Obese Mice Losing Weight Due to trans-10,cis-12 Conjugated Linoleic Acid Supplementation or Food Restriction Harbor Distinct Gut Microbiota

A methionine-choline-deficient diet induces nonalcoholic steatohepatitis and alters the lipidome, metabolome, and gut microbiome profile in the C57BL/6J mouse

The methionine-choline-deficient (MCD) diet-induced non-alcoholic steatohepatitis (NASH) in mice is a well-established model. Our study aims to elucidate the factors influencing liver pathology in the MCD mouse model by examining physiological, biochemical, and molecular changes using histology, molecular techniques, and OMICS approaches (lipidomics, metabolomics, and metagenomics). Male C57BL/6J mice were fed a standard chow diet, a methionine-choline-sufficient (MCS) diet, or an MCD diet for 10 weeks. The MCD diet resulted in reduced body weight and fat mass, along with decreased plasma triglyceride, cholesterol, glucose, and insulin levels. However, it notably induced steatosis, inflammation, and alterations in gene expression associated with lipogenesis, inflammation, fibrosis, and the synthesis of apolipoproteins, sphingolipids, ceramides, and carboxylesterases. Lipid analysis revealed significant changes in plasma and tissues: most ceramide non-hydroxy-sphingosine lipids significantly decreased in the liver and plasma but increased in the adipose tissue of MCD diet-fed animals. Oxidized glycerophospholipids mostly increased in the liver but decreased in the adipose tissue of the MCD diet-fed group. The gut microbiome of the MCD diet-fed group showed an increase in Firmicutes and a decrease in Bacteroidetes and Actinobacteria. Metabolomic profiling demonstrated that the MCD diet significantly altered amino acid biosynthesis, metabolism, and nucleic acid metabolism pathways in plasma, liver, fecal, and cecal samples. LC-MS data indicated higher total plasma bile acid intensity and reduced fecal glycohyodeoxycholic acid intensity in the MCD diet group. This study demonstrates that although the MCD diet induces hepatic steatosis, the mechanisms underlying NASH in this model differ from those in human NASH pathology.

Taste Preferences at Different Ambient Temperatures and Associated Changes in Gut Microbiota and Body Weight in Mice

Taste, dietary choices, and gut microbiota are often analyzed as major factors of metabolic health. Populations living in cold or hot regions have different dietary habits. This study aims to investigate the potential association among ambient temperature, food taste preferences, and cecal microbiota community profiles in mice. By exposing mice to mixed diets containing sweet, sour, salty, and bitter flavors at low (4 °C) and high (37 °C) ambient temperatures, the taste preferences of mice at both ambient temperatures were in the order of saltiness > sweetness > bitterness > sourness. Exposing mice to sweet, sour, salty, and bitter diets, respectively, revealed that in a low-temperature environment, mice consuming salty (5.00 ± 1.49 g), sweet (4.99 ± 0.35 g), and sour (3.90 ± 0.61 g) diets had significantly higher weight gain compared to those consuming normal feeds (2.34 ± 0.43 g, p < 0.05). Conversely, in a high-temperature environment, no significant changes in body weight were observed among mice consuming different flavored diets (p > 0.05). In a low-temperature environment, mice fed sour and sweet diets showed a significant difference in the gut microbiota composition when compared to those fed a normal diet. A higher abundance of Lachnospiraceae, UBA1819, and Clostridiales was identified as the most significant taxa in the sour group, and a higher abundance of Ruminiclostridium was identified in the sweet group. These differences were associated with microbial pathways involved in carbohydrate metabolism, amino acid metabolism, and energy metabolism. A high-temperature environment exhibited only minor effects on the gut microbiota profile. Overall, our findings provide evidence for temperature-modulated responses to the taste, gut microbiota functions, and body weight changes in mice.

Impact of Plant-Based Dietary Fibers on Metabolic Homeostasis in High-Fat Diet Mice via Alterations in the Gut Microbiota and Metabolites

BACKGROUND

The gut microbiota contributes to metabolic disease, and diet shapes the gut microbiota, emphasizing the need to better understand how diet impacts metabolic disease via gut microbiota alterations. Fiber intake is linked with improvements in metabolic homeostasis in rodents and humans, which is associated with changes in the gut microbiota. However, dietary fiber is extremely heterogeneous, and it is imperative to comprehensively analyze the impact of various plant-based fibers on metabolic homeostasis in an identical setting and compare the impact of alterations in the gut microbiota and bacterially derived metabolites from different fiber sources.

OBJECTIVES

The objective of this study was to analyze the impact of different plant-based fibers (pectin, β-glucan, wheat dextrin, resistant starch, and cellulose as a control) on metabolic homeostasis through alterations in the gut microbiota and its metabolites in high-fat diet (HFD)-fed mice.

METHODS

HFD-fed mice were supplemented with 5 different fiber types (pectin, β-glucan, wheat dextrin, resistant starch, or cellulose as a control) at 10% (wt/wt) for 18 wk (n = 12/group), measuring body weight, adiposity, indirect calorimetry, glucose tolerance, and the gut microbiota and metabolites.

RESULTS

Only β-glucan supplementation during HFD-feeding decreased adiposity and body weight gain and improved glucose tolerance compared with HFD-cellulose, whereas all other fibers had no effect. This was associated with increased energy expenditure and locomotor activity in mice compared with HFD-cellulose. All fibers supplemented into an HFD uniquely shifted the intestinal microbiota and cecal short-chain fatty acids; however, only β-glucan supplementation increased cecal butyrate concentrations. Lastly, all fibers altered the small-intestinal microbiota and portal bile acid composition.

CONCLUSIONS

These findings demonstrate that β-glucan consumption is a promising dietary strategy for metabolic disease, possibly via increased energy expenditure through alterations in the gut microbiota and bacterial metabolites in mice.

Quinic acid regulated TMA/TMAO-related lipid metabolism and vascular endothelial function through gut microbiota to inhibit atherosclerotic

BACKGROUND

Quinic acid (QA) and its derivatives have good lipid-lowering and hepatoprotective functions, but their role in atherosclerosis remains unknown. This study attempted to investigate the mechanism of QA on atherogenesis in Apoe-/- mice induced by HFD.

METHODS

HE staining and oil red O staining were used to observe the pathology. The PCSK9, Mac-3 and SM22a expressions were detected by IHC. Cholesterol, HMGB1, TIMP-1 and CXCL13 levels were measured by biochemical and ELISA. Lipid metabolism and the HMGB1-SREBP2-SR-BI pathway were detected by PCR and WB. 16 S and metabolomics were used to detect gut microbiota and serum metabolites.

RESULTS

QA or low-frequency ABX inhibited weight gain and aortic tissue atherogenesis in HFD-induced Apoe-/- mice. QA inhibited the increase of cholesterol, TMA, TMAO, CXCL13, TIMP-1 and HMGB1 levels in peripheral blood of Apoe-/- mice induced by HFD. Meanwhile, QA or low-frequency ABX treatment inhibited the expression of CAV-1, ABCA1, Mac-3 and SM22α, and promoted the expression of SREBP-1 and LXR in the vascular tissues of HFD-induced Apoe-/- mice. QA reduced Streptococcus_danieliae abundance, and promoted Lactobacillus_intestinalis and Ileibacterium_valens abundance in HFD-induced Apoe-/- mice. QA altered serum galactose metabolism, promoted SREBP-2 and LDLR, inhibited IDOL, FMO3 and PCSK9 expression in liver of HFD-induced Apoe-/- mice. The combined treatment of QA and low-frequency ABX regulated microbe-related Glycoursodeoxycholic acid and GLYCOCHENODEOXYCHOLATE metabolism in HFD-induced Apoe-/- mice. QA inhibited TMAO or LDL-induced HCAECs damage and HMGB1/SREBP2 axis dysfunction, which was reversed by HMGB1 overexpression.

CONCLUSIONS

QA regulated the gut-liver lipid metabolism and chronic vascular inflammation of TMA/TMAO through gut microbiota to inhibit the atherogenesis in Apoe-/- mice, and the mechanism may be related to the HMGB1/SREBP2 pathway.

Prebiotic inulin ameliorates SARS-CoV-2 infection in hamsters by modulating the gut microbiome

Current treatment options for COVID-19 are limited, with many antivirals and immunomodulators restricted to the most severe cases and preventative care limited to vaccination. As the SARS-CoV-2 virus and its increasing variants threaten to become a permanent fixture of our lives, this new reality necessitates the development of cost-effective and accessible treatment options for COVID-19. Studies have shown that there are correlations between the gut microbiome and severity of COVID-19, especially with regards to production of physiologically beneficial short-chain fatty acids (SCFAs) by gut microbes. In this study, we used a Syrian hamster model to study how dietary consumption of the prebiotic inulin affected morbidity and mortality resulting from SARS-CoV-2 infection. After two weeks of observation, we discovered that inulin supplementation attenuated morbid weight loss and increased survival rate in hamster subjects. An analysis of microbiome community structure showed significant alterations in 15 genera. Notably, there were also small increases in fecal DCA and a significant increase in serum DCA, perhaps highlighting a role for this secondary bile acid in conferring protection against SARS-CoV-2. In light of these results, inulin and other prebiotics are promising targets for future investigation as preventative treatment options for COVID-19.

