Associations between hepatic miRNA expression, liver triacylglycerols and gut microbiota during metabolic adaptation to high-fat diet in mice

The direct and indirect inhibition of proinflammatory adipose tissue macrophages by acarbose in diet-induced obesity

Inflammation is critical for obesity and obesity-induced insulin resistance (IR). In this study, we reveal the function and mechanism of acarbose on adipose tissue macrophage (ATM)-mediated inflammation in obesity and obesity-induced IR. First, acarbose enhances the abundance of propionic acid-producing Parasutterella, therefore indirectly inhibiting the survival and proinflammatory function of M1-like ATMs via GPR43. Most interestingly, acarbose can directly inhibit M1-like ATM-mediated inflammation through GPR120. Diet-induced obese mice exhibit nitrobenzoxadiazoles (NBD) fluorescence-labeled ATMs, but lean mice that also orally received NBD fluorescence-labeled acarbose do not exhibit NBD fluorescence-labeled ATMs. This direct inhibition of macrophages by acarbose is validated in mouse and human macrophages in vitro. In conclusion, our study reveals that acarbose directly and indirectly inhibits proinflammatory macrophage phenotype, which contributes to the improvement of obesity and obesity-induced IR. The understanding of the immune regulatory effects of acarbose may extend its potential for further therapeutic applications.

Interplay between gut microbiome, host genetic and epigenetic modifications in MASLD and MASLD-related hepatocellular carcinoma

Metabolic dysfunction-associated steatotic liver disease (MASLD) encompasses a wide spectrum of liver injuries, ranging from hepatic steatosis, metabolic dysfunction-associated steatohepatitis (MASH), fibrosis, cirrhosis to MASLD-associated hepatocellular carcinoma (MASLD-HCC). Recent studies have highlighted the bidirectional impacts between host genetics/epigenetics and the gut microbial community. Host genetics influence the composition of gut microbiome, while the gut microbiota and their derived metabolites can induce host epigenetic modifications to affect the development of MASLD. The exploration of the intricate relationship between the gut microbiome and the genetic/epigenetic makeup of the host is anticipated to yield promising avenues for therapeutic interventions targeting MASLD and its associated conditions. In this review, we summarise the effects of gut microbiome, host genetics and epigenetic alterations in MASLD and MASLD-HCC. We further discuss research findings demonstrating the bidirectional impacts between gut microbiome and host genetics/epigenetics, emphasising the significance of this interconnection in MASLD prevention and treatment.

Gut Microbiota-microRNA Interactions and Obesity Pathophysiology: A Systematic Review of Integrated Studies

Obesity is the fifth leading cause of death globally and its comorbidities put a high burden on societies and cause disability. In this review, we aim to summarize the interactions and crosstalk between gut microbiota and micro-RNA (miRNA) in obesity. We searched for the relevant literature through PubMed, Web of Science, Scopus, and Science Direct. The study design is registered in the international prospective register of systematic reviews (Prospero). According to the inclusion criteria, eight studies were eligible for assessment (two studies including human subjects and six studies including animal subjects). We report that the interactions of miRNA and gut microbiota in the context of obesity are diverse and in some cases tissue specific. However, the interactions mediate obesity-associated pathways including the inflammatory response, oxidative stress, insulin signaling, gut permeability, and lipogenesis. To mention the most meaningful results, the expression of adipose tissue miRNA-378a-3p/5p was associated with Bifidobacterium and Akkermansia abundance, the expression of hepatic miRNA-34a was related to the Firmicutes phylum, and the expression of miRNA-122-5p and miRNA-375 was associated with the Bacteroides genus. miRNA-microbiota-associated pathological pathways seem to provide an intricate, but promising field for future research directed toward the treatment of obesity and its comorbidities.

Gut microbiota causally impacts adrenal function: a two-sample mendelian randomization study

Some studies have reported that the gut microbiota can influence adrenal-related hormone levels. However, the causal effects of the gut microbiota on adrenal function remain unknown. Therefore, we employed a two-sample Mendelian randomization (MR) study to systematically investigate the impact of gut microbiota on the function of different regions of the adrenal gland. The summary statistics for gut microbiota and adrenal-related hormones used in the two-sample MR analysis were derived from publicly available genome-wide association studies (GWAS). In the MR analysis, inverse variance weighting (IVW) was used as the primary method, with MR-Egger, weighted median, and cML-MA serving as supplementary methods for causal inference. Sensitivity analyses such as the MR-Egger intercept test, Cochran's Q test, and leave-one-out analysis were used to assess pleiotropy and heterogeneity. We identified 27 causal relationships between 23 gut microbiota and adrenal function using the IVW method. Among these, Sellimonas enhanced the function of the adrenal cortex reticularis zone (beta = 0.008, 95% CI: 0.002-0.013, P = 0.0057). The cML-MA method supported our estimate (beta = 0.009, 95% CI: 0.004-0.013, P = 2 × 10- 4). Parasutterella, Sutterella, and Anaerofilum affect the functioning of different regions of the adrenal gland. Notably, pleiotropy was not observed. Our findings revealed that the gut microbiota is causally associated with adrenal function. This enhances our understanding of the gut-microbiota-brain axis and provides assistance in the early diagnosis and treatment of adrenal-related diseases in clinical practice.

Unlocking the potential: How acupuncture reshapes the liver-centered lipid metabolism pattern to fight obesity

Obesity, a widespread global health issue, is frequently linked to disrupted lipid metabolism, resulting in excessive accumulation of adipose tissue and associated health complications. Acupuncture, a traditional Chinese medical modality, has exhibited potential as a viable intervention for addressing obesity. The underlying mechanism proposed involves the stimulation of specific acupoints to exert a regulatory influence on hepatic function. The liver has a central role in lipid metabolism, including processes such as lipid synthesis, storage and distribution. Acupuncture is believed to enhance the liver's efficiency in processing lipids, thereby reducing lipid accumulation and improving metabolic functions. Research indicates that acupuncture can influence the expression of certain genes and proteins involved in lipid metabolism in the liver. This includes upregulating genes that promote lipid breakdown and oxidation, and downregulating those involved in lipid synthesis. Additionally, acupuncture has been shown to improve insulin sensitivity, which is crucial for the regulation of lipid metabolism. Furthermore, the potential anti-inflammatory effects of acupuncture may play a significant role in its efficacy for the treatment of obesity. The presence of chronic inflammation has been strongly associated with metabolic disorders such as obesity. Through its ability to mitigate inflammation, acupuncture can potentially aid in the restoration of lipid metabolism and the reduction of body weight. Moreover, the amelioration of hepatic oxidative stress represents another mechanism by which acupuncture may contribute to the reduction of lipid deposition. Notably, the liver, being the primary site of lipid metabolism, maintains communication with various organs including the brain, adipose tissue, skeletal muscle and intestines. This perspective opens new avenues for the treatment of obesity, emphasizing the importance of holistic approaches in managing complex metabolic disorders. Please cite this article as: Yang SR, Chen L, Luo D, Wang YY, Liang FX. Unlocking the potential: How acupuncture reshapes the liver-centered lipid metabolism pattern to fight obesity. J Integr Med. 2024; 22(5): 523-532.

Gut-Liver-Pancreas Axis Crosstalk in Health and Disease: From the Role of Microbial Metabolites to Innovative Microbiota Manipulating Strategies

The functions of the gut are closely related to those of many other organs in the human body. Indeed, the gut microbiota (GM) metabolize several nutrients and compounds that, once released in the bloodstream, can reach distant organs, thus influencing the metabolic and inflammatory tone of the host. The main microbiota-derived metabolites responsible for the modulation of endocrine responses are short-chain fatty acids (SCFAs), bile acids and glucagon-like peptide 1 (GLP-1). These molecules can (i) regulate the pancreatic hormones (insulin and glucagon), (ii) increase glycogen synthesis in the liver, and (iii) boost energy expenditure, especially in skeletal muscles and brown adipose tissue. In other words, they are critical in maintaining glucose and lipid homeostasis. In GM dysbiosis, the imbalance of microbiota-related products can affect the proper endocrine and metabolic functions, including those related to the gut-liver-pancreas axis (GLPA). In addition, the dysbiosis can contribute to the onset of some diseases such as non-alcoholic steatohepatitis (NASH)/non-alcoholic fatty liver disease (NAFLD), hepatocellular carcinoma (HCC), and type 2 diabetes (T2D). In this review, we explored the roles of the gut microbiota-derived metabolites and their involvement in onset and progression of these diseases. In addition, we detailed the main microbiota-modulating strategies that could improve the diseases' development by restoring the healthy balance of the GLPA.

