Akkermansia muciniphila gen. nov., sp. nov., a human intestinal mucin-degrading bacterium

Early life gut microbiome and its impact on childhood health and chronic conditions

The development of the gut microbiome is crucial to human health, particularly during the first three years of life. Given its role in immune development, disturbances in the establishment process of the gut microbiome may have long term consequences. This review summarizes evidence for these claims, highlighting compositional changes of the gut microbiome during this critical period of life as well as factors that affect gut microbiome development. Based on human and animal data, we conclude that the early-life microbiome is a determinant of long-term health, impacting physiological, metabolic, and immune processes. The early-life gut microbiome field faces challenges. Some of these challenges are technical, such as lack of standardized stool collection protocols, inconsistent DNA extraction methods, and outdated sequencing technologies. Other challenges are methodological: small sample sizes, lack of longitudinal studies, and poor control of confounding variables. To address these limitations, we advocate for more robust research methodologies to better understand the microbiome's role in health and disease. Improved methods will lead to more reliable microbiome studies and a deeper understanding of its impact on health outcomes.

Gut dysbiosis was inevitable, but tolerance was not: temporal responses of the murine microbiota that maintain its capacity for butyrate production correlate with sustained antinociception to chronic morphine

The therapeutic benefits of opioids are compromised by the development of analgesic tolerance, which necessitates higher dosing for pain management thereby increasing the liability for drug dependence and addiction. Rodent models indicate opposing roles of the gut microbiota in tolerance: morphine-induced gut dysbiosis exacerbates tolerance, whereas probiotics ameliorate tolerance. Not all individuals develop tolerance, which could be influenced by differences in microbiota, and yet no study design has capitalized upon this natural variation. We leveraged natural behavioral variation in a murine model of voluntary oral morphine self-administration to elucidate the mechanisms by which microbiota influences tolerance. Although all mice shared similar morphine-driven microbiota changes that largely masked informative associations with variability in tolerance, our high-resolution temporal analyses revealed a divergence in the progression of dysbiosis that best explained sustained antinociception. Mice that did not develop tolerance maintained a higher capacity for production of the short-chain fatty acid (SCFA) butyrate known to bolster intestinal barriers and promote neuronal homeostasis. Both fecal microbial transplantation (FMT) from donor mice that did not develop tolerance and dietary butyrate supplementation significantly reduced the development of tolerance independently of suppression of systemic inflammation. These findings could inform immediate therapies to extend the analgesic efficacy of opioids.

Akkermansia muciniphila reverses neuronal atrophy in Negr1 knockout mice with depression-like phenotypes

Genetic predispositions can shape the gut microbiome, which in turn modulates host gene expression and impacts host physiology. The complex interplay between host genetics and the gut microbiome likely contributes to the development of neuropsychiatric disorders, yet the mechanisms behind these interactions remain largely unexplored. In this study, we investigated the gut microbiota in Negr1 knockout (KO) mice, which exhibit anxiety- and depression-like behaviors, as NEGR1 (neuronal growth regulator 1) is a cell adhesion molecule linked to neuronal development and neuropsychiatric disorders. Our findings show significant early-life alterations in the gut microbiota composition of Negr1 KO mice, most notably a marked reduction in Akkermansia spp. along with reduced dendritic arborization and spine density in the nucleus accumbens (NAc) and the dentate gyrus (DG) of the hippocampus. Remarkably, daily administration of an Akkermansia strain isolated from wild-type mice reversed the neuronal structural abnormalities and ameliorated anxiety- and depression-like behaviors in Negr1 KO mice. Transcriptomic profiling revealed upregulation of mitochondrial genome-encoded genes in the NAc and hippocampus of Negr1 KO mice, along with a predisposition toward a pro-inflammatory state in the colon of Negr1 KO mice. The Akkermansia supplementation downregulated these mitochondrial genes in the NAc and hippocampus and upregulated genes involved in T cell activation and immune homeostasis in the colon. These findings demonstrate a novel gene-microbiome interaction in the pathophysiology of Negr1 KO mice, positioning Akkermansia spp. as a key mediator that improves neuronal atrophy and modulates anxiety- and depression-like behaviors. Our study provides compelling evidence for bidirectional interactions between host genetics and the gut microbiome in modulating neuropsychiatric phenotypes, offering new insights for addressing genetically influenced mental disorders.

Gut microbiota and associated metabolites: key players in high-fat diet-induced chronic diseases

Excessive intake of dietary fats is strongly associated with an increased risk of various chronic diseases, such as obesity, diabetes, hepatic metabolic disorders, cardiovascular disease, chronic intestinal inflammation, and certain cancers. A significant portion of the adverse effects of high-fat diet on disease risk is mediated through modifications in the gut microbiota. Specifically, high-fat diets are linked to reduced microbial diversity, an overgrowth of gram-negative bacteria, an elevated Firmicutes-to-Bacteroidetes ratio, and alterations at various taxonomic levels. These microbial alterations influence the intestinal metabolism of small molecules, which subsequently increases intestinal permeability, exacerbates inflammatory responses, disrupts metabolic functions, and impairs signal transduction pathways in the host. Consequently, diet-induced changes in the gut microbiota play a crucial role in the initiation and progression of chronic diseases. This review explores the relationship between high-fat diets and gut microbiota, highlighting their roles and underlying mechanisms in the development of chronic metabolic diseases. Additionally, we propose probiotic interventions may serve as a promising adjunctive therapy to counteract the negative effects of high-fat diet-induced alterations in gut microbiota composition.

Alterations of the gut commensal Akkermansia muciniphila in patients with COVID-19

Dysbiosis of gut microbiota is well established in coronavirus disease 2019 (COVID-19). While studies have attempted to establish a link between the gut commensal Akkermansia muciniphila (A. muciniphila) and COVID-19, the findings have been inconsistent and sometimes controversial. The intestinal microbial abundance information of COVID-19 patients was acquired and analysed from GMrepo database. Subsequently, A. muciniphila's metabolites, target-genes, and metabolite-target relationships was extracted from GutMGene database. Lastly, coronascape module in Metascape database is used for gene annotation and enrichment analysis in various host cells and tissues after SARS-CoV-2 infection. The results indicated that, in comparison to healthy people, A. muciniphila was significantly elevated in COVID-19 patients. This bacterium was found to be associated with heightened expression of IL-10, TLR2, TLR4, CLGN, CLDN4, TJP2, and TJP3, while concurrently experiencing a reduction in the expression of IL-12A and IL-12B in humans. The regulatory genes of A. muciniphila primarily enhance responses to viruses and cytokines, positively regulate cell migration, and control epithelial cell proliferation. Our study revealed a significant increase in the gut commensal A. muciniphila in COVID-19 patients. This bacterium can modulate host immune responses and may also serve as a probiotic with antiviral properties.

Akkermansia muciniphila restrains type 1 diabetes onset by eliciting cDC2 and Treg cell differentiation in NOD and STZ-induced experimental models

AIMS

Akkermansia muciniphila (A. muciniphila), a Gram-negative anaerobic mucus-layer-degrading bacterium found in the intestinal mucosa, exhibits potential as a probiotic, showing promise in mitigating autoimmune and chronic inflammatory diseases. This study aims to investigate whether A. muciniphila supplementation might confer protection against type 1 diabetes (T1D) and to elucidate the immunological pathways through which it exerts its beneficial effects.

MATERIALS AND METHODS

Non-obese diabetic (NOD) mice and streptozotocin (STZ)-induced type 1 diabetes (T1D) models were used to evaluate the protective effects of A. muciniphila during T1D course. Body weight, blood glucose levels, and T1D incidence were monitored. Immune responses in the pancreas, pancreatic (PLN) and cecal lymph nodes (CLN) and bone marrow-derived dendritic cells (BMDC) were evaluated by flow cytometry and ELISA.

KEY FINDINGS

Viable A. muciniphila supplementation conferred protection against T1D onset in STZ-induced T1D and NOD mouse models. T1D modulation by A. muciniphila in the STZ model was independent of the gut microbiota, and it was associated with increased tolerogenic type-2 dendritic cells (SIRP-α+CD11b+CD103+) and regulatory T (Treg) cells in PLN and pancreas. BMDC differentiated in the presence of A. muciniphila exhibited a tolerogenic profile and induced Treg cell generation in vitro. A. muciniphila-induced protection in T1D outcome was abrogated in FOXP3-DTR mice depleted of Treg cells, indicating that its mechanism of action is dependent on the CD4+Foxp3+ Treg cells.

SIGNIFICANCE

A. muciniphila supplementation attenuates T1D development in mice by modulating the tolerogenic immune response and is a promising new therapeutic tool for this autoimmune disease.

