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Multiple sclerosis (MS) is a chronic inflammatory and degenerative disease of the central nervous system afflicting nearly three million individuals worldwide. Neuroimmune interactions between glial, neural, and immune cells play important roles in MS pathology and offer potential targets for therapeutic intervention. Here, we review underlying risk factors, mechanisms of MS pathogenesis, available disease modifying therapies, and examine the value of emerging technologies, which may address unmet clinical needs and identify novel therapeutic targets.

OBJECTIVE: This study aimed to assess the impact of time-restricted eating (TRE) on integrated skeletal muscle myofibrillar protein synthesis (MyoPS) rates in males with overweight/obesity.METHODS: A total of 18 healthy males (age 46 ± 5 years; BMI: 30 ± 2 kg/m2 ) completed this exploratory, parallel, randomized dietary intervention after a 3-day lead-in diet. Participants then consumed an isoenergetic diet (protein: ~1.0 g/kg body mass per day) following either TRE (10:00 a.m. to 6:00 p.m.) or an extended eating control (CON; 8:00 a.m. to 8:00 p.m.) protocol for 10 days. Integrated MyoPS rates were measured using deuterated water administration with repeated saliva, blood, and muscle sampling. Secondary measures included continuous glucose monitoring and body composition (dual-energy x-ray absorptiometry).RESULTS: There were no differences in daily integrated MyoPS rates (TRE: 1.28% ± 0.18% per day, CON: 1.26% ± 0.22% per day; p = 0.82) between groups. From continuous glucose monitoring, 24-hour total area under the curve was reduced following TRE (-578 ± 271 vs. CON: 12 ± 272 mmol/L × 24 hours; p = 0.001). Total body mass declined (TRE: -1.6 ± 0.9 and CON: -1.1 ± 0.7 kg; p CONCLUSION: Consuming food within an 8-hour time-restricted period does not lower daily MyoPS rates when compared with an isoenergetic diet consumed over 12 hours. Future research should investigate whether these results translate to free-living TRE.

Multiple sclerosis is a chronic inflammatory disease of the central nervous system1. Astrocytes are heterogeneous glial cells that are resident in the central nervous system and participate in the pathogenesis of multiple sclerosis and its model experimental autoimmune encephalomyelitis2,3. However, few unique surface markers are available for the isolation of astrocyte subsets, preventing their analysis and the identification of candidate therapeutic targets; these limitations are further amplified by the rarity of pathogenic astrocytes. Here, to address these challenges, we developed focused interrogation of cells by nucleic acid detection and sequencing (FIND-seq), a high-throughput microfluidic cytometry method that combines encapsulation of cells in droplets, PCR-based detection of target nucleic acids and droplet sorting to enable in-depth transcriptomic analyses of cells of interest at single-cell resolution. We applied FIND-seq to study the regulation of astrocytes characterized by the splicing-driven activation of the transcription factor XBP1, which promotes disease pathology in multiple sclerosis and experimental autoimmune encephalomyelitis4. Using FIND-seq in combination with conditional-knockout mice, in vivo CRISPR-Cas9-driven genetic perturbation studies and bulk and single-cell RNAsequencing analyses of samples frommouse experimental autoimmune encephalomyelitis and humans with multiple sclerosis, we identified a new role for the nuclear receptor NR3C2 and its corepressor NCOR2 in limiting XBP1-driven pathogenic astrocyte responses. In summary, we used FIND-seq to identify a therapeutically targetable mechanism that limits XBP1-driven pathogenic astrocyte responses. FIND-seq enables the investigation of previously inaccessible cells, including rare cell subsets defined by unique gene expression signatures or other nucleic acid markers.

Genome-wide association studies have identified risk loci linked to inflammatory bowel disease (IBD)(1)—a complex chronic inflammatory disorder of the gastrointestinal tract. The increasing prevalence of IBD in industrialized countries and the augmented disease risk observed in migrants who move into areas of higher disease prevalence suggest that environmental factors are also important determinants of IBD susceptibility and severity(2). However, the identification of environmental factors relevant to IBD and the mechanisms by which they influence disease has been hampered by the lack of platforms for their systematic investigation. Here we describe an integrated systems approach, combining publicly available databases, zebrafish chemical screens, machine learning and mouse preclinical models to identify environmental factors that control intestinal inflammation. This approach established that the herbicide propyzamide increases inflammation in the small and large intestine. Moreover, we show that an AHR–NF-κB–C/EBPβ signalling axis operates in T cells and dendritic cells to promote intestinal inflammation, and is targeted by propyzamide. In conclusion, we developed a pipeline for the identification of environmental factors and mechanisms of pathogenesis in IBD and, potentially, other inflammatory diseases.

