Good Bug, Bad Bug: Breaking through Microbial Stereotypes

Dipeptide metabolite, glutamyl-glutamate mediates microbe-host interaction to boost spermatogenesis

The decrease in sperm count and infertility is a global issue that remains unresolved. By screening environmental bacterial isolates, we have found that a novel lactic acid bacterium, Lactiplantibacillus plantarum SNI3, increased testis size, testosterone levels, sperm count, sexual activity and fertility in mice that have consumed the bacteria for four weeks. The abundance of L. plantarum in the colon microbiome was positively associated with sperm count. Fecal microbiota transplantation (FMT) from L. plantarum SNI3-dosed mice improved testicular functions in microbiome-attenuated recipient animals. To identify mediators that confer pro-reproductive effects on the host, untargeted in situ mass spectrometry metabolomics was performed on testis samples of L. plantarum SNI3-treated and control mice. Enrichment pathway analysis revealed several perturbed metabolic pathways in the testis of treated mice. Within the testis, a dipeptide, glutamyl-glutamate (GluGlu) was the most upregulated metabolite following L. plantarum SNI3 administration. To validate the pro-reproductive feature of GluGlu, systemic and local injections of the dipeptide have been performed. γ-GluGlu increased sperm count but had no effect on testosterone. These findings highlight the role of γ-GluGlu in mediating spermatogenetic effects of L. plantarum on the male mouse host and -following relevant human clinical trials- may provide future tools for treating certain forms of male infertility.

Long-Term Exposure to Polystyrene Microspheres and High-Fat Diet-Induced Obesity in Mice: Evaluating a Role for Microbiota Dysbiosis

BACKGROUND

Microplastics (MPs) have become a global environmental problem, emerging as contaminants with potentially alarming consequences. However, long-term exposure to polystyrene microspheres (PS-MS) and its effects on diet-induced obesity are not yet fully understood.

OBJECTIVES

We aimed to investigate the effect of PS-MS exposure on high-fat diet (HFD)-induced obesity and underlying mechanisms.

METHODS

In the present study, C57BL/6J mice were fed a normal diet (ND) or a HFD in the absence or presence of PS-MS via oral administration for 8 wk. Antibiotic depletion of the microbiota and fecal microbiota transplantation (FMT) were performed to assess the influence of PS-MS on intestinal microbial ecology. We performed 16S rRNA sequencing to dissect microbial discrepancies and investigated the dysbiosis-associated intestinal integrity and inflammation in serum.

RESULTS

Compared with HFD mice, mice fed the HFD with PS-MS exhibited higher body weight, liver weight, metabolic dysfunction-associated steatotic liver disease (MASLD) activity scores, and mass of white adipose tissue, as well as higher blood glucose and serum lipid concentrations. Furthermore, 16S rRNA sequencing of the fecal microbiota revealed that mice fed the HFD with PS-MS had greater α -diversity and greater relative abundances of Lachnospiraceae, Oscillospiraceae, Bacteroidaceae, Akkermansiaceae, Marinifilaceae, Deferribacteres, and Desulfovibrio, but lower relative abundances of Atopobiaceae, Bifidobacterium, and Parabacteroides. Mice fed the HFD with PS-MS exhibited lower expression of MUC2 mucin and higher levels of lipopolysaccharide and inflammatory cytokines [tumor necrosis factor-α (TNF-α ), interleukin-6 (IL-6), IL-1β , and IL-17A] in serum. Correlation analyses revealed that differences in the microbial flora of mice exposed to PS-MS were associated with obesity. Interestingly, microbiota-depleted mice did not show the same PS-MS-associated differences in Muc2 and Tjp1 expression in the distal colon, expression of inflammatory cytokines in serum, or obesity outcomes between HFD and HFD + PS-MS. Importantly, transplantation of feces from HFD + PS-MS mice to microbiota-depleted HFD-fed mice resulted in a lower expression of mucus proteins, higher expression of inflammatory cytokines, and obesity outcomes, similar to the findings in HFD + PS-MS mice.

CONCLUSIONS

Our findings provide a new gut microbiota-driven mechanism for PS-MS-induced obesity in HFD-fed mice, suggesting the need to reevaluate the adverse health effects of MPs commonly found in daily life, particularly in susceptible populations. https://doi.org/10.1289/EHP13913.

The influence of aging and the microbiome in multiple sclerosis and other neurologic diseases

The human gut microbiome is well-recognized as a key player in maintaining health. However, it is a dynamic entity that changes across the lifespan. How the microbial changes that occur in later decades of life shape host health or impact age-associated inflammatory neurological diseases such as multiple sclerosis (MS) is still unclear. Current understanding of the aging gut microbiome is largely limited to cross-sectional observational studies. Moreover, studies in humans are limited by confounding host-intrinsic and extrinsic factors that are not easily disentangled from aging. This review provides a comprehensive summary of existing literature on the aging gut microbiome and its known relationships with neurological diseases, with a specific focus on MS. We will also discuss preclinical animal models and human studies that shed light on the complex microbiota-host interactions that have the potential to influence disease pathology and progression in aging individuals. Lastly, we propose potential avenues of investigation to deconvolute features of an aging microbiota that contribute to disease, or alternatively promote health in advanced age.

Diet-driven differential response of Akkermansia muciniphila modulates pathogen susceptibility

The erosion of the colonic mucus layer by a dietary fiber-deprived gut microbiota results in heightened susceptibility to an attaching and effacing pathogen, Citrobacter rodentium. Nevertheless, the questions of whether and how specific mucolytic bacteria aid in the increased pathogen susceptibility remain unexplored. Here, we leverage a functionally characterized, 14-member synthetic human microbiota in gnotobiotic mice to deduce which bacteria and functions are responsible for the pathogen susceptibility. Using strain dropouts of mucolytic bacteria from the community, we show that Akkermansia muciniphila renders the host more vulnerable to the mucosal pathogen during fiber deprivation. However, the presence of A. muciniphila reduces pathogen load on a fiber-sufficient diet, highlighting the context-dependent beneficial effects of this mucin specialist. The enhanced pathogen susceptibility is not owing to altered host immune or pathogen responses, but is driven by a combination of increased mucus penetrability and altered activities of A. muciniphila and other community members. Our study provides novel insights into the mechanisms of how discrete functional responses of the same mucolytic bacterium either resist or enhance enteric pathogen susceptibility.

The Potential Antinociceptive Effect and Mechanism of Cannabis sativa L. Extract on Paclitaxel-Induced Neuropathic Pain in Rats Uncovered by Multi-Omics Analysis

Cannabis sativa L. (hemp) is a herbaceous plant rich in cannabinoids with a long history of use in pain treatment. The most well-characterized cannabinoids, cannabidiol (CBD) and Δ9-tetrahydrocannabinol (Δ9-THC), garnered much attention in chemotherapy-induced peripheral neuropathy (CIPN) treatment. However, few studies have investigated the biological benefits and mechanism of hemp extract on CIPN. In the present study, hemp extract (JG) rich in cannabinoids was extracted by supercritical fluid carbon dioxide extraction (SFCE). The antinociceptive efficacy was evaluated using a paclitaxel-induced peripheral neuropathy (PIPN) rat model based on behavioral tests. Further omics-based approaches were applied to explore the potential mechanisms. The results showed that JG decreased mechanical allodynia, thermal hyperalgesia, and inflammatory cytokines in PIPN rats significantly. Transcriptome analysis identified seven key genes significantly regulated by JG in PIPN model rats, mainly related to the neuroactive ligand-receptor interaction pathway, PPAR signaling pathway, and cAMP signaling pathway. In metabolomic analysis, a total of 39 significantly altered metabolites were identified, mainly correlated with pentose and glucuronate interconversions and the glycerophospholipid metabolism pathway. Gut microbiota analysis suggested that increased community Lachnoclostridium and Lachnospiraceae_UCG-006 in PIPN rats can be reversed significantly by JG. In conclusion, hemp extract exhibited antinociceptive effects on PIPN. The analgesic mechanism was probably related to the regulation of inflammation, neuroactive ligand-receptor interaction pathway, sphingolipid metabolism, etc. This study provides novel insights into the functional interactions of Cannabis sativa L. extract on PIPN.

