Grape Pomace as a Cardiometabolic Health-Promoting Ingredient: Activity in the Intestinal Environment

Grape pomace (GP) is a winemaking by-product particularly rich in (poly)phenols and dietary fiber, which are the main active compounds responsible for its health-promoting effects. These components and their metabolites generated at the intestinal level have been shown to play an important role in promoting health locally and systemically. This review focuses on the potential bioactivities of GP in the intestinal environment, which is the primary site of interaction for food components and their biological activities. These mechanisms include (i) regulation of nutrient digestion and absorption (GP has been shown to inhibit enzymes such as α-amylase and α-glucosidase, protease, and lipase, which can help to reduce blood glucose and lipid levels, and to modulate the expression of intestinal transporters, which can also help to regulate nutrient absorption); (ii) modulation of gut hormone levels and satiety (GP stimulates GLP-1, PYY, CCK, ghrelin, and GIP release, which can help to regulate appetite and satiety); (iii) reinforcement of gut morphology (including the crypt-villi structures, which can improve nutrient absorption and protect against intestinal damage); (iv) protection of intestinal barrier integrity (through tight junctions and paracellular transport); (v) modulation of inflammation and oxidative stress triggered by NF-kB and Nrf2 signaling pathways; and (vi) impact on gut microbiota composition and functionality (leading to increased production of SCFAs and decreased production of LPS). The overall effect of GP within the gut environment reinforces the intestinal function as the first line of defense against multiple disorders, including those impacting cardiometabolic health. Future research on GP's health-promoting properties should consider connections between the gut and other organs, including the gut-heart axis, gut-brain axis, gut-skin axis, and oral-gut axis. Further exploration of these connections, including more human studies, will solidify GP's role as a cardiometabolic health-promoting ingredient and contribute to the prevention and management of cardiovascular diseases.

Resistant Maltodextrin Suppresses Intestinal Phenols Production by Modifying the Intestinal Environment

Protein is an essential nutrient that plays several roles in the maintenance of the human body. A high-protein diet is also known to play an important role in weight management in obese individuals and in maintaining muscle strength in the elderly. However, over-consumption of protein can have negative effects on health, including deterioration of the intestinal environment by the production of amino acid metabolites such as phenols. Interest in the regulation of the intestinal environment to maintain health has gained attention recently. Resistant maltodextrin (RMD) is a prebiotic dietary fiber. Therefore, we investigated whether RMD suppressed the production of amino acid metabolites through intestinal regulation in rats. Wistar rats were fed either an AIN-93G diet or a modified AIN-93G diet containing 5% tyrosine. RMD (2.5% or 5.0%) was provided with drinking water. The rats were fed these diets and water ad libitum for 3 wk. Urine was collected overnight, after which serum, liver, kidneys, and the whole cecum were collected from rats under anesthesia with isoflurane for analysis of phenols and microbiota. RMD decreased the cecal, serum, and urinary levels of phenols, especially phenol. Moreover, the relative abundance of intestinal Romboutsia ilealis showed a significant correlation with the cecal phenols levels, and RMD decreased the abundance of this species. Thus, RMD may suppress phenols production and decrease serum phenols levels by altering the intestinal environment in rats.

Combination of poly-γ-glutamic acid and galactooligosaccharide improves intestinal microbiota, defecation status, and relaxed mood in humans: a randomized, double-blind, parallel-group comparison trial

