Lactobacillus acidophilus NCFM affects vitamin E acetate metabolism and intestinal bile acid signature in monocolonized mice

Multi-omics analysis reveals leucine deprivation promotes bile acid synthesis by upregulating hepatic CYP7A1 and intestinal Turicibacter sanguinis in mice

BACKGROUND

Leucine, a branched-chain amino acid (BCAA), participates in the regulation of lipid metabolism and the composition of the intestinal microbiota. However, the related mechanism remains unclear.

OBJECTIVES

Here, we aimed to reveal the potential mechanisms by which the hepatic CYP7A1 (a rate-limiting enzyme for bile acid [BA] synthesis) and gut microbiota co-regulated BA synthesis under leucine deprivation.

METHODS

To this aim, 8-week-old C57BL/6J mice were fed with either regular diets or leucine-free diets for 1 week. Then, we investigated whether secondary BAs were synthesized by Turicibacter sanguinis in 7-week-old C57BL/6J germ-free mice gavaged with T.sanguinis for 2 weeks by determining BA concentrations in the plasma, liver, and cecum contents using liquid chromatography-tandem mass spectrometry.

RESULTS

The results showed that leucine deprivation resulted in a significant increase in total BA concentration in the plasma and an increase in the liver, but no difference in total BA was observed in the cecum contents before and after leucine deprivation. Furthermore, leucine deprivation significantly altered BA profiles such as taurocholic acid and omega-muricholic acid in the plasma, liver, and cecum contents. The expression of CYP7A1 was significantly upregulated in the liver under leucine deprivation. Leucine deprivation also regulated the composition of the gut microbiota, especially it significantly up-regulated the relative abundance of T.sanguinis, thus enhancing the conversion of primary BAs into secondary BAs by intestinal T.sanguinis in mice.

CONCLUSIONS

Overall, leucine deprivation regulated BA profiles in enterohepatic circulation by upregulating hepatic CYP7A1 expression and increasing intestinal T.sanguinis abundance. Our findings reveal the contribution of gut microbiota to BA metabolism under dietary leucine deprivation.

Immunological aspects of probiotics for improving skin diseases: Influence on the Gut-Brain-Skin Axis

The interplay between gut microbiota and human health, both mental and physical, is well-documented. This connection extends to the gut-brain-skin axis, linking gut microbiota to skin health. Recent studies have underscored the potential of probiotics and prebiotics to modulate gut microbiota, supported by in vivo and clinical investigations. In this comprehensive review, we explore the immunological implications of probiotics in influencing the gut-skin axis for the treatment and prevention of skin conditions, including psoriasis, acne, diabetic ulcers, atopic dermatitis, and skin cancer. Our analysis reveals that probiotics exert their effects by modulating cytokine production, whether administered orally or topically. Probiotics bolster skin defenses through the production of antimicrobial peptides and the induction of keratinocyte differentiation and regeneration. Yet, many questions surrounding probiotics remain unanswered, necessitating further exploration of their mechanisms of action in the context of skin diseases.

Vitamins as regulators of calcium-containing kidney stones - new perspectives on the role of the gut microbiome

Calcium-based kidney stone disease is a highly prevalent and morbid condition, with an often complicated and multifactorial aetiology. An abundance of research on the role of specific vitamins (B6, C and D) in stone formation exists, but no consensus has been reached on how these vitamins influence stone disease. As a consequence of emerging research on the role of the gut microbiota in urolithiasis, previous notions on the contribution of these vitamins to urolithiasis are being reconsidered in the field, and investigation into previously overlooked vitamins (A, E and K) was expanded. Understanding how the microbiota influences host vitamin regulation could help to determine the role of vitamins in stone disease.

The Potential Value of Probiotics after Dental Implant Placement

Dental implantation is currently the optimal solution for tooth loss. However, the health and stability of dental implants have emerged as global public health concerns. Dental implant placement, healing of the surgical site, osseointegration, stability of bone tissues, and prevention of peri-implant diseases are challenges faced in achieving the long-term health and stability of implants. These have been ongoing concerns in the field of oral implantation. Probiotics, as beneficial microorganisms, play a significant role in the body by inhibiting pathogens, promoting bone tissue homeostasis, and facilitating tissue regeneration, modulating immune-inflammatory levels. This review explores the potential of probiotics in addressing post-implantation challenges. We summarize the existing research regarding the importance of probiotics in managing dental implant health and advocate for further research into their potential applications.

