Impacts of maternal microbiota and microbial metabolites on fetal intestine, brain, and placenta.

BACKGROUND: The maternal microbiota modulates fetal development, but the mechanisms of these earliest host-microbe interactions are unclear. To investigate the developmental impacts of maternal microbial metabolites, we compared full-term fetuses from germ-free and specific pathogen-free mouse dams by gene expression profiling and non-targeted metabolomics. RESULTS: In the fetal intestine, critical genes mediating host-microbe interactions, innate immunity, and epithelial barrier were differentially expressed. Interferon and inflammatory signaling genes were downregulated in the intestines and brains of the fetuses from germ-free dams. The expression of genes related to neural system development and function, translation and RNA metabolism, and regulation of energy metabolism were significantly affected. The gene coding for the insulin-degrading enzyme (Ide) was most significantly downregulated in all tissues. In the placenta, genes coding for prolactin and other essential regulators of pregnancy were downregulated in germ-free dams. These impacts on gene expression were strongly associated with microbially modulated metabolite concentrations in the fetal tissues. Aryl sulfates and other aryl hydrocarbon receptor ligands, the trimethylated compounds TMAO and 5-AVAB, Glu-Trp and other dipeptides, fatty acid derivatives, and the tRNA nucleobase queuine were among the compounds strongly associated with gene expression differences. A sex difference was observed in the fetal responses to maternal microbial status: more genes were differentially regulated in male fetuses than in females. CONCLUSIONS: The maternal microbiota has a major impact on the developing fetus, with male fetuses potentially more susceptible to microbial modulation. The expression of genes important for the immune system, neurophysiology, translation, and energy metabolism are strongly affected by the maternal microbial status already before birth. These impacts are associated with microbially modulated metabolites. We identified several microbial metabolites which have not been previously observed in this context. Many of the potentially important metabolites remain to be identified.

Maternal microbiota-derived metabolic profile in fetal murine intestine, brain and placenta.

BACKGROUND: The maternal microbiota affects the development of the offspring by microbial metabolites translocating to the fetus. To reveal the spectrum of these molecular mediators of the earliest host-microbe interactions, we compared placenta, fetal intestine and brain from germ-free (GF) and specific pathogen free (SPF) mouse dams by non-targeted metabolic profiling. RESULTS: One hundred one annotated metabolites and altogether 3680 molecular features were present in significantly different amounts in the placenta and/or fetal organs of GF and SPF mice. More than half of these were more abundant in the SPF organs, suggesting their microbial origin or a metabolic response of the host to the presence of microbes. The clearest separation was observed in the placenta, but most of the molecular features showed significantly different levels also in the fetal intestine and/or brain. Metabolites that were detected in lower amounts in the GF fetal organs included 5-aminovaleric acid betaine, trimethylamine N-oxide, catechol-O-sulphate, hippuric and pipecolic acid. Derivatives of the amino acid tryptophan, such as kynurenine, 3-indolepropionic acid and hydroxyindoleacetic acid, were also less abundant in the absence of microbiota. Ninety-nine molecular features were detected only in the SPF mice. We also observed several molecular features which were more abundant in the GF mice, possibly representing precursors of microbial metabolites or indicators of a metabolic response to the absence of microbiota. CONCLUSIONS: The maternal microbiota has a profound impact on the fetal metabolome. Our observations suggest the existence of a multitude of yet unidentified microbially modified metabolites which pass through the placenta into the fetus and potentially influence fetal development.

Effectiveness of mepolizumab in patients with severe eosinophilic asthma: results from real-world clinical practice in Finland.