Opioid-induced dysbiosis of maternal gut microbiota during gestation alters offspring gut microbiota and pain sensitivity

There has been a rapid increase in neonates born with a history of prenatal opioid exposure. How prenatal opioid exposure affects pain sensitivity in offspring is of interest, as this may perpetuate the opioid epidemic. While few studies have reported hypersensitivity to thermal pain, potential mechanisms have not been described. This study posits that alterations in the gut microbiome may underly hypersensitivity to pain in prenatally methadone-exposed 3-week-old male offspring, which were generated using a mouse model of prenatal methadone exposure. Fecal samples collected from dams and their offspring were subjected to 16s rRNA sequencing. Thermal and mechanical pain were assessed using the tail flick and Von Frey assays. Transcriptomic changes in whole brain samples of opioid or saline-exposed offspring were investigated using RNA-sequencing, and midbrain sections from these animals were subjected to qPCR profiling of genes related to neuropathic and inflammatory pain pathways. Prenatal methadone exposure increased sensitivity to thermal and mechanical pain and elevated serum levels of IL-17a. Taxonomical analysis revealed that prenatal methadone exposure resulted in significant alterations in fecal gut microbiota composition, including depletion of Lactobacillus, Bifidobacterium, and Lachnospiracea sp and increased relative abundance of Akkermansia, Clostridium sensu stricto 1, and Lachnoclostridium. Supplementation of the probiotic VSL#3 in dams rescued hypersensitivity to thermal and mechanical pain in prenatally methadone-exposed offspring. Similarly, cross-fostering prenatally methadone-exposed offspring to control dams also attenuated hypersensitivity to thermal pain in opioid-exposed offspring. Modulation of the maternal and neonatal gut microbiome with probiotics resulted in transcriptional changes in genes related to neuropathic and immune-related signaling in whole brain and midbrain samples of prenatally methadone-exposed offspring. Together, our work provides compelling evidence of the gut-brain-axis in mediating pain sensitivity in prenatally opioid-exposed offspring.

Akkermansia muciniphila MucT attenuates sodium valproate-induced hepatotoxicity and upregulation of Akkermansia muciniphila in rats

In the previous study, we found that the oral sodium valproate (SVP) increased the relative abundance of Akkermansia muciniphila (A. muciniphila) in rats, and plasma aspartate transaminase (AST) and alanine aminotransferase (ALT) activities were positively correlated with A. muciniphila levels. This study aimed to further investigate the role of A. muciniphila in SVP-induced hepatotoxicity by orally supplementing rats with the representative strain of A. muciniphila, A. muciniphila MucT. Additionally, the fresh faeces were incubated anaerobically with SVP to investigate the effect of SVP on faecal A. muciniphila in the absence of host influence. Results showed that A. muciniphila MucT ameliorated the hepatotoxicity and upregulation of A. muciniphila induced by SVP. SVP also induced a noteworthy elevation of A. muciniphila level in vitro, supporting the observation in vivo. Therefore, we speculate that A. muciniphila MucT may be a potential therapeutic strategy for SVP-induced hepatotoxicity. In addition, the increased A. muciniphila induced by SVP may differ from A. muciniphila MucT, but further evidence is needed. These findings provide new insights into the relationships between A. muciniphila and SVP-induced hepatotoxicity, highlighting the potential for different A. muciniphila strains to have distinct or even opposing effects on SVP-induced hepatotoxicity.

Akkermansia muciniphila and Alcohol-Related Liver Diseases. A Systematic Review

SCOPE

Akkermansia muciniphila (A. muciniphila) are Gram negative commensal bacteria, degrading mucin in the intestinal mucosa, modulating intestinal permeability and inflammation in the digestive tract, liver, and blood. Some components can promote the relative abundance of A. muciniphila in the gut microbiota, but lower levels of A. muciniphila are more commonly found in people with obesity, diabetes, metabolic syndromes, or inflammatory digestive diseases. Over-intake of ethanol can also induce a decrease of A. muciniphila, associated with dysregulation of microbial metabolite production, impaired intestinal permeability, induction of chronic inflammation, and production of cytokines.

METHODS AND RESULTS

Using a PRISMA search strategy, a review is performed on the bacteriological characteristics of A. muciniphila, the factors capable of modulating its relative abundance in the digestive tract and its probiotic use in alcohol-related liver diseases (alcoholic hepatitis, cirrhosis, hepatocellular carcinoma, hepatic transplantation, partial hepatectomy).

CONCLUSION

Several studies have shown that supplementation with A. muciniphila can improve ethanol-related hepatic pathologies, and highlight the interest in using this bacterial species as a probiotic.

Diet-driven differential response of Akkermansia muciniphila modulates pathogen susceptibility

The erosion of the colonic mucus layer by a dietary fiber-deprived gut microbiota results in heightened susceptibility to an attaching and effacing pathogen, Citrobacter rodentium. Nevertheless, the questions of whether and how specific mucolytic bacteria aid in the increased pathogen susceptibility remain unexplored. Here, we leverage a functionally characterized, 14-member synthetic human microbiota in gnotobiotic mice to deduce which bacteria and functions are responsible for the pathogen susceptibility. Using strain dropouts of mucolytic bacteria from the community, we show that Akkermansia muciniphila renders the host more vulnerable to the mucosal pathogen during fiber deprivation. However, the presence of A. muciniphila reduces pathogen load on a fiber-sufficient diet, highlighting the context-dependent beneficial effects of this mucin specialist. The enhanced pathogen susceptibility is not owing to altered host immune or pathogen responses, but is driven by a combination of increased mucus penetrability and altered activities of A. muciniphila and other community members. Our study provides novel insights into the mechanisms of how discrete functional responses of the same mucolytic bacterium either resist or enhance enteric pathogen susceptibility.

CHD8 regulates gut epithelial cell function and affects autism-related behaviors through the gut-brain axis

Autism is a neurodevelopmental disorder characterized by early-onset social behavioral deficits and repetitive behaviors. Chromodomain helicase DNA-binding protein (CHD8) is among the genes most strongly associated with autism. In addition to the core behavioral symptoms of autism, affected individuals frequently present with gastrointestinal symptoms that are also common among individuals harboring mutations in the gene encoding CHD8. However, little is known regarding the mechanisms whereby CHD8 affects gut function. In addition, it remains unknown whether gastrointestinal manifestations contribute to the behavioral phenotypes of autism. The current study found that mice haploinsufficient for the large isoform of Chd8 (Chd8L) exhibited increased intestinal permeability, transcriptomic dysregulation in gut epithelial cells, reduced tuft cell and goblet cell counts in the gut, and an overall increase in microbial load. Gut epithelial cell-specific Chd8 haploinsufficiency was associated with increased anxiety-related behaviors together with a decrease in tuft cell numbers. Antibiotic treatment of Chd8L haploinsufficient mice attenuated social behavioral deficits. Together, these results suggest Chd8 as a key determinant of autism-related gastrointestinal deficits, while also laying the ground for future studies on the link between GI deficits and autism-related behaviors.

Maternal diet and gut microbiome composition modulate early-life immune development

In early life, the intestinal mucosa and immune system undergo a critical developmental process to contain the expanding gut microbiome while promoting tolerance toward commensals, yet the influence of maternal diet and microbial composition on offspring immune maturation remains poorly understood. We colonized germ-free mice with a consortium of 14 strains, fed them a standard fiber-rich chow or a fiber-free diet, and then longitudinally assessed offspring development during the weaning period. Unlike pups born to dams fed the fiber-rich diet, pups of fiber-deprived dams demonstrated delayed colonization with Akkermansia muciniphila, a mucin-foraging bacterium that can also use milk oligosaccharides. The pups of fiber-deprived dams exhibited an enrichment of colonic transcripts corresponding to defense response pathways and a peak in Il22 expression at weaning. Removal of A. muciniphila from the community, but maintenance on the fiber-rich diet, was associated with reduced proportions of RORγt-positive innate and adaptive immune cell subsets. Our results highlight the potent influence of maternal dietary fiber intake and discrete changes in microbial composition on the postnatal microbiome assemblage and early immune development.

