Gut microbiota-derived short-chain Fatty acids, T cells, and inflammation

The effects of Saccharomyces boulardii on rat colonic hypermotility induced by repeated water avoidance stress and the potential mechanism

Background

Saccharomyces boulardii (Sb) has been reported to have the potential to regulate gut motility. The aim of this experiment was to explore the possible function of Sb in gut hypermotility elicited by repeated water avoidance stress (WAS).

Methods

Adult male Wistar rats (N = 24) were divided into one of the following three groups: control (C), NS (normal saline) + WAS group (N), and Sb + WAS group (S). A diarrhea-predominant irritable bowel syndrome (IBS-D) model in rats was induced using the WAS method. Gut motility was evaluated by stool pellet expulsion per hour. The contractile activity of the colonic muscle strips was measured using an RM6240 multichannel physiological signal instrument. qRT-PCR and immunohistochemistry were used to assess Toll-like receptor 4 (TLR4) expression in colon tissue. ELISA was used to measure the level of cytokines in the serum and colonic tissue. Also, the microbiota composition was determined using high-throughput 16S rRNA sequencing.

Result

The results showed that oral Sb decreased the WAS-induced increased defecation and colonic hypermotility in vivo. Furthermore, Sb also decreased the contractile amplitude of colonic circular muscle (CM) and longitudinal muscle (LM) strips in a dose-dependent manner in vitro. Repeated WAS increased TLR4 expression, but Sb reversed it. Sb also reduced interleukin-6 (IL-6), IL-1β, and interferon-γ (IFN-γ) levels in serum and colonic tissue, while increasing IL-10 levels in colonic tissue. Meanwhile, the rats from the NS + WAS group had decreased microbiota diversity and had lower relative abundances of Patescibacteria, Epsilonbacteraeota, Cyanobacteria, and Turicibacter compared with controls. The rats in the Sb + WAS group showed a tendency to increase the relative abundance of Blautia when compared to control rats and had lower relative abundances of Acidobacteria and Anaerostipes compared with the NS + WAS group.

Conclusion

Our findings demonstrated that Sb improved colonic hypermotility in rats, reversed the high-expression of TLR4 in the colon caused by repeated WAS, modulated cytokines in the colon and serum, and altered the gut microbiota, indicating that Sb may be useful for IBS-D.

Modulation of the porcine intestinal microbiota in the course of Ascaris suum infection

Background

The porcine roundworm Ascaris suum impairs feed conversion and weight gain, but its effects on intestinal microbiota remain largely unexplored.

Methods

Modulation of the intestinal microbiota was assessed in pigs that were infected once with 10,000 A. suum eggs and pigs that received a trickle infection (1000 eggs/day over 10 days), compared with a non-infected control group. Six pigs each were sacrificed per group at days 21, 35 and 49 post-infection (p.i.). Faecal samples taken weekly until slaughter and ingesta samples from different intestinal compartments were subjected to next-generation sequencing of the bacterial 16S rRNA gene.

Results

The results revealed marked differences between the single- and the trickle-infected group. Single infection caused a remarkable but transient decrease in microbial diversity in the caecum, which was not observed in the trickle-infected group. However, an increase in short-chain fatty acid-producing genera in the caecum on day 21 p.i., which shifted to a decrease on day 35 p.i., was common to both groups, possibly related to changes in excretory–secretory products following the parasite’s final moult. Faecal microbial interaction networks were more similar between the single-infected and control group than the trickle-infected group. In addition, a lower degree of similarity over time indicated that A. suum trickle infection prevented microbiota stabilization.

Conclusions

These different patterns may have important implications regarding the comparability of experimental infections with natural scenarios characterized by continuous exposure, and should be confirmed by further studies.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05535-w.

Intestinal Microbiota Correction in the Treatment and Prevention of Urinary Tract Infection

Intestinal microbiota is a topical subject of modern research. The maintenance of a healthy intestinal micro biota is an important component of homeostasis, and violations of its composition and functions, called dysbiosis, are associated with a number of diseases, including urinary tract infections. Antimicrobial therapy leads to significant changes in the intestinal microbiota and causes the possibility of urinary tract infection recurrence. In this regard, it is important to study methods of microbiota correction in order to restore its structural and functional integrity.

Recent advances in modulation of cardiovascular diseases by the gut microbiota

The gut microbiota has recently gained attention due to its association with cardiovascular health, cancers, gastrointestinal disorders, and non-communicable diseases. One critical question is how the composition of the microbiota contributes to cardiovascular diseases (CVDs). Insightful reviews on the gut microbiota, its metabolites and the mechanisms that underlie its contribution to CVD are limited. Hence, the aim of this review was to describe linkages between the composition of the microbiota and CVD, CVD risk factors such as hypertension, diet, ageing, and sex differences. We have also highlighted potential therapies for improving the composition of the gut microbiota, which may result in better cardiovascular health.

The synergistic interaction of systemic inflammation, dysbiosis and antimicrobial resistance promotes growth restriction in children with acute severe malnutrition: An emphasis on Escherichia coli

A healthy development is denied to millions of children worldwide as harsh life conditions manifest themselves in an altered inflammation-prone microbiome crosstalk environment. Keynote of this tragedy is that insufficient nutritious amino acid blocks lipids-intake to sustain diverse microbiota, and promotes the generalist strategy followed by Escherichia coli -besides other proteobacteria- of shifting gut metabolism, subverting the site specificity of first immune reaction. Furthermore, it could be hypothesized that selective success lies in their ability to induce inflammation, since this phenomenon also fuels horizontal gene transfer (HGT). In this review, we dilucidate how immune mechanisms of environmental enteric dysfunction affect overgrowth restriction, infectious morbidity rate, and acquired lifelong risks among severe acute malnourished children. Also, despite acknowledging complexities of antimicrobial resistant enrichment, we explore and speculate over the links between virulence regulation and HGT as an indissociable part in the quest for new inflammatory niches by open genome bacteria, particularly when both collide in the most vulnerable.

The role of the gut microbiota in health and cardiovascular diseases

The gut microbiota is critical to human health, such as digesting nutrients, forming the intestinal epithelial barrier, regulating immune function, producing vitamins and hormones, and producing metabolites to interact with the host. Meanwhile, increasing evidence indicates that the gut microbiota has a strong correlation with the occurrence, progression and treatment of cardiovascular diseases (CVDs). In patients with CVDs and corresponding risk factors, the composition and ratio of gut microbiota have significant differences compared with their healthy counterparts. Therefore, gut microbiota dysbiosis, gut microbiota-generated metabolites, and the related signaling pathway may serve as explanations for some of the mechanisms about the occurrence and development of CVDs. Several studies have also demonstrated that many traditional and latest therapeutic treatments of CVDs are associated with the gut microbiota and its generated metabolites and related signaling pathways. Given that information, we summarized the latest advances in the current research regarding the effect of gut microbiota on health, the main cardiovascular risk factors, and CVDs, highlighted the roles and mechanisms of several metabolites, and introduced corresponding promising treatments for CVDs regarding the gut microbiota. Therefore, this review mainly focuses on exploring the role of gut microbiota related metabolites and their therapeutic potential in CVDs, which may eventually provide better solutions in the development of therapeutic treatment as well as the prevention of CVDs.

Deeper insight into the role of IL-17 in the relationship beween hypertension and intestinal physiology

With the incidence of hypertension increasing worldwide, more and more the mechanisms of hypertension from the perspective of immunity have found. Intestinal microbiota as well as its metabolites relationship with hypertension has attracted great attention from both clinicians and investigators. However, the associations of hypertension with lesions of a large number of immune factors including IL-17, MCP-1, IL-6, TGF-β, IL-10 and others have not been fully characterized. In this review, after introducing the immune factors as the most potent anti/pro-hypertension agents known, we provide detailed descriptions of the IL-17 involved in the pathology of hypertension, pointing out the underlying mechanisms and suggesting the clinical indications.

