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Ferroptosis as a mediator of gut microbiota-driven inflammatory bowel disease: Evidence from genetic analyses.

Gut microbiota dysbiosis is increasingly recognized as a contributor to inflammatory bowel disease (IBD), yet causal relationships and underlying mechanisms remain unclear. Ferroptosis, an iron-dependent form of regulated cell death, plays a key role in epithelial barrier damage and inflammation. This study aimed to determine whether specific gut microbial taxa are causally associated with IBD and whether ferroptosis-related genes mediate this association using Mendelian randomization (MR). Two-sample MR and mediation MR analyses were performed using genome-wide association study summary data from the FinnGen consortium (IBD), the genome-wide association study catalog (473 gut microbial taxa), and the deCODE database (ferroptosis-related genes). Instrumental variables were selected with thresholds of P&#x2005;<&#x2005;1&#x2005;&#xd7;&#x2005;10-6 for microbes and P&#x2005;<&#x2005;5&#x2005;&#xd7;&#x2005;10-8 for traits, and linkage disequilibrium clumping (r2&#x2005;<&#x2005;0.001) was applied. Twenty-three microbial taxa showed significant causal associations with IBD (e.g., Chromatiales, OR&#x2005;=&#x2005;0.51; Acetobacterales, OR&#x2005;=&#x2005;2.61). Several ferroptosis-related genes were linked to IBD risk (e.g., GPX4, STAT3, IDO1). Mediation MR revealed that genes such as MUC1, IDO1, and ADAM23 partially mediated microbial effects on IBD, with mediation proportions up to 7.6%. This study provides novel genetic evidence supporting a gut microbiota-ferroptosis-IBD axis. Ferroptosis-related pathways may partially mediate microbial effects on IBD pathogenesis and represent promising targets for future therapeutic interventions.

Ferroptosis↗

Role of CD25hi CD45RA+ CD4 not Treg %T cell in mediating the effect of pyruvate fermentation to acetone on intrahepatic cholangiocarcinoma.

This study aimed to elucidate the potential correlation between gut microbiota and intrahepatic cholangiocarcinoma (ICC) by investigating their causal relationship, while also exploring the possible role of immune cells as mediators in this association. We first identified gut microbiota based on phylum, class, order, family, and genus level information. Using summary-level data from a Genome-Wide Association Study (GWAS), we performed a 2-sample Mendelian randomization (MR) analysis of ICC and gut microbiota. Furthermore, we used 2-step MR to quantify the proportion of the effect of immune cell-mediated gut microbiota on ICC. MR analysis identified pyruvate fermentation to acetone (PFA) as predicting ICC risk reduction. There was no strong evidence that genetically predicted ICC had an effect on PFA risk. Furthermore, the proportion of genetically predicted PFA mediated by CD25hi CD45RA+ CD4 not Treg %T cell (CCCTT) was 3% (95% CI: 0.93-5.03%). In conclusion, our study established a causal relationship between PFA and ICC. We observed that a minor fraction of this effect was mediated by CCCTT, while the majority of the impact exerted by PFA on ICC remains elusive. However, further investigations are warranted to elucidate the mechanisms underlying the influence of gut microbiota on ICC development.

Cholangiocarcinoma↗

Isolation by distance promotes strain diversification in the wild mouse gut microbiota.

Bacterial species within the mammalian gut microbiota exhibit considerable strain diversity associated with both geography and host genetic ancestry. However, because geography and host ancestry are typically confounded, disentangling their contributions to the diversification of gut bacterial strains has remained challenging. Here, we show through joint profiling of gut bacterial and mitochondrial genomes from wild-living populations of deer mice (Peromyscus maniculatus) sampled across the United States that isolation by distance (IBD) drives gut bacterial strain diversification independently of the effects of host ancestry. Analyses revealed significant IBD in 27 predominant gut bacterial species, including members of the Muribaculaceae and Lachnospiraceae, but limited evidence for co-inheritance of gut bacterial genomes with mitochondria during the diversification of extant mouse populations. Gut bacterial species capable of forming spores exhibited reduced IBD independently of phylogenetic history, indicating that adaptations facilitating bacterial dispersal can mitigate the geographic structuring of strain diversity. These results show that the diversification of gut bacterial strains within rodent species has been mediated by geographic separation of host populations rather than host genealogical divergence.

biogeography↗

Targeting the Microbiota-Gut-Brain Axis: Emerging Nanomedicine Approaches for Neurodegenerative Diseases.