OBJECTIVES: Mepolizumab treatment provides clinical benefits for patients with severe eosinophilic asthma in randomized controlled trials. However, real-world data for patients in Finland are lacking. METHODS: This retrospective, non-interventional, chart review study included patients with severe eosinophilic asthma ≥18 years of age initiating mepolizumab between January 1, 2016 and January 31, 2019 at three investigational sites in Finland. Patient characteristics during the 12 months prior to mepolizumab initiation (baseline) were recorded and primary and secondary endpoints included changes from baseline in disease outcomes during follow-up (up to 24 months following mepolizumab initiation). Exploratory endpoints included association between patient characteristics and exacerbation frequency/annual cumulative oral corticosteroid (OCS) dose. RESULTS: Overall, 51 patients were included (mean 17.8 months follow-up). At baseline, patients had a mean (standard deviation) blood eosinophil count of 550 (410) cells/µL; impaired lung function and health-related quality of life; poor symptom control; frequent exacerbations (2.78/year); and 90% were using OCS (mean: 9.80 mg/day). At the last follow-up visit, reductions from baseline in blood eosinophil count (84%) and fractional exhaled nitric oxide (26%) were observed, as were improvements in Asthma Quality of Life Questionnaire score (36%) and Asthma Control Test score (34%). Reductions in the mean number of annual exacerbations (82%) and mean daily OCS dose (39%) were also seen; reductions were observed even after adjustment for several patient baseline characteristics. CONCLUSIONS: Results are consistent with previous randomized clinical trials, indicating that Finnish patients experience clinically relevant improvements when treated with mepolizumab in real-world clinical practice.

Putative metabolites involved in the beneficial effects of wholegrain cereal: Nontargeted metabolite profiling approach.

BACKGROUND AND AIMS: Wholegrain cereals have been implicated in the reduction of lifestyle-related chronic diseases risk including cardiovascular diseases and type 2 diabetes. Molecular mechanisms responsible for the beneficial health effects are not entirely understood. The aims of this study were 1) to identify new potential plasma biomarker candidate metabolites of wholegrain cereal foods intake and 2) to examine whether some putative metabolites associated with wholegrain foods intake may play a role in the improvement of cardiometabolic risk factors. METHODS AND RESULTS: Analysis have been conducted in 54 individuals with metabolic syndrome of both genders, age 40-65 years, randomly assigned to 2 dietary interventions lasting 12-week: 1) wholegrain enriched diet (n = 28), and 2) refined-wheat cereals diet (control diet) (n = 26). Nontargeted metabolite profiling analysis was performed on fasting plasma samples collected at baseline and at the end of the experimental diets. Our data show that, at the end of the intervention, a higher intake of wholegrain (tertile 3) was significantly associated with a marked increase in several lipid compounds, as PC (20:4/16:1), LPC (20:4), LPC (22:6), LPC (18:3), LPC (22:5), and a phenolic compound (P < .05 for all). In the wholegrain group, higher concentrations of these metabolites (tertile 3 vs tertile 1 of each metabolite) were significantly associated with lower postprandial insulin and triglyceride responses (P < .05) by 29% and 37%, respectively. CONCLUSION: These observations suggest a possible role of lipid and polyphenol metabolites in the postprandial metabolic benefits of wholegrains in subjects at high risk of cardiovascular disease. In addition, they provide insight into the role of these metabolites as potential candidate biomarkers of wholegrain foods. The study was registered on ClinicalTrials.gov (identifier: NCT00945854).

Factors affecting intake, metabolism and health benefits of phenolic acids: do we understand individual variability?

INTRODUCTION: Phenolic acids are important phenolic compounds widespread in foods, contributing to nutritional and organoleptic properties. FACTORS AFFCETING INDIVIDUAL VARIABILITY: The bioavailability of these compounds depends on their free or conjugated presence in food matrices, which is also affected by food processing. Phenolic acids undergo metabolism by the host and residing intestinal microbiota, which causes conjugations and structural modifications of the compounds. Human responses, metabolite profiles and health responses of phenolics, show considerable individual variation, which is affected by absorption, metabolism and genetic variations of subjects. OPINION: A better understanding of the gut-host interplay and microbiome biochemistry is becoming highly relevant in understanding the impact of diet and its constituents. It is common to study metabolism and health benefits separately, with some exceptions; however, it should be preferred that health responders and non-responders are studied in combination with explanatory metabolite profiles and gene variants. This approach could turn interindividual variation from a problem in human research to an asset for research on personalized nutrition.