Different Effects of Different Lactobacillus acidophilus Strains on DSS-Induced Colitis

Inflammatory bowel disease (IBD) is a worldwide chronic intestinal inflammatory immune-related disease. In this study, mice with dextran sulfate sodium (DSS)-induced colitis were used to evaluate the effect of Lactobacillus acidophilus on colitis. The results revealed that L. acidophilus CCFM137 and FAHWH11L56 show potential for relieving colitis symptoms, while L. acidophilus FGSYC48L79 did not show a protective effect. Moreover, L. acidophilus NCFM and FAHWH11L56 showed similar effects on various indicators of DSS-induced colitis, increasing the IL-10 and IL-17 in the colon, and modifying the CCL2/CCR2 axis and CCL3/CCR1 axis. For L. acidophilus CCFM137, its effects on colitis were different from the above two strains. Moreover, L. acidophilus FGSYC48L79 had negative effects on colitis by increasing the abundance of harmful bacteria in the gut microbiota and may promote the signaling of chemokines and their receptors. This may be related to its special genome compared to the other strains.

Dietary nutrients mediate crosstalk between bile acids and gut microbes in animal host metabolism

Bile acids (BAs) are synthesized by liver, then gut microbes embellish primary BAs into secondary BAs with diverse and biological functions. Over the past few decades, amounts of evidences demonstrated the importance of gut microbes in BA metabolism. There is also significant evidence that BAs are regarded as cell signals in gut-liver, gut-brain, and gut-testis axis. Moreover, the interaction between BAs and gut microbes plays a key role not only in the absorption and metabolism of nutrients, but the regulation of immune function. Herein, we collected the major information of the BA metabolism-related bacteria, nutrients, and cell signals, focused on the possible molecular mechanisms by "Microbes-Bile acids" crosstalk, highlighted the gut-liver, gut-brain, and gut-testis axis, and discussed the possibility and application of the regulation of BA metabolism by nutrients.

Dietary vitamin E reaches the mitochondria in the flight muscle of zebra finches but only if they exercise

Whether dietary antioxidants are effective for alleviating oxidative costs associated with energy-demanding life events first requires they are successfully absorbed in the digestive tract and transported to sites associated with reactive species production (e.g. the mitochondria). Flying birds are under high energy and oxidative demands, and although birds commonly ingest dietary antioxidants in the wild, the bioavailability of these consumed antioxidants is poorly understood. We show for the first time that an ingested lipophilic antioxidant, α-tocopherol, reached the mitochondria in the flight muscles of a songbird but only if they regularly exercise (60 min of perch-to-perch flights two times in a day or 8.5 km day-1). Deuterated α-tocopherol was found in the blood of exercise-trained zebra finches within 6.5 hrs and in isolated mitochondria from pectoral muscle within 22.5 hrs, but never reached the mitochondria in caged sedentary control birds. This rapid pace (within a day) and extent of metabolic routing of a dietary antioxidant to muscle mitochondria means that daily consumption of such dietary sources can help to pay the inevitable oxidative costs of flight muscle metabolism, but only when combined with regular exercise.

Weak Microbial Metabolites: a Treasure Trove for Using Biomimicry to Discover and Optimize Drugs

For decades, traditional drug discovery has used natural product and synthetic chemistry approaches to generate libraries of compounds, with some ending as promising drug candidates. A complementary approach has been to adopt the concept of biomimicry of natural products and metabolites so as to improve multiple drug-like features of the parent molecule. In this effort, promiscuous and weak interactions between ligands and receptors are often ignored in a drug discovery process. In this Emerging Concepts article, we highlight microbial metabolite mimicry, whereby parent metabolites have weak interactions with their receptors that then have led to discrete examples of more potent and effective drug-like molecules. We show specific examples of parent-metabolite mimics with potent effects in vitro and in vivo. Furthermore, we show examples of emerging microbial ligand-receptor interactions and provide a context in which these ligands could be improved as potential drugs. A balanced conceptual advance is provided in which we also acknowledge potential pitfalls-hyperstimulation of finely balanced receptor-ligand interactions could also be detrimental. However, with balance, we provide examples of where this emerging concept needs to be tested. SIGNIFICANCE STATEMENT: Microbial metabolite mimicry is a novel way to expand on the chemical repertoire of future drugs. The emerging concept is now explained using specific examples of the discovery of therapeutic leads from microbial metabolites.

