One-carbon metabolism and folate transporter genes: Do they factor prominently in the genetic etiology of neural tube defects?

The incorporation of MALDI mass spectrometry imaging in studies to identify markers of toxicity following in utero opioid exposures in mouse fetuses

Introduction

In 2015, the FDA released a Drug Safety Communication regarding a possible link between opioid exposure during early pregnancy and an increased risk of fetal neural tube defects (NTDs). At the time, the indications for opioid use during pregnancy were not changed due to incomplete maternal toxicity data and limitations in human and animal studies. To assess these knowledge gaps, largescale animal studies are ongoing; however, state-of-the-art technologies have emerged as promising tools to assess otherwise non-standard endpoints. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is a dynamic approach capable of generating 2D ion images to visualize the distribution of an analyte of interest across a tissue section.

Methods

Given the importance of lipid metabolism and neurotransmitters in the developing central nervous system, this study incorporates MALDI MSI to assess lipid distributions across mouse gestational day (GD) 18 fetuses, with and without observable NTDs following maternal exposure on GD 8 to morphine (400 mg/kg BW) or the NTD positive control valproic acid (VPA) (500 mg/kg BW).

Results

Analysis of whole-body mouse fetuses revealed differential lipid distributions localized mainly in the brain and spinal cord, which included several phosphatidylcholine (PC) species such as PCs 34:1, 34:0, and 36:2 localized to the cortex or hippocampus and lyso PC 16:0 across all brain regions. Overall, differential lipids increased in with maternal morphine and VPA exposure. Neurotransmitter distributions across the brain using FMP-10 derivatizing agent were also assessed, revealing morphine-specific changes.

Discussion

The observed differential glycerophospholipid distributions in relation to treatment and NTD development in mouse fetuses provide potential targets for further investigation of molecular mechanisms of opioid-related developmental effects. Overall, these findings support the feasibility of incorporating MALDI MSI to assess non-standard endpoints of opioid exposure during gestation.

Mitochondria in the Central Nervous System in Health and Disease: The Puzzle of the Therapeutic Potential of Mitochondrial Transplantation

Mitochondria, the energy suppliers of the cells, play a central role in a variety of cellular processes essential for survival or leading to cell death. Consequently, mitochondrial dysfunction is implicated in numerous general and CNS disorders. The clinical manifestations of mitochondrial dysfunction include metabolic disorders, dysfunction of the immune system, tumorigenesis, and neuronal and behavioral abnormalities. In this review, we focus on the mitochondrial role in the CNS, which has unique characteristics and is therefore highly dependent on the mitochondria. First, we review the role of mitochondria in neuronal development, synaptogenesis, plasticity, and behavior as well as their adaptation to the intricate connections between the different cell types in the brain. Then, we review the sparse knowledge of the mechanisms of exogenous mitochondrial uptake and describe attempts to determine their half-life and transplantation long-term effects on neuronal sprouting, cellular proteome, and behavior. We further discuss the potential of mitochondrial transplantation to serve as a tool to study the causal link between mitochondria and neuronal activity and behavior. Next, we describe mitochondrial transplantation's therapeutic potential in various CNS disorders. Finally, we discuss the basic and reverse-translation challenges of this approach that currently hinder the clinical use of mitochondrial transplantation.

Noncanonical function of folate through folate receptor 1 during neural tube formation

Folate supplementation reduces the occurrence of neural tube defects (NTDs), birth defects consisting in the failure of the neural tube to form and close. The mechanisms underlying NTDs and their prevention by folate remain unclear. Here we show that folate receptor 1 (FOLR1) is necessary for the formation of neural tube-like structures in human-cell derived neural organoids. FOLR1 knockdown in neural organoids and in Xenopus laevis embryos leads to NTDs that are rescued by pteroate, a folate precursor that is unable to participate in metabolism. We demonstrate that FOLR1 interacts with and opposes the function of CD2-associated protein, molecule essential for apical endocytosis and turnover of C-cadherin in neural plate cells. In addition, folates increase Ca2+ transient frequency, suggesting that folate and FOLR1 signal intracellularly to regulate neural plate folding. This study identifies a mechanism of action of folate distinct from its vitamin function during neural tube formation.