The microbiota-gut-brain axis (MGBA) is a bidirectional relationship between the gut microbiota (GM) and the brain, where the GM affects the gastrointestinal tract (GIT) and the central nervous system (CNS), and vice versa. Microbiotas are important for several vital body processes, including metabolism, immunity, and homeostasis. The MGBA has three main pathways: the vagal nerve mechanism, the immune-related mechanism, and the neuroendocrine mechanism. GM imbalance, known as dysbiosis, affects the GIT, the brain, and the CNS. Furthermore, dysbiosis is linked to several neurological disorders such as Alzheimer's (AD), Parkinson's (PD), depression, autism spectrum disorder (ASD), and multiple sclerosis (MS). Studying MGBA gives researchers new therapeutic ideas using microbiota. Using special diets rich in fiber and probiotics, in addition to fecal microbiota transplantation (FMT), is being studied as a new therapy for MGBA. From the point of view that these therapeutic interventions maintain microbiota imbalance, which in turn will affect the brain and can relieve the neurological disorders caused by dysbiosis and MGBA.

Humans↗

Evaluation of metabolic, reproductive, and gut microbiota alterations in a comparative study of different preclinical models of polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a multifaceted, complex metabolic and endocrine disease where gut flora is considered an important factor in causing PCOS. This study aimed to identify a suitable PCOS model that contributes to gut microbial dysbiosis and metabolic and hormonal disturbances. Prepubertal SD rats were administered with normal control (NC), dihydrotestosterone (DHT), DHT with fructose (F), DHT+ high fat diet (HFD) for 91&#x2009;days, dehydroepiandrosterone (DHEA), DHEA with fructose, DHEA with HFD for 30&#x2009;days, sodium valproate (SV), sodium valproate with fructose, and sodium valproate with HFD for 21&#x2009;days. The estrous cycles were assessed over this timeframe. At the end of the experiment, superoxide dismutase and uterine and ovarian morphology were evaluated, along with hormone levels, lipid profiles, and 16S rRNA genomic sequencing. All models exhibited PCOS characteristics, including hormonal imbalances, insulin resistance (p&#x2009;&#x2264;&#x2009;.001), multiple follicular cysts on ultrasonography, and histological alterations. Gut microbial dysbiosis was observed across all PCOS-induced groups; however, the DHT alone group showed more pronounced alterations in microbial composition than the other experimental groups. Specifically, the DHT alone group exhibited reduced abundance of Firmicutes and increased abundance of Proteobacteria. Among the evaluated models, the DHT-only model showed more pronounced metabolic, hormonal, reproductive, and gut microbial alterations and may serve as a suitable model for PCOS research.

Animals↗

The Gfr Uptake System Provides a Context-Dependent Fitness Advantage to Salmonella Typhimurium SL1344 During the Initial Gut Colonization Phase.

Salmonella enterica serovar Typhimurium (S. Tm) is a major cause of foodborne diarrhea. However, in healthy individuals, the microbiota typically restricts the growth of incoming pathogens, a protective mechanism termed colonization resistance (CR). To circumvent CR, Salmonella strains can utilize private nutrients that remain untapped by the resident microbiota. However, the metabolic pathways and environmental niches promoting pathogen growth are still not completely understood. Here, we investigate the significance of the gfr operon in gut colonization of S. Tm, which is essential for the utilization of fructoselysine (FL) and glucoselysine (GL). These Amadori compounds are present in heated foods with high protein and carbohydrate contents. We detected FL in both mouse chow and the intestinal tract of mice and showed that gfr mutants are attenuated during the initial phase of colonization in the murine model. Experiments in gnotobiotic mice and competition experiments with Escherichia coli suggest that gfr-dependent fitness advantage is context-dependent. We conclude that dietary Amadori products like FL can support S. Tm gut colonization, depending on the metabolic capacities of the microbiota.

