High-sugar and carrageenan-containing diets synergistically impair the intestinal mucosal barrier through the gut microbiota: in vitro and in vivo studies.

BackgroundA high-fat diet (HFD) induced perturbation of gut microbiota is a major contributory factor to promote the pathophysiology of HFD-associated metabolic syndrome. The HFD could also increase the susceptibility to the microbial infections warranting the use of antibiotics which are independently capable of impacting both gut microbiota and metabolic syndrome. Further, the usage of antibiotics in individuals consuming HFD can impact mitochondrial function that can be associated with an elevated risk of chronic conditions like inflammatory bowel disease (IBD). Despite this high propensity to infections in individuals on HFD, the link between duration of HFD and antibiotic treatment, and its impact on diversity of the gut microbiome and features of metabolic syndrome is not well established. In this study, we have addressed these knowledge gaps by examining how the gut microbiota profile changes in HFD-fed mice receiving antibiotic intervention in the form of amoxicillin. We also determine whether antibiotic treatment in HFD-fed mice may adversely impact the ability of immune cells to clear microbial infections.Methods and ResultsWe have subjected mice to HFD and chow diet (CD) for 3 weeks, and a subset of these mice on both diets received antibiotic intervention in the form of amoxicillin in the 3rd week. Body weight and food intake were recorded for 3 weeks. After 21 days, all animals were weighted and sacrificed. Subsequently, these animals were evaluated for basic haemato-biochemical and histopathological attributes. We used 16S rRNA sequencing followed by bioinformatics analysis to determine changes in gut microbiota in these mice. We observed that a HFD, even for a short-duration, could successfully induce the partial pathophysiology typical of a metabolic syndrome, and substantially modulated the gut microbiota in mice. The short course of amoxicillin treatment to HFD-fed mice resulted in beneficial effects by significantly reducing fasting blood glucose and skewing the number of thrombocytes towards a normal range. Remarkably, we observed a significant remodelling of gut microbiota in amoxicillin-treated HFD-fed mice. Importantly, some gut microbes associated with improved insulin sensitivity and recovery from metabolic syndrome only appeared in amoxicillin-treated HFD-fed mice reinforcing the beneficial effects of antibiotic treatment in the HFD-associated metabolic syndrome. Moreover, we also observed the presence of gut-microbiota unique to amoxicillin-treated HFD-fed mice that are also known to improve the pathophysiology associated with metabolic syndrome. However, both CD-fed as well as HFD-fed mice receiving antibiotics showed an increase in intestinal pathogens as is typically observed for antibiotic treatment. Importantly though, infection studies with S. aureus and A. baumannii, revealed that macrophages isolated from amoxicillin-treated HFD-fed mice are comparable to those isolated from mice receiving only HFD or CD in terms of susceptibility, and progression of microbial infection. This finding clearly indicated that amoxicillin treatment does not introduce any additional deficits in the ability of macrophages to combat microbial infections.ConclusionsOur results showed that amoxicillin treatment in HFD-fed mice exert a beneficial influence on the pathophysiological attributes of metabolic syndrome which correlates with a significant remodelling of gut microbiota. A novel observation was the increase in microbes known to improve insulin sensitivity following amoxicillin treatment during short-term intake of HFD. Even though there is a minor increase in gut-resistant intestinal pathogens in amoxicillin-treated groups, there is no adverse impact on macrophages with respect to their susceptibility and ability to control infections. Taken together, this study provides a proof of principle for the exploration of amoxicillin treatment as a potential therapy in the people affected with metabolic syndrome.

Endometriosis (EMS) is a chronic inflammatory disease with unclear pathogenesis. Three studies have uncovered the influence of gut microbiota on mice with EMS, but no study has investigated the characteristics of fecal metabolomics to determine some important clues on EMS. This research aims to uncover the interaction between fecal metabolomics and gut microbiota in EMS mice. Female C57BL/6J mice were used to construct the EMS model. Non-target metabolomics was applied to detect the fecal metabolites of EMS mice. The 16s rRNA sequencing was used for clarifying the composition of the gut microbiota. The functional characteristics of gut microbiota were analyzed using the PICRUSt. The receiver operator characteristic curve (ROC) analysis was utilized for determining the potential important differential metabolites, and the Spearman correlation coefficient was applied for expressing the correlation between the important differential metabolites and gut microbiota. A total of 156 named differential metabolites were screened. The diversity and the abundance of gut microbiota in EMS mice decreased. Eleven pathways were involved in the differential metabolites and the functional prediction of gut microbiota, among which the second bile acid biosynthesis and alpha-linolenic acid (ALA) metabolism were the significant enrichment pathways. The increased abundance of chenodeoxycholic and ursodeoxycholic acids and the decreased abundance of ALA and 12,13-EOTrE were found in the feces of EMS mice. The abnormal fecal metabolites, which are influenced by dysbacteriosis, may be the characteristics of EMS mice and can be the potential important indices to distinguish the disease.

