Gut Microbiota in Health and Disease

The influence of microbiota on the efficacy and toxicity of immunotherapy in cancer treatment

Immunotherapy, which uses the body's immune system to fight cancer cells, has gained attention recently as a breakthrough in cancer treatment. Although significant progress has been made, obstacles still exist since cancers are skilled at avoiding immune monitoring. The gut microbiota is being looked at more and more in modern research as a critical component in improving the results of immunotherapy. Through modulating both innate and adaptive immune responses, the gut microbiome has a significant impact on cancer immunotherapy. The effectiveness of treatment and the way the immune system responds are significantly influenced by some microorganisms and the metabolites they produce, especially short-chain fatty acids. On the other hand, dysbiosis and persistent inflammation in the gut environment might unintentionally accelerate the growth of tumors, which makes the complex relationship between the makeup of the microbiota and cancer treatment more challenging. Gut microbiota plays a crucial role in immunotherapy effectiveness. Improved microbial diversity leads to better treatment responses, with some taxa like Bacteroides and Ruminococcaceae being linked to better responses to immune checkpoint inhibitors. Dysbiotic conditions can worsen immune-related side effects and reduce treatment effectiveness. Strategies manipulating gut microbiota, such as fecal microbiota transplantation, antibiotic therapies, and dietary interventions, could optimize immunotherapy response and prognosis. However, standardizing these interventions for different cancer types and patient populations is challenging due to individual microbiome differences. Future research should combine microbiome research with AI and rigorous clinical trials for individualized cancer treatments.

Gut-brain axis and neuroplasticity in health and disease: a systematic review

The gut microbiota emerged as a potential modulator of brain connectivity in health and disease. This systematic review details current evidence on the gut-brain axis and its influence on brain connectivity. The initial set of studies included 532 papers, updated to January 2024. Studies were selected based on employed techniques. We excluded reviews, studies without connectivity focus, studies on non-human subjects. Forty-nine papers were selected. Employed techniques in healthy subjects included 15 functional magnetic resonance imaging studies (fMRI), 5 diffusion tensor imaging, (DTI) 1 electroencephalography (EEG), 6 structural magnetic resonance imaging, 2 magnetoencephalography, 1 spectroscopy, 2 arterial spin labeling (ASL); in patients 17 fMRI, 6 DTI, 2 EEG, 9 structural MRI, 1 transcranial magnetic stimulation, 1 spectroscopy, 2 R2*MRI. In healthy subjects, the gut microbiota was associated with connectivity of areas implied in cognition, memory, attention and emotions. Among the tested areas, amygdala and temporal cortex showed functional and structural differences based on bacteria abundance, as well as frontal and somatosensory cortices, especially in patients with inflammatory bowel syndrome. Several studies confirmed the connection between microbiota and brain functions in healthy subjects and patients affected by gastrointestinal to renal and psychiatric diseases.

Gut microbiome-gut brain axis-depression: interconnection

OBJECTIVES

The relationship between the gut microbiome and mental health, particularly depression, has gained significant attention. This review explores the connection between microbial metabolites, dysbiosis, and depression. The gut microbiome, comprising diverse microorganisms, maintains physiological balance and influences health through the gut-brain axis, a communication pathway between the gut and the central nervous system.

METHODS

Dysbiosis, an imbalance in the gut microbiome, disrupts this axis and worsens depressive symptoms. Factors like diet, antibiotics, and lifestyle can cause this imbalance, leading to changes in microbial composition, metabolism, and immune responses. This imbalance can induce inflammation, disrupt neurotransmitter regulation, and affect hormonal and epigenetic processes, all linked to depression.

RESULTS

Microbial metabolites, such as short-chain fatty acids and neurotransmitters, are key to gut-brain communication, influencing immune regulation and mood. The altered production of these metabolites is associated with depression. While progress has been made in understanding the gut-brain axis, more research is needed to clarify causative relationships and develop new treatments. The emerging field of psychobiotics and microbiome-targeted therapies shows promise for innovative depression treatments by harnessing the gut microbiome's potential.

CONCLUSIONS

Epigenetic mechanisms, including DNA methylation and histone modifications, are crucial in how the gut microbiota impacts mental health. Understanding these mechanisms offers new prospects for preventing and treating depression through the gut-brain axis.

Exploring the gut microbiome: A potential biomarker for cancer diagnosis, prognosis, and therapy

The gut microbiome, a complex community of trillions of microorganisms in the intestines, is crucial in maintaining human health. Recent advancements in microbiome research have unveiled a compelling link between the gut microbiome and cancer development and progression. Alterations in the composition and function of the gut microbiome, known as dysbiosis, have been implicated in various types of cancer, including, esophageal, liver, colon, pancreatic, and gastrointestinal. However, the specific gut microbial strains associated with the development or progression of cancers in various tissues remain largely unclear. Here, we summarize current research findings on the gut microbiome of multiple cancers. This review aims to identify key gut microbial targets that closely influence cancer development based on current research findings. To accurately evaluate the effectiveness of the gut microbiome as a clinical tool for cancer, further research is needed to explore its potential as a biomarker and therapeutic strategy.

Xenobiotic metabolism activity of gut microbiota from six marine species: Combined taxonomic, metagenomic, and in vitro transformation analysis

The xenobiotic metabolism driven by the gut microbiota significantly regulates the bioavailability and toxic effects of environmental pollutants such as plasticizers on aquatic organisms. However, it is still unknown whether the gut microbiota can exhibit variable metabolic ability across host species and which functional bacteria and genes are involved in xenobiotic transformation. This study investigated the enriched gut microbiota community composition and diversity of in vitro enrichment cultures from 6 marine species, namely, yellowfin seabream (Acanthopagrus latus), thorn fish (Terapon jarbua), shortnose ponyfish (Leiognathus brevirostris), mussel (Perna viridis), prawn (Parapenaeopsis hungerfordi) and crab (Charybdis riversandersoni). Pseudomonadota, Bacteroidota and Bacillota were the dominant phyla and Enterobacter, Raoultella, Klebsiella, Dysgonomanas and Lactococcus were the dominant genera in the enriched flora according to 16S rRNA sequencing. Furthermore, the metagenomic results revealed that all enriched gut microbiota presented metabolic genes for carbohydrates, amino acids, lipids, and xenobiotics. In particular, the gut microbiota of yellowfin seabream had the highest abundance of glycoside hydrolase family genes and CYP450 enzyme genes. Klebsiella was identified as a common potential degrader of xenobiotic metabolism. In addition, the Biolog plate test system confirmed that the gut microbiota can metabolize various carbon sources and drive the xenobiotic transformation. According to AWCD analysis of community level physiological profiling (CLPP), yellowfin seabream > mussel > prawn > shortnose ponyfish > crab > thorn fish. The gut microbiota of yellowfin seabream presented a stronger metabolic profile of phthalates and bisphenol analogs which reflected by their AWCD results and concentration variations. Overall, our results demonstrated the diverse metabolic abilities of the gut microbiota from six marine organisms and their potential for altering of the fate of xenobiotics in the ecosystem on the basis of combined taxonomic, metagenomic, and in vitro transformation analysis.

Short-sighted evolution of virulence for invasive gut microbes: From hypothesis to tests

Why microbes harm their hosts is a fundamental question in evolutionary biology with broad relevance to our understanding of infectious diseases. Several hypotheses have been proposed to explain this "evolution of virulence." In this perspective, we reexamine one of these hypotheses in the specific context of the human gut microbiome, namely short-sighted evolution. According to the short-sighted evolution hypothesis, virulence is a product of niche expansion within a colonized host, whereby variants of commensal microbes establish populations in tissues and sites where the infection causes morbidity or mortality. This evolution is short-sighted in that the evolved variants that infect those tissues and sites are not transmitted to other hosts. The specific hypothesis that we propose is that some bacteria responsible for invasive infections and disease are the products of the short-sighted evolution of commensal bacteria residing in the gut microbiota. We present observations in support of this hypothesis and discuss the challenges inherent in assessing its general application to infections and diseases associated with specific members of the gut microbiota. We then describe how this hypothesis can be tested using genomic data and animal model experiments and outline how such studies will serve to provide fundamental information about both the evolution and genetic basis of virulence, and the bacteria of intensively studied yet poorly understood habitats including the gut microbiomes of humans and other mammals.

Unveiling the complex interplay between gut microbiota and polycystic ovary syndrome: A narrative review

BACKGROUND & AIM

Polycystic Ovary Syndrome (PCOS) is a complex endocrine disorder that affects women throughout their reproductive age and characterised via polycystic ovaries, hyperandrogenism, and irregular menstruation. There is rising evidence that the pathophysiology of PCOS is significantly affected via the gut microbiota and its metabolic products.