The genus Bifidobacterium comprises beneficial intestinal bacteria that play a crucial role in the regulation of human health. Traditional prebiotics are known to increase intestinal bifidobacteria by supplying a carbon source necessary for their growth. However, intestinal bifidobacteria need not only a carbon source but also a nitrogen source for growth. Moreover, the growth of bifidobacteria is known to be inhibited in a culture medium that does not contain glutamic acid. Based on these reports, we hypothesized that the combined intake of traditional prebiotics and glutamic acid would be beneficial for growth of bifidobacteria in the gut. In this study, we investigated the effects of the combination of galactooligosaccharide (GOS; traditional prebiotic material) and poly-γ-glutamic acid (γ-PGA; source of glutamic acid) and only GOS on the intestinal microbiota and health conditions (including intestinal regulation, mood status, gastrointestinal condition, skin condition, and sleep quality) in a randomized, double-blind, parallel-group comparison trial in healthy subjects. The combined intake of GOS and γ-PGA significantly increased the prevalence of B. longum compared to the intake of GOS alone. A minimum effective dose of 2.0 g GOS and 0.3 g γ-PGA improved defecation and mood status. We revealed the combined effects of GOS and γ-PGA on intestinal microbiota as well as physical condition and concluded that the delivery of glutamic acid to the large intestine with traditional prebiotics is useful as an advanced prebiotic.

Effects of Pesticide Intake on Gut Microbiota and Metabolites in Healthy Adults

Animal experiments have indicated that pesticides may affect gut microbiota, which is responsible for the production of short-chain fatty acids (SCFAs) and polyamines. Here, we present a preliminary observation of the relationship between pesticide exposure and fecal SCFAs and polyamines in Japanese adults. In total, 38 healthy adults aged 69 ± 10 years (mean ± SD) were recruited and subjected to stool and spot urine tests. Urinary dialkylphosphates (DAP), 3-phenoxybenzoic acid, and glyphosate were assayed as pesticide exposure markers of organophosphorus insecticide (OP), a pyrethroid insecticide, and glyphosate, respectively. Significant negative correlations (p < 0.05, Spearman’s rank correlation coefficient) were found between urinary DAP, fecal acetate (r = −0.345), and lactate (r = −0.391). Multiple regression analyses revealed that urinary DAP was a significant explanatory variable of fecal acetate concentration (p < 0.001, β = −24.0, SE = 4.9, t = −4.9) with some vegetable intake (adjusted R-square = 0.751). These findings suggest that OP exposure is independently associated with lower fecal acetate levels, which may contribute to human health in middle-aged and older adult groups. Given that the human gut environment has long-term effects on the host, studies on wide-range age groups, including children, are necessary.

Dietary Polyphenols Alleviate Autoimmune Liver Disease by Mediating the Intestinal Microenvironment: Challenges and Hopes

Autoimmune liver disease is a chronic liver disease caused by an overactive immune response in the liver that imposes a significant health and economic cost on society. Due to the side effects of existing medicinal medications, there is a trend toward seeking natural bioactive compounds as dietary supplements. Currently, dietary polyphenols have been proven to have the ability to mediate gut-liver immunity and control autoimmune liver disease through modulating the intestinal microenvironment. Based on the preceding, this Review covers the many forms of autoimmune liver illnesses, their pathophysiology, and the modulatory effects of polyphenols on immune disorders. Finally, we focus on how polyphenols interact with the intestinal milieu to improve autoimmune liver disease. In conclusion, we suggest that dietary polyphenols have the potential as gut-targeted modulators for the prevention and treatment of autoimmune liver disease and highlight new perspectives and critical issues for future pharmacological applications.

The Therapeutic Effect of SCFA-Mediated Regulation of the Intestinal Environment on Obesity

Intestinal environment disorder is a potential pathological mechanism of obesity. There is increasing evidence that disorders in the homeostasis of the intestinal environment can affect various metabolic organs, such as fat and liver, and lead to metabolic diseases. However, there are few therapeutic approaches for obesity targeting the intestinal environment. In this review, on the one hand, we discuss how intestinal microbial metabolites SCFA regulate intestinal function to improve obesity and the possible mechanisms and pathways related to obesity-related pathological processes (depending on SCFA-related receptors such as GPCRs, MCT and SMCT, and through epigenetic processes). On the other hand, we discuss dietary management strategies to enrich SCFA-producing bacteria and target specific SCFA-producing bacteria and whether fecal bacteria transplantation therapy to restore the composition of the gut microbiota to regulate SCFA can help prevent or improve obesity. Finally, we believe that it will be of great significance to establish a working model of gut– SCFA– metabolic disease development in the future for the improvement this human health concern.