Hypertension-Mediated Gut Microbiota Changed Exacerbate Oxidative Phosphorylation and Fatty Acid Metabolism in the Colon

Tripartite motif-containing protein 31 (TRIM31), an E3 ubiquitin ligase of the tripartite motif family, plays an important role in the innate immune response. It can reduce the activity of the nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome. However, little information is about glucose metabolic health of TRIM31-deficient mice, and investigations about gut microbiota in TRIM31-deficient mice is limited. Thus, we aimed to compare glucose metabolic parameters, gut microbiota composition and inflammatory cytokine levels between TRIM31−/− and wild-type (WT) mice, and further investigate whether or not certain gut microbiota taxon correlates with specific metabolic parameters and inflammation cytokines in TRIM31-deficient mice. TRIM31−/− mice showed glucose intolerance and insulin resistance, with a significant difference in gut microbiota composition, characterized by increased abundance of Prevotellaceae and Veillonellaceae. TRIM31−/− mice with impaired glucose metabolism was accompanied by elevated serum tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) concentrations, as well as upregulated caecal TNF-α, IL-1β, caspase-1, and NLRP3 expressions. Furthermore, elevated p-IRS-1/IRS-1 protein expression, and decreased Akt Thr308 phosphorylation were observed in TRIM31−/− mice. Prevotellaceae abundance was positively associated with caecal IL-1β mRNA expression, and Veillonellaceae was associated with higher TNF-α mRNA expression and serum insulin concentration. In conclusion, our study is novel in showing that TRIM31 deficiency is associated with impaired glucose metabolism and disrupted gut microbiota in mice. This study contributes to the theoretical foundation on the potential relationship between TRIM31 deficiency and the development of abnormal glucose metabolism.

Accumulating evidence indicated that gut microbiota play important roles in the pathogenesis of colitis, and microbiota composition could be modulated by dietary components. Therefore, ameliorating colitis‐associated bacterial dysbiosis by dietary components may be a unique strategy to improve gut health. Herein, we determined the effects of resveratrol on gut microbiota and their implication in anti‐colonic inflammation in mice with colitis induced by dextran sodium sulfate (DSS). Our results showed that DSS treatment dramatically disturbed the composition of gut microbiota in mice, which was associated with elevated colonic inflammation. Dietary treatment with resveratrol partially attenuated the gut microbiota dysbiosis induced by DSS, for example, resveratrol effectively reduced the abundance of bacteria from Verrucomicrobia and Proteobacteria phyla, decreased the abundance of Sutterella and Bilophila genera, and increased the abundance of Bifidobacterium and Lactobacillus genera in DSS‐treated mice. Alpha and beta‐diversity analysis showed that DSS treatment reduced the microbial diversity and shifted the microbial community structure in comparison with the negative control (healthy) mice, while resveratrol ameliorated the aforementioned alteration and restored the diversity of the gut microbiota in DSS‐treated mice. Furthermore, resveratrol alleviated the symptoms of colitis and decreased the expression levels of pro‐inflammatory cytokines such as IL‐10, IL‐2, GM‐CSF, IL‐1β, IL‐6 and TNF‐α, in the colon of DSS‐treated mice. Overall, our data demonstrated that resveratrol partially reversed bacterial dysbiosis in DSS‐treated mice, which may play an important role in its anti‐colitis effect.Support or Funding InformationThis study was partially supported by fund from USDA

