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

BACKGROUND: The gut microbiota contributes to metabolic disease, and diet shapes the gut microbiota, emphasizing the need to better understand how diet impacts metabolic disease via gut microbiota alterations. Fiber intake is linked with improvements in metabolic homeostasis in rodents and humans, which is associated with changes in the gut microbiota. However, dietary fiber is extremely heterogenous, and it is imperative to comprehensively analyze the impact of various plant-based fibers on metabolic homeostasis in an identical setting and compare the impact of alterations in the gut microbiota and bacterially derived metabolites from different fiber sources. OBJECTIVE: The objective of this study is to analyze the impact of different plant-based fibers (pectin, beta-glucan, wheat dextrin, resistant starch, and cellulose as a control) on metabolic homeostasis through alterations in the gut microbiota and its metabolites in high-fat diet (HFD)-fed mice. METHODS: HFD-fed mice were supplemented with 5 different fiber types (pectin, beta-glucan, wheat dextrin, resistant starch, or cellulose as a control) at 10% (w/w) for 18 weeks (n=12/group), measuring body weight, adiposity, indirect calorimetry, glucose tolerance, and the gut microbiota and metabolites. RESULTS: Only beta-glucan supplementation during HFD-feeding decreased adiposity and body weight gain and improved glucose tolerance compared to HFD-cellulose, while all other fibers had no effect. This was associated with increased energy expenditure and locomotor activity in mice compared to HFD-cellulose. All fibers supplemented into a HFD uniquely shifted the intestinal microbiota and cecal short-chain fatty acids, however only beta-glucan supplementation increased cecal butyrate levels. Lastly, all fibers altered the small intestinal microbiota and portal bile acid composition. CONCLUSIONS: These findings demonstrate that beta-glucan consumption is a promising dietary strategy for metabolic disease, possibly via increased energy expenditure through alterations in the gut microbiota and bacterial metabolites in mice.

Single cell transcriptomics unveiled that early life BDE-99 exposure reprogrammed the gut-liver axis to promote a pro-inflammatory metabolic signature in male mice at late adulthood.

Polybrominated diphenyl ethers (PBDEs) are legacy flame retardants that bioaccumulate in the environment. The gut microbiome is an important regulator of liver functions including xenobiotic biotransformation and immune regulation. We recently showed that neonatal exposure to polybrominated diphenyl ether-99 (BDE-99), a human breast milk-enriched PBDE congener, up-regulated pro-inflammation- and down-regulated drug metabolism-related genes predominantly in males in young adulthood. However, the persistence of dysregulation into late adulthood, differential impact of hepatic cell types, and the involvement of the gut microbiome from neonatal BDE-99 exposure remains unknown. To address these knowledge gaps, male C57BL/6 mouse pups were orally exposed to corn oil (10 ml/kg) or BDE-99 (57 mg/kg) once daily from postnatal days 2-4. At 15 months of age, neonatal BDE-99 exposure down-regulated xenobiotic and lipid metabolizing enzymes and up-regulated genes involved in microbial influx in hepatocytes. Neonatal BDE-99 exposure also increased the hepatic proportion of neutrophils and led to a predicted increase of macrophage migration inhibitory factor signaling. This was associated with decreased intestinal tight junction protein (Tjp) transcripts, altered gut environment, and dysregulation of inflammation-related metabolites. ScRNA-seq using germ-free (GF) mice demonstrated the necessity of a normal gut microbiome in maintaining hepatic immune tolerance. Microbiota transplant to GF mice using large intestinal microbiome from adults neonatally exposed to BDE-99 down-regulated Tjp transcripts and up-regulated several cytokines in the large intestine. In conclusion, neonatal BDE-99 exposure reprogrammed cell type-specific gene expression and communication in liver towards pro-inflammation, and BDE-99-mediated pro-inflammatory signatures may be partly due to the dysregulated gut environment.

In Vivo Tissue Distribution of Polystyrene or Mixed Polymer Microspheres and Metabolomic Analysis after Oral Exposure in Mice.

