Fatty acids from diet and microbiota regulate energy metabolism

Identification of an epilepsy-linked gut microbiota signature in a pediatric rat model of acquired epilepsy

A dysfunctional gut microbiota-brain axis is emerging as a potential pathogenic mechanism in epilepsy, particularly in pediatric forms of epilepsy. To add new insights into gut-related changes in acquired epilepsy that develops early in life, we used a multi-omics approach in a rat model with a 56% incidence of epilepsy. The presence of spontaneous seizures was assessed in adult rats (n = 46) 5 months after status epilepticus induced by intra-amygdala kainate at postnatal day 13, by 2 weeks (24/7) ECoG monitoring. Twenty-six rats developed epilepsy (Epi) while the remaining 20 rats (No-Epi) did not show spontaneous seizures. At the end of ECoG monitoring, all rats and their sham controls (n = 20) were sacrificed for quantitative histopathological and immunohistochemical analyses of the gut structure, glia and macrophages, as well as RTqPCR analysis of inflammation/oxidative stress markers. By comparing Epi, No-Epi rats, and sham controls, we found structural, cellular, and molecular alterations reflecting a dysfunctional gut, which were specifically associated with epilepsy. In particular, the villus height-to-crypt depth ratio and number of Goblet cells were reduced in the duodenum of Epi rats vs both No-Epi rats and sham controls (p < 0.01). Villus height and crypt depth in the duodenum and jejunum (p < 0.01) were increased in No-Epi vs both Epi and sham controls. We also detected enhanced Iba1-positive macrophages, together with increased IL1b and NFE2L2 transcripts and TNF protein, in the small intestine of Epi vs both No-Epi and sham control rats (p < 0.01), denoting the presence of inflammation and oxidative stress. Astroglial GFAP-immunostaining was similar in all experimental groups. Metagenomic analysis in the feces collected 5 months after status epilepticus showed that the ratio of two dominant phyla (Bacteroidota-to-Firmicutes) was similarly increased in Epi and No-Epi rats vs sham control rats. Notably, the relative abundance of families, genera, and species associated with SCFA production differed in Epi vs No-Epi rats, describing a bacterial imprint associated with epilepsy. Furthermore, Epi rats showed a blood metabolic signature characterized by changes in lipid metabolism compared to both No-Epi and sham control rats. Our study provides new evidence of long-term gut alterations, along with microbiota-related metabolic changes, occurring specifically in rats that develop epilepsy after brain injury early in life.

Metabolomic signatures of intestinal colonization resistance against Campylobacter jejuni in mice

Introduction

Campylobacter jejuni stands out as one of the leading causes of bacterial enteritis. In contrast to humans, specific pathogen-free (SPF) laboratory mice display strict intestinal colonization resistance (CR) against C. jejuni, orchestrated by the specific murine intestinal microbiota, as shown by fecal microbiota transplantation (FMT) earlier.

Methods

Murine infection models, comprising SPF, SAB, hma, and mma mice were employed. FMT and microbiota depletion were confirmed by culture and culture-independent analyses. Targeted metabolome analyses of fecal samples provided insights into the associated metabolomic signatures.

Results

In comparison to hma mice, the murine intestinal microbiota of mma and SPF mice (with CR against C. jejuni) contained significantly elevated numbers of lactobacilli, and Mouse Intestinal Bacteroides, whereas numbers of enterobacteria, enterococci, and Clostridium coccoides group were reduced. Targeted metabolome analysis revealed that fecal samples from mice with CR contained increased levels of secondary bile acids and fatty acids with known antimicrobial activities, but reduced concentrations of amino acids essential for C. jejuni growth as compared to control animals without CR.

Discussion

The findings highlight the role of microbiota-mediated nutrient competition and antibacterial activities of intestinal metabolites in driving murine CR against C. jejuni. The study underscores the complex dynamics of host-microbiota-pathogen interactions and sets the stage for further investigations into the mechanisms driving CR against enteric infections.

Exploring body weight-influencing gut microbiota by elucidating the association with diet and host gene expression

We aimed to identify gut microbiota that influences body weight by elucidating the association with diets and host genes. Germ-free (GF) mice with and without fecal microbiota transplant (FMT) were fed a normal, high-carbohydrate, or high-fat diet. FMT mice exhibited greater total body weight; adipose tissue and liver weights; blood glucose, insulin, and total cholesterol levels; and oil droplet size than the GF mice, regardless of diet. However, the extent of weight gain and metabolic parameter levels associated with gut microbiota depended on the nutrients ingested. For example, a disaccharide- or polysaccharide-rich diet caused more weight gain than a monosaccharide-rich diet. An unsaturated fatty acid-rich diet had a greater microbial insulin-increasing effect than a saturated fatty acid-rich diet. Perhaps the difference in microbial metabolites produced from substances taken up by the host created metabolic differences. Therefore, we analyzed such dietary influences on gut microbiota, differentially expressed genes between GF and FMT mice, and metabolic factors, including body weight. The results revealed a correlation between increased weight gain, a fat-rich diet, increased Ruminococcaceae abundance, and decreased claudin 22 gene expression. These findings suggest that weight regulation might be possible through the manipulation of the gut microbiota metabolism using the host's diet.