Mass spectrometry-based analysis of whole-grain phytochemicals.

Whole grains are a rich source of several classes of phytochemicals, such as alkylresorcinols, benzoxazinoids, flavonoids, lignans, and phytosterols. A high intake of whole grains has been linked to a reduced risk of some major noncommunicable diseases, and it has been postulated that a complex mixture of phytochemicals works in synergy to generate beneficial health effects. Mass spectrometry, especially when coupled with liquid chromatography, is a widely used method for the analysis of phytochemicals owing to its high sensitivity and dynamic range. In this review, the current knowledge of the mass spectral properties of the most important classes of phytochemicals found in cereals of common wheat, barley, oats, and rye is discussed.

Hyaluronan-positive plasma membrane protrusions exist on mesothelial cells in vivo.

Previous observations of our research group showed that HAS2 and HAS3 overexpression in cultured cells induces the formation of long and numerous microvillus-like cell protrusions, which are present also in cultured cell types with naturally high hyaluronan secretion and the cell protrusions resemble those found in mesothelial cells. The aim of this study was to investigate whether these hyaluronan secreting, actin-dependent protrusions exist also in vivo. It was found that rat mesothelium in vivo is positive for hyaluronan and Has1-3. Also microvilli in rat mesothelium and live primary cultures of mesothelial cells were found to be hyaluronan positive, and the cells expressed all Has isoforms. Furthermore, ultrastructure of the cell protrusions in rat mesothelium was similar to that induced by overexpression of HAS2 and HAS3, and the number and orientation of actin filaments supporting the cell protrusions was identical. The results of this study show that HA-positive protrusions exist in vivo and support the idea that hyaluronan secretion from plasma membrane protrusions is a general process. This mechanism is potentially crucial for the normal function and maintenance of tissues and body fluids and may be utilized in many therapeutic applications.

Cell protrusions induced by hyaluronan synthase 3 (HAS3) resemble mesothelial microvilli and share cytoskeletal features of filopodia.

Previous studies have shown that overexpression of enzymatically active GFP-HAS induces the growth of long, slender protrusions that share many features of both filopodia and microvilli. These protrusions are dependent on continuing hyaluronan synthesis, and disrupt upon digestion of hyaluronan by hyaluronidase. However, complete understanding of their nature is still missing. This work shows that the protrusions on rat peritoneal surface are ultrastructurally indistinguishable from those induced by GFP-HAS3 in MCF-7 cells. Analysis of the actin-associated proteins villin, ezrin, espin, fascin, and Myo10 indicated that the HAS3-induced protrusions share most cytoskeletal features with filopodia, but they do not require adherence to the substratum like traditional filopodia. GFP-HAS3 overexpression was found to markedly enhance filamentous actin in the protrusions and their cortical basis. Analysis of the protrusion dynamics after enzymatic digestion of hyaluronan revealed that while GFP-HAS3 escape from the protrusions and the protrusion collapse takes place immediately, the complete retraction of the protrusions occurs more slowly. This finding also suggests that hyaluronan chain maintains HAS3 in the plasma membrane. The results of this work suggest that protrusions similar to those of HAS3 overexpressing cells in vitro exist also in cells with active hyaluronan synthesis in vivo. These protrusions are similar to common filopodia but are independent of substratum attachment due to the extracellular scaffolding by the hyaluronan coat that accounts for the growth and maintenance of these structures, previously associated to invasion, adhesion and multidrug resistance.

Hyaluronan production enhances shedding of plasma membrane-derived microvesicles.

