Endothelial cell-derived oxysterol ablation attenuates experimental autoimmune encephalomyelitis.

The vasculature is a key regulator of leukocyte trafficking into the central nervous system (CNS) during inflammatory diseases including multiple sclerosis (MS). However, the impact of endothelial-derived factors on CNS immune responses remains unknown. Bioactive lipids, in particular oxysterols downstream of Cholesterol-25-hydroxylase (Ch25h), promote neuroinflammation but their functions in the CNS are not well-understood. Using floxed-reporter Ch25h knock-in mice, we trace Ch25h expression to CNS endothelial cells (ECs) and myeloid cells and demonstrate that Ch25h ablation specifically from ECs attenuates experimental autoimmune encephalomyelitis (EAE). Mechanistically, inflamed Ch25h-deficient CNS ECs display altered lipid metabolism favoring polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC) expansion, which suppresses encephalitogenic T lymphocyte proliferation. Additionally, endothelial Ch25h-deficiency combined with immature neutrophil mobilization into the blood circulation nearly completely protects mice from EAE. Our findings reveal a central role for CNS endothelial Ch25h in promoting neuroinflammation by inhibiting the expansion of immunosuppressive myeloid cell populations.

Human milk oligosaccharide 2'-fucosyllactose protects against high-fat diet-induced obesity by changing intestinal mucus production, composition and degradation linked to changes in gut microbiota and faecal proteome profiles in mice.

OBJECTIVE: To decipher the mechanisms by which the major human milk oligosaccharide (HMO), 2'-fucosyllactose (2'FL), can affect body weight and fat mass gain on high-fat diet (HFD) feeding in mice. We wanted to elucidate whether 2'FL metabolic effects are linked with changes in intestinal mucus production and secretion, mucin glycosylation and degradation, as well as with the modulation of the gut microbiota, faecal proteome and endocannabinoid (eCB) system. RESULTS: 2'FL supplementation reduced HFD-induced obesity and glucose intolerance. These effects were accompanied by several changes in the intestinal mucus layer, including mucus production and composition, and gene expression of secreted and transmembrane mucins, glycosyltransferases and genes involved in mucus secretion. In addition, 2'FL increased bacterial glycosyl hydrolases involved in mucin glycan degradation. These changes were linked to a significant increase and predominance of bacterial genera Akkermansia and Bacteroides, different faecal proteome profile (with an upregulation of proteins involved in carbon, amino acids and fat metabolism and a downregulation of proteins involved in protein digestion and absorption) and, finally, to changes in the eCB system. We also investigated faecal proteomes from lean and obese humans and found similar changes observed comparing lean and obese mice. CONCLUSION: Our results show that the HMO 2'FL influences host metabolism by modulating the mucus layer, gut microbiota and eCB system and propose the mucus layer as a new potential target for the prevention of obesity and related disorders.

Dysosmobacter welbionis effects on glucose, lipid, and energy metabolism are associated with specific bioactive lipids.

The newly identified bacterium Dysosmobacter welbionis J115T improves host metabolism in high-fat diet (HFD)-fed mice. To investigate mechanisms, we used targeted lipidomics to identify and quantify bioactive lipids produced by the bacterium in the culture medium, the colon, the brown adipose tissue (BAT), and the blood of mice. In vitro, we compared the bioactive lipids produced by D. welbionis J115T versus the probiotic strain Escherichia coli Nissle 1917. D. welbionis J115T administration reduced body weight, fat mass gain, and improved glucose tolerance and insulin resistance in HFD-fed mice. In vitro, 19 bioactive lipids were highly produced by D. welbionis J115T as compared to Escherichia coli Nissle 1917. In the plasma, 13 lipids were significantly changed by the bacteria. C18-3OH was highly present at the level of the bacteria, but decreased by HFD treatment in the plasma and normalized in D. welbionis J115T-treated mice. The metabolic effects were associated with a lower whitening of the BAT. In the BAT, HFD decreased the 15-deoxy-Δ12,14-prostaglandin J2, a peroxisome proliferator-activated receptor (PPAR-γ) agonist increased by 700% in treated mice as compared to HFD-fed mice. Several genes controlled by PPAR-γ were upregulated in the BAT. In the colon, HFD-fed mice had a 60% decrease of resolvin D5, whereas D. welbionis J115T-treated mice exhibited a 660% increase as compared to HFD-fed mice. In a preliminary experiment, we found that D. welbionis J115T improves colitis. In conclusion, D. welbionis J115T influences host metabolism together with several bioactive lipids known as PPAR-γ agonists.