One carbon metabolism and its implication in health and immune functions

One carbon (1C) metabolism is critical for cellular viability and physiological homeostasis. Starting from its crucial involvement in purine biosynthesis to posttranslational modification of proteins, 1C metabolism contributes significantly to the development and cellular differentiation through methionine and folate cycles that are pivotal for cellular function. Genetic polymorphisms of several genes of these pathways are implicated in disease pathogenesis and drug metabolism. Metabolic products of 1C metabolism have significant roles in epigenetic modifications through DNA and histone protein methylation. Homocysteine is a product that has clinical significance in the diagnosis and prognosis of several critical illnesses, including chronic immune diseases and cancers. Regulation of the function and differentiation of immune cells, including T-cells, B-cells, macrophages, and so forth, are directly influenced by 1C metabolism and thus have direct implications in several immune disease biology. Recent research on therapeutic approaches is targeting nuclear, cytoplasmic, and mitochondrial 1C metabolism to manage and treat metabolic (i.e., type 2 diabetes), neurodegenerative (i.e., Alzheimer's disease), or immune (i.e., rheumatoid arthritis) diseases. 1C metabolism is being explored for therapeutic intervention as a common determinant for a spectrum of immune and metabolic diseases. Identifying the association or correlation between essential metabolic products of this pathway and disease onset or prognosis would further facilitate the clinical monitoring of diseases.

Proteome changes in autosomal recessive primary microcephaly

BACKGROUND/AIM

Autosomal recessive primary microcephaly (MCPH) is a rare and genetically heterogeneous group of disorders characterized by intellectual disability and microcephaly at birth, classically without further organ involvement. MCPH3 is caused by biallelic variants in the cyclin-dependent kinase 5 regulatory subunit-associated protein 2 gene CDK5RAP2. In the corresponding Cdk5rap2 mutant or Hertwig's anemia mouse model, congenital microcephaly as well as defects in the hematopoietic system, germ cells and eyes have been reported. The reduction in brain volume, particularly affecting gray matter, has been attributed mainly to disturbances in the proliferation and survival of early neuronal progenitors. In addition, defects in dendritic development and synaptogenesis exist that affect the excitation-inhibition balance. Here, we studied proteomic changes in cerebral cortices of Cdk5rap2 mutant mice.

MATERIAL AND METHODS

We used large-gel two-dimensional gel (2-DE) electrophoresis to separate cortical proteins. 2-DE gels were visualized by a trained observer on a light box. Spot changes were considered with respect to presence/absence, quantitative variation and altered mobility.

RESULT

We identified a reduction in more than 30 proteins that play a role in processes such as cell cytoskeleton dynamics, cell cycle progression, ciliary functions and apoptosis. These proteome changes in the MCPH3 model can be associated with various functional and morphological alterations of the developing brain.

CONCLUSION

Our results shed light on potential protein candidates for the disease-associated phenotype reported in MCPH3.

Doubly bi-allelic variants of MTHFR and MTHFD1 in a Chinese patient with hyperhomocysteinemia and failure of folic acid therapy

