Research advances of vasoactive intestinal peptide in the pathogenesis of ulcerative colitis by regulating interleukin-10 expression in regulatory B cells

Ulcerative colitis (UC) is a chronic relapsed intestinal disease with an increasing incidence around the world. The pathophysiology of UC remains unclear. However, the role of the interaction between the enteric nervous system and the immune system in the pathogenesis of UC has been the focus of attention and has become a research hotspot. Vasoactive intestinal peptide (VIP) is a kind of endogenous neuropeptide with regulatory activity on intestinal immunity. It has been shown to regulate immune disorders in animal and human experiments and has become an effective anti-inflammatory and immune modulator that affects the innate immune system and adaptive immune system. Regulatory B cells (Bregs) are a new group of B cells that negatively regulate the immunity and have received extensive attention in immune circles. Bregs can regulate immune tolerance by producing interleukin (IL)-10, IL-35, and transforming growth factor-β, suppressing autoimmune diseases or excessive inflammatory responses. The secretion of IL-10 by Bregs induces the development of T helper (Th) 0 and Th2 cells. It also induces Th2 cytokines and inhibits Th1 cytokines, thereby inhibiting Th1 cells and the Th1/Th2 balance. With further clarity on the mechanism of the regulation of IL-10 expression by VIP in Bregs in colitis patients, we believe that Bregs can provide a novel strategy for the clinical treatment of UC. Thus, we aim to review the current literature on this evolving topic.

Nutraceutical Strategies for Suppressing NLRP3 Inflammasome Activation: Pertinence to the Management of COVID-19 and Beyond

Inflammasomes are intracellular protein complexes that form in response to a variety of stress signals and that serve to catalyze the proteolytic conversion of pro-interleukin-1β and pro-interleukin-18 to active interleukin-1β and interleukin-18, central mediators of the inflammatory response; inflammasomes can also promote a type of cell death known as pyroptosis. The NLRP3 inflammasome has received the most study and plays an important pathogenic role in a vast range of pathologies associated with inflammation-including atherosclerosis, myocardial infarction, the complications of diabetes, neurological and autoimmune disorders, dry macular degeneration, gout, and the cytokine storm phase of COVID-19. A consideration of the molecular biology underlying inflammasome priming and activation enables the prediction that a range of nutraceuticals may have clinical potential for suppressing inflammasome activity-antioxidants including phycocyanobilin, phase 2 inducers, melatonin, and N-acetylcysteine, the AMPK activator berberine, glucosamine, zinc, and various nutraceuticals that support generation of hydrogen sulfide. Complex nutraceuticals or functional foods featuring a number of these agents may find utility in the prevention and control of a wide range of medical disorders.

Undaria pinnatifida improves obesity-related outcomes in association with gut microbiota and metabolomics modulation in high-fat diet-fed mice

Dietary fiber has beneficial effects on obesity-related diseases and gut microbiota, contributing a key role in the interaction between dietary metabolism and host metabolism. Our objective was to investigate the cause of the improvement in multiple types of physiological states with seaweed Undaria pinnatifida treatment on high-fat diet-fed mice and to evaluate whether its consequent anti-adiposity and anti-hyperlipidemic effects are associated with gut microbiota and its metabolomics regulation. U. pinnatifida administration in our experiment was shown to significantly decrease high-fat diet-induced body weight gain, as well as epididymal and abdominal adiposity. U. pinnatifida intake also significantly reduced liver weight and serum triacylglycerol accumulation. We also found that improving effects of U. pinnatifida on high-fat diet-induced metabolic dysfunctions were associated with significant increase in specific bacteria, such as Bacteroides acidifaciens and Bacteroides ovatus, as well as metabolites, including short-chain fatty acids and tricarboxylic acid cycle intermediates. Our result provides a cheap dietary strategy to host metabolism improvement and obesity management. KEY POINTS: • U. pinnatifida improved adipose accumulation and lipid metabolism. • B. acidifaciens and B. ovatus contributed to the beneficial effects of U. pinnatifida. • SCFAs and TCA cycle intermediates were critical to the metabolic outcomes. • Our study provides a cheap dietary strategy for obesity management.

Inulin Exerts Beneficial Effects on Non-Alcoholic Fatty Liver Disease via Modulating gut Microbiome and Suppressing the Lipopolysaccharide-Toll-Like Receptor 4-Mψ-Nuclear Factor-κB-Nod-Like Receptor Protein 3 Pathway via gut-Liver Axis in Mice

Background: Non-alcoholic fatty liver disease (NAFLD) is a common metabolic disease worldwide with chronic low-grade inflammation and alteration of gut microbiota. Inulin (INU) has been confirmed to exhibit benefit for metabolic diseases. The aim of this study was to clarify the effects and mechanism of INU on NAFLD inflammation via gut-liver axis.

Methods: C57BL/6 mice were randomly divided into four groups: normal diet group (ND); high-fat diet group (HFD); ND with INU group (ND-INU); HFD with INU group (HFD-INU). After 14 weeks of feeding, mice were sacrificed and associated indications were investigated.

Results: Significant increases of body weight, liver weight, liver biochemical aspartate aminotransferase, alanine aminotransferase, triglyceride, total cholesterol and pro-inflammatory indicators (Lipopolysaccharide, interleukin (IL)-18, IL-1β, TNF-α and IL-6), as well as a reduction of plasma IL-10 were observed in HFD group, while INU treatment restored these abnormal indicators. The ratio of hepatic macrophages (Mψs) and Toll-like receptor 4⁺ Mψs were both reduced with INU intervention. Nuclear factor-κB, nod-like receptor protein 3, apoptosis-associated speck-like protein and caspase-1 were decreased in HFD-INU group. Additionally, the results of 16S rRNA sequencing and analysis showed that INU administration modulated the composition of gut microbial community in NAFLD mice by up-regulating the abundances of Akkermansia and Bifidobacterium as well as down-regulating the abundances of Blautia and the ratio of Firmicutes/Bacteroidetes. Short-chain fatty acids including acetic acid, propionic acid and butyric acid, were increased with INU treatment. Correlation analysis revealed close relationships among inflammatory indicators, metabolic indicators as well as gut microbiota/its metabolite short-chain fatty acids.

Conclusion: INU prevents NAFLD via modulating gut microbiota and suppressing Lipopolysaccharide-Toll-like receptor 4-Mψ-Nuclear factor-κB-nod-like receptor protein 3 inflammatory pathway via the gut-liver axis.

Effects of grazing mixed-grass pastures on growth performance, immune responses, and intestinal microbiota in free-range Beijing-you chickens

There is an increasing interest in free-range poultry with the increasing focus on food safety and animal welfare. This study was conducted to evaluate the effects of grazing mixed-grass pastures on growth performance, immune responses, and intestinal microbiota in free-range laying chickens. Ten-week-old female Beijing-you chickens were blocked by the BW and randomly assigned to 3 free-range systems in poplar plantations for 120 d: forage-removed paddocks with a high stocking density of 5 m²/hen (control [CK]); mixed-grass pastures with a low stocking density of 6 m²/hen ;or mixed-grass pastures with a high stocking density of 5 m²/hen. Intestinal microbial community analysis was performed by 16S rRNA gene sequencing using Illumina MiSeq. The results revealed that no differences (P > 0.05) were found between the 3 raising systems for the BW and ADG. Chickens grazing mixed-grass pastures exhibited decreased (P > 0.05) mortality and improved immune responses as evidenced by increased T-lymphocyte proliferation (P > 0.05) and immunoglobulin A (P > 0.05) and immunoglobulin M concentrations (P < 0.05) compared with those raised in forage-removed paddocks. Metagenomic analysis indicated that grazing mixed-grass pastures regulated the intestinal microbiota by increasing the prevalence of beneficial bacteria, such as Lactobacillus, Bacteroides, and Faecalibacterium, and reducing potentially pathogenic bacteria population, such as the Rikenellaceae_RC9_gut_group compared with the CK. Therefore, this study indicated that grazing mixed-grass pastures could positively influence intestinal microbiota that may contribute to the overall growth and immunity of free-range chickens and that a low stocking density of 6 m²/hen was optimal to Beijing-you chickens grazing mixed-grass pastures.