METHODS

This narrative review synthesizes current literature exploring the relationship between gut microbiota and PCOS. A comprehensive search of electronic databases was conducted to identify relevant studies. Further this review also analysed therapeutic options of probiotics, prebiotics, Fecal Microbiota Transplant (FMT), high fiber and poly phenol rich diet and novel therapeutic agents in treatment of PCOS.

RESULTS

Emerging evidence suggests alterations in the composition and diversity of gut microbiota in women with PCOS. The current literature showed a complex relationship of gut microbiota, short chain fatty acids (SCFAs) metabolism, intestinal permeability and LPS (Lipid Polysaccharide) metabolism, gut-brain axis and bile acid (BA) pathway within etiology and pathophysiology of PCOS. Additionally, the factors such as diet, lifestyle, genetics, and environmental influences may all contribute to alterations in gut microbiota that could potentially exacerbate or mitigate PCOS symptoms.

CONCLUSION

The review provides valuable insights into the intricate interplay between the gut and female reproductive health. The present evidence suggested that alterations in diversity and function of the gut microbiota may lead to specific pathogenic changes that lead to development of PCOS. A comprehensive understanding of these microbial dynamics may lead to new therapeutic approaches that target the gut micro biome.

Metabolism of quercitrin in the colon and its beneficial regulatory effects on gut microbiota

BACKGROUND

Quercitrin is a dietary flavonoid widely found in plants with various physiological activities. However, whether quercitrin alters gut microbiota in vivo is not well understood. The aim of this study was to investigate metabolism of quercitrin in the colon and its regulation on gut microbiota in mice.

RESULTS

Herein, 22 flavonoids related to quercitrin metabolism were identified based on ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). Gas chromatography and 16S rDNA gene sequencing were used to investigate short-chain fatty acid (SCFA) content and diversity of composition of gut microbiota, respectively. The results showed that quercitrin significantly alters the beta-diversity of the gut microbiota, probiotics such as Akkermansia and Lactococcus were significantly increased, and the production of propanoate, isovalerate and hexanoate of the quercitrin group were enhanced significantly. The Spearman's association analysis provided evidence that Gardnerella and Akkermansia have obvious correlations with most of quercitrin metabolites and SCFAs.

CONCLUSION

Quercitrin and its metabolites in the colon altered the structure of the mice gut microbiota and increased the content of SCFAs. Our experiments provide valuable insights into quercitrin research and application. © 2024 Society of Chemical Industry.

Structural characterization, antioxidant activity, and fermentation characteristics of Flammulina velutipes residue polysaccharide degraded by ultrasonic assisted H2O2-Vc technique

Adhere to the concept of low-carbon environmental protection and turning waste into treasure, polysaccharides from Flammulina velutipes residue polysaccharide (FVRP) has been developed and possesses diverse bioactivities, comprising antioxidant, hypoglycemic, and relieving heavy metal damage, which still has the disadvantages of high molecular weight and low bioavailability. The current work is the first to prepare a degraded polysaccharide (FVRPV) from FVRP by ultrasonic assisted H2O2-Vc technique in order to reduce its molecular weight, thereby improving its activity and bioavailability. Our results found that the molecular weight and average particle size were declined, but the monosaccharide composition and characteristic functional group types of FVRPV had no impact. The structural changes of polysaccharides analyzed by XRD, Congo Red test, I2-KI, SEM, and methylation analysis indicated that the surface morphology and glycosidic bond composition of FVRPV possessed longer side chains and a greater number of branches with an amorphous crystal structure devoid of a triple helix configuration, and had experienced notable alterations after ultrasonic assisted H2O2-Vc treatment. Meanwhile, the in vitro antioxidant capacity of FVRPV had significantly increased compared to FVRP, implying ultrasonic assisted H2O2-Vc technique maybe a effective method to enhance the bioactivity of polysaccharides. In addition, the content of polysaccharide, reducing sugar, and uronic acid in FVRPV was significantly decreased, but antioxidant capacity of fermentation broth was stronger by in vitro human fecal fermentation. The 16S rDNA sequencing data displayed that FVRPV can enrich probiotics and reduce the abundance of pathogenic bacteria through different metabolic pathways mediated by gut microbiota, thereby exerting its potential probiotic effects. The interesting work provides a novel degraded polysaccharide by ultrasonic assisted H2O2-Vc technique, laying a foundation for developing FVRPV as a new antioxidant and prebiotic.

Causal Relationship Between Gut Microbiota and Leukemia: Future Perspectives

The gut microbiota plays a crucial role in maintaining homeostasis in the human gastrointestinal tract. Numerous studies have shown a strong association between the gut microbiota and the emergence and progression of various diseases. Leukemia is one of the most common hematologic malignancies. Although standardized protocols and expert consensus have been developed for routine diagnosis and treatment, limitations remain due to individual differences. Nevertheless, a large number of studies have established a link between the gut microbiota and leukemia, with disturbances in the gut microbiota directly or indirectly affecting the development of leukemia. However, the causal relationship between the two remains unclear, and studying and exploring the causal relationship may open up entirely new avenues and protocols for use in the prevention and/or treatment of leukemia, offering new insights into diagnosis and treatment. In this review, the intricate relationship between the gut microbiota and leukemia is explored in depth, including causal associations, metabolite effects, therapeutic applications, and complications. Based on the characteristics of the gut microbiota, the future applications and prospects of gut microbiota are discussed to provide useful information for clinical treatment of leukemia.

Relevance of Indian Traditional Herbal Brews for Gut Microbiota Balance

The considerable changes in lifestyle patterns primarily affect the human gut microbiota and result in obesity, diabetes, dyslipidemia, renal complications, etc. though there are few traditional safeguards such as herbal brews to maintain the ecological stability under intestinal dysbiosis. The present article is designed to collect all the scientific facts in a place to decipher the role of the Indian traditional herbal brews used to balance gut health for centuries. Computerized databases, commercial search engines, research papers, articles, and books were used to search by using different keywords to select the most appropriate published articles from 2000 onward to September 2023. A total of 1907 articles were scrutinized, 46 articles were finally selected from the 254 screened, and targeted information was compiled. Interaction of herbal brews to the gut microflora and resulting metabolites act as prebiotics due to antimicrobial, anti-inflammatory, and antioxidant properties, and modulate the pH of the gut. The effect of brews on gut microbiota has a drastic impact on various gut-related diseases and has gained popularity as an alternative to antibiotics against bacteria, fungi, viruses, parasites, and boosting the immune system and strengthening the intestinal barrier. Berberine, kaempferol, piperine, and quercetin have been found in more than one brew discussed in the present article. Practically, these brews balance the gut microbiota, prevent chronic and degenerative diseases, and reduce organ inflammation, though, there is a knowledge gap on the molecular mechanism to explain their efficacy. Indian traditional herbal brews used to reboot and heal the gut microbiota since centuries-old practice with successful history without toxicity. The systematic consumption of these brews under specific dietary prescriptions has a hope of arrays for a healthy human gut microbiome in the present hasty lifestyle with overall health and well-being.

Graphical Abstract

Multifrequency-STD NMR unveils the first Michaelis complex of an intramolecular trans-sialidase from Ruminococcus gnavus

RgNanH is an intramolecular trans-sialidase expressed by the human gut symbiont Ruminococcus gnavus, to utilise intestinal sialylated mucin glycan epitopes. Its catalytic domain, belonging to glycoside hydrolase GH33 family, cleaves off terminal sialic acid residues from mucins, releasing 2,7-anhydro-Neu5Ac which is then used as metabolic substrate by R. gnavus to proliferate in the mucosal environment. RgNanH is one of the three intramolecular trans-sialidases (IT-sialidases) characterised to date, and the first from a gut commensal organism. Here, saturation transfer difference NMR (STD NMR) in combination with computational techniques (molecular docking and CORCEMA-ST) were used to elucidate the specificity, kinetics and relative affinity of RgNanH for sialoglycans and 2,7-anhydro-Neu5Ac. We propose the first 3D model for the Michaelis complex of an IT-sialidase. This confirms the sialic acid to be the main recognition element for the interaction in the enzymatic cleft and highlights the crucial role of Trp698 to make CH-π stacking with the galactose residue of the substrate 3'-sialyllactose. The same contact is shown not to be possible for 6'-sialyllactose, due to geometrical constrains of the α-2,6 linkage. Indeed 6'-sialyllactose is not a substrate, even though it is shown to bind to RgNanH by STD NMR. These findings corroborate the role of Trp698 for the α-2,3 specificity of IT-sialidases. In this structural study, the use of Differential Epitope Mapping STD NMR (DEEP-STD NMR) approach allowed the validation of the proposed 3D models in solution. These structural approaches are shown to be instrumental in shedding light on the molecular mechanisms underpinning enzymatic reactions in the absence of enzyme-substrate X-ray structures.

