Biodiversity of Gut Microbiota: Impact of Various Host and Environmental Factors

Gut microbiota and Alzheimer's disease: Exploring natural product intervention and the Gut-Brain axis for therapeutic strategies

Numerous studies conducted over the last ten years have shown a strong correlation between the gut microbiota and the onset and progression of Alzheimer's disease (AD). However, the exact underlying mechanism is still unknown. An ongoing communication mechanism linking the gut and the brain is highlighted by the term "microbiota-gut-brain axis," which was originally coined the "gut-brain axis." Key metabolic, endocrine, neurological, and immunological mechanisms are involved in the microbiota‒gut‒brain axis and are essential for preserving brain homeostasis. Thus, the main emphasis of this review is how the gut microbiota contributes to the development of AD and how various natural products intervene in this disease. The first part of the review provides an outline of various pathways and relationships between the brain and gut microbiota, and the second part provides various mechanisms involved in the gut microbiota and AD. Finally, this review provides knowledge about natural products and their effectiveness in treating gut microbiota-induced AD. AD may be treated in the future by altering the gut microbiota with a customized diet, probiotics/prebiotics, plant products, and natural products. This entails altering the microbiological partners and products (such as amyloid protein) that these partners generate.

The importance of gut microbiome in the perinatal period

This narrative review describes the settlement of the neonatal microbiome during the perinatal period and its importance on human health in the long term. Delivery methods, maternal diet, antibiotic exposure, feeding practices, and early infant contact significantly shape microbial colonization, influencing the infant's immune system, metabolism, and neurodevelopment. By summarizing two decades of research, this review highlights the microbiome's role in disease predisposition and explores interventions like maternal vaginal seeding and probiotic and prebiotic supplementation that may influence microbiome development.

CONCLUSION

The perinatal period is a pivotal phase for the formation and growth of the neonatal microbiome, profoundly impacting long-term health outcomes.

WHAT IS KNOWN

• The perinatal period is a critical phase for the development of the neonatal microbiome, with factors such as mode of delivery, maternal diet, antibiotic exposure, and feeding practices influencing its composition and diversity, which has significant implications for long-term health. • The neonatal microbiome plays a vital role in shaping the immune system, metabolism, and neurodevelopment of infants.

WHAT IS NEW

• Recent studies have highlighted the potential of targeted interventions, such as probiotic and prebiotic supplementation, and innovative practices like maternal vaginal seeding, to optimize microbiome development during the perinatal period. • Emerging evidence suggests that specific bacterial genera and species within the neonatal microbiome are associated with reduced risks of developing chronic conditions, indicating new avenues for promoting long-term health starting from early life.

Gut microbiota modulating therapy for diabetes mellitus should be individualized

In this editorial, we commented on two articles published online in August and September 2024 in the World Journal of Diabetes, which focused on modifying the gut microbiota (GM) to prevent or delay the progression of diabetes mellitus (DM) and DM-related complications. Numerous studies, many of which are animal studies, have indicated the potential role of GM in the pathogenesis of DM. However, the detailed causality and mechanisms between GM and DM have not been fully clarified. Although there have been some reports of a potential role of modifying the GM in treating DM, most lack long-term observations and are not mechanistic. Additionally, the GM and its role in DM might vary among individuals; therefore, GM-targeted interventions should be individualized to realize their therapeutic potential.

Effects of Tanreqing injection on the gut microbiota in healthy volunteers

Objectives

Many studies have confirmed that antibacterial agents can disrupt the human gut microbiota. In China, Tanreqing injection (TRQ) is a drug with antibacterial activity that is widely used in the treatment of respiratory infections. However, its specific influence on gut microbiota remains unclear. This study aimed to investigate the effect of TRQ on the gut microbiota of healthy volunteers.

Methods

Twelve healthy adults received 20 ml of TRQ intravenously daily for 7 consecutive days. At six timepoints (Pre, on D1, D3, D5, D7 and follow-up visit) fecal samples were collected and analyzed using 16S rRNA gene sequencing.

Results

Eleven people were included in the analysis finally. TRQ did not significantly alter gut microbiota diversity or richness (Shannon and Simpson and Chao1 index) in healthy people during the intervention. Gut microbial structure was stable (weighted and unweighted Unifrac). Using a machine learning method based on PLS-DA analysis, the separation trend on D7 at the genus level was found, returning to baseline two days after discontinuation. The abundance of major genus fluctuated on D7 compared with that prior to treatment, including an increase of unclassified_f_Enterobacteriaceae (13.0611%), a decrease of Bifidobacterium and Escherichia-Shigella (6.887%, 10.487%). Functional prediction analysis did not reveal any significant difference.

Conclusions

Our study showed short-term use of TRQ at conventional doses may not cause perturbations to the gut microbiota in healthy adults. This finding provides some useful information for the safe use of TRQ in the treatment of respiratory infections.

Clinical trial registration

https://www.medicalresearch.org.cn/, identifier MR-31-24-014367.