Different Effects of Lard and Vegetable Blend Oil on Intestinal Microorganisms, Enzyme Activity and Blood Routine in Mice

The intake of moderate oils and fats is necessary to maintain the body's energy balance, and the fatty acid composition of different oils and fats varies in their nutrition and function. The study aimed to investigate the effects of lard and vegetable blend oil on gut microbiota, intestinal enzyme activities, and blood routine. Kunming mice were assigned to the three groups: (1) Control group (CK) was gavage administration with distilled water, (2) Plant oil group (ZWY) was gavage administration with edible vegetable blend oil, (3) Lard group (DWY) was gavage administration with lard. After 42 days, microbiological, digestive enzymes, and blood routine were performed. Compared with the CK group, Escherichia coli, Lactobacilli, and Bifidobacteria were significantly decreased (p < 0.05), the activities of protease, cellulase, amylase, and xylanase were markedly reduced (p < 0.05), the hemoglobin was significantly increased (p < 0.05) in the ZWY group and DWY groups, and the hematocrit was increased in the ZWY group (p < 0.05), while other routine blood indices were increased (p > 0.05). Compared to the ZWY group, the activity of cellulase and amylase were significantly increased (p < 0.05), the intestinal microorganism and the routine blood indexes had no significant difference in the DWY group. Lard and vegetable blend oil diet affected the composition of the intestinal microorganisms, and the functions of digestive enzymes. Meanwhile, the levels of digestive enzymes may be correlated with the intestinal microbiota.

Plasma Lipolysis and Changes in Plasma and Cerebrospinal Fluid Signaling Lipids Reveal Abnormal Lipid Metabolism in Chronic Migraine

Background

Lipids are a primary storage form of energy and the source of inflammatory and pain signaling molecules, yet knowledge of their importance in chronic migraine (CM) pathology is incomplete. We aim to determine if plasma and cerebrospinal fluid (CSF) lipid metabolism are associated with CM pathology.

Methods

We obtained plasma and CSF from healthy controls (CT, n = 10) or CM subjects (n = 15) diagnosed using the International Headache Society criteria. We measured unesterified fatty acid (UFA) and esterified fatty acids (EFAs) using gas chromatography-mass spectrometry. Glycerophospholipids (GP) and sphingolipid (SP) levels were determined using LC-MS/MS, and phospholipase A₂ (PLA₂) activity was determined using fluorescent substrates.

Results

Unesterified fatty acid levels were significantly higher in CM plasma but not in CSF. Unesterified levels of five saturated fatty acids (SAFAs), eight monounsaturated fatty acids (MUFAs), five ω-3 polyunsaturated fatty acids (PUFAs), and five ω-6 PUFAs are higher in CM plasma. Esterified levels of three SAFAs, eight MUFAs, five ω-3 PUFAs, and three ω-6 PUFAs, are higher in CM plasma. The ratios C20:4n-6/homo-γ-C20:3n-6 representative of delta-5-desaturases (D5D) and the elongase ratio are lower in esterified and unesterified CM plasma, respectively. In the CSF, the esterified D5D index is lower in CM. While PLA₂ activity was similar, the plasma UFA to EFA ratio is higher in CM. Of all plasma GP/SPs detected, only ceramide levels are lower (p = 0.0003) in CM (0.26 ± 0.07%) compared to CT (0.48 ± 0.06%). The GP/SP proportion of platelet-activating factor (PAF) is significantly lower in CM CSF.

Conclusions

Plasma and CSF lipid changes are consistent with abnormal lipid metabolism in CM. Since plasma UFAs correspond to diet or adipose tissue levels, higher plasma fatty acids and UFA/EFA ratios suggest enhanced adipose lipolysis in CM. Differences in plasma and CSF desaturases and elongases suggest altered lipid metabolism in CM. A lower plasma ceramide level suggests reduced de novo synthesis or reduced sphingomyelin hydrolysis. Changes in CSF PAF suggest differences in brain lipid signaling pathways in CM. Together, this pilot study shows lipid metabolic abnormality in CM corresponding to altered energy homeostasis. We propose that controlling plasma lipolysis, desaturases, elongases, and lipid signaling pathways may relieve CM symptoms.