BackgroundObesity has become a global epidemic recognized by the World Health Organization. Probiotics supplementation has been shown to contribute to improve lipid metabolism. However, mechanisms of action of probiotics against obesity are still not clear. Lactobacillus plantarum FRT4, a probiotic previously isolated from a kind of local yogurt, had good acid and bile salt tolerance and lowered cholesterol in vitro.ObjectiveThis study aimed to evaluate the effect of L. plantarum FRT4 on serum and liver lipid profile, liver metabolomics, and gut microbiota in mice fed with a high-fat diet (HFD).DesignMice were fed with either normal diet or HFD for 16 weeks and administered 0.2 mL of 1 × 109 or 1 × 1010 CFU/mL dosage of L. plantarum FRT4 during the last 8 weeks of the diet. Cecal contents were analyzed by 16S rRNA sequencing. Hepatic gene expression and metabolites were detected by real-time quantitative polymerase chain reaction (PCR) and metabolomics, respectively.ResultsL. plantarum FRT4 intervention significantly reduced the HFD-induced body weight gain, liver weight, fat weight, serum cholesterol, triglyceride, and alanine aminotransferase (ALT) levels in the liver (P < 0.05). Liver metabolomics demonstrated that the HFD increased choline, glycerophosphocholine, and phosphorylcholine involved in the glycerophospholipid metabolism pathway. All these changes were reversed by FRT4 treatment, bringing the levels close to those in the control group. Further mechanisms showed that FRT4 favorably regulated gut barrier function and pro-inflammatory biomediators. Furthermore, FRT4 intervention altered the gut microbiota profiles and increased microbial diversity. The relative abundances of Bacteroides, Parabateroides, Anaerotruncus, Alistipes, Intestinimonas, Butyicicoccus, and Butyricimonas were significantly upregulated. Finally, Spearman’s correlation analysis revealed that several specific genera were strongly correlated with glycerophospholipid metabolites (P < 0.05).ConclusionsThese findings suggested that L. plantarum FRT4 had beneficial effects against obesity in HFD-induced obese mice and can be used as a potential functional food for the prevention of obesity.

Vaccinium bracteatum Thunb. fruits have been used as traditional food. This study investigated the effects of a polyphenol-rich Vaccinium bracteatum Thunb. fruit extract (VBTE) on obesity and obesity-related diseases in mice, and the potential role of the gut microbiota in the bioactivity of VBTE was also determined. Chemical constituents of the VBTE were analyzed by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS). C57BL/6J mice (weighing 17.8-21.6g) were fed a low-fat diet (LFD) or high-fat diet (HFD) with or without VBTE treatment for 14weeks. The gut microbial changes were determined using 16S rRNA sequencing. Our results showed that VBTE mainly contains 36 kinds of polyphenols. VBTE reduced HFD-induced body weight gain by 33.42% (p<.05), steatosis scores by 56.25% (p<.05), and insulin resistance index by 51.49% (p<.05). Moreover, VBTE altered the composition of the gut microbiota. The correlation analysis indicated that Akkermansia, Alistipes, Bacteroides, Alloprevotella, Ruminiclostridium, Ruminiclostridium_9, and Rikenellaceae_RC9_gut_group were negatively correlated with serum lipids, glucose, and insulin, while Escherichia-Shigella was positively associated with these clinical indicators. In conclusion, VBTE supplement could reduce obesity and be a treatment option for obesity-related diseases by influencing the gut microbiota in mice. PRACTICAL APPLICATIONS: Plant extracts are widely used to treat obesity and related metabolic disorders. Polyphenols, the well-known natural antioxidants present in fruits, are consumed as a dietary supplement to prevent many diseases. Recent pharmacological studies have reported that Vaccinium bracteatum Thunb. fruits have many physiological functions, such as anti-proliferative, anti-inflammatory, and antidepressant-like effects. Despite these properties of Vaccinium bracteatum Thunb. fruits, their anti-obesity effect has not been studied to date. The findings of this study will support VBTE could be used as an important therapeutic application for preventing obesity and related metabolic diseases by modulating the gut microbiota.

The purpose of this study was to explore how semaglutide, a GLP-1RA, regulates serum metabolism and gut microbiota to improve obesity in mice and whether fecal microbiota transplantation (FMT) can transmit the beneficial effects of semaglutide to recipient mice. Male C57BL/6J mice were given standard diet (ND), high-fat diet (HFD), or high-fat diet with semaglutide (SHF, 100μg/kg). Fecal microbiota transplantation was used to transplant the fecal suspension supernatant (MT) and bacteria (FMT) from SHF group mice to antibiotic-induced pseudo-germ-free mice. Results showed that semaglutide significantly reduced the body weight, body fat, FBG, and insulin levels induced by high-fat diet, and improved insulin resistance and sensitivity damage (p < 0.05). This was achieved by regulating the expression of genes related to lipid metabolism such as Pparα, Pparγ, Cpt1a, and Pgc1α in the liver and adipose tissue, as well as the appetite-related genes Leptin, Agrp, Npy, and Pomc in the hypothalamus. After stopping semaglutide intervention 4weeks, the body weight of the mice rebounded significantly. Fecal microbiota transplantation could transmit the beneficial effects of semaglutide to recipient mice. Semaglutide and fecal microbiota transplantation affected metabolic pathways such as serum amino acid metabolism and pyrimidine metabolism in obese mice, and reshaped the composition and proportion of fecal gut microbiota in obese mice. In summary, semaglutide could inhibit food intake and improve obesity, regulate serum metabolism and the composition of gut microbiota in mice. Bacterial transplantation is key to transmitting the improvement brought about by fecal microbiota transplantation of semaglutide to recipient mice.

