Colonic bacterial metabolites and human health. Curr Opin Microbiol. 2013;16:246-254. [PMID: 23880135 DOI: 10.1016/j.mib.2013.07.002]

The attenuation of gut microbiota-derived short-chain fatty acids elevates lipid transportation through suppression of the intestinal HDAC3-H3K27ac-PPAR-γ axis in gestational diabetes mellitus

Gut flora is considered to modulate lipid transport from the intestine into the bloodstream, and thus may potentially participate in the development of GDM. Although previous studies have shown that the intestinal microbiota influences lipid transport and metabolism in GDM, the precise mechanisms remain elusive. To address this, we used a high-fat diet (HFD)-induced GDM mouse model and conducted 16s rRNA sequencing and fecal metabolomics to assess gut microbial community shifts and associated metabolite changes. Western blot, ELISA, and chromatin immunoprecipitation (ChIP) were utilized to elucidate how gut microbiota affect intestinal lipid transport and the insulin sensitivity of hepatic, adipose, and skeletal muscle tissues. We found that HFD impaired the oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) in pregnant mice. 16s rRNA sequencing demonstrated profound compositional changes, especially in the relative abundances of Firmicutes and Bacteroidetes. Metabolomics analysis presented a decline in the concentration of short-chain fatty acids (SCFAs) in the GDM group. Western blot analyses showed an upregulation of HDAC3 and a concurrent reduction in H3K27 acetylation in the intestine. ChIP-qPCR showed that PPAR-γ was inhibited, which in turn activated lipid-transporter CD36. ELISA and insulin signaling pathway detection in insulin-target organs showed high concentrations of circulating fatty acids and triglycerides and insulin resistance in insulin-target organs. Our results suggest that gut microbiota is closely associated with the development of GDM, partly because decreased gut flora-associated SCFAs activate CD36 by suppressing the HDAC3-H3K27ac-PPAR-γ axis to transport excessive fatty acids and triglycerides into blood circulation, thereby dysregulating the insulin sensitivity of insulin target organs.

Anemarrhena asphodeloides Bunge polysaccharides alleviate lipoteichoic acid-induced lung inflammation and modulate gut microbiota in mice

Pneumonia remains a prevalent infection primary ailment characterized by severe lung inflammation, leading to respiratory distress and significant mortality rates, particularly affecting young children in less developed regions. This study explores the therapeutic potential of low and high-molecular weight polysaccharides derived from Anemarrhena asphodeloides in a murine model of lipoteichoic acid (LTA)-induced pneumonia, which represents bacterial-induced lung inflammation. Administration of Anemarrhena asphodeloides polysaccharides effectively alleviated LTA-induced symptoms, including decreased lung and colon inflammation, and restored dysbiosis of gut microbiota. Polysaccharide treatment notably increased mucin-2 expression, reduced serum cytokine levels (IL-10, TNF-α), and increased tight junction protein production (ZO-1, Occludin, Claudin). Additionally, polysaccharides promoted a significant recovery in gut microbiota composition, indicating potential prebiotic effects. These findings highlight the therapeutic capability of Anemarrhena asphodeloides polysaccharides against LTA-induced pneumonia through gut microbiota modulation and restored intestinal homeostasis.

Microbiota and beneficial metabolites in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related death worldwide. In recent years, the impact of the gut microbiota on the development of CRC has become clear. The gut microbiota is the community of microorganisms living in the gut symbiotic relationship with the host. These microorganisms contribute to the development of CRC through various mechanisms that are not yet fully understood. Increasing scientific evidence suggests that metabolites produced by the gut microbiota may influence CRC development by exerting protective and deleterious effects. This article reviews the metabolites produced by the gut microbiota, which are derived from the intake of complex carbohydrates, proteins, dairy products, and phytochemicals from plant foods and are associated with a reduced risk of CRC. These metabolites include short-chain fatty acids (SCFAs), indole and its derivatives, conjugated linoleic acid (CLA) and polyphenols. Each metabolite, its association with CRC risk, the possible mechanisms by which they exert anti-tumour functions and their relationship with the gut microbiota are described. In addition, other gut microbiota-derived metabolites that are gaining importance for their role as CRC suppressors are included.

Urinary metabolic profile and its predictive indexes after MSG consumption in rat

Monosodium glutamate (MSG) is a widely used food additive with conflicting evidence regarding its potential effects on human health, with proposed relevance for obesity and metabolic syndrome (MetS) or chronic kidney disease. As being able to accurately quantify the MSG dietary intake would help clarify the open issues, we constructed a predictive formula to estimate the daily intake of MSG in a rat model based on the urinary metabolic profile. Adult male Wistar rats were divided into groups receiving different daily amounts of MSG in drinking water (0.5, 1.5, and 3.0 g%), no MSG, and MSG withdrawal after 3.0% MSG treatment for 4 weeks. We then analyzed 24-hour urine samples for chemistries and metabolites using 1H NMR spectrometry and observed a strong correlation between urine pH, sodium, bicarbonate, alpha-ketoglutarate, citrate, fumarate, glutamate, methylamine, N-methyl-4-pyridone-3-carboxamide, succinate, and taurine and the daily MSG intake. Following the multiple linear regression analysis a simple formula model based on urinary Na+, citrate, and glutamate was most accurate and could be validated for estimating daily MSG intake. In conclusion, we propose that the daily MSG intake correlates with urinary metabolites in a rat model and that this new tool for monitoring the impact of MSG on health measures.

Antitumor properties of traditional lactic acid bacteria: Short-chain fatty acid production and interleukin 12 induction

This paper presents an in vitro evaluation of antitumor properties through producing short-chain fatty acids and inducing interleukin 12. In addition, it offers the most important and functional probiotic properties of 24 Lactobacillus gasseri, Lactiplantibacillus plantarum, Lactobacillus acidophilus, and Limosilactobacillus fermentum strains isolated from humans, foods, and fermented foods. To this end, survival in an acidic environment (pH = 2.5), tolerance in bile salt, viability in the presence of pepsin-pancreatin, adhesion percentage, antibiotic resistance, auto-aggregation, and potential percentage of co-aggregation are studied in contact with three human intestinal pathogens. These pathogens are Escherichia coli O157: H7 NCTC 12900, Salmonella enterica subsp. enterica ATCC 13076, and Listeria monocytogenes ATTC 7644. Also, in vitro induction amount of IL-12 in mouse splenocytes is investigated to evaluate antitumor properties by 19 strains of L. gasseri and L. plantarum along with the development of short-chain fatty acids (SCFA) by 5 strains of L. fermentum and L. acidophilus. Gas Chromatography Flame Ionization Detector (GC-FID) and enzyme-linked immunosorbent assay (ELISA) were used to measure short-chain fatty acids and IL-12, respectively. All strains had high viability under acidic conditions. The highest levels of pancreatin and pepsin resistance were found in strains LF56, LF57, LF55, OF, and F and strains LF56, LF57, and A7, respectively. All strains except LF56 had high resistance to bile salts. L. gasseri 54C had the highest average adhesion score (hydrophobicity) of 62.9 % among 19 strains. Despite the susceptibility of different strains of L. plantarum to the tested antibiotics, M8 and M11, S2G, A7, LF55, LF57, and 5G were resistant to kanamycin and chloramphenicol, respectively. Also, 21G was resistant to ampicillin, LF56 to tetracycline and M8, and M11, LF56, and 21G to Erythromycin. In addition, L. gasseri showed moderate resistance to ampicillin, erythromycin, and tetracycline, while L. fermentum ATCC 9338 showed good resistance to ampicillin, erythromycin, and chloramphenicol. In this respect, L. plantarum LF56 and gasseri 54C had the highest average auto-aggregation and co-aggregation against three pathogenic bacteria, respectively. The highest and lowest levels of acetic acid as short-chain fatty acids were produced by L. fermentum 19SH isolated from Horre 41.62 and L. fermentum 21SH from fermented seeds 27.047, respectively. Moreover, L. fermentum, with the OF code of traditional-fermented food origin, produced the most isobutyric acid, butyric acid, and valeric acid, with values of 0.6828, 0.74165, and 0.49915 mmol, respectively. L. fermentum isolated from the human origin with code F produced the most isovaleric acid of 1.1874 mmol. All the tested strains produced good propionic acid except L. fermentum 21SH from fermented seeds. Among strains, L. plantarum M11 isolated from milk and L. gasseri 52B from humans had the highest in vitro induction of IL-12, which is probably related to their cell wall compositions and structure.