Molecular Mechanisms of Microbiota-Mediated Pathology in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is one of the most prevalent functional gastrointestinal disorders, and accumulating evidence gained in both preclinical and clinical studies indicate the involvement of enteric microbiota in its pathogenesis. Gut resident microbiota appear to influence brain activity through the enteric nervous system, while their composition and function are affected by the central nervous system. Based on these results, the term “brain–gut–microbiome axis” has been proposed and enteric microbiota have become a potential therapeutic target in IBS cases. However, details regarding the microbe-related pathophysiology of IBS remain elusive. This review summarizes the existing knowledge of molecular mechanisms in the pathogenesis of IBS as well as recent progress related to microbiome-derived neurotransmitters, compounds, metabolites, neuroendocrine factors, and enzymes.

Metabolic Responses to Butyrate Supplementation in LF- and HF-Fed Mice Are Cohort-Dependent and Associated with Changes in Composition and Function of the Gut Microbiota

The gut microbiota and associated metabolites have emerged as potential modulators of pathophysiological changes in obesity and related metabolic disorders. Butyrate, a product of bacterial fermentation, has been shown to have beneficial effects in obesity and rodent models of diet-induced obesity. Here, we aimed to determine the beneficial effects of butyrate (as glycerol ester of butyrate monobutyrin, MB) supplementation on metabolic phenotype, intestinal permeability and inflammation, feeding behavior, and the gut microbiota in low-fat (LF)- and high-fat (HF)-fed mice. Two cohorts (separated by 2 weeks) of male C57BL/6J mice (n = 24 in each cohort, 6/group/cohort; 6 weeks old) were separated into four weight-matched groups and fed either a LF (10 % fat/kcal) or HF (45% fat/kcal) with or without supplementation of MB (LF/MB or HF/MB) at 0.25% (w/v) in drinking water for 6 weeks. Metabolic phenotypes (body weight and adiposity), intestinal inflammation, feeding behavior, and fecal microbiome and metabolites were measured. Despite identical genetic and experimental conditions, we found marked differences between cohorts in the response (body weight gain, adiposity, and intestinal permeability) to HF-diet and MB. Notably, the composition of the gut microbiota was significantly different between cohorts, characterized by lower species richness and differential abundance of a large number of taxa, including subtaxa from five phyla, including increased abundance of the genera Bacteroides, Proteobacteria, and Parasutterella in cohort 2 compared to cohort 1. These differences may have contributed to the differential response in intestinal permeability to the HF diet in cohort 2. MB supplementation had no significant effect on metabolic phenotype, but there was a trend to protect from HF-induced impairments in intestinal barrier function in cohort 1 and in sensitivity to cholecystokinin (CCK) in both cohorts. These data support the concept that microbiota composition may have a crucial effect on metabolic responses of a host to dietary interventions and highlight the importance of taking steps to ensure reproducibility in rodent studies.

Flammulina velutipes polysaccharide improves C57BL/6 mice gut health through regulation of intestine microbial metabolic activity

Flammulina velutipes polysaccharides (FVP) can improve gut health through gut microbiota and metabolism regulation. In this study, the 28-days fed experiment was used to investigate gut microbime and metabolic profiling induced by FVP. After treatment, intestinal tissue section showed the higher villus height and villus height/crypt depth (V/C) value in FVP-treated group. The 16 s rRNA gene sequencing revealed microbiota composition alteration caused by FVP, as the Firmicutes phylum increased while Bacteroidetes phylum slightly decreased. The metabolic profiling was detected by LC/MS and results showed 56 and 99 compounds were dramatically changed after FVP treatment in positive and negative ion mode, respectively. Annotation in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways displayed the adjustment of energy metabolism, amino acid metabolism, nucleotide metabolism and other related basic pathways after FVP treatment. Our study suggested that FVP can be developed as a dietary supplement for intestine health promotion.

Green tea leaf powder prevents dyslipidemia in high-fat diet-fed mice by modulating gut microbiota

Background

In the past, most researchers paid more attention to the biological activity of tea infusion and tea polyphenols; however, the prebiotic role of tea leaf powder is still unknown. Green tea leaf powder is rich in dietary fiber and is suggested to be beneficial for human health. Only limited studies have looked at the effects of tea leaf powder (which mainly contains tea dietary fiber) on gut microbiota and health.

Objective

The purpose of our study was to determine the effects of green tea leaf powder in preventing hyperlipidemia and to understand its potential lipid-lowering mechanism.

Design

Mice in three treatment groups were fed high-fat diets (HFDs) by administering either 0.5, 1.0, or 2.0 g/kg•d dietary fiber-enriched green tea leaf powder of low, medium, or high, respectively, for 12 weeks. Serum biochemical analyses and mRNA gene expression levels of related energy and lipid metabolism biomarkers from the liver were investigated. In addition, 16S rRNA cecal microbiota and fecal short chain fatty acids (SCFAs) were tested.

Results

Green tea leaf powder reduced body weight and total cholesterol of HFD-fed mice in a dose-dependent manner. Green tea leaf powder also increased satiety hormone secretion and reduced systemic inflammation of HFD-fed mice. Real-time polymerase chain reaction (PCR) analyses reconfirmed that green tea leaf powder prevented dyslipidemia by enhancing hepatic mRNA expression levels of peroxisome proliferator-activated receptor alpha, cholesterol 7α-hydroxylase, and Adenosine triphosphate (ATP)-binding cassette transporter A1 and decreasing the expression of fatty acid synthase, sterol regulatory element-binding protein 1c, and liver X receptor. Green tea leaf powder promoted the growth of Blautia, Oscillibacter, Ruminiclostridium, Alloprevotella, and Butyrivibrio and inhibited the growth of Erysipelatoclostridium, Desulfovibrio, and Candidatus_Saccharimonas in the cecum of HFD-fed mice.

Conclusion

In summary, our results indicate that green tea leaf powder improves lipid metabolism of HFD-fed mice in a dose-dependent manner. The potential mechanism involves a synergistic role in reprogramming gut microbiota, increasing satiety hormone secretion, and reducing systemic inflammation.

Can Gut Microbiota Affect Dry Eye Syndrome?

Using metagenomics, continuing evidence has elicited how intestinal microbiota trigger distant autoimmunity. Sjögren's syndrome (SS) is an autoimmune disease that affects the ocular surface, with frequently unmet therapeutic needs requiring new interventions for dry eye management. Current studies also suggest the possible relation of autoimmune dry eye with gut microbiota. Herein, we review the current knowledge of how the gut microbiota interact with the immune system in homeostasis as well as its influence on rheumatic and ocular autoimmune diseases, and compare their characteristics with SS. Both rodent and human studies regarding gut microbiota in SS and environmental dry eye are explored, and the effects of prebiotics and probiotics on dry eye are discussed. Recent clinical studies have commonly observed a correlation between gut dysbiosis and clinical manifestations of SS, while environmental dry eye portrays characteristics in between normal and autoimmune. Moreover, a decrease in both the Firmicutes/Bacteroidetes ratio and genus Faecalibacterium have most commonly been observed in SS subjects. The presumable pathways forming the "gut dysbiosis-ocular surface-lacrimal gland axis" are introduced. This review may provide perspectives into the link between the gut microbiome and dry eye, enhance our understanding of the pathogenesis in autoimmune dry eye, and be useful in the development of future interventions.

Chitosan Oligosaccharides Suppress Nuclear Factor-Kappa B Activation and Ameliorate Experimental Autoimmune Uveoretinitis in Mice

We investigated the therapeutic potential and mechanism of chitosan oligosaccharides (COS) for experimental autoimmune uveoretinitis (EAU) in mice. EAU was induced in C57/BL6 mice by injection of human interphotoreceptor retinoid-binding protein (IRBP) peptides. At the same time, a high or low dose (20 or 10 mg/kg) of COS or phosphate-buffered saline (PBS) was given to mice daily after EAU induction. We found that mouse EAU is ameliorated by the high-dose COS treatment when compared with PBS treatment. In the retinas of high-dose COS-treated mice, the nuclear translocation of NF-κB subunit (p65) was suppressed, and the expression of several key EAU inflammatory mediators, IFN-γ, TNF-α, IL-1α, IL-4, IL-5, IL-6, IL-10, IL-17 and MCP-1 was lowered. These results suggest that COS may be a potential treatment for posterior uveitis.