Neurodegenerative and Neurodevelopmental Diseases and the Gut-Brain Axis: The Potential of Therapeutic Targeting of the Microbiome

The human gut microbiome contains the largest number of bacteria in the body and has the potential to greatly influence metabolism, not only locally but also systemically. There is an established link between a healthy, balanced, and diverse microbiome and overall health. When the gut microbiome becomes unbalanced (dysbiosis) through dietary changes, medication use, lifestyle choices, environmental factors, and ageing, this has a profound effect on our health and is linked to many diseases, including lifestyle diseases, metabolic diseases, inflammatory diseases, and neurological diseases. While this link in humans is largely an association of dysbiosis with disease, in animal models, a causative link can be demonstrated. The link between the gut and the brain is particularly important in maintaining brain health, with a strong association between dysbiosis in the gut and neurodegenerative and neurodevelopmental diseases. This link suggests not only that the gut microbiota composition can be used to make an early diagnosis of neurodegenerative and neurodevelopmental diseases but also that modifying the gut microbiome to influence the microbiome-gut-brain axis might present a therapeutic target for diseases that have proved intractable, with the aim of altering the trajectory of neurodegenerative and neurodevelopmental diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, autism spectrum disorder, and attention-deficit hyperactivity disorder, among others. There is also a microbiome-gut-brain link to other potentially reversible neurological diseases, such as migraine, post-operative cognitive dysfunction, and long COVID, which might be considered models of therapy for neurodegenerative disease. The role of traditional methods in altering the microbiome, as well as newer, more novel treatments such as faecal microbiome transplants and photobiomodulation, are discussed.

T-cell activation Rho GTPase-activating protein maintains intestinal homeostasis by regulating intestinal T helper cells differentiation through the gut microbiota

Common variants of the T-cell activation Rho GTPase-activating protein (TAGAP) are associated with the susceptibility to human inflammatory bowel diseases (IBDs); however, the underlying mechanisms are still unknown. Here, we show that TAGAP deficiency or TAGAP expression downregulation caused by TAGAP gene polymorphism leads to decreased production of antimicrobial peptides (AMPs), such as reg3g, which subsequently causes dysregulation of the gut microbiota, which includes Akkermansia muciniphila and Bacteroides acidifaciens strains. These two strains can polarize T helper cell differentiation in the gut, and aggravate systemic disease associated with the dextran sodium sulfate-induced (DSS) disease's phenotype in mice. More importantly, we demonstrated that recombinant reg3g protein or anti-p40 monoclonal antibody exerted therapeutic effects for the treatment of DSS-induced colitis in wild-type and TAGAP-deficient mice, suggesting that they are potential medicines for human IBD treatment, and they may also have a therapeutic effect for the patients who carry the common variant of TAGAP rs212388.

Influencing Factors of Stereotypes on Wastewater Treatment Plants- Case Study of 9 Wastewater Treatment Plants in Xi'an, China

As an indispensable part of cities, wastewater treatment plants play an important role in environmental protection and urbanization. However, the promotion of wastewater treatment plants has been consistently hindered by residents' negative stereotypes and rejections, which is called "Not-In-My-Back-Yard" (NIMBY) effect. This study collected the first-hand data with the residents residing within 3 kilometers of 9 wastewater treatment plants in Xi'an, China through a survey. Keyword co-occurrence network analysis was conducted and the results illustrate that residents have stereotypes toward wastewater treatment plants. There are two types of residents' stereotypes toward wastewater treatment plants: positive and negative. The positive stereotypes of wastewater treatment plants in turn can be subdivided into the three categories of treatment technologies, treatment results, and social impacts. But the negative stereotypes didn't demonstrate meaningful categories. We also tried to identify the influencing factors that cause residents' stereotypes. The distance from residents' residence to the wastewater treatment plants has impacts on the stereotypes of residents' who reside within 1000 meters of the wastewater treatment plant: the farther from the wastewater treatment plants their residence is, the more positive their stereotypes are. We also found that the more educated the participants are, the more positive stereotypes of wastewater treatment plants they have. Moreover, residents' stereotypes toward wastewater treatment plants are more influenced by formal education. Non-formal education and informal learning probably have less influence on the promotion of wastewater treatment plants. Therefore, we propose to incorporate environmental education for sustainable development into formal education to increase residents' acceptance of wastewater treatment plants.

Two unique biological response-modifier glucans beneficially regulating gut microbiota and faecal metabolome in a non-alcoholic steatohepatitis animal model, with potential applications in human health and disease

OBJECTIVE

The gut microbiome and its metabolites are influenced by age and stress and reflect the metabolism and health of the immune system. We assessed the gut microbiota and faecal metabolome in a static animal model of non-alcoholic steatohepatitis (NASH).

DESIGN

This model was subjected to the following treatments: reverse osmosis water, AFO-202, N-163, AFO-202+N-163 and telmisartan treatment. Faecal samples were collected at 6 and 9 weeks of age. The gut microbiome was analysed using 16S ribosomal RNA sequences acquired by next-generation sequencing, and the faecal metabolome was analysed using gas chromatography-mass spectrometry.

RESULTS

Gut microbial diversity increased greatly in the AFO-202+N-163 group. Postintervention, the abundance of Firmicutes decreased, whereas that of Bacteroides increased and was the highest in the AFO-202+N-163 group. The decrease in the abundance of Enterobacteriaceae and other Firmicutes and the abundance of Turicibacter and Bilophila were the highest in the AFO-202 and N-163 groups, respectively. Lactobacillus abundance was highest in the AFO-202+N-163 group. The faecal metabolite spermidine, which is beneficial against inflammation and NASH, was significantly decreased (p=0.012) in the N-163 group. Succinic acid, which is beneficial in neurodevelopmental and neurodegenerative diseases, was increased in the AFO-202 group (p=0.06). The decrease in fructose was the highest in the N-163 group (p=0.0007). Isoleucine and Leucine decreased with statistical significance (p=0.004 and 0.012, respectively), and tryptophan also decreased (p=0.99), whereas ornithine, which is beneficial against chronic immune-metabolic-inflammatory pathologies, increased in the AFO-202+N-163 group.

CONCLUSION

AFO-202 treatment in mice is beneficial against neurodevelopmental and neurodegenerative diseases, and has prophylactic potential against metabolic conditions. N-163 treatment exerts anti-inflammatory effects against organ fibrosis and neuroinflammation. In combination, these compounds exhibit anticancer activity.

A previously uncharacterized O-glycopeptidase from Akkermansia muciniphila requires the Tn-antigen for cleavage of the peptide bond

Akkermansia muciniphila is key member of the human gut microbiota, impacting many features of host health. A major characteristic of this bacterium is its interaction with host mucin, which is abundant in the gut environment, and its ability to metabolize mucin as a nutrient source. The machinery deployed by A. muciniphila to enable this interaction appears to be extensive and sophisticated, yet it is incompletely defined. The uncharacterized protein AMUC_1438 is encoded by a gene that was previously shown to be upregulated when the bacterium is grown on mucin. This uncharacterized protein has features suggestive of carbohydrate-recognition and peptidase activity, which led us to hypothesize that it has a role in mucin depolymerization. Here we provide structural and functional support for the assignment of AMUC_1438 as a unique O-glycopeptidase with mucin degrading capacity. O-glycopeptidase enzymes recognize glycans but hydrolyze the peptide backbone and are common in host-adapted microbes that colonize or invade mucus layers. Structural, kinetic, and mutagenic analyses point to a metzincin metalloprotease catalytic motif but specific recognition of a GalNAc residue α-linked to serine or threonine (i.e. the Tn-antigen) within the AMUC_1438 active site. The enzyme catalyzes hydrolysis of the bond immediately N-terminal to the glycosylated residue. Additional modelling analyses suggest the presence of a carbohydrate-binding module that may assist in substrate recognition. We anticipate that these results will be fundamental to a wider understanding of the O-glycopeptidase class of enzymes and how they may contribute to host-adaptation.

