Metabolites Short-chain Fatty Acids Research Articles

MO099REPROGRAMMING HYPERTENSION PROGRAMMED BY HIGH-FAT DIET: THE ROLE OF GARLIC OIL

Abstract Background and Aims Perinatal high-fat (HF) diet programs high blood pressure (BP) in adult offspring. Hydrogen sulfide (H2S) has shown benefits in hypertension by restoration of nitric oxide (NO) bioavailability and alterations of gut microbiota. Garlic, a naturally dietary source of H2S donors, supplementation has shown benefits in hypertension. We aimed to examine whether maternal garlic oil supplementation can prevent hypertension programmed by maternal and post-weaning high-fat diet in adult offspring and whether its protective effects are related to mediation of H2S-genetaing system, alterations of gut microbiota composition, and microbiota metabolite short chain fatty acids (SCFAs). Method Pregnant rats received either a normal diet (ND) or HF diet (D12331, Research Diets, Inc.) Garlic oil (GO) or vesicle was administered daily by oral gavage at 100 mg/kg/day during pregnancy and lactation. Male offspring were weaned at 3 weeks of age, and onto either ND or HF diet to 16 weeks of age. Male offspring were assigned to four groups (n=8/group): ND, HF, ND+GO, and HF+GO. Garlic supplementation during pregnancy and lactation protected against programmed hypertension in adult male offspring fed with HF diet. All offspring were killed at 16 weeks of age. NO-related parameters were analyzed by HPLC. Plasma levels of SCFA were determined using GC-MS method. Fecal microbial community was analyzed using a combination of 16S rRNA gene and fecal metagenome sequence analysis. Results Garlic supplementation during pregnancy and lactation protected against programmed hypertension in adult male offspring fed with HF diet. Garlic oil supplementation caused a significant increase in plasma levels of acetate, propionate, and butyrate. NO bioavailability was augmented by garlic oil supplementation, represented by decreases of plasma levels of asymmetric and symmetric dimethylarginine (ADMA and SDMA) levels, and increased plasma L-arginine-to-ADMA ratio (AAR). HF intake associated with decreased α-diversity was quantified by Shannon diversity index. The Analysis of similarities (ANOSIM) demonstrated the difference in the gut microbiota among the four groups existed (All p < 0.05), indicating that four groups had distinct enterotypes. Additionally, garlic oil supplementation increased abundance of genus Lactobacillus, but decreased genera Turicibacter and Staphylococcus. Moreover, the linear discriminant analysis effect size (LEfSe) algorithm analysis identified several microbial markers including genera Lactobacillus, Staphylococcus, and Turicibacter. Conclusion The beneficial effects of garlic oil were associated with increased renal mRNA expression and activity of H2S-generating enzymes, increased NO bioavailability, increased plasma SCFA levels, and alterations of gut microbiota composition. Our data revealed associations between H2S-generating pathway in the gut and kidneys, NO system, gut microbiota, and microbiota-derived metabolites in hypertension programmed by HF intake and provided insight to garlic oil as a hypertension reprogramming strategy for further translational research.

Upregulated IL-32 Expression And Reduced Gut Short Chain Fatty Acid Caproic Acid in People Living With HIV With Subclinical Atherosclerosis

Despite the success of antiretroviral therapy (ART), people living with HIV (PLWH) are still at higher risk for cardiovascular diseases (CVDs) that are mediated by chronic inflammation. Identification of novel inflammatory mediators with the inherent potential to be used as CVD biomarkers and also as therapeutic targets is critically needed for better risk stratification and disease management in PLWH. Here, we investigated the expression and potential role of the multi-isoform proinflammatory cytokine IL-32 in subclinical atherosclerosis in PLWH (n=49 with subclinical atherosclerosis and n=30 without) and HIV- controls (n=25 with subclinical atherosclerosis and n=24 without). While expression of all tested IL-32 isoforms (α, β, γ, D, ϵ, and θ) was significantly higher in peripheral blood from PLWH compared to HIV- controls, IL-32D and IL-32θ isoforms were further upregulated in HIV+ individuals with coronary artery atherosclerosis compared to their counterparts without. Upregulation of these two isoforms was associated with increased plasma levels of IL-18 and IL-1β and downregulation of the atheroprotective protein TRAIL, which together composed a unique atherosclerotic inflammatory signature specific for PLWH compared to HIV- controls. Logistic regression analysis demonstrated that modulation of these inflammatory variables was independent of age, smoking, and statin treatment. Furthermore, our in vitro functional data linked IL-32 to macrophage activation and production of IL-18 and downregulation of TRAIL, a mechanism previously shown to be associated with impaired cholesterol metabolism and atherosclerosis. Finally, increased expression of IL-32 isoforms in PLWH with subclinical atherosclerosis was associated with altered gut microbiome (increased pathogenic bacteria; Rothia and Eggerthella species) and lower abundance of the gut metabolite short-chain fatty acid (SCFA) caproic acid, measured in fecal samples from the study participants. Importantly, caproic acid diminished the production of IL-32, IL-18, and IL-1β in human PBMCs in response to bacterial LPS stimulation. In conclusion, our studies identified an HIV-specific atherosclerotic inflammatory signature including specific IL-32 isoforms, which is regulated by the SCFA caproic acid and that may lead to new potential therapies to prevent CVD in ART-treated PLWH.