Conserved Calcium-Binding Residues at the Ca-I Site Involved in Fructooligosaccharide Synthesis by Lactobacillus reuteri 121 Inulosucrase

Inulosucrase is an enzyme that synthesizes inulin-type β-2,1-linked fructooligosaccharides (IFOS) from sucrose. Previous studies have shown that calcium is important for the activity and stability of Lactobacillus reuteri 121 inulosucrase (LrInu). Here, mutational analyses of four conserved calcium-binding site I (Ca-I) residues of LrInu, Asp418, Gln449, Asn488, and Asp520 were performed. Alanine substitution for these residues not only reduced the stability and activity of LrInu, but also modulated the pattern of the IFOS produced. Circular dichroism spectroscopy and molecular dynamics simulation indicated that these mutations had limited impact on the overall conformation of the enzyme. One of Ca-I residues most critical for controlling LrInu-mediated polymerization of IFOS, Asp418, was also subjected to mutagenesis, generating D418E, D418H, D418L, D418N, D418S, and D418W. The activity of these mutants demonstrated that the IFOS chain length could be controlled by a single mutation at the Ca-I site.

Maturation of the gut microbiome during the first year of life contributes to the protective farm effect on childhood asthma

Growing up on a farm is associated with an asthma-protective effect, but the mechanisms underlying this effect are largely unknown. In the Protection against Allergy: Study in Rural Environments (PASTURE) birth cohort, we modeled maturation using 16S rRNA sequence data of the human gut microbiome in infants from 2 to 12 months of age. The estimated microbiome age (EMA) in 12-month-old infants was associated with previous farm exposure (β = 0.27 (0.12-0.43), P = 0.001, n = 618) and reduced risk of asthma at school age (odds ratio (OR) = 0.72 (0.56-0.93), P = 0.011). EMA mediated the protective farm effect by 19%. In a nested case-control sample (n = 138), we found inverse associations of asthma with the measured level of fecal butyrate (OR = 0.28 (0.09-0.91), P = 0.034), bacterial taxa that predict butyrate production (OR = 0.38 (0.17-0.84), P = 0.017) and the relative abundance of the gene encoding butyryl-coenzyme A (CoA):acetate-CoA-transferase, a major enzyme in butyrate metabolism (OR = 0.43 (0.19-0.97), P = 0.042). The gut microbiome may contribute to asthma protection through metabolites, supporting the concept of a gut-lung axis in humans.

Vitamin D and Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD): An Update

Non-alcoholic fatty liver disease (NAFLD) is the first cause of chronic liver disease worldwide; it ranges from simple steatosis to steatohepatitis (NASH) and, potentially, cirrhosis and hepatocarcinoma. NAFLD is also an independent risk factor for type 2 diabetes, cardiovascular diseases, and mortality. As it is largely associated with insulin resistance and related disorders, NAFLD has been recently re-named as Metabolic dysfunction-Associated Fatty Liver Disease (MAFLD). At present, there are no approved pharmacological treatments for this condition. Vitamin D is a molecule with extensive anti-fibrotic, anti-inflammatory, and insulin-sensitizing properties, which have been proven also in hepatic cells and is involved in immune-metabolic pathways within the gut–adipose tissue–liver axis. Epidemiological data support a relationship hypovitaminosis D and the presence of NAFLD and steatohepatitis (NASH); however, results from vitamin D supplementation trials on liver outcomes are controversial. This narrative review provides an overview of the latest evidence on pathophysiological pathways connecting vitamin D to NAFLD, with emphasis on the effects of vitamin D treatment in MAFLD by a nonsystematic literature review of PubMed published clinical trials. This article conforms to the Scale for Assessment of Narrative Review Articles (SANRA) guidelines. Evidence so far available supports the hypothesis of potential benefits of vitamin D supplementation in selected populations of NAFLD patients, as those with shorter disease duration and mild to moderate liver damage.

Mucosal IgA Prevents Commensal Candida albicans Dysbiosis in the Oral Cavity

The fungus Candida albicans colonizes the oral mucosal surface of 30–70% of healthy individuals. Due to local or systemic immunosuppression, this commensal fungus is able to proliferate resulting in oral disease, called oropharyngeal candidiasis (OPC). However, in healthy individuals C. albicans causes no harm. Unlike humans mice do not host C. albicans in their mycobiome. Thus, oral fungal challenge generates an acute immune response in a naive host. Therefore, we utilized C. albicans clinical isolates which are able to persist in the oral cavity without causing disease to analyze adaptive responses to oral fungal commensalism. We performed RNA sequencing to determine the transcriptional host response landscape during C. albicans colonization. Pathway analysis revealed an upregulation of adaptive host responses due to C. albicans oral persistence, including the upregulation of the immune network for IgA production. Fungal colonization increased cross-specific IgA levels in the saliva and the tongue, and IgA⁺ cells migrated to foci of fungal colonization. Binding of IgA prevented fungal epithelial adhesion and invasion resulting in a dampened proinflammatory epithelial response. Besides CD19⁺ CD138⁻ B cells, plasmablasts, and plasma cells were enriched in the tongue of mice colonized with C. albicans suggesting a potential role of B lymphocytes during oral fungal colonization. B cell deficiency increased the oral fungal load without causing severe OPC. Thus, in the oral cavity B lymphocytes contribute to control commensal C. albicans carriage by secreting IgA at foci of colonization thereby preventing fungal dysbiosis.

The physiological functions and pharmaceutical applications of inulin: A review

Inulin (IN), a fructan-type plant polysaccharide, is widely found in nature. The major plant sources of IN include chicory, Jerusalem artichoke, dahlia etc. Studies have found that IN possessed a wide array of biological activities, e.g. as a prebiotic to improve the intestinal microbe environment, regulating blood sugar, regulating blood lipids, antioxidant, anticancer, immune regulation and so on. Currently, IN is widely used in the food and pharmaceutical industries. IN can be used as thickener, fat replacer, sweetener and water retaining agent in the food industry. IN also can be applied in the pharmaceutics as stabilizer, drug carrier, and auxiliary therapeutic agent for certain diseases such as constipation and diabetes. This paper reviews the physiological functions of IN and its applications in the field of pharmaceutics, analyzes its present research status and future research direction. This review will serve as a one-in-all resource for the researchers who are interested to work on IN.

Effects of phycocyanin on pulmonary and gut microbiota in a radiation-induced pulmonary fibrosis model

Objective

Radiation pneumonia and fibrosis are major clinical complications of radiotherapy for thoracic tumor patients, and may significantly reduce survival and quality of life. At present, no safe and effective radiation protection measures have been approved for clinical use. Phycocyanin, a protein responsible for photosynthesis from Spirulina, has been shown to have a variety of biological activities and to be beneficial for a variety of diseases, including pulmonary fibrosis. However, the preventive and protective effects of phycocyanin on radiation-induced pulmonary fibrosis have not been studied.

Design

X-ray single dose irradiation was used on the chest of mice to prepare a mouse model of pulmonary fibrosis, from which the effect of phycocyanin on pulmonary histopathologic change, pulmonary fibrosis, the microbiota in lung and gut, LPS, TNF-α, and IL-6 at different time after irradiation were evaluated.

Results

Phycocyanin alleviated the radiation-induced lung injury and reduced the level of inflammatory factors. Thorax irradiation led to the disorder in microbiota of the lung and gut. The variation trend of the diversity of the two tissues was opposite, but that of the microbiota composition was similar. The phycocyanin intervention regulated the composition of the lung and gut microbiota, transformed them into normal state, and reduced the level of LPS, which significantly reduced the abundance of inflammation-related bacteria, and increased the abundance of probiotics that produce short-chain fatty acids.

Conclusion

Phycocyanin could regulate the radiation-induced disorder in lung and gut microbiota of mice, and reduce the radiation-induced lung inflammation and fibrosis.

Mast cells crosstalk with B cells in the gut and sustain IgA response in the inflamed intestine

B lymphocytes are among the cell types whose effector functions are modulated by mast cells (MCs). The B/MC crosstalk emerged in several pathological settings, notably the colon of inflammatory bowel disease (IBD) patients is a privileged site in which MCs and IgA⁺ cells physically interact. Herein, by inducing conditional depletion of MCs in red MC and basophil (RMB) mice, we show that MCs control B cell distribution in the gut and IgA serum levels. Moreover, in dextran sulfate sodium (DSS)-treated RMB mice, the presence of MCs is fundamental for the enlargement of the IgA⁺ population in the bowel and the increase of systemic IgA production. Since both conventional B-2 and peritoneal-derived B cells populate the intestine and communicate with MCs in physiological conditions and during inflammation, we further explored this interplay through the use of co-cultures. We show that MCs finely regulate different aspects of splenic B cell biology while peritoneal B cells are unresponsive to the supporting effects provided by MCs. Interestingly, peritoneal B cells induce a pro-inflammatory skewing in MCs, characterized by increased ST2 and TNF-α expression. Altogether, this study uncovers the versatility of the B/MC liaison and highlights key aspects for the resolution of intestinal inflammation.