Adherence to Mediterranean diet impacts gastrointestinal microbial diversity throughout pregnancy

Background

Consumption of a diet with high adherence to a Mediterranean diet pattern (MDP) has been associated with a favorable gastrointestinal tract (GIT) microbiome. A healthy GIT microbiome in pregnancy, as defined by increased alpha diversity, is associated with lower chance of adverse perinatal outcomes. This study aimed to evaluate the impact of adherence to an MDP on GIT microbial diversity longitudinally throughout pregnancy.

Methods

Adherence to MDP was scored by the Alternate Mediterranean (aMED) Diet Quality Score, after being applied to a validated Food Frequency Questionnaire. Association of aMED Scores with GIT alpha diversity profiles were compared linearly and across time using a linear mixed model, including covariates of age, body mass index (BMI), ethnicity, and parity.

Results

Forty-one participants of Filipino, Japanese, Native Hawaiian, and Non-Hispanic White descent provided dietary information and microbiome samples during each trimester of pregnancy. Alpha diversity profiles changed over gestation, with decreased microbial diversity in the third trimester. aMED scores positively correlated with Chao1 Index and Observed Species Number (r = 0.244, p = 0.017, and r = 0.233, p = 0.023, respectively). The strongest association was detected in the third trimester (Chao 1: r = 0.43, p = 0.020, Observed Species Number: r = 0.41, p = 0.026). Participants with higher aMED scores had higher relative abundance of Acidaminoacaeae at the family level (p = 0.0169), as well as higher abundance of several species known to increase production of short chain fatty acids within the GIT.

Conclusions

Adherence to MDP pattern is associated with increased maternal GIT microbial diversity, and promotes the abundance of bacteria that produce short chain fatty acids. Increased consumption of fruits, vegetables and legumes with low red meat consumption were key components driving this association. The effect of nutrition however, was less of an effect than pregnancy itself. Further studies are needed to determine if adherence to a Mediterranean diet translates not only into microbial health, but also into reduced risk of adverse pregnancy outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-04033-8.

Long-chain saturated fatty acids in breast milk are associated with the pathogenesis of atopic dermatitis via induction of inflammatory ILC3s

Breastfeeding influences the immune system development in infants and may even affect various immunological responses later in life. Breast milk provides a rich source of early nutrition for infant growth and development. However, the presence of certain compounds in breast milk, related to an unhealthy lifestyle or the diet of lactating mothers, may negatively impact infants. Based on a cohort study of atopic dermatitis (AD), we find the presence of damage-associated molecular patterns (DAMPs) activity in the mother's milk. By non-targeted metabolomic analysis, we identify the long-chain saturated fatty acids (LCSFA) as a biomarker DAMPs (+) breast milk samples. Similarly, a mouse model in which breastfed offspring are fed milk high in LCSFA show AD onset later in life. We prove that LCSFA are a type of damage-associated molecular patterns, which initiate a series of inflammatory events in the gut involving type 3 innate lymphoid cells (ILC3s). A remarkable increase in inflammatory ILC3s is observed in the gut, and the migration of these ILC3s to the skin may be potential triggers of AD. Gene expression analysis of ILC3s isolated from the gut reveal upregulation of genes that increase ILC3s and chemokines/chemokine receptors, which may play a role in ILC migration to the skin. Even in the absence of adaptive immunity, Rag1 knockout mice fed a high-LCSFA milk diet develop eczema, accompanied by increased gut ILC3s. We also present that gut microbiota of AD-prone PA milk-fed mice is different from non-AD OA/ND milk-fed mice. Here, we propose that early exposure to LCSFAs in infants may affect the balance of intestinal innate immunity, inducing a highly inflammatory environment with the proliferation of ILC3s and production of interleukin-17 and interleukin-22, these factors may be potential triggers or worsening factors of AD.

Dietary intake and plasma phospholipid concentrations of saturated, monounsaturated and trans fatty acids and colorectal cancer risk in the European Prospective Investigation into Cancer and Nutrition cohort

Epidemiologic studies examining the association between specific fatty acids and colorectal cancer (CRC) risk are inconclusive. We investigated the association between dietary estimates and plasma levels of individual and total saturated (SFA), monounsaturated (MUFA), industrial-processed trans (iTFA), and ruminant-sourced trans (rTFA) fatty acids, and CRC risk in the European Prospective Investigation into Cancer and Nutrition (EPIC). Baseline fatty acid intakes were estimated in 450 112 participants (6162 developed CRC, median follow-up = 15 years). In a nested case-control study, plasma phospholipid fatty acids were determined by gas chromatography in 433 colon cancer cases and 433 matched controls. Multivariable-adjusted hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were computed using Cox and conditional logistic regression, respectively. Dietary total SFA (highest vs lowest quintile, HRQ5vsQ1  = 0.80; 95%CI:0.69-0.92), myristic acid (HRQ5vsQ1  = 0.83, 95%CI:0.74-0.93) and palmitic acid (HRQ5vsQ1  = 0.81, 95%CI:0.70-0.93) were inversely associated with CRC risk. Plasma myristic acid was also inversely associated with colon cancer risk (highest vs lowest quartile, ORQ4vsQ1  = 0.51; 95%CI:0.32-0.83), whereas a borderline positive association was found for plasma stearic acid (ORQ4vsQ1  = 1.63; 95%CI:1.00-2.64). Dietary total MUFA was inversely associated with colon cancer (per 1-SD increment, HR1-SD  = 0.92, 95%CI: 0.85-0.98), but not rectal cancer (HR1-SD  = 1.04, 95%CI:0.95-1.15, Pheterogeneity  = 0.027). Dietary iTFA, and particularly elaidic acid, was positively associated with rectal cancer (HR1-SD  = 1.07, 95%CI:1.02-1.13). Our results suggest that total and individual saturated fatty acids and fatty acids of industrial origin may be relevant to the aetiology of CRC. Both dietary and plasma myristic acid levels were inversely associated with colon cancer risk, which warrants further investigation.