Salmonella typhimurium↗

Plant genetic and root-associated microbial diversity modulate Lactuca sativa responsiveness to a soil inoculum under phosphate deficiency.

Microbial-based approaches offer a promising strategy to decrease the use of chemical fertilizers in agriculture. Among them, arbuscular mycorrhizal fungi (AMF), which extend root surface area and enhance phosphate uptake, and phosphate-solubilizing bacteria (PSB) are particularly relevant. However, their effectiveness depends strongly on plant genetic diversity. To identify genetic markers underlying plant responses to beneficial soil microbes, we studied a panel of 128 fully sequenced Lactuca sativa varieties under controlled phosphate-starvation conditions and treated with AMF and PSB. Lettuce genetic variation showed a strong effect on physiological and morphological responses to microbial inoculation. Genome-wide association studies identified specific genomic regions associated with changes in leaf phosphate content and shoot biomass following treatment. Beyond genetic factors, we observed shifts in fungal &#x3b2;-diversity and increased bacterial &#x3b1;-diversity associated with phenotypic variation. We also identified 44 amplicon sequence variants associated with agriculturally relevant traits. Among these, six bacterial strains were experimentally validated through in vitro and pot experiments for their effects on leaf phosphate concentration and shoot biomass. Overall, we highlighted key genetic, microbial, and physiological mechanisms that may enhance microbial treatments for improved plant phosphate management in lettuce.

16S and ITS metabarcoding↗

Identification of gene targets regulated by the IclR-like regulator SL1344_3500 in Salmonella Typhimurium.

Transcriptional regulation of metabolic operons is important for optimal carbohydrate use and for mitigating the accumulation of toxic intermediates. Here, we characterize SL1344_3500, encoding a putative IclR-like regulator in Salmonella enterica Typhimurium. We present genetic and transcriptional evidence that it regulates the expression of two neighboring operons, one designated here as xynABC, enables utilization of xylonate as a sole carbon source. Furthermore, our findings indicate that SL1344_3500 is important for luminal growth in several mouse models, exerting its effects through the suppression of the xynABC operon. Based on the observation that the &#x394;SL1344_3500 deletion can be stably complemented in vivo, we developed a plasmid stabilization strategy. This gene complementation approach shows promise for generating stable gene reporters for long-term colonization experiments.IMPORTANCEUnderstanding transcriptional regulation in Salmonella enterica Typhimurium is crucial for revealing how enteric pathogens optimize metabolism to compete with commensals in the gut. SL1344_3500, an IclR-like transcriptional regulator controlling genes linked to sugar acid metabolism, is essential for luminal growth in mouse models through gene suppression and represents a potential target for antimicrobial development. Based on these observations, we developed stable reporter plasmids that use gene complementation of SL1344_3500 to prevent plasmid loss during long-term in vivo studies.

Salmonella typhimurium↗

Complete genome sequence of Streptococcus vaginalis strain UMB8616 isolated from the bladder of a female with urge urinary incontinence.

Streptococcus vaginalis is a recently identified bacterial species closely related to Streptococcus anginosus. It has been isolated from the human urogenital tract. We report the complete genome sequence of S. vaginalis UMB8616 (=ATCC TSD-371 = CCUG 77169 = DSM 115471) isolated from the bladder of a human female with urge urinary incontinence.

Streptococcus↗

Meta-CD: a metagenomic sequencing coverage and depth calculator for target species.