Purified C. pilosula polysaccharides attenuate streptozotocin-induced oxidative stress and restore gut microbiota in T2DM mice.

Allergic rhinitis (AR) is an allergic condition of the upper respiratory tract with a complex pathogenesis, including epithelial barrier disruption, immune regulation, and gut microbiota, which is not yet fully understood. Gut microbiota is closely linked to allergic diseases, including AR. Fecal microbiota transplantation (FMT) has recently been recognized as a potentially effective therapy for allergic diseases. However, the efficacy and mechanism of action of FMT in AR remain unknown. Herein, we aimed to observe the implications of gut microbiota on epithelial barrier function and T cell homeostasis, as well as the effect of FMT in AR, using the ovalbumin (OVA)-induced AR mice. The intestinal microbiota of recipient mice was cleared using an antibiotic cocktail; thereafter, FMT was performed. Subsequently, the nasal symptom scores and histopathological features of colon and nasal mucosa tissues of mice were monitored, and serum OVA-sIgE and cytokines of IL-4, IFNγ, IL-17A, and IL-10 cytokine concentrations were examined. Thereafter, tight junction protein and CD4+ T cell-related transcription factor and cytokine expressions were observed in the colon and nasal mucosa, and changes in the expression of PI3K/AKT/mTOR and NFκB signaling pathway were detected by WB assay in each group. Fecal DNA was extracted from the four mice groups for high-throughput 16S rRNA sequencing. FMT ameliorated nasal symptoms and reduced nasal mucosal inflammation in AR mice. Moreover, according to 16S rRNA sequencing, FMT restored the disordered gut microbiota in AR mice. Following FMT, ZO-1 and claudin-1 and Th1/Th2/Th17-related transcription factor and cytokine expressions were upregulated, whereas Treg cell-related Foxp3 and IL-10 expressions were downregulated. Mechanistic studies have revealed that FMT also inhibited PI3K/AKT/mTOR and NF-κB pathway protein phosphorylation in AR mouse tissues. FMT alleviates allergic inflammation in AR by repairing the epithelial barrier and modulating CD4+ T cell balance and exerts anti-inflammatory effects through the PI3K/AKT/mTOR and NF-κB signaling pathways. Moreover, gut microbiota disorders are involved in AR pathogenesis. Disturbed gut microbiota causes an altered immune-inflammatory state in mice and increases susceptibility to AR. This study suggested the regulatory role of the gut-nose axis in the pathogenesis of AR is an emerging field, which provides novel directions and ideas for the treatment of AR.

Dysregulated lipid metabolism is a key pathology in metabolic diseases and the liver is a critical organ for lipid metabolism. The gut microbiota has been shown to regulate hepatic lipid metabolism in the host. However, the underlying mechanism by which the gut microbiota influences hepatic lipid metabolism has not been elucidated. Here, a gut microbiota depletion mouse model was constructed with an antibiotics cocktail (Abx) to study the mechanism through which intestinal microbiota regulates hepatic lipid metabolism in high-fat diet (HFD)-fed mice. Our results showed that the Abx treatment effectively eradicated the gut microbiota in these mice. Microbiota depletion reduced the body weight and fat deposition both in white adipose tissue and liver. In addition, microbiota depletion reduced serum levels of glucose, total cholesterol (TC), low-density lipoproteins (LDL), insulin, and leptin in HFD-fed mice. Importantly, the depletion of gut microbiota in HFD-fed mice inhibited excessive hepatic lipid accumulation. Mechanistically, RNA-seq results revealed that gut microbiota depletion changed the expression of hepatic genes involved in cholesterol and fatty acid metabolism, such as Cd36, Mogat1, Cyp39a1, Abcc3, and Gpat3. Moreover, gut microbiota depletion reduced the abundance of bacteria associated with abnormal metabolism and inflammation, including Lachnospiraceae, Coriobacteriaceae_UCG-002, Enterorhabdus, Faecalibaculum, and Desulfovibrio. Correlation analysis showed that there was strong association between the altered gut microbiota abundance and the serum cholesterol level. This study indicates that gut microbiota ameliorates HFD-induced hepatic lipid metabolic dysfunction, which might be associated with genes participating in cholesterol and fatty acid metabolism in the liver.