Impact of Maternal Nutritional Supplementation during Pregnancy and Lactation on the Infant Gut or Breastmilk Microbiota: A Systematic Review

Recent evidence indicates that maternal dietary intake, including dietary supplements, during pregnancy and lactation may alter the infant gut or breastmilk microbiota, with implications for health outcomes in both the mother and infant. To review the effects of maternal nutritional supplementation during pregnancy and lactation on the infant gut or breastmilk microbiota a systematic literature search was conducted. A total of 967 studies published until February 2020 were found, 31 were eligible and 29 randomized control trials were included in the qualitative synthesis. There were 23 studies that investigated the effects of probiotic supplementation, with the remaining studies investigating vitamin D, prebiotics or lipid-based nutrient supplements (LNS). The effects of maternal nutritional supplementation on the infant gut microbiota or breastmilk microbiota were examined in 21 and 12 studies, respectively. Maternal probiotic supplementation during pregnancy and lactation generally resulted in the probiotic colonization of the infant gut microbiota, and although most studies also reported alterations in the infant gut bacterial loads, there was limited evidence of effects on bacterial diversity. The data available show that maternal probiotic supplementation during pregnancy or lactation results in probiotic colonization of the breastmilk microbiota. There were no observed effects between probiotic supplementation and breastmilk bacterial counts of healthy women, however, administration of Lactobacillus probiotic to nursing women affected by mastitis was associated with significant reductions in breastmilk Staphylococcal loads. Maternal LNS supplementation during pregnancy and lactation increased bacterial diversity in the infant gut, whilst vitamin D and prebiotic supplementation did not alter either infant gut bacterial diversity or counts. Heterogeneity in study design precludes any firm conclusions on the effects of maternal nutritional supplementation during pregnancy and lactation on the infant gut or breastmilk microbiota, warranting further research.

Soluble Fiber Inulin Consumption Limits Alterations of the Gut Microbiota and Hepatic Fatty Acid Metabolism Caused by High-Fat Diet

Diet shapes the gut microbiota which impacts hepatic lipid metabolism. Modifications in liver fat content are associated with metabolic disorders. We investigated the extent of dietary fat and fiber-induced alterations in the composition of gut microbiota and hepatic fatty acids (FAs). Mice were fed a purified low-fat diet (LFD) or high-fat diet (HFD) containing non-soluble fiber cellulose or soluble fiber inulin. HFD induced hepatic decreases in the amounts of C14:0, C16:1n-7, C18:1n-7 and increases in the amounts of C17:0, C20:0, C16:1n-9, C22:5n-3, C20:2n-6, C20:3n-6, and C22:4n-6. When incorporated in a LFD, inulin poorly affected the profile of FAs. However, when incorporated in a HFD, it (i) specifically led to an increase in the amounts of hepatic C18:0, C22:0, total polyunsaturated FAs (PUFAs), total n-6 PUFAs, C18:3n-3, and C18:2n-6, (ii) exacerbated the HFD-induced increase in the amount of C17:0, and (iii) prevented the HFD-induced increases in C16:1n-9 and C20:3n-6. Importantly, the expression/activity of some elongases and desaturases, as well as the gut microbiota composition, were impacted by the dietary fat and fiber content. To conclude, inulin modulated gut microbiota and hepatic fatty acid composition, and further investigations will determine whether a causal relationship exists between these two parameters.