Many cell types secrete plasma membrane-bound microvesicles, suggested to play an important role in tissue morphogenesis, wound healing, and cancer spreading. However, the mechanisms of their formation have remained largely unknown. It was found that the tips of long microvilli induced in cells by overexpression of hyaluronan synthase 3 (HAS3) were detach into the culture medium as microvesicles. Moreover, several cell types with naturally active hyaluronan synthesis released high numbers of plasma membrane-derived vesicles, and inhibition of hyaluronan synthesis reduced their formation. The vesicles contained HAS, and were covered with a thick hyaluronan coat, a part of which was retained even after purification with high-speed centrifugation. HAS3 overexpressing MDCK cells cultured in a 3-D matrix as epithelial cysts released large amounts of HAS- and hyaluronan-positive vesicles from their basal surfaces into the extracellular matrix. As far as we know, hyaluronan synthesis is one of the first molecular mechanisms shown to stimulate the production of microvesicles. The microvesicles have a potential to deliver the hyaluronan synthase machinery and membrane and cytoplasmic materials to other cells, influencing tissue regeneration, inflammation and tumor progression.

Lipophilic and Hydrophilic Metabolites as Descriptors of Different Coffee Beverages.

Coffee is a widely consumed beverage rich in bioactive phytochemicals. This study investigated the effect of brewing method on the profile of potential bioactive compounds in different coffee beverages using metabolomics and lipidomics based on UHPLC-MS/QTOF. The oil contents of the espresso coffee (EC), pot coffee (PC), instant coffee (IC), and filter coffee (FC) beverages studied were 0.13% ± 0.002, 0.12% ± 0.001, 0.04% ± 0.002, and 0.03% ± 0.003, respectively. Univariate analysis indicated significant differences (P < 0.001) in oil content when EC and PC beverages were compared with IC and FC beverages. Principal component analysis revealed similarities in the lipid profiles of FC and EC beverages and the hydrophilic profiles of PC and FC beverages. The EC beverage had the highest intensity of hydrophilic compounds such as adenine, theobromine, chlorogenic acid, and caffeine. The PC beverage was the most abundant in triglycerides, phosphatidylcholine, and diterpenes. Cafestol and kahweol esters, but not their free forms, were the most abundant diterpenes in the PC beverage. This work provides information on the differences in the profile of potentially bioactive compounds in four commonly consumed coffee beverage types and, thus, on the possible differences in the health effects of these coffee beverage types.

Metabolic changes in response to varying whole-grain wheat and rye intake.

Epidemiological studies have shown associations between whole-grain intake and lowered disease risk. A sufficient level of whole-grain intake to reach the health benefits has not been established, and there is limited knowledge about the impact of whole-grain intake on metabolite levels. In this clinical intervention study, we aimed to identify plasma and urine metabolites associated with two different intake levels of whole-grain wheat and rye and to correlate them with clinical plasma biomarkers. Healthy volunteers (N = 68) were divided into two groups receiving either whole-grain wheat or whole-grain rye in two four-week interventions with 48 and 96 g/d of whole grains consumed. The metabolomics of the plasma samples was performed with UPLC-QTOF-MS. Plasma alkylresorcinols were quantified with GC-MS and plasma and urinary mammalian lignans with HPLC-ECD. The high-dose intervention impacted the metabolite profile, including microbial metabolites, more in the rye-enriched diet compared with wheat. Among the increased metabolites were alkylresorcinol glucuronides, sinapyl alcohol, and pipecolic acid betaine, while the decreased metabolites included acylcarnitines and ether lipids. Plasma alkylresorcinols, urinary enterolactone, and total mammalian lignans reflected the study diets in a dose-dependent manner. Several key metabolites linked with whole-grain consumption and gut microbial metabolism increased in a linear manner between the two interventions. The results reveal that an increase in whole-grain intake, particularly rye, is strongly reflected in the metabolite profile, is correlated with clinical variables, and suggests that a diet rich in whole grains promotes the growth and/or metabolism of microbes producing potentially beneficial microbial metabolites.

Nutritional metabolomics: Recent developments and future needs.

Metabolomics has rapidly been adopted as one of the key methods in nutrition research. This review focuses on the recent developments and updates in the field, including the analytical methodologies that encompass improved instrument sensitivity, sampling techniques and data integration (multiomics). Metabolomics has advanced the discovery and validation of dietary biomarkers and their implementation in health research. Metabolomics has come to play an important role in the understanding of the role of small molecules resulting from the diet-microbiota interactions when gut microbiota research has shifted towards improving the understanding of the activity and functionality of gut microbiota rather than composition alone. Currently, metabolomics plays an emerging role in precision nutrition and the recent developments therein are discussed.