Mannan oligosaccharide attenuates cognitive and behavioral disorders in the 5xFAD Alzheimer's disease mouse model via regulating the gut microbiota-brain axis

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by cognitive deficits and psychiatric symptoms. The gut microbiota-brain axis plays a pivotal role during AD development, which could target nutritional intervention. The prebiotic mannan oligosaccharide (MOS) has been reported to reshape the gut microbiome and enhanced the formation of the neuroprotective metabolites short-chain fatty acids (SCFAs). Here, we found that an 8-week treatment of MOS (0.12%, w/v in the drinking water) significantly improved cognitive function and spatial memory, accompanied by attenuated the anxiety- and obsessive-like behaviors in the 5xFAD transgenic AD mice model. MOS substantially reduced the Aβ accumulation in the cortex, hippocampus, and amygdala of the brain. Importantly, MOS treatment significantly balanced the brain redox status and suppressed the neuroinflammatory responses. Moreover, MOS also alleviated the HPA-axis disorders by decreasing the levels of hormones corticosterone (CORT) and corticotropin-releasing hormone (CRH) and upregulated the norepinephrine (NE) expressions. Notably, the gut barrier integrity damage and the LPS leak were prevented by the MOS treatment. MOS re-constructed the gut microbiota composition, including increasing the relative abundance of Lactobacillus and reducing the relative abundance of Helicobacter. MOS enhanced the butyrate formation and related microbes levels. The correlation analysis indicated that the reshaped gut microbiome and enhanced butyrate formation are highly associated with behavioral alteration and brain oxidative status. SCFAs supplementation experiment also attenuated the behavioral disorders and Aβ accumulation in the AD mice brain, accompanied by balanced HPA-axis and redox status. In conclusion, the present study indicated that MOS significantly attenuates the cognitive and mental deficits in the 5xFAD mice, which could be partly explained by the reshaped microbiome and enhanced SCFAs formation in the gut. MOS, as a prebiotics, can be translated into a novel microbiota-targeted approach for managing metabolic and neurodegenerative diseases.

Decreased Intestinal Microbiome Diversity in Pediatric Sepsis: A Conceptual Framework for Intestinal Dysbiosis to Influence Immunometabolic Function.

The intestinal microbiome can modulate immune function through production of microbial-derived short-chain fatty acids. We explored whether intestinal dysbiosis in children with sepsis leads to changes in microbial-derived short-chain fatty acids in plasma and stool that are associated with immunometabolic dysfunction in peripheral blood mononuclear cells. Prospective observational pilot study. Single academic PICU. Forty-three children with sepsis/septic shock and 44 healthy controls. Stool and plasma samples were serially collected for sepsis patients; stool was collected once for controls. The intestinal microbiome was assessed using 16S ribosomal RNA sequencing and alpha- and beta-diversity were determined. We measured short-chain fatty acids using liquid chromatography, peripheral blood mononuclear cell mitochondrial respiration using high-resolution respirometry, and immune function using ex vivo lipopolysaccharide-stimulated whole blood tumor necrosis factor-α. Sepsis patients exhibited reduced microbial diversity compared with healthy controls, with lower alpha- and beta-diversity. Reduced microbial diversity among sepsis patients (mainly from lower abundance of commensal obligate anaerobes) was associated with increased acetic and propionic acid and decreased butyric, isobutyric, and caproic acid. Decreased levels of plasma butyric acid were further associated with lower peripheral blood mononuclear cell mitochondrial respiration, which in turn, was associated with lower lipopolysaccharide-stimulated tumor necrosis factor-α. However, neither intestinal dysbiosis nor specific patterns of short-chain fatty acids were associated with lipopolysaccharide-stimulated tumor necrosis factor-α. Intestinal dysbiosis was associated with altered short-chain fatty acid metabolites in children with sepsis, but these findings were not linked directly to mitochondrial or immunologic changes. More detailed mechanistic studies are needed to test the role of microbial-derived short-chain fatty acids in the progression of sepsis.

