functional profiling. Causal mediation analyses were used to identify microbial features mediating the effect of diet on inflammation. Results: IBD patients exhibited lower dietary diversity, fibre intake and nutritional adequacy compared with controls. Microbiome diversity was lowest in CD, intermediate in UC and correlated positively with higher intake of fibre, fruit, vegetables and nuts, and negative with processed foods and sugary beverages. Causal mediation analyses revealed that in CD, coffee, whole wheat bread and healthier diets lowered the Harvey-Bradshaw index through specific bacterial species and metabolites. In UC, Mediterranean-like diets, fruits and coffee reduced C reactive protein via greater microbial richness, reduced dysbiosis and short-chain fatty acid-related functions. Conclusion: Diet quality influences inflammation in IBD through distinct microbiome pathways: specific taxa and metabolites mediate effects in CD, whereas microbial richness and global composition drive protection in UC.

Diet is recognised as the main driver of changes in gut microbiota. However, linking habitual dietary intake to microbiome composition and activity remains a challenge, leaving most microbiome studies with little or no dietary information. To fill this knowledge gap, we conducted two consecutive studies (n = 84: a first pilot study (n = 40) to build a web-based, semi-quantitative simplified FFQ (sFFQ) based on three 24-h dietary recalls (24HRs); a second study (n = 44) served to validate the newly developed sFFQ using three 24HRs as reference method and to relate gut microbiome profiling (16S rRNA gene) with the extracted dietary and lifestyle data. Relative validation analysis provided acceptable classification and agreement for 13 out of 24 (54%) food groups and 20 out of 29 nutrients (69%) based on intraclass correlation coefficient, cross-classification, Spearman’s correlation, Wilcoxon test, and Bland–Altman. Microbiome analysis showed that higher diversity was positively associated with age, vaginal birth, and intake of fruit. In contrast, microbial diversity was negatively associated with BMI, processed meats, ready-to-eat meals, sodium, and saturated fat. Our analysis also revealed a correlation between food groups or nutrients and microbial composition. Overall, we provide the first dietary assessment tool to be validated and correlated with microbiome data for population studies.

Introduction: Our objective was to compare the vaginal microbiome in low‐risk and high‐risk pregnant women and to explore a potential association between vaginal microbiome and preterm birth.Material and methods: A pilot, consecutive, longitudinal, multicenter study was conducted in pregnant women at 18–22 weeks of gestation. Participants were assigned to one of three groups: control (normal cervix), pessary (cervical length ≤25 mm) and cerclage (cervical length ≤25 mm or history of preterm birth). Analysis and comparison of vaginal microbiota as a primary outcome was performed at inclusion and at 30 weeks of gestation, along with a follow‐up of pregnancy and perinatal outcomes. We assessed the vaginal microbiome of pregnant women presenting a short cervix with that of pregnant women having a normal cervix, and compared the vaginal microbiome of women with a short cervix before and after placement of a cervical pessary or a cervical cerclage.Results: The microbiome of our control cohort was dominated by Lactobacillus crispatus and inners. Five community state types were identified and microbiome diversity did not change significantly over 10 weeks in controls. On the other hand, a short cervix was associated with a lower microbial load and higher microbial richness, and was not correlated with Lactobacillus relative abundance. After intervention, the cerclage group (n = 19) had a significant increase in microbial richness and a shift towards community state types driven by various bacterial species, including Lactobacillus mulieris, unidentified Bifidobacterium or Enterococcus. These changes were not significantly observed in the pessary (n = 26) and control (n = 35) groups. The cerclage group had more threatened preterm labor episodes and poorer outcomes than the control and pessary groups.Conclusions: These findings indicate that a short cervix is associated with an altered vaginal microbiome community structure. The use of a cerclage for preterm birth prevention, as compared with a pessary, was associated with a microbial community harboring a relatively low abundance of Lactobacillus, with more threatened preterm labor episodes, and with poorer clinical outcomes.