[The human microbiome proofed by the Anthropocene: from correlation to causality and intervention]

The deleterious effects of human activities on biodiversity in the vegetal and animal world, and on climate changes are now well-established facts. However, little is yet known on the impact of human activities on microbial diversity on the planet and more specifically on the human microbiota Large implementation of metagenomics allows exaustive microbial cataloguing with broad spatio-temporal resolution of human microbiota. A reduction in bacterial richness and diversity in the human microbiota, particularly in the intestinal tract, is now established and particularly obvious in the most industrialized regions of the planet. Massive, uncontrolled use of antibiotics, drastic changes in traditional food habits and some elements of the "global exposome" that remain to identify are usually considered as stressors accounting for this situation of "missing microbes". As a consequence, a dysbiotic situation develops, a "dysbiosis" being characterized by the erosion of the central core of shared bacterial species across individuals and the development of opportunistic "pathobionts" in response to a weaker barrier capacity of these impoverished microbiota. The current challenge is to establish a causality link between the extension of these dysbiotic situations and the steady emergence of epidemic, non-communicable diseases such as asthma, allergy, obesity, diabetes, autoimmune diseases and some cancers. Experimental animal models combined with controlled, prospective clinical interventions are in demand to consolidate causality links, with the understanding that in the deciphering of the mechanisms of alteration of the human-microbiome symbiosis resides a novel exciting chapter of medicine: "microbial medicine".

Geographic and environmental impacts on gut microbiome in Himalayan langurs (Semnopithecus schistaceus) and Xizang macaques (Macaca mulatta vestita)

Introduction

Gut microbiome plays a crucial role in the health of wild animals. Their structural and functional properties not only reflect the host's dietary habits and habitat conditions but also provide essential support for ecological adaptation in various environments.

Methods

This study investigated the gut microbiome of Himalayan langurs (Semnopithecus schistaceus) and Xizang macaques (Macaca mulatta vestita) across different geographic regions using 16S rRNA gene and metagenomic sequencing.

Results

Results showed distinct clustering patterns in gut microbiota based on geographic location. Soil had an insignificant impact on host gut microbiome. Himalayan langurs from mid-altitude regions exhibited higher levels of antibiotic resistance genes associated with multidrug resistance, while Xizang macaques from high-altitude regions showed a broader range of resistance genes. Variations in carbohydrate-active enzymes and KEGG pathways indicated unique metabolic adaptations to different environments.

Discussion

These findings provide valuable insights into the health and conservation of these primates and the broader implications of microbial ecology and functional adaptations in extreme conditions.

The interplay between gut microbiome and physical exercise in athletes

PURPOSE OF REVIEW

The gut microbiome regulates several health and disease-related processes. However, the potential bidirectional relationship between the gut microbiome and physical exercise remains uncertain. Here, we review the evidence related to the gut microbiome in athletes.

RECENT FINDINGS

The effect of physical exercise on the intestinal microbiome and intestinal epithelial cells depends on the type, volume, and intensity of the activity. Strenuous exercise negatively impacts the intestinal microbiome, but adequate training and dietary planning could mitigate these effects. An increase in short-chain fatty acids (SCFAs) concentrations can modulate signaling pathways in skeletal muscle, contributing to greater metabolic efficiency, preserving muscle glycogen, and consequently optimizing physical performance and recovery. Furthermore, higher SCFAs concentrations appear to lower inflammatory response, consequently preventing an exacerbated immune response and reducing the risk of infections among athletes. Regarding dietary interventions, the optimal diet composition for targeting the athlete's microbiome is not yet known. Likewise, the benefits or harms of using probiotics, synbiotics, and postbiotics are not well established, whereas prebiotics appear to optimize SCFAs production.

SUMMARY

The intestinal microbiome plays an important role in modulating health, performance, and recovery in athletes. SCFAs appear to be the main intestinal metabolite related to these effects. Nutritional strategies focusing on the intestinal microbiome need to be developed and tested in well controlled clinical trials.

Microbiota alterations associated with vascular diseases: postbiotics as a next-generation magic bullet for gut-vascular axis

The intestinal microbiota represents a key element in maintaining the homeostasis and health conditions of the host. Vascular pathologies and other risk factors such as aging have been recently associated with dysbiosis. The qualitative and quantitative alteration of the intestinal microbiota hinders correct metabolic homeostasis, causing structural and functional changes of the intestinal wall itself. Impairment of the intestinal microbiota, combined with the reduction of the barrier function, worsen the pathological scenarios of peripheral tissues over time, including the vascular one. Several experimental evidence, collected in this review, describes in detail the changes of the intestinal microbiota in dysbiosis associated with vascular alterations, such as atherosclerosis, hypertension, and endothelial dysfunction, the resulting metabolic disorders and how these can impact on vascular health. In this context, the gut-vascular axis is considered, for the first time, as a merged unit involved in the development and progression of vascular pathologies and as a promising target. Current approaches for the management of dysbiosis such as probiotics, prebiotics and dietary modifications act mainly on the intestinal district. Postbiotics, described as preparation of inanimate microorganisms and/or their components that confers health benefits on the host, represent an innovative strategy for a dual management of intestinal dysbiosis and vascular pathologies. In this context, this review has the further purpose of defining the positive effects of the supplementation of bacterial strains metabolites (short‑chain fatty acids, exopolysaccharides, lipoteichoic acids, gallic acid, and protocatechuic acid) restoring intestinal homeostasis and acting directly on the vascular district through the gut-vascular axis.