A Novel Foodstuff Mixture Improves the Gut-Liver Axis in MASLD Mice and the Gut Microbiota in Overweight/Obese Patients

Microbial community control is crucial for maintaining homeostasis of the gut-liver axis in metabolic dysfunction-associated steatotic liver disease (MASLD). Here, we show that supplementation with a mixture of Mexican foodstuffs (MexMix)-Opuntia ficus indica (nopal), Theobroma cacao (cocoa) and Acheta domesticus (crickets)-enriches several beneficial taxa in MASLD mice and overweight/obese humans. Thus, MexMix induces an important prebiotic effect. In mice, a restoration of intestinal health was observed due to the increased short-chain fatty acids (SCFAs) and intestinal crypt depth, Ocln and Cldn1 expression, and decreased Il6 and Tnfa expression. MexMix significantly reduced steatosis in the mice's liver and modified the expression of 1668 genes. By PCR, we corroborated a Tnfa and Pparg decrease, and a Cat and Sod increase. In addition, MexMix increased the hepatic NRF2 nuclear translocation and miRNA-34a, miRNA-103, and miRNA-33 decline. In overweight/obese humans, MexMix improved the body image satisfaction and reduced the fat intake. These findings indicate that this new food formulation has potential as a therapeutic approach to treat conditions associated with excessive consumption of fats and sugars.

Role of MicroRNAs in Dietary Interventions for Obesity and Obesity-Related Diseases

Obesity and related metabolic syndromes pose a serious threat to human health and quality of life. A proper diet is a safe and effective strategy to prevent and control obesity, thus maintaining overall health. However, no consensus exists on the connotations of proper diet, and it is attributed to various factors, including "nutritional dark matter" and the "matrix effect" of food. Accumulating evidence confirms that obesity is associated with the in vivo levels of miRNAs, which serve as potential markers and regulatory targets for obesity onset and progression; food-derived miRNAs can regulate host obesity by targeting the related genes or gut microbiota across the animal kingdom. Host miRNAs mediate food nutrient-gut microbiota-obesity interactions. Thus, miRNAs are important correlates of diet and obesity onset. This review outlines the recent findings on miRNA-mediated food interventions for obesity, thereby elucidating their potential applications. Overall, we provide new perspectives and views on the evaluation of dietary nutrition, which may bear important implications for dietary control and obesity prevention.

Effects of alcohol on the symptoms of gouty arthritis and taxonomic structure of gut microbiota in C57BL/6 mice

Gout is an acute arthritis caused by the elevated levels of serum uric acid (UA), and its prevalence has been rapidly increasing. Alcohol abuse could lead to a series of health problems. Multiple pieces of evidence suggest that alcohol intake affects the development and progression of gout, while the gut microbiota plays an important role in the development of gout and the long-term alcohol consumption could affect the stability of the gut microbiota. This study aimed to explore the effects of alcohol intake at different concentrations on gouty arthritis based on the gut microbiota. We investigated the effects of different concentrations of alcohol on gouty arthritis in mouse models of acute gouty arthritis established by injection of monosodium urate (MSU) crystals into C57BL/6 mice. The results indicated that the high-alcohol consumption not only exacerbated joint swelling and pain, increased the levels of UA, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), but also showed dramatic effects on the composition and structure of the gut microbiota in gouty mice. Two key microorganisms, Parasutterella and Alistipes, could aggravate gout symptoms through lipopolysaccharide biosynthesis, riboflavin metabolism, phenylalanine metabolism, and arginine and proline metabolisms. In conclusion, our study suggested that high-concentrations of alcohol altered the gut microbiota structure in gouty mice induced by MSU crystals, which could exacerbate gouty symptoms by enhancing pro-inflammatory pathways.

Intratumor microbiota: Occult participants in the microenvironment of multiple myeloma

More recently, microbiota was detected in several tumorous tissues including multiple myeloma (MM), but the roles of which is still under-studied as paucity of research on tumor biology. Moreover, we also detected the presence of microbiota in the bone marrow of patients with MM by 2bRAD-M sequencing technology, which is an incurable hematological malignancy characterized by accumulation of abnormal plasma cells in the bone marrow. However, the roles of intratumor microbiota in tumor disease remains poorly understood. In this review, we critically reviewed recent literature about microbiota in the tumorigenesis and progression of MM. Importantly, we proposed that the emergence of microbiota in the microenvironment of multiple myeloma may be attributed to microbial dysbiosis and impaired intestinal barrier, due to the increased prevalence of MM in patients with obesity and diabetes, of which the characteristic phenotype is gut microbial dysbiosis and impaired intestinal barrier. When the intestinal barrier is damaged, dysbiotic microbiota and their metabolites, as well as dysregulated immune cells, may participate in the reshaping of the local immune microenvironment, and play pivotal roles in the tumorigenesis and development of multiple myeloma, probably by migrating to the bone marrow microenvironment from intestine. We also discuss the emerging microbiological manipulation strategies to improve long-term outcomes of MM, as well as the prospective of the state-of-the-art techniques to advance our knowledge about the biological implication in the microbiome in MM.

d-Allulose Supplementation Prevents Diet-Induced Hepatic Lipid Accumulation via miR-130-Mediated Regulation in C57BL/6 Mice

SCOPE

d-allulose is a low-calorie rare sugar. It has been reported that d-allulose supplementation significantly inhibits diet-induced hepatic fat accumulation. However, the underlying molecular mechanisms remain unclear. This study elucidates the mechanism underlying the suppressive effect of d-allulose on hepatic fat accumulation in terms of miRNA regulation.

METHODS AND RESULTS

Male C57BL/6 mice are divided into three experimental groups-normal diet and distilled water (CC group), high-fat diet (HFD) and distilled water (HC group), and HFD and 5% d-allulose solution (HA group)-and fed the respective diets for 8 weeks. Weight gain is significantly lower in the HA group than that in the HC group, although the caloric intake is the same in both. Histological analysis of liver tissues reveals excessive lipid accumulation in the HC group; this is greatly attenuated in the HA group. Real-time PCR and western blot analyses demonstrate that, compared to the HC group, the HA group exhibits decreased hepatic PPARγ and CD36 expression. Hepatic miR-130 expression levels are higher in the HA group than those in the CC and HC groups.

CONCLUSIONS

These results indicate that miRNA changes associated with PPARγ may underlie the suppression of hepatic lipid accumulation induced by d-allulose intake.

Topography of respiratory tract and gut microbiota in mice with influenza A virus infection

Introduction

Influenza A virus (IAV)-induced dysbiosis may predispose to severe bacterial superinfections. Most studies have focused on the microbiota of single mucosal surfaces; consequently, the relationships between microbiota at different anatomic sites in IAV-infected mice have not been fully studied.

Methods

We characterized respiratory and gut microbiota using full-length 16S rRNA gene sequencing by Nanopore sequencers and compared the nasopharyngeal, oropharyngeal, lung and gut microbiomes in healthy and IAV-infected mice.

Results

The oropharyngeal, lung and gut microbiota of healthy mice were dominated by Lactobacillus spp., while nasopharyngeal microbiota were comprised primarily of Streptococcus spp. However, the oropharyngeal, nasopharyngeal, lung, and gut microbiota of IAV-infected mice were dominated by Pseudomonas, Escherichia, Streptococcus, and Muribaculum spp., respectively. Lactobacillus murinus was identified as a biomarker and was reduced at all sites in IAV-infected mice. The microbiota composition of lung was more similar to that of the nasopharynx than the oropharynx in healthy mice.

Discussion

These findings suggest that the main source of lung microbiota in mice differs from that of adults. Moreover, the similarity between the nasopharyngeal and lung microbiota was increased in IAV-infected mice. We found that IAV infection reduced the similarity between the gut and oropharyngeal microbiota. L. murinus was identified as a biomarker of IAV infection and may be an important target for intervention in post-influenza bacterial superinfections.