Peptides, Exopolysaccharides, and Short-Chain Fatty Acids from Fermented Milk and Perspectives on Inflammatory Bowel Diseases

Crohn's disease and ulcerative colitis are characterized by chronic inflammatory processes and an imbalanced immune response along the gastrointestinal (GI) tract. Pharmacological treatments have been widely used, although their long-term application has adverse side effects. On the other hand, milks fermented with specific lactic acid bacteria (LAB) have been shown to be useful as alternative or complementary aids. Many metabolites such as peptides, exopolysaccharides, and short-chain fatty acids are produced during milk fermentation. These components have been shown to change the pH of the gastrointestinal lumen, aid intestine mucosal recovery, modulate the microbiota, and reduce the inflammatory response (innate and adaptive immune system), both in vitro and in vivo. Therefore, the objective of the present review is to describe how these bioactive compounds from fermented milk by specific LAB can decrease the deleterious symptoms of inflammatory bowel disease.

The potential mechanism of Liu-Wei-Di-Huang Pills in treatment of type 2 diabetic mellitus: from gut microbiota to short-chain fatty acids metabolism

BACKGROUND

Type 2 diabetes mellitus (T2DM) has already become a global pandemic. Recently, reports showed its pathogenesis was closely related to a disorder of gut microbiota. In China, the Liu-Wei-Di-Huang Pills (LWDH) have treated T2DM for thousands of years. However, its therapeutic mechanism associated with gut microbiota is worthy of further study.

AIMS

This study aims to investigate the effects of LWDH on T2DM by regulating gut microbiota and short-chain fatty acids (SCFAs) in Goto-Kakizaki (GK) rats.

METHODS

T2DM models were successfully established based on GK rats and administrated with LWDH. The changes in fasting blood glucose (FBG), oral glucose tolerance test (OGTT), and serum insulin (INS) were determined, and the immunohistochemical (IHC) method was used to test INS expression in pancreas. The 16S-ribosomal DNA (16S rDNA) sequencing analysis assessed gut microbiota structural changes; a gas chromatography-mass spectrometer (GC-MS)-based metabolomics method was adopted to detect SCFA levels. The pathological morphology of jejunum was detected by hematoxylin-eosin (H&E) staining, and the expression of GPR43, GPR41, GLP-1, and GLP-1R was evaluated by qRT-PCR and ELISA, respectively.

RESULTS

We observed that GK rats treated with LWDH: (a) has altered the microbial structure and promoted the abundance of bacteria in Firmicutes, including Lactobacillus, Allobaculum, and Ruminococcus_2, (b) increased SCFAs levels involving acetic acid, propionic acid, and butyric acid and (c) alleviated T2DM and jejunum injuries potentially based on SCFAs-GPR43/41-GLP-1 pathway.

CONCLUSION

LWDH could improve T2DM by regulating gut microbiota and SCFAs, and the therapeutic mechanism might be related to the SCFAs-GPR43/41-GLP-1 pathway.

Effects of fecal microbiota transplantation from yaks on weaning diarrhea, fecal microbiota composition, microbial network structure and functional pathways in Chinese Holstein calves

This study was conducted to investigate the effect of fecal microbiota transplantation (FMT) from yaks on weaning diarrhea, fecal microbiota composition, microbial network structure and functional pathways in Chinese Holstein Calves. In this study, 50 calves were randomly divided into five groups of 10 each: NC group (no supplementation), Control group (normal saline), low concentration FMT group (LFMT, 1 × 108 CFU/ml), high concentration FMT group (HMFT, 1 × 109 CFU/ml), and sterilized FMT group (SMFT, sterilized bacterial solution). The test lasted for 30 days. We found that FMT reduced the incidence of diarrhea in weaned calves, and the anti-diarrhea effect of LFMT was stronger than those of HFMT and SFMT. Calf feces were collected by rectal palpation on days 5, 10, 15, and 20 post-weaning, and high-throughput sequencing of bacterial 16S rRNA and fungal internal transcribed spacer region of fecal microbiota was performed. We observed that the richness and diversity of bacterial microbiota in the LFMT, HFMT, and SFMT groups were higher than those in the NC and Control groups at day 20 after weaning. The treatment had a significant effect on bacterial richness (p < 0.05), but not on fungal diversity or richness. The analysis of gut microbiome showed that Firmicutes and Bacteroides were the main bacterial phyla in the feces of weaned calves, and norank_ f Muribaculaceae, UCG-005, Rikenellaceae_RC9_gut_group, Bacteroides, and Blautia were the main genera. Ascomycota and Basidiomycota were the main fungal phyla. Compared to abundance parameters in the Control and NC groups, relative abundances of Firmicutes in the FMT groups increased at different time points after weaning. The relative abundance of Blautia and Lactobacillus in the LFMT group increased significantly after weaning. In addition, abundances of Ruminococcus and Romboutsia, which produce short-chain fatty acids, were also increased in different FMT groups. FMT significantly increased the relative abundance of beneficial bacteria, enhanced the complexity of the fecal microbial network, and promoted important metabolic and cellular processes in weaned calves. In conclusion, our study provides a reference and theoretical basis for FMT to prevent calf weaning diarrhea and other intestinal diseases in ruminants.

The Feed Additive Potassium Diformate Prevents Salmonella enterica Serovar Pullorum Infection and Affects Intestinal Flora in Chickens

Extensive studies have shown that potassium diformate (KDF), an antibiotic substitute used as a feed additive, improves animal growth performance, although there is less direct evidence of its preventive effect on bacterial infections and its influence on the intestinal flora of animals. In this study, the inhibition effect of KDF on Salmonella enterica serovar Pullorum, an important enteric pathogen causing pullorum disease, was investigated in vitro and on a chicken infection model. The effect of KDF on the diversities and structures of chicken duodenal and cecum flora were also investigated using 16S rRNA gene sequencing. The results showed that addition of 0.5% KDF in feed or 0.1% KDF in drinking water significantly reduced the bacterial loads and the degree of pathological changes in the cecum, improved digestion and reduced the pH of the gastrointestinal tract of chickens infected with S. pullorum. KDF also significantly modified the diversity and abundance of intestinal microflorae in chickens. In particular, it promoted the colonization of several probiotics, such as Bacteroides, Blautia, Ruminococcus_torques_group and Faecalibacteriumm, which are involved in maintenance of the intestinal barrier, modulation of inflammation, energy supply for intestinal cells and pathogen resistance. These results enrich the theoretical basis for the clinical application of KDF in chickens.

Hepatitis B x (HBx) as a Component of a Functional Cure for Chronic Hepatitis B

Patients who are carriers of the hepatitis B virus (HBV) are at high risk of chronic liver disease (CLD) which proceeds from hepatitis, to fibrosis, cirrhosis and to hepatocellular carcinoma (HCC). The hepatitis B-encoded X antigen, HBx, promotes virus gene expression and replication, protects infected hepatocytes from immunological destruction, and promotes the development of CLD and HCC. For virus replication, HBx regulates covalently closed circular (ccc) HBV DNA transcription, while for CLD, HBx triggers cellular oxidative stress, in part, by triggering mitochondrial damage that stimulates innate immunity. Constitutive activation of NF-κB by HBx transcriptionally activates pro-inflammatory genes, resulting in hepatocellular destruction, regeneration, and increased integration of the HBx gene into the host genome. NF-κB is also hepatoprotective, which sustains the survival of infected cells. Multiple therapeutic approaches include direct-acting anti-viral compounds and immune-stimulating drugs, but functional cures were not achieved, in part, because none were yet devised to target HBx. In addition, many patients with cirrhosis or HCC have little or no virus replication, but continue to express HBx from integrated templates, suggesting that HBx contributes to the pathogenesis of CLD. Blocking HBx activity will, therefore, impact multiple aspects of the host–virus relationship that are relevant to achieving a functional cure.