BACKGROUND: Global plastic use has consistently increased over the past century with several different types of plastics now being produced. Much of these plastics end up in oceans or landfills leading to a substantial accumulation of plastics in the environment. Plastic debris slowly degrades into microplastics (MPs) that can ultimately be inhaled or ingested by both animals and humans. A growing body of evidence indicates that MPs can cross the gut barrier and enter into the lymphatic and systemic circulation leading to accumulation in tissues such as the lungs, liver, kidney, and brain. The impacts of mixed MPs exposure on tissue function through metabolism remains largely unexplored. OBJECTIVES: This study aims to investigate the impacts of polymer microspheres on tissue metabolism in mice by assessing the microspheres ability to translocate across the gut barrier and enter into systemic circulation. Specifically, we wanted to examine microsphere accumulation in different organ systems, identify concentration-dependent metabolic changes, and evaluate the effects of mixed microsphere exposures on health outcomes. METHODS: To investigate the impact of ingested microspheres on target metabolic pathways, mice were exposed to either polystyrene (5µm) microspheres or a mixture of polymer microspheres consisting of polystyrene (5µm), polyethylene (1-4µm), and the biodegradability and biocompatible plastic, poly-(lactic-co-glycolic acid) (5µm). Exposures were performed twice a week for 4 weeks at a concentration of either 0, 2, or 4mg/week via oral gastric gavage. Tissues were collected to examine microsphere ingress and changes in metabolites. RESULTS: In mice that ingested microspheres, we detected polystyrene microspheres in distant tissues including the brain, liver, and kidney. Additionally, we report on the metabolic differences that occurred in the colon, liver, and brain, which showed differential responses that were dependent on concentration and type of microsphere exposure. DISCUSSION: This study uses a mouse model to provide critical insight into the potential health implications of the pervasive issue of plastic pollution. These findings demonstrate that orally consumed polystyrene or mixed polymer microspheres can accumulate in tissues such as the brain, liver, and kidney. Furthermore, this study highlights concentration-dependent and polymer type-specific metabolic changes in the colon, liver, and brain after plastic microsphere exposure. These results underline the mobility within and between biological tissues of MPs after exposure and emphasize the importance of understanding their metabolic impact. https://doi.org/10.1289/EHP13435.

Baseline gut microbiome and metabolites are correlated with alcohol consumption in a zonisamide clinical trial of heavy drinking alcoholic civilians.

Development and severity of alcohol use disorder (AUD) has been linked to variations in gut microbiota and their associated metabolites in both animal and human studies. However, the involvement of the gut microbiome in alcohol consumption of individuals with AUD undergoing treatment remains unclear. To address this, stool samples (n=48) were collected at screening (baseline) and trial completion from a single site of a multi-site double-blind, placebo-controlled trial of Zonisamide in individuals with AUD. Alcohol consumption, gamma-glutamyl transferase (GGT), and phosphatidylethanol (PEth)levels were measured both at baseline and endpoint of 16-week trial period. Fecal microbiome was analyzed via 16S rRNA sequencing and metabolome via untargeted LC-MS. Both sex (p = 0.003) and psychotropic medication usage (p = 0.025) are associated with baseline microbiome composition. The relative abundance of 12 genera at baseline was correlated with percent drinking reduction, baseline and endpoint alcohol consumption, and changes in GGT and PeTH over the course of treatment (p.adj < 0.05). Overall microbiome community structure at baseline differed between high and low responders (67-100% and 0-33% drinking reduction, respectively; p = 0.03). A positive relationship between baseline fecal GABA levels and percent drinking reduction (R=0.43, p < 0.05) was identified by microbiome function prediction and confirmed by ELISA and metabolomics. Predicted microbiome function and metabolomics analysis have found that tryptophan metabolic pathways are over-represented in low responders. These findings highlight importance of baseline microbiome and metabolites in alcohol consumption in AUD patients undergoing zonisamide treatment.

Inverse-Vaccines for Rheumatoid Arthritis Re-establish Metabolic and Immunological Homeostasis in Joint Tissues.

Rheumatoid arthritis (RA) causes immunological and metabolic imbalances in tissue, exacerbating inflammation in affected joints. Changes in immunological and metabolic tissue homeostasis at different stages of RA are not well understood. Herein, the changes in the immunological and metabolic profiles in different stages in collagen induced arthritis (CIA), namely, early, intermediate, and late stage is examined. Moreover, the efficacy of the inverse-vaccine, paKG(PFK15+bc2) microparticle, to restore tissue homeostasis at different stages is also investigated. Immunological analyses of inverse-vaccine-treated group revealed a significant decrease in the activation of pro-inflammatory immune cells and remarkable increase in regulatory T-cell populations in the intermediate and late stages compared to no treatment. Also, glycolysis in the spleen is normalized in the late stages of CIA in inverse-vaccine-treated mice, which is similar to no-disease tissues. Metabolomics analyses revealed that metabolites UDP-glucuronic acid and L-Glutathione oxidized are significantly altered between treatment groups, and thus might provide new druggable targets for RA treatment. Flux metabolic modeling identified amino acid and carnitine pathways as the central pathways affected in arthritic tissue with CIA progression. Overall, this study shows that the inverse-vaccines initiate early re-establishment of homeostasis, which persists through the disease span.