Alteration of ascending colon mucosal microbiota in patients after cholecystectomy

BACKGROUND

Cholecystectomy is a successful treatment option for gallstones, although the incidence of colorectal cancer (CRC) has notably increased in post-cholecystectomy (PC) patients. However, it remains uncertain whether the altered mucosal microbiota in the ascending colon is related.

AIM

To investigate the potential correlation between gut microbiota and the surgical procedure of cholecystectomy.

METHODS

In total, 30 PC patients and 28 healthy controls underwent colonoscopies to collect mucosal biopsy samples. PC patients were divided based on their clinical features. Then, 16S-rRNA gene sequencing was used to analyze the amplicon, alpha diversity, beta diversity, and composition of the bacterial communities. Additionally, the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) database, sourced from the Kyoto Encyclopedia of Genes and Genomes, was used to predict the functional capabilities of the bacteria.

RESULTS

PC patients were comparable with healthy controls. However, PC patients older than 60 years had a distinct composition compared to those under 60 years old. Bacteroidetes richness was considerably higher at the phylum level in PC patients. Bacteroides, Parabacteroides, and Bilophila were more abundant in the PC group than in the control group. Furthermore, PC patients exhibited greater enrichment in metabolic pathways, specifically those related to lipopolysaccharide biosynthesis and vancomycin group antibiotic production, than controls.

CONCLUSION

This study indicated that the mucosal microbiota in PC patients was altered, perhaps offering new perspectives on the treatment possibilities for CRC and diarrhea following cholecystectomy.

Unveiling the influence of a probiotic combination of Heyndrickxia coagulans and Lacticaseibacillus casei on healthy human gut microbiota using the TripleSHIME® system

Probiotics are host-friendly microorganisms that can have important health benefits in the human gut microbiota as dietary supplements. Maintaining a healthy gut microbial balance relies on the intricate interplay among the intestinal microbiota, metabolic activities, and the host's immune response. This study aims to explore if a mixture of Heyndrickxia coagulans [ATB-BCS-042] and Lacticaseibacillus casei [THT-030-401] promotes in vitro this balance in representative gut microbiota from healthy individuals using the Triple-SHIME® (Simulation of the Human Intestinal Microbial Ecosystem). Metataxonomic analysis of the intestinal microbes revealed that the probiotic mix was not causing important disruptions in the biodiversity or microbial composition of the three simulated microbiota. However, some targeted populations analyzed by qPCR were found to be disrupted at the end of the probiotic treatment or after one week of washout. Populations such as Cluster IV, Cluster XVIa, and Roseburia spp., were increased indicating a potential gut health-promoting butyrogenic effect of the probiotic supplementation. In two of the systems, bifidogenic effects were observed, while in the third, the treatment caused a decrease in bifidobacteria. For the health-detrimental biomarker Escherichia-Shigella, a mild decrease in all systems was observed in the proximal colon sections, but these genera were highly increased in the distal colon sections. By the end of the washout, Bacteroides-Prevotella was found consistently boosted, which could have inflammatory consequences in the intestinal context. Although the probiotics had minimal influence on most quantified metabolites, ammonia consistently decreased after one week of daily probiotic supplementation. In reporter gene assays, aryl hydrocarbon receptor (AhR) activation was favored by the metabolic output obtained from post-treatment periods. Exposure of a human intestinal cell model to fermentation supernatant obtained after probiotic supplementation induced a trend to decrease the mRNA expression of immunomodulatory cytokines (IL-6, IL-8). Overall, with some exceptions, a positive impact of H. coagulans and L. casei probiotic mix was observed in the three parallel experiments, despite inter-individual differences. This study might serve as an in vitro pipeline for the impact assessment of probiotic combinations on the human gut microbiota.

Interactions between Dietary Antioxidants, Dietary Fiber and the Gut Microbiome: Their Putative Role in Inflammation and Cancer

The intricate relationship between the gastrointestinal (GI) microbiome and the progression of chronic non-communicable diseases underscores the significance of developing strategies to modulate the GI microbiota for promoting human health. The administration of probiotics and prebiotics represents a good strategy that enhances the population of beneficial bacteria in the intestinal lumen post-consumption, which has a positive impact on human health. In addition, dietary fibers serve as a significant energy source for bacteria inhabiting the cecum and colon. Research articles and reviews sourced from various global databases were systematically analyzed using specific phrases and keywords to investigate these relationships. There is a clear association between dietary fiber intake and improved colon function, gut motility, and reduced colorectal cancer (CRC) risk. Moreover, the state of health is reflected in the reciprocal and bidirectional relationships among food, dietary antioxidants, inflammation, and body composition. They are known for their antioxidant properties and their ability to inhibit angiogenesis, metastasis, and cell proliferation. Additionally, they promote cell survival, modulate immune and inflammatory responses, and inactivate pro-carcinogens. These actions collectively contribute to their role in cancer prevention. In different investigations, antioxidant supplements containing vitamins have been shown to lower the risk of specific cancer types. In contrast, some evidence suggests that taking antioxidant supplements can increase the risk of developing cancer. Ultimately, collaborative efforts among immunologists, clinicians, nutritionists, and dietitians are imperative for designing well-structured nutritional trials to corroborate the clinical efficacy of dietary therapy in managing inflammation and preventing carcinogenesis. This review seeks to explore the interrelationships among dietary antioxidants, dietary fiber, and the gut microbiome, with a particular focus on their potential implications in inflammation and cancer.