Metabolic effects of milk fatty acids: A literature review

Milk and dairy products are known to have a significant role in human development and tissue maintenance due to their high nutritional value. With the higher incidence of obesity and metabolic diseases, nutrition and public health authorities have recommended the intake of fat-free or low-fat dairy due to the saturated fatty acid content of whole-fat products and their effect on serum cholesterol levels. However, recent studies have questioned the association between milk fat consumption and cardiometabolic risk. This literature review aims to compile the scientific evidence of the metabolic effects of milk fatty acids in clinical and basic research studies, as well as their relationship with metabolic disorders and gut microbiota composition. Research shows that various milk fatty acids exert effects on metabolic alterations (obesity, type 2 diabetes and cardiovascular diseases) by modifying glucose homeostasis, inflammation and lipid profile-related factors. Additionally, recent studies have associated the consumption of milk fatty acids with the production of metabolites and the promotion of healthy gut microbiota. From mainly observational studies, evidence suggests that milk and dairy fatty acids are not directly linked to cardiometabolic risk, but further controlled research is necessary to clarify such findings and to assess whether dietary recommendations to choose low-fat dairy foods are necessary for the population for the prevention of obesity and cardiometabolic disease.

Comparative profiling of gut microbiota and metabolome in diet-induced obese and insulin-resistant C57BL/6J mice

Diet-based models are commonly used to investigate obesity and related disorders. We conducted a comparative profiling of three obesogenic diets HFD, high fat diet; HFHF, high fat high fructose diet; and HFCD, high fat choline deficient diet to assess their impact on the gut microbiome and metabolome. After 20 weeks, we analyzed the gut microbiota and metabolomes of liver, plasma, cecal, and fecal samples. Fecal and plasma bile acids (BAs) and fecal short-chain fatty acids (SCFAs) were also examined. Significant changes were observed in fecal and cecal metabolites, with increased Firmicutes and decreased Bacteroidetes in the HFD, HFHF, and HFCD-fed mice compared to chow and LFD (low fat diet)-fed mice. Most BAs were reduced in plasma and fecal samples of obese groups, except taurocholic acid, which increased in HFCD mice's plasma. SCFAs like acetate and butyrate significantly decreased in obesogenic diet groups, while propionic acid specifically decreased in the HFCD group. Pathway analysis revealed significant alterations in amino acid, carbohydrate metabolism, and nucleic acid biosynthesis pathways in obese mice. Surprisingly, even LFD-fed mice showed distinct changes in microbiome and metabolite profiles compared to the chow group. This study provides insights into gut microbiome dysbiosis and metabolite alterations induced by obesogenic and LFD diets in various tissues. These findings aid in selecting suitable diet models to study the role of the gut microbiome and metabolites in obesity and associated disorders, with potential implications for understanding similar pathologies in humans.

Analysis of strain, sex, and diet-dependent modulation of gut microbiota reveals candidate keystone organisms driving microbial diversity in response to American and ketogenic diets

BACKGROUND

The gut microbiota is modulated by a combination of diet, host genetics, and sex effects. The magnitude of these effects and interactions among them is important to understanding inter-individual variability in gut microbiota. In a previous study, mouse strain-specific responses to American and ketogenic diets were observed along with several QTLs for metabolic traits. In the current study, we searched for genetic variants underlying differences in the gut microbiota in response to American and ketogenic diets, which are high in fat and vary in carbohydrate composition, between C57BL/6 J (B6) and FVB/NJ (FVB) mouse strains.

RESULTS

Genetic mapping of microbial features revealed 18 loci under the QTL model (i.e., marginal effects that are not specific to diet or sex), 12 loci under the QTL by diet model, and 1 locus under the QTL by sex model. Multiple metabolic and microbial features map to the distal part of Chr 1 and Chr 16 along with eigenvectors extracted from principal coordinate analysis of measures of β-diversity. Bilophila, Ruminiclostridium 9, and Rikenella (Chr 1) were identified as sex- and diet-independent QTL candidate keystone organisms, and Parabacteroides (Chr 16) was identified as a diet-specific, candidate keystone organism in confirmatory factor analyses of traits mapping to these regions. For many microbial features, irrespective of which QTL model was used, diet or the interaction between diet and a genotype were the strongest predictors of the abundance of each microbial trait. Sex, while important to the analyses, was not as strong of a predictor for microbial abundances.

CONCLUSIONS

These results demonstrate that sex, diet, and genetic background have different magnitudes of effects on inter-individual differences in gut microbiota. Therefore, Precision Nutrition through the integration of genetic variation, microbiota, and sex affecting microbiota variation will be important to predict response to diets varying in carbohydrate composition. Video Abstract.

The role of the gut microbiome in weight-gain in schizophrenia patients treated with atypical antipsychotics: Evidence based on altered composition and function in a cross-sectional study

OBJECTIVES

We aimed to explore the interconnection between the weight-gain in schizophrenia patients with atypical antipsychotic treatment and gut microbiome.

METHODS

This study employed a cross-sectional design, encompassing a total of 88 schizophrenia patients with long-term atypical antipsychotic treatment. The 16S rRNA gene sequencing was used to identify gut microbiome contents.

RESULTS

No significant differences in alpha diversity between normal-weight and overweight schizophrenia treated with atypical antipsychotics. The beta diversity analysis showed that overweight patients clustered tightly while normal-weight patients clustered widely. For taxonomic composition, overweight patients had a lower relative abundance in Porphyromonadaceae at family level and Butyrivibrio at genus level, but higher relative abundance in Ruminococcus2 and Clostridium_XIVa at genus level than normal-weight patients. Function prediction revelated that four pathways (including Cell cycle, Non-homologous end-joining, Vibrio cholerae infection and Meiosis-yeast) were significantly different between groups. Correlation analysis indicated that Klebsiella, Butyrivibrio, Unassigned, Methanosphaera, Holdemania, Anaerotruncus were negatively, while Veillonella was positively correlated with BMI in patients.

CONCLUSION

Our findings offer evidence that perturbations in the gut microbiome composition, encompassing taxa such as Porphyromonadaceae, Butyrivibrio, Ruminococcus2, and Clostridium_XIVa, in conjunction with distinct functional pathways including Cell cycle, Non-homologous end-joining, Vibrio cholerae infection, and Meiosis-yeast, might contribute to the weight-gain in schizophrenia treated with atypical antipsychotics.

Conjugated linoleic acid (CLA) as a functional food: Is it beneficial or not?

Conjugated linoleic acid (CLA) has attracted great attention in recent years as a popular class of functional food that is broadly used. It refers to a group of geometric and positional isomers of linoleic acid (LA) with a conjugated double bond. The main natural sources of CLA are dairy products, beef and lamb, whereas only trace amounts occur naturally in plant lipids. CLA has been shown to improve various health issues, having effects on obesity, inflammatory, anti-carcinogenicity, atherogenicity, immunomodulation, and osteosynthesis. Also, compared to studies on humans, many animal researches reveal more positive benefits on health. CLA represents a nutritional avenue to improve lifestyle diseases and metabolic syndrome. Most of these effects are attributed to the two major CLA isomers [conjugated linoleic acid cis-9,trans-11 isomer (c9,t11), and conjugated linoleic acid trans-10,cis-12 isomer (t10,c12)], and their mixture (CLA mix). In contrast, adverse effects of CLA have been also reported, such as glucose homeostasis, insulin resistance, hepatic steatosis and induction of colon carcinogenesis in humans, as well as milk fat inhibition in ruminants, lowering chicken productivity, influencing egg quality and altering growth performance in fish. This review article aims to discuss the health benefits of CLA as a nutraceutical supplement and highlight the possible mechanisms of action that may contribute to its outcome. It also outlines the feasible adverse effects of CLA besides summarizing the recent peer-reviewed publications on CLA to ensure its efficacy and safety for proper application in humans.