Exploring the potential antidepressant mechanisms of puerarin: Anti-inflammatory response via the gut-brain axis

BACKGROUND

Puerarin has been shown to have a good antidepressant effect, and our previous study found that it can remedy stress-induced dysbiosis. However, its gut microbiota-related mechanism has not been fully elucidated. Therefore, this study aimed to investigate the potential link between puerarin on gut microbiota and inflammatory responses in depressed rats.

METHODS

A chronic unpredictable mild stress (CUMS) rat model of depression was established, open field test (OFT), sucrose preference test (SPT) and forced swimming test (FST) were used to evaluate its antidepressant effect. 16S rRNA sequencing was performed to identify the rat fecal microflora. At the same time, inflammatory cytokines, colonic histopathological changes, and brain-derived neurotrophic factor (BDNF), nuclear factor kappa-B (NF-κB), inhibitor a of NF-κB (IκB-α) protein expression were detected.

RESULTS

Puerarin attenuated CUMS-induced depressive-like behavior and gut microbiota dysregulation in rats, significantly reducing the abundance of harmful bacteria such as Desulfovibrio, Verrucomicrobiae, and Verrucomicrobia. In addition, puerarin can also reduce the pro-inflammatory factors and increase the level of anti-inflammatory factors in depressed rats, improve the damaged colon tissue, enhance the expression of BDNF and IκB-α in the hippocampus and inhibit the expression of NF-κB.

LIMITATIONS

Direct evidence that puerarin improves depressive-like behaviors via gut microbiota is lacking.

CONCLUSION

The underlying mechanism of puerarin's antidepressant-like effect is closely related to the bidirectional communication of the microbiota-gut-brain axis by regulating the inflammatory response.

Nonalcoholic Fatty Liver Disease and the Gut-Liver Axis: Exploring an Undernutrition Perspective

Nonalcoholic fatty liver disease (NAFLD) is a chronic condition affecting one quarter of the global population. Although primarily linked to obesity and metabolic syndrome, undernutrition and the altered (dysbiotic) gut microbiome influence NAFLD progression. Both undernutrition and NAFLD prevalence are predicted to considerably increase, but how the undernourished gut microbiome contributes to hepatic pathophysiology remains far less studied. Here, we present undernutrition conditions with fatty liver features, including kwashiorkor and micronutrient deficiency. We then review the gut microbiota-liver axis, highlighting key pathways linked to NAFLD progression within both overnutrition and undernutrition. To conclude, we identify challenges and collaborative possibilities of emerging multiomic research addressing the pathology and treatment of undernourished NAFLD.

Host-microbial interactions in metabolic diseases: from diet to immunity

Growing evidence suggests that the gut microbiome is an important contributor to metabolic diseases. Alterations in microbial communities are associated with changes in lipid metabolism, glucose homeostasis, intestinal barrier functions, and chronic inflammation, all of which can lead to metabolic disorders. Therefore, the gut microbiome may represent a novel therapeutic target for obesity, type 2 diabetes, and nonalcoholic fatty liver disease. This review discusses how gut microbes and their products affect metabolic diseases and outlines potential treatment approaches via manipulation of the gut microbiome. Increasing our understanding of the interactions between the gut microbiome and host metabolism may help restore the healthy symbiotic relationship between them.

Microbiome-based therapeutics

Symbiotic microorganisms inhabiting the gastrointestinal tract promote health by decreasing susceptibility to infection and enhancing resistance to a range of diseases. In this Review, we discuss our increasing understanding of the impact of the microbiome on the mammalian host and recent efforts to culture and characterize intestinal symbiotic microorganisms that produce or modify metabolites that impact disease pathology. Manipulation of the intestinal microbiome has great potential to reduce the incidence and/or severity of a wide range of human conditions and diseases, and the biomedical research community now faces the challenge of translating our understanding of the microbiome into beneficial medical therapies. Our increasing understanding of symbiotic microbial species and the application of ecological principles and machine learning are providing exciting opportunities for microbiome-based therapeutics to progress from faecal microbiota transplantation to the administration of precisely defined and clinically validated symbiotic microbial consortia that optimize disease resistance.

A common fungicide tebuconazole promotes colitis in mice via regulating gut microbiota

As a common fungicide, tebuconazole are ubiquitous in the natural environment and poses many potential risks. In this study, we examined the effects of exposure to tebuconazole on colitis in mice and explored its underlying mechanism. Specifically, exposure to tebuconazole could cause structural damage and inflammatory cell infiltration in colon tissue, activate the expression of inflammation-related genes, disrupt the expression of barrier function-related genes, and induce the colonic inflammation in mice. Similarly, exposure to tebuconazole could also exacerbate DSS-induced colitis in mice. In addition, we found that tebuconazole also could change the composition of the gut microbiota. In particular, tebuconazole significantly increases the relative abundance of Akkermansia of mice. Moreover, tebuconazole resulted in metabolic profiles disorders of the serum, leading to significant changes in the relative contents of metabolites involving glycolipid metabolism and amino acid metabolism. Particularly, the results of the gut microbiota transplantation experiment showed that exposure to tebuconazole could induced colonic inflammation in mice in a gut microbiota-dependent manner. Taken together, these results indicated that tebuconazole could induce colitis in mice via regulating gut microbiota. Our findings strongly support the concept that the gut microbiota is a key trigger of inflammatory bowel disease caused by pesticide intake.

Different Types and Functional Effects of Probiotics on Human Health through Regulating Glucose Homeostasis

With the increasing improvement of people's living standards, hyperglycemia has become one of the most frequent diseases in the world. The current drug therapy may have some negative effects and even cause some complications. As one of the most popular functional ingredients, probiotic bacteria have been proven to play important roles in balancing the glucose homeostasis level in animal and human clinic trials. In this perspective, we sorted three types of probiotics, discussed probiotic safety evaluation, and listed the known probiotic functional foods that assist to control glucose homeostasis. Then, the further summarization of the mechanisms on how probiotic bacteria could regulate glucose homeostasis and the developing trend of probiotic functional foods were discussed.

An Osmotic Laxative Renders Mice Susceptible to Prolonged Clostridioides difficile Colonization and Hinders Clearance

Antibiotics are a major risk factor for Clostridioides difficile infections (CDIs) because of their impact on the microbiota. However, nonantibiotic medications such as the ubiquitous osmotic laxative polyethylene glycol 3350 (PEG 3350) also alter the microbiota. Clinicians also hypothesize that PEG helps clear C. difficile. But whether PEG impacts CDI susceptibility and clearance is unclear. To examine how PEG impacts susceptibility, we treated C57BL/6 mice with 5-day and 1-day doses of 15% PEG in the drinking water and then challenged the mice with C. difficile 630. We used clindamycin-treated mice as a control because they consistently clear C. difficile within 10 days postchallenge. PEG treatment alone was sufficient to render mice susceptible, and 5-day PEG-treated mice remained colonized for up to 30 days postchallenge. In contrast, 1-day PEG-treated mice were transiently colonized, clearing C. difficile within 7 days postchallenge. To examine how PEG treatment impacts clearance, we administered a 1-day PEG treatment to clindamycin-treated, C. difficile-challenged mice. Administering PEG to mice after C. difficile challenge prolonged colonization up to 30 days postchallenge. When we trained a random forest model with community data from 5 days postchallenge, we were able to predict which mice would exhibit prolonged colonization (area under the receiver operating characteristic curve [AUROC] = 0.90). Examining the dynamics of these bacterial populations during the postchallenge period revealed patterns in the relative abundances of Bacteroides, Enterobacteriaceae, Porphyromonadaceae, Lachnospiraceae, and Akkermansia that were associated with prolonged C. difficile colonization in PEG-treated mice. Thus, the osmotic laxative PEG rendered mice susceptible to C. difficile colonization and hindered clearance.

IMPORTANCE Diarrheal samples from patients taking laxatives are typically rejected for Clostridioides difficile testing. However, there are similarities between the bacterial communities from people with diarrhea and those with C. difficile infections (CDIs), including lower diversity than the communities from healthy patients. This observation led us to hypothesize that diarrhea may be an indicator of C. difficile susceptibility. We explored how osmotic laxatives disrupt the microbiota’s colonization resistance to C. difficile by administering a laxative to mice either before or after C. difficile challenge. Our findings suggest that osmotic laxatives disrupt colonization resistance to C. difficile and prevent clearance among mice already colonized with C. difficile. Considering that most hospitals recommend not performing C. difficile testing on patients taking laxatives, and laxatives are prescribed prior to administering fecal microbiota transplants via colonoscopy to patients with recurrent CDIs, further studies are needed to evaluate if laxatives impact microbiota colonization resistance in humans.