Exopolysaccharide from Leuconostoc pseudomesenteroides XG5 delay the onset of autoimmune diabetes by modulating gut microbiota and its metabolites SCFAs in NOD mice

• XG5 EPS delay the onset of autoimmune diabetes in NOD mice. • XG5 EPS expanded the Foxp3 + Tregs frequency of the spleen in NOD mice. • XG5 EPS altered the gut microbiota composition. • XG5 EPS increased the short-chain fatty acids levels of colon contents. Exopolysaccharide produced by Leuconostoc pseudomesenteroides XG5 (XG5 EPS) is a potential prebiotic. The study objective is to assess the effect of XG5 EPS on autoimmune diabetes using non-obese diabetic (NOD) mouse strain. Our results indicated that XG5 EPS administration delayed the onset of autoimmune diabetes, reduced the level of diabetogenic cytokines IL-21 and promoted the frequency of Foxp3 + regulatory T cells in NOD mice. Moreover, XG5 EPS altered the gut microbiota composition, especially 50 mg·kg −1 XG5 EPS administration increased the ratio of Firmicutes to Bacteroidetes at the phylum level and the concentrations of total short-chain fatty acids (SCFAs) in NOD mice. Considering that the influence of viscosity on utilization of XG5 EPS, a dose dependent effect was not established. Taken together, oral administration of 50 mg·kg −1 XG5 EPS has a potential to delay the onset of autoimmune diabetes by modulating gut microbiota and its metabolites SCFAs in NOD mice.

The Role of Gut Bacterial Metabolites in Brain Development, Aging and Disease.

In the last decade, emerging evidence has reported correlations between the gut microbiome and human health and disease, including those affecting the brain. We performed a systematic assessment of the available literature focusing on gut bacterial metabolites and their associations with diseases of the central nervous system (CNS). The bacterial metabolites short-chain fatty acids (SCFAs) as well as non-SCFAs like amino acid metabolites (AAMs) and bacterial amyloids are described in particular. We found significantly altered SCFA levels in patients with autism spectrum disorder (ASD), affective disorders, multiple sclerosis (MS) and Parkinson’s disease (PD). Non-SCFAs yielded less significantly distinct changes in faecal levels of patients and healthy controls, with the majority of findings were derived from urinary and blood samples. Preclinical studies have implicated different bacterial metabolites with potentially beneficial as well as detrimental mechanisms in brain diseases. Examples include immunomodulation and changes in catecholamine production by histone deacetylase inhibition, anti-inflammatory effects through activity on the aryl hydrocarbon receptor and involvement in protein misfolding. Overall, our findings highlight the existence of altered bacterial metabolites in patients across various brain diseases, as well as potential neuroactive effects by which gut-derived SCFAs, p-cresol, indole derivatives and bacterial amyloids could impact disease development and progression. The findings summarized in this review could lead to further insights into the gut–brain–axis and thus into potential diagnostic, therapeutic or preventive strategies in brain diseases.

Effect of temperature stress on gut-brain axis in mice: Regulation of intestinal microbiome and central NLRP3 inflammasomes

BackgroundTemperature stress was reported to impact the gut-brain axis including intestinal microbiome and neuroinflammation, but the molecular markers involved remain unclear. We aimed to examine the effects of different temperature stress on the intestinal microbiome and central nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasomes. Materials and methodsMice models were established under low temperature (LT), room temperature (RT), high temperature (HT), and temperature variation (TV) respectively for seven days. We examined temperature-induced changes of intestinal microbiome composition and the levels of its metabolites short-chain fatty acids (SCFAs), as well as the expressions of central NLRP3 inflammasomes and inflammatory cytokines. Redundancy analysis and Spearman correlation analysis were performed to explore the relationships between microbiome and NLRP3 inflammasomes and other indicators. ResultsHT and LT significantly increased the Alpha diversity of intestinal microbiome. Compared with RT group, Bacteroidetes were most abundant in LT group while Actinobacteria were most abundant in HT and TV groups. Nineteen discriminative bacteria were identified among four groups. LT increased the expressions of acetate and propionate while decreased that of NLRP3 inflammasomes; HT decreased the expression of butyrate while increased that of NLRP3 inflammasomes, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α; TV decreased the expression of propionate while increased that of NLRP3 inflammasomes and TNF-α. Microbiome distribution could significantly explain the differences in NLRP3 between comparison groups (LT&RT: R2 = 0.82, HT&RT: R2 = 0.86, TV&RT: R2 = 0.94; P < 0.05). The discriminative bacteria were significantly correlated with SCFAs but were correlated with NLRP3 inflammasomes and cytokines in the opposite direction. ConclusionsLT inhibits while HT and TV promote the activation of NLRP3 inflammasomes in brain, and intestinal microbiome and its metabolites may be the potential mediators. Findings may shed some light on the impact of temperature stress on gut-brain axis.