Identification of an endocannabinoid gut-brain vagal mechanism controlling food reward and energy homeostasis.

The regulation of food intake, a sine qua non requirement for survival, thoroughly shapes feeding and energy balance by integrating both homeostatic and hedonic values of food. Unfortunately, the widespread access to palatable food has led to the development of feeding habits that are independent from metabolic needs. Among these, binge eating (BE) is characterized by uncontrolled voracious eating. While reward deficit seems to be a major contributor of BE, the physiological and molecular underpinnings of BE establishment remain elusive. Here, we combined a physiologically relevant BE mouse model with multiscale in vivo approaches to explore the functional connection between the gut-brain axis and the reward and homeostatic brain structures. Our results show that BE elicits compensatory adaptations requiring the gut-to-brain axis which, through the vagus nerve, relies on the permissive actions of peripheral endocannabinoids (eCBs) signaling. Selective inhibition of peripheral CB1 receptors resulted in a vagus-dependent increased hypothalamic activity, modified metabolic efficiency, and dampened activity of mesolimbic dopamine circuit, altogether leading to the suppression of palatable eating. We provide compelling evidence for a yet unappreciated physiological integrative mechanism by which variations of peripheral eCBs control the activity of the vagus nerve, thereby in turn gating the additive responses of both homeostatic and hedonic brain circuits which govern homeostatic and reward-driven feeding. In conclusion, we reveal that vagus-mediated eCBs/CB1R functions represent an interesting and innovative target to modulate energy balance and counteract food-reward disorders.

A novel missense variant in ATP11C is associated with reduced red blood cell phosphatidylserine flippase activity and mild hereditary hemolytic anemia.

Adenosine Triphosphatase (ATPase) Phospholipid Transporting 11C gene (ATP11C) encodes the major phosphatidylserine (PS) flippase in human red blood cells (RBCs). Flippases actively transport phospholipids (e.g., PS) from the outer to the inner leaflet to establish and maintain phospholipid asymmetry of the lipid bilayer of cell membranes. This asymmetry is crucial for survival since externalized PS triggers phagocytosis by splenic macrophages. Here we report on pathophysiological consequences of decreased flippase activity, prompted by a patient with hemolytic anemia and hemizygosity for a novel c.2365C > T p.(Leu789Phe) missense variant in ATP11C. ATP11C protein expression was strongly reduced by 58% in patient-derived RBC ghosts. Furthermore, functional characterization showed only 26% PS flippase activity. These results were confirmed by recombinant mutant ATP11C protein expression in HEK293T cells, which was decreased to 27% compared to wild type, whereas PS-stimulated ATPase activity was decreased by 57%. Patient RBCs showed a mild increase in PS surface exposure when compared to control RBCs, which further increased in the most dense RBCs after RBC storage stress. The increase in PS was not due to higher global membrane content of PS or other phospholipids. In contrast, membrane lipid lateral distribution showed increased abundance of cholesterol-enriched domains in RBC low curvature areas. Finally, more dense RBCs and subtle changes in RBC morphology under flow hint toward alterations in flow behavior of ATP11C-deficient RBCs. Altogether, ATP11C deficiency is the likely cause of hemolytic anemia in our patient, thereby underlining the physiological role and relevance of this flippase in human RBCs.

Set up and validation of a sensitive method to quantify prostaglandins, prostaglandin-glycerol esters and prostaglandin-ethanolamides, as well as their respective precursors.