The gut microbiome and the brain

PURPOSE OF REVIEW

The importance of the gut microbiome for human health and well-being is generally accepted, and elucidating the signaling pathways between the gut microbiome and the host offers novel mechanistic insight into the (patho)physiology and multifaceted aspects of healthy aging and human brain functions.

RECENT FINDINGS

The gut microbiome is tightly linked with the nervous system, and gut microbiota are increasingly emerging as important regulators of emotional and cognitive performance. They send and receive signals for the bidirectional communication between gut and brain via immunological, neuroanatomical, and humoral pathways. The composition of the gut microbiota and the spectrum of metabolites and neurotransmitters that they release changes with increasing age, nutrition, hypoxia, and other pathological conditions. Changes in gut microbiota (dysbiosis) are associated with critical illnesses such as cancer, cardiovascular, and chronic kidney disease but also neurological, mental, and pain disorders, as well as chemotherapies and antibiotics affecting brain development and function.

SUMMARY

Dysbiosis and a concomitant imbalance of mediators are increasingly emerging both as causes and consequences of diseases affecting the brain. Understanding the microbiota's role in the pathogenesis of these disorders will have major clinical implications and offer new opportunities for therapeutic interventions.

Autism Spectrum and gastrointestinal health: Screening on the influence of environmental factors on gastrointestinal problems

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that combines genetic and environmental factors. The human microbiota is colonized by permanent or transitory microorganisms, depending on the host and the external factors controlling their permanence. The composition of the gut microbiota (GM) in ASD individuals is notably different from that in controls, which may contribute to the clinical conditions observed in these individuals. This study aimed to indirectly investigate the influence of GM on the gut-brain axis in individuals with ASD and controls by analyzing environmental factors that contribute to the microbiota composition. Two questionnaires were designed to collect data, one for the ASD Group (ASDG) and the other one for the Control Group (CG). The raw data from both questionnaires were collected from 2772 respondents. After triage, answers from 1687 ASD individuals, along with 466 respondents from the CG, were analyzed, resulting in a total of 2237 respondents. Our results showed that gastrointestinal problems (GP) escalate as individuals age and become more prominent in ASD individuals. In contrast, feeding problems (FP) did not appear to escalate in either group as individuals aged, even though the FP decreased in the CG. ANOVA revealed significant differences in breastfeeding status compared to GPs among preterm control individuals born via cesarean section (p-value = 0.027). The mean values of GP for breastfed and nonbreastfed individuals, for ASDG (0.257; 0.268) and CG (0.105; 0.248), highlighted the differences in breastfeeding effects on GP for the study groups. The use of antibiotics during pregnancy seemed to be significant for GPs in the ASDG only for breastfed individuals (p-value <0.001), but not in the CG group. In conclusion, variables such as mode of delivery, FPs, type of birth, and length of breastfeeding do not seem to be determining factors for GP in the ASDG but are relevant for the CG. However, for ASDG individuals whose mothers took antibiotics during pregnancy, breastfeeding may act as a protective factor, as maternal antibiotic administration during pregnancy seems to aggravate GP-values across the ages of the participants. Considering GP as a proxy for GM and recognizing the importance of GM composition for central nervous system (CNS) function, it appears that in individuals with ASD, GM seems to be more dependent on other factors, which might be linked to the genetic background of each one. These findings suggest that future studies of the gut-brain axis in individuals with ASD might consider the individual's genetic background, environmental factors, and GM.

The Mechanism of Relieving Diarrheal Irritable Bowel Syndrome Using Polyphenols from Ribes nigrum L. Based on a Network Pharmacology Analysis and 16S rRNA Sequencing

Diarrheal irritable bowel syndrome (IBS-D) is a chronic bowel condition that leads to intestinal dysfunction and is typically accompanied by diarrhea, stomach pain, and abdominal distension. Ribes nigrum L. polyphenols (RNPs), which are natural plant polyphenols, are the subject of this study, which aims to assess their potential in improving IBS-D and to explore the underlying mechanisms through a network pharmacology analysis and 16S rRNA sequencing. Next, mice models of diarrhea-predominant irritable bowel were established, and the mice with IBS-D were treated with RNPs. The effect of RNPs was then evaluated in terms of body weight, abdominal withdrawal reflex (AWR), Bristol score, fecal water percentage, diluted fecal volume, total intestinal transit time, immune index, histopathological observation, and changes in inflammatory factors. Finally, 16S rRNA sequencing and reverse q-RTPCR were utilized to evaluate the components that mediate the impact of RNPs on IBS-D. It was found that when RNP treatment was administered to mice with IBS-D, they decreased the water content in their stools, raised their immunological scores, and decreased the amount of inflammatory substances in their bodies. Moreover, through 16S rRNA sequencing, it was shown that the RNP treatment increased the relative abundances of Bacteroides, Alloprevotella, and Alistipes, which led to the remodeling of gut microbiota. In summary, RNPs significantly improved the conditions of mice with IBS-D by inhibiting the FoxO pathway and enhancing gut microbiota. This study concludes that RNPs could significantly improve the symptoms of mice with IBS-D through these means.

Intestinal microbiota, probiotics and their interactions with drugs: knowledge, attitudes and practices of health science students in Serbia

BACKGROUND

Acquiring sufficient knowledge and understanding the importance of intestinal microbiota and probiotics in health and disease, as well as their potential for interactions with concurrently administered drugs, can significantly influence future pharmacotherapeutic practices among health science students.

OBJECTIVE

This study aimed to assess the knowledge, factors influencing knowledge, attitudes, and practices regarding intestinal microbiota and probiotics and their interactions with drugs among students of the Faculty of Medicine in Novi Sad.

MATERIALS AND METHODS

This cross-sectional study was conducted in the form of an anonymous questionnaire among first- and final-year medical and pharmacy students. Predictors of knowledge scores were analyzed using a negative binomial regression model.

RESULTS

The questionnaire was completed by 263 medical and pharmacy students (44.58% first-year and 55.5% final-year students). Approximately half of the students (53.2%) demonstrated fair knowledge, 34.2% had poor knowledge, and only 12.5% had good knowledge about the intestinal microbiota and probiotics. Study year and self-assessment of knowledge were statistically significant predictors of knowledge scores, while the presence of chronic diseases, previous education, and lifestyle were not. The most common indications for probiotic use among respondents were antibiotic use (75.4%) and gastrointestinal symptoms (69.9%). A large number of respondents reported not paying attention to the concurrent use of probiotics with drugs or food, nor to the choice of specific probiotic strains. Most students expressed that they receive insufficient information on this topic at the university.

CONCLUSION

Most students demonstrate inadequate knowledge about the gut microbiota and probiotics, which affects their practical use of these supplements. The primary reasons for this are insufficient information and unreliable sources of information. Therefore, enhancing education on this topic could significantly improve the knowledge and pharmacotherapeutic practices of future healthcare professionals.

Nutrigenomics and neurological disorders: exploring diet-brain interactions for cognitive health

This review article investigates the intricate relationship between nutrigenomics and neurological disorders, highlighting how genetic variations affect an individual's response to nutrients. The study delves into the role of diet-related oxidative stress and the gut-brain axis in the progression and management of brain disorders such as Parkinson's disease, Alzheimer's disease, epilepsy, stroke, migraines, and depression. The review encompasses various clinical trials and introduces new trends and techniques, including omics and artificial intelligence, in identifying and managing neurological disorders. The main findings emphasize that personalized diet recommendations, tailored to an individual's genetic makeup, can significantly improve cognitive health and manage neurological conditions. The study concludes that further research in the field of nutrigenomics is essential to advancing personalized nutrition strategies for better neurological functioning, ultimately linking diet, genes, and brain health.