Short-Chain Fatty Acids Promote Intracellular Bactericidal Activity in Head Kidney Macrophages From Turbot (Scophthalmus maximus L.) via Hypoxia Inducible Factor-1α.

Short-chain fatty acids (SCFAs) are mainly produced by microbiota through the fermentation of carbohydrates in the intestine. Acetate, propionate, and butyrate are the most abundant SCFA metabolites and have been shown to be important in the maintenance of host health. In this study, head kidney macrophages (HKMs) were isolated and cultured from turbots. We found that the antibacterial activity of HKMs was increased after these cells were incubated with sodium butyrate, sodium propionate or sodium acetate. Interestingly, our results showed that all three SCFAs enhanced the expression of hypoxia inducible factor-1 α (HIF-1α) in HKMs, and further study confirmed that butyrate augmented the oxygen consumption of these cells. Moreover, HIF-1α inhibition diminished the butyrate-promoted intracellular bacterial killing activity of macrophages, and SCFAs also raised the gene expression and activity of lysozymes in HKMs via HIF-1α signaling. In addition, our results suggested that butyrate induced HIF-1α expression and the bactericidal activity of HKMs through histone deacetylase inhibition, while G protein-coupled receptors did not contribute to this effect. Finally, we demonstrated that butyrate induced a similar response in the murine macrophage cell line RAW264.7. In conclusion, our results demonstrated that SCFAs promoted HIF-1α expression via histone deacetylase inhibition, leading to the enhanced production of antibacterial effectors and increased bacterial killing of macrophages.

Effects of Dietary Supplementation with Clostridium butyricum on Growth Performance, Serum Immunity, Intestinal Morphology, and Microbiota as an Antibiotic Alternative in Weaned Piglets.

Simple SummaryMany countries have banned the use of antibiotic growth promoters (AGPs), which negatively affect weanling piglets’ growth performance and health. Therefore, it would be valuable to find eco-friendly and non-antibiotic alternatives to AGPs and to evaluate their effects. However, limited information is available on Clostridium butyricum applied in weanling piglets. In this study, the results showed that Clostridium butyricum administration have positive effects on growth performance, immunity, intestinal morphology, and microbial balance. In conclusion, Clostridium butyricum can be used as a potential alternative to AGPs in weanling piglets.This study investigated the effects of Clostridium butyricum (C. butyricum) use on growth performance, serum immunity, intestinal morphology, and microbiota as an antibiotic alternative in weaned piglets. Over the course of 28 days, 120 piglets were allocated to four treatments with six replicates of five piglets each. The treatments were: CON (basal diet); AGP (basal diet supplemented with 0.075 g/kg chlortetracycline, 0.055 g/kg kitasamycin, and 0.01 g/kg virginiamycin); CBN (basal diet supplemented with normal dosage of 2.5 × 108 CFU/kg C. butyricum); and CBH (basal diet supplemented with high dosage of 2.5 × 109 CFU/kg C. butyricum). Body weight (BW) and feed consumption were recorded at the beginning and on days 14 and 28 of the experiment, and representative feed samples and fresh feces were collected from each pen between days 26 and 28. Average fecal score of diarrhea was visually assessed each morning during the experimental period. On the morning of days 14 and 28, blood samples were collected to prepare serum for immune and antioxidant parameters measurement. One male piglet close to the average group BW was selected from each replicate and was slaughtered on day 21 of the experiment. Intestinal crypt villi, and colonic microbiota and its metabolites short-chain fatty acids were measured. Compared to the CON group, the CBN and AGP groups significantly decreased (p < 0.05) the ratio of feed to weight gain by 8.86% and 8.37% between days 1 and 14, 3.96% and 13.36% between days 15 and 28, 5.47% and 11.44% between days 1 and 28. Dietary treatment with C. butyricum and AGPs significantly decreased the average fecal score during the experimental period (p < 0.05). The apparent total tract digestibility of dry matter, organic matter, and total carbohydrates in the CBH group were higher respectively at 3.27%, 2.90%, and 2.97%, than those in the CON or AGP groups (p < 0.05). Compared to the CON group, the CBH group significantly increased short-chain fatty acids in colon and villus height in the jejunum (p < 0.05). The CBN group had higher serum levels of immunoglobulins, interleukin 2 (IL-2), and glutathione peroxidase (GSH-PX) activity, but lower serum levels of IL-1β and IL-6, and a lower aspartate aminotransferase (AST), alkaline phosphatase (ALP), and gamma-glutamyl transpeptidase (γ-GT) activity (p < 0.05), while compared to the CON group. Dietary treatment with C. butyricum significantly increased the relative abundance of Streptococcus and Bifidobacterium (p < 0.05). In summary, diet with C. butyricum increased the growth performance and benefited the health of weaned piglets.