Beneficial Effects of Newly Isolated Akkermansia muciniphila Strains from the Human Gut on Obesity and Metabolic Dysregulation

The identification of new probiotics with anti-obesity properties has attracted considerable interest. In the present study, the anti-obesity activities of Akkermansia muciniphila (A. muciniphila) strains isolated from human stool samples and their relationship with the gut microbiota were evaluated using a high fat-diet (HFD)-fed mice model. Three strains of A. muciniphila were chosen from 27 isolates selected based on their anti-lipogenic activity in 3T3-L1 cells. The anti-lipogenic, anti-adipogenic and anti-obesity properties of these three strains were evaluated further in HFD-induced obese mice. The animals were administered these strains six times per week for 12 weeks. The treatment improved the HFD-induced metabolic disorders in mice in terms of the prevention of body weight gain, caloric intake and reduction in the weights of the major adipose tissues and total fat. In addition, it improved glucose homeostasis and insulin sensitivity. These effects were also associated with the inhibition of low-grade intestinal inflammation and restoration of damaged gut integrity, prevention of liver steatosis and improvement of hepatic function. These results revealed a difference in the distribution pattern of the gut microbial communities between groups. Therefore, the gut microbial population modulation, at least in part, might contribute to the beneficial impact of the selected A. muciniphila strains against metabolic disorders.

Evaluation of the Prebiotic Potential of a Commercial Synbiotic Food Ingredient on Gut Microbiota in an Ex Vivo Model of the Human Colon

Behavior and mood disorders have been linked to gut microbiota dysbiosis through the “microbiota-gut-brain axis”. Microbiota-targeting interventions are promising therapeutic modalities to restore or even maintain normal microbiome composition and activity in these disorders. Here, we test the impact of a commercial synbiotic formulation on gut microbiota composition and metabolic activity. We employed an ex-vivo continuous fermentation model that simulates the proximal colon to assess the effect of this formulation on microbiota structure and functionality as compared to no treatment control and microcrystalline cellulose as a dietary fiber control. The test formulation did not alter the diversity of gut microbiota over 48 h of treatment. However, it induced the enrichment of Lactobacillus, Collinsella and Erysipelotrichaceae. The test formulation significantly increased the level of microbiota-generated butyrate within 12 h of treatment as compared to 24 h required by microcrystalline cellulose to boost its production. The test formulation did not lead to a significant change in amino acid profiles. These results provide evidence of potential benefits related to synbiotic effects and general gut health and support the potential of this food formulation as a therapeutic dietary intervention in mood and behavior disorders.

The adaptive immune response to Clostridioides difficile: A tricky balance between immunoprotection and immunopathogenesis

Clostridioides difficile (C. difficile) is the major cause of hospital-acquired gastrointestinal infections in individuals following antibiotics treatment. The pathogenesis of C. difficile infection (CDI) is mediated mainly by the production of toxins that induce tissue damage and host inflammatory responses. While innate immunity is well characterized in human and animal models of CDI, adaptive immune responses remain poorly understood. In this review, the current understanding of adaptive immunity is summarized and its influence on pathogenesis and disease outcome is discussed. The perspectives on what we believe to be the main pending questions and the focus of future research are also provided. There is no doubt that the innate immune response provides a first line of defense to CDI. But, is the adaptive immune response a friend or a foe? Probably it depends on the course of the disease. Adaptive immunity is essential for pathogen eradication, but may also trigger uncontrolled or pathological inflammation. Most of the understanding of the role of T cells is based on findings from experimental models. While they are a very valuable tool for research studies, more studies in human are needed to translate these findings into human disease. Another main challenge is to unravel the role of the different T cell populations on protection or induction of immunopathogenesis.

Cross-talk between airway and gut microbiome links to IgE responses to house dust mites in childhood airway allergies

A connection between airway and gut microbiota related to allergen exposure in childhood allergies was not well addressed. We aimed to identify the microbiota alterations in the airway and gut related to mite-specific IgE responses in young children with airway allergies. This study enrolled 60 children, including 38 mite-sensitized children (20 rhinitis and 18 asthma), and 22 non-mite-sensitized healthy controls. Microbiome composition analysis of the throat swab and stool samples was performed using bacterial 16S rRNA sequencing. An integrative analysis of the airway and stool microbial profiling associated with IgE reactions in childhood allergic rhinitis and asthma was examined. The Chao1 and Shannon indices in the airway were significantly lower than those in the stool. Additionally, an inverse association of the airway microbial diversity with house dust mite (HDM) sensitization and allergic airway diseases was noted. Fecal IgE levels were positively correlated with the serum Dermatophagoides pteronyssinus- and Dermatophagoides farinae-specific IgE levels. Airway Leptotrichia spp. related to asthma were strongly correlated with fecal Dorea and Ruminococcus spp., which were inversely associated with fecal IgE levels and risk of allergic rhinitis. Moreover, four airway genera, Campylobacter, Selenomonas, Tannerella, and Atopobium, were negatively correlated with both serum mite-specific and fecal IgE levels. Among them, the airway Selenomonas and Atopobium spp. were positively correlated with stool Blautia and Dorea spp. related to asthma and allergic rhinitis, respectively. In conclusion, airway microbial dysbiosis in response to HDM and its cross-talk with the gut microbial community is related to allergic airway diseases in early childhood.

Primary human colonic mucosal barrier crosstalk with super oxygen-sensitive Faecalibacterium prausnitzii in continuous culture

Background

The gut microbiome plays an important role in human health and disease. Gnotobiotic animal and in vitro cell-based models provide some informative insights into mechanistic crosstalk. However, there is no existing system for a long-term co-culture of a human colonic mucosal barrier with super oxygen-sensitive commensal microbes, hindering the study of human-microbe interactions in a controlled manner.

Methods

Here, we investigated the effects of an abundant super oxygen-sensitive commensal anaerobe, Faecalibacterium prausnitzii, on a primary human mucosal barrier using a Gut-MIcrobiome (GuMI) physiome platform that we designed and fabricated.

Findings

Long-term continuous co-culture of F. prausnitzii for two days with colon epithelia, enabled by continuous flow of completely anoxic apical media and aerobic basal media, resulted in a strictly anaerobic apical environment fostering growth of and butyrate production by F. prausnitzii, while maintaining a stable colon epithelial barrier. We identified elevated differentiation and hypoxia-responsive genes and pathways in the platform compared with conventional aerobic static culture of the colon epithelia, attributable to a combination of anaerobic environment and continuous medium replenishment. Furthermore, we demonstrated anti-inflammatory effects of F. prausnitzii through HDAC and the TLR-NFKB axis. Finally, we identified that butyrate largely contributes to the anti-inflammatory effects by downregulating TLR3 and TLR4.

Conclusions

Our results are consistent with some clinical observations regarding F. prausnitzii, thus motivating further studies employing this platform with more complex engineered colon tissues for understanding the interaction between the human colonic mucosal barrier and microbiota, pathogens, or engineered bacteria.

Effects of choline supplementation on liver biology, gut microbiota, and inflammation in Helicobacter pylori-infected mice

AIMS

Diet is one of the factors affecting the pathogenicity of Helicobacter pylori (H. pylori) infection. Choline is a dietary component that is crucial for normal cellular function. However, choline intake imbalance can lead to liver injury, inflammation, and changes of the gut microbiota composition. The study aimed to explore the effects of choline supplementation on liver biology, gut microbiota, and inflammation in H. pylori-infected mice.

MAIN METHODS

Liver function was detected by biochemical and histopathological analysis. Serum inflammatory markers were measured using ELISA. Fecal microbial profiles were determined via 16S rRNA sequencing.

KEY FINDINGS

The results showed that choline supplementation decreased serum LDL level, while increased the activities of serum AST and ALT in normal BALB/c mice. Besides, choline also reduced hepatic SOD and GSH-Px activities, and elevated hepatic MDA level of H. pylori-infected mice. Moreover, choline markedly enhanced the concentrations of inflammatory factors including LPS, CRP, IL-6, TNF-α, and CXCL1 in H. pylori-infected mice. Meanwhile, choline and H. pylori cotreatment altered the richness and diversity of the mice gut microbiota, and increased the relative abundance of Escherichia_Shigella, which had a significant positive correlation with the levels of LPS, CRP, IL-6, TNF-α and CXCL1.