Different effects of high-fat diets rich in different oils on lipids metabolism, oxidative stress and gut microbiota

The study aimed to investigate the different effects of high-fat (HF) diets rich in different oils on lipid metabolism, oxidative stress, and gut mirobiota. C57BL/6 mice were divided into 4 groups: (1) control group (CG) was fed with normal diet, (2) olive oil (OO) group was fed with high-fat diet containing OO, (3) lard oil (LO) group was fed with high-fat diet containing LO, (4) soybean oil (SO) group was fed with high-fat diet containing SO. After 12 weeks, serum lipids, and oxidative stress indices were analyzed. Gut microbiota analysis was carried out based on the sequencing results of 16S rRNA. High fat diet can increase serum and liver lipids and upregulate sterol regulatory element-binding protein-1c related genes expression. Serum and liver malondialdehyde (MDA) levels in LO group were significantly higher than those in CG and OO groups. In CG, the family Muribaculaceae, Lactobacillaceae, Lachnospiraceae and Desulfovibrionaceae had the large effect sizes. HF diets resulted in the increase of Actinobacteria and Enterococcaceae abundance, and the decrease of Bacteroidetes, Proteobacteria Lactobacillales and microbiota diversity. The abundance of Actinobacteria and Lactobacillales is the link to the serum TC and MDA levels. HF diets have the harmful influence on the serum lipids, oxidative stress and endothelial function. They can also cause gut microbiota dysbiosis.

Inferring Relationship of Blood Metabolic Changes and Average Daily Gain With Feed Conversion Efficiency in Murrah Heifers: Machine Learning Approach

Machine learning algorithms were employed for predicting the feed conversion efficiency (FCE), using the blood parameters and average daily gain (ADG) as predictor variables in buffalo heifers. It was observed that isotonic regression outperformed other machine learning algorithms used in study. Further, we also achieved the best performance evaluation metrics model with additive regression as the meta learner and isotonic regression as the base learner on 10-fold cross-validation and leaving-one-out cross-validation tests. Further, we created three separate partial least square regression (PLSR) models using all 14 parameters of blood and ADG as independent (explanatory) variables and FCE as the dependent variable, to understand the interactions of blood parameters, ADG with FCE each by inclusion of all FCE values (i), only higher FCE values (negative RFI) (ii), and inclusion of only lower FCE (positive RFI) values (iii). The PLSR model including only the higher FCE values was concluded the best, based on performance evaluation metrics as compared to PLSR models developed by inclusion of the lower FCE values and all types of FCE values. IGF1 and its interactions with the other blood parameters were found highly influential for higher FCE measures. The strength of the estimated interaction effects of the blood parameter in relation to FCE may facilitate understanding of intricate dynamics of blood parameters for growth.

Knockout of the non-essential gene SUGCT creates diet-linked, age-related microbiome disbalance with a diabetes-like metabolic syndrome phenotype

SUGCT (C7orf10) is a mitochondrial enzyme that synthesizes glutaryl-CoA from glutarate in tryptophan and lysine catabolism, but it has not been studied in vivo. Although mutations in Sugct lead to Glutaric Aciduria Type 3 disease in humans, patients remain largely asymptomatic despite high levels of glutarate in the urine. To study the disease mechanism, we generated SugctKO mice and uncovered imbalanced lipid and acylcarnitine metabolism in kidney in addition to changes in the gut microbiome. After SugctKO mice were treated with antibiotics, metabolites were comparable to WT, indicating that the microbiome affects metabolism in SugctKO mice. SUGCT loss of function contributes to gut microbiota dysbiosis, leading to age-dependent pathological changes in kidney, liver, and adipose tissue. This is associated with an obesity-related phenotype that is accompanied by lipid accumulation in kidney and liver, as well as "crown-like" structures in adipocytes. Furthermore, we show that the SugctKO kidney pathology is accelerated and exacerbated by a high-lysine diet. Our study highlights the importance of non-essential genes with no readily detectable early phenotype, but with substantial contributions to the development of age-related pathologies, which result from an interplay between genetic background, microbiome, and diet in the health of mammals.

Role of diet on intestinal metabolites and appetite control factors in SD rats

The present study aimed to investigate changes in the levels of metabolites and appetite control factors caused by different dietary interventions in Sprague Dawley (SD) rats. A total of 35 male SD rats were weaned and immediately randomly assigned to five groups. The control group was given ad libitum access to a normal chow diet, and the other groups received a high-fat diet (FAT group), high-sugar diet, high-fibre or high-protein diet (PRO group) for 4 weeks. The high-fat diet contributed to weight gain and adipose tissue formation, and affected lipid indexed. The FAT group had a higher body weight, Lee's index, adipose mass and glucose tolerance than all of the other groups. The opposite effect was observed in the PRO group. High-performance liquid chromatography revealed that short-chain fatty acid and amino acid formation were affected by the various diets. In addition, differences in the mRNA expression levels of leptin, ghrelin and associated receptors were determined in the gastrointestinal, adipose and hypothalamus tissues. The present study provides further evidence of the role of diet in obesity development and prevention. It also highlights the role of intestinal metabolites and appetite control factor expression in the pathogenesis of obesity in SD rats.