Single-cell and Spatial Transcriptomics Identified Fatty Acid-binding Proteins Controlling Endothelial Glycolytic and Arterial Programming in Pulmonary Hypertension.

Pulmonary arterial hypertension (PAH) is a devastating disease characterized by obliterative vascular remodeling and persistent increase of vascular resistance, leading to right heart failure and premature death. Understanding the cellular and molecular mechanisms will help develop novel therapeutic approaches for PAH patients. Single-cell RNA sequencing (scRNAseq) analysis found that both FABP4 and FABP5 were highly induced in endothelial cells (ECs) of Egln1Tie2Cre (CKO) mice, which was also observed in pulmonary arterial ECs (PAECs) from idiopathic PAH (IPAH) patients, and in whole lungs of pulmonary hypertension (PH) rats. Plasma levels of FABP4/5 were upregulated in IPAH patients and directly correlated with severity of hemodynamics and biochemical parameters using plasma proteome analysis. Genetic deletion of both Fabp4 and 5 in CKO mice (Egln1Tie2Cre/Fabp4-5-/- ,TKO) caused a reduction of right ventricular systolic pressure (RVSP) and RV hypertrophy, attenuated pulmonary vascular remodeling and prevented the right heart failure assessed by echocardiography, hemodynamic and histological analysis. Employing bulk RNA-seq and scRNA-seq, and spatial transcriptomic analysis, we showed that Fabp4/5 deletion also inhibited EC glycolysis and distal arterial programming, reduced ROS and HIF-2α expression in PH lungs. Thus, PH causes aberrant expression of FABP4/5 in pulmonary ECs which leads to enhanced ECs glycolysis and distal arterial programming, contributing to the accumulation of arterial ECs and vascular remodeling and exacerbating the disease.

Mitochondrial hyperfusion induces metabolic remodeling in lung endothelial cells by modifying the activities of electron transport chain complexes I and III.

OBJECTIVE: Pulmonary hypertension (PH) is a progressive disease with vascular remodeling as a critical structural alteration. We have previously shown that metabolic reprogramming is an early initiating mechanism in animal models of PH. This metabolic dysregulation has been linked to remodeling the mitochondrial network to favor fission. However, whether the mitochondrial fission/fusion balance underlies the metabolic reprogramming found early in PH development is unknown. METHODS: Utilizing a rat early model of PH, in conjunction with cultured pulmonary endothelial cells (PECs), we utilized metabolic flux assays, Seahorse Bioassays, measurements of electron transport chain (ETC) complex activity, fluorescent microscopy, and molecular approaches to investigate the link between the disruption of mitochondrial dynamics and the early metabolic changes that occur in PH. RESULTS: We observed increased fusion mediators, including Mfn1, Mfn2, and Opa1, and unchanged fission mediators, including Drp1 and Fis1, in a two-week monocrotaline-induced PH animal model (early-stage PH). We were able to establish a connection between increases in fusion mediator Mfn1 and metabolic reprogramming. Using an adenoviral expression system to enhance Mfn1 levels in pulmonary endothelial cells and utilizing 13C-glucose labeled substrate, we found increased production of 13C lactate and decreased TCA cycle metabolites, revealing a Warburg phenotype. The use of a 13C5-glutamine substrate showed evidence that hyperfusion also induces oxidative carboxylation. The increase in glycolysis was linked to increased hypoxia-inducible factor 1α (HIF-1α) protein levels secondary to the disruption of cellular bioenergetics and higher levels of mitochondrial reactive oxygen species (mt-ROS). The elevation in mt-ROS correlated with attenuated ETC complexes I and III activities. Utilizing a mitochondrial-targeted antioxidant to suppress mt-ROS, limited HIF-1α protein levels, which reduced cellular glycolysis and reestablished mitochondrial membrane potential. CONCLUSIONS: Our data connects mitochondrial fusion-mediated mt-ROS to the Warburg phenotype in early-stage PH development.