Background: Hyperhomocysteinemia (HHcy) is a risk factor for thromboembolic disease. Defects in one-carbon metabolism (1-CM)-related genes, such as methylenetetrahydrofolate reductase (MTHFR), methylenetetrahydrofolate dehydrogenase, cyclohydrolase, and formyltetrahydrofolate synthetase 1 (MTHFD1), can cause HHcy and may also affect the efficacy of folic acid therapy. The details of mechanisms are yet to be further investigated. Method: We described a Chinese family with hereditary HHcy. The proband suffered from severe thromboembolic disease and experienced failure of folic acid therapy. Two sons of the proband were also diagnosed with HHcy but were sensitive to folic acid therapy. Whole-exome sequencing (WES) was conducted to evaluate the genetic lesion of this family. Results: Compound heterozygous variants (a common polymorphism, p. A222V, and a novel variant, p. C631*fs*1) of the MTHFR gene and a homozygous missense variant (p. K134R) of the MTHFD1 gene were identified in the proband. The two sons, with successful intervention, only harbored the homozygous p. A222V variant of the MTHFR gene. Conclusion: The clinical manifestations and genetic research synergistically confirmed the diagnosis of HHcy and clarified the failure of folic acid therapy in the proband caused by doubly bi-allelic variants of the MTHFR and MTHFD1 genes. Our study increased our understanding of the molecular basis of 1-CM-related gene defects on folic acid therapy in HHcy.

HIV-1 Integrase Strand Transfer Inhibitors and Neurodevelopment

Children born to mothers, with or at risk, of human immunodeficiency virus type-1 (HIV-1) infection are on the rise due to affordable access of antiretroviral therapy (ART) to pregnant women or those of childbearing age. Each year, up to 1.3 million HIV-1-infected women on ART have given birth with recorded mother-to-child HIV-1 transmission rates of less than 1%. Despite this benefit, the outcomes of children exposed to antiretroviral drugs during pregnancy, especially pre- and post- natal neurodevelopment remain incompletely understood. This is due, in part, to the fact that pregnant women are underrepresented in clinical trials. This is underscored by any potential risks of neural tube defects (NTDs) linked, in measure, to periconceptional usage of dolutegravir (DTG). A potential association between DTG and NTDs was first described in Botswana in 2018. Incidence studies of neurodevelopmental outcomes associated with DTG, and other integrase strand transfer inhibitors (INSTIs) are limited as widespread use of INSTIs has begun only recently in pregnant women. Therefore, any associations between INSTI use during pregnancy, and neurodevelopmental abnormalities remain to be explored. Herein, United States Food and Drug Administration approved ARVs and their use during pregnancy are discussed. We provide updates on INSTI pharmacokinetics and adverse events during pregnancy together with underlying mechanisms which could affect fetal neurodevelopment. Overall, this review seeks to educate both clinical and basic scientists on potential consequences of INSTIs on fetal outcomes as a foundation for future scientific investigations.

Mitochondrial FAD shortage in SLC25A32 deficiency affects folate-mediated one-carbon metabolism

The SLC25A32 dysfunction is associated with neural tube defects (NTDs) and exercise intolerance, but very little is known about disease-specific mechanisms due to a paucity of animal models. Here, we generated homozygous (Slc25a32Y174C/Y174C and Slc25a32K235R/K235R) and compound heterozygous (Slc25a32Y174C/K235R) knock-in mice by mimicking the missense mutations identified from our patient. A homozygous knock-out (Slc25a32-/-) mouse was also generated. The Slc25a32K235R/K235R and Slc25a32Y174C/K235R mice presented with mild motor impairment and recapitulated the biochemical disturbances of the patient. While Slc25a32-/- mice die in utero with NTDs. None of the Slc25a32 mutations hindered the mitochondrial uptake of folate. Instead, the mitochondrial uptake of flavin adenine dinucleotide (FAD) was specifically blocked by Slc25a32Y174C/K235R, Slc25a32K235R/K235R, and Slc25a32-/- mutations. A positive correlation between SLC25A32 dysfunction and flavoenzyme deficiency was observed. Besides the flavoenzymes involved in fatty acid β-oxidation and amino acid metabolism being impaired, Slc25a32-/- embryos also had a subunit of glycine cleavage system-dihydrolipoamide dehydrogenase damaged, resulting in glycine accumulation and glycine derived-formate reduction, which further disturbed folate-mediated one-carbon metabolism, leading to 5-methyltetrahydrofolate shortage and other folate intermediates accumulation. Maternal formate supplementation increased the 5-methyltetrahydrofolate levels and ameliorated the NTDs in Slc25a32-/- embryos. The Slc25a32K235R/K235R and Slc25a32Y174C/K235R mice had no glycine accumulation, but had another formate donor-dimethylglycine accumulated and formate deficiency. Meanwhile, they suffered from the absence of all folate intermediates in mitochondria. Formate supplementation increased the folate amounts, but this effect was not restricted to the Slc25a32 mutant mice only. In summary, we established novel animal models, which enabled us to understand the function of SLC25A32 better and to elucidate the role of SLC25A32 dysfunction in human disease development and progression.