SIGNIFICANCE

Our data suggest, for the first time, that choline can aggravate H. pylori-induced inflammation, which may be associated with the alterations of gut microbiota. This study may provide novel insights into the possible effects of food-derived choline on H. pylori infection-related diseases.

Lactose-Induced Chronic Diarrhea Results From Abnormal Luminal Microbial Fermentation and Disorder of Ion Transport in the Colon

Diarrhea is one of the major abdominal symptoms in lactose-intolerant subjects. The changes in the large intestinal luminal environment and disorder of the epithelial ion transport in lactose-induced diarrhea remain unclear. The present study aimed to investigate the effect of an incremental high-lactose diet (IHLD, 30%/40%/50%) on luminal microbiota, microbiota-derived metabolite concentrations and colonic ion transport. Gut microbiota were analyzed by 16S rRNA amplicon sequencing and the concentration of SCFAs by gas chromatography, galactose, lactose and lactic acid through assay kit; Ussing chamber was performed to detect basal and stimulated ion transport; The expression and location of SCFA transporters, the Na-H exchanger 3(NHE3), cystic fibrosis transporter regulater (CFTR) and NKCC1 in the colon mucosa were analyzed by western and immunostaining. The concentrations of lactose, galactose and lactic acid of the cecal content were markedly increased (P < 0.01) and SCFA concentration was significantly decreased (P < 0.01). This was associated with depletion of the Lachnospiraceae NK4A136 group and Ruminococcaceae UCG-005 and increased relative abundance of Lactobacillus, escherichia-shigella and megamonas in the cecal microbiota. The expression of monocarboxylate transporter 1 was decreased in the colonic mucosa of the IHLD group. Low NHE3 expression and phosphorylation levels, and decreases in delta basal short circuit current after apical Na⁺ removal in the colonic mucosa of the IHLD group contributed to Na⁺ accumulation in the lumen and decrease stimulated Cl^– secretion with low CFTR and NKCC1 expression would compensate for water and electrolyte loss during the diarrhea process. These results indicated that the persistence of the diarrhea state was maintained by abnormal colonic microbiota fermentation leading to high concentrations of lactose, galactose and lactic acid and low SCFAs in the lumen, and decreased Na⁺ absorption with the low NHE3 expression and phosphorylation levels.

Influence of the Fermented Feed and Vaccination and Their Interaction on Parameters of Large White/Norwegian Landrace Piglets

The aim of this study was to evaluate the influence of fermented with a newly isolated lactic acid bacteria (LAB) strains combination (Lactobacillus plantarum LUHS122, Lactobacillus casei LUHS210, Lactobacillus farraginis LUHS206, Pediococcus acidilactici LUHS29, Lactobacillus plantarum LUHS135 and Lactobacillus uvarum LUHS245) feed on non-vaccinated (NV) and vaccinated with Circovac porcine circovirus type 2 vaccine (QI09AA07, CEVA-PHYLAXIA Co. Ltd. Szállás u. 5. 1107 Budapest, Hungary) piglets' blood parameters, gut microbial composition, growth performance and ammonia emission. The 36-day experiment was conducted using 25-day-old Large White/Norwegian Landrace (LW/NL) piglets, which were randomly divided into four groups with 100 piglets each: S_nonV-non-vaccinated piglets fed with control group compound feed; S_V-vaccinated piglets fed with control group compound feed; RF_nonV-non-vaccinated piglets fed with fermented compound feed; RF_V-vaccinated piglets fed with fermented compound feed. Samples from 10 animals per group were collected at the beginning and end of the experiment. Metagenomic analysis showed that fermentation had a positive impact on the Lactobacillus prevalence during the post-weaning period of pigs, and vaccination had no negative impact on microbial communities. Although a higher amount of Lactobacillus was detected in vaccinated, compared with non-vaccinated groups. At the end of experiment, there was a significantly higher LAB count in the faeces of both vaccinated compared to non-vaccinated groups (26.6% for S_V and 17.2% for RF_V), with the highest LAB count in the S_V group. At the end of experiment, the S_V faeces also had the highest total bacteria count (TBC). The RF_V group had a 13.2% increase in total enterobacteria count (TEC) at the end of experiment, and the S_V group showed a 31.2% higher yeast/mould (Y/M) count. There were no significant differences in the average daily gain (ADG) among the groups; however, there were significant differences in the feed conversion ratios (FCR) between several groups: S_V vs. S_nonV (11.5% lower in the S_V group), RF_V vs. RF_nonV (10.2% lower in the RFnonV group) and S_V vs. RF_V (21.6% lower in the S_V group). Furthermore, there was a significant, very strong positive correlation between FCR and TEC in piglets' faeces (R = 0.919, p = 0.041). The lowest ammonia emission was in RF_V group section (58.2, 23.8, and 47.33% lower compared with the S_nonV, S_V and RF_nonV groups, respectively). Notably, there was lower ammonia emission in vaccinated groups (45.2% lower in S_V vs. S_nonV and 47.33% lower in RF_V vs. RF_nonV). There was also a significant, very strong positive correlation between ammonia emission and Y/M count in piglets' faeces at the end of the experiment (R = 0.974; p = 0.013). Vaccination as a separate factor did not significantly influence piglets' blood parameters. Overall, by changing from an extruded soya to cheaper rapeseed meal and applying the fermentation model with the selected LAB combination, it is possible to feed piglets without any undesirable changes in health and growth performance in a more sustainable manner. However, to evaluate the influence of vaccination and its interaction with other parameters (feed, piglets' age, breed, etc.) on piglets' parameters, additional studies should be performed and methods should be standardised to ensure the results may be compared.

Spirulina platensis alleviates chronic inflammation with modulation of gut microbiota and intestinal permeability in rats fed a high-fat diet

Recent research suggested that taking a high-fat diet (HFD) may lead to a gut microbiota imbalance and colon tissue damage. This would lead to increased intestinal permeability and consequent constant circulation of low-grade inflammatory cytokines. Spirulina platensis can protect against HFD-induced metabolic inflammation and can stimulate the growth of beneficial bacteria in in vitro stool cultures. However, it is unknown whether this beneficial effect acts on intestinal tissues. In this study, rats were fed a high-fat diet fed with 3% S platensis for 14 weeks. We analysed endotoxin, the composition of the microbiota, inflammation and gut permeability. We found that S platensis decreased the bodyweight and visceral fat pads weight of the HFD-fed rats. In addition, it lowered the levels of lipopolysaccharide and pro-inflammatory cytokines in serum. Our results showed that S platensis could largely reduce the relative amount of Proteobacteria and the Firmicutes/Bacteroidetes ratio in faecal samples from HFD-fed rats. S platensis significantly reduced intestinal inflammation, as shown by decreased expression of myeloid differentiation factor 88 (MyD88), toll-like receptor 4 (TLR4), NF-κB (p65) and inflammatory cytokines. S platensis also ameliorated the increased permeability and decreased expression of tight junction proteins in the intestinal mucosa, such as ZO-1, Occludin and Claudin-1. Therefore, in HFD-induced gut dysbiosis rats, S platensis benefits health by inhibiting chronic inflammation and gut dysbiosis, and modulating gut permeability.

Combinatorial Effects of Soluble, Insoluble, and Organic Extracts from Jerusalem Artichokes on Gut Microbiota in Mice

Jerusalem artichokes contain high amounts of inulin, which is a prebiotic that supports digestive health, as well as a variety of insoluble fibers and caffeoylquinic acid. The individual impact of these components on gut microbiota is well known; however, the combinatorial effects are less clear. In this investigation, we fractionated Jerusalem artichokes into three parts (water-soluble extract, insoluble extract, and organic extract) and powdered them. Mice were fed a high-fat diet that included one or more of these extracts for 10 days, and then their cecal pH, cecal short-chain fatty acids (SCFAs), and fecal microbiota were evaluated. The combination of the water-soluble and organic extract decreased cecal pH and increased the concentration of SCFAs and led to dynamic changes in the composition of the gut microbiota. These results demonstrate that both the water-soluble and organic extracts in Jerusalem artichokes are bioactive substances that are capable of changing SCFA production and the composition of gut microbiota. Powdered Jerusalem artichokes, rather than inulin supplements, may be superior for promoting a healthy gut.