Thyme (Thymus quinquecostatus Celak) Polyphenol-Rich Extract (TPE) Alleviates HFD-Induced Liver Injury in Mice by Inactivating the TLR4/NF-κB Signaling Pathway through the Gut-Liver Axis

Non-alcoholic fatty liver disease (NAFLD) represents a significant and urgent global health concern. Thyme (Thymus quinquecostatus Celak) is a plant commonly used in cuisine and traditional medicine in Asian countries and possesses potential liver-protective properties. This study aimed to assess the hepatoprotective effects of thyme polyphenol-rich extract (TPE) on high-fat diet (HFD)-induced NAFLD and further explore possible mechanisms based on the gut-liver axis. HFD-induced liver injury in C57 mice is markedly ameliorated by TPE supplementation in a dose-dependent manner. TPE also regulates the expression of liver lipid metabolic genes (i.e., Hmgcr, Srebp-1, Fasn, and Cyp7a1), enhancing the production of SCFAs and regulating serum metabolites by modulating gut microbial dysbiosis. Furthermore, TPE enhances the intestinal barrier function and alleviates intestinal inflammation by upregulating tight junction protein expression (i.e., ZO-1 and occluding) and inactivating the intestinal TLR4/NF-κB pathway in HFD-fed mice. Consequently, gut-derived LPS translocation to the circulation was blocked, the liver TLR4/NF-κB signaling pathway was repressed, and subsequent pro-inflammatory cytokine production was restrained. Conclusively, TPE might exert anti-NAFLD effects through the gut-liver axis and has the potential to be used as a dietary supplement for the management of NAFLD.

Maternal separation leads to dynamic changes of visceral hypersensitivity and fecal metabolomics from childhood to adulthood

We assessed dynamic changes in visceral hypersensitivity and fecal metabolomics through a mouse model of irritable bowel syndrome (IBS) from childhood to adulthood. A mouse model of IBS was constructed with maternal separation (MS) in early life. Male mice aged 25, 40, and 70 days were used. Visceral sensitivity was assessed by recording the reaction between the abdominal withdrawal reflex and colorectal distension. Metabolomics was identified and quantified by liquid chromatography-tandem mass spectrometry. The visceral sensitivity of the MS group was significantly higher than that of the non-separation (NS) group in the three age groups. The top four fecal differential metabolites in the different age groups were lipids, lipid molecules, organic heterocyclic compounds, organic acids and derivatives, and benzenoids. Five identical differential metabolites were detected in the feces and ileal contents of the MS and NS groups at different ages, namely, benzamide, taurine, acetyl-L-carnitine, indole, and ethylbenzene. Taurine and hypotaurine metabolism were the most relevant pathways at P25, whereas histidine metabolism was the most relevant pathway at P40 and P70. Visceral hypersensitivity in the MS group lasted from childhood to adulthood. The different metabolites and metabolic pathways detected in MS groups of different ages provide a theoretical basis for IBS pathogenesis.

The Antioxidant Effect of Dietary Bioactives Arises from the Interplay between the Physiology of the Host and the Gut Microbiota: Involvement of Short-Chain Fatty Acids

The maintenance of redox homeostasis is associated with a healthy status while the disruption of this mechanism leads to the development of various pathological conditions. Bioactive molecules such as carbohydrates accessible to the microbiota (MACs), polyphenols, and polyunsaturated fatty acids (PUFAs) are food components best characterized for their beneficial effect on human health. In particular, increasing evidence suggests that their antioxidant ability is involved in the prevention of several human diseases. Some experimental data indicate that the activation of the nuclear factor 2-related erythroid 2 (Nrf2) pathway-the key mechanism in the maintenance of redox homeostasis-is involved in the beneficial effects exerted by the intake of PUFAs and polyphenols. However, it is known that the latter must be metabolized before becoming active and that the intestinal microbiota play a key role in the biotransformation of some ingested food components. In addition, recent studies, indicating the efficacy of the MACs, polyphenols, and PUFAs in increasing the microbial population with the ability to yield biologically active metabolites (e.g., polyphenol metabolites, short-chain fatty acids (SCFAs)), support the hypothesis that these factors are responsible for the antioxidant action on the physiology of the host. The underlying mechanisms through which MACs, polyphenols, and PUFAs might influence the redox status have not been fully elucidated, but based on the efficacy of SCFAs as Nrf2 activators, their contribution to the antioxidant efficacy of dietary bioactives cannot be excluded. In this review, we aimed to summarize the main mechanisms through which MACs, polyphenols, and PUFAs can modulate the host's redox homeostasis through their ability to directly or indirectly activate the Nrf2 pathway. We discuss their probiotic effects and the role played by the alteration of the metabolism/composition of the gut microbiota in the generation of potential Nrf2-ligands (e.g., SCFAs) in the host's redox homeostasis.

Clostridium butyricum Prevents Dysbiosis and the Rise in Blood Pressure in Spontaneously Hypertensive Rats

Hypertension is accompanied by dysbiosis and a decrease in the relative abundance of short-chain fatty acid (SCFA)-producing bacteria. However, there is no report to examine the role of C. butyricum in blood pressure regulation. We hypothesized that a decrease in the relative abundance of SCFA-producing bacteria in the gut was the cause of spontaneously hypertensive rats (SHR)-induced hypertension. C. butyricum and captopril were used to treat adult SHR for six weeks. C. butyricum modulated SHR-induced dysbiosis and significantly reduced systolic blood pressure (SBP) in SHR (p < 0.01). A 16S rRNA analysis determined changes in the relative abundance of the mainly SCFA-producing bacteria Akkermansia muciniphila, Lactobacillus amylovorus, and Agthobacter rectalis, which increased significantly. Total SCFAs, and particularly butyrate concentrations, in the SHR cecum and plasma were reduced (p < 0.05), while C. butyricum prevented this effect. Likewise, we supplemented SHR with butyrate for six weeks. We analyzed the flora composition, cecum SCFA concentration, and inflammatory response. The results showed that butyrate prevented SHR-induced hypertension and inflammation, and the decline of cecum SCFA concentrations (p < 0.05). This research revealed that increasing cecum butyrate concentrations by probiotics, or direct butyrate supplementation, prevented the adverse effects of SHR on intestinal flora, vascular, and blood pressure.

Fructooligosaccharides attenuate non-alcoholic fatty liver disease by remodeling gut microbiota and association with lipid metabolism

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a common liver disease highly associated with metabolic diseases and gut dysbiosis. Several clinical trials have confirmed that fructooligosaccharides (FOSs) are a viable alternative treatment for NAFLD. However, the mechanisms underlying the activities of FOSs remain unclear.

METHODS

In this study, the effects of FOSs were investigated with the use of two C57BL/6 J mouse models of NAFLD induced by a high-fat, high-cholesterol (HFHC) diet and a methionine- and choline-deficient (MCD) diet, respectively. The measured metabolic parameters included body, fat, and liver weights; and blood glucose, glucose tolerance, and serum levels of glutamate transaminase, aspartate transaminase, and triglycerides. Liver tissues were collected for histological analysis. In addition, 16 S rRNA sequencing was conducted to investigate the effects of FOSs on the composition of the gut microbiota of mice in the HFHC and MCD groups and treated with FOSs.

RESULTS

FOS treatment attenuated severe metabolic changes and hepatic steatosis caused by the HFHC and MCD diets. In addition, FOSs remodeled the structure of gut microbiota in mice fed the HFHC and MCD diets, as demonstrated by increased abundances of Bacteroidetes (phylum level), Klebsiella variicola, Lactobacillus gasseri, and Clostridium perfringens (species level); and decreased abundances of Verrucomicrobia (phylum level) and the Fissicatena group (genus level). Moreover, the expression levels of genes associated with lipid metabolism and inflammation (i.e., ACC1, PPARγ, CD36, MTTP, APOC3, IL-6, and IL-1β) were down-regulated after FOS treatment.

CONCLUSION

FOSs alleviated the pathological phenotype of NAFLD via remodeling of the gut microbiota composition and decreasing hepatic lipid metabolism, suggesting that FOSs as functional dietary supplements can potentially reduce the risk of NAFLD.

Analysis of strain, sex, and diet-dependent modulation of gut microbiota reveals candidate keystone organisms driving microbial diversity in response to American and ketogenic diets

Background The gut microbiota is modulated by a combination of diet, host genetics, and sex effects. The magnitude of these effects and interactions among them is important to understanding inter-individual variability in gut microbiota. In a previous study, mouse strain-specific responses to American and ketogenic diets were observed along with several QTL for metabolic traits. In the current study, we searched for genetic variants underlying differences in the gut microbiota in response to American and ketogenic diets, which are high in fat and vary in carbohydrate composition, between C57BL/6J (B6) and FVB/NJ (FVB) mouse strains. Results Genetic mapping of microbial features revealed 18 loci under the QTL model (i.e., marginal effects that are not specific to diet or sex), 12 loci under the QTL by diet model, and 1 locus under the QTL by sex model. Multiple metabolic and microbial features map to the distal part of Chr 1 and Chr 16 along with eigenvectors extracted from principal coordinate analysis of measures of β-diversity. Bilophila , Ruminiclostridium 9 , and Rikenella (Chr 1) were identified as sex and diet independent QTL candidate keystone organisms and Rikenelleceae RC9 Gut Group (Chr 16) was identified as a diet-specific, candidate keystone organism in confirmatory factor analyses of traits mapping to these regions. For many microbial features, irrespective of which QTL model was used, diet or the interaction between diet and a genotype were the strongest predictors of the abundance of each microbial trait. Sex, while important to the analyses, was not as strong of a predictor for microbial abundances. Conclusions These results demonstrate that sex, diet, and genetic background have different magnitudes of effects on inter-individual differences in gut microbiota. Therefore, Precision Nutrition through the integration of genetic variation, microbiota, and sex affecting microbiota variation will be important to predict response to diets varying in carbohydrate composition.