Wildfire impacts on air quality and climate are expected to be exacerbated by climate change with the most pronounced impacts in the boreal biome. Despite the large geographic coverage, there is limited information on boreal forest wildfire emissions, particularly for organic compounds, which are critical inputs for air quality model predictions of downwind impacts. In this study, airborne measurements of 193 compounds from 15 instruments, including 173 non-methane organics compounds (NMOG), were used to provide the most detailed characterization, to date, of boreal forest wildfire emissions. Highly speciated measurements showed a large diversity of chemical classes highlighting the complexity of emissions. Using measurements of the total NMOG carbon (NMOGT), the ΣNMOG was found to be 50 % ± 3 % to 53 % ± 3 % of NMOGT, of which, the intermediate- and semi-volatile organic compounds (I/SVOCs) were estimated to account for 7 % to 10 %. These estimates of I/SVOC emission factors expand the volatility range of NMOG typically reported. Despite extensive speciation, a substantial portion of NMOGT remained unidentified (47 % ± 15 % to 50 % ± 15 %), with expected contributions from more highly-functionalized VOCs and I/SVOCs. The emission factors derived in this study improve wildfire chemical speciation profiles and are especially relevant for air quality modelling of boreal forest wildfires. These aircraft-derived emission estimates were further linked with those derived from satellite observations demonstrating their combined value in assessing variability in modelled emissions. These results contribute to the verification and improvement of models that are essential for reliable predictions of near-source and downwind pollution resulting from boreal forest wildfires.

Measurement-based estimates of greenhouse gas (GHG) emissions from complex industrial operations are challenging to obtain, but serve as an important, independent check on inventory-reported emissions. Such top–down estimates, while important for oil and gas (O&G) emissions globally, are particularly relevant for Canadian oil sands (OS) operations, which represent the largest O&G contributor to national GHG emissions. We present a multifaceted top–down approach for estimating CO2 emissions that combines aircraft-measured CO2/NOx emission ratios (ERs) with inventory and satellite-derived NOx emissions from Ozone Monitoring Instrument (OMI) and TROPOspheric Ozone Monitoring Instrument (TROPOMI) and apply it to the Athabasca Oil Sands Region (AOSR) in Alberta, Canada. Historical CO2 emissions were reconstructed for the surface mining region, and average top–down estimates were found to be >65% higher than facility-reported, bottom–up estimates from 2005 to 2020. Higher top–down vs. bottom–up emissions estimates were also consistently obtained for individual surface mining and in situ extraction facilities, which represent a growing category of energy-intensive OS operations. Although the magnitudes of the measured discrepancies vary between facilities, they combine such that the observed reporting gap for total AOSR emissions is ≥(31 ± 8) Mt for each of the last 3 years (2018–2020). This potential underestimation is large and broadly highlights the importance of continued review and refinement of bottom–up estimation methodologies and inventories. The ER method herein offers a powerful approach for upscaling measured facility-level or regional fossil fuel CO2 emissions by taking advantage of satellite remote sensing observations.

Cell–cell interactions in the central nervous system play important roles in neurologic diseases. However, little is known about the specific molecular pathways involved, and methods for their systematic identification are limited. Here, we developed a forward genetic screening platform that combines CRISPR-Cas9 perturbations, cell coculture in picoliter droplets, and microfluidic-based fluorescence-activated droplet sorting to identify mechanisms of cell–cell communication. We used SPEAC-seq (systematic perturbation of encapsulated associated cells followed by sequencing), in combination with in vivo genetic perturbations, to identify microglia-produced amphiregulin as a suppressor of disease-promoting astrocyte responses in multiple sclerosis preclinical models and clinical samples. Thus, SPEAC-seq enables the high-throughput systematic identification of cell–cell communication mechanisms.

Astrocytes are abundant glial cells in the central nervous system (CNS) that perform diverse functions in health and disease. Astrocyte dysfunction is found in numerous diseases, including multiple sclerosis, Alzheimer disease, Parkinson disease, Huntington disease and neuropsychiatric disorders. Astrocytes regulate glutamate and ion homeostasis, cholesterol and sphingolipid metabolism and respond to environmental factors, all of which have been implicated in neurological diseases. Astrocytes also exhibit significant heterogeneity, driven by developmental programmes and stimulus-specific cellular responses controlled by CNS location, cell-cell interactions and other mechanisms. In this Review, we highlight general mechanisms of astrocyte regulation and their potential as therapeutic targets, including drugs that alter astrocyte metabolism, and therapies that target transporters and receptors on astrocytes. Emerging ideas, such as engineered probiotics and glia-to-neuron conversion therapies, are also discussed. We further propose a concise nomenclature for astrocyte subsets that we use to highlight the roles of astrocytes and specific subsets in neurological diseases.