Chronic constipation and gut microbiota: current research insights and therapeutic implications

Chronic constipation is a prevalent clinical condition. Its etiology and pathogenesis have not yet been fully understood. In recent years, mounting evidence suggests a close association between chronic constipation and intestinal dysbiosis, including alterations in the colony structure and metabolites, as well as the modulation of bowel movements via the brain-gut-microbiota axis. With the deepening of related research, probiotic-related therapies are expected to become a potential first-line treatment for chronic constipation in the future. In this review, we summarize the current research insights into the intricate relationships between chronic constipation and the gut microbiota and briefly discuss several different approaches for treating chronic constipation. The findings from this review may advance our understanding of the pathological mechanisms underlying chronic constipation and, ultimately, translate them into improvements in patient care.

Microbiota and social behavior alterations in a mouse model of down syndrome: Modulation by a synbiotic treatment

Sex differences in the composition and functionality of gut microbiota are an emerging field of interest in neurodevelopmental disorders, as they may help in understanding the phenotypic disparities between males and females. This study aimed to characterize sex-related specific alterations in gut microbiota composition in a mouse model of Down syndrome (Ts65Dn mice, TS mice) through the sequencing of the PCR-amplified 16S ribosomal DNA fraction. Moreover, it intended to examine whether the modulation of gut microbiota by the administration of a synbiotic (SYN) treatment would be beneficial for the behavioral alterations observed in male and female TS mice. Our results show that male, but not female, TS mice exhibit alterations in beta diversity compared to their wild-type (WT) littermates. Sex-dependent differences are also observed in the relative abundance of the classes Bacilli and Clostridia. Administering the SYN effectively counteracts hypersociability in females, and normalizes the overall abundance of Bacilli, specifically by increasing Lactobacillaceae. On the contrary, it rescues emotional recognition deficits in male TS mice and increases the relative abundance of the families Lactobacillaceae, Streptococcaceae and Atopobiaceae. In addition, a metagenome KEGG analysis of differentially enriched pathways shows relevant changes in the cofactor biosynthesis and the amino acid synthesis categories. Finally, following SYN treatment, both male and female TS mice exhibit a robust increase in propionic acid levels compared to WT littermates. These findings suggest sex-specific mechanisms that could link gut microbiota composition with behavior in TS mice, and underscore the potential of targeted gut microbiota interventions to modulate social abnormalities in neurodevelopmental disorders.

Modulation of Canine Gut Microbiota by Prebiotic and Probiotic Supplements: A Long-Term In Vitro Study Using a Novel Colonic Fermentation Model

The gut microbiota plays a crucial role in dogs' health, influencing immune function, digestion, and protection against pathogens. This study evaluates the effects of three canine dietary supplements-Microbiotal (prebiotic), Lactobacillus reuteri (probiotic), and a combination of both-on the gut microbiota composition of a healthy canine donor using an in vitro colonic fermentation model. The SCIME™ platform, adapted to simulate the canine gastrointestinal tract, was used to monitor microbial shifts in the luminal and mucosal environments of the proximal and distal colon over a 2-week treatment period. The microbial communities were analyzed using 16S rRNA sequencing to assess changes at various taxonomic levels. Alpha- and beta-diversity indices were calculated, while LEfSe and treeclimbR were employed to identify taxa-driving microbial shifts. Results indicated that all treatments led to significant modulations in key microbial groups, with enrichment of Limosilactobacillus, Bifidobacterium, Prevotella, and Faecalibacterium. These changes suggest improved saccharolytic fermentation and butyrate production, particularly when prebiotics and probiotics were co-administered. This study highlights the promising benefits of combined prebiotic and probiotic supplementation in promoting gut health and microbial diversity, providing a basis for future studies targeting the metabolic activity of the gut microbiota using the same supplements and technology.

Local and systemic effects of microplastic particles through cell damage, release of chemicals and drugs, dysbiosis, and interference with the absorption of nutrients

Microplastic particles (MPs) have been detected in a variety of environmental samples, including soil, water, food, and air. Cellular studies and animal exposures reported that exposure to MPs composed of different polymers might result in adverse effects at the portal of entry (local) or throughout the body (systemic). The most relevant routes of particle uptake into the body are oral and respiratory exposure. This review describes the various processes that may contribute to the adverse effects of MPs. Only MPs up to 5 µm were found to cross epithelial barriers to a significant extent. However, MPs may also exert a detrimental impact on human health by acting at the epithelial barrier and within the lumen of the orogastrointestinal and respiratory tract. The potential for adverse effects on human health resulting from the leaching, sorption, and desorption of chemicals, as well as the impact of MPs on nutritional status and dysbiosis, are reviewed. In vitro models are suggested as a means of (1) assessing permeation, (2) determining adverse effects on cells of the epithelial barrier, (3) examining influence of digestive fluids on leaching, desorption, and particle properties, and (4) role of microbiota-epithelial cell interactions. The contribution of these mechanisms to human health depends upon exposure levels, which unfortunately have been estimated very differently.

Human microbiota peptides: important roles in human health

Covering: 1974 to 2024Human microbiota consist of a diverse array of microorganisms, such as bacteria, Eukarya, archaea, and viruses, which populate various parts of the human body and live in a cooperatively beneficial relationship with the host. They play a crucial role in supporting the functional balance of the microbiome. The coevolutionary progression has led to the development of specialized metabolites that have the potential to substitute traditional antibiotics in combating global health challenges. Although there has been a lot of research on the human microbiota, there is a considerable lack of understanding regarding the wide range of peptides that these microbial populations produce. Particularly noteworthy are the antibiotics that are uniquely produced by the human microbiome, especially by bacteria, to protect against invasive infections. This review seeks to fill this knowledge gap by providing a thorough understanding of various peptides, along with their in-depth biological importance in terms of human disorders. Advancements in genomics and the understanding of molecular mechanisms that control the interactions between microbiota and hosts have made it easier to find peptides that come from the human microbiome. We hope that this review will serve as a basis for developing new therapeutic approaches and personalized healthcare strategies. Additionally, it emphasizes the significance of these microbiota in the field of natural product discovery and development.

Indigenous gut microbiota constitutively drive release of ciliary neurotrophic factor from mucosal enteric glia to maintain the homeostasis of enteric neural circuits

It has recently become clear that the gut microbiota influence intestinal motility, intestinal barrier function, and mucosal immune function; therefore, the gut microbiota are deeply involved in the maintenance of intestinal homeostasis. The effects of the gut microbiota on the enteric nervous system (ENS) in the adult intestine, however, remain poorly understood. In the current study, we investigated the effects of the gut microbiota on the ENS. Male C57BL/6 SPF mice at 12 weeks of age were given a cocktail of four antibiotics (ABX) orally to induce dysbiosis (ABX mice). As early as six hours after ABX administration, the weight of the cecum of ABX mice increased to be significantly greater than that of vehicle-treated animals; moreover, ABX-induced dysbiosis reduced the density of enteric nerve fibers (marked by tubulin-β3 immunoreactivity) in the lamina propria of the proximal colon to approximately 60% that of control. TAK242, a TLR4 antagonist, significantly lowered the nerve fiber density in the lamina propria of the proximal colonic mucosa to approximately 60% that of vehicle-treated SPF mice. We thus developed and tested the hypothesis that mucosal glia expressing TLR4 are activated by enteric bacteria and release neurotrophic factors that contribute to the maintenance of enteric neural circuits. Neurotrophic factors in the mucosa of the SPF mouse proximal colon were examined immunohistochemically. Ciliary neurotrophic factor (CNTF) was abundantly expressed in the lamina propria; most of the CNTF immunoreactivity was observed in mucosal glia (marked by S100β immunoreactivity). Administration of CNTF (subcutaneously, 0.3 mg/kg, 3 doses, 2 hours apart) to ABX mice significantly increased mucosal nerve fiber density in the ABX mouse proximal colon to nearly control levels. The effect of CNTF on enteric mucosal nerve fibers was examined in isolated preparations of proximal colon of ABX mice. As it did in vivo, exposure to CNTF in vitro significantly increased enteric mucosal nerve fiber density in the ABX-treated colon. In conclusion, our evidence suggests that gut microbiota constitutively activate TLR4 signaling in enteric mucosal glia, which secrete CNTF in response. The resulting bacterial-driven glial release of CNTF helps to maintain the integrity of enteric mucosal nerve fibers.

Revolutionizing IBD research with on-chip models of disease modeling and drug screening

Inflammatory bowel disease (IBD) comprises chronic inflammatory conditions with complex mechanisms and diverse manifestations, posing significant clinical challenges. Traditional animal models and ethical concerns in human studies necessitate innovative approaches. This review provides an overview of human intestinal architecture in health and inflammation, emphasizing the role of microfluidics and on-chip technologies in IBD research. These technologies allow precise manipulation of cellular and microbial interactions in a physiologically relevant context, simulating the intestinal ecosystem microscopically. By integrating cellular components and replicating 3D tissue architecture, they offer promising models for studying host-microbe interactions, wound healing, and therapeutic approaches. Continuous refinement of these technologies promises to advance IBD understanding and therapy development, inspiring further innovation and cross-disciplinary collaboration.