Microbial evolution and transitions along the parasite-mutualist continuum

Virtually all plants and animals, including humans, are home to symbiotic microorganisms. Symbiotic interactions can be neutral, harmful or have beneficial effects on the host organism. However, growing evidence suggests that microbial symbionts can evolve rapidly, resulting in drastic transitions along the parasite-mutualist continuum. In this Review, we integrate theoretical and empirical findings to discuss the mechanisms underpinning these evolutionary shifts, as well as the ecological drivers and why some host-microorganism interactions may be stuck at the end of the continuum. In addition to having biomedical consequences, understanding the dynamic life of microorganisms reveals how symbioses can shape an organism's biology and the entire community, particularly in a changing world.

A natural history museum visitor survey of perception, attitude and knowledge (PAK) of microbes and antibiotics

A kiosk-based survey at the American Museum of Natural History in New York City in 2016-2018 allowed us to assess public knowledge of antibiotics and public attitudes toward microbes in museum goers. Over 22,000 visitors from 172 countries and territories answered several carefully designed questions about microbes and antibiotics. These visitors also entered age, gender, and country demographic data that allowed for stratification along these demographic and geographic divisions. Because museum goers are likely to be better informed about these and other science-based topics, the results described here can set a potential upper bound for public knowledge on these topics. Surprisingly, the results of our analysis of museum goers' answers about microbes and antibiotics indicate a substantial lack of familiarity with both topics. For example, overall only about 50% of respondents can correctly identify penicillin as an antibiotic and less than 50% of museum visitors view microbes as beneficial. The results described here suggest that we are perhaps off target with our educational efforts in this area and that a major shift in approach toward more basic microbial topics is warranted in our educational efforts.

A kiosk survey of perception, attitudes and knowledge (PAK) of Australians concerning microbes, antibiotics, probiotics and hygiene

Issues addressed

To obtain a baseline of public perception, attitudes and knowledge (PAK) of Australians about microbes, antibiotics and hygiene like hand washing and use of probiotics.

Methods

Using a kiosk‐based survey method at the American Museum of Natural History (AMNH), we remotely assayed PAK of Australians through their interaction with the kiosk. The surveys we used had five and seven multiple answer questions and were analysed using standard comparative approaches. We also made comparisons based on gender and on age group for many of the questions.

Results

Our analyses indicate that there is a lack of general understanding of the role of microbes in everyday life among Australians. In addition, we detected some basic misunderstandings about antibiotics. While 80% of the respondents identified penicillin as an antibiotic, up to 30% of the respondents wrongly identified aspirin, Tylenol, valium and Benadryl as antibiotics. We also detected a general lack of knowledge about hand washing hygiene and probiotic use.

Conclusions

Our results from around 700 Australian respondents can serve as a baseline for further PAK assessment of Australians. PAK of Australians with respect to microbes and hand washing hygiene is poor therefore public education is needed. This study should stimulate a better roadmap for public education about microbes, antibiotics, probiotics and hygiene.

So what?

With the recent spread of SARS‐Cov2 and the ensuing Covid19 pandemic and the continuing rise in antimicrobial resistance, the need for assessment PAK of microbes and infectious disease has become acute.

Multi-omics: Opportunities for research on mechanism of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a burdensome global disease. In-depth understanding of its mechanism will help to optimize diagnosis and treatment, which reduces the burden. Multi-omics research has unparalleled advantages in contributing to the overall understanding of the mechanism of this chronic metabolic disease. In the past two decades, the study of multi-omics on T2DM-related intestinal flora perturbation and plasma dyslipidemia has shown tremendous potential and is expected to achieve major breakthroughs. The regulation of intestinal flora in diabetic patients has been confirmed by multiple studies. The use of metagenomics, 16S RNA sequencing, and metabolomics has comprehensively identified the overall changes in the intestinal flora and the metabolic disturbances that could directly or indirectly participate in the intestinal flora-host interactions. Lipidomics combined with other “omics” has characterized lipid metabolism disorders in T2DM. The combined application and cross-validation of multi-omics can screen for dysregulation in T2DM, which will provide immense opportunities to understand the mechanisms behind T2DM.

Increasing breast milk betaine modulates Akkermansia abundance in mammalian neonates and improves long-term metabolic health

Accelerated postnatal growth is a potentially modifiable risk factor for future obesity. To study how specific breast milk components contribute to early growth and obesity risk, we quantified one-carbon metabolism-related metabolites in human breast milk and found an inverse association between milk betaine content and infant growth. This association was replicated in an independent and geographically distinct cohort. To determine the potential role of milk betaine in modulating offspring obesity risk, we performed maternal betaine supplementation experiments in mice. Higher betaine intake during lactation increased milk betaine content in dams and led to lower adiposity and improved glucose homeostasis throughout adulthood in mouse offspring. These effects were accompanied by a transient increase in Akkermansia spp. abundance in the gut during early life and a long-lasting increase in intestinal goblet cell number. The link between breast milk betaine and Akkermansia abundance in the gut was also observed in humans, as infants exposed to higher milk betaine content during breastfeeding showed higher fecal Akkermansia muciniphila abundance. Furthermore, administration of A. muciniphila to mouse pups during the lactation period partially replicated the effects of maternal breast milk betaine, including increased intestinal goblet cell number, lower adiposity, and improved glucose homeostasis during adulthood. These data demonstrate a link between breast milk betaine content and long-term metabolic health of offspring.

Alterations in gut microbiota linked to provenance, sex, and chronic wasting disease in white-tailed deer (Odocoileus virginianus)

Chronic wasting disease (CWD) is a fatal, contagious, neurodegenerative prion disease affecting both free-ranging and captive cervid species. CWD is spread via direct or indirect contact or oral ingestion of prions. In the gastrointestinal tract, prions enter the body through microfold cells (M-cells), and the abundance of these cells can be influenced by the gut microbiota. To explore potential links between the gut microbiota and CWD, we collected fecal samples from farmed and free-ranging white-tailed deer (Odocoileus virginianus) around the Midwest, USA. Farmed deer originated from farms that were depopulated due to CWD. Free-ranging deer were sampled during annual deer harvests. All farmed deer were tested for CWD via ELISA and IHC, and we used 16S rRNA gene sequencing to characterize the gut microbiota. We report significant differences in gut microbiota by provenance (Farm 1, Farm 2, Free-ranging), sex, and CWD status. CWD-positive deer from Farm 1 and 2 had increased abundances of Akkermansia, Lachnospireacea UCG-010, and RF39 taxa. Overall, differences by provenance and sex appear to be driven by diet, while differences by CWD status may be linked to CWD pathogenesis.

Host gut microbiome and potential therapeutics in Gulf War Illness: A short review

AIMS

Since our troops had returned from the first Persian Gulf War in 1990-91, the veterans have reported chronic multisymptomatic illness widely referred to as Gulf War Illness (GWI). We aim to review the current directions of GWI pathology research in the context of chronic multisymptomatic illness and its possible gut microbiome targeted therapies. The veterans of Gulf War show symptoms of chronic fatigue, cognitive deficits, and a subsection report of gastrointestinal complications.

METHOD

Efforts of finding a suitable treatment regimen and clinical management remain a challenge. More recently, we have shown that the pathology is connected to alterations in the gut microbiome, and efforts of finding a suitable regimen for gut-directed therapeutics are underway. We discuss the various clinical interventions and summarize the possible effectiveness of gut-directed therapies such as the use of short-chain fatty acids (SCFA), phenolic compounds, and their metabolites, use of probiotics, and fecal microbiota transfer.

SIGNIFICANCE

The short review will be helpful to GWI researchers to expand their studies to the gut and find an effective treatment strategy for chronic multisymptomatic illness.