BackgroundWomen with a history of gestational diabetes mellitus (GDM) have a 7-fold higher risk of developing type 2 diabetes (T2D). It is estimated that 20-50% of women with GDM history will progress to T2D within 10 years after delivery. Intensive lactation could be negatively associated with this risk, but the mechanisms behind a protective effect remain unknown.MethodsIn this study, we utilized a prospective GDM cohort of 1010 women without T2D at 6-9 weeks postpartum (study baseline) and tested for T2D onset up to 8 years post-baseline (n=980). Targeted metabolic profiling was performed on fasting plasma samples collected at both baseline and follow-up (1-2 years post-baseline) during research exams in a subset of 350 women (216 intensive breastfeeding, IBF vs. 134 intensive formula feeding or mixed feeding, IFF/Mixed). The relationship between lactation intensity and circulating metabolites at both baseline and follow-up were evaluated to discover underlying metabolic responses of lactation and to explore the link between these metabolites and T2D risk.ResultsWe observed that lactation intensity was strongly associated with decreased glycerolipids (TAGs/DAGs) and increased phospholipids/sphingolipids at baseline. This lipid profile suggested decreased lipogenesis caused by a shift away from the glycerolipid metabolism pathway towards the phospholipid/sphingolipid metabolism pathway as a component of the mechanism underlying the benefits of lactation. Longitudinal analysis demonstrated that this favorable lipid profile was transient and diminished at 1-2 years postpartum, coinciding with the cessation of lactation. Importantly, when stratifying these 350 women by future T2D status during the follow-up (171 future T2D vs. 179 no T2D), we discovered that lactation induced robust lipid changes only in women who did not develop incident T2D. Subsequently, we identified a cluster of metabolites that strongly associated with future T2D risk from which we developed a predictive metabolic signature with a discriminating power (AUC) of 0.78, superior to common clinical variables (i.e., fasting glucose, AUC 0.56 or 2-h glucose, AUC 0.62).ConclusionsIn this study, we show that intensive lactation significantly alters the circulating lipid profile at early postpartum and that women who do not respond metabolically to lactation are more likely to develop T2D. We also discovered a 10-analyte metabolic signature capable of predicting future onset of T2D in IBF women. Our findings provide novel insight into how lactation affects maternal metabolism and its link to future diabetes onset.Trial registrationClinicalTrials.govNCT01967030.

Brain cancers carry bleak prognoses, with therapeutic advances helping only a minority of patients over the past decade. The brain tumour microenvironment (TME) is highly immunosuppressive and differs from that of other malignancies as a result of the glial, neural and immune cell populations that constitute it. Until recently, the study of the brain TME was limited by the lack of methods to de-convolute this complex system at the single-cell level. However, novel technical approaches have begun to reveal the immunosuppressive and tumour-promoting properties of distinct glial and myeloid cell populations in the TME, identifying new therapeutic opportunities. Here, we discuss the immune modulatory functions of microglia, monocyte-derived macrophages and astrocytes in brain metastases and glioma, highlighting their disease-associated heterogeneity and drawing from the insights gained by studying these malignancies and other neurological disorders. Lastly, we consider potential approaches for the therapeutic modulation of the brain TME.

The immune system of the central nervous system (CNS) consists primarily of innate immune cells. These are highly specialized macrophages found either in the parenchyma, called microglia, or at the CNS interfaces, such as leptomeningeal, perivascular, and choroid plexus macrophages. While they were primarily thought of as phagocytes, their function extends well beyond simple removal of cell debris during development and diseases. Brain-resident innate immune cells were found to be plastic, long-lived, and host to an outstanding number of risk genes for multiple pathologies. As a result, they are now considered the most suitable targets for modulating CNS diseases. Additionally, recent single-cell technologies enhanced our molecular understanding of their origins, fates, interactomes, and functional cell statesduring health and perturbation. Here, we review the current state of our understanding and challenges of the myeloid cell biology in the CNS and treatment options for related diseases.