Integrative analyses of 16S rDNA sequencing and serum metabolomics demonstrate significant roles for the oral microbiota and serum metabolites in post-kidney transplant diabetes mellitus

Oral microbiota and serum metabolites play crucial roles in diabetes, but their relationship with post-transplant diabetes mellitus (PTDM), a common complication post-kidney transplantation, is not well characterized. This study investigated the relationship of oral microbiota and serum metabolites with PTDM using integrative analysis of 16S rDNA sequencing and serum metabolomics. We recruited 61 kidney transplant recipients, including 30 in the PTDM group and 31 in normal glucose tolerance controls. Oral samples and serum samples were collected from all the kidney transplant patients to perform 16S rDNA sequencing and serum metabolomics analysis. We annotated 689 oral microbial species, including 134 species unique to the PTDM group and 157 species unique to the control group. PTDM group showed upregulation of 36 metabolites and downregulation of 19 metabolites. Based on the random forest machine learning algorithm, genera such as UCG-005 (AUC = 0.9355), Succinivibrio (AUC = 0.8108); Akkermansia (AUC = 0.7742), Anaerovibrio (AUC = 0.2667), and Schwartzia (AUC = 0.2667), and serum metabolites such as LPI 18:0 (AUC: 0.8086), methylglyoxal (AUC: 0.7946), Vulgarin (AUC: 0.7828), 2-mercaptobenzothiazole (AUC: 0.7591), and PI(18:0/20:3(5Z,8Z,11Z)) (AUC: 0.7419) showed high diagnostic potential and may serve as clinical biomarkers. Furthermore, clinical indicators in PTDM patients, such as creatinine, cystatin C, and urea, showed a significant association with the differential oral microbiota and serum metabolites. Dysbiosis in the oral microbiota of the PTDM patients was associated with changes in the serum metabolites and alterations in their functions. These findings provide new insights toward identifying mechanisms by which oral microbiota and serum metabolites contribute to the development of PTDM.IMPORTANCEThis study reveals an imbalance in oral microbiota in patients with post-transplant diabetes and uncovers the potential relationship between oral microbiota and serum metabolites. These findings provide new insights into the role of oral microbiota and serum metabolites in the treatment of post-transplant diabetes, offering relevant biomarkers for clinicians and future research.

Alterations in Gut Microbiome Composition and Increased Inflammatory Markers in Post-COVID-19 Individuals

Dysfunctions in the immune system and alterations in the microbiome composition following SARS-CoV-2 infection contribute to persistent neurological issues observed in long COVID-19 survivors. We hypothesize that alterations in the gut microbiome composition and peripheral inflammatory profile following COVID-19 may play pivotal roles in behavior changes among individuals experiencing long-term illness. This cross-sectional study included a sample of post-COVID-19 and non-COVID-19 subjects. We assessed the presence of psychiatric conditions utilizing standardized diagnostic criteria, Hamilton Rating Scale for Anxiety (HAM-A), Hamilton Rating Scale for Depression (HAM-D), Biological Rhythms in Neuropsychiatry Assessment Interview (BRIAN), and Functional Assessment Short Test (FAST). Plasma samples were analyzed to examine lipid and inflammatory profiles. Fecal samples were evaluated by 16S rRNA sequencing to identify the gut microbiome composition. Noteworthy findings include a significant increase in the myeloid progenitor inhibitory factor 1 (MPIF-1), interleukin (IL)-17, and triglyceride among post-COVID-19 individuals. While α-diversity in the gut microbiome composition showed no significant differences, β-diversity demonstrated a notable distinction between the healthy control and post-COVID-19 groups. Post-COVID-19 individuals exhibited a decreased abundance of phylum, class, and order of Verrucomicrobia, family, and genus of Akkermansia, a short-chain fatty acid producer and microbial group significantly associated with intestinal barrier homeostasis and the amelioration of metabolic diseases. No difference was found between the behavioral and clinical data. In post-COVID-19 individuals, there were elevated IL-17 and MPIF-1 levels, compared to non-COVID-19 individuals. Additionally, there were notable alterations in gut microbiome composition, as evidenced by changes in β-diversity and a decrease of Verrucomicrobia, family, and Akkermansia genus abundance.

Safety evaluation of Akkermansia massiliensis sp. nov. DSM 33459

A novel strain of Akkermansia massiliensis sp. nov., designated as DSM 33459, was isolated from the feces of a healthy human donor. In order to fully assess the safety of this strain, following previously performed full genomic assessment, further in-vitro characterization and a combined in-vivo subchronic 28-day and 90-day toxicity study is reported herein. A. massiliensis DSM 33459 is tolerant to bile, somewhat tolerant to gastric juice pH conditions, and does not exhibit any aspects of virulence. This strain also demonstrates the ability to engraft the gastrointestinal tract of rats, persisting with continuous administration of the strain until the end of the study. Exposure to 2000 mg/kg BW/day A. massiliensis DSM 33459 did not produce any evidence of toxicity after either 28- or 90-days of exposure and did not translocate across the gastrointestinal barrier. Therefore, the NOEL for A. massiliensis DSM 33459, administered for 28- or 90-days, was determined to be the limit dose at 2000 mg/kg/day in male and female rats, a level which meets or exceeds calculated dose equivalent of 5.62 × 1011 CFU/kg/day.

Gut Microbiome Interventions: From Dysbiosis to Next-Generation Probiotics (NGPs) for Disease Management

The gut microbiome, sometimes referred to as the "second brain," the "lost organ," the "identification card of the individual," and the "fingerprint of the host," possesses diverse traits and functions that influence health. The impact of gut commensal bacteria on health, as opposed to environmental pathogenic factors, has generated increasing interest in recent years, culminating in a substantial body of study. Research indicates that dysbiosis of the intestinal microbiota is commonly observed in chronic inflammatory diseases, including colitis, obesity/metabolic syndrome, diabetes mellitus, liver infections, allergic conditions, cardiovascular diseases, COVID-19, cancers, and neurodegenerative disorders. The International Scientific Association for Probiotics and Prebiotics has recently refined the theory of complementary and synergistic synbiotics. In recent years, the field of microbiome research has been significantly advanced by technological developments such as massive culturomics, gnotobiotics, metabolomics, parallel DNA sequencing, and RNA sequencing. This review article examined the potential next generation probiotics (NGPs) and explored some of them, Faecalibacterium prausnitzii, Bacteroides thetaiotaomicron, Akkermansia muciniphila, Parabacteroides goldsteinii, Bacteroides fragilis, Eubacterium hallii, Roseburia intestinalis, Christensenella minuta, Prevotella copri, and Oscillospira guilliermondii. In addition to these useful probiotic strains, psychobiotics, members of the families of Lactobacilli, Streptococci, Bifidobacteria, Escherichia, and Enterococci, have extended applicability in the use for neurodevelopmental and neurodegenerative disorders. The article also reviewed current trends and limitations in NGPs to enhance our comprehensive understanding of key concepts associated with the consumption of probiotics and proposed necessary initiatives for researchers to engage in collaborative translational research as future therapeutic solutions.

Intermittent fasting and metabolic dysfunction-associated steatotic liver disease: the potential role of the gut-liver axis

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing public health concern linked to the increasing prevalence of metabolic syndrome, including obesity and type 2 diabetes (T2D). MASLD remains a significant clinical challenge due to the absence of effective therapeutic interventions. Intermittent fasting (IF) has emerged as a promising non-pharmacological strategy for managing MASLD. Although the exact mechanisms underpinning the possible beneficial effects of IF on MASLD are not yet fully elucidated, the gut microbiota and its metabolic byproducts are increasingly recognized as potential mediators of these effects. The gut-liver axis may act as an important conduit through which IF exerts its beneficial influence on hepatic function. This review comprehensively examines the impact of various IF protocols on gut microbiota composition, investigating the resultant alterations in microbial diversity and metabolomic profiles, and their potential implications for liver health and the improvement of MASLD.

Probiotics may not adhere to gut and provide benefits in inflammatory bowel disease patients based on an AOM/DSS murine model

BACKGROUND

Dysbiosis, characterized by imbalanced gut microbiota, is common in patients with inflammatory bowel disease (IBD) and colitis-associated colorectal cancer (CAC). While probiotics theoretically offer promise for IBD treatment, their actual efficacy remains uncertain, leading to non-recommendation in current guidelines. Akkermansia muciniphila (AKK) is a potential next-generation probiotic strain with benefits in obesity, diabetes and gut protection. Recent study showed reduced AKK abundance in IBD patients and mice with colitis and CAC. Hence, we administered AKK treatment to these mice to assess its effects.

METHODS

Using a mouse model of colitis and CAC induced by azoxymethane/dextran sodium sulfate (AOM/DSS) in BALB/c mice, we administered AKK orally to mice on the AOM/DSS protocol with 5 × 108 CFU of AKK three times a week for a total 27 times. The treatment effect of AKK were evaluated.

RESULTS

Despite AKK supplementation, mice showed no significant differences in body weight, colon length, histological inflammation, or short chain fatty acid composition compared to those on the AOM/DSS protocol alone. Unexpectedly, AKK-treated mice exhibited decreased AKK abundance in stool samples, suggesting poor adherence and colonization despite supplementation. These results parallel our previous findings with Clotridium butyricum, indicating challenges in probiotic intervention for severe colitis and CAC due to mucosal barrier damage.

CONCLUSION

Our study highlights the limitations of probiotic therapy in IBD, attributing its failure to inadequate adherence and colonization in damaged mucosal barriers. Further research is warranted to clarify the role of probiotics in IBD management.