Associations of altered hepatic gene expression in American lifestyle-induced obesity syndrome diet-fed mice with metabolic changes during NAFLD development and progression.

Non-alcoholic fatty liver disease (NAFLD) pathogenesis remains poorly understood due to the complex metabolic and inflammatory changes in the liver. This study aimed to elucidate hepatic events related to inflammation and lipid metabolism and their linkage with metabolic alterations during NAFLD in American lifestyle-induced obesity syndrome (ALIOS) diet-fed mice. Forty-eight C57BL/6J male mice were fed with ALIOS diet (n=24) or control chow diet (n=24) for 8, 12, and 16 weeks. At the end of each timepoint, eight mice were sacrificed where plasma and liver were collected. Hepatic fat accumulation was followed using magnetic resonance imaging and confirmed with histology. Further, targeted gene expression and non-targeted metabolomics analysis were conducted. Our results showed higher hepatic steatosis, body weight, energy consumption, and liver mass in ALIOS diet-fed mice compared to control mice. ALIOS diet altered expression of genes related to inflammation (Tnfa and IL-6) and lipid metabolism (Cd36, Fasn, Scd1, Cpt1a, and Ppara). Metabolomics analysis indicated decrease of lipids containing polyunsaturated fatty acids such as LPE(20:5) and LPC(20:5) with increase of other lipid species such as LPI(16:0) and LPC(16:2) and peptides such as alanyl-phenylalanine and glutamyl-arginine. We further observed novel correlations between different metabolites including sphingolipid, lysophospholipids, peptides, and bile acid with inflammation, lipid uptake and synthesis. Together with the reduction of antioxidant metabolites and gut microbiota-derived metabolites contribute to NAFLD development and progression. The combination of non-targeted metabolomics with gene expression in future studies can further identify key metabolic routes during NAFLD which could be the targets of potential novel therapeutics.

HAS3-induced accumulation of hyaluronan in 3D MDCK cultures results in mitotic spindle misorientation and disturbed organization of epithelium.

The amount of hyaluronan (HA) is low in simple epithelia under normal conditions, but during tumorigenesis, trauma or inflammation HA is increased on the epithelial cells and surrounding stroma. Excessive HA in epithelia is suggested to interfere with cell-cell adhesions, resulting in disruption of the epithelial barrier function. In addition, stimulated HA synthesis has been correlated with epithelial-to-mesenchymal transition and invasion of cancer cells. However, the effects of HA overload on normal epithelial morphogenesis have not been characterized in detail. Madin-Darby canine kidney (MDCK) cells form polarized epithelial cysts, when grown in a 3-dimensional (3D) matrix. These cells were used to investigate whether stimulated HA synthesis, induced by stable overexpression of GFP-HAS3, influences cell polarization and epithelial morphogenesis. GFP-HAS3 expression in polarized MDCK cells resulted in active HA secretion at apical and basolateral membrane domains. HA-deposits interfered with the formation of cell-cell junctions, resulting in impaired barrier function. In 3D cyst cultures, HA accumulated into apical lumina and was also secreted from the basal side. The HAS3-expressing cysts failed to form a single lumen and instead displayed multiple small lumina. This phenotype was correlated with aberrant mitotic spindle orientation in dividing cells. The results of this study indicate that excess pericellular HA disturbs the normal cell-cell and cell-ECM interactions in simple epithelia, leading to aberrant epithelial morphogenesis. The morphological abnormalities observed in 3D epithelial cultures upon stimulated HAS3 expression may be related to premalignant changes, including intraluminal invasion and deregulated epithelialization, probably mediated by the mitotic spindle orientation defects.

Diet- and microbiota-related metabolite, 5-aminovaleric acid betaine (5-AVAB), in health and disease.

