Novel tripeptide RKH derived from Akkermansia muciniphila protects against lethal sepsis

Live and pasteurized Akkermansia muciniphila ameliorates diabetic cognitive impairment by modulating gut microbiota and metabolites in db/db mice

The established role of disturbances in the microbiota-gut-brain axis in the development of diabetic cognitive impairment (DCI) has long been recognized. It has shown the potential of Akkermansia muciniphila (A. muciniphila) in improving metabolic disorders and exerting anti-inflammatory effects. However, there remains a lack of comprehensive understanding regarding the specific effects and mechanisms underlying the treatment of DCI with A. muciniphila. This study aimed to evaluate the potential of A. muciniphila in alleviating DCI in db/db mice. Eleven-week-old db/db mice were administered either live or pasteurized A. muciniphila (5 × 109 CFU/200 μL) for a duration of eight weeks. Administering live A. muciniphila significantly ameliorated cognitive impairments, improved the synaptic ultrastructure, and inhibited hippocampal neuron loss in the CA1 and CA3 subregions in db/db mice. Both live and pasteurized A. muciniphila effectively mitigated neuroinflammation. Moreover, live A. muciniphila increased the relative abundance of Lactococcus and Staphylococcus, whereas pasteurized A. muciniphila increased the relative abundance of Lactobacillus, Prevotellaceae_UCG_001, and Alistipes. Supplementation of A. muciniphila also induced alterations in serum and brain metabolites, with a particular enrichment observed in tryptophan metabolism, glyoxylate and dicarboxylate metabolism, nitrogen metabolism, and pentose and glucuronate interconversions. Correlation analysis further demonstrated a direct and substantial correlation between the altered gut microbiota and the metabolites in the serum and brain tissue. In conclusion, the results indicate that live A. muciniphila demonstrated greater efficacy compared to pasteurized A. muciniphila. The observed protective effects of A. muciniphila against DCI are likely mediated through the neuroinflammation and microbiota-metabolites-brain axis.

Akkermansia muciniphila-derived pentadecanoic acid enhances oxaliplatin sensitivity in gastric cancer by modulating glycolysis

Accumulating evidence has proved the close association between alterations in gut microbiota and resistance to chemotherapeutic drugs. However, the potential roles of gut microbiota in regulating oxaliplatin sensitivity in gastric cancer (GC) have not been investigated before. We first found that antibiotic treatment diminished the therapeutic efficacy of oxaliplatin in a GC mouse model. Importantly, this effect could be transmitted to germ-free mice via fecal microbiota transplantation, indicating a potential role of gut microbiota modulation in oxaliplatin efficacy. Further, metagenomics data showed that Akkermansia muciniphila (A. muciniphila) ranked first among the bacterial species with decreased relative abundances after antibiotic treatment. Metabolically active A. muciniphila promotes oxaliplatin efficacy. As shown by metabolomics analysis, the metabolic pattern of gut microbiota was disrupted with significantly downregulated levels of pentadecanoic acid (PEA), and the use of PEA significantly promoted oxaliplatin efficacy. Mechanistically, FUBP1 positively regulated aerobic glycolysis of GC cells to hinder the therapeutic efficacy of oxaliplatin. A. muciniphila-derived PEA functioned as an inhibitory factor of glycolysis by directly antagonizing the activity of FUBP1, which potentiated GC responses to oxaliplatin. Our research suggested a key role for intestinal A. muciniphila and its metabolite PEA in promoting oxaliplatin efficacy, thus providing a new perspective for probiotic and prebiotic intervention in GC patients during chemotherapy.

Bacillus halotolerans attenuates inflammation induced by enterotoxigenic Escherichia coli infection in vivo and in vitro based on its metabolite soyasaponin I regulating the p105-Tpl2-ERK pathway

Soyasaponins, recognized for their anti-inflammatory and antioxidant effects, have not yet been fully explored for their role in combating enterotoxigenic Escherichia coli (ETEC) infections. Recent findings identified them in small-molecule metabolites of Bacillus, suggesting their broader biological relevance. This research screened 88 strains of B. halotolerans, identifying the strain BH M20221856 as significantly inhibitory against ETEC growth in vitro. It also reduced cellular damage and inflammatory response in IPEC-J2 cells. The antimicrobial activity of BH M20221856 was attributed to its small-molecule metabolites rather than secretory proteins. A total of 69 small molecules were identified from the metabolites of BH M20221856 using liquid chromatography mass spectrometry/mass spectrometry (LC-MS/MS). Among these, soyasaponin I (SoSa I) represented the largest multiple change in the enrichment analysis of differential metabolites and exhibited potent anti-ETEC effects in vivo. It significantly reduced the bacterial load of E. coli in mouse intestines, decreased serum endotoxin, D-lactic acid, and oxidative stress levels and alleviated intestinal pathological damage and inflammation. SoSa I enhanced immune regulation by mediating the p105-Tpl2-ERK signaling pathway. Further evaluations using transepithelial electrical resistance (TEER) and cell permeability assays showed that SoSa I alleviated ETEC-induced damage to epithelial barrier function. These results suggest that BH M20221856 and SoSa I may serve as preventative biologics against ETEC infections, providing new insights for developing strategies to prevent and control this disease.