Curcumin-loaded polysaccharide microparticles alleviated DSS-induced ulcerative colitis by improving intestinal microecology and regulating MAPK/NF-κB/Nrf2/NLRP3 pathways

Curcumin (Cur) exerts many benefits on the host, but its application is limited by its poor bioavailability. In this study, composite polysaccharide microparticles loading Cur (Cur-CPM) was prepared by food-grade materials and gel technology. Its properties were analyzed via the in vitro and in vivo models, and then its benefit on gut health was assessed in DSS-treated mice. Compared to free Cur, CPM extended the residence time and absorption efficiency of Cur in the intestine, effectively ameliorating the symptoms of colitis. Cur-CPM alleviated colonic inflammation by inhibiting the activation of the MAPK and NF-κB pathways and suppressing NLRP3 inflammasome activity, affecting the expression of inflammation-related cytokines and mediators. In addition, Cur-CPM regulated the levels of antioxidants and oxidants in the colon tissues via Nrf2 activation, alleviating oxidative stress. Cur-CPM protected gut barrier function by maintaining the integrity of colonic mucosal layer and tight junction. The underlying mechanism can be attributed not only to the anti-inflammatory and antioxidant activities of Cur but also to modulation of Cur and CPM on the gut microbiota and metabolites. It suggests that Cur-CPM holds the potential to be developed as a functional component to enhance gut health.

Comprehensive evaluation of Flammulina velutipes residues polysaccharide based on in vitro digestion and human fecal fermentation

Flammulina velutipes residues (FVR) are the waste culture medium derived from the collection of Flammulina velutipes fruiting bodies, with an annual output that remains largely unexplored. The characteristics of digestion and fermentation of Flammulina velutipes residues polysaccharide (FVRP) are still relatively unknown. This study investigated the structure of the gut microbiota through 16 s rDNA gene sequencing and analyzed changes in short-chain fatty acid (SCFA) content via targeted metabolome analysis. The aim was to explore the prebiotic activity of FVRP based on a simulated digestion model combined with an in vitro anaerobic fermentation model. The results demonstrated that FVRP did not exhibit significant changes during in vitro digestion and fermentation but did enhance antioxidant activity. Furthermore, FVRP was found to rapidly reduce the pH value and increase SCFA production in the fermentation broth from lactic acid bacteria and human feces. Notably, FVRP altered the gut microbiota structure, significantly increasing the relative abundance of Firmicutes and Bacteroidota. Thus, FVRP could be considered a promising prebiotic food and feed additive that promotes the generation of short-chain fatty acids by modulating gut microbiota.

Inulin alleviates inflammatory response and gut barrier dysfunction via modulating microbiota in lipopolysaccharide-challenged broilers

This study was conducted to explore the protective effects of inulin against lipopolysaccharide (LPS)-induced inflammatory response and intestinal barrier dysfunction in broilers. 108 broilers were allocated to 3 treatments: 1) non-challenged broilers (Control, CON); 2) LPS-challenged broilers (LPS); 3) LPS-challenged broilers fed the basal diet supplemented with 15 g/kg of inulin (Inulin + LPS). At 21 d of age, the LPS-challenged groups received an intraperitoneal injection of LPS, and the CON group received an equal volume of saline. After 4 h of LPS exposure, samples of blood, intestinal mucosa and cecal digesta were collected. The results showed that LPS challenge induced systemic inflammation and damaged intestinal barrier function, whereas inulin attenuated LPS-induced production of pro-inflammatory cytokines by inhibiting the activation of TLR4 and NF-κB p65, and enhanced intestinal barrier function. In addition, LPS stimulation caused cecal microbial dysbiosis as shown by increased abundance of pathogenic bacteria including Ruminococcus_torques_group, Escherichia-Shigella and Subdoligranulum, while supplementation of inulin increased abundance of beneficial bacteria Faecalibacterium and Anaeroplasma, and metabolite production including propionate and butyrate concentrations. In conclusion, dietary supplementation of inulin could partially alleviate LPS-induced inflammation and intestinal barrier injury by modulating intestinal microbiota, thereby minimizing growth retardation of broilers. Our results provide a basis for the rational utilization of inulin in alleviating immune stress in broiler production.

Fibrolytic efficiency of the large intestine microbiota may benefit running speed in French trotters: A pilot study

This pilot study sought to explore the contribution of the large intestine microbiota to energy metabolism and exercise performance through its ability to degrade fibers into short-chain fatty acids (SCFAs). To investigate this, a correlational study was carried out on athlete horses under the same management conditions. Fecal microbiota diversity and composition, fibrolytic efficiency and SCFAs were analyzed. An incremental running test was carried out to estimate the maximal running speed (MRS) of the horses, and blood samples were taken to measure energy metabolism parameters. MRS was positively correlated with the efficiency of the fecal microbiota in degrading cellulose in vitro (r = 0.51; p = 0.02). The abundance of fibrolytic bacterial taxa was not associated with MRS, but functional inference analysis revealed a positive association between MRS and pathways potentially related to fibrolytic activity (r = 0.54; p = 0.07 and r = 0.56; p = 0.05 for butyrate metabolism and thiamine metabolism, respectively). In contrast, the metabolic pathway of starch degradation appeared negatively associated with MRS (r = -0.55; p = 0.06). The present findings suggest a potential contribution of the large intestine microbiota and dietary fibers digestion to exercise capacity in equine athletes.

Flavonoids, gut microbiota and cardiovascular disease: Dynamics and interplay

Cardiovascular disease (CVD) remains the leading cause of global morbidity and mortality. Extensive efforts have been invested to explicate mechanisms implicated in the onset and progression of CVD. Besides the usual suspects as risk factors (obesity, diabetes, and others), the gut microbiome has emerged as a prominent and essential factor in the pathogenesis of CVD. With its endocrine-like effects, the microbiome modulates many physiologic processes. As such, it is not surprising that dysbiosis-by generating metabolites, inciting inflammation, and altering secondary bile acid signaling- could predispose to or aggravate CVD. Nevertheless, various natural and synthetic compounds have been shown to modulate the microbiome. Prime among these molecules are flavonoids, which are natural polyphenols mainly present in fruits and vegetables. Accumulating evidence supports the potential of flavonoids in attenuating the development of CVD. The ascribed mechanisms of these compounds appear to involve mitigation of inflammation, alteration of the microbiome composition, enhancement of barrier integrity, induction of reverse cholesterol transport, and activation of farnesoid X receptor signaling. In this review, we critically appraise the methods by which the gut microbiome, despite being essential to the human body, predisposes to CVD. Moreover, we dissect the mechanisms and pathways underlying the cardioprotective effects of flavonoids.

Christensenella minuta mitigates behavioral and cardiometabolic hallmarks of social defeat stress

Psychological stress during early development and adolescence may increase the risk of psychiatric and cardiometabolic comorbidities in adulthood. The gut microbiota has been associated with mental health problems such as depression and anxiety and with cardiometabolic disease, but the potential role of the gut microbiota in their comorbidity is not well understood. We investigated the effects and mode of action of the intestinal bacterium Christensenella minuta DSM 32891 on stress-induced mental health and cardiometabolic disturbances in a mouse model of social defeat stress. We demonstrate that administered C. minuta alleviates chronic stress-induced depressive, anxiogenic and antisocial behavior. These effects are attributed to the bacterium's ability to modulate the hypothalamic-pituitary-adrenal axis, which mediates the stress response. This included the oversecretion of corticosterone and the overexpression of its receptors, as well as the metabolism of dopamine (DA) and the expression of its receptors (D1, D2L and D2S). Additionally, C. minuta administration reduced chronically induced inflammation in plasma, spleen and some brain areas, which likely contribute to the recovery of physical and behavioral function. Furthermore, C. minuta administration prevented chronic stress-induced cardiovascular damage by regulating key enzymes mediating liver fibrosis and oxidative stress. Finally, C. minuta increased the abundance of bacteria associated with mental health. Overall, our study highlights the potential of microbiota-directed interventions to alleviate both the physical and mental effects of chronic stress.