Integrated gut microbiota and metabolomic analysis reveals immunomodulatory effects of Echinacea extract and Astragalus polysaccharides

Immunosuppression in different animals increases the susceptibility of various infections caused by pathogenic microorganisms leading to increase risks posed by antibiotics in different animal farming sectors. Therefore, investigation of the interactions between natural medicines and the intestinal environmental ecosystem is of vital importance and crucial. This study for the first time investigated the effects of Echinacea Extract (EE) and Astragalus polysaccharide (APS) on the gut using 16S rRNA and metabolomic analysis approaches in immunosuppressed broiler chickens. There were four groups divided into control (C), immunosuppression (IS), EE, and APS groups. Sequencing of gut microbes showed that immunosuppression decreased the relative abundance of Anaerofustis, Anaeroplasma, Anaerotroncus, and Lachnospira in the gut while increasing that of c_115 and Holdemania. However, EE and APS diminished the effects on the immunosuppression on the microbiota. The results revealed up-regulation of the relative abundance of Enterococcus in broiler chickens. In addition, EE reduced the relative abundance of Ruminococcus and Blautia. The results on metabolomic analysis revealed that immunosuppression mainly affects cyanuric acid metabolism, starch and sucrose metabolism while interconversion of pentose and glucuronide. EE and APS, on the other hand mainly impact butyrate metabolism, alanine, aspartate and glutamate metabolism while the interconversion of pentose and glucuronide, and D-glutamine and D-glutamate metabolism. Results regarding correlation analysis revealed significantly metabolic pathways including TCA cycle, butyrate metabolism, glyoxylate and dicarboxylate metabolism, propionate metabolism, alanine, aspartate and glutamate metabolism associated with Ruminococcus and Blautia. Both EE and APS can antagonize the effects of immunosuppression by modulating the disrupted gut microbiota. Nevertheless, EE might have a bidirectional regulatory functions on the intestinal health and further studies are needed to know the exact and relevant mechanisms of action regarding the effects of EE and APS.

Improvement of anticancer effect of berberine by salt formation modifications

BACKGROUND

Berberine is a quaternary isoquinoline alkaloid that possesses a significant therapeutic effect on a variety of cancers. However, due to poor bioavailability, an increased dose is often required to achieve therapeutic goals. To improve the activities of natural berberine, most modifications were focused on the positive isoquinoline unit by grafting long aliphatic chains or heterocycles. However, the negative part is ignored. At this point, the strategy of salt formation modifications with short- and medium-chain fatty acids was proposed in this article.

PURPOSE

Using salt modification to enhance the antitumor activity of berberine and explore the mechanism.

METHODS

Four short- and medium-chain fatty acid salts of berberine were prepared from berberine hydrochloride by salt formation modification with the sodium salt of butyric, caproic, octanoic, and decanoic acid, respectively. The cytotoxicity of four berberine salts on B16-F10, A549, HepG2, and U373 cancer cell lines was explored. Through cell localization, Mitochondrial membrane potential assay, and Western blotting analysis explored the mechanism of berberine salt-induced apoptosis. Its anticancer activity in vivo was demonstrated by the mouse xenograft model.

RESULTS

The four berberine fatty acid salts exhibited an enhanced inhibitory effect on B16-F10, A549, HepG2, and U373 cancer cell lines, particularly on B16-F10 cells. Meanwhile, the four berberine fatty acid salts can inhibit the migration of B16-F10 cells. The four berberine fatty acid salts induce cancer cell apoptosis through the mitochondrial pathway, which was confirmed by the mitochondrial colocalization, the decreased mitochondrial membrane potential as well as activation of caspase-3, cytochrome C (Cyt-C), and down-regulated expression of B-cell lymphoma 2 (Bcl-2). Most importantly, the four berberine fatty acid salts inhibited tumor growth in the in vivo B16-F10 melanoma model without generating side effects intraperitoneally.

CONCLUSIONS

This study revealed that salt formation modification may be an effective strategy to optimize the anticancer property of berberine hydrochloride and demonstrated the four berberine fatty acid salts induced apoptosis through the mitochondrial apoptotic pathway.

Probiotics with anti-type 2 diabetes mellitus properties: targets of polysaccharides from traditional Chinese medicine

Traditional Chinese medicine polysaccharides is a biologically active ingredient that is not easy to be digested. It is fermented by intestinal microflora to promote qualitative and selective changes in the composition of the intestinal microbiome, which often result in beneficial effects on the health of the host. People call it "prebiotics". In this review, we systematically summarized the anti-diabetic effect of traditional Chinese medicine polysaccharides. These polysaccharides regulate the metabolism of sugar and lipids by inter-influence with the intestinal microflora, and maintain human health, while improving type 2 diabetes-like symptoms such as high blood glucose, and abnormal glucose and lipid metabolism.

Effects of Thermally-Oxidized Frying Oils (Corn Oil and Lard) on Gut Microbiota in Hamsters

Repeated reuse of frying oil raises health concerns due to the accumulation of oxidative products after each frying cycle. Gut microbiota is integral in lipid metabolism and immune regulation. The present study was designed to investigate the effects of thermally-oxidized corn oil and lard on gut microbiota in relation to atherosclerosis, inflammatory cytokines, and plasma lipids. Male Golden Syrian hamsters were randomly divided into four groups and fed one of four diets containing fresh corn oil (CF), oxidized corn oil (CO), fresh lard (LF), and oxidized lard (LO), for six weeks. CO and LO were prepared by deep-frying potatoes in corn oil or lard for seven days. Results indicated that oxidized oil and lard caused the loss of species diversity and richness of gut microbiota. Feeding CO and LO also reduced the body and adipose tissue weights, associated with genus Acetatifactor and Allobaculum. Plasma triacylglycerols significantly increased by 51% in the CO and 35% in the LO group compared with that in their CF and LF counterparts, respectively. CO could also affect the abundance of specific bacteria genera: Bacteroides, Barnesiella, Acetatifactor, Allobaculum, Clostridium_IV, Clostridium_XIVa, Coprococcus, Lactococcus, Paraprevotella, Parasutterella, and Oscillibacter. In addition, CO and LO could adversely remodel gut composition and affect intestinal production of short-chain fatty acids, pro-inflammatory biomarkers (LPS and IL-6), anti-inflammatory biomarker IL-10, and atherosclerotic progression. It was concluded that frying oil could adversely modulate the gut microbiota and exacerbate the atherosclerosis at least in a hypercholesterolemia hamster model.

A comparison of the composition and functions of the oral and gut microbiotas in Alzheimer’s patients

Objective

Alterations in the oral or gut microbiotas have been reported in patients with subjective and mild cognitive impairment or AD dementia. However, whether these microbiotas change with the severity of the AD spectrum (mild, moderate, and severe AD) remains unknown. Thus, we compared alterations in the composition and gene functions of the oral and gut microbiota between different phases of AD.

Methods

We recruited 172 individuals and classified these into three groups: healthy controls (n = 40), a mild AD group (n = 43) and a moderate AD group (n = 89). Subgingival plaques and fecal samples were collected from all individuals. Then, we conducted 16S ribosomal RNA. sequencing to analyze the microbiotas.

Results

In order of the severity of cognition impairment (from normal to mild and to moderate AD), the oral abundances of the phyla Firmicutes and Fusobacteria showed a gradual upwards trend, while the abundance of the Proteobacteria phylum gradually decreased. In contrast, the abundance of the Firmicutes and Bacteroidetes phyla in the gut decreased progressively, while that of the Proteobacteria, Verrucomicrobia and Actinobacteria phyla increased gradually. Key differences were identified in the microbiomes when compared between the mild AD and moderate AD groups when applying the linear discriminant analysis effect size (LEfSe) algorithm. LEfSe analysis revealed alterations that were similar to those described above; furthermore, different bacterial taxa were associated with MMSE scores and age. KEGG analysis showed that the functional pathways associated with the oral microbiota were mainly involved in membrane transport and carbohydrate metabolism, while the gene functions of the fecal microbiota related to metabolism of amino acids, energy, cofactors and vitamins; identified significant differences among the three groups. Venn diagram analysis revealed that the number of genera that were present in both the oral and gut microbiota increased progressively from NC to mild AD and then to moderate AD.

Conclusions

This study is the first to report a comparative analysis of the oral and fecal microbiota of patients with mild and moderate AD. The compositions and functions of the oral and gut microbiotas differed when compared between different stages of AD.