Gut Microbial-Derived Short Chain Fatty Acids: Impact on Adipose Tissue Physiology

Obesity is a global public health issue and major risk factor for pathological conditions, including type 2 diabetes, dyslipidemia, coronary artery disease, hepatic steatosis, and certain types of cancer. These metabolic complications result from a combination of genetics and environmental influences, thus contributing to impact whole-body homeostasis. Mechanistic animal and human studies have indicated that an altered gut microbiota can mediate the development of obesity, leading to inflammation beyond the intestine. Moreover, prior research suggests an interaction between gut microbiota and peripheral organs such as adipose tissue via different signaling pathways; yet, to what degree and in exactly what ways this inter-organ crosstalk modulates obesity remains elusive. This review emphasizes the influence of circulating gut-derived short chain fatty acids (SCFAs) i.e., acetate, propionate, and butyrate, on adipose tissue metabolism in the scope of obesity, with an emphasis on adipocyte physiology in vitro and in vivo. Furthermore, we discuss some of the well-established mechanisms via which microbial SCFAs exert a role as a prominent host energy source, hence regulating overall energy balance and health. Collectively, exploring the mechanisms via which SCFAs impact adipose tissue metabolism appears to be a promising avenue to improve metabolic conditions related to obesity.

Actively replicating gut bacteria identified by 5-ethynyl-2'-deoxyuridine (EdU) click chemistry and cell sorting

The composition of the intestinal bacterial community is well described, but recent research suggests that the metabolism of these bacteria plays a larger role in health than which species are present. One fundamental aspect of gut bacterial metabolism that remains understudied is bacterial replication. Indeed, there exist few techniques which can identify actively replicating gut bacteria. In this study, we aimed to address this gap by adapting 5-ethynyl-2'-deoxyuridine (EdU) click chemistry (EdU-click), a metabolic labeling method, coupled with fluorescence-activated cell sorting and sequencing (FACS-Seq) to characterize replicating gut bacteria. We first used EdU-click with human gut bacterial isolates and show that many of them are amenable to this technique. We then optimized EdU-click and FACS-Seq for murine fecal bacteria and reveal that Prevotella UCG-001 and Ileibacterium are enriched in the replicating fraction. Finally, we labeled the actively replicating murine gut bacteria during exposure to cell wall-specific antibiotics in vitro. We show that regardless of the antibiotic used, the actively replicating bacteria largely consist of Ileibacterium, suggesting the resistance of this taxon to perturbations. Overall, we demonstrate how combining EdU-click and FACSeq can identify the actively replicating gut bacteria and their link with the composition of the whole community in both homeostatic and perturbed conditions. This technique will be instrumental in elucidating in situ bacterial replication dynamics in a variety of other ecological states, including colonization and species invasion, as well as for investigating the relationship between the replication and abundance of bacteria in complex communities.

The gut microbiota-artery axis: A bridge between dietary lipids and atherosclerosis?

Atherosclerotic cardiovascular disease is one of the major leading global causes of death. Growing evidence has demonstrated that gut microbiota (GM) and its metabolites play a pivotal role in the onset and progression of atherosclerosis (AS), now known as GM-artery axis. There are interactions between dietary lipids and GM, which ultimately affect GM and its metabolites. Given these two aspects, the GM-artery axis may play a mediating role between dietary lipids and AS. Diets rich in saturated fatty acids (SFAs), omega-6 polyunsaturated fatty acids (n-6 PUFAs), industrial trans fatty acids (TFAs), and cholesterol can increase the levels of atherogenic microbes and metabolites, whereas monounsaturated fatty acids (MUFAs), ruminant TFAs, and phytosterols (PS) can increase the levels of antiatherogenic microbes and metabolites. Actually, dietary phosphatidylcholine (PC), sphingomyelin (SM), and omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been demonstrated to affect AS via the GM-artery axis. Therefore, that GM-artery axis acts as a communication bridge between dietary lipids and AS. Herein, we will describe the molecular mechanism of GM-artery axis in AS and discuss the complex interactions between dietary lipids and GM. In particular, we will highlight the evidence and potential mechanisms of dietary lipids affecting AS via GM-artery axis.

Chemotherapeutic Drugs Induce Different Gut Microbiota Disorder Pattern and NOD/RIP2/NF-κB Signaling Pathway Activation That Lead to Different Degrees of Intestinal Injury

5-Fluorouracil (5-FU), irinotecan (CPT-11), oxaliplatin (L-OHP), and calcium folinate (CF) are widely used chemotherapeutic drugs to treat colorectal cancer. However, chemotherapeutic use is often accompanied by intestinal inflammation and gut microbiota disorder. Changes in gut microbiota may destroy the intestinal barrier, which contributes to the severity of intestinal injury. However, intestinal injury and gut microbiota disorder have yet to be compared among 5-FU, CPT-11, L-OHP, and CF in detail, thereby limiting the development of targeted detoxification therapy after chemotherapy. In this study, a model of chemotherapy-induced intestinal injury in tumor-bearing mice was established by intraperitoneally injecting chemotherapeutic drugs at a clinically equivalent dose. 16S rRNA gene sequencing was used to detect gut microbiota. We found that 5-FU, CPT-11, and l-OHP caused intestinal injury, inflammatory cytokine (gamma interferon [IFN-γ], tumor necrosis factor alpha [TNF-α], interleukin-1β [IL-1β], and IL-6) secretion, and gut microbiota disorder. We established a complex but clear network between the pattern of changes in gut microbiota and degree of intestinal damage induced by different chemotherapeutic drugs. L-OHP caused the most severe damage in the intestine and disorder of the gut microbiota and showed a considerable overlap of the pattern of changes in microbiota with 5-FU and CPT-11. Analysis by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt v.1.0) showed that the microbiota disorder pattern induced by 5-FU, CPT-11, and L-OHP was related to the NOD-like signaling pathway. Therefore, we detected the protein expression of the NOD/RIP2/NF-κB signaling pathway and found that L-OHP most activated this pathway. Redundancy analysis/canonical correlation analysis (RDA/CCA) revealed that Bifidobacterium, Akkermansia, Allobaculum, Catenibacterium, Mucispirillum, Turicibacter, Helicobacter, Proteus, Escherichia Shigella, Alloprevotealla, Vagococcus, Streptococcus, and "Candidatus Saccharimonas" were highly correlated with the NOD/RIP2/NF-κB signaling pathway and influenced by chemotherapeutic drugs. IMPORTANCE Chemotherapy-induced intestinal injury limits the clinical use of drugs. Intestinal injury involves multiple signaling pathways and gut microbiota disruption. Our results suggested that the degree of intestinal injury caused by different drugs of the first-line colorectal chemotherapy regimen is related to the pattern of changes in microbiota. The activation of the NOD/RIP2/NF-κB signaling pathway was also related to the pattern of changes in microbiota. l-OHP caused the most severe damage to the intestine and showed a considerable overlap of the pattern of changes in microbiota with 5-FU and CPT-11. Thirteen bacterial genera were related to different levels of intestinal injury and correlated with the NOD/RIP2/NF-κB pathway. Here, we established a network of different chemotherapeutic drugs, gut microbiota, and the NOD/RIP2/NF-κB signaling pathway. This study likely provided a new basis for further elucidating the mechanism and clinical treatment of intestinal injury caused by chemotherapy.

Recent advances and potentiality of postbiotics in the food industry: Composition, inactivation methods, current applications in metabolic syndrome, and future trends

Postbiotics are defined as "preparation of inanimate microorganisms and/or their components that confers a health benefit on the host". Postbiotics have unique advantages over probiotics, such as stability, safety, and wide application. Although postbiotics are research hotspots, the research on them is still very limited. This review provides comprehensive information on the scope of postbiotics, the preparation methods of inanimate microorganisms, and the application and mechanisms of postbiotics in metabolic syndrome (MetS). Furthermore, the application trends of postbiotics in the food industry are reviewed. It was found that postbiotics mainly include inactivated microorganisms, microbial lysates, cell components, and metabolites. Thermal treatments are the main methods to prepare inanimate microorganisms as postbiotics, while non-thermal treatments, such as ionizing radiation, ultraviolet light, ultrasound, and supercritical CO2, show great potential in postbiotic preparation. Postbiotics could ameliorate MetS through multiple pathways including the modulation of gut microbiota, the enhancement of intestinal barrier, the regulation of inflammation and immunity, and the modulation of hormone homeostasis. Additionally, postbiotics have great potential in the food industry as functional food supplements, food quality improvers, and food preservatives. In addition, the SWOT analyses showed that the development of postbiotics in the food industry exists both opportunities and challenges.