Genotypic and Phenotypic Diversity among Human Isolates of Akkermansia muciniphila

The mucophilic anaerobic bacterium Akkermansia muciniphila is a prominent member of the gastrointestinal (GI) microbiota and the only known species of the Verrucomicrobia phylum in the mammalian gut. A high prevalence of A. muciniphila in adult humans is associated with leanness and a lower risk for the development of obesity and diabetes. Four distinct A. muciniphila phylogenetic groups have been described, but little is known about their relative abundance in humans or how they impact human metabolic health. In this study, we isolated and characterized 71 new A. muciniphila strains from a cohort of children and adolescents undergoing treatment for obesity. Based on genomic and phenotypic analysis of these strains, we found several phylogroup-specific phenotypes that may impact the colonization of the GI tract or modulate host functions, such as oxygen tolerance, adherence to epithelial cells, iron and sulfur metabolism, and bacterial aggregation. In antibiotic-treated mice, phylogroups AmIV and AmII outcompeted AmI strains. In children and adolescents, AmI strains were most prominent, but we observed high variance in A. muciniphila abundance and single phylogroup dominance, with phylogroup switching occurring in a small subset of patients. Overall, these results highlight that the ecological principles determining which A. muciniphila phylogroup predominates in humans are complex and that A. muciniphila strain genetic and phenotypic diversity may represent an important variable that should be taken into account when making inferences as to this microbe's impact on its host's health.IMPORTANCE The abundance of Akkermansia muciniphila in the gastrointestinal (GI) tract is linked to multiple positive health outcomes. There are four known A. muciniphila phylogroups, yet the prevalence of these phylogroups and how they vary in their ability to influence human health is largely unknown. In this study, we performed a genomic and phenotypic analysis of 71 A. muciniphila strains and identified phylogroup-specific traits such as oxygen tolerance, adherence, and sulfur acquisition that likely influence colonization of the GI tract and differentially impact metabolic and immunological health. In humans, we observed that single Akkermansia phylogroups predominate at a given time but that the phylotype can switch in an individual. This collection of strains provides the foundation for the functional characterization of A. muciniphila phylogroup-specific effects on the multitude of host outcomes associated with Akkermansia colonization, including protection from obesity, diabetes, colitis, and neurological diseases, as well as enhanced responses to cancer immunotherapies.

Organoid-based Models to Study the Role of Host-microbiota Interactions in IBD

The gut microbiota appears to play a central role in health, and alterations in the gut microbiota are observed in both forms of inflammatory bowel disease [IBD], namely Crohn's disease and ulcerative colitis. Yet, the mechanisms behind host-microbiota interactions in IBD, especially at the intestinal epithelial cell level, are not yet fully understood. Dissecting the role of host-microbiota interactions in disease onset and progression is pivotal, and requires representative models mimicking the gastrointestinal ecosystem, including the intestinal epithelium, the gut microbiota, and immune cells. New advancements in organoid microfluidics technology are facilitating the study of IBD-related microbial-epithelial cross-talk, and the discovery of novel microbial therapies. Here, we review different organoid-based ex vivo models that are currently available, and benchmark their suitability and limitations for specific research questions. Organoid applications, such as patient-derived organoid biobanks for microbial screening and 'omics technologies, are discussed, highlighting their potential to gain better mechanistic insights into disease mechanisms and eventually allow personalised medicine.

Gut Microbiome in Children from Indigenous and Urban Communities in México: Different Subsistence Models, Different Microbiomes

The human gut microbiome is an important component that defines host health. Childhood is a particularly important period for the establishment and development of gut microbiota (GM). We sequenced the 16S rRNA gene from fecal samples of children between 5 and 10 years old, in two Mexican communities with contrasting lifestyles, i.e., “Westernized” (México City, n = 13) and “non-Westernized” (Me’phaa indigenous group, n = 29), in order to characterize and compare their GM. The main differences between these two communities were in bacteria associated with different types of diets (high animal protein and refined sugars vs. high fiber food, respectively). In addition, the GM of Me’phaa children showed higher total diversity and the presence of exclusive phyla, such as Deinococcus-Thermus, Chloroflexi, Elusimicrobia, Acidobacteria, and Fibrobacteres. In contrast, the children from México City showed less diversity and the presence of Saccharibacteria phylum, which was associated with the degradation of sugar compounds and was not present in the samples from Me’phaa children. This comparison provided further knowledge of the selective pressures affecting microbial ecosystemic composition over the course of human evolution and the potential consequences of pathophysiological states correlated with Westernization lifestyles.

Whole Blueberry and Isolated Polyphenol-Rich Fractions Modulate Specific Gut Microbes in an In Vitro Colon Model and in a Pilot Study in Human Consumers

Blueberry (BB) consumption is linked to improved health. The bioconversion of the polyphenolic content of BB by fermentative bacteria in the large intestine may be a necessary step for the health benefits attributed to BB consumption. The identification of specific gut microbiota taxa that respond to BB consumption and that mediate the bioconversion of consumed polyphenolic compounds into bioactive forms is required to improve our understanding of how polyphenols impact human health. We tested the ability of polyphenol-rich fractions purified from whole BB-namely, anthocyanins/flavonol glycosides (ANTH/FLAV), proanthocyanidins (PACs), the sugar/acid fraction (S/A), and total polyphenols (TPP)-to modulate the fecal microbiota composition of healthy adults in an in vitro colon system. In a parallel pilot study, we tested the effect of consuming 38 g of freeze-dried BB powder per day for 6 weeks on the fecal microbiota of 17 women in two age groups (i.e., young and older). The BB ingredients had a distinct effect on the fecal microbiota composition in the artificial colon model. The ANTH/FLAV and PAC fractions were more effective in promoting microbiome alpha diversity compared to S/A and TPP, and these effects were attributed to differentially responsive taxa. Dietary enrichment with BB resulted in a moderate increase in the diversity of the microbiota of the older subjects but not in younger subjects, and certain health-relevant taxa were significantly associated with BB consumption. Alterations in the abundance of some gut bacteria correlated not only with BB consumption but also with increased antioxidant activity in blood. Collectively, these pilot data support the notion that BB consumption is associated with gut microbiota changes and health benefits.

Metagenomics Study Reveals Changes in Gut Microbiota in Centenarians: A Cohort Study of Hainan Centenarians

Several studies based on 16SrDNA analysis have revealed certain unique characteristics of gut microbiome in centenarians. We established a prospective cohort of fecal microbiota and conducted the first metagenomics-based study among centenarians. The objective was to explore the dynamic changes of gut microbiota in healthy centenarians and centenarians approaching end of life and to unravel the characteristics of aging-associated microbiome. Seventy-five healthy centenarians residing in three regions of Hainan participated in follow-up surveys and collection of fecal samples at intervals of 3 months. Data pertaining to dietary status, health status scores, cause of disease and death, and fecal specimens were collected for 15 months. Twenty participants died within 20 months during the follow-up period. The median survival time was 8-9 months (range, 1-17) and the mortality rate was 14.7% per year. The health status scores before death were significantly lower than those at 3 months before the end of the follow-up period [median score: 3 (range, 1-5), P < 0.05]. At this time, the participants mainly exhibited symptoms of anorexia and reduced dietary intake and physical activity. Metagenomics sequencing and analysis were carried out to characterize the gut microbiota changes in the centenarians during their transition from healthy status to death. Anosim analysis showed a significant change in gut microbiota from 7 months prior to death (R = 0.10, P = 0.02). All participants were grouped with 7 months before death as cut-off; no significant difference in α diversity was found between the two groups (P = 0.45). Semi-supervised monitoring and log rank sum analysis revealed significant changes in the abundance of ten bacterial species before death; of these, eight species were significantly reduced (Akkermansia muciniphila, Alistipes finegoldii, Alistipes shahii, Bacteroides faecis, Bacteroides intestinalis, Butyrivibrio crossotus, Bacteroides stercoris, and Prevotella stercorea) while two were significantly increased before death (Bifidobacterium longum and Ruminococcus bromii). Compared to centenarians in northern Italy, Hainan centenarians exhibited unique characteristics of gut microbiome. The abundance of ten bacterial species showed significant changes starting from 7 months before death. We speculate that these changes might occur before the clinical symptoms of deterioration in health status.