Novel Relationship between Mitofusin 2-Mediated Mitochondrial Hyperfusion, Metabolic Remodeling, and Glycolysis in Pulmonary Arterial Endothelial Cells.

The disruption of mitochondrial dynamics has been identified in cardiovascular diseases, including pulmonary hypertension (PH), ischemia-reperfusion injury, heart failure, and cardiomyopathy. Mitofusin 2 (Mfn2) is abundantly expressed in heart and pulmonary vasculature cells at the outer mitochondrial membrane to modulate fusion. Previously, we have reported reduced levels of Mfn2 and fragmented mitochondria in pulmonary arterial endothelial cells (PAECs) isolated from a sheep model of PH induced by pulmonary over-circulation and restoring Mfn2 normalized mitochondrial function. In this study, we assessed the effect of increased expression of Mfn2 on mitochondrial metabolism, bioenergetics, reactive oxygen species production, and mitochondrial membrane potential in control PAECs. Using an adenoviral expression system to overexpress Mfn2 in PAECs and utilizing 13C labeled substrates, we assessed the levels of TCA cycle metabolites. We identified increased pyruvate and lactate production in cells, revealing a glycolytic phenotype (Warburg phenotype). Mfn2 overexpression decreased the mitochondrial ATP production rate, increased the rate of glycolytic ATP production, and disrupted mitochondrial bioenergetics. The increase in glycolysis was linked to increased hypoxia-inducible factor 1α (HIF-1α) protein levels, elevated mitochondrial reactive oxygen species (mt-ROS), and decreased mitochondrial membrane potential. Our data suggest that disrupting the mitochondrial fusion/fission balance to favor hyperfusion leads to a metabolic shift that promotes aerobic glycolysis. Thus, therapies designed to increase mitochondrial fusion should be approached with caution.

NEUROMETABOLOMIC IMPACTS OF MODELED WILDFIRE SMOKE AND PROTECTIVE BENEFITS OF ANTI-AGING THERAPEUTICS IN AGED FEMALE C57BL/6J MICE.

Wildland fires have become progressively more extensive over the past 30 years in the US, and now routinely generate smoke that deteriorates air quality for most of the country. We explored the neurometabolomic impact that smoke derived from biomass has on older (18 months) female C57BL/6J mice, both acutely and after 10 weeks of recovery from exposures. Mice (N=6/group) were exposed to wood smoke (WS) 4 hours/day, every other day, for 2 weeks (7 exposures total) to an average concentration of 0.448mg/m 3 per exposure. One group was euthanized 24 hours after the last exposure. Other groups were then placed on 1 of 4 treatment regimens for 10 weeks after wood smoke exposures: vehicle; resveratrol in chow plus nicotinamide mononucleotide in water (RNMN); senolytics via gavage (dasatanib+quercetin; DQ); or both RNMN with DQ (RNDQ). Among the findings, the aging from 18 months to 21 months was associated with the greatest metabolic shift, including changes in nicotinamide metabolism, with WS exposure effects that were relatively modest. WS caused a reduction in NAD+ within the prefrontal cortex immediately after exposure and a long-term reduction in serotonin that persisted for 10 weeks. The serotonin reductions were corroborated by forced swim tests, which revealed an increased immobility (reduction in motivation) immediately post-exposure and persisted for 10 weeks. RNMN had the most beneficial effects after WS exposure, while RNDQ caused markers of brain aging to be upregulated within WS-exposed mice. Findings highlight the persistent neurometabolomic and behavioral effects of woodsmoke exposure in an aged mouse model. Significance Statement: Neurological impacts of wildfire smoke are largely underexplored but include neuroinflammation and metabolic changes. The present study highlights modulation of major metabolites in the prefrontal cortex and behavioral consequences in aged (18 month) female mice that persists 10 weeks after wood smoke exposure ended. Supplements derived from the anti-aging field were able to mitigate much of the woodsmoke effect, especially a combination of resveratrol and nicotinamide mononucleotide.

Identifying biodegradation pathways of cetrimonium bromide (CTAB) using metagenome, metatranscriptome, and metabolome tri-omics integration.