5-Aminovaleric acid betaine (5-AVAB) is a trimethylated compound associated with the gut microbiota, potentially produced endogenously, and related to the dietary intake of certain foods such as whole grains. 5-AVAB accumulates within the metabolically active tissues and has been typically found in higher concentrations in the heart, muscle, and brown adipose tissue. Furthermore, 5-AVAB has been associated with positive health effects such as fetal brain development, insulin secretion, and reduced cancer risk. However, it also has been linked with some negative health outcomes such as cardiovascular disease and fatty liver disease. At the cellular level, 5-AVAB can influence cellular energy metabolism by reducing ß-oxidation of fatty acids. This review will focus on the metabolic role of 5-AVAB with respect to both physiology and pathology. Moreover, the analytics and origin of 5-AVAB and related compounds will be reviewed.

Microbiota-derived metabolites as drivers of gut-brain communication.

Alterations in the gut microbiota composition have been associated with a range of neurodevelopmental, neurodegenerative, and neuropsychiatric disorders. The gut microbes transform and metabolize dietary- and host-derived molecules generating a diverse group of metabolites with local and systemic effects. The bi-directional communication between brain and the microbes residing in the gut, the so-called gut-brain axis, consists of a network of immunological, neuronal, and endocrine signaling pathways. Although the full variety of mechanisms of the gut-brain crosstalk is yet to be established, the existing data demonstrates that a single metabolite or its derivatives are likely among the key inductors within the gut-brain axis communication. However, more research is needed to understand the molecular mechanisms underlying how gut microbiota associated metabolites alter brain functions, and to examine if different interventional approaches targeting the gut microbiota could be used in prevention and treatment of neurological disorders, as reviewed herein.Abbreviations:4-EPS 4-ethylphenylsulfate; 5-AVA(B) 5-aminovaleric acid (betaine); Aß Amyloid beta protein; AhR Aryl hydrocarbon receptor; ASD Autism spectrum disorder; BBB Blood-brain barrier; BDNF Brain-derived neurotrophic factor; CNS Central nervous system; GABA É£-aminobutyric acid; GF Germ-free; MIA Maternal immune activation; SCFA Short-chain fatty acid; 3M-4-TMAB 3-methyl-4-(trimethylammonio)butanoate; 4-TMAP 4-(trimethylammonio)pentanoate; TMA(O) Trimethylamine(-N-oxide); TUDCA Tauroursodeoxycholic acid; ZO Zonula occludens proteins.

Effects of exercise on NAFLD using non-targeted metabolomics in adipose tissue, plasma, urine, and stool.

The mechanisms by which exercise benefits patients with non-alcoholic fatty liver disease (NAFLD), the most common liver disease worldwide, remain poorly understood. A non-targeted liquid chromatography-mass spectrometry (LC-MS)-based metabolomics analysis was used to identify metabolic changes associated with NAFLD in humans upon exercise intervention (without diet change) across four different sample types-adipose tissue (AT), plasma, urine, and stool. Altogether, 46 subjects with NAFLD participated in this randomized controlled intervention study. The intervention group (n = 21) performed high-intensity interval training (HIIT) for 12 weeks while the control group (n = 25) kept their sedentary lifestyle. The participants' clinical parameters and metabolic profiles were compared between baseline and endpoint. HIIT significantly decreased fasting plasma glucose concentration (p = 0.027) and waist circumference (p = 0.028); and increased maximum oxygen consumption rate and maximum achieved workload (p < 0.001). HIIT resulted in sample-type-specific metabolite changes, including accumulation of amino acids and their derivatives in AT and plasma, while decreasing in urine and stool. Moreover, many of the metabolite level changes especially in the AT were correlated with the clinical parameters monitored during the intervention. In addition, certain lipids increased in plasma and decreased in the stool. Glyco-conjugated bile acids decreased in AT and urine. The 12-week HIIT exercise intervention has beneficial ameliorating effects in NAFLD subjects on a whole-body level, even without dietary changes and weight loss. The metabolomics analysis applied to the four different sample matrices provided an overall view on several metabolic pathways that had tissue-type specific changes after HIIT intervention in subjects with NAFLD. The results highlight especially the role of AT in responding to the HIIT challenge, and suggest that altered amino acid metabolism in AT might play a critical role in e.g. improving fasting plasma glucose concentration.Trial registration ClinicalTrials.gov (NCT03995056).