BackgroundMany diseases may result from disrupted metabolic regulation. Metabolite-GWAS studies assess the association of polymorphic variants with metabolite levels in body fluids. While these studies are successful, they have a high cost and technical expertise burden due to combining the analytical biochemistry of metabolomics with the computational genetics of GWAS. Currently, there are 100s of standalone metabolomics and GWAS studies related to similar diseases or phenotypes. A method that could statically evaluate these independent studies to find novel metabolites-genes association is of high interest. Although such an analysis is limited to genes with known metabolite interactions due to the unpaired nature of the data sets, any discovered associations may represent biomarkers and druggable targets for treatment and prevention.MethodsWe developed a bioinformatics tool, metGWAS 1.0, that generates and statistically compares metabolic and genomic gene sets using a hypergeometric test. Metabolic gene sets are generated by mapping disease-associated metabolites to interacting proteins (genes) via online databases. Genomic gene sets are identified from a network representation of the GWAS Catalog comprising 100s of studies.ResultsThe metGWAS 1.0 tool was evaluated using standalone metabolomics datasets extracted from two metabolomics-GWAS case studies. In case-study 1, a cardiovascular disease association study, we identified nine genes (APOA5, PLA2G5, PLA2G2D, PLA2G2E, PLA2G2F, LRAT, PLA2G2A, PLB1, and PLA2G7) that interact with metabolites in the KEGG glycerophospholipid metabolism pathway and contain polymorphic variants associated with cardiovascular disease (P < 0.005). The gene APOA5 was matched from the original metabolomics-GWAS study. In case study 2, a urine metabolome study of kidney metabolism in healthy subjects, we found marginal significance (P = 0.10 and P = 0.13) for glycine, serine, and threonine metabolism and alanine, aspartate, and glutamate metabolism pathways to GWAS data relating to kidney disease.ConclusionThe metGWAS 1.0 platform provides insight into developing methods that bridge standalone metabolomics and disease and phenotype GWAS data. We show the potential to reproduce findings of paired metabolomics-GWAS data and provide novel associations of gene variation and metabolite expression.

Context Prolactin is a multifaceted hormone known to regulate lactation. In women with gestational diabetes mellitus (GDM) history, intensive lactation has been associated with lower relative risk of future type 2 diabetes (T2D). However, the role of prolactin in T2D development and maternal metabolism in women with a recent GDM pregnancy has not been ascertained. Objective We examined the relationships among prolactin, future T2D risk, and key clinical and metabolic parameters. Methods We utilized a prospective GDM research cohort (the SWIFT study) and followed T2D onset by performing 2-hour 75-g research oral glucose tolerance test (OGTT) at study baseline (6-9 weeks postpartum) and again annually for 2 years, and also by retrieving clinical diagnoses of T2D from 2 years through 10 years of follow up from electronic medical records. Targeted metabolomics and lipidomics were applied on fasting plasma samples collected at study baseline from 2-hour 75-g research OGTTs in a nested case-control study (100 future incident T2D cases vs 100 no T2D controls). Results Decreasing prolactin quartiles were associated with increased future T2D risk (adjusted odds ratio 2.48; 95% CI, 0.81-7.58; P = 0.05). In women who maintained normoglycemia during the 10-year follow-up period, higher prolactin at baseline was associated with higher insulin sensitivity (P = 0.038) and HDL-cholesterol (P = 0.01), but lower BMI (P = 0.001) and leptin (P = 0.002). Remarkably, among women who developed future T2D, prolactin was not correlated with a favorable metabolic status (all P > 0.05). Metabolomics and lipidomics showed that lower circulating prolactin strongly correlated with a T2D–high risk lipid profile, with elevated circulating neutral lipids and lower concentrations of specific phospholipids/sphingolipids. Conclusion In women with recent GDM pregnancy, low circulating prolactin is associated with specific clinical and metabolic parameters and lipid metabolites linked to a high risk of developing T2D.

Astrocytes are glial cells that are abundant in the central nervous system (CNS) and that have important homeostatic and disease-promoting functions1. However, little is known about the homeostatic anti-inflammatory activities of astrocytes and their regulation. Here, using high-throughput flow cytometry screening, single-cell RNA sequencing and CRISPR-Cas9-based cell-specific in vivo genetic perturbations in mice, we identify a subset of astrocytes that expresses the lysosomal protein LAMP12 and the death receptor ligand TRAIL3. LAMP1+TRAIL+ astrocytes limit inflammation in the CNS by inducing T cell apoptosis through TRAIL-DR5 signalling. In homeostatic conditions, the expression of TRAIL in astrocytes is driven by interferon-γ (IFNγ) produced by meningeal natural killer (NK) cells, in which IFNγ expression is modulated by the gut microbiome. TRAIL expression in astrocytes is repressed by molecules produced by T cells and microglia in the context of inflammation. Altogether, we show that LAMP1+TRAIL+ astrocytes limit CNS inflammation by inducing T cell apoptosis, and that this astrocyte subset is maintained by meningeal IFNγ+ NK cells that are licensed by the microbiome.