Hypermethylation of PI3K-AKT signalling pathway genes is associated with human neural tube defects

Neural tube defects (NTDs) are a group of common and severe congenital malformations. The PI3K-AKT signalling pathway plays a crucial role in the neural tube development. There is limited evidence concerning any possible association between aberrant methylation in PI3K-AKT signalling pathway genes and NTDs. Therefore, we aimed to investigate potential associations between aberrant methylation of PI3K-AKT pathway genes and NTDs. Methylation studies of PI3K-AKT pathway genes utilizing microarray genome-methylation data derived from neural tissues of ten NTD cases and eight non-malformed controls were performed. Targeted DNA methylation analysis was subsequently performed in an independent cohort of 73 NTD cases and 32 controls to validate the methylation levels of identified genes. siRNAs were used to pull-down the target genes in human embryonic stem cells (hESCs) to examine the effects of the aberrant expression of target genes on neural cells. As a result, 321 differentially hypermethylated CpG sites in the promoter regions of 30 PI3K-AKT pathway genes were identified in the microarray data. In target methylation analysis, CHRM1, FGF19, and ITGA7 were confirmed to be significantly hypermethylated in NTD cases and were associated with increased risk for NTDs. The down-regulation of FGF19, CHRM1, and ITGA7 impaired the formation of rosette-like cell aggregates. The down-regulation of those three genes affected the expression of PAX6, SOX2 and MAP2, implying their influence on the differentiation of neural cells. This study for the first time reported that hypermethylation of PI3K-AKT pathway genes such as CHRM1, FGF19, and ITGA7 is associated with human NTDs.

Interaction between dolutegravir and folate transporters and receptor in human and rodent placenta

Background

Due to the critical role of folates in neurodevelopment, it is important to understand potential interactions between anti-HIV drugs used during pregnancy, and folate delivery pathways in the placenta. This study investigates the effect of dolutegravir (DTG) exposure on the functional expression of the reduced folate carrier (RFC), proton-coupled folate transporter (PCFT), and folate receptor-α (FRα) in the placenta.

Methods

Human placental cell lines, human placental explants, and a pregnant mouse model treated with clinically relevant concentrations of DTG were used. Gene and protein expression were assessed by qPCR, immunoblot and immunohistochemical assays. Folate transport function was measured by applying radioisotope-based transport assays.

Findings

In placental cells, clinically relevant DTG exposure for 3h or 6h was associated with a modest but significant reduction in the expression of RFC and PCFT both at the mRNA and protein levels, as well as decreased uptake of RFC and PCFT substrates [³H]-methotrexate and [³H]-folic acid, respectively. In pregnant mice, DTG administration was associated with an increase in both placental RFC and PCFT mRNA expression, accompanied by a decrease in placental FRα mRNA under folate-deficient dietary conditions.

Interpretation

These findings demonstrate a potential interaction between DTG and folate transport pathways in the placenta, particularly in vivo, under folate deficient conditions, potentially impacting folate delivery to the foetus in the context of DTG-based ART during pregnancy.

Funding

Funded by Ontario HIV Treatment Network, grant #506657; and Eunice Kennedy Shriver National Institute of Child Health & Human Development of the National Institutes of Health, award #R01HD104553.