Alterations of gut microbiota and cytokines in elevated serum diamine oxidase disorder

The present study aimed to explore gut microbiota alterations and host cytokine responses in a population with elevated serum diamine oxidase (DAO) disorder. A total of 53 study participants were included in this study, segregated into 2 groups: subjects with high-level DAO (DAO-H, n = 22) subjects with normal DAO level (DAO-N, n = 31). We investigated the clinical and demographic parameters of study participants. The fecal bacterial communities and serum cytokines in 2 groups were assessed by 16S ribosomal RNA gene sequencing and immunoassay. High-pressure liquid chromatography was used to determine hemoglobin Alc. Flow cytometry was used to find the cytokine level in the blood serum. There is no difference in age, total cholesterol (TCHO), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), hemoglobin Alc, fasting plasma glucose (FPG) and homocysteine between the 2 groups. No significant difference were found in α-diversity between the 2 groups, however, the gut microbiota of subjects in DAO-H were characterized by marked interindividual differences, decreased abundance of Phocaeicola, Lachnospira, Bacteroides, Alistipes, Agathobacter, Lachnospira and Bactetoides and increased abundances of Mediterraneibacter, Blautia, Faecallibacterium, Agathobacter, and Parasutterella. Furthermore, the cytokines were no related to the DAO level in both groups and exhibited no significant differences between DAO-H and DAO-N. This study adds a new dimension to our understanding of the DAO and gut microbiota, and revealed that an increase in the DAO level in the intestinal mucosa could alter the gut microbiota composition, which can cause gut-related complications. Research is needed to extensively evaluate downstream pathways and provide possible protective or treatment measures pertaining to relevant disorders.

In vitro fermentation of Bangia fusco-purpurea polysaccharide by human gut microbiota and the protective effects of the resultant products on Caco-2 cells from lipopolysaccharide-induced injury

Polysaccharide extracted from red seaweed Bangia fusco-purpurea (BFP) is a novel sulfated galactan, differed from agarans and carrageenans in fine structure. In this study, in vitro fermentation characteristics of BFP by human gut microbiota and its protective effect on lipopolysaccharide (LPS)-induced injury in Caco-2 cells were investigated. Our results showed that BFP was mainly degraded at transverse colon for 18 h fermentation by gut microbiota with reduced molecular weight. Meanwhile, BFP fermentation was associated with increased short-chain fatty acids (SCFAs) as compared to control group, especially acetic acid was increased to 129.53 ± 0.24 from 82.14 ± 0.23 mmol/L, and butyric acid was up to 1.56 ± 0.004 from 0.62 ± 0.01 mmol/L. Furthermore, BFP promoted abundances of Bacteroidetes and Firmicutes, while decreased numbers of Proteobacteria. The up-regrated beneficial differential metabolites were SCFAs, L-proline, arginine, folic acid, pyridoxamine, thiamine, etc. (p < 0.05), and their related metabolic pathways mainly included mTOR, arginine biosynthesis, and vitamin metabolism. Notably, BFP fermentation products at transverse colon significantly restored cell viability of LPS-treated Caco-2 cells from 73.79 ± 0.48 % to 93.79-99.64 %, which might be caused by increased beneficial differential metabolites (e.g., SCFAs). Our findings suggest that BFP has prebiotic potential and can enhance gut health.

Gut microbiome in gastrointestinal cancer: a friend or foe?

The impact of the gut microbiome on host health is becoming increasingly recognized. To date, there is growing evidence that the complex characteristics of the microbial community play key roles as potential biomarkers and predictors of responses in cancer therapy. Many studies have shown that altered commensal bacteria lead to cancer susceptibility and progression in diverse pathways. In this review, we critically assess the data for gut microbiota related to gastrointestinal cancer, including esophageal, gastric, pancreatic, colorectal cancer, hepatocellular carcinoma and cholangiocarcinoma. Importantly, the underlying mechanisms of gut microbiota involved in cancer occurrence, prevention and treatment are elucidated. The purpose of this review is to provide novel insights for applying this understanding to the development of new therapeutic strategies in gastrointestinal cancer by targeting the microbial community.

Diet-gut microbiota-epigenetics in metabolic diseases: From mechanisms to therapeutics

The prevalence of metabolic diseases, including obesity, dyslipidemia, type 2 diabetes mellitus (T2DM), and non-alcoholic fatty liver disease (NAFLD), is a severe burden in human society owing to the ensuing high morbidity and mortality. Various factors linked to metabolic disorders, particularly environmental factors (such as diet and gut microbiota) and epigenetic modifications, contribute to the progression of metabolic diseases. Dietary components and habits regulate alterations in gut microbiota; in turn, microbiota-derived metabolites, such as short-chain fatty acids (SCFAs), are influenced by diet. Interestingly, diet-derived microbial metabolites appear to produce substrates and enzymatic regulators for epigenetic modifications (such as DNA methylation, histone modifications, and non-coding RNA expression). Epigenetic changes mediated by microbial metabolites participate in metabolic disorders via alterations in intestinal permeability, immune responses, inflammatory reactions, and insulin resistance. In addition, microbial metabolites can trigger inflammatory immune responses and microbiota dysbiosis by directly binding to G-protein-coupled receptors (GPCRs). Hence, diet-gut microbiota-epigenetics may play a role in metabolic diseases. However, their complex relationships with metabolic diseases remain largely unknown and require further investigation. This review aimed to elaborate on the interactions among diet, gut microbiota, and epigenetics to uncover the mechanisms and therapeutics of metabolic diseases.

Natural Garlic Organosulfur Compounds Prevent Metabolic Disorder of Lipid and Glucose by Increasing Gut Commensal Bacteroides acidifaciens

A number of reports of the effects of garlic on gut microbiota revealed that the active garlic organosulfur compounds (OSCs) are destabilized by the action of alliinase during garlic preparation. In this study, garlic alliinase was deactivated to obtain stable garlic OSCs. Experiments with C57BL/6J mice fed with lipid and glucose metabolic disorder-inducing Western diet (WD) revealed that stable garlic OSCs prevented the disorder by increasing the relative abundance of gut Bacteroides acidifaciens. Molecular analysis indicated that garlic OSCs inhibited dyslipidemia and fatty liver by increasing taurine and subsequently promoting hepatic fatty acid β-oxidation. In parallel, garlic OSCs could meliorate glucose homeostasis by inhibiting dipeptidyl peptidase-4 (DPP-4) and hepatic gluconeogenesis. In vitro bacterial culture experiments revealed that garlic OSCs directly increased the growth of gut Bacteroides acidifaciens. The results of this study demonstrate that the molecular mechanism of the preventive effect of garlic OSCs on the WD-induced metabolic disorder is attributed to the enhanced growth of Bacteroides acidifaciens and the consequent increase in taurine.

The Potential Role of Gut Microbial-Derived Exosomes in Metabolic-Associated Fatty Liver Disease: Implications for Treatment

The prevalence and incidence of metabolic-associated fatty liver disease (MAFLD), a clinically heterogeneous disease whose primary clinical therapies include dietary control and exercise therapy, is increasing worldwide and constitutes a significant medical burden. Gut microbes influence the physiopathological processes of the liver through different mechanisms based on the gut-liver axis. Exosomes are essential carriers of intercellular communication. Most previous studies have focused on adipocyte- and hepatocyte-derived exosomes, while the critical role of microbial-derived exosomes and the molecular mechanisms behind them in MAFLD have received little attention. Therefore, we searched and screened the latest relevant studies in the PubMeb database to elucidate the link between microbial-derived exosomes and the pathogenesis of MAFLD, mainly in terms of insulin resistance, intestinal barrier, inflammatory response, lipid metabolism, and liver fibrosis. The aim was to provide a theoretical framework and support for clinical protocols and innovative drug development.