A microbiome abundant environment remodels the intestinal microbiota and improves resistance to obesity induced by chlorpyrifos in mice

There is a growing consensus that the appropriate microbiome abundant environment actuates microbiota changes to influence human health. Whether living environment reacts on the threat of contaminants and the underlying mechanism remain largely unknown. Therefore, we constructed microbiome abundant environment models, focusing on their regulatory effects on the obesity induced by the exogenous chemical chlorpyrifos (CPF) and the related mechanisms. The results uncovered that the constructed farm and woodland microbiome abundant environment could protect mice against CPF-induced obesity effectively. The microbiome abundant environment regulated CPF-induced microbiota imbalance, characterized by an increase in Lactobacillus abundance. These altered microbiotas modified the intestinal immune system by increasing the expression of Foxp3 and IL-10, and mitigated intestinal barrier injury by upregulating the expression of IL-22 and intestinal tight junction proteins. Fecal microbiota transplantation could receive similar phenotypes on alleviating CPF-induced obesity development. Our results demonstrate that the microbiome abundant environment attenuates exogenous chemical-induced health risks by remodeling the intestinal microbiota, improving the intestinal ecosystem, and preventing intestinal epithelial leakage.

Advances in research of microbiome regulation as a therapy for liver failure

The intestinal flora of the human body is complex and diverse, and the structure and composition of the intestinal micro-ecosystem formed by the intestinal flora are complicated. Studies have shown that the imbalance of the intestinal micro-ecosystem is closely related to the occurrence and development of liver failure, and the degree of intestinal microecological imbalance is significantly correlated with the severity of liver failure. Therefore, the role of intestinal microbiome regulation in the treatment of liver failure and the improvement of prognosis has increasingly attracting the attention of scholars. However, due to the complexity of the composition and structure of the intestinal flora and its mechanism of action involved in the development of liver failure, the application of intestinal microbiome regulation in the clinic is limited to a certain extent. In this paper, we review the research progress of microbiome regulation as a therapy for liver failure.

Diet-Related Changes of Short-Chain Fatty Acids in Blood and Feces in Obesity and Metabolic Syndrome

Obesity-related illnesses are one of the leading causes of death worldwide. Metabolic syndrome has been associated with numerous health issues. Short-chain fatty acids (SCFAs) have been shown to have multiple effects throughout the body, both directly as well as through specific G protein-coupled receptors. The main SCFAs produced by the gut microbiota are acetate, propionate, and butyrate, which are absorbed in varying degrees from the large intestine, with some acting mainly locally and others systemically. Diet has the potential to influence the gut microbial composition, as well as the type and amount of SCFAs produced. High fiber-containing foods and supplements increase the production of SCFAs and SCFA-producing bacteria in the gut and have been shown to have bodyweight-lowering effects. Dietary supplements, which increase SCFA production, could open the way for novel approaches to weight loss interventions. The aim of this review is to analyze the variations of fecal and blood SCFAs in obesity and metabolic syndrome through a systematic search and analysis of existing literature.

Ginsenoside Rc ameliorated atherosclerosis via regulating gut microbiota and fecal metabolites

Atherosclerosis (AS) and the accompanied cardiovascular diseases (CVDs) were the leading cause of death worldwide. Recently, the association between CVDs, gut microbiota, and metabolites had aroused increasing attention. In the study, we headed our investigation into the underlying mechanism of ginsenoside Rc (GRc), an active ingredient of ginsenosides used for the treatment of CVDs, in apolipoprotein E-deficient (ApoE^−/−) mice with high-fat diet (HFD). Seven-week-old male ApoE^−/− mice were randomly divided into four groups: the normal control (NC) group, the HFD group, the GRc group (40 mg/kg/d), and the atorvastatin (Ato) group (10 mg/kg/d). Atherosclerotic injury was evaluated by aortic lesions, serum lipid levels, and inflammatory factors. The composition of gut microbiota and fecal metabolite profile were analyzed using 16S rRNA sequence and untargeted metabolomics, respectively. The results showed that GRc significantly alleviated HFD-induced aortic lesions, reduced serum levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), tumor necrosis factor-α (TNF-α), and interleukin (IL)-6 and IL-1β, and increased high-density lipoprotein cholesterol (HFD-C) level, as well as the alteration of gut microbiota composition, function, and metabolite profile. GRc also reversed HFD change of Bacteroidetes and Firmicutes at the phylum level, Muribaculaceae, Lactobacillus, Ileibacterium, Bifidobacterium, Faecalibaculum, Oscillibacter, Blautia, and Eubacterium_coprostanoligenes_group at the genus level, and 23 key metabolites involved in taurine and hypotaurine metabolism, arginine biosynthesis, ATP-binding cassette (ABC) transporters, primary bile acid biosynthesis, purine metabolism, tricarboxylic acid (TCA) cycle, and glucagon signaling pathways. Additionally, eight differential intestinal floras at the genus level were associated with 23 key differential metabolites involving atherosclerotic injury. In conclusion, our results demonstrated that GRc ameliorated atherosclerotic injury, regulated microbial and metabolomic changes in HFD-induced ApoE^−/− mice, and suggested a potential correlation among gut microbiota, metabolites, and atherosclerotic injury regarding the mechanisms of GRc against AS.

Bacillus sp. DU-106 ameliorates type 2 diabetes by modulating gut microbiota in high-fat-fed and streptozotocin-induced mice

AIMS

Type 2 diabetes mellitus (T2D) is a chronic disease that manifests as endocrine and metabolic disorders that seriously threatening public health. This study aimed to investigate the effects of Bacillus sp. DU-106 on anti-diabetic effects and gut microbiota in C57BL/6J mice fed a high-fat diet and streptozotocin-induced T2D.

METHODS AND RESULTS

Bacillus sp. DU-106 was administered to model mice for eight consecutive weeks. Oral administration of Bacillus sp. DU-106 decreased food and water intake and alleviated body weight loss. Moreover, Bacillus sp. DU-106 imparted several health benefits to mice, including balanced blood glucose, alleviation of insulin resistance in T2D mice, and an improvement in lipid metabolism. Furthermore, Bacillus sp. DU-106 protected against liver and pancreatic impairment. Additionally, Bacillus sp. DU-106 treatment reshaped intestinal flora by enhancing gut microbial diversity and enriching the abundance of certain functional bacteria.

CONCLUSION

Collectively, these findings suggest that Bacillus sp. DU-106 can ameliorate T2D by regulating the gut microbiota.

SIGNIFICANCE AND IMPACT OF STUDY

Therefore, a novel probiotic, Bacillus sp. DU-106 may be a promising therapeutic agent for improving and alleviating T2D in mice.

Natural shikonin and acetyl-shikonin improve intestinal microbial and protein composition to alleviate colitis-associated colorectal cancer

BACKGROUND

Colorectal cancer (CRC) and inflammatory bowel disease (IBD) are the most common diseases of human digestive system. Nowadays, the influence of the inflammatory microenvironment on tumorigenesis has become a new direction, and the exploration of relative molecular mechanism will facilitate the discovery and identification of novel potential anti-cancer molecules.

METHODS

Natural shikonin (SK) and acetyl-shikonin (acetyl-SK) was administered to azoxymethane (AOM)/dextran sodium sulphate (DSS)-induced colitis-associated colorectal cancer (CAC) mice model by gavage to investigate their therapeutic effects. Moreover, fresh feces and colon tissues were collected for determining the function of SK and acetyl-SK on the gut microbes and protein expression, respectively.

RESULTS

Both SK and acetyl-SK decreased AOM/DSS-induced CAC, and regulated the intestinal flora structure in CAC mouse model. They, especially SK, improved species richness, evenness and diversity of intestinal flora, recovered the upregulated ratio of Firmicutes to Bacteroidota (F/B ratio) which symbolizes gut microbiota dysbiosis. SK and its derivative increased the beneficial bacteria g__norank_f__Muribaculaceae, Lactobacillus, Lachnospiraceae_NK4A136_Group, and reduced those harmful ones including Ileibacterium and Coriobacteriaceae UCG-002. Notably, AOM/DSS caused significant increase in the abundance of Ileibaterium valens and g__norank_f__norank_o__Clostridia_UCG-014, which were not previously reported in studies of colonic inflammation or cancer, and the disorder was reversed by 20 mg/kg of SK. In our current study, the action of SK and acetyl-SK is dose-dependent, and 20 mg/kg SK exhibited the most effective functions, even better than the positive drug mesalazine. Moreover, differential proteomics and ELISA results showed that SK could recover the increase of pro-inflammatory cytokines (including IL-1β, IL-6 and TNF-α), the upregulation of pyruvate kinase isozyme type M2 (PKM2) and some other proteins (mainly concentrated in transcriptional mis-regulation in cancer and IL-17 signaling pathways), and the downregulation of Aldh1b1-Acc3-Maoa and Μgt2b34-Aldh1a1-Aldh1a7 involved in Wnt/β-catenin signaling pathway.