Traditional research on biodegradation of emerging organic pollutants involves slow and labor-intensive experimentation. Currently, fast-developing metagenome, metatranscriptome, and metabolome technologies promise to expedite mechanistic research on biodegradation of emerging organic pollutants. Integrating the metagenome, metatranscriptome, and metabolome (i.e., tri-omics) makes it possible to link gene abundance and expression with the biotransformation of the contaminant and the formation of metabolites from this biotransformation. In this study, we used this tri-omics approach to study the biotransformation pathways for cetyltrimethylammonium bromide (CTAB) under aerobic conditions. The tri-omics analysis showed that CTAB undergoes three parallel first-step mono-/di-oxygenations (to the α, ß, and ω-carbons); intermediate metabolites and expressed enzymes were identified for all three pathways, and the ß-carbon mono-/di-oxygenation is a novel pathway; and the genes related to CTAB biodegradation were associated with Pseudomonas spp. Four metabolites - palmitic acid, trimethylamine N-oxide (TMAO), myristic acid, and betaine - were the key identified biodegradation intermediates of CTAB, and they were associated with first-step mono-/di-oxygenations at the α/ß-C. This tri-omics approach with CTAB demonstrates its power for identifying promising paths for future research on the biodegradation of complex organics by microbial communities.

Higher Levels of Stress and Neuropsychological Symptoms Are Associated With a High Nausea Profile in Patients With Cancer Receiving Chemotherapy.

OBJECTIVES: To evaluate differences in the severity of global, cancer-specific, and cumulative life stress, resilience, and common neuropsychological symptoms among four subgroups of patients with distinct chemotherapy-induced nausea (CIN) profiles. SAMPLE & SETTING: Adult patients with cancer (N = 1,343) receiving chemotherapy. METHODS & VARIABLES: Patients completed stress, resilience, and neuropsychological symptom severity measures. The Memorial Symptom Assessment Scale was used to assess CIN occurrence six times over two cycles of chemotherapy. Parametric and nonparametric statistics were used to evaluate differences among subgroups of patients with distinct CIN profiles. RESULTS: The high class had significantly higher levels of global, cancer-specific, and cumulative life stress; significantly higher levels of depression, anxiety, sleep disturbance, morning and evening fatigue, and pain; and lower levels of morning and evening energy and cognitive dysfunction. IMPLICATIONS FOR NURSING: Clinicians need to evaluate CIN occurrence across each cycle of chemotherapy and assess patients for various types of stress and common neuropsychological symptoms.

Effects of Increased Standing and Light-Intensity Physical Activity to Improve Postprandial Glucose in Sedentary Office Workers: Protocol for a Randomized Crossover Trial.

BACKGROUND: Prolonged bouts of sedentary time, independent from the time spent in engaging in physical activity, significantly increases cardiometabolic risk. Nonetheless, the modern workforce spends large, uninterrupted portions of the day seated at a desk. Previous research suggests-via improved cardiometabolic biomarkers-that this risk might be attenuated by simply disrupting sedentary time with brief breaks of standing or moving. However, this evidence is derived from acute, highly controlled laboratory experiments and thus has low external validity. OBJECTIVE: This study aims to investigate if similar or prolonged cardiometabolic changes are observed after a prolonged (2-week) practice of increased brief standing and moving behaviors in real-world office settings. METHODS: This randomized crossover trial, called the WorkWell Study, will compare the efficacy of two 2-week pilot intervention conditions designed to interrupt sitting time in sedentary office workers (N=15) to a control condition. The intervention conditions use a novel smartphone app to deliver real-time prompts to increase standing (STAND) or moving (MOVE) by an additional 6 minutes each hour during work. Our primary aim is to assess intervention-associated improvements to daily postprandial glucose using continuous glucose monitors. Our secondary aim is to determine whether the interventions successfully evoke substantive positional changes and light-intensity physical activity (LPA). Other outcomes include the feasibility and acceptability of the intervention conditions, fasting blood glucose concentration, femoral artery flow-mediated dilation (f-FMD), and systolic and diastolic blood pressure. RESULTS: The trial is ongoing at the time of submission. CONCLUSIONS: This study is a novel, randomized crossover trial designed to extend a laboratory-based controlled study design into the free-living environment. By using digital health technologies to monitor and prompt participants in real time, we will be able to rigorously test the effects of breaking up sedentary behavior over a longer period of time than is seen in traditional laboratory-based studies. Our innovative approach will leverage the strengths of highly controlled laboratory and free-living experiments to achieve maximal internal and external validity. The research team's multidisciplinary expertise allows for a broad range of biological measures to be sampled, providing robust results that will extend knowledge of both the acute and chronic real-life effects of increased standing and LPA in sedentary office workers. The WorkWell Study uses a rigorous transdisciplinary protocol that will contribute to a more comprehensive picture of the beneficial effects of breaking up sitting behavior. TRIAL REGISTRATION: ClinicalTrials.gov NCT04269070; https://clinicaltrials.gov/study/NCT04269070. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/45133.