Effects of antibiotics on degradation and bioavailability of different vitamin E forms in mice

Tocopherols (T) and tocotrienols (T3), all existing in α, β, γ, and δ-forms, are the eight forms of vitamin E (VE). In this study, we investigated the effects of gut microbiota on the degradation and tissue levels of different VE forms by treating mice with antibiotics in drinking water for 12 days. The mice also received an intragastric (i.g.) dose of VE mixture (mVE; α-T, γ-T, δ-T, γ-T3, and δ-T3, each at a dose of 75 mg/kg) every morning. Antibiotic treatment significantly increased the blood levels of all VE forms in mice that received an i.g. dose of mVE in the morning, 3 h before sacrifice. Without this morning dose, the blood levels of α-T were at the normal physiological levels, but those of the other VE forms were much lower; and the levels of all VE forms were not significantly affected by antibiotics. The liver levels of these VE forms were generally higher and followed the same pattern as the serum. On the contrary, the levels of most side-chain degradation metabolites of VE forms in the serum, liver, kidney, urine, and fecal samples were significantly decreased by antibiotics. The increased bioavailability of VE by antibiotics is probably due to increased absorption of VE or its decreased degradation by gut microbes. The results demonstrate the important roles of gut microbiota in the degradation of VE and in decreasing the bioavailabilities of VE forms. © 2019 BioFactors, 45(3):450-462, 2019.

Comparison of the microbiome, metabolome, and lipidome of obese and non-obese horses

Metabolic diseases such as obesity and type 2 diabetes in humans have been linked to alterations in the gastrointestinal microbiota and metabolome. Knowledge of these associations has improved our understanding of the pathophysiology of these diseases and guided development of diagnostic biomarkers and therapeutic interventions. The cellular and molecular pathophysiology of equine metabolic syndrome (EMS) and obesity in horses, however, remain ill-defined. Thus, the objectives of this study were to characterize the fecal microbiome, fecal metabolome, and circulating lipidome in obese and non-obese horses. The fecal microbiota, fecal metabolome, and serum lipidome were evaluated in obese (case) horses (n = 20) and non-obese (control) horses (n = 20) matched by farm of origin (n = 7). Significant differences in metabolites of the mitochondrial tricarboxylic acid cycle and circulating free fatty acids were identified in the obese horses compared to the non-obese horses. These results indicate that the host and bacterial metabolism should be considered important in obese horses. Further studies to determine whether these associations are causal and the mechanistic basis of the association are warranted because they might reveal diagnostic biomarkers and therapeutic interventions to mitigate obesity, EMS, and sequelae including laminitis.

Metabolomics and Lipidomics Approaches in the Science of Probiotics: A Review

The intestinal microflora plays important roles in the health of the host, such as nutrient processing and the modulation of intestinal immune responses. The constituents of the diet greatly affect the composition of the microbiota and its metabolites. The human intestinal microbiota is made up of around 100 trillion microbial cells encompassing at least 300 species. Consuming probiotics may lead to changes in the intestinal microflora that influence host health. Metabolomics is a powerful tool for revealing metabolic changes in biofluids, tissues, and organs of hosts induced by the consumption of probiotics, and lipidomics in particular is a technical approach that focuses on the analysis of lipids in various cells and biofluids. Metabolomics and lipidomics have been used to investigate intracellular and extracellular metabolites as well as for the nontargeted profiling and fingerprinting of metabolites. Based on metabolomics and lipidomics investigations, we reviewed the effects of consuming probiotics on metabolic profiles in controlled intestinal environments. We also discuss the associations between metabolic changes and human diseases after consuming probiotics in uncontrolled intestinal environments. In addition, we review the metabolic changes that take place within the food matrix during probiotic fermentation.