The Gut-liver Axis in Immune Remodeling: New insight into Liver Diseases

The gut microbiota consists of a dynamic multispecies community of bacteria, fungi, archaea, and protozoans, playing a fundamental role in the induction, training, and function of the host immune system. The liver is anatomically and physiologically linked to the gut microbiota via enterohepatic circulation, specifically receiving intestine-derived blood through the portal vein. The gut microbiota is crucial for maintaining immune homeostasis of the gut-liver axis. A shift in gut microbiota composition can result in activation of the mucosal immune response causing homeostasis imbalance. This imbalance results in translocation of bacteria and migration of immune cells to the liver, which is related to inflammation-mediated liver injury and tumor progression. In this review, we outline the role of the gut microbiota in modulating host immunity and summarize novel findings and recent advances in immune-based therapeutics associated with the gut-liver axis. Moving forward, a deep understanding of the microbiome-immune-liver axis will provide insight into the basic mechanisms of gut microbiota dysbiosis affecting liver diseases.

Intraepithelial T Cells Diverge by Intestinal Location as Pigs Age

T cells resident within the intestinal epithelium play a central role in barrier integrity and provide a first line of immune defense. Intraepithelial T cells (IETs) are among the earliest immune cells to populate and protect intestinal tissues, thereby giving them an important role in shaping gut health early in life. In pigs, IETs are poorly defined, and their maturation in young pigs has not been well-studied. Given the importance of IETs in contributing to early life and long-term intestinal health through interactions with epithelial cells, the microbiota, and additional environmental factors, a deeper characterization of IETs in pigs is warranted. The objective of this study was to analyze age- and intestinal location-dependent changes in IETs across multiple sites of the small and large intestine in pigs between 4- and 8-weeks of age. IETs increased in abundance over time and belonged to both γδ and αβ T cell lineages. Similar compositions of IETs were identified across intestinal sites in 4-week-old pigs, but compositions diverged between intestinal sites as pigs aged. CD2⁺CD8α⁺ γδ T cells and CD4^-CD8α⁺ αβ T cells comprised >78% of total IETs at all intestinal locations and ages examined. Greater percentages of γδ IETs were present in large intestine compared to small intestine in older pigs. Small intestinal tissues had greater percentages of CD2⁺CD8α^- γδ IETs, while CD2⁺CD8α⁺ γδ IET percentages were greater in the large intestine. Percentages of CD4^-CD8α⁺ αβ IETs increased over time across all intestinal sites. Moreover, percentages of CD27⁺ cells decreased in ileum and large intestine over time, indicating increased IET activation as pigs aged. Percentages of CD27⁺ cells were also higher in small intestine compared to large intestine at later timepoints. Results herein emphasize 4- to 8-weeks of age as a critical window of IET maturation and suggest strong associations between intestinal location and age with IET heterogeneity in pigs.

Inulin and milk mineral fortification of a pork sausage exhibits distinct effects on the microbiome and biochemical activity in the gut of healthy rats

This study investigated inulin and calcium-rich milk mineral incorporation into a pork sausage in order to examine the effects on microbiome and biochemical activity in the gastrointestinal tract upon ingestion. Rats (n = 48) were fed one of four sausages; a pork sausage enriched with 1) inulin (6.0%) and milk mineral (3%), 2) inulin (6.0%), 3) milk mineral (3%) or 4) control sausages without enrichment. NMR-based metabolomics revealed that inulin-enrichment increased the fecal concentration of short-chain fatty acids (SCFAs). Milk mineral-enrichment also increased SCFA concentrations, although less pronounced. In addition, milk mineral reduced the concentration of nitroso compounds in feces and small intestinal content. Combined enrichment with both inulin and milk mineral showed no cumulative effect on SCFA formation and seemed to oppose the milk mineral-induced reduction of nitroso compound formation. 16S rRNA gene amplicon sequencing indicated that alterations of the gut microbiome contributed to the observed effects.

Spatial Compartmentalization of the Microbiome between the Lumen and Crypts Is Lost in the Murine Cecum following the Process of Surgery, Including Overnight Fasting and Exposure to Antibiotics

The cecum is a unique region in the mammalian intestinal tract in which the microbiome is localized to two compartments, the lumen and the crypts. The microbiome within crypts is particularly important as it is in direct contact with lining epithelial cells including stem cells. Here, we analyzed the microbiome in cecum of mice using multiple techniques including metagenomics. The lumen microbiome comprised Firmicutes and Bacteroidetes whereas the crypts were dominated by Proteobacteria and Deferribacteres, and the mucus comprised a mixture of these 4 phyla. The lumen microbial functional potential comprised mainly carbon metabolism, while the crypt microbiome was enriched for genes encoding stress resistance. In order to determine how this structure, assembly, and function are altered under provocative conditions, we exposed mice to overnight starvation (S), antibiotics (A), and a major surgical injury (partial hepatectomy [H]), as occurs with major surgery in humans. We have previously demonstrated that the combined effect of this "SAH" treatment leads to a major disturbance of the cecal microbiota at the bottom of crypts in a manner that disrupts crypt cell homeostasis. Here, we applied the SAH conditions and observed a loss of compartmentalization in both composition and function of the cecal microbiome associated with major shifts in local physicochemical cues including decrease of hypoxia, increase of pH, and loss of butyrate production. Taken together, these studies demonstrated a defined order, structure, and function of the cecal microbiome that can be disrupted under provocative conditions such as major surgery and its attendant exposures.IMPORTANCE The proximal colon and cecum are two intestinal regions in which the microbiome localizes to two spatially distinct compartments, the lumen and crypts. The differences in composition and function of luminal and crypt microbiome in the cecum and the effect of physiological stress on their compartmentalization remain poorly characterized. Here, we characterized the composition and function of the lumen-, mucus-, and crypt-associated microbiome in the cecum of mice. We observed a highly ordered microbial architecture within the cecum whose assembly and function become markedly disrupted when provoked by physiological stress such as surgery and its attendant preoperative treatments (i.e., overnight fasting and antibiotics). Major shifts in local physicochemical cues including a decrease in hypoxia levels, an increase in pH, and a loss of butyrate production were associated with the loss of compositional and functional compartmentalization of the cecal microbiome.

Altered nutrient status reprograms host inflammation and metabolic health via gut microbiota

The metabolism of macro- and micronutrients is a complex and highly regulated biological process. An imbalance in the metabolites and their signaling networks can lead to nonresolving inflammation and consequently to the development of chronic inflammatory-associated diseases. Therefore, identifying the accumulated metabolites and altered pathways during inflammatory disorders would not only serve as "real-time" markers but also help in the development of nutritional therapeutics. In this review, we explore recent research that has delved into elucidating the effects of carbohydrate/calorie restriction, protein malnutrition, lipid emulsions and micronutrient deficiencies on metabolic health and inflammation. Moreover, we describe the integrated stress response in terms of amino acid starvation and lipemia and how this modulates new age diseases such as inflammatory bowel disease and atherosclerosis. Lastly, we explain the latest research on metaflammation and inflammaging. This review focuses on multiple signaling pathways, including, but not limited to, the FGF21-β-hydroxybutryate-NLRP3 axis, the GCN2-eIF2α-ATF4 pathway, the von Hippel-Lindau/hypoxia-inducible transcription factor pathway and the TMAO-PERK-FoxO1 axis. Additionally, throughout the review, we explain how the gut microbiota responds to altered nutrient status and also how antimicrobial peptides generated from nutrient-based signaling pathways can modulate the gut microbiota. Collectively, it must be emphasized that metabolic starvation and inflammation are strongly regulated by both environmental (i.e., nutrition, gut microbiome) and nonenvironmental (i.e., genetics) factors, which can influence the susceptibility to inflammatory disorders.

Interaction of dietary polyphenols and gut microbiota: Microbial metabolism of polyphenols, influence on the gut microbiota, and implications on host health

The human gastrointestinal tract is inhabited by a vast number of microorganisms that are called as the microbiota. Each individual harbors a unique gut microbial composition, this composition evolves throughout the host's lifetime and it is easily affected by internal or external changes. It has been shown that gut microbiota plays a crucial role in host's health and as this complex community has the ability to interact with each other and with the host's immune system, the presence or absence of some major species can affect the homeostasis. Diet can be considered as one of the pivotal factors in modulating the functionality, integrity, and composition of the gut microbiota as the gastrointestinal tract is the first organ exposed to components of the diet. In this review, we have focused on the effects of polyphenols, key compounds of a healthy diet with several biological activities, on the gut microbial composition, their biotransformation by the gut microbiota, and the effect of their reciprocal interactions in human health and disease.