Molecular Mechanism for Malignant Progression of Gastric Cancer Within the Tumor Microenvironment

Gastric cancer (GC) is one of the most common cancers worldwide. Most patients are diagnosed at the progressive stage of GC, and progress in the development of effective anti-GC drugs has been insufficient. The tumor microenvironment (TME) regulates various functions of tumor cells, and interactions between the cellular and molecular components of the TME-e.g., inflammatory cells, fibroblasts, vasculature cells, and innate and adaptive immune cells-promote the aggressiveness of cancer cells and dissemination to distant organs. This review summarizes the roles of various TME cells and molecules in regulating the malignant progression and metastasis of GC. We also address the important roles of signaling pathways in mediating the interaction between cancer cells and the different components of the GC TME. Finally, we discuss the implications of these molecular mechanisms for developing novel and effective therapies targeting molecular and cellular components of the GC TME to control the malignant progression of GC.

Neuronutrition and Its Impact on Post-Stroke Neurorehabilitation: Modulating Plasticity Through Diet

The recovery of neurological deficits after ischemic stroke largely depends on the brain's ability to reorganize its undamaged neuronal circuits and neuronal plasticity phenomena. The consolidated evidence highlights the involvement of the patient's impaired nutritional conditions in post-stroke recovery and unsatisfying rehabilitative outcomes. Standardized nutritional protocols usually applied in hospitalized patients in a rehabilitation setting aim mainly to improve the general health conditions of patients, do not consider the high inter-individual variability in neurorehabilitation outcomes, and are not sufficiently modifiable to provide neuroprotective and restorative dietary patterns that could promote neuronal plasticity and functional recovery during neurorehabilitation. Neuronutrition, an emergent scientific field of neuroscience, represents a valid model of a personalized nutritional approach, assuring, for each patient, nutrients having antioxidant and anti-inflammatory properties, ensuring a balanced microbiota composition, and providing adequate neurotrophic support, essential for improving neuronal plasticity, brain functional recovery, and rehabilitative outcomes. In the present narrative review, we provide an overview of the current knowledge on neuronutrition as an adjuvant strategy of a personalized nutritional approach potentially effective in improving post-stroke neuroplasticity and neurorehabilitation by counteracting or at least limiting post-stroke oxidative/nitrosative stress, neuroinflammation, and gut-brain axis disturbance.

Probiotics and Prebiotics for the Treatment of Irritable Bowel Syndrome-A Narrative Review

Background/Objectives: Gastrointestinal functional disorders (GFDs), including irritable bowel syndrome (IBS), are imbalances in the gut-brain axis characterized by persistence of symptoms in the abdominal area. Probiotics are live microorganisms that provide benefits to the health of their hosts when administered in adequate amounts, while prebiotics are a substrate that is selectively used by host microorganisms. This narrative review aimed to evaluate the effectiveness of prebiotics and probiotics mostly in irritable bowel syndrome, particularly on issues such as the interaction between these products and the gut microbiota, the duration of supplementation and long-term effects, the definition of ideal dosages, and the regulation and quality control of these products. Methods: A bibliographic search was carried out in indexed databases and articles published within 10 years before the beginning of the study and publications in English language, which investigated the specific theme of the study were considered. Papers dealing with topics not covered by the research questions, or presenting errors related with the wrong population or the wrong methods, as well as experimental studies and case reviews were excluded. Fifty-five articles were selected, initially in isolation by the authors and, afterward, under consensus. Results: It was possible to observe the effectiveness mainly of probiotics, in improving specific symptoms of the respective disorder; however, the available data remain unclear due to limitations concerning samples and methods of the studies evaluated. Conclusions: Despite evidence suggestive of therapeutic efficacy, additional multicenter randomized controlled trials (RCTs) with better defined protocols are still necessary to fill in the gaps in this subject, define measures to ensure the safe administration of these products, and confirm their therapeutic potential.

Association between small intestine bacterial overgrowth and psychiatric disorders

Small intestinal bacterial overgrowth (SIBO) is a gastrointestinal condition characterized by abnormal colonization of bacteria in the small intestine, leading to overgrowth and alteration, which is linked to gastrointestinal issues, potentially affecting neurological and mental health. Despite existing research, we still do not understand how SIBO affects tryptophan metabolism and psychiatric diseases. We investigated the literature for connections between SIBO, tryptophan metabolism disruptions, and psychiatric disorders like autism, schizophrenia, Alzheimer's, and Parkinson's diseases. We also explored the interaction between thyroid disorders and their influence on SIBO and psychiatric illnesses. PubMed and Google Scholar databases were searched using keywords and phrases, individual and in combinations, like "SIBO," "gut microbiota," "neurologic disorders," "mental disorders," "tryptophan," "dopamine," and "thyroid disease." We focused on original research and review papers that presented empirical studies conducted on animal models and human subjects published in English between February 1992 to February 2023. The initial 2 634 534 records were preliminary screened based on title and abstract and then subjected to full-text review to exclude publications with insufficient data on SIBO, lack of a psychiatric disorder component, or methodological limitations compromising the integrity of the findings. The analysis highlights the significance of the association between psychiatric disorders and SIBO, emphasizing the role of gut-microbial diversity in mental health. We advocate for more detailed studies, including longitudinal research, to clarify the causal relationships between SIBO, gut dysbiosis, and psychiatric disorders and for an integrated approach while treating complex psychiatric conditions.

From microbes to mind: germ-free models in neuropsychiatric research

The gut-microbiota-brain axis refers to the bidirectional communication system between the gut, its microbial community, and the brain. This interaction involves a complex interplay of neural pathways, chemical transmitters, and immunological mechanisms. Germ-free animal models have been extensively employed to investigate gut-microbiota-brain interactions, significantly contributing to our current understanding of the role of intestinal microbes in brain function. However, despite the many benefits, this absence of microbiota is not futile. Germ-free animals present physiological and neurodevelopmental alterations that can persist even after reconstitution with normal microbiota. Therefore, the main goal of this minireview is to discuss how some of the inherent limitations of this model can interfere with the conclusion obtained when using these animals to study the complex nature of neuropsychiatric disorders. Furthermore, we examine the inclusion and use of antibiotic-based treatments as an alternative in the research of gut-brain interactions.

Dectin-1 as a therapeutic target for inflammatory bowel disease

Inflammatory bowel disease (IBD) encompasses chronic inflammatory conditions of the distal gastrointestinal tract, including Crohn's disease and ulcerative colitis. This chapter explores the potential of Dendritic cell-associated C-type lectin-1 (Dectin-1), a pattern recognition receptor, as a therapeutic target for IBD. We delve into the multifaceted roles of Dectin-1 in immune response modulation, focusing on its interactions with the gut microbiota and immune system. Key sections include an examination of intestinal dysbiosis and its impact on IBD, highlighting the critical role of fungal dysbiosis and immune responses mediated by Dectin-1. The chapter discusses the dual functions of Dectin-1 in maintaining gut homeostasis and its contribution to disease pathogenesis through interactions with the gut's fungal community. Furthermore, the genetic and molecular mechanisms underpinning Dectin-1's role in IBD susceptibility are explored, alongside its signaling pathways and their effects on immune modulation. We also present therapeutic strategies targeting Dectin-1, including innovative drug delivery systems that leverage its natural binding affinity for β-glucans, enhancing targeted delivery to inflamed tissues. The chapter underscores the potential of dietary modulation of Dectin-1 pathways to restore gut microbiota balance and suggests future research directions to fully exploit Dectin-1's therapeutic potential in managing IBD. By elucidating the complex interplay between Dectin-1 and the gut microbiota, this chapter provides insights into novel therapeutic approaches aimed at mitigating IBD symptoms and improving patient outcomes.

Insights into the intestinal microbiota of Exopalaemon annandalei and Exopalaemon carinicauda in the Yangtze River estuary

The gut microbiota plays a crucial role in food webs, carbon cycling, and related elements. Exopalaemon annandalei and Exopalaemon carinicauda are two important forage species in the Yangtze River estuary with extremely similar living habits and morphological characteristics. Exploring the microorganisms in the guts of these two shrimp species can help us understand the survival status of forage species and gut microbiota in the Yangtze River estuary. Therefore, this study analyzed the similarities and differences in the intestinal flora of E. annandalei and E. carinicauda through high-throughput sequencing of 16S rRNA gene amplicons. The results showed that the dominant bacteria in the intestinal flora of E. annandalei and E. carinicauda at the phylum level were Proteobacteria and Firmicutes, respectively. At the genus level, the intestinal flora had higher concentrations of Psychrobacter, Bacillus, Pseudomonas, Acinetobacter, and Macrococcus. In both shrimp species, the contents of Acinetobacter and Macrococcus were higher in spring than in winter. The most important potential functions of the intestinal microbiota were amino acid metabolism and purine metabolism. Additionally, the functions of metabolism and diseases in the intestinal microbiota of E. annandalei were greatly influenced by the season. Furthermore, the experimental results indicated that a lower ratio of Firmicutes to Bacteroidetes was associated with a larger body weight in shrimp. Overall, this study provides a theoretical reference for understanding the intestinal bacterial community of shrimp in estuaries and the healthy cultivation of E. annandalei and E. carinicauda.