The hidden threat: Environmental toxins and their effects on gut microbiota

The human gut microbiota (GM), which consists of a complex and diverse ecosystem of bacteria, plays a vital role in overall wellness. However, the delicate balance of this intricate system is being compromised by the widespread presence of environmental toxins. The intricate connection between contaminants in the environment and human well-being has garnered significant attention in recent times. Although many environmental pollutants and their toxicity have been identified and studied in laboratory settings and animal models, there is insufficient data concerning their relevance to human physiology. Consequently, research on the toxicity of environmental toxins in GM has gained prominence in recent years. Various factors, such as air pollution, chemicals, heavy metals, and pesticides, have a detrimental impact on the composition and functioning of the GM. This comprehensive review aims to comprehend the toxic effects of numerous environmental pollutants, including antibiotics, endocrine-disrupting chemicals, heavy metals, and pesticides, on GM by examining recent research findings. The current analysis concludes that different types of environmental toxins can lead to GM dysbiosis and have various potential adverse effects on the well-being of animals. We investigate the alterations to the GM composition induced by contaminants and their impact on overall well-being, providing a fresh perspective on research related to pollutant exposure.

Polysaccharides from exudate gums of plants and interactions with the intestinal microbiota: A review of vegetal biopolymers and prediction of their prebiotic potential

Polysaccharides in plant-exuded gums are complex biopolymers consisting of a wide range of structural variability (linkages, monosaccharide composition, substituents, conformation, chain length and branching). The structural features of polysaccharides confer the ability to be exploited in different industrial sectors and applications involving biological systems. Moreover, these characteristics are attributed to a direct relationship in the process of polysaccharide enzymatic degradation by the fermentative action in the gut microbiota, through intrinsic interactions connecting bacterial metabolism and the production of various metabolites that are associated with regulatory effects on the host homeostasis system. Molecular docking analysis between bacterial target proteins and arabinogalactan-type polysaccharide obtained from gum arabic allowed the identification of intermolecular interactions provided bacterial enzymatic mechanism for the degradation of several arabinogalactan monosaccharide chains, as a model for the study and prediction of potential fermentable polysaccharide. This review discusses the main structural characteristics of polysaccharides from exudate gums of plants and their interactions with the intestinal microbiota.

Intestinal microbiome dysbiosis in alcohol-dependent patients and its effect on rat behaviors

IMPORTANCE

Intestinal microbiome dysbiosis is associated with psychiatric disease through the "microbiota-gut-brain" axis. Here, we revealed that there was obvious intestinal microbiome (including bacterial and fungal) dysbiosis in alcohol-dependent patients. Alcohol consumption seriously disturbs the gut equilibrium between bacteria and fungi, reduces the interactions among bacterial-fungal trans-kingdom, and increases intestinal permeability. Gut microbiota should be considered as a whole to study the development of alcohol dependence. The gut microbiome of alcohol-dependent patients increased the anxiety- and depression-like behavior in rats. The gut microbiota dysbiosis may promote the development of alcohol dependence by regulating the endogenous cholecystokinin (CCK) and related receptors. Hence, regulating the balance of gut microbiota and the endogenous CCK may be a potential strategy for reducing the risk of relapse in alcohol addiction patients.

Stimulation of Pro-inflammatory Cytokines in Mixed Cultures of Peripheral Blood Mononuclear Cells and Anaerobic Bacteria

In the last couple of decades, much progress has been made in studying bacteria living in humans. However, there is much more to learn about bacteria immune cell interactions. Here, we show that anaerobic bacteria do not grow when cultured overnight with human cells under atmospheric air. Air contains about 18% oxygen, which inhibits the growth of these bacteria while supporting the cultivation of human cells. The bacteria cultured with human peripheral blood mononuclear cells (PBMCs) inflamed with phytohemagglutinin (PHA) greatly increased the production of proinflammatory cytokines like tumor necrosis factor-alpha (TNFα) while inhibiting the production of monocyte chemoattractant protein-1 (MCP-1), an important chemokine.

Targeting gut microbiota in aging-related cardiovascular dysfunction: focus on the mechanisms

The global population is aging and age-related cardiovascular disease is increasing. Even after controlling for cardiovascular risk factors, readmission and mortality rates remain high. In recent years, more and more in-depth studies have found that the composition of the gut microbiota and its metabolites, such as trimethylamine N-oxide (TMAO), bile acids (BAs), and short-chain fatty acids (SCFAs), affect the occurrence and development of age-related cardiovascular diseases through a variety of molecular pathways, providing a new target for therapy. In this review, we discuss the relationship between the gut microbiota and age-related cardiovascular diseases, and propose that the gut microbiota could be a new therapeutic target for preventing and treating cardiovascular diseases.