High-Dietary Fiber Intake Alleviates Antenatal Obesity-Induced Postpartum Depression: Roles of Gut Microbiota and Microbial Metabolite Short-chain Fatty Acid Involved.

Antenatal obesity increases the risk of postpartum depression. Previous research found that dietary fiber supplementation could alleviate mental behavioral disorders. The present study aims to uncover the effects of high-dietary fiber intake on high-fat diet (HFD)-induced depressive-like behaviors and its underlying mechanism. Female C57BL6/J mice were fed with HFD to establish an antenatal obese model. A high-dietary fiber intake (inulin, 0.037 g/kcal) significantly attenuated cognitive deficits and depressive-like behaviors in the maternal mice after the offspring weaning. High-dietary fiber intake upregulated the expression of 5-hydroxytryptamine (5-HT) and norepinephrine (NE) and suppressed neuroinflammation. Furthermore, high-dietary fiber intake restructured the gut microbiome and elevated the formation of short-chain fatty acids (SCFAs). Correlation analysis indicated that the increase in microbes such as Lactobacillus and S24-7, and SCFAs' levels were positively correlated with behavioral improvements. In conclusion, high-dietary fiber intake is a promising nutritional intervention strategy to prevent antenatal obesity-induced behavioral disorders via a microbiota-gut-brain axis.

Puerarin improves the bone micro-environment to inhibit OVX-induced osteoporosis via modulating SCFAs released by the gut microbiota and repairing intestinal mucosal integrity

ScopeHalf of women over the age of 50 will experience a fracture related osteoporosis in their lifetime. The common treatment is estrogen replacement therapy, which can cause many side effects. Puerarin as a phytoestrogen has been proven to improve postmenopausal osteoporosis. However, the mechanisms of anti-osteoporosis remain unclear due to its low bioavailability. The aim of this study is to investigate whether the anti-osteoporosis effects of puerarin are related to modulations in the gut microbiota and focus on the mechanism of gut / bone axis. MethodsWe established ovariectomized (OVX) rats as osteoporosis model. The femur was analyzed by microcomputed tomography (μ-CT) and we measured serum biochemical indices and inflammatory factors. 16S rRNA sequencing was employed to evaluate the gut microbiota composition in the fecal samples. Short-chain fatty acids (SCFAs) was analyzed by GC. The expression of intestinal inflammatory factors and adhesion proteins was confirmed by western blotting and qPCR. ResultsPuerarin increased the BMD and improved the intestinal mucosal integrity to reduce the systemic inflammation. The disorder of gut microbiota was improved and its metabolites SCFAs were elevated. Metabolic pathways such as amino acid metabolism, LPS biosynthesis and butyrate metabolism were enriched. ConclusionPuerarin treatment modulated the gut microbiota disorder to elicit the anti-osteoporosis effects in OVX rats, by improving the bone micro-environment via regulating the SCFAs levels and repairing the intestinal mucosal integrity.

Butyrate Rescues Oxidative Stress-Induced Transport Deficits of Tryptophan: Potential Implication in Affective or Gut-Brain Axis Disorders

Introduction: Butyrate is a short-chain fatty acid metabolite produced by microbiota in the colon. With its antioxidant properties, butyrate has also been shown to alter the neurological functions in affective disorder models, suggesting it as a key mediator in gut-brain interactions. Objective: Here, we evaluated the negative effect of oxidative stress on the transport of the serotonin precursor tryptophan as present in affective disorders. Butyrate was hypothesized to be able to rescue these deficits due to its antioxidative capacities and its effect on transmembrane transport of tryptophan. Human skin-derived fibroblasts were used as cellular models to address these objectives. Methods: Human fibroblasts were treated with hydrogen peroxide to induce oxidative stress. Stressed as well as control cells were treated with different concentrations of butyrate. Tryptophan (3H) was used as a tracer to measure the transport of tryptophan across the cell membranes (n = 6). Furthermore, gene expression profiles of different amino acid transporters were analyzed (n = 2). Results: As hypothesized,oxidative stress significantly decreased the uptake of tryptophan in fibroblast cells, while butyrate counteracted this effect. Oxidative stress did not alter the gene expression profile of amino acid transporters. However, treatment of stressed and control cells with different concentrations of butyrate differentially regulated the gene expression of large amino acid transporters 1 and 2, which are the major transporters of tryptophan. Conclusions:Gut microbiota-derived butyrate may have therapeutic potential in affective disorders characterized by either aberrant serotonergic activity or neuroinflammation due to its role in rescuing the oxidative stress-induced perturbations of tryptophan transport.