New Horizons of Astaxanthin-loaded Akkermansia muciniphila as an Integrated Dietary Supplement: Physicochemical Structures and Gastrointestinal Fate

Astaxanthin (ASX) gains wide interest in food and nutritional sciences due to its great antioxidant and anti-inflammatory properties. However, ASX faces challenges such as poor water solubility, low bioavailability, and sensitivity to environmental factors. In this study, we employ Akkermansia muciniphila (AKK) with mucoadhesive property as a carrier for ASX to enhance ASX stability and bioaccessibility. The complex multilayered cell envelope of AKK cell provided space for ASX loading. Immersion loading yielded the highest ASX encapsulation efficiency (10.80 ± 2.29 μg/mg in ASX@AKK group and 11.47 ± 3.52 μg/mg in ASX@AKK-Heat group), whereas osmoporation loading and vacuum loading yielded ASX encapsulation efficiencies of 4-6 μg/mg. The encapsulated ASX demonstrated improved thermostability, tolerating pasteurization, and was predominantly amorphous in state, interacting with AKK primarily through hydrophobic interactions and partial hydrogen bonding interactions. The ASX@AKK system facilitated precise ASX release in the intestine and markedly enhanced bioaccessibility, increasing approximately 25.7-fold in simulated intestinal fluid and 77.6-fold in simulated colonic fluid. Importantly, ASX encapsulation did not impair AKK's adhesive affinity to mucus. Therefore, the newly developed integrated dietary supplements have both the functional activity of inactivated AKK as a postbiotic and the antioxidant property of the intestine-targeted released ASX, showing dual-functional activities. These findings highlight a paradigm shift in the functional application of probiotics, showcasing their potential as innovative vehicles for targeted nutrient delivery with improved bioaccessibility and synergistic health effects.

Maternal gut microbiota influences immune activation at the maternal-fetal interface affecting pregnancy outcome

Preeclampsia is a leading cause of morbidity and mortality in pregnant women, affecting 5-8% of gestations worldwide. Its development is influenced by maternal immune abnormalities, metabolic disorders, and gut dysbiosis. In this study, we show that gut dysbiosis in pregnant C57BL/6J dams leads to increased fetal resorption, impaired placental development and altered vascularization. These adverse outcomes are associated with key pathological features of preeclampsia, including hypoxia, endoplasmic reticulum (ER) stress and reduction in uterine natural killer (NK) cell numbers. Furthermore, gut dysbiosis significantly perturbs placental carbohydrate metabolism, which impairs NK cell IFN-γ secretion. Notably, glucose supplementation restores placental NK cell function and reduces fetal resorption, suggesting that the observed impairment is reversible and dependent on a lower glycolytic rate. These findings highlight maternal gut microbiota as a key player in carbohydrate metabolism, with a pivotal role in modulating placental immunity and pregnancy outcome. The results provide valuable insights into potential metabolic biomarkers and suggest that targeting the gut microbiota may offer a strategy for preventing preeclampsia.

A single-cell transcriptomic atlas of all cell types in the brain of 5xFAD Alzheimer mice in response to dietary inulin supplementation

BACKGROUND

Alzheimer's disease (AD) is a progressive neurodegenerative disease that is a major threat to the aging population. Due to lack of effective therapy, preventive treatments are important strategies to limit AD onset and progression, of which dietary regimes have been implicated as a key factor. Diet with high fiber content is known to have beneficial effects on cognitive decline in AD. However, a global survey on microbiome and brain cell dynamics in response to high fiber intake at single-cell resolution in AD mouse models is still missing.

RESULTS

Here, we show that dietary inulin supplementation synergized with AD progression to specifically increase the abundance of Akkermansia muciniphila in gut microbiome of 5 × Familial AD (FAD) mice. By performing single-nucleus RNA sequencing on different regions of the whole brain with three independent biological replicates, we reveal region-specific changes in the proportion of neuron, astrocyte, and granule cell subpopulations upon inulin supplementation in 5xFAD mice. In addition, we find that astrocytes have more pronounced region-specific diversity than microglia. Intriguingly, such dietary change reduces amyloid-β plaque burden and alleviates microgliosis in the forebrain region, without affecting the spatial learning and memory.

CONCLUSIONS

These results provide a comprehensive overview on the transcriptomic changes in individual cells of the entire mouse brain in response to high fiber intake and a resourceful foundation for future mechanistic studies on the influence of diet and gut microbiome on the brain during neurodegeneration.

The multifaceted roles of Akkermansia muciniphila in neurological disorders

Gut commensals regulate neurological disorders through dynamic bidirectional communication along the gut-brain axis. Recent evidence has highlighted the well-documented beneficial role of the commensal gut bacterium Akkermansia muciniphila and its components in promoting host health. However, numerous clinical studies have demonstrated a paradoxical role of A. muciniphila in individuals with various neurological conditions. In this opinion article, we review the correlation between the prevalence of this gut commensal and the development of several disorders, including stroke, multiple sclerosis (MS), Parkinson's disease (PD), and Alzheimer's disease (AD). We focus on the potential mechanisms by which A. muciniphila may contribute to these diseases. An in-depth understanding of these correlations and the underlying pathogenic mechanisms could shed new light on the mechanisms of disease pathogenesis and provide a logical rationale for developing new therapies for these neurological conditions.

HiBC: a publicly available collection of bacterial strains isolated from the human gut

Numerous bacteria in the human gut microbiome remain unknown and/or have yet to be cultured. While collections of human gut bacteria have been published, few strains are accessible to the scientific community. We have therefore created a publicly available collection of bacterial strains isolated from the human gut. The Human intestinal Bacteria Collection (HiBC) ( https://www.hibc.rwth-aachen.de ) contains 340 strains representing 198 species within 29 families and 7 phyla, of which 29 previously unknown species are taxonomically described and named. These included two butyrate-producing species of Faecalibacterium and new dominant species associated with health and inflammatory bowel disease, Ruminococcoides intestinale and Blautia intestinihominis, respectively. Plasmids were prolific within the HiBC isolates, with almost half (46%) of strains containing plasmids, with a maximum of six within a strain. This included a broadly occurring plasmid (pBAC) that exists in three diverse forms across Bacteroidales species. Megaplasmids were identified within two strains, the pMMCAT megaplasmid is globally present within multiple Bacteroidales species. This collection of easily searchable and publicly available gut bacterial isolates will facilitate functional studies of the gut microbiome.

Structure-function studies on drug-reactivating β-glucuronidase from mucin-degrading gut symbiont Akkermansia muciniphila

Gut microbial β-glucuronidases (mGUS) not only regulate several hormones and neurotransmitters, they also impact the efficacy and toxicity of xenobiotics. On certain anticancer drugs, e.g. irinotecan (SN-38), mGUS activity leads to enterohepatic recirculation resulting into severe diarrhea. Here, we report the expression, purification and characterization of AmGUS, a novel β-glucuronidase from Akkermansia muciniphila. A. muciniphila is a prominent gut symbiont with beneficial effects on metabolic health and gut homeostasis. AmGUS demonstrates specificity towards glucuronide substrates with no glucosidase or galactosidase activity. Interestingly, it also shows efficient cleavage of the glucuronidated form of the anti-cancer drug, SN38, potentially leading to its enterohepatic recirculation. Furthermore, we find that AmGUS functions as a monomer, contrary to other GUS enzymes that exist as oligomers. mGUS are classified into distinct loop-types based on different active site loops around a conserved core providing substrate specificity. Computational modeling of AmGUS structure reveals that it belongs to the mL2 loop-type GUS enzymes, despite sharing significant sequence/structural similarity with the mL1 loop-type and NL-type GUSs. Interestingly, AmGUS also has a unique N-terminal loop previously not observed in any other GUS enzyme possibly aiding in the processing of drug-glucuronides. Together, these findings suggest that GUS from A. muciniphila belongs to a new class of GUS enzymes with unique active site loop structures. The presence of this unique GUS enzyme may help A. muciniphila in colonizing the human gut. Overall, this study broadens our knowledge of the structural and functional understanding of GUSome in the human gut microbiome.

Loperamide increases mouse gut transit time in a dose-dependent manner with treatment duration-dependent effects on distinct gut microbial taxa

Intestinal transit time has been recognized as an important factor in shaping the gut microbiota, although causality remains to be firmly demonstrated. The aim of this study was to evaluate the effect of different loperamide doses on the mouse intestinal transit time and to investigate the effects of increasing transit time on the gut microbial community. Loperamide significantly increased the transit time in a dose-dependent manner. Additionally, we observed a significant difference between the control group and the loperamide-treated groups in the abundance of the bacterial families Bacteroidaceae, Erysipelotrichaceae, Porphyromonadaceae, and Akkermansiaceae after 7 days of loperamide treatment, with the bacterial families responding to the increased transit time at different rates. Fermentation of faeces obtained from the same mice, with or without loperamide, demonstrated that the observed effects on gut microbiota in vivo were not a result of direct interactions between loperamide and the gut microbiota but rather a consequence of loperamide-induced increased intestinal transit time. In the cecum of the mice, we found higher levels of propionate in the high-dose group compared to the control and low-dose groups. Collectively, our findings establish that an altered transit time is causal to changes in the composition and activity of the microbiome.