[Association between the structure of intestinal flora and inflammatory response in children with sepsis: a prospective cohort study]

OBJECTIVES

To investigate the structural characteristics of intestinal flora in children with sepsis and its association with inflammatory response.

METHODS

A prospective cohort study was conducted. The children with sepsis who were admitted from December 2021 to January 2023 were enrolled as the sepsis group, and the children with non-sepsis who were admitted during the same period were enrolled as the non-sepsis group. The two groups were compared in terms of the distribution characteristics of intestinal flora, peripheral white blood cell count (WBC), C reactive protein (CRP), and cytokines, and the correlation of the relative abundance of fecal flora with WBC, CRP, and cytokines was analyzed.

RESULTS

At the genus level, compared with the non-sepsis group, the sepsis group had significantly lower relative abundance of Akkermansia, Ruminococcus, and Alistipes and significantly higher relative abundance of Enterococcus, Streptococcus, and Staphylococcus (P<0.05). At the phylum level, Proteobacteria was the dominant phylum (37.46%) in the group of children with a score of ≤70 from the Pediatric Critical Illness Score (PICS), and Firmicutes was the dominant phylum in the group of children with a score of 71-80 or 81-90 from the PICS (72.20% and 43.88%, respectively). At the genus level, among the 18 specimens, 5 had a relative abundance of >50% for a single flora. Compared with the non-sepsis group, the sepsis group had significant higher levels of WBC, CRP, interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-α (P<0.05). The Spearman's rank correlation analysis showed that at the genus level, the relative abundance of Ruminococcus, Alistipes, and Parasutterella in the sepsis group was negatively correlated with the levels of WBC, CRP, and IL-6 (P<0.05); the relative abundance of Enterococcus was positively correlated with the CRP level (P<0.01); the relative abundance of Streptococcus and Staphylococcus was positively correlated with the levels of CRP and IL-6 (P<0.05); the relative abundance of Streptococcus was positively correlated with WBC (P<0.05).

CONCLUSIONS

Intestinal flora disturbance is observed in children with sepsis, and its characteristics vary with the severity of the disease. The structural changes of intestinal flora are correlated with inflammatory response in children with sepsis.

Gynostemma pentaphyllum Extract Alleviates NASH in Mice: Exploration of Inflammation and Gut Microbiota

NASH (non-alcoholic steatohepatitis) is a severe liver disease characterized by hepatic chronic inflammation that can be associated with the gut microbiota. In this study, we explored the therapeutic effect of Gynostemma pentaphyllum extract (GPE), a Chinese herbal extract, on methionine- and choline-deficient (MCD) diet-induced NASH mice. Based on the peak area, the top ten compounds in GPE were hydroxylinolenic acid, rutin, hydroxylinoleic acid, vanillic acid, methyl vanillate, quercetin, pheophorbide A, protocatechuic acid, aurantiamide acetate, and iso-rhamnetin. We found that four weeks of GPE treatment alleviated hepatic confluent zone inflammation, hepatocyte lipid accumulation, and lipid peroxidation in the mouse model. According to the 16S rRNA gene V3-V4 region sequencing of the colonic contents, the gut microbiota structure of the mice was significantly changed after GPE supplementation. Especially, GPE enriched the abundance of potentially beneficial bacteria such as Akkerrmansia and decreased the abundance of opportunistic pathogens such as Klebsiella. Moreover, RNA sequencing revealed that the GPE group showed an anti-inflammatory liver characterized by the repression of the NF-kappa B signaling pathway compared with the MCD group. Ingenuity Pathway Analysis (IPA) also showed that GPE downregulated the pathogen-induced cytokine storm pathway, which was associated with inflammation. A high dose of GPE (HGPE) significantly downregulated the expression levels of the tumor necrosis factor-α (TNF-α), myeloid differentiation factor 88 (Myd88), cluster of differentiation 14 (CD14), and Toll-like receptor 4 (TLR4) genes, as verified by real-time quantitative PCR (RT-qPCR). Our results suggested that the therapeutic potential of GPE for NASH mice may be related to improvements in the intestinal microenvironment and a reduction in liver inflammation.