Gastrointestinal Disorders and Metabolic Syndrome: Dysbiosis as a Key Link and Common Bioactive Dietary Components Useful for their Treatment

Gastrointestinal (GI) diseases, which include gastrointestinal reflux disease, gastric ulceration, inflammatory bowel disease, and other functional GI disorders, have become prevalent in a large part of the world population. Metabolic syndrome (MS) is cluster of disorders including obesity, hyperglycemia, hyperlipidemia, and hypertension, and is associated with high rate of morbidity and mortality. Gut dysbiosis is one of the contributing factors to the pathogenesis of both GI disorder and MS, and restoration of normal flora can provide a potential protective approach in both these conditions. Bioactive dietary components are known to play a significant role in the maintenance of health and wellness, as they have the potential to modify risk factors for a large number of serious disorders. Different classes of functional dietary components, such as dietary fibers, probiotics, prebiotics, polyunsaturated fatty acids, polyphenols, and spices, possess positive impacts on human health and can be useful as alternative treatments for GI disorders and metabolic dysregulation, as they can modify the risk factors associated with these pathologies. Their regular intake in sufficient amounts also aids in the restoration of normal intestinal flora, resulting in positive regulation of insulin signaling, metabolic pathways and immune responses, and reduction of low-grade chronic inflammation. This review is designed to focus on the health benefits of bioactive dietary components, with the aim of preventing the development or halting the progression of GI disorders and MS through an improvement of the most important risk factors including gut dysbiosis.

Gut microbiota-derived metabolites in obesity: a systematic review

Recent evidence suggests that gut microbiota-derived metabolites affect many biological processes of the host, including appetite control and weight management. Dysbiosis of the gut microbiome in obesity influences the metabolism and excretion of gut microbiota byproducts and consequently affects the physiology of the host. Since identification of the gut microbiota-host co-metabolites is essential for clarifying the interactions between the intestinal flora and the host, we conducted this systematic review to summarize all human studies that characterized the gut microbiota-related metabolites in overweight and obese individuals. A comprehensive search of the PubMed, Web of Science, and Scopus databases yielded 2,137 articles documented up to July 2018. After screening abstracts and full texts, 12 articles that used different biosamples and methodologies of metabolic profiling and fecal microbiota analysis were included. Amino acids and byproducts of amino acids, lipids and lipid-like metabolites, bile acids derivatives, and other metabolites derived from degradation of carnitine, choline, polyphenols, and purines are among the gut microbiota-derived metabolites which showed alterations in obesity. These metabolites play an important role in metabolic complications of obesity, including insulin resistance, hyperglycemia, and dyslipidemia. The results of this study could be useful in development of therapeutic strategies with the aim of modulating gut microbiota and consequently the metabolic profile in obesity.

Tomato seed oil attenuates hyperlipidemia and modulates gut microbiota in C57BL/6J mice

TSO can significantly improve fatty acid metabolism and cholesterol metabolism, thereby inhibiting obesity and hypercholesterolemia. TSO can favorably modulate the gut microbiota.

The Intervention Effect of Traditional Chinese Medicine on the Intestinal Flora and Its Metabolites in Glycolipid Metabolic Disorders

Metabolic syndrome (MS), which includes metabolic disorders such as protein disorder, glucose disorder, lipid disorder, and carbohydrate disorder, has been growing rapidly around the world. Glycolipid disorders are a main type of metabolic syndrome and are characterized by abdominal obesity and abnormal metabolic disorders of lipid, glucose, and carbohydrate utilization, which can cause cardiovascular and cerebrovascular diseases. Glycolipid disorders are closely related to intestinal flora and its metabolites. However, studies about the biological mechanisms of the intestinal flora and its metabolites with glycolipid disorders have not been clear. When glycolipid disorders are treated with drugs, a challenging problem is side effects. Traditional Chinese medicine (TCM) and dietary supplements have fewer side effects to treat it. Numerous basic and clinical studies have confirmed that TCM decoctions, Chinese medicine monomers, or compounds can treat glycolipid disorders and reduce the incidence of cardiovascular disease. In this study, we reviewed the relationship between the intestinal flora and its metabolites in glycolipid metabolic disorders and the effect of TCM in treating glycolipid metabolic disorders through the intestinal flora and its metabolites. This review provides new perspectives and strategies for future glycolipid disorders research and treatment.

Dietary fat, the gut microbiota, and metabolic health - A systematic review conducted within the MyNewGut project

BACKGROUND AND AIMS

Studies indicate that dietary fat quantity and quality influence the gut microbiota composition which may as a consequence impact metabolic health. This systematic review aims to summarize the results of available studies in humans on dietary fat intake (quantity and quality), the intestinal microbiota composition and related cardiometabolic health outcomes.

METHODS

We performed a systematic review (CRD42018088685) following PRISMA guidelines and searched for literature in Medline, EMBASE, and Cochrane databases.