Function and therapeutic potential of Amuc_1100, an outer membrane protein of Akkermansia muciniphila: A review

The gut microbiota-derived protein Amuc_1100, a key outer membrane component of Akkermansia muciniphila, has emerged as a groundbreaking therapeutic agent with unique structural and functional properties. Amuc_1100 exerts multifaceted immune-metabolic effects through novel mechanisms, including modulation of TLR2/4 and JAK/STAT pathways. This review highlights its unique multi-component structure that enables synergistic biological activity, and its pharmacological properties, which underlies its ability to enhance intestinal barrier integrity, restore microbiota balance, and suppress systemic inflammation. Crucially, Amuc_1100 demonstrates unprecedented therapeutic versatility across both intestinal disorders (e.g., inflammatory bowel disease, antibiotic-associated diarrhea) and extraintestinal conditions-notably improving neuropsychiatric symptoms via gut-serotonin axis regulation, combating cancer through CD8+ T cell activation, and mitigating cardiotoxicity via gut-heart immune crosstalk. Emerging innovations in targeted delivery systems, including gut-retentive nano-formulations and engineered probiotic vectors, further amplify its clinical potential. We critically evaluate recent advances distinguishing Amuc_1100's mechanisms from live bacterial interventions. By synthesizing evidence from preclinical models, this work positions Amuc_1100 as a prototype for next-generation microbiome-derived therapeutics, bridging microbial ecology with precision medicine.

Peptidoglycan isolated from the fruit of Lycium barbarum alleviates liver fibrosis in mice by regulating the TGF-β/Smad7 signaling and gut microbiota

The hepatoprotective effect of the fruit of Lycium barbarum has been documented in China over millennia. Lycium barbarum polysaccharides (LBPs) were the first macromolecules reported to mitigate liver fibrosis in carbon tetrachloride (CCl4)-treated mice. Herein, a neutral peptidoglycan, named as LBPW, was extracted from the fruit of Lycium barbarum. In this study, we investigated the hepatoprotective mechanisms of LBPW. CCl4-induced liver fibrosis mice were administered LBPW (50, 100, 200 mg ·kg-1 ·d-1, i.p.) or (100, 200, 300 mg· kg-1 ·d-1, i.g.) for 6 weeks. We showed that either i.p. or i.g. administration of LBPW dose-dependently attenuated liver damage and fibrosis in CCl4-treated mice. Pharmacokinetic analysis showed that cyanine 5.5 amine (Cy5.5)-labeled LBPW (Cy5.5-LBPW) could be detected in the liver through i.p. and i.g. administration with i.g.-administered Cy5.5-LBPW mainly accumulating in the intestine. In TGF-β1-stimulated LX-2 cells as well as in the liver of CCl4-treated mice, we demonstrated that LBPW significantly upregulated Smad7, a negative regulator of TGF-β/Smad signaling, to retard the activation of hepatic stellate cells (HSCs) and prevent liver fibrosis. On the other hand, LBPW significantly boosted the abundance of Akkermansia muciniphila (A. muciniphila) and fortified gut barrier function. We demonstrated that A. muciniphila might be responsible for the efficacy of LBPW since decreasing the abundance of this bacterium by antibiotics (Abs) blocked the effectiveness of LBPW. Overall, our results show that LBPW may exert the hepatoprotective effect via rebalancing TGF-β/Smad7 signaling and propagating gut commensal A. muciniphila, suggesting that LBPW could be leading components to be developed as new drug candidates or nutraceuticals against liver fibrosis.

The Impact of Diet on the Colonization of Beneficial Microbes from an Ecological Perspective

With growing recognition of the pivotal role of gut microbiota in human health, probiotics have gained widespread attention for their potential to restore microbial homeostasis. However, a critical challenge persists: limited colonization efficiency among most probiotic strains compromises their therapeutic efficacy. This overview synthesizes ecological principles with cutting-edge microbiome research to elucidate the dynamic interplay between dietary components and probiotic colonization within the intestinal niche. This overview systematically analyzes: (1) stage-specific colonization mechanisms spanning microbial introduction, establishment, and proliferation; (2) nutrient-driven modulation of gut microbiota composition and function; and (3) the dual role of common dietary patterns as both facilitators and disruptors of probiotic persistence. Notably, this overview identifies key dietary strategies, including precision delivery of prebiotic fibers and polyphenol-microbiota crosstalk, that enhance niche adaptation through pH optimization, adhesion potentiation, and competitive exclusion of pathogens. Furthermore, this overview critically evaluates current limitations in probiotic research, particularly strain-specific variability and methodological constraints in simulating host-microbe-diet tripartite interactions. To bridge these gaps, this overview proposes an interdisciplinary framework integrating omics-driven strain selection, engineered delivery systems, and personalized nutrition models. Collectively, this work advances a mechanistic understanding of diet-microbiota interactions while providing actionable insights for developing targeted probiotic therapies and evidence-based dietary interventions to optimize gut ecosystem resilience.

The Role of Beneficial Microbiota in COVID-19: Insights from Key Bacterial Genera

The COVID-19 pandemic has highlighted the need for a comprehensive understanding of the factors influencing disease severity and progression. Emerging research indicates that the human microbiota, particularly beneficial bacteria, significantly impacts immune responses and health outcomes in COVID-19 patients. While existing studies provide general insights into the relationship between the microbiota and probiotics with COVID-19, they often lack a detailed exploration of how specific bacterial taxa might be used as adjunctive treatments. This review aims to address this gap by focusing on ten key genera of beneficial bacteria, discussing their roles in COVID-19 and evaluating their potential as probiotics for prevention and treatment. The review covers the impact of these microbes on human health, their population alterations in COVID-19 patients, and their interactions with other viral infections. Among these microbes, several exhibit distinct patterns of abundance in COVID-19 patients, influencing disease outcomes and highlighting their potential roles in infection dynamics. In COVID-19 patients, populations of Akkermansia, Ruminococcus, and Roseburia are consistently reduced, while those of Faecalibacterium show a significant decline in more severe cases. Bacteroides presents varying effects depending on the species involved. Alterations in the abundance of Blautia and Lachnospiraceae are associated with increased inflammation and disease severity. Likewise, the depletion of Lachnospira and Coprococcus populations, both linked to anti-inflammatory effects, may exacerbate symptom severity. Oscillospira, though less studied, is connected to overall health and could have implications for viral infections. This review synthesizes the current understanding of these beneficial microbes to highlight the importance of maintaining a healthy microbiota to alleviate the impact of COVID-19 and contribute to the development of novel therapeutic strategies involving microbiota modulation.

Enteromorpha prolifera soluble dietary fiber alleviates ulcerative colitis through restoration of mucosal barrier and gut microbiota homeostasis

Background

Ulcerative colitis (UC), a recurrent chronic colon inflammation, presents substantial therapeutic challenges due to the frequent adverse effects associated with conventional pharmacological treatments. These limitations underscore the critical need for developing alternative dietary interventions with improved safety profiles. The present study investigated the therapeutic potential of Enteromorpha prolifera soluble dietary fiber microparticles (EDFM) in UC management, focusing on restoring mucosal barrier integrity and modulating gut microbiota homeostasis.

Methods

EDFM was fabricated through aqueous extraction of E. prolifera soluble dietary fiber via boiling followed by spray-drying. A mouse UC model was induced by dextran sulfate sodium (DSS). The severity of UC was evaluated through daily disease activity index (DAI) scoring; quantification of pro-inflammatory cytokines (TNF-α, IL-1β) via ELISA; histopathological analysis of colon sections with H&E staining; immunofluorescence detection of tight junction proteins (ZO-1, occludin); and 16S rRNA sequencing for gut microbiota.

Results

EDFM treatment significantly reduced the expression of pro-inflammatory cytokines (TNF-α and IL-1β), enhanced the expression of tight junction proteins (ZO-1 and occludin), and stimulated mucin (MUC2) production. Additionally, EDFM promoted the proliferation of beneficial probiotics (Alloprevotella, Lachnospiraceae_NK4A136_group, and Ruminococcaceae_UCG-014), while inhibiting pathogenic bacteria (Escherichia-Shigella, Parabacteroides, Rikenellaceae_RC9_gut_group, Odoribacter, and [Ruminococcus]_torques_group).

Conclusion

EDFM supplementation significantly ameliorates UC through dual modulation of gut microbiota and intestinal barrier integrity, indicating its potential as a functional food ingredient for UC prevention and treatment.

Bibliometric analysis of research trends and prospective directions of Akkermansia muciniphila from 2010 to 2024

Background

Akkermansia muciniphila (A. muciniphila) is an emerging probiotic with potential impact on human health, and there is a growing interest in this area, but an overall analysis of research trends is lacking. This study conducted a detailed bibliometric analysis and visualization of A. muciniphila research to examine the current research status, hotspots, and trends, aiming to inform future research directions.

Methods

This study utilized the Web of Science database to search research on A. muciniphila from 2010 to 2024. Bibliometric analysis was conducted using CiteSpace and VOSviewer software to generate yearly publication trends, contributions by countries, institutions, and distinguished researchers, as well as key themes and influential researches. This analysis aimed to visualize and explore the literature over the past 15 years, guiding future researches and identifying gaps in the field of intestinal flora in A. muciniphila.