In Vitro Fermentation of Animal and Plant Protein Isolates by the Human Gut Microbiota Under High and Low Carbohydrate Conditions

SCOPE

There is a lack of research comparing how different protein isolates influence the microbiome, especially when carbohydrate (CHO) availability is varied. The objective is to determine changes in gut microbiota composition and function during fermentation of digested protein isolates under high and low CHO conditions.

METHODS AND RESULTS

Protein isolates from beef, egg white, milk, pea, and soy are subjected to in vitro digestion and fermentation with human fecal microbiota. Under low CHO conditions, the microbiota is primarily proteolytic with decreased concentrations of peptides and increased variance among microbial taxa and production of ammonia and branched chain fatty acids by the microbiota. Milk protein not only results in the highest production of butyrate and p-hydroxyphenylacetate but also has high concentrations of deleterious fermentation metabolites. Amino acid composition of the protein isolates is significantly correlated with abundances of many microbial taxa and metabolites, but the correlations are stronger in the low CHO medium.

CONCLUSION

This study shows that low CHO conditions increase proteolytic fermentation and result in increased differences in microbiota response to protein isolates. It also showed that amino acid composition is highly associated with microbiota composition and function especially under low CHO conditions.

Impact of Simulated Human Gastrointestinal Digestion on the Functional Properties of Dietary Fibres Obtained from Broccoli Leaves, Grape Stems, Pomegranate and Tomato Peels

This study aimed to analyse the impact of a simulated human digestion process on the composition and functional properties of dietary fibres derived from pomegranate-peel, tomato-peel, broccoli-stem and grape-stem by-products. For this purpose, a computer-controlled simulated digestion system consisting of three bioreactors (simulating the stomach, small intestine and colon) was utilised. Non-extractable phenols associated with dietary fibre and their influence on antioxidant capacity and antiproliferative activity were investigated throughout the simulated digestive phases. Additionally, the modifications in oligosaccharide composition, the microbiological population and short-chain fatty acids produced within the digestion media were examined. The type and composition of each dietary fibre significantly influenced its functional properties and behaviour during intestinal transit. Notably, the dietary fibre from the pomegranate peel retained its high phenol content throughout colon digestion, potentially enhancing intestinal health due to its strong antioxidant activity. Similarly, the dietary fibre from broccoli stems and pomegranate peel demonstrated anti-proliferative effects in both the small and the large intestines, prompting significant modifications in colonic microbiology. Moreover, these fibre types promoted the growth of bifidobacteria over lactic acid bacteria. Thus, these results suggest that the dietary fibre from pomegranate peel seems to be a promising functional food ingredient for improving human health.

Mangaba pulp fermented with Lacticaseibacillus casei 01 has improved chemical, technological, and sensory properties and positively impacts the colonic microbiota of vegan adults

This study aimed to evaluate the functional, technological, and sensory aspects of mangaba (Hancornia speciosa Gomes) fruit pulp fermented with the probiotic Lacticaseibacillus casei 01 (LC1) during refrigerated storage (7 °C, 28 days). The effects of the fermented mangaba pulp on the modulation of the intestinal microbiota of healthy vegan adults were also assessed. Mangaba pulp allowed high viability of LC1 during storage and after simulated gastrointestinal conditions (≥7 log CFU/g). The fermented mangaba pulp showed lower pH and total soluble solids, and higher titratable acidity, and concentrations of lactic, acetic, citric, and propionic acids during storage compared to non-fermented pulp. Also, it presented a higher concentration of bioaccessible phenolics and volatiles, and improved sensory properties (yellow color, brightness, fresh appearance, and typical aroma and flavor). Fermented mangaba pulp added to in vitro cultured colonic microbiota of vegan adults decreased the pH values and concentrations of maltose, glucose, and citric acid while increasing rhamnose and phenolic contents. Fermented mangaba pulp promoted increases in the abundance of Dorea, Romboutsia, Faecalibacterium, Lachnospira, and Lachnospiraceae ND3007 genera and positively impacted the microbial diversity. Findings indicate that mangaba pulp fermented with LC1 has improved chemical composition and functionality, inducing changes in the colonic microbiota of vegan adults associated with potential benefits for human health.

Applications of Strain-Specific Probiotics in the Management of Cardiovascular Diseases: A Systemic Review

Cardiovascular diseases (CVDs) are a leading cause of global mortality and novel approaches for prevention and management are needed. The human gastrointestinal tract hosts a diverse microbiota that is crucial in maintaining metabolic homeostasis. The formulation of effective probiotics, alone or in combination, has been under discussion due to their impact on cardiovascular and metabolic diseases. Probiotics have been shown to impact cardiovascular health positively. An imbalance in the presence of Firmicutes and Bacteroidetes has been linked to the progression of CVDs due to their impact on bile acid and cholesterol metabolism. The probiotics primarily help in the reduction of plasma low-density lipoprotein levels and attenuation of the proinflammatory markers. These beneficial microorganisms contribute to lowering cholesterol levels and produce essential short-chain fatty acids. The impact of lipid-regulating probiotic strains on human health is quite significant. However, only a few have been tested for potential beneficial efficacy, and ambiguity exists regarding strain dosages, interactions with confounding factors, and potential adverse effects. Hence, more comprehensive studies and randomized trials are needed to understand the mechanisms of probiotics on CVDs and to ensure human health. This review assesses the evidence and highlights the roles of strain-specific probiotics in the management of CVDs.

The role of microbial metabolites in endocrine tumorigenesis: From the mechanistic insights to potential therapeutic biomarkers

Microbial metabolites have been indicated to communicate with the host's endocrine system, regulating hormone production, immune-endocrine communications, and interactions along the gut-brain axis, eventually affecting the occurrence of endocrine cancer. Furthermore, microbiota metabolites such as short-chain fatty acids (SCFAs) have been found to affect the tumor microenvironment and boost immunity against tumors. SCFAs, including butyrate and acetate, have been demonstrated to exert anti-proliferative and anti-protective activity on pancreatic cancer cells. The employing of microbial metabolic products in conjunction with radiation and chemotherapy has shown promising outcomes in terms of reducing treatment side effects and boosting effectiveness. Certain metabolites, such as valerate and butyrate, have been made known to improve the efficiency of CAR T-cell treatment, whilst others, such as indole-derived tryptophan metabolites, have been shown to inhibit tumor immunity. This review explores the intricate interplay between microbial metabolites and endocrine tumorigenesis, spanning mechanistic insights to the discovery of potential therapeutic biomarkers.

Gut microbiota dynamics and fecal SCFAs after colonoscopy: accelerating microbiome stabilization by Clostridium butyricum

BACKGROUND

Colonoscopy is a classic diagnostic method with possible complications including abdominal pain and diarrhoea. In this study, gut microbiota dynamics and related metabolic products during and after colonoscopy were explored to accelerate gut microbiome balance through probiotics.