Metagenomic Coverage and Depth Calculator (Meta-CD) is a convenient, biologist-friendly tool for determining coverage and depth to enhance taxonomic detection, functional profiling, and metagenome-assembled genome (MAG) recovery in metagenomics. It supports experimental design and post-sequencing analysis, modeling how genome size, relative abundance, sequencing depth, and DNA quantity influence detection of target species.

metagenomics↗

Comparative metagenomic assessment of Illumina-compatible library preparation methods, short-read lengths, and PacBio HiFi sequencing reveals differences in microbial and functional diversity recovery from a complex environmental sample.

UNLABELLED: Metagenomics enables comprehensive exploration of microbial communities but is influenced by library preparation and sequencing technologies, affecting recovery of microbial genomes and proteins. Here, we benchmarked six Illumina-compatible short-read library preparation conditions in triplicate at 2 &#xd7; 150 bp and 2 &#xd7; 250 bp read lengths alongside PacBio HiFi long-read sequencing using a composite environmental sample of marine mangrove sediment and terrestrial palm tree soil. Longer short reads (2 &#xd7; 250 bp) combined with optimal library preparation approaches improved assembly quality, protein detection, and metagenome-assembled genome (MAG) recovery, achieving results approaching those of long-read sequencing. TruSeq libraries at 2 &#xd7; 250 bp recovered more than sevenfold more unique proteins than the same kit at 2 &#xd7; 150 bp (811,701 vs 110,108) using the same number of sequencing reads, while recovering a comparable number of high-quality MAGs to PacBio HiFi long-read sequencing (11 vs 18) and surpassing it in protein discovery by almost 10-fold (811,701 vs 87,745) at less than half of the sequencing cost. Furthermore, biosynthetic gene cluster analysis identified 46 biosynthetic gene clusters in TruSeq-250PE assemblies compared to 38 in PacBio HiFi, with several showing no close match in the MIBiG database. Although long reads yield more contiguity and complete genomes, longer short reads offer a cost-effective, scalable alternative for uncovering microbial and functional diversity. These findings provide critical guidance for metagenomic experimental design, demonstrating that strategic selection of library preparation chemistry and sequencing parameters can reveal more unknown microbial information in complex biomes without requiring additional sequencing depth. IMPORTANCE: Metagenomic outcomes are strongly influenced by library preparation and sequencing strategies, yet their combined effects in complex environmental samples remain poorly defined. Here, we provide the first direct comparison of Illumina NovaSeq short-read metagenomic sequencing at 2 &#xd7; 150 bp and 2 &#xd7; 250 bp across multiple library preparation kits, alongside PacBio HiFi long-read sequencing. We show that sequencing read length and library preparation critically shape assembly quality, protein recovery, and metagenome-assembled genome (MAG) reconstruction. These findings demonstrate that short-read sequencing at 2 &#xd7; 250 bp, with appropriate library preparation, can match long-read technologies in MAG recovery while substantially surpassing them in protein discovery. With less than half of the sequencing price and a 3.5-fold reduction in cost per gigabase of usable data, this method facilitates more accessible large-scale metagenomic analysis within complex environmental systems.

Metagenomics↗

Integrative analysis of rumen microbiota activity and host metabolism following methanogenesis inhibition in dairy cattle.

Enteric methane emission from dairy cattle is an environmental challenge. The most efficient mitigation strategies nowadays include the use of methanogenesis inhibitors that specifically target the rumen methanogens. Specific inhibitors, such as 3-nitrooxypropanol (3-NOP), reduce methane emissions without negative effects on the products of fermentation that serve as energy metabolites for the host. However, the concomitant effects of methanogenesis inhibition on rumen microbiota and host metabolism are poorly characterized. Thus, the objective of this study was to explore the association between rumen microbiota and host metabolism when methanogenesis is inhibited. Thirteen dairy cows were used as controls, and 12 were supplemented with 3-NOP for 6 weeks. Rumen microbiota composition and activity were characterized using metagenomics and metatranscriptomics. The host metabolism was assessed in a previous publication by a metabolomic analysis of the plasma. Microbiota data were used as explanatory variables of the metabolome data in a multiblock sparse partial least squares analysis. Overall, the association between rumen microbiota and host metabolism was moderate. Notwithstanding this, a few downregulated transcripts related to glycolysis, hydrogen transfer, and protein synthesis, together with a decrease in the proportion of taxa of the Oscillospirales order, showed a correlation with host one-carbon metabolites (|r| > 0.6). These associations raised novel hypotheses that remain to be elucidated, especially with regard to the effects of dihydrogen on the accumulation of microbial glycolysis and methanogenesis metabolite intermediates.IMPORTANCEDairy cattle produce a substantial amount of methane, a potent greenhouse gas. Several strategies have been designed to reduce methane production by targeting the rumen microbiota. One such strategy specifically inhibits methanogens with a molecule called 3-nitrooxypropanol. This study uses an integrative data analysis approach, combining rumen microbiota and host metabolome information, to explore the consequences of inhibiting methanogenesis on the holobiont. This provides additional holistic insight into the effect of methane mitigation strategies on dairy cattle.