Combining fecal microbiome and metabolomics to reveal the disturbance of gut microbiota in liver injury and the therapeutic mechanism of shaoyao gancao decoction

Chemical liver injury is closely related to gut microbiota and its metabolites. In this study, we combined 16S rRNA gene sequencing, ¹H NMR-based fecal metabolomics and GC-MS to evaluate the changes in gut microbiota, fecal metabolites and Short-chain fatty acids (SCFAs) in CCl₄-induced liver injury in Sprague-Dawley rats, and the therapeutic effect of Shaoyao Gancao Decoction (SGD). The results showed that CCl₄-induced liver injury overexpressed CYP2E1, enhanced oxidative stress, decreased antioxidant enzymes (SOD, GSH), increased peroxidative products MDA and inflammatory responses (IL-6, TNF-α), which were ameliorated by SGD treatment. H&E staining showed that SGD could alleviate liver tissue lesions, which was confirmed by the recovered liver index, ALT and AST. Correlation network analysis indicated that liver injury led to a decrease in microbiota correlation, while SGD helped restore it. In addition, fecal metabolomic confirmed the PICRUSt results that liver injury caused disturbances in amino acid metabolism, which were modulated by SGD. Spearman’s analysis showed that liver injury disrupted ammonia transport, urea cycle, intestinal barrier and energy metabolism. Moreover, the levels of SCFAs were also decreased, and the abundance of Lachnoclostridium, Blautia, Lachnospiraceae_NK4A136_group, UCG-005 and Turicibacter associated with SCFAs were altered. However, all this can be alleviated by SGD. More importantly, pseudo germ-free rats demonstrated that the absence of gut microbiota aggravated liver injury and affected the efficacy of SGD. Taken together, we speculate that the gut microbiota has a protective role in the pathogenesis of liver injury, and has a positive significance for the efficacy of SGD. Moreover, SGD can treat liver injury by modulating gut microbiota and its metabolites and SCFAs. This provides useful evidence for the study of the pathogenesis of liver injury and the clinical application of SGD.

Probiotics and Gut Microbiota in Obesity: Myths and Realities of a New Health Revolution

Obesity and its comorbidities are humans’ most prevalent cardio-metabolic diseases worldwide. Recent evidence has shown that chronic low-grade inflammation is a common feature in all highly prevalent chronic degenerative diseases. In this sense, the gut microbiota is a complete ecosystem involved in different processes like vitamin synthesis, metabolism regulation, and both appetite and immune system control. Thus, dysbiosis has been recognised as one of the many factors associated with obesity due to a predominance of Firmicutes, a decrease in Bifidobacterium in the gut, and a consequent short-chain fatty acids (SCFA) synthesis reduction leading to a reduction in incretins action and intestinal permeability increase. In this context, bacteria, bacterial endotoxins, and toxic bacterial by-products are translocated to the bloodstream, leading to systemic inflammation. This review focuses on gut microbiota composition and its role in obesity, as well as probiotics and prebiotics benefits in obesity.

Therapeutic Potential of Human Microbiome-Based Short-Chain Fatty Acids and Bile Acids in Liver Disease

Microbiome-derived short chain fatty acids (SCFAs: acetate, propionate, and butyrate) and bile acids (BAs: primary BAs and secondary BAs) widely influence liver metabolic inflammation, immune responses, and carcinogenesis. In recent literature, the role of SCFAs and BAs in various liver diseases has been discussed. SCFAs and BAs are two types of microbiome-derived metabolites and they have been shown to have immunoregulatory ability in autoimmunity, inflammation, and liver-cancer microcellular environments. SCFAs and BAs are dependent on dietary components. The numerous regulatory processes in lymphocytes and non-immune cells that underpin both the positive and harmful effects of microbial metabolites include variations in metabolic signaling and epigenetic states. As a result, histone deacetylase (HDAC) inhibitors, SCFAs, and BAs, which are powerful immunometabolism modulators, have been explored. BAs have also been shown to alter the microbiome as well as adaptive and innate immune systems. We therefore emphasize the important metabolites in liver disease for clinical therapeutic applications. A deep understanding of SCFAs and Bas, as well as their molecular risk, could reveal more about certain liver-disease conditions.

Moringa oleifera Lam. Peptide Remodels Intestinal Mucosal Barrier by Inhibiting JAK-STAT Activation and Modulating Gut Microbiota in Colitis

Ulcerative colitis is a chronic inflammatory bowel disease (IBD), but progress in exploring its pathogenesis and finding effective drugs for its prevention and treatment has stalled in recent years. The seeds of Moringa oleifera Lam. are rich in proteins known to have multiple physiological activities. In our earlier work, we had isolated and purified a peptide (MOP) having the sequence KETTTIVR, from M. oleifera seeds; however, its anti-inflammatory activity and mechanism in vivo were unclear. Here we used the dextran sulfate sodium (DSS)-induced colitis model to study the anti-inflammatory activity and mechanism of this MOP. Our results are the first to show that MOP can ameliorate the pathological phenotype, inflammation, and intestinal barrier disruption in mice with colitis. Furthermore, RNA sequencing revealed that MOP inhibits the Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway activation. Next, by using 16s rRNA gene sequencing, we found that MOP can ameliorate DSS-induced gut microbiota dysbiosis. In addition, an untargeted metabolomics analysis suggested that MOP is able to modulate the level of lipid and amino acid metabolites in IBD-stricken mice. Altogether, these results indicate that MOP ameliorates colitis by remodeling intestinal mucosal barrier by inhibiting JAK-STAT pathway’s activation and regulating gut microbiota and its metabolites, thus providing a basis for further processing and design of bioactive foods from M. oleifera seeds.

[Metagenome-wide association of gut microbiome features in children with moderate-severe house dust mite allergic rhinitis]

Objective:To draw a distinct gut microbiota pattern of children with moderate-severe dust mite-induced allergic rhinitis（DAR） and healthy children. Methods:3-10 years old moderate-severe DAR children（68 cases） and healthy children（38 cases） were involved in this study. General information was collected through questionnaires, and fecal samples were collected for metagenomic sequencing. MetaPhlAn3 was used to generate the microbiota composition abundance in detail, and Alpha and Beta diversity changes were calculated. The difference in species abundance at different taxonomic levels were compared. Differences in functional pathways were compared by LEfSe analysis. Results:The diversity of gut microbiota in children with moderate-severe DAR didn't change significantly compared with healthy children. A total of 37 microbial communities or species with significant abundance difference were found, mainly included Lachnoclostridium, Prevotella, Blautia wexlerae, Prevotella copri, Eubacterium eligens, Eubacterium sp CAG 180, etc. However, the metabolism functions of gut microbiota in children with moderate-severe DAR changed compared with healthy children. Various of fatty acids anabolism enhanced in DAR children. Conclusion:Compared with healthy children, there was no significant difference in gut microbial diversity in moderate-severe DAR children. The abundance of a series of specific microbe species had a marked alteration in DAR, accompanied with changes in certain microbial functional pathways.

Models for Gut-Mediated Horizontal Gene Transfer by Bacterial Plasmid Conjugation

The emergence of new antimicrobial resistant and virulent bacterial strains may pose a threat to human and animal health. Bacterial plasmid conjugation is a significant contributor to rapid microbial evolutions that results in the emergence and spread of antimicrobial resistance (AR). The gut of animals is believed to be a potent reservoir for the spread of AR and virulence genes through the horizontal exchange of mobile genetic elements such as plasmids. The study of the plasmid transfer process in the complex gut environment is limited due to the confounding factors that affect colonization, persistence, and plasmid conjugation. Furthermore, study of plasmid transfer in the gut of humans is limited to observational studies, leading to the need to identify alternate models that provide insight into the factors regulating conjugation in the gut. This review discusses key studies on the current models for in silico, in vitro, and in vivo modeling of bacterial conjugation, and their ability to reflect the gut of animals. We particularly emphasize the use of computational and in vitro models that may approximate aspects of the gut, as well as animal models that represent in vivo conditions to a greater extent. Directions on future research studies in the field are provided.