The Contribution of Dietary Fructose to Non-alcoholic Fatty Liver Disease

Fructose, especially industrial fructose (sucrose and high fructose corn syrup) is commonly used in all kinds of beverages and processed foods. Liver is the primary organ for fructose metabolism, recent studies suggest that excessive fructose intake is a driving force in non-alcoholic fatty liver disease (NAFLD). Dietary fructose metabolism begins at the intestine, along with its metabolites, may influence gut barrier and microbiota community, and contribute to increased nutrient absorption and lipogenic substrates overflow to the liver. Overwhelming fructose and the gut microbiota-derived fructose metabolites (e.g., acetate, butyric acid, butyrate and propionate) trigger the de novo lipogenesis in the liver, and result in lipid accumulation and hepatic steatosis. Fructose also reprograms the metabolic phenotype of liver cells (hepatocytes, macrophages, NK cells, etc.), and induces the occurrence of inflammation in the liver. Besides, there is endogenous fructose production that expands the fructose pool. Considering the close association of fructose metabolism and NAFLD, the drug development that focuses on blocking the absorption and metabolism of fructose might be promising strategies for NAFLD. Here we provide a systematic discussion of the underlying mechanisms of dietary fructose in contributing to the development and progression of NAFLD, and suggest the possible targets to prevent the pathogenetic process.

Psychoactive Effects of Lactobacillus johnsonii Against Restraint Stress-Induced Memory Dysfunction in Mice Through Modulating Intestinal Inflammation and permeability-a Study Based on the Gut-Brain Axis Hypothesis

Though the underlying mechanism remains elusive, a close relationship between psychological stress and intestinal inflammation has been widely accepted. Such a link is very important to set the basis for our understanding of the critical role of gut-brain axis (GBA) in homeostatic processes in health and disease. Probiotics that could confer benefits to mental health through GBA are referred to as "psychobiotics". This study aimed to further determine whether a potential psychobiotic strain, Lactobacillus johnsonii BS15 could prevent memory dysfunction in mice induced by psychological stress through modulating the gut environment, including intestinal inflammation and permeability. Memory dysfunction in mice was induced by restraint stress (RS), one of the most commonly utilized models to mimic psychological stress. The mice were randomly categorized into three groups including no stress (NS), restraint stress (RS), and probiotic (RS-P) and administered with either phosphate buffered saline (NS and RS groups) or L. johnsonii BS15 (RS-P group) every day from day 1-28. From days 22-28, the mice in RS and RS-P groups were subjected to RS each day. Results revealed that BS15-pretreatment enhanced the performance of RS-induced mice during three different behavioral tests for memory ability and positively modulated the hypothalamic-pituitary-adrenal axis by attenuating the serum corticosterone level. In the hippocampus, L. johnsonii BS15 positively modulated the memory-related functional proteins related to synaptic plasticity, increased neurotransmitter levels, and prevented RS-induced oxidative stress and mitochondria-mediated apoptosis. In the intestines, L. johnsonii BS15 protected the RS-induced mice from damaged gut barrier by enhancing the mRNA levels of tight junction proteins and exerted beneficial effects on the anti-inflammatory cytokine levels reduced by RS. These findings provided more evidence to reveal the psychoactive effect of L. johnsonii BS15 against memory dysfunction in RS-induced mice by modulating intestinal inflammation and permeability.

Slight Disruption in Intestinal Environment by Dextran Sodium Sulfate Reduces Egg Yolk Size Through Disfunction of Ovarian Follicle Growth