The gut microbiome meets nanomaterials: exposure and interplay with graphene nanoparticles

Graphene-based nanoparticles are widely applied in many technology and science sectors, raising concerns about potential health risks. Emerging evidence suggests that graphene-based nanomaterials may interact with microorganisms, both pathogens and commensal bacteria, that dwell in the gut. This review aims to demonstrate the current state of knowledge on the interplay between graphene nanomaterials and the gut microbiome. In this study, we briefly overview nanomaterials, their usage and the characteristics of graphene-based nanoparticles. We present and discuss experimental data from in vitro studies, screening tests on small animals and rodent experiments related to exposure and the effects of graphene nanoparticles on gut microbiota. With this in mind, we highlight the reported crosstalk between graphene nanostructures, the gut microbial community and the host immune system in order to shed light on the perspective to bear on the biological interactions. The studies show that graphene-based material exposure is dosage and time-dependent, and different derivatives present various effects on host bacteria cells. Moreover, the route of graphene exposure might influence a shift in the gut microbiota composition, including the alteration of functions and diversity and abundance of specific phyla or genera. However, the mechanism of graphene-based nanomaterials' influence on gut microbiota is poorly understood. Accordingly, this review emphasises the importance of studies needed to establish the most desirable synthesis methods, types of derivatives, properties, and safety aspects mainly related to the routes of exposure and dosages of graphene-based nanomaterials.

Effect of Different Feeds on the Fungi Microbiome of Suffolk Crossed with Tibetan Sheep

The gut microbiome plays an important role in the metabolism, nutrient absorption and immunocompetency of animals. The dynamics of the microbiota can be influenced by modulatory factors that involve nutrition, environment, health, diseases, etc. Few reports have been documented regarding the effects of different feeds on the fungi microbiome of Suffolk crossed with Tibetan sheep. A total of 30 Suffolk crossed with Tibetan sheep (ST sheep) were selected for the study and randomly divided into five equal groups (n = 6): AZ, BZ, CZ, DZ and EZ. Group AZ was fed with alfalfa and oat grass, whereas group BZ was fed with mixture of concentrated feed, alfalfa and oat grass. Groups CZ, DZ and EZ were fed with concentrated feed #1, #2 and #3, respectively. All experimental animals were fed twice a day for four months, and rectum samples were collected for microbiota analysis. Results revealed that 2,781,461 raw reads and 2,333,239 clean reads were achieved in the ST sheep. When compared with the sheep of groups AZ and BZ (164), the shared amplicon sequence variants (ASVs) between AZ and CZ (109), AZ (113) and DZ (118) as well as AZ along with EZ were fewer. Conspicuous different phyla (8) and genera (56) were examined and compared with free-range sheep in AZ. Genera including Xeromyces, Kazachstania, Cordyceps, Rhodotorula, Pichia, Spor, etc. were found higher in animals in the CZ, DZ and EZ groups. The results of this study provide new insights regarding the effects of different feeds on the fungi microbiome of sheep farmed on the plateau. We concluded that the differences in feed in Suffolk crossed with Tibetan sheep altered their gut microbiota.

Intestinal Flora in Chemotherapy Resistance of Biliary Pancreatic Cancer

Biliary pancreatic malignancy has an occultic onset, a high degree of malignancy, and a poor prognosis. Most clinical patients miss the opportunity for surgical resection of the tumor. Systemic chemotherapy is still one of the important methods for the treatment of biliary pancreatic malignancies. Many chemotherapy regimens are available, but their efficacy is not satisfactory, and the occurrence of chemotherapy resistance is a major reason leading to poor prognosis. With the advancement of studies on intestinal flora, it has been found that intestinal flora is correlated with and plays an important role in chemotherapy resistance. The application of probiotics and other ways to regulate intestinal flora can improve this problem. This paper aims to review and analyze the research progress of intestinal flora in the chemotherapy resistance of biliary pancreatic malignancies to provide new ideas for treatment.

Microbiota dysbiosis caused by dietetic patterns as a promoter of Alzheimer's disease through metabolic syndrome mechanisms

Microbiota dysbiosis and metabolic syndrome, consequences of a non-adequate diet, generate a feedback pathogenic state implicated in Alzheimer's disease development. The lower production of short chain fatty acids (SCFAs) under dysbiosis status leads to lipid homeostasis deregulation and decreases Angptl4 release and AMPK activation in the adipose tissue, promoting higher lipid storage (adipocyte hypertrophy) and cholesterol levels. Also, low SCFA generation reduces GPR41 and GPR43 receptor activation at the adipose tissue (increasing leptin release and leptin receptor resistance) and intestinal levels, reducing the release of GLP-1 and YPP. Therefore, lower satiety sensation and energy expenditure occur, promoting a weight gaining environment mediated by higher food intake and lipid storage, developing dyslipemia. In this context, higher glucose levels, together with higher free fatty acids in the bloodstream, promote glycolipotoxicity, provoking a reduction in insulin released, insulin receptor resistance, advanced glycation products (AGEs) and type 2 diabetes. Intestinal dysbiosis and low SCFAs reduce bacterial biodiversity, increasing lipopolysaccharide (LPS)-producing bacteria and intestinal barrier permeability. Higher amounts of LPS pass to the bloodstream (endotoxemia), causing a low-grade chronic inflammatory state characterized by higher levels of leptin, IL-1β, IL-6 and TNF-α, together with a reduced release of adiponectin and IL-10. At the brain and neuronal levels, the generated insulin resistance, low-grade chronic inflammation, leptin resistance, AGE production and LPS increase directly impact the secretase enzymes and tau hyperphosphorylation, creating an enabling environment for β-amyloid senile plaque and tau tangled formations and, as a consequence, Alzheimer's initiation, development and maintenance.

Gut microbiome and serum short-chain fatty acids are associated with responses to chemo- or targeted therapies in Chinese patients with lung cancer

Background

The association between gut microbes and short-chain fatty acids (SCFAs) and therapeutic responses of patients with lung cancer (LC) receiving therapy remains unknown.