Inflammation and Nitro-oxidative Stress as Drivers of Endocannabinoid System Aberrations in Mood Disorders and Schizophrenia

The endocannabinoid system (ECS) is composed of the endocannabinoid ligands anandamide (AEA) and 2-arachidonoylgycerol (2-AG), their target cannabinoid receptors (CB₁ and CB₂) and the enzymes involved in their synthesis and metabolism (N-acyltransferase and fatty acid amide hydrolase (FAAH) in the case of AEA and diacylglycerol lipase (DAGL) and monoacylglycerol lipase (MAGL) in the case of 2-AG). The origins of ECS dysfunction in major neuropsychiatric disorders remain to be determined, and this paper explores the possibility that they may be associated with chronically increased nitro-oxidative stress and activated immune-inflammatory pathways, and it examines the mechanisms which might be involved. Inflammation and nitro-oxidative stress are associated with both increased CB₁ expression, via increased activity of the NADPH oxidases NOX4 and NOX1, and increased CNR1 expression and DNA methylation; and CB₂ upregulation via increased pro-inflammatory cytokine levels, binding of the transcription factor Nrf2 to an antioxidant response element in the CNR2 promoter region and the action of miR-139. CB₁ and CB₂ have antagonistic effects on redox signalling, which may result from a miRNA-enabled negative feedback loop. The effects of inflammation and oxidative stress are detailed in respect of AEA and 2-AG levels, via effects on calcium homeostasis and phospholipase A₂ activity; on FAAH activity, via nitrosylation/nitration of functional cysteine and/or tyrosine residues; and on 2-AG activity via effects on MGLL expression and MAGL. Finally, based on these detailed molecular neurobiological mechanisms, it is suggested that cannabidiol and dimethyl fumarate may have therapeutic potential for major depressive disorder, bipolar disorder and schizophrenia.

Combined Intestinal Metabolomics and Microbiota Analysis for Acute Endometritis Induced by Lipopolysaccharide in Mice

Endometritis is generally caused by bacterial infections, including both acute and chronic infections. In the past few decades, accumulated evidence showed that the occurrence of diseases might be related to gut microbiota. The progression of diseases is previously known to change the composition and diversity of intestinal microbiota. Additionally, it also causes corresponding changes in metabolites, primarily by affecting the physiological processes of microbiota. However, the effects of acute endometritis on intestinal microbiota and its metabolism remain unknown. Thus, the present study aimed to assess the effects of acute endometritis on intestinal microbes and their metabolites. Briefly, endometritis was induced in 30 specific pathogen-free (SPF) BALB/c female mice via intrauterine administration of lipopolysaccharide (LPS) after anesthesia. Following this, 16S rRNA gene sequencing and liquid chromatogram-mass spectrometry (LC-MS) were performed. At the genus level, the relative abundance of Klebsiella, Lachnoclostridium_5, and Citrobacter was found to be greater in the LPS group than in the control group. Importantly, the control group exhibited a higher ratio of Christensenellaceae_R−7_group and Parasutterella. Furthermore, intestinal metabolomics analysis in mice showed that acute endometritis altered the concentration of intestinal metabolites and affected biological oxidation, energy metabolism, and biosynthesis of primary bile acids. The correlation analysis between microbial diversity and metabolome provided a basis for a comprehensive understanding of the composition and function of the microbial community. Altogether, the findings of this study would be helpful in the prevention and treatment of acute endometritis in the future.

N-acetylcysteine alleviates high fat diet-induced hepatic steatosis and liver injury via regulating intestinal microecology in mice

N-acetylcysteine (NAC), a well-accepted antioxidant, has been shown to protect against high fat diet (HFD)-induced obesity-associated non-alcoholic fatty liver disease (NAFLD) in mice. However, the underlying mechanism(s) of the beneficial...

Formononetin reshapes the gut microbiota, prevents progression of obesity and improves host metabolism

Formononetin (FMNT) is an isoflavone that has been studied for its anti-hyperglycemic and anti-diabetic effects. However, the effect of FMNT on gut dysbiosis and metabolic complications associated with western-style diet consumption has not been reported yet. This study aimed to investigate how FMNT can reshape the gut microbiota at a specific dosage and ameliorate the symptoms of obesity-related metabolic disorders in both genders. Results indicate that FMNT at 60 mg per kg bodyweight dosage can effectively control body weight, hyperglycemia, and insulin resistance, leptin levels and improve HDL to LDL ratio. FMNT treatment suppressed Porphyromonadaceae (Uncultured Alistipes) and augmented maximum genera from families Lachnospiraceae and Clostridiacea, but at species level, formononetin increased Clostridium aldenense, Clostridiaceae unclassified, Eubacterium plexicaum; acetate and butyrate-producing bacteria. Moreover, formononetin regulated the expression of specific liver miRNA involved in obesity and down-regulated mRNA expression levels of pro-inflammatory cytokines IL-6, IL-22 and TNF-α. Additionally, FMNT maintained intestinal membrane integrity by regulating the expression of Muc-2 and occludin. Our findings indicate that FMNT could be a potential prebiotic that can effectively regulate the gut microbiota, improve host metabolism and systemic inflammation, and prevent deleterious effects of a western-style diet by elevating acetate lactate and lactate butyrate producers.

Milk replacer supplementation in early life optimizes the development of intestinal microbes in goats

Colonization and development of the gut microbiome during early life is important in establishing a host-microbial symbiotic relationship. It contributes to maintaining health and well-being throughout the life span. To date, early longitudinal development of intestinal microflora in the ileum micro-ecology of the Yimeng black goats (YBGs) is rare. The purpose of this research was to study the effect of milk replacer with age on the ileal microbiota growth and maturation in YBGs throughout the post-weaning phase. The newborn YBGs (n = 24) were divided into two groups, i.e., milk replacer (R group) and control group (B group). The microbiome of Ileum was observed on days 15, 25, 45, and 75. When compared with baseline (B group), the R group's alpha diversity was lower (day 15, 25, 45), but it gradually approached and exceeded the baseline in the later stages (day 75). On the time axis, the richness of intestinal microflora was increased with age, but there was no statistically significant difference. The relative abundances of Proteobacteria, Firmicutes, Peptoclustridium, Lachnospiraceae, and Prevotellaceae showed a continuous trend of increase initially. They then decreased except Ruminococcaceae, which reflected the gradual maturity of intestinal microbial development. Milk replacer treatment temporarily increased the abundance of Actinomycetes (day 25 and 45), while the relative proportion of several intestinal bacteria such as Parasutterella, Megasphaera, Prevotellaceae, Akkermansia, and Subdoligranulum species were significantly higher in R group than in B group. The major changes in gut microflora composition might reflect positive effect of milk replacer on the development and maturation of the intestine during the early stage, connecting with substrate availability in the gut. Our study provides an effective strategy to promote the development of the gut microbiome, which is helpful for a smooth transition during the early-weaning period in YBGs.

Crosstalk Between Polygonatum kingianum, the miRNA, and Gut Microbiota in the Regulation of Lipid Metabolism

Objectives: Polygonatum kingianum is a medicinal herb used in various traditional Chinese medicine formulations. The polysaccharide fraction of P. kingianum can reduce insulin resistance and restore the gut microbiota in a rat model of aberrant lipid metabolism by down regulating miR-122. The aim of this study was to further elucidate the effect of P. kingianum on lipid metabolism, and the roles of specific miRNAs and the gut microbiota. Key findings: P. kingianum administration significantly altered the abundance of 29 gut microbes and 27 differentially expressed miRNAs (DEMs). Several aberrantly expressed miRNAs closely related to lipid metabolism were identified, of which some were associated with specific gut microbiota. MiR-484 in particular was identified as the core factor involved in the therapeutic effects of P. kingianum. We hypothesize that the miR-484-Bacteroides/Roseburia axis acts as an important bridge hub that connects the entire miRNA-gut microbiota network. In addition, we observed that Parabacteroides and Bacillus correlated significantly with several miRNAs, including miR-484, miR-122-5p, miR-184 and miR-378b. Summary: P. kingianum alleviates lipid metabolism disorder by targeting the network of key miRNAs and the gut microbiota.

Impact of Genetic Polymorphism on Response to Therapy in Non-Alcoholic Fatty Liver Disease

In the last decades, the global prevalence of non-alcoholic fatty liver disease (NAFLD) has reached pandemic proportions with derived major health and socioeconomic consequences; this tendency is expected to be further aggravated in the coming years. Obesity, insulin resistance/type 2 diabetes mellitus, sedentary lifestyle, increased caloric intake and genetic predisposition constitute the main risk factors associated with the development and progression of the disease. Importantly, the interaction between the inherited genetic background and some unhealthy dietary patterns has been postulated to have an essential role in the pathogenesis of NAFLD. Weight loss through lifestyle modifications is considered the cornerstone of the treatment for NAFLD and the inter-individual variability in the response to some dietary approaches may be conditioned by the presence of different single nucleotide polymorphisms. In this review, we summarize the current evidence on the influence of the association between genetic susceptibility and dietary habits in NAFLD pathophysiology, as well as the role of gene polymorphism in the response to lifestyle interventions and the potential interaction between nutritional genomics and other emerging therapies for NAFLD, such as bariatric surgery and several pharmacologic agents.