Gut microbiome and neurocritically ill patients

Since the times of Rokitansky and Cushing, we have been fascinated by the connections between the gut and the brain. Recent advances in next-generation sequencing techniques have shown that this relationship is even more complex and integral to our sense of self than previously imagined. As these techniques refine our understanding of the abundance and diversity of the gut bacterial microbiome, the relationship between the gut and the brain has been redefined. Now, this is understood as a complex symbiotic network with bidirectional communication, the gut-brain axis. The implication of this communication involves an intense focus of research on a variety of chronic psychiatric, neurological, neurodegenerative, and neuro-oncological diseases. Recently, the gut-brain axis has been studied in neurologically ill patients requiring intensive care. Preliminary studies have shown that acute brain injury changes the bacterial phenotype from one that is symbiotic with the host human to one that is pathologic, termed the “pathobiome.” This can contribute to nosocomial pneumonia and sepsis. The first studies in neurologically ill patients in the neurointensive care unit (NeuroICU) demonstrated changes in the gut microbiome between neuroICU patients and healthy matched subjects. Specifically, a decrease in short-chain fatty acid-producing bacteria and increase in harmful gut microbes have been associated with mortality and decreased function at discharge. Although these preliminary findings are exciting and have opened a new field of research in the complex NeuroICU population, there are several limitations and challenges. Further investigation is needed to confirm these correlations and understand their implications on patients in a complex intensive care environment.

Metabolomics: The Key to Unraveling the Role of the Microbiome in Visceral Pain Neurotransmission

Inflammatory bowel disease (IBD), comprising Crohn's disease and Ulcerative colitis, is a relapsing and remitting disease of the gastrointestinal tract, presenting with chronic inflammation, ulceration, gastrointestinal bleeding, and abdominal pain. Up to 80% of patients suffering from IBD experience acute pain, which dissipates when the underlying inflammation and tissue damage resolves. However, despite achieving endoscopic remission with no signs of ongoing intestinal inflammation or damage, 30-50% of IBD patients in remission experience chronic abdominal pain, suggesting altered sensory neuronal processing in this disorder. Furthermore, effective treatment for chronic pain is limited such that 5-25% of IBD outpatients are treated with narcotics, with associated morbidity and mortality. IBD patients commonly present with substantial alterations to the microbial community structure within the gastrointestinal tract, known as dysbiosis. The same is also true in irritable bowel syndrome (IBS), a chronic disorder characterized by altered bowel habits and abdominal pain, in the absence of inflammation. An emerging body of literature suggests that the gut microbiome plays an important role in visceral hypersensitivity. Specific microbial metabolites have an intimate relationship with host receptors that are highly expressed on host cell and neurons, suggesting that microbial metabolites play a key role in visceral hypersensitivity. In this review, we will discuss the techniques used to analysis the metabolome, current potential metabolite targets for visceral hypersensitivity, and discuss the current literature that evaluates the role of the post-inflammatory microbiota and metabolites in visceral hypersensitivity.

Gut Microbiome Differences in Rescued Common Kestrels (Falco tinnunculus) Before and After Captivity

Gut microbes significantly impact animal health, yet research on the gut microbiota of most birds, especially raptors, is lacking. This study investigated the effects of dietary and environmental changes on the composition and abundance of gut microbiota in 17 rescued common kestrels (Falco tinnunculus) through 16S rRNA gene high-throughput sequencing of microorganisms in the feces of the birds. Firmicutes (relative abundance, 43.63%), Proteobacteria (37.26%), Actinobacteria (7.31%), and Bacteroidetes (5.48%) were the dominant phyla in the gut microbiota of the common kestrels. A comparison of the gut microbiota before and after captivity revealed that community composition and abundance of the common kestrel gut microbiota differed among different living conditions including diet and environment. At the phylum level, the abundance of Firmicutes was higher (P < 0.05), and that of Proteobacteria was lower (P < 0.05), after captivity (54.62 and 27.16%, respectively) compared with before captivity (33.67 and 46.41%, respectively), but no significant differences were found among other phyla. At the genus level, the abundance of Lactobacillus was higher (P < 0.05) after captivity (15.77%) compared with the abundance before captivity (5.02%). Hierarchical clustering and principal component analyses showed that common kestrels in different living conditions exhibited differences (P < 0.05) in gut microbiota at phylum and genus levels. Functional prediction of gene sequences using PICRUSt2 further revealed that pathways related to glucose metabolism and amino acid metabolism were enhanced (P < 0.05) after captivity. Collectively, the findings from this study demonstrated that the relative abundance of specific microbes in the gut of the rescued common kestrels either increased or decreased, and that dietary and environment changes might be the predominant factors affecting the gut microbiota of these birds during rescue or captivity.

Gut dysbiosis promotes prostate cancer progression and docetaxel resistance via activating NF-κB-IL6-STAT3 axis

BACKGROUND

The gut microbiota is reportedly involved in the progression and chemoresistance of various human malignancies. However, the underlying mechanisms behind how it exerts some effect on prostate cancer, as an extra-intestinal tumor, in a contact-independent way remain elusive and deserve exploration. Antibiotic exposure, one of the various factors affecting the gut microbiota community and capable of causing gut dysbiosis, is associated with multiple disorders. This study aims to preliminarily clarify the link between gut dysbiosis and prostate cancer.

RESULTS

First, we discovered that perturbing the gut microbiota by consuming broad-spectrum antibiotics in water promoted the growth of subcutaneous and orthotopic tumors in mice. Fecal microbiota transplantation could transmit the effect of antibiotic exposure on tumor growth. Then, 16S rRNA sequencing for mouse feces indicated that the relative abundance of Proteobacteria was significantly higher after antibiotic exposure. Meanwhile, intratumoral lipopolysaccharide (LPS) profoundly increased under the elevation of gut permeability. Both in vivo and in vitro experiments revealed that the NF-κB-IL6-STAT3 axis activated by intratumoral LPS facilitated prostate cancer proliferation and docetaxel chemoresistance. Finally, 16S rRNA sequencing of patients' fecal samples revealed that Proteobacteria was enriched in patients with metastatic prostate cancer and was positively correlated with plasma IL6 level, regional lymph node metastasis status, and distant metastasis status. The receiver operating characteristic (ROC) curves showed that the relative abundance of Proteobacteria had better performance than the prostate-specific antigen (PSA) level in predicting the probability of distant metastasis in prostate cancer (area under the ROC curve, 0.860; p < 0.001).

CONCLUSION

Collectively, this research demonstrated that gut dysbiosis, characterized by the enrichment of Proteobacteria due to antibiotic exposure, resulted in the elevation of gut permeability and intratumoral LPS, promoting the development of prostate cancer via the NF-κB-IL6-STAT3 axis in mice. Considering findings from human patients, Proteobacteria might act as an intestinal biomarker for progressive prostate cancer. Video Abstract.

Influence of dietary supplementation of short-chain fatty acid sodium propionate in people living with HIV (PLHIV)

BACKGROUND

Non-AIDS-associated chronic diseases in HIV+ patients have been on the rise since the advent of antiretroviral therapy. Especially cardiovascular diseases and disruption in the gastrointestinal tract have limited health-related quality of life (QoL). Several of those complications have been associated with chronic systemic inflammation. Short-chain fatty acids (SCFA), with propionate as one of the major compounds, have been described as an important link between gut microbiota and the immune system, defining the pro- and the anti-inflammatory milieu through direct and indirect regulation of T-cell homeostasis. The effects of dietary supplementation of sodium propionate (SP) in people living with HIV (PLHIV) have not yet been investigated prior to this study.

OBJECTIVES

To investigate the impact of SP uptake among PLHIV and its relevance to improve QoL, the study aimed to investigate metabolic, immunological, microbiome and patient-reported QoL-related changes post-SP supplementation with follow-up.

METHODS

A prospective, non-randomized, controlled, monocentric interventional study was conducted in WIR, Center for Sexual Health and Medicine, in Bochum, Germany. 32 HIV+ patients with unaltered ART-regimen in the last three months were included. Participants were given SP for a duration of 12 weeks in the form of daily oral supplementation and were additionally followed-up for another 12 weeks.