METHODS

The gut microbiota and fecal short-chain fatty acids (SCFAs) were analyzed in four healthy subjects before and after colonoscopy, along with seven individuals supplemented with Clostridium butyricum. We employed 16S rRNA sequencing and GC-MS to investigate these changes. We also conducted bioinformatic analysis to explore the buk gene, encoding butyrate kinase, across C. butyricum strains from the human gut.

RESULTS

The gut microbiota and fecal short-chain fatty acids (SCFAs) of four healthy subjects were recovered on the 7th day after colonoscopy. We found that Clostridium and other bacteria might have efficient butyric acid production through bioinformatic analysis of the buk and assessment of the transcriptional level of the buk. Supplementation of seven healthy subjects with Clostridium butyricum after colonoscopy resulted in a quicker recovery and stabilization of gut microbiota and fecal SCFAs on the third day.

CONCLUSION

We suggest that supplementation of Clostridium butyricum after colonoscopy should be considered in future routine clinical practice.

Exploring the interplay between running exercises, microbial diversity, and tryptophan metabolism along the microbiota-gut-brain axis

The emergent recognition of the gut-brain axis connection has shed light on the role of the microbiota in modulating the gut-brain axis's functions. Several microbial metabolites, such as serotonin, kynurenine, tryptamine, indole, and their derivatives originating from tryptophan metabolism have been implicated in influencing this axis. In our study, we aimed to investigate the impact of running exercises on microbial tryptophan metabolism using a mouse model. We conducted a multi-omics analysis to obtain a comprehensive insight into the changes in tryptophan metabolism along the microbiota-gut-brain axis induced by running exercises. The analyses integrated multiple components, such as tryptophan changes and metabolite levels in the gut, blood, hippocampus, and brainstem. Fecal microbiota analysis aimed to examine the composition and diversity of the gut microbiota, and taxon-function analysis explored the associations between specific microbial taxa and functional activities in tryptophan metabolism. Our findings revealed significant alterations in tryptophan metabolism across multiple sites, including the gut, blood, hippocampus, and brainstem. The outcomes indicate a shift in microbiota diversity and tryptophan metabolizing capabilities within the running group, linked to increased tryptophan transportation to the hippocampus and brainstem through circulation. Moreover, the symbiotic association between Romboutsia and A. muciniphila indicated their potential contribution to modifying the gut microenvironment and influencing tryptophan transport to the hippocampus and brainstem. These findings have potential applications for developing microbiota-based approaches in the context of exercise for neurological diseases, especially on mental health and overall well-being.

The relationship between the gut microbiome and resistance training: a rapid review

The human gut microbiome is attracting increasing attention because of its overall effect on health. Several reviews have investigated the impact of physical activity on the gut microbiome; however, these predominantly concentrate on either endurance or a combination of physical activities. This study aims to describe the effect of resistance or strength training on the gut microbiome of a human population. This rapid review follows the guidelines of the Cochrane Rapid Reviews Guidance along with PRISMA. A review of the literature was carried out using articles indexed by PubMed, Scopus, and Web of Science published in the last 12 years. None of the seven studies included find significant change in the gut microbiome in terms of bacterial taxa composition or overall diversity, though the results show that resistance training might decrease the zonulin level and increase mucin production and thereby reduce inflammation in the gut. Interestingly, two studies point to a gut-muscle axis connection and this is discussed in our paper. However, due to the small number of existing studies and certain methodological disagreements, it was hard to find a consensus on the relationship between the gut microbiome and resistance training.

Dysbiosis and Alzheimer's disease: role of probiotics, prebiotics and synbiotics

Alzheimer's disease (AD) is a neurodegenerative disease characterized by dementia and the accumulation of amyloid beta in the brain. Recently, microbial dysbiosis has been identified as one of the major factors involved in the onset and progression of AD. Imbalance in gut microbiota is known to affect central nervous system (CNS) functions through the gut-brain axis and involves inflammatory, immune, neuroendocrine and metabolic pathways. An altered gut microbiome is known to affect the gut and BBB permeability, resulting in imbalance in levels of neurotransmitters and neuroactive peptides/factors. Restoration of levels of beneficial microorganisms in the gut has demonstrated promising effects in AD in pre-clinical and clinical studies. The current review enlists the important beneficial microbial species present in the gut, the effect of their metabolites on CNS, mechanisms involved in dysbiosis related to AD and the beneficial effects of probiotics on AD. It also highlights challenges involved in large-scale manufacturing and quality control of probiotic formulations.

Butyrogenic, bifidogenic and slight anti-inflammatory effects of a green kiwifruit powder (Kiwi FFG®) in a human gastrointestinal model simulating mild constipation

Green kiwi (Actinidia deliciosa var. Hayward) is a fruit with important nutritional attributes and traditional use as a laxative. In this work, we studied in vitro the colonic fermentation of a standardized green kiwifruit powder (Kiwi FFG®) using representative intestinal microbial content of mildly constipated women. Static (batch) and dynamic configurations of the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) were used to estimate the impact of Kiwi FFG® in the human gut. Analysis of metabolites revealed a significant butyrogenic effect of the kiwifruit powder and, consistently, butyrate-producing bacterial populations (i.e., Faecalibacterium prausnitzii, Cluster IV, Roseburia spp.) were greatly increased in the dynamic gastrointestinal model. Bifidobacterium spp. was also found boosted in the microflora of ascending and transverse colon sections, and a significant rise of Akkermansia muciniphila was identified in the transverse colon. Reporter gene assays using human intestinal cells (HT-29) showed that kiwifruit fermentation metabolites activate the aryl hydrocarbon receptor (AhR) transcriptional pathway, which is an important regulator of intestinal homeostasis and immunity. Moreover, modulation in the production of human interleukins (IL-6 and IL-10) in Caco-2 cells suggested a potential mild anti-inflammatory effect of the kiwifruit powder and its gut microbiota-derived metabolites. Our results suggested a potential health benefit of Kiwi FFG® in the gut microbiota, particularly in the context of constipated people.

Understanding the potential causes of gastrointestinal dysfunctions in multiple system atrophy

Multiple system atrophy (MSA) is a rare, progressive neurodegenerative disorder characterised by autonomic, pyramidal, parkinsonian and/or cerebellar dysfunction. Autonomic symptoms of MSA include deficits associated with the gastrointestinal (GI) system, such as difficulty swallowing, abdominal pain and bloating, nausea, delayed gastric emptying, and constipation. To date, studies assessing GI dysfunctions in MSA have primarily focused on alterations of the gut microbiome, however growing evidence indicates other structural components of the GI tract, such as the enteric nervous system, the intestinal barrier, GI hormones, and the GI-driven immune response may contribute to MSA-related GI symptoms. Here, we provide an in-depth exploration of the physiological, structural, and immunological changes theorised to underpin GI dysfunction in MSA patients and highlight areas for future research in order to identify more suitable pharmaceutical treatments for GI symptoms in patients with MSA.

Genome-wide Mendelian randomization identifies putatively causal gut microbiota for multiple peptic ulcer diseases

Objective

The pathogenesis of peptic ulcer diseases (PUDs) involves multiple factors, and the contribution of gut microbiota to this process remains unclear. While previous studies have associated gut microbiota with peptic ulcers, the precise nature of the relationship, whether causal or influenced by biases, requires further elucidation.

Design

The largest meta-analysis of genome-wide association studies was conducted by the MiBioGen consortium, which provided the summary statistics of gut microbiota for implementation in the Mendelian randomization (MR) analysis. Summary statistics for five types of PUDs were compiled using the FinnGen Consortium R8 release data. Various statistical techniques, including inverse variance weighting (IVW), MR-Egger, weighted median (WM), weighted mode, and simple mode, were employed to assess the causal relationships between gut microbiota and these five PUDs.