Arachidonic acid-derived prostaglandins are widely studied for their role in inflammation. However, besides arachidonic acid, other arachidonic moiety-containing lipids can be metabolized by COX-2. Indeed, the endocannabinoids 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (anandamide, AEA) can follow the same biochemical pathways than arachidonic acid leading to the formation of prostaglandin-glycerol esters (PG-G) and prostaglandin-ethanolamides (or prostamides, PG-EA), respectively. The data reported so far support the interest of these bioactive lipids in inflammatory conditions. However, there is only a handful of methods described for their quantification in biological matrices. Moreover, given the shared biochemical pathways for arachidonic acid, 2-AG and AEA, a method allowing for the quantification of these precursors and the corresponding prostaglandin derivatives appears as largely needed. Thus, we report here the development and validation of a single run UPLC-MS/MS quantification method allowing the quantification of these endocannabinoids-derived mediators together with the classical prostaglandin. Moreover, we applied the method to the quantification of these lipids in vitro (using lipopolysaccharides-activated J774 macrophage cells) and in vivo in several tissues from DSS-induced colitis mice. This femtomole-range method should improve the understanding of the interaction between these lipid mediators and inflammation.

Genetic Polymorphisms in SLCO2B1 and ABCC1 Conjointly Modulate Atorvastatin Intracellular Accumulation in HEK293 Recombinant Cell Lines.

BACKGROUND: Although atorvastatin (ATV) is well-tolerated, patients may report muscle complaints. These are difficult to predict owing to high interindividual variability. Such side effects are linked to intramuscular accumulation of ATV. This study aimed to investigate the relative role of transporters expressed in muscle tissue in promoting or limiting drug access to cells. The impact of common single nucleotide polymorphisms (SNPs) in SLCO2B1 coding for OATP2B1 and ABCC1 coding for MRP1 on ATV transport was also evaluated. METHODS: HEK293 cells were stably transfected with plasmids containing cDNA encoding wild-type or variant SLCO2B1 and/or ABCC1 to generate single and double stable transfectant HEK293 recombinant models overexpressing variant or wild-type OATP2B1 (influx) and/or MRP1 (efflux) proteins. Variant plasmids were generated by site-directed mutagenesis. Expression analyses were performed to validate recombinant models. Accumulation and efflux experiments were performed at different concentrations. ATV was quantified by LC-MS/MS, and kinetic parameters were compared between single and double HEK transfectants expressing wild-type and variant proteins. RESULTS: The results confirm the involvement of OATP2B1 and MRP1 in ATV cellular transport because it was demonstrated that intracellular accumulation of ATV was boosted by OATP2B1 overexpression, whereas ATV accumulation was decreased by MRP1 overexpression. In double transfectants, it was observed that increased ATV intracellular accumulation driven by OATP2B1 influx was partially counteracted by MRP1 efflux. The c.935G > A SNP in SLCO2B1 was associated with decreased ATV OATP2B1-mediated influx, whereas the c.2012G > T SNP in ABCC1 seemed to increase MRP1 efflux activity against ATV. CONCLUSIONS: Intracellular ATV accumulation is regulated by OATP2B1 and MRP1 transporters, whose functionality is modulated by natural genetic variants. This is significant because it may play a role in ATV muscle side-effect susceptibility.

Lipid nanocapsules for the nose-to-brain delivery of the anti-inflammatory bioactive lipid PGD2-G.

Here, prostaglandin D2-glycerol ester (PGD2-G) was selected to target neuroinflammation. As PGD2-G is reported to have a short plasmatic half-life, we propose to use lipid nanocapsules (LNC) as vehicle to safely transport PGD2-G to the central nervous system (CNS). PGD2-G-loaded LNC (PGD2-G-LNC) reduced pro-inflammatory cytokine expression in activated microglial cells, even so after crossing a primary olfactory cell monolayer. A single nasal administration of PGD2-G-LNC in lipopolysaccharide (LPS)-treated mice reduced pro-inflammatory cytokine expression in the olfactory bulb. Coating LNC's surface with a cell-penetrating peptide, transactivator of transcription (TAT), increased its accumulation in the brain. Although TAT-coated PGD2-G-LNC modestly exerted its anti-inflammatory effect in a mouse model of multiple sclerosis similar to free PGD2-G after nasal administration, TAT-coated LNC surprisingly reduced the expression of pro-inflammatory chemokines in the CNS. These data propose LNC as an interesting drug delivery tool and TAT-coated PGD2-G-LNC remains a good candidate, in need of further work.