Results

We searched a total of 4,423 related publications. Wei Chen, Willem de Vos and Patrice D. Cani are the primary contributors to A. muciniphila 's research. The top contributing countries and institutions are China, the United States, South Korea, Spain, and Italy, with research centers such as the Chinese Academy of Sciences, Zhejiang University, the University of Copenhagen, and the University of Helsinki being the main contributors. Current research hotspots focus on the molecular biology of A. muciniphila, such as its role in intestinal barrier maintenance, immune response, and its potential for regulating and treating digestive and metabolic diseases, such as cancer, fatty liver disease, inflammatory bowel disease, etc., through bile acid metabolism, extracellular vesicles, and insulin resistance.

Conclusion

Our study synthesizes current research on A. muciniphila in various disease areas and suggests enhancing collaboration among countries, institutions, and authors to advance A. muciniphila-related clinical and basic research, explore its efficacy in a variety of diseases and the effects of commonly used clinical medications on A. muciniphila, to fill the research gaps in the current field, and to provide valid evidence for the development of A. muciniphila as a novel probiotic supplement.

Akkermansia muciniphila protects against dopamine neurotoxicity by modulating butyrate to inhibit microglia-mediated neuroinflammation

Parkinson's disease (PD) is an age-related and second most common neurodegenerative disease. To date, safe and efficient therapeutic drugs are deficient. In recent years, the relationship between gut microbiota and CNS have received more attention. Homeostatic imbalance of gut microbiota was revealed to participate in the progression of PD. This study detected that Akkermansia muciniphila (A. muciniphila) was apparently decreased in the feces of PD rats via 16S rRNA amplicon sequencing. Furtherly, we found that exogenous supplementation of A. muciniphila could improve 6-OHDA-induced motor dysfunction and dopamine (DA) neuronal damage and neuroinflammatory factors release in PD rats. Moreover, the short-chain fatty acids (SCFAs) sequencing demonstrated that A. muciniphila addition increased butyrate content both in gut and brain. The subsequent functional experiments confirmed that the exogenous supplementation of butyrate conferred neuroprotection against DA neurotoxicity. Mechanically, butyrate targeted microglia to attenuate DA neuronal injury via inhibiting microglia activation and neuroinflammatory factors production. In conclusion, A. muciniphila protected DA neuronal damage by modulating butyrate to inhibit microglia-elicited neuroinflammation. These findings provided a potential application of A. muciniphila on PD treatment.

Machine learning determines the incidence of Alzheimer's disease based on population gut microbiome profile

The human microbiome is a complex and dynamic community of microbes, thought to have symbiotic benefit to its host. Influences of the gut microbiome on brain microglia have been identified as a potential mechanism contributing to neurodegenerative diseases, such as Alzheimer's disease, motor neurone disease and Parkinson's disease (Boddy SL, Giovannelli I, Sassani M, et al. The gut microbiome: A key player in the complexity of amyotrophic lateral sclerosis (ALS). BMC Med. 2021;19(1):13). We hypothesize that population level differences in the gut microbiome will predict the incidence of Alzheimer's disease using machine learning methods. Cross-sectional analyses were performed in R, using two large, open-access microbiome datasets (n = 959 and n = 2012). Countries in these datasets were grouped based on Alzheimer's disease incidence and the gut microbiome profiles compared. In countries with a high incidence of Alzheimer's disease, there is a significantly lower diversity of the gut microbiome (P < 0.05). A permutational analysis of variance test (P < 0.05) revealed significant differences in the microbiome profile between countries with high versus low incidence of Alzheimer's disease with several contributing taxa identified: at a species level Escherichia coli, and at a genus level Haemophilus and Akkermansia were found to be reproducibly protective in both datasets. Additionally, using machine learning, we were able to predict the incidence of Alzheimer's disease within a country based on the microbiome profile (mean area under the curve 0.889 and 0.927). We conclude that differences in the microbiome can predict the varying incidence of Alzheimer's disease between countries. Our results support a key role of the gut microbiome in neurodegeneration at a population level.

Baseline abundance of Akkermansia muciniphila and Bacteroides acidifaciens in a healthy state predicts inflammation associated tumorigenesis in the AOM/DSS mouse model

Numerous studies demonstrate that intestinal microbiota contribute to colorectal cancer (CRC), which is often associated with dysbiosis. Most of the data were obtained from studies on CRC patients, making it challenging to determine whether alterations in microbiota are a consequence of the pathology or whether they actively drive its progression. Several studies using laboratory animals suggest that gut microbiota may be involved in both the onset and progression of CRC. In the present study we utilized the azoxymethane-dextran sulfate sodium (AOM/DSS) mouse model of CRC to investigate the contribution of healthy-state microbiota to inflammation-associated tumorigenesis. Two cohorts of C57BL/6 mice harboring different intestinal microbiota demonstrated different susceptibility to AOM/DSS treatment. Sequencing of 16S rRNA bacterial DNA from fecal samples revealed Akkermansia muciniphila and Bacteroides acidifaciens as marker features in the healthy-state microbiota (before AOM/DSS administration), which showed a strong positive correlation with tumor incidence. Moreover, the healthy-state abundance of these markers, considered beneficial bacteria, was strongly positively correlated with the sulfate-reducing bacteria Desulfovibrio fairfieldensis identified as a marker of chronic colitis-associated microbiota. Furthermore, the abundances of these marker features, associated with CRC outcome, correlated with the expression of interferon gamma and nitric oxide synthase 2 genes in colon tissue during the early stage of DSS-induced intestinal inflammation. In contrast to multiple studies demonstrating the anti-inflammatory properties of A. muciniphila and B. acidifaciens, our results point out their potential adverse effect under specific conditions of genotoxicity and inflammation in the intestine. Taken together, our findings suggest a complex, context-dependent role of commensal microbiota in inflammation-associated dysbiosis and CRC.

Complex carbohydrates catabolism capacity of bladder microbiota inhabiting healthy and overactive female bladders

Overactive bladder syndrome (OAB) is a poorly understood symptom complex that affects 40% of females over the age of 40, with clinical features including urinary urgency and incontinence. In addition to inflammation, oxidative stress, nerve damage and reduced blood flow, alterations in the urinary microbiome (urobiome), specifically in bladder bacterial diversity, have been reported to be associated with OAB. Bladder bacteria are members of the urobiome along with viruses, archaea, fungi, and protozoans. The urobiome metabolism, particularly in relationship to host complex sugars (glycans), has been investigated recently in terms of glycosaminoglycan (GAG) utilization. Nevertheless, other urinary free oligosaccharides (FOS) have not yet been explored in both OAB and urobiome contexts. Similarly, a comprehensive search of microbial genes involved in host glycan metabolism in the bladder of adult females with or without OAB has not yet been reported. In this study, we investigated urinary FOS by mass spectrometry in women without OAB (asymptomatic controls), with OAB without incontinence (dry OAB), or with OAB with incontinence (wet OAB or urgency urinary incontinence, UUI). We also questioned the ability of commensal bladder bacteria to digest these FOS and other glycans, using bioinformatic tools to query publicly available bladder genomes isolated from affected and unaffected adult females to identify genes that encode polysaccharide lyases (PL) and glycoside hydrolases (GH). Our results show that FOS are present in a similar level in affected and unaffected controls with a few exceptions: ten FOS were found to differ between the OAB dry groups and either the control (four) or UUI (six) groups. Our results indicate that bladder microbiota from adult females both with and without OAB have the genetic capacity to digest host glycans and dietary sugars with subtle differences. Bladder bacteria isolated from females with OAB possess more GH/PL genes for host mucins, whereas bladder bacteria from controls possess more GH/PL genes for GAG digestion. In the control group, specifically, the genus Streptococcus possessed genes for the PL8 and GH88 enzymes, known to be involved in host GAG digestion. These novel bioinformatic data can enable future biochemical exploration of the urobiome's metabolism toward specific host glycans, such as GAGs, mucins O-glycans and N-glycans.

Acidipropionibacterium acidipropionici, a propionate-producing bacterium, contributes to GPR41 signaling and metabolic regulation in high-fat diet-induced obesity in mice

Obesity is a major healthcare problem worldwide and is induced by excess energy intake, resulting in gut microbial composition and microbial diversity changes. Through fermentation of dietary fibers, short-chain fatty acids (SCFAs) act as host energy sources and signaling molecules via G protein-coupled receptors such as GPR41. Acidipropionibacterium acidipropionici is widely used in many applications; however, in vivo studies on the beneficial effect of A. acidipropionici via propionate production and host energy homeostasis are unclear. Therefore, this study aimed to investigate the beneficial metabolic effects of A. acidipropionici by focusing on GPR41 signaling in a high-fat diet (HFD)-induced obesity mouse model. Here, we demonstrated that A. acidipropionici OB7439 improved host metabolism in HFD-induced obesity in mice. The intake of A. acidipropionici OB7439 improved metabolism in HFD-induced obese mice by increasing propionate production, regulating glucose tolerance, and inhibiting hepatic inflammation via GPR41 signaling. Our findings shed light on the potential of using A. acidipropionici OB7439 as an SCFA producer for the prevention and treatment of metabolic disorders. Based on these results, we suggest that A. acidipropionici may be a potential therapeutic bacterium that inhibits obesity and modulates the gut microbial community.