Aim To examine the mechanism of action of γ-aminobutyric acid (GABA) on β-cell proliferation and investigate if co-treatment with Ly49, a novel GABA type A receptor positive allosteric modulator (GABAA -R PAM), amplifies this effect. Methods Human or mouse islets were co-treated for 4-5 days with GABA and selected receptor or cell signalling pathway modulators. Immunofluorescence was used to determine protein co-localization, cell number or proliferation, and islet size. Osmotic minipumps were surgically implanted in mice to assess Ly49 effects on pancreatic β-cells. Results Amplification of GABAA -R signalling enhanced GABA-stimulated β-cell proliferation in cultured mouse islets. Co-treatment of GABA with an inhibitor specific for PI3K, mTORC1/2, or p70S6K, abolished GABA-stimulated β-cell proliferation in mouse and human islets. Nuclear p-AktSer473 and p-p70S6KThr421/Ser424 expression in pancreatic β-cells was increased in GABA-treated mice compared with vehicle-treated mice, an effect augmented with GABA and Ly49 co-treatment. Mice co-treated with GABA and Ly49 exhibited enhanced β-cell area and proliferation compared with GABA-treated mice. Furthermore, S961 injection (an insulin receptor antagonist) resulted in enhanced plasma insulin in GABA and Ly49 co-treated mice compared with GABA-treated mice. Importantly, GABA co-treated with Ly49 increased β-cell proliferation in human islets providing a potential application for human subjects. Conclusions We show that GABA stimulates β-cell proliferation via the PI3K/mTORC1/p70S6K pathway in both mouse and human islets. Furthermore, we show that Ly49 enhances the β-cell regenerative effects of GABA, showing potential in the intervention of diabetes.

Zika virus (ZIKV) is a flavivirus linked to multiple birth defects including microcephaly, known as congenital ZIKV syndrome. The identification of host factors involved in ZIKV replication may guide efficacious therapeutic interventions. In genome-wide transcriptional studies, we found that ZIKV infection triggers aryl hydrocarbon receptor (AHR) activation. Specifically, ZIKV infection induces kynurenine (Kyn) production, which activates AHR, limiting the production of type I interferons (IFN-I) involved in antiviral immunity. Moreover, ZIKV-triggered AHR activation suppresses intrinsic immunity driven by the promyelocytic leukemia (PML) protein, which limits ZIKV replication. AHR inhibition suppressed the replication of multiple ZIKV strains in vitro and also suppressed replication of the related flavivirus dengue. Finally, AHR inhibition with a nanoparticle-delivered AHR antagonist or an inhibitor developed for human use limited ZIKV replication and ameliorated newborn microcephaly in a murine model. In summary, we identified AHR as a host factor for ZIKV replication and PML protein as a driver of anti-ZIKV intrinsic immunity. Giovannoni et al. report that the aryl hydrocarbon receptor (AHR) is a novel host factor exploited by Zika virus and dengue virus to evade the immune response. AHR is a candidate target for the treatment of Zika virus congenital syndrome and dengue fever.

Rare CD4 T cells that contain HIV under antiretroviral therapy represent an important barrier to HIV cure1–3, but the infeasibility of isolating and characterizing these cells in their natural state has led to uncertainty about whether they possess distinctive attributes that HIV cure-directed therapies might exploit. Here we address this challenge using a microfluidic technology that isolates the transcriptomes of HIV-infected cells based solely on the detection of HIV DNA. HIV-DNA+ memory CD4 T cells in the blood from people receiving antiretroviral therapy showed inhibition of six transcriptomic pathways, including death receptor signalling, necroptosis signalling and antiproliferative Gα12/13 signalling. Moreover, two groups of genes identified by network co-expression analysis were significantly associated with HIV-DNA+ cells. These genes (n = 145) accounted for just 0.81% of the measured transcriptome and included negative regulators of HIV transcription that were higher in HIV-DNA+ cells, positive regulators of HIV transcription that were lower in HIV-DNA+ cells, and other genes involved in RNA processing, negative regulation of mRNA translation, and regulation of cell state and fate. These findings reveal that HIV-infected memory CD4 T cells under antiretroviral therapy are a distinctive population with host gene expression patterns that favour HIV silencing, cell survival and cell proliferation, with important implications for the development of HIV cure strategies.