Dysosmobacter welbionis is a newly isolated human commensal bacterium preventing diet-induced obesity and metabolic disorders in mice.

OBJECTIVE: To investigate the abundance and the prevalence of Dysosmobacter welbionis J115T, a novel butyrate-producing bacterium isolated from the human gut both in the general population and in subjects with metabolic syndrome. To study the impact of this bacterium on host metabolism using diet-induced obese and diabetic mice. DESIGN: We analysed the presence and abundance of the bacterium in 11 984 subjects using four human cohorts (ie, Human Microbiome Project, American Gut Project, Flemish Gut Flora Project and Microbes4U). Then, we tested the effects of daily oral gavages with live D. welbionis J115T on metabolism and several hallmarks of obesity, diabetes, inflammation and lipid metabolism in obese/diabetic mice. RESULTS: This newly identified bacterium was detected in 62.7%-69.8% of the healthy population. Strikingly, in obese humans with a metabolic syndrome, the abundance of Dysosmobacter genus correlates negatively with body mass index, fasting glucose and glycated haemoglobin. In mice, supplementation with live D. welbionis J115T, but not with the pasteurised bacteria, partially counteracted diet-induced obesity development, fat mass gain, insulin resistance and white adipose tissue hypertrophy and inflammation. In addition, live D. welbionis J115T administration protected the mice from brown adipose tissue inflammation in association with increased mitochondria number and non-shivering thermogenesis. These effects occurred with minor impact on the mouse intestinal microbiota composition. CONCLUSIONS: These results suggest that D. welbionis J115T directly and beneficially influences host metabolism and is a strong candidate for the development of next-generation beneficial bacteria targeting obesity and associated metabolic diseases.

Effects of R-flurbiprofen and the oxygenated metabolites of endocannabinoids in inflammatory pain mice models.

Pain is one of the cardinal signs accompanying inflammation. The prostaglandins (PGs), synthetized from arachidonic acid by cyclooxygenase (COX)-2, are major bioactive lipids implicated in inflammation and pain. However, COX-2 is also able to metabolize other lipids, including the endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide (AEA), to give glycerol ester (PG-G) and ethanolamide (PG-EA) derivatives of the PGs. Consequently, COX-2 can be considered as a hub not only controlling PG synthesis, but also PG-G and PG-EA synthesis. As they were more recently characterized, these endocannabinoid metabolites are less studied in nociception compared to PGs. Interestingly R-profens, previously considered as inactive enantiomers of nonsteroidal anti-inflammatory drugs (NSAIDs), are substrate-selective COX inhibitors. Indeed, R-flurbiprofen can selectively block PG-G and PG-EA production, without affecting PG synthesis from COX-2. Therefore, we compared the effect of R-flurbiprofen and S-flurbiprofen in models of inflammatory pain triggered by local administration of lipopolysaccharides (LPS) and carrageenan in mice. Remarkably, the effects of flurbiprofen enantiomers on mechanical hyperalgesia seem to depend on (i) the inflammatory stimuli, (ii) the route of administration, and (iii) the timing of administration. We also assessed the effect of administration of the PG-Gs, PG-EAs, and PGs on LPS-induced mechanical hyperalgesia. Our data support the interest of studying the nonhydrolytic endocannabinoid metabolism in the context of inflammatory pain.

25-Hydroxycholesterol metabolism is altered by lung inflammation, and its local administration modulates lung inflammation in mice.