Result

In the intestinal microbiome of 119 known genera, we found a total of 14 causal associations with various locations of PUDs and reported the potential pathogenic bacteria of Bilophila et al. Among them, four had causal relationships with esophageal ulcer, one with gastric ulcer, three with gastroduodenal ulcer, four with duodenal ulcer, and two with gastrojejunal ulcer.

Conclusion

In this study, the pathogenic bacterial genera in the gut microbiota that promote the occurrence of PUDs were found to be causally related. There are multiple correlations between intestinal flora and PUDs, overlapping PUDs have overlapping associated genera. The variance in ulcer-related bacterial genera across different locations underscores the potential influence of anatomical locations and physiological functions.

Mechanisms of Lung and Intestinal Microbiota and Innate Immune Changes Caused by Pathogenic Enterococcus Faecalis Promoting the Development of Pediatric Pneumonia

Bacterial pneumonia is the main cause of illness and death in children under 5 years old. We isolated and cultured pathogenic bacteria LE from the intestines of children with pneumonia and replicated the pediatric pneumonia model using an oral gavage bacterial animal model. Interestingly, based on 16srRNA sequencing, we found that the gut and lung microbiota showed the same imbalance trend, which weakened the natural resistance of this area. Further exploration of its mechanism revealed that the disruption of the intestinal mechanical barrier led to the activation of inflammatory factors IL-6 and IL-17, which promoted the recruitment of ILC-3 and the release of IL-17 and IL-22, leading to lung inflammation. The focus of this study is on the premise that the gut and lung microbiota exhibit similar destructive changes, mediating the innate immune response to promote the occurrence of pneumonia and providing a basis for the development and treatment of new drugs for pediatric pneumonia.

Supplementation of microencapsulated probiotics modulates gut health and intestinal microbiota

The beneficial effect of probiotics on host health is impaired due to the substantial loss of survivability during gastric transit caused by small intestinal enzymes and bile acids. Encapsulation helps to preserve the probiotics species from severe environmental factors. Lactobacillus paracasei, highly sensitive probiotic species to gastric acid, was encapsulated with polyacrylate resin. C57BL/6 male mice were equally divided into three groups; control group was fed with basal diet without any additives, the un-encapsulated group was fed with 0.1% of a mixture of encapsulating material and L. paracasei, and encapsulated group was fed with 0.1% encapsulated L. paracasei (microcapsule) for 4 weeks. The result showed elevated fecal moisture percentage in the encapsulated group, but not in the un-encapsulated group. Further study showed that the ratio of villus height to crypt depth in the small intestine was significantly higher compared to un-encapsulated and the control group. Microencapsulated probiotics also remarkably increased intestinal mucin and secretory immunoglobulin A (sIgA) concentration, intestinal MUC-2, and tight junction protein mRNA expression levels improving the intestinal barrier function of mice. In addition, microcapsules also reduced proinflammatory factor mRNA expression, while considerably increasing anti-inflammatory factor mRNA expression. Microbiota metabolites, fecal LPS (Lipopolysaccharide) were downregulated, and acetate and lactate were upraised compared to control. Furthermore, glutathione peroxidase (GSH-Px) and TAOC levels were increased and Malondialdehyde (MDA) was decreased improving antioxidant capacity. Microflora and bioinformatic predictive analysis of feces showed that encapsulated probiotics remarkably increased Lactobacillus proportions. Mice's intestinal health can thus be improved by using microencapsulated probiotics.

Role of the Gut Microbiota and Its Metabolites in Tumorigenesis or Development of Colorectal Cancer

Colorectal cancer (CRC) is the most common cancer of the digestive system with high mortality and morbidity rates. Gut microbiota is found in the intestines, especially the colorectum, and has structured crosstalk interactions with the host that affect several physiological processes. The gut microbiota include CRC-promoting bacterial species, such as Fusobacterium nucleatum, Escherichia coli, and Bacteroides fragilis, and CRC-protecting bacterial species, such as Clostridium butyricum, Streptococcus thermophilus, and Lacticaseibacillus paracasei, which along with other microorganisms, such as viruses and fungi, play critical roles in the development of CRC. Different bacterial features are identified in patients with early-onset CRC, combined with different patterns between fecal and intratumoral microbiota. The gut microbiota may be beneficial in the diagnosis and treatment of CRC; some bacteria may serve as biomarkers while others as regulators of chemotherapy and immunotherapy. Furthermore, metabolites produced by the gut microbiota play essential roles in the crosstalk with CRC cells. Harmful metabolites include some primary bile acids and short-chain fatty acids, whereas others, including ursodeoxycholic acid and butyrate, are beneficial and impede tumor development and progression. This review focuses on the gut microbiota and its metabolites, and their potential roles in the development, diagnosis, and treatment of CRC.

Talk to Me-Interplay between Mitochondria and Microbiota in Aging

The existence of mitochondria in eukaryotic host cells as a remnant of former microbial organisms has been widely accepted, as has their fundamental role in several diseases and physiological aging. In recent years, it has become clear that the health, aging, and life span of multicellular hosts are also highly dependent on the still-residing microbiota, e.g., those within the intestinal system. Due to the common evolutionary origin of mitochondria and these microbial commensals, it is intriguing to investigate if there might be a crosstalk based on preserved common properties. In the light of rising knowledge on the gut-brain axis, such crosstalk might severely affect brain homeostasis in aging, as neuronal tissue has a high energy demand and low tolerance for according functional decline. In this review, we summarize what is known about the impact of both mitochondria and the microbiome on the host's aging process and what is known about the aging of both entities. For a long time, bacteria were assumed to be immortal; however, recent evidence indicates their aging and similar observations have been made for mitochondria. Finally, we present pathways by which mitochondria are affected by microbiota and give information about therapeutic anti-aging approaches that are based on current knowledge.

Impact of the gut microbiota on angiotensin Ⅱ-related disorders and its mechanisms

The renin-angiotensin system (RAS) consists of multiple angiotensin peptides and performs various biological functions mediated by distinct receptors. Angiotensin II (Ang II) is the major effector of the RAS and affects the occurrence and development of inflammation, diabetes mellitus and its complications, hypertension, and end-organ damage via the Ang II type 1 receptor. Recently, considerable interest has been given to the association and interaction between the gut microbiota and host. Increasing evidence suggests that the gut microbiota may contribute to cardiovascular diseases, obesity, type 2 diabetes mellitus, chronic inflammatory diseases, and chronic kidney disease. Recent data have confirmed that Ang II can induce an imbalance in the intestinal flora and further aggravate disease progression. Furthermore, angiotensin converting enzyme 2 is another player in RAS, alleviates the deleterious effects of Ang II, modulates gut microbial dysbiosis, local and systemic immune responses associated with coronavirus disease 19. Due to the complicated etiology of pathologies, the precise mechanisms that link disease processes with specific characteristics of the gut microbiota remain obscure. This review aims to highlight the complex interactions between the gut microbiota and its metabolites in Ang II-related disease progression, and summarize the possible mechanisms. Deciphering these mechanisms will provide a theoretical basis for novel therapeutic strategies for disease prevention and treatment. Finally, we discuss therapies targeting the gut microbiota to treat Ang II-related disorders.