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

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

Prevention of anastomotic leak in rectal cancer surgery with local antibiotic decontamination: a prospective, randomized, double-blind, placebo-controlled single center trial

PURPOSE

Anastomotic leak and other infectious complications are septic complications of rectal cancer surgery caused by bacteria. Data from registry analysis show a beneficial effect of local antimicrobial administration on anastomotic leaks, but data are inconsistent in recent clinical trials. Therefore, our aim was to study the efficacy of topical antibiotic treatment on the incidence of anastomotic leaks in rectal cancer surgery.

METHODS

A prospective, randomized, double-blind and placebo-controlled, single center trial was conducted. Patients received either placebo and amphotericin B or decontamination with polymyxin B, tobramycin, vancomycin, and amphotericin B four times per day starting the day before surgery until postoperative day 7. If a protective ileostomy was created, a catheter was placed transanally and the medication was administered locally to the anastomotic site. All patients received an intravenous perioperative antibiotic prophylaxis.

RESULTS

The trial had to be stopped for ethical reasons after first interim analysis with 80 patients instead of the initially planned 280 patients. Of the 40 patients randomized to receive placebo, eight (20%) developed anastomotic leak compared to only 2 (5%) in the treatment group of 40 patients (decontamination) with significant difference in the χ² test (p = 0.0425). Twenty percent of the placebo group and 12.5% in the treatment group developed infectious complications not associated with anastomotic leak (p = 0.5312). One patient (2.5%) in the placebo group died (p = 0.3141).

CONCLUSION

Local decontamination with polymyxin, tobramycin, vancomycin, and amphotericin B is safe and effective in the prevention of anastomotic leak in rectal cancer surgery.

A story of liver and gut microbes: how does the intestinal flora affect liver disease? A review of the literature

Each individual is endowed with a unique gut microbiota (GM) footprint that mediates numerous host-related physiological functions, such as nutrient metabolism, maintenance of the structural integrity of the gut mucosal barrier, immunomodulation, and protection against microbial pathogens. Because of increased scientific interest in the GM, its central role in the pathophysiology of many intestinal and extraintestinal conditions has been recognized. Given the close relationship between the gastrointestinal tract and the liver, many pathological processes have been investigated in the light of a microbial-centered hypothesis of hepatic damage. In this review we introduce to neophytes the vast world of gut microbes, including prevalent bacterial distribution in healthy individuals, how the microbiota is commonly analyzed, and the current knowledge of the role of GM in liver disease pathophysiology. Also, we highlight the potentials and downsides of GM-based therapy.

The protective mechanisms of macroalgae Laminaria japonica consumption against lipid metabolism disorders in high-fat diet-induced hyperlipidemic rats

Macroalgae Laminaria japonica (MLJ) has been reported to exhibit various biological activities including improving immunity, anti-aging, anti-tumor, anti-atherosclerosis and anti-diabetic, but the protective mechanisms of MLJ consumption against non-alcoholic fatty liver disease (NAFLD) associated with hyperlipidemia remain poorly understood. This study demonstrated that MLJ consumption prevented high-fat diet (HFD)-induced NAFLD associated with hyperlipidemia in a rat model, and improved hyperlipidemia-related parameters, e.g. serum and hepatic lipid profiles. Moreover, histological analysis showed that MLJ reduced lipid deposition in adipocytes and hepatocytes compared with the HFD group. Such beneficial effects may be associated with the modulation of the intestinal microbiota, especially some key microbial phylotypes involved in lipid metabolism homeostasis. The underlying protective mechanisms of MLJ consumption against HFD-induced NAFLD associated with hyperlipidemia were also studied by ultra-high performance liquid chromatography with quadruple-time of flight mass spectrometry (UPLC-QTOF/MS)-based liver metabolomics coupled with pathway analysis. The metabolic pathway enrichment analysis of the differentially abundant hepatic metabolites indicated that primary bile acid biosynthesis metabolism and cysteine and methionine metabolism were the two main metabolic pathways altered by MLJ consumption when compared with the model group. The analysis of the transcription levels of liver-related genes by RT-qPCR and the expressions of liver-related proteins by immunohistochemistry (IHC) showed that MLJ consumption could regulate the levels of mRNA transcription and protein expression related to hepatic lipid metabolism. In short, this study indicates that MLJ could be developed as functional food supplement for the prevention or treatment of NAFLD associated with hyperlipidemia.

Levansucrase from Bacillus amyloliquefaciens KK9 and Its Y237S Variant Producing the High Bioactive Levan-Type Fructooligosaccharides

Levan-typed fructooligosaccharide (LFOS), a β-2,6 linked oligofructose, displays the potential application as a prebiotic and therapeutic dietary supplement. In the present study, LFOS was synthesized using levansucrase from Bacillus amyloliquefaciens KK9 (LsKK9). The wild-type LsKK9 was cloned and expressed in E. coli, and purified by cation exchanger chromatography. Additionally, Y237S variant of LsKK9 was constructed based on sequence alignment and structural analysis to enhance the LFOS production. High-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD) analysis indicated that Y237S variant efficiently produced a higher amount of short-chain LFOS than wild type. Also, the concentration of enzyme and sucrose in the reactions was optimized. Finally, prebiotic activity assay demonstrated that LFOS produced by Y237S variant had higher prebiotic activity than that of the wild-type enzyme, making the variant enzyme attractive for food biotechnology.

Fermentable Dietary Fiber Promotes Helminth Infection and Exacerbates Host Inflammatory Responses

Fermentable dietary fibers promote the growth of beneficial bacteria, can enhance mucosal barrier integrity, and reduce chronic inflammation. However, effects on intestinal type 2 immune function remain unclear. In this study, we used the murine whipworm Trichuris muris to investigate the effect of the fermentable fiber inulin on host responses to infection regimes that promote distinct Th1 and Th2 responses in C57BL/6 mice. In uninfected mice, dietary inulin stimulated the growth of beneficial bacteria, such as Bifidobacterium (Actinobacteria) and Akkermansia (Verrucomicrobia). Despite this, inulin prevented worm expulsion in normally resistant mice, instead resulting in chronic infection, whereas mice fed an equivalent amount of nonfermentable fiber (cellulose) expelled worms normally. Lack of expulsion in the mice fed inulin was accompanied by a significantly Th1-skewed immune profile characterized by increased T-bet⁺ T cells and IFN-γ production in mesenteric lymph nodes, increased expression of Ido1 in the cecum, and a complete absence of mast cell and IgE production. Furthermore, the combination of dietary inulin and high-dose T. muris infection caused marked dysbiosis, with expansion of the Firmicutes and Proteobacteria phyla, near elimination of Bacteroidetes, and marked reductions in cecal short-chain fatty acids. Neutralization of IFN-γ during infection abrogated Ido1 expression and was sufficient to restore IgE production and worm expulsion in inulin-fed mice. Our results indicate that, whereas inulin promoted gut health in otherwise healthy mice, during T. muris infection, it exacerbated inflammatory responses and dysbiosis. Thus, the positive effects of fermentable fiber on gut inflammation appear to be context dependent, revealing a novel interaction between diet and infection.

Alginate oligosaccharide improves lipid metabolism and inflammation by modulating gut microbiota in high-fat diet fed mice

Alginate oligosaccharides are associated with some beneficial health effects. Gut microbiota is one of the most recently identified factors in the development of several metabolic diseases induced by high-fat diet. Our objective was to evaluate how alginate oligosaccharides impact on high-fat diet‑induced features of metabolic disorders and whether this impact is related to modulations in the modulation of the gut microbiota. C57BL/6J mice were fed with chow diet, high-fat diet, or high-fat diet supplemented with alginate oligosaccharides for 10 weeks. Alginate oligosaccharide treatment improved lipid metabolism, such as reducing levels of TG and LDL-C and inhibiting expression of lipogenesis genes. Alginate oligosaccharide administration reduced the levels of fasting blood glucose and increased the levels of serum insulin. Alginate oligosaccharide treatment was found to lower the expression of markers of inflammation, including IL1β and CD11c. Alginate oligosaccharide treatment modulated gut microbial communities and markedly prompted the growth of Akkermansia muciniphila, Lactobacillus reuteri, and Lactobacillus gasseri. Additionally, alginate oligosaccharide intervention significantly increased concentrations of short-chain fatty acids, such as acetic acid, propionic acid, and butyric acid, as well as decreased levels of endotoxin. Alginate oligosaccharides exert beneficial effects via alleviating metabolic metrics induced by high-fat diet, which is associated with increase in A. muciniphila, L. reuteri, and L. gasseri, as well as the release of microbiota-dependent short-chain fatty acids and inhibition of endotoxin levels.