Mitochondria in Early Forebrain Development: From Neurulation to Mid-Corticogenesis

Function of the mature central nervous system (CNS) requires a substantial proportion of the body’s energy consumption. During development, the CNS anlage must maintain its structure and perform stage-specific functions as it proceeds through discrete developmental stages. While key extrinsic signals and internal transcriptional controls over these processes are well appreciated, metabolic and mitochondrial states are also critical to appropriate forebrain development. Specifically, metabolic state, mitochondrial function, and mitochondrial dynamics/localization play critical roles in neurulation and CNS progenitor specification, progenitor proliferation and survival, neurogenesis, neural migration, and neurite outgrowth and synaptogenesis. With the goal of integrating neurodevelopmental biologists and mitochondrial specialists, this review synthesizes data from disparate models and processes to compile and highlight key roles of mitochondria in the early development of the CNS with specific focus on forebrain development and corticogenesis.

Molecular Insight into the Effect of a Single-Nucleotide Polymorphic Variation on the Structure and Dynamics of Methionine Synthase Reductase and Its Association with Neural Tube Defects

Neural tube defects (NTDs) are among the common and severe congenital malformations in neonates. According to a WHO report, nearly three lakh babies are affected per year worldwide by NTDs. Most studies revealed that folate deficiency is the key element to promote NTD with other oligogenic and multifactorial elements. This folate is metabolized by the FOCM (folate one-carbon metabolism) pathway. The most important step in the FOCM pathway is the conversion of methionine to homocysteine, which is guided by the enzyme MTRR. Several single-nucleotide polymorphisms (SNPs) in the MTRR gene are strongly associated with the progression of NTD. A nonsynonymous allelic variant (rs1532268) of the protein leads to a missense mutation at the 202nd position from serine to leucine (S202L) and is associated with a higher disease prevalence in different populations. In our study, this SNP indicates a 2-fold increase in the risk of disease progression (p-value of 0.03; OR 2.76; 95% CI 1.08-7.11). Here, extensive molecular dynamics simulations and interaction network analysis reveal that the change of 202nd serine to leucine alters the structures of the FAD and NAD binding domains, which restricts the ligand binding. The S202L variation alters the functional dynamics that might impede the electron transport chain along the NADP(H)→ FAD→ FMN pathway and hamper phosphorylation by kinases like GSK-3 and CaM-II during the posttranscriptional modification of the protein. The present study provides functional insights into the effect of the genetic variations of the MTRR gene on the NTD disease pathogenesis.

Folic Acid-Coated Nanochitosan Ameliorated the Growth Performance, Hematological Parameters, Antioxidant Status, and Immune Responses of Rainbow Trout (Oncorhynchus mykiss)

In recent years, chitosan has gained considerable attention due to its favorable properties such as excellent biocompatibility and biodegradability for which it can be used as a health supplement for delivering bioactive compounds in the food industry and nutrition. In the present study, the effect of nanochitosans coated with folic acid (FA) was considered on the growth performance, hematological parameters, antioxidant status, and serum immune responses of rainbow trout (Oncorhynchus mykiss) fingerlings. Graded levels of FA-coated nanochitosan (0, 0.1, 0.25, 0.5, and 1 mg kg⁻¹ diet) were added to the basal diet, and each experimental diet was fed to three groups of fish with an approximate weight of 31 g for 8 weeks. The experimental study demonstrated that dietary FA-coated nanochitosan significantly (P < 0.05) improved the weight gain ration (WGR), specific growth rate (SGR), and feed conversion ratio (FCR) of fish at the end of the feeding trial. There were also linearly increasing trends in red blood cells (RBCs), white blood cells (WBCs), hemoglobin (Hb), and hematocrit (Hct) of fish fed with increasing dietary chitosan/FA levels, whereas no significant difference was recorded in differential leukocyte count of fish among the treatments. In case of antioxidant responses, fish fed diet supplemented with 0.50 mg kg⁻¹ FA-coated nanochitosan had the highest CAT and SOD activities, while the maximum activity of GPX was found in fish fed diet supplemented with 1.00 mg kg⁻¹ FA-coated nanochitosan. Malondialdehyde activity also reached the lowest value in fish fed with 1.00 mg kg⁻¹ FA-coated nanochitosan-supplemented diet (P < 0.05). Measured immune responses showed a linear augmentation in lysozyme activity (LA) with increasing dietary FA-coated nanochitosan, while linearly and quadratically increasing trends were recorded in immunoglobulin M (IgM) content as well as complement component C3 and C4 activities by increasing the supplementation of nanochitosan coated with FA (P < 0.05). Findings of the current study illustrated the positive effect of dietary FA-coated nanochitosan as a promising compound on improving the growth performance, feed utilization, antioxidant status, and immune responses of rainbow trout.