Methods

Fecal and serum samples were prospectively collected from patients with LC, classified as responders, if they presented durable clinical benefits, and non-responders, if not. The composition of gut microbes was analyzed using 16S ribosomal DNA sequencing. Serum SCFA concentrations were detected using gas chromatography. Cell proliferation, migration, invasion, cell cycle, and apoptosis assays were performed on isobutyric acid-treated A549 cells. Reverse transcription-quantitative PCR, Western blotting, immunocytochemistry, and immunofluorescence staining experiments have been performed to investigate the expression of associated genes or proteins.

Results

Non-responders harbored higher microbiome α-diversity but lower β-diversity compared with responders. Compared to the patients with low α-diversity, those with high α-diversity showed significantly shorter progression-free survival. Additionally, β-diversity has also been observed between these two groups. Specifically, Parasutterella, Clostridiaceae, and Prevotella_7 were more abundant among responders, whereas Bacteroides_stercoris and Christensenellaceae_R-7_group were more abundant in non-responders. The serum SCFA (especially acetate and isobutyrate) levels tended to be higher in responders. Isobutyric acid inhibited the proliferation, migration, and invasion of A549 cells by inducing apoptosis and G1/S arrest while upregulating the expression of GPR41, GPR43, and GPR5C and downregulating that of PAR1, and increasing the activity of histone acetyltransferases.

Conclusion

We revealed the influence of gut microbiota and SCFAs on the therapeutic responses in patients with LC and the anti-tumor effect of isobutyric acid, indicating their potential use as therapeutic targets.

Seasonal Variation in Gut Microbiota of the Wild Daurian Ground Squirrel (Spermophilus dauricus): Metagenomic Insights into Seasonal Breeding

The Spermophilus dauricus, the wild Daurian ground squirrel, is known to exhibit seasonal breeding behavior. Although the importance of gut microbiota in animal digestion, metabolism, and immunity is well-established, the correlation between gut microbiota and seasonal breeding in this species remains inadequately explored. In the present study, using metagenomic sequencing technology, the compositions and functions of the gut microbiota of wild Daurian ground squirrels in different breeding seasons were explored. The dominant gut microbial phyla were Firmicutes and Bacteroidetes. The Firmicutes were predominant in the breeding season, whereas Bacteroidetes were predominant in the non-breeding season. At the genus level, Lactobacillus accumulated during the breeding season, whereas Odoribacter and Alistipes increased during the non-breeding season. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genome) annotations indicated that genes in gut samples were highly associated with metabolic functions. The differential expression gene analysis showed that genes related to the phosphotransferase system, cysteine, and methionine metabolism were highly expressed during the breeding season, whereas the non-breeding season upregulated genes were enriched in starch and sucrose metabolism and bacterial chemotaxis pathways. In conclusion, this study could provide a reference for investigating gut microbiota in seasonal breeding animals and offer new insight into gut microbial function.

Strategies to Assess the Impact of Sustainable Functional Food Ingredients on Gut Microbiota

Nowadays, it is evident that food ingredients have different roles and distinct health benefits to the consumer. Over the past years, the interest in functional foods, especially those targeting gut health, has grown significantly. The use of industrial byproducts as a source of new functional and sustainable ingredients as a response to such demands has raised interest. However, the properties of these ingredients can be affected once incorporated into different food matrices. Therefore, when searching for the least costly and most suitable, beneficial, and sustainable formulations, it is necessary to understand how such ingredients perform when supplemented in different food matrices and how they impact the host's health. As proposed in this manuscript, the ingredients' properties can be first evaluated using in vitro gastrointestinal tract (GIT) simulation models prior to validation through human clinical trials. In vitro models are powerful tools that mimic the physicochemical and physiological conditions of the GIT, enabling prediction of the potentials of functional ingredients per se and when incorporated into a food matrix. Understanding how newly developed ingredients from undervalued agro-industrial sources behave as supplements supports the development of new and more sustainable functional foods while scientifically backing up health-benefits claims.

Effects of Lactiplantibacillus plantarum FBT215 and prebiotics on the gut microbiota structure of mice

Imbalanced intestinal microbiota is associated with diseases, including inflammatory bowel disease and obesity, and diet can alter the structure of the gut microbiota. In this study, the effects of dietary treatments including the potential probiotic Lactiplantibacillus plantarum FBT215 with/without prebiotics on the intestinal microbiota composition of mice were investigated. Lactiplantibacillus plantarum FBT215 administration significantly decreased the Firmicutes/Bacteroidetes ratio and increased the abundance of Muribaculum and Duncaniella. The diversity within and between groups was measured according to α and β diversity metrics, respectively. The Shannon index of α diversity decreased significantly in all treatment groups except the probiotic group, although this group showed an increase in the Chao1 index. Principal coordinate analysis of β diversity showed that the groups had different species distributions. Finally, gamma-aminobutyric acid (GABA) concentration increased in groups fed L. plantarum FBT215. These findings improve our understanding of the association between the gut microbiota structure and specific probiotic/prebiotic-containing diets.