Pancreatic islets respond metabolically to glucose by closing KATPchannels resulting in Ca2+-influx and insulin secretion. Previous work has revealed the importance of glycolytic flux in triggering insulin secretion. However, it is unclear whether the triggered (‘first phase’) secretion is further amplified by Ca2+-stimulation of mitochondrial NADH production and/or oxidative phosphorylation (OxPhos). Although commercially available tools have been developed to explore islet metabolism, these methods often overlook islet variability and have poor spatiotemporal resolution. To tease apart first phase glucose-stimulated respiration, we designed an islet-on-a-chip microfluidic device to simultaneously measure O2-consumption rate (OCR) and Ca2+-activity of individual islets with high temporal resolution. We used finite element analysis to optimize placement of sensor in optically clear microwells on a thin glass coverslip. The microfluidic channels were subsequently fabricated using O2-impermeable plastic to limit outside-in diffusion and push islets against the microsensor. We validated our device using living mouse islets and well-established modulators of respiration. By inhibiting glycolysis and mitochondrial pyruvate transport, we show that islet OxPhos is limited by NADH-substrate rather than ADP in low and high glucose. We subsequently imaged glucose-stimulated OCR and Ca2+-influx simultaneously to reveal a biphasic respiratory response that is determined by glycolytic flux through pyruvate kinase (PKM2) and independent of Ca2+. These data demonstrate the unique utility of our modular and optically clear O2-sensor to simultaneously measure glucose-stimulated OCR and Ca2+activity of multiple individual islets.

Summary: Glucose tolerance test and glucose stimulated insulin secretion are important measures to determine glucose homeostasis and islet function and assess diabetes. Here, we provide a protocol where glucose tolerance test is used to study glucose homeostasis and insulin secretion in vivo, followed by islet isolation and glucose stimulated insulin secretion to determine islet function ex vivo. This protocol enables evaluation of glucose homeostasis and islets in mice which can also be applied to rat, beta cell lines and human studies.For complete details on the use and execution of this profile, please refer to Al Rijjal et al. (2021).

Little is known regarding the impact of diet on the breast milk microbiome. We hypothesized that vegan, vegetarian, and omnivore diets would impact the human milk microbiota. We also aimed to explore associations between human milk fatty acid concentrations and microbial composition. A cross-sectional microbiome diversity analysis of human milk samples (N = 72) was performed using 16S rRNA amplicon sequencing. Human milk microbial diversity was not associated with diet type. However, analysis of microbiome in relation to fatty acid profiles revealed significant differences in the overall composition of the human milk microbiota between high (> 0.7% of total fat) and low (< 0.7%) trans-fatty acid groups (TF) (p = 0.039, pairwise PERMANOVA p = 0.035), high (> 40%) versus low (< 40%) saturated fatty acids (UniFrac p = 0.083, PERMANOVA p = 0.094), and high (>60%) versus low (p = 0.094, PERMANOVA p = 0.093). 84% of samples from omnivore mothers were in the high TF group compared to only 12% of samples from vegans. Gut-associated species (Faecalibacterium, Blautia, Roseburia and Subdoligranulum) and Lactobacillus were characteristic of both high UF and TF groups, but not the low-fat groups. Functional analysis revealed 2,4-dichlorophenol 6-monooxygenase was differentially abundant in the high UF group. Although microbiome diversity did not differ by diet type, TF breast milk content differed by diet group, highlighting the relationship between maternal diet and the microbial profile of human milk.

MicroRNAs (miRNAs) expressed in the hypothalamus are capable of regulating energy balance and peripheral metabolism by inhibiting translation of target messenger RNAs (mRNAs). Hypothalamic insulin resistance is known to precede that in the periphery, thus a critical unanswered question is whether central insulin resistance creates a specific hypothalamic miRNA signature that can be identified and targeted. Here we show that miR-1983, a unique miRNA, is upregulated in vitro in 2 insulin-resistant immortalized hypothalamic neuronal neuropeptide Y-expressing models, and in vivo in hyperinsulinemic mice, with a concomitant decrease of insulin receptor β subunit protein, a target of miR-1983. Importantly, we demonstrate that miR-1983 is detectable in human blood serum and that its levels significantly correlate with blood insulin and the homeostatic model assessment of insulin resistance. Levels of miR-1983 are normalized with metformin exposure in mouse hypothalamic neuronal cell culture. Our findings provide evidence for miR-1983 as a unique biomarker of cellular insulin resistance, and a potential therapeutic target for prevention of human metabolic disease.