Increased cardiac PFK-2 protects against high-fat diet-induced cardiomyopathy and mediates beneficial systemic metabolic effects.

A healthy heart adapts to changes in nutrient availability and energy demands. In metabolic diseases like type 2 diabetes (T2D), increased reliance on fatty acids for energy production contributes to mitochondrial dysfunction and cardiomyopathy. A principal regulator of cardiac metabolism is 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2), which is a central driver of glycolysis. We hypothesized that increasing PFK-2 activity could mitigate cardiac dysfunction induced by high-fat diet (HFD). Wild type (WT) and cardiac-specific transgenic mice expressing PFK-2 (GlycoHi) were fed a low fat or HFD for 16 weeks to induce metabolic dysfunction. Metabolic phenotypes were determined by measuring mitochondrial bioenergetics and performing targeted quantitative proteomic and metabolomic analysis. Increasing cardiac PFK-2 had beneficial effects on cardiac and mitochondrial function. Unexpectedly, GlycoHi mice also exhibited sex-dependent systemic protection from HFD, including increased glucose homeostasis. These findings support improving glycolysis via PFK-2 activity can mitigate mitochondrial and functional changes that occur with metabolic syndrome.

Biomass smoke inhalation promotes neuroinflammatory and metabolomic temporal changes in the hippocampus of female mice.

Smoke from wildland fires has been shown to produce neuroinflammation in preclinical models, characterized by neural infiltrations of neutrophils and monocytes, as well as altered neurovascular endothelial phenotypes. To address the longevity of such outcomes, the present study examined the temporal dynamics of neuroinflammation and metabolomics after inhalation exposures from biomass-derived smoke. 2-month-old female C57BL/6 J mice were exposed to wood smoke every other day for 2 weeks at an average exposure concentration of 0.5 mg/m3. Subsequent serial euthanasia occurred at 1-, 3-, 7-, 14-, and 28-day post-exposure. Flow cytometry of right hemispheres revealed two endothelial populations of CD31Hi and CD31Med expressors, with wood smoke inhalation causing an increased proportion of CD31Hi. These populations of CD31Hi and CD31Med were associated with an anti-inflammatory and pro-inflammatory response, respectively, and their inflammatory profiles were largely resolved by the 28-day mark. However, activated microglial populations (CD11b+/CD45low) remained higher in wood smoke-exposed mice than controls at day 28. Infiltrating neutrophil populations decreased to levels below controls by day 28. However, the MHC-II expression of the peripheral immune infiltrate remained high, and the population of neutrophils retained an increased expression of CD45, Ly6C, and MHC-II. Utilizing an unbiased approach examining the metabolomic alterations, we observed notable hippocampal perturbations in neurotransmitter and signaling molecules, such as glutamate, quinolinic acid, and 5-α-dihydroprogesterone. Utilizing a targeted panel designed to explore the aging-associated NAD+ metabolic pathway, wood smoke exposure drove fluctuations and compensations across the 28-day time course, ending with decreased hippocampal NAD+ abundance on day 28. Summarily, these results indicate a highly dynamic neuroinflammatory environment, with potential resolution extending past 28 days, the implications of which may include long-term behavioral changes, systemic and neurological sequalae directly associated with wildfire smoke exposure.

In Vivo Tissue Distribution of Microplastics and Systemic Metabolomic Alterations After Gastrointestinal Exposure.