Probiotics or pro-healers: the role of beneficial bacteria in tissue repair

Probiotics are beneficial microorganisms, known to exert numerous positive effects on human health, primarily in the battle against pathogens. Probiotics have been associated with improved healing of intestinal ulcers, and healing of infected cutaneous wounds. This article reviews the latest findings on probiotics related to their pro-healing properties on gut epithelium and skin. Proven mechanisms by which probiotic bacteria exert their beneficial effects include direct killing of pathogens, competitive displacement of pathogenic bacteria, reinforcement of epithelial barrier, induction of fibroblasts, and epithelial cells' migration and function. Beneficial immunomodulatory effects of probiotics relate to modulation and activation of intraepithelial lymphocytes, natural killer cells, and macrophages through induced production of cytokines. Systemic effects of beneficial bacteria and link between gut microbiota, immune system, and cutaneous health through gut-brain-skin axes are discussed as well. In light of growing antibiotic resistance of pathogens, antibiotic use is becoming less effective in treating cutaneous and systemic infections. This review points to a new perspective and therapeutic potential of beneficial probiotic species as a safe alternative approach for treatment of patients affected by wound healing disorders and cutaneous infections.

Exploring the human microbiome from multiple perspectives: factors altering its composition and function

Our microbiota presents peculiarities and characteristics that may be altered by multiple factors. The degree and consequences of these alterations depend on the nature, strength and duration of the perturbations as well as the structure and stability of each microbiota. The aim of this review is to sketch a very broad picture of the factors commonly influencing different body sites, and which have been associated with alterations in the human microbiota in terms of composition and function. To do so, first, a graphical representation of bacterial, fungal and archaeal genera reveals possible associations among genera affected by different factors. Then, the revision of sequence-based predictions provides associations with functions that become part of the active metabolism. Finally, examination of microbial metabolite contents and fluxes reveals whether metabolic alterations are a reflection of the differences observed at the level of population structure, and in the last step, link microorganisms to functions under perturbations that differ in nature and aetiology. The utilisation of complementary technologies and methods, with a special focus on metabolomics research, is thoroughly discussed to obtain a global picture of microbiota composition and microbiome function and to convey the urgent need for the standardisation of protocols.

Multi-Omics Reveals that Lead Exposure Disturbs Gut Microbiome Development, Key Metabolites, and Metabolic Pathways

Lead exposure remains a global public health issue, and the recent Flint water crisis has renewed public concern about lead toxicity. The toxicity of lead has been well established in a variety of systems and organs. The gut microbiome has been shown to be highly involved in many critical physiological processes, including food digestion, immune system development, and metabolic homeostasis. However, despite the key role of the gut microbiome in human health, the functional impact of lead exposure on the gut microbiome has not been studied. The aim of this study is to define gut microbiome toxicity induced by lead exposure in C57BL/6 mice using multiomics approaches, including 16S rRNA sequencing, whole genome metagenomics sequencing, and gas chromatography-mass spectrometry (GC-MS) metabolomics. 16S rRNA sequencing revealed that lead exposure altered the gut microbiome trajectory and phylogenetic diversity. Metagenomics sequencing and metabolomics profiling showed that numerous metabolic pathways, including vitamin E, bile acids, nitrogen metabolism, energy metabolism, oxidative stress, and the defense/detoxification mechanism, were significantly disturbed by lead exposure. These perturbed molecules and pathways may have important implications for lead toxicity in the host. Taken together, these results demonstrated that lead exposure not only altered the gut microbiome community structures/diversity but also greatly affected metabolic functions, leading to gut microbiome toxicity.

Bile acids, obesity, and the metabolic syndrome

Bile acids are increasingly recognized as key regulators of systemic metabolism. While bile acids have long been known to play important and direct roles in nutrient absorption, bile acids also serve as signalling molecules. Bile acid interactions with the nuclear hormone receptor farnesoid X receptor (FXR) and the membrane receptor G-protein-coupled bile acid receptor 5 (TGR5) can regulate incretin hormone and fibroblast growth factor 19 (FGF19) secretion, cholesterol metabolism, and systemic energy expenditure. Bile acid levels and distribution are altered in type 2 diabetes and increased following bariatric procedures, in parallel with reduced body weight and improved insulin sensitivity and glycaemic control. Thus, modulation of bile acid levels and signalling, using bile acid binding resins, TGR5 agonists, and FXR agonists, may serve as a potent therapeutic approach for the treatment of obesity, type 2 diabetes, and other components of the metabolic syndrome in humans.