Unravelling the Glycan Code: Molecular Dynamics and Quantum Chemistry Reveal How O-Glycan Functional Groups Govern OgpA Selectivity in Mucin Degradation by Akkermansia muciniphila

Mucins, heavily O-glycosylated glycoproteins, are a key component of mucus, and certain gut microbiota, including Akkermansia muciniphila, can utilise mucin glycans as a carbon source. Akkermansia muciniphila produces the O-glycopeptidase enzyme OgpA, which cleaves peptide bonds at the N-terminus of serine (Ser) or threonine (Thr) residues carrying O-glycan substitutions, with selectivity influenced by the O-glycan functional groups. Using molecular dynamics (MD) simulations and quantum chemistry calculations, we explored how different O-glycan groups affect OgpA's selectivity. Our results show that peptides bind to the enzyme via hydrogen bonds, π-π interactions, van der Waals forces and electrostatic interactions, with key residues, including Tyr90, Val138, Gly176, Tyr210 and Glu91, playing important roles. The primary determinant of selectivity is the interaction between the peptide's functional group and the enzyme's binding cavity, while peptide-enzyme interface interactions are secondary. Quantum chemistry calculations reveal that OgpA prefers peptides with a lower electrophilic character. This study provides new insights into mucin degradation by gut microbiota enzymes, advancing our understanding of this critical biological process.

Akkermansia muciniphila inhibits jejunal lipid absorption and regulates jejunal core bacteria

Insufficiency of Akkermansia muciniphila (Akk) has been implicated in the pathogenesis of metabolic diseases, and administration or restoration of Akk has ameliorated these disorders. Recently, Pasteurized Akk (PA-Akk) has been approved as a functional food. However, the impact of Akk on lipid absorption in the proximal intestine, which is directly exposed to orally administered Akk, remains largely unexplored. In this study, we orally administered Akk and PA-Akk to mice and investigated the subsequent lipid absorption. Long-term administration of Akk resulted in reduced lipid deposits in the liver and adipocytes, along with improved glucose metabolism. This was primarily attributed to a reduction in lipid absorption by epithelial cells in the proximal jejunum. Mechanistically, Akk activated AMP-activated protein kinase (AMPK) and directly inhibit lipids absorption in both mouse and human jejunal epithelial cells. Furthermore, we demonstrated that Akk treatment, but not PA-Akk treatment, promotes the abundance of genera that are highly abundant in the normal jejunum and belong to the phylum Firmicutes. Thus, our study concludes that oral administration of Akk provides beneficial effects on metabolism, partially through inhibiting jejunal lipid absorption and promoting the abundance of core jejunal microbes.

Immune tolerance to foreign antigens in the intestine: mechanisms mediated by CD4＋ T cells

The immune system encounters a diverse array of antigens, both self and foreign, necessitating mechanisms to maintain tolerance and prevent harmful inflammatory responses. CD4＋ T cells, crucial in orchestrating immune responses, play a critical role in mediating tolerance to both self and foreign antigens. While the mechanisms of CD4＋ T cell-mediated tolerance to self-antigens are well-documented, the understanding of tolerance to foreign antigens, including those from commensal microbes and food, remains incomplete. This review discusses recent progress in the mechanisms underlying immune tolerance to foreign antigens, with a focus on the role of CD4＋ T cells. We explore how inflammatory and tolerogenic CD4＋ T cell subsets are developed and maintained. Moreover, we delve into the complexities of immune responses to commensal microbes and food antigens by reviewing recent findings, highlighting the immunological contexts that shape immune tolerance. Understanding these mechanisms enhances our comprehension of how immune tolerance is established and sustained, providing insights into potential therapeutic approaches for managing chronic inflammatory diseases resulting from a loss of immune tolerance to foreign antigens. [BMB Reports 2025; 58(4): 158-168].

Protective Effect of Dietary Fiber on Blood Pressure and Vascular Dysfunction Through Regulation of Sympathetic Tone and Immune Response in Genetic Hypertension

The mechanisms underlying the antihypertensive effect of dietary fibers remain poorly understood. This study investigates whether dietary fiber supplementation can prevent cardiovascular damage and high blood pressure in a genetic model of neurogenic hypertension. Six-week-old male spontaneously hypertensive rats (SHR) and their respective normotensive control, Wistar Kyoto rats (WKY), were divided into four groups: Untreated WKY, untreated SHR, SHR treated with resistant starch (SHR + RS), and SHR treated with inulin-type fructans (SHR + ITF) for 12 weeks. Additionally, a faecal microbiota transplantation (FMT) experiment was conducted, transferring faecal content from treated SHR donors to recipient SHRs. A diet rich in RS fiber reduced vascular oxidative stress, inflammation, and high blood pressure. These protective effects were associated with a reshaped gut microbiota, leading to increased short-chain fatty acid production, reduced endotoxemia, decreased sympathetic activity, and a restored balance between Th17 and Treg lymphocytes in mesenteric lymph nodes and aorta. Elevated plasma levels of acetate and butyrate in the SHR + RS group correlated with increased expression of aortic GPR41, GRP43 and PPARδ. Conversely, ITF treatment failed to prevent hypertension or endothelial dysfunction in SHR. FMT from the SHR + RS group to recipient SHR partially replicated these beneficial effects. This study highlights the antihypertensive benefits of dietary insoluble RS fiber, which are attributed to enhanced short-chain fatty acids production in the gut. This leads to improved gut permeability, reduced sympathetic tone, and diminished vascular T-cell accumulation. Therefore, dietary interventions with RS fiber may offer promising therapeutic strategies for preventing hypertension.

Epigenetic phase variation in the gut microbiome enhances bacterial adaptation

The human gut microbiome within the gastrointestinal tract continuously adapts to variations in diet, medications, and host physiology. A strategy for bacterial genetic adaptation is epigenetic phase variation (ePV) mediated by bacterial DNA methylation, which can regulate gene expression, enhance clonal heterogeneity, and enable a single bacterial strain to exhibit variable phenotypic states. Genome-wide and site-specific ePVs have been characterized in human pathogens' antigenic variation and virulence factor production. However, the role of ePV in facilitating adaptation within the human microbiome remains poorly understood. Here, we comprehensively cataloged genome-wide and site-specific ePV in human infant and adult gut microbiomes. First, using long-read metagenomic sequencing, we detected genome-wide ePV mediated by complex structural variations of DNA methyltransferases, highlighting those associated with antibiotics or fecal microbiota transplantation. Second, we analyzed a collection of public short-read metagenomic sequencing datasets, uncovering a great prevalence of genome-wide ePV in the human gut microbiome. Third, we quantitatively detected site-specific ePVs using single-molecule methylation analysis to identify dynamic variation associated with antibiotic treatment or probiotic engraftment. Finally, we performed an in-depth assessment of an Akkermansia muciniphila isolate from an infant, highlighting that ePVs can regulate gene expression and enhance the bacterial adaptive capacity by employing a bet-hedging strategy to increase tolerance to differing antibiotics. Our findings indicate that epigenetic modifications are a common strategy used by gut bacteria to adapt to the fluctuating environment.

Soy-based purified ingredient diet affects mouse gut permeability and the microbiome in fragile X mice

Introduction

Gastrointestinal problems including vomiting, reflux, flatulence, diarrhea, constipation and colic are common comorbidities in fragile X syndrome. There is accumulating evidence suggesting that leaky gut syndrome causes neurological phenotypes. Although fragile X messenger ribonucleoprotein is ubiquitously expressed, there is a dearth of knowledge regarding its role outside of the brain including effects on gut dysfunction in fragile X. The aim of this study was to generate novel data on gastrointestinal barrier function and the gut microbiome in response to Fmr1 genotype, sex and diet in mice.

Methods

Fmr1KO male mice and littermate controls in an FVB background were maintained on two purified ingredient diets (AIN-93G with casein protein versus soy protein isolate) versus two standard chows (Teklad 2019 with wheat, corn and yeast protein versus Purina 5015 with wheat, soy, corn, yeast and whey protein sources). Gut permeability was quantified by FITC-dextran levels in blood plasma. The cecal microbiome was identified by 16S rRNA sequencing. In addition, gut permeability was tested in Fmr1KO mice in the C57BL/6 J background maintained on casein- and soy protein isolate-based AIN-93G versus Teklad 2019.

Results

Knockout of the Fmr1 gene in FVB mice did not affect gut permeability. Soy protein isolate-based AIN-93G increased gut permeability. Beta-diversity of the cecal microbiome was significantly altered as a function of the four test diets. Akkermansia_muciniphila was increased in Fmr1KO mice fed AIN-93G while unnamed species within the genus Anaerovorax and family Ruminococcaceae were increased and the order Clostridales decreased in Fmr1KO mice fed AIN-93G/soy. Fmr1KO mice in the C57BL/6 J background exhibited increased gut permeability in response to soy protein.

Discussion

These findings regarding the effects of diet on gut permeability and the microbiome have important implications for experimental design. Single-source diets are ubiquitously used to maintain laboratory animals for medical research and feed details are frequently not reported in publications. Diet/phenotype interactions could have a large impact on inter-laboratory replicability in premedical research. For infants with fragile X, early-life diet could impact the severity of disease outcomes.