A pilot study of dietary fibres on pathogen growth in an ex vivo colonic model reveals their potential ability to limit vancomycin-resistant Enterococcus expansion

Aim: Dietary fibre is important for shaping gut microbiota. The aim of this pilot study was to investigate the impact of dietary fibres on pathogen performance in the presence of gut microbiota. Methods: In an ex vivo gut model, pooled faecal samples were spiked with a cocktail of representative gastrointestinal pathogens and fermented with yeast β-glucan for 24 hours, after which 16S rRNA amplicon sequencing and short-chain and branched-chain fatty acid (SCFA and BCFA) analyses were performed. In addition, oat β-glucan, arabinoxylan, yeast β-glucan, and galactooligosaccharides were each tested against individual representative pathogens and pathogen growth was assessed via qPCR. Glucose served as a control carbon source. Results: Based on 16S rRNA amplicon sequencing, yeast β-glucan selected for higher proportions of Bacteroides (P = 0.0005, ~6 fold) and Clostridia (P = 0.005, ~3.6 fold) while species of Escherichia/Shigella (P = 0.021, ~2.8 fold) and Lactobacillus (P = 0.007, ~ 15.7-fold) were higher in glucose. Pathogen relative abundance did not differ between glucose and yeast β-glucan. In the absence of pathogens, higher production of BCFAs (P = 0.002) and SCFAs (P = 0.002) fatty acids was observed for fibre group(s). For individual pathogens, yeast β-glucan increased growth of Escherichia coli, Salmonella typhimurium, and Listeria monocytogenes (P < 0.05), arabinoxylan increased S. typhimurium (P < 0.05). Tested fibres decreased vancomycin-resistant Enterococcus faecium (P < 0.05), with yeast β-glucan causing a 1-log reduction (P < 0.01), while galactooligosaccharides decreased L. monocytogenes (P < 0.05). Conclusion: Tested fibres differentially influenced the growth of pathogens, but yeast β-glucan could represent a dietary strategy to help limit vancomycin-resistant enterococci (VRE) expansion in the gut.

Challenges and strategies for preventing intestinal damage associated to mercury dietary exposure

Food represents the major risk factor for exposure to mercury in most human populations. Therefore, passage through the gastrointestinal tract plays a fundamental role in its entry into the organism. Despite the intense research carried out on the toxicity of Hg, the effects at the intestinal level have received increased attention only recently. In this review we first provide a critical appraisal of the recent advances on the toxic effects of Hg at the intestinal epithelium. Next, dietary strategies aimed to diminish Hg bioavailability or modulate the epithelial and microbiota responses will be revised. Food components and additives, including probiotics, will be considered. Finally, limitations of current approaches to tackle this problem and future lines of research will be discussed.

Protein posttranslational modifications in health and diseases: Functions, regulatory mechanisms, and therapeutic implications

Protein posttranslational modifications (PTMs) refer to the breaking or generation of covalent bonds on the backbones or amino acid side chains of proteins and expand the diversity of proteins, which provides the basis for the emergence of organismal complexity. To date, more than 650 types of protein modifications, such as the most well-known phosphorylation, ubiquitination, glycosylation, methylation, SUMOylation, short-chain and long-chain acylation modifications, redox modifications, and irreversible modifications, have been described, and the inventory is still increasing. By changing the protein conformation, localization, activity, stability, charges, and interactions with other biomolecules, PTMs ultimately alter the phenotypes and biological processes of cells. The homeostasis of protein modifications is important to human health. Abnormal PTMs may cause changes in protein properties and loss of protein functions, which are closely related to the occurrence and development of various diseases. In this review, we systematically introduce the characteristics, regulatory mechanisms, and functions of various PTMs in health and diseases. In addition, the therapeutic prospects in various diseases by targeting PTMs and associated regulatory enzymes are also summarized. This work will deepen the understanding of protein modifications in health and diseases and promote the discovery of diagnostic and prognostic markers and drug targets for diseases.

Gut Microbiome-Brain Alliance: A Landscape View into Mental and Gastrointestinal Health and Disorders

Gut microbiota includes a vast collection of microorganisms residing within the gastrointestinal tract. It is broadly recognized that the gut and brain are in constant bidirectional communication, of which gut microbiota and its metabolic production are a major component, and form the so-called gut microbiome-brain axis. Disturbances of microbiota homeostasis caused by imbalance in their functional composition and metabolic activities, known as dysbiosis, cause dysregulation of these pathways and trigger changes in the blood-brain barrier permeability, thereby causing pathological malfunctions, including neurological and functional gastrointestinal disorders. In turn, the brain can affect the structure and function of gut microbiota through the autonomic nervous system by regulating gut motility, intestinal transit and secretion, and gut permeability. Here, we examine data from the CAS Content Collection, the largest collection of published scientific information, and analyze the publication landscape of recent research. We review the advances in knowledge related to the human gut microbiome, its complexity and functionality, its communication with the central nervous system, and the effect of the gut microbiome-brain axis on mental and gut health. We discuss correlations between gut microbiota composition and various diseases, specifically gastrointestinal and mental disorders. We also explore gut microbiota metabolites with regard to their impact on the brain and gut function and associated diseases. Finally, we assess clinical applications of gut-microbiota-related substances and metabolites with their development pipelines. We hope this review can serve as a useful resource in understanding the current knowledge on this emerging field in an effort to further solving of the remaining challenges and fulfilling its potential.

Links between Diet, Intestinal Anaerobes, Microbial Metabolites and Health

A dense microbial community resides in the human colon, with considerable inter-individual variability in composition, although some species are relatively dominant and widespread in healthy individuals. In disease conditions, there is often a reduction in microbial diversity and perturbations in the composition of the microbiota. Dietary complex carbohydrates that reach the large intestine are important modulators of the composition of the microbiota and their primary metabolic outputs. Specialist gut bacteria may also transform plant phenolics to form a spectrum of products possessing antioxidant and anti-inflammatory activities. Consumption of diets high in animal protein and fat may lead to the formation of potentially deleterious microbial products, including nitroso compounds, hydrogen sulphide, and trimethylamine. Gut anaerobes also form a range of secondary metabolites, including polyketides that may possess antimicrobial activity and thus contribute to microbe-microbe interactions within the colon. The overall metabolic outputs of colonic microbes are derived from an intricate network of microbial metabolic pathways and interactions; however, much still needs to be learnt about the subtleties of these complex networks. In this review we consider the multi-faceted relationships between inter-individual microbiota variation, diet, and health.

HMOs Exert Marked Bifidogenic Effects on Children's Gut Microbiota Ex Vivo, Due to Age-Related Bifidobacterium Species Composition

Prebiotics are substrates that are selectively utilized by host microorganisms, thus conferring a health benefit. There is a growing awareness that interpersonal and age-dependent differences in gut microbiota composition impact prebiotic effects. Due to the interest in using human milk oligosaccharides (HMOs) beyond infancy, this study evaluated how HMOs [2'Fucosyllactose (2'FL), Lacto-N-neotetraose (LNnT), 3'Sialyllactose (3'SL), 6'Sialyllactose (6'SL)] and blends thereof affect the microbiota of 6-year-old children (n = 6) and adults (n = 6), compared to prebiotics inulin (IN) and fructooligosaccharides (FOS). The ex vivo SIFR® technology was used, given its demonstrated predictivity in clinical findings. First, HMOs and HMO blends seemed to maintain a higher α-diversity compared to FOS/IN. Further, while 2'FL/LNnT were bifidogenic for both age groups, 3'SL/6'SL and FOS/IN were exclusively bifidogenic for children and adults, respectively. This originated from age-related differences in microbiota composition because while 3'SL/6'SL stimulated B. pseudocatenulatum (abundant in children), FOS/IN enhanced B. adolescentis (abundant in adults). Moreover, all treatments significantly increased acetate, propionate and butyrate (only in adults) with product- and age-dependent differences. Among the HMOs, 6'SL specifically stimulated propionate (linked to Bacteroides fragilis in children and Phocaeicola massiliensis in adults), while LNnT stimulated butyrate (linked to Anaerobutyricum hallii in adults). Indole-3-lactic acid and 3-phenyllactic acid (linked to immune health) and gamma-aminobutyric acid (linked to gut-brain axis) were most profoundly stimulated by 2'FL and HMO blends in both children and adults, correlating with specific Bifidobacteriaceae. Finally, 2'FL/LNnT increased melatonin in children, while 3'SL remarkably increased folic acid in adults. Overall, age-dependent differences in microbiota composition greatly impacted prebiotic outcomes, advocating for the development of age-specific nutritional supplements. HMOs were shown to be promising modulators in the adult, and particularly the children's microbiota. The observed HMO-specific effects, likely originating from their structural heterogeneity, suggest that blends of different HMOs could maximize treatment effects.