CONCLUSION

Our study identified SK and acetyl-SK, especially SK, as potential preventive agents for CAC through regulating both gut microbes and pathways involved in inflammation and cancer such as Wnt/β-catenin signaling pathway.

10,12-conjugated linoleic acid supplementation improves HDL composition and function in mice

Obesity is associated with inflammation, insulin resistance, and type 2 diabetes, which are major risk factors for CVD. One dietary component of ruminant animal foods, 10,12-conjugated linoleic acid (10,12 CLA), has been shown to promote weight loss in humans. Previous work has shown that 10,12 CLA is atheroprotective in mice by a mechanism that may be distinct from its weight loss effects, but this exact mechanism is unclear. To investigate this, we evaluated HDL composition and function in obese LDL receptor (Ldlr^−/−) mice that were losing weight because of 10,12 CLA supplementation or caloric restriction (CR; weight-matched control group) and in an obese control group consuming a high-fat high-sucrose diet. We show that 10,12 CLA-HDL exerted a stronger anti-inflammatory effect than CR- or high-fat high-sucrose-HDL in cultured adipocytes. Furthermore, the 10,12 CLA-HDL particle (HDL-P) concentration was higher, attributed to more medium- and large-sized HDL-Ps. Passive cholesterol efflux capacity of 10,12 CLA-HDL was elevated, as was expression of HDL receptor scavenger receptor class B type 1 in the aortic arch. Murine macrophages treated with 10,12 CLA in vitro exhibited increased expression of cholesterol transporters Abca1 and Abcg1, suggesting increased cholesterol efflux potential of these cells. Finally, proteomics analysis revealed elevated Apoa1 content in 10,12 CLA-HDL-Ps, consistent with a higher particle concentration, and particles were also enriched with alpha-1-antitrypsin, an emerging anti-inflammatory and antiatherosclerotic HDL-associated protein. We conclude that 10,12 CLA may therefore exert its atheroprotective effects by increasing HDL-P concentration, HDL anti-inflammatory potential, and promoting beneficial effects on cholesterol efflux.

Conjugated linoleic acid ameliorates hepatic steatosis by modulating intestinal permeability and gut microbiota in ob/ob mice

Background

Conjugated linoleic acid (CLA) is an effective supplement for reducing fat mass, but its effect on hepatic steatosis remains controversial.

Objective

This study aims to evaluate the effect of CLA on liver fat accumulation, inflammation, gut microbiome, and intestinal barrier integrity.

Design

Wild-type (WT) mice and ob/ob (OB) mice were randomly divided into four groups according to the treatment with/without 1% CLA: WT, WT mice treated with CLA (WT-CLA), OB, and OB mice treated with CLA (OB-CLA). Lipid metabolism and hepatic fat accumulation were evaluated by changes in histological and biochemical parameters. Gene expressions related to liver inflammation and intestinal barrier integrity were examined. The effect of CLA on the gut microbiota population was investigated.

Results

The body weight, fatty tissue mass, and serum lipid levels of the WT-CLA group and OB-CLA group were separately lower than those of the WT group and OB group, but the livers of the WT-CLA group had more fatty lipids, higher triglyceride properties, and saturated fatty acid (FA) composition than those of the WT group, which was contrary to the effect of CLA on OB mice. Real time quantitative PCR results showed that CLA increased hepatic inflammation and intestinal permeability in the WT mice, while it significantly decreased the mRNA expression of liver TNF-α, IFN-γ, and IL-1β and markedly ameliorated intestinal tight junction proteins in the OB mice. The gut microbiota testing indicated a higher abundance of beneficial bacteria (e.g., Lachnoclostridium, Roseburia, Dubosiella, Oscillibacter, and Anaerostipes) and a lower abundance of pro-inflammatory bacteria (e.g., Tyzzerella and Alistipes) in the OB-CLA group than those of the OB group. Correlation analysis suggested that gut microbiota correlated with liver inflammation, intestinal permeability, and hepatic FA composition.

Conclusion

CLA potentially contributed to ameliorating hepatic steatosis in OB mice via modulating liver inflammation, intestinal permeability, and gut microbiota, which suggests CLA is more suitable for people with obesity or overweight.

Gut Microbiome Alterations and Hepatic Metabolic Flexibility in the Gansu Zokor, Eospalax cansus: Adaptation to Hypoxic Niches

The Gansu zokor (Eospalax cansus), a typical subterranean rodent endemic to the Chinese Loess Plateau, spends almost its whole life in its self-constructed underground burrows and has strong adaptability to ambient hypoxia. Energy adaptation is the key to supporting hypoxia tolerance, and recent studies have shown that the intestinal microbiota has an evident effect on energy metabolism. However, how the gut microbiome of Gansu zokor will change in response to hypoxia and the metabolic role played by the microbiome have not been reported. Thus, we exposed Gansu zokors to severe hypoxia of 6.5% of O2 (6 or 44 h) or moderate hypoxia of 10.5% of O2 (44 h or 4 weeks), and then analyzed 16S rRNA sequencing, metagenomic sequencing, metagenomic binning, liver carbohydrate metabolites, and the related molecular levels. Our results showed that the hypoxia altered the microbiota composition of Gansu zokor, and the relative contribution of Ileibacterium to carbohydrate metabolism became increased under hypoxia, such as glycolysis and fructose metabolism. Furthermore, Gansu zokor liver enhanced carbohydrate metabolism under the short-term (6 or 44 h) hypoxia but it was suppressed under the long-term (4 weeks) hypoxia. Interestingly, under all hypoxia conditions, Gansu zokor liver exhibited enhanced fructose-driven metabolism through increased expression of the GLUT5 fructose transporter, ketohexokinase (KHK), aldolase B (ALDOB), and aldolase C (ALDOC), as well as increased KHK enzymatic activity and fructose utilization. Overall, our results suggest that the altered gut microbiota mediates the carbohydrate metabolic pattern under hypoxia, possibly contributing to the hepatic metabolic flexibility in Gansu zokor, which leads to better adaptation to hypoxic environments.

Integrated stress response regulates GDF15 secretion from adipocytes, preferentially suppresses appetite for a high-fat diet and improves obesity

The eIF2α phosphorylation-dependent integrated stress response (ISR) is a signaling pathway that maintains homeostasis in mammalian cells exposed to various stresses. Here, ISR activation in adipocytes improves obesity and diabetes by regulating appetite in a non-cell-autonomous manner. Adipocyte-specific ISR activation using transgenic mice decreases body weight and improves glucose tolerance and obesity induced by a high-fat diet (HFD) via preferential inhibition of HFD intake. The transcriptome analysis of ISR-activated adipose tissue reveals that growth differentiation factor 15 (GDF15) expression is induced by the ISR through the direct regulation of the transcription factors ATF4 and DDIT3. Deficiency in the GDF15 receptor GFRAL abolishes the adipocyte ISR-dependent preferential inhibition of HFD intake and the anti-obesity effects. Pharmacologically, 10(E), 12(Z)-octadecadienoic acid induces ISR-dependent GDF15 expression in adipocytes and decreases the intake of the HFD. Based on our findings the specific activation of the ISR in adipocytes controls the non-cell-autonomous regulation of appetite.

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Activation of ISR in adipocytes suppresses intake of high-fat diet and prevents obesity

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ATF4 and DDIT3 induced by ISR directly regulate GDF15 expression

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GDF15-GFRAL axis mediates the control of appetite for high-fat diet by ISR activation

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One of conjugated linoleic acids induces ISR and GDF15 expression in adipocytes

The probiotic effects of AB23A on high-fat-diet-induced non-alcoholic fatty liver disease in mice may be associated with suppressing the serum levels of lipopolysaccharides and branched-chain amino acids

Alisol B 23-acetate (AB23A) is a natural triterpenoid isolated from Rhizoma alisamatis that has been widely used as a traditional Chinese medicine (TCM). Previous studies have documented the beneficial effect of AB23A on non-alcoholic fatty liver disease (NAFLD), but the functional interactions between gut microbiota and the anti-NAFLD effect of AB23A remain unclear. In this study, we investigated the benefits of experimental treatment with AB23A on gut microbiota dysbiosis in NAFLD with an obesity model. C57BL/6J mice were administrated a high-fat diet (HFD) with or without AB23A for 12 weeks. AB23A significantly improved metabolic phenotype in the HFD-fed mice. Moreover, results of 16S rRNA gene-based amplicon sequencing in each group reveled that AB23A not only reduced the abundance of the Firmicutes/Bacteroidaeota ratio and Actinobacteriota/Bacteroidaeota ratio, but regulated the abundance of the top 10 genera, including norank_f__Muribaculaceae, Lactobacillus, Ileibacterium, Turicibacter, Faecalibaculum, the Lachnospiraceae_NK4A136_group, unclassified_f__Lachnospiraceae, and norank_f__Lachnospiraceae. AB23A significantly reduced the serum levels of lipopolysaccharide and branched-chain amino acids, which are positively correlated with the abundances of Ileibacterium and Turicibacter. Moreover, AB23A led to remarkable reductions in the activation of TLR4, NF-κB, and mTOR, and upregulated the expression of tight junction proteins, including ZO-1 and occludin. These results revealed that AB23A displayed a prebiotic capacity in HFD-fed NAFLD mice.