Alginate oligosaccharides improve germ cell development and testicular microenvironment to rescue busulfan disrupted spermatogenesis

Rationale: Busulfan is currently an indispensable anti-cancer drug, particularly for children, but the side effects on male reproduction are so serious that critical drug management is needed to minimize any negative impact. Meanwhile, alginate oligosaccharides (AOS) are natural products with many consequent advantages, that have attracted a great deal of pharmaceutical attention. In the current investigation, we performed single-cell RNA sequencing on murine testes treated with busulfan and/or AOS to define the mitigating effects of AOS on spermatogenesis at the single cell level.

Methods: Testicular cells (in vivo) were examined by single cell RNA sequencing analysis, histopathological analysis, immunofluorescence staining, and Western blotting. Testes samples (ex vivo) underwent RNA sequencing analysis. Blood and testicular metabolomes were determined by liquid chromatography-mass spectrometry (LC/MS).

Results: We found that AOS increased murine sperm concentration and motility, and rescued busulfan disrupted spermatogenesis through improving (i) the proportion of germ cells, (ii) gene expression important for spermatogenesis, and (iii) transcriptional factors in vivo. Furthermore, AOS promoted the ex vivo expression of genes important for spermatogenesis. Finally, our results showed that AOS improved blood and testis metabolomes as well as the gut microbiota to support the recovery of spermatogenesis.

Conclusions: AOS could be used to improve fertility in patients undergoing chemotherapy and to combat other factors that induce infertility in humans.

Time of Feeding Alters Obesity-Associated Parameters and Gut Bacterial Communities, but Not Fungal Populations, in C57BL/6 Male Mice

BACKGROUND

Fasting and timed feeding strategies normalize obesity parameters even under high-fat dietary intake. Although previous work demonstrated that these dietary strategies reduce adiposity and improve metabolic health, limited work has examined intestinal microbial communities.

OBJECTIVES

We determined whether timed feeding modifies the composition of the intestinal microbiome and mycobiome (yeast and fungi).

METHODS

Male C57BL/6 mice were fed a high-fat diet (HF) for 6 wk. Animals were then randomly assigned to the following groups (n = 8-10/group): 1) HF ad libitum; 2) purified high-fiber diet (Daniel Fast, DF); 3) HF-time-restricted feeding (TRF) (6 h); 4) HF-alternate-day fasting (ADF); or 5) HF at 80% total caloric restriction (CR). After 8 wk, obesity and gut parameters were characterized. We also examined changes to the gut microbiome and mycobiome before, during, and following dietary interventions.

RESULTS

Body mass gain was reduced with all restricted dietary groups. HF-fed microbiota displayed lower α-diversity along with reduced phylum levels of Bacteroidetes and increased Firmicutes. Animals switched from HF to DF demonstrated a rapid transition in bacterial taxonomic composition, α-, and β-diversity that initially resembled HF, but was distinct after 4 and 8 wk of DF feeding. Time-or calorie-restricted HF-fed groups did not show changes at the phylum level, but α-diversity was increased, with specific genera altered. Six weeks of HF feeding reduced various fungal populations, particularly Alternaria, Aspergillus, Cladosporium, and Talaromyces, and increased Candida, Hanseniaspora, and Kurtzmaniella. However, 8 wk of intervention did not change the fungal populations, with the most abundant genera being Candida, Penicillium, and Hanseniaspora.

CONCLUSIONS

These data suggest that timed-feeding protocols and diet composition do not significantly affect the gut fungal community, despite inducing measurable shifts in the bacterial population that coincide with improvements in metabolism.

Inulin with different degrees of polymerization protects against diet-induced endotoxemia and inflammation in association with gut microbiota regulation in mice

Societal lifestyle changes, especially increased consumption of a high-fat diet lacking dietary fibers, lead to gut microbiota dysbiosis and enhance the incidence of adiposity and chronic inflammatory disease. We aimed to investigate the metabolic effects of inulin with different degrees of polymerization on high-fat diet-fed C57BL/6 J mice and to evaluate whether different health outcomes are related to regulation of the gut microbiota. Short-chain and long-chain inulins exert beneficial effects through alleviating endotoxemia and inflammation. Antiinflammation was associated with a proportional increase in short-chain fatty acid-producing bacteria and an increase in the concentration of short-chain fatty acids. Inulin might decrease endotoxemia by increasing the proportion of Bifidobacterium and Lactobacillus, and their inhibition of endotoxin secretion may also contribute to antiinflammation. Interestingly, the beneficial health effects of long-chain inulin were more pronounced than those of short-chain inulin. Long-chain inulin was more dependent than short-chain inulin on species capable of processing complex polysaccharides, such as Bacteroides. A good understanding of inulin-gut microbiota-host interactions helps to provide a dietary strategy that could target and prevent high-fat diet-induced endotoxemia and inflammation through a prebiotic effect.

β-Sitosterol Attenuates High Grain Diet-Induced Inflammatory Stress and Modifies Rumen Fermentation and Microbiota in Sheep

β-sitosterol (BSS) is a plant-derived natural bioactive compound, its cellular mechanism of anti-inflammatory activity has been proven recently. Little information is available regarding the application of BSS on ruminants under high grain diet. The objective of this study was to evaluate the effects of dietary BSS supplementation on inflammatory response, ruminal fermentation characteristics and the composition of the ruminal bacterial community under high grain diet. Eight rumen-cannulated Hu sheep (59.7 ± 4.8 kg of initial body weight) were randomly assigned into a replicated 4 × 4 Latin square design trial. Sheep were fed a high grain diet (non-fiber carbohydrate: neutral detergent fiber = 2.03) supplemented either with 0.25 (LBS), 0.5 (MBS), 1.0 (HBS) or without (CON) g BSS /kg dry matter diet. On day 21 of each period, rumen content samples were obtained at 6 h postfeeding, and blood samples were obtained before morning feeding. The data showed that compared with control group, Dietary BSS supplementation decreased serum concentrations of tumor necrosis factor, interleukin (IL)-6, and IL-1β. The ruminal pH and acetate concentration for BSS treatment were improved, while concentration of propionate, butyrate and lactate was decreased. The result of Illumina MiSeq sequencing of 16S rRNA gene revealed that BSS addition can increase the proportion of Prevotella_1, Rikenellaceae_RC9_gut_group, Prevotella_7, and Selenomonas_1, and decrease the proportion of Lachnospiraceae_NK3A20_group. These results indicated that BSS attenuates high grain diet-induced inflammatory response and modifies ruminal fermentation. In addition, the BSS dietary supplementation at the level of 0.5 g/kg is recommended in sheep.

Potential effects of rapeseed peptide Maillard reaction products on aging-related disorder attenuation and gut microbiota modulation in d-galactose induced aging mice

As a good flavor enhancer, rapeseed peptide Maillard reaction products (MRPs) were developed, and the effects of MRPs on d-galactose induced aging Kunming mice were investigated for 6 weeks with low (200 mg kg-1 day-1), medium (400 mg kg-1 day-1) and high (800 mg kg-1 day-1) doses. Compared with the natural aging group and d-galactose induced aging mice, the mice with MRP administration showed increases in body weight gain, food intake, organ indexes, feces color and urine fluorescence intensity. MRP intake significantly decreased the MDA content and elevated the activities of CAT, SOD and GSH-Px, and T-AOC in the serum and tissues of the liver, kidney and brain. Additionally, AChE activity was decreased in the brain, while Na+-K+ ATPase and Ca2+-Mg2+ ATPase activity increased in a dose-dependent manner, and decreasing levels of IL-1β, IL-6 and TNF-α were observed in the liver and kidney. Histopathological analysis suggested an attenuation of inflammatory cell infiltration in the liver and kidney without cell necrosis. High-throughput sequencing results revealed that the ratio of Firmicutes to Bacteroidetes increased in MRP groups, and the pathogenic bacteria were significantly inhibited, while some beneficial bacteria were significantly increased in the intestine. Overall, our results indicated that MRP consumption might have potential beneficial effects on postponing the aging process via reducing the oxidative stress and gut microflora modulation.