Intestinal environments such as microbiota, mucosal barrier function, and cytokine production affect egg production in laying hens. Dextran sodium sulfate (DSS) is an agent that disrupts the intestinal environment. Previously, we reported that the oral administration of dextran sodium sulfate (DSS: 0.9 g/kg BW) for 5 days caused severe intestinal inflammation in laying hens. However, the DSS concentration in the previous study was much higher to induce a milder disruption of the intestinal environment without heavy symptoms. Thus, the goal of this study was to determine the effects of a lower dose of DSS on the intestinal environment and egg production in laying hens. White Leghorn laying hens (330-day old) were oral administered with or without 0.225 g DSS/kg BW for 28 days (DSS and control group: n = 7 and 8, respectively). Weekly we collected all laid eggs and blood plasma samples. Intestinal tissues, liver, ovarian follicles, and the anterior pituitary gland were collected 1 day after the final treatment. Lower concentrations of orally administered DSS caused (1) a decrease in the ratio of villus height/crypt depth, occludin gene expressions in large intestine and cecal microbiota diversity, (2) a decrease in egg yolk weight, (3) an increase in VLDLy in blood plasma, (4), and enhanced the egg yolk precursor accumulation in the gene expression pattern in the follicular granulosa layer, (5) an increase in FSH and IL-1β gene expression in the pituitary gland, and (6) an increase in concentration of plasma lipopolysaccharide binding protein. These results suggested that the administration of the lower concentration of DSS caused a slight disruption in the intestinal environment. This disruption included poor intestinal morphology and decreased cecal microbiome diversity. The change in the intestinal environment decreases egg yolk size without decreasing the VLDLy supply from the liver. The decrease in egg yolk size is likely to be caused by the dysfunction of egg-yolk precursor uptake in ovarian follicles. In conclusion, the oral administration of a lower dose of DSS is an useful method to cause slight disruptions of intestinal environment, and the intestinal condition decreases egg yolk size through disfunction of ovarian follicle.

Ingestion of Helianthus tuberosus at Breakfast Rather Than at Dinner Is More Effective for Suppressing Glucose Levels and Improving the Intestinal Microbiota in Older Adults

To date, nutritional studies have focused on the total intake of dietary fiber rather than intake timing. In this study, we examined the effect of the timing of daily Helianthus tuberosus ingestion on postprandial and 24 h glucose levels, as well as on intestinal microbiota in older adults. In total, 37 healthy older adults (age = 74.9 ± 0.8 years) were recruited. The participants were randomly assigned to either a morning group (MG, n = 18) or an evening group (EG, n = 17). The MG and EG groups were instructed to take Helianthus tuberosus powder (5 g/day) just before breakfast or dinner, respectively, for 1 week after the 1-week control period. The glucose levels of all participants were monitored using a continuous glucose monitoring system throughout the 2 weeks. The intestinal microbiota was analyzed by sequencing 16S rRNA genes from feces before and after the intervention. There were no significant differences in the physical characteristics or energy intake between groups. Helianthus tuberosus intake led to decreases in tissue glucose levels throughout the day in both groups (p < 0.01, respectively). As a result of examining the fluctuations in tissue glucose levels up to 4 hours after each meal, significant decreases in the areas under the curves (AUCs) were observed for all three meals after intervention, but only in the MG (breakfast: p = 0.012, lunch: p = 0.002, dinner: p = 0.005). On the other hand, in the EG, there was a strong decrease in the AUC after dinner, but only slight decreases after breakfast and lunch (breakfast: p = 0.017, lunch: p = 0.427, dinner: p = 0.002). Moreover, the rate of change in the peak tissue glucose level at breakfast was significantly decreased in the MG compared to the EG (p = 0.027). A greater decrease was observed in the change in the blood glucose level after the ingestion of Helianthus tuberosus in the MG than in the EG. Furthermore, the relative abundance of Ruminococcus in the MG at the genus level was significantly higher at baseline than in the EG (p = 0.016) and it was also significantly lower after the intervention (p = 0.013). Our findings indicate that Helianthus tuberosus intake in the morning might have relatively stronger effects on the intestinal microbiota and suppress postprandial glucose levels to a greater extent than when taken in the evening.