Novel β-mannanase/GLP-1 fusion peptide high effectively ameliorates obesity in a mouse model by modifying balance of gut microbiota

We constructed a novel β-mannanase/GLP-1 fusion peptide, termed MGLP_1, and evaluated its ability to ameliorate obesity in a high-fat/high-sugar diet (HFSD)-induced mouse model. Eight-wk MGLP_1 treatment notably reduced obesity, as reflected by significant changes of body weight, serum triglyceride level, fatty liver and adipose tissue distribution. Amelioration of HFSD-induced gut dysbiosis by MGLP_1 was evidenced by reduced abundance ratio of bacterial phyla Firmicutes to Bacteroidetes, enhanced abundance of beneficial probiotic genera (Bifidobacterium, Lachnospiraceae, Ileibacterium), and reduced abundance of harmful genera (Clostridium, Romboutsia). Mechanisms of weight loss were investigated by comparing effects of treatment with MGLP_1 vs. prebiotics manno-oligosaccharides (MOS). MGLP_1 ameliorated gut microbiota imbalance by enhancing carbohydrate catabolism, whereas MOS promoted glycan synthesis and metabolism. Our findings, taken together, indicate that MGLP_1 fusion peptide has strong potential for amelioration of obesity by modifying relationships between gut microbiota and lipid and glucose metabolism.

Modulation of Adipocyte Metabolism by Microbial Short-Chain Fatty Acids

Obesity and its complications—including type 2 diabetes, cardiovascular disease, and certain cancers—constitute a rising global epidemic that has imposed a substantial burden on health and healthcare systems over the years. It is becoming increasingly clear that there is a link between obesity and the gut microbiota. Gut dysbiosis, characterized as microbial imbalance, has been consistently associated with obesity in both humans and animal models, and can be reversed with weight loss. Emerging evidence has shown that microbial-derived metabolites such as short-chain fatty acids (SCFAs)—including acetate, propionate, and butyrate—provide benefits to the host by impacting organs beyond the gut, including adipose tissue. In this review, we summarize what is currently known regarding the specific mechanisms that link gut-microbial-derived SCFAs with adipose tissue metabolism, such as adipogenesis, lipolysis, and inflammation. In addition, we explore indirect mechanisms by which SCFAs can modulate adipose tissue metabolism, such as via perturbation of gut hormones, as well as signaling to the brain and the liver. Understanding how the modulation of gut microbial metabolites such as SCFAs can impact adipose tissue function could lead to novel therapeutic strategies for the prevention and treatment of obesity.

The Effect of Trans Fatty Acids on Human Health: Regulation and Consumption Patterns

Health effects of trans fatty acids (TFAs) on human organisms can vary according to their type, structure, composition, and origin. Even though the adverse health effects of industrial TFAs (iTFAs) have been widely discussed, the health effects of natural TFAs (nTFAs) are still questionable. Hence, it is important to review the literature and provide an overall picture on the health effects of different TFAs coming from industrial and ruminant sources, underlining those types that have adverse health effects as well as suggesting methods for reducing their harmful effects. Multiple databases (PubMed, Medline, Cochrane Library, etc.) were searched with the key words "trans fatty acid sources", "ruminant", "industrial", "conjugated trans linoleic acid", "human", "coronary heart disease", "cancer", etc. Reference lists of the studies were scanned discussing the health effects of iTFAs and nTFAs. The review of the literature showed that iTFAs are found to be more harmful than ruminant-produced nTFAs. Although several beneficial effects (such as reduced risk of diabetes) for nTFAs have been observed, they should be used with caution. Since during labeling it is usually not mentioned whether the TFAs contained in food are of industrial or natural origin, the general suggestion is to reduce their consumption.

Uridine attenuates obesity, ameliorates hepatic lipid accumulation and modifies the gut microbiota composition in mice fed with a high-fat diet

Uridine (UR) is a pyrimidine nucleoside that plays an important role in regulating glucose and lipid metabolism. The aim of this study was to investigate the effect of UR on obesity, fat accumulation in liver, and gut microbiota composition in high-fat diet (HFD)-fed mice. ICR mice were, respectively, divided into 3 groups for 8 weeks, that is, control (CON, n = 12), high fat diet (HFD, n = 16), and HFD + UR groups (0.4 mg mL-1 in drinking water, n = 16). UR supplementation significantly reduced the body weight and suppressed the accumulation of subcutaneous, epididymal, and mesenteric WAT in HFD-fed mice (P < 0.05). Meanwhile, UR also decreased the lipid droplet accumulation in the liver and liver organoids (P < 0.05). In addition, UR supplementation increased bacterial diversity and Bacteroidetes abundance, and decreased the Firmicutes-to-Bacteroidetes ratio in HFD-fed mice significantly (P < 0.05). UR promoted the growth of butyrate-producing bacteria of Odoribacter, unidentified-Ruminococcaceae, Intestinimonas, Ruminiclostridium, and unidentified-Lachnospiraceae. A close correlation between several specific bacterial phyla or genera and the levels of WAT weight, hepatic TC, or hepatic TG genera was revealed through Spearman's correlation analysis. These results demonstrated that UR supplementation could be beneficial by attenuating HFD-induced obesity and nonalcoholic fatty liver disease.

Gut Immunity and Microbiota Dysbiosis Are Associated with Altered Bile Acid Metabolism in LPS-Challenged Piglets

Bacterial infections are among the major factors that cause stress and intestinal diseases in piglets. Lipopolysaccharide (LPS), a major component of the Gram-negative bacteria outer membrane, is commonly employed for inducing an immune response in normal organisms for convenience. The association between LPS stimulation and gut immunity has been reported. However, the effects of gut immunity on microbial homeostasis and metabolism of host, especially bile acid and lipid metabolism in piglets, remain unclear. Hence, in the current study, we elucidated the effect of gut immunity on microbial balance and host metabolism. Twenty-one-day-old healthy piglets (male) were randomly assigned into the CON and LPS groups. After 4 hours of treatment, related tissues and cecal contents were obtained for further analysis. The obtained results showed that stimulated LPS considerably damaged the morphology of intestinal villi and enhanced the relative expression of proinflammatory cytokines. Besides, LPS partially changed the microbial structure as indicated by β-diversity and increased operational taxonomic units (OTUs) related to Oxalobacter and Ileibacterium. Furthermore, bile acid, a large class of gut microbiota metabolites, was also assessed by many proteins related to the enterohepatic circulation of bile acids. It was also revealed that LPS markedly inhibited the mRNA and protein expression of TGR5 and FXR (bile acid receptors) in the ileum, which expressed negative feedback on bile acid de novo synthesis. Additionally, results indicated upregulated mRNA of genes associated with the production of bile acid in the liver tissues. Moreover, LPS reduced the expression of bile acid transporters in the ileum and liver tissues and further disturbed the normal enterohepatic circulation. Taken together, gut immunity and microbial dysbiosis are associated with altered bile acid metabolism in LPS-challenged piglets, which provided theoretical basis for revealing the potential mechanism of intestinal inflammation in swine and seeking nutrients to resist intestinal damage.

Ferulic Acid Ameliorates Atherosclerotic Injury by Modulating Gut Microbiota and Lipid Metabolism

Atherosclerosis is a leading cause of death worldwide. Recent studies have emphasized the significance of gut microbiota and lipid metabolism in the development of atherosclerosis. Herein, the effects and molecular mechanisms involving ferulic acid (FA) was examined in atherosclerosis using the ApoE-knockout (ApoE^-∕-, c57BL/6 background) mouse model. Eighteen male ApoE^-/- mice were fed a high-fat diet (HFD) for 12 weeks and then randomly divided into three groups: the model group, the FA (40 mg/kg/day) group and simvastatin (5 mg/kg/day) group. As results, FA could significantly alleviate atherosclerosis and regulate lipid levels in mice. Liver injury and hepatocyte steatosis induced by HFD were also mitigated by FA. FA improved lipid metabolism involving up-regulation of AMPKα phosphorylation and down-regulation of SREBP1 and ACC1 expression. Furthermore, FA induced marked structural changes in the gut microbiota and fecal metabolites and specifically reduced the relative abundance of Fimicutes, Erysipelotrichaceae and Ileibacterium, which were positively correlated with serum lipid levels in atherosclerosis mice. In conclusion, we demonstrate that FA could significantly ameliorate atherosclerotic injury, which may be partly by modulating gut microbiota and lipid metabolism via the AMPKα/SREBP1/ACC1 pathway.