Nutritional Supplements for the Treatment of Neuropathic Pain

Neuropathic pain affects 7-10% of the population and is often ineffectively and incompletely treated. Although the gold standard for treatment of neuropathic pain includes tricyclic antidepressants (TCAs), serotonin-noradrenaline reuptake inhibitors, and anticonvulsants, patients suffering from neuropathic pain are increasingly turning to nonpharmacologic treatments, including nutritional supplements for analgesia. So-called "nutraceuticals" have garnered significant interest among patients seeking to self-treat their neuropathic pain with readily available supplements. The supplements most often used by patients include vitamins such as vitamin B and vitamin D, trace minerals zinc and magnesium, and herbal remedies such as curcumin and St. John's Wort. However, evidence surrounding the efficacy and mechanisms of these supplements in neuropathic pain is limited, and the scientific literature consists primarily of preclinical animal models, case studies, and small randomized controlled trials (RCTs). Further exploration into large randomized controlled trials is needed to fully inform patients and physicians on the utility of these supplements in neuropathic pain. In this review, we explore the basis behind using several nutritional supplements commonly used by patients with neuropathic pain seen in rheumatology clinics.

Associations of Plasma Folate and Vitamin B6 With Blood DNA Methylation Age: An Analysis of One-Carbon Metabolites in the VA Normative Aging Study

One-carbon metabolism is an important contributor to aging-related diseases; nevertheless, relationships of one-carbon metabolites with novel DNA methylation-based measures of biological aging remain poorly characterized. We examined relationships of one-carbon metabolites with 3 DNA methylation-based measures of biological aging: DNAmAge, GrimAge, and PhenoAge. We measured plasma levels of 4 common one-carbon metabolites (vitamin B6, vitamin B12, folate, and homocysteine) in 715 VA Normative Aging Study participants with at least 1 visit between 1999 and 2008 (observations = 1153). DNA methylation age metrics were calculated using the HumanMethylation450 BeadChip. We utilized Bayesian Kernel Machine Regression models adjusted for chronological age, lifestyle factors, age-related diseases, and study visits to determine metabolites important to the aging outcomes. Bayesian Kernel Machine Regression models allowed for the estimation of the relationships of single metabolites and the cumulative metabolite mixture with methylation age. Log vitamin B6 was selected as important to PhenoAge (β = -1.62 years, 95% CI: -2.28, -0.96). Log folate was selected as important to GrimAge (β = 0.75 years, 95% CI: 0.41, 1.09) and PhenoAge (β = 1.62 years, 95% CI: 0.95, 2.29). Compared to a model where each metabolite in the mixture is set to its 50th percentile, the log cumulative mixture with each metabolite at its 30th (β = -0.13 years, 95% CI: -0.26, -0.005) and 40th percentile (β = -0.06 years, 95% CI: -0.11, -0.005) was associated with decreased GrimAge. Our results provide novel characterizations of the relationships between one-carbon metabolites and DNA methylation age in a human population study. Further research is required to confirm these findings and establish their generalizability.