Effect of Inonotus obliquus polysaccharide on composition of the intestinal flora in mice with acute endometritis

Inonotus obliquus Polysaccharide (IOP) is a large molecule extracted from Inonotus obliqus, a medicinal fungus, which has a wide range of biological activities and has been shown to be associated with inflammation. The purpose of this study is to investigate whether IOP can help to reduce acute endometritis by regulating intestinal flora. We observed pathological changes in mice with endometritis following treatment with IOP and evaluated changes in the levels of interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α), and further studied the effects of IOP on the intestinal flora of endometritis mice using 16S rRNA high-throughput sequencing. The results showed that IOP improved the condition of uterine tissues and reduced the release of pro-inflammatory cytokines. Meanwhile, the 16S rRNA sequencing results showed that IOP could regulate the changes in intestinal microflora at the level of genera, possibly by changing the relative abundance of some genera.

Molecular and Cellular Mediators of the Gut-Liver Axis in the Progression of Liver Diseases

The gut-liver axis covers the bidirectional communication between the gut and the liver, and thus includes signals from liver-to-gut (e.g., bile acids, immunoglobulins) and from gut-to-liver (e.g., nutrients, microbiota-derived products, and recirculating bile acids). In a healthy individual, liver homeostasis is tightly controlled by the mostly tolerogenic liver resident macrophages, the Kupffer cells, capturing the gut-derived antigens from the blood circulation. However, disturbances of the gut-liver axis have been associated to the progression of varying chronic liver diseases, such as non-alcoholic fatty liver disease, non-alcoholic steatohepatitis, and primary sclerosing cholangitis. Notably, changes of the gut microbiome, or intestinal dysbiosis, combined with increased intestinal permeability, leads to the translocation of gut-derived bacteria or their metabolites into the portal vein. In the context of concomitant or subsequent liver inflammation, the liver is then infiltrated by responsive immune cells (e.g., monocytes, neutrophils, lymphoid, or dendritic cells), and microbiota-derived products may provoke or exacerbate innate immune responses, hence perpetuating liver inflammation and fibrosis, and potentiating the risks of developing cirrhosis. Similarly, food derived antigens, bile acids, danger-, and pathogen-associated molecular patterns are able to reshape the liver immune microenvironment. Immune cell intracellular signaling components, such as inflammasome activation, toll-like receptor or nucleotide-binding oligomerization domain-like receptors signaling, are potent targets of interest for the modulation of the immune response. This review describes the current understanding of the cellular landscape and molecular pathways involved in the gut-liver axis and implicated in chronic liver disease progression. We also provide an overview of innovative therapeutic approaches and current clinical trials aiming at targeting the gut-liver axis for the treatment of patients with chronic liver and/or intestinal diseases.

Oral iron supplementation after antibiotic exposure induces a deleterious recovery of the gut microbiota

BACKGROUND

Oral iron supplementation is commonly prescribed for anemia and may play an important role in the gut microbiota recovery of anemic individuals who received antibiotic treatment. This study aims to investigate the effects of iron supplementation on gut microbiota recovery after antibiotics exposure.

RESULTS

Mice were subjected to oral antibiotic treatment with neomycin and metronidazole and were fed diets with different concentrations of iron. The composition of the gut microbiota was followed throughout treatment by 16S rRNA sequencing of DNA extracted from fecal samples. Gut microbiota functions were inferred using PICRUSt2, and short-chain fatty acid concentration in fecal samples was assessed by liquid-chromatography mass spectrometry. Iron supplementation after antibiotic exposure shifted the gut microbiota composition towards a Bacteroidetes phylum-dominant composition. At the genus level, the iron-supplemented diet induced an increase in the abundance of Parasutterella and Bacteroides, and a decrease of Bilophila and Akkermansia. Parasutterella excrementihominis, Bacteroides vulgatus, and Alistipes finegoldii, were more abundant with the iron excess diet. Iron-induced shifts in microbiota composition were accompanied by functional modifications, including an enhancement of the biosynthesis of primary bile acids, nitrogen metabolism, cyanoamino acid metabolism and pentose phosphate pathways. Recovery after antibiotic treatment increased propionate levels independent of luminal iron levels, whereas butyrate levels were diminished by excess iron.

CONCLUSIONS

Oral iron supplementation after antibiotic therapy in mice may lead to deleterious changes in the recovery of the gut microbiota. Our results have implications on the use of oral iron supplementation after antibiotic exposure and justify further studies on alternative treatments for anemia in these settings.

Cardiometabolic Syndrome: An Update on Available Mouse Models

Cardiometabolic syndrome (CMS), a disease entity characterized by abdominal obesity, insulin resistance (IR), hypertension, and hyperlipidemia, is a global epidemic with approximately 25% prevalence in adults globally. CMS is associated with increased risk for cardiovascular disease (CVD) and development of diabetes. Due to its multifactorial etiology, the development of several animal models to simulate CMS has contributed significantly to the elucidation of the disease pathophysiology and the design of therapies. In this review we aimed to present the most common mouse models used in the research of CMS. We found that CMS can be induced either by genetic manipulation, leading to dyslipidemia, lipodystrophy, obesity and IR, or obesity and hypertension, or by administration of specific diets and drugs. In the last decade, the ob/ob and db/db mice were the most common obesity and IR models, whereas Ldlr-/- and Apoe-/- were widely used to induce hyperlipidemia. These mice have been used either as a single transgenic or combined with a different background with or without diet treatment. High-fat diet with modifications is the preferred protocol, generally leading to increased body weight, hyperlipidemia, and IR. A plethora of genetically engineered mouse models, diets, drugs, or synthetic compounds that are available have advanced the understanding of CMS. However, each researcher should carefully select the most appropriate model and validate its consistency. It is important to consider the differences between strains of the same animal species, different animals, and most importantly differences to human when translating results.

Gut microbiome, parathyroid hormone, and bone

PURPOSE OF REVIEW

Microorganisms in the gut (the 'microbiome') and the metabolites they produce (the 'metabolome') regulate bone mass through interactions between parathyroid hormone (PTH), the immune system, and bone. This review summarizes these data and details how this physiology may relate to CKD-mediated bone disease.

RECENT FINDINGS

The actions of PTH on bone require microbial metabolite activation of immune cells. Butyrate is necessary for CD4+ T-cell differentiation, T-reg cell expansion and CD8+ T-cell secretion of the bone-forming factor Wnt10b ligand. By contrast, mice colonized with segmented filamentous bacteria exhibit an expansion of gut Th17 cells and continuous PTH infusion increases the migration of Th17 cells to the bone marrow, contributing to bone resorption. In the context of CKD, a modified diet, frequent antibiotic therapy, altered intestinal mobility, and exposure to multiple medications together contribute to dysbiosis; the implications for an altered microbiome and metabolome on the pathogenesis of renal osteodystrophy and its treatment have not been explored.

SUMMARY

As dysregulated interactions between PTH and bone ('skeletal resistance') characterize CKD, the time is ripe for detailed, mechanistic studies into the role that gut metabolites may play in the pathogenesis of CKD-mediated bone disease.

The Osteoporosis/Microbiota Linkage: The Role of miRNA

Hundreds of trillions of bacteria are present in the human body in a mutually beneficial symbiotic relationship with the host. A stable dynamic equilibrium exists in healthy individuals between the microbiota, host organism, and environment. Imbalances of the intestinal microbiota contribute to the determinism of various diseases. Recent research suggests that the microbiota is also involved in the regulation of the bone metabolism, and its alteration may induce osteoporosis. Due to modern molecular biotechnology, various mechanisms regulating the relationship between bone and microbiota are emerging. Understanding the role of microbiota imbalances in the development of osteoporosis is essential for the development of potential osteoporosis prevention and treatment strategies through microbiota targeting. A relevant complementary mechanism could be also constituted by the permanent relationships occurring between microbiota and microRNAs (miRNAs). miRNAs are a set of small non-coding RNAs able to regulate gene expression. In this review, we recapitulate the physiological and pathological meanings of the microbiota on osteoporosis onset by governing miRNA production. An improved comprehension of the relations between microbiota and miRNAs could furnish novel markers for the identification and monitoring of osteoporosis, and this appears to be an encouraging method for antagomir-guided tactics as therapeutic agents.