Inflammation is a critical component of many lung diseases including asthma and acute lung injury (ALI). Using high-performance liquid chromatography-mass spectrometry, we quantified the levels of oxysterols in two different murine models of lung diseases. These are lipid mediators derived from cholesterol and known to modulate immunity and inflammation. Interestingly, 25-hydroxycholesterol (25-OHC) was the only oxysterol with altered levels during lung inflammation, and its levels were differently affected according to the model. Therefore, we sought to assess how this oxysterol would affect lung inflammatory responses. In a model of lipopolysaccharide (LPS)-induced acute lung inflammation, 25-OHC levels were increased, and most of the hallmarks of the model (eg, leukocyte recruitment, mRNA expression, and secretion of inflammatory cytokines) were decreased following its intratracheal administration. We also found that, when administered in the lung, 25-OHC is metabolized locally into 25-hydroxycholesterol-3-sulfate and 7α,25-dihydroxycholesterol. Their administration in the lungs did not recapitulate all the effects of 25-OHC. Conversely, in a model of allergic asthma induced by intranasal administration of house dust mites (HDM), 25-OHC levels were decreased, and when intranasally administered, this oxysterol worsened the hallmarks of the model (eg, leukocyte recruitment, tissue remodeling [epithelium thickening and peribranchial fibrosis], and cytokine expression) and induced changes in leukotriene levels. Ex vivo, we found that 25-OHC decreases LPS-induced primary alveolar macrophage activation while having no effect on neutrophil activation. Its sulfated metabolite, 25-hydroxycholesterol-3-sulfate, decreased neutrophil, but not macrophage activation. Taken together, our data support a differential role of 25-OHC in ALI and allergic inflammation models.

5'AMP-activated protein kinase: an emerging target of phytochemicals to treat chronic inflammatory diseases.

Inflammation is a defensive response of the organism to traumatic, infectious, toxic, ischemic, and autoimmune injury. Inflammatory mediators are released to effectively eliminate the inflammatory trigger and restore homeostasis. However, failure of these processes can lead to chronic inflammatory conditions and diseases such as inflammatory bowel diseases, rheumatoid arthritis, inflammatory lung diseases, atherosclerosis, and neurodegenerative diseases. The cure of chronic inflammatory diseases remains challenging as current therapies have various limitations, such as pronounced side effects, progressive loss of efficacy, and high cost especially for biologics. In this context, phytochemicals (such as alkaloids, flavonoids, lignans, phenolic acids, saponins, terpenoids, and other classes) are considered as an interesting alternative approach. Among the numerous targets of phytochemicals, AMP-activated protein kinase (AMPK) can be considered as an interesting target in the context of inflammation. AMPK regulates inflammatory response by inhibiting inflammatory pathways (NF-κB, JAK/STAT, and MAPK) and regulating several other processes of the inflammatory response (oxidative stress, autophagy, and apoptosis). In this review, we summarize and discuss the studies focusing on phytochemicals that showed beneficial effects by blocking different inflammatory pathways implicating AMPK activation in chronic inflammatory disease models. We also highlight elements to consider when investigating AMPK in the context of phytochemicals.

Dereplication and Quantification of Major Compounds of Convolvulus arvensis L. Extracts and Assessment of Their Effect on LPS-Activated J774 Macrophages.

Convolvulus arvensis is used in Pakistani traditional medicine to treat inflammation-related disorders. Its anti-inflammatory potential was evaluated on hexane, dichloromethane, ethyl acetate, methanol, and aqueous extracts of whole plant on pro-inflammatory mediators in LPS-activated murine macrophage J774 cells at the non-cytotoxic concentration of 50 µg/mL. Ethyl acetate (ARE) and methanol (ARM) extracts significantly decreased mRNA levels of IL-6, TNF-α, MCP-1, COX-2, and iNOS. Furthermore, both extracts dose dependently decreased IL-6, TNF-α, and MCP-1 secretion. Forty-five compounds were putatively identified in ARE and ARM by dereplication (using HPLC-UV-HRMSn analysis and molecular networking), most of them are reported for the first time in C. arvensis, as for example, nineteen phenolic derivatives. Rutin, kaempferol-3-O-rutinoside, chlorogenic acid, 3,5-di-O-caffeoylquinic acid, N-trans-p-coumaroyl-tyramine, and N-trans-feruloyl-tyramine were main constituents identified and quantified by HPLC-PDA in ARE and ARM. Furthermore, chlorogenic acid, tyramine derivatives, and the mixture of the six identified major compounds significantly decreased IL-6 secretion by LPS-activated J774 cells. The activity of N-trans-p-coumaroyl-tyramine is shown here for the first time. Our results indicate that ARE, ARM and major constituents significantly inhibited the expression of pro-inflammatory mediators, which supports the use of this plant to treat inflammatory diseases.