Reactive organic compounds play a central role in the formation of ozone and secondary organic aerosols. The ability to accurately predict their fate, in part, relies upon quantitative knowledge of the chemical and physical parameters associated with the total organic carbon (TOC), which includes both precursors and oxidation products that evolve in the atmosphere over short to long time scales. However, such knowledge, obtained via limited carbon closure experiments, has not been attained for complex anthropogenic emissions. Here we present the first comprehensive characterization of TOC in the atmospheric oxidation of organic vapors from light and heavy oil mixtures associated with oil sand operations. Despite the complexity of the investigated oil mixtures, we are able to achieve carbon closure (83-116%) within the uncertainties (±20%), with the degree of the closure being dependent upon the vapor composition and NOx levels. In contrast to biogenic precursors (e.g., α-pinene), the photochemical time scale required for a largely complete oxidation and evolution of chemical parameters is very long for the petrochemical vapors (i.e., ∼7-10 days vs ∼1 day), likely due to the lower initial precursor reactivity. This suggests that petrochemical emissions and their impacts are likely to extend further spatially than biogenic emissions, and retain more of their complex composition and reactivity for many days. The results of this work provide key parameters to regional models for further improving the representation of the chemical evolution of petrochemical emissions.

Multiple sclerosis is a chronic inflammatory disease of the CNS(1). Astrocytes contribute to the pathogenesis of multiple sclerosis(2), but little is known about the heterogeneity of astrocytes and its regulation. Here we report the analysis of astrocytes in multiple sclerosis and its preclinical model experimental autoimmune encephalomyelitis (EAE) by single-cell RNA sequencing in combination with cell-specific Ribotag RNA profiling, assay for transposase-accessible chromatin with sequencing (ATAC–seq), chromatin immunoprecipitation with sequencing (ChIP–seq), genome-wide analysis of DNA methylation and in vivo CRISPR–Cas9-based genetic perturbations. We identified astrocytes in EAE and multiple sclerosis that were characterized by decreased expression of NRF2 and increased expression of MAFG, which cooperates with MAT2α to promote DNA methylation and represses antioxidant and anti-inflammatory transcriptional programs. Granulocyte–macrophage colony-stimulating factor (GM-CSF) signalling in astrocytes drives the expression of MAFG and MAT2α and pro-inflammatory transcriptional modules, contributing to CNS pathology in EAE and, potentially, multiple sclerosis. Our results identify candidate therapeutic targets in multiple sclerosis.

Astrocytes are abundant glial cells in the central nervous system (CNS) that control multiple aspects of health and disease. Through their interactions with components of the blood–brain barrier (BBB), astrocytes not only regulate BBB function, they also sense molecules produced by peripheral immune cells, including cytokines. Here, we review the interactions between immune cells and astrocytes and their roles in health and neurological diseases, with a special focus on multiple sclerosis (MS). We highlight known pathways that participate in astrocyte crosstalk with microglia, NK cells, T cells, and other cell types; their contribution to the pathogenesis of neurological diseases; and their potential value as therapeutic targets.

Overconsumption of saturated fats promotes obesity and type 2 diabetes. Excess weight gain in early life may be particularly detrimental by promoting earlier diabetes onset and potentially by adversely affecting normal development. In the present study we investigated the effects of dietary fat composition on early overnutrition-induced body weight and glucose regulation in Swiss Webster mice, which show susceptibility to high-fat diet-induced diabetes. We compared glucose homeostasis between a high-fat lard-based (HFL) diet, high in saturated fats, and a high-fat olive oil/fish oil-based (HFO) diet, high in monounsaturated and omega-3 fats. We hypothesized that the healthier fat profile of the latter diet would improve early overnutrition-induced glucose dysregulation. However, early overnutrition HFO pups gained more weight and adiposity and had higher diabetes incidence compared to HFL. In contrast, control pups had less weight gain, adiposity, and lower diabetes incidence. Plasma metabolomics revealed reductions in various phosphatidylcholine species in early overnutrition HFO mice as well as with diabetes. These findings suggest that early overnutrition may negate any beneficial effects of a high-fat diet that favours monounsaturated and omega-3 fats over saturated fats. Thus, quantity, quality, and timing of fat intake throughout life should be considered with respect to metabolic health outcomes.