Correlations between α-Linolenic Acid-Improved Multitissue Homeostasis and Gut Microbiota in Mice Fed a High-Fat Diet

Previous studies have shown that α-linolenic acid (ALA) has a significant regulatory effect on related disorders induced by high-fat diets (HFDs), but little is known regarding the correlation between the gut microbiota and disease-related multitissue homeostasis. We systematically investigated the effects of ALA on the body composition, glucose homeostasis, hyperlipidemia, metabolic endotoxemia and systemic inflammation, white adipose tissue (WAT) homeostasis, liver homeostasis, intestinal homeostasis, and gut microbiota of mice fed an HFD (HFD mice). We found that ALA improved HFD-induced multitissue metabolic disorders and gut microbiota disorders to various degrees. Importantly, we established a complex but clear network between the gut microbiota and host parameters. Several specific differential bacteria were significantly associated with improved host parameters. Rikenellaceae_RC9_gut_group and Parasutterella were positively correlated with HFD-induced "harmful indicators" and negatively correlated with "beneficial indicators." Intriguingly, Bilophila showed a strong negative correlation with HFD-induced multitissue metabolic disorders and a significant positive correlation with most beneficial indicators, which is different from its previous characterization as a "potentially harmful genus." Turicibacter might be the key beneficial bacterium for ALA-improved metabolic endotoxemia, while Blautia might play an important role in ALA-improved gut barrier integrity and anti-inflammatory effects. The results suggested that the gut microbiota, especially some specific bacteria, played an important role in the process of ALA-improved multitissue homeostasis in HFD mice, and different bacteria might have different divisions of regulation.IMPORTANCE Insufficient intake of n-3 polyunsaturated fatty acids is an important issue in modern Western-style diets. A large amount of evidence now suggests that a balanced intestinal microecology is considered an important part of health. Our results show that α-linolenic acid administration significantly improved the host metabolic phenotype and gut microbiota of mice fed a high-fat diet, and there was a correlation between the improved gut microbiota and metabolic phenotype. Some specific bacteria may play a unique regulatory role. Here, we have established correlation networks between gut microbiota and multitissue homeostasis, which may provide a new basis for further elucidating the relationship between the gut microbiota and host metabolism.

Differences in Gut Microbiome Composition between Senior Orienteering Athletes and Community-Dwelling Older Adults

Background: Gastrointestinal (GI) health is an important aspect of general health. Gastrointestinal symptoms are of specific importance for the elderly, an increasing group globally. Hence, promoting the elderly’s health and especially gastrointestinal health is important. Gut microbiota can influence gastrointestinal health by modulation of the immune system and the gut–brain axis. Diverse gut microbiota have been shown to be beneficial; however, for the elderly, the gut microbiota is often less diverse. Nutrition and physical activity, in particular, are two components that have been suggested to influence composition or diversity. Materials and Methods: In this study, we compared gut microbiota between two groups of elderly individuals: community-dwelling older adults and physically active senior orienteering athletes, where the latter group has less gastrointestinal symptoms and a reported better well-being. With this approach, we explored if certain gut microbiota were related to healthy ageing. The participant data and faecal samples were collected from these two groups and the microbiota was whole-genome sequenced and taxonomically classified with MetaPhlAn. Results: The physically active senior orienteers had a more homogeneous microbiota within the group and a higher abundance of Faecalibacterium prausnitzii compared to the community-dwelling older adults. Faecalibacterium prausnitzii has previously shown to have beneficial properties. Senior orienteers also had a lower abundance of Parasutterella excrementihominis and Bilophila unclassified, which have been associated with impaired GI health. We could not observe any difference between the groups in terms of Shannon diversity index. Interestingly, a subgroup of community-dwelling older adults showed an atypical microbiota profile as well as the parameters for gastrointestinal symptoms and well-being closer to senior orienteers. Conclusions: Our results suggest specific composition characteristics of healthy microbiota in the elderly, and show that certain components of nutrition as well as psychological distress are not as tightly connected with composition or diversity variation in faecal microbiota samples.

Gender-associated differences in oral microbiota and salivary biochemical parameters in response to feeding

Saliva plays a key role in food absorption and digestion mainly due to both its enzymes and microbiota. The main objective of this study was to compare the oral microbiota and salivary parameters between men and women in response to feeding. To answer this question, we set up a pilot study on 10 male and 10 female subjects to examine the role of saliva in glycaemia physiology. Biological parameters and the microbiotal composition of saliva were analyzed in fasted and fed states. The results show that the level of blood glucose was not different between men and women in the fasted state (88.00 mg/dL ± 6.38 vs 87.00 mg/dL ±8.07, p = 0.9149) or in the fed state (102.44 mg/dL ± 14.03 vs 116.9 mg/dL ± 25, p = 0.1362). Free fatty acids (FFA 0.15 mmol/L ± 0.15 vs 0.07 mmol/L ± 0.07, p = 0,0078), cholesterol (0.53 mmol/L ± 0.30 vs 0.15 mmol/L ± 0.14, p < 0.0001), and total saliva proteins (13.2 g/L ± 4.31 vs 9.02 g/L ± 6.98, p = 0.0168) were decreased after feeding, as well as the saliva lipase (27.89 U/L ± 25.7 vs 12.28 U/L ± 4.85, p = 0.0126). A very significant increase in the relative abundance of Streptococcaceae (24.56 ± 9.32 vs 13.53 ± 7.47, p = 0.00055) and a decrease in Prevotellaceae (34.45 ± 9.30 vs 17.43 ± 9.03, p = 0.00055) were observed in the fed condition. When investigating gender-related differences in the fasted state, men showed higher levels of cholesterol (0.71 mmol/L ± 0.26 vs 0.40 mmol/L ± 0.27, p = 0.0329), FFA (0.25 mmol/L ± 0.18 vs 0.08 mmol/L ± 0.06, p = 0.0049), and triglycerides (0.24 mmol/L ± 0.15 vs 0.09 mmol/L ± 0.04, p = 0.006) than women. Finally, differences could be observed in saliva microbiota between men and women in the fasted condition but even more in the fed condition, where Porphyromonas and Capnocytophaga were overrepresented in the male salivary samples compared with female saliva. Thus, biological parameters and microbiota in saliva could be the signatures of the feeding conditions and sex gender status.

Interactions between the MicroRNAs and Microbiota in Cancer Development: Roles and Therapeutic Opportunities

The human microbiota is made up of the fungi, bacteria, protozoa and viruses cohabiting within the human body. An altered microbiota can provoke diseases such as cancer. The mechanisms by which a modified microbiota can intervene in the onset and progression of neoplastic diseases are manifold. For instance, these include the effects on the immune system and the onset of obesity. A different mechanism seems to be constituted by the continuous and bidirectional relationships existing between microbiota and miRNAs. MiRNAs emerged as a novel group of small endogenous non-coding RNAs from that control gene expression. Several works seem to confirm the presence of a close connection between microbiota and miRNAs. Although the main literature data concern the correlations between microbiota, miRNAs and colon cancer, several researches have revealed the presence of connections with other types of tumour, including the ovarian tumour, cervical carcinoma, hepatic carcinoma, neoplastic pathologies of the central nervous system and the possible implication of the microbiota-miRNAs system on the response to the treatment of neoplastic pathologies. In this review, we summarise the physiological and pathological functions of the microbiota on cancer onset by governing miRNA production. A better knowledge of the bidirectional relationships existing between microbiota and miRNAs could provide new markers for the diagnosis, staging and monitoring of cancer and seems to be a promising approach for antagomir-guided approaches as therapeutic agents.