Animals↗

Genomic and stress resistance characterization of Lactiplantibacillus plantarum GX17, a potential probiotic for animal feed applications.

UNLABELLED: Lactobacilli, recognized as beneficial bacteria within the human body, are celebrated for their multifaceted probiotic functions, including the regulation of intestinal flora, enhancement of body immunity, and promotion of nutrient absorption. This study comprehensively analyzed the genotypic and phenotypic characteristics of Lactiplantibacillus plantarum (L. plantarum) strains isolated from the intestines of healthy chicks and assessed their potential as probiotics. The assembled genome consists of 29,521,986 bp, and a total of 1,771 coding sequences (CDSs) were predicted. Based on the entire genome sequence analysis, 50 stress resistance genes and seven virulence factors were identified. The results of the phenotypic experiments showed that the strain had good resistance to high temperature, low temperature, acid, alkali, salt, artificial gastrointestinal fluid, and strong antioxidant capacity. Additionally, transcriptomic analysis confirmed that under stress conditions, the expression levels of key genes were significantly upregulated. Therefore, the phenotypic characteristics of L. plantarum GX17 align well with its genotypic features, demonstrating promising probiotic properties. This strain holds great potential as a probiotic candidate, and further investigation into its beneficial effects on human health is warranted. IMPORTANCE: In humans, Lactiplantibacillus plantarum may synergize with host microbiota to ameliorate dysbiosis-related pathologies, enhance immunomodulation, and facilitate micronutrient bioavailability. For livestock, its application could improve feed conversion ratios, suppress enteric pathogens through competitive exclusion, and mitigate antibiotic overuse, "a critical strategy in One Health frameworks." Further investigations into strain-specific mechanisms (e.g., postbiotic metabolites, quorum sensing regulation) are warranted to translate these genomic-phenotypic advantages into sustainable health solutions across species.

Probiotics↗

Interaction of host gene-gut microbiota in male grading of Macrobrachium rosenbergii.

UNLABELLED: The giant freshwater prawn (GFP; Macrobrachium rosenbergii), a crustacean of high nutritional and economic value, is crucial for aquaculture. During the same growth cycle, male GFPs develop into three distinct forms: small males, orange claw males, and blue claw males. These morphotypes display varying social behaviors, which severely constrain their industrial development. To address this, this study collected male GFP samples at critical developmental time points (100, 110, and 120 days post-hatching) for phenotypic trait measurement and analysis to obtain external morphological data. Through gut microbiota diversity analysis, we identified key gut bacteria (Lactococcus garvieae and Lactobacillus taiwanensis) influencing male morphotype differentiation. Transcriptomic analysis revealed host Kyoto Encyclopedia of Gene and Genome pathways and key genes (Wnt-6, CTSB, CTSL, PPAE, and TP53) associated with morphotype differentiation. The interactions among phenotypic traits, gut microbiota, and key genes were systematically studied through association analysis. Weighted gene co-expression network analysis was employed to construct co-expression modules, from which critical gene modules influencing phenotypic variation were identified. Through association network analysis, we established an "Achromobacter-CD-TRINITY_DN93139_c0_g2 (calpain clp-1)" interaction model. Our findings provide novel insights into the genetic enhancement of GFPs and offer guidelines for future research regarding gut symbiotic bacteria and breeding initiatives. IMPORTANCE: Male Macrobrachium rosenbergii (giant freshwater prawn [GFP]) in the same growth cycle will develop into small males, orange claw males, and blue claw males. This individual heterogeneity in growth significantly impacts the benefits of aquaculture. However, the factors influencing the differentiation of male GFP morphotype remain unclear. This study analyzed the phenotypic data of various GFP levels, the structure of the intestinal microbiota, and the differential genes within the gonadal transcriptome at critical time points of male GFP-level type differentiation. The aim was to explore the potential role of intestinal microbiota and differential genes in this phenomenon. This study offers new insights into the research on the phenomenon of male GFP-level type differentiation.