Proteomic analysis of body wall and coelomic fluid in Sipunculus nudus

In order to make clear the protein compositions of Sipunculus nudus and investigate its immune-related proteins, proteomic analysis was performed on body wall and coelomic fluid of Sipunculus nudus. A total of 1659 proteins were identified, and 539 proteins were differentially expressed in the coelomic fluid compared to those in the body wall, of which 415 proteins were up-regulated while 124 proteins were down-regulated. Gene Ontology (GO) analysis showed that the GO terms involved in the two parts of Sipunculus nudus were similar, with metabolic processes, catalytic activity and cell occupying the top categories of biological process, molecular function and cellular component, respectively. KEGG pathway analysis showed that 49 pathways in body wall and 48 in coelomic fluid were mapped respectively, and these pathways were mainly related to cellular processes, environmental information processing, genetic information processing and metabolism. The COG analysis showed that 757 proteins from body wall and 889 from coelomic fluid were classified into 26 COG categories, respectively. Pfam annotation revealed the mainly immune-related proteins contained in Sipunculus nudus, such as insulin-like growth factor binding protein, catalase, basement membrane proteoglycan, titin. Our research provides the first proteomic information of Sipunculus nudus, which contributes to the study of functional proteins in Sipunculus nudus and is of great significance for the application of Sipunculus nudus in functional foods and medicines.

Metabolic profiling reveals alterations in the erythrocyte response to fava bean ingestion in G6PD-deficient mice

BACKGROUND

Favism is an acute hemolytic syndrome caused by fava bean (FB) ingestion. The purpose of this study was to investigate the possible influences of FB on the metabonomic profile of erythrocytes in glucose-6-phosphate dehydrogenase (G6PD)-deficient (G6PDx) and wild-type (WT) mice.

RESULTS

Ninety-two metabolites were identified in the comparison of the G6PDx and WT groups. Eighty-seven metabolites were identified in the erythrocytes of WT and G6PDx mice after FB ingestion. Thirty-eight metabolites were identified in the comparison of the FB-treated G6PDx and the FB-treated WT mouse groups. Among them, the number of glycerophospholipids (GPLs) and polyunsaturated fatty acids (PUFAs) changed significantly, which suggests that GPLs and PUFAs may be responsible for FB stress.

CONCLUSION

This study demonstrates that G6PD deficiency might affect the metabonomic profile of erythrocytes in response to FB. © 2020 Society of Chemical Industry.

Maternal body condition influences neonatal calf whole-blood innate immune molecular responses to ex vivo lipopolysaccharide challenge

Managing body condition in dairy cows during the close-up period could alter the availability of nutrients to the fetus during the final growth stages in utero. We investigated how maternal body condition score (BCS) in late pregnancy affected calf whole-blood mRNA abundance and IL-1β concentrations after ex vivo lipopolysaccharide (LPS) challenge. Thirty-eight multiparous Holstein cows and their calves from a larger cohort were retrospectively grouped by prepartal BCS as normal BCS (≤3.25; n = 22; NormBCS) and high BCS (≥3.75; n = 16; HighBCS). Calf blood samples collected at birth (before receiving colostrum, d 0) and at ages 21 and 42 d (at weaning) were used for ex vivo whole-blood challenge with 3 µg/mL of LPS before mRNA isolation. Target genes evaluated by real-time quantitative PCR were associated with immune response, antioxidant function, and 1-carbon metabolism. Plasma IL-1β concentrations were also measured. Responses in plasma IL-1β and mRNA abundance were compared between LPS-challenged and nonchallenged samples. Statistical analyses were performed at all time points using a MIXED model in SAS 9.4. Neither birth body weight (NormBCS = 43.8 ± 1.01 kg; HighBCS = 43.9 ± 1.2 kg) nor colostrum IgG concentration (NormBCS = 70 ± 5.4 mg/mL; HighBCS = 62 ± 6.5 mg/mL) differed between groups. At birth, whole blood from calves born to HighBCS cows had greater mRNA abundance of IL1B, NFKB1, and GSR and lower GPX1 and CBS abundance after LPS challenge. The longitudinal analysis of d 0, 21, and 42 data revealed a BCS × age effect for SOD2 and NOS2 due to lower mRNA abundance at 42 d in the HighBCS calves. Regardless of maternal BCS, mRNA abundance decreased over time for genes encoding cytokines (IL1B, IL6, IL10, TNF), cytokine receptors (IRAK1, CXCR1), toll-like receptor pathway (TLR4, NFKB1), adhesion and migration (CADM1, ICAM1, ITGAM), and antimicrobial function (MPO). Concentration of IL-1β after LPS challenge was also markedly lower at 21 d regardless of maternal BCS. Overall, results suggested that maternal BCS in late prepartum influences the calf immune system response to an inflammation challenge after birth. Although few genes among those studied were altered due to maternal BCS, the fact that genes related to oxidative stress and 1-carbon metabolism responded to LPS challenge in HighBCS calves underscores the potential role of methyl donors (e.g., methionine, choline, and folic acid) in the early-life innate immune response.