Sexual Dimorphism of Gut Microbiota Dictates Therapeutics Efficacy of Radiation Injuries

Accidental or iatrogenic ionizing radiation exposure precipitates acute and chronic radiation injuries. The traditional paradigm of mitigating radiotherapy-associated adverse side effects has ignored the gender-specific dimorphism of patients' divergent responses. Here, the effects of sexual dimorphism on curative efficiencies of therapeutic agents is examined in murine models of irradiation injury. Oral gavage of simvastatin ameliorates radiation-induced hematopoietic injury and gastrointestinal tract dysfunction in male mice, but adversely deteriorates these radiation syndromes in female animals. In a sharp contrast, feeding animals with high-fat diet (HFD) elicites explicitly contrary results. High-throughput sequencing of microbial 16S rRNA, host miRNA, and mRNA shows that simvastatin or HFD administration preventes radiation-altered enteric bacterial taxonomic structure, preserves miRNA expression profile, and reprogrammes the spectrum of mRNA expression in small intestines of male or female mice, respectively. Notably, faecal microbiota transplantation of gut microbes from opposite sexual donors abrogates the curative effects of simvastatin or HFD in respective genders of animals. Together, these findings demonstrate that curative efficiencies of therapeutic strategies mitigating radiation toxicity might be dependent on the gender of patients, thus simvastatin or HFD might be specifically useful for fighting against radiation toxicity in a sex-dependent fashion partly based on sex-distinct gut microbiota composition in preclinical settings.

Gnotobiotic mice inoculated with Firmicutes, but not Bacteroidetes, deteriorate nonalcoholic fatty liver disease severity by modulating hepatic lipid metabolism

Nonalcoholic fatty liver disease (NAFLD) is a serious liver disorder and characterized by the hepatic accumulation of excess fatty acids. Clinical studies and animal models have shown a shift of gut microbiota from bacteroidetes to firmicutes in NAFLD patients and a diet-induced NAFLD mouse model. Therefore, we hypothesized that these 2 groups of bacteria may have differential effects on lipid metabolism in the liver, which further contributed to pathogenesis of NAFLD. To elucidate these effects, we inoculated two species of Bacteroidetes (B-group) or five species of Firmicutes (F-group) which were isolated from healthy individuals into germ-free mice. We found that the F-group induced elevated body weight, liver weight, and hepatic steatosis compared to the B-group under high-fat diet (HFD) conditions. The mRNA expression level of cluster of differentiation 36 (CD36) was elevated in the F-group compared to that in the B-group. Increased mRNA expression levels of fatty acid synthase (FAS), stearoyl-CoA desaturase-1 (SCD1), and diacylglycerol O-acyltransferase 2 (DGAT2) were also seen under HFD conditions in the F-group compared to that in the B-group. In addition, the expression level of miR802-5p was only elevated in the F-group under HFD conditions. Taken together, our results suggested that these specific species of Firmicutes may induce more hepatic steatosis by modulating fatty acid influx and lipogenesis compared to those of Bacteroidetes. These results may provide more understanding of the effects of gut microbiota on NAFLD.

Unaccounted risk of cardiovascular disease: the role of the microbiome in lipid metabolism

PURPOSE OF REVIEW

Not all of the risk of cardiovascular disease can be explained by diet and genetics, and the human microbiome, which lies at the interface of these two factors, may help explain some of the unaccounted risk. This review examines some of the well established links between the microbiome and cardiovascular health, and proposes relatively unexplored associations.

RECENT FINDINGS

Byproducts of microbial metabolism are associated with health and disease: Trimethylamine N oxide is associated with atherosclerosis; whereas short-chain fatty acids are associated with decreased inflammation and increased energy expenditure. More broadly, a large number of association studies have been conducted to explore the connections between bacterial taxa and metabolic syndrome. In contrast, the relationship between the microbiome and triglycerides levels remains poorly understood.

SUMMARY

We suggest that deeper understanding of the molecular mechanisms that drive linkages between the microbiome and disease can be determined by replacing 16S rRNA gene sequencing with shotgun metagenomic sequencing or other functional approaches. Furthermore, to ensure translatability and reproducibility of research findings, a combination of multiple different complementary '-omic' approaches should be employed.

Defining the role of Parasutterella, a previously uncharacterized member of the core gut microbiota

The genus of Parasutterella has been defined as a core component of the human and mouse gut microbiota, and has been correlated with various health outcomes. However, like most core microbes in the gastrointestinal tract (GIT), very little is known about the biology of Parasutterella and its role in intestinal ecology. In this study, Parasutterella was isolated from the mouse GIT and characterized in vitro and in vivo. Mouse, rat, and human Parasutterella isolates were all asaccharolytic and producers of succinate. The murine isolate stably colonized the mouse GIT without shifting bacterial composition. Notable changes in microbial-derived metabolites were aromatic amino acid, bilirubin, purine, and bile acid derivatives. The impacted bile acid profile was consistent with altered expression of ileal bile acid transporter genes and hepatic bile acid synthesis genes, supporting the potential role of Parasutterella in bile acid maintenance and cholesterol metabolism. The successful colonization of Parasutterella with a single environmental exposure to conventional adult mice demonstrates that it fills the ecological niche in the GIT and contributes to metabolic functionalities. This experiment provides the first indication of the role of Parasutterella in the GIT, beyond correlation, and provides insight into how it may contribute to host health.

Dietary wood pulp-derived sterols modulation of cholesterol metabolism and gut microbiota in high-fat-diet-fed hamsters

Wood pulp-derived sterols (WS) supplementation ameliorated HFD-associated metabolic disorder; WS supplementation increased the amounts of fecal sterols excretion and SCFAs content; WS supplementation modulated gut microbiota composition.

miRNA Signature in NAFLD: A Turning Point for a Non-Invasive Diagnosis

Nonalcoholic fatty liver disease (NAFLD) defines a wide pathological spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) which may predispose to liver cirrhosis and hepatocellular carcinoma. It represents the leading cause of hepatic damage worldwide. Diagnosis of NASH still requires liver biopsy but due to the high prevalence of NAFLD, this procedure, which is invasive, is not practicable for mass screening. Thus, it is crucial to non-invasively identify NAFLD patients at higher risk of progression to NASH and fibrosis. It has been demonstrated that hepatic fat content and progressive liver damage have a strong heritable component. Therefore, genetic variants associated with NAFLD have been proposed as non-invasive markers to be used in clinical practice. However, genetic variability is not completely explained by these common variants and it is possible that many of the phenotypic differences result from gene-environment interactions. Indeed, NAFLD development and progression is also modulated by epigenetic factors, in particular microRNAs (miRNAs), which control at post-transcriptional level many complementary target mRNAs and whose dysregulation has been shown to have high prognostic and predictive value in NAFLD. The premise of the current review is to discuss the role of miRNAs as pathogenic factors, risk predictors and therapeutic targets in NAFLD.

High-fat diet overfeeding promotes nondetrimental liver steatosis in female mice

High-fat diet (HFD) feeding or leptin-deficient mice are extensively used as models resembling features of human nonalcoholic fatty liver disease (NAFLD). The concurrence of experimental factors as fat content and source or total caloric intake leads to prominent differences in the development of the hepatic steatosis and related disturbances. In this work, we characterized the hepatic lipid accumulation induced by HFD in wild-type (WT) and ob/ ob mice with the purpose of differentiating adaptations to HFD from those specific of increased overfeeding due to leptin deficiency-associated hyperphagia. Given that most published works have been done in male models, we used female mice with the aim of increasing the body of evidence regarding NAFLD in female subjects. HFD promoted liver lipid accumulation only in the hyperphagic strain. Nevertheless, a decrease of lipid droplet-associated cholesteryl ester (CE) in both WT and obese animals was observed. These changes were accompanied by an improvement in the profile of lipoproteins that transport cholesterol and liver function markers in plasma from ob/ ob mice and a lower hepatic index. Using primary hepatocytes from female mice, overaccumulation of CE induced by 0.4 mM oleic acid reversed in the presence of a specific Takeda G protein-coupled bile acid receptor agonist. Nevertheless, hepatocytes from male mice were not responsive. This study suggests that enterohepatic circulation of bile acids might be one of the factors that can affect sex dimorphism in NAFLD development, which underlines the importance of including female models in the NAFLD research field. NEW & NOTEWORTHY This work provides new insight into the use of high-fat diet as a model to induce nonalcoholic fatty liver disease in wild-type and ob/ ob female mice. We show that high-fat diet induces steatosis only in ob/ ob mice while, surprisingly, several health indicators improve. Noteworthy, experiments with primary hepatocytes from male and female mice show that they express Takeda G protein-coupled bile acid receptor and that it and bile acid enterohepatic circulation might be accountable for sex dimorphism in nonalcoholic fatty liver disease development.