Glycaemic sugar metabolism and the gut microbiota: past, present and future

Non-communicable diseases (NCDs), such as type 2 diabetes (T2D) and metabolic dysfunction-associated fatty liver disease, have reached epidemic proportions worldwide. The global increase in dietary sugar consumption, which is largely attributed to the production and widespread use of cheap alternatives such as high-fructose corn syrup, is a major driving factor of NCDs. Therefore, a comprehensive understanding of sugar metabolism and its impact on host health is imperative to rise to the challenge of reducing NCDs. Notably, fructose appears to exert more pronounced deleterious effects than glucose, as hepatic fructose metabolism induces de novo lipogenesis and insulin resistance through distinct mechanisms. Furthermore, recent studies have demonstrated an intricate relationship between sugar metabolism and the small intestinal microbiota (SIM). In contrast to the beneficial role of colonic microbiota in complex carbohydrate metabolism, sugar metabolism by the SIM appears to be less beneficial to the host as it can generate toxic metabolites. These fermentation products can serve as a substrate for fatty acid synthesis, imposing negative health effects on the host. Nevertheless, due to the challenging accessibility of the small intestine, our knowledge of the SIM and its involvement in sugar metabolism remains limited. This review presents an overview of the current knowledge in this field along with implications for future research, ultimately offering potential therapeutic avenues for addressing NCDs.

Gastrointestinal digestion of yerba mate, rosemary and green tea extracts and their subsequent colonic fermentation by human, pig or rat inocula

Polyphenolic compounds are common constituents of human and animal diets and undergo extensive metabolism by the gut microbiota before entering circulation. In order to compare the transformations of polyphenols from yerba mate, rosemary, and green tea extracts in the gastrointestinal tract, simulated gastrointestinal digestion coupled with colonic fermentation were used. For enhancing the comparative character of the investigation, colonic fermentation was performed with human, pig and rat intestinal microbiota. Chemical analysis was performed using a HPLC system coupled to a diode-array detector and mass spectrometer. Gastrointestinal digestion diminished the total amount of phenolics in the rosemary and green tea extracts by 27.5 and 59.2 %, respectively. These reductions occurred mainly at the expense of the major constituents of these extracts, namely rosmarinic acid (-45.7 %) and epigalocatechin gallate (-60.6 %). The yerba mate extract was practically not affected in terms of total phenolics, but several conversions and isomerizations occurred (e.g., 30 % of trans-3-O-caffeoylquinic acid was converted into the cis form). The polyphenolics of the yerba mate extract were also the least decomposed by the microbiota of all three species, especially in the case of the human one (-10.8 %). In contrast, the human microbiota transformed the polyphenolics of the rosemary and green extracts by 95.9 and 88.2 %, respectively. The yerba mate-extract had its contents in cis 3-O-caffeoylquinic acid diminished by 78 % by the human microbiota relative to the gastrointestinal digestion, but the content of 5-O-caffeoylquinic acid (also a chlorogenic acid), was increased by 22.2 %. The latter phenomenon did not occur with the rat and pig microbiota. The pronounced interspecies differences indicate the need for considerable caution when translating the results of experiments on the effects of polyphenolics performed in rats, or even pigs, to humans.

Understanding the Dynamics of Human Defensin Antimicrobial Peptides: Pathogen Resistance and Commensal Induction

Antimicrobial peptides (AMPs), also known as host defense peptides, are petite molecules with inherent microbicidal properties that are synthesized by the host's innate immune response. These peptides serve as an initial barrier against pathogenic microorganisms, effectively eliminating them. Human defensin (HD) AMPs represent a prominent group of peptides involved in the innate immune response of humans. These peptides are primarily produced by neutrophils and epithelial cells, serving as a crucial defense mechanism against invading pathogens. The extensive research conducted has focused on the broad spectrum of antimicrobial activities and multifaceted immunomodulatory functions exhibited by human defensin AMPs. During the process of co-evolution between hosts and bacterial pathogens, bacteria have developed the ability to recognize and develop an adaptive response to AMPs to counterattack their bactericidal activity by different antibiotic-resistant mechanisms. However, numerous non-pathogenic commensal bacteria elicit the upregulation of defensins as a means to surmount the resistance mechanisms implemented by pathogens. The precise mechanism underlying the induction of HD by commensal organisms remains to be fully understood. This review summarizes the most recent research on the expression of human defensin by pathogens and discusses the various defense mechanisms used by pathogens to counter host AMP production. We also mention recent developments in the commensal induction of defensin AMPs. A better knowledge of the pathogens' defensin AMP resistance mechanisms and commensals' induction of AMP expression may shed light on the creation of fresh antibacterial tactics to get rid of bacterial infection.

Characterization of the gastrointestinal microbiome of the Syrian hamster (Mesocricetus auratus) and comparison to data from mice

Syrian hamsters (Mesocricetus auratus) have been increasingly used as rodent models in recent years, especially for SARS-CoV-2 since the pandemic. However, the physiology of this animal model is not yet well-understood, even less when considering the digestive tract. Generally, the gastrointestinal microbiome influences the immune system, drug metabolism, and vaccination efficacy. However, a detailed understanding of the gastrointestinal microbiome of hamsters is missing. Therefore, we analyzed 10 healthy 11-week-old RjHan:AURA hamsters fed a pelleted standard diet. Their gastrointestinal content was sampled (i.e., forestomach, glandular stomach, ileum, cecum, and colon) and analyzed using 16S rRNA gene amplicon sequencing. Results displayed a distinct difference in the bacterial community before and after the cecum, possibly due to the available nutrients and digestive functions. Next, we compared hamsters with the literature data of young-adult C57BL/6J mice, another important animal model. We sampled the same gastrointestinal regions and analyzed the differences in the microbiome between both rodents. Surprisingly, we found strong differences in their specific gastrointestinal bacterial communities. For instance, Lactobacillaceae were more abundant in hamsters' forestomach and ileum, while Muribaculaceae dominated in the mouse forestomach and ileum. Similarly, in mouse cecum and colon, Muribaculaceae were dominant, while in hamsters, Lachnospiraceae and Erysipelotrichaceae dominated the bacterial community. Molecular strains of Muribaculaceae in both rodent species displayed some species specificity. This comparison allows a better understanding of the suitability of the Syrian hamster as an animal model, especially regarding its comparability to other rodent models. Thereby, this work contributes to the characterization of the hamster model and allows better experimental planning.

Interplay of poultry-microbiome interactions - influencing factors and microbes in poultry infections and metabolic disorders

1. The poultry microbiome and its stability at every point in time, either free range or reared under different farming systems, is affected by several environmental and innate factors. The interaction of the poultry birds with their microbiome, as well as several inherent and extraneous factors contribute to the microbiome dynamics. A poor understanding of this could worsen poultry heath and result in disease/metabolic disorders.2. Many diseased states associated with poultry have been linked to dysbiosis state, where the microbiome experiences some perturbation. Dysbiosis itself is too often downplayed; however, it is considered a disease which could lead to more serious conditions in poultry. The management of interconnected factors by conventional and emerging technologies (sequencing, nanotechnology, robotics, 3D mini-guts) could prove to be indispensable in ensuring poultry health and welfare.3. Findings showed that high-throughput technological advancements enhanced scientific insights into emerging trends surrounding the poultry gut microbiome and ecosystem, the dysbiotic condition, and the dynamic roles of intrinsic and exogenous factors in determining poultry health. Yet, a combination of conventional, -omics based and other techniques further enhance characterisation of key poultry microbiome actors, their mechanisms of action, and roles in maintaining gut homoeostasis and health, in a bid to avert metabolic disorders and infections.4. In conclusion, there is an important interplay of innate, environmental, abiotic and biotic factors impacting on poultry gut microbiome homoeostasis, dysbiosis, and overall health. Associated infections and metabolic disorders can result from the interconnected nature of these factors. Emerging concepts (interkingdom or network signalling and neurotransmitter), and future technologies (mini-gut models, cobots) need to include these interactions to ensure accurate control and outcomes.