B Vitamins and One-Carbon Metabolism: Implications in Human Health and Disease

Vitamins B9 (folate) and B12 are essential water-soluble vitamins that play a crucial role in the maintenance of one-carbon metabolism: a set of interconnected biochemical pathways driven by folate and methionine to generate methyl groups for use in DNA synthesis, amino acid homeostasis, antioxidant generation, and epigenetic regulation. Dietary deficiencies in B9 and B12, or genetic polymorphisms that influence the activity of enzymes involved in the folate or methionine cycles, are known to cause developmental defects, impair cognitive function, or block normal blood production. Nutritional deficiencies have historically been treated with dietary supplementation or high-dose parenteral administration that can reverse symptoms in the majority of cases. Elevated levels of these vitamins have more recently been shown to correlate with immune dysfunction, cancer, and increased mortality. Therapies that specifically target one-carbon metabolism are therefore currently being explored for the treatment of immune disorders and cancer. In this review, we will highlight recent studies aimed at elucidating the role of folate, B12, and methionine in one-carbon metabolism during normal cellular processes and in the context of disease progression.

Mouse models to study the pathophysiology of combined methylmalonic acidemia and homocystinuria, cblC type

Combined methylmalonic acidemia and homocystinuria, cblC type, is the most common inherited disorder of cobalamin metabolism and is characterized by severe fetal developmental defects primarily impacting the central nervous system, hematopoietic system, and heart. CblC was previously shown to be due to mutations in the MMACHC gene, which encodes a protein thought to function in intracellular cobalamin trafficking and biosynthesis of adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl). These coenzymes are required for the production of succinyl-CoA and methionine, respectively. However, it is currently unclear whether additional roles for MMACHC exist outside of cobalamin metabolism. Furthermore, due to a lack of sufficient animal models, the exact pathophysiology of cblC remains unknown. Here, we report the generation and characterization of two new mouse models to study the role of MMACHC in vivo. CRISPR/Cas9 genome editing was used to develop a Mmachc floxed allele (Mmachc^flox/flox), which we validated as a conditional null. For a gain-of-function approach, we generated a transgenic mouse line that over-expresses functional Mmachc (Mmachc-OE^+/tg) capable of rescuing Mmachc homozygous mutant lethality. Surprisingly, our data also suggest that these mice may exhibit a partially penetrant maternal-effect rescue, which might have implications for in utero therapeutic interventions to treat cblC. Both the Mmachc^flox/flox and Mmachc-OE^+/tg mouse models will be valuable resources for understanding the biological roles of MMACHC in a variety of tissue contexts and allow for deeper understanding of the pathophysiology of cblC.