Regulation of Physiological Barrier Function by the Commensal Microbiota

A fundamental characteristic of living organisms is their ability to separate the internal and external environments, a function achieved in large part through the different physiological barrier systems and their component junctional molecules. Barrier integrity is subject to multiple influences, but one that has received comparatively little attention to date is the role of the commensal microbiota. These microbes, which represent approximately 50% of the cells in the human body, are increasingly recognized as powerful physiological modulators in other systems, but their role in regulating barrier function is only beginning to be addressed. Through comparison of the impact commensal microbes have on cell-cell junctions in three exemplar physiological barriers-the gut epithelium, the epidermis and the blood-brain barrier-this review will emphasize the important contribution microbes and microbe-derived mediators play in governing barrier function. By extension, this will highlight the critical homeostatic role of commensal microbes, as well as identifying the puzzles and opportunities arising from our steadily increasing knowledge of this aspect of physiology.

Gut Microbiota in Colorectal Cancer: Biological Role and Therapeutic Opportunities

Colorectal cancer (CRC) is the second-leading cause of cancer-related deaths worldwide. While CRC is thought to be an interplay between genetic and environmental factors, several lines of evidence suggest the involvement of gut microbiota in promoting inflammation and tumor progression. Gut microbiota refer to the ~40 trillion microorganisms that inhabit the human gut. Advances in next-generation sequencing technologies and metagenomics have provided new insights into the gut microbial ecology and have helped in linking gut microbiota to CRC. Many studies carried out in humans and animal models have emphasized the role of certain gut bacteria, such as Fusobacterium nucleatum, enterotoxigenic Bacteroides fragilis, and colibactin-producing Escherichia coli, in the onset and progression of CRC. Metagenomic studies have opened up new avenues for the application of gut microbiota in the diagnosis, prevention, and treatment of CRC. This review article summarizes the role of gut microbiota in CRC development and its use as a biomarker to predict the disease and its potential therapeutic applications.

A host-gut microbial amino acid co-metabolite, p-cresol glucuronide, promotes blood-brain barrier integrity in vivo

The sequential activity of gut microbial and host processes can exert a powerful modulatory influence on dietary components, as exemplified by the metabolism of the amino acids tyrosine and phenylalanine to p-cresol by gut microbes, and then to p-cresol glucuronide (pCG) by host enzymes. Although such glucuronide conjugates are classically thought to be biologically inert, there is accumulating evidence that this may not always be the case. We investigated the activity of pCG, studying its interactions with the cerebral vasculature and the brain in vitro and in vivo. Male C57Bl/6 J mice were used to assess blood-brain barrier (BBB) permeability and whole-brain transcriptomic changes in response to pCG treatment. Effects were then further explored using the human cerebromicrovascular endothelial cell line hCMEC/D3, assessing paracellular permeability, transendothelial electrical resistance and barrier protein expression. Mice exposed to pCG showed reduced BBB permeability and significant changes in whole-brain transcriptome expression. Surprisingly, treatment of hCMEC/D3 cells with pCG had no notable effects until co-administered with bacterial lipopolysaccharide, at which point it was able to prevent the permeabilizing effects of endotoxin. Further analysis suggested that pCG acts as an antagonist at the principal lipopolysaccharide receptor TLR4. The amino acid phase II metabolic product pCG is biologically active at the BBB, antagonizing the effects of constitutively circulating lipopolysaccharide. These data add to the growing literature showing glucuronide conjugates to be more than merely metabolic waste products and highlight the complexity of gut microbe to host communication pathways underlying the gut-brain axis.

Interlink between the gut microbiota and inflammation in the context of oxidative stress in Alzheimer's disease progression

The microbiota-gut-brain axis is an important pathway of communication and may dynamically contribute to Alzheimer's disease (AD) pathogenesis. Pathological commensal gut microbiota alterations, termed as dysbiosis, can influence intestinal permeability and break the blood-brain barrier which may trigger AD pathogenesis via redox signaling, neuronal, immune, and metabolic pathways. Dysbiosis increases the oxidative stress. Oxidants affect the innate immune system through recognizing microbial-derived pathogens by Toll-like receptors and initiating the inflammatory process. Most of the gut microbiome research work highlights the relationship between the gut microbiota and AD, but the contributory connection between precise bacteria and brain dysfunction in AD pathology cannot be fully demonstrated. Here, we summarize the current information of the fundamental connections between oxidative stress, inflammation, and gut dysbiosis in AD. This review emphasizes on the involvement of gut microbiota in the regulation of oxidative stress, inflammation, immune responses including central and peripheral cross-talk. It provides insights for novel preventative and therapeutic approaches in AD.

New insights into immunomodulatory properties of lactic acid bacteria fermented herbal medicines

The COVID-19 pandemic has brought more attention to the immune system, the body’s defense against infectious diseases. The immunomodulatory ability of traditional herbal medicine has been confirmed through clinical trial research, and has obvious advantages over prescription drugs due to its high number of potential targets and low toxicity. The active compounds of herbal drugs primarily include polysaccharides, saponins, flavonoids, and phenolics and can be modified to produce new active compounds after lactic acid bacteria (LAB) fermentation. LAB, primary source of probiotics, can produce additional immunomodulatory metabolites such as exopolysaccharides, short-chain fatty acids, and bacteriocins. Moreover, several compounds from herbal medicines can promote the growth and production of LAB-based immune active metabolites. Thus, LAB-mediated fermentation of herbal medicines has become a novel strategy for regulating human immune responses. The current review discusses the immunomodulatory properties and active compounds of LAB fermented herbal drugs, the interaction between LAB and herbal medicines, and changes in immunoregulatory components that occur during fermentation. This study also discusses the mechanisms by which LAB-fermented herbal medicines regulate the immune response, including activation of the innate or adaptive immune system and the maintenance of intestinal immune homeostasis.

Alterations of the gut microbiota and short chain fatty acids in necrotizing enterocolitis and food protein-induced allergic protocolitis infants: A prospective cohort study

Background

Even though presenting with similar clinical manifestations, necrotizing enterocolitis (NEC) and food protein-induced allergic protocolitis (FPIAP) have completely different treatments and prognosis. Our study aimed to quantify and evaluate differences in gut microbiota and short chain fatty acids (SCFAs) between infants with NEC and FPIAP to better identify these two diseases in clinical settings.

Methods

A total of 43 infants with NEC or FPIAP in Children's Hospital of Chongqing Medical University, China between December 2020 and December 2021 were enrolled. Stool samples were prospectively collected and froze. Infants defined as NEC were those who presented with clinical courses consistent with NEC and whose radiographs fulfilled criteria for Bell's stage 2 or 3 NEC, while those who were healthy in appearance and had blood in the stool (visible or may be microscopic), had normal bowel sounds in physical examination, were resolved after eliminating the causative food, and/or had recurrence of symptoms after oral food challenge (OFC) were defined as FPIAP. Primers specific for bacterial 16S rRNA genes were used to amplify and pyrosequence fecal DNA from stool samples. Gas chromatography-mass spectrometry (GC-MS) technology was used to determine the concentrations of SCFAs.