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

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

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

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

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

Conjugated Fatty Acids in Muscle Food Products and Their Potential Health Benefits: A Review

Conjugated fatty acids (CFAs) are a group of positional and geometric isomers of polyunsaturated fatty acids (PUFAs) with conjugated double bonds. There are several subgroups of CFAs including conjugated linoleic acids (CLAs), conjugated linolenic acids (CLNAs), conjugated eicosapentaenoic acids (CEPAs), and conjugated docosahexaenoic acids (CDHAs). CFAs, especially CLAs, have been studied in recent years both for their health benefits and factors that affect their level in muscle food products. CFAs have been reported in numerous studies as having antitumor, antiobesity, antidiabetes, anticardiovascular disease, and modulating immune system effects. These biological activies are involved in changes of lipid peroxidation and energy expenditure, as well as inhibitory effects on the hormone receptor, lipid metabolism, lipoprotein lipase activity, and adiponectin production. A large body of studies has revealed that the diet, processing, storage conditions, slaughter season, and age are common factors that affect CFA content in muscle food products, as detailed in this review. Recommendations are made regarding animal farming and meat product processing to obtain high CFA content meat products and to optimize the benefits of CFA for health promotion.

Role of the Microbiome in Mediating Health Effects of Dietary Components

Numerous recent observation and intervention studies suggest that the microbiota in the gut and oral cavity play important roles in host physiology, including disease development and progression. Of the many environmental factors involved, dietary components play a pivotal role in shaping the microbiota community and function, thus eliciting beneficial or detrimental consequences on host health. The microbiota affect human physiology by altering the chemical structures of dietary components, thus creating new biological properties and modifying their lifetime and bioavailability. This review will describe the causal mechanisms between the microbiota and some specific bacterial species and diet components providing health benefits and how this knowledge could be incorporated in dietary strategies for improving human health.

Current Evidence to Propose Different Food Supplements for Weight Loss: A Comprehensive Review

The use of food supplements for weight loss purposes has rapidly gained popularity as the prevalence of obesity increases. Navigating through the vast, often low quality, literature available is challenging, as is providing informed advice to those asking for it. Herein, we provide a comprehensive literature revision focusing on most currently marketed dietary supplements claimed to favor weight loss, classifying them by their purported mechanism of action. We conclude by proposing a combination of supplements most supported by current evidence, that leverages all mechanisms of action possibly leading to a synergistic effect and greater weight loss in the foreseen absence of adverse events. Further studies will be needed to confirm the weight loss and metabolic improvement that may be obtained through the use of the proposed combination.

Gut Microbiome and Metabolome Response of Pu-erh Tea on Metabolism Disorder Induced by Chronic Alcohol Consumption

This study investigated the protective effects of pu-erh tea extract (PTE) on alcohol-induced microbiomic and metabolomic disorders. In chronic alcohol-exposed mice, PTE ameliorated chronic alcoholic consumption-induced oxidative stress, inflammation, lipid accumulation, and liver and colon damage through modulating microbiomic and metabolomic responses. PTE restored the alcohol-induced fecal microbiota dysbiosis by elevating the relative abundance of potentially beneficial bacteria, for example, Bifidobacterium and Allobaculum, and decreasing the relative abundance of potentially harmful bacteria, for example, Helicobacter and Bacteroides. The alcohol-induced metabolomic disorder was modulated by PTE, which was characterized by regulations of lipid metabolism (sphingolipid, glycerophospholipid, and linoleic acid metabolism), amino acid metabolism (phenylalanine and tryptophan metabolism), and purine metabolism. Besides, the bacterial metabolites of phytochemicals in PTE might contribute to the protective effects of PTE. Overall, PTE could be a functional beverage to treat chronic alcohol consumption-induced microbiomic and metabolomic disorders.

Prebiotic Properties of Green and Dark Tea Contribute to Protective Effects in Chemical-Induced Colitis in Mice: A Fecal Microbiota Transplantation Study

Green and dark tea extract (GTE/DTE) ameliorate chemical-induced colitis in mice; however, the role of gut microbiota in the anticolitis effects of green and dark tea in mice remains unclear. This study aims to explore the role of modulations in gut microbes mediated by green and dark tea in colitis mice by fecal microbiota transplantation (FMT). Our results indicated that GTE and DTE (5 mg/kg bodyweight/day for 4 weeks) exhibited prebiotic effects on the donor mice. Moreover, the FMT treatments (transferring the microbiota daily from the 1 g/kg bodyweight fecal sample to each recipient) indicated that, compared with the fecal microbiota from the normal diet-treated donor mice, the fecal microbiota from the GTE- and DTE-treated donor mice significantly ameliorate colitis-related symptoms (e.g., loss of bodyweight, colonic inflammation, loss of barrier integrity, and gut microbiota dysbiosis) and downregulated the TLR4/MyD88/NF-κB pathway. Collectively, GTE and DTE ameliorate chemical-induced colitis by modulating gut microbiota.

Gut Microbial-Derived Metabolomics of Asthma

In this review, we discuss gut microbial-derived metabolites involved with the origins and pathophysiology of asthma, a chronic respiratory disease that is influenced by the microbiome. Although both gut and airway microbiomes may be important in asthma development, we focus here on the gut microbiome and metabolomic pathways involved in immune system ontogeny. Metabolite classes with existing evidence that microbial-derived products influence asthma risk include short chain fatty acids, polyunsaturated fatty acids and bile acids. While tryptophan metabolites and sphingolipids have known associations with asthma, additional research is needed to clarify the extent to which the microbiome contributes to the effects of these metabolites on asthma. These metabolite classes can influence immune function in one of two ways: (i) promoting growth or maturity of certain immune cell populations or (ii) influencing antigenic load by enhancing the number or species of specific bacteria. A more comprehensive understanding of how gut microbes and metabolites interact to modify asthma risk and morbidity will pave the way for targeted diagnostics and treatments.

Metagenomics approach to the intestinal microbiome structure and function in high fat diet-induced obesity in mice fed with conjugated linoleic acid (CLA)

In this study, a high fat diet induced obesity mouse model (DIO) was used to investigate the modulatory effect of high purity conjugated linoleic acid (CLA) on the intestinal microbiota.

Ethanol extract of propolis prevents high-fat diet-induced insulin resistance and obesity in association with modulation of gut microbiota in mice

Propolis has beneficial effects anti-inflammatory, anti-diabetes and anti-obesity in human or murine models, but its mechanism has not been fully elucidated. This study was to investigate the effects of ethanol extract of propolis (EEP) on the gut microbiota, and to analyze the associations between these alterations of gut microbiota and insulin resistance and obesity in high fat diet (HFD)-fed mice. Male C57BL/6J mice were fed with chow diet, high-fat diet, and high-fat diet supplemented with 1% EEP or 2%EEP. EEP supplementation reduced HFD-induced weight gain and liver fat accumulation, proinflammatory cytokines and insulin resistance, and improved glucose tolerance and lipid profile. Meanwhile, EEP supplementation in HFD-fed mice increased anti-obesity and anti-inflammatory bacteria such as genera Roseburia and Intestinimonas and species Parabacteroides goldsteinii and Parabacteroides distasonis, and reduced pro-inflammatory bacteria such as genera Faecalibaculum and Prevotella and species Bacteroides vulgatus. These dominant bacterial taxa altered by EEP were significantly associated with the metabolic parameters of insulin resistance and obesityin HFD-fed mice. The results in this study indicated that EEP reduced HFD-induced obesity and insulin resistant, which may be mediated by modulating the composition and function of gut microbiota.

Metabolic and gut microbiome changes following GLP-1 or dual GLP-1/GLP-2 receptor agonist treatment in diet-induced obese mice

Enteroendocrine L-cell derived peptide hormones, notably glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2), have become important targets in the treatment of type 2 diabetes, obesity and intestinal diseases. As gut microbial imbalances and maladaptive host responses have been implicated in the pathology of obesity and diabetes, this study aimed to determine the effects of pharmacologically stimulated GLP-1 and GLP-2 receptor function on the gut microbiome composition in diet-induced obese (DIO) mice. DIO mice received treatment with a selective GLP-1 receptor agonist (liraglutide, 0.2 mg/kg, BID) or dual GLP-1/GLP-2 receptor agonist (GUB09–145, 0.04 mg/kg, BID) for 4 weeks. Both compounds suppressed caloric intake, promoted a marked weight loss, improved glucose tolerance and reduced plasma cholesterol levels. 16S rDNA sequencing and deep-sequencing shotgun metagenomics was applied for comprehensive within-subject profiling of changes in gut microbiome signatures. Compared to baseline, DIO mice assumed phylogenetically similar gut bacterial compositional changes following liraglutide and GUB09-145 treatment, characterized by discrete shifts in low-abundant species and related bacterial metabolic pathways. The microbiome alterations may potentially associate to the converging biological actions of GLP-1 and GLP-2 receptor signaling on caloric intake, glucose metabolism and lipid handling.