Adherent-Invasive E. coli: Update on the Lifestyle of a Troublemaker in Crohn's Disease

Besides genetic polymorphisms and environmental factors, the intestinal microbiota is an important factor in the etiology of Crohn's disease (CD). Among microbiota alterations, a particular pathotype of Escherichia coli involved in the pathogenesis of CD abnormally colonizes the intestinal mucosa of patients: the adherent-invasive Escherichia coli (AIEC) pathobiont bacteria, which have the abilities to adhere to and to invade intestinal epithelial cells (IECs), as well as to survive and replicate within macrophages. AIEC have been the subject of many studies in recent years to unveil some genes linked to AIEC virulence and to understand the impact of AIEC infection on the gut and consequently their involvement in CD. In this review, we describe the lifestyle of AIEC bacteria within the intestine, from the interaction with intestinal epithelial and immune cells with an emphasis on environmental and genetic factors favoring their implantation, to their lifestyle in the intestinal lumen. Finally, we discuss AIEC-targeting strategies such as the use of FimH antagonists, bacteriophages, or antibiotics, which could constitute therapeutic options to prevent and limit AIEC colonization in CD patients.

Polyphenols Alleviate Oxidative Stress-Induced Intestinal Environment Imbalance and Lipopolysaccharide-Induced Liver Injury in HFD-Fed Rats by Regulating the Nrf2/HO-1/NQO1 and MAPK Pathways

SCOPE

This study investigates the modulatory effects of Lonicera caerulea L. polyphenols (LCPs) on the intestinal environment and lipopolysaccharide (LPS)-induced liver injury via the nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (HO-1)/NQO1 and mitogen-activated protein kinase (MAPK) pathways in a rat model of oxidative stress damage (OSD).

METHODS AND RESULTS

To examine the prebiotic properties of LCP, a model of high-fat-diet-induced OSD is established using Sprague Dawley rats. In the colon, treatment with LCP for 8 weeks ameliorates enhanced intestinal permeability (glucagon-like peptide-2 content and occludin protein increase, whereas claudin-2 protein decreases), intestinal inflammation (levels of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin-6, cyclooxygenase-2, and nuclear factor kappa-B p65 (NF-κB p65), decrease), and intestinal OSD (through regulation of the Nrf2/HO-1/NQO1 pathway). Moreover, LCP alleviates LPS-induced liver injury by suppressing the nuclear translocation of NF-κB p65 and activation of the MAPK signaling pathway. Additionally, Bacilli, Lactobacillales, Lactobacillaceae, Lactobacillus, Akkermansia, Actinobacteria, Proteobacteria, Rothia, and Blautia are found to be the key intestinal microbial taxa related to intestinal OSD and LPS-induced liver injury in rats.

CONCLUSION

LCP treatment potentially modulates the intestinal environment and alleviates liver injury by suppressing oxidative-stress-related pathways and altering the composition of the intestinal microbiota.

Nod1 and Nod2 signaling does not alter the composition of intestinal bacterial communities at homeostasis

Patients with inflammatory bowel diseases (IBD) harbour intestinal bacterial communities with altered composition compared with healthy counterparts; however, it is unknown whether changes in the microbiota are associated with genetic susceptibility of individuals for developing disease or instead reflect other changes in the intestinal environment related to the disease itself. Since deficiencies in the innate immune receptors Nod1 and Nod2 are linked to IBD, we tested the hypothesis that Nod-signaling alters intestinal immune profiles and subsequently alters bacterial community structure. We used qPCR to analyze expression patterns of selected immune mediators in the ileum and cecum of Nod-deficient mice compared with their Nod-sufficient littermates and assessed the relative abundance of major bacterial groups sampled from the ileum, cecum and colon. The Nod1-deficient ileum exhibited significantly lower expression of Nod2, Muc2, α- and β-defensins and keratinocyte-derived chemokine (KC), suggesting a weakened epithelial barrier compared with WT littermates; however, there were no significant differences in the relative abundance of targeted bacterial groups, indicating that Nod1-associated immune differences alone do not promote dysbiosis. Furthermore, Nod2-deficient mice did not display any changes in the expression of immune markers or bacterial communities. Shifts in bacterial communities that were observed in this study correlated with housing conditions and were independent of genotype. These findings emphasize the importance of using F2 littermate controls to minimize environmental sources of variation in microbial analyses, to establish baseline conditions for host-microbe homeostasis in Nod-deficient mice and to strengthen models for testing factors contributing to microbial dysbiosis associated with IBD.