Animals↗

Exploring Potential Causality and Molecular Mechanisms between Heart Failure and Renal Failure: Insights from Mendelian Randomization Studies, the MIMIC-IV Database and the Gene Expression Omnibus Database.

UNLABELLED: Introduction: Heart failure (HF) and renal failure (RF) frequently coexist as cardiorenal syndrome, but their underlying causal mechanisms remain poorly defined. METHODS: This study applied Mendelian randomization (MR) using genome-wide association study (GWAS) datasets to investigate the causal effect of HF on RF. The inverse variance weighted method assessed causality, and summary-data-based MR (SMR) was used to identify therapeutic targets. Additional analyses included 211 gut microbiota traits and 1,400 serum metabolites. Validation was performed using the MIMIC-IV database. Transcriptomic data were analyzed to identify differentially expressed genes (DEGs) and key transcription factors (TFs). RESULTS: This study found that HF significantly increases the risk of RF (OR = 1.54, 95% CI: 1.07-2.23, p = 0.020). SMR analysis identified SURF1 and MAP3K11 as potential therapeutic targets for HF and RF. One gut microbiota genus and one serum metabolite showed causal associations with both diseases. MIMIC-IV data supported the HF-RF association (OR = 2.94, 95% CI: 2.81-3.07, p < 0.001). A total of 11 overlapping DEGs were enriched in the MAPK cascade, with RELA identified as a key TF. CONCLUSION: This study provides genetic and molecular evidence supporting a causal role of HF in RF, highlighting microbial, metabolic, and immune mechanisms as potential therapeutic targets. .

Humans↗

Urobiota analysis and genome-wide association study in pediatric recurrent urinary tract infections and vesicoureteral reflux.

Urinary tract infections (UTIs) are the most common severe bacterial infections in young children, often associated with vesicoureteral reflux (VUR). To explore host genetic-microbiota interactions and their clinical implications, we analyzed the urinary microbiota (urobiota) and conducted genome-wide association studies for bacterial abundance traits in pediatric patients with UTI and VUR from the Randomized Intervention for Children with Vesicoureteral Reflux and Careful Urinary Tract Infection Evaluation cohorts. We identified 4 urobiota community types based on relative abundance, characterized by the genera Enterococcus, Prevotella, Pseudomonas, and Escherichia/Shigella, and their associations with VUR, age, and toilet training. Children with VUR exhibited decreased microbial diversity and increased abundance of genera that included opportunistic pathogens, suggesting a disrupted urobiota. We detected genome-wide significant genetic associations with urinary bacterial relative abundances, in or near candidate genes including CXCL12, ABCC1, and ROBO1, which are implicated in urinary tract development and response to infection. We showed that Cxcl12 was induced 12 hours after uropathogenic bacterial infection in mouse bladder. The association with CXCL12 suggests a genetic link between UTI, VUR, and cardiovascular phenotypes later in life. These findings provide the first characterization to our knowledge of host genetic influences on the pediatric urobiota in UTI and VUR, offering insights into the interplay between disease, host genetics, and the urobiota composition.

Urinary Tract Infections↗