It has been reported that fermented products (FPs) prepared from sweet potato-shochu distillery by-product suppressed weight gain and decreased serum cholesterol levels in mice under normal dietary conditions. Furthermore, from the information gained from the above data regarding health benefits of the FPs, the aim of this study was evaluating the effects of dietary FPs on lipid accumulation and gut microbiota in mice with or without cholesterol-load in the diet. C57BL/6N mice were fed normal (CO) diet, CO with 10% FPs (CO + FPs) diet, cholesterol loaded (HC) diet, or HC with 10% FPs (HC + FPs) diet for 8 weeks. The mice were then euthanized, and blood samples, tissue samples, and feces were collected. The adipose tissue weight and liver triglyceride levels in the HC + FPs diet groups were significantly reduced compared to that in the HC diet groups. However, FPs significantly increased the serum non-high-density lipoprotein cholesterol (HDL-C) levels, the ratio of non-HDL-C to HDL-C and hepatic total cholesterol levels in mice fed cholesterol-loaded diet compared with that of the HC diet group. Since dietary FPs significantly decreased the protein expression levels of cholesterol 7 alpha-hydroxylase 1 in the HC + FPs diet groups, the cholesterol accumulation in FPs group may be explained by insufficient catabolism from cholesterol to bile acid. In addition, the dietary FPs tended to increase Clostridium cluster IV and XIVa, which are butyrate-producing bacteria. Related to the result, n-butyrate was significantly increased in the CO + FPs and the HC + FPs diet groups compared to their respective control groups. These findings suggested that dietary FPs modulated the lipid pool and gut microbiota.

Vitamin E alpha- and gamma-tocopherol mitigate colitis, protect intestinal barrier function and modulate the gut microbiota in mice

Although dietary fiber treatment alters the gut microbiota and its metabolite production, it is unclear whether or not exercise habits can have a supplemental effect on changes in gut microbiota in dietary fiber-treated mice. To clarify the supplemental effect of voluntary exercise on gut microbiota in partially hydrolyzed guar gum (PHGG), which is a soluble dietary fiber, treated mice under high-fat diet (HFD) feeding, 4-week-old male C57BL/6J mice (n = 80) were randomly divided into two dietary groups: the control-diet (CD) and HFD. Then, each dietary group was treated with or without PHGG, and with or without wheel running. After the experimental period, measurement of maximal oxygen consumption, a glucose tolerance test and fecal materials collection for analysis of gut microbiota were carried out. Voluntary exercise load in PHGG treatment under HFD feeding showed the supplemental effect of exercise on obesity (p < 0.01) and glucose tolerance (p < 0.01). Additionally, in both CD and HFD groups, voluntary exercise accelerated the decrease in the Firmicutes/Bacteroidetes ratio in mice fed with PHGG (p < 0.01). These findings suggest that voluntary exercise might activate the prevention of obesity and insulin resistance more via change in gut microbiota in mice administrated with PHGG.

BackgroundIt has recently been reported that intermittent fasting shapes the gut microbiota to benefit health, but this effect may be influenced to the exact fasting protocols. The purpose of this study was to assess the effects of different daily fasting hours on shaping the gut microbiota in mice. Healthy C57BL/6 J male mice were subjected to 12, 16 or 20 h fasting per day for 1 month, and then fed ad libitum for an extended month. Gut microbiota was analyzed by 16S rRNA gene-based sequencing and food intake was recorded as well.ResultsWe found that cumulative food intake was not changed in the group with 12 h daily fasting, but significantly decreased in the 16 and 20 h fasting groups. The composition of gut microbiota was altered by all these types of intermittent fasting. At genus level, 16 h fasting led to increased level of Akkermansia and decreased level of Alistipes, but these effects disappeared after the cessation of fasting. No taxonomic differences were identified in the other two groups.ConclusionsThese data indicated that intermittent fasting shapes gut microbiota in healthy mice, and the length of daily fasting interval may influence the outcome of intermittent fasting.