Summary Omega-3 fatty acid prescription drugs, Vascepa (≥96% eicosapentaenoic acid [EPA] ethyl ester) and Lovaza (46.5% EPA and 37.5% docosahexaenoic acid ethyl ester) are known therapeutic regimens to treat hypertriglyceridemia. However, their impact on glucose homeostasis, progression to type 2 diabetes, and pancreatic beta cell function are not well understood. In the present study, mice were treated with Vascepa or Lovaza for one week prior to six weeks of high-fat diet feeding. Vascepa but not Lovaza led to reduced insulin resistance, reduced fasting insulin and glucose, and improved glucose intolerance. Vascepa improved beta cell function, reduced liver triglycerides with enhanced expression of hepatic fatty acid oxidation genes, and altered microbiota composition. Vascepa has protective effects on diet-induced insulin resistance and glucose intolerance in mice., Graphical abstract, Highlights • Vascepa, an EPA ethyl ester prescription drug, protects from diet-induced weight gain • Acute exposure to Vascepa protects from glucose intolerance and beta cell dysfunction • Improved islet function is associated with improved insulin resistance • Vascepa upregulates hepatic fatty acid oxidation genes and alters gut microbiome, Dietary supplement; Human metabolism

GWAS have shown that the common R325W variant of SLC30A8 (ZnT8) increases the risk of type 2 diabetes (T2D). However, ZnT8 haploinsufficiency is protective against T2D in humans, counterintuitive to earlier work in humans and mouse models. Therefore, whether decreasing ZnT8 activity is beneficial or detrimental to β cell function, especially under conditions of metabolic stress, remains unknown. In order to examine whether the existence of human islet amyloid polypeptide (hIAPP), a coresident of the insulin granule, affects the role of ZnT8 in regulating β cell function, hIAPP-expressing transgenics were generated with reduced ZnT8 (ZnT8B+/- hIAPP) or null ZnT8 (ZnT8B-/- hIAPP) expression specifically in β cells. We showed that ZnT8B-/- hIAPP mice on a high-fat diet had intensified amyloid deposition and further impaired glucose tolerance and insulin secretion compared with control, ZnT8B-/-, and hIAPP mice. This can in part be attributed to impaired glucose sensing and islet cell synchronicity. Importantly, ZnT8B+/- hIAPP mice were also glucose intolerant and had reduced insulin secretion and increased amyloid aggregation compared with controls. These data suggest that loss of or reduced ZnT8 activity in β cells heightened the toxicity induced by hIAPP, leading to impaired β cell function and glucose homeostasis associated with metabolic stress.

Over the past decade or so, there has been significant progress towards elucidating the molecular events occurring during pollination in flowering plants. This process involves a series of complex cellular interactions that culminates in the fusion between male and female gametes. The process also regulates crucial events such as pollen adhesion, hydration, pollen tube growth and guidance to the ovules. Additionally, in many instances, incompatibility mechanisms that control the acceptance or rejection of pollen alighting on a recipient plant play a major role in the pollination process. In this article we aim to review our current understanding of the components that are implicated in enabling the pollen to deliver the male gametes to the ovary and the molecular mechanisms by which they are thought to act. Contents Summary 565 I. Introduction 565 II. Adhesion of pollen to the stigma 566 III. Pollen hydration 567 IV. Pollen germination and initial growth on the stigma surface 568 V. Pollen tube growth through the style and pollen tube guidance 569 VI. Control of pollen viability by incompatibility responses 572 1. Self incompatibility (SI) 573 Gametophytic SI 573 SI in the Solanaceae 573 SI in Papaver 575 Sporophytic SI 577 SI in Brassica 577 SI in Ipomoea 579 2. Interspecific incompatibility responses 579 VII. Conclusions and perspective 580 References 580.

The Athabasca Oil Sands Region (AOSR) in Alberta, Canada is one of the largest sources of extractable oil in the world. To better understand its impact, Environment and Climate Change Canada led two intensive measurement campaigns, in 2013 (August to September) and 2018 (April to July). Each included airborne measurements in which dozens of species were measured using a variety of in situ instruments. In this presentation, a method is described in which these aircraft measurements were examined to find species that were well correlated with NOx (the sum of NO and NO2) in order to derive their annual emissions. The species found to have a good correlation with NOx were black carbon, CO, HCN, HONO, CH4, and SO2. The annual emissions were found by applying individual species to NOx ratios to the satellite-derived NOx emissions from the TROPOspheric Monitoring Instrument (TROPOMI). The emissions derived in this way were compared with emissions reported to the National Pollutant Release Inventory (NPRI), as well as emissions derived from the aircraft measurements using the Top-down Emission Rate Retrieval Algorithm (TERRA). Additionally, Ozone Monitoring Instrument (OMI) NOx emissions were used to estimate historical changes in species emissions over time, between 2005 and 2020.