Results

Among the 43 infants, 22 were diagnosed with NEC and 21 were diagnosed with FPIAP. The microbial community structure in NEC infant stools differed significantly from those in FPIAP infant stools. NEC infants had significantly higher proportion of Actinobacteria and reduced proportion of Bacteroidetes compared with FPIAP infants, and the proportions of Halomonas, Acinetobacter, Bifidobacterium, and Stenotrophomonas in NEC infants were significantly higher than that of FPIAP infants. In addition, infants with NEC had significantly lower levels of acetic acid, propionic acid, butyric acid, isovaleric acid, and total SCFAs, and higher level of hexanoic acid as compared to the infants of the FPIAP group.

Conclusions

The differences of gut microbiota composition and concentrations of SCFAs might represent suitable biomarker targets for early identification of NEC and FPIAP.

Microbiota-derived metabolites as drivers of gut-brain communication

Alterations in the gut microbiota composition have been associated with a range of neurodevelopmental, neurodegenerative, and neuropsychiatric disorders. The gut microbes transform and metabolize dietary- and host-derived molecules generating a diverse group of metabolites with local and systemic effects. The bi-directional communication between brain and the microbes residing in the gut, the so-called gut-brain axis, consists of a network of immunological, neuronal, and endocrine signaling pathways. Although the full variety of mechanisms of the gut-brain crosstalk is yet to be established, the existing data demonstrates that a single metabolite or its derivatives are likely among the key inductors within the gut-brain axis communication. However, more research is needed to understand the molecular mechanisms underlying how gut microbiota associated metabolites alter brain functions, and to examine if different interventional approaches targeting the gut microbiota could be used in prevention and treatment of neurological disorders, as reviewed herein.Abbreviations:4-EPS 4-ethylphenylsulfate; 5-AVA(B) 5-aminovaleric acid (betaine); Aβ Amyloid beta protein; AhR Aryl hydrocarbon receptor; ASD Autism spectrum disorder; BBB Blood-brain barrier; BDNF Brain-derived neurotrophic factor; CNS Central nervous system; GABA ɣ-aminobutyric acid; GF Germ-free; MIA Maternal immune activation; SCFA Short-chain fatty acid; 3M-4-TMAB 3-methyl-4-(trimethylammonio)butanoate; 4-TMAP 4-(trimethylammonio)pentanoate; TMA(O) Trimethylamine(-N-oxide); TUDCA Tauroursodeoxycholic acid; ZO Zonula occludens proteins.

Paradigm Shift in Phytochemicals Research: Evolution from Antioxidant Capacity to Anti-Inflammatory Effect and to Roles in Gut Health and Metabolic Syndrome

Food bioactive components, particularly phytochemicals with antioxidant capacity, have been extensively studied over the past two decades. However, as new analytical and molecular biological tools advance, antioxidants related research has undergone significant paradigm shifts. This review is a high-level overview of the evolution of phytochemical antioxidants research. Early research used chemical models to assess the antioxidant capacity of different phytochemicals, which provided important information about the health potential, but the results were overused and misinterpreted despite the lack of biological relevance (Antioxidants v1.0). This led to findings in the anti-inflammatory properties and modulatory effects of cell signaling of phytochemicals (Antioxidants v2.0). Recent advances in the role of diet in modulating gut microbiota have suggested a new phase of food bioactives research along the phytochemicals-gut microbiota-intestinal metabolites-low-grade inflammation-metabolic syndrome axis (Antioxidants v3.0). Polyphenols and carotenoids were discussed in-depth, and future research directions were also provided.

Akkermansia muciniphila and Gut Immune System: A Good Friendship That Attenuates Inflammatory Bowel Disease, Obesity, and Diabetes

Akkermansia muciniphila is a Gram-negative anaerobic mucus-layer-degrading bacterium that colonizes the intestinal mucosa of humans and rodents. Metagenomic data have shown an inverse correlation between the abundance of A. muciniphila and diseases such as inflammatory bowel disease (IBD), obesity, and diabetes. Thus, in recent decades, the potential of this bacterium as an immunomodulatory probiotic for autoimmune and chronic inflammatory diseases has been explored in experimental models. Corroborating these human correlation data, it has been reported that A. muciniphila slows down the development and progression of diabetes, obesity, and IBD in mice. Consequently, clinical studies with obese and diabetic patients are being performed, and the preliminary results are very promising. Therefore, this mini review highlights the main findings regarding the beneficial roles of A. muciniphila and its action mechanisms in autoimmune and chronic inflammatory diseases.

Alteration of Gut Microbiota in Alzheimer's Disease and Their Relation to the Cognitive Impairment

BACKGROUND

Dysbiosis of gut microbiota has been reported to be enrolled in the pathogenesis of Alzheimer's disease (AD). However, there is a lack of relevant studies on this topic in Egyptian patients with AD.

OBJECTIVE

To investigate different species of gut microbiota in Egyptian patients with AD and correlate microbiota bacterial abundance with clinical data.

METHODS

The study included 25 patients with AD and 25 healthy volunteers as age and sex-matched controls. Clinical data was taken for each patient, including medical history and examination; Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were assessed for each participant. Bacterial DNA was extracted from stool, and abundance quantified via qPCR using 16S rRNA group-specific primers.

RESULTS

Akkermansia, Enterobacteria, Bacteroidetes, Bacillus cereus, Prevotella, and Clostridium cluster IV were more abundant in the AD group than in the control group, although there was significantly less abundance of Bifidobacterium spp., Firmicutes, and Actinobacteria in patients with AD than in controls, whereas no such significance was found for lactic acid bacteria between both groups. Lactic acid bacteria and Prevotella abundance was negatively correlated with cognitive impairment (p = 0.03 with MMSE, and p = 0.03 with MoCA). Prevotella abundance was positively correlated with age of onset and duration of illness and negatively correlated with smoking and coronary heart disease (p = 0.007, p = 0.03, p = 0.035, and p = 0.047, respectively).

CONCLUSION

The current work highlighted a significant relationship between AD and gut microbiota dysbiosis. A higher abundance of Prevotella species and lactic acid bacteria was correlated with cognition.

Trust Your Gut: The Association of Gut Microbiota and Liver Disease

The gut microbiota composition is important for nutrient metabolism, mucosal barrier function, immunomodulation, and defense against pathogens. Alterations in the gut microbiome can disturb the gut ecosystem. These changes may lead to the loss of beneficial bacteria or an increase in potentially pathogenic bacteria. Furthermore, these have been shown to contribute to the pathophysiology of gastrointestinal and extra-intestinal diseases. Pathologies of the liver, such as non-alcoholic liver disease, alcoholic liver disease, cirrhosis, hepatocellular carcinoma, autoimmune hepatitis, viral hepatitis, and primary sclerosing cholangitis have all been linked to changes in the gut microbiome composition. There is substantial evidence that links gut dysbiosis to the progression and complications of these pathologies. This review article aimed to describe the changes seen in the gut microbiome in liver diseases and the association between gut dysbiosis and liver disease, and finally, explore treatment options that may improve gut dysbiosis in patients with liver disease.