The association of infant and mother gut microbiomes with development of allergic diseases in children: a systematic review

OBJECTIVE

It is believed that gut microbiota alteration leads to both intestinal and non-intestinal diseases in children. Since infants inherit maternal microbiota during pregnancy and lactation, recent studies suggest that changes in maternal microbiota can cause immune disorders as well. This systematic review was designed to assess the association between the child and mother's gut microbiome and allergy development in childhood.

DATA SOURCES

In this systematic review, international databases including PubMed, Scopus, and ISI/WOS were searched until January 2023 to identify relevant studies.

STUDY SELECTIONS

Observational studies that analyzed infant or maternal stool microbiome and their association with allergy development in children were included in this study. Data extraction and quality assessment of the included studies were independently conducted by two researchers.

RESULTS

Of the 1694 papers evaluated, 21 studies examined neonate gut microbiome by analyzing stool samples and six studies examined maternal gut microbiota. A total of 5319 participants were included in this study. Asthma followed by eczema and dermatitis were the most common allergy disorders among children. Urbanization caused a lack of diversity in the bacterial microbiota as well as lower levels of Bifidobacterium and Lachnospira associated with a higher risk of allergy. In contrast, higher levels of Roseburia and Flavonifractor were associated with lower allergy risk.

CONCLUSIONS

This systematic review shows that gut microbiota may be associated with allergy development. Further studies are required to provide a definitive answer.

Influenza and the gut microbiota: A hidden therapeutic link

Background

The extensive community of gut microbiota significantly influences various biological functions throughout the body, making its characterization a focal point in biomedicine research. Over the past few decades, studies have revealed a potential link between specific gut bacteria, their associated metabolic pathways, and influenza. Bacterial metabolites can communicate directly or indirectly with organs beyond the gut via the intestinal barrier, thereby impacting the physiological functions of the host. As the microbiota increasingly emerges as a 'gut signature' in influenza, gaining a deeper understanding of its role may offer new insights into its pathophysiological relevance and open avenues for novel therapeutic targets. In this Review, we explore the differences in gut microbiota between healthy individuals and those with influenza, the relationship between gut microbiota metabolites and influenza, and potential strategies for preventing and treating influenza through the regulation of gut microbiota and its metabolites, including fecal microbiota transplantation and microecological preparations.

Methods

We utilized PubMed and Web of Science as our search databases, employing keywords such as "influenza," "gut microbiota," "traditional Chinese medicine," "metabolites," "prebiotics," "probiotics," and "machine learning" to retrieve studies examining the potential therapeutic connections between the modulation of gut microbiota and its metabolites in the treatment of influenza. The search encompassed literature from the inception of the databases up to December 2023.

Results

Fecal microbiota transplantation (FMT), microbial preparations (probiotics and prebiotics), and traditional Chinese medicine have unique advantages in regulating intestinal microbiota and its metabolites to improve influenza outcomes. The primary mechanism involves increasing beneficial intestinal bacteria such as Bacteroidetes and Bifidobacterium while reducing harmful bacteria such as Proteobacteria. These interventions act directly or indirectly on metabolites such as short-chain fatty acids (SCFAs), amino acids (AAs), bile acids, and monoamines to alleviate lung inflammation, reduce viral load, and exert anti-influenza virus effects.

Conclusion

The gut microbiota and its metabolites have direct or indirect therapeutic effects on influenza, presenting broad research potential for providing new directions in influenza research and offering references for clinical prevention and treatment. Future research should focus on identifying key strains, specific metabolites, and immune regulation mechanisms within the gut microbiota to accurately target microbiota interventions and prevent respiratory viral infections such as influenza.

Role of Gut Microbial Metabolites in Cardiovascular Diseases-Current Insights and the Road Ahead

Cardiovascular diseases (CVDs) are the leading cause of premature morbidity and mortality globally. The identification of novel risk factors contributing to CVD onset and progression has enabled an improved understanding of CVD pathophysiology. In addition to the conventional risk factors like high blood pressure, diabetes, obesity and smoking, the role of gut microbiome and intestinal microbe-derived metabolites in maintaining cardiovascular health has gained recent attention in the field of CVD pathophysiology. The human gastrointestinal tract caters to a highly diverse spectrum of microbes recognized as the gut microbiota, which are central to several physiologically significant cascades such as metabolism, nutrient absorption, and energy balance. The manipulation of the gut microbial subtleties potentially contributes to CVD, inflammation, neurodegeneration, obesity, and diabetic onset. The existing paradigm of studies suggests that the disruption of the gut microbial dynamics contributes towards CVD incidence. However, the exact mechanistic understanding of such a correlation from a signaling perspective remains elusive. This review has focused upon an in-depth characterization of gut microbial metabolites and their role in varied pathophysiological conditions, and highlights the potential molecular and signaling mechanisms governing the gut microbial metabolites in CVDs. In addition, it summarizes the existing courses of therapy in modulating the gut microbiome and its metabolites, limitations and scientific gaps in our current understanding, as well as future directions of studies involving the modulation of the gut microbiome and its metabolites, which can be undertaken to develop CVD-associated treatment options. Clarity in the understanding of the molecular interaction(s) and associations governing the gut microbiome and CVD shall potentially enable the development of novel druggable targets to ameliorate CVD in the years to come.

Personalized identification of autism-related bacteria in the gut microbiome using explainable artificial intelligence

Autism spectrum disorder (ASD) affects social interaction and communication. Emerging evidence links ASD to gut microbiome alterations, suggesting that microbial composition may play a role in the disorder. This study employs explainable artificial intelligence (XAI) to examine the contributions of individual microbial species to ASD. By using local explanation embeddings and unsupervised clustering, the research identifies distinct ASD subgroups, underscoring the disorder's heterogeneity. Specific microbial biomarkers associated with ASD are revealed, and the best classifiers achieved an AU-ROC of 0.965 ± 0.005 and an AU-PRC of 0.967 ± 0.008. The findings support the notion that gut microbiome composition varies significantly among individuals with ASD. This work's broader significance lies in its potential to inform personalized interventions, enhancing precision in ASD management and classification. These insights highlight the importance of individualized microbiome profiles for developing tailored therapeutic strategies for ASD.

Advancements in gene editing technologies for probiotic-enabled disease therapy

Probiotics typically refer to microorganisms that have been identified for their health benefits, and they are added to foods or supplements to promote the health of the host. A growing number of probiotic strains have been identified lately and developed into valuable regulatory pharmaceuticals for nutritional and medical applications. Gene editing technologies play a crucial role in addressing the need for safe and therapeutic probiotics in disease treatment. These technologies offer valuable assistance in comprehending the underlying mechanisms of probiotic bioactivity and in the development of advanced probiotics. This review aims to offer a comprehensive overview of gene editing technologies applied in the engineering of both traditional and next-generation probiotics. It further explores the potential for on-demand production of customized products derived from enhanced probiotics, with a particular emphasis on the future of gene editing in the development of live biotherapeutics.

Roundup-Induced Gut Dysbiosis, Irrelevant to Aromatic Amino Acid Deficiency, Impairs the Gut Function in Rats

Glyphosate, the most popular herbicide globally, has long been considered safe for mammals. However, whether glyphosate can disturb gut microbiota via inhibiting aromatic amino acid (AAA) synthesis has been under debate recently. Here, we evaluated the impacts of chronic exposure to Roundup on gut health with the addition of AAA and explored the mechanism behind Roundup-induced gut dysfunction by performing fecal microbiota transplantation. 500 mg/kg·bw of Roundup, independent of AAA deficiency, caused severe damage to gut function, as characterized by gut microbial dysbiosis, oxidative stress damage, intestinal inflammation, and histopathological injury, particularly in female rats. Notably, similar to Roundup, Roundup-shaped gut microbiome evidently damaged serum, cecum, and colon profiling of oxidative stress biomarkers (malonaldehyde (MDA), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), glutathione (GSH), and H2O2). Moreover, it induced 0.65-, 3.29-, and 2.36-fold increases in colonic IL-1β, IL-6, and TNF-α levels, and 0.34-fold decreases in the IL-10 level. Upon transplanting healthy fecal microbiota to Roundup-treated rats, they exhibited a healthier gut microenvironment with mitigated inflammation, oxidative damage, and intestinal injury. Overall, our findings provide new insights into the safety of Roundup, highlight the crucial role of gut microbiota in Roundup-induced gut dysfunction, and pave the way for developing gut-microbiota-based strategies to address Roundup-related safety issues.