Identification of new enterosynes using prebiotics: roles of bioactive lipids and mu-opioid receptor signalling in humans and mice.

OBJECTIVE: The enteric nervous system (ENS) plays a key role in controlling the gut-brain axis under normal and pathological conditions, such as type 2 diabetes. The discovery of intestinal actors, such as enterosynes, able to modulate the ENS-induced duodenal contraction is considered an innovative approach. Among all the intestinal factors, the understanding of the role of gut microbes in controlling glycaemia is still developed. We studied whether the modulation of gut microbiota by prebiotics could permit the identification of novel enterosynes. DESIGN: We measured the effects of prebiotics on the production of bioactive lipids in the intestine and tested the identified lipid on ENS-induced contraction and glucose metabolism. Then, we studied the signalling pathways involved and compared the results obtained in mice to human. RESULTS: We found that modulating the gut microbiota with prebiotics modifies the actions of enteric neurons, thereby controlling duodenal contraction and subsequently attenuating hyperglycaemia in diabetic mice. We discovered that the signalling pathway involved in these effects depends on the synthesis of a bioactive lipid 12-hydroxyeicosatetraenoic acid (12-HETE) and the presence of mu-opioid receptors (MOR) on enteric neurons. Using pharmacological approaches, we demonstrated the key role of the MOR receptors and proliferator-activated receptor γ for the effects of 12-HETE. These findings are supported by human data showing a decreased expression of the proenkephalin and MOR messanger RNAs in the duodenum of patients with diabetic. CONCLUSIONS: Using a prebiotic approach, we identified enkephalin and 12-HETE as new enterosynes with potential real beneficial and safety impact in diabetic human.

Glycerophosphodiesterase 3 (GDE3) is a lysophosphatidylinositol-specific ectophospholipase C acting as an endocannabinoid signaling switch.

Endocannabinoid signaling plays a regulatory role in various (neuro)biological functions. 2-arachidonoylglycerol (2-AG) is the most abundant endocannabinoid, and although its canonical biosynthetic pathway involving phosphoinositide-specific phospholipase C and diacylglycerol lipase α is known, alternative pathways remain unsettled. Here, we characterize a noncanonical pathway implicating glycerophosphodiesterase 3 (GDE3, from GDPD2 gene). Human GDE3 expressed in HEK293T cell membranes catalyzed the conversion of lysophosphatidylinositol (LPI) into monoacylglycerol and inositol-1-phosphate. The enzyme was equally active against 1-acyl and 2-acyl LPI. When using 2-acyl LPI, where arachidonic acid is the predominant fatty acid, LC-MS analysis identified 2-AG as the main product of LPI hydrolysis by GDE3. Furthermore, inositol-1-phosphate release into the medium occurred upon addition of LPI to intact cells, suggesting that GDE3 is actually an ecto-lysophospholipase C. In cells expressing G-protein-coupled receptor GPR55, GDE3 abolished 1-acyl LPI-induced signaling. In contrast, upon simultaneous ex-pression of GDE3 and cannabinoid receptor CB2, 2-acyl LPI evoked the same signal as that induced by 2-AG. These data strongly suggest that, in addition to degrading the GPR55 LPI ligand, GDE3 can act as a switch between GPR55 and CB2 signaling. Coincident with a major expression of both GDE3 and CB2 in the spleen, spleens from transgenic mice lacking GDE3 displayed doubling of LPI content compared with WT mice. Decreased production of 2-AG in whole spleen was also observed, supporting the in vivo relevance of our findings. These data thus open a new research avenue in the field of endocannabinoid generation and reinforce the view of GPR55 and LPI being genuine actors of the endocannabinoid system.

Prebiotic dietary fibre intervention improves fecal markers related to inflammation in obese patients: results from the Food4Gut randomized placebo-controlled trial.