Impact of a High-Fat Diet on the Gut Microbiome: A Comprehensive Study of Microbial and Metabolite Shifts During Obesity

Over the last few decades, the prevalence of metabolic diseases such as obesity, diabetes, non-alcoholic fatty liver disease, hypertension, and hyperuricemia has surged, primarily due to high-fat diet (HFD). The pathologies of these metabolic diseases show disease-specific alterations in the composition and function of their gut microbiome. How HFD alters the microbiome and its metabolite to mediate adipose tissue (AT) inflammation and obesity is not well known. Thus, this study aimed to identify the changes in the gut microbiome and metabolomic signatures induced by an HFD to alter obesity. To explore the changes in the gut microbiota and metabolites, 16S rRNA gene amplicon sequencing and metabolomic analyses were performed after HFD and normal diet (ND) feeding. We noticed that, at taxonomic levels, the number of operational taxonomic units (OTUs), along with the Chao and Shannon indexes, significantly shifted in HFD-fed mice compared to those fed a ND. Similarly, at the phylum level, an increase in Firmicutes and a decrease in Bacteroidetes were noticed in HFD-fed mice. At the genus level, an increase in Lactobacillus and Ruminococcus was observed, while Allobaculum, Clostridium, and Akkermansia were markedly reduced in the HFD group. Many bacteria from the Ruminococcus genus impair bile acid metabolism and restrict weight loss. Firmicutes are efficient in breaking down complex carbohydrates into short-chain fatty acids (SCFAs) and other metabolites, whereas Bacteroidetes are involved in a more balanced or efficient energy extraction. Thus, an increase in Firmicutes over Bacteroidetes enhances the absorption of more calories from food, which may contribute to obesity. Taken together, the altered gut microbiota and metabolites trigger AT inflammation, which contributes to metabolic dysregulation and disease progression. Thus, this study highlights the potential of the gut microbiome in the development of therapeutic strategies for obesity and related metabolic disorders.

Heat-killed Lacticaseibacillus paracasei 6235 is more effective than live on DSS-induced colitis via modulation of intestinal microbiota and MAPK/NF-κB signaling pathways

This study compared the protective effects of both live Lacticaseibacillus paracasei 6235 (LLP 6235) and heat-killed Lacticaseibacillus paracasei 6235 (HK-LP 6235) on ulcerative colitis. Using a dextran sulfate sodium (DSS)-induced colitis mouse model, we evaluated physiological state, colon tissue integrity, inflammatory factors, tight junction (TJ) proteins, and intestinal microbiota variations. The findings demonstrated that both LLP 6235 and HK-LP 6235 have the capacity to mitigate colitis damage, enhance TJ protein levels, and restore colon morphology. In addition, these interventions modulated the intestinal inflammatory response by inhibiting pro-inflammatory factors and upregulating anti-inflammatory factors through the mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways. Moreover, treatment with LLP 6235 and HK-LP 6235 significantly altered intestinal microbiota diversity, increased the relative abundance of beneficial bacteria, and regulated the short-chain fatty acid (SCFA) levels. Spearman correlation analysis revealed a strong association between TJ proteins, SCFAs, intestinal microbiota, and inflammatory response, suggesting that LLP 6235 and HK-LP 6235 may provide an effective approach to colitis prevention. In conclusion, LLP 6235 and HK-LP 6235 have similar abilities; furthermore, HK-LP 6235 modulated the intestinal microbiota through lipid metabolic pathways, resulting in a greater improvement. Moreover, considering the high stability and safety of prebiotics and their wide applicability, HK-LP 6235 is recommended for use as a modulator of intestinal inflammatory diseases.

Akkermansia muciniphila helps in the recovery of lipopolysaccharide-fed mice with mild intestinal dysfunction

Background

Mild intestinal dysfunction, linked to subtle yet significant health issues, can be induced by lipopolysaccharide (LPS), a Gram-negative bacterial component that disrupts gut function and triggers inflammation. Akkermansia muciniphila has shown promise as a probiotic for gut health due to its roles in mucin degradation and short-chain fatty acid production. This study explores the therapeutic effects of Akkermansia muciniphila on LPS-induced mild intestinal dysfunction in mice.

Methods

Thirty-eight 6-week-old C57BL/6 mice were split into control (n = 19) and LPS-treated (n = 19) groups. LPS-treated mice received 300 μg/kg/day of LPS for 4 weeks, followed by Akkermansia muciniphila supplementation at 41 mg/kg/day (Akk1) or 82 mg/kg/day (Akk2) for another 4 weeks. Gut microbiota was analyzed via metagenomic sequencing, and gene expression was evaluated through transcriptomics.

Results

LPS significantly altered gut microbiota, reducing diversity and increasing pathogenic genera like Lachnoclostridium. Akkermansia muciniphila supplementation, particularly at higher doses, partially restored gut microbiota by increasing beneficial genera such as Muribaculum. Transcriptomics showed that LPS induced immune and inflammatory responses, while Akkermansia muciniphila reduced these effects by modulating pathways like TNF and NF-kappa B signaling.

Conclusion

Akkermansia muciniphila mitigates LPS-induced gut dysfunction by restoring microbiota balance and modulating immune responses, highlighting its potential as a therapeutic agent for gut health.

Specific microbial ratio in the gut microbiome is associated with multiple sclerosis

Gut microbiota dysbiosis is associated with multiple sclerosis (MS), but the causal relationship between specific gut bacteria and MS pathogenesis remains poorly understood. Therefore, we profiled the stool microbiome of people with MS (PwMS) and healthy controls (HC) using shotgun metagenomic sequencing. PwMS showed a distinct microbiome compared to HC, with Prevotella copri (PC) and Blautia species as drivers of microbial communities in HC and PwMS, respectively. Administration of MS-driving Blautia species (Blautia wexlerae; BW) to mice resulted in increased levels of gut inflammatory markers and altered microbiota with increased capacity to induce proinflammatory cytokines. Utilizing experimental autoimmune encephalomyelitis (EAE), an animal model of MS, we identified a lower gut Bifidobacterium to Akkermansia ratio as a hallmark of the disease. BW-administered mice also showed a lower Bifidobacterium to Akkermansia ratio pre-EAE induction which correlated with increased disease severity post-EAE induction. The importance of the Bifidobacterium to Akkermansia ratio at the species level, lower Bifidobacterium adolescentis to Akkermansia muciniphila (BA:AM), was validated in our MS cohort and a large International Multiple Sclerosis Microbiome Study. Thus, our findings highlight the BA:AM ratio as a potential gut microbial marker in PwMS, opening avenues for microbiome-based diagnosis, prognosis, and therapy in MS.

The worldview of Akkermansia muciniphila, a bibliometric analysis

Akkermansia muciniphila (A. muciniphila), a critical bacterium within the gut microbiota, plays a key role in human health and immunomodulation. Since its identification in 2004, A. muciniphila has emerged as a significant agent in treating metabolic diseases, gastroenterological diseases, and tumor immunotherapy. Its rapid ascent in scientific translation underscores its importance in gut microbiome research. However, there has been a lack of visualization and analysis of the rapidly occurring commercialization in this field, which has critically hindered insights into the current knowledge structure and understanding of the cutting-edge of the discipline. This study employs the Web of Science Core Collection (WOSCC) and Innography platforms to provide the first comprehensive analysis of A. muciniphila's academic progresses and commercialization over the past two decades, highlighting its growing prominence in global health research. Our analysis delineates that, following the academic trajectory, the evolution of A. muciniphila patents from foundational research through to application development and maturity, with particular emphasis on its expansive potential in emerging fields, including gastroenterological disorders, non-alcoholic fatty liver disease, cancer immunotherapy, stress management, and neurodegenerative disease treatment. Concluding, A. muciniphila presents as a next-generation probiotic with vast implications for human health. Our findings provide essential insights for future research and product development, contributing to the advancement of this burgeoning field.

Akkermansia muciniphila: promises and pitfallsfor next-generation beneficial microorganisms

Akkermansia muciniphila, a microorganism ubiquitously colonizing the mucosal layer of the human gut, has garnered significant scientific interest as a promising candidate for probiotic therapeutics. Its persistent identification in both laboratory and living organism studies underscores its potential physiological benefits, positioning it as a bacterium of paramount importance in promoting host health. This review examines the diversity and abundance of gut microbiota members, emphasizing the identification of microbial species engaged in cross-feeding networks with A. muciniphila. Insightful exploration into the mechanisms of cross-feeding, including mucin-derived nutrient exchange and metabolite production, unveils the intricate dynamics shaping microbial community stability. Such interactions contribute not only to the availability of essential nutrients within the gut environment but also to the production of metabolites influencing microbial community dynamics and host health. In conclusion, the cumulative evidence from in vitro and in vivo perspectives substantiates the notion that A. muciniphila holds tremendous promise as a next-generation probiotic. By leveraging its unique physiological benefits, particularly in mucosal health and metabolic regulation, A. muciniphila stands poised to revolutionize the landscape of probiotic interventions for enhanced host well-being.