Daily Fermented Whey Consumption Alters the Fecal Short-Chain Fatty Acid Profile in Healthy Adults.

Gut microbiota influences many aspects of host health including immune, metabolic, and gut health. We examined the effect of a fermented whey concentrate (FWC) drink rich in L-(+)-Lactic acid, consumed daily, in 18 healthy men (n = 5) and women (n = 13) in free-living conditions.Objective: The aims of this 6-weeks pilot trial were to (i) identify changes in the gut microbiota composition and fecal short chain fatty acid (SCFA) profile, and (ii) to monitor changes in glucose homeostasis.Results: Total fecal SCFA (mM) concentration remained constant throughout the intervention. Proportionally, there was a significant change in the composition of different SCFAs compared to baseline. Acetate levels were significantly reduced (−6.5%; p < 0.01), coupled to a significant increase in the relative amounts of propionate (+2.2%; p < 0.01) and butyrate (+4.2%; p < 0.01), respectively. No changes in the relative abundance of any specific bacteria were detected. No significant changes were observed in glucose homeostasis in response to an oral glucose tolerance test.Conclusion: Daily consumption of a fermented whey product led to significant changes in fecal SCFA metabolite profile, indicating some potential prebiotic activity. These changes did not result in any detectable differences in microbiota composition. Post-hoc analysis indicated that baseline microbiota composition might be indicative of participants likely to see changes in SCFA levels. However, due to the lack of a control group these findings would need to be verified in a rigorously controlled trial. Future work is also required to identify the biological mechanisms underlying the observed changes in microbiota activity and to explore if these processes can be harnessed to favorably impact host health.Clinical Trial Registration: www.clinicaltrials.gov, identifier NCT03615339; retrospectively registered on 03/08/2018.

Microbiota-Derived Short-Chain Fatty Acids Promote BMP Signaling by Inhibiting Histone Deacetylation and Contribute to Dentinogenic Differentiation in Murine Incisor Regeneration.

Microbiota and their metabolites short-chain fatty acids (SCFAs) have important roles in regulating tissue regeneration and mesenchymal stem cell (MSC) differentiation. In this study, we explored the potential effects of SCFAs on murine incisor regeneration and dental MSCs. We observed that SCFA deficiency induced by depletion of microbiota through antibiotic treatment led to lower renewal rate and delayed dentinogenesis in mice incisors. Supplementation with SCFAs in drinking water during antibiotic treatment can rescue the renewal rate and dentinogenesis effectively. In vitro, stimulation with SCFAs could promote differentiation of dental MSCs to odontoblasts. We further found that SCFAs could contribute to dentinogenic differentiation of dental MSCs by increasing bone morphogenetic protein (BMP) signal activation. SCFAs could inhibit deacetylation and increase BMP7 transcription of dental MSCs, which promoted BMP signaling. Our results suggested that SCFAs were required for incisor regeneration as well as differentiation of dental MSCs. Microbiota and their metabolites should be concerned as important factors in the tissue renewal and regeneration.

Gastrointestinal Disasters of Cetuximab in the Treatment of Metastatic Colorectal Cancer: Mechanism and its Effect on Prognosis

Colorectal cancer (CRC) is among the top three cancers worldwide in terms of incidence and associated mortality. Colorectal cancer (CRC) is responsible for more than 880,000 deaths annually. The number of of CRC cases worldwide continues to increase, posing a serious threat to human health. Surgery and chemotherapy are the first treatments for CRC patients. The majority of CRC patients are diagnosed at an advanced stage, as symptoms are usually not apparent and difficult to diagnose in the early stage. The prognosis of metastatic CRC (mCRC) has long been unsatisfactory. Targeted drugs therapy, which targeting at specific genes and proteins, is a new treatment approach to CRC. Cetuximab is one of the most widely studied targeted drugs. By competitively binding to the epithelial growth factor receptor (EGFR), cetuximab inhibits the EGF and binding of the EGF ligand to the EGFR, thereby inhibiting tumor cell growth, invasion, and metastasis and inducing tumor cell apoptosis. The curative effect of cetuximab as a treatment for many kinds of tumors, especially mCRC, has been confirmed. Cetuximab combined with chemotherapy or monotherapy is used as first-line treatment in patients with RAS(rat sarcoma,Ras) wild-type mCRC. However, adverse drug reactions (ADRs) associated with the clinical application of cetuximab are attracting increasing attention, with numerous studies reporting adverse effects of cetuximab on the gastrointestinal system, with these effects having adverse consequences for the prognosis of CRC. In this review, we focus mainly on gastrointestinal disasters on cetuximab treatment for mCRC from three areas: the intestinal mucosal barrier (IMB), gut microbiota (GM)-host immune balance, and bacterial metabolites short chain fatty acids (SCFAs), and the impact of these effects on the prognosis of mCRC. We also make suggestions aimed at aiding oncological understanding of cetuximab as a treatment for mCRC. Keywords: Bacterial metabolites, cetuximab, colorectal cancer, gut microbiota-host immune balance, gastrointestinal disasters