Insights into the Mechanisms of Action of Akkermansia muciniphila in the Treatment of Non-Communicable Diseases

This comprehensive review delineates the extensive roles of Akkermansia muciniphila in various health domains, spanning from metabolic and inflammatory diseases to neurodegenerative disorders. A. muciniphila, known for its ability to reside in the mucous layer of the intestine, plays a pivotal role in maintaining gut integrity and interacting with host metabolic processes. Its influence extends to modulating immune responses and potentially easing symptoms across several non-communicable diseases, including obesity, diabetes, inflammatory bowel disease, and cancer. Recent studies highlight its capacity to interact with the gut-brain axis, suggesting a possible impact on neuropsychiatric conditions. Despite the promising therapeutic potential of A. muciniphila highlighted in animal and preliminary human studies, challenges remain in its practical application due to stability and cultivation issues. However, the development of pasteurized forms and synthetic mediums offers new avenues for its use in clinical settings, as recognized by regulatory bodies like the European Food Safety Authority. This narrative review serves as a crucial resource for understanding the broad implications of A. muciniphila across different health conditions and its potential integration into therapeutic strategies.

Toll-like receptors in health and disease

Toll-like receptors (TLRs) are inflammatory triggers and belong to a family of pattern recognition receptors (PRRs) that are central to the regulation of host protective adaptive immune responses. Activation of TLRs in innate immune myeloid cells directs lymphocytes to produce the most appropriate effector responses to eliminate infection and maintain homeostasis of the body's internal environment. Inappropriate TLR stimulation can lead to the development of general autoimmune diseases as well as chronic and acute inflammation, and even cancer. Therefore, TLRs are expected to be targets for therapeutic treatment of inflammation-related diseases, autoimmune diseases, microbial infections, and human cancers. This review summarizes the recent discoveries in the molecular and structural biology of TLRs. The role of different TLR signaling pathways in inflammatory diseases, autoimmune diseases such as diabetes, cardiovascular diseases, respiratory diseases, digestive diseases, and even cancers (oral, gastric, breast, colorectal) is highlighted and summarizes new drugs and related clinical treatments in clinical trials, providing an overview of the potential and prospects of TLRs for the treatment of TLR-related diseases.

Paeoniflorin confers ferroptosis resistance by regulating the gut microbiota and its metabolites in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is closely related to ferroptosis, a new type of cell death that mainly manifests as intracellular iron accumulation and lipid peroxidation. Paeoniflorin (PA) helps to improve impaired glucose tolerance, influences the distribution of the intestinal flora, and induces significant resistance to ferroptosis in several models. In this study, we found that PA improved cardiac dysfunction in mice with DCM by alleviating myocardial damage, resisting oxidative stress and ferroptosis, and changing the community composition and structure of the intestinal microbiota. Metabolomics analysis revealed that PA-treated fecal microbiota transplantation affected metabolites in DCM mice. Based on in vivo and in vitro experiments, 11,12-epoxyeicosatrienoic acid (11,12-EET) may serve as a key contributor that mediates the cardioprotective and antiferroptotic effects of PA-treated fecal microbiota transplantation (FMT) in DCM mice.NEW & NOTEWORTHY This study demonstrated for the first time that paeoniflorin (PA) exerts protective effects in diabetic cardiomyopathy mice by alleviating myocardial damage, resisting ferroptosis, and changing the community composition and structure of the intestinal microbiota, and 11,12-epoxyeicosatrienoic acid (11,12-EET) may serve as a key contributor in its therapeutic efficacy.