Cysteinyl leukotrienes and acetylcholine are biliary tuft cell cotransmitters

The gallbladder stores bile between meals and empties into the duodenum upon demand and is thereby exposed to the intestinal microbiome. This exposure raises the need for antimicrobial factors, among them, mucins produced by cholangiocytes, the dominant epithelial cell type in the gallbladder. The role of the much less frequent biliary tuft cells is still unknown. We here show that propionate, a major metabolite of intestinal bacteria, activates tuft cells via the short-chain free fatty acid receptor 2 and downstream signaling involving the cation channel transient receptor potential cation channel subfamily M member 5. This results in corelease of acetylcholine and cysteinyl leukotrienes from tuft cells and evokes synergistic paracrine effects upon the epithelium and the gallbladder smooth muscle, respectively. Acetylcholine triggers mucin release from cholangiocytes, an epithelial defense mechanism, through the muscarinic acetylcholine receptor M3. Cysteinyl leukotrienes cause gallbladder contraction through their cognate receptor CysLTR1, prompting emptying and closing. Our results establish gallbladder tuft cells as sensors of the microbial metabolite propionate, initiating dichotomous innate defense mechanisms through simultaneous release of acetylcholine and cysteinyl leukotrienes.

Aloe vera and Fermented Extracts Exhibit an Anti-Inflammatory Effect on Human Glioblastoma/Astrocytoma U373 MG Cells

The anti-inflammatory effects of Aloe vera (AV), polysaccharide extract from AV, and extracts from the digestion and colonic fermentation of AV were evaluated using an immortal astrocyte cell line (U373 MG) that develops a neuro-inflammatory profile. Cell viability and inflammatory markers were assessed after stimulation with neuropeptide substance P (SP) that activates the pro-inflammatory MAPK (mitogen-activated protein kinase) pathway. Cell viability after SP treatment was over 50% at 10 mg/mL AV, polysaccharide extract from AV, extracts from the digestion: non-digestible fraction of AV non-digestible fraction of polysaccharide extract from AV and extracts from the colonic fermentation of AV, at 4 and 24 h. Moreover, cells exposed to SP and treated with these extracts showed lower protein-activated ERK1/ERK2 (extracellular signal-regulated kinases 1 and 2), p38 (MAPK protein p38), and NFκB (nuclear factor κB) levels with respect to the SP-stimulated control. Inflammation inhibition by extracts of polysaccharide extract from AV and extracts from the colonic fermentation of AV, at 24 h in the study of p38 was not as statistically significant in ERK1/ERK2 and NFκB. Nevertheless, there was a significant decrease (p < 0.05) in pro-inflammatory cytokine IL-6 levels in cells exposed to all samples. Samples with extracts from the colonic fermentation of AV, at 4 or 24 h showed the highest inhibitory effect on IL-6 production.

Development of gut microbiota along with its metabolites of preschool children

Background

To reveal the changes of intestinal microbial abundance and composition, as well as the microbiota metabolic levels of bile acids and short chain fatty acids of healthy preschool children during their growth.

Methods

Feces of 120 healthy newborns and 150 healthy children aged 6 months to 6 years were collected. Then the composition of intestinal flora was analyzed by 16S rRNA, and the contents of bile acids and short chain fatty acids in feces were detected by LC-MS and GS methods, respectively.

Results

The composition and function of intestinal microflora were not stable in neonatal period but significantly improved at 6 months after birth, and gradually stabilized and tended to adult-like formation after 2–3 years old. The levels of short chain fatty acids and secondary bile acids were consistent with the development of gut microbiota.

Conclusion

The age of 6 months may be a critical period for the development of intestinal microflora in children.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-03099-9.

GPR40 Agonist Ameliorate Pathological Neuroinflammation of Alzheimer's Disease via the Modulation of Gut Microbiota and Immune System, a Mini-Review

Alzheimer's disease (AD) is a central disease with high incidence, and its pathological process is closely associated with changes of some biological indicators in the periphery. Among them, the intestinal flora mainly causes a series of pathological changes such as inflammation through the immune system, which may contribute to the pathological process of AD. In this paper, we mainly focused the relationship between gut microbiota and immune system disorder in the neuropathology of AD, underlining the significance of the advanced mechanism of inflammatory response and providing a new direction for the treatment of AD.

A non-optimal cervicovaginal microbiota in pregnancy is associated with a distinct metabolomic signature among non-Hispanic Black individuals

Biomechanical and molecular processes of premature cervical remodeling preceding spontaneous preterm birth (sPTB) likely result from interactions between the cervicovaginal microbiota and host immune responses. A non-optimal cervicovaginal microbiota confers increased risk of sPTB. The cervicovaginal space is metabolically active in pregancy; microbiota can produce, modify, and degrade metabolites within this ecosystem. We establish that cervicovaginal metabolomic output clusters by microbial community in pregnancy among Black individuals, revealing increased metabolism within the amino acid and dipeptide pathways as hallmarks of a non-optimal microbiota. Few differences were detected in metabolomic profiles when stratified by birth outcome. The study raises the possibility that metabolites could distinguish women with greater risk of sPTB among those with similar cervicovaginal microbiota, and that metabolites within the amino acid and carbohydrate pathways may play a role in this distinction.

Long-Term Overconsumption of Fat and Sugar Causes a Partially Reversible Pre-inflammatory Bowel Disease State

Nutrition appears to be an important environmental factor involved in the onset of inflammatory bowel diseases (IBD) through yet poorly understood biological mechanisms. Most studies focused on fat content in high caloric diets, while refined sugars represent up to 40% of caloric intake within industrialized countries and contribute to the growing epidemics of inflammatory diseases. Herein we aim to better understand the impact of a high-fat-high-sucrose diet on intestinal homeostasis in healthy conditions and the subsequent colitis risk. We investigated the early events and the potential reversibility of high caloric diet-induced damage in mice before experimental colitis. C57BL/6 mice were fed with a high-fat or high-fat high-sucrose or control diet before experimental colitis. In healthy mice, a high-fat high-sucrose diet induces a pre-IBD state characterized by gut microbiota dysbiosis with a total depletion of bacteria belonging to Barnesiella that is associated with subclinical endoscopic lesions. An overall down-regulation of the colonic transcriptome converged with broadly decreased immune cell populations in the mesenteric lymph nodes leading to the inability to respond to tissue injury. Such in-vivo effects on microbiome and transcriptome were partially restored when returning to normal chow. Long-term consumption of diet enriched in sucrose and fat predisposes mice to colitis. This enhanced risk is preceded by gut microbiota dysbiosis and transcriptional reprogramming of colonic genes related to IBD. Importantly, diet-induced transcriptome and microbiome disturbances are partially reversible after switching back to normal chow with persistent sequelae that may contribute to IBD predisposition in the general population.

Dietary fibre complexity and its influence on functional groups of the human gut microbiota

The aim of this review is to provide an overview of the complex interactions between dietary fibre and the resident microbial community in the human gut. The microbiota influences both health maintenance and disease development. In the large intestine, the microbiota plays a crucial role in the degradation of dietary carbohydrates that remain undigested in the upper gut (non-digestible carbohydrates or fibre). Dietary fibre contains a variety of different types of carbohydrates, and its breakdown is facilitated by many different microbial enzymes. Some microbes, termed generalists, are able to degrade a range of different carbohydrates, whereas others are more specialised. Furthermore, the physicochemical characteristics of dietary fibre, such as whether it enters the gut in soluble or insoluble form, also likely influence which microbes can degrade it. A complex nutritional network therefore exists comprising primary degraders able to attack complex fibre and cross feeders that benefit from fibre breakdown intermediates or fermentation products. This leads predominately to the generation of the short-chain fatty acids (SCFA) acetate, propionate and butyrate, which exert various effects on host physiology, including the supply of energy, influencing glucose and lipid metabolism and anti-carcinogenic and anti-inflammatory actions. In order to effectively modulate the gut microbiota through diet, there is a need to better understand the complex competitive and cooperative interactions between gut microbes in dietary fibre breakdown, as well as how gut environmental factors and the physicochemical state of fibre originating from different types of diets influence microbial metabolism and ecology in the gut.