RESULTS

From 796 records, 765 records were excluded based on title or abstract. After screening of 31 full-text articles six randomized controlled trials (RCT) and nine cross-sectional observational studies were included. Our results of interventional trials do not suggest strong effects of different amounts and types of dietary fat on the intestinal microbiota composition or on metabolic health outcomes while observational studies indicate associations with the microbiota and health outcomes. High intake of fat and saturated fatty acids (SFA) may negatively affect microbiota richness and diversity and diets high in monounsaturated fatty acids (MUFA) may decrease total bacterial numbers whereas dietary polyunsaturated fatty acids (PUFA) had no effect on richness and diversity.

CONCLUSIONS

High fat and high SFA diets can exert unfavorable effects on the gut microbiota and are associated with an unhealthy metabolic state. Also high MUFA diets may negatively affect gut microbiota whereas PUFA do not seem to negatively affect the gut microbiota or metabolic health outcomes. However, data are not consistent and most RCT and observational studies showed risks of bias.

Prenatal androgen exposure causes hypertension and gut microbiota dysbiosis

BACKGROUND

Conditions of excess androgen in women, such as polycystic ovary syndrome (PCOS), often exhibit intergenerational transmission. One way in which the risk for PCOS may be increased in daughters of affected women is through exposure to elevated androgens in utero. Hyperandrogenemic conditions have serious health consequences, including increased risk for hypertension and cardiovascular disease. Recently, gut dysbiosis has been found to induce hypertension in rats, such that blood pressure can be normalized through fecal microbial transplant. Therefore, we hypothesized that the hypertension seen in PCOS has early origins in gut dysbiosis caused by in utero exposure to excess androgen. We investigated this hypothesis with a model of prenatal androgen (PNA) exposure and maternal hyperandrogenemia by single-injection of testosterone cypionate or sesame oil vehicle (VEH) to pregnant dams in late gestation. We then completed a gut microbiota and cardiometabolic profile of the adult female offspring.

RESULTS

The metabolic assessment revealed that adult PNA rats had increased body weight and increased mRNA expression of adipokines: adipocyte binding protein 2, adiponectin, and leptin in inguinal white adipose tissue. Radiotelemetry analysis revealed hypertension with decreased heart rate in PNA animals. The fecal microbiota profile of PNA animals contained higher relative abundance of bacteria associated with steroid hormone synthesis, Nocardiaceae and Clostridiaceae, and lower abundance of Akkermansia, Bacteroides, Lactobacillus, Clostridium. The PNA animals also had an increased relative abundance of bacteria associated with biosynthesis and elongation of unsaturated short chain fatty acids (SCFAs).

CONCLUSIONS

We found that prenatal exposure to excess androgen negatively impacted cardiovascular function by increasing systolic and diastolic blood pressure and decreasing heart rate. Prenatal androgen was also associated with gut microbial dysbiosis and altered abundance of bacteria involved in metabolite production of short chain fatty acids. These results suggest that early-life exposure to hyperandrogenemia in daughters of women with PCOS may lead to long-term alterations in gut microbiota and cardiometabolic function.

PBDEs Altered Gut Microbiome and Bile Acid Homeostasis in Male C57BL/6 Mice

Polybrominated diphenyl ethers (PBDEs) are persistent environmental contaminants with well characterized toxicities in host organs. Gut microbiome is increasingly recognized as an important regulator of xenobiotic biotransformation; however, little is known about its interactions with PBDEs. Primary bile acids (BAs) are metabolized by the gut microbiome into more lipophilic secondary BAs that may be absorbed and interact with certain host receptors. The goal of this study was to test our hypothesis that PBDEs cause dysbiosis and aberrant regulation of BA homeostasis. Nine-week-old male C57BL/6 conventional (CV) and germ-free (GF) mice were orally gavaged with corn oil (10 mg/kg), BDE-47 (100 μmol/kg), or BDE-99 (100 μmol/kg) once daily for 4 days (n = 3-5/group). Gut microbiome was characterized using 16S rRNA sequencing of the large intestinal content in CV mice. Both BDE-47 and BDE-99 profoundly decreased the alpha diversity of gut microbiome and differentially regulated 45 bacterial species. Both PBDE congeners increased Akkermansia muciniphila and Erysipelotrichaceae Allobaculum spp., which have been reported to have anti-inflammatory and antiobesity functions. Targeted metabolomics of 56 BAs was conducted in serum, liver, and small and large intestinal content of CV and GF mice. BDE-99 increased many unconjugated BAs in multiple biocompartments in a gut microbiota-dependent manner. This correlated with an increase in microbial 7α-dehydroxylation enzymes for secondary BA synthesis and increased expression of host intestinal transporters for BA absorption. Targeted proteomics showed that PBDEs downregulated host BA-synthesizing enzymes and transporters in livers of CV but not GF mice. In conclusion, there is a novel interaction between PBDEs and the endogenous BA-signaling through modification of the "gut-liver axis".