Global plastic use has consistently increased over the past century with several different types of plastics now being produced. Much of these plastics end up in oceans or landfills leading to a substantial accumulation of plastics in the environment. Plastic debris slowly degrades into microplastics (MPs) that can ultimately be inhaled or ingested by both animals and humans. A growing body of evidence indicates that MPs can cross the gut barrier and enter into the lymphatic and systemic circulation leading to accumulation in tissues such as the lungs, liver, kidney, and brain. The impacts of mixed MPs exposure on tissue function through metabolism remains largely unexplored. To investigate the impact of ingested MPs on target metabolomic pathways, mice were subjected to either polystyrene microspheres or a mixed plastics (5 µm) exposure consisting of polystyrene, polyethylene and the biodegradability and biocompatible plastic, poly-(lactic-co-glycolic acid). Exposures were performed twice a week for four weeks at a dose of either 0, 2, or 4 mg/week via oral gastric gavage. Our findings demonstrate that, in mice, ingested MPs can pass through the gut barrier, be translocated through the systemic circulation, and accumulate in distant tissues including the brain, liver, and kidney. Additionally, we report on the metabolomic changes that occur in the colon, liver and brain which show differential responses that are dependent on dose and type of MPs exposure. Lastly, our study provides proof of concept for identifying metabolomic alterations associated with MPs exposure and adds insight into the potential health risks that mixed MPs contamination may pose to humans.

Recent Review on Selected Xenobiotics and Their Impacts on Gut Microbiome and Metabolome.

As it is well known, the gut is one of the primary sites in any host for xenobiotics, and the many microbial metabolites responsible for the interactions between the gut microbiome and the host. However, there is a growing concern about the negative impacts on human health induced by toxic xenobiotics. Metabolomics, broadly including lipidomics, is an emerging approach to studying thousands of metabolites in parallel. In this review, we summarized recent advancements in mass spectrometry (MS) technologies in metabolomics. In addition, we reviewed recent applications of MS-based metabolomics for the investigation of toxic effects of xenobiotics on microbial and host metabolism. It was demonstrated that metabolomics, gut microbiome profiling, and their combination have a high potential to identify metabolic and microbial markers of xenobiotic exposure and determine its mechanism. Further, there is increasing evidence supporting that reprogramming the gut microbiome could be a promising approach to the intervention of xenobiotic toxicity.

Acute inhalation of tungsten particles results in early signs of cardiac injury.

Epidemiological studies have established that exposure to tungsten increases the risk of developing cardiovascular diseases. However, no studies have investigated how tungsten affects cardiac function or the development of cardiovascular disease. Inhalation of tungsten particulates is relevant in occupational settings, and inhalation of particulate matter has a known causative role in driving cardiovascular disease. This study examined if acute inhalation to tungsten particulates affects cardiac function and leads to heart tissue alterations. Female BALB/c mice were exposed to Filtered Air or 1.5 ± 0.23 mg/m3 tungsten particles, using a whole-body inhalation chamber, 4 times over the course of two weeks. Inhalation exposure resulted in mild pulmonary inflammation characterized by an increased percentage and number of macrophages and metabolomic changes in the lungs. Cardiac output was significantly decreased in the tungsten-exposed group. Additionally, A', an indicator of the amount of work required by the atria to fill the heart was elevated. Cardiac gene expression analysis revealed, tungsten exposure increased expression of pro-inflammatory cytokines, markers of remodeling and fibrosis, and oxidative stress genes. These data strongly suggest exposure to tungsten results in cardiac injury characterized by early signs of diastolic dysfunction. Functional findings are in parallel, demonstrating cardiac oxidative stress, inflammation, and early fibrotic changes. Tungsten accumulation data would suggest these cardiac changes are driven by systemic consequences of pulmonary damage.

Ceramide compensation by ceramide synthases preserves retinal function and structure in a retinal dystrophy mouse model.

Increasing evidence has supported the role of ceramide as a mediator of photoreceptor dysfunction or cell death in ceramide accumulation and deficiency contexts. TLCD3B, a non-canonical ceramide synthase, was previously identified in addition to the six canonical ceramide synthases (CerSs), and the Tlcd3b-/- mouse model exhibited both retinal dysfunction and degeneration. As previous canonical CerS-deficient mouse models failed to display retinal degeneration, the mechanisms of how TLCD3B interacts with CerSs have not been investigated. Additionally, as the ceramide profile of each CerS is distinct, it is unclear whether the overall level or the homeostasis of different ceramide species plays a critical role in photoreceptor degeneration. Interactions between TLCD3B with canonical CerSs expressed in the retina were examined by subretinally injecting recombinant adeno-associated virus 8 vectors containing the Cers2 (rAAV8-CerS2), Cers4 (rAAV8-CerS4) and Cers5 (rAAV8-CerS5) genes. Injection of all three rAAV8-CerS vectors restored retinal functions as indicated by improved electroretinogram responses, but only rAAV8-CerS5 successfully retained retinal morphology in Tlcd3b-/- mice. CerSs and TLCD3B played partially redundant roles. Additionally, rather than acting as an integral entity, different ceramide species had different impacts on retinal cells, suggesting that the maintenance of the overall ceramide profile is critical for retinal function.