LCN2 and ELANE overexpression induces sepsis

Sepsis is a syndrome characterized by a systemic inflammatory response due to the invasion of pathogenic microorganisms. The relationship between Lipocalin-2 (LCN2), elastase, neutrophil expressed (ELANE) and sepsis remains unclear. The sepsis datasets GSE137340 and GSE154918 profiles were downloaded from gene expression omnibus generated from GPL10558. Batch normalization, differentially expressed Genes (DEGs) screening, weighted gene co-expression network analysis (WGCNA), functional enrichment analysis, Gene Set Enrichment Analysis (GSEA), immune infiltration analysis, construction and analysis of protein-protein interaction (PPI) networks, Comparative Toxicogenomics Database (CTD) analysis were performed. Gene expression heatmaps were generated. TargetScan was used to screen miRNAs of DEGs. 328 DEGs were identified. According to Gene Ontology (GO), in the Biological Process analysis, they were mainly enriched in immune response, apoptosis, inflammatory response, and immune response regulation signaling pathways. In cellular component analysis, they were mainly enriched in vesicles, cytoplasmic vesicles, and secretory granules. In Molecular Function analysis, they were mainly concentrated in hemoglobin binding, Toll-like receptor binding, immunoglobulin binding, and RAGE receptor binding. In Kyoto Encyclopedia of Genes and Genomes (KEGG), they were mainly enriched in NOD-like receptor signaling pathway, Toll-like receptor signaling pathway, TNF signaling pathway, P53 signaling pathway, and legionellosis. Seventeen modules were generated. The PPI network identified 4 core genes (MPO, ELANE, CTSG, LCN2). Gene expression heatmaps revealed that core genes (MPO, ELANE, CTSG, LCN2) were highly expressed in sepsis samples. CTD analysis found that MPO, ELANE, CTSG and LCN2 were associated with sepsis, peritonitis, meningitis, pneumonia, infection, and inflammation. LCN2 and ELANE are highly expressed in sepsis and may serve as molecular targets.

Function and therapeutic prospects of next-generation probiotic Akkermansia muciniphila in infectious diseases

Akkermansia muciniphila is a gram-negative bacterium that colonizes the human gut, making up 3-5% of the human microbiome. A. muciniphila is a promising next-generation probiotic with clinical application prospects. Emerging studies have reported various beneficial effects of A. muciniphila including anti-cancer, delaying aging, reducing inflammation, improving immune function, regulating nervous system function, whereas knowledge on its roles and mechanism in infectious disease is currently unclear. In this review, we summarized the basic characteristics, genome and phenotype diversity, the influence of A. muciniphila and its derived components on infectious diseases, such as sepsis, virus infection, enteric infection, periodontitis and foodborne pathogen induced infections. We also provided updates on mechanisms how A. muciniphila protects intestinal barrier integrity and modulate host immune response. In summary, we believe that A. muciniphila is a promising therapeutic probiotic that may be applied for the treatment of a variety of infectious diseases.

Akkermansia muciniphila in infectious disease: A new target for this next-generation probiotic?

The common gastrointestinal commensal Akkermansia muciniphila is a mucin-degrading bacterium that is greatly reduced in individuals consuming a high-fat diet. Increasing evidence from a variety of clinical and pre-clinical studies suggests that oral supplementation with Akkermansia can improve metabolic health and moderate systemic inflammation. We and others have demonstrated a role for Akkermansia administration in protection against infectious disease and the outcome from sepsis. Very recent studies have indicated the molecular mechanisms by which A. muciniphila may interact with the host to influence systemic immune-regulation and control of microbial pathogenesis. Here we consider recent studies which demonstrate the efficacy of this potential next-generation probiotic in animal models of Salmonella Typhimurium, Listeria monocytogenes and Clostridioides difficile as well as influenza virus and phlebovirus. The potential mechanisms by which A. muciniphila may influence local and systemic immune responses are discussed.

Akkermansia muciniphila - friend or foe in colorectal cancer?

Akkermansia muciniphila is a gram-negative anaerobic bacterium, which represents a part of the commensal human microbiota. Decline in the abundance of A. muciniphila among other microbial species in the gut correlates with severe systemic diseases such as diabetes, obesity, intestinal inflammation and colorectal cancer. Due to its mucin-reducing and immunomodulatory properties, the use of probiotics containing Akkermansia sp. appears as a promising approach to the treatment of metabolic and inflammatory diseases. In particular, a number of studies have focused on the role of A. muciniphila in colorectal cancer. Of note, the results of these studies in mice are contradictory: some reported a protective role of A. muciniphila in colorectal cancer, while others demonstrated that administration of A. muciniphila could aggravate the course of the disease resulting in increased tumor burden. More recent studies suggested the immunomodulatory effect of certain unique surface antigens of A. muciniphila on the intestinal immune system. In this Perspective, we attempt to explain how A. muciniphila contributes to protection against colorectal cancer in some models, while being pathogenic in others. We argue that differences in the experimental protocols of administration of A. muciniphila, as well as viability of bacteria, may significantly affect the results. In addition, we hypothesize that antigens presented by pasteurized bacteria or live A. muciniphila may exert distinct effects on the barrier functions of the gut. Finally, A. muciniphila may reduce the mucin barrier and exerts combined effects with other bacterial species in either promoting or inhibiting cancer development.