Identification and Distribution of Sterols, Bile Acids, and Acylcarnitines by LC-MS/MS in Humans, Mice, and Pigs-A Qualitative Analysis.

Sterols, bile acids, and acylcarnitines are key players in human metabolism. Precise annotations of these metabolites with mass spectrometry analytics are challenging because of the presence of several isomers and stereoisomers, variability in ionization, and their relatively low concentrations in biological samples. Herein, we present a sensitive and simple qualitative LC-MS/MS (liquid chromatography with tandem mass spectrometry) method by utilizing a set of pure chemical standards to facilitate the identification and distribution of sterols, bile acids, and acylcarnitines in biological samples including human stool and plasma; mouse ileum, cecum, jejunum content, duodenum content, and liver; and pig bile, proximal colon, cecum, heart, stool, and liver. With this method, we detected 24 sterol, 32 bile acid, and 27 acylcarnitine standards in one analysis that were separated within 13 min by reversed-phase chromatography. Further, we observed different sterol, bile acid, and acylcarnitine profiles for the different biological samples across the different species. The simultaneous detection and annotation of sterols, bile acids, and acylcarnitines from reference standards and biological samples with high precision represents a valuable tool for screening these metabolites in routine scientific research.

Metabolite Pattern Derived from Lactiplantibacillus plantarum-Fermented Rye Foods and In Vitro Gut Fermentation Synergistically Inhibits Bacterial Growth.

SCOPE: Fermentation improves many food characteristics using microbes, such as lactic acid bacteria (LAB). Recent studies suggest fermentation may also enhance the health properties, but mechanistic evidence is lacking. The study aims to identify a metabolite pattern reproducibly produced during sourdough and in vitro colonic fermentation of various whole-grain rye products and how it affects the growth of bacterial species of potential importance to health and disease. METHODS AND RESULTS: The study uses Lactiplantibacillus plantarum DSMZ 13890 strain, previously shown to favor rye as its substrate. Using LC-MS metabolomics, the study finds seven microbial metabolites commonly produced during the fermentations, including dihydroferulic acid, dihydrocaffeic acid, and five amino acid metabolites, and stronger inhibition is achieved when exposing the bacteria to a mixture of the metabolites in vitro compared to individual compound exposures. CONCLUSION: The study suggests that metabolites produced by LAB may synergistically modulate the local microbial ecology, such as in the gut. This could provide new hypotheses on how fermented foods influence human health via diet-microbiota interactions.

Tissue-wide metabolomics reveals wide impact of gut microbiota on mice metabolite composition.

The essential role of gut microbiota in health and disease is well recognized, but the biochemical details that underlie the beneficial impact remain largely undefined. To maintain its stability, microbiota participates in an interactive host-microbiota metabolic signaling, impacting metabolic phenotypes of the host. Dysbiosis of microbiota results in alteration of certain microbial and host metabolites. Identifying these markers could enhance early detection of certain diseases. We report LC-MS based non-targeted metabolic profiling that demonstrates a large effect of gut microbiota on mammalian tissue metabolites. It was hypothesized that gut microbiota influences the overall biochemistry of host metabolome and this effect is tissue-specific. Thirteen different tissues from germ-free (GF) and conventionally-raised (MPF) C57BL/6NTac mice were selected and their metabolic differences were analyzed. Our study demonstrated a large effect of microbiota on mammalian biochemistry at different tissues and resulted in statistically-significant modulation of metabolites from multiple metabolic pathways (p ≤ 0.05). Hundreds of molecular features were detected exclusively in one mouse group, with the majority of these being unique to specific tissue. A vast metabolic response of host to metabolites generated by the microbiota was observed, suggesting gut microbiota has a direct impact on host metabolism.