Maternal PBDE exposure disrupts gut microbiome and promotes hepatic proinflammatory signaling in humanized PXR-transgenic mouse offspring over time.

Developmental exposure to the persistent environmental pollutant, polybrominated diphenyl ethers (PBDEs), is associated with increased diabetes prevalence. The microbial tryptophan metabolite, indole-3-propionic acid (IPA), is associated with reduced risk of type 2 diabetes and lower-grade inflammation and is a pregnane X receptor (PXR) activator. To explore the role of IPA in modifying the PBDE developmental toxicity, we orally exposed humanized PXR-transgenic (hPXR-TG) mouse dams to vehicle, 0.1 mg/kg/day DE-71 (an industrial PBDE mixture), DE-71+IPA (20 mg/kg/day), or IPA, from 4 weeks preconception to the end of lactation. Pups were weaned at 21 days of age and IPA supplementation continued in the corresponding treatment groups. Tissues were collected at various ages until 6 months of age (n = 5 per group). In general, the effect of maternal DE-71 exposure on the gut microbiome of pups was amplified over time. The regulation of hepatic cytokines and prototypical xenobiotic-sensing transcription factor target genes by DE-71 and IPA was age- and sex-dependent, where DE-71-mediated mRNA increased selected cytokines (Il10, Il12p40, Il1ß [both sexes], and [males]). The hepatic mRNA of the aryl hydrocarbon receptor (AhR) target gene Cyp1a2 was increased by maternal DE-71 and DE-71+IPA exposure at postnatal day 21 but intestinal Cyp1a1 was not altered by any of the exposures and ages. Maternal DE-71 exposure persistently increased serum indole, a known AhR ligand, in age- and sex-dependent manner. In conclusion, maternal DE-71 exposure produced a proinflammatory signature along the gut-liver axis, including gut dysbiosis, dysregulated tryptophan microbial metabolism, attenuated PXR signaling, and elevated AhR signaling in postweaned hPXR-TG pups over time, which was partially corrected by IPA supplementation.

Neuroinflammatory and Metabolomic Temporal Dynamics Following Wood Smoke Inhalation.

Smoke from wildland fires has been shown to produce neuroinflammation in preclinical models, characterized by neural infiltrations of neutrophils and monocytes, as well as altered neurovascular endothelial phenotypes. To address the longevity of such outcomes, the present study examined the neuroinflammatory and metabolomic temporal dynamics after inhalation exposures from biomass-derived smoke. 2-month-old female C57BL/6J mice were exposed to wood smoke every other day for two weeks at an average exposure concentration of 0.5mg/m 3 . Subsequent serial euthanasia occurred at 1-, 3-, 7-, 14-, and 28-days post-exposure. Flow cytometry of right hemispheres revealed two endothelial populations of PECAM (CD31), high and medium expressors, with wood smoke inhalation causing an increased proportion of PECAM Hi . These populations of PECAM Hi and PECAM Med were associated with an anti-inflammatory and pro-inflammatory response, respectively, and their inflammatory profiles were largely resolved by the 28-day mark. However, activated microglial populations (CD11b + /CD45 low ) remained higher in wood smoke-exposed mice than controls at day 28. Infiltrating neutrophil populations decreased to levels below controls by day 28. However, the MHC-II expression of the peripheral immune infiltrate remained high, and the population of neutrophils retained an increased expression of CD45, Ly6C, and MHC-II. Utilizing an unbiased approach examining the metabolomic alterations, we observed notable hippocampal perturbations in neurotransmitter and signaling molecules like glutamate, quinolinic acid, and 5-α-dihydroprogesterone. Utilizing a targeted panel designed to explore the aging-associated NAD + metabolic pathway, wood smoke exposure drove fluctuations and compensations across the 28-day time course, ending with decreased hippocampal NAD + abundance at day 28. Summarily, these results indicate a highly dynamic neuroinflammatory environment, with potential resolution extending past 28 days, the implications of which may include long-term behavioral changes, systemic and neurological sequalae directly associated wtith wildfire smoke exposure.