RESULTS

The supplementation of SP was well tolerated. We found an improvement in lipid profiles and long-term blood glucose levels. A decrease in pro-inflammatory cytokines and a depletion of effector T cells was observed. Regulatory T cells and IL-10 decreased. Furthermore, changes in taxonomic composition of the microbiome during follow-up were observed and improvement of items of self-reported life-quality assessment.

CONCLUSION

Taken together, the beneficial impact of SP in PLHIV reflects its potential in improving metabolic parameters and modulating pro-inflammatory immune responses. Thus, possibly reducing the risk of cardiovascular disorders and facilitating long-term improvement of the gut flora.

Probiotic supplementation: A prospective approach in the treatment of COVID-19

Background: Despite strategies based on social distancing, the coronavirus disease 2019 (COVID-19) expands globally, and so far, many attempts have been made to achieve effective treatment for patients with COVID-19. This disease infects the lower respiratory tract and may lead to severe acute respiratory syndrome coronavirus (SARS-CoV). COVID-19 also can cause gastrointestinal infections. Therefore, COVID-19 patients with gastrointestinal symptoms are more likely to be complicated by SARS-CoV. In this disease, acquired immune responses are impaired, and uncontrolled inflammatory responses result in cytokine storms, leading to acute lung injury and thrombus formation. Probiotics are living microorganisms that contribute to the health of the host if administered in appropriate doses. Aim: This study aimed to provide evidence to show the importance of gut dysbiosis in viral disease, especially COVID-19. Therefore, we have focused on the impact of probiotics consumption on preventing severe symptoms of the disease. Methods: We have entirely searched SCOPUS, PubMed, and Google Scholar databases to collect evidence regarding the relationship between probiotics and viral infections to expand this relationship to the COVID-19. Results: It has been shown that probiotics directly counteract SARS-CoV in the gastrointestinal and respiratory tracts. Moreover, probiotics suppress severe immune responses and prevent cytokine storms to inhibit pathologic inflammatory conditions in the body via modulation of immune responses. Conclusion: According to available evidence based on their antiviral and respiratory activities, using probiotics might be an adjuvant therapy to reduce the burden and severity of this disease.

Abnormal Epigenetic Regulations in the Immunocytes of Sjögren's Syndrome Patients and Therapeutic Potentials

Sjögren's syndrome (SjS), characterized by keratoconjunctivitis sicca and dry mouth, is a common autoimmune disease, especially in middle-aged women. The immunopathogenesis of SjS is caused by the sequential infiltration of T and B cells into exocrine glands, including salivary and lacrimal glands. Effector cytokines produced by these immunocytes, such as interferons (IFNs), IL-17, IL-22, IL-21, IL-4, TNF-α, BAFF and APRIL, play critical roles in promoting autoimmune responses and inducing tissue damages. Epigenetic regulations, including DNA methylation, histone modification and non-coding RNAs, have recently been comprehensively studied during the activation of various immunocytes. The deficiency of key epigenetic enzymes usually leads to aberrant immune activation. Epigenetic modifications in T and B cells are usually found to be altered during the immunopathogenesis of SjS, and they are closely correlated with autoimmune responses. In particular, the important role of methylation in activating IFN pathways during SjS progression has been revealed. Thus, according to the involvement of epigenetic regulations in SjS, target therapies to reverse the altered epigenetic modifications in auto-responsive T and B cells are worthy of being considered as a potential therapeutic strategy for SjS.

Gancao Xiexin Decoction Ameliorates Ulcerative Colitis in Mice via Modulating Gut Microbiota and Metabolites

Purpose

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that starts with mucosal inflammation of the rectum and extends proximally in the colon in a continuous manner over a variable distance. Although it is more common in North America and Western Europe, its incidence is also increasing in Asia. Despite the introduction of several different classes of medications, the treatment options for UC may be insufficiently effective and burdened with significant side effects. In the present study, the therapeutic effects of Gancao Xiexin decoction (GCXX) were investigated on mice with dextran sulfate sodium (DSS)-induced colitis with exploration of the underlying mechanisms.

Methods

Colitis was induced in C57BL/6 mice by administering 3% DSS in drinking water for 7 days. GCXX and (or) the standard of care anti-inflammatory drug, mesalazine (5-aminosalicylic acid) were then administered for 7 days. The gut microbiota was characterized by 16S rDNA high-throughput gene sequencing and gut metabolites were detected by untargeted metabolomics. Germ-free mice were subsequently used to determine whether GCXX ameliorated UC principally through modulation of the gut microbiota.

Results

GCXX treatment was demonstrated to significantly reduce disease activity index (DAI) scores, prevent colonic shortening, ameliorate colonic tissue damage and reduce the levels of pro-inflammatory cytokines. Furthermore, analysis of the gut microbiota showed that GCXX-treated mice had higher relative quantity of Dubosiella (P<0.05) and lower relative quantity of Escherichia-Shigella (P<0.05). Metabolomics analysis indicated that GCXX could reduce the level of linoleic acid (P<0.05) and regulate its metabolism pathway. Moreover, in germ-free mice, GCXX failed to increase body weight, reduce DAI scores, or alleviate either colonic shortening or colonic damage.

Conclusion

The present study demonstrated that GCXX ameliorated DSS-induced colitis principally through modulating the gut microbiota and metabolites. This information should be integrated into the overall mechanisms of GCXX treatment of UC.

Lessons to Learn from the Gut Microbiota: A Focus on Amyotrophic Lateral Sclerosis

The gut microbiota is able to modulate the development and homeostasis of the central nervous system (CNS) through the immune, circulatory, and neuronal systems. In turn, the CNS influences the gut microbiota through stress responses and at the level of the endocrine system. This bidirectional communication forms the “gut microbiota–brain axis” and has been postulated to play a role in the etiopathology of several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Numerous studies in animal models of ALS and in patients have highlighted the close communication between the immune system and the gut microbiota and, therefore, it is possible that alterations in the gut microbiota may have a direct impact on neuronal function and survival in ALS patients. Consequently, if the gut dysbiosis does indeed play a role in ALS-related neurodegeneration, nutritional immunomodulatory interventions based on probiotics, prebiotics, and/or postbiotics could emerge as innovative therapeutic strategies. This review aimed to shed light on the impact of the gut microbiota in ALS disease and on the use of potential nutritional interventions based on different types of biotics to ameliorate ALS symptoms.

The effects of dietary fiber on common complications in critically ill patients; with a special focus on viral infections; a systematic reveiw

Background

Viral infections are mostly highly contagious and may cause widespread health problems. Some studies reported that the dietary fiber (DF) may be effective in reducing the complications of viral infections in intensive care unit (ICU) patients. The present review study aimed to investigate the effect of DF on common complications in critically ill patients with viral infections.

Methods

A literature review was conducted for the published papers in English from January 2001 to July 2021 using related keywords. Studies with clinical trial or case‐control design described the effects of fiber intake on the complications of viral infections in patients admitted to the ICU were collected.

Results

DF may reduce the mortality rate of viral infections through modulating inflammatory processes. A higher intake of DF intake may improve hyperglycemia and impaired glucose tolerance in patients with viral infections. A high‐fiber formula in enteral nutrition was reported to reduce the risk of diarrhea in patients with viral infections.

Conclusion

DF may reduce the complications of viral infections such as inflammation, diarrhea, hyperglycemia, and mortality in critically ill patients. Future longitudinal studies on the amount and type of DF are warranted.

Bacterial driver-passenger model in biofilms: a new mechanism in the development of colorectal cancer

Colorectal cancer (CRC) is a heterogeneous disease of the intestinal epithelium and ranks the third largest diagnosed malignancy in the world. Many studies have shown that the high risk of CRC is believed to be related to the formation of biofilms. To prove causation, it will be significant to decipher which specific bacteria in biofilms initiate and maintain CRC and fully describe their underlying mechanisms. Here we introduce a bacterial driver-passenger model. This model added a novel and compelling angle to the role of microorganisms, putting more emphasis on the transformation of bacterial composition in biofilms which play different roles in the development of CRC. In this model, bacterial drivers can initiate the formation of CRC through genotoxicity, while bacterial passengers maintain the CRC process through metabolites. On the basis of these pathogens, we further turned our attention to strategies that can inhibit and eradicate these pathogenic biofilms, with the aim of finding new ways to hinder colorectal carcinogenesis.