Liver transplantation (LT) is crucial for end-stage liver disease, but it is linked to infection risks. Pathobionts, microorganisms potentially harmful under specific conditions, can cause complications post-transplant. Monitoring such pathogens in fecal samples can be challenging and therefore remains underexplored post-LT. This study aimed to analyze the gut microbiome before and after LT, tracking pathobionts and correlating clinical data. The study involved 17 liver transplant recipients, 17 healthy relatives (spouses), and 13 donors. Gut samples collected pre- and post-transplantation underwent bacterial and fungal profiling through DNA sequencing. Quantitative PCR was used to assess microbial load. Statistical analyses included alpha and beta diversity measures, differential abundance analysis, and correlation tests between microbiome and clinical parameters. Microbiome analysis revealed dynamic changes in diversity post-transplant. Notably, high-severity patients showed persistent and greater dysbiosis during the first months post-LT compared to low-severity patients, partly due to an antibiotic treatment pre-LT. The analysis identified a higher proportion of pathogens such as Escherichia coli/Shigella flexneri in high-severity cases post-transplant. Furthermore, butyrate producers including Roseburia intestinalis, Anaerostipes hadrus and Eubacterium coprostanoligenes were positively correlated with levels of albumin. This study offers valuable insights into post-LT microbiome changes, shedding light on the need for tailored prophylactic treatment post-LT.

Here, we examined the dynamics of the gut and respiratory microbiomes in severe COVID-19 patients in need of mechanical ventilation in the intensive care unit (ICU). We recruited 85 critically ill patients (53 with COVID-19 and 32 without COVID-19) and 17 healthy controls (HCs) and monitored them for up to 4 weeks. We analyzed the bacterial and fungal taxonomic profiles and loads of 232 gut and respiratory samples and we measured the blood levels of Interleukin 6, IgG, and IgM in COVID-19 patients. Upon ICU admission, the bacterial composition and load in the gut and respiratory samples were altered in critically ill patients compared with HCs. During their ICU stay, the patients experienced increased bacterial and fungal loads, drastic decreased bacterial richness, and progressive changes in bacterial and fungal taxonomic profiles. In the gut samples, six bacterial taxa could discriminate ICU-COV(+) from ICU-COV(−) cases upon ICU admission and the bacterial taxa were associated according to age, PaO2/FiO2, and CRP levels. In the respiratory samples of the ICU-COV(+) patients, bacterial signatures including Pseudomonas and Streptococcus were found to be correlated with the length of ICU stay. Our findings demonstrated that the gut and respiratory microbiome dysbiosis and bacterial signatures associated with critical illness emerged as biomarkers of COVID-19 severity and could be a potential predictor of ICU length of stay. We propose using a high-throughput sequencing approach as an alternative to traditional isolation techniques to monitor ICU patient infection.

The objective of this research was to evaluate the effects of different dietary fishmeal levels (30%, 15% and 0%) on growth, biometric parameters, nutritional efficiency, and intestinal health in juvenile European seabass. The replacement of fishmeal was made with a mixture of vegetable protein sources (soybean meal, wheat gluten, and wheat meal), and synthetic amino acids in isoproteic diets. The experimental period lasted 196 days, and the fish were fed the formulated diets twice a day, with an initial average weight of 40 g/fish. The results showed that it is possible to partially replace fishmeal with an inclusion level of 15% without compromising growth performance. However, the complete substitution of fishmeal resulted in increased viscerosomatic index (VSI) and mesenteric fat (MF), which was also associated with a pro-inflammatory response and moderate immunosuppression at the intestine level. Fish fed the 0 FM diet exhibited reduced growth, poor productive performance, and the lowest survival rates. Furthermore, the expression levels of Muc2 and β-actin genes, together with trends observed for TGF-β and IL-8, indicated impaired intestinal health and a pronounced immunosuppressive condition in these fish. Economic profitability was found to depend on the market prices of fishmeal and wheat gluten.