Gut microbiota therapy for nonalcoholic fatty liver disease: Evidence from randomized clinical trials

Nonalcoholic fatty liver disease (NAFLD) has a high prevalence worldwide, but there are no medications approved for treatment. Gut microbiota would be a novel and promising therapeutic target based on the concept of the gut-liver axis in liver disease. We reviewed randomized controlled trials on gut microbiota therapy in NAFLD in this study to evaluate its efficacy and plausibility in NAFLD.

Candida albicans-enteric viral interactions-The prostaglandin E2 connection and host immune responses

The human microbiome comprises trillions of microorganisms residing within different mucosal cavities and across the body surface. The gut microbiota modulates host susceptibility to viral infections in several ways, and microbial interkingdom interactions increase viral infectivity within the gut. Candida albicans, a frequently encountered fungal species in the gut, produces highly structured biofilms and eicosanoids such as prostaglandin E₂ (PGE₂), which aid in viral protection and replication. These biofilms encompass viruses and provide a shield from antiviral drugs or the immune system. PGE₂ is a key modulator of active inflammation with the potential to regulate interferon signaling upon microbial invasion or viral infections. In this review, we raise the perspective of gut interkingdom interactions involving C. albicans and enteric viruses, with a special focus on biofilms, PGE₂, and viral replication. Ultimately, we discuss the possible implications of C. albicans-enteric virus associations on host immune responses, particularly the interferon signaling pathway.

Regulatory effects of marine polysaccharides on gut microbiota dysbiosis: A review

The gut microbiota dysbiosis is a state which the physiological combinations of flora are transformed into pathological combinations caused by factors such as diets, pollution, and drugs. Increasing evidence shows that dysbiosis is closely related to many diseases. With the continuous development and utilization of marine resources, marine polysaccharides have been found to regulate dysbiosis in many studies. In this review, we introduce the types of dysbiosis and the degree of it caused by different factors. We highlight the regulating effects of marine polysaccharides on dysbiosis as a potential prebiotic. The mechanisms of marine polysaccharides to regulate dysbiosis including protection of intestinal barrier, regulatory effect on gut microbiota, alteration for related metabolites, and some other possible mechanisms were summarized. And we aim to provide some references for the high-value utilization of marine polysaccharides and new targets for the treatment of gut microbiota dysbiosis by this review.

Personalized nutrition, microbiota, and metabolism: A triad for eudaimonia

During the previous few years, the relationship between the gut microbiota, metabolic disorders, and diet has come to light, especially due to the understanding of the mechanisms that particularly link the gut microbiota with obesity in animal models and clinical trials. Research has led to the understanding that the responses of individuals to dietary inputs vary remarkably therefore no single diet can be suggested to every individual. The variations are attributed to differences in the microbiome and host characteristics. In general, it is believed that the immanent nature of host-derived factors makes them difficult to modulate. However, diet can more easily shape the microbiome, potentially influencing human physiology through modulation of digestion, absorption, mucosal immune response, and the availability of bioactive compounds. Thus, diet could be useful to influence the physiology of the host, as well as to ameliorate various disorders. In the present study, we have described recent developments in understanding the disparities of gut microbiota populations between individuals and the primary role of diet-microbiota interactions in modulating human physiology. A deeper understanding of these relationships can be useful for proposing personalized nutrition strategies and nutrition-based therapeutic interventions to improve human health.

Interactive Relationships between Intestinal Flora and Bile Acids

The digestive tract is replete with complex and diverse microbial communities that are important for the regulation of multiple pathophysiological processes in humans and animals, particularly those involved in the maintenance of intestinal homeostasis, immunity, inflammation, and tumorigenesis. The diversity of bile acids is a result of the joint efforts of host and intestinal microflora. There is a bidirectional relationship between the microbial community of the intestinal tract and bile acids in that, while the microbial flora tightly modulates the metabolism and synthesis of bile acids, the bile acid pool and composition affect the diversity and the homeostasis of the intestinal flora. Homeostatic imbalances of bile acid and intestinal flora systems may lead to the development of a variety of diseases, such as inflammatory bowel disease (IBD), colorectal cancer (CRC), hepatocellular carcinoma (HCC), type 2 diabetes (T2DM), and polycystic ovary syndrome (PCOS). The interactions between bile acids and intestinal flora may be (in)directly involved in the pathogenesis of these diseases.

Nasal Microbiota, Olfactory Health, Neurological Disorders and Aging—A Review

The nasal region is one of the distinct environments for the survival of various microbiota. The human microbial niche begins to inhabit the human body right from birth, and the microbiota survive as commensals or opportunistic pathogens throughout the life of humans in their bodies in various habitats. These microbial communities help to maintain a healthy microenvironment by preventing the attack of pathogens and being involved in immune regulation. Any dysbiosis of microbiota residing in the mucosal surfaces, such as the nasal passages, guts, and genital regions, causes immune modulation and severe infections. The coexistence of microorganisms in the mucosal layers of respiratory passage, resulting in infections due to their co-abundance and interactions, and the background molecular mechanisms responsible for such interactions, need to be considered for investigation. Additional clinical evaluations can explain the interactions among the nasal microbiota, nasal dysbiosis and neurodegenerative diseases (NDs). The respiratory airways usually act as a substratum place for the microbes and can act as the base for respiratory tract infections. The microbial metabolites and the microbes can cross the blood–brain barrier and may cause NDs, such as Parkinson’s disease (PD), Alzheimer’s disease (AD), and multiple sclerosis (MS). The scientific investigations on the potential role of the nasal microbiota in olfactory functions and the relationship between their dysfunction and neurological diseases are limited. Recently, the consequences of the severe acute respiratory syndrome coronavirus (SARS-CoV-2) in patients with neurological diseases are under exploration. The crosstalk between the gut and the nasal microbiota is highly influential, because their mucosal regions are the prominent microbial niche and are connected to the olfaction, immune regulation, and homeostasis of the central nervous system. Diet is one of the major factors, which strongly influences the mucosal membranes of the airways, gut, and lung. Unhealthy diet practices cause dysbiosis in gut microbiota and the mucosal barrier. The current review summarizes the interrelationship between the nasal microbiota dysbiosis, resulting olfactory dysfunctions, and the progression of NDs during aging and the involvement of coronavirus disease 2019 in provoking the NDs.