Glioma and the Gut-Brain Axis: Opportunities and Future Perspectives

The gut–brain axis has presented a valuable new dynamic in the treatment of cancer and central nervous system (CNS) diseases. However, little is known about the potential role of this axis in neuro-oncology. The goal of this review is to highlight potential implications of the gut–brain axis in neuro-oncology, in particular gliomas, and future areas of research. The gut–brain axis is a well-established biochemical signaling axis that has been associated with various CNS diseases. In neuro-oncology, recent studies have described gut microbiome differences in tumor-bearing mice and glioma patients compared to controls. These differences in the composition of the microbiome are expected to impact the metabolic functionality of each microbiome. The effects of antibiotics on the microbiome may affect tumor growth and modulate the immune system in tumor-bearing mice. Preliminary studies have shown that the gut microbiome might influence PD-L1 response in glioma-bearing mice, as previously observed in other non-CNS cancers. Groundbreaking studies have identified intratumoral bacterial DNA in several cancers including high-grade glioma. The gut microbiome and its manipulation represent a new and relatively unexplored area that could be utilized to enhance the effectiveness of therapy in glioma. Further mechanistic studies of this therapeutic strategy are needed to assess its clinical relevance.

Exploring the Gut Microbiome in Myasthenia Gravis

The human gut microbiota is vital for maintaining human health in terms of immune system homeostasis. Perturbations in the composition and function of microbiota have been associated with several autoimmune disorders, including myasthenia gravis (MG), a neuromuscular condition associated with varying weakness and rapid fatigue of the skeletal muscles triggered by the host’s antibodies against the acetylcholine receptor (AChR) in the postsynaptic muscle membrane at the neuromuscular junction (NMJ). It is hypothesized that perturbation of the gut microbiota is associated with the pathogenesis of MG. The gut microbiota community profiles are usually generated using 16S rRNA gene sequencing. Compared to healthy individuals, MG participants had an altered gut microbiota’s relative abundance of bacterial taxa, particularly with a drop in Clostridium. The microbial diversity related to MG severity and the overall fecal short-chain fatty acids (SCFAs) were lower in MG subjects. Changes were also found in terms of serum biomarkers and fecal metabolites. A link was found between the bacterial Operational Taxonomic Unit (OTU), some metabolite biomarkers, and MG’s clinical symptoms. There were also variations in microbial and metabolic markers, which, in combination, could be used as an MG diagnostic tool, and interventions via fecal microbiota transplant (FMT) could affect MG development. Probiotics may influence MG by restoring the gut microbiome imbalance, aiding the prevention of MG, and lowering the risk of gut inflammation by normalizing serum biomarkers. Hence, this review will discuss how alterations of gut microbiome composition and function relate to MG and the benefits of gut modulation.

Tryptophan Supplementation Increases the Production of Microbial-Derived AhR Agonists in an In Vitro Simulator of Intestinal Microbial Ecosystem

The aryl hydrocarbon receptor (AhR) plays an important role in intestinal homeostasis, and some microbial metabolites of tryptophan are known AhR agonists. In this study, we assessed the impact of tryptophan supplementation on the formation of tryptophan metabolites, AhR activation, and microbiota composition in the simulator of the human intestinal microbial ecosystem (SHIME). AhR activation, microbial composition, and tryptophan metabolites were compared during high tryptophan supplementation (4 g/L tryptophan), control, and wash-out periods. During tryptophan supplementation, the concentration of several tryptophan metabolites was increased compared to the control and wash-out period, but AhR activation by fermenter supernatant was significantly decreased. This was due to the higher levels of tryptophan, which was found to be an antagonist of AhR signaling. Tryptophan supplementation induced most microbial changes in the transverse colon including increased relative abundance of lactobacillus. We conclude that tryptophan supplementation leads to increased formation of AhR agonists in the colon.

Gut microbiota drives macrophage-dependent self-renewal of intestinal stem cells via niche enteric serotonergic neurons

Lgr5⁺ intestinal stem cells (ISCs) reside within specialized niches at the crypt base and harbor self-renewal and differentiation capacities. ISCs in the crypt base are sustained by their surrounding niche for precise modulation of self-renewal and differentiation. However, how intestinal cells in the crypt niche and microbiota in enteric cavity coordinately regulate ISC stemness remains unclear. Here, we show that ISCs are regulated by microbiota and niche enteric serotonergic neurons. The gut microbiota metabolite valeric acid promotes Tph2 expression in enteric serotonergic neurons via blocking the recruitment of the NuRD complex onto Tph2 promoter. 5-hydroxytryptamine (5-HT) in turn activates PGE2 production in a PGE2⁺ macrophage subset through its receptors HTR2A/3 A; and PGE2 via binding its receptors EP1/EP4, promotes Wnt/β-catenin signaling in ISCs to promote their self-renewal. Our findings illustrate a complex crosstalk among microbiota, intestinal nerve cells, intestinal immune cells and ISCs, revealing a new layer of ISC regulation by niche cells and microbiota.

Understanding the Complexities and Changes of the Astronaut Microbiome for Successful Long-Duration Space Missions

During space missions, astronauts are faced with a variety of challenges that are unique to spaceflight and that have been known to cause physiological changes in humans over a period of time. Several of these changes occur at the microbiome level, a complex ensemble of microbial communities residing in various anatomic sites of the human body, with a pivotal role in regulating the health and behavior of the host. The microbiome is essential for day-to-day physiological activities, and alterations in microbiome composition and function have been linked to various human diseases. For these reasons, understanding the impact of spaceflight and space conditions on the microbiome of astronauts is important to assess significant health risks that can emerge during long-term missions and to develop countermeasures. Here, we review various conditions that are caused by long-term space exploration and discuss the role of the microbiome in promoting or ameliorating these conditions, as well as space-related factors that impact microbiome composition. The topics explored pertain to microgravity, radiation, immunity, bone health, cognitive function, gender differences and pharmacomicrobiomics. Connections are made between the trifecta of spaceflight, the host and the microbiome, and the significance of these interactions for successful long-term space missions.

Differential Effects of the Soluble Fiber Inulin in Reducing Adiposity and Altering Gut Microbiome in Aging Mice

Inulin, a soluble dietary fiber, is thought to exert multiple beneficiary effects through promoting growth of bacteria that metabolize the fiber to short-chain fatty acids (SCFAs); however, the effect and efficacy of inulin in aging subjects is unknown. This study aims to systematically evaluate the capacity of SCFAs production and host response in mice of different ages. Male C57BL/6J mice across young (5 months), middle (11 months) and old (26 months) age were subjected to a control diet for two weeks, followed by 6 weeks of inulin-containing diet. Inulin-induced increase in fecal butyric acid levels was most prominent in middle-age group compared to other age groups. In addition, inulin-induced increase in fecal propionic acids showed age-dependent decline. Interestingly, the SCFA-producing Roseburia was most abundantly and persistently increased in the middle-age group. Furthermore, inulin intake significantly reduced Firmicutes to Bacteroidetes ratio, and several dysbiotic bacteria associated with pro-inflammatory state. Concomitantly, circulating levels of CXCL1, a chemoattractant for neutrophils, was reduced by inulin intake. Inulin decreased fat mass in all age groups, with middle-aged mice being most responsive to fat-reducing effects of inulin. Moreover, inulin significantly increased energy expenditure and voluntary wheel running in middle-aged mice, but not in old mice. Overall, our data suggest that the efficacy of inulin in altering the microbiome and SCFA production, and the subsequent metabolic response was diminished in old mice, and highlight the importance of including age as a variable in studies determining host-microbe response to diets.