1578-P: Differences in Gut Microbiota between Diabetic and Nondiabetic Subjects

Objective: Since gut microbiota activity results in the production of specific microbial-derived metabolites (short-chain fatty acids) and structural components (LPS and peptidoglycans), changes in such microbiota composition appears to be involved in pathophysiology of common chronic disorders such as diabetes. Indeed, differences in gut microbiota between diabetic and nondiabetic subjects have been reported frequently in many ethnic groups, but not frequently in Japanese populations. Research Design and Methods: Among participants of the population-based Iwaki study of Japanese held in 2016, those with information of gut microbiota evaluated using 16S rRNA sequencing were included in the study (gender (M/F): 446/672; age: 54.8±15.6). Diabetic (n=122): either on treatment for diabetes or HbA1c levels ≥6.5% or FBG ≥126 mg/dl; Nondiabetic (n=996): others. Results: When examined the differences in gut microbiota in taxonomy category genus, proportions of several genuses were different between diabetic and nondiabetic subjects. Especially, proportions of the genus Streptococcus (4.79±9.53% vs. 2.12±3.74%, p=0.011) and Lactobacillus (3.11±8.10% vs. 0.344±1.95%, p &amp;lt;0.01), which are known to produce lactic acid, were higher, and genus Blautia (5.52±4.26% vs. 7.31±4.37%, p &amp;lt;0.01) and Bacteroides (8.14±9.38% vs. 10.8±7.84%, p &amp;lt;0.01), which are known to produce short chain fatty acids, were lower in diabetics subjects than those in nondiabetic subjects. Conclusions: Differences in gut microbiota proportion were also found between diabetic and nondiabetic subjects in a Japanese population. Since lactic acid is known to have an effect of suppressing pathogenic bacteria, the increase in lactic acid producing bacteria may have effects against infection. Further, since short chain fatty acids act as signal transduction molecules that affect energy metabolism, the decrease in short-chain fatty acid producing bacteria may be involved in the development of diabetes. Disclosure M. Murabayashi: None. M. Daimon: None. H. Murakami: None. Y. Matsuhashi: None. A. Kamba: None. S. Mizushiri: None.

Intergenerational transfer of Dechlorane Plus and the associated long-term effects on the structure and function of gut microbiota in offspring

The gut microbiota has been shown to be highly involved in many vital physiological processes that play key roles in human health. The intergenerational transfer of Dechlorane Plus (DP) and the complex interaction between DP and microbiota has been poorly studied. Additionally, the structural and functional effects of DP on the gut microbiota have not been studied. This study aimed to investigate the DP transfer in Sprague-Dawley rats during pregnancy and the effects of DP exposure on gut microbiota, as detected by 16S rRNA gene sequencing. The results showed that excretion in feces is a very important elimination pathway of orally dosed DP. The main intergenerational transfer pathway of DP might be via lactation rather than transplacental transport. The 16S rRNA sequencing revealed that DP exposure could decrease the richness and diversity of gut microbiota, especially at the genus level. Furthermore, in DP exposure groups, the gut microbiota production of metabolites of short-chain fatty acids was dramatically increased. The results demonstrated that DP exposure not only altered the gut microbiota structures, but also immensely influenced metabolic functions, causing long-term impact to offspring. This data indicates that more attention should be paid to the long-term health effects related to DP exposure.

Modulation of Gut Microbial Community and Metabolism by Dietary Glycyl-Glutamine Supplementation May Favor Weaning Transition in Piglets.