Advances in intestinal epithelium and gut microbiota interaction

The intestinal epithelium represents a critical interface between the host and external environment, serving as the second largest surface area in the human body after the lungs. This dynamic barrier is sustained by specialized epithelial cell types and their complex interactions with the gut microbiota. This review comprehensively examines the recent advances in understanding the bidirectional communication between intestinal epithelial cells and the microbiome. We briefly highlight the role of various intestinal epithelial cell types, such as Paneth cells, goblet cells, and enteroendocrine cells, in maintaining intestinal homeostasis and barrier function. Gut microbiota-derived metabolites, particularly short-chain fatty acids and bile acids, influence epithelial cell function and intestinal barrier integrity. Additionally, we highlight emerging evidence of the sophisticated cooperation between different epithelial cell types, with special emphasis on the interaction between tuft cells and Paneth cells in maintaining microbial balance. Understanding these complex interactions has important implications for developing targeted therapeutic strategies for various gastrointestinal disorders, including inflammatory bowel disease, metabolic disorders, and colorectal cancer.

ILC3s regulate the gut microbiota via host intestinal galactosylation to limit pathogen infection in mice

Host immunity and commensal bacteria synergistically maintain intestinal homeostasis and mediate colonization resistance against pathogens. However, the molecular and cellular mechanisms remain unclear. Here, with a mouse infection model of Citrobacter rodentium, a natural mouse intestinal pathogen that mimics human enteropathogenic Escherichia coli and enterohaemorrhagic Escherichia coli, we find that group 3 innate lymphoid cells (ILC3s) can protect the host from infection by regulating gut microbiota. Mechanistically, ILC3s can control gut dysbiosis through IL-22-dependent regulation of intestinal galactosylation in mice. ILC3 deficiency led to an increase in intestinal galactosylation and the expansion of commensal Akkermansia muciniphila in colonic mucus. The increased A. muciniphila and A. muciniphila-derived metabolic product succinate further promoted the expression of pathogen virulence factors tir and ler, resulting in increased susceptibility to C. rodentium infection. Together, our data reveal a mechanism for ILC3s in protecting against pathogen infection through the regulation of intestinal glycosylation and gut microbiota metabolism.

Quercetin-Driven Akkermansia Muciniphila Alleviates Obesity by Modulating Bile Acid Metabolism via an ILA/m6A/CYP8B1 Signaling

Global health is increasingly challenged by the growing prevalence of obesity and its associated complications. Quercetin, one of the most important dietary flavonoids, is being explored as an effective therapy for obesity with its mechanism remains understudied. Here in this study, it is demonstrated that quercetin intervention significantly reverses obesity-related phenotypes through reshaping the overall structure of microbiota, especially boosting colonization of the beneficial gut commensal Akkermansia muciniphila (A. muciniphila). Enrichment of A. muciniphila leads to generate more indole-3-lactic acid (ILA) to upregulate the expression of 12α-hydroxylase (CYP8B1) via fat mass and obesity-associated protein (FTO)/ N6-methyladenosine (m6A)/YTHDF2 manner, thereby facilitating cholesterol converts to cholic acid (CA). CA in turn drastically suppresses lipid accumulation via activating the farnesoid X receptor (FXR) in adipose tissue. This work introduces a novel therapeutic target for addressing obesity and expands upon the current limited understanding of the mediator function of m6A modifications in microorganism-influenced bile acid (BA) metabolism.

Effects of methylglyoxal on intestine and microbiome composition in aged mice

BACKGROUND

Methylglyoxal (MGO), a highly reactive precursor of advanced glycation end products (AGEs), is endogenously produced and prevalent in various ultra-processed foods. MGO has emerged as a significant precursor implicated in the pathogenesis of type 2 diabetes and neurodegenerative diseases. To date, the effects of dietary MGO on the intestine have been limited explored. Thus, this study investigates the impact of prolonged oral administration of MGOs on gut health in aged mice.

METHODS

Aged mice received MGO chronically (100 mg/kg/day) for 4 weeks Intestinal samples were analyzed using RT-PCR and immunohistochemistry for proinflammatory cytokines, permeability markers, and tight junction proteins. 16S rRNA gene-based microbiome analysis was also performed to characterize microbiome composition and its metabolic potential.

RESULTS

MGO treatment induced notable alterations at the intestinal level, characterized by an increased formation of MGO-glycated proteins with a concurrent induction of a pro-inflammatory status and reduced expression and delocalization of zonulin-1 and occludin, tight junction proteins. Changes in intestinal morphology were also observed, including hyperproliferation of Paneth cells and an augmented thickness of the intestinal mucus layer, as indicated by immunohistochemical data from MGO-treated mice. Investigation into the microbiota composition revealed that MGO is effective in selectively modifying its composition and metabolic pathways. A decreased abundance of bacterial genera associated with the production of acetic and butyric acids (i.e. Harryflintia, Intestinimonas and Ruminococcaceae genera) and a substantial increase in Lachnospiraceae and Akkermansia genera were found in MGO-treated mice.

CONCLUSION

These findings highlight how dietary MGO can affect intestinal balance, providing valuable insights into the potential links between glycotoxins, gut microbiota, and overall gut functionality.

Akkermansia muciniphila: biology, microbial ecology, host interactions and therapeutic potential

Akkermansia muciniphila is a gut bacterium that colonizes the gut mucosa, has a role in maintaining gut health and shows promise for potential therapeutic applications. The discovery of A. muciniphila as an important member of our gut microbiome, occupying an extraordinary niche in the human gut, has led to new hypotheses on gut health, beneficial microorganisms and host-microbiota interactions. This microorganism has established a unique position in human microbiome research, similar to its role in the gut ecosystem. Its unique traits in using mucin sugars and mechanisms of action that can modify host health have made A. muciniphila a subject of enormous attention from multiple research fields. A. muciniphila is becoming a model organism studied for its ability to modulate human health and gut microbiome structure, leading to commercial products, a genetic model and possible probiotic formulations. This Review provides an overview of A. muciniphila and Akkermansia genus phylogeny, ecophysiology and diversity. Furthermore, the Review discusses perspectives on ecology, strategies for harnessing beneficial effects of A. muciniphila for human mucosal metabolic and gut health, and its potential as a biomarker for diagnostics and prognostics.

Efficacy Evaluation of Selenium-enriched Akkermansia muciniphila in the Treatment of Colon Tumor Mice

Selenium (Se)-enriched probiotics possess a variety of beneficial properties and are widely used in specialty foods and biomedical applications. Akkermansia muciniphila (AM) is being considered a promising candidate for the "next generation probiotics (NGPs)," which play an essential role in the field of tumor therapy. However, there are no studies on the efficacy of Se-enriched A. muciniphila (Se-AM) in the field of tumor therapy. The present study utilized inorganic Se bio-enrichment for the preparation of Se-AM. To evaluate the killing effect of Se-AM on CT26 cells, the actual efficacy and safety of Se-AM were investigated in a mouse model of colon cancer. The results showed that the Se-AM-cell lysate was able to significantly kill CT26 cells, but this killing effect was progressively weakened with decreasing concentrations of Se-AM-cell lysate. The results of animal experiments showed that Se-AM was able to safely and effectively curb the disease course of mice with colon tumors, reduce the tumor volume, lower the levels of IL-1β and IL-6, and increase the levels of TNF-α in the colon of mice. Furthermore, treatment with Se-AM in mice led to a restoration of gut microbiota diversity, reaching levels similar to those observed in healthy controls. This restoration was accompanied by a significant enrichment of beneficial genera, such as Turicibacter, Butyricimonas, Prevotella, and Akkermansia. In summary, Se-AM prepared in this study was able to produce effective killing of CT26 cells directly and played a substantial therapeutic role in a mouse model of colon tumors constructed from CT26 cells. Se-AM had no adverse effect on the heart, liver, spleen, lungs, and kidney of mice and demonstrated a high level of safety. Meanwhile, Se-AM significantly raised the level of the Shannon index and the ratio of Firmicutes to Bacteroidetes of the gut microbiota in mice, indicating its ability to regulate the homeostasis of the microbiota. These results imply that Se-AM has great application value in the field of colon cancer treatment.

Big lessons from the little Akkermansia muciniphila in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most frequently occurring type of liver tumor and is considered one of the most common primary malignant neoplasms. The prognosis for HCC is dismal because of its complicated etiology and high level of medication resistance. Immunotherapy is presently regarded as one of the most effective therapeutic options for HCC; nevertheless, because of the disturbance of intestinal flora, immunotherapy shows low antitumor efficacy. An increasing body of research indicates that intestinal flora, particularly Akkermansia muciniphila (A. muciniphila), is vital for the treatment of tumors. Studies have demonstrated that the diminished effectiveness of immunotherapy in cancer patients is associated with a reduction in A. muciniphila levels, suggesting that increasing A. muciniphila levels significantly enhance the efficacy of immunotherapy. A. muciniphila functions as a gut probiotic and can treat and prevent a wide range of illnesses, including cancer. Consequently, preserving A. muciniphila abundance is enough to prevent and lower the danger of developing cancer disorders. In this review, we critically evaluate the current body of research on A. muciniphila, with a primary focus on its biological properties and functions. The different illnesses that A. muciniphila treats were then discussed, particularly the way it works with liver cancer. This review aims to give a novel treatment plan for patients with HCC as well as a theoretical foundation for improving HCC immunotherapy.