Dietary Exposure to the Environmental Chemical, PFOS on the Diversity of Gut Microbiota, Associated With the Development of Metabolic Syndrome

The gut microbiome is a dynamic ecosystem formed by thousands of diverse bacterial species. This bacterial diversity is acquired early in life and shaped over time by a combination of multiple factors, including dietary exposure to distinct nutrients and xenobiotics. Alterations of the gut microbiota composition and associated metabolic activities in the gut are linked to various immune and metabolic diseases. The microbiota could potentially interact with xenobiotics in the gut environment as a result of their board enzymatic capacities and thereby affect the bioavailability and toxicity of the xenobiotics in enterohepatic circulation. Consequently, microbiome-xenobiotic interactions might affect host health. Here, we aimed to investigate the effects of dietary perfluorooctane sulfonic acid (PFOS) exposure on gut microbiota in adult mice and examine the induced changes in animal metabolic functions. In mice exposed to dietary PFOS for 7 weeks, body PFOS and lipid contents were measured, and to elucidate the effects of PFOS exposure, the metabolic functions of the animals were assessed using oral glucose-tolerance test and intraperitoneal insulin-tolerance and pyruvate-tolerance tests; moreover, on Day 50, cecal bacterial DNA was isolated and subject to 16S rDNA sequencing. Our results demonstrated that PFOS exposure caused metabolic disturbances in the animals, particularly in lipid and glucose metabolism, but did not substantially affect the diversity of gut bacterial species. However, marked modulations were detected in the abundance of metabolism-associated bacteria belonging to the phyla Firmicutes, Bacteroidetes, Proteobacteria, and Cyanobacteria, including, at different taxonomic levels, Turicibacteraceae, Turicibacterales, Turicibacter, Dehalobacteriaceae, Dehalobacterium, Allobaculum, Bacteroides acidifaciens, Alphaproteobacteria, and 4Cod-2/YS2. The results of PICRUSt analysis further indicated that PFOS exposure perturbed gut metabolism, inducing notable changes in the metabolism of amino acids (arginine, proline, lysine), methane, and a short-chain fatty acid (butanoate), all of which are metabolites widely recognized to be associated with inflammation and metabolic functions. Collectively, our study findings provide key information regarding the biological relevance of microbiome-xenobiotic interactions associated with the ecology of gut microbiota and animal energy metabolism.

Molecular Paths Linking Metabolic Diseases, Gut Microbiota Dysbiosis and Enterobacteria Infections

Alterations of both ecology and functions of gut microbiota are conspicuous traits of several inflammatory pathologies, notably metabolic diseases such as obesity and type 2 diabetes. Moreover, the proliferation of enterobacteria, subdominant members of the intestinal microbial ecosystem, has been shown to be favored by Western diet, the strongest inducer of both metabolic diseases and gut microbiota dysbiosis. The inner interdependence between the host and the gut microbiota is based on a plethora of molecular mechanisms by which host and intestinal microbes modify each other. Among these mechanisms are as follows: (i) the well-known metabolic impact of short chain fatty acids, produced by microbial fermentation of complex carbohydrates from plants; (ii) a mutual modulation of miRNAs expression, both on the eukaryotic (host) and prokaryotic (gut microbes) side; (iii) the production by enterobacteria of virulence factors such as the genotoxin colibactin, shown to alter the integrity of host genome and induce a senescence-like phenotype in vitro; (iv) the microbial excretion of outer-membrane vesicles, which, in addition to other functions, may act as a carrier for multiple molecules such as toxins to be delivered to target cells. In this review, I describe the major molecular mechanisms by which gut microbes exert their metabolic impact at a multi-organ level (the gut barrier being in the front line) and support the emerging triad of metabolic diseases, gut microbiota dysbiosis and enterobacteria infections.

Effects of microencapsulated Lactobacillus plantarum LIP-1 on the gut microbiota of hyperlipidaemic rats

The in vivo effects of administering free and microencapsulated Lactobacillus plantarum LIP-1 cells (2·0×109 colony-forming units/d) were evaluated in high-fat-diet-induced hyperlipidaemic rats. Results from real-time quantitative PCR targeting to LIP-1 cells showed a higher colon colonisation count of LIP-1 in the rats receiving microencapsulated cells compared with free cells (P<0·05). Moreover, the microencapsulated LIP-1 treatment resulted in a more obvious lipid-lowering effect (P<0·05). Meanwhile, their faecal samples had significantly less lipopolysaccharide-producing bacteria (especially Bilophila, Sutterella and Oscillibacter) and mucosa-damaging bacteria (Bilophila and Akkermansia muciniphila), whereas significantly more SCFA-producing bacteria (P<0·05) (namely Lactobacillus, Alloprevotella, Coprococcus, Eubacterium and Ruminococcus) and bacteria that potentially possessed bile salt hydrolase activity (Bacteroides, Clostridium, Eubacterium and Lactobacillus), and other beneficial bacteria (Alistipes and Turicibacter). Further, Spearman's correlation analysis showed significant correlations between some of the modulated gut bacteria and the serum lipid levels. These results together confirm that microcapsulation enhanced the colon colonisation of LIP-1 cells, which subsequently exhibited more pronounced effects in improving the gut microbiota composition of hyperlipidaemic rats and lipid reduction.

Chondroitin sulfate disaccharides modified the structure and function of the murine gut microbiome under healthy and stressed conditions

Chondroitin sulfate (CS) has been widely used for medical and nutraceutical purposes due to its roles in maintaining tissue structural integrity. We investigated if CS disaccharides may act as a bioactive compound and modulate gut microbial composition in mice. Our data show that CS disaccharides supplementation for 16 days significantly reduced blood LPS in the mice experiencing exhaustive exercise stress. CS disaccharides partially restored total fecal short-chain fatty acids from the level significantly repressed in mice under the stress. Our findings demonstrated that CS was likely butyrogenic and resulted in a significant increase in fecal butyrate concentration. CS disaccharides had a profound impact on gut microbial composition, affecting the abundance of 13.6% and 7.3% Operational Taxonomic Units in fecal microbial communities in healthy and stressed mice, respectively. CS disaccharides reduced the prevalence of inflammatory Proteobacteria. Together, our findings demonstrated that CS may ameliorate stress-induced intestinal inflammation. Furthermore, CS significantly increased intestinal Bacteroides acidifaciens population, indirectly exerting its immunomodulatory effect on the intestine. CS disaccharides had a significant impact on a broad range of biological pathways under stressed condition, such as ABC transporters, two-component systems, and carbohydrate metabolism. Our results will facilitate the development of CS as a bioactive nutraceutical.

Transfer of dysbiotic gut microbiota has beneficial effects on host liver metabolism

Gut microbiota dysbiosis has been implicated in a variety of systemic disorders, notably metabolic diseases including obesity and impaired liver function, but the underlying mechanisms are uncertain. To investigate this question, we transferred caecal microbiota from either obese or lean mice to antibiotic-free, conventional wild-type mice. We found that transferring obese-mouse gut microbiota to mice on normal chow (NC) acutely reduces markers of hepatic gluconeogenesis with decreased hepatic PEPCK activity, compared to non-inoculated mice, a phenotypic trait blunted in conventional NOD2 KO mice. Furthermore, transferring of obese-mouse microbiota changes both the gut microbiota and the microbiome of recipient mice. We also found that transferring obese gut microbiota to NC-fed mice then fed with a high-fat diet (HFD) acutely impacts hepatic metabolism and prevents HFD-increased hepatic gluconeogenesis compared to non-inoculated mice. Moreover, the recipient mice exhibit reduced hepatic PEPCK and G6Pase activity, fed glycaemia and adiposity. Conversely, transfer of lean-mouse microbiota does not affect markers of hepatic gluconeogenesis. Our findings provide a new perspective on gut microbiota dysbiosis, potentially useful to better understand the aetiology of metabolic diseases.