Salivary microbiome of an urban Indian cohort and patterns linked to subclinical inflammation

OBJECTIVE

To profile salivary microbiomes of an urban-living, healthy Indian cohort and explore associations with proinflammatory status.

METHODS

Fifty-one clinically healthy Indian subjects' salivary microbiomes were analyzed using 16S rRNA Illumina MiSeq sequencing. Community distribution was compared with salivary data from the Human Microbiome Project (HMP). Indian subjects were clustered using microbiome-based "partitioning along medoids" (PAM), and relationships of interleukin-1 beta levels with community composition were analyzed.

RESULTS

Indian subjects presented higher phylogenetic diversity than HMP. Several taxa associated with traditional societies gut microbiomes (Bacteroidales, Paraprevotellaceae, and Spirochaetaceae) were raised. Bifidobacteriaceae and Lactobacillaceae were approximately fourfold greater. A PAM cluster enriched in several Proteobacteria, Actinobacteria, and Bacilli taxa and having almost twofold higher Prevotella to Bacteroides ratio showed significant overrepresentation of subjects within the highest quartile of salivary interleukin-1 beta levels. Abiotrophia, Anaerobacillus, Micrococcus, Aggregatibacter, Halomonas, Propionivivrio, Paracoccus, Mannhemia, unclassified Bradyrhizobiaceae, and Caulobacteraceae were each significant indicators of presence in the highest interleukin-1 beta quartile. 2 OTUs representing Lactobacillus fermentum and Cardiobacterium hominis significantly correlated with interleukin-1 beta levels.

CONCLUSION

The salivary microbiome of this urban-dwelling Indian cohort differed significantly from that of a well-studied Western cohort. Specific community patterns were putatively associated with subclinical inflammation levels.

Relationships between gut microbiota, plasma metabolites, and metabolic syndrome traits in the METSIM cohort

BACKGROUND

The gut microbiome is a complex and metabolically active community that directly influences host phenotypes. In this study, we profile gut microbiota using 16S rRNA gene sequencing in 531 well-phenotyped Finnish men from the Metabolic Syndrome In Men (METSIM) study.

RESULTS

We investigate gut microbiota relationships with a variety of factors that have an impact on the development of metabolic and cardiovascular traits. We identify novel associations between gut microbiota and fasting serum levels of a number of metabolites, including fatty acids, amino acids, lipids, and glucose. In particular, we detect associations with fasting plasma trimethylamine N-oxide (TMAO) levels, a gut microbiota-dependent metabolite associated with coronary artery disease and stroke. We further investigate the gut microbiota composition and microbiota-metabolite relationships in subjects with different body mass index and individuals with normal or altered oral glucose tolerance. Finally, we perform microbiota co-occurrence network analysis, which shows that certain metabolites strongly correlate with microbial community structure and that some of these correlations are specific for the pre-diabetic state.

CONCLUSIONS

Our study identifies novel relationships between the composition of the gut microbiota and circulating metabolites and provides a resource for future studies to understand host-gut microbiota relationships.

Intestinal Dysbiosis Is Associated with Altered Short-Chain Fatty Acids and Serum-Free Fatty Acids in Systemic Lupus Erythematosus

Metabolic impairments are a frequent hallmark of systemic lupus erythematosus (SLE). Increased serum levels of free fatty acids (FFA) are commonly found in these patients, although the underlying causes remain elusive. Recently, it has been suggested that factors other than inflammation or clinical features may be involved. The gut microbiota is known to influence the host metabolism, the production of short-chain fatty acids (SCFA) playing a potential role. Taking into account that lupus patients exhibit an intestinal dysbiosis, we wondered whether altered FFA levels may be associated with the intestinal microbial composition in lupus patients. To this aim, total and specific serum FFA levels, fecal SCFA levels, and gut microbiota composition were determined in 21 SLE patients and 25 healthy individuals. The Firmicutes to Bacteroidetes (F/B) ratio was strongly associated with serum FFA levels in healthy controls (HC), even after controlling for confounders. However, this association was not found in lupus patients, where a decreased F/B ratio and increased FFA serum levels were noted. An altered production of SCFA was related to the intestinal dysbiosis in lupus, while SCFA levels paralleled those of serum FFA in HC. Although a different serum FFA profile was not found in SLE, specific FFA showed distinct patterns on a principal component analysis. Immunomodulatory omega-3 FFA were positively correlated to the F/B ratio in HC, but not in SLE. Furthermore, divergent associations were observed for pro- and anti-inflammatory FFA with endothelial activation biomarkers in lupus patients. Overall, these findings support a link between the gut microbial ecology and the host metabolism in the pathological framework of SLE. A potential link between intestinal dysbiosis and surrogate markers of endothelial activation in lupus patients is supported, FFA species having a pivotal role.