PURPOSE: Inulin-type fructans (ITF) are prebiotic dietary fibre (DF) that may confer beneficial health effects, by interacting with the gut microbiota. We have tested the hypothesis that a dietary intervention promoting inulin intake versus placebo influences fecal microbial-derived metabolites and markers related to gut integrity and inflammation in obese patients. METHODS: Microbiota (16S rRNA sequencing), long- and short-chain fatty acids (LCFA, SCFA), bile acids, zonulin, and calprotectin were analyzed in fecal samples obtained from obese patients included in a randomized, placebo-controlled trial. Participants received either 16 g/d native inulin (prebiotic n = 12) versus maltodextrin (placebo n = 12), coupled to dietary advice to consume inulin-rich versus inulin-poor vegetables for 3 months, in addition to dietary caloric restriction. RESULTS: Both placebo and prebiotic interventions lowered energy and protein intake. A substantial increase in Bifidobacterium was detected after ITF treatment (q = 0.049) supporting our recent data obtained in a larger cohort. Interestingly, fecal calprotectin, a marker of gut inflammation, was reduced upon ITF treatment. Both prebiotic and placebo interventions increased the ratio of tauro-conjugated/free bile acids in feces. Prebiotic treatment did not significantly modify fecal SCFA content but it increased fecal rumenic acid, a conjugated linoleic acid (cis-9, trans-11 CLA) with immunomodulatory properties, that correlated notably to the expansion of Bifidobacterium (p = 0.031; r = 0.052). CONCLUSIONS: Our study demonstrates that ITF-prebiotic intake during 3 months decreases a fecal marker of intestinal inflammation in obese patients. Our data point to a potential contribution of microbial lipid-derived metabolites in gastro-intestinal dysfunction related to obesity. CLINICALTRIALS. GOV IDENTIFIER: NCT03852069 (February 22, 2019 retrospectively, registered).

Diesel exhaust particles alter the profile and function of the gut microbiota upon subchronic oral administration in mice.

BACKGROUND: Ambient air pollution by particulate matters, including diesel exhaust particles (DEP), is a major cause of cardiovascular and metabolic mortality worldwide. The mechanisms by which DEP cause these adverse outcomes are not completely understood. Because the gut microbiota controls cardiovascular and metabolic health, we hypothesized that the fraction of inhaled DEP which reach the gut after mucociliary clearance and swallowing might induce gut dysbiosis and, in turn, contribute to aggravate or induce cardiovascular and metabolic diseases. RESULTS: Female ApoE-/- mice fed a Western diet, and wild-type (C57Bl/6) mice fed standard diet were gavaged with DEP (SRM2975) doses corresponding to mucociliary clearance from inhalation exposure (200 or 1000 ng/day, 3 times a week for 3 months; and 40, 200 or 1000 ng/day, 3 times a week for 6 months, respectively). No mortality, overt systemic or digestive toxicity was observed. A dose-dependent alteration of the gut microbiota was recorded in both strains. In ApoE-/-, ß-diversity was modified by DEP, but no significant modification of the relative abundance of the phyla, families or genera was identified. In C57BL/6 mice, DEP reduced α-diversity (Shannon and Simpson indices), and modified ß-diversity, including a reduction of the Proteobacteria and Patescibacteria phyla, and an increase of the Campylobacterota phylum. In both mouse models, perturbation of the gut microbiota composition was associated with a dose-dependent reduction of bacterial short chain fatty acids (butyrate and propionate) in cecal content. However, DEP ingestion did not aggravate (ApoE-/-), or induce (C57BL/6 mice) atherosclerotic plaques, and no metabolic alteration (glucose tolerance, resistance to insulin, or lipidemia) was recorded. CONCLUSIONS: We show here that oral exposure to DEP, at doses relevant for human health, changes the composition and function of the gut microbiota. These modifications were, however, not translated into ultimate atherosclerotic or metabolic outcomes.

Systemic effects and impact on the gut microbiota upon subacute oral exposure to silver acetate in rats.