Gut Bacteria Selectively Altered by Sennoside A Alleviate Type 2 Diabetes and Obesity Traits

Accumulating evidences implicate that gut microbiota play an important role in the onset and prolongation of fat inflammation and diabetes. Sennoside A, the main active ingredient of Rhizoma Rhei (rhubarb), is widely used for constipation as a kind of anthranoid laxative (e.g., senna). Here, we put forward the hypothesis that the structural alteration of gut microbiota in obesity mice may be involved in the pathogenesis of type 2 diabetes (T2D) which may be ameliorated by Sennoside A. We investigated the appearance of obesity, insulin resistance, host inflammation, and leaky gut phenotype with or without Sennoside A in db/db mice. Horizontal fecal microbiota transplantation (FMT) was used to confirm the critical roles of gut microbiota in the amelioration of the indices in T2D mice after Sennoside A treatment. As a result, we found that Sennoside A administration markedly improved the indices in T2D mice and obesity-related traits including blood glucose level, body weight, lipid metabolism disorder, and insulin resistance. The gut microbiota changed quickly during the onset of T2D in db/db mice, which confirmed the hypothesis that gut microbiota was involved in the pathogenesis of T2D. Sennoside A altered gut microbial composition which might mediate the antiobesogenic effects in T2D remission. Sennoside A also reduced inflammation and increased tight junction proteins in the ileum in gene-deficient mice via gut microbiota alteration. FMT lowered the blood glucose level and improved insulin resistance, corroborating that Sennoside A perhaps exerted its antiobesogenic effects through gut microbiota alteration. Chemical Compounds Studied in This Article. Compounds studied in this article include Sennoside A (PubChem CID: 73111) and metformin hydrochloride (PubChem CID: 14219).

Diverse effects of different Akkermansia muciniphila genotypes on Brown adipose tissue inflammation and whitening in a high-fat-diet murine model

BACKGROUND

The purpose of this study was to investigate the differences in the metabolic protective effects of Akkermansia muciniphila (A.muciniphila) genotypes on high-fat diet mice and explore possible mechanisms.

METHODS

Male C57BL/6 mice were randomly divided into 6 groups, including high-fat diet (HFD)+ A. muciniphila I/II/PBS group, normal control diet (NCD)+ A. muciniphila I/II/PBS group, respectively. Dietary intervention and A. muciniphila gavage were performed simultaneously. Blood glucose and lipid metabolism, brown adipose morphology and activities, and intestinal barrier function were examined after the mice were sacrificed.

RESULTS

A.muciniphila gavage improved the impaired glucose tolerance, hyperlipidemia and liver steatosis in HFD mice, and that A. muciniphila II (Amuc_GP25) was not as effective as A. muciniphila I (Amuc_GP01). This phenomenon might be because Amuc_GP01 intervention significantly inhibited brown adipose tissue whitening and inflammation induced by HFD, by repairing the intestinal barrier and relieving endotoxemia. Amuc_GP25 did not display the same results as Amuc_GP01 in HFD mice but had stronger effects in the NCD mice.

CONCLUSIONS

This study reveals the distinct functions of different A. muciniphila genotypes on diet-induced obesity, suggesting that different A. muciniphila genotypes may affect pathological conditions differently through distinct action pathways.

Viral metagenomic analysis of fecal samples reveals an enteric virome signature in irritable bowel syndrome

BACKGROUND

Changes in the enteric microbiota have been suggested to contribute to gastrointestinal diseases, including irritable bowel syndrome. Most of the published work is on bacterial dysbiosis with meager data on the role of the virome in irritable bowel syndrome and other gastrointestinal diseases. In the current study, we therefore aimed to investigate the viral community composition of the gut and test for potential dysbiosis linked to irritable bowel syndrome.

RESULTS

A metagenomics analysis on fecal samples of 50 individuals - 30 of whom met the Rome IV criteria for IBS and 20 healthy controls- was conducted. There was a noticeable alteration in viral taxa observed in association with irritable bowel syndrome when compared to healthy individuals - where some eukaryotic viral taxa noticeably prevail over others. We observed a significant decrease in the diversity and abundance of enteric virome particularly in eukaryotic viruses of Megavirales in patients with irritable bowel syndrome.

CONCLUSIONS

These findings shed light on a new hypothesis that the alteration of the viral taxa contributes to the pathogenesis of irritable bowel syndrome and related symptoms, and therefore, pave the way for developing a new diagnostic biomarker or anti-viral drugs for the treatment of irritable bowel syndrome.

Connecting the Dots Between Inflammatory Bowel Disease and Metabolic Syndrome: A Focus on Gut-Derived Metabolites

The role of the microbiome in health and disease has gained considerable attention and shed light on the etiology of complex diseases like inflammatory bowel disease (IBD) and metabolic syndrome (MetS). Since the microorganisms inhabiting the gut can confer either protective or harmful signals, understanding the functional network between the gut microbes and the host provides a comprehensive picture of health and disease status. In IBD, disruption of the gut barrier enhances microbe infiltration into the submucosae, which enhances the probability that gut-derived metabolites are translocated from the gut to the liver and pancreas. Considering inflammation and the gut microbiome can trigger intestinal barrier dysfunction, risk factors of metabolic diseases such as insulin resistance may have common roots with IBD. In this review, we focus on the overlap between IBD and MetS, and we explore the role of common metabolites in each disease in an attempt to connect a common origin, the gut microbiome and derived metabolites that affect the gut, liver and pancreas.

Targeted inhibition of gut bacterial β-glucuronidase activity enhances anticancer drug efficacy

Irinotecan treats a range of solid tumors, but its effectiveness is severely limited by gastrointestinal (GI) tract toxicity caused by gut bacterial β-glucuronidase (GUS) enzymes. Targeted bacterial GUS inhibitors have been shown to partially alleviate irinotecan-induced GI tract damage and resultant diarrhea in mice. Here, we unravel the mechanistic basis for GI protection by gut microbial GUS inhibitors using in vivo models. We use in vitro, in fimo, and in vivo models to determine whether GUS inhibition alters the anticancer efficacy of irinotecan. We demonstrate that a single dose of irinotecan increases GI bacterial GUS activity in 1 d and reduces intestinal epithelial cell proliferation in 5 d, both blocked by a single dose of a GUS inhibitor. In a tumor xenograft model, GUS inhibition prevents intestinal toxicity and maintains the antitumor efficacy of irinotecan. Remarkably, GUS inhibitor also effectively blocks the striking irinotecan-induced bloom of Enterobacteriaceae in immune-deficient mice. In a genetically engineered mouse model of cancer, GUS inhibition alleviates gut damage, improves survival, and does not alter gut microbial composition; however, by allowing dose intensification, it dramatically improves irinotecan's effectiveness, reducing tumors to a fraction of that achieved by irinotecan alone, while simultaneously promoting epithelial regeneration. These results indicate that targeted gut microbial enzyme inhibitors can improve cancer chemotherapeutic outcomes by protecting the gut epithelium from microbial dysbiosis and proliferative crypt damage.

Sexual Dimorphism of Gut Microbiota Dictates Therapeutics Efficacy of Radiation Injuries

Accidental or iatrogenic ionizing radiation exposure precipitates acute and chronic radiation injuries. The traditional paradigm of mitigating radiotherapy-associated adverse side effects has ignored the gender-specific dimorphism of patients' divergent responses. Here, the effects of sexual dimorphism on curative efficiencies of therapeutic agents is examined in murine models of irradiation injury. Oral gavage of simvastatin ameliorates radiation-induced hematopoietic injury and gastrointestinal tract dysfunction in male mice, but adversely deteriorates these radiation syndromes in female animals. In a sharp contrast, feeding animals with high-fat diet (HFD) elicites explicitly contrary results. High-throughput sequencing of microbial 16S rRNA, host miRNA, and mRNA shows that simvastatin or HFD administration preventes radiation-altered enteric bacterial taxonomic structure, preserves miRNA expression profile, and reprogrammes the spectrum of mRNA expression in small intestines of male or female mice, respectively. Notably, faecal microbiota transplantation of gut microbes from opposite sexual donors abrogates the curative effects of simvastatin or HFD in respective genders of animals. Together, these findings demonstrate that curative efficiencies of therapeutic strategies mitigating radiation toxicity might be dependent on the gender of patients, thus simvastatin or HFD might be specifically useful for fighting against radiation toxicity in a sex-dependent fashion partly based on sex-distinct gut microbiota composition in preclinical settings.