Gut microbiota plays a crucial role in diet nutrient metabolism and maintaining host health. The synthetic dipeptides glycyl-glutamine (Gly-Gln) used as diet supplementation to improve the weaning transition of newborns could be metabolized by certain bacteria in vitro. However, the effect of diet Gly-Gln supplementation on gut microbiota in vivo remains largely unknown. 240 piglets at the age of 28 days (day 28) were randomly assigned to two groups that received a basal diet (Ctrl group) or a basal diet supplemented with 0.25% Gly-Gln (Gly-Gln group) for 3 weeks. Five piglets from each group were euthanized for sampling after overnight fasting on day 38 and day 49, respectively. We determined their structure shifts of the gut microbiota using 16S rDNA-based high-throughput sequencing analysis. Microbial metabolites short-chain fatty acids (SCFAs) in the ileum and the colon were determined with high-performance gas chromatography. The concentrations of endocrine peptides including epidermal growth factor, glucagon-like peptide-1, and glucagon-like peptide-2 in ileal mucosa, as well as the serum concentration of interleukin 1 beta, interleukin 6, interleukin 10, and tumor necrosis factor alpha were determined using Enzyme-Linked Immunosorbent Assay. In addition, we also checked the diarrhea ratio, growth performance, and intestinal morphology to assess the favorable effect of dietary Gly-Gln supplementation during the weaning transition. Dietary Gly-Gln supplementation beneficially altered the gut microbiota by increasing bacterial loading, elevating alpha diversity, and increasing the relative abundance of anaerobes and fiber-degrading bacteria (Phylum Fibrobacteres). Accordingly, the microbial metabolites SCFAs in both colon and ileum, as well as the downstream endocrine peptides in the ileum increased. Meanwhile, dietary Gly-Gln’s favorable weaning transition was reflected in the increase of growth performance indices and the reduced inflammatory response in a time dependent manner. There were significant correlations among the bacteria which responded to dietary Gly-Gln supplementation and these checked indices. Taken together, dietary Gly-Gln supplementation selectively modulated the gut microbiota, which may favor piglets’ weaning-transition. These findings suggest that gut microbiota targeted approaches can be potentially used to improve weaning transition of piglets by dietary functional amino acid.

Amyloid-Polyphenol Hybrid Nanofilaments Mitigate Colitis and Regulate Gut Microbial Dysbiosis.

It is a desirable and powerful strategy to precisely fabricate functional soft matter through self-assembly of molecular building blocks across a range of length scales. Proteins, nucleic acids, and polyphenols are the self-assemblers ubiquitous in nature. Assembly of proteins into flexible biocolloids, amyloid fibrils with high aspect ratio, has emerged as an unchallenged templating strategy for high-end technological materials and bio-nanotechnologies. We demonstrate the ability of these fibrils to support the deposition and self-assembly of polyphenols into hybrid nanofilaments and functional macroscopic hydrogels made thereof. The length scale of the substance that amyloid fibrils can attach with acting as the building templates was extended from nanometer down to sub-nanometer. Significantly increased loading capacities of polyphenols (up to 4.0 wt %) compared to that of other delivery systems and improved stability were realized. After oral administration, the hydrogels could transport from the stomach to the small intestine and finally to the gut (cecum, colon, rectum), with a long retention time in the colon. Oral administration of the hydrogels significantly ameliorated colitis in a mouse model, promoted intestinal barrier function, suppressed the pro-inflammatory mRNA expression, and very significantly (P < 0.01) regulated gut microbial dysbiosis. Specifically, it reduced the abundance of normally enriched operational taxonomic units related to colitis, especially targeting facultative anaerobes of the phylum Proteobacteria, such as Aestuariispira and Escherichia. The short-chain fatty acid metabolites were enriched. Combined with their nontoxic nature observed in this long-term study in mice, the obtained amyloid-polyphenol gels have high application potentials for gastrointestinal diseases by "drugging the microbiome".

Seabuckthorn (Hippophaë rhamnoides) Freeze-Dried Powder Protects against High-Fat Diet-Induced Obesity, Lipid Metabolism Disorders by Modulating the Gut Microbiota of Mice.

This study aimed to investigate the beneficial effects of seabuckthorn freeze-dried powder on high-fat diet-induced obesity and related lipid metabolism disorders, and further explored if this improvement is associated with gut microbiota. Results showed that seabuckthorn freeze-dried powder administration decreased body weight, Lee’s index, adipose tissue weight, liver weight, and serum lipid levels. Moreover, treatment with seabuckthorn freeze-dried powder effectively reduced fat accumulation by modulating the relative expression of genes involved in lipid metabolism through down-regulation of encoding lipogenic and store genes, including SREBP-1c, PPAR-γ, ACC, and SCD1, and up-regulation of regulating genes of fatty acid oxidation, including HSL, CPT-1, and ACOX. Especially, seabuckthorn freeze-dried powder regulated the composition of gut microbiota, such as increasing the ratio of Firmicutes/Bacteroidetes, decreasing relative abundance of harmful bacteria (Desulfovibrio), and increasing relative abundance of beneficial bacteria (Akkermansia and Bacteroides). The changes of beneficial bacteria had a positive correlation with genes encoding lipolysis and a negative correlation with genes encoding lipid lipogenesis and store. The harmful bacteria were just the opposite. Besides, changes in gut microbiota had an obvious effect in the secretion of main metabolites—short-chain fatty acids (SCFAs), especially propionic acid. Thus, our results indicated that the seabuckthorn freeze-dried powder could ameliorate high-fat diet-induced obesity and obesity-associated lipid metabolism disorders by changing the composition and structure of gut microbiota.