CONTEXT: The addition of silver (Ag) to food items, and its migration from food packaging and appliances results in a dietary exposure in humans, estimated to 70-90 µg Ag/day. In view of the well-known bactericidal activity of Ag ions, concerns arise about a possible impact of dietary Ag on the gut microbiota (GM), which is a master determinant of human health and diseases. Repeated oral administration of Ag acetate (AgAc) can also cause systemic toxicity in rats with reported NOAELs of 4 mg AgAc/b.w./d for impaired fertility and 0.4 mg AgAc/b.w./d for developmental toxicity. OBJECTIVE: The objective of this study was to investigate whether oral exposure to AgAc can induce GM alterations at doses causing reproductive toxicity in rats. METHODS: Male and female Wistar rats were exposed during 10 weeks to AgAc incorporated into food (0, 0.4, 4 or 40 mg/kg b.w./d), and we analyzed the composition of the GM (α- and ß-diversity). We documented bacterial function by measuring short-chain fatty acid (SCFA) production in cecal content. Ferroxidase activity, a biomarker of systemic Ag toxicity, was measured in serum. RESULTS AND CONCLUSIONS: From 4 mg/kg b.w./d onwards, we recorded systemic toxicity, as indicated by the reduction of serum ferroxidase activity, as well as serum Cu and Se concentrations. This systemic toxic response to AgAc might contribute to explain reprotoxic manifestations. We observed a dose-dependent modification of the GM composition in male rats exposed to AgAc. No impact of AgAc exposure on the production of bacterial SCFA was recorded. The limited GM changes recorded in this study do not appear related to a reprotoxicity outcome.

Germ-free mice exhibit profound gut microbiota-dependent alterations of intestinal endocannabinoidome signaling.

The gut microbiota is a unique ecosystem of microorganisms interacting with the host through several biochemical mechanisms. The endocannabinoidome (eCBome), a complex signaling system including the endocannabinoid system, approximately 50 receptors and metabolic enzymes, and more than 20 lipid mediators with important physiopathologic functions, modulates gastrointestinal tract function and may mediate host cell-microbe communications there. Germ-free (GF) mice, which lack an intestinal microbiome and so differ drastically from conventionally raised (CR) mice, offer a unique opportunity to explore the eCBome in a microbe-free model and in the presence of a reintroduced functional gut microbiome through fecal microbiota transplant (FMT). We aimed to gain direct evidence for a link between the microbiome and eCBome systems by investigating eCBome alterations in the gut in GF mice before and after FMT. Basal eCBome gene expression and lipid profiles were measured in various segments of the intestine of GF and CR mice at juvenile and adult ages using targeted quantitative PCR transcriptomics and LC-MS/MS lipidomics. GF mice exhibited age-dependent modifications in intestinal eCBome gene expression and lipid mediator levels. FMT from CR donor mice to age-matched GF male mice reversed several of these alterations, particularly in the ileum and jejunum, after only 1 week, demonstrating that the gut microbiome directly impacts the host eCBome and providing a cause-effect relationship between the presence or absence of intestinal microbes and eCBome signaling. These results open the way to new studies investigating the mechanisms through which intestinal microorganisms exploit eCBome signaling to exert some of their physiopathologic functions.

Acetate: Friend or foe against breast tumour growth in the context of obesity?

Acetate is reported as a regulator of fat mass but also as lipogenic source for cancer cells. Breast cancer is surrounded by adipose tissue and has been associated with obesity. However, whether acetate contributes to cancer cell metabolism as lipogenic substrate and/or by changing fat storage and eventually obesity-induced breast cancer progression remains unknown. Therefore, we studied the contribution of acetate to breast cancer metabolism and progression. In vitro, we found that acetate is not a bioenergetic substrate under normoxia and did not result in a significant change of growth. However, by using lipidomic approaches, we discovered that acetate changes the lipid profiles of the cells under hypoxia. Moreover, while mice fed a high-fat diet (HFD) developed bigger tumours than their lean counterparts, exogenous acetate supplementation leads to a complete abolishment of fat mass gain without reverting the HFD-induced obesity-driven tumour progression. In conclusion, although acetate protects against diet-induced obesity, our data suggest that it is not affecting HFD-driven tumour progression.