MetaMed: Linking Microbiota Functions with Medicine Therapeutics

Understanding how the human microbiome affects human health has consequences for treating disease and minimizing unwanted side effects in clinical research.

Understanding how the human microbiome affects human health has consequences for treating disease and minimizing unwanted side effects in clinical research. Here, we present MetaMed (http://metamed.rwebox.com/index), a novel and integrative system-wide correlation mapping system to link bacterial functions and medicine therapeutics, providing novel hypotheses for deep investigation of microbe therapeutic effects on human health. Furthermore, comprehensive relationships between microbes living in the environment and drugs were discovered, providing a rich source for discovering microbiota metabolites with great potential for pharmaceutical applications.

The Gut Microbiota-Brain Axis Expands Neurologic Function: A Nervous Rapport

Does exploration of the gut microbiota-brain axis expand our understanding of what it means to be human? Recognition and conceptualization of a gut microbiota-brain axis challenges our study of the nervous system. Here, integrating gut microbiota-brain research into the metaorganism model is proposed. The metaorganism-an expanded, dynamic unit comprising the host and commensal organisms-asserts a radical blurring between man and microbe. The metaorganism nervous system interacts with the exterior world through microbial-colored lenses. Ongoing studies have reported that gut microbes contribute to brain function and pathologies, even shaping higher neurological functions. How will continued collaborative efforts (e.g., between neurobiology and microbiology), including partnerships with the arts (e.g., philosophy), contribute to the knowledge of microbe-to-mind interactions? While this is not a systemic review, this nascent field is briefly described, highlighting ongoing challenges and recommendations for emerging gut microbiota-brain research. Also see the video abstract here https://youtu.be/lP9gOW8StXg.

A complex human gut microbiome cultured in an anaerobic intestine-on-a-chip

The diverse bacterial populations that comprise the commensal microbiome of the human intestine play a central role in health and disease. A method that sustains complex microbial communities in direct contact with living human intestinal cells and their overlying mucus layer in vitro would thus enable investigations of host–microbiome interactions. Here, we show the extended co-culture of living human intestinal epithelium with stable communities of aerobic and anaerobic human gut microbiota, enabled by a microfluidic intestine-on-a-chip that permits the control and real-time assessment of physiologically relevant oxygen gradients. When compared to aerobic co-culture conditions, the establishment of a transluminal hypoxia gradient in the chip increased intestinal barrier function and sustained a physiologically relevant level of microbial diversity, consisting of over 200 unique operational taxonomic units from 11 different genera, and of an abundance of obligate anaerobic bacteria with ratios of Firmicutes and Bacteroidetes similar to those observed in human faeces. The intestine-on-a-chip may serve as a discovery tool for the development of microbiome-related therapeutics, probiotics and nutraceuticals.

Microbe-metabolite-host axis, two-way action in the pathogenesis and treatment of human autoimmunity

The role of microorganism in human diseases cannot be ignored. These microorganisms have evolved together with humans and worked together with body's mechanism to maintain immune and metabolic function. Emerging evidence shows that gut microbe and their metabolites open up new doors for the study of human response mechanism. The complexity and interdependence of these microbe-metabolite-host interactions are rapidly being elucidated. There are various changes of microbial levels in models or in patients of various autoimmune diseases (AIDs). In addition, the relevant metabolites involved in mechanism mainly include short-chain fatty acids (SCFAs), bile acids (BAs), and polysaccharide A (PSA). Meanwhile, the interaction between microbes and host genes is also a factor that must be considered. It has been demonstrated that human microbes are involved in the development of a variety of AIDs, including organ-specific AIDs and systemic AIDs. At the same time, microbes or related products can be used to remodel body's response to alleviate or cure diseases. This review summarizes the latest research of microbes and their related metabolites in AIDs. More importantly, it highlights novel and potential therapeutics, including fecal microbial transplantation, probiotics, prebiotics, and synbiotics. Nonetheless, exact mechanisms still remain elusive, and future research will focus on finding a specific strain that can act as a biomarker of an autoimmune disease.

A randomised trial of probiotics to reduce severity of physiological and microbial disorders induced by partial gastrectomy for patients with gastric cancer

Gastrectomy has been widely used for the treatment of gastric cancer, and the severity of physiological and microbial disorders has greatly harmed the health of patients. In the present study, a probiotic combination containing Bifidobacterium infantis, Lactobacillus acidophilus, Enterococcus faecalis and Bacillus cereus was used to reduce the physiological disorders induced by gastrectomy via monitoring the blood index and microbial diversity using high-throughput sequencing. Our results indicated that the probiotic combination had significantly reduced the inflammation indexes (leukocyte) (p<0.05), while it markedly enhanced the immunity indexes (lymphocyte) and nutrition indexes (albumin and total protein) (p<0.05). In addition, gastric cancer had a strong influence on the microbial diversity of the stomach via enhancing the number of pathogens of Streptococcus, Peptostreptococcus and Prevotella, and reducing the percentage of the probiotic Bifidobacterium. Although partial gastrectomy markedly changed intestinal microbial diversity, the taking of the probiotic combination greatly reduced the ratio of Firmicutes/Bacteroidetes compared with patients taking no probiotics at the phylum level. At the genus level, the probiotic combination significantly enhanced the numbers of the probiotic bacteria Bacteroides, Faecalibacterium and Akkermansia and lowered the richness of Streptococcus. Therefore, we concluded that the taking of the probiotic combination significantly enhances the immune response of patients and reduces the severity of inflammation through modification of gut microbiota.

Bottoms up: the role of gut microbiota in brain health

The gut microbiota affects many aspects of human health, and research, especially over the past decade, is demonstrating that the brain is no exception. This review summarizes existing human observational studies of the microbiota in brain health and neurological conditions at all ages, as well as animal studies that are advancing the field beyond correlation and into causality. Potential mechanisms by which the brain and the gut microbiota are connected are explored, including inflammation, bacterially-produced metabolites and neurotransmitters and specific roles for individual microbes. Finally, important challenges and potential mitigation strategies are discussed, as well as ways in which some of these same challenges can be harnessed to advance our understanding of this complex, exciting and rapidly evolving field.

Glycation of fish protein impacts its fermentation metabolites and gut microbiota during in vitro human colonic fermentation

The aim of this study was to investigate the fermentation properties of fish protein (FP) glycated with glucose at two different heating time (24 h and 48 h, 50 °C, GFP24 and GFP48), using an in vitro batch fermentation model of human distal colon. The heated fish protein in absent of glucose was also as controls. The lower glycation extent of fish protein, with a lower browning intensity and bound sugar, enhanced the production of acetate and propionate. The formation of indole and ammonia was inhibited by the glycation of fish protein, but less affected by its glycation extent. Compared to FP, the glycation of fish protein significantly increased (p < .05) the relative abundance of genera Lactococcus for GFP24 (47%) and GFP48 (71%), whereas decreased dominant genera Bacteroides for GFP24 (32%) and GFP48 (23%). Compared to GFP24, GFP48 indicated significantly higher relative abundance of Holdemania, Streptococcus, Enterococcus and Lactobacillus, and lower amounts of Parabacteroides (p < .05). In the meantime, the heated treatments in the absent of glucose resulted in the increase of some genera Dialister, Arobacter, Clostridium_sensu_stricto_1, Phascolarctobacterium and Veillonella, and also ammonia production. Furthermore, the correlation analysis confirmed that the glycation of fish protein for the decrease of ammonia and indole production was associated with the changes of some proteolytic bacteria genera, including Bacteroides, Dialister and Parabacteroides. Thus, the glycated fish protein rich in Amadori products greatly change the profiles of fermentation metabolite and gut microbiota, and these changes can have a potential impact on host health.