High-Salt Diet Induces Depletion of Lactic Acid-Producing Bacteria in Murine Gut

Dietary habits are amongst the main factors that influence the gut microbiome. Accumulating evidence points to the impact of a high-salt diet (HSD) on the composition and function of the intestinal microbiota, immune system and disease. In the present study, we thus investigated the effects of different NaCl content in the food (0.03%/sodium deficient, 0.5%/control, 4% and 10% NaCl) on the gut microbiome composition in mice. The bacterial composition was profiled using the 16S ribosomal RNA (rRNA) gene amplicon sequencing. Our results revealed that HSD led to distinct gut microbiome compositions compared to sodium-deficient or control diets. We also observed significant reduction in relative abundances of bacteria associated with immuno-competent short-chain fatty acid (SCFA) production (Bifidobacterium, Faecalibaculum, Blautia and Lactobacillus) in HSD-fed mice along with significant enrichment of Clostridia, Alistipes and Akkermansia depending on the sodium content in food. Furthermore, the predictive functional profiling of microbial communities indicated that the gut microbiota found in each category presents differences in metabolic pathways related to carbohydrate, lipid and amino acid metabolism. The presented data show that HSD cause disturbances in the ecological balance of the gastrointestinal microflora primarily through depletion of lactic acid-producing bacteria in a dose-dependent manner. These findings may have important implications for salt-sensitive inflammatory diseases.

Homeostasis and Cancer Initiation: Organoids as Models to Study the Initiation of Gastric Cancer

Gastric cancer represents a significant disease burden worldwide. The factors that initiate cancer are not well understood. Chronic inflammation such as that triggered by H. pylori infection is the most significant cause of gastric cancer. In recent years, organoid cultures developed from human and animal adult stem cells have facilitated great advances in our understanding of gastric homeostasis. Organoid models are now being exploited to investigate the role of host genetics and bacterial factors on proliferation and DNA damage in gastric stem cells. The impact of a chronic inflammatory state on gastric stem cells and the stroma has been less well addressed. This review discusses what we have learned from the use of organoid models to investigate cancer initiation, and highlights questions on the contribution of the microbiota, chronic inflammatory milieu, and stromal cells that can now be addressed by more complex coculture models.

The Nutrition-Microbiota-Physical Activity Triad: An Inspiring New Concept for Health and Sports Performance

The human gut microbiota is currently the focus of converging interest in many diseases and sports performance. This review presents gut microbiota as a real “orchestra conductor” in the host’s physio(patho)logy due to its implications in many aspects of health and disease. Reciprocally, gut microbiota composition and activity are influenced by many different factors, such as diet and physical activity. Literature data have shown that macro- and micro-nutrients influence gut microbiota composition. Cumulative data indicate that gut bacteria are sensitive to modulation by physical activity, as shown by studies using training and hypoactivity models. Sports performance studies have also presented interesting and promising results. Therefore, gut microbiota could be considered a “pivotal” organ for health and sports performance, leading to a new concept: the nutrition-microbiota-physical activity triad. The next challenge for the scientific and medical communities is to test this concept in clinical studies. The long-term aim is to find the best combination of the three elements of this triad to optimize treatments, delay disease onset, or enhance sports performance. The many possibilities offered by biotic supplementation and training modalities open different avenues for future research.

Human Fecal Microbiota Transplantation Reduces the Susceptibility to Dextran Sulfate Sodium-Induced Germ-Free Mouse Colitis

In clinical practice, fecal microbiota transplantation (FMT) has been used to treat inflammatory bowel disease (IBD), and has shown certain effects. However, the selection of FMT donors and the mechanism underlying the effect of FMT intervention in IBD require further exploration. In this study, dextran sodium sulfate (DSS)-induced colitis mice were used to determine the differences in the protection of colitis symptoms, inflammation, and intestinal barrier, by FMT from two donors. Intriguingly, pre-administration of healthy bacterial fluid significantly relieved the symptoms of colitis compared to the ulcerative colitis (UC) bacteria. In addition, healthy donor (HD) bacteria significantly reduced the levels of inflammatory markers Myeloperoxidase (MPO) and Eosinophil peroxidase (EPO), and various pro-inflammatory factors, in colitis mice, and increased the secretion of the anti-inflammatory factor IL-10. Metagenomic sequencing indicated higher species diversity and higher abundance of anti-inflammatory bacteria in the HD intervention group, including Alistipes putredinis, Akkermansia muciniphila, Bifidobacterium adolescentis, short-chain fatty acids (SCFAs)-producing bacterium Christensenella minuta, and secondary bile acids (SBAs)-producing bacterium Clostridium leptum. In the UC intervention group, the SCFA-producing bacterium Bacteroides stercoris, IBD-related bacterium Ruminococcus gnavus, Enterococcus faecalis, and the conditional pathogen Bacteroides caccae, were more abundant. Metabolomics analysis showed that the two types of FMT significantly modulated the metabolism of DSS-induced mice. Moreover, compared with the UC intervention group, indoleacetic acid and unsaturated fatty acids (DHA, DPA, and EPA) with anti-inflammatory effects were significantly enriched in the HD intervention group. In summary, these results indicate that FMT can alleviate the symptoms of colitis, and the effect of HD intervention is better than that of UC intervention. This study offers new insights into the mechanisms of FMT clinical intervention in IBD.

Effects of viremia and CD4 recovery on gut "microbiome-immunity" axis in treatment-naïve HIV-1-infected patients undergoing antiretroviral therapy

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) infection is characterized by persistent systemic inflammation and immune activation, even in patients receiving effective antiretroviral therapy (ART). Converging data from many cross-sectional studies suggest that gut microbiota (GM) changes can occur throughout including human immunodeficiency virus (HIV) infection, treated by ART; however, the results are contrasting. For the first time, we compared the fecal microbial composition, serum and fecal microbial metabolites, and serum cytokine profile of treatment-naïve patients before starting ART and after reaching virological suppression, after 24 wk of ART therapy. In addition, we compared the microbiota composition, microbial metabolites, and cytokine profile of patients with CD4/CD8 ratio < 1 (immunological non-responders [INRs]) and CD4/CD8 > 1 (immunological responders [IRs]), after 24 wk of ART therapy.

AIM

To compare for the first time the fecal microbial composition, serum and fecal microbial metabolites, and serum cytokine profile of treatment-naïve patients before starting ART and after reaching virological suppression (HIV RNA < 50 copies/mL) after 24 wk of ART.

METHODS

We enrolled 12 treatment-naïve HIV-infected patients receiving ART (mainly based on integrase inhibitors). Fecal microbiota composition was assessed through next generation sequencing. In addition, a comprehensive analysis of a blood broad-spectrum cytokine panel was performed through a multiplex approach. At the same time, serum free fatty acid (FFA) and fecal short chain fatty acid levels were obtained through gas chromatography-mass spectrometry.

RESULTS

We first compared microbiota signatures, FFA levels, and cytokine profile before starting ART and after reaching virological suppression. Modest alterations were observed in microbiota composition, in particular in the viral suppression condition, we detected an increase of Ruminococcus and Succinivibrio and a decrease of Intestinibacter. Moreover, in the same condition, we also observed augmented levels of serum propionic and butyric acids. Contemporarily, a reduction of serum IP-10 and an increase of IL-8 levels were detected in the viral suppression condition. In addition, the same components were compared between IRs and INRs. Concerning the microflora population, we detected a reduction of Faecalibacterium and an increase of Alistipes in INRs. Simultaneously, fecal isobutyric, isovaleric, and 2-methylbutyric acids were also increased in INRs.

CONCLUSION

Our results provided an additional perspective about the impact of HIV infection, ART, and immune recovery on the "microbiome-immunity axis" at the metabolism level. These factors can act as indicators of the active processes occurring in the gastrointestinal tract. Individuals with HIV-1 infection, before ART and after reaching virological suppression with 24 wk of ART, displayed a microbiota with unchanged overall bacterial diversity; moreover, their systemic inflammatory status seems not to be completely restored. In addition, we confirmed the role of the GM metabolites in immune reconstitution.