Can Supplemented Skim Milk (SKM) Boost Your Gut Health?

The incorporation of functional ingredients, such as prebiotics and probiotics in food matrices, became a common practice in the human diet to improve the nutritional value of the food product itself. Worldwide, skim milk (SKM) is one of the most consumed food matrices, comprising all the essential nutrients desired for a balanced diet. Thus, the modulation of the human gut microbiota by SKM supplemented with different well-known functional ingredients was evaluated. Four well-studied prebiotics, fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), mannan-oligosaccharides (MOS) and inulin, and one probiotic product, UL-250® (Saccharomyces boulardii) were added at 1% (w/v) to SKM and subjected to a gastrointestinal in vitro model. The impact of each combination on gut microbiota profile and their fermentation metabolites (i.e., short-chain fatty acids–SCFA) was assessed by quantitative polymerase chain reaction (qPCR) and high-performance liquid chromatography (HPLC), respectively. The addition of FOS to SKM had promising results, showing prebiotic potential by promoting the growth of Lactobacillus, Bifidobacterium, and Clostridium cluster IV. Moreover, the increment of SCFA levels and the decrease of total ammonia nitrogen were observed throughout colonic fermentation. Overall, these results demonstrate that the combination SKM + FOS was the most beneficial to the host’s health by positively modulating the gut microbiota.

The Role of Gut Microbiota in Neuropsychiatric Diseases – Creation of An Atlas-Based on Quantified Evidence

There is a growing body of evidence highlighting the significant role of gut microbiota in various pathologies. We performed a systematic review to review the different microbiota involved in neuropsychiatric diseases. 50 studies (23 studies for autism spectrum disorders, 18 for major depression, and 9 for schizophrenia), representing 2,137 patients and 2,844 controls. Concerning the microbiota, the genera Prevotella, Clostridium, Bacteroides, Bifidobacterium, Ruminococcus, Megamonas, and Faecalbacterium were the ones detected with the most frequent variation of their relatives abundance. We also assess the overlap between the different pathologies. This study provides new insights into the complex relationship between the brain and the gut and the implications in neuropsychiatric pathologies. The identification of unique signatures in neuropsychiatric diseases suggests new possibilities in targeted anti or probiotic treatment.

Microbiota medicine: towards clinical revolution

The human gastrointestinal tract is inhabited by the largest microbial community within the human body consisting of trillions of microbes called gut microbiota. The normal flora is the site of many physiological functions such as enhancing the host immunity, participating in the nutrient absorption and protecting the body against pathogenic microorganisms. Numerous investigations showed a bidirectional interplay between gut microbiota and many organs within the human body such as the intestines, the lungs, the brain, and the skin. Large body of evidence demonstrated, more than a decade ago, that the gut microbial alteration is a key factor in the pathogenesis of many local and systemic disorders. In this regard, a deep understanding of the mechanisms involved in the gut microbial symbiosis/dysbiosis is crucial for the clinical and health field. We review the most recent studies on the involvement of gut microbiota in the pathogenesis of many diseases. We also elaborate the different strategies used to manipulate the gut microbiota in the prevention and treatment of disorders. The future of medicine is strongly related to the quality of our microbiota. Targeting microbiota dysbiosis will be a huge challenge.

Organoid technologies for the study of intestinal microbiota–host interactions

Postbiotics have recently emerged as critical effectors of the activity of probiotics and, because of their safety profile, they are considered potential therapeutics for the treatment of fragile patients. Here, we present recent studies on probiotics and postbiotics in the context of novel discovery tools, such as organoids and organoid-based platforms, and nontransformed preclinical models, that can be generated from intestinal stem cells. The implementation of organoid-related techniques is the next gold standard for unraveling the effect of microbial communities on homeostasis, inflammation, idiopathic diseases, and cancer in the gut. We also summarize recent studies on biotics in organoid-based models and offer our perspective on future directions.

Role of pollution on the selection of antibiotic resistance and bacterial pathogens in the environment

There is evidence that human activity causes pollution that contributes to an enhanced selection of bacterial pathogens in the environment. In this review, we consider how environmental pollution can favour the selection of bacterial pathogens in the environment. We specifically discuss pollutants released into the environment by human activities (mainly human waste) that are associated with the selection for genetic features in environmental bacterial populations that lead to the emergence of bacterial pathogens. Finally, we also identify key pollutants that are associated with antibiotic resistance and discuss possibilities of how to prevent their release into the environment.